Quantifying Dissolved Transition Metals in Battery Electrolyte
Solutions with NMR Paramagnetic Relaxation Enhancement
Jennifer P. Allen, Christopher A. O’Keefe, and Clare P. Grey*

Cite This: J. Phys. Chem. C 2023, 127, 9509−9521 Read Online

ACCESS Metrics & More Article Recommendations *sı Supporting Information

ABSTRACT: Transition metal dissolution is an important contributor to capacity
fade in lithium-ion cells. NMR relaxation rates are proportional to the
concentration of paramagnetic species, making them suitable to quantify dissolved
transition metals in battery electrolytes. In this work, 7Li, 31P, 19F, and 1H
longitudinal and transverse relaxation rates were measured to study LiPF6
electrolyte solutions containing Ni2+, Mn2+, Co2+, or Cu2+ salts and Mn dissolved
from LiMn2O4. Sensitivities were found to vary by nuclide and by transition metal.
19F (PF6−) and 1H (solvent) measurements were more sensitive than 7Li and 31P
measurements due to the higher likelihood that the observed species are in closer
proximity to the metal center. Mn2+ induced the greatest relaxation enhancement,
yielding a limit of detection of ∼0.005 mM for 19F and 1H measurements. Relaxometric analysis of a sample containing Mn dissolved
from LiMn2O4 at ∼20 °C showed good sensitivity and accuracy (suggesting dissolution of Mn2+), but analysis of a sample stored at
60 °C showed that the relaxometric quantification is less accurate for heat-degraded LiPF6 electrolytes. This is attributed to
degradation processes causing changes to the metal solvation shell (changing the fractions of PF6−, EC, and EMC coordinated to
Mn2+), such that calibration measurements performed with pristine electrolyte solutions are not applicable to degraded solutions�a
potential complication for efforts to quantify metal dissolution during operando NMR studies of batteries employing widely-used
LiPF6 electrolytes. Ex situ nondestructive quantification of transition metals in lithium-ion battery electrolytes is shown to be possible
by NMR relaxometry; further, the method’s sensitivity to the metal solvation shell also suggests potential use in assessing the
coordination spheres of dissolved transition metals.

■ INTRODUCTION
Understanding and preventing degradation in lithium-ion cells is
vital to extending their lifetimes and increasing their
applications. There are various causes of cell degradation, but
one mechanism is the dissolution of transition metal ions from
cathodematerials (e.g., Li[NixMnyCo1−x−y]O2 orNMC) into the
electrolyte solution, followed by the deposition of those metal
ions at the anode.1−6 Althoughmetal dissolution causes negative
effects at the positive electrode due to the loss of active material
and reconstruction of the cathode surface, the majority of
transition metal-related capacity losses from NMC and similar
cathodematerials arise frommetal deposition and reaction at the
negative electrode.7−13 Once deposited at the anode, transition
metals disrupt the solid electrolyte interphase (SEI), induce
further electrolyte decomposition, consume cyclable lithium,
and contribute to SEI thickening (with varying severity).7−30

The extent of dissolution from NMC, LiMn2O4, and
LiNi0.5Mn1.5O4, ex situ (e.g., from cathode powders stored in
electrolyte solutions) or in cells, varies widely depending on
factors, including storage time,9,14,31−33 cycle number,33−39

electrolyte composition,7,34,40−49 use of cathode coat-
ings,37,50−56 upper cutoff potential,8,12,13,29,36,38,40,44,57−61 and
temperature.9,12,31,33,38,57

Dissolved transition metals in electrolyte solutions can be
quantified in several ways. The two most commonly used
methods are inductively coupled plasma optical emission
spectroscopy (ICP-OES)14,31,33,38,40,62−64 and ICP mass
spectrometry (ICP-MS),23,46−48,65−69 while ion chromatogra-
phy,61,70−72 total reflection X-ray fluorescence,73−75 and ultra-
violet−visible spectroscopy62,63,76−78 have also been applied.
Electrochemical methods may also be used; differential pulse
polarography experiments34,79 and electrodeposition onto a
rotating ring disk electrode65 have been used to quantify Mn2+
dissolved from LiMn2O4.
The above methods provide precise quantification of the

metal concentration in solution; however, most of these destroy
or alter the sample, either because the measurement itself is
destructive or because chemical agents are added during sample
preparation. By contrast, nuclear magnetic resonance (NMR)
spectroscopy is a nondestructive technique that has been used to

Received: February 28, 2023
Revised: April 20, 2023
Published: May 16, 2023

Articlepubs.acs.org/JPCC

© 2023 The Authors. Published by
American Chemical Society

9509
https://doi.org/10.1021/acs.jpcc.3c01396
J. Phys. Chem. C 2023, 127, 9509−9521

https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Jennifer+P.+Allen"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf
https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Christopher+A.+O%E2%80%99Keefe"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf
https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Clare+P.+Grey"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf
https://pubs.acs.org/action/showCitFormats?doi=10.1021/acs.jpcc.3c01396&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?goto=articleMetrics&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?goto=recommendations&?ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?goto=supporting-info&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=abs1&ref=pdf
https://pubs.acs.org/toc/jpccck/127/20?ref=pdf
https://pubs.acs.org/toc/jpccck/127/20?ref=pdf
https://pubs.acs.org/toc/jpccck/127/20?ref=pdf
https://pubs.acs.org/toc/jpccck/127/20?ref=pdf
pubs.acs.org/JPCC?ref=pdf
https://pubs.acs.org?ref=pdf
https://pubs.acs.org?ref=pdf
https://doi.org/10.1021/acs.jpcc.3c01396?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://pubs.acs.org/JPCC?ref=pdf
https://pubs.acs.org/JPCC?ref=pdf
https://creativecommons.org/licenses/by/4.0/
https://creativecommons.org/licenses/by/4.0/
https://acsopenscience.org/open-access/licensing-options/


study lithium-ion cells because of its chemical specificity and
ability to provide information about both structure and
dynamics. NMR-active nuclei present in most lithium-ion cells
include 1H, 7Li, 13C, 17O, 19F, and 31P, among others. Solid-state
NMR has been used to study the electrode materials80−86 and
electrode−electrolyte interfaces,84,87−94 while solution NMR
has been used to study the electrolyte decomposition
products,95−101 transport properties,102−110 and solvation
structure.109,111−116 In situ and operando NMR experiments
have even been developed to probe chemical and electro-
chemical processes occurring in custom cells.82−86,105,110,117−119

Although deuterated solvents may be added to electrolytes for
solution NMR (irreversibly altering the sample and complicat-
ing potential operando analysis if deuterated electrolytes are not
available), this is not strictly necessary as these solvents may be
incorporated instead by using a solvent capillary or coaxial tube.
Because dissolved transition metals are paramagnetic, with

very rapid nuclear relaxation rates,80,120 NMR is not well suited
for the direct (e.g., 61Ni, 55Mn, 59Co) measurement of transition
metal dissolution and deposition. However, the magnetic
properties of other nuclei in the same sample are affected by
the presence of paramagnetic species, and NMR experiments
focusing on these other nuclides can reveal information about
the metals, including their oxidation state and coordination
environment. A key effect of paramagnetic species on NMR
measurement is relaxation enhancement, where the unpaired
electrons of the paramagnetic species create fluctuating
magnetic fields that drive efficient relaxation of nearby
nuclei.121−124 Relaxation times in both the longitudinal
dimension (T1, along the applied magnetic field B0) and
transverse dimension (T2, perpendicular to B0) are affected by
this interaction. Critically, the relaxation enhancement is
proportional to the concentration of paramagnetic species,121

so measurement of the NMR relaxation rate should enable
quantification of the dissolved metals. NMR field-cycling
relaxometry has recently been used to quantify dissolved Mn2+
in wine, an example of an application of the method to an
“electrolyte” containing multiple dissolved components.125 The
properties and equations governing paramagnetic relaxation
enhancement are described in detail in the Discussion section.
If nondestructive quantification is possible with NMR

relaxometry, this would not only preserve samples for later
analysis but also facilitate operando metal quantification with
NMR.Operando quantification of metal dissolution in a lithium-
ion cell has been achieved with ICP-MS coupled to an
electroanalytical flow cell,68 but this method is invasive,
requiring the electrolyte to be removed from the cell; thus, the
effects of electrolyte degradation and transitionmetal deposition
on cell performance are not captured. The use of relaxation-
weighted magnetic resonance imaging (MRI) could be used not
only to noninvasively quantify metal dissolution but also to
visualize the distribution of dissolved transition metals in a cell,
by mapping relaxation rates across the electrolyte volume
(where faster relaxation rates indicate larger metal concen-
trations). Such work has already been successfully performed to
examine Cu2+ electrodissolution into an aqueous Na2SO4
electrolyte solution.126

This work analyses the relaxation rates of electrolyte solutions
comprising LiPF6, carbonate solvents, and μM−mM quantities
of Ni2+, Mn2+, Co2+ (which may dissolve from NMC cathodes),
or Cu2+ (which may dissolve from copper current collectors), in
order to establish whether relaxometry provides a viable method
to quantify metal dissolution. This work follows from our

previous studies: in the first, we explored the use of bulk
magnetic susceptibility shifts to identify the oxidation states and
concentrations of dissolved paramagnetic ions.127 In the second,
we examined the line broadening induced by paramagnetic ions
in pristine and degraded battery electrolytes,128 describing
methods to mitigate this. Here, we analyze relaxation
phenomena in greater detail, measuring and analyzing both
transverse and longitudinal relaxation rates; we show that they
are highly sensitive to the presence of Mn2+, especially with 19F
and 1H measurements. Storage of LiMn2O4 powder with the
electrolyte solution at ∼20 °C shows that Mn(TFSI)2 is indeed
representative of Mn2+ dissolved from cathode materials, and
metal quantification was successful. However, the quantification
was far less accurate in a similar sample that had been stored at
60 °C, indicating that the species produced during the thermal
degradation processes may change the transition metal
coordination sphere and thereby reduce the applicability of
the NMR calibration data acquired with the pristine electrolyte
solutions. While potential operando applications face some
complications (outlined in this work), ex situ relaxometry may
be a valuable tool to nondestructively quantify dissolved metals
in battery electrolyte solutions. Notably, the dependence of
relaxation rates on metal solvation suggests that NMR
relaxometry may also be applied to probe the coordination of
dissolved metals to electrolyte species.

■ METHODS
Preparation of Electrolyte Solutions. Electrolyte sol-

utions comprised 1 M LiPF6 in 3:7 ethylene carbonate (EC)/
ethyl methyl carbonate (EMC) (v/v), a standard composition
that was sourced premixed (soulbrain MI PuriEL R&D 280).
Trifluoromethanesulfonimide (TFSI) salts were used to
simulate dissolved transition metals and were dried under
vacuum at 100 °C before use: Mn(TFSI)2 (Tokyo Chemical
Industry UK Ltd., >97.0% and Solvionic, 99.5%), Co(TFSI)2
(Alfa Aesar, ≥95.0%), Ni(TFSI)2 (Alfa Aesar, ≥97%), and
Cu(TFSI)2 (purchased as the hydrate, Sigma-Aldrich).

NMR Measurements of Electrolyte Solutions. NMR
relaxation measurements were performed at∼25 °C on a Bruker
Avance III HD 300 MHz spectrometer using a Bruker double-
channelMicWB40 probe.T1 measurements were acquired using
the inversion recovery pulse sequence; T2 measurements were
acquired using the Carr−Purcell−Meiboom−Gill (CPMG)
pulse sequence129,130 with echo spacings of τ = 2 ms (with the
exception of the 19FT2 measurement of 8.0 mMMn2+, where τ =
1 ms was used, due to very rapid relaxation). NMR spectra were
acquired using a Bruker Avance III HD 500 MHz spectrometer
equipped with a broadband observe (BBO) probe; NMR tubes
contained sealed C6D6 capillaries for field locking. In all cases,
NMR tubes were filled in an argon glovebox and sealed with J-
Young valves or with poly(tetrafluoroethylene) tape over the
cap. Measurements were conducted shortly after solution
preparation, and no significant changes in relaxation rates
were detected after some solutions were stored outside the
glovebox for ∼4 days.

LiMn2O4 Storage Experiment. To study Mn dissolution
from electrode materials, 3 g LiMn2O4 was combined with 7 mL
of the electrolyte solution and stored in an aluminum bottle
under argon for 88 days at ∼20 °C or 77 days at 60 °C. The
solution was then centrifuged and the supernatant was analyzed
with NMR and ICP-OES. ICP-OES samples were prepared via
the addition of trace metal grade nitric acid, and measurements

The Journal of Physical Chemistry C pubs.acs.org/JPCC Article

https://doi.org/10.1021/acs.jpcc.3c01396
J. Phys. Chem. C 2023, 127, 9509−9521

9510

pubs.acs.org/JPCC?ref=pdf
https://doi.org/10.1021/acs.jpcc.3c01396?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as


were carried out using an iCAP 7400 Duo ICP-OES Analyzer
(Thermo Fisher Scientific).

■ RESULTS

Figure 1 shows diamagnetic 7Li, 31P, and 19F NMR spectra of
LiPF6/EC/EMC solutions and relaxation measurements of

solutions containing 0−8 mM dissolved Mn2+, Ni2+, and Co2+.
19F measurements are also shown for solutions containing Cu2+.
Relaxation time constants are presented as relaxation rates in s−1,
referred to as R1 (1/T1) and R2 (1/T2). An expanded view of the
7Li and 31P relaxation is provided in the Supporting Information
(Figure S1). In all cases, the relaxation rates increase with the

Figure 1. (a−c) 7Li, 31P, and 19F representative NMR spectra of diamagnetic 1 M LiPF6 in 3:7 EC/EMC (v/v) and (d−f) longitudinal and (g−i)
transverse relaxation rates of electrolyte solutions containing dissolved Mn(TFSI)2, Cu(TFSI)2 (19F only), Ni(TFSI)2, or Co(TFSI)2. Only the
spectral region showing the PF6− is shown in the 31P and19F spectra; the observed multiplets arise from the 31P−19F J-coupling. Relaxation rates of
solutions containing Cu(TFSI)2, Ni(TFSI)2, andCo(TFSI)2 are plotted on the left y axes, while relaxation rates of solutions containingMn(TFSI)2 are
plotted on the right y axes, as indicated by the arrows in panel (d). Error bars at 1 mM indicate the standard deviation of three measurements on the
sample; they are difficult to visualize at this scale, but all 20 are <3%. The asterisk at 8 mMMn2+ in panel (i) indicates the use of a reduced echo spacing
of τ = 1 ms due to very fast relaxation. An expanded view of the 7Li and 31P relaxation data in panels (d), (e), (g), and (h) is provided in the Supporting
Information (Figure S1).

Figure 2. (a) Representative 1H NMR spectrum of diamagnetic 1 M LiPF6 in 3:7 EC/EMC (v/v) and (b−e) longitudinal and (f−i) transverse
relaxation rates of electrolyte solutions containing dissolved Mn(TFSI)2, Cu(TFSI)2, Ni(TFSI)2, or Co(TFSI)2. Relaxation rates of solutions
containing Mn(TFSI)2 are plotted on the right y axes. The multiple relaxation rates arise from the different 1H environments in the solvent system,
indicated in panel (a). Error bars at 1 mM indicate the standard deviation of three measurements on the sample; while difficult to visualize at this scale,
all 32 are <6%.

The Journal of Physical Chemistry C pubs.acs.org/JPCC Article

https://doi.org/10.1021/acs.jpcc.3c01396
J. Phys. Chem. C 2023, 127, 9509−9521

9511

https://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.3c01396/suppl_file/jp3c01396_si_001.pdf
https://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.3c01396/suppl_file/jp3c01396_si_001.pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig1&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig1&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig1&ref=pdf
https://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.3c01396/suppl_file/jp3c01396_si_001.pdf
https://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.3c01396/suppl_file/jp3c01396_si_001.pdf
https://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.3c01396/suppl_file/jp3c01396_si_001.pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig1&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig2&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig2&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig2&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig2&ref=pdf
pubs.acs.org/JPCC?ref=pdf
https://doi.org/10.1021/acs.jpcc.3c01396?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as


transition metal concentration. Generally, the relaxation rates
follow the trend 19F > 31P > 7Li. Notably, relaxation rates in
Mn2+-containing samples are 1−2 orders of magnitude faster
than those in Cu2+-, Ni2+-, or Co2+-containing samples. Linear
regression analysis shows that better fits are yielded for data with
larger relaxation changes: the only datasets with R2 < 0.99 are
those where very little change in relaxation is observed, namely,
results from 7Li NMR and results fromCo2+-containing samples.
The relationship between gradient and R2 for each nucleus is
shown in Figure S2.
Figure 2 shows 1H relaxation rates of electrolyte solutions

containing added transition metal ions. The four longitudinal
and transverse relaxation rates correspond to the four 1H
environments in the solvent system, indicated in Figure 2a. The
1H relaxation measurements show linearly increasing relaxation
rates, with Mn2+ inducing the greatest change. Among the three
EMC environments, the slowest-relaxing 1H environment is the
CH3 of the ethyl group (Figure 2e,i), which shows considerably
slower relaxation rates than the ethyl CH2 (Figure 2c,g) and the
methyl group (Figure 2d,h). Linear regression analysis of the 1H
data shows that it is mainly Co2+-containing samples that yield
poorer fits, while among the 24 Ni2+, Cu2+, and Mn2+ datasets,
the smallest R2 value is 0.986. The relationship between gradient
and R2 is shown in Figure S2, which also contains data for 7Li,
19F, and 31P relaxation.
Figure 3 shows 19F and 1H relaxation measurements of

electrolyte solutions containing both Mn2+ (0−4 mM) and Ni2+
(0−8 mM) ions. This experiment was performed to assess the

suitability of the relaxometry method to determine whether
concentrations of multiple metals can be detected in solution.
While some differences are visible between samples containing
different Ni2+ concentrations, such differences are small, and the
magnitude of relaxation rates are not always in the anticipated
order of increasing Ni2+ concentration (see, for example, the EC
transverse relaxation at the highest Mn2+ concentration).
Figure 4 shows 19F and 1H relaxation measurements of

electrolyte solutions that contain very low concentrations of
Mn2+ to estimate the method’s limit of detection (LoD). The
measurements were performed at 0, 0.001, 0.005, 0.010, 0.050,
0.100, and 0.500 mM. (Although only 0−0.1 mM is shown in
Figure 4, the lines of best fit include the 0.5 mM point, and the
full 0−0.5 mM scale is shown in Figure S3.) These measure-
ments show that the relaxation enhancement remains linear even
at very low metal concentrations and that the method is highly
sensitive to Mn2+. The 19F and 1H relaxation rates at 0, 0.001,
and 0.005 mM Mn2+ are listed in Table S1. With both the 5σ
criterion and the 5% error criterion, the LoD of the NMR
relaxometry method is on the order of 0.001−0.005 mM (the
limit for each of the 10 relaxation rates differs slightly).
To determine whether these Mn(TFSI)2 results can be

applied to Mn dissolved from battery materials, LiMn2O4
powder was soaked in the electrolyte solution and stored
under argon at either∼20 °C for 88 days or at 60 °C for 77 days.
Figure 5 compares the estimates for quantities of dissolved
metals obtained via 19F relaxation, 1H relaxation, and by ICP-
OES. Metals were quantified by relaxometry by using the linear

Figure 3. (a) 19F and (b) 1H longitudinal and transverse relaxation rates of 1 M LiPF6 in 3:7 EC/EMC (v/v) electrolyte solutions containing both
dissolved Mn(TFSI)2 (concentrations shown on the x axis) and Ni(TFSI)2 (concentrations indicated by the color of the points). The multiple
relaxation rates in the 1H NMR arise from the different 1H environments in the solvent system.

The Journal of Physical Chemistry C pubs.acs.org/JPCC Article

https://doi.org/10.1021/acs.jpcc.3c01396
J. Phys. Chem. C 2023, 127, 9509−9521

9512

https://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.3c01396/suppl_file/jp3c01396_si_001.pdf
https://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.3c01396/suppl_file/jp3c01396_si_001.pdf
https://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.3c01396/suppl_file/jp3c01396_si_001.pdf
https://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.3c01396/suppl_file/jp3c01396_si_001.pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig3&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig3&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig3&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig3&ref=pdf
pubs.acs.org/JPCC?ref=pdf
https://doi.org/10.1021/acs.jpcc.3c01396?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as


fits from Figure 4. The sample stored at 60 °C was also diluted
5×with pristine electrolyte to determine whether more accurate
estimates of Mn2+ concentration could be obtained from more
dilute solutions, and the NMR results were scaled by 5× for
direct comparison with the results obtained from the undiluted
sample. Six months later, two additional samples were prepared;

these samples were analyzed 9 months after the calibration
dataset was measured, and the results are discussed in the
Supporting Information (Figure S4).
For the sample stored at ∼20 °C for 88 days, the NMR

estimates of Mn concentration are a good match with the ICP-
OES measurement. However, for the 60 °C sample, all NMR

Figure 4. (a) 19F and (b) 1H longitudinal and transverse relaxation rates of 1 M LiPF6 in 3:7 EC/EMC (v/v) electrolyte solutions containing small
amounts of dissolved Mn(TFSI)2 to determine the limit of detection of the method. The multiple relaxation rates in the 1H NMR arise from the
different 1H environments in the solvent system.

Figure 5. EstimatedMn concentrations after (a)∼20 °C and (b, c) 60 °C storage of LiMn2O4 with 1 M LiPF6 in 3:7 EC/EMC (v/v), calculated from
19F and 1H longitudinal and transverse relaxation rates. In panel (c), the 60 °C sample was diluted 5× with the pristine electrolyte solution, and the
resultingNMR concentrations were scaled by 5× for direct comparison with the results in panel (b). Black bars indicate the concentrationmeasured by
ICP-OES, with error bars indicating the standard deviation of three samples.

The Journal of Physical Chemistry C pubs.acs.org/JPCC Article

https://doi.org/10.1021/acs.jpcc.3c01396
J. Phys. Chem. C 2023, 127, 9509−9521

9513

https://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.3c01396/suppl_file/jp3c01396_si_001.pdf
https://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.3c01396/suppl_file/jp3c01396_si_001.pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig4&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig4&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig4&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig4&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig5&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig5&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig5&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?fig=fig5&ref=pdf
pubs.acs.org/JPCC?ref=pdf
https://doi.org/10.1021/acs.jpcc.3c01396?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as


estimates are considerably smaller than the ICP-OES measure-
ment. The 60 °C sample contains almost 2 orders of magnitude
more Mn than the 20 °C sample (4.67 ± 0.05 vs 0.066 ± 0.003
mM, respectively, from ICP-OES), and after dilution of the 60
°C sample with pristine electrolyte, theNMR estimates aremore
consistent with the ICP-OES result, although the concentration
is still underestimated by NMR. Among the different NMR
estimates for Mn concentration, the least accurate values
(smallest estimated concentrations) are obtained from the 19F
PF6− relaxation rates, and the most accurate values are obtained
when the concentration is estimated from the 1H EMC ethyl
CH3 relaxation rates. The source of these deviations is addressed
in the Discussion section.

■ DISCUSSION
In this work, the Solomon−Bloembergen−Morgan
model120−123,131 of relaxation is adopted to provide a framework
within which to discuss our results. Equations 1 and 2 describe
the relaxation rates of nuclei bound to paramagnetic ions (R1M
andR2M or 1/T1M and 1/T2M, respectively), where the first terms
describe through-space dipolar coupling of the nuclear and
electron spins120−122 and the second terms describe the
isotropic contact interaction.120,121,123 The paramagnetic
relaxation enhancement is strongly affected by the ion−nucleus
distance (1/r6) and the electron spin (S(S + 1)). Other values in
eqs 1 and 2 include the permeability of vacuum (μ0), nuclear
gyromagnetic ratio (γI), electron spin g-factor (ge), Bohr
magneton (μB), Larmor frequencies for the nuclear spin (ωI)
and electron spin (ωS), the hyperfine interaction constant (A/
ℏ), and correlation times for the dipolar (τcdip) and contact
(τccon) terms. The timescales of the fluctuating magnetic fields
are quantified by the correlation times, which differ depending
on the mechanism of coupling between the fluctuating field and
the nuclear spin. For the dipolar term, τcdip is determined by the
molecular rotation (τr), electronic relaxation (τe), and chemical
exchange (τM) correlation times, as shown in eq 3, while for the
isotropic contact term, τccon is determined by τe and τM, as shown
in eq 4.121

=
+

+

+
+

+ +

+

i
k
jjj y

{
zzz

i
k
jjjjj

y
{
zzzzz

i
k
jjjjj

y
{
zzzzz

R
g S S

r

S S A

2
15 4

( 1) 3
1 ( )

7

1 ( )
2
3

( 1)

1 ( )

1M
0

2
I
2

e
2

B
2

6
c
dip

I
2

c
2 dip

c
dip

S
2

c
2 dip

2

2

c
con

S
2

c
2 con

(1)

=
+

+
+

+
+

+ +

+
+

i
k
jjj y

{
zzz

i
k
jjjjj

y
{
zzzzz

i
k
jjjjj

y
{
zzzzz

R
g S S

r

S S A

1
15 4

( 1)
4

3
1 ( )

13

1 ( )
1
3

( 1)

1 ( )S

2M
0

2
I
2

e
2

B
2

6 c
dip c

dip

I
2

c
2 dip

c
dip

S
2

c
2 dip

2

2

c
con c

con

2
c
2 con

(2)

= + +( )c
1 dip

r
1

e
1

M
1 (3)

= +( )c
1 con

e
1

M
1

(4)

The above equations describe the relaxation of the paramagnetic
complex; however, in dilute solutions, most observed NMR
nuclei are not in ions or molecules bound to paramagnetic ions.
We must therefore take into account the probability of a nuclide
being adjacent to a paramagnetic ion and thus the probability
that it will undergo the relaxation processes described in eqs 1
and 2. Equations 5 and 6 show the paramagnetic relaxation
enhancement R1p and R2p, i.e., the difference between the
observed relaxation rates of a paramagnetic sample and its
diamagnetic analogue (or R1 − R1d and R2 − R2d).

121,132 The
relaxation enhancement is proportional to fM, the molar fraction
of nuclei that are bound to paramagnetic metal ions. (There is
also a dependence on chemical exchange, with timescale τM,
between the free species and the complex where the species is
bound to the paramagnetic center; additionally, the transverse
relaxation has a term that depends on the hyperfine shift ΔωM.)
The measured relaxation rates can therefore be related to eqs 1
and 2, which are derived for a defined complex with a finite
lifetime (hence, paramagnetic relaxation effects due to free
diffusion are ignored).

= =
+

R R R f
R

1
(1/ )1p 1 1d M

1M M (5)

= = + +
+ +

R R R f
R R

R
( (1/ )) ( )

( (1/ )) ( )2p 2 2d M
2M 2M M M

2

M 2M M
2

M M
2

(6)

Equations 1−6 show that the effect of dissolved transitionmetals
on the relaxation rate is highly specific to the system, with a
dependence on molecular motion (rotation and exchange),
metal−nucleus distance, and the degree of transition metal
coordination, among other factors.121 If the metal concentration
is already known, the relaxometry result does not necessarily
provide a clear indication of which oxidation state is dissolved;
instead, a reliable calibration is required to interpret the
relaxometry results. While differences in relaxometry results
could indicate the dissolution of one oxidation state vs another, it
could also indicate changes to the metal solvation shell.
Although the interpretation of relaxometry results is by no
means straightforward, given the multiple correlation times and
interactions, we attempt to draw simple trends from the data,
which will inevitably require a number of assumptions that we,
when possible, explore.
Calibration curves of the NMR response to the presence of

various transition metals are shown in Figures 1 and 2. In these
figures, the limit of detection for the relaxometry method is
observed to vary for each metal, nucleus, and environment. The
method is most sensitive to paramagnetic species with more
unpaired electrons (larger S) and slower electronic relaxation
rates (longer τe). Typical Mn2+ electronic relaxation rates are
one or more orders of magnitude slower than those of Cu2+,
Ni2+, or Co2+.121 The slower electron spin relaxation for Mn2+
arises from the lack of orbital angular momentum of the state
with symmetry A, and this long τe results in Mn2+ inducing
especially rapid nuclear relaxation.120 The relaxation enhance-
ment from Mn2+ (3d5) is also expected to be stronger than that
of Cu2+ (3d9), Ni2+ (3d8), and Co2+ (3d7) due to the greater
number of unpaired electrons in Mn2+, which yields a
significantly larger S(S + 1) term.
Nuclei that show a larger response to the metal concentration

are likely in environments that are, on average, closer to the
paramagnetic centers. The NMR nucleus may be closer to the

The Journal of Physical Chemistry C pubs.acs.org/JPCC Article

https://doi.org/10.1021/acs.jpcc.3c01396
J. Phys. Chem. C 2023, 127, 9509−9521

9514

pubs.acs.org/JPCC?ref=pdf
https://doi.org/10.1021/acs.jpcc.3c01396?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as


metal binding site, as the dipolar relaxation enhancement of
dissolved metals occurs through space with a 1/r6 dependence
(eqs 1 and 2). Alternately, the fraction of the species coordinated
to the transition metal may be larger (eqs 5 and 6). The 7Li, 31P,
and 19F NMR results in Figure 1 indicate, reasonably, that the
transition metal cations are found much closer to PF6− than to
Li+, presumably due to electrostatic interactions. The larger
relaxation effect on 19F vs 31P nuclei is explained by the larger γI
of 19F and also by the PF6− structure, as P is surrounded by, and
less accessible than, electron-rich F atoms. While paramagnetic
relaxation enhancement applies to all nuclides in Figure 1, 19F
NMR is therefore the most suitable of these for the
measurement of dissolved transition metals, particularly Mn2+.
As a result, the relaxationmethodmay be readily applied to other
electrolyte solutions containing fluorinated salts or solvents
because they are observable with 19F NMR and should, in many
cases, experience some electrostatic attraction to metal cations.
7Li NMR is least suitable for the measurement of dissolved
transition metals due to cation repulsion. Although 7Li
relaxation of Mn2+-containing samples shows strong linearity
with metal concentration, we note that quadrupolar relaxation
mechanisms may become increasingly more important at low
metal concentrations, particularly for samples containing Ni2+
and Co2+, potentially resulting in nonlinear behaviour.
The 1H relaxation measurements (Figure 2) show the same

general behavior as the 7Li, 31P, and 19F relaxationmeasurements
(Figure 1). As EMC has three 1H environments, the differences
among the relaxation rates reflect the relative distances between
each environment and the coordinated metal ion (from the 1/r6
dependence of dipolar relaxation in eqs 1 and 2, although it is
noted that binding to the metal ions is likely highly dynamic).
Transition metal coordination to EMC occurs at the carbonyl
oxygen: this is consistent with the observation of the slowest
relaxation arising from the ethyl CH3 (Figure 2e,i) and the
observation that the ethyl CH2 (Figure 2c,g) relaxes slightly
faster than the methyl group (Figure 2d,h), since the ethyl CH2
hydrogens are, on average, closer to the C�O. (In the
diamagnetic electrolyte solution, the three EMC 1H environ-
ments do not show equal relaxation rates; however, the trends
stated here also apply to the relaxation enhancement from the
diamagnetic baseline�the gradients of the lines of best fit in
Figure 2 follow the order EMC ethyl CH2 > EMC methyl >
EMC ethyl CH3.) These results echo the finding from a
computational study, which suggested that Mn2+ would
coordinate at the EMC carbonyl oxygen.133 These results are
also consistent with theoretical and experimental studies of Li+
solvation, which show that metal coordination occurs
preferentially at C�O for EC and linear carbonates.112,134−139

For all transition metal solutions and all nuclides, R2 is larger
than R1. But whereas R2 is ∼1−2 times larger than R1 for 1H
relaxation in all solutions and for 19F relaxation in Co2+-, Ni2+-,
and Cu2+ containing solutions, R2 is an order of magnitude larger
than R1 for 19F relaxation in Mn2+-containing solutions (Figures
1 and 2). This is likely due to the electronic relaxation time of
Mn2+, which is slower than the electronic relaxation times of the
other three metals.121 Dipolar relaxation processes for Mn2+ are
therefore far more likely to be limited by a different correlation
time. This would be relevant if, for example, there were multiple
relaxation processes occurring; these could affect the R1 and R2
terms differently due to a motional component, which would
only become apparent when the electronic relaxation time is
sufficiently slow. Another potential reason that R2 may be much
larger than R1 is the involvement of a contact term. The contact

term in R1M depends on the spectral density at the Larmor
frequency of the unpaired electron spin, ωS, and the correlation
time for the contact interaction, τccon (eq 1). Thus, in Mn2+-
containing solutions, the R1M contact term may approach 0 due
to the large Larmor frequency of the unpaired electron spin and
the slow electronic relaxation of the Mn2+ ion. By contrast, the
R2M contact term contains a frequency-independent component.
If the R2M contact term is large, and the R1M contact term is
negligible, then R2 can become much larger than R1.

123 We also
note that the exchange times may not be equal for all metals, as
the interaction strengths with electrolyte components may
differ, and this may also affect the observed relationship between
R2 and R1. Unraveling the different mechanistic contributions to
exchange processes may require measurements at different
temperatures and magnetic field strengths, and such efforts are
beyond the scope of this work.
In Figure 3, although the R1 measurements do show some

differences between the samples containing different amounts of
Ni2+, the difference between a sample containing 2 and 8 mM
Ni2+ is too small to be quantified via R1, and even falls within the
error of R2 measurements. The relaxation rates should be
additive at these low metal concentrations; for a solution
containing both Ni2+ and Mn2+, R1 = R1d + R1p,Ni + R1p,Mn. That
is, the total relaxation is expected to comprise a diamagnetic
relaxation component (small), a component for the para-
magnetic relaxation induced by Ni2+ (small), and a component
for the paramagnetic relaxation induced byMn2+ (large). For the
samples used in this work, relaxation rates alone are not
sufficient to distinguish the concentrations of Ni2+ and Mn2+
when both are in solution, due to the much larger effect of Mn2+.
However, the low-concentration Mn2+ relaxation measurements
in Figure 4 show the potential sensitivity of this method toward
measuring realistic concentrations of dissolved Mn2+. Indeed,
this is shown in Figure 5a, where the quantification of Mn
dissolved from LiMn2O4 in the pristine electrolyte is a good
match to the 0.066 ± 0.003 mM detected by ICP-OES. This
suggests that the Mn dissolved from LiMn2O4 at ∼20 °C exists
as Mn2+. Mn3+ has a different S and τe than Mn2+,121 in addition
to likely having a different binding affinity for the electrolyte
components; therefore, different R1 and R2 values would result if
a significant fraction of dissolved Mn were present as Mn3+,
likely requiring further study to explore Mn3+ relaxation
phenomena. It is also promising that the calibration based on
Mn(TFSI)2 could be successfully applied to a sample containing
Mn dissolved from LiMn2O4, suggesting that the TFSI− anion
did not affect the calibration. While M(TFSI)2 salts were used in
this work due to their high solubility and ready availability, we
anticipate that any model compound in which the paramagnetic
metal does not form a long-lived ion pair with the counterion
could be used to quantify dissolution in samples retaining the
same paramagnetic metal solvation shell as the calibration set.
After storage at 60 °C, the relaxation measurements provided

a poor estimate of the actualMn concentration (Figure 5b). This
is not due to any nonlinear relaxation behavior at large Mn
concentrations, as the 4.67 ± 0.05 mM concentration is well
within the linear behavior shown in Figures 1 and 2 for 0−8 mM
Mn2+. Although higher temperatures drive changes in relaxation
behavior due to shortening of rotational and chemical exchange
times and changes in electronic relaxation times, the 60 °C
sample was cooled to ambient temperature before the relaxation
measurements were performed; temperature is therefore not the
cause of this discrepancy. While we should consider whether the
poor match between relaxometry and ICP-OES results for the

The Journal of Physical Chemistry C pubs.acs.org/JPCC Article

https://doi.org/10.1021/acs.jpcc.3c01396
J. Phys. Chem. C 2023, 127, 9509−9521

9515

pubs.acs.org/JPCC?ref=pdf
https://doi.org/10.1021/acs.jpcc.3c01396?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as


60 °C sample occurred due toMn3+ dissolution, the results from
the ∼20 °C dissolution experiment show that Mn2+ is the
dissolution species. Furthermore, our previous analysis of the
high-temperature sample using NMR bulk magnetic suscepti-
bility shifts to determine the metal oxidation state confirmed the
presence of Mn2+ and not Mn3+ in the sample.127

The issue with relaxometry of the sample stored at 60 °Cmay
therefore not be related to the Mn concentration or oxidation
state but rather to the presence of degradation species in the
electrolyte solution. This hypothesis is now explored. First, as
shown in Figure 5c, the Mn concentration estimate was greatly
improved by diluting the sample 5× with pristine diamagnetic
electrolyte, i.e., the estimate was more accurate when
concentrations of degradation species were reduced by 5×.
The paramagnetic relaxation enhancement R1p and R2p are
directly proportional to fM, the molar fraction of nuclei bound to
paramagnetic species (eqs 5 and 6). The fraction of nuclei that
are bound to paramagnetic metal ions is a function of the
number of metal ions, the metal solvation number, and the total
number of nuclei in the sample. Equations 5 and 6 can be
rewritten as eqs 7 and 8, in the form y = mx + c.

=
+

+R
R

f R1
(1/ )1

1M M
M 1d

(7)

= + +
+ +

+R
R R

R
f R

( (1/ )) ( )
( (1/ )) ( )2
2M 2M M M

2

M 2M M
2

M M
2 M 2d

(8)

In the pristine electrolyte calibration solutions (Figures 1 and 2),
fM was increased via the metal concentration, while the solution
composition remained the same. At these relatively low
concentrations, the strength of binding of Mn2+ to each of the
electrolyte components should not change, and the nature of the
Mn2+ complexes and τM values should also remain unchanged.
That is, in the pristine solutions, the only reason for a change in
the relaxation rate is a change in fM, specifically arising from a
differentMn2+ concentration. However, in the heated electrolyte
solution (Figure 5b), new degradation species were generated,
with potentially different binding affinities for Mn2+. The 1H EC
R1 and R2 values predicted a Mn concentration of 2.58 ± 0.07
mM, while ICP-OES revealed an actual concentration of 4.67 ±
0.05 mM (predictions based on the relaxation rates of PF6− and
EMC were also inaccurate, with the least accurate estimates
arising from the 19F PF6− relaxation). Assuming, for simplicity, a
constant chemical exchange correlation time in the pristine and
degraded electrolyte solutions, the measured 1H EC R1 should
only change when a change in fM (the x variable in eqs 7 and 8)
occurs. In the case of the degraded electrolyte, based on the
measured 1H EC relaxation rates, fM,EC was small�not because
there were fewer Mn2+ ions in solution (as the calibration would
predict) but, we suggest, because there were fewer Mn2+ ions
bound to EC. It is possible that the relaxation measurement
predicts only 55% of the actual Mn concentration because the
other 45% of Mn ions that are bound to EC in the pristine
electrolyte solution are instead bound to another species in the
degraded solution (such as PO2F2−). This is consistent with our
previous work showing that the addition of different solvents to
electrolyte samples containing dissolved transition metals may
dramatically affect transverse relaxation enhancement of
electrolyte components, presumably by altering the metal
coordination shell.128 Preferential coordination of transition
metals by PF6− degradation species has also been previously
proposed by us128 and by others;72,140 upcoming work will also

explore transition metal coordination in detail using NMR and
electron paramagnetic resonance (EPR) spectroscopy. Theo-
retically, if the solvation shell surrounding the 4.67 mMMn (the
concentration present in the degraded electrolyte solution)
comprised 6 EC molecules, this would correspond to a total
displacement of 12.6 mM EC, likely by 12.6 mM of one or
several other species. This is not an unreasonable level of
electrolyte degradation: to generate 12.6 mM of fluorophos-
phate degradation species would require the decomposition of
only 1.3% of all LiPF6 in a solution of 1 M LiPF6 in 3:7 EC/
EMC. That the relaxation rates in Figure 5 predict, on average,
only 58% of the total Mn concentration measured by ICP-OES
is therefore consistent with the proposal that electrolyte
degradation species preferentially bind to Mn2+, reducing the
fraction of EC, EMC, and PF6− in the Mn2+ solvation shell.
Notably, this assumes that all change in the relaxation rate
derives from a change in the coordinated fraction of EC, and that
the effect of exchange is negligible. This smaller coordinated
fraction results in longer 1H EC, 1H EMC, and 19F PF6−

relaxation rates than those seen in pristine electrolytes with
similar paramagnetic metal ion concentrations, lessening the
applicability of the calibration dataset.
Although the metal quantification in degraded samples is

subject to inaccuracies arising from small changes in the metal
solvation shell, conversely, this indicates that NMR relaxometry
may be applied toward understanding the solvation shell in
samples with a constant metal concentration. Such an
application is common in the biochemical determination of
protein structures, where spin labels are attached to particular
protein sites, and the resulting differential relaxation enhance-
ment provides information about distances between spin labels
and other nuclei.141−143 The use of NMR relaxometry to
decipher metal coordination in battery electrolytes may offer
new insights into dissolution and deposition processes; while it
is beyond the scope of this work to analyze metal solvation in
detail here, such an analysis will be presented in upcoming work.
That the quantification of transition metals is less accurate

when degradation species affect the metal solvation shell is a
complicating factor to using the NMR method because
transition metal dissolution is inherently a degradation
mechanism�in particular, one that may be enhanced by the
acidification of the electrolyte solution40,64,144 and the release of
singlet oxygen,145 which reacts with electrolyte components.146

The idea that transition metal dissolution occurs in batteries in a
manner that leaves the electrolyte solution in pristine condition
is not realistic in traditional LiPF6/carbonate solutions. Hence,
metal quantification via relaxometry is likely most feasible in
systems where metal dissolution is substantial and electrolyte
degradation is minimal. Examples include cathode symmetric
cells, cells with high-voltage anodes and/or dissolution-prone
cathodes (especially if operated at moderate voltages, where
dissolution may outpace electrolyte degradation), and cells with
more thermally, chemically, and electrochemically stable
electrolyte solutions.
The results in Figure 5c also show that diluting the heat-

degraded sample with pristine electrolyte increases the
applicability of the pristine calibration data, returning the
electrolyte and the Mn2+ coordination shell to a state closer to
that found in the original calibration electrolyte. Similarly, if
both the pristine calibration solutions and the experimental
samples are manipulated to produce the same transition metal
coordination shell�such as by adding a compound that is
known to chelate the dissolved metals, and the compound is

The Journal of Physical Chemistry C pubs.acs.org/JPCC Article

https://doi.org/10.1021/acs.jpcc.3c01396
J. Phys. Chem. C 2023, 127, 9509−9521

9516

pubs.acs.org/JPCC?ref=pdf
https://doi.org/10.1021/acs.jpcc.3c01396?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as


probed by NMR in addition to the electrolyte components�
then it may be possible to apply the calibration to the degraded
experimental samples without issue. However, both of these
proposed adaptations of the method alter the electrolyte sample,
and diluting the samples with pristine electrolyte obviously
increases the minimum metal concentration required in the
original sample. These adaptations may therefore not be feasible
for metal quantification in operando NMR cells. Operando
quantification is also further complicated by the possibility of
multiple dissolved oxidation states (e.g., paramagnetic Mn2+ and
Mn3+ or paramagnetic Co2+ and undetectable diamagnetic
Co3+) or multiple dissolved metals (e.g., paramagnetic Fe2+ or
Fe3+ from the dissolution of stainless steel cell parts). Caution is
therefore needed in adapting the ex situ results presented here
for any operando work.

■ CONCLUSIONS
In this work, 7Li, 31P, 19F, and 1H NMR relaxation rates were
used to indirectly quantify the concentration of dissolved
transition metals in lithium-ion battery electrolyte solutions.
Calibrations with M(TFSI)2 salts showed that NMR relaxation
rates are proportional to the metal concentration and may be
used to determine the concentrations of dissolved paramagnetic
metals, with the Mn(TFSI)2 salt inducing the same relaxation
behavior as Mn2+ dissolved from LiMn2O4 at ∼20 °C. In our
solutions, 1H and 19F relaxation rates are more sensitive than 31P
and 7Li relaxation rates to metal concentration, and Mn2+
induces faster relaxation rates than Co2+, Ni2+, or Cu2+; hence,
the method is most sensitive to Mn2+. However, it is important
that the solution composition and metal oxidation state are
known and constant between the calibration and experimental
samples: changes in the transition metal solvation shell, which
may occur due to electrolyte degradation, impede the accuracy
of relaxometric quantification. Relaxation rates also contain
information about transition metal solvation, which may be
another promising application of the method. Understanding
transition metal dissolution behavior, including factors that
enhance dissolution, may permit optimization of strategies to
mitigate capacity losses induced by transition metal dissolu-
tion−migration−deposition processes.

■ ASSOCIATED CONTENT
*sı Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396.

Expanded view of 7Li and 31P relaxation; relationship
between determination coefficient and relaxivity in
Figures 1 and 2; limit of detection results with scale
extended to 0.5 mM Mn2+; tabulated relaxation rates of
samples containing 0, 0.001, and 0.005 mM Mn2+; and
discussion of second LiMn2O4 experiment (PDF)

■ AUTHOR INFORMATION
Corresponding Author

Clare P. Grey − Yusuf Hamied Department of Chemistry,
University of Cambridge, Cambridge CB2 1EW, U.K.; The
Faraday Institution, Didcot OX11 0RA, U.K.; orcid.org/
0000-0001-5572-192X; Email: cpg27@cam.ac.uk

Authors
Jennifer P. Allen − Yusuf Hamied Department of Chemistry,
University of Cambridge, Cambridge CB2 1EW, U.K.; The

Faraday Institution, Didcot OX11 0RA, U.K.; orcid.org/
0000-0002-9800-9382

Christopher A. O’Keefe − Yusuf Hamied Department of
Chemistry, University of Cambridge, Cambridge CB2 1EW,
U.K.; The Faraday Institution, Didcot OX11 0RA, U.K.

Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.jpcc.3c01396

Notes
The authors declare no competing financial interest.

■ ACKNOWLEDGMENTS
J.P.A. thanks Nigel Howard of the Yusuf Hamied Department of
Chemistry’s Microanalysis service for performing ICP-OES
measurements; Josef Granwehr, Conrad Szczuka, Evan Zhao,
and Zachary Ruff for helpful discussions; and the Natural
Sciences and Engineering Research Council of Canada and the
Royal Society for funding. This work was also funded by the
Faraday Institution via grant number FIRG001.

■ REFERENCES
(1) Li, W.; Song, B.; Manthiram, A. High-Voltage Positive Electrode
Materials for Lithium-Ion Batteries. Chem. Soc. Rev. 2017, 46, 3006−
3059.
(2) Xiao, B.; Sun, X. Surface and Subsurface Reactions of Lithium
Transition Metal Oxide Cathode Materials: An Overview of the
Fundamental Origins and Remedying Approaches. Adv. Energy Mater.
2018, 8, No. 1802057.
(3) Zhan, C.; Wu, T.; Lu, J.; Amine, K. Dissolution, Migration, and
Deposition of Transition Metal Ions in Li-Ion Batteries Exemplified by
Mn-Based Cathodes − a Critical Review. Energy Environ. Sci. 2018, 11,
243−257.
(4) Harris, O. C.; Lee, S. E.; Lees, C.; Tang, M. Review: Mechanisms
and Consequences of Chemical Cross-Talk in Advanced Li-Ion
Batteries. J. Phys. Energy 2020, 2, No. 032002.
(5) Li, T.; Yuan, X.-Z.; Zhang, L.; Song, D.; Shi, K.; Bock, C.
Degradation Mechanisms and Mitigation Strategies of Nickel-Rich
NMC-Based Lithium-Ion Batteries. Electrochem. Energy Rev. 2020, 3,
43−80.
(6) Jiang, M.; Danilov, D. L.; Eichel, R.-A.; Notten, P. H. L. A Review
of Degradation Mechanisms and Recent Achievements for Ni-Rich
Cathode-Based Li-Ion Batteries. Adv. Energy Mater. 2021, 11,
No. 2103005.
(7) Amine, K.; Chen, Z.; Zhang, Z.; Liu, J.; Lu, W.; Qin, Y.; Lu, J.;
Curtis, L.; Sun, Y.-K. Mechanism of Capacity Fade of MCMB/
Li1.1[Ni1/3Mn1/3Co1/3]0.9O2 Cell at Elevated Temperature and
Additives to Improve Its Cycle Life. J. Mater. Chem. 2011, 21,
17754−17759.
(8) Zheng, H.; Sun, Q.; Liu, G.; Song, X.; Battaglia, V. S. Correlation
between Dissolution Behavior and Electrochemical Cycling Perform-
ance for LiNi1/3Co1/3Mn1/3O2-Based Cells. J. Power Sources 2012, 207,
134−140.
(9) Pieczonka, N. P.W.; Liu, Z.; Lu, P.; Olson, K. L.; Moote, J.; Powell,
B. R.; Kim, J.-H. Understanding Transition-Metal Dissolution Behavior
in LiNi0.5Mn1.5O4 High-Voltage Spinel for Lithium Ion Batteries. J.
Phys. Chem. C 2013, 117, 15947−15957.
(10) Xiao, X.; Ahn, D.; Liu, Z.; Kim, J.-H.; Lu, P. Atomic Layer
Coating to Mitigate Capacity Fading Associated with Manganese
Dissolution in Lithium Ion Batteries. Electrochem. Commun. 2013, 32,
31−34.
(11) Zhan, C.; Lu, J.; Kropf, A. J.; Wu, T.; Jansen, A. N.; Sun, Y.-K.;
Qiu, X.; Amine, K. Mn(II) Deposition on Anodes and Its Effects on
Capacity Fade in Spinel Lithium Manganate−Carbon Systems. Nat.
Commun. 2013, 4, No. 2437.
(12) Buchberger, I.; Seidlmayer, S.; Pokharel, A.; Piana, M.;
Hattendorff, J.; Kudejova, P.; Gilles, R.; Gasteiger, H. A. Aging Analysis

The Journal of Physical Chemistry C pubs.acs.org/JPCC Article

https://doi.org/10.1021/acs.jpcc.3c01396
J. Phys. Chem. C 2023, 127, 9509−9521

9517

https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?goto=supporting-info
https://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.3c01396/suppl_file/jp3c01396_si_001.pdf
https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Clare+P.+Grey"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf
https://orcid.org/0000-0001-5572-192X
https://orcid.org/0000-0001-5572-192X
mailto:cpg27@cam.ac.uk
https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Jennifer+P.+Allen"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf
https://orcid.org/0000-0002-9800-9382
https://orcid.org/0000-0002-9800-9382
https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Christopher+A.+O%E2%80%99Keefe"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf
https://pubs.acs.org/doi/10.1021/acs.jpcc.3c01396?ref=pdf
https://doi.org/10.1039/C6CS00875E
https://doi.org/10.1039/C6CS00875E
https://doi.org/10.1002/aenm.201802057
https://doi.org/10.1002/aenm.201802057
https://doi.org/10.1002/aenm.201802057
https://doi.org/10.1039/C7EE03122J
https://doi.org/10.1039/C7EE03122J
https://doi.org/10.1039/C7EE03122J
https://doi.org/10.1088/2515-7655/ab8b68
https://doi.org/10.1088/2515-7655/ab8b68
https://doi.org/10.1088/2515-7655/ab8b68
https://doi.org/10.1007/s41918-019-00053-3
https://doi.org/10.1007/s41918-019-00053-3
https://doi.org/10.1002/aenm.202103005
https://doi.org/10.1002/aenm.202103005
https://doi.org/10.1002/aenm.202103005
https://doi.org/10.1039/C1JM11584G
https://doi.org/10.1039/C1JM11584G
https://doi.org/10.1039/C1JM11584G
https://doi.org/10.1016/j.jpowsour.2012.01.122
https://doi.org/10.1016/j.jpowsour.2012.01.122
https://doi.org/10.1016/j.jpowsour.2012.01.122
https://doi.org/10.1021/jp405158m?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/jp405158m?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1016/j.elecom.2013.03.030
https://doi.org/10.1016/j.elecom.2013.03.030
https://doi.org/10.1016/j.elecom.2013.03.030
https://doi.org/10.1038/ncomms3437
https://doi.org/10.1038/ncomms3437
https://doi.org/10.1149/2.0721514jes
pubs.acs.org/JPCC?ref=pdf
https://doi.org/10.1021/acs.jpcc.3c01396?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as


of Graphite/LiNi1/3Mn1/3Co1/3O2 Cells Using XRD, PGAA, and AC
Impedance. J. Electrochem. Soc. 2015, 162, A2737−A2746.
(13) Gilbert, J. A.; Shkrob, I. A.; Abraham, D. P. Transition Metal
Dissolution, Ion Migration, Electrocatalytic Reduction and Capacity
Loss in Lithium-Ion Full Cells. J. Electrochem. Soc. 2017, 164, A389−
A399.
(14) Aoshima, T.; Okahara, K.; Kiyohara, C.; Shizuka, K. Mechanisms
of Manganese Spinels Dissolution and Capacity Fade at High
Temperature. J. Power Sources 2001, 97−98, 377−380.
(15) Komaba, S.; Kumagai, N.; Kataoka, Y. Influence of Manganese-
(II), Cobalt(II), and Nickel(II) Additives in Electrolyte on Perform-
ance of Graphite Anode for Lithium-Ion Batteries. Electrochim. Acta
2002, 47, 1229−1239.
(16) Tsunekawa, H.; Satoshi Tanimoto, A.; Marubayashi, R.; Fujita,
M.; Kifune, K.; Sano,M. Capacity Fading of Graphite Electrodes Due to
the Deposition of Manganese Ions on Them in Li-Ion Batteries. J.
Electrochem. Soc. 2002, 149, A1326−A1331.
(17) Markovsky, B.; Rodkin, A.; Salitra, G.; Talyosef, Y.; Aurbach, D.;
Kim, H.-J. The Impact of Co2+ Ions in Solutions on the Performance of
LiCoO2, Li, and Lithiated Graphite Electrodes. J. Electrochem. Soc.
2004, 151, A1068−A1076.
(18) Delacourt, C.; Kwong, A.; Liu, X.; Qiao, R.; Yang, W. L.; Lu, P.;
Harris, S. J.; Srinivasan, V. Effect of Manganese Contamination on the
Solid-Electrolyte-Interphase Properties in Li-Ion Batteries. J. Electro-
chem. Soc. 2013, 160, A1099−A1107.
(19) Hongo, H.; Fujieda, S. Surface Degradation of Mixed LiMn2O4/
LiNiO2 Cathode Particles and Capacity Fade in Li-Ion Batteries
During Accelerated Calendar Life Test. ECS Meet. Abstr. 2013,
MA2013-02, 1057.
(20) Joshi, T.; Eom, K.; Yushin, G.; Fuller, T. F. Effects of Dissolved
Transition Metals on the Electrochemical Performance and SEI
Growth in Lithium-Ion Batteries. J. Electrochem. Soc. 2014, 161,
A1915−A1921.
(21) Xiao, X.; Liu, Z.; Baggetto, L.; Veith, G. M.; More, K. L.; Unocic,
R. R. Unraveling Manganese Dissolution/Deposition Mechanisms on
the Negative Electrode in Lithium Ion Batteries. Phys. Chem. Chem.
Phys. 2014, 16, 10398−10402.
(22) Shin, H.; Park, J.; Sastry, A. M.; Lu, W. Degradation of the Solid
Electrolyte Interphase Induced by the Deposition of Manganese Ions. J.
Power Sources 2015, 284, 416−427.
(23) Vissers, D. R.; Chen, Z.; Shao, Y.; Engelhard, M.; Das, U.;
Redfern, P.; Curtiss, L. A.; Pan, B.; Liu, J.; Amine, K. Role ofManganese
Deposition on Graphite in the Capacity Fading of Lithium Ion
Batteries. ACS Appl. Mater. Interfaces 2016, 8, 14244−14251.
(24) Cui, X.; Tang, F.; Li, C.; Zhang, Y.; Wang, P.; Feng, H.; Zhao, J.;
Li, F.; Li, S. ImprovingMnTolerance of Lithium-Ion Batteries by Using
Lithium Bis(Oxalato)Borate-Based Electrolyte. Electrochim. Acta 2017,
253, 291−301.
(25) Lee, Y. K.; Park, J.; Lu,W. AComprehensive Study ofManganese
Deposition and Side Reactions in Li-Ion Battery Electrodes. J.
Electrochem. Soc. 2017, 164, A2812−A2822.
(26) Solchenbach, S.; Hong, G.; Freiberg, A. T. S.; Jung, R.; Gasteiger,
H. A. Electrolyte and SEIDecomposition Reactions of TransitionMetal
Ions Investigated by On-Line Electrochemical Mass Spectrometry. J.
Electrochem. Soc. 2018, 165, A3304−A3312.
(27) Wu, K.; Qian, L.; Sun, X.; Wu, N.; Zhao, H.; Zhang, Y. Influence
of Manganese Ions Dissolved from LiMn2O4 Cathode on the
Degradation of Li4Ti5O12-Based Lithium-Ion Batteries. J. Solid State
Electrochem. 2018, 22, 479−485.
(28) Chen, H.; Xu, H.; Zeng, Y.; Ma, T.; Wang, W.; Liu, L.; Wang, F.;
Zhang, X.; Qiu, X. Quantification on GrowingMass of Solid Electrolyte
Interphase and Deposited Mn(II) on the Silicon Anode of LiMn2O4
Full Lithium-Ion Cells. ACS Appl. Mater. Interfaces 2019, 11, 27839.
(29) Jung, R.; Linsenmann, F.; Thomas, R.; Wandt, J.; Solchenbach,
S.; Maglia, F.; Stinner, C.; Tromp, M.; Gasteiger, H. A. Nickel,
Manganese, and Cobalt Dissolution from Ni-Rich NMC and Their
Effects on NMC622-Graphite Cells. J. Electrochem. Soc. 2019, 166,
A378−A389.

(30) Wang, K.; Xing, L.; Xu, K.; Zhou, H.; Li, W. Understanding and
Suppressing the Destructive Cobalt(II) Species in Graphite Interphase.
ACS Appl. Mater. Interfaces 2019, 11, 31490−31498.
(31) Nagayama, K.; Kamioka, K.; Iwata, E.; Oka, H.; Tokunaga, Y.;
Okada, T. The Reaction of Lithium-Manganese Oxides for the Cathode
Materials of Rechargeable Lithium Batteries with Nonaqueous
Electrolyte. Electrochemistry 2001, 69, 6−9.
(32) Martha, S. K.; Markevich, E.; Burgel, V.; Salitra, G.; Zinigrad, E.;
Markovsky, B.; Sclar, H.; Pramovich, Z.; Heik, O.; Aurbach, D.; et al. A
Short Review on Surface Chemical Aspects of Li Batteries: A Key for a
Good Performance. J. Power Sources 2009, 189, 288−296.
(33) Lee, Y. K.; Park, J.; Lu, W. A Comprehensive Experimental and
Modeling Study on Dissolution in Li-Ion Batteries. J. Electrochem. Soc.
2019, 166, A1340−A1354.
(34) Jang, D. H.; Oh, S. M. Electrolyte Effects on Spinel Dissolution
andCathodic Capacity Losses in 4 V Li / LixMn2O4 Rechargeable Cells.
J. Electrochem. Soc. 1997, 144, 3342−3348.
(35) Abraham, D. P.; Spila, T.; Furczon, M. M.; Sammann, E.
Evidence of Transition-Metal Accumulation on Aged Graphite Anodes
by SIMS. Electrochem. Solid-State Lett. 2008, 11, A226.
(36) Evertz, M.; Horsthemke, F.; Kasnatscheew, J.; Börner, M.;
Winter, M.; Nowak, S. Unraveling Transition Metal Dissolution of
Li1.04Ni1/3Co1/3Mn1/3O2 (NCM111) in Lithium Ion Full Cells by
Using the Total Reflection X-Ray Fluorescence Technique. J. Power
Sources 2016, 329, 364−371.
(37) Zhu, J.; Cao, G.; Li, Y.; Wang, S.; Deng, S.; Guo, J.; Chen, Y.; Lei,
T.; Zhang, J.; Chang, S. Nd2O3 Encapsulation-Assisted Surface
Passivation of Ni-Rich LiNi0.8Co0.1Mn0.1O2 Active Material and
Its Electrochemical Performance. Electrochim. Acta 2019, 325,
No. 134889.
(38) Ruff, Z.; Xu, C.; Grey, C. P. Transition Metal Dissolution and
Degradation in NMC811-Graphite Electrochemical Cells. J. Electro-
chem. Soc. 2021, 168, No. 060518.
(39) Björklund, E.; Xu, C.; Dose, W. M.; Sole, C. G.; Thakur, P. K.;
Lee, T.-L.; De Volder, M. F. L.; Grey, C. P.; Weatherup, R. S. Cycle-
Induced Interfacial Degradation and Transition-Metal Cross-Over in
LiNi0.8Mn0.1Co0.1O2−Graphite Cells. Chem. Mater. 2022, 34, 2034.
(40) Gallus, D. R.; Schmitz, R.; Wagner, R.; Hoffmann, B.; Nowak, S.;
Cekic-Laskovic, I.; Schmitz, R. W.; Winter, M. The Influence of
Different Conducting Salts on the Metal Dissolution and Capacity
Fading of NCM Cathode Material. Electrochim. Acta 2014, 134, 393−
398.
(41) Cha, J.; Han, J.-G.; Hwang, J.; Cho, J.; Choi, N.-S. Mechanisms
for Electrochemical Performance Enhancement by the Salt-Type
Electrolyte Additive, Lithium Difluoro(Oxalato)Borate, in High-
Voltage Lithium-Ion Batteries. J. Power Sources 2017, 357, 97−106.
(42) He, M.; Su, C.-C.; Feng, Z.; Zeng, L.; Wu, T.; Bedzyk, M. J.;
Fenter, P.; Wang, Y.; Zhang, Z. High Voltage LiNi0.5Mn0.3Co0.2O2/
Graphite Cell Cycled at 4.6 V with a FEC/HFDEC-Based Electrolyte.
Adv. Energy Mater. 2017, 7, No. 1700109.
(43) Liao, B.; Hu, X.; Xu, M.; Li, H.; Yu, L.; Fan, W.; Xing, L.; Liao, Y.;
Li, W. Constructing Unique Cathode Interface by Manipulating
Functional Groups of Electrolyte Additive for Graphite/Li-
Ni0.6Co0.2Mn0.2O2 Cells at High Voltage. J. Phys. Chem. Lett. 2018, 9,
3434−3445.
(44) Thompson, L. M.; Stone, W.; Eldesoky, A.; Smith, N. K.;
McFarlane, C. R. M.; Kim, J. S.; Johnson, M. B.; Petibon, R.; Dahn, J. R.
Quantifying Changes to the Electrolyte andNegative Electrode in Aged
NMC532/Graphite Lithium-Ion Cells. J. Electrochem. Soc. 2018, 165,
A2732−A2740.
(45) Zhao, W.; Zheng, B.; Liu, H.; Ren, F.; Zhu, J.; Zheng, G.; Chen,
S.; Liu, R.; Yang, X.; Yang, Y. Toward a Durable Solid Electrolyte Film
on the Electrodes for Li-Ion Batteries with High Performance. Nano
Energy 2019, 63, No. 103815.
(46) Sahore, R.; O’Hanlon, D. C.; Tornheim, A.; Lee, C.-W.; Garcia, J.
C.; Iddir, H.; Balasubramanian,M.; Bloom, I. Revisiting theMechanism
Behind Transition-Metal Dissolution fromDelithiated LiNixMnyCozO2
(NMC) Cathodes. J. Electrochem. Soc. 2020, 167, No. 020513.

The Journal of Physical Chemistry C pubs.acs.org/JPCC Article

https://doi.org/10.1021/acs.jpcc.3c01396
J. Phys. Chem. C 2023, 127, 9509−9521

9518

https://doi.org/10.1149/2.0721514jes
https://doi.org/10.1149/2.0721514jes
https://doi.org/10.1149/2.1111702jes
https://doi.org/10.1149/2.1111702jes
https://doi.org/10.1149/2.1111702jes
https://doi.org/10.1016/S0378-7753(01)00551-1
https://doi.org/10.1016/S0378-7753(01)00551-1
https://doi.org/10.1016/S0378-7753(01)00551-1
https://doi.org/10.1016/S0013-4686(01)00847-7
https://doi.org/10.1016/S0013-4686(01)00847-7
https://doi.org/10.1016/S0013-4686(01)00847-7
https://doi.org/10.1149/1.1502686
https://doi.org/10.1149/1.1502686
https://doi.org/10.1149/1.1759697
https://doi.org/10.1149/1.1759697
https://doi.org/10.1149/2.035308jes
https://doi.org/10.1149/2.035308jes
https://doi.org/10.1149/MA2013-02/14/1057
https://doi.org/10.1149/MA2013-02/14/1057
https://doi.org/10.1149/MA2013-02/14/1057
https://doi.org/10.1149/2.0861412jes
https://doi.org/10.1149/2.0861412jes
https://doi.org/10.1149/2.0861412jes
https://doi.org/10.1039/C4CP00833B
https://doi.org/10.1039/C4CP00833B
https://doi.org/10.1016/j.jpowsour.2015.03.039
https://doi.org/10.1016/j.jpowsour.2015.03.039
https://doi.org/10.1021/acsami.6b02061?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acsami.6b02061?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acsami.6b02061?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1016/j.electacta.2017.09.052
https://doi.org/10.1016/j.electacta.2017.09.052
https://doi.org/10.1149/2.1851712jes
https://doi.org/10.1149/2.1851712jes
https://doi.org/10.1149/2.0511814jes
https://doi.org/10.1149/2.0511814jes
https://doi.org/10.1007/s10008-017-3773-2
https://doi.org/10.1007/s10008-017-3773-2
https://doi.org/10.1007/s10008-017-3773-2
https://doi.org/10.1021/acsami.9b07400?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acsami.9b07400?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acsami.9b07400?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1149/2.1151902jes
https://doi.org/10.1149/2.1151902jes
https://doi.org/10.1149/2.1151902jes
https://doi.org/10.1021/acsami.9b08949?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acsami.9b08949?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.5796/electrochemistry.69.6
https://doi.org/10.5796/electrochemistry.69.6
https://doi.org/10.5796/electrochemistry.69.6
https://doi.org/10.1016/j.jpowsour.2008.09.084
https://doi.org/10.1016/j.jpowsour.2008.09.084
https://doi.org/10.1016/j.jpowsour.2008.09.084
https://doi.org/10.1149/2.0111908jes
https://doi.org/10.1149/2.0111908jes
https://doi.org/10.1149/1.1838016
https://doi.org/10.1149/1.1838016
https://doi.org/10.1149/1.2987680
https://doi.org/10.1149/1.2987680
https://doi.org/10.1016/j.jpowsour.2016.08.099
https://doi.org/10.1016/j.jpowsour.2016.08.099
https://doi.org/10.1016/j.jpowsour.2016.08.099
https://doi.org/10.1016/j.electacta.2019.134889
https://doi.org/10.1016/j.electacta.2019.134889
https://doi.org/10.1016/j.electacta.2019.134889
https://doi.org/10.1149/1945-7111/ac0359
https://doi.org/10.1149/1945-7111/ac0359
https://doi.org/10.1021/acs.chemmater.1c02722?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acs.chemmater.1c02722?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acs.chemmater.1c02722?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1016/j.electacta.2014.04.091
https://doi.org/10.1016/j.electacta.2014.04.091
https://doi.org/10.1016/j.electacta.2014.04.091
https://doi.org/10.1016/j.jpowsour.2017.04.094
https://doi.org/10.1016/j.jpowsour.2017.04.094
https://doi.org/10.1016/j.jpowsour.2017.04.094
https://doi.org/10.1016/j.jpowsour.2017.04.094
https://doi.org/10.1002/aenm.201700109
https://doi.org/10.1002/aenm.201700109
https://doi.org/10.1021/acs.jpclett.8b01099?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acs.jpclett.8b01099?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acs.jpclett.8b01099?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1149/2.0721811jes
https://doi.org/10.1149/2.0721811jes
https://doi.org/10.1016/j.nanoen.2019.06.011
https://doi.org/10.1016/j.nanoen.2019.06.011
https://doi.org/10.1149/1945-7111/ab6826
https://doi.org/10.1149/1945-7111/ab6826
https://doi.org/10.1149/1945-7111/ab6826
pubs.acs.org/JPCC?ref=pdf
https://doi.org/10.1021/acs.jpcc.3c01396?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as


(47) Huang, D.; Engtrakul, C.; Nanayakkara, S.; Mulder, D. W.; Han,
S.-D.; Zhou, M.; Luo, H.; Tenent, R. C. Understanding Degradation at
the Lithium-Ion Battery Cathode/Electrolyte Interface: Connecting
Transition-Metal Dissolution Mechanisms to Electrolyte Composition.
ACS Appl. Mater. Interfaces 2021, 13, 11930−11939.
(48) Su, C.-C.; He, M.; Amine, R.; Chen, Z.; Yu, Z.; Rojas, T.; Cheng,
L.; Ngo, A. T.; Amine, K. Unveiling Decaying Mechanism through
Quantitative Structure-Activity Relationship in Electrolytes for
Lithium-Ion Batteries. Nano Energy 2021, 83, No. 105843.
(49) Dose, W. M.; Temprano, I.; Allen, J. P.; Björklund, E.; O’Keefe,
C. A.; Li, W.; Mehdi, B. L.; Weatherup, R. S.; De Volder, M. F. L.; Grey,
C. P. Electrolyte Reactivity at the Charged Ni-Rich Cathode Interface
and Degradation in Li-Ion Batteries. ACS Appl. Mater. Interfaces 2022,
14, 13206−13222.
(50) Bettge, M.; Li, Y.; Sankaran, B.; Rago, N. D.; Spila, T.; Haasch, R.
T.; Petrov, I.; Abraham, D. P. Improving High-Capacity Li1.2-
Ni0.15Mn0.55Co0.1O2-Based Lithium-Ion Cells by Modifiying the
Positive Electrode with Alumina. J. Power Sources 2013, 233, 346−357.
(51) Li, X.; Liu, J.; Banis,M. N.; Lushington, A.; Li, R.; Cai,M.; Sun, X.
Atomic Layer Deposition of Solid-State Electrolyte Coated Cathode
Materials with Superior High-Voltage Cycling Behavior for Lithium Ion
Battery Application. Energy Environ. Sci. 2014, 7, 768−778.
(52) Xu, G.-L.; Liu, Q.; Lau, K. K. S.; Liu, Y.; Liu, X.; Gao, H.; Zhou,
X.; Zhuang, M.; Ren, Y.; Li, J.; et al. Building Ultraconformal Protective
Layers on Both Secondary and Primary Particles of Layered Lithium
Transition Metal Oxide Cathodes. Nat. Energy 2019, 4, 484−494.
(53)He, Z.; Li, J.; Luo, Z.; Zhou, Z.; Jiang, X.; Zheng, J.; Li, Y.;Mao, J.;
Dai, K.; Yan, C.; Sun, Z. Enhancing Cell Performance of Lithium-Rich
Manganese-Based Materials via Tailoring Crystalline States of a
Coating Layer. ACS Appl. Mater. Interfaces 2021, 13, 49390−49401.
(54) Lee, B.-Y.; Krajewski, M.; Huang, M.-K.; Hasin, P.; Lin, J.-Y.
Spinel LiNi0.5Mn1.5O4 with Ultra-Thin Al2O3 Coating for Li-Ion
Batteries: Investigation of Improved Cycling Performance at Elevated
Temperature. J. Solid State Electrochem. 2021, 25, 2665−2674.
(55) Peng, J.; Li, Y.; Chen, Z.; Liang, G.; Hu, S.; Zhou, T.; Zheng, F.;
Pan, Q.; Wang, H.; Li, Q.; et al. Phase Compatible NiFe2O4 Coating
Tunes Oxygen Redox in Li-Rich Layered Oxide. ACS Nano 2021, 15,
11607−11618.
(56) Wang, J.; Wu, K.; Xu, C.; Hu, X.; Qiu, L. LiNbO3-Coated
Li1.2Mn0.54Ni0.13Co0.13O2 as a Cathode Material with Enhanced
Electrochemical Performances for Lithium-Ion Batteries. J. Mater. Sci.:
Mater. Electron. 2021, 32, 28223−28233.
(57) Xia, Y.; Zhou, Y.; Yoshio, M. Capacity Fading on Cycling of 4 V
Li / LiMn2O4 Cells. J. Electrochem. Soc. 1997, 144, 2593−2600.
(58) Evertz, M.; Lürenbaum, C.; Vortmann, B.; Winter, M.; Nowak, S.
Development of aMethod for Direct Elemental Analysis of Lithium Ion
Battery Degradation Products by Means of Total Reflection X-Ray
Fluorescence. Spectrochim. Acta, Part B 2015, 112, 34−39.
(59) Wandt, J.; Freiberg, A.; Thomas, R.; Gorlin, Y.; Siebel, A.; Jung,
R.; Gasteiger, H. A.; Tromp, M. Transition Metal Dissolution and
Deposition in Li-Ion Batteries Investigated by Operando X-Ray
Absorption Spectroscopy. J. Mater. Chem. A 2016, 4, 18300−18305.
(60) Schwieters, T.; Evertz, M.; Fengler, A.; Börner, M.; Dagger, T.;
Stenzel, Y.; Harte, P.; Winter, M.; Nowak, S. Visualizing Elemental
Deposition Patterns on Carbonaceous Anodes from Lithium Ion
Batteries: A Laser Ablation-Inductively Coupled Plasma-Mass
Spectrometry Study on Factors Influencing the Deposition of Lithium,
Nickel, Manganese and Cobalt after Dissolution and Migration from
the Li1[Ni1/3Mn1/3Co1/3]O2 and LiMn1.5Ni0.5O4 Cathode. J.
Power Sources 2018, 380, 194−201.
(61) Vortmann-Westhoven, B.; Diehl, M.; Winter, M.; Nowak, S. Ion
Chromatography with Post-Column Reaction and Serial Conductivity
and Spectrophotometric Detection Method Development for Quanti-
fication of Transition Metal Dissolution in Lithium Ion Battery
Electrolytes. Chromatographia 2018, 81, 995−1002.
(62) Hanf, L.; Henschel, J.; Diehl, M.; Winter, M.; Nowak, S. Mn2+ or
Mn3+? Investigating Transition Metal Dissolution of Manganese
Species in Lithium Ion Battery Electrolytes by Capillary Electro-
phoresis. Electrophoresis 2020, 41, 697−704.

(63) Zhou, G.; Sun, X.; Li, Q.-H.; Wang, X.; Zhang, J.-N.; Yang, W.;
Yu, X.; Xiao, R.; Li, H. Mn Ion Dissolution Mechanism for Lithium-Ion
Battery with LiMn2O4 Cathode: In Situ Ultraviolet−Visible Spectros-
copy andAb InitioMolecular Dynamics Simulations. J. Phys. Chem. Lett.
2020, 11, 3051−3057.
(64) Tesfamhret, Y.; Younesi, R.; Berg, E. J. Influence of Al2O3
Coatings on HF Induced Transition Metal Dissolution from Lithium-
Ion Cathodes. J. Electrochem. Soc. 2022, 169, No. 010530.
(65) Wang, L.-F.; Ou, C.-C.; Striebel, K. A.; Chen, J.-S. Study of Mn
Dissolution from LiMn2O4 Spinel Electrodes Using Rotating Ring-Disk
Collection Experiments. J. Electrochem. Soc. 2003, 150, A905−A911.
(66) Hawley, W. B.; Parejiya, A.; Bai, Y.; Meyer, H. M.; Wood, D. L.;
Li, J. Lithium and Transition Metal Dissolution Due to Aqueous
Processing in Lithium-Ion Battery Cathode Active Materials. J. Power
Sources 2020, 466, No. 228315.
(67) Huang, J.; Liu, J.; He, J.; Wu, M.; Qi, S.; Wang, H.; Li, F.; Ma, J.
Optimizing Electrode/Electrolyte Interphases and Li-Ion Flux/
Solvation for Lithium-Metal Batteries with Qua-Functional Hepta-
fluorobutyric Anhydride. Angew. Chem., Int. Ed. 2021, 60, 20717−
20722.
(68) Wachs, S. J.; Behling, C.; Ranninger, J.; Möller, J.; Mayrhofer, K.
J. J.; Berkes, B. B. Online Monitoring of Transition-Metal Dissolution
from a High-Ni-Content Cathode Material. ACS Appl. Mater. Interfaces
2021, 13, 33075−33082.
(69) Hanf, L.; Brüning, K.; Winter, M.; Nowak, S. Method
Development for the Investigation of Mn2+/3+, Cu2+, Co2+, and
Ni2+ with Capillary Electrophoresis Hyphenated to Inductively
Coupled Plasma−Mass Spectrometry. Electrophoresis 2023, 44, 89−95.
(70) Klein, S.; Harte, P.; Henschel, J.; Bärmann, P.; Borzutzki, K.;
Beuse, T.; van Wickeren, S.; Heidrich, B.; Kasnatscheew, J.; Nowak, S.;
et al. On the Beneficial Impact of Li2CO3 as Electrolyte Additive in
NCM523 ∥ Graphite Lithium Ion Cells Under High-Voltage
Conditions. Adv. Energy Mater. 2021, 11, No. 2003756.
(71) Klein, S.; van Wickeren, S.; Röser, S.; Bärmann, P.; Borzutzki, K.;
Heidrich, B.; Börner, M.; Winter, M.; Placke, T.; Kasnatscheew, J.
Understanding the Outstanding High-Voltage Performance of
NCM523||Graphite Lithium Ion Cells after Elimination of Ethylene
Carbonate Solvent from Conventional Electrolyte. Adv. Energy Mater.
2021, 11, No. 2003738.
(72) Klein, S.; Harte, P.; van Wickeren, S.; Borzutzki, K.; Röser, S.;
Bärmann, P.; Nowak, S.; Winter, M.; Placke, T.; Kasnatscheew, J. Re-
Evaluating Common Electrolyte Additives for High-Voltage Lithium
Ion Batteries. Cell Rep. Phys. Sci. 2021, 2, No. 100521.
(73) Terada, Y.; Nishiwaki, Y.; Nakai, I.; Nishikawa, F. Study of Mn
Dissolution from LiMn2O4 Spinel Electrodes Using in Situ Total
Reflection X-ray Fluorescence Analysis and Fluorescence XAFS
Technique. J. Power Sources 2001, 97−98, 420−422.
(74) Betz, J.; Brinkmann, J.-P.; Nölle, R.; Lürenbaum, C.; Kolek, M.;
Stan, M. C.; Winter, M.; Placke, T. Cross Talk between Transition
Metal Cathode and Li Metal Anode: Unraveling Its Influence on the
Deposition/Dissolution Behavior and Morphology of Lithium. Adv.
Energy Mater. 2019, 9, No. 1900574.
(75) Evertz,M.; Kasnatscheew, J.;Winter,M.; Nowak, S. Investigation
of Various Layered Lithium Ion Battery Cathode Materials by Plasma-
and X-Ray-Based Element Analytical Techniques. Anal. Bioanal. Chem.
2019, 411, 277−285.
(76) Zhao, L.; Chénard, E.; Çapraz, Ö. Ö.; Sottos, N. R.; White, S. R.
Direct Detection of Manganese Ions in Organic Electrolyte by UV-Vis
Spectroscopy. J. Electrochem. Soc. 2018, 165, A345−A348.
(77) Hanf, L.; Diehl, M.; Kemper, L.-S.; Winter, M.; Nowak, S.
Investigating the Oxidation State of Fe from LiFePO4-Based Lithium
Ion Battery Cathodes via Capillary Electrophoresis. Electrophoresis
2020, 41, 1549−1556.
(78) Hanf, L.; Diehl, M.; Kemper, L.-S.; Winter, M.; Nowak, S.
Accessing Copper Oxidation States of Dissolved Negative Electrode
Current Collectors in Lithium Ion Batteries. Electrophoresis 2020, 41,
1568−1575.

The Journal of Physical Chemistry C pubs.acs.org/JPCC Article

https://doi.org/10.1021/acs.jpcc.3c01396
J. Phys. Chem. C 2023, 127, 9509−9521

9519

https://doi.org/10.1021/acsami.0c22235?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acsami.0c22235?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acsami.0c22235?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1016/j.nanoen.2021.105843
https://doi.org/10.1016/j.nanoen.2021.105843
https://doi.org/10.1016/j.nanoen.2021.105843
https://doi.org/10.1021/acsami.1c22812?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acsami.1c22812?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1016/j.jpowsour.2013.01.082
https://doi.org/10.1016/j.jpowsour.2013.01.082
https://doi.org/10.1016/j.jpowsour.2013.01.082
https://doi.org/10.1039/C3EE42704H
https://doi.org/10.1039/C3EE42704H
https://doi.org/10.1039/C3EE42704H
https://doi.org/10.1038/s41560-019-0387-1
https://doi.org/10.1038/s41560-019-0387-1
https://doi.org/10.1038/s41560-019-0387-1
https://doi.org/10.1021/acsami.1c11180?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acsami.1c11180?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acsami.1c11180?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1007/s10008-021-05047-0
https://doi.org/10.1007/s10008-021-05047-0
https://doi.org/10.1007/s10008-021-05047-0
https://doi.org/10.1021/acsnano.1c02023?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acsnano.1c02023?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1007/s10854-021-07199-1
https://doi.org/10.1007/s10854-021-07199-1
https://doi.org/10.1007/s10854-021-07199-1
https://doi.org/10.1149/1.1837870
https://doi.org/10.1149/1.1837870
https://doi.org/10.1016/j.sab.2015.08.005
https://doi.org/10.1016/j.sab.2015.08.005
https://doi.org/10.1016/j.sab.2015.08.005
https://doi.org/10.1039/C6TA08865A
https://doi.org/10.1039/C6TA08865A
https://doi.org/10.1039/C6TA08865A
https://doi.org/10.1016/j.jpowsour.2018.01.088
https://doi.org/10.1016/j.jpowsour.2018.01.088
https://doi.org/10.1016/j.jpowsour.2018.01.088
https://doi.org/10.1016/j.jpowsour.2018.01.088
https://doi.org/10.1016/j.jpowsour.2018.01.088
https://doi.org/10.1016/j.jpowsour.2018.01.088
https://doi.org/10.1007/s10337-018-3540-2
https://doi.org/10.1007/s10337-018-3540-2
https://doi.org/10.1007/s10337-018-3540-2
https://doi.org/10.1007/s10337-018-3540-2
https://doi.org/10.1007/s10337-018-3540-2
https://doi.org/10.1002/elps.201900443
https://doi.org/10.1002/elps.201900443
https://doi.org/10.1002/elps.201900443
https://doi.org/10.1002/elps.201900443
https://doi.org/10.1021/acs.jpclett.0c00936?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acs.jpclett.0c00936?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acs.jpclett.0c00936?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1149/1945-7111/ac4ab1
https://doi.org/10.1149/1945-7111/ac4ab1
https://doi.org/10.1149/1945-7111/ac4ab1
https://doi.org/10.1149/1.1577543
https://doi.org/10.1149/1.1577543
https://doi.org/10.1149/1.1577543
https://doi.org/10.1016/j.jpowsour.2020.228315
https://doi.org/10.1016/j.jpowsour.2020.228315
https://doi.org/10.1002/anie.202107957
https://doi.org/10.1002/anie.202107957
https://doi.org/10.1002/anie.202107957
https://doi.org/10.1021/acsami.1c07932?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acsami.1c07932?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1002/elps.202200139
https://doi.org/10.1002/elps.202200139
https://doi.org/10.1002/elps.202200139
https://doi.org/10.1002/elps.202200139
https://doi.org/10.1002/aenm.202003756
https://doi.org/10.1002/aenm.202003756
https://doi.org/10.1002/aenm.202003756
https://doi.org/10.1002/aenm.202003738
https://doi.org/10.1002/aenm.202003738
https://doi.org/10.1002/aenm.202003738
https://doi.org/10.1016/j.xcrp.2021.100521
https://doi.org/10.1016/j.xcrp.2021.100521
https://doi.org/10.1016/j.xcrp.2021.100521
https://doi.org/10.1016/S0378-7753(01)00741-8
https://doi.org/10.1016/S0378-7753(01)00741-8
https://doi.org/10.1016/S0378-7753(01)00741-8
https://doi.org/10.1016/S0378-7753(01)00741-8
https://doi.org/10.1002/aenm.201900574
https://doi.org/10.1002/aenm.201900574
https://doi.org/10.1002/aenm.201900574
https://doi.org/10.1007/s00216-018-1441-8
https://doi.org/10.1007/s00216-018-1441-8
https://doi.org/10.1007/s00216-018-1441-8
https://doi.org/10.1149/2.1111802jes
https://doi.org/10.1149/2.1111802jes
https://doi.org/10.1002/elps.202000097
https://doi.org/10.1002/elps.202000097
https://doi.org/10.1002/elps.202000155
https://doi.org/10.1002/elps.202000155
pubs.acs.org/JPCC?ref=pdf
https://doi.org/10.1021/acs.jpcc.3c01396?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as


(79) Jang, D. H.; Shin, Y. J.; Oh, S. M. Dissolution of Spinel Oxides
and Capacity Losses in 4 V Li / LixMn2O4 Cells. J. Electrochem. Soc.
1996, 143, 2204−2211.
(80) Grey, C. P.; Dupré, N. NMR Studies of Cathode Materials for
Lithium-Ion Rechargeable Batteries. Chem. Rev. 2004, 104, 4493−
4512.
(81) Kerlau, M.; Reimer, J. A.; Cairns, E. J. Investigation of Particle
Isolation in Li-Ion Battery Electrodes Using 7Li NMR Spectroscopy.
Electrochem. Commun. 2005, 7, 1249−1251.
(82) Key, B.; Bhattacharyya, R.; Morcrette, M.; Seznéc, V.; Tarascon,
J.-M.; Grey, C. P. Real-TimeNMR Investigations of Structural Changes
in Silicon Electrodes for Lithium-Ion Batteries. J. Am. Chem. Soc. 2009,
131, 9239−9249.
(83) Salager, E.; Sarou-Kanian, V.; Sathiya, M.; Tang, M.; Leriche, J.-
B.; Melin, P.; Wang, Z.; Vezin, H.; Bessada, C.; Deschamps, M.;
Tarascon, J. M. Solid-State NMR of the Family of Positive Electrode
Materials Li2Ru1−YSnyO3 for Lithium-Ion Batteries.Chem. Mater. 2014,
26, 7009−7019.
(84) Pecher, O.; Carretero-González, J.; Griffith, K. J.; Grey, C. P.
Materials’ Methods: NMR in Battery Research. Chem. Mater. 2017, 29,
213−242.
(85) Krachkovskiy, S. A.; Foster, J. M.; Bazak, J. D.; Balcom, B. J.;
Goward, G. R. Operando Mapping of Li Concentration Profiles and
Phase Transformations in Graphite Electrodes by Magnetic Resonance
Imaging and Nuclear Magnetic Resonance Spectroscopy. J. Phys. Chem.
C 2018, 122, 21784−21791.
(86) Märker, K.; Xu, C.; Grey, C. P. Operando NMR of NMC811/
Graphite Lithium-Ion Batteries: Structure, Dynamics, and Lithium
Metal Deposition. J. Am. Chem. Soc. 2020, 142, 17447−17456.
(87) Meyer, B. M.; Leifer, N.; Sakamoto, S.; Greenbaum, S. G.; Grey,
C. P. High Field Multinuclear NMR Investigation of the SEI Layer in
Lithium Rechargeable Batteries. Electrochem. Solid-State Lett. 2005, 8,
A145.
(88) Dupre, N.; Cuisinier, M.; Guyomard, D. Electrode/Electrolyte
Interface Studies in Lithium Batteries Using NMR. Interface Mag. 2011,
20, 61−67.
(89) Leifer, N.; Smart, M. C.; Prakash, G. K. S.; Gonzalez, L.; Sanchez,
L.; Smith, K. A.; Bhalla, P.; Grey, C. P.; Greenbaum, S. G. 13C Solid
State NMR Suggests Unusual Breakdown Products in SEI Formation
on Lithium Ion Electrodes. J. Electrochem. Soc. 2011, 158, A471−A480.
(90) Cuisinier, M.; Martin, J.-F.; Moreau, P.; Epicier, T.; Kanno, R.;
Guyomard, D.; Dupré, N. Quantitative MAS NMR Characterization of
the LiMn1/2Ni1/2O2 Electrode/Electrolyte Interphase. Solid State Nucl.
Magn. Reson. 2012, 42, 51−61.
(91) Huff, L. A.; Tavassol, H.; Esbenshade, J. L.; Xing, W.; Chiang, Y.-
M.; Gewirth, A. A. Identification of Li-Ion Battery SEI Compounds
through 7Li and 13C Solid-State MAS NMR Spectroscopy andMALDI-
TOF Mass Spectrometry. ACS Appl. Mater. Interfaces 2016, 8, 371−
380.
(92) Michan, A. L.; Leskes, M.; Grey, C. P. Voltage Dependent Solid
Electrolyte Interphase Formation in Silicon Electrodes: Monitoring the
Formation of Organic Decomposition Products. Chem. Mater. 2016,
28, 385−398.
(93) Haber, S.; Leskes,M.What CanWe Learn from Solid State NMR
on the Electrode−Electrolyte Interface? Adv. Mater. 2018, 30,
No. 1706496.
(94) Jin, Y.; Kneusels, N.-J. H.; Marbella, L. E.; Castillo-Martínez, E.;
Magusin, P. C. M. M.; Weatherup, R. S.; Jónsson, E.; Liu, T.; Paul, S.;
Grey, C. P. Understanding Fluoroethylene Carbonate and Vinylene
Carbonate Based Electrolytes for Si Anodes in Lithium Ion Batteries
with NMR Spectroscopy. J. Am. Chem. Soc. 2018, 140, 9854−9867.
(95) Campion, C. L.; Li, W.; Lucht, B. L. Thermal Decomposition of
LiPF6-Based Electrolytes for Lithium-Ion Batteries. J. Electrochem. Soc.
2005, 152, A2327−A2334.
(96) Plakhotnyk, A. V.; Ernst, L.; Schmutzler, R. Hydrolysis in the
System LiPF6�Propylene Carbonate�Dimethyl Carbonate�H2O. J.
Fluorine Chem. 2005, 126, 27−31.
(97) Wilken, S.; Treskow, M.; Scheers, J.; Johansson, P.; Jacobsson, P.
Initial Stages of Thermal Decomposition of LiPF6-Based Lithium Ion

Battery Electrolytes by Detailed Raman and NMR Spectroscopy. RSC
Adv. 2013, 3, 16359−16364.
(98) Wiemers-Meyer, S.; Winter, M.; Nowak, S. Mechanistic Insights
into Lithium Ion Battery Electrolyte Degradation − a Quantitative
NMR Study. Phys. Chem. Chem. Phys. 2016, 18, 26595−26601.
(99) Ota, H.; Sakata, Y.; Inoue, A.; Yamaguchi, S. Analysis of Vinylene
Carbonate Derived SEI Layers on Graphite Anode. J. Electrochem. Soc.
2004, 151, A1659−A1669.
(100) Xu, K.; Zhuang, G. V.; Allen, J. L.; Lee, U.; Zhang, S. S.; Ross, P.
N.; Jow, T. R. Syntheses and Characterization of Lithium Alkyl Mono-
and Dicarbonates as Components of Surface Films in Li-Ion Batteries. J.
Phys. Chem. B 2006, 110, 7708−7719.
(101) Nie, M.; Chalasani, D.; Abraham, D. P.; Chen, Y.; Bose, A.;
Lucht, B. L. Lithium Ion Battery Graphite Solid Electrolyte Interphase
Revealed by Microscopy and Spectroscopy. J. Phys. Chem. C 2013, 117,
1257−1267.
(102) Zhao, J.; Wang, L.; He, X.; Wan, C.; Jiang, C. Determination of
Lithium-Ion Transference Numbers in LiPF6−PC Solutions Based on
Electrochemical Polarization and NMR Measurements. J. Electrochem.
Soc. 2008, 155, A292.
(103) Hayamizu, K. Temperature Dependence of Self-Diffusion
Coefficients of Ions and Solvents in Ethylene Carbonate, Propylene
Carbonate, and Diethyl Carbonate Single Solutions and Ethylene
Carbonate + Diethyl Carbonate Binary Solutions of LiPF6 Studied by
NMR. J. Chem. Eng. Data 2012, 57, 2012−2017.
(104) Richardson, P. M.; Voice, A. M.; Ward, I. M. Pulsed-Field
Gradient NMR Self Diffusion and Ionic Conductivity Measurements
for Liquid Electrolytes Containing LiBF4 and Propylene Carbonate.
Electrochim. Acta 2014, 130, 606−618.
(105) Krachkovskiy, S. A.; Bazak, J. D.; Werhun, P.; Balcom, B. J.;
Halalay, I. C.; Goward, G. R. Visualization of Steady-State Ionic
Concentration Profiles Formed in Electrolytes during Li-Ion Battery
Operation and Determination of Mass-Transport Properties by in Situ
Magnetic Resonance Imaging. J. Am. Chem. Soc. 2016, 138, 7992−
7999.
(106) Feng, Z.; Higa, K.; Han, K. S.; Srinivasan, V. Evaluating
Transport Properties and Ionic Dissociation of LiPF6 in Concentrated
Electrolyte. J. Electrochem. Soc. 2017, 164, A2434.
(107) Krachkovskiy, S. A.; Bazak, J. D.; Fraser, S.; Halalay, I. C.;
Goward, G. R. Determination of Mass Transfer Parameters and Ionic
Association of LiPF6: Organic Carbonates Solutions. J. Electrochem. Soc.
2017, 164, A912−A916.
(108)Oldiges, K.; Diddens, D.; Ebrahiminia, M.; Hooper, J. B.; Cekic-
Laskovic, I.; Heuer, A.; Bedrov, D.; Winter, M.; Brunklaus, G.
Understanding Transport Mechanisms in Ionic Liquid/Carbonate
Solvent Electrolyte Blends. Phys. Chem. Chem. Phys. 2018, 20, 16579−
16591.
(109) Peng, J.; Gobet, M.; Devany, M.; Xu, K.; Cresce, A. v. W.;
Borodin, O.; Greenbaum, S. Multinuclear Magnetic Resonance
Investigation of Cation-Anion and Anion-Solvent Interactions in
Carbonate Electrolytes. J. Power Sources 2018, 399, 215−222.
(110) Bazak, J. D.; Allen, J. P.; Krachkovskiy, S. A.; Goward, G. R.
Mapping of Lithium-Ion Battery Electrolyte Transport Properties and
Limiting Currents with In Situ MRI. J. Electrochem. Soc. 2020, 167,
No. 140518.
(111) Yang, L.; Xiao, A.; Lucht, B. L. Investigation of Solvation in
Lithium Ion Battery Electrolytes by NMR Spectroscopy. J. Mol. Liq.
2010, 154, 131−133.
(112) Bogle, X.; Vazquez, R.; Greenbaum, S.; Cresce, A. v. W.; Xu, K.
Understanding Li+−Solvent Interaction in Nonaqueous Carbonate
Electrolytes with 17O NMR. J. Phys. Chem. Lett. 2013, 4, 1664−1668.
(113) Seo, D. M.; Reininger, S.; Kutcher, M.; Redmond, K.; Euler, W.
B.; Lucht, B. L. Role of Mixed Solvation and Ion Pairing in the Solution
Structure of Lithium Ion Battery Electrolytes. J. Phys. Chem. C 2015,
119, 14038−14046.
(114) Peng, J.; Carbone, L.; Gobet, M.; Hassoun, J.; Devany, M.;
Greenbaum, S. Natural Abundance Oxygen-17 NMR Investigation of
Lithium Ion Solvation in Glyme-Based Electrolytes. Electrochim. Acta
2016, 213, 606−612.

The Journal of Physical Chemistry C pubs.acs.org/JPCC Article

https://doi.org/10.1021/acs.jpcc.3c01396
J. Phys. Chem. C 2023, 127, 9509−9521

9520

https://doi.org/10.1149/1.1836981
https://doi.org/10.1149/1.1836981
https://doi.org/10.1021/cr020734p?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/cr020734p?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1016/j.elecom.2005.09.003
https://doi.org/10.1016/j.elecom.2005.09.003
https://doi.org/10.1021/ja8086278?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/ja8086278?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/cm503280s?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/cm503280s?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acs.chemmater.6b03183?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acs.jpcc.8b06563?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acs.jpcc.8b06563?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acs.jpcc.8b06563?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/jacs.0c06727?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/jacs.0c06727?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/jacs.0c06727?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1149/1.1854117
https://doi.org/10.1149/1.1854117
https://doi.org/10.1149/2.F06113if
https://doi.org/10.1149/2.F06113if
https://doi.org/10.1149/1.3559551
https://doi.org/10.1149/1.3559551
https://doi.org/10.1149/1.3559551
https://doi.org/10.1016/j.ssnmr.2011.09.001
https://doi.org/10.1016/j.ssnmr.2011.09.001
https://doi.org/10.1021/acsami.5b08902?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acsami.5b08902?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acsami.5b08902?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acs.chemmater.5b04408?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acs.chemmater.5b04408?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acs.chemmater.5b04408?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1002/adma.201706496
https://doi.org/10.1002/adma.201706496
https://doi.org/10.1021/jacs.8b03408?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/jacs.8b03408?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/jacs.8b03408?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1149/1.2083267
https://doi.org/10.1149/1.2083267
https://doi.org/10.1016/j.jfluchem.2004.09.027
https://doi.org/10.1016/j.jfluchem.2004.09.027
https://doi.org/10.1039/C3RA42611D
https://doi.org/10.1039/C3RA42611D
https://doi.org/10.1039/C6CP05276B
https://doi.org/10.1039/C6CP05276B
https://doi.org/10.1039/C6CP05276B
https://doi.org/10.1149/1.1785795
https://doi.org/10.1149/1.1785795
https://doi.org/10.1021/jp0601522?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/jp0601522?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/jp3118055?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/jp3118055?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1149/1.2837832
https://doi.org/10.1149/1.2837832
https://doi.org/10.1149/1.2837832
https://doi.org/10.1021/je3003089?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/je3003089?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/je3003089?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/je3003089?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/je3003089?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1016/j.electacta.2014.03.072
https://doi.org/10.1016/j.electacta.2014.03.072
https://doi.org/10.1016/j.electacta.2014.03.072
https://doi.org/10.1021/jacs.6b04226?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/jacs.6b04226?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/jacs.6b04226?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/jacs.6b04226?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1149/2.0941712jes
https://doi.org/10.1149/2.0941712jes
https://doi.org/10.1149/2.0941712jes
https://doi.org/10.1149/2.1531704jes
https://doi.org/10.1149/2.1531704jes
https://doi.org/10.1039/C8CP01485J
https://doi.org/10.1039/C8CP01485J
https://doi.org/10.1016/j.jpowsour.2018.07.095
https://doi.org/10.1016/j.jpowsour.2018.07.095
https://doi.org/10.1016/j.jpowsour.2018.07.095
https://doi.org/10.1149/1945-7111/abc0c9
https://doi.org/10.1149/1945-7111/abc0c9
https://doi.org/10.1016/j.molliq.2010.04.025
https://doi.org/10.1016/j.molliq.2010.04.025
https://doi.org/10.1021/jz400661k?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/jz400661k?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acs.jpcc.5b03694?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1021/acs.jpcc.5b03694?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as
https://doi.org/10.1016/j.electacta.2016.07.144
https://doi.org/10.1016/j.electacta.2016.07.144
pubs.acs.org/JPCC?ref=pdf
https://doi.org/10.1021/acs.jpcc.3c01396?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as


(115) Chapman, N.; Borodin, O.; Yoon, T.; Nguyen, C. C.; Lucht, B.
L. Spectroscopic and Density Functional Theory Characterization of
Common Lithium Salt Solvates in Carbonate Electrolytes for Lithium
Batteries. J. Phys. Chem. C 2017, 121, 2135−2148.
(116) Su, C.-C.; He, M.; Amine, R.; Chen, Z.; Amine, K. Internally
Referenced DOSY-NMR: A Novel Analytical Method in Revealing the
Solution Structure of Lithium-Ion Battery Electrolytes. J. Phys. Chem.
Lett. 2018, 9, 3714−3719.
(117) Blanc, F.; Leskes, M.; Grey, C. P. In Situ Solid-State NMR
Spectroscopy of Electrochemical Cells: Batteries, Supercapacitors, and
Fuel Cells. Acc. Chem. Res. 2013, 46, 1952−1963.
(118) Arai, J.; Okada, Y.; Sugiyama, T.; Izuka, M.; Gotoh, K.; Takeda,
K. In Situ Solid State 7Li NMR Observations of Lithium Metal
Deposition during Overcharge in Lithium Ion Batteries. J. Electrochem.
Soc. 2015, 162, A952−A958.
(119) Freytag, A. I.; Pauric, A. D.; Krachkovskiy, S. A.; Goward, G. R.
In Situ Magic-Angle Spinning 7Li NMR Analysis of a Full Electro-
chemical Lithium-Ion Battery Using a Jelly Roll Cell Design. J. Am.
Chem. Soc. 2019, 141, 13758−13761.
(120) Pell, A. J.; Pintacuda, G.; Grey, C. P. Paramagnetic NMR in
Solution and the Solid State. Prog. Nucl. Magn. Reson. Spectrosc. 2019,
111, 1−271.
(121) Bertini, I.; Luchinat, C.; Parigi, G.; Ravera, E. NMR of
Paramagnetic Molecules: Applications to Metallobiomolecules and Models;
Elsevier, 2016.
(122) Solomon, I. Relaxation Processes in a System of Two Spins.
Phys. Rev. 1955, 99, 559−565.
(123) Bloembergen, N. Proton Relaxation Times in Paramagnetic
Solutions. J. Chem. Phys. 1957, 27, 572−573.
(124) Bloembergen, N.; Purcell, E.M.; Pound, R. V. Relaxation Effects
in Nuclear Magnetic Resonance Absorption. Phys. Rev. 1948, 73, 679−
712.
(125) Bodart, P. R.; Rachocki, A.; Tritt-Goc, J.; Michalke, B.; Schmitt-
Kopplin, P.; Karbowiak, T.; Gougeon, R. D. Quantification of
Manganous Ions in Wine by NMR Relaxometry. Talanta 2020, 209,
No. 120561.
(126) Bray, J. M.; Davenport, A. J.; Ryder, K. S.; Britton, M. M.
Quantitative, In Situ Visualization of Metal-Ion Dissolution and
Transport Using 1H Magnetic Resonance Imaging. Angew. Chem., Int.
Ed. 2016, 55, 9394−9397.
(127) Allen, J. P.; Grey, C. P. Determining the Oxidation States of
Dissolved Transition Metals in Battery Electrolytes from Solution
NMR Spectra. Chem. Commun. 2023, 59, 1677−1680.
(128) Allen, J. P.; Grey, C. P. Solution NMR of Battery Electrolytes:
Assessing and Mitigating Spectral Broadening Caused by Transition
Metal Dissolution. J. Phys. Chem. C 2023, 127, No. 4425.
(129) Carr, H. Y.; Purcell, E. M. Effects of Diffusion on Free
Precession in Nuclear Magnetic Resonance Experiments. Phys. Rev.
1954, 94, 630−638.
(130) Meiboom, S.; Gill, D. Modified Spin-Echo Method for
Measuring Nuclear Relaxation Times. Rev. Sci. Instrum. 1958, 29,
688−691.
(131) Bloembergen, N.; Morgan, L. O. Proton Relaxation Times in
Paramagnetic Solutions. Effects of Electron Spin Relaxation. J. Chem.
Phys. 1961, 34, 842−850.
(132) Swift, T. J.; Connick, R. E. NMR-RelaxationMechanisms of O17

in Aqueous Solutions of Paramagnetic Cations and the Lifetime of
Water Molecules in the First Coordination Sphere. J. Chem. Phys. 1962,
37, 307−320.
(133) Wang, C.; Xing, L.; Vatamanu, J.; Chen, Z.; Lan, G.; Li, W.; Xu,
K. Overlooked Electrolyte Destabilization by Manganese (II) in
Lithium-Ion Batteries. Nat. Commun. 2019, 10, No. 3423.
(134) Blint, R. J. Binding of Ether and Carbonyl Oxygens to Lithium
Ion. J. Electrochem. Soc. 1995, 142, 696−702.
(135) Yanase, S.; Oi, T. Solvation of Lithium Ion in Organic
Electrolyte Solutions and Its Isotopie Reduced Partition Function
Ratios Studied by Ab Initio Molecular Orbital Method. J. Nucl. Sci.
Technol. 2002, 39, 1060−1064.

(136)Wang, Y.; Balbuena, P. B. Theoretical Studies on Cosolvation of
Li Ion and Solvent Reductive Decomposition in Binary Mixtures of
Aliphatic Carbonates. Int. J. Quantum Chem. 2005, 102, 724−733.
(137) Bhatt, M. D.; Cho, M.; Cho, K. Interaction of Li+ Ions with
Ethylene Carbonate (EC): Density Functional Theory Calculations.
Appl. Surf. Sci. 2010, 257, 1463−1468.
(138) Ong, M. T.; Verners, O.; Draeger, E. W.; van Duin, A. C. T.;
Lordi, V.; Pask, J. E. Lithium Ion Solvation and Diffusion in Bulk
Organic Electrolytes from First-Principles and Classical Reactive
Molecular Dynamics. J. Phys. Chem. B 2015, 119, 1535−1545.
(139) Shakourian-Fard, M.; Kamath, G.; Sankaranarayanan, S. K. R. S.
Evaluating the Free Energies of Solvation and Electronic Structures of
Lithium-Ion Battery Electrolytes. ChemPhysChem 2016, 17, 2916−
2930.
(140) Johnson, N. M.; Zhang, Z. NMR-Guided High-Temperature
Electrolyte Design Using a Novel PF5 Marker. J. Phys. Chem. C 2020,
124, 13602−13608.
(141) Kosen, P. A. Spin Labeling of Proteins.Methods in Enzymology;
Nuclear Magnetic Resonance Part B Structure and Mechanism; Academic
Press, 1989; Vol. 177, pp 86−121.
(142) Gottstein, D.; Reckel, S.; Dötsch, V.; Güntert, P. Requirements
on Paramagnetic Relaxation Enhancement Data for Membrane Protein
Structure Determination by NMR. Structure 2012, 20, 1019−1027.
(143) Göbl, C.; Madl, T.; Simon, B.; Sattler, M. NMR Approaches for
Structural Analysis of Multidomain Proteins and Complexes in
Solution. Prog. Nucl. Magn. Reson. Spectrosc. 2014, 80, 26−63.
(144) Du Pasquier, A.; Blyr, A.; Courjal, P.; Larcher, D.; Amatucci, G.;
Gérand, B.; Tarascon, J.-M. Mechanism for Limited 55 °C Storage
Performance of Li1.05Mn1.95O4 Electrodes. J. Electrochem. Soc. 1999,
146,