A nanorod-like Ni-rich layered cathode with enhanced Li+diffusion pathways for high-performance lithium-ion batteries

Article abstract of DOI:10.1039/d0ta10608a

Ni-rich LiNi_xCo_yMn_1?x?yO₂(x≥ 0.6) layered oxide cathodes are among the most promising cathode materials for lithium-ion batteries (LIBs) owing to their superior capacity, prominent energy density and low cost. However, the large volume change caused by phase transition and poor diffusion kinetics limits their application. Herein, a nanorod-like Ni-rich layered LiNi_0.6Co_0.2Mn_0.2O₂cathode is synthesizedviaa facile surfactant-free co-precipitation route. Due to the unique nanorod morphology, more {010} electrochemically active planes are exposed. As a result, structural stability and diffusion kinetics are greatly improved. In terms of performance, it exhibits outstanding structural stability (the volume change is as small as 2.12% in the processes of charging and discharging) and rate performance (achieving a high discharge capacity of 152.2 mA h g^?1at 5C). Such rationally designed cathode could meet the high high-energy requirements of next generation LIBs.

Full text of DOI:10.1039/d0ta10608a

View Article Online
View Journal
Journal of
Materials Chemistry A
Materials for energy and sustainability
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: F. Li, Z. Liu, J.
Shen, X. Xu, L. Zeng, B. Zhang, H. Zhu, Q. Liu, J. Liu and M. Zhu, J. Mater. Chem. A, 2021, DOI:
1
0.1039/D0TA10608A.
Volume
Number 12
March 2018
Pages 4883-5230
6
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
28
Journal of
Materials Chemistry A
Materials for energy and sustainability
rsc.li/materials-a
Accepted Manuscripts are published online shortly after acceptance,
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
shall the Royal Society of Chemistry be held responsible for any errors
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
ISSN 2050-7488
COMMUNICATION
Zhenhai Wen et al.
An electrochemically neutralized energy-assisted low-cost
acid-alkaline electrolyzer for energy-saving electrolysis
hydrogen generation
rsc.li/materials-a

Page 1 of 30
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/D0TA10608A
+
Nanorod-like Ni-rich layered cathode with enhanced Li diffusion pathway for
high-performance lithium-ion batteries
a
a
a
a
a
b
Fangkun Li , Zhengbo Liu , Jiadong Shen , Xijun Xu , Liyan Zeng , Binghao Zhang ,
b
b, *
a, *
a
He Zhu , Qi Liu , Jun Liu , Min Zhu
aGuangdong Provincial Key Laboratory of Advanced Energy Storage Materials, School
of Materials Science and Engineering, South China University of Technology,
Guangzhou 510641, P. R. China, E-mail: msjliu@scut.edu.cn
bDepartment of Physics, City University of Hong Kong, Hong Kong 999077, P. R.
China, E-mail: qiliu63@cityu.edu.hk
Abstract
Ni-rich LiNi Co Mn
O (x 0.6) layered oxide cathodes are one of the most
x
y
1xy
2
promising cathode materials for lithium-ion batteries (LIBs) owing to their superior
capacity, prominent energy density and low cost. However, the large volume change
caused by phase transition and poor diffusion kinetics limits its application. Herein, a
nanorod-like Ni-rich layered LiNi Co Mn O cathode is synthesized via a facial
0
.6
0.2
0.2
2
surfactant-free co-precipitation route. Due to the unique nanorod morphology, more
010} electrochemical active planes are exposed. As a result, structural stability and
{
diffusion kinetics are improved a lot. In terms of performance, it exhibits outstanding
structural stability (the volume change is as small as 2.12% in the processes of charging
and discharging) and rate performance (achieve a high discharge capacity of 152.2 mAh
g at 5 C). Such rational designed cathode could meet the high high-energy
1

Journal of Materials Chemistry A
Page 2 of 30
View Article Online
DOI: 10.1039/D0TA10608A
requirements of the next generation LIBs.
Keywords: Li-ion batteries, Ni-rich layered cathode, diffusion kinetics, volume change
1
Introduction
Pursuing the efficient use of environmentally friendly and low carbon emission clean
energy has been stimulating a wide range of research interests on lithium-ion batteries
LIBs).1 At present, electric vehicles (EVs) are widely used in our life causing a daily-
5
(
increasing demand for high energy density LIBs.6 It is well known that the cathode is
an indispensable component, which considerably determines the whole energy density
of batteries. To meet market demands, the development of high-capacity cathode
8
materials is an irresistible trend. In this regard, Ni-rich LiNi Co Mn
O (x0.6)
x
y
1xy
2
layered cathodes have been attracting significant attention because of their superior
capacity, environment temperately and low cost.9
11
Unfortunately, these layered
oxides suffer from intrinsic low rate capability, severe capacity fade, and rapid voltage
+
12
decay leading to sluggish Li ion transport dynamics. To overcome these issues, a
wide range of strategies have been proposed and investigated to enhance the chemical
and structural stabilities by surface engineering,13, 14 element doping,1518 and
morphology control.1
925
2
6
2729
To date, one-dimensional (1D) nanostructures, including nanorods, nanowires,
nanotube arrays30, 31 and nanobelts, etc., have been widely investigated to improve the
electrochemical performances of electrode materials. Particularly, the unique
morphology of 1D electrode can offer short electron/ion transport distance and strong
32

Page 3 of 30
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/D0TA10608A
tolerance to stress change, thus deliver high capacity, superior rate performance and
+
long-term cycling. Generally, the relationship between the Li diffusion coefficient (
) and the transportation length (L) abides the Eq. (1):33
퐷퐿푖
+
퐿2

= 퐷
(1)
+
퐿푖
Where  is diffusion time in electrode materials. The nanosized primary particles in 1D
+
nanomaterials can shorten the transmission length (L) of Li , thus decrease the diffusion
+
time (), resulting in enhanced Li diffusion kinetics of LIBs, remarkably improving
the rate performance. Certainly, many previous research results revealed that the
nanosized materials with enhanced electrochemical dynamics could efficiently improve
the rate performance. For example, Winter et al. proved that a major part of the overall
3
4
specific capacity loss was induced by kinetic limitations, and Passerini et al. verified
that it was beneficial to enhance the rate performance by synthesis 1D nanomaterials.
+
Its unique structure could offer fast Li ion transport pathways, thus significantly
enhancing the lithium-ions diffusion kinetics.35
Over and above that special structure design, another clever strategy to resolve the
+
sluggish Li transportation is that expose more electrochemical active planes (i. e., {010}
planes).3
638
In principle, Ni-rich NCM cathode possesses a typical hexagonal -
+
NaFeO type structure with R 3m space group providing 2D channels for Li diffusion
2
along either a- or b-axis. The densely packed MO (M=Ni, Co, Mn) octahedral
6
perpendicular to the c-axis form the MO layers (i. e., {001} facets) that are inactive
2
+
39
electrochemical facets impeding the Li transporting. By contrast, the six equivalent
side planes of (100), (100), (010), (010), (110) and (110) denoted by {010} planes,

Journal of Materials Chemistry A
Page 4 of 30
View Article Online
DOI: 10.1039/D0TA10608A
which are considered as the favorable electrochemical active planes offering an open
+
23
structure for Li diffusion. Nevertheless, it is still a huge challenge that fabricates
layered structure cathode with more exposed {010} active planes, because the surface
4
0
free energy of {010} planes is higher than that of the {001} ones. An effective strategy
was that adding a surfactant to slowing down the crystal growth rate of {001} facets
and thus achieving the Ni-rich cathode with more exposed {010} active planes.
Recently, many surfactants have been adopted to control the morphology of Ni-rich
cathode with more exposed electrochemical active planes, such as polyethylene glycol
PEG),26, 32 polyvinylpyrrolidone (PVP), and sodium dodecyl sulfate (SDS),
41
36, 42
and
(
so on. However, the addition of organic surfactants (PEG, PVP, and SDS, etc.)
undoubtedly increases the synthetic cost and thus hampering its practical applications.
Although, LiNi Co Mn O , LiNi Co Mn O , Li Ni Mn O
and
NaLi0.05Ni Mn Cu Mg0.05O2 with exposed {010} active planes have been
0
.8
0.1
0.1
2
1/3
1/3
1/3
2
1.2
0.2
0.6
2
0.3
0.5
0.1
successfully synthesized and greatly studied. To the best of our knowledge, synthesis
of nano-like LiNi Co Mn O with exposed {010} active facets via a surfactant-free
0
.6
0.2
0.2
2
route has never been published.
Herein, a nanorod-like Ni-rich layered cathode of LiNi Co Mn O with
0
.6
0.2
0.2
2
prominent exposed {010} electrochemical active facets has been synthesized via a
facial surfactant-free oxalate precursor crystallization route combined with a solid
lithiation treatment. The in-situ synchrotron high-energy X-ray diffraction (HEXRD)
technique exhibits that the Ni-rich LiNi Co Mn O has a stable lattice structure and
0
.6
0.2
0.2
2
strong tolerance to stress changes during the charge/discharge process (the unit cell

Page 5 of 30
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/D0TA10608A
volume change is as small as 2.12%). Moreover, the synergistic effect between
exposure {010} electrochemical active surface and nanometer size dramatically shorten
the Li+ diffusion pathways and thus enhance diffusion kinetics improving the rate
performance.
2
Experimental section
Material Synthesis
Preparation of the MC O xH O precursor
2
4
2
In a typical process, 12 mmol of Ni(CH COO) 4H O, 4 mmol
3
2
2
Co(CH COO) 4H O 4 mmol Mn(CH COO) 4H O and 23 mmol of LiCH COO2H O
3
2
2
3
2
2
3
2
were dissolved in 200 ml binary solvent system with ethanol-water (ethanol: water=
:1 v/v) under continuous stirring to form transparent solution A. On the other hand, 40
mmol H C O 2H O) was poured into another 200 ml mixture solution (the same as the
4
2
2
4
2
above solution) under vigorous stirring to obtain colorless clear solution B. Then, the
solution B was injected into A with stirring for another 6 h. After that, the MC O xH O
2
4
2
(M= Li, Ni, Co, Mn) nanorods were collected by evaporating the solvents and drying
the as-prepared pink precipitate in an air-dry oven at 80 ℃ for 18 h.
Preparation of the nanorod-like LiNi Co Mn O cathode
0
.6
0.2
0.2
2
The as-obtained MC O xH O nanorods precursor was pre-treated in a muffle furnace
2
4
2
at 450 ℃ for 8 h and then temperature raised to 800 ℃ for 15 h to obtain the layered
nanorod-like LiNi Co Mn O cathode (marked as N-NCM).
0
.6
0.2
0.2
2

Journal of Materials Chemistry A
Page 6 of 30
View Article Online
DOI: 10.1039/D0TA10608A
Materials Characterization
The crystal information of as-prepared powder was performed on a PANalytical
Empyrean X-ray diffraction (XRD) at 40 kV with a measurement current of 45 mA and
equipped with a Cu-K radiation source. The measured data of XRD were in-depth
analyzed by the Rietveld refinement program-General Structure Analysis System
(GSAS) software. Fourier Transform Infrared Spectroscopy (FT-IR) spectra were

1
collected using an FT-IR Nicolet IS50 instrument for 4000 to 400 cm . The as-prepared
products were mixed with KBr powder for FT-IR measurements. Background
correction was made using a blank KBr pellet as the reference. TG was characterized

1
by Q50 thermogravimetric analyzer from 40 to 800 ℃ at 10 ℃ min in O atmosphere.
2
Morphology of as-prepared N-NCM was revealed by a Scanning Electron Microscope
(
SEM, Zeiss Gemini DSM 982). The microstructures and elemental distribution of as-
prepared products were observed by a JEOL 2100F Transmission Electron Microscope
TEM) at 200 kV. The valence states of Ni, Co and Mn in N-NCM cathode were
(
performed by X-ray photoelectron spectroscopy (XPS) with ThermoFisher ESCALAB
XI+ system (Al kα radiation, 1486.6 eV). To compare the thermal stability of N-NCM
and commercial LiNi Co Mn O (C-NCM) cathodes, DSC was recorded from 40
0
.6
0.2
0.2
2
to 350 ℃ using a TA-Q20 Differential Scanning Calorimetry with a heating rate of 5 ℃

1
+
min . For the DSC tests, the cathode materials were charged to 4.4 V vs Li/Li at C/10
rate and then disassembled and washed with diethyl carbonate (DEC) solvent three
times in an Ar-filled glove box. After that, scratching the powders from the dried
electrodes package into high-pressure crucibles with electrolyte. In-situ synchrotron

Page 7 of 30
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/D0TA10608A
XRD measurements were carried out at 11-ID-C beamline with the X-ray wavelength
of 0.1173 Å at Advanced Photon Source (APS), Argonne National Laboratory (ANL),
and Si (113) single crystal was employed as the monochromator of an X-ray beam at
1
05.7 keV. The coin cells have a hole in the middle, which is convenient for the X-ray
directly irradiating the N-NCM electrode. During the test process, the charge-discharge
current density of the cell was C/10 rate, and the data collection time for a single XRD
pattern was within 8 s. The original two-dimensional diffraction data was collected by
a Perkin-Elmer detector, and they were integrated and calibrated via Fit2D software.
All the XRD patterns were refined and corresponding lattice parameters were extracted
using Fullprof software.43 In detail, the backgrounds were removed by linear
interpolation and the peak shapes were demonstrated through the Thompson-Cox-
Hastings profile function when using the Lebail method.
Electrochemical Measurements
For working electrodes, N-NCM (or C-NCM), polyvinylidene fluoride (PVDF)
and Super P with a weight ratio of 8: 1: 1 were mixed in a mortar with N-methyl-2-
pyrrolidinone (NMP) to get a homogeneous slurry and then spread on a clean Al foil
and dried in a vacuum oven at 100 ℃ for overnight. Then, the electrode was cut into

2
1
2-mm disks with the active mass loading around 2.3± 0.2 mg cm . The test CR2025
coin-type cells were assembled in an Ar-filled glove box with both H O and O < 0.01
2
2
ppm. 1M LiPF dissolved in EC: DMC: EMC (1: 1: 1 in volume) used as the electrolyte,
6
Li foil as counter-electrode and polypropylene as separators. Galvanostatic testing of

Journal of Materials Chemistry A
Page 8 of 30
View Article Online
DOI: 10.1039/D0TA10608A
+
the cells was charged/discharged between 2.8 and 4.4～4.6 V (vs Li/ Li ) at 30 and 60 ℃
using a Land 2001A testing system. CV and EIS curves were collected on an
electrochemical workstation (Gamry Interface 1000). CV curves were tests at 0.1 mV

1
s in a voltage range of 2.84.4 V. EIS profiles were recorded with an amplitude of 5
5
2
mV from10 Hz to 10 . The GITT was performed with a constant current pulse for 10
min at C/10 rate and then rest for 1 h.
3
Results and Discussion
Fig. 1a demonstrates the preparation steps of nanorod-like LiNi Co Mn O (N-
0
.6
0.2
0.2
2
NCM), including a co-precipitation step in the ethanol-water system and followed by a
solid lithiation treatment. Firstly, the uniform hydrated metal oxalates MC O xH O
2
4
2
(M= Li, Ni, Co, Mn) precursor was acquired via a simple surfactant-free co-
precipitation method. Subsequently, the as-synthesized MC O xH O precursor
2
4
2
directly annealing in a furnace under air condition to obtain the N-NCM nanorod. The
SEM signal of the precursor (Fig. 1b) reveals that the MC O xH O possesses a
2
4
2
nanorod-like morphology with a width of ~400 nm and a length of ~3 m. The XRD
pattern (Fig. S1) and FT-IR spectrum (Fig. S2) prove that the as-obtained precursor is
4
4
composed of Li C O and (Ni, Co, Mn)C O 2H O To well-inherit the morphology
2
2
4
2
4
2
of precursor and rational design the lithiation procedure, the TG/DTG result of
MC O xH O was also measured (Fig. S3). The SEM results of the final product (Fig.
2
4
2
1
c) suggest that the N-NCM final product well-preserved the shape of MC O xH O
2
4
2
nanorods. Also, the morphology characterization of commercial LiNi Co Mn O
2
0
.6
0.2
0.2

Page 9 of 30
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/D0TA10608A
(
marked as C-NCM) cathode was performed and compared with the designed N-NCM.
The SEM image (Fig. S4) shows the C-NCM particles with an average size of ~2 m
and corresponding SEM-EDS mapping signals (Fig. S5) reveal that all the elements are
uniformly distributed. Fig. S6 displays the N adsorption/desorption isotherms of N-
2
NCM and C-NCM cathode and the surface area of N-NCM can be calculated as 3.315
2
1
2
1
m g which is higher than that of C-NCM (1.014 m g ).
The structural characterization of N-NCM and C-NCM were collected by the
powder X-ray diffraction (XRD) pattern and depicted in Fig. 1d and Fig. S6b, which
are well matched with hexagonal -NaFeO structure (space group, R 3m) without
2
impurity phase. The crystallographic and atomic site information of N-NCM and C-
NCM received from the Rietveld refinements are listed in Table S1-4. Compared to C-
NCM, the N-NCM exhibits smaller lattice parameters a and c indicating that the N-
1
8
NCM cathode has a better crystallinity. The intensity ratios (I(003)/I(104)) of N-NCM
+
2+
and C-NCM are both larger than 1.2, which demonstrates the slight degree of Li / Ni
mixed cationic.45, 46 Furthermore, the splits of (006)/(102) and (018)/(110) reveal that
the Ni-rich layered oxides possess a highly ordered structure. The intensity ratio value
of I(110)/ I(018) of the N-NCM is 1.07 from the XRD patterns (Fig.1d) which are higher
than that of C-NCM (0.96, Fig. S7c). A bigger value of I(110)/ I(018) indicates that N-
NCM has {010} oriented active facets caused by the faster growth of these high-energy
facets.3
6, 4750
As shown in Fig. S8, the (110) planes have an open layered interspace for
+
+
the Li transporting. But for (108) planes, there are no straight tunnels for Li diffusion
owing to the dense stacking of atoms. To verify the morphology characteristics and the

Journal of Materials Chemistry A
Page 10 of 30
View Article Online
DOI: 10.1039/D0TA10608A
Fig. 1. (a) Schematic illustration for the preparation of nanorod-like
LiNi Co Mn O (N-NCM) cathode; (b, c) SEM images of the nanorod-like
0
.6
0.2
0.2
2
MC O xH O (M= Ni, Co, Mn, Li) precursor and N-NCM cathode; (d) refined XRD
2
4
2
patterns of N-NCM cathode based on LiNiO hexagonal (R 3m) phases and enlarged
2
view of (108) and (110) peaks; (e-g) TEM, HRTEM images, and SAED pattern of the
N-NCM cathode; (h) crystal structure of N-NCM cathode; (i) elemental EDS mapping
of Ni, Co, Mn, and all elements.
lattice structure of N-NCM, the high-resolution transmission electron microscope
(HRTEM) and selected area electron diffraction (SAED) measurements were

Page 11 of 30
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/D0TA10608A
performed. The TEM image of N-NMC (Fig. 1e) displays a nanorod-like shape, which
is consistent with the SEM results (Fig.1d). The HRTEM image (Fig. 1f) exhibits clear
lattice fringes with an interplanar spacing of 4.72 Å, which can be assigned to the (003)
planes. Combined with the corresponding SAED patterns (Fig. 1g), it is confirmed that
these N-NCM nanorods with a hexagonal layered structure. Furthermore, the lattice
fringes of region 1 in Fig. 1f displays an interplanar distance of 2.80 Å, which can be
indexed to the (100) planes. This demonstrates that the lateral plane was classified to
the {010} electrochemical active facets (parallel to the c-axis direction), which can
+
offer more unobstructed pathways for fast Li insertion and extraction. In addition, the
easily recognizable crystalline structure schematic of N-NCM is illustrated in Fig. 1h.
As displayed in Fig. S9, the nanorod-like N-NCM cathode with preferred orientation
{
010} facets is also verified by SAED patterns characterization. To check the elemental
composition of N-NCM, TEM-EDS elemental mapping was also collected. Fig. 1i
exhibits the EDS mappings signals of Ni, Co, Mn, and O elements reveal that all these
elements are evenly distributed. In summary, the 1D N-NCM nanorods were
successfully obtained by controlling the growth of {010} planes via a rational design
of the synthesis procedure. The X-ray photoelectron spectroscopy (XPS)
characterization was performed to investigate the valence state of Ni, Co, and Mn
elements. Fig. S10 displays the wide scan spectrum of N-NCM confirming the co-exist
of C, O, Mn, Co and Ni elements. As exhibited in Fig. S10b-d, the characteristic peaks
2
+
3+
3+
centred at 853.5/854.7, 780.1 and 641.9 eV could be assigned to the Ni /Ni , Co and
4
+
25, 51, 52
Mn , respectively.

Journal of Materials Chemistry A
Page 12 of 30
View Article Online
DOI: 10.1039/D0TA10608A
Fig. 2. Electrochemical performances of the N-NCM cathode: (a) the charge-discharge

1
profiles of the first cycle at C/2 (1 C= 180 mAh g ) rate between 2.8 and 4.44.6 V at
3
0 ℃; (b) differential capacity profiles of the first charge-discharge cycle; (c) long-term
cycling performances at C/2 rate between 2.8 and 4.44.6 V; (d) cycling performances
at C/3 rate in the voltage range of 2.84.4 V at 30 and 60 ℃.
As displayed in Fig. 2 and Fig. S11., the cycling performances of N-NCM
electrodes are measured under 2.84.4 V, 2.84.5 V and 2.84.6 V at a C/2 rate (1 C=

1
1
80 mA g ) in 30 ℃ conditions. The initial charge-discharge profiles of N-NCM (Fig.
2
a) at different potential region indicates that with the cut-off voltage increases, the
capacity increases. Furthermore, at a high cut-off voltage of 4.6 V, this N-NCM cathode
possesses a high initial Coulombic efficiency of 84.5% and a high-capacity retention

Page 13 of 30
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/D0TA10608A
rate of 82.1% after 100 cycles. To further unveil the charge/discharge mechanism, the

1
relevant differential capacitance (dQ·dV ) curves of N-NCM as a function of the cell
voltage was provided in Fig. 2b. These profiles are typically characterized by two
couples of redox peaks (even at 4.6 V cut-off voltage) and small redox reaction potential
difference. This phenomenon is associated with the structural transition of N-NCM with
a biphasic region from hexagonal to monoclinic (H1 to M) and a monoclinic to
+
53-55
hexagonal (M to H2) during the Li extraction/insertion.
On account the working
temperature plays a vital role in the battery health and life, the N-NCM electrode was
also tested at both 30 and 60 ℃ (Fig. 2d and Fig. S12). Evidently, the N-NCM cathode
possesses capacity retention of 95.4% and 79.7% after 100 cycles in the voltage region
of 2.84.4 V at 30 ℃ and 60 ℃, respectively.
To evaluate the advantages of this nanorod cathode, the electrochemical performance
comparison of N-NCM and C-NCM was also performed. Fig. 3a,b show the results of
cyclic voltammetry (CV) characterization, in which the initial oxidation/reduction
2
+
4+
peaks (Ni /Ni redox processes) of N-NCM and C-NCM are situated at 3.898/3.653
V and 3.924/3.629 V, respectively. Moreover, it can be checked that the peak separation
of the N-NCM cathode at a lower 0.245 V in the first cycle indicates a smaller
polarization degree of the N-NCM cathode.46 These results suggest that the Li+
(
de)intercalation in the N-NCM cathode is easier. The rate capabilities of these two
samples were further studied at from C/10 to 5 C in a potential range of 2.84.4 V (Fig.
c). It is evident that the N-NCM achieves a higher capacity and batter rate capability
than C-NCM in all the tests. Even at a 5 C rate, the N-NCM electrode still delivers a
3

Journal of Materials Chemistry A
Page 14 of 30
View Article Online
DOI: 10.1039/D0TA10608A
+
Fig. 3. The Li storage properties of the N-NCM (red line) and C-NCM (black line)
-1
cathodes in the range of 2.84.4 V at 30 ℃: (a,b) the CV profiles at 0.1 mV s for initial
two cycles; (c) rate capability at different charge-discharge rates (C/10, C/5, C/2, 1 C,
2
C, and 5 C) (Dis.: discharge, CE: Coulombic efficiency); (d) average midpoint
potential at different charge-discharge rates; (e) cycling stability at 5 C.

1
discharge capacity of ~138 mAh g , which is much higher than that of C-NCM (~120

1
mAh g ). Besides, N-NCM displays better cycling stability and higher capacity than
C-NCM when it returns to the C/10 rate. Fig. 3d shows the average midpoint potentials

Page 15 of 30
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/D0TA10608A
at each C-rates of N-NCM and C-NCM. Obviously, when the current density increases
to 5 C, the voltage drop of N-NCM (0.17 V) is much lower than that of C-NCM (0.26
V). Fig. S13 shows the corresponding charge-discharge curves and differential
discharge capacity curves suggest that N-NCM better electrochemical performance and
has smaller polarization.
Based on the above results, the cycling stability is also tested at 5 C in the voltage
range of 2.84.4 V and offered in Fig. 3e and Fig. S14ac. Obviously, N-NCM has a

1
discharge capacity of 152.2 mAh g , which is higher than that of C-NCM (143.0 mAh

1
g ). It’s noted that the N-NCM still has a high reversible capacity of 90.6% after 200
cycles but for C-NCM only 85.0% after 100 cycles. To investigate the intrinsic
characteristics of N-NCM undergoes during the cycling process, the corresponding
st
th
th
th
differential capacity versus voltage (dQ/dV) curves of the 1 , 50 , 100 , 150 , and
th
2
00 cycles at 5 C was conducted. As shown in Fig. S14d, it is evident verified that no
new phase transition appears in the long-term cycles even at high current rates of 5 C.
Simultaneously, the XRD pattern validates that the N-NCM cathode still possesses a
complete hexagonal layered structure (R3m, space group) (Fig. S15a). The EIS results
th
after 200 cycles (Fig. S15b) with a larger value than the initial one indicates the
+
deteriorating of Li diffusion kinetics and also explains the small capacity decay during
the cycling process.34, 56, 57. Notably, the N-NCM cathode also achieved excellent cycle
stability at 2 C for 100 cycles (Fig. S16). Compared to the electrochemical performance
with other reported LiNi Co Mn O -based materials (Table S5), the N-NCM
0
.6
0.2
0.2
2
nanorods cathode exhibit a better high-rate capability and more stable long cycle life.

Journal of Materials Chemistry A
Page 16 of 30
View Article Online
DOI: 10.1039/D0TA10608A
Fig. 4. (a) In-situ synchrotron XRD patterns of the first charge and discharge of N-
NCM cathode between 2.8 and 4.4 V at a C/10 rate. Cell potentials are given at the left
of the figure; (b) enlarged view of (003) and (113) peaks; (c) lattice constants evolution
and unit cell volume change of N-NCM cathode as a function of time during the first
cycle.

Page 17 of 30
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/D0TA10608A
These test results indicate that the more exposed {010} active planes enhanced the
diffusion kinetic by reducing the transport distance, thus improving the rate
performance and cycling stability.
In-situ synchrotron XRD was further performed to understand the superior high-
rate capability and long-term cycling performance of the N-NCM cathode. The
obtained XRD patterns of N-NCM were fitted to reveal the evolution of phases and
change of lattice parameters. The refined initial in-situ XRD result was provided in Fig.
S17 and the corresponding lattice parameters extracted from each XRD pattern were
listed in Table S6. As lithium ions are removed from the layered structure, the a-axis
lattice parameter decreases while the c-axis lattice parameter initially expands.
According to the counterplot of XRD patterns, there is a phase change from the
beginning hexagonal phase H1 to a novel hexagonal phase H2 and a coexistence of H1
and H2 during the charging process (Fig. 4b). It is worth noting that there is no
formation of the H3 phase during charging, which avoids the more dramatic phase
transition. The stacked XRD patterns and change of c-axis both provide the evidence
to support this point (Fig. 4c). During discharging, there is no split of peaks suggesting
that no phase change exists in this process. At the same time, the volumetric change is
as small as 2.12%, much lower than previously reported.58, 59 In addition, the ex-situ
XRD patterns were also performed to reveal volume changes of N-NCM and C-NCM
cathode. Apparently, the as-fabricated N-NCM product has smaller volume changes
than that of C-NCM (Fig. S18 and S19, Table S6 and S7). This suggests that the
nanorod-like N-NCM significantly relieves phase transition and volumetric change

Journal of Materials Chemistry A
Page 18 of 30
View Article Online
DOI: 10.1039/D0TA10608A
+
during Li insertion/extraction, thus suppressing the capacity fade.
Galvanostatic intermittent titration technique (GITT) surveys were conducted to
+
evaluate the Li diffusion coefficient (퐷 ) and the results provided in Fig. 5a,b. The
퐿푖 +
can be calculated using the GITT diffusion equation (Fick’s second law):60
퐷퐿푖
+
2
2
퐿2
4
휋휏(
푛푀푉푀
푆
∆푉푠
퐷퐿푖
+
=
(휏 ≤ 퐷
(2)
)
(∆푉푡
)
)
+
퐿푖
+
2
1
where 퐷퐿푖
+
is the Li diffusivity (cm s ), τ is the time duration of the pulse (s), S is
2
3
the cell interfacial area (cm ), n and V are the molar mass (mol) and volume (cm
M
M

1
mol ) of the active material, respectively. ΔV is the potential difference at the state of
s
+
equilibrium (V), ΔV is the polarization potential (V), and L is the length of Li diffusion
t
(cm). The single titration step of the GITT curve plus vs. cell voltage is provided in Fig.
S20a,b, in which the different parameters of V , IR , V , V , V , etc. are schematically
o
drop
1
2
3
1
/2
presented. The E and  show a good linear relationship in Fig. S20c,d which indicates
that 퐷퐿푖 can be estimated based on the GITT diffusion equation. The 퐷퐿푖 speedily
increase at the beginning of charging (SOC < 20%) along with the expansion of the c
+
+
+
24, 61
parameter, thus broadening the Li diffusion path.
It’s obvious that the 퐷퐿푖
+
of N-
NCM electrode is two orders of magnitude higher than that of the C-NCM electrode
+
during the Li desertion (charge) process (Fig. 5a,b). Moreover, the 퐷
퐿푖 +
of N-NCM

8
2 1
electrode is 4.6  10 cm s at the state of 60% charge, while that of C-NCM is only
1
.2  10 cm s . Furthermore, the N-NCM electrode is more stable than that of the
C-NCM electrode during discharge processes. The thermal stabilities of the delithiated
after charging to 4.4 V at C/10) N-NCM and C-NCM electrodes were both performed
by DSC and displayed close thermal stability (Fig. S21).
10
2 1
(

Page 19 of 30
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/D0TA10608A
+
Fig. 5. (a,b) The GITT curves (red line) and Li diffusion coefficients (blue line) of the
N-NCM (a) and C-NCM (b) cathodes in the voltage of 2.84.4 V at C/10 rate. (c-e) the
Nyquist plots of N-NCM and C-NCM cathodes in the fresh half-cell (c) and after 100th
cycles (e) over 2.84.4 V at 2 C rate, and (d) shows the relation between Z' and the
square root of frequency (1/2) derived from a low-frequency region of corresponding
th
EIS; (f) the equivalent circuits of fresh half-cell (①) and after 100 cycles (②) were
used to fit the experimental data, R : solution resistance; R : surface film resistance; and
s
f
R : charge transfer resistance; CPE: constant phase element; W : Warburg element
ct
o
(open).

Journal of Materials Chemistry A
Page 20 of 30
View Article Online
DOI: 10.1039/D0TA10608A
To further realize the difference between N-NCM and C-NCM electrodes,
electrochemical impedance spectrum (EIS) tests were also performed to investigate the
+
Li diffusion coefficient. The EIS of N-NCM and C-NCM electrodes before cycling
th
(
Fig. 5c) and after 100 cycles (Fig. 5e) in 2.84.4 V at 2 C rate were measured and the
typical Nyquist plots were further stimulated to form the equivalent circuit by Z-view
software (Fig. 5f). The specific parameters are shown in Table 1. Specially,퐷퐿푖 in the
+
electrode materials is related to the straight line in the low frequency (Warburg
diffusion region) abiding the following equation (3):62
푅2푇2
퐷퐿푖
+
= 2 2 4 4 2 2
(3)
(4)
(5)
퐴 푛 퐹 퐶 휎
3
C=
푁퐴 × 푉
-1/2
Z'= R + R + 
D
L
Where R is the ideal gas constant, T is the absolute temperature, F is the Faraday
constant, n is the number of oxidized electrons per molecule, A is the surface area of
+
the electrode, and C is the concentration of Li in the cathode, which can be calculated
from formula (4) (LiNi Co Mn O has a similar -NaFeO type layered structure
0
.6
0.2
0.2
2
2
to LiCoO with three Li-ions in a unit cell). N is the Avogadro constant and V is the
2
A
cell volume.  is the Warburg coefficient, related to Z' in formula (5), which is the slope
in the relationship between the Z' and the square root of frequency (1/2) (Fig. 5d).
Before cycling, the R values are about 61.3 and 79.1  for N-NCM and C-NCM,
ct
respectively. Discernibly, the N-NCM cathode exhibits a smaller impedance and a

9
2
1
11
2 1
higher 퐷퐿푖
+
of 1.6210 cm s than that of C-NCM (5.5710 cm s ), indicating
an enhanced electron and ion transport. Also, the N-NCM electrode exhibits smaller Rf

Page 21 of 30
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/D0TA10608A
and R values than that of the C-NCM electrode after 100 cycles. In conclusion, the
ct
smaller impedance and higher 퐷퐿푖 of N-NCM are attributed to nanorod-like
+
morphology with exposed {010} active planes offering more unobstructed channels for
Li-ions diffusion. In addition, the nano-sized rod shape of the N-NCM cathode
+
dramatically reduces the Li diffusion distance endowing a fast transport rate. As a
result, the N-NCM cathode exhibits excellent rate performance and cycling stability.
Furthermore, the detailed SEM (Fig. 6a) and TEM (Fig. 6b,c) images also confirm that
the current N-NCM cathode maintained 1D nanorod structure after 200 cycles.
Perfectly, there is no crack in these particles indicates outstanding structural stability
during repeated cycles. Interestingly, Fig. 6d shows a nanorod with a typical crystalline
orientation. It can be observed from the HRTEM image (Fig. 6e) and its corresponding
SAED pattern (Fig. 6f) that the c-axis is alone in the radial direction of the N-NCM
nanorod. It can be inferred that the lateral faces of the nanorod are the active {010}
facets and these active {010} facets occupied a high proportion.
Table 1. Simulated results of the Nyquist plots.
Fresh
Cycle 100th
Sample
푫푳풊
+
[cm2
R [Ω] R [Ω] W - [Ω]
R [Ω] R [Ω] R [Ω]
s
ct
o R
s
f
ct

1
s ]
1.6210
9
N-NCM
C-NCM
4.3
5.9
61.3
79.1
1.7
32.3
5.4
7.5
78.5
443.5
766.2
5.5710
11
126.2

Journal of Materials Chemistry A
Page 22 of 30
View Article Online
DOI: 10.1039/D0TA10608A
Fig. 6. Morphology and microstructure of the N-NCM cathode after cycling: (a) SEM
image, (b-e) TEM and HRTEM images and (f) SAED pattern of the N-NCM cathode
after 100 cycles at 2 C rate and 30 ℃.
4
Conclusions
A nanorod-like LiNi Co Mn O cathode has been successfully synthesized via a
0
.6
0.2
0.2
2
facial surfactant-free synthesis route. Such unique morphology makes more {010}
+
electrochemical active plane exposed, further shorten the diffusion distance of Li ions.
Systematic investigations show that its diffusion kinetic is improved due to this
microstructure design, as a result, it displays excellent rate performance and structural
stability. In the process of cycling, this cathode could suppress the H2-H3 phase
transition with an ultra-low strain of 2.12% in volume. In addition, when the rate is

Page 23 of 30
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/D0TA10608A

1
raised to 5 C, this cathode still exhibits a high capacity of 152.2 mAh g with capacity
retention of 90.6% even after 200 cycles. The superior electrochemical performance N-
NCM cathode achieved lay a solid foundation for the practical application of Ni-rich
materials. Meanwhile, the simple synthesis route without organic surfactants provides
an avenue to obtain nanomaterials with exposed electrochemical active planes applying
on the filed of secondary batteries supercapacitors and catalysis.
Acknowledgments
This research was accomplished with the support from the National Natural Science
Foundation of China (no. 51771076), Innovative Research Groups of the National
Natural Science Foundation of China (no. NSFC51621001), and Guangdong “Pearl
River Talents Plan” (no. 2017GC010218).
References
1
2
.
.
M. Armand and J. M. Tarascon, Nature, 2008, 451, 652657.
L. Zhang, X. Qin, S. Zhao, A. Wang, J. Luo, Z. L. Wang, F. Kang, Z. Lin and B.
Li, Adv. Mater., 2020, 32, 1908445.
3
.
S. Zhao, C. D. Sewell, R. Liu, S. Jia, Z. Wang, Y. He, K. Yuan, H. Jin, S. Wang,
X. Liu and Z. Lin, Adv. Energy Mater., 2020, 10, 1902657.
B. Jiang, C. Han, B. Li, Y. He and Z. Lin, ACS Nano, 2016, 10, 27282735.
B. Jiang, Y. He, B. Li, S. Zhao, S. Wang, Y. B. He and Z. Lin, Angew. Chem., Int.
Ed., 2017, 56, 18691872.
4
5
.
.

Journal of Materials Chemistry A
Page 24 of 30
View Article Online
DOI: 10.1039/D0TA10608A
6
.
V. Etacheri, R. Marom, R. Elazari, G. Salitra and D. Aurbach, Energy Environ.
Sci., 2011, 4, 32433262.
7
.
.
A. Konarov, S.-T. Myung and Y.-K. Sun, ACS Energy Lett., 2017, 2, 703708.
H. Zhu, Y. Huang, H. Zhu, L. Wang, S. Lan, X. Xia and Q. Liu, Small Methods,
8
2
020, 4, 1900223.
9
1
1
1
.
F. Lin, I. M. Markus, D. Nordlund, T.-C. Weng, M. D. Asta, H. L. Xin and M. M.
Doeff, Nat. Commun., 2014, 5, 3529.
0. W. Liu, P. Oh, X. Liu, M.-J. Lee, W. Cho, S. Chae, Y. Kim and J. Cho, Angew.
Chem., Int. Ed., 2015, 54, 44404457.
1. J. Kim, H. Lee, H. Cha, M. Yoon, M. Park and J. Cho, Adv. Energy Mater., 2018,
8
, 1702028.
2. Y. Wei, J. Zheng, S. Cui, X. Song, Y. Su, W. Deng, Z. Wu, X. Wang, W. Wang,
M. Rao, Y. Lin, C. Wang, K. Amine and F. Pan, J. Am. Chem. Soc., 2015, 137,
8
3648367.
3. H. Kim, M. G. Kim, H. Y. Jeong, H. Nam and J. Cho, Nano Lett., 2015, 15,
1112119.
4. L. Yao, F. Liang, J. Jin, B. V. R. Chowdari, J. Yang and Z. Wen, Chem. Eng. J.,
020, 389, 124403.
1
1
1
2
2
5. F. Schipper, H. Bouzaglo, M. Dixit, E. M. Erickson, T. Weigel, M. Talianker, J.
Grinblat, L. Burstein, M. Schmidt, J. Lampert, C. Erk, B. Markovsky, D. T. Major
and D. Aurbach, Adv. Energy Mater., 2018, 8, 1701682.
1
6. D. Kong, J. Hu, Z. Chen, K. Song, C. Li, M. Weng, M. Li, R. Wang, T. Liu, J. Liu,

Page 25 of 30
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/D0TA10608A
M. Zhang, Y. Xiao and F. Pan, Adv. Energy Mater., 2019, 9, 1901756.
1
1
1
2
2
7. T. Weigel, F. Schipper, E. M. Erickson, F. A. Susai, B. Markovsky and D. Aurbach,
ACS Energy Lett., 2019, 4, 508516.
8. C. Zhang, J. Wan, Y. Li, S. Zheng, K. Zhou, D. Wang, D. Wang, C. Hong, Z. Gong
and Y. Yang, J. Mater. Chem. A, 2020, 8, 68936901.
9. Y.-K. Sun, S.-T. Myung, M.-H. Kim, J. Prakash and K. Amine, J. Am. Chem. Soc.,
2
005, 127, 1341113418.
0. Y.-K. Sun, Z. Chen, H.-J. Noh, D.-J. Lee, H.-G. Jung, Y. Ren, S. Wang, C. S. Yoon,
S.-T. Myung and K. Amine, Nat. Mater., 2012, 11, 942947.
1. P. Yan, J. Zheng, J. Liu, B. Wang, X. Cheng, Y. Zhang, X. Sun, C. Wang and J.-
G. Zhang, Nat. Energy., 2018, 3, 600605.
2
2
2. X. Zeng, C. Zhan, J. Lu and K. Amine, Chem, 2018, 4, 690704.
3. X. Xu, H. Huo, J. Jian, L. Wang, H. Zhu, S. Xu, X. He, G. Yin, C. Du and X. Sun,
Adv. Energy Mater., 2019, 9, 1803963.
2
2
2
4. L.-P. He, K. Li, Y. Zhang and J. Liu, ACS Appl. Mater. Interfaces, 2020, 12,
2
825328263.
5. Z. Zheng, X.-D. Guo, S.-L. Chou, W.-B. Hua, H.-K. Liu, S. X. Dou and X.-S.
Yang, Electrochim. Acta, 2016, 191, 401410.
6. H. Liu, G. Liang, C. Gao, S. Bi, Q. Chen, Y. Xie, S. Fan, L. Cao, W. K. Pang and
Z. Guo, Nano Energy, 2019, 66, 104100.
2
2
7. Y. Lee, M. G. Kim and J. Cho, Nano Lett., 2008, 8, 957961.
8. J. Liu, K. Song, C. Zhu, C.-C. Chen, P. A. van Aken, J. Maier and Y. Yu, ACS

Journal of Materials Chemistry A
Page 26 of 30
View Article Online
DOI: 10.1039/D0TA10608A
Nano, 2014, 8, 70517059.
2
3
3
3
9. K. Yu, X. Pan, G. Zhang, X. Liao, X. Zhou, M. Yan, L. Xu and L. Mai, Adv.
Energy Mater., 2018, 8, 1802369.
0. X. Xu, J. Liu, Z. Liu, Z. Wang, R. Hu, J. Liu, L. Ouyang and M. Zhu, Small, 2018,
1
4, 1800793.
1. J. Liu, X. Xu, J. Shen, F. Li, Z. Wang, D. Zhang and S. Zuo, Chem- Eur J, 2020,
6,14708−14714.
2. J. Lu, Q. Peng, W. Wang, C. Nan, L. Li and Y. Li, J. Am. Chem. Soc., 2013, 135,
6491652.
2
1
3
3
3. T. Jin, Q. Han, Y. Wang and L. Jiao, Small, 2018, 14, 1703086.
4. J. Kasnatscheew, M. Evertz, B. Streipert, R. Wagner, R. Klöpsch, B. Vortmann,
H. Hahn, S. Nowak, M. Amereller, A. C. Gentschev, P. Lamp and M. Winter,
Phys. Chem. Chem. Phys., 2016, 18, 39563965.
3
3
3
3
3
5. Z. Chen, D. Chao, J. Liu, M. Copley, J. Lin, Z. Shen, G.-T. Kim and S. Passerini,
J. Mater. Chem. A, 2017, 5, 1566915675.
6. X. Ju, H. Huang, W. He, H. Zheng, P. Deng, S. Li, B. Qu and T. Wang, ACS
Sustainable Chem. Eng., 2018, 6, 63126320.
7. Y. Xiao, P.-F. Wang, Y.-X. Yin, Y.-F. Zhu, Y.-B. Niu, X.-D. Zhang, J. Zhang, X.
Yu, X.-D. Guo, B.-H. Zhong and Y.-G. Guo, Adv. Mater., 2018, 30, 1803765.
8. J. Meng, H. Xu, Q. Ma, Z. Li, L. Xu, Z. Chen, B. Cheng and S. Zhong, Electrochim.
Acta, 2019, 309, 326338.
9. J. Zeng, Y. Cui, D. Qu, Q. Zhang, J. Wu, X. Zhu, Z. Li and X. Zhang, ACS Appl.

Page 27 of 30
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/D0TA10608A
Mater. Interfaces, 2016, 8, 2608226090.
4
4
4
0. G. Z. Wei, X. Lu, F. S. Ke, L. Huang, J. T. Li, Z. X. Wang, Z. Y. Zhou and S. G.
Sun, Adv. Mater., 2010, 22, 43644367.
1. F. Fu, G.-L. Xu, Q. Wang, Y.-P. Deng, X. Li, J.-T. Li, L. Huang and S.-G. Sun, J.
Mater. Chem. A, 2013, 1, 38603864.
2. R. Yu, X. Zhang, T. Liu, X. Xu, Y. Huang, G. Wang, X. Wang, H. Shu and X.
Yang, ACS Sustainable Chem. Eng., 2017, 5, 89708981.
4
4
3. J. J. N. Rodriguez-Carvajal, 2001, 26, 12.
4. G. Ma, S. Li, W. Zhang, Z. Yang, S. Liu, X. Fan, F. Chen, Y. Tian, W. Zhang, S.
Yang and M. Li, Angew. Chem., Int. Ed., 2016, 55, 36673671.
5. J. Zhao, W. Zhang, A. Huq, S. T. Misture, B. Zhang, S. Guo, L. Wu, Y. Zhu, Z.
Chen, K. Amine, F. Pan, J. Bai and F. Wang, Adv. Energy Mater., 2017, 7,
4
1
601266.
4
4
4
4
5
6. H. Yu, Y.-G. So, Y. Ren, T. Wu, G. Guo, R. Xiao, J. Lu, H. Li, Y. Yang, H. Zhou,
R. Wang, K. Amine and Y. Ikuhara, J. Am. Chem. Soc., 2018, 140, 1527915289.
7. L. Zhang, N. Li, B. Wu, H. Xu, L. Wang, X.-Q. Yang and F. Wu, Nano Lett., 2015,
1
5, 656661.
8. M. Xu, L. Fei, W. Zhang, T. Li, W. Lu, N. Zhang, Y. Lai, Z. Zhang, J. Fang, K.
Zhang, J. Li and H. Huang, Nano Lett., 2017, 17, 16701677.
9. M. Chen, X. Jin, Z. Chen, Y. Zhong, Y. Liao, Y. Qiu, G. Cao and W. Li, J. Mater.
Chem. A, 2019, 7, 1312013129.
0. M. Jiang, Q. Zhang, X. Wu, Z. Chen, D. L. Danilov, R.-A. Eichel and P. H. L.

Journal of Materials Chemistry A
Page 28 of 30
View Article Online
DOI: 10.1039/D0TA10608A
Notten, ACS Appl. Energy Mater., 2020, 3, 65836590.
5
5
5
1. S. Zhao, Z. Wang, Y. He, B. Jiang, Y. Harn, X. Liu, F. Yu, F. Feng, Q. Shen and
Z. Lin, ACS Energy Lett., 2016, 2, 111116.
2. S. Zhao, Z. Wang, Y. He, H. Jiang, Y. W. Harn, X. Liu, C. Su, H. Jin, Y. Li, S.
Wang, Q. Shen and Z. Lin, Adv. Energy Mater., 2019, 9, 1901093.
3. S.-U. Woo, C. S. Yoon, K. Amine, I. Belharouak and Y.-K. Sun, J .Electrochem.
Soc., 2007, 154, A1005.
5
5
4. E. Flores, P. Novák, U. Aschauer and E. Berg, Chem. Mater., 2019, 32, 186194.
5. H. Li, A. Liu, N. Zhang, Y. Wang, S. Yin, H. Wu and J. R. Dahn, Chem. Mater.,
2
019, 31, 75747583.
5
5
5
5
6
6
6. K. Sahni, M. Ashuri, Q. He, R. Sahore, I. D. Bloom, Y. Liu, J. A. Kaduk and L. L.
Shaw, Electrochim. Acta, 2019, 301, 822.
7. F. Xin, H. Zhou, X. Chen, M. Zuba, N. Chernova, G. Zhou and M. S. Whittingham,
ACS Appl. Mater. Interfaces, 2019, 11, 3488934894.
8. H.-H. Ryu, K.-J. Park, C. S. Yoon and Y.-K. Sun, Chem. Mater., 2018, 30,
1
1551163.
9. H. H. Sun, H.-H. Ryu, U.-H. Kim, J. A. Weeks, A. Heller, Y.-K. Sun and C. B.
Mullins, ACS Energy Lett., 2020, 5, 11361146.
0. Z. Shen, L. Cao, C. D. Rahn and C. Y. Wang, J. Electrochem. Soc., 2013, 160,
A1842A1846.
1. H. Zhou, F. Xin, B. Pei and M. S. Whittingham, ACS Energy Lett., 2019, 4,
1
9021906.

Page 29 of 30
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/D0TA10608A
6
2. Y. T. Ma, P. F. Liu, Q. S. Xie, G. B. Zhang, H. F. Zheng, Y. X. Cai, Z. Li, L. S.
Wang, Z. Z. Zhu, L. Q. Mai and D. L. Peng, Nano Energy, 2019, 59, 184196.