New promising lithium malonatoborate salts for high voltage lithium ion batteries

Article abstract of DOI:10.1039/c6ta07757a

Three new lithium salts, lithium difluoro-2-methyl-2-fluoromalonatoborate (LiDFMFMB), lithium difluoro-2-ethyl-2-fluoromalonatoborate (LiDFEFMB), and lithium difluoro-2-propyl-2-fluoromalonatoborate (LiDFPFMB), have been synthesized and evaluated for application in lithium ion batteries. These new salts are soluble in a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (1:2 by wt) and 1.0 M salt solutions can be easily prepared. The ionic conductivities of these new salts are close to those of LiBF₄ and LiPF₆. Cyclic voltammograms reveal that these new salt based electrolytes can passivate both natural graphite and high voltage spinel LiNi_0.5Mn_1.5O₄ (LNMO) to form effective solid electrolyte interphases (SEIs). In addition, these new salt-based electrolytes exhibit good cycling stability with high coulombic efficiencies in both LiNi_0.5Mn_1.5O₄ and graphite based half-cells and full cells.

Full text of DOI:10.1039/c6ta07757a

View Article Online
View Journal
Journal of
Materials Chemistry A
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: X. Sun, S. Wan, H.
Guan, Y. Fang, K. S. Reeves, M. Chi and S. Dai, J. Mater. Chem. A, 2016, DOI: 10.1039/C6TA07757A.
This is an Accepted Manuscript, which has been through the
Volume
4 Number 1 7 January 2016 Pages 1–330
Royal Society of Chemistry peer review process and has been
accepted for publication.
Journal of
Materials Chemistry A
Accepted Manuscripts are published online shortly after
Materials for energy and sustainability
www.rsc.org/MaterialsA
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
author guidelines.
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, outlined
in our author and reviewer resource centre, 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
PAPER
Kun Chang, Zhaorong Chang et al.
Bubble-template-assisted synthesis of hollow fullerene-like
MoS2 nanocages as a lithium ion battery anode material
rsc.li/materials-a

Page 1 of 8
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/C6TA07757A
Journal Name
RSCPublishing
ARTICLE
New Promising Lithium Malonatoborate Salts for
High Voltage Lithium Ion Batteries
Cite this: DOI: 10.1039/x0xx00000x
Received 00th January 2012,
Accepted 00th January 2012
DOI: 10.1039/x0xx00000x
www.rsc.org/
XiaoꢀGuang Sun,a* Shun Wan,a Hongyu Guang,b Youxing Fang,ac Kimberly
Shawn Reeves,d Miaofang Chi,d Sheng Daiac
Three new lithium salts, lithium difluoroꢀ2ꢀmethylꢀ2ꢀfluoromalonaoborate (LiDFMFMB), lithium
difluoroꢀ2ꢀethylꢀ2ꢀfluoromalonaoborate
(LiDFEFMB),
and
lithium
difluoroꢀ2ꢀpropylꢀ2ꢀfluoro
malonaoborate (LiDFPFMB), have been synthesized and evaluated for application in lithium ion batteries.
These new salts are soluble in a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC)
(1:2 by wt.) and 1.0 M salt solutions can be easily prepared. The ionic conductivities of these new salts
are close to those of LiBF4 and LiPF6. Cyclic voltammograms reveal that these new salt based electrolytes
can passivate both natural graphite and high voltage spinel LiNi0.5Mn1.5O4 (LNMO) to form effective solid
electrolyte interphases (SEIs). In addition, these new salts based electrolytes exhibit good cycling stability
with high coulombic efficiencies in both LiNi0.5Mn1.5O4 and graphite based halfꢀcells and full cells.
Compared with the wellꢀstudied LiBOB, its close analog lithium
1. Introduction
Synthesis of new lithium salts has remained as a challenging bis(malonato) borate (LiBMB) has rarely been studied due to its
task for developing new electrolytes for rechargeable lithium insolubility in common carbonate solvents.18 However, the presence
ion batteries,1ꢀ4 as the lithium salts not only supply the needed of two hydrogens on the Cꢀ2 position of the BMB anion also offers
lithium ion but also dictate ionic conductivity, electrochemical opportunity to tune its property by substitution chemistry that not
window, and even solid electrolyte interphase (SEI) formation only can enhance the salt solubility in organic solvents but also can
at the electrode surfaces. Although the current commercial significantly improve the cell cycling performance.30ꢀ39 For example,
lithium salt, LiPF6, has the optimum combination of ionic we have synthesized lithium bis(2ꢀmethylꢀ2ꢀfluoromalonato) borate
conductivity, ion dissociation, electrochemical window, and (LiBMFMB), which exhibited good cycling performance in both
electrode interfacial properties, it also has several drawbacks, LiNi0.5Mn1.5O4 and graphite based halfꢀcells. 39 Because of replacing
particularly low thermal stability and easy hydrolysis with trace acidic proton with methyl group at the Cꢀ2 position of the anion,
amount of moisture to release harmful and toxic HF, causing LiBMFMB has better cycling performance than lithium bis(2ꢀ
6
transition metal dissolution.5, The latter will lead to the fluoromalonato)borate (LiBFMB).37 Unfortunately, the ionic
formation of insoluble lithium fluoride, resulting in the increase conductivity of LiBMFMB was still lower than that of LiPF6, due to
of cell impedance and poor cell cycling performance. LiBF4 has the bulkiness of the anion. Inspired by the favourable effect of
better thermal and hydrolysis stability than LiPF6, but it still LiDFOB over LiBOB by simply reducing the anion size, herein we
suffers from poor ion dissociation and has lower ionic report the synthesis and characterization of a hybrid salt of LiBF4
conductivity. In addition, both LiPF6 and LiBF4 have the and LiBMFMB, lithium difluoroꢀ2ꢀmethylꢀ2ꢀfluoromalonatoborate
characteristic equilibrium between LiF and Lewis acid of PF5 (LiDFMFMB) and the analo gs with different alkyl chain lengths at
and BF3, respectively. These Lewis acids can initiate the Cꢀ2 position of the anion.
polymerization of carbonate solvents at higher temperatures.6, 7
To improve thermal stability and ionic conductivity,
perfluoroalkyl group substituted LiPF6 and LiBF4 have been
synthesized.8ꢀ12 Among different thermally stable lithium
orthoborate salts13ꢀ21 lithium bis(oxalato)borate (LiBOB) is
O
O
O
O
OH
O
O
ONa
EtOH
NaOH
F
F
F
Na, EtOH
Br
F
HCl
R
H
R
R
R
OH
O
O
ONa
O
O
O
O
O
F
O
unique because it can form effective SEI on the surface of
O
F
Li+
OTMS
LiBF4
Acetonitrile
23
LiDFMFMB, R = Methyl
LiDFEFMB, R = Ethyl
LiDFPFMB, R = Propyl
graphite electrode.22,
Unfortunately, LiBOB has limited
TMSCl
reflux
F
B
R
O
R
F
O
OTMS
solubility in linear carbonate and its solution has higher
viscosity and lower ionic conductivity than that of LiPF6. Also,
it is found that the SEI formed in LiBOB based electrolyte is
more resistive than that formed in LiPF6 based electrolyte.5 To
mitigate the aforementioned issues of LiBOB, a hybrid salt
between LiBF4 and LiBOB, lithium difluoro(oxalato)borate
(LiDFOB), was synthesized, exhibiting higher ionic
conductivity, high thermal stability and high lithium
transference number, as well as good SEI formation ability.24ꢀ29
O
Scheme 1. Synthesis of LiDFMFMB, LiDFEFMB, and LiDFPFMB
2. Results and discussion
2.1. Ionic conductivity
LiDFMFMB, LiDFEFMB and LiDFPFMB were synthesized by
treating purified bis(trimethylsilyl) 2ꢀmethylꢀ2ꢀfluoromalonate,
bis(trimethylsilyl) 2ꢀethylꢀ2ꢀfluoromalonate and bis(trimethylsilyl)
39
2ꢀpropylꢀ2ꢀfluoromalonate
according to a literature procedure (Scheme 1).
with LiBF4 in anhydrous acetonitrile
33
As previously
This journal is © The Royal Society of Chemistry 2013
J. Name., 2013, 00, 1-3 | 1

Journal of Materials Chemistry A
Page 2 of 8
View Article Online
Journal Name
ARTICLE
DOI: 10.1039/C6TA07757A
reported, the trapped acetonitrile in the salts could be easily removed reduction products, resulting in significant decrease of the
via treatment with EC/DMC (1/2, by wt.).37, 39 These salts are very impedance. Simultaneously, the electrolyte will be oxidized at the
soluble in EC/EMC (1:2 by wt.) and 1.0 M solution can be easily surfaces of the LNMO cathodes and form SEI layers. However, the
prepared. Fig. 1 shows the temperature dependence of the ionic impedance at the anode side is so dominant that its significant
conductivities of 1.0 M solutions of the new salts in ECꢀEMC. For decrease disguises the impedance increase at the cathode side,
comparison, the ionic conductivities of 1.0 M solutions of LiBF4 and leading to continual decrease in the total cell impedances, as shown
LiPF6 in the same solvent mixture were also measured. As shown in in Fig. S2. However, for the cell based on LiDFPFMB the total cell
Fig. 1, the temperature dependence of the ionic conductivities can be
described by the wellꢀknown Vogel–Fulcher–Tamman (VFT)
equation:40ꢀ42
impedance dramatically decreases from 226 ꢀ before cycling to 60
ꢀ after the first cycle, followed by gradual increase to 113 ꢀ and
then decrease to 86 ꢀ after five CV cycles. The EIS data reveal that
the SEI formed in the LiDFPFMB based electrolyte is not stable as
compared to those of LiDFMFMB and LiDFEFMB, consistent with
the CVs shown in Fig. 2c.
σ = σ0exp[−B/(T− T0)]
(1)
1
where σ0 (S cm− ) is a constant,
B (K) is the pseudoꢀactivation
2.0
energy, and T0 (K) is the vanishing ion mobility temperature.
Generally, the ionic conductivity follows the order of
LiDFMFMB > LiDFEFMB > LiDFPFMB, consistent with the
decreasing mobility of the anions due to the increase of the
alkyl chain length on the Cꢀ2 position of the anion. More
importantly, the ionic conductivity of 1.0 M LiDFMFMB at 20
oC is 2.24 x 10ꢀ3 S cmꢀ1, which is same as those of LiBF4 and
LiPF6, justifying our initial strategy of reducing the anion size
and improving the ionic conductivity.
a
1.5
1st Cycle
2nd Cycle
3rd Cycle
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 5.2
E / V vs Li / Li+
2.0
1.5
-2.0
-2.2
b
1.0
1st Cycle
2nd Cycle
3rd Cycle
20 oC
0.5
-2.4
0.0
-0.5
-1.0
-1.5
-2.0
-2.6
LiBF4
-2.8
LiPF6
LiDFMFMB
LiDFEFMB
LiDFPFMB
-3.0
-3.2
-3.4
2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 5.2
E / V vs Li / Li+
2.0
1.5
c
2.6
2.8
3.0
3.2
3.4
3.6
3.8
1000 / T ( )
K-1
1st Cycle
2nd Cycle
3rd Cycle
1.0
0.5
Fig. 1. The temperature dependence of ionic conductivities of 1.0 M
0.0
salt solutions in ECꢀEMC (1/2 by wt.).
-0.5
-1.0
-1.5
-2.0
2.2. Cyclic Voltammograms
Fig. 2 shows the cyclic voltammograms (CVs) of a LNMO
electrode in the three salts based electrolytes at a scan rate of 0.05
mV sꢀ1. In the initial anodic scan there is one minor oxidation peak
at 4.10 V and two major oxidation peaks at 4.78 and 4.84 V,
corresponding to the oxidation of Mn3+ to Mn4+, Ni2+ to Ni3+ and
Ni3+ to Ni4+, respectively. In the cathodic scan the major reduction
2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 5.2
E / V vs Li / Li+
Fig. 2. Cyclic voltammograms (CVs) of LNMO in (a) 1.0M
LiDFMFMB, (b) 1.0M LiDFEFMB, and (c) 1.0 M LiDFPFMB in
ECꢀEMC (1/2 by wt.) at a scan rate of 0.05 mV/s. Lithium is used as
both counter and reference electrode.
peak appears at 4.60 V with a clear shoulder peak at 4.66 V, whereas
the minor reduction peak appears at 3.95 V.
43ꢀ45
Comparing the
anodic peaks corresponding to the oxidation of Ni3+ to Ni4+ at high
voltage, the cell based on LiDFPFMB show noticeably intensity
increase from 2nd to 5th cycle (more CV cycles are shown in Fig. S1),
while the cells based on LiDFMFMB and LiDFEFMB exhibit good
overlap of the peaks. These results suggest that the cells based on
LiDFMFMB and LiDFEFMB form functional SEIs on the cathode
surfaces more quickly than that of LiDFPFMB, which is supported
by the cycling data shown later. During the first five CV cycles
electrochemical impedance spectroscopy (EIS) was also monitored
to reveal more details on the SEI formation. The large cell
impedances before cycling are mainly due to the anode electrode,
which are covered with resistive oxide layers, as they were not
scratched before cell assembling. During cycling the resistive oxide
layer is gradually replaced with more lithium ion conductive
Fig. 3 shows the CVs of a graphite electrode in the three salts
based electrolytes at a scan rate of 0.05 mV sꢀ1. Unlike the case of
LiBOB where a conspicuous reduction peak is usually observed at
46, 47
1.75 V,
there are only tiny reduction peaks around 1.65 V for
these new salts based electrolytes, similar to that observed for the
39
LiBMFMB based electrolyte. Taking a closer look at the insets of
Fig. 3, it seems that the reduction feature of the electrolyte is salt
dependent. For example, for LiDFMFMB based electrolyte, the
major reduction peak appears at 1.15 V with a minor peak at 0.75 V;
for LiDFEFMB based electrolyte, the major reduction peak appears
at 1.0 V with shoulder peaks at 1.15 and 0.75 V, respectively;
whereas for LiDFPFMB based electrolyte, the major reduction peak
appears at 0.9 V with a minor peak at 1.15 V. Generally, the
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

Page 3 of 8
Journal Name
Journal of Materials Chemistry A
View Article Online
ARTICLE
DOI: 10.1039/C6TA07757A
reduction peaks above 1.0 V can be attributed to the bulk reduction less stable than LiPF6. It is also noted that at 5.2 V, the leakage
48
of the carbonate solvents on the surface of the graphite electrode,
current of
whereas the small peak at 0.75 V can be attributed to the reduction LiPF6 tends to increase with time while those of the borate salts
of the solvents (mainly EC) that are coꢀintercalated with lithium into decrease with time, suggesting that additional side reactions are
the graphene layer.49ꢀ52 Although different reduction features are triggered in the LiPF6 based electrolyte or LiPF6 starts to decompose
observed for the three salts based electrolytes during the first CV at this potential. The above results confirm that these new salts could
cycle, the reduction peaks all disappear in the following cycles support high voltage cathode with a cutꢀoff voltage of 4.9 V. The
(insets of Fig. 3 and more cycles are shown in Fig. S3), instead less stable of the lithium borate salts than LiPF6 also support
reversible lithium intercalation and deꢀintercalation peaks are previous efforts of using lithium borate salts as additives for LiPF6
observed below 0.20 V and at 0.36 V, respectively. These CVs based electrolytes, which could passivate high voltage cathodes and
indicate that these new salts based electrolytes can passivate graphite support long cycling stability.54ꢀ56
electrode to support reversible lithium intercalation/deꢀintercalation.
EISs were also monitored for the three salts based electrolytes during
Figs. 5a, c, and e show the chargeꢀdischarge profiles of the first
the first five CV cycles, which are shown in Fig.S4. Similar to those two cycles of LNMO||Li halfꢀcells under a current rate of C/5 in
observed in LNMO based cells, the cell impedances before cycling LiDFMFMB, LiDFEFMB, and LiDFPFMB based electrolyte,
are quite different due to different surface layers on the lithium respectively. The initial charge (Li deꢀintercalation) and discharge
metal, but they all decrease significantly after the first cycle, (Li intercalation) capacities are 138.8 and 120.1 mAh gꢀ1, 134.3 and
followed by gradual decrease and then increase to 43.85, 33.26, and 118.4 mAh gꢀ1, and 129.5 and 112.3 mAh gꢀ1 in LiDFMFMB,
LiDFEFMB, and LiDFPFMB based electrolyte, resulting in initial
coulombic efficiencies of 0.865, 0.880, and 0.867, respectively.
These low initial coulombic efficiencies are mainly due to the
electrolyte oxidation under a high voltage of 4.7 V and the SEI
formation on the cathode surface.5 During the second cycle, the
discharge capacities increase while the charge capacities decrease,
resulting in improved coulombic efficiencies of 0.940, 0.952, and
0.951 in LiDFMFMB, LiDFEFMB, and LiDFPFMB based
electrolyte, respectively. After the first two formation cycles, the
long cycling stability of these electrolytes were evaluated under a
high current rate of C/2. As shown in Fig. 5b, d, and f, the charge
and discharge capacities gradually decrease with cycling, and after
100 cycles they decrease to 104.7 and 103.2 mAh gꢀ1, 101.8 and
100.5 mAh gꢀ1, and 96.0 and 94.9 mAh gꢀ1 in LiDFMFMB,
LiDFEFMB and LiDFPFMB based electrolyte, respectively. The
capacity retention is 0.904, 0.897, and 0.905 in LiDFMFMB,
LiDFEFMB and LiDFPFMB based electrolyte, respectively. High
capacity and good capacity retention is achieved in LiDFMFMB
based electrolyte. It is noted in LiDFPFMB based electrolyte, the
capacities initially drop quickly and they are stabilized after 10
cycles, which is consistent with the CV data shown in Fig. 2c.
Fig.S3 compares the cell impedance before cycling and after
cycling. The total cell impedance in LiDFMFMB, LiDFEFMB and
LiDFPFMB based electrolyte increases from 145.0, 143.5 and 169.3
ꢁ before
40.65 ꢀ after
5 cycles for LiDFMFMB, LiDFEFMB, and
LiDFPFMB based electrolyte, respectively.
1.0
0.000
a
-0.005
0.8
1st Cycle
2nd Cycle
-0.010
0.6
-0.015
-0.020
0.4
-0.025
0.2
-0.030
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.0
-0.2
-0.4
-0.6
-0.8
1st Cycle
2nd Cycle
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
E / V vs Li / Li+
1.0
0.8
0.00
b
-0.01
-0.02
-0.03
-0.04
1st Cycle
2nd Cycle
0.6
0.4
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.2
0.0
-0.2
-0.4
-0.6
-0.8
1st Cycle
2nd Cycle
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
E / V vs Li / Li+
1.0
0.8
c
0.00
-0.01
-0.02
-0.03
-0.04
-0.05
-0.06
1st Cycle
2nd Cycle
0.6
0.45
0.40
0.4
0.2
0.0
0.5
1.0
1.5
2.0
2.5
0.0
LiDFMFMB
0.35
-0.2
-0.4
-0.6
-0.8
-1.0
LiDFEFMB
1st Cycle
2nd Cycle
0.30
0.25
0.20
0.15
0.10
0.05
0.00
LiDFPFMB
LiPF6
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
E / V vs Li / Li+
4.9 V
5.0 V
5.1 V
5.2 V
Fig. 3. Cyclic voltammograms (CVs) of the graphite in (a) 1.0M
LiDFMFMB, (b) 1.0M LiDFEFMB, and (c) 1.0 M LiDFPFMB electrolyte at
a scan rate of 0.05 mV/s. Lithium is used as both counter and reference
electrodes.
0
5
10
15
20
25
30
35
40
2.3. LNMO||Li and NG||Li Half-cell performance
Time / hr
Before evaluation of halfꢀcell performance, we have further
evaluated the oxidation stability of the electrolyte using
electrochemical floating test. As shown in Fig.4, all three lithium
Fig. 4. Electrochemical floating test of different lithium salts electrolytes on
LNMO electrode.
53
salts exhibit similar current profile. However, they all have higher
leakage currents than LiPF6, indicating these new borate salts are
cycling to 166.8, 466.6, and 539.5 ꢁ after 100 cycles, respectively.
The EISs after cycling clearly show two semicircles at high and
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 3

Journal of Materials Chemistry A
Page 4 of 8
View Article Online
Journal Name
ARTICLE
DOI: 10.1039/C6TA07757A
medium frequencies corresponding to resistance of SEI layer and LiDFMFMB, LiDFEFMB, and LiDFPFMB based electrolyte,
that of Faradic charge transfer, respectively.57, 58 It is also noted that respectively. After the first two SEI formation cycles, long cycling
the cell impedance increase in these electrolytes is much less than stability of these electrolytes was evaluated under a high current rate
that in LiBMFMB based electrolyte,39 which may be attributed to of C/5. As shown in Fig. 5b, d, and f, the discharge and charge
higher ionic conductivities, less electrolyte decomposition and capacities gradually decrease with cycling, and after 60 cycles they
thinner SEI layer of the former. Particularly, the cell impedance in decrease to 308.4 and 305.4 mAh gꢀ1, 319.6 and 318.4 mAh gꢀ1, and
LiDFMFMB based electrolyte is much less than those in 331.6 and 327.6 mAh gꢀ1 in LiDFMFMB, LiDFEFMB and
LiDFEFMB and LiDFPFMB based electrolytes, indicating that LiDFPFMB based electrolyte, respectively. The
shorter alkyl chain at the Cꢀ2 position of the salt anion not only
offers higher ionic conductivity but also provides better SEI
chemistry with lower cell impedance.
In addition to long cycling stability, these new lithium salts also
exhibit good rate capability. As shown in Fig.6, the reversible
capacities of LNMO||NG halfꢀcells in the three salts are all around
260
240
220
200
180
160
140
120
100
80
105
100
95
90
85
80
75
70
65
60
55
50
45
40
128, 126, 120, 106, and 60 mAh gꢀ1 under C/10, C/5, C/2, 1C, and
2C, respectively. It is noted that the capacities at 2C are much lower
than those at other current densities, indicating 1C is the highest
current density for these new salts in practical applications.
a
C/10
C/5
C/5
C/2
1C
2C
Charge
Discharge
60
40
20
0
160
140
120
100
80
100
95
90
85
80
75
70
65
60
5.0
4.5
4.0
3.5
3.0
2.5
Coulombic efficiency
a
c
e
b
0
5
10
15
20
25
30
Cycle number
260
105
Charge
Discharge
Coulombic efficiency
1st Cycle; CE = 0.865
2nd Cycle; CE = 0.940
240
220
200
180
160
140
120
100
80
60
40
20
0
100
95
90
85
80
75
70
65
60
55
50
45
40
b
60
C/10
40
0
20
40
60
80
100 120 140
0
20
40
60
80
100
C/5
C/5
C/2
1C
Capacity / mAh g-1
Cycle number
160
140
120
100
80
100
95
90
85
80
75
70
65
60
5.0
4.5
4.0
3.5
3.0
2.5
Charge
Discharge
Coulombic efficiency
2C
d
0
5
10
15
20
25
30
Cycle number
1st Cycle; CE = 0.880
2nd Cycle; CE = 0.952
Charge
Discharge
260
105
Coulombic efficiency
240
220
200
180
160
140
120
100
80
100
95
90
85
80
75
70
65
60
55
50
45
40
c
60
40
0
20
40
60
80
100 120 140
0
10 20 30 40 50 60 70 80 90 100
Capacity / mAh g-1
Cycle number
C/10
C/5
C/5
160
140
120
100
80
100
95
90
85
80
C/2
1C
5.0
4.5
4.0
3.5
3.0
2.5
f
2C
Charge
Discharge
Coulombic efficiency
60
40
20
0
1st Cycle; CE = 0.867
2nd Cycle; CE = 0.951
Charge
Discharge
75
70
65
60
0
5
10
15
20
25
30
Coulombic efficiency
60
Cycle number
40
0
20
40
60
80
100 120 140
0
20
40
60
80
100
Fig. 6. Chargeꢀdischarge capacities and coulombic efficiencies of
LNMO||Li halfꢀcells in 1.0 M (a) LiDFMFMB, (b) LiDFEFMB, and (c)
LiDFPFMB electrolyte under different current rates.
Capacity / mAh g-1
Cycle number
Fig. 5. Chargeꢀdischarge profile (a, c, and e) and chargeꢀdischarge capacities
and coulombic efficiencies (b, d, and f) of LNMO||Li halfꢀcells in 1.0 M (a
and b) LiDFMFMB, (c and d) LiDFEFMB, and (e and f) LiDFPFMB
electrolyte under the current rate of C/5 (a, c, and e) and C/2 (b, d, and f),
respectively.
capacity retention is 0.933, 0.984, and 0.992 for LiDFMFMB,
LiDFEFMB and LiDFPFMB based cell, respectively. The best
capacity retention is obtained for LiDFPFMB based electrolyte,
which is in direct contrast to the results obtained on the
LiNi0.5Mn1.5O4 based halfꢀcells. To further analysis of the cycling
data, EIS was also measured before and after cycling. As shown in
Fig. S6, the total cell impedance in LiDFMFMB, LiDFEFMB and
LiDFPFMB based electrolyte is 107.6, 108.6 and 89.4 ꢁ before
cycling and changes to 108.8, 109.6, and 86.2 ꢁ after 60 cycles,
respectively. It should be noted that even though the cell impedance
before and after cycling is very similar, it clearly evolves through a
gradual changing process as revealed in the EISs during the CV
cycles, i.e., decreases significantly after the first cycle, and then
decreases gradually until fourth cycle, and finally increases with
cycling. Taking a closer look at the EIS data,57, 58 it is noticed that
Figs. 7a, c, and e show the chargeꢀdischarge profiles of the first
two cycles of NG||Li halfꢀcells under a current rate of C/10 in
LiDFMFMB, LiDFEFM, and LiDFPFMB based electrolyte,
respectively. The initial discharge (Li intercalation) and charge (Li
deꢀintercalation) capacities are 382.2 and 337.9mAh gꢀ1, 385.9 and
335.8 mAh gꢀ1, and 396.5 and 336.7 mAh gꢀ1 in LiDFMFMB,
LiDFEFMB, and LiDFPFMB based electrolyte, resulting in initial
coulombic efficiencies of 0.884, 0.870, and 0.849, respectively.
During the second cycle the discharge capacities significantly
decrease while the charge capacities barely increase, resulting in
improved coulombic efficiencies of 0.967, 0.967, and 0.958 in
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

Page 5 of 8
Journal Name
Journal of Materials Chemistry A
View Article Online
ARTICLE
DOI: 10.1039/C6TA07757A
the bulk resistance increases from 9.6, 10.7 and 8.5 ꢁ before cycling the cathode during the SEI formation on the surface of the graphite
to 16.0, 18.5 and 18.5 ꢁ after 60 cycles in LiDFMFMB, LiDFEFMB electrodes. Similar to that observed in the halfꢀcells, the reversible
and LiDFPFMB based electrolyte, respectively. The increase in bulk capacities and coulombic efficiencies increase in the second cycle
resistance can be attributed to the consumption of the electrolyte for due to the successful SEI formation during the first cycle. After 50
reaction with lithium electrode, SEI formation on the graphite cycles, the reversible capacities are 87.2, 95.3, and 78.2 mAh gꢀ1 for
electrode, resulting in increase of salt concentration and decrease of LiDFMFMB, LiDFEFMB, and LiDFPFMB based electrolyte,
ionic conductivity. It is also noted that the combined resistance of respectively.
SEI and Faradic charge transfer is 92.8, 91.1 and 67.7 ꢁ in
LiDFMFMB, LiDFEFMB and LiDFPFMB based electrolyte,
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
200
180
160
140
120
100
80
105
100
95
90
85
80
75
70
65
60
55
50
a
b
respectively. The low cell impedance as well as low combined
resistance of SEI and Faradic charge transfer in LiDFPFMB based
electrolyte is consistent with the best cycling performance shown in
Fig.5f.
C/5
C/3
60
Charge
Discharge
Coulombic efficiency
40
1st Cycle; CE = 75.3
2nd Cycle; CE = 92.9
2.5
400
350
300
250
200
100
95
90
85
80
75
70
65
60
20
a
b
0
2.0
1.5
1.0
0.5
0.0
0
5
10 15 20 25 30 35 40 45 50
0
20
40
60
80 100 120 140 160
Capacity / mAh g-1
Cycle number
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
200
105
1st Cycle; CE = 0.884
2nd Cycle; CE = 0.967
c
d
100
95
90
85
80
75
70
65
60
55
50
Charge
Discharge
Coulombic efficiency
150
100
50
0
50 100 150 200 250 300 350 400
0
10
20
30
40
50
60
Capacity / mAh g-1
Cycle number
Charge
Discharge
1st Cycle; CE = 78.1
2nd Cycle; CE = 94.9
Coulombic efficiency
2.5
2.0
1.5
1.0
0.5
0.0
400
350
300
250
200
100
0
0
5
f
10 15 20 25 30 35 40 45 50
c
0
20
40
60
80 100 120 140 160
d
95
90
85
80
75
70
65
60
Capacity / mAh g-1
Cycle number
200
105
100
95
90
85
80
75
70
65
60
55
50
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
e
180
160
140
120
100
80
Charge
Discharge
Coulombic efficiency
C/5
1st Cycle; CE = 0.870
2nd Cycle; CE = 0.967
C/3
60
Charge
Discharge
40
1st Cycle; CE = 74.2
2nd Cycle; CE = 94.2
0
50 100 150 200 250 300 350 400
0
10
20
30
40
50
60
20
Coulombic efficiency
Capacity / mAh g-1
Cycle number
0
0
5
10 15 20 25 30 35 40 45 50
0
20
40
60
80 100 120 140 160
Capacity / mAh g-1
Cycle number
400
350
300
250
200
100
2.5
2.0
1.5
1.0
0.5
0.0
e
95
90
85
80
75
70
65
60
f
Fig. 8. Chargeꢀdischarge profile (a, c, and e) and Chargeꢀdischarge
capacities and coulombic efficiencies (b, d, and f) of the LNMO||NG
fullꢀcell in 1.0 M (a and b) LiDFMFMB, (c and d) LiDFEFMB, and (e
and f) LiDFPFMB electrolyte under the current rate of C/5 (a, c, and e)
and C/3 (b, d, and f).
Charge
Discharge
1st Cycle; CE = 0.849
2nd Cycle; CE = 0.958
Coulombic efficiency
After 50 cycles, the cells were dissembled inside the
glovebox and the electrodes were washed with anhydrous
DMC, dried and further analysed by scanning electron
microscopy (SEM), with the surface species being surveyed
with energy dispersive Xꢀray (EDX) spectroscopy. Fig. 9 shows
the SEM images of the pristine LNMO and NG electrodes and
those cycled in the three lithium salts based electrolytes.
Compared to the pristine NG and LNMO electrodes, the
surfaces of the cycled NG and LNMO electrodes are clearly
covered with SEI layers from the electrolyte reduction and
oxidation, respectively. Comparatively, the SEI layers are much
thicker on the NG electrodes than those on the LNMO
electrodes, as supported by the EDX data shown in Fig.S7. For
example, carbon is reduced from 87.56 wt% in the pristine NG
electrode to 58.52, 62.79, and 66.32 wt% in those cycled in
LiDFMBMB, LiDFEFMB, and LiDFPFMB based electrolyte,
0
10
20
30
40
50
60
0
50 100 150 200 250 300 350 400
Capacity / mAh g-1
Cycle number
Fig. 7. Chargeꢀdischarge profile (a, c, and e) and chargeꢀdischarge capacities
and coulombic efficiencies (b, d, and f) of the NG||Li halfꢀcell in 1.0 M (a
and b) LiDFMFMB, (c and d) LiDFEFMB, and (e and f) LiDFPFMB
electrolyte under the current rate of C/10 (a, c, and e) and C/5 (b, d, and f)
respectively.
2.4. LiNi0.5Mn1.5O4||NG Full-cell performance
Based on the excellent performance of the new salts electrolytes
in LiNi0.5Mn1.5O4||Li and NG||Li Halfꢀcells, we have further
evaluated their performance in LiNi0.5Mn1.5O4||NG full cells. These
cells were cycled under a current rate of C/5 for the first five cycles,
followed by a current rate of C/3 for 50 cycles. Figs. 8a, c, and e
show the chargeꢀdischarge profiles of the first two cycles of
LNMO||NG fullꢀcells under the current rate of C/5 in LiDFMFMB,
LiDFEFMB, and LiDFPFMB based electrolyte, respectively. The
initial charge (Li deꢀintercalation) and discharge (Li intercalation)
capacities are 141.8 and 106.8 mAh gꢀ1, 138.7 and 103.0 mAh gꢀ1,
and 134.5 and 105.1 mAh gꢀ1 in LiDFMFMB, LiDFEFMB, and
LiDFPFMB based electrolyte, respectively, resulting in initial
coulombic efficiencies of 0.753, 0.743, and 0.781, respectively. The
lower initial coulombic efficiency in these full cells as well as lower
reversible capacities than the respective halfꢀcells shown in Fig. 5
are apparently due to the consumption of the limited Li source from
respectively.
In the meantime, fluorine is significantly
increased from 2.96 wt% in pristine electrode to 27.4, 21.8, and
15.8 wt% in those cycled in LiDFMBMB, LiDFEFMB, and
LiDFPFMB based electrolyte, respectively. As a comparison,
carbon and fluorine are increased from 30.69 and 9.02 wt% in
the pristine LNMO electrode to 40.37 and 12.89 wt%, 47.99
and 11.19 wt%, and 45.23 and 9.4 wt% in those cycled in
LiDFMBMB, LiDFEFMB, and LiDFPFMB based electrolyte,
respectively. It is also noticed from the EDX data in Fig. S7
that there is trace amount Mn observed in all cycled NG
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 5

Journal of Materials Chemistry A
Page 6 of 8
View Article Online
Journal Name
DOI: 10.1039/C6TAA07R7T5I7CALE
electrodes as compared to the pristine electrode, indicating that grade (moisture less than 50 ppm) and were used without further
some Mn is reduced and migrated from the cathode to the purification. Diethyl 2ꢀfluoromalonate was purchased from
anode during cycling. Nonetheless, the above data show that Synnovator, Inc. Trimethyl borate and trimethylsilyl chloride were
during cycling these new salts are reduced and oxidized at the purchased from Aldrich. Ethylene carbonate (EC), dimethyl
surface of NG and LNMO electrode, respectively, forming carbonate (DMC), ethyl methyl carbonate (EMC), and LiPF6 were
effective SEIs to support reversible cycling.
all purchased from BASF. Natural graphite was obtained from MTI
Corporation.
a
b
3.2. Synthesis
3.2.1. Diethyl 2-alkyl-2-fluoromalonate 39
To a solution of sodium (2.3 g, 0.1 mol) in ethanol (100 ml),
diethyl fluoromalonate (17.8 g, 0.1 mol) was added dropwise. The
mixture was stirred at room temperature until the bubbling of
hydrogen gas was stopped. Alkyl halide (0.1 mol, methyl iodide,
ethyl bromide, or propyl bromide) was added dropwise and the
resulting solution was refluxed for overnight. The solvent was
evaporated and the residue was distilled under reduced pressure to
obtain pure diethyl 2ꢀalkylꢀ2ꢀfluoromalonate.
c
d
Diethyl 2ꢀmethylꢀ2fluoromalonat: 1H NMR (CD3Cl, 400 MHz)
δ ppm: 4.26 (q, 4H), 1.81 (d, 3H), 1.30 (t, 6H).
Diethyl 2ꢀethylꢀ2fluoromalonate: 1H NMR (CD3Cl, 400 MHz)
δ ppm: 4.30 (q, 4H), 2.20 (m, 2H), 1.78 (t, 6H), 1.00 (t, 3H).
Diethyl 2ꢀproylꢀ2fluoromalonate: 1H NMR (CDCl3, 400 MHz)
δ ppm: 4.30 (q, 4H), 2.12 (m, 2H), 1.42 (m, 2H), 1.30 (t, 6H), 0.97
(t, 3H).
e
g
f
3.2.2. Sodium 2-alkyl-2-fluoromalonate 39
Sodium 2ꢀalkylꢀ2ꢀfluoromalonate was synthesized by using the
same procedure of our group.37
Sodium 2ꢀmethylꢀ2ꢀfluoromalonate: Yield: quantitative. 1H
NMR (D2O, 400 MHz) δ ppm: 1.62 (d, 3H).
h
1
Sodium 2ꢀethylꢀ2ꢀfluoromalonate: Yield: quantitative. H NMR
(D2O, 400 MHz) δ ppm: 2.05 (m, 2H), 0.9 (t, 3H).
Sodium 2ꢀpropylꢀ2ꢀfluoromalonate: Yield: quantitative. 1H
NMR (D2O, 400 MHz) δ ppm:2.0 (m, 2H), 1.35 (m, 2H), 0. 9 (t,
3H).
3.2.3. 2-alkyl-2-fluoromalonic acid 39
Fig. 9. SEM images of pristine graphite (a) and LNMO (b) electrode and
cycled graphite (c, e and g) and LNMO (d, f and h) electrodes from the full
cells in Fig. 8 in LiDFMFMB (c and d), LiDFEFMB (e and f), and
LiDFPFMB (g and h) based electrolyte, respectively.
Dried sodium 2ꢀalkylꢀ2ꢀfluoromalonate was dissolved in large
excess of concentrated HCl solution and the heterogeneous solution
was stirred at room temperature overnight. After the reaction was
completed, HCl was removed by vigorous nitrogen bubbling,
followed by rotoꢀevaporating at 80 °C. The concentrated liquid was
dissolved in 500 mL of ether and the pre cipitated NaCl was
removed by filtration. The product was obtained after removing
solvent. 2ꢀmethylꢀ2ꢀfluoromalonic acid: 1H NMR (acetonitrileꢀd3,
400 MHz) δ ppm: 5.4 (s, broad), 1.70 (d, 3H).
Conclusions
In summary, three new half borate lithium salts based on the
hybridization
of
symmetric
lithium
bis(2ꢀalkylꢀ2ꢀ
fluoromalonato)borate and LiBF4 have been successfully synthesized
and evaluated for application in rechargeable lithium ion batteries.
These new salts based electrolytes exhibit similar ionic
conductivities to those of LiBF4 and LiPF6, have good compatibility
with both graphite and high voltage spinel LNMO cathode. In
addition, the new salts based electrolytes show good rate capability
and long cycling stability in both LNMO and NG based halfꢀcells.
More importantly, the new electrolytes also show good cycling
stability in LNMO||NG full cells under a current rate of C/3. The
good cycling performance in both graphite and LiNMO based halfꢀ
cells and full cells demonstrate that these new half salts are
promising candidates for application in rechargeable lithium ion
batteries.
2ꢀethylꢀ2ꢀfluoromalonic acid: 1H NMR (acetonitrileꢀd3, 400
MHz) δ ppm: 3.3 (s, broad), 2.13 (m, 2H), 0.95 (t, 3H).
2ꢀpropylꢀ2ꢀfluoromalonic acid: 1H NMR (acetonitrileꢀd3, 400
MHz) δ ppm: 4.85 (s, broad), 2.10 (m, 2H)), 1.40 (m, 2H), 0.95 (t,
3H).
3.2.4. Bis(trimethylsilyl) 2-alkyl-2-fluoromalonate 39
A mixture of 2ꢀalkylꢀ2ꢀfluoromalonic acid and trimethylsilyl
chloride was reflux for 4 days, during which the byꢀproduct HCl was
removed by vacuum and fresh trimethylsilyl chloride was added
several times. The reaction was monitored by NMR, and when the
highest ratio of the final product to the monoester was observed, the
reaction was stopped. The excess amount of trimethylsilyl chloride
was removed by rotovap and the crude product was further purified
by distillation.
3. Experimental
3.1. Materials
All reactions involving trimethylsilyl functional groups were
carried out under argon atmosphere. All solvents were of anhydrous
6 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

Page 7 of 8
Journal Name
Journal of Materials Chemistry A
View Article Online
ARTICLE
DOI: 10.1039/C6TA07757A
Bis(trimethylsilyl) 2ꢀmethylꢀ2ꢀfluoromalonate: 1H NMR cells were assembled by using a capacity ratio of LNMO/NG as
(CDCl3, 400 MHz) δ ppm: 1.75 (d, 3H), 0.35 (s, 18H). 1.2/1. The coin cells were cycled on an Arbin instrument between
Bis(trimethylsilyl) 2ꢀethylꢀ2ꢀfluoromalonate: H NMR (CDCl3, 3.0 and 4.9 V for LNMO, and between 0.005 and 2.0 V for graphite
1
400 MHz) δ ppm: 2.12 (m, 2H), 0.97 (t, 3H), 0.30 (s, 18H).
electrode under different current rates. CV data were recorded with
Bis(trimethylsilyl) 2ꢀpropylꢀ2ꢀfluoromalonate: 1H NMR LNMO or graphite as the working electrode and lithium as both
(acetoneꢀd6, 400 MHz) δ ppm: 2.08 (m, 2H), 1.43 (m, 2H), 0.97 (t, counter and reference electrode under a scan rate of 0.05 mV s−1.
3H), 0.31 (s, 18H).
The bulk ionic conductivity of the electrolyte solutions were
60
measured as described earlier.59,
Electrochemical impedance
spectroscopy was measured on a Gamry Instrument in the frequency
range from 3 × 105 Hz to 1 Hz with perturbation amplitude of 10
mV. The electrochemical floating test was performed using
LNMO||Li halfꢀcell configuration. The cell was first charged to 4.9
V under a low current rate of C/12, followed by maintaining at 4.9,
5.0, 5.1, and 5.2 V for 10 hours, respectively with current being
monitored. 53
3.2.5. Lithium difluoro-2-n-alkyl-2-fluoromalonatoborate:33
LiBF4 (one equivalent) and bis(trimethylsilyl) 2ꢀnꢀalkylꢀ2ꢀ
fluoromalonate (one equivalents) was mixed in anhydrous
acetonitrile and stirred at room temperature inside glovebox for 12 h.
After the reaction was completed, a homogeneous solution was
formed. The solvent was removed by rotary evaporation at 50 °C
before drying in a vacuum oven at 75 °C for 24 h. Pure white
powder was obtained after washing with anhydrous ether.
Acknowledgements
Research was sponsored by the U.S. Department of Energy, Office
of Science, Office of Basic Energy Sciences, Materials Sciences and
Engineering Division. The electrodes were produced at the U.S.
Department of Energy’s (DOE) CAMP (Cell Analysis, Modeling
and Prototyping) Facility, Argonne National Laboratory. The
CAMP Facility is fully supported by the DOE Vehicle Technologies
Program (VTP) within the core funding of the Applied Battery
Research (ABR) for Transportation Program. The electron
microscopy work was performed through a user project supported by
the ORNL¹s Center for Nanophase Materials Sciences, which is an
Office of Science User Facility.
1
Lithium difluoroꢀ2ꢀnꢀmethylꢀ2ꢀfluoromalonatoborate: H NMR
(DMSOꢀd6, 400 MHz) δ ppm: 1.69 (d, 3H). 11B NMR (DMSOꢀd6,
128.4 MHz) ppm: 1.31. 19F NMR (DMSOꢀd6, 376 MHz) δ ppm: ꢀ
7
159.43 (q), –165.09 (t). Li NMR (DMSOꢀd6, 155.4 MHz) δ ppm: ꢀ
1.03.
Lithium difluoroꢀ2ꢀnꢀethylꢀ2ꢀfluoromalonatoborate: 1H NMR
(DMSOꢀd6, 400 MHz) δ ppm: 2.03 (m, 2H), 0.90 (t, 3H). 11B NMR
(DMSOꢀd6, 128.4 MHz) ppm: 1.30. 19F NMR (DMSOꢀd6, 376 MHz)
7
δ ppm: ꢀ167.76 (t), –165.09 (t). Li NMR (DMSOꢀd6, 155.4 MHz) δ
ppm: ꢀ1.04.
1
Lithium difluoroꢀ2ꢀnꢀpropylꢀ2ꢀfluoromalonatoborate: H NMR
Received: ((will be filled in by the editorial staff))
Revised: ((will be filled in by the editorial staff))
Published online: ((will be filled in by the editorial staff))
(DMSOꢀd6, 400 MHz) δ ppm: 1.98 (m, 2H), 1.33 (m, 2H), 0.89 (t,
3H). 11B NMR (DMSOꢀd6, 128.4 MHz) ppm: 1.29. 19F NMR
7
(DMSOꢀd6, 376 MHz) δ ppm: ꢀ167.76 (t), –165.09 (t). Li NMR
(DMSOꢀd6, 155.4 MHz) δ ppm: ꢀ1.05.
Notes and references
a Chemical Sciences Division, Oak Ridge National Laboratory, One Bethel
Valley Road, Oak Ridge, TN 37831, USA
3.3. Characterization
NMR measurements were performed using a 9.4 Tesla Bruker
Avance NMR spectrometer at Larmor frequencies of 400.1, 376.4,
*Email: sunx@ornl.gov
b Department of Chemistry, Northeast Normal University, 5268 Renmin
Street, Changchun, Jilin 130012, P. R. China
155.3, and 128.4 MHz for H, 19F, Li, and 11B, respectively. The
1
7
chemical shifts of the proton NMR spectra were reported in ppm
relative to tetramethylsilane (TMS) or residual solvent peaks in H
c Department of Chemistry, University of Tennessee, Knoxville, Tennessee
37996, USA
1
d Center for Nanophase Materials Sciences, Oak Ridge National Laboratory,
One Bethel Valley Road, Oak Ridge , TN 37831 , USA
NMR spectra. LiCl, BF3·Et2O, and CF3Cl in DMSOꢀd6 were used as
a
secondary external standard for 7Li, 11B, and 19F NMR,
respectively.
Calculated amount of anhydrous lithium salts were dissolved in
Electronic Supplementary Information (ESI) available: [Cyclic
votammograms, electrochemical impedance spectroscopy]. See
DOI: 10.1039/b000000x/
EC/DMC in an argonꢀfilled glovebox and the solution was then
subjected to high vacuum treatment (10 mtorr) at 50 oC for
overnight, after which only EC was left. Based on the integration of
This manuscript has been authored by UTꢀBattelle, LLC under Contract No.
DEꢀAC05ꢀ00OR22725 with the U.S. Department of Energy. The United
States Government retains and the publisher, by accepting the article for
publication, acknowledges that the United States Government retains a nonꢀ
exclusive, paidꢀup, irrevocable, worldꢀwide license to publish or reproduce
the published form of this manuscript, or allow others to do so, for United
States Government purposes. The Department of Energy will provide public
access to these results of federally sponsored research in accordance with the
DOE Public Access Plan (http://energy.gov/downloads/doeꢀpublicꢀaccessꢀ
plan).
1
the H NMR peaks for the lithium salts and EC, calculated amounts
of EC and EMC were subsequently added to prepare 1.0 M salt
solutions in EC/EMC (1/2 by wt.). The LNMO electrode used in this
experiment was fabricated at the U.S. Department of Energy’s
(DOE) CAMP (Cell Analysis, Modelling and Prototyping) Facility,
Argonne National Laboratory. LNMO was coated on an Al foil and
has a composition of 84 wt. % of active material, 8 wt. % of
conductive carbon C45 and 8 wt. % of PVDF binder. The loading of
LNMO in each electrode is about 14.7 mg cmꢀ2. Graphite electrode
was obtained by casting well homogenized slurry of graphite (92
wt.%), carbon black (2 wt.%), and PVdF (6 wt. %) in Nꢀ
methylpyrrolidone (NMP) on copper foil with a doctor blade. After
solvent evaporation the electrodes were cut into discs with a
diameter of 12 mm and further dried at 110 °C for 24 h. The loading
of graphite in each electrode is in the range of 2 to 3 mg cmꢀ2. All the
samples for the electrochemical tests were assembled in a gloveꢀbox
with oxygen and moisture level below 0.5 ppm. LNMO||NG full
1. R. Younesi, G. M. Veith, P. Johansson, K. Edstrom and T. Vegge,
Energy Environ Sci., 2015, 8(7), 1905ꢀ1922.
2. P. Jankowski, W. Wieczorek and P. Johansson, Phys. Chem. Chem.
Phys., 2016, 16274ꢀ16280.
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 7

Journal of Materials Chemistry A
Page 8 of 8
View Article Online
Journal Name
ARTICLE
DOI: 10.1039/C6TA07757A
3. P. Jankowski, M. Dranka and G. Z. Zukowska, Journal of Physical 39. S. Wan, X. G. Jiang, B. K. Guo, S. Dai, J. B. Goodenough and X. G.
Chemistry C, 2015, 119, 10247ꢀ10254. Sun, Chem. Commun., 2015, 51, 9817ꢀ9820.
4. P. Jankowski, M. Dranka, G. Z. Zukowska and J. Zachara, Journal of 40. H. Tokuda, K. Hayamizu, K. Ishii, M. Susan and M. Watanabe, J Phys.
Physical Chemistry C, 2015, 119, 9108ꢀ9116.
5. K. Xu, Chem. Rev., 2004, 104, 4303ꢀ4417.
6. N. S. Choi, J. G. Han, S. Y. Ha, I. Park and C. K. Back, Rsc Advances,
2015, 5, 2732ꢀ2748.
7. S. E. Sloop, J. K. Pugh, S. Wang, J. B. Kerr and K. Kinoshita,
Electrochem. Solid State Lett., 2001, 4, A42ꢀA44.
8. Z. B. Zhou, M. Takeda and M. Ue, J. Fluorine Chem., 2003, 123, 127ꢀ
131.
Chem. B, 2004, 108, 16593ꢀ16600.
41. H. Tokuda, K. Hayamizu, K. Ishii, M. Susan and M. Watanabe, J. Phys.
Chem. B, 2005, 109, 6103ꢀ6110.
42. H. Tokuda, K. Ishii, M. Susan, S. Tsuzuki, K. Hayamizu and M.
Watanabe, J Phys. Chem. B, 2006, 110, 2833ꢀ2839.
43. Q. M. Zhong, A. Bonakclarpour, M. J. Zhang, Y. Gao and J. R. Dahn, J.
Electrochem. Soc.,, 1997, 144, 205ꢀ213.
44. H. Xia, S. B. Tang, L. Lu, Y. S. Meng and G. Ceder, Electrochimica
Acta, 2007, 52, 2822ꢀ2828.
45. T.ꢀF. Yi and Y.ꢀR. Zhu, Electrochimica Acta, 2008, 53, 3120ꢀ3126.
9. Z. B. Zhou, M. Takeda, T. Fujii and M. Ue, J. Electrochem. Soc., 2005,
152, , A351ꢀA356.
10. H. J. Frohn and V. V. Bardin, Zeitschrift Fur Anorganische Und 46. J. C. Panitz, U. Wietelmann, M. Wachtler, S. Stroebele and M.
Allgemeine Chemie, 2001, 627, 15ꢀ16. WohlfahrtꢀMehrens, J. of Power Sources, 2006, 153, 396ꢀ401.
11. V. V. Bardin and H. J. Frohn, Main Group Metal Chemistry, 2002, 25, 47. K. Xu, S. Zhang and T. R. Jow, Electrochem. Solid State Lett., 2003, 6,
589ꢀ613. A117ꢀA120.
12. V. V. Bardin, S. G. Idemskaya and H. J. Frohn, Zeitschrift Fur 48. X. R. Zhang, R. Kostecki, T. J. Richardson, J. K. Pugh and P. N. Ross,
Anorganische Und Allgemeine Chemie, 2002, 628, 883ꢀ890. Jr., J. Electrochem. Soc. , 2001, 148, A1341ꢀA1345.
13. J. W. Barthel, M.; Buestrich, R.; Gores, H. J. , J. Electrochem. Soc., 49. S. K. Jeong, M. Inaba, Y. Iriyama, T. Abe and Z. Ogumi, Electrochem.
1995, 142, 2527ꢀ2531. Solid State Lett., 2003, 6, A13ꢀA15.
14. J. Barthel, R. Buestrich, E. Carl and H. J. Gores, J. Electrochem. Soc., 50. S. K. Jeong, M. Inaba, Y. Iriyama, T. Abe and Z. Ogumi, J. Power
1996, 143, 3572ꢀ3575. Sources, 2008, 175, 540ꢀ546.
15. J. Barthel, M. Schmidt and H. J. Gores, J. Electrochem. Soc., 1998, 145, 51. S. K. Jeong, M. Inaba, Y. Iriyama, T. Abe and Z. Ogumi, Electrochimica
L17ꢀL20. Acta, 2002, 47, 1975ꢀ1982.
16. J. Barthel, A. Schmid and H. J. Gores, J. Electrochem. Soc., 2000, 147, 52. T. Fukutsuka, S. Hasegawa, Y. Matsuo, Y. Sugie, T. Abe and Z. Ogumi,
21ꢀ24. J Power Sources, 2005, 146, 151ꢀ155.
17. U. Lischka, U. Wietelmann and M. Wegner, German Pat., 1999, DE 53. M. N. He, L. B. Hu, Z. Xue, C. C. Su, P. Redfern, L. A. Curtiss, B.
19829030.
Polzin, A. von Cresce, R. Xu and Z. C. Zhang, J Electrochem. Soc.,
2015, 162, A1725ꢀA1729.
18. W. Xu and C. A. Angell, Electrochem. Solid State Lett., 2001, 4, E1ꢀE4.
19. V. Aravindan, J. Gnanaraj, S. Madhavi and H.ꢀK. Liu, Chem. Eur. J., 54. Y. C. Li, S. Wan, G. M. Veith, R. R. Unocic, M. P. Paranthaman, S. Dai
2011, 17, 14326ꢀ14346.
20. X. R. Zhang, N. Sukpirom and M. M. Lerner, Materials Research
Bulletin, 1999, 34, 363ꢀ372.
21. S. Y. Li, W. Zhao, X. L. Cui, H. M. Zhang, X. X. Wang, W. X. Zhong,
H. X. Feng and H. N. Liu, Electrochimica Acta, 2014, 129, 327ꢀ333.
22. K. Xu, U. Lee, S. S. Zhang, M. Wood and T. R. Jow, J. Electrochem.
Soc., 2004, 151, A2106ꢀA2112.
23. K. Xu, U. Lee, S. S. Zhang, M. Wood and T. R. Jow, Electrochem. Solid
State Lett., 2004, 7, A273ꢀA277.
and X. G. Sun, Adv. Energy Mater.
10.1002/aenm.201601397.
55. M. Q. Xu, N. Tsiouvaras, A. Garsuch, H. A. Gasteiger and B. L. Lucht, J
Phys. Chem. C, 2014, 118, 7363ꢀ7368.
56. N. P. W. Pieczonka, L. Yang, M. P. Balogh, B. R. Powell, K.
Chemelewski, A. Manthiram, S. A. Krachkovskiy, G. R. Goward, M. H.
Liu and J. H. Kim, Journal of Physical Chemistry C, 2013, 117, 22603ꢀ
22612.
57. S. S. Zhang, K. Xu and T. R. Jow, J Power Sources, 2003, 115, 137ꢀ140.
58. N. Takami, A. Satoh, M. Hara and T. Ohsaki, J. Electrochem. Soc., 1995,
142, 371ꢀ379.
,
2016, DOI:
24. S. S. Zhang, Electrochem. Commun., 2006, 8, 1423ꢀ1428.
25. M. Q. Xu, L. Zhou, L. S. Hao, L. D. Xing, W. S. Li and B. L. Lucht, J. of
Power Sources, 2011, 196, 6794ꢀ6801.
59. X. G. Sun, C. Liao, N. Shao, B. K. Guo, J. R. Bell, H. M. Luo, D. E.
Jiang and S. Dai, J. Power Sources, 2013, 237, 5ꢀ12.
26. T. Schedlbauer, S. Krueger, R. Schmitz, R. W. Schmitz, C. Schreiner, H.
J. Gores, S. Passerini and M. Winter, Electrochimica Acta, 2013, 92, 60. C. Liao, N. Shao, K. S. Han, X. G. Sun, D. E. Jiang, E. W. Hagaman and
102ꢀ107.
S. Dai, Phys. Chem. Chem. Phys., 2011, 13, 21503ꢀ21510.
27. J. Liu, Z. Chen, S. Busking, I. Belharouak and K. Amine, J Power
Sources, 2007, 174, 852ꢀ855.
28. S. Zugmann, M. Fleischmann, M. Amereller, R. M. Gschwind, H. D.
Wiemhoefer and H. J. Gores, Electrochimica Acta, 2011, 56, 3926ꢀ3933.
29. S. Zugmann, D. Moosbauer, M. Amereller, C. Schreiner, F. Wudy, R.
Schmitz, R. Schmitz, P. Isken, C. Dippel, R. Mueller, M. Kunze, A. Lexꢀ
Balducci, M. Winter and H. J. Gores, J Power Sources, 2011, 196, 1417ꢀ
1424.
30. X. G. Sun, J. B. Kerr, C. L. Reeder, G. Liu and Y. B. Han,
Macromolecules, 2004, 37, 5133ꢀ5135.
31. X. G. Sun, C. L. Reeder and J. B. Kerr, Macromolecules, 2004, 37, 2219ꢀ
2227.
32. X. G. Sun and J. B. Kerr, Macromolecules, 2006, 39, 362ꢀ372.
33. C. Schreiner, M. Amereller and H. J. Gores, Chem. Eur. J., 2009, 15,
2270ꢀ2272.
34. P. F. Driscoll, L. Yang, M. Gervais and J. B. Kerr, ECS Transactions,
2011, 33, 33ꢀ53.
35. L. Yang, H. J. Zhang, P. F. Driscoll, B. Lucht and J. B. Kerr, ECS
Transactions, 2011, 33, 57ꢀ69.
36. X. G. Sun, G. Liu, J. B. Xie, Y. B. Han and J. B. Kerr, Solid State Ionics,
2004, 175, 713.
37. C. Liao, K. S. Han, L. Baggetto, D. A. Hillesheim, R. Custelcean, E. S.
Lee, B. K. Guo, Z. H. Bi, D. E. Jiang, G. M. Veith, E. W. Hagaman, G.
M. Brown, C. Bridges, M. P. Paranthaman, A. Manthiram, S. Dai and X.
G. Sun, Adv. Energy Mater., 2014, 4, 1301368 (1301361ꢀ1301312).
38. X. G. Sun, C. Liao, L. Baggetto, B. K. Guo, R. R. Unocic, G. M. Veith
and S. Dai, J. Mater. Chem. A, 2014, 2, 7606ꢀ7614.
8 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012