Synthesis of aminoalkylsilanes with oligo(ethylene oxide) unit as multifunctional electrolyte additives for lithium-ion batteries

Article abstract of DOI:10.1007/s11426-013-4861-5

Aminoalkylsilanes with oligo(ethylene oxide) units were designed and synthesized as multifunctional electrolyte additives for lithium-ion batteries. The chemical structures were fully characterized by nuclear magnetic resonance (NMR) spectroscopy and thei

Full text of DOI:10.1007/s11426-013-4861-5

SCIENCE CHINA
Chemistry
June 2013 Vol.56 No.6: 739–745
doi: 10.1007/s11426-013-4861-5
• ARTICLES •
Synthesis of aminoalkylsilanes with oligo(ethylene oxide) unit as
multifunctional electrolyte additives for lithium-ion batteries
WANG JingLun, LUO Hao, MAI YongJin, ZHAO XinYue & ZHANG LingZhi*
Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China
Received October 29, 2012; accepted January 14, 2013; published online April 11, 2013
Aminoalkylsilanes with oligo(ethylene oxide) units were designed and synthesized as multifunctional electrolyte additives for
lithium-ion batteries. The chemical structures were fully characterized by nuclear magnetic resonance (NMR) spectroscopy
and their thermal properties, viscosities, electrochemical windows, and ionic conductivities were systematically measured.
With adding one of these compounds (1 vol. %, DSC3N1) in the baseline electrolyte 1.0 M LiPF6 in EC: DEC (1:1, in volume),
Li/LiCoO2 half cell tests showed an improved cyclability after 100 cycles and improved rate capability at 5C rate condition.
Electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and energy dispersive spectroscopic
(EDS) analysis confirmed the acid scavenging function and film forming capability of DSC3N1. These results demonstrated
that the multifunctional organosilicon compounds have considerable potential as additives for use in lithium-ion batteries.
aminoalkylsilane, electrolyte additives, lithium cobalt oxide, lithium-ion batteries
oligo(ethylene oxide) substituents as electrolyte solvents for
1 Introduction
LIBs [9]. On the other hand, it has also been reported that
the electrochemical performances of LIBs could be im-
proved remarkably by adding a small amount of organosili-
con additives in the conventional alkylcarbonate based elec-
trolytes [10]. Takechi and Shiga disclosed a series of
“SiN” based additives, such as N,N-diethylamino-trime-
thylsilane, as both H2O and HF scavenger via breaking the
active SiN bond [11]. Zhang reported that the flammability
of the alkylcarbonate electrolytes was effectively sup-
pressed with adding 10 vol% vinyl-tri-(methoxydiethoxy)
silane [12]; Walkowiak et al. declared that the polyeth-
er-functionalized disiloxanes could be used as a film form-
ing additive to prevent graphite exfoliation in propylene
carbonate based electrolytes [13].
In this paper, we report a novel series of aminoal-
kylsilane compounds with oligo(ethylene oxide) units as
multifunctional electrolyte additives for LIBs. These com-
pounds are designed based on the oligo(ethylene oxide)
chain end-capped with organosilicon functional group and
alkylamine group on each end. The oligo(ethylene oxide)
Recently, much effort has been devoted to developing ad-
vanced electrolyte materials to satisfy the ever-increasing
applications of lithium-ion batteries (LIBs) demanding high
energy density and safety [1]. The development of func-
tional electrolyte additives is recognized as one of the most
economic and effective methods to improve the perfor-
mance of LIBs [2]. Various kinds of additives have been
reported so far, including film forming additives [3], flame
retardant additives [4], high/low temperature additives [5],
over charge additives [6], and high voltage additives [7].
Organosilicon compounds have received much attention
as electrolytes for energy storage devices due to their ther-
mal and electrochemical stability, less flammable and envi-
ronmentally benign characteristics [8]. West and Amine et
al. systematically studied the synthesis and electrochemical
properties of organosilicon compounds functionalized with
*Corresponding author (email: lzzhang@ms.giec.ac.cn)
© Science China Press and Springer-Verlag Berlin Heidelberg 2013
chem.scichina.com www.springerlink.com

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Wang JL, et al. Sci China Chem June (2013) Vol.56 No.6
chain provides the ability to complex lithium ions to ensure
the solvation of lithium salts; and the alkylamine group acts
as an acid scavenger (HF generated from the decomposition
reaction of electrolytic salt) so as to improve the cycleabil-
ity of the cells [14]. The organosilicon groups, such as tri-
methylsilyl, disiloxanyl, and triethyloxysilyl group, may
introduce specific properties to the designed compounds
like flame retardant property, passive film forming capabil-
ity on the electrodes [1013].
was used to inspect the surface element composition of the
electrodes.
2.2 Synthesis of the aminoalkylsilanes
The synthesis of aminoalkylsilane, TMSCmNn (m=1, 3;
n=13), is shown in Scheme 1. TMSCmNn (m=1, 3; n=1, 2)
was synthesized by a nucleophilic substitution reaction of
ethanolamine sodium salt with the corresponding
chlorosilane. TMSCmNn (m=1; n=3) as an exception ex-
ample was synthesized in a four-step procedure outlined in
2 Experimental
route
B due to the commercial unavailability of
2-(2-(2-(dimethyl amino)-ethoxy)ethoxy) ethanol. DSC3Nn
(n=1, 2) and TESC3N2 were prepared by an H2PtCl6 cata-
lyzed hydrosilylation reaction of allyloxyethoxy substituted
dialkylamine with pentamethyldisiloxane and triethox-
ysilane respectively (route C). All products were purified by
repeated distillation and monitored by gas chromatography
to ensure 99% purity; their chemical structures were con-
firmed by NMR.
2.1 Materials and measurements
Allylbromide, N,N-dimethyl ethanolamine, 2-[2-(dimethyl
amino)ethoxy]ethanol, and organosilicon raw materials for
the synthesis of electrolyte additives are commercially
available and used without further purification. Battery
grade materials were used as received: LiPF6, dimethyl
carbonate (DEC), and ethylene carbonate (EC) (H2O<20
ppm, Zhangjiagang Guotai-Huarong, China); LiCoO2 (Hu-
nan Reshine New Material Co.); Li foil (China Energy
Lithium); aluminum foil (99.99% purity, 0.5 mm thick,
Shenzhen Weifeng DianZi), separator (Celgard 2325).
Typical procedures for the synthesis of DSC3N1: to a
two-necked 250 mL flask, 2-(allyloxy)-N,N- dimethyleth-
anamine (10.6 g, 82 mmol), pentamethyldisiloxane (13.9 g,
94 mmol), and H2PtCl6 (catalytic amount 0.4% mmol) were
added, and the reaction mixtures were stirred at 90 °C until
the completion of the reaction. After that, the product was
purified by distillation giving colorless liquid with the yield
1H NMR, 13C NMR and 29Si NMR were taken on a
Bruker avence 600 spectrophotometer or on a Varian
Mercury Vx300. The water contents of the synthesized
organosilicon compounds were less than 30 ppm, which
were measured by Karl-Fisher coulometric moisture titrator
(831 KF). Viscosity () measurements were performed on a
multi-speed digital viscometer (Shanghai Nirun Intelligent
Technology Co., SNB-2). The dielectric constants () were
measured on an 870 Liquid Dielectric Constant Meter
(Scientifica). DSC data were obtained using a NETZSCH
DSC204C instrument, calibrated with indium and
polydimethylsiloxane. All samples were cooled with liquid
nitrogen down to –150 °C, followed by heating from
150 °C to 60 °C at a rate of 10 °C/min. The glass transition
temperature (Tg) value was determined from the onset of the
glass transition of the second heat run. Ionic conductivities
were determined by DDS-310 conductivity instrument,
variable temperature conductivity measurements were
conducted in a water bath for temperature ranging between
0 °C and 80 °C. EIS results were obtained with a Zenni-
um/IM6 electrochemical workstation (Zahner, Germany)
with 5 mV AC amplitude in the frequency range of 0.01 Hz
to 100 kHz. X-ray photoelectron spectroscopy (XPS) tests
of LiCoO2 electrodes were performed with ESCALAB 250
(Thermo Fisher Scientific, USA) at 2×10–9 mbar. Al
K(1486.6 ev) was used as the X-ray source at 15 Kev of
anode voltage. Before XPS test, the cycled LiCoO2 elec-
trode was washed three times with pure DEC followed by
vacuum drying overnight at room temperature. Energy dis-
persive spectroscopy (EDS) (FE SEM Hitachi S-4800 Japan)
1
of 85%, b.p.: 47 °C/0.7 mmHg; H NMR (600 MHz,
CDCl3): 3.49~3.52 (t, 2H, OCH2CH2N), 3.36~3.40 (t, 2H,
CH2OCH2CH2N), 2.47~2.50 (t, 2H, CH2N), 2.26 (s, 6H,
–N(CH3)2), 1.57~1.61 (m, 2H, CH2CH2Si), 0.46~0.50 (m,
2H, –CH2CH2Si), 0.02~0.05 (d, 15H, –Si(CH3)2OSi(CH3)3);
13C NMR (150.9 MHz, CDCl3): 74.08, 58.92, 45.85, 23.38,
14.26, 1.92, 0.22; 29Si NMR (59.6 MHz, CDCl3): 8.94, 9.16.
DSC3N2 and TESC3N2 were synthesized with the similar
procedure of DSC3N1.
1
DSC3N2: yield: 74%; b.p.: 98 °C/0.2 mmHg; H NMR
(600 MHz, CDCl3): 3.56~3.61 (m, 6H, OCH2CH2OCH2),
3.39~3.42 (t, 2H, OCH2CH2CH2Si), 2.49~2.51 (t, 2H,
CH2N), 2.25 (s, 6H, N(CH3)2), 1.57~1.60 (m, 2H,
CH2CH2Si), 0.46~0.49(m, 2H, CH2Si), 0.02~0.04 (d, 15H,
Si(CH3)3). 13C NMR (150.9 MHz, CDCl3): 74.22, 70.40,
70.02, 69.35, 58.82, 45.85, 23.38, 14.19, 1.93, 0.23. 29Si
NMR (59.6 MHz, CDCl3): 8.82, 9.04.
1
TESC3N2: yield: 74%; b.p.: 97–98 °C/0.2 mmHg; H
NMR (600 MHz, CDCl3): 3.77~3.78 (m, 6H,
(CH3CH2O)3Si), 3.54~3.57 (m, 6H, OCH2CH2OCH2), 3.40
(m, 2H, SiCH2CH2CH2O), 2.47 (m, 2H, OCH2CH2N), 2.23
(s, 6H, N(CH3)2) , 1.66 (m, 2H, SiCH2CH2CH2) , 1.17 (m,
9H, Si(OCH2CH3)3) , 0.59 (m, 2H, SiCH2CH2CH2). 13C
NMR (150.9 MHz, CDCl3): 73.62, 70.39, 69.99, 69.35,
58.82, 58.35, 45.84, 22.92, 18.25, 6.42. 29Si NMR (59.6
MHz, CDCl3): –43.24.
Typical procedures for the synthesis of TMSC1N1: to a

Wang JL, et al. Sci China Chem June (2013) Vol.56 No.6
741
Scheme 1 Synthetic routes of multifunctional aminoalkylsilanes.
two-necked 250 mL flask, N,N-dimethylethanolamine (38 g,
0.42 mol) and sodium (3.6 g, 0.16 mol) were added, and the
reaction mixtures were heated until the sodium disappeared
completely. After cooling to room temperature, (chlorome-
thyl)trimethylsilane (20.0g, 0.16 mol) was added dropwise,
and then the reaction mixtures were stirred vigorously for
48 h at 110 °C. After completion of the reaction, the product
was extracted with hexane and separated by distillation
elaborately. TMSC1N1: yield: 66%, b.p.: 160 °C. 1H
NMR(600MHz, CDCl3): –0.01 (s, 9H, Si(CH3)3), 2.22 (s,
6H, N(CH3)2), 2.38 (t, J=6.0 Hz, 2H, NCH2), 3.07 (s, 2H,
SiCH2O), 3.45 (t, J= 6.0 Hz, 2H, OCH2CH2OCH2); 13C
NMR (150.9 MHz, CDCl3): 0.00, 49.17, 61.72, 68.30, 77.16;
29Si NMR (119.3 MHz, CDCl3): –2.62. TMSC1N2,
TMSC3N1, and TMSC3N2 were synthesized with the sim-
ilar procedure of TMSC1N1.
2.3 Cells preparation
Working electrodes were prepared by mixing LiCoO2, car-
bon black and polyvinylidene fluoride (PVDF) at a weight
ratio of 80:10:10 in N-Methyl-2-pyrrolidone (NMP), and
then the slurry was spread onto an Al foil and dried at 80 °C
under vacuum for 6 h. The lithium metal (99.9%) was used
as the counter electrode. All the cells were assembled under
a dry argon atmosphere in the glove box (Mikrouna, H2O
and O2 <1 ppm). The constant current discharge and charge
measurements were carried out with a multi-channel battery
test system (NEWARE BTS-610) using coin-type cells
(CR2025) at room temperature.
3 Results and discussion
1
TMSC1N2: yield: 67%; b.p.: 34–35 °C/0.2 mmHg; H
3.1 Basic physical and electrochemical properties
NMR(600 MHz, CDCl3): = 0.01 (s, 9H, Si(CH3)3), 2.24 (s,
6H, N(CH3)2), 2.47 (t, J=5.8, 2H, NCH2), 3.12 (s, 2H,
SiCH2O), 3.55 (m, 6H, OCH2CH2OCH2). 13C NMR (150.9
MHz, CDCl3): –2.91, 46.02, 59.10, 65.53, 69.59, 70.35,
74.92. 29Si NMR (119.3 MHz, CDCl3): –2.99.
Basic physical and electrochemical properties of the synthe-
sized compounds, such as viscosity (), dielectric constant
(), glass transition temperature (Tg), and ion conductivity
(), are summarized in Table 1. Both the dielectric constant
and ionic conductivity of these compounds increased with
increasing ethylene oxide (EO) chain length, even though
the viscosity correspondingly increased at the same time. In
addition, the ionic conductivities of these compounds with
the same amino ether chain structure were significantly af-
fected by the organosilicon group and methylene spacer
length. For instance, the conductivity of trimethyl com-
pounds decreased notably with increasing the carbon spacer
length, possibly due to the decreased viscosity. The ionic
1
TMSC3N1: yield: 67%; b.p.: 201–203 °C; H NMR(600
MHz, CDCl3): =–0.01 (s, 9H, Si(CH3)3), 0.47 (m, 2H,
(CH3)3SiCH2), 1.60 (m, 2H, (CH3)3SiCH2CH2), 2.28 (s, 6H,
N(CH3)2), 2.51 (t, J=5.7 Hz , 2H, CH2N(CH3)2), 3.47 (t,
J=7.2Hz, 2H, (CH3)3SiCH2CH2CH2), 3.60 (t, J=5.7 Hz,
CH2CH2N(CH3)2); 13C NMR (150.9 MHz, CDCl3): –0.00,
14.28, 25.77, 47.68, 60.75, 70.59, 75.99; 29Si NMR (119.3
MHz, CDCl3): 0.52.
TMSC3N2: yield: 72%; b.p.: 53 °C/0.2 mmHg; 1H
NMR(600 MHz, CDCl3): = –0.02 (s, 9H, Si(CH3)3), 0.47
(m, 2H, (CH3)3SiCH2), 1.58 (m, 2H, (CH3)3SiCH2CH2),
2.27 (s, 6H, N(CH3)2), 2.52 (t, J=6.0, 2H, CH2N(CH3)2),
3.42 (t, J=7.2, 2H, (CH3)3Si CH2CH2CH2), 3.61 (m, 6H,
TMSC3OCH2CH2OCH2); 13C NMR (150.9 MHz, CDCl3):
0.03, 14.24, 25.73, 47.70, 60.59, 71.18, 71.78, 72.18, 76.07;
29Si NMR (119.3 MHz, CDCl3): 0.49.
Table 1 Physical data, conductivity for the aminoalkylsilanes
 (cP) [a]
1.29
 [a]
 (mS/cm)[a]
0.50
Compound
TMSC1N1
TMSC1N2
TMSC1N3
TMSC3N1
TMSC3N2
DSC3N1
Tg (℃)
138
119
106
127
116
122
112
114
2.85
3.39
5.40
3.31
3.80
2.86
3.21
4.35
2.30
0.77
2.98
0.81
1.72
0.44
TMSC1N3 was synthesized as Scheme 1B: yield: 76%;
1
2.70
0.60
b.p.: 90 °C/0.5 mmHg; H NMR(600 MHz, CDCl3): =0.10
2.04
0.33
(s, 6H, Si(CH3)2), 2.22 (s, 12H, NCH3), 2.45 (t, 4H, J=
5.8Hz, NCH2CH2), 3.523 (m, 8H, SiO(CH2CH2O)2), 3.79 (t,
4H, J=5.4Hz, NCH2). 13C NMR (150.9 MHz, CDCl3): –0.00,
48.99, 61.98, 68.85, 72.56, 75.29. 29Si NMR (119.3 MHz,
CDCl3): –1.75.
DSC3N2
3.28
0.34
TESC3N2
3.52
0.70
a) Data were corrected at 25 °C, and the conductivity was measured
with doping 1M LiTFSI.

742
Wang JL, et al. Sci China Chem June (2013) Vol.56 No.6
conductivity of these aminoalkylsilanes ranges between
0.33 and 0.81 mS/cm at room temperature. Among them,
TMSC1N3 with one methylene spacer and three EO units
showed the highest ionic conductivity. The Arrhenius plots
of the ionic conductivity of the electrolytes were slightly
curved (Figure 1(a)), suggesting that the motion of EO
chains plays a role in the ionic conductivity of the electro-
lytes [9(a)]. The differential scanning calorimetry (DSC)
curves of these compounds are depicted in Figure 1(b),
showing that Tg increased with increasing the chain length
of EO units and methylene spacer, and only one se-
cond-order phase inflection for Tg at low temperature
(–100 °C). Therefore, the aminoalkylsilanes are suitable
for low temperature applications because these compounds
are in a completely amorphous state within the low temper-
ature range studied [9(b)].
(1:1, in volume) as electrolyte with/without 1 vol%
DSC3N1 additive, which is an optimized addition volume
through parallel experiments. The cell was charged and
discharged at the rate of 0.2 C with the cut-off voltage of
3.0–4.2 V/vs Li/Li+. The discharge capacity of LiCoO2/Li
cell at the 1st and the 100th circle with DSC3N1 addition
(compared with that of the base electrolyte) is 135 mAh/g
(136 mAh/g) and 113 mAh/g (104 mAh/g), respectively.
The LiCoO2/Li cell with 1 vol% DSC3N1 additive showed
better capacity retention (89%) than that of the base elec-
trolyte cell (80%) after 100 cycles, indicating that the cyclic
performance of LiCoO2/Li cell is improved significantly in
the electrolyte containing DSC3N1 additive. It has been
generally recognized that the acidic impurities in electro-
lytes originate from two factors: (1) the existence of low
content of water and acidic impurities in electrolyte before
use, and (2) chemical oxidation of the electrolyte solvents
by oxygen released from cathode during occasional over-
charging [17]. This improved cycling capability could be
attributed to the alkylamine group of DSC3N1 which pre-
vented deteriorating the performance of LiCoO2 by acidic
impurities in the electrolyte [2, 14]. The LiCoO2/Li cell with
DSC3N1 addition also exhibited improved C-rate perfor-
mance (Figure 2(b)), retaining 86%/65% capacity retention
as compared with 65%/1% for the cell without DSC3N1
additive at 1C/5C rate, respectively. When further cycled at
3.2 Cell tests
Thanks to the acid scavenger function of amino group and
interfacial film forming property of disiloxanyl group on
LiCoO2 electrode [15], we picked DSC3N1 to investigate
its effect on the cell performance of LiCoO2 cathode, a most
commonly used cathode material in LIBs [16]. Figure 2(a)
shows the specific charge/discharge capacities versus cycle
number for LiCoO2/Li cell using 1.0 M LiPF6 in EC: DEC
Figure 1 (a) Arrhenius plots of the ionic conductivity of the aminoalkyl silanes with 1M LiTFSI salt; (b) DSC traces of the aminoalkylsilanes.
Figure 2 Cycling performances (a) and C-rate performances (b) of LiCoO2/Li cell in different electrolytes.

Wang JL, et al. Sci China Chem June (2013) Vol.56 No.6
743
Table 2 Typical fitting parameters for the Nyquist plots in Figure 3
0.2C after 5C test, both of the cells with/without DSC3N1
recovered the capacity to the former 0.2C level, indicating
that DSC3N1 had a positive function on improving the
C-rate performance of LiCoO2/Li cells. The rate capability
of the cells depends on the reaction kinetics of electron
transfer and Li+ ion transfer to a large extent. Extensive
studies have been devoted to improving the electron transfer
rate of LiCoO2 cathode by modifying its particle size, mor-
phology, porosity, and elemental composition [18]. As far
as we know, DSC3N1 is one of a few compounds reported
so far which improved the rate performance of LiCoO2
cathode when used as an additive in the electrolytes [19].
LiCoO2 samples
Rf1 ()
7.83
Rf2 ()
7.99
Rct ()
13.33
4.23
Without DSC3N1 additive
With DSC3N1 additive
9.36
2.70
3.4 Surface analysis
The X-ray photoelectron spectroscopy (XPS) of LiCoO2
electrodes cycled with or without DSC3N1 addition in the
electrolyte was conducted to analyze their surface compo-
nents. Comparing the F1s spectrum of LiCoO2 electrodes
cycled with (Figure 4(a)) and without DSC3N1 addition
(Figure 4(b)), we found that the relative content of LiF (ac-
cording to the integration of LiF peak using PVDF as refer-
ence) decreased significantly in the case with DSC3N1 ad-
dition. We presume this to the HF acid scavenging function
of DSC3N1 containing amine group as shown in reaction
(3), which reduced the LiF deposition by suppressing the
reaction of LiCoO2 with HF shown in reaction (2) [21].
Accordingly, Rf and Rct were decreased due to less deposi-
tion of high resistance LiF on the surface of LiCoO2, as seen
in Table 2.
3.3 Electrochemical impedance spectroscopy analysis
The electrochemical impedance spectroscopy (EIS) meas-
urements of the cells with/without DSC3N1 additive after
20 cycles and charged to 4.2 V are provided in Figure 3. All
the Nyquist plots are composed of two partially overlapping
semi-circles at high and medium frequency range and a
straight sloping line at the low frequency end, representing
respectively three resistance components: film resistance
(Rf), charge transfer resistance (Rct), and Li+ diffusion re-
sistance [20]. Nyquist plots were fitted with the equivalent
circuit shown in the inset of Figure 3. Re represents the
electrolyte resistance and Qd is the diffusion capacitance
attributed by the diffusion process of the Li+ in the pore
channel of the electrode materials. Rf1 and Rf2 correspond to
the multilayer surface film resistance and Rct is the charge
transfer resistance of Li+ at the interface between electrolyte
and electrode [19]. Typical parameters are summarized in
Table 2, revealing that the Rf (containing Rf1 and Rf2) and Rct
for the LiCoO2 without DSC3N1 additive are 15.8  and
13.3 ; whereas for the LiCoO2 with DSC3N1 additive,
they are drastically reduced to 12.1  and 4.3 , respec-
tively, suggesting the enhanced kinetics of Li+ transport and
hence improved C-rate performance with DSC3N1 additive.
2LiPF6+5H2O→2LiF+10HF+P2O5
4LiCoO2+4HF→CoO2+Co3O4+4LiF+2H2O
DSC3N1+HF→DSC3N1H+ F
(1)
(2)
(3)
On the other hand, Si2p spectrum revealed that
Si-containing species (Si–C, Si–O) were observed on the
surface films of LiCoO2 electrode cycled with the addition
of DSC3N1 (Figure 4(c)). Energy dispersive spectroscopy
(EDS) analysis also confirmed a silicon signal with an ele-
ment weight of 0.20% at 1.8 keV related to C, O, F, and P
atoms on LiCoO2 electrode of the cell with DSC3N1 addi-
tive after 30 cycles (Figure 4(d)). Based on these data, we
can conclude that disiloxanyl group in DSC3N1 was appar-
ently involved in the formation of passive film on the sur-
face of LiCoO2 electrode. Similar to the report of disiloxa-
nyl compound participating in passive film formation on the
surface of LiCoO2 [15], the passive film formation property
of DSC3N1 is likely to suppress the LiF formation on
LiCoO2 electrode thus reduced the impedance of LiCoO2
electrode and improved the C-rate performance of
LiCoO2/Li cell shown in Figure 2(b).
4 Conclusions
In conclusion, we reported a new series of aminoalkylsilane
compounds with oligo(ethylene oxide) units as multifunc-
tional electrolyte additives for LIBs. These compounds have
low viscosities, high conductivities, and very low glass
transition temperatures. The LiCoO2/Li cell exhibited im-
proved cyclability and rate performance with adding 1 vol%
Figure 3 Nyquist plots of LiCoO2 electrodes with (a) or without (b)
DSC3N1 additive. The spots (○) correspond to the experimental data, the
solid lines stand for the calculated data from the equivalent circuits (inset).

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Wang JL, et al. Sci China Chem June (2013) Vol.56 No.6
Figure 4
XPS spectrum of F1s detected on the LiCoO2 electrode cycled (a) with/(b) without DSC3N1 addition; (c) XPS spectrum of Si2p detected on the
LiCoO2 electrode cycled with DSC3N1; (d) EDS of LiCoO2 electrode after 30 cycles for the cell with DSC3N1 addition.
6
Moshurchak LM, Buhrmester C, Wang RL, Dahn JR. Comparative
DSC3N1 in the base electrolyte. EIS, XPS, and EDS ex-
periments revealed that the interfacial impedance of the cell
and the relative content of LiF on the surface of LiCoO2
were decreased significantly with DSC3N1 additive in the
base electrolyte, due to the acid scavenging and passive film
forming function of DSC3N1. These results demonstrate
that these aminoalkylsilanes have considerable potential as
electrolyte additives for use in lithium-ion batteries.
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