Page 19 - Shimadzu Journal vol.10 Issue1

Materials Science

Note that since thermal conductivity
is different between argon and air, the
heat exhaust mechanism of the instru-
ment may not function properly, thereby
preventing acquisition of correct infrared
spectra. To avoid this, we used a cooler to
enhance heat exhaustion in this analysis,
and controlled the dew point in the glove
box to -70 ˚C (moisture content of 2.58
ppm) or lower, and the oxygen concen-
tration to 0.3 ppm or lower. Analysis in
a glove box thus enables highly accurate
measurements without being affected by Fig. 2 Example of IRSpirit Glove Fig. 3 IRSpirit (Left) and Wireless Converter (Right) in Glove Box
water vapor or oxygen. Box System

Effect of Atmospheric Gases on
Measurement of Electrolyte Solutions for
Lithium-Ion Secondary Batteries
Argon atmosphere
An electrolyte of EC (ethylene carbonate) + DEC (diethyl car-
bonate) (3 : 7) solution containing 1M LiPF (lithium hexafluoro-
6
phosphate), an organic electrolyte solution commonly used in
lithium-ion secondary batteries, was measured under air and argon
atmospheres. Fig. 4 shows the measured infrared spectra and Fig. 5 Air atmosphere
shows the enlarged region between 2800 and 4000 cm in Fig. 4.
-1
Although the optical properties of argon and air are very dif-
ferent, Fig. 4 shows that the infrared spectra acquired under both Fig. 4 Infrared Spectra of EC+DEC (3 : 7) Electrolyte Solution Containing
1M LiPF
atmospheres were almost identical, appearing to be unaffected by 6
the difference of atmosphere.
Note that in Fig. 5, the broad absorption of symmetric and an-
tisymmetric OH-stretching vibrations from water molecules were
observed between 3400 and 3700 cm under the air atmosphere. Argon atmosphere
-1
Meanwhile, the influence was negligible in the infrared spectrum
under the argon atmosphere.
Symmetric OH-stretching
vibration
Antisymmetric OH-stretching
vibration Air atmosphere
Measurement of Electrolyte Solution
for Lithium-Ion Secondary Battery Fig. 5 Infrared Spectra of EC+DEC (3 : 7) Electrolyte Solution Containing
in Inert Atmosphere 1M LiPF (Enlarged)
6
Organic electrolyte solutions are used as the electrolyte solution
for lithium-ion secondary batteries, and their moisture content
is strictly controlled. Such an electrolyte solution was measured
by FTIR in an argon atmosphere.
Fig. 6 shows the infrared spectra of EC+DEC (3 : 7) electrolyte
solution with 1M LiPF and EC+DEC (3 : 7) solution without 1M
6
LiPF . The only difference between the two samples is the presence
6
or absence of LiPF .
6
* In this application, measurements were performed under specific conditions
and environments since glove boxes and argon atmospheres reduce the heat
exhaust function and may prevent proper instrument operation. Please contact
for details. Fig. 6 Infrared Spectra of EC+DEC (3 : 7) Electrolyte Solution Containing
1M LiPF (red) and EC+DEC (3 : 7) Solution (black)
6

Shimadzu Journal vol.10 Issue1 18