T. Sotomura et al., LITHIUM POLYMER SECONDARY CELL USING DISULFIDE-POLYANILINE COMPOSITE CATHODE AND GEL ELECTROLYTE, Denki Kagaku Oyobi Kogyo Butsuri Kagaku, 61(12), 1993, pp. 1366-1372
A lithium polymer secondary cell using an organodisulfide-polyaniline
composite cathode and a polyacrylonitrile gel electrolyte has been dev
eloped. The composite cathode was prepared as a mixture of 2,5-dimerca
pto-1,3,4-thiadiazole (organodisulfide) powders, polyaniline powders,
and the gel electrolyte. Organodisulfide and polyaniline were consider
ed to form an adduct providing a characteristic discharge curve monoto
nously decreasing from 4.0 to 2.5 V. To examine the charge-discharge c
ycle capability of the cell, the polarizability of the metallic lithiu
m and gel electrolyte interface was tested at first, and then the char
ge-discharge cycle performance of the cell using the composite cathode
with different composition was tested. The gel electrolyte containing
LiBF4 was found to afford a higher current output of over 1mA/cm(2) e
ven after cycling the voltage of a Li/gel electrolyte/Li cell 50 times
within +/- 0.5 V at 1 mV/s. As to the composition of the cathode, the
mole ratio of disulfide to polyaniline was found to be quite decisive
to obtain a higher charge-discharge cycle performance. Degradation in
discharge capacity was markedly reduced as the mole ratio of disulfid
e to polyaniline decreases below 1. The cell with a composite cathode
having an optimized composition provided a higher capacity of 80 mAh/g
-cathode even after 30 charge-discharge cycles.