Studies on Improved Carbon Cathode Performance in High Rate <TEX>$Li/SOCl_2$</TEX> Cell

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J. Korean Ceram. Soc. > Volume 34(3); 1997 > Article

Journal of the Korean Ceramic Society 1997;34(3): 225.

고율 방전용 $Li/SOCl_2$ 전지의 카본 양극 개선에 관한 연구

최정자, 조성백, 박희숙

국방과학연구소

Studies on Improved Carbon Cathode Performance in High Rate $Li/SOCl_2$ Cell

ABSTRACT

The performance characteristics of high rate discharge LiSOCl2 cells are highly affected by carbon cathode. During the cell discharge, SOCl2 reduction takes place at the porous carbon cathode, resulting in the precipitation of reaction products, mainly LiCl, within the pores of the substrate. This leads to eventual passivation of the cathode surface and resulting cell failure. To improve the cathode performance, we ex-amined discharge reactions of cathodes (half-cell, 50 mA/$textrm{cm}^2$ constant current) with various surface density and thickness. The carbon cathode with the optimum capacity for our application is surface density 0.04 g/$textrm{cm}^2$ and thickness 1.4mm carbon. The carbon cathode with surface density 0.04g/$textrm{cm}^2$ and thickness 1.4 mm exhibits decreased polarization, increased discharge duration time and capacity (Ah/$textrm{cm}^2$) as compared with that with surface density 0.04g/$textrm{cm}^2$ and thickness 0.8mm. The porosities analyses on the two carbon cathodes show that total pore volume of the carbon cathode with thickness 1.4 mm is larger than that with thickness 0.8mm. The increased volume of mesopores (0.05$mu$m~0.5$mu$m) and macropores(>0.5$mu$m) is ob-served with the carbon cathode with thickness 1.4mm as compared with that with thickness 0.8mm, which can be related with the observed capacity increase. We observed LiCl crystals, cubic crystallites and fused, plate-like aggregates, and some elemental S as discharge products by EDS and XRD.

Key words: $Li/SOCl_2$ cell, Carbon cathode, Surface density, Thickness, Polarization, Pore volume