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The lithium/sulfur cell is very attractive because of its high theoretical specific capacity and low production cost. The sulfur electrode is prepared from sulfur, with carbon as an electronic conductor and PEO as an ionic conductor. We changed the carbon content of a 50 wt.% sulfur electrode from 10 wt.% to 40 wt.%. The lithium/PEO/sulfur cell showed two plateau potential regions (2.4 V, 2.1 V) and high discharge capacity, i.e., 1484 mAh/g (88 % utilization) for optimum composition. The discharge capacity decreased drastically by charge-discharge cycling. The degradation rate as well as the first discharge capacity depended on the composition of the sulfur electrode. The optimum composition of the 50 wt.% sulfur electrode was 30 wt.% carbon and 20 % PEO.

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Abstract. Despite the reported enhanced electrochemical behavior of graphite anodes due to the addition ofNaC104 salts in to the electrolytes used in lithium battery applications, a detailed investigation upon the effect of addition of NaPF0 salt in an electrolyte containing 1 M LiPF6 in 1:1 V/V EC:DEC has resulted in inferior electrochemical behavior of graphite, i.e., quite contrast to the reported behavior of improved effects of addition of NaCIO4 into 1 M LiC104 solution, the addition of 0.22 tool dm -3 NaPF 6 salt has been found to reduce the capacities of lithium-ion cells containing 1 M LiPF 6 in 1:1 V/V EC:DEC. Towards this study, cells fabricated with and without the addition of 0.22 mol dm -3 NaPF 6 in 1 M LiPF 6 (1:1 V/V EC:DEC) were subjected to a systematic charging at a constant C/10 rate and discharging of cells at four different rates, viz., C/5, C/2 and C rates at the end of every 5 cycles. The observed results of the charge-discharge studies up to 15 cycles are discussed in this preliminary communication.