Low temperature lithium/sulfur secondary battery. Semiannual progress report, December 1, 1974--June 1, 1975. [Development of dissolved sulfur cathode operable at ambient temperatures]

Abstract

The objective of this program is to develop a dissolved sulfur cathode which can be repeatably charged and discharged with minimal degradation and which is compatible with a Li anode. The redox behavior of dilute Sg, 0.1-1M L1C104 solutions in dimethyl sulfoxide (DMSO), dimethly formamide (DMF), tetrahydrofuran (THF), propylene carbonate (PC), y-butyrolactone (BL), sulfolane (SL), methyl acetate (MA) and pyridine was investigated using cyclic voltammetry. Ss and Sg~ reductions occur at more positive potentials and the redox reactions are more reversible in DMSO and DMF than in the other solvents. Raising the temperature generally enhances reversibility and reaction rates. Some evidence exists for the precipitation of Li2S x species on Au and Pt working electrodes (but not on C) leading to their passivation, especially at elevated temperatures .