Electrochemistry of sulphur adsorbed on carbon

Abstract

The modification of various carbonaceous materials by sulphur vapor was studied. The electrochemical properties of the products were measured in cells with a lithium counter electrode and either a liquid or a solid electrolyte. It was found that only physically adsorbed sulphur on the carbon surface is electrochemically active. Chemisorbed sulphur, which cannot be extracted with CS 2 or desorbed in vacuum at 300°C, is not electrochemically active. Sulphur is reduced in cells with a liquid electrolyte to polysulphides soluble in the electrolyte, causing irreversibility of the process. In cells with a solid polymeric electrolyte, P(EO) 8.LiClO 4, the sulphur-modified carbon can be cycled with a coulombic capacity decreasing from 175 mA h g −1 in the first to appreciably lower values in further cycles.