The Li/TiS2 cell with LiSCN electrolyte

Abstract

An ambient temperature, rechargeable lithium/titanium disulphide cell with a lithium thiocyanate-1,3dioxolane (DOL)-1,2-dimethoxyethane (DME) organic electrolyte was investigated. Electrolyte compositions of 2.5–3.5 molal LiSCN in solvent compositions from 100% DOL to 0.80∶0.20::DOL∶DME were tested. NMR, infrared spectroscopy and linear-sweep voltammetric studies indicated that the electrolyte was thermally and electrochemically stable, except for the slow formation of dioxolane oligomers. Test cells contained 10–30 mAh cm−2 of TiS2 with two- to sixfold excess of Li in parallel-plate, prismatic configuration. Performance delivered 80–90% of theoretical charge on first discharge and showed not only a rate-dependent cycle life, but also sensitivities to the (anode loading)/(cathode loading) ratio and cathode charge density. Cells with 10–15 mAh cm−2 of TiS2 and four to sixfold excess Li operated 35–50 cycles atC/5 toC/15 rates, while 30 mAh cm−2 cathodes with 3∶1 ∶∶anode: cathode ratio cycled 10–20 cycles atC/10. Results of half-cell studies, performance variation with temperature and overcharge and overdischarge behaviour of the cells are presented. Possible causes of the loss of efficiency during cycling are discussed.