High temperature lithium/sulphur batteries: a preliminary investigation of a zeolite—sulphur cathode

A reversible lithium/sulphur high temperature cell is described in which the cathode consists of elemental sulphur absorbed in a zeolite 4A matrix. A lithium—aluminium alloy is used for the anode and the electrolyte is a molten ionic salt consisting of a LiI-KI eutectic (m.p. 260°). The cell was operated at 300° and underwent more than 70 continuous charge/discharge cycles (800 h) without significant loss in efficiency. The coulombic efficiency was more than 90% and the energy density 404 Wh/kg (based on the masses of active electrode materials, viz lithium metal and zeolite 4A—sulphur). The cell showed an open circuit voltage of 1.80 V, a short-circuit cd of about 1.1 A/cm2 and a maximum power of about 0.5 W/cm2. The internal resistance was 0.54 Ω (cathode surface area ∼ 3 cm2).