Abstract

A new system LixCoO2 (0<x⩽1) has been prepared by electrochemical extraction of lithium from the parent LiCoO2 ordered-rocksalt structure. Measured open-circuit voltages with respect to lithium metal are approximately twice those of LixTiS2 (0⩽x⩽1), and a theoretical energy density of 1.1 kW h kg−1 is calculated for LixCoO2/Li. Preliminary voltage-composition curves show low over-voltages and good reversibility for current densities up to 1 mA cm−2 over a large range of x.