Abstract
prepared at 400°C with a structure that is intermediate between an ideal lithiated spinel and a layered structure has been investigated as an electrode in rechargeable lithium cells; it delivers a voltage vs. pure lithium that is significantly lower than the voltage provided by its high‐temperature analogue, 
, (synthesized at 900°C). The rechargeability of 
cells can be improved by leaching some lithium and a small amount of cobalt from 
by acid treatment and loading the cells in a charged state. The improvement in electrochemical performance is attributed to the formation of a defect spinel phase 
in which the lithium ions adopt the tetrahedral A sites and the cobalt and nickel ions the B sites of an 
spinel.