Synthesis of layered LiMnO₂ as an electrode for rechargeable lithium batteries

Abstract

RECHARGEABLE lithium batteries can store more than twice as much energy per unit weight and volume as other rechargeable batteries^1,2. They contain lithium ions in an electrolyte, which shuttle back and forth between, and are intercalated by, the electrode materials. The first commercially successful rechargeable lithium battery³, introduced by the Sony Corporation in 1990, consists of a carbon-based negative electrode, layered LiCoO₂ as the positive electrode, and a non-aqueous liquid electrolyte. The high cost and toxicity of cobalt compounds, however, has prompted a search for alternative materials that intercalate lithium ions. One such is LiMn₂O₄, which has been much studied as a positive electrode material^4–7; the cost of manganese is less than 1% of that of cobalt, and it is less toxic. Here we report the synthesis and electrochemical performance of a new material, layered LiMnO₂, which is structurally analogous to LiCoO₂. The charge capacity of LiMnO₂ (∼270mAhg^–1) compares well with that of both LiCoO₂ and LiMn₂O₄, and preliminary results indicate good stability over repeated charge–discharge cycles.