A high-rate manganese oxide for rechargeable lithium battery applications

LixMnO2 made by ion exchange of glycine-nitrate combustion synthesis-proces sed (GNP) orthorhombic Na0.44MnO2 (GNP-LixMnO2) has been cycled in lithium/ liquid electrolyte cell configurations at room temperature and lithium/poly mer cell configurations at 85 degreesC over one hundred times without showi ng capacity fading or phase conversion to spinel. At 2.5 mA/cm(2) in liquid cells (5C rate) or 1 mA/cm(2) (1.5C rate) in polymer cells, 80-95% of the expected capacity is delivered. The remarkable stability is attributable to the unusual double tunnel structure, which cannot easily undergo rearrange ment to spinel. The enhanced rats capability of GNP-LixMnO2 compared to con ventionally prepared materials is attributable to the shorter particle leng th, which allows faster diffusion of lithium ions along the tunnels. (C) 20 01 The Electrochemical Society. All rights reserved.