Influence on the first charge capacity of layered Li-Mn-O-based electrodes by combining stoichiometric and nonstoichiometric materials

By forming electrodes consisting of a (1:1) mixture of stoichiometric to nonstoichiometric layered lithium manganese oxides with the O3 structure, illustrated specifically by combining LiMnO2 and Li0.57Mn0.88Li0.025Co0.023O2, it is possible to obtain a 4% higher charge than discharge capacity on the first cycle, at a rate of C/8 and voltage limits of 2.4-4.6 V. A (2:1) mixture (stoichiometric:nonstoichiometric) exhibits an excess capacity on the first charge of 24% under the same conditions. Both ratios show very similar charge/discharge profiles on subsequent cycles. The fade rates at higher cycle number are greater than for the nonstoichiometric material alone. The approach, of combining stoichiometric and nonstoichiometric layered lithium managaese oxides with the O3 structure, can be extended to any of the wide range of nonstoichiometric LixMnyO2 compounds, whether or not doped with a range of other ions. (C) 2004 The Electrochemical Society.