Electronic structure and stability of the LixMn2O4 (0 < x < 2) system

LMTO-ASA self-consistent band structure calculations have been performed fo r the cubic spinel LiMn2O4 and its delithiated and lithiated phases: lambda -MnO2 and Li2Mn2O4. It has been shown that the Jahn-Teller distortion plays a vital role le in the stabilisation of the Li2Mn2O4 phase. The influence on the band structure of different possible positions for the lithium ions is investigated, and the phase transition from cubic to tetragonal symmetry for Li2Mn2O4 discussed. The change in potential associated with the insert ion of lithium ions into lambda-MnO2 to form LiMn2O4 and Li2Mn2O4 has been calculated as 1.51 V and 1.16 V, respectively. The lithium atoms are ionise d by contributing substantial character to the bonding band. However, the c harge transfer is small and the electron density around the lithium ions is higher than in lithium metal.