Correlating electronic structure with cycling performance of substituted LiMn2O4 electrode materials:: A study using the techniques of soft X-ray absorption and emission

Rechargeable batteries using LiMn2O4 cathodes are commercially attractive, if the problem of excessive capacity fading can be overcome. The cycling properties of these systems can be improved by partial metal substitution for the Mn. To understand the correlation between electrode performance and composition, Mn, Co, and Ni L-edge XAS and XES spectra of a series of LiMn2-yMeO4 samples (Me CO, Ni, Li) were recorded. Cobalt is shown to substitute into the spinel system as Co(III) and nickel as Ni(II). A positive correlation between the cycling stability of the electrode and. the covalency of the Mn is observed.