Chemical Fluctuation in Olivine-type LiFe0.4Mn0.6PO4 Single Particle as Confirmed by Electron Energy-loss Spectroscopy Mapping (Supporting Information)

The olivine-type Li(Fe, Mn)PO4 positive electrode material is an alternative for LiFePO4 because of its higher energy density. In this study, chemical fluctuations in the Li(Fe, Mn)PO4 single particles were investigated using chemical mapping based on transmission electron microscopy. Spectral imaging based on electron energy-loss spectroscopy revealed the heterogeneous distribution of Mn and Fe in a single particle. The oxidation state of Fe fluctuated significantly in the elemental distribution compared with that of Mn, and Fe3+ was preferentially distributed in the Fe-rich domains of the particles. Natural air oxidation generates Fe3+ without batteries reactions. The spatial fluctuation of the Fe valence is affected by the local distribution of Mn and Fe.