In situ XAFS study of the electrochemical deintercalation of Li from Li1−xMn2−yCryO4 (y = 1/9, 1/6, 1/3)

Chemical states and structural changes accompanying the electrochemical Li deintercalation of Li1−xMn2−yCryO4 (y=1/9,1/6,1/3) were studied by the in situ X-ray absorption fine structure (XAFS) technique. The X-ray absorption near-edge structures (XANES) of Mn and Cr as a function of x showed that the 4 V plateau of the material can be ascribed to the oxidation of Mn3+ to Mn4+, and Cr does not contribute to the charging, but to the stabilization of the spinel structure against the delithiation. The extended EXAFS analysis of Li1−x(Mn, Cr)2O4 revealed that the Jahn–Teller distorted Mn3+–O octahedra become uniform when the cell is fully charged.