Local Structure and First Cycle Redox Mechanism of Layered Lisub 1.2Crsub 0.4Mnsub 0.4Osub 2 Cathode Material

Electrochemical, X-ray diffraction, and K and L edge X-ray absorption data are reported for the layered cathode material Li₁.₂Mn₀.₄Cr₀.₄O₂. The structural data show that this material can be understood as a solid solution of the layered phases Li₂MnO₃ and LiCrO₂, comprising tretravalent Mn and trivalent Cr, with approximately 0.2 lithium incorporated in the transition metal layers. According to the analysis of the K edge extended X-ray absorption fine structure, lithium ions in the transition metal layers are clustered around Mn ions. L edge X-ray absorption near edge spectra show that in the first charge-discharge cycle chromium is the electrochemically active species, cycling between Cr³⁺ and Cr⁶⁺ Manganese remains as Mn⁴⁺ throughout charge and discharge. © 2002 The Electrochemical Society. All rights reserved.