Cathode Properties of xLiF–LiCrO2 Composites (x = 0–1.5) Prepared by Dry Ball-Milling Method for Lithium Ion Batteries

The xLiF–LiCrO2 series, prepared using the dry ball-milling method, was investigated to improve the electrochemical properties of LiCrO2. The addition of LiF to LiCrO2 changed the Cr oxidation state, and its rechargeable capacity increased to greater than that of milled-LiCrO2. The Li–O(F) correlation for xLiF–LiCrO2 was split in two by the dry ball-milling treatment, unlike the case with layered LiCrO2. In addition, the dispersion state of Li and Cr in the particles changed, and part of the Cr oxidation state shifted from +3 to +4 with the addition of LiF to LiCrO2. The reversible capacity increased with increasing x in xLiF–LiCrO2 at x ≤ 0.7, and the number of reacted electrons increased with increasing x in xLiF–LiCrO2. Cr K-edge and L-edge XANES spectra clarified that the charge–discharge reaction for milled-LiCrO2 and xLiF–LiCrO2 proceeds by only Cr3+/Cr6+ redox couples.