The distinct role of transition metal doping for LiFePO ₄ cathode material

This study addresses the controversial issue of the effect of metal ion doping on the electrochemical performance of LiFePO ₄. Metal doping is claimed to be a possible cause for the capacity improvement of LiFePO ₄ as carbon coating. Results obtained inthis study show that dry-milled LiFePO ₄ and LiFe _0.9Cr _0.1PO ₄ deliver 119 mAh g ^-1 and 101 mAh g ^-1 , while wet-milled LiFePO ₄ and LiFe _0.9Cr _0.1PO ₄ deliver 149 mAh g ^-1 and 138 mAh g ^-1 , respectively. This indicates that the capacity improvement by metal doping is due to the carbonaceous materials produced during fabrication and not by the enhancement of ion diffusion. On the other hand, cycle test results show that metal doping enhances the rate capability at high C-rates by accelerating lithium ion diffusion.