Comparing the electrochemical performance of LiFePO4/C modified by Mg doping and MgO coating

Abstract

Supervalent cation doping and metal oxide coating are the most efficacious and popular methods to optimize the property of LiFePO4 lithium battery material. Mg-doped and MgO-coated LiFePO4/C were synthesized to analyze their individual influence on the electrochemical performance of active material. The specific capacity and rate capability of LiFePO 4/C are improved by both MgO coating and Mg doping, especially the Mg-doped sample - Li0.985Mg0.015FePO4/C, whose discharge capacity is up to 163 mAh g-1, 145.5 mAh g-1, 128.3 mAh g-1, and 103.7 mAh g-1 at 1 C, 2 C, 5 C, and 10 C, respectively. The cyclic life of electrode is obviously increased by MgO surface modification, and the discharge capacity retention rate of sample LiFePO4/C-MgO2.5 is up to 104.2% after 100 cycles. Comparing samples modified by these two methods, Mg doping is more prominent on prompting the capacity and rate capability of LiFePO4, while MgO coating is superior in terms of improving cyclic performance. © 2013 Jianjun Song et al.