Effect of LiI Amount to Enhance the Electrochemical Performance of Carbon-Coated LiFePO4

We used the wet chemistry method with different amounts of LiI to prepare LiFePO4 and carbon-coated LiFePO4 (LiFePO4/C) samples. The lithiation process of LiI for preparing the LiFePO4 is proposed. We found that the amount of LiI greatly affected the purities of products. The LiFePO4/C sample showed constant values of current density during potential cycling up to 35 cycles as compared to LiFePO4, suggesting that the LiFePO4/C has better electrochemical performance. The obtained maximum capacity for LiFePO4/C can be approached to the theoretical capacity of 170 mAh/g. Moreover, Brunauer-Emmett-Teller measurements of LiFePO4 and LiFePO4/C showed a surface area of 6.7 and 50 m(2)/g, respectively. It is reasonable to believe that the excellent performance of the compound developed in our work can be attributed to the smaller particle size coated with conductive carbon achieved by the controlling LiI in the sol-gel method.