中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 25 No. 6 June 2015 |
（1. School of Chemistry, Xiangtan University, Xiangtan 411105, China;
2. College of Chemistry and Bioengineering, Guilin University of Technology, Guilin 541004, China;
3. College of Chemistry and Chemical Engineering, Hunan Institute of Engineering, Xiangtan 411104, China）
Abstract:The Li3-2xMgxV2(PO4)3/C (x=0, 0.01, 0.03 and 0.05) composites were prepared by a sol-gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurements. The XRD results reveal that a small amount of Mg2+ doping into Li sites does not significantly change the monoclinic structure of Li3V2(PO4)3, but Mg-doped Li3V2(PO4)3 has larger cell volume than the pristine Li3V2(PO4)3. All Mg-doped composites display better electrochemical performance than the pristine one, and Li2.94Mg0.03V2(PO4)3/C composite exhibits the highest capacity and the best cycle performance among all above-mentioned composites. The analysis of Li+ diffusion coefficients in Li3V2(PO4)3/C and Li2.94Mg0.03V2(PO4)3/C indicates that rapid Li+ diffusion results from the doping of Mg2+ and the rapid Li+ diffusion is responsible for the better electrochemical performance of Mg-doped Li3V2(PO4)3/C composite cathode materials.
Key words: lithium-ion batteries; lithium vanadium phosphate; diffusion coefficient; sol-gel method
