LiFeP0.95B0.05O4-δ/C的制备及电化学性能研究

doi:10.3724/SP.J.1077.2010.00230

摘要/Abstract

摘要： 以柠檬酸为螯合剂和碳源, 采用溶胶凝胶法合成了B在P位掺杂的LiFeP_0.95B_0.05O_4-δ/C复合材料. 通过XRD、CV、恒流充放电测试等手段对晶体结构和电化学性能进行研究. 结果表明, 复合材料具有单一的橄榄石型晶体结构, B在P位掺杂可提高材料的导电性能, 降低电极极化, 能有效改善材料的循环性能和高倍率性能. 650℃下合成的LiFeP_0.95B_0.05O_4-δ/C复合材料在0.2、5、10C的首次放电比容量分别为149.3、123.4和112.1mAh/g, 其容量保持率分别为99.3％（0.2C, 20次）、91.65％（5C, 150次）和92.9％（10C, 150次）, 不同倍率下持续充放电30次后, 0.2C放电容量仍能恢复至初始值.

关键词: 锂离子电池, 正极材料, 磷酸铁锂, 硼掺杂

Abstract: B-doped LiFePO₄ in P-site, LiFeP_0.95B_0.05O_4-δ/C composite materials were synthesized in flowing Ar atmosphere by solgel method, using citric acid as chelating agent and carbon source. Samples were characterized by X-ray diffraction and cyclic voltammetry, and their electrochemical performances were investigated by galvanostatic charge/discharge tests in terms of cycling performance and rate capability．The results show that the samples have wellregulated olivinetype structures without any impurity peaks while B-doping improves the conductivity of composite materials and decreases the polarization of electrode, and enhances the cycling performance and rate capability effectively. The discharge capacities of LiFeP_0.95B_0.05O_4-δ/C synthesized at 650℃ are 149.3, 123.4 and 112.1 mAh/g at the rates of 0.2C, 5C and 10C, with retention ratio of 99.3% after 20 cycles at the rate of 0.2C, 91.65% after 150 cycles at the rate of 5C and 92.9% after 150 cycles at the rate of 10C, respectively. After continuous 30 cycles at different rates of 0.2, 1, 3, 5 and 10C, the discharge capacity of 0.2C can reconvert to the previous value.

Key words: lithium-ion battery, cathode material, lithium iron phosphate, B-doping

中图分类号:

TM921

任兆刚,瞿美臻,于作龙. LiFeP_0.95B_0.05O_4-δ/C的制备及电化学性能研究[J]. 无机材料学报, DOI: 10.3724/SP.J.1077.2010.00230.

REN Zhao-Gang,QU Mei-Zhen,YU Zu-Long. Synthesis and Electrochemical Properties of LiFeP_0.95B_0.05O_4-δ/C Cathode Materials[J]. Journal of Inorganic Materials, DOI: 10.3724/SP.J.1077.2010.00230.

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