炭包覆LiFePO4纳米片的制备及电化学性能研究

为改善磷酸铁锂正极材料的倍率性能, 以乙二醇为溶剂, 采用一步溶剂热法制备磷酸铁锂纳米片。再以葡萄糖为碳前驱体, 对磷酸铁锂纳米片进行炭包覆。通过X射线衍射, N₂吸脱附曲线、扫描电子显微镜、透射电子显微镜和循环伏安法等测试方法考察了炭包覆量对磷酸铁锂纳米片结构与电化学性能的影响。结果表明, 制备的磷酸铁锂为具有较短b轴的纳米片状结构, 尺寸约为150 nm×100 nm×60 nm。磷酸铁锂纳米片的倍率性能随炭包覆量的增加而增强, 当炭包覆量为6.4wt%时具有最佳的倍率性能, 在0.2C和10C的电流密度下放电容量分别为157.3和132.6 mAh/g。同时循环稳定性良好, 在5C电流密度下循环500次后容量保持率达到了80.2%。

Synthesis and Electrochemical Property of Carbon Coated LiFePO4 Nanoplates

To improve the rate performance of LiFePO₄ cathode material, LiFePO₄ nanoplates were synthesized via one-step glycol-based solvothermal process. Additionally, carbon was employed to coat LiFePO₄ with glucose served as carbon source. The morphologies and electrochemical properties of the as-prepared materials were characterized by XRD, BET, SEM, TEM, cyclic voltammetry, etc. Results showed that LiFePO₄ nanoplates had the size of approximately 150 nm×100 nm×60 nm, displaying a short b-axis. The rate performance of LiFePO₄ nanoplates was enhanced with the increment of carbon content, and the sample containing 6.4wt% carbon (LF0.2) exhibited the most outstanding electrochemical performance, which delivered discharge capacities of 157.3 mAh/g and 132.6 mAh/g at 0.2C and 10C rates, respectively. Meanwhile, excellent cycling stability of LF0.2, 80.2% capacity retention after 500 cycles at 5C rate, was observed.