碳热还原法制备V2O3-C双层包覆磷酸铁锂及其电化学性能

通过V₂O₅的碳热还原反应制备了具有优异倍率性能和循环稳定性的V₂O₃-C双层包覆的磷酸铁锂正极材料. 粉末X射线衍射、元素分析、高分辨投射电镜和拉曼光谱研究表明V2O3相与碳层共包覆于磷酸铁锂颗粒表面. 在V₂O₅的碳热还原反应后，碳含量明显降低，但石墨化程度未发生明显改变. 电化学测试结果表明少量V₂O₃显著改善了磷酸铁锂正极材料的倍率性能和高温循环性能，包含1%氧化钒的复合正极材料在0.2 C放电容量为167 mAh/g，5 C时放电容量为129 mAh/g，并且循环稳定性优异；在55 oC和1 C时放电容量为151 mAh/g，循环100次后无明显容量衰减.

Preparation and Electrochemical Performance of V2O3-C Dual-Layer Coated LiFePO4 by Carbothermic Reduction of V2O5

The V₂O₃-C dual-layer coated LiFePO₄ cathode materials with excellent rate capability and cycling stability were prepared by carbothermic reduction of V₂O₅. X-ray powder diffraction, elemental analyzer, high resolution transmission electron microscopy and Raman spectra revealed that the V₂O₃ phase co-existed with carbon in the coating layer of LiFePO₄ particles and the carbon content reduced without graphitization degree changing after the carbothermic reduction of V₂O₅. The electrochemical measurement results indicated that small amounts of V₂O₃ improved rate capability and cycling stability at elevated temperature of LiFePO₄/C cathode materials. The V₂O₃-C dual-layer coated LiFePO₄ composite with 1wt% vanadium oxide delivered an initial specific capacity of 167 mAh/g at 0.2 C and 129 mAh/g at 5 C as well as excellent cycling stability. Even at elevated temperature of 55 oC, the specific capacity of 151 mAh/g was achieved at 1 C without capacity fading after 100 cycles.