(中南大學 冶金科學與工程學院，長沙 410083)
摘 要: 以LiH2PO4和FeC2O4•2H2O為原料，聚乙烯醇為碳源，通過機械化學活化輔助固相法合成原位碳包覆的LiFePO4材料；考察合成溫度對LiFePO4/C材料晶體結構、物理和電化學性能的影響。結果表明：700 ℃下處理的產(chǎn)物結晶良好、分布均勻、顆粒細小；在最佳的熱處理條件下，熱解碳在LiFePO4顆粒表面形成了良好的納米導電層，LiFePO4/C材料在0.1C、0.5C、1C和2C倍率下放電比容量分別為155.7、150.1、140.1和130 mA•h/g，且材料在0.1~2C范圍內(nèi)充放電都有很平穩(wěn)的平臺，極化小，并具有較高的高倍率(2C)放電比容量和較好的循環(huán)性能。
關鍵字: 聚陰離子型正極材料；LiFePO4；原位碳包覆；機械活化法
material by solid state reaction and its performance
（School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China）
Abstract:In-situ carbon-coated LiFePO4 cathode material was prepared by ball-milling activation and subsequent solid state reaction with LiH2PO4 and FeC2O4•2H2O as starting materials, and polyvinyl alcohol (PVA) as carbon source. The effects of synthetic temperature on the crystal structure, physical property and electrochemical performance of LiFePO4/C composites were studied. The results show that 700 ℃ is the optimal synthetic temperature. Under this temperature, the pyrolytic carbon forms an excellent nano conducting layer on the surface of LiFePO4 particles. The discharge capacities of the sample at 0.1C, 0.5C, 1C and 2C rate are 155.7, 150.1, 140.1 and 130 mA•h/g, respectively. The sample has a very stable discharge plateau, mild polarization, preferable high rate performance between 0.1C and 2C rate which displays good cyclic capability and higher reversible discharge specific capacity at 2C rate.
Key words: polyanion cathode materials; LiFePO4; in-situ carbon coating; ball-milling activation method
