中文摘要：

采用溶胶凝胶法，以LiOH，Fe2C2O4和NH4H2PO4为原材料，以乙二醇为络合剂和碳源，通过对合成LiFePO4的前驱体在不同温度和时间的分步煅烧，获得了兼具良好结晶性、亚微米颗粒尺寸和含适量原位引入Fe2P的LiFePO4／C复合材料，该材料作为锂离子电池正极材料表现出优良的倍率性能．采用x射线衍射、扫描电子显微镜、元素分析等方法和恒电流充放电等测试技术对获得的LiFePO4／C材料的结构和电化学性能进行研究．结果表明，分步联合煅烧是综合实现适量Fe2P相的原位引入、LiFePO4颗粒尺寸控制和提高LiFePO4结晶性的有效途径，其显著提高了LiFePO4／C材料的高倍率性能．经600℃煅烧20h再经700℃煅烧4h获得的含4wt％Fe2P和3wt％C的LiFePO4／C复合正极材料，在1，10和20C放电条件下的放电容量分别达到140，110和100mANg．

英文摘要：

LiFePO4/C composite with high crystallinity, sub-micron particle size and suitable content of in-situ introduced Fe2P was synthesized by a sol-gel method, in which LiOH, Fe2C2O4 and NH4H2PO4 were used as starting materials, and ethylene glycol was used as complexing agent and carbon source. The precursor of LiFePO4 was calcined at a comparatively low temperature for relatively long time combined a following calcination at a comparatively high temperature for relatively short time. The composite shows high-rate capability as cathode material for lithium-ion batteries. The structure and the electrochemical properties of the LiFePO4/C composites synthesized by different calcination parameters were analyzed by X-ray diffraction, scanning electron microscopy, element analysis and electrochemical testing of galvanostatic charge-discharge, etc. The results show that the step-wise calcination at different temperatures for different times is an effective approach to obtain suitable amount of in-situ Fe2P, control the particle size and enhance the crystallinity of LiFePO4, which results in a significant improvement in the high-rate capability of LiFePO4. The LiFePO4/C composite synthesized at a calination temperature of 600℃ for 20 h followed by a further calcination at 700℃ for 4 h has 4wt% Fe2P and 3wt% C. The composite possesses discharge capacities of 140, 110 and 100 mAh/g at discharge rates of 1, 10 and 20 C, respectively.