锂离子电池正极材料LiFePO_4/C的制备及电化学性能研究  

Fabrication and electrochemical properties of LiFePO_4/ C cathode materials

作　　者：徐可[1] 游才印[1] 王钦[1] 张卫华[1] 郭少华[1] 

机构地区：[1]西安理工大学材料科学与工程学院,陕西西安710048

出　　处：《西安理工大学学报》2016年第1期96-99,105,共5页Journal of Xi'an University of Technology

基　　金：国家国际科技合作专项基金资助项目(2015DFR50350);陕西省自然科学基金资助项目(2013JQ6008)

摘　　要：分别以葡萄糖和柠檬酸为碳源,通过碳热还原法合成橄榄石结构的LiFePO_4/C正极材料。采用X射线衍射(XRD)及透射电子显微镜(TEM)对产物的结构表面和微观形貌进行了分析,通过恒流充放电以及交流阻抗谱(EIS)表征了产物的电化学性能,探讨了产物容量衰减的原因。结果表明:以葡萄糖为碳源的产物结晶度好,晶粒尺寸小。恒流充放电测试显示其具有更好的电化学性能:0.2 C倍率下首次放电比容量为140.2 m Ah/g,循环50次后基本无衰减;1 C的首次放电比容量也达到了120.5 m Ah/g。此外,在高倍率充放电过程中,交流阻抗谱显示LiFePO_4/C的扩散系数减小,约为1.798×10^(-12)cm^2/s。The olivine-structured LiFePO_4/ C cathode material is synthesized with glucose and citric acid as carbon sources via the carbothermal reduction method. X-ray diffraction（ XRD） and transmission electron microscopy（ TEM） are used to carry out the analysis of the product structure surface and micromorphology. The product electrochemical properties are characterized through the galvanostatic chargedischarge tests and electrochemical impedance spectroscope（ EIS）. The product capacity attenuation is discussed. The results show that the product of glucose as carbon source has good crystallinity with small grain size. Galvanostatic charge-discharge tests indicate that it has better electrochemical performance：The initial discharge capacity is 140. 2 m Ah / g at 0. 2 C rate,almost no attenuation after 50 cycles. The capacity at 1 C reaches 120. 5 m Ah / g. In addition,electrochemical impedance spectroscope shows that the diffusion coefficient of LiFePO_4/ C decreases at the process of high rate,about 1. 798 × 10^（-12）cm^2/ s.

关 键 词：正极材料 磷酸铁锂 碳热还原 容量衰减 

分 类 号：TM912[电气工程—电力电子与电力传动]