(中南大学 化学化工学院，长沙 410083)
摘 要: 为了提高LiFePO4的电化学性能，以柠檬酸为络合剂和碳源，采用溶胶−凝胶法制备LiFePO4/C复合正极材料。采用FTIR和XRD等对前驱体及产物进行表征，并测试样品的电化学性能。结果表明：经700 ℃烧结10 h所得产物具有单一的橄榄石型晶体结构，碳含量为10.81%(质量分数)。 样品在0.1C下首次放电比容量为127.1 mA∙h/g，在0.2C、0.5C、1C下首次放电比容量分别为106.1、83.3、70.6 mA∙h/g。 该样品在0.1C下经过20次循环后，容量还保持为126.3 mA∙h/g，衰减仅为0.035%。循环伏安和交流阻抗测试表明该材料具有较好的电化学性能。
关键字: 锂离子电池；正极材料；LiFePO4；溶胶−凝胶法
sol-gel method and its performance
（School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China）
Abstract:To improve the performance of LiFePO4, LiFePO4/C composite cathode materials were synthesized by sol-gel method using citric acid as chelant and carbon source. The precursors and the products were characterized by FTIR and XRD, and the electrochemical performance of the samples was measured. The results show that the composite synthesized at 700 ℃ has a simple pure olive-type phase with 10.81%(mass fraction) carbon content. The sample can deliver a discharge capacity of 127.1 mA∙h/g at 0.1C. The first special discharge capacities of LiFePO4 at 0.2C, 0.5C and 1C are 106.1, 83.3 and 70.6 mA∙h/g, respectively. It retains discharge capacity of 126.3 mA∙h/g at 0.1C after 20 cycles, with only 0.035% capacity decrment．The sample exhibits good electrochemical performance, proved by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests.
Key words: Li ion battery; cathode material; LiFePO4; sol-gel method
