(中南大學 化學化工學院，長沙 410083)
摘 要: 為了提高LiFePO4的電化學性能，以檸檬酸為絡合劑和碳源，采用溶膠−凝膠法制備LiFePO4/C復合正極材料。采用FTIR和XRD等對前驅(qū)體及產(chǎn)物進行表征，并測試樣品的電化學性能。結(jié)果表明：經(jīng)700 ℃燒結(jié)10 h所得產(chǎn)物具有單一的橄欖石型晶體結(jié)構(gòu)，碳含量為10.81%(質(zhì)量分數(shù))。 樣品在0.1C下首次放電比容量為127.1 mA∙h/g，在0.2C、0.5C、1C下首次放電比容量分別為106.1、83.3、70.6 mA∙h/g。 該樣品在0.1C下經(jīng)過20次循環(huán)后，容量還保持為126.3 mA∙h/g，衰減僅為0.035%。循環(huán)伏安和交流阻抗測試表明該材料具有較好的電化學性能。
關鍵字: 鋰離子電池；正極材料；LiFePO4；溶膠−凝膠法
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
