不同碳源LiFePO_4/C复合材料的表征与性能分析

Characterization and performance analysis of LiFePO_4/C composite made from different carbon materials

以FePO4.2H2O,LiOH.H2O为原料,分别以蔗糖、PVA、柠檬酸及三者按一定比例混合做为包覆碳的碳源,经碳热还原法合成得到LiFePO4/C复合正极材料。采用TG/DTA、XRD、SEM对前驱体及产物进行表征。以放电比容量为考察样品电化学性能的指标。实验发现,以蔗糖、柠檬酸、PVA按一定比例混合为碳源制得的LiFePO4/C复合材料电化学性能最好,在0.5,1,2,和5 C下首次充放电分别达到144.5,138.5,130.3和110.7 mAh/g,样品在5 C下经50次循环,基本无衰减。

Lithium iron phosphate was synthesized by carbothermal reduction method with FePO4·2H2O and LiOH·H2O and with citrate,glucose,PVA and the mixture of the three with certain ratio as the sources of carbon.The precursor and the products were characterized by TG/DTA,XRD,and SEM.The electrochemical performance of the samples was measured.The results showed that the LiFePO4/C composite synthesized with the mixture of citrate,glucose,and PVA as the carbon source exhibited the most excellent electrochemical performance.The first discharge capacities at 0.5C,1C,2C,5C were 144.5mAh/g,138.5 mAh/g,130.3 mAh/g,and 110.7 mAh/g respectively.After 50 cycles at 5C,the discharge capacity of the sample did not show any obvious decrease.