正极材料LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2的制备及性能研究

Preparation and characterization of cathode material LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2

以柠檬酸为络合剂,乙二醇为交联剂,通过Pechini法制备出锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2。采用X射线衍射光谱法(XRD)、扫描电子显微镜(SEM)、恒流充放电测试对材料的结构、形貌和电化学性能进行表征。实验结果表明在850℃下保温6 h合成出的LiNi1/3Co1/3Mn1/3O2具有最佳的层状结构和纳米级的一次均匀颗粒,且该条件下由LiNi1/3Co1/3Mn1/3O2/碳纳米管(质量比为90∶5)作为正极复合材料制作的电池电化学性能最佳。在2.5-4.5 V进行恒流充放电测试,0.2 C下首次放电比容量为219.6 mAh/g,倍率性能佳,在1 C下充放电首次比容量为158.7 mAh/g,且循环性能优良,在60次循环以后,容量保持率为91.25%。

LiNi1/3Co1/3Mn1/3O2 used as cathode material for Li-ion batteries was synthesized via Pechini method with citric acid and ethylene glycol as the chelating agent and crosslinking agent.The structure,morphology and electrochemical performance characterization of the samples were investigated by X-ray diffraction（XRD）,scanning electron microscope（SEM）,and galvanostatic charge-discharge tests.The results show that the samples prepared by Pechini method caclined at 850 ℃ for 6 h are indexed to pure LiNi1/3Co1/3Mn1/3O2 with well hexagonal structure,nanoscale sizes and uniform crystals.The composite electrode LiNi1/3Co1/3Mn1/3O2/CNTs（the ratio of mass is about 90 to 5） under this synthesis conditions exhibits a superior electrochemical performance.The initial discharge specific capacity of the sample is 219.6 mAh/g at 0.2 C rate and in the range 2.5-4.5 V.In addition,the cell delivers a discharge specific capacity of 158.7 mAh/g at 1 C rate.More than 91.25% of the capacity is retained after 60 cycles.