改进固相法合成LiNi_xCo_yMn_(1-x-y)O_2正极材料及性能研究

Synthesis of LiNi_xCo_yMn_(1-x-y)O_2 cathode material by improved solid-state method and its property studies

采用固相法制备正极材料LiNi1/3Co1/3Mn1/3O2,用X射线衍射仪（XRD）、扫描电子显微镜（SEM）/透射电镜（TEM）分析材料的结构和形貌特征,用LAND电池测试系统测试材料的电化学性能（充放电容量和循环性能等）。以LiOH.H2O,H2C2O4.2H2O,Ni（AC）2.4H2O,Co（AC）2.4H2O和Mn（AC）2.4H2O为原料,采用固相法在不同煅烧温度和煅烧时间下制备的层状正极材料LiNi1/3Co1/3Mn1/3O2具有典型的α-NaFeO2型层状结构特征,晶型结构完整。电化学性能测试结果表明,在850℃下保温15 h合成的正极材料电化学性能最优,在电流密度为120 mA/g、充放电电压在2.75~4.5 V时,经30次循环后放电比容量为163.5 mA.h/g,容量保持率为94% 50次循环后为157.2 mA.h/g,容量保持率为90.8%。

Solid-state method were adopted to synthesize LiNi1/3 Co1/3 Mn1/3 O2 cathode material. XRD, SEM/TEM, and LAND battery test system were used to study microstructure, morphology, and electrochemical performance （charge-discharge capacity,cycling performance and so on） of the material. LiNi1/3Co1/3Mn1/3 O2 cathode material was synthesized by solidstate method at different calcination-temperatures and - times with LiOH · H2O, H2C2O4 · 2H2O, Ni（AC）2 · 4H2O, Co （AC）2·4H2O, and Mn （AC）2 · 4H2O as raw materials. Results showed that all the samples were layered materials with typical α - NaFeO2 structure, and crystal structure was good. Electrochemical test indicated the sample prepared at 850 ℃ for 15 h had the highest discharge capacity;after 30 cycles,the discharge capacity was 163.5 mA · h/g and the capacity retention was 94% ;after 50 cycles, it still had the discharge capacity of 157.2 mA · hg and the capacity retention was 90.8% when the current density and charge-discharge voltage were 120 mA/g and 2.75 -4.5 V respectively.