高电压正极材料LiNi0.5Mn1.5O4的制备及其倍率性能

摘要

采用溶胶凝胶法制备尖晶石型高电压正极材料LiNi0.5Mn1.5O4,并掺杂F-与之对比.分别采用X射线衍射仪、电子扫描显微镜、热重分析仪、电化学工作站和充放电测试仪对合成材料的物相、形貌和电化学性能进行表征.结果表明,0.5C倍率下LiNi0.5Mn1.5O4首次放电比容量高达141.6 mAh/g,接近于理论比容量146.7 mAh/g.提高倍率40次循环后,5C比容量仍有111.8 mAh/g,而F-掺杂样品仅有92 mAh/g.然后从5C返回到1C,比容量为129.9 mAh/g,与1C初始容量相比,容量保持率高达96.4％,LiNi0.5Mn1.5O4显示出更加优异的倍率循环性能.%Spinel LiNi0.5Mn1.5O4 was synthesized by sol-gel method using Ni(CH3COO)·4H2O、Mn(CH3COO)·4H2O and Li (CH3COO)·2H2O as raw materials,compared with F-doping sample.The morphology and microstructure of the materials were characterized by XRD,SEM,TG-DTA,the electrochemical workstation and charge-discharge tester showed the electrochemical performance.The results show that the initial discharge specific capacity of LiNi0.5Mn1.5O4 is 141.6 mAh/g at 0.5C closed to the theoretical specific capacity.After 40th cycles,the discharge specific capacity is still 111.8 mAh/g at 5C,however,the F-doped sample is only 92 mAh/g.Returning to 1 C,the discharge specific capacity is 129.9 mAh/g.The capacity retention is 96.4％ compared with the initial capacity at 1 C,which shows that LiNi0.5Mn1.5O4 has better rate cycling capability.