喷雾干燥法制备石墨烯包覆富锂锰基材料Li1.22Mn0.52Ni0.26O2及其电化学性质

Preparation of graphene-coated Li1.22Mn0.52Ni0.26O2 using a spray drying method for lithium-ion batteries

本工作采用喷雾干燥法制备了小片径石墨烯包覆的Li1.22Mn0.52Ni0.26O2富锂锰基材料(G-LNMO),系统研究了包覆前后材料的晶体结构、微观形貌及电化学性质。扫描电镜(SEM)及透射电镜(TEM)结果表明,该方法实现了石墨烯对富锂锰基材料(LNMO)的均匀包覆。充放电测试表明,石墨烯包覆后将LNMO材料在0.1 C和1 C倍率下的放电容量分别从199.8 mA·h/g和87.1 mA·h/g提升至220.2 mA·h/g和117.6 mA·h/g。在0.5 C倍率下经过100次循环后,G-LNMO材料的容量保持率为88%,相比于LNMO材料提升了17%。电池充放电曲线及电化学阻抗分析显示,石墨烯包覆能够显著提升电极动力学,降低电池在充放电过程中的极化,减缓电极/电解液界面副反应的发生,进而提升材料的循环稳定性和倍率性能。

A graphene-coated lithium rich manganese-based composite(G-LNMO)was synthesized using spray drying and was investigated as cathode material for lithium-ion batteries.The effect of graphene coating on the electrochemical performance was investigated systematically.Scanning electron microscopy(SEM)and transmission electron microscopy(TEM)images revealed that in G-LNMO,graphene nanosheets are uniformly dispersed and particles of Li1.22Mn0.52Ni0.26O2 are coated with the graphene nanosheets.Charge-discharge curves and electrochemical impedance spectroscopy(EIS)indicate that the structure of particles coated by graphene nanosheets can enhance the electron migration and alleviate the polarization of a pristine sample,leading to improved cycling stability and a high-rate capability.At 0.1 C and 0.5 C,the pristine and graphene-coated samples delivered capacities of 199.8 and 220.2 mA·h/g,and after 100 cycles,retained a capacity of 71%and 88%,respectively.This simple and scalable approach can be applied to the industrial production of graphene coated and lithium rich manganese-based oxides.