固体电解质Li_5La_3Ta_2O_(12)包覆LiMn_2O_4的改性研究

Modification of Li_5La_3Ta_2O_(12) coated LiMn_2O_4

采用溶胶-凝胶的方法低温制备石榴石结构的固体电解质Li5La3Ta2O12,并用其包覆Li Mn2O4来改善材料的电化学性能。通过XRD,SEM和TEM等表征手段对材料的结构和形貌进行分析,并通过恒电流充放电、循环伏安、交流阻抗等测试分析材料的电化学性能。研究结果表明:Li5La3Ta2O12包覆的Li Mn2O4材料与未包覆的材料相比,其电化学性能得到明显改善,经过150次循环后包覆材料的放电比容量保持率为92%,在高倍率10C(C为倍率)下包覆材料放电比容量为61.2 m A·h/g,而未包覆材料放电比容量仅为40.7 m A·h/g;包覆Li5La3Ta2O12后,Li Mn2O4的阻抗明显减小,大幅度提高了其循环性能和倍率性能。

Li Mn2O4,Li5La3Ta2O12（LLTO） was prepared by sol-gel method and it was employed as a coating layer on the surface of Li Mn2O4. The structure and morphology of the material were analyzed by XRD, SEM and other characterization methods. The electrochemical performance of the material was analyzed by galvanostatic charge-discharge experiments, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the electrochemical performance of the LLTO-coated Li Mn2O4 is improved significantly. The resistance of LLTO-coated Li Mn2O4 is reduced significantly. After 150 cycles test, the discharge capacity retention rate of the coated material is92%.At the high-rate of 10 C, the discharge capacity of the LLTO-coated Li Mn2O4 is 61.2 m A·h/g and that of the uncoated material is 40.7 m A·h/g. The impedance of LLTO-coated Li Mn2O4 decreases evidently, therefore the cycle performance and rate capability increase greatly.