钾、氯离子共掺杂纳米Li2FeSiO4/C正极材料的电化学性能

利用K⁺、Cl^-共掺杂来优化纳米Li₂FeSiO₄/C正极材料的结构及电化学性能,通过固相反应制备了纳米Li_2-xK_xFeSiO_4-0.5xCl_x/C(x=0、0.01、0.02)正极材料。采用X射线衍射、扫描电子显微镜、透射电子显微镜、X射线光电子能谱和恒流充放电等对比研究了3种正极材料的微观结构特征和电化学性能。研究表明纳米Li_1.99K_0.01FeSiO_3.995Cl_0.01/C正极材料的晶面间距和晶胞体积最大,颗粒粒径最小,平均粒径为32 nm。这些特定的微观结构使其表现出最优的电化学性能。纳米Li_1.99K_0.01FeSiO_3.995Cl_0.01/C在0.1C下的首次放电比容量高达203 mAh·g^-1,在1C下充放电循环100次的容量保持率为97.72%。

Performance of nano Li2FeSiO4/C cathode material co-doped by potassium and chlorine ions

Herein, the structure and electrochemical properties of nano Li₂FeSiO₄/C cathode materials were optimized through co-doping potassium and chlorine ions. A series of nano Li_2-xK_xFeSiO_4-0.5xCl_x/C (x=0, 0.01, 0.02) composites were prepared by a solid-state reaction. The microstructure and electrochemical performance of the three kinds of composites were analyzed using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, constant current charge-discharge test, etc. The results showed that nano Li_1.99K_0.01FeSiO_3.995Cl_0.01/C cathode material owned the largest interplanar spacing, biggest cell volume, and smallest average particle size among the three materials. The average particle size of nano Li_1.99K_0.01FeSiO_3.995Cl_0.01/C cathode material was as small as 32 nm. These particular structures made it exhibit the best electrochemical performance. The initial specific discharge capacity of the nano Li_1.99K_0.01FeSiO_3.995Cl_0.01/C cathode material at 0.1C was as high as 203 mAh·g^-1. In addition, a capacity retention rate of 97.72% was acquired for the nano Li_1.99K_0.01FeSiO_3.995Cl_0.01/C cathode material at 1C after 100 charge-discharge cycles.