摘要
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Li2-xKxFeSiO4-0.5xClx/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电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Li1.99K0.01FeSiO3.995Cl0.01/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Li1.99K0.01FeSiO3.995Cl0.01/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％.
Abstract
Herein,the structure and electrochemical properties of nano Li2FeSiO4/C cathode materials were opti-mized through co-doping potassium and chlorine ions.A series of nano Li2-xKxFeSiO4-0.5xClx/C(x=0,0.01,0.02)com-posites 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 Li1.99K0.01FeSiO3.995Cl0.01/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 Li1.99K0.01FeSiO3.995Cl0.01/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 Li1.99K0.01FeSiO3.995Cl0.01/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 Li1.99K0.01FeSiO3.995Cl0.01/C cathode material at 1C after 100 charge-discharge cycles.
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