溶胶凝胶法合成富锂正极材料Li[Li0.2Ni0.2Mn0.6]O2及性能表征

以LiOH.H2O、Mn(CH3COO)2.4H2O和Ni(CH3COO)2.4H2O为原料,分别用柠檬酸(CA)与乙二胺四乙酸(EDTA)为配位剂,采用溶胶凝胶法结合固相烧结法制备富锂固溶体正极材料LiLi0.2Ni0.2Mn0.6]O2。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、激光粒度仪对所得样品的结构、形貌、粒径分布进行了表征,并测试了材料的电化学性能。采用CA配位制备的材料的电化学性能优于用EDTA配位制备的材料的电化学性能,室温下以18 mA.g-1的电流密度,在2.0~4.8 V电压范围内充放电,用CA制备的材料首次充电比容量高达324 mAh.g-1,首次库伦效率达82%;在180 mA.g-1的电流下,其可逆比容量保持在120 mAh.g-1。

Characterization of Li-Rich Cathode Material Li[Li0.2Ni0.2Mn0.6]O2 Synthesized by Sol-Gel Method for Lithium-Ion Batteries

Li-rich solid solution cathode material LiLi_0.2Ni_0.2Mn_0.6]O₂ was synthesized by a sol-gel method and subsequent solid-state sintering process, using LiOH·H₂O, Mn(CH₃COO)₂·4H₂O and H₃COO)₂·4H₂O as raw materials, and citric acid (CA) and ethylene diamine tetraacetic acid (EDTA) as chelating agents, respectively. The as-synthesized materials were characterized by X-ray diffraction, scanning electron microscope and Laser Particle Size Analyzer, and the electrochemical properties of materials were investigated. The material using CA as chelating agent showed higher capacity and better rate performance than that using EDTA as chelating agent. The half-cell of Li/LiLi_0.2Ni_0.2Mn_0.6]O₂ using CA as chelating agent delivered a charge specific capacity of 324 mAh·g^-1 with an initial efficiency of 82% at a current density of 18 mA·g^-1 between 2.0 and 4.8 V, and retained the reversible capacity of 120 mAh·g^-1 even at a high current density of 180 mA·g^-1.