Li3PO4包覆改善LiNi0.5Co0.2Mn0.297Al0.003O2材料性能研究

Research on the performance improvement of Li3PO4 coated LiNi0.5Co0.2Mn0.297Al0.003O2

利用共沉淀反应合成Ni0.5Co0.2Mn0.297Al0.003O2前驱体,配锂经高温烧结(920℃-12 h)制得平均粒径为9μm的LiNi0.5Co0.2Mn0.297Al0.003O2材料。采用液相混合与后续低温烧结(600℃-6 h)制得Li3PO4包覆LiNi0.5Co0.2Mn0.297Al0.003O2材料。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、差示扫描量热法(DSC)等对材料进行分析,结果表明:均匀包覆于材料表面的Li3PO4不改变材料的晶体结构与形貌特征,且能显著提升材料的循环稳定性与热稳定性,LPO-0%与LPO-0.3%循环300次后容量保持率分别为94.4%与97.5%,充电态材料热分解温度分别为274.3和300.9℃。综合性能的提升证明Li3PO4包覆层能抑制活性物质与电解液界面副反应的发生以及材料结构的转变,提高材料的结构稳定性。

Ni0.5 Co0.2 Mn0.297 Al0.003 O2 and LiNi0.5 Co0.2 Mn0.297 Al0.003 O2 material with an average diameter of 9 μm were synthesized by co-precipitation reaction and high temperature sintering(920℃-12 h). Then, LiNi0.5 Co0.2 Mn0.297 Al0.003 O2 material was coated with Li3PO4 by liquid phase mixing and following heat treatment(600 ℃-6 h). The as-prepared samples were characterized by XRD, SEM, TEM and DSC. The results showed that Li3PO4 was coated uniformly on the surface of the material and did not change the crystal structure and morphology characteristics, while it can significantly improve the cyclic stability and thermal stability of the material. The capacity retention of LPO-0% and LPO-0.3% were 94.4% and 97.5%, and the thermal decomposition temperature of charged state were 274.3℃and300.9℃respectively. The improvement of comprehensive properties proves that Li3PO4 coating can inhibit the interfacial reaction between active substance and electrolyte and improve the structural stability of the material.