Li_3PO_4包覆LiMn_2O_4正极材料的结构表征和电化学性能

采用共沉淀法在尖晶石LiMn2O4颗粒表面包覆Li3PO4.XRD、SEM研究结果表明,包覆后的材料仍为尖晶石结构,粒径均匀.电化学性能测试表明,Li3PO4包覆层的存在,减少了正极材料与电解液的直接接触,抑制了高温下电解液对LiMn2O4材料的侵蚀,从而有效改善了高温下材料的循环性能.在40℃时,包覆样品的比容量衰减率都低于未包覆样品,其中包覆1%Li3PO4的样品的初始比容量为110.4mAh/g,50次循环后比容量为84.1mAh/g.

Structure Characterization and Electrochemical Properties of LiMn2O4 Coated with Li3PO4

Spinel LiMn2O4 was modified using surface coating with Li3PO4 using co-precipitation method. The XRD and SEM analysis showed that the coated material had the appearance of full crystal, it’s structure was still the cubic spinel, and the grain distribution was uniform. The electrochemical analysis of these samples showed that the layer of Li3PO4 can reduce the direct contact of LiMn2O4 with electrolyte, avoiding corrosion from the electrolyte and enhancing the electrochemical performance of the positive active materials for lithium ion batteries at high temperature. At 40℃, the losing ratios of specific discharge capacity of all the coated-samples were lower than that of pure LiMn2O4. The initial capacity of 1% Li3PO4 coated spinel was 110.4mAh/g, and after 50 cycles, the specific discharge capacity was 84.1mAh/g at 40℃.