Synthesis and electrochemistry of layered 0.6LiNi_(0.5)Mn_(0.5)O_2·xLi_2MnO_3·yLiCoO_2 (x+y=0.4) cathode materials

摘要

Layered cathode materials with the nominal compositions of 0.6LiNi_(0.5)Mn_(0.5)O_2 • xLi_2MnO_3·LiCoO_2 (x+y=0.4) were synthesized by conventional solid-state reaction. Their XRD patterns indicated the formation of solid solutions. The content of Li_2MnO_3 in the solid solutions presented important effects on structure and electrochemistry. The end member, 0.6LiNi_(0.5)Mn_(0.5)O_2 • 0.4LiCoO_2, was isostructural to LiCoO_2, but increasing Li_2MnO_3 content in solid solution materials brought about partial cation ordering. Electrochemical results demonstrated that the increasing of Li_2MnO_3 content in materials improved cycleability. The samples with 0.2 ≤ x ≤ 0.4 delivered the initial discharge capacity of around 190 mA h/g with good cycling performance and are the promising cathode materials in view of capacity and cycleability.