Effects of lithium-active manganese trioxide coating on the structural and electrochemical characteristics of LiNi0.5Co0.2Mn0.3O2 as cathode materials for lithium ion battery

Li2MnO3-coated LiNi0.5Co0.2Mn0.3O2 materials are successfully synthesized by sol-gel method. The effects of various pH values and Li2MnO3 contents on the structural and electrochemical properties of LiNi0.5Co0.2Mn0.3O2 cathode materials are systematically investigated, respectively. Scanning electron microscope, transmission electron microscope and energy dispersive spectrometer confirm that the particles of LiNi0.5Co0.2Mn0.3O2 are completely coated by crystalline Li2MnO3 phase. Electrochemical tests show that suitable Li2MnO3-coated samples exhibit higher rate capacity and better cycling performance than those of the pristine one. This improvement can be attributed to the synergetic contribution from the neutral pH value and appropriate Li2MnO3 amount. The neutral pH environment can protect the core material from damaging during the coating process and is conducive to relieving the rapid moisture uptaking problem of LiNi0.5Co0.2Mn0.3O2. While, suitable Li2MnO3 coating can protect the bulk from directly contacting the electrolyte and offer a fast Li+ diffusion path at the interface of bulk and electrolyte. (C) 2015 Elsevier B.V. All rights reserved.