Kinetic characteristics up to 4.8 V of layered LiNi1/3Co1/3Mn1/3O2 cathode materials for high voltage lithium-ion batteries

Abstract

Understanding the structure properties in deep delithiated states and electrochemical kinetics in the high potential window of LiNi1/3Co1/3Mn1/3O2 (NCM) cathode materials is essential to advance their performance in rechargeable lithium-ion batteries for 5V chemistry. Here we report a layered single-phase NCM showing great structural reversibility and without H3 phase formation when charged up to 4.8V at least for 5 cycles. However, the poor cluster scale conductivity results in inactive material in thick electrode during cycling, approximately 10% (w/w), may corresponding to the reduced capacity respective to thin electrode. The Co3+/Co4+ redox peaks are found clear and stable for cycles, lying between 4.5∼5.0V. That is tightly correlated to the fast Li-ion kinetic, i.e., the electrochemical behaviour of the NCM material is not limited by Li+ diffusion but behaving like in a thin layer. That is very different from previously reports on charge transfer mechanisms of cathode materials for lithium-ion batteries.