Kinetic characteristics up to 4.8 V of layered LiNi1/3Co1/3Mn1/3O2 cathode materials for high voltage lithium-ion batteries. (10th February 2017) - Zhang, Xianhui
Graphical abstract: Stable dual-redox pairs and thin-layer liked kinetics benefit NCM cathode for 5 V lithium chemistry. Highlights: NCM conserves high structural reversibility without phase changes up to 4.8 V. NCM shows clear and stable Co 3+ /Co 4+ couples between 4.5–5.0 V for cycles. Li + diffuses like in a thin layer in deep delithiated states. The poor inter-cluster conductivity may result in a 10% capacity lose in electrodes. Abstract: Understanding the structure properties in deep delithiated states and electrochemical kinetics in the high potential window of LiNi1/3 Co1/3 Mn1/3 O2 (NCM) cathode materials is essential to advance their performance in rechargeable lithium-ion batteries for 5 V chemistry. Here we report a layered single-phase NCM showing great structural reversibility and without H3 phase formation when charged up to 4.8 V 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 Co 3+ /Co 4+ redox peaks are found clear and stable for cycles, lying between 4.5 ∼ 5.0 V. 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.