Electrochemical Coupled Mechanical Behavior in Single Crystalline Ni-Rich Cathode

Abstract

The long-range electrical vehicles need the stable and safe high energy cathode materials for next generation batteries. High energy Ni-rich cathode plays a key role in advanced Li-ion batteries, but it suffers from moisture sensitivity, side reactions and gas generation, especially when Ni content increases to more than 0.6. Single crystalline Ni-rich cathode is a feasible approach to address the challenges present in its polycrystalline counterpart by reducing phase boundaries and materials surfaces. However, synthesis of high-performance single crystalline Ni-rich cathode is challenging. Owing to low structure stability at high temperature, higher Ni content cathode materials require lower synthesis temperature, in contrast to high temperature and time consuming calcination condition are required to prepare oxide single crystals. Using molten salt approach with sintering agent, single crystalline was successfully synthesized with 3 um average particle size and presents stable electrochemical performance tested in graphite/NMC full cells at realistic conditions. Mechanical behavior was studied on the platform of single crystalline LiNi0.76Mn0.14Co0.1O2. Planar gliding and microcracking were observed and changed along with concentration gradient during lithiation and delithiation.