In-situ Observation of Crack Initiation and Propagation in the NCM811 Cathode Particle

Layered nickel-rich oxide LiNixCoyMn1-x-yO2 (0.6 ≤x<1) is a highly promising positive electrode material.However, the cycling stability of nickel-rich positive electrode materials is limited by particle fracture and a series of side reactions.A comprehensive understanding of particle cracking mechanisms is paramount for material optimization, but crack initiation and propagation have received limited research attention.This paper uses a quasi in-situ SEM observation method and an in-situ optical microscopy observation method to observe crack evolution in real time.The results show rapid cracking behavior under hazardous operating conditions and cracking during cycling under mild conditions.Center cracks and surface cracks are observed during cycling.The observation methods and these insights into the crack behavior offer theoretical guidance for the structural engineering of NCM cathode particles.