Core–Shell NCM Cathode Particles Mechanical Failure: Particle Cracking and Interfacial Debonding

The core–shell NCM electrode particles are extensively utilized in lithium-ion batteries (LIBs), exhibiting higher electrochemical performance. However, particle cracking and core/shell interfacial debonding seriously reduce the mechanical stability and lifespan of LIBs. Traditional experimental observations ignore the emergence and evolution of particle cracking and interfacial debonding during cycles. Existing simulation studies mainly focus on predicting whether cracking propagation and interfacial debonding will occur, and lack a comprehensive understanding of the formation and influence mechanisms of cracking and debonding. Therefore, we develop a fracture phase-field model coupling Li+ diffusion and mechanical stress to study the particle cracking and interfacial debonding of spherical core–shell NCM electrode particles in a full lithiation-relaxation-delithiation process. The influence mechanisms of geometrical dimensions (particle size and shell thickness) and mechanical properties (shell Young's modulus and interfacial fracture toughness) on particle cracking and interfacial debonding are explored. Focusing on the more serious core/shell interfacial debonding, the phase diagrams are constructed to determine the parameters window to prevent core/shell interfacial failure. This work provides a theoretical foundation for understanding the particle cracking and debonding of core–shell NCM electrode particles and supplies the strategies to inhibit interfacial debonding.