Electrochemo‐Mechanical Degradation and Failure of Active Particles in High Energy Density Batteries: A Review

Abstract Failure of the active particles is inherently electrochemo‐mechanics dominated. This review comprehensively examines the electrochemo‐mechanical degradation and failure mechanisms of active particles in high‐energy density lithium‐ion batteries. The study delves into the growth of passivating layers, such as the solid electrolyte interphase (SEI), and their impact on battery performance. It highlights the role of elevated temperatures in accelerating degradation reactions, such as the dissolution of transition metals and the formation of new SEI layers, leading to capacity fade and increased internal resistance. The review also discusses the mechanical degradation of electrode materials, including the fracture of active particles and the impact of stress on electrode performance. Advanced characterization techniques, such as cryogenic scanning transmission electron microscopy and 3D tomography, are explored to provide insights into the structural and chemical evolution of battery materials. By addressing the interplay between chemical, mechanical, and thermal factors, this review aims to provide guidelines for the chemistry development, material selection, structural design as well as recycling of next‐generation batteries with high safety, durability, and high energy density.