Microscopic electrochemical–mechanical coupling in layered cathodes under high-voltage and fast-charging conditions

Abstract

The operation of modern society and the advancement of the electric vehicle industry are intrinsically linked to high-performance lithium-ion batteries (LIBs). However, the inherent structural instability of traditional cathode materials under high voltage (high capacity) and rapid charging conditions leads to swift degradation of battery voltage and capacity. This significantly impedes the commercialization of LIBs and contributes to issues such as “range anxiety”. Currently, the failure mechanisms of cathode materials remain highly debated, with most research focusing on material modification and interfacial transport kinetics. Recent studies indicate that the accumulation of nanoscale strain and lattice displacement within cathode materials are critical driving forces behind structural degradation and oxygen loss. Despite their fundamental importance, lattice displacements and nanoscale strain remain among the least understood structural characteristics in battery materials. This review highlights the latest research advancements concerning the electrochemical–mechanical coupling mechanisms and advanced modification strategies of cathode materials. We begin by elucidating the electrochemical–mechanical failure mechanisms of cathode materials, spanning from the atomic to the macroscopic scale, and the interconnections among various failure mechanisms, with particular emphasis on lattice defects and microscopic mechanical anisotropy. Subsequently, we discuss advanced strategies and recent progress in modifying layered oxide cathode materials, which hold promise for furthering the development of the new energy industry. Finally, in the context of a carbon-neutral future and the evolving high-performance electric vehicle industry, we summarize and provide insights into the application prospects and developmental directions of layered oxide cathode materials from perspectives of cost, performance, safety, and environmental friendliness.