Cathode‐Dependent Electrochemical–Mechanical Coupling Governing Edge Lithium Plating and Interfacial Void Heterogeneity of Lithium‐Ion Batteries

ABSTRACT Lithium plating is a severe safety hazard in lithium‐ion batteries and is traditionally regarded as an anode‐dominated failure. Here, we unveil a cathode‐dependent origin of edge lithium plating, accounting for the higher susceptibility of LiFePO ₄ (LFP) cells. We demonstrate that asynchronous lattice‐volume and thickness evolution between LFP and graphite electrodes induces multistage expansion–contraction during cycling. Coupled with the intrinsic center–edge disparity in mechanical constraints of pouch cells, this behavior progressively amplifies mechanical heterogeneity, driving preferential lithium plating at low‐pressure edge regions in LFP||graphite pouch cells. This electrochemical–mechanical origin is supported by spatially resolved operando cell thickness measurements, highly heterogeneous interfacial voids within the lithium plating layer, and experimentally informed finite‐element simulations. Moreover, a mechanically optimized and uniform external pressure regulation strategy effectively suppresses edge lithium plating, enabling over 90% capacity retention after 3500 cycles at 1C. This work identifies a cathode‐dependent degradation pathway and provides a practical framework for electrochemical–mechanical coupling‐informed battery design.