Addressing Solid‐State Battery Mechanics: The Critical Step Toward Commercial Viability

All‐solid‐state lithium batteries (ASSLBs) are regarded as the most promising next‐generation battery technology, offering both higher energy density and enhanced safety. However, the electrochemical performance of ASSLBs is governed not only by the intrinsic kinetic behavior and electrochemical stability of electrode materials, but also by a range of mechanical behaviors that have been largely overlooked. This is particularly critical for high‐capacity anode materials (Li, Si, Al, and Sn) that inevitably undergo large volume changes during cycling, the resulting evolution of mechanical stress and strain plays a decisive role in battery lifespan and reliability, especially in pouch cells with large‐area electrodes and thin electrolyte films. This Perspective provides an overview of the key mechanical challenges in ASSLBs, including stack pressure, plastic deformation, creep behavior, mechanical crosstalk, and operation‐dependent stress evolution. We further analyze how these mechanical factors fundamentally affect electrochemical performance across multiple scales and operating conditions. Furthermore, we systematically evaluate emerging strategies for mitigating mechanical stress and engineering interfaces that show promise for enhancing electrochemical performance and extending the cycle life of ASSLBs. By highlighting the crucial intersection between mechanical and electrochemical processes, this Perspective provides design principles and research directions to accelerate the development of reliable ASSLBs.