Advancements, Failure Mechanisms, and Modification Strategies in Solid‐State Battery Research: Paving the Way for Next‐Generation Energy Storage

ABSTRACT The solid‐state batteries are expected to be the next‐generation energy storage technology to replace traditional organic liquid lithium‐ion batteries because of their high energy density and safety. As the most critical component, solid‐state electrolytes largely lead the future battery development and an ideal electrolyte must exhibit high ionic conductivity, wide electrochemical window, and good compatibility with electrodes. Despite their inherent advantages, it still faces a great diversity of challenges. The stability of the solid electrolyte at high temperatures still requires further improvement to ensure optimal battery performance under elevated temperatures. The ionic conductivity of the solid electrolyte is relatively low, leading to sluggish charge and discharge rates as well as rapid capacity degradation. Insufficient contact between solid interfaces can increase charge impedance and adversely impact battery performance. In this review, we reviewed the solid‐state batteries on recent developments, followed by a detailed analysis of the underlying failure mechanisms that currently hinder their performance. Especially, it emphasized the intrinsic coupling among interfacial thermodynamics, reaction–transport competition, and electrochemical–mechanical degradation. In response to these challenges, a series of modification strategies based on application‐oriented design principles were highlighted to offer a foundational framework to support solid‐state batteries in next‐generation energy storage devices.