Fast‐Charging Solid‐State Li Batteries: Materials, Strategies, and Prospects

The ability to rapidly charge batteries is crucial for widespread electrification across a number of key sectors, including transportation, grid storage, and portable electronics. Nevertheless, conventional Li‐ion batteries with organic liquid electrolytes face significant technical challenges in achieving rapid charging rates without sacrificing electrochemical efficiency and safety. Solid‐state batteries (SSBs) offer intrinsic stability and safety over their liquid counterparts, which can potentially bring exciting opportunities for fast charging applications. Yet realizing fast‐charging SSBs remains challenging due to several fundamental obstacles, including slow Li⁺ transport within solid electrolytes, sluggish kinetics with the electrodes, poor electrode/electrolyte interfacial contact, as well as the growth of Li dendrites. This article examines fast‐charging SSB challenges through a comprehensive review of materials and strategies for solid electrolytes (ceramics, polymers, and composites), electrodes, and their composites. In particular, methods to enhance ion transport through crystal structure engineering, compositional control, and microstructure optimization are analyzed. The review also addresses interface/interphase chemistry and Li⁺ transport mechanisms, providing insights to guide material design and interface optimization for next‐generation fast‐charging SSBs.