Anode-Free All-Solid-State Batteries: Understanding Limitations and Charting a Path to Enhanced Performance

All-solid-state batteries (ASSBs) utilizing sulfide solid-state electrolytes (SSEs) emerge as the most promising platform for next-generation, high-energy-density systems, owing to the exceptional ionic conductivity of SSEs. To maximize energy density, anode-free ASSBs involving direct Li plating and stripping onto the current collector are actively explored. However, the absence of an excess lithium source exacerbates interfacial instability between the SSE and the current collector, impeding commercial viability. This review analyzes the chemical, thermal, electrochemical, and mechanical vulnerabilities of Anode-free sulfide ASSBs. Chemically, atmospheric exposure generates toxic H₂S gas and corrodes the current collector. Furthermore, the narrow electrochemical stability window necessitates the formation of an SEI-like layer composed of decomposition products. Non-uniform electronic and ionic conductivity within this SEI causes localized current density, ultimately promoting Li dendrite growth. Mechanically, non-uniform Li plating-stripping dynamics under high current density accelerate the accumulation of dead Li, while inadequate stack pressure and the significant volume changes during cycling deteriorate cycling stability. To overcome these multifaceted challenges, this study emphasizes the need to develop sophisticated interfacial engineering strategies, alongside active pressure management systems that accommodate volume variations.