A Lithium‐Inventory‐Aware Interfacial Chemistry Framework for Anode‐Free Lithium–Sulfur Batteries

ABSTRACT Anode‐free lithium–sulfur (AF‐Li–S) batteries eliminate excess lithium by relying on fully lithiated sulfur cathodes, offering high energy density and maximized lithium utilization. However, the absence of a lithium reservoir alters interfacial chemistry, making every parasitic reaction a loss of cyclable lithium. In this lithium‐inventory‐limited system, sulfur redox, Li 2 S activation, electrolyte decomposition, and the evolution of solid–electrolyte and cathode–electrolyte interphases (SEI–CEI) are coupled in a single reaction network. Existing reviews typically treat these processes separately, ignoring their interdependence under anode‐free conditions. This review presents a unified lithium‐inventory‐aware reaction‐network framework that connects these interfacial processes, revealing failure pathways and design constraints not visible in excess‐lithium configurations. Recent advances are reorganized into actionable strategies, including electrolyte and additive design, SEI/CEI engineering, current‐collector surface functionalization, polysulfide regulation, and quasi‐solid‐state confinement. We critically assess advanced operando and multimodal techniques for probing buried interphases, dynamic sulfur chemistry, and lithium redistribution. This review provides a conceptual roadmap for the development of stable, lithium‐efficient AF‐Li–S batteries and outlines general principles for lithium‐inventory‐limited energy storage systems.