Interfacial Engineering in Solid-State Lithium Metal Batteries: Degradation Mechanisms and Dynamic Regulation Strategies

Solid-state lithium metal batteries (SLMBs), recognized as next-generation energy storage systems for their high energy density and intrinsic safety, face commercialization challenges stemming from interfacial instability, lithium dendrite proliferation, and rapid capacity degradation in anode-free configurations. This review analyzes the underlying mechanisms of performance deterioration in SLMBs: (1) the highly reactive lithium metal engages in chemical or electrochemical side reactions with the solid-state electrolyte (SE), leading to a continuous increase in interfacial impedance; (2) Volume fluctuations during lithium deposition/stripping trigger mechanical contact failure; (3) Irreversible lithium consumption in anode-free systems creates a self-amplifying degradation cycle. In order to solve these issues, we focuses on three major modification strategies: (1) Three-dimensional porous current collectors for homogeneous lithium-ion flux regulation and dendrite suppression; (2) Constructing a gradient artificial interfacial layer to inhibit electron leakage and promote ion transport; (3) Developing dynamic self-adaptive interfacial systems that utilize in situ alloying reactions to achieve interface self-healing. In addition, the core contradictions in anode-free systems are furtherly analyzed. Furthermore, we emphasize the critical role of synergistic optimization between current collectors and interfacial layers in enhancing lithium deposition reversibility. By elucidating the fundamental principles and interdependencies of existing modification approaches, this review provides theoretical guidance and innovative design principles for developing high-performance SLMBs with extended cycle life and commercial viability.