Deciphering interfacial challenges for Li metal anodes across liquid and solid state batteries

The development of high-energy-density lithium metal batteries (LMBs) is central to the advancement of next-generation energy storage. In this review, the comprehensive landscape of the lithium metal anode is evaluated, spanning the transition from traditional liquid electrolyte systems to solid-state and anode-free architectures. Fundamental limitations, including dendrite initiation and solid electrolyte interphase (SEI) formation, are analyzed through various theoretical models. Significant focus is placed on stabilization strategies within liquid electrolytes, where the engineering of artificial SEIs through vapor and liquid-phase techniques is combined with the structural design of three-dimensional current collectors. Furthermore, the interfacial challenges unique to solid-state electrolytes, specifically garnet, sulfide, and halide-based systems, are addressed, highlighting the deployment of alloy anodes and interfacial modification layers to mitigate chemo-mechanical failure. The critical role of advanced characterization techniques, such as cryo-electron microscopy, synchrotron X-ray absorption, and solid-state nuclear magnetic resonance, is discussed in the context of resolving complex interfacial phenomena. Finally, practical lab-scale testing protocols are emphasized to ensure the reproducibility and commercial relevance of LMBs research. This work provides a multi-scale perspective on the fundamental understanding and engineering design required to realize stable, high-performance LMBs systems.