High-current-density solid-state lithium metal batteries through interface engineering

The rapid evolution of solid-state battery technology has emphasised the importance of interface engineering to overcome key limitations, including poor interfacial contact, lithium dendrite formation, and unstable electrode-electrolyte interfaces. This article provides a critical overview of recent advances in interfacial modification strategies tailored to various solid-state electrolytes, including oxide-, sulphide-, halide-, and polymer-based systems. Emphasis is placed on integrating ultrathin coatings, advanced deposition techniques, and in situ interfacial formation to enhance electrochemical stability, suppress lithium dendrites, and enable high-current-density operation. By systematically categorising techniques such as atomic layer deposition, pulsed laser deposition, chemical vapour deposition, and wet-chemical solution-based methods, we evaluate their effectiveness at stabilising the Li-metal interface for application in all-solid-state metal batteries. This review aims to serve as a roadmap for rational interface design, material selection, and fabrication routes, and to assess their impact on battery performance and cycling life.