A tailored dual-layer electronic shielding interface enables highly stable and dendrite-free solid-state lithium metal batteries

All-solid-state lithium metal batteries (ASSLMBs) have emerged as promising energy storage devices due to their high energy density and enhanced safety features. However, challenges related to Li/electrolyte interface stability and ion transport efficiency hinder the practical implementation of sulfide-based ASSLMBs. In this study, we tailored the Li anode interface from the conventional mosaic structure to dual-layer gradient structure through a simple conversion reaction with an organic fluoride. The dual-layer multifunctional interface consists of a highly flexible and wettable upper layer enriched with organic LiBASF3 compounds and an LiF-rich lower layer with high interfacial energy. Eventually, the glittering integration of targeted surface smoothness, excellent interfacial wettability, and high interfacial energy is verified by experimental and theoretical calculation results. The insulating property of the dual-layer interface can impede electronic tunneling and minimize current leakage into the sulfide solid-state electrolytes. Ultimately, the implementation of interface engineering has shown significant improvements in enhancing the critical current density (CCD, 1.9 mA cm−2) of symmetric batteries, as well as enhancing the long-term cycling stability and capacity retention rate of the FeS2 and LiCoO2 cathodes based full cells.