Bridging Large‐Scale Manufacturability and Nanoscale Interfacial Chemistry in Lithium Metal Solid‐State Batteries

ABSTRACT To address interfacial instability in Li metal all‐solid‐state batteries, protective interlayers have been adopted, yet most rely on coatings or noble metal additives incompatible with scalable manufacturing. Here, we report a nanosized red phosphorus–based interfacial design that enables autogenous chemo‐wetting upon contact with Li, spontaneously forming a Li 3 P‐rich interphase, referred to as the autogenous chemo‐wet interlayer. This reactive layer self‐regulates ionic transport and interfacial adhesion through in situ chemical conversion, producing uniform Li‐ion flux and well‐distributed interfacial current, thereby enabling stable plating and stripping at high current densities and reliable high‐rate solid‐state cycling. The chemo‐wetting mechanism is inherently compatible with roll‐to‐roll transfer printing and enables defect‐free lamination across large‐area electrodes. This coupled mechanical–electrochemical regulation underpins scalable fabrication of solid‐state electrodes, as demonstrated in 6 Ah‐class pouch cells. These discoveries bridge nanoscale interfacial reactivity with macroscale processability and present a step toward practical implementation toward high‐energy, large‐format solid‐state Li metal batteries.