Interface-Induced Fast Li⁺ Transport In Mixed Ion-Electronic Conductor

Abstract

Interfacial instability between lithium metal and solid-state electrolytes limits the performance of all-solid-state lithium metal batteries (ASSLBs), leading to parasitic reactions, nonuniform Li⁺ flux, and dendrite growth. Here, we develop a composite interlayer composed of anti-perovskite Li₂OHCl₀.₇₅Br₀.₂₅ (AP) and carbon nanotubes (CNT) to enhance both interfacial stability and ionic transport. The AP-CNT interlayer exhibits enhanced Li⁺ conductivity arsing from interfacial electron transfer from AP to CNT, which generates a built-in electric field that facilitates Li⁺ migration. Lithium symmetric cells incorporating this interlayer achieve a high critical current density of 2.4 mA cm⁻² at 55 °C. This design integrates chemical robustness with coupled ion–electron transport, offering a generalizable strategy for safe, dendrite-free, and high-performance ASSLBs.