Achieving Dendrite-Free Solid-State Lithium-Metal Batteries via In Situ Construction of Li₃P/LiCl Interfacial Layers

Hybrid solid electrolyte (HSE) exhibits potential as a solid electrolyte due to its satisfactory Li⁺ conductivity, superior flexibility, and optimal interface compatibility. However, the inadequate wettability of the Li/HSE interface leads to significant contact impedance, thus fostering the formation of Li dendrites and limiting their practical applicability. Here, a straightforward strategy to enhance the interfacial wettability between Li and HSE and promote the uniform migration of Li⁺ by in situ construction of a multifunctional interface consisting of Li₃P/LiCl (PCl@Li) was created. The Li₃P component acts as a Li⁺ channel, banishing Li⁺ diffusion obstacles within the interface layer, while the electronically insulating LiCl component acts as an electron-blocking shield at the Li/HSE interface, promoting uniform Li⁺ deposition and preventing the formation of Li dendrites. The interface impedance of the symmetric PCl@Li|HSE|PCl@Li battery decreases markedly from 230.2 to 47.4 Ω cm^-2. Additionally, the battery demonstrates superb cycling stability for over 1300 h at 0.1 mA cm^-2 and maintains a minimal overpotential of 32 mV at 30 °C. The PCl@Li|HSE|LiFePO₄ battery shows an initial discharge-specific capacity of 135.6 mA h g^-1 at 1 C, with a notable capacity retention of 87.0% (118.0 mA h g^-1) after 500 cycles. This work provides a new facile strategy for all-solid-state batteries to address interface issues between Li electrodes and HSE.