Two-in-one structure as both lithium protective layer and electrolyte for safe solid-state lithium-metal battery

Demands for safe and compact electrochemical energy storage inspire hot pursuit of development of solid-state lithium-metal batteries (SSLMBs). However, several challenges, including high reaction activity of lithium metal anode and suboptimal comprehensive performance of solid-state electrolytes, hinder SSLMBs for broad applications. Herein, we propose the ingenious construction and application of polyvinylidene chlorid-based composite (PVDCC) as a two-in-one functional material that simultaneously protects the lithium metal anode from air/water corrosions and acts as solid-state electrolyte. On the basis of standout barrier and fine ion-permeability of PVDC, the as-constructed PVDC-based composite exhibits both excellent high air/water stability and high ionic conductivity in wide temperature range (e.g., 5.02 × 10−4 S cm−1 at 25 °C and 3.92 × 10−4 S cm−1 at 0 °C), thus contributing to remakable electrochemical performances in SSLMB, especially under a low temperature. For instance, at 0 °C, a reversible average discharge capacity of 95 mAh g−1 at 0.3 C with high capacity retention (99%) after 300 cycles can be accomplished. More encouragingly, the PVDCC with two-in-one functionality enables the access of assembling safe SSLMBs in ambient air. This proof-of-concept study offers fresh insights for tailoring the functional materials with both effective lithium protective layer and advanced solid-state electrolyte to facilely achieve high-performance SSLMBs.