In Situ Construction of Li3n-Enriched Interface Enabling Ultra-Stable Solid-State Lini0.8co0.1mn0.1o2/Lithium Metal Batteries

Solid polymer electrolytes (SPEs) are considered as the most promising solid-state electrolytes for next-generation lithium (Li) batteries with high safety and electrochemical performance. Whereas, the interfacial side reactions between SPEs and Li metal anode hinder the development of SPEs in solid-state lithium metal batteries (SLMBs). Herein, we propose a g-C3N4 nanosheets (GCNs) reinforced poly(vinylidene fluoride) (PVDF-GCN) composite polymer electrolyte with high ionic conductivity of 6.9×10-4 S cm-1 and low activation energy (0.192 eV). The GCNs are caught by Li metal anode and react with Li metal to in situ produce a Li3N-enriched SEI during cycling process. Such a Li3N-enriched SEI significantly suppresses the continuous side reactions and ensures rapid charge-transfer between PVDF-GCN SPEs and Li metal anode. In addition, the GCNs present quite high adsorption energy for N, N-dimethylformamide molecule to greatly enhance the electrochemical stability of PVDF-GCN composite electrolyte. As a result, the Li symmetrical cell delivers stable cycle over 2200 h. Moreover, the SLMBs using LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode achieve ultra-stable cycling of 1700 times at 1 C and a high discharge capacity of 108 mAh g-1 at 10 C. This work provides novel insights into the construction of a stable SPEs/Li interface for long lifespan SLMBs.