Self‐Regulating the Local Conjugation of Tertiary Aniline toward Highly Stable Polymer Li Metal Batteries

Abstract Pursuing high energy/power density lithium metal batteries (LMBs) with good safety and lifespan is essential for developing next‐generation energy‐storage devices. Nevertheless, the uncontrollable degradation of the electrolyte and the subsequent formation of inferior electrolyte/electrode interfaces present formidable challenges to this endeavor, especially when paring with transition metal oxide cathode. Herein, a fireproof polymeric matrix with a local conjugated structure is constructed by 4,4′‐methylenebis ( N , N ‐diglycidylaniline) (NDA) monomer via in situ polymerization, which promotes the use of ester‐based liquid electrolyte for highly stable LMBs. The conjugated tertiary anilines in this PNDA electrolyte effectively tune the Li + solvation sheath and generate conformal protective layers on the electrode surfaces, resulting in excellent compatibility with both high‐voltage cathodes and Li‐metal anodes. Moreover, the accumulated electron density endows PNDA with a powerful capability to seize and eliminate the corrosive hydrofluoric acid, which strikingly mitigates the irreversible structure transformation of LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC) particles. As a result, the PNDA‐based Li||LiFePO 4 and Li||NMC cells reach excellent electrochemical and safety performance. This study provides a promising strategy for the macromolecular design of electrolytes and emphasizes the importance of “local conjugation” within the polymers for LMBs.