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_0.8Mn_0.1Co_0.1O₂ (NMC) particles. As a result, the PNDA-based Li||LiFePO₄ 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.