Polypyrrole as Dissociation Promoter and Interface Stabilizer of Solid Polymer Electrolytes for Solid‐State Li Metal Batteries

Abstract

Advanced solid polymer electrolytes (SPEs) are indispensable for enabling durable, safe, and high‐energy‐density solid‐state lithium metal batteries (SSLMBs). However, the concurrent optimization of lithium‐salt dissociation, Li + transport, and lithium‐metal interfacial chemistry remains a challenge over decades. In this study, a PPy‐regulated solid polymer electrolyte (PPyPL) featuring chemically differentiated coordination sites is developed to reconstruct ion‐solvation chemistry through site‐selective Li + /anion coordination. The resulting coordination architecture affords differentiated molecular interactions in which pyrrolic nitrogen sites preferentially coordinate Li + , whereas hydrogen sites along the PPy backbone interact with bis(trifluoromethanesulfonyl)imide (TFSI − ) anions, thereby simultaneously promoting lithium‐salt dissociation, accelerating Li + transport, and directing LiF/Li 3 N‐rich interphase formation. Benefiting from the synergistic regulation of ion‐solvation chemistry and interfacial evolution, PPyPL achieves an ionic conductivity of 0.76 mS cm −1 at room temperature (25°C), a Li + transference number of 0.65, and ultralong Li plating/stripping stability over 8000 h. It further enables outstanding rate capability and durable cycling in both Li||LiFePO 4 (LFP) and Li||LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) solid‐state full cells. This work provides a new strategy for regulating Li + /anion coordination in advanced SPEs toward durable SSLMBs.