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

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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.
Funding Information
  • National Key Research and Development Program of China (2021YFB2400400)

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