Synergistic regulation of solvation structure and interfacial chemistry by LiDFP/Li3OCl for high-performance peo-based composite solid electrolytes

Poly(ethylene oxide) (PEO)-based solid electrolytes are considered one of the most promising solid electrolyte systems due to their favorable flexibility and lithium-salt dissolving capability. However, sluggish Li + transport kinetics caused by high crystallinity at room temperature and poor interfacial stability against high-voltage cathodes severely hinder their practical applications in high-energy-density solid-state lithium batteries. To address these challenges, a synergistic Li 3 OCl/LiDFP regulation strategy is proposed by incorporating lithium-rich antiperovskite Li 3 OCl and LiPO 2 F 2 (LiDFP) into a PEO-based composite electrolyte, enabling simultaneous enhancement of ionic conductivity and interfacial stability. The synergistic effect of Li 3 OCl and LiDFP effectively suppresses PEO crystallization, reducing the crystallinity from 31.13% to 7.79%, while facilitating Li + transport through reconstruction of the local solvation environment. The optimized PLLOC-6%LiDFP electrolyte delivers an ionic conductivity of 1.80 × 10 –5 S cm –1 . The corresponding Li∥Li symmetric cell exhibits stable cycling for over 850 h at 0.2 mA cm –2 and achieves a critical current density of 0.45 mA cm –2 . Furthermore, the Li∥NCM811 cell maintains a capacity retention of 78.68% after 200 cycles at 1 C and 25 °C. Interfacial characterization reveals the in situ formation of robust interphases enriched with LiF, Li 3 N, Li 3 PO 4 , and Li x POF y species during cycling, which effectively suppress parasitic interfacial reactions and promote Li + transport. This work provides an effective strategy for simultaneously improving ionic transport and high-voltage interfacial stability in PEO-based composite solid electrolytes. Download: Download high-res image (284KB) Download: Download full-size image