Li3OCl/PEGDME synergistically boosts Li+ transport and optimizes interfacial stability of PVDF-based composite solid electrolytes

PEGDME and Li 3 OCl synergistically reduce the crystallinity of PVDF and create additional Li + transport pathways. • The modified PVDF electrolyte exhibits an ionic conductivity of 8.65 × 10 −4 S cm −1 and a Li + transference number of 0.55 at 25 °C. • The assembled LFP cell maintains 80.2% capacity after 500 cycles at 0.5C and 25 °C Owing to superior flexibility and processability, polymer electrolytes have received considerable research attention. Poly(vinylidene fluoride) (PVDF) is a promising electrolyte candidate with high dielectric constant and tunable chain structure, Nevertheless, in lithium metal batteries (LMBs), its high crystallinity results in insufficient Li-ion conductivity, while its inherent porous structure tends to induce uneven Li deposition, thereby causing poor electrolyte-electrode interfacial stability. Herein, a novel PVDF-based composite solid electrolyte is developed by introducing the plasticizer poly(ethylene glycol) dimethyl ether (PEGDME) and Li-rich anti-perovskite Li 3 OCl as fillers. Li 3 OCl can complex with PVDF and induce deprotonation, offering an extra Li + transport pathway, while the synergistic effect between PEGDME and Li 3 OCl effectively reduces PVDF crystallinity and promotes chain mobility. This synergistic design suppresses polymer crystallization, introduces additional Li + conduction channels, and prevents Li dendrites, leading to markedly improved Li + transference number and ionic conductivity, along with a stabilized electrolyte–electrode interface. At 0.5C and 25 °C, the Li | PVDF-LiTFSI-PEGDME-1%Li 3 OCl | LiFePO 4 cell exhibits a capacity retention of 80. 2% after 500 cycles. This research provides an innovative strategy for constructing solid electrolytes with favorable interfacial compatibility and superior ionic conductivity for high-performance LMBs. This study used a solution casting method to prepare a composite polymer solid electrolyte with polyvinylidene fluoride (PVDF) as the polymer, polyethylene glycol dimethyl ether (PEGDME) as the small molecule plasticizer, and lithium rich perovskite resistant Li 3 OCl as the inorganic filler. PEGDME and Li 3 OCl inhibited the crystallization of PVDF, opening up additional channels for Li + transport and significantly improving the efficiency of Li + transport. Meanwhile, the introduction of Li 3 OCl effectively suppressed the growth of lithium dendrites and improved the electrode electrolyte interface problem. After 500 cycles at 0.5C and 25 °C, the capacity retention rate of the assembled LiFePO 4 (LFP) battery reached 80.2%. Download: Download high-res image (182KB) Download: Download full-size image