Ultrahigh salt content enables the nonflammable PVDF-based solid electrolyte with high ionic conductivity

Abstract

Solid-state polymer electrolytes (SSPEs) in combination with an ultrahigh content of lithium salt would result in the poor membrane-forming property and mechanical strength of electrolyte member. To address these issues, herein, we construct glass fibre (GF) supported poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) electrolyte membrane (GF-PVHF) with the mass ratio of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to PVDF-HFP ranging from 1.0 to 3.4. When the GF-PVHF electrolyte membrane with 2.8 mass ratio shows the high room temperature ionic conductivity of 8.92 × 10⁻⁴ Scm⁻¹, and presents the good flexibility and non-flammability due to the synergistic action between GF and PVDF-HFP. Both the assembled LiFePO₄/Li and LiNi_0.6Co_0.2Mn_0.2O₂/Li batteries exhibit excellent cycling stability, with capacity retention of 93.9% for LiFePO₄/Li after 300 cycles at room temperature and 88.9% for LiNi_0.6Co_0.2Mn_0.2O₂/Li after 100 cycles at room temperature. This work provides a strategy of designing SSPEs with ultrahigh salt concentration over 70%.