Cross-Linked Poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-co-HFP) Gel Polymer Electrolyte for Flexible Li-Ion Battery Integrated with Organic Light Emitting Diode (OLED)

Abstract

Here, we fabricate poly(vinylidene fluoride-<i>co</i>-hexafluoropropene) (PVDF-<i>co</i>-HFP) by electrospinning for a gel polymer electrolyte (GPE) for use in flexible Li-ion batteries (LIBs). As a solvent, we use <i>N</i>-methyl-2-pyrrolidone (NMP), which helps produce the cross-linked morphology of PVDF-<i>co</i>-HFP separator, owing to its low volatility. The cross-linked PVDF-<i>co</i>-HFP separator shows an uptake rate higher than that of a commercialized polypropylene (PP) separator. Moreover, the PVDF-<i>co</i>-HFP separator shows an ionic conductivity of 2.3 × 10^-3 S/cm at room temperature, comparable with previously reported values. An LIB full-cell assembled with the PVDF-<i>co</i>-HFP-based GPE shows capacities higher than its counterpart with the commercialized PP separator, confirming that the cross-linked PVDF-<i>co</i>-HFP separator provides highly efficient ionic conducting pathways. In addition, we integrate a flexible LIB cell using the PVDF-<i>co</i>-HFP GPE with a flexible organic light emitting diode (OLED), demonstrating a fully flexible unit of LIB and OLED.