Enhancing the electrochemical performance of a flexible solid-state supercapacitor using a gel polymer electrolyte

Abstract

The development of high-performance polymer electrolytes will be a crucial research target for flexible solid-state supercapacitors (FSSCs). In this study, a flexible gel polymer electrolyte (GPE) was fabricated to enhance flexible solid-state supercapacitor (FSSC) performance and electrochemical stability. 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfony)imide was used as ionic liquid (IL), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as a host polymer with Li1.5Al0.33Sc0.17Ge1.5(PO4)3 (LASGP) serving as ceramic filler to fabricate the GPE films. Scanning electron microscope (SEM) image confirmed that a homogeneous uniform phase with a smooth surface was formed as the ionic liquid was added into the host polymer solution. X-ray diffraction (XRD) patterns show that the PVDF-HFP blend has a semi-crystalline structure while its amorphous nature extended with the increasing amount of IL and LASGP ceramic fillers. The GPE film was used as the electrolyte and separator, due to its high ionic conductivity (7.8×10-2 S cm−1) and excellent thermal stability up to 346 ℃. The FSSC cell with LASGP ceramic filler exhibits a high specific capacitance (115.45 F g−1) with a specific energy density of 27.10 Wh kg−1 at 1 mA. These results indicate that a GPE film with an activated carbon electrode could be a candidate for FSSC applications.