Electrode Separators Derived from Polytetrafluoroethylene/Polyvinylpyrrolidone Electrospun Nanofibers for Supercapacitors in Ionic Liquid Electrolytes

Separators have garnered increasing attention for enhancing the performance of supercapacitors, particularly in terms of high safety and a long cycle life. However, commercial polyolefin separators suffer from rapid capacity degradation and safety concerns due to poor electrolyte wettability and low thermal stability. Polytetrafluoroethylene (PTFE) offers excellent chemical resistance, which is beneficial for separator stability, but its low solvent solubility limits its broader electrochemical application. To overcome this, PTFE can be incorporated via electrospinning with hydrophilic polymers. In this approach, PTFE/polyvinylpyrrolidone (PVP)-derived nanofibers are fabricated by electrospinning an emulsion of PTFE in dilute PVP aqueous solution, followed by thermal treatment at varying sintering temperatures to remove the PVP component from the PTFE/PVP electrospun nanofibers. Leveraging the good wettability of PVP and the excellent thermal stability of PTFE, the resulting PTFE-derived electrospun separators exhibit high thermal/chemical resistance alongside excellent wettability. The relationship between electrochemical performance and structural features of supercapacitors using those PTFE-derived nanofiber separators in ionic liquid electrolytes was systematically investigated. Notably, these separators demonstrate superior electrochemical performance. Overall, this study presents a promising strategy for fabricating PTFE-based nanofibers for advanced electrode separators.