Novel poly(arylene ether ketone)/poly(ethylene glycol)-grafted poly(arylene ether ketone) composite microporous polymer electrolyte for electrical double-layer capacitors with efficient ionic transport

Abstract

Polymer electrolytes have attracted considerable research interest due to their advantages of shape control, excellent safety, and flexibility. However, the limited use of traditional polymer electrolytes in electric double-layer capacitors due to their unsatisfactory ionic conductivities and poor mechanical properties makes them difficult to operate for long periods of time in large-scale energy storage. Therefore, we fabricated a high-performance microporous electrolyte based on poly(arylene ether ketone) (PAEK)/poly(ethylene glycol)-grafted poly(arylene ether ketone) (PAEK-g-PEG) using a certain amount of carboxylated chitosan with a high electrolyte uptake rate of 322 wt% and a high ionic conductivity of 2 × 10⁻² S cm⁻¹ at room temperature. A symmetric solid-state supercapacitor that uses activated carbon as electrodes and a composite microporous polymer film as the electrolyte shows a high specific capacitance of 134.38 F g⁻¹ at a current density of 0.2 A g⁻¹, while liquid electrolytes demonstrate a specific capacitance of 126.92 F g⁻¹. Energy density of the solid-state supercapacitor was 15.82% higher than that of the liquid supercapacitor at a current density of 5 A g⁻¹. In addition, the solid-state supercapacitor exhibited excellent cycling stability of over 5000 charge/discharge cycles at a current density of 1 A g⁻¹. Furthermore, solid-state supercapacitors display lower self-discharge behavior with an open-circuit potential drop of only 36% within 70 000 s, which is significantly better than that of conventional supercapacitors (52% @ 70 000 s), at a charging current density of 1 mA cm⁻². The satisfactory results indicated that the PAEK/PAEK-g-PEG composite microporous polymer film demonstrates high potential as an electrolyte material in practical applications of solid-state and portable energy storage devices.