Natural Biomass Hydrogel Based on Cotton Fibers/PVA for Acid Supercapacitors

A gel polymer electrolyte (GPE) is prepared for enhancing electrochemical performances of supercapacitors (SCs), using a cotton and PVA composite membrane as the polymer matrix and 1 M H2SO4 solution as the electrolyte. The synthesized cotton/poly(vinyl alcohol) (PVA)-based membrane with a weight ratio of 8:5 (C5) shows a high tensile strength of 3.55 MPa and an electrolyte uptake of 901.45 wt %, and the SC based on the corresponding membrane (G5) delivers the best specific capacitance: it attains 106 F g–1 at 1.0 A g–1 and maintains 106% of the initial capacitance after 10 000 cycles. In addition, three planar SCs in series assembled with G5 exhibit superb electrochemical performances and flexibility as G5 can be bent to 180° without damage, maintaining superior electrochemical performance. Therefore, G5 is a possible candidate for flexible SCs with outstanding performance.