An Acid‐Resistant Gel Polymer Electrolyte Based on Lignocellulose of Natural Biomass for Supercapacitors

A novel acid‐resistant gel polymer electrolyte (GPE) is fabricated for improving the electrochemical performance of supercapacitors (SCs) using lignocellulose (LC) membrane as polymer matrices and H 2 SO 4 solution as both plasticizer and conductive ions, in which the LC membrane with a stress of 10.1 MPa and an electrolyte uptake of 1300% is prepared from LC biomass. The prepared GPE (LC‐H 2 SO 4 ) has no obvious change after immersion in 3 m H 2 SO 4 solution for 30 days. The SC assembled with LC‐H 2 SO 4 containing 1 m H 2 SO 4 and activated carbon electrodes shows a rate capability of ≈90% retention of initial capacitance when the current density increases from 0.5 to 5 A g −1 and long cycling life of 20 000 cycles with 115% capacitance retention, which is attributed to hemicellulose dissolving in the electrolyte improving interfacial compatibility, and these oxygen‐containing functional groups provide partial faradic pseudocapacitance. Furthermore, the flat SC assembled with LC‐H 2 SO 4 containing 3 m H 2 SO 4 demonstrates better electrochemical performance than that of flat SCs based on LC‐H 2 SO 4 containing 0.5 and 1 m H 2 SO 4 . The assembled flat SC can be bent to 180° without affecting its electrochemical performance. Hence, LC‐H 2 SO 4 containing higher H 2 SO 4 concentration is a candidate for assembly flexible SCs with excellent electrochemical performance.