Modified supramolecular carboxylated chitosan as hydrogel electrolyte for quasi-solid-state supercapacitors

Hydrogel-based electrolytes are becoming generally more preferred for electrolyte materials for quasi-solid-state/flexible supercapacitors due to their shape-controlled, high ionic conductivity , no liquid leakage , certain mechanical strength , and flexibility. Here, we develop a modified supramolecular carboxylated chitosan hydrogel electrolyte (CYCTS- g -PAM-Li 2 SO 4 ) synthesized through a free radical graft copolymerization of acrylamide monomers and chemical crosslinking . Compared with PAM-based hydrogel electrolyte (PAM-Li 2 SO 4 ), the modified hydrogel electrolyte of CYCTS- g -PAM-Li 2 SO 4 exhibits better performance including higher ionic conductivity (1.74 × 10 −2  S cm −1 ), better electrolyte absorbability (280%) as well as improved mechanical properties (2.25 MPa). A symmetric quasi-solid-state EDLC (electronic double layer capacitor) by sandwiching activated carbon film electrodes with CYCTS- g- PAM-Li 2 SO 4 as the electrolyte and carbon cloths as the current collectors. Notably, the device shows a wide potential window of 0–1.4 V and delivers a high energy density of 8.7 Wh kg −1 at a power density of 350.3 W kg −1 . Interestingly, two devices connected in series can light an LED lamp . To our knowledge, this is the first time that reported the modified carboxylated chitosan hydrogel electrolyte for quasi-solid-state supercapacitors , which has application potentials for the modified carboxylated chitosan as hydrogel electrolyte for quasi-solid-state, flexible, and portable energy storage devices.