Design of delignified wood-based high-performance composite hydrogel electrolyte with double crosslinking of sodium alginate and PAM for flexible supercapacitors

Cellulose-based hydrogel electrolytes have important application prospects in flexible solid-state supercapacitors due to the renewability and high toughness of their raw materials. Currently, cellulose-based hydrogel electrolytes are generally prepared by a bottom-up strategy, which also has poor mechanical properties and low capacitance of the hydrogel electrolytes. These issues need to be further solved. Herein, employed an innovative top-down fabrication approach, utilizing meticulously organized delignified wood as a structural framework, and concurrently integrated polyacrylamide (PAM) and sodium alginate (SA) within this framework, creating a continuous conductive network. Furthermore, multi-walled carbon nanotubes (CNTs) have been introduced as conductive additives. This addition has imparted substantial mechanical robustness and exceptional electrical performance to the wood-based hydrogel. When the concentration of CNTs in the hydrogel precursor solution is 10 mg/ml, the resulting hydrogel electrolyte, denoted as CWH-10, demonstrates a remarkable enhancement in both mechanical strength and electrical conductivity compared to hydrogels modified using conventional techniques. This straightforward fabrication method presents an innovative and promising approach for producing high-strength, bio-based hydrogel electrolytes, with potential applications spanning various fields. •Wood-based hydrogels: Enhanced mechanical strength.•Top-down approach for cellulose scaffold extraction.•The addition process of carbon nanotubes is environmentally friendly.•Notable electrochemical performance in supercapacitors.•Exceptional stability during bending and charge-discharge cycles.