Inspired by plant body frameworks bionics: Fabrication of self-healing polyvinyl alcohol/cellulose nanocrystals composite hydrogels reinforced by polyurethane sponges for flexible supercapacitors

With the booming development of electronic technology, ultra-toughness and self-healing supercapacitors have drawn substantial attentions. In this work, inspired by plant body frameworks, a novel method was proposed to prepare self-healing conductive hydrogels based on self-healing polyurethane sponge (PUS) network. First, a selfhealing PUS based on multiple hydrogen bonding interactions and disulfide bonds was prepared. Subsequently, PUS was combined with polyvinyl alcohol (PVA)/cellulose nanocrystals (CNF) composite hydrogels crosslinked by borate ester bonds and hydrogen bonding interactions to manufacture the sponge network reinforced selfhealing conductive hydrogels. Due to the reinforcement of PUS, the composite hydrogels had excellent mechanical properties, with a tensile strength of 1.81 MPa and a compressive strength of 1.96 MPa. After 400 times of charge-discharge cycles under bending deformation, the supercapacitor could maintain 90.1 % of the original specific capacitance value. Furthermore, the hydrogels could be healed at room temperature due to the hydrogen bonds and reversible borate bonds in PVA/CNF matrix, as well as the disulfide bonds and multiple hydrogen bonds in PUS. The healed supercapacitor could maintain 75.2 % of the original specific capacitance value after 400 times of charge-discharge cycles. Therefore, the as-prepared self-healing and tough conductive hydrogels may have promising prospects in electronic devices.