Ternary polymer network hydrogel electrolyte polyvinyl alcohol/polyacrylamide/chitosan toward zinc ion hybrid supercapacitors

We design a ternary polymer network hydrogel electrolyte polyvinyl alcohol/polyacrylamide/chitosan (PVA/PAM/CS) with zinc chloride (ZnCl 2 ) salt and recycle used hydrogel to prepare carbon for supercapacitors. The mass of acrylamide (AM) and chitosan (CS) are optimized in the synthesize process to obtain good ionic conductivity and mechanical properties, resulting in excellent electrochemical performance. The optimized electrolyte shows tensile strength of 0.41 MPa, ionic conductivity of 32.16 mS cm −1 and breaking elongation of 452 %, respectively. The assembled zinc ion hybrid supercapacitor of commercial activated carbon//zinc foil (YP50//Zn) can achieve maximum energy density of 214.3 Wh kg −1 with capacitance retention of 95.2 % after 28000 cycles. In addition, the supercapacitor device assembled by recycled electrolytes-derived carbon (C-rE-5) can deliver higher energy density of 16.2 Wh kg −1, which is about 2.8 times that of the commercial carbon device (YP50//YP50). This work provides a method to synthesize ternary hydrogel and recycle it for supercapacitors.