High energy density, flexible, low temperature resistant and self-healing Zn-ion hybrid capacitors based on hydrogel electrolyte

Zn-ion hybrid capacitors (ZIHCs) are new types of energy storage system with enormous application prospect. However, the limited energy density and poor durability hinder their application. Herein, we design a hydrogel electrolyte based on Fe3+ ionic cross-linked anionic copolymer formed by AMPSZn (2-acrylamido-2-methyl-1-propane sulfonate zinc) and AAZn (zinc acrylate) in the presence of ZnCl2. The prepared ZIHCs have excellent electrochemical performance, which deliver a battery-level energy density of 205.3 Wh kg−1 at a power density of 1.01 kW kg−1 and retain 81.2% of initial capacitance after 1000 cycles. Importantly, based on hydrogel electrolyte, the prepared ZIHCs also have excellent durability which still work under twisted or bent as well as self-heal after being wholly cut. The ZIHCs are also capable at low temperature showing excellent reliability. In this work, high energy density, flexible, low temperature resistant and self-healing Zn-ion hybrid capacitors were prepared by designing hydrogel electrolyte which provides a new strategy for high performance and reliable ZIHCs.