Rationally Engineering a Quasi-Solid-State Flexible Self-Healing Secondary Battery Using Hydrogel-Based Water-in-Salt Electrolyte and Electrochemically Deposited Electrodes

High safety and low cost are essential for energy-storage systems. Here, an aqueous zinc ion battery composed of a hydrogel-based water-in-salt electrolyte prepared by photoinitiated polymerization of acrylamide in ZnCl₂ solution (named as PZC) and flexible electrodes is developed. The stable performance in Zn||Zn symmetric cells and high Coulombic efficiency of PZC in Zn||Cu asymmetric cells verify dendrite suppression. VO₂ nanobelts coated with polyaniline (PANI) are grown on a carbon cloth (CC). The battery shows a capacity of 221.5 mAh g^-1 after 200 cycles. The batteries present high recovery performance after bending/cutting. After bending of 60°, 90°, and 180°, capacities remain at 240.0, 205.4, and 175.2 mAh g^-1, respectively; while the battery healed from 1, 2, 3, and 4 times of cutting shows 197.5, 174.3, 124.7, and 101.2 mAh g^-1, respectively. Our findings enable the engineering of a quasi-solid-state battery to have good capability for flexible and portable electronics.