High voltage, toughness and improved interfacial ion deposition through a dual-crosslinked and self-healable hydrogel electrolyte for green zinc-ion batteries

•CMC/SA-Zn2+ gel electrolyte is designed for manipulating interfacial chemistry.•CMC/SA-Zn2+ inhibits Zn-related issues and shows improved durability.•The decomposition voltage of the CMC/SA-Zn2+ is higher than 2.4 V.•The self-healing Zn-MnO2batteriesdemonstrate exceptional dynamic stability.•The pathway excludes the petroleum-based polymers and chemical crosslinkers. The inconsistent zinc stripping/deposition leading to low durability of zinc anodes is a fundamental obstacle for the practical application of zinc-based aqueous batteries. Hence, the self-healing capability of flexible batteries is crucial for enhancing their durability and dependability during routine operation, as it allows them to withstand various deformations. Through composite strengthening and dynamic coordination complexation, we have developed a dual-crosslinked and natural polymer-based self-healing hydrogel electrolyte (sodium carboxymethyl cellulose/sodium alginate-Zn2+, denoted as CMC/SA-Zn2+) for flexible Zn-MnO2 batteries. The metal coordination interactions of carboxyl groups with Zn2+ as the dynamic motif are contributed to excellent mechanical and electrochemical properties, as well as fast self-healing ability for the CMC/SA-Zn2+ hydrogel electrolyte. Moreover, the improved compatibility of the electrode and electrolyte at their interfaces results in considerably more meticulous Zn deposition. Subsequently, a reversible plating/stripping performance is observed in a symmetric cell for a duration of 2000 h. After applying this self-healing and tough electrolyte to the flexible Zn-MnO2 battery, it is constructed with a high capacity of 218 mAh/g and a high coulombic efficiency close to 100 %. Additionally, the flexible batteries exhibit exceptional resilience and can recover their electrochemical performance even after enduring multiple mechanical damages, highlighting their potential use in wearable electronics.