Electron-Initiated Self-Growth In Situ Hydrogel Electrolyte with Gradient Protection Interface Enables Stable Zinc Metal Batteries

In situ gelation technology holds great promise for high-performance and scalable energy storage systems, but the dynamic analysis of in situ polymerization kinetics and interface evolution mechanism has not yet been explored in aqueous zinc metal batteries (AZMBs). Herein, an electron-initiated self-growth in situ hydrogel electrolyte was developed, realizing the controllable growth of a vertically oriented gel electrolyte through interfacial chemical reconstruction. The formation mechanism has been explored in detail in which the axially aligned polymer chains formed by the self-growing behavior of the hydrogel promote the precise alignment of internal zwitterionic functional groups, creating unique zinc ion transport channels. Moreover, the preadsorption effect of in situ hydrogel electrolyte effectively suppresses excessive disordered decomposition of electrolyte salts, resulting in a robust and compatible electrode-electrolyte interface with a gradient protection layer of Zn anode. As a result, the Zn||Zn symmetric battery with in situ hydrogel electrolyte exhibits excellent cycle stability for more than 3000 h. The full battery can work stably under the low current density, and shows no significant capacity decay after 1000 cycles with 382 mAh g^-1. Stable operation of a pouch battery with a high mass loading confirms the practicality of this in situ gel polymer electrolyte (GPE) strategy in AZMBs.