Liquid Metal Synergistic Polyanion Self-adaptable Gel Electrolyte for Stabilizing Dual Electrode/Electrolyte Interfaces in Ultra-Durable Zn-I2 Batteries

The practical applications of aqueous Zn-I 2 batteries are severely hindered by the uncontrolled shutting of polyiodide ions and rampant side reactions. Herein, we integrate coordination-driven monodisperse liquid metal (LM) nanodroplets into a sulfonate-rich polyanionic hydrogel matrix (p(AMPS-AA)) to fabricate a bifunctional gel electrolyte (LM-AP) capable of simultaneously suppressing Zn dendrite growth and polyiodide shuttle effect. Mechanistically, the dynamic hydrogen bond network of the hydrogel and the fluidity of LM nanodroplets synergistically endow the electrolyte with self-adaptive deformation capability, maintaining intimate electrode-electrolyte contact to suppress hydrogen evolution reaction (HER) and dendrite growth. Meanwhile, the electrostatic repulsion of sulfonate ( − SO 3 − ) anionic chains and chemical adsorption of LM nanodroplets jointly block polyiodide shuttling. Consequently, this polyanionic hydrogel electrolyte demonstrates exceptional stability in a symmetrical Zn//Zn cell, maintaining high cycling stability over 3500 h at 0.5 mA cm −2 and 0.5 mAh cm −2 . And the Zn-I 2 batteries with LM-AP electrolyte achieve a high Coulombic efficiency (CE) (∼100%) and exceptionally long cycling stability (85,000 cycles) at a high current density of 20 A g −1 . The high-loading pouch battery maintains a capacity retention rate of 99% after 350 cycles and demonstrated excellent flexibility and safety. This design provides a brand-new idea for solving the problem of multi-interface coupling failure of Zn-I 2 batteries.