Fused-ring topology orchestrates crystallographic control and polyiodide sequestration for ultra-durable zinc-iodine batteries

Abstract

Aqueous zinc-iodine batteries present a compelling route for sustainable energy storage yet remain hindered by uncontrolled dendritic growth and the parasitic polyiodide shuttle effect. Here, we surmount these challenges by introducing a bifunctional electrolyte modulator, imidazo[1,2-b]pyridazine (IP), characterized by a nitrogen-rich fused-ring aromatic topology, to orchestrate synergistic regulation of both anode and cathode interfaces. At the anode, IP partially displaces water molecules from the Zn2+ solvation sheath and self-assembles into a dense, dynamic adsorption interphase driven by strong π-π stacking interactions. This interfacial restructuring homogenizes ion flux and directs zinc deposition preferentially along the kinetically favorable (100) crystallographic plane, effectively inhibiting dendrite formation. Concurrently at the cathode, the electron-rich nitrogen centers of IP function as Lewis base sites to chemically immobilize soluble polyiodide species. This confinement mechanism mitigates the shuttle effect without compromising intrinsic redox kinetics. Translating this synergistic modulation into electrochemical performance, symmetric cells achieve an ultralong lifespan exceeding 8500 hours at a current density of 1 mA cm-2. Moreover, full Zn||I2 batteries demonstrate robust cyclability, retaining 89.36% of their initial capacity after 2000 cycles. Collectively, this work establishes a dual-site functional coordination strategy that opens a viable avenue for developing highly durable aqueous energy storage systems.