Organohydrogel electrolytes with solvated structure regulation for highly reversible low-temperature zinc metal batteries

Abstract

Aqueous zinc-ion batteries are promising large-scale energy storage systems due to their low cost, high safety and environmental friendliness. However, their operational performance is hindered by two factors: hydrogen (H₂) evolution reaction (HER) that occurs on the Zn anode, and the freezing of the aqueous electrolyte at low temperatures. Here, an organohydrogel electrolyte with H₂O/1,3-dioxolane as a dispersion medium is prepared. Benefitting from the regulation of the Zn²⁺ solvation and anode interfacial chemistry with ether–water bisolvent design, the electrolyte could simultaneously prevent the HER on the Zn electrode and suppress the freezing of the organohydrogel electrolyte below −60 °C. Highly reversible Zn‖Cu asymmetric batteries with a coulombic efficiency (CE) of 99.9% are achieved. The fabricated flexible Zn-ion batteries with the organohydrogel electrolyte showed high electrochemical performance with a capacity of 189 mA h g⁻¹ at 25 °C and high low-temperature tolerance with a capacity of 161 mA h g⁻¹ at −20 °C. Our findings demonstrate an effective strategy for designing organohydrogel electrolytes to achieve stable zinc-ion batteries with extended lifespans at low temperatures.