Water-Repellent Ionic Liquid Skinny Gels Customized for Aqueous Zn-Ion Battery Anodes

Despite the enormous potential of aqueous zinc (Zn)-ion batteries as a cost-competitive and safer power source, their practical applications have been plagued by the chemical/electrochemical instability of Zn anodes with aqueous electrolytes. Here, ionic liquid (IL) skinny gels are reported as a new class of water-repellent ion-conducting protective layers customized for Zn anodes. The IL skinny gel (thickness ≈500 nm), consisting of hydrophobic IL solvent, Zn salts, and thiol-ene polymer compliant skeleton, prevents the access of water molecules to Zn anodes while allowing Zn²⁺ conduction for redox reactions. The IL-gel-skinned Zn anode enables sustainable Zn plating/stripping cyclability under 90% depth of discharge (DOD_Zn) without suffering from water-triggered interfacial parasitic reactions. Driven by these advantageous effects, a Zn-ion full cell (IL-gel-skinned Zn-anode||aqueous-electrolyte-containing MnO₂ cathode) exhibits high charge/discharge cycling performance (capacity retention ≈95.7% after 600 cycles) that lies beyond those achievable with conventional aqueous Zn-ion battery technologies.