Multifunctional polyzwitterion ionic liquid coating for long-lifespan and dendrite-free Zn metal anodes

Aqueous zinc (Zn) metal batteries have received widespread attention due to their high safety and environmental friendliness. However, the uncontrollable growth of dendrites, hydrogen evolution reaction, and corrosion severely limit the practical application of aqueous Zn batteries. Herein, a multifunctional water-blocking polyzwitterion ionic liquid coating poly([2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)-co-tert-butyl acrylate) as the protective layer of the Zn metal anode is proposed to solve these issues. The water-blocking tert-butyl acrylate can prevent water molecules from contacting the Zn metal anode, which plays a key role in inhibiting the hydrogen evolution reaction and corrosion. Meanwhile, zwitterionic ionic liquid moieties are able to tune the solvation environment of the Zn²⁺ at the electrode/electrolyte interface, inducing compact and planar deposition of the Zn metal. With this synergy effect, the assembled Zn//Zn and Zn//Cu cells achieve a long-term stable plating/stripping performance over 2500 h and a high average coulombic efficiency of 98.6% for 1500 cycles. The Zn//MnO₂ and Zn//Mg_0.1V₂O₅·H₂O full cells show negligible capacity decay (0.005%) after 4500 cycles. This work provides a new opportunity to protect Zn anodes by water-blocking polyzwitterion ionic liquid coatings in the aqueous electrolyte.