A hydrophobic and zincophilic protective layer for highly reversible Zn metal anodes

The practical applications of aqueous zinc-ion batteries (ZIBs) suffered from severe dendrite growth, Zn corrosion, and hydrogen evolution. Herein, a hydrophobic and zincophilic coating composed of low surface energy polydimethylsiloxane (PDMS) and rough Ag particles was constructed to regulate the H₂O adsorption energy on Zn metal anode. Hydrophobic PDMS can suppress hydrogen production and parasitic side reactions by isolating electrolyte from contacting Zn metal, while Ag particles with high zinc affinity can effectively facilitate uniform Zn plating/stripping in the porous structure, inhibiting Zn dendrite formation. Meanwhile, the experiments and theoretical calculations demonstrated that the PDMS@Ag@Zn exhibited larger water contact, weaker H₂O adsorption, and higher Zn²⁺ affinity than Zn metal. Therefore, the symmetric cells using PDMS@Ag@Zn electrodes showed durable cycling stability over 3000 h with an ultralow overpotential of 17.8 mV at current density/areal capacity of 0.25 mA cm⁻²/0.25 mAh cm⁻². Besides, the full cell paired with Na₂V₆O₁₆·3H₂O cathode delivered a high capacity of 372 mAh g⁻¹ at 0.1 A g⁻¹ and displayed superior cycling performance with 93.3 % capacity retention after 2700 cycles at 1.0 A g⁻¹. This work provides a universal route on controllable H₂O adsorption via special wettability regulation on Zn metal towards high-performance aqueous metal anode-based batteries.