In situ construction of a fast-ion-conductive anode for seawater-based zinc-ion batteries

The practical promotion of zinc-based seawater batteries is hindered by the thermodynamic instability and kinetic irreversibility of zinc anodes, which cause severe dendrite growth and side reactions. Traditional inorganic coatings for zinc anodes often suffer from poor interfacial adhesion with the substrate, leading to delamination during cycling. Furthermore, they offer insufficient protection against chloride-induced corrosion in seawater electrolytes. To address these issues, we develop a wet-chemistry method to in situ construct a hydrophilic silica layer (OH-SiO₂) chemically bonded to zinc substrate via Zn-O-Si bonds. This artificial interface facilitates the capture and desolvation of hydrated Zn2+, repels corrosive chloride ions, and provides abundant channels for rapid zinc ions transport. As a result, zinc deposits uniformly underneath the protective layer. When tested in the seawater electrolyte, the OH-SiO₂-Zn anode demonstrates exceptional stability over 2300 h during the symmetric cell test. Full cell which adopts OH-SiO₂-Zn and α-MnO₂ cathode also exhibits remarkable cycling performance coupled with superb rate capability. This work provides an effective and extensible method for constructing outstanding zinc anodes and advances the use of low-cost seawater electrolytes in zinc-ion batteries.