Stable Zinc Anodes Enabled by a Zincophilic Polyanionic Hydrogel Layer

The practical application of the Zn-metal anode for aqueous batteries is greatly restricted by catastrophic dendrite growth, intricate hydrogen evolution, and parasitic surface passivation. Herein, a polyanionic hydrogel film is introduced as a protective layer on the Zn anode with the assistance of a silane coupling agent (denoted as Zn–SHn). The hydrogel framework with zincophilic –SO₃⁻ functional groups uniformizes the zinc ions flux and transport. Furthermore, such a hydrogel layer chemically bonded on the Zn surface possesses an anti-catalysis effect, which effectively suppresses both the hydrogen evolution reaction and formation of Zn dendrites. As a result, stable and reversible Zn stripping/plating at various currents and capacities is achieved. A full cell by pairing the Zn–SHn anode with a NaV₃O₈·1.5 H₂O cathode shows a capacity of around 176 mAh g⁻¹ with a retention around 67% over 4000 cycles at 10 A g⁻¹. This polyanionic hydrogel film protection strategy paves a new way for future Zn-anode design and safe aqueous batteries construction.