Stable Zn Metal Anode Enabled by a Zincophilic Polyanionic Hydrogel Layer

The practical application of Zn metal anode for aqueous batteries is greatly restricted by the catastrophic dendrites growth, intricate hydrogen evolution and parasitic surface passivation. Herein, a polyanionic hydrogel film is introduced as a protective layer on Zn anode with the assistance of saline coupling agent (denote as Zn-SHn). The hydrogel framework with zincophilic -SO₃^– functional group uniformizes the zinc ions flux and transport, and such hydrogel layer chemically bonded on Zn surface obviously suppresses the dendrites formation by guiding the 3D Zn accumulation. Consequently, very stable and reversible Zn stripping and 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 capacity retention around 67 % over 4000 cycles at 10 A g^–1. The presented polyanionic hydrogel film protection strategy paves a new way for future Zn anode design and safe aqueous batteries construction.