Modulating Interfacial Ion Transport with an Aluminum Alginate Surface Layer for Stable Zinc Anodes

Metallic zinc is a promising anode candidate for high-safety, low-cost, and large-scale energy storage systems. However, its practical application is severely impeded by unstable electrode/electrolyte interfaces, including zinc dendrite growth, corrosion, passivation, and hydrogen evolution reactions. Herein, we designed a stable artificial interfacial layer of aluminum alginate (AA@Zn) on the zinc anode surface through the coordination effect between the negatively charged carboxyl groups in sodium alginate (SA) and Al³⁺ ions. The carboxyl and hydroxyl functional groups in the AA coating can form a stable solid-state hydrogen-bonding network with water molecules, thereby suppressing the hydrogen evolution reaction (HER) and corrosion behavior. The electrostatic repulsion between carboxylate groups and sulfate ions (SO₄^2-) in the electrolyte significantly reduces the generation of parasitic byproducts on the zinc anode surface. Furthermore, the AA coating acts as a favorable nucleation site to lower the Zn deposition energy barrier and promote uniform Zn deposition with more homogeneous nucleation. In addition, the AA coating exhibits favorable mechanical robustness and electrolyte wettability and inhibits the growth of zinc dendrites through the deposition of uniform zinc ions with uniform electric field distribution, thus achieving long-term cycling stability of the electrode interface chemistry. At a current density of 1 mA cm^-2, a symmetric battery assembled with AA@Zn electrodes demonstrated a long cycle life of 3000 h. This research is expected to provide a technical basis for designing functional interfaces of metal anodes of AZIBs.