PVP-assisted in-situ electrodeposition of zinc anode coatings for interface ion-regulation

Artificial interfacial coatings for Zn anodes in aqueous zinc-ion batteries are critical yet challenging to design, as strong Zn²⁺ adsorption often impedes Zn²⁺ diffusion. Herein, we adapt an interface ion-regulation strategy to address this issue. Given that the total current is carried by both cations and anions, restricting SO₄^2- migration inevitably enhances the relative contribution and effective migration rate of Zn²⁺, thereby preventing the formation of a Zn²⁺ depletion layer at the anode surface. A uniform and stable ZnSn(OH)₆ nanocomposite coating is fabricated via in-situ electrodeposition with the assistance of polyvinylpyrrolidone (PVP), which forms an ion-shielding layer and regulates coating morphology. Nanocomposite coating optimizes the interface H-bond structure, creating a stable microscopic interface. Density functional theory calculations confirm strong SO₄^2- adsorption and high diffusion barrier within ZnSn(OH)₆. By immobilizing SO₄^2-, the coating promotes Zn²⁺ transport, leading to uniform Zn deposition, suppressed side reactions, and reduced polarization. The modified Zn anode achieves exceptional cycling stability exceeding 4000 h. This work presents a simple and low-cost polymer-assisted electrodeposition approach, offering a valuable reference for the design of functional coatings for zinc-ion batteries.