Interface Reversible Electric Field Regulated by Amphoteric Charged Protein-Based Coating Toward High-Rate and Robust Zn Anode.

Metallic interface engineering is a promising strategy to stabilize Zn anode via promoting Zn uniform deposition. However, strong interactions between the coating and Zn and sluggish transport of Zn lead to high anodic polarization. Here, we present a bio-inspired silk fibroin (SF) coating with amphoteric charges to construct an interface reversible electric field, which manipulates the transfer kinetics of Zn and reduces anodic polarization. The alternating positively and negatively charged surface as a build-in driving force can expedite and homogenize Zn flux via the interplay between the charged coating and adsorbed ions, endowing the Zn-SF anode with low polarization voltage and stable plating/stripping. Experimental analyses with theoretical calculations suggest that SF can facilitate the desolvation of [Zn(HO)] and provide nucleation sites for uniform deposition. Consequently, the Zn-SF anode delivers a high-rate performance with low voltage polarization (83 mV at 20 mA cm) and excellent stability (1500 h at 1 mA cm; 500 h at 10 mA cm), realizing exceptional cumulative capacity of 2.5 Ah cm. The full cell coupled with ZnVO·nHO (ZnVO) cathode achieves specific energy of ~ 270.5/150.6 Wh kg (at 0.5/10 A g) with ~ 99.8% Coulombic efficiency and retains ~ 80.3% (at 5.0 A g) after 3000 cycles.