Engineering a High-Strength and Superior-Electrolyte-Wettability Silk Fibroin-Based Gel Interface Achieving Dendrite-Free Zn Anode.

Abstract

Zn metal anode is confronted with notorious Zn dendrite growth caused by inhomogeneous Zn2+ deposition, rampant dendrite growth, and serious interface side reactions, which significantly hinder their large-scale implication. Interface modification engineering is a powerful strategy to improve the Zn metal anode by regulating Zn2+ deposition behavior, suppressing dendrite formation, and protecting the anode from electrolyte corrosion. Herein, we have designed a high-strength and superior-electrolyte-wettability composite gel protective layer based on silk fibroin (SF) and ionic liquids (ILs) on the Zn anode surface by a straightforward spin-coating strategy. The Zn ion transport kinetics and mechanical properties were further improved by following the incubation process to construct a more well-ordered β-sheet structure. Consequently, the incubated composite gel coating serves as a command station, guiding the Zn ion's preferential growth along the (002) plane, resulting in a smooth and uniform deposition morphology. Driven by these improvements, the zinc anode modified with this composite gel exhibits a remarkably long-term cycling lifespan up to 2200 h at 2 mA cm-2, while also displaying superior rate capability. This study represents a landmark achievement in the realm of electrochemical science, delineating a clear pathway toward the realization of a highly reversible and enduring Zn anode.