A Sustainable and Scalable Approach for In Situ Induction of Gradient Nucleation Sites in Biomass-Derived Interface Layers for Ultra-Stable Aqueous Zinc Metal Batteries

Abstract

Aqueous zinc metal batteries are promising candidates for large-grid energy storage due to their safety, cost-effectiveness, and durability. However, challenges like dendrite growth, corrosion, and the hydrogen evolution reaction (HER) on the zinc anode hinder their performance. Herein, we propose a sustainable and scalable approach to form a copper gluconate@carboxymethyl chitosan@kaolin (CuCK) interface layer, inducing gradient nucleation sites via in situ galvanic and galvanostatic processes. The biomass-based CuCK coating features a gradient Cu_xZn_y alloy structure that homogenizes interfacial electric field distribution and enhances electrochemical stability. Furthermore, the incorporated Cu²⁺-loaded kaolin and carboxymethyl chitosan regulate Zn²⁺ flux, accelerate Zn²⁺ desolvation, and suppress HER. The resulting Zn@CuCK anode achieves a high cumulative capacity of 5500 mAh cm^-2 in symmetrical cells, exhibits excellent durability in Zn@CuCK//NaV₃O₈·1.5H₂O full cells across a wide temperature range (-30 to 60 °C), and endows the assembly of pouch cells with high energy density.

Keywords: Aqueous zinc metal batteries; Biomass‐derived interface layers; Electrochemical energy storage and conversion; Gradient nucleation sites; Zn anode.