Waste Biopolymer‐Derived Self‐Adjustable Interface for Practical Ah‐Level Aqueous Zinc‐Ion Batteries

ABSTRACT Aqueous zinc‐ion batteries (AZIBs) are promising for grid‐scale energy storage, yet their practical viability is severely hindered by uncontrolled dendrite growth and parasitic reactions of the Zn negative electrode. Herein, inspired by the “waste‐to‐resource” design concept, we develop a sustainable waste biopolymer extracted from municipal sludge as a versatile electrolyte additive for high‐performance Ah‐level pouch cells. Combined experiments and theoretical calculations reveal that the designed biopolymer spontaneously self‐assembles into a self‐adjustable interface with stable and well‐balanced hydrophilic–hydrophobic properties via the competitive adsorption rearrangement of amino acid segments. The self‐adjustable interface fundamentally remodels the electric double layer (EDL) to achieve Zn 2+ local self‐enrichment and a water‐poor interfacial solvation shell, which significantly facilitates Zn 2+ transference and accelerates Zn 2+ desolvation kinetics, thus effectively suppressing interfacial parasitic reactions and dendrite growth. Consequently, the Zn negative electrode achieves high reversibility at 20 mA cm −2 , and the VO 2 ‖Zn full cell sustains remarkable cycling stability for 15 000 cycles. Furthermore, a 2.2 Ah pouch cell demonstrates operational stability for 250 cycles. This work establishes a viable route to develop economic and sustainable electrolyte additives from waste.