Effective Control of the Solution Environment in Aqueous Zinc-ion Batteries for Promoting (002)-Textured Zinc Growth by a Bio-Electrolyte Additive

Abstract

Aqueous zinc-ion batteries (AZIBs) have garnered considerable interest due to their intrinsic safety features and high energy density. However, challenges such as the growth of Zn dendrites and the prevalence of parasitic reactions during cycling have impeded their broader application. This study introduces Silk Sericin (SS), a multifunctional natural protein, as an electrolyte additive designed to overcome these obstacles. Through a series of detailed experimental validations and theoretical analyses, it is demonstrated that SS molecules, rich in polar functional groups, effectively anchor onto the anode-electrolyte interphase. This anchoring leads to the formation of a stable solid electrolyte interface (SEI) layer while simultaneously modulating the coordination environment of zinc ions through strong interactions with water molecules. The adsorption energies and substantial binding affinity of SS induce a synergistic effect, preferentially orienting zinc ions deposition on the (002) plane, thereby promoting the formation of a flat and compact deposition layer. The modified Zn || Zn cells containing 1% SS exhibit exceptional durability, surpassing 5200 h of operation at 1 mA cm⁻²/1 mAh cm⁻² with highly reversible Zn plating/stripping behavior. Moreover, Zn || VO₂ full cells deliver a high specific capacity of 213 mAh g⁻¹ at 4 A g⁻¹, maintaining robust performances over 3800 cycles. Additionally, Aqueous zinc-ion micro-batteries (AZMBs) based on SS demonstrate superior capacity retention, underscoring their potential for advanced energy storage applications. This research presents a novel electrolyte engineering approach that combines interface control with solution environment optimization, offering an effective strategy to enhance both the reversibility and stability of Zn anodes.