Differentiated Adsorption Modulation of Microdose Additive Enhances Stability and Kinetics in Zinc-Ion Batteries

Aqueous zinc-ion batteries (AZIBs) offer a promising alternative for large-scale stationary energy storage due to their low cost, high safety, and environmental benignity. However, issues such as dendrite growth, hydrogen evolution, and corrosion at the zinc anode severely limit practical deployment. Here, an adsorption-differential design strategy is proposed, by which low-cost biomass-derived polydextrose (PD) with a microdose of 0.01 m has been identified as an optimal electrolyte additive. Distinctively, PD exhibits zincophilic adsorption on the zinc surface for interfacial reconstruction while remaining Zn²⁺-phobic in the bulk electrolyte, thereby preserving the pristine [Zn(H₂O)₆]²⁺ solvation structure and high ionic conductivity. This dual characteristic simultaneously suppresses side reactions and regulates Zn²⁺ deposition along the (002) plane to inhibit dendrite formation. Consequently, the strategy resolves the long-standing trade-off between cycling stability and reaction kinetics. Using PD-modified ZnSO₄ as electrolyte, Zn||Zn symmetric cells achieve outstanding cycling stability of over 2100 h at 2 mA cm^‒2 and 1350 h at 4 mA cm^‒2. Moreover, Zn||PANI/CNT full cells deliver 81.0% capacity retention after 1300 cycles, markedly outperforming cells containing pure ZnSO₄ electrolyte. This work provides a cost-effective and scalable pathway to improve the electrochemical performance of AZIBs for practical applications.