Itaconic acid additives reconstruct the solvation structure and stabilize the anode interface of aqueous zinc-ion...

Aqueous zinc-ion batteries (AZIBs) possess high inherent safety, high ionic conductivity, low cost and environmental friendliness, showing promise for grid-level energy storage. However, zinc anode dendrite growth and interface side effect restrict their practical application. In this work, itaconic acid (IA) is proposed as a multifunctional electrolyte additive to solve the above challenges because it can ionize in aqueous solution to produces H⁺ and electronegative IA^-. Therefore, IA^- can replace one H₂O molecule and form monodentate coordination with Zn²⁺, restructuring it solvation structure to optimize the deposition kinetics. Meanwhile, the H⁺ can neutralize OH^- produced from the hydrogen evolution reaction of the anode interface, inhibiting the formation of basic zinc sulfate by-products. Besides, IA^- can react with the Zn anode to form ion-conductive organic-inorganic hybrid solid electrolyte interfacial membrane film, while serving as a pH buffer during cycling. Benefit from above superiorities, the Zn//Cu half-cell achieves a high coulomb efficiency of 99.8% at 1 mA cm^-2 and 1 mAh cm^-2 in the 2 M ZnSO₄ electrolyte with 1.0% IA. The Zn//Zn symmetrical battery exhibits an ultra-long cycle life over 3900 h (1 mA cm^-2 and1 mAh cm^-2) and stable operation for 500 h at higher current density and area capacity (10 mA cm^-2/10 mAh cm^-2). Furthermore, Zn||NVO full battery can retain 120 mAh g^-1 after 4000 cycles. The synergistic modification strategy based on bio-derived molecules offers a new path for development of high-performance, sustainable AZIB electrolytes.