Cation–anion cooperative additives in aqueous zinc-ion batteries: Mechanistic insights and performance regulation

Electrolyte additives are essential for suppressing zinc dendrites and parasitic reactions, stabilizing cathodes, enhancing capacity, and expanding the temperature tolerances of aqueous zinc-ion batteries (AZIBs). This review mainly summarizes how cation–anion cooperative additives—both inorganic and organic salts—regulate Zn anode interfaces, cathode stability, and electrolyte microenvironments through solvation tuning and interfacial engineering. The key failure mechanisms of AZIBs are outlined, encompassing dendrite formation, the hydrogen evolution reaction, corrosion, passivation, and cathode instability. The multifaceted functionalities of cation–anion cooperative additives are then classified, including (i) Zn anode interfacial regulation (interfacial ion distribution and electric field, interphase formation on Zn, kinetics, and morphology), (ii) regulation of the electrolyte microenvironment (altering the solvation structure, ion association, H-bond network, and dissolved O 2 ), and (iii) enhancing cathode functionality (suppression of dissolution and shuttling, stabilization reaction pathways and structural evolution, and alteration of the cathode-side interfacial state). Finally, key future research directions are highlighted, involving advanced in situ and operando characterization, the rational design of multifunctional additive systems, cathode–electrolyte interphase engineering, and systematic performance evaluation under practical conditions, thereby guiding next-generation high-performance AZIB electrolytes. • Cation–anion cooperative additives act as coupled chemical units, enabling multiscale regulation in aqueous Zn-ion batteries. • Salt-based additives synchronously regulate the solvation structure, the interfacial chemistry, and the electrolyte microenvironment. • Cooperative ionic regulation suppresses Zn dendrites, stabilizes cathode reactions, and improves cycling robustness. • Mechanistic insights establish design principles for next-generation high-performance AZIB electrolytes.