Bifunctional electrolyte additive ammonium persulfate for high-performance aqueous zinc-ion batteries

The main issues encountered in aqueous zinc-ion batteries (ZIBs) include corrosion and passivation of the zinc anode, electrolyte decomposition leading to hydrogen evolution, and dissolution consumption of cathode materials. This study proposes the use of ammonium persulfate (APS) as an electrolyte additive to enhance battery performance. The addition of APS not only adjusts the solvation structure of Zn²⁺, reduces water activity, but also allows NH⁴⁺ ions to preferentially adsorb onto the surface of the zinc electrode, forming a protective layer and achieving dendrite-free zinc anodes. Results indicate that the inclusion of APS additive in the electrolyte can increase the specific capacity of zinc-ion batteries from 321 mAh g⁻¹ to 418 mAh g⁻¹. Additionally, batteries with APS exhibit superior stability. Under low current density, the battery lifespan can reach 2100 h and a coulombic efficiency can up to 99.6%. This study delves into the design of multifunctional electrolyte additives and provides valuable insights for the development of practical ZIBs.