Revealing the Multifunctional Nature of Surfactant Electrolyte Additive in Aqueous Zinc Ion Batteries

Abstract

Aqueous zinc ion batteries (ZIBs) have attracted increasing attention because of their safe aqueous electrolyte, relatively low price, and suitable energy density. Lots of researchers have reported the use of surfactants as electrolyte additives to improve battery performance in AZIBs, but most of them focus on the zinc anode issues. Here, the surfactant electrolyte additive strategy was used to investigate the effect of the cathode/ electrolyte interface on cathode dissolution suppression, self-discharge inhibition, and desolvation kinetics. As a result, the electrolyte with sodium dodecyl sulfate (SDS) additive immersed with hydrated sodium vanadate electrodes shows no significant color change during the 24-hour immersion test, while the original ZnSO₄ electrolyte turns yellow after only 0.5 hours. The discharge capacity of the electrolyte with SDS addition after the open-circuit voltage (OCV) test is 97.8% of the charging capacity before the OCV test, while the discharge capacity of the ZnSO₄ electrolyte is only 78.7%. These results demonstrate the surfactant electrolyte additive strategy could be a feasible way to construct robust ZIBs with suppressed cathode dissolution, inhibited self-discharge, and improved interface kinetics. This work provides new insights to understand the electrolyte additive and offers a reference for other energy storage systems.