Effects of ZnSO₄ and Zn(CF₃SO₃)₂ Electrolytes on HER, Corrosion, Dendrite Formation, and Electrochemical Performance in Aqueous Zn‐Ion Batteries

ABSTRACT Aqueous zinc‐ion batteries (AZIBs) have garnered attention as a promising energy storage technology due to its low cost and improved safety. However, their practical application is hindered by challenges such as hydrogen evolution reaction (HER), zinc corrosion, and dendrite formation during repeated Zn plating/stripping cycles, which significantly affect cycling stability and electrochemical performance. Herein, investigations on the impact of ZnSO₄ and Zn(CF 3 SO 3 )₂ electrolytes at varying molar concentrations (1 M, 2 M, and 3 M) on these limiting factors are reported. Our results indicate that higher electrolyte concentrations are more effective in suppressing HER and corrosion while enhancing ionic conductivity. Notably, Zn(CF 3 SO 3 ) 2 demonstrated superior electrochemical performance compared to ZnSO₄, attributed to the bulky CF₃SO₃⁻ anions, which reduce the coordination between Zn²⁺ and water molecules, thereby facilitating faster ion transport. Hydrothermally synthesized α‐MnO₂ was utilized as the cathode in complete cell systems. Electrochemical tests demonstrated that a 3 M Zn(CF 3 SO 3 )₂ electrolyte enabled an impressive initial discharge capacity of 252 mAh g⁻¹. Additionally, the cell exhibited outstanding cycling durability and capacity preservation over repeated cycles. This enhanced electrochemical performance can be attributed to the distinctive characteristics of the Zn(CF 3 SO 3 ) 2 electrolyte, which effectively suppresses harmful side reactions while facilitating superior charge storage and transport processes.