The pitfalls of using stainless steel (SS) coin cells in aqueous zinc battery research

Rechargeable aqueous zinc batteries afford a low-cost and highly efficient approach of utilizing clean energy. In laboratory-scale research on aqueous zinc batteries, stainless steel (SS) coin cells have been widely utilized to assess their electrochemical performance due to their simplicity and flexibility. However, our investigation has unveiled the significant occurrence of the hydrogen evolution reaction (HER) and the subsequent accumulation of insulating layered double hydroxides (LDH) in SS coin cell materials. To mitigate its adverse effects, we have implemented a titanium (Ti) foil as a spacer, which possesses the ability to suppress the HER and acts as a barrier to prevent direct contact between the electrolyte and SS materials. The introduction of a titanium spacer in the control group was proved to remarkably extend the lifespan of the zinc anode by more than tenfold. In light of these findings, we emphasize the importance of considering the HER occurring in cell components and recommend the adoption of Ti-protected cell configurations in the field of aqueous zinc batteries.