Stainless steel foil: A more appropriate current collector than titanium foil for the cathodes of aqueous zinc ion batteries

Benefiting from the advantages in safety, reliability, affordability, and energy/power densities, aqueous zinc-ion batteries (AZIBs) with mildly acidic electrolytes have triggered tremendous research interest. However, Ti foil, as the most widely used current collector for cathodes of AZIBs, is rather expensive. In this work, stainless steel (SS) foil, with a much lower price, is proposed to be a more appropriate current collector than Ti, Ni, Al, and Cu foils. Among them, Ti and SS foils are found to own superior wettability with related solvents, excellent anti-corrosion ability, and strong binding with cathode material. In contrast, Al and Cu foils suffer from severe corrosion in aqueous electrolytes even without external potential, and Ni foil is electrochemically unstable in aqueous electrolytes. Further studies show that only Ti and SS current collectors can enable Zn//MnO2 battery to work normally. And SS foil behaves slightly better than Ti foil in both Zn//MnO2 battery and hybrid supercapacitor in terms of specific capacity, rate capability, and cyclability. This work provides guidance for the selection of current collectors for AZIBs and related energy storage devices.