Inhibition of Hydrogen Evolution Corrosion and Surface Passivation of Zn Electrodes in Alkaline Electrolytes by Phosphoric Acid Ester Surfactants

Zn electrodes in alkaline solutions are prone to hydrogen evolution, corrosion, and surface passivation. To address these challenges, this work introduces a facile strategy employing mild phosphoric acid ester surfactants. We systematically investigate the influences of potassium lauryl ether phosphate (PLEP), tetrasopropyl methyldiphosphate (TM), and their blend (PLEP + TM) on the corrosion resistance and passivation behavior of Zn electrodes in alkaline electrolytes. The results demonstrate that PLEP increases interfacial resistance between the Zn electrode and KOH electrolyte due to its long alkyl chain, thereby significantly suppressing the hydrogen evolution reaction (HER) of Zn in KOH solution. TM possesses two phosphonic acid groups, conferring strong Zn²⁺ chelating capability, which prevents ZnO formation and thus markedly inhibits passivation of the Zn electrode in an alkaline solution. The PLEP + TM mixture with synergistic effects of PLEP and TM not only effectively suppresses the HER of Zn in alkaline media but also counteracts the significant interfacial resistance increase associated with PLEP. The addition of TM, PLEP, and the PLEP + TM mixture all enhances the discharge performances of alkaline Zn-MnO₂ batteries. This work provides a promising insight for simultaneously suppressing the HER and surface passivation of Zn electrodes in the alkaline electrolytes.