Synergistic enhancement of zinc anode stability via bismuth alloying and CO2 exposure in 1 M KOH for alkaline battery applications

Abstract This study systematically investigates the electrochemical performance of pure zinc and zinc-0.5 wt% bismuth electrodes employed as anodes in alkaline battery systems using a 1 M KOH electrolyte, under both CO₂-free and CO₂-saturated environments. Electrochemical behavior was evaluated through potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge cycling. Surface morphology, elemental composition, and phase structure were analyzed using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX) and X-ray diffraction (XRD). The introduction of CO₂ markedly reduced the corrosion current density ( i corr ) of both electrodes, indicating a significant mitigation of corrosion processes. Notably, the zinc–bismuth alloy exhibited superior electrochemical performance compared to pure zinc. Under CO₂-containing conditions at 25 °C, the Zn-Bi electrode achieved a maximum corrosion inhibition efficiency of 87.615%. Galvanostatic cycling results further demonstrated enhanced charge–discharge behavior, improved capacity retention, and greater electrochemical stability in the presence of CO₂. These results highlight the strong potential of Zn-Bi alloys as durable and high-performance anode materials for advanced alkaline battery applications.