Investigating the Effects of Carbonate Additives on Zn-Air Battery

Alkaline zinc-air batteries (ZABs) exhibit high theoretical energy density and capacity, along with intrinsic safety and cost-effectiveness. However, the widespread adoption of ZABs is hindered by various challenges, including the vigorous hydrogen evolution reaction (HER) and zinc dendrite formation, which degrade discharge performance and increase safety risks. This study demonstrates a significant improvement in ZAB performance through the addition of an optimized concentration of sodium carbonate (Na2CO3) to the 7 M KOH electrolyte. Optimal performance was rigorously confirmed at 0.4 g Na2CO3. At this concentration, open-circuit potential-time profiles demonstrated exceptional stability, maintaining potentials around -0.39 V to -0.42 V over 600 seconds. Cyclic voltammetry revealed peak anodic currents of approximately 11 mA at ~-0.15 V for 0.4 g Na2CO3, indicative of superior zinc oxidation kinetics. Further, EIS analysis, encompassing both Bode and Nyquist plots, substantiated these findings, exhibiting higher charge transfer resistance and reducing the corrosion rate. This electrochemical characterization highlights the critical role of Na2CO3 as an electrolyte additive, with an optimal range that is crucial for balancing conductivity, suppressing passivation, and ensuring efficient redox reactions in zinc-air battery systems.