Performance of zinc air batteries with added $$\hbox {K}_{2}\hbox {CO}_{3}$$ K 2 CO 3 in the alkaline electrolyte

Abstract

Intentionally adding potassium carbonate to the high molar alkaline electrolyte is one possibility to mitigate the negative impact of carbonation in zinc air batteries (ZABs) that were investigated in this novel study. In this work, an experimental analysis of the electrochemical performance of ZABs with added potassium carbonate in potassium hydroxide electrolyte was conducted. The experiments included polarization curve measurements, electrochemical impedance spectroscopy measurements, and constant current discharge with an in-house battery set-up. In addition, ionic conductivity was measured for mixtures of potassium hydroxide and potassium carbonate solutions. The results implied that up to 50 mol% of added potassium carbonate in the electrolyte had a weaker influence on the cell performance than a decreased amount of hydroxide ions in the electrolyte from 21.9 to 1.8 mol%. However, discharge measurements showed that the cell potential and the maximum state-of-discharge are decreased for the operation with 50.00 mol% of added potassium carbonate. The conductivity measurements revealed that solutions with 9 \(\hbox {mol} {\mathrm{\,l}}^{-1}\, \hbox {K}^+\) and added potassium carbonate possessed similar ionic conductivity, when compared to the standard 6 M KOH electrolyte. All in all, the analysis showed that it was acceptable to add potassium carbonate to the high molar potassium hydroxide electrolyte, while still obtaining stable cell potential under the premise to increase the practical energy density and the long-term stability of zinc air batteries. The here presented findings might help to establish the zinc air battery as next generation type battery.