Effect of Additives Reducing Solubility of ZnO on the Decomposition Kinetics of a Supersaturated Zincate Solution
Actual research in the field of Ni-Zn batteries deals with electrolytes with reduced ZnO solubility, which limit the amount of zinc transferred from electrode to electrolyte and back during cycling and thus reduce the electrode shape changes. These electrolytes are based on the alternative anion groups such as F-, CO32-, or PO43-. In many cases the battery development also considers the organic additives into the base electrolyte, which serve as Zn dendrite inhibitors. These additives are mostly surfactants, which means that they have also the ability to adsorb on the surface of any particles.
With respect to above-mentioned fact we focused our attention on the measurement of decomposition kinetic rate of SZS with regard to different additives, which are mostly used in the Ni-Zn batteries. Precipitation of ZnO is accompanied by the release of hydroxyl ions that linearly increase electrolyte conductivity as the decomposition process is ongoing. For this reason we determine the decomposition rate by conductometric measurements using a four electrode platinum-glass conductivity cell Knick Messcell 227. Conversion characteristic between the conductivity and concentration of dissolved zinc over the saturation state were determined by complexometric titration for the each type of measured electrolyte.
We trust, that our result, which describes the decomposition kinetic in low solubility electrolyte, can contribute to the better understanding of the complex phenomena of Ni-Zn battery.