Prismatic Nickel-Zinc (NiZn) batteries with energy densities higher than 100 Wh kg −1 were prepared using Zn electrodes with different initial morphologies. The effect of initial morphology of zinc electrode on battery capacity was investigated. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) reveal that initial morphology of zinc electrode changes drastically after a few charge/discharge cycles regardless of initial ZnO powder used. ZnO electrodes prepared using ZnO powders synthesized from ZnCl 2 and Zn(NO 3 ) 2 lead to average battery energy densities ranging between 92 Wh kg −1 and 109 Wh kg −1 while using conventional ZnO powder leads to a higher energy density, 118 Wh kg −1 . Average discharge capacities of zinc electrodes vary between 270 and 345 mA g −1 , much lower than reported values for nano ZnO powders in literature. Higher electrode surface area or higher electrode discharge capacity does not necessarily translate to higher battery energy density.

In this study, the effect of initial kefir grain concentration and various minerals (MgO, MgSO4.7H2O, ZnSO4.7H2O, CaSO4.1/2H2O and Fe2O3) on the propagation of kefir grains and the pH evolution of kefir were investigated. The activated kefir grains were inoculated into very low fat (0.1%) cows’ milk under constant temperature (25°C) and impeller speed (100 rpm) for a propagation time of 24 h. Several mathematical models proposed to predict the pH value and kefir grain biomass increase vs propagation time were evaluated by the experimental results for all mineral additions; the Richards equation was found to be the most appropriate one. After evaluation of the experimental data, the most influential mineral addition providing 46.3% increase in kefir grain biomass was found to be MgO with a concentration of 0.30 g Mg2+/L. At this optimal condition, a model was derived for the kefir grain biomass concentration representing pH dependence.

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