Development of a two-dimensional, moving mesh treatment for modelling the reaction chamber of the soluble lead flow battery as a function of state of charge for Pb and PbO₂ deposition and dissolution

During cycling of the soluble lead flow battery, solid layers of lead (Pb) and lead dioxide (PbO 2) are deposited and stripped from the electrode surfaces. As such, there is a change in geometry of the flow field within the battery. A detailed two-dimensional numerical model which simulates this change in geometry using a moving mesh technique is developed. The model accounts for deposition of Pb, PbO 2 along with the formation of lead oxide (PbO) during discharge of the PbO 2 deposit due to a side reaction which is commonly assumed in the literature. Over short time scales of around 1 hr charge/discharge periods, which are typically reported in the literature, the effect of this is small. However, over more realistic time scales (>1 hr), by applying this technique, significant differences are seen in the cell resistance and in the mass flow rate of electrolyte. As a result, a difference in cell voltage of up to 65 mV is seen over a 24 h period. The numerical results are validated against experimental data, showing an agreement in the voltage-time profile and a close fit for the moving mesh approach.