Measurement of the electrolyte flow velocity and bubbles characterization during electrochemical reactions in lead-acid batteries using the PIV system

The fluid flow of electrolyte within the cells of the electrochemical batteries has a vital role on the performance of batteries. Many numerically and experimentally investigations have been carried out on this subject. In flooded electrolyte batteries during high rates charging and discharging process, due to the electrochemical reactions, insoluble gas bubbles are produced on the surface of electrodes and dispersed in the electrolyte. Despite the importance of the presence of bubbles on the electrolyte velocity and concentration field, in all studies, the presence of bubbles have been ignored. In this study, an experimental setup has been developed for measuring the electrolyte velocity in the flooded lead-acid batteries based on utilizing the Particle Image Velocimetry system. The results for different states of charge (SOCs) showed that by increasing the number of bubbles which occurs at high SOCs, the velocity of electrolyte flow increases. Also in the SOCs 40%, 60% and 100% compared to the SOC 0%, the averaged velocity of the electrolyte has increased about 16.8%, 29%, and 79%, respectively. The obtained results show that at higher SOCs, the effect of stratification phenomenon on the electrolyte velocity with respect to the effect of the presence of bubbles in the electrolyte is negligible.