Improvement of positive plate grid corrosion resistance through two methods of boric acid addition to lead-acid battery electrolyte

Abstract

The performance of Lead-Acid Batteries (LABs) can be enhanced by the approach of incorporation of additives. In this way, boric acid (H3BO3) has been studied as an electrolyte additive as prior investigations have done. Nevertheless, the innovation provided by this work is based on the addition method employed. In fact, the H3BO3 effect on the LAB performance was measured when the addition was performed before and after the LAB formation. Firstly, a previous study was carried out in a three electrode cell to understand the effect of this additive on the positive grid. As a result, a decrease in the oxide reduction charge (23 %) and an increase in the resistance of the corrosion process were found by the addition of 0.50 wt% H3BO3. Furthermore, the research was then extended to a LAB system. Thus, 2 V/1 Ah cells were built and H3BO3 was added in different concentrations before and after the cell formation. Consequently, different effects were showed by the two addition methodologies. When the additive was introduced before the cell formation, the Cold Cranking Ampere (CCA) performance was improved (26 %). In contrast, when the additive was incorporated after the formation procedure, the Oxygen Evolution Reaction (OER) rate on the positive plate was significantly reduced (75 %). Lastly, the corrosion growth in the positive plate grid was slowed by the two methods although in different ways: 20 % reduction after 42 days of corrosion process (addition before formation) and 12 % reduction after 21 days of corrosion process (addition after formation). In addition, the prior cell performances were affected by the addition methodologies. If the additive was added to the electrolyte before the cell formation, the positive plate performance was possibly altered by the formation and growth of boric compounds in the PAM. However the cell performance was influenced by the suppression of OER on the positive plate when H3BO3 was added after the cell formation. In this way, different nuances of improvement were obtained due to the addition method applied.