IMPROVEMENT OF THE PERFORMANCE OF THE POSITIVE ELECTRODE IN THE LEAD ACID BATTERY BY ADDITION OF BORIC-ACID/

A major disadvantage of the lead/acid battery is the decrease in volta ge during operation which makes it unsuitable for systems sensitive to voltage fluctuations. Additives like BaSO4 or SrSO4, which are isomor phous to PbSO4, have been used to overcome this problem. Phosphoric ac id and the various phosphates have long been used to improve the perfo rmance of the positive electrode of the battery. A beneficial effect o f phosphoric acid is to inhibit the rate of the self-discharge reactio n of the positive electrode in the lead/acid battery. However, adverse effects of phosphoric acid include capacity loss in the initial cycle s, excessive mossing, especially at high H3PO4 concentrations, and poo r low-temperature performance (decrease in the rate of PbSO4 oxidation ). The effect of boric acid as an additive substituting for H3PO4 has been investigated using linear sweep voltammetry, constant potential a nd impedance measurements. The results show that boric acid markedly i mproves the kinetics of the PbO2/PbSO4 couple and removes the problems encountered during the usage of H3PO4.