tailieunhanh - Improvement of the performance of the positive electrode in t he lead/acid battery by addition of boric acid

A major disadvantage of the lead/acid battery is the decrease in voltage during operation which makes it unsuitable for systems sensitive to voltage fluctuations. Additives like BaSO4 or SrSO4, which are isomorphous to PbSO4, have been used to overcome this problem. Phosphoric acid and the various phosphates have long been used to improve the performance of the positive electrode of the battery. A beneficial effect of phosphoric acid is to inhibit the rate of the self-discharge reaction of the positive electrode in the lead/acid battery. . | Jllim if ELSEVIER Journal of Power Sources 55 1995 11-17 Improvement of the performance of the positive electrode in the lead acid battery by addition of boric acid . Badawy . El-Egamy Department of Chemistry Faculty of Science University of Cairo Giza Egypt Received 16 November 1993 in revised form 6 September 1994 accepted 10 September 1994 Abstract A major disadvantage of the lead acid battery is the decrease in voltage during operation which makes it unsuitable for systems sensitive to voltage fluctuations. Additives like BaSO4 or SrSO4 which are isomorphous to PbSO4 have been used to overcome this problem. Phosphoric acid and the various phosphates have long been used to improve the performance of the positive electrode of the battery. A beneficial effect of phosphoric acid is to inhibit the rate of the self-discharge reaction of the positive electrode in the lead acid battery. However adverse effects of phosphoric acid include capacity loss in the initial cycles excessive mossing especially at high H3PO4 concentrations and poor 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 and impedance measurements. The results show that boric acid markedly improves the kinetics of the PbO2 PbSO4 couple and removes the problems encountered during the usage of H3PO4. Keywords Lead acid batteries Boric acid Positive electrodes 1. Introduction One of the main disadvantages of the lead acid battery is the decrease in voltage during discharge making them unsuitable for systems that require a stable power supply . relays used in telephone or railway stations. Addition of various species like BaSO4 and SrSO4 to the positive plate were used to overcome this problem since these materials are isomorphous to PbSO4 1 . Phosphoric acid and various phosphate derivatives have been used for the same purpose 2 3 and the effect