Effect of phosphoric acid on the performance of low antimony grid of Pb-acid cell under constant current charging and discharging

Citation:
El-Rahman, A. H. A., S. A. Salih, and A. A. M. El-Wahab, "Effect of phosphoric acid on the performance of low antimony grid of Pb-acid cell under constant current charging and discharging", Mat.-wiss. u.Werkstofftech, 2011.

Abstract:

Effect of phosphoric acid on the performance of Pb-1.7%Sb grid of lead-acid cell is studied in 5 M H2SO4 by cyclic galvanostatic polarization and impedance spectroscopy. An increase in capacitance to a maximum is recorded during the initial stages of the electro-reduction of PbO2 into Pb(II) compounds and attributed to concurrent compositional and dimensional changes. These changes include removal of O2 bubbles, insertion of large amounts of H2SO4 and H2O. Efficiency of PbO2 formation decreases, while its rate of self-discharge increases with increasing the charging current and in the presence of H3PO4. The charge capacity increases with increasing the discharging current due to the decrease in the self-discharge. The charge capacity is lower in the presence of H3PO4. On increasing the cycle number, the corrodibility of the grid increases, because more layers of the surface Pb are involved in the self-discharge. H3PO4 significantly retards the effect of cycle number.

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