BARIUM METAPLUMBATE FOR LEAD/ACID BATTERIES

Addition of BaPbO3 to positive plates in a lead/acid battery improves formation efficiency and current acceptance of a deeply discharged battery. The battery containing 1% BaPbO3 in the positive plates can be formed three times faster with 12% less input capacity than that without the additive. The improvement in formation efficiency is more pronounced in the early stage of formation and is more significant for plates containing difficult-to-form materials. As formation proceeds, the contribution by the additive becomes less significant because the plate becomes more conductive due to formation of active materials. When attacked by sulfuric acid BaPbO3 decomposes to yield PbO2 which is an active material in the positive plate, and BaSO4 which is detrimental to the cycle life. The half-life of BaPbO3 in the battery acid at room temperature, determined from the rate constant of decomposition, is about 4 years. The rate of BaPbO, decomposition, however, increases with increasing temperature, acid concentration, and applied potential. The threshold of BaSO4 content to be detrimental to cycle life of a lead/acid battery is estimated to be about 0.30%. With 1% BaPbO3, appreciable formation enhancement can be obtained. At this level, decomposition of BaPbO3 to BaSO4 is not detrimental to the service life of the battery.