In order to meet the increasing demand for valve-regulated lead–acid ŽVRLA. batteries, a new soft lead has been produced by Pasminco Metals. In this material, bismuth is increased to a level that produces a significant improvement in battery cycle life. By contrast, other common impurities, such as arsenic, cobalt, chromium, nickel, antimony and tellurium, that are known to be harmful to VRLA batteries are controlled to very low levels. A bismuth oxide has been manufactured ŽBarton-pot method. . | ELSEVIER Journal of Power Sources 73 1998 36-46 Oxide for valve-regulated lead-acid batteries . Lam a . Lim a . Haigh a . Rand a . Manders b . Rice b a CSIRO Division of Minerals . Box 312 Clayton South Victoria 3169 Australia b Pasminco Metals . Box 1291K Melbourne Victoria 3001 Australia Received 18 June 1997 accepted 17 August 1997 Abstract In order to meet the increasing demand for valve-regulated lead-acid VRLA batteries a new soft lead has been produced by Pasminco Metals. In this material bismuth is increased to a level that produces a significant improvement in battery cycle life. By contrast other common impurities such as arsenic cobalt chromium nickel antimony and tellurium that are known to be harmful to VRLA batteries are controlled to very low levels. A bismuth Bi -bearing oxide has been manufactured Barton-pot method from this soft lead and is characterized in terms of phase composition particle size distribution BET surface area and reactivity. An investigation is also made of the rates of oxygen and hydrogen evolution on pasted electrodes prepared from the Bi-bearing oxide. For comparison the characteristics and performance of a Bi-free Barton-pot oxide which is manufactured in the USA are also examined. Increasing the level of bismuth and lowering those of the other impurities in soft lead produces no unusual changes in either the physical or the chemical properties of the resulting Bi-bearing oxide compared with Bi-free oxide. This is very important because there is no need for battery manufacturers to change their paste formulae and paste-mixing procedures on switching to the new Bi-bearing oxide. There is little difference in the rates of oxygen and hydrogen evolution on pasted electrodes prepared from Bi-bearing or Bi-free oxides. On the other hand these rates increase on the former electrodes when the levels of all the other impurities are made to exceed by deliberately adding the impurities as oxide powders the .
