Capacity and cycle-life of batteries using bismuth-bearing oxide

An examination is made of the capacity performance of lead-acid positive el ectrodes which are prepared from bismuth (Bi)-bearing oxide. This oxide is produced from Pasminco VRLA Refined(TM) lead which contains 0.05 wt.% Bi. F or comparison, benchmark tests are performed on electrodes made from oxide with virtually no bismuth (< 0.005 wt.%). The change in capacity is investi gated by means of a purpose-built 'compression cell'. With this design, the positive active-material is constrained under the action of a desirable, c onstant force during charge-discharge cycling. In general, the capacity inc reases with the compressive force. Importantly, the use of Bi-bearing oxide yields higher initial capacity and then a significantly faster rise in cap acity to the full value with subsequent cycling. Commercial VRLA batteries made with Bi-bearing oxide exhibit a lower rate of self-discharge than thos e fabricated with conventional factory oxide. In addition, Bi-bearing batte ries provide good cycle-life under the International Electrotechnical Commi ssion (IEC) test. (C) 1999 Elsevier Science S.A. All rights reserved.