Seeking enhanced lead/acid battery performance through the use of conductive tin-dioxide-coated glass-flakes

Abstract

The aim of this research is to raise the level of active-material utilization in the positive plates of lead/acid batteries (without diminishing other performance characteristics) and, thereby, to increase the energy output per unit weight. The strategy is to increase the electrical conductivity of the material by adding a proprietary particulate that consists of glass-flakes coated with a thin (<5 μm) layer of tin dioxide. The particulates are incorporated in positive plates that are prepared as automotive designs under a wide range of processing conditions, i.e., paste densities, acid-to-oxide ratios, low-/high-temperature (3BS/4BS) curing. Plate performance is evaluated in terms of active-material utilization, cold-cranking capability, repetitive reserve capacity, and life endurance under the Japanese Industrial Standard (JIS) procedure. Compared with untreated cells, the following benefits of adding the particulates to positive plates have been confirmed: (i) acceleration of the formation process; (ii) increase in the BET surface area of formed materials; (iii) improvement in active-material utilization at the 5-h and 20-h discharge rates; (iv) maintenance of cycleability under repetitive, reserve-capacity duty; (v) increase in cycle life under the JIS schedule. The encouraging outcomes of this research suggest that further benefits are likely to be gained by designing elongated particulates of lighter weight. This will increase the number of counts per unit area and, thereby, will improve the contact between the individual particles of the positive active material and will further enhance the electrical conductivity of the plate.