Materials in the design of recombination lead-acid cells

Abstract

To ensure that the oxygen cycle operates efficiently in a lead-acid cell there must be a surplus of uncharged negative material, maintenance of a high hydrogen overvoltage on the negative plate, and ease of migration of oxygen from the positive to the negative plate. The selection of grid alloy and separator material is therefore critical. The properties of potential grid alloys are compared. The preferred alloy contains 0.05-0.08% calcium and 0.3-0.65 tin. The preferred separator is made from glass fibers of diameter 0.1 to 10 microns. It has an internal surface area in the range 0.17 to 15 m/sup 2//g and will immobilize the electrolyte. Its average pore size is greater than those of the positive and negative active materials, and the larger pores in the separator will therefore be unfilled with electrolyte, leaving paths for transport of oxygen.<>