Separator design for valve-regulated lead/acid batteries

The wide commercial acceptance of valve-regulated lead/acid batteries for stand-by power applications over the last decade has involved the use of a novel separator material that is based on glass microfibre. The fibre materialʹs exceptionally small diameter (0.5–1 μm), high porosity (95%), zero contact angle, high anisotropy and good compressibility makes it significantly different from conventional flooded separators and, therefore, worthy of detailed study. Nevertheless, very little has been published on the mechanisms by which the electrolyte is retained and the oxygen transported within these nearly saturated recombination systems. This paper reviews critically some of the present methods for characterizing the glass-microfibre materials and suggests improved testing methods that reflect more accurately the subsequent effects on battery performance.