Development of advanced electrolyte retainers for improvement of the life cycle of valve-regulated lead–acid batteries

Advanced electrolyte retainers have been developed to improve the life cycle of valve-regulated lead–acid (VRLA) batteries. One of the retainers is a separator mat which contains synthetic wood pulp (SWP), or fine polymer fibre. It shrinks less than conventional absorptive glass mat (AGM) when wetted with acid and is so elastic that the plates are kept well-pressed together when the volume of the plates changes during charge and discharge. The other retainer is granular silica which fills the space between and around the plates instead of the AGM. In a battery using this type of retainer, the plates are tightly compressed from all directions and the compression does not decrease after water loss. The basic characteristics of these new retainers and their influence on battery performance are discussed.