Physical change in positive-plate material — an underrated contributor to premature capacity loss

In spite of a broad and sustained research effort, premature capacity loss (PCL) remains the major barrier to the long term usage of lead/acid batteries in a range of demanding applications. Of greatest concern today is the manifestation of PCL that results in failure of the porous component of the positive plate. While much of the previous work in this area has focussed on the localized interactions between constituent particles of the porous material, we suggest that important bulk factors, such as plate compression and apparent density, have not received sufficient consideration. Indeed, evidence from experimental studies indicates that apparent density is the critical determinant of positive-plate performance and that compression is the primary means by which density is controlled in contemporary plate designs. Moreover, the extension of positive-plate cycle life depends on maintaining apparent density above a minimum value. In light of this relationship, we present strategies by which gains in plate performance can be achieved.