The Effect of Expanded and Natural Flake Graphite Additives on Positive Active Mass Utilization of the Lead-Acid Battery

The effects of expanded and not expanded (natural flake) graphite additives were evaluated on the discharge utilization of the positive active material (PAM) in the lead-acid battery. Graphite powders were added to the paste at 2.20 vol. % and tested in model 2V battery cells under a wide range of discharge currents from 8C to C/20. The effects of graphite on the PAM pore volume and pore size distribution were measured with mercury porosimetry, and a good correlation was found between the pore volume of the PAM and utilization performance of the cells. It was shown that the powder characteristics of graphite can affect the PAM pore volume. A correlation was found between the graphite additives’ structural order and PAM utilization.