Investigation on electronically conductive additives to improve positive active material utilization in lead-acid batteries

In order to adapt lead-acid batteries for use in hybrid electric vehicles, its specific energy must be improved. Specific energy is greatly dependant on active material utilization. In this study, we improve active material utilization in positive electrodes by the addition of electronically conductive additives. Titanium silicide particles (<44 μm diameter), titanium dioxide fibers (<10 μm, diameter), and titanium wire (76 μm, diameter) were incorporated into the positive electrode and each of their effects on discharge capacity and utilization of active material were examined. The percent mass of each additive was varied from 2–5%. Results indicate that titanium wire at 2.3 wt.% had the optimal effect of increasing the utilization by 12.3% (57 to 64% utilization) relative to control with no additive at a slow discharge rate (10 mA cm−2) without detrimental effect at fast discharge rate (50 mA cm−2). This additive also features reduction in weight and formation enhancement.