Lead-Carbon Electrode with Inhibitor of PbSO4 Recrystallization in Lead-Acid Batteries Operating on HRPSoC Duty

The major problem of lead-acid batteries for application in hybrid electric vehicles (HEV) is the progressive sulfation of the negative plates as a result of incomplete charge of the cells in the HEV mode of operation. Under these conditions, recrystallization processes take place whereby big PbSO4 crystals grow at the expense of dissolution of smaller ones. The present study has established experimentally that addition of poly-aspartic acid to the solution or to the negative paste retards significantly the crystal growth of lead sulfate crystals. Small PbSO4 crystals are highly soluble and sustain high concentration of Pb2+ ions in the solution, thus improving the charge acceptance of the cells. It has also been established that poly-aspartic acid increases the overpotential of hydrogen evolution on the lead electrode. Linear sweep voltammetry experiments and cycling tests of cells under simulated high-rate partial-state-of-charge conditions have confirmed the above effects of poly-aspartic acid.