Electrochemical performance of novel Pb alloys reinforced with Ni-coated fly ash microballoon composite foams in Lead Acid Battery

Abstract

Novel Pb composite foams comprising hybrid gas pores and Ni-coated fly ash microballoons were produced by direct melt foaming method. Pb composite foams were designed to have a lower weight and larger surface area to be used in the Lead Acid Battery (LAB) as alternative to the traditional Pb grids, offering benefits in the transportation industry. The Ni-coated fly ash microballoons were added to Pb alloy melt to serve as thickening agent and pores, which were wholly enclosed within the microballoons, as well as reinforcements. The electrochemical performance of Pb grids used in traditional LAB and Pb composite foams produced in the present work was investigated for comparing purposes. The cured plates form positive and negative electrodes of Pb grid and Pb composite foams were characterized by X-ray diffraction to identify the different Pb compounds and phases. The morphology of the cured plate was found to contain flakes and dendritic structure. Zones were formed from a network of Pb particles in the negative electrode covered with PbSO4 crystals. The PbSO4 crystals exhibited miscellaneous morphology. The matrix of lead basic sulphate crystals was converted into aggregates of PbO2 particles in the positive electrode morphology, which maintained the form of the original substance. Cyclic voltammetry measurements (CV) were conducted in 3 M H2SO4 to study the anodic oxidation and cathodic reduction peaks of Pb, PbSO4 and PbO2. The galvanostatic polarization for oxidation and reduction steps was measured at different current densities. It revealed the benefit that the Pb matrix composite foam showed a longer period for oxidation of Pb into PbSO4. The composite foams exhibited a greater specific discharge electrical capacity than the Pb alloys used in traditional LAB.