Phase Transformation Processes in the Active Material of Lead-acid Batteries

Abstract

The good performance of a lead-acid battery (LAB) is defined by the good practice in the production. During this entire process, PbO and other additives will be mixed at set conditions in the massing procedure. Consequently, an active material mainly composed of unreacted PbO, lead sulfate crystals, and amorphous species will be obtained. Later, the same mass will be pasted on the grids and the curing step will be performed. In this way, the previous pasted mass will be modified and a new hard porous structure will be formed in the active material. Furthermore, this structure will be bounded to the grid through a corrosion layer. Thus, the formed plate will be conducted to the following soaking and formation procedures. In these manufacturing steps, thanks to the major role of H2SO4, the active non-conductive material will be transformed into an electrically conductive element. Therefore, the prior compounds (PbO and lead sulfate crystals) will be converted to new phases: Pb or oxidized to PbO2 on the negative and positive plate, respectively. Because of the importance of the previous phase transformations, new advanced designs are focused on the internal structure of the active material to improve the LAB performance.