Negative and Positive Plate Construction Methods

OPERATION AND CONSTRUCTION DOE-HDBK-1084-95 Lead-Acid Storage Batteries Batteries Page 14 Rev. 0 Figure 4. Typical planté plate. Negative and Positive Plate Construction Methods The simplest method for the construction of lead-acid battery electrodes is the planté plate, named after the inventor of the lead-acid battery. A planté plate is merely a flat plate composed of pure lead. Since the capacity of a lead-acid battery is proportional to the surface area of the electrodes that is exposed to the electrolyte, various schemes are employed to increase the surface area of the electrodes per unit volume or weight. Planté plates are grooved or perforated to increase their surface area. A typical planté plate is shown in Figure 4. The most commonly used method to increase surface area is to make the active material into a paste that acts like a sponge where the electrolyte fills all the pores. The paste, or active material, is mounted into a frame or grid structure that mechanically supports it and serves as the electrical conductor carrying the current during both the charge and discharge cycle. The most commonly used plate today is the pasted plate, also known as the flat plate. This grid structure is a lattice-work that resembles the cross section of a honeycomb, with the paste filling all of the rectangular windows on the structure. Figure 5 shows a typical construction of a pasted plate grid. The flat plate construction is used as the negative electrode plate in almost all cases, and serves as the positive plate in most standby applications.