Crystallogenesis in the Forming of Plates for the Lead‐Acid Storage Battery

Abstract

Changes in microstructure have been observed during the forming of the positive and negative plates which provide clues as to the optimum conditions for formation. The microstructure produced was found to be dependent on the conditions under which forming took place. The conversion to lead dioxide in the positive plate was found to be initiated on the surface of a definite type of crystal, as yet not identified. The quantity, size, and shape of this crystal varied with the temperature and specific gravity of the electrolyte and with the current density employed. The indications were that a basic sulfate crystal was being converted directly to lead dioxide, without change in external form, through some solid‐state reaction. The conversion to lead in the negative plate was definitely by solution of the lead sulfate and deposition of reduced lead. The form and size of the lead crystals in the negative could also be varied with method of forming, but not to the extent of those in the positive plate. While there was indication that subsequent life of the positive plate might depend on the microstructure developed during forming, there was no such correlation found for the negative plate.