Lead acid battery with gelled electrolyte contained within compressed absorbent separator mat and method of making the same

Abstract

A method for producing a valve-regulated lead acid battery includes the steps of (i) providing a battery comprising a preformed positive electrode plate, a preformed negative electrode plate and a porous separator mat having pores and being compressibly disposed between the electrodes to define a cell assembly, and a container for securably and sealingly holding the cell assembly; (ii) forming a electrolyte mixture comprising an aqueous colloidal dispersion of silica and sulfuric acid that is a precursor to a flowable thixotropic gel; (iii) applying a vacuum to the container; and (iv) introducing a quantity of the gel-precursor electrolyte into the container under a vacuum so that the flowable electrolyte mixture penetrates into the pores of the compressed mat, whereby as the acid absorbs onto the plates, the flowable electrolyte solidifies and forms a thixotropic gel within the pores and around peripheral edges of the mat to surround and seal the cell assembly. A battery produced by these steps include (i) a positive electrode plate; (ii) a negative electrode plate; (iii) an absorbent glass mat compressibly disposed between the electrodes, wherein the glass mat is in substantial contact with both electrodes; and (iv) gelled electrolyte disposed within the pores of the compressed glass mat and around peripheral edges of the glass mat, wherein the gelled electrolyte comprises of an intimate mixture of colloidal alkali metal polysilica having a particle size from about 4 nanometers to about 20 nanometers and sulfuric acid.

Dependencies are inferred from the claim text.