LEAD ACID BATTERY HAVING ELECTRODES WITH FIBER MAT SURFACES

Abstract

Disclosed is an electrode for a lead acid battery formed of an electrode plate having a first side and a second opposing the first side, an active material paste applied to at least one of the first and second sides and a fiber mat embedded in the active material paste.

Claims

1. An electrode for a lead acid battery comprising: an electrode plate having a first side and a second opposing the first side; an active material paste applied to at least one of the first and second sides; and a fiber mat embedded in the active material paste.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIGS. 1-3 illustrate placing a fiber mat onto the surface of a plate immediately after pasting.

[0011] FIGS. 4 and 5 illustrate using a roller to apply the fiber mat to the surface of a plate.

[0012] FIG. 6 illustrates the plate after curing.

DETAILED DESCRIPTION OF THE INVENTION

[0013] A lead-acid battery comprises a positive electrode and a negative electrode separated by a separator and all immersed in an electrolyte. In one aspect of the invention, the positive electrode plate comprises a grid having first and second opposing sides to which a positive active material is applied. Similarly, the negative electrode is formed of a negative plate comprising a grid having first and second opposing sides to which a negative active material is applied. Now, there has been discovered a lead acid battery having a fiber mat embedded in active material paste applied to at least one of the first and second sides of one of the electrode plate. In one aspect, the lead acid battery is flooded lead acid battery. In one aspect, the plate is a positive plate and, in one aspect, a fiber mat is applied to both of the opposing sides of the positive plate.

[0014] Suitable fiber mats include fiberglass mats available from Johns Manville (Denver, Ohio). It is a distinct advantage of the invention that the fiber mats prevent mossing and positive active material shedding which will cause premature battery failure during cycling/field service

[0015] As illustrated in FIGS. 1-3, in one aspect of the invention, fiber mats having dimensions corresponding the surface of an electrode plate are placed on at least one of the opposing sides of the electrode plate to which an active material paste has been applied. (One side shown.) Then, in one aspect, as illustrated in FIGS. 4 and 5, after placing a fiber mat on one of the opposing surfaces of the plate to which an active material paste has been applied, pressure is applied by a roller to the exposed surface of the fiber mat to assure fiber mat penetrates (or embeds) into and adheres to active material.

[0016] After fiber mat is applied to at least one and, in some embodiments, both sides of the electrode plate to which an active material paste has been applied, the plate pate is cured. FIG. 6 illustrates the electrode plate after curing. Once the plates with at least one embedded fiber mat have been cured, the plates are ready to be used in a battery assembly process.

[0017] It is a distinct advantage of the invention that a fiber mat embedded in the active material paste applied to at least one of the first and second sides of a positive plate prevents or minimizes shedding and mossing issues from positive plates. During the charge/discharge cycling, the positive active material (PbO.sub.2) will go through an expansion and shrinkage cycle. This is mainly due to the density changes of chemical materials between the states of charge (lead dioxide, PbO.sub.2) and discharge (lead sulfate, PbSO.sub.4). Without wishing to be bound by a theory of invention, it is believed that the fiber mats hold/maintain the active material on the positive plates adhered to the grids for longer time which results in longer battery life. Applying this special fiber mat to the surface of both sides of the plates keeps the active material tight and strong during the cycling and, thus, delays material shedding and minimize premature battery failure conditions after repeated cycling/field service. Furthermore, a fiber mat embedded in active material paste applied to at least one of the first and second sides of a negative plate prevents or minimizes acid stratification, dendrite creation, antimony deposition and the like in connection the negative plate.