Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Include electrolyte chemically specified and method
Reexamination Certificate
2001-05-29
2003-01-28
Weiner, Laura (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Include electrolyte chemically specified and method
C429S215000, C429S228000, C429S225000
Reexamination Certificate
active
06511771
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an improved lead acid battery element containing metal impurity inhibiting polymeric additives, which are added to the positive active material, negative active material and/or battery separator to inhibit the detrimental effects of certain metals on the efficiency of a lead acid battery, particularly the negative plate battery element and to macroporous additives that enhance active material utilization efficiency and improvement in the utilization of sulfuric acid electrolyte necessary for the discharge reaction of a lead acid battery.
Further, the present invention relates to the use of an acid resistant expander functioning amount of an organic polymer having phosphonic groups in the negative plate of a lead acid battery. Further, the present invention relates to the use of an acid resistant organic polymer having phosphonic groups in combination with the negative active material and an expander in the negative plate of a lead acid battery. The acid resistant organic polymer additives improve overall capacity maintenance.
Metal impurities can be introduced into a lead acid battery through the use of any of the materials used in the manufacture of the battery. For example, metal impurities can be introduced in the lead and leady oxides used in the manufacture of the active material, the materials of construction including the lead grids, alloying agents, electrolyte and water. Nearly all metallic impurities, if they are nobler than lead, have a smaller hydrogen overvoltage than pure lead. Therefore, they increase hydrogen evolution even if they are deposited in minute concentrations on the surface of the negative plates. These metals cause a continued gas evolution even after charging is completed. Hydrogen is evolved on the deposited metal with low hydrogen overvoltage, which can be short-circuited with lead. The effect of metal on the gassing particularly postcharge gassing decreases in the following sequence: Pt, Au, Te, Ni, Co, Fe, Cu, Sb, Ag, Bi and Sn. The presence of 0.3 ppm of platinum in the acid can cause a doubling of the self-discharge rate. Tin can produce this effect at 0.1%. Freshly deposited antimony is especially active. Besides the discharge of the negative plates with concomitant hydrogen evolution, these materials also move the end of charge voltage of the negative plates toward more positive values. The hydrogen evolution increases with rising acid density. Because the hydrogen overvoltage decreases with temperature, the self-discharge increases.
In addition, antimony is often added to grid lead in order to make the lead more fluid and more easily cast into the shapes necessary for storage battery grids.
Further, it also hardens the resulting casting so that it an be further processed in the plant without damage. In certain battery applications, it may be necessary for the battery to withstand extreme resistance to corrosion of positive plate grids. In that event, higher antimony contents typically within the range of 4.5 to 6 percent are incorporated into the grid to form a lead antimony alloy. Antimony in these concentrations are generally only used in positive grids particularly grids intended for corrosion resistant batteries. Corrosion resistance typically means the ability to withstand the destructive effects of excessive charge or overcharge.
Antimony in the grid metal produces a definite effect on the charge voltage characteristics of the fully charged wet battery. The higher the antimony percentage in the grid metal, the lower the charge voltage and conversely, as the antimony is decreased so the charge voltage increases until pure lead is attained, which produces the highest voltage on charge. Since the use of antimony has gradually been lowered from a maximum of about 12.0% to a maximum of about 6.0% antimony, the charge voltage of average batteries has increased.
Contaminant metals, hereinafter referred to as metal impurities including antimony from the positive grids, during service life, slowly goes into solution in the sulfuric acid electrolyte and from there it is believed to electroplate onto the surface of the negative plates. Once there, it acts as an additional electrode with the grid and the lead active material of the negative plates. This combination creates local action, promoting self-discharge and contributes to poor wet battery shelf life. In addition, the battery's charge voltage slowly decreases during life and, in the voltage regulated electrical circuit of a car, the difference between the two becomes greater. The car voltage regulator is set at a voltage just slightly higher than the normal charge voltage of the battery. Thus, the generator is able to restore electrical energy to the battery, as needed, to keep it charged. With metal deposition and the lowering of the battery charge voltage, the generator output into the battery increases as an overcharge, which hastens the deterioration of the battery in service, until failure occurs. Therefore, it is very desirable to inhibit the detrimental effects of antimony on the negative plate.
SUMMARY OF THE INVENTION
A new battery element which inhibits the detrimental effect of soluble metal impurity on the negative plate has been discovered. In brief, the battery elements include the addition of an organic polymer having functional groups with a preferential affinity for the metal impurity in the cation or anion state, to the positive active material, the negative active material or the separator which separates the positive and negative plates within a lead acid battery and which typically is a reservoir for sulfuric acid electrolyte.
A new battery element which improves utilization efficiency of the active material in a lead acid battery has been discovered. In brief, the battery elements include the addition of macroporous containing particle additives to the active material in the positive or negative plates of a lead acid battery to improve overall utilization efficiency and the utilization of sulfuric acid electrolyte during discharge of the battery.
A new battery element which improves capacity maintenance of the negative active material in a lead acid battery has been discovered. In brief, the battery elements include the addition of an acid resistant organic polymer having phosphonic groups associated with said polymer which functions as an expander in the negative active material to improve overall capacity maintenance. Further, the organic polymer having phosphonic groups can function cooperatively with the expander in the negative active material to improve overall capacity maintenance.
DETAILED DESCRIPTION OF THE INVENTION
In one broad aspect, the present battery elements comprise the addition of an organic polymer containing phosphonic functional groups to the negative active material having at least one expander component. In a preferred embodiment, the organic polymers are porous and have phosphonic functionality on both the outer surface and within the internal pore structure. The organic polymers function together with at least one expander component present in the negative active material to improve overall battery capacity maintenance.
In lead acid batteries an expander is added in small amounts to the negative active material and its primary function is to prevent the contraction and solidification of the spongy lead of the negative plate. The contraction, or the closing of the pores, in the negative plate can greatly reduce the capacity and the life of the negative plate and battery. Expanders are typically acid resistant materials, which are able to function in the presence of sulfuric acid electrolyte.
Expanders typically consist of an intimate mixture of barium sulfate, carbon or lamp black and a ligneous material often derived from wood. The expander promotes good battery performance, i.e., capacity maintenance, particularly in the areas of low temperature and high rate discharge capacity and for extended negative plate life. Although the exact mechanism of the expander has not been qu
Ensci Inc.
Uxa Frank J.
Weiner Laura
LandOfFree
Negative plate element for a lead acid battery does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Negative plate element for a lead acid battery, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Negative plate element for a lead acid battery will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3072766