Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Include electrolyte chemically specified and method
Reexamination Certificate
1999-11-02
2001-05-01
Maples, John S. (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Include electrolyte chemically specified and method
C429S234000
Reexamination Certificate
active
06225001
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is related to electrical energy generation and can be used in power plants in which it is necessary to use transportable or non-transportable sources of electrical energy with high capacity, long service life and short charging time.
It is known to use electrical batteries to accumulate electrical energy. The widely used battery is a lead battery, which usually includes two lattice lead plates filled with a paste of lead oxide mixed with water. The plates are inserted in a vertical position into a water solution of sulfuric acid with density 1.15-1.20 g/cm
3
(22-28%. As a result of the reaction
PbO+H
2
SO
4
+H
2
O
lead oxide, after a certain time, is transformed into lead sulphate. When electric current passes through the battery from external current source during charging, negative ions SO
4
—move to the anode and transform the lead sulphate into lead peroxide according to the formula:
PbSO
4
+SO
4
+2H
2
0═PbO
2
+2H
2
SO
4
.
Positive hydrogen ions move to the cathode and reduce the sulphate into metallic lead according to the formula
PbSO
4
+H
2
═Pb+H
2
SO
4
.
As a result, after passage of the electric current, the two plates become sharply asymmetric, since one of them becomes a lead plate and the other becomes a lead peroxide plate. The battery is charged. It is a galvanic pair, which is capable of being an electric current source. Electromotive force of this battery at full charging is raised to 2 volts. When the battery supplies the electric current to an external circuit, it discharges and all processes proceed in an opposite direction. At the end of discharging both plates are covered with identical layers of lead sulphate and electromotive force falls down to zero. However, in practice, at the end of discharging the electromotive force does not reduce below 1.85 volts, because the battery is destroyed with more discharging.
Capacity of the battery is determined by a quantity of positive and negative active mass and the number of pores they contain, as well as by quantity and concentration of a solution of sulfuric acid in electrolyte and the design of the battery. The drawbacks of known batteries include a small battery service life, small capacity, long charging time, small weight of the positive active mass, as compared with the lattice lead plates where the active mass is located, and small coefficient of utilization of the positive active mass.
The battery service life depends on the service life of the positive plates due to corrosion of metallic lattices and decrease of the positive active mass. The lattice plates of the positive electrode have direct contact with the electrolyte-water solution of sulfuric acid when the electric current passes through the electrolyte of the battery during charging, and the negative ions SO
4−
−
and O
−
move to the metallic lattice. The negative ions SO
4−
−
and O
−
have open bonds, and therefore active interaction with the material of the lattice takes place and the material is destroyed. The second factor which substantially limits the service life of the known battery is a fall of the positive active mass PbO
2
. As a result, the positive plates and accordingly the positive active mass in the known batteries are relatively thin, which substantially limits the battery capacity. Because of the fall of the positive active mass, the weight of the lattice lead plate is too big when compared with the positive active mass. Thin lattice lead plates can support only small positive active mass. The coefficient of utilization of the positive active mass is low. It can be increased by providing the positive active mass with a great number of pores. However, the fall of the positive active mass is so extensive that the battery becomes disabled in a very short time. Even with a very small quantity of pores (dilator), this negative effect takes place.
The fall of the positive active mass becomes stronger with increase of concentration of sulfuric acid in the electrolyte. In order to counteract this fall of the positive active mass, the battery is provided with special separators pressed to the positive plates. However, it prevents expansion of the positive active mass. Also, the inner resistance of the battery is increased. The separators also make difficult access of sulfuric acid to the plates with the active mass, and the quantity of sulfuric acid in the battery is diminished. The voltage drops substantially inside the battery when the electric current is high. In the presence of the separators, the substantial part of potential drop is lost uselessly. The consumption of sulfuric acid per unit time is high when the electric current discharging the battery is high and the pores of the separators do not allow passage of required quantities of sulfuric acid. Thus, the fall of positive active mass is a second factor which strongly limits the service life and the capacity of the lead battery.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a method of accumulation of electrical energy and an electrical battery with a substantially longer service life and higher capacity and substially shorter charging time.
In keeping with these objects, in the present invention an electric battery has a positive electrode, a collector, and an electrolyte solution of sulfuric acid, in which a positive active mass is accommodated in a cuvette disposed horizontally and composed of a material which does not interact with the solution of sulfuric acid.
The cuvette can be composed of organic material which does not interact with the sulfuric acid solution. The collector can be placed on the bottom of the cuvette for electrical contact with the positive active mass PbO
2
. The collector has a terminal for outside electrical contact during charging and discharging of the battery. The collector is formed as a plate adjoining the surface of the cuvette. The cuvette is filled with the positive active mass over the collector. Therefore, the collector is isolated from direct contact with the solution of sulfuric acid-electrolyte from all sides, with the exception of the portion in contact with the positive active mass. This substantially prevents dissolving of the collector and therefore provides a long working time of the battery.
The terminal from the collector is covered with an organic protective layer (pellicle) to protect it from direct contact with the sulfuric acid solution. Since the collector is protected from direct contact with the electrolyte, it is possible to use not only lead, but also other metals, to make the electrode, for example of aluminum. Usually, the sulfuric acid solution dissolves aluminum, especially due to the heating. The contact of lead and aluminum with the positive active mass PbO
2
promotes creation of an oxide pellicle on the surface of metal and, therefore, interaction of lead and aluminum with the sulfuric acid solution slows down. If the collector is made of aluminum and is twice thicker than the lead electrode, the weight of the aluminum electrode is only half and, therefore, the battery weight is substantially reduced. Thus, the isolation of the collector from direct contact with the electrolyte contributes to considerable increases in the service life of the collector and the battery as a whole.
The positive active mass placed in the cuvette, which is disposed horizontally, eliminates the fall of the positive active mass. Therefore, a sufficiently thick layer (80 mm and more) can be used as a positive active mass. This increases the capacity of the battery and reduces the weight of the collector relative to the active mass. As a result, the capacity of the battery per unit weight is much greater than in the known batteries.
Since the positive active mass cannot fall, it is not necessary to use the separators, therefore, the inner resistance is reduced and power losses, especially with large electric currents of charging and discharging of the battery are
Maples John S.
White Eagle International Technologies, Inc.
Zborovsky I.
LandOfFree
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