Chemistry: electrical current producing apparatus – product – and – Deferred action type – Responsive to heat
Reexamination Certificate
1999-08-13
2001-03-20
Gorgos, Kathryn (Department: 1741)
Chemistry: electrical current producing apparatus, product, and
Deferred action type
Responsive to heat
C429S068000, C429S103000, C429S113000
Reexamination Certificate
active
06203939
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The high temperature battery in accordance with the present invention is a primary, thermal battery and does directly convert energy into electricity.
2. Description of the Related Art
The following descriptions of primary batteries, thermal batteries and direct conversion of energy into electricity are presented to indicate the prior art in these subjects.
The following definition of a battery is taken from the
Encyclopedia Britannica,
1965, Volume 3, pages 281 and 282. (Note that an anode and a cathode of a battery have a different polarity than the anode and cathode of a device which consumes electric current.):
BATTERY.
The term battery, as commonly used in electricity and electrochemistry, refers to a device for converting chemical energy directly to electrical energy. The mechanism of the process involves the arrangement of chemicals in such a manner that electrons are released in one part, or electrode, of the battery and caused to flow through an external circuit to the other part, or electrode. Such batteries are called voltaic cells.
The part of the battery at which the electrons are released to the external circuit is called the anode, or the negative electrode or pole; the part that receives the electrons from the external circuit is called the cathode or the positive electrode or pole. (The terms anode and cathode are used here in the accepted scientific sense in referring to components of a battery that produces electric current; in a device that consumes current—e.g., an electroplating cell, an electron tube, etc.—the term anode is commonly applied to the positive electrode while the negative electrode is called the cathode.) Familiar examples of batteries are the so-called dry cells used in flashlights, lead-acid batteries used in automobiles and mercury batteries used in hearing aids.
A primary battery is a non-rechargeable battery such as the common carbon-zinc or alkaline battery, and a secondary battery is one that can be recharged; these were extracted from “Batteries: Today and Tomorrow” by Don Mennie in the IEEE Spectrum of March 1976, pages 36-41.
The following thermal battery description is taken from High
Energy Batteries
by Raymond Jasinski, Plenum Press, New York, 1967, page 96 and following. In FIG. 3-3 “Fused salt” electrolytes are shown as operating from about 300° C. to about 1, 000° C.
Batteries employing this type of electrolyte are generally referred to as “thermal” batteries because of their heat-activation characteristics.
The cells are stored at ambient temperature, with the electrolyte a solid. This provides for a low self-discharge rate and a long storage life. When fused, the cells are capable of high discharge rates for short times. It has been in this area of high discharge rates (greater than 1 amp/sq.inch) (greater than 0.155 amp/sq.cm.) that the thermal battery has found most application.
In pulse performance at 70OF (21° C.) (Jasinski, page 211, reference FIG. 6-2), the molten salt/thermal battery exceeds all other types of batteries with a voltage per cell (VPC) of 2.0 volts and a discharge rate of 1.085 amps/sq.cm.(reference FIG. 6-2). Further, from Jasinski, pages 97-98:
The conductivities of molten salts are from 10 to 100 times higher than those of aqueous systems, so that molten salt cells should have low voltage losses due to the IR drop . . . The use of high currents requires that considerable attention be paid to elimination of ohmic resistance in other parts of the battery, e.g., contact resistance within the leads . . . At corresponding temperatures relative to the melting point, simple ionic salts do not possess physical properties radically different from other liquids.
Further, from Jasinski, page 111, under . . . Cell Materials—General, Negatives:
Aluminum. The equivalent weight of this material is 9. A high temperature cell has been described (Reference Publication A 280: L. Antipin,
Zh. Fiz. Khim.
30; 1425 (1956) (C.A. 51: 6394 i)) which has an aluminum negative and an O
2
/Cu positive. The electrolyte consisted of 40.5% AlF
3
, 57.85% NaF, and 2.65% Al
2
O
3
.
The following definition of an electrolyte is taken from the
Encyclopedia Britannica,
1965, Volume 8, page 230.
“ELECTROLYTE, in chemistry and physics, a substance which conducts electric current as a result of a dissociation into positive and negative ions, which migrate toward and frequently are discharged at the negative and positive electrodes, respectively. In those instances in which an ion is not discharged at a given electrode, some other substance present in the solution or forming part of the electrode is instead always oxidized at the positive electrode or reduced at the negative electrode. The most familiar electrolytes are acids, bases and salts, which ionize in solution in such solvents as water, alcohol, etc. Many salts, such as sodium chloride, behave as electrolytes when melted in the absence of any solvent; and some, such as silver iodide, are electrolytes even in the solid state.”
The following excerpts concerning battery electrolytes were taken from page 72 of “Electrochemical Vehicle Power Plants” by D. A. J. Swinkels, IEEE Spectrum, May 1968, pages 71-77 . . .
If the reaction product of the electrochemical reaction can serve as the electrolyte rather than being dissolved in another fluid, a simpler and potentially lighter system will result. This often occurs with fused-salt electrolytes . . . The power capacity of a battery is to a large extent determined by the ratio of the open circuit voltage (OCV) to the resistance of the electrolyte. The higher the OCV and the lower the electrolyte resistance, the higher the power density that can be attained, which leads to the selection of very active electrode materials to obtain the high OCV and to fused-salt electrolytes because of their low resistivities. Typical resistivities are 0.1 to 1.0 ohm-cm for fused salts, 1 to 10 ohm-cm for aqueous electrolytes, and 100 ohm-cm and greater for organic electrolytes and solid electrolytes. Electrolyte resistance is given by pl/A where p is electrolyte resistivity, l is electrolyte thickness, and A is electrode area, so that low resistances can be obtained even with high-resistivity electrolytes if they can be made sufficiently thin. Glass can be an ion conductor using positive sodium ions with a resistivity of about 100 ohm-cm at 300° C. However, by making the glass membrane thin (say 10
−3
cm) and using a large area the internal resistance of a battery can still be kept low.
The following excerpts about borax are taken from the
Encyclopedia Britannica,
Volume 3, 1965, pages 951 and 952 under the heading: Borax.
“Borax, a colourless substance, found in major quantity in the salt deposits of California and also in Chile, Tibet, Peru and Canada. It has an alkaline taste and is moderately soluble in water. When heated borax foams vigorously, losing the water shown in its formula (Na
2
B
4
O
7
.10H
2
O), and melts to form a clear glass. Molten borax dissolves many metallic oxides or salts to form boron glasses, some of which have characteristic colours.
Borax is used for the removal of oxide slags in metallurgy and in welding or soldering, for the detection of metals and for the production of coloured glazes on pottery. It is an important ingredient in many glasses and in enamels for ironware. It also finds application as a soap supplement or water softener. The discovery of the role of borax in plant nutrition led to the extensive use of borax in fertilizers . . .
. . . Although molten borax acts as an acid toward metal oxides, because of the excess of boron oxide in the formula (empirically 2NaBO
2
.B
2
O
3
), the aqueous solution is alkaline because of hydrolysis . . .
All polyborates of known structure contain the BO
3
unit, in which a boron atom is at the centre of an equilateral triangle outlined by three oxygen atoms. Such units share oxygen atoms to form condensed systems . . . ”
The following excerpt about borax glass when molten is taken from
Boron, Metallo-Boron Compound
Christie Parker & Hale
Gorgos Kathryn
Green Robert A.
Parsons Thomas H
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