WO2002039515A2 - Structure for a metal-air battery cell having a brass casing element - Google Patents
Structure for a metal-air battery cell having a brass casing element Download PDFInfo
- Publication number
- WO2002039515A2 WO2002039515A2 PCT/IB2001/002124 IB0102124W WO0239515A2 WO 2002039515 A2 WO2002039515 A2 WO 2002039515A2 IB 0102124 W IB0102124 W IB 0102124W WO 0239515 A2 WO0239515 A2 WO 0239515A2
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- WIPO (PCT)
- Prior art keywords
- casing
- casing element
- battery cell
- wall
- anode
- Prior art date
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M12/00—Hybrid cells; Manufacture thereof
- H01M12/04—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type
- H01M12/06—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type with one metallic and one gaseous electrode
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
- H01M50/116—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material
- H01M50/124—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material having a layered structure
- H01M50/126—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material having a layered structure comprising three or more layers
- H01M50/128—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material having a layered structure comprising three or more layers with two or more layers of only inorganic material
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
- H01M50/102—Primary casings, jackets or wrappings of a single cell or a single battery characterised by their shape or physical structure
- H01M50/109—Primary casings, jackets or wrappings of a single cell or a single battery characterised by their shape or physical structure of button or coin shape
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
- H01M50/116—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material
- H01M50/117—Inorganic material
- H01M50/119—Metals
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
- H01M50/131—Primary casings, jackets or wrappings of a single cell or a single battery characterised by physical properties, e.g. gas-permeability or size
- H01M50/133—Thickness
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
- H01M50/102—Primary casings, jackets or wrappings of a single cell or a single battery characterised by their shape or physical structure
- H01M50/103—Primary casings, jackets or wrappings of a single cell or a single battery characterised by their shape or physical structure prismatic or rectangular
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
- H01M50/116—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material
- H01M50/124—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material having a layered structure
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
- H01M50/116—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material
- H01M50/124—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material having a layered structure
- H01M50/1245—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material having a layered structure characterised by the external coating on the casing
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Definitions
- the present invention relates to leak-proof structures for prism-shaped and button- shaped electrochemical cells, in particular, metal-air cells. More particularly, this invention relates to the structure and material of an anode casing element that is made at least partly of brass and preferably, entirely of brass.
- the container of the battery cells, or its casing elements may be made of a thin, lightweight material.
- the casing elements makes up a large fraction of the weight of the cell. The need to minimize the thickness of the material of the casing elements must be balanced against the need for strength since electrochemical cells can place severe demands on cell housing designs.
- the material of the casing elements can also play a major factor in the performance of the battery cell. Certain materials may react negatively with the chemicals contained within the battery cells and result in the corrosion of the anode.
- the casing elements behave as the electrodes of the cell and thus must be able to conduct electricity and make adequate connectivity with the connectors of an electronic device.
- a casing element out of a tri-clad of material having layers of nickel, stainless steel, and copper. Each of the three layers provides a benefit to the overall structure and operation of the battery cell.
- the layers of material are arranged so that the layers of copper and nickel sandwich the layer of stainless steel with the layer of nickel exposed to an exterior of the battery cell and the layer of copper contacting the anode of the battery cell.
- the layer of stainless steel provides strength benefits.
- the layer of nickel provides aesthetic and connectivity benefits, and the layer of copper (which contacts the anode of the battery cell) provides connectivity and protection benefits.
- the layer of copper is coated with mercury, which is sometimes present in a zinc anode of a zinc-air battery cell. In this way, the mercury protects the copper from dissolving in the alkaline zinc anode.
- a known metal casing design e.g., button cells
- the grommet prevents the casing elements from contacting each other and also effectively seals electrolyte in one portion of the cell from other parts of the cell.
- the dimensions of the gap occupied by the grommet may change, and electrolyte may work its way around the grommet and leak through that gap.
- the raised internal pressure of the casing can force electrolyte out through the gap.
- metal-air battery cells the surfaces of the battery cells have small air access holes to permit the diffusion of oxygen. In metal-air battery cells, ambient oxygen reacts with the metal anode to generate electrical current.
- the holes are the means through which ambient oxygen can enter the battery cell.
- One of the risks of having holes in the cell is the possibility that electrolyte will leak out of the battery cell through the same holes. Further, the risk is exacerbated by the possibly raised internal pressure of the casing.
- Casing deformation causes electrical shorts when the metal casing elements contact each other or when opposite-polarity electrode materials inside the cell come into contact. Casing deformation can also cause the battery cell to lose electrical contact with the electronic device. A change in the dimensions of the battery cell can cause the electrodes to separate from the electrical contacts of the electronic device.
- button-shaped battery cells are intrinsically strong and are commonly used to power watches, hearing aids, etc. Forces applied to the major surfaces of a button cell are resisted by the inherent strength of the cylindrical structure.
- a button cell 10 has an internal pressure that is greater than ambient pressure.
- the button cell 10 has two major casing elements 12, 14 that are engaged to form a button-shaped enclosure.
- a peripheral bend portion 16 which shapes the outer casing element 12 over the inner casing element, prevents the two casing elements 12, 14 from separating.
- An internal pressure, which is represented by a force F ls pushes the two casing elements 12, 14 in a direction of separation from each other.
- This separation force Fj is resisted by a force F 2 , which is the force that the bend portion 16 exerts on the separating casing elements 12, 14.
- a button cell 20 has two casing elements engaged to each other.
- the inner and outer casing elements each have a side wall 22, 24, respectively, with a grommet 26 positioned therebetween.
- the diameters of the side walls 22, 24 may change.
- the diameter of the internal side wall 22 changes due to the force of the internal pressure
- the diameter of the external side wall 24 changes due to the force exerted by the internal side wall 22 via the grommet 26. Even if the diameters change, the grommet 26 adequately seals the casing elements together.
- a rectangular, prism- shaped cell 30 also has two casing elements with the inner casing element having four side walls 32 and the outer casing element having four side walls 34 and a grommet 36 positioned between the side walls 32, 34.
- the side walls 32, 34 tend to distort because they lack the inherent strength that a cylindrical shape has to resist deformation.
- the side walls 32, 34 do not maintain their shape.
- the centers of long spanning side walls tend to deflect a greater distance from their original position causing significant deformation and leakage problems.
- the strain around the perimeter of the side walls 32, 34 of the prism-shaped cell 30 are considerably more variable than the strain around the circumference of the button cell of Fig. 2.
- non-button shaped battery cells have only been commercially produced in limited quantities and certain applications, despite the obvious benefits in terms of packing density. That is, rectangular prism-shaped battery cells can fill a common rectilinear battery pack design with a significantly higher packing density than button cells, making the use of button cells unattractive. Solutions to the inherent weaknesses of prism-shaped cells must be addressed before prism-shaped battery cells can become a commercially feasible alternative. In a prism-shaped cell, casing deformation can present serious problems. Unlike button-shaped battery cells, the forces due to increased internal pressure are not distributed uniformly around the perimeter of the cell of a prism-shaped cell, nor can the forces be adequately resisted by hoop strength. A prism-shaped cell normally has long spans running from corner to corner. The long spanning wall portions of such a prism-shaped cell are inherently weak and susceptible to deformation.
- a metal-air button cell 40 has two interfacing, inter- engaging casing elements 42, 52.
- the cathode and anode casing elements 42, 52 are shaped to each have a substantially cylindrical-shaped side wall 46, 56, a major wall structure or base 48, 58, a peripheral corner 50, 60 positioned between the wall 46, 56 and the base 48, 58, and a peripheral edge 44, 54 forming an opening of the casing element 42, 52, respectively.
- These casing elements 42, 52 are assembled so that the bases 48, 58 form two oppositely positioned and oppositely charged surfaces of the battery cell 40.
- a grommet 62 positioned between the side walls 46, 56 electrically insulate and seal the casing elements 42, 52, and an approximately 45 degree bend 43 of the cathode casing element 42 prevents the casing elements 42, 52 from disengaging.
- the prior art example also illustrates the peripheral edge 54 of the anode casing element 40 as being sharp, which often results from a shearing operation in the manufacturing process.
- This sharp edge 54 can dig into and damage the grommet 62, causing electrolyte leakage and possibly a short circuit. Further, this sharp edge 54 can also bring about an undesired chemical reaction.
- the triclad may chemically react with the electrolyte, resulting in the production of hydrogen or the introduction of contaminate ions into the electrolyte. Normally, a coating or film on the surface of the triclad is added to inhibit this reaction.
- the shearing operation of the manufacturing process can expose the underlying nickel and thereby increasing the rate of the reaction.
- Fig. 4 also illustrates the side walls 46, 56 of the casing elements 42, 52 as being relatively perpendicular to the major surfaces 48, 58. In other words, the side walls 46, 56 are parallel.
- One problem with this configuration relates to the assembly of the battery cell 40. Since the internal components are placed on the bottom (near the base 48) of the cathode casing element 42, the components must work its way down the entire height of the side wall 46. Dimensional tolerances in the components of the casing element 15 may cause the components to get stuck or become distorted as they move to their ultimate location.
- Fig. 4 also illustrates the placement of the grommet 56 between the relatively smooth surfaces of the casing elements 42, 52.
- electrolyte e.g. KOH
- many different types of electrolyte e.g. KOH
- Scratches on the surfaces of the casing elements 42, 52 can act as channels through which electrolyte can migrate and eventually leak out of the battery cell 40. Electrolyte leakage can cause the battery cell 40 to short circuit or even explode.
- the present invention provides a button-shaped or prism-shaped casing made at least partly or solely of brass.
- the present invention also provides features that make the casing strong, unlikely to deform, and leak electrolyte.
- the present invention provides features that make the battery cell more reliable, inexpensive and mass-manufactureable. Ridges or ribs formed on the major flat surfaces of the battery cell are formed to add strength to the casing. These ridges eliminate or reduce the tendency of the battery cells to bulge due to an increase in the internal pressure of the cell or any other forces, such as the forces due to the assembly of the battery cell.
- the side walls of the casing elements flare outwards from the flat surface to prevent the walls from collapsing inwardly and to make the battery cell easy to assemble.
- the side walls are also shaped to provide for a better seal between the casing elements, thus preventing electrolyte from leaking.
- Tar or another liquid type sealant coats a grommet positioned between the casing elements to prevent electrolyte leakage.
- the grommet also serves to separate and insulate the two casing elements. Further, a diaper ring placed between the casing elements absorbs electrolyte that may have worked its way past the grommet. In the alternative, tar, by itself, can take the place of the grommet and behave as the insulating element.
- Brass has been shown to exhibit certain properties that are desirable in a design for a casing element for metal-air battery cells.
- brass is highly workable and does not react as negatively with a zinc based anode as other metals.
- Brass can be easily forged into various shapes suitable for a casing element and may be the preferred method of forming the casing element given factors such as costs and tolerance requirements.
- Brass is also an electrical conductor and therefore can be used as the electrical contact or electrode of the battery cell.
- brass is less expensive and more readily available thansuitable materials used as casing elements, e.g., triclad. The use of brass may be even more desirable in zinc-air battery cell applications, where the zinc anode does not contain mercury.
- mercury is sometimes used to protect the anode casing element from the alkaline properties of the zinc anode.
- mercury is not environmentally friendly and is sometimes eliminated altogether in the designs of many disposable batteries.
- Brass is a suitable material for a casing element in battery designs with little or no mercury or in designs with or without other corrosion inhibitors or additives such as phosphate ester, an ethylene oxide polymer, indium, bismuth, or lead.
- a coating of tin, indium, or gold may be applied on the concave surface of the brass anode casing element. The coating provides a layer of corrosion prevention.
- An anode casing element made entirely of brass may provide significant cost benefits. Besides the benefits identified above, an anode casing element made entirely of brass may be less expensive to manufacture than a casing element having brass as a part of the entire casing element. Brass also exhibits less desirable properties. In particular, it is not as strong as other materials such as stainless steel. Brass is a relatively ductile material and, in a metal- air battery cell application, may deform due to the internal and external forces present during the assembly and discharge of a metal-air battery cell. Therefore, it may be desireable to incorporate features to improve the strength of brass casing element. The present invention also provides for certain shape features that increase the strength of the casing elements made at least partly of brass. These features may be especially important in prism-shaped battery cells.
- forming a ridge, rib or indentation on the flat major surface and/or near the edges of the battery cell casing may provide additional strength to resist the interior and exterior applied forces.
- the shape features may also provide enough strength to resist the forces that the casing element experiences during the assembly or crimping process.
- one casing element in a two casing element design, one casing element may be made at least partly or brass and the other casing element may be made of a stronger material, such as stainless steel or the tri-clad material described above.
- the use of brass for both casing elements may not be desirable in certain metal-air battery designs.
- the use of brass in both casing elements may not be necessary.
- the use of a stronger material for the casing element that does not contact the metal anode may provide strength to the structure of the battery cell.
- the present invention also provides for a tray-shaped casing element having a ratio of the height of side walls to the surface area of the flat major wall that falls within a desired range.
- a casing element design within the desired ratio may provide the needed strength to resist substantial deforming due to interior and exterior forces.
- Prism-shaped metal-air battery cells are illustrated in the description of the invention because the metal-air battery cells are particularly suitable for describing many of the features of the invention. While the embodiments are described in relation to a rectangular shaped battery cell, the invention is not limited to battery cells having rectangular casings. Instead, the invention covers all prism-shaped battery cells, including but not limited to button, hexagonal, octagonal, and other cells having casings with relatively straight side walls with curved corner portions.
- Fig. 1 shows a cross-section representation of a button-shaped battery cell with vectors representing some of the forces that are present when the internal pressure is greater than ambient.
- Fig. 2 shows a different cross-section representation of a button-shaped battery cell.
- Fig. 3 shows a cross-section representation of a prism shaped battery cell with an internal pressure that is greater than ambient.
- Fig. 4 shows a cross-section representation of a prior art example of a button- shaped metal-air battery cell.
- Fig. 5 shows an enlarged, partial cross-section representation of the embodiment of Fig.4.
- Fig. 6 shows a cross-section representation of the embodiment of Fig. 4 with collapsing side walls.
- Fig. 7 shows a partial cross-section representation of one example of the prior art.
- Fig. 8A shows a cross-section representation of a prism-shaped battery cell according to one embodiment of the invention.
- Fig. 8B shows a different cross-section representation of the embodiment of Fig. 8A.
- Fig 9 shows a cross-section representation of an uncrimped cathode casing element of one embodiment of the invention
- Fig. 10 shows a perspective view of the uncrimped cathode casing element of Fig. 9
- Fig. 11 shows a perspective view of a cut-out portion of a cathode casing element under a bending moment.
- Fig. 12A shows a perspective view of an uncrimped cathode casing element according to an alternative embodiment of the invention.
- the casing element has notches at the rounded corners.
- Fig. 12B shows a perspective view of another uncrimped cathode casing element according to an alternative embodiment of the invention.
- Fig. 12C shows a cross-section representation of an assembled battery cell according to an alternative embodiment of the invention.
- Figs. 12D(1) and 12D(2) shows two enlarged partial cross-section representations of a single embodiment according to the invention.
- Fig 13 shows a cross-section representation of an anode casing element of the embodiment of Fig. 8.
- Figs. 14 - 18 show enlarged partial cross-sectional representations of edges of an anode casing element according to alternative embodiments of the invention.
- Figs. 19 - 21 show cross-section representations of ridges or ripples on a base of a casing element according to alternative embodiments of the invention.
- Fig. 22 shows a perspective view of an anode casing element having ridges attached to its interior surface, according to an alternative embodiment of the invention.
- Fig. 22A shows a perspective view of a Teflon ® ring for incorporation into an embodiment of the invention
- Fig. 23 shows an enlarged partial cross-section representation of a peripheral rim of the cathode casing element crimped around a peripheral rim of the anode casing element with vectors representing interacting forces, thereof.
- Fig. 24 shows a force vector representation of the peripheral rim of Fig. 23.
- Figs. 25A - 25B show partial cross-section representations of a single embodiment. The figures demonstrate the need for an engagement bend of an outer casing element to conform to shape of the inner casing element.
- Fig. 26 shows a cross-section representation of an alternative embodiment of the invention.
- the embodiment has a double bend to reduce the effects of "spring back.”
- Figs. 26A - 26B show enlarged partial cross-section representations of the embodiment of Fig. 26, according to an alternative embodiment of the invention.
- Fig. 27 shows a partial cross-section representation of another alternative embodiment of the invention.
- Figs. 28 - 29 show two partial cross-section representations of two alternative embodiments of the invention. The embodiments are designed to increase stresses in certain areas to limit electrolyte leakage.
- Figs. 30A and 3 OB show two enlarged cross-section representations of the embodiment of Fig. 8.
- Fig. 30C shows a cross-section representation of an air cathode according to one embodiment of the invention.
- Fig. 31 shows a cross-section representation of an air cathode according to an alternative embodiment of the invention.
- Fig. 32 shows a cross-section representation of a not yet crimped cathode casing element with internal components.
- the area dimensions of the internal components are sized to be slightly larger than the area dimensions that they are designed to occupy.
- This embodiment is an alternative embodiment of the invention.
- Fig. 33 shows a partial cross-section representation of the embodiment of Fig. 32 after assembly.
- Fig. 33A-C show cross-section representations of alternative embodiments
- Fig. 34 shows a cross-section representation of an alternative embodiment of the invention.
- the embodiment utilizes a snap-fitting strap to ensure that the casing elements remain engaged.
- Fig. 35 shows a cross-sectional representation of a sealed alkaline battery cell with a brass anode casing element.
- Fig. 36 shows a partial cross-sectional representative of a battery cell similar to the battery cell of Fig. 35.
- Fig. 40-43 demonstrate the performance of battery cells with an anode casing element made of brass as compared to cells made entirely of tri-clad.
- Fig. 44A-44C shows three views of an alternative embodiment of the anode casing element.
- Figs. 8 A and 8B show an assembled prism-shaped metal-air battery cell 100 having two major casing elements, an anode casing element 102 and a cathode casing element 104.
- the casing elements 102, 104 support and make up the overall structure of the battery cell 100 and houses the interior elements of the battery cell 100 from an outside, thereof.
- the casing elements 102, 104 are substantially rectangular tray-shaped casing elements with a respective major wall structure or base 110, 112, continuous side walls 114, 116 meeting at corners 106, 108, a bend portion between the base 110, 112 and the side walls 114, 116, and a peripheral edge 118, 120.
- the bend portion of the anode casing element 102 is a peripheral trough 142 and a peripheral rim 140
- the bend portion of the cathode casing element 104 is a peripheral ledge 132 and a peripheral basin 134.
- the internal components of the cell 100 including a metal anode 122, an air cathode 124, a separator 126 and a diffuser 128.
- An insulated grommet 130 separates the side walls 114, 116 of the casing elements 102, 104 and prevents the casing elements 102, 104 from contacting each other.
- the grommet 130 also protects the air cathode 124 from the anode casing element 102 and seals the casing elements 102, 104 together.
- An anode current collector (not shown) electrically connects the metal anode 122 to the anode casing element 102, and a cathode current collector (not shown) electrically connects the air cathode 124 to the cathode casing element 104.
- the casing elements 102, 104 are mutually engaged to each other and remain engaged by bending the side walls 116 of the cathode casing element 104 partially around the anode casing element 102, preferably by a crimping process.
- the assembly process creates a compressive stress in the grommet 130 and the casing elements 102, 104, which seals the battery cell 100.
- the stress is primarily derived from forces in the axial direction due to the shape of the casing elements 102, 104 during and after the assembly process is complete. This stress persists, at least partially, after the assembly process so that a seal is effectuated.
- the air cathode 124 may contain a layer or two of uncompressed Teflon® which further seals the air cathode 124 to the cathode casing element 104.
- the cathode casing element 104 of the battery cell 100 contains features that increase its strength and improve the reliability and manufacturability of the battery cell 100.
- the peripheral ledge 132 and the peripheral basin 134 increase the strength and rigidity of the casing element 104 and also provide reliability benefits described hereinafter.
- the ledge 132 and the basin 134 increase the strength and rigidity of the cathode casing element 104 by translating a portion of a load to the much stronger, rounded comers 108. This load can be due to external forces or resistance to internal pressure. Note that basin 134 helps to prevent collapse illustrated in Fig. 6, for example.
- a bending moment - as would be generated by a force F applied to the center of the span and resisted by fixed support points S - is resisted by the curves of the ledge 132 and the basin 134.
- the ledge 132 and the basin 134 translates a concentrated force applied in one area of the casing element 104 by spreading the force more evenly around the ledge 132 and the basin 134 areas, including areas near the comers 108.
- the casing element 104 subjected to a load along one of its long spanning walls, is able to resist deformation by fr- sferring part of the load to the rounded corners 108.
- the side walls 116 of the "uncrimped" cathode casing element 104 widens from the peripheral basin 134 to the edge 120.
- This outward flare may assist with the manufacture of the metal-air battery 100 by making it easier for the manufacturer to place the internal components into the cathode casing element 104.
- the flare helps guide the components during assembly and permits frill insertion of the parts without distortion of those parts. This feature is particularly advantageous when inserting the an air cathode 124 since the air cathode can be very delicate.
- the internal components of the battery cell 100 should be able to easily slide into the cathode casing element 104.
- the crimping or bending process may, although not necessarily, eliminate the flare, making the side walls 116 substantially perpendicular to the major surface 112 and the peripheral ledge 132.
- assembling the battery cell 100 requires the manufacturer to bend or crimp the cathode casing element 104 at least partly around the anode casing element 102.
- bending the edge 120 around the comers 106 of the anode casing element 102 may cause portions of the cathode casing element 104 to corrugate which may result in a poor electrolyte seal.
- the cathode casing element 104 can be made of a very soft or annealed metal at the portions that are prone to corrugation. In some instances a small degree of corrugation may be acceptable.
- the use of ductile material such as brass may also reduce the corrugation that may result during the assembly process.
- notches 136 are cut near the comers 108 of the cathode casing element 104 to reduce the amount of excess material when the edge 120 is bent. Excess material can corrugate and compromise the seal. In addition, if the excess material is compressed to its elastic phase, it can elongate and form an electrical bridge to the anode casing element 102, causing the battery cell 100 to short circuit. The notches 136 solve this problem by reducing the amount of excess material.
- Fig. 12B in another alternative embodiment, reduction of excess material to prevent corrugation and short circuiting can be accomplished by forcing the basin 134 downwardly at portions near the comers 108.
- the figure shows the effect very exaggeratedly. Creating depressions, such as by a "forcing" process, draws excess material from the walls 116 into the basin 134 and, in essence, shortens the height of the walls at the comers 108.
- the cathode casing element 104 can be bent to different degrees along its edge 120.
- the casing element 104 can be bent further along the side portions of the casing element and less along the comer portions.
- comer portions 139 of the cathode casing element 104 are not bent around the anode casing element 102 to the same degree as portions along the sides of the battery cell 100, making the edge 120 rises slightly around the comer portions 139.
- This solution reduces corrugation by reducing the amount of shortening deformation near the comer portions 139 while still adequately sealing the casing elements 102, 104 together.
- Figs. 12d(l) and 12d(2) show a partial cross-section representation of the side portions of the cell and Fig. 12d(2) shows a partial cross-section representation of the comer portions of the same cell.
- air access holes 138 on metal-air battery cells may be a source of electrolyte leakage.
- the base 112 of the cathode casing element 104 has a plurality of air access holes 138 that are sized and populated to ensure that the air cathode 124 has sufficient access to oxygen. Oxygen is needed by the battery cell 100 to generate current.
- Increasing the size of the air access holes may increase the supply of oxygen to the air cathode 124.
- larger air access holes 138 may also increase the likelihood that electrolyte will leak out through the air access holes 138 and may also increase the rate that the metal anode 122 desiccates.
- Larger air access holes 138 may permit electrolyte to freely pass through while smaller air access holes 138 may restrict the flow through the holes 138.
- the surface tension of a liquid or gel like electrolyte may prevent the electrolyte from passing through smaller sized air access holes 138.
- Air access holes 138 that have a diameter of 0.4 - 0.5 mm can be repeatedly punched in a metal casing having a thickness of 0.1 - 0.4 mm without undue maintenance of the punches. Smaller sized holes 138 were found to be more difficult to punch.
- a preferred approach in designing a cathode casing element 104 to limit excessive desiccation and electrolyte leakage while providing sufficient air access is through experimentation. Using an agreed upon and constant dimensions of the air holes 138, determine the electrical energy generated by an agreed upon and constant dimensions of a metal-air battery 10 when different cathode casing elements 104, having different but uniform distances between each air hole 138, are used.
- the density of the air holes 138 increases, the number of air holes 138 that can fit on the base 112 increases and the total current generated by the battery cell 100 should also increase. At some point, however, the total current will decrease or remain constant. This point occurs when the area supplied by each air hole 138 significantly overlaps the area supplied by an adjacent air hole 138. Further increasing the density of the air holes 138 may unnecessarily increase the rate by which the battery cell 100 desiccates without contributing significantly to the oxygen supply to the air cathode 124.
- the anode casing element 102 also contains features that increase its strength and improve the reliability of the battery cell 100. Referring now to Fig 13, the peripheral rim 140 and the peripheral trough 142 increase the strength and rigidity of the casing element 102, and do so in substantially the same way as the ledge 132 and the well 134 of the cathode casing element 104. The rim 140 and the trough 142 spread out a concentrated force to the round comers 106 of the anode casing element 102.
- the flare of the anode casing element 102 helps to insure that both casing walls 114, 116 cooperate to support the cell 100.
- the outward flare engages the base 112 of the cathode casing element 104 to ensure that the type of buckling illustrated in Fig. 6 does not occur.
- the outward flare can also improve the electrical connection between the cathode collector (not shown) and the cathode casing element 104 and also improve the effectiveness of the separator 126.
- the axial force from the assembling process causes the peripheral rim 144 of the anode casing element 102 to press against the separator 126 and the air cathode 124, via the grommet 130.
- the axial force also cause the sloping side walls 114 and the ends of the walls to deflect outwardly, which pushes the edges of the air cathode 124 and the separator 126 against the cathode casing element 104 and improves the electrical connection between the cathode current collector and the casing element 104.
- the cathode current collector (not shown) forms a better electrical connection with the casing element 104.
- the shape of the peripheral rim 144 provides increased reliability by protecting the grommet 130.
- the rim 144 directs the sharp edges of the peripheral edge 118 away from the portion of the grommet 130 that is prone to damage when an axial force pushes the rim 144 against the grommet 130 These axial forces exist when the battery cell 100 is assembled and even exist after assembly.
- the cutting and punching process that is performed to form the casing element 102 may form a sharp edge 118, and that edge 118 may damage the grommet 130 by digging into and shearing the grommet 130.
- the rim 144 is shaped so that the edge 118 does not dig into the grommet 130, but rather the smooth surfaces of the rim 144 press against the grommet 130, thereby distributing the axial forces over a larger area of contact.
- a rim 145 has a bend of approximately 180 degrees, which distances the edge 118 even further from the portion of the grommet most susceptible to damage.
- a rim 146 has a bend in the opposite direction, or inwardly.
- the cathode casing element 104 does not need to be shaped to accommodate the space occupied by an outward protrusion of the rim 146.
- the grommet 130 can be thinner and the anode casing element 102 can be sized to hold a larger quantity of the metal anode 122.
- a rim 147 is shaped to have two bends.
- the rim 147 provides the benefits of a tiiinner grommet 130 and a larger capacity anode casing element 102 as in the previous embodiment.
- the rim 147 through its multiple bends, provides increased strength and rigidity, making it less susceptible to collapsing.
- the rim 147 also protects against an undesired chemical reaction between the casing element 102 and the metal anode 122.
- a casing element made of a nickel-steel-copper triclad can react with a zinc anode to produce hydrogen or to introduce contaminant ions into the electrolyte.
- the nickel is normally coated to prevent the undesired chemical reaction.
- the nickel may become exposed at the edges 118 during the formation of the casing element 102.
- the rim 147 distances the edge 118 away from the metal anode 122.
- the edges are smooth and rounded so that they do not contain sharp edges.
- the base 110 of the anode casing element 102 has ridges 146 that run from the peripheral trough 142 on one side of the casing element 102 to the peripheral trough 142 on the opposite side.
- the base 112 of the cathode casing element 104 may also contain ridges, as well. These ridges 146 increase the rigidity of the base 110 and make the casing element 102 less susceptible to deformation under increased internal pressure or external forces.
- the ridges 146 of the anode casing element 102 provide increased strength by transferring external forces on the base 110 to the rim 140 and the trough 142. These ridges 146 may be formed at the same time the cathode casing element 104 is crimped over the anode casing element 102, via an appropriately designed crimping tool, h the alternative, the ridges 146 may be formed at the time the anode casing element 102 is formed through a stamping process. Cold forming ridges 146 on a thin, relatively flat metal surface, such as the major surface 110, creates ridges 146 on both sides of the metal surface and further increases the strength of the base 110. In an alternative embodiment shown in Fig.
- the base 110 of the anode casing element 102 contains one ridge 146 A with a radius of curvature R.
- the radius of curvature is comparatively small when compared to the length of the major surface.
- the preferred dimension of the radius of curvature is dependant on a number of factor including the dimensions and thickness of the casing element 102, the strength and ductility properties of the brass material, and the magnitude of the forces that the casing element 102 is to designed to resist.
- the ridges 146 also can form a hatched pattern across the base 110 although a hatched or criss-cross pattern may not provide the needed strength to resist certain types of internal or external forces.
- Other examples of ridges are illustrated in Figs. 20, 21, and 22.
- Figs. 20 and 21 show two alternative arrangements with ridges 148, 150.
- Fig. 22 shows an anode casing element 102 with ridges 152 attached to its inner surface.
- the ridges 152 are relatively thin so as to limit the space it occupies, thereby leaving more room for the metal anode.
- These ridges 152 also increase the strength of the side walls.
- the anode casing element 102 may also be coated on its interior or concave surface.
- Suitable coating materials include tin, indium and gold.
- the layer of tin separates the brass casing element 102 from the anode of the battery cell 100.
- the tin layer also electrically connects the electrically charged anode to the anode casing element 102 so that the casing element 102 can act as an electrode of the cell 100.
- the bend 43 is inherently strong. Deforming a cylindrical shaped element so that the edge is bent inwardly creates a very strong hoop that is resistant to extension. The bend 43 can then resist deformation and disengagement of the casing elements 42, 52 through its hoop strength. Also, as explained before, the battery cell 40 remains sealed due to the even distribution of forces around the circumference of the battery cell 40.
- button cells can be reproduced in prism-shaped cells.
- a similarly designed bend in a prism-shaped cell does not provide the cell with the same strength and rigidity qualities of a button cell. Bending the casing element over long straight sides can easily be straightened towards its original position.
- a bend of a mere 45 degrees is not particularly strong considering the lack of compression deformation described above, the dimensions of many types of battery cells, and the "spring back" effect of metal when it is bent.
- the bend 43 of the cathode casing element 42 springs back and the side wall 46 begins to flare outwardly, the two casing elements 42, 52 may becoming disengaged.
- Simply increasing the degree of bend does not solve all the problems since it can cause the edges 44 of the cathode casing element 42 to corrugate at the comers and become the source of electrolyte leakage.
- increasing the degree of bend may cause the cathode casing element 42 to contact the anode casing element 52 resulting in an short circuit.
- Nery thin button cells do not experience the effect of a thicker, bulging battery cell, which may cause the inner casing element to slide out of the C-shaped crimp, or alternatively, cause the crimp to open. Further, the C-shaped crimp occupies an excessive amount of space in the lateral direction, thereby reducing the main benefit of a prism-shaped cell.
- the cathode casing element 104 is bent or crimped over the peripheral rim 140 of the anode casing element 102, forming a bend 154. Due to the elasticity of metal, the cathode casing element 104 tends to spring back when bent.
- the bend 154 should be subjected to a high degree of strain.
- the side wall 116 also contains a bend 155 to accommodate the outward protrusion of the rim 144.
- the bend 154 prevents the casing elements 102, 104 from uncoupling. By bending or crimping the casing element 104 far enough so that a portion of the bend 154 extends towards the base 112, the bend 154 prevents the side walls of the cathode casing element 104 from uncoupling and the casing elements 102, 104 from disengaging.
- the protrusion of the rim 140 of the anode casing element 102 and the thickness of .the grommet 130 prevent the bend 154 from deflecting laterally. Essentially, the bend 154 "hooks" over the rim 140 to prevent the side wall 104 from being pushed out.
- the bending process can be accomplished by further crimping the peripheral basin 134 by a pinching process so that the outward flare of the side walls 116 is reduced or eliminated. Then, while pressing the anode casing element 102 against the cathode casing element 104, the cathode casing element 104 is crimped around the peripheral rim 140 by a similar pinching process. To reduce the negative effects due to elastic rebound when the cathode casing element 104 is crimped, the anode casing element 102 should be firmly pressed against the cathode casing element 104 and the grommet 130 should be compressed at positions 156 and 158.
- Compressing the grommet 130 while crimping the cathode casing element 104 improves the seal of the battery cell 100.
- the resiliency of the grommet 130 can fill any gaps between the casing elements 102, 104 and the grommet 130 that are created if the cathode casing element 104 springs back. Even after the cathode casing element 104 springs back, the grommet 130 is still at least partially compressed at positions 156 and 158 so that a tight seal is maintained at those points.
- the resiliency of the grommet 130 forms the seal.
- the grommet 130 is shaped so that an air filled void 131 is created between the seal near the cathode 156 and the seal near the edge of the cathode portion of the cell casing 158. Without a void 131, any electrolyte that has managed to work its way past the seal at position 156 may be assisted, through a capillary effect, with its migration to the seal at position 158.
- the void 131 reduces or eliminates this capillary effect by significantly enlarging the channel through which electrolyte can flow.
- the peripheral basin 134 can be even further crimped so that the side walls 116 of the cathode casing element 104 bow inwardly. Further bending may ensure that the casing element 104 does not peel back from the peripheral rim 140 when internal pressure builds up and the battery cell 100 begins to bulge. Overcrimping may also resist the tendency of the battery cell 100 to bulge at the side walls 114, 116 by compensating for increased pressure buildup. Further, such crimping may increase the interacting forces between the side walls 114, 116, thereby improving the effectiveness of the grommet 130 to seal the battery cell 100. Greater forces between the grommet 130 and the side walls 114, 116 may create a better seal.
- the resiliency of the grommet 130 also ensures that a seal is maintained between the air cathode 124 and the peripheral ledge 132.
- the air cathode 124 may contain a generally planar layer of uncompressed Teflon® on the side that faces the base 112.
- Uncompressed Teflon® is particularly suitable because of its gas permeability properties.
- Teflon® is not very resilient. The portion of the Teflon® layer that contacts the ledge 132 remains at least partially compressed if the axial forces disappear. Therefore, to ensure that the seal is maintained, the grommet 130 should continuously press the air cathode 124 against the ledge 132.
- the generally planar layer of uncompressed Teflon® is not a necessity and may be replaced with a flat, ring-shaped piece of Teflon®.
- a Teflon® ring 190 is placed on, and shaped to cover, the flat portions of the ledge 132.
- the Teflon® ring 190 can also be attached to the air cathode 124, such that the Teflon® ring 190 is positioned between the air cathode 124 and the ledge 132.
- the air cathode 124 can have a generally planar layer of uncompressed Teflon® and a Teflon® ring 190 attached to the planar layer. Two layers of Teflon® may ft-rther improve the seal between the air cathode 124 and the ledge 132. Also, the Teflon® ring 190 eliminates one layer of Teflon® between the air cathode 124 and the diffuser 128. Unnecessary layers of Teflon® can act as barriers between the air cathode 124 and the air access holes 138 and restrict the battery cell's 100 access to oxygen.
- the prism-shaped battery cell 100 of the present invention resists disengagement through substantially axial, interacting forces between the casing element 102, 104.
- the cross-section of the curvature of the bend 154 substantially conforms to the shape of the rim 140 so that the lateral or non-axial components of the interacting forces that portions of the casing element 104 exert near the bend 154 and the rim 140 substantially cancel each other out.
- the remaining axial components of the forces press the anode casing element 102 against the cathode casing element 104.
- the bend 154 exerts forces on the peripheral rim 140 represented by F j0 and F ⁇ .
- the lateral components of the forces F ⁇ 0X and F nx are substantially equal and opposite.
- the summation of the axial components of the forces F 10Y , F 11Y oppose the summation of the axial forces F 12 that the anode casing element 102 exerts on the cathode casing element 104.
- Figs. 25A and 25B illustrate the same battery cell under different internal pressure.
- the battery cell - which has a cathode casing element shaped to have a bend 172 and an edge 176 and an anode casing element shaped to have a rim 174 - may experience bulging when subjected to a high internal pressure.
- the side walls of the cathode casing element may flare outwardly as the rim 174 of the anode casing element works its way towards the edge 176 of the cathode casing element. This outward flare may cause the battery cell to bulge and possibly leak electrolyte.
- the casing elements 102, 104 remain engaged to each other through a severe bend feature, which in the example includes a first bend 168 of approximately 180 degrees and a second bend 170 of approximately 90 degrees.
- the advantage of this double ' bend feature is that the negative effects of spring back can be significantly reduced or eliminated.
- a slight elastic rebound of either of the two bends 168, 170 will not significantly lessen the force that the cathode casing element 104 exerts on the peripheral rim 140 of the anode casing element via the grommet 130.
- a severe bend feature which in the example includes a first bend 168 of approximately 180 degrees and a second bend 170 of approximately 90 degrees.
- the grommet 130 is compressed at the same time that the bend 154 is formed. Any spring back of the bend 154 must be absorbed by the resiliency of the grommet 130 or electrolyte may leak. In the present embodiment, a minor spring back of the bends 168, 170 has a much less detrimental effect on the seal of the battery cell because the clamping distance - which is measured from base to the contact point near the bend - does not significantly change. The likelihood of electrolyte leaking through a gap between the casing element is significantly reduced.
- the second bend 170 should be formed before the first bend 168.
- the trough 142 of the anode casing element 102 should also be of a shape to leave room for the cathode casing element 104 during the formation of the crimp 168.
- the cathode casing element 104 is bent to approximately 90 degrees. While this embodiment may lack some of the benefits of the bends of the embodiments of Figs. 8A and 26, this embodiment is particularly suitable for battery cells 100 that do not experience a high degree of internal pressure or external forces. The embodiment is much easier and less costly to manufacture and still provides resistance to forces which cause the casing elements to disengage.
- the casing elements 102, 104 prevent disengagement through a bend 185 of approximately 90 degrees and also through an adhesive attaching the grommet 130 to the casing elements 102, 104.
- the grommet 130 fills the gap between the casing elements 102, 104 so that the battery cell 100 is sealed and electrolyte does not leak.
- the grommet 130 is coated with a liquid or semi-liquid sealant to further improve the seal by filling the gaps between the grommet 130 and the side walls 114, 116 and by blocking the small channels in the casing elements 102, 104 caused by scratches on the surface of the side walls 114, 116.
- Tar has been found to be a particularly suitable substance. It is preferable that the substance be an electrically insulating substance so that a short circuit does not occur.
- the shape of the casing elements 102, 104 create areas where the interacting forces between the casing elements 102, 104 are more concentrated, thereby improving the sealing qualities of the grommet 130.
- the radius of the crimp 154 is greater than the radius of the rim 140 which concentrates the axial forces at approximately location 160.
- minor peripheral ridges or protrusions 162 create the same effect.
- a seal can also be improved through the addition of minor peripheral ridges or protrusions of the surface of the grommet 130.
- a diaper ring 162 can absorb the escaping electrolyte before it completely exits the battery cell 100.
- the diaper ring 162 is preferably located between the peripheral trough 142 of the anode casing element 102 and the crimp 154 or the edge 120 of the cathode casing element 104.
- an air cathode 64 is positioned near the base 48 of the cathode casing element 42 so that the air cathode 64 has access to oxygen via air holes (not shown) punched in the base 48.
- a cathode current collector (not shown) is embedded in the air cathode 64 and provides a means through which electric charge can flow. An edge 66 of the collector is exposed and contacts the cathode casing element 42, thereby electrically connecting the air cathode 64 to the cathode casing element 42.
- the prior art example illustrates the comer 50 of the cathode casing element 42 as being rounded.
- a battery cell with interior rounded comer is less reliable.
- the rounded comer 50 may force the air cathode 64 with the embedded cathode current collector (not shown) to bend and conform to the shape of the rounded comer 50.
- the edge 66 of the current collector is the means through which the air cathode 64 electrically connects to the cathode casing element 42, a bend may cause the battery cell 40 to electrically disconnect. It is preferred that the edge 66 directly contact, or even better, dig into the cathode casing element 42.
- Electrochemical Cells Made Therewith and numbered 5,662,717 teaches of using a cathode casing element with a relatively sharp interior comer.
- a sharp comer relates to an improvement of the structure, an added benefit is increased reliability.
- the edges of a cathode current collector can dig into and contact the sharp comer.
- a sharp interior comer also has its drawbacks. Sharp interior comers are difficult and expensive to manufacture. A relatively sharp die is usually required to form sharp interior comers, and sharp dies tend to dull very quickly. Constant sharpening and replacing is required.
- the cathode casing element 104 has features which improve reliability and lower costs.
- the edges of the air cathode 124 and the separator 126 press against the side walls 116 of the cathode casing element 104, thereby ensuring electrical connectivity is maintained between the casing element 104 and a cathode current collector 125 embedded in the air cathode 124.
- the side walls 116 be substantially perpendicular to the air cathode 124 and the cathode current collector 125. Since only the edges of the current collector 125 are exposed, a less than perpendicular contact may result in the air cathode 104 being electrically disconnected from the casing element 104.
- the shape and the size of the basin 134 and the ledge 132 ensure a substantially perpendicular contact. Unlike the prior art, which was discussed above and illustrated in Fig. 5, the present embodiment eliminates the likelihood that the air cathode 124 will bend and conform to the shape of round interior corners. Further, the embodiment eliminates the need for sharp comers, which can be expensive due to the repeated replacement and sharpening of dies used to make the sharp comers.
- Another feature of the invention relates to the size and shape of the air cathode 124 and the separator 126.
- the area dimensions of the air cathode 124 and the separator 126 can be slightly larger than the area dimension that the components are intended to occupy. The slightly larger size ensures that that edges of the components press against the side walls 116, thereby ensuring a tight seal by the separator 126 and electrical connectivity with the current collector 125.
- Fig. 30C exaggeratedly illustrates the size differences between a surface area representation 175 of the air cathode 124 before assembly and a surface area representation 177 of the area that the air cathode 124 is intended to occupy or "occupied representation".
- a length L 175 of the pre-assembly representation 175 is longer and a width W 175 is shorter than a length L 177 and width W 177 of the occupied representation 177, respectively.
- the length L 177 of the occupied dimension 177 is longer than its width W 177 , it is preferred that the length L 175 of the pre-assembly representation be longer than the length L, 77 of the occupied representation 177.
- the air cathode 124 it is preferred (though not necessary) for the air cathode 124 to have an area dimension that is longer than the corresponding area dimension of the occupied representation for that particular area dimension that is the longer of the two area dimensions. This configuration has been found to produce a better electrical connection with less rippling effects.
- Fig. 31 exaggeratedly illustrates an alternative embodiment where comer sections 191 of a surface area representation 193 of the pre-assembled current collector 127 and the air cathode 124 extend out from a surface area representation 195 of the "occupied representation".
- These comers sections of the current collector 127 are a means by which the current collector 127 contacts the casing element 104.
- FIG. 30A and 30B another feature of the basin 134 is that it can be used to catch electrolyte or adhesive that had managed to work its way around the separator 126.
- a peripheral diaper ring similar to the diaper ring 162 described above, can be placed in the recess of the basin 134 and absorb the electrolyte or adhesive before it can work its way out through the air access holes 138 of the cathode casing element 104.
- Figs. 32 and 33 showing an alternative embodiment, one of the area dimensions of the air cathode 124 and the separator 126 are larger that the corresponding area dimension of the occupied representation.
- Fig. 32 which shows the air cathode 124, the separator 126, and the cathode casing element 104 prior to the insertion of the anode casing element 102, the centers of the components 124, 126 bow away from the base 112 to form a gentle curve facing concave down.
- the components 124, 126 After insertion of the anode casing element 102, as illustrated in Fig. 33, the components 124, 126 become flattened and bent near their edges. The resiliency of the components 124, 126 ensure that the separator 126 adequately seals and that the cathode current collector 125 electrically connects to the casing element 104.
- a strap 166 resists any deformation and bulging of the battery cell 100.
- the strap 166 is snap fitted onto the battery cell 100. It is preferred that the strap 166 be made of an insulated and resilient material so that the strap does not cause the battery cell 100 to short circuit.
- the casing elements can contain a recess shaped to fit the strap 166 so that the strap 166 is at least partially embedded in the cathode and/or anode casing elements 102, 104. The recess can ensure that the strap 166 remains in place and may also make the battery cell easier to connect to the electronic device. Also, depending on the configuration of the battery cell 100, the strap 166 may eliminate the need for crimping the cathode casing element 104.
- a battery cell 200 has two casing elements 202, 204 for holding the internal components of the battery cell.
- the anode casing element 202 is made of brass and is in electrical communication with an anode 212 of the cell 200.
- the cathode casing element 204 is in electrical communication with a cathode 214 of the cell 200.
- the cathode 214 is a consumable oxider as contained in a sealed alkaline cell.
- the cathode casing element 204 and anode casing element 202 are electrically separated from each other by a grommet 216, and a separator 210 separates the anode 212 from the cathode 214.
- a single resilient strap 218 circumscribes and seals the battery cell 200 by pressing the casing elements 202, 204 against each other.
- the casing elements 202, 204 are shaped to prevent the lateral movement of the casing elements 202, 204 with respect to each other.
- a peripheral ridge 220 of the anode casing element 202 is shaped to couple with a peripheral ridge 222 of the cathode casing element 204.
- peripheral ridges 220, 222 of the embodiment of Fig. 35 are eliminated. Instead, relatively flat surfaces of the casing elements 202, 204 are pressed against each other and separation and lateral movement is resisted by the strap 218.
- the dimensions of the battery cell 100 play an important role in its ability to resist the internal and external forces that are placed on the anode casing elements 102 of the battery cell 100 both during operation and during assembly.
- a battery cell 102 with a relatively large major wall 112 and relatively short side walls 114 may be particularly weak at its major wall 112. When the anode expands, the battery cell 100 may bulge at its major walls 112,114. Furthermore, the center of the major wall 112 may deflect inwardly (or towards the major wall 114 of the cathode casing element 104) during the crimping process.
- the shape of the cathode casing element 104 when crimped, may force the major wall 112 of the anode casing element 102 to flex.
- a large major wall 114 may be particularly weak in resisting this force.
- An anode casing element 102 with a relatively small major wall 112 and tall side walls 114 may be particularly weak at its side walls 114.
- the crimping process bends the cathode casing element 104 around the anode casing element 102, and the side walls 114 may experience a large portion of the crimping forces. High side walls 114 may not be able to adequately resist these forces but instead bend or even collapse.
- the brass anode casing element 102 of a rectilinear battery cell has a thickness of 0.25 mm.
- a ratio of cell wall height to outer surface area of the major wall 112 is preferably within the range of 0.04 to 0.0002 and more preferable closer to 0.003.
- the use of anode casing element 102 with a thickness in the range of 0.1 mm and 0.5 mm does not drastically modify of the preferred range of the ratio. Examples
- Rectangular-shaped cells having approximately the same dimensions but made from different materials, were assembled, formed, and tested to determine the effect, if any, the use of a brass as an anode casing element has on the performance of the cells.
- the anode casing elements tested in this experiment each had a thickness of 0.25 mm, a major surface with a surface area of 1242 mm 2 , and a cell wall height of 4.3 mm.
- Four cells of the same type were electrically connected in series and tested under conditions similar to conditions experienced when powering a cellular phone. Each set of four cells powered a device demanding 2 amp for 0.4 milliseconds followed by 0.2 amps for 3.6 milliseconds for each 4 millisecond interval.
- FIG. 40 shows a graph of output voltage versus time for four electrically connected cells having an anode casing element made of a tri-clad of nickel, stainless steel, and copper.
- the cells were tested between 11 to 21 days after assembly.
- Each of the four triclad cells exhibited a potential of approximately 1.01 volts with a capacity of approximately 3.6 amp hours.
- the data lines represent the potential of the each of the cells during the intervals of higher demand (2 amps) and during the intervals of lower demand (0.2 amps).
- FIG. 41 shows a graph for four cells having an anode casing element made of a medium hard brass. The cells were tested under conditions similar to the conditions of the tri-clad cells. Each of the four cells exhibited a potential of approximately 1.02 volts with a capacity of approximately 3.55 amp hours. As is evident from the results, the cells having the brass anode casing element performed almost as well as the tri-clad battery cells.
- FIG. 42 shows a graph for four cells having an anode casing element made of a medium hard brass.
- the cells were stored for 14 days at temperature of 71°C before testing.
- the results are comparable with the previous results, namely each one of the four cells exhibited a potential of approximately 0.98 volts with a capacity of approximately 3.4 amp hours.
- FIG. 43 shows a graphs for four cells having a brass anode casing element with a tin coating on its interior surface.
- the cells were subjected to the same conditions as the battery cells of the graph of FIG. 42. '
- the use of brass resulted in little, if any, negative effects.
- the cells exhibited a potential of approximately 0.99 volts with a capacity of approximately 3.4 amp hours.
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2002214191A AU2002214191A1 (en) | 2000-11-13 | 2001-11-13 | Structure for a metal-air battery cell having a brass casing element |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US71103500A | 2000-11-13 | 2000-11-13 | |
US09/711,035 | 2000-11-13 |
Publications (2)
Publication Number | Publication Date |
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WO2002039515A2 true WO2002039515A2 (en) | 2002-05-16 |
WO2002039515A3 WO2002039515A3 (en) | 2002-08-01 |
Family
ID=24856527
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/IB2001/002124 WO2002039515A2 (en) | 2000-11-13 | 2001-11-13 | Structure for a metal-air battery cell having a brass casing element |
Country Status (2)
Country | Link |
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AU (1) | AU2002214191A1 (en) |
WO (1) | WO2002039515A2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3114716A4 (en) * | 2014-03-06 | 2017-07-26 | UniCell LLC | Battery cells and arrangements |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2936781A1 (en) * | 1979-09-12 | 1981-04-02 | Varta Batterie Ag, 3000 Hannover | GALVANIC ELEMENT |
US5306580A (en) * | 1992-03-09 | 1994-04-26 | Eveready Battery Company, Inc. | Electrochemical cell having a coated cup-shaped terminal |
US5662717A (en) * | 1995-05-05 | 1997-09-02 | Rayovac Corporation | Metal-air cathode can having reduced corner radius and electrochemical cells made therewith |
WO2000036668A1 (en) * | 1998-12-15 | 2000-06-22 | Electric Fuel Limited | Sealing features in metal-air battery cells for the prevention of electrolyte leakage |
-
2001
- 2001-11-13 WO PCT/IB2001/002124 patent/WO2002039515A2/en not_active Application Discontinuation
- 2001-11-13 AU AU2002214191A patent/AU2002214191A1/en not_active Abandoned
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2936781A1 (en) * | 1979-09-12 | 1981-04-02 | Varta Batterie Ag, 3000 Hannover | GALVANIC ELEMENT |
US5306580A (en) * | 1992-03-09 | 1994-04-26 | Eveready Battery Company, Inc. | Electrochemical cell having a coated cup-shaped terminal |
US5662717A (en) * | 1995-05-05 | 1997-09-02 | Rayovac Corporation | Metal-air cathode can having reduced corner radius and electrochemical cells made therewith |
WO2000036668A1 (en) * | 1998-12-15 | 2000-06-22 | Electric Fuel Limited | Sealing features in metal-air battery cells for the prevention of electrolyte leakage |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3114716A4 (en) * | 2014-03-06 | 2017-07-26 | UniCell LLC | Battery cells and arrangements |
Also Published As
Publication number | Publication date |
---|---|
AU2002214191A1 (en) | 2002-05-21 |
WO2002039515A3 (en) | 2002-08-01 |
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