EP1859504A2 - Procede de fabrication d'accumulateurs au nickel-zinc - Google Patents

Procede de fabrication d'accumulateurs au nickel-zinc

Info

Publication number
EP1859504A2
EP1859504A2 EP06736671A EP06736671A EP1859504A2 EP 1859504 A2 EP1859504 A2 EP 1859504A2 EP 06736671 A EP06736671 A EP 06736671A EP 06736671 A EP06736671 A EP 06736671A EP 1859504 A2 EP1859504 A2 EP 1859504A2
Authority
EP
European Patent Office
Prior art keywords
cell
zinc
internal terminal
negative electrode
electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP06736671A
Other languages
German (de)
English (en)
Inventor
Jeffrey Phillips
Jason Zhao
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
PowerGenix Systems Inc
Original Assignee
PowerGenix Systems Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by PowerGenix Systems Inc filed Critical PowerGenix Systems Inc
Publication of EP1859504A2 publication Critical patent/EP1859504A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/538—Connection of several leads or tabs of wound or folded electrode stacks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/24—Alkaline accumulators
    • H01M10/28—Construction or manufacture
    • H01M10/286—Cells or batteries with wound or folded electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/24—Alkaline accumulators
    • H01M10/28—Construction or manufacture
    • H01M10/288—Processes for forming or storing electrodes in the battery container
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/24—Alkaline accumulators
    • H01M10/30—Nickel accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/44—Methods for charging or discharging
    • H01M10/446—Initial charging measures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0438—Processes of manufacture in general by electrochemical processing
    • H01M4/044—Activating, forming or electrochemical attack of the supporting material
    • H01M4/0445—Forming after manufacture of the electrode, e.g. first charge, cycling
    • H01M4/0447—Forming after manufacture of the electrode, e.g. first charge, cycling of complete cells or cells stacks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0473—Filling tube-or pockets type electrodes; Applying active mass in cup-shaped terminals
    • H01M4/0478—Filling tube-or pockets type electrodes; Applying active mass in cup-shaped terminals with dispersions, suspensions or pastes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0473—Filling tube-or pockets type electrodes; Applying active mass in cup-shaped terminals
    • H01M4/048—Filling tube-or pockets type electrodes; Applying active mass in cup-shaped terminals with dry powder
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/24—Electrodes for alkaline accumulators
    • H01M4/244—Zinc electrodes
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/24—Electrodes for alkaline accumulators
    • H01M4/26—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/24—Electrodes for alkaline accumulators
    • H01M4/32—Nickel oxide or hydroxide electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H01M4/623—Binders being polymers fluorinated polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H01M4/72—Grids
    • H01M4/74—Meshes or woven material; Expanded metal
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H01M4/80—Porous plates, e.g. sintered carriers
    • H01M4/808—Foamed, spongy materials
    • 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/423—Polyamide resins
    • H—ELECTRICITY
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    • 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H—ELECTRICITY
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    • 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
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/533—Electrode connections inside a battery casing characterised by the shape of the leads or tabs
    • 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
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to the rechargeable battery arts and, more particularly to the manufacture of nickel zinc rechargeable battery cells.
  • Rechargeable power sources have various benefits over non-rechargeable sources.
  • the use of non-rechargeable power sources raises growing environmental concerns with respect to hazardous waste disposal and remediation, hi light of the proliferation of portable devices, the number of non-rechargeable power sources needed to use those devices would be staggering.
  • Rechargeable power sources allow a battery cell to be used repeatedly thus reducing the introduction of hazardous waste products into the environment.
  • rechargeable power sources allow the conservation of the metal and chemical resources that would otherwise be spent in non-rechargeable power sources.
  • the use of rechargeable power sources encourages and expands continuing conservation efforts that are necessary for a growing population to embrace.
  • the benefits of rechargeable power sources are many, they are not without costs.
  • NiCad batteries commonly used in industrial and household appliances such as cordless phones, power tools and laptop computers, are one of a number of products that pose a potential environmental risk when disposed of incorrectly.
  • the batteries contain both Nickel and Cadmium, the most toxic component, and can cause health problems when not disposed of properly. They are both heavy metals and can also adversely affect the environment during recycling and disposal, (http://www.epa.nsw.gov.au/media/0403/eprbatteries.htm) [0005] Because of the hazardous nature of some of the commonly used materials for conventional rechargeable power sources, it would be desirable to manufacture a rechargeable power source that reduces the quantity of any potentially hazardous materials.
  • the present invention accomplishes the advantages described above by employing a nickel-cadmium type manufacturing process with certain important variations that allow for replacement of the cadmium negative electrode with a less deleterious negative electrode, such as an electrode fabricated from zinc or a zinc compound such as zinc oxide or calcium zincate.
  • a nickel-cadmium type manufacturing process with certain important variations that allow for replacement of the cadmium negative electrode with a less deleterious negative electrode, such as an electrode fabricated from zinc or a zinc compound such as zinc oxide or calcium zincate.
  • Various methods of manufacturing a cadmium-free power cell are described herein. The methods employ high volume lines for nickel and zinc electrode fabrication. As part of the manufacturing process, slurries, pastes, or dry powders of negative and positive electrode materials are continuously coated onto a carrier sheet.
  • the positive electrode material preferably has a composition similar to that employed to fabricate the nickel electrode in a conventional nickel-cadmium battery, although there may be some important optimizations for the nickel zinc battery system.
  • the negative electrode preferably employs zinc oxide and zinc metal or an alloy thereof as an electrochemically active material.
  • the negative electrode includes other materials such as bismuth oxide, indium oxide, and/or aluminum oxide.
  • the carrier for the negative electrode (which serves as a current collector) should be electrochemically compatible with the negative electrode materials.
  • the carrier material is preferably copper or an alloy of copper in the form of a perforated sheet or an expanded metal.
  • the negative electrode materials include dispersants to minimize agglomeration of zinc oxide particles, as agglomeration has been found to adversely affect the performance of nickel zinc cells
  • the methods employ multiple sheets (e.g., four) of separator material that separate the electrodes and minimize formation of zinc dendrites.
  • suitable separator materials include nylon sheets and microporous polyolef ⁇ n sheets.
  • the fabrication methods of this invention preferably make use of a high conductivity electrolyte that discourages dendritic growth in the zinc electrode.
  • the fabrication methods produce cells having a zinc negative electrode, yet they utilize certain production techniques heretofore reserved for other cell types.
  • existing nickel cadmium production lines may be utilized with minor modifications to accommodate the methods described herein.
  • the method employs the following sequence: coating positive and electrode current collector sheets with pastes or slurries of positive and negative electrode materials, drying and compressing the nascent electrode sheets, cutting and cleaning the sheets, and forming a "jelly roll" cell assembly from the cut electrode sheets and interleaved microporous separator sheets.
  • the methods described will find particular use in an all ready well-defined and mature manufacturing base.
  • Electrodes are disclosed to increase the efficiency of the rechargeable power cells by reversing the polarity of the cell such that he terminals are reversed in comparison to conventional methods of manufacture.
  • Certain embodiments employ dry processes in which relatively dry powders or granular mixtures of the electrode components are employed in place of slurries or pastes.
  • the electrode compositions employed in these dry processes need not include dispersants or other additives normally provided to improve the consistency of a slurry or paste.
  • Certain dry processing methods of manufacturing a rechargeable power cell may be characterized by the following sequence of operations: (a) applying a zinc negative electrode material to a first conductive carrier to form a first electrode sheet; (b) applying a nickel positive electrode material in a substantially dry state to a second conductive carrier to form a second electrode sheet; (c) disposing at least one separator sheet between the first electrode sheet and the second electrode sheet such that the first electrode and the second electrode sheets and the at least one separator sheet form are layered to form a cell assembly; and (d) winding or folding the cell assembly to form a three-dimensional structure having a form factor generally corresponding with that of the rechargeable power cell.
  • the negative electrode material may be applied to the first conductive carrier in a substantially dry state. Alternatively, it may be applied as a paste or slurry.
  • the rechargeable power cell may have any form factor including various forms of cylindrical and prismatic cells.
  • the nickel positive electrode material may be produced substantially free of dispersant and organic pasting aids.
  • the nickel positive electrode material will include a binder such as a fluorinated polyolefin.
  • the binder is present in the nickel positive electrode material at a level of between about 0.1 and 5 percent by weight.
  • the positive electrode material includes a nickel hydroxide and/or oxyhydroxide, a zinc oxide, a cobalt oxide, and a binder.
  • the negative electrode material is comprised of a zinc oxide, zinc or a zinc alloy, a bismuth oxide, and an aluminum oxide.
  • the negative electrode may also include a binder and/or a dispersant, which reduces agglomeration of particles.
  • the negative electrode has a low carbonate content; e.g., it may employ a zinc oxide having at most about 1% by weight carbonate. Carbonate may also be driven off by heating the negative electrode to a temperature of at least about 200 C. Such heating may have other beneficial effects.
  • the first conductive carrier is made from copper or an alloy of copper.
  • the first conductive carrier may include perforated copper or an alloy of copper or expanded copper or an alloy of copper, hi certain embodiments, the second conductive carrier is made from nickel such as a sheet of nickel foam.
  • the method also includes the following operations: (e) attaching a first internal terminal with a first end of the cell assembly such that only the negative electrode is in electrical communication with the first internal terminal; (f) attaching a second internal terminal with a second end of the cell assembly such that only the positive electrode is in electrical communication with the second internal terminal; (g) inserting the cell assembly into a retaining vessel; (h) filling the retaining vessel containing the cell assembly with an electrolyte; and (i) sealing the retaining vessel such that the electrolyte and the cell assembly is substantially isolated from the environment.
  • a variant or species of this method involves attaching a cell cap terminal to the first internal terminal and inserting the cell assembly into a retaining vessel and attaching the second internal terminal to the retaining vessel, such that the cell has a negative cap.
  • the method may also include the following: initially charging the rechargeable power cell according to a defined charging curve; and individually testing the rechargeable power cell such that the rechargeable power cell is grouped by charge/discharge similarities.
  • Another aspect of the invention pertains manufacturing methods characterized by the following operations: (a) applying a zinc negative electrode material to a first conductive carrier to form a first electrode sheet; (b) applying a nickel positive electrode material to a second conductive carrier to form a second electrode sheet; (c) disposing at least one separator sheet between the first electrode sheet and the second electrode sheet such that the first electrode and the second electrode sheets and the at least one separator sheet form are layered to form a cell assembly; (d) winding or folding the cell assembly to form a three-dimensional structure having a form factor generally corresponding with that of the rechargeable power cell; and (e) compression bonding a first internal terminal to a first end of the cell assembly such that only the negative electrode is in electrical communication with the first internal terminal.
  • the bonding may also be accomplished by soldering a first internal terminal to a first end of the cell assembly such that only the negative electrode is in electrical communication with the first internal terminal, hi this approach, prior to the soldering, the first internal terminal may be provided with solder coating.
  • various additional features may be associated with the methods. These include all those stated above for the dry processing procedure.
  • the method may employ internal terminals that take the form of a perforated disk, a slotted disk, or an H-shaped structure, hi certain embodiments, the first internal terminal is maintained in compression with the first end of the cell assembly by a downward force provided by a cell cap in a fully assembled rechargeable power cell. Such force may be provided by an elastomeric member or a spring device interposed between the cell cap and the internal terminal.
  • FIG. 1 is a diagrammatic representation of the process flow of an embodiment of the present invention.
  • FIG. 2 is a further diagrammatic representation of the process flow of an embodiment of the present invention.
  • FIG. 3 is a graphical cross-sectional representation of the cathode and anode prior to winding.
  • FIG. 4a is a graphical representation of a reverse polarity power cell sub assembly embodiment.
  • FIG. 4b is a graphical cross-sectional representation of a reverse polarity power cell sub assembly embodiment.
  • the present invention relates generally to techniques for the manufacture of nickel-zinc rechargeable battery cells using techniques similar to generally accepted production techniques for nickel-cadmium rechargeable power cells.
  • Embodiments of this aspect of the invention are discussed below with reference to Figs. l-4b. However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes as the invention extends beyond these limited embodiments.
  • FIG. 1 presents a diagrammatic representation of a manufacturing process flow for an embodiment of the present invention.
  • the process includes two separate paths, one for fabricating a negative electrode sheet and the other for fabricating a positive electrode sheet.
  • these two paths converge when the separate negative and positive electrodes are assembled into a single cell.
  • the process steps of these two paths are performed in parallel, within a single plant, so that the electrodes can be continuously formed as sheets that are then continuously combined in the process of forming nickel zinc cells in accordance with this invention.
  • Blocks 101 and 121 depict example starting materials for the positive and negative electrodes. These blocks represent the fact that the manufacturing process must begin by providing the requisite starting materials for creating electrodes. In addition to the raw electrode formulation materials, the process will also require electrode carrier sheets (comprised of conductive material that ultimately serves as the current collectors in the assembled cells) as well as separator sheets for separating the positive and negative electrodes in the assembled cells, electrolyte, water to form electrode pastes or slurries if these are employed in the process, and cell packaging materials (e.g., disk terminals, a cell can, etc.).
  • electrode carrier sheets compact of conductive material that ultimately serves as the current collectors in the assembled cells
  • separator sheets for separating the positive and negative electrodes in the assembled cells
  • electrolyte electrolyte
  • water electrolyte
  • water electrolyte
  • cell packaging materials e.g., disk terminals, a cell can, etc.
  • negative electrode materials (101) include zinc metal, ZnO, Bi 2 O 3 , Al 2 O 3 , HEC, and dispersant. Indium oxide is also included in some embodiments.
  • Various other formulations are possible, including those that employ other forms of zinc, such as calcium zincate or precursors thereof (e.g., calcium oxide and zinc oxide).
  • Other electrode formulations include various inorganic fluorides, inorganic fibers such as alumina-silica fibers, and organic fibers such as cotton flock etc. Still others employ no HEC, dispersant or other organic material.
  • the invention is generally directed to methods of manufacturing nickel zinc batteries.
  • the negative electrode materials are based on zinc and zinc compounds, which are significantly less hazardous than the more commonly used cadmium compounds.
  • the EPA has classified zinc and zinc compounds in Group D indicating inadequate evidence as to its carcinogenic potential (U.S. EPA, 1995a).
  • the International Agency for Research on Cancer (IARC) has not classified zinc as to its carcinogenic potential (IARC, 1987a).
  • IARC International Agency for Research on Cancer
  • epidemiological evidence strongly supports an association between cadmium exposure and neoplasia, including respiratory and renal cancers (ARB, 1986c).
  • zinc oxide is a suitable electrochemically active material for use in the negative electrode.
  • Other zinc compounds having may be utilized as well.
  • calcium zincate (CaZn(OH) 4 ) may be used as a starting material in place of ZnO. It can be appreciated that producing calcium zincate can comprise potentially damaging exothermic reaction.
  • the size of the zinc metal or alloy particles is relatively small; e.g., less than about 50 microns average diameter; more preferably less than about 45 microns average diameter; and even more preferably less than about 40 microns average diameter.
  • the zinc material has a particle size distribution characterized in that 92% by weight of the material has a particle size of less than 45 microns and 8% by weight of the material has a particle size of greater than 45 microns.
  • Various alloying elements may be employed in the zinc alloys. Examples include indium and bismuth, with lead and iron also being suitable in some cases.
  • the indium and/or bismuth concentration does not exceed 1% of the total alloy mass, hi some embodiments, the alloy contains up to about 500 ppm indium and up to about 500 ppm bismuth. In some embodiments, the alloy may contain up to about 25 ppm lead and/or up to about 5 ppm iron. [0030] It has been found that a high temperature "burn out" procedure can improve the high rate performance of the resulting zinc electrode.
  • zinc oxide is heated to a temperature of between about 200 and 400 0 C, preferably between about 300 0 C and 38O 0 C (e.g., about 32O 0 C) for a period of between about 0.5 and 2 hours in an inert atmosphere or under vacuum (to limit oxidation of underlying copper current collectors).
  • the burn out procedure may remove dispersion agents and other organic materials believed to have a detrimental effect on high rate discharge of zinc electrodes.
  • the burn out procedure may remove carbonate, which may impede high rate discharge. It may reduce the conductivity of the electrolyte by, possibly, depleting hydroxide from the electrolyte and/or reducing the transport capability of the electrolyte.
  • the zinc oxide used to manufacture negative electrodes contains not greater than about 1 percent by weight of carbonate. It has been found that zinc metal components can withstand oxidation during the burn out procedure. Only a relatively small percentage of the zinc is converted to oxide during burn out during exposure to the atmosphere.
  • the zinc electrode is formed from a slurry or paste of zinc oxide and other electrode materials.
  • the zinc electrode is formed by a dry process, in which the electrode components are provided as a powdered mixture that is compressed on current collector or other carrier. As will be explained more fully below, the dry process may not require a dispersant or other organic material that can negatively impact performance.
  • the negative electrode mixture may include other materials that facilitate certain processes within the electrode such as ion transport, electron transport, wetting, porosity, structural integrity, active material solubility, etc. hi wet processes, other additives control the consistency for flow and other process-relevant properties of the slurry or paste itself.
  • the negative electrode slurry includes zinc alloy, bismuth oxide, aluminum oxide, hydroxyethyl cellulose (HEC), and a dispersant.
  • Hydroxyethyl cellulose (HEC) may be used to control the consistency of the slurry or paste of negative electrode materials.
  • HEC is a nonionic, water-soluble polymer that can thicken, suspend, bind, emulsify, form films, stabilize, disperse, retain water, and provide protective colloid action. It is readily soluble in hot or cold water and can be used to prepare solutions with a wide range of viscosities. Also, it has outstanding tolerance for dissolved electrolytes. Hence, HEC or other material with related properties is used in certain embodiments to force the negative electrode materials (in its paste form) to retain water. [0034] In one approach to forming a negative electrode slurry, two separate mixtures are produced and then combined to form the slurry. The first mixture comprises water and HEC (or other suitable material) and the second mixture comprises water and pre-sieved solids (e.g., zinc metal or zinc alloy, ZnO, AI2O3,
  • a dispersant to minimize agglomeration of low carbonate zinc oxide particles.
  • a dispersant modifies the surface properties of particles to facilitate dispersal throughout a slurry or other suspension.
  • Many dispersants are conventional surfactants or variations thereof tailored for the surface properties of particular particles to be dispersed.
  • zinc oxide is widely used in the paint industry, various dispersants for the oxide have been developed.
  • the negative electrode materials (101) are combined as described above to form a water-based slurry (103) and continuously applied to a conductive carrier sheet (151) as a slurry coat (105). It can be appreciated by one skilled in the art that the material may also be made into a paste and continuously applied via a paste head as in step 125 for the formation of the negative electrode.
  • the paste head applies negative electrode paste mix at a pressure of approximately 3 psi (pounds per square inch) to both sides of the carrier sheet.
  • a conventional slurry coating apparatus may be used, hi such apparatus, a continuous supply of slurry is provided to a chamber through which the carrier sheet passes.
  • the zinc electrode components are provided as a dry mixture.
  • these embodiments do not employ a slurry, paste or other wet composition, hi a dry mixture, the electrode components are provided as a powder or granular mixture that is relatively free of water or other liquid medium.
  • the electrode mixture will not flow in the manner of a paste or slurry and therefore will not be delivered via a paste head or related mechanism.
  • Dry processing is amenable to electrode mixtures employing metal additives such as zinc or zinc alloys, which can effervesce and negatively impact the consistency of a paste or slurry. Further, dry processing does not require use of certain organic materials such as dispersants and paste consistency additives, e.g., HEC. As mentioned above, these additives can negatively impact the performance of nickel-zinc cells.
  • the zinc electrode mixture employed in a dry process includes a source of electrochemically active zinc and an oxide such as aluminum oxide, bismuth oxide, and/or indium oxide.
  • oxide such as aluminum oxide, bismuth oxide, and/or indium oxide.
  • Other additives many include various inorganic fluorides, inorganic fibers such as alumina-silica fibers, and organic fibers such as cotton flock etc.
  • the source of electrochemically active zinc may be zinc oxide, zinc metal, alloys of zinc metal, calcium zincate or precursors thereof (e.g., calcium oxide and zinc oxide), partially oxidized zinc metal, and combinations thereof.
  • examples of alloying elements include indium and bismuth.
  • One particular embodiment employs a zinc metal or zinc metal alloy powder that has been partially oxidized to zinc oxide. The resulting partially oxidized metal is combined with an oxide and a suitable binder such as dry polytetrafluoroethylene (P.T.F.E.) powder as described above and applied to the negative electrode carrier material.
  • the dry powder zinc process involves feeding the powder at a controlled rate into compression rollers together with a three-dimensional electrochemically compatible substrate such as reticulated copper foam or expanded copper metal such that the powder is retained and compressed to the appropriate porosity.
  • a three-dimensional electrochemically compatible substrate such as reticulated copper foam or expanded copper metal such that the powder is retained and compressed to the appropriate porosity.
  • carrier materials may be used to form the positive electrode including, but not limited to, nickel, nickel plated steel, silver, and the like.
  • the carrier sheet serves as the current collector for the negative electrode in the finished nickel zinc cell. Copper and copper alloys are particularly preferred materials for the carrier sheet given copper's low resistivity, relatively low price, and electrochemical compatibility with the zinc electrode.
  • nickel plated steel is the carrier of choice for the cadmium electrode in commercial nickel cadmium cells.
  • the carrier sheet can be provided in various structural forms including a perforated metal sheet, an expanded metal, and a metal foam. Among the criteria employed to select a particular structural form are cost, ease of coating, and ability to facilitate electron transport between the electrochemically active electrode material and the current collector. In a preferred embodiment, the thickness of the carrier is between about 2 and 5 mils for perforated sheet but may be between 2 and 20 mils for expanded metal. Metal foam substrates may be between 15 and 60 mils. [0045] Once the negative electrode is coated, it is dried (107) in the case of a wet process to drive off excess water used as a delivery medium for the electrode material.
  • a thermal drier employing flowing air or nitrogen may be employed for this purpose.
  • the resulting negative electrode is then compressed (109) using a roller or other appropriate compression mechanism.
  • compression brings the electrode to a uniform thickness so that manufacturing tolerances may be maintained.
  • Compression also brings the negative electrode to a desired porosity. It can be appreciated that porosity controls the transport properties of ions between electrolyte and electrode. Porosity also dictates the active surface area and hence the current density of the negative electrode.
  • the post-compression thickness of the negative electrode is between about 10 and 40 mils (e.g., about 20 mils) and the porosity is between about 40 and 65 %.
  • the carrier sheet typically has a width significantly greater than that required for a single battery cell; e.g., the width may be on the order of one yard. Therefore, the negative electrode is cut to a width conforming to end-product specific tolerances (e.g., approximately 1.25 inches for a sub C size cell for example). A portion of the cut negative electrode may be "cleaned" prior to further assembly, hi particular, a strip of the negative electrode material along the edgewise length of the negative electrode is removed. The cleaned strip facilitates the attachment of a terminal to the negative electrode current collector at a further step 203 by exposing the underlying current collector metal.
  • the positive electrode may be formed. Beginning at an initial step 121, positive electrode materials are provided to form the positive electrode, hi an example embodiment employed in a wet process and as shown in FIG.
  • the positive electrode materials (121) comprising nickel hydroxide (Ni(0H)2), zinc oxide, cobalt oxide (CoO), nickel metal, optionally cobalt metal, and optionally a flow control agent such as carboxymethyl cellulose (CMC) are provided, hi a preferred embodiment, at least some of the zinc oxide and cobalt oxide are provided with the nickel hydroxide in a chemical mixture, whereby individual particles contain nickel hydroxide, zinc oxide and cobalt oxide.
  • Such premixed materials may be prepared by co-precipitation of the individual components and may be acquired in a commercially available formula from commonly known vendors such as International Nickel Corporation, and Tanaka. These materials prevent leaching by locking the oxides into the insoluble nickel matrix.
  • Co-precipitation also apparently helps charge transfer efficiency by creating conductive channels through the positive electrode materials.
  • the zinc oxide and cobalt oxide are each present in the co-precipitated material in concentrations of about 2-3% by weight for the zinc and about 2-6% for the cobalt oxide.
  • the positive electrode materials may additionally include chemically pure cobalt and nickel metal.
  • cobalt metal is employed in the positive electrode, it is preferably present in a concentration of between about 1% to 10% by weight. This concentration range is appropriate for a wide range of discharge rates (e.g., about 0.001 to 0.4 Amperes/cm of zinc electrode surface area).
  • the concentration of cobalt metal is between about 4-10% by weight in the positive electrode. In a typical low rate application, the concentration of cobalt metal is between about 1-5% by weight, and the discharge is conducted at about 0.001 to 0.01 Amperes/cm 2 of zinc electrode surface area.
  • cobalt oxide may be added to the material to enhance conductivity at operation 121.
  • the starting materials include little or no additional cobalt oxide. Note that in commercial nickel cadmium cells, free cobalt oxide is commonly employed in the positive electrode mixture.
  • a positive electrode paste is formed from two separate mixtures: one that includes CMC (carboxymethylcellulose) and water and another that includes water and the co-precipitated nickel hydroxide — cobalt oxide - zinc oxide, nickel metal, and relatively pure cobalt oxide. These two mixtures are then combined to form the positive electrode paste. Note that the CMC is included to improve flow characteristics for the resulting paste at step 123.
  • CMC carboxymethylcellulose
  • a few positive electrode compositions are described in the following documents, each of which is incorporated herein by reference: PCT Publication No. WO 02/039534 (J. Phillips) (co-precipitated Ni(OH) 2 , CoO and finely divided cobalt metal) and US Patent Application No.
  • the paste is continuously applied to a positive electrode carrier sheet via a paste head.
  • a paste head any of a number of carrier metals may be used to form the negative electrode so long as they meet appropriate design criteria such as low cost, high conductivity, electrochemical compatibility with the positive electrode, and good contact with the electrochemically active material. Examples include, but not limited to, nickel and nickel-plated stainless steel.
  • the carrier metal may possess one of various structural forms including perforated metal, expanded metal, sintered metal, metal foam and metal-coated polymer materials.
  • the carrier is a nickel metal foam formed by, for example, pyrolyzing a urethane foam on which nickel was electrolytically deposited.
  • the thickness of the foam positive electrode carrier after undergoing a prepress to ensure thickness uniformity is between about 15 and 60 mils, for example.
  • the positive electrode can be prepared using a dry process. In this approach, the CMC and certain other organics are not used. Note that in some embodiments, it is not feasible burn off organics from the positive electrode mixture. Hence a dry process that is relative free of organics can provide significant advantages, particularly in the context of a nickel-zinc cell employing an electrolyte having a relatively low hydroxide concentration.
  • the positive electrode composition for a dry process includes nickel hydroxide, zinc oxide, cobalt oxide (CoO), nickel metal, and optionally cobalt metal, with the zinc and cobalt oxides present, at least partially, in chemical mixture with the nickel hydroxide. Additionally a finely divided binder such as dry P.T.F.E. may be employed. This material provides the adhesion necessary for electrode structural integrity in the absence of CMC and an aqueous media.
  • the dry blended materials are tnetered into compression rollers together with the three-dimensional carrier. As the powders fill the void space they are compressed to the appropriate porosity.
  • the composition of positive electrode employed in the dry mixing procedure is very similar to that employed in wet processes described above.
  • the CMC binder is not used, and obviously much less water is employed as no paste or slurry is produced.
  • the dry positive electrode components are electrochemically active nickel (nickel hydroxide (Ni(OH) 2 ), nickel oxide and/or nickel oxyhydroxide), zinc oxide, cobalt oxide, and cobalt metal. Note that no binder is included here, as it will be introduced later in this embodiment.
  • Mixing of the components may be accomplished using a mixing apparatus suitable for mixing powders or granular compositions.
  • a mixer apparatus may employ blades, impact wheels, rollers, ribbons, internal screws, vibrating elements, and the like to effect even mixing.
  • mixing is accomplished manually using, e.g., a spatula.
  • a binder such as PTFE (polytetrafluoroethylene) may be added to a level of between about 0.1 and 5 percent by weight of the total dry mixture of positive electrode components.
  • Other binder materials may be used in place of or in conjunction with PTFE. As binders, these materials "bind" the other components of the electrode to thereby hold them in place and minimize the likelihood of flaking or otherwise separating from the current collector.
  • chosen binder materials are inert to the electrochemical environment of the positive electrode. That is, the binder materials do not decompose, melt, or diffuse out of the positive electrode during fabrication or during normal operation, hi certain embodiments, such materials resist oxidation or other chemical degradation. Preferably, they will not generate carbon dioxide or carbonates.
  • One example of a class of materials having members that can serve as useful electrode binders in accordance with embodiments of this invention is the fluorinated polyolefins.
  • the binder may be added in a dry state or as an emulsion, for example, hi a specific embodiment, when the binder is a fluorinated polyolefin, it is provided as an emulsion comprising approximately 60 percent by weight binder. It is combined with the remainder of the components manually or by any suitable mixing apparatus (such as those identified above) to produce an evenly dispersed mixture that is subsequently heated to remove the moisture, hi a manual process, the person responsible for mixing may use a spatula or similar tool to effect the mixing. In some embodiments, the binder and remaining components of the positive electrode are combined in a single step, as opposed to the two-stage procedure described above.
  • a foam or expanded metal current collector is employed for this purpose - e.g., a nickel foam having a density of between about 300 and 600 gm/m 2 , and more preferably between about 450 and 500 gm/m 2 .
  • the positive electrode mixture may be applied to the substrate by, for example, brushing, pressing, or the like, in a continuous fashion. In alternative embodiments, application is accomplished in a batch fashion, or in a semi-continuous fashion, whereby the mixture is applied to a "plaque" of substrate sufficient to form, for example, 8-10 cells.
  • the plaque, with applied positive electrode material is cut, scored, and otherwise processed to generate individual strips of electrode for assembly in the final cell.
  • Brushing may be accomplished by manually brushing in the electrode mixture with a brush and periodically checking to ensure the correct amount of positive electrode material has been incorporated in the current collector foam or other substrate material. To this end, the substrate and incorporated electrode material may be weighed from time-to-time until a set endpoint is reached.
  • Brushing may also be automated using, for example, an apparatus having two or more brushes positioned on opposite sides of the substrate where they receive a supply of electrode material. As the substrate passes between the brushes, electrode material is drawn into substrate. [0061] Thereafter, in accordance with an embodiment of this invention, the electrode material is compressed onto the substrate by an appropriate technique such as calendaring. In a specific embodiment, the electrode and carrier are passed vertically through calendaring rollers to produce a compressed electrode sheet of appropriate dimensions. In a specific embodiment, the resulting electrode has a thickness of between about 10 and 50 mils, or between about 20 and 30 mils. [0062] After the material has been applied, an external coating may be applied.
  • the coating serves to encapsulate the electrode material or at least reduce the likelihood that the material will separate from the carrier.
  • the coating comprises PTFE or physically similar material.
  • the electrode is dipped in or sprayed with an emulsion of the coating material (e.g., an emulsion of about 60 weight percent PTFE).
  • the resulting electrode and carrier assembly (whether coated or not) is subjected to "microcracking.” This is a process of bending the electrode sheet while under tension to introduce "microcracks" and thereby make the electrode more flexible.
  • One apparatus for introducing microcracks employs offset rollers through the electrode sheet is pulled under tension.
  • the carrier/electrode sheet must be periodically cut.
  • the carrier is sized to support positive electrodes for one or a pre-set number of cells, hi the case where the carrier supports electrodes for a set number of cells (e.g., 8 cells), it is referred to as a plaque.
  • the plaque is cut into multiple individual electrode strips, hi a specific embodiment, at least one such cut is made lengthwise along the plaque so that the cut defines a top portion one electrode strip and a bottom portion of another electrode strip, with the top and bottom designations referring to positions within an assembled cell.
  • the carrier sheet is coated with positive electrode material
  • the resulting sheet is dried (127), if necessary, to drive off excess water and then compressed (129).
  • These process operations can be performed in much the same manner as operations 107 and 109 for the negative electrode.
  • compression brings the electrode to a uniform desired thickness and porosity as described above for the negative electrode path.
  • the resulting positive electrode sheet has a thickness of between about 15 and 40 mils (e.g., about 25 mils) and has a porosity of between about 30 and 45%.
  • a similar process to that outlined above for the positive electrode may be applied to the negative electrode.
  • a positive electrode After a positive electrode is prepared as described above, it may be tabbed and slit as indicated at a step 131.
  • the slitting of the electrodes to width may be done before or after tabbing, however most automated lines slit the electrode stock after an in-line tabbing process. Tabbing of the coined edges facilitates the final welding of the current collector arrangement after winding of the jelly-roll.
  • the current collector (substrate) may be a nickel foam or other material having a large void fraction.
  • the process may include applying the metal tab (e.g., a thin nickel sheet of about 0.08 to .15 inches width) along one lengthwise edge of the current collector.
  • the tab After rolling the tabbed positive electrode into a jellyroll, the tab makes contact with the collector disk by, e.g., soldering, welding, or pressure contact.
  • the tab may be affixed to the edge of the current collector (where the wet or dry electrode mixture has not been applied) at various stages in the above process by, e.g., a seam welding process, a resistance welding process, or an ultrasonic welding process.
  • no tab is employed, even when using a high void volume current collector such as a nickel foam, hi such a case the coined non- pasted area may be folded over to create a planar or generally planar surface that is more readily bonded to a current collector disc.
  • the coined area may be cut to allow ease of bending. For example, sections may be cut away to leave multiple small tabbed sections. After bending, contact to the current collector plate or disc may be made either by resistance welding or by pressure contact, hi these embodiments, the positive electrode jellyroll foam directly contacts the collector disk and no intermediate features such as a tab are employed. Application of this design in "reverse polarity" or negative cap design is described elsewhere herein.
  • the two paths (negative electrode fabrication and positive electrode fabrication) converge to provide a layered arrangement of sheets that remain with the cell to completion.
  • multiple sheets of material are brought together and wound or otherwise assembled into a cell structure.
  • four sheets of separator material (depicted as sources 113 and 133) are interleaved with the positive electrode sheet and the negative electrode sheet.
  • the separator for the positive electrode is sandwiched between semi-permeable separator sheets (113, 133).
  • the separator for the negative electrode (133) comprises a nylon sheet.
  • Other separator materials known in the art may be employed.
  • nylon-based materials and microporous polyolefins e.g., polyethylenes and polypropylenes are suitable.
  • FIG. 3 is a cross-sectional representation of the positive and negative electrodes prior to winding.
  • separators (301, 305) are initially folded over the electrodes (303, 307) along the electrode's planar surface before being drawn or fed, with the electrode sheets, into a winding apparatus 309.
  • two sources of separator are employed.
  • each electrode sheet is straddled by two separate sources of separator sheet so that four sources of separator, rather than two are employed.
  • a separator sheet is not folded over the leading edge of an electrode.
  • the resulting layered structure is the same.
  • Both approaches produce a structure in which two layers of separator separate each electrode layer from the next adjacent electrode layer. This is generally not the case with nickel cadmium cells, which employ only a single layer of separator between adjacent electrode layers.
  • the additional layers employed in the nickel zinc cell help to prevent shorting that could result from zinc dendrite formation.
  • Dendrites are crystalline structures having a skeletal or tree-like growth pattern ("dendritic growth") in metal deposition. In practice, dendrites form in the conductive media of a power cell during the lifetime of the cell and effectively bridge the negative and positive electrodes causing shorts and subsequent loss of battery function.
  • the separator sheets generally do not entirely cover the full widths of the electrode sheets. Specifically, one edge of each electrode sheet remains exposed for attaching terminals at step 203. This is the edge that was wiped clean of electrode material at steps 111 and 131. Further, and for the same reason, the electrodes are offset laterally by approximately the width of the cleaned strip that was discussed above. This presents one lateral edge having only exposed negative current collector and the opposite lateral edge having only exposed positive current collector to accommodate terminal attachment in step 203.
  • the winding apparatus draws the various sheets in at the same time and rolls them into a jellyroll-like structure. After a cylinder of sufficient thickness is produced, the apparatus cuts the layers of separator and electrodes to produce the finished cell assembly.
  • FIG. 2 a continuation of the process flow of FIG. 1 is shown.
  • the process of FIG. 2 begins with a cell assembly 201 resulting from the assembling operation "A."
  • this assembly is a jellyroll-like structure, hi an alternative embodiment, it is a rectangular or prismatic layered structure.
  • the form factor of the cell assembly is user dependent and may take any of a number of forms well known in the art. If a prismatic form is used, it may be desirable to pre-wrap the positive and negative electrode sheets in their own separators prior to assembly.
  • a positive terminal is conductively attached to the exposed positive current collector at one axial end of the cell assembly and a negative terminal is conductively attached to the exposed negative current collector at the other axial end of the cell assembly.
  • Attachment of the internal terminal may be accomplished by any method well known in the art such as spot welding, ultrasonic welding, laser welding, soldering, pressure contacting, or any other type of electro-conductive bonding appropriate for the terminal and current collector materials. Specific approaches for attaching a copper internal terminal are described below.
  • the internal terminals comprise disks, which may or may not be perforated or slotted. Bi another embodiment, the internal terminals comprise H-shaped structures. Regardless of their actual structure, the internal terminals may be conductively attached to the electrodes without requiring tabs to be present on the electrode with which an internal terminal may attach.
  • the cell assembly is inserted into a retaining vessel (205) such as a can in the case of a cylindrical cell assembly.
  • the can or other vessel serves as the outer housing or casing of the final cell.
  • the terminal disks (or other internal terminals) can be conductively attached to the cell's can and lid or other external terminals at step 207.
  • the external terminals provide direct electrical access to the power cell for a powered device.
  • the external terminals in some embodiments, are preferably plated with a non-corrosive metal such as nickel plate. Further, the external terminals may function to isolate the electrodes from mechanical shock. Given the portable nature of electronic devices, the likelihood of mechanical shock is reasonably high. If the external terminals were directly attached with the electrode current collectors, significant failure of the welded joint or direct damage to the electrodes might occur.
  • an appropriate electrolyte is provided.
  • the electrolyte should possess a composition that limits dendrite formation and other forms of material redistribution in the zinc electrode.
  • Such electrolytes have generally eluded the art. But one that appears to meet the criterion is described in U.S. Patent No. 5,215,836 issued to M. Eisenberg on June 1, 1993, which is hereby incorporated by reference.
  • a particularly preferred electrolyte includes (1) an alkali or earth alkali hydroxide present in an amount to produce a stoichiometric, excess of hydroxide to acid in the range of 2.5 to 11.0 equivalents per liter, (2) a soluble alkali or earth alkali fluoride in an amount corresponding to a concentration range of 0.01 to 1.0 equivalents per liter of total solution, and (3) a borate, arsenate, and/or phosphate salt (preferably potassium borate, potassium metaborate, sodium borate, and/or sodium metaborate).
  • the electrolyte comprises 4.5 to 10 equiv/liter of potassium hydroxide, from 2.0 to 6.0 equiv/liter boric acid or sodium metaborate and from 0.01 to 1.00 equivalents of potassium fluoride.
  • a currently preferred electrolyte for high rate applications comprises 8 equiv/liter of hydroxide, 4.5 equivalents of boric acid and 0.2 equivalents of potassium fluoride.
  • the invention is not limited to the electrolyte compositions presented in the Eisenberg patent. Generally, any electrolyte composition meeting the criteria specified for the applications of interest will suffice. Assuming that high power applications are desired, then the electrolyte should have very good conductivity. Assuming that long cycle life is desired, then the electrolyte should resist dendrite formation, hi the present invention, the use of borate and/or fluoride containing KOH electrolyte along with appropriate separator layers reduces the formation of dendrites thus achieving a more robust and long-lived power cell.
  • the electrolyte composition includes an excess of between about 3 and 5 equiv/liter hydroxide (e.g., KOH), NaOH, LiOH.
  • KOH equiv/liter hydroxide
  • NaOH equiv/liter hydroxide
  • LiOH equiv/liter hydroxide
  • the negative electrode is a zinc oxide based electrode.
  • alternate electrolyte formulations may be appropriate.
  • an appropriate electrolyte for calcium zincate has the following composition: about 15 to 25% by weight KOH, about 0.5 to 5.0% by weight LiOH.
  • Various techniques may be employed to fill the vessel with electrolyte. hi one example, the electrolyte is introduced via an injection process in which electrolyte enters the cell via a fill port.
  • the electrolyte may be added prior to lid application and the cell is spun to distribute the fluid.
  • the vessel is sealed to isolate the electrodes and electrolyte from the environment. See block 211.
  • any of a number of sealing methods may be utilized including, but not limited to crimping, welding, stamping, or gluing. Note that in a cylindrical cell, the lid is typically seated on a gasket residing on a circumferential bead in the upper portion of the can. To effect sealing, the top edge of the can is then crimped down toward the lid without making electrical contact.
  • the cell is generally sealed from the environment, the cell may be, in some embodiments, permitted to vent gases from the battery that are generated during charge and discharge.
  • a typical nickel cadmium cell vents gas at approximately 200 PSI.
  • a nickel zinc cell is designed to operate at this pressure and even higher (e.g., up to 300 PSl) without the need to vent. This may encourage recombination of any oxygen and hydrogen generated within the cell.
  • the cell is constructed to maintain an internal pressure of not greater than about 600 PSI and more preferably not greater than about 450 PSI.
  • a nickel zinc cell is designed to vent gas at relatively lower pressures.
  • a vent mechanism is preferably designed to allow gas escape but not allow electrolyte passage that may interfere with the reproducible function of the vent.
  • the use of hydrophobic membranes can be effective for this purpose (see e.g., US Patent Application No. 10/098,193, "Leak Proof Pressure Relief Valve for Secondary Batteries," filed March 15, 2002 for J. Phillips, which is incorporated herein by reference for all purposes) and these may be used alone or in conjunction with a tortuous gas escape route.
  • Many other battery venting mechanisms are known in the art and are suitable for use with this invention.
  • Formation of the cell is accomplished at step 213.
  • a formation cycle follows a specific voltage-current-time curve that accounts for factors such as electrode composition and cell capacity.
  • formation is accomplished using a large power supply that charges numerous cells at once over a period of, for example, about 24 to 74 hours.
  • formation and related operations may be performed as follows. The cells are vacuum filled with electrolyte and soaked for less than 2 hours (for comparison, nickel cadmium cells are generally soaked for 24 hours but are usually drip filled).
  • the formation protocol includes a discharge and recharge step that is believed to help distribute electrolyte, but this example can be practiced without this operation. In another example, the mid-formation discharge is eliminated.
  • Cells may be charged singly or with two in series, but in a production environment it is more usual to charge the cells in larger series strings.
  • one may monitor the voltage behavior over the complete formation process and collect weight loss, impedance values and open circuit voltages to classify and identify possible weak cells.
  • each cell is discharged during a quality control step 215 to determine the particular capacity of each cell.
  • Cells having similar capacities are grouped for use in the same battery packs. In this way, each cell in a battery pack becomes fully charged after receiving substantially the same quantity of charge. Thus, when charge is complete no cell in the pack is significantly under utilized and no cell in the pack is significantly overcharged. Groupings of batteries may be restricted to two or more groupings depending on the nature and sensitivity of the application.
  • the operations of FIG. 2 are generally the same as or very similar to corresponding operations employed in the manufacture of nickel cadmium cells. Hence, the apparatus employed for these operations in nickel cadmium cell fabrication generally can also be used in nickel zinc cell fabrication.
  • the electrode, current collector, and electrolyte differences may require customized apparatus or processing.
  • the zinc electrode may employ a copper current collector, which cannot be employed with a cadmium electrode. While copper has better electronic conductivity than steel, it can present fabrication issues. For example, attaching a current collecting copper disk to the copper sheet may require specific laser welding settings and the appropriate jigs to provide continuous pressure during the weld.
  • Nickel zinc cells prepared in accordance with this invention may have particularly useful properties for power tool and UPS applications. For example, energy densities will exceed about 60Wh/kg and continuous power densities are commonly in excess of about 500W/kg or even 1000W/kg.
  • the polarity of the cell's terminals is reversed in comparison to conventional cells for consumer electronics. Many of the same methods of manufacture described herein are utilized to accomplish this embodiment with minor variations that are herein described.
  • the polarity of the cell is established wherein the lid is positive and the can or vessel is negative. That is, the positive electrode of the cell assembly is electrically connected with the lid and the negative electrode of the cell assembly is electrically connected with the can that retains the cell assembly.
  • the lid is electrically isolated from the can through the use of a flexible gasket and a bituminous sealing agent.
  • FIG. 4a is a graphical representation of a reverse polarity power cell sub assembly embodiment.
  • a cell assembly (407) is manufactured using the techniques provided herein.
  • a negative internal terminal (405) is electrically connected with the negative electrode of the cell assembly. Because of the unique properties of Nickel/Zinc electrochemistry, the negative internal terminal (405) is preferably comprised of copper.
  • conventional power cells exhibit an overall impedance of approximately 3 to 5 milliohms. Approximately 0.8 milli- Ohm may be attributed to the positive current collector and the resistance weld to the cap. This is due in part to the compositional requirements of the terminal given the electrochemistry of conventional power cells.
  • the use of copper in the manner described results in a significant impedance reduction of approximately 0.5 milli-Ohm at the now negative terminal thus achieving a more power efficient cell.
  • slightly higher impedance cells may be constructed by coating or plating the interior surface of the retaining vessel (411) with copper, and subsequently making contact to the negative current collection disc, although this method would necessitate alternative manufacturing steps.
  • copper in this and other embodiments, requires particular attention when used as an internal terminal.
  • copper as is well known in the art, is particularly effective, not only in carrying current, but also in conducting heat.
  • the electrical attachment of the internal terminal with the negative electrode requires specific manufacturing techniques, hi an example embodiment, the copper internal terminal is perforated and attached at multiple points along the negative electrode so that the electrode is attached to the current collector at multiple points along its length. By activating a greater area, the charge and discharge efficiency is further enhanced. The perforations also serve to locate the electrode and allow electrolyte to penetrate the stack uniformly during the electrolyte fill operation. hi another embodiment, the internal terminal is slotted to achieve the named advantages.
  • copper is particularly efficient in conducting heat requiring novel techniques of attaching the internal terminal with the negative electrode to avoid damaging the negative electrode.
  • these novel techniques may be used in conjunction with other techniques well known in the art such as spot welding, ultrasonic welding, laser welding, non-welding heat bonding (e.g., soldering), compression bonding, or any other type of electro-conductive bonding appropriate for the terminal and current collector materials.
  • laser welding is employed to form a low impedance connection between the internal terminal and the copper current collector. In a specific approach, the laser welding is performed in cross fashion or other tracking method that maximizes the number of weldments, in which the laser is moved across the surface of the internal terminal to catch each point.
  • Another embodiment employs soldering to bond a copper internal terminal to copper sheet of the jelly-roll.
  • the internal terminal and the jelly-roll are brought into contact at a temperature that causes soldering.
  • a thin layer of a solderable metal is applied to the internal terminal. It may be applied over one or both faces of the terminal coating the entire face(s) or just specific regions thereof.
  • the metal may be applied by electroplating, electroless plating, high temperature contact with the metal, etc.
  • the chosen metal should be electrochemically compatible with the zinc electrode and resist corrosion when contacting electrolyte at potentials typically encountered during overcharge and over- discharge.
  • the internal terminal is coated on at least one face with tin or a tin alloy having a thickness of between about 0.0002 and 0.002 inches.
  • the contact is made by compression between the internal terminal and the copper of the jelly-roll. Such compression may be provided by downward force provided by the cell cap in the fully assembled cell.
  • some embodiments employ a 0-ring or other elastomeric member or a metallic spring device interposed between the cap and the internal terminal.
  • the internal terminal is provided as a folded unitary member having one wing contacting the jelly-roll and another wing contacting the cell cap.
  • An O-ring or other elastomeric member or copper plated stainless steel spring is located between the two wings of the internal terminal so that when the cell cap is positioned it transfers downward force from one wing of the terminal to the O-ring and onto the second wing of the terminal, which abuts the jelly- roll.
  • FIG. 4b is presented to further clarify the embodiment described above, hi particular, FIG. 4b is a graphical cross-sectional representation of a reverse polarity power cell sub assembly embodiment.
  • FIG. 4b illustrates the position of the insulating gasket (403) that serves to electrically isolate the negative external terminal (i.e. the lid (401)) from the positive external terminal (i.e. the can (409). It is contemplated that a variety of materials may be used to achieve electrical isolation in the present embodiment.

Abstract

La présente invention concerne des procédés de fabrication d'une pile rechargeable. Les procédés consistent à utiliser une suspension, une pâte ou un mélange sec de matériaux d'électrode négative à faible toxicité et comportant des dispersants qui empêchent l'agglomération de particules capable d'endommager l'efficacité des piles. Dans les procédés, on utilise des feuilles semi-perméables pour séparer les électrodes et réduire au maximum la formation de dendrites, puis on utilise un électrolyte spécifique aux électrodes pour produire une réaction électrochimique efficace et pour gêner la croissance dendritique dans la cellule. Les matériaux d'électrode négative peuvent être le zinc et les composés de zinc, qui sont tous notablement moins toxiques que le cadmium utilisé dans les accumulateurs au nickel-cadmium. Les procédés selon l'invention peuvent comprendre l'utilisation de techniques de production employées dans les chaînes de production NiCad existantes. Les procédés selon l'invention sont ainsi particulièrement utiles dans un cadre de fabrication déjà bien défini et évolué.
EP06736671A 2005-03-01 2006-03-01 Procede de fabrication d'accumulateurs au nickel-zinc Withdrawn EP1859504A2 (fr)

Applications Claiming Priority (2)

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US65782505P 2005-03-01 2005-03-01
PCT/US2006/007390 WO2006094110A2 (fr) 2005-03-01 2006-03-01 Procede de fabrication d'accumulateurs au nickel-zinc

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EP1859504A2 true EP1859504A2 (fr) 2007-11-28

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EP (1) EP1859504A2 (fr)
JP (1) JP2008532249A (fr)
KR (1) KR20070116045A (fr)
CN (2) CN101194390A (fr)
CA (1) CA2599730A1 (fr)
WO (1) WO2006094110A2 (fr)

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7931988B2 (en) * 2007-10-05 2011-04-26 Powergenix Systems, Inc. Tin and tin-zinc plated substrates to improve Ni-Zn cell performance
US8048566B2 (en) * 2008-02-07 2011-11-01 Powergenix Systems, Inc. Nickel hydroxide electrode for rechargeable batteries
US8501351B2 (en) * 2009-05-18 2013-08-06 Powergenix Systems, Inc. Pasted zinc electrode for rechargeable nickel-zinc batteries
CN102484279B (zh) * 2009-09-08 2015-06-17 鲍尔热尼系统公司 镍锌电池的热密封隔膜
DE102010014700A1 (de) * 2010-04-12 2011-10-13 Ke-Tec Gmbh Folienableiter für Flachzellen und Verfahren zu dessen Herstellung
WO2012163300A1 (fr) * 2011-06-03 2012-12-06 苏州宝时得电动工具有限公司 Batterie
CN105375070A (zh) 2011-08-23 2016-03-02 株式会社日本触媒 凝胶电解质以及使用了该凝胶电解质的电池
US9337483B2 (en) 2013-01-14 2016-05-10 Powergenix Systems, Inc. Pasted nickel hydroxide electrode and additives for rechargeable alkaline batteries
JP6397646B2 (ja) * 2014-03-31 2018-09-26 株式会社日本触媒 亜鉛電極用合剤
JP6573682B2 (ja) * 2015-12-24 2019-09-11 日本碍子株式会社 電極積層体及びそれを用いたニッケル亜鉛電池
CN109802092A (zh) * 2019-02-14 2019-05-24 嘉兴市得高电源科技有限公司 一种正极粉挤压浇注入筒工艺
US20230387512A1 (en) * 2020-10-30 2023-11-30 Fundación Cidetec Aqueous batteries with high reversibility
CN113548768A (zh) * 2021-07-02 2021-10-26 北京津工海水科技有限公司 一种dtro排放垃圾渗透积存液深度处理方法

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5461B2 (fr) * 1973-11-21 1979-01-05
US3898099A (en) * 1974-03-18 1975-08-05 Energy Res Corp Hydrophilic electrode and method for making the same
US4130696A (en) * 1976-09-09 1978-12-19 Yardney Electric Corporation Conductive diluent for pressed nickel electrodes
DE2803151A1 (de) * 1978-01-25 1979-07-26 Varta Batterie Verfahren zur herstellung positiver ni(oh) tief 2 -presselektroden
JPS606073B2 (ja) * 1979-11-07 1985-02-15 松下電器産業株式会社 渦巻電極体を備えた電池の製造法
US6436575B1 (en) * 1998-11-13 2002-08-20 Moltech Power Systems, Inc. Pasted positive electrode and process for its production
US7829221B2 (en) * 2000-11-10 2010-11-09 Powergenix Systems, Inc. Cobalt containing positive electrode formulation for a nickel-zinc cell
US6818350B2 (en) * 2001-03-15 2004-11-16 Powergenix Systems, Inc. Alkaline cells having low toxicity rechargeable zinc electrodes
CN1283022C (zh) * 2003-03-10 2006-11-01 华南理工大学 锌镍二次电池及其制备方法
EP1661195B1 (fr) * 2003-08-18 2016-01-13 PowerGenix Systems, Inc. Procede de fabrication de piles nickel-zinc

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2006094110A2 *

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CN101964430B (zh) 2012-09-26
KR20070116045A (ko) 2007-12-06
WO2006094110A3 (fr) 2007-04-05
WO2006094110A2 (fr) 2006-09-08
CN101194390A (zh) 2008-06-04
CA2599730A1 (fr) 2006-09-08
JP2008532249A (ja) 2008-08-14
CN101964430A (zh) 2011-02-02

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