Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/04—Hybrid capacitors
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/22—Electrodes
  • H01G11/26—Electrodes characterised by their structure, e.g. multi-layered, porosity or surface features
  • H01G11/28—Electrodes characterised by their structure, e.g. multi-layered, porosity or surface features arranged or disposed on a current collector; Layers or phases between electrodes and current collectors, e.g. adhesives
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/52—Separators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/84—Processes for the manufacture of hybrid or EDL capacitors, or components thereof
• • 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
  • H01M10/04—Construction or manufacture in general
  • H01M10/0413—Large-sized flat cells or batteries for motive or stationary systems with plate-like electrodes
  • H01M10/0418—Large-sized flat cells or batteries for motive or stationary systems with plate-like electrodes with bipolar 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
• • 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
• • 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
  • H01M4/0402—Methods of deposition of the material
  • H01M4/0409—Methods of deposition of the material by a doctor blade method, slip-casting or roller coating
• • 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
  • H01M4/0416—Methods of deposition of the material involving impregnation with a solution, dispersion, paste or dry powder
• • 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
  • H01M4/0419—Methods of deposition of the material involving spraying
• • 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
  • H01M4/0421—Methods of deposition of the material involving vapour deposition
  • H01M4/0428—Chemical vapour deposition
• • 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
  • H01M4/045—Electrochemical coating; Electrochemical impregnation
• • 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
  • 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
  • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
• • 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
  • H01M50/183—Sealing members
  • H01M50/184—Sealing members characterised by their shape or structure
• • 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
  • H01M50/183—Sealing members
  • H01M50/186—Sealing members characterised by the disposition of the sealing members
• • 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
  • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
• • 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
  • H01M50/543—Terminals
  • H01M50/547—Terminals characterised by the disposition of the terminals on the cells
  • H01M50/548—Terminals characterised by the disposition of the terminals on the cells on opposite sides of the cell
• • 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
  • H01M50/543—Terminals
  • H01M50/552—Terminals characterised by their shape
  • H01M50/553—Terminals adapted for prismatic, pouch or rectangular cells
  • H01M50/557—Plate-shaped terminals
• • 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
  • H01M50/60—Arrangements or processes for filling or topping-up with liquids; Arrangements or processes for draining liquids from casings
  • H01M50/609—Arrangements or processes for filling with liquid, e.g. electrolytes
  • H01M50/627—Filling ports
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M6/00—Primary cells; Manufacture thereof
  • H01M6/42—Grouping of primary cells into batteries
  • H01M6/46—Grouping of primary cells into batteries of flat cells
  • H01M6/48—Grouping of primary cells into batteries of flat cells with bipolar 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
  • H01M4/04—Processes of manufacture in general
  • H01M4/0438—Processes of manufacture in general by electrochemical processing
• • 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 generally relates to an energy storage device, and more particularly to a bipolar double layer capacitor-type energy storage device, and to methods for manufacturing the same.
• Enerqv Storage Devices There has been significant research over the years, relating to useful reliable electrical storage devices, such as a capacitor or a battery. Large energy storage capabilities are common for batteries; however, batteries also display low power densities. In contrast, electrolytic capacitors possess very high power densities and a limited energy density. Further, carbon based double-layer capacitors have a large energy density; but, due to their high equivalent series resistance (ESR), carbon electrodes have low power capabilities. It would therefore be highly desirable to have an electrical storage device that has both a high energy density and a high power density.
• ESR equivalent series resistance
• J. Kalenowsky discusses a capacitive power supply having a charge equalization circuit. This circuit allows a multicell capacitor to be charged without overcharging the individual cells. The present invention does not require a charge equalization circuit to fully charge a multicell stack configuration without overcharging an intermediate cell.
• H. Lee, et al. in IEEE Transactions on Magnetics, Vol. 25 (#1 ), p.324 (January 1989), and G. Bullard, et al., in IEEE Transactions on Magnetics. Vol. 25 (#1 ) p. 102 (January 1 989) discuss the pulse power characteristics of high-energy ceramic-oxide based double-layer capacitors. In this reference various performance characteristics are discussed, with no enabling discussion of the construction methodology. The present invention provides a more reliable device with more efficient packaging.
• Carbon electrode based double-layer capacitors have been extensively developed based on the original work of Rightmire, U.S. Patent No. 3,288,641 .
• A. Yoshida et al. in IEEE Transactions on Components, Hybrids and Manufacturing Technology, Vol. CHMT-10, #1 ,P-100 - 103 (March 1987) discusses an electric double-layer capacitor composed of activated carbon fiber electrodes and a nonaqueous electrolyte.
• the packaging of this double-layer capacitor is revealed. This device is on the order of 0.4-1 cc in volume with an energy storage capability of around 1 -10 J/cc.
• Additional references of interest include, for example:
• a common way to maintain separation between electrodes in an electrical storage device with an electrolyte present is by use of an ion permeable electrically insulating porous membrane.
• This membrane is commonly placed between the electrodes and maintains the required space separation between the two electrodes.
• Porous separator material such as paper or glass, is useful for this application and is used in aluminum electrolytic and double layer capacitors. However, for dimensions below 1 or 2 mil (0.00254 to 0.00508 cm) in separation, material handling is difficult and material strength of the capacitor is usually very low.
• the open cross-sectional areas typical of these porous membrane separators are on the order of 50-70%.
• Polymeric ion permeable porous separators have been used in carbon double layer capacitors as discussed by Sanada et al. in IEEE, pp.224-230, 1 982, and by
• a method of using photoresist to fill voids of an electrically insulating layer to prevent electrical contact between two electrode layers for use as a solar cell is disclosed by J. Wilfried in US Patent No. 4,774, 1 93, issued September 27, 1 988.
• the present invention relates to a novel electrical storage device that has both a high energy density and a high power density.
• an energy storage device such as a capacitor, which includes a plurality of cells in a bipolar configuration.
• the cells are stacked and bonded together, to impart to the device an integral and unitary construction.
• Each cell includes two electrically conductive electrodes that are spaced apart by a predetermined distance.
• the cell also includes at least one dielectric gasket that is interposed, in relation to each other, between the electrodes, for separating and electrically insulating these electrodes.
• Each cell also includes a high surface area (porous) electrically conductive coating layer that is formed on one (or, more) surface of each electrode.
• This coating layer optionally includes a set of closely spaced-apart peripheral microprotrusions, and a set of distally spaced-apart central microprotrusions. These microprotrusions are formed by novel screen printing or photolithographic printing methods. These microprotrusions impart structural support to the cells, and provide additional insulation between the electrodes.
• An ionically conductive medium fills the cell gap and pores of the high surface area coating.
• Figure 1 is a perspective view of the preunit 10 a dry energy storage device which is constructed according to the present invention
• Figure 1 A is a perspective view of the electrolyte-filled energy storage device 10A of the present invention
• Figure 2 is a cross-sectional view of the storage device of Figure 1 showing a removable cord 1 17A within the storage device, taken along line 2-2 thereof;
• Figure 2A is another cross-sectional view of the storage device of Figure 1 , taken along line 2A-2A thereof;
• Figure 3 is a schematic representation of an exploded view of the preunit of Figure 1 , illustrating three cells;
• Figure 4 is a block diagram of the manufacture steps of the storage device 10A;
• Figure 5 is a top plan view of a porous coating layer with microprotrusions which forms a part of the storage device of Figures 1 through 4;
• Figure 6 is a diagrammatic illustration of a capacitive circuit, which is equivalent to the device 10A;
• Figure 7 is a schematic representation of a screen printing method to produce microprotrusions on a coating layer used with the energy storage device according to the present invention;
• Figure 8 is a schematic representation of an electrode holder used in the manufacture method of Figure 7;
• Figure 9 is a schematic representation of a method to photolithographically produce the microprotrusions according to the present invention.
• Figure 10 is a schematic isometric view of a pair of hot rollers used for laminating a photoresist to an electrode prior to photolithography;
• Figure 1 1 is a schematic isometric view of a mask placed over the photo resist of Figure 10;
• Figure 1 2 is a schematic isometric view illustrating the exposure of unprotected portions of the photo resist of Figures 10 and 1 1 ;
• Figure 1 3 is a cross-sectional view of an electrode which forms a part of the energy storage device, taken along line 1 3-1 3 of Figure 3; and Figure 14 is a schematic cross-sectional view of two bipolar electrodes with the high surface area porous coating layer on the electrically conducting substrate forming one cell.
• Figure 1 5 is a schematic view of a frame used to hold thin support materials during the dip coating process
• Figure 1 5 A is a schematic view of wire used in the frame of Figure 1 5.
• Cord refers to the thin strips of material included in the method of manufacture of the dry preunit. After initial heating, the removal of the cord produces the open fill ports.
• Electrode support material refers to any electrically conducting metal or metal alloy, electrically conducting polymer, electrically conducting ceramic, electrically conducting glass, or combinations thereof. Metals and metal alloys are preferred for producing stock units.
• the support material should have a conductivity of greater than about 1 0 ⁇ 4 S/cm.
• “Second electrically conducting material” (having a high surface area) refers to a porous electrode coating which may be of the same or different composition on each side of the support material.
• Preferred metal oxides of the present invention include those independently selected from tin, lead, vanadium, titanium, ruthenium, tantalum, rhodium, osmium, iridium, iron, cobalt, nickel, copper, molybdenum, niobium, chromium, manganese, lanthanum, or lanthanum series metals or alloys or combinations thereof, and possibly containing additives like calcium to increase electrical conductivity.
• Electrode refers to an ionically conductive aqueous or non-aqueous solution or material, which enables the dry preunit to be electrically charged.
• Cab-0-Sil ® refers to silica filler available from Cabot Corporation of Tuscola, Illinois. A variety of sizes are available.
• Epoxy refers to the conventional definition of the product which is an epoxy resin mixed with a specific curing agent, usually a polyamine. or polyepoxide mixed with a polyamine curing agent.
• MYLAR ® refers to a polyester of polyethylene terephthalate of DuPont, Inc. of Wilmington, Delaware. It is usually commercially available in sheet form of varying thicknesses.
• Metal oxide refers to any electrically conducting metal oxide.
• Mated metal oxide refers to an electrically conducting oxide compound of two or more metal oxides.
• Photoresist is any photo curable material. Usually, it is an epoxide or acrylate or combinations thereof.
• ConforMASK is a negative working photopolymer available commercially from Dynachem of Tustin, California. This polymer should be used at 50% or less relative humidity. Dry Preunit Energy Storage Device
• FIG. 1 a dry preunit of energy storage device 10 which is constructed according to the present invention.
• the energy storage device is first an assembled dry preunit 10. After filling the present ceils with an electrolyte, the surface is heated to close and to fuse the exterior surface, to form device 10A which is then electrically charged.
• the device preunit 10 generally includes a plurality of cells, such as the cells 1 1 0, 1 1 2 and 1 14, which are formed, prepared, and stacked according to the teaching of the present invention.
• Figure 1 A illustrates an assembled view of the electrical storage device preunit 10A, formed of twelve superposed cells. It should however be understood to those skilled in the art, after reviewing the present specification that any different number of cells can be used.
• Figure 3 is an exploded view of the preunit 1 0, showing only three exemplary cells 1 1 0, 1 1 2 and 1 14.
• the cells have generally similar design and construction, and therefore, only the cells 1 14 and 1 1 2 will be described in detail, in relation to Figures 2, 2A, 3 and 1 3.
• the cell 1 14 includes a first electrically conductive external electrode or end plate 1 1 1 A, and a second internal, electrically conductive bipolar electrode 1 1 1 B. Both electrodes 1 1 1 A and 1 1 1 B are spaced apart at the edges by means of two dielectric or electrically insulating gaskets 1 21 and 1 23.
• a central air filled gap 1 30 ( Figure 2A) is formed by these elements.
• the gap 1 30 is filled with an electrolyte (not shown) to produce device 1 0A.
• an exemplary access or fill port 1 22, is shown in Figure 2A for illustration purpose only, and is formed between the gaskets 1 21 and 1 23, in order to allow the electrolyte to fill the gap 1 30.
• the fill port 1 22 is formed by means of a tab or cord 1 1 7A, which is inserted between the gaskets 1 21 and 1 23, prior to fusing or bonding the gaskets 1 21 and 1 23.
• the cord 1 1 7A becomes surrounded by the reflow gasket material, which causes the outline of fill port 1 22 to be formed.
• the two gaskets become a fused polymer mass covering a minimum of the active electrically conducing coating layers 1 1 9 and 1 20.
• the electrodes 1 1 1 1 A and 1 1 1 1 B in greater detail, the methods of manufacturing them will be described later.
• One difference between the electrodes 1 1 1 A and 1 1 1 B is that the electrode 1 1 1 A optionally includes a tab 1 60A, for connection to a power source (not shown).
• the electrode 1 1 1 A includes one porous electrically conductive coating layer 1 1 9, which is deposited on a support material or structure 1 1 6, while the bipolar electrode 1 1 1 B includes two porous coating layers 1 20 and 1 31 , which are deposited on either or both sides of the support material or structure 1 1 1 B.
• the electrode 1 1 1 B is a true bipolar electrode. It should be understood that both sides of the electrode 1 1 1 A could be coated with porous electrically conductive layers.
• Yet another optional distinction between the electrodes 1 1 1 A and 1 1 1 B lies in the rigidity of the support structures 1 1 1 A and 1 1 1 B.
• the electrode 1 1 1 A acting as an external end plate, should preferably have a more rigid construction, so that it imparts sufficient rigidity to the overall structure of the energy storage device 10A.
• the electrode 1 1 1 B and other similar internal electrodes do not necessarily need to be as rigid as the external electrode 1 1 1 A. Nonetheless, when the device 10A is large, additional support structure is required, and the internal electrodes, i.e. 1 1 1 B, are used as additional support structure. In this case, it is desirable to rigidity the internal electrodes, i.e. 1 1 1 B. As a result, the support material 1 1 6 is thicker than the support material 1 1 8.
• the support material 1 1 6 has a thickness of about 10 mils (0.0254 cm), while the support material 1 1 8 has a thickness of about 1 mil (0.00254 cm). Other values could alternatively be selected.
• the electrodes 1 1 1 A, 1 1 1 B and the remaining electrodes of the storage device 10A are sized and dimensioned according to the desired application, without departing from the scope of the invention.
• the device 1 0A is miniaturized, e.g. for a cardiac defibrillator.
• the overall volume of the device is one cubic meter or even greater, e.g. for an electric vehicle.
• the dimensions of the electrodes determine the overall capacitance of the storage device 10A.
• the electrodes i.e. 1 1 1 A and 1 1 1 B, are rectangularly shaped.
• these electrodes and consequently the preunit 10 could assume various other shapes, such as circular, square, etc.
• An important feature of the preunit 10 is the flexibility of its design, which enables it to be used in various applications.
• the coating layer 1 1 9 includes a plurality of microprotrusions, while the coating layer 1 20 does not include such microprotrusions. It should be understood, however, that the coating layer 1 20 could alternatively be designed similarly to the coating layer 1 1 9, without departing from the scope of the invention.
• Figure 5 is a top plan view of the coating layer 1 1 9, which includes an array of microprotrusions, and which is deposited on the inner face or flat side of the support material 1 16.
• the coating layer 1 19 is porous with high surface area, electrically conductive, and relatively thin.
• the array includes two sets of microprotrusions. The first set includes a plurality of peripheral microprotrusions 1 25, and the second set includes a plurality of centrally located microprotrusions 1 27.
• the peripheral and the central protrusions 125 and 1 27 are similarly designed, and are generally semi-spherically shaped. However, other shapes, for example a rectangular shape, are contemplated within the scope of the present invention.
• the diameter of each protrusion 1 25 or 1 27 is about 6 mil (0.01 524 cm). Different applications of the device 10 might require that the microprotrusions 125 and 1 27 be differently designed.
• the center-to-center separation of the peripheral microprotrusions 125 is about 20 mil (0.0508 cm), while the center-to-center separation of the central microprotrusions 127 is about 40 mil (0.1016 cm).
• the gasket 1 21 is allowed to cover at least part of the microprotrusions 125, but preferably not the microprotrusions 127.
• the peripheral microprotrusions 125 are adjacently disposed along an outer periphery of the coating layer 1 19. While only four rows of microprotrusions are illustrated, it should be understood to those skilled in the art, that additional rows may added, depending on the size and application of the device 10.
• the central microprotrusions 1 27 are similarly adjacently disposed, in an arrayed arrangement, within a central section 132 of the coating layer 1 1 9. As illustrated in Figure 5, the central microprotrusions 127 are surrounded by the peripheral microprotrusions 1 25.
• the microprotrusions 1 25 and 1 27 are formed on the coating layer 1 1 9 to provide added structural support to the first and second electrodes 1 1 1 A and 1 1 1 B. For instance, if, the second electrode 1 1 1 B starts to sag or bow toward the first electrode 1 1 1 A, the microprotrusions 1 27 will prevent contact between these electrodes 1 1 1 A and 1 1 1 B.
• Figure 5 further shows that the coating layer 1 1 9 further includes a plurality of spacings, i.e. 1 33A through 1 33G, where the cord, i.e., 1 1 7A, are placed, in order to ultimately form the fill port, i.e. 1 22.
• the coved only extends partway into the central section 132.
• the width of the cord is smaller than, or equal to the center-to-center separation between the central microprotrusions 1 27.
• the cord is larger than the center-to-center separation between the peripheral microprotrusions 1 25, to prevent the peripheral microprotrusions from pinching the cord, and preventing it from being removed the spacings are increased in the peripheral microprotrusions.
• the cord may be similar in width to the peripheral microprotrusions separation and no accommodation in the microprotrusion pattern needs to be done.
• the coating layer 1 20 serves a similar function as the coating layer 1 1 9, and is deposited on the side of the electrode 1 1 1 B, which faces the inner side of the first electrode 1 1 1 A.
• the coating layer 1 20 does not include microprotrusions.
• the coating layers 1 1 9 and 1 20 are similarly constructed, and include microprotrusion layers.
• the gaskets 1 21 and 1 23 are generally identical, and are arranged in registration (adjacent and superposable) with each other. For brevity, only the gasket 1 21 will be described in greater detail.
• the gasket 1 21 includes a solid peripheral section 143 and a hollow central section 144.
• the cord 1 1 7A is placed between the gaskets 1 21 and 1 23, and extends across the hollow section, i.e. 144, of the gaskets, and protrudes outside the peripheral section, i.e. 143.
• the cord does not extend across the entire width of the gaskets, and only a part of the cord is sandwiched between the gaskets and extends beyond both edges of one side of the gasket.
• the cell 1 1 2 is generally similar in design and construction to the cell 1 14.
• the cell 1 1 2 includes the bipolar electrode 1 1 1 B, as its first electrode, and a second bipolar electrode 1 1 1 C.
• the electrodes 1 1 1 B and 1 1 1 C are generally identical, and are spaced-apart, in registration with each other.
• a porous coating layer 1 31 which is identical to the coating layer 1 1 9, is deposited on the surface of the support material 1 1 8, facing the electrode 1 1 1 C.
• a coating layer 1 33 which is similar to the coating layer 1 20, is deposited on a support material or structure 140, which forms a part of the electrode 1 1 1 C.
• the cell 1 1 2 further includes two gaskets 135 and 137 that are identical to each other and to the gaskets 1 21 and 1 23 of the cell 1 14.
• a cord 1 1 7B forms a fill port 142 between the gaskets 1 35 and 1 37.
• the cell 1 1 0 is substantially similar to the cell 1 14, and includes a first bipolar electrode 1 1 1 Y, a second electrode 1 1 1 Z, two gaskets 1 57 and 1 59, a cord 1 1 7C, a tab 1 60, and a fill port 1 62. It should be noted that Figure 3 does not show the inner electrode 1 1 1 Y.
• FIG. 6 there is illustrated a diagrammatic view of a capacitive circuit 200 which is representative of, and generally has an equivalent function to the device 10A.
• the circuit 200 illustrates the cell 1 14 as two capacitors C1 and C2; the cell 1 1 2 as two capacitors C3 and C4; and the cell 1 10 as two capacitors C5 and C6.
• the device 10 is generally equivalent to a plurality of capacitors connected in series.
• the porous electrically conducting coating 1 1 9 in conjunction with an ionically conducting medium (not shown) within the cell 1 14, form the capacitor C1 .
• the ionically conducting medium and the coating 1 20 form the capacitor C2.
• the coating 1 31 and the ionically conducting medium within the cell 1 1 2 form the capacitor C3.
• the ionically conducting medium within the cell 1 1 2 and the coating 1 33 form the capacitor C4.
• the cell 1 10 is represented by the capacitors
• An important aspect of the present invention is the bipolar configuration of the energy storage device.
• Figure 14 is a schematic cross-sectional representation of the magnified edge of the magnified edge of the support 1 1 8 & 148A and electrically conducting coating layers (1 20, 1 31 , 1 33, 1 33B).
• the center support 1 88 is depicted as a metal but can be any material which is electrically conducting and provides the support for the coating.
• the coating which has high surface area provides the structure and geometry for the energy storage.
• layer 1 20, etc. has a discontinuous surface with many fissures, micropore and mesopore which create the high surface area.
• the porous coatings 1 20 and 1 31 are coated onto support 1 1 8 to form bipolar electrode 1 1 1 B and coatings 133 and 133B are coated onto support 148A to form bipolar electrode 1 1 1 C.
• the pull tabs are removed creating the fill ports and the preunit 10 is charged with electrolyte 1 90, the fill ports, e,g. 1 17D, are sealed creating device 10A.
• the device 10A is then charged electrically producing the following results at the same time:
• Coating 1 20 becomes negatively charged. Electrically conducting support 1 1 8 conducts electrons accordingly. Thus, porous coating 1 31 becomes positively charged. The ionically conducting electrolyte ions accordingly. An electric double layer is formed at the electrode-electrolyte interface forming the individual capacities in circuit 200. Thus, the surface of coating 1 33 becomes negatively charged, and the surface of coating 1 33B becomes positively charged. Because the porous high surface area oxide allows the effective surface area of the electrode to become very high, the corresponding electrical storage capacity of the device increases dramatically.
• the support material are optionally etched or cleaned by a variety of conventional pickling and cleaning procedures. In some experiments, if the metal surface is not etched it is too smooth. This smooth surface sometimes causes inadequate adhesion of the porous coating. The etch creates a suitable rough surface.
• aqueous inorganic strong acid e.g. sulfuric acid, hydrochloric acid, hydrofluoric acid, nitric acid, perchloric acid or combinations thereof.
• the etching is usually performed at elevated temperatures of 50 to 95 ° C (preferably 75 ° C) for about 0.1 to 5 hr (preferably 0.5 hr) followed by a water rinse. Room temperature acid etching is possible.
• An alkaline etch or an oxalic acid etch may also used.
• the roughened support surface is obtained by sputtering, plasma treatment, and/or ion milling.
• a preferred procedure is Ar RF sputter etching at between around 0.001 and 1 torr with about 1 KeV energy at 13.5 Mhz. Commonly, 0.1 -10 watts/cm 2 power densities for about 1 -60 min. are used to clean and roughen the surface.
• Another procedure is to plasma etch the support with a reactive gas such as oxygen, tetrafluoromethane, and/or sulfurhexafluoride at around 0.1 -30 torr for about 1 -60 min.
• the coating e.g. oxide
• the coating is porous and composed of mostly micropores (diameter ⁇ 1 7A). Large 0.1 -1 ⁇ m wide cracks are present on the surface protruding to depths as thick as the coating. However, greater than 99% of the surface area arises from these micropores. The average diameter of these micropores are around 6-1 2 A.
• the pore structure can be altered to increase the average pore size.
• the steam post-treatment creates a bimodal pore distribution.
• a narrow distribution of mesopores (diameter ⁇ 1 7-1 OOOA) having a diameter of about 35 A is created.
• These treated electrode coatings have 85-95% of the surface area arising from the micropore structure.
• the effective high surface area of the coating is 1 ,000 to 10,000 to
• the electrode 1 1 1 A includes a porous and conductive coating layer 1 1 9, which is formed on at least one surface of the support material 1 1 6.
• the support material 1 1 6 is electrically conductive, and sufficiently rigid to support the coating layer 1 1 9 and to impart sufficient structural rigidity to the device 1 0.
• One goal of the present invention is to optimize the energy density and power density of the device 10.
• the object is achieved by reducing the thickness of the support material 1 1 6, and maximizing the surface area of the coating layer 1 1 9.
• the power density of the device 10 is further optimized, by maintaining a low resistance.
• the surface area of the coating layer 1 1 9 is determined by the BET methodology, which is well known in the art.
• the surface enhancement which is an indication of the optimization of the surface area of the coating layer 1 1 9, is determined according to the following equation:
• the surface enhancement values can be as large as 1 0,000 to 100,000.
• the coating layer 1 1 9 is porous, and its porosity could range between about five percent (5 %) and ninety-five percent (95%). Exemplary porosity range for efficient energy storage is between about twenty percent (20%) and twenty-five percent (25%).
• the main device resistance is due to the carbon coating layer.
• most of the device resistance is due to the electrolyte, which has a higher resistance than that of the porous conductive coating layer.
• the preunit device 1 0 When the preunit device 1 0 is filled with an electrolyte, it becomes ready to be charged to become device 10A.
• the main criterion for the electrolyte is to be ionically conductive and have bipolar characteristics.
• the boundary or interface region between the electrode and the electrolyte is referred to in the field, as the "double layer", and is used to describe the arrangement of charges in this region.
• Double layer is used to describe the arrangement of charges in this region.
• a more detailed description of the double layer theory is found in "Modern Electrochemistry", by Bockris et al, volume 2, sixth print, chapter 7 (1 977).
• the surface area of the coating layer affects the capacitance of the device 1 0A. If for instance, the surface enhancement factor is between 1 ,000 to 20,000, and the double layer capacitance density is between about 1 0 to 500 microfarad per cm 2 of the interfacial surface area (i.e. the BET surface area), then surface enhancement capacitance densities of about 0.1 to 10 farads/cm 2 electrode are obtained.
• the high surface area (porous) electrically conducting coating material is applied onto the support material.
• the porous coating material may originate from various reactive precursors in a solution or a sol-gel composition. Numerous methods of application of these precursor compositions are feasible; but not limited to the following.
• a curing, hydrolysis and/or pyrolysis process usually is performed to form the coating on the support. Pyrolysis of the metal salts is usually done in a controlled atmosphere (nitrogen, oxygen, water, and/or other inert and oxidative gasses) by means of a furnace and/or an infrared source.
• (a) Dip Coating The electrode or support, is dipped into a solution or sol-gel, coating the support with a precursor coating, and subsequently cured by pyrolytic and other methods. Optionally, this process may be repeated to increase layer thickness.
• a preferred procedure is to dip the support material in a metal chloride/alcohol solution followed by pyrolysis at between about 250 and 500 ° C for 5-20 min in a 5-100% oxygen atmosphere.
• a final pyrolysis treatment at 250-450 ° C is done for 1 -10 hr.
• Another procedure is to create a sol-gel solution with ruthenium, silicon, titanium and/or other metal oxides and coat the support as above.
• the pH, water concentration, solvent, and/or the presence of additives like oxalic acid, formamide, and/or surfactants the discharge frequency characteristics of the coating may be adjusted.
• High relative humidity during the pyrolysis step can be used to complete the conversion of starting material to oxide at lower temperatures, a procedure is to pyrolyze at about 300°C without control of humidity. However, an additional procedure is to maintain the relative humidity above about 50% during this pyrolysis at temperatures below 350°C or below.
• a preferred method for dip coating thin (e.g. 1 mil) support structures is to use a wire frame structure 300 to keep the support material 1 18 under tension ( Figures 15 and 15A).
• the wire frame structure 300 includes at least two (2) wires 301 and 301 A of lengths larger than the width of the support material 1 18.
• Each wire 301 and 301 A includes a single length of wire which is tightly coiled at each end about 360° to form two coils 302 and 303. The coils are wrapped so the ends of the coil are around 1 cm above the plane of the wire.
• the coils 302 and 303 are placed through holes 304 and 305, respectively, in the support materials.
• the holes 304 and 305 are located at two corners on an adjacent side of the support material.
• the coating solution is applied to the support by a spray method, cured, and optionally repeated to increase the thickness.
• a preferred procedure is to apply the coating solution to the substrate at a temperature of 0- 1 50 ° C by means of an ultrasonic or other spray nozzle with a flow rate of around 0.1 -5 ml/min in a carrier gas composed of nitrogen, oxygen and/or other reactive and inert gases.
• the coating characteristics can be controlled by the partial pressure of oxygen and other reactive gasses.
• doctor Blading - A doctor blading methodology is used to apply the precursor coating, and optionally repeated.
• Electrophoretic Deposition The porous coating or precursor coating is applied to the support by electrophoretic deposition techniques, and optionally repeated.
• the porous coating or precursor coating may be applied by chemical vapor deposition techniques known in the art.
• Electrode Pretreatment It has been found that a number of pretreatments (conditioning) or combinations thereof are useful to improve the electrical characteristics of the coating (e.g. electrochemical inertness, conductivity, performance characteristics, etc.). These treatments include for example:
• a method procedure is to contact the coated electrode with water saturated steam in a closed vessel at between 1 50 and 325 ° C for between 1 to 6 hr. under autogenic pressure.
• the coated electrode is contacted one or more times with a reactive gas such as oxygen, ozone, hydrogen, peroxides, carbon monoxide, nitrous oxide, nitrogen dioxide, or nitric oxide at between ambient temperature and 300 ° C at a reduced pressure or under pressure.
• a reactive gas such as oxygen, ozone, hydrogen, peroxides, carbon monoxide, nitrous oxide, nitrogen dioxide, or nitric oxide
• a preferred procedure is to contact the coated electrode with flowing ozone at between about 5-20 weight percent in air at between ambient and 100 ° C and 0.1 -2000 torr pressure for 0.1 -3 hr.
• Supercritical Fluid - The coated electrode is contacted with a supercritical fluid such as carbon dioxide, organic solvent, and/or water.
• a supercritical fluid such as carbon dioxide, organic solvent, and/or water.
• a preferred procedure is treatment with supercritical water or carbon dioxide for 0.1 -5 hrs by first raising the pressure then the temperature to supercritical conditions.
• Electrochemical-The coated electrode is placed in a sulfuric acid electrolyte and contacted with an anodic current sufficient to evolve oxygen gas and subsequently with a cathodic current.
• the electrode is contacted with 10mA/cm 2 in 0.5M sulfuric acid for about 5 min, to evolve oxygen gas.
• the electrode is then switched to a cathodic current and the open circuit potential is driven back to a potential of between about 0.5V - 0.75V, preferably between 0.5 and 0.6 and more preferably about 0.5 V (vs. NHE) with out hydrogen gas evolution. 5.
• Reactive iiquid-The coated electrode is contacted with an oxidizing liquid such as aqueous solutions of hydrogen peroxide, ozone, sulfoxide, potassium permanganate, sodium perchlorate, chromium (VI) species and/ or combinations thereof at temperatures around ambient to 100 ° C for 0.1 -6 hr.
• an oxidizing liquid such as aqueous solutions of hydrogen peroxide, ozone, sulfoxide, potassium permanganate, sodium perchlorate, chromium (VI) species and/ or combinations thereof at temperatures around ambient to 100 ° C for 0.1 -6 hr.
• a preferred procedure uses a 1 0-100 mg/l aqueous solution of ozone at 20-50 ° C for around 0.5-2 hr. followed by an aqueous wash.
• An additional procedure is to treat the coated electrode in a chromate or dichromate solution.
• a number of methods are available to obtain electrical insulation and properly defined spacing between the electrodes. These methods include, for example: 1 . Microprotrusions - The separator 1 25 and 1 27 between the coatings
• 1 1 9 and 1 20 includes a matrix of small (in area and height) protrusions, i.e. 1 25 and 1 27, on the surface of at least one side of the electrode.
• These microprotrusions may be composed of thermosets, thermoplastics, elastomers, ceramics, or other electrically insulating materials.
• the separator between the electrodes is a thin, substantially open structure material such as glass.
• a preferred material is 0.001 -0.005 in (0.00254 to 0.01270 cm) porous glass sheet available from Whatman Paper Ltd located in Clifton, NJ.
• Air space - The separator between the electrodes is also an air space which is subsequently occupied by the non-aqueous or aqueous electrolyte.
• the materials used for the gaskets include any organic polymer which is stable in the electrical/chemical environment, and to the processing conditions. Suitable polymers include, for example polyimide, TEFZEL ® , polyethylene (high and low density), polypropylene, other polyolefins, polysulfone, KRATON ® other fluorinated or partly fluorinated polymers or combinations thereof.
• the gasket may be applied as a preformed material, screen printed, or by other methods.
• the cord (1 1 7 A, 1 17B and 1 17C) for the creation of the fill ports is of any suitable material having some specific properties, e.g., it is different from the gasket materials, has a higher melting temperature (Tm) than the gasket material, and does not melt, flow or adhere to the gasket material under the heating conditions described herein.
• Tm melting temperature
• glass, metal, ceramic, and organic polymers or combinations thereof are used.
• a stack is created by starting with an endplate and alternating gasket material, cord, electrode, gasket, cord electrode until the desired number of cells are created finishing with a second endplate, and optionally with a gasket material on the top outside of the stack.
• the stack is heated under pressure to cause reflow of the gasket material, adhering and sealing the perimeter of the electrode materials to the adjacent electrode in the stack; thereby, creating isolated celis and an assembled stack unit. This is done in an inert atmosphere.
• RFIDH Radio Frequency Induction Heating
• RH Radiant Heating
• a preferred method is to use 1 -100 ⁇ m radiation at 0.5-10 watts/cm 2 for 1 -20 min.
• Conductive and/or convective heating in a furnace, optionally in an inert atmosphere, is used to heat the stack to cause reflow of the gasket material.
• step (J) Post-Conditioning 1 A number of post-conditioning reactive gas treatments of the stack or assembled stack or combinations thereof are useful to improve the overall and long term electrical characteristics of the electrode and resulting device. These include either before step (H) and/or after step (I) treatment with hydrogen, nitric oxide, carbon monoxide, ammonia, and other reducing gasses or combinations thereof at between ambient temperature and the Tm of the gasket material at a reduced pressure or under pressure.
• a second post conditioning commonly done is to adjust the open circuit potential of the electrode after step (F) and stack the electrode in an inert atmosphere (e.g. Ar, N 2 ). This is done by using a cathodic current without hydrogen evolution.
• an inert atmosphere e.g. Ar, N 2
• the dry preunit is filled with an ionically conducting aqueous or non-aqueous electrolyte.
• a preferred electrolyte is approximately 30% sulfuric acid in water due to the high conductivity.
• Non-aqueous electrolytes based on propylene and ethylene carbonate are also used to obtain larger than 1 .2V/cell potentials.
• a preferred procedure for filling the dry preunit with liquid electrolyte is to place the preunit in a chamber, evacuate the chamber between about 1 torr to 1 microtorr, preferably about 250 mtorr to less than 1 torr, and introduce the electrolyte; thereby, filling the cell gaps with electrolyte through the fill ports.
• the preunit may be placed in the electrolyte and a vacuum pulled; thereby causing the gas in the cell gaps to be removed and replaced by the electrolyte.
• non liquid based electrolytes e.g. solid and polymer
• the electrode is coated with the electrolyte before reflow and a fill port is not required.
• the fill ports are sealed by reflowing an additional film of polymer the same or different over the openings to create a sealed device. This is commonly done with an induction heater, which locally heats the film over the fill port opening. (M) Burn-In
• the device is brought to full charge usually by charging the device in 0.1 V/cell steps at a charging current of about 4 mA/cm 2 .
• the oxide coating is removed from the exposed faces of the endplates or the endplates may be coated only on one side. Clean nickel foil leads or copper plates make electrical connection to the exposed faces by bonding them together with a conductive silver epoxy. Optionally, the oxide coating is present.
• Lugs - Threaded titanium nuts are welded to the thick titanium endplates before coating. Electrical connection to the titanium nuts is achieved by screw attachment. 4. Press Contacts - The oxide is removed or the endplates may be coated only on one side from the exposed side of the endplates before assembly into the device stack.
• the bare support material e.g. titanium, is reverse sputtered to clean the surface, being careful not to overheat the substrate. The clean surface is then sputtered with titanium to lay down a clean adhesion layer, followed by gold.
• the gold acts as a low contact resistance surface to which electrical contact can be made by pressing or by wire bonding.
• the device resistance is measured at 1 kHz.
• the device capacitance is determined by measuring the coulombs needed to bring the device to full charge at a charging rate of around 4 mA/cm 2 of electrode area.
• Leakage current is measured as the current needed to maintain a full charge after 30 min. of charging.
• These devices may be made in various configurations depending on the desired application. By adjusting the device voltage, cell voltage, electrode area, and/or coating thickness in a rational manner, devices made to fit defined and predetermined specifications are constructed.
• the electrode capacitance density (C in units of F/cm 2 ) is roughly 1 F/cm 2 for every 10 ⁇ . of coating. Therefore, for large capacitance values a thicker coat is used.
• the device capacitance (C) is equal to the electrode capacitance density times the electrode area (A in units of cm 2 ) divided by two times the number of cells (n) (equation 1 ).
• the leakage current (i") is proportional to the electrode area, while the equivalent series resistance (ESR) is inversely proportional to the electrode area (eqn. 2). Typical values for i" are less than 20 //A/cm 2 .
• the total number of cells in a device (n) is equal to the cell voltage (V) divided by the total device voltage (V) (eqn. 3). Cell voltages up to about 1 .2 V can be used with aqueous based electrolytes.
• the device height (h), based on a cell gap (h') and a support thickness (h"), is determined from the number of cells and the electrode capacitance density in units of cm by equation 4.
• the device ESR is a function of the number of cells times the cell gap (h') times the resistivity of the electrolyte (r) times a factor of about 2 divided by the area (equation 5).
• eqn. 1 C C'A/2n eqn. 2 i" ⁇ A ⁇ 1 /ESR eqn. 3
• n V/V eqn. 4
• h/cm n(0.002C' + h' + h") eqn. 5
• Devices are constructed to meet the requirements of various applications by considering the voltage, energy, and resistance requirements. The following examples are not meant to be limiting in any way: For electric vehicle applications about a 100 KJ to 3 MJ device is used. A large voltage (about 100 to 1000 V) large energy (1 -5 F/cm 2 ) storage device is used with an electrode area of about 1 00 to 10,000 cm 2 .
• a 10 to 80 KJ device For electrically heated catalyst applications for reduction of automobile cold start emissions about a 10 to 80 KJ device is used. This device is about 1 2 to 50 V constructed with around 100 to 1000 cm 2 area electrodes of 1 -5 F/cm 2 .
• a device consisting of several devices in parallel can be constructed to meet the electrical requirements.
• a screenprinting method 250 with respect to Figures 7 and 8, the focus of the method 250, is to produce a series of microprotrusions 1 25 and 1 27 on the surface of the coating layers, to act as a space separator in electrical storage devices, such as a capacitor or a battery, in general, and in the dry preunit energy storage device 10, in particular.
• the substrate is usually a thin metal such as titanium, zirconium, or alloys thereof.
• the substrate is usually in the shape of a thin metal plate as is conventional in the capacitor art.
• the substrate is coated on one or both sides with a porous carbon compound or a porous oxide coating. This step is accomplished by methods conventional in the art.
• the oxide coating serves as the charge storage area for the device.
• a stacked set of battery electrodes e.g., lead for lead acid
• electrolytic capacitor electrodes e.g., alumina and tantalum
• the epoxy microprotrusions accomplish the desired uniform separation.
• Sample Holding The coated thin flat substrate needs to be secured (or held), so that the formation of the microprotrusions is precise and accurate on the flat surface of the substrate.
• an electrode holder 275 is particularly important. If a strong vacuum is pulled on a thin sheet, often reverse dimples are formed in the thin sheet which cause significant undesirable changes in the physical and electrical properties of the final device.
• the electrode holder 275 includes a porous ceramic holder 276, which is useful because the pore size is small enough that the dimples do not appear when a mild or stronger vacuum is pulled.
• the flat ceramic surface of the ceramic holder 276 must be in intimate contact with the surface of the electrode 1 1 1 A, under conditions which do not deform the metal or disrupt the coating present.
• the vacuum used with the porous ceramic is at least 25 in mercury. Preferably the vacuum is between about 25 and 30 in., especially 26 and 29 in.
• the ceramic substrate needs to be flush with the surface of any mechanical holder to assure that uniform extrusion of the epoxy through the screen openings occurs.
• Flush in this context means that the flat surface of the holder and the surface of the coating for electrical storage differ from each other by between about ⁇ 5 mil (0.01 27 cm) deviation or less from level per 6 linear in.
• the electrode holder 275 further includes a metal frame 277, which should also be as flush (flat) as possible so that uniformly sized protrusions are formed from one end of the electrode to the other.
• the electrode holder 275 can be purchased from a number of commercial sources for example from Ceramicon Designs, Golden, Colorado. Alternatively, the sample holder 276 can be manufactured using commercially available metals, alloys or ceramics. Usually, a 5 in ( 1 2.7 cm) by 7 in ( 1 7.78 cm) coated sheet electrode is formed.
• the metal holder 277 has a plurality of strategically located pins, such as the three pins 278, 279 and 280, which are used to align and position the electrode 1 1 1 A, using a plurality of corresponding holes 281 , 282 and 283, respectively.
• the holes 281 , 282 and 283 are usually as close to the peripheral edges of the electrode 1 1 1 A, as possible to conserve useful electrode surface. Alternatively, no alignment holes are used, and the pins are used to align the electrode edges.
• a stencil (not shown) having a predetermined open pattern, is stretched and secured in a conventional screen printing frame (not shown). The screen mesh is removed.
• the epoxy components are mixed and the fluid epoxy is placed on the surface of the stencil, then spread to obtain an even applied coat. This can be accomplished using a pressure bar, doctor bar or a squeegee.
• the stencil is then carefully removed leaving the fluid epoxy protrusions on the surface of the oxide.
• the epoxide protrusions are then cured using ambient, accelerated heat at from between 100 to 1 50°C. or light.
• the electrode having microprotrusions is then combined with other electrodes, and assembled in a wet process or a dry process. If a dry process is used, the dry unit 1 0 is then back filled with electrolyte, when it is to be charged.
• the cured epoxy does not react with the liquid electrolyte eventually used in the fabrication of the capacitor having multiple layers of electrodes.
• the cured microprotrusions then perform their function by keeping the spacing between the electrodes uniform.
• the edges of the flat surface of the electrode have protrusions 1 25 that are closer together than those protrusions 1 27 in the active or central portion of the electrode. These protrusions 1 25 increase the support at the edges to maintain uniform separations. Alternatively, bars may be used.
• thermosets thermoelastomers, or photo curable epoxies or epoxy derivatives conventional in the art can be used.
• microprotrusion pattern elements can be used such as squares, lines, crosses, etc. Specifically, bars on the perimeter can add mechanical support.
• the screen may be heated, if necessary to bring the resin flowable epoxy to a temperature when its viscosity becomes suitable for printing for a short time.
• This heating step followed by screen printing of the flowable epoxy resin must be performed quickly because the working time for the epoxy is significantly reduced.
• the electrical storage devices produced having the microprotusions 1 25 and 1 27 are useful as batteries, capacitors and the like. Photolithographic Production of Microprotrusions
• the focus of the present method is to produce a series of microprotrusions on the surface, or alloys of the electrode substrate, using photolithography, with respect to Figures 10, 1 1 and 12.
• the substrate is usually in the shape of a thin metal plate as is conventional in the capacitor art.
• a photo resist film 381 is applied to the surface of the electrode 1 1 1 A, either by vacuum lamination using the commercially available Dynachem ConforMASK film applicator, and Dynachem vacuum applicator Model 724/730, or by passing the photo resist film 381 and electrode 1 1 1 A through a pair of heated rollers 384 and 385.
• Exposure is done using a standard 1 -7kW UV exposure source, such as mercury vapor lamps 389.
• the ConforMask film applicator is developed using standard conditions such as 0.5-1 .0% sodium or potassium carbonate monohydrate in either a developing tank or a conveyorized aqueous developer.
• a developing tank or a conveyorized aqueous developer may be neutralized in a dilute 10% sulfuric acid solution. This removes all the unwanted unreacted film to leave the reacted microprotrusions adhered to the electrode surface.
• the resulting material is put through a final curing process involving both UV irradiation and thermal treatment utilizing conventional UV curing units and convection air ovens.
• the multiple electrodes are assembled to produce for instance a capacitor, as described above.
• the microprotrusions accomplish the desired uniform separation.
• the energy storage device 10A has a multitude of applications, as a primary or back up power supply, and/or as a capacitor.
• the size is from 0.1 volt to 100,000 volts or 0.1 cm 3 to 10 6 cm 3 .
• Typical voltage ranges may include combinations of uses in automotive and other applications.
• Magnetic Resonance Imaging MRI
• the support structure is prepared by etching a 1 mil (0.00254 cm) titanium sheet with 35% HN0 3 /1 .5 % HF at 60 ° C for 5 min.
• the end plates are 5 mil (0.01 27 cm) titanium.
• the oxide coating solution is 0.2 M ruthenium trichloride trihydrate and 0.2 M niobium pentachloride in tert-butanol (reagent grade).
• the etched Ti sheets are dip-coated by immersion into the solution at ambient conditions.
• the coated sheet is submerged into the solution, held for about 1 sec and then removed.
• the oxide is dried at 70 ° C for 10 min, pyrolyzed at 350 ° C for 10 min and removed to cool to ambient temperature all in ambient atmosphere.
• the dip-coating steps are repeated for 10 coats (or any desired number) rotating the Ti sheet so as to dip with alternate sides down. A thickness of about ten microns is achieved.
• the fully coated sheet is final annealed at 350 "C for 3 hrs in ambient atmosphere.
• Microprotrusions are screen printed on one side of the electrode, as described below, in greater detail, under the heading "SCREEN PRINTING".
• the epoxy compound is EP21 AR from Masterbond, of Hackensack, New Jersey.
• the epoxy protrusions are cured at 150 °C for 4 hr. in air.
• the coated electrodes are next die-stamped to the desired shape.
• a modified high density polyethylene 1 .5 mil (0.00381 cm) thick by 30 mil (0.0762 cm) wide with outside perimeter the same as that of the electrode is placed on the electrodes on the same side as the microprotrusions and impulse heat laminated.
• the HDPE is grade PJX 2242 from Phillips-Joanna of Ladd, Illinois.
• a second HDPE gasket is placed on the first gasket sandwiching the cord between the two gaskets. The second gasket is impulse heated to adhere to the first gasket and to fix the cord in place.
• Electrode/microprotrusion/gasket/cord/gasket units are stacked in a non- metallic (ceramic) alignment fixture beginning with a 5 mil (0.01 27 cm) end plate unit to the desired number of cells and ending with a plain 5 mil (0.0127 cm) end plate with the cords arranged such that the location is staggered-left, center, right in a three unit repeating cycle (end perspective).
• Light pressure is applied to the top of the stack through a ceramic piston block to maintain uniform alignment and contact throughout the stack.
• a radio frequency induction heater (2.5 kW) is used to heat the stack.
• the stack was placed centrally in the three turn, 3 in (7.62 cm) diameter coil and heated for 90 seconds at a power setting of 32 % .
• the fused unit is allowed to cool to ambient temperature.
• the cords are removed by carefully pulling the exposed ends of the cord to leave the open fill ports.
• the support structure is prepared by etching a 1 mil (0.00254 cm) titanium sheet with 50% HCI at 75 ° C for 30 min.
• the end plates are 2 mil (0.00508 cm) titanium.
• the oxide coating solution is 0.3 M ruthenium trichloride trihydrate and 0.2 M tantalum pentachloride in isopropanol (reagent grade).
• the etched Ti sheets are dip-coated by immersion into the solution at ambient conditions.
• the coated sheet is submerged into the solution, held for about 1 sec and then removed.
• the oxide is dried at 70 ° C for 10 min. in ambient atmosphere, pyrolyzed at 330 ° C for 1 5 min in a 3 cubic feet per hrs. flow of 50 vol. % oxygen and 50 % nitrogen, and removed to cool to ambient temperature in ambient atmosphere.
• the dip-coating steps are repeated for 30 coats (or any desired number) rotating the Ti sheet so as to dip with alternate sides down.
• the fully coated sheet is final annealed at the above conditions for 3 hr.
• VITON ® microprotrusions are screen printed on one side of the electrode, as described below, in greater detail, under the heading "VII. SCREEN PRINTING" .
• the VITON ® protrusions are cured at 1 50 ° C for 30 min. in air.
• the coated electrodes are next die-stamped to the desired shape.
• a modified high density polyethylene 1 .0 mil (0.00254 cm) thick by 20 mil (0.0508 cm) wide with outside perimeter the same as that of the electrode is impulse heat laminated to both sides of the electrode.
• the HDPE is grade PJX 2242 from Phillips-Joanna of Ladd, Illinois.
• One cord 1 mil (0.00254 cm) diameter TEFLON ® coated tungsten wire is placed across the narrow dimension of the gasket and electrode surface and aligned between microprotrusions. The location of the cord is one of three positions centered, left of center, or right of center.
• Electrode/microprotrusion/gasket/cord/gasket units are stacked beginning with a 2 mil (0.00508 cm) end plate unit to the desired number of cells and ending with a plain 2 mil (0.00508 cm) end plate with the cords arranged such that the location is staggered-left, center, right in a three unit repeating cycle (end perspective) .
• the support structure is prepared by etching a 1 mil (0.00254 cm) titanium sheet with 50% Hcl at 75 °C for 30 min.
• the end plates are 10 mil (0.0254 cm) titanium.
• the oxide coating solution is 0.2 M ruthenium trichloride trihydrate and 0.2 M tantalum pentachloride in isopropanol (reagent grade).
• the etched Ti sheets are dip-coated by immersion into the solution at ambient conditions.
• the coated sheet is submerged into the solution, held for about 1 sec and then removed.
• the oxide is dried at 70 ° C for 10 min, pyrolyzed at 300 ° C for 5 min and removed to cool to ambient temperature all in ambient atmosphere.
• the dip-coating steps are repeated for 10 coats (or any desired number) rotating the Ti sheet so as to dip with alternate sides down.
• the fully coated sheet is final annealed at 300 ° C for 3 hrs in ambient atmosphere.
• Microprotrusions are screen printed on one side of the electrode, as described below, in greater detail, under the heading "SCREEN PRINTING".
• the epoxy compound is grade EP21 AR from Masterbond, Hackensack, NJ.
• the epoxy protrusions are cured at 1 50 ° C for 4 hr. in air.
• the coated electrodes are next die-stamped to the desired shape.
• a modified high density polyethylene 1 .5 mil (0.00381 cm) thick by 30 mil (0.0762 cm) wide with outside perimeter the same as that of the electrode is placed on the electrodes on same side as the microprotrusions and impulse heat laminated.
• the HDPE® is grade PJX 2242 from Phillips-Joanna of Ladd, Illinois.
• One cord 1 mil (0.00254 cm) thick by 10 mil (0.0254 cm) wide is placed across the narrow dimension of the gasket and electrode surface and aligned between microprotrusions. The location of the cord is one of three positions centered, left of center, or right of center.
• a second HDPE ® gasket is placed on the first gasket sandwiching the cord between the two gaskets.
• the second gasket is impulse heated to adhere to the first gasket and to fix the cord in place.
• Electrode/microprotrusion/gasket/cord/gasket units are stacked beginning with a 10 mil (0.0254 cm) end plate unit to the desired number of cells and ending with a plain 10 mil (0.0254 cm) end plate with the cords arranged such that the location is staggered-left, center, right in a three unit repeating cycle (end perspective).
• the cords are removed by carefully pulling the exposed ends to leave the open fill ports.
• the support structure is prepared by etching a 1 mil (0.00254 cm) titanium sheet with 50% HCI at 75 " C for 30 min.
• the end plates are 5 mil (0.01 27 cm) titanium.
• the oxide coating solution is 0.2 M ruthenium trichloride trihydrate and 0.2 M Ti(di-isopropoxide)bis 2,4-pentanedionate in ethanol (reagent grade) .
• the etched Ti sheets are dip-coated by immersion into the solution at ambient conditions. The coated sheet is submerged into the solution, held for about 1 sec and then removed.
• the oxide is dried at 70 ° C for 10 min, pyrolyzed at 350 ° C for 5 min in oxygen and removed to cool to ambient temperature all in ambient atmosphere.
• the dip-coating steps are repeated for 30 coats (or any desired number) rotating the Ti sheet so as to dip with alternate sides down.
• the fully coated sheet is final annealed at 350 ° C for 3 hrs in an oxygen atmosphere.
• Microprotrusions are thermally sprayed through a mask on one side of the electrode.
• the thermal spray material is TEFLON ® from E.I. DuPont de Nemours & Co., Wilmington, Delaware.
• the TEFLON 8 protrusions are cured at 300 ° C for 0.5 hr. in air.
• the coated electrodes are next die-stamped to the desired shape.
• a modified high density polyethylene 1 .5 mil (0.00381 cm) thick by 30 mil (0.0762 cm) wide with outside perimeter the same as that of the electrode is placed on the electrodes on same side as the microprotrusions and impulse heat laminated.
• the HDPE is grade PJX 2242 from Phillips-Joanna of Ladd, Illinois.
• One cord (TEFZEL ® ) 1 mil (0.00254 cm) thick by 10 mil (0.0254 cm) wide is placed across the narrow dimension of the gasket and electrode surface and aligned between microprotrusions. The location of the cord is one of three positions centered, left of center, or right of center.
• a second HDPE ® gasket is placed on the first gasket sandwiching the cord between the two gaskets.
• the second gasket is impulse heated to adhere to the first gasket and to fix the cord in place.
• (F) Stacking Electrode/microprotrusion/gasket/cord/gasket units are stacked beginning with a 5 mil (0.01 27 cm) end plate unit to the desired number of cells and ending with a plain 5 mil (0.01 27 cm) end plate with the cords arranged such that the location is staggered-left, center, right in a three unit repeating cycle (end perspective).
• the gasket is reflowed in nitrogen at 1 90 ° C for 30 min. to reflow the thermoplastic.
• the unit is cooled in nitrogen to ambient temperature.
• (H) Cord Removal The cords are removed by carefully pulling the exposed ends to leave the open fill ports.
• EXAMPLE 5 Alternative Fabrication of Dry Preunit (A) Coating Method
• the support structure is prepared by etching a 0.8 mil (0.002032 cm) zirconium sheet with 1 %HF/20% HN0 3 at 20 " C for 1 min.
• the end plates are 2 mil (0.00508 cm) zirconium.
• the oxide coating solution is 0.2 M ruthenium trichloride trihydrate and 0.1 M tantalum pentachloride in isopropanol (reagent grade).
• the etched Ti sheets are dip-coated by immersion into the solution at ambient conditions. The coated sheet is submerged into the solution, held for about 1 sec and then removed.
• the oxide is dried at 85 ° C for 10 min, pyrolyzed at 31 0 ° C for 7 min and removed to cool to ambient temperature all in ambient atmosphere.
• the dip-coating steps are repeated for 10 coats (or any desired number) rotating the Ti sheet so as to dip with alternate sides down.
• the fully coated sheet is final annealed at 310 ° C for 2 hrs in ambient atmosphere.
• C Spacing Microprotrusions are thermally sprayed through a mask on one side of the electrode.
• the thermal spray material is TEFLON ® from E.I. DuPont de Nemours & Co., Wilmington, Delaware.
• the TEFLON ® protrusions are cured at 310 ° C for 1 .0 hr. in air.
• the coated electrodes are next die-stamped to the desired shape.
• One cord 1 mil (0.00254 cm) diameter TEFLON ® coated tungsten wire, is placed across the narrow dimension of the gasket and electrode surface and aligned between microprotrusions. The location of the cord is one of three positions centered, left of center, or right of center. A second polypropylene gasket is placed on the first gasket sandwiching the cord between the two gaskets.
• the second gasket is impulse heated to adhere to the first gasket and to fix the cord in place.
• Electrode/microprotrusion/gasket/cord/gasket units are stacked beginning with a 2 mil (0.00508 cm) end plate unit to the desired number of cells and ending with a plain 2 mil (0.00508 cm) end plate with the cords arranged such that the location is staggered-left, center, right in a three unit repeating cycle (end perspective).
• a dry preunit 10 may be filled with an electrolyte with the following procedure. Any of many possible dry preunit configurations may be used. (H) Back Fill
• the cords are removed manually to open the fill port.
• the stacked unit is placed into an evacuation chamber and evacuated to ⁇ 35 mtorr for 5 to 60 min.
• the liquid electrolyte 3.8 M H 2 S0 4 de-airated with nitrogen is introduced into the chamber and fills the evacuated space between the electrodes.
• the electrolyte filled preunit is removed from the chamber. It is rinsed with deionized water to remove excess electrolyte and dried.
• HDPE film (1 .5 mil
• the device is charged up to full charge beginning at 0.1 V/cell increasing by 0.1 V/cell until 1 V/ceil is obtained. (K) Testing
• the device is tested in the conventional manner, having 1 V/cell with leakage current of less than 25 ⁇ A/cm 2 , and a capacitance density per a cell of greater than about 0.1 F/cm 2 .
• a 10 V device has a height of no more than 0.05
• a 40 V device has a height of no more than 0.1 3
• a 100 V device has a height of no more than 0.27" .
• Performance characteristics for various device geometries and configurations based on a sulfuric acid electrolyte are presented in Table 1 .
• EXAMPLE 7 Alternative Backfill of Dry Preunit A dry preunit 10 may be filled with an electrolyte with the following procedure. Any of many possible dry preunit configurations may be used. (H) Back Fill
• the cords are removed to open the fill port.
• the stacked unit is placed into an evacuation chamber and evacuated to ⁇ 35 mtorr for 5 to 60 min.
• the liquid non-aqueous electrolyte 0.5 M KPF 6 in propylene carbonate de-airated with nitrogen is introduced into the chamber and fills the evacuated space between the electrodes.
• the device is charged up to full charge beginning at 0.1 V/cell increasing by 0.1 V/cell until 1 .5 V/cell is obtained. (K) Testing
• the device is tested in the conventional manner, having 1 .5 V/cell with leakage current of around 100 /A/cm 2 , and a capacitance density of around 4 Mf/cm 2 for a 10 cell device.
• EXAMPLE 8 DEVICE POST-TREATMENT CONDITIONS
• Table 3 The following is a list of the electrical properties (Table 3) of devices using various gas postconditioning techniques to adjust the electrode rest potential so that charging to at least 1 V/cell on multicell devices filled with 4.6 M sulfuric acid electrolyte is possible and reduced leakage currents are observed.
• This treatment is done before, during, and/or after reflow of the gasket material.
• an inert gas such as nitrogen or argon during reflow.
• the tabs were removed before treatment.
• the atmosphere is evacuated and filled with the reactive gas periodically.
• a 325 mesh stainless steel screen is stretched on a standard screen printing frame. To this screen is edge glued (Dexter Epoxy 608 clear) to a smaller 1 -1 .5 mil (0.00254 to 0.00381 cm) thick brass sheet which has holes (6.3 mil (0.01 6 cm) diameter) drilled or etched to the desired pattern. The screen mesh is removed from the area covered by the brass sheet leaving the brass sheet edge glued to the screen mesh attached to the frame.
• the filled epoxy having the desired viscosity is available by purchase order from Master Bond, Inc. of Hackensack, New Jersey.
• the epoxy is prepared as per instructions.
• the useful lifetime as a flowable fluid is about 30 min.
• Constant temperature and humidity of the epoxy are important to assure an even applied coat. Typical conditions are about 40-70% relative humidity and a temperature of about 20-25 °C.
• (E) Printed epoxy pattern An array of epoxy bumps essentially 1 mil (0.00254 cm) in height and about 7.5 mil (0.01 9 cm) in diameter are produced.
• a typical pattern on an electrode consists of an array of microprotrusions deposited on 40 mil (0.1 01 6 cm) center-to-center spacing.
• the density of microprotrusions at the perimeter of the electrode is increased by decreasing their center-to-center spacing to 20 mil (0.508 cm).
• the screen printed epoxy configuration is cured at 1 50°C for a minimum of 4 hr.
• the screen is then flipped, epoxy applied to the top side of the screen, a MYLAR ® sheet placed over the area and the epoxy smoothed.
• the MYLAR ® sheet on the top side of the screen is then removed.
• the screen-stencil assembly is then placed into a 1 20°C oven with ambient atmosphere for 5 min to cure the epoxy.
• the epoxy can be cured by setting at ambient temperature for 30-60 min.
• any heat stable thermoset adhesive e.g. an epoxy resin
• the epoxy is cured in the oven for 5 min.
• the resulting item is a stencil stretched taut by the screen, ready for printing.
• the epoxy is prepared as per the product instructions.
• the useful lifetime as a flowable fluid is about 30 min.
• (E) Printed epoxy pattern An array of epoxy bumps essentially about 1 to 1 .25 mil (0.00254 to 0.0031 6 cm) in height and about 7.5 mil (0.01 9 cm) in diameter are produced.
• a typical pattern on an electrode consists of an array of microprotrusions deposited on 40 mil (0.1 cm) center-to-center spacing. In addition, the density of microprotrusions around the perimeter of the electrode is increased by decreasing their center-to-center spacing to 20 mil (0.0508 cm).
• the screen printed epoxy configuration is cured at 1 50°C for 4 to 1 2 hrs. in an ambient atmosphere.
• EXAMPLE 1 1 ALTERNATIVE SCREEN PRINTING PARAMETERS
• Separator Bumps -- Separator bumps range in height from .001 to .004 in. (.00254 to 0.0101 6 cm) and widths of .006 to .01 2 in. (.01 524 to .03038 cm). Separator bumps may take the form of dots, squares, rectangles or a composite of these shapes. The widths of the bumps increase as the bump height is increased.
• (B) Separator Pattern - Two patterns are utilized on an electrode substrate, the Active Field Area and the Bounding Border Area.
• the AFA has the separator bumps located on .040 by .040 in. (.101 6 by .101 6 cm) center to center spacing and are normally dots.
• the BBA has an increased bump density with a .020 by .020 in. (.0508 by .0508 cm) center to center spacing. Rows of rectangles alternate between arrays of dots.
• Electrode Vacuum Plate (Workholder) -- A porous ceramic plate (Ceramicon Designs, Golden, Colorado, P-6-C material) trimmed .050 smaller than the electrode perimeter is fitted and epoxied into an aluminum plate designed to fit the screen printer. The top and bottom surfaces are ground flush and parallel. Multiple pins are inserted around the centered electrode edge creating a corner stop for placement of the electrode substrate.
• the filled epoxy having the desired viscosity is available by purchase order from Master Bond, Inc. of Hackensack, New Jersey.
• the epoxy is prepared as per instructions.
• the useful lifetime as a flowable fluid is about 30 min.
• EXAMPLE 1 2 Hot Roller Photolithographic Production of Microprotrusions (A) The ConforMASK® 2000 high conformance solder mask of 1 .5 mil (0.0038 cm) in thickness is cut to the same size as the electrode. (B) The photo resist film 381 is applied by placing the ConforMASK ® film on the electrode material surface 1 1 1 A, after removing a release sheet 382 between the phoio resist film 381 and the electrode 1 1 1 A, and passing the laminate through heated rollers (384 and 385), at 1 50°F, to adhere the photoresist film 381 to the electrode surface 1 1 1 A. A polyester cover sheet 382A on the outside of the photo resist film 381 is then removed.
• a dark field mask 387 containing rows of transparent holes (openings 388) is placed on the photo resist 381 .
• a typical pattern consists of an array of holes 6 mil (0.021 2 cm) in diameter 40 mil (0.1 cm) center-to-center spacing with a higher density (20 mil (0.0508 cm) center-to-center) for three rows on the perimeter of the electrode.
• the finished electrode 1 1 1 A is used directly, or is treated, as described above.
• EXAMPLE 1 3 Vacuum Lamination of Photo resist
• A The ConforMASK ® 2000 high conformance solder mask of 2.3 mil (0.0058 cm) in thickness is cut slightly larger than the electrode.
• B The photo resist film is 381 vacuum laminated to the electrode 1 1 1 A, and onto a supporting backing plate using standard operating conditions (1 60°C, 0.3 mbars) using a Dynachem vacuum applicator model 724 or 730.
• the polyester cover sheet 382A is removed.
• the dark field mask 387 containing rows of transparent holes 388 is placed on the photo resist film 381 .
• a typical pattern includes an array of holes 6 mil
• a final cure of the microprotrusion standoffs is done in a two step process. First, the microprotrusions are exposed to UV light in a Dynachem UVCS 933 unit and then placed in a forced air oven at 300-310°F for 75 min.
• the finished electrode is used directly or further treated as described above.
• a 25 wt % cetyltrimethyl ammonium chloride in water solution may also be used to modify the pore diameter of the resulting coating.
• EXAMPLE 1 5 Thermal Elastomeric Gasket An alternative construction methodology is to sandwich a thermal elastomer gasket (e.g. KRATON ® ) between the two HDPE gaskets. Device characteristics are similar to those previously described.
• a thermal elastomer gasket e.g. KRATON ®
• EXAMPLE 16 Inclusion of Second Material to Accommodate Electrolyte Volume Increases A porous hydrophobic material is added to each cell to accommodate any volume increase of the electrolyte due to an increase in temperature. This material is placed in the cell as either a gasket material inside the perimeter
• HDPE gasket or as a disk replacing part of the separator material.
• a common material used is a PTFE material from W.L. Gore & Associates, Inc. 1 -3 mil thick.
• the PTFE material has water entry pressures from 20 to 100 psi.
• the electrodes are placed in 1 M sulfuric acid and the open circuit potential is adjusted to about 0.5V (vs HHE) using cathodic current with no hydrogen evolution.
• the electrodes are transferred submerged in deionized water to an inert atmosphere

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