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WO2018136176A1 - Cellules électrochimiques à électrolyte mobile - Google Patents

Cellules électrochimiques à électrolyte mobile Download PDF

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Publication number
WO2018136176A1
WO2018136176A1 PCT/US2017/066558 US2017066558W WO2018136176A1 WO 2018136176 A1 WO2018136176 A1 WO 2018136176A1 US 2017066558 W US2017066558 W US 2017066558W WO 2018136176 A1 WO2018136176 A1 WO 2018136176A1
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WIPO (PCT)
Prior art keywords
electrode
electrolyte
membrane
galvanic
electrochemical cell
Prior art date
Application number
PCT/US2017/066558
Other languages
English (en)
Inventor
Halbert P. Fischel
Original Assignee
Global Energy Science, Llc
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
Priority claimed from US15/408,940 external-priority patent/US10522856B2/en
Application filed by Global Energy Science, Llc filed Critical Global Energy Science, Llc
Publication of WO2018136176A1 publication Critical patent/WO2018136176A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04276—Arrangements for managing the electrolyte stream, e.g. heat exchange
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-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
    • H01G11/10—Multiple hybrid or EDL capacitors, e.g. arrays or modules
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-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
    • H—ELECTRICITY
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    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-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
    • H01G11/54—Electrolytes
    • H01G11/58—Liquid electrolytes
    • H—ELECTRICITY
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    • 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
    • H01G11/66—Current collectors
    • H01G11/70—Current collectors characterised by their structure
    • H—ELECTRICITY
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    • 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
    • H01G11/74—Terminals, e.g. extensions of current collectors
    • H—ELECTRICITY
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    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-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
    • H01G11/78—Cases; Housings; Encapsulations; Mountings
    • H01G11/82—Fixing or assembling a capacitive element in a housing, e.g. mounting electrodes, current collectors or terminals in containers or encapsulations
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    • H01M8/0204—Non-porous and characterised by the material
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    • H01M8/2459—Comprising electrode layers with interposed electrolyte compartment with possible electrolyte supply or circulation
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    • H01M10/00—Secondary cells; Manufacture thereof
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    • H01M10/4214—Arrangements for moving electrodes or electrolyte
    • H—ELECTRICITY
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    • H01M8/249—Grouping of fuel cells, e.g. stacking of fuel cells comprising two or more groupings of fuel cells, e.g. modular assemblies
    • 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
    • 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
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells
    • 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

  • Halbert Fischel has been researching and developing efficient utilization of materials and processes using mechanical engineering, electrical
  • Case A "Electrochemical Cells Utilizing Taylor Vortex Flows", application Ser. No. 12/800, 658 of 20 May 2010, now U.S. Pat. No. 8,017,261 of 13 Sep. 2011.
  • Case A2 "Galvanic Electrochemical Cells Utilizing Taylor Vortex Flows", application Ser. No. 13/235,480 of 18 Sep. 2011, now U.S. Pat. No. 8,187,737 of 29 May 2012, which is a continuation-in-part of application Ser. No. 131194,049 (Case Al ), now U.S. Pat. No. 8,283,062.
  • Case D "Direct Reaction Fuel Cells Utilizing Taylor Vortex Flows", application Ser. No. 12/800,672 of 20 May 2010, now U.S. Pat. No. 7,972,747 of 5 Jul. 2011.
  • Case E "Dynamic Accelerated Reaction Batteries", application Ser. No. 12/800, 709 of 20 May 2010 with additional inventors Philip Michael Lubin and Daniel Timothy Lubin, now U.S. Pat. No. 7,964,301 of 21 Jun . 2011.
  • Electrochemical Cells Ser. No. 15/274,476 filed 23 Sep 2016, of which the present application is a continuation-in-part of U.S. patent 9,337,474 having U.S. Patent Application No. 14/717,139.
  • Case M "Electrochemical Cells With Convection," Ser. No. 62/286,994 filed January 26, 2016.
  • This invention relates to galvanic electrochemical cells that produce direct current electricity from stored energy in cells that employ mobile electrolyte. Rechargeable
  • electrolyte flow can move ions from one electrode to the other much faster than diffusion.
  • Such ion exchange between polar opposite electrodes is fundamental in electrochemical cells that produce direct current electricity from stored energy. That ion exchange rate limits electrical current.
  • Redox chemical reaction rate at the faradaic solid surface interface with electrolyte is another electrical current density limitation.
  • electrolyte convection greatly speeds both aspects of ion kinetics. It was used in Apollo Mission fuel cells and replaced by less efficient solid state and porous matrix electrolyte versions because multiple series connected mobile electrolyte cells yield high voltage but discharged through electrolyte circulation pathways.
  • U.S. Patent #8,911,893 B2 to Suppes provides an example of a packed bed electrode permeated by electrolyte providing unit cell voltage. Compression of the cell is applied to keep active particles and conducting additive (carbon black) immobilized and to somewhat improve electrical conduction. Volume energy storage capacity is not higher than common standard paste applications and there is no suitable provision for multiple cell series-connected electrolyte
  • each cell requires its own circulation pump or similar discharge through electrolyte circulation pathways will occur as described for Apollo Mission fuel cells. That was the principal reason for the historic move to fixed electrolyte.
  • Battery electrode/electrolyte architecture employs a 2-phase liquid/solid relationship between active solid faradaic (electronegative anodic and less electronegative or
  • Electrode current density controls time to recharge the stored energy on an electrode surface defined by the active faradaic mass per unit area of electrode. It is also understood that electrode current density is limited because electrode resistance produces a voltage decrement given by iR and i 2 R heating is a further serious issue.
  • One fundamental purpose of this invention is to show how to significantly reduce R and to do it without
  • electrolyte operates at the other end of the temperature scale and remains problematical as to size and cost. Both react at a triple-phase conductor/ion/gas boundary. Molten carbonate and many alkali electrolytes function effectively at intermediate temperature using inexpensive catalyst as effectively as noble metals. While electrode resistance remains an issue in all these examples, energy is stored in fuel and air so prior art has increased the ratio of electron conducting structure to catalyst mass in most cases. Specific electrode area resistance has reached 3 ⁇ 4 1 ⁇ 2 ⁇ -cm 2 with current density 3 ⁇ 4 3 ⁇ 4 to 1 ⁇ 2 A/cm 2 . Most fuel cell chemistry is based upon oxidizing 3 ⁇ 4 whether as such or extracted from hydrocarbon fuel. Consequently, 3 ⁇ 4 1 volt is all that can be produced.
  • 1 ⁇ 2 ohm times 1 ⁇ 2 amp is 3 ⁇ 4 volt or a 25% decrement in output voltage. It is also a 1/8 watt/cm 2 heat load or l/3 rd of the power for a cell delivering only 3/8 watt/cm 2 .
  • i 0 is increased in proportion to increased catalyst mass density and it follows that i is as well .
  • the desired purpose of the fuel cell is to be able to increase power density in proportion to fuel supply rate.
  • PEMFC ion selective electrode separating membrane e.g. (NationTM) having an order of magnitude more cation permeability in the plane of the membrane than through it where it is actually needed. It does more than prevent inter electrode convection. It also limits cell temperature to 60 °C . At higher operating temperature it tends to degrade more rapidly which accounts for the noble metal catalyst requirement. Eliminating a membrane entirely in favor of a freely permeable filter or nothing at all to impede inter electrode ion exchange convection will greatly enhance power density. More cost effective catalyst can operate at 300 or more °C with nearly the same or better activation as the noble metals. High temperature will also enable direct oxidation of most hydrocarbon fuels for better energy conversion efficiency than presently possible with low temperature fuel cells.
  • Electrodes commonly used in electrochemical cells e.g. battery and fuel cell, etc. cannot be used in this
  • a reasonable channel pathway flow cross-section area would have to be ⁇ 25 pm 2 in order to achieve at least 2 Darcy permeability for 1 centipoise (cp) electrolyte. Electrodes of this invention achieve ⁇ 20 Darcy permeability and electrical resistance ⁇ 10 ⁇ 3 ⁇ -cm 2 .
  • novel architecture is introduced to eliminate voltage loss in series connected mobile electrolyte cells due to reverse electro-motive force, emf imposed by electrolyte circulation pathways used in banks of prior art unit cells.
  • a unit cell is defined as comprising a single anode- cathode pair producing unit cell voltage which is generally too low to be useful, especially in high power applications.
  • Mobile electrolyte can greatly accelerate ion mobility and kinetics in secondary batteries for faster charge and discharge cycling but is rarely seen in prior art.
  • Mobile electrolyte is not used in capacitors because ions barely move away from the surfaces where they are created but is an essential feature, even in putatively solid state fuel cells to deliver oxygen and fuels and remove reaction products.
  • Mobile electrolyte is fundamental to the way flow batteries operate and water electrolysis relies on mobile electrolyte to add water and remove separated gases.
  • Circulation between electrolyte pools is by way of a single circulation loop across a gas break or other device separating inlet and outlet electrolyte.
  • the new feature is the inability of anodes at various electrode potentials, but insulated from one another or cathodes in the same condition to close an electrical or ion kinetic circuit that would otherwise allow them to discharge through their respective separate electrolyte pools .
  • Advantages of electrolyte convection in this invention include automatic internal cooling and heat balance for
  • electrochemical cell corrosion can be virtually eliminated by emptying the cell when not in use or drawing current. Also, this invention does not require separators, filters or expensive ion selective membranes to prevent short circuit between polar electrodes .
  • amp/cm 2 in electrochemical cells that produce direct current electricity from stored energy has been limited to very small electrode area specific current density commonly in the range of 0.01 amp/cm 2 (batteries) to 1 ⁇ 2 amp/cm 2 (fuel cells) . That is a consequence of high ohmic resistance between the active galvanic surfaces producing current by virtue of redox chemical reactions taking place on such surfaces and metal as the current
  • the inventor has reduced ohmic resistance to less than 1 milliohm-cm 2 which clearly translates into the possibility of very much higher current density and concomitant power in electrochemical cells. Therefore, the need and interest in electrolyte convection follows.
  • nanostructures comprising at least one of; carbon nanotubes (CNT) and graphene sheets (GS) having surfaces being at least one of; uncoated, permanently coated with and adjacent,
  • electrochemical redox active materials are one of; generic faradaic (battery) and catalytic (fuel cell) galvanic materials and used in this invention to comprise structures now identified and defined.
  • Porous galvanic 'membranes' comprise cohesive
  • galvanic material having an uncompressed thickness dimension defined as the average length of vectors normal to and extending from a membrane's first surface to where it intersects the membrane's opposed second surface.
  • the membrane thickness dimension is uniform, meaning it does not vary by more than 10%.
  • Cohesive shall mean the membrane possesses tensile strength not less than 0.1 MPa even though CNT and GS of which it is comprised has individual tensile strength greater than 60 GPa which is more than any other material known.
  • Freestanding cohesive galvanic membranes are often referred to as ' Buckypaper ' .
  • Such galvanic material attached to or deposited on metal surfaces when formed as layers thereon are also common as electrodes in the art.
  • galvanic material is not painted on metal surfaces as coatings or pastes containing conductive additives and binders, common in prior art. Rather, in one embodiment, a metal sheet has one surface covered with a
  • the prominences can be defined as metal finger-like projections and will be referred to hereinafter as spaced apart metal villi extending vertically outward from one surface of the metal sheet, Fig. 1. Any location not at a prominence cannot be further from a nearest prominence than three times the thickness dimension of the galvanic membrane. The sum of all villi
  • enclosing circle areas shall be less than 10% of the metal sheet area, with minimum circle diameter not less than defined
  • Villi height shall be not more than 10% greater than the membrane thickness dimension.
  • the side of the metal sheet bearing prominences shall compress a membrane against the plain surface of a second metal sheet but villi may not cut or penetrate the membrane. Sustained static compressive force shall be sufficient to cause the electrical resistance between the two metal sheets, as measured by a standard ohmmeter, to be less than 10 6 ⁇ -cm 2 ; essentially a short
  • the applied pressure required will normally be at least 7,000 kPa. It was shown in Fischel U.S. Patent 9,337,474 that such pressure and consequent contact resistance between membrane compression points and a metal surface produces a net functional electrical resistance between active galvanic material anywhere within the membrane and the metal of less than 10 ⁇ 3 ⁇ -cm 2 .
  • First and second metal sheets and galvanic membrane must have common area dimensions and at least two distinct edges to accommodate electrolyte flow entry and exit. Villi may not have sharp corners or edges so as to not cut or penetrate the membrane.
  • the described structure and pressure under which it functions defines the minimal basic electrode of this invention shown in cross-section in Figure 2.
  • the 3-layer sandwich can be repeated and stacked to further comprise an electrode of this invention. It is noted that electrolyte can enter an electrode at a metal sheet edge, flow within the electrode over the uncompressed portion of membrane surface and exit at a separate metal sheet edge.
  • both metal sheets have matching villi compressing the membrane from its opposite surfaces.
  • the villi of both sheets are aligned so the membrane is compressed between opposing villi.
  • Villi height is 3 ⁇ 410% greater than 1 ⁇ 2 membrane thickness whereby
  • a first metal sheet is blocked at an electrolyte entry edge and open at its corresponding electrolyte exit edge.
  • the second metal sheet is open at the same
  • electrolyte entry edge and blocked at the electrolyte exit edge It is a manifold rubric that forces electrolyte to flow through the membrane before it can exit the electrode. Compression causes functional electrode resistance of ⁇ 10 ⁇ 3 ⁇ -cm 2 when measured resistance between first and second sheet outer second surfaces is ⁇ 10 ⁇ 6 ⁇ -cm 2 .
  • a plain square weave metal wire screen covers and is adjacent the smooth first surface of metal sheet, Figure 5.
  • Wire crossover locations create localized prominences serving the same function as above described for metal sheet villi.
  • Plain wire weave defines a square pattern having window side length, here not more than 4.25 times membrane thickness, which assures the same compression criteria stated above whereby any
  • uncompressed location is no more than 3 times membrane thickness from a nearest compressed location.
  • Wire diameter is 3 ⁇ 45% greater than 1 ⁇ 2 membrane thickness when the screen compresses the
  • a second smooth metal sheet having a first surface covered by and adjacent the first surface of the galvanic membrane is used to sustain compression of the metal screen and membrane such that electrical resistance between compression sheets is ⁇ 10 ⁇ 6 ⁇ -cm 2 . Electrolyte enters the electrode at an edge and flows over the membrane uncompressed surface to exit at a separate edge.
  • a single membrane is compressed between two metal wire screens as hereinabove defined and necessarily positioned so that all windows of each screen align in vertical projection, referenced to a tangent plane externally adjacent all screen wire
  • Figures 2 and 3 or screen wire crossover locations, Figures 5 and 6 in brazing or solder so that hot compression will
  • Galvanic membrane material is stable to 1150 °C so melted solder/brazing will electrically join contact points without damaging the membrane. Solder/brazing also leaves a permanent physical connection at contact points whereby sustained
  • Figs. 7a & 7b illustrate sectional views of a stack of alternate wire screen and membrane.
  • the stack is secured under sustained or hot brazed compression. Section lines are shown in Fig. 4.
  • Fig.7 is Fig. 6 with many repeated membranes secured between vertically aligned metal wire screen windows.
  • Figure 8 illustrates how the Figure 7 stack side-ports are arranged to force electrolyte entering the stack from the left to flow through every membrane, to enter flow paths surrounding each membrane and leave the electrode on the right.
  • Screens are numbered n to n +1 from bottom. Even numbered left side entry ports remain open. Odd numbered on the left are blocked. Open exit ports on the right are odd numbered. Even numbered right- side ports remain blocked.
  • Selected screen edge closure forces normal vector permeation of electrolyte through active membrane layers secured by one of; closely spaced multipoint sustained compression and braze at facing screen crossover locations.
  • An electrode for an electrochemical cell comprising :
  • a first non-porous metal sheet having first and second
  • uniform wire mesh spacing is not greater than
  • a metal wire screen is adjacent at least the
  • the second surfaces of the non-porous sheets are subjected to a sustained compressive force of at least 7 million Pascal (7MPa3 ⁇ 4l,000 psi) and;
  • metal wire screens are collectively in
  • One of; sustained compressive force and brazing at wire screen crossover locations produces electrical resistance between first sheet and metal screen adjacent the second sheet of not greater than 1 ⁇ -ohm.
  • An electrode for an electrochemical cell wherein:
  • Area dimensions define at least first and second distinct edges and
  • Fig. 10 is the equivalent of Fig. 8 using 2-sided matching metal villiform screen one of which is shown in Fig. 9.
  • the galvanic membrane comprising at least one of; CNT, GS and mixtures thereof contain high concentrations of graphene molecular structure surface area.
  • the membrane volume fraction occupied by carbon surface structure depends on the application.
  • a 100 pm thick membrane can contain 800 cm 2 of active surface per cm 2 electrode area.
  • pseudosupercapacitors >30% volume provides >2,500 cm 2 in a 100 pm thick membrane.
  • the stack of galvanic membrane and metal wire screen shown in Figure 8 is a single composite electrode having extraordinary concentration of redox active mass and surface area connected to cell terminals with unprecedented low
  • the preferred embodiment for electrodes of this invention is according to Figure 8 using metal wire plain weave screen because it is readily available and very economical.
  • 55 pm wire in 60 mesh plain weave (inverse of wire spacing in inches) can use 100 pm thick membrane.
  • 177.5 pm (7.1 mil) wire works with a 350 pm thick membrane and 17 mesh.
  • the fraction of membrane area compressed and related wire volume is less than 5%. If flow channels occupy ⁇ 10% of electrode volume to ensure negligible flow restriction, about 85% remains for active galvanic membrane volume. That is an important metric in electrochemical cell design.
  • Electrolyte flow resistance for electrodes of this invention in accordance with Figure 8 is not more than that of a single membrane.
  • Figure 11 provides some examples. Resistance to flow over membranes is negligible but less important because it requires ion diffusion through the membrane which slows the electrochemical process. When electrolyte can flow intimately over every active particle, diffusion is a negligible factor in ion exchange kinetics. Diffusion time constant varies inversely with diffusion path length squared. For galvanic membranes suitable for use in this invention permeability is at least 2 Darcy and generally greater than 20 Darcy as proven by the data of Figure 11. [0049] Another transformative feature of this unique convection electrode architecture is the fact that effective convection takes place within an ultrathin extremely large area electrode.
  • porous convection electrodes are thick in order to hold a suitable mass of active galvanic material.
  • electrochemical process begins in a thin electrolyte entry zone and works its way toward the far end of the electrode whereby electrolyte must pass through a considerable length of spent material.
  • Fig. 8 architecture provides thin convection electrodes where their effective area is one layer area multiplied by the number of layers in the stack. It is superior to all examples in known prior art .
  • each layer is connected to cell terminals with ultralow ohmic resistance so their area specific current density can be more than two orders of magnitude greater than what is now possible with electrodes in any prior art application.
  • the effective electrode area is multiplied by the number of layers in the stack so net current level possible with the composite electrode and therefore power density becomes positively
  • a unit cell is one anode and one cathode paired and configured to allow electrolyte to flow as described above sequentially through both.
  • Anode is differentiated from cathode by the galvanic materials contained within their respective membranes.
  • Fig.12 shows one electrolyte recirculation loop through two composite electrode stacks. Flow direction is arbitrary and reversible.
  • the flow path contains a pump and electrolyte reservoir with gas dividing the flow path to prevent discharge by way of electrolysis in the flow loop caused by the potential difference between anode and cathode.
  • the composite electrodes could be spaced apart 4-sided stacks but are
  • An annulus has two edges; one each for electrolyte entry and exit as previously described hereinabove. Additional edges need to be sealed and merely add unnecessary complexity.
  • An inner annular composite electrode stack contains a central lumen suited to electrolyte access and outer cylindrical
  • An outer annular composite electrode stack defines a cylindrical inner surface spaced apart from the outer
  • composite electrode stack defines a cylindrical outer surface as one surface of a chamber fitted to collect electrolyte for circulation.
  • This unit cell electrode topology is not unique in electrochemical art although not much used in convection
  • the unit cell of Fig. 12 is capable of inordinate current at virtually negligible resistance delivered to its polar terminals.
  • the following invention discloses how high voltage can balance amperage for optimum practical power
  • Figure 13 depicts several unit cell stacks, each being as described for Fig. 12. They are separated by a plate
  • the separating plate also contains two insulating sections that prevent the cathode of the first
  • the sequence can be repeated in the same fashion for as many unit cells in a stack as needed to produce a desired voltage.
  • the end plates provide anode and cathode terminals and intermediate plates seal off electrolyte in the gap of one cell from mixing or even 'seeing' electrolyte in the gap of an adjacent cell. Isolation of electrolyte in the gap of each unit cell is essential to prevent discharge through electrolyte pathways. Note the inner lumen communicates only with anodes and the outer chamber communicates only with cathodes. That feature, additional electrolyte shielding as further described below and the unit cell separating plates comprise a novel invention for the following reasons.
  • Anodes and cathodes are arranged, respectively, to face separate anode and cathode pools of electrolyte and are 'screened' from those pools by actual fine weave metal screen or a metal wall penetrated by one of; one and a plurality of small holes; with either screen or wall being supported by dielectric insulation.
  • the holes or screen mesh is configured to cause at least 1 cm/sec convection
  • Flow channels are macroscale for electrode permeability of at least 20 Darcy when electrolyte flows over thin galvanic membranes. It is approximately 2 Darcy when electrolyte flows through thick galvanic membranes for better electrochemical efficiency, Fig. 11. Both require
  • centipoise viscosity at 1 cm/sec convection velocity In this invention, it is only necessary to use galvanic membranes much thinner than 1 cm and all in parallel rather than sequence. That is why electrolyte circulation can be very fast and current density higher than has ever been achieved in prior art.
  • electrical resistance is less than 10 ⁇ 3 ohm-cm 2
  • 10 amps/cm 2 can be produced in a fuel cell or 1 amp/cm 2 in a rechargeable battery.
  • Such combination of energy storage capacity and power density is positively transformational.
  • Prior art cell architecture creates grooves and depressions in pellicles and attached layers to accommodate material distortion and prevent peeling from a conductor in normal use; not
  • the remaining material is at least somewhat compressed by assembly in a spiral wound or plate structure.
  • Such structures can only compress an entire layer wherein it could not function for its intended purpose if compressed to substantially lower ohmic resistance.
  • An example of a concept that may appear similar but is radically different in accordance with this invention is shown in a micro
  • FIG. 17 It is a cohesive pellicle removed from an electrode and somewhat wrinkled upon drying but still showing distortions in its surface.
  • the grooved impressions are the result of pressing a square weave metal screen against the pellicle onto a metal current collector in an electrode.
  • the wire cross points apply enough pressure to virtually eliminate contact resistance at those locations whereas between those locations the pellicle needs little, if any, electrical contact with the metal. Between compression points it can come
  • stack compression serves a vital purpose beyond immobilizing galvanic materials.
  • Macro channels are low resistance fluid conduits that compress layers at a plurality of defined small areas separated by short distances which are a multiple of the thickness, e.g. 0.1 to 1 mm of a layer. >95% of the layer remains uncompressed and functions normally.
  • Net resistance between active galvanic surfaces and metal, referred to electrode area drops from about 1 ⁇ 2 ⁇ -cm 2 in fuel cells or 10 ⁇ -cm 2 in Li-ion batteries to an unprecedented level of less than 10 ⁇ 3 ⁇ -cm 2 when membrane layers are compressed against a metal conductor with pressure applied to defined small areas of 7,000 to 30,000 kPa depending on current density expected. More than 100 times the current density in batteries and 10 times in fuel cells becomes possible because the voltage loss for that current is only 0.01 volt in batteries. Prior art voltage loss at that current density would exceed the voltage produced in most cases; clearly impossible.
  • cathodes in batteries and fuel cells suffer from the slowest reaction rate and require the greatest weight and volume of active galvanic material, whether faradaic or catalytic. Improving cathode materials is the focus of much ongoing materials research but cathode function is more easily improved as here described. It is convenient to select the inner annular electrode as the anode because it requires less volume than the cathode and volume varies as radius squared for fixed axial length. The real benefit comes from choosing the direction of electrolyte flow from inner chamber, through the inner anode electrode, through the gap and into and through the outer cathode electrode. Electrolyte passing first through the anode acquires excess cation concentration which accelerates cathode reactions according to ordinary chemical reaction kinetics.
  • electrolyte residence time within the electrode will be determined by radial
  • Residence time in the anode can be increased to virtual completion of fuel oxidation independent of convection velocity. That is important because reaction gases and unconsumed fuel can poison the cathode oxygen reduction reaction, ORR catalyst. High temperature operation further discussed below will mitigate incomplete oxidation and CO production.
  • Convection velocity should be coordinated with available area concentration of faradaic material in the electrode for maximum power density.
  • Fuel cells of this invention operate without a fragile polymer semipermeable ion selective membrane or filter at elevated temperature.
  • 80% KOH can be used at 300 °C and 100 psi fuel and air/02 pressure with non-noble catalyst and only minor overvoltage.
  • Molten carbonate at 700 °C is flowable with 3.1 cp viscosity and can be used with Ni type catalyst CNT coatings having less overvoltage than Pt .
  • galvanic membranes used in this invention do not need or incorporate binders their temperature tolerance is 750 °C in air and 1150 °C otherwise. At these temperatures any hydrocarbon fuel is a candidate for direct fuel oxidation (sans 3 ⁇ 4 reformulation) in this invention.
  • Bockris [8] teaches that the catalyzed redox process occurs mainly and actually only
  • the highest concentration of gas/liquid menisci is foam. Such could not be sustained in a fuel electrolyte mixture without convection.
  • all useful hydrocarbon fuels are gas phase as, of course, is ( air.
  • Micro-foam producing spargers based upon venturi suction of gas into flowing liquid can produce stable flowable foam comprised of fuel gas and electrolyte.
  • the device can be connected to the fuel/electrolyte inlet but is otherwise separate from the cell.
  • foam flowing through permeable CNT membrane present an unprecedented interface of electrolyte menisci saturated with fuel covering nanoscale catalyst
  • Rapid redox reaction (Bagotsky) fills the foam with reaction gas and steam which proceeds to the gap where it crosses to the cathode. Interaction with catalyst surfaces through saturated menisci is well understood to be exceptionally efficient.
  • Oxygen containing gas is pumped into the foam through tubes placed within the gap as shown in Figure 14 and running the full axial length of all cells in the stack. Tubes are porous dielectric spargers made of ceramic frit or tubes with many small holes. They penetrate but are sealed to plates separating unit cells. Thus, electrolyte cannot communicate between cells. Other foam producing devices can be suitable for the stated purpose.
  • electrolyte exiting the cell is led through conduit tubing to an accumulator chamber containing gas.
  • the gas is for illustration purposes to show a physical break in the electrolyte path. The break interrupts what would otherwise be a closed electrolyte loop between electrodes for a unit cell but serves other
  • the gas volume absorbs volume changes within the battery for charge/discharge cycling, reconstituting electrolyte and holding it to drain the cell for storage.
  • the gas/liquid interface is a defoamer and reservoir for maintaining pressure and releasing exhaust.
  • One pump takes liquid electrolyte from the reservoir and returns it to the cell anode.
  • An entirely new benefit embodied by the electrode configuration of this invention as seen in FIG. 13, refers to a stack of a plurality (3 are shown) of unit cells connected in series to build high voltage.
  • the unit cells are separated by a dielectric spacer to insulate adjacent anodes from one another and adjacent cathodes from one another.
  • All inner and outer electrodes throughout a stack of repeated unit cells must be, respectively, either anodes or cathodes.
  • All outer electrodes must be of opposite polarity to the inner electrodes. Thus, center and outer electrolyte chambers respectively see one polarity .
  • Adjacent unit cell faces are electrically connected within separating plates as follows: A first unit cell in a stack of N unit cells is unit cell #1 with its inner electrode connected to a terminal for connecting to a load. Every
  • successive unit cell in the stack including the first, has its outer electrode electrically connected to the inner electrode of the next adjacent unit cell, i.e. outer of N to inner of N+l. It is important that the inner electrode of n is connected to the outer electrode of N-l but is NOT otherwise connected to any other electrode.
  • the outer electrode of N is connected to a terminal for connecting to the load. All electrodes are
  • the stack may be inverted with no other consequence than reversing the
  • a unique benefit of the above arrangement is an ability to isolate every electrode from electric field and ion kinetic communication with every other electrode except the one it faces to create battery potential and current.
  • Metal shields, insulated from any polarity allow electrolyte convection through electrodes and common electrode collection pools with
  • the conventional series connected convection electrode stack can be represented by a longitudinal arrangement of anode/cathode unit cells oriented with anodes connected to cathodes and for comparable convection, electrolyte chambers are fixed on opposite sides of the long axis of the stack.
  • Electrolyte enters anodes on one side of all cells collectively to leave from cathodes in similar fashion on the other side so circulation can be effected by a single pump. This is as closely analogous to the instant invention as may be possible. A defect is apparent in that each unit cell drives voltage in one
  • Embodiments of this invention comprise composite galvanic electrodes constructed by stacking layers with ultralow resistance connection to cell terminals through immobilized cohesive galvanic membranes comprising at least one of; nonwoven single-walled carbon nanotubes; nonwoven multi-walled carbon nanotubes; a single or plurality of layers of graphene sheets; one of; single-walled and multi-walled carbon nanotubes attached to one or both sides of metal sheet or woven carbon fiber; and combinations thereof; and wherein the nanoscale surfaces of these structures are one of; coated with galvanic material and adjacent galvanic particles lodged therein and immobilized.
  • Figures 18 and 19 are SEM photographs of cohesive CNT membranes respectively as formed without and with lodged and immobilized faradaic particles. It is on the nanoscale surfaces of CNT within membranes or the particles they entrain where galvanic current is produced. In this invention they are
  • FIG. 4 depicts a typical square weave metal screen or cloth.
  • the screen is used because it has a pattern of closely spaced small areas where its thickness is two incompressible wire diameters. Everywhere else its thickness is 0 or one wire diameter. Wire cross locations and windows can be stacked in alignment to provide an incompressible structure with macro channels for low resistance electrolyte flow in any direction. It comprises a low cost electrode with negligible ohmic
  • a convection battery and fuel cell require alternate layers of wire screen and galvanic membranes comprising internal nanoscale components, e.g. CNT, galvanic materials, etc. They are immobilized by compression between aligned wire crossover locations of a wire screen and together comprise one layer in the stack of layers comprising the composite electrode.
  • the 'galvanic membrane' must have thickness less than two wire diameters in order to leave channels for tangential electrolyte flow on both surfaces of the pellicle.
  • Ion mass transport kinetics is a combination of diffusion within an electrolyte permeable pellicle and convection over or through it. Electrical current is essentially instantaneous at low resistance but cannot exceed ion current. Diffusion time interval is
  • Galvanic membranes can be made with sufficient normal vector permeability to allow electrode layer entrance and exit port sequencing for electrolyte to take better advantage of that property.
  • a galvanic membrane placed between two screens can be subject to normal vector permeation merely by alternating clear and blocked screen edges. Channel entrances with respect to one edge of a screen are open but sealed on the electrodes opposite surface. Thus, when electrolyte enters the electrode through open channels on one surface it is forced to flow into screen channels that do not block its ability to leave at the electrodes opposite surface. Electrolyte must flow through the pellicle into a separate screen. It leaves the electrode from the surface opposite that at which it entered. Diffusion is much accelerated because pellicle internal pathways are very short.
  • Figure 1 shows a single-sided villiform metal plate used for a plurality of closely spaced point compression of galvanic membranes in accordance with the present invention.
  • Figure 2 shows a sectional view of metal villiform plate compression of one membrane to comprise an electrode for electrolyte flow over a galvanic membrane in accordance with the present invention.
  • Figure 3 shows a sectional view of metal villiform plate compression of one membrane between metal villi to
  • Figure 4 is a top plan view of a square-weave metal screen segment defining a plurality of overlapping wire areas to provide closely spaced multipoint compression of a galvanic membrane and showing sectional view reference lines.
  • Figure 5 shows a sectional view of metal sheet and metal wire screen compression of one membrane to comprise an electrode for electrolyte flow over a galvanic membrane in accordance with the present invention.
  • Figure 6 shows a sectional view of metal sheet and metal wire screen compression of one membrane lodged between screens to comprise an electrode for normal vector electrolyte flow through a galvanic membrane in accordance with the present invention .
  • Figure 7a shows sectional view A-A of metal sheet and metal wire screen compression of a stack of membranes and screens whereby each membrane is compressed between each screen, the stack comprising an electrode in accordance with the present invention .
  • Figure 7b shows sectional view B-B of metal sheet and metal wire screen compression of a stack of membranes and screens whereby each membrane is compressed between each screen, the stack comprising an electrode in accordance with the present invention .
  • Figure 8 shows a Fig. 7b sectional view extended and ported in accordance with Fig. 6 to comprise an electrode for normal vector electrolyte flow through all galvanic membranes in accordance with the present invention.
  • Figure 9 is a double-sided metal villiform compression screen with hexagonal windows.
  • Figure 10 shows a Fig. 8 style sectional view having square weave metal wire screens replaced by double-sided metal villiform compression screens to comprise an electrode ported for normal vector electrolyte flow through all galvanic
  • Figure 11 shows plots of normal vector permeation through several samples of galvanic pellicles as a function of pressure. Samples purchased and made by the inventor.
  • Figure 12 is a drawing of anode and cathode annular electrodes, mutually coaxial and spaced apart, with each
  • Electrode being as described in Fig. 8, to comprise a unit cell with electrolyte convection provided by a single pumped circulation loop in accordance with the present invention.
  • Figure 12a is a schematic illustration of the device of figure 12 in a system.
  • Figure 13 is a drawing of a stack of shielded anode and cathode annular electrodes in accordance with the present invention where each unit cell pair repeats Fig. 12 as series connected to the next through separating plates to accumulate voltage. Electrolyte convection is provided by a single pumped circulation loop.
  • Fig. 13a is an expanded view of a portion of the exemplary stack shown in Figure 13.
  • Figure 14 is a drawing of a stack of shielded anode and cathode annular electrodes in accordance with the present invention, repeating Figure 13 with added oxygen bearing gas sparger in the gap between electrodes. Electrolyte convection is provided by a single pumped circulation loop.
  • Figure 14a is a magnified section of sparger
  • Figure 15 is data to support the essence of the invention based upon the novel discovery that localized pressure in excess of 10 4 psi is required to reduce resistance through a galvanic membrane and into a metal current collector to less than 10 ⁇ 6 ohm.
  • Figure 16 is membrane bulk resistivity data in the plane of the sheet for configuring closely spaced multipoint compression to 10 ⁇ 6 ohm to achieve net membrane resistance less thanl0 ⁇ 3 ohm-cm 2 into a metal current collector.
  • Figure 17 is a microphotograph of the imprint made in a galvanic membrane by a square weave metal screen after the pellicle was removed from an electrode.
  • Figure 18 is an SEM photo image of a cohesive carbon nanotube membrane made by the inventor.
  • Figure 19 is an SEM image of a carbon nanotube
  • 'galvanic' means, 'of or relating to direct-current electricity, especially when produced chemically' . It will be used as a modifier, 'galvanic material' and is here referred to as material of description relevant to this disclosure having established galvanic properties.
  • 'Membrane' shall mean 'a thin sheet of natural or synthetic material' that is permeable to substances in solution.
  • 'Cohesive' implies tensile strength. It is a 'mat' if freestanding for normal handling.
  • 'Sheet' means, 'A broad mass or piece of material characterized as having area enclosable by a circle of defined diameter.
  • Membranes and sheets have a thickness dimension drawn normally from a first surface to an enclosing second surface that is less than l/10 th of the defined enclosing diameter dimension and varies by no more than 10% of a membranes natural uncompressed state.
  • an electrically conducting porous membrane may be referred to as a galvanic membrane and has first and second surfaces adjacent conducting surfaces.
  • the conducting surface is metal and is porous and permeable to electrolyte in this
  • Electrochemical cells of this invention use mobile electrolyte passing between negative anodes and positive
  • a primary component of this invention is the cohesive nonwoven CNT membrane mat material as structure containing one of; active faradaic and catalytic material either as strongly coupled coatings on CNT or as particles lodged and immobilized between nanotubes.
  • Figure 18 is an SEM photo of a CNT membrane made by the inventor and similar Figure 19 shows added
  • the density of a CNT Chiral fiber is 1.4 g/cm 3 . It has a lattice parameter of about 1.65 nm and there is little
  • Density of cohesive nonwoven CNT membrane varies from 0.2 to 0.5 g/cm 3 . Therefore, a volume fraction of CNT in electrodes of this invention is about 14% to 35%. That leaves 86% to 65% empty space for electrolyte and active battery material. Assuming 20% for electrolyte wetting of CNT surfaces, about 55% of membrane volume remains for active battery material mass. Catalyst uses less volume in a fuel cell.
  • Active cathode materials usually require more volume with faradaic material density of 4.1 g/ml and energy density in a Li-ion battery of 0.658 Wh/g. It will be shown that only 15% of membrane volume is needed in this invention for metal
  • the volumetric energy density is 1.26 kWh/L for the cathode in a convection battery. It is the energy storage driver since Li metal is substantially more compact especially as stored in Si coatings of anode CNT .
  • the combined polar electrodes yield an energy storage capacity of «1 kWh/L as a conservative but reasonable estimate. That exceeds industry standards because additional cooling volume is understood to not be required in ultralow resistance electrodes.
  • Electrically conducting galvanic material is at least an electrically conductive porous membrane (hereinafter referred to as an Active Membrane, (AM) . It comprises at least one of; cohesive nonwoven single- and multi-wall carbon nanotubes ( SW- and MWCNT), single and multiple layers of woven CNT, single and multiple layers of graphene, single and multiple layers of woven and cohesive nonwoven carbon fiber, single and multiple layers of woven and cohesive nonwoven T1O2 nanotubes or nanofiber and combinations thereof.
  • the tensile strength of cohesive nonwoven structures shall be at least 2 MPa so they can be handled as freestanding pliable membranes.
  • Tensile strength of graphene or CNT is greater than anything on the planet measured at 60 GPa.
  • Preferred CNT for AM comprise a mixture of lengths; 15% (MWCNT at 500 to 1, 000 pm) and the remainder SWCNT at 3 ⁇ 4100 ⁇ . Temperature tolerance of the materials is 750 °C in air and 1150 °C otherwise. They are inexpensive and commercially available.
  • catalyst fuel cell anode and cathode materials are in the form of particles having enclosing spherical diameter in the range of 1 ⁇ 2 to 10 pm. Prior to this invention they could not be
  • Particles are used in paste applications with binders in prior art.
  • a discovery of singular importance in this invention is the ability to stabilize these particles within the AM as a direct consequence of its novel method of attachment for low electrical resistance purposes.
  • Particles as well as CNT surface strongly coupled coatings can comprise 3 ⁇ 450% of galvanic membrane volume. Particles are uniformly distributed within the membrane's volume in the process of forming the membrane. In the case of nonwoven CNT they can be co-precipitated from
  • Important faradaic particles are spinels, multivalent
  • Mobile electrolytes are aprotic Li salts commonly used in Li-ion batteries and aqueous alkali otherwise. Batteries will benefit from antifreeze electrolyte for cold weather service, in particular, KOH at 31.5% or 7.34 molar with a eutectic at -65°C. It is superior to NaOH for this purpose. It is desirable to use maximum possible alkali concentration as ion convection defines electric current. At 40% or 10 molar there is still considerable freezing point depression but at 50% being 14 molar, KOH alkali becomes solid and only usable at higher temperature and
  • Fuel cell electrolyte interacts with catalyst surface and gas and operates at higher temperature and pressure to enable catalysts other than noble metals, e.g. Ni, NiO, MnO x or advanced and emerging versions appearing in the literature to carry out redox chemistry.
  • NASA 230°C, 75% KOH and 50 psi. 300°C, 80% KOH and 100 psi is used here to replace Pt and Ru with comparable activity and limited overvoltage.
  • the proposed convection cell embodiment architecture and materials are designed to withstand both pressure and temperature. Even molten carbonate at 700 °C is a suitable electrolyte comprising
  • Li2C03/ a2C03 at (48/52 mol/mol) ratio salt that provides Ni and NiO, respectively with faster HOR and ORR catalysis activity than any noble metal. Because CNT is easily plated with
  • nanoscale Electroless Ni and NiO it is a desirable substitute for porous LaMn03 in the cathode whereas the anode contains dispersed LiA102 and/or Li2Ti03 ceramic particles to stabilize the otherwise strongly coupled Ni .
  • Molten carbonate electrolyte flows at a viscosity of 3.1 cp .
  • Ultralow resistance electrodes begin as electrically conductive porous membranes (AM) and are freestanding components comprising a plurality of basic nanoscale graphene structures (e.g. sheets or tubes, CNT) as specified hereinabove. Carbon surfaces are one of; coated with strongly coupled galvanic material and combined with galvanic particles held within the membrane. In novel electrolyte convective electrodes of this invention both membrane first and second surfaces are adjacent a porous conducting surface. AM, or electrically conducting porous membrane and electrically conducting surface are building blocks of the present invention.
  • AM first and second surfaces are
  • This invention does not require separators, filters or expensive ion selective membranes to prevent short circuit or exchange of galvanic materials between polar electrodes.
  • Galvanic materials as strongly coupled sheet or CNT graphene coatings or lodged and immobilized galvanic particles within the electrodes of this invention cannot be dislodged as configured in accordance with patent 9,337,474.
  • This invention can use the most advanced or emerging nanoscale galvanic material for their associated high specific electrochemical activity in electrodes.
  • electrical conduction sink is defined as having virtually zero ohmic resistance to electrical conduction.
  • they comprise a plurality of proximally spaced apart discrete areas wherein the full thickness of the galvanic membrane material is one of; compressed against and brazed onto the metal surface. Compression or brazing should not sever high tensile strength fibers or graphene layers comprising the sink. Those should lead unaltered into and become contained within the sink. Touching, i.e. ordinary contact with the sink by severed graphene merely creates the same electrical
  • Patterns considered will be a hexagonal, square and 60° triangle pattern of a plurality of circular compression areas and a pattern of contiguous square ribs. All will have less than 10% compressed area.
  • the following shows that any pattern of a plurality of spaced apart noncontiguous compression areas is preferred over contiguous or discrete line segments. Nevertheless, the invention is not limited to a particular pattern so long as the novel criteria are met .
  • rib width must be ⁇ 0.05D or ⁇ 0.3t to satisfy the same 10% criterion. That is more difficult because compressors that are too narrow may cut into the membrane. That must be avoided in this invention, so contiguous line segments are not preferred.
  • the pattern is intended to shorten the distance electricity must travel within the membrane to reach a
  • Gaberscek and Ma used galvanic paste on metal backing to explore applying pressure to the electrode to improve its discharge power. Pressure applied to total electrode area for a period of time was relaxed for one hour to recover electrolyte permeation and electrical viability which did improve somewhat compared to uncompressed samples. But maintaining effective pressure over the entire electrode for continuous use is clearly not suitable. By limiting compressed area to less than 10% for an entirely different purpose, namely, electrical connection the remaining 90+% need not be sacrificed.
  • Figure 1 illustrates a one-sided villiform metal compression plate 10 having fingerlike extensions 12 of a first surface 14, villi with distribution pattern, number, diameter, spacing and height in accordance with the specification of this invention.
  • FIG. 2 illustrates one electrode 16, comprising one of an anode or cathode 18, of a convection battery or fuel cell.
  • the villi 12 of the one-sided villiform metal compression plate 10, adjacent a second surface of AM (active galvanic membrane) 22 adhere a first surface of AM 24 by one of; sustained
  • Sustained compression or hot compression for brazing shall be not less than 7,000 kPa.
  • Electrical resistance as measured by an ohmmeter shall be less than 10 ⁇ 6 ⁇ -cm 2 between villiform 12 and smooth metal plate (s) 30.
  • the edges of the three-layer sandwich are configured by extension 32 of the smooth metal plate 30 to provide entrance 34 and exit 36 ports to enable electrolyte flow 38 over the second surface 22 of the AM wherein villi 12 are approximately 10% taller than the defined AM thickness.
  • Villi tips are tinned with brazing or solder and the sandwich is heated under pressure to form the permanent joint, cooled and then pressure withdrawn.
  • the term tinning and tinned is used throughout in the broad sense of coating to prepare a surface for soldering or brazing to form a metal joint but does not imply using Sn. Other metals or alloys are used for low and high temperature applications.
  • FIG. 3 illustrates one electrode 40, comprising one of; anode and cathode, of a convection battery or fuel cell.
  • the villi 12 of a first one-sided villiform metal compression plate 42 are adjacent the second surface of AM 22 and villi 12 of a second one-sided villiform metal compression plate 44, are adjacent the first surface of the AM 24.
  • Villi 12 of first and second compression plates 42, 44 are in registered opposition so as to compress the one AM 46 between every pair of opposed villi 12.
  • the first compression plate 42 is open at a first edge first edge 48 to provide electrolyte entrance 34 at port but extended to block electrolyte exit at an opposed second edge 50.
  • the second compression plate 44 is extended to prevent electrolyte entrance at the said first edge 48 but open via exit port 36 at the second edge 50 to electrolyte exit. All villi 12 are of substantially equal height which is approximately 10% greater than 1 ⁇ 2 defined membrane thickness dimension. 52 indicates entering electrolyte flow space, 54 indicates exiting
  • electrolyte flow space and arrows 56 show how electrolyte convectively permeates the AM.
  • Plates 42 and 44 are one of; held under sustained compression and durably joined by one of;
  • brazing and solder at joints 26 are brazing and solder at joints 26. Either process is hereafter referred to as joining.
  • compression for joining shall be not less than 7,000 kPa.
  • Electrical resistance must be ⁇ 10 ⁇ 6 ⁇ -cm 2 between metal plates.
  • FIG. 4 shows a plain square weave metal wire (SWMW) screen fragment 58. It is 2 wire diameters thick at wire
  • the screen defines first and second sides by planes tangent externally to wire crossover locations and screen thickness is defined by the length dimension of a normal vector between said first and second sides.
  • wire crossover locations 60 are analogous to the villi of a 2-sided villiform metal plate with open windows 62 created by wires 64 and 66 connecting simulated villi.
  • Horizontal wires 68 and vertical wires 64 in Fig. 4 define a pattern of square sides having dimension ⁇ 4.25 times AM thickness as required by this invention specification. It is understood that commercially available metal wire screen is very much cheaper than villiform metal plate or screen and is used here in place of villiform material as now explained.
  • FIG. 5 illustrates an exemplary embodiment having one electrode 70, comprising one of; anode and cathode, of a convection battery or fuel cell.
  • a first metal plate 72 first surface is covered by a first side of an adjacent SWMW screen 74 shown as section view B-B of Fig. 4. Wire crossovers of the SWMW screen, hidden in the Fig. 5 view, compress less than 10% of the AM 76 second surface adjacent the second side of the screen toward a first surface of a second metal plate 78 adjacent the first surface of the AM.
  • Both edges of the second metal plate are extended to contain the AM but not so far as to close electrolyte inlet 80 and outlet 82 ports located, respectively, at first and second edges of the 4-layer assembly.
  • Sustained or hot compression for joining shall be not less than 7,000 kPa so that measured electrical resistance is ⁇ 10 ⁇ 6 ⁇ -cm 2 between metal plates.
  • Assembly ports are configured to enable electrolyte flow over the AM second surface when the defined thickness dimension of SWMW screen is approximately 10% greater than the defined AM thickness. If SWMW screen crossover points are tinned the sandwich can be heated under pressure for joining, cooled and then pressure withdrawn.
  • Figure 6 illustrates another exemplary embodiment one electrode 84, comprising one of; anode and cathode, of a convection battery or fuel cell. It relates to the concept of Fig. 3 wherein one AM 86 is compressed between two SWMW screens provided screen windows are in aligned registry.
  • An incentive for this version of the same concept comes from the inherent economy of commercial metal screen material. They are available or can be easily woven with wire made of many metals with high precision. Stainless steel, SS is most common.
  • FIG 6 exemplary embodiment uses Figure 4 screen section A-A to describe the assembly.
  • Wires 64 and 66 comprise crossover locations 88 and define planes tangent to first and second sides of first 90 and second 92 screens.
  • Screen first sides are respectively adjacent first surfaces of first 94 and second 96 metal compression plates.
  • First and second screen second sides are respectively adjacent opposite surfaces of one AM 86.
  • First and second screen windows 62 are in registered alignment so as to compress one AM between opposed wire
  • the first compression plate 94 is open at a first edge 102 to provide electrolyte entrance at port 104 but extended to block electrolyte exit at an opposed second edge 106.
  • the second compression plate 96 is extended to prevent electrolyte entrance at the first edge 102 but open via port 104 at the second edge 106 to electrolyte exit 108.
  • Wire diameters are substantially equal and approximately 10% greater than l/4 th defined membrane thickness dimension in this embodiment.
  • 110 is entering electrolyte flow
  • 112 indicates exiting electrolyte flow
  • arrows 114 show how electrolyte convectively permeates the AM 86.
  • Metal compression plates 94, 96 are one of; held under sustained compression and durably joined at joints 116. Sustained compression and hot compression for joining shall be not less than 7,000 kPa. Electrical resistance must be ⁇ 10 ⁇ 6 ⁇ - cm 2 between metal plates.
  • Figures 7a and 7b show another exemplary embodiment to employ the Fig. 6 concept as a repeated pattern.
  • AM 118 and SWMW screen 120 alternate as layers in a stack 122 under collective compression between first surfaces of first 124 and second 126 plates or joined as further explained.
  • Fig. 7a is an A-A
  • each compression plate comprised of wires 66 and 68 and permanent joints 116. Screens adjacent first surfaces of each compression plate do not
  • Electrolyte flow between and over every AM in the stack from entrance on the left 110 to exit on the right 108 is shown by arrows in Fig. 7b. Every AM is compressed between screens by crossing wires for approximately one half of defined AM thickness from both first and second AM surfaces. Wire dimeters and spacing are equal to within ⁇ lpm and are 3 ⁇ 410% greater than half the defined AM thickness. Windows and crossover points must match in alignment to within ⁇ 2% of wire diameter or compression will collapse the stack. It is imperative that collapse is avoided for purposes of this invention in order that one of;
  • FIG. 8 shows another exemplary embodiment of a preferred electrode 132, comprising one of; anode and cathode, of a convection battery or fuel cell. It employs the concept of Figs. 7a and 7b essentially for repeated AM and screen layers to build energy capacity.
  • Side-ports for convective electrolyte entry 134 and exit 136 exist at alternating screen edges not blocked in a stack by filler 138 comprising dielectric or metal material impregnating and blocking screen windows nearest said screen edges for a distance equal to at least one screen window.
  • This method of manifolding electrolyte flow balances convection velocity among the several open ports and is used for reasons having to do with connecting multiple cells in series for high voltage as further explained.
  • Entry and exit pots are configured for electrolyte permeation through rather than over AM to promote faster redox chemistry, virtually nullify diffusion and to speed ion kinetics.
  • Stacks comprise n AM layers 140
  • AM first surfaces face and are spaced apart from nearest AM second surfaces by a narrow gap 142 containing the mid-plane between screen thickest point tangent planes.
  • Entry and exit ports line up with screen midplane 142 and gap 140 between AM layers.
  • An electrolyte entry port at a screen edge must be closed at its opposite edge in the same plane. That rule forces electrolyte entering a screen layer at its defined midplane to flow through the two AM layers adjacent the said gap as shown by arrows 144 in Figure 8.
  • n-even electrolyte entry from the n/2 open port side is illustrated in Fig. 8. If all ports on both sides are open, flow through the electrode is symmetrical for all n but electrolyte can only flow over AM. Diffusion within AM becomes a limiting factor.
  • the method of screen edge blocking and selected open ports has an important function when convection electrodes are stacked in series connection for high voltage.
  • Figure 9 is an example of a 2-sided metal villiform compressor 146 in a pattern of villi 148 with three times tAM (AM thickness)
  • Figure 10 is another exemplary electrode 154, comprising one of; anode and cathode, of a convection battery or fuel cell functionally if not structurally identical to Fig. 8.
  • AM 156 layers alternate with hexagonal 2-sided villiform metal screen layers 158, substituting for and taking the place of square weave metal wire screens shown in Fig. 8.
  • Side-ports 160 and 162 are provided as openings in side- walls 164 and 166 configured for electrolyte permeation through, rather than over, AM.
  • Stacks comprise n AM layers alternating with (n+1) screens.
  • AM first surfaces 168 face and are spaced apart from nearest AM second surfaces 170 by a narrow gap 172 containing a midplane 174 and struts 176 connecting opposed villi.
  • Electrolyte entry ports line up with screen midplane 174 and gap 172 between AM layers.
  • An electrolyte entry port 160 on one side must be closed on the opposite side 178 in the same plane.
  • Electrolyte entering through a port at a screen layer midplane on one side of the stack will be forced to flow through the two AM layers 156 adjacent the gap 172 as shown by arrows 180 in Figure 10.
  • Villi 182 of one screen compress AM 156 material against the villi 184 of an adjacent villiform screen 158.
  • Permanent joints 186 are due to hot compression of the stack in a vacuum oven using at least one of; soft solder and medium solder and hard brazing alloy at a suitable temperature for each method.
  • the tips of the villi 184, 186 are first 'tinned' with the appropriate material well known in the brazing art.
  • Ag-Cu, Ag-Zn, Cu-P, Ag-Cu-P and even Au-Ag or Au-Cu are useful alloys for high temperature applications and corrosion resistance.
  • Vacuum brazing is normally carried out without flux application. Because so little material is applied to villi tips or metal wire crossover locations noble metal brazing does not add significant cost to the assembly but does provide corrosion resistance and high temperature operation of the electrode.
  • Figure 11 explains some reasons for the electrolyte convection provisions peculiar to this invention. Permeation of packed galvanic particle beds (Gordon) presents unacceptable prior art electrolyte flow resistance especially when packed with sufficient compression to improve poor electrical
  • Fig. 11 presents electrolyte permeation resistance for a sample of purchased and inventor made CNT membranes and AM having various porosities and containing different particle weights. It is easily seen that a stack of more than a few membranes would offer considerable flow resistance; which can be tailored for a preferred single membrane if flow is required through only one membrane at a time.
  • Prior art packed bed permeability of less than 1 Darcy can be improved to greater than 20 Darcy in convection electrodes of the instant invention.
  • resistance to 1 centipoise (cp) flow at 1 cm/sec through 1 cm 3 volume of the electrode of Fig. 8 is less than 1 psi. Ultralow electrical resistance is unaffected because that is due to closely spaced distributed multipoint compression. For the first time permeation and electrical resistance become independent variables, whereas the prior art must trade one off against the other.
  • Stacks are assembled with AM containing one of; anode and cathode galvanic material comprising one electrode of a unit cell battery or fuel cell.
  • the screen crossover locations are 'tinned' for low, (battery), ⁇ 100 °C, medium, (fuel cell), 3 ⁇ 4300 °C and high, (molten carbonate), 3 ⁇ 4700 °C temperature applications.
  • 'Soft' solder will do for battery screens.
  • 'Hard' solders are suitable for medium temperature and brazing alloys are suited for high temperature joining.
  • Tinning can be a hot roller or platen process coating only screen 'high' points. Selected screen edges are filled with tinning material.
  • the assembly is placed in a vacuum oven and heated to appropriate temperature for melting the joint. The assembly is under pressure for a hot cycle and after cooling it can be handled without further compression.
  • CNT and galvanic materials in common use are impervious to joining temperatures.
  • Electrodes herein described are suitable for use in a variety of electrochemical cells, including fuel cells, electrolysis cells, galvanic batteries, including
  • FIG 12 and figure 12a (basic core) which illustrate a stack, unit cell battery or fuel cell 200 with two convection electrodes, each as hereinabove described. Both are configured for convenience of the drawings and actual use as nested concentric annular anode 202 and cathode 204 electrodes.
  • An annulus 206 possesses the required two edges for preferred electrolyte entry through open ports at anode edge 208 followed by exit through open ports at opposite edge 210; in turn, followed by entry through open ports at cathode edge 212 and finally followed by exit through open ports at opposite edge 214.
  • the perimeter of cathode outer edge i.e. surface can be square or rectangular for cell packaging convenience without affecting the description that follows.
  • An anode inner lumen 216 is enclosed by the anode inner surface 208 and all anode entry ports.
  • a cathode outer surface 214 comprising all cathode exit ports 218 cooperatively forms an electrolyte collection chamber 220 with an enclosing wall 222.
  • the inner radius of the anode creates a lumen 216 used to contain entering electrolyte (feed flow) 224 covering the anode inner surface 208.
  • a cathode outer chamber 220 covers the cathode outer surface 214 and is used to contain exiting electrolyte 226.
  • the anode outer radius 228 is less than the inner radius 230 of the cathode to form a gap 232 separating spaced apart facing cylindrical surfaces comprised of the outer surface 210 of the anode and inner surface 212 of the cathode.
  • Fig. 12 is a unit cell of a single battery 200.
  • the basic principles and claims of the invention are not altered if either electrolyte flow direction or positions of anode and cathode, i.e. labels and polarity are reversed.
  • Electrolyte 238 is delivered to the central lumen 216 of the annular anode structure.
  • a pump 240 and accumulator 242 containing gas is required in the electrolyte circulation loop 246.
  • the main purpose of a gas accumulator 242 is to absorb AM volume changes in battery cores due to charge/discharge cycling and product gas from fuel cells. It allows continuous
  • Circulation 248 is generally into and through the anode 202 followed by circulation through the cathode 204 to maximize cathode redox chemical activity. Gas in the accumulator breaks the self-discharge electrolyte pathway in a unit-cell 200.
  • Dielectric insulation plates 250 partially enclose the axial ends of the anode 202 and cathode 204.
  • a dielectric plug 252 is insertable in the end of the lumen 216 to cap the lumen 216.
  • a metal terminal 254 is electrically connected to the anode 202 at an end of the unit cell 200.
  • a metal terminal 256 is
  • the metal terminals 254, 256 can conduct electricity from the unit cell 200 to another unit cell 200 or as part of an electrical circuit.
  • inner chambers enclose, isolate and separate multiple common polarity electrode surfaces arranged in a stack for series connection and high voltage as shown in Figures 13 and magnified section 13a.
  • the stack comprises repeated versions of Figs. 12 separated by a conductive metal plate 350 containing metal connecting the lower anode to the next upper cathode and dielectric insulation 352 that insulates all cathodes from one another and all anodes from one another. All anodes remain inner annular electrodes so all cathodes are outer annular electrodes.
  • the arrangement permits a single electrolyte circulation loop serving all electrodes and unit cells in the stack. It is a major simplification of a classic problem not solved in prior art.
  • Fig. 13 shows one of; a single and plurality of small holes in the wall separating inner chambers from outer chambers.
  • Figure 13a is a magnified view of a segment of the anode central lumen for clarity. Electrolyte passing between inner and outer chambers must do so through and within these holes at convective velocity greater than 1 cm/sec. This feature has no purpose for a single unit cell shown in Fig. 12 but is of vital importance to connecting multiple unit cells in series for high voltage as hereinafter further explained.
  • the circulation loop in Fig. 13 moves electrolyte from outer cathode chamber to anode lumen.
  • a facility for one pump and circulation loop connecting multiple battery/fuel-cell unit cells in series for high voltage is novel in this invention.
  • the connection profile is not unique except for how convection is enabled.
  • Prior art alkali fuel cells are more efficient than acid and use non-noble metal catalyst at 250 degrees C to 300 degrees C which also dissolves carbonates to keep precipitate from clogging electrodes in some popular fuel cells.
  • Common design uses a more open matrix that allows electrolyte flow between electrodes (parallel to the electrodes) or through the electrodes in a transverse direction to collect reaction
  • Figure 13 illustrates stacking unit cells connected for increasing voltage of the composite cell 300. It
  • Inner electrode chambers 306 and 308 are adjacent and fully enclose, respectively the inner anode and outer cathode surfaces where electrolyte either enters or exits electrodes as shown in Fig. 8. Electrolyte covering these respective electrode surfaces is fully isolated and shielded by metal walls 310 that comprise the respective inner chambers.
  • the metal walls 310 are insulated from electrodes by a dielectric plug 312 and dielectric supports 314. No anode can 'see' another anode through an electrolyte pathway except through small holes in inner chamber walls. The same is true for
  • anode 324 and cathode 326 Flow between anode 324 and cathode 326 is entirely reversible for batteries and there may be a benefit for doing it for certain paired redox faradaics undergoing charge/discharge cycling.
  • the focus is on a single flow path from anode through cathode and back to anode.
  • One flow path is easier to control as compared to the several flow paths required in prior art mobile electrolyte fuel cells.
  • Fuel preferably in gaseous form at high (300 °C) temperature and (100 psi) pressure is mixed with alkali (e.g. 80% KOH) preferably to produce a foam mixture in any of a number of methods known in the art.
  • alkali e.g. 80% KOH
  • Fuel saturated menisci will react favorably and quickly on catalyst surfaces within the anode to produce a surfeit concentration of cations somewhat diluted by additional water. These will be K + given the preferred choice of alkali electrolyte. In prior art fuel cells K + is ineligible to pass through an electrode
  • ORR Cathode oxygen reduction chemistry
  • ORR is normally much slower than fuel oxidation in prior art.
  • excess cation concentration in the electrolyte covering ORR catalyst surfaces promotes 0 ⁇ adsorption on catalyst surfaces in keeping with accepted chemical reaction kinetics.
  • DOFC Direct Oxidation Fuel Cells
  • FIG. 14 shows dielectric (e.g. glass or ceramic) tubes 330 bearing oxygen passing through a sealed hole 332 in the plate.
  • Fig 14a is a magnified section of the gap 232 and metal unit-cell separator plate (metal terminal) 350. Pure O2 or O2 in gas under pressure fills the tube which comprises a gas sparger within the gap.
  • the walls of the tube either contain holes communicating between gas and electrolyte surrounding the tube or the tube walls comprise a porous dielectric frit that passes gas under pressure through the walls of the tube. Gas passing into
  • electrolyte within the gap will create a foam-like mixture of O2 bearing gas, residual fuel and product gas from the anode and electrolyte under convective pressure to enter the cathode. Any residual fuel mixed with O2 gas will be quickly oxidized under pressure at 300 °C . Because the tubes passing between unit-cells contain only gas and are dielectric, short circuit through electrolyte is not possible.
  • the galvanic membrane, AM (20, 46, 76, 86, 156) shown in FIGS. 2 - 3, 5-8 and 10 may include at least one of; a cohesive mat 340 of nonwoven single-walled carbon nanotubes, Figure 18; a cohesive mat 340 of nonwoven multi-walled carbon nanotubes; a plurality of layers of graphene sheets (not shown); single and multi-walled carbon nanotubes grown on woven carbon fiber 342 and combinations thereof being one of; coated with nanoscale active galvanic material and containing lodged and immobilized nanoscale active galvanic particles, Figure 19.
  • Figure 16 is a chart of bulk resistivity, ohm-m in the plane of sample galvanic membranes made in house and purchased commercially. Experimentally measured data is essential to a calculation of net electrode resistance using material in accordance with the invention. It cannot be inferred from known conductivity data respecting components, e.g. CNT or graphene that comprise the membrane due to complexity of composite structures .
  • Figure 16 shows that not to be a valid premise.
  • lateral bulk resistance within the membrane is 3 ⁇ 410 ⁇ 2 ohm-cm as shown in Figure 16 to report actual experimental data.
  • the reason for 4 orders of magnitude higher resistance is the accumulation of imperfections in graphene structure over
  • the material is commercially available and will assure that a point furthest from its nearest compression is electrically connected to an electrical sink as now further described .
  • a continuous uninterrupted graphene electrical conduction path is established from a farthest point of active galvanic chemistry to a conduction sink in low resistance contact with the metal. It is understood that CNT is graphene rolled into a tube.
  • Figure 15 provides resistance data measured between the outer surface of sample galvanic membranes and the metal support surface normalized to electrode area as a function of pressure. Copper probes of various sizes were used with a sensitive ohmmeter and the membrane compressed over a large range of pressure. 1 psi, is the approximate pressure normally applied to the entire membrane or paste in a prior art assembly Resistance is consistently about 1 ⁇ 2 to 3 ⁇ 4 ohm-cm 2 . At 7,000
  • an ohmmeter with probes is used to measure resistance at any point within any one of the plurality of local conduction sinks distributed on the membrane area, the compressed areas comprising a collective area that subtracts less than 10% from the membrane's electrochemically active area.
  • Figure 17 is a microphotograph of a membrane removed from an electrode bearing a 100 mesh plain metal screen imprint. There was no penetration or cutting of the membrane upon
  • a significant difference is due to the absence of a separating membrane in the AM convection electrode while prior art batteries contain at least one 50pm membrane in an electrode having a 50 to lOOpm active coating. That can cut energy storage density by l/3 rd to 1 ⁇ 2 compared to AM electrodes of this invention.
  • FIG. 17 microphotograph of a membrane portion removed from an electrode after being compressed by SS screen reveals an intact membrane suffering no penetrations or cutting. Wrinkling of the uncompressed portions occurs upon removal from the electrode metal backing as the membrane dries.
  • the wire cross points apply enough pressure to virtually eliminate contact resistance at those locations whereas between those locations the pellicle has and needs little, if any, electrical contact with the metal. Between compression points it can come completely off the metal backing but it remains uncompressed and electrochemically active. It has room (volume) to expand and contract with greatity. Yet, resistance between pellicle as a whole and supporting metal remains more than three orders of magnitude lower than conventional assemblies because distance between compression points is short and material bulk resistance is low.
  • the imprint was made by the square weave metal screen in a galvanic pellicle which was removed from an electrode.
  • Figure 18 is a SEM photo of a nonwoven CNT membrane and Figure 19 is such a membrane showing typical galvanic
  • FIG. 11 is an AM ( galvanically active membrane) permeability data used in part to test particle stability reported for samples such as depicted in Figure 19. Samples were tested both as laid upon porous metal backing with negligible applied pressure and secured as required by this invention
  • porous galvanic active membranes of this invention can contain and immobilize particles having enclosing spherical diameter dimension of 0.5 to 10 pm in addition to strongly coupled coatings on graphene surfaces to serve as stable
  • An important additional feature of the disclosed electrodes is temperature tolerance for use in fuel cells due to the previously mentioned absence of a separating permeable dielectric membrane or adhesive pastes.
  • the disclosed electrodes are the only electrodes that fully and permanently lodge and immobilize all galvanic
  • the invention provides a better way to reduce
  • the invention provides high capacitance and series voltage design freedom to achieve a substantial increase in both energy and power density.
  • Fuel cell electrodes in this invention will benefit from a combination of energy and power density improvements due to negligible ohmic resistance, the absence of an ion selective semipermeable membrane and electrolyte convection newly possible in combination with compact high voltage.
  • the essential elements and principles of the invention can be summarized as follows: They define an electrode for electrochemical cells; the electrode comprising an electrically conductive porous surface and an electrically conductive porous membrane having a first surface and an opposed outer second surface separated from the first surface by a thickness
  • Mobile electrolyte is configured to prevent discharge or parasitic electrical currents in series connected unit cells for high voltage configuration. In prior art such currents are due to ion kinetic pathways in electrolyte circulation provided by a single pump and circulation loop.
  • a galvanic membrane is defined herein as comprising at least one of; a cohesive carbonaceous mat comprising nanoscale carbon surfaces of at least one of; SWCNT, MWCNT and graphene layers; nanoscale carbon surfaces coated with electrochemically active galvanic material; electrochemically active galvanic particles lodged within the mat; and a solid or porous metal sheet coated on both surfaces by attachment deposition with a layer comprising at least one of; SWCNT, MWCNT and graphene layers.
  • the word "about” is to mean plus or minus ten percent .
  • Cohesive shall mean having tensile strength of at least 2 MPa.

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Abstract

L'invention concerne une électrode comprenant des membranes galvaniques ayant une épaisseur définie par une longueur moyenne de vecteurs normaux à une première surface de membrane et s'étendant jusqu'à ce que lesdits vecteurs croisent une seconde surface de membrane non comprimée; une feuille métallique non poreuse ayant des première et seconde surfaces; une feuille diélectrique non poreuse ayant des première et seconde surfaces; des écrans de fil métallique à armure carrée ayant un diamètre de fil légèrement supérieur à une moitié de l'au moins une dimension d'épaisseur de membrane galvanique; au moins une membrane galvanique étant adjacente à l'écran de fil métallique sur l'au moins une première et seconde surfaces de membrane galvanique dans un empilement de membranes et d'écrans; l'écran de fil métallique est adjacent à la première surface de la feuille diélectrique non poreuse; les secondes surfaces de feuilles métalliques non poreuses ont une pression constante d'au moins 7 millions de Pascal; et l'écran de fil métallique est collectivement en alignement vertical incompressible avec un autre écran de fil métallique.
PCT/US2017/066558 2017-01-18 2017-12-15 Cellules électrochimiques à électrolyte mobile WO2018136176A1 (fr)

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