flow battery

Abstract

The flow battery of the present invention includes a first conductive plate and a second conductive plate, each of which has a corrugated surface with a first plurality of corrugations extending along a first axis of the conductive plate and a second plurality of corrugations extending along a second perpendicular axis of the conductive plate, arranged to form a first cell of the flow battery, the corrugated surfaces of the first conductive plate and the second conductive plate providing a cathode and a corresponding anode of the first cell and defining opposing side walls of an electrolyte flow path between the first conductive plate and the second conductive plate.

Description

[Technical Field]

[0001] The present disclosure relates to batteries. More particularly, but not exclusively, the present disclosure relates to flow batteries. [Background technology]

[0002] In flow batteries, such as those disclosed in U.S. Patent Publication No. 2013 / 0037760, charged anolyte and catholyte are supplied to the cells of a battery in use, and depleted anolyte and catholyte are removed from the cells. This configuration offers the advantage that flow batteries can be conveniently "recharged" by replacing depleted electrolyte with charged electrolyte. An additional advantage of flow batteries is that the electrolytes are generally non-volatile, resulting in long-lasting cells. While such batteries are suitable for a variety of applications requiring power storage, they may be particularly advantageous for use in electric vehicles, where, for example, replacing depleted electrolyte may be faster than charging a conventional electric vehicle battery. However, flow batteries may have a relatively large mass and a relatively low energy density compared to other batteries traditionally used in electric vehicles.

[0003] The present disclosure aims to alleviate the above problems, and further aims to provide an improved flow battery and an improved electric vehicle. Summary of the Invention [Means for solving the problem]

[0004] According to a first aspect, a flow battery is provided that includes a first conductive plate and a second conductive plate, each of which includes a corrugated surface formed by a first plurality of corrugations extending along a first axis of the conductive plate and a second plurality of corrugations extending along a non-parallel second axis of the conductive plate, and the first and second conductive plates are arranged to form a first cell of the flow battery, in which the respective corrugated surfaces of the first and second conductive plates provide a cathode and a corresponding anode of the first cell and define opposing walls of an electrolyte flow path between the first and second conductive plates.

[0005] The corrugated shape along two different axes increases the contact area between the plates and the electrolyte relative to the plate footprint, allowing for more efficient design of batteries in embodiments. For example, flow batteries in embodiments may have corrugated anode and cathode surfaces, increasing the surface area per nominal area in the x-y plane. This configuration allows flow batteries in embodiments to have higher power densities than similar configurations with flat anode and cathode surfaces. Thus, flow batteries in embodiments may be smaller and lighter than conventional batteries with comparable power output. Flow batteries in embodiments may be used in a variety of applications, including off-grid energy storage for homes or industries, and electric vehicles.

[0006] Those skilled in the art will appreciate that flow batteries can also be used to charge (or recharge) the electrolyte by connecting the flow battery to an appropriate power source and reversing the flow of electrolyte through the flow battery cells. For example, in the case of electric vehicles, depleted electrolyte can be recharged using conventional, existing electric vehicle charging systems found at homes, workplaces, commercial facilities, etc. Thus, the flow batteries of the present invention can be used to generate charged electrolyte. This is particularly advantageous for storing electricity generated by renewable energy sources in remote locations (e.g., offshore wind farms, tidal and wave power, solar panel arrays, etc.).

[0007] The electrolyte may flow between an electrolyte inlet and an electrolyte outlet. For example, charged anolyte may be supplied to the cell through the anolyte inlet and depleted anolyte may be removed from the cell through the anolyte outlet. Charged catholyte may be supplied to the cell through the catholyte inlet and depleted catholyte may be removed from the cell through the catholyte outlet. The battery may include at least one charged electrolyte storage tank; a charged anolyte storage tank; a charged catholyte storage tank; a depleted anolyte storage tank; or a depleted catholyte storage tank.

[0008] The footprint of the first conductive plate may be area A1. It will be understood that if the plate has a rectangular, flat shape, the footprint of the plate is the product of the linear length and width of the rectangle (i.e., length x width). The surface area of the first conductive plate may be area SA1. It will be understood that SA1 > A1. SA1 may be > 110% A1. SA1 may be 110% to 150% of the magnitude of A1. For example, SA1 may be approximately 110%, 120%, 130%, 140%, or 150% of A1.

[0009] The footprint of the second conductive plate may be area A2. It will be understood that if the plate has a rectangular, flat shape, the footprint of the plate is the product of the linear length and width of the rectangle (i.e., length x width). The surface area of the second conductive plate may be area SA2. It will be understood that SA2 > A2. SA2 > 110% A2 may be. SA2 may be 110% to 150% of A2. For example, SA2 may be approximately 110%, 120%, 130%, 140%, or 150% of A2. In most embodiments, A1 = A2. Also, SA1 = SA2.

[0010] The shape of the undulations along the first axis may be different from the shape of the undulations along the second axis, for example, by having a different number of peaks or troughs per unit length, and the second axis may be perpendicular to the first axis.

[0011] Each plate may have an imaginary mid-plane that contains both the first axis and the second axis, with the width and length of the plate extending within the plane and the thickness of the plate extending transversely to the plane.

[0012] The wavy surface of at least one, and preferably both, of the first and second conductive plates may include a first plurality of peaks and valleys extending along a first axis of the conductive plate and a second plurality of peaks and valleys extending along a second axis of the conductive plate.

[0013] The distance between a first plurality of peaks and adjacent valleys may be different (e.g., by at least 20%, preferably 50% or more) from the distance between a second plurality of peaks and adjacent valleys. In such a wavy configuration, the average number of peaks and valleys per unit length may be greater along the second axis than along the first axis.

[0014] The first and second conductive plates may be arranged such that their respective first axes are substantially parallel to a flow axis of electrolyte through the electrolyte flow channel, and in such a case, the distance along the first axis between a peak and an adjacent valley is preferably greater than the distance along the second axis between a peak and an adjacent valley.

[0015] The area defined between the first plate and the second plate can be thought of as a mosaic of three-dimensional shapes, each having a similar three-dimensional shape, such as a general polyhedron. The mosaic may be generally rectangular or square in shape. The mosaic may be generally hexagonal in shape. The mosaic may be more complex and may effectively utilize two or more different three-dimensional shapes. The three-dimensional shapes may be at least partially curved.

[0016] The first conductive plate and the second conductive plate are constructed and arranged such that a flow path between the plates generally in the direction of the first axis is less tortuous than a flow path between the plates generally in the direction of the second axis.

[0017] The area defined between the first and second plates is configured such that the majority of the path between the plates oriented generally along a first axis (e.g., the axis of flow) is less tortuous than the majority of the path between the plates oriented generally along a second axis (e.g., perpendicular to the axis of flow), thereby facilitating electrolyte flow between the plates and increasing the contact area between the electrolyte and the plates.

[0018] The degree of curvature of a wavy shape in a direction (e.g., along a first axis or a second axis) can be defined as the ratio of the separation between peaks and valleys in the direction of a third axis (the third axis being perpendicular to the first and second axes) to the separation between one peak and an adjacent peak in that direction.

[0019] In other words, the degree of curvature can be measured by obtaining a cross section from one peak to another in a plane that includes both the specified direction and the third axis, and using the deviation from the straight line extending between the peaks as an index.

[0020] The degree of curvature of the shape of the first plate and / or second plate along a first axis (e.g., flow axis) may be in a ratio ranging from 1:2 (i.e., more curvature) to 1:40 (i.e., less curvature), preferably in a range from 1:8 to 1:16, and optionally in a range from 1:6 to 1:25.

[0021] The degree of curvature of the shape of the first plate and / or second plate along a second axis (e.g., perpendicular to the flow axis) may be in a ratio ranging from 1:1.5 (i.e., more curvature) to 1:25 (i.e., less curvature), preferably in the range of 1:3 to 1:12, and optionally in the range of 1:2 to 1:20.

[0022] As judged by this measure, the shape of the first plate and / or second plate along the first axis is less curved than the shape along the second axis, for example, the ratio for the first axis is preferably about 150% to 300%, and optionally about 200% (i.e., about twice the ratio) of the ratio for the second axis.

[0023] For example, in one embodiment, the curvature of the surface shapes of the first plate and the second plate along a second axis (e.g., perpendicular to the flow axis) is in a ratio of 1:6, while the ratio of the curvature scale along the first axis (e.g., the flow axis) is 1:12.

[0024] Thus, the corrugations along a first axis of the conductive plate may be elongated (less curved) than the corrugations along a second axis of the plate. Corrugations that are too closely spaced (i.e., too curved) along the electrolyte flow axis may undesirably affect the flow of electrolyte through the cell. Therefore, it may be advantageous to provide tighter and / or more curved corrugations along the axis of the plate that is substantially perpendicular to the general direction of electrolyte flow.

[0025] The conductive plate may have a third axis oriented substantially perpendicular to a plane defined by the first axis and the second axis. The distance between the peaks and valleys along the third axis may be substantially equal for each of the peaks and valleys spaced apart along the first axis and the peaks and valleys spaced apart along the second axis. In some embodiments, the distance between the peaks and valleys along the third axis may be different for adjacent peaks and valleys along the first axis. The distance between the peaks and valleys along the third axis may be different for adjacent peaks and valleys along the second axis.

[0026] The peaks and valleys are preferably evenly spaced along the first axis. The peaks and valleys are preferably evenly spaced along the second axis. Each plate is preferably shaped such that any cross-section within an area parallel to the first axis and perpendicular to the second axis and extending along a majority, preferably at least 80%, of the distance across the plate along the second axis includes multiple undulations (e.g., at least two peaks and at least two valleys). Each plate is preferably shaped such that any cross-section within an area parallel to the second axis and perpendicular to the first axis and extending along a majority, preferably at least 80%, of the distance across the plate along the first axis includes multiple undulations (e.g., at least two peaks and at least two valleys).

[0027] The maximum slope relative to the nominal midplane (which may be the same as the imaginary central plane described above, extending along the first and second axes) for a cross section taken through a first plane (perpendicular to the nominal midplane and including the first axis) may be different from the maximum slope relative to the nominal midplane for a cross section taken through a second (e.g., vertical) plane (perpendicular to the nominal midplane and including the second axis). In embodiments, the magnitude of the maximum slope of the undulating surface between the peaks and valleys in a direction along the first axis may differ (e.g., by 20% or more, or even 50% or more) from the magnitude of the maximum slope of the undulating surface between the peaks and valleys in a direction along the second axis. The ratio of the large maximum slope to the small maximum slope may be between 1.5:1 and 20:1, may be greater than 2:1, or may be greater than 4:1.

[0028] Preferably, the maximum slope of the undulating surface between the peaks and valleys in a direction along the flow axis (e.g., the first axis) is less than the maximum slope of the undulating surface between the peaks and valleys in a transverse (e.g., vertical) direction (e.g., the second axis). In embodiments, the maximum slope of the anodic and cathodic surfaces is preferably greatest in a direction substantially perpendicular to the direction of electrolyte flow. Providing conductive plates with a reduced slope along the fluid flow axis is advantageous for optimizing electrolyte flow along the flow axis.

[0029] At least one of the first conductive plate and the second conductive plate may be a corrugated plate having corrugated surfaces on both sides of the plate. Both conductive plates may be corrugated plates. The corrugated plates may have a substantially uniform thickness.

[0030] The positions of the peaks of the corrugated surface on a first side of the conductive plate may correspond to the positions of the valleys of the corrugated surface on an opposite second side of the conductive plate. The positions of the valleys of the corrugated surface on the first side of the conductive plate may correspond to the positions of the peaks of the corrugated surface on the opposite second side of the conductive plate.

[0031] The flow battery may also include a third conductive plate, wherein the first conductive plate, the second conductive plate, and the third conductive plate each comprise a corrugated plate having a corrugated surface on opposing sides of the corrugated plate. For example, the second conductive plate and the third conductive plate are arranged to form a second cell of the flow battery, with the corrugated surfaces of the second conductive plate and the third conductive plate providing a cathode and a corresponding anode of the second cell and defining opposing walls of an electrolyte flow path between the second conductive plate and the third conductive plate. In such a configuration, the second conductive plate forms the anode of one of the first cell and the second cell and the cathode of the other of the first cell and the second cell.

[0032] The third conductive plate may be substantially identical in shape and / or structure to the first or second conductive plate.A flow battery may, in principle, comprise any number of conductive plates arranged to provide any number of cells, each cell being formed by at least two conductive plates having opposing corrugated surfaces that provide the cell's cathode and corresponding anode and define opposing side walls of an electrolyte flow path between the two conductive plates.

[0033] The conductive plate may be formed from a conductive composite material including a polymer and conductive filler particles. The filler particles are substantially uniformly distributed throughout the polymer. The conductive composite forms the conductive polymer core of the conductive plate. Examples of suitable polymers include acrylonitrile butadiene styrene (ABS), polysulfone (PSU), polyethersulfone (PESU), or polyphenylsulfone (PPS). Examples of suitable conductive filler particles include carbon fiber, carbon nanotubes, graphene, carbon, buckminsterfullerene, or other carbonaceous materials, semiconductors, and metallic materials. The conductive filler may be composed of a metal, a metal alloy, a semiconductor mineral, or an oxide-coated material. Alternatively or additionally, the conductive filler may include metal fibers or powders. Examples of suitable metals include gold, nickel, copper, lead, tin, iron, cobalt, magnesium, zinc, titanium, silver, aluminum, or alloys of these metals. The diameter of the conductive filler particles may be up to 50 μm, and may be generally between 7 μm and 10 μm. The volume fraction of the conductive filler particles in the conductive composite may be 2% to 50%, but may be approximately 20% to 30%. The conductive plate may be formed by injection molding, compression molding, or other manufacturing methods such as additive manufacturing or 3D printing.

[0034] The conductive plate may be manufactured by layering a conductive mesh or grid structure over a non-conductive material.

[0035] The anode and cathode surfaces of the conductive plates can be provided by techniques such as cold application, evaporation, electroplating, sputtering, or other methods of depositing metals onto a substrate, such as a conductive composite or conductive polymer core. The anode and cathode surfaces may be composed of different materials. The anode or cathode surface may include one or more of the following, in pure or alloy form: Fe, Mg, Ca, Zn, Al, Na, and Ni. Alternatively or additionally, the anode or cathode surface may be provided by a non-metal, including one or more of C, Si, or other suitable anode or cathode materials.

[0036] The flow battery may be configured to define a catholyte flow path adjacent to the cathode surface and an anolyte flow path adjacent to the anode surface. The flow battery may include one or more pumps that pump catholyte along the catholyte flow path in a first flow direction and pumps that pump anolyte along the anolyte flow path in a second flow direction. The first flow direction may be generally parallel to or opposite to the second flow direction.

[0037] The flow battery may include a separator membrane between the first and second conductive plates. The separator membrane, which is permeable to anions and cations during charging and discharging of the battery, may be formed from a permeable polymer such as polypropylene, cellulose, or the like. In some embodiments, the separator membrane may include glass fiber reinforcement. The separator membrane may include, for example, a polymer sold under the trade name "Nafion" or other suitable ion exchange membrane materials available to those skilled in the art.

[0038] Such a flow battery may be configured with a cathode flow path disposed between the separator membrane and a cathode surface disposed on a first side of the separator membrane, and an anolyte flow path disposed between the separator membrane and an anode surface disposed on a second, opposite side of the separator membrane.

[0039] In embodiments, the electrolyte flow paths may include catholyte and anolyte flow paths separated by a membrane, while in other embodiments, what are described as "membrane-free configurations," the cathode and anode define opposite walls of a single electrolyte flow path. These embodiments may include configurations in which mixing of the anolyte and catholyte is controlled by laminar flow or the use of immiscible liquids.

[0040] If a separator membrane is provided, the separator membrane may be substantially flat. If a separator membrane is provided, the separator membrane may be formed with a first plurality of undulations extending along a first axis of the membrane and a second plurality of undulations extending along a second perpendicular axis of the membrane. Such undulations formed on the membrane may be complementary in shape to the undulating surfaces of at least one of the first and second conductive plates. The membrane may be positioned such that the crests of the undulating surfaces of the membrane are received in the troughs of the undulating surfaces of at least one of the first and second conductive plates. The membrane may be positioned such that the crests of at least one of the first and second conductive plates are received in the troughs of the undulating surfaces of the membrane. The membrane may be positioned such that the crests (e.g., at least a majority of the crests, optionally all of the crests) of the undulating surfaces of the membrane are received in the troughs of the undulating surfaces of one or both of the first and second conductive plates. The membrane may be positioned such that portions of the membrane's corrugated surface (e.g., at least a majority of the valleys, optionally all of the valleys) are received within the peaks of the corrugated surface of one or both of the first and second conductive plates. The membrane may have a shape that conforms to the peaks and valleys of both the first and second conductive plates, e.g., where the shape of the peaks and valleys of the first conductive plate matches and follows the shape of the peaks and valleys of the second conductive plate. If the battery includes multiple cells formed from conductive plates with multiple corrugations, a membrane with corrugations may be provided between each of the conductive plates with corrugations.

[0041] The separator membrane may be held in place using a lattice structure. If the separator membrane is substantially flat, the lattice structure may also be substantially flat. If the separator membrane is formed in a wavy shape, the lattice structure may also have a wavy shape, or may be formed in some other way to maintain the wavy shape of the separator membrane. The lattice structure may be formed by a plurality of wavy portions having a shape complementary to the wavy portions formed in the membrane. The surface of the membrane may be supported on the lattice structure. The peaks of the lattice structure may be received in the valleys of the surface of the membrane. The peaks of the surface of the membrane may be received in the valleys of the lattice structure. The lattice structure functions as a scaffolding structure that fixes the separator membrane in place, thereby preventing the separator membrane from contacting either the anode or the cathode. The lattice structure holds the separator membrane at a fixed distance from the anode and cathode, allowing efficient ion exchange. The lattice structure is composed of a non-conductive, inert material, which may be a polymer such as acrylonitrile butadiene styrene, polyphenylene sulfide, or other polymer that remains inert in the chemical environment of a flow battery cell.

[0042] The flow batteries described and claimed herein may be relatively lightweight and have relatively high power densities. For example, the flow batteries of the present invention may be capable of delivering at least 320 watt-hours of energy per liter of electrolyte, making them particularly attractive for a variety of applications requiring energy storage.

[0043] The first cell may include a cell inlet for supplying electrolyte to the cell and a cell outlet for discharging the electrolyte from the cell. The corrugated surfaces of the first and second conductive plates may be configured so that the electrolyte flow path changes direction in the xy plane between the cell inlet and the cell outlet. Alternatively or additionally, the corrugated surfaces of the first and second conductive plates may be configured so that two or more separate electrolyte flow paths are provided between the cell inlet and the cell outlet. The corrugated surfaces may include serpentine, parallel serpentine, spiral, spiral serpentine, leaf-integrated, parallel Murray-branched, lounge-like integrated, or leaf-like surfaces. The undulating surface may define serpentine, parallel serpentine, spiral, spiral serpentine, leaf-integrated, parallel Murray branch, lounge-integrated, or leaf-like flow field(s) or channel(s).

[0044] According to a second aspect, there is provided an electric vehicle or hybrid vehicle equipped with a flow battery according to the first aspect.

[0045] The electric or hybrid vehicle may be an electric road vehicle, a watercraft, an aircraft, a spacecraft, or any other type of electric vehicle (such as an electric scooter, an electric bicycle, etc.) Such a vehicle may be equipped with one or more flow batteries configured to provide power for or assist in propelling the vehicle, preferably as the primary source of power for the vehicle, in accordance with the first aspect.

[0046] The present disclosure also provides a method for refueling a vehicle as described above. Such a method may include extracting depleted electrolyte from the vehicle using a pump at a charging station and supplying charged electrolyte to the vehicle using a pump at the charging station (which may be the same pump or a different pump). If the electric vehicle is an electric road vehicle, the infrastructure for refueling the vehicle will be very similar to current gas stations (gasoline / diesel) and may reuse existing gas stations. However, it should be noted that a flow battery can also be recharged by connecting the flow battery to an appropriate power source and reversing the flow of electrolyte through the cells. It should be understood that a vehicle typically includes one or more tanks for holding depleted electrolyte fluid and one or more tanks for holding charged electrolyte fluid. One or more flow batteries may share a common tank. For example, there may be multiple charged catholyte tanks powering a larger number of flow batteries and / or flow battery cells.

[0047] Of course, it should be understood that features described in connection with one aspect of the present teachings may be incorporated into other aspects, for example, the method may incorporate any of the features described with reference to a flow battery, and vice versa.

[0048] According to a third aspect, there is provided a conductive plate for a flow battery, the conductive plate formed from a conductive composite comprising a polymer and conductive filler particles substantially uniformly dispersed throughout the polymer, the conductive composite forming a conductive polymer core of the conductive plate, the conductive plate including a corrugated surface formed by a first plurality of corrugations extending along a first axis of the conductive plate and a second plurality of corrugations extending along a second, perpendicular axis of the conductive plate.

[0049] The conductive polymer core may have anodic and cathodic surfaces on its opposite faces, for example corrugated anodic and cathodic surfaces.

[0050] The polymer may include one or more of acrylonitrile butadiene styrene (ABS), polysulfone (PSU), polyethersulfone (PESU), or polyphenylsulfone (PPS).

[0051] The conductive filler particles may include one or more of carbon fibers, carbon nanotubes, graphene, carbon, buckminsterfullerene, or other carbonaceous materials, semiconductors, and metallic materials.

[0052] The conductive filler particles may be composed of metals, metal alloys, semiconductor minerals, or oxide coated materials.

[0053] The conductive filler particles may include metal fibers or powders.

[0054] The conductive filler particles may be composed of gold, nickel, copper, lead, tin, iron, cobalt, magnesium, zinc, titanium, silver, aluminum, or an alloy of one or more of these metals.

[0055] The diameter of the conductive filler particles may be up to 50 μm, for example, typically between 7 μm and 10 μm.

[0056] The conductive composite contains conductive filler particles, and the volume ratio thereof may be 2% to 50%, and typically 20% to 30%.

[0057] The conductive plates may be formed by injection molding, compression molding, or other manufacturing methods such as additive manufacturing or three-dimensional printing.

[0058] The conductive plate may be manufactured by layering a conductive mesh or grid structure over a non-conductive material.

[0059] The anode and cathode sides of the conductive plates may be provided by cold coating, vapor deposition, electroplating, sputtering, or other methods of depositing metal onto the conductive composite.

[0060] The anode and cathode surfaces may be composed of different materials.

[0061] The anode or cathode surface may contain one or more of the following in pure or alloy form: Fe, Mg, Ca, Zn, Al, Na, Ni.

[0062] The anodic or cathodic surface may be provided by a non-metallic material including one or more of C, Si, or other suitable anodic or cathodic materials.

[0063] The conductive plate may be a bipolar plate.

[0064] The conductive plate of the third aspect may comprise one or more of any of the features of the conductive plate of the first aspect. [Brief explanation of the drawings]

[0065] Embodiments will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:

[0066] [Figure 1] FIG. 1 is a schematic diagram of a flow battery according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram of an electric vehicle equipped with the flow battery of FIG. 1. [Figure 3] FIG. 2 is a schematic diagram showing two cells of the flow battery of FIG. 1. [Figure 4] FIG. 2 shows the bipolar plates of the battery of FIG. 1 separated. [Figure 5] 4 is a cross-sectional view of the bipolar plate of FIG. 3 taken along the longitudinal direction. FIG. [Figure 6] FIG. 4 is a cross-sectional view taken along the width direction of the bipolar plate of FIG. 3. [Figure 7] FIG. 1 is a schematic diagram showing a cell of a flow battery according to a second embodiment. [Figure 8]FIG. 8 is a schematic diagram showing the separator membrane of the cell of FIG. 7 and the polymer lattice on which the separator membrane is provided. [Figure 9A] 1A-1C illustrate some examples of wavy shapes that can be formed by conductive plates of a battery according to embodiments of the present teachings. [Figure 9B] 1A-1C illustrate some examples of wavy shapes that can be formed by conductive plates of a battery according to embodiments of the present teachings. [Figure 9C] 1A-1C illustrate some examples of wavy shapes that can be formed by conductive plates of a battery according to embodiments of the present teachings. [Figure 9D] 1A-1C illustrate some examples of wavy shapes that can be formed by conductive plates of a battery according to embodiments of the present teachings. [Figure 10A] 1A-1C illustrate examples of electrolyte flow patterns through a flow cell of a battery in accordance with the present teachings. [Figure 10B] 1A-1C illustrate examples of electrolyte flow patterns through a flow cell of a battery in accordance with the present teachings. [Figure 10C] 1A-1C illustrate examples of electrolyte flow patterns through a flow cell of a battery in accordance with the present teachings. [Figure 10D] 1A-1C illustrate examples of electrolyte flow patterns through a flow cell of a battery in accordance with the present teachings. DETAILED DESCRIPTION OF THE INVENTION

[0067] A flow battery 1 according to an embodiment is shown schematically in Figure 1. Flow battery 1 includes at least one cell. In the illustrated embodiment, flow battery 1 includes six cells 11-16, although it should be understood that any suitable number of cells may be used, for example, 1, 2, 3, 4, 5, 7, or any number of cells.

[0068] Flow battery 1 includes charged anolyte tank 20, charged catholyte tank 30, depleted anolyte collector 21, and depleted catholyte collector 31. During use, battery 1 supplies charged anolyte and charged catholyte to cells 11-16 via charged anolyte conduit 22 and charged catholyte conduit 32, respectively. Depleted anolyte is removed from cells 11-16 and supplied to anolyte collector 21 by depleted anolyte conduit 23, and depleted catholyte is removed from cells 11-16 and supplied to catholyte collector 31 by depleted catholyte conduit 33.

[0069] Battery 1 has positive and negative terminals 17 and 18 for connection to an electrical load. Flow battery 1 is particularly suited for use in electric vehicles 100, as shown in FIG. 2. For example, flow battery 1 can be retrofitted as a replacement powertrain into the existing powertrain space of an internal combustion engine or electric vehicle. To recharge electric vehicle 100, depleted anolyte and catholyte are removed from collectors 21 and 31, and charged anolyte and catholyte are provided to tanks 20, 30. However, flow battery 1 can, in principle, be used in any suitable power storage application.

[0070] Referring to FIG. 3 , each cell 11-16 includes a first conductive plate 52 and a second conductive plate 53. The first conductive plate and the second conductive plate 52, 53 provide a cathode surface 52 and an anode surface 53, respectively. Each of the first conductive plate and the second conductive plate 52, 53 defines a corrugated surface formed by a first plurality of corrugations extending along a first axis of the first conductive plate and the second conductive plate 52, 53 and a second plurality of corrugations extending along a second perpendicular axis of the first conductive plate and the second conductive plate 52, 53. The first conductive plate and the second conductive plate 52, 53 are arranged to form a cell of the flow battery 1, and the corrugated surfaces of the first conductive plate and the second conductive plate 52, 53 provide a cathode and a corresponding anode of the cell and define opposing walls of an electrolyte flow path between the first conductive plate and the second conductive plate 52, 53.

[0071] The first and second conductive plates 52, 53 may be arranged such that the peaks (e.g., at least a majority of the peaks, optionally all of the peaks) of the wavy surface of the first conductive plate 52 are received in or aligned with the valleys of the wavy surface of the second conductive plate 53 of each cell 11-16. The first and second conductive plates 52, 53 may be arranged such that the valleys (e.g., at least a majority of the peaks, optionally all of the peaks) of the first conductive plate 52 are received in the peaks of the second conductive plate 53 of each cell 11-16.

[0072] Each of the battery's cells 12-15 is formed by a pair of bipolar plates 50. In other words, the first conductive plate and / or the second conductive plate may be a bipolar plate 50. Each bipolar plate 50 includes a cathode surface 52 and an anode surface 53. The cathode surface of each of the cells 12-15 is provided by a first bipolar plate 50, and the anode surface 53 is provided by a second bipolar plate 50 spaced apart from the first bipolar plate 50. This bipolar plate configuration is best shown in FIG. 3, which shows two of the battery's cells 13, 14 in isolation. Each of the two cells 13, 14 is formed by three bipolar plates 50.

[0073] Each bipolar plate 50 includes a conductive polymer core 51. The conductive polymer core 51 may be formed from a conductive composite. The conductive composite may include a polymer and conductive filler particles dispersed substantially uniformly throughout the polymer. The polymer may include one or more of acrylonitrile butadiene styrene (ABS), polysulfone (PSU), polyethersulfone (PESU), or polyphenylsulfone (PPS). The conductive filler particles may include one or more of carbon fiber, carbon nanotubes, graphene, carbon, buckminsterfullerene, or other carbonaceous material, semiconductor, or metallic material. The conductive filler particles may include a metal, a metal alloy, a semiconductor mineral, or an oxide-coated material. The conductive filler particles may include metal fibers or powders. The conductive filler particles may include gold, nickel, copper, lead, tin, iron, cobalt, magnesium, zinc, titanium, silver, aluminum, or an alloy of one or more of these metals. The diameter of the conductive filler particles may be up to 50 μm, typically between 7 μm and 10 μm. The conductive composite may contain the conductive filler particles, and their volume fraction may be 2% to 50%, typically between 20% and 30%. In some embodiments, the anode or cathode surfaces, i.e., the first and second conductive plates, may contain one or more of the following, in pure or alloy form: Fe, Mg, Ca, Zn, Al, Na, and Ni. Alternatively, the anode or cathode surfaces 52, 53 may be provided by non-metals including one or more of C, Si, or other suitable anode or cathode materials.

[0074] In this embodiment, the conductive polymer core may be formed from injection-molded acrylonitrile butadiene styrene (ABS) containing approximately 20% by volume of uniformly dispersed zinc particles. Both sides of the conductive polymer core 51 are coated with a conductive zinc coating, thereby providing a cathode surface 52 on one side of the bipolar plate 50 and an anode surface 53 on the other side of the bipolar plate 50. In other embodiments, the conductive polymer core may be formed from other suitable conductive polymer arrangements, and other conductive coatings may be used to provide the anode and cathode surfaces.

[0075] Each cell 11-16 has a flat sheet separator membrane 54 of Nafion disposed between a cathode surface 52 and an anode surface 53. The space between membrane 54 and cathode surface 52 is filled with catholyte 56, and the space between membrane 54 and anode surface 53 is filled with anolyte 57. The electrolyte used for the catholyte and anolyte is bipolar zinc polyiodide. In other embodiments, other suitable electrolytes may be used.

[0076] Battery 1 is configured so that catholyte 56 and anolyte 57 flow from top to bottom through the cell, as indicated by the arrows in FIG. 3 , in the cell orientation shown in FIGS. 1 and 3 . Thus, a catholyte flow path is defined between membrane 54 and cathode surface 52, and an anolyte flow path is defined between membrane 54 and anode surface 53. Cells 12-15, which have adjacent cells on both sides, are each arranged in this manner. Meanwhile, cells 11 and 16, which have adjacent cells on only one side, are formed by one bipolar plate and one monopolar plate. Specifically, cell 16 has a cathode surface 52 provided by the bipolar plate shared with adjacent cell 15, and an anode surface provided by the monopolar plate. Cell 11 has an anode surface 53 provided by the bipolar plate shared with adjacent cell 12, and a cathode surface provided by the monopolar plate. Monopolar plates may be arranged similarly to bipolar plates 50, but with a conductive coating on only one side to provide a cathode or anode, as desired.

[0077] Each bipolar plate 50 includes a conductive polymer core 51 formed by a plate having corrugations extending along the plate's length axis y and along the plate's width axis x. Thus configured, the conductive polymer core 51 includes a plurality of peaks and valleys arranged in the xy plane. This configuration allows the conductive polymer core 51 to resemble a typical egg crate. The x- and y-axes defining the nominal plane of the conductive polymer core 51 are shown in FIG. 4 , with the z-axis extending perpendicular to the xy plane. The corrugations increase the area of the cathode surface 52 and the anode surface 53, thereby increasing the power density of the battery 1 compared to a similar battery having flat cathode and anode surfaces.

[0078] FIG. 5 shows a cross-sectional view of one of the bipolar plates 50 taken along the y-z plane. As can be seen, the corrugations provide the conductive polymer core 51 with a plurality of peaks 501 and valleys 502 spaced apart along the y-axis of the plate (the axis along which the electrolyte flows in use). Similarly, a cross-sectional view of the bipolar plate 50 taken along the x-z plane is shown in FIG. 6. As can be seen, the corrugations also provide the conductive polymer core 51 with a plurality of peaks 501 and valleys 502 spaced apart along the x-axis of the plate (the axis oriented transverse to the axis along which the electrolyte flows in use). As shown in FIGS. 5 and 6, the distance A between a peak 501 and an adjacent valley 502 along the y-axis of the plate is greater than the distance B between a peak 501 and an adjacent valley 502 along the y-axis of the plate, which means that the number of peaks 501 and valleys 502 per unit width W of the conductive polymer core 51 is greater than the number of peaks 501 and valleys 502 per unit length L of the conductive polymer core 51. In this case, the height V measured along the z-axis between the peaks 501 and valleys 502 is constant everywhere, so that the magnitude of the maximum gradient of the conductive polymer core 51 along its width is greater than the magnitude of the maximum gradient of the conductive polymer core 51 along its length. In other words, the corrugations of the conductive polymer core 51 are steeper along the x-axis than along the y-axis. While providing the cathode and anode surfaces 52 and 53 with corrugations increases the surface area of each surface, thereby increasing the power density of the battery, the corrugations also increase the tortuosity of the electrolyte flow paths between the surfaces. Corrugations that are too closely spaced along the electrolyte flow paths or that have too steep a slope of the plates along the paths can excessively restrict fluid flow and adversely affect the performance of the flow battery. However, there is essentially no electrolyte flow along the x-axis over the majority of the cathode and anode surfaces 52 and 53. Thus, the bipolar plates of the battery are arranged to increase the surface area of the cathode and anode by providing a higher density of corrugations along the x-axis, which is a direction substantially perpendicular to the general axis of electrolyte flow, than along the y-axis, which is a direction substantially parallel to the axis of electrolyte flow.While the conductive polymer core 51 of each bipolar plate described herein is configured with an arrangement of egg-crate-shaped truncated pyramidal corrugations, in other embodiments, it may be configured with other types of corrugations in the xy plane to increase the surface area of the plate. Referring to Figures 9A-9D, these may include hemispherical 701, conical 702, frustoconical 703, pyramidal 704, or other suitable shapes.

[0079] Cell 313 of the bipolar battery according to the second embodiment is shown in Figure 7. Cell 313 has many features in common with cell 13 of the battery according to the first embodiment, so where cell 313 has features described with respect to cell 13, those features are given the same reference numerals but preceded by the number "3."

[0080] The cell 313 is formed by bipolar plates 350 and filled with catholyte 35 and anolyte 357. Cell 313 differs from cell 13 of the first embodiment battery in that the separator membrane 60 of cell 313 has been heat-pressed to form a plurality of corrugations complementary to those formed in the conductive polymer core 351 of the bipolar plates. The membrane 60 has a substantially uniform thickness, with peaks 61 and 63 on one side of the membrane 60 corresponding to valleys 62 and 64 on the other side of the membrane. As shown in FIG. 8 , the membrane 60 is held in its corrugated shape by a polymer lattice 70 on which the membrane 60 is disposed. The lattice 70 acts as a scaffolding structure, securing the separator membrane 60 in place at a fixed distance from the cathode and anode faces 352 and 353, enabling efficient ion exchange. The lattice structure is constructed from acrylonitrile butadiene styrene, but in other embodiments may be constructed from other non-conductive materials that remain inert in the chemical environment of the flow battery cell.

[0081] The corrugations of the separator membrane 60 align with the corrugations of the conductive polymer core 351, such that on the cathode side of the separator membrane 60, the peaks 61 formed by the separator membrane 60 are received in the valleys 3502 formed by the cathode surface 352, and the peaks 3503 formed by the cathode surface 352 are received in the valleys 64 formed by the separator membrane 60. On the anode side of the separator membrane 60, the peaks 63 formed by the separator membrane 60 are received in the valleys 3504 formed by the anode surface 353, and the peaks 3505 formed by the anode surface 353 are received in the valleys 62 formed by the separator membrane 60. The corrugated membrane 60 configured in this manner allows the cathode surface 352 and the anode surface 353 to be positioned closer together than in an arrangement with a flat membrane 54. Therefore, the corrugated membrane 60 allows for a smaller battery size compared to an arrangement with a flat membrane.

[0082] In some embodiments, the plates may be provided with corrugations arranged to direct the electrolyte between the cell inlet 800 and the cell outlet 801 through one or more electrolyte flow paths, or alternatively or additionally, the plates may change direction in the xy plane between the cell inlet 800 and the cell outlet 801 through the electrolyte flow paths, causing the electrolyte to flow along a non-linear path in the xy plane between the cell inlet 800 and the cell outlet 801. Such a configuration may be advantageous for controlling the fluid flow rate through the battery's cells to allow longer exposure of ions to the cathode and anode faces, thereby optimizing the energy extracted from the electrolyte and ensuring that the electrolyte is fully depleted by the time it reaches the cell outlet 801.

[0083] In some embodiments, the corrugations of the bipolar plates, and optionally the membranes between the plates, may be shaped to restrict the net fluid flow between the cell inlets 800 and cell outlets 801 to a spiral channel 805 in the xy plane, as shown in FIG. 10A, or a serpentine channel 806, as shown in FIG. 10B. In embodiments including a membrane, the membrane may have corrugations complementary to the corrugations of the bipolar plates, and the membrane may be positioned equidistant between the bipolar plates. In other embodiments, the corrugations of the bipolar plates, and optionally the membranes between the plates, may be shaped to direct the fluid flow between the cell inlets and outlets along multiple channels 807, such as a parallel Murray pattern as shown in FIG. 10C or a parallel pattern as shown in FIG. 10D.

[0084] Where the foregoing description refers to integers or elements that have known, obvious, or foreseeable equivalents, such equivalents are incorporated herein as if individually defined. Also, it should be understood that integers or features described as preferred, advantageous, convenient, etc. are optional and do not limit the scope of the claims. Furthermore, it should be understood that such optional integers or features may be beneficial in some embodiments, but may be undesirable and therefore absent in other embodiments.

Claims

1. A flow battery comprising: a first conductive plate; a second conductive plate; each of the first and second conductive plates having a corrugated surface formed with a first plurality of undulations extending along a first axis of each conductive plate and a second plurality of undulations extending along a second axis perpendicular thereto; the first conductive plate and the second conductive plate are arranged to form a first cell of a flow battery; In the first cell, the corrugated surfaces of the first conductive plate and the second conductive plate are configured to provide a cathode and a corresponding anode of the first cell, respectively, and to define opposing walls of an electrolyte flow path between the first conductive plate and the second conductive plate.

2. The wavy surface of at least one of the first conductive plate and the second conductive plate comprises: a plurality of first peaks and valleys extending along the first axis of the at least one of the first conductive plate and the second conductive plate; a plurality of second peaks and valleys extending along the second axis of the at least one of the first conductive plate and the second conductive plate; 10. The flow battery of claim 1, wherein a distance between a peak and an adjacent valley in the first plurality of peaks and valleys differs (e.g., by at least 20%) from a distance between a peak and an adjacent valley in the second plurality of peaks and valleys.

3. the first conductive plate and the second conductive plate are arranged such that the first axis of each is substantially parallel to a flow axis of electrolyte flow through an electrolyte flow channel; 3. The flow battery of claim 2, wherein a distance along the first axis between a peak and an adjacent valley of the first plurality of peaks and valleys is greater than a distance along the second axis between a peak and an adjacent valley of the second plurality of peaks and valleys.

4. The wavy surface of at least one of the first conductive plate and the second conductive plate comprises: a plurality of first peaks and valleys extending along the first axis of the at least one of the first conductive plate and the second conductive plate; a plurality of second peaks and valleys extending along the second axis of the at least one of the first conductive plate and the second conductive plate; 4. The flow battery of claim 1, wherein a magnitude of a maximum slope of the wavy surface between a peak and a valley among the plurality of first peaks and valleys is different from a magnitude of a maximum slope of the wavy surface between a peak and a valley among the plurality of second peaks and valleys.

5. the first conductive plate and the second conductive plate are arranged such that the first axis of each is substantially parallel to a flow axis of electrolyte flow through the electrolyte flow channel; 5. The flow battery of claim 4, wherein a magnitude of the maximum slope of the wavy surface between a peak and a valley of the first plurality of peaks and valleys is less than a magnitude of the maximum slope of the wavy surface between a peak and a valley of the second plurality of peaks and valleys.

6. 6. The flow battery of any of the preceding claims, wherein at least one of the first conductive plate and the second conductive plate is a corrugated plate having corrugated surfaces on both sides.

7. a third conductive plate; the second conductive plate and the third conductive plate are arranged to form a second cell of the flow battery; the corrugated surfaces of the second and third conductive plates provide a cathode and a corresponding anode of the second cell and define opposing walls of an electrolyte flow path between the second and third conductive plates; 7. The flow battery of claim 6, wherein the second conductive plate thereby forms an anode of one of the first cell and the second cell and a cathode of the other of the first cell and the second cell.

8. 8. The flow battery of claim 6 or claim 7, wherein the second conductive plate is configured to be a bipolar plate including a conductive polymer core including a corrugated anode surface and a corrugated cathode surface on opposite sides thereof.

9. 10. The flow battery of claim 8, wherein the conductive polymer core comprises a conductive composite comprising a polymer and conductive filler particles dispersed substantially uniformly throughout the polymer.

10. The flow battery comprises: a catholyte flow channel adjacent to the cathode surface; an anolyte flow channel adjacent to the anode surface; one or more pumps for pumping the catholyte in a first flow direction along the catholyte flow path and for pumping the anolyte in a second flow direction along the anolyte flow path; 10. The flow battery of any one of claims 1 to 9, wherein the first flow direction is generally parallel to but opposite to the second flow direction.

11. a separator membrane between the first conductive plate and the second conductive plate, whereby a catholyte flow path is provided on a first side of the separator membrane between a cathode surface and the separator membrane; 11. The flow battery of claim 1, wherein an anolyte flow path is provided between an anode surface and the separator membrane on a second, opposite side of the separator membrane.

12. the separator membrane has a plurality of first undulations extending along a first axis of the separator membrane; 12. The flow battery of claim 11 , wherein the separator membrane is formed including a plurality of second corrugations extending along a second perpendicular axis of the separator membrane.

13. the wavy portion formed on the separator film has a shape complementary to the wavy surface of at least one of the first conductive plate and the second conductive plate; 13. The flow battery of claim 12, wherein the separator membrane is positioned such that crests of a corrugated surface of the separator membrane are received in troughs of the corrugated surface of at least one of the first conductive plate and the second conductive plate, or such that crests of at least one of the first conductive plate and the second conductive plate are received in troughs of the corrugated surface of the separator membrane.

14. 14. The flow battery of claim 12 or 13, wherein the separator membrane is supported by a lattice structure.

15. 15. The flow battery of claim 14, wherein the lattice structure is formed to include a plurality of undulations having shapes complementary to the undulations formed in the separator membrane, and wherein a surface of the separator membrane is supported on the lattice structure such that peaks of the lattice structure are received in valleys of the surface of the separator membrane and peaks of the surface of the separator membrane are received in valleys of the lattice structure.

16. the first cell having a cell inlet through which electrolyte is supplied to the cell; a cell outlet through which electrolyte is discharged from the first cell; 16. The flow battery of any one of claims 1-15, wherein the undulating surfaces of the first and second conductive plates are configured such that the electrolyte flow path changes direction in an xy plane between the cell inlet and the cell outlet.

17. the first cell having a cell inlet through which electrolyte is supplied to the cell; a cell outlet through which electrolyte is discharged from the first cell; 17. The flow battery of any one of claims 1 to 16, wherein the corrugated surfaces of the first conductive plate and the second conductive plate are configured to provide two or more electrolyte flow paths between the cell inlet and the cell outlet.

18. 1. A conductive plate formed from a conductive composite for a flow battery, comprising: The conductive composite material comprises: A polymer, and conductive filler particles dispersed substantially uniformly throughout the polymer; the conductive composite forms a conductive polymer core of the conductive plate; The conductive plate includes a wavy surface formed by a plurality of first undulations extending along a first axis of the conductive plate and a plurality of second undulations extending along a second axis of the conductive plate perpendicular thereto.

19. 20. The conductive plate of claim 18, wherein the polymer comprises one or more of acrylonitrile butadiene styrene (ABS), polysulfone (PSU), polyethersulfone (PESU), or polyphenylsulfone (PPS).

20. 20. The conductive plate according to claim 18 or 19, comprising 2% to 50%, for example 20% to 30%, by volume of conductive filler particles.

21. A conductive plate according to any one of claims 18 to 20, wherein the conductive filler particles are configured to have a diameter of up to 50µm, for example typically between 7µm and 10µm.

22. 22. The conductive plate according to claim 18, wherein the conductive polymer core comprises a conductive coating on opposing faces thereof and on one or both of the opposing faces, forming an anode and / or cathode face of the conductive plate.

22. 18. A vehicle comprising a flow battery according to any one of claims 1 to 17, for example configured such that the vehicle is a road vehicle, optionally an electric vehicle or a hybrid vehicle.

23. 23. A vehicle as claimed in claim 22, wherein one or more flow batteries as claimed in any one of claims 1 to 17 are configured to provide power for or assist in the propulsion of the vehicle; Optionally, a vehicle configured such that a primary power source of said vehicle is one or more flow batteries according to any of claims 1 to 17.

25. 25. A method of refueling a vehicle according to claim 23 or claim 24, comprising the steps of: extracting depleted electrolyte fluid from the vehicle using a pump at a charging station; and supplying charged electrolyte fluid to the vehicle using a pump at the charging station.

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