Electrochemical cell with electrolyte management
By adopting a basically horizontal discharge cathode design and uniform circulation of liquid electrolytes in electrochemical batteries, the problems of zinc bed depletion and uneven circulation of liquid electrolytes in existing electrochemical batteries are solved, and the battery efficiency and cathode are improved Lifespan reduces the occurrence of adverse side effects.
Patent Information
- Application Number
- CN202380049275.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-06-23
- Filing Date
- 2023-06-07
- Publication Date
- 2025-02-11
AI Technical Summary
In existing electrochemical cells, the vertical arrangement of the discharge cathode causes zinc bed depletion, reduces cell efficiency, shortens cathode life, and uneven circulation of liquid electrolytes leads to component passivation and adverse side reactions.
A discharge cathode design is adopted that is placed substantially horizontally so that the zinc bed is deposited above the cathode during charging operations, and the entire cathode surface is evenly covered by the zinc bed. During discharge operations, zinc is depleted from the bottom and replaced by a more bottom zinc bed, ensuring uniform utilization of the cathode surface. Furthermore, the design allows for a more uniform circulation of the liquid electrolyte through the arrangement of the recirculation inlet and fluid conduit along the length of the battery.
Improve battery efficiency, extend the life of the discharge cathode, and reduce the occurrence of component passivation and adverse side reactions by uniformly circulating liquid electrolytes.
Smart Images
Figure CN119422272A_ABST
Abstract
Description
[0001] CROSS-REFERENCE TO RELATED APPLICATIONS
[0002] This application claims priority to U.S. Provisional Patent Application USSN 63 / 354,726, filed on June 23, 2022, the entire contents of which are incorporated herein by reference. Technical Field
[0003] The present application relates to electrochemical cells. Background Art
[0004] A typical charge / discharge type electrochemical cell includes a tank containing a liquid electrolyte reservoir, wherein electrodes (cathode and anode) are located, the tank accommodating a discharge portion generally located at or near the bottom of the tank and a charge portion generally located at or near the top of the tank, with a storage portion of the liquid electrolyte located between the charge portion and the discharge portion. The charge portion is used to store electrical energy in the electrochemical cell, and the discharge portion is used to deliver the stored electrical energy to operate an electrical device. The charge portion and the discharge portion are generally not operated simultaneously. Charge / discharge type electrochemical cells generally utilize Zn / Zn in an alkaline aqueous electrolyte. 2+ Half-cell reaction. The charging portion includes a charging anode and a charging cathode, at which the following chemical reactions occur during the charging operation:
[0005] Charging anode: 4OH - →O2+2H2O+4e -
[0006] Charging cathode:
[0007] The discharge part includes a discharge anode and a discharge cathode, and the following chemical reactions occur during the discharge operation:
[0008] Discharge anode:
[0009] Discharge cathode: O2+2H2O+4e - →4OH -
[0010] The solid zinc formed at the charged cathode falls to the bottom of the electrochemical cell under the action of gravity to collect on the metal current collector. When the electrochemical cell is in the discharge operation, the solid zinc is converted back to When the current is high, the metal collector carries the current and makes the electrical equipment operate.
[0011] The discharge cathode is usually placed vertically in the cell. During the charging operation, a solid bed of zinc forms around the discharge cathode and during the discharge process, the solid bed of zinc is depleted from around the discharge cathode. There are many problems with this arrangement. The depletion of the zinc bed around the discharge cathode increases the distance between the discharge cathode and the zinc, thereby reducing the efficiency of the cell and shortening the life of the discharge cathode, especially when the discharge cathode is an air cathode. The vertically oriented discharge cathode acts as a baffle to prevent the solid zinc and electrolyte in the cell from moving from one side to the other during the discharge operation, resulting in differential consumption of the zinc bed. The differential consumption of the zinc bed is also exacerbated by the different discharge cathode performances in the vertical discharge cathode orientation, which essentially consume the zinc in the zinc bed at different rates. Another consequence of the above is that different concentrations of zinc salts are formed in different areas of the battery electrolyte, resulting in voltage differences at each discharge cathode, exacerbating the differential consumption of zinc problem. Another problem associated with the vertical discharge cathode is that during the charging operation, the discharge cathode inhibits the solid zinc from falling to the bottom of the cell and some solid zinc accumulates on the upper edges of the vertically oriented discharge cathode, which are not the electrochemically active parts of the discharge cathode. All of these problems result in inefficient use of zinc and unreacted solid zinc during discharge operations.
[0012] Recirculation of electrolyte is an important feature of electrochemical cells containing electrolytes, especially cells where liquid electrolytes are prone to forming concentration gradients. If recycling is inadequate, component passivation and undesirable side reactions may occur.
[0013] There remains a need for electrochemical cell designs and discharge cathodes thereof that more efficiently utilize solid zinc and more effectively manage liquid electrolyte during discharge operations. Summary of the invention
[0014] An electrochemical cell having a discharge cathode disposed substantially horizontally so that during charging operation a solid zinc bed is deposited above the discharge cathode rather than beside the discharge cathode to cover the entire discharge cathode. During the discharge operation, the zinc bed is depleted, but throughout the discharge operation, substantially the entire surface of the discharge cathode is covered with the zinc bed because zinc is depleted from the bottom and the depleted zinc is continuously replaced by more zinc in the bed under the action of gravity. Thus, gravity causes the zinc bed (i.e., the anode) to be evenly distributed over the anode current collector and the discharge cathode.
[0015] Additionally, the discharge cathode design allows for greater modularity in the electrochemical cell, allowing the storage portion to be separated from the discharge portion.
[0016] In addition, the discharge cathode design allows for fluid communication with multiple internal fluid conduits using a series of recirculation inlets along the length of the cell, thereby circulating the liquid electrolyte throughout the cell in a more uniform manner. In this regard, the discharge cathode design is also useful in configurations where the discharge cathode is not substantially horizontal, but the design is particularly useful in electrochemical cells where the discharge cathode and separator are closely spaced and the liquid electrolyte is recirculated from the area between the separator and the discharge cathode to an area of the cell outside the area between the separator and the discharge cathode, for example, the top of the liquid electrolyte reservoir.
[0017] A cathode assembly for an electrochemical cell is provided, the cathode assembly comprising: an air cathode subassembly configured to accommodate a gaseous oxygen (O2) cathode material in a gas volume, the air cathode subassembly comprising: a frame defining an edge of the gas volume; a base plate defining a first side of the gas volume; at least one recirculation outlet in the air cathode subassembly; and, a plurality of internal fluid conduits contained in the frame, configured to collect liquid electrolyte from outside the gas volume to direct the collected liquid electrolyte to at least one recirculation outlet through which the liquid electrolyte leaves the air cathode subassembly; and, an air cathode fixed to the frame to confine a second side of the gas volume, the plurality of internal fluid conduits configured to collect liquid electrolyte along an edge of the air cathode.
[0018] The cathode assembly is suitable for use in any type of electrochemical cell. When used in a charge / discharge type electrochemical cell, the cathode assembly is a discharge cathode assembly.
[0019] The present invention provides an electrochemical cell, comprising: an anode comprising a solid anode material; a liquid electrolyte in physical contact with the solid anode material; an air cathode comprising a gaseous oxygen (O2) cathode material, the air cathode being at an angle of 45 degrees or less relative to the horizontal when used in the cell; an air cathode subassembly configured to contain gaseous oxygen in a gas volume, the air cathode being sealed and mounted in the air cathode subassembly and separating the gas volume from the liquid electrolyte above the gas volume, the gaseous oxygen being able to diffuse from the gas volume into an interface region of the air cathode where the gaseous oxygen contacts the liquid electrolyte; a separator comprising an electrically insulating material, the separator separating the air cathode from the anode material, the separator being permeable to the liquid electrolyte and the separator being impermeable to the solid anode material; and an electrolyte management subsystem comprising at least one fluid conduit that collects the liquid electrolyte from between the air cathode and the separator and recirculates the collected electrolyte into the liquid electrolyte above the separator.
[0020] In the following detailed description, further features will be described or made apparent. It should be understood that each feature described herein can be used in any combination with any one or more other described features, and each feature does not necessarily rely on the presence of another feature, unless it is obvious to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] For a clearer understanding, the preferred embodiments are now described in detail with reference to the accompanying drawings, in which:
[0022] Figure 1 A perspective view of an electrochemical cell is depicted.
[0023] Figure 2 Depicted Figure 1 Side cross-sectional view of an electrochemical cell.
[0024] Figure 3 Describes passing through Figure 1 Rear cross-sectional view of the rear rain showerhead of the electrochemical cell.
[0025] Figure 4 Depicted Figure 1 A front isometric perspective view of the discharge portion of an electrochemical cell.
[0026] Figure 5 Depicted Figure 4 Front isometric view of the discharge portion of FIG. 1 with the anode current collector, separator, flange and air cathode removed.
[0027] Figure 6 Depicted Figure 4 A rear isometric perspective view of a discharge portion of FIG. 1 with multiple layers partially removed to illustrate the relationship between the multiple layers.
[0028] Figure 7 Depicted Figure 4 A simplified top view of a discharge portion of FIG. 1 , wherein multiple layers are partially removed to illustrate the relationship between the multiple layers.
[0029] Figure 8 Depicted Figure 3 A simplified view of a 3D image with several components removed.
[0030] Fig. 9 Depicted Figure 8 An enlarged view of one side of the depicted view.
[0031] Fig.10 Depicted Figure 2 A simplified schematic diagram of a device with various components removed shows how air is supplied to the gas volume of the air cathode subassembly.
[0032] Fig.11 Depicted Fig.10 An enlarged view of one side of the depicted view.
[0033] Fig.12 Depicted Figure 4 A perspective view of the recirculation duct in the base of the discharge section.
[0034] Fig.13 Depicted Fig.12 An enlarged view of a portion of the central portion.
[0035] Fig.14 Depicted Figure 4 A top view of the base of the discharge portion of FIG. 1 with the anode current collector, separator and air cathode removed. DETAILED DESCRIPTION
[0036] As used herein, an anode material is a chemical substance that is oxidized (i.e., loses electrons) in a half-cell reaction. The anode material in the discharge portion of the electrochemical cell preferably comprises a metal, such as metallic zinc, copper, lead, etc. The negative electrode material is more preferably zinc metal. The anode material is preferably granular, forming a bed of anode material particles above the separator. The bed of anode material particles is porous to allow liquid electrolyte to flow through the bed to the separator.
[0037] As used herein, the anode is a physical structure that contains the anode material and is where the anode half-cell reaction involving the anode material occurs. In the discharge portion of the electrochemical cell, the anode comprises a bed of anode material. The bed of anode material preferably covers the separator.
[0038] As used herein, an anode current collector is a physical structure comprising a conductive material for transmitting electrons from an anode material. The electrochemical cell preferably includes an anode current collector located below the anode material and in physical contact with the anode material. The anode current collector is preferably a porous conductive metal mesh. The metal preferably includes nickel or copper.
[0039] As used herein, a cathode material is a chemical species that is reduced (i.e., gains electrons) in a half-cell reaction. The cathode material of the discharge portion of the electrochemical cell preferably comprises an oxidizing gas, preferably gaseous oxygen. The gaseous oxygen is preferably provided in the form of air, more preferably in the form of air from which carbon dioxide has been removed.
[0040] As used herein, a cathode is a physical structure in which a cathode half-cell reaction involving a cathode material occurs. When the cathode material is an oxidizing gas (e.g., gaseous oxygen), the cathode material resides in the cathode prior to the reaction and is continually replenished to the cathode as the cathode material reacts.
[0041] As used herein, a cathode current collector is a physical structure comprising a conductive material for transporting electrons to a cathode material. The anode current collector is preferably a porous metal mesh. The metal preferably comprises nickel or copper.
[0042] As used herein, an air cathode is a cathode comprising a cathode current collector and an active layer containing an electrochemically active catalyst for a cathode half-cell reaction. The catalyst is preferably disposed in the active layer together with conductive carbon and a binder, preferably a hydrophobic binder (e.g., polytetrafluoroethylene (PTFE)). Preferably, the active layer is laminated to the anode current collector. In some embodiments, the air cathode further comprises a backing layer of a hydrophobic material (e.g., PTFE or a mixture of PTFE and conductive carbon). The air cathode comprises an interface region in which the catalyst is located. In the interface region, the liquid electrolyte and gaseous oxygen contact each other and a cathode half-cell reaction occurs. Therefore, the liquid electrolyte, the catalyst, and the gaseous oxygen form a three-phase boundary in the interface region, where the gaseous oxygen reacts to form hydroxide ions.
[0043] As used herein, a separator is a physical structure comprising a porous electrically insulating material. The separator electrically separates the cathode from the anode material. The separator preferably covers the cathode to prevent the anode material from directly contacting the cathode. The separator preferably has a perimeter that is sealed to the housing along the perimeter to prevent solid anode material from entering the electrolyte management subsystem and to ensure that the liquid electrolyte must penetrate through the separator to reach the interface area. The separator is permeable to the liquid electrolyte but not to the solid anode material. In this regard, the separator also acts as a filter. The separator preferably has a porosity to create a pressure differential between the top and bottom of the separator, thereby causing the liquid electrolyte to penetrate more evenly through the separator toward the cathode over the entire surface area of the separator. The separator preferably comprises a mat made of polypropylene fibers. The mat preferably has a density of 20-100 g / m 3 Density within the range, for example 60g / m 3 The mat preferably has a thickness in the range of 80 to 300 microns, for example 180 microns. The air permeability of the mat is preferably 100 to 500 dm 3 / sec·m 2 .
[0044] As used herein, a liquid electrolyte is a liquid medium containing anions that can react with an oxidized anode material to form anionic metal complexes. Preferably, the liquid medium is an aqueous medium. Preferably, the anions are hydroxide ions, which can be present in a solution in an aqueous medium, such as by dissolving an alkali metal hydroxide (e.g., NaOH, KOH) in water to form an aqueous solution of hydroxide ions. When the anode material is oxidized, the hydroxide ions react with the metal cations to form a metal complex. In the case of Zn / Zn 2+In electrochemical cells, metal compounds are the electrolyte solutions with Na+ or K+ counterions.
[0045] The air cathode is fixed to the air cathode subassembly to form a cathode assembly. The air cathode subassembly is preferably configured to contain gaseous oxygen in the gas volume. The air cathode subassembly thus acts as a storage unit for gaseous oxygen. The air cathode is preferably sealed and mounted in the air cathode subassembly and separates the gas volume from the liquid electrolyte above the gas volume. The gaseous oxygen diffuses from the gas volume to the interface region of the air cathode, where the gaseous oxygen contacts the liquid electrolyte. Therefore, the cathode assembly preferably includes a frame defining the edge of the gas volume, a bottom plate defining the first side of the gas volume, and an air cathode fixed to the frame to define the second side of the gas volume. In some embodiments, the air cathode subassembly also includes a base defining the bottom plate and the frame, and the cathode assembly includes a flange removably connected to the top of the bottom base. The flange can be configured to support a wall for accommodating a liquid electrolyte in an electrochemical cell.
[0046] In some embodiments, the air cathode subassembly includes a plurality of bridges positioned in the gas volume to support the air cathode thereon. In some embodiments, the air cathode subassembly includes at least one gas port for introducing gaseous oxygen into the gas volume. In some embodiments, the air cathode subassembly is configured to sealingly support a wall thereon for containing a liquid electrolyte in the electrochemical cell, and in some embodiments, the wall is positioned above the separator.
[0047] In some embodiments, the air cathode is positioned substantially horizontally, that is, at an angle of 45° or less relative to the horizontal when the cathode assembly is used in an electrochemical cell. In these embodiments, the second side of the gas volume, that is, the air cathode, is located above the gas volume, and the first side of the gas volume, that is, the bottom plate of the air cathode subassembly, is located below the gas volume. Preferably, the angle is 20° or less. In some embodiments, the angle is 0°, in which case the air cathode is completely horizontal. In some embodiments, the angle is in the range of 1-20°. Different portions of the air cathode can be at different angles relative to the horizontal plane. In some embodiments, the air cathode is peaked to minimize sagging of the air cathode. Similarly, the separator and / or anode current collector can be peaked to minimize sagging of the separator and / or anode current collector and promote the flow of liquid electrolyte to the outer edge of the separator.
[0048] The electrochemical cell includes an electrolyte management subsystem. The electrolyte management subsystem includes internal components inside the electrochemical cell and structural elements of various components of the electrochemical cell, such as the charging and discharging parts of a charge / discharge type electrochemical cell. The electrolyte management subsystem also includes external components outside the electrochemical cell.
[0049] The electrolyte management subsystem includes internal and external components associated with the air cathode subassembly. In this regard, the air cathode subassembly preferably includes at least one fluid conduit contained in the frame, preferably a plurality of internal fluid conduits, configured to collect liquid electrolyte from outside the gas volume. The at least one fluid conduit preferably directs the collected liquid electrolyte to at least one recirculation outlet through which the liquid electrolyte leaves the air cathode subassembly. Preferably, the at least one fluid conduit includes a fluid conduit manifold, the fluid conduit manifold including a plurality of internal fluid conduits in fluid communication with the liquid electrolyte between the air cathode and the separator. The plurality of internal fluid conduits preferably have a plurality of recirculation inlets located between the air cathode and the separator for collecting liquid electrolyte from an edge of the air cathode outside the gas volume and directing the collected liquid electrolyte to at least one recirculation outlet through which the liquid electrolyte leaves the air cathode subassembly. In some embodiments, the air cathode subassembly includes at least one exhaust port. Preferably, the bottom plate is configured to direct liquid electrolyte leaking into the gas volume toward the at least one exhaust port.
[0050] In some embodiments, the electrolyte management subsystem includes at least one external fluid conduit in fluid communication with at least one recirculation outlet. The at least one external fluid conduit is preferably connected to at least one fluid pump operable to pump the collected liquid electrolyte through the at least one external fluid conduit and out of the at least one external fluid conduit into an electrochemical cell located on top of the liquid electrolyte reservoir, preferably located above the separator. In some embodiments, the electrolyte management subsystem includes an external drain conduit connected to a drain port, the external drain conduit is preferably connected to at least one fluid pump for recirculating leaked liquid electrolyte to the electrochemical cell on top of the liquid electrolyte reservoir.
[0051] Referring to the attached figure, Zn / Zn 2+ The electrochemical cell 1 comprises an upper charging section 10, a middle storage section 20 and a lower discharge section 30. The electrochemical cell 1 forms a container containing a liquid electrolyte 2, the same liquid electrolyte 2 being used in the charging and discharging operations of the cell 1.
[0052] The charging section 10 includes a plurality of charging electrodes (anodes and cathodes) 12 attached to and depending downwardly from bus bars (not shown) connected to the peripheral wall 21 of the storage section 20. The charging section 10 is covered by a cover 11 of the electrochemical cell 1. During the charging operation, the metallic zinc particles formed at the charging cathode fall through the liquid electrolyte 2 to form a solid metallic zinc particle bed 5 in the discharge section 30. During the discharge operation, the metallic zinc particle bed 5 is the discharge anode, and the solid metallic zinc is the anode material in the discharge section 30.
[0053] The storage portion 20 includes a peripheral wall 21 defining a volume having an open top and an open bottom. The lid 11 is releasably fixed to the top of the wall 21 and is sealingly supported on the top of the wall 21. The bottom of the wall 21 is releasably fixed to the discharge portion 30 and is sealingly supported on the discharge portion 30, thereby forming a container, in which a reservoir of a liquid electrolyte 2 is contained, which is contained in the battery 1, including a charging portion 10, a storage portion 20 and a discharge portion 30. The storage portion 20 can have any desired height and can be easily replaced with a storage portion of different heights. Such an arrangement illustrates how the substantially horizontal discharge cathode assembly 31 located at the bottom of the electrochemical cell 1 contributes to the modularity and reconfigurability of the electrochemical cell 1.
[0054] The discharge portion 30 includes a discharge cathode assembly 31 that forms the bottom of the electrochemical cell 1. The discharge cathode assembly 31 includes an air cathode 34 and an air cathode subassembly 31a, the air cathode subassembly 31a including a base 35 having four walls 36 and a bottom plate 37, the walls 36 serving as a frame for the air cathode 34. The bottom plate 37 covers the bottom of the frame, and the air cathode 34 covers the top of the frame. The air cathode 34, the bottom plate 37, and the walls 36 contain gaseous oxygen in a gas volume 50 that is divided into a series of channels 50a, as described below. The air cathode subassembly 31a also includes an annular flange 32a that is sealingly and removably mounted on the top of the base 35, such as by bolting the flange 32a to the base 35 through threaded bolt holes 32b in the flange 32a. The flange 32a includes an annular groove 33 inscribed in the top thereof, and the wall 21 of the storage portion 20 is sealingly supported in the annular groove 33. The discharge portion 30 further includes a separator 41 located above the air cathode 34 and covering the air cathode 34. Fig. 9 As shown, there is a gap 91 between the separator 41 and the air cathode 34. The discharge part 30 further includes a discharge anode current collector 42 located above, which contacts and covers the separator 41. The metal zinc particle bed 5 as the discharge anode and the solid metal zinc as the anode material are located on top of the discharge anode current collector 42.
[0055] The air cathode 34 includes an electrochemically active layer 38 containing a catalyst, which is laminated to the discharge cathode current collector 39 as described above. The air cathode 34 is in contact with gaseous oxygen contained in the gas volume 50 and with the separator 41. The active layer 38 is the interface region of the catalyst, liquid electrolyte 2 and gaseous oxygen. During discharge, the liquid electrolyte 2 passes through the metal zinc particle bed 5 (where the discharge anode half-cell reaction occurs), through the discharge anode current collector 42, through the separator 41, and into the air cathode 34, where the liquid electrolyte 2 penetrates into the active layer 38 through the discharge cathode current collector 39. Gaseous oxygen diffuses from the gas volume 50 into the air cathode 34, enters the active layer 38 through the discharge cathode current collector 39, and the discharge cathode half-cell reaction occurs in the interface region in the active layer 38.
[0056] The air cathode 34, separator 41 and anode current collector 42 are peaked at a peak 43 having a raised longitudinal center portion and a lower longitudinally extending outer edge, and the air cathode 34, separator 41 and anode current collector 42 intersect the longitudinal inner edge 90 of the frame at the longitudinally extending outer edge of the peak 43. The air cathode 34 is at an angle of 45° or less relative to the horizontal plane HH when used in the battery 1, so that when the air cathode 34 extends from the outer edge 90 to the peak 43, the inner angle α between the horizontal plane and the air cathode 34 (see Fig. 9 ) is 45° or less. Peak 43 helps minimize sagging of air cathode 34 and separator 41 due to the weight of the anode material while maintaining air cathode 34 in a substantially horizontal orientation. In addition, peak 43 promotes flow of liquid electrolyte 2 toward the outer edge, as described below, which facilitates electrolyte circulation.
[0057] The air cathode 34 is connected to the gas volume 50 by a plurality of laterally spaced longitudinally parallel bridge members 44 (only one is labeled, see Figure 5 and Figure 6 ) is supported in the frame of the base 35 to support the air cathode 34 thereon. The bridge 44 divides the gas volume 50 into a series of channels 50a. The bridge 44 includes through holes 45 (only one is labeled, see Figure 5 and Figure 6 ) to allow gaseous oxygen to flow laterally between channels 50a so that the concentration of gaseous oxygen remains relatively equal throughout gas volume 50. Gaseous oxygen is introduced into gas volume 50 in the form of air through an air manifold 56 in base 35, which is connected to an air port 55 protruding from base 35, the air port including an air inlet 55a and an air outlet 55b. Air is continuously introduced during discharge operation to replenish gaseous oxygen in gas volume 50 as oxygen is consumed in the discharge cathode half-cell reaction.
[0058] The discharge anode current collector 42 is connected to a discharge anode bus bar 46 housed in the base 35, which is electrically connected to a negative terminal 47 of the discharge part 30. The discharge cathode current collector 39 is connected to a discharge cathode bus bar 48 housed in the base 35, which is electrically connected to a positive terminal 49 of the discharge part 30.
[0059] The electrochemical cell 1 also includes an electrolyte management subsystem 70 for recycling the liquid electrolyte 2 in the gap 91 back to the top of the liquid electrolyte 2 reservoir in the cell 1, the liquid electrolyte 2 permeating the separator 41 and the liquid electrolyte 2 enriched by the discharge anode half-cell reaction. The electrolyte management subsystem 70 includes internal components inside the electrochemical cell 1 and in the structural elements of the charging part 10 and the discharging part 20, and also includes external components outside the electrochemical cell 1. The electrolyte management subsystem 70 is used to recirculate the liquid electrolyte 2 from the bottom of the electrochemical cell 1 to the top of the electrochemical cell 1 so that the liquid electrolyte 2 is as uniform as possible.
[0060] The electrolyte management subsystem 70 includes at least one fluid conduit that collects liquid electrolyte 2 from the gap 91 between the air cathode 34 and the separator 41 and recirculates the collected electrolyte into the liquid electrolyte above the separator 41. To this end, a plurality of fluid intake conduits 73 in the form of recirculation intake combs 72 are part of a fluid conduit manifold housed within the base 35 of the discharge cathode assembly 31 (see in particular Figure 6 , Figure 7 , Fig. 9 , Fig.12 and Fig.13 ). The fluid intake conduits 73 have respective recirculation inlets 71 located along the outer edges of the air cathode 34 and the separator 41 at the gap 91 between the air cathode 34 and the separator 41 for collecting the liquid electrolyte 2 from along the edge of the air cathode 34. The separator 41 has a perimeter that is peripherally sealed in the base 35 to prevent solid metal anode material (zinc particles) from entering the electrolyte management subsystem 70 and to cause the liquid electrolyte 2 to permeate through the separator 41 to reach the interface area of the air cathode 34. The peaks 43 encourage the liquid electrolyte 2 to flow toward the outer edges of the separator 41 and the air cathode 34, and the separator 41 has a porosity that creates a pressure differential between above and below the separator 41 to encourage the liquid electrolyte 2 to permeate more evenly through the separator 41 toward the air cathode 34 over the entire surface area of the separator 41. In this manner, liquid electrolyte 2 is drawn substantially uniformly through separator 41 across the entire exposed surface area of separator 41 and is uniformly directed toward air cathode 34 and the outer edge of separator 41 for collection by recirculation intake comb 72 .
[0061] The fluid intake conduit 73 of the recirculation intake comb 72 is connected to a series of feed conduits 74 (see Fig.13 ) fluid connection, the feed conduit 74 guides the liquid electrolyte 2 downward (flow path shown by the arrow) to the main conduit 75, which extends longitudinally along each longitudinal side of the discharge cathode assembly 31 in the base 35 to lead to a recirculation outlet 76 at one end of the base 35. A fluid guide 79 is used to guide the liquid electrolyte through the supply conduit 74. In addition, in some embodiments, since the liquid electrolyte 2 leaks into the gas volume 50 through the air cathode 34, the bottom 37 of the base 35 is provided with a discharge channel 77 (see Fig.14 ), and the bottom 37 is inclined to guide the leaked liquid electrolyte to the discharge channel 77. The discharge channel 77 guides the leaked liquid electrolyte to the discharge port 78 in one end of the base 35.
[0062] In general, it is advantageous for electrolyte management subsystem 70 to draw liquid electrolyte 2 substantially evenly from all portions of separator 41 .
[0063] Specific reference Figure 1 , Figure 2 and Figure 3 , the electrolyte management subsystem 70 also includes a pipe 80 for directing the circulating liquid electrolyte from the recirculation outlet 76 and the discharge port 78 to the front rain head 81 and the rear rain head 82 on the top of the cover 11, where the circulating liquid electrolyte can be sprayed back into the electrochemical cell 1 from the top of the liquid electrolyte 2 reservoir. The pipe 80 from the recirculation outlet 76 and the discharge port 78 is connected to a recirculation pump 83, which pumps the circulating liquid electrolyte through more pipes 80 connecting the recirculation pump 83 to a T-junction 84. At the T-junction 84, the flow of the recycled liquid electrolyte is divided, and some of the recycled liquid electrolyte is directed through another pipe to the rear rain head inlet 85 of the rear rain head 82 to be sprayed back into the electrochemical cell 1. The remaining recycled liquid electrolyte is directed through another pipe to a concentration sensor 86 for monitoring the concentration of the recycled liquid electrolyte. The remaining recycled liquid electrolyte is directed from the concentration sensor 86 through another pipe to the front rain head inlet 87 of the front rain head 81 to be sprayed back into the electrochemical cell 1. As shown in FIG. Figure 3 As shown, the rear rain showerhead 82 includes a head space 88 filled with circulating liquid electrolyte, which falls into the electrochemical cell 1 through a plurality of openings 89 at the bottom of the head space 88 .
[0064] For those skilled in the art, these novel features will become apparent after reading the specification. However, it should be understood that the scope of the claims should not be limited by the embodiments, but should be given the broadest interpretation consistent with the wording of the claims and the entire specification.
Claims
1. An electrochemical cell comprising: an anode comprising a solid anode material; a liquid electrolyte in physical contact with the solid anode material; an air cathode comprising a gaseous oxygen (O2) cathode material, wherein the air cathode is at an angle of 45 degrees or less relative to the horizontal when used in the battery; an air cathode subassembly configured to contain gaseous oxygen in a gas volume, the air cathode being sealingly mounted in the air cathode subassembly and separating the gas volume from the liquid electrolyte above the gas volume, the gaseous oxygen being able to diffuse from the gas volume into an interface region of the air cathode where the gaseous oxygen contacts the liquid electrolyte; a separator, the separator comprising an electrically insulating material, the separator separating the air cathode from the anode material, the separator being permeable to the liquid electrolyte and impermeable to the solid anode material; as well as, An electrolyte management subsystem includes at least one fluid conduit that collects the liquid electrolyte from between the air cathode and the separator and recirculates the collected electrolyte into the liquid electrolyte above the separator.
2. A battery according to claim 1, wherein the air cathode subassembly includes at least one recirculation outlet, and wherein at least one of the fluid conduits includes a plurality of internal fluid conduits in the air cathode subassembly, the plurality of internal fluid conduits being connected to the liquid electrolyte fluid between the air cathode and the separator, the plurality of internal fluid conduits having a plurality of recirculation inlets located between the air cathode and the separator, the plurality of recirculation inlets being used to collect the liquid electrolyte from along the edge of the air cathode and direct the collected liquid electrolyte to at least one of the recirculation outlets, the liquid electrolyte leaving the air cathode subassembly through the recirculation outlet.
3. A battery according to claim 2, wherein the electrolyte management subsystem includes at least one external fluid conduit and at least one fluid pump, at least one of the external fluid conduits is fluidly connected to at least one of the recirculation outlets, and at least one of the fluid pumps is operably connected to at least one of the external fluid conduits for pumping the collected liquid electrolyte through at least one of the external fluid conduits and out of at least one of the external fluid conduits into the battery above the separator.
4. The battery according to any one of claims 1 to 3, wherein the air cathode and the separator are peaked to minimize sagging of the air cathode and the separator and to promote flow of the liquid electrolyte to the outer edge of the separator.
5. The cell of claim 4 wherein said air cathode subassembly includes a plurality of bridges positioned in said gas volume to support said air cathode thereon.
6. A battery according to any one of claims 1 to 5, wherein the separator has a perimeter that is circumferentially sealed to the air cathode subassembly to prevent the solid anode material from entering the electrolyte management subsystem and so that the liquid electrolyte must permeate through the separator to reach the interface region.
7. The battery according to any one of claims 1 to 6, wherein the separator covers the air cathode to prevent anode material from directly contacting the air cathode.
8. A battery according to any one of claims 1 to 7, wherein the separator has a porosity that creates a pressure differential between above and below the separator to encourage the liquid electrolyte to more evenly penetrate the separator toward the air cathode over the entire surface area of the separator.
9. A battery according to any one of claims 1 to 8, wherein the anode comprises a bed of particles of anode material covering the separator.
10. The battery of any one of claims 1 to 9, wherein the anode material comprises zinc metal.
11. The battery of any one of claims 1 to 10, wherein the anode further comprises a conductive metal anode current collector located below and in physical contact with the anode material.
12. The battery of any one of claims 1 to 11, wherein the electrolyte comprises an aqueous solution of hydroxide ions.
13. The battery of any one of claims 1 to 12, wherein the housing comprises at least one gas port for introducing the gaseous oxygen into the gas volume.
14. The battery of any one of claims 1 to 13, wherein the air cathode subassembly is configured to sealingly support a wall thereon for containing the liquid electrolyte above the separator.
15. The battery according to any one of claims 1 to 14, wherein the battery is a charge / discharge type electrochemical cell.
16. A cathode assembly for an electrochemical cell, the cathode assembly comprising: An air cathode subassembly configured to contain a gaseous oxygen (O2) cathode material in a gas volume, the air cathode subassembly comprising: a frame defining boundaries of said gas volume; a floor defining a first side of the gas volume; at least one recirculation outlet in said air cathode assembly; and, a plurality of internal fluid conduits contained in the frame, the plurality of internal fluid conduits configured to collect liquid electrolyte from outside the gas volume to direct the collected liquid electrolyte to at least one of the recirculation outlets through which the liquid electrolyte exits the air cathode subassembly; and, An air cathode is secured to the frame to define a second side of the gas volume, the plurality of internal fluid conduits being configured to collect the liquid electrolyte along an edge of the air cathode.
17. The cathode assembly of claim 16, wherein the air cathode subassembly comprises a plurality of recirculation inlets disposed along an edge of the air cathode, the plurality of recirculation inlets collecting the liquid electrolyte from outside the gas volume.
18. A cathode assembly according to claim 16 or 17, wherein the air cathode subassembly includes a base defining the bottom plate and the frame, and the cathode assembly includes a flange removably connected to the top of the base, the flange being configured to support a wall for containing the liquid electrolyte in the electrochemical cell.
19. The cathode assembly according to any one of claims 16 to 18, wherein: The air cathode subassembly includes at least one exhaust port, and wherein the base plate is configured to direct the liquid electrolyte leaking into the gas volume to the at least one exhaust port.
20. The cathode assembly of any one of claims 16 to 19, wherein the air cathode is peaked to minimize sagging of the air cathode.
21. The cathode assembly of claim 20, wherein the air cathode subassembly comprises a plurality of bridges positioned in the gas volume for supporting the air cathode thereon.