Cartridge-type anode unit for zinc-air fuel cells

Abstract

The present invention provides a cartridge-type anode unit for obtaining a zinc-air fuel cell that is easily miniaturized and can be connected in series, with no flow loss. The cartridge-type anode unit for a zinc-air fuel cell has a main body with an opening and a separator disposed in the opening, the main body having a first connecting part configured to be detachable from a cathode unit of the zinc-air fuel cell, an anode current collecting part, and a stirring part, and the main body contains an electrolyte containing zinc particles.

Description

Technical Field

[0001] The present invention relates to a cartridge-type anode unit for a zinc-air fuel cell.

Background Art

[0002] With the recent spread and progress of mobile phones, electric vehicles, etc., there is a demand for higher capacity of the battery as their power source. Among such circumstances, a zinc-air battery utilizes oxygen in the atmosphere as a positive electrode active material at the positive electrode (air electrode), and the redox reaction of the oxygen occurs. On the other hand, at the negative electrode, the redox reaction of zinc constituting the negative electrode occurs, so that charge and discharge are possible. Therefore, it has a high energy density and is attracting attention as a high-capacity battery superior to currently widely used lithium-ion batteries.

[0003] Zinc-air batteries as primary batteries have already been commercialized and distributed, have a high energy density, and many studies have been conducted aiming at secondary batteryization of zinc-air batteries.

[0004] On the other hand, there are many problems in secondary batteryization of zinc-air batteries while maintaining the battery form. Therefore, a flow-type zinc-air battery aiming at a large-capacity stored energy has been proposed (Patent Document 1, Non-Patent Document 1). The flow-type zinc-air battery uses zinc as an active material and has a configuration in which a cell responsible for charge and discharge of a storage battery and a storage unit of a stored energy substance containing an electrolyte are independently connected by piping. The flow-type zinc-air battery can continuously supply a zinc fuel, easily obtain a stable output, and easily maximize the energy density.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Non-Patent Documents

[0006]

Non-Patent Document 1

[0007] On the other hand, because flow-type zinc-air batteries require a flow mechanism, the active material tends to accumulate within the flow mechanism pathway, leading to a decrease in the utilization efficiency of the active material, i.e., flow loss. Also, because flow-type zinc-air batteries require a flow mechanism, they are suitable for large-scale stationary systems but are difficult to miniaturize. Furthermore, in flow-type zinc-air batteries, the electrolyte is connected by fuel lines and the power generation cells conduct electricity through the fuel, so as is, the power generation cells can only be connected in parallel. To arrange them in series or a combination of series and parallel requires detailed design, such as closing the fuel lines with valves, making it difficult to increase the voltage.

[0008] Therefore, there is a need for technology to obtain a zinc-air fuel cell (zinc-air secondary battery) that has no fluid loss, is easy to miniaturize, and can be connected in series. [Means for solving the problem]

[0009] The gist of this invention is as follows: (1) A cartridge-type anode unit for a zinc-air fuel cell, comprising a main body having an opening and a separator disposed in the opening, The main body comprises a first coupling portion, an anode current collector, and a stirring portion, which are configured to be detachably attached to the cathode unit of the zinc-air fuel cell. The main body contains an electrolyte solution containing zinc particles. Cartridge-type anode unit. (2) The cartridge-type anode unit according to (1) above, wherein the stirring section is a stirring bar configured to be rotatable by a magnetic stirrer. (3) A cathode unit having a second coupling portion that is detachably configured to connect to the first coupling portion of the cartridge-type anode unit described in (1) or (2) above. (4) An electric motor equipped with the cathode unit described in (3) above. (5) An electric heater equipped with the cathode unit described in (3) above. (6) A light source comprising the cathode unit described in (3) above. (7) A vehicle equipped with the cathode unit described in (3) above. (8) An aircraft equipped with the cathode unit described in (3) above. (9) A vessel equipped with the cathode unit described in (3) above. (10) A gas device equipped with the cathode unit described in (3) above. (11) A power supply system comprising the cathode unit described in (3) above. (12) A zinc fuel regeneration apparatus having a water electrolysis tank configured to reduce the cartridge-type anode unit described in (1) or (2) above. (13) A zinc-air fuel cell comprising the cartridge-type anode unit described in (1) or (2) above and the cathode unit described in (3) above. (14) A power supply system including the zinc-air fuel cells described in (13) above, connected in series. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a cartridge-type anode unit for obtaining a zinc-air fuel cell that has no fluid loss, is easy to miniaturize, and can be connected in series. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic cross-sectional view of an example of this cartridge-type anode unit. [Figure 2] Figure 2 is a schematic cross-sectional view of this cartridge-type anode unit having a first coupling portion coupled to a second coupling portion of the cathode unit of a zinc-air fuel cell. [Figure 3] Figure 3 is a schematic cross-sectional view of the cartridge-type anode unit 1 having a first coupling portion with a male thread coupled to a second coupling portion having a female thread of the cathode unit of the zinc air fuel cell. [Figure 4] Figure 4 is a schematic cross-sectional view of the cartridge-type anode unit having a first coupling portion with a convex portion coupled to a second coupling portion having a concave portion of the cathode unit of the zinc air fuel cell. [Figure 5] Figure 5 is a schematic cross-sectional view of an insert-type cap-shaped opening / closing portion covering a position covering the separator of the cartridge-type anode unit. [Figure 6] Figure 6 is a schematic cross-sectional view of a rotary cap-shaped opening / closing portion covering a position covering the separator of the cartridge-type anode unit. [Figure 7] Figure 7 is a schematic cross-sectional view of an insert-type cap-shaped opening / closing portion covering a position covering the separator of the cartridge-type anode unit. [Figure 8] Figure 8 is a front schematic view of a slide-type cap-shaped opening / closing portion that is slide-rotatable and has an opening. [Figure 9] Figure 9 is a schematic cross-sectional view when the zinc air fuel cell formed by coupling the cartridge-type anode unit and the cathode unit is discharging. [Figure 10] Figure 10 is a schematic cross-sectional view of the cartridge-type anode unit 1 during the regeneration process (charging) in the zinc fuel regeneration device. [Figure 11] Figure 11 is a graph showing the air electrode potential and discharge power density with respect to the discharge current density of the zinc air fuel cell configured by connecting the charged cartridge-type anode unit to the cathode unit.

Embodiments for Carrying Out the Invention

[0012] This disclosure relates to a cartridge-type anode unit for a zinc-air fuel cell, having a main body having an opening and a separator disposed in the opening, wherein the main body comprises a first coupling portion, an anode current collector portion, and a stirring portion configured to be detachably attached to the cathode unit of the zinc-air fuel cell, and the main body contains an electrolyte solution containing zinc particles.

[0013] According to the cartridge-type anode (negative electrode) unit of this disclosure (hereinafter also referred to as this cartridge-type anode unit), a zinc-air fuel cell can be obtained that is easy to miniaturize, can be connected in parallel or in series, and does not suffer flow loss due to the accumulation of active material in the flow mechanism path.

[0014] Conventional rechargeable batteries are connected to motors or other devices during use, and charged by connecting to a charger, or by directly supplying power while connected to a motor or other device. This results in a problem of long charging times.

[0015] In contrast, this cartridge-type anode unit can be used as a cartridge, and is connected to a zinc-air fuel cell equipped with a cathode unit (air electrode unit) for use (discharge). After use, it can be removed from the cathode unit, and the zinc active material can be reduced and recharged. Furthermore, because this cartridge-type anode unit can be used as a cartridge, there is no need to disassemble the anode unit to regenerate the zinc oxide. Another charged cartridge-type anode unit can be connected to the cathode unit of a zinc-air fuel cell from which this cartridge-type anode unit has been removed, so there is no charging time. This cartridge-type anode unit can be used in electric motors and the like by being replaced in this way.

[0016] Furthermore, this cartridge-type anode unit can be delivered (transported) as a standalone unit. Therefore, this cartridge-type anode unit has a very high energy density based on the volume of the cartridge unit, and a very high energy density relative to the delivery and storage costs. This cartridge-type anode unit preferably has an energy density of 30 Wh / L to 7000 Wh / L or 10 to 950 Wh / kg.

[0017] This cartridge-type anode unit is easily miniaturized and allows for the handling of zinc fuel in cartridge units, making it suitable for use in small-scale power supply systems. It is particularly suitable for use in electric motors, electric heaters, or light sources, and can be easily mounted on vehicles, aircraft, ships, and electrical equipment. Furthermore, this cartridge-type anode unit facilitates the series connection of zinc-air fuel cells to which it is coupled, making it suitable for medium-sized or large-sized stationary power supply systems.

[0018] Furthermore, this cartridge-type anode unit allows for the handling of zinc fuel in cartridge units, enabling the recovery of used waste fuel in cartridge units and subsequent reprocessing (recycling).

[0019] Figure 1 shows a schematic cross-sectional view of an example of this cartridge-type anode unit. The cartridge-type anode unit 1 has a main body 10 having an opening 11 and a separator 12 positioned in the opening 11.

[0020] The main body 10 comprises a first coupling part 13, an anode current collector part 14, and a stirring part 16, which are detachably configured to be attached to the cathode unit of the zinc-air fuel cell, and contains an electrolyte 15 containing zinc particles inside the main body 10.

[0021] The main body 10 is a container that holds the fuel, which is an electrolyte containing zinc particles, inside. The material of the main body 10 is not particularly limited as long as it can hold the fuel inside, but it is preferably made of resin, metal, or a combination thereof. The resin is preferably a thermoplastic resin, and more preferably polypropylene. The metal is preferably stainless steel. The main body 10 may be based on, for example, a polypropylene vial, or it may be a stainless steel metal container. When the stirring unit, which will be described later, is operated by a wireless signal from outside the main body 10, it is preferable that at least a part of the main body 10 is made of a resin that transmits wireless signals.

[0022] The main body 10 includes an anode current collector 14. The anode current collector 14 can be a current collector extending from the inside to the outside of the main body 10, as illustrated in Figure 1. If at least a part of the main body 10 is made of a conductive metal, the metal part may function as the anode current collector 14. When the cartridge-type anode unit 1 is connected to the cathode unit, the anode current collector 14 may extend so as to be electrically connected to an anode contact provided on the cathode unit side via a first coupling portion.

[0023] The material of the anode current collector 14 is not particularly limited and can be any material that has been conventionally used as a current collector for secondary batteries. For example, it can be a conductive metal plate, metal rod, etc. made of copper, SUS, nickel, etc., or a plate, rod, etc. made of carbon material.

[0024] The main body 10 is provided with an opening 11 for arranging the separator 12. The size of the opening 11 should be such that it does not substantially impede the battery characteristics as internal resistance when the cartridge-type anode unit 1 is coupled with the cathode unit described later to operate as an air-zinc fuel cell. The size of the opening 11 may be the same as or less than the cross-sectional area perpendicular to the longitudinal direction connecting the cartridge-type anode unit 1 and the cathode unit, preferably 50 to 100%, more preferably 60 to 90%, and even more preferably 70 to 80% of the said cross-sectional area.

[0025] The separator 12 can be a conventionally used separator, such as a polymer nonwoven fabric like a polypropylene nonwoven fabric or a polyphenylene sulfide nonwoven fabric, a microporous film made of an olefin resin like polyethylene or polypropylene, or a combination thereof. The separator 12 can be impregnated with an electrolyte to function as an ion conductor. The separator 12 can allow only ions to pass through without allowing the zinc active material to leak out. The separator 12 can also be impregnated with an electrolyte to form an electrolyte layer.

[0026] The separator 12 preferably has a thickness of 10 to 500 μm. The main body 10 having a separator of the aforementioned preferred thickness makes it easier to suppress the outflow of electrolyte during storage or transport while suppressing a substantial increase in internal resistance when the cartridge-type anode unit 1 is connected to the cathode unit to constitute a zinc-air fuel cell.

[0027] The separator 12 only needs to be physically stable in the electrolyte and have ionic conductivity, preferably having an ionic conductivity of 1 mS / cm or more, more preferably 10 mS / cm or more. Having such a desirable ionic conductivity in the separator 12 allows the zinc-air fuel cell to which the cartridge-type anode unit 1 is connected to exhibit good battery characteristics, and also enables good reduction processing (charging) of the cartridge-type anode unit 1.

[0028] The separator 12 can have a Gurley permeability of, for example, 1 sec / 100 mL to 10,000 sec / 100 mL or more. Preferably, the separator 12 has a Gurley permeability of 3 to 2,000 sec / 100 mL, more preferably 5 to 1,000 sec / 100 mL, even more preferably 7 to 500 sec / 100 mL, and even more preferably 10 to 250 sec / 100 mL. By having a separator with the above-mentioned preferred permeability in the main body 10, it becomes easier to suppress the outflow of electrolyte during storage or transport while suppressing a substantial increase in internal resistance when the cartridge-type anode unit 1 is connected to the cathode unit to constitute a zinc-air fuel cell. The permeability can be measured with a Gurley-type permeability tester (Gurley densometer).

[0029] The main body 10 has a first coupling portion 13 that is detachably configured to attach to the cathode unit of the zinc-air fuel cell. The presence of this first coupling portion 13 in the main body 10 allows the cartridge-type anode unit 1 to be used in a cartridge configuration. As illustrated in Figure 1, the main body 10 may have the first coupling portion 13 on its outer circumferential surface near the separator 12, on its bottom near the separator 12, or both.

[0030] As illustrated in Figure 2, the first coupling portion 13 can be inserted into or fitted into the second coupling portion 23 of the cathode unit 20 of the zinc-air fuel cell so that the cartridge-type anode unit 1 and the cathode unit 20 are electrically coupled. Figure 2 is a schematic cross-sectional view of the cartridge-type anode unit 1 having the first coupling portion 13 coupled to the second coupling portion 23 of the cathode unit 20 of the zinc-air fuel cell. The second coupling portion 23 may have a concave shape that can accept the surface shape of the first coupling portion 13. The cartridge-type anode unit 1 and the cathode unit 20 can be electrically coupled via the separator 12.

[0031] As illustrated in Figure 3, the first coupling portion 13 may have a male screw 131 on its surface. In this case, the second coupling portion 23 may have a female screw that can be screwed onto the male screw 131. Figure 3 is a schematic cross-sectional view of a cartridge-type anode unit 1 having a first coupling portion 13 with a male screw 131 connected to a second coupling portion 23 with a female screw of a zinc-air fuel cell cathode unit 20.

[0032] The first coupling part 13 can be coupled to the second coupling part 23 by relatively rotating the main body 10 of the cartridge-type anode unit 1 so that the male thread 131 of the first coupling part 13 is screwed into the female thread of the second coupling part 23. The first coupling part 13 may have a female thread and the second coupling part 23 may have a male thread.

[0033] As illustrated in Figure 4, the first coupling portion 13 may have a protrusion 132 on its surface. In this case, the second coupling portion 23 may have a recess that can be fitted into the protrusion 132. Figure 4 is a schematic cross-sectional view of a cartridge-type anode unit 1 having a first coupling portion 13 having a protrusion 132 coupled to a second coupling portion 23 having a recess in the cathode unit 20 of a zinc-air fuel cell.

[0034] The first coupling portion 13 can be coupled to the second coupling portion 23 by pushing the main body portion 10 of the cartridge-type anode unit 1 so that the protrusion 132 fits into the recess of the second coupling portion 23. The number of protrusions 132 and recesses can be one or more. The first coupling portion 13 may have a recess and the second coupling portion 23 may have a protrusion.

[0035] The main body 10 may have an opening / closing section configured to open and close at a position covering the separator 12. The opening / closing section can be closed when storing or transporting the cartridge-type anode unit 1, and opened when connecting to the cathode unit of a zinc-air fuel cell or a zinc fuel regeneration device. By providing an opening / closing section in the main body 10, it is possible to suppress the leakage or evaporation of electrolyte from the separator during storage and transport, even when using a separator with low air permeability.

[0036] The opening / closing part can be provided at a position that contacts the first coupling part 13 of the main body part 10. When the opening / closing part is closed, it may be in contact with the separator 12, or it may be adjacent with a gap, but preferably the opening / closing part is in contact with the separator 12. By having the opening / closing part in contact with the separator 12 when the opening / closing part is closed, the outflow and evaporation of the electrolyte can be further suppressed.

[0037] The opening / closing section is configured to be openable and closable by any method, such as insertion, rotation, or sliding. When the opening / closing section is closed, it may be closed by gravity, and preferably it is closed by fitting. When the opening / closing section 30 is opened, it may be separated from the main body 10, or it may be connected to the main body 10 with a band, string, chain, etc., to prevent it from falling off.

[0038] Figure 5 shows a schematic cross-sectional view of an insertable cap-shaped opening / closing part 30 that is placed over the separator 12 of the cartridge-type anode unit 1. By making the outer circumference dimensions of the first connecting part 13 and the inner circumference dimensions of the opening / closing part 30 substantially the same, the opening / closing part 30 can be fitted onto the main body part 10.

[0039] If the main body 10 has a male screw 131 on the surface of the first joint 13 as illustrated in Figure 3, a cap-shaped opening / closing part 30 having a female screw that can be screwed onto the male screw 131 can be placed over it, as shown in Figure 6. Figure 6 is a schematic cross-sectional view of a rotatable cap-shaped opening / closing part 30 placed over the separator 12 of the cartridge-type anode unit 1.

[0040] By rotating the opening / closing part 30 in a relative tightening direction so that the female thread of the cap-shaped opening / closing part 30 engages with the male thread 131 of the first connecting part 13, the separator 12 can be covered with the opening / closing part 30. To open the opening / closing part, it can be removed from the main body 10 by rotating the opening / closing part 30 in a loosening direction. The first connecting part 13 may have a female thread, and the cap-shaped opening / closing part 30 may have a male thread. If the opening / closing part is a rotating cap shape with a male thread and a female thread that engage, the opening / closing part 30 can be firmly fitted to the main body 10, and the opening / closing part can be more effectively prevented from falling off when it is closed. Also, because it is rotating, it does not require much force to open the opening / closing part, and there is less wear on the male and female threads that are the fitting members.

[0041] If the main body 10 has a protrusion 132 on the surface of the first connecting portion 13 as illustrated in Figure 4, a cap-shaped opening / closing portion 30 having a recess that can be fitted onto the protrusion 132 can be placed over it, as shown in Figure 7. Figure 7 is a schematic cross-sectional view of an insertable cap-shaped opening / closing portion 30 placed over the separator 12 of the cartridge-type anode unit 1.

[0042] By pushing the main body 10 of the cartridge-type anode unit 1 so that the recess of the cap-shaped opening / closing part 30 fits into the protrusion 132 of the first connecting part 13, the separator 12 can be covered with the opening / closing part 30. The first connecting part 13 may have a recess, and the cap-shaped opening / closing part 30 may have a protrusion. If the opening / closing part is an insertable cap shape in which the protrusion and recess fit together, the opening / closing part 30 can be firmly fitted into the main body 10, and the opening / closing part can be more effectively prevented from falling off when it is closed. Also, because it is an insertable type, it is easy to connect to the main body with a band or the like, and it is easier to prevent it from falling off the main body 10 when it is opened.

[0043] If the separator 12 is located at the end of the main body 10 rather than in the center, an opening / closing part 30 having an opening 301 and slidable and rotatable parallel to the surface of the separator 12 can be placed over the separator 12. Figure 8 shows a schematic front view of a sliding, cap-shaped opening / closing part 30 having an opening 301. The arrows indicate the direction in which the opening / closing part 30 can slide and rotate. The sliding, cap-shaped opening / closing part 30 having an opening 301, which is placed over the separator 12, can be rotated to fix it in a position where the separator 12 is closed during storage and transport, or in a position where the separator 12 is exposed.

[0044] The main body 10 of the cartridge-type anode unit 1 is equipped with a stirring section. The stirring section can stir the electrolyte contained in the main body 10. During charging and discharging, zinc particles in the electrolyte may coarseen and dendrites may grow, but stirring the electrolyte with the stirring section can prevent the coarsening of zinc particles and the growth of dendrites. Although not bound by theory, zinc coarsening may occur as zinc undergoes repeated oxidation and reduction in the electrolyte, and precipitated zinc oxide may be contained in the coarse particles. As it tries to become a lower energy state as a crystal, zinc that is formed as a dendritic during charging may coarseen when it is oxidized and reduced at the solid-liquid interface, reducing its surface area.

[0045] The stirring unit may be configured to perform stirring operations using electrical or magnetic energy supplied from outside the main body 10. The stirring unit may also be configured to allow adjustment of the stirring intensity by varying the strength of the energy supplied from the outside. The stirring unit may also be configured to allow control of the stirring operation using wireless or wired signals from outside the main body 10. The stirring unit provides a mechanical stirring action to the electrolyte and can be a stirring bar that rotates using magnetic force, an ultrasonic stirrer, a screw-type stirrer, or a mechanism that provides stirring by rotating a cartridge-type anode unit 1 which has fixed blades inside the main body 10.

[0046] The stirring unit is preferably positioned between the anode current collector 14 and the separator 12, and more preferably in close proximity to or in contact with the surface of the separator 12, at least during the reduction process (charging). Figure 1 schematically shows an configuration in which the stirring unit 16 is positioned in contact with the surface of the separator 12. When reducing zinc oxide in the electrolyte to zinc, zinc dendrites may grow toward the counter electrode (cathode). However, by positioning the stirring unit 16 preferably between the anode current collector 14 and the separator 12, and more preferably in close proximity to or in contact with the surface of the separator 12, the growth of dendrites stops in the vicinity of the stirring unit 16, thereby suppressing the dendrites from coming out of the separator 12. Since the stirring by the stirring unit 16 is mechanical stirring, the effect of suppressing dendrite growth is much greater compared to the chemical action of conventionally used complexing agents. The complexing agent diffuses to the cathode (positive electrode) side during the dissolution stage in the electrolyte, and undergoes oxidative degradation during the oxygen evolution reaction at the cathode, making it difficult to apply to long-term regeneration and utilization cycles.

[0047] The stirring section 16 is preferably a stirring bar of a magnetic stirrer. The stirring bar can rotate using the magnetic force generated by the magnetic stirrer. The stirring bar can be rotated by the magnetic force applied from a magnetic stirrer located outside the main body 10, and its position within the main body 10 can be easily adjusted. For example, a magnetic stirrer can be placed opposite the stirring section 16, with a separator 12 on the outside of the main body 10 in between. A cartridge-type anode unit 1 can be placed in the central region of the magnetic stirrer with the separator 12 facing downwards, and the stirring bar can be positioned and rotated by magnetic force in the center of the separator 12. The stirring bar is also preferable from the viewpoint of cost and maintenance because it does not require complex mechanical structures or wiring inside the main body 10.

[0048] The electrolyte held inside the main body 10 can be any electrolyte commonly used in secondary batteries, and is not particularly limited; it can be an aqueous electrolyte, an organic electrolyte, or a combination thereof. The electrolyte only needs to be fluid and can be a liquid electrolyte, a gel electrolyte, a polymer electrolyte, or a combination thereof. From a safety standpoint, the electrolyte is preferably an aqueous electrolyte, or an electrolyte mainly composed of an aqueous electrolyte with an organic electrolyte or a mixture of organic electrolytes.

[0049] Examples of organic electrolytes include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, dimethoxymethane, diethoxymethane, dimethoxyethane, tetrahydrofuran, methyltetrahydrofuran, diethoxyethane, dimethyl sulfoxide, sulfolane, acetonitrile, benzonitrile, ionic liquids, fluorine-containing carbonates, fluorine-containing ethers, polyethylene glycols, and fluorine-containing polyethylene glycols. One or more organic electrolytes can be used.

[0050] Examples of aqueous electrolytes include aqueous potassium hydroxide solution, aqueous sodium hydroxide solution, aqueous lithium hydroxide solution, aqueous zinc sulfate solution, aqueous zinc nitrate solution, aqueous zinc phosphate solution, and aqueous zinc acetate solution. Among these, alkaline electrolytes such as aqueous potassium hydroxide solution, aqueous sodium hydroxide solution, and aqueous lithium hydroxide solution are preferred. One or more of the above aqueous electrolytes can be used. The aqueous electrolyte may also contain the above organic solvent-based electrolyte.

[0051] The concentration of the electrolyte in the electrolyte solution is not particularly limited and can be any concentration. The electrolyte solution may also be weakly acidic, neutral, or alkaline, and the pH of the electrolyte solution is preferably 6 to 14, more preferably 6 to 12, and even more preferably 7 to 10.

[0052] The electrolyte contains zinc particles as the negative electrode active material. The zinc particles include metallic zinc particles, zinc compound particles, or combinations thereof. The zinc particles have an average particle size (diameter) preferably in the range of 1 to 500 μm, more preferably 5 nm to 200 μm, even more preferably 10 nm to 100 μm, and even more preferably 10 nm to 60 μm. In addition to zinc particles, the electrolyte may further contain particles of other metals or other metallic compounds such as magnesium particles, aluminum particles, iron particles, and copper particles. The above average particle size can be measured as D50 using a particle size distribution analyzer.

[0053] The electrolyte may further contain a catalyst and / or a complexing agent. The catalyst contained in the electrolyte can be a conventionally used catalyst, preferably carbon particles. The carbon particles can be graphite, carbon fiber, carbon black, carbon nanoparticles, etc. The ratio of carbon particles to zinc particles is preferably in the range of 2.5 to 10% by mass. The proportion of electrolyte in the zinc-containing electrolyte is preferably in the range of 50 to 80% by volume.

[0054] The complexing agent can be any complexing agent conventionally used to suppress dendrite formation at the negative electrode, such as ethylenediaminetetraacetic acid (EDTA), citric acid, or ammonium hydroxide.

[0055] The separator 12 can be impregnated with an electrolyte to function as an electrolyte layer. The electrolyte layer 24 may also contain a nonwoven fabric impregnated with an electrolyte. The electrolyte layer exhibits ionic conductivity between the cathode and the anode. The nonwoven fabric contained in the electrolyte layer 24 may be the same as the nonwoven fabric that can be used in the separator 12.

[0056] The main body 10 of the cartridge-type anode unit 1 can be any shape, such as a cylindrical shape, a rectangular parallelepiped shape, or a combination thereof, and is preferably cylindrical. The cylindrical shape of the cartridge allows it to be moved by rolling from top to bottom. By setting the cylindrical cartridge in a cassette that can be moved by gravity from top to bottom, such as in a beverage vending machine, the charged cartridge-type anode units 1 can be sequentially fed and connected to the cathode unit of a zinc-air fuel cell from which the used cartridge-type anode units 1 have been removed.

[0057] This disclosure also relates to a cathode unit (air electrode unit) having a first coupling portion and a second coupling portion detachably configured to the cartridge-type anode unit 1 described above. A zinc-air fuel cell can be constructed by coupling the cartridge-type anode unit 1 to this cathode unit. A used cartridge-type anode unit 1 can be removed from this cathode unit, and a recharged (charged) cartridge-type anode unit 1 can be attached to this cathode unit for use as a zinc-air fuel cell. The used cartridge-type anode unit 1 can be subjected to recharge treatment.

[0058] Figure 2 shows a schematic cross-sectional view of a zinc-air fuel cell constructed by connecting a cartridge-type anode unit 1 to a cathode unit 20. The housing of the cathode unit 20 can be made of a resin such as acrylic. The material of the second coupling part 23 is not particularly limited as long as it can be inserted into or fitted with the first coupling part 13, but it can be made of a resin such as acrylic.

[0059] The cathode unit 20 is not particularly limited as long as it includes a second coupling portion 23 and functions as an air electrode, and may have a conventional air electrode configuration. The cathode unit 20 may also include an air electrode layer 22, an electrolyte layer 24, and a cathode current collector.

[0060] The air electrode layer 22 may have a configuration in which a water-repellent layer and a catalyst layer are held by a metal mesh. By pressing the water-repellent layer and the catalyst layer onto the metal mesh, the water-repellent layer and the catalyst layer can be held by the cathode current collector such as the metal mesh. The water-repellent layer can be a conventionally used water-repellent layer, for example, a porous film of polytetrafluoroethylene (PTFE). The catalyst layer can be a conventionally used catalyst layer, for example, a mixed layer of carbon and catalyst.

[0061] The catalyst contained in the catalyst layer is not particularly limited as long as it is a material conventionally used for air electrodes, and can be conductive carbon such as Ketjenblack, acetylene black, Denka black, carbon nanotubes, and fullerenes, as well as metals, metal oxides, metal hydroxides, metal sulfides, etc., and one or more of these can be used.

[0062] The mass percentage of catalyst contained in the catalyst layer is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, out of 100% by mass of the catalyst layer. Furthermore, the mass percentage of catalyst contained in the catalyst layer is preferably 98% by mass or less, and more preferably 95% by mass or less. When the proportion of catalyst is within the above preferred range, the function of the air electrode can be made more sufficient.

[0063] The catalyst layer may further contain a binder. The binder is not particularly limited as long as it is a material conventionally used for air electrodes, and may be thermoplastic or thermosetting. Examples include halogen atom-containing polymers such as polyvinylidene fluoride and polytetrafluoroethylene, hydrocarbon moiety-containing polymers such as polyolefins, aromatic group-containing polymers such as polystyrene; ether group-containing polymers such as alkylene glycols; hydroxyl group-containing polymers such as polyvinyl alcohol; amide bond-containing polymers such as polyamides and polyacrylamides; imide group-containing polymers such as polymaleimide; carboxyl group-containing polymers such as poly(meth)acrylic acid; carboxylic acid base-containing polymers such as poly(meth)acrylates; sulfonate moiety-containing polymers; quaternary ammonium salts and quaternary phosphonium salt-containing polymers; ion-exchange polymers; natural rubber; artificial rubber such as styrene-butadiene rubber (SBR); sugars such as hydroxyalkylcellulose (e.g., hydroxyethylcellulose) and carboxymethylcellulose; amino group-containing polymers such as polyethyleneimine; and polyurethane.

[0064] The mass percentage of the binder in the catalyst layer is preferably 0.1 to 10% by mass, more preferably 0.5 to 8% by mass, and even more preferably 1 to 5% by mass.

[0065] The thickness of the catalyst layer is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more.

[0066] The air electrode layer 22 may further comprise a gas diffusion layer (GDL). The GDL may be able to take in air from the outside and may comprise layers of carbon particles and platinum particles accompanied by several hydrophobic agents such as Teflon®. A separation membrane may be provided between the catalyst layer and the adjacent electrolyte layer 24.

[0067] The cathode current collector can be made from any material conventionally used as a current collector, such as carbon paper, porous structures like metal mesh, mesh-like structures, fibers, or nonwoven fabrics. For example, a metal mesh made from SUS, nickel, aluminum, iron, or titanium can be used. A metal foil with oxygen supply holes can also be used as the cathode current collector.

[0068] This cathode unit can be installed in machines that require electricity. Preferably, this cathode unit can be installed in electric motors, electric heaters, or light sources. Examples of electric motors include belt conveyors, chainsaws, cranes, power shovels, pumps, electric toys (including electric skateboards), polishers, electric lawnmowers, etc. Examples of electric heaters include heaters, air conditioners (including cooling and dehumidifying), etc. Examples of light sources include flashlights, outdoor lighting devices for construction and other purposes, lasers, camping lights, tent lights, underground shelter lights, etc.

[0069] This cathode unit can also preferably be installed in vehicles, aircraft, ships, electrical equipment, or power supply systems. Examples of vehicles include electric passenger cars (including hybrids), buses, trucks, electric motor motorcycles, wheelchairs, tractors, agricultural machinery, snowmobiles, and trains. This cathode unit can also be used as an auxiliary power source for vehicles, a replacement power source for lead-acid batteries, etc. For domestic vehicles, the cathode unit is preferably located on the left side of the vehicle, and for US vehicles, it is preferably located on the right side of the vehicle, with an opening for inserting and removing the cartridge-type anode unit. Examples of aircraft include general jet aircraft (passenger and cargo planes), electric propeller aircraft (passenger and cargo planes), drones, satellites, and space stations. Examples of ships include recreational motorboats, jet skis, submarines, and general vessels.

[0070] Electrical equipment can be any electrical equipment that is commonly used, and examples include communication equipment, household electrical appliances, measuring instruments, air purifiers, devices for collecting water from the air, robots, and external power supplies for personal computers.

[0071] Examples of power supply systems include emergency power supplies for buildings or hospitals, stationary power supplies, and other applications such as storage of commercial and industrial power, storage of residential solar panels, storage for microgrid construction, storage for peaking plants, backup power for renewable energy, storage for renewable energy grid integration, seasonal energy storage, and storage for grid services (especially for demand response, ancillary services, governor-free operation, frequency regulation, etc.). Portable power supplies may also be used.

[0072] In vehicles, aircraft, ships, electrical equipment, or power supply systems, this cathode unit may be connected in series, parallel, or both series and parallel.

[0073] This disclosure also relates to a zinc fuel regeneration apparatus having a water electrolysis tank configured to reduce the cartridge-type anode unit 1 described above.

[0074] During discharge (power generation) of a zinc-air fuel cell, which consists of a cartridge-type anode unit 1 and a cathode unit 20, the zinc active material, which is the fuel, is oxidized within the main body 10. Figure 9 shows a schematic cross-sectional view of a zinc-air fuel cell, which consists of a cartridge-type anode unit 1 and a cathode unit 20, during discharge. As shown in Figure 9, during discharge, the zinc contained in the electrolyte 15 within the main body 10 is oxidized, and an electrolyte 18 containing zinc oxide is generated from the cathode unit side.

[0075] The waste fuel containing the generated zinc oxide is recovered while still mounted in the cartridge-type anode unit 1. The zinc oxide in the recovered waste fuel is electrochemically reduced to zinc in a zinc fuel regeneration device and can be reused as fuel. During the electrochemical reaction in the zinc-air fuel cell or zinc fuel regeneration device, the zinc may become coarse, but this coarsening and dendrite growth can be suppressed by stirring the electrolyte in the stirring section.

[0076] Figure 10 shows a schematic cross-sectional view of the cartridge-type anode unit 1 during regeneration (charging) in the zinc fuel regeneration device 40. During the regeneration process (charging), the zinc oxide contained in the electrolyte 18 inside the main body 10 is reduced to zinc from the vicinity of the anode current collector 14 extending from the inside to the outside of the main body 10, generating an electrolyte 15 containing zinc.

[0077] The water electrolysis tank of the zinc fuel regeneration device 40 may have a container 41 configured to hold an aqueous solution 43 and electrodes 42 for performing electrolysis of water. The material of the container 41 is not particularly limited as long as it can hold the aqueous solution 43, and may be a resin container such as polypropylene. The separator 12 side of the used cartridge-type anode unit 1 is immersed in the aqueous solution 43, and electrolysis of the water is performed by the electrodes 42 placed in the aqueous solution 43, and the generated hydrogen can be used to reduce zinc oxide to zinc.

[0078] The zinc fuel regeneration device 40 has a holding portion that can hold the cartridge-type anode unit 1, and preferably the container 41 has a holding portion that can hold the cartridge-type anode unit 1.

[0079] The structure of the holding part is not particularly limited as long as it can hold the cartridge-type anode unit 1. It may have a structure that holds the cartridge-type anode unit 1 horizontally so that it does not tip over when supported at the bottom of the container 41 by gravity, or it may have a structure that holds the cartridge-type anode unit 1 both horizontally and vertically. For example, the container 41 may have a fixing jig having a hole with a diameter substantially the same as or slightly larger than the outer diameter of the cartridge-type anode unit 1 to hold the cartridge-type anode unit 1 horizontally. Alternatively, the container 41 may have a fixing jig having a hole with an outer diameter substantially the same as or slightly larger than the outer diameter of the cartridge-type anode unit 1 and a tightening mechanism for the hole to hold the cartridge-type anode unit 1 horizontally and vertically. The zinc fuel regeneration device may have a third coupling part that is detachably configured from the first coupling part. The configuration of the third coupling part is not limited as long as ions can be conducted through the separator 12, and it may have a configuration similar to that of the second coupling part described above.

[0080] Preferably, the cartridge-type anode unit 1 is placed in the aqueous solution 43 of the container 41 such that there is a gap between the separator 12 and the bottom surface of the container 41. This gap may be formed by placing a nonwoven fabric or the like at the bottom of the container 41. Having a gap between the separator 12 and the container 41 ensures more reliable conductivity between the inside and outside of the main body 10.

[0081] The zinc fuel regeneration device 40 preferably includes a magnetic stirrer 44 that generates a magnetic force to rotate the stirring section 16, which is an agitator within the main body 10. The magnetic stirrer 44 may include a magnet and a motor with a variable rotational speed for rotating the magnet. The cathode unit may also include a magnetic stirrer. The magnetic stirrer 44 allows the stirring section 16 to rotate as shown by the arrow in Figure 10, thereby stirring the electrolyte within the main body 10.

[0082] This disclosure also relates to a zinc-air fuel cell comprising the cartridge-type anode unit 1 and the cathode unit 20 described above. This zinc-air fuel cell contains an electrolyte containing zinc active material as zinc fuel within the main body 10. The cartridge-type anode unit 1 can be connected to the second coupling portion 23 of the cathode unit 20 to constitute this zinc-air fuel cell, which can then be used for discharge.

[0083] Multiple zinc-air fuel cells can be used in series, parallel, or both series and parallel connections. In particular, in power supply systems, which are relatively large-scale stationary facilities for temporarily storing electricity, connecting these zinc-air fuel cells in series allows for output at relatively high voltages. [Examples]

[0084] (Example 1) (Fabrication of cartridge-type anode units) A polypropylene vial (25 mm in diameter, 5 cm in height) was used as the main body 10, and a Zn-plated SUS nail was attached to the bottom of the vial as the anode current collector. 10 g of metallic zinc powder (particle size 75-200 μm) was placed inside the vial. Next, a magnetic stirrer coated with polytetrafluoroethylene (PTFE) was placed inside as the stirring section, and 20 g of a 3 M potassium hydroxide aqueous solution was added as the electrolyte. To ensure ion conduction and prevent the discharge of zinc powder, an opening was made in the lid of the vial, and the opening was sealed with a separator made of nonwoven fabric (100 μm thick, Gurley value 20 sec / 100 mL). The lid with the nonwoven fabric covering the opening was attached to the vial, and a cartridge-type anode unit having a first coupling section with a diameter of 25 mm, schematically shown in Figure 1, was fabricated.

[0085] (Fabrication of the cathode unit) Ketjenbrak:PTFE aqueous dispersion (solid content concentration Nv60%):water was mixed in a mass ratio of 10:1:2. The mixture was placed in a polyethylene bag and rolled in a roll press machine adjusted to a gap of 0.5 mm between the rolls to obtain a flat paste. The obtained flat paste was rolled onto a Ni-plated SUS mesh to be used as a current collector to form an integrated layer. A PTFE water-repellent film (thickness 100 μm, Gurley value 18 sec / 100 mL) was then rolled onto one side of the paste to create an air electrode layer (oxygen reduction electrode).

[0086] An acrylic resin housing was prepared, having a second joint with an inner diameter of 25 mm configured to accommodate a cartridge-type anode unit. A nonwoven fabric (1 mm thick) was placed adjacent to the second joint, and 3 g of 3M potassium hydroxide aqueous solution was introduced so that it would soak into the nonwoven fabric.

[0087] A cathode unit, schematically shown in Figure 2, was fabricated by attaching the fabricated oxygen reduction electrode to the end face of the acrylic resin housing opposite the second joint.

[0088] (Fabrication of zinc-air fuel cells) A zinc-air fuel cell, schematically shown in Figure 2, was fabricated by fitting the first coupling portion of a fabricated cartridge-type anode unit to the second coupling portion of a fabricated cathode unit, so that the nonwoven fabric attached to the vial lid of the cartridge-type anode unit and the nonwoven fabric placed on the cathode unit were in contact. During the above fitting, the electrolyte impregnated in each nonwoven fabric mixed together, forming an ion conduction path and enabling discharge.

[0089] (Measurement of electrical characteristics) A discharge test was conducted using the cartridge-type anode unit of the fabricated zinc-air fuel cell as the negative electrode and the oxygen reduction electrode of the cathode unit as the positive electrode. The discharge test was performed using a charge / discharge tester HJ1001SD8 manufactured by Hokuto Denko Co., Ltd., with a discharge current of 0.1 mA / cm². 2 ~200mA / cm 2The discharge voltage was measured while varying the current, and the discharge power at each discharge current was calculated.

[0090] Figure 11 shows a graph representing the air electrode potential and discharge power density as a function of the discharge current density of the fabricated zinc-air fuel cell. Approximately 100 mA / cm² 2 We were able to increase the current density to this level. Starting with just under 1.4V in an open circuit and gradually increasing the current density, the current density reached approximately 100mA / cm². 2 The electrical characteristics that resulted in the maximum discharge power density were confirmed.

[0091] (Example 2) A cartridge-type anode unit was prepared in the same manner as in Example 1, except that 1 g of metallic zinc powder was placed in a vial. A zinc-air fuel cell was then prepared by combining it with a cathode unit in the same manner as in Example 1. The prepared zinc-air fuel cell had a theoretical capacity of 820 mAh / g and an output of 10 mA / cm². 2 It showed a discharge capacity of 750 mAh / g at a discharge current.

[0092] After discharge, the cartridge-type anode unit was removed from the zinc-air fuel cell and introduced into a potassium hydroxide aqueous solution in a container of a zinc fuel regeneration device equipped with a magnetic stirrer, as schematically shown in Figure 10. While stirring the electrolyte by rotating the agitator inside the main body of the cartridge-type anode unit with the magnetic stirrer, electrolysis of water was performed using electrodes, maintaining the same discharge rate of 10 mA / cm². 2 The zinc oxide generated inside the main unit was regenerated by performing a charging reaction at the specified current rate. This regeneration process yielded 748 mAh / g of zinc. When the regenerated cartridge-type anode unit was reconnected to the cathode unit of the zinc-air fuel cell and discharged, a discharge capacity of 720 mAh / g was confirmed. [Explanation of Symbols]

[0093] 1. Cartridge-type anode unit 10 Main body 11 Opening of the main body 12 Separators 13 First joint 131 Male screw 132 Convex part 14 Anode current collector 15. Electrolyte containing zinc 16 Stirring section 18. Electrolyte containing zinc oxide 20. Cathode unit for zinc-air fuel cell 22. Polar air layer 23 Second joint 24 Electrolyte layer 30 Opening / Closing Section 301 Opening of the opening / closing section 40. Zinc fuel regeneration device 41 Container 42 electrodes 43 Aqueous solution 44 Magnetic Stirrer

Claims

1. A cartridge-type anode unit for a zinc-air fuel cell, comprising a main body having an opening and a separator disposed in the opening, The main body comprises a first coupling portion, an anode current collector, and a stirring portion, which are configured to be detachably attached to the cathode unit of the zinc-air fuel cell. The main body contains an electrolyte solution containing zinc particles. Cartridge-type anode unit.

2. The cartridge-type anode unit according to claim 1, wherein the stirring section is a stirring bar configured to be rotatable by a magnetic stirrer.

3. A cathode unit having a second coupling portion detachably configured to connect to the first coupling portion of the cartridge-type anode unit according to claim 1 or 2.

4. An electric motor comprising the cathode unit described in claim 3.

5. An electric heater comprising the cathode unit described in claim 3.

6. A light source comprising the cathode unit described in claim 3.

7. A vehicle comprising the cathode unit described in claim 3.

8. An aircraft comprising the cathode unit described in claim 3.

9. A vessel comprising the cathode unit described in claim 3.

10. An electrical device comprising the cathode unit described in claim 3.

11. A power supply system comprising the cathode unit described in claim 3.

12. A zinc fuel regeneration apparatus having a water electrolysis tank configured to reduce the cartridge-type anode unit according to claim 1 or 2.

13. A zinc-air fuel cell comprising a cartridge-type anode unit according to claim 1 or 2 and a cathode unit according to claim 3.

14. A power supply system comprising a zinc-air fuel cell according to claim 13, connected in series.

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