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 technology]

[0002] With the recent spread and advancement of mobile phones, electric vehicles, etc., there is a demand for higher capacity batteries, which are the power sources for these devices. In this context, zinc-air batteries utilize atmospheric oxygen as the positive electrode (air electrode) active material, causing an oxidation-reduction reaction of the oxygen, while at the negative electrode, an oxidation-reduction reaction of the zinc that constitutes the negative electrode occurs. As such, zinc-air batteries are attracting attention as high-capacity batteries with high energy density that are superior to the currently widely used lithium-ion batteries.

[0003] Zinc-air batteries as primary batteries have already been put to practical use and are in circulation, and have a high energy density. Much research is being done to turn zinc-air batteries into secondary batteries.

[0004] On the other hand, there are many challenges in converting zinc-air batteries into secondary batteries while keeping them in the battery form. Therefore, flow-type zinc-air batteries have been proposed with the aim of storing large amounts of energy (Patent Document 1, Non-Patent Document 1). Flow-type zinc-air batteries use zinc as the active material, and have a configuration in which a cell that handles the charging and discharging of the storage battery and a storage section for energy storage materials containing an electrolyte are each independently connected by piping. Flow-type zinc-air batteries allow continuous input of zinc fuel, making it easy to obtain stable output and maximize energy density. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2017-532724 [Non-patent literature]

[0006] [Non-Patent Document 1] Sharp Corporation, "Starting development of zinc-based energy storage technology to achieve carbon neutrality," Internet<https: / / corporate.jp.sharp / news / 220824-a.html> Summary of the Invention [Problem to be solved by the invention]

[0007] On the other hand, because flow-type zinc-air batteries require a flow mechanism, the active material tends to accumulate in the flow mechanism pathway, resulting in a decrease in the utilization efficiency of the active material, i.e., flow loss. Furthermore, 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 a fuel pipe and the power generation cells are conductive through the fuel, so the power generation cells can only be connected in parallel. Arranging them in series or a combination of series and parallel requires detailed design, such as closing the fuel pipe with a valve, making it difficult to increase the voltage.

[0008] Therefore, there is a demand for a technology to obtain a zinc-air fuel cell (zinc-air secondary battery) that is free from flow loss, can be easily miniaturized, and can be connected in series. [Means for solving the problem]

[0009] The gist of the present 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 portion includes a first coupling portion configured to be detachably attached to a cathode unit of the zinc-air fuel cell, an anode current collecting portion, and a stirring portion; An electrolyte containing zinc particles is provided inside the main body. Cartridge type anode unit. (2) The cartridge-type anode unit according to (1) above, wherein the stirring portion is a stirring bar configured to be rotatable by a magnetic stirrer. (3) A cathode unit having a second connecting part configured to be detachable from the first connecting part 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 comprising 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 ship equipped with the cathode unit described in (3) above. (10) A gas appliance comprising the cathode unit described in (3) above. (11) A power supply system including the cathode unit described in (3) above. (12) A zinc fuel regeneration device having a water electrolysis tank configured to perform reduction treatment on the cartridge-type anode unit described in (1) or (2) above. (13) A zinc-air fuel cell comprising the cartridge-type anode unit according to (1) or (2) above and the cathode unit according to (3) above. (14) A power supply system comprising the zinc-air fuel cells according to (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 which is free from flow loss, can be easily miniaturized, and can be connected in series. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic cross-sectional view of an example of the cartridge-type anode unit of the present invention. [Figure 2] FIG. 2 is a cross-sectional schematic diagram of the present cartridge-type anode unit having a first coupling portion coupled to a second coupling portion of a cathode unit of a zinc-air fuel cell. [Figure 3] FIG. 3 is a cross-sectional schematic diagram of the present cartridge-type anode unit 1 having a first coupling portion with external threads coupled to a second coupling portion with internal threads of a cathode unit of a zinc-air fuel cell. [Figure 4] FIG. 4 is a cross-sectional schematic diagram of the present cartridge-type anode unit having a first coupling portion with a protrusion coupled to a second coupling portion with a recess of a cathode unit of a zinc-air fuel cell. [Figure 5] FIG. 5 is a cross-sectional schematic diagram of an insertion-type cap-shaped opening / closing part that is placed over the separator of this cartridge-type anode unit. [Figure 6] FIG. 6 is a cross-sectional schematic diagram of a rotary cap-shaped opening / closing part placed over the separator of this cartridge-type anode unit. [Figure 7] FIG. 7 is a cross-sectional schematic diagram of an insertion-type cap-shaped opening / closing part that is placed over the separator of this cartridge-type anode unit. [Figure 8] FIG. 8 is a front view of a sliding cap-shaped opening / closing part having an opening and capable of sliding and rotating. [Figure 9] FIG. 9 is a cross-sectional view of a zinc-air fuel cell in which a cartridge-type anode unit and a cathode unit are combined, during discharging. [Figure 10] FIG. 10 is a cross-sectional schematic diagram of a cartridge-type anode unit 1 undergoing regeneration treatment (charging) in a zinc fuel regeneration device. [Figure 11] FIG. 11 is a graph showing the air electrode potential and discharge power density versus discharge current density in a zinc-air fuel cell constructed by connecting a charged cartridge-type anode unit to a cathode unit. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present disclosure relates to a cartridge-type anode unit for a zinc-air fuel cell, which has a main body portion with an opening and a separator arranged in the opening, wherein the main body portion has a first connecting portion configured to be detachably attached to a cathode unit of the zinc-air fuel cell, an anode current collecting portion, and a stirring portion, and the main body portion contains an electrolyte solution containing zinc particles.

[0013] The cartridge-type anode (negative electrode) unit of the present disclosure (hereinafter also referred to as the present cartridge-type anode unit) provides a zinc-air fuel cell that is free from flow loss due to accumulation of active material in the flow mechanism path, is easily miniaturized, and can be connected in parallel or in series.

[0014] Conventional general secondary batteries are connected to an electric motor or the like during use, and are charged by being connected to a charger or by being directly supplied with power while connected to the electric motor or the like, which results in the problem of long charging times.

[0015] In contrast, the present cartridge-type anode unit can be used as a cartridge, so it can be connected to a zinc-air fuel cell equipped with a cathode unit (air electrode unit) for use (discharge), and after use, it can be removed from the cathode unit, the zinc active material can be subjected to a reduction treatment, and charging can be performed. Furthermore, because the present cartridge-type anode unit can be used as a cartridge, there is no need to disassemble the anode unit to regenerate the zinc oxide. A charged version of the present cartridge-type anode unit can be connected to the cathode unit of a zinc-air fuel cell from which the present cartridge-type anode unit has been removed, eliminating the need for charging time. The present cartridge-type anode unit can be replaced in this way and used in an electric motor, etc.

[0016] Furthermore, this cartridge-type anode unit can be delivered (transported) as a single cartridge-type unit. Therefore, this cartridge-type anode unit has a very high energy density based on the volume of the cartridge-type unit, and the energy density relative to the delivery and storage costs is very high. 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 can be easily miniaturized and can handle zinc fuel per cartridge-type unit, making it suitable for use in small power supply systems, suitable for use in electric motors, electric heaters, light sources, etc., and can also be easily installed in vehicles, aircraft, ships, and electrical equipment. Furthermore, this cartridge-type anode unit allows for easy series connection of zinc-air fuel cells to which it is coupled, making it suitable for use in medium- to large-sized stationary power supply systems.

[0018] Furthermore, with this cartridge-type anode unit, zinc fuel can be handled on a cartridge-by-cartridge basis, and therefore used waste fuel can be collected on a cartridge-by-cartridge basis and subjected to reduction treatment (regeneration treatment).

[0019] A cross-sectional view of an example of the cartridge-type anode unit is shown in Figure 1. The cartridge-type anode unit 1 has a main body 10 having an opening 11 and a separator 12 disposed in the opening 11.

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

[0021] The main body 10 is a container that holds fuel, which is an electrolyte solution containing zinc particles. The material of the main body 10 is not particularly limited as long as it can hold fuel inside, but it can preferably be made of resin, metal, or a combination thereof. The resin is preferably a thermoplastic resin, more preferably polypropylene. The metal is preferably stainless steel. The main body 10 may be, for example, based on a polypropylene vial or may be a stainless steel metal container. When the stirring unit described below is operated from outside the main body 10 using a wireless signal, it is preferable that at least a portion of the main body 10 is made of a resin that is transparent to 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 shown in FIG. 1. When at least a portion of the main body 10 is made of a conductive metal, the metal portion may function as the anode current collector 14. When the cartridge-type anode unit 1 is connected to a 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 as long as it is a material that has conventionally been used as a current collector in secondary batteries, and can be, for example, a conductive metal plate, metal rod, etc. made of copper, SUS, nickel, etc., or a plate, rod, etc. made of a carbon material.

[0024] The main body 10 has an opening 11 for disposing a separator 12. The size of the opening 11 may be any size that does not substantially impair the cell characteristics as an internal resistance when the cartridge-type anode unit 1 is combined with a cathode unit described below and operated as an air-zinc fuel cell. The size of the opening 11 may be the same as or smaller than the cross-sectional area in the direction perpendicular to the longitudinal direction connecting the cartridge-type anode unit 1 and the cathode unit, and is preferably 50 to 100%, more preferably 60 to 90%, and even more preferably 70 to 80% of the cross-sectional area.

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

[0026] The separator 12 preferably has a thickness of 10 to 500 μm. When the main body 10 has a separator with the above-mentioned preferred thickness, it becomes easier to suppress leakage of the electrolyte during storage or transportation while suppressing a substantial increase in internal resistance when the cartridge-type anode unit 1 is connected to a cathode unit to form a zinc-air fuel cell.

[0027] The separator 12 may be any material as long as it is physically stable in the electrolyte and has ion conductivity, preferably having an ion conductivity of 1 mS / cm or more, more preferably 10 mS / cm or more. When the separator 12 has such a preferable ion conductivity, the zinc-air fuel cell to which the cartridge-type anode unit 1 is connected can exhibit good cell characteristics, and the reduction process (charging) of the cartridge-type anode unit 1 can be performed well.

[0028] The separator 12 may have a Gurley air permeability of, for example, 1 sec / 100 mL to 10,000 sec / 100 mL or more. The separator 12 preferably has a Gurley air 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. When the main body 10 has a separator with the above-mentioned preferred air permeability, it is possible to suppress a substantial increase in internal resistance when the cartridge-type anode unit 1 is connected to a cathode unit to form a zinc-air fuel cell, while also making it easier to suppress leakage of the electrolyte during storage or transportation. The air permeability can be measured using a Gurley air permeability tester (Gurley densometer).

[0029] The main body 10 has a first coupling part 13 configured to be detachable from the cathode unit of a zinc-air fuel cell. By having the main body 10 have the first coupling part 13 configured to be detachable from the cathode unit of a zinc-air fuel cell, the cartridge-type anode unit 1 can be used in a cartridge format. As illustrated in Figure 1, the main body 10 can have the first coupling part 13 on the outer circumferential surface close to the separator 12, on the bottom near the separator 12, or on 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 can have a concave shape that can accommodate 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 a separator 12.

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

[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 Fig. 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 fit into the protrusion 132. Fig. 4 is a cross-sectional schematic diagram of a cartridge-type anode unit 1 having a first coupling portion 13 with a protrusion 132 coupled to a second coupling portion 23 with a recess of a cathode unit 20 of a zinc-air fuel cell.

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

[0035] The main body 10 may have an openable / closable part located at a position that covers the separator 12. The openable / closable part can be closed during storage or transportation of the cartridge-type anode unit 1, and opened when connecting to a cathode unit of a zinc-air fuel cell or a zinc fuel regeneration device. By providing the main body 10 with an openable / closable part, leakage or evaporation of the electrolyte from the separator during storage or transportation can be prevented, even when a separator with low air permeability is used.

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

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

[0038] 5 shows a cross-sectional schematic diagram of the opening / closing part 30 in the form of an insertion cap that is placed over the separator 12 of the cartridge-type anode unit 1. The opening / closing part 30 can be fitted into the main body part 10 by making the outer circumferential dimensions of the first coupling part 13 and the inner circumferential dimensions of the opening / closing part 30 substantially the same.

[0039] When the main body 10 has a male thread 131 on the surface of the first coupling portion 13 as illustrated in Fig. 3, it can be covered with a cap-shaped opening / closing portion 30 having a female thread that can be threaded onto the male thread 131, as shown in Fig. 6. Fig. 6 is a cross-sectional schematic diagram of the rotatable cap-shaped opening / closing portion 30 placed over the separator 12 of the cartridge-type anode unit 1 in a position that covers it.

[0040] The separator 12 can be covered with the cap-shaped opening / closing part 30 by rotating the opening / closing part 30 in a relatively tightening direction so that the female thread of the cap-shaped opening / closing part 30 is screwed onto the male thread 131 of the first coupling part 13. To open the opening / closing part, the opening / closing part 30 can be removed from the main body part 10 by rotating the opening / closing part 30 in a loosening direction. The first coupling 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-shaped part in which the male thread and the female thread are screwed together, the opening / closing part 30 can be firmly fitted to the main body part 10, which can better prevent the opening / closing part from falling off when closed. Furthermore, because it is a rotating part, a strong force is not required to open the opening / closing part, and there is little wear on the male and female threads that are the fitting members.

[0041] When the main body 10 has a convex portion 132 on the surface of the first coupling portion 13 as illustrated in Fig. 4, it can be covered with a cap-shaped opening / closing part 30 having a concave portion that can fit into the convex portion 132, as shown in Fig. 7. Fig. 7 is a cross-sectional schematic diagram of an insertion-type cap-shaped opening / closing part 30 placed over a position that covers the separator 12 of a cartridge-type anode unit 1.

[0042] By pushing the main body 10 of the cartridge-type anode unit 1 into place so that the recess of the cap-shaped opening / closing part 30 fits into the protrusion 132 of the first coupling part 13, the separator 12 can be covered with the opening / closing part 30. The first coupling part 13 may have a recess, and the cap-shaped opening / closing part 30 may have a protrusion. If the opening / closing part has an insertion-type cap shape in which the protrusion fits into the recess, the opening / closing part 30 can be firmly fitted to the main body 10, which makes it more likely that the opening / closing part will fall off when closed. Furthermore, because it is an insertion-type, it is easy to connect it to the main body with a band or the like, which makes it more likely that it will fall off from the main body 10 when opened.

[0043] When the separator 12 is located at the end of the main body 10 rather than at the center, an opening / closing unit 30 having an opening 301 and slidably rotatable in a direction parallel to the surface of the separator 12 can be placed over the separator 12. FIG. 8 shows a schematic front view of a cap-shaped opening / closing unit 30 having an opening 301 and slidably rotatable. The arrow indicates the direction in which the opening / closing unit 30 can slide and rotate. The cap-shaped opening / closing unit 30 having an opening 301 and slidably rotatable, placed over the separator 12, can be rotated and fixed in a position that covers the separator 12 during storage and transportation, and fixed in a position that exposes the separator 12.

[0044] The main body 10 of the cartridge-type anode unit 1 includes a stirring unit. The stirring unit can stir the electrolyte contained in the main body 10. Zinc particles in the electrolyte can coarsen and dendrites can grow during charging and discharging, but stirring the electrolyte with the stirring unit can prevent this. Without being bound by theory, coarsening of zinc particles can occur as zinc undergoes repeated oxidation and reduction in the electrolyte, and zinc oxide that can precipitate can be contained in the coarse particles. Because zinc forms dendritic during charging, it tends to become a lower-energy state as a crystal, reducing its surface area and causing coarsening when it is oxidized and reduced at the solid-liquid interface.

[0045] The stirring unit may be configured to be capable of stirring by electrical or magnetic energy applied from outside the main body 10. The stirring unit may be configured to be capable of adjusting the stirring intensity by varying the strength of the energy applied from outside. The stirring unit may also be configured to be capable of controlling the stirring operation by a wireless or wired signal from outside the main body 10. The stirring unit provides mechanical stirring to the electrolyte, and may be a stirrer that rotates by magnetic force, an ultrasonic stirrer, a screw-type stirrer, a mechanism that has fixed blades inside the main body 10 and rotates the cartridge-type anode unit 1 to provide stirring, or the like.

[0046] The stirring section is preferably disposed between the anode current collector 14 and the separator 12, and more preferably disposed adjacent to or in contact with the surface of the separator 12, at least during the reduction treatment (charging). FIG. 1 schematically shows an embodiment in which the stirring section 16 is disposed in contact with the surface of the separator 12. When zinc oxide in the electrolyte is reduced to zinc, zinc dendrites may grow toward the counter electrode (cathode). However, by locating the stirring section 16 preferably between the anode current collector 14 and the separator 12, and more preferably adjacent to or in contact with the surface of the separator 12, dendrite growth stops near the stirring section 16, thereby preventing dendrites from escaping the separator 12. Because the stirring section 16 is mechanical, its dendrite growth suppression effect is significantly greater than the chemical action of conventionally used complexing agents. The complexing agent diffuses to the cathode (positive electrode) side when dissolved in the electrolyte, and is oxidized and deteriorated during the oxygen generation reaction at the cathode, making it difficult to apply to long-term regeneration and utilization cycles.

[0047] The stirring unit 16 is preferably a stirring bar of a magnetic stirrer. The stirring bar can be rotated by magnetic force generated by the magnetic stirrer. The stirring bar can be rotated by magnetic force applied from a magnetic stirrer arranged outside the main body 10, and its position within the main body 10 can be easily adjusted. For example, a magnetic stirrer can be arranged outside the main body 10 at a position facing the stirring unit 16 across the separator 12, and the cartridge-type anode unit 1 can be arranged in the central region of the magnetic stirrer with the separator 12 facing downward, and the stirring bar can be placed in the center above the separator 12 and rotated by magnetic force. A stirring bar is also preferable from the standpoints of cost and maintenance, since it does not require complex mechanical structures or wiring within 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, and can be an aqueous electrolyte, an organic electrolyte, or a combination thereof. The electrolyte may be a liquid electrolyte, a gel electrolyte, a polymer electrolyte, or a combination thereof, as long as it has fluidity. From the viewpoint of safety, the electrolyte is preferably an aqueous electrolyte, or an electrolyte in which an aqueous electrolyte is primarily a mixed organic electrolyte or organic electrolyte.

[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, fluorine-containing polyethylene glycols, etc. One or more organic electrolytes can be used.

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

[0051] The concentration of the electrolyte in the electrolytic solution is not particularly limited and can be any concentration. The electrolytic solution may be weakly acidic, neutral, or alkaline, and the pH of the electrolytic 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 a combination thereof. The zinc particles preferably have an average particle size (diameter) within 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 the zinc particles, the electrolyte may further contain particles of other metals or metal compounds such as magnesium particles, aluminum particles, iron particles, or copper particles. The 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 may be a conventionally used catalyst, preferably carbon particles. The carbon particles may be graphite, carbon fiber, carbon black, carbon nanoparticles, etc. The ratio of carbon particles to zinc particles is preferably within the range of 2.5 to 10 mass %. The ratio of electrolyte in the zinc-containing electrolyte is preferably within the range of 50 to 80 volume %.

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

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

[0056] The main body 10 of the cartridge-type anode unit 1 can have 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 from top to bottom by gravity, such as in a beverage vending machine, charged cartridge-type anode units 1 can be sequentially fed and connected to the cathode unit of a zinc-air fuel cell from which a used cartridge-type anode unit 1 has been removed.

[0057] The present disclosure also relates to a cathode unit (air electrode unit) having a second coupling part configured to be detachable from the first coupling part of the above-mentioned cartridge-type anode unit 1. A zinc-air fuel cell can be constructed by coupling the above-mentioned 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 reduced (charged) cartridge-type anode unit 1 can be attached to this cathode unit, allowing it to be used as a zinc-air fuel cell. A used cartridge-type anode unit 1 can be subjected to a reduction treatment (charge).

[0058] 2 shows a 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 allows the first coupling part 13 to be inserted or fitted into it, 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 the second bonding portion 23 and functions as an air electrode, and may have a configuration of a conventionally used air electrode. The cathode unit 20 may 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 a cathode current collector such as a metal mesh. The water-repellent layer can be a conventionally used water-repellent layer, for example, a porous membrane of polytetrafluoroethylene (PTFE). The catalyst layer can be a conventionally used catalyst layer, for example, a mixed layer of carbon and a 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 ketjen black, acetylene black, denka black, carbon nanotubes, fullerene, metal, metal oxide, metal hydroxide, metal sulfide, or the like, and one or more of these can be used.

[0062] The mass ratio of the catalyst contained in the catalyst layer is preferably 5 mass% or more, more preferably 10 mass% or more, and even more preferably 20 mass% or more, based on 100 mass% of the catalyst layer. The mass ratio of the catalyst contained in the catalyst layer is preferably 98 mass% or less, more preferably 95 mass% or less. When the catalyst ratio is within the above preferred range, the air electrode can function more satisfactorily.

[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 either thermoplastic or thermosetting, and examples of the binder include halogen atom-containing polymers such as polyvinylidene fluoride and polytetrafluoroethylene, hydrocarbon moiety-containing polymers such as polyolefin, aromatic group-containing polymers such as polystyrene, ether group-containing polymers such as alkylene glycol, hydroxyl group-containing polymers such as polyvinyl alcohol, amide bond-containing polymers such as polyamide and polyacrylamide, imide group-containing polymers such as polymaleimide, carboxyl group-containing polymers such as poly(meth)acrylic acid, carboxylate group-containing polymers such as poly(meth)acrylate, sulfonate moiety-containing polymers, quaternary ammonium salt- or quaternary phosphonium salt-containing polymers, ion-exchange polymers, natural rubber, artificial rubber such as styrene butadiene rubber (SBR), sugars such as hydroxyalkyl cellulose (e.g., hydroxyethyl cellulose) and carboxymethyl cellulose, amino group-containing polymers such as polyethyleneimine, and polyurethane.

[0064] The mass proportion of the binder in the catalyst layer is preferably 0.1 to 10 mass %, more preferably 0.5 to 8 mass %, and even more preferably 1 to 5 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 cathode layer 22 may further comprise a gas diffusion layer (GDL), which allows air to enter from the outside and may comprise a layer of carbon particles and platinum particles with some hydrophobic agent, 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 of any material that has been conventionally used as a current collector, including carbon paper, porous structures such as metal mesh, mesh structures, fibers, nonwoven fabrics, etc. For example, a metal mesh made of SUS, nickel, aluminum, iron, titanium, etc. can be used. A metal foil having oxygen supply holes can also be used as the cathode current collector.

[0068] The cathode unit can be provided in a machine requiring electricity. Preferably, the cathode unit can be provided in an electric motor, an electric heater, or a light source. 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 and air conditioners (including cooling and dehumidification). Examples of light sources include flashlights, outdoor lighting devices for construction work, etc., lasers, camping lights, tent lights, and lights for underground shelters.

[0069] The cathode unit can also be preferably 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, snow scooters, and trains. The cathode unit can also be used as an auxiliary power source for vehicles, an alternative power source to lead-acid batteries, and the like. It is desirable for the cathode unit to be placed on the left side of a domestic vehicle or on the right side of a US vehicle, with an opening for loading and unloading the cartridge-type anode unit. Examples of aircraft include general jet aircraft (passenger aircraft, cargo aircraft), electric propeller aircraft (passenger aircraft, cargo aircraft), drones, satellites, space stations, and the like. Examples of ships include leisure motorboats, jet skis, submarines, and general ships.

[0070] The electrical equipment may be any electrical equipment that can be generally used, and examples thereof include communication equipment, household electrical appliances, measuring equipment, 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 sources for buildings or hospitals, stationary power sources, etc., such as storage of commercial and industrial power, power storage for residential solar cells, power storage for building microgrids, power storage to replace peaking plants, backup power sources for renewable energy, power storage for integrating renewable energy systems, seasonal energy storage, and power storage for grid services (especially for demand response, ancillary services, governor-free operation, frequency adjustment, etc.), and portable power sources are also acceptable.

[0072] In a vehicle, aircraft, ship, electrical equipment, or power supply system, the cathode units can be connected in series, in parallel, or in series and parallel.

[0073] The present disclosure is also directed to a zinc fuel regeneration device having a water electrolysis cell configured to perform reduction treatment on the cartridge-type anode unit 1 described above.

[0074] During discharge (power generation) of a zinc-air fuel cell combining a cartridge-type anode unit 1 and a cathode unit 20, the zinc active material, which serves as fuel, is oxidized in the main body 10. Figure 9 shows a schematic cross-sectional view of a zinc-air fuel cell combining 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 in the main body 10 is oxidized, and electrolyte 18 containing zinc oxide is produced from the cathode unit side.

[0075] The waste fuel containing the produced zinc oxide is collected while still mounted on the cartridge-type anode unit 1. The zinc oxide in the collected 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 can become coarse, but stirring the electrolyte in the stirring section can suppress the zinc coarsening and dendrite growth.

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

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

[0078] The zinc fuel regeneration device 40 has a holder capable of holding the cartridge-type anode unit 1 , and preferably, the container 41 has a holder capable of holding the cartridge-type anode unit 1 .

[0079] The structure of the holder is not particularly limited as long as it can hold the cartridge-type anode unit 1. It may have a structure that maintains the horizontal orientation of the cartridge-type anode unit 1 supported on the bottom of the container 41 so that it does not tip over due to gravity, or it may have a structure that maintains the horizontal and vertical orientation of the cartridge-type anode unit 1. For example, the container 41 may be provided with a fixing jig having a hole with a diameter substantially equal to or slightly larger than the outer diameter of the cartridge-type anode unit 1 to maintain the horizontal orientation of the cartridge-type anode unit 1. Alternatively, the container 41 may be provided with a fixing jig having a hole with an outer diameter substantially equal to or slightly larger than the outer diameter of the cartridge-type anode unit 1 and a tightening mechanism for the hole to maintain the horizontal and vertical orientation of the cartridge-type anode unit 1. The zinc fuel regeneration device may have a third connecting part configured to be detachable from the first connecting part. The third connecting part may have any configuration as long as it can conduct ions through the separator 12, and may have a configuration similar to that of the second connecting part described above.

[0080] Preferably, the cartridge-type anode unit 1 is placed in the aqueous solution 43 in the container 41 so that a gap is formed between the separator 12 and the bottom surface of the container 41. The gap may be formed by placing a nonwoven fabric or the like on the bottom of the container 41. By providing a gap between the separator 12 and the container 41, electrical conductivity between the inside and outside of the main body 10 can be more reliably ensured.

[0081] The zinc fuel regeneration device 40 preferably includes a magnetic stirrer 44 that generates a magnetic force to rotate the stirring unit 16, which is a stirring bar inside the main body 10. The magnetic stirrer 44 may include a magnet and a variable speed motor that rotates the magnet. The cathode unit may also include a magnetic stirrer. The magnetic stirrer 44 rotates the stirring unit 16 as shown by the arrow in FIG. 10, thereby stirring the electrolyte inside the main body 10.

[0082] The present disclosure also relates to a zinc-air fuel cell including the above-mentioned cartridge-type anode unit 1 and the above-mentioned cathode unit 20. This zinc-air fuel cell contains an electrolyte solution containing a zinc active material as a zinc fuel in the main body 10. The zinc-air fuel cell can be configured and used for discharge by connecting the cartridge-type anode unit 1 to the second coupling part 23 of the cathode unit 20.

[0083] Multiple zinc-air fuel cells can be connected in series, in parallel, or in series and in parallel. Particularly in power supply systems, which are relatively large-scale, stationary facilities that temporarily store electricity, connecting zinc-air fuel cells in series can output a relatively high voltage. [Example]

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

[0085] (Fabrication of cathode unit) Ketjen black, PTFE aqueous dispersion (solid content Nv 60%), and water were mixed in a mass ratio of 10:1:2, placed in a polyethylene bag, and rolled using a roll press with a 0.5 mm gap between the rolls to obtain a flat paste. The resulting flat paste was rolled onto a Ni-plated SUS mesh used as a current collector to form an integrated plate. A PTFE water-repellent film (100 μm thick, Gurley value 18 sec / 100 mL) was then rolled onto one side to form an air cathode layer (oxygen reduction electrode).

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

[0087] The prepared oxygen reduction electrode was attached to the end face of the acrylic resin housing opposite the second joint, to prepare a cathode unit as shown schematically in FIG.

[0088] (Fabrication of zinc-air fuel cells) The first connecting part of the cartridge-type anode unit was fitted to the second connecting part of the cathode unit so that the nonwoven fabric attached to the vial lid of the cartridge-type anode unit came into contact with the nonwoven fabric placed in the cathode unit, thereby producing a zinc-air fuel cell as shown schematically in Figure 2. When fitted together, the electrolytes impregnated in the nonwoven fabrics mixed together, forming an ion conduction path that enabled discharge.

[0089] (Measurement of electrical characteristics) A discharge test was carried out 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 carried out using a Hokuto Denko charge / discharge tester HJ1001SD8, with a discharge current of 0.1 mA / cm. 2 ~200mA / cm 2The discharge voltage was measured while changing the discharge current, and the discharge power at each discharge current was calculated.

[0090] Figure 11 shows a graph of the air electrode potential and discharge power density versus discharge current density for the fabricated zinc-air fuel cell. 2 Starting from just under 1.4 V in an open circuit, the current density was increased to approximately 100 mA / cm. 2 It was confirmed that the electrical characteristics were such that the discharge power density was at its maximum.

[0091] Example 2 A cartridge-type anode unit was fabricated in the same manner as in Example 1, except that 1 g of metallic zinc powder was placed in the vial, and a zinc-air fuel cell was fabricated by combining it with a cathode unit in the same manner as in Example 1. The fabricated zinc-air fuel cell had a theoretical capacity of 820 mAh / g and a current of 10 mA / cm. 2 It showed a discharge capacity of 750 mAh / g at a discharge current of 100 mAh / g.

[0092] After discharge, the cartridge-type anode unit was removed from the zinc-air fuel cell and placed in an aqueous potassium hydroxide solution in a container of a zinc fuel regeneration device equipped with a magnetic stirrer, as shown in Figure 10. While stirring the electrolyte by rotating the stirrer inside the main body of the cartridge-type anode unit with the magnetic stirrer, water was electrolyzed using the electrodes, and the current was kept at 10 mA / cm, the same as during discharge. 2 The zinc oxide produced in the main body was regenerated by a charging reaction at a current rate of 1000 mAh / g. 748 mAh / g of zinc was regenerated through the regeneration process. 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 Separator 13 First joint 131 Male thread 132 Convex part 14 Anode current collector 15 Zinc-containing electrolyte 16 Stirring section 18 Electrolyte containing zinc oxide 20 Cathode unit of zinc-air fuel cell 22 Air electrode layer 23 Second Joint 24 Electrolyte layer 30 Opening and Closing Section 301 Opening of opening and closing part 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 body having an opening; and a separator disposed in the opening, the main body portion includes a first coupling portion configured to be detachably attached to a cathode unit of the zinc-air fuel cell, an anode current collecting portion, and a stirring portion; An electrolyte containing zinc particles is provided inside the main body. Cartridge type anode unit.

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

3. 3. A cathode unit having a second coupling part configured to be detachable from the first coupling part of the cartridge-type anode unit according to claim 1.

4. An electric motor comprising the cathode unit according to claim 3.

5. An electric heater comprising the cathode unit according to claim 3 .

6. A light source comprising the cathode unit according to claim 3 .

7. A vehicle comprising the cathode unit according to claim 3.

8. An aircraft comprising the cathode unit according to claim 3.

9. A vessel comprising the cathode unit according to claim 3 .

10. An electric device comprising the cathode unit according to claim 3 .

11. A power supply system comprising the cathode unit according to claim 3 .

12. A zinc fuel regeneration device having a water electrolysis cell configured to perform reduction treatment on the cartridge-type anode unit according to claim 1 or 2.

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

14. 14. A power supply system comprising the zinc-air fuel cells of claim 13 connected in series.

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