Zinc-air secondary battery system

Abstract

The air-zinc secondary battery system of the present invention comprises an air-zinc battery array in a rectangular case, in which a plurality of air-zinc battery cells are connected, each having an air positive electrode part, a separator, and a zinc gel negative electrode part containing an electrolyte, an external electrolyte tank for storing electrolyte, and an electrolyte transport part configured to flow electrolyte from the external electrolyte tank into the zinc gel negative electrode part in each air-zinc battery cell, thereby circulating the electrolyte in the external electrolyte tank and the electrolyte in the zinc gel negative electrode part. The external electrolyte tank and the case are provided with gas vents, and the case is provided with an electrolyte inlet part for flowing electrolyte from the external electrolyte tank into the zinc gel negative electrode part, and an electrolyte outlet part for flowing electrolyte in the zinc gel negative electrode part to the outside, and the electrolyte outlet part is provided at a position higher than the position where the electrolyte inlet part is provided.

Description

[Technical Field]

[0001] The present invention relates to an air-zinc secondary battery system equipped with an electrolyte and gas flow system. [Background technology]

[0002] An electrochemical power source is a device that can generate electrical energy through an electrochemical reaction, and an air-zinc secondary battery is one such electrochemical power source. An air-zinc secondary battery employs a zinc gel anode made of zinc gel, which is converted to zinc oxide during discharge. The cathode employs an air cathode, which is a permeable membrane containing water molecules and generates hydroxide ions upon contact with oxygen in the air. A separator is disposed between the air cathode and the zinc gel anode. The separator prevents internal short circuits caused by direct contact between the air cathode and the zinc gel anode. It not only maintains ion passage within the battery but also plays an important role in improving battery safety.

[0003] Such zinc-air secondary batteries have many advantages over conventional hydrogen fuel cells. In particular, because fuels such as zinc exist abundantly as metals and their oxides, the energy supply provided by zinc-air secondary batteries is not visibly depleted. Furthermore, while conventional hydrogen fuel cells require recharging, zinc-air secondary batteries can be electrically recharged and used, and they have the advantage of being able to deliver a higher output voltage (1.4V) than conventional fuel cells (<0.8V).

[0004] In air-zinc secondary batteries, a slurry-type electrolyte solution, which is a mixture of zinc (Zn), potassium hydroxide (KOH), and water (HO), is generally used. This electrolyte solution is contained within the zinc gel negative electrode, and the electrolyte solution passes through the separator to impregnate a portion of the air positive electrode, forming a gas-liquid interface. Air-zinc secondary batteries configured as described above operate by the transfer of electrons generated when the zinc contained in the electrolyte solution reacts with oxygen in the air and changes to zinc oxide.

[0005] In the conventional air-zinc secondary battery described above, the water in the electrolyte is consumed during discharge of the air-zinc secondary battery, causing an increase in the concentration of potassium hydroxide in the electrolyte. As a result, potassium hydroxide precipitates in the air positive electrode, destroying the air positive electrode and reducing the performance of the air-zinc secondary battery. Furthermore, a sudden change in the electrolyte concentration causes zinc dendrites to form in the zinc gel negative electrode, further reducing the performance of the air-zinc secondary battery.

[0006] Therefore, a system for maintaining an optimum electrolyte concentration in such air-zinc secondary batteries is needed.

[0007] In addition, in a zinc-air secondary battery that can be discharged and recharged, the zinc in the zinc gel anode becomes zinc oxide as the battery is discharged, and conversely, when the battery is recharged, oxygen from the zinc oxide is separated and released, returning it to its original zinc state. In other words, when the battery is sufficiently discharged, the higher the oxygen release efficiency of the zinc gel anode, the higher the charging performance of the zinc-air secondary battery.

[0008] Therefore, in order to improve the charging performance of air-zinc secondary batteries, a system is required that supplies oxygen gas to the air positive electrode during discharge and discharges oxygen gas outside the air-zinc secondary battery during recharge. Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to provide an air-zinc secondary battery system that can maintain an optimal electrolyte concentration, efficiently supply oxygen gas to the air-zinc secondary battery during discharge, and efficiently discharge oxygen gas from the air-zinc secondary battery during recharge. [Means for solving the problem]

[0010] These objects can be achieved by the present invention described below in (1) to (7).

[0011] (1) A zinc-air battery array comprising a rectangular case and a plurality of zinc-air battery cells connected together, each cell having an air cathode, a separator, and a zinc gel anode containing an electrolyte therein; an external electrolyte tank for storing an electrolyte; and an electrolyte transport unit configured to flow the electrolyte from the external electrolyte tank into the zinc gel negative electrode portion in each of the air-zinc battery cells, thereby circulating the electrolyte in the external electrolyte tank and the electrolyte in the zinc gel negative electrode portion; the external electrolyte tank and the case are provided with gas vents; The case includes an electrolyte inlet portion for allowing the electrolyte from the external electrolyte tank to flow into the zinc gel negative electrode portion, and an electrolyte outlet portion for allowing the electrolyte from the zinc gel negative electrode portion to flow out, The air-zinc secondary battery system is characterized in that the electrolyte outlet portion is disposed at a position higher than a position where the electrolyte inlet portion is provided.

[0012] (2) An air-zinc secondary battery system as described in (1) above, in which the electrolyte outlet portion of one of the air-zinc battery cells and the electrolyte inlet portion of the other of the air-zinc battery cells are connected to each other.

[0013] (3) The air-zinc secondary battery system according to (1) above, wherein the separator is made of nonwoven fibers formed from a polymer solution using an electrospinning method.

[0014] (4) As the polymer solution, a mixture of Nafion and a polyacrylic acid solution is used, The air-zinc secondary battery system according to (1) above, wherein the nonwoven fiber has a sulfur skeleton derived from a Nafion structure and a rigid structure derived from polyacrylic acid.

[0015] (5) The air-zinc secondary battery system according to (1), wherein the zinc gel negative electrode portion contains an elastic conductive material. (6) The air-zinc secondary battery system according to (1), wherein the elastic conductive material is at least one of expanded graphite and graphene.

[0016] (7) The air-zinc secondary battery system described in (1) above, wherein the air positive electrode section has a slow oxygen transport membrane used when charging the air-zinc battery cell, and a fast oxygen transport membrane used when discharging the air-zinc battery cell, which has a higher oxygen transport capacity than the slow oxygen transport membrane. [Effects of the Invention]

[0017] According to the present invention, the electrolyte concentration in the air-zinc secondary battery cell, more specifically, the potassium hydroxide concentration in the electrolyte, can be maintained by circulating the electrolyte contained in the zinc gel negative electrode section and the electrolyte in the external electrolyte tank. In particular, in the present invention, the electrolyte outlet, which drains the electrolyte from the zinc gel negative electrode section to the outside, is positioned higher than the electrolyte inlet, which drains the electrolyte from the external electrolyte tank into the zinc gel negative electrode section. Therefore, by operating the electrolyte transport section, the electrolyte with a relatively high potassium hydroxide concentration that accumulates at the bottom of the zinc gel negative electrode section can be discharged from the electrolyte outlet located at the top of the zinc gel negative electrode section. This maintains the electrolyte concentration throughout the zinc gel negative electrode section, thereby suppressing the precipitation of potassium hydroxide in the air positive electrode section and the formation of zinc dendrites in the zinc gel negative electrode section. Furthermore, oxygen gas can be supplied to the air positive electrode section during discharge, and oxygen gas can be discharged to the outside of the air-zinc secondary battery during recharge. As a result, it is possible to provide an air-zinc secondary battery system that has high charging performance and maintains a high output voltage for a long period of time. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram showing a preferred embodiment of the air-zinc secondary battery system of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing the internal structure of the air-zinc battery cell provided in the air-zinc secondary battery system of FIG. [Figure 3] FIG. 3 is a cross-sectional view of the zinc-air battery cell of FIG. [Figure 4] FIG. 4 is a cross-sectional view schematically showing another example of the configuration of the air-zinc battery cell provided in the air-zinc secondary battery system of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention can be modified in various ways and can have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to the specific embodiments, and it should be understood that the present invention includes all modifications, equivalents, and alternatives that fall within the spirit and technical scope of the present invention. In describing the present invention, if it is determined that detailed description of related publicly known technology may obscure the gist of the present invention, such detailed description will be omitted.

[0020] The terms used in this application are merely used to describe specific embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly dictates otherwise. In this application, the terms "comprise" or "have" and the like are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood not to preclude the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0021] Terms such as "first," "second," etc. may be used to describe various components, but the components should not be limited by these terms. These terms are used only to distinguish one component from another.

[0022] Hereinafter, the air-zinc secondary battery system of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

[0023] Fig. 1 is a schematic diagram showing a preferred embodiment of the air-zinc secondary battery system of the present invention. Fig. 2 is a schematic diagram showing the internal structure of an air-zinc battery cell provided in the air-zinc secondary battery system of Fig. 1. Fig. 3 is a cross-sectional view of the air-zinc battery cell of Fig. 2.

[0024] As shown in Figure 1, the air-zinc secondary battery system 1 of this embodiment has an air-zinc battery array 100 consisting of a plurality of air-zinc battery cells 10 connected in series, an external electrolyte tank (not shown), and an electrolyte transport unit 20 that circulates the electrolyte in the external electrolyte tank and the electrolyte in each air-zinc battery cell 10. Prior to a detailed description of the air-zinc secondary battery system 1 of this embodiment, each air-zinc battery cell 10 included in the air-zinc secondary battery system 1 will be described.

[0025] <Zinc-air battery cell> As shown in FIGS. 2 and 3, the zinc-air battery cell 10 includes a rectangular case 11 and an air positive electrode portion disposed in the rectangular case 11. 12 The battery has a separator 13 and a zinc gel negative electrode portion 14 containing an electrolyte therein.

[0026] The case 11 is rectangular and has an air positive electrode part at the center. 12 The cell storage section 111 has a separator 13 and a zinc gel negative electrode section 14 stored therein. The surface of the cell storage section 111 on the side where the air positive electrode section 11 is disposed is provided with a seal. 12 A plurality of gas vent holes 112 are formed to supply air (oxygen) to the

[0027] The case 11 is also provided with an electrolyte inlet 113 that allows the electrolyte from the external electrolyte tank to flow into the zinc gel negative electrode portion 14, and an electrolyte outlet 114 that allows the electrolyte from the zinc gel negative electrode portion 14 to flow out. In this embodiment, the electrolyte inlet 113 and the electrolyte outlet 114 are arranged symmetrically with respect to the center of the case 11, and the electrolyte outlet 114 is arranged at a higher position than the electrolyte inlet 113.

[0028] Auxiliary electrolyte reservoirs 30 are provided on both sides of the cell storage section 111 via lattice filters 40. Each auxiliary electrolyte reservoir 30 is filled with a plurality of filters (not shown), and impurities in the electrolyte are filtered out through these filters and the lattice filters 40. The case 11 is also provided with exposed terminal portions (not shown) for passing current from the air-zinc battery cell 10 during discharge and for applying voltage to the air-zinc battery cell 10 during recharge.

[0029] As is commonly known, the air cathode part 12 comprises an air diffusion layer, a catalytic active layer, and a cathode current collector layer. The air diffusion layer is preferably made of a hydrophobic membrane material such as polytetrafluoroethylene (PTFE) to prevent moisture and carbon dioxide from the external air from entering the battery and extend the life of the air-zinc secondary battery. The catalytic active layer is made of a carbon material that reacts with the inflowing oxygen to cause the reaction shown in Chemical Formula 1 below. The cathode current collector layer collects electrons generated by the chemical reaction in the catalytic active layer and is preferably a mesh structure made of a conductive material such as metal.

[0030] [ka]

[0031] The separator 13 is interposed between the air positive electrode part 12 and the zinc gel negative electrode part 14 to prevent short-circuiting between them. It also plays a role in transferring hydroxide ions generated by a chemical reaction with oxygen in the catalytically active layer of the air positive electrode part 12 to the negative electrode part.

[0032] The separator 13 may be a membrane made of a resin material such as polypropylene, which has ion permeability, but it is preferable to use nonwoven fibers formed from a polymer solution using an electrospinning method.

[0033] Membranes that have traditionally been used as separators (e.g., propylene membranes) cannot control selective ion transport, and potassium ions (K + In contrast, the use of separator 13 made of nonwoven fibers formed from a polymer solution using an electrospinning method prevents the transport of specific ions such as potassium ions (K + ) can prevent the transport of certain ions.

[0034] More specifically, a mixed solution of Nafion and a polyacrylic acid solution is used as the polymer solution, and nonwoven fibers are formed by electrospinning, and the nonwoven fibers are used to form the separator 13. Nafion is a copolymer of tetrafluoroethylene and perfluoro-2-(2-fluorosulfonylethoxy)propylvinyl ether.

[0035] The nonwoven fiber formed by the electrospinning method has a sulfur skeleton derived from the Nafion structure and a rigid structure derived from polyacrylic acid. This sulfur skeleton is connected to the zinc gel anode part 14 and the air cathode part 15. 12 protons (H + ) transport channels. Each ion is a hydroxide ion (OH -), preventing potassium ions in the electrolyte from migrating to the air positive electrode portion 11. Preventing potassium ions from migrating to the air positive electrode portion 11 also promotes the formation of water, which is beneficial for stabilizing the electrolyte concentration. As a result, the concentration of the electrolyte is maintained, preventing potassium hydroxide from precipitating in the air positive electrode portion 12 and preventing zinc dendrites from forming in the zinc gel negative electrode portion 14.

[0036] The prepared separator 13 is attached to the air positive electrode part 12 by adhering, pressing, or heat laminating it on the positive electrode current collector layer side of the air positive electrode part 12 .

[0037] The zinc gel anode part 14 contains zinc gel in gel form, which is a mixture of zinc (Zn) and an electrolyte, and functions as an anode by undergoing the reaction of the following chemical formula 2. The electrolyte in the zinc gel anode part 14 is a slurry-type electrolyte mixture of zinc (Zn), potassium hydroxide (KOH), and water (HO), and is impregnated in the zinc gel.

[0038] [ka]

[0039] Water molecules are generated in the zinc gel anode part 14 by the reaction of Chemical Formula 2, and the generated water molecules move to the air cathode part 12 and are used in the chemical reaction of Chemical Formula 1.

[0040] 3, a plurality of protruding gel retaining pins 141 are provided on the surface of the case 11 opposite to the surface on which the gas vent holes 112 are formed. The zinc gel is held by the gel retaining pins 141 so as to cover the entire surface of the separator 13.

[0041] Furthermore, the zinc gel of the zinc gel negative electrode part 14 preferably contains an elastic conductive material, such as at least one of expanded graphite and graphene. The volume of the zinc gel negative electrode part 14 changes with each recharge and discharge cycle. This phenomenon causes the zinc gel negative electrode part 14 to aggregate, reducing its specific surface area. By including an elastic conductive material in the zinc gel of the zinc gel negative electrode part 14, aggregation of the zinc gel negative electrode part 14 is prevented, and the charge and discharge characteristics of the zinc-air battery cell 10 can be maintained. Furthermore, by including an elastic conductive material in the zinc gel, a gap necessary for more rapid electrolyte exchange between the electrolyte from the external electrolyte tank and the electrolyte in the zinc gel negative electrode portion 14 is formed. Furthermore, the above-mentioned effects can be obtained by incorporating a zinc alloy coil spring with increased tension into the zinc gel.

[0042] <Zinc-air secondary battery system> As described above, the air-zinc secondary battery system 1 of this embodiment has an air-zinc battery array 100 consisting of a plurality of air-zinc battery cells 10 connected in series, an external electrolyte tank (not shown), and an electrolyte transport unit 20 that circulates the electrolyte in the external electrolyte tank and the electrolyte in each air-zinc battery cell 10.

[0043] 1, the air-zinc battery array 100 is formed by connecting four air-zinc battery cells 10 in series. Two adjacent air-zinc battery cells 10 are connected to each other via respective liquid transfer tubes 23, 24, and 25 described below, at the electrolyte outlet portion 114 of one air-zinc battery cell 10 and the electrolyte inlet portion 113 of the other air-zinc battery cell 10. The number of air-zinc battery cells 10 constituting the air-zinc battery array 100 is not limited, and the air-zinc battery array 100 may be composed of a single air-zinc battery cell 10, or the air-zinc battery array 100 may be composed of any number of air-zinc battery cells 10 greater than or equal to two.

[0044] The external electrolyte tank is filled with unused electrolyte and has a capacity that can supply a sufficient amount of electrolyte to each of the air-zinc battery cells 10. The external electrolyte tank is also provided with a gas vent hole, through which oxygen gas contained in the electrolyte sent from each of the air-zinc battery cells 10 of the air-zinc battery array 100 can be discharged. The external electrolyte tank has an electrolyte outlet portion connected to the liquid supply tube 21 of the electrolyte transport portion 20, and an electrolyte inlet portion connected to the liquid supply tube 26 that carries the electrolyte discharged from each air-zinc battery cell 10 of the air-zinc battery array 100. By operating the electrolyte transport portion 20, the external electrolyte tank sends unused electrolyte from the electrolyte outlet portion and recovers the electrolyte discharged from each air-zinc battery cell 10 from the electrolyte inlet portion.

[0045] The electrolyte transport unit 20 is configured to flow electrolyte from the external electrolyte tank into the zinc gel negative electrode unit 14 in each air-zinc battery cell 10, circulating the electrolyte in the external electrolyte tank and the electrolyte inside the zinc gel negative electrode unit 14. The electrolyte transport unit 20 includes a liquid supply pump 200 such as a peristaltic pump, a liquid supply tube 21 connecting the electrolyte outlet of the external electrolyte tank to the liquid supply pump 200, a liquid supply tube 22 connecting the liquid supply pump 200 to the electrolyte inlet 113 of the first air-zinc battery cell 10 of the air-zinc battery array 100 (the first from the front in Figure 1), liquid supply tubes 23, 24, and 25 connecting the electrolyte outlet 114 of one of two adjacent air-zinc battery cells 10 to the electrolyte inlet 113 of the other air-zinc battery cell 10, and a liquid supply tube 26 connecting the electrolyte outlet 114 of the last air-zinc battery cell 10 of the air-zinc battery array 100 (the fourth from the front in Figure 3) to the electrolyte inlet of the external electrolyte tank.

[0046] When the liquid feed pump 200 is operated, unused electrolyte from the external electrolyte tank flows into the electrolyte inlet 113 of the first air-zinc battery cell 10 via the liquid feed tubes 21 and 22. Subsequently, the electrolyte in the first air-zinc battery cell 10 and unused electrolyte from the external electrolyte tank are discharged from the electrolyte outlet 114 and flow into the electrolyte inlet 113 of the second air-zinc battery cell 10 via the liquid feed tube 23. In this way, the electrolyte in each air-zinc battery cell 10 is replaced with unused electrolyte from the external electrolyte tank and is discharged from the electrolyte outlet 114 of the last air-zinc battery cell 10. The discharged electrolyte in each air-zinc battery cell 10 is sent to the external electrolyte tank via the liquid feed tube 26.

[0047] In this embodiment, the electrolyte contained in the zinc gel negative electrode portion 14 and the electrolyte in the external electrolyte tank are circulated, thereby maintaining the concentration of the electrolyte in each air-zinc battery cell 10, more specifically, the concentration of potassium hydroxide in the electrolyte. In particular, in the present invention, the electrolyte outlet 114 of each air-zinc battery cell 10 is disposed at a higher position than the electrolyte inlet 113 of each air-zinc battery cell 10. Therefore, by operating the liquid supply pump 200, the electrolyte with a relatively high potassium hydroxide concentration that has accumulated at the bottom of the zinc gel negative electrode section 14 can be discharged from the electrolyte outlet 114 located at the top of the zinc gel negative electrode section 14. This maintains the electrolyte concentration throughout the zinc gel negative electrode section 14, thereby suppressing the precipitation of potassium hydroxide in the air positive electrode section 12 and the formation of zinc dendrites in the zinc gel negative electrode section 14. During discharge, oxygen gas is supplied to the air cathode portion 12 through the gas vent 112 of the case 11, and during recharge, oxygen gas can be discharged to the outside of the air-zinc secondary battery together with the electrolyte. Due to the above-described effects, in the air-zinc secondary battery system 1 of this embodiment, each air-zinc battery cell 10 has high charging performance and can maintain a high output voltage for a long period of time.

[0048] In the air-zinc secondary battery system 1 of the present embodiment described above, the electrolyte in the external electrolyte tank and the electrolyte in the air-zinc battery cell 10 are circulated using the liquid pump 200, but the present invention is not limited to this. For example, the electrolyte in the external electrolyte tank and the electrolyte in the air-zinc battery cell 10 may be circulated by utilizing the difference in the concentration of the electrolyte.

[0049] Alternatively, the liquid supply pump 200 may be provided for each air-zinc battery cell 10. Furthermore, the electrolyte may be circulated between an external electrolyte tank and each air-zinc battery cell 10.

[0050] In the air-zinc battery cell shown in FIG. 3, one air positive electrode part 12 is arranged on one side of the zinc gel negative electrode part 14, but the following configuration may also be used. FIG. 4 is a cross-sectional view schematically showing another example of the configuration of the air-zinc battery cell provided in the air-zinc secondary battery system of the present invention.

[0051] In the air-zinc battery cell 10 shown in Fig. 4, a slow oxygen transport membrane 121 used when charging the air-zinc battery cell 10 is disposed on one side of the zinc gel negative electrode part 14 via a separator not shown. Also, a fast oxygen transport membrane 122 used when discharging the air-zinc battery cell 10 and having a higher oxygen transport capacity than the slow oxygen transport membrane 121 is disposed on the other side of the zinc gel negative electrode part 14 via a separator not shown. The fast oxygen transport membrane 122 is disposed on the side of the case 11 where the gas vent hole 112 is formed.

[0052] The high-speed oxygen transport membrane 122 has a higher oxygen transport rate than the low-speed oxygen transport membrane 121. During the charging reaction of the air-zinc battery cell 10, oxygen gas is produced from ZnO. This oxygen gas increases the internal pressure of the air-zinc battery cell 10, slowing the reaction rate during charging. In the configuration of FIG. 4, a voltage is applied between the low-speed oxygen transport membrane 121 and the zinc gel negative electrode portion 14 when charging the air-zinc battery cell 10. This suppresses the supply of oxygen through the low-speed oxygen transport membrane 121, and the action of the electrolyte transport portion 20 allows the oxygen gas to be efficiently discharged to the outside of the air-zinc battery cell 10 together with the electrolyte. 4, a voltage is applied between the high-speed oxygen transport membrane 122 and the zinc gel negative electrode portion 14 during discharge of the air-zinc battery cell 10. This allows oxygen to be efficiently supplied through the high-speed oxygen transport membrane 122, increasing the reaction rate during discharge. As a result, an air-zinc secondary battery system 1 with a high output voltage can be obtained.

[0053] As described above, it will be understood by those skilled in the art that the present invention can be embodied in other specific forms without changing the technical spirit or essential characteristics thereof. The scope of the present invention is defined by the following claims rather than the above detailed description, and all modifications and variations derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention. [Industrial Applicability]

[0054] According to the present invention, the electrolyte concentration in the air-zinc secondary battery cell, more specifically, the potassium hydroxide concentration in the electrolyte, can be maintained by circulating the electrolyte contained in the zinc gel negative electrode section and the electrolyte in the external electrolyte tank. In particular, in the present invention, the electrolyte outlet, which drains the electrolyte from the zinc gel negative electrode section to the outside, is positioned higher than the electrolyte inlet, which drains the electrolyte from the external electrolyte tank into the zinc gel negative electrode section. Therefore, by operating the electrolyte transport section, the electrolyte with a relatively high potassium hydroxide concentration that accumulates at the bottom of the zinc gel negative electrode section can be discharged from the electrolyte outlet located at the top of the zinc gel negative electrode section. This maintains the electrolyte concentration throughout the zinc gel negative electrode section, thereby suppressing the precipitation of potassium hydroxide in the air positive electrode section and the formation of zinc dendrites in the zinc gel negative electrode section. Furthermore, oxygen gas can be supplied to the air positive electrode section during discharge, and oxygen gas can be discharged to the outside of the air-zinc secondary battery during recharge. As a result, it is possible to provide an air-zinc secondary battery system that has high charging performance and maintains a high output voltage for a long period of time.Therefore, the present invention has industrial applicability.

Claims

1. a zinc-air battery array formed by connecting a plurality of zinc-air battery cells, each having an air positive electrode portion, a separator, and a zinc gel negative electrode portion containing an electrolyte solution, in a rectangular case; an external electrolyte tank for storing an electrolyte; and an electrolyte transport unit configured to flow the electrolyte from the external electrolyte tank into the zinc gel negative electrode portion in each of the air-zinc battery cells, thereby circulating the electrolyte in the external electrolyte tank and the electrolyte in the zinc gel negative electrode portion; the external electrolyte tank and the case are provided with gas vents; The case includes an electrolyte inlet portion for allowing the electrolyte from the external electrolyte tank to flow into the zinc gel negative electrode portion, and an electrolyte outlet portion for allowing the electrolyte from the zinc gel negative electrode portion to flow out to the outside, the separator is made of nonwoven fibers having a sulfur skeleton derived from a Nafion structure and a rigid structure derived from polyacrylic acid; The air-zinc secondary battery system is characterized in that the electrolyte outlet portion is disposed at a position higher than a position where the electrolyte inlet portion is provided.

2. The air-zinc secondary battery system of claim 1, wherein the electrolyte outlet of one of the adjacent air-zinc battery cells and the electrolyte inlet of the other air-zinc battery cell are connected to each other.

3. The air-zinc secondary battery system according to claim 1, wherein the zinc gel negative electrode portion contains an elastic conductive material.

4. 4. The air-zinc secondary battery system according to claim 3, wherein the elastic conductive material is at least one of expanded graphite and graphene.

5. The air-zinc secondary battery system according to claim 1, wherein the air positive electrode part has a slow oxygen transport membrane that is used when charging the air-zinc battery cell, and a high-speed oxygen transport membrane that is used when discharging the air-zinc battery cell and has a higher oxygen transport capacity than the slow oxygen transport membrane.

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