阅读说明：本技术 氧化还原液流电池 (Redox flow battery ) 是由 富田美由纪 铃木雅博 周婷婷 于 2018-12-18 设计创作，主要内容包括：提供一种能够抑制由于负极中产生氢气而发生的电池系统内的压力上升的氧化还原液流电池。氧化还原液流电池(1)具有：具备正极电极(11)、负极电极(12)和离子交换膜(13)的电池单元(10)；与正极电极(11)相对应,收纳含正极活性物质的电解液的正极侧电解液罐(20)；与负极电极(12)相对应,收纳含负极活性物质的电解液的负极侧电解液罐(30)；将电池单元(10)和正极侧电解液罐(20)连接的正极侧配管；以及将电池单元(10)和负极侧电解液罐(30)连接的负极侧配管,氧化还原液流电池(1)以电解液在电池单元(10)与正极侧电解液罐(20)和负极侧电解液罐(30)之间经由正极侧配管(21、22)、负极侧配管(31、32)循环的方式构成从而进行充放电,负极侧配管(31、32)在至少一部分的内表面侧设有氢氧化催化剂(40)。(Provided is a redox flow battery capable of suppressing a pressure rise in a battery system caused by hydrogen gas generation in a negative electrode. A redox flow battery (1) is provided with: a battery cell (10) provided with a positive electrode (11), a negative electrode (12), and an ion exchange membrane (13); a positive electrode side electrolyte tank (20) which corresponds to the positive electrode (11) and contains an electrolyte containing a positive electrode active material; a negative electrode side electrolyte tank (30) which corresponds to the negative electrode (12) and contains an electrolyte containing a negative electrode active material; a positive electrode-side pipe for connecting the battery cell (10) and the positive electrode-side electrolyte tank (20); and a negative-electrode-side pipe connecting the cell (10) and the negative-electrode-side electrolyte tank (30), wherein the redox flow battery (1) is configured so that the electrolyte circulates between the cell (10) and the positive-electrode-side electrolyte tank (20) and the negative-electrode-side electrolyte tank (30) via the positive-electrode-side pipes (21, 22) and the negative-electrode-side pipes (31, 32) to perform charging and discharging, and the negative-electrode-side pipes (31, 32) are provided with a hydrogen oxidation catalyst (40) on at least a part of the inner surface side.)

1. A redox flow battery comprises a battery cell, a positive electrode side electrolyte tank, a negative electrode side electrolyte tank, a positive electrode side piping and a negative electrode side piping,

the battery cell comprises a positive electrode, a negative electrode, and an ion exchange membrane that separates the positive electrode from the negative electrode,

the positive electrode side electrolyte tank is provided corresponding to the positive electrode and accommodates an electrolyte containing a positive electrode active material,

the negative electrode side electrolyte tank is provided corresponding to the negative electrode and accommodates an electrolyte containing a negative electrode active material,

the positive electrode-side pipe connects the battery cell and the positive electrode-side electrolyte tank,

the negative-side pipe connects the battery cell and the negative-side electrolyte tank,

the redox flow battery is configured such that the electrolyte circulates between the battery cell and the positive electrode side electrolyte tank and the negative electrode side electrolyte tank via the positive electrode side piping and the negative electrode side piping that connect the battery cell and the positive electrode side electrolyte tank and the negative electrode side electrolyte tank, respectively, and is charged and discharged,

the negative-side pipe is provided with a hydrogen oxidation catalyst on at least a part of the inner surface side.

2. The redox flow battery of claim 1,

the negative-electrode-side piping includes a negative-electrode-side outward piping and a negative-electrode-side return piping,

the negative-electrode-side outward pipe is a supply path of the electrolyte from the negative-electrode-side electrolyte tank to the battery cell,

the negative-electrode-side circuit pipe is a discharge path of the electrolyte from the battery cell to the negative-electrode-side electrolyte tank,

the hydrogen oxidation catalyst is provided on an inner surface side of at least a part of the negative electrode-side circuit pipe.

3. A redox flow battery as claimed in claim 2,

the cell unit includes a positive electrode-side cell on the positive electrode side and a negative electrode-side cell on the negative electrode side separated by the ion exchange membrane,

the negative electrode side circuit pipe connects the negative electrode side cell and the negative electrode side electrolyte tank,

the discharge port of the electrolyte of the negative electrode side cell is located at the top of the negative electrode side cell.

4. A redox flow battery as claimed in claim 2 or 3,

the hydrogen oxidation catalyst is provided at a position on the cell side of the negative electrode-side circuit pipe.

5. A redox flow battery as claimed in any one of claims 1 to 4,

the hydrogen oxidation catalyst is provided on an inner surface of the negative electrode-side pipe.

6. A redox flow battery as claimed in any one of claims 1 to 5,

is a vanadium redox flow battery.

Technical Field

The present invention relates to a redox flow battery.

Background

A redox flow battery is known as a large-capacity storage battery. A redox flow battery generally has an ion exchange membrane for isolating an electrolyte and electrodes disposed on both sides of the ion exchange membrane. In addition, charging and discharging can be performed by performing an oxidation reaction on one electrode and a reduction reaction on the other electrode at the same time using an electrolyte containing metal ions that are active materials that change in valence number by oxidation-reduction.

In a state of high charge depth of the redox flow battery, hydrogen ions (H) are generated at the negative electrode⁺) Accepting electrons (e)^-) To produce hydrogen (H)₂) The tendency of (c). If the generated hydrogen gas is accumulated in the circulation system constituting the battery, a problem such as a pressure rise in the circulation system occurs. In addition, management is required so that hydrogen gas does not leak to the outside of the circulation system constituting the battery and cause explosion or the like.

In order to solve such a problem of hydrogen gas generation in the negative electrode, for example, patent document 1 discloses a technique in which, in a vanadium redox battery, a hydrogen oxidation catalyst supported on the surface of a carbon material is provided on the surface of a positive electrode containing the carbon material or in a region on the positive electrode side in a battery cell, and the hydrogen gas generated in the negative electrode is oxidized by the action of the hydrogen oxidation catalyst supported on the surface of the carbon material. Patent document 2 discloses a technique in which a flow cell including at least two half cells each having different electric charges and separated by a separator and one tank each storing each electrolyte is provided, and at least one electrode is disposed in each half cell, and a common gas capacity is provided to connect the tanks, and at least one catalyst for reduction of a reaction target of a redox couple on the positive electrode side is disposed in the tank for the electrolyte on the positive electrode side so as to be in contact with both the electrolyte on the positive electrode side and the common gas capacity.

Prior art documents

Patent document 1: japanese patent laid-open publication No. 2016-186853

Patent document 2: japanese laid-open patent publication No. 2015-504233

Disclosure of Invention

However, the technique of patent document 1 requires the movement of hydrogen gas from the negative electrode to the positive electrode, and the equipment is complicated. Further, it is necessary to support a carbon material with a hydrogen oxidation catalyst. In addition, in the technique of patent document 2, a common gas capacity is required to connect the tank for the electrolyte on the positive electrode side and the tank for the electrolyte on the negative electrode side, and the like, and the structure of the electrolyte tank is limited. Therefore, other countermeasures against the hydrogen gas generated in the anode electrode are desired.

The present invention has been made in view of such circumstances, and an object thereof is to provide a negative electrode capable of effectively suppressing generation of hydrogen (H) gas in the negative electrode₂) The resulting pressure rise in redox flow batteries.

The present inventors have earnestly studied to solve the above problems. As a result, the present inventors have found that the above problems can be solved by providing a hydrogen oxidation catalyst in at least a part of the inner surface side of a negative electrode pipe connecting a negative electrode side electrolyte tank containing an electrolyte containing a negative electrode active material and a battery cell, and have completed the present invention. That is, the present invention provides the following technical means.

(1) A redox flow battery having a battery cell provided with a positive electrode, a negative electrode and an ion exchange membrane separating the positive electrode and the negative electrode, a positive electrode side electrolyte tank provided corresponding to the positive electrode and containing an electrolyte containing a positive electrode active material, a negative electrode side electrolyte tank provided corresponding to the negative electrode and containing an electrolyte containing a negative electrode active material, a positive electrode side pipe connecting the battery cell and the positive electrode side electrolyte tank, a negative electrode side pipe connecting the battery cell and the negative electrode side electrolyte tank, and a negative electrode side pipe connecting the redox flow battery with the electrolyte via the positive electrode side pipe and the negative electrode side pipe respectively connecting the battery cell and the positive electrode side electrolyte tank and the negative electrode side electrolyte tank And a negative electrode side pipe having a hydrogen oxidation catalyst provided on at least a part of an inner surface side thereof, and configured to circulate between the battery cell and the positive electrode side electrolyte tank and the negative electrode side electrolyte tank, thereby performing charging and discharging.

(2) The redox flow battery according to (1), wherein the negative-electrode-side piping includes a negative-electrode-side outward piping and a negative-electrode-side return piping, the negative-electrode-side outward piping is a supply path of the electrolyte from the negative-electrode-side electrolyte tank to the battery cell, the negative-electrode-side return piping is a discharge path of the electrolyte from the battery cell to the negative-electrode-side electrolyte tank, and the hydrogen oxidation catalyst is provided on an inner surface side of at least a part of the negative-electrode-side return piping.

(3) The redox flow battery according to (2), wherein the battery cell includes a positive electrode-side cell on the positive electrode side and a negative electrode-side cell on the negative electrode side separated by the ion exchange membrane, the negative electrode-side circuit pipe connects the negative electrode-side cell and the negative electrode-side electrolyte tank, and a discharge port of the electrolyte of the negative electrode-side cell is located at a top of the negative electrode-side cell.

(4) The redox flow battery according to (2) or (3), wherein the hydrogen oxidation catalyst is provided at a position on the cell side of the negative electrode side circuit pipe.

(5) The redox flow battery according to any one of (1) to (4), wherein the hydrogen oxidation catalyst is provided on an inner surface of the negative electrode side pipe.

(6) A redox flow battery according to any one of (1) to (5), which is a vanadium redox flow battery.

According to the redox flow battery of the present invention, a pressure rise due to the generation of hydrogen gas in the negative electrode can be effectively suppressed. Therefore, the redox flow battery of the present invention is a highly reliable redox flow battery.

Drawings

Fig. 1 is a schematic configuration diagram illustrating an example of a redox flow battery according to the present embodiment.

Detailed Description

Specific embodiments (hereinafter, referred to as "the present embodiment") will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the present invention.

Fig. 1 is a schematic configuration diagram illustrating an example of a redox flow battery according to the present embodiment. As shown in fig. 1, redox flow battery 1 according to the present embodiment includes battery cell 10, and battery cell 10 includes positive electrode 11, negative electrode 12, and ion exchange membrane 13 that separates positive electrode 11 and negative electrode 12. The redox flow battery 1 includes a positive electrode side electrolyte tank 20, a negative electrode side electrolyte tank 30, a positive electrode side pipe and a negative electrode side pipe, the positive electrode side electrolyte tank 20 is provided corresponding to the positive electrode 11 and stores an electrolyte containing a positive electrode active material, the negative electrode side electrolyte tank 30 is provided corresponding to the negative electrode 12 and stores an electrolyte containing a negative electrode active material, the positive electrode side pipe connects the battery cell 10 and the positive electrode side electrolyte tank 20, and the negative electrode side pipe connects the battery cell 10 and the negative electrode side electrolyte tank 30. Specifically, in the present embodiment, the battery cell 10 includes a positive electrode side cell 14 on the positive electrode 11 side and a negative electrode side cell 15 on the negative electrode 12 side, which are separated by an ion exchange membrane 13 for separating the positive electrode 11 and the negative electrode 12. Here, the positive electrode side cell 14 is a positive electrode chamber that houses the positive electrode 11. The negative electrode cell 15 is a negative electrode chamber that houses the negative electrode 12. The positive electrode cell 14 of the cell 10 is connected to the positive electrode-side electrolyte tank 20 by a positive electrode-side pipe, whereby the positive electrode electrolyte circulates between the positive electrode-side cell 14 and the tank 20. The negative electrode side cell 15 of the battery cell 10 is connected to the negative electrode side electrolyte tank 30 by a negative electrode side pipe, whereby the negative electrode electrolyte circulates between the negative electrode side cell 15 and the tank 30.

Although fig. 1 shows that redox flow battery 1 is provided as a single redox flow battery, it is preferable to use a redox flow battery in a form called a battery pack in which a plurality of redox flow batteries 1 are connected and provided as a minimum unit.

In the present embodiment, the positive-side piping that connects the battery cell 10 and the positive-side electrolyte tank 20 includes the positive-side outward piping 21 and the positive-side return piping 22, the positive-side outward piping 21 is a supply path of the electrolyte from the positive-side electrolyte tank 20 to the battery cell 10 (more strictly, the positive-side cell 14), and the positive-side return piping 22 is a discharge path of the electrolyte from the battery cell 10 to the positive-side electrolyte tank 20. The positive electrode-side outward pipe 21 is provided to connect the positive electrode-side electrolyte tank 20 to the bottom of the battery cell 10, and the positive electrode-side return pipe 22 is provided to connect the upper portion of the battery cell 10 to the positive electrode-side electrolyte tank 20.

In the present embodiment as well, the negative-side piping connecting the battery cell 10 and the negative-side electrolyte tank 30 includes the negative-side outward piping 31 and the negative-side return piping 32, the negative-side outward piping 31 is a supply path of the electrolyte from the negative-side electrolyte tank 30 to the battery cell 10 (more strictly, the negative-side cell 15), and the negative-side return piping 32 is a discharge path of the electrolyte from the battery cell 10 to the negative-side electrolyte tank 30. The negative electrode side outward pipe 31 is provided to connect the negative electrode side electrolyte tank 30 to the bottom of the battery cell 10, and the negative electrode side return pipe 32 is provided to connect the upper part of the battery cell 10 to the negative electrode side electrolyte tank 30. In fig. 1, the discharge port of the electrolyte from the negative electrode side cell 15 is located at the top (highest point) of the negative electrode side cell 15. With such a configuration, hydrogen gas generated in the negative electrode 12 is easily discharged from the negative electrode side cell 15, and the hydrogen gas can be suppressed from staying in the battery cell 10, which is preferable. The vertical direction of the highest point or the like represents a direction in which the redox flow battery is provided in the present embodiment.

In the present embodiment, the pump 23 is provided in the outgoing pipe 21 on the positive electrode side, and the pump 33 is provided in the outgoing pipe 31 on the negative electrode side. Further, the pump 23 and the pump 33 may be provided in the positive-side circuit pipe 22 and the negative-side circuit pipe 32, respectively, but if the liquid-sending pump is provided in the circuit pipes (the positive-side circuit pipe 22 and the negative-side circuit pipe 32) which are the discharge paths of the electrolytic solution from the battery cell 10 to the electrolytic solution tanks (the positive-side electrolytic solution tank 20 and the negative-side electrolytic solution tank 30), the pressure inside the battery cell 10 is easily reduced to generate bubbles, and therefore, it is preferable to provide the liquid-sending pump in the outward-route pipes (the positive-side outward-route pipe 21 and the negative-side outward-route pipe 31) in terms of enabling the liquid to be more efficiently and stably sent. Therefore, the pump 23 and the pump 33 are preferably provided in the outward pipes (the positive-side outward pipe 21 and the negative-side outward pipe 31) as in the present embodiment.

As described above, the redox flow battery 1 of the present embodiment is configured such that the pump 23 provided in the positive-side pipe and the pump 33 provided in the negative-side pipe are operated to circulate the electrolyte through the positive-side pipe (the positive-side outward pipe 21 and the positive-side return pipe 22) connecting the battery cell 10 and the positive-side electrolyte tank 20 and the negative-side pipe (the negative-side outward pipe 31 and the negative-side return pipe 32) connecting the battery cell 10 and the negative-side electrolyte tank 30. Thus, in redox flow battery 1, while an electrolyte solution containing an active material is circulated, a charge-discharge reaction is performed in battery cell 10, and electric power is stored (charged) or extracted (discharged). The direction of the arrow shown in the figure indicates the moving (circulating) direction of the electrolyte.

In the present embodiment, a hydrogen oxidation catalyst 40 is provided on at least a part of the inner surface side of the negative-electrode-side pipe (negative-electrode-side outward pipe 31, negative-electrode-side return pipe 32). Fig. 1 shows a case where the hydrogen oxidation catalyst 40 is provided at a position on the cell 10 side of the negative electrode side circuit pipe 32 and the inner surface of the negative electrode side circuit pipe 32 is provided as a hydrogen oxidation catalyst layer.

Here, during charging or discharging of redox flow battery 1, an oxidation reaction or a reduction reaction occurs in positive electrode 11 and negative electrode 12. The reaction in the case of a vanadium redox flow battery is exemplified below.

[ Charge ]

And (3) positive electrode: VO (vacuum vapor volume)²⁺+H₂O→VO₂ ⁺+e^-+2H⁺

Negative electrode: v³⁺+e^-→V²⁺

[ discharge ]

And (3) positive electrode: VO (vacuum vapor volume)₂ ⁺+e^-+2H⁺→VO²⁺+H₂O

Negative electrode: v²⁺→V³⁺+e^-

In a redox flow battery, hydrogen ions (H) are generated in the negative electrode 12 during charging, particularly during charging at a high charging depth⁺) Accepting electrons (e)^-) Resulting in hydrogen (H)₂) And (4) generating. If hydrogen gas is generated in this manner, the generated hydrogen gas stays in the battery cell 10 or circulates together with the electrolyte and stays in the negative electrode side electrolyte tank 30, the negative electrode side pipe, and the like. In particular, hydrogen gas is likely to adhere as bubbles to the inner surface of the pipe connecting the cell 10 and the negative electrode side electrolyte tank 30, and therefore hydrogen gas is likely to accumulate. If hydrogen gas is trapped in the system of the cell, problems such as pressure rise occur. However, in the present embodiment, the hydrogen oxidation catalyst 40 is provided on the inner surface side of the negative electrode side pipe through which the hydrogen gas generated in the negative electrode 12 circulates together with the electrolyte. Thus, hydrogen (H) gas is generated in the negative electrode 12₂) Is oxidized into hydrogen ions (H) by contacting with a hydrogen oxidation catalyst 40 provided on the inner surface side of the anode side pipe⁺). The hydrogen gas thus generated is oxidized into hydrogen ions, and the hydrogen ions can be dissolved in the electrolyte solution and recovered.

The oxidation reaction of hydrogen is a reaction represented by the following formula, and in order to continuously and efficiently perform the oxidation reaction of hydrogen, it is preferable to actively remove electrons (e) generated by the oxidation of hydrogen^-). For this purpose, the pipe portion of the negative electrode side pipe where the hydrogen oxidation catalyst is provided may be made conductive, and the conductive pipe portion may be electrically connected to a potential higher than the potential of the negative electrode 12. For example, as shown in FIG. 1, the conductive portion is configured to be capable of generating electrons (e)^-) The positive electrode 11 is connected to a resistor 41 so as to remove a sufficient amount of current.

H₂→2H⁺+2e^-

As described above, in the present embodiment, even if hydrogen gas is generated in the negative electrode 12, it can be oxidized by contacting the hydrogen oxidation catalyst 40 provided on the inner surface side of the negative electrode side pipe and recovered to hydrogen ions, so that the retention of hydrogen gas in the circulation system such as in the negative electrode side pipe, in the negative electrode side electrolyte tank 30, or in the battery cell 10 is suppressed, and as a result, the increase in pressure in the circulation system can be effectively suppressed. Thus, the redox flow battery of the present embodiment can effectively suppress a pressure increase due to the generation of hydrogen gas, and therefore, is a highly reliable redox flow battery. In addition, in the present embodiment, the hydrogen oxidation catalyst is provided in the negative electrode side pipe, and it is not necessary to move hydrogen from the negative electrode side to the positive electrode side as in the technique of patent document 1. In the present embodiment, it is not necessary to provide the positive electrode side electrolyte tank 20 and the negative electrode side electrolyte tank 30 with special configurations as in the technique of patent document 2, and the configurations of the positive electrode side electrolyte tank 20 and the negative electrode side electrolyte tank 30 are not particularly limited, and various configurations can be adopted.

The hydrogen oxidation catalyst may be provided on the inner surface side of the negative-electrode-side pipe, and is preferably provided at a position in the negative-electrode-side pipe where hydrogen is likely to accumulate. For example, the hydrogen oxidation catalyst may be provided in the negative electrode side outward passage pipe 31 or the negative electrode side return passage pipe 32, but is preferably provided in the negative electrode side return passage pipe 32 as in the present embodiment. Since the negative-electrode-side circuit pipe 32 is a discharge path of the electrolyte from the battery cell 10 to the negative-electrode-side electrolyte tank 30, the hydrogen gas generated at the negative electrode 12 in the battery cell 10 can be oxidized into hydrogen ions at an early stage by providing the negative-electrode-side circuit pipe 32 with a hydrogen oxidation catalyst.

The position at which the hydrogen oxidation catalyst is provided on the inner surface side of the negative-electrode-side circuit pipe 32 is not particularly limited, but is preferably provided at a position on the cell 10 side of the negative-electrode-side circuit pipe 32, that is, in the vicinity of an outlet (discharge port) of the electrolytic solution of the cell 10 near the negative electrode 12 that generates hydrogen gas in the negative-electrode-side circuit pipe 32, as shown in fig. 1. This is because the connection part of the negative-electrode-side circuit pipe 32 to the battery cell 10 is close to the negative electrode 12, and hydrogen gas generated at the negative electrode 12 is likely to accumulate. Fig. 1 shows an apparatus configuration in a case where the battery unit 10 and the negative-side electrolyte tank 30 are provided in parallel, the negative-side circuit pipe 32 is configured by a 1 st vertical pipe portion extending from an upper portion of the battery unit 10 in a substantially vertical direction, a horizontal pipe portion connected to the vertical pipe portion and extending in a substantially horizontal direction, and a 2 nd vertical pipe portion connected to the horizontal pipe portion and an upper portion of the negative-side electrolyte tank 30 and extending in a substantially vertical direction downward, and an example where the hydrogen oxidation catalyst 40 is provided over a connection portion with the battery unit 10 of the negative-side circuit pipe 32 and its vicinity (preferably, the entirety of the 1 st vertical pipe portion) is shown.

The mode of providing the hydrogen oxidation catalyst 40 on the inner surface side of the anode-side pipe is not particularly limited. For example, the hydrogen oxidation catalyst 40 may be formed by coating the inner surface of the negative-side piping with a hydrogen oxidation catalyst as shown in fig. 1. The hydrogen oxidation catalyst 40 may be a particulate hydrogen oxidation catalyst supported on the inner surface of the negative-electrode-side pipe. It is sufficient that at least a part of the hydrogen gas generated at the negative electrode 12 can be oxidized to hydrogen ions by the hydrogen oxidation catalyst 40, and it is preferable that all of the hydrogen gas generated at the negative electrode 12 be hydrogen ions.

The hydrogen oxidation catalyst 40 may be disposed on the inner surface side of the negative-electrode-side pipe, that is, in the negative-electrode-side pipe so as to be able to contact the hydrogen gas. For example, a mesh member having a gap of such a degree that the flow of the electrolytic solution is not inhibited may be provided in the negative electrode side pipe along a direction crossing the flow of the electrolytic solution, and the hydrogen oxidation catalyst may be supported on the mesh member.

In fig. 1, the hydrogen oxidation catalyst 40 is provided in a part of the negative-electrode-side circuit pipe 32, but the hydrogen oxidation catalyst 40 may be provided in at least a part of the negative-electrode-side circuit pipe, and may be provided over the entire inner surface of the negative-electrode-side circuit pipe 32, or over the entire inner surfaces of the negative-electrode-side outward pipe 31 and the negative-electrode-side circuit pipe 32, for example.

The hydrogen oxidation catalyst provided in the negative electrode-side pipe may be any catalyst capable of oxidizing hydrogen, and examples thereof include metals such as cobalt (Co), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt), and alloys and oxides thereof.

In redox flow battery 1 according to the present embodiment, positive electrode 11 and negative electrode 12 are not particularly limited, and known electrodes may be used. It is preferable that these electrodes 11 and 12 have a structure and a form that provide only the sites where the redox reaction of the active material in the electrolyte occurs in the battery cell 10 without reacting with themselves, and have excellent permeability of the electrolyte, a wide surface area as much as possible, and low resistance. The electrodes 11 and 12 preferably have excellent affinity with the electrolyte solution (aqueous solution) from the viewpoint of activation of the redox reaction, and preferably have a large hydrogen overvoltage and a large oxygen overvoltage from the viewpoint of not causing decomposition of water as a side reaction. Examples of the electrodes 11 and 12 include carbon materials such as carbon felt and carbon nanotube, and graphitized materials thereof.

In redox flow battery 1 according to the present embodiment, the electrolyte solution containing the positive electrode active material and the electrolyte solution containing the negative electrode active material are not particularly limited, and the electrolyte solution used in the conventional redox flow battery may be used. For example, in the case where redox flow battery 1 is a vanadium-based redox flow battery, the electrolyte containing the positive electrode active material is a sulfuric acid aqueous solution of a vanadium salt, which is a sulfuric acid aqueous solution containing vanadium in valence 4 and/or 5. The electrolyte containing the positive electrode active material may be a mixture of vanadium ions having a valence of 4/5 or a state in which vanadium ions having a valence of 5 are separated in a charged state. In addition, in the case where redox flow battery 1 is a vanadium-based redox flow battery, the electrolyte containing the negative electrode active material is a sulfuric acid aqueous solution of a vanadium salt, and is a sulfuric acid aqueous solution containing vanadium in valence 2 and/or valence 3. The electrolyte containing the negative electrode active material may be a mixture of 2-valent/3-valent vanadium ions or a state in which 2-valent vanadium ions are separated in a charged state. The electrolyte solution containing the positive electrode active material and the electrolyte solution containing the negative electrode active material may be aqueous solutions containing at least one or more electrochemically active materials, and examples of the electrochemically active materials include metal ions such as manganese, titanium, chromium, bromine, iron, zinc, cerium, and lead.

In the redox flow battery 1 according to the present embodiment, the ion exchange membrane 13 is a proton (H) as a charge carrier⁺) A membrane that can pass but not other ions. The ion exchange membrane may be a known cation exchange membrane. Specific examples thereof include perfluorocarbon polymers having sulfonic acid groups, hydrocarbon-based polymer compounds having sulfonic acid groups, polymer compounds doped with inorganic acids such as phosphoric acid, organic/inorganic hybrid polymers partially substituted with proton-conducting functional groups, proton conductors in which a polymer matrix is impregnated with a phosphoric acid solution or a sulfuric acid solution, and the like. Among these, perfluorocarbon polymers having sulfonic acid groups are preferable, and Nafion (registered trademark) is more preferable.

As described above, according to redox flow battery 1 of the present embodiment, by providing hydrogen oxidation catalyst 40 in at least a part of the inner surface side of the negative electrode side piping (negative electrode side outward piping 31, negative electrode side return piping 32) connecting cell 10 and negative electrode side electrolyte tank 30, it is possible to effectively suppress a pressure increase due to the generation of hydrogen gas in negative electrode 12. Therefore, the redox flow battery 1 with high reliability can be provided.

Description of the reference numerals

1 Redox flow battery

10 cell unit

11 positive electrode

12 negative electrode

13 ion exchange membrane

14 positive electrode side cell

15 negative electrode side cell

20 positive electrode side electrolytic solution tank

21 positive electrode side outward piping

22 positive electrode side circuit piping

23 Pump

30 negative electrode side electrolytic solution tank

31 negative electrode side outward-passage piping

32 negative electrode side circuit piping

33 pump

40 hydrogen oxidation catalyst

41 resistor