Carbon dioxide adsorption battery and charge / discharge device

Abstract

One aspect of the present invention is a carbon dioxide adsorption battery comprising: a positive electrode; a negative electrode; a separator disposed between the positive electrode and the negative electrode; an electrolyte layer disposed between the negative electrode and the separator; and a flow path connected to the negative electrode. The electrolyte layer includes an electrolyte capable of dissolving carbon dioxide, and a compound capable of adsorbing and desorbing carbon dioxide by electrochemical reaction. The negative electrode is an electrode capable of transmitting gas, and the positive electrode is provided with a porous electrode containing an electrolyte.

Description

Carbon dioxide adsorption battery and charging / discharging device

[0001] The present invention relates to a carbon dioxide adsorption battery and a charge / discharge device.

[0002] Carbon dioxide is not only widely distributed on Earth, accounting for approximately 0.04% of the atmosphere, but is also widely used in industry. Examples of uses of carbon dioxide include foaming gas for carbonated beverages, bath additives, and fire extinguishing agents, dry ice used for cooling, and emergency air refills for bicycle tires. Carbon dioxide can also be used as an extraction solvent for extracting caffeine and other substances by bringing it to a supercritical state. Carbon dioxide is also used in lasers used in industrial processing and carbon dioxide lasers used in medical laser scalpels. Furthermore, carbon dioxide is sometimes used as a compressor refrigerant instead of a fluorocarbon-based refrigerant. Carbon dioxide is also used in agriculture, for example, for carbon dioxide fertilization to accelerate the growth of plants such as strawberry forcing and aquatic plants in ornamental aquariums. Carbon dioxide is also used in controlled atmosphere (CA) storage of fresh agricultural produce.

[0003] As described above, carbon dioxide is used in various fields, and therefore, there is a demand for a method of obtaining carbon dioxide by, for example, separating carbon dioxide from a gas containing carbon dioxide, such as air. Carbon dioxide is also said to be a causative substance of global warming. For this reason, there is a demand for separating carbon dioxide from a gas containing carbon dioxide and utilizing the carbon dioxide. In order to utilize carbon dioxide, there is a demand for the development of, for example, a method of separating carbon dioxide from a gas containing carbon dioxide, an apparatus for adsorbing and separating carbon dioxide, and an apparatus for utilizing carbon dioxide.

[0004] Various methods have been proposed for separating carbon dioxide from a mixed gas containing oxygen and carbon dioxide, such as air. Examples of such separation methods include a method in which a carbon dioxide adsorbent is used to adsorb carbon dioxide in the air, and then the carbon dioxide adsorbed by the adsorbent is desorbed, thereby separating carbon dioxide from the air. Examples of adsorbents that adsorb carbon dioxide include activated carbon, amine solvents, and aqueous potassium carbonate solutions. More specifically, examples of carbon dioxide separation methods using an adsorbent include pressure swing adsorption (PSA), in which carbon dioxide is adsorbed onto an adsorbent under high pressure, and then the pressure is reduced to desorb the carbon dioxide from the adsorbent. Examples of adsorbents used in separating carbon dioxide using this PSA method include the adsorbents described in Patent Document 1.

[0005] Patent Document 1 describes a carbon dioxide adsorbent comprising a composition in which 2 to 80 equivalent percent of the sodium ions in a sodium-containing aluminosilicate have been ion-exchanged with barium ions. Patent Document 1 discloses that it is possible to provide an adsorbent that has a high selectivity for carbon dioxide and a large absorption capacity even under conditions of high moisture content. Patent Document 1 also discloses that this adsorbent can be suitably used for separating and concentrating carbon dioxide by a PSA method.

[0006] Examples of devices for adsorbing and separating carbon dioxide include an acidic gas adsorption / desorption device described in Patent Document 2 and a carbon dioxide separation device described in Patent Document 3.

[0007] Patent Document 2 describes an acidic gas adsorption / desorption device having an acidic gas adsorption / desorption layer including a compound and a substrate that can adsorb and desorb acidic gases such as carbon dioxide by oxidation and reduction, and a pair of electrodes that sandwich the acidic gas adsorption / desorption layer.

[0008] Patent Document 3 describes a carbon dioxide separation device that includes an electrolyte layer, a pair of electrodes disposed on the electrolyte layer with the electrolyte layer sandwiched therebetween, and a voltage application unit that applies a voltage between the pair of electrodes, wherein each of the pair of electrodes is gas-permeable, and the electrolyte layer contains an electrolytic solution that can dissolve carbon dioxide and a redox compound having an N-oxy radical group in its molecule.

[0009] Examples of devices that utilize carbon dioxide include the batteries described in Non-Patent Documents 1 and 2.

[0010] Non-Patent Document 1 proposes a method for utilizing carbon dioxide, in which a battery is charged while absorbing carbon dioxide.

[0011] Non-Patent Document 2 proposes a carbon dioxide rechargeable battery incorporating a redox system. Specifically, the proposed carbon dioxide rechargeable battery uses poly-1,4-anthraquinone and polyvinylferrocene in the negative and positive electrodes, respectively.

[0012] Examples of devices that utilize carbon dioxide include secondary batteries that not only utilize carbon dioxide but also concentrate it by adsorbing and desorbing carbon dioxide. Examples of such secondary batteries include the carbon dioxide adsorption battery described in Patent Document 4.

[0013] Patent Document 4 describes a carbon dioxide adsorption battery comprising a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte layer disposed between the positive electrode and the separator and between the negative electrode and the separator, respectively, wherein the positive electrode is a gas-permeable electrode, the electrolyte layer contains an electrolyte solution capable of dissolving carbon dioxide and a redox compound having an N-oxy radical group in the molecule, and the separator inhibits permeation of the redox compound and allows permeation of the electrolyte solution.

[0014] In a device capable of utilizing carbon dioxide, there is a demand for a device that can utilize carbon dioxide more effectively or that can separate carbon dioxide from a gas containing carbon dioxide in a short time while reducing power consumption. That is, in such a device capable of utilizing carbon dioxide, there is a demand for a device that can adsorb and desorb carbon dioxide in a short time even at a low voltage.

[0015] Japanese Patent Application Laid-Open No. 7-39752 Japanese Patent Application Laid-Open No. 2015-36128 Japanese Patent Application Laid-Open No. 2018-1131 International Publication No. 2022 / 185903

[0016] Aliza Khurram et al. , “Tailoring the Discharge Reaction in Li-CO2 Batteries through Corporation of CO2 Capture Chemistry”, Joule 2, 2649-2666, December 19, 2018 Sahag Voskian et al. , “Faradaiic electro-swing reactive adsorption for CO2 Capture”, Energy & Environmental Science, 2019, 12, 3530-3547

[0017] The present invention has been made in consideration of the above circumstances, and aims to provide a carbon dioxide adsorption battery that can adsorb carbon dioxide from a carbon dioxide-containing gas while charging and desorb the carbon dioxide during discharge in a short time even at a low voltage. Another aim of the present invention is to provide a charge / discharge device that includes the carbon dioxide adsorption battery.

[0018] One aspect of the present invention is a carbon dioxide adsorption battery comprising: a positive electrode; a negative electrode; a separator disposed between the positive electrode and the negative electrode; an electrolyte layer disposed between the negative electrode and the separator; and a flow path connected to the negative electrode; the electrolyte layer contains an electrolyte solution capable of dissolving carbon dioxide and a compound capable of adsorbing and desorbing carbon dioxide by an electrochemical reaction; the negative electrode is a gas-permeable electrode; and the positive electrode comprises a porous electrode containing the electrolyte solution.

[0019] These and other objects, features and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

[0020] Fig. 1 is a schematic cross-sectional view showing an example of the configuration of a carbon dioxide adsorption battery according to an embodiment of the present invention during charging. Fig. 2 is a schematic cross-sectional view showing an example of the configuration of a carbon dioxide adsorption battery according to an embodiment of the present invention during discharging. Fig. 3 is a schematic cross-sectional view showing another example of the configuration of a carbon dioxide adsorption battery according to an embodiment of the present invention during charging. Fig. 4 is a schematic cross-sectional view showing another example of the configuration of a carbon dioxide adsorption battery according to an embodiment of the present invention during discharging. Fig. 5 is a schematic view showing an example of the configuration of a charge / discharge device according to an embodiment of the present invention.

[0021] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these.

[0022] [Carbon Dioxide Adsorption Battery] As shown in FIGS. 1 and 2 , a carbon dioxide adsorption battery 10 according to a first embodiment of the present invention includes a positive electrode 11, a negative electrode 12, a separator 13 disposed between the positive electrode 11 and the negative electrode 12, an electrolyte layer 14 disposed between the negative electrode 12 and the separator 13, and a flow path 15 connected to the negative electrode 12. That is, in the carbon dioxide adsorption battery 10, the positive electrode 11 is disposed on one side of the separator 13, and the electrolyte layer 14 and the negative electrode 12 are disposed on the other side of the separator 13. The electrolyte layer 14 contains an electrolyte solution (first electrolyte solution) capable of dissolving carbon dioxide and a compound capable of adsorbing and desorbing carbon dioxide by an electrochemical reaction. The separator 13 inhibits permeation of the compound capable of adsorbing and desorbing carbon dioxide by an electrochemical reaction, but is permeable to the electrolyte solution. That is, the separator 13 is less permeable to the compound capable of adsorbing and desorbing carbon dioxide by an electrochemical reaction than the electrolyte solution. The separator 13 is preferably permeable to the electrolyte solution but impermeable to a compound capable of absorbing and desorbing carbon dioxide through the electrochemical reaction. The negative electrode 12 is a gas-permeable electrode. Specifically, the negative electrode 12 is permeable to gas flowing through the flow path 15 and can contact the electrolyte layer 14. The positive electrode 11 includes a porous electrode 11a containing an electrolyte solution (second electrolyte solution). The second electrolyte solution may be an electrolyte solution capable of dissolving carbon dioxide. The first electrolyte solution is the electrolyte solution contained in the electrolyte layer 14 described below, and the electrolyte solution (second electrolyte solution) contained in the porous electrode may be an electrolyte solution having the same composition as that of the electrolyte layer 14, or may be an electrolyte solution having a different composition. Here, a porous electrode is an electrode having a large specific surface area, specifically, a BET specific surface area of ​​10 m or less. ２ / g or more. The positive electrode 11 may be provided with a porous electrode 11a. For example, the positive electrode 11 may be an electrode made of the porous electrode 11a, or may be a positive electrode including a current collector 11b and the porous electrode 11a on the surface of the current collector 11b facing the separator 13, as shown in FIGS. 1 and 2 . The porous electrode 11a may contain an electrolyte solution, for example, an electrolyte solution obtained by permeating the separator 13 from the electrolyte solution contained in the electrolyte layer 14. The porous electrode 11a may not necessarily contain a compound capable of adsorbing and desorbing carbon dioxide through an electrochemical reaction, and does not need to contain such a compound. Furthermore, the porous electrode 11a is not limited to a compound capable of adsorbing and desorbing carbon dioxide through an electrochemical reaction, and does not need to contain a redox compound. In the carbon dioxide adsorption battery 10, the porous electrode 11a may not contain the redox compound, so it is preferable that the porous electrode 11a contain an electrolyte solution but not the redox compound. As described above, the positive electrode 11 is disposed on one side of the separator 13, and specifically, it is preferable that the porous electrode 11a is disposed in contact with the separator 13. As described above, the electrolyte layer 14 is disposed on the other side of the separator 13, and specifically, it is disposed in contact with the separator 13. The flow path 15 is not particularly limited as long as it is a flow path that allows gas to flow. The flow path 15 may also be provided with a valve 18 as necessary. Note that only a valve that is closed and restricts the flow of gas in the flow path 15 is illustrated as the valve 18. Specifically, the valve 18 is not illustrated in FIG. 1, and the valve 18 is illustrated in FIG. 2.

[0023] 1 and 2 are schematic cross-sectional views showing an example of the configuration of a carbon dioxide adsorption battery according to an embodiment of the present invention (the carbon dioxide adsorption battery 10), where FIG. 1 shows the carbon dioxide adsorption battery 10 during charging, and FIG. 2 shows the carbon dioxide adsorption battery 10 during discharging.

[0024] During charging of the carbon dioxide adsorption battery 10, as shown in FIG. 1 , a voltage is applied between the positive electrode 11 and the negative electrode 12 (between a pair of electrodes consisting of the positive electrode 11 and the negative electrode 12) so that the potential of the negative electrode 12 is lower than the potential of the positive electrode 11. Specifically, this voltage is a voltage that causes the compound contained in the electrolyte layer to be able to adsorb carbon dioxide through an electrochemical reaction. Charging of the carbon dioxide adsorption battery 10 is not particularly limited as long as a voltage can be applied as described above. Examples of charging of the carbon dioxide adsorption battery 10 include charging by providing a voltage application unit 16 that applies a voltage between a pair of electrodes consisting of the positive electrode 11 and the negative electrode 12 so that the potential of the negative electrode 12 is lower than the potential of the positive electrode 11, as shown in FIG. 1 . Discharging of the carbon dioxide adsorption battery 10 is not particularly limited, and examples thereof include discharging by electrically connecting the positive electrode 11 and the negative electrode 12. The carbon dioxide adsorption battery 10 may be discharged, for example, by providing a resistor 17 between a pair of electrodes consisting of the positive electrode 11 and the negative electrode 12, as shown in FIG.

[0025] As shown in FIG. 1 , in the carbon dioxide adsorption battery 10, first, when a gas containing carbon dioxide is circulated through the flow path 15, the gas passes through the negative electrode 12 and comes into contact with the electrolyte layer 14. As described above, the electrolyte layer 14 contains an electrolyte solution capable of dissolving carbon dioxide. Therefore, the carbon dioxide contained in the gas that comes into contact with the electrolyte layer 14 is dissolved in the electrolyte layer 14. The gas containing carbon dioxide is not particularly limited as long as it contains carbon dioxide, and examples thereof include gases containing carbon dioxide and nitrogen, and more specifically, air. As shown in FIG. 1 , when a voltage is applied between the positive electrode and the negative electrode of the carbon dioxide adsorption battery 10 as described above, the compound contained in the electrolyte layer 14 becomes capable of adsorbing carbon dioxide. Therefore, the carbon dioxide dissolved in the electrolyte solution contained in the electrolyte layer 14 is adsorbed by the compound contained in the electrolyte layer 14. When the carbon dioxide is adsorbed by the compound, the carbon dioxide adsorption battery 10 enters a charged state. Furthermore, since the carbon dioxide dissolved in the electrolyte is adsorbed to the compound, dissolution of carbon dioxide in the electrolyte is promoted, and the carbon dioxide adsorption battery 10 preferably progresses to a charged state. The compound with the adsorbed carbon dioxide is less likely to migrate to the positive electrode 11 (the porous electrode 11 a) side due to the separator 13. Therefore, even if the application of the voltage between the positive electrode 11 and the negative electrode 12 is stopped, the state in which carbon dioxide is adsorbed to the compound, i.e., the charged state, is preferably maintained as long as the positive electrode 11 and the negative electrode 12 are not electrically connected and discharged.

[0026] 2, when the positive electrode and the negative electrode are electrically connected and discharged, the compound is no longer in a state capable of adsorbing carbon dioxide due to an electrochemical reaction, and the carbon dioxide adsorbed to the compound is desorbed from the compound. Thus, in the carbon dioxide adsorption battery 10, carbon dioxide is released from the negative electrode 12 into the flow path 15 connected to the negative electrode 12 during discharge. The gas released from the carbon dioxide adsorption battery 10 during discharge is the gas adsorbed to the compound in the carbon dioxide adsorption battery 10 during charge, i.e., a gas mainly composed of carbon dioxide, and therefore has a very high carbon dioxide concentration. Note that, because carbon dioxide is released into the flow path 15, it is preferable that the valve 18 upstream of the flow path 15 be closed to prevent backflow of carbon dioxide.

[0027] For these reasons, the carbon dioxide adsorption battery 10 selectively adsorbs carbon dioxide from a gas containing carbon dioxide during charging, and releases the adsorbed carbon dioxide during discharging, thereby concentrating carbon dioxide.

[0028] Furthermore, in the carbon dioxide adsorption battery 10, charge compensation without the electrochemical reaction (specifically, charge compensation like that of a capacitor) is also performed in the positive electrode 11 by applying the voltage between the positive electrode 11 and the negative electrode 12. In addition, in the carbon dioxide adsorption battery 10, since the positive electrode 11 includes the porous electrode 11a, the positive electrode 11 has a large surface area, and this charge compensation can be suitably performed. This charge compensation has lower resistance than when the electrochemical reaction is involved, and can therefore contribute to driving at a low voltage (i.e., low power consumption).

[0029] As described above, the carbon dioxide adsorption battery 10 can be charged while adsorbing carbon dioxide from a gas containing carbon dioxide, and can desorb the carbon dioxide during discharge in a short time even at a low voltage.

[0030] The carbon dioxide adsorption battery 10 can be charged and discharged even if the adsorption and desorption of carbon dioxide as described above does not occur on the positive electrode 11 side. For this reason, the porous electrode 11a may contain the redox compound as described above, but does not need to contain the redox compound. Furthermore, not only the porous electrode 11a but also the positive electrode 11 side from the separator 13 may contain the redox compound, but does not need to contain the redox compound. Furthermore, since the positive electrode 11 side from the separator 13 does not need to contain the redox compound, the battery may contain an electrolyte solution but not the redox compound. Since the positive electrode 11 side from the separator 13 does not need to contain the redox compound, it is preferable that the content of the redox compound is small. Specifically, in the carbon dioxide adsorption battery 10, the capacity derived from the redox compound on the positive electrode 11 side of the separator 13 may be smaller than the capacity derived from the redox compound on the negative electrode 12 side of the separator 13. That is, it is preferable that the capacity derived from the redox compound present on the positive electrode 11 side of the separator 13 is smaller than the capacity derived from the redox compound present on the negative electrode 12 side of the separator 13. More specifically, the capacity derived from the redox compound on the positive electrode 11 side of the separator 13 is preferably 0 to 20%, more preferably 0 to 10%, even more preferably 0 to 5%, even more preferably 0 to 3%, and particularly preferably 0 to 1% of the capacity derived from the redox compound on the negative electrode 12 side of the separator 13. Thus, the carbon dioxide adsorption battery 10 can be charged while adsorbing carbon dioxide from a gas containing carbon dioxide and can desorb the carbon dioxide during discharge, even if the redox compound is contained in the area between the separator 13 and the positive electrode 11 in an amount that satisfies the capacity relationship, or even if the redox compound is not contained. Meanwhile, since the electrolyte layer 14 contains a compound that can adsorb and desorb carbon dioxide through an electrochemical reaction as described above, the carbon dioxide adsorption battery 10 contains a redox compound.That is, the carbon dioxide adsorption battery 10 contains a redox compound, which is a compound capable of adsorbing and desorbing carbon dioxide through an electrochemical reaction, at least in the electrolyte layer 14. Therefore, the carbon dioxide adsorption battery 10 preferably contains the redox compound on the negative electrode 12 side of the separator 13, in an amount that satisfies the capacity relationship. Furthermore, examples of the redox compound include compounds that can adsorb and desorb carbon dioxide through an electrochemical reaction, but are not particularly limited as long as they react by transferring electrons in a chemical reaction.

[0031] Here, the capacity derived from the redox compound on the negative electrode 12 side of the separator 13 refers to, for example, the capacity derived from the redox compound present on the negative electrode 12 side of the separator 13, and is the capacity generated when the redox compound present on the negative electrode 12 side of the separator 13 accepts electrons to become reduced, and the positive electrode 11 releases electrons. Furthermore, the redox compound present on the negative electrode 12 side of the separator 13 refers to all of the redox compounds present on the negative electrode 12 side of the separator 13, specifically, in the case of the carbon dioxide adsorption battery 10 shown in FIG. 1 , all of the redox compounds present on the left side of the separator 13. More specifically, the redox compound present on the negative electrode 12 side of the separator 13 refers to the sum of the redox compounds present inside the negative electrode 12 and in regions between the separator 13 and the negative electrode 12, such as the electrolyte layer 14. The capacity derived from the redox compound on the negative electrode 12 side of the separator 13 can be determined from the type and amount of the redox compound present on the negative electrode 12 side of the separator 13 .

[0032] The capacity derived from the redox compound on the positive electrode 11 side of the separator 13 is, for example, the capacity derived from the redox compound present on the positive electrode 11 side of the separator 13, and is the capacity generated when the redox compound present on the positive electrode 11 side of the separator 13 releases electrons to become oxidized, and the negative electrode 12 side accepts electrons. The redox compound present on the positive electrode 11 side of the separator 13 refers to all of the redox compounds present on the positive electrode 11 side of the separator 13. Specifically, in the case of the carbon dioxide adsorption battery 10 shown in FIG. 1 , for example, all of the redox compounds present on the right side of the separator 13. The redox compound present on the positive electrode 11 side of the separator 13 more specifically refers to the sum of the redox compounds present inside the positive electrode 11 (inside the porous electrode 11a and inside the current collector 11b) and in the region between the separator 13 and the positive electrode 11. The capacity derived from the redox compound on the positive electrode 11 side of the separator 13 can be determined from the type and amount of the redox compound present on the positive electrode 11 side of the separator 13 .

[0033] (Negative Electrode) The negative electrode 12 is not particularly limited as long as it is a gas-permeable electrode. That is, the negative electrode 12 may be a conductive material that is permeable to gases such as carbon dioxide and allows current to flow through the electrolyte layer 14 in contact with the negative electrode 12. Furthermore, the negative electrode 12 is preferably a porous material that has conductivity sufficient to not impede electron transfer, is capable of storing charge, has excellent breathability, and has a large gas contact area. Specific examples of the negative electrode 12 include electrodes made of porous conductive materials and electrodes made of porous materials containing conductive materials. Examples of the porous conductive material include porous metal layers, porous materials containing metal fibers, porous materials containing conductive fibers, porous materials containing carbon as a primary component, and porous materials made of carbon. Examples of the carbon include graphite, carbon nanotubes, activated carbon such as activated carbon fibers, and carbonaceous materials such as carbon fibers. The carbon-containing porous body is preferably a cloth- or felt-like carbonaceous material. For example, a cloth- or felt-like carbonaceous material containing the carbonaceous material and a resin can be used. Examples of the resin include styrene-butadiene rubber and carboxymethyl cellulose. Examples of the metal fiber-containing porous body include woven fabrics containing metal fibers, knitted fabrics containing metal fibers, and braided fabrics containing metal fibers. Examples of the conductive fiber-containing porous body include woven fabrics containing conductive fibers, knitted fabrics containing conductive fibers, and braided fabrics containing conductive fibers. Examples of the conductive fiber include metal-coated fibers. Examples of the coating method include plating. Examples of the conductive fiber include plated fibers. The porous conductive material may be used alone or in combination of two or more. That is, the negative electrode 12 may be an electrode composed of a single conductive material from these porous conductive materials, or an electrode composed of a combination of two or more conductive materials. Furthermore, examples of the conductive material contained in the porous body include metal fibers, conductive fibers, metal particles, conductive ceramics, graphite, carbon nanotubes, activated carbon such as activated carbon fibers, and carbonaceous materials such as carbon fibers.Examples of the metal fibers and metal particles include those containing copper and silver. The porous body containing the metal fibers may be a porous conductive material. Furthermore, the conductive material is preferably graphite, carbon nanotubes, carbon black such as acetylene black, activated carbon, or carbon fiber. From the viewpoints of corrosion resistance and specific surface area, activated carbon such as activated carbon fiber is more preferable. The porous metal layer is a metal layer having a large number of pores formed therein. Furthermore, the porous metal layer preferably has the pores formed throughout the entire metal layer in terms of excellent breathability. The method for obtaining the porous metal layer is not particularly limited as long as it involves subjecting a metal layer without pores (the metal layer before the pores are formed) to a treatment to form a large number of pores (a method for making the metal layer porous). Examples of such methods include physical methods such as cutting, polishing, and sandblasting, and chemical methods such as electrolytic etching or electroless etching using an etchant such as an acid or base. Furthermore, the method for making the metal layer porous may be performed alone or in combination of two or more of the above methods. In addition, as a method for making the porous layer, a chemical method is preferable in order to make the formed pores (micropores) denser (to form denser pores) from the viewpoint of increasing the surface area. The material of the metal layer is not particularly limited, and examples thereof include aluminum, copper, silver, gold, iron, titanium, molybdenum, tungsten, nickel, and alloys thereof. Among these, aluminum is preferable as the material of the metal layer from the viewpoint of cost and processability. Furthermore, the metal layer before the pores are formed is preferably so-called aluminum foil. The conductive material may be used alone or in combination of two or more. Furthermore, carbon-based electrodes using activated carbon or carbon fiber, and highly porosity electrodes using needle-shaped conductive materials are preferable as the negative electrode 12. Specific examples of the negative electrode 12 include carbon sheets, carbon cloths, and carbon paper.Among the above-mentioned electrodes, the negative electrode 12 is preferably an electrode made of a conductive material containing at least one selected from the group consisting of metal fibers, conductive fibers, metal particles, conductive ceramics, graphite, carbon nanotubes, activated carbon, and carbon fibers. Such an electrode is considered to not only more suitably apply a voltage between the negative electrode 12 and the positive electrode 11, but also more suitably allow carbon dioxide to permeate. Therefore, by using such an electrode as the negative electrode 12, a carbon dioxide adsorption battery can be obtained that can more suitably adsorb carbon dioxide from a carbon dioxide-containing gas during charging and more suitably release carbon dioxide during discharging.

[0034] The negative electrode 12 may further include a current collector. That is, the negative electrode 12 may be made of the porous body, or may include the porous body and the current collector. The current collector is not particularly limited as long as it does not hinder the gas permeation. For example, the current collector may be made of a conductive material and have openings to the extent that the gas permeation is not hindered. More specifically, the current collector may be made of a metal such as mesh metal, punched metal, or expanded metal, or may be a woven or nonwoven fabric made of natural or synthetic fibers plated to provide conductivity. Examples of metals that can be used as the current collector include stainless steel, iron, nickel, titanium, and copper.

[0035] In an electrode including the porous body and the current collector, the porous body and the current collector are preferably integrated, and the method for integration is not particularly limited. The integrated porous body and the current collector may be partially integrated using, for example, ultrasonic welding or plasma welding to ensure electrical conductivity. The integrated porous body and the current collector may also be electrically conductive by interposing a conductive material, such as a conductive adhesive, between the porous body and the current collector. The conductive material is not particularly limited, and examples of the conductive material include dispersed metal particles such as silver, gold, and nickel, carbon-based conductive materials, and conductive polymers.

[0036] The specific surface area of ​​the negative electrode 12 is not particularly limited, but for example, the BET specific surface area is 1 m ２ / g or more, and ２ / g or more is more preferable, and 500m ２ The BET specific surface area of ​​the negative electrode 12 is preferably large from the viewpoint of gas permeability (air permeability). ２ / g or less, and ２ / g or less is more preferable, and 2000m ２ Therefore, the BET specific surface area of ​​the negative electrode 12 is preferably 1 to 3000 m / g. ２ / g, and 100 to 2500m ２ / g, and more preferably 500 to 2000m ２ / g is more preferable. If the BET specific surface area of ​​the negative electrode 12 is too small, gas permeability (air permeability) tends to decrease, and carbon dioxide permeation tends to be hindered. Furthermore, if the BET specific surface area of ​​the negative electrode 12 is too large, the strength of the electrode tends to be insufficient. For these reasons, if the BET specific surface area of ​​the negative electrode 12 is within the above range, carbon dioxide adsorption and desorption can be achieved over a long period of time, and the negative electrode 12 can be used as a carbon dioxide battery over a long period of time. The BET specific surface area is a specific surface area measured by the BET method and can be measured by a known method. Examples of methods for measuring the BET specific surface area include a method of measuring a nitrogen adsorption isotherm and calculating the BET specific surface area from the obtained adsorption isotherm, and more specifically, a method of measuring the specific surface area of ​​a powder (solid) by gas adsorption in accordance with JIS Z8830:2013, and the like.

[0037] As described above, the negative electrode 12 is a conductive member that can pass current to the electrolyte layer 14 in contact with the negative electrode 12, and the smaller its surface resistance is, the more preferable it is, for example, preferably 1 kΩ / sq or less, and more preferably 200 Ω / sq or less. Furthermore, the smaller the surface resistance of the negative electrode 12 is, the more preferable it is. In practice, the surface resistance is limited to 1 Ω / sq, and is often approximately 10 Ω / sq or more. Therefore, the surface resistance of the negative electrode 12 is preferably 1 Ω / sq to 1 kΩ / sq, and more preferably 10 to 200 Ω / sq. An electrode with such a surface resistance value can favorably pass current to the electrolyte layer 14, and can favorably separate carbon dioxide.

[0038] The thickness of the negative electrode 12 is not particularly limited, but is preferably a thickness that can adsorb carbon dioxide and suitably prevent leakage of the electrolyte. The thickness of the negative electrode 12 is preferably, for example, 20 μm to 10 mm, and more preferably 50 μm to 5 mm. If the negative electrode 12 is too thin, the strength of the electrode tends to be insufficient. Furthermore, if the negative electrode 12 is too thick, the gas permeability (breathability) tends to decrease, and the permeation of carbon dioxide tends to be inhibited. For these reasons, if the thickness of the negative electrode 12 is within the above range, carbon dioxide separation can be achieved for a long period of time.

[0039] (Positive Electrode) The positive electrode 11 may include a porous electrode 11a containing an electrolyte solution. For example, the positive electrode 11 may be an electrode composed of the porous electrode 11a, or may be a positive electrode including a current collector 11b and the porous electrode 11a on the surface of the current collector 11b facing the separator 13, as shown in FIGS. 1 and 2 . The positive electrode 11 may also include a layer other than the porous electrode 11a and the current collector 11b for the purpose of maintaining strength, etc. The porous electrode 11a contains an electrolyte solution. Examples of the electrolyte solution include the electrolyte solution contained in the electrolyte layer 14, and examples include the electrolyte solution obtained by permeating the electrolyte solution contained in the electrolyte layer 14 through the separator 13.

[0040] The porous electrode 11a is not particularly limited as long as it can suitably perform charge compensation without electrochemical reaction when the voltage is applied to the positive electrode 11. Examples of the porous electrode 11a include an electrode capable of adsorbing anionic species derived from the electrolyte contained in the electrolyte solution. That is, the porous electrode 11a may be an electrode made of a porous conductive material that is porous, capable of adsorbing anionic species derived from the electrolyte, and capable of passing current. Furthermore, the porous electrode 11a is preferably a porous body that has conductivity sufficient to not inhibit electron transfer, can store charge, and has a large contact area with the electrolyte solution. Examples of the porous electrode 11a include an electrode made of the same material as the negative electrode 12. More specifically, examples of the porous electrode 11a include an electrode made of a porous material containing a conductive material and an electrode made of a porous material containing a conductive material. Examples of the porous conductive material include a porous body containing conductive fibers, a porous body containing carbon as a main component, and a porous body made of carbon. Examples of the carbon include carbonaceous materials such as graphite, carbon nanotubes, carbon black such as acetylene black, activated carbon such as activated carbon fiber, and carbon fibers. The carbon-containing porous body is preferably a cloth- or felt-like carbonaceous material, such as a cloth- or felt-like material containing the carbonaceous material and a resin. Examples of the resin include styrene-butadiene rubber and carboxymethyl cellulose. Examples of the porous body containing conductive fibers include woven fabrics containing conductive fibers, knitted fabrics containing conductive fibers, and braided fabrics containing conductive fibers. Examples of the conductive fibers include fibers coated with metal. Examples of the coating method include plating. Examples of the conductive fibers include plated fibers. The porous conductive materials may be used alone or in combination of two or more. That is, the porous electrode 11a may be an electrode composed of a single porous conductive material or a combination of two or more conductive materials.Examples of conductive materials contained in the porous body include metal fibers, conductive fibers, metal particles, conductive ceramics, graphite, carbon nanotubes, activated carbon such as activated carbon fibers, and carbonaceous materials such as carbon fibers. Examples of the metal fibers and metal particles include those containing copper and silver. The porous body containing the metal fibers may be a porous conductive material. The conductive material is preferably graphite, carbon nanotubes, carbon black such as acetylene black, activated carbon such as activated carbon fibers or activated carbon powder, or a carbonaceous material such as carbon fibers. From the viewpoints of corrosion resistance and specific surface area, activated carbon such as activated carbon fibers or activated carbon powder is more preferable. The conductive materials may be used alone or in combination of two or more. The porous electrode 11a is preferably a carbon-based electrode using activated carbon or carbon fibers, or a highly porosity electrode using a needle-shaped conductive material. Specific examples of the porous electrode 11a include carbon sheets, carbon cloth, and carbon paper. Among the electrodes exemplified above, the porous electrode 11a is preferably an electrode made of a porous material containing at least one selected from the group consisting of conductive ceramics, graphite, carbon nanotubes, activated carbon, and carbon fibers. A positive electrode 11 including such a porous electrode 11a is considered to not only more suitably apply a voltage between the positive electrode 11 and the negative electrode 12, but also more suitably perform charge compensation without electrochemical reaction. Therefore, when the positive electrode 11 includes such a porous electrode 11a, a carbon dioxide adsorption battery can be obtained that can efficiently adsorb carbon dioxide from a carbon dioxide-containing gas during charging and desorb the carbon dioxide during discharge, and can also be operated at a lower voltage (i.e., lower power consumption).

[0041] Since the porous electrode 11a is porous, it can adsorb a large amount of anionic species, and therefore can be driven at a low voltage. The larger the specific surface area of ​​the porous electrode 11a, the lower the voltage at which it can be driven. That is, the larger the specific surface area of ​​the porous electrode 11a, the greater the amount of anionic species adsorbed, and therefore it can be driven at a lower voltage. From these facts, it is assumed that the specific surface area of ​​the porous electrode 11a is, for example, 10 m2 in terms of BET specific surface area. ２ / g or more, and ２ / g or more, and ２ / g or more is more preferable, and 300m ２ / g or more is more preferable, and 500m ２ / g or more is particularly preferred, and ２ On the other hand, if the specific surface area of ​​the porous electrode 11a is too large, it may adversely affect the strength of the positive electrode 11. For this reason, the BET specific surface area of ​​the porous electrode 11a is preferably 3000 m / g or more. ２ / g or less, and ２ / g or less is more preferable, and 2300m ２ Therefore, the BET specific surface area of ​​the porous electrode 11a is preferably 10 to 3000 m / g. ２ / g, and 50 to 3000m ２ / g, and more preferably 100 to 3000m ２ / g, and more preferably 300 to 2500m ２ / g, and 500 to 2300m ２ / g, and 800 to 2300m ２ / g. In addition, the BET specific surface area of ​​the porous electrode 11a is preferably larger than the BET specific surface area of ​​the negative electrode 12. When the current collector 11b is provided as the positive electrode 11, it is more preferable that the BET specific surface area of ​​the porous electrode 11a is larger than the BET specific surface area of ​​the negative electrode 12, because there is less need to consider relationships such as strength. The BET specific surface area is a specific surface area measured by the BET method and can be measured by a known method. Examples of methods for measuring the BET specific surface area include a method of measuring a nitrogen adsorption isotherm and calculating the BET specific surface area from the obtained adsorption isotherm, and more specifically, a method for measuring the specific surface area of ​​a powder (solid) by gas adsorption in accordance with JIS Z8830:2013, and the like.

[0042] The average pore diameter of the porous electrode 11a is preferably less than 50 nm, more preferably 20 nm or less, even more preferably 10 nm or less, even more preferably 5.0 nm or less, and particularly preferably 3.0 nm or less. The average pore diameter of the porous electrode 11a is preferably 0.1 nm or more, more preferably 0.5 nm or more, even more preferably 1.0 nm or more, and particularly preferably 1.5 nm or more. Therefore, the average pore diameter of the porous electrode 11a is preferably 0.1 to 50 nm, more preferably 0.5 to 20 nm, even more preferably 0.5 to 10 nm, even more preferably 1.0 to 5.0 nm, and particularly preferably 1.5 to 3.0 nm. The average pore diameter can be calculated, for example, from the BET specific surface area and the total pore volume obtained from the nitrogen adsorption isotherm, using the following formula, assuming that the pores are cylindrical: Average pore diameter (nm) = 4 × total pore volume (nm ３ / g) / specific surface area (nm ２ / g)

[0043] However, the method for measuring the average pore diameter is suitable for pores of 50 nm or less. ３ In an electrode having a pore size of 50 nm or less, i.e., an electrode having very few pores of 50 nm or less, most of the pores are considered to be interparticle or interfiber gaps, and therefore the average pore size can be considered to be 50 nm or more.

[0044] The surface resistance of the porous electrode 11a is preferably as small as possible, for example, 1 kΩ / sq or less is preferable, and 200 Ω / sq or less is more preferable. Although the surface resistance of the porous electrode 11a is preferably as small as possible, in practice, the limit is 1 Ω / sq, and it is often approximately 10 Ω / sq or more. Therefore, the surface resistance of the porous electrode 11a is preferably 1 Ω / sq to 1 kΩ / sq, and more preferably 10 to 200 Ω / sq.

[0045] The thickness of the porous electrode 11a is not particularly limited, but is preferably a thickness that can adsorb anionic species derived from the electrolyte and suitably prevent leakage of the electrolyte. The thickness of the porous electrode 11a is, for example, preferably 20 μm to 10 mm, more preferably 50 μm to 5 mm. If the porous electrode 11a is too thin, the strength of the electrode tends to be insufficient.

[0046] As described above, the positive electrode 11 may include a current collector 11b. The current collector 11b is not particularly limited as long as it is made of a conductive material, and examples thereof include the same current collector as that included in the negative electrode 12. Examples of the current collector include those made of metals such as metal foil, mesh metal, punched metal, and expanded metal. Examples of metals that can be used as the current collector include stainless steel, iron, nickel, titanium, and copper.

[0047] The thickness of the positive electrode 11 is not particularly limited, but is preferably a thickness that can suitably prevent leakage of the electrolyte. The thickness of the positive electrode 11 is, for example, preferably 20 μm to 10 mm, and more preferably 50 μm to 5 mm.

[0048] In the positive electrode 11 including the current collector 11b, the porous electrode 11a and the current collector 11b are preferably integrated. The integration method is not particularly limited, and examples include methods similar to those used to integrate the porous body and current collector in the negative electrode 12. Specifically, the integrated porous electrode 11a and the current collector 11b may be integrated by, for example, ultrasonic welding or plasma welding, partially integrating the porous electrode 11a and the current collector 11b to ensure conductivity. The integrated porous electrode 11a and the current collector 11b may also be imparted with conductivity by interposing a conductive material, such as a conductive adhesive, between the porous electrode 11a and the current collector 11b. The conductive material is not particularly limited, and examples thereof include dispersed metal particles such as silver, gold, and nickel, carbon-based conductive materials, and conductive polymers.

[0049] (Electrolyte Layer) The electrolyte layer 14 is not particularly limited as long as it contains an electrolytic solution capable of dissolving carbon dioxide and a compound capable of absorbing and desorbing carbon dioxide through an electrochemical reaction. As described above, the electrolyte layer 14 is a carbon dioxide separator that contributes to the separation of carbon dioxide by adsorption and release of carbon dioxide.

[0050] Examples of the compound contained in the electrolyte layer 14 include compounds that adsorb carbon dioxide by electrolytic reduction and desorb carbon dioxide by electrolytic oxidation. In addition, examples of the compound include the following compounds in the carbon dioxide adsorption battery 10. Specific examples include compounds that adsorb carbon dioxide when the potential between the positive electrode 11 and the negative electrode 12 is relatively low and accepts electrons, and desorb carbon dioxide when the potential is relatively high and supplies electrons. Examples of the compound include compounds that have at least one of a quinone group and an N-oxy radical group in the molecule. Specifically, examples of the compound include compounds that have a quinone group in the molecule, compounds that have an N-oxy radical group in the molecule, and compounds that have both a quinone group and an N-oxy radical group in the molecule. Examples of the compound that has a quinone group in the molecule include benzoquinone, naphthoquinone, and anthraquinone. Furthermore, examples of compounds having an N-oxy radical group in the molecule include compounds in which two quaternary carbons are bonded to the N-oxy radical group. Among these, from the viewpoint of durability, compounds having an N-oxy radical group in the molecule are preferred, and compounds in which two quaternary carbons are bonded to the N-oxy radical group are more preferred. It is believed that compounds in which two quaternary carbons are bonded to the N-oxy radical group can inhibit the N-oxy radical group from abstracting a hydrogen radical from the carbon adjacent to the N-oxy radical group, thereby preventing the decomposition of the N-oxy radical group. Therefore, it is believed that the compound can more effectively adsorb and desorb carbon dioxide, and the carbon dioxide adsorption battery can more effectively adsorb carbon dioxide from a gas containing carbon dioxide and maintain a charged state.

[0051] The compound is preferably nonvolatile. The compound is converted into an oxyanion group, to which carbon dioxide is bound, by, for example, applying a voltage between the positive electrode 11 and the negative electrode 12 by the voltage application unit 16. Specifically, in the case of a quinone group, the quinone group is reduced to form an oxyanion group, and in the case of an N-oxyanion group, the N-oxyanion group is reduced to form an N-oxyanion group, to which carbon dioxide is bound. Furthermore, when the carbon dioxide adsorption battery 10 is discharged, carbon dioxide is released to form an oxyanion group, and this oxyanion group is oxidized. Specifically, an oxyanion group generated by the reduction of a quinone group is oxidized back to a quinone group, and an N-oxyanion group generated by the reduction of an N-oxyanion group is oxidized back to an N-oxyanion group. The compound is thus a compound in which the quinone group, N-oxy radical group, etc. change through oxidation-reduction. More specifically, the compound having a quinone group undergoes electrolytic reduction as shown in the following formula (4) during charging, thereby adsorbing carbon dioxide as shown in the following formula (5). Then, the compound having a quinone group undergoes electrolytic oxidation as shown in the following formula (6) during discharging, thereby desorbing the adsorbed carbon dioxide as shown in the following formula (7). The compound having an N-oxy radical group undergoes electrolytic reduction as shown in the following formula (8) during charging, thereby adsorbing carbon dioxide as shown in the following formula (9). The compound having an N-oxy radical group undergoes electrolytic oxidation as shown in the following formula (10) during discharging, thereby desorbing the adsorbed carbon dioxide as shown in the following formula (11). When the compound has the quinone group and an N-oxy radical group, during charging, it undergoes electrolytic reduction as shown in the following formulas (4) and (8), thereby adsorbing carbon dioxide as shown in the following formulas (5) and (9). During discharge, the compound is electrolytically oxidized as shown in the following formulas (6) and (10), and the adsorbed carbon dioxide is desorbed as shown in the following formulas (7) and (11).

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060] The compound contained in the electrolyte layer 14 binds carbon dioxide dissolved in the electrolyte solution to the oxyanion groups (oxyanion groups generated by reduction of quinone groups and N-oxyanion groups generated by reduction of N-oxyanion groups) on the side closer to the negative electrode 12, which is the electrode with a lower potential, thereby promoting the dissolution of carbon dioxide into the electrolyte solution. Therefore, when the carbon dioxide adsorption battery 10 is charged, carbon dioxide is taken in from the negative electrode 12 side and adsorbed into the electrolyte layer 14. In other words, the compound is electrolytically reduced to adsorb carbon dioxide. Therefore, when carbon dioxide is adsorbed by the compound, the carbon dioxide adsorption battery 10 enters a charged state.

[0061] The separator 13 is permeable to the electrolyte but inhibits the permeation of compounds capable of absorbing and desorbing carbon dioxide through the electrochemical reaction, such as the compound. That is, the separator 13 is less permeable to the compound than the electrolyte. Therefore, redox compounds formed by the reduction of quinone groups and N-oxyanion groups to form oxyanion groups (oxyanion groups generated by the reduction of quinone groups and N-oxyanion groups reduced from N-oxyanion groups) and redox compounds bound to carbon dioxide are less likely to permeate the separator 13. Therefore, even after charging is stopped, as long as discharging is not performed, these redox compounds are less likely to permeate the separator 13, allowing the carbon dioxide adsorption battery 10 to maintain a charged state.

[0062] Next, when the charged carbon dioxide adsorption battery 10 is discharged, carbon dioxide is desorbed from the compound in the electrolyte layer 14, and the compound returns to the state before electrical reduction. Therefore, when the carbon dioxide adsorption battery 10 is discharged, it can release carbon dioxide from the electrode side that took in carbon dioxide.

[0063] As described above, by including the compound in the electrolyte layer 14, the carbon dioxide adsorption battery 10 can perform charging while adsorbing carbon dioxide from a gas containing carbon dioxide and desorbing the carbon dioxide during discharge in a short time even at a low voltage, without including the compound on the positive electrode 11 side, for example, on the porous electrode 11a provided on the positive electrode 11. Since the compound does not need to be included on the positive electrode 11 side, for example, on the porous electrode 11a provided on the positive electrode 11, there is also the advantage that the number of components can be reduced.

[0064] The electrolyte solution is not particularly limited as long as it is capable of dissolving carbon dioxide, and may be an electrolyte solution containing an electrolyte and a solvent, or an electrolyte solution containing an ionic liquid. Note that an electrolyte solution capable of dissolving carbon dioxide may be any solution other than one in which carbon dioxide is not dissolved; that is, any electrolyte solution in which even a small amount of carbon dioxide dissolves is sufficient, and high solubility is not required. This is believed to be due to the following. As described above, in the carbon dioxide adsorption battery according to this embodiment, the adsorption and release of carbon dioxide is believed to proceed through a mechanism in which carbon dioxide is taken into the electrolyte layer during charging by binding and desorption of carbon dioxide to the compound, and carbon dioxide is released from the electrolyte layer 14 during discharge. Therefore, it is believed that the adsorption and release of carbon dioxide proceeds if even a small amount of carbon dioxide dissolves in the electrolyte solution contained in the electrolyte layer.

[0065] As described above, the electrolyte solution is not particularly limited as long as it is an electrolyte solution capable of dissolving carbon dioxide, but is preferably non-volatile. As described above, the electrolyte solution may be an electrolyte solution containing an electrolyte and a solvent, or an electrolyte solution containing an ionic liquid, but is preferably non-volatile and usable as an electrolyte solution. Specifically, the electrolyte solution is preferably an ionic liquid.

[0066] The solvent is preferably an electrochemically stable compound with a wide potential window, and may be either an aqueous solvent or an organic solvent. Examples of the solvent include water, carbonate compounds, ester compounds, ether compounds, heterocyclic compounds, nitrile compounds, and aprotic polar compounds. Examples of the carbonate compounds include dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, and propylene carbonate. Examples of the ester compounds include methyl acetate, methyl propionate, and γ-butyrolactone. Examples of the ether compounds include diethyl ether, 1,2-dimethoxyethane, 1,3-dioxosilane, tetrahydrofuran, and 2-methyl-tetrahydrofuran. Examples of the heterocyclic compounds include 3-methyl-2-oxazolidinone and 2-methylpyrrolidone. Examples of the nitrile compounds include acetonitrile, methoxyacetonitrile, propionitrile, 3-methoxypropionitrile, and valeric acid nitrile. Examples of the aprotic polar compound include sulfolane, dimethyl sulfoxide, and dimethylformamide. As the solvent, the exemplified solvents may be used alone or in combination of two or more. Among the exemplified solvents, preferred solvents include carbonate compounds such as ethylene carbonate and propylene carbonate, ester compounds such as γ-butyrolactone, heterocyclic compounds such as 3-methyl-2-oxazolidinone and 2-methylpyrrolidone, and nitrile compounds such as acetonitrile, methoxyacetonitrile, propionitrile, 3-methoxypropionitrile, and valeric acid nitrile. When two or more solvents are used in combination, water is preferred from the viewpoint of dissolving carbon dioxide.

[0067] The electrolyte is not particularly limited, and examples thereof include quaternary ammonium salts, inorganic salts, and hydroxides. Examples of the quaternary ammonium salts include tetramethylammonium tetrafluoroborate, tetra-n-ethylammonium tetrafluoroborate, tetra-n-propylammonium tetrafluoroborate, tetra-n-butylammonium tetrafluoroborate, n-hexadecyltrimethylammonium tetrafluoroborate, tetra-n-hexadecylammonium tetrafluoroborate, tetra-n-octylammonium tetrafluoroborate, tetra-n-ethylammonium perchlorate, tetra-n-butylammonium perchlorate, and tetraoctadecylammonium perchlorate. Examples of the inorganic salts include lithium perchlorate, sodium perchlorate, potassium perchlorate, sodium acetate, potassium acetate, sodium nitrate, and potassium nitrate. Examples of the hydroxides include sodium hydroxide and potassium hydroxide. Among the electrolytes exemplified above, the electrolyte is preferably tetramethylammonium tetrafluoroborate, tetra-n-ethylammonium tetrafluoroborate, tetra-n-propylammonium tetrafluoroborate, tetra-n-butylammonium tetrafluoroborate, n-hexadecyltrimethylammonium tetrafluoroborate, tetra-n-hexadecylammonium tetrafluoroborate, tetra-n-octylammonium tetrafluoroborate, tetra-n-ethylammonium perchlorate, tetra-n-butylammonium perchlorate, tetraoctadecylammonium perchlorate, lithium perchlorate, sodium perchlorate, sodium acetate, or potassium acetate. Furthermore, among these, the electrolyte is more preferably tetra-n-ethylammonium tetrafluoroborate, tetra-n-propylammonium tetrafluoroborate, tetra-n-butylammonium tetrafluoroborate, lithium perchlorate, or sodium perchlorate, and further preferably tetra-n-butylammonium tetrafluoroborate or lithium perchlorate.The electrolyte may also have a pH buffering ability by stabilizing carbonate ions or bicarbonate ions as a supporting salt. Specific examples of the electrolyte include sodium bicarbonate, sodium carbonate, acetic acid, and sodium acetate. The above-listed electrolytes may be used alone or in combination of two or more.

[0068] As described above, the electrolyte solution may be an electrolyte solution containing an ionic liquid (ionic liquid). When an ionic liquid is used as the electrolyte solution, the ionic liquid can have the functions of both an electrolyte and a solvent, as described above. Furthermore, the electrolyte solution may contain an ionic liquid, and may be a liquid containing an electrolyte in the ionic liquid, a liquid containing a solvent in the ionic liquid, a liquid containing an electrolyte and a solvent in the ionic liquid, or a liquid consisting of the ionic liquid. Furthermore, using an ionic liquid as the electrolyte solution is preferable because the ionic liquid is less likely to volatilize and has high flame retardancy.

[0069] The ionic liquid is not particularly limited as long as it is a known ionic liquid, and examples thereof include imidazolium-based ionic liquids, pyridine-based ionic liquids, alicyclic amine-based ionic liquids, and azonium amine-based ionic liquids. Examples of the ionic liquid include 1-methyl-3-octylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, and 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-decyl-3-methylimidazolium tetrafluoroborate, 1,3-dimethoxyimidazolium tetrafluoroborate, 1,3-diethoxyimidazolium tetrafluoroborate, 1-methyl-3-octylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-decyl-3-methylimidazolium hexafluorophosphate, 1,3-dimethoxyimidazolium hexafluorophosphate, 1,3-diethoxyimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide. Furthermore, among the ionic liquids exemplified above, 1-methyl-3-octylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonylimide), 1,3-dimethoxyimidazolium tetrafluoroborate, 1-methyl-3-octylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide are preferred as the ionic liquid.Moreover, as the ionic liquid, 1-methyl-3-octylimidazolium tetrafluoroborate, 1,3-dimethoxyimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonylimide), 1-butyl-3-methylimidazolium chloride, 1-methyl-3-octylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide are more preferable, and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonylimide), 1-butyl-3-methylimidazolium chloride, 1-methyl-3-octylimidazolium tetrafluoroborate, and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide are even more preferable.

[0070] The electrolyte layer 14 may be formed by gelling the electrolyte solution. Specifically, a gelling agent for gelling the electrolyte solution may be added, or a gelled electrolyte or polymer electrolyte may be used. Examples of the gelling agent include polymers, gelling agents that utilize techniques such as polymer crosslinking reactions, polymerizable polyfunctional monomers, and oil gelling agents. The gelled electrolyte and polymer electrolyte are not particularly limited as long as they can be used as a gelled electrolyte or polymer electrolyte. Examples include vinylidene fluoride polymers such as polyvinylidene fluoride and poly(vinylidene fluoride-co-hexafluoropropylene), acrylic acid polymers such as polyacrylic acid, acrylonitrile polymers such as polyacrylonitrile, polyether polymers such as polyethylene oxide, and compounds having an amide structure in their structure.

[0071] The compound, specifically, the compound having the N-oxy radical group, may be any of a compound represented by the following formula (1), a compound represented by the following formula (2), and a compound represented by the following formula (3), or a compound having a group obtained by eliminating one hydrogen atom from a compound represented by any of the following formulas (1) to (3). The compound having a group obtained by eliminating one hydrogen atom from a compound represented by any of the following formulas (1) to (3) may be any compound having the group, and may be a compound bonded to another low molecular weight compound or a high molecular weight compound.

[0072]

[0073]

[0074]

[0075] In formulas (1) to (3), Z is -CR ５ R ６ CR ７ R ８ -, -CR ９ R １０ CR １１ R １２ CR １３ R １４ -, - (CR １５ R １６ ) O-, -(CR １７ R １８ ) NR ２７ -, - (CR １９ R ２０ ) O (CR ２１ R ２２ ) - or - (CR ２３ R ２４ ) NR ２８ (CR ２５ R ２６ )-. R １ ~R ４ each independently represents a substituent, R １ and R ２ may be bonded to each other to form a ring, and R ３ and R ４ and may be bonded to each other to form a ring. ５ ~R ２８each independently represents a hydrogen atom or a substituent.

[0076] The R １ ~R ４ Preferably, at least one of the N-oxy radical groups is a substituent, more preferably two or more are substituents, and even more preferably all four are substituents. That is, the compound represented by formula (1) is preferably a compound in which two quaternary carbons are bonded to the N-oxy radical group. Furthermore, the compound is preferably a compound in which two quaternary carbons are bonded to the N-oxy radical group, or a compound having a group in which one hydrogen atom has been eliminated from this compound. It is believed that such a compound is more susceptible to oxidation-reduction by the N-oxy radical group, and that the compound can more suitably adsorb and release carbon dioxide. For this reason, by including such a compound in the electrolyte layer, a carbon dioxide adsorption battery can be obtained that can more suitably adsorb carbon dioxide from a carbon dioxide-containing gas during charging and more suitably release carbon dioxide during discharge.

[0077] Z in the compounds represented by the formulas (1) to (3) is —CR ５ R ６ CR ７ R ８ -, -CR ９ R １０ CR １１ R １２ CR １３ R １４ -, - (CR １９ R ２０ ) O (CR ２１ R ２２ )-, and -(CR ２３ R ２４ ) NR ２８ (CR ２５ R ２６ )- is preferred.

[0078] The R １ ~R ２８Examples of the substituent in R include a hydrocarbyl group having 1 to 30 carbon atoms, a hydrocarbyloxy group having 1 to 10 carbon atoms, a hydroxyl group, an amino group which may be substituted (an unsubstituted or substituted amino group), a carboxyl group, a thiol group, and a silyl group which may be substituted (an unsubstituted or substituted silyl group). １ ~R ２６ Among these, the substituents in R are preferably hydrocarbyl groups having 1 to 30 carbon atoms, hydroxy groups, and unsubstituted or substituted amino groups. ２７ , R ２８ The substituent in is preferably a hydrocarbyl group having 1 to 30 carbon atoms.

[0079] Here, "optionally substituted" includes both cases where the hydrogen atoms constituting the compound or group described immediately thereafter are unsubstituted and cases where some or all of the hydrogen atoms are substituted with substituents.

[0080] The hydrocarbyl group is not particularly limited and may be linear, branched, or cyclic. Examples of the hydrocarbyl group include a methyl group, an ethyl group, a 1-propyl group, a 2-propyl group, a 1-butyl group, a 2-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a 2-ethylhexyl group, a 3,7-dimethyloctyl group, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group, a norbornyl group, an ammonium ethyl group, a benzyl group, an α,α-dimethylbenzyl group, a 1-phenethyl group, a 2-phenethyl group, a vinyl group, a propenyl group, a butenyl group, an oleyl group, an eicosapentaenyl group, a docosahexaenyl group, a 2,2-diphenylvinyl group, a 1,2,2-triphenylmethyl ... Examples of such groups include a phenylvinyl group, a 2-phenyl-2-propenyl group, a phenyl group, a 2-tolyl group, a 4-tolyl group, a 4-trifluoromethylphenyl group, a 4-methoxyphenyl group, a 4-cyanophenyl group, a 2-biphenylyl group, a 3-biphenylyl group, a 4-biphenylyl group, a terphenylyl group, a 3,5-diphenylphenyl group, a 3,4-diphenylphenyl group, a pentaphenylphenyl group, a 4-(2,2-diphenylvinyl)phenyl group, a 4-(1,2,2-triphenylvinyl)phenyl group, a fluorenyl group, a 1-naphthyl group, a 2-naphthyl group, a 9-anthryl group, a 2-anthryl group, a 9-phenanthryl group, a 1-pyrenyl group, a chrysenyl group, a naphthacenyl group, and a coronyl group.Among these, examples of the hydrocarbyl group include a methyl group, an ethyl group, a 1-propyl group, a 2-propyl group, a 1-butyl group, a 2-butyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a 2-ethylhexyl group, a 3,7-dimethyloctyl group, a benzyl group, an α,α-dimethylbenzyl group, a 1-phenethyl group, a 2-phenethyl group, a vinyl group, a propenyl group, a butenyl group, an oleyl group, an eicosapentaenyl group, a docosahexaenyl group, a 2,2-diphenylvinyl group, a 1,2,2-triphenylvinyl group, a 2-phenyl-2-prop ... Preferred are a phenyl group, a phenyl group, a 2-tolyl group, a 4-tolyl group, a 4-trifluoromethylphenyl group, a 4-methoxyphenyl group, a 4-cyanophenyl group, a 2-biphenylyl group, a 3-biphenylyl group, a 4-biphenylyl group, a terphenylyl group, a 3,5-diphenylphenyl group, a 3,4-diphenylphenyl group, a pentaphenylphenyl group, a 4-(2,2-diphenylvinyl)phenyl group, a 4-(1,2,2-triphenylvinyl)phenyl group, a fluorenyl group, a 1-naphthyl group, a 2-naphthyl group, a 9-anthryl group, a 2-anthryl group, and a 9-phenanthryl group. Furthermore, among these, the hydrocarbyl group is more preferably a methyl group, an ethyl group, a 1-propyl group, a 2-propyl group, a 1-butyl group, a 2-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a 2-ethylhexyl group, a 3,7-dimethyloctyl group, a benzyl group, or a phenyl group, and even more preferably a methyl group, an ethyl group, a 1-propyl group, a 2-propyl group, a 1-butyl group, a 2-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, or a hexyl group.

[0081] The hydrocarbyloxy group is not particularly limited, and may be linear, branched, or cyclic. Examples of the hydrocarbyloxy group include a methoxy group, an ethoxy group, a 1-propyloxy group, a 2-propyloxy group, a 1-butoxy group, a 2-butoxy group, an isobutoxy group, a tert-butoxy group, a pentyloxy group, a hexyloxy group, an octyloxy group, a decyloxy group, a dodecyloxy group, a 2-ethylhexyloxy group, a 3,7-dimethyloctyloxy group, a cyclopropanoxy group, a cyclopentyloxy group, a cyclohexyloxy group, a 1-adamantyloxy group, a 2-adamantyloxy group, a norbornyloxy group, an ammoniumethoxy group, a trifluoromethoxy group, a benzyloxy group, an α,α-dimethylbenzyloxy group, a 2-phenethyloxy group, a 1-phenethyloxy group, a phenoxy group, an alkoxyphenoxy group, an alkylphenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, and a pentafluorophenyloxy group. Among these, the hydrocarbyloxy group is preferably a methoxy group, an ethoxy group, a 1-propyloxy group, a 2-propyloxy group, a 1-butoxy group, a 2-butoxy group, a tert-butoxy group, a pentyloxy group, a hexyloxy group, an octyloxy group, a decyloxy group, a dodecyloxy group, a 2-ethylhexyloxy group, or a 3,7-dimethyloctyloxy group. Furthermore, among these, the hydrocarbyloxy group is more preferably a methoxy group, an ethoxy group, a 1-propyloxy group, a 2-propyloxy group, a 1-butoxy group, a 2-butoxy group, an isobutoxy group, a tert-butoxy group, a pentyloxy group, or a hexyloxy group.

[0082] The amino group is not particularly limited, and may be linear, branched, or cyclic. Examples of the amino group include a methylamino group, an ethylamino group, a 1-propylamino group, a 2-propylamino group, a 1-butylamino group, a 2-butylamino group, an isobutylamino group, a tert-butylamino group, a pentylamino group, a hexylamino group, an octylamino group, a decylamino group, a dodecylamino group, a 2-ethylhexylamino group, a 3,7-dimethyloctylamino group, a cyclopropylamino group, a cyclopentylamino group, a cyclohexylamino group, a 1-adamantylamino group, a 2-adamantylamino group, a norbornylamino group, an ammoniumethylamino group, a trifluoromethylamino group, a benzylamino group, an α,α-dimethylbenzylamino group, a 2-phenethylamino group, a 1-phenethylamino group, a phenylamino group, an alkoxyphenylamino group, an alkylphenylamino group, a 1-naphthylamino group, a 2-naphthylamino group, and a pentafluorophenylamino group. Among these, the amino group is preferably a methylamino group, an ethylamino group, a 1-propylamino group, a 2-propylamino group, a 1-butylamino group, a 2-butylamino group, a tert-butylamino group, a pentylamino group, a hexylamino group, an octylamino group, a decylamino group, a dodecylamino group, a 2-ethylhexylamino group, or a 3,7-dimethyloctylamino group. Furthermore, the amino group is more preferably a methylamino group, an ethylamino group, a 1-propylamino group, a 2-propylamino group, a 1-butylamino group, a 2-butylamino group, an isobutylamino group, a tert-butylamino group, a pentylamino group, or a hexylamino group.

[0083] The silyl group is not particularly limited, and examples of the silyl group include a dimethylsilyl group, a diethylsilyl group, a diphenylsilyl group, a trimethylsilyl group, a triethylsilyl group, a t-butyldimethylsilyl group, a t-butyldiphenylsilyl group, and a tristrimethylsilyl group.

[0084] As described above, the compound represented by formula (1) is preferably a compound in which two quaternary carbons are bonded to the N-oxy radical group. It is believed that the bonding of a group with high steric hindrance to a site adjacent to the N-oxy radical group in this manner increases the stability of the radical and suppresses radical coupling. Therefore, it is believed that by including such a compound in the electrolyte layer, a carbon dioxide adsorption battery can be obtained that can more effectively adsorb carbon dioxide from a carbon dioxide-containing gas during charging and release carbon dioxide during discharge.

[0085] Examples of the compound represented by formula (1) include 1,4-di(1-oxy-2,2,6,6-tetramethyl-1-piperidin-4-yloxy)xylene, 4-acetamido-2,2,6,6-tetramethylpiperidine 1-oxyl, N,N-di-tert-butyl nitroxide radical, N,N-diphenyl nitroxide radical, N,N-dinaphthyl nitroxide radical, N,N-di-2-methylphenyl nitroxide radical, N,N-di-3-methylphenyl nitroxide radical, N,N-di-4-methylphenyl nitroxide radical, N , N-di-2-ethylphenyl nitroxide radical, N,N-di-2-propylphenyl nitroxide radical, N,N-di-2-butylphenyl nitroxide radical, N,N-di-2-pentylphenyl nitroxide radical, N,N-di-2-hexylphenyl nitroxide radical, N,N-di-2-isopropylphenyl nitroxide radical, N,N-di-2-isobutylphenyl nitroxide radical, N,N-di-2-sec-butylphenyl nitroxide radical, N,N-di-2-tert-butylphenyl nitroxide radical , N,N-di-4-tert-butylphenyl nitroxide radical, N,N-di-(3,5-di-tert-butyl)phenyl nitroxide radical, N,N-di-4-pyridyl nitroxide radical, N,N-di-4-pyridazyl nitroxide radical, poly(ethylene glycol)-bis-2,2,6,6-tetramethylpiperidinyloxy radical, N-phenyl-N-oxy-tert-butylamine, N-naphthyl-N-oxy-tert-butylamine, N-tert-butyl-N-oxy-2-quinoline, 2,2,6,6-tetramethyl piperidinyloxy radical (TEMPO), 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy radical, 4-amino-2,2,6,6-tetramethylpiperidinyloxy radical, 4-carboxy-2,2,6,6-tetramethylpiperidinyloxy radical, 4-methoxy-2,2,6,6-tetramethylpiperidinyloxy radical, 4-oxo-2,2,6,6-tetramethylpiperidinyloxy radical, 4-acetamido-2,2,6,6-tetramethylpiperidinyloxy radical, 4-octyloxy-2,2,6,Examples include a 6-tetramethylpiperidinyloxy radical, a 2,2,5,5-tetramethylpyrrolidine-oxy radical, a 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-oxy radical, a 3-carboxy-2,2,5,5-tetramethylpyrrolidine-oxy radical, a 2,2,6,6-tetramethylmorpholine-N-oxy radical, and a 2,2,6,6-tetramethylmorpholinepiperazine-N-oxy radical.

[0086] Examples of the compound represented by formula (2) include γ-dimethyl-butyrolactam-N-oxide, ε-dimethyl-valerolactam-N-oxide, 3,4-dihydroquinolin-2-one-N-oxide, 3,3-dimethylisoquinolin-1-one-N-oxide, 3,3-dimethyl-1H-indol-2(3H)-one-N-oxide, 3,3-dimethyl-isoindolin-1-one-N-oxide, and N-t-butylbenzoic acid-N-oxide.

[0087] Examples of the compound represented by formula (3) include 1α,2α-cyclohexanedicarboimide-N-oxyl, phthalimide-N-oxyl, 3-methyl-phthalimide-N-oxyl, 4-methyl-phthalimide-N-oxyl, 4-carboxy-phthalimide-N-oxyl, naphthalene-2,3-dicarboximide-N-oxyl, pyromellitimide-di-N-oxyl, trihydroxyiminocyanuric acid-N-oxyl, trihydroxyiminocyanuric acid-di-N-oxyl, and trihydroxyiminocyanuric acid-tri-N-oxyl.

[0088] As described above, the compound may be a polymeric compound, and examples thereof include compounds obtained by polymerizing a compound represented by any one of formulas (1) to (3). Examples of the polymeric compound include compounds obtained by polymerizing a monomer such as a 4-acryloyloxy-2,2,6,6-tetramethylpiperidinyloxy radical, a 4-methacryloyloxy-2,2,6,6-tetramethylpiperidinyloxy radical, a 3-acryloyloxy-2,2,6,6-tetramethylpyrrolidinyloxy radical, a 3-methacryloyloxy-2,2,6,6-tetramethylpyrrolidinyloxy radical, a 4-vinyloyloxy-2,2,6,6-tetramethylpiperidinyloxy radical, or a 4-vinyloyloxy-2,2,5,5-tetramethylpyrrolidinyloxy radical. The polymeric compound may be a compound obtained by polymerizing any one of the monomers alone, or may be a compound obtained by polymerizing two or more of the monomers in combination. The polymer compound may be a compound obtained by polymerizing the compound represented by formula (1), or may be a copolymer obtained by copolymerizing the compound with a copolymerizable monomer such as ethylene, propylene, butadiene, isoprene, styrene, vinyl acetate, etc. The copolymerizable monomer may be used alone or in combination of two or more thereof.

[0089] Among the above-exemplified compounds, 1,4-di(1-oxy-2,2,6,6-tetramethyl-1-piperidin-4-yloxy)xylene, 4-acetamido-2,2,6,6-tetramethylpiperidine 1-oxyl, and poly(4-methacryloyloxy-2,2,6,6-tetramethylpiperidinyloxy radical) are preferred. The compounds may be used alone or in combination of two or more.

[0090] The compound represented by any one of the formulas (1) to (3) may be a compound obtained by synthesis using a predetermined synthesis method, or may be a commercially available product. The synthesis method is not particularly limited as long as it is a synthesis method that can obtain a compound represented by any one of the formulas (1) to (3), and examples thereof include a method of nitroxidizing the amino group of a disubstituted amine compound.

[0091] Note that non-volatile means that the substance does not evaporate or does not evaporate immediately at room temperature and pressure. For example, in this specification, 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) is not non-volatile but volatile. Therefore, an indicator of non-volatility is, for example, a boiling point at normal pressure that is higher than 193°C, which is the boiling point of TEMPO, preferably 200°C or higher, and more preferably 220°C or higher. Furthermore, an indicator of non-volatility is, for example, a vapor pressure at 20°C that is lower than 0.4 hPa, which is the vapor pressure of TEMPO (20°C) (i.e., less than 0.4 hPa), and preferably lower than 0.2 hPa (i.e., less than 0.2 hPa).

[0092] Examples of compounds having a quinone group include compounds such as 1,4-benzoquinone, 1,4-naphthoquinone, 1,5-naphthoquinone, 1,8-naphthoquinone, 1,4-anthraquinone, 1,5-anthraquinone, 1,6-anthraquinone, and 5,10-anthraquinone, as well as polymers thereof such as poly-1,4-naphthoquinone, poly-1,5-naphthoquinone, poly-1,8-naphthoquinone, poly-1,4-anthraquinone, poly-1,5-anthraquinone, poly-1,6-anthraquinone, and poly-5,10-anthraquinone.

[0093] The electrolyte layer 14 may contain components other than the electrolytic solution and the compound. Examples of other components contained in the electrolyte layer 14 include polyethylene glycol, polyacrylate, polymethacrylate, and polyvinyl alcohol acetal.

[0094] In the carbon dioxide adsorption battery 10, the electrolyte layer 14 is a layer located between the negative electrode 12 and the separator 13. The thickness of the electrolyte layer 14 is not particularly limited, but is preferably 0.1 μm to 2 mm, and more preferably 1 μm to 1 mm. If the electrolyte layer 14 is too thin, not only will the amount of carbon dioxide fixed and the amount of electricity stored decrease, but tiny holes, i.e., pinholes, tend to form in the electrolyte layer 14. The formation of pinholes can lead to other problems, such as insufficient carbon dioxide adsorption or the flow of current that does not contribute to carbon dioxide adsorption. Furthermore, if the electrolyte layer 14 is too thick, the diffusion of carbon dioxide adsorbed in the electrolyte layer 14 within the electrolyte layer 14 slows, resulting in a discrepancy between the amount of carbon dioxide fixed and the amount of electricity stored, making it difficult to determine whether carbon dioxide has been sufficiently adsorbed during charging. This is believed to be due to the following reasons. In the carbon dioxide adsorption battery 10, the contribution of carbon dioxide diffusion in the electrolyte layer 14 and the diffusion of carbon dioxide-bound redox compounds to carbon dioxide adsorption is greater than the contribution of diffusion to charging. Furthermore, when the electrolyte layer 14 is thick, the influence of diffusion is greater than when it is thin. For these reasons, the difference in the rate of carbon dioxide adsorption between a thick and a thin electrolyte layer 14 is greater than the rate of carbon dioxide charge. Therefore, when the electrolyte layer 14 is thin, it is easy to determine whether carbon dioxide has been sufficiently adsorbed from the amount of stored electricity. However, when the electrolyte layer 14 is thick, as described above, a discrepancy occurs between the amount of fixed carbon dioxide and the amount of stored electricity, making it difficult to determine whether carbon dioxide has been sufficiently adsorbed from the amount of stored electricity. Therefore, it is believed that the thicker the electrolyte layer 14, the more difficult it is to determine whether carbon dioxide has been sufficiently adsorbed during charging. For the same reason, when the electrolyte layer 14 is too thick, it tends to be difficult to determine whether carbon dioxide has been sufficiently released during discharge.

[0095] The electrolyte layer 14 may include a substrate. Examples of the electrolyte layer 14 include a substrate impregnated with the electrolytic solution containing the compound. Examples of the substrate include glass fiber filter paper.

[0096] The method for manufacturing the electrolyte layer 14 is not particularly limited as long as the electrolyte layer 14 can be manufactured. When the electrolyte layer 14 includes the base material, for example, a method can be used in which the compound is dispersed or dissolved in the electrolyte solution, and the base material is impregnated with the electrolyte solution containing the redox compound. The impregnation is preferably performed while applying ultrasonic vibrations to the electrolyte solution and the base material. This can prevent the formation of minute holes, i.e., pinholes, in the electrolyte layer 14.

[0097] (Separator) The separator 13 is not particularly limited as long as it is a separator that suppresses permeation of the compound and is permeable to the electrolyte solution. That is, the separator 13 is less permeable to the compound than the electrolyte solution. Furthermore, the separator 13 is preferably permeable to the electrolyte solution but not to the compound. The separator 13 is permeable to the electrolyte solution but is provided to separate the electrolyte layer 14 from the porous electrode 11a so as to suppress permeation of the compound. Thus, the positive electrode 11 and the negative electrode 12 are separated by the separator 13. Examples of the separator 13 include separators commonly used in lithium secondary batteries, and particularly preferred are separators that have low resistance to ion migration of the electrolyte and excellent electrolyte humidification ability. Examples of materials for the separator include glass fiber, polyester, polyethylene, polypropylene, and polytetrafluoroethylene (PTFE). The separator material may be used alone or in combination of two or more. The separator 13 is made of the material of the separator 13 and may be in the form of a nonwoven fabric or a woven fabric. The pore size of the separator 13 is not particularly limited, but is preferably, for example, 0.01 to 10 μm. The thickness of the separator 13 is not particularly limited, but is preferably, for example, 5 to 300 μm.

[0098] (Flow path) The flow path 15 is not particularly limited as long as it is a flow path that can circulate a gas, and examples thereof include a flow path through which at least one of carbon dioxide adsorbed to the compound and carbon dioxide desorbed from the compound can flow. The flow path 15 is connected to the negative electrode 12 and can circulate gas that permeates the negative electrode 12 and gas that is released from the negative electrode 12. The flow path 15 may also be equipped with a valve 18 as necessary.

[0099] (Voltage Application Unit) As described above, the carbon dioxide adsorption battery 10 may be provided with the voltage application unit 16. By providing the carbon dioxide adsorption battery 10 with the voltage application unit 16, it is possible to make the carbon dioxide adsorption battery 10 into a carbon dioxide concentrator capable of concentrating carbon dioxide. That is, a carbon dioxide concentrator is obtained that includes the carbon dioxide adsorption battery 10 and the voltage application unit 16 that applies a voltage between the positive electrode 11 and the negative electrode 12.

[0100] The voltage application unit 16 is not particularly limited as long as it can apply a voltage between the positive electrode 11 and the negative electrode 12. Examples of the voltage application unit 16 include a secondary battery, an external power source, and a capacitor.

[0101] 2 , the carbon dioxide adsorption battery 10 is discharged after being charged by providing the resistor 17 between the positive electrode 11 and the negative electrode 12. The resistor 17 is not particularly limited as long as it can discharge the carbon dioxide adsorption battery 10.

[0102] There is no particular limitation on the manufacturing method of the carbon dioxide adsorption battery 10 as long as it can be manufactured with the above structure. Specific examples of the manufacturing method of the carbon dioxide adsorption battery 10 include a method of assembling the positive electrode 11, the negative electrode 12, the separator 13, the electrolyte layer 14, and the flow path 15, and further using the voltage application unit 16, the resistor 17, and the like, as necessary, by a general assembly method so as to have the structure shown in Figures 1 and 2 .

[0103] [Other Carbon Dioxide Adsorption Batteries] The carbon dioxide adsorption battery according to this embodiment is not limited to the carbon dioxide adsorption battery having the above configuration, as long as it includes the positive electrode, the negative electrode, the electrolyte layer, and the separator. For example, the carbon dioxide adsorption battery may include one positive electrode and two negative electrodes disposed on both sides of the positive electrode. Specifically, as shown in Figures 3 and 4, the carbon dioxide adsorption battery 20 includes the positive electrode 11, two negative electrodes 12 disposed on both sides of the positive electrode 11, two separators 13 disposed between the positive electrode 11 and each negative electrode 12, two electrolyte layers 14 disposed between each negative electrode 12 and each separator 13, and two flow paths 15 connected to each negative electrode 12. The positive electrode 11 may include the porous electrode 11a and may be composed of the porous electrode 11a. However, as shown in FIGS. 3 and 4 , when the porous electrode 11a and the current collector 11b are included, the porous electrode 11a is provided on both sides of the current collector 11b. With such a carbon dioxide adsorption battery 20, carbon dioxide is adsorbed to the compound contained in each of the electrolyte layers 14 that contacts each of the negative electrodes 12 during charging. That is, during charging, carbon dioxide-containing gas is circulated through the two flow paths 15 through which the carbon dioxide-containing gas flows, causing carbon dioxide to be adsorbed to the compound contained in each of the electrolyte layers 14, thereby charging. Then, as shown in FIG. 4 , carbon dioxide can be released from each of the negative electrodes 12 by discharging. As a result, the carbon dioxide adsorption battery 20 can adsorb and desorb carbon dioxide from either of the negative electrodes 12. As a result, the carbon dioxide adsorption battery can be charged while adsorbing carbon dioxide from a carbon dioxide-containing gas, and can desorb the carbon dioxide during discharge in a shorter time, even at a low voltage. 3 and 4 are schematic cross-sectional views showing another example of the configuration of a carbon dioxide adsorption battery according to an embodiment of the present invention (the carbon dioxide adsorption battery 20), with FIG. 3 showing the carbon dioxide adsorption battery 20 during charging and FIG. 2 showing the carbon dioxide adsorption battery 20 during discharging.

[0104] [Charging / Discharging Device] The charging / discharging device according to the embodiment of the present invention is a charging / discharging device including two or more of the carbon dioxide adsorption batteries. The charging / discharging device is not particularly limited as long as it includes two or more of the carbon dioxide adsorption batteries, and examples thereof include a charging / discharging device 30 as shown in FIG.

[0105] 5, the charging / discharging device 30 includes a first carbon dioxide adsorption battery 10a and a second carbon dioxide adsorption battery 10b. The first carbon dioxide adsorption battery 10a can be charged by connecting its negative electrode side 10a1 and positive electrode side 10a2 via the voltage application unit 16. That is, the charging / discharging device 30 can charge the first carbon dioxide adsorption battery 10a by connecting the positive electrode side 10a2 of the first carbon dioxide adsorption battery 10a and the voltage application unit 16 with a wiring 31, and connecting the voltage application unit 16 and the negative electrode side 10a1 of the first carbon dioxide adsorption battery 10a with a wiring 32. After charging the first carbon dioxide adsorption battery 10a, the negative electrode side 10a1 of the first carbon dioxide adsorption battery 10a and the negative electrode side 10b1 of the second carbon dioxide adsorption battery 10b are connected by a wiring 36, and the positive electrode side 10b2 of the second carbon dioxide adsorption battery 10b and the positive electrode side 10a2 of the first carbon dioxide adsorption battery 10a are connected by a wiring 35, thereby discharging the first carbon dioxide adsorption battery 10a and charging the second carbon dioxide adsorption battery 10b. After charging the second carbon dioxide adsorption battery 10b (after discharging the first carbon dioxide adsorption battery 10a), the negative electrode 10b1 of the second carbon dioxide adsorption battery 10b is connected to the negative electrode 10a1 of the first carbon dioxide adsorption battery 10a via a wiring 34, and the positive electrode 10a2 of the first carbon dioxide adsorption battery 10a is connected to the positive electrode 10b2 of the second carbon dioxide adsorption battery 10b via a wiring 33. This allows the second carbon dioxide adsorption battery 10b to be discharged while the first carbon dioxide adsorption battery 10a is charged. In this way, by once charging the first carbon dioxide adsorption battery 10a, the device can function as a charge / discharge device that can alternately charge and discharge the second carbon dioxide adsorption battery 10b and the first carbon dioxide adsorption battery 10a. Therefore, by including two or more carbon dioxide adsorption batteries, the charge / discharge device can alternately charge and discharge each of the carbon dioxide adsorption batteries. This makes the charge / discharge device highly energy efficient. The charging / discharging device can also separate carbon dioxide.In the first carbon dioxide adsorption battery 10a and the second carbon dioxide adsorption battery 10b, carbon dioxide is adsorbed from a gas containing carbon dioxide (such as air containing nitrogen and carbon dioxide) during charging, and the adsorbed carbon dioxide is released during discharging. Fig. 5 is a schematic diagram showing an example of the configuration of a charge / discharge device according to an embodiment of the present invention.

[0106] As described above, this specification discloses various aspects of the technology, the main technologies of which are summarized below.

[0107] A carbon dioxide adsorption battery according to a first aspect of the present invention is a carbon dioxide adsorption battery comprising: a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, an electrolyte layer disposed between the negative electrode and the separator, and a flow path connected to the negative electrode, wherein the electrolyte layer contains an electrolyte solution capable of dissolving carbon dioxide and a compound capable of adsorbing and desorbing carbon dioxide by an electrochemical reaction, the negative electrode is a gas-permeable electrode, and the positive electrode comprises a porous electrode containing the electrolyte solution.

[0108] With this configuration, it is possible to provide a carbon dioxide adsorption battery that can adsorb carbon dioxide from a gas containing carbon dioxide while charging and desorb the carbon dioxide during discharge in a short time even at a low voltage. This is believed to be due to the following reasons.

[0109] The negative electrode allows gas present around the negative electrode to pass through. When gas passes through the negative electrode, the gas that has passed through the negative electrode comes into contact with the negative electrode side of the electrolyte layer. Therefore, when carbon dioxide is contained in the gas present around the negative electrode, the carbon dioxide contained in the gas present around the negative electrode comes into contact with the electrolyte layer. Therefore, since the electrolyte layer contains an electrolyte solution capable of dissolving carbon dioxide, the carbon dioxide contained in the gas present around the negative electrode is dissolved in the electrolyte solution contained in the electrolyte layer.

[0110] In the carbon dioxide adsorption battery, when a voltage is applied between the positive electrode and the negative electrode such that the compound contained in the electrolyte layer is capable of adsorbing carbon dioxide through an electrochemical reaction, carbon dioxide dissolved in the electrolytic solution contained in the electrolyte layer is adsorbed by the compound. Furthermore, a separator provided in the carbon dioxide adsorption battery suppresses permeation of the compound, so that the compound with adsorbed carbon dioxide is less likely to permeate the separator and migrate to the positive electrode side.

[0111] Therefore, when carbon dioxide is adsorbed to the compound, the carbon dioxide adsorption battery enters a charged state. Furthermore, because carbon dioxide dissolved in the electrolyte is adsorbed to the compound, dissolution of carbon dioxide into the electrolyte is promoted, and the carbon dioxide adsorption battery preferably progresses to a charged state. For these reasons, as shown in FIG. 1 , in the carbon dioxide adsorption battery, when a gas containing carbon dioxide is circulated through a flow path connected to the negative electrode and a voltage is applied between the positive electrode and the negative electrode such that the compound can adsorb carbon dioxide through an electrochemical reaction, carbon dioxide is adsorbed and the battery can be charged. Furthermore, as described above, in the carbon dioxide adsorption battery, since the compound is unlikely to permeate through the separator, even if the application of voltage between the positive electrode and the negative electrode is stopped, the state in which carbon dioxide is adsorbed to the compound, i.e., the charged state, is preferably maintained as long as the positive electrode and the negative electrode are not electrically connected and discharged.

[0112] 2, when the positive electrode and the negative electrode are electrically connected and discharged, the compound is no longer in a state in which it can adsorb carbon dioxide through an electrochemical reaction, and the carbon dioxide adsorbed to the compound is desorbed from the compound. Thus, in the carbon dioxide adsorption battery, carbon dioxide is released from the negative electrode into the flow path connected to the negative electrode during discharge. The gas released from the carbon dioxide adsorption battery during discharge is the gas that was adsorbed to the compound in the carbon dioxide adsorption battery during charge, and therefore has a very high carbon dioxide concentration.

[0113] For these reasons, the carbon dioxide adsorption battery selectively adsorbs carbon dioxide from a gas containing carbon dioxide during charging, and releases the adsorbed carbon dioxide during discharging, thereby concentrating carbon dioxide.

[0114] Furthermore, in the carbon dioxide adsorption battery, charge compensation without the electrochemical reaction (specifically, charge compensation like that of a capacitor) is also performed in the positive electrode by applying the voltage between the positive electrode and the negative electrode. In this case, since the positive electrode of the carbon dioxide adsorption battery includes a porous electrode, the surface area of ​​the positive electrode is large, and this charge compensation can be performed suitably. This charge compensation has lower resistance than when the electrochemical reaction is involved, and therefore can contribute to operation at a lower voltage (i.e., lower power consumption) compared to conventional technologies.

[0115] As described above, the carbon dioxide adsorption battery can be charged while adsorbing carbon dioxide from a gas containing carbon dioxide, and can desorb the carbon dioxide during discharge in a short time even at a low voltage.

[0116] A carbon dioxide adsorption battery according to a second aspect of the present invention is the carbon dioxide adsorption battery according to the first aspect of the present invention, wherein the carbon dioxide adsorption battery contains a redox compound, and the capacity derived from the redox compound on the positive electrode side of the separator is smaller than the capacity derived from the redox compound on the negative electrode side of the separator.

[0117] In the carbon dioxide adsorption battery, since charging and discharging are possible even if the above-described adsorption and desorption of carbon dioxide does not occur on the positive electrode side, the redox compound may be contained on the positive electrode side of the separator, but it is not necessary to contain the redox compound. Therefore, according to the above configuration, even if the redox compound is contained on the positive electrode side of the separator, the battery can be charged while adsorbing carbon dioxide from a carbon dioxide-containing gas and desorb the carbon dioxide during discharge, regardless of whether the redox compound is contained on the positive electrode side of the separator or not, so that the capacity derived from the redox compound present on the positive electrode side of the separator is less than the capacity derived from the redox compound present on the negative electrode side of the separator.

[0118] A carbon dioxide adsorption battery according to a third aspect of the present invention is the carbon dioxide adsorption battery according to the second aspect of the present invention, wherein the redox compound is not contained on the positive electrode side of the separator.

[0119] In the carbon dioxide adsorption battery, charging and discharging are possible even if the above-described carbon dioxide adsorption and desorption does not occur on the positive electrode side, and therefore the positive electrode side of the separator (for example, a porous electrode provided on the positive electrode) does not necessarily contain a compound capable of adsorbing and desorbing carbon dioxide by an electrochemical reaction. Furthermore, the positive electrode side of the separator is not limited to a compound capable of adsorbing and desorbing carbon dioxide by an electrochemical reaction, and does not necessarily contain the redox compound as in the above configuration. Therefore, with the above configuration, even if the redox compound is not contained on the positive electrode side of the separator, it is possible to charge the battery while adsorbing carbon dioxide from a carbon dioxide-containing gas and desorb the carbon dioxide during discharge.

[0120] A carbon dioxide adsorption battery according to a fourth aspect of the present invention is a carbon dioxide adsorption battery according to any one of the first to third aspects of the present invention, wherein the flow path is a flow path through which at least one of carbon dioxide adsorbed by the compound contained in the electrolyte layer and carbon dioxide desorbed from the compound contained in the electrolyte layer can flow.

[0121] According to this configuration, in the carbon dioxide adsorption battery, carbon dioxide adsorbed by the compound contained in the electrolyte layer can be made to flow through the flow path during charging. Also, carbon dioxide desorbed from the compound contained in the electrolyte layer can be made to flow through the flow path during discharging. As a result, the carbon dioxide adsorption battery can more reliably perform the above-described process of charging while adsorbing carbon dioxide from a carbon dioxide-containing gas and desorbing the carbon dioxide during discharging in a short time even at a low voltage.

[0122] A carbon dioxide adsorption battery according to a fifth aspect of the present invention is the carbon dioxide adsorption battery according to any one of the first to fourth aspects of the present invention, in which when a voltage is applied between the positive electrode and the negative electrode, the battery is charged and carbon dioxide is adsorbed by the compound contained in the electrolyte layer, and when the positive electrode and the negative electrode are electrically connected and the battery is discharged, the carbon dioxide adsorbed by the compound contained in the electrolyte layer is desorbed.

[0123] With this configuration, as described above, charging can be performed while adsorbing carbon dioxide from a gas containing carbon dioxide, and desorbing the carbon dioxide during discharge can be performed in a short time even at a low voltage.

[0124] A carbon dioxide adsorption battery according to a sixth aspect of the present invention is the carbon dioxide adsorption battery according to any one of the first to fifth aspects of the present invention, wherein the compound contained in the electrolyte layer is a compound that adsorbs carbon dioxide by being electrolytically reduced and desorbs carbon dioxide by being electrolytically oxidized.

[0125] With this configuration, the battery can be charged while adsorbing carbon dioxide from a gas containing carbon dioxide, and can desorb the carbon dioxide during discharge, even at a low voltage, in a short time. This is believed to be due to the following reasons.

[0126] In the carbon dioxide adsorption battery, during charging, the compound contained in the electrolyte layer is electrolytically reduced to a reduced form in the electrolyte layer. Specifically, in the carbon dioxide adsorption battery, a voltage is applied between the positive electrode and the negative electrode such that the potential of the negative electrode is lower than the potential of the positive electrode, as a voltage at which the compound contained in the electrolyte layer is capable of adsorbing carbon dioxide through an electrochemical reaction. Since the electrolyte layer is close to the negative electrode with a lower potential, the compound contained in the electrolyte layer is electrolytically reduced to a reduced form. Carbon dioxide dissolved in the electrolyte solution contained in the electrolyte layer combines with the reduced form and is captured in the electrolyte layer. Subsequently, upon discharge, the reduced form of the compound is electrolytically oxidized, returning to its state before electrolytic reduction, and carbon dioxide is desorbed from the compound. As a result, carbon dioxide is released from the negative electrode. In this way, the compound can suitably adsorb and desorb carbon dioxide to the compound. Therefore, charging while adsorbing carbon dioxide from a carbon dioxide-containing gas and desorbing the carbon dioxide during discharge can be performed in a short time, even at a low voltage.

[0127] A carbon dioxide adsorption battery according to a seventh aspect of the present invention is the carbon dioxide adsorption battery according to any one of the first to sixth aspects of the present invention, wherein the compound contained in the electrolyte layer is a compound having an N-oxy radical group in the molecule.

[0128] With this configuration, the battery can be charged while adsorbing carbon dioxide from a gas containing carbon dioxide, and can desorb the carbon dioxide during discharge in a short time even at a low voltage. This is believed to be due to the following reasons.

[0129] This is thought to be because, if the compound contained in the electrolyte layer is a compound having the N-oxy radical group in its molecule, carbon dioxide is more easily adsorbed by electrolytic reduction and more easily desorbed by electrolytic oxidation. More specifically, in the carbon dioxide adsorption battery, during charging, the compound accepts electrons, thereby reducing the N-oxy radical group contained in the compound to form an N-oxy anion group. Carbon dioxide dissolved in the electrolyte solution contained in the electrolyte layer is more likely to bond to this N-oxy anion group, making it more easily incorporated into the electrolyte layer. Furthermore, during discharging, the N-oxy anion group is more likely to be electrolytically oxidized by supplying electrons to the outside, making it more likely to become an N-oxy radical group or an N-oxy cation group, thereby facilitating desorption of carbon dioxide from the compound. In this way, the compound can more effectively adsorb and desorb carbon dioxide. Therefore, the carbon dioxide adsorption battery can be charged while adsorbing carbon dioxide from a carbon dioxide-containing gas, and can desorb the carbon dioxide during discharging in a short time, even at a low voltage.

[0130] A carbon dioxide adsorption battery according to an eighth aspect of the present invention is the carbon dioxide adsorption battery according to the seventh aspect of the present invention, wherein the compound is a compound in which two quaternary carbons are bonded to the N-oxy radical group.

[0131] With this configuration, it is possible to adsorb more carbon dioxide from a gas containing carbon dioxide, and to maintain a charged state for a longer period. Therefore, the carbon dioxide adsorption battery can adsorb more carbon dioxide from a gas containing carbon dioxide, charge while this adsorption occurs, and desorb the carbon dioxide during discharge in a short time, even at a low voltage. This is thought to be due to the following.

[0132] It is believed that the decomposition of the N-oxy radical group, which would otherwise occur if a hydrogen radical were abstracted from the carbon adjacent to the N-oxy radical group, can be suppressed, and therefore it is believed that the compound can more suitably adsorb and desorb carbon dioxide.

[0133] A carbon dioxide adsorption battery according to a ninth aspect of the present invention is the carbon dioxide adsorption battery according to any one of the first to eighth aspects of the present invention, wherein the compound contained in the electrolyte layer is any one of a compound represented by the following formula (1), a compound represented by the following formula (2), and a compound represented by the following formula (3), or a compound having in its molecule a group in which one hydrogen atom has been eliminated from a compound represented by any one of the following formulas (1) to (3):

[0134]

[0135]

[0136]

[0137] In formulas (1) to (3), Z is -CR ５ R ６ CR ７ R ８ -, -CR ９ R １０ CR １１ R １２ CR １３ R １４ -, - (CR １５ R １６ ) O-, -(CR １７ R １８ ) NR ２７ -, - (CR １９ R ２０ ) O (CR ２１ R ２２ ) - or - (CR ２３ R ２４ ) NR ２８ (CR ２５ R ２６ )-, R １ ~R ４ each independently represents a substituent, R １ and R２ may be bonded to each other to form a ring, and R ３ and R ４ may be bonded to each other to form a ring, and R ５ ~R ２８ each independently represents a hydrogen atom or a substituent.

[0138] With this configuration, the carbon dioxide adsorption battery can adsorb more carbon dioxide from a gas containing carbon dioxide and maintain a charged state for a longer period of time. Therefore, the carbon dioxide adsorption battery can adsorb more carbon dioxide from a gas containing carbon dioxide, charge while adsorbing carbon dioxide, and desorb carbon dioxide during discharge in a short period of time, even at a low voltage. This is thought to be because the compound can inhibit the decomposition of the N-oxy radical group, which would otherwise occur if a hydrogen radical were to be extracted from the carbon adjacent to the N-oxy radical group.

[0139] A carbon dioxide adsorption battery according to a tenth aspect of the present invention is the carbon dioxide adsorption battery according to any one of the first to ninth aspects of the present invention, wherein the negative electrode is made of a conductive material including at least one material selected from the group consisting of metal fibers, conductive fibers, metal particles, conductive ceramics, graphite, carbon nanotubes, activated carbon, and carbon fibers.

[0140] With this configuration, the carbon dioxide adsorption battery can adsorb more carbon dioxide from a gas containing carbon dioxide and maintain a charged state for a longer period of time. That is, the carbon dioxide adsorption battery can adsorb more carbon dioxide from a gas containing carbon dioxide, charge while adsorbing, and desorb the carbon dioxide during discharge in a short period of time even at a low voltage. This is thought to be because the negative electrode not only allows a voltage to be more suitably applied between the negative electrode and the positive electrode, but also allows carbon dioxide to more suitably permeate.

[0141] A carbon dioxide adsorption battery according to an eleventh aspect of the present invention is the carbon dioxide adsorption battery according to any one of the first to tenth aspects of the present invention, wherein the porous electrode is made of a porous material containing at least one selected from the group consisting of conductive ceramics, graphite, carbon nanotubes, activated carbon, and carbon fibers.

[0142] This configuration allows the battery to be charged while adsorbing carbon dioxide from a carbon dioxide-containing gas and to desorb the carbon dioxide during discharge in a short time, and further allows the battery to be driven at a lower voltage (i.e., lower power consumption). This is thought to be due to the fact that charge compensation without electrochemical reaction can be more suitably performed at the positive electrode.

[0143] A carbon dioxide adsorption battery according to a twelfth aspect of the present invention is the carbon dioxide adsorption battery according to any one of the first to eleventh aspects of the present invention, wherein the specific surface area of ​​the porous electrode is 100 m ２ / g or more.

[0144] This configuration allows the battery to be charged while adsorbing carbon dioxide from a carbon dioxide-containing gas and to desorb the carbon dioxide during discharge in a short time, and further allows the battery to be driven at a lower voltage (i.e., lower power consumption). This is thought to be due to the fact that charge compensation without electrochemical reaction can be more suitably performed at the positive electrode.

[0145] A charge / discharge device according to a thirteenth aspect of the present invention is a charge / discharge device including two or more carbon dioxide adsorption batteries according to any one of the first to twelfth aspects of the present invention.

[0146] This configuration makes it possible to provide a charging / discharging device including the carbon dioxide adsorption battery. Furthermore, by including two or more carbon dioxide adsorption batteries, the charging / discharging device can alternately charge and discharge each of the carbon dioxide adsorption batteries. Specifically, first, one of the carbon dioxide adsorption batteries (first battery) is charged. Then, the other carbon dioxide adsorption battery (second battery) connected to the first battery can be charged by discharging the first battery. Then, the first battery can be charged by discharging the second battery. Thus, by once charging the first battery, the charging / discharging device can be used as a charging / discharging device that can alternately charge and discharge the first battery and the second battery. This makes the charging / discharging device highly energy-efficient. Furthermore, the charging / discharging device can alternately adsorb and desorb carbon dioxide from the first battery and the second battery, and can separate carbon dioxide from a carbon dioxide-containing gas in a short time, even at a low voltage.

[0147] According to the present invention, it is possible to provide a carbon dioxide adsorption battery that can be charged while adsorbing carbon dioxide from a gas containing carbon dioxide, and desorb the carbon dioxide during discharge in a short time even at a low voltage. Furthermore, according to the present invention, it is possible to provide a charge / discharge device that includes the carbon dioxide adsorption battery.

[0148] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0149] Example 1 <Fabrication of Carbon Dioxide Adsorption Battery> A carbon dioxide adsorption battery having the structure shown in FIGS. 1 and 2 was fabricated by the following procedure.

[0150] (Electrolyte Layer) 6.5 g of poly(vinylidene fluoride-co-hexafluoropropylene) (Sigma-Aldrich) was added to 100.0 g of dimethylformamide (Fujifilm Wako Pure Chemical Industries, Ltd.), and dissolved by stirring at 80° C. for 3 hours. Next, 24.0 g of a compound [poly(4-methacryloyloxy-2,2,6,6-tetramethylpiperidinyloxy radical)] (non-volatile) obtained by polymerizing the compound, 4-methacryloyloxy-2,2,6,6-tetramethylpiperidinyloxy radical (Tokyo Chemical Industry Co., Ltd.) as a monomer by a conventional anionic polymerization method, was added to the resulting solution, and the solution was dissolved by stirring at 80° C. for 3 hours. Next, 12.9 g of an ionic liquid [1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (non-volatile) (emimFSI manufactured by Sigma-Aldrich)], which is an electrolyte capable of dissolving carbon dioxide, was added to the obtained solution, heated to 40 ° C, and stirred and mixed for 3 hours. Using the liquid obtained in this way, a liquid film with a thickness of 500 μm was formed on a glass plate with an applicator and dried under reduced pressure at 60 ° C for 8 hours. The dried film obtained by the drying was peeled off from the glass plate. In this way, a dried film with a thickness of 100 μm was obtained. This obtained dried film was cut into a size of 20 mm length x 24 mm width and used as an electrolyte layer. When the obtained electrolyte layer was visually inspected, no small holes (pinholes) were observed.

[0151] (Positive electrode) Activated carbon (YP-50F manufactured by Kuraray Co., Ltd.), styrene-butadiene rubber (SBR) (TRD2001 manufactured by JSR Corporation), carboxymethyl cellulose (CMC) (Cellogen F-BSH manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and acetylene black (Denka Black manufactured by Denka Co., Ltd.) were mixed with water to give a ratio of activated carbon: SBR: CMC: acetylene black = 90: 3: 2: 5 (mass ratio), to obtain a slurry. The obtained slurry was applied to a 20 μm thick etched aluminum foil (manufactured by Hosen Co., Ltd.) using a bar coater, and then dried for 7 hours at 120 ° C. under a reduced pressure atmosphere using a glass tube oven to obtain a polarizable electrode (an electrode in which a porous electrode and a current collector are integrated). That is, the layer formed on the etched aluminum foil (current collector) was a porous electrode. The BET specific surface area of ​​this porous electrode was calculated from the obtained adsorption isotherm by performing nitrogen adsorption isotherm measurement, and was found to be 1500 m ２ The electrochemical conductivity of the resulting electrode (positive electrode) was 100 μm. The resulting electrode was cut into a size of 30 mm length x 30 mm width, and the ionic liquid was added thereto. A conductive copper foil tape (used as a tab) was attached to one side of an etched aluminum foil to form a positive electrode.

[0152] (Negative electrode) Carbon paper (GDL35BC manufactured by SGL Carbon Japan Co., Ltd.) was cut into several pieces each measuring 30 mm long x 30 mm wide. The BET specific surface area of ​​this negative electrode was calculated from the nitrogen adsorption isotherm obtained by measuring the nitrogen adsorption isotherm, and found to be 4 m ２ / g.

[0153] The negative electrode was prepared by attaching a conductive copper foil tape (used as a tab) to one side of the cut-out carbon paper.

[0154] (Separator) A polypropylene separator (Celgard #2400 manufactured by Polypore Corporation) cut into a size of 30 mm length x 30 mm width was used as the separator.

[0155] (Flow path) A polytetrafluoroethylene resin plate was cut into a size of 50 mm length × 50 mm width × 5 mm thickness, and two holes were drilled at appropriate locations. A groove with a depth of 1 mm × length of 20 mm × width of 20 mm was dug in this cut-out resin plate to connect to the holes. This was used as a flow path.

[0156] (Carbon dioxide adsorption battery) The negative electrode, the electrolyte layer, the separator immersed in the ionic liquid, and the positive electrode immersed in the ionic liquid were laminated in this order, and the flow path was assembled on the negative electrode surface to produce a carbon dioxide adsorption battery having a structure as shown in Figures 1 and 2. During charging of the carbon dioxide adsorption battery, a power supply serving as a voltage application unit was connected to the conductive copper foil tape of the positive electrode and the conductive copper foil tape of the negative electrode, as shown in Figure 1. During discharging of the carbon dioxide adsorption battery, a resistor was connected to the conductive copper foil tape of the positive electrode and the conductive copper foil tape of the negative electrode, as shown in Figure 2.

[0157] In the carbon dioxide adsorption battery of Example 1, an electrolyte is present on the positive electrode side of the separator, but no redox compound is present, or even if present, only a small amount of redox compound leaks from the electrolyte layer through the separator. This shows that the capacity derived from the redox compound on the positive electrode side of the separator is smaller than the capacity derived from the redox compound on the negative electrode side of the separator.

[0158] Example 2 The same procedure as in Example 1 was carried out, except that the amount of poly(4-methacryloyloxy-2,2,6,6-tetramethylpiperidinyloxy radical) added was changed from 24.0 g to 48.0 g.

[0159] Example 3 The same procedure as in Example 1 was carried out, except that the polarizable electrode used as the positive electrode in Example 1 was used as the negative electrode instead of the carbon paper.

[0160] Example 4 The same procedure as in Example 1 was carried out, except that the electrolyte layer was added between the separator and the positive electrode immersed in the ionic liquid.

[0161] Example 5 The same procedure as in Example 4 was carried out, except that the thickness of the electrolyte layer was set to 50 μm.

[0162] Example 6 The same procedure as in Example 4 was carried out, except that the activated carbon used in the porous electrode was changed to YP-80F manufactured by Kuraray Co., Ltd. The BET specific surface area of ​​this porous electrode was 2100 m ２ / g.

[0163] [Example 7] The same procedure as in Example 4 was carried out, except that the activated carbon used in the porous electrode was changed to Kuraray Coal GW60 / 150D manufactured by Kuraray Co., Ltd. The BET specific surface area of ​​this porous electrode was 900 m ２ / g.

[0164] Comparative Example 1 The same procedure as in Example 1 was carried out, except that the ionic liquid [1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (non-volatile)] was not added to the positive electrode.

[0165] Comparative Example 2 The same procedure as in Example 1 was carried out, except that the same positive electrode as the negative electrode prepared in Example 1 was used.

[0166] Comparative Example 3 The same procedure as in Example 4 was carried out, except that the same positive electrode as the negative electrode prepared in Example 1 was used.

[0167] Table 1 shows the specific surface area of ​​the porous electrode, whether or not an ionic liquid was added to the porous electrode, the amount of redox compound added to the electrolyte layer on the positive electrode side, the type of negative electrode, and the amount of redox compound added to the electrolyte layer on the negative electrode side in Examples 1 to 7 and Comparative Examples 1 to 3. When no electrolyte layer was present, the "redox compound added amount" column is marked with "-". Furthermore, when the total pore volume was 0.1 cm3 or less, the porous electrode was used. ３ / g or less, the average pore diameter can be considered to be 50 nm or more for the reasons described above, and is therefore indicated as "50 or more" here.

[0168]

[0169] [Evaluation] The carbon dioxide adsorption battery was evaluated by the following evaluation method.

[0170] (Test 1) First, the carbon dioxide adsorption battery was placed in an environment at room temperature (28°C), and a 2-liter gas bag filled with a mixed gas of carbon dioxide and nitrogen was attached to the holes in the flow path. A portable carbon dioxide concentration meter (CGP-31 manufactured by DKK-TOA Corporation) was attached to each of the holes in the flow path. The carbon dioxide concentration measured at the time of attachment was 0.4% (4000 ppm). Then, by adjusting the power supply, 1.5 V was applied between the positive electrode and the negative electrode, charging was performed until the current value reached 0.01 mA, and then discharging to 0 V, thereby measuring the discharge characteristics of the carbon dioxide adsorption battery. Specifically, the discharge characteristics of the carbon dioxide adsorption battery were measured (discharge rate characteristic evaluation) as follows.

[0171] (Evaluation of Discharge Capacity Characteristics) Using a charge / discharge tester (TOSCAT manufactured by Toyo Systems Co., Ltd.), the carbon dioxide adsorption battery was charged at a constant current of 2.5 mA until the voltage reached 1.5 V, and then continuously charged at a constant voltage of 1.5 V until the voltage reached 0.01 mA. Thereafter, the battery was discharged at a constant current of 2.5 mA down to 0 V, and the discharge capacity (F / g) at this time was measured. The discharge capacity was calculated as the capacity per weight of the radical material to facilitate comparison of the efficiency of the radical materials.

[0172] When this discharge rate characteristic evaluation was measured, after the end of the charging, the residual carbon dioxide concentration (CO after charging) was measured using a portable carbon dioxide concentration meter (CGP-31 manufactured by DKK-TOA Corporation) attached to the hole of the flow path on the first electrode side. ２ After the discharge, the carbon dioxide concentration (CO concentration after discharge) was measured using a portable carbon dioxide concentration meter attached to the hole of the flow path on the first electrode side. ２ The concentration was measured.

[0173] The results are shown in Table 2.

[0174] (Test 2) The carbon dioxide adsorption battery was driven by charging at a constant current of 10 mA until the voltage reached 1.5 V, and then by charging at a constant voltage of 1.5 V, and the change over time was observed. The results are shown in Table 3.

[0175]

[0176]

[0177] As can be seen from Table 2, the carbon dioxide adsorption batteries (Examples 1 to 3) each having a positive electrode with a porous electrode containing an electrolyte solution, a gas-permeable negative electrode, the separator, an electrolyte solution capable of dissolving carbon dioxide, and an electrolyte layer containing a compound capable of adsorbing and desorbing carbon dioxide through an electrochemical reaction were capable of being charged and discharged even at a relatively low voltage of 1.5 V. Unlike the carbon dioxide adsorption batteries not having such a configuration (Comparative Example 1), the carbon dioxide adsorption batteries according to Examples 1 to 3 were found to be able to adsorb carbon dioxide even when charged at a relatively low voltage and to release the adsorbed carbon dioxide during discharge.

[0178] As can be seen from Table 3, the carbon dioxide adsorption batteries (Example 1 and Examples 4 to 7) each comprising a positive electrode with a porous electrode containing an electrolytic solution, a gas-permeable negative electrode, the separator, an electrolytic solution capable of dissolving carbon dioxide, and an electrolyte layer containing a compound capable of adsorbing and desorbing carbon dioxide by an electrochemical reaction, adsorbed a large amount of carbon dioxide in a short time of within 30 minutes from the start of operation, even at a relatively low voltage of 1.5 V, compared with the carbon dioxide adsorption batteries (Comparative Examples 2 and 3) that did not use a positive electrode with a porous electrode.

[0179] From the above, it has been found that a carbon dioxide adsorption battery comprising a positive electrode with a porous electrode containing an electrolyte solution, a gas-permeable negative electrode, the separator, an electrolyte solution capable of dissolving carbon dioxide, and an electrolyte layer containing a compound capable of adsorbing and desorbing carbon dioxide by an electrochemical reaction can be charged while adsorbing carbon dioxide from a carbon dioxide-containing gas, and can desorb the carbon dioxide during discharge in a short time even at a low voltage.

[0180] This application is based on Japanese Patent Application No. 2024-069619 filed on April 23, 2024, the contents of which are incorporated herein by reference.

[0181] In order to express the present invention, the present invention has been properly and sufficiently described through the embodiments in the above, but it should be recognized that those skilled in the art can easily change and / or improve the above-mentioned embodiments. Therefore, unless the changes or improvements made by those skilled in the art are at a level that causes departure from the scope of the claims described in the claims, such changes or improvements are interpreted as being included in the scope of the claims.

[0182] According to the present invention, there is provided a carbon dioxide adsorption battery that can adsorb carbon dioxide from a carbon dioxide-containing gas while charging and desorb the carbon dioxide during discharge in a short time even at a low voltage. Also, according to the present invention, there is provided a charge / discharge device that includes the carbon dioxide adsorption battery.

Claims

1. A carbon dioxide adsorption battery comprising: a positive electrode; a negative electrode; a separator disposed between the positive electrode and the negative electrode; an electrolyte layer disposed between the negative electrode and the separator; and a flow path connected to the negative electrode, wherein the electrolyte layer contains an electrolyte solution capable of dissolving carbon dioxide and a compound capable of adsorbing and desorbing carbon dioxide through an electrochemical reaction, the negative electrode is a gas-permeable electrode, and the positive electrode comprises a porous electrode containing the electrolyte solution.

2. The carbon dioxide adsorption battery according to claim 1, wherein the carbon dioxide adsorption battery contains a redox compound, and the capacity derived from the redox compound on the positive electrode side of the separator is smaller than the capacity derived from the redox compound on the negative electrode side of the separator.

3. The carbon dioxide adsorption battery according to claim 2, wherein the redox compound is not contained on the positive electrode side of the separator.

4. A carbon dioxide adsorption battery according to any one of claims 1 to 3, wherein the flow path is a flow path through which at least one of carbon dioxide adsorbed by the compound contained in the electrolyte layer and carbon dioxide desorbed from the compound contained in the electrolyte layer can flow.

5. The carbon dioxide adsorption battery according to any one of claims 1 to 4, wherein when a voltage is applied between the positive electrode and the negative electrode, charging occurs and carbon dioxide is adsorbed by the compound contained in the electrolyte layer; and when the positive electrode and the negative electrode are electrically connected and discharging occurs, the carbon dioxide adsorbed by the compound contained in the electrolyte layer is desorbed.

6. The carbon dioxide adsorption battery according to any one of claims 1 to 5, wherein the compound contained in the electrolyte layer is a compound that adsorbs carbon dioxide by undergoing electrolytic reduction and desorbs carbon dioxide by undergoing electrolytic oxidation.

7. The carbon dioxide adsorption battery according to any one of claims 1 to 6, wherein the compound contained in the electrolyte layer is a compound having an N-oxy radical group in the molecule.

8. The carbon dioxide adsorption battery according to claim 7, wherein the compound is a compound in which two quaternary carbons are bonded to the N-oxy radical group.

9. The carbon dioxide adsorption battery according to any one of claims 1 to 8, wherein the compound contained in the electrolyte layer is any one of a compound represented by the following formula (1), a compound represented by the following formula (2), and a compound represented by the following formula (3), or a compound having in its molecule a group in which one hydrogen atom has been eliminated from a compound represented by any one of the following formulas (1) to (3): [In formulas (1) to (3), Z is —CR ５ R ６ CR ７ R ８ -, -CR ９ R １０ CR １１ R １２ CR １３ R １４ -, - (CR １５ R １６ ) O-, -(CR １７ R １８ ) NR ２７ -, - (CR １９ R ２０ ) O (CR ２１ R ２２ ) - or - (CR ２３ R ２４ ) NR ２８ (CR ２５ R ２６ )-, R １ ~R ４ each independently represents a substituent, R １ and R ２ may be bonded to each other to form a ring, and R ３ and R ４ may be bonded to each other to form a ring, and R ５ ~R ２８ each independently represents a hydrogen atom or a substituent.

10. The carbon dioxide adsorption battery according to any one of claims 1 to 9, wherein the negative electrode is made of a conductive material containing at least one material selected from the group consisting of metal fibers, conductive fibers, metal particles, conductive ceramics, graphite, carbon nanotubes, activated carbon, and carbon fibers.

11. The carbon dioxide adsorption battery according to any one of claims 1 to 10, wherein the porous electrode is made of a porous material containing at least one material selected from the group consisting of conductive ceramics, graphite, carbon nanotubes, activated carbon, and carbon fibers.

12. The specific surface area of ​​the porous electrode is 100 m ２ The carbon dioxide adsorption battery according to any one of claims 1 to 11, wherein the carbon dioxide adsorption battery has a capacitance of 1 / g or more.

13. A charging / discharging device comprising two or more carbon dioxide adsorption batteries according to any one of claims 1 to 12.

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