Carbon dioxide adsorption battery and charging / discharging device

Abstract

One embodiment 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 comprises an electrolyte capable of dissolving carbon dioxide and a compound capable of adsorbing and desorbing carbon dioxide through an electrochemical reaction; the negative electrode is an electrode through which gas can pass; and the positive electrode comprises a porous electrode containing an electrolyte.

Description

[Technical Field]

[0001] This invention relates to a carbon dioxide adsorption battery and a charging and discharging device. [Previous Technology]

[0002] Carbon dioxide is not only a substance that makes up about 0.04% of the atmosphere and is widely present on Earth, but it is also widely used in industry. Examples of its uses include: foaming gases for carbonated beverages, bath products, and fire extinguishers; dry ice for cooling; and emergency replenishment air for bicycle tires. Furthermore, carbon dioxide can be used as an extraction solvent for caffeine extraction by becoming supercritical. It is also used in industrial processing lasers and in medical laser scalpels. Additionally, carbon dioxide is sometimes used as a refrigerant in compressors, replacing chlorofluorocarbon (CFC) refrigerants. In agriculture, carbon dioxide is used, for example, to accelerate strawberry cultivation and as a fertilizer for aquatic plants in ornamental water tanks. It is also used in the CA (Controlled Atmosphere) storage of fresh agricultural products.

[0003] As mentioned above, carbon dioxide is used in various fields, therefore, methods are needed to obtain carbon dioxide by separating it from gases containing carbon dioxide, such as air. Furthermore, carbon dioxide is also considered a contributing factor to global warming. From this perspective, it is also necessary to separate carbon dioxide from gases containing carbon dioxide and utilize it. To utilize carbon dioxide, it is necessary to develop, for example, methods for separating carbon dioxide from gases containing carbon dioxide, devices for adsorbing and separating carbon dioxide, and devices for utilizing carbon dioxide.

[0004] Various methods have been proposed for separating carbon dioxide from a mixture of oxygen and carbon dioxide, such as air. Examples of such separation methods include: using a carbon dioxide adsorbent to adsorb carbon dioxide from the air, followed by releasing the adsorbed carbon dioxide from the adsorbent, thereby separating the carbon dioxide from the air. Examples of adsorbents for adsorbing carbon dioxide include: activated carbon, amine solvents, and aqueous solutions of potassium carbonate. Furthermore, more specifically, methods for separating carbon dioxide using adsorbents include: pressure-swing adsorption (PSA), where carbon dioxide is adsorbed onto an adsorbent under high pressure and then released from the adsorbent under reduced pressure. Examples of adsorbents used in separating carbon dioxide using this PSA method include the adsorbent described in Patent Document 1.

[0005] Patent Document 1 discloses a carbon dioxide adsorbent, which is composed of a composition formed by ion exchange of 2-80 equivalents of sodium ions from a sodium-containing aluminum silicate with barium ions. According to Patent Document 1, its main purpose is to provide an adsorbent with a high selectivity for carbon dioxide and a large absorption capacity even under conditions of high moisture content. Furthermore, Patent Document 1 discloses that this adsorbent can be appropriately used for the separation and concentration of carbon dioxide by the PSA method.

[0006] Examples of devices for adsorbing and separating carbon dioxide include, for example, the acidic gas adsorption and desorption element described in Patent Document 2 and the carbon dioxide separation device described in Patent Document 3.

[0007] Patent document 2 discloses an acidic gas adsorption and desorption element, which includes: an acidic gas adsorption and desorption layer containing 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 holding the acidic gas adsorption and desorption layer.

[0008] Patent Document 3 discloses a carbon dioxide separation device comprising: an electrolyte layer; a pair of electrodes sandwiching the electrolyte layer and disposed on the electrolyte layer; and a voltage application unit that applies a voltage between the pair of electrodes; the pair of electrodes being electrodes that allow gas to pass through, and the electrolyte layer comprising an electrolyte that can dissolve carbon dioxide and a redox compound having N-oxygen free radicals in its molecules.

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

[0010] Non-patent literature 1 proposes a battery that absorbs carbon dioxide while charging as a method for utilizing carbon dioxide.

[0011] Non-Patent Literature 2 proposes a carbon dioxide rechargeable battery incorporating a redox system. Specifically, it proposes a carbon dioxide rechargeable battery that uses poly-1,4-anthraquinone and ferrocene polyethylene at the negative and positive electrodes, respectively.

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

[0013] Patent Document 4 discloses 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; the positive electrode is an electrode that allows gas to pass through, the electrolyte layer contains an electrolyte that can dissolve carbon dioxide and a redox compound having N-oxygen free radicals in its molecules; the separator can inhibit the passage of the redox compound and allow the electrolyte to pass through.

[0014] In devices that utilize carbon dioxide, there is a need for more efficient utilization of carbon dioxide, or for the ability to separate carbon dioxide from a carbon dioxide-containing gas in a short time, even with reduced power consumption. That is, such devices for utilizing carbon dioxide require the ability to perform carbon dioxide adsorption and desorption in a short time, even with low voltage. [Prior Art Documents] [Patent Documents]

[0015] [Patent Document 1] Japanese Patent Application Publication No. Hei 7-39752 [Patent Document 2] Japanese Patent Application Publication No. 2015-36128 [Patent Document 3] Japanese Patent Application Publication No. 2018-1131 [Patent Document 4] International Publication No. 2022 / 185903 [Non-Patent Document]

[0016] [Non-Patent Literature 1] Aliza Khurram et al., “Tailoring the Discharge Reaction in Li-CO2 Batteries through Incorporation of CO2 Capture Chemistry”, Journal 2, 2649-2666, December 19, 2018 [Non-Patent Literature 2] Sahag Voskian et al., “Faradaic electro-swing reactive adsorption for CO2 Capture”, Energy & Environmental Science, 2019, 12, 3530-3547 [Summary of the Invention]

[0017] This invention was made in view of the relevant circumstances, and its object is to provide a carbon dioxide adsorption battery that can "adsorb carbon dioxide from a gas containing carbon dioxide and charge it, and desorb the carbon dioxide during discharge" even at low voltage and in a short time. Furthermore, the object of this invention is to provide a charging and discharging device equipped with the carbon dioxide adsorption battery.

[0018] One embodiment of the present invention is a carbon dioxide adsorption battery, which includes 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 that can dissolve carbon dioxide and a compound that can adsorb and desorb carbon dioxide through an electrochemical reaction; the negative electrode is an electrode that allows gas to pass through, and the positive electrode has a porous electrode containing an electrolyte.

[0019] The above and other objects, features and advantages of the present invention should be clearly understood from the following detailed description and drawings.

Implementation Method

[0021] [Forms for Implementing the Invention] The following describes forms of implementation of the present invention, but the present invention is not limited thereto.

[0022] [Carbon Dioxide Adsorption Battery] A first embodiment of the carbon dioxide adsorption battery 10 of the present invention, as shown in Figures 1 and 2, 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 includes an electrolyte (first electrolyte) capable of dissolving carbon dioxide and a compound capable of adsorbing and desorbing carbon dioxide through an electrochemical reaction. The separator 13 can inhibit the passage of the compound capable of adsorbing and desorbing carbon dioxide through an electrochemical reaction, while allowing the electrolyte to pass through. That is, the insulating material 13 makes it more difficult for the compound that can adsorb and desorb carbon dioxide through an electrochemical reaction to pass through than the electrolyte. Preferably, the insulating material 13 allows the electrolyte to pass through but prevents the compound that can adsorb and desorb carbon dioxide through an electrochemical reaction from passing through. The negative electrode 12 is an electrode that allows gas to pass through. Specifically, it allows gas flowing in the flow path 15 to pass through and contact the electrolyte layer 14. The positive electrode 11 has a porous electrode 11a containing an electrolyte (second electrolyte). The second electrolyte can also be an electrolyte capable of dissolving carbon dioxide. Furthermore, the first electrolyte is the electrolyte contained in the electrolyte layer 14 (described later), and the electrolyte contained in the porous electrode (the second electrolyte) can be an electrolyte with the same composition as the electrolyte layer 14, or it can be an electrolyte with other compositions. Here, the porous electrode is an electrode with a large specific surface area, specifically an electrode with a BET specific surface area of ​​10 m² / g or more. The positive electrode 11 only needs to have a porous electrode 11a. For example, it can be an electrode composed of the porous electrode 11a, as shown in Figures 1 and 2. It can also be a positive electrode having a current collector 11b and the porous electrode 11a located on the surface of the current collector 11b on the side of the insulating material 13. Furthermore, the porous electrode 11a contains an electrolyte, for example, it can contain electrolyte contained in the electrolyte layer 14 passing through the insulating material 13. Also, the porous electrode 11a may or may not contain compounds that can adsorb and desorb carbon dioxide through electrochemical reactions, nor is it necessary to include them. Moreover, the porous electrode 11a does not need to contain not only compounds that can adsorb and desorb carbon dioxide through electrochemical reactions, but also redox compounds. In this carbon dioxide adsorption battery 10, since the porous electrode 11a may not contain the redox compound, it is preferable that the porous electrode 11a contains an electrolyte but does not contain the redox compound. As described above, the positive electrode 11 is disposed on one side of the separator 13. Specifically, the porous electrode 11a is preferably disposed in contact with the separator 13.Furthermore, as described above, the electrolyte layer 14 is disposed on the other side of the insulating material 13, and is configured to contact the insulating material 13. The flow path 15 is not particularly limited as long as it allows gas flow. The flow path 15 may also be equipped with a valve 18 as needed. In addition, the figure only shows a valve that is closed to restrict gas flow within the flow path 15. Specifically, the valve 18 is not shown in Figure 1, but is shown in Figure 2.

[0023] In addition, Figures 1 and 2 are schematic cross-sectional views showing an example of the configuration of a carbon dioxide adsorption battery (the carbon dioxide adsorption battery 10) according to an embodiment of the present invention. Figure 1 shows the carbon dioxide adsorption battery 10 being charged, and Figure 2 shows the carbon dioxide adsorption battery 10 being discharged.

[0024] When charging the carbon dioxide adsorption battery 10, as shown in FIG1, a voltage is applied between the positive electrode 11 and the negative electrode 12 (between the pair of electrodes formed by the positive electrode 11 and the negative electrode 12) such that the potential of the negative electrode 12 is lower than the potential of the positive electrode 11. Specifically, this voltage is applied to make the compound contained in the electrolyte layer become capable of adsorbing carbon dioxide due to an electrochemical reaction. The charging of the carbon dioxide adsorption battery 10 is not particularly limited as long as the voltage can be applied in the aforementioned manner. For example, as shown in FIG1, charging of the carbon dioxide adsorption battery 10 can be performed by means of a voltage application section 16, which applies a voltage between the pair of electrodes formed by the positive electrode 11 and the negative electrode 12 such that the potential of the negative electrode 12 is lower than the potential of the positive electrode 11. The discharging of the carbon dioxide adsorption battery 10 is not particularly limited, and examples include discharging by electrically connecting the positive electrode 11 and the negative electrode 12. As shown in FIG2, the discharge of the carbon dioxide adsorption battery 10 can be exemplified by, for example, the discharge performed by setting a resistor 17 between a pair of electrodes consisting of the positive electrode 11 and the negative electrode 12.

[0025] As shown in FIG. 1, when a gas containing carbon dioxide is allowed to flow through the flow path 15, the gas passes through the negative electrode 12 and contacts the electrolyte layer 14. Since the electrolyte layer 14 contains an electrolyte that can dissolve carbon dioxide, as described above, the carbon dioxide contained in the gas in contact with the electrolyte layer 14 dissolves in the electrolyte layer 14. Furthermore, the gas containing carbon dioxide is not particularly limited; any gas containing carbon dioxide and nitrogen can be cited as examples, and more specifically, air can be cited. As shown in FIG. 1, when a voltage is applied between the positive and negative electrodes in the manner described above, the compound contained in the electrolyte layer 14 becomes capable of adsorbing carbon dioxide. Therefore, the carbon dioxide dissolved in the electrolyte contained in the electrolyte layer 14 is adsorbed onto the compound contained in the electrolyte layer 14. If the carbon dioxide is adsorbed onto the compound, the carbon dioxide adsorption battery 10 becomes charged. Furthermore, since the carbon dioxide dissolved in the electrolyte is adsorbed onto the compound, the dissolution of carbon dioxide in the electrolyte is promoted, and the carbon dioxide adsorption battery 10 is appropriately in a charged state. Then, the compound with adsorbed carbon dioxide is not easily moved to the positive electrode 11 (the porous electrode 11a) side due to the separator 13. Therefore, even if the voltage is stopped applied between the positive electrode 11 and the negative electrode 12, as long as there is no electrical connection between the positive electrode 11 and the negative electrode 12 and discharge occurs, the state of carbon dioxide adsorbed onto the compound can be appropriately maintained, that is, the charged state.

[0026] Subsequently, as shown in Figure 2, if the positive electrode and the negative electrode are electrically connected and discharged, the state in which the compound can adsorb carbon dioxide disappears due to the electrochemical reaction, and the carbon dioxide adsorbed on the compound is desorbed from the compound. Therefore, in the carbon dioxide adsorption battery 10, during discharge, carbon dioxide is released from the negative electrode 12 to the flow path 15 connected to the negative electrode 12. The gas released from the carbon dioxide adsorption battery 10 during discharge is the gas adsorbed by the compound in the carbon dioxide adsorption battery 10 during charging, that is, a gas mainly composed of carbon dioxide, and therefore a gas with a very high carbon dioxide concentration. In addition, in the flow path 15, since carbon dioxide is released, in order to prevent carbon dioxide backflow, the valve 18 on the upstream side of the flow path 15 should be closed.

[0027] From this perspective, 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, thus concentrating carbon dioxide.

[0028] Furthermore, in this carbon dioxide adsorption battery 10, by applying the voltage between the positive electrode 11 and the negative electrode 12, charge compensation (specifically, charge compensation such as that of a capacitor) without the accompanying electrochemical reaction also occurs in the positive electrode 11. Also, in this carbon dioxide adsorption battery 10, since the positive electrode 11 has the porous electrode 11a, the surface area of ​​the positive electrode 11 is large, allowing for appropriate charge compensation. Because the resistance during this charge compensation is lower than that accompanying the electrochemical reaction, it is advantageous to operate at a low voltage (i.e., low power consumption).

[0029] As can be seen from the above, the carbon dioxide adsorption battery 10 can perform "adsorption of carbon dioxide from a gas containing carbon dioxide and charging, and desorption of carbon dioxide during discharge" even at low voltage in a short time.

[0030] In this carbon dioxide adsorption battery 10, charging and discharging can be performed on the positive electrode 11 side even if carbon dioxide adsorption and desorption do not occur as described above. Therefore, the porous electrode 11a may contain the redox compound as described above, but it is not necessary to contain the redox compound. Furthermore, not only the porous electrode 11a, but also the separator 13 on the positive electrode 11 side may contain the redox compound, but it is not necessary to contain the redox compound. Also, the separator 13 on the positive electrode 11 side may not contain the redox compound, so it may contain an electrolyte but not the redox compound. Since the separator 13 on the positive electrode 11 side does not need to contain the redox compound, the content of the redox compound should be low. Specifically, in this carbon dioxide adsorption battery 10, the capacity of the separator 13 on the positive electrode 11 side derived from the redox compound is also less than the capacity of the separator 13 on the negative electrode 12 side derived from the redox compound. That is, the capacity of the redox compound originating from the separator 13 on the positive electrode 11 side should be less than the capacity of the redox compound originating from the separator 13 on the negative electrode 12 side. More specifically, the ratio of the capacity of the separator 13 originating from the redox compound on the positive electrode 11 side to the ratio of the capacity of the separator 13 originating from the redox compound on the negative electrode 12 side is preferably 0-20%, more preferably 0-10%, even more preferably 0-5%, even more preferably 0-3%, and most preferably 0-1%. Thus, even if the amount of the separator 13 on the positive electrode 11 side that satisfies the capacity relationship includes the redox compound, or even if it does not contain the redox compound, the carbon dioxide adsorption battery 10 can still "adsorb carbon dioxide from a gas containing carbon dioxide and charge it, and desorb the carbon dioxide during discharge". Furthermore, since the electrolyte layer 14 contains compounds that can adsorb and desorb carbon dioxide through an electrochemical reaction, as described above, the carbon dioxide adsorption battery 10 contains redox compounds. That is, in the carbon dioxide adsorption battery 10, at least the electrolyte layer 14 contains redox compounds that can adsorb and desorb carbon dioxide through an electrochemical reaction. Therefore, in the carbon dioxide adsorption battery 10, it is preferable that the redox compound is contained in an amount sufficient to satisfy the capacity relationship, rather than the redox compound being contained in the separator 13 on the negative electrode 12 side. Furthermore, examples of redox compounds include compounds that can adsorb and desorb carbon dioxide through an electrochemical reaction; however, there is no particular limitation as long as the compound reacts by accepting or transferring electrons in a chemical reaction.

[0031] Here, the capacity of the redox compound originating from the separator 13 on the negative electrode 12 side is, for example, the capacity of the redox compound originating from the separator 13 on the negative electrode 12 side. This capacity is generated during the period when the positive electrode 11 releases electrons, compared to the capacity of the redox compound on the negative electrode 12 side receiving electrons. Furthermore, the redox compound on the negative electrode 12 side refers to all the redox compounds on the negative electrode 12 side relative to the separator 13. Specifically, in the case of the carbon dioxide adsorption battery 10 shown in FIG. 1, it refers to all the redox compounds on the left side relative to the separator 13. More specifically, the redox compound on the negative electrode 12 side relative to the separator 13 refers to the sum of the redox compounds present inside the negative electrode 12 and in the region between the separator 13 and the negative electrode 12, such as the electrolyte layer 14. The capacity of the redox compound in the negative electrode 12 relative to the insulating material 13 can be determined from the type and amount of the redox compound present in the negative electrode 12 relative to the insulating material 13.

[0032] The capacity of the redox compound originating from the separator 13 on the positive electrode 11 side is, for example, the capacity of the redox compound originating from the separator 13 on the positive electrode 11 side. This capacity is generated during the period when the redox compound on the positive electrode 12 side releases electrons and becomes oxidized. Furthermore, the redox compound originating from the separator 13 on the positive electrode 11 side refers to all the redox compounds originating from the separator 13 on the positive electrode 11 side. Specifically, in the case of the carbon dioxide adsorption battery 10 shown in FIG. 1, it refers to all the redox compounds originating from the separator 13 on the right side. More specifically, the redox compound originating from the separator 13 on the positive electrode 11 represents 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 of the redox compound originating from the insulating material 13 on the positive electrode 11 side can be determined from the type and amount of the redox compound present on the positive electrode 11 side relative to the insulating material 13.

[0033] (Negative Electrode) The negative electrode 12 is not particularly limited as long as it is an electrode that allows gas to pass through. That is, the negative electrode 12 can be any conductive component that allows gases such as carbon dioxide to pass through and allows current to flow into the electrolyte layer 14 in contact with the negative electrode 12. Furthermore, the negative electrode 12 is preferably a porous body that has conductivity that does not impede electron movement, can store charge, has excellent gas permeability, and has a large gas contact area. Examples of the negative electrode 12 include electrodes made of porous conductive materials and electrodes made of porous bodies containing conductive materials. Examples of the porous conductive materials include porous metal layers, porous bodies containing metal fibers, porous bodies containing conductive fibers, porous bodies containing carbon as the main component, and porous bodies made of carbon. Examples of the carbon include activated carbon such as graphite, carbon nanotubes, and activated carbon fibers, and carbonaceous materials such as carbon fibers. As a porous body containing carbon, it is preferable to form the carbonaceous material into a cloth or felt-like structure. Examples include: a structure containing the carbonaceous material and a resin to form a cloth or felt-like structure. Examples of resins include: styrene-butadiene rubber and carboxymethyl cellulose. As a porous body containing metal fibers, examples include: woven fabrics containing metal fibers, knitted fabrics containing metal fibers, and woven fabrics containing metal fibers. As a porous body containing conductive fibers, examples include: woven fabrics containing conductive fibers, knitted fabrics containing conductive fibers, and woven fabrics containing conductive fibers. Examples of conductive fibers include: fibers coated with metal. Furthermore, as a coating method, plating can be used. That is, as a conductive fiber, examples include: plated fibers. As a porous conductive material, these can be used alone or in combination. That is, the negative electrode 12 can be an electrode composed of a single conductive material among the porous conductive materials, or it can be an electrode composed of a combination of two or more conductive materials. Furthermore, examples of conductive materials included in the porous body include: metal fibers, conductive fibers, metal particles, conductive ceramics, graphite, carbon nanotubes, activated carbon fibers, and other carbonaceous materials such as activated carbon and carbon fibers. Examples of metal fibers and metal particles include, for example, copper and silver. The porous body containing the metal fibers can also be a porous conductive material. Furthermore, the conductive material is preferably graphite, carbon nanotubes, carbon black such as acetylene black, activated carbon, and carbon fibers; from the viewpoint of corrosion resistance and specific surface area, activated carbon such as activated carbon fibers is more preferred. This porous metal layer system forms a metal layer with a large number of pores. Furthermore, from the viewpoint of excellent air permeability, it is preferable that the entire porous metal layer has these pores. Furthermore, as a method for obtaining the porous metal layer, there are no particular limitations as long as it is a method (porosification method) that performs a process to form a large number of pores on a metal layer that has not yet formed the pores (the metal layer before the pores are formed).Examples of methods include physical methods such as cutting, grinding, and sandblasting, and chemical methods such as electrolytic etching or electroless etching using acid or alkali etching solutions. Furthermore, as a method of creating pores, each of the above methods can be performed individually or in combination. Also, from the viewpoint of increasing surface area, chemical methods are preferred to make the formed pores (micropores) more compact (forming denser pores). Furthermore, the material of the metal layer is not particularly limited, and examples include aluminum, copper, silver, gold, iron, titanium, molybdenum, tungsten, nickel, and alloys thereof. From the viewpoint of price and processability, aluminum is preferred as the material of the metal layer. Furthermore, the metal layer before forming the pores is preferably aluminum foil. Furthermore, the conductive material can be used alone or in combination. Furthermore, the negative electrode 12 is preferably a carbon-based electrode using activated carbon or carbon fibers, or a high-porosity electrode using needle-shaped conductive materials. Furthermore, examples of the negative electrode 12 include carbon sheets, carbon cloth, and carbon paper. Among the electrodes exemplified above, the negative electrode 12 is preferably made of a conductive material selected from at least one of the group consisting of metal fibers, conductive fibers, metal particles, conductive ceramics, graphite, carbon nanotubes, activated carbon, and carbon fibers. It can be considered that with such an electrode, the negative electrode 12 can not only more appropriately apply a voltage between itself and the positive electrode 11, but also more appropriately allow carbon dioxide to pass through. Therefore, by using the electrode described above as the negative electrode 12, a carbon dioxide adsorption battery can be obtained that can more appropriately adsorb carbon dioxide from a gas containing carbon dioxide during charging and more appropriately release carbon dioxide during discharging.

[0034] The negative electrode 12 may also include a current collector. That is, the negative electrode 12 may be made of the porous material, or it may include both the porous material and the current collector. The current collector is not particularly limited as long as it does not obstruct the passage of gas. For example, the current collector may be made of a conductive material and have an opening within a range that does not obstruct the passage of gas. More specifically, the current collector may be made of a metal such as mesh metal, stamped metal, or expanded metal, or it may be a conductive material made by plating a fabric or non-woven fabric made of natural or synthetic fibers. For example, stainless steel, iron, nickel, titanium, and copper may be used as the metal that can be used as the current collector.

[0035] In the electrode comprising the porous body and the current collector, the porous body and the current collector are preferably integrally formed, and the method of integral formation is not particularly limited. As a method for integral formation, the porous body and the current collector can be partially integrally formed by methods such as ultrasonic welding and plasma welding to ensure conductivity. Alternatively, the integrally formed porous body and the current collector can also be conductive by having a conductive material such as a conductive adhesive separating them. The conductive material is not particularly limited; for example, materials formed by dispersing metal microparticles such as silver, gold, and nickel, carbon-based conductive materials, and conductive polymers can be used.

[0036] The specific surface area of ​​the negative electrode 12 is not particularly limited. For example, based on the BET specific surface area, it is preferably 1 m² / g or more, more preferably 100 m² / g or more, and even more preferably 500 m² / g or more. From the viewpoint of gas permeability, the BET specific surface area of ​​the negative electrode 12 should be large, but from the perspective of the strength of the negative electrode 12, it is preferably 3000 m² / g or less, more preferably 2500 m² / g or less, and even more preferably 2000 m² / g or less. Therefore, the BET specific surface area of ​​the negative electrode 12 is preferably 1 to 3000 m² / g, more preferably 100 to 2500 m² / g, and even more preferably 500 to 2000 m² / g. If the BET specific surface area of ​​the negative electrode 12 is too small, the gas permeability will decrease, and there is a tendency for carbon dioxide to be obstructed. Furthermore, if the BET specific surface area of ​​the negative electrode 12 is too large, there is a tendency for insufficient electrode strength, etc. From this perspective, as long as the BET specific surface area of ​​the negative electrode 12 is within the aforementioned range, carbon dioxide adsorption and release can be achieved for a long period, allowing it to be used as a carbon dioxide battery for an extended period. In addition, the BET specific surface area is a specific surface area measured by the BET method, which can be measured using known methods. Examples of methods for measuring the BET specific surface area include, for instance, measuring nitrogen adsorption isotherms and calculating from the obtained adsorption isotherms; more specifically, methods for measuring the specific surface area of ​​powders (solids) by gas adsorption according to JIS Z8830:2013 can be cited.

[0037] As described above, the negative electrode 12 is a conductive component that allows current to flow into the electrolyte layer 14 in contact with the negative electrode 12. Ideally, its surface resistance should be as low as possible, for example, preferably 1 kΩ / sq or less, and more preferably 200 Ω / sq or less. Furthermore, while a lower surface resistance is preferable for the negative electrode 12, the practical limit is 1 Ω / sq, and it is mostly around 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. With an electrode possessing this surface resistance value, carbon dioxide can be appropriately separated as current flows into the electrolyte layer 14.

[0038] The thickness of the negative electrode 12 is not particularly limited, but it is preferably a thickness that can adsorb carbon dioxide and appropriately prevent electrolyte leakage. The thickness of the negative electrode 12 is preferably 20 μm to 10 mm, and more preferably 50 μm to 5 mm. If the negative electrode 12 is too thin, the electrode strength tends to become insufficient. Furthermore, if the negative electrode 12 is too thick, gas permeability decreases, and the passage of carbon dioxide tends to be obstructed. Therefore, if the thickness of the negative electrode 12 is within the above range, carbon dioxide separation can be achieved over a long period.

[0039] (Positive Electrode) The positive electrode 11 only needs to have a porous electrode 11a containing an electrolyte. For example, it can be an electrode composed of the porous electrode 11a, as shown in Figures 1 and 2. It can also be a positive electrode having a current collector 11b and the porous electrode 11a located on the surface of the current collector 11b on the side of the insulating material 13. Furthermore, the positive electrode 11 may also have layers other than the porous electrode 11a and the current collector 11b for the purpose of maintaining strength, etc. Furthermore, the porous electrode 11a contains an electrolyte. Examples of such electrolytes include the electrolyte contained in the electrolyte layer 14, and examples of electrolytes contained in the electrolyte layer 14 that pass through the insulating material 13.

[0040] When the voltage is applied to the positive electrode 11, the porous electrode 11a is not particularly limited in that it can perform charge compensation without the accompanying electrochemical reaction as long as appropriate. Examples of porous electrodes 11a include electrodes capable of adsorbing anionic species from the electrolyte contained in the electrolyte. That is, examples of porous electrodes 11a include electrodes made of a porous material that can adsorb anionic species from the electrolyte and allow current to flow. Furthermore, the porous electrode 11a is preferably a porous material that has conductivity that does not impede electron movement, can store charge, and has a large contact area with the electrolyte. Examples of porous electrodes 11a include electrodes made of the same material as the negative electrode 12. More specifically, examples of the porous electrode 11a include electrodes made of porous conductive materials and electrodes containing conductive materials and made of porous bodies. Examples of the porous conductive materials include porous bodies containing conductive fibers, porous bodies containing carbon as the main component, and porous bodies made of carbon. Examples of the carbon include carbon black such as graphite, carbon nanotubes, acetylene black, activated carbon such as activated carbon fibers, and carbonaceous materials such as carbon fibers. Preferably, the porous body containing the carbon is formed into a cloth or felt-like structure; examples include those containing the carbonaceous material and resin and forming a cloth or felt-like structure. Examples of the resin include styrene-butadiene rubber and carboxymethyl cellulose. Examples of the porous bodies containing conductive fibers include woven fabrics containing conductive fibers, knitted fabrics containing conductive fibers, and woven fabrics containing conductive fibers. Examples of the conductive fibers include fibers coated with metal. Furthermore, methods of coating can include plating, etc. That is, as the conductive fiber, examples include plated fibers. As the porous conductive material, these can be used alone, or two or more can be used in combination. That is, as the porous electrode 11a, among these porous conductive materials, it can be an electrode composed of a single conductive material, or it can be an electrode composed of a combination of two or more conductive materials. Furthermore, as the conductive material contained in the porous body, examples include: metal fibers, conductive fibers, metal particles, conductive ceramics, graphite, carbon nanotubes, activated carbon fibers, and other activated carbon and carbonaceous materials such as carbon fibers. Examples of metal fibers and metal particles include those containing copper and silver. The porous body containing the metal fibers can also be a porous conductive material. Furthermore, the preferred conductive material is carbon black such as graphite, carbon nanotubes, and acetylene black, as well as activated carbon such as activated carbon fiber or activated carbon powder, and carbonaceous materials such as carbon fibers. From the viewpoint of corrosion resistance and specific surface area, activated carbon such as activated carbon fiber or activated carbon powder is even more preferred. Moreover, the conductive material can be used alone or in combination of two or more types.Furthermore, the porous electrode 11a is preferably a carbon-based electrode using activated carbon or carbon fiber, or an electrode with high porosity using needle-shaped conductive material. 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 made of a porous material comprising at least one material selected from the group consisting of conductive ceramics, graphite, carbon nanotubes, activated carbon, and carbon fibers. It can be considered that if the positive electrode 11 has such a porous electrode 11a, not only can a voltage be applied more appropriately between the positive electrode 11 and the negative electrode 12, but charge compensation without the accompanying electrochemical reaction can also be performed more appropriately. Therefore, if the positive electrode 11 has such a porous electrode 11a, a carbon dioxide adsorption battery can be obtained that can efficiently perform "adsorption of carbon dioxide from a gas containing carbon dioxide and charging, and desorption of carbon dioxide during discharge" and can be driven at a lower voltage (i.e., low power consumption).

[0041] Because the porous electrode 11a is porous, the adsorption capacity of anionic species is increased, thus allowing for driving at a lower voltage. The larger the specific surface area of ​​the porous electrode 11a, the lower the driving voltage. That is, the larger the specific surface area of ​​the porous electrode 11a, the more anionic species are adsorbed, and therefore a lower driving voltage can be used. Therefore, the specific surface area of ​​the porous electrode 11a, for example, is 10 m² / g or more in terms of BET specific surface area, preferably 50 m² / g or more, more preferably 100 m² / g or more, even more preferably 300 m² / g or more, particularly preferably 500 m² / g or more, and extremely preferably 800 m² / g or more. 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. Therefore, the BET specific surface area of ​​the porous electrode 11a is preferably below 3000 m² / g, more preferably below 2500 m² / g, and even more preferably below 2300 m² / g. Thus, the BET specific surface area of ​​the porous electrode 11a is preferably 10–3000 m² / g, more preferably 50–3000 m² / g, even more preferably 100–3000 m² / g, particularly preferably 300–2500 m² / g, especially preferably 500–2300 m² / g, and most preferably 800–2300 m² / g. Furthermore, the BET specific surface area of ​​the porous electrode 11a is preferably greater than that of the negative electrode 12. As the positive electrode 11, when the current collector 11b is included, considering the reduced necessity for strength and other factors, it is preferable that its BET specific surface area is larger than that of the negative electrode 12. Furthermore, the BET specific surface area is the specific surface area measured by the BET method, which can be determined by known methods. Examples of methods for measuring the BET specific surface area include: measuring nitrogen adsorption isotherms and then calculating from the obtained adsorption isotherms; more specifically, methods for determining the specific surface area of ​​powders (solids) by gas adsorption according to JIS Z8830:2013 can be cited.

[0042] The average pore size of the porous electrode 11a is preferably less than 50 nm, more preferably less than 20 nm, even more preferably less than 10 nm, even more preferably less than 5.0 nm, and particularly preferably less than 3.0 nm. Furthermore, the average pore size 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 size 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 size can be calculated, for example, by assuming the pores are cylindrical and using the BET specific surface area and the total pore volume obtained from the nitrogen adsorption isotherm, by the following formula. Average pore size (nm) = 4 × total pore volume (nm³ / g) / specific surface area (nm² / g)

[0043] However, this method for measuring the average pore size is suitable for measuring pores smaller than 50 nm. Therefore, in electrodes with a total pore volume of less than 0.1 cm3 / g, i.e., less than 50 nm, the pores are considered to be mainly interparticle or interfiber spaces, and the average pore size is considered to be greater than 50 nm.

[0044] The smaller the surface resistivity of the porous electrode 11a, the better; for example, it is preferably 1 kΩ / sq or less, and more preferably 200 Ω / sq or less. Furthermore, while a smaller surface resistivity is preferable, the actual limit is 1 Ω / sq, and it is mostly about 10 Ω / sq or more. Therefore, the surface resistivity 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 it is preferably a thickness that can adsorb anionic species originating from the electrolyte and appropriately prevent electrolyte leakage. The thickness of the porous electrode 11a is preferably 20 μm to 10 mm, and more preferably 50 μm to 5 mm. If the porous electrode 11a is too thin, the electrode strength and other properties tend to become insufficient.

[0046] The positive electrode 11 may also include a current collector 11b, as described above. The current collector 11b is not particularly limited as long as it is made of a conductive material, and examples include those identical to the current collector of the negative electrode 12. Examples of current collectors include metal foil, mesh metal, stamped metal, and expanded metal, etc. Metals that can be used as the current collector include, for example, stainless steel, iron, nickel, titanium, and copper.

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

[0048] The positive electrode 11 having the current collector 11b is preferably integrated with the porous electrode 11a and the current collector 11b, etc. The method of integration is not particularly limited; methods similar to those used to integrate the porous material and the current collector in the negative electrode 12 can be cited. Specifically, the integrated porous electrode 11a and the current collector 11b can be integrated by methods such as ultrasonic welding and plasma welding to partially integrate the porous electrode 11a and the current collector 11b to ensure conductivity. Furthermore, the integrated porous electrode 11a and the current collector 11b can also be made by using a conductive material such as a conductive adhesive as a medium between the porous electrode 11a and the current collector 11b to achieve conductivity. The conductive material is not particularly limited; for example, materials formed by dispersing metal microparticles such as silver, gold, and nickel, carbon-based conductive materials, and conductive polymers can be used.

[0049] (Electrolyte layer) The electrolyte layer 14 is not particularly limited as long as it contains an electrolyte that can dissolve carbon dioxide and a compound that can adsorb and desorb carbon dioxide through an electrochemical reaction. As described above, the electrolyte layer 14 is a carbon dioxide separator, which facilitates the separation of carbon dioxide through adsorption and release.

[0050] Examples of compounds included in the electrolyte layer 14 include compounds that adsorb carbon dioxide by electrolytic reduction and desorb carbon dioxide by electrolytic oxidation. Furthermore, in the carbon dioxide adsorption battery 10, the following compounds can be included: Specifically, compounds that adsorb carbon dioxide by accepting electrons when the potential between the positive electrode 11 and the negative electrode 12 is relatively low, and desorb carbon dioxide by donating electrons when the potential is relatively high. Also, examples of compounds include compounds having at least one of a quinone group and an N-oxygen free radical within their molecule. That is, specific examples of compounds include compounds having a quinone group within their molecule, compounds having an N-oxygen free radical within their molecule, and compounds having both a quinone group and an N-oxygen free radical within their molecule. Examples of compounds having a quinone group within their molecule include benzoquinone, naphthoquinone, and anthraquinone. Also, examples of compounds having an N-oxygen free radical within their molecule include compounds with two quaternary carbons bonded to the N-oxygen free radical. From a durability point of view, the compound is preferably one containing an N-oxygen radical within the molecule, and more preferably one in which two quaternary carbons are bonded to the N-oxygen radical. The compound with two quaternary carbons bonded to the N-oxygen radical is believed to inhibit the decomposition of the N-oxygen radical by removing a hydrogen radical from the carbon adjacent to the N-oxygen radical. Therefore, this compound is considered to be more suitable for the adsorption and desorption of carbon dioxide, allowing the carbon dioxide adsorption battery to further adsorb carbon dioxide from a gas containing carbon dioxide, thereby further maintaining the state of charge.

[0051] The compound is preferably non-volatile. For example, the compound becomes an oxy group by applying a voltage between the positive electrode 11 and the negative electrode 12 through the voltage application section 16, and then bonds with carbon dioxide. Specifically, in the case of quinone, the quinone group is reduced to generate an oxy group, and in the case of N-oxy group, the N-oxy group is reduced to become an N-oxy group, which then bonds with carbon dioxide. Furthermore, if the carbon dioxide adsorption battery 10 discharges, the carbon dioxide is removed and becomes an oxy group, which is then oxidized. Specifically, the oxy group generated by the reduction of the quinone group is oxidized to restore the quinone group, and the N-oxy group generated by the reduction of the N-oxy group is oxidized to restore the N-oxy group. The compound is a compound in which the quinone group and N-oxy radical are changed through oxidation-reduction. More specifically, the compound having a quinone group is electrolytically reduced as shown in formula (4) during charging, thereby adsorbing carbon dioxide as shown in formula (5). Then, the compound having a quinone group undergoes electrolytic oxidation during discharge as shown in formula (6), thereby removing the adsorbed carbon dioxide as shown in formula (7). The compound having an N-oxygen radical undergoes electrolytic reduction during charging as shown in formula (8), thereby adsorbing carbon dioxide as shown in formula (9). The compound having an N-oxygen radical undergoes electrolytic oxidation during discharge as shown in formula (10), thereby removing the adsorbed carbon dioxide as shown in formula (11). When the compound has both a quinone group and an N-oxygen radical, it undergoes electrolytic reduction during charging as shown in formulas (4) and (8), thereby adsorbing carbon dioxide as shown in formulas (5) and (9). Then, the compound undergoes electrolytic oxidation during discharge as shown in formulas (6) and (10), thereby removing the adsorbed carbon dioxide as shown in formulas (7) and (11).

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060] The compound contained in the electrolyte layer 14, on the side near the electrode with a low potential, i.e., the negative electrode 12, has carbon dioxide dissolved in the electrolyte bonded to the oxy-anion group (oxy-anion group generated by the reduction of quinone group and N-oxy-anion group formed by the reduction of N-oxy-anion group), thus promoting the dissolution of carbon dioxide in the electrolyte. Therefore, in the carbon dioxide adsorption battery 10, during charging, carbon dioxide is introduced from the negative electrode 12 side and adsorbed onto the electrolyte layer 14. That is, the compound undergoes electrolytic reduction to adsorb carbon dioxide. Therefore, in the carbon dioxide adsorption battery 10, if carbon dioxide is adsorbed onto the compound, the carbon dioxide adsorption battery is in a charged state.

[0061] While the separator 13 allows the electrolyte to pass through, it inhibits the passage of compounds that can adsorb and desorb carbon dioxide through electrochemical reactions. In other words, the separator 13 makes it more difficult for these compounds to pass through than for the electrolyte. Therefore, redox compounds, whether formed by the reduction of quinone and N-oxygen anions to oxy-anions (resulting from the reduction of quinone and the reduction of N-oxygen anions), or redox compounds already bonded to carbon dioxide, are not easily passed through the separator 13. Therefore, even after charging is stopped, as long as there is no discharge, these redox compounds are not easily passed through the separator 13, and the carbon dioxide adsorption battery 10 can maintain its charging state.

[0062] Then, if the charged carbon dioxide adsorption battery 10 is discharged, carbon dioxide is removed from the compound in the electrolyte layer 14, and the compound returns to its state before electrolytic reduction. Therefore, the carbon dioxide adsorption battery 10 can release carbon dioxide from the electrode side on the side where carbon dioxide is introduced when it discharges.

[0063] As described above, in this carbon dioxide adsorption battery 10, by including the compound in the electrolyte layer 14, even if the porous electrode 11a or the like of the positive electrode 11 does not contain the compound, it is possible to perform "adsorption of carbon dioxide from a gas containing carbon dioxide and charging, and desorption of carbon dioxide during discharge" at a low voltage and for a short time. Since the positive electrode 11 side, for example, the porous electrode 11a or the like of the positive electrode 11, may also not contain the compound, it also has the advantage of reducing the number of components.

[0064] The electrolyte is not particularly limited as long as it is an electrolyte capable of dissolving carbon dioxide. It can be an electrolyte containing both an electrolyte and a solvent, or an electrolyte containing an ionic liquid. Furthermore, the term "electrolyte capable of dissolving carbon dioxide" simply means any electrolyte other than one that does not dissolve carbon dioxide; that is, any electrolyte that slightly dissolves carbon dioxide is acceptable, and high solubility is not required. This is because, as described above, the carbon dioxide adsorption battery of this embodiment uses the bonding and debonding of carbon dioxide to the compound to adsorb and release carbon dioxide through a mechanism of "introducing carbon dioxide into the electrolyte layer during charging and releasing carbon dioxide from the electrolyte layer 14 during discharging." Therefore, it is believed that as long as carbon dioxide is slightly dissolved in the electrolyte contained in the electrolyte layer, carbon dioxide adsorption and release will occur.

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

[0066] The solvent is preferably a compound that is electrochemically stable and has a wide potential window, and can be an aqueous solvent or an organic solvent. Examples of such solvents include: water, carbonate compounds, ester compounds, ether compounds, heterocyclic compounds, nitrile compounds, and aprotic polar compounds. Examples of such carbonate compounds include: dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethyl carbonate, and propyl carbonate. Examples of such ester compounds include: methyl acetate, methyl propionate, and γ-butyrolactone. Examples of such ether compounds include: diethyl ether, 1,2-dimethoxyethane, 1,3-dimethoxysilane, tetrahydrofuran, and 2-methyl-tetrahydrofuran. Examples of such heterocyclic compounds include: 3-methyl-2-azolidinone and 2-methylpyrrolidone. Examples of such nitrile compounds include: acetonitrile, methoxyacetonitrile, propionitrile, 3-methoxypropionitrile, and valerate nitrile. Examples of such aprotic polar compounds include cyclobutane, dimethyl sulfoxide, and dimethylformamide. As a solvent, the solvents listed above can be used alone, or two or more can be used in combination. Furthermore, among the solvents listed above, carbonate compounds such as ethyl carbonate and propyl carbonate, ester compounds such as γ-butyrolactone, heterocyclic compounds such as 3-methyl-2-azolidinone and 2-methylpyrrolidone, and nitrile compounds such as acetonitrile, methoxyacetonitrile, propionitrile, 3-methoxypropionitrile, and valerate nitrile are preferred. Also, 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 include: quaternary ammonium salts, inorganic salts, and hydroxides. Examples of quaternary ammonium salts include: tetramethylammonium tetrafluoroborate, tetra-n-ethylammonium tetrafluoroborate, tetra-n-propylammonium tetrafluoroborate, tetra-n-butylammonium tetrafluoroborate, n-hexadecimaltrimethylammonium tetrafluoroborate, tetra-n-hexadecimalammonium tetrafluoroborate, tetra-n-octylammonium tetrafluoroborate, tetra-n-ethylammonium perchlorate, tetra-n-butylammonium perchlorate, and tetra-octadecylammonium perchlorate. Examples of inorganic salts include: lithium perchlorate, sodium perchlorate, potassium perchlorate, sodium acetate, potassium acetate, sodium nitrate, and potassium nitrate. Examples of hydroxides include: sodium hydroxide and potassium hydroxide. Among the electrolytes exemplified above, tetramethylammonium tetrafluoroborate, tetra-n-ethylammonium tetrafluoroborate, tetra-n-propylammonium tetrafluoroborate, tetra-n-butylammonium tetrafluoroborate, n-hexadecimaltrimethylammonium tetrafluoroborate, tetra-n-hexadecimalammonium tetrafluoroborate, tetra-n-octylammonium tetrafluoroborate, tetra-n-ethylammonium perchlorate, tetra-n-butylammonium perchlorate, tetra-octadecylammonium perchlorate, lithium perchlorate, sodium perchlorate, sodium acetate, and potassium acetate are preferred as electrolytes. More preferably, tetra-n-ethylammonium tetrafluoroborate, tetra-n-propylammonium tetrafluoroborate, tetra-n-butylammonium tetrafluoroborate, lithium perchlorate, and sodium perchlorate are preferred, and even more preferably, tetra-n-butylammonium tetrafluoroborate and lithium perchlorate are preferred. Furthermore, this electrolyte can also stabilize the carbonate or bicarbonate ions that serve as its supporting salt, thus possessing pH buffering capacity. Specific examples of electrolytes in this case include sodium bicarbonate, sodium carbonate, acetic acid, and sodium acetate. The electrolyte can be used alone or in combination with two or more of the electrolytes shown above.

[0068] As described above, the electrolyte can also be an electrolyte containing an ionic liquid (ionic liquid). If an ionic liquid is used as the electrolyte, as mentioned above, even without containing an electrolyte and a solvent, the ionic liquid can possess the functions of both. Furthermore, as the electrolyte, it is only necessary to contain an ionic liquid; it can be a liquid containing an electrolyte, a liquid containing a solvent, a liquid containing both an electrolyte and a solvent, or it can be composed of ionic liquids. Moreover, using an ionic liquid as the electrolyte is preferable because ionic liquids are less volatile and have high flame retardancy.

[0069] As for the ionic liquid, there is no particular limitation as long as it is a known ionic liquid, and examples include: imidazolium-based ionic liquids, pyridine-based ionic liquids, alicyclic amine-based ionic liquids, and azoamine-based ionic liquids. Examples of such ionic liquids include: 1-methyl-3-octyltetrafluoroborate imidazolium, 1-ethyl-3-methyltetrafluoroborate imidazolium, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methyltetrafluoroborate imidazolium, 1-decyl-3-methyltetrafluoroborate imidazolium, 1,3-dimethoxytetrafluoroborate imidazolium, and 1,3-diethoxytetrafluoroborate imidazolium. Imidazolium, 1-methyl-3-octyl hexafluorophosphate imidazoline, 1-ethyl-3-methyl hexafluorophosphate imidazoline, 1-butyl-3-methyl hexafluorophosphate imidazoline, 1-decyl-3-methyl hexafluorophosphate imidazoline, 1,3-dimethoxy hexafluorophosphate imidazoline, 1,3-diethoxy hexafluorophosphate imidazoline, and 1-ethyl-3-methylimidazoline bis(fluorosulfonylurea)imidinium, etc. Furthermore, among the ionic liquids exemplified above, 1-methyl-3-octyltetrafluoroborate imidazolonium, 1-ethyl-3-methyltetrafluoroborate imidazolonium, 1-butyl-3-methyltetrafluoroborate imidazolonium, 1-butyl-3-methylimidazolonium bis(trifluoromethylsulfonyl)imidimide, 1,3-dimethoxytetrafluoroborate imidazolonium, 1-methyl-3-octylhexafluorophosphate imidazolonium, 1-ethyl-3-methylhexafluorophosphate imidazolonium, and 1-ethyl-3-methylimidazolonium bis(fluorosulfonyl)imidimide are preferred as the ionic liquid. Furthermore, the preferred ionic liquids are 1-methyl-3-octyltetrafluoroborate imidazoline, 1,3-dimethoxytetrafluoroborate imidazoline, 1-butyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imidimide, 1-butyl-3-methylimidazoline chloride imidazoline, 1-methyl-3-octylhexafluorophosphate imidazoline, and 1-ethyl-3-methylimidazoline bis(fluorosulfonyl)imidimide, and even more preferred are 1-butyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imidimide, 1-butyl-3-methyl imidazoline chloride imidazoline, 1-methyl-3-octyltetrafluoroborate imidazoline, and 1-ethyl-3-methylimidazoline bis(fluorosulfonyl)imidimide.

[0070] In the electrolyte layer 14, the electrolyte can also be gelled. Specifically, a gelling agent can be added to the electrolyte to gel it, and a gelling electrolyte or a polymeric electrolyte can be used. Examples of gelling agents include polymers, gelling agents using polymer crosslinking reactions, polymerizable multifunctional monomers, and oleogelling agents. As for the gelling electrolyte and the polymeric electrolyte, there are no particular limitations as long as they can be used as gelling electrolytes or polymeric electrolytes. Examples include vinylidene fluoride-based polymers such as polyvinylidene fluoride and poly(vinylidene fluoride-co-hexafluoropropylene) (poly(vinylidene fluoride-co-hexafluoropropylene)), acrylic polymers such as polyacrylic acid, acrylonitrile polymers such as polyacrylonitrile, polyether polymers such as polyethylene oxide, and compounds with amide structures in their structure.

[0071] Specifically, as the compound having an N-oxygen radical, examples include: any one of the compounds represented by formula (1), formula (2), and formula (3), or a compound having a radical formed by removing a hydrogen atom from a compound represented by any one of formulas (1) to (3). A compound having a radical formed by removing a hydrogen atom from a compound represented by any one of formulas (1) to (3) is any compound having such a radical, and may be a compound bonded to other low-molecular-weight compounds or a high-molecular-weight compound.

[0072]

[0073]

[0074]

[0075] In formulas (1) to (3), Z represents -CR5R6CR7R8-, -CR9R10CR11R12CR13R14-, -(CR15R16)O-, -(CR17R18)NR27-, -(CR19R20)O(CR21R22)- or -(CR23R24)NR28(CR25R26)-. R1 to R4 each independently represent a substituent. R1 and R2 can also bond with each other to form a ring, and R3 and R4 can also bond with each other to form a ring. R5 to R28 each independently represent a hydrogen atom or a substituent.

[0076] Preferably, at least one of R1 to R4 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 formed by two quaternary carbons bonded to the N-oxygen free radical. Also, the compound is preferably a compound formed by two quaternary carbons bonded to the N-oxygen free radical, or a compound having a group formed by the removal of a hydrogen atom from the compound. It can be considered that such a compound is prone to redox reactions due to the N-oxygen free radical, and carbon dioxide can be more appropriately adsorbed and released by the compound. Therefore, by including such a compound in the electrolyte layer, a carbon dioxide adsorption battery can be obtained that can more appropriately adsorb carbon dioxide from a gas containing carbon dioxide during charging and more appropriately release carbon dioxide during discharging.

[0077] Z in the compounds represented by formulas (1) to (3) is preferably -CR5R6CR7R8-, -CR9R10CR11R12CR13R14-, -(CR19R20)O(CR21R22)- and -(CR23R24)NR28(CR25R26)-.

[0078] Examples of substituents in R1 to R28 include: hydrocarbon groups with 1 to 30 carbon atoms, hydroxyl groups with 1 to 10 carbon atoms, hydroxyl groups (hydroxyl groups), amine groups (unsubstituted or substituted amine groups), carboxyl groups, thiol groups, and silyl groups (unsubstituted or substituted silyl groups). Furthermore, among the substituents in R1 to R26, hydrocarbon groups with 1 to 30 carbon atoms, hydroxyl groups, and unsubstituted or substituted amine groups are preferred. Also, among the substituents in R27 and R28, hydrocarbon groups with 1 to 30 carbon atoms are preferred.

[0079] In addition, the term "may also be substituted" here includes both cases where the hydrogen atoms constituting the compound or group described below are not substituted and cases where some or all of the hydrogen atoms are substituted by substituents.

[0080] The hydrocarbon group is not particularly limited and can be linear, branched, or cyclic. Examples of such hydrocarbon groups include: methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, isobutyl, tributyl, pentyl, hexyl, octyl, decyl, dodecyl, 2-ethylhexyl, 3,7-dimethyloctyl, cyclopropyl, cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, norbornel, ammonium ethyl, benzyl, α,α-dimethylbenzyl, 1-phenylethyl, 2-phenylethyl, vinyl, propenyl, butenyl, oleyl, eicosaptenyl, docosahexaenoyl, 2,2-diphenylvinyl, 1,2,2-triphenylethylene. The compounds include 2-phenyl-2-propenyl, phenyl, 2-tolyl, 4-tolyl, 4-trifluoromethylphenyl, 4-methoxyphenyl, 4-cyanophenyl, 2-biphenyl, 3-biphenyl, 4-biphenyl, triphenyl, 3,5-diphenylphenyl, 3,4-diphenylphenyl, pentaphenylphenyl, 4-(2,2-diphenylvinyl)phenyl, 4-(1,2,2-triphenylvinyl)phenyl, piperyl, 1-naphthyl, 2-naphthyl, 9-anthrayl, 2-anthrayl, 9-phenanthyl, 1-pyrene, piperyl, tetraphenyl, and coronyl, etc. The preferred hydrocarbon group is methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, tributyl, pentyl, hexyl, octyl, decyl, dodecyl, 2-ethylhexyl, 3,7-dimethyloctyl, benzyl, α,α-dimethylbenzyl, 1-phenylethyl, 2-phenylethyl, vinyl, propenyl, butenyl, oleenyl, eicosaptenyl, docosahedral, 2,2-diphenylvinyl, 1,2,2-triphenylvinyl, 2-phenyl -2-Propylene, phenyl, 2-Tolyl, 4-Tolyl, 4-Trifluoromethylphenyl, 4-Methoxyphenyl, 4-Cyanophenyl, 2-Biphenyl, 3-Biphenyl, 4-Biphenyl, Triphenyl, 3,5-Diphenylphenyl, 3,4-Diphenylphenyl, Pentaphenylphenyl, 4-(2,2-Diphenylvinyl)phenyl, 4-(1,2,2-Triphenylvinyl)phenyl, piracene, 1-Naphthyl, 2-Naphthyl, 9-Anthracene, 2-Anthracene, and 9-Phenenyl. Furthermore, the hydrocarbon group is preferably methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, isobutyl, tributyl, pentyl, hexyl, octyl, 2-ethylhexyl, 3,7-dimethyloctyl, benzyl, or phenyl, and even more preferably methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, isobutyl, tributyl, pentyl, or hexyl.

[0081] The hydroxyl group is not particularly limited and can be linear, branched, or cyclic. Examples of such hydroxyl groups include: methoxy, ethoxy, 1-propoxy, 2-propoxy, 1-butoxy, 2-butoxy, isobutoxy, tributoxy, pentoxy, hexoxy, octoxy, decoxy, dodecoxy, 2-ethylhexoxy, 3,7-dimethyloctoxy, cyclopropoxy, cyclopentoxy, cyclohexoxy, 1-adamantoxy, 2-adamantoxy, norcamphoroxy, ethoxyammonium, trifluoromethoxy, benzoxy, α,α-dimethylbenzoxy, 2-phenylethoxy, 1-phenylethoxy, phenoxy, alkoxyphenoxy, alkylphenoxy, 1-naphthoxy, 2-naphthoxy, and pentafluorophenoxy, etc. Preferably, the hydroxyl group is methoxy, ethoxy, 1-propoxy, 2-propoxy, 1-butoxy, 2-butoxy, tributoxy, pentoxy, hexoxy, octoxy, decoxy, dodecoxy, 2-ethylhexoxy, or 3,7-dimethyloctoxy. More preferably, the hydroxyl group is methoxy, ethoxy, 1-propoxy, 2-propoxy, 1-butoxy, 2-butoxy, isobutoxy, tributoxy, pentoxy, or hexoxy.

[0082] The amino group is not particularly limited and can be linear, branched, or cyclic. Examples of such amino groups include: methylamino, ethylamino, 1-propylamino, 2-propylamino, 1-butylamino, 2-butylamino, isobutylamino, tributylamino, pentamino, hexamino, octamino, decamino, dodecamino, 2-ethylhexylamino, 3,7-dimethyloctamino, cyclopropylamino, cyclopentamino, cyclohexylamino, 1-adamantaneamino, 2-adamantaneamino, norcamphenamino, ammonium ethylamino, trifluoromethylamino, benzamino, α,α-dimethylbenzamino, 2-phenylethylamino, 1-phenylethylamino, aniline, alkoxyaniline, alkylaniline, 1-naphthylamino, 2-naphthylamino, and pentafluoroaniline. Preferably, the amino group is methylamino, ethylamino, 1-propylamino, 2-propylamino, 1-butylamino, 2-butylamino, tributylamino, pentamino, hexylamino, octamino, decamino, dodecamino, 2-ethylhexylamino, and 3,7-dimethyloctamino. More particularly, the amino group is methylamino, ethylamino, 1-propylamino, 2-propylamino, 1-butylamino, 2-butylamino, isobutylamino, tributylamino, pentamino, and hexylamino.

[0083] The silicon group is not particularly limited. Examples of such silicon groups include: dimethylsilyl, diethylsilyl, diphenylsilyl, trimethylsilyl, triethylsilyl, tributyldimethylsilyl, tributyldiphenylsilyl, and trimethylsilyl.

[0084] The compound represented by formula (1) is preferably a compound with two quaternary carbons bonded to the N-oxygen radical, as described above. Thus, the site adjacent to the N-oxygen radical has a group with high steric hindrance, resulting in high radical stability and the potential to suppress radical coupling. Therefore, it is believed that by containing such a compound in the electrolyte layer, a carbon dioxide adsorption battery can be obtained that can more appropriately adsorb carbon dioxide from a gas containing carbon dioxide during charging and release carbon dioxide during discharging.

[0085] Examples of compounds represented by formula (1) include: 1,4-di(1-oxy-2,2,6,6-tetramethyl-1-piperidin-4-yloxy)xylene, 4-acetylamine-2,2,6,6-tetramethylpiperidin-1-oxy, N,N-di-tert-butyl nitride radical, N,N-diphenyl nitride radical, N,N-dinaphthyl nitride radical, N,N-di-2-methylphenyl nitride radical, N,N-di-3-methylphenyl nitride radical, N,N-di-4-methylphenyl nitride radical, N,N-di-2-ethylphenyl nitride radical, N, N-di-2-propylphenyl nitride radical, N,N-di-2-butylphenyl nitride radical, N,N-di-2-pentylphenyl nitride radical, N,N-di-2-hexylphenyl nitride radical, N,N-di-2-isopropylphenyl nitride radical, N,N-di-2-isobutylphenyl nitride radical, N,N-di-2-di-butylphenyl nitride radical, N,N-di-2-tert-butylphenyl nitride radical, N,N-di-4-tert-butylphenyl nitride radical, N,N-di-(3,5-di-tert-butyl)phenyl nitride radical, N,N-di -4-pyridyl oxynitride radical, N,N-di-4-pyridyl oxynitride 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-tetramethylpiperidinyloxy radical (TEMPO), 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy radical, 4-amino-2,2,6,6-tetramethylpiperidinyloxy radical, 4-carboxyl-2,2,6,6-tetramethylpiperidinyloxy radical, 4-methoxy-2 ,2,6,6-Tetramethylpiperidinyloxy radical, 4-sideoxy-2,2,6,6-tetramethylpiperidinyloxy radical, 4-acetylamine-2,2,6,6-tetramethylpiperidinyloxy radical, 4-octoxy-2,2,6,6-tetramethylpiperidinyloxy radical, 2,2,5,5-tetramethylpyrrolidin-oxy radical, 3-aminomethoxy-2,2,5,5-tetramethylpyrrolidin-oxy radical, 3-carboxyl-2,2,5,5-tetramethylpyrrolidin-oxy radical, 2,2,6,6-tetramethylpyrrolidin-N-oxy radical, and 2,2,6,6-tetramethylpyrrolidin-N-oxy radical, etc.

[0086] Examples of compounds represented by formula (2) include: γ-dimethyl-butyrolactam-N-oxide, ε-dimethyl-valeractam-N-oxide, 3,4-dihydroquinoline-2-one-N-oxide, 3,3-dimethylisoquinoline-1-one-N-oxide, 3,3-dimethyl-1H-indole-2(3H)-one-N-oxide, 3,3-dimethyl-isoindole-1-one-N-oxide, and N-tert-butylbenzoic acid-N-oxide, etc.

[0087] Examples of compounds represented by formula (3) include: 1α,2α-cyclohexanedicarboxyphenylimine-N-oxy, phthalimine-N-oxy, 3-methyl-phthalimine-N-oxy, 4-methyl-phthalimine-N-oxy, 4-carboxy-phthalimine-N-oxy, naphthalene-2,3-dicarboxyphenylimine-N-oxy, pyromellitic acid di-di-N-oxy, trihydroxyimino-cyanuric acid-N-oxy, trihydroxyimino-cyanuric acid-di-N-oxy, and trihydroxyimino-cyanuric acid-tri-N-oxy, etc.

[0088] As described above, the compound may also be a polymer, and examples include compounds obtained by polymerizing any of the compounds represented by formulas (1) to (3). Examples of such polymers include compounds obtained by polymerizing monomers such as 4-acryloxy-2,2,6,6-tetramethylpiperidinoxy radical, 4-methacryloxy-2,2,6,6-tetramethylpiperidinoxy radical, 3-acryloxy-2,2,6,6-tetramethylpyrrolidinoxy radical, 3-methacryloxy-2,2,6,6-tetramethylpyrrolidinoxy radical, 4-vinyloxy-2,2,6,6-tetramethylpiperidinoxy radical and 4-vinyloxy-2,2,5,5-tetramethylpyrrolidinoxy radical. Furthermore, the polymer compound can be a compound obtained by polymerizing the monomer alone, or a compound obtained by polymerizing two or more of the monomers together. Also, the polymer compound can be a compound obtained by polymerizing the compound represented by formula (1), or a copolymer obtained by copolymerizing it with copolymer monomers such as ethylene, propylene, butadiene, isoprene, styrene, and vinyl acetate. Furthermore, the copolymer monomers can be used alone, or two or more can be used in combination.

[0089] Among the compounds exemplified above, the preferred compounds are 1,4-bis(1-oxy-2,2,6,6-tetramethyl-1-piperidin-4-yloxy)xylene, 4-acetaminophen-2,2,6,6-tetramethylpiperidin-1-oxy, and poly(4-methacryloxy-2,2,6,6-tetramethylpiperidinoxy free radical). The compound can be used alone or in combination of two or more.

[0090] The compound represented by any of the formulas (1) to (3) may also be a compound synthesized by a predetermined synthetic method or a commercially available product. As for the synthetic method, there is no particular limitation as long as it is a synthetic method that can obtain a compound represented by any of the formulas (1) to (3). Examples include: a method of nitriding by oxidizing the amino group of a disubstituted amine compound.

[0091] Furthermore, the term "non-volatile" refers to a substance that does not evaporate or does not evaporate immediately at room temperature and pressure. For example, in this specification, 2,2,6,6-tetramethylpiperidine-1-oxy (TEMPO) is not non-volatile but volatile. Therefore, as a standard for non-volatileness, examples include: a boiling point at atmospheric pressure higher than the boiling point of TEMPO (193°C), preferably 200°C or higher, and more preferably 220°C or higher. Also, as a standard for non-volatileness, examples include: a vapor pressure at 20°C lower than the vapor pressure of TEMPO (20°C) by 0.4 hPa (i.e., less than 0.4 hPa), preferably lower than 0.2 hPa (i.e., less than 0.2 hPa).

[0092] Examples of compounds having a quinone group include: 1,4-benzoquinone, 1,4-naphthoquinone, 1,5-naphthoquinone, 1,8-naphthoquinone, 1,4-anthraquinone, 1,5-anthraquinone, 1,6-anthraquinone, 5,10-anthraquinone, and 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, poly-5,10-anthraquinone, etc.

[0093] The electrolyte layer 14 may also contain components other than the electrolyte and the compound. Other components contained in the electrolyte layer 14 may include, for example, polyethylene glycol, polyacrylate, polymethacrylate, and polyvinyl acetal.

[0094] In the carbon dioxide adsorption battery 10, the electrolyte layer 14 is located between the negative electrode 12 and the separator 13 and is layered. The thickness of the electrolyte layer 14 is not particularly limited, for example, preferably 0.1 μm to 2 mm, more preferably 1 μm to 1 mm. If each electrolyte layer 14 is too thin, not only will the amount of carbon dioxide fixed and the energy storage capacity decrease, but there is also a tendency for micropores, i.e., pinholes, to form in the electrolyte layer 14. If pinholes are formed, problems such as inadequate adsorption of carbon dioxide and the inflow of current that does not contribute to the adsorption of carbon dioxide may occur. Furthermore, if the electrolyte layer 14 is too thick, the diffusion of carbon dioxide already adsorbed in the electrolyte layer 14 will be slower, resulting in a difference in the amount of carbon dioxide fixed and the energy storage capacity. Therefore, during charging, it tends to become difficult to control the sufficient adsorption of carbon dioxide. The reasons for this can be attributed to the following. In this carbon dioxide adsorption battery 10, the diffusion of carbon dioxide in the electrolyte layer 14 and the diffusion of redox compounds bonded to carbon dioxide contribute more to carbon dioxide adsorption than the diffusion contributes to charging. Furthermore, if the electrolyte layer 14 is thicker, the effect of diffusion becomes greater compared to a thinner layer. Therefore, the difference in the adsorption rate of carbon dioxide between thick and thin electrolyte layers 14 is greater than the difference in the charging rate. Thus, when the electrolyte layer 14 is thin, it is easier to determine from the stored capacity that sufficient carbon dioxide has been adsorbed; conversely, when the electrolyte layer 14 is thicker, as mentioned above, due to the difference between the amount of carbon dioxide fixed and the stored capacity, it is difficult to determine from the stored capacity that sufficient carbon dioxide has been adsorbed. Therefore, it is considered that the thicker the electrolyte layer 14, the more difficult it is to determine whether sufficient carbon dioxide has been adsorbed during charging. Furthermore, for the same reason, if the electrolyte layer 14 is too thick, there is a tendency to make it difficult to determine whether sufficient carbon dioxide has been released during discharge.

[0095] The electrolyte layer 14 may also include a substrate. Examples of the electrolyte layer 14 include those formed by impregnating the substrate with an electrolyte containing the compound. Examples of the substrate include glass fiber filter paper.

[0096] As for the method of manufacturing the electrolyte layer 14, there are no particular limitations as long as the electrolyte layer 14 can be manufactured. Examples of methods where the electrolyte layer 14 includes the substrate include: dispersing or dissolving the compound in the electrolyte, and then impregnating the substrate with the electrolyte containing the redox compound. This impregnation is preferably performed while applying ultrasonic vibration to the electrolyte or the substrate. This can suppress the formation of micropores, i.e., pinholes, in the electrolyte layer 14.

[0097] (Separating Material) The separating material 13 is not particularly limited as long as it is a separating material that inhibits the passage of the compound while allowing the electrolyte to pass through. That is, the separating material 13 makes it more difficult for the compound to pass through than for the electrolyte. Furthermore, the separating material 13 is preferably one that allows the electrolyte to pass through but prevents the compound from passing through. The separating material 13 is provided to separate the electrolyte layer 14 from the porous electrode 11a in a manner that allows the electrolyte to pass through but inhibits the passage of the compound. Therefore, the positive electrode 11 and the negative electrode 12 are separated by the separating material 13. Examples of the separating material 13 include, for example, the separating materials commonly used in lithium secondary batteries, and preferably, a separating material with low resistance to ion movement relative to the electrolyte and excellent electrolyte moisture retention performance. Examples of materials for the separating material include, for example, glass fiber, polyester, polyethylene, polypropylene, and polytetrafluoroethylene (PTFE). The materials for the separating material can be used alone or in combination of two or more. Furthermore, the insulating material 13 is composed of the same material, and its form can be either non-woven or woven fabric. The pore size of the insulating material 13 is not particularly limited; for example, it is preferably 0.01–10 μm. Also, the thickness of the insulating material 13 is not particularly limited; for example, it is preferably 5–300 μm.

[0098] (Flow path) The flow path 15 is not particularly limited as long as it allows gas to flow. Examples include a flow path in which at least one of carbon dioxide adsorbed on the compound and carbon dioxide desorbed from the compound can flow. Furthermore, the flow path 15 is connected to the negative electrode 12, allowing gas passing through and exiting the negative electrode 12 to flow within it. The flow path 15 may also be equipped with a valve 18 as required.

[0099] (Voltage Application Section) As described above, the carbon dioxide adsorption battery 10 may also include the voltage application section 16. By including the voltage application section 16 in the carbon dioxide adsorption battery 10, a carbon dioxide concentration device capable of concentrating carbon dioxide can be made. That is, a carbon dioxide concentration device having the carbon dioxide adsorption battery 10 and the voltage application section 16 that applies a voltage between the positive electrode 11 and the negative electrode 12 can be obtained.

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

[0101] As shown in Figure 2, after the carbon dioxide adsorption battery 10 is charged, a resistor 17 is placed between the positive electrode 11 and the negative electrode 12 to discharge it. The resistor 17 is not particularly limited as long as it can make the carbon dioxide adsorption battery 10 discharge.

[0102] The manufacturing method of the carbon dioxide adsorption battery 10 is not particularly limited as long as the structure can be manufactured. Specific examples of manufacturing methods for the carbon dioxide adsorption battery 10 include: assembling the battery using a positive electrode 11, a negative electrode 12, a separator 13, an electrolyte layer 14, and a flow path 15, and further, depending on the requirements, using a voltage application part 16 and a resistor 17, etc., in a manner that achieves the structure shown in Figures 1 and 2 using a general assembly method.

[0103] [Other Carbon Dioxide Adsorption Batteries] The carbon dioxide adsorption battery of this embodiment is not limited to the above-described configuration as long as it has the positive electrode, the negative electrode, the electrolyte layer, and the separator. For example, it may also have one positive electrode and two negative electrodes respectively disposed on both sides of the positive electrode. Specifically, the carbon dioxide adsorption battery 20, as shown in Figures 3 and 4, includes: a positive electrode 11; two negative electrodes 12 respectively disposed on both sides of the positive electrode 11; two separators 13 respectively disposed between the positive electrode 11 and each of the negative electrodes 12; two electrolyte layers 14 disposed between each of the negative electrodes 12 and each of the separators 13; and two flow paths 15 connected to each of the negative electrodes 12. The positive electrode 11 includes the porous electrode 11a, or it can be composed of the porous electrode 11a. As shown in Figures 3 and 4, in the case where the porous electrode 11a and the current collector 11b are both present, the porous electrode 11a is provided on both sides of the current collector 11b. In this type of carbon dioxide adsorption battery 20, during charging, carbon dioxide is adsorbed onto the compounds contained in the electrolyte layers 14 that are in contact with each negative electrode 12. That is, during charging, a gas containing carbon dioxide is circulated in the two flow paths 15 containing carbon dioxide, thereby causing carbon dioxide to be adsorbed onto the compounds contained in each electrolyte layer 14, and charging is performed. Then, as shown in Figure 4, carbon dioxide can be released from each negative electrode 12 by discharging. Thus, in this carbon dioxide adsorption battery 20, carbon dioxide adsorption and desorption can occur from either negative electrode 12 side. From the above, it can be seen that this carbon dioxide adsorption battery can perform "adsorption of carbon dioxide from a gas containing carbon dioxide and charging, and desorption of carbon dioxide during discharge" in a shorter time, even at a low voltage. In addition, Figures 3 and 4 are schematic cross-sectional views showing another example of the structure of the carbon dioxide adsorption battery of the present invention (the carbon dioxide adsorption battery 20). Figure 3 shows the carbon dioxide adsorption battery 20 during charging, and Figure 2 shows the carbon dioxide adsorption battery 20 during discharging.

[0104] [Charging and Discharging Device] The charging and discharging device of the embodiment of the present invention is a charging and discharging device having two or more of the carbon dioxide adsorption batteries. As for the charging and discharging device, there is no particular limitation as long as it has two or more of the carbon dioxide adsorption batteries, and examples include the charging and discharging device 30 shown in FIG5.

[0105] The charging and discharging device 30, for example, as shown in FIG5, includes a first carbon dioxide adsorption battery 10a and a second carbon dioxide adsorption battery 10b. In the first carbon dioxide adsorption battery 10a, its negative electrode side 10a1 and positive electrode side 10a2 are connected through the voltage application part 16, thereby enabling charging. That is, in the charging and discharging device 30, the positive electrode side 10a2 of the first carbon dioxide adsorption battery 10a is connected to the voltage application part 16 by a wiring 31, and the voltage application part 16 is connected to the negative electrode side 10a1 of the first carbon dioxide adsorption battery 10a by a wiring 32, thereby enabling the first carbon dioxide adsorption battery 10a to be charged. After charging the first carbon dioxide adsorption battery 10a, the negative electrode side 10a1 of the first carbon dioxide adsorption battery 10a is connected to the negative electrode side 10b1 of the second carbon dioxide adsorption battery 10b by wiring 36, and the positive electrode side 10b2 of the second carbon dioxide adsorption battery 10b is connected to the positive electrode side 10a2 of the first carbon dioxide adsorption battery 10a by wiring 35. This allows the first carbon dioxide adsorption battery 10a to discharge and the second carbon dioxide adsorption battery 10b to be charged. After charging the second carbon dioxide adsorption battery 10b (after discharging the first carbon dioxide adsorption battery 10a), the negative electrode side 10b1 of the second carbon dioxide adsorption battery 10b is connected to the negative electrode side 10a1 of the first carbon dioxide adsorption battery 10a by wiring 34, and the positive electrode side 10a2 of the first carbon dioxide adsorption battery 10a is connected to the positive electrode side 10b2 of the second carbon dioxide adsorption battery 10b by wiring 33. This allows the second carbon dioxide adsorption battery 10b to discharge and the first carbon dioxide adsorption battery 10a to charge. Thus, by briefly charging the first carbon dioxide adsorption battery 10a, it functions as a charge-discharge device capable of repeatedly charging and discharging the second carbon dioxide adsorption battery 10b and the first carbon dioxide adsorption battery 10a. Therefore, by having two or more carbon dioxide adsorption batteries, this charge-discharge device can repeatedly charge and discharge each individual carbon dioxide adsorption battery. Therefore, this charge-discharge device becomes a high-energy-efficiency charge-discharge device. Furthermore, the charging and discharging device can separate carbon dioxide. Additionally, 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. Furthermore, Figure 5 is a schematic diagram showing an example of the configuration of a charging and discharging device according to an embodiment of the present invention.

[0106] As described above, this specification discloses various types of technologies, among which the main technologies are summarized as follows.

[0107] The first embodiment of the carbon dioxide adsorption battery of the present invention comprises: 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 comprises an electrolyte that can dissolve carbon dioxide and a compound that can adsorb and desorb carbon dioxide by electrochemical reaction; the negative electrode is an electrode that allows gas to pass through, and the positive electrode comprises a porous electrode containing an electrolyte.

[0108] Based on this configuration, a carbon dioxide adsorption battery can be provided that can perform "adsorption of carbon dioxide from a gas containing carbon dioxide and charging, and desorption of carbon dioxide during discharge" even at low voltage for a short time. The reason is believed to be as follows.

[0109] This negative electrode allows gas present around it to pass through. If gas passes through the negative electrode, the gas passing through the negative electrode comes into contact with the negative electrode side of the electrolyte layer. Therefore, if the gas present around the negative electrode contains carbon dioxide, 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 that can dissolve carbon dioxide, the carbon dioxide contained in the gas present around the negative electrode will dissolve in the electrolyte contained in the electrolyte layer.

[0110] In this carbon dioxide adsorption battery, if a voltage is applied between the positive and negative electrodes to cause the compound contained in the electrolyte layer to become capable of adsorbing carbon dioxide due to an electrochemical reaction, the carbon dioxide dissolved in the electrolyte contained in the electrolyte layer will be adsorbed onto the compound. Furthermore, since the separator material of the carbon dioxide adsorption battery inhibits the passage of the compound, the compound that has adsorbed carbon dioxide is not easily moved to the positive electrode side through the separator material.

[0111] Therefore, if the compound adsorbs carbon dioxide, the carbon dioxide adsorption battery is in a charged state. Furthermore, since the carbon dioxide dissolved in the electrolyte is adsorbed by the compound, carbon dioxide dissolution in the electrolyte is promoted, and the carbon dioxide adsorption battery can be appropriately in a charged state. Thus, as shown in FIG1, in this carbon dioxide adsorption battery, a gas containing carbon dioxide flows through a flow path connected to the negative electrode. If a voltage is applied between the positive and negative electrodes to make the compound adsorb carbon dioxide due to an electrochemical reaction, carbon dioxide can be adsorbed and charging can be performed. Also, in this carbon dioxide adsorption battery, as described above, the compound does not easily pass through the separator. Even if the voltage applied between the positive and negative electrodes is stopped, as long as there is no electrical connection between the positive and negative electrodes and no discharge, the state of carbon dioxide adsorbed by the compound can be appropriately maintained, that is, in a charged state.

[0112] Subsequently, as shown in Figure 2, if the positive electrode and the negative electrode are electrically connected and discharged, the state in which the compound can adsorb carbon dioxide disappears due to the electrochemical reaction, and the carbon dioxide adsorbed on the compound desorbs from the compound. Therefore, during discharge, carbon dioxide is released from the negative electrode into the flow path connected to the negative electrode. The gas system released from the carbon dioxide adsorption battery during discharge is the gas of the compound adsorbed in the carbon dioxide adsorption battery during charging, and therefore is a gas with a very high carbon dioxide concentration.

[0113] From this perspective, 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, thus concentrating carbon dioxide.

[0114] Furthermore, in this carbon dioxide adsorption battery, by applying the voltage between the positive and negative electrodes, charge compensation (specifically, charge compensation such as that of a capacitor) also occurs at the positive electrode without the accompanying electrochemical reaction. In this case, since the positive electrode in the carbon dioxide adsorption battery has a porous electrode and a large surface area, the charge compensation can be appropriately performed. Because the resistance of this charge compensation is lower than that accompanying the electrochemical reaction, it helps to operate at a voltage lower than that of conventional technologies (i.e., lower power consumption).

[0115] As can be seen from the above, the carbon dioxide adsorption battery can perform "adsorption of carbon dioxide from a gas containing carbon dioxide and charging, and desorption of carbon dioxide during discharge" even at low voltage in a short time.

[0116] The second embodiment of the carbon dioxide adsorption battery of the present invention is the same as the first embodiment of the present invention, wherein the carbon dioxide adsorption battery contains a redox compound, and the capacity of the separator on the positive electrode side derived from the redox compound is less than the capacity of the separator on the negative electrode side derived from the redox compound.

[0117] In this carbon dioxide adsorption battery, charging and discharging can be performed even if carbon dioxide adsorption and desorption do not occur on the positive electrode side as described above. Therefore, although the separator on the positive electrode side may also contain the redox compound, it is not necessary for it to contain the redox compound. Therefore, according to this configuration, even if the separator contains the redox compound on the positive electrode side, the capacity of the separator on the positive electrode side originating from the redox compound is less than the capacity of the separator on the negative electrode side. Therefore, whether the separator contains the redox compound on the positive electrode side or not, it is possible to "adsorb carbon dioxide from a gas containing carbon dioxide and charge it, and desorb the carbon dioxide during discharge".

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

[0119] In this carbon dioxide adsorption battery, charging and discharging can still be performed even if carbon dioxide adsorption and desorption do not occur at the positive electrode side as described above. Therefore, compared to the separator at the positive electrode side (e.g., the porous electrode provided with the positive electrode), it is not necessary to include compounds that can adsorb and desorb carbon dioxide through electrochemical reactions. Furthermore, compared to the separator at the positive electrode side, not only is it unnecessary to include compounds that can adsorb and desorb carbon dioxide through electrochemical reactions, but also, as described above, it is not necessary to include redox compounds. Therefore, according to this configuration, even if the separator at the positive electrode side does not contain redox compounds, it is possible to "adsorb carbon dioxide from a gas containing carbon dioxide and charge, and desorb the carbon dioxide during discharge".

[0120] The carbon dioxide adsorption battery of the fourth state of the present invention is a carbon dioxide adsorption battery of any one of the first to third states of the present invention, wherein the flow path is a flow path that allows at least one of the carbon dioxide adsorbed on the compound contained in the electrolyte layer and the carbon dioxide desorbed from the compound contained in the electrolyte layer to flow.

[0121] According to this configuration, during charging, the carbon dioxide adsorbed in the electrolyte layer can flow in the flow path. Furthermore, during discharging, the carbon dioxide desorbed from the compound contained in the electrolyte layer can flow in the flow path. Therefore, as described above, the carbon dioxide adsorption battery can reliably perform "adsorption of carbon dioxide from a carbon dioxide-containing gas and charging, and desorption of the carbon dioxide during discharging" even at low voltage for a short time.

[0122] The carbon dioxide adsorption battery of the fifth state of the present invention is a carbon dioxide adsorption battery of any one of the first to fourth states of the present invention, wherein if a voltage is applied between the positive electrode and the negative electrode, charging will occur and carbon dioxide will be adsorbed on the compound contained in the electrolyte layer. If the positive electrode and the negative electrode are electrically connected to discharge the battery, the carbon dioxide adsorbed on the compound contained in the electrolyte layer will be desorbed.

[0123] Based on this configuration, as described above, even with a low voltage, it is possible to "adsorb carbon dioxide from a gas containing carbon dioxide and charge it, and desorb the carbon dioxide during discharge" in a short time.

[0124] The sixth state of the present invention is a carbon dioxide adsorption battery as in any of the first to fifth states of the present invention, wherein the compound contained in the electrolyte layer is a compound that adsorbs carbon dioxide by electrolytic reduction and desorbs carbon dioxide by electrolytic oxidation.

[0125] Based on this configuration, as described above, even with a low voltage, it is possible to "adsorb carbon dioxide from a gas containing carbon dioxide and charge it, and then desorb the carbon dioxide during discharge" in a short time. The reason for this is believed to be as follows.

[0126] During charging, the compound contained in the electrolyte layer of this carbon dioxide adsorption battery undergoes electrolytic reduction to become a reduced form. Specifically, in this carbon dioxide adsorption battery, a voltage is applied between the positive and negative electrodes such that the potential of the negative electrode is lower than that of the positive electrode, which serves as the voltage at which the compound contained in the electrolyte layer becomes capable of adsorbing carbon dioxide due to an electrochemical reaction. Since the electrolyte layer is close to the negative electrode with the lower potential, the compound contained in the electrolyte layer undergoes electrolytic reduction to become a reduced form. The carbon dioxide dissolved in the electrolyte contained in the electrolyte layer bonds with the reduced form and is incorporated into the electrolyte layer. Subsequently, if discharge occurs, the compound, which has become a reduced form, undergoes electrolytic oxidation, thereby returning to its state before electrolytic reduction, and carbon dioxide is desorbed from the compound. Therefore, carbon dioxide is released from the negative electrode. In this way, the compound can appropriately undergo adsorption and desorption of carbon dioxide. Therefore, even with a low voltage, "adsorption of carbon dioxide from a gas containing carbon dioxide and charging, followed by desorption of carbon dioxide during discharge" can be performed in a short time.

[0127] The carbon dioxide adsorption battery of the seventh state of the present invention is a carbon dioxide adsorption battery of any one of the first to sixth states of the present invention, wherein the compound contained in the electrolyte layer is a compound having an N-oxygen radical in its molecule.

[0128] Based on this configuration, even at low voltage, it is possible to "adsorb carbon dioxide from a gas containing carbon dioxide and charge it, and then desorb the carbon dioxide during discharge" in a short time. The reason is believed to be as follows.

[0129] This can be attributed to the fact that if the compound contained in the electrolyte layer is a compound with an N-oxygen free radical within its molecule, it is easier to adsorb carbon dioxide through electrolytic reduction and to desorb carbon dioxide through electrolytic oxidation. More specifically, during charging, the N-oxygen free radical in the compound is reduced to an N-oxygen anion group due to the acceptance of electrons by the compound. Carbon dioxide dissolved in the electrolyte contained in the electrolyte layer readily bonds to the N-oxygen anion group, thus easily incorporating it into the electrolyte layer. Furthermore, during discharge, the N-oxygen anion group readily undergoes electrolytic oxidation upon receiving electrons from the outside, thus readily becoming an N-oxygen free radical or an N-oxygen cation group, thereby easily desorbing carbon dioxide from the compound. In this way, the compound can more effectively adsorb and desorb carbon dioxide. Therefore, even at low voltage, the carbon dioxide adsorption battery can perform "adsorption of carbon dioxide from a gas containing carbon dioxide and charging, and desorption of carbon dioxide during discharge" in a short time.

[0130] The carbon dioxide adsorption battery of the eighth state of the present invention is the same as the carbon dioxide adsorption battery of the seventh state of the present invention, wherein the compound is a compound with two quaternary carbons bonded to the N-oxygen radical.

[0131] Based on this configuration, carbon dioxide can be further adsorbed from the gas containing carbon dioxide, and the charging state can be further maintained. Therefore, this carbon dioxide adsorption battery can perform "further adsorption of carbon dioxide from the gas containing carbon dioxide, charging at the same time as adsorption, and desorption of carbon dioxide during discharge" even at a low voltage for a short time. The reason for this is believed to be as follows.

[0132] The N-oxygen radical removes a hydrogen radical from the carbon adjacent to it, thus inhibiting the decomposition of the N-oxygen radical. Therefore, it is believed that this compound can more appropriately perform the adsorption and desorption of carbon dioxide.

[0133] The carbon dioxide adsorption battery of the ninth state of the present invention is a carbon dioxide adsorption battery of any one of the states of the first to eighth states of the present invention, wherein the compound contained in the electrolyte layer is any one of the compound represented by formula (1), the compound represented by formula (2) and the compound represented by formula (3), or a compound having a radical formed by removing a hydrogen atom from the compound represented by any one of formulas (1) to (3) within its molecule.

[0134]

[0135]

[0136]

[0137] In formulas (1) to (3), Z represents -CR5R6CR7R8-, -CR9R10CR11R12CR13R14-, -(CR15R16)O-, -(CR17R18)NR27-, -(CR19R20)O(CR21R22)- or -(CR23R24)NR28(CR25R26)-, R1 to R4 each independently represent substituents, R1 and R2 can also bond to each other to form a ring, R3 and R4 can also bond to each other to form a ring, and R5 to R28 each independently represent hydrogen atoms or substituents.

[0138] Based on this configuration, the carbon dioxide adsorption battery can further adsorb carbon dioxide from a gas containing carbon dioxide, and can further maintain the state of charge. Therefore, the carbon dioxide adsorption battery can perform "further adsorption of carbon dioxide from a gas containing carbon dioxide, charging at the same time as adsorption, and desorption of carbon dioxide during discharge" even at a low voltage for a short time. This can be attributed to the fact that the compound can inhibit the decomposition of N-oxygen free radicals by removing hydrogen free radicals from carbon adjacent to N-oxygen free radicals.

[0139] The carbon dioxide adsorption battery of the 10th state of the present invention is a carbon dioxide adsorption battery of any one of the 1st to 9th states of the present invention, wherein the negative electrode is made of a conductive material comprising 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.

[0140] According to this configuration, the carbon dioxide adsorption battery can further adsorb carbon dioxide from a gas containing carbon dioxide and can further maintain the state of charge. That is, the carbon dioxide adsorption battery can perform "further adsorption of carbon dioxide from a gas containing carbon dioxide, charging simultaneously with this adsorption, and desorption of carbon dioxide during discharge" even at a low voltage for a short time. This can be attributed to the fact that the negative electrode not only applies a more appropriate voltage to the positive electrode, but also allows carbon dioxide to pass through more appropriately.

[0141] The carbon dioxide adsorption battery of the 11th state of the present invention is a carbon dioxide adsorption battery of any one of the 1st to 10th states of the present invention, wherein the porous electrode is made of a porous material comprising at least one of the group consisting of conductive ceramics, graphite, carbon nanotubes, activated carbon and carbon fibers.

[0142] Based on this configuration, it is possible to perform "adsorption of carbon dioxide from a gas containing carbon dioxide and charging, and desorption of the carbon dioxide during discharge" in a short time, and it can be driven with a lower voltage (i.e., low power consumption). This can be attributed to the fact that charge compensation, which is not accompanied by the electrochemical reaction, can be performed more appropriately in the positive electrode.

[0143] The carbon dioxide adsorption battery of the 12th state of the present invention is a carbon dioxide adsorption battery of any one of the 1st to 11th states of the present invention, wherein the specific surface area of ​​the porous electrode is 100 m2 / g or more.

[0144] Based on this configuration, it is possible to perform "adsorption of carbon dioxide from a gas containing carbon dioxide and charging, and desorption of the carbon dioxide during discharge" in a short time, and it can be driven at a lower voltage (i.e., low power consumption). This can be attributed to the fact that charge compensation, which is not accompanied by the electrochemical reaction, can be performed more appropriately in the positive electrode.

[0145] The charging and discharging device of the 13th state of the present invention comprises two or more carbon dioxide adsorption batteries as in any one of the 1st to 12th states of the present invention.

[0146] Based on this configuration, a charging and discharging device equipped with the carbon dioxide adsorption battery can be provided. Furthermore, since the charging and discharging device has two or more carbon dioxide adsorption batteries, it can repeatedly charge and discharge each individual carbon dioxide adsorption battery. Specifically, one of the carbon dioxide adsorption batteries (first battery) is first charged. Then, by discharging the first battery, another carbon dioxide adsorption battery (second battery) connected to the first battery can be charged. Then, by discharging the second battery, the first battery can be charged. Thus, it can be used as a charging and discharging device that allows for repeated charging and discharging of the first battery and the second battery by briefly charging the first battery. Therefore, the charging and discharging device becomes a high-energy-efficiency charging and discharging device. Furthermore, the charging and discharging device can repeatedly 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 low voltage.

[0147] According to the present invention, a carbon dioxide adsorption battery can be provided that can perform "adsorption of carbon dioxide from a gas containing carbon dioxide and charging, and desorption of carbon dioxide during discharge" even at low voltage for a short time. Furthermore, according to the present invention, a charging and discharging device incorporating the carbon dioxide adsorption battery can be provided.

[0148] Hereinafter, embodiments will be given to specifically illustrate the present invention, but the present invention is not limited thereto. [Embodiments]

[0149] [Example 1] <Fabrication of carbon dioxide adsorption battery> A carbon dioxide adsorption battery having the structure shown in FIG1 and FIG2 was fabricated according to the following procedure.

[0150] (Electrolyte layer) 6.5 g of poly(vinylidene fluoride-hexafluoropropylene copolymer) (Sigma-Aldrich) was added to 100.0 g of dimethylformamide (manufactured by FUJIFILM Wako Pure Chemical Co., Ltd.), and the mixture was stirred at 80°C for 3 hours to dissolve it. Then, 4-methacryloxy-2,2,6,6-tetramethylpiperidinoxy free radical (manufactured by Tokyo Chemical Industry Co., Ltd.) was added as a monomer to the resulting solution, and 24.0 g of the compound [poly(4-methacryloxy-2,2,6,6-tetramethylpiperidinoxy free radical)] (non-volatile) obtained by conventional anionic polymerization was added, and the mixture was stirred at 80°C for 3 hours to dissolve it. Then, 12.9 g of an ionic liquid [1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imidine (non-volatile) (emimFSI manufactured by Sigma-Aldrich)], which serves as an electrolyte for dissolving carbon dioxide, was added to the resulting solution. The mixture was heated to 40°C and stirred for 3 hours. A 500 μm thick liquid film was formed on a glass plate using a spreader and dried under reduced pressure at 60°C for 8 hours. The dried film was then peeled off the glass plate, resulting in a 100 μm thick dried film. This dried film was cut to dimensions of 20 mm longitudinally and 24 mm transversely and used as the electrolyte layer. The resulting electrolyte layer was visually inspected, and no micropores (pinholes) were observed.

[0151] (Positive Electrode) Activated carbon (YP-50F manufactured by Kuraray Co., Ltd.), styrene-butadiene rubber (SBR) (TRD2001 manufactured by JSR Co., Ltd.), carboxymethyl cellulose (CMC) (CELLOGEN F-BSH manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.), and acetylene black (Denka black manufactured by Denka Co., Ltd.) were mixed with water in a mass ratio of activated carbon:SBR:CMC:acetylene black = 90:3:2:5 to obtain a slurry. The obtained slurry was coated onto a 20 μm thick etched aluminum foil (manufactured by Hosen Co., Ltd.) using a rod coating method, and then dried in a glass tube oven at 120°C under reduced pressure for 7 hours to obtain a polarity-separated electrode (an electrode in which the porous electrode and the current collector are integrated). That is, a layered porous electrode formed on the etched aluminum foil (current collector). The BET specific surface area of ​​this porous electrode was measured using a nitrogen adsorption isotherm, and the result calculated from the obtained adsorption isotherm was 1500 m² / g. Furthermore, the thickness of the obtained electrode (positive electrode) was 100 μm. The obtained electrode was cut into dimensions of 30 mm longitudinally × 30 mm transversely, the ionic liquid was added, and conductive copper foil tape (used as a marker) was attached to one side of the etched aluminum foil to serve as the positive electrode.

[0152] (Negative electrode) Carbon paper (GDL35BC manufactured by SGL Carbon Japan Co., Ltd.) was cut into multiple pieces with a length of 30mm × width of 30mm. The BET specific surface area of ​​this negative electrode was measured by nitrogen adsorption isotherm, and the result was calculated from the obtained adsorption isotherm to be 4m2 / g.

[0153] Attach conductive copper foil tape (for marking) to one side of the cut carbon paper to serve as the negative electrode.

[0154] (Insulation Material) The polypropylene insulation material (Celgard #2400 manufactured by Polypore Ltd.) is cut into dimensions of 30mm in length and 30mm in width, and is used as the insulation material.

[0155] (Flow path) A polytetrafluoroethylene resin sheet is cut into dimensions of 50mm longitudinally × 50mm transversely × 5mm in thickness, and two holes are made at appropriate locations. A groove with a depth of 1mm × longitudinally × transversely and connected to the holes is carved into the cut resin sheet. This serves as the flow path.

[0156] (Carbon Dioxide Adsorption Battery) A carbon dioxide adsorption battery with the structure shown in Figures 1 and 2 is manufactured by stacking the negative electrode, the electrolyte layer, the separator soaked in the ionic liquid, and the positive electrode soaked in the ionic liquid in this order, and assembling the flow path on the negative electrode surface. Then, when the carbon dioxide adsorption battery is charged, as shown in Figure 1, a power supply serving as a voltage application part is connected to the conductive copper foil tape of the positive electrode and the conductive copper foil tape of the negative electrode. Furthermore, when the carbon dioxide adsorption battery is discharged, as shown in Figure 2, a resistor is connected to the conductive copper foil tape of the positive electrode and the conductive copper foil tape of the negative electrode.

[0157] It is known that in the carbon dioxide adsorption battery of Example 1, there is an electrolyte on the positive electrode side compared to the separator, but no redox compounds are present. Even if they are present, they are only a small amount of redox compounds that leak from the electrolyte layer through the separator. Therefore, the capacity of the separator on the positive electrode side derived from redox compounds is less than the capacity of the separator on the negative electrode side.

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

[0159] [Example 3] The polarity electrode used as the positive electrode in Example 1 was used instead of carbon paper as the negative electrode, and otherwise the same procedure was followed as in Example 1.

[0160] [Example 4] An electrolyte layer was added between the insulating material and the positive electrode soaked in the ionic liquid, and otherwise the same procedure as in Example 1 was followed.

[0161] [Example 5] The thickness of the electrolyte layer was 50 μm, and otherwise the same as in Example 4 was performed.

[0162] [Example 6] The activated carbon used in the porous electrode was changed to YP-80F manufactured by Kuraray Co., Ltd., otherwise it was carried out in the same manner as in Example 4. The BET specific surface area of ​​this porous electrode was 2100 m2 / g.

[0163] [Example 7] The activated carbon used in the porous electrode was changed to Kuraray COAL GW60 / 150D manufactured by Kuraray Inc., and otherwise carried out in the same manner as in Example 4. The BET specific surface area of ​​this porous electrode was 900 m2 / g.

[0164] [Comparative Example 1] Except for the addition of the ionic liquid [1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imidine (non-volatile)] to the positive electrode, the procedure was carried out in the same manner as in Example 1.

[0165] [Comparative Example 2] The same negative electrode as that made in Example 1 was used as the positive electrode, and the procedure was otherwise carried out in the same manner as in Example 1.

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

[0167] The specific surface area, presence or absence of ionic liquid added to the porous electrode, amount of redox compound added to the electrolyte layer on the positive electrode side, type of negative electrode, and amount of redox compound added to the electrolyte layer on the negative electrode side of the porous electrodes in Examples 1-7 and Comparative Examples 1-3 are summarized and shown in Table 1. In cases where no electrolyte layer is present, "-" is displayed in the "Amount of Redox Compound Added" column. Furthermore, for cases where the total pore volume is 0.1 cm³ / g or less, based on the above reasons, the average pore diameter is considered to be 50 nm or more, therefore "50 or more" is displayed here.

[0168] [Table 1] Positive side​ Negative electrode side Porous electrode Electrolyte layer negative electrode Electrolyte layer Specific surface area (m²) 2 / g) Total pore volume (cm 3 / g) Average pore size (nm) Ionic liquids Add to redox compounds Added amount (g) redox compounds Added amount (g) Example 1 1500 0.89 2.37 have - Carbon paper twenty four Example 2 1500 0.89 2.37 have - Carbon paper 48 Example 3 1500 0.89 2.37 have - Porous electrode twenty four Example 4 1500 0.89 2.37 have twenty four Carbon paper twenty four Example 5 1500 0.89 2.37 have 6 Carbon paper twenty four Example 6 2100 1.32 2.51 have - Carbon paper twenty four Example 7 900 0.61 2.71 have - Carbon paper twenty four Comparative Example 1 1500 0.89 2.37 none - Carbon paper twenty four Comparative Example 2 4 0.014 50 and above have - Carbon paper twenty four Comparative Example 3 4 0.014 50 and above have twenty four Carbon paper twenty four

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

[0170] (Experiment 1) First, the carbon dioxide adsorption battery was placed in an environment at room temperature (28°C), and a 2L gas bag filled with a mixture of carbon dioxide and nitrogen was installed in the orifice of the flow path. A portable carbon dioxide gas concentration meter (CGP-31 manufactured by DKK-TOA Co., Ltd.) was installed in each orifice of the flow path. The carbon dioxide concentration measured at this time was 0.4% (4000ppm). Then, by adjusting the power supply, 1.5V was applied between the positive and negative electrodes, and the battery was charged until the current reached 0.01mA, and then discharged to 0V, thereby measuring the discharge characteristics of the carbon dioxide adsorption battery. Specifically, the discharge characteristics (discharge rate characteristic evaluation) of the carbon dioxide adsorption battery were measured in the following manner.

[0171] (Evaluation of Discharge Capacity Characteristics) Using a charge-discharge test apparatus (TOSCAT manufactured by Toyo Systems Co., Ltd.), the carbon dioxide adsorption battery was charged at a constant current of 2.5mA until the voltage reached 1.5V, and then charged at a constant voltage of 1.5V until 0.01mA. Afterwards, it was discharged at a constant current (2.5mA) until 0V, and the discharge capacity (F / g) was measured at this point. Furthermore, to facilitate comparison of the efficiency of the free radical materials, the discharge capacity was calculated as the capacity per unit weight of the free radical materials.

[0172] When evaluating the discharge rate characteristics, the residual carbon dioxide concentration (CO2 concentration after charging) was measured using a portable carbon dioxide gas concentration meter (CGP-31 manufactured by DKK-TOA Co., Ltd.) installed in the flow path hole on the first electrode side after the charging was completed. Furthermore, after the discharge, the carbon dioxide concentration (CO2 concentration after discharge) was measured using a portable carbon dioxide gas concentration meter installed in the flow path hole on the first electrode side.

[0173] This result is shown in Table 2.

[0174] (Experiment 2) After charging with a constant current of 10mA until the voltage reaches 1.5V, the carbon dioxide adsorption battery was then charged with a constant voltage of 1.5V to drive it, and the changes over time were observed. The results are shown in Table 3.

[0175] [Table 2] CO2 concentration (ppm) Discharge capacity (F / g) Before charging After charging After discharge Example 1 4000 1400 3920 12.4 Example 2 4000 800 3890 12.4 Example 3 4000 1180 3820 17.7 Comparative Example 1 4000 4000 4000​ 0

[0176] [Table 3] CO2 concentration (ppm) Before driving Driver Start 10 minutes later Driver Start 20 minutes later Driver Start 30 minutes later Example 1 4000 2800 1600 1400 Example 4 4000 3400 2700 2300 Example 5 4000 3300 2600 2000 Example 6 4000 3000 2100 1700 Example 7 4000 2700 1500 1300 Comparative Example 2 4000 3600 3200 2800 Comparative Example 3 4000 3900 3800 3700 ​

[0177] As can be seen from Table 2, the carbon dioxide adsorption battery (Examples 1-3) having a positive electrode with a porous electrode containing an electrolyte, a negative electrode that allows gas to pass through, the separator, an electrolyte layer containing a compound that can dissolve carbon dioxide and adsorb and desorb carbon dioxide through an electrochemical reaction can be charged even at a relatively low voltage of 1.5V, and can also be discharged. It was then found that the carbon dioxide adsorption battery of Examples 1-3, unlike the case without this configuration (Comparative Example 1), can adsorb carbon dioxide even when charged at a relatively low voltage, and can release the adsorbed carbon dioxide during discharge.

[0178] As can be seen from Table 3, the carbon dioxide adsorption battery (Examples 1 and Examples 4-7) which has a positive electrode with a porous electrode containing an electrolyte, a negative electrode that allows gas to pass through, the separator, an electrolyte layer containing a compound that can dissolve carbon dioxide and a compound that can adsorb and desorb carbon dioxide through an electrochemical reaction, can adsorb a large amount of carbon dioxide in a short time of less than 30 minutes from the start of driving, even at a lower voltage of 1.5V, compared to the carbon dioxide adsorption battery (Comparative Examples 2 and 3) which does not use a positive electrode with a porous electrode.

[0179] As can be seen from the above, a carbon dioxide adsorption battery having "a positive electrode having a porous electrode containing an electrolyte, a negative electrode that allows gas to pass through, the insulating material, an electrolyte containing a compound that can dissolve carbon dioxide and an electrolyte layer containing a compound that can adsorb and desorb carbon dioxide through an electrochemical reaction" can perform "adsorption of carbon dioxide from a gas containing carbon dioxide and charging, and desorption of carbon dioxide during discharge" in a short time, even at low voltage.

[0180] This application is based on Japanese Patent Application No. 2024-069619, filed on April 23, 2024, the contents of which are included in this application.

[0181] In order to present the invention, it has been adequately and sufficiently described above through embodiments. However, it should be understood that variations and / or modifications to the above embodiments can be easily made by those skilled in the art. Therefore, any variations or modifications implemented by those skilled in the art that do not depart from the scope of the claims described in the patent application are to be interpreted as being included within the scope of the claims. [Possibility of Industrial Use]

[0182] According to the present invention, a carbon dioxide adsorption battery can be provided that can perform "adsorption of carbon dioxide from a gas containing carbon dioxide and charging, and desorption of carbon dioxide during discharge" even at low voltage for a short time. Furthermore, according to the present invention, a charging and discharging device equipped with the carbon dioxide adsorption battery is provided. [Simplified Explanation of the Diagram]

[0020] FIG1 is a schematic cross-sectional view showing an example of the configuration of the carbon dioxide adsorption battery according to an embodiment of the present invention during charging. FIG2 is a schematic cross-sectional view showing an example of the configuration of the carbon dioxide adsorption battery according to an embodiment of the present invention during discharging. FIG3 is a schematic cross-sectional view showing another example of the configuration of the carbon dioxide adsorption battery according to an embodiment of the present invention during charging. FIG4 is a schematic cross-sectional view showing another example of the configuration of the carbon dioxide adsorption battery according to an embodiment of the present invention during discharging. FIG5 is a schematic diagram showing an example of the configuration of the charging and discharging device according to an embodiment of the present invention.

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; the electrolyte layer comprising an electrolyte capable of dissolving carbon dioxide and a compound capable of adsorbing and desorbing carbon dioxide through an electrochemical reaction; the negative electrode being an electrode through which gas can pass; the positive electrode comprising a porous electrode containing an electrolyte; and the porous electrode being disposed in contact with the separator.

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

3. The carbon dioxide adsorption battery of claim 2, wherein the separator does not contain the redox compound on the positive electrode side.

4. The carbon dioxide adsorption battery of claim 1 or claim 2, wherein the flow path is a flow path in which at least one of the carbon dioxide adsorbed on the compound contained in the electrolyte layer and the carbon dioxide desorbed from the compound contained in the electrolyte layer can flow.

5. A carbon dioxide adsorption battery as claimed in claim 1 or claim 2, wherein if a voltage is applied between the positive and negative electrodes, charging is performed and carbon dioxide is adsorbed onto the compound contained in the electrolyte layer; if the positive and negative electrodes are electrically connected to discharge the battery, the carbon dioxide adsorbed onto the compound contained in the electrolyte layer is desorbed.

6. The carbon dioxide adsorption battery of claim 1 or claim 2, wherein the compound contained in the electrolyte layer is a compound that adsorbs carbon dioxide by electrolytic reduction and desorbs carbon dioxide by electrolytic oxidation.

7. The carbon dioxide adsorption battery of claim 1 or claim 2, wherein the compound contained in the electrolyte layer is a compound having an N-oxygen radical in the molecule.

8. The carbon dioxide adsorption battery of claim 7, wherein the compound is a compound having two quaternary carbons bonded to the N-oxygen radical.

9. The carbon dioxide adsorption battery of claim 1 or claim 2, wherein the compound contained in the electrolyte layer is any one of the compound represented by formula (1), the compound represented by formula (2) and the compound represented by formula (3), or a compound having a radical in its molecule formed by removing a hydrogen atom from the compound represented by any one of formulas (1) to (3); [In formulas (1) to (3), Z represents -CR5R6CR7R8-, -CR9R10CR11R12CR13R14-, -(CR15R16)O-, -(CR17R18)NR27-, -(CR19R20)O(CR21R22)- or -(CR23R24)NR28(CR25R26)-, R1 to R4 each independently represent substituents, R1 and R2 can also bond to each other to form a ring, R3 and R4 can also bond to each other to form a ring, and R5 to R28 each independently represent hydrogen atoms or substituents].

10. The carbon dioxide adsorption battery of claim 1 or claim 2, wherein the negative electrode is made of a conductive material comprising 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.

11. The carbon dioxide adsorption battery of claim 1 or claim 2, wherein the porous electrode is made of a porous material comprising at least one selected from the group consisting of conductive ceramics, graphite, carbon nanotubes, activated carbon and carbon fibers.

12. The carbon dioxide adsorption battery of claim 1 or claim 2, wherein the specific surface area of ​​the porous electrode is 100 m2 / g or more.

13. A charging and discharging device comprising two or more carbon dioxide adsorption batteries as claimed in claim 1 or claim 2.

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