Electrochemical cell and method for manufacturing the same

Abstract

To provide an electrochemical cell which can improve electrode performance, and a method for manufacturing the same.SOLUTION: An electrochemical cell includes a working electrode 130 for adsorbing and desorbing recovered gas by electrochemical reaction from mixed gas containing the recovered gas, and a counter electrode 140 for exchanging electrons with the working electrode 130, wherein electrode films 132 and 142 constituting at least one of the working electrode 130 and the counter electrode 140 have an active substance, a conductive auxiliary agent, and a binder, the binder contains a polymer resin, and the polymer resin is composed of carbon and a halogen element, or carbon, a halogen element, and oxygen.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to an electrochemical cell and a method for manufacturing the same.

Background Art

[0002] In Patent Document 1, an electrochemical cell used in a carbon dioxide recovery system for separating carbon dioxide from a carbon dioxide (CO2)-containing gas by an electrochemical reaction has been proposed. In Patent Document 1, in a state where a potential difference is applied between the cathode and the anode of the electrochemical cell, by supplying the carbon dioxide-containing gas to the cathode, an electrochemical reaction in which CO3 is generated from CO2 and an electrochemical reaction in which CO2 is generated from CO3 2- are carried out. 2- From CO3

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an electrochemical cell, the cathode and the anode are configured by bonding an electrode film to a current collector, which is a porous conductive member. The electrode film is composed of an active material, a conductive assistant, and a binder in addition. The binder is a binding assistant that assists in binding the current collector, the active material, the conductive assistant, etc. When the electrochemical cell is used in an EDLC (electric double layer capacitor) or a battery, PVDF (polyvinylidene fluoride), which has high solubility in a solvent and high chemical stability, is widely adopted as the binder.

[0005] However, our investigations have revealed that when an electrochemical cell is used in a carbon dioxide recovery system to recover carbon dioxide from the atmosphere, the PVDF is decomposed due to the effects of oxygen and moisture in the atmosphere. When the PVDF binder decomposes, it becomes difficult to ensure the movement of electrons between the current collector, active material, and conductive additive. In addition, the adsorbent becomes more likely to detach from the current collector, and the amount of adsorbent in the electrochemical cell tends to decrease over time. As a result, the electrode performance of the electrochemical cell deteriorates.

[0006] In view of the above points, this disclosure aims to provide an electrochemical cell capable of improving electrode performance and a method for manufacturing the same. [Means for solving the problem]

[0007] To achieve the above objective, the electrochemical cell described in claim 1 includes a working electrode (130) that performs adsorption and desorption of the gas to be recovered from a mixed gas containing the gas to be recovered by an electrochemical reaction, It comprises a counter electrode (140) that exchanges electrons with the working electrode, The gas to be recovered is carbon dioxide. The gas mixture is the atmosphere. The electrode films (132, 142) constituting at least one of the working electrode and the counter electrode have an active material, a conductive additive and a binder. The binder is It has the function of holding the active material and conductive additive in the current collector (131, 141), It contains polymer resin, To suppress the decomposition of the binder by components in the atmosphere, the polymer resin is composed of carbon and halogen elements, or carbon, halogen elements, and oxygen. The polymer resin contains at least one of FEP, PCTFE, or PFA. Occasionally, The average equivalent diameter of the polymer resin is 1 μm or less. .

[0008] According to this, since the polymer resin contained in the binder forming the electrode films (132, 142) is composed of carbon and halogen elements, or carbon, halogen elements, and oxygen, the decomposition of the binder by components contained in the mixed gas can be suppressed. As a result, it becomes possible to improve the electrode performance of the electrochemical cell.

[0009] Furthermore, claims 2 The method for manufacturing an electrochemical cell described herein involves a working electrode (130) that performs adsorption and desorption of the gas to be recovered by an electrochemical reaction from a mixed gas containing the gas to be recovered, It comprises a counter electrode (140) that exchanges electrons with the working electrode, The gas to be recovered is carbon dioxide. The gas mixture is the atmosphere. The working electrode constituent material that makes up the electrode film (132) of the working electrode is As a binder Contains polymer resin, To suppress the decomposition of the binder by components in the atmosphere, the polymer resin is composed of carbon and halogen elements, or carbon, halogen elements, and oxygen. A method for producing an electrochemical cell containing at least one of FEP, PCTFE, and PFA, Includes a working electrode forming step, The working electrode formation process is as follows: A mixing step in which the materials constituting the working electrode are mixed, The process includes a heating step in which the working electrode constituent materials mixed in the mixing step are heated to the thermal decomposition temperature of the polymer resin. fruit, In the mixing process, the polymer resin is dispersed and mixed as nanoparticles with an average circular diameter of 1 μm or less. .

[0010] According to this method, by using a polymer resin composed of carbon and halogen elements, or carbon, halogen elements, and oxygen, the decomposition of the polymer resin by components in the mixed gas can be suppressed. As a result, it becomes possible to improve the electrode performance of the electrochemical cell.

[0011] Also, the method for manufacturing an electrochemical cell according to claim 4 includes a working electrode (130) that adsorbs and desorbs a gas to be recovered by an electrochemical reaction from a mixed gas containing the gas to be recovered, and a counter electrode (140) that exchanges electrons with the working electrode. The gas to be recovered is carbon dioxide. The gas mixture is the atmosphere. The counter electrode constituent material that constitutes the electrode film (142) of the counter electrode Polyvinylferrocene is used as the counter electrode active material that exchanges electrons with the working electrode, and as a binder. contains a polymer resin. In order to suppress the decomposition of the binder by the components contained in the atmosphere, the polymer resin is composed of carbon and halogen elements, or is composed of carbon, halogen elements, and oxygen. The method for manufacturing an electrochemical cell in which the polymer resin contains at least one of FEP, PCTFE, and PFA includes a counter electrode forming step of forming a counter electrode. The counter electrode forming step includes a mixing step of mixing the counter electrode constituent material, and a compression step of compressing the counter electrode constituent material mixed in the mixing step. Without a heating process fruit, In the mixing process, the polymer resin is dispersed and mixed as nanoparticles with an average circular diameter of 1 μm or less. .

[0012] According to this, since the polymer resin contained in the counter electrode constituent material is composed of carbon and halogen elements, or is composed of carbon, halogen elements, and oxygen, it is possible to suppress the decomposition of the polymer resin by the components contained in the mixed gas. As a result, it becomes possible to improve the electrode performance of the electrochemical cell.

[0013] Note that the reference numerals in parentheses for each means described in this column and the claims indicate the correspondence with the specific means described in the embodiments described later.

Brief Description of the Drawings

[0014] [Figure 1] ​This is a conceptual diagram showing the overall configuration of the carbon dioxide capture system in the first embodiment. [Figure 2] This is an explanatory diagram showing a carbon dioxide recovery device in the first embodiment. [Figure 3] This is a cross-sectional view showing an electrochemical cell in the first embodiment. [Figure 4] This diagram shows the polymer resin contained in the binder on the working electrode side. [Figure 5] This figure shows the relationship between the number of cycles and the amount of decomposition products relative to the amount of carbon dioxide adsorbed. [Figure 6] This is an explanatory diagram illustrating the oxidative decomposition of PVDF in Comparative Example 1. [Figure 7] This figure shows the surface of the working electrode side electrode film in the first embodiment. [Figure 8] This figure shows the film structure of the working electrode side electrode film in the first embodiment. [Figure 9] This figure shows the surface of the working electrode side electrode film in Comparative Example 2. [Figure 10] This figure shows the film structure of the working electrode side electrode film in Comparative Example 2. [Modes for carrying out the invention]

[0015] The embodiments of this disclosure will be described below with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals in the drawings.

[0016] (First Embodiment) A first embodiment of this disclosure will be described with reference to the drawings. In this embodiment, the electrochemical cell of this disclosure is applied to a carbon dioxide recovery system that separates and recovers carbon dioxide from a mixed gas containing carbon dioxide. Therefore, the gas to be recovered in this embodiment is carbon dioxide.

[0017] As shown in Figure 1, the carbon dioxide recovery system 10 of this embodiment includes a compressor 11, a carbon dioxide recovery device 100, a flow path switching valve 12, a carbon dioxide utilization device 13, and a control device 14.

[0018] The compressor 11 pumps the carbon dioxide-containing gas to the carbon dioxide recovery device 100. The carbon dioxide-containing gas is a mixed gas containing carbon dioxide and other gases, and can be, for example, air. The carbon dioxide-containing gas contains at least oxygen (O2) as the gas other than carbon dioxide.

[0019] The carbon dioxide capture device 100 is a device that separates and captures carbon dioxide from a carbon dioxide-containing gas. The carbon dioxide capture device 100 emits a carbon dioxide-removed gas, or the carbon dioxide that has been captured from the carbon dioxide-containing gas. The configuration of the carbon dioxide capture device 100 will be described in detail later.

[0020] The flow path switching valve 12 is a three-way valve that switches the flow path of the exhaust gas from the carbon dioxide recovery device 100. When carbon dioxide removal gas is discharged from the carbon dioxide recovery device 100, the flow path switching valve 12 switches the exhaust gas flow path to the atmosphere side, and when carbon dioxide is discharged from the carbon dioxide recovery device 100, it switches the exhaust gas flow path to the carbon dioxide utilization device 13 side.

[0021] The carbon dioxide utilization device 13 is a device that utilizes carbon dioxide. The carbon dioxide utilization device 13 can include, for example, a storage tank for storing carbon dioxide or a conversion device for converting carbon dioxide into fuel. The conversion device can be one that converts carbon dioxide into a hydrocarbon fuel such as methane. The hydrocarbon fuel may be a gaseous fuel at room temperature and pressure, or a liquid fuel at room temperature and pressure.

[0022] The control device 14 consists of a well-known microcomputer including a CPU, ROM, and RAM, and its peripheral circuits. The control device 14 performs various calculations and processes based on a control program stored in the ROM, and controls the operation of various controlled devices. In this embodiment, the control device 14 performs operation control of the compressor 11, operation control of the carbon dioxide recovery device 100, flow path switching control of the flow path switching valve 12, and the like.

[0023] As shown in Figure 2, the carbon dioxide capture device 100 is equipped with an electrochemical cell 101. The electrochemical cell 101 has a working electrode 130, a counter electrode 140, and a separator 150. In the example shown in Figure 2, the working electrode 130, the counter electrode 140, and the separator 150 are each configured in a plate shape. In Figure 2, the working electrode 130, the counter electrode 140, and the separator 150 are shown with spaces between them, but in reality, these components are arranged to be in contact with each other.

[0024] The electrochemical cell 101 may be housed in a container (not shown). The container may be provided with a gas inlet for introducing carbon dioxide-containing gas into the container and a gas outlet for releasing carbon dioxide removal gas or carbon dioxide from the container.

[0025] The carbon dioxide recovery device 100 separates and recovers carbon dioxide from a carbon dioxide-containing gas by adsorption and desorption of carbon dioxide through an electrochemical reaction. The carbon dioxide recovery device 100 is equipped with a control power supply 120 that applies a predetermined voltage to the working electrode 130 and the counter electrode 140, and can change the potential difference between the working electrode 130 and the counter electrode 140. The working electrode 130 is the negative electrode, and the counter electrode 140 is the positive electrode.

[0026] The electrochemical cell 101 can operate by changing the potential difference between the working electrode 130 and the counter electrode 140, thereby switching between a recovery mode in which carbon dioxide is recovered at the working electrode 130 and a release mode in which carbon dioxide is released from the working electrode 130. The recovery mode is a charging mode in which the electrochemical cell 101 is charged, and the release mode is a discharge mode in which the electrochemical cell 101 is discharged.

[0027] In recovery mode, a first voltage V1 is applied between the working electrode 130 and the counter electrode 140, and electrons are supplied from the counter electrode 140 to the working electrode 130. At the first voltage V1, the working electrode potential is less than the counter electrode potential. The first voltage V1 can be, for example, in the range of 0.5 to 2.0 V.

[0028] In emission mode, a second voltage V2 lower than the first voltage V1 is applied between the working electrode 130 and the counter electrode 140, supplying electrons from the working electrode 130 to the counter electrode 140. The second voltage V2 only needs to be lower than the first voltage V1, and the relative magnitudes of the working electrode potential and the counter electrode potential are not limited. In other words, in emission mode, the working electrode potential may be less than the counter electrode potential, the working electrode potential may be equal to the counter electrode potential, or the working electrode potential may be greater than the counter electrode potential.

[0029] As shown in Figure 3, the working electrode 130 in the electrochemical cell 101 has a working electrode-side current collector 131 and a working electrode-side electrode film 132. The working electrode-side current collector 131 is connected to the control power supply 120 and is a porous conductive member that can pass carbon dioxide-containing gas through.

[0030] As the working electrode side current collector 131, for example, a carbonaceous material or a metallic material can be used. As the carbonaceous material constituting the working electrode side current collector 131, for example, carbon paper, carbon cloth, nonwoven carbon mat, porous gas diffusion layer (GDL), etc. can be used. As the metallic material constituting the working electrode side current collector 131, for example, a mesh structure of metals such as Al, Ni, and SUS can be used.

[0031] The working electrode film 132 adsorbs and desorbs carbon dioxide from a carbon dioxide-containing gas through an electrochemical reaction. The working electrode film 132 comprises a carbon dioxide adsorbent, a working electrode conductive additive, and a working electrode binder. The working electrode binder will be described in detail later.

[0032] Carbon dioxide adsorbents are electroactive species (i.e., active materials) that adsorb carbon dioxide by accepting electrons and desorb the adsorbed carbon dioxide by releasing electrons. Examples of carbon dioxide adsorbents include carbon materials, metal oxides, and polyanthraquinones.

[0033] The working electrode side conductive additive is a conductive substance that forms a conductive path to the carbon dioxide adsorbent. Examples of carbon materials that can be used as the working electrode side conductive additive include carbon nanotubes, carbon black, and graphene.

[0034] The counter electrode 140 has a counter electrode side current collector 141 and a counter electrode side electrode film 142. The counter electrode side current collector 141 is a conductive member connected to the control power supply 120. The counter electrode side current collector 141 may be made of the same material as the working electrode side current collector 131, or it may be made of a different material.

[0035] The counter electrode film 142 exchanges electrons with the working electrode film 132. The counter electrode film comprises a counter active material, a counter conductive additive, and a counter binder. The counter binder will be described in detail later.

[0036] The counter-electrode active material is an auxiliary electroactive species that exchanges electrons with the carbon dioxide adsorbent. The counter-electrode active material is a substance that can exchange electrons through changes in the valence state of the metal or through the movement of charge into and out of the π electron cloud.

[0037] As the counter-electrode active material, for example, a metal complex that enables electron transfer by changing the valence of a metal ion can be used. Examples of such metal complexes include cyclopentadienyl metal complexes such as ferrocene, nickerosene, and cobaltocene, or porphyrin metal complexes.

[0038] In this embodiment, a compound having a ferrocene skeleton is used as the counter electrode active material. Specifically, PVFc (polyvinylferrocene), which is polymerized ferrocene, is used as the counter electrode active material.

[0039] The counter electrode conductive additive is a conductive material that forms a conductive path to the counter electrode active material. The counter electrode conductive additive is used in mixture with the counter electrode active material. The counter electrode conductive additive may be made of the same material as the working electrode conductive additive, or it may be made of a different material. The counter electrode conductive additive is, for example, in particulate form.

[0040] The separator 150 is placed between the working electrode film 132 and the counter electrode film 142. The separator 150 separates the working electrode film 132 and the counter electrode film 142. In other words, the separator 150 prevents physical contact between the working electrode film 132 and the counter electrode film 142. The separator 150 also suppresses electrical short circuits between the working electrode film 132 and the counter electrode film 142.

[0041] As the separator 150, a separator made of a cellulose membrane, a polymer, a composite material of a polymer and ceramic, etc., can be used. A porous separator may also be used as the separator 150.

[0042] An ion-conducting member is provided between the working electrode film 132 and the separator 150, and between the counter electrode film 142 and the separator 150. The ion-conducting member promotes conductivity to the carbon dioxide adsorbent. In this embodiment, an electrolyte is provided as the ion-conducting member. More specifically, an ionic liquid is used as the electrolyte. An ionic liquid is a salt of a liquid that is non-volatile at room temperature and atmospheric pressure.

[0043] Here, the working electrode binder and the counter electrode binder in this embodiment will be described. The working electrode binder and the counter electrode binder are holding materials that have adhesive properties.

[0044] The working electrode binder holds the carbon dioxide adsorbent and the working electrode conductive additive to the working electrode current collector 131. Specifically, a mixture of the carbon dioxide adsorbent, the working electrode conductive additive, and the working electrode binder is formed, and this mixture is adhered to the working electrode current collector 131. The carbon dioxide adsorbent and the working electrode conductive additive are held inside the working electrode binder.

[0045] The working electrode binder contains a polymer resin. The polymer resin is composed of carbon and halogen elements, or carbon, halogen elements, and oxygen. In other words, the working electrode binder contains a polymer resin that does not contain hydrogen (H).

[0046] Figure 4 illustrates the polymer resin contained in the working electrode binder of this embodiment. The polymer resin includes at least one of the following: PTFE (polytetrafluoroethylene), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), PCTFE (polychlorotrifluoroethylene), and PFA (perfluoroalkoxyalkane).

[0047] The counter electrode binder is a material that can hold the counter electrode active material and the counter electrode conductive additive to the counter electrode current collector 141 and is also conductive. The counter electrode binder may be made of the same material as the working electrode binder, or a different material may be used. In this embodiment, PVDF is used as the counter electrode binder.

[0048] Next, the working electrode formation process for forming the working electrode 130 of the electrochemical cell 101 in this embodiment will be described.

[0049] In the working electrode formation process, first, a working electrode mixing process is performed in which the working electrode constituent materials, which constitute the working electrode side electrode film 132, are mixed. The working electrode constituent materials include a carbon dioxide adsorbent, a working electrode side conductive additive, and a working electrode side binder. In this embodiment, a metal oxide is used as the carbon dioxide adsorbent, a carbon material is used as the working electrode side conductive additive, and PTFE, a polymer resin, is used as the working electrode side binder.

[0050] In the working electrode side mixing step of this embodiment, the working electrode constituent materials are dispersed and mixed using a homogenizer or the like, and then dissolved in a solvent (i.e., an organic solvent) to produce a mixture. At this time, the PTFE, which is the working electrode side binder, is dispersed and mixed as nanoparticles with an equivalent circular diameter of 1 μm or less. In this embodiment, NMP (N-methylpyrrolidone) is used as the solvent.

[0051] Next, a heating step is performed in which the mixed working electrode constituent material is heated to the thermal decomposition temperature of PTFE. In the heating step of this embodiment, the mixed working electrode constituent material is applied to the working electrode side current collector 131 and then fired at 350°C. As a result, a working electrode side electrode film 132 is formed on the surface of the working electrode side current collector 131. Thus, the working electrode formation step is completed.

[0052] Here, the inventors investigated the amount of decomposition products relative to the amount of carbon dioxide adsorbed in carbon dioxide recovery using an electrochemical cell 101 containing the working electrode 130 obtained in the working electrode formation step described above. Specifically, the combination of recovery mode and release mode was considered as one cycle, and the amount of decomposition products relative to the amount of carbon dioxide adsorbed was measured in each cycle.

[0053] The ratio of decomposition products to carbon dioxide adsorbed is the amount of decomposition products recovered relative to the amount of carbon dioxide adsorbed after one cycle of operation. Decomposition products are substances produced when the working electrode 130 and counter electrode 140 are decomposed. The smaller the ratio of decomposition products to carbon dioxide adsorbed, the less likely the working electrode 130 and counter electrode 140 of the electrochemical cell 101 are to decompose.

[0054] In addition, as Comparative Example 1, an electrochemical cell 101 was prepared using PVDF for both the working electrode binder and the counter electrode binder. The results are shown in Figure 5.

[0055] As shown in Figure 5, when using the electrochemical cell 101 of this embodiment, the amount of decomposition products relative to the carbon dioxide adsorbed amount can be reduced by an average of approximately 27% compared to Comparative Example 1. Therefore, by using PTFE as the working electrode binder of the working electrode side electrode film 132, the working electrode 130 of the electrochemical cell 101 becomes less susceptible to decomposition.

[0056] On the other hand, in Comparative Example 1, PVDF is used for both the working electrode binder and the counter electrode binder, but the bond energy of the CH bond in PVDF is lower than the bond energy of the CF bond in PTFE. Therefore, as shown in Figure 6, the PVDF reacts with oxygen in the atmosphere, and the F and H elements contained in the PVDF are desorbed as hydrogen fluoride. As a result, the working electrode binder and the counter electrode binder decompose, making the working electrode 130 and counter electrode 140 of the electrochemical cell 101 more susceptible to decomposition.

[0057] Furthermore, the inventors investigated the surface state and structure of the working electrode side electrode film 132 obtained in the working electrode formation step described above. In this embodiment, in the working electrode side mixing step, PTFE, which is the working electrode side binder, is dispersed and mixed as nanoparticles with a circular equivalent diameter of 1 μm or less.

[0058] In this embodiment, as shown in Figure 7, the working electrode side electrode film 132 covered the entire surface of the working electrode side current collector 131, and no exposure of the working electrode side current collector 131 was observed. Furthermore, as shown in Figure 8, the working electrode side electrode film 132 had a uniformly formed film structure.

[0059] In contrast, as Comparative Example 2, the surface state and structure of a working electrode electrode film was investigated in which PTFE, the working electrode binder, was dispersed and mixed as particles with an equivalent circular diameter of 5 μm during the working electrode side mixing process.

[0060] In Comparative Example 2, as shown in Figure 9, there were areas where the working electrode side current collector 131 was exposed through gaps in the working electrode side electrode film 132, confirming that the working electrode side electrode film 132 did not completely cover the surface of the working electrode side current collector 131. Furthermore, as shown in Figure 10, coarse PTFE particles 300 were present in the working electrode side electrode film 132, indicating that the film structure was not uniformly formed.

[0061] As described above, in the electrochemical cell 101 of this embodiment, the polymer resin contained in the working electrode binder of the working electrode electrode film 132 is composed of carbon and halogen elements, or carbon, halogen elements and oxygen. This suppresses the decomposition of the working electrode binder by components contained in the atmosphere. Therefore, it is possible to ensure the movement of electrons between the working electrode current collector 131, the carbon dioxide adsorbent, and the working electrode conductive additive. In addition, the carbon dioxide adsorbent becomes less likely to peel off from the working electrode current collector 131, and the decrease in the amount of adsorption of the electrochemical cell 101 over time can be suppressed. As a result, it is possible to improve the electrode performance of the electrochemical cell 101.

[0062] Specifically, in this embodiment, PTFE is used as the working electrode binder. The CF bonds in PTFE are strong and resistant to oxidation. Therefore, the decomposition of the PTFE working electrode binder by oxygen in the atmosphere can be suppressed.

[0063] Incidentally, in the electrochemical cell 101 of this embodiment, an ionic liquid is provided as an electrolyte between the working electrode side electrode film 132 and the separator 150, and between the counter electrode side electrode film 142 and the separator 150. According to the inventors' investigations, it became clear that when PVDF is used as the working electrode side binder, the PVDF swells when a voltage is applied. Furthermore, it was found that repeated application of voltage to the electrochemical cell 101 causes repeated swelling and contraction of the PVDF, which may reduce the durability and conductivity of the working electrode side electrode film 132.

[0064] In contrast, the PTFE used as the working electrode binder in this embodiment is less prone to swelling when a voltage is applied, even when an ionic liquid is provided as the electrolyte. This suppresses a decrease in the durability and conductivity of the working electrode film 132.

[0065] Incidentally, since PTFE has almost no solubility in solvents, using PTFE as a binder on the working electrode side may reduce the binding properties of the working electrode side electrode film 132.

[0066] In contrast, in the working electrode formation process of this embodiment, PTFE, which is the working electrode binder, is dispersed and mixed as nanoparticles with an equivalent circular diameter of 1 μm or less, and then the working electrode side electrode film 132 is formed. By making the average equivalent circular diameter of the polymer resin of the working electrode side binder 1 μm or less in this way, it is possible to significantly improve the binding properties of the working electrode side electrode film 132.

[0067] (Second Embodiment) Next, a second embodiment of this disclosure will be described. This second embodiment differs from the first embodiment in the configuration and manufacturing method of the counter electrode 140.

[0068] In the electrochemical cell 101 of this embodiment, the counter electrode binder of the counter electrode film 142 contains the same polymer resin as the working electrode binder. That is, the polymer resin contained in the counter electrode binder is composed of carbon and halogen elements, or carbon, halogen elements and oxygen. In other words, the counter electrode binder contains a polymer resin that does not contain hydrogen. This polymer resin contains at least one of PTFE, FEP, PCTFE, or PFA.

[0069] Next, the counter electrode formation process for forming the counter electrode 140 of the electrochemical cell 101 in this embodiment will be described.

[0070] In the counter electrode formation process, first, a counter electrode mixing process is performed in which the counter electrode constituent materials, which constitute the counter electrode film 142, are mixed. The counter electrode constituent materials include a counter electrode active material, a counter electrode conductive additive, and a counter electrode binder. In this embodiment, PVFc is used as the counter electrode active material, carbon black is used as the counter electrode conductive additive, and PTFE, a polymer resin, is used as the counter electrode binder.

[0071] In the counter electrode mixing step of this embodiment, the counter electrode constituent materials are dispersed and mixed using a homogenizer or the like, and then dissolved in a solvent to produce a mixture. At this time, the PTFE, which is the counter electrode binder, is dispersed and mixed as nanoparticles with an equivalent circular diameter of 1 μm or less. In this embodiment, NMP (N-methylpyrrolidone) is used as the solvent.

[0072] Next, a compression step is performed to compress the mixed counter electrode constituent material. In the compression step of this embodiment, the mixed counter electrode constituent material is pressed onto the counter electrode current collector 141 by press molding. As a result, a counter electrode film 142 is formed on the surface of the counter electrode current collector 141. Thus, the counter electrode formation step is completed.

[0073] As described above, in the electrochemical cell 101 of this embodiment, the polymer resin contained in the counter electrode binder of the counter electrode film 142 is composed of carbon and halogen elements, or carbon, halogen elements and oxygen. This suppresses the decomposition of the counter electrode binder by components contained in the atmosphere. As a result, it is possible to improve the electrode performance of the electrochemical cell 101.

[0074] By the way, in the electrochemical cell 101 of this embodiment, PVFc is used as the counter electrode active material among the counter electrode constituent materials. Since PVFc is flammable, high-temperature firing cannot be performed in the counter electrode formation process.

[0075] In contrast, the counter electrode formation process of this embodiment includes a compression step in which the mixed counter electrode constituent material is pressed onto the counter electrode side current collector 141. This makes it possible to form a counter electrode side electrode film 142 on the surface of the counter electrode side current collector 141 without performing high-temperature firing.

[0076] (Other embodiments) This disclosure is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit of this disclosure. Furthermore, the means disclosed in each of the embodiments described above may be combined as appropriate to the extent that they are feasible.

[0077] (1) For example, in the embodiments described above, examples were given in which both the working electrode binder and the counter electrode binder, or the working electrode binder alone, are composed of carbon and halogen elements, or of carbon, halogen elements and oxygen, but the invention is not limited to these embodiments. For example, the counter electrode binder alone may be composed of carbon and halogen elements, or of carbon, halogen elements and oxygen.

[0078] (2) In the embodiments described above, an example in which PTFE was used as the working electrode binder or the counter electrode binder was explained, but the invention is not limited to this embodiment. For example, a substance containing a polymer resin other than PTFE, such as a copolymer of PTFE and PVDF, may be used as the working electrode binder or the counter electrode binder. This makes it possible to achieve both film-forming properties and durability in the electrode films 132 and 142. [Explanation of symbols]

[0079] 130 Working electrode 132 Working electrode side electrode film (electrode film) 140 opposite poles 142 Counter electrode film (electrode film)

Claims

1. A working electrode (130) that performs adsorption and desorption of the gas to be recovered from a mixed gas containing the gas to be recovered by an electrochemical reaction, It comprises a counter electrode (140) that exchanges electrons with the working electrode, The gas to be recovered is carbon dioxide. The aforementioned mixed gas is the atmosphere. The electrode films (132, 142) constituting at least one of the working electrode and the counter electrode have an active material, a conductive additive and a binder. The binder has the function of holding the active material and the conductive additive in the current collector (131, 141), and also contains a polymer resin. In order to suppress the decomposition of the binder by components contained in the atmosphere, the polymer resin is composed of carbon and halogen elements, or carbon, halogen elements and oxygen. The aforementioned polymer resin contains at least one of FEP, PCTFE, or PFA. An electrochemical cell having an average circular equivalent diameter of 1 μm or less for the polymer resin.

2. A working electrode (130) that performs adsorption and desorption of the gas to be recovered from a mixed gas containing the gas to be recovered by an electrochemical reaction, It comprises a counter electrode (140) that exchanges electrons with the working electrode, The gas to be recovered is carbon dioxide. The aforementioned mixed gas is the atmosphere. The working electrode material constituting the electrode film (132) of the working electrode includes a polymer resin as a binder. In order to suppress the decomposition of the binder by components contained in the atmosphere, the polymer resin is composed of carbon and halogen elements, or carbon, halogen elements and oxygen. The polymer resin is a method for producing an electrochemical cell containing at least one of FEP, PCTFE, and PFA, The process includes a working electrode forming step for forming the working electrode, The aforementioned working electrode formation step is, A mixing step of mixing the working electrode constituent materials, The process includes a heating step of heating the working electrode constituent material mixed in the mixing step to the thermal decomposition temperature of the polymer resin, A method for producing an electrochemical cell, wherein the mixing step involves dispersing and mixing the polymer resin as nanoparticles with an average circular diameter of 1 μm or less.

3. The method for manufacturing an electrochemical cell according to claim 2, wherein the working electrode constituent material comprises an adsorbent for adsorbing the gas to be recovered, a working electrode side conductive additive, and the polymer resin.

4. A working electrode (130) that performs adsorption and desorption of the gas to be recovered from a mixed gas containing the gas to be recovered by an electrochemical reaction, It comprises a counter electrode (140) that exchanges electrons with the working electrode, The gas to be recovered is carbon dioxide. The aforementioned mixed gas is the atmosphere. The counter electrode material constituting the counter electrode electrode film (142) includes polyvinylferrocene as the counter electrode-side active material that exchanges electrons with the working electrode, and a polymer resin as a binder. In order to suppress the decomposition of the binder by components contained in the atmosphere, the polymer resin is composed of carbon and halogen elements, or carbon, halogen elements and oxygen. The polymer resin is a method for producing an electrochemical cell containing at least one of FEP, PCTFE, and PFA, The process includes a counter electrode forming step for forming the counter electrode, The aforementioned counter electrode formation step is, A mixing step of mixing the counter electrode constituent materials, The process includes a compression step in which the counter electrode constituent material mixed in the mixing step is compressed without a heating step, A method for producing an electrochemical cell, wherein the mixing step involves dispersing and mixing the polymer resin as nanoparticles with an average circular diameter of 1 μm or less.

5. The method for manufacturing an electrochemical cell according to claim 4, wherein the counter electrode constituent material comprises the counter electrode side active material, the counter electrode side conductive additive, and the polymer resin.

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