Method for manufacturing electrochemical cell, and electrochemical cell

Abstract

To provide an electrochemical cell having improved gas adsorption speed, and a method for manufacturing the same.SOLUTION: A gas adsorption system has a first electrode film for adsorbing predetermined gas. The first electrode film has a gas adsorption material 133 and an action electrode side binder 135, and a gap part 136 having a diameter equal to or more than an average free path of gas. A step of forming the first electrode film includes: coating a paste containing the gas adsorption material 133, the action electrode side binder 135, a paste solvent 137 and a pore-forming material 138 of inorganic salt into a sheet shape and forming a sheet body; and drying the sheet body and removing the paste solvent 137. The step includes: coating an extraction solvent onto the sheet body after drying; extracting the pore-forming material 138; and forming the gap part 136.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing an electrochemical cell used in a gas adsorption system for adsorbing a predetermined gas, and the electrochemical cell. [Background technology]

[0002] Patent Document 1 has proposed an electrochemical cell for use in a gas adsorption system capable of adsorbing and desorbing a specific gas, such as carbon dioxide (CO2). The electrochemical cell described in Patent Document 1 includes a working electrode containing a CO2 adsorbent, a counter electrode, an insulating layer disposed between the working electrode and the counter electrode, and an electrolyte material covering the working electrode, the counter electrode, and the insulating layer. This electrochemical cell can control the adsorption and desorption of CO2 in the CO2 adsorbent in the working electrode by turning an electric field on and off, making it possible to recover CO2 from a CO2-containing gas. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-177883 Summary of the Invention [Problem to be solved by the invention]

[0004] This type of electrochemical cell is required to further improve the gas adsorption rate. The electrochemical cell described in Patent Document 1 improves the CO2 gas adsorption rate by adsorbing CO2 using the Coulomb force of electrons, rather than by chemically bonding a specific element with CO2, but there is still room for improvement.

[0005] In the conventional electrochemical cell described above, the entire cell is immersed in an electrolyte solution, and the electrode film of the working electrode has almost no gaps. As a result of extensive research by the present inventors, they have newly discovered that the gas adsorption rate can be improved by forming a plurality of voids of a predetermined size or larger in the electrode film of the working electrode.

[0006] In view of the above, an object of the present disclosure is to provide an electrochemical cell with an improved gas adsorption rate and a method for manufacturing the same. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, a method for manufacturing an electrochemical cell includes: A method for manufacturing an electrochemical cell (110) including a working electrode (130) having an electrode film (132) that adsorbs a predetermined gas, a counter electrode (140), and a separator (150) disposed between the working electrode and the counter electrode, comprising: forming a sheet body by applying a paste containing a gas adsorbent (133) for adsorbing gas, a paste solvent (137), and a pore-forming material (138) composed of an inorganic salt and having a particle size equal to or smaller than the thickness of the electrode film; drying the sheet body to remove the paste solvent; and applying an extraction solvent to the dried sheet to extract the pore-forming material from the sheet, thereby forming an electrode film having voids (136).

[0008] This results in a method for manufacturing an electrochemical cell that includes applying a paste containing a gas adsorbent, a paste solvent, and a pore-forming material to form a sheet body, drying the sheet body to remove the paste solvent, and then extracting the pore-forming material with an extraction solvent to form voids.The voids function as gas-phase passages for the gas, resulting in an electrode film that improves the speed at which the gas reaches the gas adsorbent at the working electrode compared to a structure without voids, making it possible to manufacture an electrochemical cell that improves the adsorption speed of the gas to be adsorbed.

[0009] According to one aspect of the disclosure, an electrochemical cell comprises: a working electrode (130) having an electrode film (132) that adsorbs a predetermined gas; a counter electrode (140) that pairs with the working electrode; a separator (150) disposed between the working electrode and the counter electrode; The electrode film has a plurality of voids (136) therein, each having a diameter equal to or greater than the mean free path of a predetermined gas.

[0010] This electrochemical cell has a structure in which the electrode film of the working electrode that absorbs gas is formed with a plurality of voids with a diameter equal to or greater than the mean free path of the gas, and the voids function as gas-phase passages for the gas. Therefore, compared to a structure without voids, the electrode film has an improved rate at which the gas reaches the gas adsorbent at the working electrode, resulting in an electrochemical cell with an improved gas adsorption rate.

[0011] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing a gas adsorption system according to a first embodiment. [Figure 2] FIG. 2 is a diagram corresponding to an enlarged view of region II in FIG. 1, and is an explanatory diagram of CO 2 adsorption at the working electrode. [Figure 3] FIG. 3 is a diagram corresponding to FIG. 2 and is an explanatory diagram of CO2 adsorption in a gas adsorption system of a comparative example. [Figure 4] FIG. 10 is a diagram showing the results of observing a cross section of a first electrode film in a comparative example with a scanning electron microscope (SEM). [Figure 5] FIG. 3 is a diagram showing the results of SEM observation of a cross section of a first electrode film in an example. [Figure 6] FIG. 1 is a diagram showing the results of comparing the CO2 adsorption rates of Examples and Comparative Examples. [Figure 7] 5A to 5C are diagrams illustrating a manufacturing process of the first electrode film. [Figure 8] FIG. 3 is a cross-sectional view corresponding to FIG. 2, showing the configuration of a first electrode according to a second embodiment. [Figure 9] 10A to 10C are diagrams illustrating a manufacturing process of the first electrode film according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the following embodiments, identical or equivalent parts will be denoted by the same reference numerals.

[0014] (First embodiment) The following description will be given with reference to a gas adsorption system 100 according to a first embodiment. The gas adsorption system 100 recovers a gas to be recovered from a mixed gas containing the gas to be recovered by an electrochemical reaction. The gas to be recovered is, for example, an acidic gas such as CO2, NOx, or SOx. Examples of the mixed gas include the atmosphere and exhaust gas from an internal combustion engine. In this specification, a case where CO2 is recovered from a mixed gas will be described as a representative example.

[0015] [Basic configuration] 1, the gas adsorption system 100 includes an electrochemical cell 110 and a control power supply 120, and is an electrosorption / desorption system in which gas adsorption and desorption occur through an electrochemical reaction in the electrochemical cell 110. The electrochemical cell 110 includes, for example, a plate-shaped first electrode 130, a second electrode 140, and a separator 150, with the separator 150 disposed between the first electrode 130 and the second electrode 140. The control power supply 120 is a power supply device for the gas adsorption system 100, and is controlled, for example, by a control device (not shown), and is used to switch between a gas adsorption mode and a gas desorption mode in the electrochemical cell 110.

[0016] The electrochemical cell 110 is immersed in an electrolyte (not shown), such as an ionic liquid. Examples of the ionic liquid that can be used include 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([EMIM][TfN]), 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([BMIM][TfN]), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF]), 1-ethyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide, N,N,N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium tetrafluoroborate, and 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide.

[0017] The first electrode 130 is, for example, a negative electrode. The first electrode 130 includes a first current collector 131 and a first electrode film 132, as shown in FIG.

[0018] The first current collector 131 is made of a conductive material that allows gas to pass through, and is connected to the control power supply 120. The first current collector 131 is made of any conductive material, such as a carbonaceous material such as carbon paper, carbon cloth, nonwoven carbon mat, or porous gas diffusion layer (GDL), or a metal material such as Al, Ni, Ti, or SUS, and has a porous or mesh structure. GDL is an abbreviation for Gas Diffusion Layer.

[0019] The first electrode film 132 is a working electrode that adsorbs and desorbs a predetermined gas from a mixed gas containing the gas through an electrochemical reaction. The first electrode film 132 has a gas adsorbent 133, a working electrode-side conductive additive 134, and a working electrode-side binder 135, and has a plurality of voids 136 formed in the film. In other words, the first electrode film 132 is not configured so that all of the gaps between the gas adsorbent 133, the working electrode-side conductive additive 134, and the working electrode-side binder 135 are filled with an electrolyte material, and has voids 136 that serve as gas-phase passages for the gas to be adsorbed.

[0020] The gas adsorbent 133 is, for example, a CO2 adsorbent that adsorbs and desorbs CO2. For example, when an electric field is applied by the control power supply 120, the gas adsorbent 133 adsorbs CO2 by receiving electrons via the first current collector 131, and desorbs the adsorbed CO2 by releasing electrons. When the gas adsorbent 133 is used as a CO2 adsorbent, for example, an organic compound such as polyanthraquinone, carbon, or a metal oxide can be used.

[0021] The working electrode-side conductive additive 134 is a conductive substance that forms a conductive path to the gas adsorbent 133. As the working electrode-side conductive additive 134, for example, a carbon material such as carbon nanotubes, carbon black, or graphene, or metal fine particles, a conductive polymer, or the like can be used.

[0022] The working electrode side binder 135 is a retaining material that retains the gas adsorbent 133 and the working electrode side conductive assistant 134 on the first current collector 131. The working electrode side binder 135 is made of, for example, a polymer material such as epoxy resin, polyimide, or a fluororesin such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF). Note that the working electrode side binder 135 may be configured to include, in addition to the above-mentioned polymer material, a conductive filler made of a conductive material such as Ag.

[0023] The voids 136 are spaces formed in the first electrode film 132 and serve as gas-phase passages for the gas to be adsorbed by the gas adsorbent 133. The voids 136 are formed by extracting a pore-forming material 138 used in the manufacturing process of the first electrode film 132 (described later), and have a diameter less than the film thickness of the first electrode film 132. The diameter of the voids 136 is greater than or equal to the mean free path to facilitate the entry of the gas to be adsorbed. The mean free path is the average distance traveled between the first and second collisions of gas molecules as they collide with one another, and is determined by the density, temperature, and pressure of the gas molecules. For example, the mean free path for CO2 is approximately 44 nm at 25°C and 1 atmosphere. The diameter of the voids 136 can be adjusted appropriately depending on the operating environment (e.g., temperature and pressure) of the electrochemical cell 110 and the type of gas to be adsorbed. The process of forming the voids 136 will be described later, but the diameter and number of the voids 136 can be designed as appropriate depending on the size and amount of the pore-forming material 138. Some of the multiple voids 136 are in communication with a surface of the first electrode film 132 other than the surface that contacts the separator 150, for example, the surface on the first current collector 131 side shown in FIG. 2 or a side surface adjacent to that surface. Note that, in FIG. 2, multiple independent voids 136 are shown to make the configuration of the voids 136 easier to understand, but the present invention is not limited to this configuration, and some of the voids 136 may be connected to each other. The same applies to FIG. 8 described later.

[0024] The second electrode 140 is, for example, a positive electrode, and includes a second current collector 141 and a second electrode film 142. The second current collector 141 is a conductive member connected to the control power supply 120. The second current collector 141 may be made of the same material as the first current collector 131, or may be made of a different material.

[0025] The second electrode film 142 is a counter electrode that exchanges electrons with the first electrode film 132. The second electrode film 142 is, for example, configured by mixing multiple materials, similar to the first electrode film 132, and has a counter electrode-side active material, a counter electrode-side conductive additive, and a counter electrode-side binder, which are not shown.

[0026] The counter electrode active material is an electroactive species that exchanges electrons with the gas adsorbent 133 of the first electrode film 132. Examples of the counter electrode active material include metal complexes that change the valence of metal ions, such as cyclopentadienyl metal complexes (e.g., ferrocene, nickelocene, or cobaltocene), or porphyrin metal complexes, allowing electron exchange. Examples of the counter electrode active material include transition metal oxides (e.g., Ru, Mn, Fe, or Mo) that change the valence of transition metals, allowing electron exchange. The counter electrode conductive additive is a conductive material that forms a conductive path to the counter electrode active material. For example, the same conductive material as the working electrode conductive additive 134 may be used, or a different conductive material may be used. The counter electrode binder is composed of a material that can hold the counter electrode active material and the counter electrode conductive additive on the second current collector 141. The counter electrode side binder may be made of, for example, the same material as the working electrode side binder 135, or may be made of a different material.

[0027] The separator 150 is disposed between the first electrode film 132 and the second electrode film 142, and is a member that prevents physical contact between the first electrode film 132 and the second electrode film 142. The separator 150 suppresses electrical short circuits between the first electrode film 132 and the second electrode film 142. The separator 150 can be made of an insulating material such as a cellulose film, a polymer, a composite material of a polymer and ceramic, or a porous body.

[0028] The basic configuration of the gas adsorption system 100 has been described above.

[0029] [Gas adsorption and desorption steps] In the gas adsorption system 100, the control power supply 120 controls the potential applied between the first electrode 130 and the second electrode 140, thereby performing, for example, a CO 2 adsorption process and a desorption process.

[0030] For example, in the adsorption process, an adsorption potential is applied between the first electrode 130 and the second electrode 140 of the electrochemical cell 110 from the control power supply 120. At this time, in the gas adsorption system 100, the counter electrode active material of the second electrode film 142 simultaneously donates electrons and the first electrode film 132 supplies electrons to the gas adsorbent 133. When an adsorption potential is applied between the first electrode film 132 and the second electrode film 142, the counter electrode active material of the second electrode film 142 releases electrons and supplies them to the first electrode film 132. The gas adsorbent 133 then receives electrons, increasing its bonding strength with CO2 and adsorbing CO2 contained in the mixed gas supplied to the electrochemical cell 110. This allows the electrochemical cell 110 to capture CO2 from the mixed gas. The mixed gas from which CO2 has been captured by the gas adsorption system 100, i.e., the CO2-removed gas, is released into the atmosphere, for example, through a gas flow path (not shown).

[0031] Furthermore, for example, in the desorption process, a desorption potential is applied between the first electrode 130 and the second electrode 140 of the electrochemical cell 110 from the control power supply 120. At this time, in the gas adsorption system 100, the applied voltage causes the gas adsorbent 133 of the first electrode film 132 to donate electrons and the second electrode film 142 to supply electrons to the counter electrode active material. When this desorption potential is applied, the gas adsorbent 133 releases electrons, and the bonding strength with CO2 decreases, causing the gas adsorbent 133 to desorb and release CO2. The electrons released by the gas adsorbent 133 are supplied to the counter electrode active material of the second electrode film 142. Then, the CO2 gas released by the gas adsorbent 133 of the gas adsorption system 100 is sent to a CO2 utilization device (not shown), for example, through a gas flow path (not shown). Examples of the CO2 utilization device include a storage tank for storing CO2 and a conversion device for converting CO2 into fuel. The gas adsorption system 100 repeatedly executes the cycle of the gas adsorption process and desorption process described above.

[0032] [Improvement of gas adsorption speed] Next, the improvement in the gas adsorption rate in the gas adsorption system 100 of this embodiment will be described in comparison with the structure of a gas adsorption system of a comparative example shown in FIG.

[0033] The gas adsorption system of the comparative example differs from the gas adsorption system 100 in the structure of the first electrode 200. As shown in Fig. 3, the first electrode 200 has a first current collector 131 and a first electrode film 210 made of a gas adsorbent 133, a working electrode-side conductive additive 134, and a working electrode-side binder 135. When the cross section of the first electrode 200 was observed with a scanning electron microscope, as shown in Fig. 4, almost no black portions, i.e., void portions, were observed, and the proportion of voids in the first electrode film 210 was 2 to 6%, with almost no gaps larger than the mean free path of gas.

[0034] Here, in gas diffusion, interactions with the wall surface become dominant in gaps smaller than the mean free path of the gas, significantly reducing the diffusion rate of the gas. Therefore, in order to increase the diffusion rate of the gas in the first electrode film and improve the gas adsorption / desorption rate, it is effective to form voids larger than the mean free path of the gas in the first electrode film. As a result of extensive research by the inventors, they have devised an electrochemical cell 110, as shown in FIG. 2, in which a plurality of voids 136 with a diameter equal to or larger than the mean free path are formed in the first electrode film 132, serving as gas-phase paths through which CO2 gas can diffuse in a gaseous state.

[0035] In the electrochemical cell 110 of this embodiment, a plurality of voids 136 having a diameter equal to or greater than the mean free path of the gas to be adsorbed are formed in the first electrode film 132. Therefore, the first electrode film 132 has a structure that improves the speed at which CO2 gas diffuses through the voids 136 and reaches the gas adsorbent 133. When the cross section of the first electrode film 132 was observed with a scanning electron microscope (SEM), as shown in FIG. 5, many black portions, i.e., void portions, were observed, and the proportion of voids in the first electrode film 132 was approximately 60%, with many gaps equal to or greater than the mean free path of the gas. Therefore, in the gas adsorption system 100, the diffusion rate of CO2 gas in the first electrode film 132 is significantly higher than in the comparative example, and therefore the adsorption rate of CO2 gas is improved.

[0036] The CO2 gas adsorption rate was measured under the same conditions for the gas adsorption system of the comparative example and the gas adsorption system 100 of the example, and the results shown in Figure 6 were obtained. The CO2 gas adsorption rate of the gas adsorption system 100 was approximately 1.6, with the CO2 gas adsorption rate of the gas adsorption system of the comparative example being set to 1. The gas adsorption rate can be obtained, for example, by flowing a constant concentration of CO2 gas through the gas adsorption system and calculating the rate based on the CO2 concentration after the adsorption process, or by filling the gas adsorption system with a constant amount of CO2 gas and calculating the rate based on the CO2 concentration after the adsorption process.

[0037] [Step of forming first electrode film] Next, the process of forming the first electrode film 132 of the electrochemical cell 110 will be described with reference to FIG.

[0038] First, a first kneading step is performed in which a polymer material (working electrode side binder 135), a gas adsorbent 133, a working electrode side conductive additive 134, and a paste solvent 137 are mixed. For example, a solvent capable of dissolving the working electrode side binder 135 is used. Examples of the paste solvent 137 that can be used include protonophilic solvents such as dimethylformamide, dimethyl sulfoxide, 1-methyl-2-pyrrolidone, tetrahydrofuran, pyridine, and hexamethylphosphoramide. Examples of the paste solvent 137 that can be used include protonophilic solvents such as acetonitrile, propylene carbonate, ethylbenzene, cyclohexanone, cyclohexane, p-cymene, benzyl benzoate, butyl benzoate, dimethylcyclohexane, xylene, toluene, and methylcyclohexane. The paste solvent 137 is not limited to the above, and other protonophilic, protonphobic, and amphoteric solvents may also be used. The paste obtained in the first kneading step is in a state where a gas adsorbent 133, a working electrode side conductive assistant 134, a working electrode side binder 135, and a paste solvent 137 are mixed together, as shown in FIG.

[0039] It is preferable that the paste solvent 137 does not dissolve the inorganic salt pore-forming material 138 used in the next step, but if a solvent that dissolves inorganic salts is used, it is sufficient to prepare a solvent that is saturated with inorganic salts in advance. This makes it possible to prevent the inorganic salts from being unintentionally extracted before the extraction step described below in which the inorganic salts are extracted.

[0040] Subsequently, a second kneading step is performed in which an inorganic salt pore-forming material 138 is mixed with the paste obtained in the first kneading step. The second kneading step results in the paste having the pore-forming material 138 dispersed as particles within it. The inorganic salt may be, for example, a combination of a metal cation and an inorganic anion. This allows for both stability with respect to the paste solvent 137 and high solubility in water when water is used as the extraction solvent in the extraction step described below, making it possible to stably form voids 136.

[0041] As a metal cation, for example, Li, which has a high ionization tendency, + , K. + , Ba 2+ , Ca 2+ , Na + , Mg 2+ , Al 3+ , Mn 2+ Inorganic salts, instead of metal cations, are effective. + Examples of inorganic anions include Cl. - , Br - , I - Halide ions such as HCO3 - , CO3 2- , NO3 - , SO4 2- , BO3 3-Acid ions such as the above are effective. Ion species with different valences or hydrated species can be used in the same way. It is preferable that the ion species does not reduce the amount of gas adsorption even if it remains. The particle size and amount of inorganic salt to be kneaded affect the diameter of the voids 136 to be formed later and the porosity of the first electrode film 132, so they are appropriately changed depending on the design. The inorganic salt used should have a particle size at least smaller than the thickness of the paste to be applied in the subsequent application process. Furthermore, the inorganic salt used should have a melting point or thermal decomposition temperature at least higher than the drying temperature in the drying process of the paste solvent 137.

[0042] Next, a coating process is performed in which the paste obtained in the second kneading process is coated into a sheet using a coating method such as screen printing, metal mask printing, or a printing method using a doctor blade, applicator, wire bar, gravure, or slot die. Hereinafter, for convenience of explanation, the sheet-like paste obtained in this coating process will be referred to as a "sheet body." Between the second kneading process and the subsequent drying process, it is preferable to maintain a relatively low temperature to prevent an increase in the solubility of the pore-forming material 138 in the paste solvent. This prevents the pore-forming material 138 from dissolving before the extraction process, resulting in a first electrode film 132 having voids 136 with the designed diameter. If the pore-forming material 138 is barely soluble in the paste solvent, temperature control between the second kneading process and the drying process is unnecessary and is not particularly limited.

[0043] The sheet is then dried in a drying step to evaporate the paste solvent. For example, if the pore-forming material 138 dissolves significantly in the paste solvent, a non-heating method, such as vacuum drying or air drying, that can lower the process temperature is preferred in order to prevent dissolution of the pore-forming material 138. Alternatively, if the pore-forming material 138 is barely soluble in the paste solvent, a heating method, such as heater heating, heating using electromagnetic waves, or hot air drying, may be used. This drying step removes the paste solvent 137 from the sheet, leaving the gas adsorbent 133, working electrode-side conductive assistant 134, working electrode-side binder 135, and pore-forming material 138 mixed together, as shown in FIG. 7 .

[0044] Next, an extraction process is performed in which an extraction solvent is added to the dried sheet and the pore-forming material 138 is dissolved and extracted in the extraction solvent. The extraction process can be performed, for example, by simply immersing the sheet in water, adding heated water to the sheet, or immersing the sheet in a water stream. Furthermore, the extraction process can be performed by applying ultrasonic waves or using nanobubbles to increase the extraction rate of the pore-forming material 138 and reduce the amount of material remaining in the sheet. As a result of this extraction process, the first electrode film 132 is composed of a gas adsorbent 133, a working electrode-side conductive assistant 134, and a working electrode-side binder 135, and has numerous voids 136 formed in the film, as shown in FIG. 7 .

[0045] The above is the process for forming the first electrode film 132. According to this formation process, the sheet contains pore-forming material 138, which is an inorganic salt that does not shrink during the drying process, and the inorganic salt is extracted and removed with an extraction solvent after drying, so there is no need to expose the sheet to high temperatures, and the first electrode film 132 having voids 136 can be formed while maintaining the film structure. Furthermore, during the drying process, the pore-forming material 138 remains solid at the size it had when added in the second kneading process, so it is easy to control the diameter and number of voids 136 obtained by removing the pore-forming material 138 in the extraction process.

[0046] Another method for forming voids (pores) using a pore-forming material is to use an organic substance as the pore-forming material, and after forming the sheet, heat it at a high temperature to burn off the pore-forming material. However, this method is not preferable from the viewpoint of ensuring the gas adsorption rate, because when organic substances are used as the gas adsorbent 133 or the working electrode side binder 135, these materials are lost or damaged in the process of burning off the pore-forming material.

[0047] Even when a pore-forming material is not used, some voids may be formed by drying the paste solvent 137 from the sheet body, but in this case, it is difficult to design the diameter of the voids because the working electrode-side binder 135 shrinks due to tension when the paste solvent 137 evaporates. Furthermore, it is difficult to control the voids in the sheet body by the amount of paste solvent 137 for reasons such as the difference between the solvent ratio in the paste and the gas phase ratio in the sheet body after drying, and the paste solvent ratio being limited so as to fall within a viscosity range that allows the sheet body to be coated.

[0048] According to this embodiment, the gas adsorption system 100 includes an electrochemical cell 110 having a structure in which the first electrode film 132 that absorbs gas on the working electrode has a plurality of voids 136 with a diameter equal to or greater than the mean free path of the gas, and the voids 136 function as vapor-phase passages for the gas. Therefore, compared to a structure without voids 136, this gas adsorption system 100 includes the first electrode film 132 that improves the speed at which the gas reaches the gas adsorbent 133 on the working electrode, thereby achieving the effect of further improving the gas adsorption speed.

[0049] The method for manufacturing the electrochemical cell 110 also includes forming a sheet by applying a paste containing a gas adsorbent 133, a paste solvent 137, and a pore-forming material 138, drying and removing the paste solvent from the sheet, and then extracting the pore-forming material 138 using an extraction solvent. The removal of the pore-forming material 138 in the extraction step forms a plurality of voids 136, forming a first electrode film 132 in which the plurality of voids 136 function as vapor-phase passages for gas. Therefore, compared to a structure without voids 136, the speed at which gas reaches the gas adsorbent 133 at the working electrode is increased, making it possible to manufacture an electrochemical cell 110 with an improved adsorption speed for the gas to be adsorbed.

[0050] (Second embodiment) A gas adsorption system 100 according to a second embodiment will be described.

[0051] 8, the gas adsorption system 100 of this embodiment differs from the first embodiment in that the first electrode film 132 has an electrolyte material 139, and the electrolyte material 139 is gelled. This difference will be mainly described in this embodiment.

[0052] In this embodiment, as shown in FIG. 8, the first electrode film 132 further includes an electrolyte material 139 in addition to a gas adsorbent 133, a working electrode side conductive additive 134, and a working electrode side binder 135, and has a plurality of voids 136 formed therein.

[0053] The electrolyte material 139 is in contact with the gas adsorbent 133 and contains ions. The ions are transferred to the gas adsorbent 133, thereby correcting the charge imbalance in the gas adsorbent 133. The electrolyte material 139 is preferably one that does not dissolve the pore-forming material 138 and is insoluble in the extraction solvent. For example, the ionic liquid described above in the first embodiment can be used. At least a portion of the electrolyte material 139 gels together with the working electrode binder 135 during the process of forming the first electrode film 132, which will be described later, to form a non-fluidic gel electrolyte as a whole. This fixes the electrolyte material 139 to the first current collector 131 in a gelled state, preventing imbalance due to the influence of airflow, gravity, and the like during operation of the gas adsorption system 100. This improves the flexibility of mounting the electrochemical cell 110.

[0054] Next, the process of forming the first electrode film 132 of this embodiment will be described with reference to Fig. 9. Note that since this embodiment includes steps common to the first embodiment, only differences from the first embodiment will be described here.

[0055] The process for forming the first electrode film 132 according to this embodiment is similar to that for the first electrode film 132 in terms of the first and second kneading steps and the sheet body application step, but includes an electrolyte solution application step before the sheet body drying step.

[0056] The electrolyte solution application step can be performed by, for example, any application method that can apply the electrolyte solution, i.e., the electrolyte material 139, approximately uniformly to the surface of the sheet body. Examples of the application method include spray coating, dip coating, bar coating, liquid immersion, vacuum impregnation, and inkjet printing. By applying the electrolyte solution, the sheet body becomes a mixture of a gas adsorbent 133, a working electrode-side conductive additive 134, a working electrode-side binder 135, a paste solvent 137, and an electrolyte material 139, as shown in FIG. 9. Then, by applying the electrolyte solution, the polymer material (working electrode-side binder 135) in the sheet body swells and gels with the electrolyte solution (electrolyte material 139), forming a gel electrolyte.

[0057] Next, the sheet body to which the electrolytic solution has been supplied in the above-mentioned coating process is subjected to a drying process in which the paste solvent 137 is evaporated by any method such as heating, air drying, or vacuum drying. In this drying process, the paste solvent 137 that has dissolved the working electrode-side binder 135 is volatilized from the sheet body, leaving only the electrolytic solution. In the drying process, the sheet body is gelled, and a gel electrolyte having a pore-forming material 138 dispersed therein is contained, and the sheet body as a whole becomes a non-fluid plate.

[0058] Finally, the gelled sheet is subjected to an extraction process in which water is used as an extraction solvent to extract and remove the pore-forming material 138, as in the first embodiment. This allows the formation of a first electrode film 132 based on the gel electrolyte and having numerous voids 136 formed therein.

[0059] The above is the process for forming the first electrode film 132 in the electrochemical cell 110 of this embodiment.

[0060] The present embodiment also provides the gas adsorption system 100 with the same effects as those of the first embodiment. Furthermore, the first electrode film 132 has the electrolyte material 139 that conducts ions and is in contact with the gas adsorbent 133, and the electrolyte material 139 is in a gelled state and has no fluidity, so that the effects of improving ion conductivity and maintaining the voids 136 are achieved at the same time.

[0061] (Other embodiments) Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one, or less than one, are also within the scope and spirit of the present disclosure.

[0062] It goes without saying that in each of the above embodiments, the elements constituting the embodiments are not necessarily essential unless they are specifically stated as essential or are clearly considered essential in principle. Furthermore, in each of the above embodiments, when numerical values ​​such as the number, values, amounts, and ranges of the components of the embodiments are mentioned, they are not limited to the specific numbers unless they are specifically stated as essential or are clearly limited to a specific number in principle. Furthermore, in each of the above embodiments, when the shapes, positional relationships, etc. of the components are mentioned, they are not limited to the shapes, positional relationships, etc., unless they are specifically stated or are clearly limited to a specific shape, positional relationship, etc. in principle. [Explanation of symbols]

[0063] 110 Electrochemical Cell 130 1st electrode (working electrode) 132 First electrode film 133 Gas absorbent 136 Cavity 137 Paste Solvent 138 Pore forming material 140 Second electrode (counter electrode) 150 Separator

Claims

1. A method for manufacturing an electrochemical cell (110) including a working electrode (130) having an electrode film (132) that adsorbs a predetermined gas, a counter electrode (140), and a separator (150) disposed between the working electrode and the counter electrode, comprising: a paste including a gas adsorbent (133) for adsorbing the gas, a paste solvent (137), and a pore-forming material (138) composed of an inorganic salt and having a particle size equal to or smaller than the thickness of the electrode film is applied to form a sheet body; drying the sheet body to remove the paste solvent; applying an extraction solvent to the dried sheet body to extract the pore-forming material from the sheet body, thereby forming the electrode film having voids (136).

2. The method for manufacturing an electrochemical cell according to claim 1 , wherein the pore-forming material has the highest solubility in water among the materials contained in the paste.

3. The method for manufacturing an electrochemical cell according to claim 1 , wherein the pore-forming material has a melting point or a thermal decomposition temperature higher than a drying temperature in the step of drying the sheet body.

4. The method for manufacturing an electrochemical cell according to claim 1 , wherein the particle size of the pore-forming material is larger than the mean free path of the predetermined gas.

5. The method for producing an electrochemical cell according to claim 1 , wherein the step of removing the paste solvent is carried out at a temperature lower than a process temperature in the step of extracting the pore-forming material.

6. The method for manufacturing an electrochemical cell according to claim 1 , further comprising applying an electrolyte solution to the sheet body and gelling the electrolyte solution before drying the sheet body.

7. 1. An electrochemical cell comprising: a working electrode (130) having an electrode film (132) that adsorbs a predetermined gas; a counter electrode (140) that pairs with the working electrode; a separator (150) disposed between the working electrode and the counter electrode; The electrochemical cell has a plurality of voids (136) therein, each void having a diameter equal to or greater than the mean free path of the predetermined gas.

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