Manufacturing device and method for producing electrochemical cells

Abstract

A manufacturing apparatus (100) for manufacturing an electrochemical cell having an outer body (210) under reduced pressure, the manufacturing apparatus comprising: a chamber (110); a pressure reducing device (130); and a return line (140), wherein the pressure reducing device (130) is designed to reduce a pressure in the chamber (110), the return line (140) contains a first opening (141), a line (143) and a second opening (142), the first opening (141) and the second opening (142) are each independently open to the interior of the chamber (110), the first opening (141) is connected to the outer body (210), the line (143) connects the first opening (141) to the second opening (142), and the conduit (143) is designed to once draw a gas in the outer body (210) from the chamber (110) when the pressure in the chamber is reduced and then return the gas to the chamber.

Description

1. Field of the InventionThe disclosure relates to a manufacturing apparatus and a method for manufacturing electrochemical cells.2. Description of the Prior ArtJapanese Unexamined Patent Publication No. 2018-106850 (JP 2018-106850 A) discloses an injection device and an injection method that can improve the manufacturing efficiency of energy storage modules.JP 2019-153538 A, which is considered as the closest prior art, discloses a liquid injection device and a liquid injection method with which gas is extracted from a bag-shaped film outer body through a nozzle inserted into the film outer body.Generally, electrochemical cells (which may be abbreviated as "cells") are manufactured by including, for example, power generating elements and an electrolyte in an outer body. In use of the cells, gas may form in the outer body, for example, due to deterioration of the electrolyte. With the gas generation, the internal pressure in the outer body can be increased. In view of the later gas formation, it is desirable to reduce the gas in the outer body as much as possible at the manufacturing stage. Thus, the pressure in the outer body can be reduced. For example, the pressure in the outer body can be reduced by a vacuum pump, etc. After the pressure (degree of pressure reduction) in the outer body reaches a target value, the outer body is sealed.In some cases, an outer body of low rigidity is used. For example, a sheet-like or sheet-like outer body such as a metal foil composite or laminate film may be used. When the rigidity of the outer body is low, the outer body may be pressed and deformed by the external pressure when the pressure in the outer body is decreased. With the outer body thus deformed, a gas channel can be blocked. When the gas passage is blocked, there is a possibility that the target degree of pressure reduction in the outer body is not reached even when a value indicated by a pressure gauge reaches a target value.The disclosure provides a manufacturing apparatus and a method for manufacturing an electrochemical cell that guarantee the internal pressure in an outer body by reducing a blockage of a gas channel when the pressure in the outer body is reduced.A manufacturing apparatus according to a first aspect of the invention is a manufacturing apparatus for manufacturing an electrochemical cell having an outer body under reduced pressure. The manufacturing apparatus includes a chamber, a pressure reducing device, and a return line. The pressure reducing device is configured to reduce / reduce a pressure in the chamber. The return conduit includes a first port, a conduit, and a second port. The first opening and the second opening are each and independently open to the interior of the chamber. The first opening is connected to the outer body. The conduit connects the first opening to the second opening. The conduit is designed to draw a gas in the outer body from the chamber once the pressure in the chamber is reduced and then to recycle the gas into the chamber.In the manufacturing apparatus according to the first aspect, the return line may include a plurality of return lines that are independent of each other. Each of the return lines may include the first port, the line, and the second port.The manufacturing apparatus according to the first aspect may further include a pressure measurement device. The pressure gauge may be connected to the conduit.The manufacturing apparatus according to the first aspect may further include a flowmeter. The flow meter may be connected to the conduit.The manufacturing apparatus according to the first aspect may further include a sealing device. The sealing device may be configured to seal the outer body in the chamber.A method of manufacturing an electrochemical cell according to a second aspect of the invention includes: preparing a workpiece by enclosing a power generation element in the outer body; disposing the workpiece in the chamber; connecting the outer body to the first opening; and reducing a pressure in the chamber to reduce a pressure in the outer body via the return line.In the method according to the second aspect, in the preparation of the manufacturing apparatus, the manufacturing apparatus including a plurality of return lines independent of each other may be prepared. In preparing the workpiece, a cell module including a plurality of electrochemical cells may be prepared as the workpiece. The electrochemical cells may each and independently contain interior spaces. When connecting the outer body to the first opening, the return lines, which are separated from each other, may be connected to the internal spaces, respectively.In the method according to the second aspect, in the preparation of the manufacturing apparatus, the manufacturing apparatus including a pressure gauge may be prepared. In reducing the pressure in the outer body, the pressure in the outer body may be reduced so far that a value indicated by the pressure gauge becomes equal to or greater than a reference value.In the method according to the second aspect, in the preparation of the manufacturing apparatus, the manufacturing apparatus including a flow meter may be prepared. In reducing the pressure in the outer body, the pressure in the outer body may be reduced so far that an integrated value of measurement values of the flowmeter becomes equal to or larger than a reference value after completion of the pressure reduction.The method according to the second aspect may further include injecting an electrolyte into the outer body through an injection hole formed in the outer body. When connecting the outer body to the first opening, the first opening of the return line may be connected to the injection hole.In the method according to the second aspect, the outer body may include at least one type selected from the group consisting of a metal foil and a metal foil composite film.In the method, in preparing the workpiece, a bipolar cell module may be prepared as the workpiece.The method according to the second aspect may further include sealing the outer body under reduced pressure.Hereinafter, an embodiment of this disclosure (which may be abbreviated as "this embodiment") and an example of this disclosure (which may be abbreviated as "example") will be described. However, the technical scope of this disclosure is not limited to this embodiment and the example.Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein: FIG. 1 is a first conceptual diagram of a reduced pressure state; FIG. 2 is a second conceptual diagram of a reduced pressure state; FIG. 3 is a conceptual diagram showing an example of a cell module; FIG. 4 is a conceptual diagram showing an example of a manufacturing apparatus of the embodiment; FIG. 5 is a schematic flow diagram of a method for manufacturing an electrochemical cell according to the embodiment; FIG. 6 is a schematic cross-sectional view of a first unit, a second unit, and a third unit in the embodiment; FIG. 7 is a schematic cross-sectional view of a bipolar cell module in the embodiment; FIG. 8 is a schematic plan view of the bipolar cell module in the embodiment; and FIG. 9 is a conceptual diagram showing a comparative example.Definition of Expressions, etc.In this specification, the terms "comprising," "including," "with," and variations thereof (e.g., "comprises") are not exhaustive. The non-exhaustive terms may or may not include other elements in addition to the necessary elements. The term "consisting of" is inclusive. However, even the final term does not exclude additional elements that are normally associated contaminants or irrelevant to the disclosed technique. The term "consisting essentially of... " is semi-exhaustive. In final terms of elements, the addition of elements that have substantially no impact on the basic and novel characteristics of the disclosed technology is permitted.In this specification, terms such as "can" ("can do" or "can do") are used in the allowed sense rather than "need to" in the mandatory sense.In this specification, the order of multiple steps, actions, and operations of various methods is not limited to the order in the description unless otherwise stated. For example, two or more steps may be performed simultaneously. For example, two or more steps may be performed in front of or behind one another.Geometric terms (e.g., "parallel", "perpendicular", "orthogonal", etc.) should not be interpreted in a strict sense in this specification. For example, "parallel" may deviate somewhat from "parallel" in a strict sense. The geometric terms in this specification may include, for example, tolerances, errors, etc. in design, operation, manufacture, etc. The spatial relationships in each figure may deviate from the actual spatial relationships. In some cases, the spatial relationships (length, width, thickness, etc.) of the individual figures are altered to better understand the disclosed technology. Furthermore, some configurations may be omitted.In this specification, "electrochemical cell" refers to a single device that converts chemical energy into electrical energy. The electrochemical cells include primary batteries and secondary batteries. The electrochemical cells include lithium ion batteries and nickel metal hydride batteries. The lithium ion batteries include liquid batteries and all solid state batteries. In this specification, "cell module" refers to a collection of multiple electrochemical cells. The electrochemical cells may or may be electrically connected to each other, but need not be. The electrochemical cells may be connected in series or in parallel.In this specification, the "degree of depressurization" refers to the amount of pressure of the gas remaining in an outer body after depressurization. The degree of the pressure reduction may also refer to the "degree of vacuum".Outline of the EmbodimentNext, a brief description of these embodiments will be described first. The operating mechanism of this description involves assumptions. The operation mechanism does not limit the embodiment.1. A manufacturing apparatus can manufacture an electrochemical cell in which pressure in an outer body is reduced. The manufacturing apparatus includes a chamber, a pressure reducing device, and a return line. The pressure reducing device is configured to reduce the pressure in the chamber. The return conduit includes a first port, a conduit, and a second port. The first opening and the second opening are each and independently open to the interior of the chamber. The first opening is configured to be connectable to the outer body. The conduit connects the first opening to the second opening. The conduit extends to draw once gas in the outer body from the chamber as the pressure in the chamber is reduced and then return the drawn gas to the chamber.FIG. 1 is a first conceptual diagram of a reduced pressure state. When the gas in the outer body 210 is discharged, the internal pressure P I in the outer body 210 becomes lower than the external pressure P E. That is, the inside of the outer body 210 is brought into a negative pressure state relative to the ambient atmosphere. The inner space of the outer body 210 may be compressed by the external pressure P E which may result in a blockage of a gas channel.FIG. 2 is a second conceptual diagram of a reduced pressure state. In Fig. 2, the white arrows show a gas flow. In the manufacturing apparatus of the above item "1", the gas in the outer body 210 can be discharged via the return pipe 140. When the pressure in the chamber 110 is decreased, the pressure of the chamber 110 (the external pressure P E) is decreased. A pressure loss can be generated in the return line 140. As a result, the internal pressure P I in the outer body 210 may become higher than the external pressure P E. That is, the inside of the outer body 210 may be brought into an over-pressure state relative to the ambient atmosphere (the atmosphere in the chamber 110). It is assumed that when the positive pressure state is maintained during the pressure reduction, the inner space of the outer body 210 is less likely or unlikely to be compressed by the external pressure P E. That is, it is assumed that blockage of the gas channel is likely or unlikely to occur.2. The manufacturing apparatus may include a plurality of return lines. The return lines, which are independent of each other, each include the first opening, the line, and the second opening.The manufacturing apparatus of the above item "1" may generate a single cell, for example. The manufacturing apparatus of the above item "2" may generate a cell module. The manufacturing apparatus of the above item "2" is considered suitable for manufacturing cell modules.FIG. 3 is a conceptual diagram showing an example of a cell module. The cell module 250 includes partitions 230. The partition wall 230 separates adjacent cells 200 from each other. When any gas channel is blocked due to deformation of the outer body 210 in an outer cell 200, the blocking may be recognized by the outer appearance. The white arrows in FIG. 3 show an example of the deformation direction. For example, when any gas passage is blocked in an inner cell 200 due to deformation of the partition wall 230, it is difficult to recognize blocking by the outer appearance.By connecting separate return lines to the individual cells, it is possible to reduce the pressure in the individual cells and at the same time to keep the cell in the overpressure state. Thus, blockage of gas channels in the inner cells is reduced.In the manufacturing apparatus of the above item "2", the object whose pressure is reduced is a single chamber. Thus, the pressures in multiple cells can be simultaneously reduced by a single pressure reducing device.3. The manufacturing apparatus may further include a pressure gauge. The pressure gauge is connected to the conduit.The pressure gauge may be used to check the degree of pressure reduction of each individual cell.4. The manufacturing apparatus may further include a flow meter. The flow meter is connected to the conduit.For example, the total amount of the discharged gas can be obtained by integrating the measurement values of the flowmeter. For example, the degree of pressure reduction in the individual cells can be determined from the total amount of the discharged gas and the inner space (volume) of the outer body.5. The manufacturing apparatus may further include a sealing apparatus. The sealing device may seal the outer body in the chamber.6. A method of manufacturing an electrochemical cell includes the following steps (a) to (e). (a) preparing the manufacturing apparatus of the above item "1". (b) preparing a workpiece by enclosing the power generating elements in the outer body. (c) disposing the workpiece in the chamber. (d) connecting the outer body to the first opening. (e) reducing the pressure in the chamber and thereby reducing the pressure in the outer body via the return line.The manufacturing apparatus of the above item "1" can be used in the method of the above item "6", for example.7. In the above step (a), a manufacturing apparatus including, for example, a plurality of return lines independently may be prepared. In the above step (b), a cell module including a plurality of electrochemical cells may be prepared as the workpiece. The electrochemical cells each and independently contain interior spaces. In the above step (d), separate return lines may be connected to the respective interiors.In the manufacturing method of the above item "7", the cell module can be manufactured. The cell module may be of the bipolar type or of the momonopolar type. In the bipolar type, each electrode has two polarities. For example, the front side of the electrode is a positive electrode and the back side is a negative electrode. The electrode may be referred to as a "bipolar electrode.". In the monopolar type, each electrode has a single polarity. That is, the electrode is either a positive electrode or a negative electrode.8. In the above step (a), a manufacturing apparatus including, for example, a pressure gauge may be prepared. In the above step (e), the pressure in the outer body may be decreased so far that the value indicated by the pressure gauge becomes equal to or greater than a reference value.For example, the degree of pressure decrease may be checked by the pressure gauge.9. In the above step (a), a manufacturing apparatus including a flowmeter may be prepared. In the above step (e), the pressure in the outer body may be decreased so far that the integrated value of the measurement values of the flowmeter at the end of the decrease of the pressure is equal to or greater than a reference value.For example, the degree of pressure reduction may be checked by the flowmeter. For example, the degree of pressure reduction may be checked by both the pressure gauge and the flowmeter.10. An injection hole may be formed in the outer body. The electrolyte may be injected into the outer body via the injection hole. In the above step (d), the first opening of the return line may be connected to the injection port.For example, gas may be discharged from the injection hole of the outer body.11. The outer body may include at least one type selected from the group consisting of a metal foil and a metal foil composite film.The metal foil and metal foil composite film may have low rigidity. The manufacturing method of the above item "6" is suitable for the case where the rigidity of the outer body is low.12. In the above step (b), a bipolar cell module may be prepared as the workpiece.The manufacturing method of the above item "7" is suitable for manufacturing bipolar cell modules. 13.The method for manufacturing the electrochemical cell may further include the following step (f).(f) Sealing the outer body under reduced pressure.Details of EmbodimentDetails of the embodiments will be described below.Manufacturing ApparatusFIG. 4 is a conceptual diagram showing an example of the manufacturing apparatus of this embodiment. The "manufacturing apparatus of this embodiment" may be simply referred to as "the manufacturing apparatus". The manufacturing apparatus 100 includes a chamber 110, a pressure reducing apparatus 130, and return pipes 140. The manufacturing apparatus 100 may further include, for example, sealing apparatuses 120, pressure gauges 150, flow meters 160, etc.The chamber 110 may provide a stable, sealed space in a reduced pressure state. The chamber 110 may be, for example, a metal container. The chamber 110 may include, for example, an outlet or exhaust port 111. The outlet 111 may be connected to the pressure reducing device 130. For example, a stage, a holder, or the like (not shown in FIG. 4 ) may be provided in the chamber 110. The workpiece 201 can be held by the stage, the holder, or the like.For example, the sealing device 120 may seal the outer body 210 within the chamber 110. For example, the sealing device 120 may seal the outer body 210 outside the chamber 110. The sealing device 120 may seal the outer body 210 by any method. The sealing device 120 may include, for example, a thermal welding device, ultrasonic welding device, etc. The sealing device 120 may be disposed in the chamber 110, for example. For example, a portion of the sealing device 120 may be disposed in the chamber 110. For example, a portion of the sealing device 120 that actually effects the sealing may be disposed in the chamber 110. The portion that actually effects the sealing may include, for example, a pressing unit, a heating rod, a heating plate, an ultrasonic horn, an anvil, etc. The sealing device 120 may be disposed outside the chamber 110, for example.The pressure reducing device 130 may reduce the pressure in the chamber 110. The pressure reducing device 130 may include, for example, a vacuum pump, a compressor, etc.The return lines 140 may be strong enough not to be deformed by external pressure during the pressure reduction. The return lines 140 may be made of metal, for example. The return lines 140 include a first port 141, a line 143, and a second port 142. The first opening 141 and the second opening 142 are each and independently open to the inside of the chamber 110. The positions of the first opening 141 and the second opening 142 can be determined at will provided they do not take the same position. The first opening 141 is connected to the outer body 210. For example, a jig ("jig") for connecting the return pipe 140 to the outer body 210 may be fixed to the first opening 141.The conduit 143 connects the first opening 141 to the second opening 142. The first opening 141 is disposed at one end of the pipe 143. The second opening 142 is disposed at the other end of the conduit 143. In FIG. 4, white arrows show a gas flow. The conduit extends to draw the gas in the outer body 210 from the chamber 110 once the pressure in the chamber 110 is reduced and then return the drawn gas to the chamber 110. That is, when the pressure in the chamber 110 is decreased, the gas in the outer body 210 is exhausted from the first opening 141. The exhausted gas passes through the conduit 143 and is directed through the second port 142 to the interior of the chamber 110. It is assumed that a pressure loss is generated in the pipe 143. Due to the pressure loss, the inside of the outer body 210 may be in a positive pressure state relative to the atmosphere in the chamber 110. The pressure in the outer body 210 which is in the positive pressure state is reduced to such an extent that blockage of the gas passage in the outer body 210 can be reduced.For example, the conduit 143 may have an inner diameter of 1 to 10 mm or an inner diameter of 2 to 6 mm. When the inner diameter of the pipe 143 is in the range of 1 to 10 mm, an appropriate pressure loss can be generated. The inner diameter of the conduit 143 may be constant or variable. The pressure loss may be generated by a change in the inner diameter. The conduit 143 may have two or more manifolds. Pressure loss may occur at the manifolds.The manufacturing apparatus 100 may include a single return lines 140. The manufacturing apparatus 100 may include two or more return lines 140. Three return lines 140 are shown as an example in FIG. 4. Each of the two or more return lines 140 that are independent of each other includes the first port 141, the line 143, and the second port 142. With the manufacturing apparatus 100 including the two or more return lines 140, the cell module 250 may be manufactured. The number of return lines 140 may correspond to the number of cells 200 included in the cell module 250.The manufacturing apparatus 100 may further include a pressure measurement device 150. The pressure gauge 150 is connected to the conduit 143. Depending on the target degree of pressure reduction, the pressure gauge 150 having an appropriate pressure range may be selected. The degree of the pressure decrease in the outer body 210 may be determined from the value indicated by the pressure gauge 150. When the manufacturing apparatus 100 includes two or more return lines 140, the pressure gauge 150 may be connected to each of the return lines 140.The manufacturing apparatus 100 may further include a flow meter 160. The flow meter 160 is connected to the conduit 143. Depending on the gas flow rate, the flow meter 160 having an appropriate flow area may be selected. The gas flow rate is measured by the flow meter 160. The integrated value of the measured values is the total amount of discharged gas. The degree of the pressure reduction in the outer body 210 may be determined from the total amount of the discharged gas and the inner space of the outer body 210. When the manufacturing apparatus 100 includes two or more return lines 140, the flow meter 160 may be connected to each of the return lines 140.Manufacturing Method of Electrochemical CellFIG. 5 is a schematic flow diagram of a method for manufacturing an electrochemical cell according to this embodiment. In the following description, the "method for manufacturing an electrochemical cell according to this embodiment" is briefly referred to as "the manufacturing method". The manufacturing method includes (a) preparing a manufacturing apparatus, (b) preparing a workpiece, (c) arranging the workpiece, (d) connecting to the return pipe, and (e) depressurizing. The manufacturing method may further include, for example, (f) sealing, etc. The order of description in FIG. 5 is merely exemplary. For example, the order of (a) preparation of the manufacturing apparatus and (b) preparation of the workpiece may be reversed.(a) Preparing of Manufacturing ApparatusThe manufacturing method includes preparing the manufacturing apparatus 100. The details of the manufacturing apparatus 100 are described above.(b) Preparing the workpieceThe manufacturing method includes preparing the workpiece 201 by including the power generation elements 220 in the outer body 210. The workpiece 201 is a so-called "pre-sealed cell". For example, a bipolar cell module may be prepared as the workpiece 201. The bipolar cell module includes a plurality of cells. The bipolar cell module may contain, for example, 1 to 100 cells or 10 to 50 cells or 20 to 40 cells. Here, the "bipolar cell module" is simply referred to as "cell module".FIG. 6 is a schematic cross-sectional view of a first unit, a second unit, and a third unit in this embodiment. The first unit 251, the second unit 252, and the third unit 253 may form the cell module 250. The first unit 251 and the third unit 253 are disposed at opposite ends in the stacking direction (Z-axis direction). The second units 252 are stacked between the first unit 251 and the third unit 253.The outer body 210 is in the form of a blade. The outer body 210 may serve as a current collector. The outer body 210 may include at least one type selected from the group consisting of a metal foil and a metal foil composite film. The metal foil composite film may be formed by covering a metal foil with a resin layer. The resin layer may include, for example, polypropylene (PP), polyethylene terephthalate (PET), etc. The metal foil may include at least one type selected from the group consisting of an aluminum (Al) foil, a stainless steel (SUS) foil, a nickel (Ni) foil, a titanium (Ti) foil, and a copper (Cu) foil. For example, the metal foil may be coated. For example, the SUS film may be coated with Ni. The outer body 210 may include at least one type selected from the group consisting of, for example, an Al foil and an Al foil composite film.The first unit 251 is prepared by forming the positive electrode layer 10 on a surface of an outer body 210. The positive electrode layer 10 contains a positive electrode active material. The positive electrode active material may include, for example, lithium nickel cobalt manganate and lithium iron phosphate. The positive electrode layer 10 may further include, for example, a conductive material, a binder, a solid electrolyte, etc.The negative electrode layer 20 is formed on a surface of the other outer body 210. The negative electrode layer 20 contains a negative electrode active material. The negative electrode active material may include, for example, graphite, silicon, silicon oxide, etc. The negative electrode layer 20 may further include, for example, a conductive material, a binder, a solid electrolyte, etc. The third unit 253 is prepared by attaching the separator 30 to a surface of the negative electrode layer 20. The separator 30 may include, for example, a porous film. The porous film may contain, for example, polyolefins, etc. The separator 30 may include, for example, a solid electrolyte layer.The partition wall 230 is in the form of a sheet. The partition wall 230 may be formed of the same materials as the outer body 210 or of different materials than the outer body 210. The partition wall 230 may serve as a current collector. The partition wall 230 may include, for example, a metal foil. The partition wall 230 may include, for example, Al foil, etc. The positive electrode layer 10 is formed on a surface of the partition wall 230. The negative electrode layer 20 is formed on the surface opposite to the surface on which the positive electrode layer 10 is formed. The positive electrode layer 10, the partition wall 230, and the negative electrode layer 20 are combined to form a bipolar electrode. In the bipolar electrode, the separator 30 is fixed to a surface of the negative electrode layer 20 so that the second unit 252 is prepared.FIG. 7 is a schematic cross-sectional view of the bipolar cell module in this embodiment. The first unit 251, the second unit 252,..., the second unit 252, and the third unit 253 are stacked together to form the cell module 250. A set of the positive electrode layer 10, the separator 30, and the negative electrode layer 20 constitute the power generation element 220. The power generation element 220 is formed by two partition walls 230 so that the cell 200 is formed. At the opposite ends in the stacking direction, the power generation element 220 is disposed between the partition wall 230 and the outer body 210 so that the cell 200 is formed. The cells 200 each independently contain an interior space.The outer body 210 includes a sealing material 240. For example, the sealing material 240 may be provided to fill the vicinity of the power generation elements 220. The sealing material 240 may include, for example, a thermoplastic resin (such as PP). The injection ports 241 formed in a part of the sealing material 240 may be formed. That is, the injection ports 241 may be formed in the outer body 210. The injection hole 241 is a hole that can provide a liquid passage and a gas passage. The electrolyte may be injected into the individual cells 200 through the injection hole 241. That is, the electrolyte may be injected into the outer body 210 through the injection hole 241.FIG. 8 is a schematic plan view of the bipolar cell module in this embodiment. The planar shape of the cell module 250 may be selected as needed. The planar shape of the cell module 250 may be, for example, a rectangular shape. The sealing material 240 may surround the periphery of the outer body 210. FIG. 7 is a cross-sectional view taken along line A-A in FIG. 8.For example, a monopolar cell module may be prepared as the workpiece 201. For example, the partition wall 230 may be made of two or more plate-like members. In this case, the positive electrode layer 10 is formed on a surface of one of the plate-like members of the partition wall 230. The negative electrode layer 20 is formed on a surface of the other plate-like member of the partition wall 230. The monopolar cell is formed by placing the one plate-like member on the other plate-like member so that the positive electrode layer 10 and the negative electrode layer 20 are opposed to each other. Between adjacent monopolar cells, the surface opposite to the surface on which the positive electrode layer 10 of the one plate-like element contained in one cell is formed is placed on the surface opposite to the surface on which the negative electrode layer 20 of the other plate-like element contained in the other cell is formed, so that the monopolar cell module is formed.(c) Arrangement of WorkpieceThe manufacturing method includes disposing the workpiece 201 in the chamber 110. For example, the workpiece 201 into which the electrolyte has been injected may be disposed in the chamber 110 (see FIG. 4 ).(d) Connection to the return lineThe manufacturing method includes connecting the outer body 210 to the first opening 141 (return pipes 140) (see FIG. 4 ). For example, the injection hole 241 may be connected to the first hole 141. In the case of the cell module 250, separate return lines 140 may be connected to the injection ports 241 of the respective cells 200. The outer body 210 may include a gas outlet port (not shown) separate from the injection ports 241. The gas outlet connection can serve as a gas channel.(e) Pressure ReductionThe manufacturing method includes reducing the pressure in the chamber 110 and thereby reducing the pressure in the outer body 210 via the return lines 140 (see FIG. 4 ). The pressure in the chamber 110 can be reduced by the pressure reducing device 130. A pressure loss may be generated in the return line 140.The completion of the pressure decrease may be determined by, for example, the value indicated by the pressure gauge 150. For example, when the value indicated by the pressure gauge 150 is equal to or greater than a reference value, it may be determined that the target degree of pressure reduction has been reached. That is, the pressure in the outer body 210 may be decreased so far that the value indicated by the pressure gauge 150 becomes equal to or greater than the reference value.The completion of the pressure reduction may be determined by, for example, the flow meter 160. For example, when the integrated value of the measurement values of the flowmeter 160 (the total amount of discharged gas) after the completion of the pressure reducing device 130 is equal to or greater than the reference value, it may be determined that the target degree of pressure reduction has been reached. When the target degree of pressure reduction has not been reached, the pressure reducing device 130 may be restarted.The reference values of the pressure and the flow rate may be set as needed according to the target degree of pressure reduction, the shape of the pipe 143, etc. The target degree of pressure reduction may be, for example, 5 to 50 kPa.(f) SealingThe manufacturing method may include sealing the outer body 210 under reduced pressure. Thus, the cell module 250 is sealed. The cell module 250 includes a plurality of cells 200. For example, in the chamber 110, the injection ports 241 may be sealed by the sealing devices 120. For example, hot pressing melts and solidifies the sealing material 240. The sealing material 240 may block the injection ports 241 (see FIG. 7 ). For example, the injection ports 241 may be blocked outside the chamber 110.Experiment ExperimentIn this experiment, the cell module 250 was prepared as the workpiece 201. The cell module 250 was of the bipolar type. Cell module 250 contained five cells 200.Example:In the example, the manufacturing apparatus 100 was used (see FIG. 4 ). Separate return lines 140 were connected to the five cells 200, respectively. The pressure in the chamber 110 has been reduced so that the pressure in the outer body 210 has been reduced via the return lines 140. The outer body 210 was sealed to the desired degree of pressure reduction. Whether the target degree of pressure reduction has been achieved was determined by using both the pressure gauges 150 and the flow meters 160.Comparative ExamplesFIG. 9 is a conceptual diagram showing a comparative example. In the comparative example, the cell module 250 was disposed in a chamber 310. The pressure in the chamber 310 was decreased, so that the pressure in the outer body 210 was decreased. By reducing the pressure in chamber 310, the pressures in the five cells 200 were reduced together. After the pressure reduction, the outer body 210 was sealed. The time required for the pressure reduction was the same as that in the example. For example, another pressure gauge may be provided at an outlet port 311 of the chamber 310, and whether the target degree of pressure decrease has been reached may be determined by using the pressure gauge.EvaluationFor each of the five cells 200, the presence or absence of blockage of a gas channel was visually checked. When bulging was observed by residual air in any of the cells 200, a blockage of a gas channel was considered. When no bulging was observed in the cells 200 by residual air, no blocking of a gas channel was assumed.In the example, no blockage of a gas channel was observed. In the example, it was assumed that the internal pressure is ensured in all cells.In the comparative example, blockage of the gas channel was observed. In the comparative example, it was not assumed that the internal pressure is ensured in all the cells.The embodiment and the example are exemplary in all respects. The embodiment and the example are not limiting. The technical scope of this disclosure includes all modifications within the meaning of the scope of the claims and equivalents. For example, it is expected from the beginning to extract arbitrary configurations from the embodiment and the example and to arbitrarily combine the configurations.

Claims

A manufacturing apparatus (100) for manufacturing an electrochemical cell having an outer body (210) under reduced pressure, the manufacturing apparatus comprising: a chamber (110); a pressure reducing apparatus (130); and a return line (140), wherein the pressure reducing device (130) is configured to reduce a pressure in the chamber (110), the return line (140) includes a first opening (141), a line (143), and a second opening (142), the first opening (141) and the second opening (142) are each and independently open to the inside of the chamber (110), the first opening (141) is connected to the outer body (210), the line (143) connects the first opening (141) to the second opening (142), and the line (143) is configured to once draw a gas in the outer body (210) out of the chamber (110) when the pressure in the chamber is reduced, and then return the gas into the chamber.The manufacturing apparatus (100) according to claim 1, wherein: the return line (140) comprises a plurality of return lines (140) independent of each other; and each of the return lines (140) includes the first opening (141), the line (143), and the second opening (142).The manufacturing apparatus (100) according to claim 1 or claim 2, further comprising a pressure gauge (150), wherein the pressure gauge (150) is connected to the conduit (143).The manufacturing apparatus (100) according to any one of claims 1 to 3, further comprising a flow meter (160), wherein the flow meter (160) is connected to the conduit (143).The manufacturing apparatus of any one of claims 1 to 4, further comprising a sealing device (120), wherein the sealing device (120) is configured to seal the outer body (210) in the chamber (110).A method for manufacturing an electrochemical cell, the method comprising: preparing the manufacturing apparatus (100) according to any one of claims 1 to 5; preparing a workpiece (201) by including a power generating element (220) in the outer body (210); disposing the workpiece (201) in the chamber (110); connecting the outer body (210) and the first opening (141); and reducing a pressure in the chamber (110) to reduce a pressure in the outer body (210) via the return line (140).The method according to claim 6, wherein: in preparation of the manufacturing apparatus (100), the manufacturing apparatus including a plurality of the return lines (140) that are independent of each other is prepared; in preparation of the workpiece (201), a cell module including a plurality of the electrochemical cells is prepared as the workpiece; the electrochemical cells each and independently include interiors; and in connecting the outer body (210) to the first opening (141), the return lines (140) that are separate from each other are respectively connected to the interiors.The method according to claim 6 or claim 7, wherein: in the preparation of the manufacturing apparatus (100), the manufacturing apparatus including a pressure gauge (150) is prepared; and in the reduction of the pressure in the outer body (210), the pressure in the outer body is reduced so far that a value indicated by the pressure gauge (150) becomes equal to or greater than a reference value.The method according to any one of claims 6 to 8, wherein: in the preparation of the manufacturing apparatus (100), the manufacturing apparatus including a flowmeter (160) is prepared; and in the reduction of the pressure in the outer body (210), the pressure in the outer body is reduced so far that an integrated value of measurement values of the flowmeter (160) is equal to or greater than a reference value after the completion of the pressure reduction.The method according to any one of claims 6 to 9, further comprising injecting an electrolyte into the inside of the outer body (210) through an injection hole (241) formed in the outer body (210), wherein when the outer body (210) is connected to the first opening (141), the first opening (141) of the return pipe (140) is connected to the injection hole (241).The method according to any one of claims 6 to 10, wherein the outer body (210) includes at least one type selected from the group consisting of a metal foil and a metal foil composite film.The method according to claim 7, wherein in preparing the workpiece (201), a bipolar cell module is prepared as the workpiece.The method of any one of claims 6 to 12, further comprising sealing the outer body (210) under reduced pressure.

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