Inspection apparatus and inspection method

Abstract

To evaluate deviation of a conductive filler.SOLUTION: An inspection device includes a radiation generator that irradiates a strip-shaped resin current collector containing a conductive filler with radiation, a radiation detector that detects the radiation transmitted through the resin current collector, a measurement unit that measures a thickness of the resin current collector, and a control unit that evaluates unevenness of the conductive filler in the resin current collector based on a detection result of the radiation and a measurement result of the thickness.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an inspection device and an inspection method. [Background technology]

[0002] Lithium-ion batteries are high-capacity secondary batteries that have been used in a variety of applications in recent years. An electrode for a lithium-ion battery is composed of an active material layer, a current collector layer, a separator, and a frame that encapsulates the active material layer (see, for example, Patent Document 1). The current collector layer of the electrode can be formed by cutting a strip of current collector (current collector sheet) to a predetermined size.

[0003] The quality of a current collector sheet is closely related to the quality of an electrode manufactured using the current collector sheet. For example, while a current collector sheet is preferably a resin current collector in which conductive filler is uniformly dispersed in a matrix resin, cases in which the conductive filler distribution is uneven are anticipated. Furthermore, it is preferable not to use portions of the current collector sheet in which conductive filler is excessively concentrated or insufficiently concentrated for the manufacture of electrodes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6633866 Summary of the Invention [Problem to be solved by the invention]

[0005] The conductive filler is distributed inside the current collector sheet. In addition, there are cases where there is almost no difference in color between the conductive filler and other parts of the current collector sheet. For these reasons, it is not easy to evaluate the bias of the conductive filler by visual inspection or optical camera images, etc.

[0006] The present invention has been made in view of the above circumstances, and has an object to provide an inspection device and an inspection method that can evaluate the bias of conductive filler. [Means for solving the problem]

[0007] In order to achieve the above object, the inspection device according to the present invention includes a radiation generator that irradiates radiation onto a strip-shaped resin current collector containing a conductive filler, a radiation detector that detects the radiation that has passed through the resin current collector, a measurement unit that measures the thickness of the resin current collector, and a control unit that evaluates the unevenness of the conductive filler in the resin current collector based on the radiation detection results and the thickness measurement results. [Effects of the Invention]

[0008] According to the inspection device and inspection method of the present invention, uneven distribution of conductive filler can be evaluated. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view of a single cell of a battery manufactured using the battery electrode manufacturing apparatus of the first embodiment. [Figure 2] FIG. 2 is a schematic diagram of the battery electrode manufacturing apparatus of the first embodiment. [Figure 3] FIG. 3 is a diagram illustrating an example of the inspection apparatus according to the first embodiment. [Figure 4A] FIG. 4A is a diagram illustrating an example of an X-ray image according to the first embodiment. [Figure 4B] FIG. 4B is a diagram showing an example of the process of acquiring the density of the conductive filler according to the first embodiment. [Figure 5A] FIG. 5A is a diagram showing an example of a mass of conductive filler particles according to the third embodiment. [Figure 5B] FIG. 5B is a diagram showing an example of a mass of conductive filler particles according to the third embodiment.

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings used in the following description may show characteristic portions enlarged for the purpose of emphasizing the characteristic portions, and the dimensional ratios of the components may not be the same as in reality. Also, for the same purpose, some parts may be omitted in the drawings.

[0011] (First embodiment) In the first embodiment, an example will be described in which a detection process for evaluating uneven distribution of conductive filler in a current collector sheet is performed during the manufacturing process of a battery electrode. Specifically, an electrode including an active material layer and a current collector layer is manufactured using a battery electrode manufacturing apparatus described below. The detection apparatus of the first embodiment is incorporated into the battery electrode manufacturing apparatus and evaluates uneven distribution of conductive filler in a current collector sheet for forming a current collector layer.

[0012] <Battery pack (secondary battery)> The battery electrode manufacturing apparatus is applied to, for example, the manufacture of lithium ion batteries. Lithium ion batteries are used in the form of a modularized battery assembly formed by combining multiple lithium ion single batteries (also referred to as single cells or battery cells), or in the form of a battery pack formed by combining multiple such battery assemblies and adjusting the voltage and capacity. While the following will show an example of a lithium ion secondary battery, the type of secondary battery according to the present invention is not limited to a lithium ion secondary battery and includes other secondary batteries.

[0013] <Single cell (battery cell)> 1 is a cross-sectional view of a single cell 10. The above-described battery pack can be produced by combining a plurality of single cells 10. For example, the single cell 10 has two electrodes 20 (battery electrodes), a positive electrode 20a and a negative electrode 20b, and a separator 30.

[0014] The separator 30 is disposed between the positive electrode 20a and the negative electrode 20b. In the assembled battery, the plurality of unit cells 10 are stacked with the positive electrode 20a and the negative electrode 20b facing in the same direction.

[0015] The separator 30 holds an electrolyte. As a result, the separator 30 functions as an electrolyte layer. The separator 30 is disposed between the electrode active material layers 22 of the positive electrode 20a and the negative electrode 20b, and prevents them from contacting each other. As a result, the separator 30 functions as a partition wall between the positive electrode 20a and the negative electrode 20b.

[0016] Examples of the electrolyte held in the separator 30 include an electrolytic solution or a gel polymer electrolyte. The use of these electrolytes ensures high lithium ion conductivity. Examples of the separator form include a porous sheet separator made of a polymer or fiber that absorbs and holds the electrolyte, and a nonwoven fabric separator.

[0017] The positive electrode 20a and the negative electrode 20b each have a current collector layer 21, an electrode active material layer 22, and a frame 35. The electrode active material layer 22 and the current collector layer 21 are arranged in this order from the separator 30 side. The frame 35 is frame-shaped (annular). The frame 35 surrounds the periphery of the electrode active material layer 22. The frame 35 of the positive electrode 20a and the frame 35 of the negative electrode 20b are welded to each other and integrated. Alternatively, the frame 35 of the positive electrode 20a and the frame 35 of the negative electrode 20b may be integrally fabricated from the beginning. That is, the frame 35 of the positive electrode 20a and the frame 35 of the negative electrode 20b may be fabricated separately and then integrated, or may be fabricated as a single member. In the following description, when it is necessary to distinguish between the electrode active material layers 22 of the positive electrode 20a and the negative electrode 20b, they will be referred to as the positive electrode active material layer 22a and the negative electrode active material layer 22b, respectively.

[0018] <Specific examples of positive electrode current collectors> The positive electrode current collector constituting the positive electrode current collector layer 21a can be a current collector used in known lithium-ion cells, such as a known metal current collector or a resin current collector composed of a conductive material and a resin (such as the resin current collectors described in JP 2012-150905 A and WO 2015 / 005116 A). From the viewpoint of battery characteristics, etc., the positive electrode current collector constituting the positive electrode current collector layer 21a is preferably a resin current collector.

[0019] The resin current collector preferably contains a conductive filler and a matrix resin. Examples of the matrix resin include, but are not limited to, polyethylene (PE), polypropylene (PP), and polymethylpentene (PMP). The conductive filler is not particularly limited as long as it is selected from conductive materials. Examples include metal fillers such as nickel, aluminum, stainless steel (SUS), silver, copper, titanium, platinum, gold, and mixtures thereof; non-conductive materials such as particulate ceramic materials and resin materials coated with a metallic conductive material by plating; and conductive carbon fillers such as graphite, carbon black, carbon nanotubes, and mixtures thereof. The conductive filler may be in the form of conductive fibers.

[0020] In addition to the matrix resin and conductive filler, the resin current collector may contain other components (such as a dispersant, a crosslinking accelerator, a crosslinking agent, a colorant, an ultraviolet absorber, and a plasticizer). A plurality of resin current collectors may be stacked, or a resin current collector may be stacked with a metal foil. For example, the surface of the resin current collector may be subjected to a surface treatment to provide a metal layer. The surface of the resin current collector may also be subjected to a surface treatment to provide a metal layer by a method such as sputtering, vapor deposition, plating, electrodeposition, or coating.

[0021] Although the resin current collector has been described, a metal current collector can also be used as the positive electrode current collector. The metal materials described as the conductive filler can be suitably used as the metal current collector. These metal materials can be in the form of a thin plate, metal foil, or the like.

[0022] The thickness of the positive electrode current collector layer 21a is not particularly limited, but is preferably 5 to 150 μm. When a plurality of resin current collectors are stacked to form the positive electrode current collector layer 21a, the total thickness after stacking is preferably 5 to 150 μm. The positive electrode current collector layer 21a can be obtained, for example, by melt-kneading a matrix resin, a conductive filler, and an optional filler dispersant to obtain a conductive resin composition, and then molding the resulting composition into a film using a known method.

[0023] <Specific examples of positive electrode active materials> The positive electrode active material layer 22a is preferably a non-binding mixture containing a positive electrode active material. Here, "non-binding" means that the positions of the positive electrode active materials in the positive electrode active material layer are not fixed, and the positive electrode active materials are not irreversibly fixed to each other. When the positive electrode active material layer 22a is a non-binding layer, the positive electrode active materials are not irreversibly fixed to each other, allowing separation without mechanical destruction of the interfaces between the positive electrode active materials. Even when stress is applied to the positive electrode active material layer 22a, the positive electrode active material moves, preventing destruction of the positive electrode active material layer 22a. The non-binding positive electrode active material layer 22a can be obtained by, for example, converting the positive electrode active material layer 22a into a positive electrode active material layer 22a containing a positive electrode active material and an electrolyte solution but not containing a binder. In this specification, "binder" refers to an agent that cannot reversibly fix the positive electrode active materials to each other or to the current collector. Such binders are used by dissolving or dispersing them in a solvent, and when the solvent is evaporated or distilled off, the surface solidifies without exhibiting any adhesiveness, and therefore cannot reversibly fix the positive electrode active materials together or the positive electrode active material to the current collector.

[0024] Examples of the positive electrode active material include, but are not limited to, composite oxides of lithium and transition metals, composite oxides containing two types of transition metal elements, and composite oxides containing three or more types of metal elements.

[0025] The positive electrode active material may be a coated positive electrode active material in which at least a portion of the surface thereof is coated with a coating material containing a polymer compound. When the periphery of the positive electrode active material is coated with a coating material, volume change of the positive electrode is alleviated, and expansion of the positive electrode can be suppressed.

[0026] As the polymer compound constituting the coating material, those described as resins for coating active materials in JP 2017-054703 A and WO 2015 / 005117 A, etc., can be suitably used.

[0027] The coating material may contain a conductive agent, which may be the same as the conductive filler contained in the positive electrode current collector layer 21a.

[0028] The positive electrode active material layer 22a may contain an adhesive resin. Examples of suitable adhesive resins include those described in JP 2017-054703 A, in which a small amount of organic solvent is mixed with a nonaqueous secondary battery active material coating resin to adjust its glass transition temperature below room temperature, and those described in JP 10-255805 A as adhesives. The adhesive resin refers to a resin that remains tacky even after drying by volatilizing the solvent components and remains tacky (i.e., adheres by application of slight pressure without using water, solvents, heat, etc.). On the other hand, a solution-drying electrode binder used as a binder refers to a material that dries and solidifies by volatilizing the solvent components, thereby firmly adhering and fixing active materials together. Therefore, the binder (solution-drying electrode binder) and the adhesive resin are different materials.

[0029] The positive electrode active material layer 22a may contain an electrolytic solution containing an electrolyte and a non-aqueous solvent. The electrolyte may be any of those used in known electrolytic solutions. The non-aqueous solvent may be any of those used in known electrolytic solutions. For example, a mixed solution of ethylene carbonate (EC) and dimethyl carbonate (DMC), or a mixed solution of ethylene carbonate (EC) and propylene carbonate (PC) may be used.

[0030] The positive electrode active material layer 22a may contain a conductive additive, which may be a conductive material similar to the conductive filler contained in the positive electrode current collector layer 21a.

[0031] The thickness of the positive electrode active material layer 22a is not particularly limited, but from the viewpoint of battery performance, it is preferably 100 to 700 μm, and more preferably 200 to 500 μm.

[0032] In this embodiment, the positive electrode composition supplied to form the positive electrode active material layer 22a is a wet powder containing a positive electrode active material and a nonaqueous electrolyte. The wet powder is preferably in a pendular or funicular state. Alternatively, the positive electrode composition may be a clay-like (semi-solid) positive electrode active material kneaded with an electrolyte.

[0033] The proportion of the non-aqueous electrolyte in the wet powder is not particularly limited, but in order to achieve a pendular or funicular state, in the case of the positive electrode, it is desirable that the proportion of the non-aqueous electrolyte be 0.2 to 40% by weight of the entire wet powder.

[0034] <Specific examples of negative electrode current collectors> The negative electrode current collector constituting the negative electrode current collector layer 21b can be appropriately selected from the same configuration as that described for the positive electrode current collector and can be obtained by the same method. From the viewpoint of battery characteristics, the negative electrode current collector layer 21b is preferably a resin current collector. The thickness of the negative electrode current collector layer 21b is not particularly limited, but is preferably 5 to 150 μm.

[0035] <Specific examples of negative electrode active materials> The negative electrode active material layer 22b is preferably a non-binding mixture containing a negative electrode active material. The reasons why the negative electrode active material layer is preferably a non-binding material and the method for obtaining the non-binding negative electrode active material layer 22b are the same as the reasons why the positive electrode active material layer 22a is preferably a non-binding material and the method for obtaining the non-binding positive electrode active material layer 22a.

[0036] The negative electrode active material may be, for example, a carbon-based material, a silicon-based material, or a mixture thereof, but is not particularly limited thereto.

[0037] The negative electrode active material may be a coated negative electrode active material in which at least a portion of the surface thereof is coated with a coating material containing a polymer compound. When the periphery of the negative electrode active material is coated with the coating material, volume change of the negative electrode is alleviated, and expansion of the negative electrode can be suppressed.

[0038] As the coating material, the same coating material as that constituting the coated positive electrode active material can be suitably used.

[0039] The negative electrode active material layer 22b contains an electrolytic solution containing an electrolyte and a non-aqueous solvent. The composition of the electrolytic solution can be preferably the same as that of the electrolytic solution contained in the positive electrode active material layer 22a.

[0040] The negative electrode active material layer 22b may contain a conductive additive, which may suitably be the same conductive material as that contained in the positive electrode active material layer 22a.

[0041] The negative electrode active material layer 22b may contain an adhesive resin, which may be the same as the adhesive resin that is an optional component of the positive electrode active material layer 22a.

[0042] The thickness of the negative electrode active material layer 22b is not particularly limited, but from the viewpoint of battery performance, it is preferably 100 to 700 μm, and more preferably 200 to 500 μm.

[0043] In this embodiment, the negative electrode composition supplied to form the negative electrode active material layer 22b is a wet powder containing a negative electrode active material and a nonaqueous electrolyte. The wet powder is preferably in a pendular or funicular state. Alternatively, the negative electrode composition may be a clay-like (semi-solid) negative electrode active material kneaded with an electrolyte.

[0044] The proportion of the non-aqueous electrolyte in the wet powder is not particularly limited, but in order to achieve a pendular or funicular state, in the case of a negative electrode, it is desirable that the proportion of the non-aqueous electrolyte be 0.20 to 40% by weight of the entire wet powder.

[0045] <Examples of separators> Examples of the electrolyte held in the separator 30 include an electrolytic solution and a gel polymer electrolyte. The use of these electrolytes ensures high lithium ion conductivity in the separator 30. The form of the separator 30 is, for example, a porous film made of polyethylene or polypropylene, but is not particularly limited thereto.

[0046] <Example of frame body> The frame 35 is not particularly limited as long as it is a material that is durable against the electrolyte, but for example, a polymer material is preferred, and a thermoplastic polymer material is more preferred. The material constituting the frame 35 may be any material that has insulating properties, sealing properties (liquid-tightness), heat resistance at battery operating temperatures, electrolyte resistance, etc., and a resin material is preferably used. More specifically, the frame 35 may be made of, for example, a polyolefin resin, a polyurethane resin, or a polyvinylidene fluoride resin, with polyolefin resin being preferred because of its high durability and ease of handling.

[0047] <Battery electrode manufacturing equipment> Next, a battery electrode manufacturing apparatus and a battery electrode manufacturing method (hereinafter referred to as manufacturing method) according to this embodiment will be described. For example, in the battery electrode manufacturing apparatus and the battery electrode manufacturing method, a positive electrode 20a and a negative electrode 20b are first manufactured. The manufacturing methods of the positive electrode 20a and the negative electrode 20b differ mainly in the electrode active material contained in the electrode active material layer 22. Here, as a manufacturing method of the electrode 20, the manufacturing methods of the positive electrode 20a and the negative electrode 20b will be collectively described.

[0048] 2 is a schematic diagram of a battery electrode manufacturing apparatus 1000. For example, the battery electrode manufacturing apparatus 1000 includes a chamber 100, a conveying device 200, an inspection device 300, an electrode composition supplying device 400, and a pressing device 500.

[0049] The chamber 100 is a room whose interior can be maintained at a pressure lower than atmospheric pressure. The interior of the chamber 100 is reduced to a pressure lower than atmospheric pressure by a vacuum pump (not shown). Note that standard atmospheric pressure is approximately 1013 hPa (approximately 101 kPa).

[0050] For example, a current collector roll 21R is disposed outside the chamber 100, and a strip-shaped current collector 21B is pulled out from the current collector roll 21R and conveyed into the chamber 100 through a slit.

[0051] Hereinafter, the strip-shaped current collector 21B will also be referred to simply as current collector 21B. Current collector 21B is also called a current collector sheet. When current collector 21B is a resin current collector, it preferably contains a conductive filler and a matrix resin, as described above. Current collector 21B can be cut to a predetermined size to form current collector layer 21 shown in FIG. 1.

[0052] Within the chamber 100, the current collector 21B is transported at a predetermined speed by a transport device 200. The external space of the chamber 100 in which the current collector roll 21R is placed may be at normal pressure, or may be depressurized by a chamber different from the chamber 100.

[0053] In the following description, the transport direction in which current collector 21B is transported is referred to as the X direction, and the vertical direction is referred to as the Y direction. More specifically, the downstream side of the transport direction of current collector 21B corresponds to the +X direction, and the upstream side corresponds to the -X direction. Furthermore, the upper side in the vertical direction corresponds to the +Y direction, and the lower side corresponds to the -Y direction. When current collector 21B is transported horizontally, the X direction and the Y direction are perpendicular to each other. The Z direction, which is perpendicular to the X direction and the Y direction, corresponds to the width direction of current collector 21B.

[0054] The conveying device 200 conveys the current collector 21B in the +X direction. For example, the conveying device 200 is a belt conveyor that supports the current collector 21B from below. After the electrode composition 22c (described later) is supplied, the conveying device 200 conveys the current collector 21B carrying the electrode composition 22c. After the frame 35 (described later) is supplied, the conveying device 200 conveys the frame 35 and the current collector 21B carrying the electrode composition 22c.

[0055] Inspection device 300 is a device for evaluating uneven distribution of conductive filler in current collector 21 B. Details of inspection device 300 will be described later.

[0056] The electrode composition supplying device 400 is a device that supplies the electrode composition 22c to the current collector 21B conveyed by the conveying device 200. The specific configuration of the electrode composition supplying device 400 is not particularly limited, but as an example, it can be composed of a hopper and a shutter. That is, the electrode composition supplying device 400 holds the electrode composition 22c inside the hopper, and can apply the electrode composition 22c to a desired position on the current collector 21B by opening and closing the opening of the hopper with the shutter. Furthermore, part or all of the inner wall of the hopper may be composed of a moving belt, so that the electrode composition 22c inside the hopper can be moved.

[0057] The press device 500 compresses the electrode composition 22c supplied onto the current collector 21B. For example, the press device 500 has an upper roller 501 and a lower roller 502. The press device 500 sandwiches and compresses the electrode composition 22c supplied to the current collector 21B between the upper roller 501 and the lower roller 502. That is, the press device 500 performs roll pressing on the electrode composition 22c.

[0058] When performing the roll press, a release film may be used to prevent the electrode composition 22c from adhering to the roller. For example, a rolled release film is pulled out in synchronization with the conveyance speed of the electrode composition 22c and placed on top of the electrode composition 22c before the roll press. By performing the roll press with the release film sandwiched between the upper roller 501 and the electrode composition 22c, adhesion of the electrode composition 22c to the upper roller 501 is prevented. After the roll press, the release film is peeled off from the electrode composition 22c and can be recovered, for example, by being wound up in a roll.

[0059] The electrode composition supplying device 400 may also include a roller. Specifically, the electrode composition supplying device 400 applies the electrode composition 22c onto the current collector 21B by controlling a hopper and a shutter, and also smooths the surface of the applied electrode composition 22c with a roller. That is, the roller included in the electrode composition supplying device 400 is a smoothing roller that applies pressure to the extent that the surface of the electrode composition 22c is smoothed.

[0060] Alternatively, the rollers provided in the electrode composition supply device 400 may be compression rollers that compress the electrode composition 22c. In this case, the electrode composition 22c is compressed in two stages by the rollers provided in the electrode composition supply device 400 and the press device 500. Alternatively, the press device 500 may be omitted, and the electrode composition 22c may be compressed only by the rollers provided in the electrode composition supply device 400.

[0061] Although not shown in FIG. 2 , the battery electrode manufacturing apparatus 1000 may further include a frame supplying device. The frame supplying device supplies a frame 35 to the current collector 21B being transported. For example, the frame supplying device may have a robot arm and place a pre-manufactured frame 35 at a predetermined position on the current collector 21B being transported. Alternatively, the frame supplying device may manufacture the frame 35 on the current collector 21B. For example, the current collector 21B is used as a base material, and a predetermined material is ejected or applied in a predetermined shape onto the current collector 21B using a dispenser, a coater, or the like, to form the frame 35 on the current collector 21B.

[0062] As described above, the battery electrode manufacturing apparatus 1000 of Fig. 2 can manufacture electrodes such as the positive electrode 20a and the negative electrode 20b. Furthermore, the unit cell 10 can be manufactured by stacking the positive electrode 20a and the negative electrode 20b with the separator 30 sandwiched therebetween. The step of stacking the positive electrode 20a and the negative electrode 20b with the separator 30 sandwiched therebetween may be performed by the battery electrode manufacturing apparatus 1000, or may be performed by an apparatus different from the battery electrode manufacturing apparatus 1000.

[0063] For example, the battery electrode manufacturing apparatus 1000 manufactures the positive electrode 20a and the negative electrode 20b by performing the various steps described with reference to FIG. 2. Next, the battery electrode manufacturing apparatus 1000 supplies a separator 30 to the surface of the positive electrode 20a facing the positive electrode active material layer 22a, and then supplies the negative electrode 20b so that the separator 30 and the negative electrode active material layer 22b are in contact with each other, thereby manufacturing a single cell 10. Alternatively, the battery electrode manufacturing apparatus 1000 supplies a separator 30 to the surface of the negative electrode 20b facing the negative electrode active material layer 22b, and then supplies the positive electrode 20a so that the separator 30 and the positive electrode active material layer 22a are in contact with each other, thereby manufacturing a single cell 10. The separator 30 may be supplied continuously to the current collector 21B and the electrode composition 22c being transported along the transport direction (X direction), or may be supplied sheet by sheet after dividing the current collector 21B and the electrode composition 22c into predetermined units.

[0064] The above describes an example of the overall configuration of the battery electrode manufacturing apparatus 1000, including the inspection device 300. The quality of the electrode 20 manufactured by the battery electrode manufacturing apparatus 1000 is affected by various factors, one of which is the quality of the current collector 21B.

[0065] For example, while it is preferable that the conductive filler be uniformly dispersed within the current collector 21B, cases where the conductive filler distribution is uneven are conceivable. For example, in areas where the conductive filler is insufficient, the conductivity may be insufficient to function as the current collector layer 21 of the electrode 20. Furthermore, the current collector layer 21 of the electrode 20 also serves to encapsulate the electrode active material layer 22 containing the electrolyte solution, and there is a concern that liquid leakage may occur in areas where the conductive filler is excessively concentrated. Therefore, it is preferable not to use, in the manufacturing of the electrode 20, areas of the current collector 21B where the conductive filler is excessively concentrated or where the conductive filler is insufficient.

[0066] However, the conductive filler is also distributed inside the current collector 21B. Also, there are cases where there is almost no difference in color between the conductive filler and other parts of the current collector 21B. For these reasons, it is not easy to evaluate the uneven distribution of the conductive filler by visual inspection or optical camera images, etc.

[0067] Therefore, the inspection device 300 of the first embodiment makes it possible to evaluate the uneven distribution of the conductive filler in the current collector 21B by the process described below.

[0068] First, an example of the configuration of an inspection device 300 according to the first embodiment will be described with reference to Fig. 3. For example, the inspection device 300 includes a control device 310, an X-ray inspection device 320, and a thickness measurement device 330.

[0069] The control device 310 controls the operations of the X-ray inspection device 320 and the thickness measurement device 330, and executes a process for evaluating the uneven distribution of the conductive filler in the current collector 21B based on the outputs from the X-ray inspection device 320 and the thickness measurement device 330. The specific configuration of the control device 310 is not particularly limited, but as an example, the control device 310 includes a processing circuit such as a CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit), and the processing circuit executes a predetermined program to realize each process described below. The control device 310 is an example of a control unit.

[0070] The X-ray inspection device 320 is a device that performs X-ray inspection on the current collector 21B under the control of the control device 310. Specifically, the X-ray inspection device 320 includes an X-ray generator 321 and an X-ray detector 322. The X-ray generator 321 is, for example, an X-ray tube, and irradiates the current collector 21B with X-rays. The X-ray detector 322 is, for example, an X-ray flat panel detector (FPD), and detects X-rays that have passed through the current collector 21B. Alternatively, the X-ray detector 322 may be a line camera in which detection elements are arranged in the width direction (Z direction). Furthermore, the X-ray detector 322 may have a TDI (Time Delay Integration) function. The X-ray generator 321 is an example of a radiation generator. The X-ray detector 322 is an example of a radiation detector.

[0071] The thickness measuring device 330 is a device that measures the thickness of the current collector 21B. For example, the thickness measuring device 330 includes a sensor head 331 that can measure the distance to an object using a laser or the like. For example, the thickness measuring device 330 fixes the height of the lower surface of the current collector 21B by supporting the lower surface (the surface on the -Y direction side) of the current collector 21B with a fixed frame, a moving belt, or the like. Alternatively, in the case of roll-to-roll transport, the current collector 21B is supported by transport rolls. The thickness measuring device 330 can measure the distance from the upper surface to the lower surface of the current collector 21B (i.e., the thickness) by measuring the height of the upper surface (the surface on the +Y direction side) of the current collector 21B with the sensor head 331. Alternatively, the thickness measuring device 330 may measure the distance from the upper surface to the lower surface of the current collector 21B (i.e., the thickness) from both the upper and lower surfaces of the current collector 21B in the free portions between the supports. The thickness measuring device 330 may measure the entire current collector 21B in the width direction (Z direction), or may measure a portion of the current collector 21B in the width direction, measuring one or more specific fixed points, or measuring the entire width by a sampling method while traversing the sensor head 331 in the width direction. The thickness measuring device 330 is an example of a measuring unit.

[0072] An example configuration of the inspection device 300 has been described above. With this configuration, the inspection device 300 executes a process for evaluating the uneven distribution of the conductive filler in the current collector 21B. Specifically, the X-ray generator 321 in the inspection device 300 irradiates the current collector 21B with X-rays. The X-ray detector 322 detects the X-rays that have passed through the current collector 21B. The control device 310 evaluates the uneven distribution of the conductive filler in the current collector 21B based on the detection result of the X-rays by the X-ray detector 322.

[0073] For example, X-rays emitted from X-ray generator 321 pass through current collector 21B and are detected by each detection element of X-ray detector 322. X-ray detector 322 outputs a detection signal corresponding to the detected X-ray dose to control device 310, and control device 310 generates an X-ray image shown in Fig. 4A based on the detection signal. For example, control device 310 performs current-to-voltage conversion, A / D conversion, parallel-to-serial conversion, etc. on the detection signal received from X-ray detector 322 to generate the X-ray image.

[0074] Next, the control device 310 analyzes the X-ray image to evaluate the uneven distribution of the conductive filler. For example, the control device 310 obtains the density of the conductive filler at each position on the current collector 21B based on the X-ray image.

[0075] Specifically, the conductive filler has a larger X-ray absorption coefficient than other parts of the current collector 21B (such as the matrix resin), and absorbs more X-rays. Therefore, if the conductive filler is present on the X-ray path, the amount of X-ray detected by the detection element will be smaller, and the pixel value of the corresponding pixel in the X-ray image will be smaller. Furthermore, if there is a large amount of conductive filler on the X-ray path, more X-rays will be absorbed. Therefore, the control device 310 can evaluate the amount of conductive filler present at each position on the current collector 21B based on the pixel value of the X-ray image.

[0076] For example, the control device 310 evaluates the amount of conductive filler present in a stepless manner using the pixel value of each pixel in the X-ray image as is. For example, if the number of gradations of each pixel in the X-ray image is 10 bits, the evaluation will be based on pixel values ​​in 1024 steps, which is also included in the stepless evaluation.

[0077] As mentioned above, the pixel value of each pixel in an X-ray image varies depending on the extent of the conductive filler present along the X-ray path. More specifically, as the length of the conductive filler in the X-ray irradiation direction increases, the amount of X-ray absorption increases, and the amount of X-rays reaching the pixel decreases, resulting in a decrease in the pixel value. In the following description, the length of the conductive filler in the X-ray irradiation direction will also be referred to as the filler length. In other words, the smaller the pixel value, the larger the filler length and the greater the amount of conductive filler present.

[0078] Furthermore, the pixel value may also be affected by the area of ​​the conductive filler, which is the area of ​​the conductive filler as viewed from the X-ray irradiation direction, and will hereinafter be referred to simply as the filler area.

[0079] When the filler area is larger than the pixel area and the entire pixel corresponds to the conductive filler, the pixel value is a value corresponding to the filler length. Of course, when there are multiple conductive fillers on the X-ray path, the pixel value is a value corresponding to the sum of the filler lengths of the multiple conductive fillers.

[0080] On the other hand, if the filler area is smaller than the pixel area, or even if the filler area is larger than the pixel area, only a portion of one pixel will correspond to the conductive filler at the filler outline. In this case, the pixel value will be a value affected not only by the filler length but also by the filler area. Specifically, the larger the proportion of the filler area to the pixel area, the more X-rays are absorbed, and the smaller the pixel value. Of course, when multiple conductive fillers are present, the pixel value will be a value corresponding to the sum of the filler areas of the multiple conductive fillers.

[0081] When the filler area is larger than the pixel area and the entire pixel corresponds to the conductive filler, it is possible to estimate the filler length based on the pixel value. On the other hand, when the filler area is smaller than the pixel area, it is not possible to estimate the filler length based on the pixel value. This is because it is not possible to determine the percentage of the pixel value that the filler area and filler length contribute to. However, both the filler area and filler length indicate the amount of conductive filler present, and the amount of conductive filler present can be evaluated without having to distinguish between them. In other words, whether the entire pixel corresponds to the conductive filler or only a partial region of the pixel corresponds to the conductive filler, the amount of conductive filler present can be evaluated using the pixel value of each pixel in the X-ray image.

[0082] For example, the control device 310 divides the X-ray image into multiple sections as shown in Fig. 4B. Each section in Fig. 4B includes multiple pixels of the X-ray image. In this case, the control device 310 can obtain the density of the conductive filler for each section by calculating statistics (such as the average, median, or sum) of the pixel values ​​within the section.

[0083] The process shown in FIG. 4B is an example of binning. Hereinafter, a binned image will also be referred to as a binned image. Binning is a process of bundling signals collected by multiple detection elements in the X-ray detector 322 into a single signal. Binning may be performed on the X-ray image as shown in FIG. 4B (soft binning), or on the detection signals used to generate the X-ray image (hard binning). For example, the X-ray detector 322 performs bundling on the detection signals detected by the multiple detection elements, and the control device 310 generates a binned image based on the detection signals after bundling. Of course, soft binning may be performed after hard binning.

[0084] It is also possible to use an X-ray image in which a pixel is assigned to each detection element as is. This is because each pixel in such an X-ray image also indicates the density of the conductive filler within the area corresponding to each pixel. However, although the resolution is reduced in a binned image, the influence of noise is mitigated. Because the detection value of the X-ray detector 322 contains noise that causes measurement variation, it is preferable to obtain the density of the conductive filler based on a binned image so as to obtain the required detection accuracy. In the following description, unless there is a particular distinction between a binned image and an X-ray image generated without binning, they will simply be referred to as an X-ray image.

[0085] Because the greater the thickness, the greater the amount of conductive filler present, it is insufficient to evaluate the uneven distribution of conductive filler based solely on the density of the conductive filler described above. For example, even if the density shows a high value, it may be that the cause is not uneven distribution of conductive filler but an increase in the thickness of current collector 21B. Therefore, control device 310 evaluates the uneven distribution of conductive filler based on the X-ray detection results by X-ray inspection device 320 and the measurement results of the thickness of current collector 21B by thickness measurement device 330.

[0086] For example, the control device 310 compares the thickness measurement results and the density of the conductive filler with standards. Specifically, the control device 310 sets a threshold value for the thickness of the current collector 21B, and determines that any portion exceeding an upper threshold or any portion below a lower threshold does not meet the standard. Furthermore, the control device 310 also sets a threshold value for the density of the conductive filler, and determines that any portion exceeding an upper threshold or any portion below a lower threshold does not meet the standard. Since the density of the conductive filler can be evaluated after clarifying whether the thickness standard is met, it becomes possible to more appropriately evaluate the unevenness of the conductive filler.

[0087] 3 illustrates a single control device 310, the control device 310 may be realized by combining multiple devices. For example, a control device 310 that performs a process of comparing the thickness measurement result with a standard and a control device 310 that performs a process of comparing the density of the conductive filler with a standard may each be provided as separate devices. In addition, the various processes performed by the control device 310 may be distributed and executed by multiple devices, or may be integrated and executed by a single device.

[0088] As another example, the control device 310 performs a correction process (calibration) on the acquired density of the conductive filler in accordance with the measurement result of the thickness of the current collector 21B by the thickness measuring device 330.

[0089] Specifically, in the thicker portion of current collector 21B, a larger amount of conductive filler is distributed and absorbs more X-rays, so the above-described process calculates a larger value for the conductive filler density. However, considering the three-dimensional space including the depth direction (Y direction), the fact that a larger amount of conductive filler is distributed in the thicker portion does not necessarily mean that the density is higher. Therefore, control device 310 performs a correction process to reduce the acquired conductive filler density when current collector 21B is thick, and to increase it when current collector 21B is thin.

[0090] Then, the control device 310 evaluates the unevenness of the conductive filler based on the corrected density of the conductive filler. For example, the control device 310 sets a threshold value for the corrected density, and determines that a portion exceeding an upper threshold or a portion below a lower threshold does not meet the standard. This allows the density of the conductive filler to be evaluated after eliminating the influence of the thickness of the current collector 21B, making it possible to more appropriately evaluate the unevenness of the conductive filler.

[0091] As described above, the inspection device 300 can appropriately evaluate the uneven distribution of the conductive filler, thereby improving the quality of the manufactured electrode 20. For example, a portion determined to be non-conforming to the standard can be excluded from the manufacturing process. As one example, the electrode composition supply device 400 can supply the electrode composition 22c while avoiding the portion of the current collector 21B determined to be non-conforming to the standard.

[0092] Alternatively, the current collector 21B may be separated into sheets, and then the portion determined to be non-conforming to the standard may be removed. Specifically, the electrode composition 22c supplied onto the current collector 21B is compressed by a press device 500, and the current collector 21B is cut into sheets of a predetermined size, thereby manufacturing the positive electrode 20a and the negative electrode 20b shown in FIG. 1. That is, the current collector 21B is separated into sheets after the step shown in FIG. 2. Then, after separating the current collector 21B into sheets, those containing the portion determined to be non-conforming to the standard may be selectively removed.

[0093] (Second embodiment) In the above-described first embodiment, an example has been described in which the unevenness of the conductive filler is evaluated by obtaining the density of the conductive filler at each position on the current collector 21B. In contrast, in the second embodiment, an example will be described in which the unevenness of the conductive filler is evaluated by obtaining the magnitude of variation in the detection results.

[0094] The control device 310 compares the X-ray detection results between pixels to determine the magnitude of variation in the detection results. The control device 310 then compares the magnitude of variation in the detection results with a threshold value. Any areas outside the threshold are deemed to be areas of uneven distribution of conductive filler and are therefore excluded from the manufacturing process. For example, the control device 310 calculates the distribution of pixel values ​​for each predetermined area. The predetermined area may be, for example, the surface size when assembled into a battery. Alternatively, it may be the entire current collector 21B. Any areas of the calculated pixel value distribution that exceed a predetermined threshold are deemed to be areas where the filler is insufficiently dispersed and are therefore excluded from the manufacturing process. The threshold value is determined, for example, as n times the standard deviation. The exclusion may be limited to a minimum range near the area exceeding the threshold, or may be based on the dimensions of the area to be assembled into a battery. Outliers on the small pixel value side are considered to be localized due to the aggregation of conductive filler, while outliers on the large pixel value side are presumed to be areas where the conductive filler is sparse. Such areas are deemed defective and are therefore excluded from the manufacturing process.

[0095] In the calculation, one pixel value may not only be treated as one piece of data, but also may be subjected to the binning described in the first embodiment. Since the detected value of the X-ray detector 322 contains noise that causes measurement variations, it is preferable to set the binning size to a size that can obtain the required detection accuracy.

[0096] It is known that the X-ray dose of an X-ray source decreases over time. Furthermore, as the cumulative amount of received light increases, the detection capability of an X-ray camera gradually declines due to browning and other factors. For these reasons, the accuracy of X-ray camera measurements cannot always be maintained at the calibration stage. Therefore, using a specific fixed threshold can lead to erroneous judgments. However, the method for evaluating variation in the second embodiment makes it possible to identify areas where conductive filler imbalance has occurred without being affected by changes in the performance of the X-ray source and X-ray camera. On the other hand, performance changes can also be addressed by performing corrections. However, because the current collector 21B is transported roll-to-roll, there is always a workpiece being transported at the X-ray inspection station. Therefore, corrections are difficult because the presence of this workpiece interferes with the calibration process. This requires costly and time-consuming measures, such as providing a mechanical mechanism for recalibration in areas without workpieces or periodically cutting the path line and reconnecting it after calibration. The technology of the present invention can easily address this issue.

[0097] When evaluating the uneven distribution of conductive filler particles based on the magnitude of variation, as in the second embodiment, real-time judgment is not possible unless the calculation capacity is sufficient. Attempting to secure such capacity inevitably increases the introduction cost of the control device 310. Therefore, the calculation of the pixel value distribution may be performed when one current collector roll 21R is used up. Alternatively, judgment may be performed by setting a predetermined threshold value as master data based on past data. However, it is desirable to update this master data as needed, taking into account the deviation of the X-ray measurement values ​​from the true value over time. In this way, real-time judgment can be performed at low cost.

[0098] (Third embodiment) In the third embodiment, an example of evaluating the uneven distribution of conductive filler by evaluating lumps of conductive filler will be described. The process described in the third embodiment may be performed in addition to or instead of the process of evaluating the uneven distribution of conductive filler described in the first and second embodiments.

[0099] The control device 310 of the third embodiment evaluates the conductive filler agglomerates based on the X-ray detection results. For example, the control device 310 measures the size of each conductive filler agglomerate depicted in the X-ray image. As an example, the control device 310 measures the size of the conductive filler agglomerate by measuring the area and perimeter of the agglomerate, the length of the longest line segment (major axis) that can be set inside the agglomerate, and so on. Then, the control device 310 removes conductive filler agglomerates with a size exceeding a threshold value from the manufacturing process as areas where conductive filler has become uneven.

[0100] The control device 310 may evaluate the properties of the conductive filler agglomerates in addition to their sizes. An example of evaluating the properties of the conductive filler agglomerates will be described below with reference to Figures 5A and 5B.

[0101] 5A and 5B are conceptual diagrams assuming that the X-ray image of Fig. 4A is viewed from the width direction (Z direction). In the X-ray image of Fig. 4A, a large particle of conductive filler is depicted in the center, but the conductive filler may be one large mass as shown in Fig. 5A, or may be a collection of small masses as shown in Fig. 5B.

[0102] If the conductive filler exists as one large mass, the electrolyte moves along the interface of the conductive filler, increasing the risk of leakage. Furthermore, stress concentration is likely to occur, which may lead to damage to the current collector 21B. In contrast, in the case of a collection of small masses, the interface of the conductive filler is discontinuous, as shown in FIG. 5B. In other words, in the case of a collection of small masses, the path for leakage is complex, making leakage less likely to occur. In other words, compared to a single large mass, a collection of small masses is less likely to lead to leakage and is less likely to cause stress concentration.

[0103] Thus, even if the conductive filler particles are depicted as being of approximately the same size on an X-ray image, the effect on the quality of current collector 21B varies depending on their properties, such as whether they are one large lump or a collection of small lump. Therefore, control device 310 evaluates the properties of the conductive filler particles in addition to their size, and evaluates the unevenness of the conductive filler particles.

[0104] For example, if the conductive filler agglomerate being evaluated is a collection of small agglomerates, the amount of X-ray absorption will be less than if it were a single large agglomerate, and the amount of X-ray absorption will vary from position to position. That is, if the conductive filler agglomerate appearing in the X-ray image is a collection of small agglomerates, the pixel value will be larger than if it were a single large agglomerate, and there will be variations in shading within the agglomerate. Based on these characteristics, the control device 310 can determine whether the conductive filler agglomerate appearing in the X-ray image is a single large agglomerate or a collection of small agglomerates.

[0105] (Fourth embodiment) 2, the inspection device 300 has been described as part of the configuration of the battery electrode manufacturing device 1000. That is, an example has been described in which a process for evaluating unevenness of the conductive filler is performed during the process of manufacturing the electrode 20. However, the embodiment is not limited to this. For example, when manufacturing the strip-shaped current collector 21B, a process for evaluating unevenness of the conductive filler may be performed before the current collector film is wound into a roll.

[0106] The aforementioned process for evaluating the uneven distribution of conductive filler can also detect structural defects such as pinholes, cavities, cracks, and wrinkles. For example, defects on the surface of current collector 21B are detected as abnormal values ​​in thickness measurements using thickness measurement device 330. Defects in current collector 21B, whether on the surface or inside, appear as shadows on X-ray images and can be detected using image processing such as pattern matching. It is preferable to eliminate portions in which structural defects are detected from the manufacturing process of electrode 20. The defect detection process using inspection device 300 may be performed using artificial intelligence (AI). For example, a machine learning model capable of detecting defects based on image input is generated in advance, and inspection device 300 detects defects such as cavities by inputting X-ray images into the machine learning model. Minor cavities may be tolerated, and the relationship between the cavities and the inspection results in subsequent processes may be studied to determine whether the product is good. Specific examples of machine learning models are not particularly limited, and any classifier or discriminator, such as a neural network, support vector machine, or random forest, may be used.

[0107] There are various factors that cause structural defects in current collector 21B, and defects may occur when strip-shaped current collector 21B is wound up to manufacture current collector roll 21R, when current collector 21B is pulled out from current collector roll 21R, or when current collector 21B is transported into chamber 100. As shown in Fig. 2, by performing a process to evaluate the unevenness of the conductive filler on current collector 21B that has been pulled out from current collector roll 21R and transported into chamber 100 immediately before use, structural defects in current collector 21B that occur due to various factors can be efficiently inspected.

[0108] (Fifth embodiment) The above-described embodiment is merely an example, and various modifications are possible.

[0109] For example, in the above-described embodiment, an example has been described in which an X-ray image is generated based on a detection signal received from the X-ray detector 322, and the bias of the conductive filler is evaluated based on the X-ray image. However, the embodiment is not limited to this.

[0110] For example, the control device 310 may evaluate the bias of the conductive filler based on the detection signal received from the X-ray detector 322 or the detection signal after any processing has been performed, without performing processing to generate an X-ray image. That is, the control device 310 can evaluate the bias and structural defects of the conductive filler in the current collector 21B based on the detection result of the X-rays by the X-ray detector 322, regardless of whether it has been converted into image data format.

[0111] In addition, the above description has been given of an example in which the uneven distribution of conductive filler is evaluated and the portion where uneven distribution of conductive filler occurs is removed from the manufacturing process. However, various modifications can be made to the method of utilizing the evaluation results of uneven distribution of conductive filler. For example, the control device 310 may notify the user of the evaluation results of uneven distribution of conductive filler by displaying them on a display or the like.

[0112] For example, when the uneven distribution of the conductive filler is greater than a standard, the control device 310 notifies the user. The user who has received such a notification can take measures to reduce the uneven distribution of the conductive filler in the current collector 21B, such as changing the conditions when manufacturing the current collector 21B, or changing the current collector roll 21R to a different roll when manufacturing a battery using an already manufactured current collector roll.

[0113] Although X-rays have been described as an example of radiation, inspections may be performed using other types of radiation. For example, a gamma ray inspection device or a beta ray inspection device may be provided instead of the X-ray inspection device 320 described above.

[0114] 2 illustrates an example in which a process for evaluating unevenness of the conductive filler is performed on current collector 21B that has been pulled out from current collector roll 21R and transported into chamber 100. However, the embodiment is not limited to this. For example, inspection device 300 may be disposed outside chamber 100, and a process for evaluating unevenness of the conductive filler may be performed on current collector 21B that has been pulled out from current collector roll 21R.

[0115] In addition, an example in which the electrode composition 22c is supplied to the strip-shaped current collector 21B by the electrode composition supply device 400 has been described above. However, the embodiment is not limited to this. For example, the strip-shaped current collector 21B shown in FIG. 2 may be replaced with a strip-shaped separator sheet, and the electrode composition 22c may be supplied to the separator sheet. The strip-shaped separator sheet can be subsequently trimmed to form the separator 30 shown in FIG. 1. For example, the strip-shaped current collector 21B shown in FIG. 2 may be replaced with a strip-shaped release film, and the electrode composition 22c may be supplied to the release film. The current collector 21B, the separator sheet, and the release film are collectively referred to as the substrate film. In other words, the substrate film is the film to which the electrode composition 22c is supplied.

[0116] For example, when a separator sheet is used as the base film, positive electrode 20a or negative electrode 20b can be produced by supplying electrode composition 22c onto the separator sheet, supplying frame 35 on the separator sheet in a position surrounding electrode composition 22c, supplying current collector 21B to the surface of electrode composition 22c opposite the separator sheet, and trimming the separator sheet and current collector 21B to a predetermined shape. When supplying current collector 21B to the surface of electrode composition 22c opposite the separator sheet, inspection can be performed on current collector 21B using inspection device 300 described above.

[0117] Furthermore, when a release film is used as the substrate film, the electrode composition 22c is supplied onto the release film, a frame 35 is supplied on the release film in a position surrounding the electrode composition 22c, a current collector 21B is supplied to the surface of the electrode composition 22c opposite the release film, the release film is removed, and then a separator sheet is supplied to the surface opposite the current collector 21B. The current collector 21B and the separator sheet are trimmed to a predetermined shape, thereby producing the positive electrode 20a or the negative electrode 20b. Note that instead of supplying a separator sheet and then trimming, a separator 30 trimmed to a specific shape may be supplied to the electrode composition 22c. When the current collector 21B is supplied to the surface of the electrode composition 22c opposite the release film, the current collector 21B can be inspected using the inspection device 300 described above.

[0118] Alternatively, the electrode composition 22c is supplied onto a release film, a frame 35 is supplied onto the release film in a position surrounding the electrode composition 22c, a separator sheet is supplied onto the surface of the electrode composition 22c opposite the release film, the release film is removed, and then a current collector 21B is supplied onto the surface opposite the separator sheet. The separator sheet and the current collector 21B are trimmed to a predetermined shape, thereby producing the positive electrode 20a or the negative electrode 20b. Note that instead of supplying the current collector 21B and then trimming it, the current collector 21B trimmed to a predetermined shape may be supplied to the electrode composition 22c. When supplying the current collector 21B onto the surface opposite the separator sheet, the current collector 21B can be inspected using the inspection device 300 described above.

[0119] Although the above description has been given of an example in which the electrode composition 22c is supplied by a predetermined length at a time by repeatedly starting and stopping the supply of the electrode composition 22c to the base film, the present invention is not limited to this example. That is, the electrode composition 22c may be supplied to the base film continuously.

[0120] For example, a sheet of electrode composition 22c alone can be produced by continuously supplying electrode composition 22c onto a release film as a base film, compressing the film, and then peeling off electrode composition 22c from the release film. The sheet of electrode composition 22c alone can then be trimmed to a predetermined size and combined with frame 35, current collector 21B (or a sheet of current collector 21B), and separator 30 (or a sheet of separator 30), to produce positive electrode 20a or negative electrode 20b. The order in which frame 35, current collector 21B (or a sheet of current collector 21B), and separator 30 (or a sheet of separator 30) are supplied to trimmed electrode composition 22c can be arbitrary. When supplying current collector 21B to trimmed electrode composition 22c, inspection of current collector 21B can be performed using inspection device 300 described above.

[0121] Furthermore, in an embodiment in which a release film is used as the substrate film, the electrode composition 22c may be cut to a predetermined size together with the release film, rather than peeling off the release film to obtain a sheet of the electrode composition 22c alone and then trimming it to a predetermined size. When the electrode composition 22c has release films on both sides, one of the release films may be continuously peeled off and then cut. After removing the release film cut together with the electrodes, the cut electrode composition 22c can be combined with the current collector 21B or a sheet thereof, the frame 35, and the separator 30 or a sheet thereof to produce the positive electrode 20a and the negative electrode 20b. The release film may be removed at any time. As described above, the frame 35 may be formed directly on the current collector 21B or a sheet of the current collector 21B by a discharge method or a coating method. When the current collector 21B is supplied to the electrode composition 22c or when the current collector 21B is separated into sheets, the current collector 21B can be inspected by the inspection device 300 described above.

[0122] Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configurations are not limited to these embodiments, and modifications, combinations, deletions, etc. of the configurations are also included within the scope of the gist of the present invention. Furthermore, it goes without saying that the configurations shown in each embodiment can be appropriately combined and used. When using the lithium-ion secondary battery exemplified above, the secondary battery includes a battery using a liquid material for the electrolyte and a battery using a solid material for the electrolyte (so-called all-solid-state battery). Furthermore, the battery in this embodiment includes a battery having a metal foil (metal current collector foil) as a current collector, and a battery having a so-called resin current collector made of a resin to which a conductive material has been added instead of the metal foil. [Explanation of symbols]

[0123] 10: Single cell 20: Electrode 20a: Positive electrode 20b: Negative electrode 21: Current collector layer 21B: Current collector 21a: Positive electrode current collector layer 21b: Negative electrode current collector layer 21R: Current collector roll 22: Electrode active material layer 22a: Positive electrode active material layer 22b: Negative electrode active material layer 22c: Electrode composition 30: Separator 35:Frame body 100: Chamber 200:Transportation device 300: Inspection equipment 310: Control device 320: X-ray inspection equipment 321: X-ray generator 322: X-ray detector 330: Thickness measuring device 400: Electrode composition supply device 500: Press equipment 501: Upper roller 502: Lower roller 1000:Battery electrode manufacturing equipment

Claims

1. a radiation generator that irradiates a strip-shaped resin current collector containing a conductive filler with radiation; a radiation detector that detects the radiation that has passed through the resin current collector; a measuring unit for measuring the thickness of the resin current collector; a control unit that evaluates the unevenness of the conductive filler in the resin current collector based on the radiation detection result and the thickness measurement result; An inspection device comprising:

2. The inspection device according to claim 1 , wherein the control unit evaluates unevenness of the conductive filler by obtaining the density of the conductive filler at each position on the resin current collector based on the detection result.

3. The inspection device according to claim 1 , wherein the control unit evaluates the unevenness of the conductive filler by acquiring the magnitude of the variation in the detection results.

4. The inspection device according to claim 1 , wherein the control unit evaluates the unevenness of the conductive filler by evaluating the clumps of the conductive filler based on the detection result.

5. A radiation generator is used to irradiate a strip-shaped resin current collector containing a conductive filler with radiation; detecting the radiation that has passed through the resin current collector with a radiation detector; Measure the thickness of the resin current collector; Based on the radiation detection results and the thickness measurement results, the unevenness of the conductive filler in the resin current collector is evaluated. An inspection method comprising:

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