Impurity treatment device and impurity treatment method

Abstract

An impurity processing device comprising piping that channels a metal-impurity-containing liquid subject to processing, a first electrode and a second electrode that are positioned in the piping, and a power supply unit for channeling a current between the first electrode and the second electrode.

Description

[Technical field]

[0001] The present disclosure relates to an impurity treatment device and an impurity treatment method. [Background technology]

[0002] When preparing a solid-liquid mixture having electronic conductivity, metal particles may be mixed in as impurities. When this solid-liquid mixture is used in an electronic device, the impurities may cause defects in the electronic device. For example, examples of electronic devices include electric storage devices such as lithium ion batteries, lithium ion secondary batteries, alkaline dry batteries, electric double layer capacitors, and electrochemical capacitors. Examples of solid-liquid mixtures include electrode slurries used in these electric storage devices. When metal impurities are mixed into the electrode slurry, the metal impurities may cause a short circuit between the positive and negative electrodes. In response to this, for example, Patent Document 1 discloses a method of magnetically removing metal foreign matter contained in an aqueous slurry containing an electrode active material and a particulate binder. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2014 / 142045 Summary of the Invention

[0004] Conventional methods that use magnetism to remove metallic impurities are unable to remove impurities made of non-magnetic metals, and therefore have an insufficient rate of impurity treatment.

[0005] One aspect of the present disclosure is an impurity treatment device that includes a pipe through which a liquid to be treated containing metal impurities flows, a first electrode and a second electrode disposed in the pipe, and a power supply unit that applies a current between the first electrode and the second electrode.

[0006] Another aspect of the present disclosure is a method for treating impurities, comprising: passing a liquid to be treated that contains metal impurities through a pipe;

[0007] Any combination of the above components and any conversion of the expression of the present disclosure between a method, an apparatus, a system, etc. are also valid as aspects of the present disclosure. Effect of the Invention

[0008] According to the present disclosure, it is possible to increase the treatment rate of impurities in the liquid to be treated. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a coating device provided with an impurity treatment device according to the first embodiment. [Figure 2A] FIG. 2A is a perspective view illustrating a schematic view of an electrode portion. [Figure 2B] FIG. 2B is a perspective view illustrating a schematic view of an electrode portion. [Figure 2C] FIG. 2C is a perspective view illustrating a schematic view of an electrode portion. [Figure 3A] FIG. 3A is a schematic diagram of an electrode unit included in the impurity treatment apparatus according to the second embodiment. [Figure 3B] FIG. 3B is a schematic diagram of an electrode unit included in the impurity treatment apparatus according to the second embodiment. [Figure 3C] FIG. 3C is a schematic diagram of an electrode unit included in the impurity treatment apparatus according to the second embodiment. [Figure 3D] FIG. 3D is a schematic diagram of an electrode unit included in the impurity treatment apparatus according to the second embodiment. [Figure 3E] FIG. 3E is a schematic diagram of an electrode unit included in the impurity treatment apparatus according to the second embodiment. [Figure 3F] FIG. 3F is a schematic diagram of an electrode unit included in the impurity treatment apparatus according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present disclosure will be described below with reference to the drawings based on preferred embodiments. The embodiments are illustrative and do not limit the present disclosure, and all features and combinations thereof described in the embodiments are not necessarily essential to the present disclosure. The same or equivalent components, members, and processes shown in each drawing are given the same reference numerals, and duplicated descriptions are omitted as appropriate. In addition, the scale and shape of each part shown in each drawing are set for convenience to facilitate explanation, and are not to be interpreted as being limiting unless otherwise specified. In addition, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, these terms do not represent any order or importance, but are intended to distinguish one configuration from another. In addition, some of the members that are not important in explaining the embodiment in each drawing are omitted.

[0011] (Embodiment 1) 1 is a schematic diagram of a coating apparatus provided with an impurity treatment device according to embodiment 1. The coating apparatus 1 includes a coating die 2, a valve 4, a tank 6, a pump 8, a feed pipe 10, a return pipe 12, and a die supply pipe 14.

[0012] The coating die 2 is a tool for applying the coating material 18 to the workpiece 16. The coating device 1 of this embodiment is used, as an example, to manufacture an electrode plate for a secondary battery. The electrode plate for a secondary battery is a sheet-shaped electrode material obtained by applying an electrode slurry to a current collector and drying it. Therefore, in this embodiment, the workpiece 16 is a current collector for a secondary battery, and the coating material 18 is an electrode slurry for a secondary battery. The current collector is, for example, a metal foil. The electrode slurry is an electronically conductive solid-liquid mixture containing a solvent and an electrode active material. Alternatively, the electrode slurry is a solid-liquid mixture containing a solvent and a conductive assistant. In the case of a general lithium-ion secondary battery, the electrode plate for the positive electrode is prepared by applying an electrode slurry containing a positive electrode active material such as lithium cobalt oxide or lithium iron phosphate to an aluminum foil. The positive electrode slurry may contain a conductive assistant such as graphite. The negative electrode plate is prepared by applying an electrode slurry containing a negative electrode active material (or a conductive assistant) such as graphite onto a copper foil.

[0013] The coating die 2 is disposed so that the discharge port 22 faces the peripheral surface of the backup roll 20 at a predetermined distance. The workpiece 16 is continuously transported by the rotation of the backup roll 20 to a position where the backup roll 20 and the discharge port 22 face each other.

[0014] A valve 4 is connected to the coating die 2 via a die supply pipe 14. The valve 4 can switch between supplying and not supplying paint 18 to the coating die 2. The coating device 1 can discharge paint 18 from the coating die 2 to a workpiece 16 while the paint 18 is being supplied to the coating die 2. A tank 6 is connected to the valve 4 via a feed pipe 10 and a return pipe 12.

[0015] The tank 6 stores the paint 18. A pump 8 is provided in the feed pipe 10, and the paint 18 is fed from the tank 6 to the valve 4 by driving the pump 8. The valve 4 supplies the paint 18 supplied from the tank 6 to the coating die 2 via a die supply pipe 14. Alternatively, the valve 4 returns the paint 18 supplied from the tank 6 to the tank 6 via a return pipe 12.

[0016] The valve 4 supplies the paint 18 to the coating die 2, so that the paint 18 can be discharged from the coating die 2 to form a coated portion 18a of the paint 18 on the workpiece 16. The valve 4 also returns the paint 18 to the tank 6, so that application of the paint 18 from the coating die 2 can be stopped and an uncoated portion 16a of the paint 18 can be formed on the workpiece 16. In other words, the valve 4 allows the paint 18 to be intermittently coated on the workpiece 16. The uncoated portion 16a is used for attaching a center lead of an electrode, etc. The configuration of each part of the coating device 1 is not limited to that described above.

[0017] The coating device 1 is provided with an impurity treatment device 100 according to this embodiment. The impurity treatment device 100 includes a pipe 102, an electrode unit 104, and a power supply unit 106. The pipe 102 is a flow path through which the liquid to be treated containing metal impurities flows. In this embodiment, the region of the feed pipe 10 between the tank 6 and the pump 8 constitutes the pipe 102. That is, the impurity treatment device 100 is provided in the feed pipe 10. Also, the paint 18, in other words, an electrode slurry containing a solvent and an electrode active material and / or a conductive assistant, corresponds to the liquid to be treated.

[0018] The impurity treatment device 100 may be provided in a region between the pump 8 and the valve 4 in the feed pipe 10. The impurity treatment device 100 may also be provided in the return pipe 12, the die supply pipe 14, or the like. The coating device 1 is not limited to use for manufacturing electrode plates for secondary batteries, and the body 16 to be coated and the coating material 18 do not have to be an electrode plate and an electrode slurry. The impurity treatment device 100 may also be provided in a device other than the coating device 1, for example, a device for manufacturing the liquid to be treated.

[0019] The electrode unit 104 includes a first electrode 108 and a second electrode 110. FIGS. 2A to 2C are perspective views that show the electrode unit 104 in a schematic manner. FIG. 2A is a first example of the electrode unit 104, FIG. 2B is a second example of the electrode unit 104, and FIG. 2C is a third example of the electrode unit 104. The first electrode 108 and the second electrode 110 are disposed in the pipe 102. The electrode unit 104 of the present embodiment has a rod-shaped body 112 that is inserted into the pipe 102. The first electrode 108 is provided in the pipe 102, and the second electrode 110 is provided in the rod-shaped body 112. The first electrode 108 and the second electrode 110 are insulated from each other.

[0020] The first electrode 108 and the second electrode 110 are made of a material having electrical conductivity. The material has, for example, a volume resistivity of 0.1 Ω·cm or less. Specific examples of materials that make up the first electrode 108 and the second electrode 110 include insoluble metals such as stainless steel, titanium, platinum, gold, niobium, and ruthenium, and carbon. These materials can also be combined as appropriate.

[0021] The first electrode 108 is provided at least on the inner wall (inner circumferential surface) of the pipe 102. The first electrode 108 may be provided on the entire inner wall of the pipe 102, or may be provided on a part of it. When the first electrode 108 is provided on a part of the inner wall, it may be a part of the area in the flow direction of the liquid to be treated, or may be a part of the area in the circumferential direction of the pipe 102. Furthermore, the entire pipe 102 may be made of an insoluble metal or the like, and the entire pipe 102 may constitute the first electrode 108. In other words, the first electrode 108 may be provided only on the surface of the inner wall of the pipe 102, or may be provided up to the inside of the inner wall.

[0022] The second electrode 110 is provided at least on the outer wall (peripheral surface) of the rod-shaped body 112. The second electrode 110 may be provided on the entire outer wall of the rod-shaped body 112, or on a part of it. When the second electrode 110 is provided on a part of the outer wall, it may be a part of the area in the flow direction of the liquid to be treated, or a part of the area in the circumferential direction of the rod-shaped body 112. Furthermore, the entire rod-shaped body 112 may be made of an insoluble metal or the like, and the entire rod-shaped body 112 may constitute the second electrode 110. In other words, the second electrode 110 may be provided only on the surface of the outer wall of the rod-shaped body 112, or may be provided up to the inside of the outer wall.

[0023] In a first example shown in FIG. 2A, the rod-shaped body 112 is hollow. The inside of the rod-shaped body 112 is sealed, and the liquid to be treated does not flow. In a second example shown in FIG. 2B, the rod-shaped body 112 is solid. By using a hollow or solid rod-shaped body 112 as the second electrode 110, it is possible to suppress an increase in pressure loss caused by the second electrode 110 when the liquid to be treated passes through the pipe 102. On the other hand, in a third example shown in FIG. 2C, the rod-shaped body 112 is a cylindrical mesh. The liquid to be treated can move between the inside and outside of the rod-shaped body 112 through the openings of the mesh while flowing through the pipe 102. By using a cylindrical mesh rod-shaped body 112 as the second electrode 110, it is possible to increase the contact area between the second electrode 110 and the liquid to be treated, thereby increasing the treatment rate of impurities by the impurity treatment device 100.

[0024] The power supply unit 106 passes a current between the first electrode 108 and the second electrode 110. The power supply unit 106 can be configured with a known DC / DC converter, a DC / AC inverter, or the like. For example, the first electrode 108 is connected to a positive output terminal of the power supply unit 106, and the second electrode 110 is connected to a negative output terminal of the power supply unit 106. Therefore, the first electrode 108 is a positive electrode, and the second electrode 110 is a negative electrode. The first electrode 108 may be a negative electrode, and the second electrode 110 may be a positive electrode. The current passed by the power supply unit 106 may be a direct current or an alternating current. The amount of current passed by the power supply unit 106 is, for example, 0.1 mA or more and 12 mA or less.

[0025] By applying a voltage from the power supply unit 106 to the first electrode 108 and the second electrode 110 and passing a current through the liquid to be treated to generate an electric field in the pipe 102, the metal impurities in the liquid to be treated can be ionized and miniaturized. Some of the metal impurities contained in the electrode slurry are as large as several hundred μm, but they can be miniaturized to a size of 10 μm or less by passing a current through the liquid to be treated. The inventors have confirmed that when a current is passed through the liquid to be treated that contains a copper wire as a metal impurity model, the mass of the copper wire decreases linearly with an increase in the amount of electricity, that is, the metal impurities are miniaturized. They have also confirmed that metal impurities can be miniaturized by passing either a direct current or an alternating current.

[0026] Moreover, by generating an electric field in the pipe 102 by the power supply unit 106, the metal impurities can be ionized and electrodeposited onto the surface of the first electrode 108 or the second electrode 110. This makes it possible to remove the metal impurities from the liquid to be treated. Note that a direct current is more suitable for micronizing the metal impurities, while an alternating current is more suitable for electrodeposition of the metal impurities. Those skilled in the art can appropriately set the conditions for electrodepositing the metal impurities onto the electrode surfaces.

[0027] By miniaturizing or removing the metal impurities, it is possible to prevent the metal impurities themselves from causing a short circuit between the positive and negative electrodes. In addition, in an electricity storage device in which an electrolyte is interposed between the positive and negative electrodes, if the slurry for the positive electrode contains metal impurities, the metal impurities may dissolve into the electrolyte during charging of the electricity storage device, and may be reduced and precipitated on the surface of the negative electrode. If this precipitation is repeated, the metal impurities grow into dendrites, penetrate the separator, reach the positive electrode, and cause a short circuit. The larger the size of the metal impurities, the more likely they are to cause a short circuit due to dendrites. Therefore, by miniaturizing or removing the metal impurities, it is possible to prevent a short circuit due to dendrites. Therefore, by passing a current through the liquid to be treated by the impurity treatment device 100, it is possible to remove the metal impurities in the liquid to be treated, and even if they remain in the liquid to be treated, they can be converted into a form that is less likely to adversely affect the performance of the electricity storage device.

[0028] The application of voltage from the power supply unit 106 is controlled by the control device 107, for example. The control device 107 is realized as a hardware configuration by elements and circuits including a computer CPU and memory, and as a software configuration by a computer program or the like. Those skilled in the art will understand that these functional blocks can be realized in various forms by combining hardware and software. The control device 107 controls the power supply unit 106, for example, based on the value of the current flowing from the power supply unit 106 and the time for which the current flows. In this case, the control device 107 constitutes a part of the impurity treatment device 100. Note that the on / off of the power supply unit 106 may be controlled independently of the control device 107. The control device 107 may control the valve 4 and the pump 8.

[0029] As described above, the impurity treatment device 100 according to this embodiment includes a pipe 102 through which the liquid to be treated containing metal impurities flows, a first electrode 108 and a second electrode 110 disposed in the pipe 102, and a power supply unit 106 for passing a current between the first electrode 108 and the second electrode 110. The impurity treatment device 100 according to this embodiment micronizes or removes metal impurities by passing a current through the liquid to be treated, so that even if the impurities are non-magnetic metals, they can be treated. Therefore, the treatment rate of impurities can be increased. In addition, since a current is passed through the liquid to be treated flowing in the pipe 102, it is possible to treat the metal impurities while transporting the liquid to be treated. In addition, the micronized metal impurities can be carried along with the flow of the liquid to be treated and widely dispersed.

[0030] As an example, the liquid to be treated is at least one of an electrode slurry containing a solvent and an electrode active material and an electrode slurry containing a solvent and a conductive assistant. The piping 102 is provided in a coating device 1 including a coating die 2 for applying the liquid to a substrate 16 and a tank 6 for storing the liquid to be treated. This allows impurity treatment to be performed during the process of transporting the liquid to be treated from the tank 6 to the coating die 2. In addition, by disposing the impurity treatment device 100 in the feed piping 10 or the die supply piping 14 of the coating device 1, the liquid to be treated can be subjected to impurity treatment until just before it is applied to the substrate 16. Therefore, the impurity treatment device 100 of this embodiment can improve the performance of the electronic device.

[0031] Moreover, the impurity treatment device 100 can be installed in an existing device by simply using part of the piping in the device as the piping 102, or by simply replacing part of the piping with the piping 102 of the impurity treatment device 100. Therefore, the impurity treatment device 100 can be easily installed, replaced, and maintained.

[0032] In the impurity treatment device 100 of this embodiment, the first electrode 108 is provided on the pipe 102, and the second electrode 110 is provided on a rod-shaped body 112 inserted into the pipe 102. This allows the structures of the first electrode 108 and the second electrode 110 to be simplified. The rod-shaped body 112 is a hollow body, a solid body, or a cylindrical mesh. When the rod-shaped body 112 is a hollow body or a solid body, it is possible to suppress an increase in pressure loss when the liquid to be treated passes through the pipe 102. When the rod-shaped body 112 is a cylindrical mesh, it is possible to increase the contact area between the second electrode 110 and the liquid to be treated, thereby increasing the impurity treatment rate.

[0033] (Embodiment 2) The second embodiment has a common configuration with the first embodiment, except for the arrangement of the first electrode 108 and the second electrode 110. Below, the present embodiment will be described focusing on the configuration different from the first embodiment, and the common configuration will be described briefly or omitted.

[0034] Figures 3A to 3F are schematic diagrams of electrode unit 104 included in impurity treatment apparatus 100 according to embodiment 2. Figure 3A is a fourth example of electrode unit 104, Figure 3B is a fifth example of electrode unit 104, Figure 3C is a sixth example of electrode unit 104, Figure 3D is a seventh example of electrode unit 104, Figure 3E is an eighth example of electrode unit 104, and Figure 3F is a ninth example of electrode unit 104. Also, Figures 3A to 3F show a state in which the inner wall of pipe 102 is unfolded.

[0035] In the electrode section 104 of the present embodiment, the first electrode 108 and the second electrode 110 are provided in the pipe 102. The first electrode 108 and the second electrode 110 are provided at least on the inner wall of the pipe 102. The first electrode 108 and the second electrode 110 may be provided only on the surface of the inner wall of the pipe 102, or may be provided up to the inside of the inner wall. An insulating section 114 is provided between the first electrode 108 and the second electrode 110. The insulating section 114 electrically insulates the first electrode 108 and the second electrode 110.

[0036] In the fourth example shown in FIG. 3A, the first electrode 108 is laid in approximately 1 / 2 of the area in the circumferential direction on the inner wall of the pipe 102, and the second electrode 110 is laid in the remaining approximately 1 / 2 of the area. The first electrode 108 and the second electrode 110 extend in the direction in which the liquid to be treated flows. In the fifth example shown in FIG. 3B, a plurality of first electrodes 108 and a plurality of second electrodes 110 extending in the direction in which the liquid to be treated flows are alternately arranged in the circumferential direction of the inner wall of the pipe 102. The fourth and fifth examples have a structure in which the first electrodes 108 and the second electrodes 110 are arranged in a stripe pattern. In the fifth example, the area of ​​each electrode is smaller than that of the fourth example, and the layout pattern of each electrode is denser. Therefore, the fifth example can be suitably adopted for a pipe 102 having a larger inner diameter than the fourth example.

[0037] In a sixth example shown in Fig. 3C, the first electrode 108 and the second electrode 110 are each comb-shaped and are laid so as to interdigitate with each other. In a seventh example shown in Fig. 3D, the first electrode 108 and the second electrode 110 are laid in a spiral shape.

[0038] In the eighth example shown in FIG. 3E, the first electrode 108 is laid in approximately half of the area of ​​the inner wall of the pipe 102 in the direction in which the liquid to be treated flows, and the second electrode 110 is laid in approximately the remaining half of the area. The first electrode 108 and the second electrode 110 extend in the circumferential direction of the pipe 102. In the ninth example shown in FIG. 3F, a plurality of first electrodes 108 and a plurality of second electrodes 110 extending in the circumferential direction of the pipe 102 are alternately arranged in the direction in which the liquid to be treated flows. In the eighth and ninth examples, the first electrode 108 and the second electrode 110 are ring-shaped. In the ninth example, the area of ​​each electrode is smaller than that of the eighth example, and the layout pattern of each electrode is denser. Therefore, the ninth example can be suitably adopted for the electrode part 104 that is long in the direction in which the liquid to be treated flows, compared to the eighth example.

[0039] The above describes the embodiments of the present disclosure in detail. The above-mentioned embodiments merely show specific examples of implementing the present disclosure. The contents of the embodiments do not limit the technical scope of the present disclosure, and many design changes such as changes, additions, and deletions of components are possible within the scope of the idea of ​​the present disclosure defined in the claims. A new embodiment with design changes has the effects of the combined embodiments and modifications. In the above-mentioned embodiments, the contents for which such design changes are possible are emphasized by adding notations such as "in this embodiment" and "in this embodiment", but design changes are permitted even in contents without such notations. Any combination of the above components is also valid as an aspect of the present disclosure. The hatching on the cross section of the drawing does not limit the material of the object to which the hatching is added.

[0040] The invention according to the above-described embodiment may be specified by the items described below.

[0041] [Item 1] The liquid to be treated containing metal impurities is passed through a pipe (102); Passing an electric current through the liquid to be treated flowing through the pipe (102), Impurity treatment method. [Explanation of symbols]

[0042] 1 Coating device 2 Coating die 6. Tank 16 Object to be coated 100 Impurity treatment device 102 Piping 106 Power supply section 108 1st electrode 110 2nd electrode 112 Rod-shaped body

Claims

1. A cylindrical pipe through which a liquid to be treated containing metal impurities flows; a first electrode and a second electrode disposed in the pipe; a power supply unit that applies a current between the first electrode and the second electrode, The first electrode is disposed on an inner wall of the pipe, the second electrode is disposed on an outer wall of a rod-shaped body that is disposed so as to pass through a center of a cylinder of the piping; The distance between the first electrode and the second electrode is constant in the longitudinal direction and the circumferential direction of the pipe. Impurity treatment equipment.

2. The rod-shaped body is a hollow body, a solid body or a cylindrical mesh; The impurity treatment device according to claim 1 .

3. The liquid to be treated is at least one of an electrode slurry containing a solvent and an electrode active material and an electrode slurry containing a solvent and a conductive assistant. The impurity treatment device according to claim 1 or 2.

4. The piping is provided in a coating device including a coating die for applying the liquid to a substrate and a tank for storing the liquid to be treated. The impurity treatment device according to any one of claims 1 to 3.

5. The liquid to be treated containing metal impurities is passed through a cylindrical pipe, The method includes passing an electric current through the liquid to be treated flowing through the pipe; A first electrode and a second electrode are disposed within the pipe, The first electrode is disposed on an inner wall of the pipe, the second electrode is disposed on an outer wall of a rod-shaped body that is disposed so as to pass through a center of a cylinder of the piping; The distance between the first electrode and the second electrode is constant in the longitudinal direction and the circumferential direction of the pipe. Impurity treatment method.

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