Manufacturing method of electrode for secondary battery and manufacturing device of electrode for secondary battery

Abstract

To suppress deterioration of the quality of the electrode for the secondary battery by removing foreign matter from the active material particles.SOLUTION: A method for manufacturing an electrode for a secondary battery includes a mixing step S2 of mixing active material particles 4, a removal step S4 of removing foreign matter F from the mixed active material particles 4, and a forming step S5 of forming the active material particles 4 from which the foreign matter F has been removed into a sheet shape on a current collector 3. The removal step S4 includes a magnetizing step S4a of magnetizing the foreign matter F, and an attracting step S4b of attracting the magnetized foreign matter with a magnet 38.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing an electrode for a secondary battery and an apparatus for manufacturing an electrode for a secondary battery. [Background technology]

[0002] For example, as shown in Patent Document 1, electrodes constituting secondary batteries are generally produced by mixing active material particles, supplying the mixed active material particles to a current collector, and forming the active material particles supplied to the current collector into a sheet shape. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-92622 Summary of the Invention [Problem to be solved by the invention]

[0004] When the active material particles are mixed or transported, foreign matter may be mixed into the active material particles, which may lead to a deterioration in the quality of the electrode and ultimately to a deterioration in the quality of the secondary battery.

[0005] The present disclosure has been made in view of the above points, and its object is to prevent deterioration in the quality of an electrode for a secondary battery by removing foreign matter from active material particles. [Means for solving the problem]

[0006] The method for manufacturing an electrode for a secondary battery according to the present disclosure includes a mixing step of mixing active material particles, a removal step of removing foreign matter from the mixed active material particles, and a forming step of forming the active material particles from which the foreign matter has been removed into a sheet-like form on a current collector, and the removal step includes a magnetization step of magnetizing the foreign matter, and an adsorption step of adsorbing the magnetized foreign matter with a magnet.

[0007] The manufacturing apparatus for an electrode for a secondary battery according to the present disclosure includes a mixing section in which active material particles are mixed, a removal section in which foreign matter is removed from the mixed active material particles, and a formation section in which the active material particles from which the foreign matter has been removed are formed into a sheet on a current collector, and the removal section includes a magnetization section in which the foreign matter is magnetized, and an attraction section in which the magnetized foreign matter is attracted by a magnet. [Effects of the Invention]

[0008] According to the present disclosure, by removing foreign matter from active material particles, deterioration in the quality of electrodes for secondary batteries can be suppressed. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing a manufacturing apparatus for an electrode for a secondary battery according to the first embodiment. [Figure 2] FIG. 2 shows the active material particles and binder according to the first embodiment. [Figure 3] FIG. 3 shows the mixing section and the removal section in the manufacturing apparatus according to the first embodiment. [Figure 4] FIG. 4 is a flowchart showing a method for manufacturing an electrode for a secondary battery according to the first embodiment. [Figure 5] FIG. 5 is a schematic diagram showing a manufacturing apparatus for an electrode for a secondary battery according to the second embodiment. [Figure 6] FIG. 6 is a schematic diagram showing a manufacturing apparatus for an electrode for a secondary battery according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0011] First Embodiment (Secondary battery) The secondary battery includes a lithium-ion secondary battery, a lithium-sulfur secondary battery, etc. The electrode includes an active material layer formed on a current collector. The electrode includes a positive electrode and a negative electrode. The active material layer includes an active material and a binder. The active material layer may further include a conductive additive.

[0012] Known materials can be used for the current collector, active material, binder, and conductive additive. For example, in the case of a lithium-ion secondary battery, aluminum foil or the like is used for the positive electrode current collector, and copper foil or the like is used for the negative electrode current collector. For example, lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium iron phosphate (LiFePO4), or the like is used for the positive electrode active material. Graphite, silicon, lithium metal, or the like is used for the negative electrode active material. Polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or the like is used for the binder. Carbon materials such as carbon black and acetylene black are used for the conductive additive.

[0013] (Electrode manufacturing equipment for secondary batteries) 1 schematically shows an apparatus 1 for manufacturing an electrode 2 for a secondary battery. The apparatus 1 is used to manufacture an electrode 2 for a secondary battery. The apparatus 1 for manufacturing an electrode 2 for a secondary battery includes a current collector transport unit 10, a mixing unit 20, a removing unit 30, a supply unit 40 as part of a forming unit 90, a molding unit 50 as part of the forming unit 90, a heat pressing unit 60, an active material particle transport unit 70 as a transport unit, and a coating unit 80.

[0014] The current collector transport unit 10 is configured, for example, by a roll-to-roll mechanism. The current collector transport unit 10 transports the current collector 3. The current collector transport unit 10 includes a feed roll 11, a take-up roll 12, and two guide rolls 13. In the transport direction of the current collector 3 in the current collector transport unit 10, the feed roll 11 is disposed on the upstream side, the take-up roll 12 is disposed on the downstream side, and the guide roll 13 is disposed between the feed roll 11 and the take-up roll 12.

[0015] The current collector 3 is fed from a feed roll 11, transported from the upstream side to the downstream side along a predetermined transport path, and then taken up by a take-up roll 12. The current collector 3 is supported and guided by a guide roll 13 between the feed roll 11 and the take-up roll 12.

[0016] The mixing section 20, the removing section 30, the active material particle transporting section 70 and the covering section 80 will be described later.

[0017] The supply unit 40 is disposed downstream of the delivery roll 11 and upstream of the take-up roll 12 in the current collector transport unit 10. In the supply unit 40, active material particles 4 are supplied to the current collector 3. The supply unit 40 is configured, for example, as a hopper. The active material particles 4 are stored in the supply unit 40. When the hopper is opened, the active material particles 4 stored in the supply unit 40 are supplied to the current collector 3 transported by the current collector transport unit 10. In addition to the active material particles 4, the supply unit 40 also stores a binder. The supply unit 40 may further store a conductive additive.

[0018] The shaping unit 50 is disposed downstream of the supply unit 40 and upstream of the take-up roll 12 of the current collector transport unit 10. In the shaping unit 50, the active material particles 4 supplied to the current collector 3 are shaped into a sheet. The shaping unit 50 is configured, for example, by a pair of rolling rolls 51. The shaping unit 50 adjusts the gap between the rolling rolls 51 and the transported current collector 3. The shaping unit 50 adjusts the thickness of the active material particles 4 shaped into a sheet (hereinafter referred to as "active material particle sheet 5"). The shaping unit 50 rolls the active material particles 4. The shaping unit 50 may be configured by a squeegee.

[0019] In this manner, in the forming section 90 (supply section 40 and shaping section 50), the active material particles 4 are formed into a sheet shape on the current collector 3.

[0020] The heat pressing unit 60 is disposed downstream of the molding unit 50 and upstream of the winding roll 12 of the current collector transport unit 10. In the heat pressing unit 60, active material particles 4 formed in a sheet shape (active material particle sheet 5) are heat pressed to form an active material layer 6 on the current collector 3. In this way, an electrode 2 is manufactured in which the active material layer 6 is formed on the current collector 3.

[0021] The heat press unit 60 is composed of, for example, a planar heating unit 61 that heats the active material particle sheet 5 in a non-contact manner, and a heat roll press unit 62 that is arranged downstream of the planar heating unit 61. The planar heating unit 61 is composed of, for example, an infrared lamp. The heat roll press unit 62 is composed of, for example, a pair of heat rolls.

[0022] In the hot pressing section 60, the binder 7 (described below) coated on the surfaces 4a of the active material particles 4 melts, and the active material particles 4 are compressed, thereby binding the active material particles 4 to each other and to the current collector 3 via the binder 7. This results in an active material layer 6 having low contact resistance between the active material particles 4 and strong adhesive strength between the active material particles 4 and the current collector 3.

[0023] The electrode 2 formed in the hot press section 60 is taken up by the take-up roll 12 of the current collector transport section 10 arranged downstream of the hot press section 60 .

[0024] (Active material particles and binder) FIG. 2 shows the active material particles 4 and the binder 7. The coating unit 80 is disposed on the most upstream side of the flow of the active material particles 4 in the manufacturing apparatus 1 (see FIG. 1). In detail, in the coating unit 80, the binder 7 and the conductive additive 8 are dispersed and coated on the surfaces 4a of the active material particles 4. In the coating unit 80, the active material particles 4 are dispersed in a solvent in which the binder 7 and the conductive additive 8 are dissolved, and then the solvent is evaporated, whereby the binder 7 and the conductive additive 8 are dispersed and coated on the surfaces 4a of the active material particles 4.

[0025] Alternatively, in the coating section 80, the active material particles 4 may be mixed and heated with the binder 7 and conductive additive 8 having a particle size smaller than that of the active material particles 4. When the surfaces 4a of the active material particles 4 are not coated with the conductive additive 8, a mixture of the active material particles 4 (whose surfaces 4a are coated with the binder 7) and the conductive additive 8 may be supplied to the current collector 3. The conductive additive 8 may not be required.

[0026] (Mixing section and removal section) 3 shows the mixing section 20 and the removal section 30 in the manufacturing apparatus 1. The mixing section 20 and the removal section 30 are located downstream of the coating section 80 and upstream of the supply section 40 in the flow of the active material particles 4.

[0027] The mixing section 20 is located downstream of the coating section 80 and upstream of the removal section 30 in the flow of the active material particles 4. The active material particles 4 are mixed in the mixing section 20. The mixing section 20 includes a mixing container 21. The mixing container 21 is made of a non-magnetic material, such as stainless steel. The wall of the mixing container 21 is provided with an inlet 21a and an outlet 21b.

[0028] In the mixing unit 20, the active material particles 4 flow into the mixing container 21 through the inlet 21a. Specifically, the active material particles 4, whose surfaces 4a have been coated with the binder 7 in the coating unit 80, flow into the mixing container 21 through the inlet 21a. In the mixing container 21 of the mixing unit 20, the active material particles 4, whose surfaces 4a have been coated with the binder 7 in the coating unit 80, are mixed. In the mixing container 21 of the mixing unit 20, the active material particles 4 are mixed together with the binder 7 (which has been coated on the surfaces 4a of the active material particles 4).

[0029] When the binder 7 is not coated on the surfaces 4a of the active material particles 4, the active material particles 4 and the binder 7 may be separately introduced into the mixing container 21 through the inlet 21a. The conductive additive 8 may be coated on the surfaces 4a of the active material particles 4 together with the binder 7 in the coating section 80. Alternatively, the conductive additive 8 may be introduced into the mixing container 21 through the inlet 21a separately from the active material particles 4 and the binder 7.

[0030] In the coating section 80, before the active material particles 4 are mixed in the mixing section 20, the surfaces 4a of the active material particles 4 are coated with the binder 7.

[0031] In the mixing section 20, the active material particles 4 are discharged from the mixing container 21 through the outlet 21b.

[0032] The removal section 30 is located downstream of the mixing section 20 and upstream of the supply section 40 in the flow of the active material particles 4. The removal section 30 will be described later.

[0033] The active material particle transport section 70 is located downstream of the mixing section 20 and upstream of the removal section 30 in the flow of the active material particles 4. The active material particle transport section 70 includes a transport pipe 71 as a pipe. The upstream end of the transport pipe 71 is connected to the outlet 21b of the mixing container 21.

[0034] In the active material particle transport section 70, the active material particles 4 mixed in the mixer 20 are transported by a transport pipe 71. The transport pipe 71 is formed, for example, in a cylindrical shape. The transport pipe 71 is made of a non-magnetic material. For example, the transport pipe 71 is made of stainless steel.

[0035] When the active material particles 4 are mixed and transported, there is a possibility that foreign matter F may become mixed with the active material particles 4. If foreign matter F becomes mixed with the active material particles 4, this may lead to a deterioration in the quality of the electrode 2 and ultimately to a deterioration in the quality of the secondary battery. The foreign matter F may be, for example, non-magnetic metal pieces peeled off from the mixing container 21 of the mixing unit 20 or the transport piping 71 of the active material particle transport unit 70. In this embodiment, the foreign matter F is removed from the active material particles 4 by applying the method described below. This prevents a deterioration in the quality of the electrode 2 for a secondary battery.

[0036] The removal unit 30 is located downstream of the active material particle transport unit 70 and upstream of the supply unit 40 in the flow of the active material particles 4. The removal unit 30 includes a magnetized unit 31 and an adsorption unit 36. In the flow of the active material particles 4 in the removal unit 30, the magnetized unit 31 is located upstream and the adsorption unit 36 ​​is located downstream.

[0037] The magnetization unit 31 includes a magnetization container 32 and a coil 33. The magnetization container 32 is formed, for example, in a cylindrical shape. The upstream end of the magnetization container 32 is connected to the downstream end of the conveying pipe 71. The coil 33 is provided on the inner peripheral wall of the magnetization container 32. The active material particles 4 pass along the inner peripheral side of the coil 33.

[0038] An electric current is passed through the coil 33 of the magnetized portion 31. In the magnetized portion 31, the non-magnetic foreign matter F (hereinafter referred to as "non-magnetic foreign matter Fa") is magnetized by the coil 33. As a result, the non-magnetic foreign matter Fa is transformed into a magnetic foreign matter F (hereinafter referred to as "magnetic foreign matter Fb").

[0039] The adsorption section 36 includes an adsorption vessel 37 and a magnet 38. The adsorption vessel 37 is formed, for example, in a cylindrical shape. The upstream end of the adsorption vessel 37 is connected to the downstream end of the magnetization vessel 32. The magnet 38 is provided, for example, on the upper inner circumferential wall of the adsorption vessel 37. The active material particles 4 pass below the magnet 38.

[0040] In the attracting section 36, the foreign matter F (magnetic foreign matter Fb) magnetized by the magnetizing section 31 is attracted by the magnet 38.

[0041] In this way, the foreign matter F is removed from the active material particles 4 mixed in the mixer 20 in the remover 30 (the magnetized section 31 and the adsorbing section 36).

[0042] The active material particles 4 from which the foreign matter F has been removed in the removal unit 30 are sent to the supply unit 40. In the supply unit 40, the active material particles 4 from which the foreign matter F has been removed are supplied to the current collector 3. In the forming unit 50, the active material particles 4 supplied to the current collector 3 are formed into a sheet shape to become an active material particle sheet 5. In summary, in the forming unit 90 (supply unit 40 and forming unit 50), the active material particles 4 from which the foreign matter F has been removed are formed into a sheet shape on the current collector 3.

[0043] In the hot pressing section 60, the active material particles 4 formed in a sheet shape (active material particle sheet 5) are hot pressed to form an active material layer 6 on the current collector 3. In this way, an electrode 2 is produced in which the active material layer 6 is formed on the current collector 3.

[0044] (Method of manufacturing electrodes for secondary batteries) 4 is a flowchart showing a method for manufacturing the electrode 2 for a secondary battery. The method for manufacturing the electrode 2 for a secondary battery includes a coating step S1, a mixing step S2, a transporting step S3, a removing step S4, a supplying step S5a as part of the forming step S5, a molding step S5b as part of the forming step S5, and a heat pressing step S6.

[0045] As shown in FIG. 2, in the coating step S1, prior to the mixing step S2, the surfaces 4a of the active material particles 4 are coated with the binder 7. Specifically, in the coating step S1, the active material particles 4 are dispersed in a solvent in which the binder 7 has been dissolved, and the solvent is then evaporated to coat the surfaces 4a of the active material particles 4 with the binder 7. Alternatively, in the coating step S1, the active material particles 4 and the binder 7 having a particle size smaller than that of the active material particles 4 are mixed and heated. Note that in the coating step S1, the surfaces 4a of the active material particles 4 may be coated with the conductive additive 8 together with the binder 7.

[0046] 3, in the mixing step S2, the active material particles 4 (whose surfaces 4a are coated with the binder 7) are mixed in a mixing container 21. In the mixing step S2, the active material particles 4 are mixed together with the binder 7 (whose surfaces 4a are coated with the active material particles 4). The mixing container 21 is made of a non-magnetic material.

[0047] The transport step S3 is located between the mixing step S2 and the removing step S4. In the transport step S3, the active material particles 4 mixed in the mixing step S2 are transported by a transport pipe 71. The transport pipe 71 is made of a non-magnetic material.

[0048] When the active material particles 4 are mixed and transported, there is a possibility that foreign matter F may become mixed with the active material particles 4. The foreign matter F is, for example, non-magnetic metal pieces peeled off from the mixing container 21 of the mixing unit 20 or the transport piping 71 of the active material particle transport unit 70.

[0049] The removal step S4 includes a magnetization step S4a and an attraction step S4b. In the magnetization step S4a, non-magnetic foreign matter F (non-magnetic foreign matter Fa) is magnetized by the coil 33. This causes the non-magnetic foreign matter Fa to transform into magnetic foreign matter F (magnetic foreign matter Fb). In the attraction step S4b, the foreign matter F (magnetic foreign matter Fb) magnetized in the magnetization step S4a is attracted by the magnet 38.

[0050] In this manner, in the removing step S4 (the magnetizing step S4a and the adsorbing step S4b), the foreign matter F is removed from the active material particles 4 mixed in the mixing step S2.

[0051] In the supplying step S5a, the active material particles 4 from which the foreign matter F has been removed are supplied to the current collector 3. In the forming step S5b, the active material particles 4 supplied to the current collector 3 are formed into a sheet to form an active material particle sheet 5. In summary, in the forming step S5 (supplying step S5a and forming step S5b), the active material particles 4 from which the foreign matter F has been removed in the removing step S4 are formed into a sheet on the current collector 3.

[0052] In addition, if the surfaces 4a of the active material particles 4 are not coated with the conductive additive 8 in the coating step S1, a mixture of the active material particles 4 (whose surfaces 4a are coated with the binder 7) and the conductive additive 8 may be supplied to the current collector 3 in the supply step S5a.

[0053] In the hot pressing step S6, the active material particles 4 formed into a sheet shape (active material particle sheet 5) are hot pressed to form an active material layer 6 on the current collector 3. In this way, an electrode 2 is produced in which the active material layer 6 is formed on the current collector 3.

[0054] (Action and effect) In the removal unit 30 (removal step S4), the magnetization unit 31 (magnetization step S4a) magnetizes the non-magnetic foreign matter Fa with the coil 33 to transform it into magnetic foreign matter Fb, and the attraction unit 36 ​​(attraction step S4b) attracts the magnetic foreign matter Fb with the magnet 38.

[0055] As a result, even if non-magnetic foreign matter F is mixed into the active material particles 4, the foreign matter F can be removed from the active material particles 4 in the removal unit 30 (removal step S4).

[0056] By removing the foreign matter F from the active material particles 4, deterioration in the quality of the electrode 2 for a secondary battery can be suppressed.

[0057] Since the active material particles 4 are mixed together with the binder 7, the active material particles 4 can be easily bound together by the binder 7.

[0058] By coating the surfaces 4a of the active material particles 4 with the binder , the active material particles 4 and the binder can be easily mixed together.

[0059] After dispersing the active material particles 4 in a solvent in which the binder 7 has been dissolved, the solvent is evaporated, whereby the surfaces 4a of the active material particles 4 can be easily coated with the binder 7.

[0060] Active material particles 4 formed in a sheet shape (active material particle sheet 5) are hot-pressed to form an active material layer 6 on the current collector 3. By employing a so-called dry process, an electrode 2 having an active material layer 6 formed on the current collector 3 can be easily manufactured.

[0061] Second Embodiment A second embodiment will be described. In the following description, the same components as those in the above embodiment will be denoted by the same reference numerals, and detailed description will be omitted. Figure 5 schematically shows a manufacturing apparatus 1 for a secondary battery electrode 2 according to the second embodiment.

[0062] The manufacturing apparatus 1 includes a slurry forming section 100. In the slurry forming section 100, the active material particles 4 from which the foreign matter F has been removed in the removing section 30 are formed into a slurry 9 together with a binder 7. The manufacturing method includes a slurry forming step S7. The slurry forming step S7 is located between the removing step S4 and the forming step S5 (the supplying step S5a and the shaping step S5b). In the slurry forming step S7, the active material particles 4 are formed into a slurry 9 together with the binder 7.

[0063] The manufacturing apparatus 1 does not need to include the coating unit 80 and / or the hot-press unit 60. The manufacturing method does not need to include the coating step S1 and / or the hot-press step S6. The active material particles 4 may be formed as a slurry 9 together with not only the binder 7 but also the conductive additive 8.

[0064] The other configurations are the same as those in the first embodiment.

[0065] According to this embodiment, by employing a so-called wet process, it is possible to manufacture the electrode 2 in which the active material layer 6 is formed on the current collector 3. It is possible to prevent the foreign matter F from being mixed into the slurry 9.

[0066] Third Embodiment A third embodiment will be described. In the following description, the same components as those in the above embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted. Figure 6 schematically shows an apparatus for manufacturing an electrode 2 for a secondary battery according to the third embodiment.

[0067] In the above embodiment, the forming section 90 (forming step S5) was composed of a supply section 40 (supply step S5a) and a molding section 50 (molding step S5b) separately, but this is not limited to this, and for example, the two may be integrated.

[0068] Specifically, the forming unit 90 includes a hopper 91, a pair of rollers 92, and a forming roller 93. In the forming unit 90, the active material particles 4 are dropped from the hopper 91 in which the active material particles 4 are stored into the gap between the pair of rollers 92, and the sheet-like active material particles 4 are supplied through the gap between the pair of rollers 92 to the current collector 3 and formed by the forming roller 93.

[0069] In the forming section 90, the active material particles 4 are formed into a sheet shape on the current collector 3. In the forming step S5, the active material particles 4 are formed into a sheet shape on the current collector 3.

[0070] <Other embodiments> Although the present disclosure has been described above with reference to preferred embodiments, such description is not limiting, and it goes without saying that various modifications, substitutions, or combinations are possible.

[0071] The mixing vessel 21 and / or the conveying pipe 71 may be made of a magnetic material.

[0072] The mixing step S2 and the removing step S4 may be carried out simultaneously.

[0073] The conductive additive 8 may be omitted. [Industrial Applicability]

[0074] The present disclosure is applicable to a method for manufacturing an electrode for a secondary battery and an apparatus for manufacturing an electrode for a secondary battery, and is therefore extremely useful and has high industrial applicability. [Explanation of symbols]

[0075] F Foreign object Fa non-magnetic foreign matter Fb magnetic foreign matter 1 Manufacturing equipment 2 electrodes 3 Current collector 4 Active material particles 4a surface 5. Active material particle sheet 6 Active material layer 7. Binder 8 Conductive additives 9. Slurry 10 Current collector transport section 11 Sending Roll 12 Winding roll 13 Guide Roll 20 Mixing section 21 Mixing container 21a Inlet 21b Outlet 30 Removal part 31 Magnetized part 32 Magnetized container 33 Coil 36 Adsorption part 37 Adsorption container 38 Magnet 40 Supply section 50 Molding section 51 Rolling mill 60 Heat Press Section 61 Planar heating section 62 Heating roll press section 70 Active material particle transport section (transport section) 71 Conveying piping (piping) 80 Covering part 90 Formation part 91 Hopper 92 Pair of Rollers 93 Forming roller 100 Slurry forming section S1 Coating process S2 mixing process S3 Transportation process S4 removal process S4a Magnetization process S4b Adsorption process S5 forming process S5a Supply process S5b Molding process S6 Heat press process S7 Slurry formation process

Claims

1. a mixing step of mixing active material particles; a removing step of removing foreign matter from the mixed active material particles; a forming step of forming the active material particles from which the foreign matter has been removed into a sheet shape on a current collector, The removing step includes: a magnetizing step of magnetizing the foreign matter; and an attraction step of attracting the magnetized foreign object with a magnet.

2. The method for manufacturing an electrode for a secondary battery according to claim 1 , wherein in the mixing step, the active material particles are mixed with a binder.

3. The method for producing an electrode for a secondary battery according to claim 2 , further comprising a coating step of coating the surfaces of the active material particles with a binder prior to the mixing step.

4. 4. The method for manufacturing an electrode for a secondary battery according to claim 3, wherein in the coating step, the active material particles are dispersed in a solvent in which the binder is dissolved, and then the solvent is evaporated to coat the surfaces of the active material particles with the binder.

5. 5. The method for producing an electrode for a secondary battery according to claim 2, further comprising a hot pressing step of hot pressing the active material particles formed into a sheet shape to form an active material layer on the current collector.

6. 2. The method for manufacturing an electrode for a secondary battery according to claim 1, further comprising a slurry forming step of forming a slurry of the active material particles together with a binder between the removing step and the forming step.

7. a conveying step of conveying the active material particles by a pipe between the mixing step and the removing step, 5. The method for manufacturing an electrode for a secondary battery according to claim 1, wherein the piping is made of a non-magnetic material.

8. a mixing section in which active material particles are mixed; a removal section in which foreign matter is removed from the mixed active material particles; a forming section in which the active material particles from which the foreign matter has been removed are formed into a sheet shape on a current collector, The removal unit a magnetized portion where the foreign matter is magnetized; an attraction section to which the magnetized foreign matter is attracted by a magnet.

9. The manufacturing apparatus for an electrode for a secondary battery according to claim 8 , wherein the active material particles are mixed with a binder in the mixing section.

10. 10. The manufacturing apparatus for an electrode for a secondary battery according to claim 9, further comprising a coating section in which surfaces of the active material particles are coated with a binder before the active material particles are mixed in the mixing section.

11. 11. The apparatus for manufacturing an electrode for a secondary battery according to claim 10, wherein in the coating section, the active material particles are dispersed in a solvent in which the binder is dissolved, and then the solvent is evaporated, thereby coating the surfaces of the active material particles with the binder.

12. 12. The manufacturing apparatus for an electrode for a secondary battery according to claim 9, further comprising a heat-pressing section that heat-presses the active material particles formed into a sheet shape to form an active material layer on the current collector.

13. 9. The manufacturing apparatus for an electrode for a secondary battery according to claim 8, further comprising a slurry forming section in which the active material particles from which the foreign matter has been removed in the removing section are formed into a slurry together with a binder.

14. a conveying section in which the active material particles mixed in the mixing section are conveyed by a pipe, 12. The manufacturing apparatus for an electrode for a secondary battery according to claim 8, wherein the piping is made of a non-magnetic material.

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