Method for manufacturing electrode structure and manufacturing apparatus

Abstract

Embodiments of the present application relate to a manufacturing method of an electrode structure and a manufacturing apparatus. A manufacturing method of an electrode structure is provided, which can appropriately suppress folding of an uncoated region even if the width dimension of the uncoated region is increased, after rolling of an active material-containing layer and bending correction of a belt-shaped body are performed. In the manufacturing method of the electrode structure, in a belt-shaped body in which an uncoated region in which the active material-containing layer is not formed is formed in one of a pair of long sides of a current collector and in the vicinity thereof, the active material-containing layer is rolled and a tension in a length direction is applied to the belt-shaped body between a rolling portion in which the active material-containing layer is rolled and a pulling portion in which the belt-shaped body is pulled. In the manufacturing method, between the rolling portion and the pulling portion, with respect to the belt-shaped body to which the tension is applied, a pair of holding members are brought into contact with the uncoated region of the current collector from opposite sides in a thickness direction of the belt-shaped body with respect to each other, and thereby the uncoated region is held between the pair of holding members.

Description

Technical Field

[0001] The embodiments of the present invention relate to a method and apparatus for manufacturing an electrode structure. Background Technology

[0002] In batteries such as secondary batteries, electrodes such as positive and negative electrodes are formed by electrode structures. Each electrode structure includes a current collector and an active material layer coated on the surface of the current collector. The current collector has a pair of long sides along its length. In the current collector of the electrode structure, an uncoated area is formed on one of the long sides and its vicinity, where neither of the two main surfaces is coated with the active material layer. In the manufacture of such an electrode structure, with the uncoated area on one of the long sides and its vicinity formed in the current collector, an active material layer is coated on the surface of the current collector. Furthermore, after the active material layer coated on the current collector is dried, the active material layer is rolled using a rolling mill or similar device while the strip containing the active material layer on the current collector is being transported.

[0003] In the manufacture of the electrode structure, by rolling an active material layer as described above, in the coated area where the active material layer is applied to at least one of a pair of main surfaces of the current collector, the current collector is elongated along its length due to the pressure generated by rolling. On the other hand, in the uncoated area of ​​the current collector, no rolling pressure is applied, so the current collector does not elongate along its length. Therefore, due to the rolling of the active material layer, the conveyed strip (current collector) is bent in a state where the side containing the uncoated area is bent on the inside.

[0004] In the manufacture of the electrode structure, the bending of the strip caused by rolling the active material layer is corrected. In correcting the bending of the strip, the strip is pulled downstream of the rolling section containing the active material layer, thereby applying tension in the length direction to the strip between the pulling section and the rolling section. Furthermore, for example, a protrusion is provided on the outer peripheral surface of the guide rollers that guide the strip between the rolling section and the pulling section, and the protrusion presses against the uncoated area of ​​the current collector in the tensioned strip, thereby stretching the uncoated area along the length direction and correcting the bending.

[0005] In batteries using electrodes formed from electrode structures, it is necessary to form a relatively large width dimension of the uncoated area in the strip. During the manufacturing of electrode structures with a large uncoated area width dimension, uneven elongation in the uncoated area occurs during the correction of the strip's bending caused by rolling the active material layer. For example, during the correction of the strip's bending, the elongation in the uncoated area is smaller in the region farther from the active material layer compared to the region closer to it. Because the elongation in the uncoated area becomes uneven during bending correction, the uncoated area becomes prone to folding. Therefore, in the manufacturing of electrode structures with a large uncoated area width dimension, it is necessary to appropriately suppress folding of the uncoated area after rolling the active material layer and correcting the strip's bending. Summary of the Invention

[0006] The problem to be solved by the present invention is to provide a method and apparatus for manufacturing an electrode structure, wherein even if the width of the uncoated area increases, the folding of the uncoated area is appropriately suppressed after rolling with an active material layer and correction of the bending of the strip.

[0007] According to the method for manufacturing an electrode structure according to the embodiment, a strip is conveyed, in which an active material layer is coated on the surface of a current collector, and an uncoated area without the active material layer is formed on one of a pair of long sides along the length direction and its vicinity. In the manufacturing method, the active material layer is rolled in the conveyed strip. Downstream of the rolling section where the active material layer is rolled, the strip is pulled downstream, thereby applying tension in the length direction to the strip between the pulling section and the rolling section. In the manufacturing method, between the rolling section and the pulling section, for the tensioned strip, a pair of holding members contact the uncoated area of ​​the current collector from opposite sides relative to each other in the thickness direction of the strip, thereby holding the uncoated area between the pair of holding members.

[0008] Based on the above configuration, a method and apparatus for manufacturing an electrode structure can be provided that appropriately suppresses folding of the uncoated area even when the width of the uncoated area increases, after rolling with an active material layer and correction of the bending of the strip. Attached Figure Description

[0009] Figure 1 This is a schematic diagram showing an example of an electrode structure formed in the embodiment, viewed from one side in the thickness direction.

[0010] Figure 2It is roughly represented by a cross section or approximately orthogonal to the length direction. Figure 1 A cross-sectional view of the electrode structure.

[0011] Figure 3 This is a schematic diagram illustrating an example of a manufacturing apparatus for producing an electrode structure in an embodiment.

[0012] Figure 4 This is a cross-sectional view of an example of the structure of the elongated section in the manufacturing apparatus of the embodiment, showing a section orthogonal or substantially orthogonal to the conveying direction in the conveying section.

[0013] Figure 5 This is a cross-sectional view of an example of the structure of the holding section in the manufacturing apparatus of the embodiment, showing a section orthogonal or substantially orthogonal to the conveying direction in the conveying section.

[0014] Figure 6 This is expressed as a view taken from the intersection of the conveying direction and the width direction of the conveying section. Figure 5 A schematic diagram of the retaining part.

[0015] Figure 7 It is roughly represented by a cross section that is orthogonal or approximately orthogonal to the width direction of the conveying section. Figure 5 Cross-sectional view of the retaining part.

[0016] Figure 8 In a certain modified manufacturing apparatus, a cross-sectional view is taken as a rough representation of the structure of the holding section, with a section orthogonal or approximately orthogonal to the conveying direction in the conveying section.

[0017] (Explanation of reference numerals in the attached diagram)

[0018] 1…Electrode structure, 1A…Strip, 2…Current collector, 3…Layer containing active material, 5, 6…Main surface, 7…Long side (first long side), 8…Long side (second long side), 10…Coating end, 11…Coated area, 12…Uncoated area, 15…Manufacturing apparatus, 16…Conveying section, 21…Rolling section, 22…Pulling section, 23…Elongating section, 24…Holding section, 25…Winding section, 41…Holding member (first holding member), 42…Holding member (second holding member), b…Width dimension, X…Dimension. Detailed Implementation

[0019] Hereinafter, the embodiments will be described with reference to the accompanying drawings.

[0020] In this embodiment, a method and apparatus for manufacturing an electrode structure are provided. The electrode structure manufactured in this embodiment is used in batteries such as secondary batteries to form a positive or negative electrode. Figure 1 as well as Figure 2This illustrates an example of an electrode structure 1 formed in an embodiment, etc. For example... Figure 1 as well as Figure 2 As shown, in electrode structure 1, the length direction (direction indicated by arrow L1), the width direction (direction indicated by arrow W1) which intersects (orthogonally or approximately orthogonally) the length direction, and the thickness direction (direction indicated by arrow T1) which intersects (orthogonally or approximately orthogonally) the length direction and the width direction. Figure 1 The view is shown from one side in the thickness direction. Figure 2 The cross-section is shown as orthogonal or approximately orthogonal to the length direction. In electrode structure 1, the dimensions in the length direction are larger than the dimensions in the width direction and the dimensions in the thickness direction, respectively, and the dimensions in the width direction are larger than the dimensions in the thickness direction.

[0021] In one example, the electrode structure 1 serves as the positive or negative electrode of a battery such as a lithium-ion secondary battery. In another example, the electrode structure 1 is divided into multiple electrode sheets along its length. Furthermore, each of the multiple electrode sheets serves as either the positive or negative electrode of the battery. The electrode structure 1 includes a current collector 2 and an active material layer 3 coated on the surface of the current collector 2. The current collector 2 is formed of a conductive metal and has a pair of main surfaces 5 and 6, and a pair of long sides 7 and 8. The main surfaces 5 and 6, and the long sides 7 and 8, extend along the length direction from one end of the electrode structure 1 to the other. Additionally, the main surfaces 5 and 6 extend from the long side 7 to the long side 8 along the width direction of the electrode structure 1. The main surface 5 faces one side in the thickness direction of the electrode structure 1, and the main surface 6 faces the opposite side in the thickness direction of the electrode structure 1.

[0022] The long side (first long side) 7 forms one edge of the current collector 2 in the width direction of the electrode structure 1. The long side (second long side) 8 forms the edge of the current collector 2 opposite to the long side 7 in the width direction of the electrode structure 1. Furthermore, the active material layer 3 extends from one end of the electrode structure 1 to the other in the length direction. Moreover, the active material layer 3 extends from the long side 8 of the current collector 2 to the coating end 10 in the width direction of the electrode structure 1. Viewed in the thickness direction, the end of the electrode structure 1 opposite to the coating end 10 in the width direction overlaps with the long side 8 of the current collector 2. The coating end 10 is located on the side where the long side 7 is located relative to the center position of the electrode structure 1 in the width direction. Therefore, the dimension between the long side 8 and the coating end 10 in the width direction of the electrode structure 1 is larger than the dimension between the long side 7 and the coating end 10 in the width direction of the electrode structure 1.

[0023] exist Figure 1 as well as Figure 2In one example, a coating region 11, containing the active material layer 3, is formed on both the long side 8 and the coating end 10 of the current collector 2, on both of its main surfaces 5 and 6. Furthermore, an uncoated region 12, where neither of the main surfaces 5 and 6 of the current collector 2 is coated or supports the active material layer 3, is formed on the long side 7 and the coating end 10 of the electrode structure 1. Therefore, in the current collector 2, an uncoated region 12, where neither of the main surfaces 5 and 6 is coated with the active material layer 3, is formed on or near the long side 7. In the electrode structure 1, the uncoated region 12 protrudes from the coating end 10 containing the active material layer 3 towards the side opposite to the side containing the long side 8 in the width direction. Alternatively, in another example, the active material layer 3 may be supported only on one of the main surfaces 5 and 6 of the current collector 2 within the coating region 11. Therefore, in the coating area 11, it is sufficient to coat and support the active material layer 3 on at least one of the pair of main surfaces 5 and 6 of the current collector 2.

[0024] When electrode structure 1 is used to form the positive electrode, the current collector 2 is not limited to this, and can be formed of any one of aluminum, aluminum alloy, stainless steel, and titanium, with a thickness of about 10 μm to 30 μm. The active material layer 3 may also contain a positive electrode active material, and may contain a binder and a conductive agent. The positive electrode active material is not limited to this, and examples include oxides, sulfides, and polymers that can intercalate and deintercalate lithium ions. The positive electrode active material may contain at least one selected from the group consisting of lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt aluminum composite oxide, lithium nickel cobalt manganese composite oxide, spinel lithium manganese nickel composite oxide, lithium manganese cobalt composite oxide, lithium iron oxide, lithium fluoride ferric sulfate, lithium iron composite phosphate compound, and lithium manganese composite phosphate compound.

[0025] As a conductive agent, one or more carbonaceous materials may be used. Examples of carbonaceous materials that serve as conductive agents include acetylene black, Ketjen black, graphite, and coke. Additionally, a polymer resin may be used as a binder. The binder may include at least one selected from the group consisting of free polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluoropolymers, styrene-butadiene rubber, ethylene-butadiene rubber, polypropylene (PP), polyethylene (PE), carboxymethyl cellulose (CMC), polyimide (PI), and polyacrylamide (PAI). Furthermore, an inorganic solid electrolyte may be included in the positive electrode containing the active material layer.

[0026] Inorganic solid particles are incorporated to improve the lithium-ion conductivity of the active material layer. The inorganic solid particles preferably contain at least one compound selected from the group consisting of metal oxides, lanthanide oxides, and sulfides. The metal oxide contains at least one element selected from the group consisting of Ti, Ge, Sr, Zr, Sn, Al, Sc, Y, Ba, P, and Ca. The sulfide contains at least one element selected from the group consisting of Li, Ge, P, Si, Sn, Al, Ga, B, and In. The lanthanide oxide is an oxide containing lanthanide elements such as La, Ce, Pr, and Nd. Additionally, the aforementioned metal oxide may also contain lanthanide elements such as La.

[0027] Examples of inorganic solid particles include oxide-based solid electrolytes and sulfide-based solid electrolytes. Among oxide-based solid electrolytes, lithium phosphate solid electrolytes with the general formula LiM2(PO4)3, having a NASICON (Sodium(Na) Super Ionic Conductor) type structure, are preferred. In the above general formula, M is, for example, at least one element selected from the group consisting of titanium (Ti), germanium (Ge), strontium (Sr), zirconium (Zr), tin (Sn), aluminum (Al), and calcium (Ca). The ionic conductivity of lithium phosphate solid electrolytes represented by the general formula LiM2(PO4)3 is, for example, 1 × 10⁻⁶. －5 S / cm or higher and 1×10 －3 Below S / cm.

[0028] As a specific example of a lithium phosphate solid electrolyte with a NASICON-type structure, LATP(Li 1+x+ y Al x (At least one of Ti and Ge) 2－x Si y P 3－y O 12 ;0<x≤2, 0≤y<3), Li 1+x Al x Ge 2－x (PO4)3; 0 ≤ x ≤ 2, and Li 1+x Al x Zr 2－x (PO4)3; 0 ≤ x ≤ 2, Li 1+2x Zr 1－x Ca x (PO4)3; 0 ≤ x < 1. Because Li 1+2x Zr 1－x Ca x (PO4)3 has high water resistance, low reducing power, and low cost, so it is preferred as an inorganic solid electrolyte particle.

[0029] In addition to the aforementioned lithium phosphate solid electrolyte, amorphous LIPON (Li₂) can also be listed as an oxide-based solid electrolyte. 2.9 PO 3.3 N 0.46 ), garnet-type La 5+x A x La 3-x M2O 12 (A is selected from at least one of Ca, Sr and Ba, and M is at least one of Nb and Ta), Li3M 2-x L2O 12 (M is at least one of Ta and Nb, L is Zr), Li 7-3x Al x La3Zr3O 12 and LLZ(Li7La3Zr2O) 12 Solid electrolytes can be one type or a mixture of two or more. For example, LIPON has an ionic conductivity of 1 × 10⁻⁶. －6 S / cm or higher and 5×10 －6 Below S / cm. The ionic conductivity of LLZ is, for example, 1×10⁻⁶. －4 S / cm or higher and 5×10 －4 Below S / cm.

[0030] When electrode structure 1 is used to form the negative electrode, the current collector 2 is not limited to this, and can be formed from any of zinc, aluminum, aluminum alloy, and copper, with a thickness of approximately 10 μm to 30 μm. The negative electrode active material layer may also contain a negative electrode active material, and may contain a binder and a conductive agent. The negative electrode active material is not particularly limited, and examples include metal oxides, metal sulfides, metal nitrides, and carbonaceous materials capable of intercalating and deintercalating lithium ions. As a metal oxide that serves as the negative electrode active material, titanium oxides can be listed. Moreover, titanium oxides that serve as negative electrode active materials may include, for example, titanium oxide, lithium titanium oxide, niobium titanium oxide, and sodium niobium titanium oxide. As conductive agents and binders, the same materials as those used in the formation of the positive electrode can be listed. In addition, as in the formation of the positive electrode, an inorganic solid electrolyte may also be contained in the negative electrode active material layer. As an inorganic solid electrolyte, the same materials as those used in the formation of the positive electrode can be listed.

[0031] In the manufacture of electrode structure 1, a slurry is prepared by suspending an active material (which will become the positive or negative electrode active material), a conductive agent, and a binder in an organic solvent or pure water. At this time, regarding the proportions of the active material, conductive agent, and binder, the active material is preferably 70% or more and 95% or less by mass, the conductive agent is preferably 2% or more and 20% or less by mass, and the binder is preferably 2% or more and 10% or less by mass. Furthermore, the prepared slurry is applied to the surface of current collector 2, and a strip containing an active material layer 3 is coated on the surface of current collector 2. The slurry application is performed, for example, using a coating head.

[0032] In the manufacture of electrode structure 1, electrode structure 1 is formed by performing the processes described later on a strip as described above. In the strip, the length direction, width direction, and thickness direction are defined in the same way as in electrode structure 1, and coated areas 11 and uncoated areas 12 are formed. Therefore, in the strip, in the current collector 2, an uncoated area 12 is formed on and near the long side 7, where the active material layer 3 is not coated on either of the pair of main surfaces 5 and 6. Furthermore, in the strip, in the width direction from the long side 8 of the current collector 2 to the coated end 10 containing the active material layer 3, a coated area 11 is formed where at least one of the pair of main surfaces 5 and 6 of the current collector 2 is coated with the active material layer 3. In the manufacture of electrode structure 1, after the active material layer 3 is coated onto the current collector 2, the active material layer 3 (slurry) coated on the surface of the current collector 2 is dried.

[0033] Furthermore, in a battery using an electrode formed from the electrode structure 1, it is necessary to form a relatively large width dimension b of the uncoated region 12 in the width direction within the strip. In one example, when the width dimension b of the uncoated region 12 in the width direction of the strip (current collector 2) becomes greater than 25 mm, an active material layer 3 is coated on the current collector 2. In this case, the width dimension b of the uncoated region 12 in the width direction of the manufactured electrode structure 1 is larger than 25 mm. However, even when the width dimension b of the uncoated region 12 in the width direction of the strip becomes greater than 25 mm, the size of the coated region 11 in the width direction is still larger than the width dimension b of the uncoated region 12 in the width direction.

[0034] Figure 3 This illustrates an example of a manufacturing apparatus 15 for manufacturing electrode structure 1. Figure 3 The diagram shows the process of drying the active material layer 3 applied to the current collector 2 during the manufacture of the electrode structure 1. Figure 3One example of the manufacturing apparatus 15 includes a conveying unit 16. In the conveying unit 16, a strip 1A, after an active material layer 3 has been coated on a current collector 2 and the coated active material layer 3 has been dried, is conveyed. In the conveying unit 16, a conveying direction (indicated by arrow F1) and a width direction intersecting (orthogonal or approximately orthogonal) the conveying direction are defined. Figure 3 In the conveying section 16, the direction orthogonal or approximately orthogonal to the paper surface is the width direction. Furthermore, in the conveying section 16, the side conveying the strip 1A is designated as the downstream side, and the side opposite to the conveying strip 1A is designated as the upstream side. In the conveying section 16, the strip 1A is conveyed with its length direction along the conveying direction and its width direction along the width direction of the conveying section 16. Therefore, in the conveying section 16, the thickness direction of the strip 1A intersects (or is orthogonal or approximately orthogonal to) both the conveying direction and the width direction of the conveying section 16.

[0035] Figure 3 One example of the manufacturing apparatus 15 includes a rolling section 21, a drawing section 22, an elongation section 23, a holding section 24, and a winding section 25. In the manufacturing apparatus 15, a strip 1A containing an active material layer 3, after drying, is conveyed into the rolling section 21. Then, the strip 1A passes through the elongation section 23, the holding section 24, and the drawing section 22 in sequence from the rolling section 21 and is conveyed to the winding section 25. By performing the following processes based on the rolling section 21, the elongation section 23, the holding section 24, and the drawing section 22 on the conveyed strip 1A, an electrode structure 1 is formed. The winding section 25 winds the conveyed strip 1A, i.e., the formed electrode structure 1. Figure 3 In one example, the winding section 25 includes a winding spool 26, and the electrode structure 1 (strip 1A) is wound in a cylindrical shape around the winding spool 26. Additionally, in Figure 3 In one example, the strip 1A is guided from the upstream side to the downstream side by three guide rollers (rollers) 27A, 27B, and 27C between the rolling section 21 and the holding section 24 of the conveying section 16. Additionally, the strip 1A is guided from the upstream side to the downstream side by guide roller 28 between the pulling section 22 and the winding section 25. The guide rollers 27A to 27C and 28 are formed of metals such as iron and stainless steel, for example.

[0036] The rolling section 21 rolls the active material layer 3 in the conveyed strip 1A using a rolling mill or the like. The rolling section 21 includes a pair of pressure rollers 31 and 32, which are formed of metals such as iron and stainless steel, respectively. The pressure roller 31 presses the active material layer 3 from one side of the strip 1A in the thickness direction, while the pressure roller 32 presses the active material layer 3 from the opposite side of the strip 1A in the thickness direction. Thus, the active material layer 3 is sandwiched between the pressure rollers 31 and 32 in the thickness direction of the strip 1A, and pressure (pressing) from the strip 1A in the thickness direction is applied to the active material layer 3. At this time, with the active material layer 3 coated on both sides of the current collector 2, the active material layer 3 is pressed while the pressure rollers 31 and 32 are respectively in contact with the active material layer 3. Furthermore, when the active material layer 3 is only coated on one side of the current collector 2, the active material layer 3 is pressed while one of the pressure rollers 31 and 32 is in contact with the active material layer 3 and the other of the pressure rollers 31 and 32 is in contact with the coating area 11 of the current collector 2. Due to the pressure from the pressure rollers 31 and 32, the active material layer 3 is compressed in the thickness direction of the strip 1A and stretched in the length direction of the strip 1A.

[0037] Furthermore, the rolling pressure applied to the active material layer 3 is also applied to at least one of the pair of main surfaces 5 and 6 of the current collector 2 in the coating area 11 where the active material layer 3 is applied. Therefore, in the coating area 11, the current collector 2 is elongated along its length due to the rolling pressure of the active material layer 3. On the other hand, the pressure rollers 31 and 32 do not apply the pressure generated by the rolling of the active material layer 3 to the uncoated area 12 of the current collector 2. Therefore, in the rolling of the active material layer 3, the uncoated area 12 of the current collector 2 is not elongated along its length. As described above, since the current collector 2 is elongated along its length only in the coating area 11, the conveyed strip 1A (current collector 2) is bent in a bent-in state on the side where the uncoated area 12 is located due to the rolling of the active material layer 3.

[0038] In this embodiment, the bending of the strip 1A (current collector 2) caused by rolling of the active material layer 3 is corrected by the pulling part 22 and the elongating part 23. The pulling part 22 is disposed downstream of the conveying part 16 relative to the rolling part 21, and pulls the strip 1A downstream. That is, the pulling part 22 pulls the strip 1A toward the side where the winding part 25 is located. The pulling part 22 includes a pair of pulling rollers 35 and 36. The pulling rollers 35 and 36 are formed of rubber, for example, and the coefficient of friction of the pulling rollers 35 and 36 is greater than that of the guide rollers 27A-27C, 28 and the pressure rollers 31 and 32.

[0039] In the pulling section 22, the pulling roller 35 abuts against the strip 1A from one side in the thickness direction, and the pulling roller 36 abuts against the strip 1A from the side opposite to the pulling roller 35 in the thickness direction. Thus, in the pulling section 22, with the strip 1A held between the pulling rollers 35 and 36, the strip 1A is pulled downstream of the conveying section 16. By being pulled downstream by the pulling section 22, tension in the length direction is applied to the strip 1A (current collector 2) between the pulling section 22 and the rolling section 21. Therefore, the strip 1A, with tension applied in the length direction, is conveyed via guide rollers 27A to 27C between the pulling section 22 and the rolling section 21.

[0040] In the conveying section 16, an elongation section 23 and a holding section 24 are provided between the rolling section 21 and the drawing section 22, with the elongation section 23 positioned between the rolling section 21 and the holding section 24. Figure 3 In one example, the elongated portion 23 is formed by guide roller 27C. However, in the following description, it is assumed that the elongated portion 23 is formed by guide roller 27C, but it can also be formed by any one of guide rollers 27A or 27B. The elongated portion 23 can be formed by a roller such as a guide roller for conveying the strip 1A, located between the rolling section 21 and the drawing section 22. In either case, the configuration of the elongated portion 23 and the processing performed on it are the same as when the elongated portion 23 is formed by guide roller 27C.

[0041] Figure 4 This is an example of the structure of the elongated part 23. Figure 4 The strip 1A conveyed in the conveying unit 16 is shown in a cross-section orthogonal or substantially orthogonal to the conveying direction in the conveying unit 16. Figure 4 In one example, the elongation section 23 includes a guide roller 27C, which has a rotation axis (central axis) R. The guide roller 27C can rotate around the rotation axis R. The guide roller 27C has axial directions along the rotation axis R and circumferential directions about the rotation axis R. In the conveying section 16, the strip 1A is conveyed with the rotation axis R of the guide roller 27C aligned with the width direction of the strip 1A. Therefore, the axial direction of the guide roller 27C is aligned with or approximately aligned with the width direction of the conveying section 16.

[0042] The elongated portion 23 includes a protrusion 37 formed on the outer periphery of the guide roller 27C. The protrusion 37 protrudes outward from the outer periphery of the guide roller 27C. Furthermore, the protrusion 37 is formed throughout the entire circumference of the guide roller 27C (the direction around the rotation axis R). The protrusion 37 is formed at one end of the guide roller 27C on the axially upward side. Additionally, in… Figure 4 In the diagram, guide roller 27C is shown in a cross section that is parallel or substantially parallel to the axial direction (rotation axis R).

[0043] While the strip 1A is being conveyed via the guide roller 27C, the protrusion 37 is positioned on the side of the long side 7 relative to the coating end 10 containing the active material layer 3 in the width direction of the strip 1A. That is, in the axial direction of the guide roller 27C, the protrusion 37 is positioned on the side of the uncoated area 12 protruding relative to the coating end 10 containing the active material layer 3. The protrusion 37, which applies tension in the length direction to the strip 1A being pulled 22, abuts against the uncoated area 12 of the current collector 2 from the thickness direction side and presses the uncoated area 12 from the thickness direction side. By being pressed by the protrusion 37 under tension, the current collector 2 is stretched along the length direction in the uncoated area 12 by the pressure from the protrusion 37.

[0044] When the strip 1A is being conveyed via the elongation section 23, as described above, the protrusion 37, in the width direction of the strip 1A, is located on the side protruding from the uncoated area 12 relative to the coated end 10 containing the active material layer 3. Therefore, the protrusion 37 does not abut against the coated area 11 containing the active material layer 3 and the current collector 2, and does not press against the coated area 11 of the current collector 2. Therefore, in the elongation section 23, the coated area 11 of the current collector 2 is not elongated along the length direction.

[0045] As described above, in this embodiment, when tension is applied to the strip 1A (current collector 2) in the length direction, the protrusion 37 presses only on the uncoated area 12, thereby stretching the current collector 2 in the length direction only in the uncoated area 12. By stretching the current collector 2 in the length direction only in the uncoated area 12, the aforementioned bending caused by the rolling of the active material layer 3 is corrected. Furthermore, when the active material layer 3 is coated only on one of the pair of main surfaces 5 and 6 in the coated area 11, the protrusion 37 presses on the uncoated area 12 from the side facing the main surface (the corresponding one of 5 and 6) coated with the active material layer 3 in the thickness direction of the strip 1A.

[0046] Figures 5 to 7 This is an example of the structure of part 24. Figure 5 The strip 1A conveyed in the conveying unit 16 is shown in a cross-section orthogonal or substantially orthogonal to the conveying direction in the conveying unit 16. Figure 6 The image shows the state viewed from the intersection of the conveying direction and the width direction of the conveying section 16, while the strip 1A is shown from the thickness direction. Figure 7 The strip 1A is shown in a cross section that is orthogonal or substantially orthogonal to the width direction of the conveying section 16 and passes through the uncoated area 12.

[0047] like Figures 5 to 7 As shown, the holding section 24 includes a pair of holding members 41 and 42. The holding members 41 and 42 are not misaligned or substantially misaligned relative to each other in the conveying direction and the width direction of the conveying section 16. Furthermore, when the strip 1A is being conveyed via the holding section 24, the pair of holding members 41 and 42 are positioned opposite each other, sandwiching the uncoated area 12 of the current collector 2 between them. In the holding section 24, the holding member (first holding member) 41 contacts the uncoated area 12 from one side in the thickness direction of the strip 1A. Moreover, the holding member (second holding member) 42 contacts the uncoated area 12 from the side opposite to the holding member 41 in the thickness direction of the strip 1A. That is, for the tensioned strip 1A, the pair of holding members 41 and 42 contact the uncoated area 12 of the current collector 2 from opposite sides in the thickness direction of the strip 1A. Thus, in the retaining part 24, the uncoated area 12 is retained between a pair of retaining members 41 and 42.

[0048] The retaining components 41 and 42 are, for example, formed of polyethylene. The materials forming the retaining components 41 and 42 are softer than the materials forming the pressure rollers 31 and 32 and the guide rollers 27A-27C and 27C, 28, such as iron and stainless steel. The materials forming the retaining components 41 and 42 can be softer or harder than the materials forming the pull rollers 35 and 36. Furthermore, the softness of the materials forming the retaining components 41 and 42 can be the same as the softness of the materials forming the pull rollers 35 and 36.

[0049] The coefficients of friction of retaining components 41 and 42 are smaller than those of the pulling rollers 35 and 36. The coefficients of friction of retaining components 41 and 42 can be larger or smaller than those of the pressure rollers 31 and 32 and the guide rollers 27A-27C and 28. Alternatively, the coefficients of friction of retaining components 41 and 42 can be the same as or approximately the same as those of the pressure rollers 31 and 32 and the guide rollers 27A-27C and 28. In one example, the coefficient of kinetic friction of retaining components 41 and 42 is 1 or less.

[0050] Maintain contact between components 41 and 42 and the uncoated areas 12. Figures 5 to 7In one example, the holding members 41 and 42 are in contact with the uncoated area 12, respectively, covering the entire width or approximately the entire width of the strip 1A. That is, the holding members 41 and 42 are in contact with the uncoated area 12 of the current collector 2, respectively, covering the entire area from the long side 7 of the current collector 2 to the coating end 10 containing the active material layer 3 in the width direction of the strip 1A. Furthermore, when the strip 1A is being transported via the holding part 24, the holding members 41 and 42 are positioned on the side containing the long side 7 in the width direction of the strip 1A (the width direction of the transport part 16), relative to the center position of the strip 1A. Additionally, in Figures 5 to 7 In one example, components 41 and 42 are kept from contacting the active material layer 3 (coating area 11) from the thickness direction of the strip 1A.

[0051] Furthermore, the range in which the pair of retaining members 41 and 42 contact the uncoated area 12 is defined as the contact range. The dimension X of the contact range in the length direction of the strip 1A is preferably more than twice the width dimension b of the uncoated area 12 in the width direction of the strip 1A. The retaining members 41 and 42 can contact the uncoated area 12 either in a non-rotatable state or in a state in which they can rotate about a rotation axis in the width direction of the conveying section 16. However, it is preferable that the retaining members 41 and 42 are not rotatable.

[0052] In strips 1A with a width dimension b greater than 25 mm, and strips 1A with a large width dimension b of the uncoated region 12 in the width direction of the current collector 2, during the correction of the bending of the strip 1A caused by rolling of the active material layer 3 via the pulling part 22 and the elongating part 23 as described above, the elongation in the uncoated region 12 in the length direction is sometimes uneven. For example, during the correction of the bending of the strip 1A, in the uncoated region 12, compared with the part closer to the active material layer 3 (coated end 10), the elongation in the length direction is smaller in the part farther away from the active material layer 3. Because the elongation in the length direction of the uncoated region 12 becomes uneven during the correction of the bending, the uncoated region 12 is prone to folding.

[0053] In this embodiment, between the rolling section 21 and the drawing section 22, a pair of holding members 41 and 42 contact the uncoated area 12 of the current collector 2 from opposite sides in the thickness direction of the strip 1A, thereby holding the uncoated area 12 between the pair of holding members 41 and 42. Therefore, in the manufacture of an electrode structure with a large width dimension b of the uncoated area 12, even if the uncoated area 12 becomes easily folded due to the rolling of the active material layer 3 and the correction of the bending of the strip 1A, the folding of the current collector 2 in the uncoated area 12 is appropriately suppressed by holding the uncoated area 12 between the pair of holding members 41 and 42.

[0054] Furthermore, by setting the contact area X of the holding members 41 and 42 in the length direction of the strip 1A to be more than twice the width b of the uncoated area 12 in the width direction of the strip 1A, the contact area between the holding members 41 and 42 and the uncoated area 12 can be increased. Therefore, the folding of the current collector 2 in the uncoated area 12 is appropriately suppressed. In addition, by adopting at least one of the configurations in which the holding members 41 and 42 are in contact with the uncoated area 12 in a non-rotatable state, and the configuration in which the holding members 41 and 42 are in contact with the uncoated area across the entire width between the long side 7 and the coating end 10 containing the active material layer 3, the folding of the current collector 2 in the uncoated area 12 is further appropriately suppressed.

[0055] By suppressing the folding of the current collector 2 in the uncoated area 12, damage to the current collector 2 is effectively prevented while the strip 1A is being conveyed downstream of the holding section 24. For example, it effectively prevents the current collector 2 from being caught in one of the pull rollers 35 or 36 of the pull section 22.

[0056] Furthermore, in this embodiment, the material forming the retaining members 41 and 42 is softer than the material forming the pressure rollers 31 and 32 and the guide rollers 27A-27C and 28. Therefore, even when the uncoated area 12 is held between the retaining members 41 and 42, damage to the uncoated area 12 caused by contact with the retaining members 41 and 42 is effectively prevented. In addition, the coefficient of friction of the retaining members 41 and 42 is smaller than that of the pull rollers 35 and 36. Therefore, even when the retaining members 41 and 42 are in contact with the uncoated area 12, the friction between the retaining members 41 and 42 and the uncoated area 12 can be appropriately reduced.

[0057] exist Figure 8 In the modified example shown, in the holding portion 24, the holding members 41 and 42 are in contact with the uncoated area 12 of the current collector 2 and with the active material layer 3, respectively. In this modified example, in the active material layer 3, the holding members 41 and 42 are in contact only with the coated end 10 and its vicinity. Figure 8 In one example, retaining components 41 and 42 are respectively with Figures 5 to 7 Similar to another example, retaining members 41 and 42 respectively contact the uncoated area 12, and are in contact with the uncoated area 12 throughout or substantially throughout the width of the strip 1A. Furthermore, since the material forming the retaining members 41 and 42 is soft, the portions of each retaining member 41 and 42 that contact the active material layer 3 are compressed along the thickness direction of the strip 1A. Figure 8 The strip 1A conveyed in the conveying section 16 is shown in a cross section that is orthogonal or approximately orthogonal to the conveying direction in the conveying section 16.

[0058] In one example, in the coating area 11, the active material layer 3 is applied only to one of the pair of main surfaces 5 and 6. Furthermore, in the holding portion 24, one of the holding members 41 and 42 contacts the uncoated area 12 of the current collector 2 and also contacts the active material layer 3. In the active material layer 3, one of the holding members 41 and 42 contacts only the coating end 10 and its vicinity. The other holding member 41 and 42 contacts the uncoated area 12 of the current collector 2 and, on the main surface (the corresponding side of 15 and 16) where the active material layer 3 is not applied, contacts the coating area 11. In the coating area 11, the other holding member 41 and 42 contacts only the portion closer to the uncoated area 12.

[0059] In any of the above-described modifications, the pair of retaining members 41 and 42 contact the uncoated region 12 of the current collector 2 from opposite sides in the thickness direction of the strip 1A, and hold the uncoated region 12 between the pair of retaining members 41 and 42. Therefore, in any modification, the same function and effect as in the above-described embodiments are achieved. That is, even if the width dimension b of the uncoated region 12 increases, after rolling with the active material layer 3 and correcting the bending of the strip 1A, the folding of the uncoated region 12 is appropriately suppressed.

[0060] (Verification related to implementation methods, etc.)

[0061] In addition, verification related to the above-described embodiments was performed. The verification will be described below. In the verification, an active material layer was coated onto the surface of the current collector to form a strip. Aluminum foil was used as the current collector. Furthermore, in the coating onto the surface of the current collector, a slurry was prepared by suspending the active material, conductive agent, and binder in pure water. As the active material, niobium titanium oxide having a composition represented by TiNb2O7 was prepared. As the conductive agent, acetylene black (AB) was prepared, and as the binder, carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) were prepared. Furthermore, pure water, used as a solvent, was added and mixed in a mixing ratio of 95% by mass of TiNb2O7, 2% by mass of AB, 1.5% by mass of CMC, and 1.5% by mass of SBR. The resulting mixture was then dispersed to obtain a slurry. The adjusted slurry was then coated onto the surface of the current collector. At this time, no slurry was applied to one of the pair of long sides of the current collector and its vicinity. Thus, in the strip, coated areas with active material layers coated on both sides of a pair of main surfaces, and uncoated areas without active material layers coated on either side of the pair of main surfaces are formed. The uncoated areas are formed in the current collector on one of the pair of long sides and in its vicinity. Furthermore, the width dimension b of the uncoated areas in the width direction of the strip is formed to be 30 mm.

[0062] In the verification, after forming the strip as described above, the active material layer (slurry) coated on the surface of the current collector was dried. Furthermore, in conjunction with... Figure 3 In a similar conveying section, as in the embodiments described above, a strip is conveyed. Furthermore, through... Figure 3 In a similar rolling section, the layer containing the active material is rolled in a conveyed strip using a roller press. The pressure rollers of the rolling section are formed of die steel. Additionally, downstream of the rolling section, a process is performed using a roller press... Figure 3 An identical pulling section pulls the strip downstream. This applies a length-direction tension to the strip between the pulling section and the rolling section. The pulling roller of the pulling section is made of rubber.

[0063] Additionally, during the verification, in the equivalent of Figure 3In one example, the guide roller 27C has a protrusion on its outer peripheral surface that is identical to the protrusion 37. Both the protrusion and the roller forming the protrusion on its outer peripheral surface are made of stainless steel. Furthermore, as in the embodiments described above, for a strip under tension, the protrusion presses down on the uncoated area of ​​the current collector, causing the uncoated area to elongate along its length. In verification, the occurrence of folding in the uncoated area was observed downstream of the roller where the uncoated area was elongated by the protrusion. The occurrence of folding in the uncoated area was observed under the conditions of Example 1, Example 2, and Comparative Example 1, as described below. In Example 1, Example 2, and Comparative Example 1, the pressure (pressing) pressing the active material layer in the rolling section, the pulling force pulling the strip downstream in the drawing section, and the protrusion elongating the uncoated area were all set to be the same.

[0064] In Embodiment 1, a retaining portion, identical to the retaining portion 24 described in the embodiments, is provided between the roller that elongates the uncoated area by the protrusions and the pulling portion. In the retaining portion, a pair of retaining members are formed of polyethylene. Furthermore, since the contact range between the pair of retaining members and the uncoated area is defined, the dimension X of the contact range in the length direction of the strip is set to 1 times the width dimension b of the uncoated area (30 mm). In the retaining portion, each retaining member contacts the uncoated area in a non-rotating state. Additionally, each retaining member contacts the uncoated area across the entire width of the uncoated area between the long side and the coating end containing the active material layer.

[0065] In Embodiment 2, a retaining portion is also provided between the roller that elongates the uncoated area via the protrusion and the pulling portion. However, in Embodiment 2, the contact range dimension X of the retaining member in the length direction of the strip is set to twice the width dimension b of the uncoated area (60 mm). In Embodiment 2, except for changing the contact range dimension X as described above, the conditions are the same as in Embodiment 1. Furthermore, in Comparative Example 1, no retaining portion is provided. That is, a pair of retaining members are not provided.

[0066] In Comparative Example 1, a fold occurred in the uncoated area at a position 1m downstream from the roller extending the uncoated area. Furthermore, in Example 1, a fold occurred in the uncoated area at a position 200m downstream from the roller extending the uncoated area. Moreover, in Example 2, no fold occurred in the uncoated area even at a position 400m downstream from the roller extending the uncoated area.

[0067] Based on the above verification, it has been confirmed that by holding the uncoated area between a pair of retaining members, the occurrence of folding in the uncoated area can be appropriately suppressed after rolling with an active material layer and correction of the strip's bending. Furthermore, it has been confirmed that by setting the contact range dimension X of the retaining members in the length direction of the strip to more than twice the width dimension b, the occurrence of folding in the uncoated area can be further appropriately suppressed.

[0068] According to at least one of the above embodiments or examples, tension in the length direction is applied to the strip between the rolling section that rolls the active material layer and the drawing section that draws the strip. Furthermore, between the rolling section and the drawing section, a pair of holding members are brought into contact with the uncoated area of ​​the current collector from opposite sides relative to each other in the thickness direction of the strip, and the uncoated area is held between the pair of holding members. Thus, a method and apparatus for manufacturing an electrode structure can be provided that appropriately suppresses folding of the uncoated area even if the width of the uncoated area increases, after rolling the active material layer and correcting the bending of the strip.

[0069] Furthermore, the above-described implementation methods can be summarized as the following technical solutions.

[0070] Technical Solution 1

[0071] A method for manufacturing an electrode structure, comprising:

[0072] The strip is conveyed, in which an active material layer is coated on the surface of a current collector, and in the current collector, an uncoated area without an active material layer is formed on one of a pair of long sides along the length direction and in its vicinity.

[0073] The active material layer is rolled in the conveyed strip.

[0074] Downstream of the rolling section where the active material layer is rolled, the strip is pulled downstream, thereby applying tension in the length direction to the strip between the pulling section and the rolling section; and

[0075] Between the rolling section and the drawing section, for the strip under tension, a pair of holding members contact the uncoated area of ​​the current collector from opposite sides in the thickness direction of the strip, thereby holding the uncoated area between the pair of holding members.

[0076] Technical Solution 2

[0077] In the manufacturing method of technical solution 1,

[0078] When the contact range of the pair of retaining members in contact with the uncoated area of ​​the current collector is defined, the size of the contact range in the length direction of the strip is more than twice the width of the uncoated area in the width direction of the strip.

[0079] Technical Solution 3

[0080] In the manufacturing method of technical solution 1,

[0081] The pair of retaining components are respectively in contact with the uncoated area of ​​the current collector in a non-rotating state.

[0082] Technical Solution 4

[0083] In the manufacturing method of technical solution 1,

[0084] The pair of retaining members respectively contact the uncoated area across the entire width of the strip, extending from one of the pair of long sides to the coated end containing the active substance layer.

[0085] Technical Solution 5

[0086] In the manufacturing method of technical solution 1,

[0087] In the rolling section, the active material layer is pressed from both sides of the strip in the thickness direction by clamping the active material layer between a pair of pressure rollers.

[0088] The material forming the retaining component is softer than the material forming the pressure roller.

[0089] Technical Solution 6

[0090] In the manufacturing method of technical solution 1,

[0091] In the pulling section, with the strip held between a pair of pulling rollers, the strip is pulled downstream.

[0092] The coefficient of friction of the retaining component is smaller than that of the pulling roller.

[0093] Technical Solution 7

[0094] In any of the manufacturing methods of technical solutions 1 to 6, the following features are also included:

[0095] By utilizing the protrusions extending outward from the outer periphery of the roller between the rolling section and the pair of holding members, the uncoated area of ​​the current collector is pressed against the strip under tension, thereby elongating the uncoated area along the length direction.

[0096] Technical Solution 8

[0097] In any of the manufacturing methods in technical solutions 1 to 6,

[0098] During the application of the active material layer to the surface of the current collector, the active material layer is applied to the current collector when the width dimension of the uncoated area in the width direction of the strip becomes greater than 25 mm.

[0099] Technical Solution 9

[0100] An apparatus for manufacturing an electrode structure, comprising:

[0101] The conveying unit conveys a strip in which an active material layer is coated on the surface of a current collector, and in the current collector, an uncoated area is formed on one of a pair of long sides along the length direction and in its vicinity;

[0102] The rolling section rolls the active material layer in the strip conveyed by the conveying section;

[0103] A pulling section, downstream of the rolling section, applies tension in the length direction to the strip by pulling the strip downstream; and

[0104] The holding part includes a pair of holding members and is disposed between the rolling part and the pulling part. The holding part holds the uncoated area between the pair of holding members by having the pair of holding members contact the uncoated area of ​​the current collector from opposite sides in the thickness direction of the strip.

[0105] While several embodiments of the invention have been described, these embodiments are provided as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, as well as within the scope of the claims and their equivalents.

Claims

1. A method for manufacturing an electrode structure, comprising: The strip is conveyed, in which an active material layer is coated on the surface of a current collector, and in the current collector, an uncoated area without an active material layer is formed on one of a pair of long sides along the length direction and in its vicinity. The active material layer is rolled in the conveyed strip. Downstream of the rolling section where the active material layer is rolled, the strip is pulled downstream, thereby applying tension toward the length direction to the strip between the pulling section and the rolling section. By utilizing the protrusions extending outward from the outer periphery of the roller between the rolling section and the drawing section, the uncoated area of ​​the current collector is pressed against the strip under the applied tension, thereby elongating the uncoated area along the length direction; as well as Between the roller and the pulling part, for the strip that is subjected to the tension and whose uncoated area is stretched by the protrusion of the roller, a pair of holding members contact the uncoated area of ​​the current collector from opposite sides in the thickness direction of the strip, thereby holding the uncoated area between the pair of holding members.

2. The manufacturing method as described in claim 1, When the contact range of the pair of retaining members in contact with the uncoated area of ​​the current collector is defined, the size of the contact range in the length direction of the strip is more than twice the width of the uncoated area in the width direction of the strip.

3. The manufacturing method as described in claim 1, The pair of retaining components are respectively in contact with the uncoated area of ​​the current collector in a non-rotating state.

4. The manufacturing method as described in claim 1, The pair of retaining members respectively contact the uncoated area across the entire width of the strip, extending from one of the pair of long sides to the coated end containing the active substance layer.

5. The manufacturing method as described in claim 1, In the rolling section, the active material layer is pressed from both sides of the strip in the thickness direction by clamping the active material layer between a pair of pressure rollers. The material forming the retaining component is softer than the material forming the pressure roller.

6. The manufacturing method as described in claim 1, In the pulling section, with the strip held between a pair of pulling rollers, the strip is pulled downstream. The coefficient of friction of the retaining component is smaller than that of the pulling roller.

7. The manufacturing method according to any one of claims 1 to 6, During the application of the active material layer to the surface of the current collector, the active material layer is applied to the current collector when the width dimension of the uncoated area in the width direction of the strip becomes greater than 25 mm.

8. An apparatus for manufacturing an electrode structure, comprising: The conveying unit conveys a strip in which an active material layer is coated on the surface of a current collector, and in the current collector, an uncoated area is formed on one of a pair of long sides along the length direction and in its vicinity; The rolling section rolls the active material layer in the strip conveyed by the conveying section; The pulling section, located downstream of the rolling section, applies tension to the strip in the length direction by pulling the strip downstream. The elongation section includes a roller with a protrusion extending outwards, and by using the protrusion of the roller between the rolling section and the drawing section, the uncoated area of ​​the current collector is pressed against the strip under tension, thereby elongating the uncoated area along the length direction. as well as A holding portion, comprising a pair of holding members, is disposed between the elongation portion and the pulling portion. For a strip that has been subjected to tension and whose uncoated area has been elongated by the elongation portion, the holding portion holds the uncoated area between the pair of holding members by having the pair of holding members contact the uncoated area of ​​the current collector from opposite sides relative to each other in the thickness direction of the strip.

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