Roller pressing device and method for manufacturing compacted strip electrode plate

Abstract

The present invention provides a rolling device capable of suppressing wrinkles in the inactive material portion when rolling a strip electrode plate having an active material portion and an inactive material portion formed in strip shape, respectively, and a method for manufacturing the strip electrode plate after compaction. The rolling device (100) comprises a first squeezing roller (110) and a second squeezing roller (120). The first squeezing roller (110) comprises a first contact portion (111) in contact with the active material portion (11) of the strip electrode plate (1Z), and a second contact portion (112) in contact with the inactive material portion (12) of the strip electrode plate (1Z). The second contact portion (112) has a friction force enhancement form in which the friction force (F2) generated between the second contact portion (112) and the inactive material portion (12) of the strip electrode plate (1Z) is greater than the imaginary friction force (F1) generated when the first contact portion (111) is assumed to contact the inactive material portion (12) of the strip electrode plate (1Z).

Description

Technical Field

[0001] The present invention relates to a roll pressing device for rolling a strip electrode plate to densify an active material layer, and a method for manufacturing a densified strip electrode plate for rolling a strip electrode plate to densify an active material layer. Background Art

[0002] As an electrode plate for lithium-ion secondary batteries, there is known a strip-shaped electrode plate having a strip-shaped active material layer compressed and compacted in the thickness direction on a strip-shaped collector foil. Figure 6 As shown, there is a compacted strip electrode plate 901, which has a central portion in the width direction FH as a strip-shaped active material portion 911 having compacted active material layers 905 and 906 in the thickness direction GH, and has two side portions in the width direction FH as strip-shaped inactive material portions 912 which do not have compacted active material layers 905 and 906 in the thickness direction GH.

[0003] The compacted strip electrode plate 901 is manufactured, for example, by the following method: first, the undried active material layers 905X and 906X are formed in a strip shape at the center of the strip collector foil 3 in the width direction FH, and then the undried active material layers 905X and 906X are heated and dried to form active material layers 905Z and 906Z.

[0004] Next, the strip electrode plate 901Z is conveyed in the longitudinal direction EH and rolled to compact the active material layers 905Z and 906Z in the thickness direction GH, thereby forming compacted active material layers 905 and 906. In this way, the compacted strip electrode plate 901 is formed. In addition, as a related prior art, for example, Patent Document 1 can be cited.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-228349

[0006] However, when the above-mentioned strip electrode plate 901Z is rolled, sometimes oblique linear wrinkles SW extending obliquely from the inner side and upstream side EUH in the width direction FH toward the outer side and downstream side EDH in the width direction FH are repeatedly generated in the inactive material portion 912, especially near the boundary with the active material portion 911.

[0007] The reason why such oblique wrinkles SW are generated can be considered to be as follows. That is, in the compacted strip electrode plate 901 after rolling (after the rolling process), the active material portion 911 is extended in the long side direction EH, and the thickness of the inactive material portion 912 is thinner than the active material portion 911, and is hardly squeezed, so it is hardly extended. Therefore, the tension applied to the compacted strip electrode plate 901 after rolling toward the downstream side EDH is hardly applied to the active material portion 911 but to the inactive material portion 912. In this way, if a large tension toward the downstream is applied to the inactive material portion 912, its reaction force is concentrated near the boundary with the active material portion 911 on the inner side of the width direction FH in the inactive material portion 912. Therefore, it can be considered that the shape caused by the reaction force concentrated near this boundary, that is, the oblique wrinkles SW, are generated. Summary of the invention

[0008] The present invention is completed in view of the current situation, and provides a rolling device that can suppress the generation of wrinkles in the inactive material portion when rolling a strip electrode plate having an active material portion and an inactive material portion respectively formed in a strip shape, and a method for manufacturing a compacted strip electrode plate that can suppress the generation of wrinkles in the inactive material portion when rolling the above-mentioned strip electrode plate.

[0009] One solution of the present invention for solving the above-mentioned problems is a rolling device, which is a rolling device that rolls the strip electrode plate while conveying it in the above-mentioned long side direction to compact the above-mentioned active material layer, the above-mentioned strip electrode plate has a strip-shaped collector foil and a strip-shaped active material layer extending on the above-mentioned collector foil along the long side direction of the above-mentioned collector foil, the strip electrode plate has: an active material portion, which is in the shape of a strip extending in the above-mentioned long side direction and has the above-mentioned active material layer in the thickness direction of the above-mentioned collector foil; and an inactive material portion, which is in the shape of a strip extending in the above-mentioned long side direction, is parallel to the above-mentioned active material portion in the width direction of the above-mentioned collector foil, does not have the above-mentioned active material layer in the above-mentioned thickness direction, and is thicker than the above-mentioned active material portion. The material portion is thin, wherein the above-mentioned rolling device includes a first extrusion roller and a second extrusion roller arranged in parallel with a roller gap therebetween, the above-mentioned first extrusion roller having: a first contact portion in contact with the above-mentioned active material portion of the above-mentioned strip electrode plate; and a second contact portion in contact with the above-mentioned inactive material portion of the above-mentioned strip electrode plate, the above-mentioned second contact portion of the above-mentioned first extrusion roller has a friction force increasing form, and the friction force increasing form is a form different from the above-mentioned first contact portion, and the friction force increasing form is a form in which the friction force F2 generated between the above-mentioned inactive material portion of the above-mentioned strip electrode plate is greater than the hypothetical friction force F1 (F2>F1) generated when the above-mentioned first contact portion of the above-mentioned first extrusion roller is assumed to contact the above-mentioned inactive material portion of the above-mentioned strip electrode plate.

[0010] In the above-mentioned rolling device, the second contact portion of the first extrusion roller that contacts the inactive material portion of the strip electrode plate is different from the first contact portion that contacts the active material portion of the strip electrode plate, and has a friction force increase form in which the friction force F2 generated between the inactive material portion is greater than the imaginary friction force F1 generated when the inactive material portion is assumed to be in contact with the first contact portion. As a result, when the strip electrode plate is rolled, a relatively large friction force F2 is generated between the second contact portion of the first extrusion roller and the inactive material portion of the strip electrode plate. The friction force F2 disperses the tension applied to the inactive material portion toward the downstream, so the reaction force generated near the boundary with the active material portion in the inactive material portion becomes smaller. Therefore, it is possible to suppress the generation of oblique wrinkles in the inactive material portion centered near the boundary.

[0011] In addition, as a "strip electrode plate", for example, a strip electrode plate having strip-shaped inactive material portions arranged side by side on both sides of a strip-shaped active material portion in the width direction as described above can be cited. Alternatively, a strip electrode plate having a plurality of strip-shaped active material portions and a plurality of strip-shaped inactive material portions alternately arranged side by side in the width direction can also be cited.

[0012] Examples of the “inactive material portion” include an inactive material portion consisting of only a collector foil and an inactive material portion in which a protective layer thinner than the active material layer is formed on the collector foil.

[0013] Preferably, in the above-mentioned roll pressing device, the second contact portion of the first pressing roller has the friction force increasing form having a surface roughness greater than a surface roughness of the first contact portion.

[0014] Preferably, in the above-mentioned roll pressing device, the second contact portion of the first pressing roll has the above-mentioned friction force increasing form having a roll diameter larger than a roll diameter of the first contact portion.

[0015] In addition, another scheme is a method for manufacturing a strip electrode plate that has been compacted and has a strip-shaped collector foil and a strip-shaped active material layer that has been compacted in the thickness direction of the above-mentioned collector foil, wherein the method for manufacturing the above-mentioned strip electrode plate that has been compacted and has been compacted comprises: an electrode plate forming step, forming a strip electrode plate, the strip electrode plate comprising the above-mentioned collector foil and a strip-shaped active material layer extending on the above-mentioned collector foil along the long side direction of the above-mentioned collector foil, the strip electrode plate having an active material portion and an inactive material portion, the above-mentioned active material portion being in the shape of a strip extending in the above-mentioned long side direction, having the above-mentioned active material layer in the above-mentioned thickness direction, the above-mentioned inactive material portion being in the shape of a strip extending in the above-mentioned long side direction, being arranged side by side with the above-mentioned active material portion in the width direction of the above-mentioned collector foil, having no above-mentioned active material layer in the above-mentioned thickness direction, and having a thickness thinner than the above-mentioned active material portion; and an extrusion step, conveying the above-mentioned strip electrode plate in the above-mentioned long side direction while passing The first extrusion roller and the second extrusion roller which are arranged in parallel with each other with a roller gap therebetween are used to roll the strip electrode plate having the above-mentioned completed compaction and the active material layer, wherein the first extrusion roller comprises: a first contact portion which contacts the above-mentioned active material portion of the strip electrode plate; and a second contact portion which contacts the above-mentioned inactive material portion of the strip electrode plate, wherein the second contact portion of the first extrusion roller has a friction force increasing form which is different from the first contact portion, and wherein the friction force increasing form is a form in which the friction force F2 generated between the first extrusion roller and the inactive material portion of the strip electrode plate is greater than the hypothetical friction force F1 (F2>F1) generated when the first contact portion of the first extrusion roller is assumed to contact the inactive material portion of the strip electrode plate, and the extrusion process is performed by making the second contact portion of the first extrusion roller contact the inactive material portion of the strip electrode plate.

[0016] In the above-mentioned method for manufacturing a strip electrode plate that has been densified, the extrusion process is performed using a first extrusion roller having a friction force increasing form different from the first contact part that contacts the active material part of the strip electrode plate, and the second contact part that contacts the inactive material part of the strip electrode plate. Specifically, the second contact part of the first extrusion roller has a friction force increasing form in which the friction force F2 generated between the second contact part and the inactive material part is greater than the imaginary friction force F1 generated when the first contact part is assumed to contact the inactive material part. Thus, when the strip electrode plate is rolled, as described above, the tension applied to the inactive material part toward the downstream is dispersed by the relatively large friction force F2, so the reaction force generated near the boundary between the inactive material part and the active material part becomes smaller. Therefore, it is possible to suppress the generation of oblique wrinkles in the inactive material part centered near the boundary.

[0017] Preferably, in the above-mentioned method for manufacturing a densified strip electrode plate, the second contact portion of the first pressing roller has the friction force increasing form having a surface roughness greater than that of the first contact portion.

[0018] Preferably, in the above-mentioned method for manufacturing a densified strip electrode plate, the second contact portion of the first pressing roller has the friction force increasing configuration having a roller diameter larger than that of the first contact portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a perspective view of the densified belt-shaped electrode plate according to the first and second embodiments.

[0020] Figure 2 This is a flowchart of the method for manufacturing the densified strip electrode plate according to the first and second embodiments.

[0021] Figure 3 This is an explanatory diagram when the roll pressing device according to the first and second embodiments is viewed from the side.

[0022] Figure 4 This is an explanatory diagram of Embodiment 1 when the first squeeze roll and the second squeeze roll are viewed from the downstream side.

[0023] Figure 5 The following is an explanatory diagram of Embodiment 2, in which the first squeeze roll and the second squeeze roll are viewed from the downstream side.

[0024] Figure 6 It is a perspective view of a strip electrode plate that has been densified according to the prior art.

[0025] Description of Reference Numerals

[0026] 1…Completed compacted strip electrode plate; 1Z…Strip electrode plate; 3…Collector foil; 5…First compacted active material layer; 5Z…First active material layer; 6…Second compacted active material layer; 6Z…Second active material layer; 11…Active material portion; 12…Inactive material portion; 100…Rolling device; 110, 210…First extrusion roller; 111, 211…First contact portion; 112, 212…Second contact portion; 120…Second extrusion roller; EH…Long side direction; FH…Width direction; GH…Thickness direction; KA…Roller gap; F1…Imagined friction force; F2…Friction force; S1…Electrode plate forming process; S2…Extrusion process. DETAILED DESCRIPTION

[0027] (Implementation Method 1)

[0028] Hereinafter, a first embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 , a three-dimensional view of the compacted strip electrode plate 1 according to the first embodiment is shown. The compacted strip electrode plate 1 is used to manufacture a rectangular and sealed lithium-ion secondary battery mounted on a hybrid vehicle, a plug-in hybrid vehicle, an electric vehicle, or the like. Specifically, the compacted strip electrode plate 1 is a strip positive electrode plate used to manufacture a flat, wound or stacked electrode body constituting a battery. In addition, the long side direction EH, the width direction FH, and the thickness direction GH of the compacted strip electrode plate 1 are defined as follows: Figure 1 The directions shown are used for illustration.

[0029] The compacted strip electrode plate 1 has a collector foil 3 made of aluminum foil extending in a strip shape in the longitudinal direction EH and having a thickness of about 13 μm. On the first main surface 3a of the collector foil 3, in the region extending in the longitudinal direction EH at the center of the width direction FH, a first compacted active material layer 5 having a thickness of about 60 μm, which is compressed and compacted in the thickness direction GH, is formed in a strip shape in the longitudinal direction EH (hereinafter, also referred to as "the compacted active material layer 5"). In addition, on the second main surface 3b on the opposite side of the collector foil 3, in the region extending in the longitudinal direction EH at the center of the width direction FH, a second compacted active material layer 6 having a thickness of about 60 μm, which is compressed and compacted in the thickness direction GH, is also formed in a strip shape in the longitudinal direction EH (hereinafter, also referred to as "the compacted active material layer 6"). On the other hand, the portions of the collector foil 3 extending in the longitudinal direction EH on both sides in the width direction FH do not have the densified active material layers 5 and 6 , and the collector foil 3 is exposed in the thickness direction GH.

[0030] As described above, the compacted strip electrode plate 1 is composed of the collector foil 3 and the strip-shaped compacted active material layers 5 and 6 formed on the collector foil 3. The central portion in the width direction FH of the compacted strip electrode plate 1 is the strip-shaped active material portion 11 having the compacted active material layers 5 and 6 in the thickness direction GH. On the other hand, the two side portions in the width direction FH of the compacted strip electrode plate 1 (the portions arranged side by side on both sides of the active material portion 11 in the width direction FH) are the inactive material portions 12 which do not have the compacted active material layers 5 and 6 in the thickness direction GH and are thinner than the active material portion 11.

[0031] The compacted active material layers 5 and 6 are composed of active material particles, conductive particles, and a binder. In the first embodiment, lithium transition metal composite oxide particles, specifically lithium nickel cobalt manganese oxide particles, are used as active material particles. In addition, acetylene black (AB) particles are used as conductive particles, and polyvinylidene fluoride (PVDF) is used as a binder.

[0032] Next, a method for manufacturing the compacted strip-shaped positive electrode plate 1 will be described (see Figure 2 to Figure 4 ). First, in the "electrode plate forming step S1" (refer to Figure 2 ) to form a strip electrode plate 1Z before extrusion. The electrode plate forming step S1 sequentially comprises a "first undried layer forming step S11", a "first drying step S12", a "second undried layer forming step S13" and a "second drying step S14".

[0033] First, in the first undried layer forming step S11, the first undried active material layer 5X is formed on the first main surface 3a of the collector foil 3. Specifically, active material particles (lithium nickel cobalt manganese oxide particles in the first embodiment), conductive particles (AB particles in the first embodiment), a binder (PVDF in the first embodiment), and a dispersion medium (N-methylpyrrolidone (NMP) in the first embodiment) are mixed to obtain an active material paste in advance. In the first undried layer forming step S11, the collector foil 3 is conveyed in the longitudinal direction EH, and the active material paste is discharged to the central part of the first main surface 3a of the collector foil 3 in the width direction FH by a coating die (not shown), so that the first undried active material layer 5X is continuously formed in a strip shape on the first main surface 3a of the collector foil 3.

[0034] Next, in the first drying step S12, the strip electrode plate obtained in the first undried layer forming step S11 is transported to a drying device (not shown), and hot air is blown toward the first undried active material layer 5X to heat and dry it, thereby forming the first active material layer 5Z (hereinafter also referred to as "active material layer 5Z").

[0035] Next, in the second undried layer forming step S13 , similarly to the first undried layer forming step S11 , a second undried active material layer 6X is formed in a strip shape at the center of the second main surface 3 b on the opposite side of the collector foil 3 in the width direction FH.

[0036] Next, in the second drying step S14, similarly to the first drying step S12, hot air is blown to the second undried active material layer 6X in the strip electrode plate obtained in the second undried layer forming step S13 to heat and dry it, thereby forming a second active material layer 6Z (hereinafter, also referred to as "active material layer 6Z"). In this way, the strip electrode plate 1Z before extrusion is obtained.

[0037] The strip electrode plate 1Z is composed of a collector foil 3 and strip-shaped active material layers 5Z and 6Z. The central portion of the strip electrode plate 1Z in the width direction FH is a strip-shaped active material portion 11 having active material layers 5Z and 6Z in the thickness direction GH, and the two side portions arranged side by side on both sides of the active material portion 11 in the width direction FH are strip-shaped inactive material portions 12 that do not have active material layers 5Z and 6Z in the thickness direction GH.

[0038] Next, in the "extrusion step S2" (refer to Figure 2 ), using a roller pressing device 100 (refer to Figure 3 and Figure 4 ), the strip electrode plate 1Z formed in the electrode plate forming step S1 is conveyed in the long side direction EH, and is rolled in the thickness direction GH to compact the active material layers 5Z and 6Z respectively, thereby forming the compacted active material layers 5 and 6.

[0039] First, the roller pressing device 100 is described. The roller pressing device 100 comprises: a first squeeze roller 110 and a second squeeze roller 120, which are arranged in parallel with a roller gap KA therebetween; an upstream conveying roller 130, which is arranged on the upstream side EUH (at the position of the first squeeze roller 110 and the second squeeze roller 120) than the first squeeze roller 110 and the second squeeze roller 120. Figure 3 and the downstream conveying roller 135, disposed on the downstream side of the first extrusion roller 110 and the second extrusion roller 120 EDH (in Figure 3 The position of the middle is on the right).

[0040] The roller surfaces 110m and 120m of the first squeeze roller 110 and the second squeeze roller 120 are both made of stainless steel. A motor (not shown) is connected to each of the first squeeze roller 110 and the second squeeze roller 120. The first squeeze roller 110 is configured to be able to Figure 3 The second squeeze roller 120 is configured to rotate counterclockwise. Figure 3 In the first embodiment, the first active material layer 5Z is oriented toward Figure 3 and Figure 4 The second active material layer 6Z is oriented toward the upper side of Figure 3 and Figure 4Therefore, the first pressing roller 110 is in contact with the first active material layer 5Z of the strip electrode plate 1Z, and the second pressing roller 120 is in contact with the second active material layer 6Z of the strip electrode plate 1Z.

[0041] The upstream conveying roller 130 and the downstream conveying roller 135 are arranged closer to the roller gap KA between the first pressing roller 110 and the second pressing roller 120 so as to contact the second active material layer 6Z of the strip electrode plate 1Z. Figure 3 Thus, the first squeeze roller 110 is in contact with the strip electrode plate 1Z at an angle. In addition, the first squeeze roller 110 extends in the width direction FH (in Figure 4 The almost entire portion of the strip electrode plate 1 is in contact with the strip electrode plate 1 (refer to Figure 4 ). That is, the first squeeze roller 110 contacts not only the thicker active material portion 11 (the first active material layer 5Z) in the strip electrode plate 1Z, but also the thinner inactive material portion 12 (the collector foil 3) in the strip electrode plate 1Z. The central portion of the first squeeze roller 110 in the width direction FH that contacts the active material portion 11 of the strip electrode plate 1 is the first contact portion 111, and the two side portions in the width direction FH that contact the inactive material portion 12 of the strip electrode plate 1 are the second contact portions 112.

[0042] The second contact portion 112 of the first squeeze roller 110 has a friction force enhancement form different from that of the first contact portion 111. That is, in the first embodiment, the roller surface 111m of the first contact portion 111 is mirror-polished, and its surface roughness Ra1 (hereinafter, also referred to as "surface roughness Ra1 of the first contact portion 111") is Ra1 = about 0.1 μm. In contrast, the surface roughness Ra2 of the roller surface 112m of the second contact portion 112 (hereinafter, also referred to as "surface roughness Ra2 of the second contact portion 112") is greater than Ra1, and Ra2 is 0.2 μm or more (Ra2 = about 0.5 μm in the first embodiment). Due to the difference in surface roughness Ra1 and Ra2, the friction force F2 generated between the second contact portion 112 of the first extrusion roller 110 and the inactive material portion 12 of the strip electrode plate 1Z is greater than the hypothetical friction force F1 (F2>F1) generated when the first contact portion 111 of the first extrusion roller 110 is assumed to contact the inactive material portion 12 of the strip electrode plate 1Z.

[0043] In the extrusion step S2, the strip electrode plate 1Z is rolled by the first extrusion roller 110 and the second extrusion roller 120 to compact the active material layers 5Z and 6Z, thereby forming compacted active material layers 5 and 6. At this time, as described above, the surface roughness Ra2 of the second contact portion 112 in the first extrusion roller 110 is greater than the surface roughness Ra1 of the first contact portion 111, so a relatively large friction force F2 is generated between the inactive material portion 12 of the strip electrode plate 1 and the second contact portion 112 of the first extrusion roller 110. The friction force F2 disperses the tension applied to the inactive material portion 12 toward the downstream, so that the reaction force generated near the boundary between the inactive material portion 12 and the active material portion 11 is reduced. Therefore, it is possible to suppress the generation of oblique wrinkles in the inactive material portion 12 centered near the boundary.

[0044] In addition, it is also studied to increase the surface roughness Ra1 of the first contact portion 111 of the first squeeze roller 110 to be equal to the surface roughness Ra2 of the second contact portion 112. However, in this case, during rolling, the active material layer 5Z, 6Z is likely to adhere to the roller surface 110m of the first squeeze roller 110 (roller surface 111m of the first contact portion 111). Therefore, as described above, it is preferable to make the surface roughness Ra2 of the second contact portion 112 larger than the surface roughness Ra1 of the first contact portion 111.

[0045] As described above, in the roll pressing device 100 and the method for manufacturing the densified strip electrode plate 1, the first squeeze roller 110 is used to perform the squeeze step S2, in which the second contact portion 112 that contacts the inactive material portion 12 of the strip electrode plate 1Z is a friction force enhancement form different from the first contact portion 111 that contacts the active material portion 11 of the strip electrode plate 1Z. Specifically, the second contact portion 112 of the first squeeze roller 110 has a friction force enhancement form in which the friction force F2 generated between the second contact portion 112 and the inactive material portion 12 of the strip electrode plate 1Z is greater than the imaginary friction force F1 generated when the first contact portion 111 of the first squeeze roller 110 is assumed to contact the inactive material portion 12 of the strip electrode plate 1Z. As a result, when the strip electrode plate 1Z is rolled, the tension applied to the inactive material portion 12 toward the downstream is dispersed by the relatively large friction force F2, so that the reaction force generated near the boundary between the inactive material portion 12 and the active material portion 11 is reduced. Therefore, it is possible to suppress the occurrence of oblique wrinkles in the inactive material portion 12 centered around the vicinity of the boundary.

[0046] (Implementation Method 2)

[0047] Next, the second embodiment is described. In the first embodiment, the extrusion step S2 is performed using the first extrusion roller 110 in which the surface roughness Ra2 of the second contact portion 112 is greater than the surface roughness Ra1 of the first contact portion 111 (see Figure 4 ). In contrast, in the second embodiment, the difference is that the first extrusion roller 210 is used to make the roller diameter D2 of the second contact portion 212 of the first extrusion roller 210 larger than the roller diameter D1 of the first contact portion 211 (D2>D1) to perform the extrusion step S2 (refer to Figure 5 ).

[0048] The rolling device 200 involved in the second embodiment includes a first squeezing roller 210 in which a cylindrical squeezing roller is processed into a stepped shape. The second contact portion 212 of the first squeezing roller 210 also has a friction-enhancing form. Specifically, the first contact portion 211 of the first squeezing roller 210 that contacts the active material portion 11 of the strip electrode plate 1Z has the same form as the first contact portion 111 of the first squeezing roller 210 of the first embodiment. On the other hand, the roller diameter D2 of the second contact portion 212 of the first squeezing roller 210 that contacts the inactive material portion 12 of the strip electrode plate 1Z is formed to be 30 μm larger than the roller diameter D1 of the first contact portion 211. In addition, the portion 212t near the boundary with the first contact portion 211 of the second contact portion 212 is an inclined surface without a corner. This is to reliably prevent the inactive material portion 12 of the strip electrode plate 1Z from hitting the corner and being damaged.

[0049] In the second embodiment, the entire roller surface 210m of the first squeeze roller 210 is mirror-polished. Therefore, the surface roughness Ra1 of the roller surface 211m of the first contact portion 211 is equal to the surface roughness Ra2 of the roller surface 212m of the second contact portion 212 (Ra1=Ra2).

[0050] In this way, if the roller diameter D2 of the second contact portion 212 of the first squeeze roller 210 is made larger than the roller diameter D1 of the first contact portion 211, the friction force F2 generated between the second contact portion 112 and the inactive material portion 12 of the strip electrode plate 1Z is larger than the imaginary friction force F1 generated when the first contact portion 111 is assumed to contact the inactive material portion 12 of the strip electrode plate 1Z (F2>F1). This is because the force pressing the inactive material portion 12 to the second contact portion 112 increases, thereby increasing the friction force F2.

[0051] In the second embodiment, the pressing step S2 is performed using the roller pressing device 200 having such a first pressing roller 210. Therefore, in the second embodiment, a relatively large friction force F2 is generated between the inactive material portion 12 of the strip electrode plate 1 and the second contact portion 212 of the first pressing roller 210. The friction force F2 disperses the tension applied to the inactive material portion 12 toward the downstream, so that the reaction force generated near the boundary between the inactive material portion 12 and the active material portion 11 is reduced, thereby suppressing the generation of wrinkles in the inactive material portion 12.

[0052] As mentioned above, although the present invention has been described based on Embodiments 1 and 2, the present invention is not limited to Embodiments 1 and 2, and it is needless to say that the present invention can be applied with appropriate changes within the scope not departing from the gist thereof.

[0053] For example, in the first and second embodiments, the present invention is applied when the compacted strip electrode plate 1 is a positive electrode plate, but the present invention can also be applied when the compacted strip electrode plate 1 is a negative electrode plate.

[0054] In the second embodiment, the first squeeze roller 210 processed into a stepped shape is exemplified as the first squeeze roller whose roller diameter D2 of the second contact portion is larger than the roller diameter D1 of the first contact portion, but the present invention is not limited thereto. For example, the first squeeze roller may be a squeeze roller in which a resin tape or a metal tape is attached to a portion of the cylindrical squeeze roller that becomes the second contact portion, or a coating composed of a resin or a metal is formed to make the roller diameter D2 of the second contact portion larger than the roller diameter D1 of the first contact portion.

[0055] In the second embodiment, the surface roughness Ra1 of the first contact portion 211 of the first squeeze roller 210 is equal to the surface roughness Ra2 of the second contact portion 212. However, the surface roughness Ra2 of the second contact portion 212 may be greater than the surface roughness Ra1 of the first contact portion 211 as in the first embodiment. In this way, if the surface roughness Ra2 of the second contact portion 212 is greater than the surface roughness Ra1 of the first contact portion 211 in addition to the roller diameter D2 of the second contact portion 212 being greater than the roller diameter D1 of the first contact portion 211, the friction force F2 generated between the second contact portion 212 and the inactive material portion 12 of the strip-shaped electrode plate 1Z can be made greater than the virtual friction force F1 generated between the first contact portion 211 and the inactive material portion 12. Therefore, the generation of wrinkles in the inactive material portion 12 can be more effectively suppressed.

Claims

1. A roller pressing device (100, 200) for compacting an active material layer (5Z, 6Z) by roller pressing a strip electrode plate (1Z) while conveying it in a longitudinal direction (EH), The strip electrode plate (1Z) comprises a strip collector foil (3) and the strip active material layer (5Z, 6Z) extending on the collector foil (3) along the longitudinal direction (EH) of the collector foil (3). The strip electrode plate (1Z) has: an active material portion (11) in the form of a strip extending in the longitudinal direction (EH) and having the active material layer (5Z, 6Z) in the thickness direction (GH) of the collector foil (3); and The inactive material portion (12) is in the form of a strip extending in the longitudinal direction (EH) and is arranged side by side with the active material portion (11) in the width direction (FH) of the collector foil (3). The inactive material portion (12) does not have the active material layer (5Z, 6Z) in the thickness direction (GH) and is thinner than the active material portion (11). in, The roller pressing device (100, 200) comprises a first squeezing roller (110, 210) and a second squeezing roller (120) which are arranged in parallel with a roller gap (KA) therebetween. The first squeezing roller (110, 210) is configured to contact the strip electrode plate at an angle, and has: a first contact portion (111, 211) in contact with the active material portion (11) of the strip electrode plate (1Z); and The second contact portion (112, 212) contacts the inactive material portion (12) of the strip electrode plate (1Z). The second contact portion (112, 212) of the first squeezing roller (110, 210) has a friction-enhancing configuration. This friction force increasing form is different from the first contact portion (111, 211). The friction force increase mode is a mode in which the friction force (F2) generated between the inactive material portion (12) of the strip electrode plate (1Z) is greater than the imaginary friction force (F1) generated when the first contact portion (111, 211) of the first squeezing roller (110, 210) is assumed to contact the inactive material portion (12) of the strip electrode plate (1Z) (F2>F1), Among the first pressing roller and the second pressing roller, only the second contact portion of the first pressing roller is brought into contact with the inactive material portion of the strip electrode plate, and the active material portion of the strip electrode plate is pressed by the first contact portion of the first pressing roller and the second pressing roller.

2. The rolling device (100) according to claim 1, wherein: The second contact portion (112) of the first squeezing roller (110) has the friction force increasing form having a surface roughness (Ra2) greater than a surface roughness (Ra1) of the first contact portion (111).

3. The rolling device (200) according to claim 1 or 2, wherein: The second contact portion (212) of the first squeezing roller (210) has the friction force increasing form having a roller diameter (D2) larger than a roller diameter (D1) of the first contact portion (211).

4. A method for manufacturing a compacted strip electrode plate (1), the compacted strip electrode plate (1) comprising a strip collector foil (3) and a compacted strip active material layer (5, 6) compacted in a thickness direction (GH) of the collector foil (3), wherein: The method for manufacturing the compacted strip electrode plate (1) comprises: An electrode plate forming step (S1) is to form a strip-shaped electrode plate (1Z). The strip electrode plate (1Z) comprises the collector foil (3) and a strip-shaped active material layer (5Z, 6Z) extending on the collector foil (3) along the longitudinal direction (EH) of the collector foil (3). The strip electrode plate (1Z) comprises an active material portion (11) and an inactive material portion (12). The active material portion (11) is in the shape of a strip extending in the longitudinal direction (GH) and has the active material layer (5Z, 6Z) in the thickness direction (GH). The inactive material portion (12) is in the form of a strip extending in the longitudinal direction (EH), and is arranged side by side with the active material portion (11) in the width direction (FH) of the collector foil (3); the inactive material portion (12) does not have the active material layer (5Z, 6Z) in the thickness direction (GH), and is thinner than the active material portion (11); and The extrusion step (S2) comprises conveying the strip electrode plate (1Z) in the longitudinal direction while rolling it with a first extrusion roller (110, 210) and a second extrusion roller (120) arranged in parallel with a roller gap (KA) therebetween, thereby forming the compacted strip electrode plate (1) having the compacted active material layer (5, 6), The first squeezing roller (110, 210) is configured to contact the strip electrode plate at an angle, and has: a first contact portion (111, 211) in contact with the active material portion (11) of the strip electrode plate (1Z); and The second contact portion (112, 212) contacts the inactive material portion (12) of the strip electrode plate (1Z). The second contact portion (112, 212) of the first squeezing roller (110, 210) has a friction-enhancing configuration. This friction force increasing form is different from the first contact portion (111, 211). The friction force increase mode is a mode in which the friction force (F2) generated between the inactive material portion (12) of the strip electrode plate (1Z) is greater than the imaginary friction force (F1) generated when the first contact portion (111, 211) of the first squeezing roller (110, 210) is assumed to contact the inactive material portion (12) of the strip electrode plate (1Z) (F2>F1), In the extrusion process, among the first extrusion roller and the second extrusion roller, only the second contact portion (112, 212) of the first extrusion roller (110, 210) is brought into contact with the inactive material portion (12) of the strip electrode plate (1Z), and the active material portion of the strip electrode plate is pressed by the first contact portion of the first extrusion roller and the second extrusion roller.

5. The method for manufacturing a compacted strip electrode plate (1) according to claim 4, wherein: The second contact portion (112) of the first squeezing roller (110) has the friction force increasing form having a surface roughness (Ra2) greater than a surface roughness (Ra1) of the first contact portion (111).

6. The method for manufacturing a compacted strip electrode plate (1) according to claim 4 or 5, wherein: The second contact portion (212) of the first squeezing roller (210) has the friction force increasing form having a roller diameter (D2) larger than a roller diameter (D1) of the first contact portion (211).

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