JP2011181391A - Device for pressing electrode member for battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a press roller for a roll press device for use in manufacturing an electrode member for a battery. <P>SOLUTION: The roll press device 1 pressing the electrode member 90 with an active material 92 applied to a core material 91 includes a pair of press rollers 11, 12 each including an outer peripheral surface layer 21 and an intermediate layer 22 made of resin inside the outer peripheral surface layer 21. The outer peripheral surface layer 21 of each of the press rollers 11, 12 is harder than the intermediate layer 22, and the outer peripheral surface layer 21 and the intermediate layer 22 are deformed at and across a nip 29 part where the electrode member 90 is clamped by the pair of press rollers 11, 12. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a pressurizing device used when manufacturing an electrode member (electrode plate) for a battery.

  A lithium ion secondary battery is a non-aqueous electrolyte secondary battery in which lithium ions in an electrolyte are responsible for electrical conduction. Since the lithium ion secondary battery uses a non-aqueous electrolyte, a high voltage exceeding the electrolysis voltage of water is obtained, and the energy density is also high. In addition, lithium ion secondary batteries have a relatively high capacity and have the advantage of not causing a decrease in capacity even if they are frequently charged. Therefore, they are widely used in electronic devices such as personal computers and mobile phones.

  In general, the electrodes (electrode plate, positive electrode and negative electrode) accommodated in the lithium ion secondary battery are referred to as a core material (web, current collector, electrode foil, etc.) made of metal foil. In addition, a solution containing an active material is applied thereon. In addition to the active material, the solution is also added with a binder and, if necessary, a conductive aid and a thickener. And after apply | coating this solution, this is dried and pressed and the density of an active material is raised.

  As an example, a lithium-containing transition metal oxide (such as lithium cobaltate or lithium manganate) is mainly used as an active material for the positive electrode. The electrode to be the positive electrode is manufactured as follows. First, carbon black such as acetylene black or graphite is added to the active material as described above, and polyvinylidene fluoride is used as a binder, and N-methyl-2-pyrrolidone is added as necessary. The slurry is prepared by adding and mixing. In the coating step, this slurry is applied on a core material such as an aluminum foil by die coating or comma coating and dried. Then, in order to increase the capacity of the battery, the core material (electrode member, work) coated with the active material and dried is pressed to increase the density of the active material. Then, in a slit process, it cuts along a length direction so that a plurality of tape-like electrode materials may be formed from a core material. Finally, the positive electrode is obtained by cutting the tape electrode material into a predetermined length.

  For the negative electrode, graphite or the like that can mainly store and release lithium ions is used as an active material. The electrode to be the negative electrode is manufactured as follows. First, a slurry is prepared by mixing a rubber-based binder such as carboxymethylcellulose or styrene-butadiene rubber with the active material as described above, and adding and dispersing water as necessary. In the coating step, the slurry is applied on a core material such as copper foil by die coating or comma coating and dried. Then, in order to increase the capacity of the battery, in the pressing step, the active material is applied and the core material (electrode member, workpiece) dried is pressed to increase the density of the active material. Then, in a slit process, it cuts along a length direction so that a plurality of tape-like electrode materials may be formed from a core material. Finally, the negative electrode is obtained by cutting the tape-shaped electrode material into a predetermined length.

  Then, the positive electrode and the negative electrode obtained as described above are wound with a separator made of, for example, polyethylene interposed therebetween, and stored in a predetermined case. And a lithium ion secondary battery is obtained by inject | pouring electrolyte solution into this case and sealing.

  In Patent Document 1, a material obtained by applying an active material on a metal web and drying it in the process of manufacturing an electrode for a non-aqueous electrolyte secondary battery passes continuously between two press rolls arranged in parallel to each other. A press roll device that presses and presses is disclosed.

JP 2006-175501 (paragraph 0012)

  For the purpose of increasing the density of the active material, the electrode member (electrode plate) for the battery is pressurized with a pressurizing device (press roll device), and pressure is applied in a direction orthogonal to the active material. ing. At that time, if the core material is rolled by a press roll (press roller), the core material is stretched, and the core material undulates, which may cause the active material to peel off. Further, when the core material is rolled, residual stress is generated due to the difference in the extension between the coated portion and the uncoated portion of the active material, and when the electrode member is cut to produce an electrode sheet (tape-shaped electrode material) This may cause the electrode sheet to curl.

  In order to suppress such a problem, it is desirable to pressurize the active material using a press roll (roller) having a larger diameter that is difficult to roll the core material. However, the press roll is typically made of metal, and a press roll with a large diameter increases the manufacturing cost accordingly. Further, the press roll requires maintenance such as periodically polishing the surface, and a metal-made press roll having a large diameter requires labor and cost for maintenance. Further, in order to continue the manufacturing operation during the maintenance, it is necessary to prepare a spare metal press roll in advance, which also increases the cost.

  One embodiment of the present invention is an apparatus (pressurizing apparatus) that pressurizes an electrode member for a battery in which an active material is applied (surface) on a core material (metal web, web, current collector, electrode foil). is there. This apparatus has a pair of press rollers arranged to press with an electrode member interposed therebetween. Each of the pair of press rollers includes an outer peripheral surface layer and an intermediate layer inside the outer peripheral surface layer, the intermediate layer is made of resin, the outer peripheral surface layer is harder than the intermediate layer, and the outer peripheral surface layer and the intermediate layer sandwich the electrode member The portion is deformed, and further, the portions before and after the portion sandwiching the electrode member are also deformed.

  An elastic resin roller (resin roller) is a small-diameter roller having a large nip width due to eccentric deformation and ring deformation, and can press the electrode member in a state close to a flat plate press. For this reason, it can suppress that a core material is rolled. However, since the roller itself generates heat due to deformation of the roller, particularly ring deformation, durability tends to be lowered. Furthermore, since the active material contains a material having high hardness such as carbon or metal oxide, there is a problem that it is difficult to press with a resin having low hardness and the surface of the roller is likely to deteriorate.

  This apparatus presses an electrode member with a press roller including an inner intermediate layer made of resin, which is elastic and deforms, and an outer peripheral surface layer harder than the intermediate layer. Since the deformation of the intermediate layer is suppressed by the hard outer peripheral surface layer, the deformation of the press roller as a whole is suppressed. For this reason, the heat_generation | fever at the time of pressurizing an electrode member can be suppressed, and durability of a press roller can be improved. Further, by increasing the hardness of the outer peripheral surface layer, the active material can be easily pressed, and deterioration of the surface of the press roller can be suppressed. Further, since the press roller includes a resin-made elastic intermediate layer, the outer peripheral surface layer and the intermediate layer are deformed at a portion sandwiching the electrode member, and a nip width when pressing the active material is ensured. At the same time, the deformation of the intermediate layer in the part sandwiching the electrode member also propagates to the part before and after the part sandwiching the electrode member, so the press roller also deforms the part before and after the part sandwiching the electrode member, and the part sandwiching the electrode part The curvature becomes smaller and the radius of curvature becomes larger. Therefore, even if it is a small diameter press roller, the curvature of the part which pinches | interposes an electrode member, and the part before and behind that can be made small, while being able to pressurize an active material favorably, the rolling of a core material can be suppressed.

  In an example of a roller having an outer peripheral surface layer harder than the intermediate layer, both the outer peripheral surface layer and the intermediate layer are made of resin, and an inorganic filler is added to the surface layer of the intermediate layer to increase the hardness. Although it is possible to form the outer peripheral surface layer with a material different from that of the intermediate layer, for example, metal, the intermediate layer is basically made of the same material as the intermediate layer by adding an inorganic filler to the surface layer of the intermediate layer. Since the hard outer peripheral surface layer can be formed integrally with the outer peripheral surface layer, the outer peripheral surface layer easily deforms following the deformation of the intermediate layer.

  Moreover, it is desirable that each of the pair of press rollers includes a metal shaft layer positioned inside the intermediate layer. By controlling the thickness of the easily deformable intermediate layer, the degree of deformation (flatness) of the portion sandwiching the electrode member and the front and rear portions can be controlled.

The perspective view which shows the outline | summary of the pressurization apparatus for battery electrode members concerning one Embodiment of this invention. The figure which looked at a part of pressurization device of Drawing 1 from the side.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an outline of an apparatus for pressurizing an electrode member for a battery. FIG. 2 is a cross-sectional view showing a schematic configuration of a press roller of the pressure device of FIG.

  The pressurizing apparatus 1 is an apparatus used when manufacturing an electrode member 90 (electrode plate) for a battery. More specifically, in the pressurizing apparatus 1, an active material 92 is applied on a core material (a metal web such as aluminum or copper, a web, a current collector, an electrode foil) 91 (surface or both surfaces). It is a device that pressurizes the electrode member 90 for a battery. The pressure device 1 is a roll press device (roller press device), and applies pressure to a pair of press rollers (press rolls) 11 and 12 and one press roller 11 to the other press roller 12 side. It has a mechanism 13 and a motor 14 that rotationally drives the other press roller 12.

  An example of the pressurizing mechanism 13 is to adjust the gap between the press rollers 11 and 12 and control the force (pressure) applied to the electrode member 90 by the press rollers 11 and 12. Between the pair of press rollers 11 and 12, an electrode member 90 in which an active material 92 is applied to the core material 91 is guided through a guide (not shown) or the like by a coating device (not shown). The pair of press rollers 11 and 12 may be arranged vertically in parallel with each other, or may be arranged on the left or right or front and back. In the press rollers 11 and 12, one roller 11 or 12 may be driven by the motor 14, and both the rollers 11 and 12 may be driven by the motor 14.

  This roll press apparatus 1 increases the density of the active material 92 by mainly suppressing the elongation (extension) of the electrode member 90 and mainly compressing in the vertical direction. Mainly has the function of equal density. Further, as will be described later, it is possible to provide a function of rolling the electrode member 90 by adjusting the hardness of the outer peripheral surface layer 21 of the press rollers 11 and 12, and to control the thickness of the electrode member 90. It is also possible to have it. In addition to the roll press apparatus 1, a roll press apparatus using a metal press roller may be provided to control the thickness of the electrode member 90.

  The press rollers 11 and 12 of the roll press apparatus 1 each include an outer peripheral surface layer 21, an intermediate layer 22 inside the outer peripheral surface layer 21, and a shaft layer 23. The press rollers 11 and 12 of this example include a metal shaft layer (core metal) 23, and the core metal 23 also serves as a stainless steel shaft. The intermediate layer 22 and the outer peripheral surface layer 21 provided on the outer side (outer periphery) of the core metal 23 are made of resin, and the outer peripheral surface layer 21 is formed to be harder (higher hardness) than the intermediate layer 22. The mid layer 22 has a hardness of 92 ° to 93 ° or more in Shore D hardness.

  A resin roll having a Shore D hardness of about 92 ° is known as a calendar roll for video tape. For example, JP-A-8-263838 discloses a plurality of elastic rolls having a hardness of 93 ° or more in Shore D hardness as a calender roll for calendering a magnetic recording medium. The surface material of the elastic roll includes thermosetting resins such as aniline resins, epoxy resins, xylene resins, diallyl phthalate resins, silicone resins, urea resins, phenol resins, unsaturated polyester resins, furans. Thermoplastic resins such as acrylic resins, acrylonitrile-styrene copolymers, acrylonitrile-butadiene-styrene copolymers, acetal resins, vinylidene chloride resins, vinyl chloride resins. , Chlorinated polyether resin, styrene resin, styrene-butadiene copolymer, fiber derivative resin, vinyl carbazole resin, vinyl butyral resin, vinyl formal resin, fluorine resin, polyamide resin, polyurethane resin, polyethylene System, polycarbonate system, Vinyl acetate, polyvinyl alcohol, polybutene, polypropylene, may be mentioned methacrylic resin or the like. Furthermore, the resin is not limited to one type, and two or more types can be used in combination.

  The outer peripheral surface layer 21 is obtained by adding an inorganic filler to the surface layer of the intermediate layer 22 and further increasing the hardness to 95 ° to 96 ° or more in Shore D hardness. Examples of the inorganic filler for forming the outer peripheral surface layer 21 having high hardness in addition to the surface layer of the intermediate layer 22 include metal oxides such as alumina, iron oxide, and titanium oxide, silica, and carbon black. . These fillers are not limited to one type, but can be used in combination of two or more types. As the outer peripheral surface layer 21 with high hardness, various metals or alloys can be used.

  In the roll press apparatus 1 of this example, press rollers having a diameter of 400 mm are used as the press rollers 11 and 12, respectively. The diameters of the press rollers 11 and 12 are not limited to this.

  The press rollers 11 and 12 of the roll press apparatus 1 include an inner intermediate layer 22 that is made of resin and is elastic and deforms, and an outer peripheral surface layer 21 that is harder than the intermediate layer 22. Therefore, when the electrode member 90 is pressed between the press rollers 11 and 12, the deformation of the intermediate layer 22 is suppressed by the hard outer peripheral surface layer 21. Therefore, the press rollers 11 and 12 are deformed at a portion (nip) 29 sandwiching the electrode member 90 and a portion 28 before and after the nip 29, and the nip width 27 is widened, but the degree of ring deformation of the press rollers 11 and 12 is increased. Can be relaxed (suppressed).

  That is, the deformation of the press rollers 11 and 12 at the time of pressing the electrode member 90 includes the eccentric deformation in which the shaft layer (core metal) 23 is biased to the nip 29 by the press rollers 11 and 12, and the periphery of the core metal 23, that is, the middle. The layer 22 and the outer peripheral surface layer 21 are a combination of a ring deformation in which a portion of the nip 29 is substantially flat and deformed into an egg shape or a dharma shape as a whole.

  In contrast to eccentric deformation, ring deformation can increase the nip width 27. For this reason, in order to suppress rolling of the electrode member 90, it can be said that it is preferable that ring deformation is large. However, if the ring deformation is too large, the resistance of rotation of the press rollers 11 and 12 becomes too large, and the press rollers 11 and 12 are likely to become high temperature due to heat generation of energy loss. Therefore, the durability of the press rollers 11 and 12 is likely to decrease. On the other hand, if the ring deformation is too large, the nip width 27 becomes too wide, and it becomes difficult to apply pressure to the electrode member 90.

  On the other hand, when the eccentric deformation is the main component, the energy loss is small, so heat generation can be suppressed, and the durability of the press rollers 11 and 12 can be improved. However, it is difficult to widen the nip width 27 and it is difficult to obtain the effect of suppressing rolling.

  By providing the press rollers 11 and 12 with an intermediate layer 22 that is relatively easy to deform and an outer peripheral surface layer 21 that is harder than the intermediate layer 22 and relatively hard to deform on the outside thereof, It becomes possible to loosen the deformation in the portion 28. For this reason, heat generation in the press rollers 11 and 12 can be suppressed and the durability of the press rollers 11 and 12 can be improved while reducing the curvature in the vicinity of the nip 29 and increasing the radius of curvature to ensure the desired nip width 27. . Furthermore, it becomes easy to apply pressure to the electrode member 90 by the press rollers 11 and 12. Therefore, these press rollers 11 and 12 make it easy to apply a sufficient pressure, mainly in the vertical direction, to the electrode member 90 in order to increase the density of the active material 92 or equalize the density. Can be suppressed from rolling.

  Further, by increasing the hardness of the outer peripheral surface layer 21 of the press rollers 11 and 12, the active material 92 containing a material having a high hardness such as a metal oxide can be easily compacted. Therefore, it is possible to provide the press rollers 11 and 12 suitable for increasing the density or equal density of the active material 92. Further, damage such as abrasion of the outer peripheral surface layer 21 of the press rollers 11 and 12 can be suppressed, and the durability of the press rollers 11 and 12 can also be improved in this respect.

  In the press rollers 11 and 12, it is possible to employ a high hardness resin layer for the shaft layer 23. In order to change the thickness of the intermediate layer 22 and control the deformation in the nip 29 and the front and rear portions 28 thereof, the shaft layer 23 is preferably formed of a highly rigid material, and the shaft layer 23 is made of a metal such as stainless steel. It is more economical to form. In this example, the press rollers 11 and 12 have a diameter of about 400 mm. However, the diameter of the press roller is not limited to this, and it is more preferable to employ the metallic shaft layer 23 as the diameter increases. .

  Thus, in the roll press apparatus 1, the active material 92 is applied to the core material 91 between the upper press roller 11 and the lower press roller 12 whose gap is adjusted by the pressurizing mechanism 13. The electrode member 90 is conveyed from the front to the rear in FIG. When passing between the pair of press rollers 11 and 12, the electrode member 90 is sandwiched between the pair of press rollers 11 and 12, and the density of the active material 92 applied to the core material 91 is increased.

  At this time, in this roll press apparatus 1, the pair of press rollers 11 and 12 includes a deformable resin intermediate layer 22, and an outer periphery that deforms at the front and rear of the nip 29 in response to the deformation of the intermediate layer 22. Since the surface layer 21 is provided, a wide nip width 27 can be secured even if the diameters of the press rollers 11 and 12 are small. Therefore, the press rollers 11 and 12 can mainly apply pressure to the electrode member 90 from the direction (vertical direction, vertical direction) perpendicular to the core material 91 and the active material 92. For this reason, while being able to pressurize the active material 92 favorably, rolling of the core material 91 can be suppressed. Thereafter, the electrode member 90 in which the active material 92 is applied and pressurized to the core material 91 is cut into a predetermined length to manufacture an electrode.

  As described above, according to this roll press apparatus 1, it is possible to employ the press rollers 11 and 12 that are small in diameter and compact, and further include low-cost press rollers 11 and 12. For this reason, the introduction cost of the roll press apparatus 1 which pressurizes the electrode member 90 can be reduced, and also the cost of a spare roller and the maintenance cost of the roll press apparatus 1 can be reduced.

DESCRIPTION OF SYMBOLS 1 apparatus (roll press apparatus) 11, 11 press roller 21 outer peripheral surface layer, 22 intermediate | middle layer, 23 axial layer 90 battery electrode member, 91 core material, 92 active material

Claims (3)

An apparatus for pressurizing an electrode member for a battery in which an active material is applied on a core material,
Having a pair of press rollers arranged to press across the electrode member;
Each of the pair of press rollers includes an outer peripheral surface layer and an intermediate layer inside the outer peripheral surface layer, the intermediate layer is made of resin, and the outer peripheral surface layer is harder than the intermediate layer. The layer is deformed at a portion sandwiching the electrode member, whereby a portion before and after the portion sandwiching the electrode member is also deformed.   2. The apparatus according to claim 1, wherein the outer peripheral surface layer and the intermediate layer of the pair of press rollers are made of resin, and the outer peripheral surface layer is obtained by blending an inorganic filler in the surface layer of the intermediate layer.   3. The apparatus according to claim 1, wherein each of the pair of press rollers includes a metal shaft layer located inside the intermediate layer.

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