JP2022177606A - Method of manufacturing electrode - Google Patents

Abstract

To provide a method of manufacturing an electrode capable of suppressing abrasion of a metal foil or rolls.SOLUTION: Provided is a method of manufacturing an electrode 70 that forms a first electrode layer 61 by pressing first wet powder P1 against a first surface S1 side of a metal foil 50 and forms a second electrode layer 62 by pressing second wet powder P2 against a second surface S2 side of the metal foil 50, using a first roll 11, a second roll 12, a third roll 13, and a fourth roll 14 that are made of a metal. The method includes: a first step Pr1 of forming a binding layer 63 on the second surface S2 of the metal foil 50; a second step Pr2 of forming the first electrode layer 61 on the first surface S1 of the metal foil 50 between the first roll 11 and the second roll 12; and a third step Pr3 of forming the second electrode layer 62 on the binding layer 63 between the third roll 13 and the fourth roll 14.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electrode manufacturing method.

In the coated article manufacturing apparatus described in Patent Document 1, the article to be coated passes between the first roll and the second roll rotating in the direction opposite to the rotation of the first roll. The object to be coated is conveyed in a direction corresponding to the rotation of the second roll. A mixture paint is supplied from a paint supply hopper between the first roll and the second roll. A coating film is manufactured by applying the mixture coating material to an object to be coated in the form of a coating film. Metal is adopted as the material of the first roll and the second roll. When manufacturing a negative electrode plate using the apparatus for manufacturing a coated product described in Patent Document 1, a negative electrode mixture coating containing a negative electrode active material, a binder, and a solvent is applied to a copper foil as an object to be coated. A negative electrode plate is manufactured by coating in the form of a film.

Patent Document 2 discloses a bipolar electrode in which a positive electrode active material layer and a negative electrode active material layer are formed on a metal foil. The negative electrode active material layer is formed on the first surface of the metal foil. The positive electrode active material layer is formed on the second surface of the metal foil.

JP 2015-164717 A JP 2012-234823 A

In recent years, it has been studied to form a bipolar electrode by a method similar to that of the above-described coating film manufacturing apparatus. However, when the object to be coated is a metal foil, the metal foil comes into contact with the roll when the mixture paint is first applied to the metal foil. Therefore, the metal foil or roll may be worn.

A method of manufacturing an electrode for solving the above-mentioned problems is to use a first roll, a second roll, a third roll, and a fourth roll to apply an electrode active material, a binder, and a solvent to a first surface side of a strip-shaped metal foil. Forming a first electrode layer by pressing a first wet powder containing A method of manufacturing an electrode for forming a second electrode layer, comprising a first step of forming a binding layer containing a binder and a conductive agent as main components on the second surface; With the layers in contact, the metal foil passes between the first roll and the second roll due to the rotation of the second roll, and the metal foil passes between the first roll and the second roll. a second step of forming the first electrode layer on one side; and after the second step, with the first electrode layer in contact with the third roll, the metal foil and the metal foil are rotated by rotating the third roll. A third roll in which the first electrode layer passes between the third roll and the fourth roll, and the second electrode layer is formed on the binding layer between the third roll and the fourth roll. and

According to this, when forming the first electrode layer on the metal foil in the second step, the binding layer formed in the first step comes into contact with the second roll. Therefore, the wear of the metal foil or the second roll can be suppressed. Similarly, when the second electrode layer is formed on the metal foil in the third step, the first electrode layer comes into contact with the third roll, so wear of the metal foil or the third roll can be suppressed. Therefore, wear of the metal foil or roll can be suppressed.

In the electrode manufacturing method described above, the electrode active material contained in the first wet powder may be a negative electrode active material, and the electrode active material contained in the second wet powder may be a positive electrode active material.
According to this, when the binder and solvent contained in the second wet powder are, for example, water-based, the second electrode layer becomes a water-based positive electrode active material layer. If the second electrode layer is a water-based positive electrode active material layer, it may be difficult to adhere the second electrode layer to the metal foil. In this respect, in the present embodiment, the electrode active material contained in the second wet powder is used as the positive electrode active material, and the second electrode layer is formed on the binding layer. Therefore, even if the second electrode layer is a water-based positive electrode active material layer, the second electrode layer can be brought into close contact with the metal foil via the binding layer.

In the electrode manufacturing method described above, the third step may be performed while the first electrode layer formed on the metal foil conveyed by the rotation of the second roll is in contact with the third roll.

According to this, since the second step and the third step can be performed on the metal foil that is continuously conveyed, the first electrode layer and the second electrode layer can be continuously formed on the metal foil. The electrode can be produced more efficiently than in the case where the metal foil after the second step is once wound up and then transported, and then the wound metal foil is transported again to carry out the third step.

In the electrode manufacturing method described above, the first roll, the second roll, the third roll, and the fourth roll are preferably made of metal.
According to this, since the 1st roll, the 2nd roll, the 3rd roll, and the 4th roll are made of metal which is hard compared with resin etc., it becomes easy to control wear of four rolls. Moreover, since the four rolls are made of metal, the rigidity of the four rolls can be ensured. Therefore, it is possible to suppress the deformation of the rolls when performing the second step and the third step. Therefore, variations in the thicknesses of the first electrode layer and the second electrode layer formed on the metal foil can be suppressed.

According to this invention, wear of the metal foil or roll can be suppressed.

The schematic of an electrode manufacturing apparatus. FIG. 4 is a cross-sectional perspective view when forming the binding layer on the second surface of the metal foil; FIG. 4 is a cross-sectional perspective view when forming the first electrode layer on the first surface of the metal foil; FIG. 4 is a cross-sectional perspective view when forming the second electrode layer on the second surface side of the metal foil; FIG. 2 is a cross-sectional view taken along line 5-5 in FIG. 1;

An embodiment embodying a method for manufacturing an electrode will be described below with reference to FIGS. 1 to 5. FIG. In describing the electrode manufacturing method, the configuration of the electrode manufacturing apparatus will also be described.
As shown in FIG. 1, the electrode manufacturing apparatus 1 forms the first electrode layer 61 by pressing the first wet powder P1 against the first surface S1 of the long strip-shaped metal foil 50, and This is an apparatus for forming the second electrode layer 62 by pressing the second wet powder P2 against the second surface S2. In the electrode manufacturing apparatus 1, the metal foil 50 is continuously conveyed. The electrode manufacturing apparatus 1 is an apparatus for continuously forming a first electrode layer 61 and a second electrode layer 62 on a continuously conveyed metal foil 50 .

<Electrode configuration>
As shown in FIG. 1, the electrode 70 comprises a metal foil 50, a first electrode layer 61, a second electrode layer 62 and a binding layer 63. As shown in FIG.

The metal foil 50 is formed by pasting together a long strip-shaped copper foil 51 and a long strip-shaped aluminum foil 52 . The metal foil 50 has a thickness of 1 mm or less. The width and length of the metal foil 50 are greater than its thickness. The first surface S<b>1 of the metal foil 50 is the surface opposite to the surface bonded to the aluminum foil 52 among both surfaces of the copper foil 51 in the thickness direction. The second surface S<b>2 of the metal foil 50 is the surface opposite to the surface bonded to the copper foil 51 among both surfaces of the aluminum foil 52 in the thickness direction. The metal foil 50 may be an aluminum foil 52 with one surface plated with copper. The metal foil 50 may be formed in one piece from one type of metal material. Note that the thicknesses of the metal foil 50, the first electrode layer 61, the second electrode layer 62, and the binding layer 63 shown in FIG. 1 are exaggerated.

The binding layer 63 is provided on the second surface S<b>2 of the metal foil 50 . A second electrode layer 62 is formed on the binding layer 63 . The binding layer 63 binds the second electrode layer 62 to the second surface S<b>2 of the metal foil 50 . The second electrode layer 62 is formed opposite to the metal foil 50 with the binding layer 63 as a reference. Therefore, it can be said that the second electrode layer 62 is formed on the second surface S2 side of the metal foil 50 . The binding layer 63 is mainly composed of a binding agent and a conductive aid. The binding layer 63 may contain a binding agent and a conductive aid as main components, and may contain other materials.

The binder is not particularly limited as long as it has a function of binding the metal foil 50 and the second electrode layer 62 . Examples of binders include rubber such as styrene-butadiene rubber, fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber, and thermoplastic resins such as polypropylene and polyethylene. Examples of binders include imide resins such as polyimide and polyamideimide, alkoxysilyl group-containing resins, and acrylic resins containing monomer units such as acrylic acid and methacrylic acid. A polymer having a hydrophilic group may be employed as the binder. Examples of hydrophilic groups of polymers having hydrophilic groups include carboxyl groups, sulfo groups, silanol groups, amino groups, hydroxyl groups, and phosphoric acid groups.

Specific examples of polymers having hydrophilic groups include polyacrylic acid and carboxymethylcellulose. Specific examples of polymers having hydrophilic groups include polymers containing carboxyl groups in the molecule such as polymethacrylic acid, and polymers containing sulfo groups such as poly(p-styrenesulfonic acid). Specific examples of polymers having hydrophilic groups include polyvinylpyrrolidone and polyvinyl alcohol. Polymers containing many carboxyl groups and/or sulfo groups, such as polyacrylic acid or copolymers of acrylic acid and vinylsulfonic acid, are water-soluble.

A polymer having a hydrophilic group is preferably a water-soluble polymer, and in terms of chemical structure, a polymer containing a plurality of carboxyl groups and/or sulfo groups in one molecule is preferable. In addition, as a binder, said various binders may be used individually, and 2 or more types may be used together.

The conductive aid may be any chemically inactive electron high conductor. Examples of conductive aids include carbon black, graphite, vapor-grown carbon fibers, carbon nanotubes, and various metal particles, which are carbonaceous fine particles. Examples of carbon black include acetylene black, Ketjenblack (registered trademark), furnace black, and channel black. These conductive aids can be added to the electrode material singly or in combination of two or more.

<Structure of First Wet Powder and Second Wet Powder>
The first wet powder P1 and the second wet powder P2 are materials with poor fluidity containing an electrode active material, a binder, and a solvent. The first wet powder P1 and the second wet powder P2 are materials in which the solid content is dispersed in a solvent in a range of 60% by mass to 90% by mass. The solid content is what remains after the solvent is separated from the first wet powder P1 and the second wet powder P2 by drying or the like. The solid content is the electrode material including electrode active material and binder.

The electrode active material contained in the first wet powder P1 is a negative electrode active material. Materials that can occlude and release charge carriers can be used as the negative electrode active material. The negative electrode active material is not particularly limited as long as it is a simple substance, an alloy, or a compound capable of intercalating and deintercalating charge carriers such as lithium ions. For example, as the negative electrode active material, group 14 elements such as lithium, carbon, silicon, germanium and tin, and group 13 elements such as aluminum and indium may be used singly. In addition, as the negative electrode active material, single elements of group 12 elements such as zinc and cadmium, group 15 elements such as antimony and bismuth, alkaline earth metals such as magnesium and calcium, and group 11 elements such as silver and gold are used. may Specific examples of alloys include tin-based materials such as Ag--Sn alloys, Cu--Sn alloys and Co--Sn alloys. Specific examples of the compound include carbon-based materials such as various types of graphite, and silicon-based materials such as SiOx (0.3≦x≦1.6) that disproportionates into simple silicon and silicon dioxide. Specific examples of the compound include a silicon simple substance or a composite obtained by combining a silicon-based material and a carbon-based material. Nb ₂ O ₅ , TiO ₂ , Li ₄ Ti ₅ O ₁₂ , WO ₂ , MoO ₂ , Fe ₂ O ₃ and other oxides, or Li ₃ -xMxN (M=Co, Ni, Cu) as the negative electrode active material. You may employ the nitride represented by. One or more of these materials can be used as the negative electrode active material.

The electrode active material contained in the second wet powder P2 is a positive electrode active material. As the positive electrode active material, a general formula of layered rock salt structure _{: LiaNibCocMndDeOf} (0.2≤a≤2, b ₊ c+d+e _{= 1} , 0≤e< ₁ , 1.7≤f≤ 3, D is W, Mo, Re, Pd, Ba, Cr, B, Sb, Sr, Pb, Ga, Al, Nb, Mg, Ta, Ti, La, Zr, Cu, Ca, Ir, Hf, Rh; at least one element selected from Fe, Ge, Zn, Ru, Sc, Sn, In, Y, Bi, S, Si, Na, K, P, V), Li ₂ MnO ₃ can be mentioned. Further, as the positive electrode active material, a spinel-structured metal oxide such as LiMn ₂ O ₄ , a solid solution composed of a mixture of a spinel-structured metal oxide and a layered compound, LiMPO ₄ , LiMVO ₄ or Li ₂ MSiO ₄ (formula in which M is selected from at least one of Co, Ni, Mn and Fe). Examples of the positive electrode active material include taborite compounds represented by LiMPO ₄ F (M is a transition metal) such as LiFePO ₄ F, and borate compounds represented by LiMBO ₃ (M is a transition metal) such as LiFeBO ₃ . . Any metal oxide used as a positive electrode active material may have the above compositional formula as a basic composition, and those in which the metal elements contained in the basic composition are replaced with other metal elements can also be used.

As the binder contained in the first wet powder P1 and the second wet powder P2, one or more of the binders exemplified as the binder contained in the binding layer 63 may be appropriately selected. The binder contained in the first wet powder P1 and the second wet powder P2 may be the same as the binder contained in the binding layer 63, or may be different. In this embodiment, the binder contained in the second wet powder P2 and the binder contained in the binding layer 63 are preferably dissolved in the same solvent.

The solvent for dispersing the solid content is not particularly limited, but water, N-methyl-2-pyrrolidone, alcohol and the like are employed. As will be described later, when the first wet powder P1 and the second wet powder P2 are pressed against the metal foil 50 by a roll press, the solvent includes N-methyl-2, which has excellent lubricity during compression on the pressure surface of the roll. -pyrrolidone is preferably included. In addition, a material classified as an electrode material can also be employed for part or all of the solvent. Moreover, the solvent may be one capable of dissolving part or all of the solid content.

<Structure of Electrode Manufacturing Apparatus>
As shown in FIG. 1, the electrode manufacturing apparatus 1 includes a first roll 11, a second roll 12, a third roll 13, and a fourth roll . The 1st roll 11, the 2nd roll 12, the 3rd roll 13, and the 4th roll 14 are metal. The diameters of the first roll 11, the second roll 12, the third roll 13, and the fourth roll 14 are all the same. The axes of the first roll 11, the second roll 12, the third roll 13, and the fourth roll 14 extend in the same direction so as to be parallel to each other. The roll surface of the first roll 11 and the roll surface of the fourth roll 14 are coated with a fluorine resin. The first roll 11, the second roll 12, the third roll 13, and the fourth roll 14 may be made of resin.

The second roll 12 is arranged at a predetermined first distance from the first roll 11 . The third roll 13 is arranged on the opposite side of the second roll 12 to the first roll 11 . The third roll 13 is arranged at a predetermined second distance from the second roll 12 . The fourth roll 14 is arranged on the opposite side of the third roll 13 to the second roll 12 . The fourth roll 14 is arranged at a predetermined third distance from the third roll 13 . The direction in which the axes of the four rolls 11, 12, 13, 14 extend is defined as the axial direction. The four rolls 11, 12, 13, and 14 are arranged at the same height in the direction of gravity A when the four rolls 11, 12, 13, and 14 are viewed from the outside in the axial direction. Although not shown, when the four rolls 11, 12, 13, and 14 are viewed from above in the direction of gravity A, the first ends of the four rolls 11, 12, 13, and 14 in the axial direction are aligned in the horizontal direction B. placed. Similarly, although not shown, when the four rolls 11, 12, 13, and 14 are viewed from above in the direction of gravity A, the second ends of the four rolls 11, 12, 13, and 14 in the axial direction are aligned in the horizontal direction B are arranged in a row. In addition, the second distance is sufficiently larger than the first distance and the third distance. The first distance is slightly smaller than the third distance.

The electrode manufacturing apparatus 1 includes a first guide roll 21 , a second guide roll 22 , a third guide roll 23 and a fourth guide roll 24 . The first guide roll 21, the second guide roll 22, the third guide roll 23, and the fourth guide roll 24 are cylindrical. The diameters of the first guide roll 21, the second guide roll 22, the third guide roll 23, and the fourth guide roll 24 are all the same. The axes of the first guide roll 21, the second guide roll 22, the third guide roll 23, and the fourth guide roll 24 extend in the same direction so as to be parallel to each other. The directions in which the axes of the four guide rolls 21, 22, 23, and 24 extend are the same as the directions in which the axes of the four rolls 11, 12, 13, and 14 extend.

The first guide roll 21 is arranged above the second roll 12 in the direction of gravity A when the first guide roll 21 is viewed from the outside in the axial direction. The first guide roll 21 is arranged closer to the second roll 12 than the third roll 13 in the horizontal direction B when the first guide roll 21 is viewed from the outside in the axial direction.

The second guide roll 22 is arranged below the second roll 12 in the direction of gravity A when the second guide roll 22 is viewed from the outside in the axial direction. When the second guide roll 22 is viewed from the outside in the axial direction, the second guide roll 22 is arranged closer to the second roll 12 than the first roll 11 in the horizontal direction B. The third guide roll 23 is arranged below the third roll 13 in the direction of gravity A when the third guide roll 23 is viewed from the outside in the axial direction. The third guide roll 23 is arranged closer to the third roll 13 than the second roll 12 in the horizontal direction B when the third guide roll 23 is viewed from the outside in the axial direction. The fourth guide roll 24 is arranged below the fourth roll 14 in the direction of gravity A when the fourth guide roll 24 is viewed from the outside in the axial direction. The fourth guide roll 24 is arranged closer to the fourth roll 14 than the third roll 13 in the horizontal direction B when the fourth guide roll 24 is viewed from the outside in the axial direction.

The electrode manufacturing apparatus 1 includes a first power section 31 , a second power section 32 and a control section 33 . The first power section 31 rotates the second roll 12 around the axis. The second power section 32 rotates the third roll 13 around the axis. The first power section 31 and the second power section 32 are, for example, electric motors. The control unit 33 includes a processor and a storage unit. As the processor, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or a DSP (Digital Signal Processor) is used. The storage unit includes RAM (Random Access Memory) and ROM (Read Only Memory). The memory stores program code or instructions configured to cause the processor to perform processes. Storage or computer-readable media includes any available media that can be accessed by a general purpose or special purpose computer. The control unit 33 may be configured by a hardware circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The control unit 33, which is a processing circuit, may include one or more processors operating according to a computer program, one or more hardware circuits such as ASIC and FPGA, or a combination thereof. The control unit 33 controls the rotation speed of the second roll 12 and the rotation speed of the third roll 13 by controlling the first power unit 31 and the second power unit 32 .

The first roll 11 and the second roll 12 are connected by a first power transmission mechanism (not shown). When the second roll 12 rotates, the first power transmission mechanism causes the first roll 11 to rotate in a direction opposite to the direction in which the second roll 12 rotates. The first power transmission mechanism is a gear mechanism with a predetermined gear ratio. The gear ratio of the first power transmission mechanism is set so that the speed at which the first roll 11 rotates is slightly slower than the speed at which the second roll 12 rotates. The third roll 13 and the fourth roll 14 are connected by a second power transmission mechanism (not shown). When the third roll 13 rotates, the second power transmission mechanism causes the fourth roll 14 to rotate in a direction opposite to the direction in which the third roll 13 rotates. The second power transmission mechanism is a gear mechanism with a predetermined gear ratio. The gear ratio of the second power transmission section is set so that the speed at which the fourth roll 14 rotates is slightly slower than the speed at which the third roll 13 rotates.

The metal foil 50 is wound around a supply roll (not shown). The supply roll is arranged above the first guide roll 21 . A winding roll (not shown) is arranged on the side of the fourth guide roll 24 . The metal foil 50 unwound from the supply roll passes through the electrode manufacturing apparatus 1 and is wound up on the winding roll. Specifically, the metal foil 50 unwound downward from the supply roll is conveyed in the horizontal direction B with its orientation changed by the first guide roll 21 so as to face the second roll 12 . The metal foil 50 whose direction has been changed by the first guide roll 21 is wound around the second roll 12 . After passing between the first roll 11 and the second roll 12 , the metal foil 50 is changed in direction by the second guide roll 22 toward the third guide roll 23 and conveyed in the horizontal direction B. The metal foil 50 is conveyed in the direction of gravity A after its direction is changed so that it faces upward in the direction of gravity A by the third guide roll 23 . The metal foil 50 whose direction has been changed by the third guide roll 23 is wound around the third roll 13 . After passing between the third roll 13 and the fourth roll 14, the metal foil 50 is changed in direction by the fourth guide roll 24 to be transported in the horizontal direction B toward the take-up roll. After that, the metal foil 50 is wound on a winding roll. Assuming that the direction in which the metal foil 50 is transported is the transport direction D, the power for transporting the metal foil 50 in the transport direction D is the torque of the second roll 12 and the torque of the third roll 13 . Further, the conveying direction D coincides with the longitudinal direction of the long band-shaped metal foil 50 .

The electrode manufacturing apparatus 1 includes a first wet-powder supply device 41 and a second wet-powder supply device 42 . The first wet powder supply device 41 is filled with the first wet powder P1. The first wet powder supply device 41 is arranged above the first roll 11 and the second roll 12 . The lower part of the first wet powder feeder 41 is inserted between the first roll 11 and the second roll 12 . The first wet powder supply device 41 is arranged closer to the first roll 11 than the second roll 12 is. The supply port 41 a of the first wet powder supply device 41 is provided closer to the first roll 11 than the second roll 12 between the first roll 11 and the second roll 12 .

The second wet powder supply device 42 is filled with the second wet powder P2. The second wet powder supply device 42 is arranged above the third roll 13 and the fourth roll 14 . The lower portion of the second wet powder feeder 42 is inserted between the third roll 13 and the fourth roll 14 . The second wet powder supply device 42 is arranged closer to the fourth roll 14 than the third roll 13 . The supply port 42 a of the second wet powder supply device 42 is provided closer to the fourth roll 14 than the third roll 13 between the third roll 13 and the fourth roll 14 .

The electrode manufacturing apparatus 1 has a drying device 80 . Examples of the drying device 80 include a hot air drying oven, an IR drying oven, a hot plate, and a heat roll. The drying device 80 is arranged below the second roll 12 .

A method of manufacturing the electrode 70 including the flow of the metal foil 50 from upstream to downstream in the conveying direction D and the molding order of the first electrode layer 61 and the second electrode layer 62 in the electrode manufacturing apparatus 1 will be described below. do.

<Method for manufacturing electrode>
The method for manufacturing the electrode 70 includes a first process Pr1, a second process Pr2, a third process Pr3, and a drying process Prd. The first step Pr<b>1 is a step of forming the binding layer 63 on the second surface S<b>2 of the metal foil 50 .

As shown in FIGS. 1 and 2, the first step Pr1 will be described in detail. In the first step Pr1, the binding layer 63 is formed by pressing a coating material containing a binding agent and a conductive aid as main components against the second surface S2 of the metal foil 50 . In the first step Pr1 of the present embodiment, the binding layer 63 is sufficiently dried by a drying device (not shown). A direction orthogonal to the longitudinal direction of the metal foil 50 and orthogonal to the thickness direction of the metal foil 50 is defined as a width direction C of the metal foil 50 . The width direction C is orthogonal to the transport direction D. In the first step Pr1, the application width W3 of the binding layer 63 in the width direction C is set narrower than the width W1 of the metal foil 50 in the width direction C. The binding layer 63 is pressed in the width direction C so as to form uncoated portions on both sides of the metal foil 50 in the width direction C where the binding layer 63 is not applied.

Next, the second step Pr2 will be explained. The second step Pr2 is performed after the first step Pr1. The second step Pr2 is a step of forming the first electrode layer 61 on the first surface S1 between the first roll 11 and the second roll 12 . In the second step Pr2, the metal foil 50 passes between the first roll 11 and the second roll 12 as the second roll 12 rotates while the binding layer 63 is in contact with the second roll 12 .

As shown in FIG. 1, the second step Pr2 will be described in detail. The first surface S<b>1 of the metal foil 50 passing through the electrode manufacturing apparatus 1 is in contact with the first guide roll 21 . As the second roll 12 rotates, the metal foil 50 and the binding layer 63 pass between the first roll 11 and the second roll 12 . The first surface S1 of the metal foil 50 and the first roll 11 are not in contact.

With the metal foil 50 passing between the first roll 11 and the second roll 12, the first wet powder P1 is continuously supplied from the supply port 41a of the first wet powder supply device 41. As shown in FIG. The first wet powder P1 is pressed against the first surface S1 of the metal foil 50 by the rotation of the first roll 11 . The first wet powder P1 is pressed in the thickness direction of the metal foil 50 by the first roll 11 and the second roll 12 . The first electrode layer 61 is formed on the first surface S1 of the metal foil 50 by pressing the first wet powder P1 against the first surface S1 of the metal foil 50 . Here, the first distance described above is set so that the first electrode layer 61 formed on the first surface S1 of the metal foil 50 has a predetermined thickness. The solvent contained in the first wet powder P1 has not been removed from the first electrode layer 61 immediately after passing between the first roll 11 and the second roll 12 . The first electrode layer 61 immediately after passing between the first roll 11 and the second roll 12 is a precursor of the negative electrode active material layer.

As shown in FIG. 3, in the second step Pr2, the application width W2 of the first wet powder P1 in the width direction C is set narrower than the width W1 of the metal foil 50 in the width direction C. As shown in FIG. The first wet powder P1 is pressed so as to form uncoated portions on both sides of the metal foil 50 in the width direction C where the first wet powder P1 is not pressed.

As shown in FIGS. 2, 3, and 5, the application width W2 of the first wet powder P1 in the second step Pr2 is set wider than the application width W3 of the binding layer 63 in the first step Pr1. there is In the thickness direction of the metal foil 50, the binding layer 63 is positioned within the range where the first electrode layer 61 is provided. In addition, in the thickness direction of the metal foil 50, the thickness of the binding layer 63 is sufficiently thinner than the thickness of the first electrode layer 61 and the thickness of the second electrode layer 62. It is set to the extent that it does not affect.

Next, the drying process Prd will be described. The drying process Prd is a process in which the first electrode layer 61 is dried by the drying device 80 . In the drying process Prd, drying of the first electrode layer 61 is performed while being transported between the second roll 12 and the third roll 13 .

As shown in FIG. 1 , the metal foil 50 immediately after forming the first electrode layer 61 is conveyed toward the drying device 80 while the binding layer 63 is in contact with the second guide roll 22 . The drying device 80 dries the first electrode layer 61 . The dried first electrode layer 61 is a negative electrode active material layer obtained by removing the solvent from the first wet powder P1.

Next, the third step Pr3 will be explained. The third step Pr3 is performed after the second step Pr2. The third step Pr3 is a step of forming the second electrode layer 62 on the second surface S2 side of the metal foil 50 between the third roll 13 and the fourth roll 14 . In the third step Pr3, while the first electrode layer 61 is in contact with the third roll 13, the rotation of the third roll 13 causes the metal foil 50 and the first electrode layer 61 to move between the third roll 13 and the fourth roll 14. pass through.

Specifically, the binding layer 63 formed on the metal foil 50 that has passed through the drying device 80 is in contact with the third guide roll 23 . As the third roll 13 rotates, the metal foil 50 having the first electrode layer 61 formed thereon passes between the third roll 13 and the fourth roll 14 . The binding layer 63 formed on the metal foil 50 and the fourth roll 14 are not in contact with each other.

With the first electrode layer 61 and the metal foil 50 passing between the third roll 13 and the fourth roll 14, the second wet powder P2 is continuously supplied from the supply port 42a of the second wet powder supply device 42. be done. The rotation of the fourth roll 14 presses the second wet powder P2 against the binding layer 63 . The second wet powder P2 is pressed in the thickness direction of the metal foil 50 by the third roll 13 and the fourth roll 14 . The second electrode layer 62 is formed on the second surface S2 side of the metal foil 50 by pressing the second wet powder P2 against the binding layer 63 . Here, the third distance described above is set so that the second electrode layer 62 formed on the second surface S2 side of the metal foil 50 has a predetermined thickness. The solvent contained in the second wet powder P2 is not removed from the second electrode layer 62 immediately after passing between the third roll 13 and the fourth roll 14 . The second electrode layer 62 immediately after passing between the third roll 13 and the fourth roll 14 is a precursor of the positive electrode active material layer.

As shown in FIG. 4 , in the third step Pr3, the application width W3 of the second wet powder P2 in the width direction C is the same as the application width W3 of the binding layer 63 .
As shown in FIGS. 4 and 5, in the thickness direction of the metal foil 50, the second electrode layer 62 is formed at the same position as the binding layer 63 is provided. In the thickness direction of the metal foil 50, the second electrode layer 62 is located within the range where the first electrode layer 61 is provided.

As shown in FIG. 1 , the metal foil 50 immediately after the second electrode layer 62 is formed is placed downstream in the conveying direction D while the second electrode layer 62 before drying is in contact with the fourth guide roll 24 . be transported. The second electrode layer 62 is appropriately dried by a drying device (not shown) arranged downstream of the fourth guide roll 24 in the transport direction D. As shown in FIG. The electrode 70 is completed when the drying of the second electrode layer 62 is completed. The electrode 70 manufactured by the electrode manufacturing apparatus 1 is a pseudo bipolar electrode in which the copper foil 51 and the aluminum foil 52 are regarded as one metal foil 50 . A first electrode layer 61 and a second electrode layer 62 are formed on the electrode 70 over the entire length in the conveying direction D of the metal foil 50 . The method for manufacturing the electrode 70 is a method for forming the first electrode layer 61 and the second electrode layer 62 on the strip-shaped metal foil 50 using four rolls 11, 12, 13, and 14, and includes a first step Pr1 , a second process Pr2, a third process Pr3, and a drying process Prd.

<Action of this embodiment>
The operation of this embodiment will be described.
When forming the first electrode layer 61 on the first surface S1 of the metal foil 50 in the second step Pr2, the binding layer 63 formed on the second surface S2 of the metal foil 50 in the first step Pr1 is applied to the second roll 12. Contact. Further, when forming the first electrode layer 61 on the metal foil 50 in the second step Pr2, the second surface S2 of the metal foil 50 and the first roll 11 do not come into contact with each other. Similarly, when the second electrode layer 62 is formed on the second surface S2 side of the metal foil 50 in the third step Pr3, the first electrode layer 61 formed on the first surface S1 of the metal foil 50 in the second step Pr2 is the second electrode layer 62. 3 contact the roll 13; Further, when forming the second electrode layer 62 on the second surface S2 side of the metal foil 50 in the third step Pr3, the binding layer 63 formed on the metal foil 50 and the fourth roll 14 do not come into contact with each other. That is, in manufacturing the electrode 70, the two surfaces S1, S2 of the metal foil 50 and the four rolls 11, 12, 13, 14 do not come into contact with each other.

<Effects of this embodiment>
Effects of the present embodiment will be described.
(1) Since the metal foil 50 does not contact the second roll 12 and the third roll 13 that convey the metal foil 50 having driving force, the second roll 12 and the metal foil 50, and the third roll 13 and the metal foil 50 It is possible to suppress wear with Furthermore, since both surfaces S1, S2 of the metal foil 50 and the four rolls 11, 12, 13, 14 do not come into contact with each other, abrasion of the metal foil 50 or the four rolls 11, 12, 13, 14 can be suppressed. In addition, contamination of the electrode 70 with abrasion powder can be reduced.

(2) When the binder and solvent contained in the second wet powder P2 are, for example, water-based, the second electrode layer 62 is a water-based positive electrode active material layer. If the second electrode layer 62 is a water-based positive electrode active material layer, it may be difficult for the second electrode layer 62 to adhere to the metal foil 50 . In this respect, in the present embodiment, the electrode active material contained in the second wet powder P2 is used as the positive electrode active material, and the second electrode layer 62 is formed on the binding layer 63 . Therefore, even if the second electrode layer 62 is a water-based positive electrode active material layer, the second electrode layer 62 can be brought into close contact with the metal foil 50 via the binding layer 63 .

(3) Since the second step Pr2 and the third step Pr3 can be performed on the metal foil 50 that is continuously conveyed, the first electrode layer 61 and the second electrode layer 62 are continuously formed on the metal foil 50. Moldable. Compared to the case where the metal foil 50 after the second step Pr2 is once wound up and the conveyance is stopped, the wound metal foil 50 is conveyed again and the third step Pr3 is performed, the electrode 70 can be efficiently removed. can be manufactured.

(4) Since the first roll 11, the second roll 12, the third roll 13, and the fourth roll 14 are made of metal that is harder than resin or the like, the four rolls 11, 12, 13, and 14 It becomes easy to suppress the wear of Moreover, since the four rolls 11, 12, 13, and 14 are made of metal, the rigidity of the four rolls 11, 12, 13, and 14 can be ensured. Therefore, deformation of the four rolls 11, 12, 13, and 14 when performing the second step Pr2 and the third step Pr3 can be suppressed. Therefore, variations in thickness of the first electrode layer 61 and the second electrode layer 62 formed on the metal foil 50 can be suppressed.

(5) The drying device 80 can remove the solvent of the first wet powder P1 forming the first electrode layer 61 . The first electrode layer 61 can be made difficult to stick to the third roll 13 in the third step Pr3.
(6) The roll surface of the first roll 11 and the roll surface of the fourth roll 14 are coated with fluorine resin. Therefore, when the first wet powder P1 is pressed against the first surface S1 of the metal foil 50 by the first roll 11, the first wet powder P1 can be easily released from the first roll 11. Further, when the second wet powder P2 is pressed against the binding layer 63 by the fourth roll 14, the second wet powder P2 can be easily released from the fourth roll 14.

<Change example>
In addition, this embodiment can be implemented with the following changes. This embodiment and the following modifications can be combined with each other within a technically consistent range.

(circle) 3rd process Pr3 was implemented in the state in which the 1st electrode layer 61 shape|molded by the metal foil 50 conveyed by rotation of the 2nd roll 12 contacted the 3rd roll 13, but it is not restricted to this. For example, after winding the metal foil 50 after the second step Pr2 once, the third step Pr3 may be performed using the wound metal foil 50 .

O The binding layer 63 may also be provided on the first surface S<b>1 of the metal foil 50 . In this case, the first electrode layer 61 is formed on the binding layer 63 formed on the first surface S<b>1 of the metal foil 50 . That is, the first electrode layer 61 is formed on the first surface S1 side of the metal foil 50 .

(circle) the electrode active material contained in the 1st wet powder P1 may be changed into a positive electrode active material, and the electrode active material contained in the 2nd wet powder P2 may be changed into a negative electrode active material. In this case, the surface of the aluminum foil 52 of the metal foil 50 located opposite to the copper foil 51 is defined as a first surface S1, and the surface of the copper foil 51 of the metal foil 50 located opposite to the aluminum foil 52 is defined as a second surface. S2. Also, the application width W3 of the second wet powder P2 is set wider than the application width W2 of the first wet powder P1. Similarly, the coating width in the width direction C of the binding layer 63 is set to be the same as the coating width W2.

(circle) the roll surface of the 1st roll 11 and the roll surface of the 4th roll 14 may implement surface treatments other than a fluororesin coat. It is sufficient if the first wet powder P1 can be easily released from the first roll 11 and the second wet powder P2 can be easily released from the fourth roll 14 . The fluororesin coating on the roll surface of the first roll 11 and the roll surface of the fourth roll 14 may be omitted, and the surface treatment may not be performed.

o Each diameter of the 1st roll 11, the 2nd roll 12, the 3rd roll 13, and the 4th roll 14 may differ.
(circle) the arrangement|positioning in the gravity direction A and the horizontal direction B of the 1st roll 11, the 2nd roll 12, the 3rd roll 13, and the 4th roll 14 may be changed suitably.

(circle) in the electrode manufacturing apparatus 1, the 2nd guide roll 22 and the 3rd guide roll 23 may be omitted. In this case, the metal foil 50 conveyed by the second roll 12 is changed to be directly conveyed to the third roll 13 . In addition, in the electrode manufacturing apparatus 1, the first guide roll 21 and the fourth guide roll 24 may also be omitted.

(circle) the 1st roll 11 and the 4th roll 14 may be changed into the roll which rotates independently. In this case, it is preferable to provide power units for rotating the first roll 11 and the fourth roll 14 and to control the power units by the control unit 33 .

(circle) you may provide the drying apparatus which dries the 2nd electrode layer 62 upstream rather than the 4th guide roll 24 in the conveyance direction D. FIG.
(circle) you may change so that the drying apparatus 80 may be provided in the downstream of the conveyance direction D rather than the 3rd roll 13 and the 4th roll 14. FIG. In this case, the drying device 80 may simultaneously dry the first electrode layer 61 and the second electrode layer 62 .

○ In the first step Pr1, the binding layer 63 was sufficiently dried by a drying device (not shown), but it does not have to be dried. The binding layer 63 may be dried in the drying device 80 together with the first electrode layer 61 . Also, similar to the above modification, the binding layer 63 may be dried together with the first electrode layer 61 and the second electrode layer 62 .

(circle) you may omit the drying apparatus 80. That is, the drying process Prd may be omitted from the manufacturing method of the electrode 70 . In such a change, the solvent contained in the first wet powder P1 preferably contains N-methyl-2-pyrrolidone.

DESCRIPTION OF SYMBOLS 1... Electrode manufacturing apparatus, 11... 1st roll, 12... 2nd roll, 13... 3rd roll, 14... 4th roll, 21... 1st guide roll, 22... 2nd guide roll, 23... 3rd guide roll , 24... Fourth guide roll, 31... First power unit, 32... Second power unit, 33... Control unit, 41... First wet powder supply device, 41a... Supply port, 42... Second wet powder supply Apparatus 42a Supply port 50 Metal foil 51 Copper foil 52 Aluminum foil 61 First electrode layer 62 Second electrode layer 63 Binding layer 70 Electrode 80 Drying device , S1... First surface, S2... Second surface, P1... First wet powder, P2... Second wet powder, W2... Application width of first wet powder, W3... Application width of second wet powder , A... Gravity direction, B... Horizontal direction, C... Width direction, D... Conveying direction, Pr1... First process, Pr2... Second process, Pr3... Third process, Prd... Drying process.

Claims (4)

By pressing the first wet powder containing the electrode active material, the binder, and the solvent against the first surface side of the strip-shaped metal foil using the first roll, the second roll, the third roll, and the fourth roll A method for manufacturing an electrode, comprising forming a first electrode layer and forming a second electrode layer by pressing a second wet powder containing an electrode active material, a binder, and a solvent against the second surface of the metal foil. and
a first step of forming a binding layer containing a binder and a conductive aid as main components on the second surface;
With the binding layer in contact with the second roll, the metal foil passes between the first roll and the second roll due to the rotation of the second roll. a second step of forming the first electrode layer on the first surface side between rolls;
With the first electrode layer in contact with the third roll after the second step, the metal foil and the first electrode layer are moved between the third roll and the fourth roll by rotating the third roll. and a third step of forming the second electrode layer on the binding layer between the third roll and the fourth roll. The electrode active material contained in the first wet powder is a negative electrode active material,
2. The method of manufacturing an electrode according to claim 1, wherein the electrode active material contained in the second wet powder is a positive electrode active material. The third step is carried out while the first electrode layer formed on the metal foil conveyed by the rotation of the second roll is in contact with the third roll. Item 3. A method for manufacturing the electrode according to item 2. The method for manufacturing an electrode according to any one of claims 1 to 3, wherein the first roll, the second roll, the third roll, and the fourth roll are made of metal. .

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