JP5510291B2 - Electrode plate manufacturing apparatus and battery manufacturing method - Google Patents

Description

  The present invention relates to an electrode plate manufacturing apparatus and a battery manufacturing method. More specifically, the present invention relates to an electrode plate manufacturing apparatus and a battery manufacturing method that can suitably apply a coating liquid to an electrode core material.

  Batteries are used in various fields such as electronic devices such as mobile phones and personal computers, vehicles such as hybrid vehicles and electric vehicles. Such a battery includes a positive electrode plate, a negative electrode plate, and an electrolyte. Further, in order to insulate the positive electrode plate and the negative electrode plate, it is common to provide a separator between them.

  For example, in a lithium ion secondary battery, as an electrode plate (positive electrode plate and negative electrode plate), a composite material layer (positive electrode composite material layer) containing an active material or the like in an electrode foil that is an electrode core material (positive electrode core material and negative electrode core material) And a negative electrode mixture layer) may be used. The manufacturing process of the electrode plate is as follows. First, a coating solution is prepared by kneading the active material and the binder. Next, a paste layer is formed on the electrode core material by applying the coating liquid to the electrode core material. Thereafter, the paste layer is dried while the electrode core material is conveyed into the drying furnace (drying step).

  In this drying process, convection of the coating liquid occurs inside the paste layer. For this reason, the binder present on the electrode core material side inside the paste layer may move to the vicinity of the surface of the paste layer (migration: see FIG. 2B of Patent Document 1). In this case, the binder is unevenly distributed on the surface of the composite layer in the composite layer of the electrode plate obtained after the coating liquid is dried. This means that there is a shortage of binder near the boundary with the electrode core inside the composite layer. In this way, the electrode plate on which migration has occurred easily peels off at the boundary where the binder is insufficient. That is, the peel strength is low.

  In the composite layer of the electrode plate having a low peel strength, peeling may occur in the subsequent manufacturing process. For example, when a battery having a wound electrode body obtained by winding an electrode plate and a separator is manufactured, the composite layer of the electrode plate may be peeled off in the winding process. This is because stress is applied to the electrode plate during winding.

  In addition, peeling may occur even after product shipment. In a lithium ion secondary battery, lithium ions are occluded (intercalated) or released (deintercalated) into the active material of the composite layer by charging and discharging. The volume of the composite layer changes due to the insertion and release of lithium ions. The amount of change in the volume of the composite layer is particularly large in the negative electrode plate. By such charging and discharging of the battery, the composite material layer repeatedly expands and contracts. Thereby, there exists a possibility that a composite material layer may peel locally.

  Almost no charge is transferred at the peeled portion in the composite layer. Therefore, the current collecting property at the peeling site is extremely low. That is, the battery performance of the lithium ion secondary battery using the electrode plate with the peeled portion is low. Therefore, it is preferable that the peeling strength of the composite layer in the electrode plate is high.

  Therefore, techniques for improving the peel strength of the electrode plate have been developed. For example, Patent Document 1 discloses a lithium ion secondary battery in which a negative electrode core material is formed with two coating layers. The manufacturing process of the lithium ion secondary battery in Patent Document 1 is approximately as follows. First, the first paste layer is applied to the negative electrode core material. Then, the first paste layer is dried to form a first coating layer (precoat layer). Subsequently, a second paste layer is applied on the dried first coating layer. Then, the second paste layer is dried to form a second coating layer (see paragraphs [0035] to [0037] of Patent Document 1). The first paste layer is a layer of a binder solution containing a binder. Thereby, it is supposed that a lithium ion secondary battery provided with the negative electrode plate from which a 2nd coating layer cannot peel easily from a negative electrode core material can be manufactured.

JP 2009-238720 A

  By the way, in patent document 1, the 1st coating layer (precoat layer) of an electrode plate does not contain an active material. Therefore, an electrode reaction does not occur inside the first coating layer. The place where the electrode reaction occurs is the second coating layer containing the active material. Therefore, the electrode core material collects current from the second coating layer. However, as described above, the first coating layer is formed between the electrode core material and the second coating layer. Therefore, the first coating layer becomes a factor that hinders charge transfer between the electrode core material and the second coating layer.

  Therefore, in the battery using the electrode plate in which the coating layer is formed between the electrode core material and the second coating layer as in Patent Document 1, the internal resistance is slightly high. Therefore, it is preferable to create an electrode plate having high peel strength without forming a separate coating layer between the second coating layer containing the active material and the electrode core material.

  The present invention has been made to solve the above-described problems of the prior art. That is, the place made into the subject is providing the manufacturing method of the electrode plate manufacturing apparatus and battery which can manufacture the electrode plate with high peeling strength in a coating layer.

  The electrode plate manufacturing apparatus according to one aspect of the present invention, which has been made for the purpose of solving this problem, applies a first coating liquid to an unwinding part for unwinding an electrode core material and one surface of the electrode core material. A first coating device for forming a first paste layer, and a second coating solution for applying a second coating liquid on the first paste layer of the electrode core material to form a second paste layer. Construction apparatus, drying furnace for drying the first paste layer and the second paste layer of the electrode core material while conveying the electrode core material, and an electrode core for drying the first paste layer and the second paste layer And a winding portion for winding the material. The first coating apparatus has a coating roller having a number of non-through holes formed on the surface by electrolytic etching. In such an electrode plate manufacturing apparatus, the first paste layer can be applied with a sufficiently thin coating thickness. Also, the second paste layer can be applied on the first paste layer before drying. And the peeling strength of the coating layer in the electrode plate manufactured with this electrode plate manufacturing apparatus is high. Furthermore, the electrode plate can be produced while being conveyed at a sufficiently high conveyance speed. Therefore, the productivity of the electrode plate is good.

In the electrode plate manufacturing apparatus described above, the average diameter of the non-through holes formed in the coating roller is 0.3 to 2.0 μm, and the average of the non-through holes formed in the coating roller is depth Ri 1~15μm der, the ratio occupied by the sum of the areas of the individual blind holes with respect to the total area of the region where the non-penetrating pores in the coating roller is formed 20 to 70%. This is because the paste layer can be applied with a coating thickness of about 0.7 to 2.0 μm even when transported at 10 m / min or more.

  In the electrode plate manufacturing apparatus described above, the first coating apparatus uses a gravure roll as a coating roller and rotates the gravure roll in a direction opposite to the direction in which the electrode core material is conveyed. Good. This is because the first paste layer can be suitably applied by the gravure coating apparatus.

  In the electrode plate manufacturing apparatus described above, the first coating apparatus may use a rod as a coating roller and rotate the rod in a direction that follows the conveying direction of the electrode core material. This is because the first paste layer can be suitably applied by the rod coating apparatus.

  In another embodiment of the present invention, a battery manufacturing method includes applying a coating liquid to an electrode core material to form a paste layer, and drying the paste layer while being transported in a drying furnace, so that a positive electrode plate or a negative electrode An electrode plate forming step for forming a plate, an electrode body forming step for forming a positive electrode plate and a negative electrode plate with a separator interposed therebetween, and arranging the electrode body inside the battery container and the inside of the battery container A battery assembly step of injecting an electrolyte into the battery and sealing it. In the electrode plate creation process, the first coating liquid is applied to the electrode core material to form the first paste layer, and the first paste layer of the electrode core material is formed on the electrode core material. A second coating step in which a second coating liquid is applied to form a second paste layer. And in a 1st coating process, it coats using the roller for coating by which many non-through-holes are formed in the surface by electrolytic etching. In such a battery manufacturing method, the first paste layer can be applied with a sufficiently thin coating thickness in the electrode plate forming step. Also, the second paste layer can be applied on the first paste layer before drying. And the peeling strength of the coating layer in the electrode plate manufactured through this electrode plate preparation process is high. Furthermore, the electrode plate can be produced while being conveyed at a sufficiently high conveyance speed. Therefore, the productivity of the electrode plate is good.

In the battery manufacturing method described above, the average diameter of the non-through holes formed in the coating roller is 0.3 to 2.0 μm, and the average of the non-through holes formed in the coating roller is depth Ri 1~15μm der, the ratio occupied by the sum of the areas of the individual blind holes with respect to the total area of the region where the non-penetrating pores in the coating roller is formed 20 to 70%. This is because the paste layer can be applied with a coating thickness of about 0.7 to 2.0 μm even when transported at 10 m / min or more.

  In the battery manufacturing method described above, in the first coating step, the coating roller may be rotated in the opposite direction to the direction in which the electrode core material is conveyed. This is because the first paste layer can be suitably applied by reverse kiss coating.

  In the battery manufacturing method described above, in the first coating step, the coating roller may be rotated in a direction that follows the conveying direction of the electrode core material. This is because the first paste layer can be suitably applied by kiss-type coating.

  ADVANTAGE OF THE INVENTION According to this invention, the electrode plate manufacturing apparatus which can manufacture an electrode plate with high peeling strength in a coating layer, and the manufacturing method of a battery are provided.

It is sectional drawing for demonstrating the structure of the battery manufactured by the manufacturing method of the battery which concerns on embodiment. It is a perspective view for demonstrating the winding electrode body of the battery manufactured by the manufacturing method of the battery which concerns on embodiment. It is an expanded view for demonstrating the winding structure of the winding electrode body in the battery manufactured by the manufacturing method of the battery which concerns on embodiment. It is a perspective sectional view showing the structure of the positive electrode plate (negative electrode plate) of the battery manufactured by the battery manufacturing method according to the embodiment. It is a perspective sectional view showing the structure of the positive electrode plate (negative electrode plate) manufactured by the electrode plate manufacturing apparatus according to the embodiment. It is a schematic block diagram for demonstrating the structure of the electrode plate manufacturing apparatus which concerns on 1st Embodiment. It is a conceptual diagram which shows a mode that the die coating apparatus of the electrode plate manufacturing apparatus which concerns on embodiment coats the coating liquid layer for negative electrodes on the binder solution layer. It is a perspective view for demonstrating the gravure roll of the electrode plate manufacturing apparatus which concerns on 1st Embodiment. It is a schematic block diagram for demonstrating the winding apparatus used with the manufacturing method of the battery which concerns on embodiment. It is a perspective view for demonstrating another gravure roll of the electrode plate manufacturing apparatus which concerns on 1st Embodiment. It is a schematic block diagram for demonstrating the structure of the electrode plate manufacturing apparatus which concerns on 2nd Embodiment.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail with reference to the accompanying drawings. In the present embodiment, the present invention is embodied in an electrode plate manufacturing apparatus and a battery manufacturing method for manufacturing an electrode plate of a lithium ion secondary battery.

(First embodiment)
1. Battery The battery according to the present embodiment is a cylindrical lithium ion secondary battery. FIG. 1 shows a cross-sectional view of the battery 10 of the present embodiment. As shown in FIG. 1, the battery 10 is a battery cell sealed by a battery case including a battery container 11 and a lid 12. The battery 10 includes a wound electrode body 100, a positive current collector 110, and a negative current collector 120. In addition, an electrolytic solution is injected into the battery container 11.

  The wound electrode body 100 repeats charging and discharging in the electrolytic solution and directly contributes to power generation. The positive electrode current collector plate 110 is a positive electrode current collector connected to a positive electrode core material of a wound electrode body 100 described later. The material is aluminum. The negative electrode current collector plate 120 is a negative electrode current collector connected to a negative electrode core material of a wound electrode body 100 described later. Its material is copper.

  A wound electrode body 100 of a lithium ion secondary battery according to this embodiment is shown in FIG. As shown in FIG. 2, the wound electrode body 100 is a laminated electrode body in which a positive electrode plate and a negative electrode plate are wound around an axis 101 and separators S and T are interposed therebetween. The shaft core 101 is a member that becomes the center when the wound electrode body 100 is wound. Its shape is cylindrical. The outer diameter of the shaft core 101 is about 3 to 20 mm. However, other outer diameters may be used. Examples of the material include polyphenylene sulfide (PPS). Of course, other materials may be used. In FIG. 2, a positive electrode non-coated portion P2 and a negative electrode non-coated portion N2 described later appear.

  The separators S and T are porous films such as polyethylene and polypropylene. The thicknesses of the separators S and T are about 10 to 50 μm. Here, the separator S and the separator T are made of the same material. For the understanding of the above winding order, only the codes are distinguished as S and T.

The electrolyte injected into the battery container 11 is obtained by dissolving an electrolyte in an organic solvent. Examples of organic solvents include ester solvents such as propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC), and ester solvents such as γ-butyrolactone (γ-BL), di- An organic solvent containing an ether solvent such as ethoxyethane (DEE) can be used. As the electrolyte salt, lithium salts such as lithium perchlorate (LiClO ₄ ), lithium borofluoride (LiBF ₄ ), and lithium hexafluorophosphate (LiPF ₆ ) can be used.

  FIG. 3 is a development view showing a wound structure of the wound electrode body 100. As shown in FIG. 3, the wound electrode body 100 is wound in a state where the positive electrode plate P, the separator S, the negative electrode plate N, and the separator T are stacked in this order from the inside.

The positive electrode plate P is obtained by applying a composite material containing a positive electrode active material capable of inserting and extracting lithium ions to an aluminum foil as a positive electrode core material. As the positive electrode active material, lithium composite oxides such as lithium nickelate (LiNiO ₂ ), lithium manganate (LiMnO ₂ ), and lithium cobaltate (LiCoO ₂ ) are used. The negative electrode plate N is obtained by applying a composite material containing a negative electrode active material capable of occluding and releasing lithium ions to a copper foil as a negative electrode core material. As the negative electrode active material, carbon-based materials such as amorphous carbon, non-graphitizable carbon, graphitizable carbon, and graphite are used.

  As shown in FIG. 3, the positive electrode plate P has a positive electrode coating portion P1 and a positive electrode non-coating portion P2. The positive electrode coating part P1 is a place where a positive electrode mixture layer containing a positive electrode active material or the like is formed on a positive electrode core material. The positive electrode non-coated portion P2 is a portion where the positive electrode mixture layer is not formed on the positive electrode core material. The negative electrode plate N includes a negative electrode coating portion N1 and a negative electrode non-coating portion N2. The negative electrode coating portion N1 is a portion where a negative electrode mixture layer containing a negative electrode active material or the like is formed on a negative electrode core material. The negative electrode non-coated portion N2 is a portion where the negative electrode mixture layer is not formed on the negative electrode core material.

  An arrow A in FIG. 3 indicates the width direction (vertical direction in FIG. 2) of the positive electrode plate P, the negative electrode plate N, and the separators S and T. An arrow B in FIG. 3 indicates the longitudinal direction of the positive electrode plate P, the negative electrode plate N, and the separators S and T (the circumferential direction of the wound electrode body 100 in FIG. 2).

2. Electrode Plate FIG. 4 is a perspective sectional view of the positive electrode plate P (or the negative electrode plate N). In FIG. 4, each symbol outside the parentheses indicates each part in the case of the positive electrode, and each symbol in the parenthesis indicates each part in the case of the negative electrode. The direction indicated by arrow A in FIG. 4 is the same as the direction indicated by arrow A in FIG. That is, it is the width direction of the positive electrode plate P. The direction indicated by arrow B in FIG. 4 is the same as the direction indicated by arrow B in FIG. That is, it is the longitudinal direction of the positive electrode plate P.

  As shown in FIG. 4, the positive electrode plate P is obtained by forming a positive electrode mixture layer PA on a part of both surfaces of a strip-like positive electrode core material PB. On the left side in FIG. 4, a positive electrode non-coated portion P2 of the positive electrode plate P protrudes in the width direction. The positive electrode non-coated portion P2 is formed in a strip shape. The positive electrode uncoated portion P2 is a region where the positive electrode mixture is not applied to both surfaces of the positive electrode core material PB. Therefore, in the positive electrode non-coating portion P2, the positive electrode core material PB is still exposed. On the other hand, on the right side in FIG. 4, there is no protrusion corresponding to the positive electrode non-coated portion P2. In the positive electrode coating part P1, the positive electrode mixture layer PA is formed with a uniform thickness on both surfaces of the positive electrode core material PB.

The positive electrode mixture layer PA is a layer formed by applying a mixture containing a positive electrode active material capable of occluding and releasing lithium ions to an aluminum foil that is the positive electrode core material PB. As the positive electrode active material, lithium composite oxides such as lithium nickelate (LiNiO ₂ ), lithium manganate (LiMnO ₂ ), and lithium cobaltate (LiCoO ₂ ) are used. In addition, the composite material includes a binder such as polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), and polyvinylidene fluoride (PVDF), and a thickener such as carboxymethyl cellulose (CMC).

  As shown in FIG. 4, the negative electrode plate N is obtained by forming a negative electrode mixture layer NA on a part of both surfaces of a strip-shaped negative electrode core material NB. On the left side in FIG. 4, the negative electrode non-coated portion N2 of the negative electrode plate N protrudes in the width direction. The negative electrode non-coated portion N2 is formed in a strip shape. The negative electrode non-coated portion N2 is a region where the negative electrode mixture is not applied to both surfaces of the negative electrode core material NB. Therefore, in the negative electrode non-coating portion N2, the negative electrode core material NB is still exposed. On the other hand, on the right side in FIG. 4, there is no protrusion corresponding to the negative electrode non-coated portion N2. In the negative electrode coating portion N1, the negative electrode mixture layer NA is formed with a uniform thickness on both surfaces of the negative electrode core material NB.

  The negative electrode mixture layer NA is a layer formed by applying a mixture containing a negative electrode active material capable of occluding and releasing lithium ions to a copper foil as the negative electrode core material NB. As the negative electrode active material, carbon-based materials such as amorphous carbon, non-graphitizable carbon, graphitizable carbon, and graphite are used. The composite material contains a binder such as polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), and polyvinylidene fluoride (PVDF), and a thickener such as carboxymethyl cellulose (CMC).

3. Electrode plate manufacturing apparatus The electrode plate manufacturing apparatus of this embodiment will be described. The electrode plate manufacturing apparatus of this embodiment is for manufacturing the positive electrode plate PX and the negative electrode plate NX shown in FIG. The positive electrode plate PX and the negative electrode plate N shown in FIG. 4 can be produced by slitting the positive electrode plate PX and the negative electrode plate NX shown in FIG. 5 along the line L in FIG.

  That is, the electrode plate manufacturing apparatus of this embodiment forms an electrode mixture layer (positive electrode mixture layer PA and negative electrode mixture layer NA) on an electrode core material (positive electrode core material PB and negative electrode core material NB). Plates (positive electrode plate PX and negative electrode plate NX) are prepared. Each part of the electrode plate manufacturing apparatus according to the present embodiment plays the same role in both the production process of the positive electrode plate PX and the production process of the negative electrode plate NX. Therefore, the configuration of the electrode plate manufacturing apparatus will be described by taking as an example the case of manufacturing the negative electrode plate NX on behalf of these.

  A schematic configuration of the electrode plate manufacturing apparatus 1000 of this embodiment is shown in FIG. The electrode plate manufacturing apparatus 1000 includes an unwinding unit 1100, a coating unit 1200, a drying furnace 1300, and a winding unit 1400.

3-1. Unwinding part The unwinding part 1100 has an unwinding reel 1101. The unwinding reel 1101 is for unwinding uncoated foil, that is, the negative electrode core material NB.

3-2. Coating Unit The coating unit 1200 includes a gravure coating device 1210 and a die coating device 1250 as shown in FIG. The gravure coating device 1210 is disposed at a position upstream from the die coating device 1250 in the conveyance direction of the negative electrode core material NB. The gravure coating device 1210 is a first coating device for applying a binder solution to the negative electrode core material NB. The die coating apparatus 1250 is a second coating apparatus for applying a negative electrode coating liquid onto a paste layer made of a binder solution of the negative electrode core material NB.

  The gravure coating apparatus 1210 includes a gravure roll 1211, a liquid tank 1212, a doctor blade 1213, and guide rollers 1214 and 1215. The gravure roll 1211 is a coating roller for coating the negative electrode core material NB with the binder solution layer NA1 (see FIG. 7). A large number of non-through holes are formed on the surface of the gravure roll 1211 as described later. The liquid tank 1212 is for containing a binder solution. The gravure roll 1211 is immersed in the binder solution in the liquid tank 1212. Therefore, the binder solution can enter the non-through holes of the gravure roll 1211.

  The doctor blade 1213 is for removing a part of the binder solution from the gravure roll 1211 before coating. This is to prevent the binder solution layer NA1 applied to the negative electrode core material NB from becoming too thick. The guide rollers 1214 and 1215 are rollers for increasing the contact area between the negative electrode core material NB and the gravure roll 1211.

  The negative electrode core material NB is conveyed in the direction of arrow C in FIG. When coating, the gravure roll 1211 rotates in the direction of arrow D in FIG. That is, the gravure roll 1211 rotates in the direction opposite to the direction following the conveyance direction of the negative electrode core material NB. Thus, the gravure coating apparatus 1210 is a reverse kiss type coating apparatus.

  The die coating apparatus 1250 has a coating die 1251 and a backup roller 1252. As shown in FIG. 7, the coating die 1251 is for coating the negative electrode coating liquid layer NA2 on the binder solution layer NA1 coated on the negative electrode core material NB. The backup roller 1252 is for conveying the negative electrode core material NB and supporting the negative electrode core material NB during coating by the coating die 1251.

3-3. Drying furnace The drying furnace 1300 transports the negative electrode core material NB coated with the binder solution layer NA1 and the negative electrode coating liquid layer NA2 to the inside thereof, and the binder solution layer NA1 and the negative electrode coating material NA1. This is for drying the working fluid layer NA2. The drying furnace 1300 includes an air nozzle 1301 and a roller 1302, as shown in FIG. The air nozzle 1301 is a nozzle for blowing hot air onto the undried negative electrode coating liquid layer NA2. The undried binder solution layer NA1 and the negative electrode coating solution layer NA2 are dried by hot air blown from the air nozzle 1301. The roller 1302 is a free roller for conveying the negative electrode core material NB.

3-4. Winding unit The winding unit 1400 has a winding reel 1401. The take-up reel 1401 is for taking up the negative electrode core material NB on which the negative electrode mixture layer NA is formed. As will be described later, the binder solution layer NA1 and the negative electrode coating solution layer NA2 become a single negative electrode mixture layer NA after drying.

4). Gravure roll 4-1. Non-Through Hole of Gravure Roll Here, the gravure roll 1211 of this embodiment will be described. Of course, the gravure roll 1211 has a cylindrical shape. The outer diameter of the cylinder is about 40 to 50 mm. The gravure roll 1211 is a solid roller. Alternatively, a hollow roller may be used. The gravure roll 1211 is made of aluminum.

  As shown in FIG. 8, a large number of non-through holes 1211 a are formed on the surface of the gravure roll 1211. These non-through holes 1211 a are formed over the entire surface of the gravure roll 1211. The average diameter of the non-through holes 1211a is 0.3 to 2.0 μm. The average depth of the non-through holes 1211a is 1 to 15 μm.

  The area of the gravure roll 1211 where the non-through hole 1211a is formed is defined as a non-through hole area V. In this embodiment, the non-through-hole region area V is the total surface area of the gravure roll 1211. The sum total of the areas of the individual non-through holes 1211a in the non-through hole region area V of the gravure roll 1211 is defined as a non-through hole area sum W. At this time, the non-through-hole area sum W with respect to the non-through-hole area | region area V is in the range of 20 to 70%.

4-2. Formation Method of Non-Through Holes in Gravure Roll In order to form a large number of non-through holes 1211a in the gravure roll 1211, electrolytic etching is used. What is necessary is just to use what is normally used when electrolytically etching aluminum, such as hydrochloric acid, as electrolyte solution in that case. As a condition at that time, the value of the anodizing ratio is preferably 1.3 nm / V. This is because it can be processed with high accuracy. By this electrolytic etching, a gravure roll 1211 having a large number of non-through holes 1211a can be manufactured.

  Thus, in the electrode plate manufacturing apparatus 1000 of this embodiment, the gravure roll 1211 in which many fine non-through holes 1211a are formed is used as the first coating apparatus. Therefore, the thickness of the paste layer of the binder solution can be applied with a thickness of about 0.7 to 2.0 μm. At that time, the electrode core material can be conveyed at a speed of 10 m / min or more as will be described later. Even if the electrode core material is applied in this speed region, the paste layer can be uniformly applied with a thin thickness of 0.7 to 2.0 μm. This thickness is the thickness of the liquid layer (slurry) at the time of coating, not the thickness of the solid layer after drying.

5. Electrode plate production process using electrode plate production apparatus The production process of the positive electrode plate P and the production process of the negative electrode plate N are substantially the same. The only difference is the raw materials such as the core material and coating liquid. Therefore, the production process of the negative electrode plate N will be described on behalf of these.

5-1. Coating process 5-1-1. First Coating Step First, the negative electrode plate NX is created using the electrode plate manufacturing apparatus 1000 shown in FIG. The negative electrode core material NB is unwound from the unwinding reel 1101 of the unwinding portion 1100. Here, the conveyance speed is 10 m / min or more. This conveyance speed is a constant value from the time when the negative electrode core material NB is unwound in the electrode plate manufacturing apparatus 1000 until it is wound after coating and drying.

  Next, the negative electrode core material NB is conveyed to the location of the gravure coating apparatus 1210 in the direction of arrow C in FIG. Then, the binder solution (first coating solution) is applied to the first surface of the negative electrode core material NB by the gravure roll 1211. Thereby, the binder solution layer NA1 is formed on the first surface of the negative electrode core material NB. The binder solution layer NA1 is a first paste layer. The thickness of the binder solution layer NA1 is about 0.7 to 2.0 μm.

5-1-2. Second Coating Step Subsequently, the negative electrode core material NB coated with the binder solution layer NA1 is conveyed to a location of the die coating device 1250. As shown in FIG. 7, the die coating apparatus 1250 applies the negative electrode coating liquid (second coating liquid) to the first surface of the negative electrode core material NB. At this time, the binder solution layer NA1 is of course not dry. For this reason, the negative electrode coating liquid layer NA2 is formed on the binder solution layer NA1 of the negative electrode core material NB. The negative electrode coating liquid layer NA2 is a second paste layer. The thickness of the negative electrode coating liquid layer NA2 is 10 to 100 μm.

  In addition, although mentioned later for details, the density | concentration of the binder in a binder solution is higher than the density | concentration of the binder in the coating liquid for negative electrodes. Therefore, immediately after coating by the die coating apparatus 1250, the concentration of the binder in the binder solution layer NA1 is higher than the concentration of the binder in the negative electrode coating solution layer NA2. In FIG. 7, the thickness of the binder solution layer NA1 and the thickness of the negative electrode coating solution layer NA2 are illustrated as being approximately the same. However, actually, the thickness of the binder solution layer NA1 is sufficiently thinner than the thickness of the negative electrode coating solution layer NA2.

  After this coating, at least a part of the binder solution layer NA1 and the negative electrode coating solution layer NA2 are mixed with each other. Hereinafter, a mixture of at least a part of the binder solution layer NA1 and the negative electrode coating solution layer NA2 will be referred to as paste layers NA1 and NA2. The concentration of the binder on the negative electrode core material NB side in the paste layers NA1 and NA2 is still higher than the concentration of the binder on the surface side in the paste layers NA1 and NA2.

5-2. Drying Step Subsequently, the coated negative electrode core material NB is conveyed into the drying furnace 1300 in the direction of arrow E in FIG. These paste layers NA1 and NA2 are dried by hot air blown from the air nozzle 1301. Due to the temperature rise due to this drying, convection occurs inside the film thickness of the paste layers NA1 and NA2. Therefore, the mixing of the solution in the paste layers NA1 and NA2 is further promoted.

  That is, the mixing of the solutions in the paste layers NA1 and NA2 and the volatilization of the solvent in the paste layers NA1 and NA2, that is, the drying occur simultaneously. Therefore, as the drying continues, the paste layers NA1 and NA2 become almost a single liquid layer. Therefore, the negative electrode mixture layer NA is formed on the negative electrode core material NB after drying.

  The negative electrode core material NB having the negative electrode mixture layer NA formed on the first surface in this manner is taken up by the take-up reel 1501 of the take-up unit 1500.

  Next, the negative electrode mixture layer NA is formed on the second surface of the negative electrode core material NB having the negative electrode mixture layer NA formed on the first surface. For this step, the electrode plate manufacturing apparatus 1000 may be used again. Thereby, the negative electrode plate NX shown in FIG. 5 can be produced. Further, the positive electrode plate PX can be similarly produced.

  In the negative electrode plate NX produced as described above, the concentration of the binder on the negative electrode core layer NB side in the negative electrode mixture layer NA is higher than the concentration of the binder on the surface side in the negative electrode mixture layer NA. Slightly expensive. Therefore, the peel strength of the negative electrode mixture layer NA in the negative electrode plate N of this embodiment is high. That is, the negative electrode mixture layer NA is difficult to peel off. Of course, the same applies to the positive electrode plate PX.

6). Battery Manufacturing Method Next, a battery manufacturing method of this embodiment will be described. As described above, the battery manufacturing method according to this embodiment is characterized in that the electrode plate manufacturing apparatus 1000 is used for manufacturing the positive electrode plate PX and the negative electrode plate NX. That is, there is a feature in an electrode plate creation process in which a coating liquid is applied to the electrode core material (positive electrode core material PB and negative electrode core material NB) to create electrode plates (positive electrode plate PX, negative electrode plate NX).

6-1. Coating liquid preparation process 6-1-1. First, a kneading process for preparing a positive electrode coating liquid for forming the positive electrode mixture layer PA will be described. The positive electrode active material, conductive material, thickening material, and solvent used here may be used. Then, the positive electrode active material, the conductive material, and the thickening material are mixed in the solvent in the kneading machine and stirred with the kneading blade. Thereby, the coating liquid for positive electrodes is created.

6-1-2. Negative electrode coating liquid kneading step A kneading step for preparing a negative electrode coating solution for forming the negative electrode mixture layer NA will be described. The negative electrode active material, thickening material, and solvent used here may be used. Then, in the kneader, the negative electrode active material and the thickening material are mixed in the solvent and stirred with the kneading blade. Thereby, the coating liquid for negative electrodes is created.

6-1-3. Binder solution preparation process In addition, a binder solution is prepared. The binder solution is a solution obtained by mixing a binder and a solvent. In addition, a common binder solution is prepared for the positive electrode and the negative electrode. The solvent is the same as that used for the positive electrode coating solution and the negative electrode coating solution. Further, the same binder as that used in the positive electrode coating solution and the negative electrode coating solution may be used. This is because after the positive electrode coating solution or the negative electrode coating solution is applied onto the binder solution, the positive electrode coating solution or the negative electrode coating solution and the binder solution are mixed well.

  Here, the concentration of the binder in the binder solution is, of course, larger than the concentration of the binder in the positive electrode coating solution and the concentration of the binder in the negative electrode coating solution.

  The order of creating these coating liquids described above does not matter. That is, you may create in any order. Further, when the solvent used for the positive electrode coating solution and the negative electrode coating solution are different, two types of binder solutions for the positive electrode and the negative electrode may be prepared.

6-2. Electrode plate preparation process As mentioned above, the negative electrode plate NX is produced using the electrode plate manufacturing apparatus 1000 of this embodiment. Subsequently, the negative electrode plate NX is cut along the line L in FIG. Thereby, the negative electrode plate N shown in FIG. 4 can be produced. Further, the positive electrode plate P can be similarly prepared.

6-3. Electrode body preparation process Subsequently, it winds, laminating | stacking the separators S and T on the positive electrode plate P and the negative electrode plate N using the winding apparatus 3000 shown in FIG. The winding device 3000 includes a positive electrode plate supply unit 3001, a negative electrode plate supply unit 3002, separator supply units 3003 and 3004, and a winding shaft 3005. Here, as shown in FIG. 3, the positive electrode plate P, the separator S, the negative electrode plate N, and the separator T are stacked and wound in order from the inside. The wound electrode body 100 is created by rotating the wound shaft 3005 in the direction of arrow F in FIG.

6-4. Battery Assembly Process Subsequently, the wound electrode body 100 is disposed inside the battery container 11. Then, an electrolytic solution is injected into the battery container 11. The lid 12 is then sealed. Alternatively, the liquid inlet may be sealed after the lid 12 is attached to the battery container 11. Thereby, the battery 10 of this embodiment is assembled. After this, it is advisable to perform processing such as conditioning and aging and various inspection processes. The battery 10 of this embodiment is manufactured through the above steps.

7). Modification 7-1. Double structure of gravure roll The gravure roll 1211 of this embodiment is a solid roller or a hollow roller. However, as shown in FIG. 10, a gravure roll 1230 having a double structure may be used. The gravure roll 1230 has an outer peripheral part 1231 and an inner shaft part 1232.

  The outer peripheral portion 1231 has a cylindrical shape that covers the inner shaft portion 1232 from the outside. A large number of non-through holes 1231 a are formed on the surface of the outer peripheral portion 1231. The average diameter, average depth, and the like of these non-through holes 1231a may be the same as those of the non-through holes 1211a of the gravure roll 1211. The material of the outer peripheral part 1231 is aluminum, for example. This is an example, and other materials may be used. The inner shaft portion 1232 has a cylindrical shape. The material of the inner shaft portion 1232 is, for example, stainless steel (SUS). The material of the inner shaft portion 1232 may be other material as long as it is stronger than the metal of the outer peripheral portion 1231. Therefore, the strength of the gravure roll 1230 is higher than the strength of the gravure roll 1211.

7-2. In this embodiment, the entire surface of the gravure roll 1211 is subjected to electrolytic etching. That is, the gravure roll 1211 was immersed in the electrolytic solution as it was. However, only a part of the gravure roll may be immersed in the electrolytic solution. However, it is necessary to perform electrolytic etching at least in the region used for coating. This is for forming the non-through hole 1231a.

7-3. When the binder solution is applied only to the negative electrode plate In this embodiment, the binder solution is applied not only to the negative electrode plate N but also to the positive electrode plate P. However, only when the negative electrode plate N is prepared, the binder solution may be applied. That is, when producing the positive electrode plate P, it is good also as applying only the coating liquid for positive electrodes, without applying a binder solution to the positive electrode core material PB.

  This is due to the following reason. In the positive electrode mixture layer PA or the negative electrode mixture layer NA, intercalation in which lithium ions enter the molecular structure of the positive electrode active material or the negative electrode active material occurs due to charge / discharge. The volume change of the negative electrode mixture layer NA due to this intercalation is larger than the volume change of the positive electrode mixture layer PA. Therefore, the negative electrode mixture layer NA is more easily peeled off than the positive electrode mixture layer PA. Therefore, when producing the positive electrode plate P, the binder solution may not be applied. In this case, it is necessary to mix a binder into the positive electrode coating solution.

7-4. Double-sided coating type electrode plate manufacturing apparatus The electrode plate manufacturing apparatus 1000 of this embodiment is of the single-sided coating type as shown in FIG. However, the present invention can naturally be applied to a double-sided coating type electrode plate manufacturing apparatus. In that case, if a gravure coating device 1210 and a die coating device 1250 for coating the second surface of the electrode core material are arranged in this order at a position downstream from the drying furnace 1300 in the transport direction of the electrode core material. Good. Further, it is necessary to provide a drying furnace for drying the second surface further downstream.

7-5. Direction of Die Coating Device In this embodiment, as shown in FIG. 6, the coating die 1251 is disposed sideways on the side of the backup roller 1252. However, the coating die 1251 may be arranged so that coating is performed from the lower side of the backup roller. This is because the coating liquid can be applied to the electrode core material.

7-6. Gravure coating apparatus In this embodiment, a gravure coating apparatus 1210 applies a binder solution to an electrode core material, and a die coating apparatus 1250 applies a positive electrode coating liquid or a negative electrode coating liquid to the electrode core material. I decided to work. However, two gravure coating apparatuses may be provided. In that case, the gravure coating device disposed downstream will apply the positive electrode coating solution or the negative electrode coating solution.

7-7. Transport Method in Drying Furnace In this embodiment, as shown in FIG. 6, a roller 1302 is used for transporting the electrode core material in the drying furnace 1300. However, the conveyance of the electrode core material inside the drying furnace 1300 may be performed not by roller conveyance using the roller 1302 but by an air floating method.

7-8. Heating method In this embodiment, the paste layers NA1 and NA2 are dried by blowing hot air from the air nozzle 1301 toward the paste layers NA1 and NA2 of the negative electrode core material NB. However, any other heating method may be used as long as it is a heating method for drying the paste layers NA1 and NA2. For example, infrared heating (IR) or induction heating (IH) can be used.

7-9. Number of connected drying furnaces The drying furnace 1300 of this embodiment is a single-stage drying furnace. However, the number of ovens in this drying oven can be changed arbitrarily. The paste layers NA1 and NA2 can be dried with a preferable drying profile when the number of furnaces is increased. However, the cost of the electrode plate manufacturing equipment increases as the number of furnaces increases.

8). Summary As described above in detail, the electrode plate manufacturing apparatus 1000 according to the present embodiment includes the gravure coating apparatus 1210 and the die coating apparatus 1250. The electrode plate manufacturing apparatus 1000 has a gravure roll 1211 in which fine non-through holes 1211a are formed. Since the non-through hole 1211a is fine, a paste layer of a binder solution having a thin coating thickness can be applied. Thereby, the electrode plate manufacturing apparatus 1000 which can produce the positive electrode plate PX and the negative electrode plate NX provided with sufficient peel strength is realized.

  Moreover, the manufacturing method of the battery of this embodiment is a method having an electrode plate creation step. In the electrode plate forming step, the binder solution is thinly applied to the electrode core material using the gravure roll 1211 in which a large number of non-through holes 1211a are formed by electrolytic etching, and the coating solution is applied thereon by a die coating apparatus. Apply and dry. Therefore, the positive electrode plate P and the negative electrode plate N having sufficient peel strength between the electrode core material and the coating layer can be manufactured. Therefore, in the battery manufacturing method of the present embodiment, a battery with high peel strength of the coating layer on the positive electrode plate P and the negative electrode plate N can be manufactured.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, the gravure roll material is not limited to aluminum. Other materials may be used as long as the material can form many non-through holes by electrolytic etching.

  It can also be applied to batteries that do not have an axial core. Moreover, it is not restricted to a cylindrical battery. A battery using a wound electrode body can be similarly applied. For example, the present invention can be applied to a battery cell that does not have an axial core inside the battery cell. Further, the present invention can also be applied to a rectangular battery having a flat wound electrode body that is produced by flat pressing the wound electrode body. Further, the present invention can also be applied to a battery using an electrode body in which a positive electrode plate and a negative electrode plate are stacked without winding. Moreover, it is not restricted to a lithium ion secondary battery. The present invention can also be applied to nickel metal hydride batteries and other secondary batteries. Moreover, if it is a battery, it can apply not only to a secondary battery but to a primary battery.

(Second Embodiment)
A second embodiment will be described. The configuration of the electrode plate manufacturing apparatus according to this embodiment is substantially the same as the configuration of the electrode plate manufacturing apparatus described in the first embodiment. The difference is that a rod coating device is provided instead of the gravure coating device. Therefore, the differences will be mainly described. Further, similarly to the first embodiment, a case where the negative electrode plate PX is manufactured will be described as an example.

1. Electrode plate manufacturing apparatus The schematic structure of the electrode plate manufacturing apparatus 2000 of this form is shown in FIG. The electrode plate manufacturing apparatus 2000 has substantially the same configuration as the electrode plate manufacturing apparatus 1000 (see FIG. 6) according to the first embodiment as described above. The difference is the coating part 2200. The coating unit 2200 includes a rod coating apparatus 2210 and a die coating apparatus 1250 as shown in FIG.

  The rod coating device 2210 is a first coating device having a rod 2211 and a support member 2212. The rod 2211 is a coating roller for coating the negative electrode core material NB with the binder solution layer NA1. The support member 2212 supports the rod 2211 and is also a tank for supplying the coating liquid to the rod 2211. The rod coating device 2210 is a kiss-type coating device. That is, the rod 2211 rotates in the direction of the arrow H in FIG. The rotating direction (arrow H in FIG. 11) is a direction that follows the conveying direction G of the negative electrode core material NB.

2. Rod Here, the rod 2211 of this embodiment will be described. The rod 2211 has a cylindrical shape. The outer diameter of the cylinder is about 5 to 20 mm. The material of the rod 2211 is, for example, aluminum. Other materials may also be used.

  A large number of non-through holes are formed on the surface of the rod 2211. These non-through holes are the same as the non-through holes 1211a formed in the gravure roll 1211 of FIG. That is, the average diameter of the non-through holes is 0.3 to 2.0 μm. The average depth of the non-through holes is 1 to 15 μm. The non-through-hole area sum W with respect to the non-through-hole area | region area V in the rod 2211 is in the range of 20 to 70%.

3. Battery Manufacturing Method The other configuration of the electrode plate manufacturing apparatus 2000 is the same as that of the first embodiment. The battery manufacturing method is almost the same. That is, instead of using the electrode plate manufacturing apparatus 1000 of the first embodiment, only the electrode plate manufacturing apparatus 2000 of this embodiment is used.

4). Modifications In this embodiment, all modifications described in the first embodiment can be applied. There is no change in the effect.

5. Summary As described above in detail, the electrode plate manufacturing apparatus 2000 according to the present embodiment includes the rod coating apparatus 2210 and the die coating apparatus 1250. The electrode plate manufacturing apparatus 2000 includes a rod 2211 in which fine non-through holes are formed. Since the non-through holes are fine, a paste layer of a binder solution having a thin coating thickness can be applied. Thereby, the electrode plate manufacturing apparatus 2000 which can produce the positive electrode plate PX and the negative electrode plate NX with sufficient peel strength is realized.

  Moreover, the manufacturing method of the battery of this embodiment is a method having an electrode plate creation step. In the electrode plate preparation process, the binder solution is thinly applied to the electrode core material using the rod 2211 having a large number of non-through holes formed by electrolytic etching, and the coating solution is applied thereon by a die coating apparatus. Work and dry. Therefore, the positive electrode plate P and the negative electrode plate N having sufficient peel strength between the electrode core material and the coating layer can be manufactured. Therefore, in the battery manufacturing method of the present embodiment, a battery with high peel strength of the coating layer on the positive electrode plate P and the negative electrode plate N can be manufactured.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, the material of the rod is not limited to aluminum. Other materials may be used as long as the material can form many non-through holes by electrolytic etching.

  It can also be applied to batteries that do not have an axial core. Moreover, it is not restricted to a cylindrical battery. A battery using a wound electrode body can be similarly applied. For example, the present invention can be applied to a battery cell that does not have an axial core inside the battery cell. Further, the present invention can also be applied to a rectangular battery having a flat wound electrode body that is produced by flat pressing the wound electrode body. Further, the present invention can also be applied to a battery using an electrode body in which a positive electrode plate and a negative electrode plate are stacked without winding. Moreover, it is not restricted to a lithium ion secondary battery. The present invention can also be applied to nickel metal hydride batteries and other secondary batteries. Moreover, if it is a battery, it can apply not only to a secondary battery but to a primary battery.

DESCRIPTION OF SYMBOLS 10 ... Battery 11 ... Battery container 12 ... Cover 100 ... Winding electrode body 110 ... Positive electrode current collecting plate 120 ... Negative electrode current collecting plate 1000, 2000 ... Electrode plate manufacturing apparatus 1100 ... Unwinding part 1101 ... Unwinding reel 1200, 2200 ... Coating unit 1210 ... Gravure coating device 1211 ... Gravure roll 1211a ... Non-through hole 1212 ... Liquid tank 1213 ... Doctor blade 1214, 1215 ... Guide roller 1230 ... Gravure roll 1231 ... Outer peripheral part 1231a ... Non-through hole 1232 ... Inner shaft part DESCRIPTION OF SYMBOLS 1250 ... Die coating apparatus 1251 ... Coating die 1252 ... Backup roller 1300 ... Drying furnace 1301 ... Air nozzle 1302 ... Roller 1400 ... Winding part 1401 ... Winding reel 2210 ... Rod coating apparatus 2211 ... Rod 2212 ... Support member 3000 ... Winding device 3001 ... Positive electrode plate Supply unit 3002 ... Negative electrode plate supply unit 3003, 3004 ... Separator supply unit 3005 ... Winding shafts P, PX ... Positive electrode plate PA ... Positive electrode mixture layer PB ... Positive electrode core material P1 ... Positive electrode coating unit P2 ... Positive electrode non-coating unit N, NX ... negative electrode plate NA ... negative electrode composite layer NB ... negative electrode core material N1 ... negative electrode coating part N2 ... negative electrode non-coating part NA1 ... binder solution layer NA2 ... negative electrode coating liquid layer S, T ... separator

Claims (6)

An unwinding section for unwinding the electrode core material;
A first coating device for applying a first coating liquid on one surface of the electrode core material to form a first paste layer;
A second coating device for applying a second coating liquid on the first paste layer of the electrode core material to form a second paste layer;
A drying furnace for drying the first paste layer and the second paste layer of the electrode core material while conveying the electrode core material;
An electrode plate manufacturing apparatus having a winding unit for winding an electrode core material obtained by drying the first paste layer and the second paste layer,
The first coating device is:
Have a large number of the coating roller blind holes are formed on the surface by electrolytic etching, the average diameter of the non-through holes formed in the roller for the coating is 0.3 to 2.0 .mu.m,
The average depth of the non-through holes formed in the coating roller is 1 to 15 μm,
The coating for the ratio occupied by the sum of the areas of the individual blind holes with respect to the total area of the region where the non-through hole is formed in the roller electrode plate manufacturing apparatus according to claim 20% to 70% der Rukoto . The electrode plate manufacturing apparatus according to claim 1 ,
The first coating device is:
A gravure roll is used as the coating roller,
An electrode plate manufacturing apparatus, characterized in that the gravure roll is rotated in the opposite direction to the direction in which the electrode core material is conveyed. The electrode plate manufacturing apparatus according to claim 1 ,
The first coating device is:
A rod is used as the coating roller,
An electrode plate manufacturing apparatus, characterized in that the rod is rotated in a direction following the conveying direction of the electrode core material. An electrode plate forming step of applying a coating liquid to the electrode core material to obtain a paste layer and drying the paste layer while being conveyed in a drying furnace to obtain a positive electrode plate or a negative electrode plate;
An electrode body preparation step in which a positive electrode plate and a negative electrode plate are electrode bodies with a separator interposed therebetween,
A battery manufacturing method comprising a battery assembly step in which an electrode body is disposed inside a battery container and an electrolytic solution is injected into the battery container and sealed.
In the electrode plate making process,
A first coating step of applying a first coating liquid to the electrode core material to form a first paste layer;
A second coating step of applying a second coating liquid on the first paste layer of the electrode core material to form a second paste layer;
In the first coating process,
Coating is performed using a coating roller with many non-through holes formed on the surface by electrolytic etching ,
As the coating roller,
The average diameter of the formed non-through holes is 0.3 to 2.0 μm,
The average depth of the formed non-through holes is 1 to 15 μm,
What is claimed is: 1. A method for manufacturing a battery, comprising using a cell having a ratio of the total area of individual non-through holes of 20 to 70% to the total area of a region where non-through holes are formed . A method of manufacturing a battery according to claim 4 ,
In the first coating process,
A method for producing a battery, characterized in that the coating roller is rotated in a direction opposite to the direction in which the electrode core material is conveyed. A method of manufacturing a battery according to claim 4 ,
In the first coating process,
A method for producing a battery, characterized in that the coating roller is rotated in a direction following the conveying direction of the electrode core material.

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