JP7293271B2 - Electrode plate manufacturing method - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to a method for manufacturing an electrode plate.

2. Description of the Related Art Conventionally, as an electrode plate in a battery or the like, one having a collector foil and an electrode layer on the surface thereof has been used. An electrode plate is generally manufactured by coating an electrode layer on a collector foil. A portion of the current collector foil is a non-coated portion having no electrode layer. This is due to the current collecting structure in the battery. In some cases, the electrode plate coated with the electrode layer is pressed for charge/discharge performance when assembled in a battery.

As the technology of the press, the one described in Patent Document 1 can be mentioned. In the technique of the same document, a wrinkle prevention device is installed on the entry side of the roll press machine that presses the coated part. The wrinkle prevention device is a device that prevents the occurrence of wrinkles and warpage in the electrode plate by pressing the non-coated portion. This is because uneven elongation of the current collector foil caused by pressing with a roll press acting only on the coated portion causes wrinkles and warping.

JP 2019-102172 A

The conventional techniques described above have the following problems. In some cases, the wrinkle preventing device may rather damage the collector foil. The reason for this is that the current collector foil cannot be easily stretched by pressing. This is because the current collector foil is a very thin metal foil, so even if there is a slight misalignment between the upper and lower press rolls, the load is not properly applied.

The disclosed technology has been made to solve the problems of the conventional technology described above. That is, the object is to provide a method for manufacturing an electrode plate by appropriately pressing the non-coated portion to manufacture an electrode plate with less uneven elongation between the coated portion and the non-coated portion. It is in.

A method for manufacturing an electrode plate according to one aspect of the disclosed technology has a collector foil and an electrode layer on the surface thereof, and a part in the width direction is a coated part having both the collector foil and the electrode layer. In addition, a method of manufacturing an electrode plate in which the remainder in the width direction is a non-coated portion having a current collecting foil and no electrode layer, comprising this pressing step of pressing the coated portion in the thickness direction; Straightening that reduces the difference in elongation between the coated and uncoated current collector foils after the pressing process by pressing the uncoated current collector foil before or after the pressing process. In the straightening press process, between the current collector foil and a press member for pressing the current collector foil, an elastic body made of synthetic resin having a lower elastic modulus than that of the current collector foil is placed at least at the current collector. This is due to pressing while sandwiching the foil on one side. Of course, it is more preferable to perform the straightening press process while sandwiching the elastic bodies on both sides of the current collector foil.

In the electrode plate manufacturing method of the above aspect, the electrode plate is subjected not only to the main pressing step but also to the correction pressing step. In the straightening press process, the current collector foil in the non-coated portion is reliably pressed and stretched by pressing through an elastic body. As a result, after both the main pressing process and the straightening pressing process are performed, the current collector foil elongation is not greatly different between the coated part and the non-coated part. Relaxation of the difference in elongation by the straightening press process may be performed after or before the main press process.

According to the disclosed technology, there is provided a method for manufacturing an electrode plate that can produce an electrode plate with less uneven elongation between the coated portion and the non-coated portion by appropriately pressing the non-coated portion. .

1 is a perspective view of an electrode plate manufactured in an embodiment; FIG. It is a schematic diagram which shows this press process. It is a schematic diagram which shows a straightening press process. It is a figure which shows the structural example of the apparatus which performs the correction press process of this form. It is a perspective view which shows the procedure of the elongation test by a correction|amendment press process. 10 is a graph showing the results of the first test; 10 is a graph showing the results of a second test; 10 is a graph showing the results of the third test;

Embodiments embodying the disclosed technology will be described in detail below with reference to the accompanying drawings. This embodiment embodies the disclosed technique as a method of manufacturing the electrode plate 1 shown in FIG. The electrode plate 1 of FIG. 1 has a collector foil 2 and an electrode layer 3 on its surface. In the electrode plate 1, a part in the width direction is a coating part 4 having both the current collector foil 2 and the electrode layer 3, and the remaining part in the width direction has the current collector foil 2 and the electrode layer 3. The non-coated portion 5 is not coated. There are non-coated portions 5 near both ends in the width direction of the electrode plate 1 , and the rest including the center is the coated portion 4 .

In this embodiment, the case where the electrode plate 1 is a positive electrode plate of a lithium ion battery will be described. Therefore, the collector foil 2 is aluminum foil, and the main component of the electrode layer 3 is nickel-cobalt-lithium-manganese oxide. In this embodiment, the electrode plate 1 is completed by performing the following two pressing processes on the starting material, which is the state in which the electrode layer 3 has been formed on the surface of the current collecting foil 2. . An electrode plate that has not undergone these two pressing processes is sometimes called an electrode plate 1, but it is incomplete in the technology of the present disclosure.
1. Main pressing process2. Straightening press process

This pressing step is a step of pressing the coating portion 4 of the electrode plate 1 in the thickness direction (FIG. 2). This is done to improve the charge/discharge performance of the electrode plate 1 by increasing the density of the electrode layer 3 . The straightening press process is a process of pressing the collector foil 2 in the non-coated portion 5 of the electrode plate 1 in the thickness direction (FIG. 3). Either the main pressing step or the straightening pressing step may be performed first.

The reason why the straightening press process is performed in addition to the main press process is to alleviate the non-uniform elongation of the current collector foil 2 . In this pressing step, as described above, the coated portion 4 is pressed in the thickness direction. It is mainly the electrode layer 3 that is compressed by this. The stiffer collector foil 2 compresses less than the electrode layer 3 . However, it is not compressed at all, but compressed somewhat. Therefore, there is a difference in the elongation rate between the collector foil 2 in the non-coated portion 5 that is not compressed at all and the collector foil 2 in the coated portion 4 that is slightly compressed. In order to prevent the collector foil 2 from being damaged or deformed due to the difference in elongation rate, a straightening press process is performed.

For this reason, in the straightening pressing step, the collector foil 2 in the non-coated portion 5 is pressed from the front and back sides by a pair of pressure rolls 6, as shown in FIG. As a result, the collector foil 2 of the non-coated portion 5 is pressed in the thickness direction. The pressure roll 6 is a pressing member that presses the collector foil 2 . By performing this straightening press process together with the main press process, the elongation of the current collector foil 2 in the non-coated part 5 and the current collector foil 2 in the coated part 4 is greater than when only the main press process is performed. It reduces the difference in rates.

In the straightening press process of this embodiment, as shown in FIG. The elastic body 7 is made of a material having a lower elastic modulus than the collector foil 2, such as synthetic resin. The pressure roll 6 itself is made of metal, and the elastic body 7 is made of a material having a lower elastic modulus than that of the pressure roll 6 . By sandwiching the elastic member 7, the correction press process can be properly performed without damaging the current collector foil 2. FIG.

If the correcting press process is performed by directly compressing the current collecting foil 2 with the pressure rolls 6 without the elastic body 7, it is difficult to properly perform the correcting press process. This is because if the pressure roll 6 is even slightly misaligned, the load cannot be properly applied to the entire current collector foil 2 in the non-coated portion 5 . Even if the alignment is correct and the load can be appropriately applied, the metal-to-metal contact causes part of the aluminum of the current collector foil 2 to peel off and generate fine powder. In this embodiment, such a situation is prevented by interposing the elastic body 7 .

FIG. 4 shows an example of the configuration of an apparatus for carrying out the straightening press process of this embodiment. The apparatus of FIG. 4 has a film supply section 8 and a film collection section 9 in addition to the pair of pressure rolls 6 . A film supply unit 8 and a film collection unit 9 are provided above and below the electrode plate 1 to be pressed, respectively. The resin film 10 supplied from the film supply unit 8 on the upper side is recovered by the film recovery unit 9 on the upper side, and the resin film 10 supplied from the film supply unit 8 on the lower side is recovered by the film recovery unit 9 on the lower side. In this device, a resin film 10 is used as the elastic body 7 in FIG. As is clear from the comparison with FIG. 3, in an actual device, two sets of components shown in FIG. 4 exist in parallel in the direction perpendicular to the paper surface. If the target electrode plate 1 is to be multi-coated, a larger number of sets are used in parallel.

In this apparatus, while the electrode plate 1 is passed between the pair of pressure rolls 6, the upper resin film 10 is placed between the upper pressure roll 6 and the electrode plate 1, and the lower resin film 10 is placed below. pass between the pressure roll 6 and the electrode plate 1, respectively. In this state, a pair of pressure rolls 6 are passed through the electrode plate 1 while pressing the electrode plate 1, thereby performing a correction pressing step. The device configuration of FIG. 4 is based on the premise that the resin film 10 can be used only once. When a resin film 10 having a certain degree of durability is used, it is possible to configure the apparatus so that it can be used several times. The above-described main pressing process is performed on the upstream side or downstream side of the apparatus of FIG.

Test results regarding the effect of the straightening press process will be described below. In this test, strip-shaped aluminum foil was used as a test piece corresponding to the current collector foil, and was subjected to the same press as the straightening press process. At that time, the elongation rate of the aluminum foil was measured before and after pressing. More specifically, a first test comparing the elongation rate by changing the type of the elastic body 7, a second test comparing the elongation rate by changing the pressing force of the press, and a thickness of the elastic body 7 A third test in which the elongation rate is compared by changing the

Specifically, the procedure shown in FIG. 5 was followed. That is, first, a test piece (aluminum foil) 11 is provided with two markings 12 spaced apart in the stretching direction, and the interval A between the markings 12 is measured. Then, the test piece 11 is placed between the two elastic bodies 7 and superimposed, and the laminate of the test piece 11 and the elastic body 7 is pressed from the front and back sides by a pair of pressure rolls 6 . After pressing, the elastic body 7 is removed and the interval B between the markings 12 is measured. A new elastic body 7 was used each time. The distance A is the length before pressing, the distance B is the length after pressing, and the elongation rate is calculated by the following equation.
Elongation rate = (B - A) / A

Various conditions for the test will be explained. First, the items common to the first test and the second test will be described.
Diameter of pressure roll 6: 100 mm
Thickness of test piece 11: 12 μm (before pressing)
Conveyance speed of test piece 11: 1.6 cm/second Number of passes: 1 time

A first test will be described. In the first test, the elastic bodies 7 made of four types of resin materials were prepared, and elongation rates were measured for a total of five levels of these and no elastic bodies. The pressing force (linear pressure) of the press was 5 kN/cm. The thickness of the elastic body 7 was 100 μm (before pressing).

The types of resin materials used for the elastic body 7 and their Young's moduli (compressive elastic moduli) are shown in Table 1 (values measured by the inventors). All of these resin materials are aluminum, which is the material of the current collector foil 2 and the test piece 11. ) has a lower elastic modulus.

The results of the first test were as shown in FIG. FIG. 6 shows the elongation rate of the test piece 11 for each type of resin material ("none" indicates no elastic body). Significantly higher elongation rate is obtained compared to "none" when using any of the four types of resin materials. This means that the use of the elastic body 7 can reduce the above-mentioned adverse effects that occur when there is no elastic body. FIG. 6 also shows that the smaller the value of the Young's modulus of the resin material used, that is, the higher the flexibility, the higher the elongation. From this, it can be seen that a higher effect can be obtained by using an elastic body made of a flexible material.

A second test will be described. In the second test, the pressing force of the press was set at three levels and the elongation at each pressing force was measured. As the material of the elastic body 7 in the second test, one of the four types of PVC was used. The thickness of the elastic body 7 was set to 100 μm (before pressing) as in the first test.

The results of the second test were as shown in FIG. FIG. 7 shows the elongation rate of the test piece 11 for each level of pressing force of the press. It can be seen from FIG. 7 that the higher the pressing force, the higher the elongation rate. The highest pressing force among the three levels in FIG. 7 is the same as the pressing force in the first test described above. According to FIG. 7, it can be seen that a significantly higher elongation rate can be obtained compared to "none" in FIG. 6 even if the pressing force is lower than that. It is considered that the same tendency is observed even when the elastic body 7 of a type other than PVC is used.

A third test will be described. In the third test, the thickness of the elastic body 7 was set at three levels and the elongation rate was measured for each. As the material of the elastic body 7 in the third test, PET, which is one of the four types described above, was used. The pressing force of the press was 5 kN/cm as in the first test.

The results of the third test were as shown in FIG. FIG. 8 shows the elongation rate of the test piece 11 for each thickness of the elastic body 7 . As can be seen from FIG. 8, the thicker the elastic body 7, the higher the elongation rate. The thickness of 100 μm, which is the thickest among the three levels in FIG. 8, is the same as the thickness of the elastic body 7 in the first test described above. According to FIG. 8, it can be seen that a significantly higher elongation rate can be obtained compared to "none" in FIG. 6 even when the thinner elastic body 7 is used. It is considered that the same tendency is observed even when the elastic body 7 of a type other than PET is used.

The first, second, and third tests described above were performed only by pressing corresponding to the corrective press process, and were not performed by combining this press process and the corrective press process. However, from the first to third tests, it can be seen that the elongation rate of the collector foil 2 in the non-coated portion 5 can be controlled by selecting the material and thickness of the elastic body and setting the pressing force of the press. From this, it can be seen that if the elongation rate of the collector foil 2 of the coated portion 4 in the present press process is known in advance, the conditions of the straightening press process can be selected according to it. As a result, the difference in the elongation rate of the current collector foil 2 between the non-coated portion 5 and the coated portion 4 after both the main pressing process and the straightening pressing process are performed on the electrode plate 1 can be minimized. can be

As described in detail above, according to the present embodiment, the main pressing for pressing the coated portion 4 against the electrode plate 1 in a state where the electrode layer 3 on the surface of the current collecting foil 2 has been formed. and a straightening press step of pressing the non-coated portion 5. In the straightening press step, the collector foil 2 is pressed via the elastic body 7. FIG. As a result, the non-coated portion 5 is appropriately pressed, and the electrode plate 1 can be manufactured in which the non-uniform elongation of the collector foil 2 between the coated portion 4 and the non-coated portion 5 is small. has been realized. In the electrode plate 1 completed through the method of the present embodiment, the possibility of wrinkling, warping, or breaking of the current collecting foil 2 is extremely low.

The present embodiments and examples are merely examples, and do not limit the disclosed technology in any way. Therefore, the disclosed technique can naturally be improved and modified in various ways without departing from the gist thereof. For example, the type of target electrode plate is not limited to the positive electrode plate of the lithium ion battery, and may be other types. Even if the elastic body is interposed only on one side of the electrode plate, there is some effect and it is included in the scope of the disclosed technology. The apparatus configuration for performing the straightening press process is not limited to that shown in FIG. When a durable resin film 10 is used, the resin film 10 may be circulated so that it can be used repeatedly for a certain number of times.

1 Electrode plate 2 Current collector foil 3 Electrode layer 4 Coated part 5 Non-coated part 6 Pressure roll 7 Elastic body

Claims (1)

It has a collector foil and an electrode layer on its surface, and a part in the width direction is a coating part having both the collector foil and the electrode layer, and the rest in the width direction is the collector foil. A method for manufacturing an electrode plate, which is a non-coated portion having no electrode layer, comprising:
A main pressing step of pressing the coated portion in the thickness direction;
By pressing the current collector foil of the non-coated portion before or after the main pressing step, the current collector foil of the coated portion and the current collector of the non-coated portion after the main pressing step Perform a straightening press process to reduce the difference in elongation with the foil,
In the correction pressing step, an elastic body made of synthetic resin having a lower elastic modulus than the current collector foil is placed between the current collector foil and a pressing member for pressing the current collector foil. A method for manufacturing an electrode plate in which pressing is performed while sandwiching on one side of

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