Method for manufacturing electrode plate and method for manufacturing battery

Abstract

Provided are a method for manufacturing a plate having reduced variation in performance and a method for manufacturing a battery. A method for manufacturing a plate, which is a method for manufacturing a plate including a current collector and an active material layer, includes: producing a composite material by mixing an active material; forming the active material layer on the current collector by applying the composite material to the current collector; and pressing the active material layer to make the active material layer a prescribed thickness, the composite material being applied to the current collector in an amount per unit area based on a specific surface area of the active material used in the composite material and a tap density of the active material used in the composite material.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for manufacturing an electrode plate and a method for manufacturing a battery. BACKGROUND

[0002] A battery provided with an electrode plate is described in Patent Literature 1. The electrode plate includes a current collector and an active material layer on the current collector. The active material layer is formed, for example, by applying a composite material including an active material to the current collector. Pressing is performed after the active material layer is formed on the current collector. Thereby, the electrode plate is manufactured.

[0003] In Patent Literature 1, it is described that the specific surface area of the active material included in the active material layer affects the performance of the electrode plate, and that the specific surface area of the active material included in the active material layer increases by pressing the active material layer.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 10-116604 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] In the active material used in the composite material, there can be a variation in physical properties. For example, even if it is the same kind of active material, the specific surface area, tap density, and the like can be different. If the physical properties of the active material used in the composite material are different, the amount of increase in the specific surface area of the active material included in the active material layer can be different even if the active material layer is pressed under the same conditions. Therefore, if the physical properties of the active material are different in each of the composite materials, the performance of the electrode plate can vary.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] The method for manufacturing an electrode plate of one aspect of the present disclosure is a method for manufacturing an electrode plate including a current collector and an active material layer, which includes: preparing a composite material by kneading an active material; forming the active material layer on the current collector by applying the composite material to the current collector; and pressing the active material layer to make the active material layer a prescribed thickness, the composite material being applied to the current collector in an amount per unit area based on the specific surface area of the active material used in the composite material and the tap density of the active material used in the composite material.

[0011] In the manufacturing method of the electrode plate, in the case where the electrode plate is manufactured from the composite material using the active material having the specific surface area of the first area, the amount per unit area of the composite material can be reduced as compared with the case where the electrode plate is manufactured from the composite material using the active material having the specific surface area of the second area smaller than the first area.

[0012] In the manufacturing method of the electrode plate, in the case where the electrode plate is manufactured from the composite material using the active material having the specific surface area of the first area and the tap density of the first density, the amount per unit area of the composite material can be reduced as compared with the case where the electrode plate is manufactured from the composite material using the active material having the specific surface area of the first area and the tap density of the second density larger than the first density.

[0013] In the manufacturing method of the electrode plate, in the case where the electrode plate is manufactured from the composite material using the active material having the specific surface area of the second area and the tap density of the first density, the amount per unit area of the composite material can be reduced as compared with the case where the electrode plate is manufactured from the composite material using the active material having the specific surface area of the second area and the tap density of the second density larger than the first density.

[0014] The manufacturing method of the battery according to another aspect of the present application is a manufacturing method of a battery provided with an electrode plate including a current collector and an active material layer, which includes: producing a composite material by kneading an active material; forming the active material layer on the current collector by applying the composite material to the current collector; and pressing the active material layer so that the active material layer becomes a prescribed thickness, the composite material being applied to the current collector in an amount per unit area based on the specific surface area of the active material used in the composite material and the tap density of the active material used in the composite material.

[0015] Effects of the Invention

[0016] According to the present application, the performance deviation of the electrode plate can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a perspective view of a group battery.

[0018] Figure 2 is a view obtained by unfolding a part of an electrode body.

[0019] Figure 3 is a flowchart showing a manufacturing method of an electrode plate.

[0020] Figure 4 is a table showing the properties of an active material.

[0021] Figure 5 This is a graph showing the thickness of the active material layer when the unit area of ​​each composite material is the same.

[0022] Figure 6 This is a graph showing the relationship between the displacement of the active material layer caused by pressing and the increase in the specific surface area of ​​the active material caused by pressing.

[0023] Figure 7 This is a graph showing the increase or decrease in the specific surface area of ​​the active material when the unit area amount of each composite material is the same.

[0024] Figure 8 This is a graph showing the thickness of the active material layer for different amounts per unit area of ​​each composite material, based on the physical properties of the active material.

[0025] Figure 9 This is a graph showing the increase or decrease in the specific surface area of ​​the active material based on its physical properties, with different amounts per unit area for each composite material.

[0026] Figure 10 This is a table showing the displacement of the thickness of the active material layer due to pressing and the increase in the specific surface area of ​​the active material due to pressing in each composite material. Detailed Implementation

[0027] The manufacturing methods of the electrode plates and the battery will be described with reference to the accompanying drawings. First, a battery having electrode plates will be described. For example, a lithium-ion secondary battery. However, the battery is not limited to this; for example, it could also be an alkaline secondary battery or other types of batteries.

[0028] like Figure 1 As shown, the battery 10 includes a casing 11 and a cover 12 that blocks the opening of the casing 11. The battery 10 includes a positive terminal 13 and a negative terminal 14. The positive terminal 13 and the negative terminal 14 extend from the cover 12.

[0029] The battery 10 includes an electrode body 15. The electrode body 15 is located inside a casing 11. The electrode body 15 and the electrolyte are housed together in the casing 11. The electrode body 15 is connected to the positive terminal 13 and the negative terminal 14. The shapes of the positive terminal 13 and the negative terminal 14 are not limited to... Figure 1 The shape shown can also be other shapes.

[0030] like Figure 2As shown, the electrode body 15 includes the positive electrode plate 16, the negative electrode plate 17, the separator 18, and the separator 19. The electrode body 15 is a laminate in which the positive electrode plate 16, the negative electrode plate 17, the separator 18, and the separator 19 are overlapped and wound. The positive electrode plate 16, the separator 18, the negative electrode plate 17, and the separator 19 are overlapped and wound in a state of being sequentially laminated. The separator 18 and the separator 19 are, for example, nonwoven fabric made of resin.

[0031] The positive electrode plate 16 includes a positive electrode current collector 21 and a positive electrode active material layer 22. The positive electrode current collector 21 is, for example, a metal foil. The positive electrode current collector 21 is, for example, composed of a material including aluminum.

[0032] The positive electrode current collector 21 has a connection portion 23. The connection portion 23 is a portion that is electrically connected to the positive electrode terminal 13. The connection portion 23 is located at an end portion of the positive electrode current collector 21. The connection portion 23 is a portion in which the positive electrode active material layer 22 is not present in the positive electrode current collector 21.

[0033] The positive electrode active material layer 22 is located on the positive electrode current collector 21. The positive electrode active material layer 22 is located on one face or both faces of the positive electrode current collector 21. The positive electrode active material layer 22 includes a positive electrode active material. The positive electrode active material layer 22 is formed by applying a composite material including the positive electrode active material to the positive electrode current collector 21.

[0034] The positive electrode active material is, for example, a material capable of intercalating and deintercalating lithium. The positive electrode active material is, for example, a lithium-containing composite oxide. The lithium-containing composite oxide is an oxide including lithium and other metal elements other than lithium.

[0035] The negative electrode plate 17 includes a negative electrode current collector 24 and a negative electrode active material layer 25. The negative electrode current collector 24 is, for example, a metal foil. The negative electrode current collector 24 is, for example, composed of a material including copper.

[0036] The negative electrode current collector 24 has a connection portion 26. The connection portion 26 is a portion that is electrically connected to the negative electrode terminal 14. The connection portion 26 is located at an end portion of the negative electrode current collector 24. The connection portion 26 is a portion in which the negative electrode active material layer 25 is not present in the negative electrode current collector 24.

[0037] The negative electrode active material layer 25 is located on the negative electrode current collector 24. The negative electrode active material layer 25 is located on one face or both faces of the negative electrode current collector 24. The negative electrode active material layer 25 includes a negative electrode active material. The negative electrode active material layer 25 is formed by applying a composite material including the negative electrode active material to the negative electrode current collector 24.

[0038] The negative electrode active material is, for example, a material capable of intercalating and deintercalating lithium. The negative electrode active material is, for example, a carbon material. The negative electrode active material is, for example, graphite such as natural graphite or artificial graphite.

[0039] Next, the manufacturing method of the electrode plates will be described. The manufacturing method of the electrode plates is the same as that of the positive electrode plate 16 and the negative electrode plate 17. The materials used in the positive electrode plate 16 and the negative electrode plate 17 are different, but the manufacturing method is the same. Therefore, in the following text, the positive electrode plate 16 and the negative electrode plate 17 will sometimes be referred to as electrode plates, the positive current collector 21 and the negative current collector 24 will sometimes be referred to as current collectors, the positive active material layer 22 and the negative active material layer 25 will sometimes be referred to as active material layers, and the positive active material and the negative active material will sometimes be referred to as active materials.

[0040] like Figure 3 As shown, firstly, in step S11, a composite material is produced by mixing the active substances. For example, the composite material is produced by mixing the active substances using a mixing machine. The composite material can be produced by mixing the active substances, as well as materials such as binders, solvents, conductive agents, and dispersants. In this example, the composite material is produced by mixing the active substances, binders, and solvents. The binder is a material used to improve the adhesion between the active substances. The conductive agent is a material used to impart conductivity to the composite material. The dispersant is a material used to uniformly disperse the active substances. When the composite material is produced by mixing only the active substances, the active substances are preferably adhesive materials. A paste-like composite material is produced through the process in step S11.

[0041] It should be noted that, in addition to the above, other materials such as thickeners can also be mixed in.

[0042] Next, in step S12, the composite material is coated onto the current collector. For example, the composite material is coated onto the current collector using a coating device such as a slot coater or a die coater. Through the process in step S12, an active material layer is formed on the current collector.

[0043] The composite material is coated onto the current collector at a predetermined unit area amount. "Unit area amount" refers to the mass per unit area. The unit area amount is varied by controlling the coating device. When the composite material is coated onto the current collector, a first-thickness active material layer is formed. This first thickness is determined by the unit area amount of the composite material.

[0044] Next, in step S13, the active material layer is pressed. For example, the active material layer is pressed using a press. At this time, the press presses the current collector and the active material layer. The electrode plate is manufactured through the process in step S13. By manufacturing the electrode body 15 from this electrode plate, the battery 10 can be manufactured.

[0045] The active material layer is pressed to be a predetermined second thickness. The second thickness is changed by controlling the press. When the active material layer is pressed, the active material layer is compressed from the first thickness to the second thickness. That is, the first thickness is the thickness of the active material layer before the pressing. The second thickness is the thickness of the active material layer after the pressing.

[0046] In the process of manufacturing the electrode plate, the active material layer can be dried. The active material layer can be dried after the pressing or before the pressing. For example, the active material layer can be dried by blowing hot air or by being placed in a vacuum.

[0047] The performance of the battery 10 depends on the performance of the electrode plate. The performance of the electrode plate is determined by the reaction area of the electrode plate. Therefore, when the electrode plate is manufactured, it is important to reduce the deviation of the reaction area of the electrode plate. The reaction area of the electrode plate depends on the specific surface area of the active material included in the active material layer.

[0048] In the active material used in the production of the composite material, the physical properties can have a deviation. For example, in each batch provided by the supplier, the physical properties of the active material can be different. Specifically, the specific surface area of the active material, the tap density of the active material can be different. If the physical properties of the active material have a deviation, the performance of the electrode plate can have a deviation.

[0049] As shown in Figure 4 , a first active material, a second active material, a third active material, and a fourth active material are considered, each of which has different physical properties. The first active material, the second active material, the third active material, and the fourth active material are each the same kind of active material. In the first active material, the specific surface area is a first area, and the tap density is a first density. In the second active material, the specific surface area is the first area, and the tap density is a second density. In the third active material, the specific surface area is a second area, and the tap density is the first density. In the fourth active material, the specific surface area is the second area, and the tap density is the second density. The first area is larger than the second area. The first density is smaller than the second density.

[0050] Next, a case where an electrode plate is manufactured from a composite material using the first active material, a composite material using the second active material, a composite material using the third active material, and a composite material using the fourth active material is considered. In the composite material using the first active material, the composite material using the second active material, the composite material using the third active material, and the composite material using the fourth active material, only the physical properties of the active material are different from each other, and other materials used, the weight ratio of the materials, etc. are the same, and the mass of the active material is also the same.

[0051] As shown in Figure 5When the composite material using the first active material, the composite material using the second active material, the composite material using the third active material, and the composite material using the fourth active material are coated to the current collector in the same unit area amount, respectively, the first thickness of the active material layer differs. Specifically, the first thickness of the active material layer containing the first active material and the first thickness of the active material layer containing the third active material are greater than the first thickness of the active material layer containing the second active material and the first thickness of the active material layer containing the fourth active material. This is due to the difference in tap density of the active material.

[0052] The smaller the tap density of the active material used in the composite material, the smaller the density of the composite material. Therefore, when the unit area amount of each of the composite materials is the same, the smaller the tap density of the active material used in the composite material, the greater the first thickness of the active material layer. Therefore, when the unit area amount of each of the composite materials is the same, the first thickness of the active material layer containing the active material with a small tap density is greater than the first thickness of the active material layer containing the active material with a large tap density.

[0053] The active material layer containing the first active material, the active material layer containing the second active material, the active material layer containing the third active material, and the active material layer containing the fourth active material are compressed to the second thickness by pressing, respectively. The second thickness is the same regardless of the physical properties of the active material used in the composite material. This is because, when the battery 10 is manufactured, the thickness of the electrode plate is fixed. In each of the composite materials used, if the thickness of the electrode plate is different, the thickness of the electrode body 15 is affected. In this case, the design of the battery 10 becomes complicated.

[0054] When the active material layer containing the first active material, the active material layer containing the second active material, the active material layer containing the third active material, and the active material layer containing the fourth active material are pressed, respectively, the displacement amount of the thickness of the active material layer due to the pressing differs. Specifically, the displacement amount of the thickness of the active material layer containing the first active material and the displacement amount of the thickness of the active material layer containing the third active material are greater than the displacement amount of the thickness of the active material layer containing the second active material and the displacement amount of the thickness of the active material layer containing the fourth active material.

[0055] The greater the first thickness, the greater the displacement amount of the thickness of the active material layer due to the pressing. Therefore, when the unit area amount of each of the composite materials is the same, the smaller the tap density of the active material used in the composite material, the greater the displacement amount of the thickness of the active material layer due to the pressing.

[0056] The specific surface area of the active material increases by pressing the active material layer. This is believed to be due to a change in the shape of the active material contained in the active material layer by pressing the active material layer.

[0057] As shown in Figure 6 , the amount of increase in the specific surface area of the active material varies depending on the amount of displacement of the thickness of the active material layer due to pressing. Specifically, the greater the amount of displacement of the thickness of the active material layer due to pressing, the greater the amount of increase in the specific surface area of the active material. Therefore, with the same amount of the composite material per unit area, the smaller the tap density of the active material used in the composite material, the greater the amount of increase in the specific surface area of the active material due to pressing.

[0058] As shown in Figure 7 , the specific surface area of the active material is not limited to a change due to pressing, but also changes during the process of manufacturing the electrode plate. The specific surface area can be measured, for example, by the BET method.

[0059] The specific surface area of the active material before the composite material is manufactured is, for example, the specific surface area of the active material before being put into the kneader. The specific surface area of the first active material before the composite material is manufactured is the first area. The specific surface area of the second active material before the composite material is manufactured is the first area. The specific surface area of the third active material before the composite material is manufactured is the second area. The specific surface area of the fourth active material before the composite material is manufactured is the second area.

[0060] The specific surface area of the active material after the composite material is manufactured is the specific surface area of the active material contained in the composite material. As shown in Figure 7 , the specific surface area of the active material decreases after the composite material is manufactured compared to before the composite material is manufactured. This is believed to be due to a change in the surface shape of the active material by kneading. In addition, it is also believed that the covering of the active material by the binder is one of the reasons for the decrease in the specific surface area.

[0061] The specific surface area of the active material after coating is the specific surface area of the active material contained in the active material layer before pressing. The specific surface area of the active material after coating is almost unchanged or slightly decreased compared to after the composite material is manufactured.

[0062] The specific surface area of the active material after pressing is the specific surface area of the active material contained in the active material layer after pressing. The specific surface area of the active material after pressing increases compared to after coating. In the example shown in Figure 7 , the order of the specific surface area from large to small after pressing is the first active material, the second active material, the third active material, and the fourth active material.

[0063] Differences in the specific surface area of ​​the active material before composite material fabrication can easily lead to differences in the specific surface area of ​​the active material after pressing. Furthermore, differences in the tap density of the active material are related to differences in the increase in the specific surface area of ​​the active material due to pressing. Therefore, if the properties of the active materials used in the composite material are different, the specific surface area of ​​the pressed active material is prone to deviation. This deviation in the specific surface area of ​​the pressed active material is related to the deviation in the reaction area of ​​the electrode plate. Therefore, if the properties of the active materials used in the composite material are different, the performance of the electrode plate is prone to deviation.

[0064] like Figure 8 As shown, in this example, the unit area of ​​each composite material varies depending on the properties of the active material used in the composite material. For example, the user operates the coating apparatus, thereby changing the unit area of ​​the composite material according to the properties of the active material used in the composite material. Alternatively, the unit area of ​​the composite material can be automatically changed by specifying the properties of the active material used in the composite material through the coating apparatus.

[0065] The unit area of ​​the composite material using the first active ingredient is designated as the first unit area. The unit area of ​​the composite material using the second active ingredient is designated as the second unit area. The unit area of ​​the composite material using the third active ingredient is designated as the third unit area. The unit area of ​​the composite material using the fourth active ingredient is designated as the fourth unit area. The first, second, third, and fourth unit areas are listed in ascending order. That is, the first unit area is less than the second unit area. The second unit area is less than the third unit area. The third unit area is less than the fourth unit area.

[0066] In this example, the amount of surface area per unit area of ​​each composite material varies depending on the specific surface area of ​​the active material used in the composite material. Compared to the case where an electrode plate is manufactured using a composite material with an active material using a small specific surface area, the amount of surface area per unit area of ​​the composite material is smaller when an electrode plate is manufactured using an active material with a large specific surface area. For example, compared to the case where an electrode plate is manufactured using a composite material with an active material having a second specific surface area, the amount of surface area per unit area of ​​the composite material is smaller when an electrode plate is manufactured using a composite material with an active material having a first specific surface area. Specifically, compared to the case where an electrode plate is manufactured using a composite material with a third or fourth active material, the amount of surface area per unit area of ​​the composite material is smaller when an electrode plate is manufactured using a composite material with a first or second active material. Thus, in this example, the amount of surface area per unit area of ​​the composite material decreases when an electrode plate is manufactured using a composite material with an active material having a large specific surface area, and increases when an electrode plate is manufactured using a composite material with an active material having a small specific surface area.

[0067] As shown in Figure 9 If the amount per unit area of the composite material is changed, the increase in the specific surface area of the active material due to pressing is changed. In the case where the electrode plate is manufactured using the composite material using the active material having the first specific surface area, the increase in the specific surface area of the active material due to pressing is reduced by reducing the amount per unit area of the composite material, as compared with the case where the electrode plate is manufactured using the composite material using the active material having the second specific surface area. Specifically, in the case where the electrode plate is manufactured using the composite material using the first active material or the second active material, the increase in the specific surface area of the active material due to pressing is reduced by reducing the amount per unit area of the composite material, as compared with the case where the electrode plate is manufactured using the composite material using the third active material or the fourth active material.

[0068] In manufacturing the electrode plate, the amount per unit area of the composite material is changed in such a manner that the increase in the specific surface area of the active material due to pressing is reduced for the active material having a large specific surface area and the increase in the specific surface area of the active material due to pressing is increased for the active material having a small specific surface area. That is, in the case where the electrode plate is manufactured using the composite material using the active material having a large specific surface area, the amount per unit area of the composite material can be reduced in order to reduce the increase in the specific surface area of the active material due to pressing. In the case where the electrode plate is manufactured using the composite material using the active material having a small specific surface area, the amount per unit area of the composite material can be increased in order to increase the increase in the specific surface area of the active material due to pressing. Thus, the specific surface area of the active material is increased by pressing, so that the difference in the specific surface area of the active material is reduced. As a result, the deviation in the reaction area of the electrode plate is reduced.

[0069] As shown in Figure 8 In this example, the amount per unit area of each of the composite materials differs depending on the tap density of the active material used in the composite material, in addition to the specific surface area of the active material used in the composite material. Even if the specific surface area of the active material used in the composite material is the same, the density of the composite material differs if the tap density of the active material differs. Therefore, even if the specific surface area of the active material used in the composite material is the same and the amount per unit area of each of the composite materials is the same, the first thickness differs. Even if the specific surface area of the active material used in the composite material is the same, the increase in the specific surface area of the active material due to pressing easily differs if the tap density of the active material differs. Therefore, even if the specific surface area of the active material is the same before the composite material is manufactured, the specific surface area of the active material after pressing easily differs if the tap density of the active material differs.

[0070] In this example, the amount per unit area of the composite material is smaller in the case where the electrode plate is manufactured using the composite material using the active material having the specific surface area of the first area and the tap density of the first density than in the case where the electrode plate is manufactured using the composite material using the active material having the specific surface area of the first area and the tap density of the second density. Specifically, the amount per unit area of the composite material is smaller in the case where the electrode plate is manufactured using the composite material using the first active material than in the case where the electrode plate is manufactured using the composite material using the second active material. The difference in the increase in the specific surface area of the active material due to pressing is reduced by reducing the amount per unit area of the composite material in the case where the electrode plate is manufactured using the composite material using the first active material than in the case where the electrode plate is manufactured using the composite material using the second active material.

[0071] In this example, the amount per unit area of the composite material is smaller in the case where the electrode plate is manufactured using the composite material using the active material having the specific surface area of the second area and the tap density of the first density than in the case where the electrode plate is manufactured using the composite material using the active material having the specific surface area of the second area and the tap density of the second density. Specifically, the amount per unit area of the composite material is smaller in the case where the electrode plate is manufactured using the composite material using the third active material than in the case where the electrode plate is manufactured using the composite material using the fourth active material. The difference in the increase in the specific surface area of the active material due to pressing is reduced by reducing the amount per unit area of the composite material in the case where the electrode plate is manufactured using the composite material using the third active material than in the case where the electrode plate is manufactured using the composite material using the fourth active material.

[0072] In manufacturing the electrode plate, the amount per unit area of the composite material is changed in a manner that the increase in the specific surface area due to pressing is reduced for the active material having a small tap density and the increase in the specific surface area due to pressing is increased for the active material having a large tap density. Thus, the difference in the increase in the specific surface area of the active material due to pressing is reduced in the case where the electrode plate is manufactured using the composite material using the active material having the tap density of the first density and in the case where the electrode plate is manufactured using the composite material using the active material having the tap density of the second density. As a result, the deviation in the reaction area of the electrode plate is reduced.

[0073] In this example, in both cases where the electrode plate is manufactured from a composite material using a first active material and a composite material using a second active material, the unit area of ​​the composite material is adjusted to ensure a consistent first thickness. Therefore, in both cases, the displacement of the active material layer thickness due to pressing is consistent. Consequently, the increase in the specific surface area of ​​the active material due to pressing is consistent. As a result, the deviation in the reaction area of ​​the electrode plate is reduced.

[0074] In this example, in both cases where the electrode plate is manufactured using a composite material containing a third active material and a composite material containing a fourth active material, the unit area of ​​the composite material is adjusted to ensure a consistent first thickness. Therefore, in both cases where the electrode plate is manufactured using a composite material containing a third active material and a composite material containing a fourth active material, the displacement of the active material layer thickness due to pressing is consistent. Consequently, in both cases where the electrode plate is manufactured using a composite material containing a third active material and a composite material containing a fourth active material, the increase in the specific surface area of ​​the active material due to pressing is consistent. As a result, the deviation in the reaction area of ​​the electrode plate is reduced.

[0075] When the electrode plate is manufactured from a composite material using a first active material or a second active material, the displacement of the active material layer thickness due to pressing is the first displacement. When the electrode plate is manufactured from a composite material using a third active material or a fourth active material, the displacement of the active material layer thickness due to pressing is the second displacement. The first displacement is less than the second displacement.

[0076] like Figure 9 As shown, by changing the unit area of ​​the composite material based on tap density in addition to the specific surface area of ​​the active material used in the composite material, the difference between the specific surface area of ​​the first active material and the second active material after pressing is reduced. Similarly, by changing the unit area of ​​the composite material based on tap density in addition to the specific surface area of ​​the active material used in the composite material, the difference between the specific surface area of ​​the third active material and the fourth active material after pressing is reduced.

[0077] like Figure 10As shown, in the present example, in the case where the electrode plate is manufactured from the composite material using the first active material, the increase in the specific surface area of the active material due to the pressing is the first increase amount. In the case where the electrode plate is manufactured from the composite material using the second active material, the increase in the specific surface area of the active material due to the pressing is the first increase amount. In the case where the electrode plate is manufactured from the composite material using the third active material, the increase in the specific surface area of the active material due to the pressing is the second increase amount. In the case where the electrode plate is manufactured from the composite material using the fourth active material, the increase in the specific surface area of the active material due to the pressing is the second increase amount. The first increase amount is smaller than the second increase amount.

[0078] Among the third active material and the fourth active material, which have a large displacement amount of the thickness of the active material layer due to the pressing, cracking or collapse occurs by the pressing. Therefore, compared to the first active material and the second active material, the increase in the specific surface area of the third active material and the fourth active material due to the pressing is large.

[0079] By changing the amount per unit area of the composite material, the increase in the specific surface area of the active material due to the pressing can be changed. Thereby, even in the case where the physical properties of the active material used in the composite material have a deviation, it is possible to adjust the specific surface area of the active material after the pressing to a desired specific surface area. Therefore, by changing the amount per unit area of the composite material in accordance with the physical properties of the active material used in the composite material so that the specific surface area of the active material after the pressing, that is, the specific surface area of the active material included in the active material layer, is a desired specific surface area, it is possible to reduce the deviation in the reaction area of the electrode plate.

[0080] Next, the effects of the above-described embodiments will be described.

[0081] (1) The manufacturing method of the electrode plate includes producing a material by mixing an active material. The manufacturing method of the electrode plate includes forming an active material layer on a current collector by applying a composite material to the current collector. The manufacturing method of the electrode plate includes pressing the active material layer so that the active material layer becomes from a first thickness to a second thickness. The composite material is applied to the current collector in an amount per unit area based on the specific surface area of the active material used in the composite material and the tap density of the active material used in the composite material. The active material layer is pressed so that the thickness of the active material layer becomes a prescribed thickness (a uniform thickness).

[0082] The performance of the electrode plate is determined by the reaction area of the electrode plate. The reaction area of the electrode plate depends on the specific surface area of the active material included in the active material layer. By pressing the active material layer, the specific surface area of the active material included in the active material layer increases. The larger the displacement amount of the thickness of the active material layer due to the pressing, the larger the increase in the specific surface area of the active material included in the active material layer.

[0083] In a case where the active material layer is pressed to be a prescribed thickness, the amount of displacement of the thickness of the active material layer due to the pressing is determined by the thickness of the active material layer before the pressing. The thickness of the active material layer before the pressing affects the amount per unit area of the composite material coated to the current collector. The greater the amount per unit area of the composite material, the more likely the thickness of the active material layer before the pressing increases. That is, the greater the amount per unit area of the composite material, the more likely the amount of increase of the specific surface area of the active material due to the pressing increases.

[0084] If the tap densities of the active materials used in the composite materials are different, the thickness of the active material layer before the pressing can be different even if the amounts per unit area of each of the composite materials are the same. Specifically, the smaller the tap density of the active material used in the composite material, the more likely the thickness of the active material layer before the pressing increases, in a case where the amounts per unit area of each of the composite materials are the same. That is, the smaller the tap density of the active material used in the composite material, the more likely the amount of increase of the specific surface area of the active material due to the pressing increases, in a case where the amounts per unit area of each of the composite materials are the same.

[0085] According to the above-described method, the amount per unit area of each of the composite materials is different based on the specific surface area of the active material used in the composite material and the tap density of the active material used in the composite material, that is, the physical properties of the active material used in the composite material. The amount per unit area of the composite material affects the thickness of the active material layer before the pressing. The thickness of the active material layer before the pressing affects the amount of displacement of the thickness of the active material layer due to the pressing. The amount of displacement of the thickness of the active material layer due to the pressing affects the amount of increase of the specific surface area of the active material due to the pressing. Therefore, if the amount per unit area of the composite material is changed depending on the physical properties of the active material used in the composite material, the amount of increase of the specific surface area of the active material due to the pressing changes. That is, by adjusting the amount per unit area of the composite material depending on the physical properties of the active material used in the composite material, it is possible to adjust the amount of increase of the specific surface area of the active material due to the pressing. This reduces the deviation of the reaction area of the electrode plate. As a result, it reduces the deviation of the performance of the electrode plate.

[0086] (2) The amount per unit area of the composite material is smaller in a case where the electrode plate is manufactured using the composite material using the active material having the first area than in a case where the electrode plate is manufactured using the composite material using the active material having the second area smaller than the first area.

[0087] According to the above method, the amount per unit area of the composite material is small in the case where the electrode plate is manufactured from the composite material using the active material having the specific surface area of the first area, and the amount per unit area of the composite material is large in the case where the electrode plate is manufactured from the composite material using the active material having the specific surface area of the second area. Therefore, the amount of increase in the specific surface area of the active material due to the pressing is small in the case where the electrode plate is manufactured from the composite material using the active material having the specific surface area of the first area, as compared with the case where the electrode plate is manufactured from the composite material using the active material having the specific surface area of the second area. That is, the amount of increase in the specific surface area of the active material due to the pressing is small for the active material having the large specific surface area originally, and the amount of increase in the specific surface area of the active material due to the pressing is large for the active material having the small specific surface area originally. This reduces the deviation in the reaction area of the electrode plate.

[0088] (3) The amount per unit area of the composite material is small in the case where the electrode plate is manufactured from the composite material using the active material having the specific surface area of the first area and the tap density of the first density, as compared with the case where the electrode plate is manufactured from the composite material using the active material having the specific surface area of the first area and the tap density of the second density which is larger than the first density.

[0089] Even if the specific surface area of the active material used in the composite material is the same, if the tap density of the active material is different, the amount of increase in the specific surface area of the active material due to the pressing can have a deviation. The smaller the tap density of the active material used in the composite material, the more easily the thickness of the active material layer before the pressing increases. That is, the smaller the tap density of the active material used in the composite material, the more easily the displacement amount of the thickness of the active material layer due to the pressing increases. Therefore, the smaller the tap density of the active material used in the composite material, the more easily the amount of increase in the specific surface area of the active material due to the pressing increases.

[0090] According to the above method, the amount per unit area of the composite material is large in the case where the electrode plate is manufactured from the composite material using the active material having the large tap density, and the amount per unit area of the composite material is small in the case where the electrode plate is manufactured from the composite material using the active material having the small tap density. Therefore, the deviation in the first thickness is reduced in the case where the electrode plate is manufactured from the composite material using the active material having the first density, and in the case where the electrode plate is manufactured from the composite material using the active material having the second density. That is, the deviation in the amount of increase in the specific surface area of the active material due to the pressing is reduced in the case where the electrode plate is manufactured from the composite material using the active material having the first density, and in the case where the electrode plate is manufactured from the composite material using the active material having the second density. This reduces the deviation in the reaction area of the electrode plate.

[0091] (4) The amount per unit area of the composite material is smaller when the electrode plate is manufactured using the composite material that uses the active material having the second area of specific surface area and the first density of tap density than when the electrode plate is manufactured using the composite material that uses the active material having the second area of specific surface area and a second density of tap density that is larger than the first density.

[0092] Even if the active material used in the composite material has the same specific surface area, if the tap density of the active material is different, the increase in the specific surface area of the active material due to pressing can be different. The smaller the tap density of the active material used in the composite material, the more easily the thickness of the active material layer before pressing increases. That is, the smaller the tap density of the active material used in the composite material, the more easily the displacement of the thickness of the active material layer due to pressing increases. Therefore, the smaller the tap density of the active material used in the composite material, the more easily the increase in the specific surface area of the active material due to pressing increases.

[0093] According to the above method, the amount per unit area of the composite material is larger when the electrode plate is manufactured using the composite material that uses the active material having a large tap density, and the amount per unit area of the composite material is smaller when the electrode plate is manufactured using the composite material that uses the active material having a small tap density. Therefore, the deviation of the first thickness is reduced when the electrode plate is manufactured using the composite material that uses the active material having the first density of tap density and when the electrode plate is manufactured using the composite material that uses the active material having the second density of tap density. That is, the deviation of the increase in the specific surface area of the active material due to pressing is reduced when the electrode plate is manufactured using the composite material that uses the active material having the first density of tap density and when the electrode plate is manufactured using the composite material that uses the active material having the second density of tap density. This reduces the deviation of the reaction area of the electrode plate.

[0094] The above embodiment can be implemented by the following modifications. The above embodiment and the following modifications can be implemented in combination with each other within a range in which they are not technically contradictory.

[0095] • The electrode body 15 is not limited to the structure in which the positive electrode plate 16, the negative electrode plate 17, the separator 18, and the separator 19 are wound in overlap. For example, the electrode body 15 can also be a structure in which the positive electrode plate 16, the negative electrode plate 17, the separator 18, and the separator 19 are stacked in overlap without being wound in overlap.

[0096] • In the embodiment, the amount per unit area of the composite material is changed in four stages according to the physical properties of the active material, but is not limited thereto. The amount per unit area of the composite material can also be changed in two stages according to the physical properties of the active material, or in three stages. In addition, the amount per unit area of the composite material can also be changed in five or more stages.

[0097] • All features disclosed in the specification and / or claims are meant to be affixed to the inventor's application, independently of or in combination with each other, for the sole purpose of initially disclosing the invention for the patentability of the claims, and should not be understood as a limitation of the invention's scope as it is defined by the claims. With respect to any numerical limits recited in the disclosure, such limits are intended to include all values falling within the range, unless the context indicates otherwise.

Claims

1. A method of manufacturing a polar plate, which is a method of manufacturing a polar plate including a current collector and an active material layer, comprising: preparing a composite material by kneading an active material; forming the active material layer on the current collector by applying the composite material to the current collector; and pressing the active material layer to make the active material layer a prescribed thickness, adjusting an amount per unit area of the composite material applied to the current collector based on a specific surface area of the active material used in the composite material and a tap density of the active material used in the composite material, the amount per unit area of the composite material being smaller in a case where the polar plate is manufactured from the composite material using the active material having a specific surface area of a first area than in a case where the polar plate is manufactured from the composite material using the active material having a specific surface area of a second area smaller than the first area, the amount per unit area of the composite material being smaller in a case where the polar plate is manufactured from the composite material using the active material having a specific surface area of the first area and a tap density of a first density than in a case where the polar plate is manufactured from the composite material using the active material having a specific surface area of the first area and a tap density of a second density larger than the first density, and the amount per unit area of the composite material being smaller in a case where the polar plate is manufactured from the composite material using the active material having a specific surface area of the second area and a tap density of the first density than in a case where the polar plate is manufactured from the composite material using the active material having a specific surface area of the second area and a tap density of the second density larger than the first density.

3. A method of manufacturing a battery, which is a method of manufacturing a battery provided with a polar plate including a current collector and an active material layer, comprising: preparing a composite material by kneading an active material; forming the active material layer on the current collector by applying the composite material to the current collector; and pressing the active material layer to make the active material layer a prescribed thickness, adjusting an amount per unit area of the composite material applied to the current collector based on a specific surface area of the active material used in the composite material and a tap density of the active material used in the composite material, the amount per unit area of the composite material being smaller in a case where the polar plate is manufactured from the composite material using the active material having a specific surface area of a first area than in a case where the polar plate is manufactured from the composite material using the active material having a specific surface area of a second area smaller than the first area, the amount per unit area of the composite material being smaller in a case where the polar plate is manufactured from the composite material using the active material having a specific surface area of the first area and a tap density of a first density than in a case where the polar plate is manufactured from the composite material using the active material having a specific surface area of the first area and a tap density of a second density larger than the first density, and the amount per unit area of the composite material being smaller in a case where the polar plate is manufactured from the composite material using the active material having a specific surface area of the second area and a tap density of the first density than in a case where the polar plate is manufactured from the composite material using the active material having a specific surface area of the second area and a tap density of the second density larger than the first density. ​ ​ ​ ​ ​ ​ 2. The method of manufacturing a polar plate of claim 1, wherein, ​ ​ ​ ​ ​ ​ ​ ​ ​

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