Manufacturing method of electrode plate for secondary battery and coating device for electrode plate

Abstract

To fully utilize the three-dimensional structure of a porous current collector to create a secondary battery with large capacity and excellent input / output characteristics.SOLUTION: A coating device 1 for a lithium-ion secondary battery sprays and coats a positive electrode current collector 31, which is a porous current collector having a plate-like three-dimensional structure, with electrically charged paint particles from a nozzle 51 to form a positive electrode composite layer. A coating chamber 2 includes a reversing roller mechanism that reverses the positive electrode current collector 31 in a direction perpendicular to the discharge direction of the nozzle 51 and moves it back and forth multiple times to coat the positive electrode current collector 31 while reversing its front and back sides. The coating device 1 sprays the paint particles so as to penetrate the positive electrode current collector 31 in the thickness direction, thereby coating the positive electrode current collector 31.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an electrode plate for a secondary battery and a coating device for the electrode plate, and more particularly to a method for manufacturing an electrode plate for a secondary battery and a coating device for the electrode plate that form a suitable composite layer on a porous current collector. [Background technology]

[0002] Conventionally, for an electrode plate of a secondary battery, for example, a positive electrode plate 30 of a nonaqueous secondary battery such as a lithium-ion secondary battery 10 as shown in Figures 1 and 2, a slurry containing a positive electrode active material, a binder, a conductive additive, a solvent, etc. Then, as shown in Figure 18, such a slurry is applied in the form of a layer to a positive electrode current collector 31 made of Al foil to form a positive electrode plate 30 having a positive electrode composite layer 32.

[0003] To increase the capacity of such a secondary battery, it is conceivable to increase the thickness of the positive electrode composite layer 32 and increase the amount of positive electrode active material. On the other hand, to improve the input / output characteristics of the secondary battery, it is necessary to reduce the loss of kinetic energy when lithium ions move within the positive electrode by thinning the positive electrode composite layer 32. In this case, the amount of positive electrode active material will decrease. Thus, there is a trade-off between battery capacity and input / output characteristics.

[0004] Therefore, it has been proposed to use a porous current collector having a three-dimensional structure as the positive electrode current collector 31 as shown in Fig. 3. Specifically, by forming the positive electrode current collector 31 from a three-dimensional porous metal to increase its surface area and forming a positive electrode composite layer 32 on the skeleton 31a, it is possible to increase the battery capacity and improve the input / output characteristics even with a thin positive electrode plate 30.

[0005] In the electrode manufacturing method disclosed in Patent Document 1, first, a slurry for the electrode layer is applied to a substrate sheet, one side of a porous current collector is brought into contact with the substrate sheet, and the two sides are dried to form an integrated electrode layer, and then the substrate sheet is peeled off. This results in a porous current collector having an electrode layer on one side. Next, the slurry for the electrode layer is applied to the substrate sheet, and the non-electrode layer side of the porous current collector having an electrode layer on one side is brought into contact with the substrate sheet, and the two sides are dried to form an integrated electrode layer, and then the substrate sheet is peeled off. This results in a porous current collector having electrode layers on both sides. In this way, a smooth, thin electrode layer can be easily obtained on at least one side of the porous current collector, and an electrode plate with a uniform electrode surface can be obtained. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-41971 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the invention described in Patent Document 1, the electrode layer is formed only in a location close to the surface, which means that it is not possible to adequately control the thickness of the electrode layer all the way to the inside of the porous current collector having a three-dimensional structure, and it cannot be said that the structure of the porous current collector having a three-dimensional structure is fully utilized.

[0008] The problem that the method for manufacturing an electrode plate for a secondary battery and the coating device for an electrode plate of the present invention aim to solve is to fully utilize the structure of a porous current collector having a three-dimensional structure to produce an electrode plate for a secondary battery that has a large capacity and excellent input / output characteristics. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides a method for manufacturing an electrode plate for a secondary battery, which comprises spraying paint particles onto a porous current collector having a plate-like three-dimensional structure using a coating device to form a composite layer, and the paint particles contain an active material, and the paint particles have an average diameter D1 [μm] (d 50 ) average diameter D2 [μm] (d 50 ) and the coating device applies the coating material to the porous current collector by spraying the coating material particles so as to penetrate the porous current collector in the thickness direction.

[0010] The coating device may adjust the amount of the coating particles that adhere to the porous current collector by adjusting the amount of the coating particles that are discharged. The paint particles may be charged, and the porous current collector may be charged to a polarity different from that of the paint particles, so that the paint particles adhere to the porous current collector. In this case, the amount of the paint particles adhering to the porous current collector may be adjusted by adjusting the potential of the porous current collector.

[0011] The blower blows the paint particles onto the porous current collector at an air volume [m 3 The amount of the paint particles adhering to the porous current collector may be adjusted by adjusting either the air flow rate [m / s] or the wind speed [m / s].

[0012] The porous current collector may be housed in a long length and wound around a roller, and may be pulled out from the roller and coated with the paint particles in a coating chamber. The porous current collector may be rotated back and forth multiple times in the coating chamber in a direction perpendicular to the nozzle discharge direction, thereby coating both the front and back sides of the porous current collector.

[0013] After painting the porous current collector while turning it over, the paint particles are applied to the porous current collector with an average pore diameter D1 [μm] (d 50) average diameter D2 [μm] (d 50 ) and a second coating device can spray the paint particles onto the porous current collector in a manner that does not penetrate the porous current collector in the thickness direction, thereby applying the paint unevenly to only one side of the porous current collector.

[0014] In addition, the coating device for electrode plates of secondary batteries of the present invention is a coating device for electrode plates of secondary batteries that sprays and applies paint particles to a porous current collector having a plate-like three-dimensional structure using a coating device to form a composite layer, and is characterized in that the coating device sprays the paint particles so as to penetrate the porous current collector in the thickness direction, thereby applying paint to the porous current collector.

[0015] The coating device may adjust the amount of the coating particles that adhere to the porous current collector by adjusting the amount of the coating particles that are discharged. The present invention may further include a charging device that charges the paint particles and the porous current collector to a polarity different from that of the paint, thereby causing the paint particles to adhere to the porous current collector. In this case, the amount of the paint particles adhering to the porous current collector may be adjusted by adjusting the potential of the porous current collector.

[0016] A blower is provided to blow the paint particles onto the porous current collector, and the blower has an air volume [m 3 The amount of the paint particles adhering to the porous current collector may be adjusted by adjusting either the air flow rate [m / s] or the wind speed [m / s].

[0017] The coating chamber may include a reversing roller mechanism that reverses the porous current collector in a direction perpendicular to the discharge direction of the nozzle and reciprocates multiple times in the coating chamber to coat the porous current collector while reversing the front and back sides of the porous current collector.

[0018] After coating the porous current collector while turning it over, the average diameter D1 [μm] (d 50 ) average diameter D2 [μm] (d 50 The present invention may also include an uneven coating device that sprays the paint particles having a thickness of 1000 nm to 1500 nm using a second coating device so that the paint particles do not penetrate the thickness of the porous current collector, thereby coating the paint unevenly on only one side of the porous current collector.

[0019] The reversing roller mechanism may also include a positive pressure chamber that creates a positive pressure in the coating chamber to prevent the paint particles from leaking out of the coating chamber.

[0020] A recovery device may be provided on the downstream side of the coating chamber to recover the paint particles that have passed through the porous current collector. [Effects of the Invention]

[0021] According to the method for manufacturing an electrode plate for a secondary battery and the coating device for an electrode plate of the present invention, it is possible to fully utilize the structure of a porous current collector having a three-dimensional structure to produce an electrode plate for a secondary battery that has a large capacity and excellent input / output characteristics. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a perspective view showing the outline of the external configuration of a lithium ion secondary battery according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic diagram showing the configuration of a wound electrode body. [Figure 3] 1 is a micrograph showing an example of a porous current collector. [Figure 4] FIG. 2 is a schematic cross-sectional view showing an enlarged portion of the positive electrode plate of the present embodiment. [Figure 5] FIG. 2 is a schematic diagram showing the structure of a porous current collector. [Figure 6] FIG. 2 is a schematic diagram showing a coating device for a positive electrode plate of a lithium ion secondary battery according to the present embodiment. [Figure 7]1 is a flowchart showing the steps of a manufacturing process for a positive electrode plate of a lithium ion secondary battery. [Figure 8] 1 is a graph showing the relationship between the change in air volume [m / s] and the paint splash concentration in the depth direction and the paint deposition amount gradient in the thickness direction. [Figure 9] 10 is a graph showing the relationship between changes in air volume [m / s] and the linearity of ion paths. [Figure 10] 1 is a graph showing the relationship between the change in electrostatic voltage [V] and the paint adhesion rate and the paint adhesion amount gradient in the thickness direction. [Figure 11] 10 is a graph showing the relationship between changes in paint particle diameter / pore diameter and the paint scattering concentration in the depth direction and the coating amount gradient in the thickness direction. [Figure 12] FIG. 2 is a schematic diagram showing the state of adhesion of paint particles to a porous current collector on whose surface paint particles have first been sprayed. [Figure 13] FIG. 10 is a schematic diagram showing the state of adhesion of paint particles to a porous current collector that has been sprayed onto its back surface for the second time. [Figure 14] FIG. 10 is a schematic diagram showing the air flow after the second application. [Figure 15] FIG. 10 is a schematic diagram showing a coating device for an electrode plate of a secondary battery according to another embodiment. [Figure 16] 4 is a schematic diagram showing the state of paint particles adhering to a positive electrode current collector before the paint particles are sprayed onto the surface by a second coater. FIG. [Figure 17] 10 is a schematic diagram showing the state of adhesion of paint particles to a positive electrode current collector after the paint particles have been sprayed onto the surface by a second coater. FIG. [Figure 18] FIG. 1 is a schematic diagram showing the configuration of an electrode plate of a conventional secondary battery. DETAILED DESCRIPTION OF THE INVENTION

[0023] 1 to 15, a method for manufacturing an electrode plate for a secondary battery and a coating device for an electrode plate according to the present invention will be described using an embodiment of a method for manufacturing a positive electrode plate 30 for a lithium ion secondary battery 10 using a coating device 1 for the positive electrode plate 30 of a lithium ion secondary battery 10 as an example. Note that the present invention is not limited to this embodiment, and the type of battery is not limited, such as a non-aqueous electrolyte secondary battery, an alkaline storage battery, or an all-solid-state battery, and the positive electrode and negative electrode are also not limited.

[0024] <Background of this embodiment> The problem that the method for manufacturing the positive electrode plate 30 of the lithium-ion secondary battery 10 using the coating device 1 of this embodiment aims to solve is to fully utilize the structure of the porous current collector having a three-dimensional structure to produce a secondary battery with large capacity and excellent input / output characteristics.

[0025] The lithium ion secondary battery 10 shown in FIG. 1 and FIG. 2 is a battery in which lithium ions Li are transferred between a positive electrode plate 30 and a negative electrode plate 20 via a non-aqueous electrolyte solution 13. + For example, in the positive electrode plate 30, the positive electrode active material is a mixture of the non-aqueous electrolyte 13 and lithium ions Li + At the same time as exchanging the positive electrode current collector 31 and the electron e - The positive electrode active material must be fixed to the positive electrode current collector 31, so the positive electrode mixture layer 32 requires a binder with low conductivity. Here, the capacity of the positive electrode depends on the amount of positive electrode active material, so the more positive electrode active material there is, the greater the capacity. This increases the thickness of the positive electrode mixture layer 32, which increases the resistance value and also increases the distance between the positive electrode active material and the positive electrode current collector 31 and the nonaqueous electrolyte 13. As a result, there is a trade-off relationship in which input / output characteristics deteriorate. For this reason, in the past, a conductive additive was added, for example.

[0026] If the positive electrode current collector 31 shown in FIG. 3 is a porous current collector having a three-dimensional structure, the capacity [m 3 ] per surface area [m 2] is dramatically enlarged. By forming the positive electrode composite layer 32 on the skeleton 31a, even a thin positive electrode plate 30 can have a large capacity and improve input / output. Furthermore, the structure is such that the nonaqueous electrolyte 13 can easily penetrate into the interior. In this case, it is ideal to form the positive electrode composite layer 32 with a uniform thickness over the entire skeleton 31a of the positive electrode current collector 31.

[0027] However, in the method of transferring the positive electrode mixture layer 32 from the surface of the positive electrode plate 30 as in Patent Document 1, the positive electrode mixture layer 32 is formed unevenly on the surface of the positive electrode current collector 31. For this reason, it is not possible to form the positive electrode mixture layer 32 with an appropriate thickness inside the positive electrode current collector 31, which has a three-dimensional structure. In addition, the positive electrode mixture layer 32 formed on the surface of the positive electrode current collector 31 prevents the lithium ions Li of the nonaqueous electrolyte 13 inside the positive electrode current collector 31 from being transferred. + It becomes difficult to replace.

[0028] <Outline of the first embodiment> 6 is a schematic diagram showing a coating device 1 for a positive electrode plate 30 of a lithium-ion secondary battery 10 according to this embodiment. In the method for manufacturing a positive electrode plate 30 of a lithium-ion secondary battery 10 using the coating device 1 according to this embodiment, a positive electrode composite layer 32 is formed by spraying paint particles P onto a porous positive electrode current collector 31 having a plate-like three-dimensional structure using a nozzle 51 of a spray device 3.

[0029] The paint particles P contain a positive electrode active material and adhere to the positive electrode current collector 31 to form the positive electrode mixture layer 32. The paint particles P have an average diameter D1 [μm] (d 50 ) average diameter D2 [μm] (d 50 ) In the present application, the average diameter D1 [μm] (d 50 ) is determined by observation using an electron microscope. Unless otherwise specified, the "average particle size" is the median diameter (d 50) Then, in the coating chamber 2, the paint particles P are sprayed by the spraying device 3 so as to penetrate the positive electrode current collector 31 in the thickness direction. At this time, by using the principle of electrostatic coating, the paint is applied even to the skeleton 31a inside the positive electrode current collector 31, thereby forming the positive electrode composite layer 32. Note that because air is blown simultaneously with the spraying, the amount of paint that gets around and adheres to the back side of the sprayed surface is small, as is the case with normal electrostatic coating.

[0030] Therefore, in order to coat both sides uniformly, the positive electrode current collector 31 is reversed in the coating chamber 2 in a direction perpendicular to the discharge direction of the spray device 3 by the reversing roller mechanism 7, and the back of the positive electrode current collector 31 is coated.

[0031] Furthermore, the paint particles P sprayed onto the positive electrode current collector 31 penetrate the positive electrode current collector 31 in the thickness direction and flow downstream. The positive electrode current collector 31 is then turned over again by the reversing roller mechanism 7, and the front side thereof is again coated with the paint particles P flowing downstream. The positive electrode current collector 31 is then turned over again by the reversing roller mechanism 7, and the back side thereof is again coated. In this manner, the positive electrode current collector 31 is turned over multiple times by the reversing roller mechanism 7, and is coated from the front and back, and the positive electrode composite layer 32 is formed evenly all the way to the internal skeleton 31a.

[0032] In this embodiment, with such a configuration, positive electrode mixture layer 32 can be efficiently formed continuously and uniformly on skeleton 31a of long positive electrode current collector 31 having a three-dimensional structure. As a result, compared to conventional batteries equipped with foil-shaped current collectors, the thickness of the positive electrode current collector 31 can be increased if the positive electrode plate 30 is made of a porous current collector having a plate-shaped three-dimensional structure.

[0033] Therefore, the structure of the porous positive electrode current collector 31 having a three-dimensional structure can be fully utilized, and the positive electrode mixture layer 32 can be formed with a large surface area, so that a large capacity C [Ah] can be achieved by using a large amount of positive electrode active material. As a result, the energy density [Wh / m 3 ] can be made higher.

[0034] Furthermore, each positive electrode mixture layer 32 can be made thinner than before, and therefore the internal resistance [mΩ] can be reduced, resulting in a lithium ion secondary battery 10 with excellent input / output characteristics.

[0035] Furthermore, the porosity is maintained in the completed positive electrode plate 30, and the non-aqueous electrolyte 13 can be smoothly replaced. + By ensuring the movement of the signal, the input / output characteristics can be improved in this respect as well.

[0036] In the coating chamber 2, the static electricity voltage [V] can be adjusted by the charging device 6. The air blower 4 controls the amount of air passing through [m 3 / s] can be adjusted. Furthermore, by combining the average diameter D2 [μm] of the paint particles P and the number of repeated reverse coatings, it is possible to form an even and optimal ion path.

[0037] In addition, since the energy-intensive drying process is unnecessary or can be completed in a short time, CO2 emissions can be reduced and production costs can be kept down. In addition, its high thermal conductivity means that heat does not easily accumulate, and effective battery heat management can improve safety and extend battery life.

[0038] (Configuration of the first embodiment) A method for manufacturing the positive electrode plate 30 of the lithium ion secondary battery 10 using the coating device 1 of this embodiment will be described in detail below.

[0039] <Configuration of lithium-ion secondary battery 1> 1 is a perspective view showing the outline of the external configuration of a lithium ion secondary battery 10 of this embodiment. First, the configuration of an example of the lithium ion secondary battery 10 that is the premise of this embodiment will be briefly described.

[0040] The lithium-ion secondary battery 10 shown in FIG. 1 is a cell battery, and the cell batteries form a battery module 1M (not shown). The lithium-ion secondary battery 10, which is a cell battery, includes a plate-like rectangular battery case 11 with an opening on the upper side. An electrode assembly 12 is housed inside the battery case 11. A nonaqueous electrolyte 13 is filled into the battery case 11 through a liquid filling hole. The battery case 11 is made of a metal such as an aluminum alloy, and forms a battery container sealed by a lid. The lithium-ion secondary battery 10 also includes a positive electrode external terminal 14 and a negative electrode external terminal 15 used for charging and discharging power. The positive electrode external terminal 14 is electrically connected to a positive electrode current collector terminal 16 inside the battery case 11 via the lid. The negative electrode external terminal 15 is electrically connected to a negative electrode current collector terminal 17 inside the battery case 11 via the lid. The positive electrode current collector terminal 16 is electrically connected to a positive electrode current collector part 33 (see FIG. 2) of the electrode assembly 12. The negative electrode current collector terminal 17 is electrically connected to the negative electrode current collector portion 23 of the electrode body 12 (see FIG. 2).

[0041] <Electrode body 12> 2 is a schematic diagram showing the configuration of a wound electrode assembly 12. The electrode assembly 12 is formed by stacking a large number of negative electrode plates 20 and positive electrode plates 30 with separators 40 arranged between them. The stacked negative electrode plates 20, positive electrode plates 30, and separators 40 are wound to form a flat structure. The negative electrode plates 20 have a negative electrode composite layer 22 formed on a negative electrode current collector 21 made of copper foil as a base material. A negative electrode current collector 23 is provided at one end in a width direction W (winding axis direction) perpendicular to the winding direction (winding direction L). The negative electrode current collector 23 is configured so that the negative electrode composite layer 22 is not formed and the negative electrode current collector 21 is exposed.

[0042] The positive electrode plate 30 has a positive electrode current collector 31 having a skeleton 31a made of aluminum with a plate-like three-dimensional structure, on the surface of which a positive electrode composite layer 32 is formed. As shown in Fig. 2, a positive electrode current collector 33 is provided on the other end side (opposite to the negative electrode current collector 23) in a width direction W (winding axis direction) perpendicular to the winding direction (winding direction L) of the positive electrode current collector 31. The positive electrode composite layer 32 is not formed on the positive electrode current collector 33, and the metal of the positive electrode current collector 31 is exposed.

[0043] <Layer structure of electrode body 12> As shown in FIG. 2, the basic configuration of the electrode assembly 12 of the lithium ion secondary battery 10 includes a negative electrode plate 20, a positive electrode plate 30, and a separator 40.

[0044] The negative electrode plate 20 includes a negative electrode composite layer 22 on both sides of a negative electrode current collector 21 serving as a negative electrode substrate. One end of the negative electrode current collector 21 forms a negative electrode current collecting portion 23 where the metal is exposed. The positive electrode plate 30 includes a positive electrode composite layer 32 on both sides of a positive electrode current collector 31 serving as a positive electrode substrate. The other end of the positive electrode current collector 31 forms a positive electrode current collecting portion 33 where the metal is exposed.

[0045] The negative electrode plate 20 and the positive electrode plate 30 are stacked with a separator 40 interposed therebetween to form a laminate. As shown in Fig. 3, this laminate is wound in the longitudinal direction around the winding axis to form a wound electrode body 12 that is shaped into a flat shape as shown in Fig. 2.

[0046] <Nonaqueous electrolyte 13> The nonaqueous electrolyte 13 of the lithium-ion secondary battery 10 of this embodiment shown in FIG. 1 is impregnated in the electrode assembly 12. The nonaqueous electrolyte 13 is a composition in which a lithium salt is dissolved in an organic solvent. Examples of the lithium salt include LiClO4, LiPF6, LiAsF6, LiBF4, and LiSO3CF3. Examples of the organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and trifluoropropylene carbonate; chain carbonates such as diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, and dipropyl carbonate; ether compounds such as tetrahydrofuran, 2-methyltetrahydrofuran, and dimethoxyethane; sulfur compounds such as ethyl methyl sulfone and butane sultone; and phosphorus compounds such as triethyl phosphate and trioctyl phosphate. The nonaqueous electrolyte 13 may be composed of one or more of these compounds mixed together. However, the composition of the nonaqueous electrolyte 13 is not limited to this example.

[0047] <Components of the electrode body 12> Next, the negative electrode plate 20, the positive electrode plate 30, and the separator 40, which are components that make up the electrode assembly 12, will be described.

[0048] <Negative electrode plate 20> As shown in Fig. 4, negative electrode plate 20 is constructed by forming negative electrode composite layers 22 on both sides of negative electrode current collector 21, which is a negative electrode substrate. Negative electrode composite layer 22 is formed by applying a negative electrode composite paste to negative electrode current collector 21. Negative electrode plate 20 is then completed through a drying process, a pressing process, and a cutting process.

[0049] <Negative electrode current collector 21> In this embodiment, the negative electrode current collector 21 is made of Cu foil. The negative electrode current collector 21 serves as a base for the aggregate of the negative electrode mixture layer 22, and also functions as a current collecting member that collects electricity from the negative electrode mixture layer 22. One end of the negative electrode current collector 21 serves as a negative electrode current collecting part 23 where the negative electrode mixture layer 22 is not formed and the metal surface is exposed. In other words, the negative electrode active material particles are electrically connected to the negative electrode external terminal 15 via the negative electrode current collector 21, the negative electrode current collecting part 23, and the negative electrode current collecting terminal 17.

[0050] <Negative electrode composite layer 22> In this embodiment, the negative electrode active material is a powdered carbon material made of graphite or the like having a layered structure, and lithium ions Li + It is a material that can absorb and release energy.

[0051] <Positive electrode plate 30> Fig. 4 is an enlarged cross-sectional view of a portion of positive electrode plate 30 of this embodiment. As shown in Fig. 3, positive electrode plate 30 is formed into a plate shape by spreading skeleton 31a of porous positive electrode current collector 31 having a three-dimensional structure throughout the entire plate. As shown in Fig. 4, a positive electrode composite layer 32 is formed with a uniform thickness on the surface of skeleton 31a. This positive electrode composite layer 32 is formed by coating using spray device 3 of coating device 1. Thereafter, positive electrode plate 30 is completed through a drying process, a shaping press process, and a cutting process.

[0052] <Positive electrode current collector 31> In this embodiment, the positive electrode current collector 31 is a porous current collector made of a porous metal having a three-dimensional structure made of Al. The positive electrode current collector 31 serves as a base for the aggregate of the positive electrode mixture layer 32 and also functions as a current collecting member that collects electricity from the positive electrode mixture layer 32.

[0053] A specific example of a porous current collector having a three-dimensional structure is Celmet (registered trademark) from Sumitomo Electric Industries, Ltd. Celmet is a porous metal body whose skeleton has a three-dimensional network structure.

[0054] It has a large porosity (void ratio) of up to 98%, and each pore is a continuous air hole, allowing sprayed paint particles P to easily pass through in the thickness direction. In addition, the average diameter of the pores D1 [μm] (d 50 ) is between 15 and 100 [μm], and the average diameter D2 [μm] (d 50 ) of 1 to 20 [μm]. Therefore, the coating particles P are formed so that the average diameter D1 [μm] (d 50 ) average diameter D2 [μm] (d 50 ), which allows the paint particles P to easily pass through the plate-shaped positive electrode current collector 31. As the coating progresses, the positive electrode mixture layer 32 that is formed reduces the initial pore average diameter D1 [μm] (d 50 ) is small, so this point is also taken into consideration when calculating.

[0055] In addition, the specific surface area [m 2 / m 3 ] is a value exceeding 10 to 60, which is an extremely large value compared to conventional Al foils. Therefore, the interface between positive electrode mixture layer 32 formed here and nonaqueous electrolyte solution 13 can be made large.

[0056] Furthermore, compared to a porous body made of sintered metal powder or metal fiber, it is more flexible (elastic), and the long positive electrode current collector 31 before processing can be wound around the supply roller 8a and accommodated, and then supplied.

[0057] Although Al is exemplified as the positive electrode substrate constituting the positive electrode current collector 31, it may be made of, for example, a conductive material made of a metal with good conductivity. Examples of the material with good conductivity that can be used include Al and materials containing Al alloys. Furthermore, the configuration of the positive electrode current collector 31 is not limited to this.

[0058] Furthermore, porous bodies made by sintering metal powder or metal fibers are not excluded, and metal porous bodies with a three-dimensional mesh structure made by sintering metal powder or metal fibers manufactured by Kodan Metals Co., Ltd. can also be used.

[0059] <Positive electrode composite layer 32> Positive electrode mixture layer 32 is formed by applying paint particles P to skeleton 31a of positive electrode current collector 31. The composition of paint particles P includes, in addition to positive electrode active material particles that form positive electrode mixture layer 32, a binder (binding material), various additives, and an organic solvent as a solvent.

[0060] In this embodiment, the paint particles P are charged in the same manner as in electrostatic coating and then attached to the positive electrode current collector 31. For this reason, the amount of organic solvent can be reduced compared to conventional positive electrode composite slurries, or it can be omitted altogether. Therefore, the drying step after attachment can be shortened or omitted.

[0061] In addition, the thickness of the conventional layered positive electrode mixture layer 32 is large. Therefore, graphite such as AB (acetylene black), CNC (carbon nanotube), or CF (carbon fiber) has been added as a conductive additive for the purpose of forming a conductive network in the positive electrode mixture layer 32. In this embodiment, the thickness D3 [μm] (d 50 ) is relatively thin, so the addition of a conductive additive is omitted. Of course, a conductive additive may be added as appropriate.

[0062] <Composition of positive electrode active material> The positive electrode active material particles contain a lithium transition metal oxide having a layered crystal structure. The lithium transition metal oxide contains one or more predetermined transition metal elements in addition to Li. The transition metal element contained in the lithium transition metal oxide is preferably at least one of Ni, Co, and Mn. The positive electrode active material of this embodiment is exemplified by a ternary system known as NCM, which contains lithium transition metal oxides containing all of Ni, Co, and Mn.

[0063] The positive electrode active material of this embodiment is not limited to a lithium transition metal oxide containing all of Ni, Co, and Mn. It may also contain, for example, Al. The positive electrode active material may also be LiMnO4, LiFePO4, or the like.

[0064] <Separator 40> The separator 40 is a highly insulating nonwoven fabric made of a porous resin such as polypropylene, which holds the nonaqueous electrolyte solution 13 between the negative electrode plate 20 and the positive electrode plate 30. Alternatively, the separator 40 may be a porous polymer membrane such as a porous polyethylene membrane, a porous polyolefin membrane, or a porous polyvinyl chloride membrane, or a lithium ion or ion conductive polymer electrolyte membrane, either singly or in combination.

[0065] <Coating device 1 for positive electrode plate 30 of lithium ion secondary battery 10> FIG. 6 is a schematic diagram showing the configuration of a coating device 1 for a positive electrode plate 30 of a lithium-ion secondary battery 10 according to this embodiment. Next, the coating device 1 for a positive electrode plate 30 of a lithium-ion secondary battery 10 will be described. The manufacturing apparatus for the positive electrode plate 30 of the lithium-ion secondary battery 10 according to this embodiment includes, in addition to the coating device 1, a dryer (not shown) for drying the positive electrode plate 30 after coating with the positive electrode composite layer 32, a press (not shown) for shaping the positive electrode plate 30, and a cutter (not shown) for cutting the positive electrode plate 30 to a predetermined length. However, since well-known configurations can be used, these components are not shown and will not be described in detail. Here, the configuration of the coating device 1 according to this embodiment will be described in detail with reference to FIG. 6. The coating device 1 includes a coating chamber 2, a spraying device 3, a blower 4, a charging device 6, a reversing roller mechanism 7, a supply roller 8a, a positive electrode plate winding roller 8b, a paint particle recovery device 9, and the like. Each of these components will be described in detail below.

[0066] <Painting chamber 2> The coating device 1 for the positive electrode plate 30 of the lithium-ion secondary battery 10 of this embodiment has a main body 2a of a cylindrical coating chamber 2 that has a rectangular cross section and extends horizontally. A blower 4 is attached to the upstream end of the main body 2a (the right side in FIG. 8). A paint particle recovery device 9 is attached to the downstream end of the main body 2a (the left side in FIG. 8). The main body 2a, the blower 4, and the paint particle recovery device 9 form an enclosed coating space.

[0067] At the position where the reversing roller mechanism 7 is located in the main body 2a of the coating chamber 2, a space formed by a positive pressure chamber 2b is formed outside the main body 2a to cover the reversing roller mechanism 7. This positive pressure chamber 2b is maintained at a higher air pressure than the internal pressure of the main body 2a of the coating chamber 2 by a pressurizing device 2c. In other words, it is at a positive pressure relative to the pressure in the main body 2a of the coating chamber 2. The positive electrode current collector 31 guided into the main body 2a by the reversing roller mechanism 7 is guided into the main body 2a through a slit provided in the main body 2a. By maintaining a positive pressure inside the positive pressure chamber 2b relative to the main body 2a, the discharge of paint particles P from the main body 2a of the coating chamber 2 to the outside is suppressed.

[0068] <Spraying device 3> The spraying device 3 is composed of a paint supply device 5 and a plurality of nozzles 51 arranged inside the upstream end of the main body 2a. In this embodiment, the nozzles 51 are composed of electrostatic spray guns, and paint is supplied from the paint supply device 5 under pressure. In this embodiment, an example is the EP-MG10 powder nozzle manufactured by Anest Iwata Corporation. The supplied paint is atomized from the nozzles 51 and sprayed as paint particles P. The discharge rate [g / s] of the paint sprayed from the nozzles 51 can be adjusted by adjusting the pressure of the paint delivered from the paint supply device 5.

[0069] <Blower 4> The blower 4 introduces outside air from the upstream side and blows it downstream using a fan (not shown). The paint particles P ejected from the nozzle 51 are blown downstream by the air blown from the blower 4. The paint particles P pass through the holes 31b of the positive electrode current collector 31 by the air blown by the blower 4. The blower 4 blows air at a rate of at least [m 3 / s], wind speed [m / s], or both can be adjusted. 3 / s] and the wind speed [m / s], the amount of paint particles P adhering to the positive electrode current collector 31 can be adjusted by adjusting the amount M [g / m 2 ] can be adjusted.

[0070] <Charging device 6> The charging device 6 is equipped with a high-voltage generator and generates positive ions at the tip of the nozzle 51 via a power cable. This positively charges the paint particles P sprayed from the electrostatic spray gun. It also generates negative ions, which negatively charge the positive electrode collector 31 that transports the paint particles within the coating chamber 2. A high voltage of -30 kV to -90 kV is supplied to the paint particles P. In this embodiment, the voltage is applied to the paint particles P via the nozzle 51. Alternatively, an independent ionizer may be used to irradiate negative ions toward the paint particles P.

[0071] Additionally, the positive electrode current collector 31, which is the object to be coated, is kept grounded (positive). In practice, it is charged via the reverse rollers 7a-7h. By applying a high voltage in this manner, an electrostatic field is formed between the negatively charged paint particles P and the positive electrode current collector 31. The paint particles P atomized from the nozzle 51 are negatively charged, enter the electrostatic field, and adhere to the positive electrode current collector 31. Because the electrostatic field extends to the back surface of the positive electrode current collector 31, the paint particles P can be applied to the back surface of the positive electrode current collector 31. However, in this embodiment, because the air blower 4 creates an air flow that passes through the positive electrode current collector 31 within the coating chamber 2, more paint particles P adhere to the upstream side, and less to the downstream side (back side). For this reason, coating is performed from both the front and back.

[0072] <Supply roller 8a, reversing roller mechanism 7, positive electrode plate take-up roller 8b> The long positive electrode current collector 31, which is formed as a porous current collector having a plate-like three-dimensional structure made of Al, is elastic and is arranged on the upstream outside of the coating chamber 2 while being wrapped around the supply roller 8a and housed therein.

[0073] The positive electrode current collector 31 drawn from the supply roller 8a is drawn into the main body 2a through a slot provided in the positive pressure chamber 2b and the main body 2a, maintaining a small gap. It is then turned over by a reversing roller 7a arranged in the positive pressure chamber 2b, passing through a slit on the opposing surface of the main body 2a so as to traverse the main body 2a. The turned-over positive electrode current collector 31 is then drawn back into the main body 2a through a slot provided in the main body 2a. It is then turned over again by a reversing roller 7b arranged in the positive pressure chamber 2b, passing through a slit on the opposing surface of the main body 2a so as to traverse the main body 2a.

[0074] This operation is performed by reversing rollers 7c to 7g, and positive electrode current collector 31, which has been turned over, travels back and forth four times across main body 2a. During this time, positive electrode composite layer 32 is formed on positive electrode current collector 31, becoming positive electrode plate 30. In this manner, in this embodiment, positive electrode composite layer 32 can be continuously formed on long positive electrode current collector 31.

[0075] As described above, some of the reverse rollers 7a to 7h are grounded by the charging device 6 and charged as positive electrodes. The coated positive electrode plate 30 is guided by the reversing roller 7h and drawn out of the body 2a through the positive pressure chamber 2b and a slot provided in the body 2a, maintaining a small gap between them. The drawn positive electrode plate 30 is then wound up around the positive electrode plate winding roller 8b and stored.

[0076] <Paint particle recovery device 9> The paint particle recovery device 9 is airtightly connected to the main body 2a of the coating chamber 2 on the downstream side thereof, and a vent port (not shown) is connected to the downstream end thereof, which discharges air from the coating chamber 2 to the outside. The paint particle recovery device 9 recovers paint particles P passing through the coating chamber 2 along with the air. The paint particle recovery device 9 may be of a tank type, centrifugal type, filter type, or the like. In this embodiment, the EP-MG10 manufactured by Anest Iwata Corporation may be used, for example. The paint particles P separated from the air are liquefied, recovered through a recovery port 9b, and recycled as paint particles P. Meanwhile, the air from which the paint particles P have been removed is exhausted through an exhaust port 9a.

[0077] <Manufacturing Process of Positive Electrode Plate 30 of Lithium-ion Secondary Battery 10> 7 is a flowchart showing the steps of the manufacturing process for the positive electrode plate 30 of the lithium ion secondary battery 10. The manufacturing process for the positive electrode plate 30 of the lithium ion secondary battery 10 of this embodiment includes the following steps: a positive electrode current collector manufacturing step (S1), a coating step (S2), a drying step (S3), a shaping and pressing step (S4), and a shaping and cutting step (S5).

[0078] In the positive electrode current collector manufacturing step (S1), in this embodiment, a long, plate-like porous current collector having a three-dimensional structure is purchased to form the positive electrode current collector 31. Details of the manufacturing method thereof are omitted.

[0079] Next, in the coating step (S2), coating particles P are applied to the positive electrode current collector 31, which will be described in detail later. After the positive electrode composite layer 32 is formed, a drying step (S3) is performed. For example, the positive electrode composite layer 32 is dried for 180 minutes using hot air at a temperature of 150°C. After that, a shaping press step (S4) is performed to improve the dimensional accuracy in the thickness direction and to improve the smoothness of the surface. Then, in the shaping and cutting step (S5), the positive electrode plate 30 is completed by cutting to the length required for each cell battery.

[0080] <Coating process (S2)> In the coating process (S2), as shown in FIG. 6, the long positive electrode current collector 31 is pulled out from the supply roller 8a and placed on reversing rollers 7a-7h. The nozzle 51 then makes four reciprocating movements within the main body of the coating chamber 2, reversing the movement in a direction perpendicular to the direction in which the paint particles P are discharged. The positive electrode current collector 31 is then wound up by the positive electrode plate take-up roller 8b. Therefore, the positive electrode current collector 31 faces the nozzle 51 in the order front-back-front-back-front-back-front-back. These respective sides are referred to as the first side S1 to the eighth side S8. Next, the positive electrode current collector 31 is transported at a constant speed so as to be wound up by the positive electrode plate take-up roller 8b. Air is also blown by the air blower 4. The charging device 6 applies a voltage to the nozzle 51, and the paint supply device 5 pressure-feeds the paint to the nozzle 51 at a predetermined pressure. Negatively charged paint particles P are then sprayed from the nozzle 51 onto the transported positive electrode current collector 31.

[0081] <Preliminary processing> In this embodiment, the positive electrode current collector 31 may be pretreated in advance. For example, it may be degreased, washed with water, and treated with trivalent chromium acid. Aluminum conversion coating is a technique that deposits a highly effective anti-rust coating on aluminum through a chemical reaction. This conversion coating has high corrosion resistance and is applied as a paint base to improve paint film adhesion and corrosion resistance. Dust removal treatment is also performed.

[0082] <Painting of the first surface S1> FIG. 12 is a schematic diagram showing the state of paint particle adhesion on a porous current collector after the paint particles have been first sprayed onto the surface. The paint particles P sprayed from the nozzle 51 are carried by the airflow from the air blower 4 and first reach the first surface S1 of the positive current collector 31, which is wound between the supply roller 8a and the reverse roller 7a. As a result, the negatively charged paint particles P on the positive current collector 31 shown in FIG. 5 adhere to the upstream side of the first surface S1, forming a positive composite layer 32, as shown in FIG. 12. In typical electrostatic coating, the paint particles P also adhere to the second surface S2 on the rear side. However, in this embodiment, the air blown by the air blower 4 passes through the pores 31b of the porous positive current collector 31, so almost no paint particles P adhere to the downstream second surface S2 on the rear side.

[0083] <Painting of the second surface S2> FIG. 13 is a schematic diagram showing the state of paint particles adhering to a porous current collector after the second coating of the back surface by spraying paint particles. The positive current collector 31, with the thin positive electrode composite layer 32 formed on its first surface S1, is conveyed and reversed by the reverse roller 7a, and guided to a position where the second surface S2 on the back side faces the upstream nozzle 51. As shown in FIG. 13, paint particles P passing through the holes 31b of the positive current collector 31 reach the second surface S2 of the positive current collector 31, which is rotated between the reverse rollers 7a and 7b. Then, the paint particles P adhere to the upstream side of the second surface S2, which is the surface opposite to the positive electrode composite layer 32 formed on the first surface S1 of the positive current collector 31 shown in FIG. 12, thereby forming the positive electrode composite layer 32. At this stage, thin positive electrode composite layers 32 of the same thickness are formed on both the front and back surfaces of the positive current collector 31.

[0084] <Painting of the 3rd surface S3 to the 8th surface S8> This operation is repeated by reversing rollers 7c to 7h, and positive electrode composite layer 32 is formed on the front and back surfaces of positive electrode current collector 31. As a result, positive electrode composite layer 32 gradually becomes thicker with the thickness of the front and back surfaces balanced. Then, when positive electrode composite layer 32 is overlaid on eighth surface S8, positive electrode plate 30 having positive electrode composite layer 32 of a specified thickness on both surfaces is completed.

[0085] 14 is a schematic diagram showing the air flow after the second coating on the second surface S2. As shown in FIG. 14, the pores 31b are maintained on the eighth surface S8 of the completed positive electrode plate 30, and the air A containing the paint particles P passes through the pores 31b and flows downstream in the coating chamber 2. These operations can also be performed continuously, and the long positive electrode current collector 31 can be continuously formed with the positive electrode composite layer 32 to form the completed positive electrode plate 30.

[0086] <Paint recovery> The air containing paint particles P flowing downstream of the coating chamber 2 reaches the paint particle recovery device 9. The paint particle recovery device 9 separates the air containing paint particles P that has reached it into paint and air using an air-water separator provided in the paint particle recovery device 9. The paint particles P separated from the air are liquefied and recovered from the recovery port 9b, and recycled again as paint particles P. Meanwhile, the air from which the paint particles P have been removed is exhausted from the exhaust port 9a.

[0087] <Adjusting the Thickness of Positive Electrode Composite Layer 32> Figure 8 shows the air volume [m 3 / s] and the relationship between the paint splash concentration in the depth direction and the paint deposition amount gradient in the thickness direction. 3 / s] and the paint splash concentration in the depth direction. 3 / s] and the thickness direction deposition amount gradient. 3 / s] increases, the paint particles P fly farther, and the paint scattering concentration in the depth direction (the concentration of paint particles P at a specified position downstream) increases. On the other hand, as shown in G2, 3 / s] increases, the thickness direction adhesion amount gradient decreases. That is, this is because the number of paint particles P passing through the pores 31b of the positive electrode current collector 31 increases. Therefore, the air volume [m 3 / s] is required. On the other hand, too large an air volume [m 3 / s], the number of paint particles P passing through the holes 31b of the positive electrode current collector 31 becomes too large. From this point of view, the air volume [m 3 / s] needs to be adjusted.

[0088] Figure 9 shows the air volume [m 3 / s] and the linearity of the ion path. 3 / s] and the linearity of the ion path. 3 When the airflow rate [m / s] is large, the linearity of the ion path is excellent. That is, in the completed positive electrode plate 30, sufficiently linear pores 31b are formed, and the nonaqueous electrolyte 13 can easily flow. From this point of view, a sufficient airflow rate [m 3 / s] is desirable.

[0089] FIG. 10 is a graph showing the relationship between changes in electrostatic voltage [V] and the paint adhesion rate and thickness-wise adhesion gradient. G4, which slopes upward to the right, is a graph showing the relationship between changes in electrostatic voltage [V] and the paint adhesion rate. If the paint particles P are sufficiently charged, the adhesion rate to the positive electrode current collector 31 increases. G5, which slopes downward to the right, is a graph showing the relationship between changes in electrostatic voltage [V] and the thickness-wise adhesion gradient. When the electrostatic voltage [V] is high, the static adsorption force becomes stronger, and the paint particles P adhere sufficiently not only to the first surface S1 but also to the eighth surface S8, so the thickness-wise adhesion gradient becomes smaller.

[0090] FIG. 11 is a graph showing the relationship between the change in the average diameter D2 of the paint particles P / the average diameter D1 of the pores 31b, and the paint scattering concentration in the depth direction and the gradient of the paint deposition amount in the thickness direction. G6, which slopes upward to the right, is a graph showing the relationship between the change in the average diameter D2 of the paint particles P / the average diameter D1 of the voids 31b and the paint scattering concentration in the depth direction. The larger the ratio D2 / D1, the easier it is for the paint particles P to pass through the voids 31b, and the paint particles P are scattered farther by the blower 4. This results in a higher paint scattering concentration in the depth direction.

[0091] Graph G7, which slopes downward to the right, is a graph showing the relationship between the change in the average diameter D2 of the paint particles P / the average diameter D1 of the voids 31b and the gradient of the amount of adhesion in the thickness direction. The larger the ratio D2 / D1, the easier it is for the paint particles P to pass through the voids 31b, and the paint particles P are blown farther by the blower 4. As a result, the paint particles P adhere sufficiently not only to the first surface S1 but also to the eighth surface S8, and the gradient of the amount of adhesion in the thickness direction becomes smaller.

[0092] As explained above, the air volume [m 3 / s], static electricity voltage [V], and the ratio of average diameter D2 of paint particles P to average diameter D1 of pores 31b can be optimized to control the thickness of positive electrode composite layer 32. 3 / s] can also be controlled as wind speed [m / s].

[0093] In addition, the pressure [Pa] and the amount of paint sent from the paint supply device 5 [m 3 / s], the discharge rate [m 3 You can also change the [ / s]. The viscosity may also be adjusted by adjusting the composition of the paint or the amount of solvent.

[0094] Of course, it goes without saying that the positive electrode active material contained in the paint and the diameter of the pores 31b of the positive electrode current collector 31 can be selected. As described above, in this embodiment, an appropriate positive electrode mixture layer 32 can be formed by various factors.

[0095] (Operation of the first embodiment) In the lithium-ion secondary battery 10 of this embodiment, coating particles P are sprayed onto a positive electrode current collector 31, which is a porous current collector having a plate-like three-dimensional structure, using a coating device 1 to form a positive electrode composite layer 32. The coating particles P contain a positive electrode active material, and the average diameter D1 [μm] (d 50 ) average diameter D2 [μm] (d 50) is included. Coating device 1 applies paint particles P by spraying them so as to penetrate through the thickness of positive electrode current collector 31. The paint particles P are negatively charged and positive electrode current collector 31 is positively charged, causing the paint particles P to adhere to positive electrode current collector 31. Within coating chamber 2, positive electrode current collector 31 is rotated back and forth multiple times in a direction perpendicular to the discharge direction of nozzle 51, coating the front and back of positive electrode current collector 31 and forming positive electrode composite layer 32. For this purpose, positive electrode composite layer 32 is formed to a uniform thickness on skeleton 31a that constitutes positive electrode current collector 31.

[0096] (Effects of the first embodiment) (1-1) The manufacturing method of the positive electrode plate 30 of the lithium ion secondary battery 10 and the coating device 1 for the positive electrode plate 30 of the present embodiment have the effect of making it possible to fully utilize the structure of the porous current collector having a three-dimensional structure, thereby producing a lithium ion secondary battery 10 with large capacity and excellent input / output characteristics.

[0097] (1-2) The coating device 1 sprays and applies the paint particles P onto the positive electrode current collector 31, which is a porous current collector having a plate-like three-dimensional structure, to form the positive electrode composite layer 32. This has the effect of making use of a larger surface area to form the positive electrode composite layer 32.

[0098] (1-3) The coating particles P contain a positive electrode active material, and the coating particles P have an average diameter D1 [μm] (d 50 ) average diameter D2 [μm] (d 50 ). The coating device 1 then sprays the coating particles P so as to penetrate the positive electrode current collector 31 in the thickness direction, thereby coating the positive electrode current collector 31. This has the effect of effectively coating the inside of the pores 31b. Furthermore, by utilizing the coating particles P that have passed downstream, coating can also be performed downstream.

[0099] (1-4) The coating device 1 discharges the paint particles P at a rate [m 3 / s], the amount of paint particles P adhering to the positive electrode current collector 31 [g / m 2This has the effect of enabling an appropriate positive electrode mixture layer 32 to be formed.

[0100] (1-5) The paint particles P are negatively charged, and the positive electrode current collector 31 is positively charged, different from the paint particles P, so that the paint particles P adhere to the positive electrode current collector 31 in an electrostatic field. This has the effect of making it possible to more reliably cause the paint particles P to adhere to the positive electrode current collector 31 by the force of static electricity.

[0101] (1-6) In this case, by adjusting the difference in relative potential [V] between the paint particles P and the positive electrode current collector 31, the adhesion amount [g / m 2 ] can be adjusted.

[0102] (1-7) The blower 4 blows the paint particles P onto the positive electrode current collector 31 at an air volume [m 3 / s] or wind speed [m / s], the amount of paint particles P adhering to the positive electrode current collector 31 can be controlled. 2 ] can be adjusted.

[0103] (1-8) The positive electrode current collector 31 is wound around the supply roller 8a in a long length and accommodated therein, and is then pulled out from the supply roller 8a and coated with the paint particles P in the coating chamber 2. This has the effect of enabling the positive electrode plates 30 to be produced continuously and efficiently.

[0104] (1-9) In the coating chamber 2, the positive electrode current collector 31 is inverted in a direction perpendicular to the discharge direction and reciprocated multiple times to coat the front and back of the positive electrode porous current collector. This has the effect of allowing the positive electrode composite layer 32 to be formed uniformly and in a balanced manner on the front and back of the positive electrode current collector 31.

[0105] (1-10) A reversing roller mechanism 7 is provided that reversing the positive electrode current collector 31 in a direction perpendicular to the discharge direction within the coating chamber 2 and reciprocating multiple times, and coating the conveyed positive electrode current collector 31 while reversing its front and back. This has the effect of automatically reversing the positive electrode current collector 31, thereby enabling continuous production of positive electrode plates 30.

[0106] (1-11) The reversing roller mechanism 7 is provided with a positive pressure chamber 2b that creates a positive pressure in the coating chamber 2 so that paint particles P do not leak out of the coating chamber 2. This has the effect of preventing paint particles P from leaking out of the coating chamber 2.

[0107] (1-12) A recovery device is provided to recover the paint particles P that have passed through the positive electrode current collector 31 on the downstream side of the coating chamber 2. This has the effect of reducing paint waste and purifying the exhaust air.

[0108] (Second embodiment) 15 is a schematic diagram showing a second coater 101 for the positive electrode plate 30 of the lithium-ion secondary battery 10 according to the second embodiment. The method for manufacturing the positive electrode plate 30 of the lithium-ion secondary battery 10 and the coater 101 for the positive electrode plate 30 according to the second embodiment are characterized in that they include a second coater 101 in addition to the coater 1 of the first embodiment. The second coater 101 is an uneven coater that forms a positive electrode composite layer 32 on only one side of the positive electrode plate 30, the front and back of which have been uniformly coated by the coater 1.

[0109] The second coating device 101 includes a coating chamber 102, a spraying device 103, a blower device 104, a paint supply device 105, a nozzle 151, a charging device 106, and a paint particle recovery device 109, similar to those of the coating device 1. Therefore, detailed description of these components will be omitted.

[0110] On the other hand, the second coating device 101 does not have a reverse roller mechanism 7, nor does it have a positive pressure chamber 2b associated therewith. In addition, a different paint is used than the paint used in the coating device 1. That is, the coating device 101 applies paint particles P having an average diameter D2 [μm] of 80 [%] or more of the average diameter D1 [μm] of the pores 31b of the positive electrode current collector 31. L It is set to be.

[0111] 16 is a schematic diagram showing the state of the paint particles P attached to the positive electrode current collector 31 before the paint particles P are sprayed onto the surface by the second coater 101. That is, this is the state after the paint particles P have been applied by the first coater 1.

[0112] FIG. 17 shows a coating of paint particles P on a surface by a second coating device 101. L 17 is a schematic diagram showing the state of adhesion of paint particles P to a positive electrode current collector 31 after the paint particles P are sprayed and applied. L The average diameter D2 [μm] of the pores 31b is 80 [%] or more of the average diameter D1 [μm] of the pores 31b, and the average diameter D2 [μm] is larger than the average diameter D1 [μm] of the pores 31b. L Therefore, the paint particles P L enters the pores 31b, but most of it remains within the pores 31b. Therefore, by further utilizing the space of the pores 31b, the amount of positive electrode active material in the positive electrode plate 30 can be increased, and the energy density [Wh / m 3 ] can be increased. In addition, the paint particles P L does not block the pores 31b, and the lithium ions Li in the nonaqueous electrolyte solution 13 + The movement is easily done.

[0113] (Effects of the second embodiment) (2-1) Compared to the first embodiment, the amount of positive electrode active material in the positive electrode plate 30 is increased by further utilizing the space of the pores 31b, thereby increasing the capacity C [Wh] and achieving a higher energy density [Wh / m 3 ] can be improved.

[0114] (Another example) The description of the present embodiment is merely an example of the present invention and is not intended to limit the present invention. The present invention can be implemented as in the following alternative examples, and in these alternative examples, the invention can be optimized by those skilled in the art.

[0115] In the embodiment, the positive electrode plate 30 of the lithium ion secondary battery 10 has been described as an example. However, the electrode plate is not limited to the positive electrode plate 30, and the negative electrode plate 20 may also be used.

[0116] The secondary battery is not limited to the lithium ion secondary battery 10, but may be other non-aqueous electrolyte secondary batteries, alkaline secondary batteries, or other secondary batteries.

[0117] In this embodiment, the positive electrode current collector 31 is made of Celmet (registered trademark) manufactured by Sumitomo Electric Industries, Ltd., but needless to say, the present invention is not limited to this. Any porous current collector having a plate-like three-dimensional structure can be used, and for example, a porous current collector having a plate-like three-dimensional structure made of inflexible sintered material or ceramics may be used. In this case, the positive electrode plate 30 is formed using a material that has been cut into a flat plate shape in advance, without using a supply roller 8a or the like.

[0118] The drawings are schematic diagrams for explaining the configuration of the positive electrode plate 30 used in the lithium ion secondary battery 10 of this embodiment, and the number, shape, dimensions, etc. thereof do not reflect the actual form.

[0119] The numerical values and numerical ranges of quantities, shapes, dimensions, shapes, materials, etc. are merely examples and do not limit the present invention. Needless to say, they may be optimized as appropriate by those skilled in the art. The flowchart in FIG. 7 is an example of a method for manufacturing the positive electrode plate 30 used in the lithium ion secondary battery 10, and is not limited to this, and the order can be changed, and steps can be added or deleted.

[0120] In addition, it goes without saying that the present invention can be implemented by those skilled in the art by adding, deleting, or modifying its configuration, provided that the changes do not deviate from the scope of the claims. [Explanation of symbols]

[0121] A...Air C[Ah]…(Battery) capacity D1 [μm] (d 50 )...(pore) average diameter D2 [μm] (d 50 )...(paint particle) average diameter D3 [μm] (d 50 )…(Positive electrode composite layer) Thickness Q [g / s]...(paint particle) discharge rate F[m 3 / s]…Air volume V[m / s]…Wind speed P…Paint particles M [g / m 2 ]...(paint particle) adhesion amount E [V]...(electrostatic field) electric potential S1~S8…Side 1~Side 8 G1…Air volume [m 3 10 is a graph showing the relationship between the change in the paint ejection rate [ppm / s] and the paint ejection concentration in the depth direction.

[0122] G2…air volume [m 3 1 is a graph showing the relationship between the change in the adhesion amount [g / s] and the thickness direction adhesion amount gradient. G3…Air volume [m 3 10 is a graph showing the relationship between the change in [times] / s and the linearity of the ion path.

[0123] G4...Graph showing the relationship between the change in electrostatic voltage [V] and the paint adhesion rate. G5: A graph showing the relationship between the change in electrostatic voltage [V] and the gradient of the deposition amount in the thickness direction. G6: A graph showing the relationship between the change in paint particle diameter / pore diameter and the paint scattering concentration in the depth direction.

[0124] G7: A graph showing the relationship between the change in paint particle diameter / pore diameter and the gradient of the coating amount in the thickness direction. 1...Coating device (for positive electrode plates of lithium-ion secondary batteries) 2, 102...Painting chamber 2a...Main body 2b...Positive pressure chamber 2c...Pressure device 3, 103...Spraying equipment 4, 104...Ventilation equipment 5, 105...Paint supply device 51, 151...Nozzle 6, 106...Charging device 7...Reverse roller mechanism 7a~7h...Reverse roller 8a...(positive electrode current collector) supply roller 8b...Positive electrode plate winding roller 9, 109...Paint particle recovery device 101...second coating device 10...Lithium-ion secondary battery (secondary battery) 1M...Battery module 11...Battery case 12...Electrode body 13...Nonaqueous electrolyte 14...Positive external terminal 15...Negative external terminal 16...Positive current collecting terminal 17...Negative electrode current collector terminal 20...Negative electrode plate 21...Negative electrode current collector 22...Negative electrode composite material layer 23...Negative electrode current collector 30...Positive electrode plate (electrode) 31... Positive electrode current collector (porous current collector) 31a...Skeleton 31b...Vacancy 32...Positive electrode mixture layer 33...Positive electrode current collector 40...Separator

Claims

1. A method for manufacturing an electrode plate for a secondary battery, comprising spraying paint particles onto a porous current collector having a plate-like three-dimensional structure using a nozzle of a coating device to form a composite layer, the paint particles contain an active material; The coating particles have an average diameter D of the pores of the porous current collector. １ [μm] (d ５０ ) Average diameter D ２ [μm] (d ５０ ) A method for manufacturing an electrode plate for a secondary battery, characterized in that the coating device sprays the coating particles onto the porous current collector so as to penetrate the porous current collector in the thickness direction, thereby applying the coating material to the porous current collector.

2. The coating device adjusts the amount of the coating particles that adhere to the porous current collector by adjusting the amount of the coating particles that are discharged. The method for manufacturing an electrode plate for a secondary battery according to claim 1 .

3. The paint particles are charged, and the porous current collector is charged with a polarity different from that of the paint particles, so that the paint particles adhere to the porous current collector. The method for manufacturing an electrode plate for a secondary battery according to claim 1 .

4. The amount of the paint particles adhering to the porous current collector is adjusted by adjusting the potential of the porous current collector.

4. The method for manufacturing an electrode plate for a secondary battery according to claim 3.

5. The blower blows the paint particles onto the porous current collector at an air volume [m ３ The amount of the paint particles adhering to the porous current collector is adjusted by adjusting either the air flow rate [m / s] or the wind speed [m / s]. The method for manufacturing an electrode plate for a secondary battery according to claim 1 .

6. 2. The method for manufacturing an electrode plate for a secondary battery according to claim 1, wherein the porous current collector is wound around a roller in a long length and accommodated therein, and is then pulled out from the roller and coated with the paint particles in a coating chamber.

7. The method for manufacturing an electrode plate for a secondary battery according to claim 6, characterized in that the porous current collector is inverted in a direction perpendicular to the discharge direction of the nozzle and moved back and forth multiple times within the coating chamber to coat the front and back of the porous current collector.

8. After painting the porous current collector while turning it over, The coating particles have an average pore diameter D １ [μm] (d ５０ ) 80% or more of the average diameter D ２ [μm] (d ５０ ) The method for manufacturing an electrode plate for a secondary battery according to claim 7, characterized in that the paint particles are sprayed by a second coating device so as not to penetrate the porous current collector in the thickness direction, thereby applying the paint unevenly to only one side of the porous current collector.

9. A coating device for electrode plates of secondary batteries, which sprays paint particles from a nozzle onto a porous current collector having a plate-like three-dimensional structure to form a composite layer, A coating device for electrode plates of secondary batteries, characterized in that the coating device sprays the paint particles so as to penetrate the porous current collector in the thickness direction, thereby applying paint to the porous current collector.

10. The coating device adjusts the amount of the coating particles that adhere to the porous current collector by adjusting the amount of the coating particles that are discharged.

10. The coating device for electrode plates of a secondary battery according to claim 9.

11. a charging device that charges the paint particles and charges the porous current collector to a polarity different from that of the paint, thereby causing the paint particles to adhere to the porous current collector; The coating device for electrode plates of secondary batteries according to claim 10.

12. The amount of the paint particles adhering to the porous current collector is adjusted by adjusting the potential of the porous current collector. The coating device for electrode plates of secondary batteries according to claim 11.

13. A blower is provided to blow the paint particles onto the porous current collector, and the blower has an air volume [m ３ The amount of the paint particles adhering to the porous current collector is adjusted by adjusting either the air flow rate [m / s] or the wind speed [m / s]. The coating device for electrode plates of secondary batteries according to claim 10.

14. 11. The coating device for electrode plates of secondary batteries according to claim 10, further comprising a coating chamber, wherein the porous current collector is wound around a roller in a long length and accommodated therein, and is then pulled out from the roller and coated with the paint particles within the coating chamber.

15. The coating device for electrode plates of secondary batteries according to claim 14, further comprising a reversing roller mechanism that reverses the porous current collector in a direction perpendicular to the discharge direction of the nozzle within the coating chamber and moves it back and forth multiple times, thereby coating the porous current collector while reversing its front and back sides.

16. After painting the porous current collector while turning it over, The average diameter D of the pores of the porous current collector １ [μm] (d ５０ ) 80% or more of the average diameter D ２ [μm] (d ５０ 16. The coating device for an electrode plate of a secondary battery according to claim 15, further comprising an uneven coating device that performs uneven coating by spraying the paint particles having a thickness of 100 μm or more onto only one side of the porous current collector using a second coating device so that the paint particles do not penetrate the thickness of the porous current collector.

17. The coating device for electrode plates of secondary batteries as described in claim 15, characterized in that the reversing roller mechanism is provided with a positive pressure chamber that creates a positive pressure within the coating chamber to prevent the paint particles from leaking out of the coating chamber.

18. 15. The coating device for electrode plates of secondary batteries according to claim 14, further comprising a recovery device for recovering the paint particles that have passed through the porous current collector on the downstream side of the coating chamber.

Images