Sealing plate for lithium battery and method for manufacturing same

Abstract

Provided is a sealing plate 1 for closing an end part of a lithium battery 50, wherein: the sealing plate 50 comprises a rectangular frame-form metal flange 2, a resin sealing plate 3 formed in a state of closing the inside of the flange 2, and one and another metal electrode bodies 4, 5 that are respectively arranged on one short side and the other short side of the sealing plate 3; each of the electrode bodies 4, 5 is provided with rectangular plate-form external electrodes 4A, 5A that are arranged overlapping the battery outer surface of the sealing plate 3, and internal electrodes 4B, 5B that are connected to the external electrodes 4A, 5A and extend toward the interior of the battery through the sealing plate 3; and the sealing plate 3 integrally has an insulating part 6 covering an outer peripheral end surface that follows a pair of long sides and an outer peripheral end surface that follows one short side close to the short side of the flange 2, among the outer peripheral end surfaces of the external electrodes 4A, 5A.

Description

Lithium battery sealing plate and method of manufacturing same

[0001] The present invention relates to a sealing plate for a lithium battery used to close the end of the lithium battery, and a method for manufacturing the same.

[0002] A conventional battery sealing plate is disclosed, for example, in Patent Document 1. Patent Document 1 describes a sealing plate in which a pair of electrode terminals are provided in a penetrating state through a metal lid body, and an insulating sealing material is interposed between the lid body and each of the electrode terminals.

[0003] Japanese Patent Application Publication No. 2008-027823

[0004] Generally, lithium batteries are mass-produced and used in many devices, and therefore research and development is being conducted to make them smaller, lighter, and less expensive. Similar research and development is also being conducted on the sealing plates used in these batteries.

[0005] The present invention has been made in view of the above-described conventional situation, and aims to provide a high-quality sealing plate for a lithium battery that is made of resin, thereby enabling reduction in size, weight, and cost, and that has excellent insulation properties between metal parts, as well as a method for manufacturing the same.

[0006] The sealing plate for a lithium battery according to the present invention is a sealing plate for closing the end of a lithium battery, and comprises a metal flange in the shape of a rectangular frame, a resin sealing plate formed to seal the inside of the flange, and first and second metal electrode bodies arranged on one and the other short side of the sealing plate, respectively, each of the electrode bodies comprising a plate-shaped external electrode arranged on the sealing plate's outer surface outside the battery, and an internal electrode connected to the external electrode and extending through the sealing plate toward the inside of the battery, each of the external electrodes having a rectangular shape with long sides parallel to the long sides of the flange and short sides parallel to the short sides of the flange, and the sealing plate integrally comprising an insulating portion covering the outer peripheral end faces of each external electrode that extend along a pair of long sides and the outer peripheral end face that extends along one short side closest to the short side of the flange.

[0007] The method for producing a lithium battery sealing plate according to the present invention uses a molding device that forms a molding space for the sealing plate between one and another molding dies, and is characterized by comprising the steps of setting a metal flange and a pair of electrode bodies in one of the molding dies, filling the molding space with molten resin under pressure after closing the one and another molding dies, integrating the metal flange and both electrode bodies with the resin sealing plate as the molten resin solidifies, and opening the one and another molding dies to release the lithium battery sealing plate.

[0008] The lithium battery sealing plate and its manufacturing method according to the present invention, by adopting the above-described configuration, can be easily manufactured by, for example, insert injection molding, and has a structure in which metal parts and resin parts are integrated. The lithium battery sealing plate and its manufacturing method can not only achieve size and weight reduction and cost reduction by reducing the number of parts such as gaskets, but also provide a high-quality sealing plate with excellent insulation between metal parts, contributing to size and weight reduction (thinning and lightening), cost reduction, and quality improvement of lithium batteries.

[0009] 1A and 1B are a plan view (A), a side view (B) of the long side of the flange, a cross-sectional view (C) along line C-C in FIG. 1A, a side view (D) of the short side of the flange, and a cross-sectional view (E) along line E-E in FIG. 1A, showing one embodiment of a sealing plate for a lithium battery according to the present invention.

[0022] FIG. 1A is a side view (A) and a plan view (B) showing the flange and a pair of electrode assemblies in an exploded state.

[0023] FIG. 1B is a perspective view (A) of a sealing plate for a lithium battery, and a cross-sectional view (B) of a lithium battery equipped with the sealing plate.

[0024] FIG. 1B is a diagram showing a method for manufacturing a sealing plate for a lithium battery, showing a cross-sectional view (A) of a molding device together with the flange and a pair of electrode assemblies, and a cross-sectional view (B) showing the flange and a pair of electrode assemblies set in one of the molds.

[0025] Continuing from FIG. 4, these are diagrams showing a method for manufacturing a sealing plate for a lithium battery, showing a cross-sectional view (A) of a mold in a closed state, a cross-sectional view (B) of a molding space filled with molten resin, and a cross-sectional view (C) of a state at the time of mold release.

[0026] FIG. 1C is an explanatory cross-sectional view showing another embodiment of a sealing plate for a lithium battery.

[0010] Specific examples of the lithium battery sealing plate and its manufacturing method of the present invention are shown and described in Figures 1 to 6. The lithium battery sealing plate (hereinafter simply referred to as "sealing plate") 1 shown in Figures 1 and 2 is used to close the end of a lithium battery and includes a rectangular frame-shaped metal flange 2, a resin sealing plate 3 formed to seal the inside of the flange 2, and first and second metal electrode bodies 4, 5 disposed on one and the other short sides of the sealing plate 3, respectively. The dashed-dotted lines in Figure 2 indicate the joining positions of the respective components, and the two-dot chain line at the top virtually shows the electrode bodies 4, 5 relative to the flange 2.

[0011] The metal flange 2 is made of a metal such as aluminum alloy, although the material is not limited thereto, and has a long, narrow rectangular shape to accommodate a thin lithium battery. The resin sealing plate 3 is formed by insert injection molding, which will be described later, so as to seal the inside of the flange 2. It has a mounting hole 3A for a relief valve (not shown) in the center of the long side of the flange 2, and an electrolyte injection hole 3B between this mounting hole 3A and one side (the lower side in FIG. 1A ) of the electrode body 5. The resin material of the sealing plate 3 will be described later.

[0012] The one and the other electrode bodies 4, 5 are essentially positive and negative electrodes, and are made of a material with good conductivity such as a copper alloy. As shown in Fig. 3(A) , the two electrode bodies 4, 5 each include a plate-shaped external electrode 4A, 5A that is placed on the outer surface of the battery of the sealing plate 3, and an internal electrode 4B, 5B that is connected to the external electrode 4A, 5A and extends through the sealing plate 3 toward the inside of the battery.

[0013] The external electrodes 4A, 5A are rectangular plate-like members with long sides parallel to the long sides of the flange 2 and short sides parallel to the short sides of the flange 2, and have slits 4C, 5C penetrating through them in the thickness direction. The external electrodes 4A, 5A are disposed on the sealing plate 3 near one and the other short sides of the flange 2, respectively.

[0014] The ends of the internal electrodes 4B, 5B on the outer side of the battery are fitted and fixed into the slits 4C, 5C of the external electrodes 4A, 5A. The internal electrodes 4B, 5B penetrate the sealing plate 3 and bend in opposite directions inside the battery, then bend in parallel directions at their ends, forming an overall crank shape. The shape of the internal electrodes 4B, 5B can be changed as appropriate depending on the internal configuration of the battery, etc.

[0015] The external electrodes 4A, 5A and the internal electrodes 4B, 5B are joined to each other by, for example, welding, or may alternatively be screwed together. The external electrodes 4A, 5A are basically plate-shaped, but can be formed into various shapes, such as by providing a convex portion on the upper surface or by making the external electrodes 4B, 5B protrude, depending on the shape of the connector to which the lithium battery is connected.

[0016] In the sealing plate 1, the sealing plate 3 is integrally formed with an insulating portion 6 that covers at least a portion of the outer peripheral end face of each external electrode 4A, 5A that is close to the flange 2. More specifically, the sealing plate 1 is integrally formed with an insulating portion 6 that covers, of the outer peripheral end faces of each external electrode 4A, 5A, the outer peripheral end faces that extend along a pair of long sides and the outer peripheral end face that extends along one short side that is close to the short side of the flange 2. In other words, the insulating portion 6 is formed so as to cover three outer peripheral end faces of both external electrodes 4A, 5A excluding the opposing outer peripheral end faces.

[0017] Here, it is desirable that the insulating portion 6 be of a height that is flush with the upper surfaces of the external electrodes 4A, 5A, i.e., a height that covers the entire outer peripheral end surfaces of the external electrodes 4A, 5A. However, it is also possible to make the insulating portion 6 slightly lower than the upper surfaces of the external electrodes 4A, 5A, as in the illustrated example, or to make it higher than the upper surfaces, and it is desirable that the insulating portion 6 have a height that is at least about half the thickness of the external electrodes 4A, 5A.

[0018] As shown in Fig. 3(B), the sealing plate 1 having the above-described configuration is fixed to the open end of the case of the lithium battery 50 by laser welding or the like around the entire periphery of the flange 2 to close the open end, and both internal electrodes 4B, 5B are electrically connected to the wound electrode 51 inside the battery. A relief valve (not shown) is attached to the mounting hole 3A, and a cap (not shown) is fitted and fixed into the injection hole 3B after the electrolyte is injected (see Fig. 3(A)).

[0019] Next, a method for manufacturing the sealing plate 1 having the above configuration will be described. This manufacturing method uses a molding device 10, as shown in Figure 4(A), which forms a molding space 13 for the sealing plate 3 between one and other molding dies 11, 12. One molding die 11 on the left side in Figure 4 is a movable die that can move toward and away from the other molding die 12, and has mounting portions 11A, 11B, and 11C for the flange 2 and the electrode bodies 4 and 5 on the molding space 13 side. Although not shown, one molding die 11 is provided with an ejection mechanism for pushing out the molded sealing plate 1 and releasing it from the mold.

[0020] The other molding die 12 on the right side in Fig. 4 is a fixed die and has protrusions 12A, 12B on the molding space 13 side for forming the elongated mounting hole 3A and the circular liquid injection hole 3B, as well as a resin supply device (not shown) and two gates G1, G2 for injecting molten resin into the molding space 13. The gates G1, G2 in the illustrated example are located at positions spaced toward the center of the molding space 13 from the external electrodes 4A, 5A of the two electrode bodies 4, 5 set in the molding space 13, that is, open on both sides in the major axis direction of the mounting hole 3A in the illustrated example (see Fig. 1(A)). Therefore, two gate marks G, G are formed on the surface of the sealing plate 3, as shown in Fig. 1(A).

[0021] The method for manufacturing the sealing plate 1 includes a step of setting the metal flange 2 and the pair of electrode bodies 4 and 5 in the mounting portions 11A, 11B, and 11C of one of the molding dies 11, as shown in FIG. 4(B).

[0022] For such metal parts, it is desirable to use parts whose surfaces have been roughened in advance by chemical conversion treatment, laser processing, or the like at the locations where the molten resin R (see FIG. 5(B)) comes into contact during insert injection molding. By increasing the surface area through surface roughening before injection molding, the molten resin R can more easily penetrate into the irregularities, increasing adhesion such as shear strength, and also improving the airtightness of the joint, which can prevent corrosive gases generated by deterioration of the electrolyte over time from being released to the outside.

[0023] Specific examples of such roughening treatment methods include a surface treatment method (Patent No. 3954379) in which the metal surface is lightly corroded by immersion in a chemical solution containing hydrazine, ammonia, and a water-soluble amine to form irregularities, and a method in which fine irregularities are mechanically formed by laser treatment (Light Metal Welding Association Journal 58(2), pp. 65-68, 2020-02, Light Metal Welding Association).

[0024] Since the flange 2 will later be fixed to the case of the lithium battery 50 by welding, the area to be welded may be masked to maintain smoothness, and the area that will come into contact with the molten resin may be roughened.

[0025] The manufacturing method also includes a step of moving one of the molds 11 forward to close both molds 11 and 12, as shown in FIG. 5(A), and then pressurizing and filling the molding space 13 with molten resin R through gates G1 and G2, as shown in FIG. 5(B).

[0026] Furthermore, the above manufacturing method includes a step of integrating the metal flange 2 and both electrode bodies 4, 5 with the resin sealing plate 3 as the molten resin R solidifies, and a step of retracting one of the molding dies 11 to open both molding dies 11, 12, as shown in FIG. 5(C), and releasing the sealing plate 1 from one of the molding dies 11 by an ejector mechanism (not shown).

[0027] At this time, the direction in which the molten resin R is filled may be either horizontal or vertical, but it is more preferable to use a vertical molding machine that fills in the vertical direction, as this makes it easier to fix parts such as flanges and electrodes within the mold.

[0028] That is, insert injection molding is preferably performed in the manufacturing method of the sealing plate 1. In this case, the material of the resin sealing plate 3 is not particularly limited, but in a more preferred embodiment, at least one resin composition selected from polybutylene terephthalate (PBT), polyamide (PA), polyphenylene sulfide (PPS), and mixed resins thereof can be used.

[0029] Furthermore, the material for the sealing plate 3 may be any resin composition that has thermal cycling performance during both rest and use. However, since the linear expansion coefficient of the sealing plate 3 differs from that of the aluminum alloy or copper alloy used as the electrodes, cracks may occur due to thermal cycling (heat cycles). Therefore, in order to mitigate thermal shock that occurs, it is desirable for the sealing plate 3 to be made of a resin composition containing an ethylene-acrylic acid ester copolymer, and it is more desirable for the ethylene-acrylic acid ester copolymer to be 3% by mass or more and 10% by mass or less.

[0030] For example, by making the ethylene-acrylic acid ester copolymer 3% by mass or more and 10% by mass or less, the mechanical properties are excellent while the decrease in chemical resistance to the electrolyte solution is small, and the difference in the linear expansion coefficient from the metal parts can mitigate the thermal shock that occurs, thereby extending the thermal cycle resistance life of the sealing plate.

[0031] There are several types of ethylene-acrylic acid esters depending on their copolymerization components and reactive functional groups, such as ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, ethylene-acrylic acid ester-maleic anhydride copolymer, ethylene-acrylic acid ester-glycidyl ester copolymer, etc. Examples of ethylene-acrylic acid ester-maleic anhydride copolymers include BONDINE AX8390 and TX8030 (trade names) manufactured by SK global chemical, and examples of ethylene-acrylic acid ester-glycidyl ester copolymers include Lotader AX8700 and AX8750 (trade names) manufactured by SK global chemical, and Bondfast 7M and 7L (trade names) manufactured by Sumitomo Chemical Co., Ltd.

[0032] Furthermore, the type of copolymer or copolymerization ratio of such an ethylene-acrylic acid ester copolymer can be determined arbitrarily within the scope of the present invention depending on the desired product shape, resin layer thickness, molding temperature, and the mechanical properties of the desired resin composition, and two or more types may be mixed and used depending on the purpose. Furthermore, the material for the sealing plate 3 may be a resin mixed with reinforcing fibers such as glass fiber or carbon fiber. Furthermore, the resin composition may contain antioxidants, flame retardants, copper inhibitors, plasticizers, mold release agents, colorants, and the like depending on the purpose.

[0033] Such a resin composition has a shear rate of 1.0×10 at a molding temperature. ３ It is desirable that the melt viscosity at 1 / sec is 150 to 2,000 Pa·s. Within this viscosity range, even when the dimensional design of the sealing plate is thin, the resin has high fluidity, allowing molding without insufficient filling at the end of the flow (short shot). In addition, the resin has a good balance between fluidity and mechanical properties, good mechanical properties such as tensile strength and shear strength, and an excellent product life in a thermal cycle environment.

[0034] The sealing plate 1 having the above configuration can be easily mass-produced by insert injection molding, and has a structure in which the metal parts, that is, the flange 2 and the pair of electrode bodies 4, 5, are integrated with the resin part, that is, the sealing plate 3. Furthermore, in order to realize a thin lithium battery, the sealing plate 1 has an elongated rectangular shape, so that the metal flange 2 and the external electrodes 4A, 5A of the metal electrode bodies 4, 5 are close to each other.

[0035] In contrast, in the above-described sealing plate 1, the resin sealing plate 3 has an insulating portion 6 integrally formed on the outer peripheral end faces of the external electrodes 4A, 5A, particularly in the portion covering the outer peripheral end faces near the flange 2, so that the creepage distance of the insulating resin between the connection terminals 4A, 5A and the flange 2 is long, making it possible to prevent accidental contact (short-circuiting) between the flange 2 and the electrode bodies 4, 5 due to other equipment, metal pieces, etc. With this structure, the designed cross-sectional area of ​​the weld line where the molten resin rejoins is increased, making it possible to withstand stress caused by differences in the linear expansion coefficient and improving the heat cycle life of the component.

[0036] In this way, the above-described lithium battery sealing plate and its manufacturing method can realize reductions in size and weight and cost, and can also provide a high-quality sealing plate 1 with excellent insulation between metal parts, thereby contributing to reductions in size and weight (thinner and lighter), cost reductions, and improved durability such as heat cycle resistance of lithium batteries.

[0037]

[0039] An embodiment of the lithium battery sealing plate of the present invention will be specifically described. Example 1: PPS resin powder (A-1) (PPS powder manufactured by Tosoh Corporation, melting point 280°C, viscosity after polymerization 226 poise, viscosity after air curing treatment 672 poise (measurement conditions: die diameter 0.5 mm x length 2.0 mm, measurement temperature 315°C, measured using a high-temperature flow tester), polyethylene (B-1) (ethylene-ethyl acrylate-maleic anhydride copolymer; (product name) AX8390 manufactured by SKGC), glass fiber (C) (fiber diameter approximately 10.5 μm, (product name) ECS03T-760H manufactured by Nippon Electric Glass Co., Ltd.), epoxy compound (D) manufactured by DIC Corporation Epiclon 3050 (epoxy equivalent weight: approximately 780 g / eq), (E) mold release agent (trade name: Lightamide WH-255, manufactured by Kyoeisha Chemical Co., Ltd.), and (F) colorant (#950, manufactured by Mitsubishi Chemical Corporation) were weighed out in the formulations shown in Table 1 and kneaded in a twin-screw kneader (KZW-15, manufactured by Technovel Co., Ltd.; cylinder diameter (D) 15 mm, cylinder length (L) 900 mm, L / D = 60; kneading temperature: 300°C). The molten resin extruded from the die holes was conveyed on a conveyor while being air-cooled, and the resulting strands were cut to obtain pellets with a diameter of approximately 5 mm and a length of approximately 6 mm. At this time, the melt viscosity of the resin composition was 2.4 × 10 ２ It was Pa·s.

[0038] Sealing plate components (frame, two electrodes, and two connection terminals, a total of five components) whose metal surfaces had been roughened in advance were set in a molding die, and the resin pellets obtained above were placed in the hopper of an in-line screw electric injection molding machine (S75D manufactured by Sumitomo Heavy Industries, Ltd.; cylinder diameter 28 mm). The pellets were melted at 300°C and insert injection molded under the following conditions: filling speed 35-50 mm / sec, holding pressure: 60 MPa (7 seconds), number of mold gates: 2, molding cycle time: approximately 55 seconds. A sealing plate prototype was produced using the sealing plate for lithium batteries, with a length of 125 mm x width of 16 mm, a frame width of 3 mm, and an electrode length of 60 mm.

[0039] Example 2 Using PPS resin powder (A-2) (PPS resin powder manufactured by Tosoh Corporation, melting point 281°C, viscosity after polymerization 115 poise, viscosity after air curing treatment 245 poise (measurement conditions are the same as in Example 1)), resin composition pellets were prepared in the blending amounts shown in Table 1, and a sealing plate for a lithium battery was produced.

[0040] Example 3 Pellets of a resin composition having the composition shown in Table 1 were prepared using PPS resin powder (A-3) (PPS resin powder manufactured by Tosoh Corporation, melting point 280°C, viscosity after polymerization 135 poise, viscosity after air curing treatment 334 poise (measurement conditions were the same as in Example 1)), and a sealing plate for a lithium battery having the same shape as in Example 1 was produced.

[0041] Examples 4 and 5 Pellets of a resin composition having the composition shown in Table 1 were prepared using PPS resin powder (A-1) (PPS powder manufactured by Tosoh Corporation, melting point 280°C, viscosity after polymerization 226 poise, viscosity after air curing treatment 672 poise (measurement conditions were the same as in Example 1)), and a sealing plate for a lithium battery having the same shape as in Example 1 was produced.

[0042] Example 6 A sealing plate for a lithium battery having the same shape as in Example 1 was produced by insert injection molding at 270 to 280°C using commercially available polyamide 66 resin pellets (B) (melting point: approximately 260°C, 80G33L manufactured by DuPont (glass fiber content: 33%), impact resistance modifier blended).

[0043] Example 7 A sealing plate for a lithium battery having the same shape as in Example 1 was produced by insert injection molding at 240 to 250°C using commercially available polybutylene terephthalate resin pellets (B) (melting point: approximately 222°C, DURANEX 531HS (glass fiber blending amount: 30%) manufactured by WinTech Polymer Co., Ltd., and blended with an impact resistance modifier).

[0044] The resin composition pellets and lithium battery sealing plates obtained in each example were subjected to the following performance evaluations. <Measurement of Melt Shear Viscosity of Resin Composition> Using a Rheolograph 25 manufactured by Goettfelt, pre-dried PPS resin composition pellets were melted in the cylinder of the device, and the melt shear viscosity was measured at a temperature of 310°C and a shear rate of 1.0 x 10 ３The shear viscosity of the resin composition was determined from the shear stress generated when the piston was pressed in, using a speed of 1 / sec. A measuring die having a diameter of 1 mm and a length of 20 mm was used. The measurement results are shown in Table 1.

[0045] <Heat cycle test of sealing plate> Using a thermal shock tester TSA-103ES-W manufactured by Espec Corporation, sealing plate samples were placed in a high temperature chamber at +160°C and a low temperature chamber at -40°C (30 minutes each, 1 hour per cycle), and the appearance of the test pieces was inspected for cracks visually or using a magnifying glass every 20 cycles. Six pieces were tested for each test, and the number of times when cracks occurred in half of them was taken as the heat cycle life (cycles). The results are also shown in Table 1.

[0046]

[0047] The operation and advantages of the embodiment of the lithium battery sealing plate and method for manufacturing the same according to the present invention described above will now be described. The method for manufacturing a lithium battery sealing plate described above uses a molding device 10 in which gates G1, G2 are located at positions toward the center of the molding space 13 and away from the external electrodes 4A, 5A of the electrode assemblies 4, 5 set in the molding space 13. As a result, according to the above manufacturing method, there is no insulating portion or the height of the insulating portion is low between the opposing outer peripheral end faces of the external electrodes 4A, 5A, so that little resin remains here (between the opposing outer peripheral end faces of the external electrodes 4A, 5A), increasing the filling speed of the molten resin R into the external electrodes 4A, 5A and making it possible to ensure the molding pressure of the molten resin R in the narrow space in which the insulating portion 6 is molded.

[0048] Furthermore, in the above manufacturing method, for example, by offsetting the positions of the gates G1 and G2 in opposite directions relative to the center line of the flange 2 in the long side direction (for example, line C-C in FIG. 1A), a long diagonal weld line is formed, thereby increasing the mechanical strength of the sealing plate 3 against the internal pressure of the battery.

[0049] Furthermore, since the above manufacturing method uses insert injection molding, it is easy to form a partition wall 15 or the like to ensure the flow of molten resin R inside the mounting hole 3A, as shown in Figure 6, and there is a high degree of freedom in the shape. Also, the partition wall 15 may be removed after the sealing plate 1 is formed and a relief valve may be attached, or it may itself have the function of a relief valve. In this case, the thickness of the partition wall 15 may be set so that it ruptures at a predetermined pressure when the internal pressure of the battery increases, and because there is a high degree of freedom in the shape as described above, it is also easy to form a notch for rupturing.

[0050] The specific configuration of the sealing plate for a lithium battery and the method for manufacturing the same according to the present invention is not limited to the above-described embodiment, and can, of course, be modified as appropriate without departing from the spirit and scope of the present invention. In addition, while the above-described embodiment illustrates an example in which the flange and the pair of electrodes are integrated with the sealing plate, anything that is heat resistant to the molten resin (sealing plate) can be integrated with the sealing plate, and for example, a relief valve can also be integrated.

[0051] REFERENCE SIGNS LIST 1 Sealing plate 2 Flange 3 Sealing plate 3A Mounting hole 3B Injection hole 4 One electrode body 4A External electrode 4B Internal electrode 4C Through slit 5 Other electrode body 5A External electrode 5B Internal electrode 5C Through slit 6 Insulating portion 10 Molding device 11 One molding die 11A, 11B, 11C Metal member mounting portion 12 Other molding die 12A Mounting hole forming convex portion 12B Injection hole forming convex portion 13 Molding space 50 Lithium battery 51 Wound electrode G Gate mark G1, G2 Gate R Molten resin

Claims

1. A sealing plate for closing an end of a lithium battery, comprising: a metal flange having a rectangular frame shape; a resin sealing plate formed to close the inside of the flange; and first and second metal electrode bodies respectively disposed on one and the other short sides of the sealing plate. Each of the electrode bodies includes a plate-shaped external electrode disposed overlapping the battery outer surface of the sealing plate, and an internal electrode connected to the external electrode and extending inwardly of the battery through the sealing plate. Each of the external electrodes has a rectangular shape having a long side parallel to the long side of the flange and a short side parallel to the short side of the flange. The sealing plate integrally has an insulating portion covering outer peripheral end surfaces along a pair of long sides and an outer peripheral end surface along one short side close to the short side of the flange among the outer peripheral end surfaces of the respective external electrodes. A sealing plate for a lithium battery, characterized by the above.

2. The sealing plate for a lithium battery according to claim 1, wherein the resin which is the material of the sealing plate contains at least one resin selected from the group consisting of polybutylene terephthalate (PBT), polyamide (PA), and polyphenylene sulfide (PPS).

3. The sealing plate for a lithium battery according to claim 2, wherein the resin material is composed of a resin composition containing an ethylene-acrylic acid ester copolymer.

4. The sealing plate for a lithium battery according to claim 3, wherein the ethylene-acrylic acid ester copolymer in the resin material is 3% by mass or more and 10% by mass or less.

5. A sealing plate for closing an end of a lithium battery, comprising a metal flange having a rectangular frame shape, a resin sealing plate formed to close the inside of the flange, and first and second metal electrode bodies respectively disposed on one and the other short sides of the sealing plate. Each of the electrode bodies includes a plate-shaped external electrode disposed overlapping the battery outer surface of the sealing plate, and an internal electrode connected to the external electrode and extending inwardly of the battery through the sealing plate. Each of the external electrodes has a rectangular shape having a long side parallel to the long side of the flange and a short side parallel to the short side of the flange. When manufacturing a sealing plate for a lithium battery integrally having an insulating portion that covers outer peripheral end faces along a pair of long sides and an outer peripheral end face along one short side close to the short side of the flange among the outer peripheral end faces of each of the external electrodes, a molding apparatus for forming a molding space for the sealing plate between a first and a second mold is used. The method includes a step of setting a metal flange and a pair of electrode bodies in the first mold, a step of pressure filling the molding space with molten resin after closing the first and second molds, a step of integrating the metal flange, the two electrode bodies, and the resin sealing plate as the molten resin solidifies, and a step of opening the first and second molds to release the sealing plate for the lithium battery. A method for manufacturing a sealing plate for a lithium battery, characterized by comprising the above steps.

6. The method for manufacturing a sealing plate for a lithium battery according to claim 5, wherein the molding apparatus has a structure in which a gate is disposed at a position spaced from the external electrodes of the two electrode bodies set in the molding space toward the center side of the molding space, and pressure filling of the molten resin is performed from the gate.

7. The method for manufacturing a sealing plate for a lithium battery according to claim 5, wherein at least a portion of the metal flange and each electrode body that comes into contact with the molten resin is subjected to roughening treatment in advance.

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