Sealing plate for lithium battery and method of manufacturing the same

Abstract

To provide a high-quality sealing plate for a lithium battery which is capable of achieving downsizing, reduction of weight, reduction of cost, etc., and further improved in insulation property.SOLUTION: A sealing plate 1 for closing an end of a lithium battery 50 comprises: a metallic flange 2 in a rectangular frame shape; a resin sealing plate 3 which is formed in a state where the inside of the flange 2 is closed; and one and other electrode bodies 4 and 5 which are disposed on one and other short sides of the sealing plate 3. The electrode bodies 4 and 5 include external electrodes 4A and 5A in a rectangular plate shape disposed while being overlapped on a battery outer face of the sealing plate 3; and internal electrodes 4B and 5B which are connected to the external electrodes 4A and 5A, penetrate the sealing plate 3 and extend in a battery inside direction. The sealing plate 3 integrally includes an insulation part 6 covering, in the outer peripheral end faces of the external electrodes 4A and 5A, the outer peripheral end face along a pair of long sides and the outer peripheral end face along a short side on one side proximate to a short side of the flange 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[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. [Background technology]

[0002] An example of a conventional battery sealing plate is disclosed 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 electrode terminal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-027823 Summary of the Invention [Problem to be solved by the invention]

[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. [Means for solving the problem]

[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. [Effects of the Invention]

[0008] The lithium battery sealing plate and its manufacturing method according to the present invention employ the above-described configuration, and can be easily manufactured by, for example, insert injection molding, and have 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 (thinner thickness and lighter weight), cost reduction, and high quality of lithium batteries. [Brief explanation of the drawings]

[0009] [Figure 1] 1A is a plan view showing one embodiment of a sealing plate for a lithium battery according to the present invention; FIG. 1B is a side view of the long side of a flange; FIG. 1C is a cross-sectional view taken along line CC in FIG. 1A; FIG. 1D is a side view of the short side of a flange; and FIG. 1E is a cross-sectional view taken along line EE in FIG. 1A. [Figure 2] 1A is a side view showing a flange and a pair of electrode bodies in an exploded state, and FIG. 1B is a plan view showing the flange and a pair of electrode bodies in an exploded state. [Figure 3] 1A is a perspective view of a sealing plate for a lithium battery, and FIG. 1B is a cross-sectional view of a lithium battery equipped with the sealing plate. [Figure 4] 1A and 1B are diagrams showing a method for manufacturing a sealing plate for a lithium battery, in which FIG. 1A is a cross-sectional view showing a molding device together with a flange and a pair of electrode bodies, and FIG. 1B is a cross-sectional view showing the state in which the flange and a pair of electrode bodies are set in one of the molding dies. [Figure 5] 5A is a cross-sectional view showing the state in which the molding die is closed, FIG. 5B is a cross-sectional view showing the state in which the molding space is filled with molten resin, and FIG. 5C is a cross-sectional view showing the state at the time of mold release. [Figure 6] FIG. 10 is an explanatory cross-sectional view showing another embodiment of a sealing plate for a lithium battery. DETAILED DESCRIPTION OF THE INVENTION

[0010] A specific example of the sealing plate for a lithium battery and the method for producing the same of the present invention will be described with reference to FIGS. 1 and 2 shows a lithium battery sealing plate (hereinafter simply referred to as "sealing plate") 1, which closes the end of a lithium battery, and includes a metal flange 2 forming a rectangular frame, a resin sealing plate 3 formed to seal the inside of the flange 2, and first and second metal electrode bodies 4, 5 arranged on one and the other short sides of the sealing plate 3. Note that the dashed dotted lines in Fig. 2 indicate the joining positions of the respective parts, and the double-dashed 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 the electrode body 5 on one side (the lower side in FIG. 1A). The resin material of this sealing plate 3 will be described later.

[0012] The electrode bodies 4 and 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 electrode bodies 4 and 5 each include a plate-shaped external electrode 4A, 5A that is placed on the outer surface of the battery, i.e., 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 internal electrodes 4B, 5B have their outer ends on the battery's exterior fitted into the slits 4C, 5C of the external electrodes 4A, 5A. The internal electrodes 4B, 5B penetrate the sealing plate 3, bend in opposite directions inside the battery, and 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 welding, for example, or may be screwed together. The external electrodes 4A, 5A are basically plate-shaped, but can be formed into various shapes, such as by providing a protrusion 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 integral with an insulating portion 6 that covers at least a portion of the outer peripheral end faces of the external electrodes 4A, 5A that is adjacent to the flange 2. More specifically, the sealing plate 1 is integral with an insulating portion 6 that covers, of the outer peripheral end faces of the external electrodes 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 adjacent to the short side of the flange 2. In other words, the insulating portion 6 is formed so as to cover the three outer peripheral end faces of the 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 filling 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 Figure 4 is a fixed die and has protrusions 12A, 12B on the molding space 13 side that form the elongated mounting hole 3A and the circular 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. In the illustrated example, the gates G1, G2 are located at positions spaced away from the outer electrodes 4A, 5A of the two electrode bodies 4, 5 set in the molding space 13 toward the center of the molding space 13, that is, on both sides of the mounting hole 3A in the major axis direction (see Figure 1(A)). Therefore, two gate marks G, G are formed on the surface of the sealing plate 3, as shown in Figure 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 or laser processing at the points where the molten resin R (see Figure 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 uneven surfaces, improving adhesion such as shear strength. In addition, improving the airtightness of the joints 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 immersed in a chemical solution containing hydrazine, ammonia, and a water-soluble amine to mildly corrode the surface and 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 be fixed to the case of the lithium battery 50 later 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 advancing one of the molding dies 11 to close both molding dies 11 and 12, as shown in FIG. 5(A), and then pressurizing and filling molten resin R into the molding space 13 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] In this case, the direction in which the molten resin R is filled can 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 shocks that may occur, it is desirable to use 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 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, and examples thereof include 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 Co., Ltd. Examples of ethylene-acrylic acid ester-glycidyl ester copolymers include Lotader AX8700 and AX8750 (trade names) manufactured by SK global chemical Co., Ltd., 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, thickness of the resin layer, molding temperature, desired mechanical properties of the resin composition, etc., and two or more types may be mixed and used depending on the purpose. The material for the sealing plate 3 may be a mixture of resin and reinforcing fibers such as glass fiber or carbon fiber. Furthermore, the resin composition may contain antioxidants, flame retardants, copper inhibitors, plasticizers, release agents, colorants, etc. 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 for the melt viscosity at 1 / sec to be 150 to 2,000 Pa·s. If the viscosity is within this range, the resin will have high fluidity even when the sealing plate is designed to be thin, allowing molding without insufficient filling at the end of the flow (short shot). It also has a good balance of fluidity and mechanical properties, with good mechanical properties such as tensile strength and shear strength, and 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 achieve 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 or metal pieces, etc. This structure increases the designed cross-sectional area of the weld line where the molten resin rejoins, 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-mentioned lithium battery sealing plate and its manufacturing method can achieve miniaturization, weight reduction, and cost reduction, and can also provide a high-quality sealing plate 1 with excellent insulation between metal parts, contributing to miniaturization and weight reduction (thinning and lightening), cost reduction, and high durability such as heat cycle resistance of lithium batteries.

[0037] An embodiment of the sealing plate for a lithium battery according to the present invention will now be described in detail. 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 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 Epicron 3050 (epoxy equivalent weight approximately 780 g / eq), (E) mold release agent (Kyoeisha Chemical Co., Ltd. (trade name) Lightamide WH-255), and (F) colorant (Mitsubishi Chemical Corporation #950) were weighed out in the formulation shown in Table 1 and mixed in a twin-screw mixer (Technovel KZW-15; cylinder diameter (D) 15 mm, cylinder length (L) 900 mm, L / D = 60; mixing temperature: 300°C). The molten resin extruded from the die hole was conveyed on a conveyor while being air-cooled, and the resulting strands were cut to obtain pellets approximately 5 mm in diameter and 6 mm in length. The melt viscosity of the resin composition was 2.4 x 10 2 It was Pa·s.

[0038] The sealing plate components (frame, two electrodes, and two connection terminals, a total of five components) with pre-roughened metal surfaces were placed in a mold, and the resin pellets obtained above were placed in the hopper of an inline screw electric injection molding machine (Sumitomo Heavy Industries, Ltd. S75D; cylinder diameter 28 mm). They were melted at 300°C and then insert-injected to produce a sealing plate prototype under the following conditions: filling speed 35–50 mm / s, holding pressure: 60 MPa (7 s), number of mold gates: 2, molding cycle time: approximately 55 s). The shape of the lithium battery sealing plate was 125 mm long x 16 mm short, with 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 were the same as in Example 1)), resin composition pellets were prepared in the amounts shown in Table 1, and sealing plates for lithium batteries were 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, DuPont 80G33L (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 manufactured by WinTech Polymer Co., Ltd. (glass fiber content: 30%), impact resistance modifier blended).

[0044] The resin composition pellets and lithium battery sealing plates obtained in each example were subjected to the following performance evaluations. <Melt shear viscosity measurement of resin composition> Using a Goettfeld Rheolograph 25, pellets of the PPS resin composition that had been dried in advance were melted in the cylinder of the device, and the measurement temperature was 310°C and the shear rate was 1.0 × 10 3 The 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 with a diameter of 1 mm and a length of 20 mm was used. The measurement results are shown in Table 1.

[0045] <Sealing plate heat cycle test> Using an Espec Corporation thermal shock chamber TSA-103ES-W, 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 visually or with a magnifying glass every 20 cycles for cracks. Six pieces were tested for each cycle, and the number of times when cracks appeared in half of them was taken as the heat cycle life (cycles). The results are also shown in Table 1.

[0046] [Table 1]

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

[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 CC 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 smooth flow of molten resin R inside the mounting hole 3A, as shown in FIG. 6, and there is a high degree of freedom in the shape. Furthermore, the partition wall 15 may be removed after the sealing plate 1 is formed and a relief valve may be installed, or it may itself function as 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 since 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 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. [Explanation of symbols]

[0051] 1 Sealing plate 2 flanges 3 Sealing plate 3A mounting hole 3B Injection hole 4 One electrode body 4A external electrode 4B Internal electrode 4C Through slit 5 The other electrode body 5A external electrode 5B Internal electrode 5C Through slit 6 Insulation 10 Molding equipment 11 One of the molds 11A, 11B, 11C Metal member attachment part 12 The other mold 12A Mounting hole forming protrusion 12B Convex portion for forming injection hole 13 Molding space 50 lithium batteries 51 Wound electrode G Gate marks G1, G2 gates R Molten resin

Claims

1. A sealing plate that closes an end of a lithium battery, a metal flange forming a rectangular frame; a resin sealing plate formed to close the inside of the flange; one and the other electrode bodies made of metal are respectively arranged on one and the other short side sides of the sealing plate, each of the electrode bodies includes a plate-shaped external electrode disposed on the outer surface of the sealing plate of 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 has a rectangular shape having long sides parallel to the long sides of the flange and short sides parallel to the short sides of the flange, a sealing plate for a lithium battery, characterized in that the sealing plate integrally has an insulating portion that covers, of the outer peripheral end surfaces of each of the external electrodes, the outer peripheral end surfaces along a pair of long sides and the outer peripheral end surface along one short side that is close to the short side of the flange.

2. 2. The sealing plate for a lithium battery according to claim 1, characterized in that the resin 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. 3. The sealing plate for a lithium battery according to claim 2, wherein the material resin is made of a resin composition containing an ethylene-acrylic acid ester copolymer.

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

5. a metal flange that forms a rectangular frame-like sealing plate that closes an end of the lithium battery; a resin sealing plate formed to close the inside of the flange, and first and second metal electrode bodies respectively disposed on one and second short side sides of the sealing plate, each of the electrode bodies includes a plate-shaped external electrode disposed on the outer surface of the sealing plate of 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 has a rectangular shape having long sides parallel to the long sides of the flange and short sides parallel to the short sides of the flange, When manufacturing a sealing plate for a lithium battery, the sealing plate has an integral insulating portion that covers, of the outer peripheral end faces of the external electrodes, the outer peripheral end faces along a pair of long sides and the outer peripheral end face along one short side that is close to the short side of the flange, a molding device that forms a molding space for the sealing plate between one and the other molding dies; a step of setting a metal flange and a pair of electrode bodies in one of the forming dies; a step of filling the molding space with molten resin under pressure after closing the one and the other molding dies; a step of integrating the metal flange, the electrode bodies, and the resin sealing plate as the molten resin solidifies; and a step of opening the one and the other molds to release the sealing plate for a lithium battery.

6. 6. The method for manufacturing a sealing plate for a lithium battery according to claim 5, wherein the molding device has a structure in which a gate is disposed at a position spaced away from the outer electrodes of both electrode bodies set in the molding space toward the center of the molding space, and molten resin is pressure-filled through the gate.

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

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