Manufacturing method of secondary battery and the secondary battery

Abstract

To solve the problem in the related art that a production efficiency of a secondary battery is low.SOLUTION: A manufacturing method of a secondary battery according to the present invention includes a lower case molding step of resin-molding a lower case 20 having a housing part 21 for housing an electrode body 31 and an electrode terminal 10 connected to an electrode tab 32 of the electrode body 31, a tab welding step of welding the electrode tab 32 to the electrode terminal 10 from the housing part side in a state where the electrode body 31 is taken out from the housing part 21 of the lower case 20, an electrode body housing step of housing the electrode body 31 in the housing part 21 by bending the electrode tab 32 after the tab welding step, and a sealing step of adhering a lid 50 to an opening part of the lower case in a state where the electrode body 31 is housed in the housing part 21.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a secondary battery that houses an electrode assembly, for example, and the secondary battery. [Background technology]

[0002] In a secondary battery, an electrode assembly that stores and releases power is housed in a case. Patent Document 1 describes a technique for housing an electrode assembly in a case.

[0003] In the secondary battery described in Patent Document 1, the electrode plate assembly is housed in a conductive battery case. The electrode plate assembly is composed of positive and negative electrode plates wound with a separator sandwiched between them, and includes a positive electrode portion where the positive electrode plate protrudes from one end in a direction perpendicular to the winding direction, and a negative electrode portion where the negative electrode plate protrudes from the other end in the perpendicular direction. A resin film is disposed around the electrode plate assembly. The resin film is adhered to the portion (center) between the positive electrode portion and the negative electrode portion of the electrode plate assembly. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-162716 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the secondary battery described in Patent Document 1, a sub-assembly is assembled in which an external terminal and a current collecting member are joined to a lid, and the sub-assembly and the wound body are joined together before being housed in a case. In other words, when assembling the secondary battery described in Patent Document 1, there is a problem in that many steps are required for assembly, resulting in low production efficiency.

[0006] The present invention has been made in view of the above circumstances, and has as its object to improve the production efficiency of secondary batteries. [Means for solving the problem]

[0007] The method for manufacturing a secondary battery according to the present invention includes a lower case molding process in which a lower case having a storage section for storing an electrode body and an electrode terminal connected to an electrode tab of the electrode body is resin-molded; a tab welding process in which, with the electrode body removed from the storage section of the lower case, the electrode tab is welded to the electrode terminal from the storage section side; an electrode body storing process in which, after the tab welding process, the electrode tab is folded to store the electrode body in the storage section; and a sealing process in which a lid is adhered to the opening of the lower case with the electrode body stored in the storage section.

[0008] One aspect of the secondary battery of the present invention comprises an electrode body, a case in which the storage section in which the electrode body is stored is molded from resin, a lower case having electrode terminals insert-molded from the resin, and a lid that seals the lower case when the electrode body is stored in the storage section, and an electrode tab that is provided to protrude from the electrode body has its open end welded to the electrode terminal and is stored in a bent state. [Effects of the Invention]

[0009] According to the method for manufacturing a secondary battery and the secondary battery of the present invention, the number of parts required for electrically connecting the external terminals and the electrode body can be reduced, thereby improving production efficiency. [Brief explanation of the drawings]

[0010] [Figure 1] 2 is a schematic diagram illustrating a terminal component of a battery cell according to the first embodiment. FIG. [Figure 2] 4A to 4C are diagrams illustrating a lower case molding step according to the first embodiment. [Figure 3] 5A to 5C are diagrams illustrating a first example of a tab welding step and an electrode body housing step according to the first embodiment. [Figure 4] 10A to 10C are diagrams illustrating a second example of the tab welding step and the electrode body housing step according to the first embodiment. [Figure 5] FIG. 3 is a diagram illustrating a sealing step according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] For clarity of explanation, the following description and drawings have been omitted and simplified as appropriate. In each drawing, the same elements are denoted by the same reference numerals, and redundant explanations are omitted as necessary. In the following description, the direction in which the long sides of a battery cell extend is defined as the width direction X, the direction in which the short sides of the battery cell extend is defined as the thickness direction Z, and the direction perpendicular to the width direction X and the thickness direction Z, which corresponds to the height of the battery cell, is defined as the height direction Y. In the following description, the left-right direction relative to the width direction X may also be referred to as the left-right direction, and the up-down direction relative to the height direction Y. In the examples shown in the following description, a battery cell is assumed to have two electrode bodies arranged side by side in the width direction X of a single battery case.

[0012] Embodiment 1 The manufacturing method of the secondary battery according to the first embodiment includes a lower case molding step, a tab welding step, an electrode assembly housing step, and a sealing step. In the lower case molding step, a lower case having a housing portion for housing the electrode assembly and electrode terminals connected to the electrode tabs of the electrode assembly is resin-molded. In the following explanation, a secondary battery in which two electrode assemblies are housed in one case and two electrode assemblies connected in series form one battery cell will be described as an example, but the manufacturing method of the secondary battery according to the first embodiment can be applied to any secondary battery that houses one or more electrode assemblies in one case.

[0013] In the tab welding process, the electrode tab is welded to the electrode terminal from the housing side with the electrode body removed from the housing part of the lower case. In the electrode body storing process, which is performed after the tab welding process, the electrode tab is folded and stored in the housing part. In the sealing process, a lid is welded to the opening of the lower case with the electrode body stored in the housing part. In the following explanation, the lower case molding process, tab welding process, electrode body storing process, and sealing process will be described with reference to Figures 2 to 5.

[0014] In the battery cell 1 described in the first embodiment, the electrode terminals are insert-molded into the lower case. The electrode terminals will now be described in detail before they are insert-molded into the lower case. Figure 1 shows a schematic diagram illustrating the terminal components of the battery cell according to the first embodiment.

[0015] As shown in FIG. 1, the battery cell 1 according to the first embodiment has a first external terminal (e.g., an external positive electrode terminal 10) and a second external terminal (e.g., an external negative electrode terminal 12) as electrode terminals. The battery cell 1 according to the first embodiment also has an intermediate terminal 11 that electrically connects two electrode bodies housed in the lower case. A first electrode tab (e.g., a positive electrode tab) of the first electrode body is connected to the external positive electrode terminal 10. When the first electrode tab is a positive electrode, the external positive electrode terminal 10 is formed of a metal primarily composed of aluminum.

[0016] The intermediate terminal 11 electrically connects the second electrode tab (e.g., negative electrode) of the first electrode body and the first electrode tab (e.g., positive electrode) of the second electrode body. Specifically, the intermediate terminal 11 is formed by joining an intermediate negative electrode terminal 11a and an intermediate positive electrode terminal 11b. The intermediate negative electrode terminal 11a, to which the negative electrode tab of the electrode body is connected, is made of a metal primarily composed of copper, and the intermediate positive electrode terminal 11b, to which the positive electrode tab of the electrode body is connected, is made of a metal primarily composed of aluminum. The intermediate terminal 11 is formed by integrating the intermediate negative electrode terminal 11a and the intermediate positive electrode terminal 11b using a dissimilar material joining technique.

[0017] A second electrode tab (e.g., a negative electrode) of the second electrode body is connected to the external negative electrode terminal 12. When the second electrode tab is a negative electrode, the external negative electrode terminal 12 is formed from a metal containing copper as a main component.

[0018] In the manufacturing method of the secondary battery according to the first embodiment, the lower case is formed by insert molding in a state in which the external positive terminal 10, intermediate terminal 11, and external negative terminal 12 are aligned in the width direction X of the battery cell 1 in which the electrode bodies are arranged. Therefore, Fig. 2 shows a diagram illustrating the lower case molding process according to the first embodiment.

[0019] As shown in FIG. 2 , in the lower case molding process of the secondary battery according to the first embodiment, insert molding is performed to mold a lower case 20 with resin so that the external positive terminal 10, the intermediate terminal 11, and the external negative terminal 12 are enclosed in the resin. A first storage section 21 and a second storage section 22 are formed in the lower case 20. The external positive terminal 10, the intermediate terminal 11, and the external negative terminal 12 are arranged in a terminal arrangement surface of the lower case 20 that extends in a direction in which the first storage section and the second storage section 22 are adjacent to each other, such that the intermediate terminal 11 is sandwiched between the external positive terminal 10 and the external negative terminal 12. Here, the terminal arrangement surface is the surface surrounded by the first and second sides of the lower case 20, where the longest side is defined as the first side and the shortest side is defined as the second side. In the example of FIG. 2, the first side is a side extending in the width direction X, and the second side is a side extending in the thickness direction Z.

[0020] The lower case 20 is formed so that the surfaces of the external positive terminal 10 and the external negative terminal 12 that face the outside of the lower case 20 and the back surfaces that face the first storage section 21 and the second storage section 22 are both exposed. The intermediate terminal 11 is formed so that the surfaces of the intermediate negative terminal 11a and the intermediate positive terminal 11b that face the outside of the lower case 20 and the back surfaces that face the first storage section 21 and the second storage section 22 are both exposed. However, as shown in FIG. 2 , the lower case 20 is formed so that the portion of the intermediate terminal 11 where the intermediate negative terminal 11a and the intermediate positive terminal 11b are joined is covered with resin.

[0021] By covering the joint surfaces of the intermediate negative electrode terminal 11a and the intermediate positive electrode terminal 11b with resin in this manner, the joint surfaces are not exposed to air, and therefore corrosion of the joint surfaces can be prevented.

[0022] As shown in FIG. 2 , the first storage section 21 stores a first electrode body 31, and the second storage section 22 stores a second electrode body 34. In this storage state according to the first embodiment, the positive electrode tab 32 of the first electrode body 31 is joined to the external positive electrode terminal 10. The negative electrode tab 33 of the first electrode body 31 is joined to the intermediate negative electrode terminal 11a. In addition, in the storage state, the positive electrode tab 35 of the second electrode body 34 is joined to the intermediate positive electrode terminal 11b. The negative electrode tab 36 of the second electrode body 34 is joined to the external negative electrode terminal 12.

[0023] 2, a smoke exhaust port 23 is formed in the first storage section 21, and a smoke exhaust port 24 is formed in the second storage section 22. The smoke exhaust ports 23, 24 are provided on the surface (hereinafter referred to as the case bottom) opposite the surface on which the external positive terminal 10, intermediate terminal 11, and external negative terminal 12 are provided. The smoke exhaust ports 23, 24 are T-shaped and have a height such that the surface with the larger upper area contacts the surface (hereinafter referred to as the electrode body bottom) opposite the surface on which the electrode tabs of the first electrode body 31 and the second electrode body 34 are formed. With these smoke exhaust ports 23, 24, the bottom surface of the electrode body in a stored state in the battery cell 1 is supported by the member on which the smoke exhaust port is formed.

[0024] The smoke exhaust ports 23, 24 are provided with holes that penetrate through members formed in a shape that supports the first electrode body 31 and the second electrode body 34. The holes are provided with relief valves (not shown) that release gas from the storage compartment to the outside if the internal pressure of each compartment increases. The battery cell 1 is designed with these relief valves to prevent the internal pressure of the storage compartment from increasing above a certain level.

[0025] As shown in FIG. 2 , the electrode tabs include positive electrode tabs (e.g., positive electrode tab 32, positive electrode tab 35) and negative electrode tabs (e.g., negative electrode tab 33, negative electrode tab 36), and the positive electrode tabs and negative electrode tabs are provided so as to protrude from one side surface of the electrode assembly. In the manufacturing method for the secondary battery according to the first embodiment, after the tab welding step, the electrode assembly housing step is performed to house the electrode assembly in a housing section. Therefore, FIG. 3 shows a diagram illustrating a first example of the tab welding step and the electrode assembly housing step according to the first embodiment, and FIG. 4 shows a diagram illustrating a second example of the tab welding step and the electrode assembly housing step according to the first embodiment. Note that while FIGS. 3 and 4 show a portion of a cross section extending in the height direction Y including the external positive electrode terminal 10, the same tab welding step is also performed on the intermediate terminal 11 and the external negative electrode terminal 12.

[0026] In the first example shown in FIG. 3 , the first electrode body 31 is arranged so as to be parallel to the side surface of the lower case 20 (for example, a surface extending along the height direction Y and contacting the side surface of the electrode body stored in the storage section that has the largest area), and the positive electrode tab 32 is bent so as to contact the surface of the external positive electrode terminal 10 on the first storage section 21 side. Then, a horn HO, which is a tool for performing ultrasonic bonding, is pressed against the positive electrode tab 32 from the first storage section 21 side so as to press the positive electrode tab 32 against the external positive electrode terminal 10. Although not shown in the drawings, when performing ultrasonic bonding, an anvil (receiving jig) is pressed against the external positive electrode terminal 10 from the direction opposite to the horn HO.

[0027] 4, the first electrode body 31 is arranged so as to be perpendicular to the side surface of the lower case 20, and the positive electrode tab 32 is arranged so as to contact the surface of the external positive electrode terminal 10 on the first housing portion 21 side. Then, the horn HO is pressed against the positive electrode tab 32 from the first housing portion 21 side so as to press the positive electrode tab 32 against the external positive electrode terminal 10.

[0028] In this way, when the positive electrode tab 32 is placed on the external positive electrode terminal 10, a large space can be secured above the positive electrode tab 32. That is, in the manufacturing method for a secondary battery according to the first embodiment, a large space (e.g., tooling space) for inserting a tool such as a horn HO can be secured, thereby achieving high workability.

[0029] After the joining of the external positive electrode terminal 10 and the positive electrode tab 32 is completed, the electrode body storing step is carried out in both the first example shown in Fig. 3 and the second example shown in Fig. 4. In this electrode body storing step, the positive electrode tab 32 is stored in the first storage section 21 by rotating the first electrode body 31 around the joint portion between the external positive electrode terminal 10 and the positive electrode tab 32.

[0030] In this manner, by storing the first electrode body 31 in the first storage section 21 while rotating it with the positive electrode tab 32 joined to the external positive electrode terminal 10, the manufacturing method of the battery according to the first embodiment makes it possible to reduce the number of parts required to electrically connect the first electrode body 31 and the external positive electrode terminal 10, thereby reducing the number of assembly steps.

[0031] Next, Fig. 5 illustrates a sealing process according to the first embodiment. Fig. 5 illustrates the state in which the insulating cover 40 and the lid 50 are attached to the lower case 20, which houses the first electrode body 31 and the second electrode body 34 described in Fig. 2 in their respective housing sections. In the battery cell 1 according to the first embodiment, after housing the first electrode body 31 and the second electrode body 34 in their respective housing sections and carrying out a liquid injection process in which electrolyte is injected into each housing section to impregnate each electrode body with the electrolyte, the lid 50 is attached to the lower case 20 so as to cover the first housing section 21 and the second housing section 22. The lid 50 is attached to the lower case 20 so as to cover the surface with the largest area. Furthermore, the insulating cover 40 is fitted over the exposed portions of the intermediate negative electrode terminal 11a and the intermediate positive electrode terminal 11b.

[0032] At least the surface of the insulating cover 40 is formed from an insulating material. As an example, the insulating cover 40 is formed from an insulating material such as aluminum nitride. The insulating cover 40 has a shape that contacts the intermediate negative electrode terminal 11a and the intermediate positive electrode terminal 11b that are exposed to the outside after the resin is formed. Here, the insulating cover 40 preferably has a higher thermal conductivity than the resin that constitutes the lower case 20. By forming the insulating cover 40 from a material with such high thermal conductivity, the insulating cover 40 can function as a heat dissipation component that promotes the release of heat generated in the battery cells 1. In other words, by using a material with high insulating properties and heat dissipation properties for the insulating cover 40, it is possible to provide the insulating cover 40 with both insulating and heat dissipation functions.

[0033] 5 shows an example in which one lid 50 is provided for two storage sections, but a separate lid 50 may be prepared for each storage section. By providing a lid for each storage section in this way, it is possible to obtain effects such as making it easier to weld the lids and making it possible to adjust the pressure applied to each electrode body by changing the shape of the lid in accordance with variations in each electrode body.

[0034] The secondary battery manufactured through the processes described with reference to Figures 2 to 5 comprises the first electrode body 31 and the second electrode body 34, a case in which the storage section for storing the first electrode body 31 and the second electrode body 34 is molded from resin, a lower case 20 having electrode terminals insert-molded from resin, and a lid 50 that seals the lower case when the first electrode body 31 and the second electrode body 34 are stored in the storage section, and the electrode tabs that are provided so as to protrude from the first electrode body 31 and the second electrode body 34 have their open ends welded to electrode terminals (for example, the external positive electrode terminal 10, the intermediate terminal 11, and the external negative electrode terminal 12) and are stored in a bent state.

[0035] As described above, in the manufacturing method for the secondary battery according to the first embodiment, the external positive terminal 10 and the external negative terminal 12, which serve as external terminals, and the intermediate terminal 11, which electrically connects the two electrode assemblies, are each integrally molded as a plate-like member. Furthermore, in the manufacturing method for the secondary battery according to the first embodiment, the external positive terminal 10, the intermediate terminal 11, and the external negative terminal 12 are integrated with the lower case 20 by insert molding. In the manufacturing method for the secondary battery according to the first embodiment, electrode tabs of the electrode assembly are joined to the external positive terminal 10, the intermediate terminal 11, and the external negative terminal 12, which are exposed on the housing side of the lower case 20, and the electrode assembly is stored in the housing by rotating the electrode assembly around the joint. By storing the electrode assembly in the housing of the lower case through these steps, the external terminals are essentially the only members electrically connecting the electrode assembly and the external terminals, thereby reducing the number of parts. Furthermore, reducing the number of parts enables a reduction in the number of manufacturing steps for the secondary battery.

[0036] Furthermore, in the manufacturing method of the secondary battery according to the first embodiment, when joining the electrode tab to the external terminal, it is possible to ensure a large tooling space above the part to be joined, which makes it easy to insert a horn HO or the like used for joining, and makes it easier to design the process.

[0037] The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit and scope of the invention. For example, in the above description, the first external terminal is the negative terminal and the second body terminal is the positive terminal, but it is easily conceivable to reverse this. [Explanation of symbols]

[0038] 1 battery cell 10 External positive terminal 11 Intermediate terminal 11a Intermediate negative terminal 11b Intermediate positive terminal 12 External negative terminal 20 Lower Case 21 First storage compartment 22 Second storage area 23 Smoke exhaust vent 24 Smoke exhaust vent 31 First electrode body 32 Positive electrode tab 33 Negative electrode tab 34 Second electrode body 35 Positive electrode tab 36 Negative electrode tab 40 Insulating cover 50 lids

Claims

1. a lower case molding step of resin-molding a lower case having a housing portion for housing an electrode body and electrode terminals connected to electrode tabs of the electrode body; a tab welding step of welding the electrode tab to the electrode terminal from the housing portion side while the electrode body is removed from the housing portion of the lower case; an electrode body storing step of storing the electrode body in the storing section by bending the electrode tab after the tab welding step; a sealing step of adhering a lid to the opening of the lower case with the electrode body housed in the housing; A method for manufacturing a secondary battery having the above structure.

2. The method for manufacturing a secondary battery according to claim 1 , further comprising a liquid injection step of impregnating the electrode body with an electrolyte between the electrode body housing step and the sealing step.

3. 2. The method for manufacturing a secondary battery according to claim 1, wherein the electrode tabs include a positive electrode tab and a negative electrode tab, and the positive electrode tab and the negative electrode tab are provided so as to protrude from one side surface of the electrode body.

4. The method for manufacturing a secondary battery according to claim 1 , wherein the electrode terminals are fixed in a state of being insert-molded with a resin that forms the lower case.

5. The electrode body includes a first electrode body and a second electrode body, the lower case has a first storage section that stores the first electrode body and a second storage section that stores the second electrode body, the electrode terminals include a first external terminal to which a first electrode tab of the first electrode body is welded, an intermediate terminal that electrically connects a second electrode tab of the first electrode body and a first electrode tab of the second electrode body, and a second external terminal to which a second electrode tab of the second electrode body is connected; 2. The method for manufacturing a secondary battery according to claim 1, wherein the first external terminal, the intermediate terminal, and the second external terminal are arranged on a terminal arrangement surface of the lower case that extends in a direction in which the first storage section and the second storage section are adjacent to each other, so that the intermediate terminal is sandwiched between the first external terminal and the second external terminal.

6. An electrode body; a case having a housing portion molded from resin in which the electrode body is housed, a lower case having electrode terminals insert-molded from the resin; a lid that seals the lower case when the electrode body is stored in the storage section, The secondary battery has an electrode tab provided so as to protrude from the electrode body, the open end of which is welded to the electrode terminal, and is stored in a bent state.

7. The secondary battery according to claim 6 , wherein the lid is adhered to the lower case so as to cover the surface of the lower case that has the largest area.

8. The electrode body includes a first electrode body and a second electrode body, the storage section has a first storage section that stores the first electrode body and a second storage section that stores the second electrode body, 7. The secondary battery according to claim 6, wherein the electrode terminals include a first external terminal to which a first electrode tab of the first electrode body is welded, an intermediate terminal that electrically connects a second electrode tab of the first electrode body and a first electrode tab of the second electrode body, and a second external terminal to which a second electrode tab of the second electrode body is connected.

9. 9. The secondary battery according to claim 8, wherein the first external terminal, the intermediate terminal, and the second external terminal are arranged on a terminal arrangement surface of the lower case that extends in a direction in which the first storage section and the second storage section are adjacent to each other, so that the intermediate terminal is sandwiched between the first external terminal and the second external terminal.

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