Method for manufacturing a battery cell

Abstract

This invention suppresses insufficient resin welding during the manufacturing of battery cells. In the manufacturing method of battery cell (1), electrode sheets (3, 4) are stacked in the stacking direction. The electrode sheets (3, 4) have electrodes (32, 42) located in the container (10) and current collectors (31, 41) connected to the electrodes in the container and protruding outward from the container opening (12, 13). The resin (51) located between the stacked current collectors is preheated by the current collectors. After the preheating begins, the resin is pressurized and heated from the outside to the center in the stacking direction at the container opening. Then, the resin is welded between the current collectors and the container opening is sealed.

Description

Technical Field

[0001] The technology disclosed herein relates to a method for manufacturing a single battery cell. Background Technology

[0002] Patent Document 1 describes a conventional laminated battery. A laminated battery is a battery in which an electrode body is housed within an outer casing. The laminated battery has a plurality of current collector terminals extending from the electrode body to the outer casing. These current collector terminals overlap with a thermoplastic resin. At the periphery of the outer casing, the resin is fused together and to the outer casing, thereby sealing the periphery of the outer casing from which the current collector terminals extend. In the laminated battery, each current collector terminal extends outward from the outer casing. Within the outer casing, the plurality of current collector terminals are not connected to each other. In the laminated battery, the space within the outer casing can be used to expand the electrode body. The structure of the laminated battery is advantageous for increasing the battery's energy density.

[0003] [Existing Technical Documents] [Patent Documents] [Patent Document 1] Japanese Patent Application Publication No. 2009-272161. Summary of the Invention

[0004] [The technical problem the invention aims to solve] The stacked battery is manufactured via a heat-sealing process. In the heat-sealing process, a heating plate, serving as the energy supply source, is pressed in the overlapping direction, thereby fusing the overlapping resins at the periphery of the outer casing together. In the stacked battery described in Patent Document 1, the number of current collector terminals extending outwards from the outer casing is small. The resin fusing during the heat-sealing process is relatively easy.

[0005] If the number of current collector terminals extending outwards from the external components increases, multiple layers of resin must be welded. If there are many layers of resin, the resin located on the central side in the stacking direction will be significantly further away from the energy supply source for welding. In the manufacturing process of stacked batteries with a large number of current collector terminals, there may not be sufficient energy supplied to the resin located on the central side, resulting in incomplete welding of the resin on the central side.

[0006] The technology disclosed herein is used to suppress insufficient resin welding during the manufacture of battery cells.

[0007] Technical means to solve technical problems The technology disclosed herein relates to a method for manufacturing a single battery cell. In this manufacturing method, Electrode sheets are stacked in a stacking direction. Each electrode sheet has an electrode located inside a container and a current collector connected to the electrode inside the container and protruding outward from the opening of the container. The resin located between the stacked current collectors is preheated by the current collector. After the preheating begins, pressure and heat are applied to the resin at the opening of the container from the outside to the center in the lamination direction. The resin is fused between the current collectors and the opening of the container is sealed.

[0008] In a battery cell manufactured using this method, a plurality of stacked current collectors protrude outwards through openings in the container. These current collectors are connected, for example, to electrodes of the same polarity. Inside the container, the current collectors are not connected to each other. This eliminates the need for connection spaces between the current collectors within the container. The electrodes of the battery cell can be expanded using the space inside the container. This structure allows for increased energy density in the battery cell.

[0009] The container opening is sealed with resin. The resin is, for example, a thermoplastic resin. During the manufacture of the battery cell, at the container opening, the stacked current collectors and the resin between them are pressurized and heated from the outside to the center in the stacking direction. Alternatively, a pair of heating plates located on the outside of the container can be used to sandwich multiple resins in the stacking direction, with the heating plates supplying heat to the resin from the outside to the center in the stacking direction. Heat is transferred sequentially from the resin on the outside to the resin on the center side in the stacking direction. Due to attenuation, the heat supplied to the resin on the center side in the stacking direction is tends to be lower than the heat supplied to the resin on the outside side in the stacking direction.

[0010] In the manufacturing method, the resin is preheated by a current collector before pressurization and heating begin. Heat is efficiently supplied to the resin located at the center of the lamination direction via a current collector positioned at the center of the lamination direction.

[0011] The combination of resin preheating via the current collector and pressurization and heating from the outside of the stacking direction ensures a sufficient supply of heat to both the resin located on the outside and the resin located on the center side of the stacking direction. Therefore, during the manufacture of the battery cell, all resin is fused along the entire stacking direction. This prevents variations in the sealing strength of the container opening due to differences in location.

[0012] Furthermore, if the resin is not preheated via a current collector, the heat supplied from the outer side of the lamination direction needs to be continuously pressurized and heated for a relatively long time to fully reach the resin on the central side of the lamination direction. Prolonged pressurization and heating time may lead to an oversupply of heat to the resin on the outer side of the lamination direction.

[0013] Preheating via the current collector shortens the time from the start of pressurization and heating from the outside of the stacking direction to the point where sufficient heat energy is supplied to the resin in the center of the stacking direction. Shortening the pressurization and heating time ensures sufficient heat energy is supplied to the resin in the center of the stacking direction and prevents excessive heat energy from being supplied to the resin on the outside of the stacking direction. This allows for a stable seal of the container opening. The reduced pressurization and heating time also improves the manufacturing efficiency of the battery cells. Current collectors generally have high thermal conductivity. After preheating begins, the resin is rapidly heated through the current collector. The time difference between starting preheating via the current collector and starting pressurization and heating from the outside of the stacking direction can be minimal.

[0014] Resin preheating via a current collector can also be performed on a portion of a plurality of resins stacked in the lamination direction. For example, the resin located at the center of the lamination direction can be preheated by a current collector. This is because the heat energy supplied to the resin located at the center of the lamination direction is relatively low.

[0015] Alternatively, the preheating performed by the current collector can continue even after the pressurization and heating of the resin begins.

[0016] If preheating via the current collector is stopped during resin pressurization and heating, heat loss through the current collector may cause the resin temperature to drop. By continuing preheating via the current collector even after resin pressurization and heating have begun, heat loss through the current collector can be suppressed. With continuous preheating, all resin is fused, stably sealing the container opening.

[0017] Alternatively, the preheating performed by the current collector may end before or together with the end of resin heating.

[0018] If preheating continues through the current collector after the resin heating process has ended, the resin temperature may become too high. Preheating through the current collector should end before or at the same time as the resin heating process to prevent excessive resin temperature rise.

[0019] Alternatively, the resin pressurization and resin heating can be completed together, or the process can be completed after the resin heating is finished.

[0020] Resin heating is not continued after pressurization, thus preventing excessive heat supply to the resin. Appropriate heat supply to the resin, coupled with sufficient pressurization, ensures a proper seal of the container opening. Resin pressurization can also continue after resin heating is complete. Continuous pressurization allows for stable resin welding. Continuous pressurization improves the sealing quality of the container opening.

[0021] Alternatively, the preheating by the current collector can be performed by the first heating plate, and the pressurization and heating of the resin can be performed by the second heating plate, which is different from the first heating plate.

[0022] Using two heating plates, a first heating plate and a second heating plate, allows for separate temperature settings for the first and second heating plates. It also allows for separate setting of the start and end times of heating for the first and second heating plates. This ensures proper welding of the stacked resin layers, improving the sealing quality of the container opening.

[0023] Alternatively, the first heating plate can be heated such that a plurality of the current collectors overlap in the stacking direction.

[0024] Heating multiple current collectors together using the first heating plate can properly preheat the stacked multiple resins individually.

[0025] [Invention Effects] The method for manufacturing the battery cell can suppress insufficient resin welding during the manufacturing process. Attached Figure Description

[0026] Figure 1 It is a cross-sectional view of a single battery cell; Figure 2 The illustration shows a part of the manufacturing process of a single battery cell; Figure 3 The illustration shows a part of the manufacturing process of a single battery cell; Figure 4 The illustration shows a part of the manufacturing process of a single battery cell; Figure 5 The illustration shows a part of the manufacturing process for a single battery cell. Detailed Implementation

[0027] The following describes an implementation of the battery cell manufacturing process with reference to the accompanying drawings. The battery cell manufacturing process described here is an example.

[0028] (Structure of a single battery cell) Figure 1 The diagram schematically illustrates the overall structure of battery cell 1. Battery cell 1 is a secondary battery. Battery cell 1 is, for example, a lithium-ion battery.

[0029] The battery cell 1 is a so-called pouch-type battery. The battery cell 1 includes a power generation element 2 and a container 10. The container 10 is sealed while housing the power generation element 2 and electrolyte. The container 10 is a pouch-shaped object formed by folding one sheet of laminated material 11 or overlapping two sheets of laminated material 11. The laminated material 11 is, for example, a three-layer structure with a metal layer sandwiched between resin layers. The metal layer is, for example, aluminum or stainless steel. The resin layer is, for example, polypropylene (PP) or polyethylene (PE).

[0030] The power generation element 2 has a first electrode sheet 3. The first electrode sheet 3 is, for example, a negative electrode sheet. The power generation element 2 has a second electrode sheet 4. The second electrode sheet 4 is, for example, a positive electrode sheet. The first electrode sheet 3 and the second electrode sheet 4 overlap each other. The number of first electrode sheets 3 and second electrode sheets 4 in the power generation element 2 is arbitrary. The power generation element 2 is an electrode laminate. Hereinafter, the direction in which the first electrode sheet 3 and the second electrode sheet 4 are laminated is sometimes referred to as the lamination direction. The lamination direction is... Figure 1 And then... Figures 2-5 The top and bottom directions of the paper.

[0031] The first electrode 3 has a current collector body 31. The current collector body 31 is a thin sheet or foil extending in a direction orthogonal to the lamination direction. The end of the current collector body 31, i.e. Figure 1 The left end of the container protrudes out of the container 10 from the first opening 12 of the container 10.

[0032] An active material is coated onto the first and second surfaces of the current collector 31 located inside the container 10. The first surface... Figure 1 The middle is the upper surface of the current collector 31, and the second surface is... Figure 1 The lower surface of the current collector 31 is in the middle. The active material forms the first electrode 32. The current collector 31 is connected to the first electrode 32 inside the container 10.

[0033] The first electrode 3 has a diaphragm 33. The diaphragm 33 separates the first electrode 32 of the first electrode 3 from the second electrode 42 of the second electrode 4 (described later). The diaphragm 33 is, for example, a porous material that is permeable to ionic materials.

[0034] A diaphragm 33 covers the respective surfaces of the two first electrodes 32 in the first electrode sheet 3. The diaphragm 33 can be formed by attaching a membrane to the first electrode 32. Alternatively, it can be formed by drying the suspension coated on the first electrode 32. The area of ​​the diaphragm 33 can be the same as or larger than the area of ​​the first electrode sheet 3.

[0035] The second electrode plate 4 has a current collector 41. The current collector 41 is a thin plate or foil extending in a direction orthogonal to the lamination direction. The end of the current collector 41, i.e. Figure 1 The right end of the current collector 41 protrudes outward from the second opening 13 of the container 10. In a direction orthogonal to the stacking direction, the second opening 13 is the opposite of the first opening 12. The protruding direction of the current collector 41 is not limited to the opposite direction of the protruding direction of the current collector 31.

[0036] An active material is coated onto the first and second surfaces of the current collector 41 located inside the container 10. The active material forms the second electrode 42. The current collector 41 is connected to the second electrode 42 inside the container 10.

[0037] As previously described, the first electrode sheet 3 and the second electrode sheet 4 are stacked alternately. The first electrode 32 and the second electrode 42 are stacked in the stacking direction inside the container 10 via a diaphragm 33.

[0038] The first opening 12 of container 10 is sealed with resin 5. Resin 5 is a sealing material. Resin 5 is located between the laminated material 11 and the current collector 31, and between each current collector 31. Similarly, the second opening 13 is sealed with resin 5. Resin 5 is located between the laminated material 11 and the current collector 41, and between each current collector 41.

[0039] A plurality of current collectors 31 are not connected inside the container 10 and protrude outward from the container 10. Similarly, a plurality of current collectors 41 are not connected inside the container 10 and protrude outward from the container 10. The connection space for the current collectors 31 and 41 can be omitted inside the container 10, thus allowing for a corresponding increase in the area of ​​the first electrode 32 and the second electrode 42. This improves the energy density of the battery cell 1.

[0040] (Manufacturing method of battery cell) Next, refer to Figure 2 , 3 Sections 4 and 5 describe the manufacturing method of battery cell 1. The manufacturing method of battery cell 1 is as follows: Figure 2 , 3 The process is carried out in the order of 4 and 5. Here, the manufacturing method of the battery cell 1 will be explained using the welding of resin in the first opening 12 as an example. The welding of resin in the second opening 13 is the same.

[0041] First, prepare the first electrode plate 3 and the second electrode plate 4. As mentioned earlier, the first electrode plate 3 has a current collector 31, a first electrode 32, and a diaphragm 33. The first electrode plate 3 also has a resin 51 (see reference). Figure 2 The resin 51 is located between the end of the current collector 31 and the first electrode 32 in the current collector 31. The resin 51 is pre-fused to the first surface and the second surface of the current collector 31, respectively.

[0042] The second electrode 4 has a current collector 41, a second electrode 42, and resin. The resin of the second electrode 4, like the resin 51 of the first electrode 3, is located in the current collector 41 between the end of the current collector 41 and the second electrode 42. The resin is pre-fused to the first and second surfaces of the current collector 41, respectively.

[0043] Next, as Figure 2 As shown, the first electrode plate 3 and the second electrode plate 4 are stacked alternately. Figure 3 As shown, the first electrode 32 and the second electrode 42 are overlapped by a diaphragm 33. Resin 51 is located between the current collectors 31 of the first electrode 3. The resin 51 is arranged in the stacking direction. Resin is also located between the current collectors 41 of the second electrode 4.

[0044] Resin 51 is a thermoplastic resin. Resin 51 is selected from cast polypropylene (CPP), low-density polyethylene (LDPE), linear low-density polyethylene (LDPE), high-density polyethylene (HDPE), oriented polypropylene (OPP), polyethylene terephthalate (PET), or biaxially oriented nylon (ONY).

[0045] After the first electrode sheet 3 and the second electrode sheet 4 are stacked to form the power generation element 2, the stacked material 11 covers the power generation element 2. For example... Figure 3 As shown, the edge of the laminated material 11 ( Figure 3 The position of the left edge (in the middle) corresponds to the position of the resin 51. In the stacking direction, the stacked material 11 is located on the outside relative to the outermost current collector 31. That is, in Figure 3 In the vertical direction, the stacked material 11 is located above the uppermost current collector 31 and below the lowermost current collector 31.

[0046] Next, the resin 51 is preheated. Preheating of the resin 51 is performed using a pair of first heating plates 61, 61. The pair of first heating plates 61, 61 sandwich a plurality of current collectors 31 in the stacking direction at the ends of the current collectors 31. The plurality of current collectors 31 overlap in the stacking direction. The high-temperature first heating plates 61, 61 heat the resin 51 while the plurality of current collectors 31 overlap in the stacking direction. Figure 3 As indicated by the hollow arrow, heat energy is supplied from the pair of first heating plates 61, 61 to resin 51 through current collector 31. Figure 3 In the diagram, only the current collector 31 at the center of the stacking direction is shown with an arrow, but heat energy is supplied to the resin 51 connected to the current collector 31 through each current collector 31. Each resin 51 heats up.

[0047] After the preheating of resin 51 begins, as follows Figure 4 As shown, the resin 51 arranged in the lamination direction is welded using a heating plate. The welding is performed using a pair of second heating plates 62, 62. The pair of second heating plates 62, 62 are located on the outer side of the laminated material 11, and apply pressure to the resin 51 arranged in the lamination direction from the outer side towards the center (see reference). Figure 4 (The gray arrow indicates the location of the first heating plate 61), and the resin 51 arranged in the stacking direction is heated. After the welding of the second heating plate 62, 62 begins, the preheating of the first heating plate 61, 61 continues.

[0048] The heat energy from the high-temperature second heating plates 62 is transferred from the outer side to the central side in the lamination direction through the laminated material 11, resin 51, and current collector 31. The resin 51 receives the heat energy and melts.

[0049] Here, as Figure 4 As indicated by the hollow arrow, due to attenuation, the heat energy supplied from the second heating plates 62, 62 to the resin 51 located at the center of the lamination direction is tends to be lower than the heat energy supplied to the resin 51 located at the outer side of the lamination direction. This may result in insufficient welding of the resin 51 located at the center of the lamination direction.

[0050] In this regard, the resin 51 located at the center of the lamination direction is preheated by the current collector 31. The resin 51 located at the center of the lamination direction is heated by the current collector 31, and heat energy is also supplied from the second heating plate 62 in the lamination direction. Sufficient heat energy is supplied to the resin 51 located at the center of the lamination direction.

[0051] In this way, sufficient heat energy is supplied to both the resin 51 located on the outer side of the lamination direction and the resin 51 located on the central side of the lamination direction. Figure 5 As shown, at the opening of container 10 (here, the first opening 12), the laminated material 11 and the current collector 31 are sealed by the fused resin 5, as well as between each current collector 31.

[0052] After the resin 51 is welded, the pressure and heating of the second heating plates 62 and 62 are completed, and the heating of the first heating plates 61 and 61 is completed. If the first heating plates 61 and 61 separate from the current collector 31, sometimes the current collectors 31 will separate from each other in the stacking direction.

[0053] In the aforementioned manufacturing method, before starting the heating plate welding using the second heating plates 62, 62, the resin 51 is preheated using the first heating plates 61, 61. Sufficient heat is supplied to both the resin 51 located at the center side in the lamination direction and the resin 51 located at the outer side in the lamination direction.

[0054] Furthermore, if the resin 51 is preheated by the current collector 31 before the heating plate is welded, the time from the start of pressurization and heating from the outside of the lamination direction to the supply of sufficient heat energy to the resin 51 in the center of the lamination direction can be shortened. This can suppress the excessive supply of heat energy to the resin 51 on the outside of the lamination direction.

[0055] According to this manufacturing method, the variation in sealing strength of the openings 12 and 13 of the container 10 depending on the location is suppressed. All resins 51 can be stably fused, thus improving the sealing quality of the openings 12 and 13 of the container 10.

[0056] The current collector 31 has high thermal conductivity, so the resin 51 is rapidly heated through the current collector 31 after preheating begins. The heating plate welding can also begin rapidly after preheating through the current collector 31. Even if preheating through the current collector 31 begins beforehand, the manufacturing time does not increase, and the heating plate welding time is shortened, thus improving the manufacturing efficiency of the battery cell.

[0057] Furthermore, in the aforementioned manufacturing method, the preheating of the first heating plates 61, 61 via the current collector 31 continues even after the welding of the second heating plates 62, 62 begins. During the welding of the second heating plates 62, 62, heat dissipation generated through the current collector 31 is suppressed. This suppresses the temperature drop of the resin 51 due to heat dissipation, thus enabling stable welding of the resin 51.

[0058] Furthermore, the preheating of the first heating plates 61, 61 via the current collector 31 ends simultaneously with the completion of the welding of the heating plates using the second heating plates 62, 62. If preheating continues via the current collector 31 after the welding of the heating plates has ended, it may result in excessive heat supply to the resin 51. By ending the preheating via the current collector 31 simultaneously with the completion of the welding of the heating plates, excessive heat supply to the resin 51 can be prevented.

[0059] The preheating of the first heating plates 61, 61 through the current collector 31 can also be completed before the welding of the heating plates 62, 62 is finished.

[0060] Furthermore, by using both a first heating plate 61 and a second heating plate 62, the temperatures of the first heating plate 61 and the second heating plate 62 can be set independently. The start and end times of heating for the first heating plate 61 and the second heating plate 62 can also be set independently. In this manufacturing method, the preheating of the resin 51 using the first heating plate 61 and the welding of the resin 51 using the second heating plate 62 can be controlled independently. This independent control of preheating and welding improves the sealing quality of the openings 12 and 13 of the container 10.

[0061] Furthermore, the first heating plates 61, 61 are heated while the plurality of current collectors 31 are stacked in the stacking direction, so the plurality of current collectors 31 are heated together. The plurality of stacked resins 51 can be preheated separately, and heat dissipation generated from the plurality of current collectors 31 during the welding of the heating plates can be suppressed, so the plurality of resins 51 can be properly welded separately.

[0062] (Modified example) The first heating plates 61, 61 can also selectively heat the current collectors 31, 41 located on the central side of the stacking direction, for example.

[0063] Furthermore, regarding the termination of the welding of the second heating plate 62, if the pressure termination and heating termination of the second heating plate 62 can be set independently, the second heating plate 62 can continue to apply pressure even after heating is completed. By continuously applying pressure, the resin 51 can be properly welded, improving the sealing quality of the openings 12 and 13 of the container 10.

[0064] In addition to heating plate welding using the second heating plate 62, energy can also be supplied to the resin 51 from the outer side towards the center side in the lamination direction, for example, by vibration welding, ultrasonic welding, or high-frequency welding, thereby welding the resin 51. In various welding methods, even if there is energy attenuation during welding, in the manufacturing method described above, by combining resin preheating through current collectors 31 and 41, welding of the resin 51 located on the center side in the lamination direction can be sufficiently achieved.

[0065] Preheating via current collectors 31 and 41 and welding of the heating plate can also be performed using the same heating plate.

[0066] Preheating via current collectors 31 and 41 can also be completed at the start of or before the start of welding on the heating plate.

[0067] [Numbering Explanation] 1. Battery cell 10 containers 12 First opening 13 Second opening 3. Electrode 1 31 Current collector 32 First Electrode 4. Second electrode plate 41 Current collector 42 Second electrode 5. Resin 51 Resin 61 First heating plate 62 Second heating plate

Claims

1. A method for manufacturing a single battery cell, wherein: Electrode sheets are stacked in a stacking direction, the electrode sheets having electrodes located inside a container and current collectors connected to the electrodes inside the container and protruding outward from the opening of the container; The resin located between the stacked current collectors is preheated by the current collector; After the preheating begins, pressure and heat are applied to the resin at the opening of the container from the outside to the center in the lamination direction. The resin is fused between the current collectors and the opening of the container is sealed.

2. The method for manufacturing a single battery cell according to claim 1, characterized in that: Preheating via the current collector continues after the pressurization and heating of the resin begins.

3. The method for manufacturing a single battery cell according to claim 2, characterized in that: Preheating via the current collector ends either before or together with the end of resin heating.

4. The method for manufacturing a single battery cell according to claim 3, characterized in that: The pressurization of the resin ends at the same time as the heating of the resin, or it ends after the heating of the resin has ended.

5. The method for manufacturing a single battery cell according to claim 1, characterized in that: Preheating via the current collector is performed through the first heating plate. The resin is pressurized and heated by a second heating plate, which is different from the first heating plate.

6. The method for manufacturing a single battery cell according to claim 5, characterized in that: The first heating plate is heated such that a plurality of the current collectors overlap in the stacking direction.

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