Method for manufacturing a battery

Abstract

This invention provides a method for manufacturing a storage battery that can improve the assemblability of the storage battery. A method for manufacturing a storage battery (1) wherein the storage battery (1) has a plurality of buffers (11) stacked and a plurality of individual cells (10) respectively disposed between two adjacent buffers (11), the method for manufacturing the storage battery repeatedly pressurizes and depressurizes the stack (12) of the plurality of individual cells (10) and the plurality of buffers (11) in the stacking direction according to the posture change of the stack (12) relative to the stacking direction, and compresses the stack (12) at the same time.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a storage battery. Background Technology

[0002] In recent years, research and development related to secondary batteries that help improve energy efficiency has been ongoing in order to ensure that more people have access to suitable, reliable, sustainable and advanced energy.

[0003] In the battery pack manufacturing method described in Patent Document 1, a stack of multiple individual cells is pressurized with a first pressure for a certain period of time, and then the stack is pressurized with a second pressure that is lower than the first pressure, while the stack is constrained by a constraint member.

[0004] In the method for manufacturing an energy storage module described in Patent Document 2, a first pressurization step is performed to compress a stack of multiple energy storage units, the pressure is released and the positions of each unit of the stack are aligned, and then a second pressurization step is performed to compress the stack again, thereby constraining the stack under the applied pressure.

[0005] In the battery module manufacturing method described in Patent Document 3, a portion of the battery stack is disposed between one end plate and the middle plate, the gap between the end plate and the middle plate is reduced, and the battery stack disposed between them is compressed. Then, the remaining battery stack is disposed between the other end plate and the middle plate.

[0006] In the battery pack manufacturing method described in Patent Document 4, all the individual cells constituting the battery pack are divided into two groups. In each group, multiple individual cells are stacked by sandwiching spacers between two adjacent individual cells, and the stack of individual cells and spacers is compressed.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent No. 7420783

[0010] Patent Document 2: Japanese Patent No. 7307106

[0011] Patent Document 3: Japanese Patent No. 7070381

[0012] Patent Document 4: Japanese Patent Application Publication No. 2023-116062 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] For example, in batteries used in electric vehicles such as electric cars, the number of stacked individual cells tends to increase due to requirements for larger capacity and / or higher voltage. The more numerous the individual cells, the more prone the cells and buffers in the middle of the stacked structure are to positional shift perpendicular to the stacking direction when compressed, both in the stacked cell and buffer components. For instance, in the method for manufacturing an energy storage module described in Patent Document 2, the pressure is released during the first and second pressurization steps to align the cells that have caused the positional shift.

[0015] One of the objectives of this invention is to improve the assemblability of batteries.

[0016] Methods for solving problems

[0017] One technical solution of the present invention is a method for manufacturing a storage battery, wherein the storage battery comprises multiple buffer components stacked together and multiple single cells respectively disposed between two adjacent buffer components, wherein,

[0018] The battery manufacturing method involves repeatedly pressurizing and depressurizing the stacked body of the plurality of individual cells and the plurality of buffer components in the stacking direction according to the posture changes of the stacked body relative to the stacking direction, while simultaneously compressing the stacked body.

[0019] Invention Effects

[0020] According to the present invention, the assemblability of the storage battery can be improved. Attached Figure Description

[0021] Figure 1 This is a schematic front view illustrating an example of a storage battery used to explain an embodiment of the present invention.

[0022] Figure 2 It is represented in sequence Figure 1 A diagram illustrating an example of a method for manufacturing a storage battery.

[0023] Figure 3 It is represented in sequence Figure 1 A diagram illustrating an example of a method for manufacturing a storage battery.

[0024] Figure 4 yes Figure 2 and Figure 3 A flowchart of the compression process of the laminate in the manufacturing method of a storage battery.

[0025] Figure 5 It is a schematic representation Figure 4 A diagram of the compression process.

[0026] Figure 6 It is a schematic representation Figure 4 A diagram of the compression process.

[0027] Figure 7 It is a schematic representation Figure 4 A diagram of the compression process.

[0028] Figure 8 It means Figure 1 A diagram illustrating another example of a method for manufacturing a storage battery.

[0029] Figure 9 It means Figure 1 A cross-sectional view of an example of a battery buffer.

[0030] Explanation of reference numerals in the attached figures

[0031] 1. Storage battery

[0032] 3 end plates

[0033] 4 Framework

[0034] 10 single cells

[0035] 11. Buffer

[0036] 12-layer stack

[0037] 20 First Surface Pressure Sensor

[0038] 21 Second surface pressure sensor. Detailed Implementation

[0039] An example of a storage battery and its manufacturing method for illustrating embodiments of the present invention will be described based on the accompanying drawings.

[0040] Figure 1 The battery 1 shown includes multiple individual cells 10 and multiple buffers 11. The individual cells 10 and buffers 11 are flat or planar and are stacked in the thickness direction. The individual cells 10 are sandwiched between two adjacent buffers 11. The battery 1 also includes a set of end plates 3 of the stacked body 12 that sandwiches the multiple individual cells 10 and multiple buffers 11 in the stacking direction, and a frame 4 that constrains the set of end plates 3 to each other. The frame 4 fixes the spacing of the set of end plates 3.

[0041] In addition, battery 1 is equipped with more than one surface pressure sensor. Figure 1In the example shown, the battery 1 includes two surface pressure sensors: a first surface pressure sensor 20 and a second surface pressure sensor 21. The first surface pressure sensor 20 is disposed at the center of the laminate 12 in the stacking direction, and the second surface pressure sensor 21 is disposed at one end of the laminate 12 in the stacking direction. The first surface pressure sensor 20 and the second surface pressure sensor 21 acquire the in-plane pressure distribution in the direction intersecting the stacking direction. Furthermore, the number of surface pressure sensors disposed on the laminate 12 can be one or more than three. The location of the surface pressure sensors is not limited to one end or the center of the laminate 12 in the stacking direction; however, considering the potential for displacement of the single battery 10 and the buffer member 11 in the middle of the stacking direction, it is preferable to provide them at least in the center.

[0042] A single cell 10 is a so-called laminated single cell, in which the positive electrode, negative electrode, spacer, and electrolyte are sealed in a laminated film. Generally, compared with canned single cells where materials such as the positive electrode are sealed in a cylindrical or square metal container, laminated single cells have a higher energy density per unit volume and excellent heat dissipation.

[0043] The single cell 10 can be a lithium-ion battery or a nickel-metal hydride battery using a liquid electrolyte, or it can be an all-solid-state battery using a solid electrolyte. In an all-solid-state battery, the solid electrolyte also functions as a spacer. Generally, compared to lithium-ion batteries using liquid electrolytes, all-solid-state batteries have superior temperature resistance and longer lifespan.

[0044] In both single-cell batteries using liquid electrolytes and single-cell batteries using solid electrolytes, materials with excellent energy density but large expansion, such as metallic lithium or lithium-containing alloys, and silicon (Si), are sometimes used in the negative electrode. For example, lithium is deposited on the surface of a negative electrode made of metallic lithium due to repeated charging and discharging. When there is a deviation in the in-plane pressure distribution of the single cell 10, lithium deposition may be uneven. Uneven lithium deposition promotes the growth of deposited lithium in a protruding shape, raising concerns that it may reach the positive electrode and cause a short circuit. Therefore, it is required to apply pressure uniformly to all parts of the single cell 10 with an appropriate load.

[0045] Furthermore, in single cells using solid electrolytes, it is important to densify the solid electrolyte and improve the adhesion between the electrodes to ensure smooth ion movement between them. Therefore, it is required to apply pressure uniformly to all in-plane areas of the single cell 10 with an appropriate load.

[0046] The cushioning element 11 is a bag obtained by sealing a fluid such as gas or liquid inside an insulating bag-shaped packaging material. Based on the isotropic fluid pressure inside the cushioning element 11, the load acting on the single cell 10 sandwiched between two adjacent cushioning elements 11 is equalized at all points in the plane. The cushioning element 11 only needs to have cushioning and pressure equalization properties, and is not limited to the bag described above.

[0047] Reference Figures 2 to 7 An example of the manufacturing method of the storage battery 1 will be described below. For convenience, the stacking direction of the single battery 10 and the buffer member 11 will be described as the vertical direction.

[0048] like Figure 2 As shown, a single battery 10, a buffer member 11, a first surface pressure sensor 20, and a second surface pressure sensor 21 are stacked on the lower end plate 3a supported by the compression device. The first surface pressure sensor 20 is disposed at the center of the stacked body 12 in the stacking direction. The second surface pressure sensor 21 is disposed at the upper end of the stacked body 12 in the stacking direction, adjacent to the upper end plate 3b.

[0049] A vertical load is applied to the upper end plate 3b, compressing the laminate 12 in the lamination direction. During the compression process, the first surface pressure sensor 20 and the second surface pressure sensor 21 acquire the pressure distribution in the horizontal plane of the installation location.

[0050] After the laminate 12 is compressed, the frame 4 is assembled to the lower end plate 3a and the upper end plate 3b to form the battery 1. Then, the load applied to the upper end plate 3b is removed.

[0051] like Figure 4 As shown, in the compression process of the laminate 12, the laminate 12 is pressurized and compressed (step S1). The pressure distribution in the horizontal plane at the location of each sensor is obtained by the first surface pressure sensor 20 and the second surface pressure sensor 21, and the pressure distribution is monitored sequentially by the control unit of the compression device (step S2).

[0052] If the deviation of the surface pressure distribution at each sensor mounting location is less than a first predetermined value (step S3: No), compression of the laminate 12 continues. The deviation of the surface pressure distribution can be evaluated, for example, by the difference between the maximum and minimum pressure values ​​at various points within the surface, or by the standard deviation of the pressure. On the other hand, if the deviation of the surface pressure distribution at at least one sensor mounting location exceeds the first predetermined value (step S3: Yes), compression of the laminate 12 is interrupted, and decompression of the laminate 12 is performed (step S4).

[0053] Reference Figure 5Assuming that the single cell 10 and the buffer 11 at the center of the laminate 12 shift to the right in the figure, the posture of the laminate 12 relative to the lamination direction changes. In the surface pressure distribution at the center of the laminate 12 obtained by the first surface pressure sensor 20, the pressure on the left side is relatively higher, and the pressure on the right side is relatively lower. Furthermore, in the surface pressure distribution at the upper end of the laminate 12 obtained by the second surface pressure sensor 21, the pressure on the left side is relatively lower, and the pressure on the right side is relatively higher. Based on this trend in pressure distribution, it is possible to detect the precursors of the positional shift of the single cell 10 and the buffer 11.

[0054] Therefore, when the deviation of the surface pressure distribution at at least one sensor location (e.g., the difference between the maximum and minimum pressure values ​​ΔP) exceeds a first predetermined value TH1, the compression of the laminate 12 is interrupted. This prevents positional shifts between the single cell 10 and the buffer 11.

[0055] During the process of decompressing the laminate 12 by interrupting the compression, the pressure distribution in the horizontal plane at the location of each sensor is acquired by the first surface pressure sensor 20 and the second surface pressure sensor 21, and the pressure distribution is monitored sequentially by the control unit of the compression device (step S5). Then, if the deviation of the surface pressure distribution at the location of at least one sensor is greater than a second predetermined value (step S6: No), the decompression of the laminate 12 continues. The second predetermined value is set to a value smaller than the first predetermined value. On the other hand, if the deviation of the surface pressure distribution at the location of each sensor is less than the second predetermined value (step S6: Yes), the decompression of the laminate 12 is stopped (step S7).

[0056] Reference Figure 6 As the pressure on the laminate 12 is reduced, the compressed laminate 12 recovers according to the amount of pressure reduction. With the recovery of the laminate 12, the surface pressure distribution becomes more uniform. The pressure reduction of the laminate 12 is stopped when the deviation of the surface pressure distribution at each sensor location (e.g., the difference between the maximum and minimum pressure values ​​ΔP) falls below a second predetermined value TH2. Afterwards, as... Figure 7 As shown, the pressure on the laminate 12 is resumed, and the laminate 12 is compressed.

[0057] The compression of the laminate 12 is completed when the height of the laminate 12 reaches the specified height (step S8: yes).

[0058] According to the above-described manufacturing method of the storage battery 1, the precursors of positional displacement of the single cell 10 and the buffer member 11 are detected based on the surface pressure distribution. If a precursor of positional displacement is detected, the compression of the laminate 12 is interrupted, and the pressure on the laminate 12 is reduced, thereby equalizing the surface pressure distribution. Then, after the surface pressure distribution is equalized, the compression of the laminate 12 is resumed. Thus, the laminate 12 can be compressed while maintaining the single cell 10 and the buffer member 11 in a neatly aligned state in the stacking direction. By maintaining the neat alignment of the single cell 10 and the buffer member 11 in the stacking direction, the assembly of the frame 4 becomes easier. Furthermore, it is possible to uniformly press all points in the plane intersecting the thickness direction of the single cell 10. This is useful when the single cell 10 is a single cell using a solid electrolyte, and also useful when the single cell 10 includes a negative electrode formed of lithium metal or the like.

[0059] In the above-described method for manufacturing the battery 1, the pressurization and depressurization of the laminate 12 are switched based on the pressure distribution in the plane intersecting the lamination direction of the laminate 12. However, the pressurization and depressurization of the laminate 12 can also be switched based on the displacement of the movable plate of the compression device.

[0060] like Figure 8 As shown, the laminate 12 is pressurized and compressed (step S11). The control unit sequentially monitors the displacement of the movable plate of the compression device in the compression direction (step S12).

[0061] Before the displacement of the movable plate in the compression direction reaches the first predetermined value (step S13: No), the compression of the laminate 12 continues. When the displacement of the movable plate in the compression direction reaches the first predetermined value (step S13: Yes), the compression of the laminate 12 is interrupted, and the laminate 12 is decompressed (step S14).

[0062] During the decompression of the laminate 12, the control unit sequentially monitors the displacement of the movable plate in the anti-compression direction (step S15). Before the displacement of the movable plate in the anti-compression direction reaches a second predetermined value (step S16: No), the decompression of the laminate 12 continues. When the displacement of the movable plate in the anti-compression direction reaches the second predetermined value (step S16: Yes), the decompression of the laminate 12 stops (step S17).

[0063] Then, the pressurization of the laminate 12 is started again. The pressurization and decompression of the laminate 12 are repeated until the height of the laminate 12 reaches the specified height (step S18: Yes), and the compression of the laminate 12 is completed.

[0064] The displacement of the movable plate in the compression direction is a non-cumulative displacement based on the position of the movable plate when pressurization of the laminate 12 begins or resumes. Similarly, the displacement of the movable plate in the anti-compression direction is a non-cumulative displacement based on the position of the movable plate when depressurization of the laminate 12 begins. The first predetermined value for the displacement in the compression direction and the second predetermined value for the displacement in the anti-compression direction can be set statistically, for example, as follows.

[0065] Reference Figure 5 and Figure 6 When the deviation of the surface pressure distribution at at least one sensor location exceeds a first predetermined value TH1, the displacement d1 in the compression direction of the movable plate is acquired. Similarly, taking the position of the movable plate at the start of decompression of the laminate 12 as a reference point, when the deviation of the surface pressure distribution at each sensor location is lower than a second predetermined value TH2, the displacement d2 in the anti-compression direction of the movable plate is acquired.

[0066] Furthermore, through the manufacture of multiple batteries 1, the displacement amount d1 for each pressurization and the displacement amount d2 for each depressurization are accumulated. Based on the accumulated multiple displacement amounts d1, a first predetermined value for the displacement amount in the compression direction is set, and based on the accumulated multiple displacement amounts d2, a second predetermined value for the displacement amount in the anti-compression direction is set.

[0067] The first predetermined value for the amount of displacement in the compression direction, as set above, can be considered a statistical limit line for the increased risk of positional displacement of the single cell 10 and the buffer 11. Furthermore, the second predetermined value for the amount of displacement in the anti-compression direction can be considered a statistical safety line for the risk of positional displacement of the single cell 10 and the buffer 11 due to compression being reset.

[0068] By switching the pressure and depressurization of the laminate 12 based on the displacement of the movable plate of the compression device, the surface pressure sensor can be omitted, simplifying the manufacturing of the battery 1.

[0069] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments and can be appropriately modified and improved. For example, instead of a bag formed by sealing fluid in packaging material, it may also be, as... Figure 9As shown, the buffer 11 has a pair of foam bodies 30, which are arranged on both outer sides of the laminate 12 in the lamination direction, serving as first elastic members, and a wave-shaped leaf spring 31, which is arranged between the pair of foam bodies 30, serving as a second elastic member. The wave-shaped leaf spring 31 has alternating and continuous recesses and protrusions, forming a spring structure arranged in a horizontal plane perpendicular to the lamination direction. The foam bodies 30 reduce the pressure difference between the contact portions and non-contact portions of the leaf spring 31, improving the uniformity of surface pressure. Furthermore, multiple leaf springs 31 can be stacked in the lamination direction; alternatively, multiple arc-shaped leaf springs can be arranged in a horizontal plane instead of wave-shaped leaf springs 31.

[0070] At least the following items are described in this specification. Furthermore, although the corresponding components and the like are shown in parentheses in the above embodiments, the present invention is not limited thereto.

[0071] (1) A method for manufacturing a storage battery (storage battery 1), wherein the storage battery comprises a plurality of buffer components (buffer components 11) stacked together and a plurality of single cells (single cells 10) respectively disposed between two adjacent buffer components, wherein,

[0072] The battery manufacturing method involves repeatedly pressurizing and depressurizing the stacked body (stack 12) of the plurality of single cells and the plurality of buffer components in the stacking direction according to the posture change of the stacked body relative to the stacking direction, while simultaneously compressing the stacked body.

[0073] According to the battery manufacturing method described in (1) above, the stacked body can be compressed while maintaining the single cells and buffer components in a neatly arranged state in the stacking direction.

[0074] (2) The battery manufacturing method according to (1) above, wherein,

[0075] At one or more locations along the stacking direction of the laminated body, the in-plane pressure distribution in a direction intersecting the stacking direction is measured.

[0076] The pressurization and depressurization of the laminate are switched based on the pressure distribution.

[0077] According to the battery manufacturing method described in (2) above, it is possible to detect the precursors of positional displacement of individual cells and buffer components based on surface pressure distribution.

[0078] (3) The battery manufacturing method according to (2) above, wherein,

[0079] Pressure reduction is performed when the deviation of the pressure distribution exceeds a first predetermined value.

[0080] Pressurization is performed when the deviation of the pressure distribution is lower than a second specified value that is smaller than the first specified value.

[0081] According to the battery manufacturing method described in (3) above, it is possible to accurately switch between pressurization and depressurization of the laminate based on the surface pressure distribution.

[0082] (4) The battery manufacturing method according to (2) above, wherein,

[0083] The pressure distribution measurement site includes the central portion of the laminate in the lamination direction.

[0084] According to the battery manufacturing method described in (4) above, it is possible to accurately detect the precursors of positional displacement of individual cells and buffer components based on surface pressure distribution.

[0085] (5) The battery manufacturing method according to (1) above, wherein,

[0086] The pressurization and depressurization of the laminate are switched based on the displacement of the movable plate of the compression device.

[0087] The battery manufacturing method described in (5) above simplifies the manufacturing process of batteries.

[0088] (6) The method for manufacturing a storage battery according to (5) above, wherein,

[0089] Decompression is performed when the non-cumulative displacement of the movable plate in the compression direction, which accompanies the pressurization, reaches a first predetermined value.

[0090] Pressurization is applied when the non-cumulative displacement of the movable plate in the reverse compression direction, which accompanies decompression, reaches a second predetermined value that is smaller than the first predetermined value.

[0091] According to the battery manufacturing method described in (6) above, it is possible to accurately switch between pressurization and depressurization of the laminate based on the displacement of the movable plate.

[0092] (7) The method for manufacturing a storage battery according to any one of (1) to (6) above, wherein,

[0093] The single cell contains a solid electrolyte.

[0094] (8) The method for manufacturing a storage battery according to any one of (1) to (6) above, wherein,

[0095] The negative electrode of the single cell contains lithium metal or an alloy containing lithium metal.

[0096] (9) The method for manufacturing a storage battery according to any one of (1) to (6) above, wherein,

[0097] The negative electrode of the single cell contains silicon.

[0098] (10) The method for manufacturing a storage battery according to any one of (1) to (6) above, wherein,

[0099] The cushioning element contains fluid sealed within packaging material.

[0100] (11) The method for manufacturing a storage battery according to any one of (1) to (6) above, wherein,

[0101] The buffer has:

[0102] A pair of first elastic members (foam bodies 30) disposed on both sides of the lamination direction; and

[0103] A second elastic member (leaf spring 31) is disposed between the pair of first elastic members.

[0104] The second elastic component includes a spring structure arranged in a plane intersecting the stacking direction.

Claims

1. A method for manufacturing a storage battery, wherein the storage battery comprises a plurality of buffer elements stacked together and a plurality of individual cells respectively disposed between two adjacent buffer elements, wherein, The battery manufacturing method involves repeatedly pressurizing and depressurizing the stacked body of the plurality of individual cells and the plurality of buffer components in the stacking direction according to the posture changes of the stacked body relative to the stacking direction, while simultaneously compressing the stacked body.

2. The method for manufacturing a storage battery according to claim 1, wherein, At one or more locations along the stacking direction of the laminated body, the in-plane pressure distribution in a direction intersecting the stacking direction is measured. The pressurization and depressurization of the laminate are switched based on the pressure distribution.

3. The method for manufacturing a storage battery according to claim 2, wherein, Pressure reduction is performed when the deviation of the pressure distribution exceeds a first predetermined value. Pressurization is performed when the deviation of the pressure distribution is lower than a second specified value that is smaller than the first specified value.

4. The method for manufacturing a storage battery according to claim 2, wherein, The pressure distribution measurement site includes the central portion of the laminate in the lamination direction.

5. The method for manufacturing a storage battery according to claim 1, wherein, The pressurization and depressurization of the laminate are switched based on the displacement of the movable plate of the compression device.

6. The method for manufacturing a storage battery according to claim 5, wherein, Decompression is performed when the non-cumulative displacement of the movable plate in the compression direction, which accompanies the pressurization, reaches a first predetermined value. Pressurization is applied when the non-cumulative displacement of the movable plate in the reverse compression direction, which accompanies decompression, reaches a second predetermined value that is smaller than the first predetermined value.

7. The method for manufacturing a storage battery according to any one of claims 1 to 6, wherein, The single cell contains a solid electrolyte.

8. The method for manufacturing a storage battery according to any one of claims 1 to 6, wherein, The negative electrode of the single cell contains lithium metal or an alloy containing lithium metal.

9. The method for manufacturing a storage battery according to any one of claims 1 to 6, wherein, The negative electrode of the single cell contains silicon.

10. A method for manufacturing a storage battery according to any one of claims 1 to 6, wherein, The cushioning element contains fluid sealed within packaging material.

11. The method for manufacturing a storage battery according to any one of claims 1 to 6, wherein, The buffer has: A pair of first elastic members disposed on both sides of the stacking direction; and The second elastic member is disposed between the pair of first elastic members. The second elastic component includes a spring structure arranged in a plane intersecting the stacking direction.

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