Square battery and method of manufacturing square battery

Abstract

The present invention relates to a square battery and a manufacturing method of a square battery. The square battery (10) of the present invention includes a substantially rectangular lid (30) provided with a terminal (50), a substantially cuboid housing main body (20) provided with two pairs of opposing side surfaces (21, 22) connected to a peripheral edge portion of the lid (30), and an electrode body (40) housed inside the housing main body (20) and connected to the terminal (50). At least one side surface (22) of the two pairs of opposing side surfaces (21, 22) is contracted toward an inner side of the housing main body (20) so as to abut against the electrode body (40) together with the side surface (22) opposing the side surface (22).

Description

Technical Field

[0001] This invention relates to square batteries and methods for manufacturing square batteries. Background Technology

[0002] For example, Japanese Patent Application Publication No. 2004-228035 discloses a method for manufacturing a cylindrical battery that includes a diameter-reduction step in which the sidewall of an outer can housing a spiral electrode body is reduced radially inward. In the diameter-reduction step disclosed in Japanese Patent Application Publication No. 2004-228035, the outer can is passed through a conical through-hole, thereby performing a stretching process over the entire area from the bottom portion of the sidewall of the outer can to the opening edge. According to Japanese Patent Application Publication No. 2004-228035, this method enables the manufacture of batteries with a higher capacity relative to their volume. Japanese Patent Application Publication No. 2004-228035 also describes prismatic lithium-ion batteries as a possible candidate.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2004-228035

[0004] In a square battery where the electrodes are housed within a roughly rectangular casing, it is also necessary to suppress the movement of the electrodes within the casing. Summary of the Invention

[0005] The square battery disclosed herein comprises: a generally rectangular cover with terminals; a generally rectangular housing body having two pairs of opposing sides connected to the periphery of the cover; and electrode bodies housed inside the housing body and connected to the terminals. At least one of the two pairs of opposing sides tapers toward the inside of the housing body so as to abut against the electrode body together with the side opposite to that side.

[0006] According to the aforementioned square battery, at least one pair of sides of the outer casing abut against the electrode body to press the electrode body. Therefore, movement of the electrode body within the outer casing is suppressed.

[0007] The method for manufacturing a square battery disclosed herein includes: a step of housing an electrode body inside a generally rectangular cuboid casing body; and a step of pressing at least one side of the casing body to deform the pressed side in such a way that the pressed side and the side opposite to the pressed side abut against the electrode body. According to the above method for manufacturing a square battery, it is possible to manufacture a square battery that suppresses movement of the electrode body within the casing body.

[0008] Alternatively, based on the aforementioned square battery, the two pairs of opposing sides include a pair of wide sides and a pair of narrow sides. At least one of the pair of narrow sides tapers inward toward the inner side of the casing body so that it, together with the narrow side opposite to it, abuts against the electrode body, while at least one of the pair of wide sides separates from the electrode body. Alternatively, based on the aforementioned square battery manufacturing method, the sides of the casing body include a side for mounting a cover with terminals, and a pair of wide sides and a pair of narrow sides respectively connected to the side for mounting the cover. In the step of deforming the sides, at least one of the pair of narrow sides is deformed.

[0009] Alternatively, based on the aforementioned square battery, the constricted side of the outer casing body has an abutment portion that abuts against the electrode body, and separation portions located on both sides of the abutment portion and separated from the electrode body. Alternatively, based on the aforementioned square battery manufacturing method, in the step of deforming the side surface, a portion of the pressed side surface is pressed. Attached Figure Description

[0010] Figure 1 This is a partial cross-sectional view of a square battery.

[0011] Figure 2 This is a schematic diagram illustrating a part of the manufacturing process of a square battery.

[0012] Figure 3 This is a partial cross-sectional view of the square battery involved in the first variation.

[0013] Figure 4 This is a partial cross-sectional view of the square battery involved in the second variation. Detailed Implementation

[0014] The following describes one embodiment of a square battery. However, the embodiment described herein is not intended to specifically limit the invention. Furthermore, the accompanying drawings are schematic diagrams and do not necessarily faithfully reflect the actual components. Hereinafter, components and parts that perform the same function will be labeled with the same reference numerals, and repeated descriptions will be omitted or simplified as appropriate.

[0015] [Structure of a square battery]

[0016] Figure 1 This is a partial cross-sectional view of the square battery 10. Figure 1 This is a view taken from one side (one of the pair of wide surfaces 21 described later) of the generally rectangular outer casing 20, depicted with a portion of the interior of the outer casing 20 exposed. Figure 1 As shown, the square battery 10 includes a housing body 20, a cover 30, an electrode body 40, electrode terminals 50, a gasket 61, and an insulating component 62.

[0017] The outer casing 20 houses the electrode body 40 and the electrolyte. The outer casing 20 is a flat, rectangular container that is approximately cuboid in shape. Here, "approximately cuboid" means that, in addition to a cube, it also includes shapes that can almost be considered cubic, such as those with chamfered or rounded corners. The outer casing 20 has a pair of opposing side surfaces 21, another pair of opposing side surfaces 22, a bottom surface 23, and an opening 24 opposite the bottom surface 23. The opening 24 is a side surface of the outer casing 20 for mounting the cover 30. Hereinafter, one pair of the wider side surfaces of the two pairs of side surfaces 21, 22 will be referred to as a pair of wide surfaces 21. Additionally, one pair of the narrower side surfaces of the two pairs of side surfaces 21, 22 will be referred to as a pair of narrow surfaces 22. For example, as... Figure 2 As shown, the width of the narrow surface 22 ( Figure 1 The length of the paper in the depth direction is greater than the width of the width format 21. Figure 1 The length in the left-right direction is short. A pair of wide surfaces 21 and a pair of narrow surfaces 22 are connected to the opening 24 on the side for mounting the cover 30. The outer casing body 20 is formed, for example, of aluminum or aluminum alloy.

[0018] A cover 30 is installed on the opening 24 of the housing body 20, blocking the opening 24. The cover 30 is a plate-shaped component. The cover 30 is generally rectangular and has electrode terminals 50. Here, "generally rectangular" means that, in addition to being rectangular, it also includes shapes that can be considered almost rectangular, such as shapes with holes, recesses, protrusions, etc. A pair of wide surfaces 21 and a pair of narrow surfaces 22 of the housing body 20 are connected to the periphery of the cover 30. The cover 30 is, for example, made of aluminum or an aluminum alloy. A through hole 31 is provided near each of the two ends along the long side of the cover 30. Electrode terminals 50 are inserted into each of the two through holes 31. One of the two electrode terminals 50 is a positive terminal 50P, and the other is a negative terminal 50N.

[0019] The electrode body 40 is housed inside the outer casing 20. The electrode body 40 includes a positive electrode 41, a negative electrode 42, a first insulating sheet 43, and a second insulating sheet 44. The first insulating sheet 43, the positive electrode 41, the second insulating sheet 44, and the negative electrode 42 are stacked multiple times to form a laminated electrode body. However, the first insulating sheet 43, the positive electrode 41, the second insulating sheet 44, and the negative electrode 42 can also be wound after overlapping to form a wound electrode body. Here, the electrode body 40 is housed inside the outer casing 20 with an electrode body support 45 fitted with an insulator. The electrode body support 45 is, for example, made of an insulating film, and covers the first insulating sheet 43, the positive electrode 41, the second insulating sheet 44, and the negative electrode 42 in a manner that prevents the positive electrode 41 or the negative electrode 42 from contacting the outer casing 20. However, the electrode body support 45 is not limited to an insulating film; for example, it can be a box-shaped component capable of elastic deformation.

[0020] The first insulating plate 43 and the second insulating plate 44 are larger than the positive electrode plate 41 and the negative electrode plate 42, and extend outward from them. This prevents the positive electrode plate 41 from contacting the negative electrode plate 42. The positive electrode plate 41 and the negative electrode plate 42 each have tabs 41a and 42a that are connected to the positive terminal 50P and the negative terminal 50N, respectively.

[0021] In this embodiment, the square battery 10 is a secondary battery in which a positive active material layer is formed on the positive electrode 41 and a negative active material layer is formed on the negative electrode 42. The type of square battery 10 is not particularly limited, but it can be, for example, a lithium-ion secondary battery. The first separator 43, the positive electrode 41, the second separator 44, and the negative electrode 42 are arranged in the direction of a pair of wide surfaces 21 of the outer casing 20. Figure 1 (The paper is stacked in the depth direction) on top.

[0022] Electrode terminal 50 is connected to electrode body 40. Specifically, positive terminal 50P is connected to tab 41a of positive electrode plate 41. Negative terminal 50N is connected to tab 42a of negative electrode plate 42. Electrode terminal 50 includes current collector terminal 51, external terminal 52, and bolt terminal 53. Current collector terminal 51 is inserted into the interior of housing body 20 through through hole 31 of cover 30 and connected to tab 41a or tab 42a. External terminal 52 is arranged along the upper surface of cover 30 and connected to current collector terminal 51. Bolt terminal 53 is connected to external terminal 52. A gasket 61 formed of insulator is sandwiched between cover 30 and current collector terminal 51. Gasket 61 electrically insulates between cover 30 and current collector terminal 51 and seals through hole 31. An insulating member 62 formed of insulator is sandwiched between cover 30 and external terminal 52. Insulating member 62 electrically insulates between cover 30 and external terminal 52.

[0023] At least one of the two pairs of side surfaces 21 and 22 of the outer casing 20 tapers inward toward the inner side of the outer casing 20 so as to abut against the electrode body 40 together with the side surface opposite to that surface. Viewed from side surface 21 or 22 of the outer casing 20, the inner side of the outer casing 20 faces the electrode body 40, for example, in... Figure 1 In the case of the narrow right-side section 22, it is on the left. In this embodiment, as... Figure 1 As shown, a contraction is formed on a pair of narrow surfaces 22 that abuts against the electrode body 40. In this embodiment, no contraction is formed on a pair of wide surfaces 21.

[0024] However, the contraction may not be formed on the pair of narrow surfaces 22 but on the pair of wide surfaces 21. Alternatively, the contraction may be formed on both the pair of narrow surfaces 22 and the pair of wide surfaces 21. Furthermore, the contraction may not be formed on both of the pair of narrow surfaces 22 but only on one side. When the contraction is formed only on one side of the pair of narrow surfaces 22, both the contracted narrow surface 22 and its opposite narrow surface 22 abut against the electrode body 40. Similarly, the contraction may be formed only on one side of the pair of wide surfaces 21. In addition, "abutting" the side surface 21 or 22 of the outer casing 20 against the electrode body 40 means that the electrode body 40 is pressed by the outer casing 20 in a manner that makes it difficult for the electrode body 40 to move. The abutting of the side surface 21 or 22 of the outer casing 20 against the electrode body 40 includes not only the side surface 21 or 22 directly contacting the electrode body 40, but also the side surface 21 or 22 pressing the electrode body 40 via a component capable of transmitting the pressing force, such as the electrode body support 45.

[0025] In this embodiment, each narrow surface 22 has an abutting portion 22a that abuts against the electrode body 40 and a separating portion 22b that separates from the electrode body 40. The separating portions 22b are located on both sides of the abutting portion 22a. Here, the separating portion 22b is located on the side closer to the bottom surface 23 of the outer casing body 20 than the abutting portion 22a. Figure 1 Below), and the side of the contact portion 22a near the cover 30 ( Figure 1 Above). The contact portion 22a is formed along the long side of the narrow surface 22 ( Figure 1 The central part (vertical direction). If viewed towards the wide surface 21, the abutment portion 22a is recessed into an isosceles triangular shape towards the inner side of the outer shell body 20. Although the figure is omitted, the abutment portion 22a extends throughout the width direction of the narrow surface 22 (vertical direction). Figure 1 The abutment portion 22a is formed across the entire width (in the depth direction). The abutment portion 22a presses against the electrode body 40 in a manner that prevents the electrode body 40 from easily moving within the outer casing 20. However, the abutment portion 22a may also be formed only in the width direction (in the depth direction) of the narrow surface 22. Figure 1 (part of the depth direction).

[0026] At least one of the wide surfaces 21 is separated from the electrode body 40. In other words, the width of the narrow surface 22 (the distance between the pair of wide surfaces 21) is greater than the thickness of the electrode body 40. For manufacturing reasons, there is a possibility that the electrode body 40 may come into contact with either of the wide surfaces 21, but not with both of them. Thus, in the arrangement direction of the wide surfaces 21, a dimensional margin is created for the electrode body 40 to expand and contract during charging and discharging.

[0027] [Manufacturing method of square batteries]

[0028] Figure 2 This is a schematic diagram illustrating a part of the manufacturing process of the square battery 10. (As shown...) Figure 2 As shown, the manufacturing process of the square battery 10 includes step S10 of housing the electrode body 40 inside the generally rectangular shell body 20, step S20 of welding the cover 30 to the shell body 20, and step S30 of deforming a pair of narrow surfaces 22 to form the abutment portion 22a. However, Figure 2 The process shown is merely a preferred example. For instance, as described above, the side of the outer casing body 20 forming the abutment portion is not limited. Therefore, in the step of forming the abutment portion, at least one side of the outer casing body 20 is pressed, and the pressed side is deformed such that the pressed side and the opposite side abut against the electrode body 40. Furthermore, the method disclosed in the embodiment does not limit the manufacturing method of the square battery 10.

[0029] like Figure 2 As shown, step S10, which houses the electrode body 40 inside the generally rectangular outer shell 20, includes step S11, which involves fabricating the electrode body 40; step S12, which involves joining two electrode bodies 40 to the assembly of the cover 30 and the electrode terminal 50; step S13, which involves folding the two electrode bodies 40; step S14, which involves covering the assembly of the cover 30, the electrode body 40, and the electrode terminal 50 with the electrode body support 45; and step S15, which involves installing the assembly of the cover 30, the electrode body 40, the electrode terminal 50, and the electrode body support 45 onto the outer shell 20.

[0030] The details of step S11 are omitted. In step S12, as... Figure 2 As shown, two electrode bodies 40 are positioned on both sides of the cover 30, and in this state, the collector terminal 51 of the positive terminal 50P (refer to...) Figure 1In step S13, the tabs 41a of the positive electrode 41 are welded, and the tabs 42a of the negative electrode 42 are welded to the current collector terminal 51 of the negative terminal 50N. In step S14, the tabs 41a and 42a are bent to fold the two electrode bodies 40 so that their wide surfaces are tightly pressed together. In step S15, the electrode body bracket 45 is placed over the assembly of the folded electrode body 40, the electrode body 40, and the electrode terminal 50. As a result, the portion of the assembly housed within the outer casing 20 (including the positive electrode 41, the negative electrode 42, the first insulating sheet 43, and the second insulating sheet 44) is covered by the electrode body bracket 45. In step S16, the assembly with the electrode body bracket 45 covered is installed on the outer casing 20. As a result, the cover 30 is installed at the opening 24 of the outer casing 20. In addition, the electrode body 40 is housed inside the outer casing 20.

[0031] In step S20, the cover 30 is welded to the outer casing body 20. Alternatively, step S20 can be performed after step S30, where the abutment portion 22a is formed on the outer casing body 20.

[0032] In step S30, a pair of narrow surfaces 22 are deformed to form abutment portions 22a on each of the pair of narrow surfaces 22. Step S30 includes: step S31, mounting the square battery 10 (although not yet a finished product, it will be referred to as square battery 10 for convenience) after step S20 onto the pressing clamp 100 where the abutment portions 22a are formed; step S32, pressing the pressing clamp 100 by stamping (not shown) to form the abutment portions 22a; and step S33, removing the square battery 10 from the pressing clamp 100.

[0033] Although detailed illustrations of step S31 are omitted, the pressing clamp 100 with the square battery 10 mounted becomes... Figure 2 The state shown. As indicated. Figure 2 As shown, the pressing clamp 100 includes a bottom-side fixing mold 101, a cover-side fixing mold 102, a first pressing mold 103, and a second pressing mold 104. The bottom-side fixing mold 101 abuts against the bottom surface 23 of the outer casing body 20. The cover-side fixing mold 102 abuts against the cover 30. The bottom-side fixing mold 101 and the cover-side fixing mold 102 hold the square battery 10. The first pressing mold 103 abuts against a narrow surface 22. The first pressing mold 103 has a protrusion with a shape corresponding to the shape of the abutment portion 22a. The second pressing mold 104 abuts against another narrow surface 22. The second pressing mold 104 also has a protrusion with a shape corresponding to the shape of the abutment portion 22a.

[0034] As in Figure 2As indicated by the arrows, the stamping (not shown) is performed to bring the first pressing die 103 and the second pressing die 104 close together. The stamping, for example, presses the first pressing die 103 and the second pressing die 104 in such a way that the edges of the first partition plate 43 and the second partition plate 44 are crushed by a predetermined amount according to the dimensions in the accompanying drawings. The predetermined amount is preferably, for example, about 0.5 mm on one side in the stamping direction. However, the amount by which the pressing clamp 100 deforms the outer casing body 20 is not limited to the above.

[0035] Furthermore, when the abutment portion 22a is formed only on one side of the narrow surface 22, the pressing mold 103 or 104 on the side where the abutment portion 22a is not formed may also have a flat shape. Alternatively, the abutment portion 22a may be formed over all or almost all of the narrow surface 22, in which case the abutment portion 22a may be formed, for example, by stretching.

[0036] [Effects of the Implementation Method]

[0037] As described above, the square battery 10 according to this embodiment includes: a generally rectangular cover 30 with electrode terminals 50; a generally rectangular outer casing 20 with two pairs of opposing side surfaces 21, 22 connected to the periphery of the cover 30; and an electrode body 40 housed inside the outer casing 20 and connected to the electrode terminals 50. At least one of the two pairs of opposing side surfaces 21, 22 tapers toward the inside of the outer casing 20 so as to abut against the electrode body 40 together with the side surface opposite to that side surface. According to this square battery 10, at least one pair of side surfaces of the outer casing 20 abut against the electrode body 40 to press the electrode body 40. Therefore, movement of the electrode body 40 within the outer casing 20 is suppressed. In addition, in this embodiment, the inner dimensions of the outer casing 20 are reliably made larger than the electrode body 40, and a tapering occurs after the electrode body 40 is housed in the outer casing 20, thereby making it easy to house the electrode body 40 within the outer casing 20.

[0038] In this embodiment, the two pairs of side surfaces 21, 22 of the outer casing 20 include a pair of wide surfaces 21 and a pair of narrow surfaces 22. At least one of the pair of narrow surfaces 22 tapers inward toward the inner side of the outer casing 20 so as to abut against the electrode body 40 together with the narrow surface 22 opposite to it. On the other hand, at least one of the pair of wide surfaces 21 is separated from the electrode body 40. According to this square battery 10, the movement of the electrode body 40 can be suppressed by the pair of narrow surfaces 22, and a margin for expansion of the electrode body 40 can be generated in the arrangement direction of the pair of wide surfaces 21. The electrode body 40 expands mainly in the arrangement direction of the wide surfaces 21, which is the stacking direction of the first separator 43, the positive electrode 41, the second separator 44, and the negative electrode 42. Therefore, it is preferable that the square battery 10 has a gap in the arrangement direction of the pair of wide surfaces 21 in which the electrode body 40 can expand. Without such a gap, the first separator 43 and the second separator 44 would gradually collapse, potentially deteriorating the battery's characteristics.

[0039] In this embodiment, the constricted sides (here, a pair of narrow surfaces 22) of the outer casing 20 have abutting portions 22a that abut against the electrode body 40, and separating portions 22b located on both sides of the abutting portions 22a and separated from the electrode body 40. When deforming the sides of the outer casing 20 to form the abutting portions 22a, it is easier to deform the sides so that only a portion of the sides abut against the electrode body 40 than to deform the sides so that the entire sides abut against the electrode body 40. Therefore, this square battery 10 can be manufactured more easily. In addition, since the electrolyte enters the gap between the separating portions 22b and the electrode body 40, the performance as a battery can be improved. In the event that gas is generated by the reaction between the electrode body 40 and the electrolyte, the gap between the separating portions 22b and the electrode body 40 can also function as a gas release space.

[0040] The manufacturing method of the square battery 10 according to this embodiment includes a step S10 of housing an electrode body 40 inside a generally rectangular box body 20, and a step S30 of pressing at least one side of the box body 20 to deform the pressed side in such a way that the pressed side and the side opposite to the pressed side abut against the electrode body 40. According to this manufacturing method of the square battery 10, it is possible to manufacture a square battery 10 in which the electrode body 40 is not easily moved within the box body 20.

[0041] In this embodiment, the side surface of the outer casing 20 includes a side surface (opening 24) for mounting a cover 30 on which electrode terminals 50 are provided, and a pair of wide surfaces 21 and a pair of narrow surfaces 22 respectively connected to the side surface (opening 24) on which the cover 30 is mounted. In step S30 of deforming the side surface of the outer casing 20, at least one of the pair of narrow surfaces 22 is deformed. According to this method of manufacturing the square battery 10, it is possible to manufacture a square battery 10 that suppresses the movement of the electrode body 40 through the pair of narrow surfaces 22 and has a slit for the expansion of the electrode body 40 in the arrangement direction of the pair of wide surfaces 21.

[0042] [Variations on the implementation method]

[0043] The aforementioned square battery 10 can also be implemented in other forms. Figure 3 This is a partial cross-sectional view of the square battery 10 involved in the first modified example. (See attached image.) Figure 3 As shown, in this modified example, only a portion of the narrow surface 22 is deformed (in... Figure 1 In the square battery 10, the abutment portion 22a abuts against the electrode body 40, but it is deformed in such a way that the narrow surface 22 is completely or almost completely recessed. Thus, during the step of deforming the side of the casing body 20, a portion of the pressed side can also be pressed. According to this manufacturing method, when forming the abutment portion 22a, the side of the casing body 20 is not deformed except for the abutment portion 22a and its supporting portion 22c. Therefore, it is easier (e.g., using a stamping process with lower stamping pressure) to deform the side of the casing body 20. Furthermore, the shape of the abutment portion 22a is not limited to... Figure 3 It has a trapezoidal shape as shown.

[0044] Figure 4 This is a partial cross-sectional view of the square battery 10 involved in the second variation. (See attached image.) Figure 4 As shown, in this modified example, multiple abutment portions 22a and multiple separation portions 22b are formed on the side of the outer casing 20. The multiple abutment portions 22a and multiple separation portions 22b are alternately connected in such a way that the side of the outer casing 20 is undulating. According to this square battery 10, the electrode body 40 is pressed on one side by the multiple abutment portions 22a. Therefore, the pressing of the electrode body 40 is more stable. Furthermore, the number and position of the abutment portions 22a are not particularly limited.

[0045] Furthermore, the initial embodiments and variations can be appropriately combined. For example, different shapes or different numbers of contractions can be formed on one or the other of a pair of narrow surfaces 22 (or wide surfaces 21).

[0046] The foregoing has provided various descriptions of the square battery and its manufacturing method. Unless otherwise specified, the embodiments of the square battery described herein are not intended to limit the present invention.

Claims

1. A square battery, wherein, The square battery has the following features: The cover is roughly rectangular and has terminals. The main body of the shell is generally rectangular, having two pairs of opposing sides connected to the periphery of the cover; and The electrode body is housed inside the main housing and connected to the terminal. At least one of the two pairs of opposing sides tapers inward toward the inner side of the housing body so that it, together with the side opposite to that side, abuts against the electrode body. The two pairs of opposing sides include a pair of wide sides and a pair of narrow sides. At least one of the pair of narrow sides tapers inward toward the inner side of the housing body so that it, together with the narrow side opposite to it, abuts against the electrode body. At least one of the pair of wide sides is separated from the electrode body. The wide sidewalls are arranged in the stacking direction of the first insulating sheet, the positive electrode sheet, the second insulating sheet, and the negative electrode sheet in the electrode body.

2. The square battery according to claim 1, wherein, The constricted side of the outer shell body has an abutting portion that abuts against the electrode body, and a separating portion located on both sides of the abutting portion and separated from the electrode body.

3. A method for manufacturing a square battery, wherein, The method for manufacturing the square battery includes: The steps of housing the electrode body inside the roughly rectangular outer shell; and The step of pressing at least one side of the outer casing body to deform the pressed side in such a way that the pressed side and the side opposite to the pressed side abut against the electrode body. The outer casing body includes a side for mounting a cover with terminals, a pair of wide side panels and a pair of narrow side panels respectively connected to the side for mounting the cover. The wide sidewalls are arranged in the stacking direction of the first insulating sheet, the positive electrode sheet, the second insulating sheet, and the negative electrode sheet in the electrode body. In the step of deforming the side surface, at least one of the pair of narrow side surfaces is deformed, while at least one of the pair of wide side surfaces is separated from the electrode body.

4. The method for manufacturing a square battery according to claim 3, wherein, In the step of deforming the side, a portion of the pressed side is pressed.

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