Secondary battery

Abstract

The utility model provides a secondary battery which can well apply load to a winding body when the secondary battery is activated. A secondary battery (1) is provided with: a wound body (2) formed by winding a laminate of a positive electrode, a separator, and a negative electrode; a case (5) that accommodates the wound body (2); and a foam body (6) which is disposed between the wound body (2) and the case (5) and has insulating properties, and in which a convex part (5b) for pressing the wound body (2) by the foam body (6) is formed on a side part of the case (5).

Description

Technical Field

[0001] The present disclosure relates to a secondary battery. Background Art

[0002] For example, a general secondary battery such as a lithium ion battery disclosed in Patent Document 1 comprises a wound body formed by winding a stack of a positive electrode, a separator, and a negative electrode, and an insulator such as a porous elastic body disposed between a case accommodating the wound body.

[0003] Patent Document 1: Japanese Patent No. 6656624

[0004] The applicant has discovered the following problem. In typical secondary batteries, a load must be applied to the wound body during activation. However, since the wound body is surrounded by an insulator such as a porous elastomer, it is difficult to effectively apply the load to the wound body during activation. Utility Model Content

[0005] The present disclosure has been made in view of the above-mentioned problems, and realizes a secondary battery capable of satisfactorily applying a load to a wound body when activating the secondary battery.

[0006] According to one embodiment of the present disclosure, a secondary battery comprises: a wound body formed by winding a stack of a positive electrode, a separator, and a negative electrode; a shell that houses the wound body; and a foam that is arranged between the wound body and the shell and has insulating properties, and a convex portion is formed on the side of the shell to press the wound body through the foam.

[0007] In the above-mentioned secondary battery, it is preferable that a holding portion for holding the foam body is formed on the bottom of the case.

[0008] In the secondary battery described above, the protrusion is preferably a rib extending in an insertion direction of the wound body into the case.

[0009] In the secondary battery, the foam is preferably a closed-cell foam.

[0010] In the above-mentioned secondary battery, it is preferable that the convex portion presses the wound body through the foam when activating the secondary battery.

[0011] According to the present disclosure, it is possible to realize a secondary battery capable of satisfactorily applying a load to a wound body when activating the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 4 is a cross-sectional view of the secondary battery according to the embodiment as viewed from the Y-axis side.

[0013] Figure 2This is a cross-sectional view of the secondary battery according to the embodiment as viewed from the Z-axis + side.

[0014] Figure 3 It is a figure which shows the foam body in the secondary battery of embodiment.

[0015] Figure 4 This is a diagram showing the relationship between the restraining force when restraining a battery module and the load applied to the wound body of the secondary battery.

[0016] Figure 5 This is a cross-sectional view of a secondary battery according to another embodiment as viewed from the Z-axis + side. DETAILED DESCRIPTION

[0017] Specific embodiments to which the present disclosure is applied are described in detail below with reference to the accompanying drawings. However, the present disclosure is not limited to the following embodiments. Furthermore, the following description and drawings have been appropriately simplified for clarity. In the following description, a three-dimensional (XYZ) coordinate system is used for clarity.

[0018] Figure 1 4 is a cross-sectional view of the secondary battery of this embodiment as viewed from the Y-axis side. Figure 2 This is a cross-sectional view of the secondary battery of this embodiment as viewed from the Z-axis + side. Figure 3 : is a diagram showing a foamed body in a secondary battery of this embodiment. Figure 1 and Figure 2 The simplified design omits the terminals and covers of the secondary battery.

[0019] The secondary battery 1 of this embodiment is, for example, a lithium-ion battery cell, and a plurality of secondary batteries constitute a battery module. Figure 1 and Figure 2 As shown, the secondary battery 1 includes a wound body 2 , a positive electrode current collector 3 , a negative electrode current collector 4 , a case 5 , and a foam 6 .

[0020] The wound body 2 is formed by winding a laminated body in which a positive electrode, a separator, and a negative electrode are stacked. Figure 2 As shown, the wound body 2 is a generally rectangular shape that is long in the Y-axis direction when viewed from the Z-axis direction. The positive electrode current collector 3 is electrically connected to the positive electrode of the wound body 2 and is disposed, for example, on the Y-axis positive side of the wound body 2 .

[0021] The negative electrode current collector 4 is electrically connected to the negative electrode of the wound body 2 and is, for example, disposed on the Y-axis side of the wound body 2. Figure 1 and Figure 2 As shown, the wound body 2 , the positive electrode current collector 3 , and the negative electrode current collector 4 constitute an electrode assembly 7 .

[0022] like Figure 1 and Figure 2As shown, the case 5 accommodates the electrode assembly 7 and the foam body 6 covering the electrode assembly 7. The case 5 includes a case body 5a, a protrusion 5b, and a holding portion 5c, and can be made of, for example, aluminum.

[0023] like Figure 1 and Figure 2 As shown, the housing body 5a has a bottomed cylindrical shape with the Z-axis side closed, for example, a generally rectangular shape that is elongated in the Y-axis direction when viewed from the Z-axis direction. The protrusions 5b are formed, for example, on the X-axis positive side and the X-axis negative side of the housing body 5a, and protrude toward the inside of the housing body 5a.

[0024] like Figure 1 As shown, the convex portion 5b extends in the Z-axis direction and is arranged in a height region in the Z-axis direction where the wound body 2 is arranged. Figure 2 As shown, the convex portions 5b are arranged at substantially equal intervals in the Y-axis direction so as to face each other in the X-axis direction.

[0025] For example Figure 2 As shown, the protrusions 5b are generally rectangular columnar when viewed from the Z-axis direction. The thickness of the protrusions 5b in the X-axis direction may be sufficient to press the wound body 2 against the foam 6, and is preferably approximately 0.1 mm to 1 mm, for example. However, the arrangement, number, and shape of the protrusions 5b may be modified as appropriate.

[0026] like Figure 1 and Figure 2 As shown, the holding portion 5c holds the electrode assembly 7 via the foam 6. The holding portion 5c is arranged at the four corners on the Z-axis side of the housing body 5a, and recesses 5d are formed on the foam 6 side of the holding portion 5c to fit into the corners of the foam 6.

[0027] When the electrode assembly 7 held in the foam body 6 is inserted into the interior of the shell 5 and the electrolyte is injected, the open opening on the Z-axis + side of the shell 5 is covered by a cover (not shown), the positive electrode collector 3 is electrically connected to the positive terminal provided on the cover, and the negative electrode collector 4 is electrically connected to the negative terminal provided on the cover.

[0028] like Figure 1 and Figure 2 As shown in FIG. 1 , in order to electrically insulate the housing 5 from the electrode assembly 7, the foam 6 is disposed between the housing 5 and the electrode assembly 7. Figure 3 As shown, the foam body 6 is an independent foam type foam body, for example, made of polypropylene (PP), polyethylene (PE) or reactive polyurethane (PUR).

[0029] For example Figure 1 and Figure 2As shown, the foam body 6 has a generally rectangular shape that is elongated in the Y-axis direction when viewed from the Z-axis direction, and extends in the Z-axis direction. Furthermore, the foam body 6 has an insertion portion 6a for inserting the electrode assembly 7. When the electrode assembly 7 is inserted into the insertion portion 6a, the foam body 6 holds the electrode assembly 7.

[0030] Therefore, if Figure 1 and Figure 2 As shown, the foam 6 covers the X-axis + side end portion of the electrode assembly 7, the X-axis - side end portion of the electrode assembly 7, the Y-axis + side end portion of the electrode assembly 7, the Y-axis - side end portion of the electrode assembly 7, and the Z-axis - side end portion of the electrode assembly 7.

[0031] Here, if Figure 2 As shown, when viewed from the Z-axis direction, the circumferential shape formed by the X-axis + side surface, the X-axis - side surface, the Y-axis + side surface and the Y-axis - side surface in the foam body 6 is smaller than the inner circumferential shape of the circumferential side portion formed by the X-axis + side side, the X-axis - side side, the Y-axis + side side and the Y-axis - side side in the shell body 5a of the shell 5.

[0032] In addition, if Figure 1 and Figure 2 As shown, the distance between the X-axis + side surface and the X-axis - side surface in the foam body 6 is wider than the distance between the X-axis - side end of the X-axis + side convex portion 5b and the X-axis - side end of the X-axis + side convex portion 5b in the shell 5.

[0033] like Figure 1 and Figure 2 As shown, such a foam body 6 is inserted into the interior of the shell 5 from the open opening on the Z-axis + side of the shell 5 while maintaining the electrode assembly 7 inserted into the insertion part 6a of the foam body 6, and the corner on the Z-axis - side of the foam body 6 is embedded in the recess 5d of the retaining part 5c of the shell 5.

[0034] At this time, the electrode assembly 7 is held via the foam 6 by the convex portion 5 b and the holding portion 5 c of the case 5 , and the foam 6 is pressed toward the wound body 2 by the convex portion 5 b of the case 5 , thereby pressing the wound body 2 .

[0035] Next, the assembly process of the secondary battery 1 of this embodiment will be described. First, a wound body 2 is formed, and the positive electrode current collector 3 is electrically connected to the positive electrode of the wound body 2, and the negative electrode current collector 4 is electrically connected to the negative electrode of the wound body 2, thereby forming an electrode assembly 7. At this time, the positive electrode current collector 3 is already electrically connected to the positive electrode terminal provided on the cover, and the negative electrode current collector 4 is already electrically connected to the negative electrode terminal provided on the cover.

[0036] Next, the foam body 6 is formed into the above-described shape, and the electrode assembly 7 is inserted into the insertion portion 6a of the foam body 6. The foam body 6 holding the electrode assembly 7 is then inserted into the interior of the housing 5 through the opening on the Z-axis positive side of the housing 5, with the corner portion of the foam body 6 on the Z-axis negative side fitting into the recess 5d of the holding portion 5c of the housing 5.

[0037] At this time, since the convex portion 5 b of the case 5 extends in the Z-axis direction, which is the direction in which the foam 6 is inserted, the foam 6 can be smoothly inserted into the case 5 , and damage to the wound body 2 can be suppressed.

[0038] Afterwards, electrolyte is injected into the casing 5, and the opening on the Z-axis positive side of the casing 5 is covered with a cap. This completes the assembly of the secondary battery 1. Multiple secondary batteries 1 are arranged, for example, along the X-axis and electrically connected to form a battery module. Then, activation is performed while the sides of the battery module are restrained and the desired load is applied to the wound bodies 2 of each secondary battery 1.

[0039] At this time, the secondary battery 1 of this embodiment has the convex portion 5b formed on the case 5, so compared with the case where the convex portion 5b is not formed on the case 5, as shown in FIG. Figure 4 As shown, when the peripheral side portion of the battery module is constrained, a load can be satisfactorily applied to the secondary battery 1 with a small constraining force, thereby activating the secondary battery 1 .

[0040] Therefore, the secondary battery 1 of this embodiment can suppress the excessive load applied to the wound body 2 when a restraining force is applied to the circumferential side of the battery module in which the secondary batteries 1 are arranged, thereby preventing adverse effects on the wound body 2. Furthermore, the foam 6 can reduce the spring constant of the secondary battery compared to resin sheets, thereby improving the mountability of the secondary battery 1 in the battery module.

[0041] Furthermore, in the secondary battery 1 of this embodiment, the electrode assembly 7 is held by the convex portion 5 b and the holding portion 5 c of the case 5 via the foam 6 . Therefore, even if the secondary battery 1 is subjected to vibration or impact, damage to the wound body 2 can be suppressed.

[0042] In the secondary battery 1 of this embodiment, the convex portion 5b of the case 5 is formed into a rib shape when viewed from the Z-axis direction. Figure 5 In short, the convex portion 5b of the housing 5 may be any shape as long as it can press the wound body 2 through the foam 6.

[0043] The present disclosure is not limited to the above-described embodiment, and can be appropriately modified within a scope not departing from the gist of the present disclosure.

Claims

1. A secondary battery, characterized in that: have: A wound body is formed by winding a laminate of a positive electrode, a separator, and a negative electrode; a housing for housing the wound body; and The foam is disposed between the wound body and the shell and has insulating properties. A convex portion for pressing the wound body through the foam is formed on a side portion of the housing.

2. The secondary battery according to claim 1, wherein A holding portion for holding the foam body is formed at the bottom of the housing.

3. The secondary battery according to claim 1 or 2, characterized in that The protrusion is a rib extending in the insertion direction of the wound body into the case.

4. The secondary battery according to claim 1 or 2, characterized in that The foam is an independent foam type foam.

5. The secondary battery according to claim 1 or 2, characterized in that The convex portion presses the wound body through the foam when activating the secondary battery.

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