Secondary battery

Abstract

The present invention provides a secondary battery capable of applying a load to a wound body satisfactorily 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 is composed of 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 a general secondary battery, a load needs to be applied to the winding body when activating the secondary battery. However, since the winding body of a general secondary battery is surrounded by an insulator such as a porous elastic body, it is difficult to apply a good load to the winding body when activating the secondary battery. Summary of the invention

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

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

[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 above secondary battery, it is preferable that the protrusion is 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 body 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 It 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 the 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] The 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. In addition, in order to make the description clear, the following description and drawings are appropriately simplified. Here, in the following description, a three-dimensional (XYZ) coordinate system is used for explanation in order to make the description clear.

[0018] Figure 1 It 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 device is simplified by omitting 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 foamed body 6 .

[0020] The wound body 2 is formed by winding a stacked body in which a positive electrode, a separator, and a negative electrode are stacked. Figure 2 As shown, the wound body 2 is a substantially 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 + 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 disposed, for example, 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 may be made of aluminum, for example.

[0023] like Figure 1 and Figure 2 As shown, the housing body 5a is a bottomed cylinder shape with the Z-axis side blocked, for example, a generally rectangular shape that is long in the Y-axis direction when viewed from the Z-axis direction. The convex portion 5b is formed, for example, on the side portion on the X-axis + side and the side portion on the X-axis - side of the housing body 5a, and protrudes toward the inner side 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 5 b are arranged at substantially equal intervals in the Y-axis direction so as to be opposed to each other in the X-axis direction.

[0025] For example Figure 2 As shown, the convex portion 5b is roughly rectangular column shape when viewed from the Z-axis direction. At this time, the thickness of the convex portion 5b in the X-axis direction can be a thickness that can press the wound body 2 through the foam body 6, for example, preferably about 0.1mm to 1mm. However, the arrangement, number and shape of the convex portion 5b can be appropriately changed.

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

[0027] When the electrode assembly 7 held in the foam body 6 is inserted into the shell 5 and the electrolyte is injected, the opening of the shell 5 on the + side of the Z axis is covered by a cover not shown in the figure, 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) or the like.

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

[0030] Therefore, if Figure 1 and Figure 2 As shown, the foam 6 covers the X-axis + side end of the electrode assembly 7, the X-axis - side end of the electrode assembly 7, the Y-axis + side end of the electrode assembly 7, the Y-axis - side end of the electrode assembly 7 and the Z-axis - side end 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 surface on the X-axis + side, the surface on the X-axis - side, the surface on the Y-axis + side and the surface on the Y-axis - side in the foam body 6 is smaller than the inner circumferential shape of the circumferential side portion formed by the side on the X-axis + side, the side on the X-axis - side, the side on the Y-axis + side and the side on the Y-axis - side in the shell body 5a of the shell 5.

[0032] In addition, if Figure 1 and Figure 2 As shown, the interval between the surface on the X-axis + side and the surface on the X-axis - side in the foam body 6 is wider than the interval between the end on the X-axis - side of the convex portion 5b on the X-axis + side and the end on the X-axis + side of the convex portion 5b on the X-axis - side 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 portion 6a of the foam body 6, and the corner of the Z-axis - side of the foam body 6 is embedded in the recess 5d of the retaining portion 5c of the shell 5.

[0034] At this time, the electrode assembly 7 is held by 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 , so that the wound body 2 is pressed.

[0035] Next, the process of assembling the secondary battery 1 of the present embodiment is described. First, the wound body 2 is formed, the positive electrode collector 3 is electrically connected to the positive electrode of the wound body 2, and the negative electrode 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 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.

[0036] Next, the foam body 6 is formed into the above-mentioned shape, and the electrode assembly 7 is inserted into the insertion portion 6a of the foam body 6. Then, the foam body 6 holding the electrode assembly 7 is inserted into the interior of the housing 5 from the opening on the Z-axis + side of the housing 5, and the corner portion on the Z-axis - side of the foam body 6 is inserted into the recessed portion 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 insertion direction of the foam 6 , the foam 6 can be smoothly inserted into the case 5 , and damage to the wound body 2 can be suppressed.

[0038] After that, the electrolyte is injected into the housing 5, and the opening on the Z-axis + side of the housing 5 is covered with a cover, and the secondary battery 1 can be assembled. For example, a plurality of such secondary batteries 1 are arranged in the X-axis direction and electrically connected to each other to form a battery module. Then, the activation process is performed in a state where the peripheral side of the battery module is constrained and the required load is applied to the winding body 2 of each secondary battery 1.

[0039] At this time, since the secondary battery 1 of this embodiment has the protrusion 5b formed on the housing 5, compared with the case where the protrusion 5b is not formed on the housing 5, 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, and the secondary battery 1 can be activated.

[0040] Therefore, the secondary battery 1 of the present embodiment can suppress excessive load on the wound body 2 when a restraining force is applied to the peripheral side of the battery module in which the secondary batteries 1 are arranged, thereby avoiding adverse effects on the wound body 2. In addition, the foam body 6 can reduce the spring constant of the secondary battery and improve the mounting performance of the secondary battery 1 in the battery module compared to a resin sheet or the like.

[0041] In the secondary battery 1 of this embodiment, since 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 , damage to the wound body 2 can be suppressed even when the secondary battery 1 is subjected to vibration or impact.

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

[0043] The present disclosure is not limited to the above-described embodiments, 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, characterized in that: 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 an 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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