Secondary batteries

Abstract

To provide a secondary battery that can favorably apply a load to a winding body when activating the secondary battery.SOLUTION: A secondary battery (1) includes a winding body (2) formed by winding a laminate of a positive electrode, a separator, and a negative electrode, a case (5) for accommodating the winding body (2), and an insulating foam body (6) disposed between the winding body (2) and the case (5). A protruding portion (5b) is formed on the side of the case (5) to press the winding body (2) through the foam body (6).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to secondary batteries. [Background technology]

[0002] A typical secondary battery such as a lithium ion battery is configured such that an insulator such as a porous elastic body is disposed between a wound body formed by winding a laminate formed by stacking a positive electrode, a separator, and a negative electrode, and a case that houses the wound body, as disclosed in Patent Document 1, for example. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6656624 Summary of the Invention [Problem to be solved by the invention]

[0004] The present applicant has found the following problem: In a typical secondary battery, a load needs to be applied to the wound body when activating the secondary battery. However, in a typical secondary battery, the wound body is surrounded by an insulator such as a porous elastic body, making it difficult to apply a load to the wound body properly when activating the secondary battery.

[0005] The present disclosure has been made in consideration of such problems, and provides a secondary battery that can effectively apply a load to the wound body when activating the secondary battery. [Means for solving the problem]

[0006] A secondary battery according to one embodiment of the present disclosure includes: a wound body obtained by winding a laminate formed by stacking a positive electrode, a separator, and a negative electrode; a case for accommodating the wound body; an insulating foam disposed between the wound body and the case; Equipped with A protrusion is formed on the side of the case to press the wound body via the foam.

[0007] In the secondary battery described above, it is preferable that a holding portion for holding the foam 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 in which the wound body is inserted into the case.

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

[0010] In the secondary battery described above, it is preferable that the protrusion presses the wound body via the foam when activating the secondary battery. [Effects of the Invention]

[0011] According to the present disclosure, a secondary battery can be realized that can effectively apply a load to the wound body when activating the secondary battery. [Brief explanation of the drawings]

[0012] [Figure 1] 2 is a cross-sectional view of the secondary battery according to the embodiment, viewed from the Y-axis − side. FIG. [Figure 2] 2 is a cross-sectional view of the secondary battery according to the embodiment, viewed from the +Z axis side. FIG. [Figure 3] 3A and 3B are diagrams illustrating a foam body in a secondary battery according to an embodiment. [Figure 4] 10 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. FIG. [Figure 5] FIG. 10 is a cross-sectional view of a secondary battery according to another embodiment, as viewed from the +Z axis side. DETAILED DESCRIPTION OF THE INVENTION

[0013] Specific embodiments to which the present disclosure is applied will be described in detail below with reference to the drawings. However, the present disclosure is not limited to the following embodiments. For clarity of explanation, the following description and drawings have been simplified as appropriate. Here, for clarity of explanation, the following description will be made using a three-dimensional (XYZ) coordinate system.

[0014] Fig. 1 is a cross-sectional view of the secondary battery of this embodiment as viewed from the negative Y-axis side. Fig. 2 is a cross-sectional view of the secondary battery of this embodiment as viewed from the positive Z-axis side. Fig. 3 is a diagram showing a foam in the secondary battery of this embodiment. Note that Figs. 1 and 2 are simplified by omitting terminals, a cover, etc. of the secondary battery.

[0015] The secondary battery 1 of this embodiment is, for example, a lithium-ion battery cell, and a plurality of secondary batteries form a battery module. As shown in Figures 1 and 2, 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 body 6.

[0016] The wound body 2 is formed by winding a laminate in which a positive electrode, a separator, and a negative electrode are stacked. As shown in Fig. 2, the wound body 2 has 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 + side of the Y-axis of the wound body 2.

[0017] 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 negative Y-axis side of the wound body 2. The wound body 2, the positive electrode current collector 3, and the negative electrode current collector 4 constitute an electrode assembly 7 as shown in FIGS.

[0018] 1 and 2, the case 5 houses the electrode assembly 7 and the foam 6 that covers 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.

[0019] 1 and 2, the case body 5a has a cylindrical shape with a closed bottom and a negative Z-axis side, and is, for example, a substantially rectangular shape that is long in the Y-axis direction when viewed from the Z-axis direction. The protrusions 5b are formed, for example, on the side portions of the case body 5a on the positive X-axis side and the negative X-axis side, and protrude toward the inside of the case body 5a.

[0020] 1, the protrusions 5b extend in the Z-axis direction and are arranged in a height region in the Z-axis direction where the wound body 2 is arranged. For example, as shown in FIG. 2, the protrusions 5b are arranged at approximately equal intervals in the Y-axis direction so as to face each other in the X-axis direction.

[0021] The protrusions 5b have a generally rectangular columnar shape when viewed from the Z-axis direction, as shown in Fig. 2. In this case, the thickness of the protrusions 5b in the X-axis direction may be such that they can press the wound body 2 via the foam 6, and may be, for example, about 0.1 to 1 mm. However, the arrangement, number, and shape of the protrusions 5b can be changed as appropriate.

[0022] 1 and 2, 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 negative side of the Z axis of the case body 5a, and recesses 5d into which the corners of the foam 6 are fitted are formed in the part of the holding portion 5c on the side of the foam 6.

[0023] In such a case 5, an electrode assembly 7 held by a foam 6 is inserted inside the case 5 and an electrolyte is poured into it. Then, the opening on the +Z axis side of the case 5 is covered with a cover (not shown), and the positive electrode current collector 3 is electrically connected to a positive electrode terminal provided on the cover, and the negative electrode current collector 4 is electrically connected to a negative electrode terminal provided on the cover.

[0024] 1 and 2, the foam 6 is disposed between the case 5 and the electrode assembly 7 to electrically insulate the case 5 from the electrode assembly 7. Therefore, as shown in FIG. 3, the foam 6 is a closed-cell foam, and is made of, for example, polypropylene (PP), polyethylene (PE), or polyurethane reactive (PUR).

[0025] 1 and 2, the foam 6 has a generally rectangular shape that is long in the Y-axis direction when viewed from the Z-axis direction, and extends in the Z-axis direction. The foam 6 has an insertion portion 6a into which the electrode assembly 7 is inserted, and the foam 6 holds the electrode assembly 7 when the electrode assembly 7 is inserted into the insertion portion 6a.

[0026] Therefore, as shown in Figures 1 and 2, the foam 6 covers the end of the electrode assembly 7 on the +X-axis side, the end of the electrode assembly 7 on the -X-axis side, the end of the electrode assembly 7 on the +Y-axis side, the end of the electrode assembly 7 on the -Y-axis side, and the end of the electrode assembly 7 on the -Z-axis side.

[0027] Here, when viewed from the Z-axis direction, the peripheral shape formed by the X-axis positive side surface, the X-axis negative side surface, the Y-axis positive side surface, and the Y-axis negative side surface of foam 6 is smaller than the inner peripheral shape of the peripheral side portion formed by the X-axis positive side side portion, the X-axis negative side side portion, the Y-axis positive side side portion, and the Y-axis negative side side of case body 5a of case 5, as shown in Figure 2.

[0028] Furthermore, as shown in Figures 1 and 2, the distance between the surface of foam 6 on the +X-axis side and the surface on the -X-axis side is wider than the distance between the end of the -X-axis side of the convex portion 5b on the +X-axis side facing each other in case 5 and the end of the +X-axis side of the convex portion 5b on the -X-axis side.

[0029] As shown in Figures 1 and 2, such a foam 6 is inserted into the case 5 from the opening on the +Z-axis side of the case 5 while holding the electrode assembly 7 inserted into the insertion portion 6a of the foam 6, and the corner of the foam 6 on the -Z-axis side is fitted into the recess 5d of the holding portion 5c of the case 5.

[0030] At this time, the electrode assembly 7 is held via the foam 6 by the convex portion 5b and holding portion 5c of the case 5, and the foam 6 is pressed toward the wound body 2 by the convex portion 5b of the case 5, resulting in the wound body 2 being pressed.

[0031] Next, the procedure for assembling the secondary battery 1 of this embodiment will be described. First, the wound body 2 is formed, and then 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 the electrode assembly 7. At this time, the positive electrode current collector 3 is electrically connected in advance to a positive electrode terminal provided on the cover, and the negative electrode current collector 4 is electrically connected to a negative electrode terminal provided on the cover.

[0032] Next, the foam 6 is formed into the above-mentioned shape, and the electrode assembly 7 is inserted into the insertion portion 6a of the foam 6. Then, the foam 6 holding the electrode assembly 7 is inserted into the case 5 from the opening on the +Z axis side of the case 5, and the corner of the foam 6 on the -Z axis side is fitted into the recessed portion 5d of the holding portion 5c of the case 5.

[0033] At this time, since the protrusion 5b 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.

[0034] Thereafter, an electrolyte solution is poured into the case 5, and the opening on the +Z-axis side of the case 5 is covered with a cover, thereby assembling the secondary battery 1. A plurality of such secondary batteries 1 are arranged, for example, in the X-axis direction and electrically connected to each other to form a battery module. Then, the periphery of the battery module is restrained, and an activation process is carried out with a desired load applied to the wound body 2 of each secondary battery 1.

[0035] In this case, since the secondary battery 1 of this embodiment has a protrusion 5b formed on the case 5, a load can be applied to the secondary battery 1 effectively with a small restraining force when restraining the peripheral side of the battery module, as shown in Figure 4, compared to when the protrusion 5b is not formed on the case 5, thereby activating the secondary battery 1.

[0036] Therefore, the secondary battery 1 of this embodiment can prevent excessive loads that would adversely affect the wound body 2 when a restraining force is applied to the periphery of a battery module in which secondary batteries 1 are arranged. Furthermore, compared to a resin sheet or the like, the foam 6 can reduce the spring constant of the secondary battery, improving the mountability of the secondary battery 1 in the battery module.

[0037] Furthermore, in the secondary battery 1 of this embodiment, the electrode assembly 7 is held via the foam 6 by the convex portion 5b and the holding portion 5c of the case 5, so that damage to the wound body 2 can be suppressed even if the secondary battery 1 is subjected to vibration or impact.

[0038] In the secondary battery 1 of the present embodiment, the protrusions 5b of the case 5 are formed in a rib shape when viewed from the Z-axis direction, but may also be formed in a dowel shape as shown in Fig. 5. In short, the protrusions 5b of the case 5 may have any shape as long as they can press the wound body 2 via the foam 6.

[0039] The present disclosure is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the present disclosure. [Explanation of symbols]

[0040] 1 Secondary battery 2 wound body 3 Positive electrode current collector 4 Negative electrode current collector 5 case, 5a case body, 5b convex portion, 5c holding portion, 5d concave portion 6 foam, 6a insert 7 Electrode assembly

Claims

1. a wound body obtained by winding a laminate of a positive electrode, a separator, and a negative electrode; a case for accommodating the wound body; an insulating foam disposed between the wound body and the case; Equipped with A secondary battery, wherein a protrusion is formed on a side of the case to press the wound body via the foam.

2. The secondary battery according to claim 1 , wherein a holding portion for holding the foam is formed on the bottom of the case.

3. The secondary battery according to claim 1 , wherein the protrusion is a rib extending in an insertion direction in which the wound body is inserted into the case.

4. The secondary battery according to claim 1 , wherein the foam is a closed-cell foam.

5. The secondary battery according to claim 1 , wherein the protrusion presses the wound body via the foam when the secondary battery is activated.

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