Manufacturing method of secondary battery

Abstract

To provide a manufacturing method of a secondary battery which contributes to downsizing of a restriction mechanism for introducing a restriction force to an electrode body of a secondary battery.SOLUTION: A manufacturing method of a secondary battery (1) configured by storing an electrode body (2) including a positive electrode and a negative electrode inside of a case (3) includes the steps of: inserting the electrode body (2) into the case (3) in a state where a width dimension (W3) of an opening of the case (3) is formed wide with respect to a width dimension (W2) of the electrode body (2) and the width dimension (W2) of the electrode body (2) is wide with respect to a width dimension (W4) of a lid (4) which covers the opening of the case (3); and fixing the lid (4) to the opening of the case (3) in a state where the case (3) is compressed in a width direction of the case (3) and the electrode body (2) is restricted by the case (3).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a secondary battery in which an electrode assembly having a positive electrode and a negative electrode is housed inside a case. [Background technology]

[0002] A typical secondary battery such as a lithium-ion battery is configured such that an electrode assembly having a positive electrode and a negative electrode is housed inside a case. In this case, the secondary battery of Patent Document 1 is configured such that a rib structure is formed on the case to press the electrode assembly when a restraining force is applied from the outside, in order to prevent the electrode assembly from shifting due to vibration. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-45365 Summary of the Invention [Problem to be solved by the invention]

[0004] The present applicant has found the following problem: The secondary battery of Patent Document 1 does not have a configuration that allows the secondary battery itself to restrain the electrode assembly without the introduction of an external restraining force. Therefore, it is necessary to restrain the electrode assembly of the secondary battery using a large-scale external restraining mechanism.

[0005] The present disclosure has been made in consideration of such problems, and realizes a method for manufacturing a secondary battery that contributes to miniaturization of a restraining mechanism for introducing a restraining force into an electrode body of the secondary battery. [Means for solving the problem]

[0006] A method for manufacturing a secondary battery according to one embodiment of the present disclosure is a method for manufacturing a secondary battery in which an electrode assembly having a positive electrode and a negative electrode is housed inside a case, the method comprising: a step of inserting the electrode body into the case in a state in which the width dimension of the opening of the case is formed wider than the width dimension of the electrode body and the width dimension of the electrode body is wider than the width dimension of a lid that covers the opening of the case; a step of compressing the case in a width direction of the case to restrain the electrode body with the case, and fixing the lid to the opening of the case; Equipped with.

[0007] In the method for manufacturing the secondary battery described above, it is preferable that, before the case is compressed, the width dimension of the case widens toward the opening of the case so that the bottom side portion of the case can accommodate the bottom side portion of the electrode body when the electrode body is placed on the bottom of the case.

[0008] In the method for manufacturing a secondary battery described above, it is preferable that the width of the bottom of the case before the case is compressed is narrower than the width of the electrode assembly.

[0009] In the above-described method for manufacturing a secondary battery, the width direction of the secondary battery is preferably the same as the stacking direction of the secondary batteries when the secondary batteries are stacked to form a battery pack. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to realize a method for manufacturing a secondary battery that contributes to miniaturization of a restraining mechanism for introducing a restraining force into an electrode body of the secondary battery. [Brief explanation of the drawings]

[0011] [Figure 1] 4 is a simplified YZ cross-sectional view showing a state before an electrode body is inserted into a case and a lid is fixed to an opening of the case in a method for manufacturing a secondary battery according to an embodiment. FIG. [Figure 2] 4 is a YZ cross-sectional view showing, in a simplified manner, how the electrode body is inserted into the case and the lid is fixed to the opening of the case in the method for manufacturing the secondary battery according to the embodiment. FIG. [Figure 3] 4 is a simplified YZ cross-sectional view showing a state after an electrode body is inserted into a case and a lid is fixed to an opening of the case in a manufacturing method of a secondary battery according to an embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] 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.

[0013] First, the configuration of each component before the case containing the electrode body is compressed will be described in the method for manufacturing a secondary battery of this embodiment. Fig. 1 is a YZ cross-sectional view showing, in a simplified manner, a state before the electrode body is inserted into the case and the lid is fixed to the opening of the case in the method for manufacturing a secondary battery of this embodiment. Fig. 2 is a YZ cross-sectional view showing, in a simplified manner, a state when the electrode body is inserted into the case and the lid is fixed to the opening of the case in the method for manufacturing a secondary battery of this embodiment.

[0014] Fig. 3 is a YZ cross-sectional view showing a simplified state after the electrode body is inserted into the case and the lid is fixed to the opening of the case in the manufacturing method of the secondary battery of the present embodiment. Note that in Figs. 1 to 3, the electrode body and the case before compression are shown by solid lines, and the lid and the case after compression are shown by dashed lines. Also, in Fig. 3, the electrode body before compression is shown by virtual lines.

[0015] The secondary battery 1 of this embodiment is, for example, a lithium ion battery cell, and a battery pack is made up of a plurality of secondary batteries 1. As shown in Figures 1 to 3, the secondary battery 1 includes an electrode body 2, a case 3, and a lid 4.

[0016] The electrode assembly 2 includes a long sheet-shaped positive electrode, a long sheet-shaped negative electrode, and a separator. The electrode assembly 2 is formed, for example, by winding a stack of a positive electrode, a separator, and a negative electrode. The electrode assembly 2 has a longitudinal direction, for example, in the X-axis direction, and the positive electrode current collector and the negative electrode current collector of the electrode assembly 2 are arranged with a gap in the X-axis direction. Note that the electrode assembly 2 may be any electrode assembly used in a general secondary battery, and is not an essential part of the present disclosure, so detailed description thereof will be omitted.

[0017] 1 to 3, the case 3 has a cylindrical shape with a bottom and a closed negative side in the Z-axis direction. That is, the case 3 has a bottom 3a, a first side wall 3b, a second side wall 3c, and third and fourth side walls (not shown). The bottom 3a is, for example, a plate-like portion substantially parallel to the XY plane and has a substantially rectangular shape with its longitudinal axis in the X-axis direction.

[0018] The width dimension W1 in the Y-axis direction of the bottom 3a is narrower than the width dimension W2 in the Y-axis direction of the electrode body 2 before the case 3 containing the electrode body 2 is compressed, as shown in Figure 1 (for example, the width dimension W2 in the Y-axis direction of the part of the electrode body 2 that bulges most in the Y-axis direction).

[0019] The length of the bottom 3a in the X-axis direction may be longer than the length of the electrode body 2 in the X-axis direction before the case 3 in which the electrode body 2 is housed is compressed, taking into account that the electrode body 2 is pushed out in the X-axis direction when the case 3 in which the electrode body 2 is housed is compressed in the Y-axis direction.

[0020] 1 to 3, the first side wall 3b extends from the end of the bottom 3a on the +Y-axis side toward the +Z-axis side. The first side wall 3b is, for example, a substantially rectangular shape when viewed from the Y-axis direction, and is a plate-like portion having an inclined portion 3b1 that inclines toward the +Y-axis side as it approaches the +Z-axis side, and a flat portion 3b2 that extends toward the +Z-axis side from the end of the inclined portion 3b1 on the +Z-axis side.

[0021] 1 to 3, the second side wall 3c extends from the end of the bottom 3a on the negative side of the Y axis to the positive side of the Z axis. When viewed from the X axis direction, for example, the second side wall 3c is in a line-symmetric relationship with the first side wall 3b, with the axis of symmetry passing through the center of the case 3 in the Y axis direction and extending in the Z axis direction, and is a plate-like portion having an inclined portion 3c1 and a flat portion 3c2.

[0022] In other words, the inclined portion 3b1 of the first side wall portion 3b and the inclined portion 3c1 of the second side wall portion 3c are widened toward the +Z-axis side so that the -Z-axis side portion of the electrode body 2 can be accommodated when the electrode body 2 is inserted inside the case 3 and placed on the bottom 3a.

[0023] The third sidewall extends from the end of the bottom 3a on the +X-axis side toward the +Z-axis side and closes the opening on the +X-axis side formed by the bottom 3a, the first sidewall 3b, and the second sidewall 3c. The fourth sidewall extends from the end of the bottom 3a on the -X-axis side toward the +Z-axis side and closes the opening on the -X-axis side formed by the bottom 3a, the first sidewall 3b, and the second sidewall 3c.

[0024] The width dimension W3 in the Y-axis direction of the opening on the positive side of the Z-axis of such case 3 is wider than the width dimension W2 in the Y-axis direction of the electrode body 2 before the case 3 containing the electrode body 2 is compressed. The internal height H1 of the case 3 may be such that the entire electrode body 2 can be housed inside the case 3 when the case 3 containing the electrode body 2 is compressed.

[0025] 1 to 3, the lid 4 is a plate-like portion that is approximately parallel to the XY plane and has approximately the same shape as the bottom 3a of the case 3 when viewed from the Z-axis direction. Therefore, the width dimension W4 of the lid 4 in the Y-axis direction is also narrower than the width dimension W2 of the electrode assembly 2 in the Y-axis direction before the case 3 containing the electrode assembly 2 is compressed. Although not shown, the lid 4 is provided with a positive electrode terminal and a negative electrode terminal that are electrically connected to the positive electrode current collector and negative electrode current collector of the electrode assembly 2, respectively.

[0026] Next, a method for manufacturing the secondary battery 1 of this embodiment will be described. First, as shown in Fig. 1, the electrode body 2 is inserted into the case 3. At this time, gaps are formed between the end of the electrode body 2 on the +Y-axis side and the first side wall 3b of the case 3, and between the end of the electrode body 2 on the -Y-axis side and the second side wall 3c of the case 3.

[0027] Then, the lid 4 is placed on the +Z-axis side of the electrode body 2, and the positive electrode terminal provided on the lid 4 is electrically connected to the positive electrode current collector of the electrode body 2, and the negative electrode terminal provided on the lid 4 is electrically connected to the negative electrode current collector of the electrode body 2.

[0028] Next, as shown in Fig. 2, the case 3 containing the electrode body 2 is compressed in the Y-axis direction to restrain the electrode body 2 between the first side wall 3b and the second side wall 3c of the case 3. In this state, the lid 4 is fixed to the opening on the +Z-axis side of the case 3 by welding or the like, and the opening on the +Z-axis side of the case 3 is closed as shown in Fig. 3. This places the electrode body 2 in a state where it is restrained by the case 3 with a predetermined restraining force.

[0029] Thereafter, for example, an electrolyte solution is filled inside the case 3, thereby manufacturing the secondary battery 1. Then, such secondary batteries 1 are stacked in the Y-axis direction, which is the compression direction of the secondary batteries 1, and the positive electrode terminals of adjacent secondary batteries 1 are electrically connected to the negative electrode terminals of the secondary batteries 1 by a bus bar, and the stacked secondary batteries 1 are restrained by a restraining mechanism, thereby forming an assembled battery.

[0030] In this case, since the secondary battery 1 is configured so that the secondary battery 1 itself can restrain the electrode body 2, the restraining force introduced by the restraining mechanism can be reduced, which can contribute to making the restraining mechanism smaller.

[0031] In this way, the manufacturing method of the secondary battery 1 of this embodiment is configured so that the secondary battery 1 itself can restrain the electrode body 2, so that the restraining force introduced by the restraining mechanism is small, which can contribute to making the restraining mechanism smaller.

[0032] The present disclosure is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the present disclosure. For example, the shape of the case 3 in the above embodiment is merely an example, and any shape may be used as long as it can accommodate the electrode body 2 before being compressed and can restrain the electrode body 2 after the case 3 is compressed. For example, in the above embodiment, the stacked secondary batteries 1 are restrained by a restraining mechanism when forming a battery pack, but the restraining mechanism may be omitted. Also, the secondary batteries 1 may be used alone without forming a battery pack. For example, in the above embodiment, before the case 3 containing the electrode body 2 is compressed from the Y-axis direction to restrain the electrode body 2 between the first side wall portion 3b and the second side wall portion 3c of the case 3, the positive electrode terminal provided on the lid 4 is electrically connected to the positive electrode collector of the electrode body 2, and the negative electrode terminal provided on the lid 4 is electrically connected to the negative electrode collector of the electrode body 2, but this may also be done after the electrode body 2 is restrained. [Explanation of symbols]

[0033] 1 Secondary battery 2 Electrode body 3 Cases 3a bottom 3b first side wall part, 3b1 sloped part, 3b2 flat part 3c second side wall portion, 3c1 inclined portion, 3c2 flat portion 4 Lid W1 Width dimension of the bottom of the case in the Y-axis direction W2 Width of the electrode body in the Y-axis direction W3 Width dimension in the Y-axis direction of the opening on the Z-axis + side of the case W4 Width of the lid in the Y-axis direction

Claims

1. A method for manufacturing a secondary battery in which an electrode assembly having a positive electrode and a negative electrode is housed inside a case, a step of inserting the electrode body into the case in a state in which the width dimension of the opening of the case is formed wider than the width dimension of the electrode body and the width dimension of the electrode body is wider than the width dimension of a lid that covers the opening of the case; a step of compressing the case in a width direction of the case to restrain the electrode body with the case, and fixing the lid to the opening of the case; A method for manufacturing a secondary battery comprising the steps of:

2. 2. The method for manufacturing a secondary battery according to claim 1, wherein, before the case is compressed, the width dimension of the case widens toward the opening of the case so that the bottom side portion of the case can accommodate the electrode body placed on the bottom of the case.

3. The method for manufacturing a secondary battery according to claim 1 or 2, wherein a width dimension of the bottom of the case before the case is compressed is narrower than a width dimension of the electrode body.

4. 3. The method for manufacturing a secondary battery according to claim 1, wherein a width direction of the secondary battery is the same as a stacking direction of the secondary batteries when the secondary batteries are stacked to form a battery pack.

Images