Terminals of a secondary battery

Abstract

This invention provides a terminal for a secondary battery in which the connection between the joining member and the member to be joined is less likely to come undone. [Solution] The terminal 1 of a secondary battery is characterized by comprising a metal joining member 10 and a metal member to be joined 20 to be joined to the joining member 10, wherein the joining member 10 and the member to be joined 20 are stacked vertically and pressure is applied to plastically deform the member to be joined 20, thereby fitting the joining member 10 and the member to be joined 20 together, the joining member 10 having a horizontal hole 15 extending laterally in the fitting portion with the member to be joined 20, and a part of the plastically deformed member to be joined 20 enters the horizontal hole 15, thereby fitting the joining member 10 and the member to be joined 20 together in a way that prevents them from being separated.

Description

Technical Field

[0001] The present invention relates to a terminal of a secondary battery formed by joining metal members to each other.

Background Art

[0002] Conventionally, as a terminal of a secondary battery formed by joining different metals to each other, the one shown in Patent Document 1 is known. In this terminal of the secondary battery, the central portion of the joined member made of an aluminum material flows into and is joined to a joined recess formed in the joining member by pressing a rod-shaped joining member made of a copper material and a plate-shaped joined member made of an aluminum material. Such a terminal of a secondary battery is used as a negative electrode terminal of a lithium ion battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional terminal of a secondary battery, the joining surfaces of the joining member and the joined member had a structure that was uniform in the circumferential direction. For this reason, when a force in the rotational direction was applied, there was a problem that the joining between the joining member and the joined member was likely to come off.

[0005] The present invention was created in view of the above problems, and an object thereof is to provide a terminal of a secondary battery in which the joining surfaces of the joining member and the joined member have a non-uniform structure in the circumferential direction, and the joining between the joining member and the joined member is difficult to come off even when a force in the rotational direction is applied.

Means for Solving the Problems

[0006] The present invention was created in view of the above problems, and is a terminal for a secondary battery having a metal joining member and a metal member to be joined to the joining member, wherein the joining member and the member to be joined are stacked in the vertical direction, and the joining member has a horizontal hole extending in the horizontal direction, and a part of the member to be joined enters the horizontal hole, thereby joining the joining member and the member to be joined in a way that prevents them from being separated. Furthermore, it is preferable that the joining member has higher rigidity than the member to be joined. Furthermore, it is preferable that the joining member has an annular projection into which the member to be joined fits, and that the lateral hole is formed in the annular projection. Furthermore, it is preferable that the joining member has a joining projection that protrudes toward the member to be joined, and that the lateral hole is formed in the joining projection. Furthermore, it is preferable that the joining member has a shaft portion in which the lateral hole is formed and a head portion which is wider than the shaft portion, and that the member to be joined covers the head portion of the joining member and a part of it penetrates the lateral hole. Furthermore, it is preferable that the joining member has a vertical hole extending from the joining surface with the member to be joined to the horizontal hole, and that the member to be joined passes through the vertical hole and enters the interior of the horizontal hole. [Effects of the Invention]

[0007] The terminals of the secondary battery of the present invention have a structure in which a portion of the member to be joined flows into a lateral hole formed in the joining member, resulting in a circumferentially non-uniform joint surface between the joining member and the member to be joined. Therefore, the joint surface of the joining member and the member to be joined has an anti-rotation effect and an anti-detachment effect, and has advantages such as being difficult to detach between the joining member and the member to be joined. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows the component shapes of the terminals of the secondary battery according to the present invention before joining them, where (a) is a side cross-sectional view showing the shape of the member to be joined, and (b) is a side cross-sectional view showing the shape of the joining member. [Figure 2] This is a side cross-sectional view showing the shape of the terminals of the secondary battery according to the present invention. [Figure 3] This is a side cross-sectional view showing a method for joining terminals of a secondary battery according to the present invention. [Figure 4] This is a side cross-sectional view showing the state after transitioning from Figure 3 to the next state. [Figure 5] This is a side cross-sectional view showing a second embodiment of the terminals of a secondary battery according to the present invention. [Figure 6] This is a side cross-sectional view showing a third embodiment of the terminals of a secondary battery according to the present invention. [Figure 7] This is a side cross-sectional view showing a fourth embodiment of the terminals of a secondary battery according to the present invention. [Figure 8] This is a side cross-sectional view showing a fifth embodiment of the terminals of a secondary battery according to the present invention. [Figure 9] This is a side cross-sectional view showing a joining method for a fifth embodiment of the terminals of a secondary battery according to the present invention. [Figure 10] This is a side cross-sectional view showing the state after transitioning from Figure 9 to the next state. [Figure 11] This is a side cross-sectional view showing a sixth embodiment of the terminals of a secondary battery according to the present invention. [Figure 12] This is a side cross-sectional view showing a joining method according to a sixth embodiment of the terminals of a secondary battery according to the present invention. [Figure 13] This is a side cross-sectional view showing the state after transitioning from Figure 12 to the next state. [Modes for carrying out the invention]

[0009] Hereinafter, a first embodiment of the terminal 1 of the secondary battery of the present invention will be described based on the drawings. FIGS. 1(a) and 1(b) show the materials of the terminal 1 of the secondary battery. By vertically overlapping a joining member 10 made of the copper material shown in FIG. 1(b) and a joined member 20 made of the aluminum material shown in FIG. 1(a) and performing pressure joining, the terminal 1 of the secondary battery shown in FIG. 2 is formed. These joining member 10 and joined member 20 are separately formed and prepared in advance, and are formed by, for example, cold forging or cutting.

[0010] The joining member 10 is composed of a flat head portion 11 and a shaft portion 12 integrally formed therewith. On the upper surface of the head portion 11, a bottomed joining recess 13 and an annular convex portion 14 located on the outer peripheral side of the joining recess 13 are provided.

[0011] The joining recess 13 is a pocket hole whose inner peripheral wall is formed in an inverted taper shape, and this inverted taper portion is inclined in a direction in which the joining recess 13 expands from the opening to the bottom.

[0012] The annular convex portion 14 has an outer peripheral surface continuous with the outer peripheral edge portion of the head portion 11, and a plurality of lateral holes 15 are formed at positions spaced apart by a predetermined interval in the circumferential direction.

[0013] The lateral hole 15 is a hole extending in the radial direction and penetrates from the inner peripheral surface to the outer peripheral surface of the annular convex portion 14.

[0014] The joined member 20 has a cylindrical shape, and its end portion 21 is formed to be sufficiently larger than the opening area of the joining recess 13 of the joining member 10. Further, a protrusion 22 that can be inserted into the joining recess 13 is formed at the end portion 21 of the joined member 20.

[0015] By joining these joining member 10 and joined member 20, the terminal 1 of the secondary battery shown in FIG. 2 is manufactured.

[0016] Figures 3 and 4 show the method of joining the joining member 10 and the member to be joined 20. The receiving mold 100 has a stepped insertion hole 101, and the head 11 of the joining member 10 is suspended from the stepped portion, and the shaft portion 12 of the joining member 10 is loosely fitted into the insertion hole 101, thereby holding the joining member 10 in the insertion hole 101.

[0017] Next, as shown in Figure 3, the end portion 21 of the member to be joined 20 is positioned so as to block the joining recess 13 of the joining member 10. Then, the punch pin 200 is advanced downwards, and the member to be joined 20 is compressed axially from the other end portion 23, causing the end portion 21 of the member to be joined 20 to flow due to plastic deformation. As a result, the end portion 21 of the member to be joined 20 fills the joining recess 13 of the joining member 10, and the joining member 10 and the member to be joined 20 are joined. At the time of joining, the member to be joined 20 is compressed until it becomes flat. As a result, the annular protrusion 14 of the joining member 10 is pressed radially outward by the flattened member to be joined 20 and inclined to widen towards the top. At this time, a part of the flattened member to be joined 20 enters the lateral hole 15.

[0018] As shown in Figure 4, once the joining is complete, the punch pin 200 is retracted upward and the knockout pin 102, located below the insertion hole 101 of the receiving mold 100, is advanced upward. This causes the terminal 1 of the secondary battery, formed by joining the joining member 10 and the member to be joined 20, to be ejected from the receiving mold 100.

[0019] As shown in Figure 3, the terminal 1 of the secondary battery manufactured by the above joining method has a joining projection 24 formed on the end 21 of the member to be joined 20 that is the same shape as the joining recess 13. Since the joining projection 24 catches on the joining recess 13 in the direction of removal, high removal strength is obtained. In addition, since the joining projection 24 of the member to be joined 20 is completely filled into the joining recess 13 of the joining member 10, high adhesion is obtained. Furthermore, during the pressurization process, a part of the member to be joined 20 (hereinafter referred to as the inflow portion 25) flows into the lateral hole 15 of the annular projection 14. Since this lateral hole 15 and the inflow portion 25 fit together firmly, the joining member 10 and the member to be joined 20 have an anti-dislodgement effect and an anti-rotation effect.

[0020] Terminal 1 of a secondary battery having such effects is suitable for use as the negative electrode terminal of a lithium-ion battery (not shown), for example, where the shaft portion 12 of the bonding member 10 is connected to a current collector plate (not shown) inside the lithium-ion battery, and the bonded member 20 is exposed to the outside of the lithium-ion battery and connected to a busbar (not shown). Since the terminal 1 of the secondary battery manufactured by the present invention is bonded with high adhesion, it has excellent electrical conductivity, and therefore, when used as the negative electrode terminal of a lithium-ion battery, the electrical resistance can be kept low.

[0021] The following describes the second to sixth embodiments as modifications of the present invention. These embodiments, like the first embodiment, consist of joining members 30, 40, 50, 60, and 70 made of copper material, in which the head portion 11 and the shaft portion 12 are integrally molded, and a member to be joined 20 made of aluminum material, which is joined to the joining members 30, 40, 50, 60, and 70.

[0022] The second embodiment is the terminal 1a of the secondary battery shown in Figure 5. The terminal 1a of this secondary battery has a bottomed joining recess 13 and an annular projection 14 located on the outer circumference side of the joining recess 13 on the upper surface of the head 11 of the joining member 30. Similar to the first embodiment, a lateral hole 15a is formed in the annular projection 14, passing through the annular projection 14 in the radial direction. The inlet 25a of the member to be joined 20 fits into this lateral hole 15a, so that the joining member 30 and the member to be joined 20 have an anti-rotation effect and an anti-detachment effect. Furthermore, in this second embodiment, the lateral hole 15a is inclined such that the outer circumference opening is located on the shaft side than the inner circumference opening. Therefore, when pressure joining is performed in the same way as in the first embodiment, the inclination of the lateral hole 15a makes it easier for the inlet 25a of the member to be joined 20 to flow into the lateral hole 15a. Furthermore, a joint projection 24 in the shape of a blind hole is formed at the end 21 of the member to be joined 20, which engages with the joint recess 13, and the interlocking of the joint projection 24 and the joint recess 13 provides an anti-loosening effect. With these structures, the joint member 30 and the member to be joined 20 have anti-loosening and anti-rotation effects, making it difficult for the joined surfaces to come apart.

[0023] The third embodiment is the terminal 1b of a secondary battery shown in Figure 6, in which a joining projection 16 is provided on the upper surface of the head 11 of the joining member 40, protruding toward the member to be joined 20. This joining projection 16 is configured in an inverse tapered shape, with its top protruding outward from the base, and this inverse tapered portion is inclined in a direction that widens the joining projection 16 as it moves from the base toward the top. In addition, a lateral hole 15b is formed in the joining projection 16, passing through it radially. As a result, when pressurized bonding is performed as in the first embodiment, the lateral hole 15b and the inlet 25b of the member to be joined that flows into the lateral hole 15b engage, so that the joining member 40 and the member to be joined 20 have an anti-rotation effect and an anti-detachment effect. Furthermore, a blind-shaped joint recess 26 is formed at the end 21 of the member to be joined 20, which engages with the joint projection 16. The interlocking of the joint recess 26 and the joint projection 16 provides an anti-detachment effect between the joining member 40 and the member to be joined 20. With this structure, the joint surface is less likely to come apart, and the joining member 40 and the member to be joined 20 are firmly joined.

[0024] The fourth embodiment is the terminal 1c of a secondary battery shown in Figure 7, in which the annular projection 14 and the joining projection 16 are provided on the upper surface of the head 11 of the joining member 50. The annular projection 14 and the joining projection 16 have the lateral holes 15a and 15b formed therein, respectively. Therefore, when pressurized bonding is performed as in the first embodiment, the lateral holes 15a and 15b engage with the inflow portions 25a and 25b of the member to be joined 20 that flow into these lateral holes 15a and 15b. As a result, the joining member 50 and the member to be joined 20 have an anti-rotation effect and an anti-detachment effect. In addition, a joint projection 24 in the shape of a blind hole is formed at the end 21 of the member to be joined 20, which engages with the joint recess 13, and the joint projection 24 and the joint recess 13 interlock to have an anti-detachment effect. With these structures, the joint surface is less likely to come apart and the joining member 50 and the member to be joined 20 are firmly joined.

[0025] The fifth embodiment is a terminal 1d of a secondary battery shown in Figure 8, in which a bottomed joining recess 13 is formed on the upper surface of the head 11 of the joining member 60, and a lateral hole 15c is provided near the head 11 of the shaft portion 12, passing through the shaft portion 12 radially. The inlet 25c of the member to be joined 20 flows into this lateral hole 15c, and the fitting of this lateral hole 15c and the inlet 25c provides an anti-rotation and anti-detachment effect for the joining member 60 and the member to be joined 20. The receiving mold 100 for forming the terminal 1d of this secondary battery has an insertion hole 101 that can hold the shaft portion 12 up to a certain point so as not to close the lateral hole 15c, as shown in Figure 9. This insertion hole 101 is configured to a depth that can accommodate the head 11 of the joining member 10 and the member to be joined 20 inside, and the punch pin 200 is inserted through it so as to be axially slidable. Therefore, as the punch pin 200 moves within the insertion hole 101, the member to be joined 20 undergoes plastic deformation as shown in Figure 10, covering the entire head 11 of the joining member 60, and a portion of it flows into the lateral hole 15c, so that the member to be joined 20 completely fills the joining recess 13 of the joining member 60 and the lateral hole 15c. By pressurizing the joining member 10 and the member to be joined 20 contained within the insertion hole 101 in this way, the joining member 60 and the member to be joined 20 have an anti-rotation and anti-detachment effect. As a result, the joining surface is less likely to come apart, and the joining member 60 and the member to be joined 20 are firmly joined. After joining, the punch pin 200 is retracted upward, and the knockout pin 102, located below the insertion hole 101 of the receiving mold 100, is advanced upward, thereby ejecting the terminals 1d of the secondary battery from the receiving mold 100.

[0026] The sixth embodiment is a terminal 1e of a secondary battery shown in Figure 11, in which a vertical hole 17 extending axially is formed on the upper surface of the joining member 70, and a horizontal hole 15d that penetrates to the outer circumference of the shaft portion 12 is continuous at the bottom of this vertical hole 17. The inlet portion 25d of the member to be joined 20 flows into this horizontal hole 15d, and the fitting of this horizontal hole 15d and the inlet portion 25d provides an anti-rotation effect and an anti-detachment effect for the joining member 70 and the member to be joined 20. As shown in Figure 12, the terminal 1e of this secondary battery is pressure-joined by a receiving mold 100 that holds the head portion 11 and shaft portion 12 of the joining member 70, and a punch pin 200 that presses the member to be joined 20 from above. During joining, the member to be joined 20 flows into the vertical hole 17 and horizontal hole 15d due to plastic deformation, and as shown in Figure 13, the member to be joined 20 fills the vertical hole 17 and horizontal hole 15c of the joining member 70. As a result, the joining member 70 and the member to be joined 20 have an anti-rotation effect and an anti-detachment effect, making it difficult for the joining surface to come apart, and thus the joining member 70 and the member to be joined 20 are firmly joined. Subsequently, by retracting the punch pin 200 upward and advancing the knockout pin 102 located below the insertion hole 101 of the receiving mold 100 upward, the terminal 1e of the secondary battery is discharged from the receiving mold 100.

[0027] The terminals 1a, 1b, 1c, 1d, and 1e of the secondary battery in the second to sixth embodiments described above are also suitable for use as the negative electrode terminals of a lithium-ion battery (not shown), in which the shaft portion 12 of the bonding member 70 is connected to a current collector plate (not shown) inside the lithium-ion battery, and the bonded member 20 is exposed to the outside of the lithium-ion battery and connected to a busbar (not shown).

[0028] It should be noted that the present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the invention. For example, in the above embodiments, the lateral holes 15, 15a, 15b, 15c, and 15d of the joining members 10, 30, 40, 50, 60, and 70 were all through holes penetrating in the lateral direction, but the invention is not limited to this, and may be bottomed holes formed to a predetermined depth. Also, the lateral holes 15, 15a, 15b, 15c, and 15d may be configured to be inclined in an oblique direction. Furthermore, although a projection 22 that is inserted into the joining recess 13 was formed on the end 21 of the member to be joined 20, there is no problem if it is configured as a flat surface without a projection 22. [Explanation of Symbols]

[0029] 1, 1a, 1b, 1c, 1d, 1e ... Terminals of a secondary battery 10, 30, 40, 50, 60, 70 ... Joining members 13… Joint recess 14 … Ring-shaped protrusion 15, 15a, 15b, 15c, 15d ... Horizontal cave 20 … Parts to be joined 24 ... Joint protrusion 25,25a,25b,25c,25d … Inflow part 100... Receiving type 101… Insertion hole 102… Knockout pin 200... Punch pin

Claims

1. A metal connecting member, It has a metal member to be joined to the aforementioned joining member, A terminal for a secondary battery in which the joining member and the joined member are fitted together by applying pressure to the joining member and the joined member which are stacked vertically, thereby causing plastic deformation of the joined member, The joining member has a lateral hole extending laterally in the fitting portion with the member to be joined, A terminal for a secondary battery, characterized in that a portion of the plastically deformed member to be joined enters the lateral hole, thereby ensuring that the joining member and the member to be joined are fitted together in a way that prevents them from being removed.

2. The terminal of the secondary battery according to claim 1, characterized in that the joining member has higher rigidity than the member to be joined.

3. The joining member has an annular projection formed thereon into which the member to be joined fits, The terminal of the secondary battery according to claim 1, characterized in that the lateral hole is formed in the annular protrusion.

4. The joining member has a joining projection that protrudes toward the member to be joined, The terminal of the secondary battery according to claim 1, characterized in that the aforementioned lateral hole is formed in the connecting protrusion.

5. The joining member has a shaft portion in which the lateral hole is formed and a head portion which is wider than the shaft portion. The terminal of the secondary battery according to claim 1, characterized in that the joined member covers the head of the joining member and a part of it penetrates the lateral hole.

6. The joining member has a vertical hole that extends from the joining surface with the member to be joined to the horizontal hole. The terminal of the secondary battery according to claim 1, characterized in that the member to be joined passes through the vertical hole and enters the interior of the horizontal hole.

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