Stacked battery

Abstract

The objective is to provide a stacked battery capable of suppressing damage to the current collector connecting the power generation element and the electrode tab. [Solution] The stacked battery 10 is a stacked battery 10 that includes a stacked body 26 in which a plurality of power generation elements 24, including a positive electrode 20 and a negative electrode 22, are stacked. The stacked battery 10 includes current collectors (30, 36) that extend from the positive electrode 20 and the negative electrode 22 and are grouped together as a plurality of divided bundles (40, 42, 44, 46) at each electrode 20, 22, and a pair of electrode tabs 50 to which the current collectors (30, 36) of each electrode 20, 22 are joined. The electrode tab 50 has a base end 52 and a tip 58 that bends from the base end 52 via a bending portion 54 and extends along the stacking direction 56, and at least one of the plurality of divided bundles (40, 42, 44, 46) is joined to the surface (70) of the tip 58 on the stacked body 26 side.

Description

Technical Field

[0001] The present invention relates to a laminated battery.

Background Art

[0002] Patent Document 1 discloses a lithium-ion secondary battery. The lithium-ion secondary battery constitutes a laminated battery.

[0003] The lithium-ion secondary battery has a plurality of power generation elements including a negative electrode, a separator, and a positive electrode laminated. The current collectors extending from each electrode are joined to electrode tabs constituting a terminal plate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the lithium-ion secondary battery described in Patent Document 1, since the current collector joined to the electrode tab extends across the edge of the tip of the electrode tab, there is a risk of interference with the edge of the electrode tab and damage.

[0006] An object of the present invention is to provide a laminated battery capable of suppressing damage to a current collector connecting a power generation element and an electrode tab.

Means for Solving the Problems

[0007] A stacked battery according to one aspect of the present invention is a stacked battery comprising a stack in which a plurality of power generation elements, including a positive electrode and a negative electrode, are stacked. The stacked battery comprises current collectors extending from the positive electrode and the negative electrode and grouped together as a plurality of divided bundles at each electrode, and a pair of electrode tabs to which the current collectors of each electrode are joined. The electrode tabs comprise a base end and a tip end that bends from the base end via a bending portion and extends along the stacking direction, and at least one of the plurality of divided bundles is joined to the stacked surface of the tip end. [Effects of the Invention]

[0008] According to one aspect of the present invention, the electrode tab to which the current collector is joined has a bent portion, and the tip portion on the tip side of the bent portion extends along the lamination direction of the laminate. At least one of the divided bundles of current collectors extending from the power generation element of the laminate is joined to the laminate-side surface of the tip portion.

[0009] Thus, since the electrode tab having a bent portion has a surface facing the laminate side, the divided bundle of current collectors joined to the surface facing the laminate side does not cross the edge of the electrode tab tip, and the electrode tab is joined. For this reason, the laminated battery can suppress damage to the current collector connecting the power generation element and the electrode tab compared to cases where the current collector may interfere with the edge of the electrode tab tip. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is an exploded perspective view showing a stacked battery according to an embodiment of the present invention. [Figure 2] Figure 2 is a side view showing a disassembled stacked battery. [Figure 3] Figure 3 is a side view showing the main components of a stacked battery removed from its case. [Figure 4] Figure 4 is a process diagram showing the procedure for joining the current collector to the electrode tab. [Figure 5] Figure 5 is a side view showing the main parts of a stacked battery according to the first modified example. [Figure 6]Figure 6 is a side view showing the main parts of a stacked battery according to the second modified example. [Figure 7] Figure 7 is a side view showing the main parts of a stacked battery according to the third modified example. [Figure 8] Figure 8 is a side view showing the main parts of a stacked battery according to the fourth modified example. [Figure 9] Figure 9 is a side view showing the main parts of a stacked battery according to the fifth modified example. [Modes for carrying out the invention]

[0011] <Embodiment> Embodiments of the present invention will be described below with reference to the drawings.

[0012] Figure 1 is an exploded perspective view showing a stacked battery 10 according to an embodiment of the present invention. Figure 2 is a side view showing the stacked battery 10 in a disassembled state. Figure 3 is a side view showing the main parts of the stacked battery 10 removed from the package, showing only the positive electrode 20 side of the stacked battery 10.

[0013] The stacked battery 10 according to this embodiment is used, for example, in an electric vehicle. This stacked battery 10 is composed of a rechargeable secondary battery. Examples of secondary batteries include lithium-ion batteries and all-solid-state batteries. The stacked battery 10 of this embodiment is composed of a lithium deposition type all-solid-state battery.

[0014] As shown in Figures 1 and 2, the package of the stacked battery 10 consists of a first case 2 and a second case 4. The stacked structure 26 that constitutes the stacked battery 10 is housed between the first case 2 and the second case 4.

[0015] (Laminated structure) As shown in Figure 3, the stacked battery 10 comprises a stacked body 26 in which multiple power generation elements 24, including a positive electrode 20 and a negative electrode 22, are stacked.

[0016] Between the positive electrode 20 and the negative electrode 22 that constitute the power generation element 24 of the laminate 26, for example, a solid electrolyte layer 28 is laminated. A positive electrode current collector 30 as a current collector is laminated on the positive electrode 20 of the power generation element 24. The positive electrode current collector 30 is electrically connected to the positive electrode 20, and from the positive electrode 20, the positive electrode current collector 30 extends toward one side 32 of the laminate 26.

[0017] A negative electrode current collector 36 as a current collector is laminated on the negative electrode 22 of the power generation element 24. The negative electrode current collector 36 is electrically connected to the negative electrode 22, and from the negative electrode 22, the negative electrode current collector 36 extends toward the other side (not shown) of the laminate 26.

[0018] (Current collector) The laminated battery 10 includes current collectors (30, 36) that extend from the positive electrode 20 and the negative electrode 22 and are grouped as a plurality of divided bundles (40, 42, 44, 46) at each of the electrodes 20, 22.

[0019] Each of the current collectors 30, 36 extending from each of the electrodes 20, 22 is bundled at a predetermined number, and each of the bundled current collectors 30, 36 forms a divided bundle (40, 42, 44, 46).

[0020] The current collectors 30, 36 of the present embodiment are divided into four: a first divided bundle 40, a second divided bundle 42, a third divided bundle 44, and a fourth divided bundle 46, which are formed by bundling a predetermined number of positive electrode current collectors 30 (only the positive electrode current collector side is shown).

[0021] In addition, although only the positive electrode current collector 30 is shown in FIG. 3, the negative electrode current collector 36 is configured in the same manner as the positive electrode current collector 30.

[0022] (Electrode tab) The laminated battery 10 includes a pair of electrode tabs 50 (only the electrode tab 50 on the positive electrode 20 side is shown) to which the current collectors 30, 36 of each of the electrodes 20, 22 are joined. That is, the positive electrode current collector 30 of the positive electrode 20 is connected to the electrode tab 50 on the positive electrode side, and the negative electrode current collector 36 of the negative electrode 22 is connected to the electrode tab 50 on the negative electrode side. The electrode tab 50 includes a base end portion 52 and a tip end portion 58 that bends from the base end portion 52 via a bent portion 54 and extends along the lamination direction 56.

[0023] The electrode tabs 50 are terminals for drawing electricity from the laminate 26. The electrode tabs 50 on one side 32 of the laminate 26 constitute the positive electrode terminal to which the positive electrode current collector 30 is connected. The electrode tabs 50 on the other side of the laminate 26 constitute the negative electrode terminal (not shown).

[0024] The electrode tab 50 is made of a metal plate that extends in a cross direction 60 which is substantially the same direction as the extending direction of the power generation element 24 of the laminate 26 and intersects with the stacking direction 56 of the laminate 26. The electrode tab 50 has a bent portion 54 on the tip side closer to the laminate 26 that is bent along the stacking direction 56 of the laminate 26.

[0025] As a result, the electrode tab 50 is divided into a tip portion 58 that forms the tip side with respect to the bending portion 54 and extends in the stacking direction 56, and a base portion 52 that forms the base side with respect to the bending portion 54 and extends in the intersecting direction 60. The tip portion 58 extends approximately perpendicular to the base portion 52. In other words, the tip portion 58 extends in the bending direction.

[0026] The outer surface constituting the outer periphery of the bent portion 54 is composed of a smooth curved surface. As a result, the outer surface of the bent portion 54 does not have any sharp corners.

[0027] This bent portion 54 creates two surfaces on the plate-shaped electrode tab 50: one facing the laminate 26 and the other facing the laminate 26. The surface of the electrode tab 50 facing the laminate 26 constitutes a bonding surface 70 to which the current collectors 30 and 36 are joined. The surface opposite the bonding surface 70 constitutes a non-bonding surface 72 to which the current collectors 30 and 36 are not joined.

[0028] The bonding surface 70 of the electrode tab 50 is provided with a first bonding location 80 to which the first divided bundle 40 is bonded, a second bonding location 82 to which the second divided bundle 42 is bonded, a third bonding location 84 to which the third divided bundle 44 is bonded, and a fourth bonding location 86 to which the fourth divided bundle 46 is bonded.

[0029] The first bonding point 80 and the second bonding point 82 are set at the tip 58 of the electrode tab 50, and the first split bundle 40 and the second split bundle 42 are bonded to the tip 58.

[0030] As a result, at least one of the multiple divided bundles (40, 42, 44, 46) is joined to the joining surface 70, which is the surface of the tip portion 58 facing the laminate 26. In addition, two or more divided bundles (40, 42) are joined to the tip portion 58 at different locations.

[0031] Furthermore, the third and fourth bonding points 84 and 86 are set at the proximal end 52 of the electrode tab 50, and the third and fourth split bundles 44 and 46 are bonded to the proximal end 52.

[0032] As a result, one of the multiple divided bundles (40, 42, 44, 46) is joined to the base end 52. In addition, two or more divided bundles (44, 46) are joined to the base end 52 at different locations.

[0033] Although Figure 3 only shows the electrode tab 50 of the positive electrode 20 to which the positive electrode current collector 30 is attached, the electrode tab 50 of the negative electrode 22 to which the negative electrode current collector 36 is attached is configured in the same way as the electrode tab 50 of the positive electrode 20.

[0034] (Manufacturing method) Figure 4 is a process diagram showing the procedure for joining the current collectors (30, 36) to the electrode tabs 50. Figure 4 shows how the positive electrode current collector 30 is joined to the electrode tab 50 of the positive electrode 20, but the negative electrode current collector 36 is joined to the electrode tab 50 of the negative electrode 22 using a similar process.

[0035] When joining the current collectors (30, 36) to the electrode tabs 50, in the first step 100, the worker joins the second divided bundle 42 to the second joining point 82 of the electrode tabs 50 using an ultrasonic bonding device, with the tip portion 58 of the electrode tabs 50 extending in a crossing direction 60 that intersects the stacking direction 56.

[0036] To explain the joining method in detail, the worker places the second divided bundle 42, which is made up of bundled positive electrode current collectors 30, at the second joining point 82 on the bent portion 54 side of the tip 58 of the electrode tab 50, so that the tip 42A faces the tip side of the electrode tab 50. In this position, the worker supports the tip 58 of the electrode tab 50 from below with the anvil 110 of the ultrasonic joining device. Then, the worker vibrates the horn 112 of the ultrasonic joining device and brings it into contact with the second divided bundle 42, while simultaneously applying pressure to the second divided bundle 42 toward the anvil 110, thereby joining the second divided bundle 42 to the second joining point 82.

[0037] Furthermore, in the second step 102, the worker joins the first divided bundle 40 to the first joining point 80 of the electrode tab 50 in the same manner as described above. Then, in the third step 104, the worker rotates the electrode tab 50 by 90 degrees, so that the tip portion 58 of the electrode tab 50 is facing upward and the base portion 52 extends in the intersecting direction 60.

[0038] Next, in the fourth step 106, the worker joins the third divided bundle 44 to the third joint location 84 of the electrode tab 50 in the same manner as described above, and in the fourth step 108, the worker joins the fourth divided bundle 46 to the fourth joint location 86 of the electrode tab 50 in the same manner as described above.

[0039] (Mechanism of Action and Effects) The stacked battery 10 of this embodiment described above provides the following effects.

[0040] According to this embodiment, the stacked battery 10 is a stacked battery 10 that includes a stacked body 26 in which a plurality of power generation elements 24, including a positive electrode 20 and a negative electrode 22, are stacked. The stacked battery 10 includes current collectors (30, 36) that extend from the positive electrode 20 and the negative electrode 22 and are grouped together as a plurality of divided bundles (40, 42, 44, 46) at each electrode 20, 22. The stacked battery 10 includes a pair of electrode tabs 50 to which the current collectors (30, 36) of each electrode 20, 22 are joined. The electrode tab 50 includes a base end 52 and a tip end 58 that bends from the base end 52 via a bending portion 54 and extends along the stacking direction 56, and at least one of the plurality of divided bundles (40, 42, 44, 46) is joined to the surface (70) of the tip end 58 on the stacked body 26 side.

[0041] In this configuration, the electrode tab 50 to which the current collectors (30, 36) are joined has a bent portion 54, and the tip portion 58 on the tip side of the bent portion 54 extends along the stacking direction 56 of the laminate 26. At least one of the divided bundles (40, 42, 44, 46) made up of current collectors (30, 36) extending from the power generation element 24 of the laminate 26 is joined to the joining surface 70 which is the surface of the tip portion 58 facing the laminate 26.

[0042] Thus, the electrode tab 50 having the bent portion 54 has a bonding surface 70 that is located on the side facing the laminate 26. As a result, each divided bundle 40, 42, 44, 46 of the current collectors 30, 36 that are bonded to the bonding surface 70 located on the side facing the laminate 26 are bonded to the electrode tab 50 without crossing the edge 50A of the tip of the electrode tab 50. Therefore, the laminated battery 10 can suppress damage to each current collector 30, 36 that connects the power generation element 24 and the electrode tab 50, compared to the case where each current collector 30, 36 may interfere with the edge 50A of the tip of the electrode tab 50.

[0043] Furthermore, the stacked battery 10 has a bent portion 54 formed on the electrode tab 50, and the tip portion 58 on the tip side of the bent portion 54 is extended along the stacking direction 56, making it possible to join the divided bundles (40, 42) to the tip portion 58 that extends along the stacking direction 56.

[0044] Therefore, the stacked battery 10 does not need to join all the divided bundles (40, 42, 44, 46) to the electrode tabs 50 extending in the intersecting direction 60 while spacing them out in the intersecting direction 60. Thus, the stacked battery 10 can shorten the distance 120 between the stacked body 26 having the power generation element 24 and the tip 46A of the divided bundle (46) furthest from the stacked body 26. As a result, the stacked battery 10 can be made smaller.

[0045] Here, as the capacity of the stacked battery 10 increases, the number of power generation elements 24 constituting the stacked structure 26 increases. As a result, the number of current collectors 30 and 36 joined to the electrode tab 50 increases, and there is a risk that the bonding strength of each current collector 30 and 36 to the electrode tab 50 will decrease.

[0046] Therefore, in this embodiment, the stacked battery 10 is divided into multiple bundles (40, 42, 44, 46) from which each current collector 30, 36 extending from the stacked body 26 is divided. As a result, compared to the case where many current collectors 30, 36 are joined at one location, the stacked battery 10 can increase the bonding strength of each current collector 30, 36 to the electrode tab 50, thereby improving quality.

[0047] Furthermore, in the stacked battery 10 of this embodiment, one of the multiple divided bundles (40, 42, 44, 46) is joined to the base end 52.

[0048] In this configuration, the stacked battery 10 can distribute the current input and output points to the electrode tab 50, compared to the case where all the divided bundles 40, 42, 44, and 46 are joined to the tip 58 of the electrode tab 50, thereby distributing the heat source.

[0049] Furthermore, in the stacked battery 10 of this embodiment, two or more divided bundles (40, 42) are joined to different locations on the tip portion 58, and two or more divided bundles (44, 46) are joined to different locations on the base portion 52.

[0050] In this configuration, it becomes possible to further distribute the input and output points of current to the electrode tab 50, and to further increase the bonding strength of each current collector 30, 36 to the electrode tab 50.

[0051] Next, modifications of the present invention will be described with reference to the drawings. In each modification, parts that are the same as or equivalent to those in the embodiment are denoted by the same reference numerals and their description is omitted. Furthermore, each modification provides the same effects and advantages as the embodiment with respect to parts that are the same as or equivalent to those in the embodiment.

[0052] <First Torture> Figure 5 is a side view showing the main parts of the stacked battery 200 according to the first modified example.

[0053] In this modified example, the stacked battery 200 has current collectors (30, 36) bundled for each of the poles 20, 22, which are divided into two parts: a tip bundle 212 that is joined to the tip joint 210 of the tip portion 58, and a base bundle 222 that is joined to the base joint 220 of the base portion 52.

[0054] The stacked battery 200 according to the present invention may be configured as in the first modified example.

[0055] <Second variation> Figure 6 is a side view showing the main parts of a stacked battery 240 according to a second modified example.

[0056] In this modified example, the stacked battery 240 consists of divided bundles of current collectors 30, 36 extending from one side 244 separated by a virtual straight line 242 passing through the center of the stacking direction 56 of the stacked body 26. The first divided bundle 40, which is joined to the first joining point 80, is joined with its tip 40A facing toward the virtual straight line 242.

[0057] The virtual line 242 is a virtual line that passes through the center of the stacking direction 56 of the laminated body 26 in the intersecting direction 60.

[0058] In the stacked battery 240 of this modified example, when a virtual straight line 242 is assumed to pass perpendicularly to the stacking direction 56 through the center of the stacking direction 56 of the stacked body 26, the first divided bundle 40, which is a divided bundle of current collectors 30, 36 extending from one side 244 with respect to the virtual straight line 242 and joined to the tip 58, is joined with its tip 40A facing the virtual straight line 242 side.

[0059] In this configuration, when the power generation element 24 expands in the stacking direction 56 during charging and discharging, a force F acts on the joint portion of the first divided bundle 40 and the second divided bundle 42 in a direction away from the virtual straight line 242.

[0060] Then, for example, in the second divided bundle 42, which is joined with its tip 42A facing away from the virtual straight line 242, each current collector 30, 36 extending from the joint is pulled in a direction different from the direction of extension. As a result, the angle between each current collector 30, 36 of the second divided bundle 42 and the joint portion joined to the electrode tab 50 becomes an acute angle α, and a portion of the force F along the tip portion 58 of the electrode tab 50 acts to curl the joint portions of each current collector 30, 36 from the base end side towards the tip 42A side.

[0061] In contrast, in the first divided bundle 40, which is joined with its tip 40A facing the virtual straight line 242, each current collector 30, 36 extending from the joint is pulled in the same direction as the extension direction. As a result, the angle between each current collector 30, 36 of the first divided bundle 40 and the joint portion joined to the electrode tab 50 becomes an obtuse angle β, and a portion of the force F along the tip of the electrode tab 50 acts in a direction away from the tip 40A side at the base end side of the joint portion of each current collector 30, 36.

[0062] Therefore, when the tip 40A of the first divided bundle 40 is joined with the virtual straight line 242 facing the current collector 30, 36, the peeling force acting in the direction of peeling from the electrode tab 50 is smaller compared to when the tip is joined with the opposite direction to the virtual straight line 242. This makes it possible to enhance the peeling suppression effect of each current collector 30, 36 when the power generation element 24 expands in the stacking direction 56.

[0063] Therefore, in this modified example, it is possible to enhance the peeling suppression effect of the first split bundle 40.

[0064] <Third variation> Figure 7 is a side view showing the main parts of a stacked battery 260 according to a third modified example.

[0065] In this modified example, the stacked battery 260 consists of divided bundles of current collectors 30 and 36 extending from one side 244 with respect to the virtual straight line 242. The first divided bundle 40 and the second divided bundle 42, which are divided bundles joined to the first joint point 80 and the second joint point 82, have their tips 40A and 42A facing toward the virtual straight line 242.

[0066] In this modified example, it is possible to enhance the peeling suppression effect of the first split bundle 40 and the second split bundle 42.

[0067] <Fourth variation> Figure 8 is a side view showing the main parts of a stacked battery 280 according to the fourth modified example.

[0068] In this modified example, the stacked battery 280 has a first connection point 80 on the tip 58 of the electrode tab 50 to which the first divided bundle 40 is joined, and a second connection point 82 on which the second divided bundle 42 is joined. In addition, the tip 58 of the electrode tab 50 has a third connection point 84 on which the third divided bundle 44 is joined, and a fourth connection point 86 on which the fourth divided bundle 46 is joined. Each divided bundle 40, 42, 44, and 46 is joined to the electrode tab 50 with its tip 40A, 42A, 44A, and 46A facing towards the virtual straight line 242.

[0069] This modified example will produce the same effects and advantages as the embodiment and each modified example with respect to parts that are the same as or equivalent to the embodiment and each modified example.

[0070] <Fifth variation> Figure 9 is a side view showing the main parts of the stacked battery 300 according to the fifth modified example.

[0071] In this modified example, the electrode tab 50 of the stacked battery 300 has its tip portion 58 folded back so that it overlaps the base portion 52, and the tip portion 58 and the base portion 52 are stacked without any gaps.

[0072] In this modified example of the stacked battery 300, the electrode tab 50 is folded back so that its tip portion 58 overlaps its base portion 52.

[0073] In this configuration, the stacked battery 300 can be miniaturized because the dimensions in the stacking direction 56 are reduced in the area where the electrode tabs 50 are located.

[0074] Furthermore, this modified example will produce the same effects and advantages as the embodiment and each modified example with respect to parts that are the same as or equivalent to the embodiment and each modified example.

[0075] Although embodiments of the present invention have been described above, these embodiments only represent a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

[0076] The stacked batteries 10, 200, 240, 260, 280, and 300 mentioned above were explained using their application in electric vehicles as an example, but the uses of stacked batteries 10, 200, 240, 260, 280, and 300 are not limited to this. Stacked batteries 10, 200, 240, 260, 280, and 300 may also be used for other purposes. [Explanation of symbols]

[0077] 10: Stacked battery, 20: Positive electrode, 22: Negative electrode, 24: Power generation element, 26: Stacked body, 30: Positive electrode current collector, 36: Negative electrode current collector, 40: First split bundle, 40A: Tip, 42: Second split bundle, 42A: Tip, 44: Third split bundle, 46: Fourth split bundle, 46A: Tip, 50: Electrode tab, 50A: Edge, 52: Base end, 54: Bending portion, 56: Stacking direction, 58: Tip portion, 80: First junction, 82: Second junction, 84: Third junction, 86: Fourth junction, 200: Stacked battery, 210: Tip junction, 212: Tip split bundle, 220: Base junction, 222: Base split bundle, 240: Stacked battery, 242: Virtual line, 260: Stacked battery, 280: Stacked battery, 300: Stacked battery

Claims

1. A stacked battery including a stack in which multiple power generation elements, including a positive electrode and a negative electrode, are stacked, A current collector extending from the positive electrode and the negative electrode, and bundled together as multiple divided bundles at each electrode, Each pole comprises a pair of electrode tabs to which the current collector is joined, The electrode tab comprises a base portion and a tip portion that bends from the base portion via a bending portion and extends along the stacking direction, At least one of the multiple divided bundles is joined to the laminate-side surface of the tip portion. Stacked battery.

2. A stacked battery according to claim 1, The electrode tab is folded back so that its tip overlaps the base end. Stacked battery.

3. A stacked battery according to claim 1 or claim 2, One of the multiple divided bundles is joined to the base end, Stacked battery.

4. A stacked battery according to claim 3, At the aforementioned tip, two or more of the aforementioned divided bundles are joined at different locations. Two or more of the divided bundles are joined to the base end at different locations. Stacked battery.

5. A stacked battery according to claim 1, When a virtual straight line is assumed to pass perpendicular to the stacking direction through the center of the stacking direction of the laminate, the divided bundle of the current collector extending from one side of the virtual straight line, and joined to the tip of the divided bundle, is joined with its tip facing the side of the virtual straight line. Stacked battery.

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