Battery

Abstract

To obtain a battery with improved heat dissipation performance. [Solution] The battery 10 includes an electrode body 14, a case 12, a first current collector terminal 20 provided inside the case 12 and connected to a positive electrode current collector, a second current collector terminal 22 connected to a negative electrode current collector, a first insulating member 24 that insulates the case 12 from the first current collector terminal 20, a second insulating member 26 that insulates the case 12 from the second current collector terminal 22, a plurality of first external terminals 28 arranged along a first direction, and a plurality of second external terminals 30 arranged along a second direction. The positive electrode current collector is connected to the first external terminal 28 with respect to the first current collector terminal 20 on one side and the other side in the first direction, and the negative electrode current collector is connected to the second external terminal 30 with respect to the second current collector terminal 22 on one side and the other side in the second direction.

Description

Technical Field

[0001] The present invention relates to a battery.

Background Art

[0002] Patent Document 1 discloses a battery in which an electrode body is housed in a case. Further, in the battery disclosed in Patent Document 1, a positive electrode current collecting terminal and a negative electrode current collecting terminal are provided in the case. The positive electrode current collecting terminal is connected to the positive electrode of the electrode body via a plurality of positive electrode current collecting tabs, and the negative electrode current collecting terminal is connected to the negative electrode of the electrode body via a plurality of negative electrode current collecting tabs.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a structure in which one external terminal is provided on each of the positive electrode side and the negative electrode side, like the battery disclosed in Patent Document 1 above, it is difficult to sufficiently dissipate the heat generated in the electrode body to the outside of the battery, and there is room for improvement from the viewpoint of improving heat dissipation performance.

[0005] In consideration of the above facts, an object of the present invention is to obtain a battery with improved heat dissipation performance.

Means for Solving the Problems

[0006] The battery according to claim 1 comprises an electrode body having a positive electrode current collector and a negative electrode current collector; a case for housing the electrode body, comprising a peripheral wall, a positive electrode side cover portion located at an opening on one side of the peripheral wall, and a negative electrode side cover portion located at an opening on the other side of the peripheral wall; a first current collector terminal provided inside the case and joined to the positive electrode current collector; a second current collector terminal provided inside the case and joined to the negative electrode current collector; a first insulating member provided between the case and the first current collector terminal to insulate them from each other; a second insulating member provided between the case and the second current collector terminal to insulate them from each other; and a first direction The device has multiple first external terminals arranged along a direction, each positioned in an insertion hole formed in the positive electrode side cover and electrically connected to the first current collector terminal, and multiple second external terminals arranged along a second direction, each positioned in an insertion hole formed in the negative electrode side cover and electrically connected to the second current collector terminal, wherein the positive electrode current collector is joined to the first current collector terminal on one side and the other side in the first direction with respect to the first external terminal, and the negative electrode current collector is joined to the second current collector terminal on one side and the other side in the second direction with respect to the second external terminal.

[0007] In the battery according to claim 1, an electrode body is housed in a case having a peripheral wall, a positive electrode side cover, and a negative electrode side cover, and the electrode body comprises a positive electrode current collector and a negative electrode current collector. Furthermore, a first current collector terminal and a second current collector terminal are provided inside the case, the first current collector terminal is connected to the positive electrode current collector, and the second current collector terminal is connected to the electrode current collector. In addition, a first insulating member is provided between the case and the first current collector terminal to insulate them, and a second insulating member is provided between the case and the second current collector terminal to insulate them. Furthermore, a plurality of first external terminals are arranged in through holes formed in the positive electrode side cover and are electrically connected to the first current collector terminal. In addition, a plurality of second external terminals are arranged in through holes formed in the negative electrode side cover and are electrically connected to the second current collector terminal. In this way, by providing multiple first external terminals and second external terminals, the number of heat dissipation paths increases compared to a configuration with one first external terminal and one second external terminal, allowing for greater heat dissipation from the electrode body.

[0008] Furthermore, the positive electrode current collector is joined to the first external terminal on one side and the other side in the first direction. This allows the heat generated in the electrode to be dispersed and transferred to both sides of the first external terminal. Similarly, the negative electrode current collector is joined to the second external terminal on one side and the other side in the second direction, so that the heat generated in the electrode is dispersed and transferred to both sides of the second external terminal. This suppresses localized heating of the first and second current collectors. [Effects of the Invention]

[0009] As explained above, the battery according to the present invention can improve heat dissipation performance. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic cross-sectional view of a battery cell according to an embodiment. [Figure 2] This is a cross-sectional view showing the state after cutting along line 2-2 in Figure 1. [Figure 3] This is an enlarged cross-sectional view of the main part, showing an enlarged view of the main part of Figure 1. [Figure 4] This is a cross-sectional view showing the state after cutting along line 4-4 in Figure 3. [Figure 5] This is a cross-sectional view illustrating the process of joining the positive electrode current collector to the first current collector terminal. [Figure 6] This is a cross-sectional view showing the positive electrode current collector connected to the first current collector terminal. [Figure 7] This is a schematic cross-sectional view of a battery cell relating to the first modified example. [Figure 8] This is a schematic cross-sectional view of a battery cell related to a reference example. [Figure 9] This is a schematic cross-sectional view of a battery cell related to a reference example. [Modes for carrying out the invention]

[0011] Figure 1 is a schematic cross-sectional view of a battery cell 10 as a battery according to this embodiment. For example, the battery cell 10 of this embodiment constitutes a battery pack mounted under the floor of an electric vehicle and is configured to store power for supplying to a drive motor (not shown).

[0012] Furthermore, the battery cell 10 of this embodiment can be widely applied to vehicles that utilize power supplied from a secondary battery as at least part of the drive source, such as hybrid vehicles (HV) and plug-in hybrid vehicles (PHEV), in addition to BEVs (Battery Electric Vehicles).

[0013] The battery cell 10 according to this embodiment is composed of a case 12 and an electrode body 14. The case 12 constitutes the outer shell of the battery cell 10 and is formed in a substantially rectangular parallelepiped shape. As an example, the case 12 of this embodiment is composed of a substantially cylindrical peripheral wall portion 12A, a positive electrode side cover portion 12B that closes the opening on one side of the peripheral wall portion 12A, and a negative electrode side cover portion 12C that closes the opening on the other side of the peripheral wall portion 12A.

[0014] The peripheral wall portion 12A is formed from a roughly rectangular tubular metal with open ends, and is sized to accommodate the electrode body 14 inside. The positive electrode side cover portion 12B is a metal member that is fitted, welded, or otherwise fixed to the opening on one side of the peripheral wall portion 12A, and closes the opening on one side of the peripheral wall portion 12A. The negative electrode side cover portion 12C is a metal member that is fitted, welded, or otherwise fixed to the opening on the other side of the peripheral wall portion 12A, and closes the opening on the other side of the peripheral wall portion 12A.

[0015] FIG. 2 is a cross-sectional view showing a state cut along the line 2-2 of FIG. 1. As shown in FIG. 2, the electrode body 14 is composed of a positive current collector 40 and a negative current collector 48. Specifically, the electrode body 14 is formed by laminating a positive current collector 40, a positive electrode mixture 42, a solid electrolyte 44, a negative electrode mixture 46, and a negative current collector 48 in this order. In FIG. 2, for convenience of explanation, a state in which two layers of the positive current collector 40 are laminated and one layer of the negative current collector 48 is laminated is illustrated, but in reality, a larger number of sheets of the positive current collector 40 and the negative current collector 48 are laminated.

[0016] The negative current collector 48 is disposed at the center in the stacking direction and is formed of a metal foil. For example, a copper foil is preferable as the negative current collector 48.

[0017] The negative electrode mixture 46 is applied to both surfaces of the negative current collector 48. The negative electrode mixture 46 is a mixture of a negative electrode active material, a conductive auxiliary material, a binder, etc. Examples of the negative electrode active material include at least one selected from the group consisting of natural graphite, artificial graphite, hard carbon (carbon with low graphitization property) or soft carbon (carbon with high graphitization property), Si, SiOx (0 < x < 2), Si-based alloy, Sn, SnOx (0 < x < 2), Li, Li-based alloy, and Li4Ti5O12. Examples of artificial graphite include highly oriented graphite, mesocarbon microbeads, etc. As the negative electrode active material, artificial graphite is preferable.

[0018] On the side of the negative electrode composite material 46 opposite to the negative electrode current collector 48, a solid electrolyte 44 is laminated. Further, on the side of the solid electrolyte 44 opposite to the negative electrode composite material 46, a positive electrode composite material 42 is laminated. The positive electrode composite material 42 is a mixture of a positive electrode active material, a conductive auxiliary material, a binder, etc., and is coated on the positive electrode current collector 40. The positive electrode active material is not particularly limited, and conventionally known materials can be appropriately used. For example, as the positive electrode active material, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, Li(NiCoMn)O2, Li(NiCoAl)O2, and LiFePO4 can be mentioned. Note that the positive electrode active material particles may be Hi-Nickel (a positive electrode active material with a high Ni ratio) or a Li-Ni-Co-Mn-based composite oxide or a ternary positive electrode active material.

[0019] The positive electrode current collector 40 is formed of a metal foil, and as the positive electrode current collector 40, an aluminum foil is preferable. Thus, as an example, in the electrode body 14 of the present embodiment, the negative electrode current collector 48 is disposed at the center in the stacking direction, and the positive electrode current collectors 40 are disposed on both sides of the negative electrode current collector 48. Therefore, the number of positive electrode current collectors 40 is larger than that of the negative electrode current collector 48.

[0020] As shown in FIG. 1, the electrode body 14 has a longitudinal direction and a short-side direction when viewed from the stacking direction. The positive electrode tab 16 extends from one end portion in the longitudinal direction of the electrode body 14, and the negative electrode tab 18 extends from the other end portion in the longitudinal direction. In the following description, the short-side direction of the electrode body 14 may be referred to as the width direction.

[0021] The positive electrode tab 16 is formed by collecting positive electrode foils extending from a plurality of positive electrode current collectors 40 constituting the electrode body 14. In the present embodiment, as an example, it is divided into three, i.e., a first positive electrode tab 16A, a second positive electrode tab 16B, and a third positive electrode tab 16C.

[0022] The first positive electrode tab 16A extends from one end of the electrode body 14 in the width direction (upper right side of the page) toward the positive electrode side cover 12B and is joined to the first current collector terminal 20, which will be described later. The second positive electrode tab 16B extends from the center of the electrode body 14 in the width direction toward the positive electrode side cover 12B and is joined to the first current collector terminal 20, which will be described later. Furthermore, the third positive electrode tab 16C extends from the other end of the electrode body 14 in the width direction (lower right side of the page) toward the positive electrode side cover 12B and is joined to the first current collector terminal 20, which will be described later.

[0023] On the other hand, the negative electrode tab 18 is formed by collecting negative electrode foils extending from a plurality of negative electrode current collectors 48 that constitute the electrode body 14, and in this embodiment, as an example, it is divided into three parts: a first negative electrode tab 18A, a second negative electrode tab 18B, and a third negative electrode tab 18C.

[0024] The first negative electrode tab 18A extends from the corner of one end of the electrode body 14 in the width direction (upper left side of the paper) toward the negative electrode side cover 12C and is joined to the second current collection terminal 22, which will be described later. The second negative electrode tab 18B extends from the center of the electrode body 14 in the width direction toward the negative electrode side cover 12C and is joined to the second current collection terminal 22, which will be described later. Furthermore, the third negative electrode tab 18C extends from the corner of the other end of the electrode body 14 in the width direction (lower left side of the paper) toward the negative electrode side cover 12C and is joined to the second current collection terminal 22, which will be described later.

[0025] The first current collector terminal 20 is a long metal member located inside the case 12 and extending along the width direction of the electrode body 14. Specifically, the first current collector terminal 20 is attached to the positive electrode side cover portion 12B of the case 12 with a first insulating member 24 in between, and extends from one end to the other end of the positive electrode side cover portion 12B. The first insulating member 24 is made of an insulating material, and this first insulating member 24 insulates the case 12 from the first current collector terminal 20.

[0026] The second current collector terminal 22 is a long metal member located inside the case 12 and extending along the width direction of the electrode body 14. Specifically, the second current collector terminal 22 is attached to the negative electrode side cover portion 12C of the case 12 with a second insulating member 26 in between, and extends from one end to the other end of the negative electrode side cover portion 12C. The second insulating member 26 is made of an insulating material, and this second insulating member 26 insulates the case 12 from the second current collector terminal 22.

[0027] In this case, the positive electrode side cover portion 12B of the case 12 is provided with a plurality of first external terminals 28, and the negative electrode side cover portion 12C is provided with a plurality of second external terminals 30. In this embodiment, as an example, two first external terminals 28 and two second external terminals 30 are provided.

[0028] The first external terminal 28 is located at a position that divides the positive electrode side cover portion 12B into approximately three equal parts, and the second external terminal 30 is located at a position that divides the negative electrode side cover portion 12C into approximately three equal parts. For this reason, in this embodiment, as an example, the first external terminal 28 and the second external terminal 30 are located at positions that face each other. The details of the first external terminal 28 will be described below, but the second external terminal 30 has a similar configuration.

[0029] Figure 3 is an enlarged cross-sectional view of the main part of Figure 1, showing an enlarged view of the main part. As shown in Figure 3, the first external terminal 28 is composed of a shaft portion 28A, an external flange portion 28B, and an internal flange portion 28C. The shaft portion 28A extends along the longitudinal direction of the electrode body 14 and is inserted through the positive electrode side cover portion 12B of the case 12.

[0030] The outer flange portion 28B is formed to have a larger diameter than the shaft portion 28A and is located outside the positive electrode side cover portion 12B. The inner flange portion 28C is also formed to have a larger diameter than the shaft portion 28A and is located inside the case 12. As a result, one end of the first external terminal 28 is exposed to the outside of the case 12.

[0031] A resin component 32 is interposed between the first external terminal 28 and the positive electrode side cover portion 12B. The resin component 32 is provided on the hole wall and edge of the insertion hole formed in the positive electrode side cover portion 12B, and further covers the circumferential surface of the external flange portion 28B of the first external terminal 28. Thus, the resin component 32 insulates the first external terminal 28 from the positive electrode side cover portion 12B.

[0032] The internal flange portion 28C of the first external terminal 28 bites into the first current collector terminal 20, and the first external terminal 28 sandwiches the first current collector terminal 20, the first insulating member 24, and the positive electrode side cover portion 12B. In other words, the first external terminal 28 is fixed with the first insulating member 24 sandwiched between the case 12 and the first current collector terminal 20. The first external terminal 28 in this embodiment is made of a crimping member and is formed by inserting it through the positive electrode side cover portion 12B and then crushing and crimping the external flange portion 28B and the internal flange portion 28C.

[0033] Furthermore, since the first external terminal 28 is electrically connected to the first current collection terminal 20, the first positive electrode tab 16A, the second positive electrode tab 16B, and the third positive electrode tab 16C of the electrode body 14 are electrically connected to the first external terminal 28 via the first current collection terminal 20.

[0034] As shown in Figure 1, the second external terminal 30, like the first external terminal 28, is constructed using a crimping member and is formed by crimping it while it is inserted through the negative electrode side cover portion 12C. That is, the second external terminal 30 is fixed with the second insulating member 26 sandwiched between the case 12 and the second current collection terminal 22. The second external terminal 30 is insulated from the negative electrode side cover portion 12C and is electrically connected to the second current collection terminal 22. Therefore, the first negative electrode tab 18A, the second negative electrode tab 18B, and the third negative electrode tab 18C of the electrode body 14 are electrically connected to the second external terminal 30 via the second current collection terminal 22.

[0035] Furthermore, in this embodiment, the electrode body 14 is joined to the first current collection terminal 20 on both sides of the first external terminal 28 when viewed from the stacking direction, and is joined to the second current collection terminal 22 on both sides of the second external terminal 30. Specifically, the first positive electrode tab 16A and the second positive electrode tab 16B are arranged on either side of one of the first external terminals 28, and the second positive electrode tab 16B and the third positive electrode tab 16C are arranged on either side of the other first external terminal 28.

[0036] Furthermore, the first negative electrode tab 18A and the second negative electrode tab 18B are arranged on either side of one second external terminal 30, and the second negative electrode tab 18B and the third negative electrode tab 18C are arranged on either side of the other second external terminal 30.

[0037] In this embodiment, the length of the region where the first positive electrode tab 16A, the second positive electrode tab 16B, and the third positive electrode tab 16C are joined to the first current collector terminal 20 is more than half the length of the first current collector terminal 20 when viewed from the stacking direction of the electrode body 14. Specifically, the positive electrode tabs 16 and the first current collector terminal 20 are joined in most of the region except for the portion where the first external terminal 28 is provided.

[0038] Furthermore, the length of the region where the first negative electrode tab 18A, the second negative electrode tab 18B, and the third negative electrode tab 18C are joined to the second current collector terminal 22 is more than half the length of the second current collector terminal 22 when viewed from the stacking direction of the electrode body 14. Specifically, the negative electrode tab 18 and the second current collector terminal 22 are joined in most of the region except for the portion where the second external terminal 30 is provided.

[0039] Figure 4 is a cross-sectional view showing the state after cutting along line 4-4 in Figure 3. As shown in Figure 4, the positive electrode tab 16 is joined to the first current collection terminal 20 in a state where the positive electrode foil has been collected and folded. The process of joining the positive electrode tab 16 to the first current collection terminal 20 will be described below with reference to Figures 5 and 6.

[0040] Figure 5 is a cross-sectional view illustrating the process of joining the positive electrode tab 16 of the positive electrode current collector to the first current collector terminal 20, and Figure 6 is a cross-sectional view showing the state in which the positive electrode tab 16 has been joined to the first current collector terminal 20. As shown in Figure 5, with the positive electrode tab 16 bent and overlapped with the first current collector terminal 20, an anvil 100, which will serve as a receiving jig, is placed on one side of the first current collector terminal 20.

[0041] Furthermore, an ultrasonic horn 102 is placed on the other side of the first current collection terminal 20, and ultrasonic waves are generated while the ultrasonic horn 102 is pressed against the positive electrode tab 16, thereby vibrating the ultrasonic horn 102 and joining the positive electrode tab 16 to the first current collection terminal 20. At this time, the surface of the anvil 100 is formed in an uneven shape, and protrusions are formed on the ultrasonic horn 102. Then, ultrasonic bonding is performed by pressing the protrusions of the ultrasonic horn 102 against the positive electrode tab 16.

[0042] As shown in Figure 6, when the positive electrode tab 16 is connected to the first current collector terminal 20, the surface of the first current collector terminal 20 on the anvil 100 side becomes uneven. Also, grooves are formed on the positive electrode tab 16 in the area where the ultrasonic horn 102 is pressed. Note that in Figure 6, the unevenness and grooves are exaggerated for illustrative purposes.

[0043] As shown in Figure 1, the first insulating member 24 is sandwiched between the first current collector terminal 20 and the positive electrode side cover portion 12B, so that the uneven surface of the first current collector terminal 20 and the first insulating member 24 are in contact. The second current collector terminal 22 is ultrasonically bonded in the same way as the first current collector terminal 20, so the surface of the second current collector terminal 22 on the side of the second insulating member 26 is formed in an uneven shape. (action) Next, the operation of the battery cell 10 according to this embodiment will be explained.

[0044] In the battery cell 10 according to this embodiment, an electrode body 14 is housed in a case 12, and the electrode body 14 includes a positive electrode current collector 40 and a negative electrode current collector 48 (see Figure 2). Inside the case 12, a first current collector terminal 20 and a second current collector terminal 22 are provided, with the first current collector terminal 20 connected to the positive electrode current collector 40 and the second current collector terminal 22 connected to the negative electrode current collector 48.

[0045] Furthermore, a first insulating member 24 is provided between the positive electrode side cover 12B (case 12) and the first current collection terminal 20 to insulate them, and a second insulating member 26 is provided between the negative electrode side cover 12C (case 12) and the second current collection terminal 22 to insulate them. In addition, a first external terminal 28 is inserted through the positive electrode side cover 12B, with one end of this first external terminal 28 exposed to the outside of case 12 and the other end electrically connected to the first current collection terminal 20. Also, a second external terminal 30 is inserted through the negative electrode side cover 12C, with one end of this second external terminal 30 exposed to the outside of case 12 and the other end electrically connected to the second current collection terminal 22. As a result, power can be output from the battery cell 10 to the outside.

[0046] Furthermore, at least one of the first external terminal 28 and the second external terminal 30 is provided in multiples. This increases the heat dissipation paths compared to a configuration where only one of the first external terminal 28 and the second external terminal 30 are provided, allowing more heat generated in the electrode body 14 to be dissipated. In particular, in this embodiment, since both the first external terminal 28 and the second external terminal 30 are provided in multiples, heat can be dissipated in a balanced manner from both the first external terminal 28 and the second external terminal 30.

[0047] Furthermore, in the battery cell 10 of this embodiment, the positive electrode tabs 16 are joined to the first current collector terminal 20 on both sides of the first external terminal 28 when viewed from the stacking direction of the electrode body 14, so that the heat generated in the electrode body 14 is dispersed and transferred to both sides of the first external terminal 28. Similarly, the negative electrode tabs 18 are joined to the second current collector terminal 22 on both sides of the second external terminal 30 when viewed from the stacking direction of the electrode body 14, so that the heat generated in the electrode body 14 is dispersed and transferred to both sides of the second external terminal 30. This makes it possible to suppress localized heating of the first current collector terminal 20 and the second current collector terminal 22.

[0048] Furthermore, in the battery cell 10 of this embodiment, the positive electrode tab 16 is joined to the first current collection terminal 20 with a length of more than half its length, and the negative electrode tab 18 is joined to the second current collection terminal 22 with a length of more than half its length. As a result, heat dissipation performance is improved compared to configurations in which the positive electrode tab 16 is joined to the first current collection terminal 20 with a length of less than half its length, or configurations in which the negative electrode tab 18 is joined to the second current collection terminal 22 with a length of less than half its length.

[0049] Furthermore, in the battery cell 10 of this embodiment, the first external terminal 28 is provided on one end of the electrode body 14 in the longitudinal direction, and the second external terminal 30 is provided on the other end of the electrode body 14 in the longitudinal direction, so that heat can be dissipated from both sides of the electrode body 14 in the longitudinal direction. In addition, the distance between the first external terminal 28 and the second external terminal 30 is increased, so that the heat can be dispersed.

[0050] Furthermore, as shown in Figure 3, the first external terminal 28 is fixed with the first insulating member 24 sandwiched between the case 12 and the first current collector terminal 20. This allows for a simple structure to prevent electrical conductivity between the case 12 and the first current collector terminal 20. Similarly, the second external terminal 30 is fixed with the second insulating member 26 sandwiched between the case 12 and the second current collector terminal 22, thus allowing for a simple structure to prevent electrical conductivity between the case 12 and the second current collector terminal 22.

[0051] Furthermore, in this embodiment, as shown in Figure 6, the surface of the first current collector terminal 20 facing the first insulating member 24 is formed in an uneven shape. Therefore, as shown in Figure 1, when the first current collector terminal 20 is assembled, it is possible to suppress the first current collector terminal 20 from sliding against the first insulating member 24 and releasing the insulation state. Similarly, since the surface of the second current collector terminal 22 facing the second insulating member 26 is formed in an uneven shape, it is possible to suppress the second current collector terminal 22 from sliding against the second insulating member 26 and releasing the insulation state.

[0052] In the above embodiment, as shown in Figure 1, the first external terminal 28 is provided at positions that divide the positive electrode side cover portion 12B into approximately three equal parts, and the second external terminal 30 is provided at positions that divide the negative electrode side cover portion 12C into approximately three equal parts. However, the embodiment is not limited to this configuration. For example, as shown in the first modified example in Figure 7, the number and position of the first external terminals 28 and the number and position of the second external terminals 30 may be changed.

[0053] (First variation) Figure 7 is a schematic cross-sectional view of a battery cell 50 according to the first modified example. As shown in Figure 7, the battery cell 50 of this modified example is equipped with three first external terminals 28 and two second external terminals 30.

[0054] The three first external terminals 28 are positioned opposite the center of the electrode body 14 in the width direction when viewed from the stacking direction of the electrode body 14. Specifically, the first external terminals 28 are provided coaxially with the center line passing through the center of the electrode body 14 in the width direction. In addition, first external terminals 28 are provided on both sides of this central first external terminal 28 with a small gap between them.

[0055] In this modified example, since the three first external terminals 28 are arranged with a small gap between them, a positive electrode tab is not provided in the center of the electrode body 14 in the width direction. Specifically, the first positive electrode tab 16A extends from the corner of one end of the electrode body 14 in the width direction (upper right side of the page) toward the positive electrode side cover portion 12B and is joined to the first current collection terminal 20. The third positive electrode tab 16C extends from the corner of the other end of the electrode body 14 in the width direction (lower right side of the page) toward the positive electrode side cover portion 12B and is joined to the first current collection terminal 20.

[0056] Therefore, the three first external terminals 28 are positioned between the first positive tab 16A and the third positive tab 16C.

[0057] On the other hand, the two second external terminals 30 are positioned opposite the center of the electrode body 14 in the width direction when viewed from the stacking direction of the electrode body 14. Specifically, the second external terminals 30 are provided on both sides of the center line passing through the center of the electrode body 14 in the width direction, and the two second external terminals 30 are arranged with a small gap between them.

[0058] In this modified example, since the two second external terminals 30 are positioned with a small gap between them, a negative electrode tab is not provided in the center of the electrode body 14 in the width direction. Specifically, the first negative electrode tab 18A extends from the corner of one end of the electrode body 14 in the width direction (upper left side of the page) toward the negative electrode side cover portion 12C and is joined to the second current collection terminal 22. The third negative electrode tab 18C extends from the corner of the other end of the electrode body 14 in the width direction (lower left side of the page) toward the negative electrode side cover portion 12C and is joined to the second current collection terminal 22.

[0059] In this modified battery cell 50, there is no positive electrode tab between adjacent first external terminals 28, and no negative electrode tab between adjacent second external terminals 30. Therefore, compared to a configuration in which a positive electrode tab is provided between adjacent first external terminals 28, or a negative electrode tab is provided between adjacent second external terminals 30, the gap between adjacent first external terminals 28 and the gap between adjacent second external terminals 30 can be reduced. This allows for space saving.

[0060] Furthermore, in the modified battery cell 50, the number of first external terminals 28 is greater than the number of second external terminals 30. Therefore, even in configurations where the positive electrode tab 16 generates a large amount of heat, such as when the number of foils attached to the positive electrode tab 16 is greater than the number of foils attached to the negative electrode tab 18, the rise in temperature on the positive electrode side can be suppressed.

[0061] (Reference example) Figure 8 is a schematic cross-sectional view of a battery cell 60 according to a reference example. As shown in Figure 8, the battery cell 60 of this reference example has two first external terminals 28 and two second external terminals 30, similar to the embodiment, but the positions of the first external terminals 28 and the second external terminals 30 are different.

[0062] The two first external terminals 28 are inserted through the positive electrode side cover portion 12B. One of the first external terminals 28 is positioned on the positive electrode side cover portion 12B opposite one end of the electrode body 14 in the width direction. The other first external terminal 28 is positioned on the positive electrode side cover portion 12B opposite the other end of the electrode body 14 in the width direction.

[0063] The positive electrode tab 16 is positioned between the two first external terminals 28 and is wider than the first positive electrode tab 16A, second positive electrode tab 16B, and third positive electrode tab 16C of the embodiment. In this reference example, only one positive electrode tab 16 is provided.

[0064] The two second external terminals 30 are inserted through the negative electrode side cover portion 12C. One of the second external terminals 30 is positioned on the negative electrode side cover portion 12C opposite one end of the electrode body 14 in the width direction. The other second external terminal 30 is positioned on the negative electrode side cover portion 12C opposite the other end of the electrode body 14 in the width direction.

[0065] The negative electrode tab 18 is positioned between the two second external terminals 30 and is wider than the first negative electrode tab 18A, second negative electrode tab 18B, and third negative electrode tab 18C of the embodiment. In this reference example, only one negative electrode tab 18 is provided.

[0066] In the battery cell 60 of this reference example, the positive electrode tab 16 is joined to the first current collection terminal 20 over a wide area in the widthwise central part of the electrode body 14, where the temperature tends to rise, and the negative electrode tab 18 is joined to the second current collection terminal 22 over a wide area. This allows for effective heat dissipation.

[0067] (Reference example) Figure 9 is a schematic cross-sectional view of a battery cell 70 according to a reference example. As shown in Figure 9, the battery cell 70 of this reference example has three first external terminals 28 and two second external terminals 30, similar to the first modified example, but the positions of the first external terminals 28 and the second external terminals 30 are different.

[0068] The three first external terminals 28 are inserted through the positive electrode side cover portion 12B and are provided adjacent to one end of the electrode body 14 in the width direction on the positive electrode side cover portion 12B. Therefore, no first external terminals 28 are provided at the position opposite to the other end of the electrode body 14 in the width direction.

[0069] The positive electrode tab 16 extends from the other end in the width direction of the electrode body 14 toward the positive electrode side cover portion 12B and is joined to the first current collection terminal 20. Furthermore, the positive electrode tab 16 is formed to be wider than the first positive electrode tab 16A, second positive electrode tab 16B, and third positive electrode tab 16C of the embodiment, and only one positive electrode tab 16 is provided.

[0070] The two second external terminals 30 are inserted through the negative electrode side cover portion 12C and are provided adjacent to the other end of the electrode body 14 in the width direction on the negative electrode side cover portion 12C. Therefore, no second external terminals 30 are provided at the position opposite to one end of the electrode body 14 in the width direction.

[0071] The negative electrode tab 18 extends from one end of the electrode body 14 in the width direction toward the negative electrode side cover portion 12C and is joined to the second current collection terminal 22. Furthermore, the negative electrode tab 18 is formed to be wider than the first negative electrode tab 18A, second negative electrode tab 18B, and third negative electrode tab 18C of the embodiment, and only one negative electrode tab 18 is provided.

[0072] In the battery cell 70 of this reference example, the first external terminal 28 and the second external terminal 30 are arranged diagonally when viewed from the stacking direction of the electrode body 14. This ensures a long heat dissipation path and prevents heat from accumulating inside the case 12.

[0073] Although the embodiments and modified versions of battery cells 10, 50, 60, and 70 have been described above, the invention is not limited thereto and can be implemented in various forms without departing from the spirit of the present invention. For example, in the above embodiments and modified versions, the first current collector terminal 20 and positive electrode tab 16 are provided on one longitudinal end of the electrode body 14, and the second current collector terminal 22 and negative electrode tab 18 are provided on the other longitudinal end, but the invention is not limited thereto, and the first current collector terminal and the second current collector terminal may be provided on one longitudinal end of the electrode body 14. Alternatively, the first current collector terminal and the second current collector terminal may be provided on one short end of the electrode body 14.

[0074] Furthermore, in the above embodiments and modifications, the first external terminal 28 and the second external terminal 30 were fixed by crimping, but the invention is not limited to this, and they may be fixed by other methods. [Explanation of symbols]

[0075] 10, 50, 60, 70 battery cells (batteries) 12 cases 14 Electrode body 20 1st current collector terminal 22 2nd current collector terminal 24 First insulating member 26 Second insulating member 28 First external terminal 30 Second external terminal 40 Positive electrode current collector 48 Negative electrode current collector

Claims

[Claim 1] An electrode body comprising a positive electrode current collector and a negative electrode current collector, A case for housing the electrode body, comprising a peripheral wall, a positive electrode side cover portion located at an opening on one side of the peripheral wall, and a negative electrode side cover portion located at an opening on the other side of the peripheral wall, A first current collector terminal is provided inside the case and connected to the positive electrode current collector, A second current collector terminal is provided inside the case and connected to the negative electrode current collector, A first insulating member is provided between the case and the first current collector terminal to insulate the two, A second insulating member is provided between the case and the second current collector terminal to insulate them from each other. Multiple first external terminals are arranged along the first direction, each positioned within an insertion hole formed in the positive electrode side cover and electrically connected to the first current collection terminal, Multiple second external terminals are arranged along the second direction, each positioned within an insertion hole formed in the negative electrode side cover and electrically connected to the second current collection terminal, It has, The positive electrode current collector is connected to the first external terminal on one side and the other side in the first direction, A battery in which the negative electrode current collector is connected to the second external terminal on one side and the other side in the second direction.

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