Battery

Abstract

To obtain a battery that can effectively reduce heat generation at external terminals. [Solution] The battery 10 includes an electrode body 14 equipped with a current collector, a case 12 housing the electrode body 14, a current collector terminal 20 provided inside the case 12, and a plurality of external terminals 28 electrically connected to the current collector terminal 20. Two external terminals 28 are arranged along one direction of the case 12, and the current collector and the current collector terminal 14 are joined between the two external terminals 28 and outward in one direction from each external terminal 28. The length along one direction of the region where the current collector and the current collector terminal 20 are joined between the two external terminals 28 is longer along one direction of the region where the current collector and the current collector terminal 20 are joined outward in one direction from each external terminal 28.

Description

Technical Field

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[0001] The present invention relates to a battery.

Background Art

[0002] Patent Document 1 discloses a structure in which a plurality of current collecting tabs are branched and connected to a current collecting terminal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in order to suppress heat generation during energization, a structure having a plurality of external terminals for each electrode is known. However, unless the distance between the external terminals is optimized, the current density cannot be reduced, and there is room for improvement from the viewpoint of effectively suppressing heat generation of the external terminals.

[0005] In consideration of the above facts, an object of the present invention is to obtain a battery capable of effectively reducing heat generation of external terminals.

Means for Solving the Problems

[0006] The battery according to claim 1 comprises an electrode body equipped with a current collector, a case housing the electrode body, a current collector terminal provided inside the case and joined to the current collector, and a plurality of external terminals electrically connected to the current collector terminal, wherein two external terminals are arranged along one direction of the case, the current collector and the current collector terminal are joined between the two external terminals and outward in the one direction from each external terminal, and the length along the one direction of the region where the current collector and the current collector terminal are joined between the two external terminals is longer along the one direction from the region where the current collector and the current collector terminal are joined outward in the one direction from each external terminal.

[0007] In the battery according to claim 1, an electrode body is housed in a case, and a current collector terminal connected to a current collector is provided inside the case. It also has a plurality of external terminals, which are electrically connected to the current collector terminals. Two external terminals are arranged along one direction of the case. The current collector and the current collector terminal are connected between the two external terminals. Furthermore, the current collector and the current collector terminal are connected in one direction outward from each external terminal. The length in one direction of the region where the current collector and the current collector terminal are connected between the two external terminals is longer in one direction than the length in one direction of the region where the current collector and the current collector terminal are connected in one direction outward from each external terminal. This ensures sufficient distance between the external terminals while preventing them from being too close to the edges of the electrode body, thereby suppressing an increase in current density.

[0008] The battery according to claim 2, in claim 1, comprises two positive electrode external terminals provided on one end of the case and two negative electrode external terminals provided on the other end of the case.

[0009] In the battery according to claim 2, since there are two external terminals on both the positive and negative sides, an increase in current density can be suppressed on both the positive and negative sides.

[0010] The battery according to claim 3 comprises an electrode body equipped with a current collector, a case housing the electrode body, a current collector terminal provided inside the case and connected to the current collector, and a plurality of external terminals electrically connected to the current collector terminal, wherein three external terminals are arranged along one direction of the case, and when the length of the electrode body in that direction is d, the distance along that direction from the center of the electrode body in that direction to the external terminals at both ends is d / 3 ± 5 mm, and the spacing between the external terminals along that direction is d / 3 ± 5 mm.

[0011] In the battery according to claim 3, by having three external terminals, the current can be distributed more effectively than in the case of two external terminals, thereby suppressing an increase in current density. [Effects of the Invention]

[0012] As described above, the battery according to the present invention can effectively reduce heat generation at the external terminals. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic cross-sectional view of a battery according to the first 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 an enlarged cross-sectional view of the main part of the battery according to the second embodiment, showing an enlarged view of the main part. [Modes for carrying out the invention]

[0014] <First Embodiment> A battery (also called a battery cell) according to the first embodiment will be described with reference to the drawings. Figure 1 is a schematic cross-sectional view of a battery 10 as a battery according to the embodiment. For example, the battery 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).

[0015] Furthermore, the battery 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).

[0016] The battery 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 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.

[0017] The peripheral wall portion 12A is formed of 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.

[0018] Figure 2 is a cross-sectional view showing the state when cut along line 2-2 in Figure 1. As shown in Figure 2, the electrode body 14 is composed of a positive electrode current collector 40 and a negative electrode current collector 48. Specifically, the electrode body 14 is composed of stacking the positive electrode current collector 40, positive electrode composite material 42, solid electrolyte 44, negative electrode composite material 46, and negative electrode current collector 48 in that order. Note that in Figure 2, for the sake of explanation, a state in which two layers of positive electrode current collector 40 and one layer of negative electrode current collector 48 are stacked is shown, but in reality, many more positive electrode current collectors 40 and negative electrode current collectors 48 are stacked.

[0019] The negative electrode 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 electrode current collector 48.

[0020] The negative electrode composite material 46 is coated on both surfaces of the negative electrode current collector 48. The negative electrode composite material 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), 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. Artificial graphite is preferable as the negative electrode active material.

[0021] The solid electrolyte 44 is laminated on the side of the negative electrode composite material 46 opposite to the negative electrode current collector 48. Further, the positive electrode composite material 42 is laminated on the side of the solid electrolyte 44 opposite to the negative electrode composite material 46. 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, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, Li(NiCoMn)O2, Li(NiCoAl)O2, and LiFePO4 can be mentioned as the positive electrode active material. Note that the positive electrode active material particles may be Hi-Nickel (positive electrode active material with a high ratio of Ni) or a Li-Ni-Co-Mn-based composite oxide or a ternary positive electrode active material.

[0022] The positive electrode current collector 40 is formed of a metal foil, and an aluminum foil is preferable as the positive electrode current collector 40. Thus, as an example, the electrode body 14 of the present embodiment has a structure in which 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, so the number of positive electrode current collectors 40 is larger than that of the negative electrode current collector 48.

[0023] As shown in Figure 1, the electrode body 14 has a longitudinal direction and a transverse direction when viewed from the stacking direction. A positive electrode tab 16 extends from one end of the electrode body 14 in the longitudinal direction, and a negative electrode tab 18 extends from the other end in the longitudinal direction. In the following description, the transverse direction of the electrode body 14 may be referred to as the width direction.

[0024] The positive electrode tab 16 is formed by collecting positive electrode foils extending from multiple positive electrode current collectors 40 that constitute the electrode body 14. In this embodiment, as an example, it is divided into three parts: a first positive electrode tab 16A, a second positive electrode tab 16B, and a third positive electrode tab 16C.

[0025] The first positive electrode tab 16A extends from a corner on one end of the electrode body 14 in the width direction toward the positive electrode side cover portion 12B and is joined to the first current collection 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 portion 12B and is joined to the first current collection terminal 20. Furthermore, the third positive electrode tab 16C extends from a corner on the other end of the electrode body 14 in the width direction toward the positive electrode side cover portion 12B and is joined to the first current collection terminal 20.

[0026] 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.

[0027] The first negative electrode tab 18A extends from a corner on 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, 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 portion 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 a corner on the other 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, which will be described later.

[0028] 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.

[0029] 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.

[0030] In this embodiment, the positive electrode side cover portion 12B of the case 12 is provided with a plurality of positive electrode side external terminals 28, and the negative electrode side cover portion 12C is provided with a plurality of negative electrode side external terminals 30. As an example in this embodiment, the positive electrode side cover portion 12B is provided with two positive electrode side external terminals 28 along one direction of the case 12. Also, the negative electrode side cover portion 12C is provided with two negative electrode side external terminals 30 along one direction of the case 12.

[0031] The positive electrode external terminal 28 is located at a position that divides the positive electrode cover portion 12B into approximately three equal parts, and the negative electrode external terminal 30 is located at a position that divides the negative electrode cover portion 12C into approximately three equal parts. Therefore, in this embodiment, as an example, the positive electrode external terminal 28 and the negative electrode external terminal 30 are located at positions that face each other. The details of the positive electrode external terminal 28 will be described below, but the negative electrode external terminal 30 has a similar configuration.

[0032] 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 positive electrode side 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.

[0033] 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 positive electrode side external terminal 28 is exposed to the outside of the case 12.

[0034] A resin component 32 is interposed between the positive electrode external terminal 28 and the positive electrode cover portion 12B. The resin component 32 is provided on the hole wall and edge of the insertion hole formed in the positive electrode cover portion 12B, and further covers the circumferential surface of the external flange portion 28B of the positive electrode external terminal 28. Thus, the resin component 32 insulates the positive electrode external terminal 28 from the positive electrode cover portion 12B.

[0035] The internal flange portion 28C of the positive electrode external terminal 28 bites into the first current collection terminal 20, and the first current collection terminal 20, the first insulating member 24, and the positive electrode side cover portion 12B are sandwiched between the positive electrode external terminal 28. In other words, the positive electrode external terminal 28 is fixed with the first insulating member 24 sandwiched between the case 12 and the first current collection terminal 20. The positive electrode 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.

[0036] Furthermore, since the positive electrode 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 positive electrode external terminal 28 via the first current collection terminal 20.

[0037] As shown in Figure 1, the negative electrode external terminal 30, like the positive electrode external terminal 28, is constructed using a crimping member and is formed by crimping it while it is inserted into the negative electrode cover portion 12C. That is, the negative electrode external terminal 30 is fixed with the second insulating member 26 sandwiched between the case 12 and the second current collection terminal 22. The negative electrode external terminal 30 is insulated from the negative electrode 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 negative electrode external terminal 30 via the second current collection terminal 22.

[0038] Furthermore, in this embodiment, the electrode body 14 is connected to the first current collection terminal 20 on both sides of the positive electrode side external terminal 28 when viewed from the stacking direction, and connected to the second current collection terminal 22 on both sides of the negative electrode side external terminal 30. Specifically, the first positive electrode tab 16A and the second positive electrode tab 16B are arranged on either side of one positive electrode side external terminal 28, and the second positive electrode tab 16B and the third positive electrode tab 16C are arranged on either side of the other positive electrode side external terminal 28. In other words, the positive electrode side external terminal 28 and the positive electrode tabs 16 are alternately connected to the first current collection terminal 20 along one direction.

[0039] Furthermore, the first negative electrode tab 18A and the second negative electrode tab 18B are arranged on either side of one negative electrode 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 negative electrode external terminal 30. In other words, the negative electrode external terminals 30 and the negative electrode tabs 18 are alternately connected to the second current collection terminal 22 along one direction.

[0040] 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 tab 16 and the first current collector terminal 20 are joined in most of the region except for the portion where the positive electrode side external terminal 28 is provided.

[0041] 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 negative electrode side external terminal 30 is provided.

[0042] Furthermore, as shown in Figure 3, if the length of the electrode body 14 in the width direction (one direction) is d, the distance Q1 along one direction from the center of the electrode body 14 in the width direction to the positive electrode side external terminal 28 satisfies the following equation (1). Here, distance Q1 is the distance between the center of the electrode body 14 and the center of the positive electrode side external terminal 28.

[0043]

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[0044] Furthermore, the distance P1 between adjacent positive external terminals 28 satisfies the following equation (2). Here, the distance P1 is the distance from the center of one positive external terminal 28 to the center of the other positive external terminal 28.

[0045]

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[0046] In this embodiment, as shown in Figure 1, the positive electrode external terminal 28 and the negative electrode external terminal 30 are positioned opposite each other. Therefore, the negative electrode external terminal 30 is also positioned to satisfy equations (1) and (2) above.

[0047] (action) Next, the operation of the battery 10 according to this embodiment will be explained.

[0048] In the battery 10 according to this embodiment, as shown in Figure 1, the electrode body 14 is housed in a case 12, and inside the case 12 are a first current collector terminal 20 connected to a positive electrode current collector 40 and a second current collector terminal 22 connected to a negative electrode current collector 48. The battery 10 also has a plurality of positive electrode external terminals 28 and negative electrode external terminals 30, with the positive electrode external terminals 28 and the first current collector terminal 20 being electrically connected, and the negative electrode external terminals 30 and the second current collector terminal 22 being electrically connected.

[0049] Here, as shown in Figure 3, two positive electrode external terminals 28 are arranged along one direction of the case 12. Furthermore, if the length of the electrode body 14 in one direction is d, the distance Q1 along that direction from the center of the electrode body 14 in one direction to the positive electrode external terminal 28 satisfies equation (1), and the spacing P1 of the positive electrode external terminals 28 along that direction satisfies equation (2). This makes it possible to suppress an increase in current density.

[0050] In other words, if the position of the positive electrode external terminal 28 does not satisfy equation (1) and is greater than d / 4+5(mm), the positive electrode external terminal 28 is too close to the edge of the electrode body 14, which may increase the current density. Also, if the position of the positive electrode external terminal 28 does not satisfy equation (1) and is less than d / 4-5(mm), the positive electrode external terminal 28 is too close to the center of the electrode body 14, which may increase the current density.

[0051] Furthermore, if the position of the positive external terminal 28 does not satisfy equation (2) and falls outside the range of d / 2 + 5 (mm), the distance between the two positive external terminals 28 may be too narrow or too far apart, potentially increasing the current density.

[0052] Thus, in this embodiment, by optimizing the position of the positive electrode external terminal 28, the current density can be reduced, and the heat generated at the positive electrode external terminal 28 can be effectively reduced. The same applies to the negative electrode external terminal 30.

[0053] Furthermore, in this embodiment, since the positive electrode external terminal 28 and the positive electrode tab 16 are alternately connected to the first current collection terminal 20, an imbalance in current density can be suppressed. In particular, in this embodiment, two positive electrode external terminals 28 and two negative electrode external terminals 30 are provided, and since the negative electrode external terminals 30 and the negative electrode tab 18 are alternately connected to the second current collection terminal 22, an increase in current density can be suppressed on both the positive and negative sides.

[0054] <Second Embodiment> The battery according to the second embodiment will be described with reference to Figure 4. Components similar to those in the first embodiment are denoted by the same reference numerals, and their descriptions are omitted as appropriate.

[0055] The battery 50 of this embodiment differs from the first embodiment in that the number of external terminals has increased. Specifically, the positive electrode side external terminals 28 constituting the battery 50 are arranged in three in a unidirectional manner along the case 12.

[0056] The positive electrode external terminals 28 are positioned to divide the electrode body 14 into approximately four equal parts. Each positive electrode external terminal 28 is composed of a shaft portion 28A, an external flange portion 28B, and an internal flange portion 28C.

[0057] Furthermore, the positive electrode tab 16 in this embodiment is divided into four parts: a first positive electrode tab 16A, a second positive electrode tab 16B, a third positive electrode tab 16C, and a fourth positive electrode tab 16D. Here, the first positive electrode tab 16A and the second positive electrode tab 16B are arranged on either side of the positive electrode external terminal 28, and the second positive electrode tab 16B and the third positive electrode tab 16C are arranged on either side of the central positive electrode external terminal 28. Furthermore, the third positive electrode tab 16C and the fourth positive electrode tab 16D are arranged on either side of the positive electrode external terminal 28 on the other side. In other words, along one direction, the positive electrode external terminal 28 and the positive electrode tabs 16 are alternately connected to the first current collection terminal 20.

[0058] Furthermore, in this embodiment, if the length of the electrode body 14 in one direction is d, the distance Q2 along one direction from the center of the electrode body 14 to the positive electrode side external terminals 28 at both ends satisfies the following equation (3). Here, distance Q2 is the distance connecting the center of the electrode body 14 and the center of the positive electrode side external terminals 28.

[0059]

number

[0060] Furthermore, the distance P2 between the positive external terminals 28 at both ends satisfies the following equation (4). Here, the distance P2 is the distance from the center of one positive external terminal 28 to the center of the other positive external terminal 28.

[0061]

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[0062] (action) Next, the operation of the battery 50 according to this embodiment will be explained.

[0063] In the battery 50 according to this embodiment, by having three positive electrode external terminals 28, the current can be distributed more effectively than when there are two positive electrode external terminals 28, thereby suppressing an increase in current density. Other functions are the same as in the first embodiment. Similarly, three negative electrode external terminals may also be provided.

[0064] Although a battery according to an embodiment has been described above, it is important to note that 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 embodiment, as shown in Figure 1, the external terminals and current collection tabs were alternately connected to the current collection terminals, but the invention is not limited thereto.

[0065] Furthermore, in the above embodiment, the number of positive and negative external terminals is the same, but this is not limited to this. For example, the number of positive external terminals may be two and the number of negative external terminals may be three. [Explanation of symbols]

[0066] 10, 50 batteries 12 cases 14 Electrode body 16 Positive Tab 18 Negative Electrode Tabs 20 1st current collector terminal 22 2nd current collector terminal 28 Positive side external terminal 30 Negative side external terminal

Claims

1. An electrode body equipped with a current collector, A case for housing the electrode body, A current collection terminal is provided inside the case and connected to the current collector, Multiple external terminals electrically connected to the current collection terminal, It has, The external terminals are arranged in pairs along one direction of the case, The current collector and the current collector terminals are joined between the two external terminals and outward in one direction from each of the external terminals. The length in one direction of the region where the current collector and the current collector terminal are joined between the two external terminals is longer in one direction than the length in one direction of the region where the current collector and the current collector terminal are joined outside of each external terminal. battery.

2. The battery according to claim 1, wherein the external terminals include two positive-side external terminals provided on one end of the case and two negative-side external terminals provided on the other end of the case.

3. An electrode body equipped with a current collector, A case for housing the electrode body, A current collection terminal is provided inside the case and connected to the current collector, Multiple external terminals electrically connected to the current collection terminal, It has, The external terminals are arranged in three positions along one direction of the case. When the length of the electrode body in one direction is d, the distance along one direction from the center of the electrode body in one direction to the external terminals at both ends is d / 3 ± 5 mm. The spacing between the external terminals along one direction is d / 3 ± 5 mm. battery.

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