Battery

Abstract

The invention provides a battery. The present invention is characterized by having a laminate formed by laminating, in a predetermined lamination direction, a plurality of electrodes having a current collector and at least one of a positive electrode active material layer and a negative electrode active material layer formed on the current collector, and a plurality of separators positioned between the positive electrode active material layer and the negative electrode active material layer, a portion of the current collector is a current collector foil in which the positive electrode active material layer and the negative electrode active material layer are not formed, and when the laminate is viewed in the lamination direction, an outer peripheral end portion of the current collector foil located at a central portion in the lamination direction is located further toward the outer peripheral side than an outer peripheral end portion of the current collector foil located at an end portion in the lamination direction.

Description

Technical Field

[0001] The present invention relates to batteries. Background Art

[0002] In Japanese Patent Application Laid-Open No. 2017-168266 described below, a battery is disclosed in which a plurality of electrodes including bipolar electrodes are stacked in a predetermined stacking direction. Summary of the invention

[0003] When the battery of Japanese Patent Application Laid-Open No. 2017-168266 receives a load from a conductive member in a direction perpendicular to the stacking direction, there is a possibility that an external short circuit with high heat may occur between the collector foils of the plurality of collectors.

[0004] The present invention has been made in consideration of the above facts, and an object of the present invention is to provide a battery in which external short circuits caused by high heat are unlikely to occur between the collector foils of a plurality of collectors when a load in a direction perpendicular to the stacking direction of the plurality of electrodes is applied from a conductive member.

[0005] A battery according to a first aspect includes a laminated body.

[0006] The stacked body is formed by stacking a plurality of electrodes including a current collector and at least one of a positive electrode active material layer and a negative electrode active material layer formed on the current collector, and a plurality of separators located between the positive electrode active material layer and the negative electrode active material layer in a predetermined stacking direction.

[0007] A portion of the current collector is a current collector foil on which the positive electrode active material layer and the negative electrode active material layer are not formed.

[0008] When the stacked body is viewed along the stacking direction, the outer peripheral end of the collector foil located in the center of the stacking direction is located more outer peripherally than the outer peripheral end of the collector foil located at the end in the stacking direction.

[0009] In the battery of the first embodiment, when the stack is observed along the stacking direction of the stack, the outer peripheral end of the collector foil located in the center of the stacking direction is located closer to the outer peripheral side than the outer peripheral end of the collector foil located at the end of the stacking direction. Therefore, when the battery receives a load in a direction orthogonal to the stacking direction from the conductive member, the conductive member is less likely to contact the collector foil located in the center and the collector foil located at the end of the stacking direction at the same time. In other words, in the battery of the first embodiment, it is difficult for the collector foils of the multiple collectors to have an external short circuit with large heat.

[0010] The battery of the second aspect is characterized in that in the first aspect,

[0011] The electrodes other than the electrodes located at the ends in the stacking direction are bipolar electrodes including the current collector, the positive electrode active material layer formed on one surface of the current collector, and the negative electrode active material layer formed on the other surface of the current collector.

[0012] The battery of the second aspect can output greater electric power than a battery without bipolar electrodes.

[0013] A battery according to a third aspect is a battery according to the first aspect or the second aspect,

[0014] The outer peripheral end portion of the collector foil located at the center in the stacking direction is located further toward the outer peripheral side than the outer peripheral end portion of the collector foil located at an end portion in the stacking direction.

[0015] In the battery of the third embodiment, the outer peripheral end of the collector foil located in the center of the stacking direction is located closer to the outer peripheral side than the outer peripheral end of the collector foil located at the end of the stacking direction. According to this structure, the conductive member contacting the collector foil located in the center is difficult to contact the collector foils located at the two end portions in the stacking direction.

[0016] In addition, when the total number of current collectors is an odd number, the "collector foil located in the center" is the collector foil of one current collector, and when the total number of current collectors is an even number, the "collector foil located in the center" is the collector foil of two current collectors. Furthermore, when the total number of current collectors is an even number, the outer peripheral side end of the collector foil of the two current collectors may be located closer to the outer peripheral side than the outer peripheral side end of the collector foil located at the end in the stacking direction. Alternatively, the outer peripheral side end of the collector foil of only one of the two current collectors may be located closer to the outer peripheral side than the outer peripheral side end of the collector foil located at the end in the stacking direction.

[0017] A battery according to a fourth aspect is a battery according to the first aspect or the second aspect,

[0018] When the stacked body is viewed along the stacking direction, a distance between the outer peripheral side ends of the collector foils adjacent to each other in the stacking direction is larger than a dimension of the collector in the stacking direction.

[0019] According to the fourth aspect, when a load in a direction perpendicular to the stacking direction is received from the conductive member, external short circuit is unlikely to occur between the collector foils adjacent to each other in the stacking direction.

[0020] The battery according to the fifth aspect is, in the first aspect or the second aspect,

[0021] When the current collector having the outer peripheral side end portion located on the outermost peripheral side when the stacked body is viewed along the stacking direction is defined as the largest protruding current collector,

[0022] Each of the current collectors other than the largest protruding current collector has an outer peripheral end portion located on the inner peripheral side than the outer peripheral end portion of the current collector foil of the current collector located on the largest protruding current collector side.

[0023] According to the fifth aspect, when a load in a direction perpendicular to the stacking direction is received from the conductive member, an external short circuit is unlikely to occur between the collector foils.

[0024] As described above, the battery according to the present invention has an excellent effect that when a load in a direction perpendicular to the stacking direction of the plurality of electrodes is received from a conductive member, an external short circuit with high heat is unlikely to occur between the collector foils of the plurality of collectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0026] Figure 1 It is a schematic perspective view of a bipolar lithium ion secondary battery according to an embodiment.

[0027] Figure 2 It is along Figure 1 Schematic cross-sectional view of the 2-2 line.

[0028] Figure 3 This is a schematic cross-sectional view of a stacked body and a conductive member when an external short circuit occurs due to collision of a conductive member with a lithium-ion secondary battery. DETAILED DESCRIPTION

[0029] The following describes a bipolar lithium-ion secondary battery (hereinafter referred to as battery 10) according to an embodiment. Battery 10 can be mounted on various devices. Battery 10 according to this embodiment is mounted on a battery electric vehicle (BEV) and can supply power to an electric motor as a driving source. In addition, arrows UP, FR, and LH in the drawings respectively indicate the upper side in the up-down direction, the front side in the front-back direction, and the left side in the left-right direction.

[0030] First, a basic structure of the battery 10 will be described. The battery 10 of the present embodiment includes a laminate 15 and a resin member 30 .

[0031] The stacked body 15 is formed by stacking in a predetermined stacking direction ( Figure 1 The structure is composed of a plurality of electrodes and a plurality of spacers 25 stacked in the vertical direction. Figure 2As shown in FIG. 1 , these electrodes include a negative terminal electrode 17, a positive terminal electrode 20, and a plurality of bipolar electrodes 23. The stack 15 of this embodiment includes 11 electrodes (negative terminal electrode 17, positive terminal electrode 20, bipolar electrodes 23). That is, the stack 15 has 11 current collectors 18. Figure 2 as well as Figure 3 In the figure, illustration of a part of the bipolar electrodes 23 is omitted.

[0032] The negative terminal electrode 17 includes a current collector 18 and a Figure 1 The positive terminal electrode 20 includes a current collector 18 and a negative electrode active material layer 19 disposed on one side of the current collector 18 ( Figure 1 The positive electrode active material layer 21 is provided on the lower surface of the current collector 18. Each bipolar electrode 23 includes a current collector 18 and a positive electrode active material layer 21 provided on one side of the current collector 18 ( Figure 2 The negative electrode active material layer 19 is provided on the upper surface of the current collector 18, and the negative electrode active material layer 19 is provided on the other surface of the current collector 18 ( Figure 2 The positive electrode active material layer 21 has a lower surface.

[0033] A separator 25 is provided between the negative active material layer 19 of the negative terminal electrode 17 and the positive active material layer 21 of the bipolar electrode 23 adjacent to the negative terminal electrode 17. Furthermore, a separator 25 is provided between the positive active material layer 21 of the positive terminal electrode 20 and the negative active material layer 19 of the bipolar electrode 23 adjacent to the positive terminal electrode 20. Furthermore, a separator 25 is provided between the negative active material layer 19 of the adjacent bipolar electrode 23 and the positive terminal electrode 20.

[0034] like Figure 1 as well as Figure 2 As shown in FIG. 1 , both end faces of the stacked body 15 including the negative terminal electrode 17, the positive terminal electrode 20, the bipolar electrode 23 and the separator 25 in the stacking direction are formed by the collector 18. Figure 2 As shown, the outer peripheral portion of each current collector 18 when the stacked body 15 is viewed along the stacking direction is the current collector foil 18 - 1 located on the outer peripheral side of the negative electrode active material layer 19 and the positive electrode active material layer 21 .

[0035] The shape (planar shape) of the stacked body 15 when viewed along the stacking direction of the present embodiment is a rectangle. That is, the shape of the current collector 18, the negative electrode active material layer 19, the positive electrode active material layer 21, and the separator 25 when viewed along the stacking direction of the stacked body 15 is a rectangle. Figure 2It can be seen that when the stacked body 15 is observed along the stacking direction, the outer peripheral end of each negative electrode active material layer 19 is located closer to the outer peripheral side than the outer peripheral end of each positive electrode active material layer 21. Furthermore, the shapes of the negative electrode active material layers 19 when the stacked body 15 is observed along the stacking direction are the same as each other, and the shapes of the positive electrode active material layers 21 when the stacked body 15 is observed along the stacking direction are the same as each other.

[0036] On the other hand, the shapes of the current collectors 18 when the stack 15 is viewed along the stacking direction are different from each other. Here, the current collector 18 located in the center of the stacking direction is defined as the most protruding current collector 18C. That is, the current collector 18 that is the sixth from the top and the sixth from the bottom is the most protruding current collector 18C. Figure 2 It can be seen that, regarding the shape (outer shape) when observed along the stacking direction, the largest protruding collector 18C is the largest among all the collectors 18, and the shape of each collector 18 gradually becomes smaller as it moves upward and downward from the largest protruding collector 18C. In other words, regarding the outer peripheral end 18PE of each collector 18, the outer peripheral end 18PE of each collector 18 gradually becomes closer to the inner peripheral side as it moves upward and downward from the largest protruding collector 18C. Furthermore, when observing the stack 15 along the stacking direction, the distance DF in the direction perpendicular to the stacking direction between the outer peripheral end 18PE of the collectors 18 adjacent to each other in the stacking direction (at Figure 2 The distance DF (only a portion of which is shown in the figure) is greater than the dimension (thickness) of each current collector 18 in the stacking direction. For example, the distance DF in the front-to-back direction between the front end face of the top current collector 18 and the front end face of the second current collector 18 from the top and the distance DF in the front-to-back direction between the front end face of the second current collector 18 from the bottom and the front end face of the third current collector 18 from the bottom are greater than the dimension of the current collector 18 in the stacking direction.

[0037] The shapes of the separators 25 when viewed along the stacking direction of the stack 15 are different from each other. That is, the shape of the separators 25 when viewed along the stacking direction is substantially the same as that of the current collector 18 facing the separator 25 from the side of the largest protruding current collector 18C. Furthermore, the outer peripheral end of each separator 25 is located further to the outer peripheral side than the outer peripheral end of the negative electrode active material layer 19 and the positive electrode active material layer 21.

[0038] A resin component 30 as an integrally molded resin product is provided at the periphery of the stack 15. The resin component 30 is integrated with the periphery of the stack 15 in an airtight and liquid-tight state in a manner that covers the periphery of the stack 15. The shape of the resin component 30 when cut along a section perpendicular to the stacking direction is a rectangle with a rectangular opening formed in the center. The resin component 30 is made of an insulating resin material. The constituent material of the resin component 30 is, for example, polypropylene, polyethylene, polystyrene, ABS resin, acid-modified polypropylene, acid-modified polyethylene, or acrylonitrile styrene resin. For example, the resin component 30 may be provided integrally at the periphery of the stack 15 by insert molding performed while the stack 15 is arranged inside a molding die (not shown).

[0039] Although not shown in the figure, an electrolyte is provided inside the stacked body 15 , and the negative terminal electrode 17 , the positive terminal electrode 20 , and the bipolar electrode 23 are impregnated with the electrolyte.

[0040] The battery 10 having the above-described structure is fixed, via fixing means, to the upper surface of a substantially horizontal plate member (not shown) forming a part of the vehicle body component of the battery-electric vehicle.

[0041] like Figure 1 as well as Figure 2 As shown, the outer peripheral end 18PE of each current collector 18 of the negative terminal electrode 17, the positive terminal electrode 20, and the bipolar electrode 23 and the outer peripheral end of each separator 25 are located inside the resin member 30. On the other hand, the outer peripheral end of each negative electrode active material layer 19 and each positive electrode active material layer 21 is located further inward than the inner peripheral surface of the central opening 30S of the resin member 30. Furthermore, the current collector 18 of the negative terminal electrode 17 is exposed through one opening end of the central opening 30S, and the current collector 18 of the positive terminal electrode 20 is exposed through the other opening end of the central opening 30S. Therefore, the electric power generated by the battery 10 can be supplied to various electrical devices and electronic devices (omitted from the illustration) provided in the above-mentioned battery electric vehicle through a conductive component (omitted from the illustration) connected to the collector 18 of the negative terminal electrode 17 via the opening end of one side of the central opening portion 30S and a conductive component (omitted from the illustration) connected to the collector 18 of the positive terminal electrode 20 via the opening end of the other side of the central opening portion 30S.

[0042] Function and effect

[0043] Next, the operation and effects of this embodiment will be described.

[0044] Here, it is assumed that a vehicle (not shown) traveling forward in the rear area of ​​the battery-electric vehicle collides with the rear end of the battery-electric vehicle. Figure 3 As shown, the battery electric vehicle includes a metal component (conductive component) 40 which is a part of the vehicle body component and is located immediately after the battery 10. At a time point before the battery electric vehicle collides, the front end surface 41 of the component 40 is composed of a plane orthogonal to the front-rear direction. Furthermore, the lower end of the component 40 is located lower than the lower end of the battery 10, the upper end of the component 40 is located higher than the upper end of the battery 10, the left end of the component 40 is located to the left of the left end of the battery 10, and the right end of the component 40 is located to the right of the right end of the battery 10.

[0045] When such a collision occurs in the battery-electric vehicle, the component 40 may move forward relative to the battery 10 due to the impact generated in the battery-electric vehicle. In addition, the component 40 may damage the rear portion 30R of the resin component 30 (see Figure 1 , Figure 2 ) and collides with the rear end (outer peripheral end) of the stack 15. Figure 3 3, while omitting the rear portion 30R (resin component 30), the rear portion of the laminate 15 and the component 40 when such a state occurs in the battery electric vehicle are shown.

[0046] In this case, if Figure 3 The front end surface 41 of the component 40 shown contacts the rear end portion (outer peripheral end portion 18PE) of the largest protruding collector 18C of the bipolar electrode 23 located at the center in the stacking direction. Furthermore, the front end surface 41 contacts the rear end portion (outer peripheral end portion) of the spacer 25 facing from above the largest protruding collector 18C and the rear end portion (outer peripheral end portion 18PE) of the collector 18, i.e., the collector 18U, facing from above the spacer 25. Furthermore, the front end surface 41 contacts the rear end portion (outer peripheral end portion) of the spacer 25 facing from below the largest protruding collector 18C and the rear end portion (outer peripheral end portion 18PE) of the collector 18, i.e., the collector 18D, facing from below the spacer 25.

[0047] However, as described above, the outer peripheral end 18PE of each current collector 18 is gradually located closer to the inner peripheral side as one moves upward and downward from the most protruding current collector 18C. That is, the rear end of each current collector 18 is gradually located closer to the front as one moves upward and downward from the most protruding current collector 18C. Therefore, in this case, it is difficult for the front end surface 41 to contact the rear end of each current collector 18 located higher than the current collector 18U and the rear end of each current collector 18 located lower than the current collector 18D. That is, in this case, there is a high possibility that the most protruding current collector 18C and the two current collectors 18U and 18D located above and below the most protruding current collector 18C are externally short-circuited via the conductive component 40. In this case, although the most protruding current collector 18C and the current collectors 18U and 18D generate heat, the possibility that the heat becomes a large amount of heat is low. That is, for example, when the member 40 contacts the largest protruding collector 18C located in the center of the stacking direction and the current collector 18 located at the top or bottom at the same time, these current collectors 18 generate extremely large amounts of heat. In contrast, when the largest protruding collector 18C and the two current collectors 18U and 18D located above and below the largest protruding collector 18C are externally short-circuited, the heat generated by the battery 10 is smaller than the heat generated when the largest protruding collector 18C located in the center and the current collector 18 located at the top or bottom are externally short-circuited. That is, in the battery 10 of the present embodiment, it is difficult for the current collector foils 18-1 of the plurality of current collectors 18 to have an external short circuit with large amounts of heat.

[0048] Furthermore, when the stack 15 is observed along the stacking direction, the distance DF between the outer peripheral ends 18PE of the current collectors 18 adjacent in the stacking direction is greater than the dimension (thickness) of the current collectors 18 in the stacking direction. That is, the distance between the outer peripheral ends 18PE of the current collectors 18 adjacent in the stacking direction is large. Therefore, compared with the case where the distance DF between the outer peripheral ends 18PE of the adjacent current collectors 18 is less than the dimension (thickness) of the current collectors 18 in the stacking direction, the possibility of the component 40 (front end surface 41) contacting the outer peripheral ends 18PE of multiple (for example, 4 or more) current collectors 18 at the same time is small.

[0049] Furthermore, since the battery 10 includes the bipolar electrodes 23, the battery 10 can generate a large amount of power compared to a case where the bipolar electrodes 23 are not included. That is, each bipolar electrode 23 can generate a large current (e.g., 5 A or more), so the degree of temperature rise of the battery 10 when an external short circuit occurs is higher than when an external short circuit occurs in a battery without bipolar electrodes. Therefore, when the present invention is applied to the battery 10, greater usefulness is obtained compared to a case where the present invention is applied to a battery without bipolar electrodes 23.

[0050] As mentioned above, the battery 10 according to the embodiment has been described, but the design thereof can be appropriately changed within the scope not departing from the gist of the present invention.

[0051] For example, the outer peripheral end portions 18PE of two current collectors 18 adjacent to each other in the stacking direction may overlap each other in the vertical direction when the stacked body 15 is viewed in the stacking direction.

[0052] The outer peripheral end 18PE of the current collector 18 located in the center of the stacking direction may be located at the outermost side among all the current collectors 18. Here, the "center" refers to the range between the N / 3rd current collector 18 from the top and the N / 3rd current collector 18 from the bottom when the total number of current collectors 18 is N. For example, as described in the present embodiment, when the battery 10 has 11 current collectors 18, N / 3=3.666... ​​In this case, the outer peripheral end 18PE of at least one current collector 18 located in any range between the fourth current collector 18 from the top and the fourth current collector 18 from the bottom is located at the outermost side. In addition, for example, when the battery 10 includes 18 current collectors 18, the outer peripheral end 18PE of the current collector 18 located in any range between the sixth current collector 18 from the top and the sixth current collector 18 from the bottom is located at the outermost side. In this modification, the possibility that the component 40 simultaneously contacts the current collector 18 having the outer peripheral end 18PE located at the outermost side and the current collector 18 located at the top or the bottom is also small.

[0053] As long as the outer peripheral end 18PE of at least one collector 18 located in the center of the stacking direction is located closer to the outer peripheral side than the outer peripheral end 18PE of the collector 18 located at the end in the stacking direction, the outer peripheral end 18PE of other collectors 18 may also be located closer to the inner peripheral side than the outer peripheral end 18PE of the collector 18 located at the end in the stacking direction.

[0054] The number of electrodes provided in the battery 10 may be any as long as it is plural.

[0055] All electrodes provided in the battery 10 may be constituted by electrodes other than bipolar electrodes.

[0056] The battery 10 may have a structure in which the stacked body is covered with a container made of a laminate film.

[0057] The battery 10 may be provided in a device different from the battery electric vehicle.

Claims

1. A battery comprising a laminate, The stacked body is formed by stacking a plurality of electrodes including a current collector and at least one of a positive electrode active material layer and a negative electrode active material layer formed on the current collector, and a plurality of separators located between the positive electrode active material layer and the negative electrode active material layer in a predetermined stacking direction. A portion of the current collector is a current collector foil on which the positive electrode active material layer and the negative electrode active material layer are not formed. When the stacked body is viewed along the stacking direction, the outer peripheral end of the collector foil located in the center of the stacking direction is located more outer peripherally than the outer peripheral end of the collector foil located at the end in the stacking direction.

2. The battery according to claim 1, wherein The electrodes other than the electrodes located at the ends in the stacking direction are bipolar electrodes including the current collector, the positive electrode active material layer formed on one surface of the current collector, and the negative electrode active material layer formed on the other surface of the current collector.

3. The battery according to claim 1 or 2, wherein: The outer peripheral end portion of the collector foil located at the center in the stacking direction is located further toward the outer peripheral side than the outer peripheral end portion of the collector foil located at the end portion in the stacking direction.

4. The battery according to claim 1 or 2, wherein: When the stacked body is viewed along the stacking direction, a distance between the outer peripheral side ends of the collector foils adjacent to each other in the stacking direction is larger than a dimension of the collector in the stacking direction.

5. The battery according to claim 1 or 2, wherein: When the current collector having the outer peripheral side end portion located on the outermost peripheral side when the stacked body is viewed along the stacking direction is defined as the largest protruding current collector, Each of the current collectors other than the largest protruding current collector has an outer peripheral end portion located on the inner peripheral side than the outer peripheral end portion of the current collector foil of the current collector located on the largest protruding current collector side.

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