Battery stack

Abstract

To solve such a problem that, in conventional secondary batteries, a cooling efficiency of a battery cell disposed near a terminal portion of a duct among cooling efficiencies of battery cells included in a battery stack is low.SOLUTION: In a battery stack of the present invention, spacers 31, 32 each have: an air inlet of cooling air blown through a duct; a first air exit exhausting the cooling air supplied from the air inlet; and a second air exit exhausting the cooling air supplied from the air inlet. The plurality of spacers include: a first spacer 3 in which a first flow path connecting the air inlet and the first air exit and a second flow path connecting the air inlet and the second air exit are formed symmetrically; and a second spacer 4 in which the first flow path and the second flow path are formed asymmetrically. The plurality of first spacers 3 are disposed on a side of a blowing port for blowing the cooling air to the duct in the battery stack, and the plurality of second spacers 4 are disposed on a duct terminal portion side on the opposite side of the blowing port of the duct in the battery stack.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a battery stack in which, for example, a plurality of battery cells and spacers are stacked alternately. [Background technology]

[0002] When constructing an assembled battery by combining a large number of non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries, a battery stack is formed by stacking a plurality of secondary batteries, and this battery stack is housed in a stack case. In addition, in the assembled battery, cooling air may be supplied into the stack case to cool each battery cell of the battery stack. In addition, when cooling with such cooling air is performed, a duct is provided in the stack case, and cooling air is supplied to each battery cell through this duct. Therefore, an example of a technology related to a spacer that cools the battery cells with cooling air supplied from the duct is disclosed in Patent Document 1.

[0003] The temperature adjustment structure for an energy storage device described in Patent Document 1 is a temperature adjustment structure for an energy storage device in which a plurality of energy storage elements are stacked in a predetermined direction, and includes a pair of end plates that sandwich the plurality of energy storage elements in the predetermined direction, and spacers that are stacked alternately with the energy storage elements and form a space for cooling air to flow, the spacers each having an inlet and an outlet for the cooling air for the space, and a first spacer among the spacers that is disposed between the end plate and the energy storage element adjacent to at least the end plate in the predetermined direction has a guide portion at at least one of the inlet and the outlet that extends toward the inside of the opening so that the opening is not blocked. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-91665 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the airflow in the duct provided in the stack case is rectified as it approaches the end. This rectification of the airflow in the duct increases the pressure loss of the cooling air flowing toward the spacer near the end of the duct, causing a problem of reduced cooling efficiency for the battery cells arranged near the end of the duct. Patent Document 1 has the problem of being unable to solve the reduced cooling efficiency caused by this increased pressure loss.

[0006] The present invention has been made in consideration of the above circumstances, and aims to improve the cooling efficiency of the battery cells included in a battery stack, especially those that are arranged near the end portion of a duct. [Means for solving the problem]

[0007] One aspect of a battery stack according to the present invention is a battery stack in which a plurality of battery cells and spacers are alternately stacked, wherein each of the spacers has an air inlet provided on a first side facing a duct provided in a stack case for cooling air to be blown through the duct, a first exhaust port provided on a second side perpendicular to the first side for discharging the cooling air supplied from the air inlet, and a second exhaust port provided on a third side perpendicular to the first side and opposite to the second side for discharging the cooling air supplied from the air inlet, and the plurality of spacers a first spacer in which a first flow path connecting the air inlet and the first exhaust port and a second flow path connecting the air inlet to the second exhaust port are formed symmetrically, and a second spacer in which a first flow path connecting the air inlet and the first exhaust port and a second flow path connecting the air inlet to the second exhaust port are formed asymmetrically, wherein a plurality of the first spacers are arranged on the air outlet side of the battery stack that sends the cooling air into the duct, and a plurality of the second spacers are arranged on the duct end side opposite the air outlet of the duct. Effect of the Invention

[0008] According to the secondary battery of the present invention, it is possible to improve the cooling efficiency of the battery cells arranged near the end portions of the ducts, among the cooling efficiency of the battery cells included in the battery stack. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a battery stack according to a first embodiment. [Diagram 2] 5 is a diagram illustrating a flow path of cooling air in the first spacer according to the first embodiment. FIG. [Diagram 3] 6 is a diagram illustrating a flow path of cooling air in the second spacer according to the first embodiment. FIG. [Figure 4] FIG. 2 is a diagram illustrating a duct according to the first embodiment. [Diagram 5] FIG. 4 is another diagram illustrating the duct according to the first embodiment. [Figure 6] FIG. 4 is a diagram illustrating the flow of cooling air in a duct according to the first embodiment. [Figure 7] 5A and 5B are diagrams explaining the flow of cooling air branched off from a duct to a spacer arranged between battery cells housed in the stack case according to the first embodiment. [Figure 8] 10A and 10B are diagrams illustrating the flow of cooling air in a duct according to a comparative example. [Figure 9] 11 is a diagram illustrating the flow of cooling air branched off from a duct to a spacer arranged between battery cells housed in a stack case according to a comparative example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In order to clarify the description, the following description and drawings are omitted and simplified as appropriate. In each drawing, the same elements are given the same reference numerals, and repeated description is omitted as necessary. In the following description, the direction in which the battery stacks are arranged in the stack case is defined as the width direction X, the direction in which the battery cells and spacers are stacked when constructing the battery stack is defined as the stacking direction Y, and the direction perpendicular to the width direction X and the stacking direction Y, which is the height of the battery stack, is defined as the height direction Z. The width direction X and the stacking direction Y coincide with the horizontal direction when the battery stack is placed in the stack case, and the height direction Z coincides with the vertical direction. In the following description, the width direction X may be referred to as the left-right direction, the height direction Z may be referred to as the up-down direction, and the stacking direction may be referred to as the depth direction. In the following description, the combination of the battery stack and the stack case may be referred to as a secondary battery.

[0011] First embodiment Fig. 1 shows a schematic diagram of a battery stack 1 according to the first embodiment. As shown in Fig. 1, the battery stack 1 according to the first embodiment has a plurality of battery cells 2 and spacers stacked alternately. Here, in the battery stack 1 according to the first embodiment, two types of spacers, a first spacer and a second spacer 4, are used as the spacers to be combined with the battery cells 2. Also, in the battery stack 1 according to the first embodiment, the first spacer 3 is arranged on the air outlet side of a duct, which will be described later, and the second spacer 4 is arranged on the end side of a flow path formed by the duct.

[0012] Next, the first spacer 3 and the second spacer 4 will be described in detail. The first spacer 3 and the second spacer 4 have different flow path shapes. Note that the shape of the ribs formed on the spacers to configure the flow paths shown below is an example and is not limited to this.

[0013] FIG. 2 is a diagram for explaining the flow path of the cooling air of the first spacer 3 according to the first embodiment. As shown in FIG. 2, the first spacer 3 has an air inlet 5, a first exhaust port 6, and a second exhaust port 7. The air inlet 5 is provided on a first side facing a duct provided in the stack case, and is supplied with the cooling air blown through the duct. The first exhaust port 6 is provided on a second side perpendicular to the first side, and exhausts the cooling air supplied from the air inlet 5. The second exhaust port 7 is provided on a third side perpendicular to the first side and opposite to the second side, and exhausts the cooling air supplied from the air inlet 5. In addition, in the first spacer 3, a flow path of the cooling air connecting the air inlet 5 and the first exhaust port 6 or the second exhaust port 7 is formed by a rib 8. In the first spacer 3, a first flow passage connecting the air supply port 5 and the first exhaust port 6 and a second flow passage connecting the air supply port 5 and the second exhaust port 7 are formed symmetrically.

[0014] Next, Fig. 3 is a diagram for explaining the flow path of the cooling air in the second spacer 4 according to the first embodiment. As shown in Fig. 3, the second spacer 4 also has an air inlet 5, a first exhaust port 6, and a second exhaust port 7, and the flow paths are formed by ribs 8. In the second spacer 4, the first flow path connecting the air inlet 5 and the first exhaust port 6 and the second flow path connecting the air inlet 5 and the second exhaust port 7 are formed asymmetrically.

[0015] Here, in the second spacer 4, it is preferable that the length of the first flow path is set shorter than the length of the second flow path. In addition, in the second spacer 4, the area of ​​the region in which the first flow path is formed is set to be the same as the area in which the second flow path is formed, and the area of ​​the rib constituting the first flow path is set smaller than the area of ​​the rib constituting the second flow path. By forming two asymmetrical flow paths like this, a difference is generated in the flow speed and air volume of the cooling air discharged from the first exhaust port 6 and the second exhaust port 7, and in the battery stack 1 according to the first embodiment, a drift is generated in the duct, and a vortex airflow in which the airflow swirls at the end of the duct in a direction perpendicular to the stacking direction or in a direction with a predetermined inclination can be generated. When such a vortex airflow is generated, an effect of increasing the wind pressure of the cooling air flowing from the duct to the second spacer 4 side is generated. The effect of this vortex airflow will be described in detail later.

[0016] Next, Fig. 4 shows a schematic diagram of the stack case 10 according to the first embodiment. Fig. 5 shows a schematic diagram of a duct portion of the stack case according to the first embodiment as viewed from the outside. The stack case 10 according to the first embodiment is configured to be able to store two battery stacks 1 side by side. Thus, Figs. 4 and 5 show a first battery stack 21 and a second battery stack 22 as the two battery stacks. Also, an air guide duct 18 is connected to the stack case 10.

[0017] In Fig. 4, the ducts provided in the stack case 10 include a first duct 14 corresponding to the first battery stack 21 and a second duct 15 corresponding to the second battery stack 22. In Fig. 4, in order to more clearly explain the duct structure, the stack case 10 is shown by a solid line, the first battery stack 21 and the second battery stack 22 are shown by dashed lines, and the lid and air guide duct 18 are not shown.

[0018] Also, in FIG. 5, only the spacer 31 incorporated in the first battery stack 21, the spacer 32 incorporated in the second battery stack 22, the first duct 14, and the second duct 15 are shown, and other members are omitted for ease of explanation.

[0019] First, in the secondary battery according to the first embodiment, as shown in FIG. 1, battery cells and spacers are alternately stacked to form a first battery stack 21 and a second battery stack 22. The first battery stack 21 and the second battery stack 22 are respectively stored in a battery stack storage area of ​​a stack case 10. The stack case 10 guides cooling air to a ventilation passage provided in the spacer via a first duct 14 and a second duct 15. At this time, in the secondary battery according to the first embodiment, one of the branched cooling airs obtained by dividing the cooling air supplied from one air outlet flows into the first duct 14, and the first duct 14 distributes the cooling air to the multiple spacers included in the first battery stack 21. In addition, in the secondary battery according to the first embodiment, the other branched cooling airs obtained by dividing the cooling air supplied from the air outlet flow into the second battery stack 22, and the second battery stack 22 distributes the cooling air to the multiple spacers included in the second battery stack 22.

[0020] As shown in Figs. 4 and 5, the stack case 10 houses a first battery stack 21 and a second battery stack 22 on the left and right sides with a partition wall 11 in between. The stack case 10 is fixed so that a left-right portion of the bottom of the first battery stack 21 and the second battery stack 22 contacts the battery contact surface 12. The stack case 10 has a first duct 14 formed on the bottom side of the first battery stack 21 and a second duct 15 formed on the bottom side of the second battery stack 22. The surfaces of the first duct 14 and the second duct 15 that contact the battery stacks are formed to be open, and the openings of the ducts are provided with air intakes for cooling air for the spacers 31 and 32 of the battery stacks. The first duct 14 and the second duct 15 distribute cooling air to the spacers 31 and 32.

[0021] The first duct 14 and the second duct 15 are supplied with cooling air from an air outlet provided in the air guide tube 18. At this time, the stack case 10 has a flow dividing structure 13 having a shape tapered toward the air intake port at a portion where the first duct 14 and the second duct 15 join. The cooling air supplied from the air intake port by this flow dividing structure 13 is divided into branched cooling air flowing to the first duct 14 side and branched cooling air flowing to the second duct 15. As will be described in detail later, near the entrance of each duct, the wind pressure and wind speed of the branched cooling air differ between the left and right in the width direction X inside the duct, so that a vortex air current swirling in a direction perpendicular to the stacking direction Y is generated.

[0022] As shown in Fig. 5, an air guide duct 18 is connected to the stack case 10, and cooling air is supplied from an air outlet provided in this air guide duct 18 to the first duct 14 and the second duct 15. One air outlet is provided for each of the two ducts. A blower for blowing cooling air may be provided in the air outlet.

[0023] Next, the flow of cooling air in the secondary battery according to the first embodiment will be described with reference to Fig. 6 and Fig. 7. Fig. 6 is a diagram explaining the flow of cooling air in ducts (e.g., first duct 14 and second duct 15) according to the first embodiment. Fig. 7 is a diagram explaining the flow of cooling air branched off from a duct to a spacer arranged between battery cells housed in the stack case according to the first embodiment.

[0024] In Fig. 6, the arrows showing the flow of the air current in the area where the wind pressure of the cooling air is high are thicker, and the arrows become thinner as the wind pressure decreases. In Fig. 7, more arrows are shown in the area where the wind pressure of the vortex air current is high, and the number of arrows becomes smaller as the wind pressure of the vortex air current decreases. Fig. 7 also shows a schematic diagram of the flow of the cooling air at three points in the stack storage area where the first battery stack 21 and the second battery stack 22 are stored. Specifically, Fig. 7 shows a schematic diagram of the flow of the cooling air at point A near the entrance of the duct in the stack storage area, point B near the center of the stack storage area, and point C near the end of the stack storage area.

[0025] 6, in stack case 10 according to the first embodiment, cooling air blown in from an air outlet is separated by airflow dividing structure 13 into branched cooling air that flows into first duct 14 and branched cooling air that flows into second duct 15. At this time, near airflow dividing structure 13, that is, near the inlets of each duct (for example, point A), the air pressure near the inside of stack case 10 is high and the air pressure near the outside is low.

[0026] Due to this difference in wind pressure, a strong vortex air current is generated as shown in Fig. 7. This vortex air current rotates clockwise on the first duct 14 side and counterclockwise on the second duct 15 side. Due to this vortex air current, the cooling air flowing toward the outside of the stack case 10 and the spacer 31 and the spacer 32 becomes greater than the cooling air flowing toward the inside.

[0027] Next, at point B, the wind pressure of the cooling air in the duct is lower than at point A, so the wind pressure difference between the left and right sides of the duct is also lower than at point A. As a result, the wind pressure of the vortex airflow is lower at point B than at point A. However, at point B, a vortex airflow is generated, so that as at point A, the cooling air flowing through spacers 31 and 32 becomes greater in the outward direction of stack case 10 than in the inward direction.

[0028] Next, at point C, by using the second spacer 4 instead of the first spacer 3, a difference occurs in the wind speed and volume of the cooling air flowing in the left-right direction of the battery stack via the second spacer 4. Due to this difference, a vortex airflow occurs even at the end of the duct in the stack case 10 according to the first embodiment. This vortex airflow allows the cooling air to flow smoothly in the spacer direction even at the end of the duct, thereby suppressing pressure loss at the end of the duct.

[0029] 7, the rib patterns of the second spacer 4 are set to be opposite (e.g., linearly symmetrical with respect to the direction in which the battery stacks are arranged) for the two battery stacks housed in the stack case 10. Specifically, in the second spacer 4, the first exhaust port is arranged on the side where the two battery stacks arranged side by side in the stack case 10 do not face each other, and the flow path length of the first flow path is set to be shorter than the flow path length of the second flow path.

[0030] Here, as a comparative example, the airflow when only the first spacer 3 is used as the spacer included in the battery stack will be described with reference to Figures 8 and 9. Figure 8 is a diagram explaining the flow of cooling air in a duct in the comparative example. Figure 9 is a diagram explaining the flow of cooling air branched from a duct to a spacer arranged between battery cells housed in a stack case in the comparative example.

[0031] As shown in Figs. 8 and 9, the duct according to the comparative example has almost the same airflow at points A and B as the duct according to the first embodiment. On the other hand, at point C, which is the end of the duct with or without a slope surface, the airflow is different between the comparative example and the first embodiment. Specifically, in the duct according to the comparative example, a vortex airflow is not generated at point C, but a vortex is generated in which the cooling air that reaches a dead end at the end swirls in a top view. In the comparative example, no vortex airflow is generated at point C, and the airflow flowing to the outside of the stack case through spacers 31 and 32 and the airflow flowing to the inside are almost the same in volume. The generation of the vortex airflow in the comparative example is due to a decrease in the wind pressure of the cooling air discharged through spacers 31 and 32, that is, the pressure loss is smaller than that of the duct according to the first embodiment.

[0032] From the above description, in the battery stack 1 according to the first embodiment, the pressure loss at the end of the duct is reduced, and the flow path pattern of the second spacer 4 located at the end is set asymmetrically in the left-right direction to provide a difference in the amount of cooling air discharged when viewed in the left-right direction of the duct. As a result, the battery stack 1 according to the first embodiment can generate a vortex airflow at the end of the duct to increase the efficiency of sending the cooling air to the spacers 31 and 32. In addition, in the secondary battery according to the first embodiment, it is possible to increase the cooling efficiency of the battery cells arranged near the end of the duct. Note that, by arranging the second spacer 4 in an area closer to the duct end than the half of the battery stack 1, the effect of reducing the pressure loss at the end of the duct is increased.

[0033] In the second spacer 4 according to the first embodiment, the length of the first flow path corresponding to one exhaust port (for example, the first exhaust port 6) is set shorter than the length of the second flow path corresponding to the other exhaust port (for example, the second exhaust port 7), so that the wind speed and the wind volume of the cooling air discharged from the first exhaust port 6 side can be made larger than those of the second exhaust port 7. In the second spacer 4 according to the first embodiment, the density of the ribs constituting the first flow path corresponding to one exhaust port (for example, the first exhaust port 6) is set lower than the density of the ribs constituting the second flow path corresponding to the other exhaust port (for example, the second exhaust port 7), so that the wind speed and the wind volume of the cooling air discharged from the first exhaust port 6 side can be made larger than those of the second exhaust port 7.

[0034] In the above embodiment, an example was described in which two ducts are provided for one air outlet to generate a vortex flow in the area near the duct inlet, but even if one duct is provided for one air outlet, a vortex flow can be generated near the duct inlet by tilting the airflow direction into the duct relative to the duct's direction of rotation. In other words, even if the battery stack configuration described above is used for a battery stack stored in a stack case in which one duct is provided for one air outlet, a vortex flow can be generated near the end of the duct to reduce pressure loss.

[0035] The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0036] 1 Battery stack 2 Battery Cells 3 First Spacer 4 Second Spacer 5 Air supply port 6 First exhaust port 7 Secondary exhaust vent 8. Ribs 10 Stack Case 11 Bulkhead 12 Battery contact surface 13 Diversion structure 14 First Duct 15 Second Duct 18 Wind guide 21 First battery stack 22 Second Battery Stack 31 Spacer 32 Spacer

Claims

1. A battery stack in which a plurality of battery cells and spacers are alternately stacked, The spacers each include an air inlet provided on a first side facing a duct provided in the stack case, the air inlet being for cooling air sent through the duct; a first exhaust port provided on a second side perpendicular to the first side and configured to exhaust the cooling air supplied from the air supply port; a second exhaust port provided on a third side perpendicular to the first side and facing the second side, the second exhaust port discharging the cooling air supplied from the air supply port; The spacers include a first spacer in which a first flow passage connecting the air inlet and the first exhaust port and a second flow passage connecting the air inlet and the second exhaust port are symmetrically formed; a second spacer in which a first flow passage connecting the air supply port and the first exhaust port and a second flow passage connecting the air supply port and the second exhaust port are asymmetrically formed, a plurality of the first spacers are arranged on a side of the battery stack near an air outlet that blows the cooling air into the duct; The battery stack includes a plurality of second spacers disposed on a duct end side opposite to the air outlet of the duct.

2. The battery stack according to claim 1 , wherein the second spacer is configured so that a flow path length of the first flow path is shorter than a flow path length of the second flow path.

3. 2. The battery stack according to claim 1, wherein the area of ​​the second spacer in which the first flow path is formed is set to be the same as the area in which the second flow path is formed, and the area of ​​a rib constituting the first flow path is set to be smaller than the area of ​​a rib constituting the second flow path.

4. The stack case includes: The two battery stacks are stored side by side, a first duct corresponding to one of the battery stacks; a second duct corresponding to the other battery stack; and a blower port for blowing the cooling air to the first duct and the second duct; The battery stack according to claim 1 ,

5. 5. The battery stack according to claim 4, wherein the first exhaust port of the second spacer is disposed on a side where the two battery stacks arranged side by side in the stack case do not face each other, and a flow path length of the first flow path is set shorter than a flow path length of the second flow path.

6. The battery stack according to claim 1 , wherein the second spacer is disposed in a region closer to the duct end than a half of the battery stack.

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