Battery pack

Abstract

To provide a battery pack that restrains the lamination direction center of a battery stack from being deformed to swell upward, in a state in which the battery stack is housed in a case in a restraining load-added state.SOLUTION: A support structure part 24, in which a case 20 having a housing space 27 for housing a battery stack 10 having end plates 13 and 14 arranged at both ends sandwiches the battery stack 10 between itself and an end wall 23, is provided. Additionally, a side plate 17, which is arranged between a second end plate 14 within the housing space 27 and the support structure part 24, is provided. The support structure part 24 has locking walls 31A and 31B that are erected on a bottom surface part 21. In the housing space 27, the battery stack 10 is restrained in a compressed state in a lamination direction. The locking walls 31A and 31B have a base end and a tip. A compressive reaction force applied to the locking walls 31A and 31B by the side plate is further exerted on the base end than on the tip.SELECTED DRAWING: Figure 3

Description

Technical Field

[0004] , , , , , ,

[0001] The present invention relates to a battery pack in which a battery stack formed by laminating battery cells is housed in a case.

Background Art

[0002] There is a battery pack configured as in Patent Document 1. Specifically, the battery stack includes a plurality of battery cells and end plates disposed at both ends in the stacking direction of the plurality of battery cells. The case has a rectangular box shape with an open upper surface. The battery stack constrained in the stacking direction is housed in the case from above in a suspended state. At this time, spacers are pre-disposed in the case so that an appropriate restraint load can be applied to the battery stack. Specifically, the case has side walls erected from around the bottom surface. And, the spacer is disposed inside one of the pair of opposing side walls in the stacking direction of the battery stack. When the battery stack is housed in the case, a restraint load is applied to the battery stack, while a compressive reaction force of the restraint load is applied to the pair of side walls in the stacking direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, the side walls are constructed by being erected integrally from the perimeter of the base. For this reason, the pair of side walls are more susceptible to deformation by the compressive reaction force of the constraining load at the tip, which is further from the base and has lower physical strength than the base. When a battery stack is housed, the pair of side walls in the stacking direction may deform into an upward-opening state with their tips facing outward due to the compressive reaction force from the battery stack. When the side walls deform into an upward-opening state, the battery stack housed in the case is more likely to deform so that its center in the stacking direction bulges upward. When the battery stack deforms to bulge upward, the degree of freedom in arranging components such as busbars on the top surface of the battery stack decreases. [Means for solving the problem]

[0005] A battery pack for solving the above problems comprises a battery stack comprising a plurality of battery cells and a first end plate and a second end plate arranged at each end of the plurality of battery cells in the stacking direction, and a case having a housing space for housing the battery stack, the case comprising a bottom surface located below the battery stack, an end wall located on the first end side of the battery cells in the stacking direction, and a support structure located on the second end side opposite to the first end of the battery cells in the stacking direction, which sandwiches the battery stack between the end wall and the case, and a side plate disposed between the second end plate located at the second end of the battery stack in the housing space and the support structure, wherein the support structure comprises a locking wall erected with respect to the bottom surface, the battery stack is constrained in a compressed state in the stacking direction within the housing space, the locking wall comprises a base end and a tip, and the compression reaction force from the side plate to the locking wall is applied more to the base end than to the tip.

[0006] The battery stack is housed in a compressed state within the housing space formed in the case. The locking wall has lower strength and is more prone to deformation at the tip than at the base, so the compressive reaction force on the locking wall by the side plate may cause the tip of the locking wall to deform outwards, opening upwards. If the locking wall deforms upwards, the battery stack may deform so that the center in the stacking direction bulges upwards. If the battery stack deforms to bulge upwards, the degree of freedom in arranging components such as busbars on the top surface of the battery stack is reduced.

[0007] In this regard, in the present invention, the locking wall is configured such that the compressive reaction force applied to the locking wall by the side plate is greater at the base end, which is less prone to deformation than at the tip. As a result, deformation in which the center of the battery stack bulges upward in the stacking direction is suppressed. Consequently, the placement of components such as busbars on the upper surface of the battery stack becomes easier.

[0008] In the above-described battery pack, it is preferable that the locking wall has a shape in which its tip is inclined toward the opposite side of the housing space from its base. With the above configuration, by making the locking wall so that its tip is inclined toward the opposite side of the housing space from its base, the compressive reaction force applied to the locking wall by the side plate can be configured to be greater toward the base than toward the tip of the locking wall. This makes it possible to suppress deformation in which the center of the battery stack in the stacking direction bulges upward.

[0009] In the above-described battery pack, the second end plate may be configured to include a partially inclined portion corresponding to the inclination of the locking wall in the portion that includes the lower end of the surface facing the side plate.

[0010] According to the above configuration, the side plate is tilted in accordance with the inclination of the partially inclined portion of the second end plate and is pressed against the locking wall in this tilted state. As a result, the side plate and the second end plate are separated at the tip. Consequently, the compressive reaction force from the side plate against the locking wall is largely applied to the base end of the locking wall through the side plate from the partially inclined portion. Therefore, the compressive reaction force from the side plate against the locking wall is applied more to the base end than to the tip, which suppresses deformation of the battery stack that causes the center in the stacking direction to bulge upward.

[0011] In the battery pack described above, the locking wall may be configured to have a base-side inclined portion that is inclined with a first inclination on the side opposite to the housing space, and a tip-side inclined portion that is closer to the tip than the base-side inclined portion and is inclined more than the first inclination, and the second end plate may be configured to have an inclined portion on the entire surface of the surface facing the side plate that corresponds to the inclination of the base-side inclined portion.

[0012] According to the above configuration, the side plate is pressed against the inclined portion on the base side of the locking wall in an inclined state that follows the inclination of the inclined portion of the second end plate. As a result, the locking wall and the side plate are separated at the inclined portion on the tip side. This causes the compressive reaction force from the side plate against the locking wall to be largely applied to the inclined portion on the base side of the locking wall through the side plate. Therefore, deformation in which the center of the battery stack in the stacking direction bulges upward and expands, caused by the compressive reaction force from the side plate against the locking wall being greater at the base than at the tip, can be suppressed.

[0013] In the above-described battery pack, the locking wall may be configured to have a projection on the surface facing the side plate that supports the side plate. With this configuration, the side plate that tends to tilt toward the locking wall is supported by the projection of the locking wall. This maintains a state in which the compressive reaction force from the side plate toward the locking wall is greater at the base than at the tip.

[0014] In the above-described battery pack, the locking walls are a pair, the pair of locking walls define an opening between them, a pressure plate is provided between the side plate and the second end plate, the side plate is a recess with an open end on its lower side, the recess is located in the opening, and the pressure plate may be configured such that a part of the pressure plate is exposed from the recess.

[0015] According to the above configuration, the battery pack is housed in the housing space with the battery stack and pressure plate unit positioned between a pair of locking walls. Subsequently, a pressure member presses the battery stack against the second end wall through the pressure plate. With the battery stack in a compressed state under pressure, a side plate is inserted between the second end plate and the pair of locking walls. At this time, the pressure member is avoided by the recess. As a result, the battery stack is constrained in a compressed state within the case. After being inserted between the second end plate and the pair of locking walls, the pressure plate functions as a reinforcing member that reinforces the second end plate. [Effects of the Invention]

[0016] According to the present invention, when a battery stack is housed in a case with a restraining load applied, it is possible to suppress deformation such that the center of the battery stack in the stacking direction bulges upward. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a perspective view of the battery pack. [Figure 2] Figure 2 is an exploded perspective view showing the relationship between the battery cell, second end plate, pressure plate, and side plate. [Figure 3] Figure 3 is a cross-sectional view of line 3-3 in Figure 4. [Figure 4] Figure 4 is a plan view of the main components of the battery pack, showing the relationship between the battery cells, the second end plate, the pressure plate, and the side plate. [Figure 5] Figure 5 is a side view of the battery pack. [Figure 6] FIG. 6 is a cross-sectional view of a main part conceptually showing a support structure of a battery cell, a second end plate, a pressing plate, a side plate, and a locking wall in a prerequisite battery pack. [Figure 7] FIG. 7 is a cross-sectional view of a main part conceptually showing a concept of a support structure of a battery cell, a second end plate, a pressing plate, a side plate, and a locking wall. [Figure 8] FIG. 8 is a cross-sectional view of a main part conceptually showing a support structure portion of a battery cell, a second end plate, a pressing plate, a side plate, and a locking wall in the battery pack shown in FIG. 1. [Figure 9] FIG. 9 is a perspective view of a main part showing a state where a load is applied to a battery stack by a pressing member. [Figure 10] FIG. 10 is a cross-sectional view of a main part conceptually showing a modified example of a support structure of a battery cell, a second end plate, a pressing plate, a side plate, and a locking wall. [Figure 11] FIG. 11 is a cross-sectional view of a main part conceptually showing a modified example of a support structure of a battery cell, a second end plate, a pressing plate, a side plate, and a locking wall.

DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, a battery pack to which the present invention is applied will be described with reference to the drawings. 〔Overall Configuration〕 As shown in FIG. 1, the battery pack 1 includes a battery stack 10 and a case 20. The battery stack 10 is housed in a compressed state in which a restraint load (compression load) is applied to the case 20.

[0019] The battery stack 10 comprises multiple rectangular battery cells 11. The multiple battery cells 11 in the battery stack 10 are stacked in the X direction. The X direction is the stacking direction of the battery cells 11. The multiple battery cells 11 are aligned in the width direction in the Y direction. Furthermore, the multiple battery cells 11 are aligned in the height direction in the Z direction. In addition, the battery pack 1 of this embodiment has the battery stacks 10 arranged in a row in the Y direction. The X and Y directions are horizontal directions, and the Z direction is vertical direction. Here, the battery stacks 10 are arranged in two rows in the Y direction, but the number of battery stacks 10 may be one row or three or more rows.

[0020] The case 20 is formed in a rectangular box shape. It comprises a bottom surface 21 located below the battery stack 10, a pair of side walls 22, an end wall 23, and a support structure 24. The pair of side walls 22, the end wall 23, and the support structure 24 extend upward integrally with the bottom surface 21, forming an upper opening 25. The pair of side walls 22 are walls that extend in the X direction parallel to each other. The end wall 23 is a wall that extends in the Y direction at the back in the X direction.

[0021] The case 20 is provided with a partition wall 26 parallel to the side walls 22 between a pair of side walls 22. Between one side wall 22 and the partition wall 26, and between the other side wall 22 and the partition wall 26, there is a housing space 27 for housing the battery stack 10. The housing space 27 houses the battery cells 11 of the battery stack 10 in an aligned stacking direction. The support structure 24 is located on the opposite side of the end wall 23 and is provided with an opening 28 that is continuous with the top opening 25, corresponding to each housing space 27. The support structure 24 is provided with a pair of locking walls 31A and 31B, corresponding to each opening 28. Each opening 28 is demarcated by the pair of locking walls 31A and 31B. One of the pair of locking walls, 31A, is connected to the end of the side wall 22, and the other locking wall 31B is connected to the end of the partition wall 26. The case 20 configured in this way has sufficient strength to withstand the compressive reaction force S while appropriately compressing the battery stack 10. The compressive reaction force S is the reaction force to the restraining load (compressive load) in the direction that causes the first end plate 13 and the second end plate 14 of the battery stack 10 to move away from each other, that is, in the direction that expands in the stacking direction.

[0022] In each storage space 27, the battery stack 10 is inserted through the opening 28, with its first end (the end in the stacking direction) being the insertion end, sliding parallel to the bottom surface 21. Subsequently, the battery stack 10 is inserted between its second end (opposite the first end) and a pair of locking walls 31A and 31B, with the side plates 17 secured to the pair of locking walls 31A and 31B. As the side plates 17 are locked to the pair of locking walls 31A and 31B, the battery stack 10 is housed in each storage space 27 in a compressed state with a restraining load applied.

[0023] [Battery stack] As shown in Figure 2, the battery stack 10 comprises a plurality of battery cells 11, a spacer 12, a first end plate 13, and a second end plate 14.

[0024] Multiple battery cells 11 are stacked in the X direction. Spacers 12 are interposed between adjacent battery cells 11. Each battery cell 11 is, for example, a non-aqueous secondary battery, and one example is a lithium-ion secondary battery. Each battery cell 11 comprises a battery case and a lid. The battery case and lid are made of a metal such as aluminum or an aluminum alloy. The battery case houses a wound body, which is constructed by winding a laminate of a positive electrode sheet, a negative electrode sheet, and a separator, together with a non-aqueous electrolyte, and is then sealed with a lid. Each battery cell 11 has a flat, bottomed rectangular (cuboidal) outer shape. The lid is provided with an external terminal 11A for the positive electrode and an external terminal 11B for the negative electrode. The external terminals 11A and 11B are used for charging and discharging power.

[0025] The positive terminal 11A and the negative terminal 11B of adjacent battery cells 11 are electrically connected by a busbar 15. The busbar 15 is, for example, a conductive metal plate with an elongated shape. Adjacent battery cells 11 are electrically connected in series by the busbar 15.

[0026] Spacers 12 are placed one at a time between adjacent battery cells 11. Each surface of the spacer 12 has a recess 12A into which the side surface of the battery cell 11 is fitted. The recess 12A is made up of ribs that serve as heat dissipation passages, etc. The first end plate 13 is placed at the first end of the battery stack 10. The first end plate 13 is pressed against the end wall 23 by the compressive reaction force S of the restraining load (see Figure 1). The second end plate 14 is placed at the second end of the battery stack 10.

[0027] The spacer 12, the first end plate 13, and the second end plate 14 are made of an insulating material, such as a molded synthetic resin. Furthermore, the spacer 12, the first end plate 13, and the second end plate 14 are preferably made of a material with high thermal conductivity in order to improve the heat dissipation of the battery cell 11.

[0028] As shown in Figure 3, the battery stack 10 has spacers 12 interposed between multiple battery cells 11, with a first end plate 13 positioned at the first end and a second end plate 14 positioned at the second end. Furthermore, a pressure plate 16 is placed on top of the second end plate 14 to form a single unit. This unit is inserted into each housing space 27 through each opening 28, with the first end plate 13 as the insertion end. Each opening 28 is sized to accommodate this unit.

[0029] The pressure plate 16 is a plate that is directly pressed against the pressure member 32 and is a metal plate with high physical strength to protect the second end plate 14. The pressure plate 16 is preferably made of a material with high thermal conductivity. The pressure plate 16 is a rectangular plate configured to be the same size as the plate portion 17A. After being housed in the case 20, the pressure plate 16 also functions as a protective plate to protect the second end plate 14.

[0030] [Side Plate] A side plate 17 is positioned between the pressure plate 16 and the support structure 24. The pressure plate 16 and the side plate 17 are metal plates such as aluminum. The side plate 17 comprises a plate portion 17A, an engaging piece 17B, and a recess 17C. The plate portion 17A is made of a rectangular plate. The size of the plate portion 17A is larger than the opening 28 and is large enough to be locked into the pair of locking walls 31A and 31B that constitute the opening 28. The plate portion 17A also has a recess 17C which has a recessed shape with its lower end as an open end. The recess 17C is a relief portion for the pressure member 32 that presses the battery stack 10 toward the end wall 23. While the pressure member 32 is pressing the battery stack 10 toward the end wall 23 through the pressure plate 16, the plate portion 17A of the side plate 17 is inserted into the gap between the pair of locking walls 31A and 31B and the pressure plate 16. The pressure member 32 is located in the recess 17C. The engaging piece 17B is a piece bent at approximately a right angle to the plate portion 17A. When the plate portion 17A is inserted into the gap between the pair of locking walls 31A, 31B and the pressure plate 16, it is locked to the ends of the pair of locking walls 31A, 31B.

[0031] For example, several types of side plates 17 are available with different thicknesses of the plate portion 17A. The case 20 has variations in the internal dimensions between the base end of the support structure 24 and the base end of the end wall 23 due to manufacturing tolerances. A side plate 17 with a thickness that can absorb these variations due to manufacturing tolerances and apply a predetermined restraining load to the battery stack 10 is selected. The selected side plate 17 is then inserted into the gap between the pair of locking walls 31A, 31B and the pressure plate 16. As an example, grooves are formed in the bottom surface portion 21 on the housing space 27 side, which is the base end of the pair of locking walls 31A, 31B, and the insertion end, which is the tip of the plate portion 17A, engages with the grooves.

[0032] The internal dimension between the base end of the support structure 24 and the base end of the end wall 23 is set so that a predetermined restraining load is applied to the battery stack 10 when the side plate 17 is inserted into the gap between the pair of locking walls 31A, 31B and the pressure plate 16. For example, the internal dimension is smaller than the combined stacking dimension of the battery stack 10 and the pressure plate 16 when no restraining load is applied. The internal dimension is larger than the combined stacking dimension of the battery stack 10 and the pressure plate 16 when pressed against the end wall 23 by the pressure member 32. Furthermore, the internal dimension is set so that when the side plate 17 is inserted and the pressure is released by the pressure member 32, the first end plate 13 is pressed against the end wall 23 and the side plate 17 is pressed against the base ends of the pair of locking walls 31A, 31B.

[0033] 〔case〕 As described above, the case 20 is formed in a rectangular box shape by die-casting aluminum. It comprises a bottom surface 21 located below the battery stack 10, a pair of side walls 22, an end wall 23, and a support structure 24. For example, the pair of side walls 22 and the end wall 23 are erected perpendicular to the bottom surface 21. Since the case 20 is made of die-cast aluminum, the pair of side walls 22 and the end wall 23 may also have a slightly upward-opening shape in order to remove the top mold. The pair of locking walls 31A and 31B that constitute the support structure 24 are also configured to be inclined toward the opposite side of the housing space 27, i.e., upward-opening. For example, the inclination of the pair of locking walls 31A and 31B is greater than the inclination of the pair of side walls 22 and the end wall 23, even if they are inclined.

[0034] As shown in Figures 4 and 5, the support structure 24 is provided with a pair of locking walls 31A and 31B for partitioning the openings 28 of each accommodation space 27. In one accommodation space 27, the support structure 24 is provided with a first locking wall 31A formed by bending one end of one side wall 22 toward the partition wall 26 in the Y direction (inward). Furthermore, it is provided with a second locking wall 31B formed by bending the end of the partition wall 26 toward the direction of one side wall 22 in the Y direction (inward). In the other accommodation space 27, the support structure 24 is provided with a first locking wall 31A formed by bending the other end of the side wall 22 toward the partition wall 26 in the Y direction (inward). Furthermore, it is provided with a second locking wall 31B formed by bending the end of the partition wall 26 toward the direction of the other side wall 22 in the Y direction (inward). In other words, the second locking walls 31B are provided in both directions from the end of the partition wall 26. The outer periphery of the plate portion 17A of the side plate 17 faces the inner surfaces of the pair of locking walls 31A and 31B.

[0035] The pair of locking walls 31A and 31B are subjected to a compressive reaction force S of the restraining load via the side plates 17. The pair of locking walls 31A and 31B are configured to have an upward-opening shape, so that the compressive reaction force S applied to the pair of locking walls 31A and 31B by the side plates 17 is greater towards the base end than towards the tip end.

[0036] As shown in Figure 6, when the pair of locking walls 31A and 31B are perpendicular to the bottom surface 21, the compressive reaction force S applied by the side plate 17 to the pair of locking walls 31A and 31B is applied to the pair of locking walls 31A and 31B. The physical strength of the pair of locking walls 31A and 31B is lower and they are more easily deformed towards the tip than towards the base end closer to the bottom surface 21. Therefore, when the compressive reaction force S applied by the side plate 17 to the pair of locking walls 31A and 31B, the pair of locking walls 31A and 31B deform into an upward-opening state. As a result, the battery stack 10 deforms so that the center in the stacking direction bulges upward due to the compressive reaction force S of the restraining load. In such a case, it becomes difficult to arrange components such as the busbar 15 that are placed on the top surface of the battery stack 10.

[0037] Therefore, as shown in Figure 7, a pair of locking walls 31A and 31B are formed in an upward-opening state in advance, and the compression reaction force S applied to the pair of locking walls 31A and 31B by the side plate 17 is set to be larger on the base end side than on the tip end side. In this case, the compression reaction force S applied to the pair of locking walls 31A and 31B by the side plate 17 is smaller on the tip end side than on the base end side. The base end of the pair of locking walls 31A and 31B has higher physical strength and is less prone to deformation than the tip end side. Therefore, the expansion of the battery stack 10 in the stacking direction can be suppressed by the end wall 23 and the pair of locking walls 31A and 31B. At the same time, deformation in which the center of the battery stack 10 bulges upward can be suppressed.

[0038] However, in the example shown in Figure 7, the side plate 17 is only supported by being sandwiched between the second end plate 14 and the base ends of the pair of locking walls 31A and 31B. As a result, the position of the side plate 17 is unstable and it is prone to tipping over in the direction of the pair of locking walls 31A and 31B.

[0039] In the example shown in Figure 8, the second end plate 14 has a partial inclined portion 14A on the surface facing the pressure plate 16, including the lower end, which is composed of an inclined surface corresponding to the inclined surfaces of the pair of locking walls 31A and 31B. That is, the inclination of the inclined surface constituting the partial inclined portion 14A is the same as the inclination of the inclined surfaces of the pair of locking walls 31A and 31B shown in Figures 7 and 8, and is, for example, parallel. Furthermore, the partial inclined portion 14A of the second end plate 14 is located below the center of the height dimension in the Z direction on the surface facing the pressure plate 16. As a result, the pressure plate 16 makes surface contact with the partial inclined portion 14A. The side plate 17 also inclins in accordance with the partial inclined portion 14A. Consequently, the upper end of the second end plate 14 and the upper ends of the pressure plate 16 and the side plate 17 are separated, forming a gap 29.

[0040] As a result, even though the side plate 17 is supported by the pair of locking walls 31A and 31B, the force exerted by the side plate 17 on the pair of locking walls 31A and 31B due to the compressive reaction force S is greater at the base end than at the tip end. This suppresses deformation in the battery stack 10, where the center in the stacking direction bulges upward. As a result, the degree of freedom in arranging components such as the busbar 15 placed on the upper surface of the battery stack 10 is improved.

[0041] [Assembly method] The battery stack 10 has spacers 12 interposed between multiple battery cells 11, with a first end plate 13 positioned at the first end and a second end plate 14 positioned at the second end. Furthermore, a pressure plate 16 is placed on top of the second end plate 14 to form a single unit. This unit is inserted into each housing space 27 through each opening 28, with the first end plate 13 as the insertion end.

[0042] As shown in Figure 9, the pressurizing member 32 enters through the opening 28 and presses a predetermined position, such as the center of the pressurizing plate 16, with a predetermined pressure. As a result, the battery stack 10 is compressed by a restraining load between the pressurizing plate 16 and the end wall 23. When the battery stack 10 is compressed, the side plate 17 is inserted into the gap between the pair of locking walls 31A, 31B and the pressurizing plate 16. The pressurizing member 32 can escape through the recess 17C. A part of the pressurizing plate 16 is exposed through the recess 17C. After the insertion of the side plate 17, the pressurizing member 32 is released. As a result, the dimensions of the battery stack 10 in the stacking direction increase, and a predetermined restraining load is applied by the end wall 23 and the base ends of the pair of locking walls 31A, 31B. The battery stack 10, to which a restraining load is applied, is firmly held between the end wall 23 and the base ends of the pair of locking walls 31A and 31B, so that each battery cell 11 and spacer 12 is perpendicular to the bottom surface 21.

[0043] On the other hand, the lower end of the side plate 17 presses against the lower portion including the lower ends of the pair of locking walls 31A and 31B by the compressive reaction force S against the pair of locking walls 31A and 31B. The pressure plate 16 and the side plate 17 are pressed against the side surface of the battery cell 11 and tilt to follow the partially inclined portion 14A of the upright second end plate 14. Then, the upper ends of the second end plate 14 and the upper end of the second end plate 14 are separated, forming a gap 29. As a result, the compressive reaction force S from the side plate 17 against the pair of locking walls 31A and 31B is smaller at the tip side than at the base side. This suppresses deformation of the battery stack 10 such that the center in the stacking direction bulges upward. After this, components such as busbars 15 are placed on the upper surface of the battery stack 10.

[0044] [Effects of the Embodiment] The battery pack 1 described above can achieve the following effects: (1-1) The compressive reaction force S applied by the side plate 17 to the pair of locking walls 31A and 31B is greater towards the base than towards the tip. The battery stack 10, with the restraining load applied, is firmly held between the end wall 23 and the base sides of the pair of locking walls 31A and 31B. Accordingly, deformation of the battery stack 10, such as the center of the stacking direction bulging upward, is suppressed. As a result, the placement of components such as the busbar 15 on the upper surface of the battery stack 10 becomes easier.

[0045] (1-2) The pair of locking walls 31A and 31B are pre-shaped so that their tips are inclined toward the opposite side of the housing space 27 from their bases. This allows the compressive reaction force S applied by the side plate 17 to the pair of locking walls 31A and 31B to be greater at the bases than at the tips. This suppresses deformation in which the center of the battery stack 10 bulges upward in the stacking direction.

[0046] (1-3) The side plate 17 is pressed against the pair of locking walls 31A and 31B in an inclined state that follows the inclination of the partially inclined portion 14A of the second end plate 14. As a result, the side plate 17 and the second end plate 14 separate at the tip side, forming a gap 29. Thus, the compressive reaction force S from the side plate 17 against the pair of locking walls 31A and 31B is applied from the partially inclined portion 14A through the side plate 17 to the base end side of the pair of locking walls 31A and 31B. Therefore, the compressive reaction force S from the side plate 17 against the pair of locking walls 31A and 31B is applied more to the base end side than to the tip side. As a result, deformation of the battery stack 10, in which the center in the stacking direction bulges upward, can be suppressed.

[0047] (1-4) The battery pack 1 consists of a battery stack 10 and a pressure plate 16, which are housed in the housing space 27 between a pair of locking walls 31A and 31B. Then, the pressure member 32 presses the battery stack 10 against the end wall 23 through the pressure plate 16. With the battery stack 10 in a compressed state under pressure, the side plate 17 is inserted into the gap between the second end plate 14 and the pair of locking walls 31A and 31B. At this time, the pressure member 32 is avoided by the recess 12A. As a result, the battery stack 10 is restrained in a compressed state within the case 20.

[0048] (1-5) The pressure plate 16 has higher strength than the second end plate 14 and functions as a reinforcing member that reinforces the second end plate 14 after insertion. In other words, the pressure plate 16 can suppress the brittleness of the second end plate 14 by directly pressing the second end plate 14 with the pressure member 32.

[0049] Furthermore, battery pack 1 can be modified as needed, as follows. The configuration in which the compressive reaction force S applied by the side plate 17 to the pair of locking walls 31A and 31B is greater towards the base than towards the tip may be as shown in Figure 10. That is, the pair of locking walls 31A and 31B are composed of a base-side inclined portion 36 that is inclined with a first inclination relative to the bottom surface 21 on the opposite side from the housing space 27, and a tip-side inclined portion 37 that is closer to the tip than the base-side inclined portion 36 and is inclined more than the first inclination. The second end plate 14 is provided with a full-surface inclined portion 38 on the entire surface of the surface facing the side plate 17, corresponding to the inclination of the base-side inclined portion 36. For example, the base-side inclined portion 36 and the full-surface inclined portion 38 are parallel. The tip-side inclined portion 37 is not the surface that the side plate 17 contacts, so it may be an arc-shaped surface that bulges outward or is concave. Also, the tip-side inclined portion 37 may have an inclination such that a smaller compressive reaction force S is applied than that of the base-side inclined portion 36.

[0050] With this configuration, the side plate 17 is pressed against the base-side inclined portion 36 of the pair of locking walls 31A and 31B in an inclined state that follows the inclination of the entire inclined portion 38 of the second end plate 14. As a result, the pair of locking walls 31A and 31B and the side plate 17 are separated at the tip-side inclined portion 37, forming a gap 35. This allows the compressive reaction force S from the side plate 17 against the pair of locking walls 31A and 31B to be significantly applied to the base-side inclined portion 36 of the pair of locking walls 31A and 31B through the side plate 17. The battery stack 10, with the restraining load applied, is firmly held between the end wall 23 and the base-side inclined portion 36. Accordingly, deformation of the battery stack 10, such that the center in the stacking direction bulges upward, can be suppressed.

[0051] Furthermore, the entire inclined portion 38 may be a partial inclined portion provided in the lower region including the lower end, such as the lower half of the surface of the second end plate 14 facing the side plate 17. This configuration allows the pressure plate 16 and the side plate 17 to be inclined to follow the base end inclined portion 36.

[0052] The configuration in which the compressive reaction force S on the pair of locking walls 31A and 31B by the side plate 17 is greater at the base than at the tip may be as shown in Figure 11. The pair of locking walls 31A and 31B are provided with projections 39 on the surface facing the side plate 17 to support the side plate 17. There may be one projection 39 on each locking wall as shown in Figure 11, or there may be multiple projections in the vertical direction. A gap 40 is formed between the side plate 17 and the pair of locking walls 31A and 31B.

[0053] With this configuration, the side plate 17, which tends to tilt in the direction of the pair of locking walls 31A and 31B, is supported by the protrusions 39 of the pair of locking walls 31A and 31B. As a result, the compressive reaction force S applied by the side plate 17 to the pair of locking walls 31A and 31B is maintained to be greater at the base than at the tip, thereby suppressing deformation in which the center of the battery stack 10 bulges upward in the stacking direction.

[0054] • In the battery pack 1, the pressure plate 16 may be omitted. In this case, the second end plate 14 will be directly pressed by the pressure member 32, so it is preferable to construct it from a material or structure with higher physical strength.

[0055] The battery stack 10 may be inserted into the storage space 27 by sliding it parallel to the bottom surface 21 through the opening 28, or it may be inserted in a restrained state through the top opening 25 of the case 20. In this case, the support structure 24 does not have to consist of a pair of locking walls 31A, 31B spaced apart from each other to partition the opening 28. In this case, for example, the locking walls constituting the support structure may consist of walls that constitute a single side wall section that omits the opening 28.

[0056] As a modification of Figure 8, the locking wall may be erected perpendicular to the bottom surface 21, and the inner surface on the side of the storage space 27 may be configured as an inclined surface that slopes toward the opposite side of the storage space 27 from the base end toward the tip. That is, the locking wall may be configured with a vertical outer surface and an inclined inner surface as described above, with the plate thickness decreasing from the base end toward the tip. With such a configuration, the compressive reaction force S applied to the locking wall by the side plate 17 can be configured to be greater at the base end than at the tip.

[0057] The battery cell 11 is not limited to lithium-ion secondary batteries, but may be a nickel-metal hydride secondary battery or the like, as long as it has a configuration comprising a positive electrode sheet, a negative electrode sheet, and a non-aqueous electrolyte. The battery pack 1 may be installed in automated guided vehicles, special cargo handling vehicles, electric vehicles, hybrid vehicles, etc., as well as in computers and other electronic devices, or it may constitute a system other than those mentioned above. For example, it may be installed in mobile bodies such as ships and aircraft, or it may be part of a power supply system that supplies electricity from a power plant to buildings and homes where secondary batteries are installed via substations, etc. [Explanation of symbols]

[0058] S...Compression reaction force 1…Battery pack 10...Battery stack 11…Battery cell 11A,11B…External terminal 12…Spacer 12A…recess 13…First end plate 14…Second end plate 14A…partial slope part 15…Bus bar 16…Pressure plate 17... Side Plate 17A…Plate part 17B…Engagement piece 17C…recess 20...cases 21…Bottom part 22... Sidewall 23… End Wall 24...Support structure part 25…Top opening 26... Partition wall 27…Containment space 28…Aperture 29, 35, 40... gaps 31A…1st locking wall 31B…Second locking wall 32…Pressurizing member 36…Proximal inclined part 37…Tip side inclined part 38…Full slope part 39… protrusion

Claims

1. A battery stack comprising a plurality of battery cells, and a first end plate and a second end plate positioned at each end of the plurality of battery cells in the stacking direction, A case having a housing space for housing the battery stack, comprising: a bottom portion located below the battery stack; an end wall located on the first end side of the battery cell in the stacking direction; and a support structure located on the second end side opposite to the first end of the battery cell in the stacking direction, which sandwiches the battery stack between the end wall and the case. The system comprises a side plate positioned between the second end plate located at the second end of the battery stack within the housing space and the support structure, The support structure includes a locking wall erected against the bottom surface, The battery stack is constrained in a compressed state in the stacking direction within the housing space. The locking wall comprises a base end and a tip end, and the tip end on the inner surface facing the accommodating space is shaped to be inclined more toward the opposite side of the accommodating space than the base end, and the compression reaction force applied to the locking wall by the side plate is greater toward the base end than toward the tip end, A gap is provided between the side plate and the tip of the locking wall, making the tip of the locking wall less prone to deformation. Battery pack.

2. The second end plate includes a portion of the lower end of the surface facing the side plate that corresponds to the inclination of the locking wall. The battery pack according to claim 1.

3. The locking wall comprises a base-side inclined portion that is inclined with a first inclination on the side opposite to the accommodation space, and a tip-side inclined portion that is closer to the tip than the base-side inclined portion and is inclined more than the first inclination. The second end plate has an inclined portion on the entire surface of the surface facing the side plate that corresponds to the inclination of the base end inclined portion. The battery pack according to claim 1.

4. The battery pack according to claim 1, wherein the locking wall has a projection on the surface facing the side plate that supports the side plate.

5. The aforementioned locking walls are a pair, and the pair of locking walls partition an opening between them. A pressure plate is provided between the side plate and the second end plate. The side plate has a recess with an open end on the lower side, and comprises the recess located at the opening, The pressure plate has a portion of it exposed from the recess. A battery pack according to any one of claims 1 to 4.

Images