Battery-pack pressurization device and battery pack comprising same

Abstract

Provided is a battery-pack pressurization device capable of increasing cell capacity by reducing mechanical volume. A pressurization device (30) is used in a battery pack (1) provided with a battery module (10) in which a plurality of battery cells (12) are stacked, and the pressurization device pressurizes the plurality of battery cells (12) in an expansion / contraction direction (M). The pressurization device (30) comprises: a cell-side pressure plate (31) and a driving-side pressure plate (32) that are arranged to face each other in the expansion / contraction direction (M) with respect to the battery module (10); a uniform surface-pressure distribution mechanism (50) provided between the pair of pressure plates (31, 32) and capable of distributing a pressing force on the battery module (10); a linear motion mechanism (40) that uses a feed screw capable of moving, along the expansion / contraction direction (M), the distance between the pair of pressure plates (31, 32); and a drive mechanism (60) that is disposed on the opposite side of the uniform surface-pressure distribution mechanism (50) relative to the driving-side pressure plate (32) and that drives the linear motion mechanism (40).

Description

Battery pack pressure device and battery pack equipped with the same

[0001] The present invention relates to a battery pack including a battery module in which multiple battery cells are stacked, and more particularly to a battery pack pressure device that applies pressure to multiple battery cells of this type of battery module in the stacked expansion / contraction direction, and a battery pack including the same.

[0002] In a battery module that uses all-solid-state batteries as battery cells, the multiple battery cells expand and contract in the stacked direction in response to charge and discharge. Therefore, to ensure proper performance, it is necessary to maintain a uniform pressure of at least a predetermined level regardless of the charge and discharge state. As one measure to achieve this, for example, Patent Document 1 discloses a pressure structure that applies pressure to the battery module from both ends of the stacked direction of the multiple battery cells using a linear motion mechanism that uses a feed screw and a spring member.

[0003] Japanese Patent Application Laid-Open No. 2021-190161

[0004] However, in the pressure structure described in Patent Document 1, the linear motion mechanism and spring member are respectively disposed at both ends of the battery module. This reduces the cell capacity that can be achieved by stacking multiple battery cells. Furthermore, in the technology described in Patent Document 1, the spring member of the pressure structure is disposed only at the center of the battery cells in the stacking direction. This also creates the problem of uneven distribution of the surface pressure that presses the battery module.

[0005] Therefore, the present invention has been made in consideration of these problems, and it is an object of the present invention to provide a pressure device for a battery pack that can reduce the volume occupied by the pressure structure within the battery pack and increase the cell capacity that can be achieved by stacking battery cells, and a battery pack equipped with the same.

[0006] In order to solve the above problems, one aspect of the present invention provides a pressure device for a battery pack, which is used in a battery pack including a battery module in which a plurality of battery cells are stacked, and which presses the plurality of battery cells in the expansion / contraction direction of the stacked battery cells, and which includes a cell-side pressure plate and a drive-side pressure plate which are arranged opposite the battery module in the expansion / contraction direction, a surface pressure distribution uniformity mechanism which is provided between the cell-side pressure plate and the drive-side pressure plate and is capable of distributing the pressing force against the battery module, a linear motion mechanism which uses a feed screw which is movable along the expansion / contraction direction by a distance between the cell-side pressure plate and the drive-side pressure plate, and a drive mechanism which is arranged on the opposite side of the drive-side pressure plate from the surface pressure distribution uniformity mechanism and drives the linear motion mechanism.

[0007] In addition, in order to solve the above problem, a battery pack according to one aspect of the present invention is a battery pack including a battery module in which a plurality of battery cells are stacked, and a pressure device that pressurizes the plurality of battery cells in the direction of expansion and contraction of the stacked battery cells, and the pressure device includes a pressure device for a battery pack according to one aspect of the present invention.

[0008] According to the present invention, the volume occupied by the pressurizing structure in the battery pack can be reduced, thereby increasing the cell capacity.

[0009] 1 is a schematic explanatory diagram of a first embodiment of a battery pack including a pressure device according to an aspect of the present invention. FIG. 1 is an explanatory diagram showing the pressure device of FIG. 2. FIG. 2 is an explanatory diagram of a surface pressure distribution uniformity mechanism included in the pressure device of FIG. 2, where FIG. 1(a) is a schematic plan view of FIG. 2 and FIG. 1(b) is a diagram showing an image of the surface pressure distribution uniformity function. FIG. 2 is a schematic explanatory diagram of a second embodiment of a battery pack including a pressure device according to an aspect of the present invention. FIG. 3 is a graph showing an image of desired control of surface pressure on a battery module by the pressure devices of the first and second embodiments. FIG. 4 is a schematic diagram showing a modified example of the surface pressure distribution uniformity mechanism in the pressure devices of the first and second embodiments. FIG. 5 is a schematic diagram showing another modified example of the surface pressure distribution uniformity mechanism in the pressure devices of the first and second embodiments. FIG. 6 is an explanatory diagram of the operation of a drive mechanism included in the pressure devices of the first and second embodiments, where FIG. 6(a) shows an image of the worm wheel smoothly rotating in response to the driving force on the worm side, and FIG. 6(b) shows an image of the worm not rotating from the worm wheel side due to self-locking. FIG. 10 is a schematic perspective view showing a modified example of the linear motion mechanism and the drive mechanism in the pressure device of the first and second embodiments.

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. Note that the drawings are schematic. Therefore, it should be noted that the relationship between thickness and planar dimensions, ratios, etc., differ from the actual ones, and the dimensional relationships and ratios between the drawings also differ. Furthermore, the embodiments shown below are merely examples of devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention does not limit the materials, shapes, structures, arrangements, etc. of component parts to the following embodiments.

[0011] [Configuration of Battery Pack (First Embodiment)] First, a first embodiment of a battery pack will be described. As shown in Fig. 1 , the battery pack 1 of the first embodiment includes one battery module 10. The battery module 10 is configured by stacking a plurality of battery cells 12 in an expansion / contraction direction M.

[0012] Each battery cell 12 constituting the battery module 10 is a Li deposition type all-solid-state battery, and expands and contracts in the stacking direction of the battery cells 12 in response to charging and discharging. Compared to conventional liquid Lib type batteries, Li deposition type all-solid-state batteries use Li metal in the negative electrode, resulting in a significantly larger amount of cell expansion.

[0013] The battery pack 1 of the first embodiment includes a storage case 20 that houses the battery module 10, and a pressure device 30 that pressurizes the battery module 10 in the expansion / contraction direction M of the multiple battery cells 12. The storage case 20 is, for example, a rectangular parallelepiped housing made of metal (for example, aluminum alloy), and stores the multiple battery cells 12 in a stacked position along the long side of the storage case 20.

[0014] The pressure applying device 30 of the first embodiment is disposed between one end face (the lower end in the figure) of the battery module 10 and the short side of the housing case 20 that faces the end face. This maintains the stacked arrangement of the battery modules 10 inside the housing case 20, with the multiple battery cells 12 constantly being pressed upward in the expansion / contraction direction M by the pressure applying device 30 at the bottom in the figure.

[0015] [Configuration of Pressure Apparatus] Next, the pressure apparatus 30 will be described in more detail. As shown in Fig. 2 , which is an enlarged view of a main portion, the pressure apparatus 30 of this embodiment includes a cell-side pressure plate 32 and a drive-side pressure plate 31 that are arranged to face the battery module 10 in the expansion / contraction direction M, a linear motion mechanism 40 that changes the facing distance between the cell-side pressure plate 32 and the drive-side pressure plate 31 along the expansion / contraction direction M, and a drive mechanism 60 that drives the linear motion mechanism 40. The cell-side pressure plate 32 is able to abut against battery cells 12 at opposite ends in the expansion / contraction direction M and press the entire battery module 10. The drive-side pressure plate 31 is configured to be able to advance and retreat in the expansion / contraction direction M in response to drive of the drive mechanism 60, as will be described later.

[0016] The drive mechanism 60 is disposed on the opposite side of the drive-side pressure plate 31 from the surface pressure distribution uniforming mechanism 50. In this embodiment, the thickness of the cell-side pressure plate 32 and the drive-side pressure plate 31 are different from each other. In the example shown in the figure, the thickness of the cell-side pressure plate 32 is thinner than the thickness of the drive-side pressure plate 31. The thickness of the cell-side pressure plate 32 and the thickness of the drive-side pressure plate 31 may be the same. In the drive mechanism 60 of this embodiment, a motor 63 is fixed to the inner wall surface of the storage case 20 via a drive unit holder 70 (see FIG. 1). A worm gear is used for the drive mechanism 60. The worm gear is a rotation mechanism that combines a worm (screw gear) 61 and a worm wheel (helical teeth) 62 that meshes with the worm. The worm gear is not limited to a worm gear, and a hypoid gear, for example, may also be used.

[0017] The worm 61 is provided coaxially on the tip of the output shaft of the motor 63, and when the worm 61 is rotated by the drive of the motor 63, the teeth of the worm wheel 62 are advanced in the circumferential direction, thereby rotating the worm wheel 62. In this embodiment, the lead angle of the worm 61 is made small and set to be self-locking, preventing transmission of rotation from the worm wheel 62 side to the worm 61 side.

[0018] In this embodiment, a ball screw using, for example, a feed screw is employed as the linear motion mechanism 40. The ball screw includes a nut 42 having a helical thread groove formed on its inner peripheral surface, a screw shaft 41 having a helical thread groove formed on its outer peripheral surface that faces the thread groove of the nut 42, and a large number of balls (not shown) interposed in ball rolling paths formed between the facing thread grooves of the screw shaft 41 and the nut 42.

[0019] The numerous balls are housed inside in a ball circulation mechanism (not shown) that includes a ball circulation path, etc., so as to be able to circulate infinitely. The member screw shaft 41 penetrates the drive-side pressure plate 31 in the expansion / contraction direction M, and the nut 42 has a flange end face fixed to the drive-side pressure plate 31 and is threadedly engaged with the screw shaft 41 via numerous balls, so that the drive-side pressure plate 31 can be linearly moved in the expansion / contraction direction M in response to the rotation of the screw shaft 41. Note that the linear motion mechanism 40 is not limited to a ball screw, and a feed screw without balls may be used, or another linear motion mechanism may be adopted.

[0020] Furthermore, in this embodiment, a surface pressure distribution uniformity mechanism 50 capable of distributing the pressing force against the battery module 10 is provided between the cell-side pressure plate 32 and the drive-side pressure plate 31. The surface pressure distribution uniformity mechanism 50 of this embodiment has a plurality of springs 51 interposed in parallel between the cell-side pressure plate 32 and the drive-side pressure plate 31 as elastic pressure members. Note that various types of elastic bodies, such as springs and rubber, can be used as the elastic pressure members. The springs 51 of this embodiment are cylindrical coil springs. As shown in FIG. 3( a), eight cylindrical coil springs are arranged in parallel in a plan view (four in the longitudinal direction x two vertical rows = eight springs). In particular, in this embodiment, the cylindrical center of each cylindrical coil spring (the position indicated by the "x" symbol 51c in the figure) is located inside the projection plane of the electrode portion of the battery cell 12 (the shaded area indicated by the symbol 12m in the figure).

[0021] [Configuration of Battery Pack (Second Embodiment)] Next, a second embodiment of the battery pack will be described. Fig. 4 shows a schematic diagram of the second embodiment. As shown in Fig. 4, the battery pack 1 of the second embodiment includes two battery modules 10A, 10B inside a housing case 20. Note that each of the battery modules 10A, 10B has a configuration similar to that of the battery module 10 of the first embodiment, and therefore detailed description thereof will be omitted.

[0022] The battery pack 1 of the second embodiment includes a storage case 20 that stores two battery modules 10A, 10B at both ends of the battery pack 1, and a pressure device 30 that applies pressure to each of the battery modules 10A, 10B in the expansion / contraction direction M. As in the first embodiment, the storage case 20 is, for example, a rectangular parallelepiped metal housing, and stores each of the battery modules 10A, 10B in a storage position in which a plurality of battery cells 12 are stacked along the long side of the storage case 20.

[0023] As shown in the figure, the pressure device 30 of the second embodiment is disposed between two battery modules 10A, 10B. The pressure device 30 of the second embodiment includes a cell-side pressure plate 32 and a drive-side pressure plate 31 disposed opposite each battery module 10A, 10B in the expansion / contraction direction M, linear motion mechanisms 40A, 40B that change the opposing distance between the cell-side pressure plate 32 and the drive-side pressure plate 31 along the expansion / contraction direction M, and a drive mechanism 60 that drives each linear motion mechanism 10A, 10B.

[0024] The drive mechanism 60 of the second embodiment has one screw shaft 41 and two nuts 42A, 42B that are threaded onto the top and bottom of the screw shaft 41. The screw threads of one screw shaft 41 are set so that the feed direction is opposite for one battery module 10A and the other battery module 10B. Note that the number of screw shafts is not limited to one, and two shafts may be used, or a three-shaft configuration may be used in which the two screw shafts are fastened to a central shaft.

[0025] The drive mechanism 60 of the second embodiment has one worm wheel 62 fixed coaxially to the center of one screw shaft 41, and one motor 63 with one worm 61 that rotates the worm wheel 62 and is coaxially mounted on the tip of the output shaft. This makes it possible to drive the linear motion mechanisms 10A, 10B simultaneously, and in each battery module 10A, 10B inside the housing case 20, the multiple battery cells 12 are stacked and arranged in a state where they are constantly compressed in the expansion / contraction direction M by the pressure device 30.

[0026] [Effects of the Pressurizing Device] Next, the effects of the pressurizing device 30 of the first and second embodiments will be described. As described above, in a Li deposition-type all-solid-state battery, the amount of cell expansion is significantly larger than in a conventional liquid Lib-type secondary battery due to the use of Li metal in the negative electrode. Therefore, in order to accommodate the expansion of the battery module, it is necessary to make the volume of the feed screw larger than in the conventional battery.

[0027] On the other hand, increasing the volume of the feed screw portion of the linear motion mechanism 40 reduces the cell capacity, so it is desirable to configure the feed screw portion compactly. Furthermore, when replacing the battery cell 12, it is necessary to absorb displacement greater than the stroke required to release the confining pressure in the expansion / contraction direction M. In this case, if the lead screw portion of the linear motion mechanism 40 and the elastic portion of the surface pressure distribution uniformity mechanism 50 can share a portion of their occupied volume in the expansion / contraction direction M (Y dimension), it will be possible to move the required stroke without reducing the cell capacity.

[0028] However, the pressure structure described in Patent Document 1 is insufficient to achieve high surface pressure and a long stroke without reducing the cell capacity of the stacked battery cells 12. In other words, the technology described in Patent Document 1 places the lead screw drive mechanism and spring members independently at both ends of the battery module. This reduces the capacity of the stacked battery cells within the battery module. Furthermore, the technology described in Patent Document 1 places the spring members of the pressure structure only in the center of the pressure area, which causes uneven distribution of surface pressure applied to the battery module.

[0029] In contrast, the pressure applying device 30 of the first and second embodiments, as shown in FIGS. 1 and 4 , has a pair of opposing cell-side pressure applying plates 32 and drive-side pressure applying plates 31, a surface pressure distribution uniforming mechanism 50, a linear motion mechanism 40 using a feed screw, and a drive mechanism 60 that drives the mechanism, and employs a pressure applying structure in which the surface pressure distribution uniforming mechanism 50 is disposed between the pair of pressure applying plates 31, 32.

[0030] In particular, the linear motion mechanism 40 has a screw shaft 41 penetrating the cell-side pressure plate 32 in the expansion / contraction direction M, the surface pressure distribution uniform mechanism 50 is disposed between the cell-side pressure plate 32 and the drive-side pressure plate 31, and the drive mechanism 60 is positioned on the opposite side of the cell-side pressure plate 32 from the surface pressure distribution uniform mechanism 50. As shown in Figures 1 and 4 , the linear motion mechanism 40 and the surface pressure distribution uniform mechanism 50 are not independent, but can share a portion of their occupied volume in the expansion / contraction direction M (Y dimension), and can be disposed integrally in the expansion / contraction direction M. Therefore, the volume occupied by the pressure structure in the expansion / contraction direction M within the battery pack 1 can be reduced, thereby increasing the storage capacity of the battery cells 12 [Invention 1, Invention 11].

[0031] In other words, with the pressure device 30 of the first and second embodiments, by positioning the linear motion mechanism 40 using a feed screw so that it penetrates the cell-side pressure plate 32 in the expansion / contraction direction M, the linear motion mechanism 40 using a feed screw and the surface pressure distribution uniformity mechanism 50 can be positioned together in the stacking direction of the battery cells 12, rather than being independent. This makes it possible to compactly configure the volume occupied by the pressure device 30 in the expansion / contraction direction M, and to place more battery cells 12 in the space allocated for the springs 51.

[0032] Furthermore, with the pressure device 30 of the first and second embodiments, the surface pressure distribution uniformity mechanisms 50 are arranged in series in the stacking direction of the battery cells 12 and are interposed between the cell-side pressure plate 32 and the drive-side pressure plate 31. As shown in FIG. 5 , this arrangement makes it possible to control the surface pressure of the battery cells 12 using the energy stored in the surface pressure distribution uniformity mechanisms 50, and also serves as a displacement absorption mechanism in the expansion / contraction direction M of the battery cells 12.

[0033] This eliminates the need for fine displacement adjustments using a feed screw in the linear motion mechanism 40 to accommodate the required surface pressure during cell charging and discharging, reducing the workload of the drive mechanism 60. Furthermore, by interposing the surface pressure distribution uniformity mechanism 50 between the cell-side pressure plate 32 and the drive-side pressure plate 31, it is possible to absorb tilt and unevenness of the cell-side pressure plate 32 when absorbing displacement in the expansion / contraction direction M of the battery cells 12, thereby making the surface pressure distribution more uniform.

[0034] 1 , the pressure device 30 of the first embodiment applies pressure to a single battery module 10 stacked in the expansion / contraction direction M, thereby reducing the number of components required, such as the cell-side pressure plate 32, drive-side pressure plate 31, feed screw linear motion mechanism 40, and surface pressure distribution uniformity mechanism 50. This not only reduces weight and costs, but also increases the battery cell 12 storage capacity by the amount of the reduced mechanism volume [Invention 2].

[0035] Furthermore, in the pressure applying device 30 of the second embodiment, as shown in FIG. 4 , the pressure applying device 30 is disposed at the center of the storage case 20 in the expansion / contraction direction M, and the two upper and lower battery modules 10A, 10B stacked along the expansion / contraction direction M are simultaneously pressed at their respective center positions, so that the thrust force can be offset by the action-reaction force, which is advantageous in simplifying the structure [Invention 3].

[0036] Furthermore, in the pressure device 30 of the first and second embodiments, the surface pressure distribution uniformity mechanism 50 has multiple springs 51 arranged in parallel, as shown in Figures 1-4. This increases the ratio of the surface area occupied by the surface pressure distribution uniformity mechanism 50 to the electrode area of ​​the battery cell 12. Furthermore, if the multiple springs 51 are made of appropriate materials and designed with fatigue strength in mind, they can generate a stable load for a long period of time. Furthermore, since there are no problems with fluids, such as leaks and seals, the device can be maintenance-free [Invention 4].

[0037] Furthermore, in the pressure device 30 of the first and second embodiments, the multiple springs 51 are cylindrical coil springs. As shown in FIG. 3( a), in plan view, the cylindrical center 51c of each cylindrical coil spring 51 is located inside the projection surface 12m of the electrode portion of the battery cell 12. As shown in FIG. 3( b), the pressure device 30 of the first and second embodiments can alleviate stress on the edge portions of the battery cell 12 electrodes during pressure application. Furthermore, it can prevent or suppress breakdowns such as cracks at the edge of the electrode portion due to pressure application [Invention 5]. The two-dot chain line (32) in FIG. 3( b) illustrates the bending of the cell-side pressure plate due to uneven application of pressure force F when the elastic pressure member 50 is positioned in a way that prevents the pressure force from being distributed.

[0038] 6 and 7, in the pressure device 30 of the first and second embodiments, for example, a cylindrical slide guide 52 can be inserted coaxially with each cylindrical coil spring 51 along the expansion / contraction direction M into the cylinder of each cylindrical coil spring 51 to support the posture. As a result, according to the pressure device 30 of the first and second embodiments, each cylindrical coil spring 51 can be held in a predetermined position by the slide guide 52, more reliably preventing each cylindrical coil spring 51 from collapsing or falling off when expanding or contracting. Furthermore, each cylindrical coil spring 51 can be easily positioned during assembly [Invention 6].

[0039] 6, the slide guide 52 is fixed to the drive-side pressure plate 31, which prevents or suppresses deformation of the cell-side pressure plate 32 due to moments acting on the slide guide 52 caused by variations in flatness or thickness. This is therefore advantageous in preventing uneven distribution of surface pressure on the battery cells 12 [Invention 7].

[0040] Furthermore, in the pressure device 30 of the embodiment, there is a difference in thickness between the cell-side pressure plate 32 and the drive-side pressure plate 31. In the pressure device 30 of the embodiment, for example, as shown in FIG. 1-4, the "drive-side pressure plate thickness t>cell-side pressure plate thickness t" is satisfied. As a result, the pressure device 30 of the embodiment can reduce the volume of the mechanical section of the pressure device 30. Furthermore, the battery cell 12 storage capacity can be increased (the amount of stacked battery cells 12 can be increased) [Invention 8].

[0041] Furthermore, the pressure device 30 of the embodiment has a mechanism that allows the linear motion mechanism 40 using a feed screw to be rotated only from the drive mechanism 60 side, and has a self-locking mechanism that prevents the drive mechanism 60 side from being rotated from the linear motion mechanism 40 using a feed screw side, so that the pressure applied by the surface pressure distribution absorption mechanism 50 can be reliably maintained even when the drive mechanism 60 is stopped, as shown in Fig. 8. This is therefore more suitable for reducing the workload of the drive mechanism 60 [Invention 9].

[0042] As described above, the pressure applying device 30 of the first and second embodiments can reduce the volume of the mechanism and increase the cell capacity. The pressure applying device for a battery pack according to the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention.

[0043] For example, a modified example of the drive mechanism is shown in Fig. 9. As shown in Fig. 9, in the modified pressure device 30, the drive unit holder 70 is made up of a lower substrate 74 and an upper substrate 75 that are rectangular in plan view, and studs 76 that connect the upper and lower substrates 74, 75 at their four corners in the opposing direction. A motor 63 is fixed to the upper surface of the lower substrate 74, and the output of the motor 63 is transmitted to the worm wheel 62 via a worm, as in the above embodiment.

[0044] In this modified example, the worm wheel 62 is configured to rotate the lower part of the pinion shaft 71 located in the center inside the drive unit holder 70, and the rotational driving force of the pinion shaft 71 is transmitted from the pinion 72 on the upper part of the pinion shaft 71 through left and right driven gears 73A, 73B that mesh with the pinion 72, and can drive the screw shafts 41A, 41B of the left and right linear motion mechanisms 40A, 40B.

[0045] As a result, the pressure device 30 of this modified example has a plurality of linear motion mechanisms 40A, 40B using feed screws (two in parallel in the example shown in the figure), which reduces the load resistance required for each linear motion mechanism 40A, 40B using feed screws. Also, the volume of the drive unit holder 70 that houses the linear motion mechanisms 40A, 40B can be reduced [Invention 10].

[0046] REFERENCE SIGNS LIST 1 battery pack 10, 10A, 10B battery module 12 battery cell 20 storage case 30 pressure device 31 cell-side pressure plate 32 drive-side pressure plate 40, 40A, 40B linear motion mechanism using feed screw 41, 41A, 41B screw shaft 42, 42A, 42B nut 50, 50A, 50B surface pressure distribution uniformity mechanism 51 spring (cylindrical coil spring) 52 slide guide 60 drive mechanism 61 worm 62 worm wheel 63 motor 70 drive unit holder 71 pinion shaft 72 pinion 73A, 73B driven gear 74 lower substrate 75 upper substrate 76 stud M extension / contraction direction

Claims

1. A pressing device used for a battery pack including a battery module in which a plurality of battery cells are stacked, the pressing device pressing the plurality of battery cells in the stacking expansion / contraction direction, the pressing device including: a cell-side pressing plate and a drive-side pressing plate that are arranged to face each other in the expansion / contraction direction with respect to the battery module; a surface pressure distribution uniform mechanism that is provided between the cell-side pressing plate and the drive-side pressing plate and can disperse the pressing force applied to the battery module; a linear motion mechanism using a feed screw that can move the facing distance between the cell-side pressing plate and the drive-side pressing plate along the expansion / contraction direction; and a drive mechanism that is arranged on the opposite side of the surface pressure distribution uniform mechanism with respect to the drive-side pressing plate and drives the linear motion mechanism. The pressing device for a battery pack is characterized by including the above components.

2. The pressing device for a battery pack according to claim 1, which presses one battery module stacked along the expansion / contraction direction.

3. The pressing device for a battery pack according to claim 1, which presses two battery modules stacked along the expansion / contraction direction.

4. The pressing device for a battery pack according to claim 1, wherein the surface pressure distribution uniform mechanism has a plurality of springs that are arranged in parallel between the cell-side pressing plate and the drive-side pressing plate.

5. The pressing device for a battery pack according to claim 4, wherein the spring is a cylindrical coil spring, and in a plan view, the center of the cylinder of each cylindrical coil spring is located inside the projection surface of the electrode portion of the battery cell.

6. The pressing device for a battery pack according to claim 4, wherein the spring is a cylindrical coil spring, and a slide guide that guides along the expansion / contraction direction passes through the cylinder of each cylindrical coil spring.

7. The pressing device for a battery pack according to claim 6, wherein the slide guide is fixed to the cell-side pressing plate.

8. The pressing device for a battery pack according to claim 1, wherein the plate thickness of the cell-side pressing plate and the plate thickness of the drive-side pressing plate are different from each other.

9. The pressing device for a battery pack according to claim 1, wherein the drive mechanism has a self-locking mechanism that can drive the linear motion mechanism only by a rotational operation from the drive mechanism side, and the self-locking mechanism makes the drive mechanism side non-rotatable from the linear motion mechanism side.

10. The battery pack pressurizing device according to claim 1, having a plurality of linear motion mechanisms.

11. A battery pack comprising a battery module in which a plurality of battery cells are stacked, and a pressurizing device that pressurizes the plurality of battery cells in the stacking expansion / contraction direction thereof, wherein the pressurizing device is the battery pack pressurizing device according to any one of claims 1 to 10.

Images