Battery pack water cooling device, design method thereof, battery pack and vehicle thereof

Abstract

The application discloses a battery pack water cooling device and a design method thereof, a battery pack and a vehicle thereof, and is used for providing a cooling structure for a battery cell of the battery pack. The battery pack water cooling device comprises a plurality of water cooling devices arranged at intervals. Spaces for accommodating the battery cells are arranged between adjacent water cooling devices. The water cooling device comprises a first flat plate and a second flat plate. A flow guide strip for providing a flow channel for a cooling liquid is arranged between the first flat plate and the second flat plate. The water cooling device of the application is no longer arranged at the bottom, but is arranged on a larger area of the square battery cell. The cooling area can be increased by several times. The heat conduction path is changed from the height direction of the battery cell to the thickness direction of the battery cell. The heat conduction path is greatly shortened. The cooling capacity and the battery charging speed are greatly improved. Meanwhile, the water cooling device arranged in the transverse direction can play a role of a cross beam. The structural strength of the battery pack is improved. The number of the cross beams of the battery pack is reduced. More battery cells can be accommodated.

Description

Technical Field

[0001] This invention relates to a water-cooling device and its design method, a battery pack and its vehicle, and more particularly to a battery pack water-cooling device and its design method, a battery pack and its vehicle. Background Technology

[0002] Currently, most commercially available power batteries using square cells rely on water cooling at the bottom of the cell. This means the water cooling device is directly attached to the bottom of the cell, typically consisting of two brazed stamped aluminum plates with an internal cavity for coolant flow. The drawback of this existing technology is the small area of ​​the cell's bottom surface. Furthermore, the heat from the cell must be transferred downwards along its height to the bottom water cooling device, resulting in a long heat conduction path and limited cooling capacity. Additionally, the bottom water cooling device is usually quite thick to ensure structural strength, and the presence of reinforcing beams within the battery pack further restricts the space available to accommodate the cells. Therefore, current power battery technology suffers from two major drawbacks: first, the large space occupied by structural components hinders further increases in battery capacity; second, limited battery cooling capacity restricts charging speed.

[0003] Existing technology has disclosed a battery pack and a water-cooling device, in which the water-cooling device contacts the larger side of the battery cell, and each battery cell has water-cooling devices on both sides. The water-cooling device has a deformable and collapsible interlayer inside, which absorbs the expansion of the battery cell by deforming. The shortcomings of this solution are: 1. After the water-cooling device collapses and deforms, the wall of its coolant reservoir may be damaged, leading to leakage; 2. After the water-cooling device deforms, its flow resistance may change, affecting the flow uniformity of each branch and thus increasing the temperature difference; 3. The water-cooling device is made of extruded profile material, which is relatively soft and cannot support the weight of the battery. Summary of the Invention

[0004] The purpose of this invention is to provide a battery pack water cooling device and its design method, battery pack and vehicle. The first technical problem to be solved is to overcome the problems of long heat conduction paths and limited cooling capacity in the prior art. The second technical problem to be solved is to provide more storage space for the battery pack while cooling. The last technical problem to be solved is to improve the structural strength of the battery pack and accommodate more cells while achieving the cooling effect.

[0005] This invention provides the following solution:

[0006] A battery pack water cooling device is provided for providing a cooling structure for the battery cells of the battery pack. The battery pack water cooling device includes a plurality of water cooling devices 300 arranged at intervals. A space for accommodating battery cells 100 is provided between adjacent water cooling devices. Each water cooling device 300 includes a first plate 301 and a second plate 302. A guide strip 304 for providing a flow channel for coolant is provided between the first and second plates.

[0007] Furthermore, the water-cooling device 300 is flat, and the water-cooling devices 300 are arranged parallel to each other and spaced apart in the housing 200. The first flat plate 301 and the second flat plate 302 are fixedly connected by a connector 305.

[0008] Furthermore, one side of the water-cooling device 300 is in contact with an adjacent battery cell, and the other side has a gap with the adjacent battery cell for absorbing expansion.

[0009] Furthermore, the water cooling device 300 includes one or more water cooling device components, each of which is provided with an inlet and an outlet. Different water cooling device components are connected by pipes 400 to form a flow channel for coolant.

[0010] Furthermore, the water-cooling device is flat, with a thickness of 1mm to 3mm, and its height is 10mm to 20mm less than the height of the battery cell.

[0011] A design method for a water-cooling device for a battery pack, specifically including:

[0012] Determine the target values ​​for the expansion force and cavity thickness change rate of a single battery cell;

[0013] Calculate the sum of the widths of all guide strips;

[0014] Assign an initial value to the number of guide strips;

[0015] Calculate the deformation of the water-cooling device wall after it is compressed by the battery cell;

[0016] Calculate the rate of change of cavity thickness in a water-cooled device after it is subjected to expansion and compression.

[0017] The cavity thickness change rate after expansion and compression is compared with the target value of the cavity thickness change rate. If the cavity thickness change rate after expansion and compression is greater than or equal to the target value of the cavity thickness change rate, the initial value of the guide strip is reassigned. Specifically, the initial value is incremented by one, and the deformation of the water-cooling device wall after being squeezed by the battery cell is calculated until the current number of guide strips meets the design requirements. The width of the guide strip is then calculated. Alternatively, if the cavity thickness change rate after expansion and compression is less than the target value of the cavity thickness change rate, it is determined that the current number of guide strips meets the design requirements, and the width of the guide strip is then calculated.

[0018] A battery pack includes battery cells 100 and a housing 200 for storing the battery cells. The battery pack is equipped with a battery pack water cooling device, and the housing of the battery pack has one or more receiving cavities for accommodating the battery cells and the water cooling device.

[0019] Furthermore, the terminals and explosion-proof valves inside the battery pack face directly upwards.

[0020] Furthermore, the battery cell is a cuboid.

[0021] A vehicle having a battery pack installed therein.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] The water-cooling device of this invention is no longer placed at the bottom, but is arranged on a larger surface of the square battery cell. This increases the cooling area several times over, and the heat conduction path changes from the height direction of the battery cell to the thickness direction, significantly shortening the heat conduction path and resulting in a substantial improvement in cooling capacity and battery charging speed. Simultaneously, the horizontally positioned water-cooling device acts as a crossbeam, increasing the structural strength of the battery pack, reducing the number of crossbeams, and allowing for the accommodation of more battery cells.

[0024] In this invention, each battery cell has a water-cooling device on only one side, while the other side has a structure that can absorb the expansion of the battery cell. The water-cooling device is deformation-free, has more reliable structural strength, is less prone to leakage, and has more stable flow uniformity, which is more conducive to temperature difference control. The water-cooling device involved in this invention is not an extruded profile, but a rolled aluminum plate, which has higher strength and greater reliability. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the battery pack structure of the present invention.

[0027] Figure 2 This is a schematic diagram of the battery cell and water cooling device of the present invention.

[0028] Figure 3 This is a schematic diagram of the water cooling device.

[0029] Figure 4 This is a diagram showing the connection relationship between the battery cell, battery module and water cooling device in the embodiment.

[0030] Figure 5yes Figure 4 A magnified view of a portion of the image.

[0031] Figure 6 This is a structural diagram of a single battery module.

[0032] Figure 7 This is an exploded view of a single battery module.

[0033] Figure 8 yes Figure 7 A magnified view of a portion of the image.

[0034] Figure 9 This is a structural diagram of a single battery module that hides some of the battery cells while revealing the water-cooling device.

[0035] Figure 10 This is a structural diagram of the battery pack (front view).

[0036] Figure 11 This is a 3D structural diagram of the battery pack.

[0037] Figure 12 This is a flowchart of the design method for a battery pack water cooling device. Detailed Implementation

[0038] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] like Figures 1 to 11 The battery pack water cooling device shown is a water cooling device 300 used to provide a cooling structure for the battery cells of the battery pack. The battery pack water cooling device includes a number of water cooling devices 300 arranged at intervals. A space for accommodating the battery cells 100 is provided between adjacent water cooling devices. The water cooling device 300 includes a first plate 301 and a second plate 302. A guide strip 304 for providing a flow channel for the coolant is provided between the first and second plates.

[0040] Specifically, the water-cooling device 300 is flat and is arranged parallel to each other and spaced apart in the housing 200. The first flat plate 301 and the second flat plate 302 are fixedly connected by a connector 305.

[0041] For example, the water cooling device is flat, with a thickness of 1mm to 3mm, and its height is 10mm to 20mm less than the height of the battery cell.

[0042] For example, the battery cell is rectangular, and multiple cells are contained in a battery pack. It can be a hard-shell lithium battery or a pouch lithium battery. The terminals and explosion-proof valve of the cell are located on the top surface of the cell. The cell width ranges from 150mm to 2000mm, the cell thickness from 10mm to 60mm, and the cell height from 80mm to 150mm.

[0043] Specifically, one side of the water-cooling device 300 is in contact with an adjacent battery cell, for example, by bonding, while the other side has a gap with the adjacent battery cell for absorbing expansion.

[0044] Specifically, the water cooling device 300 includes one or more water cooling device components. Each water cooling device component is provided with an inlet 401 and an outlet 402. Different water cooling device components are connected by pipes 400 to form a flow channel for coolant. After connection, the entire water cooling device components share a common inlet 401 and outlet 402.

[0045] The present invention discloses a battery pack and a vehicle equipped with the battery pack. The battery pack includes a battery cell 100 and a housing 200 for storing the battery cell. A water cooling device 300 is provided inside the battery pack. The housing of the battery pack has one or more receiving cavities for accommodating the battery cell and the water cooling device 300.

[0046] Specifically, the terminals and explosion-proof valve inside the battery pack face directly upwards, and the battery cell is a cuboid, with the largest surface area of ​​the six surfaces of the cuboid cell facing forward. Depending on the specific operating conditions, those skilled in the art can determine which direction "forward" refers to in the specific operating conditions and will ensure that the largest surface area of ​​the six surfaces of the cuboid cell faces forward.

[0047] The water-cooling device is flat, with a thickness of 1mm to 3mm, and its height is 10mm to 20mm less than that of the battery cell. The water-cooling device has channels for coolant to flow inside, and there are one or more housing cavities inside the battery pack housing to accommodate the battery cell and the water-cooling device.

[0048] Inside the battery pack, the terminals and explosion-proof valves of the battery cells face directly upwards, and the largest surface area of ​​the six sides of the cell faces forward. One of the two largest surfaces of each cell contacts a water-cooling device. The other largest surface of that cell is adjacent to the largest surface of another cell, with a gap between them to absorb cell expansion; a limit device is located within this gap. Each water-cooling device simultaneously contacts the largest surfaces of multiple cells, and both sides of each device are in contact with cells. Adhesive is used to connect the water-cooling devices to the cell contact surfaces. The water-cooling devices are arranged in parallel and connected in parallel via piping.

[0049] In the battery pack, multiple water-cooling devices arranged in parallel are divided into one or more groups. The water-cooling devices in each group are connected in parallel, and each group has one inlet and one outlet. The groups are then connected in parallel through pipes, and after connection, they have a common inlet and a common outlet. For any two water-cooling devices in each group, the cross-sectional area of ​​the flow channel in the water-cooling device closer to the inlet of the group is not greater than the cross-sectional area of ​​the flow channel in the water-cooling device farther away from the inlet of the group.

[0050] The water-cooling device 300 in this embodiment of the invention is flat and has a thickness of 1mm to 3mm. The height of the water-cooling device 300 is 10mm to 20mm smaller than the height of the battery cell. Each water-cooling device 300 has at least one water inlet and at least one water outlet.

[0051] The water-cooling device 300 includes at least a first plate 301, a second plate 302, a frame 303, a flow guide 304, and a connector, all connected by brazing. The first plate 301 and the second plate 302 are both flat, made of aluminum, and 0.1mm to 1mm thick. The first plate 301 and the second plate 302 have identical external dimensions. The frame 303 is an aluminum plate with a brazing filler composite layer on both sides. The frame 303 has a thickness of 0.3mm to 2mm. The outer edge of the frame 303 has the same outline as the outer edges of the first plate 301 and the second plate 302, and the width of the frame 303 is 3mm to 10mm.

[0052] There are one or more guide strips 304, made of the same material and with the same thickness as the frame. The width of the guide strips 304 is 3mm to 5mm, and each guide strip 304 has the same dimensions. The guide strips are located between the first plate 301 and the second plate 302. Multiple guide strips 304 are evenly distributed in the height direction of the water cooling device. Each guide strip 304 is in contact with both the first plate 301 and the second plate 302 simultaneously. Depending on the number of guide strips, the cross-sectional area of ​​the channel in the water cooling device 300 that allows coolant to flow is different.

[0053] This invention also discloses a vehicle equipped with the battery pack disclosed in this invention. The advantage of this invention is that the water-cooling device is no longer placed at the bottom, but rather arranged on the large surface of the square battery cell, increasing the cooling area several times over. Furthermore, the heat conduction path changes from the height direction of the battery cell to the thickness direction, significantly shortening the heat conduction path and thus greatly improving cooling capacity and battery charging speed. Moreover, the horizontally positioned water-cooling device in this invention acts as a crossbeam, increasing the structural strength of the battery pack, reducing the number of crossbeams, and allowing for more battery cells to be accommodated. In addition, in this invention, the water-cooling device simultaneously functions as a crossbeam, reducing the number of crossbeams within the battery pack, saving space, and increasing battery capacity.

[0054] like Figure 12 As shown in the figure, this invention also discloses a design method for a water-cooling device for a battery pack, specifically including:

[0055] Step S1: Determine the expansion force F and the target value μ0 of the cavity thickness change rate of a single cell. The expansion force F can be obtained through actual measurement of the cell, and the target value μ0 of the cavity thickness change rate can be determined according to specific circumstances.

[0056] Step S2, calculate the sum D of the widths of all guide strips 304:

[0057]

[0058] In the formula, L is the cell width, σ 0.2 ξ is the yield strength of the guide strip material, and ξ is the safety factor, which is 1.2 in this embodiment of the invention;

[0059] Step S3: Assign an initial value to the quantity n of the guide strips 304;

[0060] Step S4: Calculate the deformation ω of the water-cooling device wall after being squeezed by the battery cell:

[0061]

[0062] In the formula, q is the linear load of the cell expansion force in the height direction of the water cooling device, which satisfies:

[0063]

[0064] Where H is the height of the water cooling device, and l is the distance between the two guide vanes, H and l satisfy:

[0065]

[0066] E is the elastic modulus of the materials of the first plate 301 and the second plate 302, and I is the moment of inertia of the cross sections of the first plate 301 and the second plate 302. E and I satisfy:

[0067]

[0068] Where t1 is the thickness of the first plate 301 and the second plate 302;

[0069] Step S5: Calculate the rate of change μ of the cavity thickness of the water-cooling device after the battery cell expands and compresses it.

[0070]

[0071] Where t2 is the cavity thickness;

[0072] Step S6: Compare the cavity thickness change rate μ after cell expansion and extrusion with the target value μ0 of the cavity thickness change rate. If μ ≥ μ0, proceed to step S7; if μ < μ0, proceed to step S8.

[0073] Step S7: Reassign the number of guide strips n, with the new value increasing by 1 compared to the previous assignment, and proceed to step S3;

[0074] Step S8: The current number of guide strips n meets the design requirements. Calculate the width d of the guide strips according to the following formula:

[0075]

[0076] Where D is the sum of the widths of all guide strips 304.

[0077] The control logic of step S6 can be summarized as follows: compare the cavity thickness change rate after expansion and compression with the target value of the cavity thickness change rate. If the cavity thickness change rate after expansion and compression is greater than or equal to the target value of the cavity thickness change rate, then reassign the initial value of the guide strip. Specifically, increment the initial value by one and continue to calculate the deformation of the water-cooling device wall after being squeezed by the battery cell until the current number of guide strips meets the design requirements. Calculate the width of the guide strip. Alternatively, if the cavity thickness change rate after expansion and compression is less than the target value of the cavity thickness change rate, determine that the current number of guide strips meets the design requirements and calculate the width of the guide strip.

[0078] As can be seen from the above description of the embodiments of the present invention, the advantages of the embodiments of the present invention are at least as follows:

[0079] (1) The heat dissipation area is greatly increased and the heat conduction path is greatly shortened, which leads to a significant improvement in cooling capacity.

[0080] (2) The water cooling device acts as a crossbeam, and the battery pack is no longer under the crossbeam, saving space and increasing power.

[0081] (3) The design method provided by the present invention can make the water cooling device have sufficient structural strength and improve its reliability.

[0082] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0083] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, any of the embodiments claimed in the claims can be used in any combination.

[0084] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0085] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0086] In addition, the functional modules in the various embodiments of the present invention can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0087] All features disclosed in this specification, or steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps. Any feature disclosed in this specification, unless specifically stated otherwise, may be replaced by other equivalent or similar features. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features. Throughout this specification, the same reference numerals indicate the same elements.

[0088] Those skilled in the art will understand that modules in the device of the embodiments can be adaptively changed and placed in one or more devices different from that embodiment. Modules, units, or components in the embodiments can be combined into a single module, unit, or component, and further, they can be divided into multiple sub-modules, sub-units, or sub-components. Except where at least some of such features and / or processes or units are mutually exclusive, any combination can be used to combine all features disclosed in this specification (including the corresponding claims, abstract, and drawings) and all processes or units of any method or device so disclosed. Unless expressly stated otherwise, each feature disclosed in this specification (including the corresponding claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose.

[0089] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order and can be interpreted as names.

[0090] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "top," and "bottom," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0091] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0092] The terms "comprising" or "including" as used in the specification and claims are open-ended and should be understood as "including but not limited to". Preferred embodiments of the invention will be described subsequently; however, this description is for the purpose of understanding the general principles of the specification and is not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0093] It should be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0094] In the several embodiments provided by this invention, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for example, the division of units is merely a logical functional division, and other division methods may exist in actual implementation; for example, multiple units or components may be combined or integrated into another system, or some features may be ignored, or certain instructions may not be executed. Furthermore, the couplings or direct couplings or communication connections shown or discussed may be indirect couplings or communication connections through some interfaces, apparatuses, or units, and may be electrical, mechanical, or other forms not shown.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A design method for a water-cooling device for a battery pack, characterized in that, Specifically, it includes: Determine the target values ​​for the expansion force and cavity thickness change rate of a single battery cell; Calculate the sum of the widths of all guide strips; Assign an initial value to the number of guide strips; Calculate the deformation of the water-cooling device wall after it is compressed by the battery cell; Calculate the rate of change of cavity thickness in a water-cooled device after it is subjected to expansion and compression. The cavity thickness change rate after expansion and compression is compared with the target value of the cavity thickness change rate. If the cavity thickness change rate after expansion and compression is greater than or equal to the target value of the cavity thickness change rate, the initial value of the guide strip is reassigned. Specifically, the initial value is incremented by one, and the deformation of the water-cooling device wall after being squeezed by the battery cell is calculated until the current number of guide strips meets the design requirements. The width of the guide strip is then calculated. Alternatively, if the cavity thickness change rate after expansion and compression is less than the target value of the cavity thickness change rate, it is determined that the current number of guide strips meets the design requirements, and the width of the guide strip is then calculated. The water cooling device (300) includes a first plate (301) and a second plate (302), and a guide strip (304) is provided between the first and second plates to provide a flow channel for the coolant.

2. A battery pack water cooling device for providing a cooling structure for the battery cells of the battery pack, characterized in that, The battery pack water cooling device is designed by the battery pack water cooling device design method of claim 1; The battery pack water cooling device includes several spaced water cooling devices (300), with space provided between adjacent water cooling devices for accommodating battery cells (100).

3. The battery pack water cooling device according to claim 2, characterized in that, The water cooling device (300) is flat and is arranged in parallel and spaced apart in the box (200). The first flat plate (301) and the second flat plate (302) are fixedly connected by a joint (305).

4. The battery pack water cooling device according to claim 2, characterized in that, One side of the water cooling device (300) is in contact with an adjacent battery cell, and the other side has a gap with the adjacent battery cell for absorbing expansion.

5. The battery pack water cooling device according to claim 2, characterized in that, The water cooling device (300) includes one or more water cooling device components, each of which is provided with an inlet and an outlet. Different water cooling device components are connected by pipes (400) to form a flow channel for coolant.

6. The battery pack water cooling device according to claim 2, characterized in that, The water-cooling device is flat, with a thickness of 1mm to 3mm, and its height is 10mm to 20mm less than that of the battery cell.

7. A battery pack, comprising battery cells (100) and a housing (200) for storing the battery cells, characterized in that, The battery pack is provided with a battery pack water cooling device as described in any one of claims 2 to 6, and the battery pack housing has one or more receiving cavities for accommodating the battery cells and the water cooling device.

8. The battery pack according to claim 7, characterized in that, The terminals and explosion-proof valves inside the battery pack face directly upwards.

9. The battery pack according to claim 7, characterized in that, The battery cell is a cuboid.

10. A vehicle, characterized in that, The vehicle is equipped with the battery pack as described in claim 8 or 9.

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