Battery module and battery pack

Abstract

The utility model provides a battery module and a battery pack. The battery module comprises a cooling device and a plurality of single batteries, the cooling device comprises a first cooling plate; each single battery comprises a shell, an electrode assembly and two first current collecting pieces, the shell is provided with an end plate, the electrode assembly is arranged in the shell, and the electrode assembly comprises a first pole piece; wherein the two first current collecting pieces are located at the two ends, in the axial direction, of the electrode assembly and electrically connected to the first pole piece, the first current collecting piece close to the end plate comprises a heat conduction part, the heat conduction part is connected with the side, close to the electrode assembly, of the end plate, and the side, away from the electrode assembly, of the end plate is connected with the first cooling plate. The utility model aims to solve the technical problems that the existing battery module is low in cooling efficiency and is easy to cause thermal runaway.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and in particular to a battery module and a battery pack. Background Art

[0002] Thermal management has always been a focus for new energy vehicles. As the energy and power densities of these vehicles' power batteries continue to increase, battery heat generation increases, making heat dissipation systems with fast cooling speeds and high heat transfer coefficients increasingly crucial. Cylindrical battery technologies employ serpentine cooling systems around the sides of the individual cells in the battery module. However, the axial thermal conductivity of cylindrical batteries is much greater than their diametrical thermal conductivity, resulting in low cooling efficiency and a high risk of thermal runaway. Utility Model Content

[0003] The embodiments of the present invention provide a battery module and a battery pack, which are intended to solve the technical problems of low cooling efficiency and susceptibility to thermal runaway in existing battery modules.

[0004] In a first aspect, an embodiment of the present invention provides a battery module, comprising:

[0005] a cooling device comprising a first cooling plate; and

[0006] A plurality of single cells, each of the single cells comprising a housing, an electrode assembly, and two first current collectors, the housing having an end plate, the electrode assembly being disposed within the housing, and the electrode assembly comprising a first electrode sheet;

[0007] Among them, the two first current collecting parts are located at both ends of the electrode assembly along the axial direction and are electrically connected to the first pole piece. The first current collecting part close to the end plate includes a heat conducting part, and the heat conducting part is connected to the side of the end plate close to the electrode assembly. The side of the end plate facing away from the electrode assembly is connected to the first cooling plate.

[0008] In one embodiment, the heat-conducting portion includes a first heat-conducting surface facing the end plate, the first heat-conducting surface is connected to the end plate, the end plate includes a second heat-conducting surface facing the first cooling plate, the second heat-conducting surface is connected to the first cooling plate, the area of ​​the first heat-conducting surface is S1, and the area of ​​the second heat-conducting surface is S2, wherein S1:S2=(0.05~0.25):1.

[0009] In one embodiment, the top surface of the end plate is formed with a groove opening toward the electrode assembly, the groove has a bottom wall and an inner side wall connected to the bottom wall, and the heat conducting portion is disposed in the groove and connected to the bottom wall.

[0010] In one embodiment, the inner side wall is inclined relative to the bottom wall, and an angle α between the inner side wall and the bottom wall is α, wherein 105°≤α≤135°.

[0011] In one embodiment, the end plate has a first portion and a second portion disposed around the first portion, and the groove is formed on the first portion;

[0012] A vertical distance between the bottom wall and a side surface of the end plate facing away from the electrode assembly is H1, and a thickness of the second portion is H2, wherein H1:H2=(0.3-0.6):1.

[0013] In one embodiment, first electrode tabs with the same polarity are provided at both ends of the first electrode piece, and the two first current collecting members are connected to the two first electrode tabs respectively.

[0014] In one embodiment, the first current collecting member further includes a current collecting portion and a connecting portion, the current collecting portion is connected to the electrode assembly, the connecting portion is connected between the current collecting portion and the heat conducting portion, and the connecting portion is inclined relative to the heat conducting portion.

[0015] In one embodiment, the angle between the connecting portion and the heat conducting portion is β, wherein 105°≤β≤135°.

[0016] In one embodiment, a vertical distance between the bottom wall of the groove and a side surface of the end plate facing away from the electrode assembly is H1, and a thickness of the heat conducting portion is H3, wherein H3:H1=(0.2-1.2):1.

[0017] In one embodiment, a side surface of the end plate facing the first cooling plate is flat.

[0018] In one embodiment, the cooling device further includes a cooling assembly, which includes a plurality of second cooling plates extending from the first cooling plate on a side close to the single cell, the plurality of second cooling plates being connected to the first cooling plate, and the second cooling plates being thermally conductively connected to the radial side walls of the single cell.

[0019] In one embodiment, the first current collecting member is welded to the end plate.

[0020] In one embodiment, the welding area between the first current collecting member and the end plate is S3, wherein S3:S2=(0.01-0.05):1.

[0021] In a second aspect, an embodiment of the present invention further provides a battery pack comprising the above-mentioned battery module.

[0022] Beneficial effects of the embodiments of the present utility model:

[0023] In the technical solution of the present utility model, the two first current collecting members are located at both ends of the electrode assembly, and the two first current collecting members are electrically connected to the two first pole pieces, thereby realizing axial overcurrent, resulting in an increase in axial heat. The first current collecting member is directly connected to the shell, and the first cooling plate is arranged below the plurality of single cells. The bottom of the single cell is cooled by the first cooling plate, and the top of the single cell can dissipate heat by contact with the air, thereby realizing axial heat dissipation of the single cell and improving the heat dissipation capacity of the battery module, thereby achieving better control of the temperature of the battery module, and making the battery module suitable for fast charging and discharging occasions such as high-rate discharge. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 This is a three-dimensional schematic diagram of a battery module provided by an embodiment of the present utility model;

[0026] Figure 2 yes Figure 1 Top view of the battery module;

[0027] Figure 3 yes Figure 2 Cross-sectional view of AA;

[0028] Figure 4 yes Figure 3 A magnified schematic diagram of B in the middle;

[0029] Figure 5 yes Figure 1 The main view of the single cell battery;

[0030] Figure 6 yes Figure 5 An enlarged schematic diagram of the partial section at point C in the middle;

[0031] Figure 7 yes Figure 6 It is an enlarged schematic diagram of point D;

[0032] Figure 8 yes Figure 1 Schematic diagram of the structure of the cooling component;

[0033] Figure 9 It is a schematic diagram of temperature test points of a single battery provided by an embodiment of the present utility model.

[0034] Explanation of Figure Numbers

[0035]

[0036] DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention. In the present invention, unless otherwise specified, the directional words used, such as "upper" and "lower", generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inside" and "outside" refer to the outline of the device.

[0038] Thermal management has always been a focus for new energy vehicles. As the energy and power densities of new energy vehicle batteries continue to increase, battery heat generation increases, making heat dissipation systems with fast cooling speeds and high heat transfer coefficients increasingly important. Cylindrical battery technologies utilize serpentine cooling systems around the sides of the individual cells in the battery module. However, the axial thermal conductivity of cylindrical batteries is much greater than the diametrical thermal conductivity, resulting in low cooling efficiency and a high risk of thermal runaway.

[0039] In view of this, the present invention proposes a battery module. Figures 1 to 8 This is a structural schematic diagram of an embodiment of a battery module provided by the present invention. The battery module provided by the present invention has high cooling efficiency, high safety, and low probability of thermal runaway. The battery module will be described in detail below in conjunction with the main drawings.

[0040] See also Figure 1 、 Figure 2 and Figure 3The battery module 100 includes a cooling device 101 and a plurality of single cells 103, the cooling device 101 includes a first cooling plate 102; each of the single cells 103 includes a shell 104, an electrode assembly 105 and two first current collectors 106, the shell 104 has an end plate 107, the end plate 107 and the other parts of the shell can be integrally arranged or separately arranged, the electrode assembly 105 is arranged in the shell 104, and the electrode assembly 105 includes a first pole piece; wherein, the two first current collectors 106 are located at both ends of the electrode assembly 105 in the axial direction and are electrically connected to the first pole piece, the first current collector 106 close to the end plate 107 includes a heat conducting portion 110, the heat conducting portion 110 is connected to one side of the electrode assembly 105 of the end plate 107, and the side of the end plate 107 facing away from the electrode assembly 105 is connected to the first cooling plate 102.

[0041] In this embodiment, the electrode assembly 105 includes a first electrode sheet, a diaphragm and a second electrode sheet that are wound together. The diaphragm is located between the first electrode sheet and the second electrode sheet, wherein the polarities of the first electrode sheet and the second electrode sheet are opposite. Each of the single cells 103 also includes two first current collectors 106 and two second current collectors. The two first current collectors 106 are located at both ends of the electrode assembly 105 and are electrically connected to the first electrode sheet. The two second current collectors are located at both ends of the electrode assembly 105 and are electrically connected to the second electrode sheet. Such an arrangement can provide The current collecting capacity of the single cell 103 is improved, but due to the axial overflow of the electrode assembly 105 along the single cell 103, the axial heat generation of the single cell 103 will increase, and then the axial heat of the single cell 103 will be too high. Therefore, a first cooling plate 102 is set at the bottom of the single cell 103. The cooling method of the first cooling plate 102 includes but is not limited to air cooling, liquid cooling or direct cooling. The single cell 103 is cooled and heat exchanged in the axial direction through the first cooling plate 102, thereby improving the cooling efficiency of the battery module 100.

[0042] In the technical solution of the present utility model, the first current collecting member 106 is connected to the shell 104, and the first cooling plate 102 is arranged under the plurality of single cells 103. The bottom of the single cell 103 is cooled by the first cooling plate 102, and the top of the single cell 103 can dissipate heat by contact with the air, thereby achieving simultaneous heat transfer from the top and bottom of the single cell 103 for dissipation, improving the axial heat dissipation capacity of the battery module 100, thereby achieving better control of the temperature of the battery module 100, and making the battery module 100 suitable for fast charging and discharging occasions such as high-rate discharge.

[0043] For ease of description, the side of the end plate 107 close to the battery assembly 105 is a top surface 109 , and the side of the end plate away from the electrode assembly 105 is a bottom surface 108 .

[0044] It should be noted that, in some embodiments, the first cooling plate 102 is made of an insulating material. In another embodiment, an insulating layer is provided on a side of the first cooling plate 102 facing the plurality of battery cells, and the insulating layer is capable of conducting heat.

[0045] In some embodiments, the heat conducting portion 110 is used to transfer the heat of the first current collecting member 106 to the end plate 107, and the end plate 107 then transfers the heat to the first cooling plate 102, and the first cooling plate 102 takes the heat away, thereby achieving heat dissipation. Specifically, the heat conducting portion 110 includes two first side surfaces arranged opposite to each other, one of which is arranged toward the end plate 107, and the first side surface arranged toward the end plate 107 is a first heat conducting surface 111, and the first heat conducting surface 111 is connected to the end plate 107, and the first heat conducting surface 111 is used to transfer heat to the end plate 107. Further, the end plate 107 includes two first side surfaces arranged opposite to each other, and one of the first side surfaces is arranged toward the end plate 107, and the first side surface arranged toward the end plate 107 is a first heat conducting surface 111, and the first heat conducting surface 111 is connected to the end plate 107, and the first heat conducting surface 111 is used to transfer heat to the end plate 107. Further, the end plate 107 includes two first side surfaces arranged opposite to each other. Two second side surfaces are set, one of which is set toward the heat-conducting part 110, and the other second side surface is set toward the first cooling plate 102. The second side surface facing the heat-conducting part 110 is a second heat-conducting surface 112, and the second heat-conducting surface 112 is connected to the first cooling plate 102. Specifically, the heat generated by the electrode assembly 105 and the first current collecting part 106 is transferred to the heat-conducting part 110, and the heat-conducting part 110 transfers the heat to the end plate 107 through the first heat-conducting surface 111, and the end plate 107 transfers the heat to the first cooling plate 102 through the second heat-conducting surface 112, thereby realizing heat transfer.

[0046] It should be noted that both ends of the electrode assembly 105 of the single cell 103 provided in this embodiment have current collecting capabilities. In this embodiment, the first current collector 106 is a negative electrode current collector, and the single cell 103 also includes two second current collectors, and the two second current collectors are positive electrode current collectors. The arrangement of the first current collector 106 and the second current collector is not limited, as long as current transfer can be achieved. Specifically, in this embodiment, taking the end of the single cell 103 close to the first cooling plate 102 as an example, the second current collector is arranged around the first current collector 106, and the first current collector 106 is connected to the first electrode piece.

[0047] Further, in some embodiments, see Figure 5 and Figure 6The area of ​​the first heat conducting surface 111 is S1, and the area of ​​the second heat conducting surface 112 is S2, where S1:S2 = (0.05-0.25):1. In this embodiment, the first current collector 106 and the second current collector are both provided at one end of the single battery 103 close to the first cooling plate 102. The area of ​​the first current collector 106 should not be too large or too small. If the area of ​​the first current collector 106 is too large, the area of ​​the second current collector will be too small, resulting in reduced current collecting capacity and easy ablation of the second current collector. If the area of ​​the first current collector 106 is too small, the current collecting capacity will also be reduced, and the first current collector 106 will also be easily ablated.

[0048] See also Figure 3 and Figure 4 The end plate 107 is formed with a groove 113 whose opening faces the electrode assembly 105, and the heat conducting portion 110 is disposed in the groove 113. During the actual installation process, the heat conducting portion 110 is first snapped into the groove 113, and then the heat conducting portion 110 is welded to the bottom of the groove 113. It should be noted that in this embodiment, the groove 113 serves two purposes: one is to pre-fix the heat conducting portion 110 and the groove 113 to facilitate welding; the other is that the purpose of providing the groove 113 is to reduce the thickness of the end plate 107 of the housing 104, so that heat can be transferred to the first cooling plate 102 as quickly as possible to achieve heat exchange.

[0049] Furthermore, the specific shape of the groove 113 is not limited, as long as it can achieve pre-fixation. In one embodiment, the groove 113 has a bottom wall 114 and an inner wall 115, and the inner wall 115 is arranged perpendicular to the bottom wall 114. In another embodiment, please refer to 4 and Figure 6 The groove 113 has a bottom wall 114 and an inner side wall 115 connected to the bottom wall 114. The heat-conducting portion 110 is arranged in the groove 113 and connected to the bottom wall 114. The inner side wall 115 is inclined relative to the bottom wall 114. Specifically, the inner side wall 115 has a first end close to the heat-conducting portion 110 and a second end away from the heat-conducting portion 110. In the direction from the first end to the second end, the inner side wall 115 is inclined toward the bottom wall 114. The purpose of such a setting is to facilitate welding of the heat-conducting portion 110 and the bottom wall 114.

[0050] Furthermore, in some embodiments, the angle α between the inner sidewall 115 and the bottom wall 114 is 105°≤α≤135°. When the angle between the inner sidewall 115 and the end plate 107 is greater than 135°, the groove 113 is too large, resulting in a reduced overall thickness of the end plate 107 of the housing 104 and insufficient strength of the end plate 107. When the angle between the inner sidewall 115 and the end plate 107 is less than 105°, the inner sidewall 115 has an insufficient inclination angle, making welding more difficult. Specifically, the angle between the inner side wall 115 and the bottom wall 114 can be 105°, 106°, 107°, 108°, 109°, 110°, 111°, 112°, 113°, 114°, 115°, 116°, 117°, 118°, 119°, 120°, 121°, 122°, 123°, 124°, 125°, 126°, 127°, 128°, 129°, 130°, 131°, 132°, 133°, 134°, or 135°. As a preferred embodiment, the angle between the inner side wall 115 and the bottom wall 114 is 120°, which can ensure the strength of the housing 104 and facilitate welding of the heat conducting portion 110 to the bottom wall 114.

[0051] In this embodiment, taking the end of the single battery 103 close to the first cooling plate 102 as an example, the second current collector is arranged around the first current collector 106, and the first current collector 106 is connected to the first electrode piece. Since the first current collector 106 is connected to the central area of ​​the electrode assembly 105, correspondingly, in order to facilitate welding of the first current collector 106 and the shell 104, the groove 113 is correspondingly arranged in the central area of ​​the end plate 107. For details, please refer to Figure 6 and Figure 7 The end plate 107 has a first portion and a second portion arranged around the first portion, and the groove 113 is formed on the first portion; the vertical distance between the bottom wall 114 of the groove 113 and the bottom surface 108 of the end plate 107 is H1, and the thickness of the second portion is H2, wherein H1:H2=(0.3-0.6):1. It should be noted that the wall thickness of the bottom wall 114 of the groove 113 should not be too thick or too thin. When the thickness of the bottom wall 114 of the groove 113 is too large, the thermal conductivity of the shell 104 is reduced, heat cannot be dissipated in time, and the first current collector 106 is easily burned; when the thickness of the bottom wall 114 of the groove 113 is thin, the end plate 107 of the shell 104 is locally thin, the force is uneven, and the strength is low, which is easy to be damaged, resulting in a shorter service life of the battery module 100.

[0052] In some embodiments, first electrode tabs of the same polarity are provided at both ends of the first electrode sheet, and two first current collectors 106 are respectively connected to the two first electrode tabs. Specifically, the two first current collectors 106 are respectively welded to the corresponding first electrode tabs. The first electrode tabs can be welded tabs, full tabs, or die-cut tabs.

[0053] Similarly, in some embodiments, the second electrode piece is provided with second electrode tabs of the same polarity at both ends, and two second current collectors are connected to the two second electrode tabs, respectively. Specifically, the two second current collectors are welded to the corresponding second electrode tabs. The second electrode tabs can be welded tabs, full tabs, or die-cut tabs.

[0054] See also Figure 4 and Figure 6 The first current collecting member 106 further includes a current collecting portion 116 and a connecting portion 117. The current collecting portion 116 is connected to the electrode assembly 105, and the connecting portion 117 is connected between the current collecting portion 116 and the heat conducting portion 110. The connecting portion 117 is inclined relative to the heat conducting portion 110. In this embodiment, the current collecting portion 116 is connected to the electrode assembly 105, and the connecting portion 117 is connected between the current collecting portion 116 and the heat conducting portion 110. The electrode assembly 105 transfers heat to the current collecting portion 116, and the current collecting portion 116 transfers heat to the heat conducting portion 110 through the connecting portion 117. The heat conducting portion 110 then transfers the heat to the end plate 107 of the housing 104. The end plate 107 of the housing 104 then transfers the heat to the first cooling plate 102, completing the heat exchange. More specifically, the end of the connecting portion 117 connected to the collecting portion 116 is the third end, and the end of the connecting portion 117 connected to the heat conducting portion 110 is the fourth end. In the direction from the third end to the fourth end, the connecting portion 117 is inclined toward the direction close to the heat conducting portion 110. In this way, the connecting portion 117 can cooperate with the inner side wall 115 of the groove 113, which is convenient for pre-fixing the first collecting part 106 in the groove 113.

[0055] Further, in some embodiments, see Figure 7The angle β between the connecting portion 117 and the heat conducting portion 110 is 105°≤β≤135°. Specifically, the angle between the inner side wall 115 and the bottom wall 114 can be 105°, 106°, 107°, 108°, 109°, 110°, 111°, 112°, 113°, 114°, 115°, 116°, 117°, 118°, 119°, 120°, 121°, 122°, 123°, 124°, 125°, 126°, 127°, 128°, 129°, 130°, 131°, 132°, 133°, 134°, or 135°. It should be noted that the values ​​of α and β can be set to be the same or different, and can be selected according to actual conditions. Taking into account the convenience of welding and assembly, the values ​​of α and β are generally set to be the same. More specifically, as a preferred embodiment, the angle between the inner wall 115 and the bottom wall 114 is 120°, and the angle between the connecting portion 117 and the heat conducting portion 110 is 120°. Such a setting can not only ensure the strength of the shell 104, but also the connecting portion 117 and the inner wall 115 of the groove 113 can fit more closely, which is beneficial to heat transfer and can facilitate welding of the heat conducting portion 110 and the bottom wall 114.

[0056] In some embodiments, see Figure 7 The vertical distance between the bottom wall 114 of the groove 113 and the bottom surface 108 of the end plate 107 is H1, and the thickness of the heat conducting portion 110 is H3, where H3:H1=(0.2-1.2):1. It should be noted that the wall thickness of the heat conducting portion 110 should not be too thick or too thin. In this embodiment, the first current collecting member 106 is connected to the shell 104, so the shell 104 serves as the output end of the single cell 103. Therefore, when the thickness of the heat conducting portion 110 is too large, a cold weld is likely to occur during the welding process, resulting in leakage, and the resistance of the single cell 103 increases accordingly, resulting in a large amount of energy loss during current transfer. When the thickness of the heat conducting portion 110 is relatively thin, when the temperature of the single cell 103 is too high, it is easy to burn, causing damage to the battery module 100 and shortening its service life.

[0057] In some embodiments, the side of the end plate 107 facing the first cooling plate 102 is a plane. The purpose of setting it as a plane is to facilitate heat transfer and improve cooling efficiency.

[0058] See also Figure 8The cooling device 101 further includes a cooling assembly 118, which includes a plurality of second cooling plates 119 extending from a side of the first cooling plate 102 proximate to the battery cells 103. The plurality of second cooling plates 119 are connected to the first cooling plate 102 and are thermally connected to radial sidewalls of the battery cells 103. In this embodiment, each second cooling plate 119 includes an opposing water inlet and a water outlet. During cooling, the cooling medium enters the second cooling plate 119 from the water inlet and flows out of the second cooling plate 119 from the water outlet. Furthermore, the cooling assembly 118 includes a plurality of connectors 120, one of which is provided between each two adjacent second cooling plates 119. One end of the connector 120 is connected to the water inlet of one of the second cooling plates 119, and the other end is connected to the water outlet of another second cooling plate 119. In this configuration, the plurality of second cooling plates 119 are sequentially connected via the plurality of connectors 120.

[0059] In some embodiments, the plurality of second cooling plates 119 and the plurality of connecting heads 120 are integrally formed.

[0060] Further, in this embodiment, please refer to Figure 8 In order to improve the cooling efficiency, the second cooling plate 119 is configured as a serpentine tube, the shape of which is adapted to the shape of the single battery 103, thereby increasing the contact area between the second cooling plate 119 and the single battery 103 and improving the heat dissipation capacity.

[0061] It should be noted that, in this embodiment, the cooling device 101 cools the plurality of single cells 103 in the axial direction through the first cooling plate 102, and cools the single cells 103 in the radial direction through the plurality of second cooling plates 119. The first cooling plate 102 and the second cooling plate 119 cooperate with each other to improve the cooling efficiency. With such an arrangement, the upper end of the battery module 100 (which can be in contact with the air and dissipate heat by itself), the lower end of the battery module 100 (dissipates heat through the first cooling plate 102), and the middle part of the battery module 100 (dissipates heat through the second cooling plate 119), the combination of multiple heat dissipation methods can better control the temperature of the battery module 100 and avoid thermal runaway.

[0062] Furthermore, the cooling device 101 also includes a third cooling plate 121, one end of the third cooling plate 121 is connected to the cooling component 118, and the other end is connected to the first cooling plate 102, thereby forming a cooling circuit. In this embodiment, the water inlet of the cooling device 101 is arranged on the cooling component 118, and the water outlet of the cooling device 101 is arranged on the first cooling plate 102. During the cooling process, the cooling medium enters the cooling component 118 from the water inlet, and then flows from the cooling component 118 to the third cooling plate 121, flows from the third cooling plate 121 to the first cooling plate 102, and flows out from the water outlet on the first cooling plate 102 to complete the heat exchange.

[0063] It should be noted that the connection method between the first current collecting member 106 and the end plate 107 is not limited. In one embodiment, the first current collecting member 106 abuts the end plate 107; in another embodiment, the first current collecting member 106 and the end plate 107 are welded. It should be noted that the thermal conductivity of the single cell 103 in the axial direction is more than 200 times that in the radial direction. In this embodiment, by connecting the first current collecting member 106 to the end plate 107, the negative electrode of the single cell 103 is directly connected to the housing 104. The end plate 107 of the single cell 103 serves as a heat-conducting component. First cooling plates 102 are provided at the axial ends of the plurality of single cells 103 to achieve axial heat dissipation of the single cells 103, thereby better controlling the temperature of the battery module 100 and enabling the battery module to perform fast charging or fast discharging operations such as high-rate discharge without thermal runaway.

[0064] In some embodiments, the weld area between the first current collector 106 and the end plate 107 is S3, where S3:S2 = (0.01-0.05):1. It should be noted that when S3 / S2 is less than 0.01, the weld area between the first current collector 106 and the end plate 107 is small, and the first current collector 106 and the end plate 107 are not tightly attached, resulting in reduced thermal conductivity of the single battery 103. When S3 / S2 is greater than 0.05, the weld area between the first current collector 106 and the end plate 107 increases, making welding more difficult and potentially affecting the second current collector during welding.

[0065] The present invention also provides a battery pack comprising the aforementioned battery module 100. The specific structure of the battery module 100 is similar to that of the aforementioned embodiments. Since the present battery pack utilizes all of the technical solutions of all of the aforementioned embodiments, it at least possesses all of the beneficial effects brought about by the technical solutions of the aforementioned embodiments, and therefore, no further details will be given here.

[0066] The technical solution of the present invention is further described in detail below in conjunction with specific examples and data. It should be understood that the following examples are only used to explain the present invention and are not used to limit the present invention.

[0067] It should be noted that the following embodiments are all tested using a single cell as an example, with the entire battery pack operating and one of the single cells as the benchmark for testing. The parameters of the single cell include S1, S2, H1, H2, H3, and S3.

[0068] Test plan: such as Figure 9 As shown, the central hole in the middle area of ​​the single battery is used as the temperature test point T, and the temperature there is collected to determine the heat conduction and heat dissipation capabilities of the first current collecting member.

[0069] Test method:

[0070] 1. Use CCCV charging mode to charge the battery pack at a charging current of 0.5C. When the voltage of the battery pack reaches 4.25V, use 4.25V constant voltage charging. When the charging current drops to 0.02C, stop charging the battery and rest for 10 minutes.

[0071] 2. Discharge the battery pack with a charging current of 3.0C until the temperature of the temperature test point of the battery pack reaches 80°C; then rest at 35°C for 30 minutes until the temperature of the temperature test point of the battery pack reaches 35°C;

[0072] 3. Repeat step 2 until the SOC reaches 10% and detect the maximum temperature inside the battery pack.

[0073] A basic group 1, a control group 1 and a control group 2 were set up. The parameters of the basic group 1, the control group 1 and the control group 2 were exactly the same. Among them, the control group 1 was not provided with a first cooling plate, and the end plate of the shell of the control group 2 was not provided with a groove. The specific test results are shown in Table 1.

[0074] Table 1 Test results of basic group 1, control group 1 and control group 2

[0075] <![CDATA[S1 / mm 2 ]]> <![CDATA[S2 / mm 2 ]]> <![CDATA[S3 / mm 2 ]]> H1 / mm H2 / mm H3 / mm Maximum temperature / ℃ Basic Group 1 315 1451.4 28.26 0.35 0.7 0.15 55 Control group 1 315 1451.4 28.26 0.35 0.7 0.15 68 Control group 2 315 1451.4 28.26 / 0.7 0.15 60

[0076] According to the verification results in Table 1, the battery pack of basic group 1 is provided with a first cooling plate, and the temperature inside the battery pack is lower than that of control group 1. The end plate of the shell of the single battery of basic group 1 is provided with a groove, and the temperature of the battery pack is lower than that of control group 2. In summary, the battery pack provided in this application has a high cooling efficiency and can be used in fast charging and discharging occasions such as high-rate discharge.

[0077] Taking basic group 1 as the parameter standard, changing S1 and S2, the specific test results are shown in Table 2.

[0078] Table 2 Test results of Examples 1-4 and Comparative Examples 1-2

[0079]

[0080] According to the verification results in Table 2, it can be seen that: the area of ​​the first heat-conducting surface of Example 1 is smaller than the area of ​​the first heat-conducting surface of Example 2, and the temperature of the battery pack of Example 2 is lower than the temperature of the battery pack of Example 1; the welding area of ​​Example 3 is smaller than the welding area of ​​Example 4, and the temperature of the battery pack of Example 4 is lower than the temperature of the battery pack of Example 3; the area of ​​the first heat-conducting surface of Comparative Example 1 is smaller than the areas of the first heat-conducting surfaces of Examples 1 and 2, and the temperature of the battery pack of Comparative Example 1 is higher than the temperatures of the battery packs of Examples 1 and 2; the welding area of ​​Comparative Example 2 is smaller than the areas of the welding surfaces of Examples 3 and 4, and therefore the temperature of the battery pack of Comparative Example 2 is higher than the temperatures of the battery packs of Examples 3 and 4.

[0081] Taking basic group 1 as the parameter standard, H1, H2 and H3 are changed. The specific test results are shown in Table 3.

[0082] Table 3 Test results of Examples 5-8 and Comparative Examples 3-4

[0083]

[0084]

[0085] The verification results in Table 3 show that: in Comparative Example 3, the ratio of H1 to H2 is greater than 0.6. Compared with Examples 5 and 6, the temperature of the battery pack in Comparative Example 3 is significantly higher than that of the battery packs provided in Examples 5 and 6. In Comparative Example 4, the ratio of H3 to H1 is greater than 1.2. The thickness of the bottom wall of the heat conduction portion and the groove is relatively thick, resulting in a cold weld during the welding process. Liquid leakage occurs during the actual test, and the battery pack provided in Comparative Example 4 cannot be used normally.

[0086] The above is a detailed introduction to the embodiments of the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, based on the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A battery module, characterized in that: include: a cooling device comprising a first cooling plate; and A plurality of single cells, each of the single cells comprising a housing, an electrode assembly, and two first current collectors, the housing having an end plate, the electrode assembly being disposed within the housing, and the electrode assembly comprising a first electrode sheet; Among them, the two first current collecting parts are located at both ends of the electrode assembly along the axial direction and are electrically connected to the first pole piece. The first current collecting part close to the end plate includes a heat conducting part, and the heat conducting part is connected to the side of the end plate close to the electrode assembly. The side of the end plate facing away from the electrode assembly is connected to the first cooling plate.

2. The battery module according to claim 1, wherein: The heat-conducting portion includes a first heat-conducting surface facing the end plate, the first heat-conducting surface is connected to the end plate, the end plate includes a second heat-conducting surface facing the first cooling plate, the second heat-conducting surface is connected to the first cooling plate, the area of ​​the first heat-conducting surface is S1, and the area of ​​the second heat-conducting surface is S2, wherein S1:S2=(0.05~0.25):

1.

3. The battery module according to claim 1 or 2, characterized in that: The end plate is formed with a groove opening toward the electrode assembly. The groove has a bottom wall and an inner side wall connected to the bottom wall. The heat conducting portion is disposed in the groove and connected to the bottom wall.

4. The battery module according to claim 3, characterized in that: The inner side wall is inclined relative to the bottom wall, and an included angle between the inner side wall and the bottom wall is α, wherein 105°≤α≤135°.

5. The battery module according to claim 3, wherein: The end plate has a first portion and a second portion disposed around the first portion, and the groove is formed on the first portion; A vertical distance between the bottom wall and a side surface of the end plate facing away from the electrode assembly is H1, and a thickness of the second portion is H2, wherein H1:H2=(0.3-0.6):

1.

6. The battery module according to claim 1 or 2, characterized in that: Two ends of the first pole piece are provided with first pole tabs of the same polarity, and the two first current collecting members are respectively connected to the two first pole tabs.

7. The battery module according to claim 1 or 2, characterized in that: The first current collecting member further includes a current collecting portion and a connecting portion, wherein the current collecting portion is connected to the electrode assembly, the connecting portion is connected between the current collecting portion and the heat conducting portion, and the connecting portion is inclined relative to the heat conducting portion.

8. The battery module according to claim 7, characterized in that: An included angle between the connecting portion and the heat conducting portion is β, wherein 105°≤β≤135°.

9. The battery module according to claim 3, characterized in that: The vertical distance between the bottom wall of the groove and the side surface of the end plate facing away from the electrode assembly is H1, and the thickness of the heat conducting portion is H3, wherein H3:H1=(0.2-1.2):

1.

10. The battery module according to claim 1 or 2, characterized in that: The side surface of the end plate facing the first cooling plate is a plane.

11. The battery module according to claim 1 or 2, characterized in that: The cooling device also includes a cooling assembly, which includes a plurality of second cooling plates extending from the first cooling plate on a side close to the single battery. The plurality of second cooling plates are connected to the first cooling plate, and the second cooling plates are thermally connected to the radial side walls of the single battery.

12. The battery module according to claim 2, wherein: The first current collecting member is welded to the end plate.

13. The battery module according to claim 12, characterized in that: The welding area between the first current collecting member and the end plate is S3, wherein S3:S2=(0.01-0.05):

1.

14. A battery pack, characterized in that: Comprising the battery module according to any one of claims 1 to 13.

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