Battery pack

Abstract

The utility model discloses a battery pack and equipment. The battery pack comprises a shell, a battery cell assembly, a first heat dissipation piece and a second heat dissipation piece, the shell is provided with an accommodating space; the battery cell assembly comprises a plurality of stacked battery cells, and the battery cell assembly is arranged in the accommodating space; the plurality of first heat dissipation pieces and the plurality of battery cells are arranged in a one-to-one correspondence manner, each first heat dissipation piece comprises a main body section and a first bending section, the main body section is arranged on the first side surface of the battery cell, and the first bending section is connected to the main body section and is arranged on the second side surface, adjacent to the first side surface, of the battery cell; the second heat dissipation piece is arranged on the side, away from the battery cell assembly, of the first bent section and comprises a heat absorption layer and a heat conduction layer, and the heat conduction layer wraps the heat absorption layer. The problems that in the charging and discharging process of a lithium battery in the prior art, the heat dissipation effect of the lithium battery is poor, the temperature of the lithium battery is easily increased, and the temperature difference between battery cells is large can be solved.

Description

Technical Field

[0001] The present application relates to the technical field of lithium batteries, and in particular to a battery pack. Background Art

[0002] With the development of fast charge and discharge technology, in order to meet the performance requirements of lithium batteries, lithium batteries are often charged and discharged at a high rate, which can easily lead to high temperatures in the battery cells. Since the performance and cycle life of lithium batteries are closely related to the temperature of the battery cells, if lithium batteries are exposed to high temperatures for a long time, the degradation of the battery electrodes and the decomposition of the electrolyte will be accelerated, which can easily cause irreversible damage to the internal structure of the battery, thereby affecting the performance of the lithium battery. In extreme cases, the lithium battery may even experience thermal runaway and cause safety accidents. In addition, as the number of battery cells connected in series and parallel increases, the temperature difference between the battery cells also increases, and the large temperature difference will cause inconsistent battery life, ultimately resulting in a reduction in the life of the battery pack.

[0003] Lithium batteries are limited by weight and volume requirements, and their heat dissipation is less considered, especially consumer lithium batteries, such as drone lithium batteries, which are extremely sensitive to weight. However, with the rapid development of drones, the discharge rate of mainstream consumer drone lithium batteries has now exceeded 4C. The temperature of lithium batteries can easily exceed the maximum allowable temperature limit, resulting in an increase in the temperature difference between the cells. If the temperature of the lithium battery is not reduced, it is easy to cause the drone's battery to not be completely discharged and the cruising range to be shortened.

[0004] At present, most of the heat dissipation of batteries is based on natural cooling, forced air cooling and liquid cooling. For example, water cooling and air cooling used in automotive power battery cooling have good heat dissipation effects, but they occupy a large volume and have many parts, and cannot be directly applied to lithium batteries with weight and volume restrictions, such as drone lithium batteries. Therefore, how to keep the existing consumer lithium battery structure basically unchanged and the weight increase slightly to reduce the temperature of lithium batteries and reduce the temperature difference between battery cells is a difficult problem. Utility Model Content

[0005] The main purpose of the present application is to provide a battery pack to solve the problem in the prior art that the heat dissipation effect of the lithium battery is poor during the charging and discharging process of the lithium battery, which easily leads to the temperature rise of the lithium battery and the large temperature difference between the battery cells.

[0006] According to one aspect of the present application, a battery pack is provided, comprising:

[0007] A housing having a receiving space;

[0008] A battery cell assembly, comprising a plurality of stacked battery cells, wherein the battery cell assembly is arranged in the accommodating space;

[0009] a first heat sink, wherein a plurality of the first heat sinks are arranged in one-to-one correspondence with the plurality of the battery cells, the first heat sink comprising a main body section and a first bending section, the main body section being arranged on a first side surface of the battery cell, the first bending section being connected to the main body section and being arranged on a second side surface of the battery cell adjacent to the first side surface;

[0010] The second heat sink is arranged on a side of the first bending section away from the battery core assembly, and the second heat sink comprises a heat absorption layer and a heat conduction layer, wherein the heat conduction layer covers the heat absorption layer.

[0011] Furthermore, the heat absorption layer includes a first phase change sheet, and the heat conduction layer includes a graphite sheet.

[0012] Furthermore, the second heat sink also includes a first foam layer, and along a first direction, the heat absorption layer, the first foam layer and the heat conduction layer are stacked in sequence, and the heat conduction layer covers the heat absorption layer and the first foam layer.

[0013] Further, along the first direction, the thickness T1 of the heat absorption layer satisfies the relationship: T1>1mm; and / or,

[0014] Along the first direction, the thickness T2 of the first foam layer satisfies the relationship: 0.5 mm ≤ T2 ≤ 1.5 mm; and / or,

[0015] Along the first direction, the thickness T3 of the heat conducting layer satisfies the relationship: T3 ≥ 0.04 mm.

[0016] Further, when the discharge rate of the battery cell is less than 4C, the thickness T1 of the heat absorption layer satisfies the relationship: 1mm<T1<2mm; and / or,

[0017] When the discharge rate of the battery cell is greater than 4C, the thickness T1 of the heat absorption layer satisfies the relationship: 2mm<T1<3mm.

[0018] Furthermore, the battery pack also includes a third heat sink, which is arranged on a third side of the battery cell adjacent to the first side. The third heat sink includes a second phase change sheet and a second foam layer. Along the second direction, the second phase change sheet and the second foam layer are stacked in sequence.

[0019] Furthermore, the first heat sink also includes a second bending section, the second bending section is connected to the main section and is arranged on the third side surface, and the third heat sink is arranged on a side of the second bending section away from the battery cell assembly.

[0020] Further, along the third direction, the thickness T4 of the first heat sink satisfies the relationship: T4 ≥ 0.15 mm; and / or,

[0021] Along the third direction, the width D1 of the first bending section and the width D2 of the battery cell satisfy the relationship: 0.5D2≤D1≤D2; and / or,

[0022] Along the third direction, the width D3 of the second bending section and the width D2 of the battery cell satisfy the relationship: 0.5D2≤D3≤D2.

[0023] Furthermore, the main body segment is provided with a through hole, and the through holes include a plurality of through holes, and the sum of the projection areas S1 of the plurality of through holes along the third direction on the first side surface and the surface area S2 of the main body segment satisfy the relationship: S1 / S2<0.3.

[0024] Furthermore, the battery pack further comprises a fixing belt, wherein the fixing belt is sleeved on the outer periphery of the battery core assembly and the first heat sink; and / or,

[0025] The battery pack further includes a third foam layer, and the third foam layer is arranged between every two adjacent battery cells.

[0026] In the present application, relative to the structure of the battery pack in the prior art, the present application places the first heat sink in close contact with the first side and the second side of the battery cell, and places the second heat sink in close contact with the side of the first bending section away from the battery cell assembly. Since the first heat sink and the second heat sink have high thermal conductivity, when the battery pack starts working, the first heat sink and the second heat sink can quickly diffuse the heat generated by the battery cell assembly, effectively enhancing the heat exchange between the battery cells, thereby reducing the temperature difference between the battery cells, and then reducing the overall temperature of the battery cell assembly, and then reducing the temperature inside the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0028] Figure 1 It is a schematic diagram of the explosion structure of the battery pack disclosed in the embodiment of the present application;

[0029] Figure 2 It is a schematic diagram of the structure of the battery core assembly, the first heat sink, the second heat sink and the third heat sink disclosed in the embodiment of the present application;

[0030] Figure 3 A schematic diagram of the structure of a first heat sink disclosed in an embodiment of the present application;

[0031] Figure 4 A schematic diagram of the structure of a second heat sink disclosed in an embodiment of the present application;

[0032] Figure 5 The embodiment disclosed in this application Figure 4 A magnified schematic diagram of the middle A area;

[0033] Figure 6 It is a schematic diagram of the structure explosion of the second heat sink disclosed in the embodiment of the present application;

[0034] Figure 7 It is a schematic diagram of the explosion structure of the third heat sink disclosed in the embodiment of the present application;

[0035] Figure 8 This is a temperature comparison chart of the control group disclosed in the embodiments of the present application and the battery pack of the present application.

[0036] The above drawings include the following reference numerals:

[0037] 10. Shell; 20. Battery cell assembly; 21. Battery cell; 211. First side; 212. Second side; 213. Third side; 31. First heat sink; 311. Main body section; 3111. Through hole; 312. First bending section; 32. Second heat sink; 321. Heat absorption layer; 322. First foam layer; 323. Heat conductive layer; 33. Third heat sink; 331. Second phase change sheet; 332. Second foam layer; 40. Fixing tape; 50. Third foam layer; 60. Battery management system; 70. Double-sided tape. DETAILED DESCRIPTION

[0038] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0039] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0040] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0041] It should be noted that the first direction in this application is the attached Figure 1 The direction indicated by the letter X in the figure is the height direction of the battery pack, and the second direction is the Figure 1 The direction indicated by letter Y is the length direction of the battery pack, and the third direction is the Figure 1 The direction indicated by the letter Z (i.e., the width direction of the battery pack), wherein the first direction, the second direction, and the third direction are perpendicular to each other.

[0042] See also Figures 1 to 8 As shown, the present application provides a battery pack, which includes a housing 10, a battery cell assembly 20, a first heat sink 31 and a second heat sink 32.

[0043] The housing 10 has an accommodating space (not shown in the drawings); the battery cell assembly 20 includes a plurality of stacked battery cells 21, and the battery cell assembly 20 is arranged in the accommodating space; a plurality of first heat sinks 31 are arranged one-to-one with the plurality of battery cells 21, the first heat sink 31 includes a main body section 311 and a first bending section 312, the main body section 311 is arranged on the first side surface 211 of the battery cell 21, the first bending section 312 is connected to the main body section 311, and is arranged on the second side surface 212 of the battery cell 21 adjacent to the first side surface 211, the second heat sink 32 is arranged on the side of the first bending section 312 away from the battery cell assembly 20, the second heat sink 32 includes a heat absorption layer 321 and a heat conductive layer 323, and the heat conductive layer 323 covers the heat absorption layer 321.

[0044] In this embodiment, when the battery pack is actually processed, multiple battery cells 21 can be stacked in sequence (i.e., arranged in sequence along the width direction of the battery pack), and then each first heat sink 31 is closely attached to each battery cell 21, so that each main section 311 is attached to the first side surface 211 of each battery cell 21, and each first bending section 312 is attached to the second side surface 212 of each battery cell 21, and then the second heat sink 32 is closely attached to the side of the first bending section 312 away from the battery cell assembly 20. At this time, the second heat sink 32 completely covers the multiple first bending sections 312. After the assembly is completed, the battery cell assembly 20 with the first heat sink 31 and the second heat sink 32 is installed in the accommodation space to form a battery pack.

[0045] That is to say, when the battery pack is actually used, since the battery cell assembly 20 generates a large amount of heat during operation, which causes the temperature inside the battery pack to rise, therefore, in this embodiment, a plurality of first heat sinks 31 are closely attached to a plurality of battery cells 21 in a one-to-one correspondence, and a second heat sink 32 is attached to the side of the first bending section 312 away from the battery cell assembly 20. In this way, the first heat sink 31 can absorb the heat generated by the battery cell 21, and conduct the heat to the second heat sink 32 through the first bending section 312. The second heat sink 32 can absorb the heat through the heat absorption layer 321, and evenly distribute the heat inside the battery pack through the heat conductive layer 323, thereby reducing the temperature of the battery cell assembly 20, and then reducing the temperature inside the battery pack, thereby extending the service life of the battery pack to a certain extent. In addition, the first heat sink 31, the second heat sink 32 and the battery cell assembly 20 of this embodiment are all arranged inside the shell 10, so that the existence of the shell 10 can protect the first heat sink 31, the second heat sink 32 and the battery cell assembly 20.

[0046] Compared with the structure of the battery pack in the prior art, in this embodiment, the first heat sink 31 is closely attached to the first side surface 211 and the second side surface 212 of the battery cell 21, and the second heat sink 32 is closely disposed on the side of the first bending section 312 away from the battery cell assembly 20. Since the first heat sink 31 and the second heat sink 32 have high thermal conductivity, when the battery pack starts working, the first heat sink 31 and the second heat sink 32 can quickly diffuse the heat generated by the battery cell assembly 20, effectively enhancing the heat exchange between the battery cells 21, thereby reducing the temperature difference between the battery cells 21, and then reducing the overall temperature of the battery cell assembly 20, and further reducing the temperature inside the battery pack.

[0047] It should be noted that the heat-conducting layer 323 covering the heat-absorbing layer 321 in the present application means that the heat-conducting layer 323 at least covers two relatively large surfaces of the heat-absorbing layer 321. Of course, in other embodiments of the present application, the heat-conducting layer 323 may also cover other surfaces of the heat-absorbing layer 321, or even completely cover all surfaces of the heat-absorbing layer 321. Figure 5 The figure shows a situation where the heat conductive layer 323 completely covers all surfaces of the heat absorbing layer 321 .

[0048] It is understandable that the battery cell 21 in this embodiment may include two, three or more than three cells, which may be designed according to actual processing requirements. Figure 1 The case where the number of battery cells 21 is four is shown.

[0049] Specifically, the battery cell 21 in this embodiment is in the shape of a rectangular parallelepiped, and the largest faces of adjacent battery cells 21 are arranged opposite to each other. That is to say, in this embodiment, the side with the largest area of ​​the battery cell 21 is defined as the first side face 211 of the battery cell 21, and the main section 311 of the first heat sink 31 is attached to the first side face 211 of the battery cell 21; along the first direction (i.e., along the height direction of the battery pack), in this embodiment, the upper and lower side faces adjacent to the first side face 211 of the battery cell 21 are defined as the second side face 212 of the battery cell 21, and the first bending section 312 is attached to the second side face 212; along the second direction (i.e., along the length direction of the battery pack), in this embodiment, the rear side face adjacent to the first side face 211 of the battery cell 21 (i.e., the side of the battery cell 21 away from the battery management system 60) is defined as the third side face 213 of the battery cell 21, and the second bending section is attached to the third side face 213.

[0050] Specifically, the heat absorption layer 321 in this embodiment includes a first phase change sheet, and the heat conduction layer 323 includes a graphite sheet. The first phase change sheet is made of phase change material, and the first phase change sheet and the graphite sheet function to absorb heat, distribute heat evenly, and store heat.

[0051] Further, see Figures 4 to 6 As shown, in the embodiment shown in the present application, the second heat sink 32 also includes a first foam layer 322, and along the first direction, the heat absorption layer 321, the first foam layer 322 and the heat conduction layer 323 are stacked in sequence, and the heat conduction layer 323 covers the heat absorption layer 321 and the first foam layer 322. That is to say, in this embodiment, the first phase change sheet is arranged close to the first bending section 312, and the first foam layer 322 is arranged between the first phase change sheet and the graphite sheet. It can be understood that, due to the compressibility of the foam, when the battery cell assembly 20, the first heat sink 31 and the second heat sink 32 are installed in the accommodating space, the presence of the first foam layer 322 can make the second heat sink 32 fit closely with the inner wall surface of the housing 10, so that the heat absorbed by the second heat sink 32 is quickly conducted to the housing 10.

[0052] It should be noted that in the present application, the heat-conducting layer 323 covers the heat-absorbing layer 321 and the first foam layer 322, which means that the heat-conducting layer 323 at least covers the larger surface of the heat-absorbing layer 321 and the first foam layer 322. Of course, in other embodiments of the present application, the heat-conducting layer 323 may also cover other surfaces of the heat-absorbing layer 321 and the first foam layer 322, and may even completely cover all surfaces of the heat-absorbing layer 321 and the first foam layer 322. Figure 5 The figure shows a situation where the heat-conducting layer 323 completely covers all surfaces of the heat-absorbing layer 321 and the first foam layer 322 .

[0053] Further, in an embodiment not shown in the present application, along the first direction, the heat absorption layer 321, the first foam layer 322 and the heat conduction layer 323 are stacked in sequence, and the heat conduction layer 323 does not cover the heat absorption layer 321 and the first foam layer 322. Such a configuration has a simple structure and is easy to manufacture. Among them, the heat conduction layer 323 does not cover the heat absorption layer 321 and the first foam layer 322 means that the heat conduction layer 323 only covers the larger surface of the heat absorption layer 321 and the first foam layer 322, and does not cover the smaller side surface of the heat absorption layer 321 and the first foam layer 322. Specifically, after the second heat sink 32 absorbs heat, the graphite sheet therein has a high planar thermal conductivity, which can quickly conduct heat to various positions of the second heat sink 32, so that the second heat sink 32 has a good heat distribution performance; the first phase change sheet has a phase change characteristic, and compared with other materials, it has stronger heat absorption and heat storage performance. After absorbing heat, the first phase change sheet can change the shape of the material and store the heat, while the temperature of the material remains unchanged, so that the second heat sink 32 can effectively absorb heat and ensure that its own temperature does not change significantly, so that the temperature of the battery cell assembly 20 is kept within the normal operating temperature range. Moreover, the first phase change sheet changes shape after absorbing heat, which can store heat. In a cold environment, it changes shape again and releases heat, which plays a role in keeping the battery cell assembly 20 warm.

[0054] Alternatively, see Figure 6 As shown, along the first direction, the thickness T1 of the heat absorption layer 321 in this embodiment satisfies the relationship: T1>1mm, for example, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2mm. When the thickness of the heat absorption layer 321 (i.e., the first phase change sheet) is less than 1mm, the heat absorption layer 321 has weaker heat absorption and heat storage performance; when the thickness of the heat absorption layer 321 (i.e., the first phase change sheet) is greater than 1mm, the heat absorption layer 321 has stronger heat absorption and heat storage performance. However, the thickness of the heat absorption layer 321 is not easy to be too thick. Excessive thickness increases the weight of the second heat sink 32, thereby increasing the overall weight of the battery pack.

[0055] Alternatively, see Figure 6As shown, along the first direction, the thickness T2 of the first foam layer 322 in this embodiment satisfies the relationship: 0.5mm≤T2≤1.5mm, for example 0.5mm, 0.7mm, 0.9mm, 1.1mm, 1.3mm, 1.5mm. The first foam layer 322 has a certain elasticity, can be deformed by being squeezed, and the raw materials are simple and easy to obtain. When the thickness of the first foam layer 322 is less than 0.5mm, it is easy to cause the second heat sink 32 to not fit tightly with the inner wall surface of the outer shell 10, so that the heat cannot be quickly conducted out; when the thickness of the first foam layer 322 is greater than 1.5mm, the weight of the second heat sink 32 is increased, thereby increasing the overall weight of the battery pack.

[0056] Alternatively, see Figure 6 As shown, along the first direction, the thickness T3 of the thermal conductive layer 323 in this embodiment satisfies the relationship: T3 ≥ 0.04 mm, for example 0.04 mm, 0.06 mm, 0.08 mm, 0.1 mm. The thickness of the thermal conductive layer 323 is small, and the heat transfer resistance is low, so that the heat generated by the battery cell assembly 20 can be quickly transferred to the second heat sink 32.

[0057] It is understandable that the thicknesses of the first phase change sheet, the first foam layer 322 and the graphite sheet can be selected according to the size and heat generation of the battery cell assembly 20 .

[0058] Specifically, see Figure 6 As shown, in this embodiment, double-sided adhesive tape 70 is provided on one side of the first phase change sheet close to the battery core assembly 20 and between the first phase change sheet and the first foam layer 322. The double-sided adhesive tape 70 fixes the first phase change sheet and the first foam layer 322 to each other and makes the second heat sink 32 closely attached to the plurality of first bending sections 312. Specifically, the double-sided adhesive tape 70 is a heat-conducting double-sided adhesive tape.

[0059] Further, in this embodiment, when the discharge rate of the battery cell 21 is less than 4C, the thickness T1 of the heat absorption layer 321 satisfies the relationship: 1mm<T1<2mm, for example, 1.2mm, 1.4mm, 1.6mm, 1.8mm; and / or, when the discharge rate of the battery cell 21 is greater than 4C, the thickness T2 of the heat absorption layer 321 satisfies the relationship: 2mm<T1<3mm, for example, 2.2mm, 2.4mm, 2.6mm, 2.8mm. That is to say, in this embodiment, the thickness of the heat absorption layer 321 can be selected according to different discharge rates. In this way, not only the second heat sink 32 has a higher heat transfer and heat dissipation effect, thereby reducing the temperature inside the battery pack and extending the service life of the battery pack to a certain extent, but also the weight of the second heat sink 32 is increased as little as possible, thereby reducing the overall weight of the battery pack, which is conducive to the lightweight design of the battery pack.

[0060] Further, see Figure 1as well as Figure 7 As shown, the battery pack in this embodiment also includes a third heat sink 33, which is arranged on the third side 213 of the battery cell 21 adjacent to the first side 211. The third heat sink 33 includes a second phase change sheet 331 and a second foam layer 332. Along the second direction, the second phase change sheet 331 and the second foam layer 332 are stacked in sequence. That is to say, the second phase change sheet 331 is arranged close to the battery cell assembly 20. Specifically, the second phase change sheet 331 has the same structure as the first phase change sheet, so the two have the same effect; the second foam layer 332 has the same structure as the first foam layer 322, so the two have the same effect. In this embodiment, on the basis of the existence of the first heat sink 31 and the second heat sink 32, a third heat sink 33 is added. The third heat sink 33 can further absorb the heat generated by the battery cell assembly 20, thereby reducing the temperature of the battery cell assembly 20, and then reducing the temperature inside the battery pack.

[0061] Specifically, see Figure 7 As shown, in this embodiment, double-sided adhesive tape 70 is provided on one side of the second phase change sheet 331 close to the battery cell assembly 20 and between the second phase change sheet 331 and the second foam layer 332. The existence of the double-sided adhesive tape 70 fixes the second phase change sheet 331 and the second foam layer 332 to each other and makes the third heat sink 33 closely attached to the battery cell assembly 20. Specifically, the double-sided adhesive tape 70 is a heat-conducting double-sided adhesive tape.

[0062] Furthermore, in an embodiment not shown in the present application, the first heat sink 31 further includes a second bending section, the second bending section is connected to the main section 311 and is arranged on the third side 213, and the third heat sink 33 is arranged on the side of the second bending section away from the battery cell assembly 20. In this arrangement, when the battery cell assembly 20 generates heat, the first heat sink 31 can absorb the heat and quickly conduct it to the third heat sink 33 through the second bending section. The third heat sink 33 can quickly diffuse the heat generated by the battery cell assembly 20, effectively strengthening the heat exchange between the battery cells 21, thereby reducing the temperature difference between the battery cells 21, and then reducing the overall temperature of the battery cell assembly 20, and then reducing the temperature inside the battery pack.

[0063] Furthermore, the first heat sink 31 in this embodiment can be made of aluminum alloy, 5-series aluminum, 6-series aluminum and other materials, which are not specifically limited in this application, as long as the first heat sink 31 can have high thermal conductivity.

[0064] Specifically, the first heat sink 31 and the battery core 21 in this embodiment are connected by a double-sided adhesive tape 70, so that the two are fixed to each other. Specifically, the double-sided adhesive tape 70 is a heat-conducting double-sided adhesive tape.

[0065] Alternatively, see Figure 1As shown, along the third direction, the thickness T4 of the first heat sink 31 in this embodiment satisfies the relationship: T4 ≥ 0.15 mm, such as 0.15 mm, 0.17 mm, 0.19 mm. When the thickness of the first heat sink 31 is less than 0.15 mm, the first heat sink 31 has a weaker thermal conductivity, which is not conducive to absorbing the heat generated by the battery cell assembly 20; when the thickness of the first heat sink 31 is greater than or equal to 0.15 mm, the first heat sink 31 has a higher thermal conductivity, and can quickly absorb the heat generated by the battery cell assembly 20, and conduct the heat to the second heat sink 32 and the third heat sink 33.

[0066] Alternatively, see Figure 1 As shown, along the third direction, the width D1 of the first bending section 312 in this embodiment and the width D2 of the battery cell 21 satisfy the relationship: 0.5D2≤D1≤D2. Since the first bending section 312 is attached to the second side surface 212 of the battery cell 21, the first bending section 312 can further improve the thermal conductivity of the first heat sink 31 on the basis of the existence of the main section 311. At the same time, the existence of the first bending section 312 is conducive to the bonding of the second heat sink 32, improves the bonding strength of the second heat sink 32, and the first bending section 312 in this embodiment can quickly conduct the heat generated by the battery cell 21 to the second heat sink 32, thereby reducing the temperature of the battery cell assembly 20, and then reducing the temperature inside the battery pack, thereby extending the service life of the battery pack.

[0067] Optionally, along the third direction, the width D3 of the second bending section in this embodiment and the width D2 of the battery cell 21 satisfy the relationship: 0.5D2≤D3≤D2 (D3 is not shown in the accompanying drawings). Since the second bending section is attached to the third side surface 213 of the battery cell 21, the second bending section can further improve the thermal conductivity of the first heat sink 31 on the basis of the existence of the main section 311 and the first bending section 312. At the same time, the existence of the second bending section is conducive to the bonding of the third heat sink 33, improves the bonding strength of the third heat sink 33, and the second bending section in this embodiment can quickly conduct the heat generated by the battery cell 21 to the third heat sink 33, thereby reducing the temperature of the battery cell assembly 20, and then reducing the temperature inside the battery pack, thereby extending the service life of the battery pack.

[0068] Furthermore, in this embodiment, a through hole 3111 is provided on the main section 311, and the through hole 3111 includes a plurality of through holes, and the sum S1 of the projection areas of the plurality of through holes 3111 on the first side surface 211 along the third direction and the surface area S2 of the main section 311 satisfy the relationship: S1 / S2<0.3, for example, 0.1, 0.15, 0.2, 0.25. Such a configuration can not only ensure the heat conduction effect of the first heat sink 31, but also reduce the weight of the first heat sink 31 to a certain extent, thereby reducing the overall weight of the battery pack. It should be noted that the surface area of ​​the main section 311 is the surface area of ​​the largest surface of the main section 311.

[0069] Specifically, the through hole 3111 in the present application can be a circular through hole, a square through hole, a hexagonal through hole, a waist-shaped through hole, etc. Figure 3 The case where the through hole 3111 is a waist-shaped through hole is shown.

[0070] Optionally, the number of through holes 3111 in the present application may be two, four, six, eight, ten or more, and is not specifically limited in the present application, as long as the sum of the projection areas S1 of the plurality of through holes 3111 along the third direction on the first side surface 211 and the surface area S2 of the main body segment 311 satisfy S1 / S2<0.3. Figure 3 The case where the number of through holes 3111 is ten is shown.

[0071] Optionally, the present application does not make any specific limitation on the arrangement of the through holes 3111, as long as it can be ensured that the sum of the projection areas S1 of the plurality of through holes 3111 along the third direction on the first side surface 211 and the surface area S2 of the main body section 311 satisfy S1 / S2<0.3, the appendix of this embodiment Figure 3 The diagram shows a situation where the through holes 3111 are arranged in an array.

[0072] Further, see Figure 1 As shown, the battery pack in this embodiment further includes a fixing belt 40, which is sleeved on the outer periphery of the battery cell assembly 20 and the first heat sink 31. After the first heat sink 31, the second heat sink 32 and the battery cell assembly 20 are installed, the first heat sink 31, the second heat sink 32 and the battery cell assembly 20 are bundled and fixed by the fixing belt 40 in this embodiment, which effectively prevents the first heat sink 31, the second heat sink 32 and the battery cell assembly 20 from falling off during operation, and at the same time increases the degree of fit between the first heat sink 31, the second heat sink 32 and the battery cell assembly 20, further improving the heat conduction between the first heat sink 31 and the second heat sink 32.

[0073] Optionally, the fixing tape 40 in this embodiment includes fiber tape, acetate cloth or self-adhesive tape; the number of fixing tapes 40 may include one, two, three or more, which can be selected according to the actual length of the battery cell 21. Figure 1 The figure shows a situation where there are two fixing belts 40 , and the two fixing belts 40 are sleeved on two opposite ends of the battery cell assembly 20 along the second direction (ie, the length direction of the battery pack).

[0074] Further, see Figure 1 As shown, the battery pack in this embodiment further includes a third foam layer 50, which is disposed between every two adjacent battery cells 21. Since the third foam layer 50 has a certain elasticity, it can be deformed when squeezed, and the raw materials are simple and easy to obtain. When the battery cell 21 expands during operation, the third foam layer 50 can be squeezed. At this time, the third foam layer 50 can absorb the expansion of the battery cell 21, play a buffering role for the battery cell 21, and is beneficial to the protection of the battery cell 21.

[0075] Optionally, the third foam layer 50 disposed between each two adjacent battery cells 21 may include one, two, three or more. Figure 1 The figure shows the situation when two third foam layers 50 are arranged between every two adjacent battery cells 21 .

[0076] Specifically, Figure 8 The temperature changes of the battery pack of the present application and the battery pack of the control group (the first heat sink 31, the second heat sink 32 and the third heat sink 33 are not provided) under working conditions are shown. Among them, the design parameters of the battery pack of the present application are as follows: the thickness of the first heat sink 31 is 0.15mm, the thickness of the first phase change sheet and the second phase change sheet 331 are both 1.2mm, and the thickness of the graphite sheet is 0.04mm. After testing, the temperature of the battery cell 21 of the present application can be reduced by up to 7°C. At the same time, the temperature between the battery cells 21 is reduced by 1.5°C (not shown in the drawings). It can be seen that the battery pack of the present application can control the battery temperature within a reasonable range.

[0077] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0078] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of this application.

[0079] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery pack, characterized in that: include: A housing (10) having a receiving space; A battery cell assembly (20) comprising a plurality of stacked battery cells (21), wherein the battery cell assembly (20) is arranged in the accommodating space; a first heat sink (31), wherein a plurality of the first heat sinks (31) are arranged in one-to-one correspondence with a plurality of the battery cells (21), the first heat sink (31) comprising a main body section (311) and a first bending section (312), the main body section (311) being arranged on a first side surface (211) of the battery cell (21), the first bending section (312) being connected to the main body section (311) and being arranged on a second side surface (212) of the battery cell (21) adjacent to the first side surface (211); The second heat sink (32) is arranged on a side of the first bent section (312) facing away from the battery core assembly (20), and the second heat sink (32) comprises a heat absorption layer (321) and a heat conduction layer (323), wherein the heat conduction layer (323) covers the heat absorption layer (321).

2. The battery pack according to claim 1, characterized in that: The heat absorption layer (321) includes a first phase change sheet, and the heat conduction layer (323) includes a graphite sheet.

3. The battery pack according to claim 1, characterized in that: The second heat sink (32) further comprises a first foam layer (322), and along a first direction, the heat absorption layer (321), the first foam layer (322) and the heat conduction layer (323) are sequentially stacked, and the heat conduction layer (323) covers the heat absorption layer (321) and the first foam layer (322).

4. The battery pack according to claim 3, characterized in that: Along the first direction, the thickness T1 of the heat absorption layer (321) satisfies the relationship: T1>1 mm; and / or, Along the first direction, the thickness T2 of the first foam layer (322) satisfies the relationship: 0.5 mm ≤ T2 ≤ 1.5 mm; and / or, Along the first direction, the thickness T3 of the heat-conducting layer (323) satisfies the relationship: T3 ≥ 0.04 mm.

5. The battery pack according to claim 1, characterized in that: When the discharge rate of the battery cell (21) is less than 4C, the thickness T1 of the heat absorption layer (321) satisfies the relationship: 1 mm < T1 < 2 mm; and / or, When the discharge rate of the battery cell (21) is greater than 4C, the thickness T1 of the heat absorption layer (321) satisfies the relationship: 2mm<T1<3mm.

6. The battery pack according to claim 1, characterized in that: The battery pack further comprises a third heat sink (33), the third heat sink (33) being arranged on a third side surface (213) of the battery cell (21) adjacent to the first side surface (211), the third heat sink (33) comprising a second phase change sheet (331) and a second foam layer (332), and the second phase change sheet (331) and the second foam layer (332) being stacked in sequence along a second direction.

7. The battery pack according to claim 6, characterized in that: The first heat sink (31) further comprises a second bent section, the second bent section being connected to the main section (311) and arranged on the third side surface (213), and the third heat sink (33) being arranged on a side of the second bent section facing away from the battery cell assembly (20).

8. The battery pack according to claim 7, characterized in that: Along the third direction, the thickness T4 of the first heat sink (31) satisfies the relationship: T4 ≥ 0.15 mm; and / or, Along the third direction, the width D1 of the first bending section (312) and the width D2 of the battery cell (21) satisfy the relationship: 0.5D2≤D1≤D2; and / or, Along the third direction, the width D3 of the second bent section and the width D2 of the battery cell (21) satisfy the relationship: 0.5D2≤D3≤D2.

9. The battery pack according to claim 1, characterized in that: The main body section (311) is provided with a through hole (3111), and the through hole (3111) includes a plurality of through holes, and the sum S1 of the projection areas of the plurality of through holes (3111) along the third direction on the first side surface (211) and the surface area S2 of the main body section (311) satisfy the relationship: S1 / S2<0.

3.

10. The battery pack according to claim 1, characterized in that: The battery pack further comprises a fixing belt (40), wherein the fixing belt (40) is sleeved on the outer periphery of the battery cell assembly (20) and the first heat sink (31); and / or the battery pack further comprises a third foam layer (50), wherein the third foam layer (50) is arranged between every two adjacent battery cells (21).

Images