Patent Publication Number: US-2021167441-A1

Title: Battery pack, method for manufacturing battery pack and vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a national stage of International Application No. PCT/CN2020/091228, filed on May 20, 2020, which claims priority to Chinese Patent Application No. 201910565343.5, filed on Jun. 27, 2019. Both of the aforementioned applications are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The present application relates to the technical field of batteries, in particular to a battery pack, a method for manufacturing a battery pack, and a vehicle. 
     BACKGROUND 
     In recent years, rechargeable batteries have been widely applied to powering high-power devices, such as electric vehicles. The rechargeable batteries can achieve larger capacity or power by connecting a plurality of battery cells in series, in parallel or in series and parallel. 
     Various battery cells integrally form a battery assembly. In order to take away heat generated during a working process of the battery assembly so that a battery pack has good working performance, a prior art known to the inventor is to provide a temperature control system for cooling at the bottom of a case. 
     However, when such a temperature control system is utilized to cool the battery assembly, since the temperature control system can only cool one side of the battery assembly, the other side is completely dependent on the battery assembly itself for heat transfer, and it is easy to cause the battery assembly to form a temperature difference in a height direction. The side of the battery assembly close to the temperature control system has a faster cooling rate, and an effect of adjustment by the temperature control system is more obvious, while the side of the battery assembly away from the temperature control system has a slower cooling rate, and an effect of adjustment by the temperature control system is poorer. When the temperature difference between the two sides of the battery assembly is large for a long term, a service life  of the battery assembly will be affected. 
     SUMMARY 
     Embodiments of the present application provide a battery pack, a method for manufacturing a battery pack, and a vehicle, which can increase a service life of the battery pack. 
     According to an aspect of the present application, there is provided a battery pack, including: 
     a case assembly including a case, a thermally conductive beam and a temperature control component, the thermally conductive beam being disposed in the case and connected to the case, and the temperature control component being disposed in a bottom region of the case; 
     a thermally conductive cover connected to the thermally conductive beam and located above the thermally conductive beam along a height direction of the battery pack, where the thermally conductive cover, the case and the thermally conductive beam enclose and form a first chamber; and 
     a plurality of battery cells integrally forming a battery assembly, the battery assembly being disposed in the first chamber and above the temperature control component. 
     In some embodiments, the battery pack further includes a thermal barrier layer disposed between a bottom surface of the battery assembly and an inner bottom surface of the case, where a thermal conductivity coefficient of the thermal barrier layer is smaller than a thermal conductivity coefficient of the thermally conductive beam or the thermally conductive cover. 
     In some embodiments, the thermally conductive cover and the thermally conductive beam adopt contact heat conduction. 
     In some embodiments, the thermally conductive cover and a top of the battery assembly adopt contact heat conduction. 
     In some embodiments, at least one of the thermally conductive beam and the thermally conductive cover, and a side surface of the battery assembly away from a pole adopt contact heat conduction. 
     In some embodiments, the thermally conductive cover includes a main body part and a mounting part connected to the main body part, the main body part covers the battery assembly, and the mounting part is fixedly connected to the thermally conductive beam.  
     In some embodiments, the battery pack further includes a first thermally conductive layer disposed between the mounting part and the thermally conductive beam. 
     In some embodiments, the battery pack further includes a second thermally conductive layer disposed between the main body part and the thermally conductive beam, and a side surface of the battery assembly away from a pole. 
     In some embodiments, the battery pack further includes a third thermally conductive layer disposed between the main body part and a top of the battery assembly. 
     In some embodiments, the battery pack further includes a cover body disposed on the top of the thermally conductive cover, fixed and sealed with the case. 
     In some embodiments, the battery cell includes a housing and an electrode assembly disposed in the housing, and the electrode assembly includes a first electrode sheet, a second electrode sheet, and a diaphragm disposed between the first electrode sheet and the second electrode sheet; 
     where the electrode assembly is in a coiled structure and is flat-shaped, and an outer surface of the electrode assembly includes two flat surfaces; or, the electrode assembly is in a laminated structure, and the first electrode sheet and the second electrode sheet are disposed in a stacking manner; and 
     the flat surfaces of the electrode assembly or a plane where the first electrode sheet is located is disposed to face a bottom surface of the case, and the plurality of battery cells are provided with a single layer or at least two layers disposed in a stacking manner along the height direction of the battery pack. 
     In other embodiments, the battery cell includes a housing and an electrode assembly disposed in the housing, and the electrode assembly includes a first electrode sheet, a second electrode sheet, and a diaphragm disposed between the first electrode sheet and the second electrode sheet; 
     where the electrode assembly is in a coiled structure and is flat-shaped, and an outer surface of the electrode assembly includes two flat surfaces; or, the electrode assembly is in a laminated structure, and the first electrode sheet and the second electrode sheet are disposed in a stacking manner; and 
     the flat surfaces of the electrode assembly or a plane where the first electrode sheet is located is disposed to face a side surface of the case, and the plurality of battery cells are disposed in a stacking manner along a length direction or a width direction of the battery pack. 
     In some embodiments, the battery assembly is divided into at least two groups in a plane perpendicular to the height direction of the battery pack, and the thermally conductive  beam and a side surface of the battery assembly away from a pole adopt contact heat conduction, and a grouping direction of the battery assembly is perpendicular to an extension direction of the thermally conductive beam. 
     In some embodiments, a ratio of a thickness of the thermal barrier layer to a height of the thermally conductive beam ranges from 1/5 to 1/500; and/or a ratio of the thermal conductivity coefficient of the thermal barrier layer to the thermal conductivity coefficient of the thermally conductive beam or the thermally conductive cover ranges from 0.001 to 0.5. 
     In some embodiments, the battery pack further includes a thermal barrier layer disposed between a bottom of the battery assembly and an inner bottom surface of the case. 
     In some embodiments, a ratio of a thickness of the first thermally conductive layer to a thickness of the thermal barrier layer ranges from 0.0001 to 0.1. 
     In some embodiments, a ratio of a thermal conductivity coefficient of the first thermally conductive layer to a thermal conductivity coefficient of the thermal barrier layer ranges from 20 to 1000. 
     In some embodiments, a ratio of a thickness of the second thermally conductive layer to a thickness of the thermal barrier layer ranges from 0.0001 to 0.1. 
     In some embodiments, a ratio of a thermal conductivity coefficient of the second thermally conductive layer to a thermal conductivity coefficient of the thermal barrier layer ranges from 20 to 1000. 
     In some embodiments, a ratio of a thickness of the third thermally conductive layer to a thickness of the thermal barrier layer ranges from 0.0001 to 0.1. 
     In some embodiments, a ratio of a thermal conductivity coefficient of the third thermally conductive layer to a thermal conductivity coefficient of the thermal barrier layer ranges from 20 to 1000. 
     According to another aspect of the present application, there is provided a vehicle, including: 
     a vehicle main body; and 
     the battery pack of the above embodiments, where the battery pack is disposed in the vehicle main body. 
     According to a third aspect of the present application, there is provided a method for manufacturing a battery pack, including: 
     providing a case assembly including a case, a thermally conductive beam and a temperature control component, the thermally conductive beam being disposed in the case and connected to the case, and the temperature control component being disposed in a bottom  region of the case; 
     providing a thermally conductive cover connected to the thermally conductive beam and located above the thermally conductive beam along a height direction of the battery pack, where the thermally conductive cover, the case and the thermally conductive beam enclose and form a first chamber; and 
     providing a plurality of battery cells integrally forming a battery assembly, the battery assembly being disposed in the first chamber and above the temperature control component. Based on the above technical solutions, a battery pack of one embodiment of the present application is provided with a thermally conductive beam and a thermally conductive cover, so that while a temperature control component adjusts temperature at a bottom of a case, the heat can be transferred to the thermally conductive beam and the thermally conductive cover in sequence, which changes a thermal conduction path of temperature adjustment and control on a battery assembly by the temperature control component, can balance temperature distribution in a first chamber along a height direction of the battery pack, reduce a temperature difference between upper and lower regions of the battery assembly, improve the extent of temperature uniformity of the battery assembly, and make consistency of a depth of discharge of the battery assembly improved, thereby increasing a service life of the battery pack. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings described herein are intended to provide further understanding of the present application and constitute part of the present application, and illustrative embodiments of the present application and description thereof are used for explaining the present application and do not constitute an undue limitation to the present application. In the drawings: 
         FIG. 1  is a schematic exploded diagram of an embodiment of a battery pack of the present application; 
         FIG. 2  is a front view of the battery pack shown in  FIG. 1 ; 
         FIG. 3  is a schematic structural diagram of an embodiment of a case assembly in the battery pack shown in  FIG. 1 ; 
         FIG. 4  is a front view of the case assembly shown in  FIG. 3 ; 
         FIG. 5  is a schematic structural diagram of a plurality of battery cells in the battery pack shown in  FIG. 1  disposed in a stacking manner along a height direction; 
         FIG. 6  is a schematic structural diagram of a single battery cell in the battery pack shown in  FIG. 1 ; 
         FIG. 7  is a schematic exploded diagram of an embodiment of a battery cell in a battery pack; 
         FIG. 8  is a cross-sectional view of a battery cell using a coiled electrode assembly along an x-z plane in  FIG. 7 ; 
         FIG. 9  is a cross-sectional view of a battery cell using a laminated electrode assembly along an x-z plane in  FIG. 7 ; 
         FIG. 10  is a schematic exploded diagram of another embodiment of a battery pack of the present application; 
         FIG. 11  is a schematic diagram of a state in which a cover body of the battery pack shown in  FIG. 10  is opened; 
         FIG. 12  is a front view of the battery pack shown in  FIG. 10 ; and 
         FIG. 13  is a schematic structural diagram of a plurality of battery cells in the battery pack shown in  FIG. 10  stacked along a length direction. 
     
    
    
     DESCRIPTION OF REFERENCE SIGNS 
       1 . Case assembly;  11 . Case;  111 . First flange;  112 . First hole;  12 . Thermally conductive beam;  121 . Second hole;  13 . Temperature control component; 
       2 . Battery cell;  20 . Battery assembly;  20 ′. Plate;  21 . Housing;  22 . Electrode assembly;  221 . First electrode sheet;  222 . Second electrode sheet;  223 . Diaphragm;  224 . Flat surface;  23 . Adapter plate;  24 . Cover plate assembly;  241 . Cover plate;  242 . First electrode terminal;  243 . Second electrode terminal; 
       3 . Thermally conductive cover;  31 . Main body part;  32 . Mounting part;  321 . Third hole; 
       4 . Cover body;  41 . Second flange;  411 . Fourth hole; 
       5 . Fastener;  6 . Thermal barrier layer;  7 . First thermally conductive layer;  8 . Second thermally conductive layer;  9 . Third thermally conductive layer. 
     DESCRIPTION OF EMBODIMENTS 
     The present application will be described in detail below. In the following paragraphs, different aspects of embodiments are defined in more detail. Various aspects defined in this way can be combined with any other aspect or aspects, unless it is clearly indicated that they cannot be combined. In particular, any feature considered to be preferred or advantageous may be combined with one or more other features considered to be preferred or  advantageous. 
     The terms “first”, “second” and the like in the present application are only for convenience of description, and are used to distinguish different components with the same name, rather than to indicate a specific order or primary-secondary relationship. 
     In addition, when an element is referred to as being “on” another element, the element may be directly on the other element, or may be indirectly on the other element with one or more intermediate elements interposed therebetween. In addition, when an element is referred to as being “connected to” another element, the element may be directly connected to the other element, or may be indirectly connected to the other element with one or more intermediate elements interposed therebetween. In the following, the same reference signs denote the same elements. 
     The phrase “a plurality of” in the present application refers to more than two (including two). Similarly, the phrase “a plurality of groups” refers to more than two groups (including two groups), and the phrase “a plurality of lengths” refers to more than two lengths (including two lengths). 
     In order to clearly describe various orientations in the following embodiments, a coordinate system in  FIG. 1  for example defines various directions of a battery pack, in which an x direction represents a length direction of the battery pack; a y direction represents a width direction of the battery pack; and a z direction is perpendicular to a plane formed by the x direction and the y direction and represents a height direction of the battery pack. When the battery pack is installed on a vehicle, the height direction of the battery pack is parallel to a vertical direction. The vertical direction mentioned here is allowed to have a certain angular deviation from a theoretical vertical direction. Based on such definition of the orientation, “up”, “down”, “top” and “bottom” are used, all of which are relative to the height direction. 
     In some embodiments, the present application provides a vehicle. The vehicle includes a vehicle main body and a battery pack, and the battery pack is disposed in the vehicle main body. The vehicle is a new-energy vehicle, which may be a battery electric vehicle, or may also be a hybrid electric vehicle or an extended-range vehicle. A drive motor is disposed in the vehicle main body, and the drive motor is electrically connected to the battery pack. The battery pack provides electrical energy, and the drive motor is connected to wheels on the vehicle main body through a transmission mechanism to drive the vehicle to travel. Preferably, the battery pack may be horizontally disposed at the bottom of the vehicle main body, and can be installed by top-hung and/or bottom-supported methods. 
       FIG. 1  is a schematic structural diagram of an embodiment of a battery pack of the  present application. The battery pack  100  includes a case assembly  1 , a thermally conductive cover  3  and a plurality of battery cells  2  integrally forming a battery assembly  20 . 
     The case assembly  1  includes a case  11 , a thermally conductive beam  12  and a temperature control component  13 . The case  11  has an opening end, and the thermally conductive beam  12  is fixed in the case  11  and connected to the case  11  so that the temperature control component  13 , the case  11 , the thermally conductive beam  12  and the thermally conductive cover  3  can conduct heat to one another, for example, the thermally conductive beam  12  can be fixed on an inner bottom surface or a side wall of the case  11 . The temperature control component  13  is disposed in a bottom region of the case  11 , and can be provided inside or outside the case  11 , or integrated with a bottom plate of the case  11 . The temperature control component  13  is used to adjust temperature of the battery assembly  20 , for example, in order to take away heat generated during a working process of the battery assembly  20 , the battery assembly  20  may be cooled. The temperature control component  13  includes a cooling pipe arranged at the bottom of the case  11  and a circulating component for feeding a cooling liquid into the cooling pipe; or the temperature control component  13  includes a liquid cooling plate disposed at the bottom of the case  11 ; or when the battery pack is used in a low temperature area, the battery cells of the battery assembly  20  can be heated, and the temperature control component  13  is included in an electric heating element arranged at the bottom of the case  11  or the like. 
     The thermally conductive cover  3  is connected to the thermally conductive beam  12  and is located above the thermally conductive beam  12  along a height direction of the battery pack. The thermally conductive cover  3 , the inner bottom surface of the case  11  and an inner side surface of the thermally conductive beam  12  form a first chamber A. Preferably, a size of the first chamber A is adapted to overall external size of each battery cell  2 . The battery assembly  20  is disposed in the first chamber A and above the temperature control component  13  so that the temperature control component  13  can adjust temperature under the battery assembly  20 . 
     Specifically, the thermally conductive beam  12  may adopt a solid beam or a hollow beam, and use of the hollow beam has better thermal conduction efficiency. A cross section of the thermally conductive beam  12  may be rectangular, trapezoidal or C-shaped, etc., and its upper surface may be set to be flat so as to fix the thermally conductive cover  3  on the upper surface of the thermally conductive beam  12 . Optionally, the thermally conductive cover  3  may also be fixed on a side surface of the thermally conductive beam  12 . The thermally conductive beam  12  may be designed as a continuous structure in its extension direction, or may be  designed as a segmented structure. 
     In this embodiment, the thermally conductive beam  12  and the thermally conductive cover  3  are provided, so that while the temperature control component  13  adjusts temperature at the bottom of the case  11 , the heat can be transferred to the thermally conductive beam  12  and the thermally conductive cover  3  in sequence, which changes a thermal conduction path of temperature adjustment and control on the battery assembly  20  by the temperature control component  13 , can balance temperature distribution in the first chamber A along the height direction of the battery pack, reduces a temperature difference between upper and lower regions of the battery assembly  20 , and improves the extent of temperature uniformity of the battery assembly  20 , so as to make consistency of a depth of discharge of the battery assembly  20  improved. Moreover, the thermally conductive cover  3  can also restrain the battery assembly  20  from expanding in the height direction of the battery pack. Both of these advantages can increase a service life of the battery pack. 
     Further, as shown in  FIG. 1 , the battery pack may further include a thermal barrier layer  6  disposed between a bottom surface of the battery assembly  20  and an inner bottom surface of the case  11 . A thermal conductivity coefficient of the thermal barrier layer  6  is smaller than a thermal conductivity coefficient of the thermally conductive beam  12  or the thermally conductive cover  3 , which can hinder heat transfer between the temperature control component  13  and the bottom of the battery assembly  20 , delay a temperature adjustment effect of the temperature control component  13  on the bottom of the battery assembly  20 , and prevent the temperature control component  13  from directly adjusting temperature of the battery cells  2  through a bottom bearing surface of the case  11 . It should be noted that it is not required that the thermal barrier layer  6  is completely heat-insulated, as long as thermal conduction efficiency can be reduced, and a non-metallic material is preferred. For example, the thermal barrier layer  6  may adopt glass fiber, asbestos, rock wool, silicate or aerogel felt. More preferably, the thermal barrier layer  6  also has a function of an adhesive, so as to reliably fix the battery cells  2  in the case  11  and improve structural strength of the whole battery pack. 
     In this embodiment, the thermal barrier layer  6  is provided to enable heat released by the temperature control component  13  to be first transferred to the thermally conductive beam  12  and the thermally conductive cover  3  in sequence before a temperature adjustment effect of the temperature control component  13  reaches the bottom of the battery assembly  20 , so that temperature of the bottom of the case  11 , the thermally conductive beam  12  and the thermally conductive cover  3  are uniform, and as a result, the heat can be substantially transferred from different surfaces of the battery assembly  20  to the battery assembly  20  at the  same time, thereby further reducing a temperature difference of the battery assembly  20  along the height direction of the battery pack and increasing a service life of the battery pack. 
     As shown in  FIG. 2 , the battery assembly  20  includes two layers of battery cells  2  in the height direction of the battery pack, and the thermal barrier layer  6  is disposed between the bottom layer of battery cells  2  and the inner bottom surface of the case  11 . The thermal barrier layer  6  can be configured as a whole piece to sufficiently hinder the heat transfer between the temperature control component  13  and the bottom of the battery assembly  20 , so that the heat can quickly reach the top of the battery assembly  20  through the thermally conductive beam  12  and the thermally conductive cover  3 . Alternatively, for a structure in which the battery assembly  20  includes a plurality of groups of battery cells  2 , a thermal barrier layer  6  can be disposed between a bottom surface of each group of battery cells  2  and the inner bottom surface of the case  11 , which can save the material amount of the thermal barrier layer  6 , also enable heat released by the temperature control component to be transferred to the top of the battery assembly  20  through a space between adjacent groups of battery cells  2 , and reduce a temperature difference between upper and lower regions in the first chamber A. 
     Preferably, a ratio of a thickness of the thermal barrier layer  6  to a height of the thermally conductive beam  12  ranges from 1/5 to 1/500, for example, 1/5, 1/10, 1/30, 1/40, 1/50, 1/60, 1/70, 1/80, 1/90, 1/100, 1/200, 1/300, 1/400 or 1/500, etc. 
     Preferably, a ratio of a thermal conductivity coefficient of the thermal barrier layer  6  to a thermal conductivity coefficient of the thermally conductive beam  12  or the thermally conductive cover  3  ranges from 0.001 to 0.5, for example, 0.001, 0.01, 0.1, 0.2, 0.3, 0.4, or 0.5, etc. 
     In some embodiments, a preset gap can be set between the thermally conductive cover  3  and the thermally conductive beam  12  to conduct heat through air. In other embodiments, the thermally conductive cover  3  and the thermally conductive beam  12  adopt contact heat conduction, which can reduce heat transfer time between the thermally conductive beam  12  and the thermally conductive cover  3 , improve thermal conductivity efficiency, and shorten time required for temperature adjustment to reach a stable state. 
     For example, as shown in  FIG. 1 , the thermally conductive cover  3  includes a main body part  31  and a mounting part  32  connected to the main body part  31 , and the main body part  31  covers the battery assembly  20 . For example, the battery assembly  20  includes at least two layers of battery cells  2 , the main body part  31  can cover the topmost layer of battery cells  2 , and the mounting part  32  is fixedly connected to the thermally conductive beam  12 . For example, the thermally conductive cover  3  may be formed by bending a flat plate structure.  The thermally conductive cover  3  and the thermally conductive beam  12  may be in direct contact, or the battery pack further includes a first thermally conductive layer  7  disposed between the mounting part  32  and the thermally conductive beam  12 . The first thermally conductive layer  7  may be formed by filling thermal conductive glue. The thermal conductive glue can eliminate a gap between the mounting part  32  and the thermally conductive beam  12 . Compared with a direct contact method, thermal conductivity efficiency can be improved to enable a temperature adjustment effect of the temperature control component  13  to be transferred to the main body part  31  through the thermally conductive beam  12  and the mounting part  32  more quickly, so that heat is transferred from the main body part  31  to a top surface of the battery assembly  20 ; in addition, since the top surface of the battery assembly  20  has a larger thermal conduction area, a temperature difference between upper and lower regions of the battery assembly  20  can be balanced. 
     As shown in  FIG. 2 , the main body part  31  of the thermally conductive cover  3  protrudes in a direction away from the battery cells  2  relative to the mounting part  32  as a whole. This structure can not only reduce an installation height of the thermally conductive beam  12  and ensure strength of the thermally conductive beam  12 , but also can prevent a fastener  5  from protruding from a top surface of the main body part  31  when the mounting part  32  and the thermally conductive beam  12  are fixed by the fastener  5 , and can reduce the height of the battery pack. 
     For this structure, in some embodiments, the main body part  31  dads top surfaces and part of side surfaces of the battery cells  2  at the same time. As shown in  FIG. 2 , the battery assembly  20  is provided with two groups of battery cells  2  along the width direction (y direction) of the battery pack, and poles of the two groups of battery cells  2  are arranged oppositely, and there is a preset interval between the two groups of battery cells  2  for setting a bus bar. In order to reduce space occupied by the battery pack in a grouping direction of the battery assembly  20 , the thermally conductive beam  12  and a side surface of the battery assembly  20  adopt contact heat conduction, and/or the main body part  31  and a side surface of the battery assembly  20  adopt contact heat conduction. This manner can reduce heat transfer time between the thermally conductive beam  12  and the main body part  31 , and the side surface of the battery assembly  20 , improve thermal conduction efficiency, and shorten time required for temperature adjustment to reach a stable state. 
     The thermally conductive cover  3  and the thermally conductive beam  12  may also be in direct contact with the battery assembly  20 . Alternatively, as shown in  FIG. 1 , the battery pack may further include a second thermally conductive layer  8 , and the second thermally  conductive layer  8  is disposed between the thermally conductive cover  3  and the thermally conductive beam  12 , and a side surface of the battery assembly  20 . The second thermally conductive layer  8  may be formed by filling thermal conductive glue, and the thermal conductive glue can eliminate gaps between the thermally conductive cover  3  and the thermally conductive beam  12 , and the side surface of the battery assembly  20 . Compared with a direct contact method, this manner can improve thermal conductivity efficiency and allow a temperature adjustment effect of the temperature control component  13  to be simultaneously transferred to the side surface of the battery assembly  20  through the thermally conductive beam  12  and the main body part  31  so as to improve temperature adjustment efficiency. 
     Optionally, on the basis of  FIG. 2 , in order to improve explosion-proof safety, two groups of battery cells  2  are disposed opposite to each other on a surface away from the pole, respectively. The thermally conductive beam  12  is kept at a preset distance from the side surface of the battery assembly  20 , which can conduct heat through air. 
     As shown in  FIG. 2 , the main body part  31  of the thermally conductive cover  3  and the top surface of the battery assembly  20  may also be in direct contact. Alternatively, as shown in  FIG. 2 , the battery pack may further include a third thermally conductive layer  9  disposed between the thermally conductive cover  3  and the top surface of the battery assembly  20 , and the third thermally conductive layer  9  may be formed by filling thermally conductive glue. Preferably, the main body part  31  may completely cover top surfaces of various battery cells  2  to increase temperature adjustment capability on the top of the battery assembly  20 . 
     Preferably, a ratio of a thickness of the first thermally conductive layer  7 , the second thermal conductive layer  8  and/or the third thermally conductive layer  9  to a thickness of the thermal barrier layer  6  ranges from 0.0001 to 0.1, for example, 0.0001, 0.001, 0.01 or 0.1; and/or a ratio of a thermal conductivity coefficient of the first thermally conductive layer  7 , the second thermally conductive layer  8  and/or the third thermally conductive layer  9  to a thermal conductivity coefficient of the thermal barrier layer  6  ranges from 20 to 1000, for example, 20, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900 or 1000, etc. 
     The first thermally conductive layer  7 , the second thermally conductive layer  8  and/or the third thermally conductive layer  9  in the above embodiments can make temperature of the temperature control component  13  evenly distributed to a height space of the first chamber A through the thermally conductive beam  12  and the thermally conductive cover  3 , so that uniformity of temperature throughout the battery assembly  20  is improved. In addition, each thermally conductive layer can also function as an adhesive, so as to improve reliability of fixing each battery cell  2  and improve structural strength of the battery assembly  20 .  Moreover, when the battery pack is used in a vehicle, the vehicle will transfer vibration to the battery pack during driving, and the first thermally conductive layer  7 , the second thermally conductive layer  8  and/or the third thermally conductive layer  9  can also play a role in buffering the vibration, thereby improving working reliability of the battery assembly  20 . 
     As shown in  FIG. 1 , the battery pack of the present application may further include a cover body  4  disposed on the top of the thermally conductive cover  3 , covered to the opening end of the case  11 , and fixed and sealed with the case  11 . The cover body  4  and the thermally conductive cover  3  are provided independently, which can play the role of closing the case  11 . Moreover, since the thermally conductive cover  3  is provided, deformation of the cover body  4  can be reduced, thereby improving sealing performance of the battery pack. 
     There is a preset gap between an inner surface of the cover body  4  and an outer surface of the thermally conductive cover  3 . By reserving an expansion space for the battery assembly  20 , a force generated after deformation of the thermally conductive cover  3  can be prevented from being transferred to the cover body  4  to force the cover body  4  to deform as well; moreover, even if the battery assembly  20  expands to cause the thermally conductive cover  3  to deform and push against the cover body  4 , the cover body  4  can also further restrict the deformation of the thermally conductive cover  3  and the expansion of the battery assembly  20 . Preferably, for battery packs of different sizes, the preset gap ranges from 2 mm to 100 mm. 
     Specifically, as shown in  FIG. 1 , in order to realize fixation of the cover body  4  and the case  11 , a first flange  111  is disposed around the opening end of the case  11 , and a second flange  41  is disposed around the cover body  4 . The first flange  111  and the second flange  41  may be fixed by means of bonding or fastener connection. For example, the first flange  111  is provided with a plurality of first holes  112  at intervals, and the second flange  41  is provided with a plurality of fourth holes  411  at intervals, and the fourth holes  411  and the first holes  112  are penetrated by a fastener  5  to realize the fixation of the cover body  4  and the case  11 . 
     In order to realize fixation of the thermally conductive cover  3  and the thermally conductive beam  12 , the mounting part  32  is provided with a plurality of third holes  321  at intervals along an extension direction of the thermally conductive beam  12 , and the top of the thermally conductive beam  12  is provided with a plurality of second holes  121  at intervals along its extension direction. The third holes  321  and the second holes  121  are penetrated by the fastener  5  to fix the thermally conductive cover  3  and the thermally conductive beam  12 . 
     Optionally, extension parts may also be provided at two opposite ends of the thermally conductive cover  3  so that the thermally conductive cover  3  is fixed with the case  11  through the extension parts. This structure can omit the cover body  4  so as to simplify the  structure of the battery pack and reduce the weight. 
     As shown in  FIG. 1 , the battery assembly  20  is divided into at least two groups in a plane perpendicular to the height direction of the battery pack, and a grouping direction is perpendicular to an extension direction of the thermally conductive beam  12 . Various groups of battery cells  2  can be disposed at intervals. 
     By arranging the battery assembly  20  in groups, when some battery cells  2  work to generate a large amount of heat and thermal runaway occurs, the heat can be delayed to diffuse towards battery cells of other groups and working safety of the battery assembly  20  is improved, so that even if some battery cells  2  cannot work normally, the battery pack can also be used at a reduced power. Moreover, the grouping direction is perpendicular to the extension direction of the thermally conductive beam  12 , so that various groups of battery cells  2  can be continuously arranged along the extension direction of the thermally conductive beam  12 . Because the thermally conductive beam  12  and the battery cells  2  of the corresponding group have a continuous thermally conductive region, a temperature adjustment effect of the temperature control component  13  can be efficiently transferred to other regions other than the bottom of the battery assembly  20  through the thermally conductive beam  12 . Optionally, the grouping direction of the battery assembly  20  may also be the same as the extension direction of the thermally conductive beam  12 . 
     As shown in  FIG. 1 , the case  11  is rectangular, and the thermally conductive beam  12  extends along a length direction of the case  11 . Such a structure can increase the length of the thermally conductive beam  12 , so that a temperature adjustment effect of the temperature control component  13  is more efficiently transferred to the battery assembly  20  through the thermally conductive beam  12 . Optionally, the thermally conductive beam may also extend along a width direction of the case  11 . 
     As shown in  FIGS. 3 and 4 , the case  11  is provided with two thermally conductive beams  12  extending along the length direction of the case  11 . Each battery cell  2  is located between the two thermally conductive beams  12 , and the thermally conductive beams  12  and inner side walls of the case  11  may be disposed at intervals. Further, in order to optimize a thermal conduction effect and shorten time required for temperature adjustment to reach a stable state, a rectangular ring-shaped thermally conductive beam  12  may also be provided to surround the outer periphery of the battery assembly  20 . At the same time, the shape of the mounting part  32  of the thermally conductive cover  3  is adapted to the thermally conductive beam  12 . Alternatively, a thermally conductive beam  12  may also be disposed between adjacent groups of battery cells  2 .  
     As shown in  FIG. 5 , it is a schematic structural diagram of a single group of battery cells  2 ,  FIG. 6  is a schematic structural diagram of a single battery cell, and  FIG. 7  is a schematic exploded diagram of a single battery cell. Each battery cell  2  includes: a housing  21  and an electrode assembly  22  disposed in the housing  21 . The housing  21  may have a hexahedral shape or other shapes, and have an opening. The electrode assembly  22  is accommodated in the housing  21 . The opening of the housing  21  is covered with a cover plate assembly  24 . The cover plate assembly  24  includes a cover plate  241  and two electrode terminals disposed on the cover plate. The two electrode terminals are a first electrode terminal  242  and a second electrode terminal  243 , respectively. The first electrode terminal  242  may be a positive electrode terminal, and the second electrode terminal  243  may be a negative electrode terminal. In other embodiments, the first electrode terminal  242  may also be a negative electrode terminal, and the second electrode terminal  243  may be a positive electrode terminal. An adapter plate  23  is disposed between the cover plate assembly  24  and the electrode assembly  22 , and an electrode tab of the electrode assembly  22  is electrically connected to an electrode terminal on the cover plate  241  through the adapter plate  23 . In this embodiment, there are two adapter plates  23 , namely, a positive electrode adapter plate and a negative electrode adapter plate, respectively. 
     As shown in  FIG. 7 , two electrode assemblies  22  are disposed in the housing  21 , and the two electrode assemblies  22  are stacked along a height direction (z direction) of a battery cell  2 , where the height direction of the battery cell  2  is the same as the height direction of the battery pack. Certainly, in other embodiments, one electrode assembly  22  may also be disposed in the housing  21 , or more than three electrode assemblies  22  may be disposed in the housing  21 . The plurality of electrode assemblies  22  are stacked in the height direction (z direction) of the battery cell  2 . 
     As shown in  FIGS. 8 and 9 , the electrode assembly  22  includes a first electrode sheet  221 , a second electrode sheet  222  and a diaphragm  223  disposed between the first electrode sheet  221  and the second electrode sheet  222 . The first electrode sheet  221  may be a positive electrode sheet, and the second electrode sheet  222  may be a negative electrode sheet. In other embodiments, the first electrode sheet  221  may also be a negative electrode sheet, and the second electrode sheet  222  may be a positive electrode sheet. The diaphragm  223  is an insulator between the first electrode sheet  221  and the second electrode sheet  222 . An active material of the positive electrode sheet may be coated on a coating zone of the positive electrode sheet, and an active material of the negative electrode sheet may be coated on a coating zone of the negative electrode sheet. A portion extending from the coating zone of the  positive electrode sheet serves as a positive electrode tab; and a portion extending from the coating zone of the negative electrode sheet serves as a negative electrode tab. The positive electrode tab is connected to the positive electrode terminal on the cover plate assembly  24  through a positive electrode adapter plate. Similarly, the negative electrode tab is connected to the negative electrode terminal on the cover plate assembly  24  through a negative electrode adapter plate. 
     As shown in  FIG. 8 , the electrode assembly  22  is in a coiled structure. The first electrode sheet  221 , the diaphragm  223  and the second electrode sheet  222  are all belt-shaped structures. The first electrode sheet  221 , the diaphragm  223  and the second electrode sheet  222  are stacked in sequence and coiled more than two turns to form the electrode assembly  22 , and the electrode assembly  22  is in a flat shape. When the electrode assembly  22  is produced, the electrode assembly  22  may be directly coiled into a flat shape, or may be coiled into a hollow cylindrical structure first, and then flattened into a flat shape after the coiling.  FIG. 8  is a schematic diagram of an outline of an electrode assembly  22 . An outer surface of the electrode assembly  22  includes two flat surfaces  224 , and the two flat surfaces  224  are arranged oppositely along the height direction (z direction) of the battery cell  2 . The electrode assembly  22  is in a substantially hexahedral structure, and the flat surfaces  224  are substantially parallel to a coiling axis and are outer surfaces with the largest area. The flat surfaces  224  may be relatively flat surfaces, and are not required to be pure planes. 
     As shown in  FIG. 9 , the electrode assembly  22  is in a laminated structure, that is, the electrode assembly  22  includes a plurality of first electrode sheets  221 , a plurality of second electrode sheets  222 , and a diaphragm  223  is disposed between the first electrode sheet  221  and the second electrode sheet  222 . The first electrode sheet  221  and the second electrode sheet  222  are disposed in a stacking manner along the height direction (z direction) of the battery cell  2 . 
     Based on the structure of the battery cell  2  described above, the flat surfaces  224  of the electrode assembly  22  or a plane where the first electrode sheet  221  is located is disposed to face a bottom surface of the case  11 , and various battery cells  2  are provided with a single layer or at least two layers disposed in a stacking manner along the height direction. Various battery cells  2  may be fixed by bonding. Two ends of a single group of battery cells  2  in a horizontal plane along a stacking direction may be provided with plates  20 ′, which can limit the single group of battery cells  2  and protect the battery cells  2 , and can also function to insulate the battery cells  2  from the case  11  and the cover body  4  when an insulating material is used.  
     This arrangement can increase contact areas between the bottom of the case  11  and the thermally conductive cover  3 , and the battery cell  2 , thereby improving thermal conduction efficiency, and improving efficiency of temperature adjustment on the battery assembly  20 . Moreover, the electrode assembly  22  will inevitably expand along a thickness direction of an electrode sheet during charging and discharging processes. Expansion of various electrode sheets is superimposed, and accumulated expansion in the height direction is greater than that in other directions. The thermally conductive cover  3  can also restrict the direction of the maximum expansion of the battery cell  2  to prevent the battery pack from deforming and further increase a service life of the battery pack. In addition, this manner can make the posture of the battery cell  2  more stable during stacking and installation processes, which is beneficial to assembly operation. 
     In addition, the temperature control component  13  can adopt various installation methods. For example, the temperature control component  13  is provided on an outer bottom surface of the case  11  to transfer heat through the bottom of the case  11 . 
     Alternatively, as shown in  FIG. 4 , the case  11  is provided with a second chamber B, the temperature control component  13  is disposed in the second chamber B, the second chamber B is located at the bottom of the first chamber A, and the second chamber B is isolated from the first chamber A. This structure enables the first chamber A and the second chamber B to be independently provided. For a structure in which the temperature control component  13  uses liquid for heating or cooling, if liquid leakage occurs in the temperature control component, the liquid will not flow into the first chamber A, which can avoid safety accidents caused by the battery assembly  20  soaking in water, and improve safety of the battery pack. 
       FIGS. 10 to 13  are schematic structural diagrams of another embodiment of a battery pack of the present application. The battery pack  200  differs from the battery pack  100  shown in  FIGS. 1 to 9  in that various battery cells  2  are stacked in a different manner. 
     As shown in  FIG. 10  and  FIG. 11 , the battery cell  2  includes a housing and an electrode assembly disposed in the housing, and the battery cell  2  is in a side-standing state. Flat surfaces  224  of the electrode assembly  22  or a plane where a first electrode sheet  221  is located is disposed to face a side surface of a case  11 , and a plurality of battery cells  2  are disposed in a stacking manner along a length direction or a width direction of the case  11 . In order to improve stability of arrangement of the plurality of battery cells  2 , preferably, only one layer of battery cells  2  are disposed in a height direction of the battery pack. This arrangement can allow various battery cells  2  to be in contact with a bottom surface of the case  11  and a thermally conductive cover  3  at the same time, so that temperature between the various battery  cells  2  is more uniform, and overall working performance of the battery pack is improved; moreover, more battery cells  2  can be arranged in a single layer, which can reduce the number of layers in a height direction, and is beneficial to thermal conduction. 
       FIG. 12  is a front view of the battery pack shown in  FIG. 10 , and  FIG. 13  is a schematic diagram of a single group of battery cells  2 , and a plurality of battery cells  2  in the single group are stacked in sequence along an extension direction of a thermally conductive beam  12 . 
     In addition, the present application further provides a method for manufacturing the above-mentioned battery pack, including: 
     providing a case assembly ( 1 ) including a case ( 11 ), a thermally conductive beam ( 12 ) and a temperature control component ( 13 ), the thermally conductive beam ( 12 ) being disposed in the case ( 11 ) and connected to the case ( 11 ), and the temperature control component ( 13 ) being disposed in a bottom region of the case ( 11 ); 
     providing a thermally conductive cover ( 3 ) connected to the thermally conductive beam ( 12 ) and located above the thermally conductive beam ( 12 ) along a height direction of the battery pack, where the thermally conductive cover ( 3 ), the case ( 11 ) and the thermally conductive beam ( 12 ) enclose and form a first chamber (A); and 
     providing a plurality of battery cells ( 2 ) integrally forming a battery assembly ( 20 ), the battery assembly ( 20 ) being disposed in the first chamber (A) and located above the temperature control component ( 13 ). 
     The battery pack and the vehicle provided by the present application are described in detail above. Specific embodiments are applied in this text to describe principles and implementation manners of the present application. The description of the above embodiments is only used to help understand the method and core idea of the present application. It should be pointed out that for those of ordinary skill in the art, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.