Patent Publication Number: US-2023155257-A1

Title: Battery assembly, battery module, and method for manufacturing the same

Description:
FIELD 
     The subject matter herein generally relates to the field of heat dissipation of a battery, in particular, to a battery assembly, a battery module, and a method for manufacturing a battery assembly. 
     BACKGROUND 
     A battery is an important power source for a piece of equipment, such as an electric vehicle. In order to meet demand for high power of the piece of equipment, a plurality of battery cells are usually assembled together to form a battery module. The battery module should have over-current protection and thermal management functions to ensure safety. 
     In known battery modules, currents of the battery cells are usually collected through bus bars, fuses are installed to achieve over-current protection, and additional cooling pipes are installed to cool the battery module. However, the bus bars, fuses, and cooling pipes are all independent components, which require additional space for accommodation. In addition, the cooling pipes are installed at both ends of the battery cells, which may not meet the heat dissipation requirements of the battery module when it is used at high power. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Implementations of the present technology will now be described, by way of embodiment, with reference to the attached figures. 
         FIG.  1    is a cross-sectional view of a single-sided copper clad laminate including a first dielectric layer and a first copper layer according to an embodiment of the present disclosure. 
         FIG.  2    is a cross-sectional view showing grooves exposing a surface of the first copper layer and formed by removing part of the first dielectric layer of  FIG.  1   . 
         FIG.  3    is a cross-sectional view showing a first thermally conductive adhesive infilled into the groove of  FIG.  2   . 
         FIG.  4    is a cross-sectional view showing a first thermally conductive sheet attached to the first thermally conductive adhesive of  FIG.  3   . 
         FIG.  5    is a cross-sectional view of a second substrate according to an embodiment of the present disclosure. 
         FIG.  6    is a cross-sectional view of an adhesive film according to an embodiment of the present disclosure. 
         FIG.  7    is a cross-sectional view showing a first substrate of  FIG.  4   , the adhesive film of  FIG.  6   , and the second substrate of  FIG.  5    which are placed in sequence. 
         FIG.  8    is a cross-sectional view showing the first substrate, the adhesive film, and the second substrate of  FIG.  7    which are pressed together. 
         FIG.  9    is a cross-sectional view of a circuit board. 
         FIG.  10    is a cross-sectional view showing a protective layer formed on the circuit board of  FIG.  9   . 
         FIG.  11    is a cross-sectional view showing a connecting sheet connected to a bus bar of the circuit board of  FIG.  10   . 
         FIG.  12    is a cross-sectional view showing a monitoring element connected to a fuse of the circuit board of  FIG.  11   . 
         FIG.  13    is a cross-sectional view showing adhesive layers bonded to a first copper block and a second copper block of the circuit board of  FIG.  12   . 
         FIG.  14    is a cross-sectional view of a battery assembly according to an embodiment of the present disclosure. 
         FIG.  15    is a cross-sectional view of a battery module formed by connecting two of the battery assemblies of  FIG.  14   . 
         FIG.  16    is a cross-sectional view of a battery module including a bracket according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts may be exaggerated to better illustrate details and features of the present disclosure. 
     Several definitions that apply throughout this disclosure will now be presented. 
     The term “coupled” is defined as connected, whether directly or indirectly through intervening components, and is not necessarily limited to physical connections. The connection can be such that the objects are permanently connected or releasably connected. The term “substantially” is defined to be essentially conforming to the particular dimension, shape, or other feature that the term modifies, such that the component need not be exact. For example, “substantially cylindrical” means that the object resembles a cylinder, but can have one or more deviations from a true cylinder. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series, and the like. 
     Referring to  FIGS.  1  to  14   , a method for manufacturing a battery assembly  100  is illustrate. The method includes steps as follows. 
     Step S1, referring to  FIGS.  1  to  4   , a first substrate  20  is provided. The first substrate  20  includes a first copper layer  24 , a first dielectric layer  22 , and a plurality of thermally conductive adhesive blocks  25 . The first dielectric layer  22  is disposed on a surface of the first copper layer  24 , and the thermally conductive adhesive blocks  26  penetrate the first dielectric layer  22  and are coupled to the first copper layer  24 . 
     The first dielectric layer  22  is made of a flexible material, which is selected from a group consisting of polyimide, liquid crystal polymer, modified polyimide, and any combination thereof. In this embodiment, a material of the first dielectric layer  22  is polyimide. 
     In some embodiments, the first substrate  20  further includes a plurality of first thermally conductive sheets  26 . The first thermally conductive sheets  26  is disposed on surfaces of the first thermally conductive adhesives  25  facing away from the first copper layer  24 . The first thermally conductive adhesives  25  are spaced apart from each other, the first thermally conductive sheets  26  are also spaced apart from each other, which is convenient for bending in the subsequent manufacturing process. 
     The first thermally conductive sheets  26  are made of a material with good thermal conductivity, which includes, but is not limited to, metal or carbon materials. In this embodiment, a material of the first thermally conductive sheets  26  is copper. 
     In some embodiments, the first substrate  20  is formed by the following steps. 
     Step S101, referring to  FIG.  1   , a single-sided copper clad laminate  21  is provided. The single-sided copper clad laminate  21  includes the first dielectric layer  22  and the first copper layer  24  on a surface of the first dielectric layer  22 . 
     Step S102, referring to  FIG.  2   , parts of the first dielectric layer  22  are removed to form a plurality of grooves  23  which expose a surface of the first copper layer  24 . 
     The grooves  23  penetrate the first dielectric layer  22  along a stacking direction of first copper layer  24  and the first dielectric layer  22 . Positions of the grooves  23  are related to positions of cavities to be formed subsequently. 
     Step S103, referring to  FIG.  3   , the first thermally conductive adhesives  25  are infilled into the grooves  23 . 
     Step S104, referring to  FIG.  4   , the first thermally conductive sheets  26  are attached to surfaces of the first thermally conductive adhesives  25 . 
     Step S2, referring to  FIG.  5   , a second substrate  30  is provided. The second substrate  30  includes a second copper layer  34 , a second dielectric layer  32 , and at least one second thermally conductive adhesive  35 . The second dielectric layer  32  is on a surface of the second copper layer  34 , and the second thermally conductive adhesive  35  penetrates the second dielectric layer  32  and is coupled to the second copper layer  34 . 
     The second dielectric layer  32  is made of a flexible material. 
     Thicknesses of the first dielectric layer  22  and the second dielectric layer  32  are 1.25 µm to 25 µm, which is convenient for bending in the subsequent manufacturing process. 
     In some embodiments, the second substrate  30  further includes at least one second thermally conductive sheet  36 . The second thermally conductive sheet  36  is on a surface of the second thermally conductive adhesive  35  facing away from the second copper layer  34 . The second thermally conductive sheet  36  corresponds in position to at least one of the first thermally conductive sheet  26 . A material of the second thermally conductive sheet  36  includes, but is not limited to, metal or carbon materials. 
     The second substrate  30  can be manufactured by steps 
     The steps of forming the second substrate  30  may be substantially the same as the steps of forming the first substrate  20 . The second substrate  30  may also be formed by other methods. 
     Step S3, referring to  FIG.  6   , an adhesive film  40  is provided. The adhesive film  40  includes a plurality of through holes  42 . The through holes  42  corresponds in position to the first thermally conductive adhesives  25 . 
     Step S4, referring to  FIGS.  7  and  8   , the first substrate  20  and the second substrate  30  are pressed onto opposite sides of the adhesive film  40  to seal the through holes  42  to form cavities  45   a , thereby forming a plurality of heat dissipation areas I and a plurality of bending area II which are arranged at intervals in turn. 
     In a stacking direction of the first substrate  20 , the adhesive film  40 , and the second substrate  30 , areas of the stacked structure including the first substrate  20 , the adhesive film  40 , and the second substrate  30  corresponding to the first thermally conductive adhesives  25  and/or the second thermally conductive adhesive  35  are the heat dissipation areas I, and one bending area II is located between two adjacent heat dissipation areas I. 
     In some embodiments, the first copper layer  24  is on a surface of the first dielectric layer  22  facing away from the adhesive film  40 , the second copper layer  34  is on a surface of the second dielectric layer  32  facing away from the adhesive film  40 , the first thermally conductive sheet  26  and the second thermally conductive sheet  36  are in the through holes  42 . 
     In some embodiments, a number of the through holes  42  is greater than a number of the first thermally conductive sheet  26 , so that a plurality of cavities  45   a  and  45   b  are formed, and each bending area II includes one cavity  45   b . The cavities  45   a  and  45   b  are filled with air. Because the heat dissipation performance of air is better than that of the first dielectric layer  22  and the second dielectric layer  32 , the arrangement of the cavities  45   a  and  45   b  can improve the heat dissipation performance. On the other hand, the arrangement of the cavities  45   b  is convenient for bending in the subsequent manufacturing process. 
     In some embodiments, the cavities  45   a  can also be filled with liquid, such as water, to further improve the heat dissipation efficiency. 
     In some embodiments, the number of cavities  45   a  or  45   b  located in one heat dissipation area I or one bending area II is not limited to one, but can also be multiple, and multiple cavities  45   a  or  45   b  are spaced through the adhesive film  40 . A distance between two adjacent cavities  45   a  or  45   b  in one heat dissipation area I or one bending area II is greater than or equal to 1 mm. Since there will be glue overflow in the subsequent pressing process, a certain space for glue overflow is reserved. 
     A thickness of the adhesive film  40  is 100 µm to 300 µm, so that the first dielectric layer  22  and the second dielectric layer  32  will not be connected due to too close distance in the subsequent bending process. 
     Step S5, referring to  FIG.  9   , the first copper layer  24  is etched to form bus bars  242  and a first copper block  245 , and the second copper layer  34  is etched to form fuses  342  and a second copper block  345 , thereby forming a circuit board  10 . 
     The first copper layer  24  and the second copper layer  34  in the bending areas II are removed to facilitate the bending of the bending areas II in the subsequent process. 
     Portions of the first copper layer  24  and the second copper layer  34  in the heat dissipation areas I are removed by etching. The bus bars  242  are electrically coupled to a battery cell  70  (shown in  FIG.  14   ). The fuses  342  are electrically coupled to the battery cell  70 . When a certain threshold value is exceeded, the fuses  342  blocks the current in the battery cell  70  to protect the battery cell  70 . The first copper block  245  and the second copper block  345  are in contact with the battery cell core  70 , so that the heat generated by the battery cell  70  can be quickly transferred. 
     A thickness of the first copper layer  24  is greater than or equal to 35 µm, so that current after confluence can be in a preset range. 
     In some embodiments, referring to  FIG.  10   , the method further includes a step of forming protective layers  47 . The protective layers  47  are located at the peripheries of the bus bars  242  and the fuses  342  to protect the bus bars  242  and the fuses  342 . 
     Step S6, referring to  FIGS.  11  to  14   , the bending areas II of the circuit board  10  are bent to form a holding groove  60 , and the battery cell  70  is placed in the holding groove  60  and is electrically connected with the bus bars  242 , thereby forming a battery assembly  100 . 
     In some embodiments, step S6 includes the following steps. 
     Step S601, referring to  FIG.  11   , connecting sheets  52  are connected to surfaces of the bus bars  242 . 
     The connecting sheets  52  are made of a conductive material, which includes but is not limited to nickel. 
     Step S602, referring to  FIG.  12   , monitoring elements  55  are connected to the fuses  342 . 
     The monitoring element  55  is used to monitor a working condition of the battery cell  70  and transmit a monitoring result to a battery management system (BMS) (not shown), so that the battery management system can control the working condition of a battery according to the working condition of the battery cell. 
     Step S603, referring to  FIG.  13   , adhesive layers  57  are bonded to surfaces of the first copper block  245  and the second copper block  345 . 
     The adhesive layers  57  can be made of any adhesives, such as curing adhesive. 
     Step S604, referring to  FIG.  14   , both ends of the circuit board  10  are bent toward a side where the connecting sheets  52  are located to form the holding groove  60 . 
     The bending areas II are bent, the connecting sheets  52  and the first copper block  245  face and enclose the holding groove  60 , and the fuses  342  and the second copper block  345  are on a side of the second dielectric layer  32  facing away from the holding groove  60 . 
     Step S605, referring to  FIG.  14   , the battery cell  70  is placed in the holding groove  60 , and the battery cell  70  is coupled to the circuit board  10  through the connecting sheets  52 , thereby forming the battery assembly  100 . 
     The first copper block  245  facing the holding groove  60  is coupled to the battery cell  70  through one adhesive layer  57 , so that the battery cell  70  is fixed in the holding groove  60 . The second copper block  345  facing away from the holding groove  60  is coupled to another one battery cell  70  to transfer heat away from the battery cell  70 . The arrangement of the first copper block  245  and the second copper block  345  increase a contact area between the battery cell  70  and the circuit board, thereby improving the heat dissipation performance. 
     Referring to  FIG.  14   , the battery assembly  100  is illustrated. The battery assembly  100  includes at least one circuit board  10  and at least one battery cell  70 . The circuit board  10  defines a holding groove  60 , the battery cell  70  is accommodated in the holding groove  60  and is electrically connected to the circuit board  10 . The battery cell  70  includes a positive tab (not shown) and a negative tab (not shown) which are electrically coupled to the circuit board  10 . 
     The circuit board  10  includes the heat dissipation areas I and the bending areas II which are connected in turn and are alternately arranged. The heat dissipation areas I and the bending areas II enclose the holding groove  60 , and the bending areas II correspond in position to corner areas of the battery cell  70 . 
     The circuit board  10  includes the first dielectric layer  22 , the second dielectric layer  32 , the adhesive film  40 , the fuses  342 , the bus bars  242 , the first copper block  245 , and the second copper block  345 . 
     The first dielectric layer  22  and the second dielectric layer  32  are made of a flexible material selected from a group consisting of polyimide, liquid crystal polymer, modified polyimide, and any combination thereof. 
     The adhesive film  40  is located between the first dielectric layer  22  and the second dielectric layer  32 . The adhesive film  40  is bonded to and supports the first dielectric layer  22  and the second dielectric layer  32 , so that the cavities  45   a  are formed between the first dielectric layer  22  and the second dielectric layer  32 . 
     The cavities  45   a  are at least located in the heat dissipation areas I, and the cavities  45   a  are filled with air. Since the heat dissipation performance of air is better than that of the first dielectric layer  22  and the second dielectric layer  32 , the arrangement of the cavities  45   a  can improve the heat dissipation performance and reduce a weight of the battery assembly  100 . In some embodiments, the cavities  45   a  can also be filled with liquid, such as water, to further improve the heat dissipation efficiency. 
     In some embodiments, the cavities  45   b  are formed between the first dielectric layer  22  and the second dielectric layer  32  in the bending areas II, which is convenient for bending in the process of forming the battery assembly  100 . 
     In some embodiments, the number of cavities  45   a  or  45   b  located in one heat dissipation area I or one bending area II is not limited to one, but can also be multiple, and multiple cavities  45   a  or  45   b  are spaced through the adhesive film  40 . 
     The bus bars  242  and the first copper block  245  are located on the surface of the first dielectric layer  22  facing away from the second dielectric layer  32 , and the fuses  342  and the second copper block  345  are located on the surface of the second dielectric layer  32  facing away from the first dielectric layer  22 . The fuses  342 , the bus bars  242 , the first copper block  245 , and the second copper block  345  are all located in the heat dissipation areas I. 
     The bus bars  242  correspond in position to the positive tab and the negative tab of the battery cell  70 , so as to facilitate the electrical connection between the circuit board  10  and the battery cell  70 . 
     In some embodiments, the battery assembly  100  further includes the connecting sheets  52 . The connecting sheets  52  are located on surfaces of the bus bars  242  facing the battery cell  70  and electrically connect the bus bars  242  and the battery cell  70 . 
     The fuses  342  are on a surface of the second dielectric layer  32  facing away from the bus bars  242 . In the same area, the position of the fuse  342  corresponds to the position of the busbar  242 . 
     The second thermally conductive sheet  36  is not disposed on the surface of the second dielectric layer  32  facing away from the fuses  342  in the heat dissipation area I, which can prevent the heat from transferring to the fuses  342  and causing the fuses  342  to overheat. 
     The first block copper  245  is connected to a surface of the battery cell  70 , so that heat from the battery cell  70  can be transferred quickly. In some embodiments, the adhesive layer  57  is disposed between the first copper block  245  and the battery cell  70 . The adhesive layer  57  connects the first copper block  245  and the battery cell  70 . The adhesive layer  57  is elastic and can play a buffering role. 
     The second copper block  345  is located on a surface of the second dielectric layer  32  facing away from the battery cell  70 . The heat generated by the battery cell  70  is transferred through the first copper block  245 , the cavities  45 , and the second copper block  345 . The second copper block  345  is coupled to a surface of another one battery cell  70  to transfer heat away from the battery cell  70 . 
     The first copper block  245  and the first thermally conductive sheet  26  can be bonded by the first thermally conductive adhesive  25 . The second copper block  345  and the second thermally conductive sheet  36  can be bonded by the second thermally conductive adhesive  35 . 
     In some embodiment, the battery assembly  100  further includes the first thermally conductive sheet  26  and the second thermally conductive sheet  36 . The first thermally conductive sheet  26  is located a surface of the first dielectric layer  22  facing the cavity  45   a . The second thermally conductive sheet  36  is located on a surface of the second dielectric layer  32  facing the cavity  45   a . 
     Thickness of the first thermally conductive sheet  26  and the second thermally conductive sheet  36  are 25 µm to 50 µm, so that the cavities  45   a  and  45   b  can have a certain flexibility and the circuit board  10  can be bent during the manufacturing process. 
     In some embodiments, the battery assembly  100  further includes monitoring elements  55 . The monitoring elements  55  and the fuses  342  are on the same surface of the second dielectric layer  32 , the monitoring elements  55  are coupled to the fuses  342 . 
     Referring to  FIGS.  15  and  16   , a battery module  200  according to an embodiment is illustrated. The battery module  200  includes at least two battery assemblies  100 , two adjacent battery cells  70  are spaced through the circuit board  10 . The second copper block  345  of one battery assembly  100  is connected with a surface of the battery cell  70  of another battery assembly  100  of the two adjacent battery assemblies  100 . 
     In some embodiments, the battery module  200  further includes a bracket  210  for fixing the battery assembly  100 . 
     The busbars  242 , fuses  342 , and other components are all arranged on the same circuit board  10 , which can save the space required for additional busbar and fuse  342 . The battery cell  70  is surrounded by the circuit board  10  from different directions, so that heat generated by the battery cell  70  can be transferred quickly. Moreover, the arrangement of the first copper block, the second copper block, and the cavities  45   a  in the circuit board  10  further improves the heat dissipation efficiency of the circuit board  10 , ensuring the working condition of the battery assembly  100 . 
     While the present disclosure has been described with reference to particular embodiments, the description is illustrative of the disclosure and is not to be construed as limiting the disclosure. Therefore, those of ordinary skill in the art can make various modifications to the embodiments without departing from the scope of the disclosure as defined by the appended claims.