Patent Publication Number: US-2023155186-A1

Title: Battery pack

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation application based on pending application No. 17/095,836, filed Nov. 12, 2020, the entire contents of which is hereby incorporated by reference. 
     Korean Patent Application No. 10-2019-0160736, filed on Dec. 5, 2019, in the Korean Intellectual Property Office, and entitled: “Battery Pack,” is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     1. Field 
     Embodiments relate to a battery pack. 
     2. Description of the Related Art 
     Secondary batteries may be charged and discharged, unlike primary batteries, which are not rechargeable once discharged. Low-capacity secondary batteries may be used in portable small-sized electronic devices, e.g., a mobile phone, a camcorder, and the like, and high-capacity secondary batteries may be used as an energy source, e.g., for driving a motor for a hybrid car or the like. 
     The secondary battery may be manufactured in various shapes, e.g., a cylindrical, prismatic, or pouch type, The secondary battery may be configured such that an electrode assembly formed by interposing a separator as an insulator between a positive electrode plate and a negative electrode plate and accommodated in a case with an electrolyte solution, and a cap plate is installed in the can. Positive and negative electrode terminals may be connected to the electrode assembly and may be exposed and protruded to the outside through the cap plate. 
     A plurality of secondary batteries may be connected in series, in parallel or in series/parallel, forming a battery pack having an increased high output, which may be used in various fields. 
     SUMMARY 
     Embodiments are directed to a battery pack including a plurality of battery cells; a first case accommodating the plurality of battery cells; a protection circuit module coupled to one side of the plurality of battery cells and electrically connecting the plurality of battery cells; a bus bar electrically connected to the protection circuit module and extending in one direction along the plurality of battery cells; and a second case coupled to the first case and accommodating the plurality of battery cells, the protection circuit module, and the bus bar, wherein the bus bar includes a diverged branch formed by cutting a region of the bus bar in the one direction. 
     The diverged branch may be formed by cutting an inner region of the bus bar to space regions apart in a widthwise direction perpendicular to the one direction. 
     The diverged branch may be branched off at one side of the bus bar relative to a center of the bus bar relative to the one direction. 
     Relative to the center of the bus bar in the one direction, the diverged branch may be cut from a region adjacent to a midpoint between the center and an end of the bus bar. 
     The diverged branch may be branched off by a slit cut in the one direction. 
     The diverged branch may be an output terminal for an external circuit. 
     The battery pack may further include a voltage sensor coupled to an end of the bus bar that is adjacent to the diverged branch. 
     The battery pack may further include case holders between the first case and the second case to fix positions of the battery cells. 
     The protection circuit module may include wiring patterns overlying the plurality of battery cells and electrically connected to the plurality of battery cells. 
     The bus bar may extend along edges of the protection circuit module, and protrusions of the bus bar are coupled to coupling holes in the protection circuit module to electrically connect the protection circuit module and the bus bar. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Features will be apparent to those of skill in the art by describing in detail exemplary embodiments with reference to the attached drawings in which: 
         FIG.  1    is a perspective view of a battery pack according to an embodiment. 
         FIG.  2    is a perspective view of a state in which an upper cover is removed from the battery pack shown in  FIG.  1   . 
         FIG.  3    is an enlarged view of a portion A shown in  FIG.  2   . 
         FIG.  4    is an exploded perspective view of the battery pack according to an embodiment. 
         FIG.  5    illustrates voltages detected from various positions of a bus bar in the battery pack according to an embodiment. 
         FIG.  6    is a detailed side view of a configuration of the bus bar in the battery pack according to an embodiment. 
         FIG.  7    illustrates a cell voltage distribution depending on the load in the battery pack according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey exemplary implementations to those skilled in the art. 
     In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being “on” another layer or element, it can be directly on the other layer or element, or intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Like reference numerals refer to like elements throughout. 
     Various embodiments of the present disclosure may be embodied in many different forms and should not be construed as being limited to the example embodiments set forth herein. Rather, these example embodiments of the disclosure are provided so that this disclosure will be thorough and complete and will convey inventive concepts of the disclosure to those skilled in the art. 
     As used herein, the terms “or” and “and/or” include any and all combinations of one or more of the associated listed items. In addition, it will be understood that when an element A is referred to as being “connected to” an element B, the element A can be directly connected to the element B or an intervening element C may be present therebetween such that the element A and the element B are indirectly connected to each other. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms that the terms “include,” “including,” “comprise” and/or “comprising,” when used in this specification, specify the presence of stated features, numbers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, and/or groups thereof. 
     It will be understood that, although the terms first, second, etc. may be used herein to describe various members, elements, regions, layers and/or sections, these members, elements, regions, layers and/or sections should not be limited by these terms, and sequential inclusion of numbered elements are not required. These terms are only used to distinguish one member, element, region, layer and/or section from another. Thus, for example, a first member, a first element, a first region, a first layer and/or a first section discussed below could be termed a second member, a second element, a second region, a second layer and/or a second section without departing from the teachings of the present disclosure. 
     Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature’s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the element or feature in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “on” or “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. 
     Hereinafter, a configuration of a battery pack according to an embodiment will be described. 
       FIG.  1    is a perspective view of a battery pack according to an embodiment.  FIG.  2    is a perspective view of a state in which an upper cover is removed from the battery pack shown in  FIG.  1   .  FIG.  3    is an enlarged view of a portion A shown in  FIG.  2   .  FIG.  4    is an exploded perspective view of the battery pack according to an embodiment. 
     First, referring to  FIGS.  1  to  4   , the battery pack  10  according to an embodiment may include a first case  100 , a case holder  200 , battery cells  300 , a protection circuit module  400 , bus bars  510  and  520 , a sealing member or sealer  600 , a second case  700 , fasteners  810 , and electrode terminals  910  and  920 . 
     In an implementation, the first case  100  may be coupled to the second case  700  to accommodate the battery cells  300  in an internal space defined by the first case  100  and the second case  700 . The first case  100  may include a frame  110  defining the shape of the space accommodating the battery cells  300 , and lower holders  120 . The frame  110  may protect the battery cells  300  accommodated therein from external shocks. In an implementation, the lower holders  120  may help prevent the battery cells  300  from deviating from predetermined positions thereof by fixing lower portions of the battery cells  300 . 
     The case holder  200  may be coupled to the inside of the first case  100  and may be fixed to the inside of the frame  110  of the first case  100 . In an implementation, the case holder  200  may be basically constructed by the frame  210  and may include holes  220  corresponding to or aligned with the lower holders  120  of the first case  100 . In an implementation, the battery cells  300  fixed to the lower holders  120  of the first case  100  may pass the holes  220  of the case holder  200 , and positions of the battery cells  300  may be fixed. 
     The case holder  200  may be formed using an electrically insulating plastic material. In an implementation, the case holder  200  may be formed using, e.g., polypropylene (PP) or polyethylene (PE). 
     In an implementation, as illustrated in the drawings, the battery cells  300  may be cylindrical batteries. In an implementation, the battery cells  300  may be prismatic or atypical batteries. Lower portions of the battery cells  300  may be fixed by the lower holders  120  of the first case  100 , and side portions thereof may be fixed by passing through the holes  220  of the case holder  200 . In an implementation, upper portions of the battery cells  300  may be fixed by the protection circuit module  400  positioned thereon, and positions of the battery cells  300  may be fixed in a state in which they are spaced apart from one another. The cell cases  310  including the lower portions of the battery cells  300  may have a first polarity, and an upwardly protruding cap-up  320  of each of the battery cells  300  may have a second polarity. In an implementation, the first polarity may be a positive polarity and the second polarity may be a negative polarity, or vice versa. The protection circuit module  400  coupled to the upper portions of the battery cells  300  may be connected to the cell cases  310  of the battery cells  300  and the cap-ups  320  through internal wiring patterns  410 . In an implementation, the battery cells  300  arranged in such a manner may be electrically connected in various manners including, e.g., in series, in parallel, or in series/parallel, as desired. 
     The protection circuit module  400  may be coupled to the upper portions of the battery cells  300  and may be covered by the second case  700 . The protection circuit module  400  may be basically constructed by an insulating circuit board and may include the wiring patterns  410  corresponding to the battery cells  300 . In an implementation, each of the wiring patterns  410  may include a cell-exposing inner wall  411  including a plurality of holes inwardly formed in the protection circuit module  400 , and a first wiring pattern  412  and a second wiring pattern  413  formed throughout the cell-exposing inner wall  411 . In an implementation, the cell-exposing inner wall  411  may correspond to or overlie each of the positions of the battery cells  300 , and the cap-up  320  of each of the battery cells  300  may be positioned inside the cell-exposing inner wall  411 . In an implementation, the first wiring pattern  412  and the second wiring pattern  413  may correspond to (e.g., may be provided at) each of the battery cells  300 , and may be electrically connected to the cell case  310  and the cap-up  320  of each of the battery cells  300 , respectively. In an implementation, the first wiring pattern  412  may be connected to the cell case  310  of the battery cell  300  to have a first polarity, and the second wiring pattern  413  may be connected to the cap-up  320  of the battery cell  300  to have a second polarity. In an implementation, the first wiring patterns  412  and the second wiring patterns  413  may be connected in a connection mode as desired, e.g., in series, in parallel or in series/parallel, within the protection circuit module  400 . In an implementation, the battery cells  300  may be electrically connected to one another and may output a desired level of current or voltage. 
     The protection circuit module  400  may further include coupling holes  414  at edges thereof, and coupling protrusions  511  and  521  along edges of the bus bars  510  and  520 , which will be described below, may pass through and be engaged with the coupling holes  414 . In an implementation, a coupled state of the bus bar  510  and the protection circuit module  400  may be stably maintained. In an implementation, the protection circuit module  400  may be electrically connected to the coupling holes  414 . In an implementation, the bus bars  510  and  520  may be electrically coupled to the protection circuit module  400  and may be electrically connected to the battery cells  300  connected to the protection circuit module  400 . 
     The bus bars  510  and  520  may be made of an electrically conductive material and may be at opposite edges of the protection circuit module  400  along the lengthwise direction of the protection circuit module  400 . The bus bars  510  and  520  may receive voltages of first and second polarities from the protection circuit module  400 . In an implementation, the bus bars  510  and  520  may receive voltages of various positions of the protection circuit module  400  along the lengthwise direction. 
     Lengthwise opposite ends of the first bus bar  510  may be defined as a first end  510   a  that is relatively far from or distal to a voltage sensing terminal, and a second end  510   b  that is relatively close to or proximate to the voltage sensing terminal, respectively. The second bus bar  520  may also have opposite ends corresponding or analogous to those of the first bus bar  510 . 
     In an implementation, when an output terminal is connected to or via a midpoint C2 of the bus bars  510  and  520 , which will be described below, a more accurate average voltage of the battery cells  300  may be sensed from the voltage sensing terminal. A specific connection relationship between the bus bars  510  and  520  will be described below. 
     The sealer  600  may be between the first case  100  and the second case  700 . The sealer  600  may be an elastic member made of an electrically insulating material. In an implementation, the sealer  600  may be a silicon or rubber member or gasket between coupling positions of the two cases  100  and  700  to seal the two cases  100  and  700  to each other. 
     The second case  700  may be coupled to the first case  100  on top of the first case  100 . In an implementation, the second case  700  coupled to the first case  100  may protect internal components, including the battery cells  300 , the protection circuit module  400 , and so on. The second case  700  may have a planar shape, like the first case  100 , and may be coupled to the first case  100  with the sealer  600  positioned therebetween. 
     In an implementation, the second case  700  may include a plurality of fastening holes  710  spaced apart from one another along the edges thereof, and the second case  700  may be fastened with the first case  100  as the fasteners  810  pass through the fastening holes  710  from above. In an implementation, according to the types of the first case  100  and the second case  700 , the first case  100  and the second case  700  may also be coupled to each other without the fastening holes  710  and the fasteners  810 . In an implementation, when the first case  100  and the second case  700  may be coupled to each other by hook coupling, and the fastening holes  710  or the fasteners  810  may not be separately provided. 
     The fasteners  810  may include a plurality of fasteners corresponding to the fastening holes  710  of the second case  700 . The fasteners  810  may pass through the fastening holes  710  of the second case  700  from above to reach the first case  100  below the second case  700 . In an implementation, the coupling force between the first case  100  and the second case  700  may be maintained through threads. In an implementation, as described above, the coupling of the first case  100  and the second case  700  without the fasteners  810  may also be achieved. 
     The electrode terminals  910  and  920  may be coupled to the bus bars  510  and  520 , respectively, and may be exposed to one side of the case holder  200  and the first case  100 . The electrode terminals  910  and  920  may include a first electrode terminal  910  and a second electrode terminal  920 , which include first terminal members  911  and  921 , second terminal members  912  and  922 , third terminal members  913  and  923 , and fourth terminal members  914  and  924 , respectively. 
     The first electrode terminal  910  will now be described by way of example. The first terminal member  911  may be connected to one end of the first bus bar  510  to receive a final voltage, the second to fourth terminal members  912  to  914  may be sequentially coupled to the first terminal member  911 , and the fourth terminal member  914  may be finally exposed out of the first case  100 . In an implementation, the second electrode terminal  920  may also be connected to the second bus bar  520 , and the fourth terminal  924  may be finally exposed out of the first case  100 . Therefore, an external circuit coupled to the battery pack  10  may be electrically connected through the fourth terminal members  914  and  924 , respectively. 
     Hereinafter, a configuration of a bus bar and detected voltages in the battery pack according to an embodiment will be described in greater detail. 
       FIG.  5    illustrates voltages detected from various locations of a bus bar in the battery pack according to an embodiment.  FIG.  6    is a detailed side view of a configuration of the bus bar in the battery pack according to an embodiment. 
     First, referring to  FIG.  5   , voltages v1 and v2 are indicated on the basis of or at a location on the first bus bar  510  at different positions thereof from the first end  510   a  to the second end  510   b . The second bus bar  520  may also be shaped to correspond to the first bus bar  510 . However, for brevity, the voltages are shown and described on the basis of a distance between the first end  510   a  and the second end  510   b  of the bus bar  510 . 
     A voltage sensor may be coupled to the second end  510   b  of the first bus bar  510 , and the second end  510   b  may serve as a voltage sensing terminal of a battery pack. The voltage sensor may be a sensor for sensing the overall voltage of the battery pack, and it may be difficult to install the voltage sensor within the battery pack. In an implementation, the voltage sensor may be coupled to one end of the battery pack. In an implementation, the voltage sensor may be coupled to the second end  510   b . 
     Assuming that the distance between the first end  510   a  and the second end  510   b  is 1 (e.g., 1 arbitrary unit),  FIG.  5    shows the voltage v1 applied to the first bus bar  510  in a section between the first end  510   a  to the second end  510   b  and the voltage v2 applied to the second bus bar  520 . A voltage difference (v1-v2) between the first bus bar  510  and the second bus bar  520 , which is obtained from the voltage v1 applied to the first bus bar  510  and the voltage v1 applied to the first bus bar  510 , may also be so distributed as shown in  FIG.  5   . In an implementation, as shown in  FIG.  5   , the voltage difference (v1-v2) may gradually decrease from the first end  510   a  along the lengthwise direction of the first bus bar  510 . In an implementation, the voltage difference (v1-v2) between the opposite ends of the bus bar  510  may be a minimum value at a two thirds (⅔) point of the overall length, starting from the first end  510   a , e.g., a one third (⅓) point from the second end  510   b , and may increase after passing the point. In an implementation, as shown in  FIG.  5   , when the region between the first end  510   a  to the second end  510   b  is divided into about three sections, a maximum voltage of the battery pack may appear at the first end  510   a , and a minimum voltage of the battery pack may appear at the two thirds (⅔) point. In addition, the average voltage of the battery pack having the battery cells  300  may appear at a point being between the first end  510   a  and the second end  510   b , e.g., a one third (⅓) point from the first end  510   a . In an implementation, the average voltage of the battery pack  10  may also appear at the second end  510   b . 
     Referring to  FIG.  6   , the specific configuration of the first bus bar  510  for achieving the above is shown. As shown in  FIG.  6   , assuming that the overall length of the first bus bar  510  from first end portion  510   a  to the second end portion  510   b  is denoted by L1, the first bus bar  510  may include a diverged branch  510   c  located at about the ⅔ point from the first end  5   10   a . The diverged branch  510   c  may be a branch off from the first bus bar  510 , e.g., through or due to the presence of a cutting hole  510   e  (e.g., slit) cut to a cut portion or divergence point  510   d  located at about the ⅔ point from the first end  510   a . 
     In an implementation, the cutting hole  510   e  may be in the form of a slit produced by cutting into the first bus bar  510  from the second end  510   b  (e.g., in a region closer to a midpoint C2 than to a center C1 of the first bus bar  510 ) in the lengthwise direction. The midpoint C2 may be a midpoint between the center C1 and the second end  510   b  of the first bus bar  510 . In an implementation, a length L2 from the divergence point  510   d  to the second end  510   b  may be about one third ⅓ of the overall length L1. 
     In an implementation, an output terminal may be connected to the diverged branch  510   c  (e.g., at the circular hole therein), and outputs of the battery pack  10  according to the embodiment may be applied to an external circuit. In an implementation, the second bus bar  520  may also include a diverged branch located to correspond to the first bus bar  510  to apply outputs of first and second polarities, e.g., B+ and B-, to the external circuit. 
     In an implementation, referring to  FIGS.  5  and  6   , divergence for outputting may be made at the divergence point  510   d , which may correspond to about the ⅔ point of the overall length L1 of the bus bars  510  and  520 , using the diverged branches of the bus bars  510  and  520 , and the voltage may be lowest at the divergence point  510   d . Accordingly, the bus bars  510  and  520  according to the present disclosure may have a voltage distribution as shown in  FIG.  5   . In an implementation, the average voltage of the maximum voltage at the first end  510   a  of the bus bar  510  and the minimum voltage at the divergence point  510   d  of the bus bar  510  may be at the second end  510   b  of the bus bar  510 , and the voltage sensor installed at the second end  510   b  of the bus bar  510  may accurately sense the average voltage of the battery pack  10 . 
     In an implementation, with diverged branch structures of the bus bars  510  and  520 , voltage differences at various regions may be minimized. In other bus bars without a diverged branch structure, e.g., an output of a battery pack may be applied from one-side end of the bus bar, and the voltage of an output from the output end may be lowest, increasing a voltage difference between the output end portion and an end portion having the maximum voltage, which is opposite to the output end. Therefore, potential differences between opposite ends in the bus bars  510  and  520  may be increased, resulting in a voltage imbalance. 
     In the battery pack  10  according to the embodiment of the present disclosure, as shown in  FIG.  5   , a difference between the maximum voltage at the first end  510   a  and the minimum voltage at the divergence point  510   d  from which the diverged branch  510   c  starts may be minimized by forming the diverged branch  510   c  at the ⅔ point of the overall length from the first end portion  510   a . Voltage imbalance issues may be minimized. 
     Hereinafter, a voltage distribution in the battery pack according to an embodiment will be described. 
       FIG.  7    illustrates a cell voltage distribution depending on the load in the battery pack according to an embodiment. 
     Referring to  FIG.  7   , it may be that the temperature of the battery pack  10  may be highest at about a ⅔ point to which the output terminal is connected, and the temperature may gradually decrease toward opposite sides away from the ⅔ point. In an implementation, as shown in  FIG.  7   , it may be seen that when the output terminals shown in  FIG.  5    are connected to the battery pack  10 , the temperature of the battery pack  10  may be highest at points to which the outputs B+ and B- are applied, and the temperatures may gradually decrease after passing the points. In an implementation, as shown in  FIG.  7   , the temperature distribution may be generally uniformly maintained in view of the output points. Thus, it may be seen from the temperature distribution of the battery pack  10  that a temperature imbalance may be compensated for in a similar manner to that of the voltage distribution. 
     By way of summation and review, a battery pack may output high power, a voltage or temperature balance between the battery cells in the battery pack may be maintained. 
     One or more embodiments may provide a battery pack including a plurality of battery cells connected to one another, which is capable of accurately sensing an output voltage and compensating for a voltage imbalance at a bus bar. 
     As described above, the battery pack according to the present disclosure may include output terminals connected to each other by forming the diverging branch extending from the central region of the bus bar, thereby accurately sensing the output voltage at an end of the bus bar and maintaining voltage and temperature balances. 
     Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.