Patent Publication Number: US-11658358-B2

Title: Pouch case, and secondary battery and secondary battery pack using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/368,047 filed on Mar. 28, 2019 and issued as U.S. Pat. No. 11,056,734 B2 on Jul. 6, 2021, which claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2018-0037661, filed on Mar. 30, 2018, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The following disclosure relates to a pouch case, and a secondary battery and a secondary battery pack using the same, and more particularly, to a pouch case configured in such a way that a perfect cooling structure is formed on one side surface of a secondary battery using the pouch case and one side surface of the secondary battery is held close to the cooling plate to maximize cooling efficiency and to have high energy density, and a secondary battery and a secondary battery pack using the same. 
     BACKGROUND 
     In general, a lithium secondary battery is classified into a can type secondary battery in which an electrode assembly is installed in a metallic can, and a pouch type secondary battery in which an electrode assembly is installed in a pouch of an aluminum laminate sheet, according to a shape of a case. 
     Lithium secondary batteries have been widely used in a medium and large size device such as a vehicle or a power storage device as well as a small size mobile device. In this case, to increase capacitance and output, a plurality of pouch type secondary batteries that are easily stacked and have a low weight are connected and used. 
     However, when a plurality of pouch type secondary batteries are stacked to configure a battery module, heat generated from the plurality of secondary batteries are combined to rapidly increase a temperature of a battery module, and thus, when the battery module is configured using the plurality of pouch type secondary batteries, it is very important to ensure stable and effective cooling performance. 
     Accordingly, as a cooling method having a simple structure while ensuring effective cooling performance, research has been conducted on a method of cooling a side surface portion of a pouch type secondary battery via direct surface contact with a cooling plate, but thus far, it is difficult to effectively hold a side surface portion of a pouch type secondary battery close to a cooling plate due to limitations of a shape of a pouch case. 
       FIG.  1    is an exploded perspective view of a pouch type secondary battery according to the conventional art. 
     Referring to  FIG.  1   , a pouch case  10  according to the conventional art configured to provide an accommodation space for accommodating an electrode assembly  20  therein includes a pair of accommodation portions that are formed as independent spaces, and each of the pair of accommodation portions has a width and a length, which correspond to the width and the length of the accommodated electrode assembly  20 , respectively, and the sum of the depths of the pair of accommodation portions approximately corresponds to the thickness of the electrode assembly  20 . 
     However, the pouch type secondary battery according to the conventional art has one side surface portion except for three side surfaces that seal the pouch case  10 , on which a concave line is formed in a length direction of a side surface. As such, due to the concave line formed on the side surface portion of the secondary battery, there is a problem in that it is difficult to effectively bring the side surface portion of the secondary battery into contact with the cooling plate and cooling efficiency is degraded. 
     To overcome the above problem, Patent Document 1 discloses that a pair of accommodation portions is formed as one space in a pouch case rather than being separated as independent spaces. However, even if the pouch case with such shape is used, when an electrode assembly is packaged, it is not easy to fold the case and it is difficult to uniformly form a side surface portion of a secondary battery, which contacts a cooling plate. 
     CITED REFERENCE 
     Patent Document 
     
         
         Patent Document 1: Korean Patent Laid-Open Publication No. 10-2007-0102768 
       
    
     SUMMARY 
     An embodiment of the present disclosure is directed to providing a pouch case configured in such a way that a cooling structure is formed on one side surface of a secondary battery using the pouch case and one side surface of the secondary battery is held close to a cooling plate to maximize cooling efficiency and to have high energy density, and a secondary battery and a secondary battery pack using the same. 
     Another embodiment of the present disclosure is directed to providing a pouch case configured in such a way that a side surface portion of a secondary battery is formed to be flat rather than to protrude, and thus, a relatively small space is occupied with respect to the same battery capacitance to have high energy density, and a secondary battery and a secondary battery pack using the same. 
     The present disclosure is not limited to the above objects, and additional objects of the present disclosure will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the present disclosure. 
     In one general aspect, a pouch case for accommodating and packaging an electrode assembly including a plurality of electrodes that are stacked with a separator interposed therebetween includes: first and second accommodation portions formed to accommodate the electrode assembly; a sealing portion formed along an outer part of the pouch case to surround the first and second accommodation portions; and a connecting portion formed with the same depth as that of the first and second accommodation portions and configured to connect the first and second accommodation portions at a predetermined interval, wherein a protrusion protrudes in a direction toward the sealing portion at opposite ends of the connecting portion. 
     In the pouch case according to the present disclosure, the protrusion may include a top portion formed with a predetermined height on a bottom surface of the connecting portion; and an inclination portion formed to be inclined toward a bottom surface of the connecting portion at one end of the top portion. 
     In the pouch case according to the present disclosure, the inclination portion may be connected to the top portion and the bottom surface of the connecting portion with a predetermined radius of curvature. 
     In the pouch case according to the present disclosure, the top portion may be formed with the same height as that of the sealing portion. 
     In the pouch case according to the present disclosure, the first accommodation portion and one side of the connecting portion may be connected to each other along a first bent line, the second accommodation portion and the other side of the connecting portion may be connected to each other along a second bent line, and the pouch case may be bent along the first and second bent lines to accommodate the electrode assembly. 
     In the pouch case according to the present disclosure, the first and second bent lines may be spaced apart from each other by a distance corresponding to a thickness of the electrode assembly. 
     In another general aspect, a secondary battery includes: the pouch case as described above; and the electrode assembly including the plurality of electrodes that are stacked with the separator interposed therebetween, wherein the pouch case accommodates and packages electrode assembly in an accommodation space formed by folding the sealing portions to allow the first and second accommodation portions to face each other. 
     In the secondary battery according to the present disclosure, the connecting portion may be configured to uniformly form a side surface of the packaged secondary battery, and the sealing portion may include an extension portion protruding by a predetermined length in a perpendicular direction to a side surface of the secondary battery at a portion adjacent to opposite end portions of the side surface of the secondary battery. 
     In another general aspect, a secondary battery pack includes: one or more of the secondary batteries as described above; and a cooling plate including a first side surface, a second side surface facing the first side surface, and an upper surface, which surface-contacts the side surface portion of the one or more secondary batteries. 
     In the secondary battery pack according to the present disclosure, the connecting portion may be configured to uniformly form a side surface of the packaged secondary battery, and the sealing portion may include an extension portion protruding by a predetermined length in a perpendicular direction to a side surface of the secondary battery at a portion adjacent to opposite end portions of the side surface of the secondary battery. 
     In the secondary battery pack according to the present disclosure, a width between the first and second side surfaces of the cooling plate may correspond to a length of the connecting portion of the secondary battery. 
     In the secondary battery pack according to the present disclosure, a width between the first and second side surfaces of the cooling plate may be larger than a length of the connecting portion of the secondary battery. 
     In the secondary battery pack according to the present disclosure, a step difference may be formed with a height equal to or larger than the predetermined length of the extension portion of the secondary battery on each of the first and second side surfaces of the cooling plate. 
     In the secondary battery pack according to the present disclosure, one or more grooves may be formed with a depth equal to or larger than the predetermined length of the extension portion to accommodate the extension portion of the secondary battery on each of the first and second side surfaces of the cooling plate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an exploded perspective view of a secondary battery according to the conventional art. 
         FIG.  2    is an exploded perspective view of a secondary battery according to the present disclosure. 
         FIG.  3    is a plan view of a pouch case according to the present disclosure. 
         FIG.  4    is a cross-sectional view taken along line A-A′ of  FIG.  3   . 
         FIG.  5    is a cross-sectional view taken along line B-B′ of  FIG.  3   . 
         FIG.  6    is a perspective view of a secondary battery according to the present disclosure. 
         FIG.  7    is a diagram showing a first example in which a secondary battery and a cooling plate are coupled to configure a secondary battery pack according to the present disclosure. 
         FIGS.  8 A and  8 B  are detailed enlarged views of  FIG.  7   . 
         FIG.  9    is a diagram showing a second example in which a secondary battery and a cooling plate are coupled to configure a secondary battery pack according to the present disclosure. 
         FIGS.  10 A and  10 B  are detailed enlarged views of  FIG.  9   . 
         FIG.  11    is a diagram showing a third example in which a secondary battery and a cooling plate are coupled to configure a secondary battery pack according to the present disclosure. 
         FIGS.  12 A and  12 B  are detailed enlarged views of  FIG.  11   . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. The following detailed description is merely exemplary and is intended to explain exemplary embodiments of the present disclosure. 
       FIG.  2    is an exploded perspective view of a secondary battery  300  according to the present disclosure. 
     Referring to  FIG.  2   , the secondary battery  300  according to the present disclosure may include a pouch case  100  and an electrode assembly  200  including a plurality of electrodes that are stacked with a separator interposed therebetween. Here, the pouch case  100  may accommodate and surround the electrode assembly  200  and may be packed via sealing of sealing portions  150  that contact each other. 
     First and second electrode tabs  220  and  230  may be formed at opposite ends of the electrode assembly  200 , and although  FIG.  2    illustrates the case in which electrode tabs are formed on opposite side surfaces of the electrode assembly  200 , the configuration of the electrode tab of the secondary battery  300  according to the present disclosure is not limited thereto, and it may be possible to simultaneously dispose the first and second electrode tabs  220  and  230  on any one of side surfaces of the sealing portions  150 . 
     Referring to  FIG.  2   , the pouch case  100  according to the present disclosure may include first and second accommodation portions  110  and  120  that are formed to accommodate the electrode assembly  200 , the sealing portions  150  that are formed along an outer part of the pouch case  100  to surround the first and second accommodation portions  110  and  120 , and a connecting portion  140  that is formed with the same depth as that of the first and second accommodation portions  110  and  120  and is configured to connect the first and second accommodation portions  110  and  120  at a predetermined interval ‘d’, and protrusions  130  that protrude in a direction toward sealing portions  150  may be formed at opposite ends of the connecting portion  140 . 
     One pair of first and second accommodation portions  110  and  120  for accommodating the electrode assembly  200  may be formed in the pouch case  100 . The first and second accommodation portions  110  and  120  may be formed with a recessed shape in the pouch case  100  using a method of pressing an internal portion of the pouch case  100 , etc. Here, each of the first and second accommodation portions  110  and  120  may have a size corresponding to the width and length of the electrode assembly  200 , and the sum of the lengths of the first and second accommodation portions  110  and  120  may be formed to correspond to a thickness ‘t’ of the electrode assembly  200 . 
     The connecting portion  140  may be a component that is formed with the same depth as that of the first and second accommodation portions  110  and  120  and connects the first and second accommodation portions  110  and  120  to be spaced apart from each other at the predetermined interval ‘d’, and may connect the first and second accommodation portions  110  and  120  as if bottoms surfaces of the first and second accommodation portions  110  and  120  extend. Here, the first accommodation portion may be connected to one side of the connecting portion  140  along a first bent line, and the second accommodation portion may be connected to the other side of the connecting portion  140  along a second bent line. When the secondary battery  300  is configured using the pouch case  100  according to the present disclosure, the pouch case  100  may be bent along the first and second bent lines  101  and  102  and may accommodate the electrode assembly  200 . 
     Accordingly, the connecting portion  140  may configure a side surface portion  310  of the secondary battery  300  after the secondary battery  300  is assembled, and thus, the width of the connecting portion  140  may be determined to space the first and second bent lines  101  and  102  apart from each other at the predetermined interval ‘d’ by as much as a distance corresponding to the thickness ‘t’ of the electrode assembly  200 . The width of the connecting portion  140  may be the same as the predetermined interval ‘d at which the first and second bent lines  101  and  102  are spaced apart from each other, and as described above, the predetermined interval ‘d’ may be set to be substantially the same as the thickness ‘t’ of the electrode assembly  200 , but the width of the connecting portion  140  is not limited thereto, and as necessary, the width of the connecting portion  140  may be smaller or larger than the thickness of the electrode assembly  200 . 
     The protrusions  130  that protrude in a direction toward the sealing portions  150  may be formed at opposite ends of the connecting portion  140 . 
     The protrusions  130  may be a component for easily folding the sealing portions  150  without distortion of opposite ends of the side surface portion  310  of the secondary battery  300  when the sealing portions  150  are folded to allow the first and second accommodation portions  110  and  120  to face each other in order to form the accommodation space for accommodating the electrode assembly  200  by the pouch case  100 , and may include a top portion  131  formed with a predetermined height on a bottom surface of the connecting portion  140 , and an inclination portion  132  that is formed to be inclined toward the bottom surface of the connecting portion  140  at one end of the top portion  131 . 
     A detailed shape of the protrusions  130  will be understood with reference to  FIGS.  3  to  5   . 
       FIG.  3    is a plan view of the pouch case  100  according to the present disclosure.  FIG.  4    is a cross-sectional view taken along line A-A′ of  FIG.  3   .  FIG.  5    is a cross-sectional view taken along line B-B′ of  FIG.  3   . 
     Referring to  FIG.  4   , the protrusions  130  may include the top portion  131  that extends with the same height as that of the sealing portions  150 , and the inclination portion  132  that is formed to be inclined toward the bottom surface of the connecting portion  140  at one end of the top portion  131 . As shown in  FIG.  4   , the inclination portion  132  may be gradually connected to the top portion  131  and the bottom surface of the connecting portion  140  with a predetermined radius of curvature while being connected to the top portion  131  and the bottom surface of the connecting portion  140 . As such, the protrusions  130  may be formed to be gradually connected to the sealing portions  150  and the connecting portion  140  without discontinuous inclination, and thus, when the pouch case  100  is folded, an effect of preventing the protrusions  130  positioned on the side surface portion  310  of the secondary battery  300  from being damaged or torn may be achieved. 
     Referring to  FIG.  5   , the protrusions  130  may be formed on the connecting portion  140  that connects the first and second accommodation portions  110  and  120  to be spaced apart from each other, and the width of the protrusions  130  may be formed to be smaller than the predetermined interval ‘d’ at which the first and second accommodation portions  110  and  120  are spaced apart from each other. 
     Thus far, although the example in which the top portions  131  of the protrusions  130  extend with the same height as that of the sealing portions  150  and the width of the protrusions  130  is formed to be smaller than the predetermined interval ‘d’ has been described, the height of the top portions  131  and the width of the protrusions  130  are not limited thereto, and it may be possible to adjust the height, the width, or the like of the protrusions  130  according to the thickness ‘t’ and the shape of the electrode assembly  200  or a material of the pouch case  100 . 
       FIG.  6    is a perspective view of the secondary battery  300  according to the present disclosure. 
     The secondary battery  300  using the pouch case  100  according to the present disclosure may include the pouch case  100  according to the present disclosure and the electrode assembly  200 , and the pouch case  100  may be sealed along the sealing portions  150  after the electrode assembly  200  is accommodated in the accommodation space formed by folding the sealing portions  150  to allow the first and second accommodation portions  110  and  120  to face each other. 
     Referring to  FIG.  6   , the connecting portion  140  of the pouch case  100  may be configured to uniformly form the side surface portion  310  of the secondary battery  300 , and dimples  320  that are recessed toward an internal part of the secondary battery  300  at a position corresponding to the protrusions  130  may be formed at opposite ends of the side surface portion  310  of the secondary battery  300 . 
     The dimples  320  may guide the sealing portions  150  at opposite ends of the side surface portion  310  to be easily folded when the pouch case  100  is folded, and may have various sizes and shapes according to the height, the weight, or the like of the protrusions  130 , which is appropriately adjusted according to the thickness ‘t’ and the shape of the electrode assembly  200  or a material of the pouch case  100 . 
     As shown in  FIG.  6   , the secondary battery  300  using the pouch case  100  according to the present disclosure may be configured in such a way that the side surface portion  310  is not entirely concavely recessed or does not protrude, but instead, is formed with a flat and uniform shape. 
     Accordingly, the secondary battery  300  according to the present disclosure may have high heat dissipation efficiency due to low heat resistance because the side surface portion  310  is fully close to a cooling plate  500  when the side surface portion  310  contacts the cooling plate  500  to cool the secondary battery  300 . 
     The secondary battery  300  using the pouch case  100  according to the present disclosure may be configured in such a way that the side surface portion  310  is not entirely concavely recessed or does not protrude, but instead, is formed with a flat shape, and thus, the secondary battery  300  according to the present disclosure may have high heat dissipation efficiency due to low heat resistance because the side surface portion  310  is fully close to the cooling plate  500  when the side surface portion  310  contacts the cooling plate  500  to cool the secondary battery  300 . 
     In addition, the secondary battery  300  according to the present disclosure may be configured in such a way that the side surface portion  310  is uniformly formed rather than to protrude, and thus, the side surface portion  310  may occupy a smaller space with respect to the same battery capacitance than the case in which the side surface portion  310  is folded outward or protrudes due to a separate sealing member, and accordingly, the secondary battery  300  according to the present disclosure may advantageously have high energy density. 
     The sealing portions  150  that are positioned at portions adjacent to opposite end portions of the side surface portion  310  of the secondary battery  300  may include an extension portion  151  that protrudes by a predetermined length in a perpendicular direction to the side surface portion  310  of the secondary battery  300  during a procedure of folding the sealing portions  150  for packaging. Accordingly, a space may be formed between the extension portion  151  and the side surface portion  310  by as much as a length in which the extension portion  151  extends. Here, the length of the extension portion  151  may be several mm. 
     The extension portion  151  formed as described above may perform a function of maintaining or fixing arrangement of the secondary battery  300  with respect to the cooling plate  500  by forming a groove  520  or a step difference  510  for accommodating the extension portion  151  on a side surface of the cooling plate  500  when the secondary battery  300  according to the present disclosure and the cooling plate  500  are coupled to manufacture a secondary battery pack. 
       FIGS.  7  to  12    are diagrams showing first to third examples in which the secondary battery  300  and the cooling plate  500  are coupled to manufacture a secondary battery pack according to the present disclosure. 
       FIGS.  7 ,  8 A, and  8 B  are diagrams showing the first example of the secondary battery pack according to the present disclosure, and a detailed enlarged view thereof. 
     Referring to  FIG.  7   , the secondary battery  300  according to the present disclosure may be disposed in a plural number on the cooling plate  500  and may configure the secondary battery pack. Here, the cooling plate  500  may include a first side surface, a second side surface facing the first side surface, and one or more upper surfaces, which surface-contact the side surface portion  310  of the secondary battery  300 . 
     In the first example of the secondary battery pack shown in  FIG.  7   , a width between the first and second side surfaces of the cooling plate  500  may correspond to the length of the connecting portion  140  of the secondary battery  300 . Referring to  FIGS.  8 A and  8 B , in this case, the cooling plate  500  may be configured to be inserted between the extension portions  151  of the secondary battery  300  when the upper surface of the cooling plate  500  is held close to the side surface portion  310  of the secondary battery  300 . 
     Due to this structure, movement of the secondary battery  300  in a length direction of the secondary battery  300  may be limited, and thus, a position of the secondary battery  300  may be prevented from being separated from the cooling plate  500  and an effect of maintaining arrangement between the secondary battery  300  and the cooling plate  500  may be achieved. 
       FIGS.  9  and  10    are a diagram showing the second example of the secondary battery pack according to the present disclosure, and a detailed enlarged view thereof, respectively. 
     According to the second example of the secondary battery pack shown in  FIG.  9   , a width between the first and second side surfaces of the cooling plate  500  may be formed to be larger than the length of the connecting portion  140  of the secondary battery  300 , and the step difference  510  may be formed with a height equal to or larger than a predetermined length by which the extension portion  151  of the secondary battery  300  protrudes on each of the first and second side surfaces of the cooling plate  500 . Referring to  FIGS.  10 A and  10 B , the extension portion  151  of the secondary battery  300  may be formed to be put on the step difference formed on the cooling plate  500  when the upper surface of the cooling plate  500  is held close to the side surface portion  310  of the secondary battery  300 . 
     Due to this structure, movement of the secondary battery  300  in a length direction of the secondary battery  300  may be limited, and thus, a position of the secondary battery  300  may be prevented from being separated from the cooling plate  500  and an effect of maintaining arrangement between the secondary battery  300  and the cooling plate  500  may be achieved. In addition, in the secondary battery pack according to the second example, the width of the cooling plate  500  may further extend compared with that of the cooling plate  500  according to the first example, and thus, an effect of further enhancing cooling efficiency may be achieved. 
       FIGS.  11  and  12    are a diagram showing the third example of the secondary battery pack according to the present disclosure, and a detailed enlarged view thereof, respectively. 
     According to the third example of the secondary battery pack shown in  FIG.  11   , a width between the first and second side surfaces of the cooling plate  500  may be formed to be larger than the length of the connecting portion  140  of the secondary battery  300 , and one or more grooves  520  may be formed with a depth equal to or larger than a predetermined length of the extension portion  151  on each of the first and second side surfaces of the cooling plate  500 , in order to accommodate the extension portion  151  of the secondary battery  300 . Referring to  FIGS.  12 A and  12 B , the extension portion  151  of the secondary battery  300  may be formed to be accommodated in the groove  520  formed on the cooling plate  500  when the upper surface of the cooling plate  500  is held close to the side surface portion  310  of the secondary battery  300 . 
     Due to this structure, movement of the secondary battery  300  both in a length direction of the secondary battery  300  and a perpendicular direction thereto may be limited, and thus, a position of the secondary battery  300  may be prevented from being separated from the cooling plate  500  and an effect of maintaining arrangement between the secondary battery  300  and the cooling plate  500  may be achieved. In addition, in the secondary battery pack according to the third example, the width of the cooling plate  500  may further extend compared with that of the cooling plate  500  according to the first example, and thus, an effect of further enhancing cooling efficiency may be achieved. 
     Overall, referring to  FIGS.  7  to  12   , in the secondary battery pack according to the present disclosure, each of the plurality of secondary batteries  300  disposed on the cooling plate  500  may be disposed to hold the side surface portion  310  to be close to the cooling plate  500  to dissipate heat of the secondary battery  300 , and movement of the secondary battery  300  may be limited in a length direction of the secondary battery  300  with respect to the cooling plate  500 , and thus, due to the extension portion  151  that protrudes by a predetermined length with respect to the side surface portion  310  of the secondary battery  300 , a position of the secondary battery  300  may be prevented from being separated from the cooling plate  500  and an effect of maintaining arrangement between the secondary battery  300  and the cooling plate  500  may be achieved. 
     According to the present disclosure, in the pouch case, and the secondary battery and the secondary battery pack using the same, a perfect cooling structure may be acquired by uniformly forming one side surface of a secondary battery, and thus, an effect of holding one side surface of the secondary battery to be close to a cooling plate to maximize cooling efficiency may be achieved. 
     According to the present disclosure, in the pouch case, and the secondary battery and the secondary battery pack using the same, a side surface portion of the secondary battery may be formed to be flat rather than to protrude, and thus, a relatively small space may be occupied with respect to the same battery capacitance, thereby achieving an effect of having high energy density. 
     Thus far, the present disclosure has been described based on exemplary embodiments for exemplifying the principle of the present disclosure, the present disclosure is not limited to the configuration and operation shown in the drawings and described in the specification. Those skilled in the art will appreciate that the present disclosure may be carried out in other specific ways than those set forth herein without departing from the spirit and essential characteristics of the present disclosure. Accordingly, the above-mentioned exemplary embodiments are exemplary in any aspect and are not limited. The scope of the present disclosure is determined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and the equivalents thereof should be interpreted to be within the scope of the present disclosure.