Patent Publication Number: US-10312478-B2

Title: Battery pack

Description:
INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 10-2014-0045356, filed on Apr. 16, 2014, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
     This application relates to U.S. patent application Ser. No. 14/605,172 entitled “Battery Pack”, which is concurrently filed as this application and incorporated herein by reference in their entirety. 
     BACKGROUND 
     Field 
     The described technology generally relates to battery packs. 
     Description of the Related Technology 
     Due to the development of wireless Internet or communication technologies, use of portable electronic appliances that operate using a battery, instead of being used at fixed locations, has become common. Thus, the markets for various electronic appliances such as mobile phones, game consoles, portable multimedia players (PMP), MPEG audio layer-3 (MP3) players, smartphones, smart pads, electronic book terminals, flexible tablet computers, and wearable medical equipment have grown remarkably. 
     Among these devices, mobile computers are compact and easy to carry, and thus, are widely used for work or personal purposes at fixed locations or when traveling. To this end, mobile computers generally include a battery pack as a power supply device. A typical battery pack includes a plurality of unit batteries that can be repeatedly charged and discharged in order to provide a sufficient power output. 
     As the market for mobile electronic appliances has expanded, various types of mobile electronic appliances are provided according to users&#39; needs. Thus, requirements for battery packs suitable for the many types of mobile electronic appliances have also increased. In particular, as users have become interested in curved mobile electronic appliances, requests for curved battery packs have increased. 
     SUMMARY OF CERTAIN INVENTIVE ASPECTS 
     One inventive aspect is a battery pack structure. 
     Another aspect is a battery pack which includes: a case having an opening at one end, a first main wall that is concave, and a second main wall that is convex and faces the first main wall; an electrode assembly accommodated in the case; and an uneven portion formed on the second main wall. 
     The first main wall and the second main wall may be curved to respectively have a predetermined radius of curvature. 
     The uneven portion may be formed in a center portion of the second main wall. 
     A plurality of uneven portions may be formed on the second main wall. 
     The plurality of uneven portions may be symmetrically formed with respect to the center portion of the second main wall. 
     The uneven portion may inwardly protrude from the outside to the inside of the second main wall. 
     The uneven portion may be formed in a lengthwise direction of the case. 
     The thickness of a center portion of the second main wall may be smaller than a thickness of a center portion of the first main wall. 
     The uneven portion formed in the second main wall may extend in a width direction of the case. 
     The uneven portion may protrude into the case. 
     The predetermined radius of curvature of the second main wall may be greater than the predetermined radius of curvature of the first main wall. 
     The predetermined radius of curvature of the second main wall may be about 200 mm or greater. 
     The difference between the predetermined radius of curvature of the first main wall and the predetermined radius of curvature of the second main wall may be from about 10 mm to about 30 mm. 
     The electrode assembly may be curved along the first main wall and the second main wall. 
     The battery pack may further include: a cap plate that seals the opening of the case; and an electrode pin that is disposed on an upper surface of the cap plate and is electrically connected to the electrode assembly. 
     The electrode pin may have a first polarity, and the cap plate may have a second polarity that is different from the first polarity. 
     The cap plate may include a first side corresponding to the first main wall and a second side corresponding to the second main wall, wherein the first side of the cap plate has same radius of curvature as the first main wall, and the second side of the cap plate has same radius of curvature as the second main wall. 
     Another aspect is a battery pack which includes: a case having an opening at one end, a first main wall that is concave, and a second main wall that is convex and faces the first main wall, wherein the first main wall and the second main wall are curved to have respectively have a predetermined curvature; an electrode assembly accommodated in the case; a cap plate that seals the opening of the case; and an uneven portion that is formed in a center portion of the second main wall in a lengthwise direction of the case. 
     The uneven portion formed in the second main wall may extend in a width direction of the case. The uneven portion may protrude into the case. 
     Another aspect is a battery pack comprising: an electrode assembly; a case accommodating the electrode assembly, wherein the case includes first and second walls opposing each other and respectively concavely and convexly shaped with respect to the electrode assembly; and an uneven portion formed on the second wall. 
     In the above battery pack, each of the first and second walls has a predetermined radius of curvature. In the above battery pack, the uneven portion is formed in a substantially center portion of the second wall. In the above battery pack, the uneven portion comprises at least one protrusion and at least one recess alternately formed with respect to each other. In the above battery pack, the uneven portions are substantially symmetrical with respect to the center portion of the second wall. In the above battery pack, at least part of the uneven portion extends toward the electrode assembly. In the above battery pack, the uneven portion is formed in a lengthwise direction of the case. In the above battery pack, the thickness of a center portion of the second wall is less than the thickness of a center portion of the first wall. 
     In the above battery pack, the uneven portion extends in a width direction of the case. In the above battery pack, the predetermined radius of curvature of the second wall is greater than the predetermined radius of curvature of the first wall. In the above battery pack, the predetermined radius of curvature of the second wall is about 200 mm or greater. In the above battery pack, the difference between the predetermined radius of curvature of the first wall and the predetermined radius of curvature of the second wall is in the range from about 10 mm to about 30 mm. In the above battery pack, the electrode assembly is curved along the first and second walls. 
     The above battery pack further comprises: a cap plate substantially sealing the electrode assembly inside the case; and an electrode pin located on an upper surface of the cap plate and electrically connected to the electrode assembly. In the above battery pack, the electrode pin has a first polarity, and wherein the cap plate has a second polarity that is different from the first polarity. In the above battery pack, the cap plate comprises a first side corresponding to the first wall and a second side corresponding to the second wall, wherein the first side of the cap plate has substantially the same radius of curvature as the first wall, and wherein the second side of the cap plate has substantially the same radius of curvature as the second wall. 
     Another aspect is a battery pack comprising: an electrode assembly; a case accommodating the electrode assembly, wherein the case includes first and second walls opposing each other, wherein the first wall is curved toward the electrode assembly, wherein the second wall is curved away from the electrode assembly, and wherein the case has a length and a width less than the length; a cap plate substantially sealing the electrode assembly inside the case; and an uneven portion formed in a substantially center portion of the second wall along the direction of the length of the case. In the above battery pack, the uneven portion extends in the direction of the width of the case. In the above battery pack, at least part of the uneven portion extends toward the electrode assembly. 
     Another aspect is a battery pack comprising: an electrode assembly; and a case accommodating the electrode assembly, wherein the case includes first and second walls opposing each other, wherein the first wall is curved toward the electrode assembly, wherein the second wall is curved away from the electrode assembly, wherein the case has a length and a width less than the length, and wherein the second wall includes an uneven portion formed along the direction of the length of the case. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic exploded perspective view of a battery pack according to an embodiment. 
         FIG. 2  is an exploded perspective view illustrating a battery pack formed by deforming the battery pack of  FIG. 1  by applying a pressure thereto. 
         FIG. 3  is a cross-sectional view of the battery pack of  FIG. 1  cut along a line III-III. 
         FIG. 4  is a cross-sectional view of the battery pack of  FIG. 2  cut along a line IV-IV. 
     
    
    
     DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS 
     Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to explain aspects of the present description. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. 
     As the inventive concept allows for various changes and many different forms, particular embodiments will be illustrated in the drawings and described in detail in the written description. 
     Embodiments will be described below in more detail with reference to the accompanying drawings. Those components that are the same or are in correspondence are rendered the same reference numeral regardless of the figure number, and redundant explanations are omitted. 
     It will be understood that although the terms “first”, “second”, etc. may be used herein to describe various components, these components should not be limited by these terms. These components are only used to distinguish one component from another. 
     Singular expressions, unless defined otherwise in contexts, include plural expressions. 
     In the embodiments below, it will be further understood that the terms “comprise” and/or “have” used herein specify the presence of stated features or components, but do not preclude the presence or addition of one or more other features or components. 
     It will also be understood that when an element such as a layer, an area, or a component is referred to as being “on” or “on the top of” another element, it can be directly on or directly on the top of the other element, or intervening layers, areas, or components may also be present. In this disclosure, the term “substantially” includes the meanings of completely, almost completely or to any significant degree under some applications and in accordance with those skilled in the art. Moreover, “formed on” can also mean “formed over.” 
     In the embodiments below, an x-axis, a y-axis, and a z-axis are not limited to three axes on a rectangular coordinates system but may be construed as including these axes. For example, an x-axis, a y-axis, and a z-axis may be at right angles or may also indicate different directions from one another, which are not at right angles. 
     Also, in the drawings, for convenience of description, sizes of elements may be exaggerated or contracted. In other words, since sizes and thicknesses of components in the drawings are arbitrarily illustrated for convenience of description, the following embodiments are not limited thereto. 
     Referring to  FIG. 1 , the battery pack  100  includes a case  110 , an electrode assembly  130 , a cap plate  150 , and an uneven portion  114 . The battery pack  100  may be a rechargeable secondary battery such as a lithium-ion battery. 
     The case  110  has an opening at one end, and may be partitioned into a first main wall or a first wall  111 , a second main wall or a second wall  113  facing the first main wall  111 , a first connection wall  115  connecting a first end of the first main wall  111  and a first end of the second main wall  113 , and a second connection wall  116  connecting a second end of the first main wall  111  and a second end of the second main wall  113  (see  FIG. 3 ). The case  110  has an opening and inner space that are surrounded by the first main wall  111 , the second main wall  113 , the first connection wall  115 , and the second connection wall  116 . The electrode assembly  130  may be inserted through the opening to be accommodated in the inner space of the case  110 . 
     The case  110  may have a substantially hexahedral shape with an opening in an upper portion thereof, and may be formed of a metallic material to provide rigidity to the case  110 . For example, the case  110  may be formed of aluminum or an aluminum alloy. After the electrode assembly  130  is inserted into the case  110  through the opening, the opening may be encapsulated by using the cap plate  150 . The cap plate  150  may also be formed of aluminum or a metallic material such as an aluminum alloy, like the case  110 . The cap plate  150  and the case  110  may be bonded by laser welding to thereby tightly seal the battery pack  100 . 
     The uneven portion  114  may be formed in the second main wall  113  of the case  110 . As will be described in detail later, the uneven portion  114  can be formed in the second main wall  113 , which has a convex shape, as the first main wall  111  and the second main wall  113  of the case  110  having predetermined curvatures are formed. Although not shown on the drawings, the uneven portion  112  can be formed on both the first and second main walls  111  and  113 . 
     In some embodiments, a plurality of uneven portion  114  may be formed in a center portion of the second main wall  113 , and in this case, the uneven portion  114  may be substantially symmetrically formed with respect to the center portion of the second main wall  113 . The uneven portion  114  may be formed in a lengthwise direction of the case  110  (Z-axis). While a plurality of uneven portions  114  are formed in the second main wall  113  in  FIG. 1 , the disclosed embodiments are not limited thereto. According to sizes of the battery packs  100  and  200  and a degree of curvature thereof, one uneven portion  114  may be formed or a plurality of uneven portions  114  may be formed. 
     The uneven portion  114  may include a convex portion  114   a , a concave portion  114   b , and a connection portion  114   c  that are continuously formed. The convex portion  114   a  and the concave portion  114   b  may be alternately connected to each other, and the convex portion  114   a  and the concave portion  114   b  may be connected via the connection portion  114   c.    
     In some embodiments, the uneven portion  114  includes an uneven structure that is formed by applying a pressure to the second main wall  113 . Accordingly, the form of the uneven portion  114  may vary according to a shape of a pressing unit (not shown) of a pressing instrument (not shown). For example, the uneven portion  114  may be curved, round, or polygonal. However, for convenience of description, description below will focus on an uneven structure having a continuous and rectangular shape. 
     The uneven portion  114  may be formed such that the convex portion  114   a  is directed outwardly by applying a pressure to the second main wall  113  from the inside to the outside. That is, when a pressure is applied to the second main wall  113 , the connection portion  114   c  may extend so that the convex portion  114   a  is directed to the outside of the case  110 . Also, similar to a method of applying a pressure to the second main wall  113  but modifying a direction of applying the pressure, when a pressure is applied to the second main wall  113  from the outside to the inside, the connection portion  114   c  may extend so that the concave portion  114   b  is directed to the inside of the case  110 . 
     The electrode assembly  130  may include a first electrode layer  131 , a second electrode layer  132 , and a separator  133  between the first electrode layer  131  and the second electrode layer  132 . The electrode assembly  130  may have a structure in which a plurality of first electrode layers  131 , second electrode layers  132 , and separators  133  are stacked. For example, the electrode assembly  130  may have a jelly-roll structure in which the first electrode layers  131 , the second electrode layers  132 , and the separators  133  are wound around one another. However, for convenience of description, the description will focus on the electrode assembly  130  having a jelly-roll structure in which the first electrode layers  131 , the second electrode layers  132 , and the separators  133  are wound around one another. 
     The first electrode layer  131  may be one of a positive electrode film and a negative electrode film. For example, when the first electrode layer  131  is a positive electrode film, the second electrode layer  132  is a negative electrode film. As another example, when the first electrode layer  131  is a negative electrode film, the second electrode layer  132  is a positive electrode film. That is, the first electrode layer  131  and the second electrode layer  132  have different electrical polarities and are not limited to a predetermined polarity. However, for convenience of description, the first electrode layer  131  formed of a positive electrode film and the second electrode layer  132  formed of a negative electrode film will be described. 
     The first electrode layer  131  may include a first metal collector (not shown) and a first active material portion (not shown) formed by coating a surface of the first metal collector with a first active material (not shown). Likewise, the second electrode layer  132  may include a second metal collector (not shown) and a second active material portion (not shown) formed by coating a surface of the second metal collector with a second active material (not shown). 
     As the first electrode layer  131  is a positive electrode film, the first metal collector may be a positive electrode collector, and the first active material portion may be a positive active material portion. Also, as the second electrode layer  132  is a negative electrode film, the second metal collector may be a negative electrode collector, and the second active material portion may be a negative active material portion. The material and structure of the positive electrode collector, the positive electrode active material portion, the negative electrode collector, and the negative electrode active material portion may be well-known materials and structures for secondary batteries in the art, and thus, detailed descriptions of the material and structure will be omitted. 
     The separator  133  may be a porous polymer layer such as polyethylene film or a polypropylene film, may be in the form of a woven or nonwoven fiber including polymer fibers, may include ceramic particles, and may be formed of a polymer solid electrolyte. For example, the separator  133  may be formed of polyethylene or polypropylene. The separator  133  may be formed of an independent film or may be formed by forming a nonconductive porous layer on the first electrode layer  131  or the second electrode layer  132 . 
     The separator  133  is formed in order to electrically separate the first electrode layer  131  and the second electrode layer  132  from each other, and the form of the separator  133  may not be the same as the form of the first electrode layer  131  or the second electrode layer  132 . 
     A first electrode plate  134  and a second electrode plate  135  having different polarities may be included. The first and second electrode plates  134  and  135  are installed to electrically connect the electrode assembly  130  to an external device. The first electrode plate  134  is electrically connected to the first electrode layer  131  to have a positive polarity, and the second electrode plate  135  is electrically connected to the second electrode layer  132  to have a negative polarity. 
     The cap plate  150  substantially hermetically seals the opening of the case  110  to protect the electrode assembly  130  installed in the case  110 . The cap plate  150  may have the same form as the opening of the case  110 . Accordingly, the cap plate  150  may include a first side  155  corresponding to the first main wall  111  and a second side  156  corresponding to the second main wall  113 . That is, the cap plate  150  may include the first side  155  that is coupled to the first main wall  111  and the second side  156  that is coupled to the second main wall  113 . 
     An electrode pin  152  may be disposed on the cap plate  150 . The first electrode plate  134  may be electrically connected to the cap plate  150 , and the second electrode plate  135  may be electrically connected to the electron pin  152 . The first electrode plate  134  and the second electrode plate  135  have different polarities, and thus, the cap plate  150  and the electrode pin  152  respectively connected to the first electrode plate  134  and the  135  also have different polarities. For example, the cap plate  150  may have a positive polarity, and the electrode pin  152  may have a negative polarity. Here, in order to prevent a short circuit between the electrode pin  152  and the cap plate  150 , a gasket  151  may be included between the electrode pin  152  and the cap plate  150 . The gasket  151  can be formed of an insulating material and prevent an electrical short circuit between the electrode pin  152  and the cap plate  150 . 
     An electrolyte solution inlet  154  through which an electrolyte solution is injected into the case  110  that is hermetically sealed may be formed in the cap plate  150 . The electrolyte solution inlet  154  may be sealed by using a sealing stopper (not shown) after injecting the electrolyte solution. 
     Also, an insulation case (not shown), a terminal plate (not shown), and an insulation plate (not shown) may be included between the cap plate  150  and the electrode assembly  130 . The insulation case is mounted inside the opening of the case  110  that accommodates the electrode assembly  130 . The terminal plate (not shown) is mounted on a surface of the insulation case and is formed of a conductive material to form an electrical path between the electrode pin  152  and the second electrode plate  135 . The insulation plate (not shown) prevents an electrical short circuit between the terminal plate and the cap plate  150  by insulating an external surface of the terminal plate. 
     The cap plate  150  may include an anchor portion  153  to fix the insulation plate and the terminal plate. The anchor portion  153  may fix the insulation plate and the terminal plate to thereby prevent an electrical short circuit. 
     Referring to  FIG. 2 , the battery pack  200  includes a case  210 , an electrode assembly  230 , a cap plate  250 , and an uneven portion  214 . However, as the battery pack  200  is a modification example obtained by be curving the battery pack  100  of  FIG. 1  by applying a pressure thereto, an external appearance of the battery pack  200  is modified as a shape of the uneven portion  114  is modified as a pressure is applied to the case  110 , and the other portions of the battery pack  200  are the same as those of the battery pack  100  of  FIG. 1 . Accordingly, descriptions not provided in the current embodiment are the same as in the previous embodiment, and the description will focus on the uneven portion  214  and the cap plate  250  which have different external appearances from the previous embodiment. 
     The battery pack  200  has a predetermined curvature as the first main wall  211  and the second main wall  213  are curved due to expansion and contraction of the uneven portion  214 . The battery pack  100  of  FIG. 3 , which is before deformation, and the battery pack  200  of  FIG. 4 , which is after deformation, will be compared below. 
     Referring to the battery pack  100  of  FIG. 3  before deformation, unlike the second main wall  113 , the first main wall  111  may have a planar surface that does not have an uneven structure. On the other hand, the uneven portion  114  may be formed in the center portion of the second main wall  113 . 
     In detail, in the battery pack  100  before deformation, the convex portion  114   a , the concave portion  114   b , and the connection portion  114   c  are formed by applying a pressure to the uneven portion  114 , and the connection portion  114   c  connects the convex portion  114   a  and the concave portion  114   b  at a predetermined inclination. Also, thicknesses of the convex portion  114   a , the concave portion  114   b , and the connection portion  114   c  are respectively reduced compared to a thickness of the second main wall  113  which is not pressed. In particular, when a pressure is applied to the second main wall  113  from the inside to the outside so that the convex portion  114   a  is directed to the outside, the thickness of the convex portion  114   a  may be further reduced. 
     Meanwhile, referring to the deformed battery pack  200  of  FIG. 4 , the first main wall  211  and the second main wall  213  may be curved to have a predetermined curvature. As illustrated in  FIG. 4 , the first main wall  211  may be concavely curved, and the second main wall  213  may be convexly curved. 
     The first main wall  211  that is concavely formed is disposed in an inner portion of the battery pack  200  that is curved, and thus, a center portion of the first main wall  211  of the battery pack  200  after deformation may be thicker than a center portion of the first main wall  111  of the battery pack  100  before deformation. 
     On the other hand, the second main wall  213  that is convexly formed is disposed in an outer portion of the battery pack  200  that is curved, and thus, the center portion of the first main wall  211  of the battery pack  200  after deformation may be thinner than the center portion of the first main wall  111  of the battery pack  100  before deformation. 
     In this case, the uneven portion  214  formed in the second main wall  211  may extend in a width direction of the case  210 . In detail, the connection portion  214   c  receives a horizontal tensile force so as to connect the concave portion  214   b  and the convex portion  214   a  in a substantially flat manner. The length of an arc of the second main wall  213  may be increased by the thickness of the uneven portion  214  that is reduced during molding. As the length of the arc of the second main wall  213  is increased, the convex portion  114   a  that is exposed to the outside of the second main wall  113  before deformation is now substantially flat as illustrated in  FIG. 4  showing a state after deformation, and the thickness of the convex portion  114   a  may be reduced by an extension degree thereof. Accordingly, the uneven portion  214  formed in the second main wall  213  may protrude only into the case  210  into which the electrode assembly  230  is inserted. 
     Accordingly, the length of the first main wall  211  that is concavely formed is reduced by the thickness of the center portion of the first main wall  211  that has increased, and a length of the second main wall  213  is increased by the thickness of the uneven portion  214  formed in the second main wall  213  that is reduced. Thus, the radius of curvature of the second main wall  213  may be greater than the radius of curvature of the first main wall  211 . 
     The radii of curvature of the first main wall  211  and the second main wall  213  are not limited to predetermined curvature values and may be determined according to a user&#39;s requirement. For example, a radius of curvature of the second main wall  213  may be about 200 mm or greater so as to provide convenience to a user who uses an electric device (not shown) including the battery pack  200 . Also, the difference between the radius of curvature of the first main wall  211  and the radius of curvature of the second main wall  213  may be in the range from about 10 mm to about 30 mm so as to provide a slim battery pack  200 . However, depending on the embodiment, the radius of curvature of the second main wall  213  and the radius difference can potentially be outside the above ranges. 
     When a predetermined curvature is formed in the first main wall  211  and the second main wall  213  of the case  210 , the electrode assembly  230  installed in inner space of the case  210  is curved along the first main wall  211  and the second main wall  213 . After installing the electrode assembly  230 , the electrode assembly  230  may be substantially simultaneously curved with the case  210 , or the electrode assembly  230  and the case  210  may be individually curved. 
     When the case  210  is curved, the cap plate  250  that tightly seals the opening of the case  210  may also be curved along the first main wall  211  and the second main wall  213 . The first side  255  of the cap plate  250  connected to the first main wall  211  is formed to have substantially the same curvature as the first main wall  211  such that the first side  255  is connected to the first main wall  211 , and the second side  256  of the cap plate  250  is formed to have the same curvature as the second main wall  213  such that the second side  256  is connected to the second main wall  213 . 
     After the cap plate  250  is installed at the opening of the case  210 , the cap plate  250  may be substantially simultaneously curved, that is, substantially at the same time, with the case  210  after it is installed at the opening of the case  210 . That is, after installing the electrode assembly  230  in the inner space of the case  210 , the cap plate  250  and the case  210  may be tightly sealed by welding. Then, by applying a pressure to the first main wall  211  and the second main wall  213 , a curvature may be substantially simultaneously formed in each of the electrode assembly  230  and the first side  255  and the second side  256  of the cap plate  250 . 
     Also, after curving the cap plate  250  and the case  210 , the cap plate  250  may be inserted into the opening of the case  210  to tightly seal the opening. 
     In general, a battery pack is formed of a rigid material. Thus, after manufacturing the battery pack, when the battery pack is pressed to form a predetermined curvature therein, cracks may be generated in the battery pack due to limited elongation of the material thereof. In addition, a predetermined curved form of the battery pack may not be maintained when a pressure is applied thereto and a portion of the battery pack may expand in a thickness direction. 
     According to at least one of the disclosed embodiments, when manufacturing the curved battery packs  100  and  200  by forming the uneven portions  114  and  214 , the length of an arc of the second main walls  113  and  213  may be extended to thereby form a curvature in the battery packs  100  and  200  by applying a relatively small force thereto. Thus, the manufacturing process may be performed with a minimum energy. Also, material deformation such as cracks or destruction of the base  110  may be minimized by increasing a length of the arc of the second main wall  113 . 
     Due to operating conditions of a battery pack such as overcharging, overdischarging, an internal short circuit, and overheating, an internal temperature of the case surrounding the external surface of the battery pack may increase, and an internal gas pressure may excessively increase. In this case, swelling of the case  100  occurs. However, according to at least some embodiments, the uneven portions  114  and  214  formed in the cases  110  and  210  are flexible, and thus, a pressure of gas generated in the battery packs  100  and  200  may be distributed to thereby minimize the swelling. 
     As the battery pack  200  may be deformed when forming a curvature therein according to the form of an electronic device (not shown), spatial utility of the electronic device may be increased. 
     According to at least one of the disclosed embodiments, durability and safety of a battery pack may be improved. 
     It should be understood that the exemplary embodiments described therein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments. 
     While the inventive technology has been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.