Abstract:
Provided are a battery cell for a secondary battery and a battery pack having the same, and more particularly, a battery cell for a secondary battery including a case having an electrode assembly space having the same shape as an electrode assembly, and a battery pack having the same.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2013-0042696, filed on Apr. 18, 2013, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The following disclosure relates to a battery cell for a secondary battery and a battery pack having the same, and more particularly, to a battery cell for a secondary battery including a case having an electrode assembly space having the same shape as an electrode assembly, and a battery pack having the same. 
       BACKGROUND 
       [0003]    Generally, a secondary battery may be rechargeable and have increased capacity. A representative example of the secondary battery includes a nickel cadmium battery, a nickel hydrogen battery, a lithium ion battery, and the like. Among them, the lithium ion battery has been spotlighted as the next generation power source due to excellent characteristics such as a long lifespan, high capacity, and the like. Among them, a lithium secondary battery, which has operating voltage of 3.6 V or more, is used as a power supply of a portable electronic device or several lithium secondary batteries are connected in series with each other to thereby be used for a high output hybrid vehicle. Since this lithium secondary battery has operating voltage three times higher than that of the nickel-cadmium battery or the nickel-metal hydride battery and is more excellent in view of energy density characteristics per unit weight than the nickel-cadmium battery or the nickel-metal hydride battery, the use of the lithium secondary battery has rapidly increased. 
         [0004]    The lithium secondary battery may be manufactured in various types. A representative type of the lithium secondary battery may include a cylindrical type and a prismatic type that are mainly used for the lithium ion battery. A lithium polymer battery that has been recently spotlighted is manufactured in a pouch type having flexibility, such that it has a relatively free shape. In addition, the lithium polymer battery has excellent stability and light weight, such that it is advantageous for slimness and lightness of the portable electronic device. 
         [0005]      FIG. 1  is a view showing a structure of a pouched cell of a secondary battery according to related art and  FIG. 2  is a view showing a longitudinal cross-section of the pouched cell of the secondary battery according to the related art. As shown, the pouched cell  10  includes a battery part  11  and a case  12  including a battery part space  12   b  receiving the battery part  11 . The battery part  11  has a shape in which a plurality of positive electrode plates  11   a , separators  11   b , and negative electrode plates  11   c  are stacked. The positive electrode plate  11   a  of the battery part  11  is electrically connected to a positive electrode tap  13  and the negative electrode plate  11   c  is electrically connected to a negative electrode tap  14 . 
         [0006]    In addition, the case  12  is a pouched type case having an intermediate layer formed of a metal foil, wherein the metal foil has an inner and outer cover layers attached to both surfaces thereof and made of an insulating film. Since the pouched type case has excellent formability, it may be freely bent. The case  12  is provided with the battery part space  12   b  capable of receiving the battery part  11  as described above and a closed surface  12   a  provided to a surface which is heat-sealed along an edge of the battery part space  12   b.    
         [0007]    The pouched cell  10  having the configuration described above adheres the case  12  and the battery part  11  to each other by vacuum adsorption in a state in which the battery part  11  is received in the case  12  (see arrows). However, since each of the positive electrode plate  11   a , the separator  11   b , and the negative electrode plate  11   c  of the battery part  11  has a size different from each other, the case  12  is manufactured while having some spare when forming the battery part space  12   b  of the case  12 . As a result, at the time of the vacuum adsorption of the case  12 , impact is applied to the battery part  11  due to a gap  15  between the case  12  and the battery part  11 , such that the positive electrode plate  11   a  and the negative electrode plate  11   c  may be damaged due to the impact. Particularly, when a portion of the plates is separated by the impact to thereby float in the case  12 , the pouched cell  10  may be damaged and performance may be degraded. 
         [0008]    Therefore, a development of a battery cell for preventing the damage of the battery part  11  by minimizing the impact on the case  12  and the battery part  11  at the time of the vacuum adsorption of the case  12  has been demanded. 
       SUMMARY 
       [0009]    An embodiment of the present invention is directed to providing a battery cell for a secondary cell including a case having a battery part space having the same shape as a battery part to minimize impact on the case and the battery part at the time of vacuum adsorption of an inner portion of the case in a state in which the battery part is received in the case, and a battery pack having the same. 
         [0010]    In one general aspect, a battery cell for a secondary battery includes: a battery part including a plurality of first electrode plates and a plurality of second electrode plates alternately stacked thereon, and a separator inserted between the first electrode plate and the second electrode plate, the plurality of first electrode plates and the plurality of second electrode plates including an uppermost layer electrode plate stacked on an uppermost layer of the first electrode plate or the second electrode plate and a lowest layer electrode plate stacked on a lowest layer of the first electrode plate or the second electrode plate, wherein the first electrode plate is a positive electrode plate and the second electrode plate is a negative electrode plate; and a case receiving the battery part, wherein the separator has an area larger than that of the first electrode plate or the second electrode plate, the case is provided with a battery part space receiving the battery part, and a side surface of the battery part space is provided with a bending part along a bending surface of the battery part which is formed due to a step between the first electrode plate or the second electrode plate and the separator. 
         [0011]    The battery part space may include: a first receiving space receiving the uppermost layer electrode plate and the lowest layer electrode plate; and a second receiving space receiving the battery part except for the uppermost layer electrode plate and the lowest layer electrode plate, and the first receiving space and the second receiving space may be partitioned by the bending part. 
         [0012]    The battery cell may include a case including a first case enclosing one surface of the battery part including the uppermost layer electrode plate and a second case enclosing the other surface of the battery part including the lowest layer electrode plate, and the bending part may include: a first bending part formed on the first case and formed between the uppermost electrode plate and the separator, and a second bending part formed on the second case and formed between the lowest electrode plate and the separator. 
         [0013]    In another general aspect, a battery cell for a secondary battery includes: a battery part including a plurality of first electrode plates and a plurality of second electrode plates alternately stacked thereon, and a separator inserted between the first electrode plate and the second electrode plate, the plurality of first electrode plates and the plurality of second electrode plates including an uppermost layer electrode plate stacked on an uppermost layer of the first electrode plate or the second electrode plate and a lowest layer electrode plate stacked on a lowest layer of the first electrode plate or the second electrode plate, wherein the first electrode plate is a positive electrode plate and the second electrode plate is a negative electrode plate; and a case receiving the battery part, wherein the separator has an area larger than that of the first electrode plate or the second electrode plate, the second electrode plate has an area larger than that of the first electrode plate, the case is provided with a battery part space receiving the battery part, and a side surface of the battery part space is provided with a third bending part along a bending surface of the battery part which is formed due to a step between the first electrode plate or the second electrode plate and the separator and a fourth bending part along a bending surface of the battery part which is formed due to a step between the first electrode plate and the second electrode plate. 
         [0014]    The battery part space may include: a third receiving space receiving the uppermost layer electrode plate and the lowest layer electrode plate; a fourth receiving space receiving the first electrode plate or the second electrode plate neighboring to the uppermost layer electrode plate and the first electrode plate or the second electrode plate neighboring to the lowest layer electrode plate; and a fifth receiving space receiving the battery part except for the uppermost layer electrode plate, the first electrode plate or the second electrode plate neighboring to the uppermost layer electrode plate, the lowest layer electrode plate, and the first electrode plate or the second electrode plate neighboring to the lowest layer electrode plate, the third receiving space and the fourth receiving space may be partitioned by the third bending part, and the fourth receiving space and the fifth receiving space may be partitioned by the fourth bending part. 
         [0015]    The battery cell may include a case including a third case enclosing one surface of the battery part including the uppermost layer electrode plate and a fourth case enclosing the other surface of the battery part including the lowest layer electrode plate, and the third bending part may include a 3-1-th bending part formed on the third case and formed between the uppermost electrode plate and the first electrode plate or the second electrode plate neighboring to the uppermost layer electrode plate, and a 3-2-th bending part formed on the fourth case and formed between the lowest electrode plate and the first electrode plate or the second electrode plate neighboring to the lowest layer electrode plate, and the fourth bending part may include a 4-1-th bending part formed on the third case and formed between the first electrode plate or the second electrode plate neighboring to the uppermost layer electrode plate and the separator, and a 4-2-th bending part formed on the fourth case and formed between the first electrode plate or the second electrode plate neighboring to the lowest layer electrode plate and the separator. 
         [0016]    A battery pack for a secondary battery includes the battery cell as described above. 
         [0017]    Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a perspective view of a battery cell for a secondary battery according to the related art; 
           [0019]      FIG. 2  is a partial cross-sectional view taken along the line AA′ of  FIG. 1 ; 
           [0020]      FIG. 3  is a perspective view showing a battery cell for a secondary battery according to a first embodiment of the present invention; 
           [0021]      FIG. 4  is a partial cross-sectional view taken along the line BB′ of  FIG. 3 ; 
           [0022]      FIG. 5  is a perspective view showing a battery cell for a secondary battery according to a second embodiment of the present invention; and 
           [0023]      FIG. 6  is a partial cross-sectional view taken along the line CC′ of  FIG. 5 . 
       
    
    
       [0024]      
         [0000]    
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 [Detailed Description of Main Elements] 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 100, 200: battery cell 
                 110, 210: battery part 
               
               
                   
                 111, 211: first electrode plate 
               
               
                   
                 112, 212: separator 
               
               
                   
                 113, 213: second electrode plate 
               
               
                   
                 120, 220: case 
                 121, 221: closed surface 
               
               
                   
                 122, 222: battery part space 
               
               
                   
                 130, 230: positive electrode tap 
               
               
                   
                 140, 240: negative electrode tap 
               
               
                   
                 150: bending part 
                 151: first bending part 
               
               
                   
                 152: second bending part 
                 250: third bending part 
               
               
                   
                 251: 3-1-th bending part 
                 252: 3-2-th bending part 
               
               
                   
                 260: fourth bending part 
                 261: 4-1-th bending part 
               
               
                   
                 262: 4-2-th bending part 
               
               
                   
                   
               
             
          
         
       
     
       DETAILED DESCRIPTION OF EMBODIMENTS 
       [0025]    Hereinafter, a battery cell for a secondary battery according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings. 
       First Embodiment 
       [0026]      FIG. 3  shows a perspective view of a battery cell  100  according to a first embodiment of the present invention and  FIG. 4  shows a longitudinal cross-sectional view of the battery cell  100  according to the first embodiment of the present invention. As shown, the battery cell  100  may be configured to include a battery part  110 , a case  120 , a positive electrode tap  130 , a negative electrode tap  140 , and a bending part  150 . 
         [0027]    The battery part  110  may have a shape in which a plurality of first electrode plates  111 , separators  112 , and second electrode plates  113  are stacked. Specifically, the plurality of first electrode plates  111  and second electrode plates  113  may be alternately stacked and the separator  112  may be disposed between the alternately stacked first electrode plates  111  and second electrode plates  113 . The battery part  110  may include an uppermost layer electrode plate which is stacked on an uppermost layer of the first electrode plate  111  or the second electrode plate  113  and a lowest layer electrode plate which is stacked on a lowest layer of the first electrode plate  111  or the second electrode plate  113 . Although the drawings show the uppermost layer electrode plate and the lowest layer electrode plate as the first electrode plate  111 , the uppermost layer electrode plate and the lowest layer electrode plate may be configured by the second electrode plate  113 . 
         [0028]    The first electrode plate  111  may be the uppermost layer electrode plate and the lowest layer electrode plate. The first electrode plate  111  may be disposed at both ends of the battery part  110 . The first electrode plate  111  may be configured by a positive electrode plate and the second electrode plate  113  may be configured by a negative electrode plate. The separator  112  may have a cross-sectional area larger than that of the first electrode plate  111  and the second electrode plate  113  to prevent a short circuit between the first electrode plate  111  and the second electrode plate  113  and the first electrode plate  111  may have a cross-sectional area smaller than that of the second electrode plate  113 . The positive electrode plate of the battery part  110  may be electrically connected to a positive electrode tap  140  and the negative electrode plate may be electrically connected to a negative electrode tap  140 . 
         [0029]    As described above, since the first electrode plate  111  has the cross-sectional area smaller that that of the separator  112 , the battery part  110  may have a step generated at a boundary between the uppermost layer electrode plate and the separator  112  neighboring thereto. Therefore, the case  120  receiving the battery part  110  according to an embodiment of the present invention may have the following configuration so that the battery part  110  is closely received in the case  120 . 
         [0030]    The case  120  may be formed in a battery part space  122  receiving the battery part  110  and may be provided with a closed surface  121  which is heat-sealed along an edge of the battery part space  122 . In this case, the bending part  150  corresponding to the step of the boundary between the first electrode plate  111  and the separator  112  described above may be formed on the case  120  having the battery part space  122  formed therein. The bending part  150  may be formed along a bent surface of the battery part  110  which is formed due to the step between the first electrode plate  111  and the separator  112 . The battery part space  122  may include a first receiving space receiving the first electrode plate  111  and a second receiving space receiving the remaining battery part except for the first electrode plate  111 , wherein the first receiving space and the second receiving space may be partitioned by the bending part  150 . Hereinafter, a configuration of the bending part  150  will be described in detail. 
         [0031]    The case  120  may include a first case  120   a  enclosing one surface of the battery part  110  and a second case  120   b  enclosing the other surface of the battery part  110 . The first case  120   a  and the second case  120   b  may be formed integrally with each other to be coupled (single forming) by folding it in half or may be formed separately from each other to be coupled (double forming). The first case  120   a  may include a first closed surface  121   a  for coupling with the second case  120   b , a first battery part surface  123   a  enclosing one surface of the battery part  110 , and a first battery part side surface  124   a  enclosing a side surface of the battery part  110 . A first bending part  151  of the bending part  150  formed at the first case  120   a  may be formed on the first battery part side surface  124   a . The first bending part  151  may be formed along a boundary part between the first electrode plate  111  and the separator  112  neighboring to the first electrode plate  111  disposed on the uppermost layer of the battery part  110 . Therefore, when the battery part  110  is received in the case  120  through the first bending part  151 , a spare space, that is, a gap may be minimized. 
         [0032]    The second case  120   b  may include a second closed surface  121   b  for coupling with the first case  120   a , a second battery part surface  123   b  enclosing the other surface of the battery part  110 , and a second battery part side surface  124   b  enclosing a side surface of the battery part  110 . In this case, a second bending part  152  of the bending part  150 , which is formed at the second case  120   b  may be formed on the second battery part side surface  124   b . The second bending part  152  may be formed along a boundary part between the first electrode plate  111  disposed on the lowest layer of the battery part  110  and the separator  112  neighboring to the first electrode plate  111  disposed on the lowest layer of the battery part  110 . Therefore, when the battery part  110  is received in the case  120  through the second bending part  152 , a spare space, that is, a gap may be minimized. 
       Second Embodiment 
       [0033]      FIG. 5  shows a perspective view of a battery cell  200  according to a second embodiment of the present invention and  FIG. 6  shows a longitudinal cross-sectional view of the battery cell  200  according to the second embodiment of the present invention. As shown, the battery cell  200  may be configured to include a battery part  210 , a case  220 , a positive electrode tap  230 , a negative electrode tap  240 , a third bending part  250 , and a fourth bending part  260 . The battery part  210  may include an uppermost layer electrode plate which is stacked on an uppermost layer of the first electrode plate  211  or the second electrode plate  213  and a lowest layer electrode plate which is stacked on a lowest layer of the first electrode plate  211  or the second electrode plate  213 . Although the drawings show the uppermost layer electrode plate and the lowest layer electrode plate as the first electrode plate  211 , the uppermost layer electrode plate and the lowest layer electrode plate may be configured by the second electrode plate  213 . 
         [0034]    The battery cell  200  according to the second embodiment of the present invention has the same configuration as the battery cell  100  according to the first embodiment of the present invention described above except for a configuration of the case  220 . Therefore, the configuration of the case  220  will be described below in detail. 
         [0035]    As shown in  FIG. 6 , considering that the battery cell  200  according to the second embodiment of the present invention has the separator  212  which is folded at the time of vacuum adsorption of an inner portion of the case  220 , the case  220  has been configured as follows. 
         [0036]    As described above, in the case in which the separator  212  is folded by the vacuum absorption, since the first electrode plate  211  has a cross-sectional area smaller than that of the second electrode plate  213 , the battery part  210  has a step generated at a boundary between an uppermost layer electrode plate (the first electrode plate  211  in  FIG. 6 ) stacked on an uppermost layer of the battery part  210  and a second electrode plate  213  neighboring to the uppermost layer electrode plate. In addition, the step may be generated at a boundary between the second electrode plate  213  neighboring to the uppermost layer electrode plate and the separator  212 . Therefore, the case  220  receiving the battery part  210  according to the second embodiment of the present invention may have the following configuration so that the battery part  210  is closely received in the case  220 . 
         [0037]    The case  220  may be formed in a battery part space  222  receiving the battery part  210  and may be provided with a closed surface  222  which is heat-sealed along an edge of the battery part space  222 . In this case, the case  220  having the battery part space  222  formed therein may be provided with the third bending part  250  corresponding the step of the boundary between the uppermost layer electrode plate (the first electrode plate  211  in  FIG. 6 ) and the second electrode plate  213  neighboring to the uppermost layer electrode plate and the fourth bending part  260  corresponding to the step of the boundary between the second electrode plate  213  neighboring to the uppermost layer electrode plate and the separator  212  neighboring to the second electrode plate  213 . The battery part space  222  may include a third receiving space receiving the uppermost layer electrode plate, a fourth receiving space receiving the second electrode plate  213  neighboring to the uppermost layer electrode plate, and a fifth receiving space receiving the remaining battery parts except for the uppermost layer electrode plate and the second electrode plate  213  neighboring to the uppermost layer electrode plate. The third receiving space and the fourth receiving space may be partitioned by the third bending part  250  and the fourth receiving space and the fifth receiving space may be partitioned by the fourth bending part  260 . Hereinafter, a configuration of the third bending part  250  and the fourth bending part  260  will be described in detail. 
         [0038]    The case  220  may include a third case  220   a  enclosing one surface of the battery part  210  and a fourth case  220   b  enclosing the other surface of the battery part  210 . The third case  220   a  and the fourth case  220   b  may be formed integrally with each other to be coupled (single forming) by folding it in half or may be formed separately from each other to be coupled (double forming). The third case  220   a  may include a first closed surface  221   a  for coupling with the fourth case  220   b , a first battery part surface  223   a  enclosing one surface of the battery part  210 , and a first battery part side surface  224   a  enclosing a side surface of the battery part  210 . A 3-1-th bending part  251  of the third bending part  250  formed at the third case  220   a  may be formed on the first battery part side surface  224   a . The 3-1-th bending part  251  may be formed along a boundary part between the uppermost layer electrode plate (the first electrode plate  211  in  FIG. 6 ) of the battery part  210  and the second electrode plate  213  neighboring to the uppermost layer electrode plate. In addition, a 4-1-th bending part  261  of the fourth bending part  260  formed at the third case  220   a  may be formed so as to be space apart from the 3-1-th bending part  251  on the first battery part side surface  224   a  by a predetermined distance in a downward direction. The 4-1-th bending part  261  may be formed along a boundary part between the second electrode plate  213  disposed to neighbor to the uppermost layer electrode plate of the battery part  210  and the separator  212  neighboring to the second electrode plate  213 . Therefore, when the battery part  210  is received in the case  220  through the 3-1-th bending part  251  and the 4-1-th bending part  261 , a spare space, that is, a gap may be minimized. 
         [0039]    The fourth case  220   b  may include a second closed surface  221   b  for coupling with the third case  220   a , a second battery part surface  223   b  enclosing the other surface of the battery part  210 , and a second battery part side surface  224   b  enclosing a side surface of the battery part  210 . In this case, a 3-2-th bending part  252  of the third bending part  250  formed at the fourth case  220   b  may be formed on the second battery part side surface  224   b . The 3-2-th bending part  252  may be formed along a boundary part between a lowest layer electrode plate (the first electrode plate  211  in  FIG. 6 ) of the battery part  210  and the second electrode plate  213  neighboring to the lowest layer electrode plate. In addition, a 4-2-th bending part  262  of the fourth bending part  262  formed at the fourth case  220   b  may be formed so as to be space apart from the 3-2-th bending part  252  on the second battery part side surface  224   b  by a predetermined distance in an upward direction. The 4-2-th bending part  262  may be formed along a boundary part between the second electrode plate  213  disposed to neighbor to the lowest layer electrode plate of the battery part  210  and the separator  212  neighboring to the second electrode plate  213 . Therefore, when the battery part  210  is received in the case  220  through the 3-2-th bending part  252  and the 4-2-th bending part  262 , a spare space, that is, a gap may be minimized. 
         [0040]    A battery pack for a secondary battery according to an embodiment of the present invention having the battery cell  100  according to the first embodiment of the present invention or the battery cell  200  according to the second embodiment of the present invention stacked in plural, may be configured to include a case receiving the battery cell  100  or  200  and a typical terminal and battery management system (BMS) received in the case. 
         [0041]    According to the embodiment of the present invention, in the battery cell for the secondary battery and the battery pack having the same, since the battery case is received in the state in which it is closely adhered to the case to minimize the impact at the time of the vacuum adsorption of the case, the damage to the battery part may be prevented and the degradation in performance of the battery cell may also be prevented. In addition, when the battery cell is manufactured, the size of the battery cell may be precisely designed by precisely controlling the numerical value of the battery part space of the case. 
         [0042]    The present invention should not be construed to being limited to the above-mentioned exemplary embodiment. The present invention may be applied to various fields and may be variously modified by those skilled in the art without departing from the scope of the present invention claimed in the claims. Therefore, it is obvious to those skilled in the art that these alterations and modifications fall in the scope of the present invention.