Abstract:
A battery pack including: a bare cell having first and second electrode terminals; a holder positioned on a first side of the bare cell, comprising first fastening portions; a protective circuit assembly seated in the holder; and a cover to cover the protective circuit assembly and the bare cell, the cover including second fastening portions. In the battery pack, the first and second fastening portions are interlocked inside of the cover.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 2007-101542, filed Oct. 9, 2007, in the Korean Intellectual Property Office, the disclosure of which is hereby incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Aspects of the present invention relate to a battery pack, and more particularly, to a battery pack capable of preventing a defective appearance and label lifting. 
     2. Description of the Related Art 
     Rechargeable secondary batteries are more economical than disposable dry cells. In recent years, low-volume and high-capacity secondary batteries have been developed, which are widely used as power supplies for portable electronic devices, such as cellular phones, camcorders, notebook computers, and the like. Secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries. 
     Lithium secondary batteries are widely used, because of their small size, high capacity, high operating voltage, and high energy density per weight. Lithium secondary batteries may be classified as can-type lithium secondary batteries or pouch-type lithium secondary batteries, depending on the shape of a casing, which accommodates an electrode assembly having a negative electrode plate, a positive electrode plate, and a separator. The can-type lithium secondary batteries may be further classified as cylinder-type lithium secondary batteries or prismatic-type lithium secondary batteries. 
     The casing of the can-type lithium secondary batteries is generally formed of a metal, such as aluminum, and has a cylindrical shape, a prismatic shape, or a pillar shape with rounded edges. The can has an upper opening through which an electrode assembly is inserted and an electrolyte is injected. A cap assembly is used to seal the opening of the can, resulting in a sealed bare cell. 
     The pouch-type lithium secondary batteries have a pouch casing that accommodates an electrode assembly, on a lower surface of the casing. The lower surface is covered with an upper surface of the pouch casing, and sealing portions are formed by bonding edges of the upper and lower surfaces, resulting in a bare cell. 
     The bare cell is electrically connected with a protecting circuit board, which includes a protecting device to prevent overcharges, over-discharges, over-currents, and the like. In general, the electrical connection between the bare cell and the protecting circuit board is made via a lead. Such a secondary battery may be called a core pack. 
     A hard-pack-type battery pack is formed by inserting the core pack into an additional external case. An inner-pack-type battery pack is formed by filling a space between the bare cell and the protective circuit board with a resin, then labeling the core pack with a thin label. The core pack may include a holder, in which the protective circuit board can be seated. 
     In order to protect the protective circuit board from the outside, a case can be used to cover the protective circuit board. The appearance of a battery pack is formed by forming a protrusion that extends from an out surface of the holder and forming a hole in the case that corresponds to the protrusion. The protrusion is then inserted into the hole. As the protrusion extends outside from the holder, a defective appearance and label lifting can occur when attaching a label. 
     SUMMARY OF THE INVENTION 
     Aspects of the present invention provide a battery pack, which includes: a bare cell having first and second electrode terminals; a holder positioned on one side of the bare cell, including protrusions; a protective circuit assembly seated in the holder; and a cover formed to cover the protective circuit assembly and the bare cell, having holes joined to the protrusions. The protrusions and the holes are joined together, inside of the cover. 
     Aspects of the present invention provide a battery pack, which includes: a bare cell having first and second electrode terminals; a holder positioned on one side of the bare cell, having insertion holes; a protective circuit assembly seated in the holder; and a cover to cover the protective circuit assembly and the bare cell, having insertion protrusions joined to the insertion holes. The insertion holes and the insertion protrusions are joined together, inside of the cover. 
     According to aspects of the present invention, the battery pack may further include an insulating member interposed between the bare cell and the holder. 
     According to aspects of the present invention, the insulating member may include a side portion to cover a first side of the bare cell, an upper portion formed to cover a second side of the bare cell, and a lower portion formed to cover a third side of the bare cell. 
     According to aspects of the present invention, the holder may include a seating portion contacting the first side of the bare cell, support portions the extend perpendicularly from edges of the seating portion. A receiving portion is defined by the seating portion and the support portions. 
     According to aspects of the present invention, the cover may include a side cover to cover the first side of the bare cell, an upper cover to cover the second side of the bare cell, and a lower cover to cover the third side of the bare cell. 
     According to an aspect of the present invention, first and second fastening portions are respectively formed at a holder and a cover, and the first and second fastening portions are joined together inside of the cover, thereby preventing a defective appearance and label lifting, when attaching a label. 
     Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is an exploded perspective view of battery pack, according to an exemplary embodiment of the present invention; 
         FIG. 2A  is a perspective view of a holder and a cover of  FIG. 1 , before the holder is joined to the cover; 
         FIG. 2B  is a perspective view of the holder and cover of  FIG. 2A , after the holder is joined to the cover; 
         FIG. 2C  is a cross-sectional view taken along line A-A′ of  FIG. 2B ; 
         FIG. 3  is an exploded perspective view of battery pack according to an embodiment of the present invention; 
         FIG. 4A  is a perspective view of a holder and a cover of  FIG. 3 , before the holder is joined to the cover; 
         FIG. 4B  is a perspective view of the holder and cover of  FIG. 4A , after the holder is joined to the cover; and 
         FIG. 4C  is a cross-sectional view taken along line B-B′ of  FIG. 4B . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The exemplary embodiments are described below, in order to explain the aspects of the present invention, by referring to the figures. As referred to herein, when a first element is said to be disposed “on”, or adjacent to, a second element, the first element can directly contact the second element, or can be separated from the second element by one or more other elements can be located therebetween. In contrast, when an element is referred to as being disposed “directly on” another element, there are no intervening elements present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
       FIG. 1  is an exploded perspective view of a battery pack, according to an exemplary embodiment of the present invention.  FIG. 2A  is a perspective view of a holder and a cover of  FIG. 1 , before the holder is joined to the cover,  FIG. 2B  is a perspective view of the holder and cover in  FIG. 2A , after the holder is joined to the cover, and  FIG. 2C  is a cross-sectional view taken along line A-A′ in  FIG. 2B . 
     Referring to  FIG. 1 , a battery pack  100 , according to an exemplary embodiment of the present invention, includes a bare cell  10 , a holder  30 , a protective circuit assembly  40 , and a cover  50 . The battery pack  100  can further include an insulating member  20  disposed between the bare cell  10  and the holder  30 . The battery pack  100  includes a label  60  to cover the bare cell  10 , the holder  30 , the protective circuit assembly  40 ,and the cover  50 . 
     The bare cell  10  includes a can  11  and a cap assembly joined to an opening of the can  11 . The bare cell  10  is formed by receiving an electrode assembly and an electrolyte inside the can  11 . The electrode assembly is formed by winding, into a jelly-roll shape, two electrode plates and a separator interposed between the two electrodes. The separator prevents a short of the two electrodes. 
     The can  11  may be formed of iron (stainless steel), aluminum, or the like, using a deep drawing method. The can  11  can have a cylindrical shape, a prismatic shape, a column shape with curved corners, or the like. 
     A first electrode terminal (negative electrode terminal)  13  is formed on an upper surface of the bare cell  10 , and a second electrode terminal (positive electrode terminal)  15  is formed on an opposing lower surface of the bare cell  10 . According to some embodiments, the polarities of the electrode terminals  13  and  15  may be reversed. In some cases, the can  11  may be used as an electrode terminal. The can  11  may have an electrode plate formed on one surface thereof, such that the electrode plate serves as an electrode terminal. The polarities of the can  11  and/or the electrode plate may also be positive or negative, according to particular applications. 
     The electrode plate  15  may have a clad metal structure formed of aluminum and nickel layers. The aluminum layer is welded to the lower surface of the bare cell  10 . The welding may be performed by ultrasonic welding, for example. The nickel layer is connected to a second lead terminal  45  of the protective circuit assembly  40 . 
     The insulating member  20  may be positioned between the bare cell  10  and the holder  30 , or between the bare cell  10  and the first or second lead terminals  43  or  45 . The insulating member  20  can be a double coated adhesive tape to insulate and adhere the bare cell  10  and the holder  30 . 
     The insulating member  20  can include a side portion  21  formed to cover a side surface of the bare cell  10 , and upper and lower portions  23  and  25  respectively extending to cover the upper and lower surfaces of the bare cell  10 . The side portion  21  adheres the side surface of the bare cell  10  to the holder  30 . The upper portion  23  may cover the entire upper surface of the bare cell  10 , or may cover only a portion of the upper surface of the bare cell  10 , which extends between the negative electrode terminal  13  and the side surface of the bare cell  10 . 
     The insulating member  20  prevents the first lead terminal  43  from being easily separated from the bare cell  10 . However, when a washer or the like is formed on the upper surface of the bare cell  10 , to insulate the first lead terminal  43  from the can  11 , the upper portion  23  may be omitted. 
     The lower portion  25  may cover a portion of the lower surface of the bare cell  10 , between the second lead terminal  45  and the side surface of the bare cell  10 . The lower portion  25 , in some embodiments, may cover the entire lower surface of the bare cell  10 . However, when the second lead terminal  45  is positioned close to a lower edge portion of the can  11 , the lower portion  25  may be omitted. 
     The holder  30  is positioned on the side surface of the bare cell  10 . The insulating member  20  adheres the bare cell  10  to the holder  30 . The protective circuit assembly  40  can be seated in the holder  30 . The holder  30  may be formed of a plastic material. The holder  30  can include a seating portion  31  that contacts the side surface of the bare cell  10 , and support portions  33  that extend perpendicularly from edges of the seating portion  31 , thereby forming a receiving portion  35  to receive the protective circuit assembly  40 . The holder  30  includes a plurality of first fastening portions  37 . The first fastening portions  37  are joined to second fastening portions  513  of the cover  50 , which will be described later. 
     Referring to  FIGS. 2A through 2C , the first fastening portions  37  extend from the support portions  33 . The first fastening portions  37  have wedge-shaped portions that interlock with the second fastening portions  513 . Since the first fastening portions  37  are joined to the second fastening portions  513 , inside the cover  50 , it is possible to prevent a defective appearance, due to external protrusions. 
     It will be apparent that the shapes and/or positions of the first fastening portions  37  are not limited to those described in this exemplary embodiment. For example, the first fastening portions  37  may protrude from the seating portion  31  (between the support portions  33 ), or may protrude from ends of the seating portion  31 . 
     The protective circuit assembly  40  includes a protective circuit board  41  on which electric elements, such as a positive temperature coefficient (PTC) thermistor, a protective circuit, and external connection terminals are mounted. The protective circuit assembly  40  includes first and second lead terminals  43  and  45 . When the internal temperature of a battery increases beyond a set level, or the voltage of the battery increases beyond a set level, due to an over-charge, or the like, the protective circuit interrupts current flow in the battery, thereby preventing the battery from burning or exploding. 
     The protective circuit assembly  40  may include a sensor resistor, a charge/discharge FET element, a fuse, a controller, a temperature fuse, and the like. The electrical resistance of the PTC thermistor increases when the temperature of a battery is beyond a set value. Thus, when a battery has a high temperature, the PTC thermistor stops current flow. Since the operations of the PTC thermistor are reversible, the resistance of the PTC thermistor decreases when the temperature of a battery is lowered, so the current flow in the battery can resume. 
     The external connection terminal is a connection point for external devices. The external connection terminal may include a data input/output terminal, a power source terminal, a ground terminal, and the like. When a battery is connected to an external device through the external connection terminal, a discharge operation can occur. When a battery is connected to a charger through the external connection terminal, a charge operation can occur. 
     The protective circuit board  41  is positioned between the holder  30  and the cover  50 . Grooves  47  are formed in edges of the protective circuit board  41 , corresponding to the first and second fastening portions  37  and  513 , such that the first fastening portions  37  are easily joined to the second fastening portions  513 , inside of the cover  50 . The grooves  47  may guide the connection of the first and second fastening portions  37  and  513 . The grooves  47  may not be formed, depending on the positions of the first fastening portions  37  and the second fastening portions  513 . Holes may be formed in place of the grooves  47 . 
     The first and second lead terminals  43  and  45  connect the protective circuit board  41  to the negative and positive electrode terminals  13  and  15 . The first lead terminal  43  is connected to the negative electrode terminal  13 , and the second lead terminal  45  is connected to the electrode plate  15 . 
     When the can  11  serves as an electrode terminal (the electrode plate  15  is not included), the second lead terminal  45  can be connected to the can  11 . The upper portion  23  of the insulating member  20 , or a washer, is interposed between the first lead terminal  43  and the upper surface of the bare cell  10 , to insulate them from each other. When the insulating member  20  is adhesive, the first lead terminal  43  is adhered to the bare cell  10 , so as to be connected to the negative electrode terminal  13 . In addition, the lower portion  25  of the insulating member  20  is interposed between the second lead terminal  45  and the lower surface of the bare cell  10 , so that the second lead terminal  45  is adhered to the bare cell  10 , so as to be connected to the positive electrode terminal  15 . 
     The cover  50  includes a side cover  51 , an upper cover  53 , and a lower cover  55 . The side cover  51  covers the side surface of the bare cell  10 , to which the protective circuit board  41  and the holder  30  are adhered. Terminal holes  511  are formed in the cover, at positions corresponding to the external connection terminals of the protective circuit assembly  40 , such that the external connection terminals are exposed there through. The second fastening portions  513  are formed inside the side cover  51  and are joined to the first fastening portions  37 , so that the holder  30  and the cover  50  are joined together. 
     Referring to  FIGS. 2A through 2C , the second fastening portions  513  define openings into which the first fastening portions  37  can be inserted. Each second fastening portion  513  has a wedge-shaped portion that interlocks with the wedge-shaped portion of the first fastening portion  37 . Therefore, the second fastening portion  513  interlocks with the first fastening portion  37 . Since the second fastening portions  513  are joined to the first fastening portions  37 , inside the side cover  51 , it is possible to prevent a defective appearance, due to external protrusions. 
     It will be apparent that the shape and position of the second fastening portions  513  is not limited to those described herein. It will be readily understood by those skilled in the art that various modifications and changes can be made, such that the first and second fastening portions  37  and  513  can be joined together inside of the side cover  51 . 
     The upper and lower covers  53  and  55  cover the upper and lower surfaces of the bare cell  10 , respectively. Although the second fastening portion  513  is shown to be formed inside of the side cover  51 , the second fastening portion  513  may alternatively be formed in other regions of the cover  50 , depending on the shape of the holder  30  and the cover  50 . 
     The cover  50  may be formed by integrally forming the side, upper, and lower covers  51 ,  53 , and  55  using a material such as plastic, or the like. The bare cell  10  and the protective circuit assembly  40  can be joined to the cover  50  using a shrink-fit method. Alternatively, the cover  50  may be formed, by individually forming the side, upper, and lower covers  51 ,  53 , and  55 , and then joining the same together. 
     Alternatively, the cover  50  may be formed by attaching the side, upper, and lower covers  51 ,  53 , and  55  to the side, upper, and lower surfaces of the bare cell  10 , and then injecting a hot melting resin between the side cover  51  and the bare cell  10 , so that the cover  50  is joined to the bare cell  10 . 
     After the cover  50  is attached to the bare cell  10 , the label  60  may be attached to the outside of the bare cell  10  and the cover  50 . The label  60  can be an adhesive label, or may be a shrink-wrap type film. 
       FIG. 3  is an exploded perspective view of a battery pack  300 , according to an exemplary embodiment of the present invention.  FIG. 4A  is a perspective view of a holder and a cover of  FIG. 3 , before the holder is joined to the cover.  FIG. 4B  is a perspective view of the holder joined to the cover  50 ′, and  FIG. 4C  is a cross-sectional view taken along line B-B′ of  FIG. 4B . 
     Referring to  FIG. 3 , the battery pack  300  includes a bare cell  10 , a holder  30 ′, a protective circuit assembly  40 ′, and a cover  50 ′. The battery pack can further include an insulating member  20  disposed between the bare cell  10  and the holder  30 ′. 
     After joining the bare cell  10 , the holder  30 ′, the protective circuit assembly  40 ′, and the cover  50 ′ a label  60  can be attached to the battery pack  300 . Since the bare cell  10 , the insulating member  20 , and the label  60  are similar to those of the battery pack  100 , a detailed description thereof, is omitted. 
     The holder  30 ′ can include a seating portion  31  contacting a side surface of the bare cell  10  and support portions  33  extending perpendicularly from edges of the seating portion  31 , thereby forming a receiving portion  35  to receive the protective circuit assembly  40 ′. The holder  30 ′ includes a plurality of first fastening portions  39 . The first fastening portions  39  are joined to second fastening portion  515  of the cover  50 ′, which will be described later. 
     Referring to  FIGS. 4A through 4C , the first fastening portions  39  are formed on a surface of the seating portion  31 , between both support portions  33 . The first fastening portions  39  protrude from the seating portion  31 . The fastening portions  39  are cylindrical tubes. 
     The first fastening portions  39  have narrowed openings that are smaller than the second fastening portions  515 . The openings have inclined surfaces, so that the second fastening portions  515  can be easily inserted into the first fastening portions  39 . An inner diameter of the first fastening portions  39  is larger than a diameter of the first fastening portion  39 . The first fastening portions  39  interlock with the second fastening portions  515 . 
     The second fastening portions  515  are joined to the first fastening portions  39 , inside of the cover  510 , such that they do not affect the external appearance of the battery pack  300 . The shape and position of the first fastening portions  39  can be altered, so long as the first and second fastening portions  39  and  515  interlock within the cover  50 ′. 
     The protective circuit assembly  40 ′ includes a protective circuit, a protective circuit board  41 ′ on which electric elements, such as PTC thermistor, and external connection terminals are mounted, and first and second lead terminals  43  and  45 . The protective circuit, the first lead terminal  43 , and the second lead terminal  45  are similar to those of the battery pack  100 , so a detailed description thereof is omitted. 
     The protective circuit board  41 ′ includes holes  49  formed at positions corresponding to the first and second fastening portions  39  and  515 . The first and second fastening portions  39  and  515  are joined together through the holes  49 . The holes  49  may not be formed, depending on the positions of the first fastening portions  39  and the second fastening portions  515 . Grooves may be formed in place of the holes  49 . 
     The cover  50 ′ includes a side cover  51 ′, an upper cover  53 , and a lower cover  55 . The second fastening portions  515  are formed inside the side cover  51 ′, so as to be joined to the first fastening portions  39 , and thereby connect the holder  30 ′ and the cover  50 ′. 
     Referring to  FIGS. 4A through 4C , the second fastening portion  515  includes a body portion  515   a  and a head portion  515   b . The head portion  515   b  is larger than the body portion  515   a . The body portion  515   a  may be cylindrical, polygonal, or the like. 
     The head portion  515   b  has a “+”-shaped center cut. The head portion  515   b  is constricted when it is inserted into the opening of the first fastening portion  39 , and then returns to its original shape, after it is completely inserted in to the first fastening portion  39 . The second fastening portion  515  is thereby secured in the first fastening portion  39 . Since the first and second fastening portions  39  and  515  are joined inside of the side cover  51 ′, it is possible to maintain the appearance of the battery pack  300 . It will be readily understood by those skilled in the art that various modifications and changes can be made to the shape of the second fastening portion  515 , such that the first and second fastening portions  39  and  515  can be joined together inside the side cover  51 ′. 
     Although a few exemplary embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in theses exemplary embodiments, without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.