Abstract:
A battery module includes a plurality of unit batteries, each including a positive terminal and a negative terminal which protrude outside of each unit battery and which have bent terminal portions, and a connection member which electrically connects the unit batteries with each other and which includes a fixing plate fixed to the bent terminal portions of adjacent unit batteries by welding so as to improve productivity and provide high stability.

Description:
CLAIM OF PRIORITY 
     This application is a continuation of Applicant&#39;s Ser. No. 12/591,733 entitled BATTERY MODULE WITH PLURALITY OF BATTERIES HAVING BENT TERMINAL PORTIONS CONNECTED WITH FIXING PLATE filed in the U.S. Patent &amp; Trademark Office on Nov. 30, 2009, now issued U.S. Pat. No. 8,329,333, and assigned to the assignee of the above-captioned application. Furthermore, this application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119, §120 and/or §121 from the aforesaid Applicant&#39;s Ser. No. 12/591,733 and from an application earlier filed in the Korean Intellectual Property Office on Dec. 11, 2008 and there duly assigned Serial No. 10-2008-0126040. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a battery module, and more particularly, to a battery module having an improved structure in which rechargeable batteries are electrically connected to each other. 
     2. Description of the Related Art 
     Rechargeable batteries can be repeatedly charged and discharged, unlike primary batteries that cannot be repeatedly charged. Low-capacity rechargeable batteries are used for portable compact electronic apparatuses such as mobile phones, notebook computers, and camcorders, and high-capacity rechargeable batteries are widely used as a power source for driving a motor of a hybrid vehicle, etc. 
     A high-output rechargeable battery using a non-aqueous electrolyte having high energy density has been developed in recent years. The high-output rechargeable battery is configured with high capacity by connecting a plurality of rechargeable batteries in series so as to be used for driving a motor for an apparatus requiring a large amount of power, i.e., an electrical vehicle, etc. 
     Furthermore, one high-capacity rechargeable battery is constituted by a plurality of rechargeable batteries which are connected to each other in series. The rechargeable batteries may have a cylindrical shape, a prismatic shape, and so forth. 
     The prismatic-shaped rechargeable battery includes an electrode assembly which has a positive electrode and a negative electrode with a separator interposed therebetween, a case having a space incorporating the electrode assembly, a cap plate which seals the case and has a terminal hole into which an electrode terminal is inserted, and an electrode terminal which is electrically connected with the electrode assembly and is inserted into the terminal hole to protrude outside of the case. 
     The rechargeable batteries are electrically connected with each other by a connection plate to constitute a battery module. The electrode terminal is fixed to the cap plate by a nut coupled to an upper portion of the electrode terminal, the connection plate is joined onto the nut, and the nut is joined onto the connection plate, such that the connection plate and the electrode terminal are electrically connected to each other. 
     However, a structure of fixing the connection plate with the nut is vulnerable to external vibration or shock. That is, when the nut is loosened by vibration or shock, electrical contact between the electrode terminal and the connection plate is deteriorated. 
     In order to solve the above-mentioned problem, a structure is proposed in which the electrode terminal is formed in a plate shape and the connection plate is fixed to the electrode terminal by welding, etc. However, this structure has a difficulty of welding each electrode terminal. Furthermore, after the connection plate is installed in the electrode terminal, the welding is performed. At this time, a jig for fixing the connection plate to the electrode terminal must be installed. As such, when each electrode terminal is welded in a state in which the jig is installed, the process is complicated and productivity is deteriorated. 
     In addition, the electrode terminal and the connection plate use materials having high electrical conductivity in order to suppress generation of heat and minimize loss of electric power. However, since these materials have high thermal conductivity as well as high electrical conductivity, welding heat is too rapidly transferred, such that the welding is very difficult and the quality of the welded part is deteriorated. In particular, when the welding is performed by a comparatively easy resistance welding scheme, resistance is small and transfer of the heat is rapid, such that the welding becomes very difficult. If arc welding or the like, other than resistance welding, is adopted, the transfer of the heat is rapid, such that melting does not normally occur and the welding process becomes inefficient. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
     SUMMARY OF THE INVENTION 
     An exemplary embodiment of the present invention has been made in an effort to provide a battery module which is capable of stably connecting rechargeable batteries. 
     An exemplary embodiment of the present invention provides a battery module which includes a plurality of unit batteries including a positive terminal and a negative terminal which protrude outside and have bent terminal portions, and a connection member which electrically connects the unit batteries with each other, and which includes a fixing plate fixed to bent terminal portions of adjacent unit batteries by welding. 
     The electrode terminal may include a protruding terminal portion and a bent terminal portion bent from the protruding terminal portion. The bent terminal portion formed in the positive terminal and the bent terminal portion formed in the negative terminal may be bent in different directions. 
     Grooves may be formed at a bent edge of the electrode terminal such that the bent terminal portion is easily bent. The connection member may include a fixing portion fixed to the bent terminal portions of the positive and negative terminals by welding, and a supporting portion which is bent from the fixing portion and is in contact with the protruding terminal portion. 
     A projection portion which is in contact with a top surface of the electrode terminal may be formed in the supporting portion. A projection portion which is in contact with the top surface of the electrode terminal may be formed in the fixing portion. 
     A welding plate having greater electrical resistance than that of the connection member may be installed between the connection member and the bent terminal portion. The welding plate may be made of a material having a lower melting point than that of the connection member. 
     The connection member may be fixed to the positive terminal and the negative terminal by resistance welding. The connection member may be made of a hetero-junction metal (clad metal). A metal disposed on a surface of the connection member, which faces the bent terminal portion, may have greater electrical resistance than that of a metal disposed on a surface of the connection member which faces a direction opposite thereto. The metal disposed on the surface of the connection member, which faces the bent terminal portion, may have a lower melting point than that of the metal disposed on the surface of the connection member which faces the direction opposite thereto. 
     According to an exemplary embodiment of the present invention, bent terminal portions are formed in a positive terminal and a negative terminal and the connection member is fixed to the bent terminal portion by welding, such that the connection member can be easily welded to the positive terminal and the negative terminal. Therefore, productivity is improved. 
     Furthermore, the connection member is fixed to the terminals by welding, such that electrical contact between the connection member and the terminals can be prevented from being deteriorated due to external vibration or shock. 
     Since a welding plate is installed between the connection member and the terminals, the connection member can be easily welded to the terminals, such that welding quality becomes excellent. Therefore, the overall stability of a battery module is improved. 
     Since a projection is formed in the connection member, the connection member can be easily welded to the terminals without an additional jig. 
     Since the connection member is made of a hetero-junction metal, weldability between the connection member and the terminals can be improved. As a result, electrical contact between the connection member and the terminals is prevented from being deteriorated due to external vibration or shock, thereby improving the stability of the battery module. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, in which like reference symbols indicate the same or similar components, wherein: 
         FIG. 1  is a perspective view of a rechargeable battery according to a first exemplary embodiment of the present invention; 
         FIG. 2  is a perspective view of the rechargeable battery of  FIG. 1  having a positive terminal and a negative terminal which are bent; 
         FIG. 3  is an exploded perspective view of rechargeable batteries and a connection member according to the first exemplary embodiment of the present invention; 
         FIG. 4  is a transverse cross-sectional view of a state in which members shown in  FIG. 3  are coupled to each other; 
         FIG. 5  is a perspective view of the connection member according to the first exemplary embodiment of the present invention; 
         FIG. 6  is a cross-sectional view illustrating a process in which the connection member is bonded to the positive terminal and the negative terminal by welding according to the first exemplary embodiment of the present invention; 
         FIG. 7  is a perspective view of a battery module according to the first exemplary embodiment of the present invention; 
         FIG. 8  is a perspective view of a connection member adopted in a battery module according to a second exemplary embodiment of the present invention; and 
         FIG. 9  is a perspective view of a connection member adopted in a battery module according to a third exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown so as to be realized by those skilled in the art. However, the present invention may be modified in various ways, all without departing from the spirit or scope of the present invention, and the invention is not limited to embodiments described hereafter. In addition, like reference numerals denote like elements in the specification and the accompanying drawings. 
       FIG. 1  is a perspective view of a rechargeable battery according to a first exemplary embodiment of the present invention, and  FIG. 2  is a perspective view of the rechargeable battery of  FIG. 1  having a positive terminal and a negative terminal which are bent. 
     Referring to  FIGS. 1 and 2 , the rechargeable battery  10  includes a case  14  having an inner space, a cap plate  17  coupled to an opening of the case  14 , and a positive terminal  11  and a negative terminal  12  which protrude from the top of the cap plate  17 . 
     The rechargeable battery  10  according to the exemplary embodiment, as a prismatic-shaped rechargeable battery, may include a lithium ion rechargeable battery, a nickel hydrogen rechargeable battery, or a lithium polymer rechargeable battery. 
     The case  14  has a hexahedral shape extending substantially in one direction. The case  14  has an inner space and an opening (not shown) formed at one end thereof. In the exemplary embodiment, although the hexahedral prismatic-shaped rechargeable battery has been exemplified, the present invention is not limited thereto, and the case may have various shapes, such as a cylindrical shape, etc. 
     An electrode assembly (not shown), which is repeatedly charged and discharged depending on flow of ions, is inserted into the case  14 . The cap plate  17  is coupled to the opening to thereby seal the case  14 . 
     The cap plate  17  is formed of a thin plate. An electrolyte inlet, into which an electrolytic solution is injected, is formed in the cap plate  17 , and a sealing cap  18  is installed in the electrolyte inlet. Furthermore, a vent portion  19  having a groove, which may be fractured depending on an internal set pressure, is installed in the cap plate  17 . 
     The positive terminal  11  and the negative terminal  12  are electrically connected to the electrode assembly and protrude outside of the cap plate  17 . 
     As shown in  FIG. 1 , after the positive terminal  11  and the negative terminal  12  are formed in a flat panel shape, the positive terminal  11  and the negative terminal  12  are bent as shown in FIG.  2 . 
     The positive terminal  11  includes a protruding terminal portion  11   a  which is vertically erected on a top surface of the cap plate  17  and a bent terminal portion  11   b  which is bent at the protruding terminal portion  11   a . A groove or notch  11   c  is formed in a curved terminal portion  11   d  which is between the bent terminal portion  11   b  and the protruding terminal portion  11   a  such that the bent terminal portion  11   b  can be easily bent. 
     Similarly, the negative terminal  12  also includes a protruding terminal portion  12   a  which is vertically erected on the top surface of the cap plate  17 , and a bent terminal portion  12   b  which is bent at the protruding terminal portion  12   a . A groove or notch  12   c  is formed in a curved terminal portion  12   d  which is between the bent terminal portion  12   b  and the protruding terminal portion  12   a  such that the bent terminal portion  12   b  can be easily bent. 
     The grooves or notches  11   c  and  12   c  are formed at upper and lower ends of the curved terminal portion  11   d  and  12   d , respectively. Therefore, the bent terminal portions  11   b  and  12   b  can be easily bent at a predetermined position. The bent terminal portions  11   b  and  12   b  are bent so as to be substantially perpendicular to the protruding terminal portions  11   a  and  12   a , respectively. That is, the detailed view shown in  FIG. 2  may be described by recognizing a line L 1 , which crosses the grooves or notches  11   c  formed at the upper and lower ends of the curved terminal portion  11   d , and a line L 2 , which crosses the grooves or notches  12   c  formed at the upper and lower ends of the curved terminal portion  12   d . The lines L 1  and L 2  are perpendicular to the surface of the rechargeable battery  10 , on which the positive terminal  11  and the negative terminal  12  are formed. The bent terminal portions  11   b  and  12   b  of the positive and negative terminals  11  and  12 , respectively, are bent in opposite directions relative to each other. 
       FIG. 3  is an exploded perspective view of rechargeable batteries and a connection member according to the first exemplary embodiment of the present invention, and  FIG. 4  is a transverse cross-sectional view of a state in which members shown in  FIG. 3  are coupled to each other. 
     Referring to  FIGS. 3 and 4 , rechargeable batteries  10  and  20  are arranged at a predetermined interval, and the positive terminal  11  of one rechargeable battery  10  and the negative terminal  12  of the other rechargeable battery  20  are disposed adjacent to each other. 
     At this point, the bent terminal portion  11   b  of the positive terminal  11  is bent toward the negative terminal  12  and the bent terminal portion  12   b  of the negative terminal  12  is bent toward the positive terminal  11 . The bent terminal portions  11   b  and  12   b  of the positive and negative terminals  11  and  12 , respectively, are disposed adjacent to each other on the same plane at a predetermined interval. 
     In this state, a welding plate  40  and a connection member  30  are sequentially stacked on the bent terminal portions  11   b  and  12   b . The connection member  30  includes a fixing portion  31  which is in close contact with the welding plate  40  and a supporting portion  35  which is bent at both sides of the fixing portion  31 , and which is in close contact with the protruding terminal portions  11   a  and  12   a . The welding plate  40 , positioned between the fixing portion  31  and the bent terminal portions  11   b  and  12   b , is made of a material having large electrical resistance, and is in close contact with the bent terminal portions  11   b  and  12   b.    
       FIG. 5  is a perspective view of the connection member according to the first exemplary embodiment of the present invention. 
     Referring to  FIG. 5 , the fixing portion  31  according to the exemplary embodiment has a substantially flat panel shape, and the supporting portion  35  has a flat panel shape which is bent in a perpendicular direction from both sides of the fixing portion  31 . A projection portion  35   a  protruding toward the supporting portion opposite the projection portion is formed at an upper end of the supporting portion  35 , and is supported on upper ends of the positive terminal  11  or the negative terminal  12 . 
     As such, when the supporting portion  35  is formed, the connection member  30  can be installed at an accurate position in a horizontal direction, and the supporting portion  35  is in close contact with the protruding terminal portions  11   a  and  12   a , thereby increasing the electrical contact area. Furthermore, when the projection portion  35   a  is formed, the connection member  30  can be installed at an accurate position in a vertical direction. As a result, since an additional jig for supporting the connection member  30  is not required at the time of welding the connection member  30 , the manufacturing process is simplified, thereby improving productivity. 
       FIG. 6  is a cross-sectional view illustrating a process in which the connection member is bonded to the positive terminal and the negative terminal by welding according to the first exemplary embodiment of the present invention. 
     Referring to  FIG. 6 , in a state in which the welding plate  40  and the connection member  30  are sequentially installed in the positive terminal  11  and the negative terminal  12 , a first welding rod  51  is positioned at the fixing portion  31  of the connection member  30 , and two second welding rods  54  are positioned at the bent terminal portions  11   b  and  12   b  of the positive terminal  11  and the negative terminal  12 . In this state, the connection member  30  is bonded to the positive terminal  11  and the negative terminal  12  through resistance welds  53  by applying a current. As such, according to the exemplary embodiment, the connection member  30  can be attached to the positive terminal  11  and the negative terminal  12  by one-time resistance welding. 
     The welding plate  40  is made of a material having electrical resistance which is larger than, and a melting point which is lower than, those of the connection member  30 . As a result, since a large resistance and a large amount of heat are generated on the welding plate  40  at the time of the resistance welding, the connection member  30  and the positive and negative terminals  11  and  12 , respectively, can be easily melted. Furthermore, the welding plate  40  having a low melting point is further melted in comparison with the connection member  30 , and serves as an adhesive for bonding the positive and negative terminals  11  and  12  to the connection member  30 . Accordingly, the connection member  30  can be more stably attached to the positive and negative terminals  11  and  12 , respectively. 
       FIG. 7  is a perspective view of a battery module according to the first exemplary embodiment of the present invention. 
     Referring to  FIG. 7 , in a state in which the plurality of rechargeable batteries  10  and  20  are disposed at predetermined intervals, after the connection member  30  is installed in the positive terminal  11  of one rechargeable battery  10  and the negative terminal  12  of the rechargeable battery  20  adjacent thereto, the positive terminal  11  and the negative terminal  12  are electrically connected to each other by bonding the connection member  30  and the positive and negative terminals  11  and  22  through welding, such that the rechargeable batteries  10  and  20  are connected to each other in series to form a battery module  100 . 
     The connection member  30  is attached to the positive terminal  11  and the negative terminal  12  by welding, such that it is possible to prevent electrical contact between the connection member  30  and the positive and negative terminals  11  and  12 , respectively, from being deteriorated due to external shock or vibration. Since the melted welding plate  40  serves as the adhesive, the connection member  30  is fixed to the positive and negative terminals  11  and  12 , respectively, more stably. 
       FIG. 8  is a perspective view of a connection member adopted in a battery module according to a second exemplary embodiment of the present invention. 
     The battery module according to the exemplary embodiment has the same structure as the battery module according to the first exemplary embodiment except for the structure of the connection member. Therefore, the same components will not be repeatedly described. 
     Referring to  FIG. 8 , the connection member  60  according to the exemplary embodiment includes a fixing portion  61  and a projection portion  62  which is bent to one side at an upper end of the fixing portion  61 . 
     The fixing portion  61  has a substantially rectangular flat panel shape. The projection portion  62  is configured by bending the upper end of the fixing portion  61 . The fixing portion  61  is in close contact with the bent terminal portions  11   b  and  12   b  of the positive and negative terminals  11  and  12 , respectively. The projection portion  62  is supported on upper ends of the bent terminal portions  11   b  and  12   b.    
     Meanwhile, the connection member  60  according to the exemplary embodiment is made of a hetero junction metal (clad metal). The connection member  60  may have a structure in which nickel and copper are joined to each other, or a structure in which aluminum and copper are joined to each other. 
     At this point, a part made of nickel or aluminum is in close contact with the bent terminal portions  11   b  and  12   b , and a part made of copper is disposed in a direction opposite thereto. Nickel and aluminum have greater resistance than, and a lower melting point than, copper. Therefore, when the connection member  60  is made of the hetero junction metal, the connection member  60  can be easily attached to the positive terminal  11  and the negative terminal  12  by welding without the welding plate interposed between the connection member  60  and the positive and negative terminals  11  and  12 , respectively. 
       FIG. 9  is a perspective view of a connection member adopted in a battery module according to a third exemplary embodiment of the present invention. 
     Referring to  FIG. 9 , a connection member  70  according to the exemplary embodiment includes a fixing portion  71  having a rectangular flat panel shape, and upper projection portions  72  and side projection portions  74  which protrude from the fixing portion  71 . 
     Two upper projection portions  72  are separated from each other at an upper end of the fixing portion  71 , and side projection portions  74  protrude from respective sides of the fixing portion  71 . 
     The upper projection portions  72  and the side projection portions  74  protrude from the same surfaces. The upper projection portions  72  and the side projection portions  74  are supported on the positive and negative terminals  11  and  12 , respectively, such that the connection member  70  can be installed at an accurate position. 
     While the invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.