Abstract:
A secondary battery includes an electrode assembly; a case accommodating the electrode assembly; a cap plate sealing the electrode assembly within the case; a terminal plate on the cap plate and electrically connected to the electrode assembly; and an insulation member between and contacting the cap plate and the terminal plate, wherein the insulation member has a peripheral flange that extends away from the terminal plate.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of U.S. Provisional Application No. 61/826,444, filed on May 22, 2013 in the U.S. Patent and Trademark Office, the entire content of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field 
     One or more embodiments of the present invention relate to a secondary battery. 
     2. Description of the Related Art 
     In general, unlike primary batteries which are not rechargeable, a secondary battery is both dischargeable and rechargeable. A secondary battery is used as an energy source of, for example, a mobile device, an electric vehicle, a hybrid vehicle, an electric bicycle or an uninterruptible power supply (UPS). Based on the type of external device used with the batteries, a single secondary battery may be used or a battery module in which a plurality of batteries are bundled up by electrically connecting the batteries may be used. 
     SUMMARY 
     One or more embodiments of the present invention include a secondary battery in which an electric short circuit between different polarities of the secondary battery caused by intruding foreign substances may be prevented. 
     According to one or more embodiments of the present invention, a secondary battery includes: a cap plate sealing an electrode assembly; a terminal plate disposed on the cap plate and electrically connected to the electrode assembly; an insulation member formed between the cap plate and the terminal plate; and a short circuit preventing portion that is formed on at least one of the terminal plate and the insulation member and prevents an electrical short circuit due to a foreign material intruding between the terminal plate and the cap plate. 
     For example, the short circuit preventing portion may be formed on the insulation member. 
     For example, the insulation member may be formed to surround the terminal plate, and the short circuit preventing portion may be formed on an upper surface of the insulation member formed on the outer portion of the terminal plate. 
     For example, the short circuit preventing portion may include a protrusion upwardly protruding from the upper surface of the insulation member. 
     For example, the short circuit preventing portion may be formed in the form of a closed loop along a boundary of the insulation member surrounding the terminal plate. 
     For example, the protrusion of the short circuit preventing portion may protrude up to the same height as the terminal plate. 
     For example, the short circuit preventing portion may include an inclined upper surface of the insulation member. 
     For example, the upper surface of the insulation member may be downwardly inclined toward the terminal plate. 
     For example, the upper surface of the insulation member may be inwardly inclined in order to limit a flow of a foreign material within the terminal plate. 
     For example, the short circuit preventing portion may be formed in the form of a closed loop along a boundary of the insulation member surrounding the terminal plate. 
     For example, the short circuit preventing portion may include a stepped side surface of the insulation member. 
     For example, the side surface of the insulation member may include an upper side portion and a lower side portion, wherein the insulation member may have an overhang structure in which the upper side portion protrudes outwards more than the lower side portion. 
     For example, the short circuit preventing portion may comprise a first short circuit preventing portion having an inclined upper surface of the insulation member, a second short circuit preventing portion in the form of a protrusion protruding from the upper surface of the insulation member, and a third short circuit preventing portion having a stepped side surface. 
     For example, the short circuit preventing portion may be formed on the terminal plate. appreciate 
     For example, the short circuit preventing portion may comprise a groove portion formed in the terminal plate. 
     For example, the short circuit preventing portion may be formed in a boundary area adjacent to the insulation member. 
     For example, the short circuit preventing portion may comprise a first short circuit preventing portion having a groove portion formed in the terminal plate and a second short circuit preventing portion formed to surround the terminal plate. 
     For example, the second short circuit preventing portion may include at least one of an inclined upper surface of the insulation member, a protrusion protruding from the upper surface of the insulation member, and a stepped side surface of the insulation member. 
     According to the embodiments of the present invention, an electric short circuit between different polarities of a secondary battery caused by intrusion of a foreign substance such as salt water may be prevented. For example, in a salt water spray test in which salt water is sprayed on a secondary battery, the salt water dropping on a terminal plate may flow on a cap plate, and accordingly, a short circuit path might be formed from the terminal plate to the cap plate due to ion conduction but a short circuit preventing portion according to the embodiments of the present invention prevents formation of a short circuit path, thereby preventing a short circuit between different polarities and a malfunction of a secondary battery due to this short circuit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a secondary battery according to an embodiment of the present invention; 
         FIG. 2  is an exploded perspective view of the secondary battery illustrated in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the secondary battery of  FIG. 1  cut along a line III-III; 
         FIGS. 4A and 4B  illustrate a portion of a secondary battery including a short circuit preventing portion according to an embodiment of the present invention; 
         FIGS. 5A and 5B  illustrate a portion of a secondary battery including a short circuit preventing portion according to another embodiment of the present invention; 
         FIGS. 6A and 6B  illustrate a portion of a secondary battery including a short circuit preventing portion according to another embodiment of the present invention; 
         FIGS. 7A and 7B  illustrate a portion of a secondary battery including a short circuit preventing portion according to another embodiment of the present invention; 
         FIGS. 8A and 8B  illustrate a portion of a secondary battery including an insulation member according to another embodiment of the present invention; 
         FIGS. 9 and 10  illustrate a portion of a secondary battery including an insulation member according to another embodiments of the present invention; 
         FIGS. 11A and 11B  illustrate a portion of a secondary battery including an insulation member according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. 
       FIG. 1  is a perspective view of a secondary battery according to an embodiment of the present invention.  FIG. 2  is a disassembled perspective view of the secondary battery illustrated in  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , a pair of electrode terminals, that is, first and second electrode terminals  110  and  120  which have opposite polarities may protrude from the secondary battery. For example, the first and second electrode terminals  110  and  120  are electrically connected to an electrode assembly  150  accommodated in the secondary battery, and the first and second electrode terminals  110  and  120  are respectively electrically connected to first and second electrode plates of the electrode assembly  150  to thereby supply discharge power accumulated in the secondary battery to the outside or to function as a positive electrode terminal or a negative electrode terminal in order to receive charging power from the outside. For example, the first and second electrode terminals  110  and  120  may be formed on two portions of the secondary battery. 
     According to another embodiment of the present invention, a cap plate  100  of the secondary battery may be electrically connected to the electrode assembly  150  to function as a terminal, and in this case, one of the first and second electrode terminals  110  and  120  may be omitted. 
       FIG. 3  is a cross-sectional view of the secondary battery of  FIG. 1  cut along a line III-III according to an embodiment of the present invention. Referring to  FIG. 3 , the secondary battery includes the electrode assembly  150 , the first and second electrode terminals  110  and  120 , and collector members  117  and  127  through which the electrode assembly  150  and the first and second electrode terminals  110  and  120  are electrically connected to each other. Also, the secondary battery may include a case  180  accommodating the electrode assembly  150  and the cap plate  100  encapsulating an opening portion of the case  180 , in which the electrode assembly  150  is accommodated. The cap plate  100  is coupled to an upper end of the case  180 , in which the electrode assembly  150  is accommodated, and may encapsulate the opening portion of the case  180 . For example, the cap plate  100  and the case  180  may be coupled to each other via welding along an edge of the cap plate  100 . 
     In one embodiment, the cap plate  100  may include a vent portion  108 , which fractures to relieve internal pressure if the internal pressure of the case  180  exceeds a previously set point, and an encapsulation unit  109  that encapsulates an electrolyte solution inlet. 
     The electrode assembly  150  may be accommodated in the case  180  of the secondary battery, and may include first and second electrode plates  151  and  152  having opposite polarities and a separator  153  located between the first and second electrode plates  151  and  152 . The electrode assembly  150  may be a winding type in which the first and second electrode plates  151  and  152  and the separator  153  are wound up in the form of a jelly roll, or a stack type in which the first and second electrode plates  151  and  152  and the separator  153  are alternately stacked. The cap plate  100  may be assembled at an upper opening portion of the case  180 , in which the electrode assembly  150  is accommodated, and for electrical connection between the electrode assembly  150  and an external circuit or between the electrode assembly  150  and another adjacent secondary battery, the first and second electrode terminals  110  and  120  that are electrically connected to the electrode assembly  150  may be formed on an outer portion of the cap plate  100 . 
     The first and second terminals  110  and  120  may have different polarities and may be electrically connected to the first electrode plate  151  and the second electrode plate  152  of the electrode assembly  150 , respectively. 
     The first electrode terminal  110  may include a first collector terminal  115  and a first terminal plate  111  coupled to the first collector terminal  115 . Similarly, the second electrode terminal  120  may include a second collector terminal  125  and a second terminal plate  121  coupled to the second collector terminal  125 . Hereinafter, the collector terminals  115  and  125  may refer both to the first and second collector terminals  115  and  125  or selectively either the first collector terminal  115  or the second collector terminal  125 . Also, the terminal plates  111  and  121  may refer both to the first and second terminal plates  111  and  121  or selectively either the first terminal plate  111  or the second terminal plate  121 . As will be described later, the first and second collector terminals  115  and  125  are respectively coupled to first and second collector members  117  and  127 ; the collector members  117  and  127  may refer to both the first and second collector members  117  and  127  or selectively either the first collector member  117  or the second collector member  127 . 
     The first and second collector terminals  115  and  125  may pass through the cap plate  100  to be withdrawn out of the cap plate  100 . Accordingly, a terminal hole  100 ′ may be formed in the cap plate  100 , into which the collector terminals  115  and  125  are inserted to be assembled. In detail, the first and second collector terminals  115  and  125  are inserted upwardly, in a direction from a lower portion to an upper portion of the cap plate  100 , and may be inserted to pass through the terminal hole  100 ′ of the cap plate  100 . 
     The first and second collector terminals  115  and  125  may include first and second collector terminal fixing portions  115   a  and  125   a  respectively formed in upper and lower portions of the collector terminals  115  and  125  along a length direction, and may include first and second collector terminal flange portions  115   b  and  125   b . For example, the first and second collector terminals  115  and  125  may be assembled to pass through the cap plate  100 , and may include the first and second collector terminal fixing portions  115   a  and  125   a  exposed above the cap plate  100  and first and second collector terminal flange portions  115   b  and  125   b  located below the cap plate  100 . 
     The first and second collector terminal fixing portions  115   a  and  125   a  are included to fix positions of the first and second collector terminals  115  and  125 , and may be fixed to upper surfaces of the first and second terminal plates  111  and  121  by using a riveting method. For example, the first and second collector terminal fixing portions  115   a  and  125   a  are in a flange form that extend laterally from a main body of the first and second collector terminals  115  and  125 , and may be fixed to the upper surfaces of the first and second terminal plates  111  and  121 . A groove that is concavely indented according to pressurization of a processing tool which rotates at a high speed may be formed in an upper end portion of the collector terminal fixing portions  115   a  and  125   a , and as the upper end portion of the collector terminal fixing portions  115   a  and  125   a  are pulled to the side according to pressurization of the processing tool, the first and second collector terminal fixing portions  115   a  and  125   a  may be closely adhered to the upper surfaces of the terminal plates  111  and  121 . 
     The first and second collector terminal flange portions  115   b  and  125   b  may have a flange shape that is extended over an outer diameter of the terminal hole  100 ′ so that the collector terminals  115  and  125  do not disengage from the terminal hole  100 ′ of the cap plate  100 . In one embodiment, the collector terminals  115  and  125  are assembled to be inserted into the terminal hole  100 ′ from the lower portion of the cap plate  100 , and positions of the collector terminals  115  and  125  may be fixed by riveting the collector terminal fixing portions  115   a  and  125   a  exposed above the cap plate  100  while they are supported under the cap plate  100  via the collector terminal flange portions  115   b  and  125   b.    
     The collector terminals  115  and  125  may be inserted into the terminal hole  100 ′ of the cap plate  100  while being electrically insulated from the cap plate  100 . For example, first and second seal gaskets  113  and  123  may be inserted into the terminal hole  100 ′, and as the collector terminal  115  and  125  are inserted with the seal gaskets  113  and  123  located between the seal gaskets  113  and  123 , the collector terminals  115  and  125  may be insulated from the cap plate  100 . The seal gaskets  113  and  123  seal a portion around the terminal hole  100 ′ to prevent leakage of an electrolyte solution contained in the case  180  and seal the case to prevent intrusion of external impurities. 
     First and second lower insulation members  114  and  124  may be located between the collector terminals  115  and  125  and the cap plate  100 ; the lower insulation members  114  and  124  may insulate the collector terminals  115  and  125  from the cap plate  100 . Thus, by locating the seal gaskets  113  and  123  around the terminal hole  100 ′ through which the collector terminals  115  and  125  pass, and locating the lower insulation members  114  and  124  between the collector terminals  115  and  125  and the cap plate  100 , the collector terminals  115  and  125  and the cap plate  100  may be insulated from each other. 
     In one embodiment, the lower insulation members  114  and  124  may seal the portion around the terminal hole  100 ′, together with the seal gaskets  113  and  123 , thereby preventing leakage of an electrolyte solution and intrusion of external impurities. The lower insulation members  114  and  124  may also be extended between the collector members  117  and  127  and the cap plate  100 . 
     The collector terminals  115  and  125  may be electrically connected to the electrode assembly  150  via the collector members  117  and  127 . The collector members  117  and  127  may include first and second collector plates  117   b  and  127   b  that comprise a lower portion of the collector members  117  and  127  and are coupled to the electrode assembly  150  and lead portions  117   a  and  127   a  that comprise an upper portion of the collector members  117  and  127  and are coupled to the collector terminals  115  and  125 . 
     The collector plates  117   b  and  127   b  may be coupled to two side edges of the electrode assembly  150 , and may be coupled by welding to a non-coated portion formed at an edge of the electrode assembly  150 , that is, a non-coated portion of each of the first and second electrode plates  151  and  152  where no electrode active material is formed. For example, the first collector plate  117   b  may be coupled to a non-coated portion of the first electrode plate  151 , and the second collector plate  127   b  may be coupled to a non-coated portion of the second electrode plate  152 . 
     The lead portions  117   a  and  127   a  may be portions that are extended from and bent with respect to the collector plates  117   b  and  127   b  so as to face the collector terminals  115  and  125 , and terminals holes  117 ′ and  127 ′ may be formed for coupling of the collector terminals  115  and  125  (see  FIG. 2 ). For example, lower end portions of the collector terminals  115  and  125  may be respectively inserted into the terminal holes  117 ′ and  127 ′ of the lead portions  117   a  and  127   a , and the collector terminals  115  and  125  and the lead portions  117   a  and  127   a  may be assembled to face each other. Also, the collector terminals  115  and  125  and the lead portions  117   a  and  127   a  may be coupled by welding portions around the terminal holes  117 ′ and  127 ′ where they contact each other. 
     The terminal plates  111  and  121  may be located on the cap plate  100 . The terminal plates  111  and  121  are electrically connected to the collector terminals  115  and  125 , and may provide a relatively broad terminal area extending over the collector terminals  115  and  125 . The terminal plates  111  and  121  may be connected to the collector terminals  115  and  125  (in detail, the collector terminal fixing portions  115   a  and  125   a ) via riveting, but the embodiments of the present invention are not limited thereto; for example, the terminal plates  111  and  121  may be connected to collector terminals by using various methods such as welding or screw coupling. 
     An insulation member  112  may be located between the first terminal plate  111  and the cap plate  100 . The insulation member  112  may insulate the first terminal plate  111  from the cap plate  100 . 
     According to an embodiment of the present invention, one of the first and second terminal plates  111  and  121 , for example, the second terminal plate  121 , and the cap plate  100  may have the same polarity, and in this case, an insulation member may be omitted between the second terminal plate  121  and the cap plate  100 . 
     According to another embodiment of the present invention, the second terminal plate  121  and the cap plate  100  may have different polarities. For example, the cap plate  100  may have neither a positive polarity nor a negative polarity but may be insulated from both a positive polarity or a negative polarity and be electrically neutral. In one embodiment, in order to insulate the first and second terminal plates  111  and  121  from the cap plate  100 , a pair of insulation members surrounding the first and second terminal plates  111  and  121  may be provided. 
     According to an embodiment of the present invention, a short circuit preventing portion S 1  is formed on the insulation member  112  and/or the terminal plate  111 . The short circuit preventing portion S 1  formed on the insulation member  112  and/or the terminal plate  111  may be selectively formed on one of the insulation member  112  and the terminal plate  111  or both the insulation member  112  and the terminal plate  111 . 
     The short circuit preventing portion S 1  may prevent an electrical short circuit between the terminal plate  111  and the cap plate  100 , which is caused by foreign materials located between the terminal plate  111  and the cap plate  100 . For example, the short circuit preventing portion S 1  blocks formation of a short circuit path from the terminal plate  111  to the cap plate  100 , thereby preventing an electrical short circuit via the short circuit preventing portion S 1  so that no short circuit path is formed due to foreign materials such as salt between the terminal plate  111  and the cap plate  100  having different polarities. For example, in a salt water spray test in which salt water is sprayed on a secondary battery, when salt water dropping on the terminal plate  111  flows onto the cap plate  100 , a short circuit path may be formed from the terminal plate  111  onto the cap plate  100  due to ion conduction, and a malfunction may be caused due to electricity flowing between different polarities of the secondary battery. 
     The short circuit preventing portion S 1  may be formed on the terminal plate  111  or the insulation member  112  surrounding a boundary of the terminal plate  111 , thereby blocking an electrical short circuit path from the terminal plate  111  to the cap plate  100  due to foreign materials having an electrical conductivity, such as salt water. 
     For example, when a liquid foreign material flows downward due to gravity, a short circuit path may be formed between the terminal plate  111  and the cap plate  100 , and in order to prevent formation of this short circuit path, a short circuit preventing portion S 1  in the form of a step for blocking a continuous flow of a foreign material, in the form or a protrusion, or in the form of a groove portion for blocking a flow of a foreign material by accommodating the flow may be formed on the terminal plate  111  or on the insulation member  112  surrounding the boundary of the terminal plate  111 . The short circuit preventing portion S 1  will be described in detail below. 
       FIGS. 4A and 4B  illustrate a short circuit preventing portion S 1  according to an embodiment of present invention.  FIG. 4B  is a cross-sectional view cut along a line IV-b of  FIG. 4A . 
     Referring to  FIGS. 4A and 4B , the short circuit preventing portion S 1  is formed on the insulation member  112  surrounding the terminal plate  111 . In detail, the insulation member  112  surrounds a periphery of the terminal plate  111  from the outside and the short circuit preventing portion S 1  in the form of a step may be formed on a side of the insulation member  112 . 
     For example, a side surface  112   c  of the insulation member  112  is a portion of the insulation member  112  that covers a side  111   c  of the terminal plate  111 , and may be a portion of the insulation member  112  covering the side  111   c  of the terminal plate that connects an upper surface  111   a  of the terminal plate  111  exposed to the outside and a lower surface  111   b  of the terminal plate  111  that faces the cap plate  100 . 
     For example, the short circuit preventing portion S 1  may be formed on the external side surface  112   c  of the insulation member  112  opposite to the terminal plate  111 . The short circuit preventing portion S 1  may cut off a continuous flow of a foreign material flowing along the external side surface  112   c  of the insulation member  112 , thereby preventing a short circuit between the terminal plate  111  and the cap plate  100 . 
     For example, the short circuit preventing portion S 1  may have a step shape between an upper side portion  112   a  and a lower side portion  112   b . For example, the insulation member  112  may have an overhang structure in which the upper side portion  112   a  protrudes outwards more than the lower side portion  112   b . In other words, the short circuit preventing portion S 1  in the form of a step may be formed as the upper side portion  112   a  protrudes outwards in an opposite direction from the terminal plate  111  more than the side lower portion  112   b . A liquid foreign material flowing along the upper side portion  112   a  is not able to flow along the lower side portion  112   b  which is inwardly stepped, and thus, the continuous liquid flow may be cut. 
     For example, the short circuit preventing portion S 1  may have a closed loop form along the entire side surface  112   c  of the insulation member  112 . Because the short circuit preventing portion S 1  surrounds the boundary of the terminal plate  111 , the flow of foreign materials flowing from the terminal plate  111  in any direction may be effectively blocked. 
       FIGS. 5A and 5B  illustrate a short circuit preventing portion S 2  according to another embodiment of present invention.  FIG. 5B  is a cross-sectional view cut along a line V-b of  FIG. 5A . 
     Referring to  FIGS. 5A and 5B , the short circuit preventing portion S 2  may be formed on an insulation member  212  formed to surround a terminal plate  111 . In detail, the insulation member  212  surrounds the terminal plate  111  from the outside, and the short circuit preventing portion S 2  may be formed on an upper surface  212   a  of the insulation member  212  formed on the outer portion of the terminal plate  111 . For example, the upper surface  212   a  of the insulation member  212  may refer to a surface formed on the same side as an upper surface  111   a  of the terminal plate  111  exposed to the outside. 
     The short circuit preventing portion S 2  may be formed on the upper surface  212   a  of the insulation member  212 , and may have an inclined surface formed on the insulation member  212 . For example, the upper surface  212   a  of the insulation member  212  may be inclined toward an inner portion of the insulation member  212  where the terminal plate  111  is located. That is, the short circuit preventing portion S 2  may be downwardly inclined toward the terminal plate  111 . Accordingly, a flow of a foreign material on the upper surface  212   a  of the insulation member  212  flows to the terminal plate  111  but does not flow to the cap plate  100  on an outer portion of the terminal plate  111 . Accordingly, the flow of the foreign material may be limited inside the terminal plate  111 , and the flow of the foreign material flowing to the cap plate  100  on the outer portion of the terminal plate  111  may be blocked. Consequently, an electrical short circuit between the terminal plate  111  and the cap plate  100  may be prevented. 
     While the short circuit preventing portion S 2  formed of the inclined surface is illustrated as an oblique plane in  FIG. 5B , the embodiments of the present invention are not limited thereto; the short circuit preventing portion S 2  may also be a round and curved surface. 
     The short circuit preventing portion S 2  may be in the form of a rim along a boundary of the insulation member  212 . The short circuit preventing portion S 2  may be in the form of a closed loop along the boundary of the insulation member  212  to surround the terminal plate  111 , thereby blocking a flow of a foreign material flowing from the upper surface  111   a  of the terminal plate  111  in any direction. 
       FIGS. 6A and 6B  illustrate a short circuit preventing portion S 3  according to another embodiment of present invention.  FIG. 6B  is a cross-sectional view cut along a line VI-b of  FIG. 6A . 
     Referring to  FIGS. 6A and 6B , the short circuit preventing portion S 3  is formed on an insulation member  312  surrounding a terminal plate  111 . In detail, the insulation member  312  surrounds a periphery of the terminal plate  111  from the outside, and the short circuit preventing portion S 3  in the form of a protrusion may be formed on an upper surface  312   a  of the insulation member  312  formed in an outer portion of the terminal plate  111 . 
     For example, an upper surface of the insulation member  312  may refer to a surface formed on the same side as an upper surface  111   a  of the terminal plate  111  exposed to the outside. The short circuit preventing portion S 3  may be formed in the form of a rim along a boundary of the insulation member  312 . 
     The short circuit preventing portion S 3  may be formed in the form of a closed loop along the boundary of the insulation member  312  to surround the terminal plate  111 , thereby blocking a flow of a foreign material flowing from the upper surface  111   a  of the terminal plate  111  in any direction. 
     Because the short circuit preventing portion S 3  is formed in the form of a protrusion upwardly protruding from the upper surface  312   a  of the insulation member  312 , a flow of a foreign material flowing from the terminal plate  111  may be blocked, and an electrical short circuit caused due to the flow of the foreign material may be prevented. For example, the short circuit preventing portion S 3  may function as a dam that blocks a flow of a foreign material, or even when a foreign material overflows the short circuit preventing portion S 3 , the short circuit preventing portion S 3  in the form of a protrusion cuts the continuous flow of the foreign material, thereby preventing an electrical short circuit caused due to the continuous flow of the foreign material such as salt water. 
     For example, a protrusion height H 2  of the short circuit preventing portion S 3  may be the same as a height H 1  of the terminal plate  111  or higher. The short circuit preventing portion S 3  which is formed at a height equal to or higher than the terminal plate  111  may prevent a liquid foreign material such as salt water from flowing down from the terminal plate  111 . 
       FIGS. 7A and 7B  illustrate a short circuit preventing portion S 4  according to another embodiment of present invention.  FIG. 7B  is a cross-sectional view of the secondary battery cut along a line VII-b of  FIG. 7A . 
     Referring to  FIGS. 7A and 7B , the short circuit preventing portion S 4  is formed on a terminal plate  211 . For example, the short circuit preventing portion S 4  may be formed in a boundary area of the terminal plate  211  adjacent to an insulation member  412 . 
     The short circuit preventing portion S 4  may include a groove portion formed in the terminal plate  211 . The short circuit preventing portion S 4  may be formed in the form of a groove, which is capable of accommodating a flow of a foreign material, so as to block the flow of the foreign material that is about to flow from the terminal plate  211  to the insulation member  412 . Accordingly, an electrical short circuit due to the flow of the foreign material flowing from the terminal plate  211  onto the cap plate  100  may be blocked. 
     The short circuit preventing portion S 4  may be formed to a depth extending from an exposed upper surface  211   a  of the terminal plate  211  toward a lower surface  211   b  facing the cap plate  100 , and may be formed along a side surface  211   c  of the terminal plate  211 . According to another embodiment of the present invention, the short circuit preventing portion S 4  may be formed to a depth to pass through the terminal plate  211 , that is, up to the lower surface  211   b  of the terminal plate  211 . 
     The short circuit preventing portion S 4  may be selectively formed in a portion along a boundary of the terminal plate  211  or may be formed in the form of a closed loop along the entire boundary of the terminal plate  211 . For example, as illustrated in  FIG. 7A , the terminal plate  211  may have a rectangular shape including a pair of short side portions and a pair of long side portions, or the short circuit preventing portion S 4  may be selectively formed on one pair of short side portions. However, the short circuit preventing portion S 4  according to the embodiments of the present invention is not limited thereto, and may also be formed in the form of a closed loop along the rectangular boundary of the terminal plate  211 . 
     At least two of the short circuit preventing portions S 1 , S 2 , and S 3  having different forms illustrated in  FIGS. 4A, 5A, and 6A  may be formed in combination on one of the insulation members  112 ,  212 , and  312 .  FIGS. 8A, 8B, 9, 10, 11A, and 11B  respectively illustrate insulation members  512 ,  612 ,  712 , and  812  according to embodiments of the present invention. Hereinafter, a structure in which at least two different short circuit preventing portions among short circuit preventing portions S 21 , S 22 , S 31 , S 32 , S 41 , S 42 , S 51 , S 52 , and S 53  are combined on one insulation member will be described with reference to  FIGS. 8A, 8B, 9, 10, 11A, and 11B . 
       FIGS. 8A and 8B  illustrate an insulation member  512  according to an embodiment of the present invention.  FIG. 8B  is a cross-sectional view of  FIG. 8A . 
     Short circuit preventing portions S 21  and S 22  illustrated in  FIGS. 8A and 8B  may comprise a first short circuit preventing portion S 21  having an inclined upper surface  512   a  and a second short circuit preventing portion S 2  in the form of a protrusion protruded from the upper surface  512   a  of the insulation member  512 . For example, a flow of a foreign material may be limited within a terminal plate  311  via the inclined surface of the first short circuit preventing portion S 21  and the protrusion of the second short circuit preventing portion S 22 , and the flow of the foreign material to an outer portion of the terminal plate  311  may be blocked. 
       FIG. 9  illustrates an insulation member  612  according to another embodiment of the present invention. 
     Short circuit preventing portions S 31  and S 32  illustrated in  FIG. 9  may comprise a first short circuit preventing portion S 31  having an inclined upper surface  612   a  and a second short circuit preventing portion S 32  having a stepped side surface  612   c . For example, a flow of a foreign material may be limited within a terminal plate  311  via the inclined surface of the first short circuit preventing portion S 31 , and even if the foreign material flows along the side surface  612   c  of the insulation member  612 , a continuous flow of the foreign material may be blocked via the stepped side surface  612   c  of the second short circuit preventing portion S 32 . 
       FIG. 10  illustrates an insulation member  712  according to another embodiment of the present invention. 
     Short circuit preventing portions S 41  and S 42  illustrated in  FIG. 10  may comprise a first short circuit preventing portion S 41  in the form of a protrusion protruding from an upper surface  712   a  of the insulation member  712  and a second short circuit preventing portion S 42  having a stepped side surface  712   c . For example, a flow of a foreign material may be limited within a terminal plate  311  via the protrusion of the first short circuit preventing portion S 41 , and even if the foreign material flows along a side surface of the insulation member  712 , a continuous flow of the foreign material may be blocked via the stepped side surface  712   c  of the second short circuit preventing portion S 42 . 
       FIGS. 11A and 11B  illustrate an insulation member  812  according to another embodiment of the present invention.  FIG. 11B  is a cross-sectional view of the insulation member  812  of  FIG. 11A . 
     Short circuit preventing portions S 51 , S 52 , and S 53  illustrated in  FIGS. 11A and 11B  may comprise a first short circuit preventing portion S 51  having an inclined upper surface  812   a , a second short circuit preventing portion S 52  in the form of a protrusion protruding from the upper surface  812   a  of the insulation member  812 , and a third short circuit preventing portion S 53  having a stepped side surface  812   c . For example, a flow of a foreign material may be limited within a terminal plate  311  via the inclined upper surface  812   a  of the first short circuit preventing portion S 51  and the protrusion of the second short circuit preventing portion S 52 , and even if the foreign material flows along the side surface  812   c  of the insulation member  812 , a continuous flow of the foreign material may be blocked via the stepped side surface  812   c  of the third short circuit preventing portion S 53 . 
     In one embodiment, the secondary batteries illustrated in  FIGS. 8A, 8B, 9, 10, 11A, and 11B  may further include a short circuit preventing portion S 11  of the terminal plate  311  in addition to the short circuit preventing portions S 21 , S 22 , S 31 , S 32 , S 41 , S 42 , S 51 , S 52 , and S 53  of the insulation members  512 ,  612 ,  712 , and  812 . 
     That is, according to the embodiments illustrated in  FIGS. 8A, 8B, 9, 10, 11A, and 11B , the short circuit preventing portions S 11 , S 21 , S 22 , S 31 , S 32 , S 41 , S 42 , S 51 , S 52 , and S 53  may comprise the short circuit preventing portions S 11  formed on the terminal plate  311  and the short circuit preventing portions S 21 , S 22 , S 31 , S 32 , S 41 , S 42 , S 51 , S 52 , and S 53  formed on the insulation members  512 ,  612 ,  712 , and  812 . In each of the embodiments of the present invention, the short circuit preventing portion S 11  which is in the form of a groove formed on the terminal plate  311  may provide accommodation space for accommodating a flow of a foreign material in the terminal plate  311 , and as the flow of the foreign material from the terminal plate  311  toward the insulation members  512 ,  612 ,  712 , and  812  is accommodated, the flow of the foreign material flowing along the cap plate  100  is blocked via the short circuit preventing portion S 11 . Consequently, an electrical short circuit between the terminal plate  311  and the cap plate  100  may be prevented. Moreover, as the short circuit preventing portions S 21 , S 22 , S 31 , S 32 , S 41 , S 42 , S 51 , S 52 , and S 53  are further formed on the insulation members  512 ,  612 ,  712 , and  812  which surrounds the terminal plate  311 , the flow of the foreign material flowing along the insulation members  512 ,  612 ,  712 , and  812  may be blocked, and a short circuit between the terminal plate  311  and the cap plate  100  may be prevented. 
     For example, according to the embodiment illustrated in  FIGS. 8A and 8B , the short circuit preventing portions S 11 , S 21 , and S 22  may comprise a first short circuit preventing portion S 21  having the inclined upper surface  512   a  of the insulation member  512 , a second short circuit preventing portion S 22  in the form of a protrusion protruding from the upper surface  812   a  of the insulation member  812 , and a third short circuit preventing portion S 11  in the form of a groove portion formed in the terminal plate  311 . The third short circuit preventing portion S 11  may be formed to a predetermined depth from an upper surface  311   a  of the terminal plate  311 . 
     For example, according to the embodiment of  FIG. 9 , the short circuit preventing portions S 11 , S 21 , and S 22  may comprise a first short circuit preventing portion S 21  having the inclined upper surface  512   a  of the insulation member  512 , a second short circuit preventing portion S 22  in the form of a protrusion protruding from the upper surface  812   a  of the insulation member  812 , and a third short circuit preventing portion S 11  in the form of a groove portion formed in the terminal plate  311 . 
     For example, according to the embodiment of  FIG. 10 , the short circuit preventing portions S 11 , S 41 , and S 42  may comprise a first short circuit preventing portion S 41  in the form of a protrusion protruding from the upper surface  712   a  of the insulation member  712  and a second short circuit preventing portion S 42  having the stepped side surface  712   c  of the insulation member  712 , and a third short circuit preventing portion S 11  in the form of a groove portion formed in the terminal plate  311 . 
     For example, according to the embodiment of  FIGS. 11A and 11B , the short circuit preventing portions S 11 , S 51 , S 52 , and S 53  may comprise a first short circuit preventing portion S 51  having the inclined upper surface  812   a  of the insulation member  812 , a second short circuit preventing portion S 52  in the form of a protrusion protruding from the upper surface  812   a  of the insulation member  812 , and a third short circuit preventing portion S 11  having the stepped side surface  812   c , and a fourth short circuit preventing portion S 11  in the form of a groove portion formed in the terminal plate  311 . 
     In one embodiment, while not shown in the drawings, the short circuit preventing portions S 1 , S 2 , and S 3  of the insulation members  112 ,  212 , and  312  illustrated in  FIGS. 4A, 5A, and 6A  and the short circuit preventing portion S 4  of the terminal plate  211  illustrated in  FIG. 7A  may be applied in combination to a single secondary battery, and illustration and description of detailed structures thereof will be omitted here. 
     In one embodiment, according to an embodiment of the present invention, the first terminal plates  111 ,  211 , and  311  and the cap plate  100  have different polarities, and the second terminal plate  121  and the cap plate  100  may have the same polarity. Accordingly, the short circuit preventing portions S 21 , S 22 , S 31 , S 32 , S 41 , S 42 , S 51 , S 52 , and S 53  may be formed on the first terminal plate  111 ,  211 , and  311  and/or the insulation members  112 ,  212 ,  312 ,  412 ,  512 ,  612 ,  712 , and  812  surrounding the first terminal plate  111 ,  211 , and  311 , thereby preventing an electrical short circuit between the first terminal plate  111 ,  211 , and  311  and the cap plate  100 . In this case, as the second terminal plate  121  and the cap plate  100  have the same polarity, a short circuit preventing portion may be omitted in the second terminal plate  121 . 
     According to another embodiment of the present invention, the first terminal plate  111 ,  211 , and  311  and the second terminal plate  121  may both have a different polarity from the cap plate  100 . Here, the short circuit preventing portion S 1 , S 2 , S 3 , S 4 , S 11 , S 21 , S 22 , S 31 , S 32 , S 41 , S 42 , S 51 , S 52 , and S 53  may be formed on the first terminal plate  111 ,  211 , and  311  in order to prevent an electrical short circuit between the first terminal plate  111 ,  211 , and  311  and the cap plate  100 . In addition, another short circuit preventing portions S 1 , S 2 , S 3 , S 4 , S 11 , S 21 , S 22 , S 31 , S 32 , S 41 , S 42 , S 51 , S 52 , and S 53  may be formed on the second terminal plate  121  in order to prevent an electrical short circuit between the second terminal plate  121  and the cap plate  100 . That is, a pair of short circuit preventing potions S 1 , S 2 , S 3 , S 4 , S 11 , S 21 , S 22 , S 31 , S 32 , S 41 , S 42 , S 51 , S 52 , and S 53  may be formed on the first and second terminal plates  111 ,  211 ,  311 , and  212 . The pair of the short circuit preventing potions S 1 , S 2 , S 3 , S 4 , S 11 , S 21 , S 22 , S 31 , S 32 , S 41 , S 42 , S 51 , S 52 , and S 53  formed on the first and second terminal plates  111 ,  211 ,  311 , and  212  may have various structures as described above, and the pair of the short circuit preventing potions S 1 , S 2 , S 3 , S 4 , S 11 , S 21 , S 22 , S 31 , S 32 , S 41 , S 42 , S 51 , S 52 , and S 53  may have the same structure or different structures. 
     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. 
     
       
         
               
             
               
               
             
               
             
               
               
             
               
             
           
               
                   
               
               
                 Explanation of Reference numerals 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 100: cap plate 
                 110: first electrode terminal 
               
               
                 111, 211, 311: first terminal plate 
                 121: second terminal plate 
               
             
          
           
               
                 112, 212, 312, 412, 512, 612, 712, 812: insulation member 
               
             
          
           
               
                 113, 123: seal gasket 
                   
               
               
                 114, 124: lower insulation member 
                 115, 125: collector terminal 
               
               
                 115a, 125a: collector terminal 
                 115b, 125b: collector terminal 
               
               
                 fixing portion  
                 flange portion 
               
               
                 117, 127: collector member 
                 117a, 127a: lead portion 
               
               
                 117b, 127b: collector plate 
                 150: electrode assembly 
               
               
                 151: first electrode plate 
                 152: second electrode plate 
               
               
                 153: separator 
                 120: second electrode terminal 
               
               
                 H1: height of terminal plate 
                 H2: height of short circuit preventing 
               
               
                   
                 portion 
               
             
          
           
               
                 S1, S2, S3, S4, S11, S21, S22, S31, S32, S41, S42, S51, S52, S53: short 
               
               
                 circuit preventing portion