Abstract:
An electrode assembly for a rechargeable battery resists external impacts applied to the rechargeable battery, and includes a sealing tape attached to an outer circumference of the rechargeable battery, which extends toward an upper part and a lower part to prevent the electrode assembly from unfastening, and a top insulating plate and a bottom insulating plate may be attached to the extended portion of the sealing tape. A shock resistant electrode assembly for a rechargeable battery has an insulating plate attached thereto by an extended portion of a sealing tape, thereby preventing the electrode assembly from moving in a battery housing when an external impact is applied.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an electrode assembly for a rechargeable battery, a rechargeable battery using the electrode assembly, and a fabricating method thereof. More particularly, the present invention relates to an electrode assembly for a rechargeable battery, which may prevent the electrode assembly from moving in a battery housing, e.g., a can, by not allowing the electrode assembly to unfasten when an external impact is applied. 
         [0003]    2. Description of the Related Art 
         [0004]    In general, as portable electronic apparatuses, e.g., video cameras, mobile phones, portable computers, etc., have continued to progress and become more light weight with increased high technology content, extensive research in the field of rechargeable batteries used as power sources has been made. Rechargeable batteries may include, e.g., a nickel-cadmium batteries, a nickel-metal hydride batteries, a nickel-zinc batteries, lithium rechargeable batteries, etc. Among these types of batteries, the lithium rechargeable batteries, which may be made in a small size with a high capacity, have come into widespread use in the field of high-tech electronics due to advantages which may include high operation voltage and high energy density per unit weight. 
         [0005]    An electrode assembly in a can, i.e., a container, may transform or rotate when an external impact, e.g., from a dropped battery, is applied to the lithium rechargeable battery. Lithium rechargeable batteries which are being used for electric tools may possibly have the upper part and the lower part of the electrode assembly transform or deteriorate from vibrations transferred to the lithium rechargeable battery when the electric tool is operating. 
         [0006]    Workers may also handle electric tools carelessly, and the possibility of electrode assembly damage may thus increase. Transformation or dislocation of the upper and lower part of the electrode assembly may generate a short circuit, and the increased internal resistance may cause a problem by generating heat. 
         [0007]    One safety test for a battery is a drum test for determining whether an electrode assembly is transformed, dislocated or rotated by measuring the internal resistance, after the battery is moved up, down, right and left in the octagon-shaped drum. When the battery undergoes the drum test, the electrode assembly is moved up and down, and the welded region of an electrode tab may be deintercalated, thereby substantially increasing internal resistance. As a result, there is a need for new battery electrode technologies that address and overcome the problems and shortcomings of prior art batteries. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention is therefore directed to an electrode assembly for a rechargeable battery and a method for making thereof, which substantially overcomes one or more of the problems due to the limitations and disadvantages of the related art. 
         [0009]    It is therefore a feature of an embodiment of the present invention to provide an electrode assembly that does not move in a battery housing in response to an external impact. 
         [0010]    It is therefore a feature of an embodiment of the present invention to prevent transformation or damage to an electrode assembly by movement of the electrode assembly. 
         [0011]    It is therefore a feature of an embodiment of the present invention to prevent an internal short circuit due to transformation or damage of an electrode assembly. 
         [0012]    It is therefore a feature of an embodiment of the present invention to prevent a welded region of an electrode tab from deintercalating, thereby preventing internal resistance from increasing. 
         [0013]    It is therefore a feature of an embodiment of the present invention to manufacture a battery suitable as a power supply for electric tools, which generate large vibrations. 
         [0014]    At least one of the above and other features and advantages of the present invention may be realized by providing an electrode assembly for rechargeable battery which may include a positive electrode plate, a negative electrode plate and a separator between the positive electrode and the negative electrode, and the separator may include sealing tape attached a circumference of the electrode assembly, and at least one insulating plate may be positioned on at least one of an upper part or a lower part of the electrode assembly, and the insulating plate may be fixed to the electrode assembly by the sealing tape. 
         [0015]    The insulating plate may include an upper surface, a lower surface and a side surface, and the sealing tape may be attached to the side of the insulating plate. The sealing tape may extend longer than the length of the electrode assembly in at least one of an upper direction or in a lower direction. The sealing tape may extend as far as a thickness of the insulating plate installed on the upper part of the electrode assembly when extending to the upper part of the electrode assembly, and the sealing tape may extend as much as the thickness of the insulating plate installed on the lower part of the electrode assembly when extending to the lower part of the electrode assembly. Multiple holes may be formed on the insulating plate. The electrode assembly may be applied to a cylinder-shaped rechargeable battery. The insulating plate may be formed from polyolefin. 
         [0016]    At least one of the above and other features and advantages of the present invention may be realized by providing a rechargeable battery that may include an electrode assembly, a battery housing receiving the electrode assembly and a cap assembly sealing the battery housing. Sealing tape may be attached to a circumference of the electrode assembly, and at least one insulating plate may be placed at least one of an upper part or a lower part of the electrode assembly, and the insulating plate may be fixed to the electrode assembly by the sealing tape. 
         [0017]    At least one of the above and other features and advantages of the present invention may be realized by providing a method for fabricating a rechargeable battery which may include positioning at least one insulating plate on at least one of an upper part or a lower part of an electrode assembly, attaching a sealing tape to a side of the insulating plate and to a circumference of the electrode assembly, inserting the electrode assembly having the sealing tape into a battery housing, and sealing the battery housing by sealing an upper opening of the battery housing with a cap assembly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which: 
           [0019]      FIG. 1  illustrates a longitudinal sectional view of a lithium rechargeable battery according to an exemplary embodiment of the present invention; 
           [0020]      FIG. 2  illustrates a perspective view of an electrode assembly in  FIG. 1 ; 
           [0021]      FIG. 3  illustrates an A-A′ cross-sectional view of  FIG. 2 ; and 
           [0022]      FIG. 4  illustrates a flow chart of stages of a fabricating method of a rechargeable battery according to an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    Korean Patent Application No. 10-2006-0027528, filed on Mar. 27, 2006, in the Korean Intellectual Property Office, and entitled: “Electrode Assembly for Rechargeable Battery and Rechargeable Battery Using It, and the Fabricating Method Thereof,” is incorporated by reference herein in its entirety. 
         [0024]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are illustrated. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
         [0025]    In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Further, it will be understood that when a layer is referred to as being “under” another layer, it can be directly under, and one or more intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Like reference numerals refer to like elements throughout. 
         [0026]    The rechargeable battery of the present invention may have an advantage of preventing an electrode assembly from moving when external impacts such as vibrations are applied, since a top insulating plate and a bottom insulating plate are fixed respectively to the upper part and the lower part of an electrode assembly by sealing tape. 
         [0027]    The present invention may prevent an electrode assembly from transforming or deforming due to the electrode assembly movement, thus preventing an internal short circuit from occurring due to the electrode assembly transformation of deformation. 
         [0028]    The present invention may additionally have the advantage of preventing internal resistance of a battery from increasing by not allowing the welded region of an electrode tab to become detached. 
         [0029]    In addition, the present invention may have the advantage that the battery is applicable to powering electric tools, which generate large vibrations when operating. 
         [0030]    Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
         [0031]      FIG. 1  illustrates a longitudinal sectional view of a lithium rechargeable battery according to one exemplary embodiment of the present invention,  FIG. 2  illustrates a perspective view of an electrode assembly in  FIG. 1 , and  FIG. 3  illustrates a cross-sectional view thereof along line A-A′ of  FIG. 2 . 
         [0032]    Referring to  FIG. 1 , a lithium rechargeable battery  200  may include an electrode assembly  205 , a can  240  and a cap assembly  280 . The can  240  may also be referred to as a battery housing  240 . The lithium rechargeable battery  200  may be formed in a cylinder shape. However, the shape is not restricted to a cylinder shape and any other shape, e.g., a button shape, may be used. 
         [0033]    Referring to  FIG. 2  and  FIG. 3 , the electrode assembly  205  may be formed to include a positive electrode plate  210 , a negative electrode plate  220  and a separator  230 . A top insulating plate  234  may be placed on the upper part of the electrode assembly  205 , and a bottom insulating plate  232  may be placed on the lower part of the electrode assembly  205 . Sealing tape  236  may be attached to the circumference of the electrode assembly  205 , and the electrode assembly  205  may be formed to include a positive electrode tab  215  and a negative electrode tab  225 . 
         [0034]    The positive electrode plate  210  may include a positive electrode collector, a positive electrode coating portion and a positive electrode non-coating portion. The positive electrode collector may be formed of a conductive metallic material which may gather electrons from a positive electrode coating portion and transfer them to an external circuit. The positive electrode coating portion may be made by mixing a positive electrode active material, a conductive material and a binder, and the mixture may be coated at a predetermined thickness on the positive electrode collector. In the positive electrode collector, the positive electrode non-coating portion may be the portion in which a positive electrode coating portion is not formed, and the positive electrode tab  215  may be welded to one side of the positive electrode non-coating portion. 
         [0035]    The negative electrode plate  220  may include a negative electrode collector, a negative electrode coating portion and a negative electrode non-coating portion. The negative electrode collector may be formed of a conductive metallic material which may gather electrons from a negative electrode coating portion and transfer them to an external circuit. 
         [0036]    The negative electrode coating portion may be made by mixing a negative electrode active material, a conductive material and a binder, and the mixture may be coated at a predetermined thickness on the negative electrode collector. In the negative electrode collector, the negative electrode non-coating portion may be the portion in which a negative electrode active material layer is not formed, and the negative electrode tab  225  may be welded to one side of the negative electrode non-coating portion. 
         [0037]    The separator  230  may be interposed between the positive electrode plate  210  and the negative electrode plate  220 , and the separator  230  may expand or extend to cover the outer circumference of the electrode assembly  205 . The separator  230  may serve to prevent a short circuit of the positive electrode plate  210  and the negative electrode plate  220 . The separator  230  may be formed of a porous polymer material that may pass lithium ions. 
         [0038]    The positive electrode tab  215  and the negative electrode tab  225  may be respectively welded to a positive electrode non-coating portion and a negative electrode non-coating portion, thereby coupling the electrode assembly  205  and another part of the battery. The positive electrode tab  215  and the negative electrode tab  225  may be welded by, e.g., resistance welding, and a lamination tape may be attached to the welded portion to prevent short circuits and heating. The welding method of the positive electrode tab  215  and the negative electrode tab  225  is not limited, and any suitable welding method may be used. 
         [0039]    The top insulating plate  234  may be placed between the electrode assembly  205  and the cap assembly  280  to prevent a short circuit. The bottom insulating plate  232  may be placed between the electrode assembly  205  and a lower plate  242  of the can  240 , thereby preventing a short circuit. Here, the top insulating plate  234  and the bottom insulating plate  232  may be formed to respectively include an upper surface, a lower surface and a side surface. The upper surface and the lower surface may have a cylinder shape, and the side surface may have a circumferential shape of a flat cylinder. 
         [0040]    The top insulating plate  234  and the bottom insulating plate  232  may be made of a polyolefin, e.g., polyethylene (PE), polypropylene (PP), polybutylene (PB), copolymers thereof, etc. Multiple holes  235  may be formed in the top insulating plate  234  and the bottom insulating plate  232 . The holes  235  may be a path in which electrolyte may sink to an electrode assembly  205  when injecting electrolyte. As illustrated in  FIG. 2 , the holes  235  may include a center hole and at least one circumferential hole in a radial shape around the center hole. The number of patterns of the holes  235  is not limited, and any number of holes any suitable pattern may be used. Although seven radial holes  235  are illustrated in  FIG. 2 , any suitable number of holes may be used. 
         [0041]    The top insulating plate  234  and the bottom insulating plate  232  may be fixed to the electrode assembly  205  by utilizing sealing tape  236 . The sealing tape  236  may expand or extend to a predetermined length in relation to the height of the electrode assembly  205 . The sealing tape  236  may be longer than the thickness of the top insulating plate  234  and the bottom insulating plate  232 . 
         [0042]    The sealing tape  236  may expand or extend in an upper direction to have substantially the same thickness or extent of the top insulating plate  234 , and expand or extend in a lower direction to have substantially the same thickness or extent of the bottom insulating plate  232 . The side surfaces of the top insulating plate  234  and the bottom insulating plate  232  may only be attached to the sealing tape  236 . The edges of the sealing tape  236  may be substantially flush with the surface of the top insulating plate  234  and the bottom insulating plate  232 . The sealing tape  236  may provide a cushioning effect to the top insulating plate  234  and the bottom insulating plate  232  to thus protect the internal battery and electrode structure from shocks and vibrations. 
         [0043]    In addition, the sealing tape  236  may be made of a polyolefin, e.g., polyethylene (PE), polypropylene (PP), polybutylene, (PB), copolymers thereof, etc., but the material of the sealing tape  236  is not limited hereto. The sealing tape  236  may be attached to the outermost region of the wound electrode assembly  205  to prevent the electrode assembly  205  from unfastening. The sealing tape  236  may fix the top insulating plate  234  and the bottom insulating plate  232  to an upper and a lower part of an electrode assembly  205 . 
         [0044]    The can  240  may be formed in a cylindrical shape including a side plate  241  and a lower plate  242 . The side plate  241  may include an outer circumference and inner circumference, which may form a concentric circle. The lower plate  242  may include a parallel aligned front surface and a back surface. 
         [0045]    An upper part of the can  240  may form a top opening through which an electrode assembly may be inserted, and through which electrolyte may be injected. 
         [0046]    A bottom insulating plate  232  may be inserted between the lower plate  242  of the can  240  and the electrode assembly  205  in order to insulate the can  240  and the electrode assembly  205 . The upper part of the can  240  may prevent the electrode assembly  205  from moving in the can  240  after the electrode assembly  205  is inserted. A bidding part  244  may be formed to safely seat the cap assembly  280 , and a creeping part  243  may be formed to seal the battery after the cap assembly  280  is inserted. 
         [0047]    The top insulating plate  234  may be inserted between the upper part of the electrode assembly  205  and the cap assembly  280  to insulate the electrode assembly  205  and the cap assembly  280 . The can  240  may be formed of aluminum or an alloy metal which may have light weight and have high malleability, but the material of the can  240  is not limited hereto. The can  240  may be preferably fabricated by, e.g., a deep drawing method, but the fabricating method of the can  240  is not limited hereto. 
         [0048]    The cap assembly  280  may include a safety band  261 , a current breaking element  272 , a secondary protective element  273 , and a top cap  274 . 
         [0049]    The safety band  261  may include a protrusion in the middle of the plate, which may protrude downward and may be positioned in the lower part of the cap assembly  280 . The protrusion may transform upward by the pressure generated in the rechargeable battery. The positive electrode tab  215 , which may be drawn or extend from the positive electrode plate  210 , may be welded to the lower surface of the safety band  261 , thereby coupling the safety band  261  and the positive electrode  210  of the electrode assembly  205 . The negative electrode tab  225 , which may be withdrawn or extend from the negative electrode plate  220 , may be welded to the lower plate  242  of the can  240 , thereby coupling the negative electrode plate  220  to the can  240 . The safety band  261  may deform or explode when a pressure in the can  240  increases, thereby damaging the current breaking element  272 . 
         [0050]    The current breaking element  272  may be positioned at the upper part of the safety band  261 , which may break down and isolate the current when the safety band  261  transforms or deforms. The secondary protective element  273  may be positioned at the upper part of the current breaking element  272 , in which current is blocked when overcurrent flows. The conductive top cap  274  may be positioned at the upper part of the secondary protective element  273 , which may provide the outside with a positive electrode voltage or a negative electrode voltage. The cap assembly  280  may include a gasket  250  to insulate the cap assembly  280  functioning as the positive electrode and the can  240  functioning as the negative electrode. 
         [0051]    As described above, the top insulating plate  234  and the bottom insulating plate  232  of the lithium rechargeable battery  200  may be respectively fixed to the upper part and the lower part of the electrode assembly  205  by sealing tape  236 , thereby preventing the electrode assembly  205  from moving when an external impact or vibrations is applied. This cell configuration may thus prevent the upper part and the lower part of the electrode assembly  205  from transforming or deforming. 
         [0052]    The fabricating method of a lithium rechargeable battery according to an exemplary embodiment of the present invention will be explained below. 
         [0053]      FIG. 4  illustrates a flow chart of a fabricating method of a rechargeable battery according to an exemplary embodiment of the present invention. Below, the top insulating plate  234  and the bottom insulating plate  232  will be referred to as insulating plates  234 ,  232  for convenience. 
         [0054]    Referring to  FIG. 4 , the fabricating method of a lithium rechargeable battery  200  may include stages of forming the electrode assembly (S 10 ), preparing the insulating plate (S 20 ), attaching sealing tape (S 30 ), inserting the electrode assembly (S 40 ), injecting electrolyte (S 50 ), and sealing the can (S 60 ). 
         [0055]    The stage of forming the electrode assembly (S 10 ) may include forming the electrode assembly  205  by winding the positive electrode plate  210 , the negative electrode plate  220 , and the separator  230  into a cylindrical configuration. The positive electrode tab  215  may be attached to the positive electrode non-coating portion of the positive electrode plate  210 , and the negative electrode tab  225  may be attached to the negative electrode non-coating portion of the negative electrode plate  220 . Then, they may be wound into an electrode assembly  205 . The stage of forming the electrode assembly (S 10 ) may be performed by a winding device. 
         [0056]    The stage of preparing the insulating plate (S 20 ) may include respectively positioning the top insulating plate  234  and the bottom insulating plate  232  at the upper part and the lower part of the electrode assembly  205 . 
         [0057]    The stage of attaching the sealing tape (S 30 ) may include attaching the sealing tape  236  to the side of the top insulating plate  234 , the side of the bottom insulating plate  232 , and circumference of the electrode assembly  205 . The sealing tape  236  may be attached to the upper part of the top insulating plate  234  and the lower part of the bottom insulating plate  232 . Although not shown in a drawing, sealing tape including multiple holes may be attached in order to help the electrolyte impregnate. 
         [0058]    The stage of inserting the electrode assembly (S 40 ) may include inserting the electrode assembly  205  having the sealing tape  236  attached into the inside of the can  240 . The top insulating plate  234  and the bottom insulating plate  232  may be respectively attached to the upper part and the lower part of the electrode assembly  205  by the sealing tape  236 . That is, it may be preferable, for a simplified process, to insert the electrode assembly  205 , which has insulating plates  234 ,  232  attached to the upper part and the lower part thereof, into the inside of the can  240 . 
         [0059]    The stage of injecting electrolyte (S 50 ) may include injecting electrolyte into the can  240 , in which the electrode assembly  205  has been inserted. To precisely control the amount of electrolyte injected, a method that measures the weight before and after of electrolyte injection may be used. 
         [0060]    The stage of sealing the can (S 60 ) may include sealing the upper opening of the can  240  with a cap assembly  280 . Because the positive electrode tab  215  may be smeared or coated with electrolyte when electrolyte is injected during stage (S 50 ) of injecting the electrolyte, the positive electrode tab  215  may be cleaned and then welded to the lower part of the safety band  261 . The creeping part  243  may be formed on the uppermost part of the can  240  to secure a hermetic seal, which may be followed by sealing the upper opening with the cap assembly  280 . 
         [0061]    Next, operation of a lithium rechargeable battery according to an exemplary embodiment of the present invention will be explained. 
         [0062]    Referring to  FIG. 1 , the lithium rechargeable battery  200  may include the electrode assembly  205  in which the top insulating plate  234  and the bottom insulating plate  232  may be respectively fixed to the upper part and the lower part thereof by sealing tape  236 . 
         [0063]    When the lithium rechargeable battery  200  passes through a drum test or is used for electric tools, the lithium rechargeable battery may receive substantial rotary power and/or vibrations from outside, and this rotary power and/or vibrations may be delivered to the electrode assembly  205  inserted inside the can  240 . 
         [0064]    When the top insulating plate  234  and the bottom insulating plate  232  are respectively fixed to the upper part and the lower part of the electrode assembly  205  by sealing tape  236 , the top insulating plate  234  and the bottom insulating plate  232  may play the role of a buffer to prevent the upper part and the lower part of the electrode assembly  205  from moving, deforming, and/or transforming. 
         [0065]    Exemplary embodiments of the present invention have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.