Patent Publication Number: US-2012040238-A1

Title: Conductive connecting structure for a core assembly of a secondary lithium battery

Description:
This application is a continuation in part of U.S. patent application Ser. No. 11/534,302, claims 1-3 of this application are new, and claims 1-5 of the U.S. patent application Ser. No. 11/534,302 have been cancelled. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electrical connection structure for a core assembly of a second lithium battery, and more particularly to a design of the connection between the core assembly inside the battery and the positive or negative lead terminal on the case of the battery. 
     2. Description of the Prior Art 
       FIG. 1  shows of a conventional electrode assembly for a lithium secondary battery. The positive and negative layers of the electrode assembly  10  are formed at a side thereof with a large negative lead area  111  and a large uncoated positive lead area  112 . In addition, a large collecting area  121  is formed in the mid of the lead terminal  12  and is located correspondingly to the negative lead area  111  or the positive lead area  112 . And then a pressing piece  131  of the clasping assemblies  13  is fixed outside the positive lead area  111  or the negative lead area  112 . In this way, the two conductive pressing pieces  131  are firmly pressed against the positive lead area  111  or the negative lead area  112 . On the one hand, the respective layers of the positive lead area  111  or the negative lead area  112  are pressed closely against one another, and on the other hand, the positive lead area  111  or the negative lead area  112  is allowed to be maintained in a tight electrical contact with the collecting area  121  (as shown in  FIG. 2 ). 
     It is to be noted that the size of the respective components of the abovementioned lithium secondary battery must be controlled precisely; otherwise, the electrode assembly cannot be fitted into the battery case, if the battery case, the core or the lead terminal has an error in dimension. For example, if the battery case is too short or the core is too high, the core cannot be sealed hermetically in the battery case, or, if the electrode assembly is too short, as a result, only one end of the electrode assembly can be fixed to the battery case, and the other end of the electrode assembly will be too short to reach the battery case, so it cannot be fixed. 
     The electrical connection process of the leads of the electrode assembly is simplified. However, the size of the components of the electrode assembly must be controlled precisely, otherwise the electrode assembly cannot be assembled. 
     The present invention has arisen to mitigate and/or obviate the afore-described disadvantages. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a conductive connecting structure for a core assembly of a second lithium battery, wherein the conductive connecting structure is used as an electrical conductive connection for connecting the core assembly to the positive lead terminal or the negative lead terminal. The conductive connecting structure includes two bolts and two conductive connecting members, and each of the conductive connecting members is a flexible structure and consists of two conductive pressing pieces and a connecting portion. The conductive pressing pieces are disposed outside the positive lead area or the negative lead area, the bolt enables the conductive connecting member to be firmly pressed against and to be maintained in a close electrical contact with the positive lead area or the negative lead area, and the connecting portion is electrically connected to the positive lead terminal or the negative lead terminal of the case. By such arrangements, even if there is a dimension error in the core or the case, which can be overcome by the deformation of the conductive connecting structures, and thus the battery can be assembled successfully. 
     The secondary objective of the present invention is to provide a conductive connecting structure for a core assembly of a second lithium battery, wherein the conductive pressing pieces of the conductive connecting members are directly pressed against and maintained in a close electrical contact with the respective layers of the positive lead area or the negative lead area, and the conductive connecting members are electrically connected to the positive or negative lead terminal. Since the structure of the present invention is very simple and the electrical connection is direct, which contributes to reduction of the resistance of the battery. 
     To achieve the above objects, a conductive connecting structure for a core assembly of a secondary lithium battery in accordance with the present invention is disposed at both ends of the core and electrically connected to positive and negative terminals of a case of the secondary lithium battery, and comprises two conductive connecting members, each of which includes two conductive pressing pieces and a connecting portion. Each of the conductive pressing pieces is flexible and arc-shaped in cross section, namely concave inside and convex outside, and the concave inside of the each conductive pressing piece is a step structure formed by a thick portion and a thin portion. The two conductive pressing pieces are assembled with their concave insides facing each other, and then both ends of the connecting portion are connected to the thick portions of the conductive pressing pieces, so that the two conductive pressing pieces are connected to form an integral structure, and finally the connecting portions are electrically connected to the positive lead terminal and the negative lead terminal of the case, respectively, by such arrangements, the conductive connecting members can use the thick portions of the two conductive pressing pieces to hold the core of the core assembly while using the thin portions of the two conductive pressing pieces to hold the positive lead area or the negative lead area of the core in a clamping manner. 
     Two bolts are inserted through the conductive pressing pieces and the core to fix the conductive pressing pieces to the positive lead area or the negative lead area, thus establishing electric connection between the conductive pressing pieces and the positive lead area or the negative lead area. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross sectional view of a conventional core structure for a secondary lithium battery disclosed in U.S. application Ser. No. 11/456,119; 
         FIG. 2  is an exploded view of showing an electrical connection structure for a core assembly of a secondary lithium battery in accordance with the present invention; 
         FIG. 3  is an amplified view of showing a part of the core structure for a secondary lithium battery in accordance with the present invention; 
         FIG. 4  is a cross sectional view in accordance with the present invention of showing that the electrical connection structure for a core assembly is disposed in a circular battery case; and 
         FIG. 5  is a cross sectional view in accordance with the present invention of showing the interior of the battery case, wherein the core structure is additionally provided with conductive sleeve. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be clearer from the following description when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention. 
     Referring to  FIGS. 2-4 , an electrical connection structure for a core assembly of a secondary lithium battery in accordance with the present invention is illustrated, wherein two conductive connecting structures  40  are arranged at both ends of the core assembly  30  and are electrically connected to the positive lead terminal  21  or the negative lead terminal  22  of the case  20  of the battery. 
     The core assembly  30  includes a core  31  and an electrode assembly  32 . The electrode assembly  32  includes at least one positive layer  321 , one separating layer  322  and one negative layer  323  that are superposed one another and then wind around the core  31 . An uncoated area is formed at a side of the positive layer  321  for use as a positive lead area  331 , and the negative layer  323  is formed at another side thereof opposite the positive layer  321  with an uncoated area for use as a negative lead area  332 . The positive and negative lead areas  331 ,  332  protrude out of both sides of the core assembly  32 . 
     Each of the conductive connecting structures  40  includes a bolt  41  and a conductive connecting member  42 . The conductive connecting member  42  includes two conductive pressing pieces  420  and a connecting portion  423  formed between the conductive pressing pieces  420 , and the connecting portion  423  is a curved arc-shaped structure. It is to be noted that each of the conductive pressing pieces  420  is flexible and arc-shaped (which is concave inside and convex outside) in cross section, and the concave inside of the each conductive pressing piece  420  is a step structure formed by a thick portion  421  and thin portion  424  which are connected together. The two conductive pressing pieces  420  are assembled with their concave insides facing each other, and then the both ends of the connecting portion  423  are connected to the thick portions  421  of the conductive pressing pieces  420 , so that the two conductive pressing pieces  420  are connected to form an integral structure. The conductive pressing pieces  420  are disposed outside the positive lead area  331  or the negative lead area  332 , and the bolt  41  is inserted through the through hole  422  of the conductive pressing pieces  420  and the core  31  to fix the conductive pressing pieces  420  to the positive lead area  331  or the negative lead area  332 , thus establishing electric connection between the conductive pressing pieces  420  and the positive lead area  331  or the negative lead area  332 , and finally the connecting portions  423  are electrically connected to the positive lead terminal  21  and the negative lead terminal  22  of the case  20 , respectively. By such arrangements, the conductive connecting members  42  can use the thick portions  421  of the two conductive pressing pieces  421  to hold the core  31  of the core assembly  30  while using the thin portions  424  of the two conductive pressing pieces  421  to hold the positive lead area  331  or the negative lead area  332  of the core  31  in a clamping manner. 
     The core structure and the arrangement relation of the components thereof are mentioned above. The present invention intends to further improve the design of the core structure and to use the conductive connecting structures as an electrical conductive connection for connecting the conductive connecting structures  40  to the positive lead terminal  21  or the negative lead terminal  22  of the core  30 , and each of the conductive connecting members  42  is a flexible structure. By such arrangements, even if there is a dimension error in the core  30  or the case  20 , which can be overcome by the deformation of the conductive connecting members  42 , and thus the battery can be assembled successfully. 
     Referring to  FIGS. 2-4  again, the conductive connecting structures  40  serve as electrical conductive connection between the core assembly  30  and the positive lead terminal  21  or the negative lead terminal  22 . Since each of the conductive pressing pieces  420  of the conductive connecting member  42  of the conductive connecting structures  40  is flexible, it can be deformed or lengthened to a certain extent. Therefore, even if there is a dimension error in the core or the case  20 , which can be overcome by the deformation of the conductive connecting structures  40 , and thus the core assembly  30  and the case  20  can be assembled successfully. 
     It is to be noted that the concave inside and convex outside arc-shaped thin portion  424  enables the conductive pressing pieces  420  of the conductive connecting members  42  to be directly pressed against the respective layers of the positive lead area  331  or the negative lead area  332 , so as to establish electric connection between the conductive pressing pieces  420  and the positive lead area  331  or the negative lead area  332 , and the conductive connecting members  42  are electrically connected to the positive lead terminal  21  and the negative lead terminal  22 . Since the structure of the present invention is very simple and the electrical connection is direct, which contributes to the reduction of the resistance of the battery. 
     As shown in  FIG. 5 , either end of the core  31  can be covered with a conductive sleeve  50 , when the conductive pressing pieces  420  are pressed against the positive and negative lead areas  331 ,  332 , the conductive sleeve  50  can improve the electrical connection between the positive and negative lead areas  411 ,  431 , thus increasing the current path in the charge and discharge process of the battery, and reducing the resistance of the battery. 
     While we have shown and described various embodiments in accordance with the present invention, it is clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.