Patent Publication Number: US-2013252048-A1

Title: Battery and assembly method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2012-066062, filed Mar. 22, 2012; the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate to a battery and a manufacturing method thereof. 
     BACKGROUND 
     In recent years, rechargeable batteries have been widely used as power sources in electric cars, hybrid electric cars, power-assisted bicycles, and electric equipment. For instance, lithium ion rechargeable batteries, which are non-aqueous rechargeable batteries, have been used as a power source in electric cars because they have high output and high energy density. 
     A rechargeable battery is typically composed of an outer container made of aluminum (or similar metal) that is in the form of flat rectangular box. The battery has an electrode group housed together with an electrolytic solution in the outer container and electrode terminals, which are connected to the electrode group and set in the outer container. 
     In addition, in order to attain high capacity and high output, a rechargeable battery may consist of a plurality of cells arranged in a case or box. The plurality of cells may be connected in parallel or in a series to create a battery set. The terminals of the individual cells may be attached to bus bars or electric circuits that connect cells adjacent to the outer surface of the battery set. 
     In the battery set, the processes of assembling the plurality of cells and electrically connecting plural leads, terminals and bus bars are complicated. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing the external appearance of a rechargeable battery device according to an embodiment. 
         FIG. 2  is a perspective view showing the internal structure of the rechargeable battery device. 
         FIG. 3  is a perspective view showing the composition of electrode group of the rechargeable battery device. 
         FIG. 4  is a perspective view showing the upper side of bus bar of the rechargeable battery device. 
         FIG. 5  is a perspective view showing the bottom side of bus bar of the rechargeable battery device. 
         FIG. 6  is a cross-sectional view showing the connection structure of the rechargeable battery device. 
         FIG. 7  is a perspective view showing part of the assembling process of the rechargeable battery. 
     
    
    
     DETAILED DESCRIPTION 
     In general, according to one embodiment, a rechargeable battery device according to an embodiment will be explained by referring to  FIG. 1  to  FIG. 7 . In each figure, direction arrows X, Y, and Z show three mutually orthogonal directions. Furthermore, in each diagram, appropriate parts of the rechargeable battery is expanded, reduced or omitted for purpose of illustration. 
     A battery according to one embodiment includes a plurality of electrode members having a positive electrode plate, a negative electrode plate, and an insulating separator placed between the positive electrode plate and the negative electrode plate, a first case made of resin, in which a plurality of leads connected electrically to each of the plurality of electrode members and bus bars having a plurality of terminals to be connected electrically to each of the plural leads are integrated, and a battery case housing the plural electrode members therein. 
       FIG. 1  is a perspective view showing the external appearance of a rechargeable battery device  1  according to an embodiment, and  FIG. 2  is a perspective view showing its internal structure. The rechargeable battery device  1  shown in  FIG. 1  and  FIG. 2  is composed of a battery case  11  with a housing part  11   a  (see  FIG. 7 ) which is a space formed by dividing the inner part of the battery case  11  in plural numbers, plural electrode groups  12  housed together with a non-aqueous electrolytic solution in the battery case  11 , and a battery set that is made up of plural rechargeable battery units, each of which functions as a rechargeable battery. 
     Furthermore, in the embodiment, each of the electrode groups  12  is composed of electrode members including a positive electrode plate, a negative electrode plate, an insulating separator placed therebetween, and leads which are connected electrically to each of the positive electrode plate and the negative electrode plate (for example, positive electrode lead  22   a  and negative electrode  22   b  in  FIG. 3 ). 
     The battery case  11  has a first case  13  and a second case  14 , and has a rectangular box form. The first case  13  and the second case  14  are sealed to form a sealed space in the battery case  11 , in which a non-aqueous electrolytic solution and plural electrode groups  12  are housed. 
     As resin materials to be used in the first case  13  and the second case  14 , thermoplastic resins (non-crystalline) are preferred, for example, modified PPE (polyphenylene ether). 
     The first case  13  has a “basket” form, and many partitioning plates are placed therein. More specifically, the first case  13  is equipped with an outer part (basket body)  13   a,  which has a bottom-opened rectangular box form, and plural partitioning plates  13   b,  which are arranged in parallel within the outer part  13   a.  The outer part  13   a  has a ceiling wall  13   c , which covers one side of the electrode group  12 , and side walls  13   d,  which cover the circumference, and has an opening at the bottom side. In the ceiling wall  13   c,  plural bus bars  15  are integrated therein by insert molding. The outer part  13   a  carries out a function of preventing short-circuit between terminals by electrical insulation 
     A substrate housing part  13   e  is formed on the outer surface side of the ceiling part  13   d,  on which a circuit substrate  17  for voltage detection is arranged. The substrate housing part  13   e  has a concavity at its upper side with a fixed width along the longitudinal direction (X direction) in the central part of the battery case  11 . 
     In the substrate housing part  13   e,  voltage detection terminals  15   d  being constituted as a part of bus bar  15  and outer output terminal  16 , which is connected individually to positive electrode lead  22   a  of the electrode group  12  at one end of the array and negative electrode lead  22   b  of the electrode group  12  at the other end of the array, are exposed to the outer side of the first case  13 . 
     The partition plates  13   b  are arranged in parallel so as to partition the inner space of the outer part  13   a  a plural number of times in the X direction and to form in parallel plural housing compartments  11   a  (see  FIG. 7 ) each having a form corresponding to the shape of the electrode group  12 . In the embodiment,  11  units of partition plates  13   b  are formed in parallel along the X direction, and  12  units of housing compartment  11   a  are formed in parallel in the X direction. The partition plate  13   b  carries out a position-locating function of electrode group  12  and prevents short-circuit between the electrode groups  12 . 
     Each of the housing compartments  11   a  has a narrow and long rectangular shape corresponding to the shape of the electrode group  12  housed therein. Each electrode group  12  is housed to extend along the width direction (Y direction) of the battery case  11  so that plural electrode groups  12  are arranged in parallel along the longitudinal direction (X direction) of the battery case  11 . 
     In the ceiling wall  13   c,  plural bus bars  15  and exterior output terminals  16  are integrally molded by inserting molding. Here,  11  units of bus bars  15  are arranged in parallel at a predetermined position so as to connect serially adjacent  12  units of electrodes in the electrode groups  12 , and exterior output terminals  16  are arranged at both ends of the array. In such a manner, plural bus bars  15  and exterior output terminals  16  are formed integrally in the first case  13 . One part of plural bus bars  15  and exterior output terminals  16  is exposed to the outside of the first case  13 , and another part thereof is within the first case  13 . 
     Besides, in the ceiling wall  13   c,  gas-discharging valves or liquid-injecting holes are formed. When gas is generated inside the case by abnormal operation and the like, and the internal pressure rises above the predetermined value, gas is released through the valves. This lowers the internal pressure and prevents failure such as rupture and the like. 
     In the present embodiment, as mentioned above, each electrode group  12  is composed of electrode members each having a positive electrode plate, a negative electrode plate and an insulating separator formed therebetween, and leads for electrically connecting each positive electrode plate and negative electrode plate of the electrode member. As shown in  FIG. 3  as an example, the composition of electrode group  12  refers to the positive electrode lead  22   a  and negative electrode lead  22   b.  As shown in  FIG. 3 , the electrode group  12  is provided with coil  21  obtained by winding the positive electrode plate and the negative electrode plate and making them into a flat shape, positive electrode lead  22   a  and negative electrode lead  22   b  which are pulled out at both sides of the coil  21 . 
     The coil  21  is formed by winding spirally a positive electrode plate, a negative electrode plate, and an insulating separator placed there-between and compressing along the diameter direction to make it into a rectangular flat form. 
     The positive electrode lead  22   a  and negative electrode lead  22   b  are extended toward an upper part higher than the coil  21  to have a plate form that is bent toward the inner side. A cap  24  is formed between the positive electrode lead  22   a  and the negative electrode lead  22   b.  The cap  24  is formed from insulating resin and the like in a plate form, and it is formed by inserting it between positive electrode lead  22   a  and negative electrode lead  22   b  so that the distance between the positive electrode lead  22   a  and the negative electrode lead  22   b  is regulated to control the positions of the positive electrode lead  22   a  and the negative electrode lead  22   b.  By the control function of the cap  24 , a pair of positive electrode leads  22   a  and negative electrode lead  22   b  can be connected with high accuracy to their respective terminals,  15   a  and  15   b.    
     Positive electrode connector  23   a  and negative electrode connector  23   b  are inserted into holes  15   e  of bus bar  15  to connect the terminal  15   a  and the terminal  15   b  respectively to the positive electrode lead  22   a  and negative electrode lead  22   b.    
     Plural electrode groups  12  are arranged so as to stand alternate between positive electrode connector  23   a  and negative electrode connector  23   b  of adjoining electrode groups  12 . Plural electrode groups  12  are electrically connected serially by plural bus bars  15  as conductive material. 
     Exterior output terminals  16  are connected respectively to the negative electrode connector  23   b  of the electrode group  12  positioned at one end of the array among plural electrode groups  12  and the positive electrode connector  23   a  of the electrode groups  12  positioned at the other end of the array. 
     Each of plural bus bars  15 , shown in  FIG. 1 ,  FIG. 2 ,  FIG. 4 , and  FIG. 5 , is made from conductive materials such as metallic materials, e.g. aluminum, copper, bronze and the like, and includes the terminals  15   a,    15   b,  connection plate  15   c  for connecting them, and the voltage detection terminal  15   d  as one integrated single body. 
     Here, bus bar  15  has a T-shape, and has a pair of cylindrical terminals  15   a,    15   b  connected to each other integrally, and a part of the middle of terminals  15   a,    15   b  extended towards the central part in the width direction (arrow direction Y) to function as a voltage detection terminal  15   d.    
     The terminal  15   a  at one side is connected to positive electrode connector  23   a  of an electrode group  12  while the terminal  15   b  at the other side is connected to negative electrode connector  23   b  of an adjacent electrode group  12 , and those electrode terminals are connected electrically. Twelve units of electrode group  12  are connected serially by plural bus bars  15  in the same manner as described above. Alternatively, plural electrode groups  12  may be connected in parallel. 
     Each of the terminals  15   a,    15   b  is composed of, for example, the form of cylinder having a bottom, and a hole  15   e , which extends in the Z direction, is formed at the center of the bottom. 
     One end of terminals  15   a,    15   b  is projected to the inner side of ceiling  13   a  of the first case  13 . The terminals  15   a ,  15   b  are joined to the first case  13  by insert molding and buried therein as an integrated member. The voltage detection terminal  15   d  is exposed to the outside from the concave part  13   e  of the first case  13 . 
     Each of the terminals  15   a  and  15   b  of bus bar  15  is arranged to correspond to each of positive electrode lead  22   a  and negative electrode lead  22   b,  and each electrode group  12  is located in a corresponding housing compartment  11   a  of the first case  13 , while positive electrode connector  23   a  and negative electrode connector  23   b,  which correspond to positive electrode lead  22   a  and negative electrode lead  22   b  of electrode group  12 , respectively, are inserted into holes  15   e  of the terminals  15   a  and  15   b.    
     With the configuration described above, positive electrode connector  23   a  and negative electrode connector  23   b  of adjacent electrode groups  12  are electrically connected to each other through connector  15   c  and terminal  15   a,    15   a  of bus bar  15 . 
     Exterior output terminal  16  has a terminal  16   a  or  16   b  composed of cylindrical part with a hollow insertion part (hole) at the bottom thereof and a plate-form voltage detection terminal  16   c,  which extends from a center portion of the terminal  16   a  or  16   b,  and they are formed integrally as one body from conductive materials such as metallic materials, e.g., aluminum, copper, bronze, gold and the like. 
     The terminal  16   a  or  16   b  of the exterior output terminal  16  is arranged to correspond to negative electrode connector  23   b  of electrode group  12  positioned at one end of the array of electrode groups  12  and positive electrode connector  23   a  of electrode group  12  positioned at the other end of the array. The position of electrode group  12  is determined in housing compartment  11   a  of the first case  13  while positive electrode connector  23   a  and negative electrode connector  23   b  are inserted, respectively, into the holes of the terminal  16   a  or  16   b.    
     A circuit board  17 , which includes a voltage control unit, a voltage detection unit, and a temperature sensor or the like, is formed in the substrate housing part  13   e  that is at the outer surface side of the first case  13 , and connected electrically to the voltage detection terminal  15   b,    16   c  exposed to the outside of substrate housing part  13   e.    
     The second case  14  is provided with plate-form bottom wall  14   a  closing up the bottom opening of the first case  13 . 
     The top surface of bottom wall  14   a  is provided with curved surfaces, which are curved along the shape of electrode group  12  and arranged in parallel. After housing the electrode group  12 , the second case  14  is assembled to the first case  13  in a manner of closing up the bottom opening so that the housing compartment  11   a  is closed up. 
     Hereinafter, the method of assembling batteries according the present embodiment is explained by referring to  FIG. 6  and  FIG. 7 . In terms of the assembling process, as shown in  FIG. 6  and  FIG. 7 , first, electrode group  12  is arranged in the first case  13  by inserting individual electrode group  12  into each housing compartment  11   a  of the first case  13  through the bottom opening. 
     As described above, the first case  13  is a resin molded article and has a basket form. In the first case  13 , each of the electrode groups  12  is arranged in the compartment  11   a  of the battery case  11  so that positive electrode connector  23   a  and negative electrode connector  23   b  corresponding to positive electrode lead  22   a  and negative electrode lead  22   b  of adjacent electrode groups  12 , respectively, are inserted into respective holes  15   e  of the terminals  15   a  and  15   b  that are connected by connection part  15   c.  In the first case  13 , positive electrode connector  23   a  and negative electrode connector  23   b,  which are connected to positive electrode lead  22   a  and negative electrode lead  22   b,  respectively, are electrically connected by bus bar  15 . Furthermore, positive electrode connector  23   a  and negative electrode connector  23   b  of electrode group  12  at both ends of array are inserted into respective hole of exterior output terminals  16  and joined by electrical connection and physical joining. 
     As shown in  FIG. 7 , the second case  14  is assembled at the arranged state of all electrode groups  12  so as to close up the bottom opening of the first case  13 . Thus, electrode group  12  is housed in compartment  11   a  and sealed. 
     Then, circuit board  17  is arranged in substrate housing part  13   e  so as to connect to voltage detection terminals  15   d ,  16   c  which are exposed to the outer surface of the first case  13 . 
     Furthermore, various treatments such as electrolytic solution treatment, initial charging and discharging, and the like are carried out in order to complete the rechargeable battery device  10  as a battery set. 
     The following effect is achieved by the rechargeable battery device and the method of assembling a rechargeable battery device according to this embodiment. Namely, since bus bar  15  is integrated into the resin-made battery case  11 , the assembling process can be simplified and also the problems in the installation process of bus bar  15  can be reduced so that the loss of product yield can be reduced. 
     Electrode group  12  with coil  21 , positive electrode lead  22   a,  and negative electrode lead  22   b  is arranged in the compartment  11   a  in the battery case  11 , positive electrode connector  23   a  and negative electrode connector  23   b,  which correspond to positive electrode lead  22   a  and negative electrode lead  22   b  of the electrode group  12 , respectively, are inserted into a hole  15   e  of bus bar  15  simultaneously at the time of assembling of battery case  11 . Therefore, number of assembling parts can be reduced and assembling process can be simplified with preservation of high accuracy. 
     Furthermore, in the embodiment, a case of arranging plural electrode groups  12 , for example, in a row and connecting them electrically in series is explained, but the present invention is not limited to this. The present invention can be applied to cases where the plural electrode groups  12  are connected in parallel. Even in such cases, electrical connection of leads and bus bars can be easily carried out during the assembling of electrode groups into the case since bus bars are integrated in the resin-made case. 
     In the embodiment, partition plate  13   b  is integrated at the side of the first case  13  and plural housing compartments  11   a  are produced, but it is limited to this case only. For example, it can be composed by separating the ceiling  13   a  and the side part  13   c  and making a third case with side part  13   c  and partition plate  13   b  as a separate structure. Even such a case, bus bar  15  is insert-molded integrally in ceiling  13   a  so that same effect of the embodiment is obtained. 
     Various materials besides the modified PPE can be used as resins for the first case  13  and the second case  14 . For example, olefin resins such as PE, PP, PMP and the like, polyester resins such as PET, PBT, PEN and the like, POM resin, polyamide resins such as PA6, PA66, PA12 and the like, crystalline resins such as PPS resin, LCP resin and the like, and their alloy resins, non-crystalline resins such as PS, PC, PC/ABS, ABS, AS, PES, PEI, PSF and the like, and their alloy resin can be used. In addition, positive electrode material and negative electrode material of coil  21 , and materials for terminal  15  can be modified according to the aforementioned materials. 
     While certain embodiments have been described, these embodiments have been presented as examples only, and are not intended to limit the scope of the inventions. In fact, the novel embodiments described herein maybe embodied in a variety of other forms; furthermore, various omissions, substitutions and changes of the embodiments described herein can be made without departing from the spirit of the inventions. The claims described below and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.