Patent Publication Number: US-2023147539-A1

Title: Cylindrical Battery and Method for Manufacturing the Same

Description:
TECHNICAL FIELD 
     Cross Citation with Related Application(s) 
     This application claims the benefit of Korean Patent Application No. 10-2019-0127310 filed on Oct. 14, 2019 with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     The present disclosure relates to a cylindrical battery and a method for manufacturing the same. 
     BACKGROUND ART 
     As energy prices are increasing due to the depletion of fossil fuels and increasing attention is being paid to environmental pollution, the demand for environmentally-friendly alternative energy sources acts as an essential factor for future life. Thus, research into techniques for generating various kinds of power, such as nuclear energy, solar energy, wind energy, and tidal power, is underway, and power storage apparatuses for more efficient use of the generated energy are also drawing great attention. 
     Moreover, the demand for batteries as energy sources is rapidly increasing as mobile device technology continues to develop and the demand for such mobile devices continues to increase. Accordingly, much research on batteries capable of satisfying various needs has been carried out. In particular, in terms of the material for batteries, the demand for lithium secondary batteries, such as lithium ion batteries and lithium ion polymer batteries, which have advantages such as high energy density, discharge voltage, and output stability, is very high. 
     The secondary battery may be classified based on the structure of an electrode assembly having a structure in which a positive electrode and a negative electrode are stacked with a separator being interposed between therebetween. For example, the electrode assembly may include a jelly-roll (wound) type electrode assembly in which a long sheet type positive electrode and a long sheet type negative electrode are wound with a separator being interposed therebetween, a stacked (laminated) type electrode assembly in which pluralities of positive electrodes and negative electrodes cut to a predetermined size are sequentially stacked with separators being interposed therebetween, and the like. In recent years, in order to solve problems caused by the jelly-roll type electrode assembly and the stacked type electrode assembly, there has been developed a stacked/folded type electrode assembly, which is a combination of the jelly-roll type electrode assembly and the stacked type electrode assembly, having an improved structure in which predetermined numbers of positive electrodes and negative electrodes are sequentially stacked with separators being interposed therebetween to constitute a unit cell, after which a plurality of unit cells is sequentially wound in the state of having been placed on a separation film. 
     These electrode assemblies are housed in a pouch case, a cylindrical can, a prismatic case, and the like depending on the purpose of use, thereby producing a battery. 
     Among them, the cylindrical battery has the advantages of being easy to manufacture and having a high energy density per weight, and thus, is used as an energy source for various devices ranging from portable computers to electric vehicles. 
       FIG.  1    is a schematic diagram illustrating a conventional cylindrical battery. 
     Referring to  FIG.  1   , the cylindrical battery  10  is manufactured by housing a jelly-roll type electrode assembly  12  in a cylindrical case  13 , injecting an electrolyte solution in the cylindrical case  13 , and coupling a top cap  14  to an opened upper end of the cylindrical case  13 . The jelly-roll type electrode assembly  12  has a structure, in which a positive electrode  12   a,  a separator  12   b  and a negative electrode  12   c  are sequentially stacked to be wound in a round shape. A cylindrical center pin  15  is inserted into a central part of the electrode assembly  12 . The center pin  15  functions to fix and support the electrode assembly  12 , and also functions as a passage for discharging a gas generated through internal reactions during charging/discharging and operation. 
     Since the cylindrical case  13  of such a conventional cylindrical battery  10  has a single-layer structure made of a metal material, heat is easily discharged to the outside. Therefore, when the cylindrical battery  10  is used in a low-temperature environment, an internal heat generated in a charge and discharge process is easily discharged to the outside, which causes a problem that the performance of the battery is rapidly reduced. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Technical Problem 
     It is an object of the present disclosure to provide a cylindrical battery provided with a battery case having excellent heat insulating properties. 
     However, the problem to be solved by the embodiment of the present disclosure is not limited to the above-mentioned problem, and can be variously expanded within the scope of the technical idea included in the present disclosure. 
     Technical Solution 
     A cylindrical batter according to one embodiment of the present disclosure includes: an electrode assembly; and a battery case which houses the electrode assembly and is formed of a resin. 
     The battery case may include an upper case, a side case and a lower case, and a hollow may be formed in the side case. 
     The side case may include an inner case and an outer case. 
     The hollow may be formed between the inner case and the outer case. 
     The lower case may include a terminal connection part. 
     A stepwise-type step may be formed on the side surface of the terminal connection part. 
     The lower case may include a mounting space corresponding to the shape of the terminal connection part. 
     The terminal connection part may be made of a metal material. 
     A negative electrode tab of the electrode assembly may be electrically connected to the terminal connection part. 
     The upper case may include a first coupling part. 
     The side case may include a second coupling part. 
     The first coupling part may be a latch. 
     The second coupling part may include a groove to which the latch is fastened. 
     The first coupling part may include a screw thread or a screw valley. 
     The second coupling part may include a screw thread or a screw valley that is coupled to the screw thread or the screw valley. 
     A method for manufacturing the cylindrical battery may include the steps of: manufacturing an upper case; connecting the upper case to a side case, and connecting a terminal connection part to a lower case. 
     The upper case may be fastened to the side case in snap-fit manner. 
     The upper case may be coupled to the side case by a screw thread/screw valley coupling method. 
     The upper case may be manufactured by injection molding. 
     The terminal connection part moves in a direction in which gravity acts in the housing part of the battery case to be mounted in a mounting space in the lower case. 
     Advantageous Effects 
     As described above, the cylindrical battery according to the embodiment of the present disclosure can exhibit excellent heat insulating properties by including a battery case formed of a resin and having a hollow formed therein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic view showing a conventional cylindrical battery. 
         FIG.  2    is a schematic view showing a cylindrical battery according to an embodiment of the present disclosure. 
         FIG.  3    is a schematic diagram showing that the terminal connection part of  FIG.  2    is coupled. 
         FIG.  4    is a schematic view showing a cylindrical battery according to another embodiment of the present disclosure. 
         FIG.  5    is a schematic view showing that the upper case of  FIG.  4    is separated. 
         FIG.  6    is a schematic view showing a cylindrical battery according to yet another embodiment of the present disclosure. 
         FIG.  7    is a schematic view showing that the upper case of  FIG.  6    is separated. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. The present disclosure may be modified in various different ways, and is not limited to the embodiments set forth herein. 
     Further, throughout the specification, when a portion is referred to as “comprising” or “including” a certain component, it means that the portion can further include other components, without excluding the other components, unless otherwise stated. 
     Further, throughout the specification, the “hollow” means an empty space in a vacuum state. 
       FIG.  2    is a vertical cross-sectional view showing a cylindrical battery according to an embodiment of the present disclosure.  FIG.  3    is a schematic diagram showing that the terminal connection part of  FIG.  2    is coupled. 
     Referring to  FIGS.  2  and  3   , the cylindrical battery  100  may include a top cap (not shown), a battery case  110 , a terminal connection part  120 , and an electrode assembly  140 . The electrode assembly  140  may be housed inside the battery case  110 . For convenience of description, a part of the electrode assembly  140  is not shown in the figure. 
     The top cap may be mounted on the top of the electrode assembly  140 . The top cap may have a structure including a safety vent (not shown) and an electric power interrupting device (not shown). Further, the top cap may have a structure that does not include the safety vent and the electric power interrupting device. 
     The battery case  110  may include an upper case  111  , a side case  112  , and a lower case  113  . The side case  112  may include an inner case  112   a  and an outer case  112   b.    
     The battery case  120  may be formed of a resin. The resin is not particularly limited, but for example, it may be Teflon. Since the battery case  120  formed of a resin has lower thermal conductivity than a metal can, heat generated in the charging/discharging process of the cylindrical battery  100  may be maintained in the cylindrical battery  100  for a longer period of time. 
     The upper case  111  may have a shape in which the beading process has already been completed. Because such shape can be manufactured by injection molding, the manufacturing process of the cylindrical battery  100  may be simplified. The upper case  111  may be formed as a single layer. Further, the upper case may have a structure connected to the inner case  112   a  and the outer case  112   b.    
     The inner case  112   a  is located on the housing part  130  side in which the electrode assembly is housed, and the outer case  112   b  may have a structure exposed to the outside in a form surrounding the inner case  112   a.  The inner case  112   a  and the outer case  112   b  may have a cylindrical shape, and the diameter of the inner case  112   a  may be formed smaller than the diameter of the outer case  112   b . A space S spaced apart by a predetermined distance may be formed between the inner case  112   a  and the outer case  112   b.  The space S may be hollow. The space S maintained in a vacuum state has a lower thermal conductivity than the metal can structure formed as a single layer, so that an excellent heat insulating effect can be exhibited. Therefore, heat generated in the charging/discharging process of the cylindrical battery  100  may be maintained in the inside of the cylindrical battery  100  for a long period of time. 
     The lower case  113  may have a structure connected to the inner case  112   a  and the outer case  112   b.  The inner case  112   a  and the outer case  112   b  may be formed on the edge part of the lower case  113 . The lower case  113  may be formed as a single layer. Further, a terminal connection part  120  may be formed in the central part of the lower case  113 . In addition, the lower case  113  may have a structure in which a mounting space  121  corresponding to the shape of the terminal connection part  120  is formed. 
     The terminal connection part  120  may formed of a metal material. A negative electrode tab of the electrode assembly  140  may be electrically connected to the terminal connection part  120 . Therefore, the terminal connection part  120  may be a negative electrode terminal of the cylindrical battery  100 . 
     The terminal connection part  120  may have a shape in which two or more low-height cylinders are stacked. Because the cylinders have different cross-sectional diameters, the side surface of the terminal connection part  120  may have a structure in which a stepwise-type step is formed. In one example, the terminal connection part  120  may have a structure in which a cylinder C 1  having a large cross-sectional diameter is stacked on a cylinder C 2  having a small cross-sectional diameter. 
     Therefore, the terminal connection part  120  may move in a direction in which gravity acts in the housing part  130  to be mounted in the mounting space  121 . 
     The terminal connection part  120  and the mounting space  121  may be coupled through various connection structures. In one example, a connection part between the terminal connection part  120  and the mounting space  121  may be coupled to each other by forming a screw thread and a screw valley. Further, rubber O-rings may be included at a connection part between the terminal connection part  120  and the mounting space  121 . Through the above coupling, it is possible to prevent the electrolyte solution from leaking to the outside. 
       FIG.  4    is a schematic view showing a cylindrical battery according to another embodiment of the present disclosure. 
       FIG.  5    is a schematic view showing that the upper case of  FIG.  4    is separated. 
     Referring to  FIGS.  4  and  5   , the cylindrical battery  200  may include a top cap (not shown), a battery case  210 , a terminal connection part  220  , and an electrode assembly (not shown). The battery case  210  may include an upper case  211 , a side case  212  , and a lower case  213 . 
     The upper case  211  may include a first coupling part  211   a.  The upper case  211  may be coupled to the side case  212  via the first coupling part  211   a.  The first coupling part  211   a  may be a latch. 
     The side case  212  may include an inner case  212   a,  an outer case  212   b,  and a second coupling part  212   c.  The side case  212  may be coupled to the upper case  211  via the second coupling part  212   c . The second coupling part  212   c  may include a groove structure capable of coupling with the latch. 
     According to such a structure, the upper case  211  and the side case  212  may be fastened in snap-fit manner. This has the effect of simplifying the manufacturing process of the cylindrical battery  100 . 
       FIG.  6    is a schematic view showing a cylindrical battery according to yet another embodiment of the present disclosure.  FIG.  7    is a schematic view showing that the upper case of  FIG.  6    is separated. 
     Referring to  FIGS.  6  and  7   , the cylindrical battery  300  may include a top cap (not shown), a battery case  310 , a terminal connection part  320  , and an electrode assembly (not shown). The battery case  310  may include an upper case  311 , a side case  312 , and a lower case  313 . The side case  312  may include an inner case  312   a  and an outer case  312   b.    
     The upper case  311  may include a first coupling part  311   a.  The upper case  311  may be coupled to the side case  312  via the first coupling part  311   a.  The first coupling portion  311   a  may include a screw thread or a screw valley. 
     The side case  312  may include an inner case  312   a,  an outer case  312   b,  and a second coupling part  312   c.  The side case  312  may be coupled to the upper case  311  via the second coupling part  312   c . The second coupling portion  312   c  may include a screw thread or a screw valley. 
     According to such as structure, the upper case  311  can be rotated and coupled to the side case  312 . This has the effect of simplifying the manufacturing process of the cylindrical battery  300 . In addition, the upper case  311  can be easily separated from the side case  312  if necessary. 
     It will be appreciated by those skilled in the art that various applications and modifications can be made without departing the sprit and scope of the invention based on the above description.