Patent Publication Number: US-2022223971-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. 10-2019-0086460, filed on Jul. 17, 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 much 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. 
     Secondary batteries 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 in the state in which a separator is interposed between the positive electrode and the negative electrode. For example, the electrode assembly may be configured to have a jelly-roll (wound) type structure in which a long sheet type positive electrode and a long sheet type negative electrode are wound in the state in which a separator is disposed between the positive electrode and the negative electrode or a stacked (laminated) type structure in which pluralities of positive electrodes and negative electrodes each having a predetermined size are sequentially stacked in the state in which separators are disposed respectively between the positive electrodes and the negative electrodes. 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 in the state in which separators are disposed respectively between the positive electrodes and the negative electrodes to constitute a unit cell, after which a plurality of unit cells is sequentially folded in the state of having been placed on a separation film. 
     These electrode assemblies are mounted in a pouch case, a cylindrical can, a prismatic case, and the like depending on the purpose of use to produce 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 cross-sectional schematic diagram illustrating a cylindrical battery according to the related art. 
     Referring to  FIG. 1 , the cylindrical battery  100  is manufactured by receiving a jelly-roll type electrode assembly  120  in a cylindrical case  130 , injecting an electrolyte in the cylindrical case  130 , and coupling a top cap  140  to an opened upper end of the cylindrical case  130 . 
     The jelly-roll type electrode assembly  120  has a structure, in which a positive electrode  121 , a negative electrode  122 , and a separator  123  are stacked to be wound in a round shape, and a cylindrical center pin  150  is inserted into a central portion of the electrode assembly  120 , which is a winding core. The center pin  150  functions to fix and support the electrode assembly  120 , and also functions as a passage for discharging gas generated through internal reactions when the battery is charged and discharged, and is operated. 
     An oxidation and a decomposition reaction of the electrolyte are performed as the conventional cylindrical battery  100  is repeatedly charged and discharged, so that there is a problem that the lifetime of the cylindrical battery  100  rapidly decreases. However, according to the conventional cylindrical battery  100 , the electrolyte can be neither exchange nor added structurally. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Technical Problem 
     It is an object of the present disclosure to provide a cylindrical battery which can extend the lifetime of the cylindrical battery by adding an electrolyte, and a method for manufacturing the same. 
     However, the problem to be solved by the embodiments of the present disclosure is not limited to the above-described problems, and can be variously expanded within the scope of the technical idea included in the present disclosure. 
     Technical Solution 
     A cylindrical battery according to an embodiment of the present disclosure includes a metal can, an electrode assembly mounted in the metal can, a cap assembly located at an upper end of the metal can, the cap assembly including a top cap, a safety vent, and a current cut-off member. A hole mark may be formed on the safety vent. 
     The top cap may include an exhaust hole. 
     An opening may be formed in the current cut-off member. 
     The exhaust hole, the hole mark, and the opening may be located along an imaginary straight that is perpendicular to a bottom of the metal can. 
     The top cap may make contact with the safety vent along a periphery of the safety vent. 
     The hole mark may be formed on the periphery of the safety vent. 
     The hole mark may be applied with a dye that is visible by naked eyes through the exhaust hole. 
     The dye may be a fluorescent dye. 
     The top cap may include two or more exhaust holes. 
     The hole mark may be provided as two or more hole marks corresponding to the exhaust holes. 
     A notch may be formed at the hole mark. 
     The dye may be applied to the notch. 
     A method for manufacturing a cylindrical battery by adding an electrolyte to the cylindrical battery may include the steps of forming a through-hole in the hole mark, inserting an electrolyte injection tube into the through-hole, injecting an electrolyte through the electrolyte injection tube, removing the electrolyte injection tube, and sealing the through-hole. 
     The electrolyte injection pipe may pass through the hole mark while being inclined at a predetermined angle toward the outside of the cylindrical battery with respect to an imaginary straight line that is perpendicular to a bottom of the metal can. 
     The predetermined angle may be fifty degrees or less. 
     The step of sealing the through-hole may include a step of sealing the through-hole through laser welding. 
     The step of sealing the through-hole may include a step of sealing the through-hole with silicone. 
     Advantageous Effects 
     As described above, the cylindrical battery and the method for manufacturing the same according to the embodiments of the present disclosure can additionally inject the electrolyte, thereby prolonging the lifetime of the cylindrical battery. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional schematic diagram illustrating a cylindrical battery according to the related art; 
         FIG. 2  is a cross-sectional schematic diagram illustrating a cylindrical battery according to an embodiment of the present disclosure; 
         FIG. 3  is a schematic diagram illustrating a safety vent of  FIG. 2 ; 
         FIGS. 4 and 5  are schematic diagrams illustrating a state in which an electrolyte injection tube of  FIG. 2  passes through a cap assembly; 
         FIG. 6  is a cross-sectional schematic diagram illustrating a cylindrical battery according to an embodiment of the present disclosure; 
         FIG. 7  is a schematic diagram illustrating a cap assembly of  FIG. 6 ; 
         FIG. 8  is a cross-sectional schematic diagram illustrating a cylindrical battery according to another embodiment of the present disclosure; 
         FIG. 9  is a cross-sectional schematic diagram illustrating a cylindrical battery according to another embodiment of the present disclosure; and 
         FIG. 10  is a flow diagram of a method for manufacturing a cylindrical battery. 
     
    
    
     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 part is referred to as “including” a certain component, it means that it can further include other components, without excluding the other components, unless otherwise stated. 
       FIG. 2  is a cross-sectional schematic diagram illustrating a cylindrical battery according to an embodiment of the present disclosure. 
     Referring to  FIG. 2 , the cylindrical battery  200  can be configured so that a jelly-roll type electrode assembly  240  inserts into the interior of a metal can  230 , and a cap assembly  210  mounts on an opened upper end of the metal can  230 . The cap assembly  210  may include a top cap  211 , a safety vent  212 , a current shut-off member  213 , and a gasket  215 . 
     The top cap  211  may have a structure in which a positive electrode terminal is formed to protrude to the outside of the cylindrical battery  200  and an exhaust hole  214  is punched. The top cap  211  may be electrically connected to the safety vent  212  along a periphery of the safety vent  212 . 
     The safety vent  212  may have a predetermined notch  222  formed therein so as to be burst by a high-pressure gas of the cylindrical battery  200 . The safety vent  212  maintains a downward protruding structure when the cylindrical battery  200  is normally operated. However, when gas is generated in the interior of the cylindrical battery  200  and the internal pressure of the gas increases, the safety vent  212  may protrude upwards to be burst and thus the internal gas may be discharged. 
     The current shut-off member  213  may interrupt current to relieve internal pressure when the cylindrical battery  200  abnormally operates. The current shut-off member  213  may be mounted on a space between the electrode assembly  240  and the safety vent  212 . An opening  217 , through which an electrolyte injection tube  50  passes, may be formed in the current shut-off member  213 . 
     The gasket  215  may be mounted on an outer peripheral surface of the top cap  211  to electrically insulate the top cap  211  acting as the positive electrode terminal and the metal can  230  acting as a negative electrode terminal. 
       FIG. 3  is a schematic diagram illustrating a safety vent of  FIG. 2 . 
     Referring to  FIGS. 2 and 3 , a hole mark  216 , through which the electrolyte injection tube  50  may pass, may be marked on the safety vent  212 . The location of the hole mark  216  is not particularly limited, but may be formed at a periphery of the safety vent  212 , which makes contact with the top cap  211 . In order to form a through-hole, through which the electrolyte injection tube  50  passes in the hole mark  216 , a predetermined pressure may be applied to the electrolyte injection tube  50  to form the through-hole. Here, it is not preferable that a structure of the safety vent  212  is deformed by the pressure. Accordingly, it is preferable that the hole mark  216  is formed at the peripheral portion of the safety vent  212 , which makes contact with the top cap  211 , such that the safety vent  212  is not deformed by the pressure. 
       FIGS. 4 and 5  are schematic diagrams illustrating a state in which an electrolyte injection tube of  FIG. 2  passes through a cap assembly. 
     Referring to  FIG. 4 , the electrolyte injection tube  50  shaped like an injection needle may pass through the exhaust hole  214  and then pass through the hole mark  216  and the opening  217 . The exhaust hole  214 , the hole mark  216 , and the opening  217  may be located in a row on an imaginary straight line (a dotted line arrow of  FIG. 4 ) that is perpendicular to a ground surface and faces an opposite direction to the gravity. Through the structure, the electrolyte injection tube  50  may pass through the cap assembly  210  in a direction that is perpendicular to the ground surface and is opposite to the gravity. 
     Referring to  FIG. 5 , the electrolyte injection tube  50  may be inserted while being inclined by a predetermined angle ( 0 ) toward the outside of the cylindrical battery  200  with respect to the imaginary straight line (the dotted line arrow of  FIG. 4 ) that is perpendicular to the ground surface and faces an opposite direction to the gravity. If the electrolyte injection tube  50  has a structure that passes through the exhaust hole  214 , the hole mark  216 , and the opening  217 , the present disclosure is not particularly limited, but the angle (θ) may be fifty degrees or less. When the angle (θ) exceeds fifty degrees, it is not preferable because the electrolyte injection tube  50  may deform the structure of the safety vent  212 . However, the angle (θ) may exceed fifty degrees depending on the structure of the safety vent  212 . 
     When the through-hole, through which the electrolyte injection tube  50  passes, is formed in the hole mark  216 , the through-hole may be formed by pressing the electrolyte injection tube  50 , and the through-hole may be also formed by using a separate device. 
     The gasket  215  may be mounted so as to surround the periphery of the top cap  211  to electrically insulate the top cap  211  acting as the positive electrode terminal and the metal can  230  acting as the negative electrode terminal. 
       FIG. 6  is a cross-sectional schematic diagram illustrating a cylindrical battery according to another embodiment of the present disclosure.  FIG. 7  is a schematic diagram illustrating a cap assembly  310  of  FIG. 6 . 
     Referring to  FIGS. 6 and 7 , the cylindrical battery  300  may include a cap assembly  310  including a safety vent  312 , in which a hole mark  316  is formed. The hole mark  316  may be applied with a dye that is visible by naked eyes. For example, the hole mark  316  may be applied with a fluorescent dye. 
     Further, the dye applied to the hole mark  316  may have a water resistance, by which the dye is prevented from being removed due to moisture generated in the interior of the cylindrical battery  300 . Further, the dye applied to the hole mark  316  may have a heat resistance, by which the dye is prevented from being influenced due to heat generated in the interior of the cylindrical battery  300 . 
     Due to the structure, an operator may recognize the location of the hole mark  316  by naked eyes through an exhaust hole  314 . 
     The cylindrical battery  300  is the same structure as the cylindrical battery  200  illustrated in  FIG. 2  except for the above-described structure, and thus a detailed description thereof will be omitted. 
       FIG. 8  is a cross-sectional schematic diagram illustrating a cylindrical battery according to another embodiment of the present disclosure. 
     Referring to  FIG. 8 , the cylindrical battery  400  may have a structure including two or more electrolyte injecting paths. The cylindrical battery  400  may include a safety vent  412 , in which two or more hole marks  416  are formed. In correspondence to the locations of two or more hole marks  416 , a top cap  411  may include two or more exhaust holes  414 . Further, in correspondence to the locations of two or more hole marks  416 , a current shut-off member  413  may include two or more openings  417 . 
     Through the structure, the cylindrical battery  400  may include two or more paths, through which the electrolyte injection tube  50  may pass, and an operator may uniformly disperse an electrolyte to an electrode assembly  440 . 
     The cylindrical battery  400  is the same structure as the cylindrical battery  200  illustrated in  FIG. 2  except the above-described structure, and thus a detailed description thereof will be omitted. 
       FIG. 9  is a cross-sectional schematic diagram illustrating a cylindrical battery according to another embodiment of the present disclosure. A illustrates an enlarged notch formed in a hole mark. 
     Referring to  FIG. 9 , the cylindrical battery  500  may include a safety vent  512 , in which a hole mark  516  is formed. The hole mark  516  may include a notch  526 . The shape of the notch  526  is not particularly limited, but may be a structure having a rectangular cross-section as an example. A portion of the hole mark  516 , at which the notch  526  is formed, may have a thin thickness as compared with the other portions of the safety vent  512 . 
     A dye that is visible by naked eyes may be applied to the portion of the safety vent  512 , at which the notch  526  is formed. 
     Due to the structure, an electrolyte injection tube  50  may pass through the hole mark  516  even with a relatively small pressure. 
     In the cylindrical batteries  200 ,  300 ,  400 , and  500  according to the present disclosure, an electrolyte corresponding to 10% to 20% of the injected electrolyte may be added through the hole marks  216 ,  316 ,  416 , and  516  when the cylindrical batteries are manufactured. 
     If the electrolyte is completely added, the through-holes formed in the hole marks  216 ,  316 ,  416 , and  516  can be sealed through laser welding or with silicone. Through the addition of electrolytes, it can be identified that lifetimes of the cylindrical batteries  200 ,  300 ,  400 , and  500  are prolonged by 30% to 35%. The added electrolytes can be manufactured while a specific component is added and/or removed according to the deterioration of the batteries. 
       FIG. 10  is a flow diagram of a method for manufacturing a cylindrical battery. 
     The method for manufacturing one of the cylindrical battery by adding an electrolyte to the cylindrical battery generally includes forming a through-hole in the hole mark (S 1 ), inserting an electrolyte injection tube into the through-hole (S 2 ), injecting an electrolyte through the electrolyte injection tube (S 3 ), removing the electrolyte injection tube (S 4 ), and sealing the through-hole (S 5 ). 
     Based on the above disclosure, this is to be understood by those of ordinary skill in the art that various applications and modifications can be made within the scope of the present disclosure.