Patent Publication Number: US-2023138783-A1

Title: Button-type secondary battery

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims the benefit of the priority of Korean Patent Application Nos. 10-2020-0120950, filed on Sep. 18, 2020, and 10-2021-0123505, filed on Sep. 15, 2021, which are hereby incorporated by reference in their entirety. 
     TECHNICAL FIELD 
     The present invention relates to a button-type secondary battery, and more particularly, to a button-type secondary battery, in which an electrode tab provided in an electrode assembly is capable of selectively extending in length. 
     BACKGROUND ART 
     In general, secondary batteries refer to chargeable and dischargeable, unlike primary batteries that are not chargeable. The secondary batteries are being widely used for mobile phones, notebook computers, and camcorders, electric vehicles, and the like. 
     The secondary battery comprises a button-type secondary battery having a high energy density, a high output, and a long lifespan. The button-type secondary battery comprises an electrode assembly, a lower can having an accommodation groove accommodating the electrode assembly, an upper can coupled to the lower can to finish the accommodation groove, and a gasket sealing a gap between the lower can and the upper can. 
     Also, the electrode assembly has a structure in which a first electrode and a second electrode are sequentially stacked with a separator therebetween. Here, the first electrode is provided with a first electrode tab connected to the lower can, and the second electrode is provided with a second electrode tab connected to the upper can. 
     Here, one end of the second electrode tab is coupled to a distal end of the second electrode disposed on an outer surface of the electrode assembly, and the other end of the second electrode tab is coupled to a bottom surface of the upper can. 
     However, the second electrode tab has be secured as long as a set length to connect the second electrode of the electrode assembly to the upper can. In this case, there is a problem in that the second electrode is bent or folded by a weight of the second electrode tab, which is secured in length. 
     DISCLOSURE OF THE INVENTION 
     Technical Problem 
     The present invention is invented to solve the above problems, and an object of the present invention is to provide a button-type secondary battery, in which an electrode tab is improved to be capable of selectively extending in length so as to prevent the electrode assembly from being deformed, and the electrode tab is sufficiently secured in length to stably connect the electrode assembly to an upper can. 
     Technical Solution 
     A button-type secondary battery according the present invention for achieving the above object comprises: an electrode assembly; a lower can configured to accommodate the electrode assembly; an upper can coupled to an opening of the lower can; a gasket configured to insulate the lower can and the upper can from each other; a first tab part configured to connect a first electrode of the electrode assembly to the lower can; and a second tab part configured to connect a second electrode of the electrode assembly to the upper can, wherein the second tab part comprises a second electrode tab and a second lead tab, and the second electrode tab is connected to the second electrode, and the second lead tab connects the second electrode tab to the upper can. 
     The second electrode tab may have a length less than that of the second lead tab. 
     The second electrode tab may have a thickness less than that of the second lead tab. 
     The second electrode tab and the second lead tab may be coupled to each other through welding in a state in which ends of the second electrode tab and the second lead tab, which correspond to each other, are disposed to partially overlap each other. 
     The overlapping portion of the second electrode tab and the second lead tab may have a length of 1.5 mm to 10.0 mm. 
     A protection member having insulation may be attached to the coupled portion of the second electrode tab and the second lead tab. 
     The second electrode tab may comprise a rear end coupled to the second electrode of the electrode assembly, a front end coupled to the second lead tab, and a withdrawal end disposed between the rear end and the front end and disposed on a surface of the electrode assembly, which corresponds to the upper can, and a length from the withdrawal end to the front end of the second electrode tab may be equal to or less than a width of the second electrode tab or the second lead tab. 
     The second electrode tab and the second lead tab may be made of materials different from each other. 
     The second electrode tab may be made of a metal material that is lighter than the second lead tab. 
     The second lead tab may be made of a metal material having flexibility. 
     The first tab part may comprise a first electrode tab and a first lead tab, and the first electrode tab may be connected to the first electrode, and the first lead tab may connect the first electrode tab to the lower can. 
     The first electrode tab may have a length less than that of the first lead tab. 
     Advantageous Effects 
     The button-type secondary battery according to the present invention may comprise the electrode assembly, the lower can, the upper can, the gasket, the first tab part, and the second tab part. The second tab part may comprise the second electrode tab and the second lead tab, the second electrode tab may be connected to the second electrode of the electrode assembly, and the second lead tab may connect the second electrode tab to the upper can. Due to this characteristic, when the electrode assembly is manufactured, since only the second electrode tab of the second tab part is connected to the second electrode, the second tab part may be minimized in weight to prevent the second electrode or the electrode assembly from being deformed by the second tab part. In addition, when the electrode assembly and the upper can are coupled to each other, the length of the second tab part may be sufficiently secured by bonding the second lead tab to the second electrode tab, thereby stably connecting the electrode assembly to the upper can. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an exploded perspective view of a button-type secondary battery according to a first embodiment of the present invention. 
         FIG.  2    is a cross-sectional view illustrating a state in which an upper can is opened in the button-type secondary battery according to the first embodiment of the present invention. 
         FIG.  3    is a cross-sectional view illustrating a state in which the upper can is coupled in the button-type secondary battery according to the first embodiment of the present invention. 
         FIG.  4    is a side view illustrating another example of a second tab part provided in the button-type secondary battery according to an embodiment of the present invention. 
         FIG.  5    is a side view illustrating further another example of the second tab part provided in the button-type secondary battery according to an embodiment of the present invention. 
         FIG.  6    is an enlarged view illustrating a portion of  FIG.  3   . 
         FIG.  7    is a cross-sectional view of a button-type secondary battery according to a second embodiment of the present invention. 
         FIG.  8    is a cross-sectional view of a button-type secondary battery according to a third embodiment of the present invention. 
         FIG.  9    is a side view of a button-type secondary battery according to a fourth embodiment of the present invention. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings in such a manner that the technical idea of the present invention may easily be carried out by a person with ordinary skill in the art to which the invention pertains. The present invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, anything unnecessary for describing the present invention will be omitted for clarity, and also like reference numerals in the drawings denote like elements. 
     [Button-Type Secondary Battery According to First Embodiment of the Present Invention] 
     As illustrated in  FIGS.  1  to  6   , a button-type secondary battery  100  according to a first embodiment of the present invention is a secondary battery having a diameter greater than a length thereof and comprises an electrode assembly  110 , a lower can  120  accommodating the electrode assembly  110 , an upper can  130  coupled to an opening of the lower can  120 , a gasket  140  sealing a gap between the lower can  120  and the upper can  130  and insulating the lower can  120  from the upper can  130 , a first tab part  150  connecting a first electrode  111  of the electrode assembly  110  to the lower can  120 , and a second tab part  160  connecting a second electrode  112  of the electrode assembly to the upper can  130 . 
     The electrode assembly  110  has a structure in which the first electrode  111  and the second electrode  112  are alternately disposed with a separator therebetween and is wound in a shape of a jelly-roll. 
     Here, a distal end of the first electrode  111  and a distal end of the second electrode  112  are disposed on the outermost sides of the electrode assembly  110 , respectively. The first tab part  150  is coupled to a distal end of the first electrode  111 , and a second tab part  160  is coupled to a distal end of the second electrode  112 . 
     The first electrode is a negative electrode, and the second electrode is a positive electrode and vice versa. 
     An accommodation groove  121  accommodating the electrode assembly  110  is formed in the lower can  120 , and the first tab part  150  is coupled to a bottom surface of the accommodation groove  121 . 
     The upper can  130  is coupled to a top surface of the lower can to finish the accommodation groove  121 . 
     The gasket  140  is configured to seal the gap between the lower can and the upper can and insulate the lower can and the upper can from each other and comprises an outer gasket  141  provided between an outer circumferential surface of the lower can  120  and an inner circumferential surface of the upper can  130 , an inner gasket  142  that is in close contact with an inner circumferential surface of the lower can  120 , and a connection gasket  143  connecting the outer gasket  141  to the inner gasket  142 . 
     The first tab part  150  is configured to connect the first electrode provided in the electrode assembly to the lower can and has one end coupled to a distal end of the first electrode  111  provided in the electrode assembly  110  and the other end coupled to a bottom surface of the lower can  120 . 
     The second tab part  160  is configured to connect the second electrode provided in the electrode assembly to the upper can and has one end coupled to a distal end of the second electrode  112  provided in the electrode assembly  110  and the other end coupled to the upper can  130 . 
     The distal end of the second electrode  112  may be deformed while being bent or folded due to a weight of the second tab  160 . 
     Thus, the second tab part  160  of the button-type secondary battery  100  according to the first embodiment of the present invention has a structure that is capable of selectively extending in length. That is, since the second tab part  160  comprises a second electrode tab and a second lead tab to prevent the second electrode  112  from being deformed and improve coupling properties between the electrode assembly  110  and the upper can  130 . 
     That is, the second tab part  160  has a structure in which the second electrode tab is coupled to the distal end of the second electrode  112  of the electrode assembly  110 , and then, the second lead tab is bonded to the second electrode tab. Thus, the second tab part may selectively extend in length. 
     For example, the second tab part  160  has a structure comprising a second electrode tab  161  and a second lead tab  162 . Here, the second electrode tab  161  is connected to the distal end of the second electrode  112  of the electrode assembly  110 , and the second lead tab  162  connects the second electrode tab  161  to the upper can  130 . In addition, the second electrode tab  161  and the second lead tab  162  may be bonded to each other so that the second tab part extends in length. 
     That is, the second electrode tab  161  may be connected only to the second electrode  112  of the electrode assembly  110  to significantly reduce the self-weight of the second tab part  160 , thereby preventing the electrode assembly from being deformed. Also, when the electrode assembly and the upper can are connected to each other, the second lead tab  162  may be bonded to the second electrode tab  161 , and then, a front end of the second electrode lead may be connected to the upper can to sufficiently secure the length of the second tab part, thereby stably connecting the electrode assembly to the upper can. 
     In more detail, the second tab  160  may connect only the second electrode tab  161  to the distal end of the second electrode  112  of the electrode assembly  110  to minimize the length and self-weight of the second tab part  160 , thereby preventing the distal end of the second electrode  112  of the electrode assembly  110  from being deformed. When it is required to connect the electrode assembly  110  to the upper can  130 , the length of the second tab part  160  may extend by the length of the second lead tab  162  by connecting the second lead tab  162  to the second electrode tab  161  to stably connect the electrode assembly  110  to the upper can  130 . 
     Thus, the button-type secondary battery  100  according to the first embodiment of the present invention may comprise the second tab part  160  provided with the second electrode tab  161  and the second lead tab  162  to prevent the electrode assembly  110  from being deformed, thereby stably connecting the electrode assembly  110  to the upper can  130 . 
     Referring to  FIG.  3   , the second electrode tab  161  has a length less than that of the second lead tab  162 . Thus, the length of the second electrode tab  161  coupled to the distal end of the second electrode  112  of the electrode assembly  110  may be significantly reduced to prevent the electrode assembly from being deformed. 
     Referring to  FIG.  4   , a thickness α 1  of the second electrode tab  161  is less than a thickness β 1  of the second lead tab  162 . Thus, the self-weight of the second electrode tab  161  may be significantly reduced to significantly prevent the electrode assembly from being deformed. 
     The second electrode tab  161  and the second lead tab  162  may be made of different metal materials through which are electrically conductive. That is, the second electrode tab  161  may be made of a metal material that is lighter than the second lead tab  162 . Thus, the self-weight of the second electrode tab  161  may be significantly reduced to significantly prevent the electrode assembly from being deformed. 
     Referring to  FIG.  5   , the second electrode tab  161  and the second lead tab  162  have the same thickness, and a width α 2  of the second electrode tab  161  is less than a width β 2  of the second lead tab  162 . Thus, the self-weight of the second electrode tab  161  may be significantly reduced to significantly prevent the electrode assembly from being deformed. 
     The second electrode tab  161  and the second lead tab  162  are disposed to partially overlap each other, and then, the overlapping portion of the second electrode tab  161  and the second lead tab  162  may be coupled to each other through welding. Thus, coupling force between the second electrode tab  161  and the second lead tab  162  may increase. 
     Referring to  FIG.  4   , a length of the overlapping portion A of the second electrode tab  161  and the second lead tab  162  is 1.5 mm to 10.0 mm, preferably 2.0 mm to 4.0 mm. The optimal length of the overlapping portion A is formed to be 2.5 mm. Here, if the length of the overlapping portion A is 1.5 mm or less, the welding is difficult, and if the length of the overlapping portion A is 10.0 mm or more, there is a problem in that the self-weight of the second tab part unnecessarily increases. 
     The second electrode tab  161  comprises a rear end  161   a  coupled to the distal end of the second electrode  112  disposed outside the electrode assembly  110 , a front end  161   b  coupled to the second lead tab  162 , and a withdrawal end  161   c  disposed between the rear end  161   a  and the front end  161   b  to match a surface of the electrode assembly  110  facing the upper can  130 . 
     Referring to  FIG.  6   , a length α 3  from the withdrawal end  161   c  to the front end  161   b  of the second electrode tab  161  is equal to or less than a width of the second electrode tab  161  or the second lead tab  162 . Particularly, each of the second electrode tab  161  and the second lead tab  162  has a length that is equal to the width of the second electrode tab  161  or the second lead tab  162  to stably perform the welding. 
     For example, the length α 3  from the withdrawal end  161   c  to the front end  161   b  of the second electrode tab  161  may be 10 mm to 40 mm. Thus, the length of the second electrode tab  161  withdrawn from the surface of the electrode assembly may be uniform, and as a result, uniformity of the product may be improved. 
     The length α 3  from the withdrawal end  161   c  to the front end  161   b  of the second electrode tab  161  has a length corresponding to 30% to 50% of a diameter of the electrode assembly. Preferably the length α 3  has a length corresponding to 40%. That is, when the length α 3  from the withdrawal end  161   c  to the front end  161   b  of the second electrode tab  161  is greater than 50% of the diameter of the electrode assembly, the self-weight of the second electrode tab may increase to cause deformation of the electrode assembly. 
     The rear end of the second lead tab overlapping the second electrode tab may extend up to the rear end  161   a  of the second electrode tab and may be bonded to the rear end of the second electrode tab. Thus, strength of the second electrode tab may be reinforced, and as a result, the deformation such as bending of the second electrode tab may be prevented. 
     The second lead tab  162  may be made of a flexible metal material. Thus, when the electrode assembly and the upper can are coupled to each other, the second lead tab  162  may be stably bent, and as a result, the breakage or folding of the second lead tab  162  may be prevented. 
     The insulating tape  170  for improving insulation properties is attached to the first tab part  150  and the second tab part  160 , and the insulating tape  170  is attached to surround the first tab part  150  or the second tab part  160  to prevent short circuit from occurring. 
     An insulator  180  is provided between the electrode assembly  110  and the lower can  120  or between the electrode assembly  110  and the upper can  130 , and the insulator  180  insulates the first electrode of the electrode assembly from the second tab part and insulates the second electrode of the electrode assembly from the first tab part. 
     Therefore, the button-type secondary battery  100  according to the first embodiment of the present invention comprises the second tab part provided with the second electrode tab and the second lead tab. Thus, when the secondary battery is manufactured, the length of the second tab part may selectively extend to prevent the electrode assembly from being deformed, thereby stably connecting the electrode assembly to the upper can. 
     Hereinafter, in descriptions of another embodiment of the present invention, constituents having the same function as the above-mentioned embodiment have been given the same reference numeral in the drawings, and thus duplicated description will be omitted. 
     [Button-Type Secondary Battery According to Second Embodiment of the Present Invention] 
     As illustrated in  FIG.  7   , a button-type secondary battery  100  according to a second embodiment of the present invention comprises a second tab part  160  provided with a second electrode tab  161  and a second lead tab  162 , and the second electrode tab  161  and the second lead tab  162  are coupled to each other through welding in a state in which ends of the second electrode tab  161  and the second lead tab  162 , which correspond to each other, overlap each other. 
     Here, the button-type secondary battery  100  according to the second embodiment of the present invention comprises a protection member  190  for improving insulation properties with respect to a coupled portion between the second electrode tab  161  and the second lead tab  162 , and the protection member  190  is attached to surround the coupled portion of the second electrode tab  161  and the second lead tab  162 . 
     The protection member  190  may be a silicone tape. 
     Therefore, the button-type secondary battery  100  according to the second embodiment of the present invention comprises the protection member  190  to prevent the electrode assembly from being damaged by the coupled portion of the second electrode tab  161  and the second lead tab  162  and also prevent the coupled portion of the second electrode tab  161  and the second lead tab  162  from being in contact with the first electrode. 
     [Button-Type Secondary Battery According to Third Embodiment of the Present Invention] 
     As illustrated in  FIG.  8   , a button-type secondary battery  100  according to a third embodiment of the present invention comprises a first tab part connecting a first electrode  111  of an electrode assembly  110  to a lower can  120 . 
     The first tab part  150  comprises a first electrode tab  151  and a first lead tab  152 . Here, the first electrode tab  151  is connected to the first electrode  111 , and the first lead tab  152  connects the first electrode tab  151  to the lower can  120 . 
     Therefore, in the button-type secondary battery  100  according to the third embodiment of the present invention, a length of the first tab part  150  may selectively extend to stably connect the electrode assembly  110  to the lower can  120 . 
     The first electrode tab  151  has a length less than that of the first lead tab  152 . Thus, it is possible to prevent the electrode assembly from being deformed by a self-weight of the first electrode tab  151 . 
     The first electrode tab  151  may have a thickness less than that of the first lead tab  152 , and the first electrode tab  151  may have a width greater than that of the first lead tab  152 . This has an effect of reducing the self-weight of the first tab part, and as a result, it is possible to prevent the electrode assembly from being deformed. 
     [Button-Type Secondary Battery According to Fourth Embodiment of the Present Invention] 
     As illustrated in  FIG.  9   , a button-type secondary battery  100  according to a fourth embodiment of the present invention comprises a second tab part  160  provided with a second electrode tab  161  and a second lead tab  162 . 
     Here, a lower groove  161   a  is formed in an end of the second electrode tab  161 , and an upper groove  162   a  fitted to the lower groove  161   a  is formed in an end of the second lead tab  162 . 
     That is, the lower groove  161   a  is formed to be opened toward an end of the second electrode tab  161 . The upper groove  162   a  is formed to be opened toward an end of the second lead tab  162 . Thus, since the second electrode tab  161  and the second lead tab  162  are coupled to each other through the lower groove  161   a  and the upper groove  162   a , an increase in thickness of the second electrode tab part may be minimized. 
     Therefore, in the button-type secondary battery  100  according to the fourth embodiment of the present invention, coupling force between the second electrode tab  161  and the second lead tab  162  may increase through the coupling of the lower groove  161   a  and the upper groove  162   a , and particularly, the increase in thickness of the second electrode tab part may be prevented. 
     Accordingly, the scope of the present invention is defined by the appended claims more than the foregoing description and the exemplary embodiments described therein. Various modifications made within the meaning of an equivalent of the claims of the invention and within the claims are to be regarded to be in the scope of the present invention. 
     DESCRIPTION OF THE SYMBOLS 
     
         
         
           
               100 : Button-type secondary battery 
               110 : Electrode assembly 
               111 : First electrode 
               112 : Second electrode 
               120 : Lower can 
               121 : Accommodation groove 
               130 : Upper can 
               140 : Gasket 
               141 : Outer gasket 
               142 : Inner gasket 
               143 : Connection gasket 
               150 : First tab part 
               160 : Second tab part 
               161 : Second electrode tab 
               162 : Second lead tab 
               170 : Insulating tape 
               180 : Insulator 
               190 : Protection member