Patent Publication Number: US-2022231322-A1

Title: Apparatus and Method for Manufacturing Electrode Assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims the benefit of the priority of Korean Patent Application No. 10-2019-0148933, filed on Nov. 19, 2019, which is hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to an apparatus and method for manufacturing an electrode assembly, which are capable of manufacturing a symmetrical electrode assembly in a new stacking manner. 
     BACKGROUND ART 
     In general, secondary batteries refer to chargeable and dischargeable batteries, unlike primary batteries that are not chargeable. The secondary batteries are being widely used in the high-tech electronic fields such as mobile phones, notebook computers, and camcorders. 
     The secondary batteries are classified into a can-type secondary battery, in which an electrode assembly is embedded in a metal can, and a pouch-type secondary battery in which an electrode assembly is embedded in a pouch. 
     The can-type secondary battery comprises an electrode assembly, an electrolyte, a can for accommodating the electrode assembly and the electrolyte, and a cap assembly mounted on an opening of the can, and the pouch-type secondary battery comprises an electrode assembly, an electrolyte, and a pouch accommodating the electrode assembly and the electrolyte. 
     The electrode assembly is classified into a stacked structure, a wound type (jelly-roll type) structure, or a stack/folding type structure. The stacked structure has a structure in which electrode units (a positive electrode, a separator, and a negative electrode) constituting the electrode assembly are stacked separately from each other. 
     However, it is very difficult to precisely align the electrode assembly in the stacked electrode assembly described above, and in particular, there is a problem in that a defect occurs while the electrode assembly is bent. 
     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 an apparatus and method for manufacturing an electrode assembly, in which a new stacking method for the electrode assembly is proposed to improve alignment of the electrode assembly and prevent the electrode assembly from being bent, and in particular, an electrode assembly of which upper and lower portions are symmetrical to each other is manufactured. 
     Technical Solution 
     A method for manufacturing an electrode assembly according to the present invention for achieving the above object comprises: a primary stack manufacturing step (S 10 ) in which a first electrode and a second electrode are alternately stacked with a separator therebetween on a top surface of a table so that the first electrode is stacked to be disposed at each of the uppermost end and the lowermost end; a secondary stack manufacturing step (S 20 ) in which the first electrode and the second electrode are alternately stacked with the separator therebetween on the primary stack so that the second electrode is stacked to be disposed at the lowermost end; a stack rotating step (S 30 ) in which the primary stack and the secondary stack, which are disposed on the table, are rotated together at an angle of 180° to change positions of the primary stack and the secondary stack; and an electrode assembly manufacturing step (S 40 ) in which the first electrode and the second electrode are alternately stacked with the separator therebetween on the primary stack so that the second electrode is stacked to be disposed at the lowermost end to manufacture a tertiary stack. 
     The stack rotating step (S 30 ) may comprise a process (S 31 ) of griping the primary stack and the secondary stack, which are disposed on the table, together by using a gripper, a process (S 32 ) of allowing the table to descend away from the primary stack, a process (S 33 ) of rotating the primary stack and the secondary stack together at an angle of 180° through the gripper, and a process (S 34 ) of allowing the table to ascend to be supported on the secondary stack. 
     The stack rotating step (S 30 ) may further comprise a process (S 31   a ) of photographing the lowermost end of the primary stack disposed on the table by using a first photographing part and measuring a primary reference line of the primary stack from a photographed image between the process (S 31 ) and the process (S 32 ), a process (S 35 ) of photographing the uppermost end of the primary stack by using a second photographing part and measuring a secondary reference line of the primary stack from a photographed image after the process (S 34 ), and a process (S 36 ) of comparing positions of the primary reference line and the secondary reference line with each other through a measuring part to calculate an error value. 
     The reference line may be a line by which the primary stack disposed on the table is equally divided to be symmetrical to each other in a width direction or a longitudinal direction. 
     In the electrode assembly manufacturing step (S 40 ), the separator, the first electrode, and the second electrode may move by the error value and be stacked on the primary stack. 
     The electrode assembly manufactured by the electrode assembly manufacturing step (S 40 ) may have a stacked structure of which upper and lower portions are symmetrical to each other with respect to a center. 
     The primary stack manufacturing step (S 10 ) may comprise a process of allowing the table to descend so that the uppermost end of the stack stacked on the table is constantly maintained in height. 
     The electrode assembly manufacturing step (S 40 ) may comprise a process of allowing the table to descend so that the uppermost end of the stack stacked on the table is constantly maintained in height. 
     In secondary stack manufacturing step (S 20 ), the second electrode may be stacked at the uppermost end. 
     In the electrode assembly manufacturing step (S 40 ), the second electrode may be stacked at the uppermost end. 
     The method may further comprise, after the electrode assembly manufacturing step (S 40 ), a bonding step (S 50 ) of pressing the electrode assembly at a set pressure to bond the electrode assembly. 
     An apparatus for manufacturing an electrode assembly according to the present invention comprises: a table; a loading member configured to alternately stack a first electrode and a second electrode with a separator therebetween on a top surface of the table to manufacture a stack; a gripper configured to grip the stack stacked on the table to rotate the stack at an angle of 180°; and a measuring member comprising a first photographing part configured to primarily photograph the lowermost end of the stack stacked on the table, a second photographing part configured to secondarily photograph the uppermost end of the stack after rotating the stack at the angle of 180°, and a measuring part configured to calculate an error value by comparing a primary reference line measured from a primarily photographed image of the stack with a secondary reference line measured from a secondarily photographed image of the stack. 
     The loading member may be configured to stack the separator, the first electrode, and the second electrode on the top surface of the stack while moving by the error value after rotating the stack at the angle of 180°. 
     When the gripper grips the stack, the table may descend away from the stack. 
     Each of the photographing parts may comprise an infrared camera. 
     Advantageous Effects 
     The method for manufacturing the secondary battery according to the present invention may comprise the primary stack manufacturing step (S 10 ), the secondary stack manufacturing step (S 20 ), the stack rotating step (S 30 ), and the electrode assembly manufacturing step (S 40 ). Therefore, the electrode assembly may be manufactured through the new stacking method, and the electrode assembly of which the upper and lower portions are symmetrical to each other, may be manufactured. Particularly, the electrode assembly may be prevented from being bent. 
     In addition, in the method for manufacturing the secondary battery according to the present invention, the stack rotating step (S 30 ) may comprise the process (S 31 ) of griping the primary and secondary stacks by using the gripper, the process (S 32 ) of allowing the table to descend away from the primary stack, the process (S 33 ) of rotating the primary and secondary stacks at the angle of 180° through the gripper, and the process (S 34 ) of allowing the table to ascend so as to be supported on the secondary stack. Therefore, the secondary stack may be stably rotated. 
     In addition, in the method for manufacturing the secondary battery according to the present invention, the stack rotating step (S 30 ) comprises the process of comparing the reference line of the primary stack before the rotation with the reference line of the primary stack after the rotation between the step (S 31 ) and the step (S 32 ). Therefore, it may be possible to check the position change of the primary stack, and thus, the stacked position may be corrected through the error value due to the changed position, thereby preventing the stacking failure from occurring. 
     In addition, in the method for manufacturing the secondary battery according to the present invention, the reference line may be set as the line by which the primary stack is equally divided to be symmetrical to each other in the width direction or the longitudinal direction. Therefore, the reference line of the radial unit may be set identically. 
     In addition, in the method for manufacturing the secondary battery according to the present invention, the electrode assembly manufacturing step (S 40 ) may be performed so that the separator, the first electrode, and the second electrode move by the error value and then are stacked on the secondary stack. Therefore, the stacking failure may be previously prevented. 
     In the method for manufacturing the secondary battery, the primary stack manufacturing step (S 10 ) may be performed so that the table on which the electrode and the separator are stacked constantly descends. Therefore, the height of the uppermost end of the stack stacked on the table may be constantly maintained to improve the stacking efficiency. 
     In the method for manufacturing the secondary battery, the electrode assembly manufacturing step (S 240 ) may be performed so that the table on which the secondary stack is disposed constantly descends. Therefore, the height of the uppermost end of the stack stacked on the table may be constantly maintained to improve the stacking efficiency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of an electrode assembly according to a first embodiment of the present invention. 
         FIG. 2  is a flowchart illustrating a method for manufacturing an electrode assembly according to a second embodiment of the present invention. 
         FIG. 3  is a cross-sectional view illustrating a primary stack manufacturing step (S 10 ) in the method for manufacturing the electrode assembly according to the second embodiment of the present invention. 
         FIG. 4  is a cross-sectional view illustrating a secondary stack manufacturing step (S 20 ) in the method for manufacturing the electrode assembly according to the second embodiment of the present invention. 
         FIGS. 5 to 8  are cross-sectional views illustrating a stack rotating step (S 30 ) in the method for manufacturing the electrode assembly according to the second embodiment of the present invention. 
         FIG. 9  is a cross-sectional view illustrating an electrode assembly manufacturing step (S 40 ) in the method for manufacturing the electrode assembly according to the second embodiment of the present invention. 
         FIG. 10  is a cross-sectional view illustrating a bonding step (S 50 ) in the method for manufacturing the electrode assembly according to the second 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. 
     [Electrode Assembly According to First Embodiment of the Present Invention] 
     As illustrated in  FIG. 1 , an electrode assembly  10  according to a first embodiment of the present invention comprises a primary stack  10   a , a secondary stack  10   b  disposed under the primary stack  10   a , and a tertiary stack  10   c  disposed on the primary stack  10   a.    
     Primary Stack 
     In the primary stack  10   a , a first electrode  11  and a second electrode  12  are alternately stacked with the separator  13  therebetween. Here, the first electrode  11  is disposed at each of the uppermost and lowermost ends. That is, in the primary stack  10   a , an upper portion and a lower portion have the same stacked structure with respect to the second electrode  12 , which is disposed between the upper and lower portions. 
     For example, the primary stack  10   a  has a five-layered structure in which the first electrode  11 , the separator  13 , the second electrode  12 , the separator  13 , and the first electrode  11  are sequentially stacked. 
     Secondary Stack 
     In the secondary stack  10   b , when viewed in  FIG. 1 , the secondary stack  10   b  is disposed under the primary stack  10   a , and the first electrode  11  and the second electrode are alternately stacked with the separator  13  therebetween. Here, the second electrode  12  is stacked to be disposed at the uppermost end corresponding to the primary stack  10   a . Alternatively, the separator  13  is interposed between the first electrode  11  disposed at the lowermost end of the primary stack  10   a  and the second electrode  12  disposed at the uppermost end of the secondary stack  10   b.    
     For example, the secondary stack  10   b  has a ten-layered structure in which the separator  13 , the second electrode  12 , the separator  13 , the first electrode  11 , the separator  13 , the second electrode  12 , the separator  13 , the first electrode  11 , the separator  13 , and the second electrode  12  are sequentially stacked in a vertical direction. Here, the second electrode  12  is also disposed at the lowermost end of the secondary stack  10   b.    
     Tertiary Stack 
     When viewed in  FIG. 1 , the tertiary stack  10   c  is disposed on the primary stack  10   a  and has a stacked structure that is symmetrical to the secondary stack  10   b  with respect to the primary stack  10   a.    
     In the tertiary stack  10   c , the first electrode  11  and the second electrode  12  are alternately stacked with the separator  13  therebetween on the primary stack  10   a . Here, the second electrode  12  is disposed at the lowermost end corresponding to the primary stack  10   a . Alternatively, the separator  13  is interposed between the first electrode  11  disposed at the uppermost end of the primary stack  10   a  and the second electrode  12  disposed at the lowermost end of the secondary stack  10   b.    
     For example, the tertiary stack  10   c  has a ten-layered structure in which the second electrode  12 , the separator  13 , the first electrode  11 , the separator  13 , the second electrode  12 , the separator  13 , the first electrode  11 , the separator  13 , the second electrode  12 , and the separator  13  are sequentially stacked in the vertical direction. Here, the second electrode  12  is also disposed at the uppermost end of the tertiary  10   c.    
     The first electrode is a positive electrode, and the second electrode is a negative electrode, and vice versa. 
     Therefore, in the electrode assembly  10  according to the first embodiment of the present invention, the tertiary stack  10   c , the primary stack  10   a , and the secondary stack  10   b  are stacked in the vertical direction, but the secondary stack  10   b  and the tertiary stack  10   c  have a symmetrically stacked structure with respect to the primary stack  10   a.    
     The electrode assembly  10  having the above-described structure according to the first embodiment of the present invention is manufactured using an apparatus  100  for manufacturing the electrode assembly. 
     [Apparatus for Manufacturing Electrode Assembly According to Second Embodiment of the Present Invention] 
     Referring to  FIGS. 1, 5, and 10 , an apparatus  100  for manufacturing an electrode assembly according to a second embodiment of the present invention comprises a table  110 , a loading member  120  configured to alternately stack a first electrode and a second electrode with a separator therebetween on a top surface of the table  110 , a gripper  130  configured to grip the stack stacked on the table  110  to rotate the stack at an angle of 180°, a measuring member  140  comprising a first photographing part  141  configured to primarily photograph the lowermost end of the stack stacked on the table  110 , a second photographing part  142  configured to secondarily photograph the uppermost end of the stack after rotating the stack at the angle of 180°, and a measuring part  143  configured to calculate an error value by comparing a primary reference line measured from a primarily photographed image of the stack with a secondary reference line measured from a secondarily photographed image of the stack, and a bonding member  150  configured to bond the stack. 
     The loading member  120  is configured to stack the separator, the first electrode, and the second electrode on the top surface of the stack while moving by the error value after rotating the stack at the angle of 180°, thereby preventing stacking failure from occurring. 
     When the gripper  130  grips the stack, the table  110  may descend away from the stack to prevent the stack from being caught on the table  110  when the stack is rotated. 
     Each of the first and second photographing parts  141  and  142  may be an infrared camera and thus accurately photograph the stack disposed on the table  110  to measure a reference line of the stack. 
     Hereinafter, a method for manufacturing the electrode assembly by using the apparatus  100  for manufacturing the electrode assembly, which has the above-described constituents, according to the second embodiment of the present invention will be described. 
     [Method for Manufacturing Electrode Assembly According to Second Embodiment of the Present Invention] 
     As illustrated in  FIGS. 2 to 10 , a method for manufacturing an electrode assembly according to a second embodiment of the present invention comprises a primary stack manufacturing step (S 10 ), a secondary stack manufacturing step (S 20 ), a stack rotating step (S 30 ), an electrode assembly manufacturing step (S 40 ) in which a tertiary stack is manufactured to complete an electrode assembly, and a bonding step (S 50 ) of bonding the primary stack, the secondary stack, and the tertiary stack to each other. 
     Primary Stack Manufacturing Step 
     As illustrated in  FIG. 3 , in the primary stack manufacturing step (S 10 ), a first electrode  11  and a second electrode  12  are alternately stacked with a separator  13  therebetween on a top surface of a table  110  to manufacture a primary stack  10   a . Here, the first electrode  11  is stacked to be disposed at each of the uppermost and lowermost ends of the primary stack  10   a . The table  110  has a flat top surface so that the primary stack  10   a  is disposed horizontally. 
     For example, in the primary stack manufacturing step (S 10 ), a loading box in which the first electrode  11  is loaded, a loading box in which the second electrode  12  is loaded, and a loading box in which the separator  13  is loaded are prepared. Then, the first electrode  11 , the second electrode  12 , and the separator  13 , which are loaded in the loading boxes, are selectively drawn out by using a loading member  120  so as to be stacked on the top surface of the table  110 . That is, the first electrode  11 , the separator  13 , the second electrode  12 , the separator  13 , and the first electrode  11  are sequentially stacked on the top surface of the table  110  using the loading member  120  to manufacture a primary stack  10   a  having a five-layered structure. 
     The primary stack manufacturing step (S 10 ) further comprises a process of pressing the primary stack  10   a  at a set pressure to bond the primary stack  10   a . Thus, the first electrode  11 , the second electrode  12 , and the separator  13 , which are disposed in the primary stack  10   a , may be prevented from moving. 
     The primary stack manufacturing step (S 10 ) further comprises a process of allowing the table  110  to descend so that the uppermost end of the stack stacked on the table  10  is constantly maintained in height. Therefore, it is not necessary to adjust the height of the loading member  120 , and thus, the electrodes and the separators may be stably stacked on the table  110 . 
     Secondary Stack Manufacturing Step 
     As illustrated in  FIG. 4 , in the secondary stack manufacturing step (S 20 ), a secondary stack  10   b  is manufactured on a top surface of the primary stack  10   a  disposed on the table  110 . 
     That is, in the secondary stack manufacturing step (S 20 ), the first electrode  11  and the second electrode  12  are alternately stacked with the separator  13  therebetween on the primary stack  10   a  to manufacture the secondary stack  10   b . Here, the second electrode  12  is stacked to be disposed at the lowermost end of the secondary stack  10   b.    
     For example, in the secondary stack manufacturing step (S 20 ), a secondary stack  10   b  having a ten-layered structure in which the second electrode  12 , the separator  13 , the first electrode  11 , the separator  13 , the second electrode  12 , the separator  13 , the first electrode  11 , the separator  13 , the second electrode  12 , and the separator  13  are sequentially stacked on the top surface of the primary stack  10   a  disposed on the table  110  in the vertical direction is manufactured. Here, upper and lower portions of the secondary stack have a symmetrically stacked structure with respect to a center of the secondary stack. 
     Thus, the primary stack  10   a  and the secondary stack  10   b  are disposed on the top surface of the table  110 . 
     The secondary stack manufacturing step (S 20 ) further comprises a process of bonding the first stack  10   a  and the secondary stack  10   b . That is, the primary stack  10   a  and the secondary stack  10   b , which are disposed on the table  110 , may be pressed at the set pressure to improve bonding force between the primary stack  10   a  and the secondary stack  10   b.    
     Stack Rotating Step 
     As illustrated in  FIGS. 5 to 8 , in the stack rotating step (S 30 ), the primary stack  10   a  and the secondary stack  10   b  are rotated so that the primary stack  10   a  is disposed on the secondary stack  10   b.    
     That is, the stack rotating step (S 30 ) comprises a process (S 31 ) of griping the primary stack  10   a  and the secondary stack  10   b , which are disposed on the table  110 , together by using a gripper  130 , a process (S 32 ) of allowing the table  110  to descend away from the secondary stack  10   b  so that the table  110  is not caught when the primary stack  10   a  and the secondary stack  10   b  are rotated, a process (S 33 ) of rotating the primary stack  10   a  and the secondary stack  10   b  together at an angle of 180° through the gripper  130 , and a process (S 34 ) of allowing the table  110  to ascend to be supported on the secondary stack  10   b.    
     That is, the primary stack  10   a  is disposed at an upper side, and the secondary stack  10   b  is disposed at a lower side. 
     The stack rotating step (S 30 ) comprises a process of measuring a position error before and after the rotation of the primary stack  10   a  and the secondary stack  10   b  by using a measuring member  140 . The measuring member  140  comprises a first photographing part  141 , a second photographing part  142  and a measuring part  143 . 
     That is, the stack rotating step (S 30 ) comprises a process (S 31   a ) of photographing the lowermost end of the primary stack  10   a  disposed on the table by using the first photographing part  141  and measuring a primary reference line O 1  of the primary stack  10   a  from a photographed image between the process (S 31 ) and the process (S 32 ), a process (S 35 ) of photographing the uppermost end of the primary stack  10   a  by using the second photographing part  142  and measuring a secondary reference line O 2  of the primary stack  10   a  from a photographed image after the process (S 34 ), and a process (S 36 ) of comparing positions of the primary reference line O 1  and the secondary reference line O 2  with each other through the measuring part  143  to calculate an error value. 
     That is, in the stack rotating step (S 30 ), after the rotation of the primary stack  10   a  and the secondary stack  10   b , it is measured whether a position change occurs. 
     The primary and secondary reference lines refer to lines by which the primary stack  10   a  disposed on the table  110  is equally divided to be symmetrical to each other in a width direction or a longitudinal direction. 
     Electrode Assembly Manufacturing Step 
     As illustrated in  FIG. 9 , in the electrode assembly manufacturing step (S 40 ), a tertiary stack  10   c  is manufactured on the top surface of the primary stack  10   a  to complete an electrode assembly  10 . 
     That is, in the electrode assembly manufacturing step (S 40 ), the first electrode  11  and the second electrode  12  are alternately stacked with the separator  13  therebetween on the primary stack  10   a  disposed on the table  110  to manufacture the tertiary stack  10   c . Here, the second electrode  12  is stacked at the lowermost end of the tertiary stack  10   c.    
     Thus, in the electrode assembly manufacturing step (S 40 ), the electrode assembly  10  in which the tertiary stack  10   c , the primary stack  10   a , and the secondary stack  10   b  are sequentially stacked may be completed. 
     Here, in the electrode assembly manufacturing step (S 40 ), the separator, the first electrode, and the second electrode may move by the error value measured in the stack rotating step (S 30 ) and then be stacked on the primary stack  10   a  to prevent stacking failure from occurring. 
     For example, in the electrode assembly manufacturing step (S 40 ), a tertiary stack  10   b  having a ten-layered structure in which the second electrode  12 , the separator  13 , the first electrode  11 , the separator  13 , the second electrode  12 , the separator  13 , the first electrode  11 , the separator  13 , the second electrode  12 , and the separator  13  are sequentially stacked on the top surface of the primary stack  10   a  disposed on the table  110  in the vertical direction is manufactured. Here, in the electrode assembly manufacturing step (S 40 ), the second electrode  12  is stacked at the uppermost end, and accordingly, the tertiary stack has a stacked structure of which upper and lower portions are symmetrical to each other with respect to the center. 
     Particularly, the secondary and tertiary stacks  10   b  and  10   c  have a symmetrically stacked structure with respect to the primary stack  10   a , and accordingly, a symmetrical electrode assembly may be easily manufactured. Particularly, since the secondary and tertiary stacks have the symmetrical structure, it is possible to prevent the finished-product electrode assembly from being bent. 
     The electrode assembly manufacturing step (S 40 ) further comprises a process of allowing the table  110  to descend so that the uppermost end of the stack stacked on the table  110  is constantly maintained in height. Therefore, since there is no need to adjust the height of the loading member  120 , the electrodes and the separators may be stably stacked. 
     Bonding Step 
     As illustrated in  FIG. 10 , in the bonding step (S 50 ), the electrode assembly  10  constituted by the primary, secondary, and tertiary stacks  10   a ,  10   b , and  10   c  is bonded using the bonding member  150 . Therefore, the finished-product electrode assembly  10  may be manufactured. 
     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 : Apparatus for manufacturing electrode assembly 
               110 : Table 
               120 : Loading member 
               130 : Gripper 
               140 : Measuring member 
               150 : Bonding member