Patent Publication Number: US-2023148346-A1

Title: Apparatus and Method for Manufacturing Unit Cells

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/KR2021/009293 filed on Jul. 20, 2021, which claims priority from Korean Patent Application No. 10-2020-0089911, filed on Jul. 20, 2020, and now published as WO 2022/019599 A1, each of which are hereby incorporated by reference in their entireties. 
    
    
     FIELD 
     The present invention relates to an apparatus and method for manufacturing unit cells, and more particularly, to an apparatus and method for manufacturing unit cells, capable of easily checking and correcting deviation of an electrode from the normal position when the unit cell is manufactured by stacking the electrode and a separator sheet. 
     BACKGROUND 
     In general, there are several types of secondary batteries such as nickel cadmium batteries, nickel hydrogen batteries, lithium-ion batteries, and lithium-ion polymer batteries. These secondary batteries have been applied to and used for not only small products such as digital cameras, P-DVDs, MP3Ps, cellular phones, PDAs, portable game devices, power tools, and E-bikes, but also large products requiring high power such as electric vehicles and hybrid vehicles, and power storage devices or backup-power storage devices for storing surplus generated power and new renewable energy. 
     In order to manufacture the secondary batteries, first of all, electrode active material slurry is applied to a positive electrode collector and a negative electrode collector to manufacture a positive electrode and a negative electrode, and the positive electrode and the negative electrode are stacked on both sides of a separator to form an electrode assembly having a predetermined shape. Subsequently, the electrode assembly is accommodated in a battery case, and the battery case is sealed after injecting an electrolyte therein. 
     The electrode assemblies are classified into various types. For example, there are: a simple stack type in which positive electrodes, separators, and negative electrodes are simply stacked in an alternate and continuous manner without manufacturing unit cells; a lamination and stack (L&amp;S) type in which, first, unit cells are manufactured by using positive electrodes, separators, and negative electrodes, and then, the unit cells are stacked; a stack and folding (S&amp;F) type in which a plurality of electrodes or unit cells are spaced and attached on one surface of a separator sheet having a length elongated to the one side, and then, the separator sheet is repeatedly folded from one end in the same direction; and a Z-folding type in which a plurality of electrodes or unit cells are alternately attached on one surface and the other surface of a separator sheet having a length elongated to the one side, and then, the separator sheet is folded from one end in a specific direction and then folded in the opposite direction in an alternate and repetitive manner. 
     Among these types, a unit cell may be manufactured first in order to manufacture an electrode assembly in the lamination and stack type, the stack and folding type, or the Z-folding type. Generally, in order to manufacture the unit cell, separators are respectively stacked on the top and bottom surfaces of a central electrode while the central electrode is moved to one side by a conveyor belt or the like. Subsequently, an upper electrode is further stacked on the uppermost end. If necessary, a lower electrode may be further stacked on the lowermost end. Then, a laminating process is performed to apply heat and pressure to a stack in which the electrodes and the separators are stacked. By performing this laminating process, the electrodes and the separators are bonded, and the unit cell may be securely formed. 
     However, according to the related art, all of a plurality of separator sheets and electrode sheets move on a single line in the same direction. Also, when an electrode sheet is cut at preset intervals by using a cutter to manufacture an electrode, the electrode is immediately placed on a separator sheet. Thus, it is not easy to check whether or not the electrode deviates from the normal position after the electrode sheet is cut. Moreover, even if the electrode deviates from the normal position, it is not easy to correct the deviation. 
     Also, the position of the central electrode stacked between two separator sheets is recognized by a sensor, and then, the timing of inputting the other electrodes is determined. However, since the central electrode is stacked and hidden between the two separator sheets, the position of an electrode tab of the central electrode, which protrudes to one side of the separator, is recognized by a sensor in order to recognize the position of the central electrode. Here, when a portion of the electrode tab is damaged, folded, or bent, the sensor does not accurately recognize the position of the central electrode. Accordingly, a defect occurs at a unit cell. Furthermore, when these electrodes are continuously input, defects occur continuously at unit cells. 
     PRIOR ART DOCUMENTS 
     Patent Documents 
     
         
         (Patent Document 1) Japanese Patent Publication No. 2019-139961 
       
    
     SUMMARY OF THE DISCLOSURE 
     An object of the present invention for solving the above problems is to provide an apparatus and method for manufacturing unit cells, capable of easily checking and correcting deviation of an electrode from the normal position when the unit cell is manufactured by stacking the electrode and a separator sheet. 
     The objects of the present invention are not limited to the aforementioned objects, but other objects not described herein will be clearly understood by those skilled in the art from descriptions below. 
     To solve the above problems, an apparatus for manufacturing unit cells according to an embodiment of the present invention includes: a lower separator reel from which a lower separator sheet is unwound; a first feeding roller configured to move the lower separator sheet in a first direction; a first conveyor configured to move a first electrode in a second direction parallel to the first direction; a first header configured to convey the first electrode from the first conveyor and place the first electrode on a top surface of the lower separator sheet; an upper separator reel from which an upper separator sheet is unwound; a second feeding roller configured to move, in the first direction, a first stack in which the lower separator sheet, the first electrode, and the upper separator sheet are stacked in this order; a second conveyor configured to move a second electrode in the second direction; a second header configured to convey the second electrode from the second conveyor and place the second electrode on a top surface of the upper separator sheet; and a cutter configured to cut, at preset intervals, a second stack in which the lower separator sheet, the first electrode, the upper separator sheet, and the second electrode are stacked in this order. 
     Also, the apparatus may further include a first vision sensor which is disposed between the lower separator sheet and the first conveyor and captures an image of the first electrode before the first electrode is placed on the top surface of the lower separator sheet. 
     Also, the apparatus may further include a second vision sensor which is disposed between the first stack and the second conveyor and captures an image of the second electrode before the second electrode is placed on the top surface of the upper separator sheet. 
     Also, the apparatus may further include a third vision sensor which is disposed above the first conveyor to capture an image of the first electrode. 
     Also, the apparatus may further include a fourth vision sensor which is disposed above the second conveyor to capture an image of the second electrode. 
     Also, the first header may convey the first electrode in a third direction perpendicular to both the first direction and the second direction, and the second header may convey the second electrode in a fourth direction parallel to the third direction and perpendicular to both the first direction and the second direction. 
     Also, the apparatus may further include first nip rollers which are respectively disposed on both surfaces of the lower separator sheet and the first electrode, wherein when the first electrode is placed on the top surface of the lower separator sheet, the first nip rollers press the lower separator sheet and the first electrode while rotating. 
     Also, the apparatus may further include second nip rollers which are respectively disposed on both surfaces of the second stack and press the second stack while rotating. 
     Also, the apparatus may further include a magazine in which the plurality of unit cells are sequentially accommodated and stacked. 
     Also, the first conveyor and the second conveyor may be arranged in a line along the second direction. 
     Also, the apparatus may further include: a first electrode reel from which is unwound a first electrode sheet in which the first electrode is formed; and a second electrode reel from which is unwound a second electrode sheet in which the second electrode is formed. 
     To solve the above problems, a method for manufacturing unit cells according to an embodiment of the present invention includes: unwinding a lower separator sheet from a lower separator reel and moving the lower separator sheet in a first direction; moving a first electrode in a second direction parallel to the first direction by using a first conveyor; conveying the first electrode from the first conveyor and placing the first electrode on a top surface of the lower separator sheet, by using a first header; unwinding an upper separator sheet from an upper separator reel and moving the upper separator sheet in the first direction; stacking the upper separator sheet above the lower separator sheet and on a top surface of the first electrode to form a first stack; moving a second electrode in the second direction by using a second conveyor; conveying the second electrode from the second conveyor and placing the second electrode on a top surface of the upper separator sheet, by using a second header, thereby forming a second stack; and cutting the second stack at preset intervals by using a cutter to manufacture a unit cell. 
     Also, in the placing of the first electrode on the top surface of the lower separator sheet, a first vision sensor, which is disposed between the lower separator sheet and the first conveyor, may capture an image of the first electrode before the first electrode is placed on the top surface of the lower separator sheet. 
     Also, in the placing of the second electrode on the top surface of the upper separator sheet, a second vision sensor, which is disposed between the first stack and the second conveyor, may capture an image of the second electrode before the second electrode is placed on the top surface of the upper separator sheet. 
     Also, in the moving of the first electrode in the second direction, a third vision sensor disposed above the first conveyor may capture an image of the first electrode. 
     Also, in the moving of the second electrode in the second direction, a fourth vision sensor disposed above the second conveyor may capture an image of the second electrode. 
     Other specific features of the present invention are included in the detailed description and drawings. 
     The embodiments of the present invention may have at least the following effects. 
     The electrode is moved by the separate header. Thus, even if the electrode deviates from the normal position, the deviation may be easily corrected. 
     Also, instead of directly checking the position of the electrode by using the electrode tab, the position of the electrode itself is directly checked by the vision sensor. Thus, it may be easily checked whether or not the electrode deviates from the normal position, and the occurrence of defects of the unit cell may be prevented. 
     Also, the first conveyor is disposed close to the input position of the first electrode, and the second conveyor is disposed close to the input position of the second electrode. Thus, the first electrode and the second electrode may be moved to the appropriate input positions along the shortest route, thus reducing unnecessary movement and efficiently manufacturing the unit cells. 
     Also, the conveyors for conveying and supplying the electrodes are disposed in parallel to one side of the separator sheet. Thus, the overall volume of the equipment may also be reduced. 
     The effects according to the present invention are not limited to those exemplified above, and more various effects are included in the present specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a flowchart of a method for manufacturing unit cells according to an embodiment of the present invention. 
         FIG.  2    is a schematic view of an apparatus  1  for manufacturing unit cells according to an embodiment of the present invention. 
         FIG.  3    is a schematic plan view showing in detail the apparatus  1  for manufacturing unit cells according to an embodiment of the present invention. 
         FIG.  4    is a schematic view of an apparatus  1   a  for manufacturing unit cells according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Advantages and features of the present invention, and implementation methods thereof will be clarified through following embodiments described in detail with reference to the accompanying drawings. The present invention may, however, be embodied in various different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art to which the present invention belongs. Further, the present invention is defined only by scopes of claims. Like reference numerals refer to like elements throughout. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. Also, terms as defined in a generally used dictionary are not construed ideally or excessively unless defined apparently and specifically. 
     The terms used in this specification are used only to explain embodiments while not limiting the present invention. In this specification, the singular forms include the plural forms as well, unless the context clearly indicates otherwise. The meaning of “comprises” and/or “comprising” used in the specification does not exclude the presence or addition of one or more components other than the mentioned component. 
     Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       FIG.  1    is a flowchart of a method for manufacturing unit cells according to an embodiment of the present invention. 
     According to an embodiment of the present invention, an electrode is moved by a separate header. Thus, even if the electrode deviates from a normal position, the deviation may be easily corrected. Also, instead of directly checking the position of an electrode by using an electrode tab, the position of the electrode itself is directly checked by a vision sensor. Thus, it may be easily checked whether or not the electrode deviates from the normal position, and the occurrence of defects of a unit cell  2  may be prevented. Also, a first conveyor  31  is disposed close to an input position of a first electrode  1112 , and a second conveyor  32  is disposed close to an input position of a second electrode  1122 . Thus, the first electrode  1112  and the second electrode  1122  may be moved to the appropriate input positions along the shortest route, thus reducing unnecessary movement and efficiently manufacturing the unit cell  2 . Also, the conveyors for conveying and supplying the electrodes are disposed in parallel to one side of a separator sheet. Thus, the overall volume of the equipment may also be reduced. 
     To this end, a method for manufacturing unit cells according to an embodiment of the present invention includes: unwinding a lower separator sheet  1211  from a lower separator reel  121  and moving the lower separator sheet in a first direction D 1 ; moving a first electrode  1112  in a second direction D 2  parallel to the first direction D 1  by using a first conveyor  31 ; conveying the first electrode  1112  from the first conveyor  31  and placing the first electrode on a top surface of the lower separator sheet  1211 , by using a first header  141 ; unwinding an upper separator sheet  1221  from an upper separator reel  122  and moving the upper separator sheet in the first direction D 1 ; stacking the upper separator sheet  1221  above the lower separator sheet  1211  and on a top surface of the first electrode  1112  to form a first stack  21 ; moving a second electrode  1122  in the second direction D 2  by using a second conveyor  32 ; conveying the second electrode  1122  from the second conveyor  32  and placing the second electrode on a top surface of the upper separator sheet  1221 , by using a second header  142 , thereby forming a second stack  22 ; and cutting the second stack  22  at preset intervals by using a cutter  17  to manufacture a unit cell  2 . 
     Hereinafter, each of the processes illustrated in the flowchart of  FIG.  1    will be described in detail with reference to  FIGS.  2  and  3   . 
       FIG.  2    is a schematic view of an apparatus  1  for manufacturing unit cells according to an embodiment of the present invention. 
     As illustrated in  FIG.  2   , the apparatus  1  for manufacturing unit cells according to an embodiment of the present invention includes: a lower separator reel  121  from which a lower separator sheet  1211  is unwound; a first feeding roller  131  which moves the lower separator sheet  1211  in a first direction D 1 ; a first conveyor  31  which moves a first electrode  1112  in a second direction D 2  parallel to the first direction D 1 ; a first header  141  which conveys the first electrode  1112  from the first conveyor  31  and places the first electrode on a top surface of the lower separator sheet  1211 ; an upper separator reel  122  from which an upper separator sheet  1221  is unwound; a second feeding roller  132  which moves, in the first direction D 1 , a first stack  21  in which the lower separator sheet  1211 , the first electrode  1112 , and the upper separator sheet  1221  are stacked in this order; a second conveyor  32  which moves a second electrode  1122  in the second direction D 2 ; a second header  142  which conveys the second electrode  1122  from the second conveyor  32  and places the second electrode on a top surface of the upper separator sheet  1221 ; and a cutter  17  which cuts, at preset intervals, a second stack  22  in which the lower separator sheet  1211 , the first electrode  1112 , the upper separator sheet  1221 , and the second electrode  1122  are stacked in this order. 
     The lower separator reel  121  is a reel on which the lower separator sheet  1211  is wound, and the lower separator sheet  1211  is unwound from the lower separator reel  121 . Also, the first feeding roller  131  moves the lower separator sheet  1211  in the first direction D 1 . Meanwhile, the first conveyor  31  moves the first electrode  1112  in the second direction D 2  parallel to the first direction D 1  in which the lower separator sheet  1211  moves. Thus, the first electrode  1112  and the lower separator sheet  1211  move in parallel to each other. 
     Subsequently, the first electrode  1112  adheres to the first header  141 , and is then conveyed from the first conveyor  31  and placed on the top surface of the lower separator sheet  1211 . By repeating this process, a plurality of first electrodes  1112  may be stacked on the lower separator sheet  1211  while being spaced in a line in a longitudinal direction of the lower separator sheet  1211 . 
     A first nip roller  151  may be provided in plurality, and may be disposed on each of both surfaces of the lower separator sheet  1211  and the first electrode  1112 . Also, when the first electrode  1112  is placed on the top surface of the lower separator sheet  1211 , the first nip rollers  151  may press the lower separator sheet  1211  and the first electrode  1112  while rotating. Accordingly, the lower separator sheet  1211  and the first electrode  1112  may be bonded to each other more firmly. 
     Meanwhile, the upper separator reel  122  is a reel on which the upper separator sheet  1221  is wound, and the upper separator sheet  1221  is unwound from the upper separator reel  122 . Also, the upper separator sheet  1221  is stacked on the top surface of the first electrode  1112 . Accordingly, a first stack  21  is formed in which the lower separator sheet  1211 , the first electrode  1112 , and the upper separator sheet  1221  are stacked in this order. The first stack  21  may be formed such that the plurality of first electrodes  1112  are stacked between the separator sheets  1211  and  1221  while being spaced in a line in the longitudinal directions of the separator sheets  1211  and  1221 . Also, a second feeding roller  132  moves the first stack  21  in the first direction D 1 . Meanwhile, the second conveyor  32  moves the second electrode  1122  in the second direction D 2  parallel to the first direction D 1  in which the first stack  21  moves. Thus, the second electrode  1122  and the first stack  21  move in parallel to each other. 
     The first conveyor  31  and the second conveyor  32  move the first electrode  1112  and the second electrode  1122  in the second direction D 2 , respectively. Thus, the first conveyor  31  and the second conveyor  32  may be disposed in a line along the second direction D 2 . Particularly, since the first electrode  1112  is placed on the separator sheet earlier than the second electrode  1122 , the first conveyor  31  may be disposed in front of the second conveyor  32 . As described above, the conveyors for conveying and supplying the electrodes are not disposed in series with respect to a traveling direction, but disposed in parallel to one side of the separator sheets. Thus, the overall volume of the equipment may also be reduced. 
     Subsequently, the second electrode  1122  adheres to the second header  142 , and is then conveyed from the second conveyor  32  and placed on the top surface of the upper separator sheet  1221 . Accordingly, a second stack  22  is formed in which the lower separator sheet  1211 , the first electrode  1112 , the upper separator sheet  1221 , and the second electrode  1122  are stacked in this order. The second stack  22  may be formed such that a plurality of second electrodes  1122  are stacked on the upper separator sheet  1221  while being spaced in a line in the longitudinal direction of the upper separator sheet  1221 . Since the first electrode  1112  and the second electrode  1122  have different sizes, distances therebetween may be different. However, preferably, the first electrode  1112  and the second electrode  1122  are disposed such that the centers thereof are aligned with each other. 
     As described above, the first electrode  1112  and the second electrode  1122  are not input directly, but are moved by the separate headers. Thus, even if the electrode deviates from the normal position, the deviation may be easily checked and corrected. 
     Each of the first electrode  1112  and the second electrode  1122  may be manufactured by applying slurry of an electrode active material, a conductive material, and a binder onto an electrode collector and then drying and pressing the same. According to an embodiment of the present invention, the first electrode  1112  and the second electrode  1122  may be manufactured in a separate electrode manufacturing process. Also, the first electrode  1112  may be supplied to a first electrode magazine  311  or a first electrode table (not shown) provided on one side of the lower separator sheet  1211 , and then move to the first conveyor  31 . In addition, the second electrode  1122  may be supplied to a second electrode magazine  321  or a second electrode table (not shown) provided on one side of the first stack  21 , and then move to the second conveyor  32 . Here, the first electrode  1112  and the second electrode  1122  may be electrodes having different polarities. That is, when the first electrode  1112  is a positive electrode, the second electrode  1122  may be a negative electrode. When the first electrode  1112  is a negative electrode, the second electrode  1122  may be a positive electrode. 
     A second nip roller  152  may be provided in plurality, and may be disposed on each of both surfaces of the second stack  22 . Also, it may press the second stack  22  while rotating. Accordingly, the inner parts of the second stack  22  may be bonded to each other more firmly. 
     A laminator laminates the second stack  22 , in which the electrodes  1112  and  1122  and the separator sheets  1211  and  1221  are stacked, by heating and pressing the same. The laminating is referred to as heating and the pressing a stack  20  to bond the electrodes  1112  and  1122  and the separator sheets  1211  and  1221 . The laminator may include a heating roller  16  that heats and presses the stack  20  while rotating as illustrated in  FIG.  2   , and may include a heater (not shown) that uniformly heats and presses the entire surface of the stack  20 . 
     The method for manufacturing unit cells according to an embodiment of the present invention may be performed as below by using the apparatus  1  for manufacturing unit cells. 
     As illustrated in  FIG.  2   , first of all, the lower separator sheet  1211  is unwound from the lower separator reel  121  and moves in the first direction D 1  (S 101 ). Also, the first electrode  1112 , which has been manufactured in the separate electrode manufacturing process, is supplied to the first electrode magazine  311  or the first electrode table (not shown) provided on one side of the lower separator sheet  1211 . Subsequently, the first conveyor  31  moves the first electrode  1112  in the second direction D 2  parallel to the first direction D 1  (S 102 ). Then, the first electrode  1112  adheres to the first header  141 , and is then conveyed from the first conveyor  31  and placed on the top surface of the lower separator sheet  1211  (S 103 ). 
     Meanwhile, the upper separator sheet  1221  is unwound from the upper separator reel  122  and moves in the first direction D 1  (S 104 ). As the upper separator sheet  1221  is stacked on the top surface of the first electrode  1112 , the first stack  21  is formed. Also, the second electrode  1122 , which has been manufactured in the separate electrode manufacturing process, is supplied to the second electrode magazine  321  or the second electrode table (not shown) provided on one side of the first stack  21 . Subsequently, the second conveyor  32  moves the second electrode  1122  in the second direction D 2  parallel to the first direction D 1  (S 105 ). Then, the second electrode  1122  adheres to the second header  142  and is conveyed from the second conveyor  32 . Then, the second electrode  1122  is placed on the top surface of the upper separator sheet  1221  (S 106 ). Accordingly, the second stack  22  is formed. Also, as the second stack  22  is cut at preset intervals by the cutter  17 , the unit cell  2  may be manufactured. 
     Meanwhile, unit cells  2  formed by cutting the second stack  22  are sequentially accommodated and stacked in a magazine  18 . That is, when the unit cell  2  is formed, the unit cells  2  may be inserted into the magazine  18  one by one and sequentially stacked therein. Accordingly, an electrode assembly according to an embodiment of the present invention may be manufactured. 
       FIG.  3    is a schematic plan view showing in detail the apparatus  1  for manufacturing unit cells according to an embodiment of the present invention. 
     As illustrated in  FIG.  3   , the apparatus  1  for manufacturing unit cells according to an embodiment of the present invention further includes: a first vision sensor  191  which is disposed between the lower separator sheet  1211  and the first conveyor  31  and captures an image of the first electrode  1112  before the first electrode  1112  is placed on the top surface of the lower separator sheet  1211 ; a second vision sensor  192  which is disposed between the first stack  21  and the second conveyor  32  and captures an image of the second electrode  1122  before the second electrode  1122  is placed on the top surface of the upper separator sheet  1221 ; a third vision sensor  193  which is disposed above the first conveyor  31  to capture an image of the first electrode  1112 ; and a fourth vision sensor  194  which is disposed above the second conveyor  32  to capture an image of the second electrode  1122 . 
     The images are acquired as the first to fourth vision sensors  191 ,  192 ,  193 , and  194  capture the images of specific regions and receive image signals with respect to the specific regions. To this end, the vision sensor generally includes an image capturing element such as a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS). In particular, the first to fourth vision sensors  191 ,  192 ,  193 , and  194  according to an embodiment of the present invention may capture the images of the first electrode  1112  before placed on the lower separator sheet  1211 , the second electrode  1122  before placed on the top surface of the upper separator sheet  1221 , the first electrode  1112  moved by the first conveyor  31 , and the second electrode  1122  moved by the second conveyor  32 , respectively. Accordingly, the images may be acquired. 
     Meanwhile, although not illustrated in the drawings, the apparatus  1  for manufacturing unit cells according to an embodiment of the present invention may further include a control unit (not shown) which may determine, by using the images of the first electrode  1112  and the second electrode  1122 , whether or not the first electrode  1112  and the second electrode  1122  have defects. The control unit may compare the acquired images with pre-stored images of a first electrode  1112  and a second electrode  1122  having good qualities, and identify whether or not the first electrode  1112  and the second electrode  1122  have defects or are damaged with regard to the sizes, shapes, positions, or the like. 
     The first vision sensor  191  captures the image of the first electrode  1112  before the first electrode  1112  is placed on the top surface of the lower separator sheet  1211 . The first vision sensor  191  is disposed between the lower separator sheet  1211  and the first conveyor  31 , and may capture an image of a state in which the first electrode  1112  is conveyed while adhering to the first header  141 . Accordingly, it is easily identified whether or not the first electrode  1112  has the defect with respect to the position. If there is a defect in position, the position of the first electrode  1112  may be corrected before placed on the lower separator sheet  1211 . However, the embodiment is not limited thereto. The first vision sensor may be disposed above the lower separator sheet  1211  to capture an image of the first electrode  1112  placed on the lower separator sheet  1211 . 
     The second vision sensor  192  captures the image of the second electrode  1122  before the second electrode  1122  is placed on the top surface of the upper separator sheet  1221 . The second vision sensor  192  is disposed between the first stack  21  and the second conveyor  32 , and may capture an image of a state in which the second electrode  1122  is conveyed while adhering to the second header  142 . Accordingly, it is easily identified whether or not the second electrode  1122  has the defect with respect to the position. If there is a defect in position, the position of the second electrode  1122  may be corrected before placed on the upper separator sheet  1221 . However, the embodiment is not limited thereto. The second vision sensor may be disposed above the first stack  21  to capture an image of the second electrode  1122  placed on the upper separator sheet  1221 . 
     The third vision sensor  193  is disposed above the first conveyor  31 , and may capture an image of the first electrode  1112  which is being moved by the first conveyor  31  before the first electrode  1112  adheres to the first header  141 . Accordingly, it is easily identified whether or not the first electrode  1112  has defects in quality, position, and the like. If there are defects, the electrode may be eliminated before adhering to the first header  141 . However, the embodiment is not limited thereto. The third vision sensor may be disposed above the first electrode magazine  311  to capture an image of the first electrode  1112  before moving to the first conveyor  31 . 
     The fourth vision sensor  194  is disposed above the second conveyor  32 , and may capture an image of the second electrode  1122  which is being moved by the second conveyor  32  before the second electrode  1122  adheres to the second header  142 . Accordingly, it is easily identified whether or not the second electrode  1122  has defects in quality, position, and the like. If there are defects, the electrode may be eliminated before adhering to the first header  142 . However, the embodiment is not limited thereto. The fourth vision sensor may be disposed above the second electrode magazine  321  to capture an image of the second electrode  1122  before moving to the second conveyor  32 . 
     As described above, instead of directly checking the position of the electrode by using the electrode tab, the position of the electrode itself is directly checked by the vision sensor. Accordingly, even when a portion of the electrode tab is damaged, folded, or bent, the position of the electrode may be accurately checked, and thus, the occurrence of defects of the unit cell  2  may be prevented. 
     According to an embodiment of the present invention, as illustrated in  FIG.  3   , the first conveyor  31  is disposed close to an input position of the first electrode  1112 , and the second conveyor  32  is disposed close to an input position of the second electrode  1122 . Thus, the first header  141  conveys the first electrode  1112  in a third direction D 3  perpendicular to both the first direction D 1  and the second direction D 2 , and the second header  142  conveys the second electrode  1122  in a fourth direction D 4  parallel to the third direction D 3  and perpendicular to both the first direction D 1  and the second direction D 2 . That is, all of the first header  141  and the second header  142  move perpendicular to both the first direction D 1  and the second direction D 2 . Accordingly, the first electrode  1112  and the second electrode  1122  may be moved to the appropriate input positions along the shortest route, thus reducing unnecessary movement and efficiently manufacturing the unit cell  2 . 
       FIG.  4    is a schematic view of an apparatus  1   a  for manufacturing unit cells according to another embodiment of the present invention. 
     According to an embodiment of the present invention, a first electrode  1112  and a second electrode  1122  may be manufactured in separate electrode manufacturing processes and then supplied. However, the apparatus  1   a  for manufacturing unit cells according to another embodiment of the present invention further includes a first electrode reel  111  from which is unwound a first electrode sheet  1111  in which the first electrode  1112  is formed and a second electrode reel  112  from which is unwound a second electrode sheet  1121  in which the second electrode  1122  is formed. That is, the first electrode  1112  and the second electrode  1122  may be manufactured directly by cutting the first electrode sheet  1111  and the second electrode sheet  1121  in the apparatus  1   a  for manufacturing unit cells. 
     The first electrode reel  111  is a reel on which the first electrode sheet  1111  is wound, and the first electrode sheet  1111  is unwound from the first electrode reel  111 . Also, the second electrode reel  112  is a reel on which the second electrode sheet  1121  is wound, and the second electrode sheet  1121  is unwound from the second electrode reel  112 . A plurality of first electrodes  1112  are formed by cutting the first electrode sheet  1111 , and a plurality of second electrodes  1122  are formed by cutting the second electrode sheet  1121 . 
     As illustrated in  FIG.  4   , according to another embodiment of the present invention, the first electrode sheet  1111  is unwound from the first electrode reel  111 . The first electrode sheet  1111  is cut by a first cutter  171 , and the first electrode  1112  is formed. Then, the first electrode  1112  is placed on a first conveyor  31 , and a third vision sensor  193  disposed above the first conveyor  31  captures an image of the first electrode  1112 . Also, the second electrode sheet  1121  is unwound from the second electrode reel  112 . The second electrode sheet  1121  is cut by a second cutter  172 , and the second electrode  1122  is formed. Then, the second electrode  1122  is placed on a second conveyor  32 , and a fourth vision sensor  194  disposed above the second conveyor  32  captures an image of the second electrode  1122 . Thus, before the electrodes adhere to the headers, it may be easily identified whether or not the first electrode  1112  and the second electrode  1122  have defects or are damaged with regard to the sizes, shapes, positions, or the like. 
     Those with ordinary skill in the technical field to which the present invention pertains will understand that the present invention may be implemented in other specific forms without changing the technical idea or essential features. Therefore, the above-described embodiments are to be considered illustrative and not restrictive to all aspects. The scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and various modifications derived from the meaning and scope of the claims and the equivalent concepts thereof should be interpreted as being included in the scope of the present invention. 
     
       
         
           
               
             
               
                   
               
               
                 [Description of the Symbols] 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 1: Apparatus for manufacturing unit cells 
                 2: Unit cell 
               
               
                 16: Heating roller 
                 17: Cutter 
               
               
                 18: Magazine 
                 21: First stack 
               
               
                 22: Second stack 
                 31: First conveyor 
               
               
                 32: Second conveyor 
                 111: First electrode reel 
               
               
                 112: Second electrode reel 
                 1111: First electrode sheet 
               
               
                 1121: Second electrode sheet 
                 1112: First electrode 
               
               
                 1122: Second electrode 
                 121: Lower separator reel 
               
               
                 122: Upper separator reel 
                 1211: Lower separator sheet 
               
               
                 1221: Upper separator sheet 
                 131: First feeding roller 
               
               
                 132: Second feeding roller 
                 141: First header 
               
               
                 142: Second header 
                 151: First nip roller 
               
               
                 152: Second nip roller 
                 171: First cutter 
               
               
                 172: Second cutter 
                 191: First vision sensor 
               
               
                 192: Second vision sensor 
                 193: Third vision sensor 
               
               
                 194: Fourth vision sensor 
                 311: First electrode magazine 
               
               
                 321: Second electrode magazine