Patent Publication Number: US-2023158697-A1

Title: Electrode Cutting Device and Electrode Manufacturing Apparatus Including the Same

Description:
TECHNICAL FIELD 
     This application claims the benefit of priority to Korean Patent Application No. 2021-0013007 filed on Jan. 29, 2021, the disclosure of which is incorporated herein by reference in its entirety. 
     The present invention relates to an electrode cutting device and an electrode manufacturing apparatus including the same. More particularly, the present invention relates to an electrode cutting device capable of monitoring a gripper configured to fix an electrode sheet, thereby preventing poor electrode cutting, and an electrode manufacturing apparatus including the same. 
     BACKGROUND ART 
     With acceleration in capacity increase and energy density improvement of a lithium secondary battery, the lithium secondary battery has been used as an energy source for medium and large devices, such as a vehicle or a power storage system, as well as small devices, such as a portable electronic device. 
     The lithium secondary battery may be manufactured using a method of receiving an electrode assembly, configured to have a structure in which a positive electrode, a separator, and a negative electrode are sequentially stacked, in a battery case and hermetically sealing the battery case. 
     The electrode assembly includes a single-cell configured to have a structure in which a first electrode and a separator are stacked, a mono-cell configured to have a structure in which a first electrode, a separator, and a second electrode are stacked, and a bi-cell configured to have a structure in which a first electrode, a separator, a second electrode, a separator, and a third electrode are stacked. 
     Each of the electrodes constituting the electrode assembly is manufactured by applying an electrode mixture to one surface or opposite surfaces of a thin electrode sheet made of copper, aluminum, or nickel, drying the same, pressing the same, and cutting the electrode sheet into a unit electrode. 
     A positive electrode and a negative electrode, each of which is the unit electrode thus manufactured, are stacked and laminated in the state in which a separator is interposed therebetween, whereby a unit cell is manufactured. 
     If the positive electrode and the negative electrode are not cut so as to have uniform sizes in a process of cutting the electrode sheet into the unit electrode, peripheries of the positive electrode and the negative electrode stacked in the state in which the separator is interposed therebetween may not be parallel to each other. 
     In addition, if poor cutting occurs when a certain unit electrode is cut from the electrode sheet, continuous poor electrode cutting may occur. In this case, it is necessary for a worker to interrupt the electrode cutting process and to take a measure for correction of poor cutting. 
     Such poor cutting may occur when air leaks from a cylinder that drives a gripper configured to fix the electrode sheet, whereby pressing force of the gripper is reduced. Conventionally, a method of checking air leakage through worker’s touch was used. 
     This method increases dead time during a battery manufacturing process, whereby yield is reduced. 
     In connection therewith, Patent Document 1 discloses an electrode cutting device configured to form an electrode tab, wherein the electrode cutting device includes a first cutting unit and a second cutting unit configured to move while crossing each other in order to cut a tab formation portion. 
     Patent Document 1 discloses that the first cutting unit disposed under the tab formation portion moves upwards, a stripper disposed above the tab formation portion moves downwards so as to come into tight contact with an upper surface of the tab formation portion, and the second cutting unit moves downwards, wherein the cutting units cross each other to form an electrode tab, but does not disclose technology for adjusting the force of the stripper that fixes the electrode tab. 
     Accordingly, there is a need for technology capable of easily checking the pressing force of a gripper configured to fix an electrode sheet when cutting the electrode sheet into a unit electrode, thereby preventing poor electrode cutting. 
     (Prior Art Document) 
     (Patent Document 1) Korean Registered Patent Publication No. 1751008 (2017.06.20) 
     DISCLOSURE 
     Technical Problem 
     The present invention has been made in view of the above problems, and it is an object of the present invention to provide an electrode cutting device capable of stably fixing an electrode sheet such that electrodes stacked in a lamination process are aligned with each other and an electrode manufacturing apparatus including the same. 
     TECHNICAL SOLUTION 
     An electrode cutting device according to the present invention to accomplish the above object includes a cutting unit configured to cut an electrode sheet and a fixing unit configured to fix the electrode sheet, wherein the cutting unit includes a cutter configured to cut the electrode sheet by shearing and a cutter lifting portion configured to move the cutter so as to be perpendicular to a surface of the electrode sheet, and the fixing unit includes a gripper configured to press the electrode sheet so as to be fixed, a driving portion configured to drive the gripper so as to be moved, and a sensor configured to monitor the driving portion 
     In the electrode cutting device according to the present invention, the cutter may be configured to have a double-edged structure in which the height of the cutter is gradually increased from the middle to opposite ends thereof in a lateral direction. 
     In the electrode cutting device according to the present invention, the cutter may include an upper cutter located above the electrode sheet and a lower cutter located under the electrode sheet, the lower cutter being configured to cut the electrode sheet while crossing the upper cutter moved downwards. 
     In the electrode cutting device according to the present invention, the driving portion may be driven by a cylinder. 
     In the electrode cutting device according to the present invention, the width of the gripper may be greater than the width of the electrode sheet. 
     In the electrode cutting device according to the present invention, a protrusion may be formed on a pressing surface of the gripper. 
     In the electrode cutting device according to the present invention, a rubber coating layer may be added to the pressing surface of the gripper. 
     In the electrode cutting device according to the present invention, the sensor may be a pneumatic gauge sensor, and the sensor may continuously or periodically monitor the pressure of the cylinder. 
     In the electrode cutting device according to the present invention, the sensor may be detachably attached to the driving portion. 
     In addition, the present invention provides an electrode manufacturing apparatus including the electrode cutting device. Specifically, the electrode manufacturing apparatus includes the electrode cutting device, a separator supply unit configured to supply a separator, on which a cut positive electrode and a cut negative electrode will be disposed, a lamination device configured to laminate the positive electrode and the negative electrode attached to the separator, a separator cutting unit configured to cut the separator of the laminated stack, and an inspection unit configured to inspect alignment of a unit cell, and the electrode cutting device includes a positive electrode cutting device and a negative electrode cutting device. 
     In the electrode manufacturing apparatus according to the present invention, when the alignment of the unit cell inspected by the inspection unit is not correct, the pressure of the driving portion may be checked using the sensor of the positive electrode cutting device and the sensor of the negative electrode cutting device. 
     In addition, the present invention may provide various combinations of the above solving means. 
     ADVANTAGEOUS EFFECTS 
     As is apparent from the above description, an electrode cutting device according to the present invention includes a sensor capable of monitoring the pressure of a cylinder, which is a means that drives a gripper configured to fix an electrode sheet, and therefore it is possible to check whether air leaks from the cylinder without worker intervention. 
     In addition, it is possible to check the pressure of the cylinder in real time using the sensor, whereby it is possible to prevent continuous poor electrode cutting, and therefore it is possible to reduce a defect rate. 
     In addition, anti-slip treatment is performed on a lower surface of the gripper that is brought into contact with the electrode sheet, whereby it is possible to increase fixing force of the electrode sheet. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG.  1    is a side view of an electrode cutting device according to the present invention. 
         FIG.  2    is a perspective view of the electrode cutting device. 
         FIG.  3    is a side view sequentially showing a process of cutting an electrode using a cutter including an upper cutter and a lower cutter. 
         FIG.  4    is a perspective view of the cutter. 
         FIG.  5    is a perspective view of a gripper. 
         FIG.  6    is a schematic view of an electrode manufacturing apparatus. 
     
    
    
     BEST MODE 
     Now, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings such that the preferred embodiments of the present invention can be easily implemented by a person having ordinary skill in the art to which the present invention pertains. In describing the principle of operation of the preferred embodiments of the present invention in detail, however, a detailed description of known functions and configurations incorporated herein will be omitted when the same may obscure the subject matter of the present invention. 
     In addition, the same reference numbers will be used throughout the drawings to refer to parts that perform similar functions or operations. In the case in which one part is said to be connected to another part throughout the specification, not only may the one part be directly connected to the other part, but also, the one part may be indirectly connected to the other part via a further part. In addition, that a certain element is included does not mean that other elements are excluded, but means that such elements may be further included unless mentioned otherwise. 
     In addition, a description to embody elements through limitation or addition may be applied to all inventions, unless particularly restricted, and does not limit a specific invention. 
     Also, in the description of the invention and the claims of the present application, singular forms are intended to include plural forms unless mentioned otherwise. 
     Also, in the description of the invention and the claims of the present application, “or” includes “and” unless mentioned otherwise. Therefore, “including A or B” means three cases, namely, the case including A, the case including B, and the case including A and B. 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       FIG.  1    is a side view of an electrode cutting device according to the present invention, and  FIG.  2    is a perspective view of the electrode cutting device. 
     Referring to  FIGS.  1  and  2   , an electrode sheet  310  is transferred to an upper surface of a support portion  320 , and the electrode sheet  310  is fixed by a fixing unit  200 , whereby transfer of the electrode sheet is stopped. In this state, the electrode sheet  310  is cut by a cutting unit  100 , whereby an electrode  311  is discharged. 
     Electrodes  311  are disposed on a separator  330  so as to be spaced apart from each other. 
     The electrode cutting device according to the present invention includes a cutting unit  100  configured to cut an electrode sheet  310  and a fixing unit  200  configured to fix the electrode sheet  310 . 
     The cutting unit  100  includes a cutter  110  configured to cut the electrode sheet  310  by shearing while being moved downwards so as to be perpendicular to the electrode sheet and a cutter lifting portion  120  configured to move the cutter  110  so as to be perpendicular to a surface of the electrode sheet  310 . 
     The fixing unit  200  includes a gripper  210  configured to press the electrode sheet  310  so as to be fixed, a driving portion  220  configured to drive the gripper  210  so as to be moved, and a sensor  230  configured to monitor the driving portion  220 . 
     The gripper  210  is moved upwards and downwards so as to be perpendicular to the electrode sheet  310 . That is, when the gripper is moved downwards, the electrode sheet  310  is fixed onto the support portion  320 , and when the gripper  210  is moved upwards, the fixed state of the electrode sheet  310  is released, and the electrode sheet  310  is transferred. 
     Alternatively, the gripper may be moved upwards and downwards, and at the same time or subsequently may be moved forwards and rearwards in a direction parallel to a transfer direction M of the electrode sheet. 
     The driving portion  220  is driven by a cylinder, and the gripper may be driven by increasing or decreasing the air pressure of the cylinder. 
     In addition, the cutter lifting portion  120  may be driven by increasing or decreasing the air pressure of the cylinder. 
     The sensor  230  may be a pneumatic gauge sensor, and the sensor  230  may continuously monitor the pressure of the cylinder. Alternatively, measurement time may be set such that the sensor  230  can periodically monitor the pressure of the cylinder. 
     In general, the cutting unit and the fixing unit are disposed so as to be adjacent to each other, or are integrally assembled with each other. Air may leak from the cylinder due to vibration generated from the cutting unit, whereby the air pressure of the cylinder may be reduced. In this case, the force of the fixing unit applied to the electrode sheet may be lower than a predetermined value, whereby the electrode sheet may not be stably fixed, and therefore the electrode sheet may move in the movement direction thereof. 
     If the cutting unit cuts the electrode sheet in this state, poor cutting, in which deviation occurs in length of the electrode sheet in the transfer direction M thereof, may occur. As a result, misalignment between electrodes may occur when the electrodes are stacked so as to be laminated. 
     In addition, poorly cut electrodes may be continuously manufactured as long as the electrode cutting device is not stopped, whereby yield may be reduced. 
     When such poor cutting occurs, therefore, it is important to rapidly detect the same and to take an appropriate measure. 
     In the present invention, therefore, the sensor  230  configured to measure the air pressure of the driving portion  220  may be attached to the driving portion  220 , whereby it is possible to rapidly and accurately detect whether the air pressure of the driving portion is changed. 
     In the present invention, the width a1 of the gripper  210  may be greater than the width a2 of the electrode sheet in order to secure stability in fixing the electrode sheet  310 . 
     The driving portion  220  is added to each of opposite ends of the gripper  230  in a lateral direction so as to evenly press the gripper. 
     In a concrete example, the sensor  230  may be detachably attached to the driving portion  220 , and it is possible to check whether a large number of driving portions are defective using a single sensor. 
       FIG.  3    is a side view sequentially showing a process of cutting an electrode using the cutter, which includes an upper cutter and a lower cutter. 
     Referring to  FIG.  3   , a process of cutting the electrode sheet  310  using the electrode cutting device, which includes the cutting unit  100  and the fixing unit  200  including the sensor  230 , is shown. 
     However, the cutter  110  shown in  FIG.  3    includes an upper cutter  111  located above the electrode sheet  310  and a lower cutter  112  located under the electrode sheet  310 , the lower cutter being configured to cut the electrode sheet  310  while crossing the upper cutter  111  moved downwards and to discharge an electrode  311 . 
     It is preferable for the distance between the upper cutter  111  and the lower cutter  112  to be approximately 0. The left surface of the upper cutter  111  and the right surface of the lower cutter  112  are slid relative thereto, whereby the electrode sheet  310  is cut. 
       FIG.  4    is a perspective view of the cutter. 
     Referring to  FIG.  4   , the cutter  110 , which is used as an upper cutter, is configured to have a double-edged structure in which the height H of the cutter is gradually increased from the middle to opposite ends thereof in a lateral direction W. 
     Unlike this, if the height of the cutter is uniform, cutting force is reduced, and it is difficult to achieve parallelism with the lower cutter as the width of the electrode sheet is increased. As shown in  FIG.  4   , therefore, the double-edged structure is used in order to increase cutting force. 
       FIG.  5    is a perspective view of the gripper. 
     Referring to  FIG.  5   , the gripper  210  performs a function of stably fixing the electrode sheet. In order to effectively perform this function, a protrusion  240  may be formed on a pressing surface of the gripper that is brought into tight contact with the electrode sheet. Alternatively, a rubber coating layer  250  may be formed on the pressing surface of the gripper. 
       FIG.  6    is a schematic view of an electrode manufacturing apparatus. 
     Referring to  FIG.  6   , the electrode manufacturing apparatus includes a positive electrode cutting device  400  configured to cut a positive electrode sheet in order to discharge a positive electrode, a negative electrode cutting device  500  configured to cut a negative electrode sheet in order to discharge a negative electrode, a separator supply unit  600  configured to supply a separator  330 , on which the cut positive electrode  315  and the cut negative electrode  316  will be disposed, a lamination device  700  configured to laminate the positive electrode and the negative electrode attached to the separator, a separator cutting unit  800  configured to cut the separator of the laminated stack, and an inspection unit  900  configured to inspect alignment of a unit cell  350 . 
     The positive electrode cutting device  400  and the negative electrode cutting device  500  include sensors  430  and  530  configured to monitor the pressure of grippers  410  and  510 , respectively. When the positive electrode and the negative electrode of the unit cell  350  inspected by the inspection unit  900  are misaligned, the pressure of the driving portion may be checked using the sensor  430  of the positive electrode cutting device  400  and the sensor  530  of the negative electrode cutting device  500 . 
     If the pressure of the driving portion deviates from a predetermined range, an electrode manufacturing process may be immediately interrupted in order to stop production of defective electrodes. 
     In the present invention, as described above, the sensor configured to monitor the pressure of the cylinder, which drives the gripper, is included such that the electrode sheet is cut in the state in which the electrode sheet is stably fixed, whereby it is possible to rapidly and accurately check whether defective electrodes are produced without worker intervention. 
     Those skilled in the art to which the present invention pertains will appreciate that various applications and modifications are possible within the category of the present invention based on the above description. 
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
           100 : Cutting unit 
           110 : Cutter 
           111 : Upper cutter 
           112 : Lower cutter 
           120 : Cutter lifting portion 
           200 : Fixing unit 
           210 ,  410 ,  510 : Grippers 
           220 : Driving portion 
           230 ,  430 ,  530 : Sensors 
           240 : Protrusion 
           250 : Rubber coating layer 
           310 : Electrode sheet 
           311 : Electrode 
           315 : Positive electrode 
           316 : Negative electrode 
           320 : Support portion 
           330 : Separator 
           350 : Unit cell 
           400 : Positive electrode cutting device 
           500 : Negative electrode cutting device 
           600 : Separator supply unit 
           700 : Lamination device 
           800 : Separator cutting unit 
           900 : Inspection unit 
       
    
     INDUSTRIAL APPLICABILITY 
     As is apparent from the above description, an electrode cutting device according to the present invention includes a sensor capable of monitoring the pressure of a cylinder, which is a means that drives a gripper configured to fix an electrode sheet, and therefore it is possible to check whether air leaks from the cylinder without worker intervention. 
     In addition, it is possible to check the pressure of the cylinder in real time using the sensor, whereby it is possible to prevent continuous poor electrode cutting, and therefore it is possible to reduce a defect rate. 
     In addition, anti-slip treatment is performed on a lower surface of the gripper that is brought into contact with the electrode sheet, whereby it is possible to increase fixing force of the electrode sheet.