Patent Publication Number: US-2023163431-A1

Title: Electrode Roll Connection Automation Apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/KR2021/008587 filed on Jul. 6, 2021, and now published as WO 2022/014935 A1, which claims priority from Korean Patent Application No. 10-2020-0087017 filed on Jul. 14, 2020, all of which are hereby incorporated herein by reference in their entireties. 
    
    
     FIELD 
     The present invention relates to an electrode roll connection automation apparatus, and more particularly to an electrode roll connection automation apparatus including an electrode tab sensing unit configured to measure the distance between electrode tabs such that cutting intervals of two electrode sheets are uniformly maintained in a moving direction of the electrode sheets during a process of connecting the electrode sheets to each other. 
     BACKGROUND 
     A lithium secondary battery, which is capable of being charged and discharged, has been widely used as an energy source for wireless mobile devices or wearable devices, which are worn on bodies, and has also been used as an energy source for electric vehicles and hybrid electric vehicles presented as alternatives to existing gasoline and diesel vehicles, which cause air pollution. 
     In the lithium secondary battery, a positive electrode and a negative electrode are stacked in the state in which a separator is interposed therebetween, and lithium ions move between the positive electrode and the negative electrode, whereby the lithium secondary battery is repeatedly charged and discharged. 
     A process of manufacturing an electrode including the positive electrode and the negative electrode includes a step of coating the remaining part of an electrode sheet wound in the form of a roll, excluding parts at which electrode tabs are to be formed, with an electrode agent, a step of drying and rolling the electrode agent, a step of slitting the electrode sheet, and a step of notching the slit electrode sheet into unit electrodes. 
     An electrode manufacturing process is performed as a roll-to-roll continuous process. In the case in which an electrode roll wound in the form of a roll is completely consumed while electrodes are continuously manufactured using the electrode roll, a worker stops equipment, connects a tip of the electrode roll that is being used and a tip of a new electrode roll to each other using a tape, and reoperates the equipment. 
     When the tip of the electrode roll that is being used and the tip of the new electrode roll are connected to each other using the tape, however, a difference in width between electrode tabs may occur. Such a difference may increase in the case in which skill of the worker is low. 
     In addition, when an electrode sheet is cut at a uniform speed to manufacture unit electrodes while the electrode sheet is transferred at the uniform speed, the cutting position is changed when the electrode sheet is cut into the unit electrodes if the difference in width between electrode tabs occurs, whereby defective electrodes are produced. 
     In connection therewith, Patent Document 1 discloses an electrode production system including a member configured to automatically perform replacement of an electrode material mounted to one of a plurality of electrode material supply reels to an electrode material mounted with another electrode material supply reel but does not disclose technology capable of connecting the electrode materials to each other while uniformly maintaining the distance between electrode tabs. 
     Patent Document 2 relates to an electrode sheet cutting apparatus including a sensing unit configured to sense a notching recess of an electrode sheet and to generate a notching recess sensing signal and a cutting unit configured to cut the portion of the electrode sheet at which the notching recess is located when passing through a cutting point in response to the notching recess sensing signal generated by the sensing unit and a cutting method. 
     However, Patent Document 2 neither teaches nor discloses a method of connecting two electrode sheets to each other such that the width of electrode tabs is uniform and an apparatus related thereto. 
     In addition, Patent Document 3 discloses an automatic electrode film replacement apparatus but does not disclose technology for checking the distance between electrode tabs when electrode films are connected to each other. 
     Therefore, there is a high necessity for technology capable of connecting electrode sheets so as to have uniform quality irrespective of skill of a worker and uniformly maintaining the width of electrode tabs, whereby it is possible to prevent occurrence of defects at the time of cutting the electrode sheets into unit electrodes. 
     PRIOR ART DOCUMENT 
     (Patent Document 1) Korean Registered Patent Publication No. 10-1857396 (2018 Mary 11) 
     (Patent Document 2) Korean Patent Application Publication No. 2019-0127283 (2019 Nov. 13) 
     (Patent Document 3) Korean Patent Application Publication No. 2016-0133264 (2016 Nov. 22) 
     SUMMARY OF THE DISCLOSURE 
     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 roll connection automation apparatus capable of maintaining the width of electrode tabs so as to have a uniform size when electrode sheets are connected to each other, whereby it is possible to prevent occurrence of defects at the time of electrode cutting, and continuously supplying electrode rolls without interruption in an electrode manufacturing process. 
     In order to accomplish the above object, an electrode roll connection automation apparatus according to the present invention includes a first supply unit configured to supply a first electrode sheet having electrode tabs formed thereon, a second supply unit configured to supply a second electrode sheet having electrode tabs formed thereon, a connection unit configured to connect the first electrode sheet and the second electrode sheet to each other, and an electrode tab sensing unit disposed between the first supply unit and the connection unit, the electrode tab sensing unit being configured to measure the distance between the electrode tabs. 
     In the electrode roll connection automation apparatus according to the present invention, the second supply unit may be configured to have a structure in which the second supply unit is unwound in order to supply the second electrode sheet so as to be connected to the first electrode sheet and in which the second supply unit is rewound in order to rewind the first electrode sheet and the second electrode sheet after the first electrode sheet and the second electrode sheet are connected to each other. 
     In the electrode roll connection automation apparatus according to the present invention, the electrode tab sensing unit may include a transmitter configured to transmit a signal and a receiver configured to receive the signal, the transmitter and the receiver being disposed so as to face each other, and the electrode tab sensing unit may measure the distance between the electrode tabs of the first electrode sheet while the electrode tabs pass between the transmitter and the receiver. 
     In the electrode roll connection automation apparatus according to the present invention, the connection unit may include a cutter configured to cut a tip of a start portion of the first electrode sheet such that the distance between the electrode tabs measured by the electrode tab sensing unit is maintained when the first electrode sheet and the second electrode sheet are connected to each other. 
     The electrode roll connection automation apparatus according to the present invention may further include a tape attachment unit configured to connect the first electrode sheet and the second electrode sheet to each other. 
     In the electrode roll connection automation apparatus according to the present invention, a recess may be formed in an outer edge of the first electrode sheet at which no electrode tabs are formed, which is one of opposite side outer edges of the first electrode sheet in a moving direction thereof, and the electrode roll connection automation apparatus may further include an edge position control (EPC) sensor configured to sense the position of the recess. 
     In addition, the moving direction of the first electrode sheet or the second electrode sheet may be adjusted in response to sensing of the EPC sensor. 
     The present invention provides an automatic electrode roll connection method using the electrode roll connection automation apparatus. Specifically, the automatic electrode roll connection method includes (a) unwinding a first electrode sheet, (b) measuring the distance between electrode tabs while the first electrode sheet passes through the electrode tab sensing unit, (c) cutting a tip of a start portion of the first electrode sheet based on the distance between the electrode tabs, and (d) connecting the first electrode sheet and a second electrode sheet to each other. 
     In the automatic electrode roll connection method according to the present invention, step (b) may be performed using a sensor capable of measuring the distance between the electrode tabs. 
     In the automatic electrode roll connection method according to the present invention, step (b) may be performed together with a process of sensing the position of a recess of the first electrode sheet. 
     In addition, the present invention provides electrode sheets connected to each other using the electrode roll connection automation apparatus, wherein the width of a unit electrode formed at connection portions of the first electrode sheet and the second electrode sheet is equal to the width of a unit electrode of the first electrode sheet and the width of a unit electrode of the second electrode sheet. 
     As is apparent from the above description, an electrode roll connection automation apparatus according to the present invention is configured such that a process of connecting electrode sheets to each other is automatically performed, whereby it is possible to connect the electrode sheets to each other so as to have uniform quality irrespective of skill of a worker. 
     In addition, since an electrode tab sensing unit is included, it is possible to connect the electrode sheets to each other such that the width of electrode tabs is uniformly maintained. 
     In addition, since an EPC sensor is used, it is possible to connect a first electrode sheet and a second electrode sheet to each other such that the first electrode sheet and the second electrode sheet are uniformly aligned in a moving direction thereof. 
     Consequently, it is possible to prevent manufacture of defective unit electrodes due to a difference in width between the electrode tabs during a cutting process for manufacturing unit electrodes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of an electrode roll connection automation apparatus according to an embodiment. 
         FIG.  2    is a perspective view showing a process in which a first electrode sheet shown in  FIG.  1    is cut using the electrode roll connection automation apparatus of  FIG.  1    after passing through an electrode tab sensing unit. 
         FIG.  3    is a perspective view showing the electrode roll connection automation apparatus of  FIG.  1    with an EPC sensor in accordance with another embodiment. 
         FIG.  4    is a plan view showing the portion at which the first electrode sheet and a second electrode sheet both shown in  FIG.  1    are connected to each other. 
         FIG.  5    is a perspective view showing a process of connecting the first electrode sheet and the second electrode sheet to each other using a tape attachment unit in accordance with another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     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 rather 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. 
     In addition, all numeric ranges include the lowest value, the highest value, and all intermediate values therebetween unless the context clearly indicates otherwise. 
     Embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       FIG.  1    is a perspective view of an electrode roll connection automation apparatus according to an embodiment. 
     Referring to  FIG.  1   , the electrode roll connection automation apparatus includes a first supply unit configured to supply a first electrode sheet  110  having electrode tabs  101  formed thereon, a second supply unit configured to supply a second electrode sheet  120  having electrode tabs  101  formed thereon, a connection unit  200  configured to connect the first electrode sheet  110  and the second electrode sheet  120  to each other, and an electrode tab sensing unit  300  disposed between the first supply unit and the connection unit  200 , the electrode tab sensing unit  300  being configured to measure the distance between the electrode tabs  101 . 
     When the second electrode sheet, which is a moving electrode, is completely consumed during an electrode manufacturing process performed as a roll-to-roll continuous process, it is necessary to perform a process of connecting the first electrode sheet, which is a standby electrode, to a tip of the second electrode sheet. 
     For the electrode sheet having the electrode tabs formed thereon, a difference in width between the electrode tabs may occur depending on the position of connection portions of the moving electrode and the standby electrode. If the difference in width between the electrode tabs occurs, a cutting position may be changed during a process of cutting the electrode sheet into unit electrodes, whereby a plurality of defective electrodes may be formed. 
     Therefore, the distance between the electrode tabs of the first electrode sheet is measured before the first electrode sheet and the second electrode sheet are connected to each other such that the distance between the electrode tabs is uniform when the first electrode sheet and the second electrode sheet are connected to each other. The distance between the electrode tabs is measured through a process in which the electrode tabs of the first electrode sheet pass through the electrode tab sensing unit  300 . Measurement of the distance between the electrode tabs will be described in detail below. 
     The cutting position of a tip of a start portion of the first electrode sheet may be accurately calculated based on the distance between the electrode tabs measured as described above. The tip of the start portion of the first electrode sheet may be cut based on a value calculated as described above. 
     At this time, the portion of the first electrode sheet to be cut is determined in consideration of the position of a tip of an end portion of the second electrode sheet. Preferably, the tip of the end portion of the second electrode sheet is cut such that an electrode tab is disposed at a connection portion of the second electrode sheet. The end portion of the second electrode sheet may be cut to form the connection portion of the second electrode sheet such that the width of the electrode tab formed at the connection portion of the second electrode sheet is 50% of the width of the other electrode tabs. 
     Consequently, a connection portion of the first electrode sheet is formed at the tip of the start portion of the first electrode sheet such that an electrode tab having a size equal to 50% of the width of the other electrode tabs, and the electrode tab formed at the connection portion of the first electrode sheet and the electrode tab formed at the connection portion of the second electrode sheet are connected to each other by butt welding, whereby an electrode tab having a width equal to the width of the other electrode tabs may be formed. 
     As described above, the first electrode sheet and the second electrode sheet are connected to each other in the state in which the connection portion of the second electrode sheet and the connection portion of the first electrode sheet are disposed so as not to overlap each other, whereby the electrode sheets may be connected to each other such that width of the electrode tabs and the distance between the electrode tabs are uniformly maintained. 
     As described above, the first electrode sheet and the second electrode sheet may be connected to each other such that the distance between the electrode tabs is uniformly maintained. Consequently, the cutting interval is uniformly maintained during a process of cutting the connected electrode sheets into unit electrodes. Consequently, it is possible to prevent occurrence of a problem in that defective electrodes are formed due to deviation of the cutting position at which the electrode sheet is cut into unit electrodes in the case in which the distance between the electrode tabs is changed in a conventional process of connecting the moving electrode and the standby electrode. 
     In the first supply unit shown in  FIG.  1   , a first roller  111  is unwound in order to withdraw the first electrode sheet  110 , and a plurality of transfer rollers  103  is disposed at the lower surface of the first electrode sheet  110  to transfer the first electrode sheet  110  in an x-axis direction. 
     Alternatively, a gripper may transfer the first electrode sheet  110  in a state of gripping opposite side tips of the first electrode sheet. 
     The second supply unit is configured to have a structure in which a second roller  121  is unwound in order to supply the second electrode sheet  120  so as to be connected to the first electrode sheet  110  and in which the second roller  121  is rewound in order to rewind the first electrode sheet  110  and the second electrode sheet  120  after the first electrode sheet and the second electrode sheet are connected to each other. 
     In the electrode tab sensing unit  300 , a transmitter  310  configured to transmit a signal and a receiver  320  configured to receive the signal are disposed so as to face each other, and the distance between the electrode tabs  101  of the first electrode sheet  110  is measured while the electrode tabs  101  pass between the transmitter  310  and the receiver  320 . 
     In a concrete example, when the transmitter  310  transmits light or a wavelength toward the receiver  320 , the light or the wavelength is reflected or blocked by the electrode tab  101  while the electrode tab  101  passes between the transmitter  310  and the receiver  320 , whereby the light or the wavelength does not reach the receiver. When the portion of the first electrode sheet at which no electrode tab is formed passes between the transmitter  310  and the receiver  320 , on the other hand, the light or the wavelength may reach the receiver. 
     The time for which the light or the wavelength transmitted by the transmitter reaches or does not reach the receiver may be calculated together with the moving speed of the first electrode sheet, whereby the width of the electrode tab and the distance between the electrode tabs may be calculated. The first electrode sheet may be cut at the point corresponding to 50% of the width of the electrode tab based on the calculated value. Consequently, a connection portion of the first electrode sheet that is connected to the second electrode sheet may be prepared. 
     The width of the electrode tab and the distance between the electrode tabs may be calculated using the above method. 
     However, a method of the electrode tab sensing unit sensing the distance between the electrode tabs and the width of the electrode tab is not limited to the above method. 
       FIG.  2    is a perspective view showing a process in which the first electrode sheet of  FIG.  1    is cut after passing through the electrode tab sensing unit. 
     Referring to  FIG.  2   , the distance between the electrode tabs is measured while the first electrode sheet  110  passes through the electrode tab sensing unit  300 , and the tip of the start portion of the first electrode sheet  110  is attached to the connection unit  200 . 
     The connection unit  200  may fix the first electrode sheet  110  by suctioning. 
     The connection unit  200  includes a cutter  210  configured to cut the tip of the start portion of the first electrode sheet  110  such that the distance between the electrode tabs measured by the electrode tab sensing unit is maintained when the first electrode sheet  110  and the second electrode sheet are connected to each other. 
     The cutter  210  may cut the first electrode sheet  110  while moving along a slit  220  formed in the connection unit. 
     When the first electrode sheet and the second electrode sheet are connected to each other, the size of a unit electrode manufactured from the first electrode sheet and the size of a unit electrode manufactured from the second electrode sheet must be uniformly maintained. To this end, a method of measuring the distance between the electrode tabs using the electrode tab sensing unit, calculating the portion of the first electrode sheet to be cut such that the distance between the electrode tabs is uniformly maintained, and cutting the tip of the start portion of the first electrode sheet based on the calculation is used. 
     In connection therewith, the width of the electrode tab at the tip of the end portion of the second electrode sheet and the width of the electrode tab at the tip of the start portion of the first electrode sheet are cut so as to be 50% of the width of the other electrode tabs such that the distance between the electrode tabs is uniform when the first electrode sheet and the second electrode sheet are connected to each other. When the second electrode sheet and the first electrode sheet are connected to each other, therefore, the electrode tab of the connection portion of the second electrode sheet and the electrode tab of the connection portion of the first electrode sheet are connected to each other, whereby an electrode tab having a size equal to the width of the other electrode tabs may be formed. 
     Consequently, a unit electrode formed from the first electrode sheet and a unit electrode formed from the second electrode sheet may have the same pitch formed in parallel to the moving direction of the first electrode sheet and the second electrode sheet. 
     The pitch means the size of the electrode in a lateral direction, which is perpendicular to a direction in which the electrode tab protrudes. 
     Even though the electrode tab sensing unit is used, however, there is limitation in equalizing the size of the unit electrode in a z-axis direction, which is perpendicular to the moving direction of the first electrode sheet and the second electrode sheet. 
     In the electrode roll connection automation apparatus, therefore, recesses may be formed in an outer edge of the first electrode sheet at which no electrode tabs are formed, which is one of opposite side outer edges of the first electrode sheet in the moving direction thereof, and an EPC sensor configured to sense the position of the recesses may be further included. 
     In connection therewith,  FIG.  3    is a perspective view showing the electrode roll connection automation apparatus including the EPC sensor. 
     Referring to  FIG.  3   , the electrode tabs  101  are formed at a first tip, which is one of opposite tips of the first electrode sheet  110  in the moving direction thereof, and the recesses  102  are formed at a second tip. 
     The electrode tab sensing unit  300  may measure the distance between the electrode tabs in order to equalize the pitch of the unit electrode. 
     The EPC sensor  400 , which senses the position of the recess formed in the first electrode sheet  110 , may inspect whether the second tip of the first electrode sheet coincides with the second tip of the second electrode sheet when the first electrode sheet and the second electrode sheet are connected to each other. 
     In the case in which the second tips of the first electrode sheet and the second electrode sheet do not coincide with each other as the result of measurement of the EPC sensor, the connection unit that fixes the first electrode sheet may be moved in a z-axis direction to align the first electrode sheet and the second electrode sheet in the z-axis direction. At this time, it is preferable for deviation in alignment of the first electrode sheet and the second electrode sheet in the z-axis direction to be within 1 mm. 
       FIG.  4    is a plan view showing the portion at which the first electrode sheet and the second electrode sheet are connected to each other. 
     Referring to  FIG.  4   , the first electrode sheet  110  is located below, the second electrode sheet  120  is located above, and the first electrode sheet and the second electrode sheet are connected to each other via a tape  150  in a state of being disposed so as not to overlap each other. 
     The width w 2  of one of the electrode tabs connected to each other via the tape  150  is 50% of the width w 1  of the other electrode tabs that are not cut and connected. Two electrode tabs connected to each other via the tape are disposed adjacent to each other, whereby an electrode tab having the same size as the width w 1  of the other electrode tabs may be formed. 
     Consequently, the width P of the unit electrodes may be formed so as to have a uniform value. 
       FIG.  5    is a perspective view showing a process of connecting the first electrode sheet and the second electrode sheet to each other using a tape attachment unit. 
     Referring to  FIG.  5   , the tape attachment unit  500  includes a supply portion  510  configured to supply a tape, a gripper  520  configured to transfer the tape supplied by the supply portion  510  to an attachment portion  530 , and the attachment portion  530  being configured to move to the portion at which the first electrode sheet and the second electrode sheet are connected to each other in a state of fixing the tape. In addition, the gripper  520  may be provided with a tape cutter (not shown) configured to cut the tape. 
     The gripper  520  grips a tip of a tape roll, and disposes the tape such that a non-adhesive surface of the tape is located at the outer surface of the attachment portion  530 . At this time, the attachment portion  530  fixes the non-adhesive surface of the tape by suctioning. Suctioning of the attachment portion may be performed in the same manner as the suction portion of each of the first connection unit and the second connection unit. A vacuum decompression suctioning method may be used. 
     The gripper  520  returns to the position before the tape is disposed at the attachment portion  530 , and the tape withdrawn from the tape roll is cut in a state of being gripped. At this time, the tape is cut to a length necessary to be attached to the connection portions of the electrode sheets and is fixed to the attachment portion  530  by suctioning. 
     The attachment portion  530  is movable by a transfer means and may move to the connection portions of the first electrode sheet and the second electrode sheet in order to attach the tape to the connection portions. 
     An automatic electrode roll connection method using the electrode roll connection automation apparatus includes (a) a step of unwinding a first electrode sheet, (b) a step of measuring the distance between electrode tabs while the first electrode sheet passes through the electrode tab sensing unit, (c) a step of cutting a tip of a start portion of the first electrode sheet based on the distance between the electrode tabs, and (d) a step of connecting the first electrode sheet and a second electrode sheet to each other. 
     Step (b) may be performed using a sensor capable of measuring the distance between the electrode tabs. Optionally, step (b) may be performed together with a process of sensing the position of recesses of the first electrode sheet. 
     In the electrode sheets connected to each other using the automatic electrode roll connection apparatus and the automatic electrode roll connection method, the width of a unit electrode formed at the connection portions of the first electrode sheet and the second electrode sheet may be formed so as to be equal to the width of a unit electrode of the first electrode sheet and the width of a unit electrode of the second electrode sheet. 
     In an electrode manufacturing process performed as a roll-to-roll process, therefore, a process of connecting electrode sheets to each other is rapidly and accurately performed, whereby work efficiency may be remarkably improved while a defect rate may be reduced. 
     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 
       101 : Electrode tab 
       102 : Recess 
       103 : Transfer roller
   110 ,  110 ′: First electrode sheets
 
 111 : First roller
 
 120 : Second electrode sheet
 
 121 : Second roller
 
       150 : Tape 
       200 : Connection unit 
       210 : Cutter 
       220 : Slit 
       300 : Electrode tab sensing unit 
       310 : Transmitter 
       320 : Receiver 
       400 : EPC sensor
   500 : Tape attachment unit
   510 : Supply portion
 
       520 : Gripper 
       530 : Attachment portion 
     As is apparent from the above description, an electrode roll connection automation apparatus according to the present invention is configured such that a process of connecting electrode sheets to each other is automatically performed, whereby it is possible to connect the electrode sheets to each other so as to have uniform quality irrespective of skill of a worker. 
     In addition, since an electrode tab sensing unit is included, it is possible to connect the electrode sheets to each other such that the width of electrode tabs is uniformly maintained. 
     In addition, since an EPC sensor is used, it is possible to connect a first electrode sheet and a second electrode sheet to each other such that the first electrode sheet and the second electrode sheet are uniformly aligned in a moving direction thereof. 
     Consequently, it is possible to prevent manufacture of defective unit electrodes due to a difference in width between the electrode tabs during a cutting process for manufacturing unit electrodes.