Patent Publication Number: US-2023163341-A1

Title: Electrode Manufacturing Apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a national phase entry under 35 U.S.C. § 371 of the International Application No. PCT/KR2021/016674 filed on Nov. 15, 2021, which claims priority from Korean Patent Application No. 10-2020-0184478 filed on Dec. 28, 2020, the disclosures of which are incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure relates to an electrode manufacturing apparatus, and more particularly, to an electrode manufacturing apparatus that prevents breakage of an electrode. 
     BACKGROUND OF THE INVENTION 
     Along with the technology development and increased demand for mobile devices, demand for secondary batteries has also been rapidly increased. Among the secondary batteries, lithium secondary batteries having high energy density and operating voltage and excellent preservation and lifetime characteristics have been widely used as energy sources of various electronic products as well as various mobile devices. 
     The secondary battery can be formed by inserting an electrode assembly composed of a positive electrode plate, a negative electrode plate, and a separator into a case, and then sealing the case. A positive electrode plate or a negative electrode plate (hereinafter, referred to as “electrode substrate”) can be configured by coating an active material slurry onto a positive conductive current collector or a negative conductive current collector to a predetermined thickness, interposing a separator between the positive electrode conductive current collector and the negative electrode conductive current collector, and winding the plate in a jelly-roll type many times or laminating it in a plurality of layers to form an electrode assembly. 
     The electrode substrate may be formed of an active material coating portion coated with an active material slurry and an uncoated portion not coated with an active material slurry. The active material coating portion can include a rolling process for increasing the adhesiveness to the electrode current collector and increasing the volume density of the active material. The rolled electrode plate can, after drying, be used by being passed through a cutter having a certain width and cut into a predetermined size. 
     The rolling process has a problem that a compression deviation occurs due to a difference in thickness between the coating portion and the uncoated portion at the time of rolling the electrode plate. Due to such a deviation, unbalanced plastic deformation of the electrode current collector may occur, thereby causing a residual stress. In particular, the tensile residual stress may cause a reduction of fatigue durability and a reduction of fracture strength of components. 
       FIG.  1    is a schematic diagram showing a rolling process using a conventional rolling apparatus.  FIG.  2    is a plan view showing an electrode plate after rolling. 
     Referring to  FIG.  1   , a roll process of rolling a coated portion  30  and an uncoated portion  40  formed on an electrode current collector  20  by a rolling roll  10  may be performed. At this time, the pressure is concentrated on the coated portion  30 , and as shown in  FIG.  2   , a difference occurs between the degree of stretching of the coated portion  30 P and the degree of stretching of the noncoated portion  40 , and wrinkles may be generated in the uncoated portion  40 . Due to the wrinkles of the uncoated portion  40  generated during rolling, process defects such as breakage of an electrode may occur in a subsequent process. In particular, while a high tensile residual stress remains at a boundary surface between the coated portion  30 P and the uncoated portion  40 , they can continuously receive weak stress due to the contraction and expansion of the electrode, and may become vulnerable to fracture. 
     It is an object of the present disclosure to provide an electrode manufacturing apparatus that prevents breakage of an electrode. 
     However, the technical problem to be solved by embodiments of the present disclosure is not limited to the above-described problems, and can be variously expanded within the scope of the technical idea included in the present disclosure. 
     According to one embodiment of the present disclosure, there is provided an electrode manufacturing apparatus that traverses an electrode substrate having a coated portion and an uncoated portion, the apparatus comprising: a traversing roller that traverses the electrode substrate, wherein the traversing roller comprises a first roller, and a second roller surrounding an outer surface of the first roller, and wherein a diameter of a central part of the second roller is larger than a diameter of one end part of the second roller. 
     The second roller may change its position in the axial direction. 
     The first roller and the second roller may be types of being separated in the axial direction. 
     The first roller has a longer axial length than the second roller, and the first roller may be exposed from the axial direction end part of the second roller. 
     A first groove portion having at least one groove is formed on the outer surface of the first roller exposed from the axial direction end part of the second roller, and at least one second groove portion may be formed in an axial direction end part of the second roller. 
     The first roller and the second roller are connected by a fastening member when the first groove portion and the second groove portion coincide with each other while the second roller change its position in the axial direction. 
     The fastening member may be a bolt coupling type. 
     The electrode substrate may include a coated portion and an uncoated portion in which a rolling process is performed. 
     The first roller is exposed from the axial direction end part of the second roller, and the end part of the second roller and the exposed first roller may form a step. 
     The electrode substrate may travel in a state where the exposed first roller corresponds to the notched tab formed on the electrode substrate. 
     The notched tab may be formed by notching a part of the uncoated portion. 
     One end part of the second roller may form a non-contact region with the electrode substrate. 
     According to embodiments of the present disclosure, the traversing roller is composed of a first roller and a second roller that are separable from each other, and the second roller, which is an external roller, can change its position, thereby controlling the electrode meandering. 
     Also, the first roller and the second roller can be connected by a fastening member, thereby minimizing loss due to replacement of parts. 
     Further, it is possible to prevent the notched tab folding phenomenon by using the traversing roller in which a step is formed. 
     In addition, a region that is not in contact with the electrode substrate can be formed by processing the end part of the second roller, which is an external roller, thereby preventing an electrode breakage phenomenon. 
     The effects of the present disclosure are not limited to the effects mentioned above and additional other effects not described above will be clearly understood from the description of the appended claims by those skilled in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram showing a rolling process using a conventional rolling apparatus; 
         FIG.  2    is a plan view showing an electrode plate after rolling; 
         FIG.  3    is a view schematically showing a guide roll device; 
         FIG.  4    is a perspective view showing the electrode rolling device of  FIG.  3   ; 
         FIG.  5    is a view schematically showing a state in which the electrode rolling device of  FIG.  4    is viewed from the side surface; 
         FIG.  6    is a perspective view showing an electrode substrate formed by the notching process section of  FIG.  3   ; 
         FIG.  7    is a view showing an electrode manufacturing apparatus according to an embodiment of the present disclosure; 
         FIG.  8    is a plan view of the electrode manufacturing apparatus of  FIG.  7    as viewed from above; 
         FIG.  9    is a perspective view showing a traversing roller according to an embodiment of the present disclosure; and 
         FIG.  10    is an enlarged view of one end part of the traversing roller of  FIG.  9   . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out them. The present disclosure may be modified in various different ways, and is not limited to the embodiments set forth herein. 
     A description of parts not related to the description will be omitted herein for clarity, and like reference numerals designate like elements throughout the description. 
     Further, in the drawings, the size and thickness of each element are arbitrarily illustrated for convenience of description, and the present disclosure is not necessarily limited to those illustrated in the drawings. In the drawings, the thickness of layers, regions, etc. are exaggerated for clarity. In the drawings, for convenience of description, the thicknesses of some layers and regions are exaggerated. 
     In addition, it will be understood that when an element such as a layer, film, region, or plate is referred to as being “on” or “above” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, it means that other intervening elements are not present. Further, the word “on” or “above” means disposed on or below a reference portion, and does not necessarily mean being disposed “on” or “above” the reference portion toward the opposite direction of gravity. 
     Further, throughout the specification, when a portion is referred to as “including” a certain component, it means that the portion can further include other components, without excluding the other components, unless otherwise stated. 
     Further, throughout the specification, when referred to as “planar”, it means when a target portion is viewed from the upper side, and when referred to as “cross-sectional”, it means when a target portion is viewed from the side of a cross section cut vertically. 
       FIG.  3    is a view schematically showing a guide roll device. 
     Referring to  FIG.  3   , the guide roll device  100  includes a feeding roll  201 , a rolling roll  109 , a notching process section  140 , a guide roll  150 , and a winding roll  202 . Specifically, the guide roll device  100  comprises a feeding roll  201  that winds the electrode substrate  250 , a rolling roll  109  in which the electrode substrate  250  is unwound from the feeding roll  201  and supplied to the guide roll device  100 , and the supplied electrode substrate  250  is rolled, a notching process section  140  that performs a notching process to form a notched tab, a guide roll  150  that traverses the electrode substrate  250 , and a winding roll  202  that rewinds the electrode substrate  250  in which the rolling process and the notching process have been completed. 
     Before rolling the electrode substrate  250  by the rolling roll  109 , the guide roll device  100  can unwind the electrode substrate  250  wound on the feeding roll  201  and coat an electrode mixture containing an active material onto an electrode current collector. 
       FIG.  4    is a perspective view showing the electrode rolling device of  FIG.  3   .  FIG.  5    is a view schematically showing a state in which the electrode rolling device of  FIG.  4    is viewed from the side surface. 
     Referring to  FIGS.  4  and  5   , the electrode substrate  250  can be rolled in a state in which the active material is coated onto the electrode current collector layer  300  to form the coated portion  400  and the uncoated portion  500 , as described above. 
     The electrode rolling device  100  includes an unwinding roller  101  that unwinds the electrode substrate  250  having a coated portion  400  having a coating material formed on the electrode current collector layer  300  and an uncoated portion  500  corresponding to a plain portion, a rewinding roller  102  that rewinds the electrode substrate  250 , a rolling roll  109  this is positioned between the unwinding roller  101  and the rewinding roller  102  and rolls the coated portion  400  and the uncoated portion  500  of the electrode substrate  250  according to the moving direction of the electrode substrate  250 . The uncoated portion  500  may refer to a region excluding the coated portion  400  formed on the electrode current collector layer  300 . 
     The unwinding roller  101  provides the electrode substrate  250 , which is an object to be rolled, to the rolling device  100 , and allows the electrode substrate  250  to move in the arrow direction D 1  of  FIG.  5    in accordance with the clockwise rotation. The electrode substrate  250  unwound by the unwinding roller  101  passes between the rolling rolls  109  while moving along the direction of the arrow. The rolling rolls  109  are respectively positioned on both sides with respect to the electrode substrate  250 , and the electrode substrate  250  that has passed between the two rolling rolls  109  is pressed. After that, the electrode substrate  250  that has passed between the two rolling rolls  109  is wound on the rewinding roller  102  again. 
     In  FIGS.  4  and  5   , the electrode substrate  250  passing through the rolling roll  109  has been described as being disposed between the unwinding roller  101  and the rewinding roller  102 . However, in order to ensure that the electrode manufacturing process proceeds continuously by the roll-to-roll method as shown in  FIG.  3   , the electrode substrate  250  supplied from the feeding roll  201  can travel without the unwinding roller  101  and the rewinding roller  102 , and pass through the rolling roll  109  and be wound on the winding roll  202 . 
     When the coated portion  400  and the uncoated portion  500  are rolled by the rolling roll  109 , biased tension occurs due to the difference in tension between the coated portion  400  and the uncoated portion  500 , particularly, residual stress may remain in the uncoated portion  500  or the boundary portion between the coated portion  400  and the uncoated portion  500 . 
       FIG.  6    is a perspective view showing an electrode substrate formed by the notching process section of  FIG.  3   . 
     Referring to  FIGS.  3  and  6   , the uncoated portion  500  of the electrode substrate  250  may be cut by the notching process section  140  to form a notched tab  500   p . The notched tab  500   p  may have a structure protruding from the edge portion  500   a  of the uncoated portion  500 . After the notched tab  500   p  is formed by the notching process section  140 , the electrode substrate  250  may be moved by the guide roll  150  for a subsequent process progress as described in  FIG.  3   . 
       FIG.  7    is a view showing an electrode manufacturing apparatus according to an embodiment of the present disclosure.  FIG.  8    is a plan view of the electrode manufacturing apparatus of  FIG.  7    as viewed from above. 
     Referring to  FIGS.  7  and  8   , the electrode substrate  250  on which the rolling process and the notching process have been performed may be transferred by the traversing roller  600  for a subsequent process. At this time, the residual stress accumulated due to a biased tension generated in the rolling process, etc. may remain in the uncoated portion  500 , and thus breakage of the electrode base material  250  may occur. According to the present embodiment, in order to prevent the electrode substrate  250  from breaking, the diameter of the central part of the traversing roller  600  may be designed to be larger than the diameter of one end part of the traversing roller  600 . According to the present embodiment, the non-contact region P for preventing the traversing roller  600  and the electrode substrate  250  from contacting each other in the uncoated portion  500  may be formed. For this purpose, the axial direction end part of the traversing roller  600  may have a tapered shape. 
     Next, the traversing roller  600  according to the present embodiment will be described in detail with reference to  FIGS.  9  and  10   . 
       FIG.  9    is a perspective view showing a traversing roller according to an embodiment of the present disclosure.  FIG.  10    is an enlarged view of one end part of the traversing roller of  FIG.  9   . 
     Referring to  FIGS.  9  and  10   , the traversing roller  600  included in the electrode manufacturing apparatus according to the present embodiment includes a first roller  600   a  and a second roller  600   b  surrounding the outer surface of the first roller  600   a . At this time, the axial length of the second roller  600   b  may correspond to the width of the electrode substrate  250  in a direction perpendicular to the traveling direction D 1  of the electrode substrate  250  in  FIG.  8   . According to the present embodiment, the second roller  600   b  may change its position in the axial direction. The axial direction of the second roller  600   b  may be the x-axis direction of  FIG.  9   , and may be perpendicular to the traveling direction D 1  of the electrode substrate  250 . By allowing the second roller  600   b  to change its position in the axial direction, it is possible to control meandering of the electrode substrate  250 . Further, the first roller  600   a  and the second roller  600   b  may be types that are separated in the axial direction. 
     The first roller  600   a  according to the present embodiment has a longer axial length than the second roller  600   b , and the first roller  600   a  may be exposed from the axial direction end part of the second roller  600   b . In other words, the first roller  600   a  is an inner roller, and the second roller  600   b  is an outer roller and surrounds the circumference of the first roller  600   a , and a part of the first roller  600   a  having a longer axial length than the second roller  600   b  protrudes outside the second roller  600   b.    
     The first roller  600   a  and the second roller  600   b  may be fastening members. The fastening member may have a bolt fastening structure as an example. In order to be fastened by bolts, a first groove portion  600   h   1  having at least one groove is formed on the outer surface of the first roller  600   a  exposed from the axial direction end part of the second roller  600   b , and a second groove portion  600   h   2  may be formed at an axial direction end part of the second roller  600   b . At this time, when the first groove portion  600   h   1  and the second groove portion  600   h   2  coincide with the second roller  600   b  while changing its position in the axial direction, the first roller  600   a  and the second roller  600   b  can be connected by a bolt-type coupling system. 
     According to the present embodiment, the first roller  600   a  is exposed from the axial direction end part of the second roller  600   b , and the end part of the second roller  600   b  and the exposed first roller  600   a  may form a step. Since the electrode substrate  250  travels in a state where the exposed first roller  600   a  corresponds to the notched tab  500   p  shown in  FIG.  6   , it is possible to prevent the notched tab  500   p  from being folded. 
     Further, the diameter of the central part of the second roller  600   b  may be larger than the diameter of one end part of the second roller  600   b . In this regard, as described in  FIG.  8   , the diameter of the central part of the traversing roller  600  may be designed to be larger than the diameter of one end part of the traversing roller  600 , and the diameter of the central part of the second roller  600   b  included in the traversing roller  600  is designed to be larger than the diameter of one end part of the second roller  600   b , whereby a non-contact region not in contact with the electrode substrate  250  may be formed at one end part of the second roller  600   b.    
     Although preferred embodiments of the present disclosure have been shown and described above, the scope of the present disclosure is not limited thereto, and numerous other variations and modifications made by those skilled in the art using the basic principles of the invention defined in the appended claims also fall within the spirit and scope of the invention. 
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
         
           
               109 : rolling roll 
               250 : electrode substrate 
               500   p : notched tab 
               600 : traversing roller 
               600   a : first roller 
               600   b : second roller 
               600   h   1 : first groove portion 
               600   h   2 : second groove portion