Patent Publication Number: US-2023142281-A1

Title: Method for Manufacturing Secondary Battery and Apparatus for Manufacturing Secondary Battery

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a national stage entry under 35 U.S.C. § 371 of International Application No. PCT/KR2020/013452, filed on Oct. 5, 2020, which claims priority from Korean Patent Application No. 10-2019-0124207, filed on Oct. 7, 2019, the disclosures of which are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a method for manufacturing a secondary battery and an apparatus for manufacturing a secondary battery. 
     BACKGROUND ART 
     Secondary batteries are rechargeable unlike primarily batteries, and also, the possibility of compact size and high capacity is high. Thus, recently, many studies on secondary batteries are being carried out. As technology development and demands for mobile devices increase, the demands for secondary batteries as energy sources are rapidly increasing. 
     Rechargeable batteries are classified into coin type batteries, cylindrical type batteries, prismatic type batteries, and pouch type batteries according to a shape of a battery case. In such a secondary battery, an electrode assembly mounted in a battery case is a chargeable and dischargeable power generating device having a structure in which an electrode and a separator are stacked. 
     The electrode assembly may be approximately classified into a jelly-roll type electrode assembly in which a separator is interposed between a positive electrode and a negative electrode, each of which is provided as the form of a sheet coated with an active material, and then, the positive electrode, the separator, and the negative electrode are wound, a stacked type electrode assembly in which a plurality of positive and negative electrodes with a separator therebetween are sequentially stacked, and a stack/folding type electrode assembly in which stacked type unit cells are wound together with a separation film having a long length. 
     In the case of the stack/folding type electrode assembly according to the related art, it is difficult to adjust unit cells to be disposed spaced a certain distance from each other on the separation film. For example, bicells are seated on the separation film through a gripper, and winding is performed after adjusting a gap between the bicells. However, it is limited to adjust the bicells to be spaced a desired gap from each other by the gripper. 
     If a distance between the unit cells disposed on the separation film in an unfolded state is not uniform, a position error in which the laminated unit cells vertically disposed when the unit cells are laminated are mutually misaligned may occur to cause a problem in which extraction due to non-charging or overcharging at each misaligned overhang portion occurs. 
     [Prior Art Document] : (Patent Document) Korean Patent Publication No. 10-2014-0015647 
     DISCLOSURE OF THE INVENTION 
     Technical Problem 
     One aspect of the present invention is to provide a method for manufacturing a secondary battery and an apparatus for manufacturing a secondary battery, through which unit cells are disposed spaced a set gap value from each other on a separation sheet that is in the unfolded state when the secondary battery is manufactured. 
     Technical Solution 
     A method for manufacturing a secondary battery, in which a plurality of unit cells are seated on a separator sheet and folded to manufacture a folded cell, according to an embodiment of the present invention comprises: a supply step of allowing the plurality of unit cells to move through a moving unit so as to supply the unit cells toward the separator sheet; and a seating step of allowing the plurality of unit cells to sequentially drop onto a top surface of the separator sheet, wherein the unit cells are seated on the separator sheet so that the unit cells are spaced a set gap value from each other. 
     An apparatus for manufacturing a secondary battery, in which a plurality of unit cells are seated on a separator sheet and folded to manufacture a folded cell, according to an embodiment of the present invention comprises: a moving unit configured to allow the plurality of unit cells to move so as to supply the unit cells toward the separator sheet; and a support part configured to allow the plurality of unit cells to sequentially drop onto a top surface of the separator sheet, wherein the unit cells are seated on the separator sheet so that the unit cells are spaced a set gap value from each other. 
     Advantageous Effects 
     According to the present invention, when the secondary battery is manufactured, the unit cells may drop onto the separator sheet that is in the unfolded state so that the unit cells are disposed spaced the set gap value from each other on the separator sheet. Therefore, when the unit cells are folded to be stacked, the misaligned positional error between the unit cells that are disposed vertically may be prevented from occurring. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view illustrating a supply step of a method for manufacturing a secondary battery according to an embodiment of the present invention. 
         FIG.  2    is a perspective view illustrating a seating step of a method for manufacturing a secondary battery according to an embodiment of the present invention. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     The objectives, specific advantages, and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. It should be noted that the reference numerals are added to the components of the drawings in the present specification with the same numerals as possible, even if they are illustrated in other drawings. Also, the present invention may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. In the following description of the present invention, the detailed descriptions of related arts which may unnecessarily obscure the gist of the present invention will be omitted. 
       FIG.  1    is a perspective view illustrating a supply step of a method for manufacturing a secondary battery according to an embodiment of the present invention, and  FIG.  2    is a perspective view illustrating a seating step of a method for manufacturing a secondary battery according to an embodiment of the present invention. 
     Referring to  FIGS.  1  and  2   , a method for manufacturing a secondary battery according to an embodiment of the present invention comprises a supply step of supplying a plurality of unit cells  10  toward a separator sheet  20  and a seating step of seating the unit cells  10  on the separator sheet  20 . 
     In more detail, the method for manufacturing the secondary battery according to an embodiment of the present invention is a method for manufacturing a secondary battery, in which a plurality of unit cells  10  are seated on a separator sheet  20  and then folded to manufacture a folded cell. 
     Here, the folded cell is a power generation element that is chargeable and dischargeable. 
     Also, each of the unit cells  10  may have a shape in which electrodes and separators are alternately stacked. The electrodes may comprise a positive electrode and a negative electrode. Also, each of the separators separates the positive electrode from the negative electrode to electrically insulate the positive electrode from the negative electrode. Accordingly, the unit cell  10  may comprise at least one positive electrode, at least one negative electrode, and at least one separator. 
     The positive electrode may comprise a positive electrode collector and a positive electrode active material applied to the positive electrode collector. For example, the positive electrode collector may be provided as foil made of an aluminum material, and the positive electrode active material may be made of lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or a compound or mixture thereof containing at least one or more of the above-described materials. 
     The negative electrode may comprise a negative electrode collector and a negative electrode active material applied to the negative electrode collector. For example, the negative electrode collector may be provided as foil made of a copper (Cu) or nickel (Ni) material. The negative electrode active material may comprise synthetic graphite, a lithium metal, a lithium alloy, carbon, petroleum coke, activated carbon, graphite, a silicon compound, a tin compound, a titanium compound, or an alloy thereof. Here, the negative electrode active material may further comprise, for example, non-graphite-based SiO (silica) or SiC (silicon carbide). 
     The separators may be alternately stacked with respect to the positive electrode and the negative electrode, each of which is made of an insulation material. Each of the separators may be, for example, a multi-layered film produced by microporous polyethylene, polypropylene, or a combination thereof or a polymer film for solid polymer electrolytes or gel-type polymer electrolytes such as polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or polyvinylidene fluoride hexafluoropropylene copolymers. 
     Referring to  FIG.  1   , in the supply step, a plurality of unit cells  10  may move through a moving unit  110  so as to be supplied toward the separator sheet  20 . 
     Also, in the supply step, the unit cell  10  may move using a conveyor belt as the moving unit  110 . 
     The moving unit  110  may be disposed in a direction parallel to the separator sheet  20 , but may be disposed above the separator sheet  20 . 
     Also, the moving unit  110  may allow the unit cell  10  to move in the same direction as the moving direction of the separator sheet  20 . 
     Referring to  FIG.  2   , in the seating step, the plurality of unit cells  10  may sequentially drop onto a top surface of the separator sheet  20 , and also, the unit cells  10  may be seated to be spaced a set gap value from each other on the separation sheet  20 . Here, the set gap value may be a distance of a gap G between the unit cells  10 . ( FIGS.  1  and  2    illustrate perspective views of a shape in which a width of each of the unit cells  10  at a front side is wider than that of the unit cell at a rear side, but the unit cells may have the same width. That is, in the drawings, the unit cell  10  is shown like a trapezoidal shape, but may have a rectangular shape.) 
     Also, in the seating step, when the unit cell  10  drops onto the separator sheet  20 , the unit cell  10  dropping through a guide part  130  may be guided. 
     Here, in the seating step, the guide part  130  may comprise a plurality of guide bars  131  and  132 , and when the unit cell  10  drops, the plurality of guide bars  131  and  132  may guide front and rear ends of the unit cells  10  with respect to a traveling direction. 
     Here, the plurality of guide bars  131  and  132  may be disposed spaced apart from each other by a distance corresponding to the width of the unit cell  10 . 
     Also, the plurality of guide bars  131  and  132  may be formed, for example, in a square beam or a column shape. Here, a surface of each of the plurality of guide bars  131  and  132 , which face the unit cell  10 , may be formed in a shape corresponding to a side surface of the unit cell  10 . 
     In addition, in the seating step, after supporting a lower portion of the unit cell  10 , which moves through the moving unit  110 , by disposing the support part  120  at an end of the moving unit  110 , the support part  120  may move in a lateral direction with respect to the traveling direction of the unit cell  10  to release the support of the unit cell  10  so that the unit cell  10  drops. 
     Also, in the seating step, the support part  120  may comprise a support plate  121 , on which the unit cell  10  is seated, to allow only the support plate  121  to move in the lateral direction so that the unit cell  10  seated on the support plate  121  drops. Here, the support plate  121  may move to reduce friction when the support plate  121  moves, thereby preventing the unit cell  10  from moving together in the lateral direction. 
     Here, the support plate  121  may move at a high speed, and the unit cell  10  may not move in the lateral direction. 
     Also, the support plate  121  may move horizontally at a high speed so that the unit cell  10  drops while being maintained in a horizontal state. Alternatively, the support plate  121  may move in the lateral direction while being gradually inclined so that the separated unit cells  10  receive a less impact. 
     Also, for example, a height of a seating surface of the support plate  121 , on which the unit cell  10  is seated, may be the same as that of a seating surface of the moving unit, on which the unit cell  10  is seated to move, and thus, the seating surfaces may be connected to each other without a stepped portion. 
     Furthermore, in the seating step, after the separator sheet  20  moves so that the set gap value is reflected, the unit cell  10  may drop onto the separator sheet  20  in a state in which the separator sheet  20  is stopped and then may be seated on the separator sheet  20 . 
     In addition, the seating step may comprise a process of allowing an n-th unit cell  10  to drop onto the stopped separator sheet  20  so as to seat the n-th unit cell  10 , a process of allowing the separator sheet  20  to move by the set gap value and stopping the separator sheet  20  after the n-th unit cell  10  is seated, and a process of allowing an (n+1)-th unit cell  10  to drop onto the stopped separator sheet  20  so as to seat the (n+1)-th unit cell  10 . (Here, n is a natural number) 
     In more detail, in the seating step, for example, a process (a) of allowing a first unit cell  10  to drop onto the separator sheet  20  so as to seat the first unit cell  10 , a process (b) of allowing the separator sheet  20  to move by a set gap value and stopping the separator sheet  20  after seating the first unit cell  10 , and a process (c) of allowing a second unit cell  10  to drop onto the stopped separator sheet  20  so as to seat the second unit cell  10  may be repeatedly performed, and the second unit cell  10  and a third unit cell  10  may be sequentially seated on the separator sheet  20 . 
     Referring to  FIGS.  1  and  2   , in the method for manufacturing the secondary battery, which is configured as described above, when the secondary battery is manufactured, the plurality of unit cells  10  may move through the moving unit  110  toward the separator sheet  20 , and the moving unit cells  10  may drop onto the separator sheet  20  by a set gap value so that the unit cells  10  are disposed spaced the set gap value from each other on the separator sheet  20  that is in an unfolded state. Thus, when the unit cells  10  are folded to be stacked, it is possible to prevent misaligned positional errors between the vertically stacked unit cells  10  from occurring. 
     Hereinafter, an apparatus for manufacturing a secondary battery according to an embodiment of the present invention will be described. 
     Referring to  FIGS.  1  and  2   , an apparatus  100  for manufacturing a secondary battery according to an embodiment of the present invention may comprise a moving unit  110  configured to supply a plurality of unit cells  10  to a separator sheet  20  and a support part  120  configured to allow the plurality of unit cells  10  to sequentially drop onto a top surface of a separator sheet  20  and seat the unit cells  10  on the separator sheet  20  so that the unit cells  10  are disposed spaced a set gap value from each other. In addition, the apparatus  100  for manufacturing the secondary battery according to the embodiment of the present invention may further comprise a guide part  130  configured to guide the dropping unit cell  10 . 
     The apparatus  100  for manufacturing the secondary battery according to an embodiment of the present invention is an apparatus  100  for manufacturing a secondary battery, which is applied to the method for manufacturing the secondary battery according to the foregoing embodiment of the present invention. Thus, in descriptions of the apparatus  100  for manufacturing the secondary battery according to this embodiment of the present invention, contents duplicated with the method for manufacturing the secondary battery according to forgoing embodiment of the present invention will be omitted or briefly described, and also, differences therebetween will be mainly described. 
     In more detail, the apparatus  100  for manufacturing the secondary battery according to an embodiment of the present invention is an apparatus  100  for manufacturing a secondary battery, in which a plurality of unit cells  10  are seated on a separator sheet  20  and then folded to manufacture a folded cell. 
     A moving unit  110  may allow a plurality of unit cells  10  to move and then supply the unit cells  10  toward a separator sheet  20 . 
     In addition, the moving unit  110  may be provided as a conveyor belt so that the plurality of unit cells  10  move. 
     Furthermore, the moving unit  110  may be disposed in a direction parallel to the separator sheet  20 , but may be disposed above the separator sheet  20 . 
     Also, the moving unit  110  may allow the unit cell  10  to move in the same direction as the moving direction of the separator sheet  20 . 
     The support part  120  may allow the plurality of unit cells  10  to sequentially drop onto a top surface of the separator sheet  20 . Here, the unit cells  10  may be seated to be spaced a set gap value from each other on the separation sheet  20 . 
     In addition, the support part  120  may be disposed at an end of the moving unit  110  to support a lower portion of each of the unit cells moving through the moving unit  110 . Then, the support part  120  may move in a lateral direction with respect to a traveling direction of the unit cells  10  to release the support of the unit cells  10  so that each of the unit cells  10  drop. 
     Furthermore, the support part  120  may comprise a support plate  121 , on which the unit cell  10  is seated, to allow only the support plate  121  to move in the lateral direction so that the unit cell  10  seated on the support plate  121  drops. Here, the support plate  121  may move so that the support plate  121  does not move together with the unit cell  10  in the lateral direction by reducing friction when the support plate  121  moves. Here, the support part  120  may further comprise a support shaft  122  extending in a lateral direction of the support plate  121  to allow the support plate  121  to move through movement of the support shaft  122 . 
     Here, for example, a height of a seating surface of the support plate  121 , on which the unit cell  10  is seated, may correspond to a height of a seating surface of the moving unit, on which the unit cell  10  is seated to move. Also, as illustrated in  FIGS.  1  and  2   , the support plate  121  may have a shape corresponding to a size and shape of the unit cell  10 . 
     The guide part may guide the dropping unit cell  10  when the unit cell  10  drops onto the separator sheet  20 . 
     Also, the guide part  130  may comprise a plurality of guide bars  131  and  132 , and the plurality of guide bars  131  and  132  may guide front and rear ends of the unit cell  10  in a traveling direction when the unit cell  10  drops. 
     Furthermore, the guide bars  131  and  132  may be formed to extend in a vertical direction. Thus, the unit cell  10  dropping downward from an upper side may be seated on the separator sheet  20  without a positional error. 
     Here, the plurality of guide bars  131  and  132  may be disposed spaced apart from each other by a distance corresponding to the width of the unit cell  10 . 
     Also, the plurality of guide bars  131  and  132  may be formed, for example, in a square beam or a column shape. Here, a surface of each of the plurality of guide bars  131  and  132 , which face the unit cell  10 , may be formed in a shape corresponding to a side surface of the unit cell  10 . Each of the guide bars  131  and  132  may have a shape that is a width gradually narrowed as it goes down. In this case, the unit cell  10  may be accurately guided to a predetermined seating point while being easily inserted into the guide part  130 . 
     The apparatus  100  for manufacturing the secondary battery according to an embodiment of the present invention may further comprise a controller  140  configured to control movement and stop of the separator sheet  20  in the traveling direction. 
     Also, when the unit cell  10  moving through the moving unit  110  drops and is seated on the separator sheet  20 , the controller  140  controls an amount of movement of the separator sheet  20  to allow the unit cells  10  to be disposed spaced a set gap value from each other, thereby seating the unit cells on the separator sheet  20 . 
     Here, the separator sheet  20  may move, for example, through a moving unit (not shown), and the moving unit may be provided as, for example, a conveyor belt. Here, the controller  140  may control the movement of the separator sheet  20  by controlling an operation of the conveyor belt. 
     More specifically, for example, the controller  140  may control the moving unit  110  to allow a first unit cell  10  to move to be seated on the support part  120  and then stop the movement of the separator sheet  20  and also control the movement of the support part  120  to seat the first unit cell  10 , which is seated on the support part  120 , on the stopped separator sheet  20 . In addition, the controller  140  may allow the separator sheet  20  to move so that a second unit cell  10  is seated to be spaced a set gap value from the first unit cell  10  (i.e., the separator sheet moves by the set gap value), and simultaneously, the second unit cell  10  may move to be seated on the support part  120 . Thereafter, the controller  140  may stop the movement of the separator sheet  20  and then seat the second unit cell  10  on the separator sheet  20 . The above-described processes may be repeatedly performed so that a third unit cell  10 , a fourth unit cell, and the like are seated to be spaced the set gap value from each other on the separator sheet  20 . 
     For example, in the stack/folding type electrode assembly (folded cell), the gap value may be changed as an n value of the unit cell increases. That is, as the n value of the unit cell increases, the gap value may gradually increase. 
     While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the method for manufacturing the Secondary battery according to the present invention. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention. 
     Furthermore, the scope of protection of the present invention will be clarified by the appended claims. 
     DESCRIPTION OF THE SYMBOLS 
     
         
           10 : Unit cell 
           20 : Separator sheet 
           100 : Apparatus for manufacturing secondary battery 
           110 : Moving unit 
           120 : Support part 
           121 : Support plate 
           122 : Support shaft 
           130 : Guide part 
           131 ,132: Guide bar 
           140 : Controller