Patent Description:
A secondary battery is manufactured by mounting an electrode assembly in a cylindrical or prismatic case made of a metal material or a pouch case made of a laminate sheet including aluminum, injecting an electrolytic solution into the case, and hermetically sealing the case.

The electrode assembly, which has a structure in which a positive electrode and a negative electrode are stacked in the state in which a separator is interposed therebetween, is classified as a jelly-roll type electrode assembly, which is configured to have a structure in which a long sheet type positive electrode having an active material applied thereto and a long sheet type negative electrode having an active material applied thereto are wound in the state in which a separator is interposed therebetween; a stacked type electrode assembly which is configured to have a structure in which a flat positive electrode and a flat negative electrode are stacked in the state in which a separator is interposed therebetween; a stacked and folded type electrode assembly, which is configured to have a structure in which unit cells are wound in a state of being disposed on a long sheet type separator; or a laminated and stacked type electrode assembly, which is configured to have a structure in which unit cells are stacked in the state in which a separator is interposed therebetween.

In the stacked type electrode assembly, the stacked and folded type electrode assembly, or the laminated and stacked type electrode assembly, a single-sided electrode plate or a double-sided electrode plate configured such that an electrode active material is applied to one surface or opposite surfaces of a current collector is used.

In general, a method of manufacturing the electrode assembly includes a process of manufacturing an electrode sheet, a process of pressing the electrode sheet, a process of slitting the electrode sheet by a predetermined length so as to be suitable for the standards of a cell, a vacuum drying process, a process of notching an electrode tab on the electrode sheet, and a process of manufacturing an electrode assembly including the electrode sheet and a separator.

In connection therewith, <FIG> is a plan view showing a portion of a conventional electrode manufacturing process.

Referring to <FIG>, an electrode material coating portion <NUM> is formed on only a portion of the electrode sheet <NUM> excluding opposite side outer peripheries <NUM> and a middle part of the electrode sheet in a transfer direction A, and an electrode material non-coating portion <NUM> is formed on the remaining portion of the electrode sheet excluding the electrode material coating portion <NUM>.

The electrode sheet <NUM> is divided into two equal parts, i.e., two unit electrode sheets <NUM>, along a slitting line <NUM> at the middle part of the electrode sheet <NUM> in the transfer direction A.

A first side outer periphery <NUM> of the unit electrode sheet <NUM> divided along the slitting line <NUM> in the transfer direction A is notched in order to form an electrode tab <NUM>, and a second side outer periphery <NUM> of the unit electrode sheet is notched in order to form a portion to be cut for manufacture of a unit electrode. In <FIG>, the electrode tab <NUM> may be simultaneously notched when the electrode sheet is divided into two equal parts along the slitting line <NUM>.

In the specification of the present application, notching includes not only a process of cutting the electrode tab so as to fit the shape thereof but also cutting the electrode sheet into two equal parts along the slitting line. In addition, the electrode sheet and a sheet include a metal electrode sheet with or without an electrode material coating portion.

When the electrode is notched, theoretically, the electrode sheet must be cut so as to be parallel to the transfer direction of the electrode sheet and the electrode tab must be cut so as to be perpendicular thereto, as shown in the upper part of <FIG>. In the electrode sheet <NUM>, the electrode material coating portion <NUM> and the electrode material non-coating portion <NUM> are different in thickness from each other. When notching is performed, therefore, the electrode tab is not correctly cut but is cut (notched) in a retarded state, i.e., meandering defects occur (see the lower part of <FIG>).

When a step is formed at the electrode tab due to meandering defects, <NUM>) an upper layer and a lower layer are not accurately aligned with each other in a stacking process to manufacture the electrode assembly, whereby efficiency of a battery is reduced, <NUM>) a protruding portion of the electrode tab damages a separator, whereby short circuiting may occur, and <NUM>) when each electrode is rotated during manufacture of the electrode assembly, a criterion based on which the position of the electrodes is accurately controlled and the electrodes are stacked becomes ambiguous.

Patent Document <NUM> discloses a method of manufacturing an electrode plate for batteries that continuously forms a plurality of electrode plates from a belt type or hoop type electrode plate by punching using a punching press constituted by an upper press and a lower press capable of moving upwards and downwards, wherein the upper press has a punch and a shear blade mounted in the front thereof in a cutting direction, the lower press has a die having a punch hole, into which the punch is inserted, and a shear blade mounted in the front thereof in the cutting direction, when punching is performed in the state in which opposite sides of electrode plates are adjacent to each other as a common side in a longitudinal direction of the electrode plate, on the assumption that one of the opposite sides in a direction in which the electrode plates are adjacent to each other is opposite side A and the common side is side B, a corner formed by side A and side B is chamfered, and the lower press is configured such that a stepped upper part having two or more steps having a hole size increased stepwise in the punching direction is formed in the lower part of the punch hole.

Patent Document <NUM> does not disclose the construction of the notching pilot pin according to the present invention, and does not suggest a solution to the problem to be solved by the present invention, since this document relates to preventing clogging due to cut scraps of the electrode plate and increasing the lifespan of the notching punch.

Patent Document <NUM> discloses a notching apparatus for notching a continuous electrode sheet having an electrode active material applied to one surface or opposite surfaces thereof at unit electrode intervals in order to manufacture a plurality of unit electrodes from the electrode sheet, the notching apparatus including a press configured to notch the upper end and the lower end of the electrode sheet in the state in which the position of the press is fixed and two or more grippers located at the rear of the press in a direction in which the electrode sheet is supplied, the grippers being configured to hold and transfer the electrode sheet by one pitch, which is a size corresponding to a unit electrode, in response to the operation of the press, wherein, when one of the grippers holds and transfers the electrode sheet, the other grippers moves to positions for holding.

Patent Document <NUM> is characterized in that notches are formed in the electrode sheet, and the electrode sheet is supplied by one pitch by the first and second grippers and is then punched, whereby notching is performed at predetermined intervals, which, however, is not a solution to meandering defects.

Patent Document <NUM> discloses an electrode manufacturing apparatus including a notching roller, the electrode manufacturing apparatus including a transfer unit configured to continuously transfer a first electrode sheet having an electrode active material applied to a long sheet type current collector in order to notch and cut the first electrode sheet, a notching roller having a cylindrical structure, the notching roller being configured to notch one surface of the first electrode sheet by rotation in order to manufacture a second electrode sheet having one side outer periphery and the other side outer periphery continuously formed, and a cutter configured to cut the notched second electrode sheet to a length corresponding to the width of the electrode in order to manufacture a final electrode, wherein the notching roller includes a first notching portion configured to form one side outer periphery of the second electrode sheet and a second notching portion configured to form the other side outer periphery of the second electrode sheet when viewed in plan.

In Patent Document <NUM>, it is described that the notching roller is used, whereby no notching step occurs. In the case in which the roller type roller is used, however, deviation in thickness between an electrode material coating portion and an electrode material non-coating portion is continuously accumulated, whereby meandering defects may be increased, and Patent Document <NUM> does not recognize such a problem.

Patent Document <NUM> relates to a press apparatus configured to form a plurality of electrode plates of a lithium ion polymer battery used in a hybrid electric vehicle at once, wherein an upper press having a cutting means and a lower press configured to assist the upper press are installed, a thin flat electrode plate material is continuously supplied therebetween to simultaneously form a plurality of electrode plate members provided in a battery, whereby it is possible to accurately, uniformly, and continuously manufacture a plurality of electrode plates at once.

In Patent Document <NUM>, a notching portion is formed on a middle cutter blade such that punching is performed while the boundary between the electrode plate members is marked; A punching unit is configured to remove a portion of an outer periphery of the electrode sheet by notching. however, this document does not recognize a problem of meandering defects.

In a process of manufacturing electrodes in large quantities through notching, as described above, a problem of a step being formed due to meandering defects has a continuous influence on manufacture of an electrode assembly, which is a subsequent process, and the performance of a battery based thereon. However, such a problem is still not recognized, and a clear solution to such a problem has not been suggested yet.

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 shaping apparatus capable of solving a problem of a step being formed at an electrode tab that may occur during notching and an electrode shaping method using the same.

The invention is as defined by the claims.

In order to accomplish the above object, the present invention provides an electrode shaping apparatus including a sheet transfer unit configured to move an electrode sheet at a predetermined speed; a fixing unit configured to fix the electrode sheet; and a punch unit including a center punching unit configured to remove a central part of the electrode sheet and a side punching unit configured to remove a portion of an outer periphery of the electrode sheet by notching, wherein the center punching unit includes a hole punching member and a notching pilot pin.

The center punching unit includes a rectangular parallelepiped main body having a major axis in a movement direction of the electrode sheet; the hole punching member formed at a rear end of the main body in the movement direction of the electrode sheet; and the notching pilot pin formed under a front end of the main body in the movement direction of the electrode sheet. A pin punching portion is configured to punch a catching recess, in which the notching pilot pin is configured to be caught.

The main body may be formed in a rectangular parallelepiped shape having a major axis in the movement direction of the electrode sheet, and may include a main body punching surface configured to punch the electrode sheet as the lower surface of the rectangular parallelepiped.

The hole punching member may include an enlarged portion extending from the rear end of the main body in the movement direction of the electrode sheet, the width of the punching surface being increased at the enlarged portion and configured to punch the electrode sheet; a reduced portion extending from the enlarged portion, the width of the punching surface being decreased at the reduced portion along the major axis and configured to punch the electrode sheet; and a pin punching portion extending from the reduced portion, the pin punching portion configured to punch a catching recess, in which the notching pilot pin is configured to be caught, in the electrode sheet.

The section of the notching pilot pin may be any one of a circle, an arc, a wedge, a triangle, and a quadrangle.

The fixing unit may be provided in the middle thereof with a middle groove corresponding in shape to the center punching unit.

The middle groove may have a sufficient depth for the notching pilot pin to be inserted into the middle groove.

In addition, the present invention provides an electrode shaping method using the electrode shaping apparatus, the electrode shaping method including S1) transferring an electrode sheet by a predetermined length using the sheet transfer unit; S2) transferring the electrode sheet or the punch unit such that the notching pilot pin is caught in a recess formed in the electrode sheet in a previous step of punching such that the notching pilot pin is caught in the recess; S3) pressing the electrode sheet using the punch unit to punch the electrode sheet; and S4) spacing the punch unit apart from the electrode sheet.

In step S4), a distance by which the punch unit is spaced apart from the electrode sheet may be equal to or less than a distance by which at least a portion of the notching pilot pin remains inserted in the recess of the electrode sheet.

As is apparent from the above description, an electrode shaping apparatus having a notching pilot pin according to the present invention and an electrode shaping method using the same have an effect in that it is possible to solve a problem, which may occur during notching, of a step being formed at an electrode tab, compared to a conventional electrode shaping apparatus.

The present invention has an effect in that it is possible to remove meandering defects that may occur in the conventional electrode shaping apparatus, whereby <NUM>) an upper layer and a lower layer are accurately aligned with each other in a stacking process to manufacture the electrode assembly, whereby efficiency of a battery is increased, <NUM>) there is no protruding portion of the electrode tab, whereby damage to a separator and occurrence of a short circuit are prevented, and <NUM>) when each electrode is rotated during manufacture of the electrode assembly, a criterion based on which the position of the electrodes is accurately controlled and the electrodes are stacked becomes clear.

In the case in which one part is said to be connected to another part in the entire 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.

<FIG> is a perspective view of an electrode shaping apparatus according to an embodiment of the present invention, <FIG> is a perspective view and a sectional view of a center punching unit according to an embodiment of the present invention, <FIG> is a schematic view showing a coupling relationship between a notching pilot pin and a catching recess according to an embodiment of the present invention.

Referring to <FIG>, the electrode shaping apparatus according to the present invention includes a sheet transfer unit (not shown) configured to move an electrode sheet <NUM> at a predetermined speed; a fixing unit <NUM> configured to fix the electrode sheet <NUM>; and a punch unit constituted by a center punching unit <NUM> and a side punching unit (not shown) configured respectively to remove a central part of the electrode sheet and a portion of the outer periphery of the electrode sheet by notching, wherein the center punching unit <NUM> includes a hole punching member <NUM> and a notching pilot pin <NUM>.

The side punching unit is configured to perform notching into a special shape, as shown in <FIG>, or to perform notching into a common electrode tab shape, as shown in <FIG>. However, the present invention is not limited thereto.

The center punching unit <NUM> includes a rectangular parallelepiped main body <NUM> having a major axis in a movement direction A of the electrode sheet <NUM>, the hole punching member <NUM> formed at the rear end of the main body <NUM> in the movement direction A of the electrode sheet <NUM>, and the notching pilot pin <NUM> formed under the front end of the main body <NUM> in the movement direction A of the electrode sheet <NUM>.

The main body <NUM> may be formed in a rectangular parallelepiped shape having a major axis in the movement direction A of the electrode sheet <NUM>, and may include a main body punching surface <NUM> configured to punch the electrode sheet as the lower surface of the rectangular parallelepiped.

The hole punching member <NUM> may include an enlarged portion <NUM> extending from the rear end of the main body <NUM> in the movement direction A of the electrode sheet <NUM>, the width of the punching surface configured to punch the electrode sheet being increased at the enlarged portion; a reduced portion <NUM> extending from the enlarged portion <NUM>, the width of the punching surface configured to punch the electrode sheet <NUM> being decreased at the reduced portion along the major axis A; and a pin punching portion <NUM> extending from the reduced portion <NUM>, the pin punching portion <NUM> being configured to punch a catching recess <NUM>, in which the notching pilot pin <NUM> is caught, in the electrode sheet <NUM>. The catching recess <NUM> is formed in the electrode sheet <NUM> as indicated by a dotted line in <FIG>, and is formed in the electrode sheet <NUM> as indicated by a blue color in <FIG>.

The section of the notching pilot pin <NUM> may be any one of a circle, an arc, a wedge, a triangle, and a quadrangle, although the notching pilot pin is formed in a cylindrical shape as shown in <FIG>. In particular, the wedge type or triangular notching pilot pin may be connected to the reduced portion <NUM> in order not only to perform alignment in the transfer direction A of the electrode sheet <NUM> but also to perform alignment in a direction perpendicular to the transfer direction A.

The fixing unit <NUM> may be provided in the middle thereof with a middle groove <NUM> corresponding in shape to the center punching unit. The middle groove <NUM> may be formed so as to have a sufficient depth for the notching pilot pin <NUM> to be inserted thereinto.

In addition, the present invention provides an electrode shaping method using the electrode shaping apparatus, the electrode shaping method including S1) a step of transferring an electrode sheet by a predetermined length using the sheet transfer unit; S2) a step of transferring the electrode sheet or the punch unit such that the notching pilot pin is caught in a recess formed in the electrode sheet in a previous step of punching such that the notching pilot pin is caught in the recess; S3) a step of pressing the electrode sheet using the punch unit to punch the electrode sheet; and S4) a step of spacing the punch unit apart from the electrode sheet.

In step S4), the distance by which the punch unit is spaced apart from the electrode sheet is equal to or less than the distance by which at least a portion of the notching pilot pin remains inserted in the recess of the electrode sheet.

As described above, the electrode shaping apparatus having the notching pilot pin according to the present invention and the electrode shaping method using the same have an effect in that it is possible to solve a problem of a step being formed at an electrode tab that may occur during notching, compared to a conventional electrode shaping apparatus.

Claim 1:
An electrode shaping apparatus comprising:
a sheet transfer unit configured to move an electrode sheet (<NUM>) at a predetermined speed;
a fixing unit (<NUM>) configured to fix the electrode sheet (<NUM>); and
a punch unit including:
a center punching unit (<NUM>) configured to remove a central part of the electrode sheet (<NUM>); and
a side punching unit configured to remove a portion of an outer periphery (<NUM>) of the electrode sheet (<NUM>) by notching,
wherein the center punching unit (<NUM>) comprises a hole punching member (<NUM>) and a notching pilot pin (<NUM>),
wherein the center punching unit (<NUM>) comprises:
a rectangular parallelepiped main body (<NUM>) having a major axis in a movement direction of the electrode sheet (<NUM>);
the hole punching member (<NUM>) formed at a rear end of the main body (<NUM>) in the movement direction of the electrode sheet (<NUM>); and
the notching pilot pin (<NUM>) formed under a front end of the main body (<NUM>) in the movement direction of the electrode sheet (<NUM>),
wherein a pin punching portion (<NUM>) is configured to punch a catching recess (<NUM>) in the electrode sheet, in which the notching pilot pin (<NUM>) is configured to be caught.