Patent Description:
The present invention relates to a lamination apparatus including a pressing roll configured such that pressing force thereof is adjustable. More particularly, the present invention relates to a lamination apparatus including a pressing roll configured such that pressing force thereof is adjustable in order to prevent non-uniform force of adhesion between electrodes constituting a bi-cell due to deviation in thickness between the electrodes.

With acceleration in capacity increase and energy density improvement of a lithium secondary battery, the lithium secondary battery has been used as an energy source for medium and large devices, such as a vehicle or a power storage system, as well as small devices, such as a portable electronic device.

The lithium secondary battery may be manufactured using a method of receiving an electrode assembly, configured to have a structure in which a positive electrode, a separator, and a negative electrode are sequentially stacked, in a battery case and hermetically sealing the battery case.

The electrode assembly includes a single-cell configured to have a structure in which a first electrode and a separator are stacked, a mono-cell configured to have a structure in which a first electrode, a separator, a second electrode, and a separator are stacked, and a bi-cell configured to have a structure in which a first electrode, a separator, a second electrode, a separator, and a third electrode are stacked.

Each of the electrodes constituting the electrode assembly is manufactured by applying an electrode mixture to one surface or opposite surfaces of a thin current collector made of copper, aluminum, or nickel and drying and pressing the same.

The electrodes thus manufactured go through the process of stacking and laminating the electrodes in the state in which a separator is interposed therebetween such that the electrodes are coupled to each other. When there occurs deviation in thickness between electrode mixture layers applied to the electrodes, however, the electrodes may be non-uniformly coupled to each other.

In connection therewith, <FIG> is a view showing a bi-cell lamination process using a conventional lamination apparatus.

Referring to <FIG>, an electrode assembly is a bi-cell configured such that a first electrode <NUM>, a separator <NUM>, a second electrode <NUM>, a separator <NUM>, and a third electrode <NUM> are sequentially stacked. The thicknesses of electrode mixture layers <NUM> applied to opposite surfaces of an electrode current collector <NUM> of the second electrode <NUM> are not uniform. The left-side thickness of each of the electrode mixture layers is small, and the right-side thickness of each of the electrode mixture layers is large.

A pair of pressing rolls <NUM> is disposed above the first electrode <NUM> and under the third electrode <NUM> to press the electrode assembly. At this time, the pressing rolls <NUM> apply uniform pressure to the entireties of the surfaces of the first electrode <NUM> and the third electrode <NUM> that abut the pressing rolls. As a result, it is difficult for the left sides of the electrode mixture layers <NUM> of the second electrode to be brought into tight contact with the left side of the first electrode <NUM> and the left side of the third electrode <NUM>.

If adhesion is not achieved at an interface between the electrodes, as described above, non-uniform degradation of the electrodes may be caused, and lithium ions have difficulty moving, whereby resistance may be increased, and therefore performance of a lithium secondary battery may be lowered.

Also, in a production process to manufacture a stacked and folded type electrode assembly, bi-cells must be disposed on a long sheet type separation film one by one, and an electrode separated from one bi-cell may be disposed together with another bi-cell.

Such a problem may occur due to poor adhesion between the first electrode and the second electrode and between the third electrode and the second electrode when the thickness of the second electrode disposed at the middle, among the electrodes constituting the bi-cell, is non-uniform.

Therefore, there is a need for technology capable of securing the force of coupling between all electrodes constituting a bi-cell when the thickness of an electrode mixture layer of the second electrode disposed at the middle, among the electrodes, is non-uniform.

<CIT> discloses an electrode assembly manufacturing apparatus comprising a thickness measurement unit measuring a thickness of one or more from an electrode and a separation film; and a lamination unit pressing the electrode and the separation film, which are laminated while passing through the thickness measurement unit, while passing the electrode and the separation film between a pair of vertically arranged pressing roll units to bond the electrode and the separation film.

<CIT> discloses a manufacturing method including a rolling step of forming an electrode composition layer on a base substrate of which the coefficient of friction with powder is settled within a predetermined range, by compression-molding the powder on the base material while using a rolling device capable of making a rotation speed of one pressing roll between a pair of pressing rolls of which the rotation axes are parallel and which are disposed substantially horizontally, different from a rotation speed of the other pressing roll; a measuring step of measuring a unit weight of the powder with respect to the base material in the rolling step; and a change step of changing a speed ratio of the rotation speed of the one pressing roll with respect to the rotation speed of the other pressing roll on the basis of a result of the measurement in the measuring step.

<CIT> discloses a fabricating method of a unit structure for accomplishing an electrode assembly formed by a stacking method, and an electrochemical cell including the same are disclosed. The fabricating method of the electrode assembly is characterized with fabricating the unit structure by conducting a first process of laminating and forming a bicell having a first electrode/separator/second electrode/separator/first electrode structure, and conducting a second process of laminating first separator/second electrode/second separator one by one on one of the first electrode among two of the first electrodes.

<CIT> discloses lamination apparatus comprising an inlet through which an electrode assembly of a web structure is introduced; a first heating unit which heats the electrode assembly; a discharge unit which discharges the thermally bonded electrode assembly; a pressing unit which has a press roll; and a second heating unit which secondarily heats and rolling-presses the primarily heated electrode assembly.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a lamination apparatus including a pressing roll configured such that pressing force thereof is adjustable in order to prevent decrease in force of adhesion between electrodes due to deviation in thickness between electrode mixture layers constituting a bi-cell and an electrode assembly manufactured using the same.

A lamination apparatus according to the present invention to accomplish the above object, which is a lamination apparatus for manufacture of an electrode assembly, includes a pressing roll configured to press electrodes constituting the electrode assembly, a rotary shaft configured to rotate the pressing roll, a pressing cylinder configured to adjust a pressing force applied to the pressing roll, and a thickness measurement sensor configured to measure the thickness of an electrode mixture layer, wherein the pressing cylinder comprises a first pressing cylinder and a second pressing cylinder coupled to opposite ends of the rotary shaft, respectively; and the lamination apparatus is configured such that a pressing force applied by the first pressing cylinder and a pressing force applied by the second pressing cylinder are different from each other.

In the lamination apparatus according to the present invention, the thickness measurement sensor may include a first thickness measurement sensor and a second thickness measurement sensor disposed at opposite ends of the electrode, respectively.

The lamination apparatus according to the present invention may further include a controller configured to control the pressing force applied by the pressing cylinder when a difference occurs between the thickness of the electrode measured by the first thickness measurement sensor and the thickness of the electrode measured by the second thickness measurement sensor.

In the lamination apparatus according to the present invention, the pressing roll may be configured to more strongly press the electrode at the position at which the thickness of the electrode is smaller when a difference occurs between the thickness of the electrode measured by the first thickness measurement sensor and the thickness of the electrode measured by the second thickness measurement sensor.

In the lamination apparatus according to the present invention, the electrode assembly may be a bi-cell having a structure in which a first electrode, a separator, a second electrode, a separator, and a third electrode are stacked.

The lamination apparatus according to the present invention may further include a first electrode supply unit, a second electrode supply unit, and a third electrode supply unit, wherein the thickness measurement sensor may measure the thickness of a second electrode supplied from the second electrode supply unit.

In the lamination apparatus according to the present invention, each of the electrodes may be a double-sided electrode having electrode mixtures coated on opposite surfaces of an electrode current collector, and the lamination apparatus may be disposed at each of an upper surface and a lower surface of the electrode.

In the lamination apparatus according to the present invention, the thickness measurement sensor may include a radiation portion configured to radiate a beta ray transmitted through the electrode and a receiving portion configured to sense the beta ray radiated by the radiation portion, and the radiation portion may be configured to be disposed at any one of the upper surface and the lower surface of the electrode while the receiving portion may be disposed at the other.

In the lamination apparatus according to the present invention, pressing forces applied to a first end and a second end of an upper pressing roll configured to be disposed at the upper surface of the electrode may be configured to be set independent of pressing forces applied to a first end and a second end of a lower pressing roll configured to be disposed at the lower surface of the electrode.

In the lamination apparatus according to the present invention, the pressing roll may be configured to be capable of being heated.

Further described herein is an electrode assembly manufactured using the lamination apparatus. Specifically, the electrode assembly may be a bi-cell having a structure in which a first electrode, a separator, a second electrode, a separator, and a third electrode are sequentially stacked, and the first electrode and the second electrode may be coupled to each other, and the second electrode and the third electrode may be coupled to each other, throughout outer peripheries thereof.

In addition, the present invention may provide various combinations of the above solving means.

As is apparent from the above description, in the present invention, it is possible to adjust pressing force of a pressing roll configured to press a bi-cell, and therefore it is possible to secure the force of adhesion between electrodes by increasing the pressing force of the pressing roll at a part of an electrode mixture layer at which the thickness thereof is small.

In addition, it is possible to measure the thickness of an electrode mixture layer of a second electrode of the bi-cell, which is located at a middle thereof, using a thickness measurement sensor, whereby it is possible to form an adhesive surface throughout an interface between a first electrode and a separator and an interface between the separator and the second electrode.

In addition, it is possible to individually adjust pressing forces applied to a pressing roll disposed above the first electrode of the bi-cell and a pressing roll disposed under a third electrode by a first pressing cylinder and a second pressing cylinder coupled to opposite ends of rotary shafts of the pressing rolls, whereby it is possible to secure the force of adhesion between the first electrode and the second electrode and between the third electrode and the second electrode even though there is deviation in thickness between electrode mixture layers formed on opposite surfaces of the second electrode.

In addition, the pressing roll is configured such that the temperature of the pressing roll can be increased, whereby it is possible to further increase the force of adhesion between the electrodes.

Since the force of adhesion between the electrodes is secured, as described above, it is possible to provide a battery cell having low resistance. In addition, non-uniform degradation of the electrode assembly is prevented, whereby it is possible to provide a battery cell having increased lifespan.

In addition, bi-cells may be disposed on a separation sheet one by one when a stacked and folded type electrode assembly is manufactured, whereby it is possible to reduce incorrect bi-cell placement, and therefore it is possible to secure productivity of the electrode assembly.

<FIG> is a front view showing the state in which a bi-cell is laminated using a lamination apparatus according to the present invention.

Referring to <FIG>, pressing rolls <NUM> are disposed above and under an electrode assembly.

The electrode assembly is a bi-cell configured such that a first electrode <NUM>, a separator <NUM>, a second electrode <NUM>, a separator <NUM>, and a third electrode <NUM> are sequentially stacked. The first electrode <NUM> and the third electrode <NUM> are electrodes having the same polarity, and the second electrode <NUM> is an electrode having a polarity different from the polarity of the first electrode <NUM> and the third electrode <NUM>.

Each of the first electrode <NUM>, the second electrode <NUM>, and the third electrode <NUM> is a double-sided electrode having electrode mixture layers applied to opposite surfaces of an electrode current collector.

The thickness of each of the electrode mixture layers <NUM> applied to the upper surface and the lower surface of the electrode current collector <NUM> of the second electrode <NUM> is not uniform. The left-side thickness of each of the electrode mixture layers is relatively small, and the right-side thickness of each of the electrode mixture layers is relatively large.

In this case, when the electrode assembly is pressed in the state in which rotary shafts <NUM> of the pressing rolls <NUM> are disposed parallel to each other, as shown in <FIG>, it is difficult to remove a gap between the first electrode <NUM> and the second electrode <NUM> and a gap between the third electrode <NUM> and the second electrode <NUM> at the left side, at which the thickness of each of the electrode mixture layers <NUM> is relatively small. As a result, non-adhered portions may occur at left parts of the first electrode <NUM> and the second electrode <NUM> and left parts of the third electrode <NUM> and the second electrode <NUM>.

In the present invention, therefore, a first pressing cylinder <NUM> and a second pressing cylinder <NUM> configured to be independently controlled are coupled to opposite ends of each of the rotary shafts <NUM>, which are configured to rotate the pressing rolls <NUM>.

Specifically, pressing force applied by the first pressing cylinder <NUM> and pressing force applied by the second pressing cylinder <NUM> are different from each other. The first pressing cylinder <NUM> is located so as to be adjacent to the part at which the thickness of each of the electrode mixture layers is relatively small, and the second pressing cylinder <NUM> is located so as to be adjacent to the part at which the thickness of each of the electrode mixture layers is relatively large.

When the pressing force applied by the first pressing cylinder <NUM> is greater than the pressing force applied by the second pressing cylinder <NUM>, the first electrode <NUM> and the third electrode <NUM> may be deeply pressed in a direction toward the second electrode <NUM>. Consequently, it is possible to completely adhere the electrodes to each other at the left part, at which the thickness of each of the electrode mixture layers <NUM> is relatively small as well as the right part, at which the thickness of each of the electrode mixture layers <NUM> is relatively large.

<FIG> is a side view showing the state in which a bi-cell is laminated using a lamination apparatus according to an embodiment, and <FIG> is a perspective view showing the state in which a controller is added to the lamination apparatus of <FIG>.

Referring to <FIG> and <FIG>, the lamination apparatus according to the present invention, which is configured to manufacture a bi-cell, includes a pressing roll <NUM> configured to press electrodes constituting an electrode assembly, a rotary shaft <NUM> configured to rotate the pressing roll <NUM>, a first pressing cylinder <NUM> and a second pressing cylinder <NUM> configured to adjust pressing force applied to the pressing roll <NUM>, and a first thickness measurement sensor <NUM> and a second thickness measurement sensor <NUM> configured to measure the thickness of one of the electrodes.

The lamination apparatus includes a first electrode supply unit configured to supply a first electrode <NUM>, a second electrode supply unit configured to supply a second electrode <NUM>, and a third electrode supply unit configured to supply a third electrode <NUM>, and the thickness measurement sensors measure the thickness of the second electrode <NUM> supplied from the second electrode supply unit.

The electrode assembly is a bi-cell configured such that the first electrode <NUM>, a separator <NUM>, the second electrode <NUM>, a separator <NUM>, and the third electrode <NUM> are sequentially stacked. The first electrode <NUM> is configured such that electrode mixture layers <NUM> are formed on opposite surfaces of an electrode current collector <NUM>, the second electrode <NUM> is configured such that electrode mixture layers <NUM> are formed on opposite surfaces of an electrode current collector <NUM>, and the third electrode <NUM> is configured such that electrode mixture layers <NUM> are formed on opposite surfaces of an electrode current collector <NUM>.

The first electrode <NUM> and the third electrode <NUM> are electrodes having the same polarity, and the second electrode <NUM> is an electrode having a polarity different from the polarity of the first electrode <NUM> and the third electrode <NUM>. That is, when the first electrode and the third electrode are positive electrodes, the second electrode is a negative electrode. When the first electrode and the third electrode are negative electrodes, the second electrode is a positive electrode.

The separator <NUM> is attached to an outer surface of the electrode mixture layer <NUM> of the first electrode <NUM> that faces the second electrode <NUM>, and the first electrode <NUM> and the separator <NUM> are cut into a unit electrode by a cutter <NUM> in a step before lamination.

The separator <NUM> is attached to an outer surface of the electrode mixture layer <NUM> of the third electrode <NUM> that faces the second electrode <NUM>, and the third electrode <NUM> and the separator <NUM> are cut into a unit electrode by a cutter <NUM> in the step before lamination.

No separator <NUM> is attached to an outer surface of the electrode mixture layer <NUM> of the second electrode <NUM>, and the second electrode <NUM> is cut into a unit electrode by a cutter <NUM> in the step before lamination.

The pressing cylinders include a first pressing cylinder <NUM> and a second pressing cylinder <NUM> coupled to opposite ends of the rotary shaft <NUM>, respectively, and the pressing cylinders may be individually controlled such that pressing forces applied to the pressing roll are different from each other.

The thickness of the electrode mixture layer <NUM> of the second electrode <NUM> may not be uniform. The first thickness measurement sensor <NUM> and the second thickness measurement sensor <NUM>, which are configured to measure the thickness of the electrode mixture layer, are disposed at opposite ends of the second electrode <NUM>, respectively. Specifically, the first thickness measurement sensor <NUM> and the second thickness measurement sensor <NUM> are disposed respectively at opposite ends of the second electrode in a y-axis direction, which is perpendicular to a movement direction x of the electrode.

In order to secure the force of adhesion between the electrodes constituting the bi-cell, the size of a gap between the first electrode and the second electrode and the size of a gap between the third electrode and the second electrode may be recognized when thickness deviation of the second electrode is recognized. Consequently, it is important to check thickness deviation of the second electrode.

Each of the first thickness measurement sensor <NUM> and the second thickness measurement sensor <NUM> may be constituted by a pair of an upper sensor located above the second electrode and a lower sensor located under the second electrode. A beta ray emitted from the lower sensor is transmitted through the second electrode and reaches the upper sensor. When the loading amount of the electrode mixture layer of the second electrode is larger, the residual amount of the beta ray that reaches the upper sensor is smaller. Consequently, it is possible to measure the thickness of the electrode mixture layer of the second electrode by the principle by which the loading amount of the electrode mixture layer is calculated based on the residual amount of the beta ray measured by the upper sensor.

When a difference occurs between the thickness of the electrode mixture layer measured by the first thickness measurement sensor <NUM> and the thickness of the electrode mixture layer measured by the second thickness measurement sensor <NUM>, a difference occurs between pressing force applied by the first pressing cylinder <NUM> and pressing force applied by the second pressing cylinder <NUM>. The pressing cylinder located at the side at which the thickness of the electrode mixture layer is smaller applies stronger pressing force to the pressing roll. As a result, the parts of the first electrode and the third electrode adjacent to the small thickness part of the electrode mixture layer of the second electrode may be more deeply pressed in a direction toward the second electrode, and therefore the force of adhesion between the first electrode and the second electrode and the force of adhesion between the third electrode and the second electrode may be increased.

In a concrete example, the lamination apparatus may include a controller <NUM> configured to control pressing forces of the first pressing cylinder <NUM> and the second pressing cylinder <NUM> based on the thicknesses of the electrode mixture layer measured by the first thickness measurement sensor <NUM> and the second thickness measurement sensor <NUM>. Consequently, it is possible to calculate values measured through the first thickness measurement sensor and the second thickness measurement sensor in real time, whereby it is possible to adjust the pressing forces of the pressing cylinders without intervention of a worker.

For example, the first thickness measurement sensor <NUM> and the second thickness measurement sensor <NUM> may be disposed above an electrode that enters the cutter <NUM>, as shown in <FIG>, or may be disposed between the cutter <NUM>, which cuts an electrode sheet into a unit electrode, and the pressing roll, as shown in <FIG>.

In another concrete example, the first thickness measurement sensor <NUM> and the second thickness measurement sensor <NUM> may be disposed at an upper surface and a lower surface of the second electrode <NUM>. Consequently, it is possible to measure the thicknesses of opposite ends of the electrode mixture layer <NUM> applied to the upper surface of the second electrode <NUM> in the y-axis direction and to measure the thicknesses of opposite ends of the electrode mixture layer <NUM> applied to the lower surface of the second electrode <NUM> in the y-axis direction.

That is, it is possible to measure deviation in thickness between the electrode mixture layers applied to the upper surface and the lower surface of the second electrode <NUM>, whereby it is possible to accurately measure the gap between the first electrode <NUM> and the second electrode <NUM> and the gap between the third electrode <NUM> and the second electrode <NUM>. The pressing forces of the first pressing cylinder <NUM> and the second pressing cylinder <NUM> of the lamination apparatus disposed at the upper surface of the second electrode <NUM> may be controlled independent of the pressing forces of the first pressing cylinder <NUM> and the second pressing cylinder <NUM> of the lamination apparatus disposed at the lower surface of the second electrode <NUM>.

Consequently, pressing forces applied to a first end and a second end of the upper pressing roll disposed at the upper surface of the second electrode <NUM> may be set independent of pressing forces applied to a first end and a second end of the lower pressing roll disposed at the lower surface of the second electrode <NUM>.

In <FIG>, the first electrode <NUM>, the second electrode <NUM>, and the third electrode <NUM> are stacked between the pressing rolls <NUM> in the state in which separators (not shown) are interposed between the respective electrodes.

In the case of <FIG>, the thickness of the electrode adjacent to the first pressing cylinder <NUM> is relatively small, whereby the pressing force of the first pressing cylinder <NUM> is greater than the pressing force of the second pressing cylinder <NUM>. Consequently, the first pressing cylinder <NUM> and the second pressing cylinder <NUM> press the pressing rolls <NUM> so as to come into tight contact with the outermost electrodes of the bi-cell, and the pressing roll <NUM> adjacent to the rotary shaft <NUM> connected to the first pressing cylinder <NUM> is strongly pressed while being moved so as to come into tighter contact with the bi-cell in a direction parallel to a z-axis.

Consequently, non-adhesion between the first electrode, the second electrode, and the third electrode in the state in which the separators are interposed therebetween does not occur.

In a concrete example, the pressing rolls <NUM> may be configured to be capable of being heated, and therefore the pressing rolls may press the bi-cell in a heated state. Consequently, it is possible to further increase the force of adhesion between the electrodes.

<FIG> is a side view showing the state in which a bi-cell is laminated using a lamination apparatus according to another embodiment, and <FIG> is a perspective view showing the state in which a controller is added to the lamination apparatus of <FIG>.

Referring to <FIG> and <FIG>, a construction including a first electrode <NUM>, a second electrode <NUM>, a third electrode <NUM>, and a separator <NUM>, which constitute a bi-cell, a pressing roll <NUM>, a rotary shaft <NUM>, a first pressing cylinder <NUM>, and a second pressing cylinder <NUM> is identical to the construction shown in <FIG> and <FIG>, and therefore, a description given with reference to <FIG> and <FIG> is equally applied thereto.

Thickness measurement sensors shown in <FIG> and <FIG> may include a first thickness measurement sensor <NUM> and a second thickness measurement sensor <NUM> disposed respectively at opposite ends of the second electrode <NUM> parallel in the y-axis direction, whereby it is possible to measure the thicknesses of an electrode mixture layer <NUM> at positions corresponding to the opposite ends of the second electrode.

The first thickness measurement sensor <NUM> and the second thickness measurement sensor <NUM> include radiation portions 383a and 384a configured to radiate a beta ray capable of being transmitted through the second electrode <NUM> and receiving portions 383b and 384b configured to sense the beta ray radiated by the radiation portions 383a and 384a, respectively. The radiation portions 383a and 384a are disposed at an upper surface of the second electrode <NUM>, and the receiving portions 383b and 384b are disposed at a lower surface of the second electrode.

Alternatively, the radiation portions and the receiving portions may be disposed at positions opposite the positions shown in the figures.

When the thickness of the second electrode is larger, the residual amount of the beta ray that reaches the receiving portions is smaller. Consequently, it is possible to measure the total thickness of the electrode mixture layers applied to the upper surface and the lower surface of the second electrode <NUM> using the first thickness measurement sensor <NUM> and the second thickness measurement sensor <NUM>.

Alternatively, laser sensors may be disposed above and under the second electrode, and reflection time of a radiated laser may be measured, whereby the thickness of the second electrode may be measured.

When the bi-cell configured such that the first electrode, the separator, the second electrode, the separator, and the third electrode are sequentially stacked is manufactured using the lamination apparatus according to the present invention, as described above, adhesion may be achieved between the first electrode and the second electrode and between the second electrode and the third electrode throughout the outer surfaces thereof.

Hereinafter, the present invention will be described with reference to an experimental example. This experimental example is provided only for easier understanding of the present invention and should not be construed as limiting the scope of the present invention.

A bi-cell was manufactured in order to check influence of pressing force applied when the bi-cell was laminated on the force of adhesion between electrodes and separators.

<FIG> is a vertical sectional view and a plan view of a bi-cell manufactured according to Experimental Example.

Referring to <FIG>, the bi-cell is configured such that a first electrode <NUM>, an upper separator <NUM>, a second electrode <NUM>, a lower separator <NUM>, and a third electrode <NUM> are sequentially stacked, wherein the first electrode <NUM> and the third electrode <NUM> are positive electrodes, and the second electrode <NUM> is a negative electrode.

On the bi-cell thus manufactured, a first test of setting the pressing force of a pressing roll for lamination to <NUM> kgf and performing lamination at <NUM> and a second test of setting the pressing force of the pressing roll to <NUM> kgf and performing lamination at <NUM> were performed.

As shown in the plan view of the bi-cell, the bi-cell was divided into three regions in plan view.

Specifically, the bi-cell was divided into a tab portion Tab, which was a part adjacent to electrode tabs, a lower portion Bottom, which was opposite the tab portion, and a middle portion M, which was located between the tab portion and the lower portion. In each region, the forces of adhesion between (A) the second electrode <NUM> and the upper separator <NUM>, (B) the second electrode <NUM> and the lower separator <NUM>, (C) the first electrode <NUM> and the upper separator <NUM>, and (D) the third electrode <NUM> and the lower separator <NUM> were measured.

In order to measure the force of adhesion at (A), the second electrode <NUM> was fixed to a horizontal plate, the first electrode <NUM> and the upper separator <NUM> were fixed to a grip type jig, and the first electrode and the upper separator were pulled vertically so as to be peeled off from the second electrode, whereby the adhesive force was measured.

In order to measure the force of adhesion at (B), the second electrode <NUM> was fixed to the horizontal plate, the third electrode <NUM> and the lower separator <NUM> were fixed to the grip type jig, and the third electrode and the lower separator were pulled vertically so as to be peeled off from the second electrode, whereby the adhesive force was measured.

In order to measure the force of adhesion at (C), the first electrode <NUM> was fixed to the horizontal plate, the upper separator <NUM> was fixed to the grip type jig, and the first electrode was pulled vertically so as to be peeled off from the upper separator, whereby the adhesive force was measured.

In order to measure the force of adhesion at (D), the third electrode <NUM> was fixed to the horizontal plate, the lower separator <NUM> was fixed to the grip type jig, and the third electrode was pulled vertically so as to be peeled off from the lower separator, whereby the adhesive force was measured.

In each of the first test and the second test, as adhesive force measurement experiment, the adhesive forces at (A) to (D) were measured twice for each of the tab portion, the lower portion, and the middle portion, and the results and average values are shown in the following table. The unit of adhesive force shown in the following table is gf/<NUM>.

A universal testing machine (UTM) manufactured by Amtek was used as an adhesive force measurement device.

Referring to the following table, it can be seen that the adhesive force measured when the pressing force is high is higher than the adhesive force measured when the pressing force is low.

Claim 1:
A lamination apparatus for manufacture of an electrode assembly, the lamination apparatus comprising:
a pressing roll configured to press electrodes constituting the electrode assembly;
a rotary shaft configured to rotate the pressing roll;
a pressing cylinder configured to adjust a pressing force applied to the pressing roll; and
a thickness measurement sensor configured to measure a thickness of an electrode mixture layer;
wherein the pressing cylinder comprises a first pressing cylinder and a second pressing cylinder coupled to opposite ends of the rotary shaft, respectively; and
the lamination apparatus is configured such that a pressing force applied by the first pressing cylinder and a pressing force applied by the second pressing cylinder are different from each other.