Patent Description:
In recent years, a chargeable and dischargeable secondary battery has been widely used as an energy source for a wireless mobile device. Also, the secondary battery has attracted considerable attention as a power source for an electric vehicle (EV), a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle (Plug-In HEV), which have been proposed as solutions for air pollution or the like caused by existing gasoline and diesel vehicles using fossil fuels.

While one or several battery cells are used for each of small-sized mobile devices, a medium and large sized battery module, in which a plurality of battery cells are electrically connected, is used for medium and large sized devices due to necessity of high power and high capacity.

Since the medium and large sized battery module is desirably manufactured in possibly small size and weight, a rectangular battery or a pouch-type battery, which may be stacked with a high degree of integration and a small weight with respect to capacity, is mainly used for a battery cell (unit cell) of the medium and large sized battery module. In particular, since the pouch-type battery, which uses an aluminum laminate sheet or the like as an external member, has advantageous aspects such as a light weight, low manufacturing costs, and easy shape deformation, the pouch-type battery has been interested in recent years.

Various methods for manufacturing the above-described secondary batteries are provided. The most generally used method among the various methods is a technique for winding a positive electrode, a negative electrode, and a separator disposed therebetween to be formed into a jellyroll shape. However, since the above-described jellyroll shaped electrode assembly has a cross-sectional structure of a circular or oval shape by winding an elongate sheet in which a positive electrode and a negative electrode are densely arranged, a stress generated by expansion and contraction of the electrode when charged or discharged is accumulated inside the electrode assembly, and, when such a stress accumulation exceeds a predetermined range, deformation such as a crack is generated on the electrode assembly. Due to the above-described deformation of the electrode assembly, performance of the battery is dramatically reduced, and, due to internal short-circuit, stability of the battery is threatened.

The present disclosure provides a secondary battery electrode, which may relieve a pressure applied to a current collector to prevent the current collector from being deformed and prevent a crack from being generated while the electrode is manufactured in advance, a manufacturing method therefor, and an electrode assembly.

In accordance with a present disclosure, a secondary battery electrode includes: a current collector extending in one direction; a first active material layer provided on one surface of the current collector and including a first inclined portion and a first protruding portion; and a second active material layer provided on the other surface of the current collector and including a second inclined portion and a second protruding portion. Here, the second protruding portion is controlled in position on the second active material layer so as to be provided on a position that is not directly opposite to the first inclined portion with respect to the current collector.

The second protruding portion may be spaced a predetermined distance from the second inclined portion.

A non-coated portion, on which the first active material layer is not supplied, may be provided on one surface of the current collector.

The first inclined portion and the first protruding portion may be provided on one side of the first active material layer, and the second inclined portion and the second protruding portion may be provided on one side of the second active material layer, which is disposed in the same direction as the one side of the first active material layer.

Each of the first active material layer and the second active material layer is made of an electrode active material for a negative electrode or an electrode active material for a positive electrode.

According to the present invention, a manufacturing method for a secondary battery electrode is provided as defined in the appended set of claims, the manufacturing method includes: a process of preparing a current collector on which a first active material layer including a first inclined portion and a first protruding portion is formed on one surface thereof; a process of transferring the current collector in one direction; and a process of forming a second active material layer including a second inclined portion and a second protruding portion by applying a second active material on the other surface of the current collector. Here, in the process of forming the second active material layer, the second protruding portion is controlled in position on the second active material layer so as to be formed on a position that is not directly opposite to the first incline portion with respect to the current collector.

In the process of forming the second active material layer, the second protruding portion is spaced a predetermined distance from the second inclined portion.

A non-coated portion, on which the first active material layer is not supplied, may be formed on one surface of the current collector.

The second protruding portion is controlled in position by regulating an application pressure of the second active material layer.

The second protruding portion is controlled in position by regulating a transfer speed of the current collector.

In accordance with the present disclosure, an electrode assembly, which is manufactured by winding a positive electrode, a negative electrode, and a separator disposed therebetween, includes at least one of the positive electrode and the negative electrode including any one of the above-described electrodes for a secondary battery of claims <NUM> to <NUM>.

According to a manufacturing method, a secondary battery electrode obtainable from the method of the present invention, , and an electrode assembly obtainable from the method in accordance with an exemplary embodiment, as the protruding portion of the second active material layer is controlled in position to be formed on the position that is not directly opposite to the inclined portion of the first active material layer with respect to the current collector, the pressure applied to the current collector may be relieved to prevent the current collector from being deformed, and the crack generated while the electrode is manufactured may be prevented in advance.

Also, in accordance with the exemplary embodiment, the first active material layer and the second active material layer, which are formed on the both surfaces of the current collector, respectively, may be controlled in shape to produce a secondary battery electrode, which has a uniform thickness, and enhance the product stability, the economical feature, and the yield.

Rather, these embodiments are provided so that the present invention will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In the figures, like reference numerals refer to like elements throughout.

Various methods for manufacturing the above-described secondary batteries are provided. The most generally used method among the various methods is a technique for winding a positive electrode, a negative electrode, and a separator disposed therebetween to be formed into a jellyroll shape. Here, electrodes such as a positive electrode and a negative electrode contained in an electrode assembly of a secondary battery undergo a process of forming an electrode active material layer on a current collector. The above-described process of forming the electrode active material layer includes: a process of applying active material slurry in which electrode active material particles are sprayed in a binder solution; and a process of forming an electrode active material layer on a current collector by drying the active material slurry applied on the current collector to remove the solution and moisture existing in the active material slurry.

The active material slurry has a high viscosity coefficient due to physical characteristics thereof. Accordingly, when the electrode active material layer is formed on the current collector, an inclined portion, which is defined as a drag area, is sharply formed on an end of an application area, and a protruding portion, which is defined as a balcony area, is formed on a position spaced a predetermined distance from the inclined portion in a protruding manner.

<FIG> is a view illustrating an appearance of a general electrode for a secondary battery, and <FIG> is a state in which a pressure is applied to a current collector of the general electrode for a secondary battery. Also, <FIG> is a view illustrating a position at which a crack is generated in the current collector of the general electrode for a secondary battery, and <FIG> is a view illustrating a plastic strain of the current collector of the general electrode for a secondary battery.

Referring to <FIG>, in case of the general electrode for a secondary battery, a first active material layer <NUM> including a first inclined portion <NUM> and a first protruding portion <NUM> is provided on one surface of a current collector <NUM> extending in one direction. Also, a second active material layer <NUM> including a second inclined portion <NUM> and a second protruding portion <NUM> is provided on the other surface of the current collector <NUM>. Here, as described above, the inclined portion represents a drag area formed on an end of a coated area in a sharp manner, and the protruding portion represents a balcony area formed on a position spaced a predetermined distance from the inclined portion in a protruding manner.

In a battery having a jellyroll-type electrode assembly, a non-coated portion N, on which the first active material layer <NUM> is not supplied, is provided on one surface of the current collector <NUM> to ensure stability according to winding. However, when, as described above, the non-coated portion N, on which the first active material layer <NUM> is not supplied, is provided on the one surface of the current collector <NUM>, and the second active material layer <NUM> is provided on the other surface of the current collector <NUM>, a second protruding portion <NUM> of the second active material layer <NUM> is positioned on an area directly opposite to the first inclined portion <NUM> of the first active material layer <NUM>.

As described above, when the second protruding portion <NUM> of the second active material layer <NUM> is positioned on the area directly opposite to the first inclined portion <NUM> of the first active material layer <NUM>, as a thickness of the electrode of an area on which the second protruding portion <NUM> of the second active material layer <NUM> becomes remarkably thick, and a rolling ratio at the corresponding area increases in a local manner, deformation occurs on the current collector <NUM>. That is, as illustrated in <FIG>, although the current collector <NUM> maintains a thickness of approximately <NUM> between the first active material layer <NUM> and the second active material layer <NUM>, the current collector <NUM> has a thickness of approximately <NUM> at the area, which is directly opposite to the first inclined portion <NUM> of the first active material layer <NUM> and on which the second protruding portion <NUM> of the second active material layer <NUM> is positioned.

Also, in general, the non-coated portion N, on which the first active material layer <NUM> is not supplied, is provided by a predetermined length (a length of approximately <NUM> in <FIG>) from the end of the current collector <NUM> on the one surface of the current collector <NUM>. In this case, as illustrated in <FIG>, the thickness of the electrode including the first active material layer <NUM> and the current collector <NUM> continues to increase from a point at which the electrode length, i.e., a length from the end of the current collector, is approximately <NUM>, the non-coated portion is passed, and then the first active material layer <NUM>, which is initiated with the first inclined portion <NUM>, is provided on an area in which the second protruding portion <NUM> of the second active material layer <NUM> is positioned. Accordingly, the thickness of the electrode including the first active material layer <NUM>, the current collector <NUM>, and the second active material layer <NUM> remarkably increases at a point at which the electrode length including the non-coated portion N and a boundary of the second active material layer <NUM> is approximately <NUM> to approximately <NUM>.

Due to the above-described increase in electrode thickness, at the point of approximately <NUM> to approximately <NUM> from the end of the current collector <NUM>, i.e., in a predetermined area including the non-coated portion N and the boundary of the second active material layer <NUM>, the rolling ratio locally increases. That is, as illustrated in <FIG>, an equivalent plastic stain (PEEQ) of the current collector <NUM> remarkably increases to have a peak value of approximately <NUM> or more at a position at which the length from the end of the current collector is approximately <NUM> to approximately <NUM> due to the local increase of the rolling ratio. As a result, deformation occurs on the current collector <NUM>, and a crack, i.e., short-circuit, is generated while winding.

Thus, the electrode for a second battery, the method for manufacturing the same, and the electrode assembly in accordance with an exemplary embodiment suggest a technical feature capable of preventing the deformation of the current collector <NUM> by relieving the pressure applied to the current collector <NUM> and preventing the crack from being generated in advance while the electrode is wound in a process of manufacturing the electrode.

<FIG> is a view illustrating an appearance of an electrode for a secondary battery obtainable from a manufacturing method in accordance with an exemplary embodiment, and <FIG> is a view illustrating an appearance of an electrode for a secondary battery obtainable from the manufacturing method in accordance with another exemplary embodiment.

Referring to <FIG> and <FIG>, an electrode for a secondary battery in accordance with an exemplary embodiment includes: a current collector <NUM> extending in one direction, a first active material layer <NUM> provided on one surface of the current collector <NUM> and including a first inclined portion <NUM> and a first protruding portion <NUM>; and a second active material layer <NUM> provided on the other surface of the current collector <NUM> and including a second inclined portion <NUM> and a second protruding portion <NUM>. Here, the second protruding portion <NUM> is controlled so as to be provided on a position on the second active material layer <NUM>, which is not directly opposite to the first inclined portion <NUM> with respect to the current collector <NUM>.

Here, the first inclined portion <NUM> and the first protruding portion <NUM> are provided on one side of the first active material layer <NUM>, and the second inclined portion <NUM> and the second protruding portion <NUM> are provided on one side of the second active material layer <NUM>, which is disposed in the same direction as the one side of the first active material layer <NUM>. That is, as exemplarily illustrated in <FIG> and <FIG>, the first inclined portion <NUM> and the first protruding portion <NUM> may be provided on the left side of the first active material layer <NUM>, and the second inclined portion <NUM> and the second protruding portion <NUM> may be provided on the left side of the second active material layer <NUM>, which is the same direction as the above.

As previously described, in the battery having a jellyroll-type electrode assembly, a non-coated portion N, on which the first active material layer <NUM> is not supplied, is provided on one surface of the current collector <NUM> to ensure stability according to winding. However, when, as described above, the non-coated portion N, on which the first active material layer <NUM> is not supplied, is provided on the one surface of the current collector <NUM>, and the second active material layer <NUM> is provided on the other surface of the current collector <NUM>, a protruding portion <NUM> of the second active material layer <NUM> is positioned on an area directly opposite to the first inclined portion <NUM> of the first active material layer <NUM>. As a result, a rolling ratio locally increases, and a crack is generated. Accordingly, in the electrode for a secondary battery in accordance with an exemplary embodiment, the second protruding portion <NUM> of the second active material layer <NUM> is controlled so as to be provided on a position on the second active material layer <NUM>, which is not directly opposite to the first inclined portion <NUM> with respect to the current collector <NUM>.

Here, the non-coated portion N may be provided to have a length of approximately <NUM> to approximately <NUM> in an extension direction of the current collector <NUM>. The first inclined portion <NUM> represents a drag area provided to have a sharp shape on an end of the first active material layer <NUM>, and the second inclined portion <NUM> represents a drag area provided to have a sharp shape on an end of the second active material layer <NUM>.

As described in an exemplary embodiment, when the second protruding portion <NUM> of the second active material layer <NUM> is provided on a position that is not directly opposite to the first inclined portion <NUM> of the first active material layer <NUM> with respect to the current collector <NUM>, the end of the first active material layer <NUM>, i.e., the first inclined portion <NUM>, is not remarkably varied in thickness. That is, regarding a limitation in which the thickness of the electrode is remarkably varied by the first inclined portion <NUM> and the second protruding portion <NUM>, as the second protruding portion <NUM> is provided on a position that is not directly opposite to the first inclined portion <NUM>, the electrode thickness on the area of the first inclined portion <NUM> may be varied by only the first inclined portion <NUM>, and thus the electrode thickness may be prevented from being remarkably varied.

<FIG> is a view illustrating an appearance of the electrode for a secondary battery obtainable from a manufacturing method in accordance with an exemplary embodiment. As illustrated in <FIG>, the second protruding portion <NUM> of the second active material layer <NUM> is transferred from the position directly opposite to the inclined portion <NUM> to an end side (left side on the drawing) of the current collector <NUM>. Accordingly, as the electrode thickness in the area directly opposite to the first inclined portion <NUM> is prevented from being remarkably varied, and, as a result, the local rolling ratio may be prevented from remarkably increasing by the first inclined portion <NUM> and the second protruding portion <NUM>, the deformation and the crack may be prevented from occurring on the current collector <NUM> while the electrode is wound in advance.

<FIG> is a view illustrating an appearance of an electrode for a secondary battery obtainable from a manufacturing method in accordance with another exemplary embodiment. As illustrated in <FIG>, the second protruding portion <NUM> of the second active material layer <NUM> moves from the position directly opposite to the first inclined portion <NUM> to an opposite side (right side on the drawing) of the end of the current collector <NUM>. That is, the second protruding portion <NUM> is spaced a predetermined distance from the second inclined portion <NUM>. Accordingly, as previously described in an exemplary embodiment, as the electrode thickness in the area directly opposite to the first inclined portion <NUM> is prevented from being remarkably varied, and, as a result, the local rolling ratio is prevented from remarkably increasing by the first inclined portion <NUM> and the second protruding portion <NUM>, the deformation and the crack may be prevented from occurring on the current collector <NUM> in advance. Here, a configuration, in which the position of the second protruding portion <NUM> moves on the second active material layer, will be described below in detail in relation to the method for manufacturing the electrode for a secondary battery.

A method for manufacturing an electrode for a secondary battery in accordance with an exemplary embodiment includes: a process of preparing the current collector <NUM> in which the first active material layer <NUM> including the first inclined portion <NUM> and the first protruding portion <NUM> is provided on one surface thereof; a process of transferring the current collector <NUM> in one direction; and a process of forming the second active material layer <NUM> including the second inclined portion <NUM> and the second protruding portion <NUM> by applying the second active material on the other surface of the current collector <NUM>. Here, in the process of forming the second active material layer <NUM>, the second active material layer <NUM> is controlled in position so that the second protruding portion <NUM> is provided on a position that is not directly opposite to the first inclined portion <NUM> with respect to the current collector <NUM>.

A coating device for forming the active material layer includes: a supply roll for unwinding the current collector <NUM>, which is wound in a roll type, to continuously supply the unwound current collector in one direction; a coating die for applying active material slurry, which is supplied from an external active material slurry supply source, to the current collector <NUM>, which continuously moves in the one direction; a dryer for forming the active material layer on the current collector <NUM> by drying the active material slurry applied on the current collector <NUM>; and a withdrawal roll for withdrawing the current collector <NUM> in a rolled state by winding the current collector <NUM> on which the active material is provided.

Firstly, the process of preparing the current collector <NUM>, in which the first active material layer <NUM> including the first inclined portion <NUM> and the first protruding portion <NUM> is formed on one surface thereof, is performed by the above-described coating device. In the process of preparing the current collector <NUM>, the active material slurry is applied on one surface of the current collector <NUM> and then dried to form the first active material layer <NUM>. Here, the first active material layer <NUM> is formed on a position spaced by a distance of approximately <NUM> to approximately <NUM> from the end of the current collector <NUM>, so that the non-coated portion N is formed on one surface of the current collector <NUM>, the first inclined portion <NUM> is formed on the end of the first active material layer <NUM>, and the first protruding portion <NUM> is formed on a position spaced by a predetermined distance from the first inclined portion <NUM>.

Through the above-described process, the first active material layer <NUM> is formed on the one surface of the current collector <NUM>, and then the second active material layer <NUM> is formed on the other surface of the current collector <NUM> by the above-described coating device. The above-described process includes: a process of transferring the current collector <NUM> in one direction; and a process of forming the second active material layer <NUM> including the second inclined portion <NUM> and the second protruding portion <NUM> by applying the second active material, i.e., the second active material slurry, on the other surface of the current collector <NUM>. Here, the process of transferring the current collector <NUM> in one direction and the process of forming the second active material layer <NUM> of the other surface of the current collector <NUM> may be performed by the above-described coating device.

The method for manufacturing the electrode for a secondary battery in accordance with an exemplary embodiment controls the second protruding portion <NUM> of the second active material layer <NUM> is formed on a position that is not directly opposite to the first inclined portion <NUM> with respect to the current collector <NUM> in the process of forming the second active material layer <NUM>.

The above-described position control of the second protruding portion <NUM> may be performed by regulating an application pressure of the second active material layer <NUM>. That is, when the second active material layer <NUM> is formed on the other surface of the current collector <NUM>, the position of the second protruding portion <NUM> may be controlled by changing the application pressure of the coating die that supplies the second active material slurry.

Here, when the application pressure of the coating die for supplying the second active material slurry increases, as illustrated in <FIG>, the second protruding portion <NUM> of the second active material layer <NUM> may be transferred from the position directly opposite to the first inclined portion <NUM> to the end side (left side on the drawing) of the current collector <NUM>. Here, when the application pressure of the coating die for supplying the second active material slurry decreases, the second protruding portion <NUM> of the second active material layer <NUM> may be transferred from the position directly opposite to the first inclined portion <NUM> to an opposite side (right side on the drawing) of the end of the current collector <NUM>. Also, the position of the second protruding portion <NUM> may be adjusted by locally regulating the application pressure of the coating die for supplying the second active material slurry. That is, when the second active material slurry is supplied, as the application pressure of the coating die is reduced at the position of the first inclined portion <NUM>, the second protruding portion <NUM> may be controlled to be formed on the position that is not directly opposite to the first inclined portion <NUM> with respect to the current collector <NUM>.

As described above, the regulation of the application pressure of the coating die may be performed by controlling a valve for supplying the second active material slurry. That is, the coating die may include: an accommodation part for accommodating the second active material slurry; a nozzle for discharging the second active material slurry; and a valve for regulating an inner pressure of the accommodation part. Here, the valve may be a rod that is installed in the accommodation part in an ascending/descending manner to press the second active material slurry accommodated in the accommodation part. Here, the valve may be driven by a motor. Although an electric motor, which is operated by an electric signal, may be used for the above-described motor for driving the valve, a voice coil motor (VCM) is preferred to precisely regulate the inner pressure of the accommodation part. The voice coil motor is not varied in force according to positions because a coil thereof is operated in a uniform magnetic field and used for a micro-operation of several micrometers or less. Also, the voice coil motor may precisely regulate the application pressure of the coating die for supplying the second active material slurry because of a fast response speed thereof.

Also, the position control of the second protruding portion <NUM> may be performed by regulating the transfer speed of the current collector <NUM> when the second active material layer <NUM> is applied. That is, when the second active material layer <NUM> is formed on the other surface of the current collector <NUM>, the position of the second protruding portion <NUM> may be controlled by changing a rotation speed of each of the supply roll and the winding roll, which transfer the current collector <NUM> in one direction, and regulating the transfer speed of the current collector <NUM>.

Here, as illustrated in <FIG>, when the transfer speed of the current collector <NUM> decreases in the process of forming the second active material layer <NUM>, the second protruding portion <NUM> of the second active material layer <NUM> is transferred from the position directly opposite to the first inclined portion <NUM> to the end side (left side on the drawing) of the current collector <NUM>. Also, when the transfer speed of the current collector <NUM> increases in the process of forming the second active material layer <NUM>, the second protruding portion <NUM> of the second active material layer <NUM> is transferred from the position directly opposite to the first inclined portion <NUM> to the opposite side (right side on the drawing) of the end of the current collector <NUM>. Furthermore, as the transfer speed of the current collector <NUM> is locally changed, the position of the second protruding portion <NUM> may be adjusted. That is, when the current collector <NUM> is transferred, the second protruding portion <NUM> may be controlled to be formed on the position that is not directly opposite to the first inclined portion <NUM> with respect to the current collector <NUM> by increasing the transfer speed of the current collector at the position directly opposite to the first inclined portion <NUM>.

The above-described electrode in accordance with an exemplary embodiment may be used for a jellyroll-type electrode assembly. That is, as an electrode assembly in which a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, at least one of the positive electrode and negative electrode may be the above-described electrode for a secondary battery.

<FIG> is a view illustrating a state in which a pressure is applied to the current collector in the electrode for a secondary battery in accordance with an exemplary embodiment. Here, (a) of <FIG> illustrates a state in which a pressure is applied to the current collector <NUM> when the protruding portion <NUM> of the second active material layer <NUM> is disposed on the position directly opposite to the first inclined portion <NUM> of the first active material layer <NUM>, and (b) of <FIG> illustrates a state in which a pressure is applied to the current collector <NUM> when the protruding portion <NUM> of the second active material layer <NUM> is not disposed on the position directly opposite to the first inclined portion <NUM> of the first active material layer <NUM>.

Here, the protruding portion <NUM> of the second active material layer <NUM> has a width of approximately <NUM> and a height of approximately <NUM>, and the first inclined portion <NUM> of the first active material layer <NUM> has a thickness of approximately <NUM> from the current collector <NUM>.

As illustrated in (a) of <FIG>, when the protruding portion <NUM> of the second active material layer <NUM> is disposed on the position directly opposite to the first inclined portion <NUM> of the first active material layer <NUM>, the current collector <NUM> between the first active material layer <NUM> and the second active material layer <NUM> has a thickness of approximately <NUM>. However, in case of the electrode for a secondary battery in accordance with an exemplary embodiment in (b) of <FIG>, as the current collector <NUM> has a thickness of approximately <NUM>, a pressure applied to the current collector <NUM> decreases, and accordingly the local rolling ratio is effectively reduced.

The above-described a plastic strain of the current collector <NUM> according to the thickness variation thereof is illustrated in <FIG>. In <FIG>, a portion expressed by a dotted line represents the equivalent plastic strain (PEEQ) of the current collector <NUM> when the protruding portion <NUM> of the second active material layer <NUM> is disposed on the position directly opposite to the first inclined portion <NUM> of the first active material layer <NUM>, and a portion expressed by a solid line represents the equivalent plastic strain (PEEQ) of the current collector <NUM> when the protruding portion <NUM> of the second active material layer <NUM> is not disposed on the position directly opposite to the first inclined portion <NUM> of the first active material layer <NUM>.

As illustrated by a dotted line in <FIG>, when the protruding portion <NUM> of the second active material layer <NUM> is disposed on the position directly opposite to the first inclined portion <NUM> of the first active material layer <NUM>, the peak value of the equivalent plastic strain (PEEQ) of the current collector <NUM> dramatically increases to have a value of approximately <NUM> or more in the length of approximately <NUM> to approximately <NUM> from the end of the current collector <NUM> due to increase in the local rolling ratio. However, as illustrated as a solid line in <FIG> in accordance with an exemplary embodiment, when the protruding portion of the second active material layer <NUM> is not disposed on the position directly opposite to the first inclined portion <NUM> of the first active material layer <NUM>, the peak value of the equivalent plastic strain decreases by approximately <NUM> %, i.e., approximately maximum of <NUM>. Accordingly, the deformation of the current collector <NUM> may be prevented. That is, when the protruding portion <NUM> of the second active material layer <NUM> is disposed on the position directly opposite to the first inclined portion <NUM> of the first active material layer <NUM>, with respect to <NUM>,<NUM> (K=<NUM>,<NUM>) electrodes for a secondary battery manufactured by electrode winding, a crack is generated in <NUM> electrodes for a secondary battery to have a failure rate of approximately <NUM>%. however, in accordance with an exemplary embodiment, when the second active material layer <NUM> is not disposed on the position directly opposite to the first inclined portion <NUM> of the first active material layer <NUM>, as a crack is not generated on the manufactured <NUM>, <NUM> (K=<NUM>,<NUM>) electrodes for a secondary battery, the electrodes for a secondary battery may be manufactured with <NUM>% failure rate, and thus a crack generated while the electrode is manufactured may be prevented in advance.

As described above, according to the secondary battery electrode, the manufacturing method therefor, and the electrode assembly in accordance with an exemplary embodiment, as the protruding portion of the second active material layer <NUM> is controlled to be formed on the position that is not directly opposite to the inclined portion of the first active material layer <NUM> with respect to the current collector <NUM>, the pressure applied to the current collector <NUM> is relieved to prevent the current collector <NUM> from being deformed, and the crack generated while the electrode is manufactured may be prevented in advance.

Also, in accordance with an exemplary embodiment, as the shape of each of the first active material layer <NUM> and the second active material layer <NUM>, which are formed on the both surface of the current collector <NUM>, respectively, is controlled to prevent the thickness of the electrode from dramatically increasing, the electrode for a secondary battery having a uniform thickness may be achieved, and product safety, an economical efficiency, and a yield may be enhanced.

Claim 1:
A manufacturing method for a secondary battery electrode, comprising:
a process of preparing a current collector (<NUM>) on which a first active material layer (<NUM>) comprising a first inclined portion (<NUM>) and a first protruding portion (<NUM>) is formed on one surface thereof;
a process of transferring the current collector (<NUM>) in one direction; and
a process of forming a second active material layer (<NUM>) comprising a second inclined portion (<NUM>) and a second protruding portion (<NUM>) by applying a second active material on the other surface of the current collector,
wherein in the process of forming the second active material layer (<NUM>), the second protruding portion (<NUM>) is controlled in position on the second active material layer (<NUM>) so as to be formed on a position that is not directly opposite to the first incline portion (<NUM>) with respect to the current collector (<NUM>),
the second protruding portion (<NUM>) is spaced at a predetermined distance from the second inclined portion (<NUM>), and
the second protruding portion (<NUM>) is controlled in position by regulating an application pressure of the second active material layer (<NUM>), or
the second protruding portion (<NUM>) is controlled in position by regulating a transfer speed of the current collector (<NUM>).