KR101501363B1 - Electrode assembly and electrochemical cell containing the same - Google Patents

Abstract

The present invention relates to an electrode tab extending from an anode and a cathode; And an electrode lead coupled to the electrode tab, wherein a plurality of interlock patterns are formed in a plurality of stepped structures at a connection portion between the electrode tab and the electrode lead, and an electrochemical device including the electrode assembly .

Description

ELECTRODE ASSEMBLY AND ELECTROCHEMICAL CELL CONTAINING THE SAME Technical Field [1] The present invention relates to an electrode assembly,

The present invention relates to an electrode assembly improved in the strength of welding (welding) between an electrode tab and an electrode lead, and an electrochemical device including the electrode assembly.

With the rapid development of the electronics, communication, and computer industries, the demand for lithium secondary batteries has been increasing day by day as a power source for driving these portable electronic communication devices, as camcorders, mobile phones, notebooks, etc. have been remarkably developed.

As technology development and demand for mobile devices are increasing, the demand for batteries as energy sources is rapidly increasing, and accordingly, a lot of researches on batteries capable of meeting various demands have been conducted.

Typically, in view of the shape of the battery, there is a high demand for a prismatic secondary battery and a pouch-type secondary battery that can be applied to products such as mobile phones with a small thickness. In terms of materials, lithium ion batteries having high energy density, discharge voltage, There is a high demand for a lithium secondary battery such as a lithium ion polymer battery.

FIG. 1 schematically shows a general structure of a typical conventional pouch-type secondary battery as an exploded perspective view.

Referring to FIG. 1, a pouch type secondary battery 100 includes an electrode assembly 300, electrode tabs 310 and 320 extending from the electrode assembly 300, electrodes 310 and 320 welded to the electrode tabs 310 and 320, Leads 410 and 420, and a battery case 200 that accommodates the electrode assembly 300.

The electrode assembly 300 is a power generating element in which an anode and a cathode are sequentially stacked with a separator interposed therebetween, and has a stacked or stacked / folded structure. The electrode tabs 310 and 320 extend from the respective electrode plates of the electrode assembly 300 and the electrode leads 410 and 420 have a plurality of electrode tabs 310 and 320 extending from the respective electrode plates, And a part of the battery case 200 is exposed to the outside.

An insulating film 430 is attached to the upper and lower surfaces of the electrode leads 410 and 420 in order to increase the degree of sealing with the battery case 200 and at the same time to ensure an electrically insulated state. The case 200 is made of an aluminum laminate sheet, provides a space for accommodating the electrode assembly 300, and has a pouch shape as a whole. 1, a plurality of positive electrode tabs 310 and a plurality of negative electrode tabs 320 may be coupled to the electrode leads 410 and 420. In the stacked electrode assembly 300, The upper end is spaced apart from the electrode assembly 300 by a predetermined distance.

A method for welding the electrode tabs 310 and 320 of the rechargeable battery having the above-described structure to the leads will now be described in detail with reference to FIG.

FIG. 2 is an enlarged view of only the recesses of the electrode tab 310 and the electrode lead 410 of the electrode assembly of FIG. 1, and the electrode tab 310 and the electrode lead 410 are connected to each other Welding is performed.

Generally, the welding of the section B can be realized by performing ultrasonic welding, or by a plastic deformation between welding materials by using a clinching equipment. However, the conventional joining method using a clinching apparatus as in the prior art has a problem that the strength of welding is low and it is difficult to realize a reliable joining structure.

Korean Patent No. 10-1068618

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide an electrode assembly having a reliable coupling structure between an electrode tab and an electrode lead of a secondary battery, .

In the present invention, an electrode tab extending from an anode and a cathode; And an electrode lead coupled to the electrode tab, wherein a plurality of interlock patterns are formed in a plurality of stepped structures at a connection portion between the electrode tab and the electrode lead.

In addition, according to the present invention, there is provided a method of manufacturing an electrochemical cell, comprising the steps of: a) forming an electrode tab extending from an anode and a cathode and a part of an electrode lead coupled to the electrode tab overlap; b) performing a first clinching process using a first pin and a first die at a bonding site of the overlapped electrode tab and the electrode lead; c) performing a (1 + n) clinching process on the first cleated binding site via a (1 + n) pin and a (1 + n) (Wherein n is a natural number of 1 to 5).

According to the present invention, when the electrode tabs and the electrode leads are coupled to each other in the secondary battery, the cleaning process is repeated two or more times to improve the bonding strength of the electrode tabs and improve the short circuit between the electrode tabs and the electrode leads have.

1 shows a structure of a general secondary battery.
FIG. 2 is a conceptual view for explaining the welding process of the electrode tab and the electrode lead in the structure of FIG. 1. FIG.
3 is a flow chart for explaining the general principle of the clinching process.
4 is a process conceptual diagram for explaining a clinching process according to the present invention.
5 to 8 are conceptual diagrams for explaining a two-step cleaning process according to an embodiment of the present invention.
9 is a graph showing the welding strength of a secondary battery manufactured according to an embodiment of the present invention.

Hereinafter, the configuration and operation according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description with reference to the accompanying drawings, the same reference numerals denote the same elements regardless of the reference numerals, and redundant description thereof will be omitted. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

It is an object of the present invention to provide a technique for manufacturing an electrode assembly in which reliability of coupling between members is improved by applying an electrode tab and an electrode lead cleaning process of a secondary battery.

First, in the present invention, an electrode tab extending from an anode and a cathode;

And an electrode lead coupled to the electrode tab,

And a plurality of interlock patterns formed in a plurality of stepped structures is formed at a joint portion between the electrode tab and the electrode lead.

At this time, the multiple engagement pattern may include a structure in which at least two protruding patterns having different depths and widths are overlapped at a portion where the electrode tabs and the electrode leads are stacked and joined.

That is, the multiple engaging patterns may be formed of a first pattern protruding downward and a second pattern protruding downward from a bottom surface of the first pattern. At this time, each of the edge portions of the first pattern and the second pattern may be formed so as to protrude further downward than the lower surface of the first pattern and the second pattern.

The electrode assembly according to the present invention having such a structure may include a multiple engagement pattern having at least two protrusions having different depths and widths at the connection sites of the electrode tabs and the electrode leads.

In the present invention,

a) arranging the electrode tab extending from the anode and the cathode and a part of the electrode lead coupled to the electrode tab overlap;

b) performing a first clinching process using a first pin and a first die at a bonding site of the overlapped electrode tab and the electrode lead; And

c) performing a (1 + n) clinching process on the first cleated binding site via a (1 + n) pin and a (1 + n) (Wherein n is a natural number of 1 to 5).

In this case, the step of performing the (1 + n) clinching may include using a (1 + n) pressing pin having a diameter larger than that of the first pressing pin, The electrode tab and the electrode lead can be pressed again by using a (1 + n) die having a low temperature.

Also, in the method of the present invention, steps b) and c) may be performed in the reverse order, and steps b) and c) may be repeated at least twice.

Meanwhile, the 'clinching process' refers to a technique in which a metal member to be joined is disposed between a pressing pin and a die, and a joining portion is pressed using a pressing pin, thereby welding the two materials while causing plastic deformation. Specifically, as shown in FIG. 3, when A) two materials to be welded are stacked and arranged, and B) pressurization is carried out by using a press pin, the materials C to F are sequentially pressed in the pressing direction The protrusions are formed, and at the same time, the interlocks are finally formed by plastic deformation, so that bonding is achieved.

4, the electrode tabs 310 and 320 and the electrode leads 410 and 420 in FIG. 1 are joined together through a clinching process. The two members are welded together by two or more clinching processes Are formed at the same joint portion to form multiple engagement patterns that are realized in a plurality of stepped structures to increase the strength of welding.

That is, the process according to the present invention includes arranging the electrode tabs 310 extending in the anode and the cathode and the electrode leads 410 coupled to the electrode tabs so as to overlap each other, and (a) (1 + n) < / RTI > pins (1 < n >) to the first cleated coupling portion after performing a first clinching process through the first pin (510) (1 + n) die 540 and the (1 + n) die 540 through the first (1 + n)

The step (1 + n) of clinching may be performed by using a (1 + n) pin 530 having a diameter T2 larger than the diameter T1 of the first fin 510, The electrode tab and the electrode lead may be pressed again using a (1 + n) die 540 having a depth d2 lower than the depth d1 of the first die 520. [

At this time, the pressing conditions of the first clinching and the first + n clinching may be the same or different. Specifically, depending on the number of tabs to be assembled and the thickness of the lead, the pressurizing conditions may be weakly performed, or may be performed strongly. Because the load limit varies depending on the size and materials of the clinching tool, To 1000 kgf.

Also, the steps (a) and (b) may be performed in the reverse order, or the steps (a) and (b) may be repeated at least twice.

Specifically, when the above-mentioned 'n' is a natural number, for example, when n is '1', the second clinching process after the first clinching process can be superimposed on the first clinching region it means. Needless to say, such a process can be carried out a plurality of times. Hereinafter, the process of performing the two-time clinching can be described in more detail with reference to FIG.

First, as shown in FIG. 4A, the electrode tabs 310 and the electrode leads 410 are welded to each other so as to be in contact with each other, and the upper first pressing pins 510 and the holes are formed After the first die 520 is placed between the first die 520 and the first die 520, the first presser pin 510 is used to press the first presser pin into the hole of the first die 520. In this case, primary coupling according to the clinching described in Fig. 3 is performed. As a result of the primary bonding, a first pattern protruding downward by a depth d1 of the first die is realized as shown in Fig.

Next, as shown in FIG. 4 (b), by using the second presser pin 530 having a larger diameter T2 than the press pin used in the first clinching process, the first die 510 The second clinching process is performed again on the first clinched area using the second die 540 having a depth d2 that is lower than the depth d1 of the holes of the first clinch area. The result of the second clinching process realizes the shape of the welded portion as shown in FIG.

As a result of the secondary bonding, a second pattern protruding from the bottom of the bottom surface of the first pattern is implemented as shown in FIG. 6, and the electrode tab 310 and the electrode lead 410 X, Y) are formed on the surface of the substrate W in a plurality of stepped structures.

As described above, the electrode assembly of the present invention may include multiple engagement patterns having at least two protrusions having different depths and widths at the joining sites of the electrode tabs and the electrode leads.

6, the first pattern protruding downward and the second pattern protruding from the bottom of the bottom surface of the first pattern are connected in a stepped shape. .

In addition, the edge portions of the first pattern and the second pattern are caused to protrude from the lower surface of the first pattern and the second pattern by the two-time clinching process, and a large number of engaging portions (X, Y) And the bonding reliability as the plastic deformation portions are increased is also improved.

In the present invention, the first cleansing process using the first pressing pin and the first die of FIG. 4 and the second cleansing process to be performed thereafter are performed in the reverse order as shown in FIGS. 7 and 8 It can also be implemented.

That is, as shown in FIG. 7, after a relatively large pattern is formed by using the second pressing pin and the second die, a first pressing pin whose diameter is smaller than that of the second fin is used, The electrode tab and the electrode lead are pressed again by using the first die having a large depth, so that the structure as shown in FIG. 8 can be realized.

Meanwhile, the electrode assembly having a coupling structure according to the present invention has a structure in which a cathode / separator / cathode is stacked, and the electrolyte assembly is accommodated in a pouch, and then an electrolyte is injected into the electrode assembly. The electrode assembly having the joining portion according to the present invention may have a structure of a winding type, a stack type, or a stack / folding type structure. Hereinafter, specific materials and structural characteristics of the constituent elements of the electrode assembly according to the present invention will be described.

anode

In the present invention, the electrodes formed on the basic unit are distinguished into an anode or a cathode, and the anode and the cathode are bonded to each other with a separator interposed therebetween. The anode is prepared, for example, by applying a mixture of a cathode active material, a conductive material and a binder on a cathode current collector, followed by drying and pressing. If necessary, a filler may be further added to the mixture. Such a structure can be applied to the process in the form of a sheet, which is mounted on a loading roll.

(Anode collector)

The cathode current collector generally has a thickness of 3 to 500 mu m. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, sintered carbon, aluminum or stainless steel A surface treated with carbon, nickel, titanium, silver or the like may be used. The current collector may have fine irregularities on the surface thereof to increase the adhesive force of the cathode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are possible. In the above-described embodiment of the present invention, the electrode tab may have the same material as the material of the positive electrode collector.

(Cathode active material)

The cathode active material may be a lithium secondary battery, for example, a layered compound such as lithium cobalt oxide (LiCoO ₂ ) or lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _{2 - x} O ₄ wherein x is 0 to 0.33, LiMnO ₃ , LiMn ₂ O ₃ and LiMnO ₂ ; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; A Ni-site type lithium nickel oxide represented by the formula LiNi _{1 - x} M _x O ₂ (where M is Co, Mn, Al, Cu, Fe, Mg, B or Ga and x is 0.01 to 0.3); Formula _{LiMn 2 - x M x O 2} ( where, M is Co, Ni, Fe, Cr, and Zn, or Ta, x is 0.01 to 0.1 Im) or Li ₂ Mn ₃ MO ₈ (wherein, M is Fe, Co, Ni, Cu, or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds, Fe ₂ (MoO ₄ ) ₃ , and the like, but are not limited thereto.

The conductive material is usually added in an amount of 1 to 50% by weight based on the total weight of the mixture including the cathode active material. Such a conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, for example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The binder is a component that assists in bonding of the active material and the conductive material and bonding to the current collector, and is usually added in an amount of 1 to 50 wt% based on the total weight of the mixture containing the cathode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers and the like.

The filler is optionally used as a component for suppressing the expansion of the anode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. Examples of the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

cathode

The negative electrode is prepared by applying, drying and pressing an anode active material on an anode current collector, and may optionally further include a conductive material, a binder, a filler, and the like as described above. Such a structure can be applied to the process in the form of a sheet, which is mounted on a loading roll.

(Cathode collector)

The negative electrode collector is generally made to have a thickness of 3 to 500 mu m. Such an anode current collector is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples of the anode current collector include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, a surface of copper or stainless steel A surface treated with carbon, nickel, titanium, silver or the like, an aluminum-cadmium alloy, or the like can be used. In addition, like the positive electrode collector, fine unevenness can be formed on the surface to enhance the bonding force of the negative electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams and nonwoven fabrics. In the above-described embodiment of the present invention, the electrode tab may have the same material as the material of the negative electrode collector.

(Negative electrode active material)

The negative electrode active material may include, for example, carbon such as non-graphitized carbon or graphite carbon; _{Li x Fe 2 O 3 (0≤x≤1} ), Li x WO 2 (0≤x≤1), Sn x Me 1 - x Me 'y O z (Me: Mn, Fe, Pb, Ge; Me' : Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, Halogen, 0 < x &lt; Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, and Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

Membrane

The separation membrane according to the present invention can form a basic unit body by a simple lamination process regardless of a folding process or a roll process, thereby realizing simple lamination. Particularly, in the laminator, the separation membrane, the anode and the cathode are adhered to each other by melting the separator sheet itself inside the laminator by heat and adhering. This ensures stable interfacial contact between the bar electrode and the separator sheet to keep the pressure constant.

The separation membrane interposed between the anode and the cathode of the separator sheet or cell is not particularly limited as long as it exhibits insulation and has a porous structure capable of moving ions, and the separation membrane and the separation membrane sheet may be the same material or not It is possible.

The separator or separator sheet may be, for example, an insulating thin film having high ion permeability and mechanical strength, and the separator or separator sheet generally has a pore diameter of 0.01 to 10 mu m, 300 mu m. Examples of the separator or separator sheet include olefin polymers such as polypropylene, which is resistant to chemicals and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte may also serve as a separation membrane. Preferably, a multilayer film produced by a polyethylene film, a polypropylene film, or a combination of these films, or a film made of polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or poly A polyvinylidene fluoride hexafluoropropylene copolymer or the like, or a polymer film for a gel-type polymer electrolyte.

It is preferable that the separation membrane has an adhesive function by heat fusion to constitute a basic unit cell, and the separation membrane sheet does not necessarily have such a function, but it is preferable to use one having an adhesive function.

In addition, the present invention can provide an electrochemical device including the electrode assembly. That is, the electrochemical device is an electrochemical cell that generates electricity by an electrochemical reaction between a positive electrode and a negative electrode. Typical examples thereof include super capacitors, ultra capacitors, secondary batteries, fuel cells, A sensor, an electrolytic apparatus, an electrochemical reactor, and the like, among which a secondary battery is particularly preferable.

The secondary battery has a structure in which a chargeable and dischargeable electrode assembly is embedded in a battery case while being impregnated with an ion-containing electrolytic solution. In one preferred example, the secondary battery may be a lithium secondary battery.

Recently, a lithium secondary battery has attracted much attention as a power source for a large-sized device as well as a small-sized mobile device, and it is desirable to have a small weight when applied to such a field. As one of the measures for reducing the weight of the secondary battery, a structure in which the electrode assembly is embedded in the pouch-shaped case of the aluminum laminate sheet may be preferable. Such a lithium secondary battery is well known in the art, so a description thereof will be omitted herein.

In addition, as described above, when used as a power source for a middle- or large-sized device, a secondary battery having a structure capable of suppressing the deterioration of operating performance to a maximum extent during long- term use, having excellent lifespan characteristics, and mass- From this point of view, the secondary battery including the electrode assembly of the present invention can be preferably used for a middle- or large-sized battery module using the unit battery.

In the case of a battery pack including a battery module including a plurality of secondary batteries, a power tool; An electric vehicle selected from the group consisting of Electric Vehicle (EV), Hybrid Electric Vehicle (HEV), and Plug-in Hybrid Electric Vehicle (PHEV); E-bike; An e-scooter; Electric golf cart; Electric truck; And an electric commercial vehicle.

The middle- or large-sized battery module is configured to provide a large-capacity large-capacity battery by connecting a plurality of unit cells in a serial manner or a serial / parallel manner, which is well known in the art and thus will not be described herein.

Hereinafter, an example of manufacturing an electrode assembly having a coupling portion in which a multiple engagement pattern according to the present invention is realized will be described.

Example

(Example 1)

First, a conventional electrode assembly in which a positive electrode / separator / negative electrode is sequentially formed is housed in a battery compartment of a battery case, and a plurality of electrode taps protruding from a current collector of the electrode assembly are welded to the electrode leads. And arranged between the first pressure pin and the first die in which the hole is formed.

Next, a primary clinching A process was performed to press the first pressing pin into the hole of the first die. Next, a second-order clinching B process was performed in which the electrode tab and the electrode lead were pressed and coupled using a second die having a second pressing pin and a hole. The diameters of the first and second pressing pins and the hole depths of the first and second dies are shown in Table 1 below.

Next, an electrolytic solution was injected into the battery case, and the upper and lower laminate sheets of the battery case were thermally fused to each other to form a sealing portion in the battery case to manufacture a secondary battery. FIG. 9 shows the results of welding the electrode tabs and the electrode leads obtained by overlapping and implementing such a clinching process.

(Example 2)

A secondary battery was manufactured in the same manner as in Example 1, except that secondary cleaning was performed after the primary cleaning step and then primary cleaning was performed after the secondary cleaning step in reverse order. FIG. 9 shows the results of welding the electrode tabs and the electrode leads obtained by overlapping and implementing such a clinching process.

Referring to FIG. 9, in the clinching A, the welding strength of the electrode tab and the electrode lead was 48.82 kgf, and in the clinching B, the welding strength was 74.57 kgf.

However, when comparing the first embodiment (see FIGS. 5 and 6) of performing the cleansing B after the cleansing A and the second embodiment (see FIGS. 7 and 8) of performing the cleansing A process after the cleansing B, It was confirmed that the welding strength of Example 1 was 96.12 kgf, and the welding strength of Example 2 was improved by a maximum of 2 times by 90.01 kgf, as compared with the results of performing one cleaning process individually.

(Comparative Example)

A pouch-type secondary battery was fabricated in the same manner as in Example 1, except that the first cleaning step was performed in place of the second cleaning step in the first embodiment.

(Experimental Example 1)

The tensile strength of each of the batteries prepared in Examples 1 and 2 and Comparative Examples was tested, and the results are shown in Table 2 below.

In this experiment, 100 cells were repeatedly performed, and the same tensile pressure was applied to check whether the welds were short-circuited.

The tensile strength
(N / mm2) Example 1
Number of paragraphs Example 2
Number of paragraphs Comparative example
Number of paragraphs 10 0 0 0 50 0 0 3 100 0 0 12 150 0 0 15

As shown in Table 2, in the case of the secondary batteries manufactured in Examples 1 and 2, short-circuit failure for the tensile test did not occur in all 100 batteries, while in the battery of Comparative Example, 30% Lt; / RTI &gt;

In the foregoing detailed description of the present invention, specific examples have been described. However, various modifications are possible within the scope of the present invention. The technical idea of the present invention should not be limited to the embodiments of the present invention but should be determined by the equivalents of the claims and the claims.

100: secondary battery
200: Battery case
300: electrode assembly
310, 320: electrode tab
410, 420: lead portion (electrode lead)
411: lead film
430: insulating film
510: first pressing pin
530: Second presser pin
520: first die
540:
X, Y:

Claims (14)

An electrode tab extending from the anode and the cathode;
And an electrode lead coupled to the electrode tab,
Wherein a plurality of interlock patterns are formed in a plurality of stepped structures at a connection portion between the electrode tabs and the electrode leads,
Wherein the multiple engaging patterns include a structure in which at least two protruding patterns having different depths and widths are overlapped in a region where the electrode tabs and the electrode leads are laminated and overlapped. delete The method according to claim 1,
Wherein the multiple engaging patterns are formed of a first pattern protruding downwardly and a second pattern protruding downward from a bottom surface of the first pattern. The method of claim 3,
Wherein edge portions of the first pattern and the second pattern are formed so as to protrude further downward than lower surfaces of the first pattern and the second pattern, respectively. The method according to claim 1,
Wherein the electrode assembly includes a multiple engagement pattern having at least two protrusions having depths and widths different from each other at a joint portion between the electrode tabs and the electrode leads. a) arranging the electrode tab extending from the anode and the cathode and a part of the electrode lead coupled to the electrode tab overlap;
b) performing a first clinching process using a first pin and a first die at a bonding site of the overlapped electrode tab and the electrode lead; And
c) performing a (1 + n) clinching process on the first cleated binding site via a (1 + n) pin and a (1 + n) 1 to 5). &Lt; / RTI &gt; The method of claim 6,
The step (1 + n) of performing the (1 + n)
(1 + n) pressing pin having a larger diameter than the first pressing pin is used,
And pressing the electrode tab and the electrode lead again using a (1 + n) die having a depth lower than the depth of the first die. The method of claim 6,
Wherein the steps b) and c) are performed in reverse order. The method of claim 6,
Wherein the steps b) and c) are repeated at least twice. An electrochemical device comprising an electrode assembly according to claim 1. The method of claim 10,
Wherein the electrode assembly comprises one of a winding type, a stack type, and a stack / folding type structure. The method of claim 10,
Wherein the electrode assembly includes Li ₂ MnO ₃ and LiMO ₂ (M is a transition metal element) as a cathode active material coated on the cathode current collector. The method of claim 10,
Wherein the electrochemical device is a secondary battery. The method according to any one of claims 10 to 13,
Wherein the electrochemical device is any one selected from the group consisting of a battery module including a secondary battery and a battery pack including a plurality of battery modules.

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