KR20180097243A - Method for Preparation of Electrode Assembly Comprising Step of Assigning Electrode Plates - Google Patents

Abstract

The present invention relates to an electrode assembly manufacturing method including a process of arranging electrode plates, which manufactures an electrode assembly including two or more unit cells. According to the present invention, the electrode assembly manufacturing method comprises: a process (a) of locally coating an electrode active material on one or both surfaces of a current collector sheet to manufacture an electrode sheet including a coated part coated with the electrode active material and an uncoated part not coated with the electrode active material; a process (b) of notching an electrode tap on the uncoated part while including a through-hole to check alignment of the electrode plates so as to manufacture the electrode plate; a process (c) of manufacturing unit cells with a structure having a separation membrane interposed between the electrode plates; a process (d) of stacking the unit cells while checking the alignment of the electrode plates through the through-holes of the electrode tap; and a process (e) of mutually welding the electrode taps on the stacked unit cells and cutting a part of the electrode tap including the through-hole. The present invention saves manpower and time required for an inspection stage of a product, thereby increasing overall productivity.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing an electrode assembly,

The present invention relates to a method of manufacturing an electrode assembly including a process of aligning electrode plates.

In recent years, the demand for environmentally friendly alternative energy sources has become an indispensable factor for the future, as the increase in the price of energy sources due to depletion of fossil fuels and the interest in environmental pollution are amplified. Various researches on power generation technologies such as nuclear power, solar power, wind power, and tidal power have been continuing, and electric power storage devices for more efficient use of such generated energy have also been attracting much attention.

Particularly, as technology development and demand for mobile devices increase, the demand for batteries as energy sources is rapidly increasing. Recently, the use of secondary batteries as a power source for electric vehicles (EV) and hybrid electric vehicles (HEV) In addition, the use area has been expanded for use as a power auxiliary power source through a grid, and accordingly, a lot of researches on a battery that can meet various demands have been conducted.

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

Also, the secondary battery is classified according to the structure of the electrode assembly having the positive electrode, the negative electrode, and the separator interposed between the positive electrode and the negative electrode. Typically, the long battery- A stacked (stacked) electrode assembly in which a plurality of positive electrodes and negative electrodes cut in a predetermined size unit are sequentially stacked with a separator interposed therebetween, the jelly-roll type (wound type) electrode assembly having a structure in which a separator is interposed; In recent years, in order to solve the problems of the jelly-roll type electrode assembly and the stack type electrode assembly, an electrode assembly having an advanced structure, which is a combination of the jelly-roll type and the stack type, A stack / folding type electrode having a structure in which unit cells stacked with a separator interposed between an anode and a cathode are sequentially wound while being placed on a separation film Developed body lip.

In general, a positive electrode plate and a negative electrode plate constituting such an electrode assembly are formed by applying a positive electrode mixture or a negative electrode mixture onto the sheet in a process of continuously feeding a long sheet-like collector, and then pressing one end of the sheet by a press Notching to form a positive electrode tab and a negative electrode tab, respectively, and is manufactured by cutting to a desired size.

Meanwhile, the negative electrode plate is designed to have a larger area than the positive electrode plate. However, due to the automated laminating process, a unit cell may be manufactured with a part of the positive electrode plate positioned outside the region of the negative electrode plate, Thereby forming a short circuit in the battery.

Furthermore, since the area of the separation membrane, which is started between the electrode plates, is generally designed to be larger than the area of the electrode plate, there is a problem that the protruded anode plate is covered with the separation membrane and is hard to be visually confirmed.

In this way, it is very important that the unit cells are assembled in a state where the cathode and anode plates are aligned with each other. However, it is not easy to grasp the process of assembling the unit cells and whether the assembled unit cells are aligned by the naked eye, It is necessary to increase the time required for the inspection step.

Therefore, there is a high need for a technique capable of fundamentally solving such problems.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

The inventors of the present application have conducted intensive research and various experiments, and as a method for manufacturing an electrode assembly as described below, an electrode tab including a through hole for confirming alignment of electrode plates is manufactured, The present invention has been accomplished on the basis of this finding that the desired effect can be achieved when manufacturing the electrode assembly including the step of stacking the unit cells while confirming the alignment of the electrode plates through the through holes of the electrode assembly.

According to an aspect of the present invention, there is provided a method of manufacturing an electrode assembly including two or more unit cells,

(a) fabricating an electrode sheet including a collector sheet coated with an electrode active material locally on one side or both sides of the current collector sheet, and coated with the electrode active material and a non-coated electrode active material;

(b) forming an electrode plate by notching the electrode tab at the non-coated portion with the through hole for confirming alignment of the electrode plates;

(c) fabricating unit cells having a structure in which a separator is interposed between the electrode plates;

(d) stacking the unit cells while confirming the alignment of the electrode plates through the through-holes of the electrode tabs; And

(e) cutting a part of the electrode tab including the through-hole after the electrode tabs are welded to each other in the stacked unit cells;

.

Therefore, the method of manufacturing an electrode assembly according to the present invention can confirm whether or not the electrode plates of the unit cells are aligned with each other by checking the shapes of the through holes located in the electrode tabs of the unit cells. , It is possible to more easily judge the process of manufacturing the unit cell or the device adjustment so that the through hole can have a circular shape when the electrode plates are not aligned properly, thereby saving manpower and time required for the inspection step of the product , Thereby providing an effect of improving the overall productivity.

In one specific example, in the process (a), the electrode sheet is formed to have a structure in which an unoccupied portion is positioned between the first coating portion for manufacturing the first electrode plates and the second coating portion for manufacturing the second electrode plates .

Also, the electrode taps of the first electrode plates and the electrode taps of the second electrode plates may be notched in an alternating arrangement in the non-conductive portion.

The electrode tab may have a total width ranging from 5 mm to 9 mm and an overall length ranging from 6 mm to 9 mm.

If the total width of the electrode tab is less than 5 mm, the current generated in the electrode plate may not be properly transferred to the outside of the terminal due to the narrow width, and damage such as tearing occurs when the electrode tab is impacted in the full width direction easy to do. When the overall width exceeds 9 mm, the ratio of the entire width of the electrode tab to the entire width of the battery case is increased, so that the sealing force of the upper and lower portions of the battery case can be weaker than the electrode tab having a narrow width.

If the total length of the electrode tabs is less than 6 mm, the electrode taps of the unit cells stacked in step (e) are welded together, and then the remaining electrode taps are cut off while leaving a part of the electrode tabs. , There is a problem that a space for welding with the electrode lead is not sufficiently provided in the electrode tab. If the total length is more than 9 mm, there is no problem in the manufacturing process. However, since the portion where the electrode tab is not cut is constant in the process (e), the length of the electrode tab to be cut out becomes long and the productivity is deteriorated.

The diameter of the through hole may range from 1 mm to 3 mm, and in particular, the diameter of the through hole may range from 1.5 mm to 2.5 mm. When the diameter of the through-hole is less than 1 mm, the size of the through-hole may be small and it may be difficult to compare with the naked eye. When the diameter exceeds 3 mm, the ratio of the through- There is a problem that the part is cut off.

The through-hole may be located within a range of 6 mm or less from the full-length end of the electrode tab, specifically, 4 mm or less. In the case where the through hole is located at a position exceeding 6 mm from the end of the electrode tab, the electrode tap portion around the through hole remains in the cutting process in the cutting process, A problem may arise in welding.

The through-hole may be located at the center of the electrode tab. This is to prevent the one side portion of the through-hole from being excessively thinner than the other side when the through-hole is biased to one side in the electrode tab, so that the above-mentioned portion is cut off during the subsequent manufacturing process.

Meanwhile, in the step (d), the electrode plates may be aligned so that the inner surfaces of the through holes are aligned with each other, and whether or not the electrode plates in the unit cells are in a predetermined position can be visually confirmed have.

Specifically, when it is desired to know whether the upper electrode plate and the lower electrode plate constituting the unit cell are in the correct position, the shape of the through hole located in the electrode tab of the unit cell is observed. When the shape of the through-holes is circular, the electrode plates of the unit cells are aligned with each other, but when the shape is not circular, the electrode plates of the unit cells are arranged to be partially shifted. Further, when the shape of the through hole similar to that of the ellipse continuously appears, it can be a basis for judging the process or the apparatus in which the unit cell is manufactured so that the through hole is aligned and the circular shape can be formed.

In addition, the step (d) may include the following steps (d1) and (d2):

(d1) positioning the unit cells on a separation film; And

(d2) winding the separation film with the unit cells interposed therebetween.

On the other hand, in the step (e), the electrode tab including a portion ranging from 2 mm to 3.5 mm from the lower end of the through hole can be cut under the condition that the through hole is included.

When the electrode tab is cut out from the lower end of the through hole at a distance of less than 2 mm, there may arise a problem that the electrode tab portion around the through hole is left in the cutting process. If the distance exceeds 3.5 mm from the lower end of the through hole, So that the bonding force of the welded electrode tab is weakened so that the unit cell or the electrode plate can be easily separated by an external impact.

The present invention also provides an electrode assembly manufactured by the above manufacturing method, and a secondary battery in which such an electrode assembly is embedded in a battery case together with an electrolyte solution.

Hereinafter, other components of the secondary battery will be described.

The electrode is collectively referred to as a negative electrode and a positive electrode. The positive electrode may be prepared, for example, by applying a positive electrode mixture mixed with a positive electrode active material, a conductive material and a binder to a positive electrode collector, A filler may be further added.

The cathode current collector generally has a thickness of 3 to 300 탆 and is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Examples of the cathode current collector include stainless steel, aluminum, nickel, titanium , And a surface treated with carbon, nickel, titanium or silver on the surface of aluminum or stainless steel can be used. Specifically, aluminum can 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.

The cathode active material may be, 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 (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiV ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; A Ni-site type lithium nickel oxide expressed by the formula LiNi _1-x M _x O ₂ (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); Formula _{LiMn 2-x M x O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = 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. However, the present invention is not limited to these.

The conductive material is usually added in an amount of 1 to 30% by weight based on the total weight of the positive electrode material mixture containing the positive electrode 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 contained in the positive electrode is added to the binder in an amount of 1 to 30% by weight, based on the total weight of the mixture containing the positive electrode active material, as a component that assists in bonding between the active material and the conductive material and bonding to the current collector. 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-butadiene 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.

On the other hand, the negative electrode may be manufactured by applying a negative electrode mixture containing a negative electrode active material, a conductive material, and a binder to a negative electrode collector, and a filler or the like may further be optionally included.

The negative electrode current collector is not particularly limited as long as it has electrical conductivity without causing a chemical change in the battery. For example, the negative electrode current collector may be formed on the surface of copper, stainless steel, aluminum, nickel, titanium, sintered carbon, 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 present invention, the thickness of the anode current collector may be the same within the range of 3 to 201 [mu] m, but may have different values depending on the case.

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.

In one specific example, the separation membrane may be a polyolefin-based film commonly used in the art, and may be, for example, high density polyethylene, low density polyethylene, linear low density polyethylene, ultra high molecular weight polyethylene, polypropylene, polyethylene terephthalate polyethyleneterephthalate, polybutyleneterephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyetheretherketone, A sheet made of at least one selected from the group consisting of polyethersulfone, polyphenylene oxide, polyphenylenesulfrode, polyethylene naphthalene, and mixtures thereof.

The separation membrane may be made of the same material but is not limited thereto and may be made of materials different from each other depending on safety, energy density, and overall performance of the battery cell.

The pore size and porosity of the separation membrane are not particularly limited, but the porosity may be in the range of 10 to 95% and the pore size (diameter) may be 0.1 to 50 탆. When the pore size and porosity are 0.1 μm or less and 10% or less, respectively, it acts as a resistive layer. If the pore size and porosity are more than 50 μm and 95%, it is difficult to maintain the mechanical properties.

The electrolyte solution may be a non-aqueous electrolyte containing a lithium salt, and the non-aqueous electrolyte containing a lithium salt is composed of a non-aqueous electrolyte and a lithium salt. Non-aqueous organic solvents, organic solid electrolytes, inorganic solid electrolytes, The present invention is not limited thereto.

Examples of the non-aqueous organic solvent include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma -Butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile , Nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, Tetrahydrofuran derivatives, ether, methyl pyrophosphate, ethyl propionate and the like can be used.

Examples of the organic solid electrolyte include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, A polymer containing an acid dissociation group and the like may be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ can be used.

The lithium salt is a substance that is soluble in the nonaqueous electrolyte and includes, for example, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, chloroborane lithium, lower aliphatic carboxylate lithium, lithium tetraphenylborate, and imide.

The nonaqueous electrolyte may contain, for the purpose of improving charge / discharge characteristics, flame retardancy, etc., for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride and the like may be added have. In some cases, halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride may be further added to impart nonflammability. In order to improve the high-temperature storage characteristics, carbon dioxide gas may be further added. FEC (Fluoro-Ethylene Carbonate, PRS (Propene sultone), and the like.

In one specific _{example, LiPF 6, LiClO 4, LiBF} 4, LiN (SO 2 CF 3) 2 , such as a lithium salt, a highly dielectric solvent of DEC, DMC or EMC Fig solvent cyclic carbonate and a low viscosity of the EC or PC of And then adding it to a mixed solvent of linear carbonate to prepare a lithium salt-containing nonaqueous electrolyte.

The present invention also provides a battery pack including such a secondary battery as a unit cell, and a device including such a battery pack as a power source.

The device may be, for example, a notebook computer, a netbook, a tablet PC, a mobile phone, MP3, a wearable electronic device, a power tool, an electric vehicle (EV), a hybrid electric vehicle (HEV) , A plug-in hybrid electric vehicle (PHEV), an electric bike (E-bike), an electric scooter (E-scooter), an electric golf cart, However, the present invention is not limited thereto.

The structure and manufacturing method of such a device are well known in the art, so a detailed description thereof will be omitted herein.

As described above, the method of manufacturing an electrode assembly according to the present invention includes: fabricating an electrode tab including a through hole for confirming alignment of electrode plates, and aligning electrode plates through the through- By including the step of laminating, it is possible to visually confirm the misalignment of the unit cells with the naked eye, thereby saving manpower and time required for the inspection step of the product, thereby improving the overall productivity.

1 is a schematic view illustrating a process of fabricating a unit cell using general electrode plates;
2 is a plan view schematically showing an electrode sheet according to one embodiment of the present invention;
3 is a plan view schematically showing a unit cell according to an embodiment of the present invention;
4 is a plan view schematically showing various shapes in which the through holes are superimposed;
5 is a plan view schematically showing a process of manufacturing an electrode assembly according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

FIG. 1 schematically shows a process of manufacturing a unit cell using general electrode plates.

1, the unit cell 10 includes a main body 11 having a separation membrane (not shown) interposed between the positive and negative electrode plates 18 and 20 and the electrode tabs 12, 13 and 14 ).

The unit cell 10 includes a plate-like body portion 11 in which two or more structures in which a separation membrane is interposed between the positive electrode plate and the negative electrode plate are repeatedly laminated. The electrode tabs 12 and 13 , 14) protrude from a relatively narrow surface of the unit cell (10).

The body portion 11 includes a coating portion 16 coated with an electrode active material and an uncoated portion 15 not coated with an electrode active material and the positive electrode taps 12 and 14 are formed on the positive electrode plates 18 and 20, And the negative electrode tabs 13 extend from the respective negative electrode plates 19. [

In the case of the unit cell 10, a part of the positive electrode plate 17 is manufactured outside the negative electrode plate 19 due to the automated laminating process, and the electrode assembly including the unit cell and the secondary battery are used , Dendrites are generated in the region 17 of the positive electrode plate, causing a short circuit in the secondary battery.

2 is a schematic plan view of an electrode sheet according to one embodiment of the present invention.

2, the electrode sheet 100 is manufactured by applying an electrode active material to a current collector sheet 101 including a first electrode plate 110, a second electrode plate 120, and a non-coated portion 130 .

The current collector sheet 101 is relatively longer than the width and length, and the first electrode plate 110 is positioned on the lower side, the non-printed portion 130 on the center and the second electrode plate 120 on the upper side with respect to the longitudinal direction have.

The first electrode plate 110 and the second electrode plate 120 are coated with an electrode active material on one surface of the first electrode plate 110. The first electrode plate 110 is coated with an electrode active material and the second electrode plate 120 is coated with an electrode active material. And an electrode active material is applied on the upper surface. The first electrode plate 210 and the second electrode plate 220 have the same area and can produce electrode plates having the same area.

The first electrode tabs 141, 142, 143, 144, and 145 and the second electrode tabs 151, 152, 153, 154, and 155 are alternately arranged on the non-coated portion 130.

The first electrode tabs 141, 142, 143, 144 and 145 extend from the first electrode plate 110 and the second electrode tabs 151, 152, 153, 154, The electrode tabs 120 are formed to extend from the electrode tabs 120, and one through hole is formed for each of the first electrode tabs and the second electrode tabs.

In particular, the electrode plates manufactured from the first electrode plate 210 and the electrode plates fabricated from the second electrode plate 220 are formed in such a manner that, except for the direction in which the electrode active material is applied, The electrode tabs 141, 142, 143, 144, 145, 151, 152, 153, 154 and 155 and the through holes 161, 162, 163, 164, 165, 171, 172, 173, ) Are notated.

The through holes 161, 162, 163, 164, 165, 171, 172, 173, 174 and 175 are located at the center of the first electrode tabs and the second electrode tabs based on the total width of the electrode tabs.

The electrode tabs 141, 142, 143, 144, 145, 151, 152, 153, 154 and 155 are formed by cutting the electrode tabs, And is formed to be asymmetric.

3 is a schematic plan view of a unit cell according to an embodiment of the present invention.

3, the unit cell 200 includes an electrode plate 211 having a separation membrane (not shown) interposed between the positive electrode plates 218 and 220 and the negative electrode plate 219, and electrode tabs 212, 213 and 214 ). The coating portion to which the electrode active material is applied and the non-coating portion to which the electrode active material is not applied are not shown in the drawing.

The unit cell 200 has a separator (not shown) interposed between the positive and negative electrode plates 218 and 220 and the positive and negative electrode plates 218 and 220, .

The positive electrode tabs 212 and 214 of the positive electrode plates 218 and 220 are formed with through holes 232 and 234 to confirm whether the electrode plates are aligned from the shape in which the through holes are overlapped.

Fig. 4 schematically shows a plan view showing various shapes in which the through holes are overlapped.

Referring to FIG. 4, it can be seen whether the alignment of the electrode plates is good through the overlapping shape of the through holes.

According to the electrode tab 230a, since the overlapping shapes of the through holes are perfectly matched, it can be confirmed that the alignment of the electrode plates is good in both the horizontal direction, the vertical direction and the diagonal direction.

On the other hand, according to the electrode tab 230b, it can be seen that the overlapping shape of the through holes is shifted only in the horizontal direction. In the case of the electrode tab 230c, it is visually confirmed that the through holes are shifted only in the vertical direction. This indicates that the electrode plates cause alignment problems in the horizontal and vertical directions.

In the case where the same shape as the electrode tabs 230b and 230c is continuously displayed, it is possible to confirm that there is a problem in the stacking process of the unit cells in a short period of time, and the process re- Can be improved.

5 is a plan view schematically illustrating a process of manufacturing an electrode assembly according to an embodiment of the present invention.

5, the electrode assembly 300 includes positive electrode plates 318 and 320, negative electrode plates 319 and 321, a separator (not shown), and a partially cut electrode tab.

The unit cells that have undergone the alignment inspection are stacked via a separator, and then the positive electrode tabs 312 and 314 and the negative electrode tabs 313 and 315 are respectively welded so that the electrode tabs having the same polarity are electrically connected.

The welded positive electrode tabs and negative electrode tabs cut off a part of the electrode tab including the through hole so that the electrode tab (not shown) can be easily connected. When the electrode leads having the same polarity as that of the positive electrode tab and the negative electrode tab of the remaining portion after the cutting process are respectively welded, the electrode assembly is completed.

In the meantime, although the positive electrode plate is located at the uppermost and lowermost end of the unit cell with respect to the laminated direction, the present invention is also applicable to a unit cell in which the negative electrode plate is located at the uppermost and lowermost positions, These different unit cells can be applied when two or more electrode plates having the same polarity are included.

Although the present invention has been described with reference to the accompanying drawings, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (13)

A method of manufacturing an electrode assembly comprising two or more unit cells,
(a) fabricating an electrode sheet including a collector sheet coated with an electrode active material locally on one side or both sides of the current collector sheet, and coated with the electrode active material and a non-coated electrode active material;
(b) forming an electrode plate by notching the electrode tab at the non-coated portion with the through hole for confirming alignment of the electrode plates;
(c) fabricating unit cells having a structure in which a separator is interposed between the electrode plates;
(d) stacking the unit cells while confirming the alignment of the electrode plates through the through-holes of the electrode tabs; And
(e) cutting a part of the electrode tab including the through-hole after the electrode tabs are welded to each other in the stacked unit cells;
Wherein the electrode assembly includes a first electrode and a second electrode. The method according to claim 1, wherein the electrode sheet in the step (a) is formed in a structure in which an unoccupied portion is positioned between a first coating portion for manufacturing the first electrode plates and a second coating portion for manufacturing the second electrode plates Wherein the electrode assembly is made of a metal. 3. The method of claim 2, wherein the electrode taps of the first electrode plates and the electrode taps of the second electrode plates are notched in an alternating arrangement in the non-conductive portion. The method of claim 1, wherein the electrode tab has a total width ranging from 5 mm to 9 mm and an overall length ranging from 6 mm to 9 mm. The method according to claim 1, wherein the diameter of the through-hole is in a range of 1 mm to 3 mm. The method of claim 1, wherein the diameter of the through-hole is in a range of 1.5 mm to 2.5 mm. The method according to claim 1, wherein the through hole is located within a range of 6 mm from the electrical length end of the electrode tab. The method of claim 1, wherein the through-hole is located within a range of 4 mm from a full-length end of the electrode tab. The method of claim 1, wherein the through hole is located at a center of the electrode tab. The method of claim 1, wherein the electrode plates are aligned so that the inner surfaces of the through holes are aligned with each other in the step (d). The method of claim 1, wherein the step (d) comprises the following steps (d1) and (d2):
(d1) positioning the unit cells on a separation film; And
(d2) winding the separation film with the unit cells interposed therebetween. The method of manufacturing an electrode assembly according to claim 1, wherein, in the step (e), the electrode tab including a portion ranging from 2 mm to 3.5 mm from the lower end of the through hole is cut under the condition that the through hole is included. A secondary battery comprising an electrode assembly manufactured by the manufacturing method according to any one of claims 1 to 12.

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