KR20130124098A - Method for preparing bi-cell - Google Patents

Abstract

The present invention relates to a manufacturing method of bi-cell which contains a fundamental laminated structure of cathode/anode/cathode or anode/cathode/anode. The said manufacturing method comprises steps of: (a) a step of laminating a separating membrane and a second electrode on a first electrode; (b) a step of inspecting defects of the first electrode and the second electrode and accurate position arrangement in the assembly of the step(a); (c) a step of laminating a separating membrane and a third electrode on the second electrode in the assembly of the step(a); and (d) a step of inspecting defects of the third electrode and the second electrode and accurate position arrangement in the assembly of the step(c).

Description

Method for Preparing Bicell {Method for Preparing Bi-cell}

The present invention is a method for manufacturing a bi-cell having a basic laminated structure of anode / cathode / anode or cathode / anode / cathode, (a) by laminating a separator and a second electrode on the first electrode step; (b) inspecting whether the first electrode and the second electrode are defective and in-situ arrangement in the assembly of step (a); (c) stacking and laminating a separator and a third electrode on the second electrode in the assembly of step (a); (d) inspecting whether or not the third electrode is defective and in-situ arrangement in the assembly of step (c).

As technology development and demand for mobile devices have increased, there has been a rapid increase in demand for secondary batteries as energy sources. Among such secondary batteries, lithium secondary batteries, which exhibit high energy density and operational potential, long cycle life, Batteries have been commercialized and widely used.

The electrode assembly of the anode / separator / cathode structure constituting the secondary battery is largely classified into a jelly-roll type (winding type) and a stack type (laminate type) depending on its structure. In the jelly-roll type electrode assembly, an electrode active material or the like is coated on a metal foil used as a current collector, dried and pressed, cut into a band shape having a desired width and length, and a cathode and an anode are diaphragm- . Although the jelly-roll type electrode assembly is suitable for a cylindrical battery, when applied to a square or pouch type battery, it has disadvantages such as separation of electrode active material and low space utilization. On the other hand, the stacked electrode assembly has a structure in which a plurality of anode and cathode unit members are sequentially laminated, and it is easy to obtain a rectangular shape. However, when the manufacturing process is troublesome and impact is applied, .

In order to solve this problem, the electrode assembly of the advanced structure of the jelly-roll type and the stacked form, a full cell or anode (cathode) / separator / cathode of a certain unit size of the anode / separator / cathode structure An electrode assembly was developed in which a bicell having a structure of (cathode) / membrane / anode (cathode) was folded using a continuous membrane film having a long length, which is the applicant's Korean Patent Application Publication No. 2001-82058 No. 2001-82059, 2001-82060, and the like. In the present application, the electrode assembly having such a structure is referred to as a stack / foldable electrode assembly.

The existing manufacturing method of the bicell consists of laminating the electrode in three stages together with the separator and inspecting whether the electrode is defective or not.

However, since the bi-cell is composed of at least a three-stage stacking structure, it is difficult to inspect whether the electrodes located therein are defective or not.

Therefore, there is a high need for a technique for solving such a problem.

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

After extensive research and various experiments, the inventors of the present application proceed with defect inspection in two stages through two-stage lamination in the bi-cell lamination process, so that defects of not only external electrodes but also internal electrodes can be eliminated. It confirmed that it could test and came to complete this invention.

Accordingly, the present invention is a method for manufacturing a bi-cell having a basic laminated structure of anode / cathode / anode or cathode / anode / cathode,

(a) laminating a separator and a second electrode on the first electrode;

(b) inspecting whether the first electrode and the second electrode are defective and in-situ arrangement in the assembly of step (a);

(c) stacking and laminating a separator and a third electrode on the second electrode in the assembly of step (a);

(d) inspecting the third electrode for defects and in-situ alignment in the assembly of step (c);

It provides a method for producing a bicell comprising a.

The bicell is a cell in which the same electrodes are positioned on both sides of the cell, such as a unit structure of an anode / separator / cathode / separator / anode and a unit structure of a cathode / separator / anode / separator / cathode. In this specification, a cell having an anode / separation membrane / cathode / separation membrane / anode structure is referred to as a dC type bicell d, and a cell having a cathode / separation membrane / anode / separation membrane / cathode structure is referred to as a dA type bicell d. That is, a cell in which the anodes are located at both sides is called a "C-type bicell", and a cell in which the cathodes are located at both sides is called a "A-type bicell".

If the electrodes on both sides of the cell have the same structure, the number of the positive electrode, the negative electrode, and the separator constituting the bi-cell are not particularly limited.

The bicell is manufactured by mutually bonding the positive electrode and the negative electrode with a separator interposed therebetween. A preferable example of such a bonding method is a heat fusion bonding method.

In the bicell, the positive electrode is prepared by, for example, applying a mixture of a positive electrode active material, a conductive material, and a binder onto a positive electrode current collector, followed by drying and pressing, and further adding a filler to the mixture, if necessary.

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.

The cathode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), 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 , LiFe 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 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 whiskeys 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 which 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 30% by weight 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.

On the other hand, the negative electrode is manufactured 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.

The negative electrode current 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.

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.

The separation membrane is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 mu m and the thickness is generally 5 to 300 mu m. Such separation membranes include, for example, olefinic polymers such as polypropylene, which are chemically resistant 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. The separator film used in the present invention may or may not be the same material as the separator.

The conventional bicell lamination process includes laminating the first electrode, the second electrode, and the third electrode with a separator interposed therebetween, and inspecting whether the electrode is defective or not and in-situ arrangement is performed. In this case, it is very difficult to inspect whether the second electrode located therein is defective and the alignment is correct.

In the manufacturing method according to the present invention by dividing the lamination process of the bi-cell in two stages, the step of inspecting whether the electrode is defective or the exact position is also divided into two stages for both the internal and external electrodes whether the defect and the exact position You can check the array.

In a secondary battery that manufactures an electrode assembly by stacking / folding a plurality of bicells, whether or not an electrode is defective or in-situ is very important because it may greatly affect the safety of the battery itself or a battery module. Specifically, the use of a defective electrode may cause damage to the separator, and furthermore, explosion of the battery.

In one example of the invention, the test is

An inspection unit which sends an image signal obtained by photographing the shape and position of the electrode to the following control unit;

A control unit which checks the shape and arrangement of electrodes based on the image signal received from the inspection unit and controls the operation of the following sorter;

A sorter for sorting a defective assembly according to a signal from the controller;

It may be made by a vision inspection unit including a.

The inspection unit may be, for example, a camera installed at an upper portion and / or a lower portion of the laminated electrode to photograph the electrode. In one preferred example, the inspection unit may generate an image signal obtained by photographing the whole of the electrode so as to confirm whether the electrode itself is defective or not.

The control unit may be configured to compare the electrode form and arrangement of the image signal with the preset form and arrangement, and send a signal to sort the defective unit when the electrode form and arrangement are different from the preset arrangement.

The preset array refers to information about a shape and a normal array normalized in a corresponding process with respect to the electrode, and the controller compares the shape and the arrangement of the electrodes acquired from the image signal with the preset array. It is possible to check whether the shape and the arrangement of deviate from the preset arrangement. That is, when the inspection unit photographs the shape and arrangement of the electrodes to produce an image signal, the control unit stores standardized form and regular array information about such electrodes, and compares them with the electrode form and arrangement from the inspection unit.

The present invention also provides a bicell manufactured using the method described above, and provides an electrode assembly including the bicell as a unit cell.

The electrode assembly may be a stack type electrode assembly in which unit cells are sequentially stacked with a separator interposed therebetween, or a stack / foldable electrode assembly having a unit cell folded using a continuous membrane film having a long length.

The present invention also provides a secondary battery composed of the electrode assembly and the electrolyte. As a preferred example, the secondary battery may be a lithium secondary battery composed of the electrode assembly and a lithium salt-containing nonaqueous electrolyte.

The lithium salt-containing nonaqueous electrolyte solution is composed of an electrolyte solution and a lithium salt. As the electrolyte solution, a nonaqueous organic solvent, an organic solid electrolyte, and an inorganic solid electrolyte may be used.

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 Nonionic organic solvents such as tetrahydrofuran derivatives, ethers, 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 ionic 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, sulfates and the like of Li, such as Li ₄ SiO ₄ -LiI-LiOH, Li ₃ PO ₄ -Li ₂ S-SiS ₂ , and the like, may be used.

The lithium salt is a material that is good to dissolve in the non-aqueous electrolyte, 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 ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, chloroborane lithium, lower aliphatic lithium carbonate, lithium phenyl borate, imide and the like can be used.

For the purpose of improving the charge / discharge characteristics and the flame retardancy, the electrolytic solution is preferably mixed with an organic solvent such as pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, Benzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, . In some cases, in order to impart nonflammability, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further included, and carbon dioxide gas may be further included to improve high temperature storage characteristics, and FEC (Fluoro-Ethylene) may be further included. carbonate), PRS (propene sultone) and the like may be further included.

The present invention also provides a battery module including the secondary battery as a unit cell and a battery pack including the battery module.

The battery pack may be preferably used as a power source for medium and large devices and / or power tools.

Preferred examples of the medium-to-large devices include electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs) driven by electric motors. Electric vehicles including); An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; And a power storage system, but the present invention is not limited thereto.

As described above, the bicell manufacturing method according to the present invention can determine the failure of the electrode located inside, it is possible to improve the safety of the secondary battery.

1 is a schematic diagram showing a part of a conventional method for manufacturing a bicell;
Figure 2 is a schematic diagram showing a part of the manufacturing method of the bi-cell according to one embodiment of the present invention;
3 is a block diagram of a vision inspection unit according to an exemplary embodiment of the present invention.

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

1 is a schematic diagram showing a part of a conventional method for manufacturing a bicell, and FIG. 2 is a schematic diagram showing a part of a method for manufacturing a bicell according to an embodiment of the present invention.

First, referring to FIG. 1, according to the conventional bicell manufacturing method, the anodes 111 and 112 and the cathode 120 are laminated with each other with the separators 131 and 132 interposed therebetween to manufacture the bicells. The inspection unit (141, 142), respectively located in the upper and lower parts of the manufactured bi-cell is inspected whether the electrode is defective or in position.

However, in the above method, it is not possible to inspect whether the negative electrode 120 located inside the manufactured bicell is defective or not. When the defect of the negative electrode 120 is present, the safety of the battery may be greatly reduced, which is not preferable.

Referring to FIG. 2, in the bicell manufacturing method according to the present invention, the first separator 211 and the cathode 220 are positioned to be stacked and laminated, and then, the intermediate assembly of the fabricated fabricated after the lamination. Examine whether the first positive electrode 211 and the negative electrode 220 is defective or not in the correct position through the first inspection unit 241 and the second inspection unit 242, respectively located in the upper and lower portions, and in the next step the cathode 220 After laminating the second separator 232 and the second anode 212 and manufacturing the bicell, the second inspection unit 243 inspects whether or not the second anode 212 is defective and is aligned in position. .

Through the above-described method, by inspecting whether the electrodes located therein are defective or in the correct position, there is an effect that the safety of the battery due to the failure of the electrodes can be prevented.

3 is a schematic diagram of a vision inspection unit according to an embodiment of the present invention.

Referring to FIG. 3, the first inspector 310, the second inspector 320, and the third inspector 330 are independently connected to the controller 340. That is, the image signal photographed by each inspection unit is transmitted to the control unit 340, and the control unit 340 compares the electrode form and arrangement of the captured image signal with the preset form and arrangement, and the electrode form and arrangement is preset. If there is a difference between, and the sorter 350 is sent a signal to sort the defective.

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 (11)

A method of manufacturing a bi-cell having a basic stacked structure of anode / cathode / anode or cathode / anode / cathode,
(a) laminating a separator and a second electrode on the first electrode;
(b) inspecting whether the first electrode and the second electrode are defective and in-situ arrangement in the assembly of step (a);
(c) stacking and laminating a separator and a third electrode on the second electrode in the assembly of step (a);
(d) inspecting the third electrode for defects and in-situ alignment in the assembly of step (c);
Bicell manufacturing method comprising a. The method of claim 1, wherein the inspection,
An inspection unit which sends an image signal obtained by photographing the shape and position of the electrode to the following control unit;
A control unit which checks the shape and arrangement of electrodes based on the image signal received from the inspection unit and controls the operation of the following sorter;
A sorter for sorting a defective assembly according to a signal from the controller;
Bicell manufacturing method characterized by comprising a vision (vision) inspection unit comprising a. The method of claim 2, wherein the inspection unit is a camera. The method according to claim 2, wherein the control unit compares the electrode form and arrangement of the image signal with the preset form and arrangement, and sends a signal to sort the defective unit when the electrode form and arrangement are different from the preset arrangement. Method for producing a bicell, characterized in that. Bicell manufactured according to any one of claims 1 to 4. An electrode assembly comprising a bicell according to claim 5 as a unit cell. A secondary battery comprising the electrode assembly according to claim 6. A battery module comprising the secondary battery according to claim 7. A battery pack comprising the battery module according to claim 8. The battery pack according to claim 9, wherein the battery pack is used as a power source for medium and large devices and / or power tools. The battery pack according to claim 10, wherein the medium-large device is an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a system for storing power.

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