KR101877601B1 - A Cap Assembly of Novel Structure and Cylindrical Battery Comprising the Same - Google Patents

Abstract

The present invention relates to a cap assembly mounted on an open upper end of a can having a structure in which an electrode assembly (jelly-roll) having a positive electrode / separator / negative electrode structure is embedded in a cylindrical can, comprising: (a) Venting vent; (b) a top cap mounted on the safety vent and having a through-hole for discharging gas, the top cap forming a protruding terminal; And (c) a sealing member which surrounds the outer circumferential surfaces of the elements, and the sealing member is vertically bent corresponding to the outer circumferential side surfaces of the safety vent and the top cap, And the cap assembly is integrated.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a cap assembly having a novel structure and a cylindrical battery including the same.

The present invention relates to a cap assembly having a novel structure and a cylindrical battery including the cap assembly.

As technology development and demand for mobile devices have increased, the demand for secondary batteries as energy sources has been rapidly increasing. Many researches have been conducted on lithium secondary batteries with high energy density and discharge voltage among such secondary batteries. .

The secondary battery is classified into a cylindrical battery and a prismatic battery in which the electrode assembly is housed in a cylindrical or rectangular metal can according to the shape of the battery case, and a pouch-shaped battery in which the electrode assembly is housed in a pouch-shaped case of an aluminum laminate sheet .

In addition, the electrode assembly incorporated in the battery case is a chargeable / dischargeable power generation device formed of a lamination structure of a positive electrode / separator / negative electrode. The electrode assembly is a jelly-roll type electrode assembly in which a separator is interposed between a positive electrode and a negative electrode coated with an active material, Structure and a stacked structure in which a plurality of positive electrodes and negative electrodes of a predetermined size are sequentially stacked with a separator interposed therebetween. Among them, the jelly-roll type electrode assembly has an advantage of being easy to manufacture and having a high energy density per weight.

Generally, such a jelly-roll type electrode assembly is used for a cylindrical battery, and a cylindrical battery tends to undergo repeated expansion and contraction during charging and discharging. In order to solve the above-mentioned problem of safety of the battery, the cap assembly of the cylindrical battery is provided with a safety vent, A plurality of safety elements such as a PTC device and a current interrupt device (CID) are installed, and the safety vent covers the outer peripheral surfaces of the PTC device, the CID, the top cap, etc., To prevent it from being damaged.

In the case of the cylindrical battery used in the power tool of the conventional structure, the end portion of the safety vent is bent in a manner to enclose the outer circumferential surface of the top cap, and then the upper portion is coupled by laser welding at the upper portion. However, in this construction, additional assembly equipment and laser welding equipment are required for culing the ends of the safety vents. That is, in order to perform the curling operation of the safety vent, a heat treatment process after the forming of the safety vent and an additional welding process are required, which causes an increase in manufacturing cost and causes an appearance defect due to additional welding.

Therefore, there is a high need for a technique capable of reducing appearance defects and manufacturing costs due to laser welding in a cap assembly of a cylindrical battery.

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.

More specifically, it is an object of the present invention to provide a cap assembly structure of a cylindrical battery having a specific structure to prevent defects and loss of the battery caused in the welding process by omitting the curling process and the laser welding process of the safety vent The present invention relates to a cylindrical cap assembly.

According to an aspect of the present invention,

1. A cap assembly mounted on an open top of a can in a battery having a structure in which an electrode assembly (jelly-roll) having a positive electrode / separator / negative electrode structure is embedded in a cylindrical can,

(a) a safety vent that discharges gas while rupturing when a high pressure in the cell occurs;

(b) a top cap mounted on the safety vent and having a through-hole for discharging gas, the top cap forming a protruding terminal; And

(c) a sealing member surrounding and sealing the outer peripheral surfaces of the elements;

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The sealing member has a structure in which the safety vent and the top cap are integrally formed with the safety vent and the top cap in a vertically bent shape corresponding to the outer circumferential side of the top cap.

Therefore, according to the present invention, since the sealing member is integrated with the safety vent and the top cap, the curling process and the laser welding process of the safety vent can be omitted.

In some cases, the structure may further include an annular PTC element mounted between the safety vent and the top cap.

In one specific example, the upper end of the sealing member may be a structure that surrounds the upper end surface of the can, and preferably, the sealing member is integrated with the safety vent and the top cap by insert injection molding . That is, since the sealing member is structured so as to be interposed in the space of the outer circumferential surface of the safety vent and the top cap, the safety vent can be commonly used for the type of product (mobile product or power tool product) to which the cylindrical battery is applied It is possible to reduce the cost required for manufacturing parts.

The sealing member may be a plastic resin or an insulated metal plate, but is not limited thereto.

In one specific example, the safety vent may have a structure in which a current blocking member is provided at the lower end of the safety vent to cut off the current when the pressure inside the battery rises.

According to the present invention, at least a part of the electrode tab of the jelly-roll may be coated with an insulating material or wrapped with an insulating film. In a specific example, the electrode tab of the jelly- Can be applied.

The present invention also provides a cylindrical battery comprising the cap assembly, wherein the battery is preferably a lithium ion battery or a lithium ion polymer battery.

For reference, the lithium secondary battery comprises a positive electrode, a negative electrode, a separator, and a lithium-containing non-aqueous electrolyte.

The anode may be prepared, for example, by applying a slurry prepared by mixing a cathode mixture to a solvent such as NMP, and then drying and rolling the cathode slurry.

In addition to the positive electrode active material, the positive electrode mixture may optionally include a conductive material, a binder, a filler, and the like.

The cathode active material is a material capable of causing an electrochemical reaction. Examples of the lithium transition metal oxide include lithium cobalt oxide (LiCoO ₂ ) containing two or more transition metals and substituted with one or more transition metals, lithium Layered compounds such as nickel oxide (LiNiO ₂ ); Lithium manganese oxide substituted with one or more transition metals; Formula _{LiNi 1-y M y O 2} ( where, M = Co, Mn, Al , Cu, Fe, Mg, B, Cr, Zn or Ga and Lim, 0.01≤y≤0.7 include one or more elements of the element) A lithium nickel-based oxide represented by the following formula: _{Li 1 + z Ni 1/3 Co 1/3} Mn 1/3 O 2, Li 1 + z Ni 0.4 Mn 0.4 Co 0.2 O 2 , such as _{Li 1 + z Ni b Mn c} Co 1- (b + c + d _{) M d O (2-e} ) A e ( where, -0.5≤z≤0.5, 0.1≤b≤0.8, 0.1≤c≤0.8, 0≤d≤0.2 , 0≤e≤0.2, b + c + d <1, M = Al, Mg, Cr, Ti, Si or Y, and A = F, P or Cl; lithium nickel cobalt manganese composite oxide; And the formula _{Li 1 + x M 1-y} M 'y PO 4-z X z ( wherein, M = a transition metal, preferably Fe, Mn, Co or Ni, M' = Al, Mg or Ti, X = F, S or N, and -0.5? X? +0.5, 0? Y? 0.5, and 0? Z? 0.1), but the present invention is not limited thereto.

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 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 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, and various copolymers.

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

The cathode current collector is generally made to have a thickness of 3 to 500 mu m. Such a positive electrode collector is not particularly limited as long as it has conductivity without causing chemical change to the battery, and may be formed on the surface of stainless steel, aluminum, nickel, titanium, sintered carbon or aluminum or stainless steel 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 negative electrode is prepared, for example, by applying a negative electrode mixture containing a negative electrode active material on a negative electrode collector and then drying the same. The negative electrode mixture may contain a conductive material, a binder, a filler, May be included.

Examples of the negative electrode active material include carbon and graphite materials such as natural graphite, artificial graphite, expanded graphite, carbon fiber, non-graphitizable carbon, carbon black, carbon nanotube, fullerene and activated carbon; Metals such as Al, Si, Sn, Ag, Bi, Mg, Zn, In, Ge, Pb, Pd, Pt and Ti which can be alloyed with lithium and compounds containing these elements; Complexes of metals and their compounds and carbon and graphite materials; Lithium-containing nitrides, and the like. Among them, a carbon-based active material, a silicon-based active material, a tin-based active material, or a silicon-carbon based active material is more preferable, and these may be used singly or in combination of two or more.

The negative electrode collector is generally made to have a thickness of 3 to 500 mu m. The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery. Examples of the negative electrode current collector include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, copper or stainless steel Surface-treated with carbon, nickel, titanium, silver or the like, 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 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 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 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 material that is readily soluble 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 carboxylic acid lithium, lithium tetraphenyl borate and imide have.

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, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further added to impart nonflammability, or a carbon dioxide gas may be further added to improve high-temperature storage characteristics.

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As described above, in the cap assembly of the cylindrical battery according to the present invention, the sealing member is integrally formed by insert injection molding in the form of wrapping the safety vent and the outer circumferential surface of the top cap, whereby a curling process of the safety vent, It is possible to omit the welding process and to reduce manufacturing cost and product defects.

1 is a schematic cross-sectional view illustrating an upper structure of a cylindrical rechargeable battery 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 is a schematic cross-sectional view illustrating an upper structure of a cylindrical rechargeable battery according to an embodiment of the present invention.

Referring to FIG. 1, a cylindrical secondary battery 100 according to the present invention includes a cap assembly 400, and the cap assembly 400 includes a current blocking safety element 440 for blocking current when a high voltage is generated in the battery A top cap 410, which is connected to a lower portion of the safety vent 430 and has a through-hole for discharging gas and forms a protruding terminal, is mounted on the safety vent 430. A beading portion 210 is formed at an upper end of the upper opening of the can 200.

The sealing member 600 is injected into the outer peripheral surface of the top cap 410 and the safety vent 430 by insert injection molding and is integrally formed with the top cap 410 and the safety vent 430, And the outer circumferential surface 610 of the sealing member 600 is enclosed and sealed.

That is, since the sealing member 600 is formed integrally with the top cap 410 and the outer periphery of the safety vent 430, the end of the safety vent 430 is bent to cover the top cap 410 Can be omitted.

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 (12)

1. A cap assembly mounted on an open top of a can in a battery having a structure in which an electrode assembly (jelly-roll) having a positive electrode / separator / negative electrode structure is embedded in a cylindrical can,
(a) a safety vent that discharges gas while rupturing when a high pressure in the cell occurs;
(b) a top cap mounted on the safety vent and having a through-hole for discharging gas, the top cap forming a protruding terminal; And
(c) a sealing member enclosing the safety vent and the outer circumferential surface of the top cap and sealing the same;
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Wherein the sealing member is integrally formed with the safety vent and the top cap in a vertically bent shape corresponding to the outer circumferential side of the safety vent and the top cap,
Further comprising an annular PTC element mounted between the safety vent and the top cap,
The upper end of the sealing member surrounds the upper end surface of the can,
Wherein the sealing member is a plastic resin,
At least a part of the electrode tab of the jelly-roll is coated with an insulating material or wrapped with an insulating film,
Wherein the sealing member is integrated with the safety vent and the top cap by insert injection molding. delete delete delete delete The cap assembly according to claim 1, wherein a current blocking member is provided at a lower end of the safety vent to cut off current when the pressure inside the battery rises. delete The cap assembly of claim 1, wherein the electrode tab of the jelly-roll is a positive electrode tab. 9. A cylindrical battery comprising a cap assembly according to any one of claims 1, 6 and 8. The cylindrical battery according to claim 9, wherein the battery is a lithium secondary battery. delete delete

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