KR102178188B1 - Battery Case Forming Device Equipped with Punch Head of Low Friction Force - Google Patents

Abstract

The present invention is an apparatus for forming a battery case including an electrode assembly storage unit in which an electrode assembly can be embedded, and a recessed or through-type open groove having a size corresponding to the electrode assembly storage unit is formed, and for manufacturing a battery case A die in which the sheet-like base material is located on the upper surface; A punch having a shape corresponding to the open groove, located above the open groove for deep drawing on the sheet-like base material, and a punch head to be introduced into the open groove when descending has a low coefficient of friction ( a punch made of a material of frictional coefficient); And a stripper for pressing and fixing both ends of the sheet-like base material to a die for deep drawing. It provides a battery case molding apparatus comprising: a.

Description

Battery Case Forming Device Equipped with Punch Head of Low Friction Force}

The present invention relates to an apparatus for forming a battery case having a punch head having low friction.

Secondary batteries are widely used as power sources for mobile devices such as cell phones, laptops, and camcorders. In particular, the use of lithium secondary batteries is rapidly increasing due to the advantages of high operating voltage and high energy density per unit weight.

These lithium secondary batteries are also classified into lithium ion batteries, lithium ion polymer batteries, and lithium polymer batteries depending on the composition of the electrode and electrolyte, and among them, the use of lithium ion polymer batteries that are less likely to leak and are easy to manufacture. This is increasing.

Lithium-ion polymer battery (LiPB) is a structure in which an electrode assembly obtained by heat-sealing an electrode (anode and negative electrode) and a separator is impregnated with an electrolyte solution, and is mainly used in a form in which the electrode assembly is sealed in a pouch-shaped case of an aluminum laminate sheet. Therefore, lithium-ion polymer batteries are often referred to as pouch-type batteries.

1 schematically shows a general structure of a typical secondary battery including a stacked electrode assembly.

Referring to FIG. 1, the secondary battery 10 includes an electrode assembly 30 made of a positive electrode, a negative electrode, and a separator disposed therebetween in a pouch-shaped battery case 20, and the positive and negative electrodes thereof. The tabs 31 and 32 are welded to the two electrode leads 40 and 41, respectively, and are sealed (sealed) so that they are exposed to the outside of the battery case 20.

The battery case 20 is made of a flexible packaging material such as an aluminum laminate sheet, and includes a case body 21 including a concave-shaped storage unit 23 on which the electrode assembly 30 can be seated and the body 21 It consists of a cover 22 to which one side is connected.

The electrode assembly 30 used in the secondary battery 10 may have a jelly roll type structure or a stack/folding type structure in addition to the stack type structure as shown in FIG. 1. In the stacked electrode assembly 30, a plurality of positive electrode tabs 31 and a plurality of negative electrode tabs 32 are welded to electrode leads 40 and 41, respectively.

The battery case 20 for a secondary battery is deformed by pressing a sheet-like base material, for example, a base material of an aluminum laminate sheet, using a rectangular parallelepiped-shaped punch corresponding to the storage part 23, and then the storage part 23 It is manufactured by cutting the size of the cover in the longitudinal direction and the size corresponding to the gas pocket in the width direction.

Conventionally, a battery case has been manufactured by deep forming a laminate sheet using a punch made of a material such as alloy tool steel, for example, SKD11.

However, punches made of alloy tool steel have a high coefficient of friction with respect to the laminate sheet, so when the punch presses the base material, wrinkles and whitening phenomena occur in the corners of the storage unit, and cracks may occur if the degree is severe. have.

Therefore, there is a high need for a technology capable of fundamentally solving these problems and reducing the defective rate when forming a battery case in the battery cell manufacturing process.

An object of the present invention is to solve the problems of the prior art and technical problems that have been requested from the past.

An object of the present invention is to provide a battery case molding apparatus that prevents crack failure of the storage unit and secures safety by forming a storage unit by pressing using a punch of a new shape at a portion where the storage unit of the battery case is to be formed in a sheet-like base material. To provide.

A battery case molding apparatus according to the present invention for achieving this object is an apparatus for molding a battery case including an electrode assembly receiving portion in which an electrode assembly may be embedded,

A die in which an indented or through-type open groove having a size corresponding to the electrode assembly receiving portion is formed, and a sheet-like base material for manufacturing a battery case is positioned on an upper surface;

A punch having a shape corresponding to the open groove, located above the open groove for deep drawing on the sheet-like base material, and a punch head to be introduced into the open groove when descending has a low coefficient of friction ( a punch made of a material of frictional coefficient); And

A stripper for pressing and fixing both ends of the sheet-like base material to a die for deep drawing;

It may be composed of a structure including.

Therefore, in the battery case forming apparatus according to the present invention, by forming a punch head of a punch that is deeply drawn in contact with a sheet-like base material with a material having a low coefficient of friction, it is possible to prevent crack failure of the battery case receiving portion and secure safety. .

The sheet-like base material may be made of a laminate sheet including a metal layer and a resin layer suitable for, for example, a pouch-type battery, and specifically, an upper layer of a first polymer resin, an intermediate layer of a barrier metal, and a second polymer resin. It can be made in the lower layer. Here, the first polymer resin layer may be specifically a heat-fusible polymer resin, for example, a non-stretched polypropylene resin. The barrier metal may be aluminum, for example, and the second polymer resin may be a resin having excellent weather resistance, such as nylon resin, polyethylene terephthalate resin, polyethylene naphthalate resin, or the like. However, it goes without saying that the type of material is not limited to the above examples.

In one embodiment of the present invention, the coefficient of friction of the punch head may be in the range of 0.04 to 0.2. Since the conventional punch made of alloy tool steel has a coefficient of friction in the range of 0.4 or more, cracks could be generated in the sheet-like base material during deep drawing for forming the receiving part due to relatively large friction with the sheet-like base material. On the other hand, the battery case molding apparatus according to the present invention introduces a punch head having a frictional force coefficient within the range of 0.04 to 0.2, which is relatively lower than that of a conventional punch, so that cracking of the sheet-like base material due to deep drawing of the punch can be prevented. have.

As an embodiment of the punch head, the material of the punch head may be made of polytetrafluoroethylene, but any material that satisfies a range within the coefficient of friction of the punch head is not limited thereto.

As another embodiment of the punch head, the material of the punch head may be made of stainless steel, and when the punch head is made of stainless steel, the coefficient of friction of the punch head is 0.2 to It can be made within the range of 0.4.

The present invention also provides lubricity to the punch head by adding oil or moisture to the surface of the punch head, as well as constituting the punch head with a material having a low coefficient of friction, thereby lowering the friction force between the punch head and the sheet-shaped base material. I can.

In another embodiment of the present invention, the punch,

Punch body made of alloy tool steel and the vertical movement of the punch; And

A punch head formed at the lower end of the main body, made of a material having a low coefficient of friction, and contacting a sheet-shaped base material;

It can consist of.

That is, in order to reinforce the overall rigidity of the punch, the punch body in which the punch is elevated and lowered may be formed of alloy tool steel, and only the portion of the punch head that directly contacts the sheet-like base material may be formed of a material having a low coefficient of friction.

The present invention also provides a battery cell manufactured using the battery case molding apparatus.

The type of the battery cell is not particularly limited, but as a specific example, it may be a lithium secondary battery such as a lithium ion battery or a lithium ion polymer battery having advantages such as high energy density, discharge voltage, and output stability.

In general, a lithium secondary battery is composed of a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte containing a lithium salt.

The positive electrode is prepared, for example, by coating a mixture of a positive electrode active material, a conductive material, and a binder on a positive electrode current collector, followed by drying, and if necessary, a filler may be further added to the mixture.

The positive electrode active material may include a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; Lithium manganese oxides such as chemical formula Li1+xMn2-xO4 (wherein x is 0 to 0.33), LiMnO3, LiMn2O3, and LiMnO2; Lithium copper oxide (Li2CuO2); Vanadium oxides such as LiV3O8, LiFe3O4, V2O5, and Cu2V2O7; Ni site-type lithium nickel oxide represented by the formula LiNi1-xMxO2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3); Formula LiMn2-xMxO2 (here, M = Co, Ni, Fe, Cr, Zn or Ta, x = 0.01 ~ 0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn) Lithium manganese composite oxide; LiMn2O4 in which part of Li in the formula is substituted with alkaline earth metal ions; Disulfide compounds; Fe2(MoO4)3 etc. are mentioned, but it is not limited only to these.

The conductive material is typically added in an amount of 1 to 30% by weight based on the total weight of the mixture including the positive electrode active material. Such a conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and examples thereof include graphite such as natural graphite or artificial graphite; Carbon blacks such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; Conductive fibers such as carbon fibers and metal fibers; 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 may be used.

The binder is a component that aids in bonding of an active material and a conductive material and bonding to a current collector, and is typically added in an amount of 1 to 30% by weight based on the total weight of the mixture including the positive electrode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, recycled cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, and various copolymers.

The filler is selectively used as a component that suppresses the expansion of the positive electrode, and is not particularly limited as long as it is a fibrous material without causing chemical changes to the battery, and examples thereof include olefin-based polymers such as polyethylene and polypropylene; Fibrous materials such as glass fiber and carbon fiber are used.

The negative electrode is manufactured by coating and drying a negative electrode active material on a negative electrode current collector, and if necessary, components as described above may be optionally further included.

Examples of the negative active material include carbon such as non-graphitized carbon and graphite-based carbon; LixFe2O3 (0≤x≤1), LixWO2 (0≤x≤1), SnxMe1-xMe'yOz (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, Group 1 of the periodic table, Metal complex oxides such as Group 2 and Group 3 elements, halogen, 0<x≦1; 1≦y≦3; 1≦z≦8); Lithium metal; Lithium alloy; Silicon-based alloys; Tin-based alloys; Metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, and Bi2O5; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

The separator and the separation film are 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 μm, and the thickness is generally 5 to 130 μm. Examples of such separation membranes include olefin-based polymers such as polypropylene having chemical resistance and hydrophobicity; Sheets or non-woven fabrics made of glass fiber or polyethylene are used. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.

In addition, in one specific example, in order to improve the safety of the battery, the separator and/or the separation film may be an organic/inorganic composite porous SRS (Safety-Reinforcing Separators) separator.

The SRS separator is manufactured by using inorganic particles and a binder polymer as active layer components on a polyolefin-based separator substrate, and at this time, the pore structure included in the separator substrate itself and the interstitial volume between inorganic particles as the active layer component It has a uniform pore structure formed.

In the case of using such an organic/inorganic composite porous separator, compared to the case of using a conventional separator, there is an advantage in that it is possible to suppress an increase in the thickness of the battery due to swelling during the formation process. When a polymer that can be gelled when impregnated with a liquid electrolyte is used, it can be used as an electrolyte at the same time.

In addition, since the organic/inorganic composite porous separator can exhibit excellent adhesion characteristics by controlling the content of inorganic particles and binder polymers as active layer components in the separator, the battery assembly process can be easily performed.

The inorganic particles are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in the present invention are not particularly limited as long as the oxidation and/or reduction reaction does not occur in the operating voltage range (eg, 0 to 5V based on Li/Li+) of the applied battery. Particularly, in the case of using inorganic particles having ion transfer capability, it is possible to improve the performance by increasing the ionic conductivity in the electrochemical device, so it is preferable that the ion conductivity is as high as possible. In addition, when the inorganic particles have a high density, it is difficult to disperse during coating, as well as a problem of weight increase during battery manufacturing, so it is preferable that the density is as small as possible. Further, in the case of an inorganic material having a high dielectric constant, the ionic conductivity of the electrolyte may be improved by contributing to an increase in the degree of dissociation of an electrolyte salt, such as a lithium salt, in a liquid electrolyte.

The lithium salt-containing non-aqueous electrolyte is composed of a polar organic electrolyte and a lithium salt. As the electrolyte, a non-aqueous liquid electrolyte, an organic solid electrolyte, an inorganic solid electrolyte, or the like is used.

As the non-aqueous liquid electrolyte, for example, N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma -Butyl lactone, 1,2-dimethoxy ethane, tetrahydroxy franc (franc), 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolone, formamide, dimethylformamide, dioxolone , Acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid tryster, trimethoxymethane, dioxolone derivative, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbo Aprotic organic solvents such as nate derivatives, tetrahydrofuran derivatives, ethers, methyl pyropionate and ethyl propionate may be used.

As the organic solid electrolyte, for example, a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, a poly agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, A polymer or the like containing an ionic dissociating group may be used.

Examples of the inorganic solid electrolyte include Li such as Li3N, LiI, Li5NI2, Li3N-LiI-LiOH, LiSiO4, LiSiO4-LiI-LiOH, Li2SiS3, Li4SiO4, Li4SiO4-LiI-LiOH, and Li3PO4-Li2S-SiS2. Nitrides, halides, sulfates, and the like can be used.

The lithium salt is a material that is soluble in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO4, LiBF4, LiB10Cl10, LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, (CF3SO2) 2NLi, lithium chloroborane, lithium lower aliphatic carboxylic acid, lithium tetraphenylborate, imide, and the like can be used.

In addition, non-aqueous electrolytes include pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexaphosphate triamide for the purpose of improving charge/discharge properties and flame retardancy, etc. , Nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxy ethanol, aluminum trichloride, etc. May be. In some cases, in order to impart non-flammability, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further included, and carbon dioxide gas may be further included in order to improve high-temperature storage characteristics.

The present invention also provides a battery pack including one or more of the battery cells.

The present invention also provides a device including one or more of the battery packs as power sources.

The device may be selected from a mobile phone, a wearable electronic device, a portable computer, a smart pad, a netbook, a light electronic vehicle (LEV), an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, and a power storage device.

Since the structure of these devices and a method of manufacturing them are known in the art, detailed descriptions thereof will be omitted in the present specification.

As described above, in the battery case molding apparatus according to the present invention, by forming a punch head of a punch that is deeply drawn in contact with a sheet-shaped base material, a material having a low coefficient of friction is formed, crack failure of the battery case receiving portion is prevented and safety is improved. Can be secured.

1 is an exploded view of a conventional lithium secondary battery;
2 is a schematic diagram of a battery case molding apparatus according to an embodiment of the present invention;
3 is a schematic diagram of an apparatus for forming a battery case according to another embodiment of the present invention.

Hereinafter, it will be described with reference to the drawings according to an embodiment of the present invention, but this is for an easier understanding of the present invention, and the scope of the present invention is not limited thereto.

Figure 2 is a schematic diagram of a battery case molding apparatus according to an embodiment of the present invention.

Referring to FIG. 2, the battery case forming apparatus 100 includes a die 110, a punch 120, and a stripper 130.

The die 110 has a through-type open groove 111 having a size corresponding to the electrode assembly receiving portion, and has a structure in which a sheet-shaped base material 900 for manufacturing a battery case is positioned on an upper surface.

The punch 120 has a shape corresponding to the open groove 111, is located above the open groove 111 for deep drawing on the sheet-like base material 900, and descends in the direction of the arrow to the sheet-like base material 900 By pressing, the electrode assembly housing portion is formed in the sheet-like base material 900. The punch head 121 to be introduced into the open groove 111 is made of a material having a low coefficient of friction. Specifically, the material of the punch head 121 is made of polytetrafluoroethylene, and when made of such a material, the coefficient of friction of the punch head 121 is determined within the range of 0.04 to 0.2.

The stripper 130 has a structure that pressurizes both ends of the sheet-like base material 900 to the die 110 for deep drawing.

3 is a schematic diagram of a battery case molding apparatus according to another embodiment of the present invention.

3, the punch 220 of the battery case forming apparatus 200 is formed at the lower end of the punch body 222 and the punch body 222 in which the punch 220 is elevated and lowered, and a low coefficient of friction Made of a material of, and consists of a punch head 221 in contact with the sheet-shaped base material (900).

That is, in order to reinforce the overall rigidity of the punch 220, the punch body 222 in which the punch is elevated and lowered is formed of alloy tool steel, and only the portion of the punch head 221 in direct contact with the sheet-shaped base material 900 is reduced. It can be composed of a material with a coefficient of friction.

Except for this structure, the rest of the structure is the same as the structure of the embodiment described with reference to FIG. 2, and a description thereof will be omitted.

Although the above description has been made with reference to the drawings according to the embodiments of the present invention, a person of ordinary skill in the field to which the present invention belongs will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

Claims (5)

An apparatus for molding a battery case including an electrode assembly receiving portion in which an electrode assembly may be embedded,
A die in which an indented or through-type open groove having a size corresponding to the electrode assembly receiving portion is formed, and a sheet-like base material for manufacturing a battery case is positioned on an upper surface;
As a punch having a shape corresponding to the open groove, it is located above the open groove for deep drawing on the sheet-like base material, and a punch head to be introduced into the open groove when descending has a low coefficient of friction ( a punch made of a material of frictional coefficient); And
Includes a stripper for pressing and fixing both ends of the sheet-like base material to a die for deep drawing,
The sheet-like base material is a laminate sheet including a resin layer and a metal layer,
The punch,
Punch body made of alloy tool steel and the vertical movement of the punch; And
It is formed at the lower end of the body, is made of a material having a low coefficient of friction, and is made of a punch head that contacts the sheet-like base material
The punch head is made of polytetrafluoroethylene, a battery case molding apparatus, characterized in that the coefficient of friction is 0.04 to 0.2. delete delete delete delete

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