KR101592196B1 - Laminate Sheet Including Complex Membrane of Polymer Having Different Material Properties - Google Patents

Abstract

The present invention relates to a laminate sheet comprising an outer coating layer having a weather-resistant polymer composite membrane having different physical properties, an inner sealant layer containing a heat-sealable polymer, and a barrier layer interposed between the outer coating layer and the inner sealant layer. Lt; / RTI >

Description

(Laminate Sheet Including Complex Membrane of Polymer Having Different Material Properties) having a polymer composite membrane having different physical properties,

The present invention relates to a laminate sheet comprising a polymer composite membrane having different physical properties.

As technology development and demand for mobile devices are increasing, the demand for secondary batteries as energy sources is rapidly increasing. Among such secondary batteries, many studies have been made on lithium secondary batteries having high energy density and discharge voltage, Widely used.

Generally, a secondary battery includes an electrode assembly composed of a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, which is laminated or wrapped in a battery case of a metal can or a laminate sheet and then injected or impregnated with an electrolyte solution have.

Among these secondary batteries, a pouch type secondary battery comprising a high-capacity and high-output battery cell has a problem in that the SEI film is difficult to maintain as the internal temperature rises during charging and discharging, a large amount of gas is generated, There is a problem that the whole battery is damaged.

Accordingly, there is a need to develop a new lithium secondary battery for solving the above 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.

An object of the present invention is to provide a laminate sheet in which the surface area in contact with the outside air increases when the internal pressure and the temperature rise.

In order to achieve the above object, according to the present invention, there is provided a laminated sheet comprising:

An outer coating layer having a weather-resistant polymer composite membrane having different physical properties;

An inner sealant layer comprising a heat sealable polymer; And

A barrier layer interposed between the outer coating layer and the inner sealant layer;

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That is, the laminate sheet according to the present invention has a polymer composite membrane having different physical properties, so that when the internal pressure and temperature rise, the surface area in contact with the outside air can be increased.

Specifically, the outer coating layer may comprise a composite film in which polymers having different physical properties such as rigidity, thermal expansion coefficient, and vitrification temperature are mixed together. Therefore, depending on the applied pressure and temperature, the heterogeneous polymers are deformed to different degrees, whereby the surface of the outer coating layer is deformed into a curved shape, so that the surface area in contact with the outside air can be increased.

The inner sealant layer may further include a thermally fusible polymer composite membrane having different physical properties.

The barrier layer is a metal layer, and the metal layer may have unevenness formed on one surface and / or both surfaces.

Specifically, the metal layer may be aluminum, iron, copper, tin, nickel, cobalt, silver, stainless steel, titanium, or an alloy thereof, but is not limited thereto.

The outer coating layer may be formed of a single-layer polymer composite film in which polymers having different physical properties form regular or irregular patterns.

The outer coating layer may include a first polymer forming a part of the single-layer polymer composite film and a second polymer forming another part of the first polymer.

The inner sealant layer may be composed of a single-layer polymer composite membrane in which polymers having different physical properties are regularly or irregularly arranged.

The inner sealant layer may include a first polymer forming part of the polymer composite membrane of a single layer and a second polymer forming another part of the first polymer.

The outer coating layer may be composed of a polymer composite film having a polymer multi-layer having different physical properties from each other.

The inner sealant layer may be composed of a polymer composite membrane having a polymer multi-layer having different physical properties from each other.

The polymers having different physical properties may be polymers having different vitrification temperatures, thermal expansion coefficients, or mechanical expansion coefficients, but are not limited thereto.

The present invention also provides a battery case including the laminate sheet.

The battery case may include a first case including a housing portion for housing the electrode stack body and the electrolyte, a remainder extending from the housing portion, and a second case coupled to the first case to seal the battery case have.

The second case may include a housing portion for housing the electrode stack body and the electrolyte, and a remaining portion extending from the housing portion.

The second case may extend from a part of the remaining portion of the first case.

The first case and the second case may be independent members separated from each other.

The present invention also provides a battery comprising the battery case, the electrolyte, and the electrode laminate.

The battery may be a lithium ion battery, a lithium polymer battery, or a lithium ion polymer battery.

The electrode may be a positive electrode or a negative electrode, and may be manufactured by a manufacturing method including the following processes.

In the electrode manufacturing method,

Dispersing or dissolving the binder in a solvent to prepare a binder solution;

Preparing an electrode slurry by mixing the binder solution, the electrode active material, and the conductive material;

Coating the electrode slurry on a current collector;

Drying the electrode; And

And compressing the electrode to a predetermined thickness.

In some cases, the rolled electrode may further be dried.

The binder solution preparation process is a process of dispersing or dissolving the binder in a solvent to prepare a binder solution.

The binder may be any binder known in the art and specifically includes polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE) A binder such as a fluorocarbon resin binder, a styrene-butadiene rubber, an acrylonitrile-butadiene rubber, a styrene-isoprene rubber, a carboxymethylcellulose (CMC), starch, hydroxypropylcellulose and regenerated cellulose One or more binders selected from the group consisting of a cellulose-based binder, a polyalcohol-based binder, a polyolefin-based binder including polyethylene, polypropylene, a polyimide-based binder, a polyester-based binder, a mussel adhesive, and a silane-based binder Mixtures or copolymers.

The solvent can be selectively used depending on the type of the binder. For example, organic solvents such as isopropyl alcohol, N-methylpyrrolidone (NMP), and acetone and water can be used.

As a specific example of the present invention, a binder solution for a positive electrode may be prepared by dispersing / dissolving PVdF in NMP (N-methyl pyrrolidone), or a styrene-butadiene rubber (SBR) / carboxy methyl cellulose (CMC) To prepare a negative electrode binder solution.

An electrode active material and a conductive material may be mixed / dispersed in the binder solution to prepare an electrode slurry. The electrode slurry thus prepared can be transferred to a storage tank and stored until the coating process. In order to prevent the electrode slurry from hardening in the storage tank, the electrode slurry can be agitated continuously.

The electrode active material may be a positive electrode active material or a negative electrode active material.

Specifically, 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 + y} Mn _2-y O ₄ (where y is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ and LiMnO ₂ ; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; Formula _{LiNi 1-y M y O 2} ( where, the M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, y = 0.01 ~ 0.3 Im) Ni site type lithium nickel oxide which is represented by; Formula _{LiMn 2-y M y O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, y = 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.

In a non-limiting embodiment of the present invention, the electrode active material may include a lithium metal oxide having a spinel structure represented by the following chemical formula (1) as a cathode active material.

Li _x M _y Mn _{2 - y} O _{4 - z z} (1)

Wherein 0 < y < 2, 0 z < 0.2,

M is at least one element selected from the group consisting of Al, Mg, Ni, Co, Fe, Cr, V, Ti, Cu, B, Ca, Zn, Zr, Nb, Mo, Sr, Sb, W, ;

A is one or more of an anion of -1 or -2.

The maximum substitution amount of A may be less than 0.2 mol%. In a specific embodiment of the present invention, A may be at least one anion selected from the group consisting of halogens such as F, Cl, Br, I, S and N.

By substituting these anions, the binding force with the transition metal is improved and the structural transition of the compound is prevented, so that the lifetime of the battery can be improved. On the other hand, if the substitution amount of the anion A is too large (t? 0.2), the life characteristic is deteriorated due to the incomplete crystal structure, which is not preferable.

Specifically, the oxide of the formula (1) may be a lithium metal oxide represented by the following formula (2).

Li _x Ni _y Mn _2-y O ₄ (4)

In the above formula, 0.9? X? 1.2 and 0.4? Y? 0.5.

More specifically, the lithium metal oxide may be LiNi _0.5 Mn _1.5 O ₄ or LiNi _0.4 Mn _1.6 O ₄ .

Examples of the negative electrode active material include carbon such as non-graphitized carbon and 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 &lt; 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, Bi ₂ O ₅ and the like; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials, and the like.

In a non-limiting embodiment of the present invention, the electrode active material may include a lithium metal oxide as a negative electrode active material, and the lithium metal oxide may preferably be represented by the following chemical formula (3).

Li _a M ' _b O _{4-ca c} (3)

In the above formula, M 'is at least one element selected from the group consisting of Ti, Sn, Cu, Pb, Sb, Zn, Fe, In, Al and Zr;

a and b are 0.1? a? 4; Is determined according to the oxidation number of M 'in the range of 0.2? B? 4;

c is determined according to the oxidation number in the range of 0? c <0.2;

A is one or more of an anion of -1 or -2.

The oxide of the formula (3) may be represented by the following formula (4).

Li _a Ti _b O ₄ (4)

        In the above formula, 0.5? A? 3, 1? B? 2.5.

The lithium metal oxide may be Li _0.8 Ti _2.2 O ₄ , Li _2.67 Ti _1.33 O ₄ , LiTi ₂ O ₄ , Li _1.33 Ti _1.67 O ₄ , Li _1.14 Ti _1.71 O _4, or the like. However, the present invention is not limited to these.

In a non-limiting embodiment of the present invention, the lithium metal oxide may be Li _1.33 Ti _1.67 O ₄ or LiTi ₂ O ₄ . Li _1.33 Ti _1.67 O ₄ has a spinel structure with less change in crystal structure during charging and discharging and excellent reversibility.

The lithium metal oxide can be produced by a production method known in the art and can be produced by, for example, a solid phase method, a hydrothermal method, a sol-gel method, or the like.

The lithium metal oxide may be in the form of secondary particles in which primary particles are aggregated.

The particle size of the secondary particles may be 200 nm to 30 탆.

If the particle diameter of the secondary particles is less than 200 nm, a large amount of solvent is required in the negative electrode slurry production process, which lowers productivity and is not preferable because it is difficult to control the moisture content. When the particle diameter of the secondary particles is more than 30 占 퐉, the diffusion rate of lithium ions is slow and it is difficult to realize a high output, which is not preferable.

The lithium metal oxide may be contained in an amount of 50 wt% or more to 100 wt% or less based on the weight of the entire negative electrode active material.

When the content of lithium titanium oxide is 100 wt% with respect to the weight of the entire negative electrode active material, it means that the negative active material is composed of lithium titanium oxide alone.

The conductive agent is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples thereof include graphite such as natural graphite and 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.

A filler or the like may be optionally added to the electrode slurry as required. The filler is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery, and examples thereof include olefin-based polymerizers such as polyethylene and polypropylene; Fibrous materials such as glass fiber, carbon fiber and the like can be used.

The process of coating the electrode slurry on the current collector is a process in which the electrode slurry is passed through a coater head to coat the current collector with a predetermined pattern and a constant thickness.

The method of coating the electrode slurry on the current collector may include a method of uniformly dispersing the electrode slurry on a current collector using a doctor blade or the like, a die casting method, a comma coating method ), Screen printing, and the like. Alternatively, the electrode slurry may be bonded to the current collector by molding on a separate substrate, followed by pressing or lamination.

The current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery. For example, the current collector may be made of 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. The positive electrode current collector may be formed into various shapes such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven fabric, or the like by forming fine irregularities on the surface to enhance the bonding force of the positive electrode active material. Specifically, the cathode current collector may be a metal current collector including aluminum, and the anode current collector may be a metal current collector including copper. The electrode current collector may be a metal foil, and may be an aluminum foil or a copper foil.

The drying process is a process of removing the solvent and moisture in the slurry to dry the slurry coated on the metal current collector. In a specific example, the drying process is performed within one day in a vacuum oven at 50 to 200 ° C.

After the drying process, a cooling process may be further included, and the cooling process may be a slow cooling process to room temperature to form a recrystallized structure of the binder.

In order to increase the capacity density of the coated electrode and increase the adhesion between the current collector and the active materials, an electrode can be passed between two rolls heated at a high temperature and compressed to a desired thickness. This process is called the rolling process.

The electrode can be preheated before passing the electrode between two heated, heated rolls. The preheating process is a process of preheating the electrode before it is introduced into the roll to increase the compression effect of the electrode.

The electrode having completed the rolling process as described above can be dried within one day in a vacuum oven at 50 to 200 DEG C in a range satisfying a temperature equal to or higher than the melting point of the binder. The rolled electrode may be cut to a certain length and then dried.

After the drying process, a cooling process may be further included, and the cooling process may be a slow cooling process to room temperature to form a recrystallized structure of the binder.

The polymer membrane is a separator separating the anode and the cathode. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.

The separator is made of an insulating thin film having high ion permeability and mechanical strength. 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; Kraft paper and the like are used. Representative examples currently on the market include the Celgard ^R 2400, 2300 (from Hoechest Celanese Corp.), polypropylene separator (from Ube Industries Ltd. or Pall RAI), and polyethylene series (from Tonen or Entek).

In some cases, a gel polymer electrolyte may be coated on the separation membrane to increase the stability of the cell. Representative examples of such a gel polymer include polyethylene oxide, polyvinylidene fluoride, and polyacrylonitrile.

The electrode laminate may include both a jelly-roll type electrode assembly (or a wound electrode assembly), a stacked electrode assembly (or a stacked electrode assembly), or a stacked & folded electrode assembly having a structure known in the art.

In this specification, the stacked & folded type electrode assembly is a method of arranging unit cells having a structure in which a separator is interposed between an anode and a cathode on a separator sheet, folding and winding the separator sheet A stack &amp; folding type electrode assembly.

The electrode laminate may include an electrode laminate having a structure in which one of an anode and a cathode is laminated by a method of being laminated in a structure in which they are interposed between the separators by thermal fusion or the like.

As the non-aqueous electrolyte, a nonaqueous electrolyte, a solid electrolyte, an inorganic solid electrolyte, or the like is used.

Examples of the nonaqueous electrolyte include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate , Gamma -butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, Diethyl ether, formamide, dimethyl formamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane A non-protonic organic solvent such as an ether, a methyl pyrophosphate, or an ethyl propionate is used as the solvent, a sulfone, a methyl sulfolane, a 1,3-dimethyl-2-imidazolidinone, a propylene carbonate derivative, a tetrahydrofuran derivative, .

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, Polymers containing ionic dissociation groups, and the like can 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, LiSCN, LiC (CF 3 SO 2) 3, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, 4-phenylborate, imide, and the like can be used.

For the purpose of improving the charge-discharge characteristics and the flame retardancy, the electrolytic solution may contain at least one selected from the group consisting of pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, n-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, 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), FPC (fluoro-propylene carbonate), and the like.

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

The present invention also provides a device using the battery pack as an energy source.

The device may be selected from the group consisting of a cell phone, a portable computer, a smart phone, a smart pad, a netbook, a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, .

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

INDUSTRIAL APPLICABILITY As described above, the laminate sheet according to the present invention includes the polymer composite membrane having different physical properties, so that when the internal pressure and the temperature rise, the surface area in contact with the outside air can be increased.

1 is a schematic view of a laminate sheet according to one embodiment of the present invention;
2 is a schematic view of a laminated sheet according to another embodiment of the present invention.

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

1 is a schematic view of a laminated sheet according to an embodiment of the present invention.

Referring to FIG. 1, a laminate sheet 10 includes an outer coating layer 110, a barrier layer 120, and an inner sealant layer 130.

The outer coating layer 110 is formed on the upper surface of the barrier layer 120 and the inner sealant layer 130 is formed on the lower surface of the barrier layer 120.

The outer coating layer 110 is composed of a single layer, and both sides of the single layer are composed of the first polymer 111 and the middle portion is composed of the second polymer 112.

The inner sealant layer 130 is composed of a single layer, and both sides of the single layer are composed of the first polymer 131 and the middle portion is composed of the second polymer 132.

2 is a schematic view of a laminate sheet 20 according to another embodiment of the present invention.

Referring to FIG. 2, the outer coating layer 210 has a top portion composed of a first polymer 211 and a bottom portion formed of a second polymer 212.

The upper portion of the inner sealant layer 230 is composed of the first polymer 231 and the lower end of the inner sealant layer 230 is composed of the second polymer 232. The remaining structures except for the formation positions of the polymers are the same as those of the embodiment described in FIG. 1, so that detailed description thereof will be omitted.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

Claims (20)

An outer coating layer having a weather-resistant polymer composite membrane having different physical properties;
An inner sealant layer comprising a heat sealable polymer; And
A barrier layer interposed between the outer coating layer and the inner sealant layer;
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Wherein the outer coating layer comprises a first polymer comprising a polymer composite membrane of a single layer in which polymers having different physical properties form a regular or irregular pattern and forming a part of a polymer composite membrane of a single layer, And a second polymer forming another part of the laminate sheet. The laminate sheet according to claim 1, wherein the inner sealant layer comprises a heat-sealable polymer composite membrane having different physical properties. The laminate sheet according to claim 1, wherein the barrier layer is a metal layer, and the metal layer has irregularities on one surface, both surfaces, or one surface and both surfaces. The laminate sheet according to claim 3, wherein the metal layer is one or an alloy selected from the group consisting of aluminum, iron, copper, tin, nickel, cobalt, silver, stainless steel and titanium. delete delete The laminate sheet according to claim 2, wherein the inner sealant layer comprises a single-layer polymer composite membrane in which polymers having different physical properties are regularly or irregularly arranged. The laminate according to claim 7, wherein the inner sealant layer comprises a first polymer forming a part of a polymer composite membrane of a single layer and a second polymer forming another part of the polymer composite membrane of the single layer Sheet. delete The laminate sheet according to claim 2, wherein the inner sealant layer is formed of a polymer composite film having a polymeric multilayer having different physical properties from each other. The polymer of claim 1 or 2, wherein the polymer having different physical properties contained in the outer coating layer is a polymer having a different vitrification temperature, a thermal expansion coefficient or a mechanical expansion coefficient, and a thermally fusible polymer Is a polymer having a vitrification temperature, a thermal expansion coefficient or a mechanical expansion coefficient different from each other. A battery case comprising a laminate sheet according to any one of claims 1 to 4, 7, 8 and 10. The battery case according to claim 12, wherein the battery case includes: a first case including a housing part for housing the electrode stack body and the electrolyte, and a remainder extending from the housing part; and a second case The battery case according to claim 1, further comprising a case. The battery case according to claim 13, wherein the second case includes a housing part for housing the electrode stack body and the electrolyte, and a remaining part extending from the housing part. 14. The battery case according to claim 13, wherein the second case extends from a part of the remaining portion of the first case. 14. The battery case according to claim 13, wherein the first case and the second case are independent members separated from each other. A battery case according to claim 12;
Electrolyte; And
Electrode laminate;
And a battery. 18. The battery according to claim 17, wherein the battery is one selected from the group consisting of a lithium ion battery, a lithium polymer battery, and a lithium ion polymer battery. A battery pack comprising the battery according to claim 18. A device using the battery pack according to claim 19 as a power source.

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