KR20160133771A - Electrode lead or aluminum pouch for secondary battery with improved thermal resistance and secondary battery comprising same - Google Patents

Abstract

The present invention relates to an electrode lead or aluminum pouch for a secondary battery with improved heat resistance, and a secondary battery including the same. Provided is an electrode lead or aluminum pouch for a secondary battery, coated with a fire-retardant film including a fire-retardant polymer or fire-retardant additive. According to an embodiment of the present invention, as the surface of the electrode lead or aluminum pouch is coated with the fire-retardant film including a fire-retardant polymer or fire-retardant additive, the present invention is capable of improving heat resistance of the secondary battery by protecting a cell from a cause for ignition such as an external fire, flames, or spark.

Description

TECHNICAL FIELD [0001] The present invention relates to an electrode lead or an aluminum pouch for a secondary battery having improved heat resistance, and a secondary battery including the electrode lead or the aluminum pouch. [0002]

The present invention relates to an electrode lead or an aluminum pouch for an improved secondary battery, and a secondary battery comprising the same. More particularly, the present invention relates to an electrode lead or an aluminum pouch used for a secondary battery, To an electrode lead or an aluminum pouch for an improved secondary battery, and an improved secondary battery including the same.

Recently, interest in energy storage technology is increasing. As the application fields of cell phones, camcorders, notebook PCs and even electric vehicles are expanding, efforts for research and development of electrochemical devices are becoming more and more specified. Electrochemical devices have attracted the greatest attention in this respect, among which the development of rechargeable secondary batteries has become a focus of attention. In recent years, in order to improve the capacity density and specific energy in developing such batteries, And research and development on the design of the battery.

Among the currently applied secondary batteries, the lithium secondary battery developed in the early 1990s has advantages such as higher operating voltage and higher energy density than conventional batteries such as Ni-MH, Ni-Cd and sulfuric acid-lead batteries using an aqueous electrolyte solution .

The secondary battery can be classified according to the structure of the electrode assembly having the anode / separator / cathode structure. Typically, a jelly-roll type electrode assembly having a structure in which a long sheet-like anode and a cathode are wound with a separator interposed therebetween, a stacked structure in which a plurality of anodes and cathodes cut in a predetermined size unit are sequentially stacked with a separator interposed therebetween A stack / folding type electrode assembly having a structure in which a bi-cell or full-cell stacked with a predetermined unit of positive and negative electrodes stacked with a separator interposed therebetween is wound up.

The pouch for a secondary cell is used as a casing for packaging the secondary battery. The pouch for the secondary battery protects the battery cell made of the electrolyte introduced into the electrode assembly and the subsequent process, and is a complement to the electrochemical properties of the battery cell. The aluminum foil may be made of polyethylene terephthalate (PET) resin, polyethylene naphthalate (PET) resin, or the like, in order to protect the battery cell from external impacts. , PEN), nylon resin, or liquid crystal polymer (LCP) forms an outer layer.

In particular, PET, which is an aluminum thin film, is used in many fields as a high performance material having high rigidity, flexibility, resistance to tearing and stretching, thermal stability and chemical resistance. However, PET has a disadvantage that it is very vulnerable to fire due to high flammability and dripping during combustion. In particular, when combustion is started by the nearby ignition sources, very poisonous gas is generated during rapid ignition and combustion, which may cause secondary damage in case of fire.

BACKGROUND ART In many fields, a technique of adding a flame retardant to a part of a material for the purpose of preventing and suppressing ignition is widely used. For example, a flame retardant added to a plastic composite suppresses ignition by generating a fire-extinguishing gas or melting and forming a film that blocks oxygen on the surface of the composite. Thus, the use of flame retardants in terms of ignition prevention and inhibition has proven to be very effective.

In the field of batteries, many methods have been proposed for preventing and suppressing ignition through the use of such a flame retardant. For example, JP-A-8-84870 discloses a method of adding phosphoric acid ester to an electrolytic solution, and Japanese Patent Laid-Open Publication No. 1999-154535 discloses a method of incorporating ammonium phosphate into a cathode or an electrode. Although these methods actually provide excellent ignition inhibiting ability, they are directly added to the main functional elements of the battery, so that deterioration of the battery performance can not be avoided.

Therefore, it is necessary to develop a technology capable of maintaining the main performance of the battery while enhancing the safety of the secondary battery by having resistance to external fire and ignition source.

SUMMARY OF THE INVENTION The present invention provides an electrode lead or an aluminum pouch for a secondary battery having improved heat resistance that can protect a battery when the battery is exposed to an external fire or an ignition source.

In addition, the present invention provides a secondary battery having improved heat resistance including the electrode lead or the aluminum pouch.

According to an aspect of the present invention, there is provided an electrode lead for a secondary battery, wherein the electrode lead is coated with a flame retardant film including a flame retardant polymer or a flame retardant additive.

According to an aspect of the present invention, there is provided an aluminum pouch for a secondary battery, wherein the aluminum pouch is coated with a flame retardant film containing a flame retardant polymer or a flame retardant additive.

According to an aspect of the present invention, there is also provided a heat-resistant secondary battery including the above-described electrode lead and / or aluminum pouch.

According to the present invention, the flame retardant film including the flame retardant polymer or the flame-retardant additive is coated on the surface of the electrode lead or the aluminum pouch for the secondary battery, thereby improving the heat resistance of the secondary battery by protecting the cell from external ignition sources such as fire, .

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments of the invention and, together with the description of the invention, It should not be construed as limited.
1 is a view illustrating an electrode lead of a conventional secondary battery.
FIG. 2 is a view illustrating an electrode lead for a secondary battery including a flame-retardant film including a flame-retardant polymer or a flame-retardant additive according to an embodiment of the present invention.
3 is a view showing a sectional structure of an aluminum pouch of a conventional secondary battery.
4 is a cross-sectional view of an aluminum pouch for a secondary battery in which a flame-retardant film including a flame-retardant polymer or a flame-retardant additive according to an embodiment of the present invention is applied instead of a PET film portion of an aluminum pouch.
5 is a cross-sectional view of an aluminum pouch for a secondary battery in which a flame-retardant film containing a flame-retardant polymer or a flame-retardant additive according to an embodiment of the present invention is applied to an upper surface of a PET film of an aluminum pouch.

Hereinafter, the present invention will be described in detail with reference to the drawings. The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

The present invention provides an electrode lead for a secondary battery, wherein the electrode lead for a secondary battery is coated with a flame retardant film containing a flame retardant polymer or a flame retardant additive.

The film containing the flame retardant polymer according to the present invention may be formed on at least one of the negative electrode lead and the positive electrode lead. That is, a flame retardant film layer is formed only in a portion of the negative electrode lead that is exposed to the outside of the aluminum pouch. The positive electrode lead may be formed by forming a flame retardant film layer on both the exposed portion of the aluminum pouch and the unexposed portion, The flame retardant film layer may be formed only on a portion exposed to the outside of the aluminum pouch and the negative electrode lead may be formed on both the exposed portion and the unexposed portion of the aluminum pouch. Preferably, in order to prevent the resistance of the secondary battery from increasing, both the positive electrode lead and the negative electrode lead can be formed only in the portion of the aluminum pouch exposed to the outside.

As illustrated in FIG. 1, a conventional electrode lead is composed of a lead metal part 10 and a polypropylene (PP) film 11.

In the present invention, the PP film (11) of the electrode lead can be replaced with a flame retardant film (14) containing a flame retardant polymer or a flame retardant additive.

Further, in the aluminum pouch for a secondary battery according to the present invention, the aluminum pouch for a secondary battery is characterized in that the surface of the aluminum film is coated with a flame retardant film containing a flame retardant polymer or a flame retardant additive.

In general, the aluminum pouch for a secondary battery is composed of a polypropylene (PP) film 11, an aluminum film 20 and a polyethylene terephthalate (PET) film 13, as illustrated in Fig.

According to the present invention, the flame-retardant film 14 may be applied instead of the PET film (see FIG. 4) or the flame-retardant film 14 may be applied on the surface of the PET film layer (see FIG. 5). Thus, by placing the flame retardant film containing the flame retardant polymer or the flame retardant additive on the outermost periphery of the aluminum pouch, it is possible to have resistance to heat on the outer surface of the secondary battery.

According to the present invention, the flame retardant film containing the flame retardant polymer or the flame retardant additive is formed on the surface of the electrode lead or the aluminum pouch of the secondary battery to improve the heat stability of the battery by protecting the cell from external ignition sources such as fire, spark, .

Meanwhile, the flame-retardant film according to the present invention may be formed on one side or both sides of the electrode lead or the aluminum pouch. The flame retardant film containing the flame retardant polymer or the flame retardant additive may be formed through coating or plating, and may be formed using a method of electroplating.

The kind of the flame retardant polymer or the flame retardant additive contained in the flame retardant film of the present invention is not particularly limited and, for example, halogen-based or phosphorus-based may be used, and in some cases, .

The halogen system generally exhibits a flame retarding effect by substantially stabilizing the radicals generated in the gas phase. Examples of the halogen-based flame retardant include tribromophenoxyethane, tetrabromobisphenol-A (TBBA), octabromophenylether (OBDPE), brominated epoxy oligomer, brominated polycarbonate oligomer, chlorinated paraffin, chlorinated polyethylene, alicyclic Chlorine-based flame retardants and the like.

Phosphorus generally produces a polymetaphosphoric acid by pyrolysis and forms a protective layer or a carbon film produced by the dehydration action when polymetaphosphoric acid is produced blocks oxygen, thereby exhibiting a flame retarding effect. Examples of phosphorus-based flame retardants include phosphates such as ammonium phosphates, phosphine oxides, phosphine oxide diols, phosphites, phosphonates, triaryl phosphates, alkyldiaryl phosphates, trialkyl phosphates, and resorcinol bisdiphenyl phosphates (RDP).

In addition, inorganic compound flame retardants can also be used. Generally, they are decomposed by heat to release incombustible gases such as water, carbon dioxide, sulfur dioxide, and hydrogen chloride to induce an endothermic reaction, thereby preventing the access of oxygen by diluting the combustible gas, The reaction is cooled and the production of pyrolysis products is reduced, thereby exhibiting a flame retarding effect. Examples of such inorganic compound flame retardants include aluminum hydroxide, magnesium hydroxide, antimony oxide, tin hydroxide, tin oxide, molybdenum oxide, zirconium compounds, borate salts, calcium salts and the like.

Among the above flame retardants, ammonium flame retardants based on phosphates may be particularly preferably used. In some cases, it may further include other additives that induce a flame-retarding synergistic effect when mixed with the above-mentioned flame retardant.

The substrate of the flame retardant film containing the flame retardant is not particularly limited as long as it can stably maintain the flame retardant without inducing any chemical action inside the cell itself. Examples of such a film substrate include polyethylene, polypropylene, polyurethane, fluorine-based polymer and the like, preferably polyurethane which exhibits flame retardancy by itself.

In the flame retardant film, the content of the flame retardant polymer or the flame retardant additive is preferably 20 to 90% by weight based on the total weight of the flame retardant film. The flame retardant polymer or the flame retardant additive may be present in the form contained in the interior of the film substrate or may be present in the form coated on the outer surface of the film.

The flame-retardant film can be produced by a simple manufacturing method. For example, when a thermoplastic resin is used as a film substrate, it can be produced by blending a flame retardant into a melt of a thermoplastic resin, and then shaping it into a film to solidify it. When a thermosetting resin is used as a film substrate, the thermosetting resin is dissolved in a solvent and mixed with a flame retardant to form a film, and then the solvent is removed, or a flame retardant is added to the thermosetting resin A polymer in the form of a flame retardant-containing flame retardant may be produced in the form of a film. The flame retardant may be coated on one side or both sides of the produced film by various methods. In addition, it is also possible to produce a composite type in which a flame retardant is contained in the inside and the outside of the film substrate by using a combination of the above methods.

The thickness of the flame retardant film containing the flame retardant polymer or the flame retardant additive according to the present invention is not particularly limited. However, it may be formed in a range of 1 nm to 500 탆 in order to effectively protect the electrode lead and the aluminum pouch while preventing the electrode lead and the aluminum pouch from becoming too thick.

The present invention also provides a secondary battery comprising the above-described electrode lead having the flame retardant film formed thereon and / or the aluminum pouch described above.

The secondary battery of the present invention includes an electrode assembly including a cathode, a cathode, and a separator, an aluminum pouch for housing the electrode assembly, and the electrode lead electrically connected to the electrode assembly.

Here, the secondary battery may be a lithium secondary battery, specifically, a pouch type lithium secondary battery including an adhesive film (i.e., an "insulating film") for insulating the electrode lead from the casing.

The positive electrode, negative electrode, separator, electrolyte, pouch, cover and the like used in the present invention can be easily produced by processes and / or methods known in the art. The positive electrode, the negative electrode, and the separator constituting the electrode assembly may be those conventionally used for manufacturing a lithium ion secondary battery.

Specifically, the anode is prepared, for example, by coating a mixture of a cathode active material, a conductive agent and a binder on a cathode current collector, followed by drying, and if necessary, further adding a filler to the mixture.

The cathode active material according to the present invention is 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; A lithium manganese oxide (LiMnO ₂ ) such as LiMnO ₃ , LiMn ₂ O ₃ , LiMnO _2, etc. represented by the formula Li _{1 + x} Mn _{2 -x} O ₄ (where x is 0 to 0.33); 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 nickel-situ type lithium nickel oxide represented 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) oxide); 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 part of the lithium in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) _3, or a composite oxide formed by a combination of these materials, and the like, may be mixed with a compound containing a lithium intercalation material as a main component.

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 change in the battery, and may be formed of a material such as stainless steel, aluminum, nickel, titanium, sintered carbon, or a surface of aluminum or stainless steel 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 conductive agent is usually added in an amount of 1 to 50% by weight based on the total weight of the mixture including the cathode active material. Such a conductive agent is not particularly limited as long as it has electrical conductivity without causing a chemical change 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 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 binding of the active material and the conductive agent and bonding to the current collector, and is usually added in an amount of 1 to 50% 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.

The negative electrode is manufactured by applying a negative electrode material on a negative electrode collector and drying the same, and may further include the above-described components as needed.

The negative electrode 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 conductivity without causing chemical change in the battery, and may be formed of a material such as copper, stainless steel, aluminum, nickel, titanium, fired carbon, 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 material includes amorphous carbon or regular carbon, and specifically carbon such as hard 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 < 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.

A polyolefin-based separator commonly known as a separator for insulating the electrodes between the anode and the cathode or a composite separator having an organic-inorganic composite layer formed on the olefin-based substrate may be used without particular limitation.

An electrode assembly having the above structure is housed in an aluminum pouch, and then an electrolytic solution is injected to manufacture a battery.

The electrolyte according to the present invention is a lithium salt-containing non-aqueous electrolyte, which is composed of a nonaqueous electrolyte and lithium. As the non-aqueous electrolyte, a non-aqueous electrolyte, a solid electrolyte, an inorganic solid electrolyte and the like are used.

Examples of the nonaqueous electrolytic solution include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, But are not limited to, lactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, Nitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives , Tetrahydrofuran derivatives, ethers, methyl propionate, 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, 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, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, 4-phenyl lithium borate, and imide .

For the purpose of improving charge / discharge characteristics, flame retardancy, etc., non-aqueous electrolytes may be used in the form of, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride and the like are added It is possible. 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.

It should be noted that the embodiments of the present invention disclosed herein are merely examples of specific examples for the purpose of understanding and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

In this specification, terms indicating directions such as up and down, right and left, forward and backward and the like are used, but these terms are relative positions only for the sake of convenience of explanation and may vary depending on the observation position of the observer and the arrangement form of each component Will be apparent to those skilled in the art.

10: lead metal part
11: PP film
13: PET film
14: Flame retardant film
20: Aluminum film

Claims (13)

In the electrode lead for a secondary battery,
Wherein the electrode lead is coated with a flame retardant film containing a flame retardant polymer or a flame retardant additive. The method according to claim 1,
Wherein the flame retardant polymer comprises a halogen-based flame retardant polymer or a phosphorus-based flame retardant polymer. The method according to claim 1,
Wherein the flame retardant additive comprises a halogen flame retardant additive or a phosphorus flame retardant additive. The method according to claim 1,
Wherein the flame retardant film is coated on one or both surfaces of the electrode lead. The method according to claim 1,
Wherein the flame retardant film has a thickness in the range of 1 nm to 500 占 퐉. In an aluminum pouch for a secondary battery,
Characterized in that the aluminum pouch is coated with a flame retardant film containing a flame retardant polymer or a flame retardant additive. The method according to claim 6,
Wherein the flame retardant polymer comprises a halogen-based flame retardant polymer or a phosphorus-based flame retardant polymer. The method according to claim 6,
Wherein the flame retardant additive comprises a halogen flame retardant additive or a phosphorus flame retardant additive. The method according to claim 6,
Wherein the flame retardant film is formed on one or both surfaces of the aluminum pouch. The method according to claim 6,
Wherein the flame retardant film has a thickness in the range of 1 nm to 500 占 퐉. A heat-resistant secondary battery comprising the electrode lead according to any one of claims 1 to 5. A heat-resistant secondary battery comprising the aluminum pouch according to any one of claims 6 to 10. An electrode lead according to any one of claims 1 to 5, and
A heat-resistant secondary battery comprising the aluminum pouch according to any one of claims 6 to 10.

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