KR101025415B1 - Case for electrochemical device, preparation method thereof, and electrochemical device comprsing the same - Google Patents

Abstract

The present invention relates to a case for an electrochemical device having at least one component layer, comprising a component, a coating component, or a component and a coating component constituting the component layer of the packaging material, higher than the normal operating temperature range of the device. An electrochemical device exterior material, a method of manufacturing the same, and an electrochemical device provided with the exterior material, which contain a blowing agent that releases a gas other than oxygen at a temperature T.

The present invention can significantly improve the safety that has been pointed out as a problem of the conventional lithium secondary battery by using the foaming agent as a coating component or component of the exterior material.

Electrochemical device, exterior material, foaming agent, safety, lithium secondary battery

Description

Exterior material for electrochemical device, manufacturing method thereof, and electrochemical device having same {CASE FOR ELECTROCHEMICAL DEVICE, PREPARATION METHOD THEREOF, AND ELECTROCHEMICAL DEVICE COMPRSING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exterior material and an electrochemical device having the exterior material that can provide excellent safety even when the internal temperature of the device is abnormally increased due to external or internal factors, and more particularly, releases a large amount of inert gas at a high temperature. By using a blowing agent in the exterior material, it prevents contact with oxygen necessary for ignition and enables early venting to open the heat-sealed portion of the exterior material by increasing the internal pressure due to the released gas, thereby controlling the temperature rise or controlling the internal temperature from rising. The present invention relates to an exterior material that can prevent explosion and / or ignition in advance during overcharge and high temperature storage by releasing vaporized flammable electrolyte gas to the outside, and a manufacturing method thereof, and an electrochemical device having improved safety by having the exterior material.

In general, a lithium secondary battery using a flammable non-aqueous electrolyte is rapidly ignited due to a variety of causes, the safety is drastically reduced. Among the many known causes, the first reaction is due to the contraction of the separator, which is interposed between the positive and negative electrodes to prevent the short of the positive electrode. Currently, polyethylene membranes which are most used start to melt in the range of 120 to 130 ° C., and thus are accompanied by shrinkage of the membranes, and thus short-circuiting occurs due to contact between the cathode and the anode at the corners, resulting in thermal energy generated by a large amount of current flow. The internal temperature of the battery is continuously increased due to the supply of, and thus the battery is ignited while reaching the temperature at which the electrolyte decomposes.

In order to solve this problem, a solution through the organic electrolyte additive has been proposed. For example, U. S. Patent No. 6,074, 776 discloses a method of controlling the flow of current through an increase in electrode resistance by making an insulating layer on the surface of the anode at high temperature, wherein the aromatic monomer additive introduced is used to cause a polymerization reaction in a high voltage state. It was. However, there is still a risk of ignition of the battery due to electrolyte decomposition when the temperature rises.

In Japanese Patent Laid-Open No. 2002-157979, it is excellent in thermal stability and a flame retardant magnesium alloy having a ignition temperature of 550 ° C. or higher is added to a nonaqueous electrolyte to prevent battery from igniting and burning even when the battery temperature rises. The method is disclosed. However, even in this case, even though the magnesium alloy can absorb some heat, it is not possible to absorb all the heat inflows due to the continuous temperature rise, so there is a risk of ignition.

In Japanese Patent Application Laid-Open No. 1993-150975, a method of pressurizing and charging an electrolyte with carbon dioxide is used to easily discharge the electrolyte along with carbon dioxide when the temperature of the battery rises abnormally. However, when the electrolyte is sucked into the inner pores of the separator or the electrode, the gas ignition alone is not easily released to the outside, so the risk of battery ignition due to decomposition of the electrolyte is still not solved.

Japanese Patent Laid-Open No. 1999-317232 proposes a method of flame retarding an electrolyte solution for a lithium secondary battery by adding a phosphate flame retardant such as trialkyl phosphate, trimethyl phosphate, or dimethyl phosphate to the electrolyte solution. However, in the case of halogen-based flame retardants that release inert gas to prevent contact with oxygen or phosphate-based flame retardants that melt by heat and coat the surface of the object to prevent contact with oxygen, a fire has already occurred and continues to propagate to the remaining electrolyte. In the state of being difficult to evolve. In addition, when a large amount of flame retardant is to be used to exert a safety improvement effect, the ion conductivity is lowered, which inevitably leads to deterioration of battery characteristics, thereby limiting the input amount of the material.

In view of the above problems, the present inventors have released a large amount of gas other than oxygen at a temperature T higher than the normal operating temperature range of the device, preferably higher than the normal temperature range of the device and lower than the shrinkage temperature of the separator. When the blowing agent is introduced into the exterior material of the electrochemical device as a constituent and / or coating component, the internal short circuit due to separation of the membrane and contact of the positive electrode caused by abnormally rising battery temperature due to external or internal factors It was conceived that the thermal runaway phenomenon, in which the temperature rises rapidly due to the occurrence and the resulting high current flow, is avoided.

Indeed, when the blowing agent is used as the coating component of the enclosure, at temperatures above the normal operating temperature of the cell, such as around 110 ° C., the coated blowing agent releases a large amount of inert gas to increase the internal pressure, leading to premature venting at the heat-sealed portion of the enclosure. By enabling it, the ignition can be prevented in advance. In addition, even if not vented, the released inert gas reduces the concentration of oxygen as a ignition element and prevents contact between oxygen and the electrolyte gas at the source, thereby suppressing the ignition and explosion of the battery by the flammable electrolyte gas. As a result, it was confirmed that the effect of improving the safety of the battery was excellent.

Accordingly, an object of the present invention is to provide an exterior material including a blowing agent capable of achieving the above-mentioned safety improvement effect, a manufacturing method thereof, and an electrochemical device having the exterior material.

The present invention relates to a case for an electrochemical device having at least one component layer, comprising a component, a coating component, or a component and a coating component constituting the component layer of the packaging material, higher than the normal operating temperature range of the device. Provided is an exterior packaging material for an electrochemical device, characterized in that it contains a blowing agent that releases a gas other than oxygen at a temperature (T).

The present invention also provides an electrochemical device using the packaging material described above.

In addition, the present invention comprises the steps of (a) adding a blowing agent and a binder polymer to a solvent or a dispersion medium to prepare a blowing agent-containing coating solution; And (b) coating the solution on at least part of the surface of at least one component layer constituting the packaging material and then drying the solution; It provides a method of manufacturing the exterior material described above.

The present invention can significantly improve the safety that has been pointed out as a problem of the conventional lithium secondary battery by using the blowing agent as a coating component and / or a component of the exterior material.

Hereinafter, the present invention will be described in detail, and a battery, particularly a lithium secondary battery, of the electrochemical device will be described as an example, but is not necessarily limited thereto.

The present invention uses a blowing agent as an ingredient and / or coating component of the exterior material for the electrochemical device, which is not applied to the conventional electrochemical device or is used as an auxiliary agent for forming the pore structure by thermal decomposition. Characterized in that.

Conventional blowing agents have been used for the purpose of reducing the amount of raw materials used in impact or by adding a rubber, polyurethane, EVA and the like to decompose at the processing temperature during extrusion or injection processing to release a large amount of gas to form bubbles. However, in the present invention, the blowing agent is used for the purpose of instantaneously decomposing in a narrow temperature range to eject a large amount of inert gas and to raise the pressure inside the battery.

When the foaming agent having the above characteristics is used as a constituent and / or coating component of the exterior material, it may exhibit an effect of improving the safety of the battery.

In other words, when the temperature of the battery rises abnormally due to internal or external factors such as high temperature storage or overcharging, the decomposition reaction of the electrolyte, the generation of flammable gas by the reaction between the electrolyte and the electrode, the internal short circuit caused by the shrinkage of the separator, etc. This causes the battery to ignite and explode. In order to solve such a problem, an electrolyte additive such as a monomer additive and a flame retardant to form an insulating layer was used, but the problem of deterioration of fundamental safety of the battery was not solved, and this resulted in deterioration of battery characteristics.

In contrast, in the present invention, by using a blowing agent that releases a large amount of a gas, such as an inert gas, except for oxygen (O ₂ ), which is one of the ignition elements, at a temperature higher than the normal operating temperature range of the battery, contact with oxygen, which is a ignition factor, is blocked. It is possible to fundamentally solve the occurrence of ignition of the battery.

In addition, the foaming agent coated on the surface of any one or more of the constituent layers of the packaging material, or contained as one or more constituents of the outer layer absorbs heat inside the battery and decomposes, thereby partially inhibiting the contraction of the membrane through temperature rise control. The internal short circuit caused by the contact between the electrode and the cathode can be suppressed.

In addition, the inert gas from which the blowing agent is decomposed has the effect of surrounding the flammable electrolyte gas to block the risk of ignition or explosion at a sufficiently high temperature in contact with oxygen.

In addition, in the present invention, since the blowing agent is added to the exterior material instead of the electrolyte solution additive, it does not affect the lithium ion conductivity dissolved in the electrolyte solution, thereby preventing performance degradation of the battery.

On the other hand, the present invention uses a foaming agent (및) as a component and / or coating component of the exterior material, and at the same time to detect the volume expansion of the foaming agent and the resulting pressure change in the device under abnormal conditions inside the device It is also possible to use safety means that can stop the operation of the device or change the abnormal conditions inside the device. In this case, the electrochemical device (a) the first safety means to stop the charging of the device or to change the state of charge to the discharge state by detecting the pressure change inside the device, or (b) to detect the pressure change inside the device Second safety means for dissipating heat or gas inside the device may be further provided, or both the first safety means and the second safety means may be further provided.

In the electrochemical device having the safety means as described above, the blowing agent is used for the purpose of instantaneously decomposing in a narrow temperature range to eject a large amount of inert gas and to increase the pressure inside the electrochemical device. The electrochemical device provided with such a blowing agent and safety means has a volume expansion caused by the gas blowing pressure generated from the blowing agent when the temperature of the battery is abnormally increased due to internal or external factors such as high temperature storage or overcharging. And prematurely actuating the first safety means to stop further operation of the device by increasing the internal pressure of the device and / or the second safety means to normally change abnormal conditions inside the device, thereby igniting the oxygen or flammable gas required for ignition. In addition, by accumulating internally stored heat to the outside, the safety of the battery can be improved by reducing the concentration of flammable gas and the temperature in the device.

Through such a complex action, it is possible to achieve an excellent safety improvement effect of the battery.

<Manufacture of exterior material>

A blowing agent capable of achieving the above-described action may be used as a constituent and / or coating component of an exterior material, and in this case, the blowing agent is instantaneously decomposed at a specific temperature range to generate a large amount of gas other than oxygen. Conventional blowing agents known in the art capable of releasing may be used without limitation. Alternatively, particles containing these components may be used.

The temperature (T) for decomposing the blowing agent to release a large amount of gas is not particularly limited as long as it is higher than the normal operating temperature of the battery, and is particularly higher than the normal operating temperature range of the battery, and shrinkage of the separator provided in the battery occurs. A temperature range lower than the temperature mentioned above is preferable. In one example, the temperature ranges from 90 to 150 ° C.

In addition, there is no particular limitation as long as the blowing agent is pyrolyzed and released as long as it is not a ignition element oxygen, but if possible inert gases such as N ₂ , He, Ne, Ar, Kr, Xe, CO ₂ , water vapor or their It is preferable that it is a mixed component.

Non-limiting examples of foaming agents that can be used include, but are not limited to, azo (-N = N-) based compounds or peroxide based compounds.

The azo (azo, -N = N-)-based compound is preferably an azobis 2-cyanobutane (azobis (2-cyanobutane) -based compound represented by Formula 1 below.

Since the azobis 2-cyanobutane series blowing agent rapidly releases a large amount of nitrogen, such as about 25 to 350 ml / g, in the range of 110 to 120 ° C., the safety improvement effect of the battery described above can be sufficiently satisfied.

Examples of the peroxide-based compound include, but are not limited to, 3-methyl benzoyl peroxide represented by the following Chemical Formula 2.

The peroxide-based blowing agent, for example, benzoyl peroxide as described above rapidly emits a large amount of carbon dioxide in the range of 140 ° C. at 100 degrees or less, thereby sufficiently satisfying the safety improvement effect of the battery described above. As long as it has a liquid or solid form and in addition to the foaming agent of the above components, it is possible to satisfy the above conditions and to improve the safety of the battery.

The blowing agent of the present invention may be included as a constituent of one or more constituent layers constituting the battery packaging material, or may be included by a method of forming a coating layer on part or all of the surface of the one or more constituent layers, and the constituents and coating components described above. May be included in both.

The battery packaging material may be a can type, a pouch type, or the like, and, in the case of the pouch type, may include a constituent layer such as a base layer, a lamination layer and a cast layer on the outside and inside of the packaging material.

Therefore, when the foaming agent of the present invention is included as a constituent of the packaging material layer, the foaming agent is included by mixing the foaming agent with the material forming the layer in the process of forming any one or more layers of the base layer, the inner lamination layer, and the cast layer. When the blowing agent is included as the coating layer of the packaging material layer, between the base layer and the inner lamination layer (see Fig. 2), between the inner lamination layer and the cast layer (see Fig. 3), the surface of the cast layer (see Fig. 4) The coating layer can be formed in the).

The blowing agent-containing coating layer may further include a binder polymer in addition to the blowing agent. In the present invention, the binder polymer is a concept including a binder polymer commonly used in the art, and may be applied in a liquid or paste form on a substrate to form a thin film after drying, and may be fixed by including a blowing agent in the thin film. The polymer is not particularly limited, and non-limiting examples thereof include polyurethane, polypropylene, nylon, polyvinylidene fluoride-co-hexafluoropropylene, and polyvinylidene fluoride. Polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene vinyl acetate Copolymer (polyethylene-co-vinyl acetate), polyethylene oxide (polyethylen e oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol Cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer Polyimide or mixtures thereof.

The component ratio of the blowing agent and the binder polymer is not particularly limited, but if possible, the blowing agent is preferably included in the range of 0.5 to 30 parts by weight based on 100 parts by weight of the binder polymer. If the foaming agent is used less than 0.5 parts by weight, the desired safety improvement effect may be insignificant, and when it exceeds 30 parts by weight, the coating layer on the surface of the exterior material may be easily peeled off, which may be a problem for desired performance.

According to the present invention, a method of manufacturing an exterior material including a foaming agent as a coating component of the exterior material is not particularly limited, but a preferred embodiment thereof includes (a) a foaming agent-containing coating solution by adding a blowing agent and a binder polymer to a solvent or a dispersion medium. Preparing a; And (b) coating the solution on at least part of the surface of at least one component layer constituting the packaging material and then drying the solution; It may include.

Hereinafter, an example of a method of coating the foaming agent on the exterior material will be described in detail.

First, 1) a binder polymer is added to a solvent or a dispersion medium (eg, NMP (N-methyl pyrroridone) to prepare a coating solution.

At this time, the binder polymer is appropriately added in 5 to 20 parts by weight (weight ratio) based on 100 parts by weight of the solvent or dispersion medium, but is not limited thereto.

In addition, the solvent or dispersant used to prepare the binder solution may be any of conventional solvents used in the art, and in particular, in order not to cause thermal decomposition of the blowing agent by solvent drying, Solvents with low boiling points are preferred. Non-limiting examples thereof include organic solvents such as N-methylpyrrolidone, acetone, dimethylacetamide, or dimethylformaldehyde, inorganic solvents such as water, or mixtures thereof. The amount of the solvent is sufficient to give sufficient adhesive strength in consideration of the thickness of the coating layer, the production yield. The solvents are removed by drying the coating solution on the surface of the packaging material.

2) After adding the blowing agent to the prepared coating solution, mixing and dispersing it completely, coating it on the exterior material and drying to complete the coating.

The blowing agent is appropriate to add 0.5 to 30 parts by weight relative to the binder polymer, but is not limited thereto. In addition, the coating method of the mixture of the blowing agent and the binder polymer on the exterior material may use a conventional coating method known in the art, for example, dip coating, die coating, roll coating, comma Various methods can be used, such as a (comma) coating or a mixing method thereof. In addition, the binder solution containing the blowing agent may be coated by impregnating part or all of the packaging material layer or nozzle spraying the solution. At this time, the exterior material may be coated in a range of 0.1 to 30 mg / cm ² by the blowing agent, but is not limited thereto. When the mixture of the blowing agent and the binder polymer is coated on the packaging material, the substrate is usually made of a metal such as aluminum, and thus the coating layer is preferably coated on the inner side of the packaging material. Since the coating layer may be formed on the substrate layer or on the inner lamination layer, after the coating layer is formed, another layer (inner lamination layer or cast layer) may be additionally formed to complete the manufacture of the packaging material.

<Production of Electrochemical Devices>

The present invention also provides an electrochemical device comprising a packaging material coated with a blowing agent or comprising the blowing agent as a component.

Electrochemical devices include all devices that undergo an electrochemical reaction, and specific examples thereof include all kinds of primary, secondary cells, fuel cells, solar cells, or capacitors. In particular, a lithium secondary battery is preferable among secondary batteries, and non-limiting examples thereof include a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.

The electrochemical device may be manufactured according to a conventional method known in the art, and for example, an electrolyte may be injected after assembling a separator between a positive electrode and a negative electrode, and the exterior material described in the present invention. It can be prepared by packaging.

The electrode to be applied to the electrochemical device of the present invention is not particularly limited, and according to a conventional method known in the art, the electrode active material may be prepared in a form bound to the electrode current collector.

The positive electrode active material may be a conventional positive electrode active material that can be used for the positive electrode of the conventional electrochemical device, non-limiting examples thereof, such as LiM _x O _y (M = Co, Ni, Mn, Co _a Ni _b Mn _c ) Lithium transition metal composite oxides (for example, lithium manganese composite oxides such as LiMn ₂ O ₄ , lithium nickel oxides such as LiNiO ₂ , lithium cobalt oxides such as LiCoO ₂ , and some of manganese, nickel, and cobalt oxides thereof Or a vanadium oxide containing lithium or the like, or a chalcogen compound (for example, manganese dioxide, titanium disulfide, molybdenum disulfide, or the like). Preferably LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , Li (Ni _a Co _b Mn _c ) O ₂ (0 <a <1, 0 <b <1, 0 <c <1, a + b _{+ c = 1), LiNi 1} -Y Co Y O 2, LiCo 1 - Y Mn Y O 2, LiNi 1 - Y Mn Y O 2 ( here, 0≤Y <1), Li ( Ni a Co b Mn _{c) O 4 (0 <a} <2, 0 <b <2, 0 <c <2, a + b + c = 2), LiMn 2 - z Ni z O 4, LiMn2 -z Co z O 4 ( here , 0 <Z <2), LiCoPO ₄ , LiFePO _4, or a mixture thereof. More preferably, it is a lithium transition metal composite oxide represented by the following formula (3).

Li _x MO ₂

Wherein M is Ni, Co, or Mn, and x is 0.05 ≦ x ≦ 1.10.

The negative electrode active material may be a conventional negative electrode active material that can be used for the negative electrode of the conventional electrochemical device, non-limiting examples of lithium metal or lithium alloy, carbon, petroleum coke, activated carbon, Lithium adsorbents such as graphite or other carbons. Non-limiting examples of anode current collectors include foils made of aluminum, nickel, or combinations thereof, and non-limiting examples of cathode current collectors include copper, gold, nickel, or copper alloys, or combinations thereof. By foil.

Conventional binders may be used, and non-limiting examples thereof include polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), teflon, or mixtures thereof.

The conductive agent is not particularly limited as long as it can improve conductivity, and non-limiting examples thereof include acetylene black or graphite.

Using the electrolyte salts is A ⁺ B ^- A salt of the structure, such as, A ⁺ is Li ^+, Na ^+, K ⁺ comprises an alkaline metal cation or an ion composed of a combination thereof, such as, and B ^- is PF ₆ ^-, BF _{^{4 -, Cl -, Br -}} , I -, ClO 4 -, AsF 6 -, CH 3 CO 2 -, CF 3 SO 3 -, N (CF 3 SO 2) 2 -, C (CF 2 SO 2) 3 ^- is a salt containing an anion ion or a combination thereof, such as. In particular, a lithium salt is preferable.

Organic solvents may be used conventional solvents known in the art, such as cyclic carbonates and / or linear carbonates, non-limiting examples of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl Carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethyl carbonate (EMC) Gamma butyrolactone (GBL), fluoroethylene carbonate (FEC), methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, pentyl acetate, methyl propionate, ethyl propionate, ethyl propionate, butyl propionate or Mixtures thereof and the like. Moreover, the halogen derivative of the said organic solvent can be used, and it can also be used for the battery using water.

The electrolyte injection may be performed at an appropriate step of the electrochemical device manufacturing process, depending on the manufacturing process and the required physical properties of the final product. That is, the device may be applied before the device assembly or at the final stage of device assembly.

In addition, the electrochemical device of the present invention (a) the first safety means for stopping the charging of the device or switching the state of charge to the discharge state by detecting the pressure change inside the device, or (b) the pressure change inside the device It may be further provided with a second safety means for dissipating heat or gas inside the device by sensing, or additionally provided with both the first safety means and the second safety means.

In the case of the electrochemical device of the present invention, particularly a lithium secondary battery, a porous separator is inserted between the positive electrode and the negative electrode by a conventional method known in the art, and then assembled into the exterior part by assembling the battery part according to a conventional assembly method. And it can be prepared by adding an electrolyte. In this case, when the packaging material is a can, the battery part may be wound and winded to form a jelly roll, and in the case of a pouch type, the battery part may be formed by winding or stacking the battery part. However, it is not limited thereto.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the following examples are for illustrating the present invention, and the scope of the present invention is not limited thereto.

Example 1

1-1. Manufacture of exterior material coated with foaming agent

5 parts by weight of Azobis (2-cyanobutane), a blowing agent, was added to 95 parts by weight of the coating solution, and then uniformly dispersed in a mixer for 1 hour. The prepared coating solution was coated on the inner side lamination layer 2 of the aluminum exterior material by a coating method at a weight of 10 mg / cm 2 and then dried by hot air at 110 to 120 ° C. (See Fig. 3)

1-2. Battery manufacturing

(Cathode production)

Carbon powder as a negative electrode active material, polyvinylidene fluoride (PVDF) as a binder, and a conductive agent were mixed in a weight ratio of 91: 4: 5, and then dispersed in NMP to prepare a negative electrode mixture slurry. This negative electrode mixture slurry was uniformly applied to a cross section of a Cu foil having a thickness of 10 μm with a negative electrode current collector with a comma gap of 200 μm and then dried. The coating speed at this time was 3 m / min. Stability was measured by sampling the dried electrode, the results of which are shown in Table 1 below.

(Anode manufacturing)

A positive electrode mixture slurry was prepared by mixing a lithium cobalt composite oxide as a cathode active material, carbon as a conductive agent, and PVDF as a binder in a weight ratio of 95: 2.5: 2.5, and then adding it to NMP as a solvent. The positive electrode mixture slurry was applied to an Al thin film of a positive electrode current collector having a thickness of 20 μm, and coated and dried in the same manner as the negative electrode.

 (Battery manufacturing)

Stacked negative electrode and positive electrode were laminated in order to produce a polymer cell, which was properly embedded in the exterior material (34 mm × 43 mm × 36 mm thick) manufactured in Example 1-1, and then from the current collector. The negative electrode lead made of nickel was collected by welding the positive electrode lead made of aluminum, and then welded with the outer tab to remove the lead wire out of the cell. An electrolyte was injected into the prepared battery, and LiPF ₆ was used as a solvent and an electrolyte in which EC and EMC were mixed in a volume ratio of 1: 2.

The battery prepared as described above was charged to 4.2V with a constant current. The standard capacity of the electrolyte secondary battery was 950 mAh, and the efficiency was measured at a rate of 1 C (950 mA / h) and 0.2 C (190 mA / h) at a constant current from 4.2 V to 3 V, followed by a safety test of the battery. .

[Example 2]

Instead of using 5 parts by weight of the blowing agent in the coating liquid in the manufacture of the exterior material, except for changing the coating liquid to 85 parts by weight and 15 parts by weight of the foaming agent, respectively, by performing the same method as in Example 1 the exterior material and a lithium secondary battery having the same Was prepared.

Example 3

When manufacturing the exterior material was coated in the same manner as in Example 1, except that the coating surface is the inner cast layer, the same method as in Example 1 was carried out to prepare a packaging material and a lithium secondary battery having the same. (See Fig. 4)

Example 4

When manufacturing the exterior material was coated in the same manner as in Example 2, except that the coating surface is the inner cast layer, the same method as in Example 2 was prepared to prepare a packaging material and a lithium secondary battery having the same.

Comparative Example 1

A battery was manufactured in the same manner as in Example 1, except that a conventional aluminum packaging material without a blowing agent was used. (See Fig. 1)

Experimental Example 1 Evaluation of Safety of Battery

In order to evaluate the safety of the lithium secondary battery having a packaging material coated with a blowing agent according to the present invention, it was performed as follows.

The lithium secondary batteries prepared in Examples 1 to 4 were used, and the lithium secondary batteries of Comparative Example 1 prepared in accordance with conventional methods known in the art were used without using a blowing agent as a control.

1-1. Hot box  Experiment

Each cell was stored for 1 hour at a high temperature of 150 ° C., respectively, after which the state of the cell is shown in Table 1 below.

As a result of the experiment, the lithium secondary battery of Comparative Example 1 having an exterior material manufactured according to a conventional method without using a foaming agent did not generate vents or ignited or exploded even when the temperature was raised to 150 ° C, while containing a foaming agent. In the battery of Examples 1 to 4, when the temperature passes 120 ° C., the blowing agent contained in the exterior material discharges nitrogen gas, and nitrogen is discharged together with the internal electrolyte gas at 135 ° C. while the tab and the heat-sealed seal are opened. And the temperature was reduced, indicating that the effect of improving safety was excellent (see Table 1).

1-2. Crush  Experiment

Crush test was performed using each cell, and then the state of the cell is described in Table 1 below.

The internal short circuit caused by the crush caused the temperature to rise, but the cells of Examples 1 to 4 were released by nitrogen gas at around 120 ° C., and the vents were opened. It was confirmed again that the effect of improving the safety (see Table 1).

Test Items Condition Example 1 Example 2 Example 3 Example 4 Comparative example hot box 150 ℃, 1 hour 4/10 3/10 2/10 1/10 10/10 crush test 13 kN 2/10 2/10 1/10 1/10 6/10

1 is a cross-sectional structure of a general pouch type packaging material used in a lithium polymer battery, used in Comparative Example 1. FIG.

2 is a cross-sectional structure of a packaging material in which a foaming-agent-containing coating layer is formed between an aluminum substrate and an inner lamination layer.

3 is a cross-sectional structure of a packaging material in which a foaming-agent-containing coating layer is formed between the inner lamination layer and the cast layer described in Example 1. FIG.

4 is a cross-sectional structure of a packaging material having a foaming agent-containing coating layer formed on the cast layer surface described in Example 3. FIG.

&Lt; Brief Description of Drawings &

1: aluminum base

2: inner lamination layer

3: cast layer

4: outer lamination layer

5: foaming agent coating layer

Claims (21)

A pouch type case for an electrochemical device comprising at least one component layer selected from the group consisting of a base layer, a lamination layer, and a cast layer, the base layer and lamination of the case Between the layers, between the lamination layer and the cast layer, on the surface of the cast layer, a blowing agent which releases gas other than oxygen at a temperature T above the normal operating temperature range of the device is coated in the range of 0.1 to 30 mg / cm ² . A pouch type exterior material for an electrochemical device characterized by the above-mentioned. The pouch-type exterior material for an electrochemical device according to claim 1, wherein the temperature (T) is higher than a normal operating temperature of the device and lower than a temperature at which shrinkage of the separator provided in the device occurs. The pouch-type exterior material for an electrochemical device according to claim 1, wherein the temperature (T) is in a range of 90 to 150 ° C. The pouch-type exterior material for an electrochemical device according to claim 1, wherein the gas is at least one inert gas selected from the group consisting of N ₂ , He, Ne, Ar, Kr, Xe, CO ₂ , and water vapor. The pouch type packaging material according to claim 1, wherein the blowing agent is an azo (-N = N-)-based compound or a peroxide-based compound. The pouch-type exterior material for an electrochemical device according to claim 5, wherein the azo compound is a compound represented by the following Chemical Formula 1. [Formula 1]

The pouch-type exterior material for an electrochemical device according to claim 5, wherein the peroxide-based compound is a compound represented by the following Chemical Formula 2. [Formula 2]

A pouch type for an electrochemical device according to claim 1, wherein a coating layer containing the blowing agent is formed on a part or all of the surfaces of one or more constituent layers constituting the packaging material, and the coating layer comprises a binder polymer. Exterior materials. The pouch-type exterior material for an electrochemical device according to claim 8, wherein the content of the blowing agent is 0.5 to 30 parts by weight based on 100 parts by weight of the binder polymer. delete The method of claim 1, wherein the blowing agent is characterized in that by releasing a gas other than oxygen into the battery at a temperature (T) above the normal operating temperature range of the battery, it can block the contact with oxygen to prevent ignition Pouch type exterior material for devices. The pouch type according to claim 1, wherein the blowing agent absorbs and decomposes heat inside the device at a temperature (T) equal to or higher than the normal operating temperature range of the device, thereby suppressing an increase in the temperature inside the device. Exterior materials. The pouch-type exterior material for an electrochemical device according to claim 1, wherein the electrochemical device is a lithium secondary battery. delete delete An electrochemical device using the packaging material according to any one of claims 1 to 9 and 11 to 13. 17. The device of claim 16, wherein the electrochemical device comprises: (a) first safety means for stopping charging of the device or switching the charging state to a discharge state by detecting a pressure change inside the device, and (b) a pressure inside the device. And a second safety means for dissipating heat or gas inside the device through change detection, or both the first safety means and the second safety means. 18. The method of claim 17, wherein the blowing agent operates by detecting a change in pressure inside the device by releasing a gas other than oxygen into the device at a temperature T above the normal operating temperature range of the device to increase the pressure inside the device. An electrochemical device, characterized in that the first safety means, the second safety means, or both the first and second safety means can be operated. The electrochemical device of claim 16, wherein the electrochemical device is a lithium secondary battery. As a manufacturing method of the pouch type exterior material for electrochemical elements as described in any one of Claims 1-9, (a) adding a blowing agent and a binder polymer to a solvent or a dispersion medium to prepare a blowing agent-containing coating solution; And (b) coating the solution on at least part of the surface of at least one component layer selected from the group consisting of a base layer, a lamination layer, and a cast layer constituting the pouch-type exterior material for an electrochemical device, and then drying the solution; Method of manufacturing a pouch-type exterior material for an electrochemical device comprising a. 21. The method of claim 20, wherein step (b) impregnates some or all of the foam constituent layer in the foaming agent-containing coating solution, or nozzles are applied to some or all of the surfaces of the one or more constituent layers constituting the packaging. A method of manufacturing a pouch type exterior material for an electrochemical device, characterized by coating by a spraying method.

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