KR20180013345A - Lithium secondary battery having improved stability - Google Patents

Abstract

The present invention relates to a lithium secondary battery having improved stability. The lithium secondary battery comprises a phase change material (PCM) in a gasket, thereby absorbing heat of the PCM when heat at high temperature occurs in the lithium secondary battery, lowering the temperature of the gasket and preventing thermal deformation. Accordingly, side reaction and explosion of cells caused by thermal deformation of the gasket can be prevented and thermal stability can be improved.

Description

[0001] Lithium secondary battery having improved stability [0002]

The present invention relates to a lithium secondary battery having improved stability.

2. Description of the Related Art As technology development and demand for mobile devices such as portable computers, portable telephones, cameras, and the like are increasing, demand for secondary batteries as energy sources is rapidly increasing. A large amount of research has been conducted on lithium secondary batteries, which exhibit high energy density and operating potential among these secondary batteries, have a long cycle life and low self discharge rate, and have been widely used and commercialized.

However, when the lithium secondary battery is overcharged due to a failure such as a misuse and a charger, or when an internal short circuit occurs due to design defects, penetration, external impact, or the like of the battery itself, the battery temperature may rapidly rise. When the temperature of the battery rises rapidly, the battery becomes very unstable due to the reaction of the electrolyte with lithium or the oxidation of the anode. The solvent of the electrolyte is decomposed to generate gas, and the decomposition gas of the solvent is ignited, Which can lead to an explosion of.

When the lithium secondary battery rises to a high temperature of 100 ° C or higher, the current interruption device (Current Interrupt Device, CID), which is a safety device inside the battery, prevents the current from flowing to prevent the reaction.

However, when the gasket existing between the battery case and the cap assembly is melted, the positive electrode and the negative electrode are connected to each other to cause a re-reaction There is a problem that a cell explosion may occur despite the CID.

The present invention provides a lithium secondary battery having improved thermal stability at high temperatures, a battery module including the same, and a battery pack.

The present invention relates to an electrode assembly having an anode, a cathode, and a separator interposed between the anode and the cathode; A battery case having the electrode assembly therein and having an upper opening; A cap assembly capable of sealing an upper opening of the battery case; And a gasket interposed between the battery case and the cap assembly, wherein the gasket includes a phase change material (PCM) therein.

The present invention also provides a battery module and a battery pack including the lithium secondary battery.

According to the present invention, the phase change material (PCM) is contained in the gasket sealing the battery case and the cap assembly, so that when the high temperature heat is generated inside the lithium secondary battery, the phase change material (PCM) Temperature can be lowered, and thermal deformation can be prevented. Accordingly, it is possible to provide a lithium secondary battery which can prevent a side reaction and an explosion of a cell due to thermal deformation of a gasket and improve thermal stability.

1 is a sectional view of a lithium secondary battery according to an embodiment of the present invention.
FIG. 2 is a schematic view showing an enlarged view of the first embodiment of the portion "A" in FIG.
3 is an enlarged schematic view of the second embodiment of the portion 'A' in FIG.

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

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are for the purpose of clarifying the present invention and are not to be construed as limiting the present invention. The shape and size of the elements in the drawings may be exaggerated for clarity, and parts that are not related to the description are omitted, and the same reference numerals are used for the same components in the same reference numerals.

1 is a sectional view of a lithium secondary battery according to an embodiment of the present invention.

Referring to FIG. 1, a lithium secondary battery 100 according to an embodiment of the present invention includes an electrode assembly 200, a battery case 300 having an electrode assembly 200 and an upper opening formed therein, A cap assembly 400 capable of sealing an upper opening of the cap 300 and a gasket 350 interposed between the battery case 300 and the cap assembly 400. Inside the gasket 350, Phase change material (PCM).

The electrode assembly 200 includes an anode 210, a cathode 220, and a separator 230 interposed between the anode 210 and the cathode 220. The electrode assembly 200 includes a separator 230 having a sheet- A jelly-roll type in which a separator 230 is interposed between the cathode 210 and the cathode 220. The jelly-roll type electrode assembly is easy to manufacture, has a high energy density per weight, and is easy to store in a battery case, but is not necessarily limited to a jelly-roll type.

The battery case 300 accommodates the electrode assembly 200 together with the electrolytic solution and a cap assembly 400 is formed at an upper opening of the battery case 300 to seal the battery case 300.

The cap assembly 400 includes safety devices such as a safety vent 500 for discharging high-pressure gas and a current interrupt device (CID) for blocking current, a top-cap And the cap assembly 400 may be hermetically coupled to the battery case 300 by a gasket 350.

The lithium secondary battery generates heat inside the battery due to overcharging due to misuse and failure of the charger, defective design of the battery itself, penetration, external impact, or internal short circuit due to repeated expansion and contraction of the electrode assembly A phenomenon may occur. The conventional lithium secondary battery has a problem that internal components of the battery are melted due to such a heat generation phenomenon.

When the lithium secondary battery rises to a high temperature of 100 캜 or more due to a heat generation phenomenon, the conductive pattern of the current interruption element is cut off to cut off the current.

However, when the current interruption device operates, the gasket still melts at a high temperature. When the gasket is melted, a cap assembly connected to the anode and a battery case connected to the cathode contact each other, There is a problem that explosion of the lithium secondary battery may occur.

Accordingly, in the present invention, by including the phase change material (PCM) in the gasket 350 of the lithium secondary battery, when the high temperature heat is generated inside the lithium secondary battery, the phase change material (PCM) And to prevent thermal deformation of the gaskets and internal components.

Accordingly, it is possible to provide a lithium secondary battery which can prevent side reactions and cell explosion due to thermal deformation of gaskets and internal parts of the battery, and improved thermal stability.

The phase change material (PCM) refers to a substance used for the purpose of storing energy or maintaining a constant temperature by utilizing absorption or release effect of latent heat contained in the material. Here, latent heat means heat that absorbs or releases the same when the material is phase-changed, that is, from solid to liquid or from liquid to solid, from liquid to gas or from gas to liquid, Is much greater than the amount of sensible heat (heat absorbed or released in the absence of phase change).

Specifically, the phase change material (PCM) may emit heat or change the phase of the phase change material in a corresponding temperature range, or absorb heat to increase or decrease the ambient temperature. For example, if a phase change material (PCM) at a temperature of 100 ° C is used, an endothermic reaction with a phase change material (PCM) takes place when the internal temperature of the lithium secondary battery reaches 100 ° C, thereby lowering the temperature inside the lithium secondary battery .

The phase change material (PCM) according to the present invention may be any one or a mixture of two or more selected from the group consisting of inorganic substances in the form of hydrates, paraffinic hydrocarbons and organic acids.

The inorganic substance in the hydrate form is NaNH ₄ SO ₄ .2H ₂ O, Na ₂ SO ₄ .10H ₂ O, Na ₂ SiO ₃ .5H ₂ O, Na ₃ PO ₄ .12H ₂ O, Na (CH ₃ COO) ₂ O, NaHPO ₄ .12H ₂ O, K ₂ HPO ₄ .3H ₂ O, Fe (NO ₃ ) ₃ .9H ₂ O, FeCl ₃ .2H ₂ O, Fe ₂ O ₃ .4SO ₄ .9H ₂ O, Ca It may be a _{(NO 3) 2 · 3H 2} O, CaCl 2 · 6H 2 O, K 2 HPO 4 · 3H 2 O and K ₃ PO ₄ · 7H ₂ O which one or two or more kinds of mixtures selected from the group consisting of.

The paraffinic hydrocarbon may be n-octanoic acid, n-heptanoic acid, n-pentanoic acid, n-tetracholic acid, Heptadecane, n-hexadecane, n-pentadecane, n-tetradecane, and n-tridecane, or mixtures of two or more thereof.

The organic acid may be any one or a mixture of two or more selected from the group consisting of n-octanoic acid, tartaric acid, oxalic acid, acetic acid, lactic acid and chloroacetic acid.

The phase change material (PCM) according to an embodiment of the present invention may have a phase transition temperature of 45 ° C to 150 ° C. The phase change material (PCM) may exhibit an endothermic reaction that absorbs heat due to a phase change from solid to liquid at a temperature of 45 ° C to 150 ° C. More preferably, the phase change material (PCM) may have a phase transition temperature between 60 ° C and 150 ° C, and most preferably between 80 ° C and 150 ° C.

Accordingly, it is possible to prevent the internal temperature of the lithium secondary battery from exceeding 150 캜 even when the lithium secondary battery generates heat, and it is possible to prevent the gasket from being thermally deformed at a temperature exceeding 150 캜, The stability can be improved.

The gasket 350 may include the phase change material (PCM), wherein the phase change material (PCM) may be formed of a phase change material (PCM) PCM) may be dispersed in the gasket, or may include a phase change material (PCM) layer in the gasket, but the present invention is not limited thereto.

Hereinafter, the mode of inclusion of a phase change material (PCM) in a gasket according to a preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic view showing an enlarged view of the first embodiment of the portion "A" in FIG.

Referring to FIG. 2, the gasket 350 according to the first embodiment of the present invention includes a polymer resin 10, and the phase change material 11 may be dispersed in the polymer resin 10.

The polymer resin 10 may be a heat-resistant polymer generally used as a material of a gasket. Examples of the polymer include a polyester, a polybutylene, a polyethylene, a polypropylene, a polystyrene, a nylon, a polycaprolactone, a polyethylene terephthalate, Polyurethane, polyurethane, gelatin, chitosan, cellulose, polymethyl methacrylate, and derivatives thereof, and is not particularly limited thereto.

The polymer resin 10 can ensure insulation and sealability between the cap assembly 400 and the battery case 300 in the lithium secondary battery.

The phase change material 11 dispersed in the polymer resin 10 may be in a particulate form and a coating layer 12 including a heat resistant polymer may be further formed on the surface of the phase change material 11. [

The coating layer 12 serves to prevent the problem caused by the flowability of the phase-change material phase-transformed to the liquid when the phase-change material 11 is phase-transformed from solid to liquid. For example, when a phase change material (PCM) having a phase transition temperature of 100 ° C is used, an endothermic reaction with a phase change material (PCM) occurs while the internal temperature of the lithium secondary battery reaches 100 ° C, The material can be transformed from solid to liquid and flowable. At this time, the coating layer 12 including the heat-resistant polymer having a thermal deformation temperature higher than 100 ° C is not thermally deformed due to the endothermic reaction of the phase change material (PCM) Can be prevented.

The heat-resistant polymer included in the coating layer 12 is not particularly limited as long as it does not interfere with heat transfer with the outside of the phase-change material 11 and can prevent the flowability of the phase-change material. For example, At least one selected from the group consisting of polyester, polybutylene, polyethylene, polypropylene, polystyrene, nylon, polycaprolactone, polyethylene terephthalate, polyurethane, gelatin, chitosan, cellulose, polymethyl methacrylate and derivatives thereof And may be the same material as the polymer resin 10 forming the gasket, or may be a different material. Preferably, the heat-resistant polymer has a heat distortion temperature higher than the phase transition temperature of the phase change material (11).

The thickness of the coating layer 12 may vary from 1 nm to 1 mm depending on the size of the phase change material 11. The phase change material 11 in the coating layer 12 may be heat transferred to the outside of the coating layer 12 The thickness is not particularly limited as long as it does not hinder smooth operation.

3 is an enlarged schematic view of the second embodiment of the portion 'A' in FIG.

3, a gasket 350 according to a second embodiment of the present invention includes a phase change material layer 21 comprising a phase change material (PCM) and an outer surface of the phase change material layer 21 , And a protective layer 22 including a heat-resistant polymer.

The phase change material layer 21 may be entirely made of a phase change material (PCM), or may be a form in which a particle phase phase change material (PCM) is dispersed in a polymer resin like the gasket of the first embodiment have.

The protective layer 22 serves to prevent the problem due to the flowability of the phase change material phase-changed to liquid when the phase change material (PCM) of the phase change material layer 21 is phase-changed from solid to liquid. In order to prevent the flow of the phase-changed phase-change material, the protective layer 22 preferably covers the outer surface of the phase-change material layer 21.

The heat resistant polymer included in the protective layer 22 is not particularly limited as long as it does not interfere with heat transfer to the outside of the phase change material layer 21 and can prevent the flowability of the phase change material. For example, any of those selected from the group consisting of polyester, polybutylene, polyethylene, polypropylene, polystyrene, nylon, polycaprolactone, polyethylene terephthalate, polyurethane, gelatin, chitosan, cellulose, polymethyl methacrylate, And may include one or more. Preferably, the heat-resistant polymer has a heat distortion temperature higher than the phase transition temperature of the phase change material (11).

By forming the protective layer 22, not only the flowability of the phase change material can be prevented, but also the insulating property and the sealing property between the cap assembly 400 and the battery case 300 in the lithium secondary battery can be secured.

The thickness of the passivation layer 22 may be between 10% and 20% of the thickness of the phase change material layer 21 and may vary in the above range depending on the thickness of the phase change material layer 21, The thickness of the phase change material PCM of the material layer 21 is not particularly limited as long as the thickness of the phase change material PCM does not hinder the heat transfer to the outside of the protective layer 12 smoothly.

The phase change material (PCM) according to an embodiment of the present invention may be contained in an amount of 10 to 50% by weight based on the total weight of the gasket.

If the phase change material (PCM) is contained in an amount of less than 10% by weight based on the total weight of the gasket, the heat generated in the secondary battery can not be sufficiently absorbed and the thermal deformation of the gasket can not be prevented. There is a problem that a short circuit occurs between the anode and the cathode. In addition, when the phase change material (PCM) is contained in an amount of more than 50% by weight based on the total weight of the gasket, the effect of improving the thermal stability is insufficient, the flowability of the phase change material (PCM) The insulating property and the sealing property of the gasket may be deteriorated.

On the other hand, the electrode to be applied to the lithium secondary battery of the present invention is not particularly limited and can be produced by a conventional method known in the art.

The anode 210 of the electrode assembly 200 may be manufactured by applying a slurry prepared by mixing a cathode mixture containing a cathode active material, a conductive material and a binder to an organic solvent, applying the slurry on the cathode collector, followed by drying and rolling, The cathode 220 can be prepared by applying a slurry prepared by mixing a negative electrode mixture containing a negative electrode active material, a conductive material and a binder to an organic solvent, applying the slurry on the negative electrode collector, followed by drying and rolling.

The cathode active material is not particularly limited, but a lithium transition metal oxide can be specifically used. Examples of the lithium transition metal oxide include lithium cobalt oxide such as LiCoO ₂ , lithium nickel cobalt manganese composite oxide such as LiNi _x Co _y Mn _z O ₂ , lithium nickel oxide such as LiNiO ₂ , LiMn ₂ O _4, and the like. These may be used singly or in combination.

The anode active material may be a carbonaceous material, lithium metal, silicon, or tin, from which lithium ions can be occluded and released. Preferably, carbon materials can be used, and carbon materials such as low-crystallinity carbon and high-crystallinity carbon can be used. Examples of the low crystalline carbon include soft carbon and hard carbon. Examples of highly crystalline carbon include natural graphite, Kish graphite, pyrolytic carbon, liquid crystal pitch carbon fiber high temperature sintered carbon such as mesophase pitch based carbon fiber, mesocarbon microbeads, mesophase pitches and petroleum or coal tar pitch derived cokes are representative.

The current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery. For example, the current collector may be formed of a conductive material such as carbon, stainless steel, aluminum, nickel, titanium, , Nickel, titanium, silver, or the like may be used.

Examples of the binder include polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, Polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM) Various kinds of binder polymers such as sulfonated EPDM, styrene butadiene rubber (SBR), fluorine rubber, poly acrylic acid and polymers substituted with Li, Na or Ca, or various copolymers thereof are used .

The conductive material is not particularly limited as long as it can be generally used in the art. For example, artificial graphite, natural graphite, carbon black, acetylene black, ketjen black, denka black, thermal black, channel black, A metal selected from the group consisting of aluminum, tin, bismuth, silicon, antimony, nickel, copper, titanium, vanadium, chromium, manganese, iron, cobalt, zinc, molybdenum, tungsten, silver, gold, lanthanum, ruthenium, , Polythiophene, polyacetylene, polypyrrole, or a combination thereof. In general, a carbon black-based conductive material may be used.

As the separator 230 in the electrode assembly 200, any porous substrate commonly used may be used. For example, a polyolefin porous membrane or a nonwoven fabric may be used, but the present invention is not limited thereto.

 Examples of the polyolefin-based porous film include polyolefin-based polymers such as polyethylene, polypropylene, polybutylene, and polypentene, such as high-density polyethylene, linear low density polyethylene, low density polyethylene and ultra high molecular weight polyethylene, One membrane can be mentioned. The nonwoven fabric may include, in addition to the polyolefin nonwoven fabric, for example, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate ), Polyimide, polyetheretherketone, polyethersulfone, polyphenylene oxide, polyphenylenesulfide, and polyethylene naphthalene, which may be used alone or in combination, And nonwoven fabrics formed by mixing these polymers. The structure of the nonwoven fabric may be a spun bond nonwoven fabric or a meltblown nonwoven fabric composed of long fibers.

The electrolyte of the lithium secondary battery according to the present invention may include a non-aqueous organic solvent and a metal salt.

Examples of the non-aqueous organic solvent include propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile , Organic solvents composed of dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethyl carbonate (EMC), gamma-butyrolactone or mixtures thereof .

LiBCl ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ , LiBF ₄ , LiBF ₄ , LiBF ₄ , LiBF ₄ , _{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, imide and the like can be used.

The lithium secondary battery according to the present invention may be a cylindrical, square, or pouch type secondary battery, but is not limited thereto as long as it is a charge / discharge device.

The present invention also provides a battery module including the lithium secondary battery as a unit cell and a battery pack including the same. The battery module and the battery pack may be used as a power source for a device such as a mobile electronic device including the lithium secondary battery having a stable stable line at a high temperature.

The battery pack includes a power tool; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle (PHEV); Or a system for power storage. ≪ RTI ID = 0.0 > [0027] < / RTI >

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Example  1: PCM - hydrate form minerals

The top cap of the cap assembly and the cylindrical battery case were fabricated using SPCE (cold rolled steel plate) plated with Ni. An opening is formed in the upper end of the battery case, and an electrode assembly is mounted inside the opening through the opening of the cylindrical battery case.

Then, a gasket was inserted into the upper end of the battery case. The gasket was prepared by dispersing Na ₂ SiO ₃ .5H ₂ O (phase transition temperature: 72 ° C), which is a phase change material (PCM), on the surface of the Na ₂ SiO ₃ .5H ₂ O particles, To form a polyester coating layer. At this time, the phase change material (PCM) Na ₂ SiO ₃ .5H ₂ O was included in an amount of 10 wt% based on the total weight of the gasket.

Then, the current interrupting element and the safety vent are connected to the inside of the gasket, the PTC element and the top cap are mounted, the upper end of the battery case is bent inward, and then the clamping and pressurizing process is performed, 10 mm in diameter, 18 mm in length, and 65 mm in length).

Example  2: PCM-paraffinic hydrocarbon

A lithium secondary battery was prepared in the same manner as in Example 1 except that the phase change material (PCM) was changed to Paraffin 34-Carbons (phase transition temperature: 75.9 ° C).

Example  3: PCM - Organic acid

A lithium secondary battery was prepared in the same manner as in Example 1, except that the phase change material (PCM) was changed to (CHCO ₂ NH ₃ ) ₂ (phase transition temperature: 102 ° C).

Example  4: PCM layer / protective layer formation gasket

A phase change material layer containing phase change material (PCM) Na ₂ SiO ₃ .5H ₂ O (phase transition temperature: 72 ° C) was formed to a thickness of 1 μm as a gasket in Example 1, A lithium secondary battery was prepared in the same manner as in Example 1, except that a protective layer containing polyester was formed to a thickness of 0.2 mu m on the surface.

Comparative Example

A lithium secondary battery was produced in the same manner as in Example 1, except that a gasket made of polyester was used as the gasket in Example 1.

< Experimental Example > Evaluation of thermal stability

The lithium secondary batteries prepared in Examples and Comparative Examples were stored in a high-temperature storage chamber at 150 ° C for 1 hour, and their thermal stability was evaluated.

Example 1 Example 2 Example 3 Example 4 Comparative Example Gasket thermal deformation X X X X O Shot Occurrence X X X X O

As can be seen from the results of Table 1, in the comparative example in which the phase change material (PCM) is not contained in the gasket, the gasket is deformed at a high temperature, It can be confirmed that the gaskets were not thermally deformed and no short circuit occurred.

While the present invention has been particularly shown and described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, And falls within the scope of the present invention.

Claims (14)

An electrode assembly having an anode, a cathode, and a separator interposed between the anode and the cathode;
A battery case having the electrode assembly therein and having an upper opening;
A cap assembly capable of sealing an upper opening of the battery case; And
And a gasket interposed between the battery case and the cap assembly,
Wherein the gasket comprises a phase change material (PCM) therein.
The method according to claim 1,
Wherein the phase change material is any one or a mixture of two or more selected from the group consisting of an inorganic material in the form of a hydrate, a paraffinic hydrocarbon and an organic acid.
3. The method of claim 2,
The inorganic substance in the hydrate form is NaNH ₄ SO ₄ .2H ₂ O, Na ₂ SO ₄ .10H ₂ O, Na ₂ SiO ₃ .5H ₂ O, Na ₃ PO ₄ .12H ₂ O, Na (CH ₃ COO) ₂ O, NaHPO ₄ .12H ₂ O, K ₂ HPO ₄ .3H ₂ O, Fe (NO ₃ ) ₃ .9H ₂ O, FeCl ₃ .2H ₂ O, Fe ₂ O ₃ .4SO ₄ .9H ₂ O, Ca _{(NO 3) 2 · 3H 2} O, CaCl 2 · 6H 2 O, K 2 HPO 4 · 3H 2 O and K ₃ PO ₄ · 7H any one or two of the lithium secondary battery or more mixtures selected from the group consisting of ₂ O .
3. The method of claim 2,
The paraffinic hydrocarbon may be n-octanoic acid, n-heptanoic acid, n-pentanoic acid, n-tetracholic acid, N-heptadecane, n-hexadecane, n-pentadecane, n-tetradecane, and n-tridecane, or a mixture of two or more selected from the group consisting of n-heptadecane, decane, n-octadecane, n-heptadecane,
3. The method of claim 2,
Wherein the organic acid is any one or a mixture of two or more selected from the group consisting of n-octanoic acid, tartaric acid, oxalic acid, acetic acid, lactic acid and chloroacetic acid.
The method according to claim 1,
The gasket includes a polymer resin,
Wherein the phase change material is dispersed in the polymer resin.
The method according to claim 6,
Wherein the phase change material is in the form of a particle, and a coating layer including a heat resistant polymer is further formed on a surface of the phase change material.
The method according to claim 1,
The gasket
A phase change material layer comprising the phase change material; And
And a protective layer surrounding the outer surface of the phase change material layer and including a heat resistant polymer.
8. A method according to any one of claims 7 and 8,
The heat-resistant polymer is preferably a polyester, a polybutylene, a (polyethylene, a polypropylene, a polystyrene, a nylon, a polycaprolactone, a polyethylene terephthalate, a polyurethane, a gelatin, a chitosan, a cellulose, a polymethyl methacrylate, A lithium secondary battery comprising:
The method according to claim 1,
Wherein the phase change material has a phase transition temperature of 45 캜 to 150 캜.
The method according to claim 1,
Wherein the phase change material is contained in an amount of 10% by weight to 50% by weight based on the total weight of the gasket.
A battery module comprising the lithium secondary battery of claim 1 as a unit cell.
13. A battery pack comprising the battery module of claim 12 and used as a power source of the device.
14. The method of claim 13,
Wherein the device is a mobile electronic device.

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