TW201448318A - High voltage lithium secondary battery - Google Patents

Abstract

Provided are a lithium secondary battery including a cathode, an anode, a separator, and a gel polymer electrolyte, wherein the gel polymer electrolyte includes an acrylate-based polymer and a charge voltage of the battery is in a range of 4.3 V to 5.0 V, and a method of preparing the lithium secondary battery. A high-voltage lithium secondary battery of the present invention has excellent capacity characteristics at a high voltage of 4.3 V or more.

Description

High voltage lithium secondary battery

The present invention relates to a high voltage lithium secondary battery, and more particularly to a gel polymer electrolyte comprising a monomer comprising 2 to 6 acrylate groups and having a charging voltage in the range of 4.3 volts to 5.0 volts. High voltage lithium secondary battery.

Recently, the trend of portability, miniaturization, light weight and high performance in the electronic device, electronic products, information and communication industries has grown rapidly. Accordingly, high-performance lithium secondary batteries are used as an energy source for these portable electronic devices, and their demand is rapidly increasing. Secondary batteries, which can be reused by charging and discharging, are essential for the energy of portable electronic devices for information and communication, electric bicycles or electric vehicles.

In particular, since the performance of these products depends on batteries as a key component, consumer demand for high capacitance batteries is increasing. The development of high-voltage battery systems has become a trend based on the increase in battery capacitance.

Regarding a typical lithium secondary battery, charging is performed at a charging voltage of 3.0 volts to 4.2 volts. Therefore, by using more than above The voltage charging voltage (4.3 volts to 5.0 volts) is used to obtain a higher electrical capacitance.

However, in the case where a carbonate-based nonaqueous solvent is used as an electrolyte solution together with a typical anode and cathode, the oxidizing power is increased by charging at a voltage higher than a typical charging voltage (4.2 volts), the anode and the cathode. It will be damaged and the decomposition reaction of the electrolyte solution will occur in the charge and discharge cycles. Therefore, the life characteristics will decrease rapidly.

Regarding the use of LiCoO ₂ as a typical cathode active material, since the thermal and electrochemical properties are not appropriate when used at a high voltage, the above limitations must be improved.

The present invention proposes a high voltage lithium secondary battery which has excellent life characteristics and capacitance characteristics at a high voltage of 4.3 volts to 5.0 volts.

According to the viewpoint of the present invention, there is provided a lithium secondary battery comprising a cathode; an anode; a separator; and a gel polymer electrolyte, wherein the gel polymer electrolyte comprises an acrylate-based polymer, and the battery The charging voltage is in the range of 4.3 volts to 5.0 volts.

According to another aspect of the present invention, a method of fabricating a lithium secondary battery is provided, the method comprising inserting an electrode assembly including a cathode, an anode, and a separator interposed between the cathode and the anode into a battery can; And injecting a composition for a gel polymer electrolyte into the battery can and polymerizing the composition to form a gel polymer electrolyte, wherein the composition for the gel polymer electrolyte comprises an electrolyte solution solvent, ionizable Lithium salt, and monomer having 2 to 6 acrylate groups.

A lithium secondary battery according to a specific embodiment of the present invention has excellent life characteristics and capacitance characteristics even at a high voltage charge of 4.3 volts or more.

1 illustrates a capacitance diagram of lithium secondary batteries fabricated in Examples 1 and 2 and Comparative Examples 1 and 2 when the battery was charged at a high voltage of 4.3 volts.

Hereinafter, the present invention will be described in more detail to more clearly understand the present invention.

It will be understood that the words or nouns used in the specification and the scope of the patent application should not be interpreted in the meanings defined in the commonly used dictionary. It will be further understood that the vocabulary or noun should be based on the inventor's right to define a vocabulary or noun to best explain the principles of the present invention to have relevance to the present invention. The meaning of the meaning in the context of technical and technical ideas is explained.

A lithium secondary battery according to a specific embodiment of the present invention is a high voltage lithium secondary battery including a cathode; an anode; a separator; and a gel polymer electrolyte, wherein the gel polymer electrolyte includes an acrylate-based A polymer, and the battery has a charging voltage in the range of 4.3 volts to 5.0 volts.

The gel polymer electrolyte can be formed by polymerizing a composition including an electrolyte solution solvent, an ionizable lithium salt, and a monomer having 2 to 6 acrylate groups.

The monomer having 2 to 6 acrylate groups may be a branched monomer, and may be, for example, selected from the group consisting of bis(trimethylol)propane tetraacrylate, dipentaerythritol pentaacrylate, and dixin. Any of the group consisting of pentaerythritol hexaacrylate, or a mixture of two or more thereof.

The monomer content is from 0.1% by weight to 10% by weight, preferably from 0.5% by weight to 5% by weight, based on the total weight of the composition for the gel polymer electrolyte.

According to a specific embodiment of the invention, the ionizable lithium salt is included in the electrolyte, for example, may be selected from the group consisting of LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiN (C ₂ F ₅ SO _{2 ) 2, LiN (CF 3 SO} 2) 2, CF 3 SO 3 Li, any one of (CF ₃ SO _{2) 3,} and the group consisting of LiC ₄ BO ₈ LiC one of the, or one of two or more a mixture of people. However, the invention is not limited thereto.

Any electrolyte solution solvent typically used for an electrolyte solution of a lithium secondary battery can also be used as an electrolyte solution for use in the present invention without limitation. The liquid solvent, for example, an ether, an ester, a guanamine, a linear carbonate, or a cyclic carbonate may be used singly or in the form of a mixture of two or more thereof.

Among these materials, a cyclic carbonate, a linear carbonate, or a mixture thereof (carbonate mixture) is typically included. Specific examples of the cyclic carbonate may include those selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butane carbonate, and 1,2-carbonic acid. Any one of the group consisting of pentanic acid ester, 2,3-pentane diester carbonate, vinylene carbonate, and a halide thereof, or a mixture of two or more thereof. Specific examples of the linear carbonate may also be selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), and methyl propyl carbonate. Any of a group consisting of (MPC), and ethyl propyl carbonate (EPC), or a mixture of two or more thereof. However, the invention is not limited thereto.

In particular, since propylene carbonate and ethylene carbonate (as a cyclic carbonate in a carbonate-based electrolyte solution solvent) are high-viscosity organic solvents and have a high dielectric constant, propylene carbonate and Ethylene carbonate readily dissociates the lithium salt in the electrolyte solution. Thus, propylene carbonate and ethylene carbonate can be used. Since the above-mentioned cyclic carbonate is mixed with a low-viscosity, low-dielectric linear carbonate such as ethyl methyl carbonate, diethyl carbonate, and dimethyl carbonate in an appropriate ratio, a highly conductive electrolyte solution is produced. Therefore, for example, propylene carbonate and ethylene carbonate can be used.

Choose free methyl acetate, ethyl acetate, propyl acetate, C Any of the group consisting of methyl ester, ethyl propionate, γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone, Or a mixture of two or more of them may also be used as an ester in an electrolyte solution solvent. However, the invention is not limited thereto.

According to a specific embodiment of the present invention, the composition for the gel polymer electrolyte may further include a polymerization initiator, and a typical polymerization initiator known in the art may be used as a polymerization initiator.

Non-limiting examples of the polymerization initiator may be organic peroxides or hydroperoxides such as benzamidine peroxide, acetam peroxide, dilauroside peroxide, di(tertiary butyl) peroxidation. , peroxy-2-ethylhexanoate tert-butyl ester, cumyl hydroperoxide, and hydroperoxide, and azo compounds such as 2,2'-azobis(2-cyano) Butane), 2,2'-azobis(methylbutyronitrile), 2,2'-azobis(iso-butyronitrile) (AIBN), and 2,2'-azobis ( Dimethylvaleronitrile) (AMVN). However, the invention is not limited thereto.

The polymerization initiator can be dissociated in the battery by heat, and can be used for non-limiting examples, at a temperature of 30 ° C to 100 ° C, or can be dissociated at room temperature (5 ° C to 30 ° C) to form free radicals, and freely The base polymerization reaction is carried out with a monomer having 2 to 6 acrylate groups to form a gel polymer electrolyte.

The polymerization initiator is used in an amount of from 0.01% by weight to 2% by weight based on the total weight of the composition for the gel polymer electrolyte. When the amount of the polymerization initiator is more than 2% by weight, the gelation is too rapid during the injection of the composition for the gel polymer electrolyte into the battery, or The unreacted polymerization initiator is left behind and has a negative impact on battery performance. On the other hand, when the amount of the polymerization initiator is less than 0.01% by weight, gelation cannot be smoothly performed.

In addition to the foregoing components, the electrolyte according to particular embodiments of the present invention may optionally include other additives known in the art.

According to a specific embodiment of the present invention, the present invention also provides a method of manufacturing a lithium secondary battery, comprising: inserting an electrode assembly including a cathode, an anode, and a separator interposed between the cathode and the anode into a battery case And injecting a composition for a gel polymer electrolyte into the battery can and polymerizing the composition to form a gel polymer electrolyte, wherein the composition for the gel polymer electrolyte comprises an electrolyte solution solvent, An ionized lithium salt, and a monomer having 2 to 6 acrylate groups.

According to a specific embodiment of the present invention, the gel polymer electrolyte can be formed by polymerizing the aforementioned composition for a gel polymer electrolyte by a typical method known according to this technique. For example, the in situ polymerization of the composition of the gel polymer electrolyte used in the secondary battery forms an electrolyte.

According to an exemplary embodiment of the present invention, the method may include (a) inserting an electrode assembly including a cathode, an anode, and a separator interposed between the cathode and the anode into a battery can, and (b) using A composition of the gel polymer electrolyte is injected into the battery can and the composition is polymerized to form a gel polymer electrolyte.

The in situ polymerization in a lithium secondary battery can be carried out by thermal polymerization. In this case, the polymerization time is about 2 minutes to 12 hours. In the range of the time, the thermal polymerization temperature is in the range of 30 ° C to 100 ° C.

Upon completion of gelation by polymerization, a gel polymer electrolyte is formed, whereby the gel polymer formed is uniformly impregnated with a liquid electrolyte solution in which the electrolyte salt dissociates in the solvent of the electrolyte solution.

The electrode of the lithium secondary battery according to a specific embodiment of the present invention can be manufactured by a typical method known from the art. For example, a binder, a conductive agent, and a dispersing agent, if necessary, and a solvent are mixed with an electrode active material and stirred to prepare a slurry, and then the surface of the metal current collector is coated with the slurry and pressed. Thereafter, an electrode is produced by drying the metal current collector.

According to a specific embodiment of the present invention, any compound can be used as the cathode active material in the cathode without limitation as long as it can be used at a high voltage of 4.3 volts to 5.0 volts and can reversibly interpose/disengage lithium.

Specifically, the cathode active material includes a transition metal oxide selected from the group consisting of spinel lithium (which has a hexagonal layered salt structure and high capacitance characteristics, an olivine structure, a cubic structure), V ₂ O ₅ , TiS, and MoS. Any of the group consisting of, or a mixture of two or more thereof.

More specifically, the cathode active material, for example, may include any one selected from the group consisting of compounds of Chemical Formulas 1 to 3; or a mixture of two or more thereof.

<Chemical Formula 1> Li[Li _x Ni _a Co _b Mn _c ]O ₂ (where 0<x 0.3, 0.3 c 0.7,0<a+b<0.5, and x+a+b+c=1); <Chemical Formula 2>LiMn _2-x M _x O ₄ (wherein M is selected from nickel (Ni), cobalt (Co), One or more elements of the group consisting of iron (Fe), phosphorus (P), sulfur (S), zirconium (Zr), titanium (Ti), and aluminum (Al), and 0 < x 2); <Chemical Formula 3> Li _1+a Co _x M _1-x AX ₄ (wherein M is selected from the group consisting of Al, magnesium (Mg), Ni, Co, manganese (Mn), Ti, gallium (Ga), copper ( One or more elements of the group consisting of Cu), vanadium (V), niobium (Nb), Zr, cerium (Ce), indium (In), zinc (Zn), and yttrium (Y), X-based One or more elements in the group consisting of free oxygen (O), fluorine (F), and nitrogen (N), A system P, S or a mixed element thereof, 0 a 0.2, and 0.5 x 1).

The cathode active material conforms to 0.4 in Chemical Formula 1. c 0.7 and 0.2 a+b<0.5, and is selected from any one of the group consisting of LiNi _0.5 Mn _1.5 O ₄ , LiCoPO ₄ , and LiFePO ₄ , or a mixture of two or more thereof.

In the anode according to a specific embodiment of the present invention, a carbon material, lithium metal, ruthenium, or tin, which can intercalate and detach from lithium ions, can be basically used as an anode active material. For example, a carbon material and both low crystalline carbon and high crystalline carbon can be used as the carbon material. Representative examples of low crystalline carbon may be soft carbon and hard carbon, and representative examples of high crystalline carbon may be natural graphite, Kish graphite, pyrolytic carbon, metastable phase asphalt-based carbon fiber, metastable phase carbon particulate, and Stable phase asphalt, and high temperature sintered carbon (such as petroleum or coal tar pitch) Coke).

The slurry is prepared by mixing and stirring an anode or a cathode active material, a binder, a solvent, and a conductive agent, and a dispersant which is typically used, if necessary. Thereafter, an anode or a cathode is prepared by coating a current collector with the slurry and pressing the coated current collector.

Various types of binder polymers, such as vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyvinyl alcohol, carboxymethyl Cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylate, ethylene-propylene-diene monomer (EPDM) Sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, and various copolymers can be used as binders.

Typical porous polymer membranes can also be used as typical separators, for example, from polyolefin-based polymers (eg, ethylene homopolymers, propylene homopolymers, ethylene/butene copolymers, ethylene/hexene copolymers). A porous polymer film made of an ethylene/methacrylate copolymer can be used alone or as a separator. Further, a typical porous non-woven fabric, for example, a high-melting glass fiber or a non-woven fabric of polyethylene terephthalate fibers can be used. However, the invention is not limited thereto.

The shape of the lithium secondary battery of the present invention is not particularly limited, and may be, for example, a cylindrical type, a sputum type, a pouch type, or a coin type using a can.

In the following, the hair will be described in detail according to a specific example. Bright. However, the invention may be embodied in many different forms and should not be limited to the specific embodiments set forth herein. Rather, these specific embodiments are presented so that this disclosure will be thorough and complete.

Instance

Hereinafter, the present invention will be described in more detail based on examples and experimental examples. However, the invention is not limited thereto.

Example 1 <Manufacture of a composition for a gel polymer electrolyte>

The LiPF ₆ concentration was made 1M by dissolving LiPF ₆ in a non-aqueous electrolyte solution of ethylene carbonate (EC) to ethyl carbonate (EMC) in a volume ratio of 1:2. 5 parts by weight of bis(trimethylol)propane tetraacrylate and 0.25 parts by weight of tert-butyl peroxy-2-ethylhexanoate as a polymerization initiator by adding 100 parts by weight of the electrolyte solution A composition for a gel polymer electrolyte is prepared.

<Manufacture of coin type secondary battery> Cathode manufacturing

By using 94% by weight of Li[Li _0.29 Ni _0.14 Co _0.11 Mn _0.46 ]O ₂ (as a cathode active material), 3% by weight of carbon black (as a conductive agent), and 3% by weight of polyvinylidene fluoride (PVdF) ( As a binder, it was added to N-methyl-2-pyrrolidone (NMP) as a solvent to prepare a cathode mixture slurry. An approximately 20 micrometer thick aluminum (Al) film as a cathode current collector was coated with the cathode mixture slurry and dried, after which the Al film was rolled to obtain a cathode.

Manufacture of anode

An anode mixture slurry was prepared by adding 96% by weight of carbon powder as an anode active material, 3% by weight of PVdF as a binder, and 1% by weight of carbon black as a conductive agent to NMP as a solvent. A 10 micron thick copper (Cu) film as an anode current collector was coated with an anode mixture slurry and dried, after which the Cu film was rolled to obtain an anode.

Battery manufacturing

The battery was assembled using a separator formed of a cathode, an anode, and a polypropylene/polyethylene/polypropylene (PP/PE/PP) three-layer separator, and the composition for the gel polymer electrolyte was injected into the assembled battery. Thereafter, a secondary battery was produced by heating the assembled battery at 80 ° C for 2 minutes to 30 minutes in a nitrogen atmosphere.

Example 2

A secondary battery was fabricated in the same manner as in Example 1, but in the production of the composition for the gel polymer electrolyte of Example 1, used Dipentaerythritol pentaacrylate replaces bis(trimethylol)propane tetraacrylate.

Comparative example 1

A secondary battery was fabricated in the same manner as in Example 1, except that in the production of the composition for the gel polymer electrolyte of Example 1, bis(trimethylol)propane tetraacrylate and peroxy-2 were not used. - Tert-butyl butyl hexanoate.

Comparative example 2

A secondary battery was fabricated in the same manner as in Example 1, except that in the preparation of the cathode of Example 1, LiCoO _{2 was} used as the cathode active material.

Experimental example

The lithium secondary batteries (battery capacitance: 4.3 mAh) manufactured in Examples 1 and 2 and Comparative Examples 1 and 2 were charged to 4.3 volts at a constant current of 0.7 C at 55 °C. Thereafter, the lithium secondary battery was charged at a constant voltage of 4.3 volts, and the charging was stopped when the charging current reached 0.215 milliamperes. After the battery was allowed to stand for 10 minutes, the battery was discharged at a constant current of 0.5 C to a voltage of 3.0 volts. Repeat the charging and discharging to 30 cycles and then measure the battery capacitance. The result is shown in Fig. 1.

Specifically, as shown in FIG. 1, the battery capacities of Examples 1 and 2 and Comparative Examples 1 and 2 were almost similar to each other up to about the 5th cycle. However, the capacitances of Comparative Examples 1 and 2 rapidly decreased after about the fifth cycle. In particular, regarding Comparative Example 2 using LiCoO ₂ as a cathode active material, the capacitance after the fifth cycle was remarkably lowered, and the capacitance in the 30th cycle was close to 0 mAh. On the other hand, Examples 1 and 2 exhibited excellent capacitance even at a high voltage to the 30th cycle, and the exhibited capacitance was 2 to 4 times or more of Comparative Examples 1 and 2.

Therefore, the high voltage charging at 4.3 volts was understood, and after 30 cycles, the capacitance of the batteries fabricated in Examples 1 and 2 was significantly improved as compared with the case of the batteries fabricated in Comparative Examples 1 and 2.

Industrial applicability

Since the lithium secondary battery according to the embodiment of the present invention has excellent life characteristics and capacitance characteristics even if the battery is charged at a high voltage of 4.3 volts or higher, it is suitable for a secondary battery.

Claims (16)

A lithium secondary battery comprising: a cathode; an anode; a separator; and a gel polymer electrolyte, wherein the gel polymer electrolyte comprises an acrylate-based polymer, and the battery has a charging voltage of 4.3 volts to Within the range of 5.0 volts. The lithium secondary battery of claim 1, wherein the gel polymer electrolyte is composed of a polymer comprising an electrolyte solution solvent, an ionizable lithium salt, and a monomer having 2 to 6 acrylate groups. Formed by matter. The lithium secondary battery of claim 1, wherein the cathode comprises a cathode active material selected from any one of the group consisting of compounds of Chemical Formulas 1 to 3; or a mixture of more: <Chemical Formula 1>Li[Li _x Ni _a Co _b Mn _c ]O ₂ (where 0<x 0.3, 0.3 c 0.7,0<a+b<0.5, and x+a+b+c=1); <Chemical Formula 2>LiMn _2-x M _x O ₄ (wherein M is selected from nickel (Ni), cobalt (Co), One or more elements of the group consisting of iron (Fe), phosphorus (P), sulfur (S), zirconium (Zr), titanium (Ti), and aluminum (Al), and 0 < x 2); <Chemical Formula 3> Li _1+a Co _x M _1-x AX ₄ (wherein M is selected from the group consisting of Al, magnesium (Mg), Ni, Co, manganese (Mn), Ti, gallium (Ga), copper ( One or more elements of the group consisting of Cu), vanadium (V), niobium (Nb), Zr, cerium (Ce), indium (In), zinc (Zn), and yttrium (Y), X-based One or more elements in the group consisting of free oxygen (O), fluorine (F), and nitrogen (N), A system P, S or a mixed element thereof, 0 a 0.2, and 0.5 x 1). A lithium secondary battery according to claim 3, wherein the cathode active material conforms to 0.4 in Chemical Formula 1. c 0.7 and 0.2 a+b<0.5, and is selected from any one of the group consisting of LiNi _0.5 Mn _1.5 O ₄ , LiCoPO ₄ , and LiFePO ₄ , or a mixture of two or more thereof. A lithium secondary battery according to claim 2, wherein the single system is selected from the group consisting of bis(trimethylol)propane tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate. Any of a group consisting of, or a mixture of two or more of them. A lithium secondary battery according to claim 2, wherein the monomer content is from 0.1% by weight to 10% by weight based on the total weight of the composition. A lithium secondary battery according to claim 2, wherein the lithium salt is selected from the group consisting of LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ Any of the group consisting of SO ₂ ) ₂ , CF ₃ SO ₃ Li, LiC(CF ₃ SO ₂ ) ₃ , and LiC ₄ BO ₈ , or a mixture of two or more thereof. A lithium secondary battery according to claim 2, wherein the electrolyte solution solvent is a linear carbonate, a cyclic carbonate, or a mixture thereof. The lithium secondary battery of claim 8, wherein the linear carbonate comprises a solvent selected from the group consisting of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, and Any of the group consisting of propyl carbonate, or a mixture of two or more thereof. The lithium secondary battery of claim 8, wherein the cyclic carbonate comprises a solvent selected from the group consisting of ethylene carbonate, propylene carbonate, 1,2-butyl dicarbonate, 2,3-butyl dicarbonate, Any one of the group consisting of 1,2-pentane dicarboxylate, 2,3-pentane dicarbonate, vinylene carbonate, and a halide thereof, or two or more thereof a mixture. A lithium secondary battery according to claim 1, wherein the anode comprises a carbon material anode active material. A method of manufacturing a lithium secondary battery, the method comprising: inserting an electrode assembly including a cathode, an anode, and a separator interposed between the cathode and the anode into a battery case; and a gel polymer electrolyte a composition is injected into the battery can and polymerized to form a gel polymer electrolyte, wherein the composition for the gel polymer electrolyte comprises an electrolyte solution solvent, an ionizable lithium salt, and 2 to 6 Acrylate based monomers. The method of claim 12, wherein the composition for the gel polymer electrolyte further comprises a polymerization initiator. The method of claim 12, wherein the polymerization is carried out at a temperature ranging from 30 ° C to 100 ° C. The method of claim 12, wherein the single system is selected from the group consisting of bis(trimethylol)propane tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate. Any of the groups, or a mixture of two or more of them. The method of claim 12, wherein the cathode comprises a cathode active material selected from the group consisting of compounds of Chemical Formulas 1 to 3; or two or more of them Mixture: <Chemical Formula 1> Li[Li _x Ni _a Co _b Mn _c ]O ₂ (where 0<x 0.3, 0.3 c 0.7,0<a+b<0.5, and x+a+b+c=1); <Chemical Formula 2>LiMn _2-x M _x O ₄ (wherein M is selected from nickel (Ni), cobalt (Co), One or more elements of the group consisting of iron (Fe), phosphorus (P), sulfur (S), zirconium (Zr), titanium (Ti), and aluminum (Al), and 0 < x 2); <Chemical Formula 3> Li _1+a Co _x M _1-x AX ₄ (wherein M is selected from the group consisting of Al, magnesium (Mg), Ni, Co, manganese (Mn), Ti, gallium (Ga), copper ( One or more elements of the group consisting of Cu), vanadium (V), niobium (Nb), Zr, cerium (Ce), indium (In), zinc (Zn), and yttrium (Y), X-based One or more elements in the group consisting of free oxygen (O), fluorine (F), and nitrogen (N), A system P, S or a mixed element thereof, 0 a 0.2, and 0.5 x 1).