KR101630162B1 - Positive-electrode Active Material of Li Secondary Battery with Improved Operating Life and The Fabrication Method Thereof - Google Patents

Abstract

The cathode active material for a lithium secondary battery according to the present invention comprises a spinel-type lithium metal oxide surface-modified with an alkali metal-substituted zeolite. The method for preparing a cathode active material for a lithium secondary battery according to the present invention comprises the steps of: a) Based lithium metal oxide; And b) heat treating the mixture of step a).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive active material for a lithium secondary battery,

The present invention relates to a positive electrode active material for a lithium secondary battery and a method for producing the same, and more particularly, to a positive electrode active material for a lithium secondary battery having an excellent operating life and a method for manufacturing the same.

Recently, the oil crisis has become serious due to unstable oil, depletion of fossil fuel resources, and environmental problems caused by CO ₂ emissions. It is a global consensus that the solution of energy problems is a solution to environmental problems. , Japan, and other developed countries are rapidly expanding their R & D and energy storage - conversion - transportation system technology market to convert automobile transportation energy sources from fossil fuel to electrical energy.

In particular, hybrid electric vehicles (HEVs) are considered to be the most dramatic alternative to energy efficiency. Japan has already secured its position as a leader in the global automobile industry, including Toyota and Honda. Major automakers such as the US and Europe are also conducting R & D to narrow the gap in technology.

Hybrid electric vehicles (HEV) were HEVs equipped with Ni-MH batteries, but since 2009, HEVs equipped with lithium secondary batteries have been released.

Lithium secondary batteries are suitable systems for HEV in terms of high output characteristics, energy density and energy efficiency, but also have problems such as system safety and proper price assurance. In particular, it is essential to secure an excellent operating life characteristic in a lithium secondary battery for HEV. In order to satisfy the above requirements, development or performance of a new material for a cathode material, which is the most important core material of lithium secondary batteries and has a large cost- Improvement is absolutely necessary.

Currently spinel type lithium manganese metal oxide such as Korean Laid-Open Patent Application No. 2013-0040074 can be exemplified as a typical positive electrode active material of HEV high output battery. Spinel type lithium manganese metal oxide is advantageous in that it is inexpensive and has no toxicity, HEV and other large-capacity batteries, as well as structural stability in which lithium ions can be inserted and desorbed three-dimensionally unlike Ni-based and Co-based active materials, which are layered compounds, As a cathode material. However, performance degradation due to deterioration in high temperature cycles remains a problem to be solved.

Korean Patent Publication No. 2013-0040074

Disclosed is a lithium secondary battery which is excellent in price competitiveness, has no toxicity, has a high output characteristic suitable for an HEV, has excellent structural stability in insertion and desorption of lithium ions, has a stable charge / discharge cycle characteristic The present invention provides a cathode active material for a lithium secondary battery, and more particularly, to provide a cathode active material for a lithium secondary battery, wherein spinel-based lithium metal oxide is used as a main material and high temperature deterioration is prevented.

The cathode active material for a lithium secondary battery according to the present invention comprises a spinel-type lithium metal oxide surface-modified with an alkali metal-substituted zeolite.

In the cathode active material according to an embodiment of the present invention, the alkali metal may be at least one element selected from lithium (Li), sodium (Na), potassium (K), rubidium (Rb) and cesium (Cs).

In the cathode active material according to one embodiment of the present invention, the olite may be zeolite Y.

The cathode active material according to an embodiment of the present invention may contain 0.1 to 10 mol% of zeolite and 99.9 to 90 mol% of lithium metal oxide.

In the cathode active material according to one embodiment of the present invention, the lithium metal oxide may be a material according to the following formula (1).

(Formula 1)

Li _{1 + x} Mn _2-y M _y O ₄

X is a real number of 0? X? 0.2, y is a real number of 0? Y? 0.7, and M is a divalent or trivalent metal.

The present invention includes a lithium secondary battery containing the above-mentioned cathode active material.

A method for producing a cathode active material for a lithium secondary battery according to the present invention comprises the steps of: a) mixing an alkali metal-substituted zeolite and a spinel-type lithium metal oxide; And b) heat treating the mixture of step a).

In the method for producing a cathode active material for a lithium secondary battery according to an embodiment of the present invention, in step a), 0.1 to 10 mol% of zeolite and 99.9 to 90 mol% of lithium metal oxide may be mixed.

In the method of manufacturing a cathode active material for a lithium secondary battery according to an embodiment of the present invention, the heat treatment may be performed at a temperature of 400 to 900 DEG C in the presence of oxygen.

A method for producing a cathode active material for a lithium secondary battery according to an embodiment of the present invention comprises the step of adding zeolite to an ion exchange solution containing alkali metal ions at a concentration of 0.01 to 2 M and heated to 30 to 80 캜 for 4 to 8 hours Impregnated zeolite to prepare an alkali metal-substituted zeolite.

The cathode active material according to the present invention is excellent in price competitiveness, has no toxicity, has a high output characteristic suitable for HEV, has excellent structural stability in insertion and desorption of lithium ions, and is stable in charge / discharge Cycle characteristics, and has an advantage of having excellent cell capacity.

FIG. 1 is a graph showing the X-ray diffraction results of the cathode active material prepared in Example 1,
FIG. 2 is a graph showing the X-ray diffraction results of the cathode active material prepared in Example 2,
3 is a graph showing the X-ray diffraction results of the cathode active material prepared in Example 3,
FIG. 4 is a graph showing X-ray diffraction results of the cathode active material prepared in Comparative Example,
5 is a scanning electron microscope (SEM) image of the cathode active material prepared in Example 1,
6 is a scanning electron microscope (SEM) image of the cathode active material prepared in Example 2,
7 is a scanning electron micrograph of the cathode active material prepared in Example 3,
8 is a scanning electron microscope (SEM) photograph of the cathode active material prepared in Comparative Example,
FIG. 9 is a diagram showing the measurement of the high-temperature charge / discharge cycle characteristics of the lithium secondary battery manufactured in Example 2 and the comparative example.

Hereinafter, the cathode active material of the present invention and its production method will be described in detail. Hereinafter, the technical and scientific terms used herein will be understood by those skilled in the art without departing from the scope of the present invention. Descriptions of known functions and configurations that may be unnecessarily blurred are omitted.

As a result of long-term research to improve the high-temperature charge-discharge cycle characteristics of spinel-type lithium metal oxides, the present applicant surprisingly found that when the spinel-based lithium metal oxide is surface-modified with an alkali metal-substituted zeolite, Not only remarkably improved but also the reversible capacity of the active material was increased, leading to the filing of the present invention.

The cathode active material according to the present invention is a cathode active material for a lithium secondary battery and includes a spinel-type lithium metal oxide surface-modified with an alkali metal-substituted zeolite.

The cathode active material according to the present invention is a zeolite substituted with an alkali metal. As the spinel-type lithium metal oxide is surface-modified, deterioration of the spinel-type lithium metal oxide at high temperature is prevented, , It is possible to have a higher battery capacity than the spinel type lithium metal oxide.

In the cathode active material according to an embodiment of the present invention, the spinel-type lithium metal oxide surface-modified with an alkali metal-substituted zeolite may mean a structure in which the surface of the spinel-type lithium metal oxide is surrounded with an alkali metal-substituted zeolite .

In detail, the cathode active material according to an embodiment of the present invention may be a composite particle comprising a coating layer of alkali metal-substituted zeolite coated on the surface of spinel-type lithium metal oxide particles and spinel-type lithium metal oxide particles.

The cathode active material according to an embodiment of the present invention may contain 0.1 to 10 mol% of zeolite and 99.9 to 90 mol% of lithium metal oxide. In terms of effective prevention of high temperature deterioration and smooth insertion and desorption of lithium ions, the cathode active material may contain 1 to 10 mol% of zeolite and 99 to 90 mol% of lithium metal oxide.

In the cathode active material according to one embodiment of the present invention, the composite particles including the coating layer of the spinel-based lithium metal oxide particles and the alkali-metal-substituted zeolite may have an average diameter of 1 μm to 30 μm. That is, the cathode active material according to one embodiment of the present invention may have a particle size of 1 μm to 30 μm in average diameter and a coating layer of zeolite formed on the surface of the lithium metal oxide.

Specifically, the cathode active material according to an embodiment of the present invention may have a bimodal distribution in a particle size distribution.

As described below, the cathode active material according to one embodiment of the present invention can be produced by mixing an alkali metal-substituted zeolite and a spinel-type lithium metal oxide and then heat-treating the mixture. At this time, densification and grain growth of the spinel-based lithium metal oxide can be remarkably prevented by the alkali metal-substituted zeolite. Accordingly, the cathode active material according to an embodiment of the present invention may have a bimodal distribution of relatively small particles and relatively large particles on a particle size distribution. In such a bimodal distributed cathode active material, the cathode active material particles having a relatively small size can be positioned in the void space between the cathode active material particles having a relatively large size, thereby improving the packing density of the cathode active material layer , Thus having improved bulk density and discharge capacity.

In the cathode active material according to one embodiment of the present invention, the alkali metal of the alkali metal-substituted zeolite is selected from one or more selected from lithium (Li), sodium (Na), potassium (K), rubidium (Rb) and cesium Metal. In order to more effectively prevent the deterioration of the spinel-based lithium metal oxide at a high temperature, the alkali metal may be rubidium, cesium or rubidium and cesium, more preferably cesium.

At this time, the alkali metal-substituted zeolite is added to an ion exchange solution containing alkali metal ions at a concentration of 0.01 to 2M and heated to 30 to 80 캜, and 1 to 80 parts by weight of zeolite based on 100 parts by weight of the ion exchange solution for 4 to 8 hours Impregnated < / RTI >

In the cathode active material according to an embodiment of the present invention, the spinel-based lithium metal oxide may be a spinel-based lithium manganese metal oxide, and more specifically, the spinel-based lithium metal oxide may be a material defined by the following formula (1).

(Formula 1)

Li _{1 + x} Mn _2-y M _y O ₄

X is a real number of 0? X? 0.2, y is a real number of 0? Y? 0.7, and M is a divalent or trivalent metal. In detail, in the spinel-based lithium metal oxide according to Formula 1, M, which is a divalent or trivalent metal, is one or more of Mg, Fe, Co, Ni, Cu, Zn, Cd, The metal (M) can inhibit the elution of manganese and improve the lifetime. Also, in order to minimize the irreversible capacity decrease and to have a high energy density, x may be a real number less than 0.2. In order to suppress the manganese dissolution and improve the lifetime and to minimize the initial capacity decrease by M, y is less than 0.2 It can be a mistake.

The spinel-based lithium metal oxide according to Formula (1) is excellent in price competitiveness, has no toxicity, has a high output characteristic suitable for HEV, and has excellent structural stability in insertion and desorption of lithium ions.

Zeolite A, zeolite X, zeolite Y, zeolite L, ZSM-5, beta-zeolite, ZSM-8, ZSM-11, or a mixture thereof may be used in the positive electrode active material according to an embodiment of the present invention. The zeolite substituted with an alkali metal may be zeolite Y. < RTI ID = 0.0 > The zeolite Y not only has excellent thermal stability, but also has a high specific surface area of up to 600 m ² / g, which can improve the contact area of the battery with the electrolytic solution, and the large number of pores 12-member oxygen ring, and has three-dimensional pores to allow smooth migration of lithium ions.

The present invention includes a lithium secondary battery containing the above-mentioned cathode active material.

Specifically, the present invention includes a lithium secondary battery including a positive electrode for a lithium secondary battery containing the positive electrode active material described above, and a lithium secondary battery having such a positive electrode.

The positive electrode for a lithium secondary battery according to an embodiment of the present invention may include a positive electrode active material layer positioned on the current collector and current collector. The active material layer may be located on at least one surface of the current collector and may be located in contact with the current collector.

The lithium secondary battery according to an embodiment of the present invention includes a lithium ion secondary battery or a lithium polymer secondary battery, and may further include a cathode, an electrolyte, and a separation membrane together with the anode.

The lithium secondary battery according to an embodiment of the present invention may have a structure in which an electrode stacked body in which a plurality of positive and negative electrodes opposite to each other with a separator interposed therebetween is impregnated with an electrolyte.

Specifically, the lithium secondary battery according to an embodiment of the present invention includes an electrode assembly in which an anode and a cathode opposite to each other with a separator interposed therebetween are alternately stacked at least once, an electrolyte in which the electrode assembly is impregnated, The battery case may include a battery case.

Each anode of the electrode assembly may be connected in series, parallel, or series-parallel, and each cathode may be connected in series, parallel, or series-parallel. At this time, the anode may include a current collector and a cathode active material layer containing the cathode active material on the current collector, and may include a non-cathode active material layer on which the cathode active material layer is not formed. The negative electrode may further include a current collector and a negative electrode active material layer containing the negative electrode active material on the current collector, and may include an uncoated portion in which the negative electrode active material layer is not formed. Electrical connection between each anode or each cathode of the electrode assembly can be accomplished through this igniter.

In the electrode assembly, the current collector of each anode and / or each cathode may be a foam, a film, a mesh, or the like of graphite, graphene, titanium, copper, platinum, aluminum, nickel, silver, gold, a mesh, a felt or a perforated film.

Electrode Assembly The negative electrode active material of each negative electrode can be used as an active material conventionally used for a negative electrode of a lithium secondary battery. As a non-limiting example, the negative electrode active material may be at least one selected from the group of negative electrode active materials of lithium (metal lithium), graphitizable carbon, hard graphitizable carbon, graphite, silicon and lithium-titanium oxide.

In the electrode assembly, the separation membrane positioned between the anodes and the cathodes adjacent to each other may be different or the same depending on positions in accordance with the stacking direction of the anodes and the cathodes, and in order to prevent a short circuit between the cathodes and the anodes in a conventional lithium secondary battery, A separator used as a separator is sufficient. As a non-limiting example, the separation membrane may be a material selected from one or more of polyethylene, polypropylene, polyolefin, and polyester, and may be a microporous membrane structure.

The electrolyte in which the electrode assembly is impregnated may be a conventional aqueous or non-aqueous electrolyte capable of smoothly conducting lithium ions involved in charging and discharging of the battery and maintaining battery characteristics for a long period of time in a conventional lithium secondary battery. As a non-limiting example, the electrolyte may be a non-aqueous electrolyte, and the non-aqueous electrolyte may include a non-aqueous solvent and a lithium salt. As a non-limiting example, the lithium salt contained in the electrolyte may be a lithium cation and a cation selected from the group consisting of NO ₃ ^- , N (CN) ₂ ^- , BF ₄ ^- , ClO ₄ ^- , PF ₆ ^- , (CF ₃ ) ₂ PF ₄ ^{- _{3) 3 PF 3 -, (}} CF 3) 4 PF 2 -, (CF 3) 5 PF -, (CF 3) 6 P -, CF 3 SO 3 -, CF 3 CF 2 SO 3 -, (CF 3 SO ^{_{2) 2 N -, (FSO}} 2) 2 N -, CF 3 CF 2 (CF 3) 2 CO -, (CF 3 SO 2) 2 CH -, (SF 5) 3 C -, (CF 3 SO 2) (CF ₃ CF ₂ SO ₂ ) ₂ N ^- , which provide at least one anion selected from the group consisting of ₃ C ^- , CF ₃ (CF ₂ ) ₇ SO ₃ ^- , CF ₃ CO ₂ ^- , CH ₃ CO ₂ ^- and SCN ^- It can be a salt. The solvent of the electrolyte is selected from the group consisting of ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, Dimethyl carbonate, diethyl carbonate, di (2,2,2-trifluoroethyl) carbonate, dipropyl carbonate, dibutyl carbonate, ethyl methyl carbonate, 2,2,2-trifluoroethyl methyl carbonate, methyl propyl carbonate , Ethyl propyl carbonate, 2,2,2-trifluoroethyl propyl carbonate, methyl formate, ethyl formate, propyl formate, butyl formate, dimethyl ether, diethyl ether, di Propyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, methyl acetate, ethyl acetate, propyl acetate, Butyrate, butyl butyrate, gamma -butyrolactone (gamma-butyrolactone), ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, butyrolactone, 2-methyl- gamma -butyrolactone, 3-methyl- gamma -butyrolactone, 4-methyl- gamma -butyrolactone, gamma -thiobutyrolactone, ? -valerolactone,? -valerolactone,? -caprolactone,? -caprolactone,? -propiolactone (? -caprolactone,? -caprolactone, propiolactone), tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, trimethylphosphate, triethylphosphate, tris (2-chloroethyl) 2-trifluoroethyl) phosphate, tripropyl phosphate, triisopropyl But are not limited to, sulfates, triesters, tributyl phosphate, trihexyl phosphate, triphenyl phosphate, tritolyl phosphate, methyl ethylene phosphate, ethyl ethylene phosphate, dimethyl sulfone, ethyl methyl sulfone, methyl trifluoromethyl sulfone, Sulfone, methylpentafluoroethylsulfone, ethyl pentafluoroethylsulfone, di (trifluoromethyl) sulfone, di (pentafluoroethyl) sulfone, trifluoromethylpentafluoroethylsulfone, trifluoromethyl nonafluoro One or more selected solvents selected from butyl sulfone, pentafluoroethyl nonafluorobutyl sulfone, sulfolane, 3-methyl sulfolane, 2-methyl sulfolane, 3-ethyl sulfolane and 2- .

A method for producing a cathode active material for a lithium secondary battery according to the present invention comprises the steps of: a) mixing an alkali metal-substituted zeolite and a spinel-type lithium metal oxide; And b) heat treating the mixture of step a).

The method for producing a cathode active material for a lithium secondary battery according to the present invention is characterized in that an extremely easy and simple process of mixing an alkali metal-substituted zeolite and a spinel-type lithium metal oxide and performing a heat treatment prevents high temperature deterioration, It is possible to manufacture a positive electrode active material having an excellent battery capacity.

The alkali-metal-substituted zeolite mixed in step a) is added to an ion-exchange liquid containing alkali metal ions in a concentration of 0.01 to 2 M and heated to 30 to 80 캜, in an amount of 1 to 80 parts by weight based on 100 parts by weight of the ion- Of 10 to 50 parts by weight, more specifically 10 to 30 parts by weight of zeolite for 4 to 8 hours.

The alkali metal ion contained in the ion exchange liquid may be an ion of a metal selected from the group consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs) , A cesium ion or a rubidium ion and a cesium ion, and more preferably a cesium ion.

The zeolite impregnated in the ion exchange liquid may be zeolite A, zeolite X, zeolite Y, zeolite L, ZSM-5, beta-zeolite, ZSM-8, ZSM-11 or mixtures thereof, have.

The zeolite substituted with an alkali metal is obtained by impregnating zeolite with an ion exchange solution containing an alkali metal ion. The zeolite substituted with an alkali metal includes lithium (Li), sodium (Na), potassium (K Zeolite A, zeolite X, zeolite Y, zeolite L, ZSM-5, beta-zeolite, ZSM-8, ZSM-11 or mixtures thereof substituted with at least one selected metal selected from rubidium (Rb) and cesium And may be zeolite Y, which is characteristically substituted with one or more metals selected from rubidium and cesium, and may more particularly be zeolite Y substituted with cesium.

After the ion exchange with the ion exchange liquid is performed, the step of drying the obtained zeolite at a temperature of 100 to 150 ° C in the air for 9 to 24 hours can be further performed.

The lithium metal oxide mixed in the step a) may be a spinel-based lithium manganese metal oxide, and the spinel-based lithium metal oxide may be a material defined by the following formula (1).

(Formula 1)

Li _{1 + x} Mn _2-y M _y O ₄

X is a real number of 0? X? 0.2, y is a real number of 0? Y? 0.7, and M is a divalent or trivalent metal. In detail, in the spinel-based lithium metal oxide according to Formula 1, M, which is a divalent or trivalent metal, is one or more of Mg, Fe, Co, Ni, Cu, Zn, Cd, It may be a metal selected.

The lithium metal oxide to be mixed in the step a) may be in the form of a powder having an average particle size of 1 m to 30 m.

In step a), 0.1 to 10 mol% of zeolite and 99.9 to 90 mol% of lithium metal oxide, specifically 1 to 10 mol of zeolite and 99 to 90 mol% of lithium metal oxide may be mixed. The molar ratio between the lithium metal oxide and the zeolite is a molar ratio that can prevent the deterioration of insertion and desorption of lithium ions in the spinel type lithium metal oxide particles by the zeolite while effectively preventing the deterioration of the spinel type lithium metal oxide particles at high temperatures .

The mixing of the zeolite and the lithium metal oxide in the step a) may be carried out by any method as long as it is a commonly used method for mixing the materials. A specific, non-limiting example is dry or wet ball milling.

In the method of manufacturing a cathode active material for a lithium secondary battery according to an embodiment of the present invention, the heat treatment may be performed at a temperature of 400 to 900 DEG C in the presence of oxygen. The heat treatment atmosphere may be a mixed gas atmosphere or an air atmosphere in which oxygen and an inert gas are mixed. If the heat treatment temperature is less than 400 ° C., there is a danger that the surface of the lithium metal oxide is not sufficiently modified by the zeolite. If the heat treatment temperature is higher than 900 ° C., the heat treatment temperature may be 400 ° C. to 900 ° C., There is a risk that agglomerates (bulk sintered bodies) that are excessively agglomerated by heat treatment are produced.

The heat treatment temperature may be 400 ° C. to 900 ° C., preferably 400 ° C. to 600 ° C., in view of producing the cathode active material with a uniform size particle size and surface-modifying (coating) the lithium metal oxide surface uniformly and uniformly with zeolite.

The method for preparing a cathode active material for a lithium secondary battery according to an embodiment of the present invention may further include a post-treatment step of pulverizing a product containing a lithium metal oxide surface-modified with zeolite obtained by heat treatment.

(Production example)

Preparation of alkali metal substituted zeolite

And an ion exchange solution of distilled water containing 0.5 M concentration of Cs + ions was prepared. The prepared ion-exchange liquid was heated to 50 ° C, 10g of zeolite-Y per 100g of the ion-exchange liquid was added to the warmed ion-exchange liquid, and ion exchange was performed for 6 hours. The ion-exchanged zeolite was dried in an oven at 120 DEG C for 12 hours.

(Example 1)

Lithium manganese nickel complex oxide (LiMn _1.5 Ni _0.5 O ₄ ) and the ion-exchanged zeolite prepared in Production Example were mixed so as to be 99 mol% lithium manganese nickel composite oxide and 1 mol% ion-exchanged zeolite. Thereafter, the cathode active material was heat-treated at 500 ° C for 5 hours in the air to prepare a cathode active material. The cathode active material obtained by the heat treatment was pulverized by induction and used in the manufacture of a lithium secondary battery.

The prepared cathode active material, a binder (Polyvinylidene Fluoride) and a carbon black (super-P) were mixed in a weight ratio of 90 (cathode active material): 5 (binder): 5 (carbon black) To prepare a cathode active material slurry. The prepared positive electrode active material slurry was applied to an aluminum current collector and dried, followed by pressing with a roll press to prepare a positive electrode.

Lithium foil was used as the cathode and polyethylenic microporous membrane was used as the separator. A mixed solution of 1M LiPF ₆ in ethylene carbonate / ethylmethyl carbonate (1 (EC): 2 (EMC) vol / vol) was used as the electrolyte solution.

The electrolytic solution was impregnated into the separator, then placed between the prepared anode and cathode, and then sealed with a case to prepare a coin cell.

(Example 2)

A cathode active material and a lithium secondary battery were prepared in the same manner as in Example 1, except that 2 mol% of alkali metal-substituted zeolite and 98 mol% of lithium manganese nickel composite oxide were mixed in Example 1.

(Example 3)

A cathode active material and a lithium secondary battery were prepared in the same manner as in Example 1 except that 5 mol% of alkali metal substituted zeolite and 95 mol% of lithium manganese nickel composite oxide were mixed in Example 1.

(Comparative Example)

A cathode active material and a lithium secondary battery were prepared in the same manner as in Example 1, except that only the pure lithium manganese nickel complex oxide was used without mixing the alkali metal-substituted zeolite in Example 1.

FIG. 1 is a graph showing X-ray diffraction results of the cathode active material prepared in Example 1, FIG. 2 is a graph showing X-ray diffraction results of the cathode active material prepared in Example 2, and FIG. Ray diffraction results of the cathode active material prepared in Example 3, and FIG. 4 is a view showing X-ray diffraction results of the cathode active material prepared in Comparative Example. Here, the X-ray diffraction was measured using Cu K? Of 40 kV, 40 mA, and the result of 2? In the range of 10? 90? At? -2 ?.

As can be seen from FIGS. 1 to 3 and FIG. 4, it was confirmed that both of the prepared cathode active materials had lithium manganese nickel composite oxide on spinel.

FIG. 5 is a scanning electron microscope (SEM) image of the cathode active material prepared in Example 1, FIG. 6 is a scanning electron microscope (SEM) image of the cathode active material prepared in Example 2, FIG. 8 is a scanning electron microscope (SEM) image of the cathode active material prepared in Comparative Example. FIG.

5 to 7, it can be seen that as the amount of zeolite added increases, the particle growth of the lithium manganese nickel complex oxide is inhibited, resulting in a decrease in the overall particle size. In addition, It can be seen that there is a bimodal distribution in which small particles coexist.

As shown in FIG. 8, when a cathode active material is formed of a pure lithium manganese nickel composite oxide, active material particles having a relatively large particle size and a uniform distribution are produced.

In order to test the high temperature charging and discharging characteristics of the lithium secondary batteries manufactured in Examples 1 to 3 and Comparative Examples, repetitive charging and discharging was performed at a temperature of 55 캜. The first and second charge / discharge cycles were initially charged / discharged at 0.1 C for stabilization of the electrode. After that, charge / discharge was performed at 0.2 C for the third cycle. The charge / discharge was performed 80 times under the condition of 0.5C. Charging was performed with a 4.5V constant current / constant voltage method.

As can be seen from Table 1, in the case of the cathode active material prepared in the examples, the discharge capacity as compared with the pure lithium manganese nickel composite oxide of the comparative example is as shown in Table 1 below. It can be confirmed that it is remarkably increased.

(Table 1)

FIG. 9 shows the discharge capacity per cycle at the time of performing 80 charge / discharge cycles at 55 ° C. The results of the measurement of the lithium secondary battery manufactured in Example 2 (red color) and the lithium secondary battery produced in Comparative Example The measurement results (black city) are shown together.

As can be seen from FIG. 9, the cathode active material according to the present invention has a higher discharge capacity, and is excellent in high-temperature stability and improved reversibility.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Those skilled in the art will recognize that many modifications and variations are possible in light of the above teachings.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (10)

A cathode active material for a lithium secondary battery comprising a spinel-type lithium metal oxide according to Chemical Formula 1, which is surface-modified with zeolite Y substituted with cesium (Cs) and 12-membered oxygen ring.
(Formula 1)
Li _{1 + x} Mn _2-y M _y O ₄
(Wherein x is a real number of 0? X? 0.2, y is a real number of 0? Y? 0.7, and M is a divalent or trivalent metal) delete delete The method according to claim 1,
Wherein the positive electrode active material comprises 0.1 to 10 mol% of zeolite Y and 99.9 to 90 mol% of lithium metal oxide. delete A lithium secondary battery containing the cathode active material for a lithium secondary battery according to claim 1 or claim 4. a) mixing a 12-membered oxygen ring zeolite Y substituted with cesium (Cs) and 12 oxygen atoms in ring form with a spinel-type lithium metal oxide according to formula 1; And
b) subjecting the mixture of step a) to heat treatment to produce a spinel-type lithium metal oxide surface-modified with zeolite Y substituted with cesium (Cs);
Wherein the positive electrode active material is a positive electrode active material.
(Formula 1)
Li _{1 + x} Mn _2-y M _y O ₄
(Wherein x is a real number of 0? X? 0.2, y is a real number of 0? Y? 0.7, and M is a divalent or trivalent metal) 8. The method of claim 7,
In the step a), 0.1 to 10 mol% of zeolite Y and 99.9 to 90 mol% of lithium metal oxide are mixed. 8. The method of claim 7,
Wherein the heat treatment is performed at a temperature of 400 to 900 占 폚 in the presence of oxygen. 8. The method of claim 7,
The above-
a) before the step,
1 to 80 parts by weight of zeolite Y is impregnated into the ion exchange solution containing 0.01 to 2 M cesium (Cs) ions and heated to 30 to 80 캜 based on 100 parts by weight of the ion exchange solution for 4 to 8 hours to obtain cesium ), ≪ / RTI >
Wherein the positive electrode active material is a lithium salt.

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