WO2014157744A1

WO2014157744A1 - Cathode active material for lithium secondary battery, method for producing same, and lithium secondary battery comprising same

Info

Publication number: WO2014157744A1
Application number: PCT/KR2013/002505
Authority: WO
Inventors: 최수안; 김세환; 이승원; 홍진곤; 김다영; 정봉준
Original assignee: 주식회사 엘앤에프신소재
Priority date: 2013-03-26
Filing date: 2013-03-26
Publication date: 2014-10-02

Abstract

The present invention relates to a cathode active material for a lithium secondary battery, a method for producing same, and a lithium secondary battery comprising same and can provide a cathode active material for a lithium secondary battery, the cathode active material comprising: a compound capable of reversible lithium intercalation and deintercalation; and a complex coating layer comprising M formed on the surface of the compound, wherein said M is at least one metal selected from the group consisting of Al, Zr, Ti, Mg, V, Zn, Mo, Ni, Co, and Mn and the surface free energy of the cathode active material is 4 to 20% lower than that of the compound capable of reversible lithium intercalation and deintercalation.

Description

【Specification】

[Name of invention Γ

Cathode active material for a realm secondary battery. Method for manufacturing the same and Li ′ f secondary battery comprising the same

Technical Field

It relates to a method for producing a cathode active material for a lithium secondary battery and a cathode active material for a lithium secondary battery. _.

Background Art

Recently, increasing the need for high performance and high capacity of a battery used as a power source for portable electronic ^"in relation to the miniaturization and weight reduction trend in the group yidol device. Cell generates electric power by using a material capable of electrochemical banung to the positive and negative electrodes A typical example of such a battery is a lithium secondary battery that generates electrical energy by a change in chemical potential when lithium ions are intercalated / deintercalated at a positive electrode and a negative electrode.

The lithium secondary battery is a lithium ion _. Reversible intercalation / deintercalation is possible using positive and negative active materials. It is prepared by filling an organic electrolyte or a polymer electrolyte between the anode and the cathode. As a positive electrode active material of a lithium secondary battery, a lithium composite metal is used _. Compound is being used. Examples are LiCo¾, LiMn ₂ 0 ₄ , LiNi0 ₂ . Composite metal oxides such as LiMn0 ₂ Is being studied.

Mil-based positive electrode active materials such as LiMn ₂ O ₄ and LiMn0 ₂ in the positive electrode active material are easy to synthesize. It is relatively inexpensive, has the best thermal stability compared to other active materials at the time of overcharging, and has the disadvantage of low capacity, although it is an attractive material due to its low pollution to the environment _.

LiCo0 ₂ has good electrical conductivity and high battery voltage of about 3.7V, cycle life characteristics. Since stability and discharge capacity are also excellent, it is a representative cathode active material that is currently commercialized and commercially available. However, LiCo0 ₂ has a problem in that its price competitiveness is low since it occupies more than 30% of the battery price because of high price. .

In addition, LiN) ₂ exhibits the battery characteristics of the highest discharge capacity among the cathode active materials mentioned above _, but has disadvantages that are difficult to synthesize. In addition, the high oxidation state of nickel is the source of ^'battery and decrease electrode life. Self-discharge is severe and there is a problem of inferior reversibility. Arler. Insufficient stability-We are having difficulty in commercialization. .

According to KR1999-0071411 to improve the safety and life of the battery _. After the surface of the positive electrode active material was coated with Γ metal alkoxide and sol in crystalline or semi-crystalline state. It has been disclosed to provide a positive electrode active material in the form of a surface treated with a metal oxide by heat treatment, and according to KR 2002—0029218, a metal oxide coating has been reported for the purpose of improving high rate characteristics and battery life. [Content of invention]

[Problem to solve]

The present invention provides a cathode active material for a lithium secondary battery having excellent high-yield lifespan characteristics. It is to provide a lithium secondary electron-containing a positive electrode containing the positive electrode active material.

[Measures of problem]

Seen. In one embodiment of the invention. Compounds capable of reversible intercalation and deintercalation of lithium; And a composite coating layer comprising M formed on the surface of the compound; to be a cathode active material for a lithium secondary battery. M is Al. Zr. Ti. Mg, Ca. V. Zn. Mo, Ni. Consisting of Co and Mn. At least one metal selected from the group, the surface free energy of the positive electrode active material is 4 to 20% less than the surface free energy of the reversible intercalation and de-intercalation of the compound capable of lithium secondary battery Can be provided.

M may be A1 _. . . ^The compound capable of reversible intercalation and deintercalation of lithium may be a lithium cobalt complex oxide. ^{: '}

The cathode ¾ material may have a polarity of 5 to 30 mN / m as a component of surface energy.

The increase ratio of M of the coating layer to the total weight of the positive electrode active material is 0.02 To 0.2. .

The form of the coating layer may be in the form of island.

In another embodiment of the present invention, a compound capable of reversible intercalation and deintercalation of lithium; Preparing a compound powder comprising M 5: in a compound capable of reversible intercalation and deintercalation of lithium: comprising M. By dry mixing of the compound powder, subjecting the powder compound containing M in the reversible intercalation and the surface of the possible intercalation compound of the ^lithium, uniformly attached; And a compound powder comprising M. Compounds capable of reversible intercalation and deintercalation of lithium were heat-treated to temperatures above 400 ^° C and below 800 ^° C. A compound capable of reversible intercalation and deintercalation of lithium coated with a composite cotang layer comprising M; Obtaining; comprising ^' . M is A1. Zr. Ti, Mg, Ca. V, Zn. Mo. Ni. It may provide at least one of metal, like a secondary battery, the positive electrode rirom hwalmuljilwa method selected from the group consisting of Co and Mn .5 ^'. The firing temperature of the step of firing the prepared mixture is above 400 ^° C. and

It may be up to 600 ^° C. .

M may be A1.

The surface free energy of the prepared cathode active material for a lithium secondary battery may be 4 to 20% less than the surface free energy of a compound capable of reversible intercalation and deintercalation of lithium. The prepared cathode active material may have a degree of physical property of 5 to 30 iiiN / m, which is a component of surface energy.

^"The prepared positive electrode active material may be a degree of dispersion of component of surface energy of 30 to 50 ριΝ / ηι.

The weight ratio of M of the coating layer to the total amount of the prepared positive electrode active material is

0.02 to ^' 0.2. . . _. ,; - In another embodiment of the present _invention, a positive electrode comprising a cathode active material for a lithium secondary battery according to one embodiment of the invention described above: a negative electrode including a negative electrode active quality; And an electrolyte: is provided.

【Effects of the Invention】

It is to provide a cathode active material having improved ratio of the conventional oxide-coated cathode active material to ^' high ratio. 【Brief Description of Drawings】 _.

1 is a schematic view of a lithium secondary battery.

[Specific plan contents to carry out invention]

Below. Embodiments of the present invention will be described in detail. However, the present invention is presented by way of example and the present invention is not limited thereto. It is only defined by the scope of the claims. In one embodiment of the invention there is provided a reversible intercalation and deintercalation ⁰ lithium capable compound of lithium; And a port formed in the surface M of the ^compound, hereinafter 5 composite coating layer; back and comprises a cathode active material for a lithium secondary battery, ^"wherein M is _Al. , Zr.

Ti, Mg, Ca. V, Zn. At least one metal selected from the group consisting of Mo, ^ Ni, Co and Mn. The surface free energy of the cathode active material provides a cathode active material for a lithium secondary battery that is 4 to 20% less than the surface free energy of a compound capable of reversible intercalation and deintercalation of lithium.

The positive electrode active material including the coating layer was able to improve the battery characteristics of the lithium secondary battery. Conventional anode. Article coated with a metal oxide to the active material surface as the invention described. Unlike the the embodiment of the ^invention, the lithium having the improved cities and long-life characteristics by controlling the surface energy of the positive electrode active material can be prepared a rechargeable battery. More specifically. M may be A1.

Than 5. Specifically. Above _. The compound capable of reversible intercalation and deintercalation of lithium may be a lithium cobalt-based composite oxide. However, it is not limited thereto.

The positive electrode active material having the coating layer has a lower energy level than the positive electrode active material not including the surface energy group-coating charge, thereby suppressing excessive wet ting of the electrolyte on the surface, and thus including a conventional coating layer. Deterioration due to a charge and discharge cycle (particularly, a charge and discharge cycle with high rate discharge) can be reduced. .

In addition, the positive electrode active material including the coating layer has a polarity (y—P) of 5-30 mN / m lower than that of the positive electrode active material including the conventional coating layer. ^'

Due to such low polarity, the surface energy is reduced to prevent excessive wet ting of the electrolyte on the surface of the cathode active material, thereby suppressing side reactions by the electrolyte. Excellent life characteristics by suppressing the increase in battery resistance ^. It provides a positive electrode active material.

According to one embodiment of the present invention comprising a coating dance _. The positive electrode active material has a lower polarity than the positive electrode active material including a conventional coating filler, and thus, the electrical properties may be improved due to the favorable reaction caused by the electrolyte than the positive electrode active material having a high polarity. The dispersity (y—D), which is another component constituting the surface energy of the positive electrode active material including the coating layer, affects fluidity between particles in the positive electrode active material. The degree of cohesion may be lowered, thereby reducing the phenomenon of slurry gelation and electrode thickness unevenness in the electrode process, which may be related to electrode processability. . , The weight ratio of the coating layer M on the total weight of the ^"positive electrode active material may be 0.02 to 0.2 days. M of when the increase ratio is less than 0.02 _. Role (electrolytic solution or _{decomposition.} The crystal structure stability ^"Chemistry of the positive electrode active material surface electrode) can not be expected can receive the reduction of the initial capacity is decreased, and charge and discharge efficiency when greater than 0.2.

The type of the coating layer is a single or multiple layers or islands It may be in the form. If the layer forms, due to the uniform coating as above - can expect such advantages, and if ⁱ on the island shape by banung the specific active site and ⁱ selectively on the active material surface while the effect of the side reaction control appear larger thermal along with improvements in battery characteristics The effect of improving stability can be expected.

. Of the present invention _. In another embodiment. Preparing a compound capable of reversible intercalation and deintercalation of lithium; Preparing a compound powder comprising M; Dry mixing a compound powder containing M with the compound capable of reversible intercalation and deintercalation of the lithium. Step for uniformly attaching the reversible intercalation and eudi intercalation capable hwahapmulwa of the lithium _on the surface including the M hanon compound powder; And a compound capable of reversible intercalation and deintercalation of lithium to which the compound powder comprising M is attached at 400 ^° C. And heat-treating at a temperature above 800 "C to obtain a compound capable of reversible intercalation and deintercalation of lithium coated on the surface of the composite coating comprising M. It is at least one metal selected from the group consisting of A1, Zr.Ti.Mg.Ca.V, Zn.Mo.Ni, Co and Mn.

When firing together the compound containing M for the coating layer including M of the compound and the positive electrode active material, silver for effective firing may be higher than 400 ^° C and 800 ^° C.

. . . . 8 ^'■ . For example, when fired at temperatures below 400 ° C ^' , the coating material and the anode active _. Due to the lack of reaction between materials, it is difficult to expect the effect of coatings such as ^' Yura C ^' ). In addition, when fired at a temperature above 80 CTC, M is excessively doped and the initial stage of the battery. Along with the decrease in capacity, deterioration of life characteristics at room temperature, high temperature and low temperature may occur. - ^'

For the coated bicarbonate active material _. Since the description is the same as the embodiment of the present invention described above, it will be omitted. In another embodiment of the present invention. anode. Lithium secondary comprising a negative electrode and an electrolyte _. I'm former. The positive electrode comprises a current collector and a positive electrode active material layer formed on the current collector. The positive electrode active material layer is. Lithium. Secondary residue that includes the positive electrode active material described above. ^'

Descriptions related to the cathode active material are omitted because they are the same as in the above-described embodiment of the present invention.

The positive electrode active material layer may include a binder and a conductive material.

The binder adheres the positive electrode active material particles to each other well. It also serves to adhere the positive electrode active material to the current collector. Polyvinyl alcohol is a representative example. Carboxymethyl Cell Rose, Hydroxypropyl Seal Rose, Diacetyl Cellulose. Polyvinylchloride, carboxylated polyvinylchloride, polymers comprising polyvinylfluoride ᅳ ethylene oxide, polyvinylpyrrolidone, polyurethane ᅳ polytetraflu Oroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber ,. Acrylated styrene—butadiene rubber. Epoxy resin. _. Nylon may be used. It is not limited to this /

The conductive material is used to impart conductivity to the electrode, which is composed of a battery. If any one electronically conductive material without causing chemical changes ^■ also possible to use, and examples thereof include natural hokyeon. Artificial Graphite ᅳ Carbon Black, Acetylene Black _. . Kechenbleck. Carbon-based materials such as carbon fibers; Metal materials such as metal powder or metal fibers such as copper, nickel, aluminium and silver; conductive polymers such as polyphenylene derivatives; Or an electroconductive material containing these mixture can be used. ^"

The negative electrode is a current collector _. And a negative electrode formed on the current collector; It includes an active material layer. The negative electrode active material layer includes a negative electrode active material. . ^'

A material capable of reversibly intercalating / deintercalating lithium silver as the negative electrode active material. Lithium metal. Alloy of lithium metal. ^' Materials capable of doping and undoping lithium, or transition metal oxides. ^'

Water capable of reversibly intercalating / deintercalating the lithium ions

/ As a carbon material. Any carbon-based negative electrode active material commonly used in lithium ion secondary batteries may be used. Examples thereof include crystalline carbon. Amorphous carbons or these may be used together-examples of such crystalline carbons are amorphous. Plate. Flakes. Graphite such as spherical or fibrous natural ambly ^' or artificial humps. Examples of the amorphous carbon include soft carbon (low carbon). . On firing carbon) or hard carbon (hard carbon), there may be mentioned mesophase pitch carbide, fired coke, and so on. ^{^ '-}

Examples of the lithium metal alloy include lithium and Na _. . K, Rb, Cs, Fr, Be / Mg, Ca, Sr, Si, Sb, Pb ᅳ In, Zn, Ba, Ra. Alloys of metals selected from the group consisting of Ge, Al and Sn can be used. Of

^y ] materials capable of doping and undoping lithium include Si, sio _x (o <x <2),

Si-Y alloy (wherein Y is selected from the group consisting of alkali metal, alkaline earth metal, group 13 element, group 14 element ᅳ transition gold. Rare earth element and combinations thereof, not Si). Sn. ^' Sn0 ₂ . Sn- Y (wherein Y is an alkali metal alkaline earth _metal. 13 element. 14 elements, transition metals and rare earth elements. Being selected from the group consisting of elemental ^ a. Sn is not) and the like It is also possible to use a mixture of at least one of these and Si¾. As the additive element Y, Mg. Ca. Sr, Ba. Ra. Sc. Y. Ti. Zr, Hf. Rf. V. Nb, Ta. Db. Cr, Mo. W, Sg. Tc. Re, Bh, Fe. Pb, Ru, 0s, Hs, Rh, Ir. Pd, Pt. Cu. Ag. Au, Zn. CD. B. Al, Ga. Sn. In. Ti, Ge. P. As, Sb 'Bi, S. Se, Te, Po, and combinations thereof. _. To ^"the jeonah metal oxide and the like can be mentioned vanadium oxide, lithium vanadium oxide. -

. The negative electrode active material layer also includes a binder. Optionally, more conductive materials may be included. .

The binder makes the negative electrode active material particles well together _. Attaching and cathodic bow It attaches the material well to the current collector. Representative examples thereof include polyvinyl alcohol. Carboxymethylcellrose. Hydroxypropylcellulose. Polyvinylchloride. Carboxylated polyvinylchloride. Polyvinylfluoride ... Polymers containing ethylene oxide—polyvinylpyrrolidone, polyurethane, polytetrafluorotoethylene, polyvinylidene fluoride, ^' polyethylene, polypropylene, styrene—butadiene rubber, acrolle Yated styrene-butadiene rubber. Epoxy resin, nylon, etc. can be used. It is not limited to this.

The conductive material is ^. In a battery which is used to impart conductivity to an electrode, it is configured. Any electronically conductive material can be used without causing chemical changes, e.g. natural smoke. Artificial graphite. Carbon black. Acetylene black. Carbon-based materials such as ketjenblack carbon fiber; Copper. Nickel, aluminum. Metal powders such as silver, metal oils and the like, and metal-based materials; conductive polymers such as polyphenylene derivatives; Or a conductive material containing these ^' combinations.

The current collector is copper foil. Nickel foil Stainless steel foil, titanium foil. Nickel foam, copper foam. A polymer substrate coated with a conductive metal, and a combination thereof may be used.

It is ^not: The current collector may be used in the A1, but is not limited thereto. The negative electrode and the positive electrode are mixed with an active material, a conductive material and a binder in a solvent to prepare an active material composition. This composition is prepared by applying to a current collector. Since such an electrode manufacturing method is well known in the art, in the present specification Detailed description will be omitted. The solvent may be N-methylpyridone or the like, but is not limited thereto.

^_'. The electrolyte contains a non-aqueous organic solvent and a lithium salt.

The non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the cell can move.

The _{non-aqueous-organic} solvent is a carbonate-based. Ester system. Ether type. Ketone based, alcohol based, or aprotic ^' solvents may be used. Examples of the carbonate solvent include dimethyl carbonate (DMC). Diethyl carbonate (DEC), dipropyl carbonate (DPC). Methylpropyl carbonate (MPC). Ethyl Pro ^Phil carbonate (EPC). Methylethyl carbonate (MEC). Ethylene carbonate (EC), propylene carbonate (PC). Butylene carbonate (BC) and the like can be used. The ester solvent is methyl acetate. ^, Ethyl acetate, η- propyl acetate, dimethyl acetate eu. ^, Methyl propionate, ethyl propionate, lactones in Υ- butynyl, big surprise Id (decanolide), valerolactone, methoxy feet no lactone (iiieval ono lac tone), rakron (€ 3 () 13 01) caprolactam, And the like can be used. The ether solvent is dibutyl ether, tetraglyme. Diglyme. Dimethoxyethane, 2-methyltetrahydrofuran. Tetrahydrofuran and the like can be used. As the ketone solvent, cyclonucleanone may be used. In addition, ethyl alcohol, isopropyl alcohol, etc. may be used as the alcohol solvent, and as the aprotic solvent, R-CN (R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms). Nitrile dimethyl foam, such as a double bond aromatic ring or an ^' ether bond) Amides, such as 1 eu name amide, ^3: dioxide dioxide, such as sulfonic acids solran solran there is used ^", such as sulfolane (sulfolane) acids.

-. The non-aqueous organic solvent may be used alone or in combination of one or more, and the mixing ratio in the case of using a mixture of one or more subphases is 5 to the desired battery performance. Depending flew to properly adjusted, it can be well understood by those who engage in art ^'field. ——. ^''

.Also. In the case of the carbonate solvent, it is preferable to use a mixture of a cyclic carbonate and a chain ^' carbonate. In this case, the cyclic carbonate and the chain carbonate may be mixed and used in a volume ratio of 1: 1 to 1: 9, so that the performance of the electrolyte 0 may be excellent.

The non-aqueous' organic solvent according to the embodiment of the present invention may further include an aromatic hydrocarbon organic solvent in the carbonate solvent. In this case, the _carbonaceous solvent and the aromatic _ᅵ hydrocarbon-based organic solvent may be mixed in a volume ratio of 1: 1 to 30: 1. ^. ： _. -'

5. As the aromatic hydrocarbon-based organic solvent may be used an aromatic hydrocarbon compound of the formula (1).

Chemistry: Formula 1]

1ί

Λ (In Formula 1, to ¾ are each independently hydrogen, -halogen, C1 to C10 alkyl group, haloalkyl group or a combination thereof.)

The aromatic hydrocarbon organic solvent may be benzene, fluorobenzene, 1.2-difluoro benzene, 1,3-difluorobenzene, 1,4-difluorobenzene. 1,2,3—trifluorobenzene, 1.2, 4-trifluorobenzene. Chlorobenzene, 1.2-dichlorobenzene. ^, 1,3-dichlorobenzene. 1,4'dichlorobenzene, 1,2,3'trichlorobenzene, 1.2.4-trichlorobenzene, iodobenzene, ᅳ 1,2-dioodobenene, 1.3—diodobenzene. 1.4-Diiodobenzene. 1.2,3—triiodobenzene, 1.2.4-triiodobenzene. Toluluen./Pluoruluen. 1.2—difluorotle-luene. 1.3 ᅳ difuluroluene. 1.4—difluoroluene ᅳ 1.2.3—trifluoroluene ᅳ 1.2,4—trifluoroluene. Chloroluene, 1.2-dichloroluene. Luene 1.3-dichloro. 1.4-dichloroluene. 1.2,3-trichloroluene. 1.2, 4-trichloroluene. Iodine toluene ᅳ 1,2-Diiodo toluene .. 1,3-Diaodo toluene ᅳ 1,4-Diaodo toluene. 1.2.3-triiodoru.en. 1.2.4-triiodoluene. Xylenes and combinations thereof. The non-aqueous electrolyte may further include vinylene carbonate or an ethylene carbonate compound represented by the following Chemical Formula 2 to improve battery life.

In Formula 2, R ₇ and R ₈ are each independently hydrogen, a halogen group, a cyano group (CN), a nitro group (N0 ₂ ), or a C1 to C5 fluoroalkyl group, and R ₇ and R ₈ least one of the enemy ^'is a halogen group, a cyano group (CN), nitro (N02) or a C1 to C5 alkyl group in the _{fluoroalkyl),:.,,.} Representative examples of the ethylene ^' carbonate-based compound is difluoro ethylene carbonate, chloroethylene carbonate ᅳ dichloroethylene carbonate / bromoethyl styrene carbonate. Dibromoethylene carbonate, nitroethylene carbonate, cyano ethylene carbonate, fluoroethylene carbonate, etc. are mentioned. In the case of further use of such a life improving additive, the amount thereof can be properly adjusted. The lithium salt ^air, are dissolved in an organic solvent. Acts as a source lead of the lithium ions in the battery enables the ^operation, the basic lithium secondary battery, and a material which serves to facilitate the movement of lithium ions between the positive electrode and the negative electrode eu such lithium salt Representative examples include LiPF ₆ , LiBF ₄ . LiSbF ₆ . LiAsF ₆ , LiC ₄ F ₉ S0 ₃ . LiC10 ₄ . LiA10 ₂ . LiAlCl ₄ , LiN (C _x F _{2x + 1} S0 ₂ KC _y F _{2y + 1} S0 ₂ ), where. X and y are natural numbers) LiCl, Lil and LiB (C ₂ 0 ₄ ) ₂ (lithium bisoxalato One or two subphases selected from the group consisting of lithium bis (oxalato borate: Li BOB) are included as supporting electrolytic salts. ^” The concentration of lithium salt is preferably used within the range of 0.1 to 2.0M. When the concentration of the lithium salt is included in the above range, since the electrolyte has an appropriate conductivity and viscosity, it can exhibit excellent electrolyte performance and can effectively move lithium. Depending on the type of lithium secondary battery, between the positive and negative electrodes _. Separator may be present. These ^separators, polyethylene. Polypropylene. Polyvinylidene

May be ^used, the fluoride or yideulwa multilayer film having two or more ^_layers'. It is a matter of course that a mixed multilayer film such as polyethylene / polypropylene two-layer separator, polyethylene / polypropylene / pol 5ethylene ^' 5 three-layer _, separator, polypropylene / polyethylene / polypropylene, three-layer separator and the like can be used.

Lithium secondary batteries are lithium-ion 'batteries, depending on the type of separator and electrolyte used. Can be classified into lithium ion polymer battery and lithium polymer battery, and according to the shape of cylindrical. Square shape. ^■ coin type. It can be classified into pouch type. Depending on the size, it can be divided into 10 bulk type and thin film type. The structure and manufacturing method of these batteries are widely used in this field _. Since it is known, the detailed description is omitted. 1 shows a lithium secondary battery of the present invention _. A representative structure is shown schematically. That "as the lithium secondary battery 1 shown in Figure 1 is present between the anode 3, cathode 2 and the anode 3 and ^the" negative electrode (2). 15 electrolytic solution impregnated in the separator 4 And a battery container 5 comprising a. And a sealing member 6 for sealing the battery container 5.

. Hereinafter, examples and comparative examples of the present invention are described. Such following examples are only one shishishi of the present invention, and the present invention is not limited to the following examples. 0 Example Example 1

Co ₃ 0 ₄ on the mixer. And Li ₂ C0 ₃ 1: 1.040. It was put in a molar ratio of (Co ₃ O ₄ : Li ₂ C0 ₃ ) and mixed.

The mixed powder was heat-treated at 1000 ^° C. for 8 hours to prepare a lithium-cobalt composite oxide.

The lithium cobalt composite oxide and A1 (0H) _.3 powder were dry mixed at a weight ratio of 100: 0.2 (lithium cobalt composite oxide: AΚ0Η) 3) to uniformly mix the A1 (0Η) ₃ powder on the surface of the lithium cobalt composite oxide particles. Attached.

^■ the lithium cobalt oxide particles surface Α1 (0Η) a to uniformly attach the _third powder ^"eu NOBILTA was heunhap precision using (Hosokawa Micron Groupft) eu N0BILTA A1 (0H) using a high shear equipment to ₃ powder Evenly attached. ᅵ

The dry mixed powder was heat-treated at 600 ^° C. for 5 hours to prepare a cathode active material. ^' Example 2

A lithium ion positive active material was prepared in the same manner, except that the dry mixed powder prepared in Example 1 was heat-treated at 500 t for 5 hours. Comparative Example 1 Co ₃ O ₄ and Li ₂ CO ₃ were added to the mixer in a molar ratio of 1: 1.040 (Co ₃ 0 ₄ : Li ₂ CO ₃ ) and mixed. 8 hours at 1000 ^° C mixed powder. Heat treatment to prepare a positive electrode active material. Comparative Example 2

A positive electrode active material was prepared in the same manner, except that the dry mixed powder prepared in Example 1 was heat-treated at 400 ^° C. for 5 hours. _. Comparative Example 3 ^'

A1—.4635 g of isopropoxide to ethane. After dissolving in lOiiil, a mixed solution was prepared using a mixer. The mixed solution was stirred at 100 g of the positive electrode active material of Comparative Example ^' 1.

The positive electrode active material was then low tapped in so r.

The dried powder was heat-treated at 600 ^° C. for 5 h to prepare a positive electrode active material coated with a wet M oxide. Comparative Example 4 An active material was prepared in the same manner, except that the dried powder prepared in Comparative Example 3 was heat-treated at 500 C for 5 hours. Experimental Example 1 Surface Free Energy Measurement

Surface free energy of the positive electrode active material prepared in Examples 1 to 2 and Comparative Examples 1 to 4 _; The measurement was performed _. The measurement was performed using KRUSS DSA100 and K100 instruments. The measurement was measured by the Contact Angle Method.

-Surface free energy measurement result

Table 1 shows the evaluation results measured in the experimental example.

TABLE 1

Table 1 shows the surface free energy of the positive electrode active material according to Example 1 to magnetic field 2 and Comparative Examples 1 to 4. It can be seen that the surface free energy of Examples 1 and 2 of the present application is lower than that of the comparative example without forming the coating layer. This—the coating method is different _. The surface free energy of Comparative Examples 3 to 4 is higher than that of Comparative Example 1, showing the difference between the results. See Examples 1 and 2 and Comparative Example 2. With decreasing firing temperature

Surface free energy ⁷ , increase. Increasing the dispersion of one of the components of surface free energy and energy

You can check. Therefore, Comparative Example 2. The firing temperature of the coating was

'' The lower the dispersion, the higher the dispersion.

There are disadvantages that are hard to implement. In addition, Comparative Example 3, which is a conventional coating method, does not form an A1 coating layer, and Comparative Example 1 does not have a difference in surface free energy.

There is no change in dispersion and polarity. Characteristics by Dispersion and Polarity

. Difficult to implement 、 '·

-

-Table 1 shows the Co elution amount. Co dissolution was measured using 5 ml of EC: EMC = 1: 1 LiPF ₆ 1M at 60 ° C in Aubon at 30 rpm with the positive electrode active material lg of one example.

The measurement was left for 14 days with stirring. As you can see in Table 1 above.

Nose with reduced surface free energy of the embodiment. Cathode forms positive electrode active material in electrolyte

It can be confirmed that Co dissolution is reduced by suppressing excessive wetting on the surface.

It is confirmed that Examples 1 to 2 have a greater reduction in elution amount than Comparative Examples 3 to 4.

can do. Production of coin cell

95 wt ¾ of the positive electrode active material prepared in Examples 1 and 2 and Comparative Examples 1 to 4, 2.5% by weight carbon black as a conductive agent. A positive electrode slurry was prepared by adding 2.5 wt% PVDF as a binder to 5.0 wt% N-methyl-2 pyridone (NMP) as a solvent (solvent). The positive electrode slurry has a thickness of 20 to. A positive electrode was prepared by coating, vacuum drying, and rolling press on a thin film of aluminum (A1), which is a ⁴⁰ m positive electrode current collector.

Li-metal was used as the negative electrode.

. In the counter electrode for the positive electrode and the metal Li- prepared as electrolyte ^"is a _{1.15M LiPF 6 EC: DMC (l} :. Using lvol« prepare a coin cell-type half cell in Experimental Example 2: Characterization of cell

^"Below. Table 2 Example 1 ^'is a comparative example 1 and 2 the initial Formation, rate characteristic and cycle 1, 30cycle, 50cycle capacity and the life characteristic of data.

TABLE 2

As can be seen in Table 2 above. Example 1 and Comparative Example 3 exhibited excellent battery properties compared to Comparative Example 1, in which the coating layer was not formed by the coating of Μ (for example, A1) on the surface of the positive electrode active material.一

In the case of Example 1, the discharge capacity, rate characteristics and Good results were obtained in the service life characteristics. Especially. Longer life results have been identified. The invention is ahniri "can be made in many different forms and conventional in the art to be limited to the above embodiments - not change the person with knowledge spirit or essential characteristics of the present ^{_invention.".} It is to be understood that the embodiments described above are illustrative in all respects and not restrictive, in that they may be embodied in other specific forms.

Claims

Patent Claim

[Claim 1]

Compounds capable of reversible intercalation and deintercalation of lithium; And a composite coating layer comprising M formed on the surface of the compound. . Being a positive electrode active material for a lithium secondary battery, including 5.

- _. M is Al, Zr, Ti, Mg. Ca, V. Zn. Mo. Ni. Co and Mn

^• is at least one metal selected from the group. ,

The surface free energy ^"of the positive electrode active ^material, is of the reversible lithium

^' Cathode active material for lithium secondary battery, which is 4 10 to 20% less than the surface free energy of the compound capable of intercalation and deintercalation.

[Claim 2]

_. The method of claim 1.

Wherein M is A1 positive electrode active material for lithium secondary batteries.

15 ^'

[Claim 3]

-According to claim 1,

. The compound capable of reversible intercalation and multiintercalation of lithium is a lithium cobalt composite oxide positive electrode active material for a lithium secondary battery.

20. [Claim 4] ^"

The method of claim 1.

The cathode active material is a cathode active material for a lithium secondary battery having a polarity of 5 to 30 mN / m as a component of the surface energy.

[5.] ^"

The method of claim 1. ^' -The weight ratio of M of the coating layer to the total amount of the positive electrode active material is a lithium secondary battery positive electrode active material is ¾ of 0.02 to 0.2.

Γclaim 6

The method of claim 1,

The coating layer has a form of an island (Island) form a cathode active material for a lithium secondary battery. ^'' . [Claim 7]

Preparing a compound capable of reversible intercalation and deintercalation of lithium;

Preparing a compound powder comprising M;

Reversible intercalation and deintercalation of the lithium Dry mixing the compound powder containing l. Uniformly attaching a compound powder containing M to the surface and a compound capable of reversible intercalation and deintercalation of the .lithium; And

The reversible intercalation and deintercalation of a compound having a compound powder comprising M is heat-treated at a temperature of more than 400 ^° C. and less than 800 ^° C., whereby a composite coating layer comprising M is provided. on the surface ^"¾ reversible intercalation of lithium coated and de-intercalation the compound; to obtain a;..... comprises a, wherein M is Ti g Zr Al, Ca V. Ζη Mo. Ni A method for producing a positive electrode active material for a lithium secondary battery, which is at least one metal selected from the group consisting of Co and Mn.

[Claim port] 8

The method of claim 7.

The firing temperature of the step of firing the prepared mixture is _. Method for producing a positive electrode active material for lithium secondary battery that is more than 400 ^° C and less than 00 ^° C.

[9.] ^"

The method of claim 7 wherein

M is a method of producing a positive electrode active material for lithium secondary batteries. [Claim 10]

The method of claim 7. _.

The surface free energy of the prepared positive electrode active material for lim secondary battery is 4 to 20% less than the surface free energy of the compound capable of reversible intercalation and deintercalation of the lithium secondary battery.

[Claim 11]

The method of claim 7.

The prepared cathode active material has a polarity of 5 to 30 mN / m as a component of the surface energy manufacturing method of the cathode active material for a la top secondary battery.

[Claim 12]

8. The method of claim 7,

The prepared cathode active material has a dispersion of 30 to 50 mN / m, which is a component of surface energy. The manufacturing method of the positive electrode active material for lithium secondary batteries.

[Claims.13]

_. The method of claim 7. .

Method for producing a positive electrode active material for a lithium secondary battery that the weight ratio of M of the coating charge to the total weight of the prepared positive electrode active material is 0.02 to 0.2. , -Claim 14

A positive electrode comprising the positive electrode active material for a lithium secondary battery according to any one of claims 1 to 6;

A negative electrode including a negative electrode active material; And. ^'

Electrolyte; .

Lithium secondary battery comprising a. . _{. .}