KR101926572B1 - Cathode active material for a lithium secondary battery, method of preparing for the same, and a lithium secondary battery comprising the same - Google Patents

Abstract

The present invention relates to a method for producing Li _x M _y BO ₃ By coating the surface of the lithium transition metal oxide particle with at least one element selected from the group consisting of M, Mn, Fe, Co, Ni, Cu and Zn and 0.9? X? 1.1 and 0.9? Y? Li ₂ O-2B ₂ O ₃ surface It is possible to provide a secondary battery in which high voltage characteristics are improved compared to a coated cathode active material, and side reactions with an electrolyte are minimized, thereby improving battery stability and cycle characteristics.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode active material for a lithium secondary battery, a method for producing the same, and a lithium secondary battery including the same. BACKGROUND ART [0002]

The present invention relates to a cathode active material for a lithium secondary battery, and more particularly, to a Li _x M _y BO ₃ By coating the surface of the lithium transition metal oxide particle with at least one element selected from the group consisting of M, Mn, Fe, Co, Ni, Cu and Zn and 0.9? X? 1.1 and 0.9? Y? To a secondary battery in which high voltage characteristics are improved and side reactions with an electrolyte are suppressed to improve cell stability and cycle characteristics.

2. Description of the Related Art In recent years, lithium secondary batteries have been used in many fields including portable electronic devices such as mobile phones, PDAs, and laptop computers. Especially, as the interest in environmental problems grows, it is one of the main causes of air pollution. As a driving source of electric vehicles that can replace fossil fuel vehicles such as gasoline vehicles and diesel vehicles, lithium secondary batteries Research on batteries has been actively conducted, and some of them are in the commercialization stage. On the other hand, in order to use a lithium secondary battery as a driving source of such an electric vehicle, it is necessary to maintain a stable output with a high output.

Therefore, it is required to develop new cathode materials capable of preventing deterioration of capacity during high-speed charging and discharging and improving battery characteristics, and methods for efficiently and economically manufacturing such cathode materials.

Boron (B, Boron) coatings have been applied to various cathode materials since their first application to LiMnO ₂ . Boron has a low melting point and low viscosity on the surface of the cathode material, which is advantageous in that it is uniformly coated on the surface of the cathode material.

Since boron on the surface of the cathode material is generally known to exist in the form of lithium borate glasses (Li ₂ O-2B ₂ O ₃ ) and lithium borate glasses form has lithium conductivity, boron coating on the surface of the cathode material Discharge capacity and charge / discharge efficiency are increased.

However, since lithium borate glasses exist in the form of uncrystallized glasses on the surface of the cathode material, if charging / discharging is repeated at high voltage, the shape of the glasses becomes unstable due to the change of anode material volume due to intercalation / deintercalation of Li and side reaction with electrolyte etc. , There is a problem that the cathode material can not perform the surface coating function properly.

Therefore, in order to apply a borate-based coating material to a high-voltage cathode material, it is necessary to apply a material having a structure having a high structural stability, not a glasses type.

As a result, the present inventors have found that the performance of the battery is improved when LiMnBO ₃ (lithium manganese borate) having a high structural stability is coated on the surface of lithium transition metal oxide particles.

The problem to be solved by the present invention is that Li _x M _y BO ₃ By coating the surface of the lithium transition metal oxide particle with at least one element selected from the group consisting of M, Mn, Fe, Co, Ni, Cu and Zn and 0.9? X? 1.1 and 0.9? Y? Li ₂ O-2B ₂ O ₃ surface And a secondary battery having improved high voltage characteristics compared to a coated cathode active material.

Another object of the present invention is to provide a secondary battery having improved battery stability and cycle characteristics by minimizing side reactions with an electrolyte by using the coating material having high structural stability.

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a lithium transition metal oxide particle, And a coating layer comprising a boron compound represented by the following formula (1) on the surface of the lithium-transition metal oxide particle.

[Chemical Formula 1]

Li _x M _y BO ₃ (M = at least one element selected from the group consisting of Mn, Fe, Co, Ni, Cu and Zn, 0.9? X? 1.1, 0.9? Y?

The present invention also provides a method for preparing a mixed solution comprising a) mixing a lithium precursor, M precursor (at least one element selected from the group consisting of M, Mn, Fe, Co, Ni, Cu and Zn) and a boron precursor in a non- ; b) preparing a reaction solution by reacting the mixed solution at a temperature of from 150 to 250 캜 under a condition of from 0.6 to 1.5 atm; c) cooling and washing the reaction solution to prepare crystal nuclei of a boron compound; d) dispersing the crystal nuclei in a solvent to prepare a coating solution; And e) mixing the coating solution and the lithium-transition metal oxide particles followed by heat-treating the cathode active material for a lithium secondary battery.

The present invention also provides a lithium secondary battery including a positive electrode active material for a lithium secondary battery according to the present invention, and a lithium secondary battery including the positive electrode for the lithium secondary battery.

The present invention relates to a method for producing Li _x M _y BO ₃ By coating the surface of the lithium transition metal oxide particle with at least one element selected from the group consisting of M, Mn, Fe, Co, Ni, Cu and Zn and 0.9? X? 1.1 and 0.9? Y? Li ₂ O-2B ₂ O ₃ surface It is possible to provide a secondary battery having improved high voltage characteristics compared to a coated cathode active material and minimizing side reactions with an electrolyte to improve battery stability and cycle characteristics.

1 is a SEM photograph (scale bar: 1.00 m) of a cathode active material (LiNi _0.6 Mn _0.2 Co _0.2 O ₂ ) coated with LiMnBO ₃ according to an embodiment of the present invention.
FIG. 2 is a graph showing a charge / discharge cycle for an initial 50 cycles of a lithium secondary battery manufactured according to an embodiment of the present invention.
FIG. 3 is a graph showing charge / discharge cycles for an initial 50 cycles of a lithium secondary battery manufactured according to a comparative example of the present invention.
FIG. 4 is a graph of charge / discharge characteristics measured after restoration of a lithium secondary battery according to an embodiment of the present invention for 3 days followed by 50 cycles.
FIG. 5 is a graph showing the charge / discharge characteristics of a lithium secondary battery manufactured according to a comparative example of the present invention after resting for 3 days and then performing 50 cycles.
6 is a graph of discharge capacity for the initial 50 cycles of the lithium secondary battery according to the example and the production example.
FIG. 7 is a graph of a discharge capacity measured after restoration of lithium secondary batteries according to Examples and Production Examples for 3 days and then 50 cycles.

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

The present invention relates to a lithium transition metal oxide particle; And a coating layer comprising a boron compound represented by the following formula (1) on the surface of the lithium-transition metal oxide particle.

[Chemical Formula 1]

Li _x M _y BO ₃ (M = at least one element selected from the group consisting of Mn, Fe, Co, Ni, Cu and Zn, 0.9? X? 1.1, 0.9? Y?

Boron (B, Boron) is known as an excellent ion conductor, and it is reported to be stable even in the potential range of 4 V. It is an element that is applied to various cathode active materials of lithium secondary batteries.

The coating layer containing the boron compound can reduce the surface area of the lithium-transition metal oxide particles, thereby restricting the reactivity with the electrolyte and filling the defects of the particle surface.

According to one embodiment of the present invention, in the Li _x M _y BO ₃ of Formula 1, M is at least one selected from the group consisting of Mn, Fe, Co, Ni, Cu, Zn), and most preferably, it may be manganese (Mn).

The form of the coating layer comprising the boron compound may be in the form of a single layer or a plurality of layers or in the form of an island. In the case of the layer form, the above effect can be expected due to the uniform coating, and in the case of the island type, the side reaction control effect is remarkably enhanced by selectively reacting with a specific active site on the surface of the lithium transition metal oxide particle, An effect of improving the thermal stability together can be expected.

According to an embodiment of the present invention, the boron compound may be 500 to 5000 ppm, more preferably 1000 to 3000 ppm, based on the total weight of the lithium transition metal oxide particles. When the amount of the boron compound is less than 1000 ppm, decomposition of electrolytic solution, inhibition of crystal structure collapse of lithium transition metal oxide, or ion conductivity may be deteriorated. When the boron compound is more than 3000 ppm, reduction in initial capacity and decrease in charge / .

According to an embodiment of the present invention, the thickness of the coating layer may be 10 to 100 nm, preferably 10 to 50 nm. When the thickness of the coating layer is less than 10 nm, the effect of coating of the boron compound may be insignificant. When the thickness of the coating layer is more than 100 nm, the initial capacity decrease and the electric conductivity at the surface of the lithium- There may be a problem in that degradation of the film is caused.

According to an embodiment of the present invention, the boron compound may include LiMnBO ₃ .

On the other hand, a material having a polyanion structure (for example, PO ₄ ^3- , SO ₄ ^2- , SiO ₄ ^{4 -,} BO ₃ ^3-, etc.) has a stable structure and is characterized by excellent high voltage and thermal stability. ₃ Li _x has a ^three- gujo _{M y BO 3 (M = Mn} , Fe, Co, Ni, and any one or more elements selected from the group consisting of Cu and Zn, 0.9≤x≤1.1, 0.9≤y≤1.1) Has a stable structure due to strong BO binding force similar to the PO ₄ ^3- structure, and LiPF ₆ To There is also an advantage that there is no side reaction with the basic electrolyte.

Among them, LiMnBO ₃ (lithium manganese borate) has a high energy storage capacity and can be applied to various energy storage media in addition to lithium secondary batteries.

According to an embodiment of the present invention, the lithium transition metal oxide particles include Li _x CoO ₂ (0.5 <x <1.3), Li _x NiO ₂ (0.5 <x <1.3), Li _x MnO _{2 ), Li x Mn 2 O 4} (0.5 <x <1.3), Li x (Ni a Co b Mn c) O 2 (0.5 <x <1.3, 0 <a <1, 0 <b <1, 0 <c <1, a + b + c = 1), Li x Ni 1 -y Co y O 2 (0.5 <x <1.3, 0 <y <1), LixCo 1 - y Mn y O 2 (0.5 <x <1.3 _{, 0≤y <1), Li x} Ni 1 -y Mn y O 2 (0.5 <x <1.3, O≤y <1), Li x (Ni a Co b Mn c) O 4 (0.5 <x <1.3 , 0 <a <2, 0 <b <2, 0 <c <2, a + b + c = 2), Li x Mn 2 - z Ni z O 4 (0.5 <x <1.3, 0 <z <2 ), Li _x Mn _{2 - z} Co _z O ₄ (0.5 ≦ _x ≦ 1.3, 0 ≦ z ≦ 2), Li _x CoPO ₄ (0.5 ≦ _x ≦ 1.3) and Li _x FePO ₄ And at least one selected from the group consisting of

 The present invention also relates to a method for preparing a mixed solution comprising a) mixing a lithium precursor, M precursor (at least one element selected from the group consisting of M, Mn, Fe, Co, Ni, Cu and Zn) and a boron precursor in a non- ; b) preparing a reaction solution by reacting the mixed solution at a temperature of from 150 to 250 캜 under a condition of from 0.6 to 1.5 atm; c) cooling and washing the reaction solution to prepare crystal nuclei of a boron compound; d) dispersing the crystal nuclei in a solvent to prepare a coating solution; And e) mixing the coating solution and the lithium-transition metal oxide particles followed by heat-treating the cathode active material for a lithium secondary battery.

According to an embodiment of the present invention, the non-aqueous solvent in step a) is a polyol having two or more hydroxyl groups in the molecule, such as ethylene glycol, 1,2-propanediol, 1,3- Butanediol, neopentyl glycol, pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 4,4'-dihydroxyphenylpropane, 4 , 4'-dihydroxymethylmethane, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, 1,4-cyclohexanedimethanol and 1,4-cyclohexanediol Lt; / RTI &gt;

The polyol is not particularly limited as long as it has two or more hydroxyl groups in the molecule, and any suitable polyol can be used.

According to an embodiment of the present invention, the lithium precursor in step a) is at least one selected from the group consisting of lithium chloride, lithium carbonate, lithium hydroxide, lithium oxalate, lithium acetate, lithium oxide, lithium sulfate, lithium phosphate and lithium nitrate &Lt; / RTI &gt;

The M precursor of step a) may be at least one selected from the group consisting of manganese chloride, manganese carbonate, manganese oxalate, manganese acetate, manganese oxide, manganese sulfate, manganese phosphate and manganese nitrate.

In addition, the boron precursor in step a) may be at least one selected from the group consisting of boric acid, orthoboric acid, metaboric acid, boric acid, boric acid, tetraboric acid and tetraboric acid, and polybasic acid and salts thereof.

As described above, the method of the present invention for producing a cathode active material for a lithium secondary battery is manufactured at a relatively low temperature of 0.6 to 1.5 atm using a nonaqueous solvent, and the advantage of a simple and cost- Lt; / RTI &gt;

According to an embodiment of the present invention, the reaction of step b) may be carried out for 1 to 24 hours. If the reaction time is less than 1 hour, the reaction between the precursors is difficult to occur. If the reaction time exceeds 24 hours, there is no process advantage because the reaction between the precursors is sufficiently performed.

According to an embodiment of the present invention, the washing in step c) may be carried out using ketones such as acetone or methyl ethyl ketone; Ethers such as tetrahydrofuran; Alcohols such as methanol, ethanol, propanol, isopropanol or butanol; Esters such as ethyl acetate and the like.

On the other hand, preparing the crystal nuclei before preparing the crystal of the boron compound in steps c) and d) and preparing the coating solution containing the crystal nuclei can reduce the total process time of the method for producing the cathode active material for a lithium secondary battery, This is because the nuclear state is more adhesive than the crystalline state, and the lithium transition metal oxide particles can be more uniformly coated on the surface thereof.

According to an embodiment of the present invention, the heat treatment in step e) may be performed at 300 to 800 ° C. When the heat treatment temperature is lower than 300 ° C, crystallization for forming a structurally stable coating layer may not be sufficiently performed. If the heat treatment temperature is higher than 800 ° C, the coating material may diffuse into the cathode material, There may be a problem.

The present invention also provides a lithium secondary battery positive electrode comprising the positive electrode active material for a lithium secondary battery according to the present invention, and a lithium secondary battery including the positive electrode for the lithium secondary battery.

The lithium secondary battery of the present invention can be produced by a conventional method known in the art. For example, a separation membrane may be placed between the anode and the cathode, and an electrolyte solution in which a lithium salt is dissolved may be added.

The electrode of the lithium secondary battery may also be manufactured by a conventional method known in the art. For example, a slurry is prepared by mixing and stirring a solvent, a binder, a conductive material, and a dispersant, if necessary, in a cathode active material or a negative electrode active material, applying the coating to a current collector of a metal material, Can be manufactured.

In particular, the positive electrode for a lithium secondary battery according to an embodiment of the present invention includes Li _x M _y BO ₃ By coating the surface of the lithium transition metal oxide particle with at least one element selected from the group consisting of M, Mn, Fe, Co, Ni, Cu and Zn and 0.9? X? 1.1 and 0.9? Y? It is possible to provide a secondary battery in which high voltage characteristics are improved and side reactions with an electrolyte are minimized to improve battery stability and cycle characteristics.

The positive electrode active material of the present invention is as described above, and the negative electrode active material is typically a carbonaceous material, lithium metal, silicon, or tin capable of intercalating and deintercalating lithium ions. Preferably, carbon materials can be used, and carbon materials such as low-crystalline carbon and highly-crystalline carbon can be used. Examples of the low crystalline carbon include soft carbon and hard carbon. Examples of highly crystalline carbon include natural graphite, Kish graphite, pyrolytic carbon, liquid crystal pitch carbon fiber high temperature sintered carbon such as mesophase pitch based carbon fiber, mesocarbon microbeads, mesophase pitches and petroleum or coal tar pitch derived cokes are representative.

The current collector of the metal material is a metal having high conductivity and easily adhered to the slurry of the electrode active material, and any material can be used as long as it is not reactive in the voltage range of the battery. Non-limiting examples of the positive electrode current collector include aluminum, nickel, or a foil produced by a combination of these. Non-limiting examples of the negative electrode current collector include copper, gold, nickel, or a copper alloy or a combination thereof Foil and so on.

The conductive material is not particularly limited as long as it can be generally used in the art, and examples thereof include synthetic graphite, natural graphite, carbon black, acetylene black, ketjen black, denka black, thermal black, channel black, carbon fiber, , Aluminum, tin, bismuth, silicon, antimony, nickel, copper, titanium, vanadium, chromium, manganese, iron, cobalt, zinc, molybdenum, tungsten, silver, gold, lanthanum, ruthenium, platinum, iridium, Polythiophene, polyacetylene, polypyrrole, or a combination thereof. In general, a carbon black-based conductive material may be used.

The binder is not particularly limited as long as it can be generally used in the art, and generally, a binder such as polyvinylidene fluoride (PVdF), a copolymer of polyhexafluoropropylene-polyvinylidene fluoride (PVdF / HFP), poly (Vinyl acetate), polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, alkylated polyethylene oxide, polyvinyl ether, poly (methyl methacrylate), poly (ethyl acrylate), polytetrafluoroethylene (PTFE) Polyvinyl chloride, polyacrylonitrile, polyvinylpyridine, styrene-butadiene rubber, acrylonitrile-butadiene rubber, ethylene propylene diene monomer (EPDM) or a mixture thereof may be used.

The electrolytic solution contained in the lithium secondary battery according to the present invention may be at least one selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethylsulfoxide (NMP), ethylmethyl carbonate (EMC), gamma butyrolactone (GBL), fluoroethylene carbonate (FEC), methyl formate (methyl ethyl ketone , At least one mixed organic solvent selected from the group consisting of ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, pentyl acetate, methyl propionate, ethyl propionate, ethyl propionate and butyl propionate.

Further, the electrolyte according to the present invention may further include a lithium salt, and the anion of the lithium salt may be an anion selected from the group consisting of F ^- , Cl ^- , Br ^- , I ^- , NO ₃ ^- , N (CN) ₂ ^- , BF ₄ ^{- _{ClO 4 -, PF 6 -,}} (CF 3) 2 PF 4 -, (CF 3) 3 PF 3 -, (CF 3) 4 PF 2 -, (CF 3) 5 PF -, (CF 3) 6 P - ^{_{, F 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) 3 C -, CF 3 (CF 2) 7 SO 3 -, CF 3 CO 2 -, CH 3 CO 2 -, SCN - and ( CF ₃ CF ₂ SO ₂ ) ₂ N ^- .

The secondary battery according to the present invention may be a cylindrical, square, or pouch type secondary battery, but is not limited thereto.

In addition, the present invention can provide a battery module including the lithium secondary battery as a unit cell and a battery pack including the same.

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

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

Example

1) Preparation of positive electrode for lithium secondary battery

Lithium hydroxide (LiOH · H ₂ O) in 500 ml of 1,4-butanediol, manganese acetate _{((CH 3 COO) 2 Mn} · 4H 2 O), boric acid in the first (HBO ₃₎ on a molar basis: 1: 1 ratio , And mixed to prepare a mixed solution. The mixed solution was introduced into an atmospheric pressure reactor, and the mixture was reacted for 1 to 24 hours while being heated to 190 to 220 ° C. After the completion of the reaction, the remaining reaction solution was cooled, washed with methanol to obtain LiMnBO ₃ A seed crystal was prepared. To prepare a coating solution by dispersing the appropriate concentration of the nucleated composite in ethanol, lithium nickel manganese cobalt oxide _{(LiNi 0. 6 Mn 0.} 2 Co 0. 2 O 2) 20 g and mixed with the lithium nickel manganese cobalt oxide The surface of the particles was coated with a concentration of 2000 ppm based on the total weight of the lithium nickel manganese cobalt oxide particles. Followed by heat treatment at 400 占 폚 in an air atmosphere.

The LiMnBO ₃ coated positive electrode active material _{(... LiNi 0 6 Mn} 0 2 Co 0 2 O 2), a binder (KF1100), conductive material (Super-C) 93, respectively: 4: solvent weight ratio of 3 (N -methyl-2-pyrrolidone, NMP) to prepare a positive electrode slurry.

The positive electrode slurry was coated on one surface of an aluminum (Al) thin film as a positive electrode current collector having a thickness of 20 占 퐉 and dried to prepare a positive electrode, followed by roll pressing to process the positive electrode.

2) Preparation of lithium secondary battery

Lithium metal was used as the cathode. The electrolytic solution was prepared by mixing ethylene carbonate (ethylene carbonate), diethyl carbonate (carbonate) and dimethyl carbonate (carbonate) in a volume ratio of 1: 1: Carbonate) was added 1 mol of LiPF ₆ .

The thus prepared positive electrode and negative electrode were combined with a separator to prepare a battery by a conventional method, and then the prepared electrolyte was injected to complete the preparation of a lithium secondary battery (coin cell).

Comparative Example

In the production of the embodiment of a lithium secondary battery positive electrode, and the boric acid (HBO ₃₎ non-LiMnBO ₃ lithium transition added 500 ppm total, based on the weight of the metal oxide particles, by heating at 300 ℃ for 5 hours, lithium borate glasses (Li ₂ O -2B ₂ O ₃ ) coating layer was formed in the same manner as in Example 1.

Experimental Example  1: Electron microscope ( SEM ) Photo shoot

An electron microscope (SEM) photograph was taken of the cathode active material (LiNi _0.6 Mn _0.2 Co _0.2 O ₂ ) surface-coated with LiMnBO ₃ prepared according to the above example (FIG. 1)

Experimental Example  2: Charging and discharging  Characterization

The charge and discharge characteristics of the lithium secondary battery produced according to the above Examples and Production Examples were measured in the range of 3.0 to 4.6 V according to the cycle. The rate of charge / discharge was measured at 0.5 C.

When the initial 50 cycles were carried out at 4.6 V, in the case of the comparative example (Fig. 3), the decrease width of the discharge capacity was larger than that of the example (Fig. 2).

 In the case of the comparative example (FIG. 5), the voltage at the initial stage of the discharge is continuously decreased as compared with the lithium secondary battery according to the embodiment (FIG. 4) . On the other hand, in the case of the embodiment, the initial discharge voltage maintained a constant level even when the cycle progressed.

In the comparative example, the lithium borate glasses (Li ₂ O-2B ₂ O ₃ ) coating layer is structurally unstable and side reactions with the electrolytic solution occur, and when charging and discharging are repeated at a high voltage, the transition metal Is eluted.

On the other hand, LiMnBO ₃ Is structurally stable, resulting in improved high-voltage characteristics and minimized side reactions with electrolytes, thereby improving battery stability and cycle characteristics.

Experimental Example  3: Measurement of discharge capacity

The discharge capacity of the lithium secondary battery manufactured according to the above Examples and Comparative Examples was measured in the range of 3.0 to 4.6 V according to the cycle. The rate of charge / discharge was measured at 0.5 C.

In the case of the initial 50 cycles at 4.6 V (FIG. 6), in the case of the comparative example, as the cycle progresses, the capacity decreases steadily while the embodiment decreases the capacity somewhat as the cycle progresses, Which is significantly smaller than that of the conventional method.

7). In the case of the comparative example, the discharge capacity was recovered to a level similar to that of the embodiment, but the discharging capacity after 25 cycles after the rest of 3 days (total of 75 cycles) It was confirmed that the temperature was rapidly lowered. On the other hand, it was confirmed that the decrease in the discharge capacity of the embodiment did not rapidly increase, and the capacity was maintained at a constant level.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (14)

Lithium transition metal oxide particles; And
And a coating layer comprising a boron compound represented by the following formula (1) on the surface of the lithium-transition metal oxide particle.
[Chemical Formula 1]
Li _x M _y BO ₃ (M = at least one element selected from the group consisting of Mn, Fe, Co, Ni, Cu and Zn, 0.9? X? 1.1, 0.9? Y?
The method according to claim 1,
Wherein the boron compound is present in an amount of 1000 to 3000 ppm based on the total weight of the lithium transition metal oxide particles.
The method according to claim 1,
Wherein the coating layer has a thickness of 10 to 100 nm.
The method according to claim 1,
The boron compound is a lithium secondary battery positive electrode active material comprising the LiMnBO _3.
The method according to claim 1,
The lithium transition metal oxide particles may include Li _x CoO ₂ (0.5 <x <1.3), Li _x NiO ₂ (0.5 <x <1.3), Li _x MnO ₂ (0.5 <x <1.3), Li _x Mn ₂ O ₄ 0.5 <x <1.3), Li x (Ni a Co b Mn c) O 2 (0.5 <x <1.3, 0 <a <1, 0 <b <1, 0 <c <1, a + b + c = Li _x Ni _{1 - y} Co _y O ₂ (0.5 <x <1.3, 0 <y <1), Li _x Co _{1 - y} Mn _y O _{2 x Ni 1 - y Mn y O} 2 (0.5 <x <1.3, O≤y <1), Li x (Ni a Co b Mn c) O 4 (0.5 <x <1.3, 0 <a <2, 0 < Li _x Mn _{2 - z} Ni _z O ₄ (0.5 <x <1.3, 0 <z <2), Li _x Mn _{2 - z} Co _z O ₄ (0.5 <x <1.3, 0 <z <2), Li _x CoPO ₄ (0.5 <x <1.3) and Li _x FePO ₄ (0.5 <x <1.3) And a positive electrode active material for a lithium secondary battery.
a) preparing a mixed solution by mixing a lithium precursor, an M precursor (at least one element selected from the group consisting of M, Mn, Fe, Co, Ni, Cu and Zn) and a boron precursor in a non-aqueous solvent;
b) preparing a reaction solution by reacting the mixed solution at a temperature of from 150 to 250 캜 under a condition of from 0.6 to 1.5 atm;
c) cooling and washing the reaction solution to prepare crystal nuclei of a boron compound;
d) dispersing the crystal nuclei in a solvent to prepare a coating solution; And
and e) mixing the coating solution and the lithium transition metal oxide particles and then heat-treating the lithium transition metal oxide particles.
The method according to claim 6,
The nonaqueous solvent in step a) is selected from the group consisting of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, Hexanediol, 1,8-octanediol, 1,10-decanediol, 4,4'-dihydroxyphenylpropane, 4,4'-dihydroxymethylmethane, diethylene glycol, triethylene glycol, polyethylene glycol, Dipropylene glycol, polypropylene glycol, 1,4-cyclohexanedimethanol, and 1,4-cyclohexanediol. 7. The method for producing a cathode active material for a lithium secondary battery according to claim 1,
The method according to claim 6,
The lithium precursor in step a) is at least one selected from the group consisting of lithium chloride, lithium carbonate, lithium hydroxide, lithium oxalate, lithium acetate, lithium oxide, lithium sulfate, lithium phosphate and lithium nitrate Wherein the positive electrode active material is a lithium secondary battery.
The method according to claim 6,
The M precursor in step a) includes at least one selected from the group consisting of manganese chloride, manganese carbonate, manganese oxalate, manganese acetate, manganese oxide, manganese sulfate, manganese phosphate and manganese nitrate. A method for manufacturing a cathode active material for a battery.
The method according to claim 6,
Wherein the boron precursor in step a) comprises at least one selected from the group consisting of boric acid, orthoboric acid, metaboric acid, polybasic acid such as boric acid, tetraboric acid and tetraboric acid, and salts thereof. A method for producing a cathode active material.
The method according to claim 6,
Wherein the reaction time in the step b) is 1 to 24 hours.
The method according to claim 6,
Wherein the heat treatment in step e) is performed at 300 to 800 ° C.
A positive electrode for a lithium secondary battery comprising the positive electrode active material for a lithium secondary battery according to any one of claims 1 to 5.
14. A lithium secondary battery comprising a positive electrode for a lithium secondary battery according to claim 13.

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