KR100578447B1 - Process for manufacturing nano-crystalline cathode material for high rate lithum rechargeable battery by self-mixing method - Google Patents

Abstract

The present invention provides a self-mixing eutectic method that can economically and easily produce layered nanoparticle lithium / nickel / cobalt oxide and spinel structured nanoparticle lithium / manganese oxide using a single heat treatment process integrating material synthesis and nano atomization. The present invention relates to a method for preparing a crystalline nanoparticle positive electrode active material for a high power lithium secondary battery using a melting point between 25 and 200 ° C. in order to achieve material synthesis and nano atomization in a single heat treatment process. A first step of basis weighting at least two metal compounds having a range of 5 to 50 ° C. at an appropriate molar ratio; A second step of obtaining a homogeneous fluid mixture by self-mixing eutectic at a temperature between 25-150 ° C .; The mixture is calcined and sintered under a precise control of a carbon dioxide atmosphere at a temperature of 200-900 ° C. and a constant pressure, thereby producing a composite metal oxide.

According to the present invention, it is possible to simplify the structure of the process to save the facility equipment costs and production costs corresponding to these processes.

High output lithium secondary battery, self mixing eutectic method, positive electrode active material manufacturing method

Description

Process for manufacturing nano-crystalline cathode material for high rate lithum rechargeable battery by self-mixing method}

Figure 1a is a characteristic diagram showing the results of the thermal weight method and differential thermal analysis of the reactants for the preparation of the spinel structured nanoparticles LiMn ₂ O ₄ according to the present invention,

Figure 1b is a characteristic diagram showing the results of the thermal weight method and the differential thermal analysis of the reactants for the production of layered nanoparticles LiNi _0.7 Co _0.3 O ₂ according to the present invention,

Figure 2a is a process flow diagram illustrating a method for manufacturing a spinel structure nanoparticles LiMn ₂ O ₄ according to the present invention,

Figure 2b is a process flow diagram illustrating a method of manufacturing a layered nanoparticle lithium / nickel / cobalt oxide LiNi _1-x Co _x O ₂ (0.2 ≤ x ≤ 0.5) according to the present invention,

Figure 3a is a characteristic diagram showing the X-ray diffraction pattern of the nanoparticles LiMn ₂ O ₄ prepared according to the present invention,

3b is a characteristic diagram showing an X-ray diffraction pattern of nanoparticles LiNi _1-x Co _x O ₂ (0.2 ≤ x ≤ 0.5) prepared according to the present invention,

Figure 4a is a scanning electron micrograph of the surface of the nanoparticles LiMn ₂ O ₄ powder prepared according to the present invention,

Figure 4b is a scanning electron micrograph of the surface of the particulate LiMn ₂ O ₄ powder prepared according to Comparative Example 1,

Figure 5a is a scanning electron micrograph of the surface of the nanoparticles LiNi _0.7 Co _0.3 O ₂ powder prepared according to the present invention,

5b is a scanning electron micrograph of the surface of the particulate LiNi _0.7 Co _0.3 O ₂ powder prepared according to Comparative Example 2,

6A is a graph showing charge and discharge capacity characteristics of a lithium secondary battery using nanoparticles LiNi _0.7 Co _0.3 O ₂ prepared according to the present invention at various output ratios,

6B is a graph showing charge and discharge capacity characteristics of a lithium secondary battery using particulate LiNi _0.7 Co _0.3 O ₂ prepared according to Comparative Example 2 at various output ratios.

The present invention relates to an economical manufacturing method of crystalline nanoparticulate positive electrode active material for high power lithium secondary batteries using a self-mixing eutectic method, and more specifically, a high temperature solid-state reaction method / high-temperature solid-state reaction method, which is a variety of existing methods for preparing nanoparticle positive electrode active material It is a synthetic method that overcomes the disadvantages of complex multi-stage process, expensive production cost, consumption of many materials and energy, such as energy crushing method, spray pyrolysis method, coprecipitation method / microwave sintering method, sol-gel method / micro-template heat treatment method, etc. The self-mixing eutectic method utilizes spontaneous eutectic mixing to control the reaction atmosphere that suppresses crystal growth and promotes crystal nucleation at a specific temperature without any artificial reactant mixing process. Economically and Easily Produce Crystalline Nanoparticulate Cathode Active Materials Only in Process The present invention relates to an economical manufacturing method of a crystalline nanoparticulate positive electrode active material for a high output lithium secondary battery using a self-mixing eutectic.

The layered nanoparticle lithium / nickel / cobalt oxide and spinel structure nanoparticle lithium / manganese oxide prepared according to the present invention may be used as a positive electrode active material of a high power and high efficiency lithium secondary battery.

Lithium secondary batteries are in the spotlight as high-efficiency energy storage devices for electric and electronic devices.They are not only portable electronics such as IMT2000, PDA, web pad, tablet PC, sub notebook, GPS, etc. As the functions of medium and large devices are diversified, the demand is increasing rapidly with increasing demand for high power and high efficiency characteristics of energy sources.

In addition, there is a need for production and development of lithium secondary batteries having high efficiency of 2C or higher required for efficient operation such as high-speed wireless transmission and storage of data, driving of data processing and conversion systems, and real-time display of high-speed conversion data.

Meanwhile, essential components of the lithium secondary battery are a negative electrode, an electrolyte and a positive electrode, and a lithium secondary battery is a lithium metal battery using a lithium metal negative electrode and an organic solvent electrolyte, a carbon negative electrode and an organic solvent depending on the type of negative electrode material and electrolyte. A lithium ion battery using an electrolyte, a lithium metal polymer battery using a lithium metal negative electrode and a solid polymer electrolyte, and a lithium ion polymer battery using a carbon negative electrode and a solid polymer electrolyte.

However, regardless of the type of lithium secondary battery, the first problem to be solved in order to obtain a high output and high efficiency lithium secondary battery is to develop a technology capable of economically mass-producing a cathode active material with improved output and energy efficiency.

The positive electrode active material may be commonly used regardless of the type of lithium secondary battery. Representative positive electrode active materials are lithium / cobalt oxide such as LiCoO ₂ having a layered structure, lithium / nickel oxide such as LiNiO ₂ , and LiMn having a spinel structure. Lithium / manganese oxides such as ₂ O ₄ . In addition, in order to obtain a lithium secondary battery having a high energy density and a long lifespan, a solid solution compound substituted with a second transition metal, that is, a general formula LiNi _1-x M _x O _2, is represented by M is Co, Al, Mg, Cr. Lithium / nickel / metal oxides of Cu, Mn, Fe, or Ti, and lithium / manganese represented by the general formula LiMn _2-x M _x O ₄ , wherein M is Co, Ni, Al, Mg, Cr, Cu, Fe, or Ti Metal oxides may be used.

Since the electron conductivity is much higher than the ion conductivity, the difference in lithium ion concentration in the cathode active material particles during the charging and discharging process of the lithium secondary battery causes energy loss and low power of the battery due to concentration polarization. Therefore, in order to secure a high output, high efficiency and long life lithium secondary battery, it is necessary to secure a large diffusion path of lithium ions or improve the diffusion rate. In order to achieve this object, it is the most suitable solution to make the specific surface area of the positive electrode active material particles uniform and ultrafine.

Accordingly, research and technology development for ultra minimizing the particle size of the crystalline cathode active material have been actively conducted.

Existing methods for preparing the crystalline nanoparticle positive active material are largely classified into four types. First, high-temperature solid-state reaction / high energy pulverization method of pulverizing, mixing, and assembling solid phase reactant, calcining and sintering at high temperature to obtain layered lithium / cobalt oxide, and then physically pulverizing with strong mechanical strength to obtain nanoparticles. Is a spray pyrolysis method in which a solvent obtained by dissolving a reactant in a solvent is evaporated while evaporating the solvent to obtain a particulate gel, and the particulate gel is heat treated to obtain nanoparticles. In parallel with the treatment, fine precipitates were obtained, dried, and then coagulated / microwave sintered and pulverized, mixed, granulated, calcined, sintered and microwave treated with lithium salts. Fourth, solid reactants were dissolved in a solvent to obtain a solution. Solgel method / Ultrafine which inhales the solution into the micro-mould, evaporates the solvent to obtain the gel, and then heat-treats the gel A type annealing method.

The high temperature solid state reaction / high energy pulverization method, which is one of the existing manufacturing methods, is complicated to crush and mix in order to obtain a single phase crystalline phase as the production volume increases, and to obtain a positive electrode active material by high temperature heat treatment process and then change the shape into nano-sized particles. Because of the physical grinding while consuming high energy has the disadvantage of high process cost.

Spray pyrolysis is spontaneous mixing in a solution in which solid phase reactants are dissolved, thus eliminating the need for grinding, mixing and assembling processes as in high temperature solid state reaction / high energy grinding methods. However, since solvents or solvents are used as raw materials in addition to the essential chemical components to dissolve the reactants, a heat treatment process more than necessary to remove them is added later, which causes a lot of energy loss and consumes materials other than the essential chemical components. Uneconomical In addition, particle size and particle size distribution may not be uniform due to coagulation between the fine particle gels during the high temperature heat treatment process.

The coprecipitation method / microwave sintering method has the disadvantage that the whole process is complicated, the process time is long, and the atomization effect is relatively low.

The sol-gel method / ultra-template heat treatment method inhales the solution in which the solid phase reactant is dissolved into the ultra-mould, evaporates the solvent to obtain a gel, and then burns the expensive ultra-mould during the high temperature heat treatment of the gel. It is economical.

The present invention was devised to solve the drawbacks of the conventional methods for preparing the crystalline nanoparticles positive electrode active material as described above, using spontaneous eutectic mixing without any artificial reactant mixing process, and controls the reaction atmosphere at a specific temperature. High power output using the self-mixing eutectic method to produce layered nanoparticle lithium / nickel / cobalt oxide and spinel structure nanoparticle lithium / manganese oxide economically and easily with a single heat treatment process integrating material synthesis and nano atomization process It is an object of the present invention to provide an economical method for producing a crystalline nanoparticulate positive electrode active material for a lithium secondary battery.

In order to achieve the above object, the present invention has a melting point between 25 and 200 ° C. and a melting point of 5 to 50 ° C. in order to achieve a single heat treatment process in which material synthesis and nano atomization are integrated. A first step of weighing two or more metal compounds in an appropriate molar ratio; A second step of obtaining a homogeneous fluid mixture by self-mixing eutectic at a temperature between 25-150 ° C .; The mixture is calcined and sintered under a precise control with a carbon dioxide atmosphere at a temperature between 200-900 ° C. and a pressure of 0.001-5 kgf / cm 2, thereby producing a composite metal oxide.

According to the results obtained by the experiment, when carbon dioxide with a pressure of 0.001-5 kgf / cm 2 was supplied from the outside, crystal growth was suppressed and crystal nucleation was promoted to obtain nanoparticles.

In other words, if the pressure of carbon dioxide supplied from the outside is 0.001 kgf / cm 2 or less, crystal growth is not suppressed, and the grain size of lithium / cobalt oxide is increased. Not only does the disadvantage occur but crystal growth is suppressed excessively, a pressure range of 0.001-5 kgf / cm 2 is preferable.

The at least two metal compounds may be selected from manganese acetate tetrahydrate, nickel acetate tetrahydrate, cobalt acetate tetrahydrate, hydroxy aluminum acetate, iron acetate and iron acetylacetonate based on lithium acetate dihydrate. The above can be selected.

In this case, the composite metal oxide is formed of a composite metal oxide of lithium / manganese / metal (M) of LiMn _2-x M _x O ₄ (0 ≦ x ≦ 1), or LiNi _1-x M _x O ₂ ( 0 ≦ x ≦ 1) It may be formed of a composite metal oxide of lithium / nickel / metal (M) of the formula.

More specifically, when the composite metal oxide is LiMn _2-x M _x O ₄ (0 ≦ x ≦ 1) lithium / manganese / metal (M), the metal (M) is Ni, Co, It is selected from the group consisting of Al and Fe, it is also produced as a lithium / manganese oxide of x = 0 in the formula.

As described above, in the case of producing lithium / manganese oxide, it is preferable that the mixing molar ratio of the lithium compound and the manganese compound is 1.03: 2.0 as the initial reactant.

On the other hand, when the composite metal oxide is formed of a composite metal oxide of Li / nickel / metal (M) of LiNi _1-x M _x O ₂ (0 ≤ x ≤ 1), the metal (M) is Co, Mn, It may be selected from the group consisting of Al and Fe.

The reason for substituting a part of nickel with the metal (M) in this way is to improve the structural stability of the positive electrode active material.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention utilizes spontaneous eutectic mixing of reactants having a melting point of 25 to 200 ° C. and a difference of melting point of 5 to 50 ° C., and generates a constant pressure of carbon dioxide gas from a outside at a specific temperature between 200 and 900 ° C. This can be achieved by performing a second, single heat treatment process that integrates material synthesis and nano-atomization by suppressing crystal growth and promoting nucleation. Here, the reason for limiting the melting point difference to the range of 5-50 ° C is that the experiment shows that when the difference in melting point is 50 ° C or higher, the self-mixing does not occur sufficiently because the holding of the eutectic state is short, so that the maintenance of the eutectic state is the most. The long 5-50 ° C region was chosen.

In addition, the reason for proceeding the material synthesis and nano-atomization process at a specific temperature between 200-900 ℃, the phase transition must occur in order to obtain the positive electrode active material of the desired crystal structure, the minimum temperature required for the phase transition is 200 ℃, 900 This is because the crystal structure of the desired positive electrode active material is destroyed at a temperature higher than the temperature.

For example, in the method for producing the layered lithium / nickel / cobalt oxide and the spinel structured lithium / manganese oxide, it is not necessary to use a solvent or a solvent to obtain a fluid.

That is, fluids can be obtained when minimal reactants containing the essential constituents of lithium / nickel / cobalt oxide and lithium / manganese oxide melt themselves in the absence of solvent, and these fluids will spontaneously mix uniformly. Can be.

More specifically, compounds having low melting points such as lithium acetate dihydrate (melting point: 60 ° C.), manganese acetate tetrahydrate (melting point: 68 ° C.), and nickel acetate tetrahydrate (melting point: 107 ° C.) They spontaneously mix as they are eutectic and fluid at temperatures slightly above the melting point of the compounds to be combined.

On the other hand, in the case of cobalt acetate tetrahydrate (melting point: 298 ° C.), the melting point of the cobalt acetate tetrahydrate is relatively high, so that it does not melt on its own. Some melt on

Therefore, when cobalt acetate tetrahydrate, lithium acetate dihydrate, and nickel acetate tetrahydrate are present together, fluids may form even at a temperature of about 110 ° C., resulting in spontaneous eutectic mixing.

Figure 1a is a characteristic diagram showing the results of the thermogravimetric and differential thermal analysis of the reactants for the preparation of the spinel structure nanoparticles LiMn ₂ O ₄ according to the present invention, from the above self-mixing eutectic phenomenon and 200-900 ℃ Spinel structure lithium / manganese oxide manufacturing reaction process according to the heat treatment process can be seen.

That is, the characteristic diagram of FIG. 1A shows that there are two mass loss steps between room temperature and 250 ° C. The first mass loss step occurs between room temperature and 170 ° C. with a mass loss rate of 29.5%, and the second mass loss step occurs between 170 ° C. and 250 ° C. with a mass loss rate of 38.8%. Based on these results, the reaction equation according to the heat treatment process is as follows.

Reaction between temperatures 25-170 ° C:

LiCH ₃ CO ₂ · 2H ₂ O + 2Mn (CH ₃ CO ₂ ) ₂ · 4H ₂ O → LiMn ₂ (CH ₃ CO ₂ ) ₅ + 10H ₂ O

Reaction between temperatures 170-250 ° C:

LiMn ₂ (CH ₃ CO ₂ ) ₅ + 10.75 O ₂ → LiMn ₂ O ₄ + 7.5H ₂ O + 10CO ₂

Looking at the reaction equation occurring between 170 ℃ and 250 ℃ it can be seen that carbon dioxide gas is generated while the spinel structure lithium / manganese oxide is obtained.

At temperatures above 250 ° C, no mass loss, endothermic and exothermic reactions occur. Therefore, supplying and precisely controlling carbon dioxide gas from the outside at a specific pressure at a temperature near 250 ° C means that crystal growth can be suppressed and crystal nucleation can be promoted.

On the other hand, Figure 1b is a characteristic diagram showing the results of the thermogravimetric method and differential thermal analysis of the reactants for the production of layered nanoparticles LiNi _0.7 Co _0.3 O ₂ according to the present invention, from the self-mixing eutectic phenomenon and 200-900 It can be seen that the layered lithium / nickel / cobalt oxide manufacturing reaction process according to the heat treatment step of ℃.

1b shows that there are two mass loss steps between room temperature and 300 ° C. The first mass loss step occurs between room temperature and 100 ° C. with a mass loss rate of 30.8%, the second mass loss step occurs between 100 ° C. and 300 ° C. with a mass loss rate of 40.2%. Based on these results, the reaction equation according to the heat treatment process is as follows.

Reaction in the temperature 25-100 ° C. range:

LiCH ₃ CO ₂ · 2H ₂ O + 0.7Ni (CH ₃ CO ₂ ) ₂ · 4H ₂ O + 0.3Co (CH ₃ CO ₂ ) ₂ · 4H ₂ O → LiNi _0.7 Co _0.3 (CH ₃ CO ₂ ) ₃ + 6H ₂ O

Reaction in the temperature range 100-300 ° C:

LiNi _0.7 Co _0.3 (CH ₃ CO ₂ ) ₃ + 6.25 O ₂ → LiNi _0.7 Co _0.3 O ₂ + 4.5H ₂ O + 6CO ₂

Looking at the reaction equations occurring in the step 100 ℃ and 300 ℃ it can be seen that carbon dioxide gas is generated while the layered lithium / nickel / cobalt oxide is obtained. At temperatures above 300 ° C., no mass loss, endothermic and exothermic reactions occur. Therefore, supplying and precisely controlling carbon dioxide gas from outside to a pressure of 0.001-5 kgf / cm 2 at a temperature near 300 ° C means that crystal growth can be suppressed and crystal nucleation can be promoted.

In the present invention, the self-mixing eutectic phenomenon and the gas phase generated by the reaction at a specific temperature, rather than supplied and precisely controlled at a certain pressure from the outside to suppress crystal growth and promote crystal nucleation, thereby synthesizing the material synthesis and nano atomization process. Using this integrated single heat treatment process, it provides an economical and convenient way to produce layered nanoparticle lithium / nickel / cobalt oxide and spinel structured nanoparticle lithium / manganese oxide.

First, a method for preparing a spinel structure nanoparticle lithium / manganese oxide using an integrated self-mixing eutectic method according to the present invention will be described with reference to FIG. Figure 2a is a process flow diagram illustrating a method for producing nanoparticles LiMn ₂ O ₄ according to the present invention.

Starting materials for preparing the spinel structured nanoparticle lithium / manganese oxide according to the present invention include lithium acetate 2 hydrate (CH ₃ CO ₂ Li 2H ₂ O) and manganese acetate 4 hydrate ((CH ₃ CO ₂ )). ₂ Mn. 4H ₂ O), and each of them is first weighed in the correct molar ratio. Herein, the mixing molar ratio of the lithium compound and the manganese compound for preparing the spinel structure nanoparticle lithium / manganese oxide is 1.03: 2.0.

On the other hand, lithium acetate hydrate is preferably used in an excess of 3 mol% because the atomic weight of lithium is very small and the vapor pressure is high. In addition, the starting material in the present invention can be used irrespective of particle size and particle size distribution.

The lithium acetate dihydrate _{(CH 3 CO 2 Li · 2H} 2 O) and manganese acetate · tetrahydrate in 70 ℃ of _{((CH 3 CO 2) 2} Mn · 4H 2 O) a self-mixing the eutectic temperature, 40 - 50 After the heat treatment for minutes, the reactants are eutectic and spontaneously and uniformly mixed.

Thus, a homogeneous fluid mixture was obtained, which was then calcined at 250 ° C. for 8 hours under a precisely controlled atmosphere of carbon dioxide at 0.02 kgf / cm ² and sintered at 800 ° C. for 20 hours in air to produce a positive electrode for a high power lithium secondary battery. A crystalline spinel structure nanoparticle lithium / manganese oxide that can be used as an active material is obtained.

On the other hand, the method for producing a layered nanoparticle lithium / nickel / cobalt oxide using an integrated self-mixing eutectic method according to the present invention will be described with reference to Figure 2b. Figure 2b is a process flow diagram illustrating a method of manufacturing a layered nanoparticle lithium / nickel / cobalt oxide LiNi _1-x Co _x O ₂ (0.2 _{≤ x ≤} 0.5) according to the present invention.

By implementing the present invention the layer structure nanoparticles lithium / nickel / a starting material for the production of cobalt oxide, lithium acetate dihydrate _{(CH 3 CO 2 Li · 2H} 2 O), nickel acetate · tetrahydrate ((CH ₃ CO ₂ ) ₂ Ni.4H ₂ O) and cobalt acetate.4 hydrate ((CH ₃ CO ₂ ) ₂ Co.4H ₂ O), each of these starting materials being weighed in the correct molar ratio.

Here, the molar ratio of lithium, nickel and cobalt for the production of the layered nanoparticle lithium / nickel / cobalt oxide is 1.03: 1-x: x, where x should be 0 ≦ x ≦ 1, preferably 0.2 ≦ x ≦ 0.5.

The lithium acetate hydrate is preferably used in an amount of 3 mol% over the quantitative molar ratio because the atomic amount of lithium is very small and the vapor pressure is high, and the starting material in the present invention can be used regardless of particle size and particle size distribution. have.

After the basis weight in a molar ratio, and lithium acetate dihydrate _{(CH 3 CO 2 Li · 2H} 2 O), nickel acetate · tetrahydrate _{((CH 3 CO 2) 2} Ni · 4H 2 O) and cobalt acetate-tetrahydrate (( When CH ₃ CO ₂ ) ₂ Co.4H ₂ O) is heat treated at 110 ° C. for a self-mixing eutectic temperature for 40-50 minutes, the reactants are eutectic and spontaneously and uniformly mixed.

When a homogeneous fluid mixture is obtained, it is calcined for 8 hours at 300 ° C. under a precisely controlled atmosphere with carbon dioxide at 0.01 kgf / cm ² and sintered at 800 ° C. for 20 hours in air. A crystalline layered nanoparticle lithium / nickel / cobalt oxide that can be used as a positive electrode active material for batteries is obtained.

Spinel-structured nanoparticle lithium / manganese oxide LiMn ₂ O prepared by the integrated self-mixing eutectic method by the result of X-ray diffraction analysis of the nanoparticle lithium / manganese oxide prepared by the integrated self-mixing eutectic method as described above. ₄ is a spinel structure having a space group Fd3m and confirmed by X-ray diffraction pattern analysis.

Then, from the results of X-ray diffraction analysis of the layered nanoparticle lithium / nickel / cobalt oxide prepared by the integrated self-mixing eutectic method as described above, the layered nanoparticle lithium / It was confirmed that the nickel / cobalt oxide LiNi _1-x Co _x O ₂ (0.2 ≦ x ≦ 0.5) was a layered structure having a space group R-3m.

Figure 4a is a scanning electron micrograph of the surface of the nanoparticles LiMn ₂ O ₄ powder prepared according to the present invention, Figure 4b is a scanning electron micrograph of the surface of the nanoparticles LiMn ₂ O ₄ powder prepared according to Comparative Example 1, 5a is a scanning electron micrograph of the surface of the nanoparticles LiNi _0.7 Co _0.3 O ₂ powder prepared according to the present invention, Figure 5b is a scanning electron micrograph of the surface of the nanoparticles LiNi _0.7 Co _0.3 O ₂ powder prepared according to Comparative Example 2. to be. These photos show the powder form and approximate particle size of each product.

The comparative example was self-mixed for 40 minutes at 110 ° C. and then calcined for 8 hours at 300 ° C. in air, not for a precisely controlled atmosphere with carbon dioxide at 0.01 kgf / cm ² , and for 20 hours at 800 ° C. in air. It is manufactured by sintering.

The layered nanoparticle lithium / nickel / cobalt oxide LiNi _0.7 Co _0.3 O ₂ prepared according to the present invention may be used as a cathode active material of a lithium secondary battery.

Hereinafter, the lithium secondary battery composition and battery performance test results containing the layered nanoparticle lithium / nickel / cobalt oxide LiNi _0.7 Co _0.3 O ₂ prepared in the same manner as described above will be described.

In 80 wt% of the nanoparticulate lithium / nickel / cobalt oxide LiNi _0.7 Co _0.3 O ₂ sample prepared according to the present invention, 10 wt% of acetylene black as the conductive material, polytetrafluoroethylene (hereinafter referred to as “PTFE”) as a binder 10% by weight of the positive electrode was prepared. As another example, 80% by weight of a layered lithium / nickel / cobalt oxide LiNi _0.7 Co _0.3 O ₂ sample prepared without the nano-atomization condition, 10% by weight of acetylene black as a conductive material and 10% by weight of PTFE as a binder Was added to prepare a positive electrode.

Ethylene carbonate (hereinafter referred to as "EC") and dimethyl carbonate (hereinafter referred to as "DMC") 1: 1 LiPF ₆ is dissolved in a mixed solvent to form a 1M solution. A lithium battery was constructed using the foil as a negative electrode, and performance tests of these batteries were performed in the following manner.

The charge and discharge experiments of the fabricated and assembled batteries were carried out using a constant current method that constantly flows six specific currents of 0.1C, 0.2C, 0.5C, 1.0C, 2.0C, and 3.0C in the 3.0-4.2V range. .

The charge and discharge characteristics of the battery including the nanoparticulate lithium / nickel / cobalt oxide LiNi _0.7 Co _0.3 O ₂ prepared according to the present invention are as shown in FIG. 6A. Figure 6a is prepared according to the present invention, that is, self-mixing for 40 minutes at 110 ° C and then calcined for 8 hours at 300 ° C under a precisely controlled atmosphere of carbon dioxide at 0.01 kgf / cm ² pressure, at 800 ° C in air Nanoparticle lithium / nickel / cobalt oxide LiNi _0.7 Co _0.3 O ₂ battery charge and discharge characteristics prepared by sintering for 20 hours, and the initial discharge capacity characterized by constant current of 0.1C is 170.75 mAh / g (3.0-4.2 V) The discharge capacity, which was characterized by a constant current of 3.0C by increasing the output 30 times, was 159.32 mAh / g (3.0-4.2 V), so the discharge capacity retention rate was 93.3%.

Figure 6b is prepared by the comparative example, that is, self-mixing eutectic for 40 minutes at 110 ℃, calcined for 8 hours at 300 ℃ temperature in air, not carbon dioxide atmosphere, and sintered at 800 ℃ in air for 20 hours Battery charge and discharge characteristics of the prepared lithium / nickel / cobalt oxide LiNi _0.7 Co _0.3 O ₂ , the initial discharge capacity was characterized by a constant current of 0.1C 167.77 mAh / g (3.0-4.2 V), the output 30 times increased The discharge capacity, which was characterized by a constant current of 3.0 C, was 142.45 mAh / g (3.0-4.2 V), so the discharge capacity retention rate was 84.9%.

These results show that the high output characteristics were greatly increased when the nanoparticulate lithium / nickel / cobalt oxide LiNi _0.7 Co _0.3 O ₂ prepared economically and easily as the cathode active material of a lithium secondary battery.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the embodiments are only illustrative of the present invention, and the scope of the present invention is not limited thereto.

Example 1

Preparation of Spinel Structured Nanoparticulate Lithium / Manganese Oxides Using the Manufacturing Method of the Present Invention

31.52 g (0.309 mole) of lithium acetate.2 hydrate (CH ₃ CO ₂ Li.2H ₂ O) and 147.06 g (0.6 mole) of manganese acetate.4 hydrate ((CH ₃ CO ₂ ) ₂ Mn.4H ₂ O. Were put together in an alumina crucible and self-mixed eutectic at 70 ° C. for 40 minutes. The melt is then calcined at 250 ° C. for 8 hours under a precisely controlled atmosphere of carbon dioxide at 0.02 kgf / cm ² and sintered at 800 ° C. for 20 hours in air to spinel structured nanoparticle lithium / manganese oxide LiMn ₂ O ₄ Got.

The crystal structure of the product was confirmed by X-ray diffraction analysis, the results are shown in Figure 3a. The nanoparticulate lithium / manganese oxide LiMn ₂ O ₄ powder prepared by the above method was found to have a spinel structure having a space group Fd3m, and the size of the nanoparticles was confirmed by scanning electron micrograph (FIG. 4A).

Comparative Example 1

In order to compare with the results of the Example, the spinel structure lithium / manganese oxide LiMn ₂ O ₄ was prepared in the same manner as in Example 1 except that calcination and sintering in air without supplying carbon dioxide.

At this time, the particle size of the product, as shown in Figure 4b, it was confirmed by scanning electron micrograph that the unit of micrometer.

Example 2

Layered Nanoparticulate Lithium / Nickel / Cobalt Oxide (LiNi) _0.7 Co _0.3 O ₂ Manufacturing

31.52 g (0.309 mole) of lithium acetate.2 hydrate (CH ₃ CO ₂ Li.2H ₂ O), 53.34 g (0.21 mole) of nickel acetate.4 hydrate ((CH ₃ CO ₂ ) ₂ Ni.4H ₂ O.) And 22.86 g (0.09 mol) of cobalt acetate.4 hydrate ((CH ₃ CO ₂ ) ₂ Co.4H ₂ O) were placed together in an alumina crucible and self-mixed at 40 ° C. for 40 minutes. The melt is then calcined at 300 ° C. for 8 hours in a precisely controlled atmosphere with carbon dioxide at 0.01 kgf / cm ² and sintered at 800 ° C. for 20 hours in air to form nanoparticle lithium / nickel / cobalt oxide LiNi _0.7 Co _0.3 O ₂ was obtained.

Comparative Example 2

For comparison with the results of the examples, lithium / nickel / cobalt oxide LiNi _0.7 Co _0.3 O ₂ was prepared in the same manner as in Preparation Example 2, except that calcination and sintering in air was performed without supplying carbon dioxide. .

At this time, the particle size of the product was confirmed by scanning electron micrographs, as shown in Figure 5b, the micrometer unit.

Example 3

Layered structure nanoparticle lithium / nickel / cobalt oxide using the manufacturing method of the present invention (LiNi _0.8 Co _0.2 O ₂ Manufacturing

31.52g lithium acetate dihydrate of (0.309 mol) of nickel acetate tetrahydrate, the _{(CH 3 CO 2 Li · 2H} 2 O), 60.96g (0.24 mol) of ((CH ₃ CO _{2) 2} Ni · 4H ₂ O) And 15.24 g (0.06 mole) of cobalt acetate.4 hydrate ((CH ₃ CO ₂ ) ₂ Co.4H ₂ O) were placed together in an alumina crucible and self-mixed at 110 ° C. for 40 minutes. The melt is then calcined at 300 ° C. for 8 hours in a precisely controlled atmosphere with carbon dioxide at 0.01 kgf / cm ² and sintered at 800 ° C. for 20 hours in air to form nanoparticle lithium / nickel / cobalt oxide LiNi _0.8 Co _0.2 O ₂ was obtained.

Example 4

Layered structure nanoparticle lithium / nickel / cobalt oxide using the manufacturing method of the present invention (LiNi _0.6 Co _0.4 O ₂ Manufacturing

31.52g lithium acetate dihydrate of (0.309 mol) of nickel acetate tetrahydrate, the _{(CH 3 CO 2 Li · 2H} 2 O), 45.72g (0.18 mol) of ((CH ₃ CO _{2) 2} Ni · 4H ₂ O) And 30.48 g (0.12 mole) of cobalt acetate.4 hydrate ((CH ₃ CO ₂ ) ₂ Co.4H ₂ O) were placed together in an alumina crucible and self-mixed at 110 ° C. for 40 minutes. The melt is then calcined at 300 ° C. for 8 hours under precisely controlled atmosphere with carbon dioxide at 0.01 kgf / cm ² and sintered at 800 ° C. for 20 hours in air to form nanoparticle lithium / nickel / cobalt oxide LiNi _0.6 Co _0.4 O ₂ was obtained.

Example 5

Layered structure nanoparticle lithium / nickel / cobalt oxide using the manufacturing method of the present invention (LiNi _0.5 Co _0.5 O ₂ Manufacturing

31.52g of lithium acetate (0.309 mol) of dihydrate _{(CH 3 CO 2 Li · 2H} 2 O), 38.10g (0.15 mol) of nickel acetate tetrahydrate, ((CH ₃ CO _{2) 2} Ni · 4H ₂ O) of And 38.13 g (0.15 mole) of cobalt acetate.4 hydrate ((CH ₃ CO ₂ ) ₂ Co.4H ₂ O) were placed together in an alumina crucible and self-mixed at 110 ° C. for 40 minutes. The melt is then calcined at 300 ° C. for 8 hours under precisely controlled atmosphere with carbon dioxide at 0.01 kgf / cm ² and sintered at 800 ° C. for 20 hours in air to obtain nanoparticulate lithium / nickel / cobalt oxide LiNi _0.5 Co _0.5 O ₂ was obtained.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make modifications without departing from the essential characteristics of the present invention. Therefore, the technical idea of the present invention is not limited to the above embodiment.

According to the economical manufacturing method of the crystalline nanoparticulate positive electrode active material for a high output lithium secondary battery using the self-mixing eutectic method according to the present invention, a complicated multi-step process with the conventional methods, high production cost due to the consumption of a lot of raw materials and energy, Since the shortcomings such as the necessity of expensive production equipment can be easily overcome, the process structure can be simplified and the production cost and production cost corresponding to these processes can be reduced. On the other hand, in the present invention, since the production of the material and the nano-atomization are completed in a single process at the same time, the production cost and the production period can be reduced, and thus the economic effect is great.

In addition, the layered nanoparticle lithium / nickel / cobalt oxide LiNi _1-x Co _x O ₂ (0.2 ≦ x ≦ 0.5) and the spinel structure nanoparticle lithium / manganese oxide LiMn ₂ O ₄ prepared according to the present invention are lithium 2 batteries. When used as a positive electrode active material, the nanoparticles having a large surface area not only increase the output of the lithium secondary battery, but also increase the efficiency and prolong the battery life.

Claims (7)

In order to ensure that the material synthesis and the nano-atomization process are achieved in a single integrated heat treatment process, the two or more metal compounds having a melting point between 25 and 200 ° C. and having a melting point in the range of 5 to 50 ° C. are weighed at an appropriate molar ratio. Step 1; A second step of obtaining a homogeneous fluid mixture by self-mixing eutectic at a temperature between 25-150 ° C .; Self-mixing eutectic method comprising the third step of calcination and sintering to produce a composite metal oxide while precisely controlling the mixture under a carbon dioxide atmosphere at a temperature between 200-900 ° C and a pressure of 0.001-5 kgf / cm 2. Method for producing a crystalline nanoparticles positive electrode active material for high power lithium secondary battery using. The method of claim 1, The metal compound, which is the initial reactant in the first step, is based on lithium acetate dihydrate, and is composed of manganese acetate tetrahydrate, nickel acetate tetrahydrate, cobalt acetate tetrahydrate, hydroxy aluminum acetate, iron acetate, and the like. A method for producing a crystalline nanoparticulate positive electrode active material for a high output lithium secondary battery using a self-mixing eutectic method, characterized in that at least one of iron acetylacetonate is selected. The method of claim 1, The composite metal oxide is formed of a composite metal oxide of lithium / manganese / metal (M) of the following formula: A method for producing a crystalline nanoparticle positive active material for a high output lithium secondary battery using a self-mixing eutectic method. LiMn _2-x M _x O ₄ (0 ≤ x ≤ 1) The method of claim 3, The metal (M) is a method for producing a crystalline nanoparticle positive active material for a high output lithium secondary battery using a self-mixing eutectic method, characterized in that selected from the group consisting of Ni, Co, Al and Fe. The method of claim 3, The composite metal oxide is formed of a lithium / manganese oxide of x = 0, wherein the mixing molar ratio of the lithium compound and the manganese compound is 1.03: 2.0 crystalline nano for high output lithium secondary battery using a self-mixing eutectic method Method for producing a particulate cathode active material. The method of claim 1, The composite metal oxide is formed of a composite metal oxide of lithium / nickel / metal (M) of the following formula: A method for producing a crystalline nanoparticulate positive electrode active material for a high output lithium secondary battery using a self-mixing eutectic method. LiNi _1-x M _x O ₂ (0 ≤ x ≤ 1) The method of claim 6, The metal (M) is selected from the group consisting of Co, Mn, Al and Fe, a method for producing a crystalline nanoparticles positive active material for high output lithium secondary battery using a self-mixing eutectic method.

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