KR102033113B1 - Metal composite, cathode active material comprising the same, secondary battery comprising the same and method for preparing the same - Google Patents

Abstract

The present invention provides a metal composite, a positive electrode active material using the same, a secondary battery using the same and a method for manufacturing the same, and through the present invention, such as pH instability, precipitation phase incompatibility, complex process, lack of reproducibility, particle growth The problem of the technology can be solved, and a metal complex having a continuous concentration gradient from the central portion of the particles to the surface portion can be produced.

Description

Metal composite, positive electrode active material including the same, secondary battery and manufacturing method thereof TECHNICAL COMPOSITE

The present invention relates to a metal complex, a cathode active material comprising the same, a secondary battery comprising the same, and a method for manufacturing the same. More specifically, a metal complex having a continuous metal concentration gradient, a cathode active material comprising the same, a secondary comprising the same A battery and a manufacturing method thereof.

Lithium secondary batteries have high energy density and are used as power devices for mobile phones and laptops. Portability of such devices is dependent on secondary batteries, which are key components, and thus research on high performance batteries has been continued. There are various characteristics required for the battery, such as charge and discharge characteristics, lifespan, high efficiency characteristics and stability at high temperatures.

Among lithium secondary batteries, 5 V class spinel cathode active material is the most popular cathode active material with high energy density due to high voltage.

Currently commercially available lithium _secondary batteries use LiCoO ₂ for the positive electrode and carbon for the negative electrode. LiCoO ₂ used in the positive electrode is a cobalt-based positive electrode active material, which is a typical cathode active material for lithium secondary batteries, has excellent life characteristics and conductivity characteristics, but has a disadvantage in that the capacity is small and the raw material is expensive. In order to solve this problem, studies on LiNiCoO ₂ cathode active materials have been actively conducted, but have not yet obtained satisfactory properties.

The most common method for producing a positive electrode active material is a solid phase reaction method, which is a method of repeatedly manufacturing a process of mixing and firing powders of carbonate or hydroxide of each component as a raw material. Disadvantages of this method include high impurity in the ball-mill process during mixing, uneven reaction, which makes it difficult to obtain a uniform phase, difficult to uniformly control the size of powder particles, high process temperature during manufacturing, and high production time. There are long points. In addition, as the charge and discharge cycle is repeated, the crystal structure of the active material is collapsed, and the lifetime characteristics of the electrons are also reduced.

In order to solve this problem, the co-precipitation method using chelate was developed, but there is a problem that exhaust gas such as NO _x or CO _x is emitted during firing, and also the precipitation region between metal composite materials such as Ni, Mn, Co and Al. Since they are different from each other, the growth of particles is slowed in the region of pH 11 to pH 13, which is the coprecipitation condition of a general metal complex oxide, and thus the production yield is reduced because particles of a desired size cannot be formed or the solution residence time in the reactor must be increased. Can cause problems.

Various methods have been developed to solve the above problems, but problems such as instability due to pH control, precipitation phase imbalance, difficulty in adding compounds other than metal cations, complex processes, lack of reproducibility in mass production, and growth retardation are solved. It's not yet mass production difficult.

It is an object of the present invention to provide a metal composite used in secondary batteries and cathode active materials and a manufacturing method thereof using a coprecipitation method, the metal composite manufacturing method of the present invention is a simple process, having a continuous concentration gradient, Metal composites having excellent effects can be produced.

Method for producing a metal complex for one purpose of the present invention is a first step of introducing a first metal salt solution to the reactor; A second step of introducing a second metal salt solution in which nanocolloid solutions of different concentrations are mixed into the reactor; A third step of preparing a mixed solution by mixing the first metal salt solution and the second metal salt solution in the reactor; A fourth step of adjusting the hydrogen ion concentration of the mixed solution to pH 10 or more in the reactor; And a fifth step of filtering, washing, and drying the mixed solution after the fourth step.

In one embodiment, the first metal salt solution may include at least one of nickel (Ni), manganese (Mn), and cobalt (Co).

In one embodiment, the second metal salt solution may include at least one of non-transition metal aluminum (Al), germanium (Ge), gallium (Ga), and indium (In).

In one embodiment, the metal salt concentration in the first metal salt solution may be 1.5 M to 2.5 M.

In one embodiment, the metal salt concentration in the second metal salt solution may be 0.01 M to 2.0 M.

In one embodiment, by adjusting the rate of injecting the first metal salt solution and the second metal salt solution into the reactor, it may be to adjust the molar ratio of the mixed solution in the reactor.

In one embodiment, the fourth step may be to use a sodium hydroxide solution and an aqueous ammonia solution.

Method for producing a metal composite for another object of the present invention is a first step of introducing a first metal salt solution containing nickel (Ni) and cobalt (Co) to the reactor; A second step of introducing a second metal salt solution containing aluminum (Al) into the reactor; A third step of preparing a mixed solution by mixing the first metal salt solution and the second metal salt solution in the reactor; A fourth step of adjusting the hydrogen ion concentration of the mixed solution to pH 10 or more in the reactor by using a sodium hydroxide solution and a concentrated aqueous ammonia solution; And a fifth step of filtering the mixed solution, washing with distilled water and drying at 120 ° C. after the fourth step.

In one embodiment, the first metal salt solution and the second metal salt solution may be injected at a constant rate to control the molar ratio of the mixed solution inside the reactor.

Method for producing a positive electrode active material for another object of the present invention comprises the steps of preparing a metal composite prepared by the method for producing a metal composite of the present invention; Preparing a mixture by mixing the metal complex having a continuous metal concentration gradient with a lithium salt; And calcining the mixture at a high temperature of 500 ° C. or higher for at least 5 hours.

Metal composites for still another object of the present invention is a metal complex represented by the following formula (1), the surface stability is increased through the gradient of the continuous concentration of the element from the central portion to the surface portion,

[Formula 1]

Ni _1-wxyz Co _w M1 _x M2 _y M3 _z (OH) _2-p X _p ,

M1, M2 and M3 of Formula 1 are each independently one of Al, Mg, Zr, Sn, Ca, Ge, Ga, wherein X is one of F, N, P, w is 0.01 to 0.2, X, y, and z are each 0 + 0.1 in x + y + z, and p is 0-0.1.

In one embodiment, the metal composite continuously decreases the concentration of nickel (Ni) and cobalt (Co) from the central portion to the surface portion, and at the same time, the concentrations of M1, M2, and M3 continuously increase from the central portion to the surface portion. Can be.

In one embodiment, the metal composite may have a particle size of 1 μm to 300 μm.

The cathode active material for another object of the present invention comprises the metal composite of the present invention and has a continuous metal concentration gradient from the particle center to the surface portion.

In one embodiment, the cathode active material may have a particle size of 1 μm to 30 μm.

In one embodiment, the positive electrode active material may have a surface area of 0.1 m ² / g to 2 m ² / g.

A secondary battery for still another object of the present invention includes the positive electrode active material of the present invention.

The present invention provides a metal composite, a positive electrode active material using the same, a secondary battery using the same and a method for manufacturing the same, and through the present invention, such as pH control instability, precipitation phase imbalance, complex process, lack of reproducibility, particle growth delay The problem of the technology can be solved, and a metal complex having a continuous concentration gradient from the central portion of the particles to the surface portion can be produced.

1 to 6 are views of the metal composite produced through an embodiment of the present invention.
7 to 9 are views for the positive electrode active material prepared through one embodiment of the present invention.
10 to 13 are views for a coin cell manufactured through an embodiment of the present invention.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprises" or "having" are intended to indicate that there is a feature, step, operation, component, part, or combination thereof described on the specification, and one or more other features or steps. It is to be understood that the present invention does not exclude, in advance, the possibility of the presence or the addition of an operation, a component, a part, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Method for producing a metal complex of the present invention comprises the first step of introducing a first metal salt solution into the reactor; A second step of introducing a second metal salt solution in which nanocolloid solutions of different concentrations are mixed into the reactor; A third step of preparing a mixed solution by mixing the first metal salt solution and the second metal salt solution in the reactor; A fourth step of adjusting the hydrogen ion concentration of the mixed solution to pH 10 or more in the reactor; And a fifth step of filtering, washing, and drying the mixed solution after the fourth step.

In one embodiment, the reactor may use a variety of reactors, including, but not limited to, a continuous reactor, for example, may use a CSTR continuous reactor. In one embodiment, the stirling speed of the reactor may be 300 RPM or more, but is not limited thereto, and may be 300 RPM to 700 RPM.

In one embodiment, the residence time of the mixed solution in the reactor may be 1 hour to 15 hours. In one embodiment, the reactor residence time may be to be added at a constant rate by adjusting the addition rate of each solution to 5 to 15 hours. For example, the residence time may be 10 hours, when the residence time is less than 5 hours, the overall productivity may decrease, and when it exceeds 15 hours, the problem that the formation of particles becomes difficult may occur.

In one embodiment, the reactor may contain distilled water, and the first metal salt solution may be introduced into the reactor containing distilled water. In the first metal salt solution and the second metal salt solution addition process of the first step and the second step, the first metal salt solution is first introduced for a predetermined time, and the second metal salt solution is added at the same time or the first metal salt solution is added. At the same time, the second metal salt solution may be added. Alternatively, the first metal salt solution and the second metal salt solution may be mixed and then added to the reactor.

In one embodiment, the first metal salt solution may include at least one of nickel (Ni), manganese (Mn), and cobalt (Co). For example nickel or nickel and cobalt. In addition, for example, it may be prepared using metal salts such as nickel sulfate (NiSO ₄ ), cobalt sulfate (CoSO ₄ ), nickel nitrate, and cobalt nitrate. For example, nickel and cobalt based hydroxides can be used.

In one embodiment, the second metal salt solution may include at least one of non-transition metal aluminum (Al), germanium (Ge), gallium (Ga), and indium (In). For example, the second metal salt solution is nickel (Ni), manganese (Mn), cobalt (Co), aluminum (Al), magnesium (Mg), zinc (Zn), tin (Sn), calcium (Ca), germanium It may include at least one of (Ge), gallium (Ga), indium (In). The second metal salt may be prepared using, for example, aluminum hydroxide (Al (OH) ₃ ), magnesium hydroxide, calcium sulfate, and the second metal salt solution may include a part of the first metal salt solution. have. When using an aluminum nitride (Al (NO) ₃ ) solution in the coprecipitation method, a problem may occur that the precipitation reaction is lowered and the growth is slowed.

In one embodiment, the concentration of the metal salt in the first metal salt solution may be 1.5 M to 2.5 M. For example, when the concentration of the metal salt is less than 1.5M may cause a problem that the overall yield is reduced, when the concentration of the metal salt exceeds 2.5M may cause a problem that the viscosity is high, the reactivity decreases.

In one embodiment, the metal salt concentration in the second metal salt solution may be 0.01 M to 2.0 M. For example, when the metal salt concentration is less than 0.01 M, the production rate may be low because the amount of metal added is too small as a whole, and when it exceeds 2.0 M, stable colloid formation may be difficult.

In one embodiment, the second metal salt solution may be a powder grinding solution prepared through a wet milling process, and the powder concentration in the powder grinding solution may be 0.01 wt% to 50.0 wt%.

In one embodiment the hydrogen ion concentration in the fourth step can be adjusted to pH 10 or more, for example, pH 10 to pH 12 can be adjusted.

Method for producing a metal complex of the present invention may be to adjust the molar ratio of the mixed solution in the reactor by controlling the rate of injecting the first metal salt solution and the second metal salt solution into the reactor. Alternatively, the molar ratio may be adjusted by adjusting the concentration of the first metal salt and the second metal salt solution. In the case of the second metal salt solution, the molar ratio may be adjusted by preparing nanocolloidal solutions having different concentrations, and mixing and adjusting the ratios.

In one embodiment, the fourth step may be to use a sodium hydroxide solution and an aqueous ammonia solution. The sodium hydroxide solution may be 1.0 wt% to 30.0 wt% sodium hydroxide solution, it can be added to the mixed solution to adjust the hydrogen ion concentration (pH), the reaction temperature is 50 ℃ to 70 ℃ by adding sodium hydroxide You can adjust it. The aqueous ammonia solution may be 5.0 wt% to 50.0 wt% aqueous ammonia solution, for example, 28.0 wt% aqueous ammonia solution. The component molar ratio of the mixed solution may be added at a constant rate so that the mixed solution is 0.5 to 2.0 empty based on ammonia.

Another method of manufacturing a metal complex of the present invention comprises the first step of injecting a first metal salt solution containing nickel (Ni) and cobalt (Co) to the reactor; A second step of introducing a second metal salt solution containing aluminum (Al) into the reactor; A third step of preparing a mixed solution by mixing the first metal salt solution and the second metal salt solution in the reactor; A fourth step of adjusting the hydrogen ion concentration of the mixed solution to pH 10 or more in the reactor by using a sodium hydroxide solution and a concentrated aqueous ammonia solution; And a fifth step of filtering the mixed solution, washing with distilled water and drying at 120 ° C. after the fourth step.

In one embodiment, the reactor may use various reactors, but is not limited thereto, and may be a continuous reactor, for example, a CSTR continuous reactor may be used. In one embodiment, the stirling speed of the reactor is not limited thereto, but may be 300 RPM or more, for example, 300 RPM to 700 RPM. In one embodiment, the residence time of the mixed solution in the reactor may be 1 hour to 15 hours. For example, it may be 10 hours, when the residence time is less than 1 hour, the overall productivity may be reduced, when more than 15 hours may cause problems that the particle formation becomes difficult.

In one embodiment, the reactor may contain distilled water, and the first metal salt solution may be introduced into the reactor containing distilled water. While the first metal salt solution is first added for a predetermined time, the second metal salt solution may be further added, and the first and second metal salt solutions may be simultaneously added together.

In one embodiment, the first metal salt solution may be prepared using metal salts such as, for example, nickel sulfate (NiSO ₄ ), cobalt sulfate (CoSO ₄ ), nickel hydroxide, cobalt hydroxide, and the like. Part of the first metal salt solution may be included, and may be prepared using aluminum hydroxide (Al (OH) ₃ ).

In one embodiment, the metal salt concentration in the first metal salt solution may be 1.5 M to 2.5 M. For example, when the concentration of the metal salt is less than 1.5M may cause a problem that the overall yield is reduced, and when it exceeds 2.5M may cause a problem that the viscosity is high, the reactivity is reduced. In one embodiment, the metal salt concentration in the second metal salt solution may be 0.01 M to 2.0 M. For example, when the metal salt concentration is less than 0.01 M, the amount of metal added as a whole is too small, the production rate and production efficiency may be lowered, and when it exceeds 2.0 M, stable colloid formation may be difficult.

The manufacturing method of the metal complex may be to adjust the molar ratio of the mixed solution in the reactor by controlling the rate of injecting the first metal salt solution and the second metal salt solution into the reactor. In one embodiment, the molar ratio of nickel, cobalt and aluminum in the mixed solution may be 0.8 to 1, 0 to 0.2, and 0 to 0.2. For example, the molar ratios of nickel, cobalt and aluminum can be 0.86, 0.12 and 0.02.

In one embodiment, the first metal salt solution and the second metal salt solution may be added at a constant rate to adjust the molar ratio of the mixed solution inside the reactor.

In one embodiment, the fourth step may be to use a sodium hydroxide solution and an aqueous ammonia solution. The sodium hydroxide solution may be 20 wt% sodium hydroxide solution, it can be added to the mixed solution to adjust the pH, the reaction temperature may be adjusted to 50 ℃ to 70 ℃. The aqueous ammonia solution may be 5 wt% to 50 wt% aqueous ammonia solution, for example 28% aqueous ammonia solution may be used. The ratio of ammonia and the mixed solution may be added at a constant rate such that the ratio of the mixed solution is 0.5 to 2.0 based on ammonia.

For example, the method of manufacturing a metal complex of the present invention comprises adding a first metal salt solution containing nickel and cobalt as a main metal salt into a reactor containing distilled water and simultaneously adding aluminum, manganese, zinc, Through a wet milling process of a powder containing at least one element (eg, 1 to 3) selected from hydroxides, oxides, nitrogen compounds, fluorine compounds and phosphoric acid compounds in which tin, calcium, germanium, and gallium are combined with cations Two powder grinding solutions (nano colloidal solutions) having different concentrations were prepared, and the mixing ratios of the powder grinding solution for forming the center portion and the powder grinding solution for forming the surface portion were 100 wt%: 0 wt% to 0 wt%: 100 wt By mixing the solutions so that they can vary gradually by%, the concentrations of M1, M2 and M3 will have a continuous concentration gradient from the center to the surface. Adding the sodium hydroxide solution and the aqueous ammonia solution into the reactor so as to adjust the hydrogen ion concentration of the entire first metal salt solution added to the reactor to pH 10 or more, for example, pH 10 to pH 12 It is possible to precipitate the metal composite (nickel composite hydroxide precursor) particles represented by Formula 1 below.

[Formula 1]

Ni _1-wxyz Co _w M1 _x M2 _y M3 _z (OH) _2-p X _p ,

M1, M2 and M3 of Formula 1 are each independently one of Al, Mg, Zr, Sn, Ca, Ge, Ga, wherein X is one of F, N, P, w is 0.01 to 0.2, X, y, and z are each 0 + 0.1 in x + y + z, and p is 0-0.1.

Method for producing a cathode active material of the present invention comprises the steps of preparing a mixture by mixing a metal complex having a continuous metal concentration gradient, prepared by the method for producing a metal complex of the present invention with lithium salt; And calcining the mixture at a high temperature of 500 ° C. or higher for at least 5 hours.

The lithium salt is not limited thereto, for example, lithium hydroxide (LiOH) may be used, and the molar ratio of lithium to the metal complex of the mixture may be 0.8 to 1.5 based on the metal complex. . For example, the molar ratio of lithium based on the metal complex may be 1.05.

In one embodiment, the high temperature of 500 ° C. or higher may be 600 ° C. to 900 ° C., for example, 730 ° C.

In one embodiment, the firing step may be performed for 5 hours to 30 hours, for example, 10 hours, and in one embodiment, the firing step may be performed in an air atmosphere or an oxygen atmosphere.

The metal complex of the present invention is a metal complex represented by the following formula 1, the surface stability is increased through the continuous concentration gradient of the element from the central portion to the surface portion,

[Formula 1]

Ni _1-wxyz Co _w M1 _x M2 _y M3 _z (OH) _2-p X _p ,

M1, M2 and M3 of Formula 1 may be each independently one from Al, Mg, Zr, Sn, Ca, Ge and Ga, etc., X may be one from F, N, P, etc., wherein w is 0.01 to 0.2, x, y and z may be 0 + 0.1 x + y + z, p may be 0 to 0.1.

The metal complex may increase stability through surface stabilization by a continuous concentration gradient of the metal element from the central portion to the surface portion. Therefore, excellent reproducibility and mass productivity can be obtained, and through this, the stability and performance of the cathode material can be improved.

Characterized in that the concentration of nickel (Ni) and cobalt (Co) continuously decreases from the central portion to the surface portion,

In one embodiment, the metal complex may continuously decrease the concentration of nickel (Ni) and cobalt (Co) from the center to the surface portion, and at the same time, the concentrations of M1, M2, and M3 may continuously increase from the center portion to the surface portion. have.

In one embodiment, the metal composite may have a particle size of 1 μm to 300 μm.

The positive electrode active material for another object of the present invention may have a continuous metal concentration gradient from the particle center to the surface portion.

In one embodiment, the positive electrode active material including the metal composite continuously decreases the concentration of nickel (Ni) and cobalt (Co) from the central portion to the surface portion, and the concentrations of M1, M2, and M3 increase from the central portion to the surface portion. It may be increasing continuously.

The metal complex may be one in which the concentration of nickel and cobalt gradually decreases from the center portion to the surface portion, and the concentration of aluminum and the like may gradually increase from the center portion to the surface portion.

In one embodiment, the surface area of the cathode active material may be 0.1 m ² / g to 2.0 m ² / g, the particle size may be 1 μm to 30 μm. For example, the particle size of the cathode active material may be 9 μm.

The secondary battery of the present invention may include the cathode active material of the present invention.

The present invention relates to a lithium secondary battery (Li-ion battery) nickel-containing metal complex (or metal complex oxide), a positive electrode active material comprising the same and a method for manufacturing the same, for a lithium secondary battery using co-precipitation (co-precipitation) In the production of a multi-component metal oxide-based cathode active material having a high nickel content, a solution containing a nickel metal expressing a main capacity and a metal hydroxide solution prepared by wet milling to improve the cathode material characteristics By stably injecting to have a continuous concentration gradient by using, it is a technique for a positive electrode material having the effect of improving the size of particles, increase the average density, improve the characteristics of the cathode than the conventional coprecipitation method.

The present invention can facilitate the preparation of a nickel-containing multi-component metal composite (or metal oxide-based) high capacity positive electrode active material for lithium secondary batteries using a coprecipitation method, can make the average particle size uniform, and reduce the fine powder to improve cathode material performance. Can be improved.

The conventional coprecipitation method is a method of forming a stable nano-colloidal particles containing only one multi-component coprecipitation solution or containing aluminum, such as by adjusting the pH, or a method having no concentration gradient.

The present invention is wet preparation of a solid sample (powder) of a component containing various functional cations / anions to improve the function of the positive electrode material simultaneously with the input of one main metal salt solution (for example, the first metal salt solution). The process forms two or more solutions of different concentrations (e.g., nanocolloid solutions of different concentrations, one for forming the core and the other for forming the surface), and in a proportion Thus, the nickel-containing metal for a lithium secondary battery capable of improving the disadvantages of the conventional separation administration method and stably injecting various functional components to have a selective and continuous concentration gradient, thus enabling high capacity / high performance expression. Complexes may be provided.

In the method of preparing a metal complex, a second metal salt solution prepared by wet grinding of a powder of a first metal salt solution including a metal salt having a similar precipitation region such as nickel, manganese, cobalt, and aluminum, and the like is added to a reactor. Thereby, the fine powder is effectively removed, and the concentration of nickel and cobalt in the produced particles decreases with a continuous concentration gradient from the particle center of the metal complex to the surface portion, and the concentration of M1 to M3 decreases from the center to the surface. It is characterized by increasing with a continuous concentration gradient toward the wealth, and has the effect of effectively distributing various functional components regardless of the precipitation area, which is an advantage of the coprecipitation method using the conventional powder grinding solution, stability of the performance of the cathode material Can be increased.

For various metals, there was a difficulty in mass production because of the problem that the separate dose solution affects the formation of initial parent particles (ie, metal complexes). In the present invention, in order to solve this problem, it is possible to prepare a first metal salt solution containing a metal salt having a similar precipitation region, such as Ni, Mn, Co, and wet the metal salt having a different precipitation hydrogen ion concentration (pH) region, such as Al The powder grinding solution prepared through the milling process may be prepared as a second metal salt solution. After the first metal salt solution is added and a predetermined time elapses, separate administration may be performed at a predetermined ratio. By the separate administration, an appropriate spherical precursor having a concentration gradient from the center portion to the surface portion, that is, a metal complex may be formed, and the concentration of various secondary metals such as Al, which increases on the surface portion, increases the stability of the cathode material. Has the effect of

Hereinafter, embodiments of the present invention will be described in detail. However, the following examples are only some embodiments of the present invention, and the present invention should not be construed as being limited to the following examples.

Example 1 (metal complex production)

The first metal salt solution was prepared using metal salts NiSO ₄ and CoSO ₄ such that the Ni / Co molar ratio was 0.88 / 0.12. As a second metal salt solution separated therefrom, Al (OH) ₃ powder was wet-milled to prepare a nanocolloid solution (powder milling solution) containing nano-sized particles. The nanocolloid solution was prepared by mixing the nano-colloid solution for forming the center and the nano-colloid solution for forming the surface portion of different concentrations, respectively.

Of the two metal salt solutions, the first metal salt solution was first introduced into a CSTR continuous reactor. Between 3 hours and 6 hours after the addition, the second metal salt solution was added to the reactor to prepare a mixed solution. At this time, the nano-colloid solution for forming the center and the nano-colloid solution for forming the surface portion were added while mixing at a constant ratio, by adjusting the feed rate of the first metal salt solution and the second metal salt solution, Ni / of the mixed solution in the reactor Co / Al molar ratio was set to 0.86 / 0.12 / 0.02. At the same time a 20 wt% sodium hydroxide (NaOH) solution and concentrated aqueous ammonia solution were added. The amount of the sodium hydroxide solution was adjusted so that the hydrogen ion concentration of the mixed solution was pH 10 to pH 12. The stiring speed of the reactor was adjusted to 300 RPM to 700 RPM, and the dosage was adjusted so that the residence time of the total solution was about 10 hours.

Thereafter, the solution was collected in a CSTR continuous reactor, filtered, washed with distilled water, and dried in an oven at 120 ° C. to prepare a metal complex (nickel complex hydroxide) (metal complex 1). The metal complex may be a precursor of a cathode active material.

Example 2 (metal composite production)

The first metal salt solution was prepared using metal salts NiSO ₄ and CoSO ₄ such that the Ni / Co molar ratio was 0.88 / 0.12. As a second metal salt solution separated from this, Al (OH) ₃ powder was wet milled to prepare a nanocolloid solution including nano-sized particles.

 Of the two metal salt solutions, the first metal salt solution was first introduced into a CSTR continuous reactor. Six hours after the addition, the second metal salt solution was added to the reactor to prepare a mixed solution. At this time, each solution was added while mixing at a constant ratio. The feed rate of the first metal salt solution and the second metal salt solution was adjusted so that the molar ratio of Ni / Co / Al in the mixed solution was 0.86 / 0.12 / 0.02 in the reactor. Simultaneously, 20 wt% sodium hydroxide solution and concentrated aqueous ammonia solution were administered. The amount of the sodium hydroxide solution was adjusted so that the hydrogen ion concentration of the mixed solution was pH 10 to pH 12. In addition, the stirring speed of the reactor was adjusted to 300 RPM to 700 RPM, and the dose was adjusted so that the residence time of the total solution was about 10 hours.

Thereafter, the solution was collected in a CSTR continuous reactor, filtered, and then sufficiently washed with distilled water and dried in an oven at 120 ° C. to prepare a metal composite (metal composite 2). The metal complex may be used as a precursor of the positive electrode active material.

Example 3 (Comparative Example 1)

The first metal salt solution was prepared using metal salts NiSO ₄ and CoSO ₄ , the second metal salt solution (powder milling solution) was prepared using Al (OH) ₃ , and the two solutions were simultaneously added to a CSTR continuous reactor. Mixed solution was prepared. The feed rate of the two solutions was adjusted so that the Ni / Co / Al molar ratio of the mixed solution was 0.86 / 0.12 / 0.02. At the same time, 20 wt% sodium hydroxide solution and concentrated ammonia solution were added to the mixed solution. At this time, the dose of the sodium hydroxide solution was adjusted so that the hydrogen ion concentration of the mixed solution in the reactor was pH 11 to pH 13. The stiring speed of the reactor was adjusted to 300 RPM to 700 RPM, and the dosage was adjusted so that the residence time of the total solution was about 10 hours.

Thereafter, the solution was received in a CSTR continuous reactor, filtered, and then sufficiently washed with distilled water and dried in an oven at 120 ° C. to prepare a metal composite (metal composite 3). The metal complex may be a precursor of a cathode active material.

Example 4 (Preparation of Anode Active Material)

The metal complexes prepared through Examples 1, 2 and Comparative Example 1 were mixed using LiOH as a lithium salt, so that the molar ratio of Li to the metal complex was 1.05 / 1.0, and the mixture was 730 ° C. in an oxygen atmosphere. The reaction was carried out for 10 hours to 20 hours.

Example 5 (Preparation Example 1: Preparation of a cathode active material lithium ion battery)

Each of the three cathode active materials prepared in Example 4, PVDF (Polyvinylidene Fluoride) as a binder, and denca black (commercial name: super p) as a conductive material were mixed in a ratio of 94: 3: 3. After mixing, it was coated with an aluminum current collector, then dried and roll pressed to prepare a coin cell using an electrode prepared. At this time, 1M LiPF ₆ EC / EMC (1: 2) was used as the electrolyte.

result

1 is a view of a metal composite prepared through an embodiment of the present invention. Referring to FIG. 1, the metal composite of the present invention is simply illustrated as a figure, and the concentration of aluminum increases from the center of the metal composite to the surface portion.

2 to 6 are views of the metal composite prepared through one embodiment of the present invention. Specifically, FIGS. 2 to 4 show the metal composite particles prepared in Examples 1, 2 and 3 (Comparative Example 1) of the present invention, respectively, using a scanning electron microscope (SEM). The size and distribution of the particles are shown. 2 to 4, it can be confirmed that the metal complex having a size of about 1 μm to 20 μm, more uniformly in the case of particles produced through Examples 1 and 2 of the present invention than when manufactured through a comparative example. It can be seen that the particles are formed, it can be seen that the particles are formed evenly.

Specifically, FIGS. 5 and 6 show the results of component analysis of the cross-sections of the metal composites prepared in Examples 1 and 2 according to the present invention through an Electron Probe Micro-Analyzer (EPMA). . As shown in FIGS. 2 and 3, the metal composite particles prepared in Examples 1 and 2 look similar when compared to only SEM images, but in FIGS. 5 and 6, the metal composites shown in Example 1 are shown. It can be seen that aluminum is present from the center more than the metal complex 2 shown in Example 1 of Example 2.

7 to 9 are views for the positive electrode active material prepared through an embodiment of the present invention. Specifically, a scanning electron microscope image of a cathode active material prepared using a metal composite prepared according to an embodiment of the present invention. Referring to FIGS. 7 to 9, each cathode active material has an average particle diameter of 9 μm or more. It can be seen that the fine amount decreases.

10 to 13 are views for a coin cell manufactured through an embodiment of the present invention. Specifically, FIG. 9 to FIG. 13 show initial charge / discharge curves of the coin cell manufactured in Example 5, and charging was performed under a condition of 1/20 C in a 4.3 V constant current / constant voltage method.

Referring to Table 1 below, for the cathode material prepared in Example 1, the initial efficiency was about 92%, the reversible charge and discharge capacity was confirmed to be about 208 mAh / g at 0.1 C-rate, the speed of 4 C It can be seen that the excellent speed characteristics of 71.2% compared to the speed of 0.1 C. The cycle test also showed excellent stability of 96.7% at the 50th cycle, which was confirmed to be superior to Example 2 and Comparative Example 1.

division C-rate Charge and discharge capacity
(mAh / g) Coulomb Efficiency
(%) Rate efficiency (%)
(4C vs. 0.1C) Cycle efficiency (%)
(50 ^th vs. 1 ^st ) Example 1
Cathode material 0.1C / 0.1C 219/202 92.2 71.2 96.7 0.5C / 0.1C 198/208 105.1 0.5C / 0.2C 202/199 98.5 0.5C / 0.5C 196/190 96.9 0.5C / 1.0C 188/183 97.3 0.5C / 2.0C 182/174 95.6 0.5C / 4.0C 173/148 85.5 Example 2
Cathode material 0.1C / 0.1C 225/195 86.7 74.1 92.6 0.5C / 0.1C 196/201 102.6 0.5C / 0.2C 202/196 97.0 0.5C / 0.5C 196/188 95.9 0.5C / 1.0C 189/182 96.3 0.5C / 2.0C 182/169 92.9 0.5C / 4.0C 170/149 87.6 Comparative Example 1
Cathode material 0.1C / 0.1C 207/176 85.0 77.3 68.5 0.5C / 0.1C 175/172 98.3 0.5C / 0.2C 171/163 95.3 0.5C / 0.5C 163/155 95.1 0.5C / 1.0C 156/150 96.2 0.5C / 2.0C 151/144 95.4 0.5C / 4.0C 145/133 91.7

Although the above has been described with reference to the accompanying drawings and preferred embodiments of the present invention, those skilled in the art can variously change the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. It will be appreciated that modifications and variations can be made.

Claims (17)

As a method for producing a metal complex,
A first step of introducing a first metal salt solution into the reactor;
A second step of introducing a second metal salt solution in which two nanocolloid solutions having different concentrations are mixed into the reactor;
A third step of preparing a mixed solution by mixing the first metal salt solution and the second metal salt solution in the reactor;
A fourth step of adjusting the hydrogen ion concentration of the mixed solution to pH 10 or more in the reactor; And
After the fourth step, the fifth step of filtering, washing and drying the mixed solution;
The first metal salt solution includes at least one of nickel (Ni), manganese (Mn) and cobalt (Co),
The second metal salt solution includes at least one or more of aluminum (Al), germanium (Ge), gallium (Ga), and indium (In), and the two nanocolloidal solutions are a solution for forming a core and a solution for forming a surface portion. The two nanocolloid solutions are mixed so that the mixing ratio of the solution for forming the center and the solution for forming the surface portion varies from 100 wt%: 0 wt% to 0 wt%: 100 wt% from the center portion of the metal composite to the surface portion. Wherein the concentration of the element of the second metal salt solution has a continuous concentration gradient from the central portion to the surface portion,
Method for producing a metal complex.
delete delete The method of claim 1,
Metal salt concentration in the first metal salt solution, characterized in that 1.5 to 2.5 M,
Method for producing a metal complex.
The method of claim 1,
Metal salt concentration in the second metal salt solution, characterized in that 0.01 to 2.0 M,
Method for producing a metal complex.
The method of claim 1,
By adjusting the rate of injecting the first metal salt solution and the second metal salt solution into the reactor, it characterized in that for controlling the molar ratio of the mixed solution in the reactor,
Method for producing a metal complex.
The method of claim 1,
The fourth step is characterized by using a sodium hydroxide solution and an aqueous ammonia solution,
Method for producing a metal complex.
As a method for producing a metal complex,
A first step of introducing a first metal salt solution containing nickel (Ni) and cobalt (Co) into the reactor;
A second step of injecting a second metal salt solution including aluminum (Al) into the reactor and mixing two nanocolloid solutions having different concentrations;
A third step of preparing a mixed solution by mixing the first metal salt solution and the second metal salt solution in the reactor;
A fourth step of adjusting the hydrogen ion concentration of the mixed solution to pH 10 to pH 12 in the reactor by using sodium hydroxide solution and concentrated aqueous ammonia solution; And
After the fourth step, the mixed solution is filtered, and includes a fifth step of washing with distilled water and drying at 120 ° C.,
The two nanocolloidal solutions are divided into a center forming solution and a surface forming solution, and the mixing ratio of the central forming solution and the surface forming solution from the center of the metal complex to the surface is 100wt%: 0wt%. 0wt%: The two nanocolloid solutions are mixed so as to change up to 100wt%, and the concentration of Al has a continuous concentration gradient from the center portion to the surface portion.
Method for producing a metal complex.
The method of claim 8,
Injecting the first metal salt solution and the second metal salt solution at a constant rate to adjust the molar ratio of the mixed solution inside the reactor,
Method for producing a metal complex.
Preparing a metal composite prepared by the method of any one of claims 1, 4 to 9;
Preparing a mixture by mixing the metal complex having a continuous metal concentration gradient with a lithium salt; And
Comprising calcining the mixture at a high temperature of 500 ° C. or higher for at least 5 hours.
Method for producing a cathode active material. delete delete delete delete delete delete delete

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