KR20170090556A - Metal Composite Oxide, Method For Preparing The Same And Method For Measuring Concentration Of Sulfate In Manufacturing Process The Same - Google Patents

Abstract

The present invention relates to a composite metal oxide, a production method thereof, and a method for measuring concentration of sulphate in the production for the same. According to the present invention, in the production of metal oxide-based positive electrode active materials for lithium secondary batteries, it is possible to improve functionality of positive electrode materials by measuring content of sulphate in precursor powder of composite metal hydroxide, thereby enabling easy production of composite metal oxide for lithium secondary batteries ensuring high capacity and high performance.

Description

TECHNICAL FIELD The present invention relates to metal complex oxides, metal complex oxides, metal complex oxides, metal complex oxides, metal complex oxides,

Metal composite oxide, a method for producing the same, and a method for measuring a sulfate concentration in the production process.

The lithium secondary battery has a high energy density and 1.5 to 2 times higher energy density than the Ni / Cd battery in terms of the same volume, so that it has become popular as a power source for mobile phones and notebook computers.

Particularly, the performance of these products depends on the performance of the secondary battery, which is a core component, and thus the demand for a high performance battery is very large. Characteristics required for the battery include various aspects such as charge / discharge characteristics, lifetime, high rate characteristics, and stability at high temperatures.

Among the lithium secondary batteries, the 5V spinel cathode active material is a cathode active material having a high energy density due to high voltage.

A LiCoO ₂ in the positive electrode that lithium is now commercially available battery, the negative electrode, the I'm using carbon, small and thus representative for a lithium secondary battery positive electrode active material of a cobalt-based positive electrode active material LiCoO ₂ has an excellent life characteristic, and the conductivity, but the capacity material There is a drawback that it is expensive.

In order to solve this problem, studies on LiNiCoO ₂ cathode active material in which a portion of LiNiO ₂ has been substituted with cobalt have been actively studied. However, since the high-rate charge-discharge characteristics and high-temperature characteristics have not yet been satisfactorily satisfied, It is true.

On the other hand, the most common method of producing the cathode active material is a solid-phase reaction method. The solid-phase reaction method is repeatedly carried out by repeatedly mixing and firing powders of carbonates or hydroxides of each constituent element as raw materials.

However, the disadvantage of the solid-phase reaction method is that a large amount of impurities are introduced from the ball mill and the heterogeneous reaction tends to occur during mixing, so that it is difficult to obtain a uniform phase, and it is difficult to control the size of the powder particles uniformly, Is high and the manufacturing time is long. Further, as the charge and discharge cycles are repeated, there is a problem that the crystal structure of the active material collapses and the lifetime characteristics of the battery also deteriorate.

In order to solve this problem, a coprecipitation method using a chelate has been disclosed, but this method has a problem that exhaust gas such as NO _x or CO _x is exhausted during firing, and since a sulfate solution is used as the FEED solution, Sulfate remains and remains impurities in the precursor even after the filtering and drying processes, making it difficult to manufacture the cathode active material for a lithium secondary battery.

 Therefore, there is a need to study a method for preparing a metal composite oxide for a lithium secondary battery capable of exhibiting a high capacity / high performance by improving the function of a cathode material by estimating the sulfate content in the metal complex hydroxide precursor powder by measuring the sulfate content in the production of the cathode active material to be.

Japanese Laid-Open Patent No. 2012-142154.

An object of the present invention is to provide a method for preparing a metal oxide-based cathode active material for a lithium secondary battery, which comprises measuring the concentration of a sulfate in a reactor when preparing a metal complex hydroxide solution and estimating the sulfate content in the metal complex hydroxide precursor powder to improve the function of the anode material And a method for producing a metal complex oxide for a lithium secondary battery capable of exhibiting high capacity / high performance.

According to an aspect of the present invention,

Injecting a primary metal salt solution containing nickel (Ni) and cobalt (Co) as a first metal salt into a reactor containing distilled water;

A secondary metal salt solution containing at least one selected from Al, Mn, Mg, Sr, Ca, Ge, Ga, In and Sb as a second metal salt is injected into the reactor simultaneously with the injection of the primary metal salt solution step;

Injecting a sodium hydroxide (NaOH) solution and an aqueous ammonia solution into the reactor to produce a metal complex hydroxide solution;

Measuring a Raman spectrum of the metal complex hydroxide solution by Raman spectroscopy;

Preparing a solution of Ni, Co sulfate solution having five concentrations of 0.01, 0.1, 0.5, 1 and 2 M, and measuring Raman spectrum by Raman spectroscopic analysis of each solution; And

And measuring the sulfate concentration of the metal complex hydroxide solution by comparing the respective Raman spectra of the Raman spectrum of the metal complex hydroxide solution with the five concentrations of the Ni and Co sulfate solution.

The present invention relates to a process for producing a metal oxide-based cathode active material for a lithium secondary battery, which comprises predicting a sulfate content in a metal complex hydroxide precursor powder to improve the function of the cathode material and to provide a metal complex oxide for a lithium secondary battery capable of high capacity / .

1 is a graph showing the results of Raman spectroscopic analysis of the metal complex hydroxide solution according to Example 1 according to the reaction time.
2 is a graph showing the results of Raman spectroscopic analysis of the metal complex hydroxide solution according to Example 2 according to the reaction time.
FIG. 3 is a graph showing the results of Raman spectroscopic analysis according to five concentrations of a NiCoSO ₄ solution. FIG.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various elements, but the elements should not be limited by terms. Terms are used only for the purpose of distinguishing one component from another.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise.

In the present invention, the terms "comprising" or "having ", and the like, specify that the presence of a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Therefore, the configurations shown in the embodiments described herein are merely the most preferred embodiments of the present invention and are not intended to represent all of the technical ideas of the present invention. Therefore, various equivalents And variations.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

Hereinafter, a method for producing a metal composite oxide according to the present invention will be described in detail.

The present invention relates to a method for in situ measurement of the concentration of sulfate in a reactor according to the reaction time in the preparation of a metal complex hydroxide solution for a lithium secondary battery using a continuous coprecipitation synthesis method. Specifically, the method for preparing a metal composite oxide according to the present invention can estimate the sulfate content in the metal complex hydroxide precursor powder by measuring the concentration of sulfate in the metal complex hydroxide solution using Raman spectroscopy, thereby improving the function of the cathode material It is useful.

In the method for producing a metal composite oxide according to the present invention,

Injecting a primary metal salt solution containing nickel (Ni) and cobalt (Co) as a first metal salt into a reactor containing distilled water;

A secondary metal salt solution containing at least one selected from Al, Mn, Mg, Sr, Ca, Ge, Ga, In and Sb as a second metal salt is injected into the reactor simultaneously with the injection of the primary metal salt solution step;

Injecting a sodium hydroxide (NaOH) solution and an aqueous ammonia solution into the reactor to produce a metal complex hydroxide solution;

Measuring a Raman spectrum of the metal complex hydroxide solution by Raman spectroscopy;

Preparing a solution of Ni, Co sulfate solution having five concentrations of 0.01, 0.1, 0.5, 1 and 2 M, and measuring Raman spectrum by Raman spectroscopic analysis of each solution; And

(SO ₄ ^{2 -} ) concentration of the metal complex hydroxide solution by comparing the respective Raman spectra according to the five concentrations of the Raman spectrum of the metal complex hydroxide solution and the Ni and Co sulfate solution.

As one example, two or more metal salt solutions may be used in the present invention, and the hydrogen ion concentration (pH) of each solution may be adjusted.

To this end, the primary metal salt solution contains nickel (Ni) and cobalt (Co) metal salts having similar optimum precipitate hydrogen ion concentration (pH) characteristics, and the second metal salt solution contains Al , Mn, Mg, Sr, Ca, Ge, Ga, In and Sb.

Next, the secondary metal salt solution is prepared at a hydrogen ion concentration (pH) condition to form stable nano-sized colloid particles, thereby accelerating the growth of the precursor particles or controlling the growth of the precursor particles, To the effect of adjusting.

These effects reduce the amount of precursor particles and increase product yield.

As an example, in the step of injecting a secondary metal salt solution into the reactor, the secondary metal salt solution may be in a nano-sized colloidal state with a hydrogen ion concentration (pH) of 6 to 12 conditions. In this case, since the control of the hydrogen ion concentration (pH) of the secondary metal salt solution is involved in the particle growth in the reactor, the size of the metal complex oxide particle can be easily controlled by controlling the hydrogen ion concentration (pH) .

As one example, in the step of preparing the metal complex hydroxide solution, the hydrogen ion concentration (pH) of the metal complex hydroxide may be 11 to 13.

As one example, the nickel complex hydroxide precursor particles of the metal complex hydroxide solution may be represented by the following general formula (1).

[Chemical Formula 1]

Ni _{1 -wxy- z} Co _m M1 _x M 2 _y M 3 _z (OH) ₂

W, x, y and z are selected from the group consisting of Al, Mn, Mg, Sr, Ca, Ge, Ga, In and Sb, x + y + z? 0.1.

As an example, measuring the Raman spectrum of the metal complex hydroxide solution by Raman spectroscopy may include:

Precipitating the nickel complex hydroxide precursor particles from the metal complex hydroxide solution and separating the nickel complex hydroxide precursor particles into a precipitate and a supernatant; And

Transferring the supernatant to a container, and performing Raman spectroscopic analysis on the supernatant.

Specifically, the step of separating the precipitate and the supernatant liquid comprises separating the precipitated metal complex hydroxide into a precipitate and a supernatant by receiving the solution in which the metal complex hydroxide solution overflows over the reaction time in the CSTR continuous reactor . In addition, the step of performing Raman spectroscopic analysis on the supernatant is performed by transferring the supernatant to another vessel, measuring the intensity of the main peak (v1, frequency 980 cm ^-1 ) of the sulfate in the supernatant and measuring the Raman spectrum .

As another example, the step of measuring the Raman spectrum of the metal complex hydroxide solution by Raman spectroscopic analysis may include the step of performing Raman spectroscopic analysis while circulating the metal complex hydroxide solution. A method of circulating the solution can be performed by ultrasonic treatment through an ultrasonic generator and circulating the solution through the tube.

Specifically, in the CSTR continuous reactor, the metal complex hydroxide solution receives the overflow solution according to the reaction time, and the precipitate solution is subjected to the ultrasonic treatment through the sonicator, and the thin glass is connected by the metering pump A method of circulating the solution by connecting a silicone tube (Laboratory Made.) Can be performed. The Raman spectrum can be measured by measuring the intensity of the main peak (v1, frequency: 980 cm ^-1 ) of the sulfate while circulating the solution in the above manner.

The Ni / Co sulphate solution was prepared so as to have five concentrations of 0.01, 0.1, 0.5, 1 and 2 M as a solution for comparing the Raman spectrum of the sulfate of the metal complex hydroxide solution to predict the sulfate concentration, , The step of measuring the Raman spectrum by Raman spectroscopic analysis may include the step of measuring the intensity of the main peak (v1, frequency: 980 cm ^-1 ) of the sulfate to measure the Raman spectrum.

As one example, the method for producing a metal composite oxide according to the present invention is characterized in that Raman spectrum of the metal complex hydroxide solution is compared with Raman spectrum according to various concentrations of Ni and Co sulfate solution, SO ₄ ^{2 -)} may include the step of predicting the concentration. At this time, the five concentrations of the Ni, Co sulfate solution may be 0.01, 0.1, 0.5, 1 and 2 M, and a solution having a higher concentration can be further prepared.

In this way, the present invention can easily measure the sulfate concentration in the reactor according to the reaction time in the preparation of the metal complex hydroxide solution.

As one example, the primary metal salt solution may contain 1.923 to 3 mol% of the second metal salt.

In one embodiment, the first metal salt concentration in the first metal salt solution is 0.001 to 3 M, and the residence time in the reactor is 5 to 50 hours. At this time, when the concentration of the first metal salt is within the above range, the overall yield is prevented from being lowered, and viscosity and reactivity can be prevented from being lowered.

As one example, the concentration of the second metal salt in the second metal salt solution may be 0.01 to 2 M, and the residence time in the reactor may be 5 to 50 hours. At this time, when the concentration of the second metal salt is in the above range, the production rate is increased and it is easy to form a stable colloid.

When the primary metal salt solution and the secondary metal salt solution are injected, if the particle retention time is less than 5 hours, the overall productivity is lowered. If the particle retention time is longer than 50 hours, the formation of particles may become difficult. It is preferable to comply with the concentration and time conditions set forth in the present invention.

In the case of the secondary metal salt solution according to the present invention, nano-sized colloid is smoothly formed when the pH is 6 to 12, and excessive precipitation is prevented, thereby preventing excessive growth of aluminum particles .

As an example, the sodium hydroxide solution according to the present invention may be adjusted to have a concentration of 1 to 30 wt% and a reaction temperature of 30 to 80 ° C by adding the sodium hydroxide solution.

 As one example, the aqueous ammonia solution according to the present invention is used at a concentration of 5 to 50 wt%, and is injected at a constant rate such that the molar ratio of ammonia to first metal salt + second metal salt is 1: 1 to 1: 4 .

As one example, the nickel complex hydroxide precursor particle size according to the present invention can be adjusted to 1 to 30 탆.

Hereinafter, a cathode active material for a lithium secondary battery according to the present invention will be described.

The cathode active material according to the present invention is prepared by mixing the nickel complex hydroxide precursor particles produced by the above-mentioned method for preparing a metal composite oxide with a lithium salt in a molar ratio of 0.8 to 1.5, and heating the mixture at a temperature of 600 to 900 캜, To < RTI ID = 0.0 > 30 hours. ≪ / RTI >

Specifically, the cathode active material according to the present invention is prepared by mixing the nickel complex hydroxide at a ratio of lithium compound to lithium to metal of 1 to 1.2 molar ratio and pre-treating it at 400 to 600 ° C. in an atmospheric or oxygen atmosphere, Followed by heat treatment at 900 ° C in an air atmosphere or an oxygen atmosphere.

As an example, the cathode active material according to the present invention may have a particle size of 1 to 30 μm, more specifically an average particle diameter of 5 to 20 μm, and a surface area of 0.1 to 2 m ² / g.

When the average particle diameter of the cathode active material is in the above range, the formation of impurities on the surface can be minimized and the increase in the distance of diffusion of lithium ions into the particles can be prevented, thereby preventing the rate characteristic from being deteriorated.

In addition, the present invention provides a lithium secondary battery including the above cathode active material.

Best Mode for Carrying Out the Invention Hereinafter, the present invention will be described in more detail with reference to examples and drawings based on the above description. The following examples are intended to illustrate the invention and are not intended to limit the scope of the invention.

Example  One

The primary metal salt solution was prepared by using NiSO ₄ and CoSO ₄ metal salts so that the molar ratio of Ni / Co was 0.86 / 0.15, and Al (NO ₃ ) ₃ solution was prepared as a separated secondary metal salt solution. In the case of Al (NO ₃ ) ₃ solution, a proper amount of 1 M sodium hydroxide (NaOH) solution or concentrated ammonia solution was administered to adjust the hydrogen ion concentration (pH) between 6 and 12. These two solutions were simultaneously administered to a CSTR continuous reactor. The rate of application of the two solutions was controlled so that the molar ratio of Ni / Co / Al was 0.8 / 0.15 / 0.05. At the same time, a 20 wt% sodium hydroxide (NaOH) solution and a concentrated aqueous ammonia solution were administered. In this reaction, the dosage of sodium hydroxide (NaOH) solution was adjusted so that the pH of the metal salt solution in the reactor was about 11 to 13. The dosage was adjusted so that the residence time of the whole solution was about 10 hours.

Next, in the CSTR continuous reactor, the precipitated metal complex hydroxide was allowed to settle by the reaction time (1 day, 4 days and 7 days) according to each reaction time, and the supernatant was transferred to another container After the addition, the Raman measurement of the supernatant was performed and the intensity of the main peak of the sulfate (v1, frequency 980 cm ^-1 ) was measured. The results are shown in Fig. In Fig. 1, 1d, 4d and 7d are cases in which the reaction times are 1 day, 4 days, and 7 days, respectively. Referring to FIG. 1, the longer the reaction time, the stronger the Raman intensity is.

Then, the NiCoSO ₄ solution was prepared so as to have five concentrations of 0.01, 0.1, 0.5, 1, and 2, Raman intensity according to each concentration of the solution was obtained through Raman measurement, and Raman intensity of five concentrations was measured The results are shown in FIG. Referring to FIG. 3, the higher the concentration, the stronger the Raman intensity is.

The Raman intensities of FIGS. 1 and 3 were compared to determine the sulfate concentration of the metal complex hydroxide solution prepared by the coprecipitation method.

Example  2

The solution was prepared in the same manner as in Example 1, and an overflow solution according to each reaction time was taken according to the reaction time (1 day, 4 days and 7 days) in a CSTR continuous reactor, The solution was sonicated through a sonicator and connected to a silicone tube (Laboratory Made.) Connected with a thin glass by a metering pump. The solution was circulated so that no precipitate would be formed. In the same manner as in Example 1 Raman measurements were performed. The results are shown in Fig. In Fig. 2, 1d, 4d and 7d are cases in which the reaction times are 1 day, 4 days, and 7 days, respectively. Referring to FIG. 2, the longer the reaction time, the stronger the Raman intensity is.

Then, the NiCoSO ₄ solution was prepared so as to have five concentrations of 0.01, 0.1, 0.5, 1, and 2, Raman intensity according to each concentration of the solution was obtained through Raman measurement, and Raman intensity of five concentrations was measured The results are shown in FIG. Referring to FIG. 3, the higher the concentration, the stronger the Raman intensity is.

The Raman intensities of FIGS. 2 and 3 were compared to determine the sulfate concentration of the metal complex hydroxide solution prepared by the coprecipitation method.

Claims (5)

Injecting a primary metal salt solution containing nickel (Ni) and cobalt (Co) as a first metal salt into a reactor containing distilled water;
A secondary metal salt solution containing at least one selected from Al, Mn, Mg, Sr, Ca, Ge, Ga, In and Sb as a second metal salt is injected into the reactor simultaneously with the injection of the primary metal salt solution step;
Injecting a sodium hydroxide (NaOH) solution and an aqueous ammonia solution into the reactor to produce a metal complex hydroxide solution;
Measuring a Raman spectrum of the metal complex hydroxide solution by Raman spectroscopy;
Preparing a solution of Ni, Co sulfate solution having five concentrations of 0.01, 0.1, 0.5, 1 and 2 M, and measuring Raman spectrum by Raman spectroscopic analysis of each solution; And
And measuring the sulfate concentration of the metal complex hydroxide solution by comparing the Raman spectrum of the metal complex hydroxide solution with the Raman spectrum of each of the five concentrations of the Ni and Co sulfate solution.
The method according to claim 1,
Wherein the step of measuring the Raman spectrum of the metal complex hydroxide solution comprises:
Precipitating the nickel complex hydroxide precursor particles from the metal complex hydroxide solution and separating the nickel complex hydroxide precursor particles into a precipitate and a supernatant; And
Transferring the supernatant to a vessel, and performing Raman spectroscopic analysis on the supernatant.
The method according to claim 1,
Wherein the step of measuring the Raman spectrum of the metal complex hydroxide solution comprises:
And performing Raman spectroscopic analysis while circulating the metal complex hydroxide solution.
The method according to claim 1,
Wherein the concentration of the first metal salt in the first metal salt solution is 0.001 to 3 M and the residence time in the reactor is 5 to 50 hours.
The method according to claim 1,
Wherein the nickel composite hydroxide precursor particle size is adjusted to 1 to 30 탆.

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