WO2016129733A1

WO2016129733A1 - Method for preparing high-density nickel-cobalt-manganese composite precursor

Info

Publication number: WO2016129733A1
Application number: PCT/KR2015/001700
Authority: WO
Inventors: 권순모; 권오상; 강동구
Original assignee: 주식회사 이엔드디
Priority date: 2015-02-13
Filing date: 2015-02-23
Publication date: 2016-08-18
Also published as: KR20160099876A

Abstract

The present invention relates to a method for preparing a nickel-cobalt-manganese ternary composite precursor (Ni_xCo_yMn_1-x-y) and, more particularly, to a method for preparing a high-density ternary precursor, the method in which large particle and fine particle precursors are simultaneously generated by means of co-precipitation.

Description

Method for producing high density nickel-cobalt-manganese composite precursor

The present invention relates to a method for producing a nickel-cobalt-manganese three-component composite precursor (Ni _x Co _y Mn _1-xy ), more specifically a method of manufacturing a three-component composite precursor used as a positive electrode active material for lithium secondary batteries It is a technique related to a method for producing a nickel-cobalt-manganese three-component composite precursor, characterized in that the large particles and small particles are generated at the same time.

With the spread of portable small electric and electronic devices, development of new secondary batteries such as nickel-metal hydride batteries and lithium secondary batteries has been actively conducted. Among them, a lithium secondary battery is a battery in which carbon such as graphite is used as a negative electrode active material, a metal oxide containing lithium is used as a positive electrode active material, and a nonaqueous solvent is used as an electrolyte.

As a positive electrode active material used in a lithium secondary battery, nickel, cobalt, manganese, and the like, instead of lithium, are mixed to produce a positive electrode active material, thereby satisfying positive electrode properties such as energy density and electrical conductivity. For example, Li ₂ CO ₃ and a nickel-cobalt-manganese precursor (Ni _x Co _y Mn _1-xy ) are mixed and processed to be used as a positive electrode active material. Usually, the precursor is prepared using a coprecipitation method, and after the nickel salt, manganese salt and cobalt salt are dissolved in distilled water, and then introduced into the reactor together with an aqueous ammonia solution (chelating agent) and an aqueous NaOH solution (basic aqueous solution), the precursor precipitates. This happens.

In particular, conventionally prepared precursors of the alleles and small particles in a conventional method for producing a high-density positive electrode active material, and then calcined at high temperature with a lithium raw material to produce a positive electrode active material. That is, not only an additional process of preparing the precursors of the large particles and the small particles and mixing them with the lithium raw material is necessary, but also difficult to uniformly mix the powder when the large particles and the small particle precursors are mixed. have.

It is an object of the present invention to provide a precursor production method for simultaneously producing a precursor of an allele and a small particle during a coprecipitation reaction for preparing a three-component precursor of nickel-cobalt-manganese for a cathode active material of a lithium secondary battery.

The present invention provides a nickel-cobalt-manganese composite precursor of alleles and small particles [Ni _x Co _y Mn _1-xy (OH) _2, wherein In the method of coprecipitation production of 0 <x <1, 0 <y <1, 0 <x + y <1] simultaneously, the precursor is manufactured by coprecipitation of the aqueous metal solution of nickel sulfate, cobalt sulfate, and manganese sulfate in a reactor. (A); (B) preparing a precursor by coprecipitation by mixing a metal solution of nickel sulfate, cobalt sulfate, and manganese sulfate as a seed in the reactor; And (c) preparing a precursor by coprecipitation by mixing a metal solution of nickel sulfate, cobalt sulfate, and manganese sulfate, using the precursor prepared by the step (b) as a seed, wherein the step (c) The concentration of the aqueous metal solution of c) is higher than the concentration of the aqueous metal solution of step (b) to provide a method for producing a high density nickel-cobalt-manganese composite precursor.

In particular, when the volume of the reactor is small, the step (b) is preferably repeated two or more times.

In particular, when the volume of the reactor is small, the step (c) is preferably repeated two or more times.

In particular, the concentration of the aqueous metal solution of step (a) and step (b) may be the same.

In particular, the concentration of the aqueous metal solution of step (c) is preferably 1.1 times to 1.5 times higher than the concentration of the aqueous metal solution of step (b).

In particular, in the coprecipitation method of steps (a) to (c), it is preferable to perform coprecipitation by adding NH ₄ OH and NaOH.

In the method of the present invention, since alleles (for example, 10 µm or more) and small particles (for example, 2 to 5 µm) are simultaneously generated in one coprecipitation process, unlike the conventional method, the coprecipitation method is performed separately. There is no need to prepare a positive electrode active material by making a large particle and a small particle through the mixing and plastic processing with a lithium source. In particular, when the precursor is prepared by the method according to the present invention, since the alleles and the small particles are already uniformly mixed, there is an advantage that a separate time for mixing the alleles and the small particles is not necessary.

1 is a diagram illustrating the method of the present invention.

2 and 3 are SEM photographs and particle size distribution of Comparative Example 1, respectively.

4 and 5 are SEM photographs and particle size distribution diagrams of Comparative Example 2, respectively.

6 and 7 are SEM photographs and particle size distribution diagrams of Example 1, respectively.

Hereinafter, the present invention will be described, in the following description, "precursor" means Ni _x Co _y Mn _1-xy (OH) ₂ precursor, wherein 0 <x <1, 0 <y <1, 0 <x + y <1. In addition, in the present invention, "high density" means that the precursors of the alleles and the small particles are mixed so that the filling density of the precursors per volume is high.

An object of the present invention is to develop a high density three-component precursor. Alleles and small particles can be produced at the same time in one reactor, there is an advantage that no separate mixing process is required.

In the present invention, when the concentration of metals (nickel, cobalt, manganese) is increased during the reaction, the growth of alleles already prepared is rather slow and new seeds are formed to produce a large number of small particles, thereby simultaneously producing alleles and small particles. It is characterized by that. That is, in the present invention, a metal solution of a certain concentration is initially used to generate alleles. When the alleles are grown to some extent, this time, the concentration of the metal solution is increased for the growth of the small particles.

1 is a diagram illustrating the method of the present invention. Referring to FIG. 1, the present invention controls the concentration of metal (where metal means nickel, cobalt, and manganese) during the coprecipitation process, thereby simultaneously increasing the size of alleles and simultaneously producing small particles (2 to 5 μm).

Step (a)

The present invention provides a nickel-cobalt-manganese composite precursor [Ni _x Co _y Mn _1-xy (OH) _2, wherein, by coprecipitation of an aqueous metal solution of nickel sulfate, cobalt sulfate and manganese sulfate in a reactor. 0 <x <1, 0 <y <1, 0 <x + y <1] are manufactured. In the coprecipitation, sodium hydroxide and an aqueous ammonia solution are used as in the prior art.

Step (b)

After separating and recovering only the prepared precursor, a precursor is prepared by coprecipitation by mixing the separated precursor with an aqueous metal solution of nickel sulfate, cobalt sulfate and manganese sulfate. The precursor thus produced may be separated and recovered again, and then the step (b) may be repeated two or more times. This repetition is because by repeating when the volume of the reactor is small, it is possible to increase the size of the precursor to the desired size in place of the insufficient reactor size.

Step (c)

After the step (b), this time using a metal solution of a higher concentration than the step (b), the precursor is prepared by coprecipitation of the precursor and the metal solution as in step (b). In addition, step (c) may be repeated as necessary. The concentration of the aqueous metal solution in step (c) compared to step (b) is preferably 1.1 times to 1.5 times, but is not limited thereto.

In particular, the present invention may be prepared at the same time while producing and growing a precursor by using the precursor made in the previous step as a seed (seed) in addition to increasing the size of the precursor by adjusting the concentration of the metal solution constituting the precursor.

In the following experiment, the three-component transition metal precursor, which is a cathode active material for a lithium secondary battery, was applied to a precursor having a composition mainly used as a three-component precursor having a high nickel component according to the following formula (1).

[Formula 1]

Ni _0.8 Co _0.1 Mn _0.1 (OH) ₂

Hereinafter, the present invention will be described in more detail with reference to the following examples.

비교예 1Comparative Example 1

60L of distilled water was charged to a 100L double tank reactor, and the temperature was raised to 50 to 60 ° C using a temperature maintaining apparatus. Before the reaction, 5 L of NH ₄ OH solution was added thereto, and the mixture was stirred and mixed well by using an impeller at a speed of 500 to 600 rpm.

To prepare the precursor of Chemical Formula 1, nickel sulfate, cobalt sulfate, and manganese sulfate were mixed in a molar ratio of 0.8: 0.1: 0.1 to prepare 60 L of a metal solution of 150 M concentration, and 40 L of 40-50% sodium hydroxide aqueous solution was prepared. It was.

The aqueous metal solution was continuously pumped into the reactor at 6.66 L / hr with a metering pump, which was mixed with 20 L / m of N ₂ gas and introduced into the reactor. The aqueous sodium hydroxide solution was used to control the pH atmosphere during the reaction and the pH was pumped into the reactor in conjunction with the pump through the pH control equipment to maintain a pH of 9.8 ~ 10.2.

The reaction time was 3 hours per step for a total of 9 hours. Batch type co-precipitation of the method of removing the waste liquid on the basis of three hours (one step) is not possible. After each (3 h reaction) the precursor was allowed to settle and the supernatant was removed to restart the next step and NH ₄ OH 2L was added immediately before the new step.

2 and 3 are SEM measurements and particle size distribution of the precursor particles produced by Comparative Example 1, respectively. The median size was 8.3 μm, showing a relatively uniform particle size distribution, indicating that the median size was becoming an allele.

비교예 2Comparative Example 2

The reaction was carried out under the same conditions as in Comparative Example 1, and the coprecipitation was repeated up to two times as long as that of Comparative Example 1, that is, 6 steps. After completion of the reaction (18 hours-6 steps in total), the obtained three-component transition metal precursor was washed with distilled water several times by a filtering method, and dried in a 120 ° C. constant temperature dryer for 20 hours to obtain a nickel-cobalt-manganese three-component precursor.

4 and 5 are SEM measurement photographs and particle size distribution of the precursor particles prepared by Comparative Example 2. The median size was 10.4 μm, indicating a relatively uniform particle size distribution of the alleles, with little particles being produced.

That is, when the concentration of the aqueous metal solution was the same, it was confirmed that even when the step (repeated unit) was repeated several times, almost no small particles were produced but almost all particles were produced.

As a result of measuring the density of the precursor prepared by the method of Comparative Example 2 was as Table 1 below.

Table 1

	1 time	Episode	2	3rd time	4 times	5 times	Average
Density (g / cm ² )	0.7202	0.7148	0.7098	0.7120	0.70780	0.7129

실시예 1Example 1

After the three-step reaction (9 hours) as in Comparative Example 1, the concentration of the metal aqueous solution was increased 1.2 times to prepare a 60 M metal aqueous solution of 180 M concentration, and the other reaction conditions were the same as those in Comparative Example 1 Step 3 The three-component transition metal precursors obtained after the reaction of the remaining four to six steps in total (18 hours in total) were washed with distilled water several times by a filtering method, and dried in a 120 ° C. constant temperature dryer for 20 hours to form a nickel-cobalt-manganese three-component system. A precursor was obtained.

6 and 7 are SEM photographs and particle size distribution of the precursor particles prepared by Example 1. As shown in the particle size distribution of FIG. 7, it was confirmed that small particles of 2 to 5 μm were formed together with alleles (10 μm or more). That is, when the precursor is prepared through the repeated process of co-precipitation in the same concentration of the metal aqueous solution (nickel sulfate, cobalt sulfate, manganese sulfate complex solution) under the same conditions, a large difference was generated.

As a result of measuring the density of the precursor prepared by the method of Example 1 was as Table 2 below.

TABLE 2

	1 time	Episode	2	3rd time	4 times	5 times	Average
Density (g / cm ² )	2.0698	2.0801	2.0813	2.0794	2.0788	2.0779

Comparing the results of Table 1 and Table 2, the density of the precursor prepared by the present invention is 2.0779 on average, but when prepared by the method of Comparative Example 2 at a density of 0.7129 of about 3 times It was found that the density, ie, the preparation of high density precursors is possible.

Since the alleles and the small particles are produced in one coprecipitation process at the same time as in the method of the present invention, it is not necessary to prepare the positive active material by mixing them with a lithium source and then plasticizing them by making each of the alleles and the small particles through a separate coprecipitation method. .

Claims

Nickel-cobalt-manganese composite precursors of alleles and small particles [Ni x Co y Mn 1-xy (OH) 2, wherein In the method of coprecipitation production of 0 <x <1, 0 <y <1, 0 <x + y <1] simultaneously,

(A) preparing a precursor by coprecipitation of an aqueous metal solution of nickel sulfate, cobalt sulfate and manganese sulfate in a reactor;

(B) preparing a precursor by coprecipitation by mixing a metal solution of nickel sulfate, cobalt sulfate, and manganese sulfate as a seed in the reactor; And

(C) preparing a precursor by a coprecipitation method by mixing a metal solution of nickel sulfate, cobalt sulfate, and manganese sulfate as a seed prepared by the step (b), and

The concentration of the aqueous metal solution of step (c) is higher than the concentration of the aqueous metal solution of step (b) method for producing a high density nickel-cobalt-manganese composite precursor.
The method of claim 1, wherein the step (b) is repeated two or more times method of producing a high density nickel-cobalt-manganese composite precursor.
The method of claim 1, wherein step (c) is repeated two or more times.
The method of claim 1, wherein the concentration of the aqueous metal solution of step (a) and step (b) is the same, characterized in that the high density nickel-cobalt-manganese composite precursor.
The method of claim 1, wherein the concentration of the aqueous metal solution of step (c) is 1.1 times to 1.5 times higher than the concentration of the aqueous metal solution of step (b).
The method of claim 1, wherein the coprecipitation is performed by adding NH 4 OH and NaOH as a coprecipitation solution during the coprecipitation method of steps (a) to (c).