KR20160099876A - Manufacturing method for Ni-Co-Mn composite precursor - Google Patents

Abstract

The present technique relates to a manufacturing method of a three-component complex precursor of nickel-cobalt-manganese (Ni_xCo_yMn_(1-x-y)). More particularly, the present technique relates to a manufacturing method of a high density three-component complex precursor to simultaneously produce a precursor having large sized particles, and a precursor having small sized particles. The manufacturing method comprises the following steps of: (a) manufacturing a precursor by a coprecipitation method of an aqueous metal solution including nickel sulfate, cobalt sulfate, and manganese sulfate in a reactor; (b) manufacturing a precursor by mixing the aqueous metal solution while having the precursor generated in the reactor as a seed; and (c) manufacturing a precursor by mixing the aqueous metal solution while having the precursor generated from the step (b) as a seed.

Description

[0001] The present invention relates to a method for producing a high-density nickel-cobalt-manganese composite precursor,

TECHNICAL FIELD The present invention relates to a process for producing a three-component complex precursor of nickel-cobalt-manganese (Ni _x Co _y Mn _{1 -xy} ), and more specifically, to a process for producing a three-component complex precursor used as a cathode active material for a lithium secondary battery Cobalt-manganese three-component complex precursor, which is characterized in that an opposite particle and a small particle are produced at the same time.

2. Description of the Related Art [0002] With the spread of portable small-sized electric and electronic devices, development of new secondary batteries such as nickel-metal hydride batteries and lithium secondary batteries is actively under way. Among them, the lithium secondary battery uses carbon such as graphite as an anode active material, a metal oxide containing lithium as a cathode active material, and a non-aqueous solvent as an electrolyte.

As a cathode active material used for a lithium secondary battery, nickel, cobalt, and manganese are mixed with lithium rather than lithium alone to prepare a cathode active material, thereby satisfying the anode 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 calcined to be used as a cathode active material. Usually, the precursor is prepared by coprecipitation. When a nickel salt, a manganese salt, and a cobalt salt are dissolved in distilled water and then fed into a reactor together with an aqueous ammonia solution (chelating agent) and an aqueous NaOH solution (basic aqueous solution) This happens.

In particular, precursors of both major and minor phases are prepared separately by conventional methods for producing a high-density cathode active material, followed by high-temperature firing together with a lithium source to prepare a cathode active material. In other words, it is necessary to further prepare a precursor of an opponent and a precursor respectively and mix them with a lithium source, and it is difficult to uniformly mix the major phase precursor and the major phase precursor in a powder state, have.

Patent Registration No. 10-1275845 Patent Publication No. 10-2013-0111413 Patent Publication No. 10-2013-0123910

It is another object of the present invention to provide a precursor preparation method capable of simultaneously producing a precursor of an opposite particle 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 relates to a nickel-cobalt-manganese composite precursor [Ni _x Co _y Mn _1-xy (OH) ₂ , Wherein a metal aqueous solution of nickel sulfate, cobalt sulfate and manganese sulfate in a reactor is prepared by coprecipitation in a reactor in the presence of 0 <x <1, 0 <y <1, 0 <x + y <(A); (B) preparing a precursor by coprecipitation by mixing a metal aqueous solution of nickel sulfate, cobalt sulfate, and manganese sulfate with the resulting precursor as a seed in the reactor; And (c) preparing a precursor by coprecipitation by mixing a metal aqueous solution of nickel sulfate, cobalt sulfate, and manganese sulfate with the precursor prepared in step (b) as a seed, wherein step (c) ) Is made higher than the concentration of the metal aqueous solution of the step (b). The present invention also provides a method for producing a high-density nickel-cobalt-manganese composite precursor.

Particularly, when the volume of the reactor is small, the step (b) is preferably repeated twice or more.

Particularly, when the volume of the reactor is small, the step (c) is preferably repeated twice or more.

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

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

Particularly, it is preferable to perform coprecipitation by adding NH ₄ OH and NaOH during the coprecipitation of steps (a) to (c).

Since the method of the present invention produces coarse particles (for example, 10 μm or more) and small particles (for example, 2 to 5 μm) at the same time in one coprecipitation process, It is not necessary to prepare the cathode active material by mixing the anode active material and the cathode active material with the lithium source and calcining them. In particular, when the precursor is prepared by the method of the present invention, since the major particles and the major particles are already uniformly mixed, there is an advantage that no extra time is required for mixing the major particles and the minor particles.

Figure 1 is a schematic representation of the method of the present invention.
2 and 3 are SEM measurement photographs and particle size distribution charts of Comparative Example 1, respectively.
4 and 5 are SEM measurement photographs and particle size distribution charts of Comparative Example 2, respectively.
6 and 7 are SEM measurement photographs and particle size distribution charts of Example 1, respectively.

Hereinafter, the present invention will be described. In the following description, "precursor" means a Ni _x Co _y Mn _1-xy (OH) ₂ precursor, 0 < x < 1, 0 < y &lt; In the present invention, the term "high density" means that the precursor of the opposite particle is mixed with the precursor of the precursor, so that the packing density of the precursor per the same volume is high.

The object of the present invention is to develop a high-density three-component precursor. It is advantageous in that it is possible to simultaneously produce the large particles and the large particles in one reactor, and thus a separate mixing step is not necessary.

When the concentration of the metal (nickel, cobalt, manganese) is increased during the reaction, the growth of the already prepared alleles is rather slowed and a new seed is formed to generate a large number of small particles, . That is, in the present invention, a metal solution of a certain concentration is used to initially produce an allele. When the allele grows to some extent, the concentration of the metal solution is increased for coarse growth.

Figure 1 is a schematic representation of the method of the present invention. Referring to FIG. 1, the present invention increases the size of the major particles and simultaneously produces small particles (2 to 5 占 퐉) by adjusting the concentration of the metal (here, the metal means nickel, cobalt and manganese) during the coprecipitation process.

Step (a)

The present invention relates to a nickel-cobalt-manganese composite precursor (Ni _x Co _y Mn _{1 -xy} (OH) _2, wherein, in the reactor, a metal aqueous solution of nickel sulfate, cobalt sulfate and manganese sulfate is co- 0 <x <1, 0 <y <1, 0 <x + y <1]. 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, the separated precursor is mixed with a metal aqueous solution of nickel sulfate, cobalt sulfate and manganese sulfate to prepare a precursor by co-precipitation. The precursor thus formed may be separated and recovered again, and then the step (b) may be repeated twice or more. This repetition can be achieved by increasing the size of the precursor to the desired size in lieu of the insufficient reactor size by repeating it when the volume of the reactor is small.

Step (c)

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

In particular, in addition to increasing the size of the precursor by controlling the concentration of the metal solution forming the precursor, the present invention can simultaneously produce the precursors while generating and growing the precursor using the precursor prepared in the previous step as a seed.

Hereinafter, the present invention is applied to a precursor of a composition which is mainly used as a three-component transition metal precursor which is a cathode active material for a lithium secondary battery, and which is mainly used as a three-component precursor having a high nickel component represented by the following formula (1).

[Chemical 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 examples.

Comparative Example  One

A 100 L double-tank reactor was filled with 60 L of distilled water, and the temperature was raised to 50 to 60 ° C by using a temperature holding device. Before the reaction, 5 L of NH ₄ OH solution was added and stirred at 500 to 600 rpm using an impeller.

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

The metal aqueous solution was continuously pumped into the reactor at a rate of 6.66 L / hr by means of a metering pump, which was mixed with 20 L / m _{2 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 was pumped to the reactor through a pH control device to maintain the pH of 9.8 to 10.2.

The reaction time was 3 hours per step for a total of 9 hours. The batch type coprecipitation method of removing the waste solution on the basis of 3 hours (one step) was applied, which can not continuously react on the volume of the reactor. After each (3 hour reaction), the powder was allowed to settle, the supernatant was removed and the next step was restarted and 2 L of NH ₄ OH was added just before the new step.

Figs. 2 and 3 are SEM photographs and particle size distributions of the precursor particles prepared in Comparative Example 1, respectively. The median size of the particles was 8.3 ㎛, indicating a relatively uniform particle size distribution and becoming an antagonist.

Comparative Example  2

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

Figs. 4 and 5 are SEM photographs and particle size distributions of the precursor particles prepared in Comparative Example 2. Fig. The median size of the particles was 10.4 ㎛. The particle size distribution of the particles was relatively uniform and almost no fine particles were formed.

That is, when the concentration of the metal aqueous solution is the same, it is confirmed that almost no particles are generated even when the step (repetition unit) is repeated several times, and only almost all the particles are generated.

The density of the precursor prepared by the method of Comparative Example 2 was measured and the results are shown in Table 1 below.

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

Example  One

After the reaction for 3 hours (9 hours) as in Comparative Example 1, 60 L of a 180 M metal aqueous solution was added and the concentration of the aqueous metal solution was increased 1.2 times. The other reaction conditions were the same as those in Comparative Example 1, Step 3 After the reaction of the remaining 4 to 6 steps (total 18 hours), the obtained three-component transition metal precursor was washed with distilled water several times in a filtering manner and dried in a constant temperature drier at 120 ° C for 20 hours to obtain a nickel- A precursor was obtained.

Figs. 6 and 7 are SEM photographs and particle size distributions of the precursor particles prepared in Example 1. Fig. As shown in the particle size distribution chart of FIG. 7, it was confirmed that minor particles of 2 to 5 μm were formed together with major particles (10 μm or more). That is, in the case of producing the precursor through repetition of coprecipitation in the same concentration of metal aqueous solution (complex solution of nickel sulfate, cobalt sulfate, and manganese sulfate) under the same condition as the conventional method, only the opponent was produced.

The densities of the precursors prepared by the method of Example 1 were measured and the results are shown in Table 2 below.

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

When the results of Table 1 and Table 2 are compared, it can be seen that the density of the precursor prepared by the present invention is 2.0779 on average, but 0.7129 when prepared by the method of Comparative Example 2, Density, that is, the production of a high-density precursor.

It is not necessary to prepare the cathode active material by mixing the cathode active material with the lithium source and subjecting the anode active material and the anode active material to a calcining process. .

Claims (6)

Manganese complex precursor Ni _x Co _y Mn _{1 -xy} (OH) ₂ of an opposite particle and a small particle, 0 <x <1, 0 <y <1, 0 <x + y <1]
(A) preparing a precursor by coprecipitation of a metal aqueous solution of nickel sulfate, cobalt sulfate and manganese sulfate in a reactor;
(B) preparing a precursor by coprecipitation by mixing a metal aqueous solution of nickel sulfate, cobalt sulfate, and manganese sulfate with the resulting precursor as a seed in the reactor; And
(C) preparing a precursor by coprecipitation by mixing a metal aqueous solution of nickel sulfate, cobalt sulfate, and manganese sulfate with the precursor prepared in the step (b) as a seed,
Wherein the concentration of the metal aqueous solution in the step (c) is higher than the concentration of the metal aqueous solution in the step (b).
The method of claim 1, wherein the step (b) is repeated at least twice.
The method of claim 1, wherein the step (c) is repeated at least twice.
The method of claim 1, wherein the concentrations of the metal aqueous solutions of steps (a) and (b) are the same.
The method of claim 1, wherein the concentration of the metal aqueous solution of step (c) is 1.1 to 1.5 times higher than the concentration of the metal aqueous solution of step (b).
The method of claim 1, wherein coprecipitation is carried out by adding NH ₄ OH and NaOH as coprecipitates during the coprecipitation of steps (a) to (c).

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