KR20240068187A - Manufacturing method for highly densified Ni-Co-Mn composite precursor for Litium secondary battery - Google Patents

Abstract

The present invention relates to a method for manufacturing a high-density nickel-cobalt-manganese composite precursor. In addition, the precursor nucleation process and the particle growth process are divided by adjusting the pH, and the ionic strength is increased to suppress nucleation in a colloidal environment. , characterized in that it further contains sodium sulfate to promote particle growth.

Description

Manufacturing method for highly densified Ni-Co-Mn composite precursor for Litium secondary battery}

The present invention provides _a 3 _- component composite precursor of nickel-cobalt-manganese _for lithium secondary batteries ( _Ni This is a technology related to the manufacturing method of 1), and in particular, it relates to a technology for manufacturing a high-density nickel-cobalt-manganese composite precursor with a small particle diameter of 5㎛ or less.

As the spread of portable, small-sized electrical and electronic devices increases, the development of new types of secondary batteries such as nickel hydride batteries and lithium secondary batteries is actively underway. Among these, lithium secondary batteries are batteries that use carbon such as graphite as a negative electrode active material, a metal oxide containing lithium as a positive electrode active material, and a non-aqueous solvent as an electrolyte.

The cathode active material used in lithium secondary batteries is manufactured by mixing nickel, cobalt, manganese, etc., rather than lithium alone, to satisfy cathode physical properties such as energy density and electrical conductivity. For example, Li ₂ CO ₃ and nickel-cobalt-manganese composite precursor (Ni _x Co _y Mn _1-xy (OH) ₂ ) are mixed and processed to be used as a positive electrode active material. Typically, the nickel-cobalt-manganese composite precursor is manufactured using a coprecipitation method, in which nickel salt, manganese salt, and cobalt salt are dissolved in distilled water, then ammonia aqueous solution (chelating agent) and NaOH aqueous solution (basic aqueous solution, pH adjuster) When placed together in a reactor, a nickel-cobalt-manganese composite precursor is precipitated through a coprecipitation reaction.

In the production of a nickel-cobalt-manganese composite precursor, manufacturing a nickel-cobalt-manganese composite precursor with uniform particle distribution is an important research task. In order to achieve high performance (high cycle characteristics, low resistance, high output) in lithium secondary batteries, it is required that the positive electrode material be composed of particles with a uniform and appropriate particle size. This is achieved by using a material with a large particle size and a small specific surface area. Because a sufficient reaction area with the electrolyte cannot be secured, reaction resistance increases, making it impossible to obtain a high-output battery, and if materials with a wide particle size distribution are used, problems such as lower battery capacity and increased reaction resistance arise. am. The reason why the battery capacity decreases is because the voltage applied to the particles within the electrode becomes non-uniform and the fine particles selectively deteriorate when charging and discharging are repeated. Therefore, in order to improve the performance of the anode material, the nickel-cobalt-manganese composite precursor needs to be manufactured with a small particle size of an appropriate size, uniform particle size, and high density.

As a technology for producing a nickel-cobalt-manganese composite precursor with a uniform particle size distribution of small particle size, in International Publication No. WO2004/092073, an aqueous solution of nickel cobalt manganese salt, an aqueous alkali metal hydroxide solution, and an ammonium ion supplier are each continuously used. Alternatively, the reaction system is intermittently supplied to the reaction system, the temperature of the reaction system is maintained at a substantially constant value within the range of 30 to 70°C, and the reaction is allowed to proceed while maintaining the pH at an approximately constant value within the range of 10 to 13, thereby forming a nickel cobalt manganese complex. The technology to precipitate hydroxide is being disclosed. The patent discloses that an intermediate with a desirable particle size distribution can be obtained by performing the reaction in multiple stages rather than in one stage.

In Patent Publication No. 10-2012-0099098, nickel cobalt manganese with small particle size and uniform particle size distribution is produced through two-step pH control, which involves generating precursor nuclei at pH 12 to 14 and growing precursor particles at pH 10 to 12. A method for producing composite hydroxide particles is disclosed.

In the above prior art, it is disclosed that the pH is changed when manufacturing the nickel-cobalt-manganese composite precursor, but there are limitations in producing the desired high-density, small-diameter composite precursor in a short time simply by varying the pH. .

Patent Document 1: International Publication No. WO2004/092073 Patent Document 2: Patent Publication No. 10-2012-0099098

The purpose of the present invention is to provide a method of manufacturing a nickel-cobalt-manganese composite precursor with a small particle size of 5 μm or less at high density.

In addition, the purpose of the present invention is to provide a method for producing a nickel-cobalt-manganese composite precursor more efficiently by improving the conventional method of manufacturing a nickel-cobalt-manganese composite precursor through two-stage pH control.

The present invention is a method for producing _{a nickel -} cobalt-manganese composite precursor ( _Ni , a coprecipitation solution containing a transition metal-containing solution containing nickel, cobalt, and manganese, an ammonium ion solution, and a sodium hydroxide solution is placed in a batch reactor, and then the coprecipitation reaction is performed at a temperature of 50 to 60°C and pH of 12.0 to 13.0. , precursor nucleation process (1); and a precursor particle growth process (2) in which a coprecipitation reaction is performed by lowering the pH of the reactor to 10.0 to 11.5, wherein the ionic strength is increased in the reactor of the precursor nucleation process (1) to generate precursor nuclei in a colloidal environment. Provided is a method for producing a high-density nickel-cobalt-manganese composite precursor, characterized in that additional sodium sulfate is added to create an environment that inhibits and promotes precursor nuclear growth.

In particular, the precursor nucleation process (1) and the precursor particle growth process (2) can be repeated.

In particular, sodium sulfate may not be added separately in the repeated process.

In particular, the precursor nucleation process (1) may proceed for 10 to 30 minutes.

In particular, the precursor particle growth process (2) can be performed for 60 to 120 minutes.

In particular, the nickel, cobalt, and manganese may be NiSO ₄ .6H ₂ O, CoSO ₄ .7H ₂ O, and MnSO ₄ .H ₂ O, respectively.

In particular, the precursor nucleation process (1) and the precursor particle growth process (2) may be performed under stirring conditions of 700 to 1000 rpm.

In particular, the concentration of sodium sulfate introduced into the batch reactor may be 0.01 to 2.5M.

In particular, after completion of the coprecipitation reaction, the prepared composite precursor is repeatedly washed with deionized water and alkaline water to remove impurities, and after removing the impurities, a composite precursor with a low moisture content can be manufactured through hot air drying.

A method for producing a nickel-cobalt-manganese composite precursor according to the present invention with high density and small particle size in a short time by co-precipitation is provided. In particular, in the present invention, by adding sodium sulfate to suppress precursor nucleation in a colloidal environment and create conditions that promote particle growth, a method can be used to quickly produce high-density composite precursors with small particle diameters of 5㎛ or less on average. provides.

1 is a flow chart explaining the method of the present invention.
Figure 2 is a particle size distribution chart of the composite precursor prepared according to the example.
Figure 3 is a particle size distribution chart of the composite precursor prepared by Comparative Example.

The _present invention relates to a _{nickel -} cobalt-manganese composite precursor ( _Ni y<1, hereinafter abbreviated as “composite precursor” or “precursor”). In particular, the present invention provides a method for producing a high-density, small-particle diameter composite precursor with an average particle diameter of 5 μm or less.

1 is a flow chart explaining the method of the present invention. The method of the present invention will be described with reference to Figure 1.

Specifically, the present invention involves adding a coprecipitation solution containing a transition metal-containing solution containing nickel, cobalt, and manganese, an ammonium ion solution, and a sodium hydroxide solution into a batch reactor, and then reacting at a temperature of 50 to 60°C and pH of 12.0 to 13.0. Precursor nucleation process through coprecipitation reaction (1); and a precursor particle growth process (2) in which a coprecipitation reaction is performed by lowering the pH of the reactor to 10.0 to 11.5, wherein the ionic strength is increased in the reactor of the precursor nucleation process (1) to suppress precursor nucleation in a colloidal environment. In addition, a method for producing a high-density nickel-cobalt-manganese composite precursor is provided, characterized in that additional sodium sulfate is added to create an environment that promotes the growth of precursor particles. In the present invention, if too many nuclei are generated during the coprecipitation reaction, the particle growth rate relative to ammonium ions is low, making it impossible to grow to the desired particle size, and if too few nuclei are generated, the particle growth rate relative to ammonium ions is too high, resulting in obtaining a precursor with a particle size larger than the desired particle size. A small particle size precursor is manufactured by controlling nucleation and particle growth by controlling pH conditions and ionic strength using sodium sulfate.

After the above processes (1) and (2), processes (1) and (2) can be repeated in order to produce a high-density, small-diameter composite precursor of the desired size. The number of such repetitions varies depending on reaction conditions and the average particle size of the desired composite precursor.

The precursor nucleation process (1) can be carried out for 10 to 30 minutes, and the precursor particle growth process (2) can be carried out for 60 to 120 minutes, but the time range other than the above can be adjusted depending on the situation.

The nickel, cobalt, and manganese may be preferably added to the batch reactor as NiSO ₄ ㆍ6H ₂ O, CoSO ₄ ㆍ7H ₂ O, and MnSO ₄ ㆍH ₂ O, respectively, but may also be used as compounds other than the above compounds. It can be put into a batch reactor.

The precursor nucleus formation process (1) and the precursor particle growth process (2) are preferably carried out under stirring in order to maintain a uniform reaction concentration within the reactor, and may be carried out under stirring conditions of 700 to 1000 rpm.

Sodium sulfate introduced into the batch reactor may be added at a concentration of 0.01M to 2.5M, but may be added or subtracted from the above range depending on reaction conditions. Sodium sulfate is added to the batch reactor in a state dissolved in deionized water. can be put in.

After completion of the coprecipitation reaction, the prepared composite precursor is repeatedly washed with deionized water and alkaline water to remove impurities, and then hot air dried to produce a composite precursor with a low moisture content. Since these cleaning and drying steps are well-known techniques, detailed description will be omitted.

Example

Aqueous ammonia and NaOH were added to a batch reactor (5L) to adjust the pH to 12.5, then purged with nitrogen gas to remove dissolved oxygen, and then stirred at a temperature of 60°C and a stirring speed of 900 rpm to form a vortex inside the reactor.

Deionized water and sodium sulfate were added to the reactor so that the concentration of sodium sulfate in the reactor was 0.1M to increase the ionic strength to create an environment that suppresses nucleation in a colloidal environment and promotes particle growth.

NiSO ₄ ㆍ6H ₂ O, CoSO ₄ ㆍ7H ₂ O, MnSO ₄ ㆍH ₂ O are mixed in deionized water in an amount such that the molar ratio of nickel:cobalt:manganese is 8:1:1 to contain 2.5M of transition metal. A solution was prepared.

Thereafter, the transition metal-containing solution was introduced into the reactor and co-precipitated for 30 minutes to form particle nuclei of nickel cobalt manganese hydroxide.

Next, a transition metal-containing solution and NaOH were added to adjust the pH to 11, and precursor particle growth was performed for 120 minutes.

By repeating the above two processes (precursor nucleation, precursor particle growth), a positive electrode active material composite precursor with an average particle diameter (D ₅₀ ) of 5.0 μm and an average composition of Ni _0.80 Co _0.10 Mn _0.10 (OH) ₂ was manufactured.

After the production of the composite precursor by co-precipitation was completed, impurities were generated in an environment to increase ionic strength, so the impurity concentration was controlled through repeated deionized water/alkaline washing, and a hydroxide precursor with a low moisture content was dried with hot air at 120°C for 24 hours. was obtained.

Comparative example

Aqueous ammonia and NaOH were added to the batch reactor to adjust the pH to 11.3, then purged with nitrogen gas to remove dissolved oxygen, and then stirred at a temperature of 60°C and a stirring speed of 900 rpm to form a vortex inside the reactor.

NiSO ₄ ㆍ6H ₂ O, CoSO ₄ ㆍ7H ₂ O, MnSO ₄ ㆍH ₂ O are mixed in deionized water in an amount such that the molar ratio of nickel:cobalt:manganese is 8:1:1 to contain 2.5M of transition metal. A solution was prepared.

Afterwards, the transition metal-containing solution was introduced into the reactor and co-precipitated for 150 minutes to prepare a nickel-cobalt-manganese composite precursor.

Experiment example

Experimental Example 1: Particle size distribution

Figure 2 is a particle size distribution diagram of the composite precursor of this example, and Figure 3 is a particle size distribution diagram of the composite precursor of the comparative example. The composite precursors of Examples and Comparative Examples achieved a target average particle diameter (D50) of 5 ㎛ or less with a relatively short reaction time. However, it can be confirmed through the particle size distribution diagrams in FIGS. 2 and 3 that the composite precursor of the example is manufactured with a more uniform size compared to the comparative example.

Experimental Example 2: Tap density

Although the composite precursors of the Examples and Comparative Examples all satisfied an average particle diameter (D ₅₀ ) of 5.0 μm or less, the results of measuring the tap density in the composite precursors of the Examples and Comparative Examples prepared during the same reaction time are shown in Table 1 below. As a result of measuring the tap density, it was confirmed that the composite precursor of the example had a higher tap density than the composite precursor of the comparative example and was manufactured at a relatively high density.

Tap density(g/cm ³ ) Example 1.83 Comparative example 1.67

Claims (8)

Nickel-cobalt-manganese composite precursor (Ni _x Co _y Mn _1-xy (OH) _2, where, As a manufacturing method of 0<x<1, 0<y<1, 0<x+y<1),
After adding a coprecipitation solution containing a transition metal-containing solution containing nickel, cobalt, and manganese, an ammonium ion solution, and a sodium hydroxide solution to a batch reactor, the precursor undergoes a coprecipitation reaction at a temperature of 50 to 60°C and pH of 12.0 to 13.0. Nucleation process (1); and
It includes a precursor particle growth process (2) in which a coprecipitation reaction is performed by lowering the pH in the reactor to 10.0 to 11.5,
High-density nickel for lithium secondary batteries, characterized in that sodium sulfate is further added to the reactor of the precursor nucleation process (1) to increase ionic strength to suppress precursor nucleation in a colloidal environment and to create an environment that promotes precursor particle growth. -Method for manufacturing cobalt-manganese composite precursor.
The method of claim 1, wherein the precursor nucleation process (1) and the precursor particle growth process (2) are repeated one or more times.
In claim 1, the precursor nucleation process (1) is performed for 10 to 30 minutes.
In claim 1, the precursor particle growth process (2) proceeds for 60 to 120 minutes, Method for manufacturing high-density nickel-cobalt-manganese composite precursor for lithium secondary batteries.
In claim 1, the nickel, cobalt, and manganese are NiSO ₄ ㆍ6H ₂ O, CoSO ₄ ㆍ7H ₂ O, and MnSO ₄ ㆍH ₂ O, respectively. A method for producing a high-density nickel-cobalt-manganese composite precursor for a lithium secondary battery.
In claim 1, the precursor nucleation process (1) and the precursor particle growth process (2) are performed under stirring conditions of 700 to 1000 rpm.
In claim 1, the concentration of sodium sulfate is 0.01 to 2.5M, Method for manufacturing high-density nickel-cobalt-manganese composite precursor for lithium secondary batteries.
In claim 1, the composite precursor prepared by the coprecipitation reaction is repeatedly washed with deionized water and alkaline water to remove impurities, and then dried with hot air to produce a composite precursor with a low moisture content. Method for manufacturing cobalt-manganese composite precursor.