KR20220042657A - Manufacturing method of positive electrode material of nikel-rich lithium composite transition metal oxide in a form of a single particle and manufacturing method of positive electrode material of nikel-rich lithium composite transition metal oxide in a form of a single particle formed therefrom - Google Patents

Abstract

The present invention relates to a method for preparing positive electrode active material single particles of nickel-rich lithium transition metal composite oxide, including the steps of: (S1) preparing a hollow composite transition metal precursor having a hollow particle shape having a core portion formed of a vacant space and a shell portion surrounding the core portion, and having a nickel content of 80 mol% or higher based on the total transition metals; and (S2) mixing the hollow composite transition metal precursor with a lithium source material, and firing the resultant mixture at a temperature of 800-870℃ in such a manner that the mixture may be over-fired until the particles grown by the firing cause popping in the form of single particles, thereby preparing a composite transition metal oxide in the form of single particles. According to the method of the present invention, it is possible to obtain positive electrode active material single particles of nickel-rich lithium transition metal composite oxide with ease even at a relatively low over-firing temperature.

Description

A method for producing single particles of a lithium composite transition metal oxide positive electrode active material containing a high content of nickel, and single particles of a lithium composite transition metal oxide positive electrode active material containing a high content of nickel formed therefrom OXIDE IN A FORM OF A SINGLE PARTICLE AND MANUFACTURING METHOD OF POSITIVE ELECTRODE MATERIAL OF NIKEL-RICH LITHIUM COMPOSITE TRANSITION METAL OXIDE IN A FORM OF A SINGLE PARTICLE FORMED THEREFROM}

The present invention relates to a method for manufacturing a single particle type positive electrode active material made of a lithium composite transition metal oxide containing a high content of nickel and a single particle type positive electrode active material formed therefrom.

A cathode active material made of a high nickel-rich lithium composite transition metal oxide exhibiting a high energy density is attracting attention, but there is a problem in that the lifespan stability of the battery is rapidly reduced as the nickel content increases. One of the causes of the decrease in lifespan is related to the structure of the positive electrode active material made of a high nickel-rich (Ni-rich) lithium composite transition metal oxide.

A positive active material made of a conventional high-content nickel-rich lithium composite transition metal oxide in the form of secondary particles in which primary particles are aggregated causes cracks at the interface between primary particles as charging and discharging proceed. This reduces the lifespan of the battery.

Accordingly, development of a positive electrode active material made of a nickel-rich (Ni-rich) lithium composite transition metal oxide having a high content in the form of single particles rather than in the form of secondary particles is being conducted. The single-particle type positive active material without grain boundaries can greatly reduce the generation of micro or macro-cracks, so it is a lithium composite transition metal oxide containing high nickel content (Ni-rich). increase the structural stability of the positive electrode active material.

There are various methods for preparing single particles of a positive electrode active material made of a high nickel content (Ni-rich) lithium composite transition metal oxide, but among them, the most used method is a composite transition metal containing a high nickel content using a co-precipitation method. After synthesizing the precursor particles, they are mixed with a lithium raw material and subjected to under-calcination, whereby the particles grown by sintering are popped to produce a cathode active material made of a lithium composite transition metal oxide containing a high content of nickel formed in the form of single particles.

The higher the nickel content is, the lower the firing temperature is to prevent deterioration of the cathode active material performance. Therefore, the firing temperature should be low even during under-calcination for single particle production. However, when the over-calcination temperature is lowered, the composite transition metal precursor particles do not grow well due to the seed portion having a relatively lower density than the shell portion of the composite transition metal precursor particles. Particle formation is difficult and the seed portion of the composite transition metal precursor particle remains as it is.

Therefore, the problem to be solved by the present invention is to provide a method capable of easily producing single particles of a lithium-containing lithium composite transition metal oxide positive electrode active material having a high content in a single particle form even at a relatively low undercalcination temperature.

Another problem to be solved by the present invention is to provide a single particle of a lithium composite transition metal oxide positive electrode active material containing a high content of nickel formed by the above-described manufacturing method.

In order to solve the above-described technical problem, the method for producing a single particle of a lithium composite transition metal oxide positive electrode active material containing a high content of nickel according to the first embodiment of the present invention,

(S1) preparing a hollow composite transition metal precursor having a hollow particle shape comprising a hollow core and a shell surrounding the core, and having a nickel content of 80 mol% or more in the total transition metal; and

(S2) The hollow composite transition metal precursor is mixed with a lithium raw material and calcined at a temperature of 800 to 870° C., but under calcined until the particles grown by the calcination are popped in the form of single particles. It includes the step of preparing a composite transition metal oxide in the form of.

According to the second embodiment of the present invention, in the manufacturing method according to the first embodiment, the hollow composite transition metal precursor having a nickel content of 80 mol% or more may be a nickel-manganese-cobalt precursor.

According to a third embodiment of the present invention, in any one or more embodiments of the first embodiment or the second embodiment, the average density of the shell part may be 1.3 g/cm ³ or more, and more preferably, the density of the shell part is 1.3 g/cm 3 or more. Preferably, it may be 1.7 g/cm ³ or more.

According to a fourth embodiment of the present invention, in any one or more embodiments of the first to third embodiments, the average diameter of the core portion of the hollow composite transition metal precursor is 1 to 8 μm, and the shell portion The average thickness may be 1 to 8 μm.

According to a fifth embodiment of the present invention, in at least one embodiment of the first to fourth embodiments, the lithium raw material is at least one selected from the group consisting of lithium hydroxide, lithium hydroxide hydrate, and lithium carbonate. can

According to the sixth embodiment of the present invention, in any one or more embodiments of the first to fifth embodiments, the undercalcination temperature of (S2) may be 830 to 850 °C.

According to the seventh embodiment of the present invention, in any one or more embodiments of the first to sixth embodiments, the average particle diameter of the single particles of the high content nickel-containing lithium composite transition metal oxide positive electrode active material is 2 to 9 μm.

According to the eighth embodiment of the present invention, in any one or more embodiments of the first to seventh embodiments, the single particles of the lithium composite transition metal oxide positive electrode active material containing a high content of nickel are represented by the following formula (1) can

<Formula 1>

Li _x [Ni _y Co _z Mn _w ]O ₂

In Formula 1,

0.8≤x≤1.5, 0.8≤y<1, 0<z<0.1, 0<w<0.1, and y+z+w=1.

According to the manufacturing method of the present invention, it is possible to easily manufacture single particles of a lithium-containing lithium composite transition metal oxide positive electrode active material having a high content in the form of single particles even at a relatively low undercalcination temperature.

Therefore, the single particles of the lithium composite transition metal oxide positive electrode active material containing high nickel content formed according to the above-described manufacturing method are single particles as the positive electrode active material made of the lithium composite transition metal oxide containing high nickel content suitable for high-capacity batteries, 1 Since the secondary particles are structurally more stable than the positive active material in the form of agglomerated secondary particles, deterioration of battery characteristics can be improved when applied to a battery.

1 is a cross-sectional SEM photograph of particles formed by calcining a hollow composite transition metal precursor prepared according to Example 1 of the present invention.
2 is a cross-sectional SEM photograph of particles formed by calcining the seed-equipped composite transition metal precursor used in Comparative Example 1 of the present invention.
3 is a SEM photograph of single particles of a nickel-containing lithium composite transition metal oxide positive electrode active material prepared according to Example 1 of the present invention.
4 is a SEM photograph of the nickel-containing lithium composite transition metal oxide positive electrode active material particles prepared according to Comparative Example 1 of the present invention.
5 is an SEM photograph of single particles of a nickel-containing lithium composite transition metal oxide positive electrode active material prepared according to Comparative Example 2 of the present invention.

Hereinafter, the present invention will be described in detail. The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Hereinafter, a method for manufacturing a single particle of a lithium composite transition metal oxide positive electrode active material containing nickel having a high content according to the present invention will be described.

According to the method for manufacturing single particles of a high-content nickel-containing lithium composite transition metal oxide positive electrode active material according to the first embodiment of the present invention, first, a hollow particle shape comprising a core part with an empty space and a shell part surrounding the core part and prepare a hollow composite transition metal precursor having a nickel content of 80 mol% or more among the total transition metals (S1).

The manufacturing method of the hollow composite transition metal precursor is exemplified as follows.

First, a transition metal hydroxide is formed through a precipitation reaction using a transition metal aqueous solution, an ammonium ion-containing solution, and a basic aqueous solution in a reactor. The temperature of the aqueous solution before the reaction is preferably adjusted to be 30 °C or more and 50 °C or less in order to form a hollow precursor with suppressed nuclear growth.

The transition metal aqueous solution is an aqueous solution containing at least one or more transition metal raw materials such as nickel-containing raw materials and other manganese-containing raw materials and cobalt-containing raw materials. For example, nickel-containing raw materials include nickel-containing acetate, Nitrate, sulfate, halide, sulfide, hydroxide, oxide or oxyhydroxide, etc., specifically, Ni(OH) ₂ , NiO, NiOOH, NiCO ₃ ·2Ni(OH) ₂ ·4H ₂ O, NiC ₂ O ₂ · 2H ₂ O, Ni(NO ₃ ) ₂ ·6H ₂ O, NiSO ₄ , NiSO ₄ ·6H ₂ O, fatty acid nickel salt, nickel halide, or a combination thereof, or a combination thereof, but is not limited thereto. The cobalt-containing raw material may be cobalt-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, or oxyhydroxide, and specifically, Co(OH) ₂ , CoOOH, Co(OCOCH ₃ ) ₂ ∙ 4H ₂ O, Co(NO ₃ ) ₂ ㆍ6H ₂ O, CoSO ₄ , Co(SO ₄ ) ₂ ㆍ7H ₂ O, or a combination thereof, but is not limited thereto. The manganese-containing raw material may be, for example, manganese-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, oxyhydroxide, or a combination thereof, specifically Mn ₂ O ₃ , MnO ₂ , Mn ₃ O manganese oxides such as ₄ ; manganese salts such as MnCO ₃ , Mn(NO ₃ ) ₂ , MnSO ₄ , manganese acetate, dicarboxylic acid manganese salt, manganese citrate, fatty acid manganese salt; It may be manganese oxyhydroxide, manganese chloride, or a combination thereof, but is not limited thereto.

The ammonium ion-containing solution may include one or more selected from NH ₄ OH, (NH ₄ ) ₂ SO ₄ , NH ₄ NO ₃ , NH ₄ Cl, CH ₃ COONH ₄ , and NH ₄ CO ₃ . In this case, as the solvent, water or a mixture of water and an organic solvent that can be uniformly mixed with water (specifically, alcohol, etc.) and water may be used.

The basic aqueous solution may include at least one selected from NaOH, KOH, and Ca(OH) ₂ , and as the solvent, water or a mixture of water and an organic solvent that can be uniformly mixed with water (specifically, alcohol, etc.) and water will be used. can

When preparing the hollow composite transition metal precursor, deionized water is put into the reactor, an inert gas is purged into the reactor to remove dissolved oxygen in the water, and the inside of the reactor is created in a non-oxidizing atmosphere, and then an ammonium cation complex forming agent and a basic aqueous solution are added. It can be carried out after adjusting the pH in the reactor by adding up to a certain volume of the reactor.

In order to prepare a hollow precursor in which the nucleation of transition metal hydroxide particles is suppressed, it may be carried out at pH 8 to 11 or less, specifically, at pH 8 to pH 9 or less. If the pH is out of the above range, particle nuclei may be formed and hollow particles may not be formed. In addition, it can help to make a hollow precursor by lowering the initial RPM and reducing the reaction time to less than 30 minutes.

In order to increase the density during the growth of the shell part of the transition metal hydroxide particles, it may be carried out at pH 11 to 13, specifically, at pH 12 or more and less than pH 13. When the pH is within the above range, new particle nuclei are hardly generated, and hollow particles having a high density of shell particles can be grown.

The average diameter of the core portion of the hollow composite transition metal precursor may be 1 to 8 μm, and the average thickness of the shell portion may be 1 to 8 μm, but is not limited thereto.

It is preferable that the average density of the shell part is 1.3 g/cm ³ or more. When the density of the shell part is 1.3 g/cm ³ or more, the composite transition metal precursor particles grow and pop well even at a low undercalcination temperature, so that single particles are further formed. it gets easier In this respect, the average density of the shell portion is more preferably 1.7 g/cm ³ or more.

The hollow composite transition metal precursor having the nickel content of 80 mol% or more may be, for example, a nickel-manganese-cobalt precursor, and the nickel-manganese-cobalt precursor may be, in particular, nickel manganese cobalt hydroxide. In addition, in addition to nickel, manganese, and cobalt, a doped metal material for improving stability and physical properties of the positive electrode active material may be further included. These doped metal materials include W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, In, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, It may be at least one element selected from the group consisting of Mg, B, and Mo.

Then, the hollow composite transition metal precursor is mixed with a lithium raw material and calcined at a temperature of 800 to 870° C., but the particles grown by the calcination are over-baked until they are popped into a single particle form. A composite transition metal oxide of (S2) is prepared.

When the present inventors use a hollow composite transition metal precursor without a seed (core) having a relatively low density when preparing a single particle type high content of nickel-containing lithium composite transition metal oxide positive electrode active material, the growth by firing The present invention was completed after confirming that the temperature for under-calcining to form single particles can be lowered until the particles are popped in the form of single particles. Here, popping means that the primary particles are grown by firing and the particles are separated from each other to form single particles. Under-firing means that the firing is carried out until the popping is made. By lowering the under-calcination temperature, it is possible to manufacture a single-particle type lithium composite transition metal oxide cathode active material with a high content of nickel, thereby improving the deterioration of the cathode active material due to high-temperature under-firing.

That is, when the under-calcination temperature is lowered when under-calcining using composite transition metal precursor particles including a seed in the core portion, the composite transition occurs due to a seed portion having a relatively lower density than the shell portion of the composite transition metal precursor particle. Since the secondary metal particles do not grow well, the particles are not well popped, so that it is difficult to form single particles, and the seed portion of the composite transition metal precursor particles remains as it is. On the other hand, according to the present invention, when the hollow composite transition metal precursor particles composed only of the shell portion having a relatively high density are under-calcined, the shell portion grows well even when under-calcining at a lower temperature than when using conventional composite transition metal precursor particles. By being popped, single particles are easily formed.

As the lithium raw material, various lithium raw materials known in the art may be used without limitation, for example, lithium-containing carbonate (eg, lithium carbonate, etc.), lithium-containing hydrate (eg, lithium hydroxide hydrate). (LiOH·H ₂ O), etc.), lithium-containing hydroxides (such as lithium hydroxide), lithium-containing nitrates (such as lithium nitrate (LiNO ₃ ), etc.), lithium-containing chlorides (such as lithium chloride ( LiCl), etc.) may be used. Preferably, the lithium raw material may be at least one selected from the group consisting of lithium hydroxide, lithium hydroxide hydrate, and lithium carbonate.

The undercalcination temperature of (S2) is a temperature of 800 to 870 °C. If the under-calcination temperature is less than 870 ℃, the particles grown by sintering are popped in the form of single particles, making it difficult to form single-particles, and if it exceeds 870 ℃, capacity drop will occur. Preferably, it is particularly easy to form single particles while the temperature is relatively low that the under-calcination temperature is 830 to 850°C.

As described above, the under-firing time proceeds until the particles growing by firing are popped and formed into single particles, for example, 5 to 20 hours may be fired. If necessary, as is well known, the plasticizing may be performed at a temperature lower than the under-firing temperature before the under-firing.

The particles formed after over-calcination may be pulverized, classified, and washed as necessary to finally prepare single particles of a lithium composite transition metal oxide positive electrode active material containing nickel having a high content.

The lithium composite transition metal oxide of the single particles of the positive active material prepared by the above method is an oxide of a composite transition metal and nickel containing at least one transition metal such as high content nickel, manganese, and cobalt, and more specifically, the following It may be one represented by the formula (1).

<Formula 1>

Li _x [Ni _y Co _z Mn _w ]O ₂

In Formula 1,

0.8≤x≤1.5, 0.8≤y<1, 0<z<0.1, 0<w<0.1, and y+z+w=1.

When a doping element is further included, it becomes y+z+w<.

Here, “a single particle type cathode active material made of lithium composite transition metal oxide” means that the positive active material particles made of all lithium composite transition metal oxides are single particles, not secondary particles, or at least 80% or more It means single particles The average size (D50) of the single particles may be 2.0 ~ 9.0 um, but is not limited thereto.

The single particles of the positive electrode active material made of the high-content lithium composite transition metal oxide prepared in this way can be coated on the positive electrode current collector and used in the following way.

For example, the positive electrode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, fired carbon, or carbon, nickel on the surface of aluminum or stainless steel. , titanium, silver, or the like surface-treated may be used. In addition, the positive electrode current collector may typically have a thickness of 3 to 500 μm, and may increase the adhesion of the positive electrode active material by forming fine irregularities on the surface of the current collector. For example, it may be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven body.

The positive electrode active material layer may optionally include a conductive material and, if necessary, a binder together with the positive active material. In this case, the positive active material may be included in an amount of 80 to 99% by weight, more specifically 85 to 98.5% by weight, based on the total weight of the positive active material layer. When included in the above content range, excellent capacity characteristics may be exhibited.

The conductive material is used to impart conductivity to the electrode, and in the configured battery, it can be used without any particular limitation as long as it does not cause chemical change and has electronic conductivity. Specific examples include graphite such as natural graphite and artificial graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, summer black, and carbon fiber; metal powders or metal fibers, such as copper, nickel, aluminum, and silver; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like, and one or a mixture of two or more thereof may be used. The conductive material may be included in an amount of 0.1 to 15% by weight based on the total weight of the positive electrode active material layer.

The binder serves to improve adhesion between the positive active material particles and adhesion between the positive active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylalcohol, polyacrylonitrile, carboxymethylcellulose Woods (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, and any one of them or a mixture of two or more thereof may be used. The binder may be included in an amount of 0.1 to 15% by weight based on the total weight of the positive electrode active material layer.

The positive electrode may be manufactured according to a conventional positive electrode manufacturing method except for using the above positive electrode active material. Specifically, the positive electrode active material and, optionally, a composition for forming a positive electrode active material layer prepared by dissolving or dispersing a binder and a conductive material in a solvent may be coated on a positive electrode current collector, and then dried and rolled.

Alternatively, the positive electrode may be manufactured by casting the composition for forming the positive electrode active material layer on a separate support and then laminating a film obtained by peeling it from the support on the positive electrode current collector.

The positive electrode manufactured by the above method may be used in an electrochemical device such as a battery or a capacitor, and more specifically, may be used in a lithium secondary battery.

Hereinafter, examples will be given to describe the present invention in detail. However, the embodiment according to the present invention may be modified in various other forms, and the scope of the present invention should not be construed as being limited to the embodiment described in detail below. The embodiments of the present invention are provided to more completely explain the present invention to those of ordinary skill in the art.

<Evaluation method>

Measurement of average particle size, etc.

The average density of the shell portion of the hollow composite transition metal precursor was measured with a helium piconometer.

The average particle diameter (D50) of single particles is defined as the particle diameter corresponding to 50% of the cumulative volume in the particle size distribution curve. After introducing and irradiating an ultrasonic wave of about 28 kHz with an output of 40 W, the average particle diameter (D50) corresponding to 50% of the volume accumulation in the measuring device was calculated.

On the other hand, the average diameter of the core part and the average thickness of the shell part of the mid-curved composite transition metal precursor were obtained by preparing the fired particles according to the indirect method described below, then cutting the particles and using a scanning electron microscope (SEM). The average diameter of the core part and the average thickness of the shell part were measured.

Initial dose evaluation

The prepared single-particle cathode material was finally manufactured by manufacturing a coin half cell (CHC) and performance evaluation was performed. The cathode material electrode prepared prior to evaluation was prepared by coating the cathode material powder with a conductive material and a binder on Al foil. When manufacturing the electrode, the ratio of the positive electrode active material, PvdF binder, and carbon black is 97.5: 1.5: 1.0, dispersed in NMP solution, mixed using a thinky mixer to prepare an electrode slurry, and then added to the Al current collector. was applied. Then, it was rolled by a roll press to prepare a positive electrode.

In addition, a coin half cell was manufactured using lithium metal as a counter electrode.

The initial charging and discharging capacity of the coin half-cell prepared as described above was measured at room temperature under the conditions of a final charging voltage of 4.25V, a final discharging voltage of 3V, and 0.2C/0.2C.

Example 1

Li[Ni _0.92 Co _0.04 Mn _0.04 ]O ₂ A positive active material single particle represented by the target was prepared as follows.

NiSO ₄ , CoSO ₄ , and MnSO ₄ were mixed in water in an amount such that the molar ratio of nickel:cobalt:manganese was 92:4:4 to prepare an aqueous transition metal solution.

A vessel containing the transition metal aqueous solution, a vessel containing an aqueous solution of NaOH having a concentration of 20% by weight, and a vessel containing an aqueous NH4OH solution were respectively connected to a batch reactor (10L).

Then, after adding deionized water to the reactor, nitrogen gas was purged into the reactor at a rate of 2 L/min to remove dissolved oxygen in the water, and a non-oxidizing atmosphere was created in the reactor. After the NaOH aqueous solution and NH ₄ OH aqueous solution were added, the mixture was stirred at 30° C. at a stirring speed of 200 rpm, and the pH in the reactor was adjusted to 8.

Thereafter, the transition metal aqueous solution was introduced into the reactor at a rate of 0.8L/hr, NaOH aqueous solution 0.54L/hr, and NH ₄ OH aqueous solution 0.06L/hr, and the precipitation reaction was carried out at pH 13 for 40 hours, the composite transition metal Hydroxide was prepared.

The average density of the shell portion of the obtained hollow composite transition metal precursor was 1.7 g/cm ³ .

The hollow composite transition metal precursor obtained by the above method was mixed with lithium hydroxide as a lithium raw material, put into an alumina crucible, and the temperature was raised to 830 ° C in an atmosphere with an oxygen concentration of 95 vol% while maintaining the temperature for 10 hours. After calcination and cooling, the particles were pulverized to break necking between particles.

Subsequently, as a result, single particles of the positive electrode active material of the target composition formula ((average size of single particles (D50) = 5 um) were obtained.

Meanwhile, in the present specification, the average diameter of the core part and the average thickness of the shell part of the hollow composite transition metal precursor were measured by the following indirect method and are defined as follows. The hollow composite transition metal precursor was mixed with a lithium raw material according to the manufacturing method described above and calcined, but the calcination temperature was raised to 760 °C and calcined for 10 hours. 1 is a cross-sectional SEM photograph of particles formed by sintering a hollow composite transition metal precursor in this way. The average diameter of the core part was 4 um, and the average thickness of the shell part was 2.0 um.

Example 2

Li[Ni _0.92 Co _0.04 Mn _0.04 ]O ₂ A positive active material single particle represented by the target was prepared as follows.

NiSO ₄ , CoSO ₄ , and MnSO ₄ were mixed in water in an amount such that the molar ratio of nickel:cobalt:manganese was 92:4:4 to prepare an aqueous transition metal solution.

A vessel containing the transition metal aqueous solution, a vessel containing an aqueous solution of NaOH having a concentration of 20% by weight, and a vessel containing an aqueous NH4OH solution were respectively connected to a batch reactor (10L).

Then, after adding deionized water to the reactor, nitrogen gas was purged into the reactor at a rate of 2 L/min to remove dissolved oxygen in the water, and a non-oxidizing atmosphere was created in the reactor. After the NaOH aqueous solution and NH ₄ OH aqueous solution were added, the mixture was stirred at 30° C. at a stirring speed of 200 rpm, and the pH in the reactor was adjusted to 8.

Thereafter, the transition metal aqueous solution was introduced into the reactor at a rate of 0.8 L/hr, NaOH aqueous solution 0.54 L/hr, and NH ₄ OH aqueous solution at a rate of 0.06 L/hr, and the precipitation reaction was performed at pH 12 for 40 hours, the composite transition metal Hydroxide was prepared.

The average density of the shell portion of the hollow composite transition metal precursor was 1.55 g/cm ³ .

Using this, it was carried out in the same manner as in Example 1 except that the firing temperature was changed to 850 °C to obtain single positive active material particles ((average size of single particles (D50) = 5.3 um).

On the other hand, the average diameter of the core part of the hollow composite transition metal precursor measured indirectly by the above-described method was 4 um, and the average thickness of the shell part was 2.5 um.

Comparative Example 1

NiSO ₄ , CoSO ₄ , and MnSO ₄ were mixed in water in an amount such that the molar ratio of nickel:cobalt:manganese was 92:4:4 to prepare an aqueous transition metal solution.

A vessel containing the transition metal aqueous solution, a vessel containing an aqueous NaOH solution having a concentration of 25% by weight, and a vessel containing an aqueous NH ₄ OH solution were respectively connected to a batch reactor (10L).

Then, the reactor was purged with deionized water nitrogen gas at a rate of 2 L/min to remove dissolved oxygen in the water, and a non-oxidizing atmosphere was created in the reactor. Thereafter, an aqueous NaOH solution and an aqueous NH4OH solution were added, followed by stirring at a stirring speed of 1000 rpm at 60° C. to adjust the pH in the reactor to 12.5.

Thereafter, the transition metal aqueous solution was put into the reactor at a rate of 1.7L/hr, NaOH aqueous solution 0.54L/hr, and NHOH aqueous solution 0.06L/hr, and the precipitation reaction was carried out at pH 10.5 for 40 hours to obtain a complex transition metal hydroxide prepared.

The obtained composite transition metal precursor was calcined in the same manner as in Example 1, and as a result of checking the particles, it can be confirmed that the core portion is filled as shown in FIG. 2 .

This precursor was used, except that the firing temperature was changed to 850° C., and the same procedure as in Example 1 was performed.

Comparative Example 2

It was carried out in the same manner as in Comparative Example 1, except that the firing temperature was changed to 900°C.

Precursor type underfiring temperature
(℃) Whether single particles are formed Initial capacity (mA/g)
charge/discharge Example 1 hollow precursor 830 O 236/206 Example 2 hollow precursor 850 O 234/204 Comparative Example 1 seed
precursor 850 X 235/200 Comparative Example 2 seed
precursor 900 O 224/195

From the results in Table 1, it can be seen that in Examples 1 and 2, single particles were well formed even at a relatively low under-calcination temperature. In particular, in Example 1, single particles were well formed even at a lower temperature by using a hollow precursor having a higher density of the shell portion than in Example 2 (see FIG. 3).

On the other hand, according to Comparative Example 1, it was confirmed that single particles were not formed and agglomerated even at 850° C. during over-calcination using a conventional seed-equipped precursor ( FIG. 4 ), and for this reason, according to Comparative Example 2, the under-calcination temperature was set at 900 ° C. A single particle was formed only when it was raised to .

However, the single particles of Comparative Example 2 also remained agglomerated without being formed as single particles in the seed portion (the portion indicated by a circle) as confirmed in FIG. 5 .

Claims (10)

(S1) preparing a hollow composite transition metal precursor having a hollow particle shape comprising a hollow core and a shell surrounding the core, and having a nickel content of 80 mol% or more in the total transition metal; and
(S2) The hollow composite transition metal precursor is mixed with a lithium raw material and calcined at a temperature of 800 to 870° C., but under calcined until the particles grown by the calcination are popped in the form of single particles. A method for preparing single particles of a lithium composite transition metal oxide positive electrode active material containing a high content of nickel, comprising the step of preparing a composite transition metal oxide of the form. According to claim 1,
The hollow composite transition metal precursor having the nickel content of 80 mol% or more is a nickel-manganese-cobalt precursor. According to claim 1,
The average density of the shell portion is 1.3 g/cm ³ or more. According to claim 1,
The average density of the shell part is 1.7 g/cm ³ or more. The method of claim 1,
The average diameter of the core portion of the hollow composite transition metal precursor is 1 to 8 μm, and the average thickness of the shell portion is 1 to 8 μm Preparation of high-content nickel-containing lithium composite transition metal oxide positive electrode active material single particles Way. The method of claim 1,
The lithium raw material is a method of manufacturing a single particle of a lithium composite transition metal oxide positive electrode active material containing a high content of nickel, characterized in that at least one selected from the group consisting of lithium hydroxide, lithium hydroxide hydrate and lithium carbonate. The method of claim 1,
The method of manufacturing a single particle of a lithium composite transition metal oxide positive electrode active material containing a high content of nickel, characterized in that the under-calcination temperature of (S2) is 830 to 850 °C. According to claim 1,
The method of manufacturing a single particle of a lithium composite transition metal oxide positive electrode active material containing a high content of nickel, characterized in that the average particle diameter of the single particle of the high content nickel-containing lithium composite transition metal oxide positive electrode active material is 2 to 9 um. According to claim 1,
The lithium composite transition metal oxide containing nickel of high content is a method of manufacturing a lithium composite transition metal oxide positive electrode single particle containing high content of nickel, characterized in that represented by the following formula (1):
<Formula 1>
Li _x [Ni _y Co _z Mn _w ]O ₂
In Formula 1,
0.8≤x≤1.5, 0.8≤y<1, 0<z<0.1, 0<w<0.1, and y+z+w=1. [10] A single particle of a lithium composite transition metal oxide positive electrode active material containing a high content of nickel formed according to the method of any one of claims 1 to 9.

Images