KR20220064885A - Positive active material and method for preparing the same - Google Patents

Abstract

The present invention relates to a cathode active material and a method of preparing the same, and more specifically, to a method of directly preparing a cathode active material from nickel raw material powder of relatively low purity compared to a material raw of a coprecipitation method extracted from nickel ore Instead of dissolving and using a high-purity nickel raw material as in a conventional coprecipitation method and an active material prepared thereby.

Description

Positive active material and manufacturing method thereof

The present invention relates to a cathode active material and a method for manufacturing the same, and more specifically, from a nickel raw material powder of relatively low purity compared to a co-precipitation raw material extracted from nickel ore instead of dissolving and using a high-purity nickel raw material as in the conventional co-precipitation method The present invention relates to a method for directly manufacturing a positive electrode active material and a positive electrode active material prepared thereby.

A battery stores electric power by using a material capable of electrochemical reaction between the anode and the cathode. A representative example of such a battery is a lithium secondary battery that stores electrical energy by a difference in chemical potential when lithium ions are intercalated/deintercalated in a positive electrode and a negative electrode.

The lithium secondary battery is manufactured by using a material capable of reversible intercalation/deintercalation of lithium ions as a positive electrode and a negative electrode active material, and filling an organic electrolyte solution or a polymer electrolyte solution between the positive electrode and the negative electrode.

A lithium composite oxide is used as a cathode active material for a lithium secondary battery. For example, composite oxides such as LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , and LiMnO ₂ are being studied. Recently, a part of nickel among lithium composite oxides is Co , Mn and/or a form substituted with a metal such as Al has been proposed.

On the other hand, as the technology develops, the demand for lithium secondary batteries, including electric vehicles, is rapidly increasing, and in the related industry, the demand for cost reduction of lithium secondary batteries and various materials used in the lithium secondary batteries is also increasing. am.

In particular, since the positive electrode active material occupies the largest portion of the price of the lithium secondary battery, if the manufacturing cost of the positive electrode active material can be lowered, the price of the lithium secondary battery is also expected to decrease.

For example, conventionally, a co-precipitation method is used to synthesize a precursor of nickel or a lithium composite oxide containing nickel and other elements.

At this time, the co-precipitation method is pointed out as a cause of generating a large amount of wastewater and increasing the manufacturing cost of the cathode active material as well as environmental pollution due to complicated process steps. For example, it is known that 99,000 liters of process water are used to synthesize 6,500 kg of nickel-cobalt-manganese three-component lithium composite oxide, and the raw material cost of the total manufacturing cost of lithium composite oxide reaches almost 50%.

In addition, since the nickel raw material used in the co-precipitation method requires a very high degree of purity, a relatively inexpensive low-purity (eg, class 2 grade) raw material such as nickel oxide powder is used as the raw material of the co-precipitation method. There is a limit to what it is difficult to do.

Accordingly, recently, a technique for reducing the manufacturing cost of a positive electrode active material by recycling a waste positive electrode active material recovered from a lithium secondary battery that has reached the end of its useful life has been introduced. However, a technique for preparing a lithium composite oxide for a positive electrode active material using a relatively low-purity nickel raw material by a method other than the co-precipitation method has not yet been specifically known.

Korean Patent Publication No. 10-2016-0118307

In the lithium secondary battery market, while the growth of lithium secondary batteries for electric vehicles is playing a leading role in the market, the demand for positive electrode active materials used in lithium secondary batteries is also continuously increasing. Accordingly, in recent years, the demand for cost reduction of the positive electrode active material, which accounts for the largest proportion of the manufacturing cost of the lithium secondary battery, is also gradually increasing.

In order to meet the needs of the market, the present invention does not use the co-precipitation method when synthesizing the positive electrode active material, particularly when synthesizing the precursor of the lithium composite oxide constituting the positive electrode active material. An object of the present invention is to provide a method for manufacturing a positive electrode active material capable of solving a problem of increase in unit cost.

Another object of the present invention is to provide a method of manufacturing a cathode active material capable of reducing raw material costs by using a relatively inexpensive low-purity nickel raw material powder compared to a high-purity nickel raw material used in the co-precipitation method.

In particular, the present invention does not use the co-precipitation method and, despite the fact that it is manufactured using a relatively low-purity nickel raw material, uses a high-purity nickel raw material to achieve a similar level of electricity to that of a cathode active material synthesized by a conventional co-precipitation method. An object of the present invention is to provide a method for manufacturing a positive electrode active material capable of exhibiting chemical properties and stability.

Another object of the present invention is to provide a positive electrode active material manufactured according to the manufacturing method defined herein.

The objects of the present invention are not limited to the above-mentioned objects (eg, for an electric vehicle), and other objects and advantages of the present invention not mentioned can be understood by the following description and can be will be understood more clearly. It will also be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof indicated in the claims.

According to one aspect of the present invention, (a) mixing at least one nickel raw material powder containing a transition metal with a solvent to prepare a slurry in which the nickel raw material powder is dispersed in the solvent; (b) grinding the nickel raw material powder in the slurry; (c) preparing a precursor by spray-drying the slurry in which the nickel raw material powder is pulverized; and (d) mixing at least one sub raw material including the precursor, the lithium-containing raw material and the dopant and then heat-treating the mixture to obtain a lithium composite oxide;

In step (a), the nickel raw material powder in the solvent is present in a substantially undissolved state, that is, in a powder form.

The nickel raw material powder used in step (a) is nickel metal powder, nickel oxide, nickel sulfide, nickel hydroxide, nickel ingot, nickel pellet, nickel briquette, nickel mat, nickel scrap, ferronickel, nickel pig iron and nickel It may include at least one nickel raw material powder selected from concentrates.

In one embodiment, the step (b) may be repeatedly performed using different bead sizes to form a precursor having a predetermined shape through the spray drying of step (c) described below.

The precursor may include spherical secondary particles formed by granulation or aggregation of a plurality of primary particles.

In one embodiment,

The lithium composite oxide may be represented by Formula 1 or Formula 2 below.

[Formula 1]

Li _x Ni _1-y M _y O _2-z X _z

(here,

M is Mn, Co, B, Ba, Ce, Hf, Ta, Cr, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, Sr, At least one selected from Ge, Nd, Gd and Cu,

X is selected from F, S and P,

0.5≤x≤1.5, 0≤y≤0.50, 0≤z≤2)

[Formula 2]

Li _a Ni _1-(b+c+d) Co _b M1 _c M2 _d O _e

(here,

M1 is at least one selected from Mn and Al,

M2 is Mn, B, Ba, Ce, Hf, Ta, Cr, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, Sr, Ge, At least one selected from Nd, Gd and Cu;

M1 and M2 are different from each other,

0.50≤a≤1.50, 0≤b≤0.20, 0≤c≤0.10, 0≤d≤0.05, 1.0≤e≤2.0)

According to the present invention, since the co-precipitation method is not used when synthesizing the positive electrode active material, particularly when synthesizing the precursor of the lithium composite oxide constituting the positive electrode active material, the problem of environmental pollution and increased manufacturing cost caused by the use of the co-precipitation method can be solved. there is.

In particular, according to the present invention, it is possible to reduce the raw material cost by using a relatively inexpensive low-purity nickel raw material powder compared to the high-purity nickel raw material used in the co-precipitation method.

In addition, according to the present invention, it is possible to prepare a positive electrode active material capable of exhibiting electrochemical properties and stability at a level similar to that of a positive electrode active material synthesized by a conventional co-precipitation method using a high-purity nickel raw material. Cost reduction of the used lithium secondary battery can be achieved effectively.

In addition to the above-described effects, the specific effects of the present invention will be described together while describing specific details for carrying out the invention below.

1 to 9 show SEM images of precursors and positive electrode active materials of Examples 1 to 3 and Comparative Examples 1 to 6;

In order to better understand the present invention, certain terms are defined herein for convenience. Unless defined otherwise herein, scientific and technical terms used herein shall have the meanings commonly understood by one of ordinary skill in the art. Also, unless the context specifically dictates otherwise, it is to be understood that a term in the singular includes its plural form as well, and a term in the plural form also includes its singular form.

Hereinafter, a method for manufacturing a positive electrode active material for a lithium secondary battery according to the present invention, a positive electrode including a positive electrode active material manufactured according to the manufacturing method, and a lithium secondary battery using the positive electrode will be described in more detail.

Method of manufacturing a cathode active material for a lithium secondary battery

According to one aspect of the present invention, (a) mixing at least one raw material powder containing a transition metal with a solvent to prepare a slurry in which the nickel raw material powder is dispersed in the solvent; (b) the nickel in the slurry pulverizing the raw material powder, (c) preparing a precursor by spray-drying the slurry in which the nickel raw material powder is pulverized, and (d) mixing the precursor and a lithium-containing raw material and heat-treating to obtain a lithium composite oxide There is provided a method of manufacturing a positive electrode active material comprising the step of:

The nickel raw material powder may be referred to by various names depending on the purity grade, shape and/or impurity content, etc., but for example, nickel metal powder, nickel oxide, nickel sulfide, nickel hydroxide, nickel ingot, nickel pellets, nickel Briquettes, nickel mats, nickel scrap, ferronickel, nickel pig iron and nickel concentrates. In addition, the nickel concentrate may be nickel limonite, nickel laterite and/or nickel saprolite.

The nickel raw material powder used herein refers to the nickel raw material powder in the stage before complete purification after extraction from nickel ore, unlike purified nickel (for example, purified nickel sulfate with a purity of 99.8% or more) used in the conventional co-precipitation method. , so-called class 1 and/or class 2 nickel raw material powder.

The grade of the nickel raw material powder is given according to the nickel content in the raw material powder, and in general, when the nickel content is 99% or more, it corresponds to a class 1 grade, and when the nickel content is less than 99%, it corresponds to a class 2 grade.

The nickel raw material powder used herein may have a purity of 50% or more, preferably 70% or more, more preferably 90% or more of the nickel raw material powder.

In order to reduce the content of impurities in the cathode active material, which is the final product, it is preferable that the purity of nickel in the nickel raw material powder is high. However, as the relatively high purity nickel is used, the unit price of the nickel raw material powder increases, eventually achieving cost reduction of the cathode active material It may be difficult to achieve the technical problem of the present invention.

Accordingly, in the present application, a nickel raw material powder having a relatively low purity compared to purified nickel used in a conventional co-precipitation method may be used within a range that does not particularly reduce the electrochemical properties and stability of the positive electrode active material, which is the final product.

That is, in step (a) of the present application, nickel metal powder, nickel oxide, nickel sulfide, nickel hydroxide, nickel ingot, nickel pellet, nickel briquette, nickel mat, nickel scrap, ferronickel, nickel pig iron and nickel as exemplified above in step (a) At least one nickel raw material powder selected from concentrates may be used, and among the nickel raw material powders not mentioned above, a nickel raw material powder having a relatively low purity compared to purified nickel used in a conventional co-precipitation method may be used.

In addition, the nickel raw material powder used in step (a) of the present application will not contain at least nickel oxide or nickel hydroxide synthesized through a co-precipitation method.

When the average particle diameter of the nickel raw material powder is excessively large, the process of pulverizing the nickel raw material powder to have an average particle diameter of 1 to 200 μm before step (a) may be further included. In addition, a process of pulverizing the nickel raw material powder and then spray-drying may be additionally performed. As such, it can contribute to synthesizing a positive electrode active material having a more uniform shape by controlling the average particle diameter and shape of the nickel raw material powder before preparing the slurry in step (a).

To pulverize the nickel raw material powder, a ball mill, a beads mill (using beads commonly used to pulverize metallic raw materials such as Al beads, Fe beads or Zr beads), vibratory mill, attritor mill, air jet mill, disk mill Alternatively, a dry or wet dispersion mill such as an air classifier mill may be used.

The nickel raw material powder is mixed with a solvent to form a slurry. In the slurry, the nickel raw material powder, particularly the nickel raw material powder, is different from the conventional co-precipitation method in that it is not substantially dissolved in the solvent, that is, it exists in the form of a powder.

The solvent is not particularly limited as long as it is a solvent capable of creating an environment in which steps (b) and (c) to be described later can be performed without dissolving the nickel raw material powder, particularly the nickel raw material powder. For example, as the solvent, deionized water, distilled water, alcohol (ethyl alcohol, isopropyl alcohol), acetone, an aqueous acid solution, an aqueous alkali solution, or any mixture thereof may be used.

In another embodiment, the slurry of step (a) is the nickel raw material powder, the solvent and Mn, Co, B, Ba, Ce, Hf, Ta, Cr, F, Mg, Al, Cr, V, Ti , Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, Sr, Ge, Nd, Gd and Cu to be prepared by mixing at least one sub raw material containing a dopant selected from can

In this case, the sub raw material may be provided in at least one form selected from sulfate, carbonate, nitrate, acetate, chloride, hydrate, and oxide.

In addition, preferably, the sub raw material is also provided in the form of a powder, and may exist in a state that is not substantially dissolved in the solvent. Accordingly, the present application does not require a large amount of process water for dissolving the transition metal-containing raw material powder as well as the nickel raw material powder, unlike the conventional co-precipitation method.

For example, when the nickel raw material powder used in step (a) further includes a sub raw material containing Co and a sub raw material containing Al other than the nickel raw material powder described above, a step (c) to be described later The precursor prepared in may be a composite oxide and/or hydroxide including Ni, Co and Al.

On the other hand, when the nickel raw material powder used in step (a) further includes a sub raw material containing Co and a sub raw material containing Mn other than the nickel raw material powder described above, in step (c) to be described later The prepared precursor may be a complex oxide and/or hydroxide including Ni, Co and Mn.

In another embodiment, the slurry of step (a) may be prepared by mixing the nickel raw material powder, the solvent, and a lithium-containing raw material.

The lithium-containing raw material includes a lithium compound capable of reacting with the nickel raw material powder to form a lithium composite oxide. As the lithium compound, lithium hydroxide, lithium carbonate, lithium nitrate or lithium acetate may be used.

The lithium compound is preferably mixed in a ratio (Li/Metal) of the number of atoms (Li) of lithium to the total number of atoms (Metal) of metal elements other than lithium in the nickel raw material powder (Li/Metal) is in the range of 0.05 to 0.5. The lithium-containing raw material induces lithiation of the nickel raw material powder by reacting with the nickel raw material powder in a process step to be described later, and at the same time as a binder for the nickel raw material powder or the nickel raw material powder and the sub raw material It can serve to improve the bonding force between particles.

In addition, in order to improve the bonding force between the particles, a binder to be described later may be used instead of the lithium-containing raw material, or a mixture of the lithium-containing raw material and the binder may be used.

Additionally, the above-described sub raw material may also be added to the mixture in which the nickel raw material powder, the solvent, and the lithium-containing raw material are mixed.

After preparing the slurry through step (a), the step of adjusting the viscosity of the slurry within the range of 5,000 to 20,000 cp may be performed. The viscosity of the slurry may be achieved by adjusting the content of the solvent in the slurry or adjusting the content of the solid content.

Since the slurry has the above-mentioned viscosity range, it is possible to shorten the condensation time during spray drying in step (c), which will be described later, and as the content of moisture lost by drying is small, it is possible to obtain a high-density precursor Do.

In the step of adjusting the viscosity of the slurry, lithium hydroxide, sodium hydroxide, carboxylic acid or a salt thereof (eg, acetic acid, acrylic acid, citric acid, ascorbic acid, formic acid, lactic acid, malic acid, malonic acid, oxalic acid, tartaric acid, polycarboxylic acid) , polycarboxylic acid sodium salt, polycarboxylic acid ammonium salt, polycarboxylic acid amine salt, carboxymethylcellulose sodium salt, etc.), saccharides (starch, monosaccharide, disaccharide, polysaccharide, dextrin, Cyclodextrin or maltodextrin, etc.), polymers (polyvinyl alcohol, polyvinyl butyral, polyacrylic acid, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrol Don, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polyethylene glycol, polypropylene, polyamideimide, polyimide, styrene-butadiene rubber, acrylated styrene-butadiene rubber, polyvinyl alcohol , sodium polyacrylate, propylene and an olefin copolymer having 2 to 8 carbon atoms, a copolymer of (meth)acrylic acid and (meth)acrylic acid alkyl ester) and/or sodium dodecylbenzene sulfonate, etc. A binder may be added. there is.

The binder strengthens the bonding force between particles so that particles do not break or collapse in a process step to be described later, so that a precursor and lithium composite oxide having a shape close to a spherical shape can be formed.

In addition, the amount of the binder may vary depending on the content of the raw material in the slurry and the molecular weight of the binder, but is preferably added in an amount of 1% or less based on the total weight of the raw material in the slurry.

Subsequently, in step (b), the step of pulverizing the nickel raw material powder in the slurry is performed. If the sub raw material is included in the slurry and the sub raw material is present in a powder form, the sub raw material may also be pulverized in step (b).

It is preferable that the pulverization process according to step (b) is performed even when a process of pulverizing or spray drying the nickel raw material powder before step (a) is involved.

In order to grind the nickel raw material powder in the slurry, a ball mill, a beads mill (using beads commonly used to grind metallic raw materials such as Al beads, Fe beads or Zr beads), vibratory mill, attritor mill, air jet mill , a dry or wet dispersion mill such as a disk mill or an air classifier mill may be used.

Step (b) may be repeatedly performed so that the nickel raw material powder, particularly, the nickel raw material powder in the slurry may have a predetermined particle size and shape.

At this time, the step (b) is preferably performed repeatedly using different bead sizes. For example, in step (b), the nickel raw material powder in the slurry is pulverized through a bead mill using beads having a first average diameter, and then in the slurry through a bead mill using beads having a second average diameter. The nickel raw material powder may be additionally pulverized. In particular, the process of pulverizing the nickel raw material powder in the slurry through a bead mill using beads having a second average diameter may be repeated at least twice or more. Here, the second average diameter is preferably smaller than the first average diameter.

As such, it is possible to obtain a raw material powder having a more uniform shape and size through repeated execution of step (b), and thus, it is possible to improve the particle strength of the cathode active material synthesized through the nickel raw material powder Do.

The particle strength of the positive active material can be confirmed, for example, by measuring the rate of change of D ₅₀ /D ₁₀ of the lithium composite oxide in the positive active material after ultrasonicating the positive active material at a frequency of 40 kHz for 60 seconds.

The average particle diameter of the raw material pulverized in step (b), particularly the nickel raw material powder, may vary depending on the average particle diameter of the nickel raw material powder used in step (a), but has a range of 0.1 μm to 40 μm. it is preferable

After the pulverization of step (b) is completed, the viscosity of the slurry is preferably in the range of 3,000 to 20,000 cp.

Since the slurry has the above-mentioned viscosity range, it is possible to shorten the condensation time during spray drying in step (c), which will be described later, and as the content of moisture lost by drying is small, it is possible to obtain a high-density precursor Do.

If the viscosity of the slurry is less than 3,000 cp, not only the condensation time during spray drying increases, but also the density of the precursor decreases as the content of moisture lost by drying increases, and there is a risk of forming a large amount of pores in the precursor there is A precursor having a low density and a large amount of pores is likely to exhibit weak particle strength. In this case, as the cathode active material collapses during charging/discharging or during storage of a lithium secondary battery using the cathode active material prepared using the precursor, the electrochemical properties of the lithium secondary battery may be lowered or the stability may be lowered.

On the other hand, when the viscosity of the slurry exceeds 20,000 cp, sufficient process efficiency cannot be achieved because the fluidity of the slurry in the spray dryer in which the spray drying of step (c) is performed is low, and the spray drying is not performed. It may be difficult to obtain a precursor with a shape close to a spherical shape prepared through the

In addition, Mn, Co, B, Ba, Ce, Hf, Ta, Cr, F, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, At least one sub raw material including a dopant selected from Y, Nb, Ga, Sn, Mo, W, P, Sr, Ge, Nd, Gd, and Cu may be additionally added.

In this case, the sub raw material may be provided in at least one form selected from sulfate, carbonate, nitrate, acetate, chloride, hydrate, and oxide. In addition, preferably, the sub raw material is also provided in the form of a powder, and may exist in a state that is not substantially dissolved in the solvent. Accordingly, the present application does not require a large amount of process water for dissolving the transition metal-containing raw material powder as well as the nickel raw material powder, unlike the conventional co-precipitation method.

In addition, a binder may be additionally added to the slurry before the spray drying of step (c). Here, the binder may be the same as the binder used in step (a) described above.

The amount of the binder input may vary depending on the content of the raw material in the slurry and the molecular weight of the binder, but is preferably added in an amount of 1% or less based on the total weight of the raw material in the slurry.

If the binder has already been added in step (a), the sum of the input amount of the binder in step (a) and the amount of the binder before step (c) is 1% based on the total weight of the raw material in the slurry It is preferable to make it become the following.

Meanwhile, before spray-drying the slurry in step (c), the temperature of the slurry is preferably adjusted within the range of 15 to 70°C. At this time, the temperature of the slurry before spray drying means the temperature of the slurry before the slurry is put into the spray dryer in which the spray drying of step (c) is performed.

When the temperature of the slurry is less than 15° C., the thermal shock applied to the particles (pulverized waste-positive electrode active material) in the slurry may be excessively large because the difference from the temperature under the environment in which the spray drying of step (c) is performed is large. there is. In this case, disintegration of particles (pulverized waste-positive electrode active material) in the slurry may be caused.

On the other hand, when the temperature of the slurry exceeds 70° C., there is a problem in that it is difficult to accurately control the viscosity of the slurry due to evaporation of a solvent in the slurry.

As described above, the raw material, in particular, the slurry in which the nickel raw material powder is pulverized may be spray-dried in step (c) to obtain a precursor.

If the nickel raw material powder used in step (a) does not include the lithium-containing raw material, the lithium-containing raw material may be added to the slurry before spray drying in the step (c). Like the lithium-containing raw material input in step (a), the lithium-containing raw material input in step (b) includes a lithium compound capable of forming a lithium composite oxide by reacting with the nickel raw material powder. As the lithium compound, lithium hydroxide, lithium carbonate, lithium nitrate or lithium acetate may be used.

The lithium compound is preferably mixed in a ratio (Li/Metal) of the number of atoms (Li) of lithium to the total number of atoms (Metal) of metal elements other than lithium in the nickel raw material powder (Li/Metal) is in the range of 0.05 to 0.5.

The lithium-containing raw material reacts with the nickel raw material powder during spray drying in step (c) to induce lithiation of the nickel raw material powder, and at the same time, the nickel raw material powder or the nickel raw material powder and the sub raw material It can serve as a binder for the particles to improve the bonding force between the particles.

In addition, in order to improve the bonding force between the particles, a binder to be described later may be used instead of the lithium-containing raw material, or a mixture of the lithium-containing raw material and the binder may be used.

The step (c) may be carried out in a spray dryer, and the spray dryer is a spray drying device capable of producing a dried precursor having a shape close to a spherical shape by spray drying the slurry in which the raw material is pulverized. Not limited. Non-limiting examples of the spray dryer include an ultrasonic atomizer, a hydraulic jet nozzle atomizer, a pneumatic jet nozzle atomizer, an ultrasonic nozzle atomizer, a filter expansion droplet generator (FEAG), or a disk type droplet generator.

The spray dryer in which the spray drying of step (c) is performed may include a spray nozzle and a drying chamber, and the slurry is atomized into droplets of a predetermined size through the spray nozzle so that a relatively high temperature gas flow exists. is sprayed into the drying chamber.

The raw material (the waste-positive electrode active material and the sub raw material) in the droplets sprayed into the drying chamber is synthesized as a dried precursor having a spherical shape under a temperature environment in the drying chamber.

For the precursor of the raw material in the droplets, the temperature in the drying chamber is preferably controlled within the range of 50 to 500 °C.

The viscosity of the slurry spray-dried in step (c) is 3,000 to 20,000 cp, and the flow rate of compressed air used to spray-dry the relatively high-viscosity slurry through the spray nozzle is preferably 40 L/min or more. . When the flow rate of the compressed air is less than 40 L/min, the spray nozzle is clogged by the slurry having a relatively high viscosity, there is a fear that the spray drying process efficiency is reduced.

In addition, since the slurry has the above-mentioned viscosity range, it is possible to shorten the condensation time during spray drying, and as the content of moisture lost by drying is small, it is possible to obtain a high-density precursor.

If the viscosity of the slurry in step (c) is less than 3,000 cp, not only the condensation time during spray drying increases, but also the density of the precursor decreases as the moisture content lost by drying increases, and the pores in the precursor There is a possibility that a large amount may be formed. A precursor having a low density and a large amount of pores is likely to exhibit weak particle strength. In this case, as the cathode active material collapses during charging/discharging or storage of a lithium secondary battery using the cathode active material prepared using the precursor, the electrochemical properties of the lithium secondary battery may be lowered or the stability may be lowered.

On the other hand, when the viscosity of the slurry exceeds 20,000 cp, sufficient process efficiency cannot be achieved because the fluidity of the slurry in the spray dryer is low, and a precursor having a spherical shape prepared through spray drying is obtained. It can be difficult.

In addition, specific conditions of the spray drying performed in step (c) may refer to Preparation Examples to be described later.

Likewise, the spray drying of step (c) may be repeatedly performed so that the precursor may have a predetermined particle size and shape.

Subsequently, the step (d) of obtaining a lithium composite oxide by heat-treating the precursor is performed.

To this end, before heat-treating the precursor in step (d), a mixture may be prepared by mixing the precursor and the lithium-containing raw material, and then heat treatment may be performed on the mixture.

The lithium-containing raw material input in step (d) includes a lithium compound capable of forming a lithium composite oxide by reacting with the nickel raw material powder. As the lithium compound, lithium hydroxide, lithium carbonate, lithium nitrate or lithium acetate may be used.

The content of the lithium compound added in step (d) is such that the ratio (Li/Metal) of the number of atoms (Li) of lithium to the total number of atoms (Metal) of metal elements other than lithium in the nickel raw material powder (Li/Metal) is 1.5 or less It is preferable to mix so as to be in the range of

If the lithium-containing raw material is additionally added when preparing the mixture in step (e), which will be described later, the content of the lithium compound added in step (d) is the amount of a metal element other than lithium in the nickel raw material powder. The mixture is mixed so that the ratio (Li/Metal) of the number of atoms (Li) of lithium to the total number of atoms (Metal) is in the range of 1.0 or less, and the content of the lithium compound input in step (e) is the nickel raw material powder The mixture is preferably mixed so that the ratio (Li/Metal) of the number of atoms (Li) of lithium to the total number of atoms (Metal) of metal elements other than lithium is in the range of 1.5 or less.

In addition, before the heat treatment of the precursor in step (d), the precursor, the lithium-containing raw material and Mn, Co, B, Ba, Ce, Hf, Ta, Cr, F, Mg, Al, Cr, V, Ti , Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, Sr, Ge, Nd, Gd and Cu by mixing at least one sub-raw material comprising a dopant selected from After preparation, heat treatment may be performed on the mixture.

In this case, the sub raw material may be provided in at least one form selected from sulfate, carbonate, nitrate, acetate, chloride, hydrate, and oxide. In addition, preferably, the sub raw material is also provided in the form of a powder, and may exist in a state that is not substantially dissolved in the solvent. Accordingly, the present application does not require a large amount of process water for dissolving the transition metal-containing raw material powder as well as the nickel raw material powder, unlike the conventional co-precipitation method.

When the mixture of the precursor, the lithium-containing raw material and the sub raw material is heat treated in step (d), an element included in the sub raw material among the lithium composite oxide is doped or at least a portion of the surface of the lithium composite oxide may be coated with an oxide represented by Chemical Formula 3, which will be described later.

까지 분당 2 내지 5

로 승온하여 5 내지 12시간 동안 수행될 수 있다. 상기 단계 (d)의 열처리 온도가 300℃ 미만인 경우, 상기 전구체의 소성이 불충분하게 진행됨에 따라 상기 리튬 복합 산화물의 결정 성장이 불충분할 수 있다. 반면에, 상기 단계 (d)의 열처리 온도가 1,000℃를 초과할 경우, 오히려 상기 리튬 복합 산화물의 열분해가 일어날 수 있다.The heat treatment temperature of step (d) may be 300 to 1,000 ℃. More specifically, the heat treatment of step (d) is 300 to 1,000 while maintaining the O ₂ atmosphere in the kiln

2 to 5 per minute

It can be carried out for 5 to 12 hours by raising the temperature. When the heat treatment temperature of step (d) is less than 300° C., as the sintering of the precursor is insufficiently progressed, crystal growth of the lithium composite oxide may be insufficient. On the other hand, when the heat treatment temperature of step (d) exceeds 1,000° C., thermal decomposition of the lithium composite oxide may occur.

The lithium composite oxide obtained in step (d) may be represented by Formula 1 or Formula 2 below.

[Formula 1]

Li _x Ni _1-y M _y O _2-z X _z

(here,

M is Mn, Co, B, Ba, Ce, Hf, Ta, Cr, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, Sr, At least one selected from Ge, Nd, Gd and Cu,

X is selected from F, S and P,

0.5≤x≤1.5, 0≤y≤0.50, 0≤z≤2)

Here, the element represented by M may be supplied in the form of a sub raw material in at least one step selected from steps (a) to (d).

[Formula 2]

Li _a Ni _1-(b+c+d) Co _b M1 _c M2 _d O _e

(here,

M1 is at least one selected from Mn and Al,

M2 is Mn, B, Ba, Ce, Hf, Ta, Cr, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, Sr, Ge, At least one selected from Nd, Gd and Cu;

M1 and M2 are different from each other,

0.50≤a≤1.50, 0≤b≤0.20, 0≤c≤0.10, 0≤d≤0.05, 1.0≤e≤2.0)

Here, the elements represented by M1 and M2 may each independently be supplied in the form of a sub raw material in at least one step selected from steps (a) to (d).

The average particle diameter of the lithium composite oxide obtained in step (d) is 0.1 μm to 20 μm.

On the other hand, when the positive electrode active material is prepared using a powder-type precursor prepared by pulverizing a nickel-containing raw material powder instead of using a precursor synthesized through the co-precipitation method, the density of the lithium composite oxide contained in the positive electrode active material is increased. There is a possibility that the particle strength may be lowered or exhibited weak particle strength due to the formation of a large amount of pores in the lithium composite oxide. In this case, as the positive electrode active material collapses during charging/discharging or storage of the lithium secondary battery using the positive electrode active material, the electrochemical properties of the lithium secondary battery may be lowered or the stability may be lowered.

However, in the case of the positive active material manufactured by the manufacturing method defined herein, the particle strength of the lithium composite oxide may be improved by improving the density of the precursor and reducing the formation of pores at the same time. The particle strength of the lithium composite oxide may be confirmed by measuring a particle size distribution changed through artificial physical treatment of the positive active material including the lithium composite oxide.

For example, it can be expected that the particle strength of the lithium composite oxide included in the positive electrode active material is stronger as the amount of change in the particle size distribution measured before and after the ultrasonic treatment of the positive active material is small.

Additionally, the lithium composite oxide obtained in step (d) and Mn, Co, B, Ba, Ce, Hf, Ta, Cr, F, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si , Y, Nb, Ga, Sn, Mo, W, P, Sr, Ge, Nd, Gd, and at least one coating raw material containing a coating element selected from Cu to prepare a mixture by mixing the mixture and then heat-treating the mixture Step (e) may be further performed.

In this case, the lithium-containing raw material may be additionally added when preparing the mixture in step (e).

The lithium-containing raw material additionally added in step (e) is a lithium compound capable of inducing additional lithiation of the lithium composite oxide during the heat treatment of step (e). As the lithium compound, lithium hydroxide, lithium carbonate, lithium nitrate or lithium acetate may be used.

The lithium compound additionally added in step (e) is a ratio of the number of atoms (Li) of lithium to the total number of atoms (Metal) of metal elements other than lithium in the lithium composite oxide as a final product (Li/Metal) It is preferable to mix so that it is in the range of 1.5 or less.

An oxide represented by the following Chemical Formula 3 may be generated on at least a part of the surface of the lithium composite oxide through the heat treatment of step (e).

[Formula 3]

Li _α A _β O _γ

(here,

A is Ni, Mn, Co, Fe, Cu, Nb, Mo, Ti, Al, Cr, Zr, Zn, Na, K, Ca, Mg, Pt, Au, B, P, Eu, Sm, Ce, V, At least one selected from Ba, Ta, Sn, Hf, Ce, Gd and Nd,

0≤α≤10, 0<β≤8, 2≤γ≤13)

The oxide represented by Chemical Formula 3 may exist on at least a portion of the surface of the lithium composite oxide, and a region on the surface of the lithium composite oxide in which the oxide represented by the following Chemical Formula 3 exists may be defined as a coating layer.

In addition, when the lithium composite oxide includes primary particles and secondary particles formed by agglomeration of the primary particles, the oxide represented by Formula 3 is the primary particles (eg, between the primary particles). interface) and/or the primary particles may be present on at least a portion of the surface of the secondary particles formed by agglomeration.

The coating layer may exist as a layer for continuously or discontinuously coating the surface of the primary particles and/or the secondary particles formed by agglomeration of the primary particles. When the coating layer is discontinuous, it may exist in the form of an island.

Also, in some cases, the oxide may exist not only in at least a portion of an interface between the primary particles and a surface of the secondary particles, but also in internal pores formed inside the secondary particles.

At this time, the coating layer may exist in the form of a solid solution that does not form a boundary with the primary particles and/or the secondary particles formed by agglomeration of the primary particles, but this is not necessarily the case.

The coating layer may contribute to improving the stability of the lithium composite oxide by removing residual lithium by-products existing on the surface of the lithium composite oxide or improving the electrochemical properties of the lithium composite oxide.

The heat treatment temperature of step (e) for forming the coating layer on the surface of the lithium composite oxide may be 300 to 1,000 °C. More specifically, the heat treatment of step (e) may be performed for 5 to 12 hours by raising the temperature at 2 to 5 °C per minute to 300 to 1,000 °C while maintaining the O ₂ atmosphere in the kiln. When the heat treatment temperature of step (e) is less than 300° C., crystal growth of the oxide constituting the coating layer on the surface of the lithium composite oxide may be insufficient. On the other hand, when the heat treatment temperature of step (e) exceeds 1,000° C., thermal decomposition of the lithium composite oxide and/or the oxide may occur.

Additionally, before performing step (e), disintegration, classification, iron removal, and/or washing with water may be performed on the lithium composite oxide obtained in step (d). there is.

In particular, before performing step (e), a water washing process for the lithium composite oxide obtained in step (d) may be selectively performed.

By reacting the lithium composite oxide obtained in step (d) with a washing solution to remove impurities (eg, including residual lithium by-products and/or unreacted sub raw materials) remaining in the lithium composite oxide, In step (e), an intended reaction between the lithium composite oxide and a sub raw material for forming a coating layer on the surface of the lithium composite oxide may be induced.

cathode active material

According to another aspect of the present invention, there is provided a positive electrode active material manufactured according to the above-described manufacturing method.

The positive active material is provided as a lithium composite oxide including primary particles capable of intercalation/deintercalation of lithium and secondary particles in which the primary particles are aggregated. The lithium composite oxide may be a second lithium composite oxide (hereinafter, referred to as a lithium composite oxide for convenience) prepared according to the above-described manufacturing method.

Here, the primary particle of the lithium composite oxide means one grain or crystallite, and the secondary particle means an aggregate formed by aggregation of a plurality of primary particles. The primary particles may have a rod shape, an oval shape, and/or an irregular shape. A void and/or a grain boundary may exist between the primary particles constituting the secondary particles. Also, in another embodiment, the lithium composite oxide may exist in a single crystal form having an average particle diameter of 0.3 μm or more.

For example, the primary particles may be spaced apart from adjacent primary particles in the interior of the secondary particles to form internal voids. In addition, the primary particles may form a surface existing inside the secondary particles by contacting the internal voids without forming a grain boundary by contacting adjacent primary particles. On the other hand, the surface on which the primary particles present on the outermost surface of the secondary particles are exposed to external air forms the surface of the secondary particles.

Here, the average long axis length of the primary particles is in the range of 0.1 μm to 5 μm, preferably 0.1 μm to 2 μm, so that the optimal density of the positive electrode manufactured using the positive electrode active material according to various embodiments of the present invention can be implemented. . In addition, the average particle diameter of the secondary particles may vary depending on the number of aggregated primary particles, but may be 1 μm to 30 μm.

The primary particle is a lithium composite oxide represented by Formula 1 or Formula 2 below.

[Formula 1]

Li _x Ni _1-y M _y O _2-z X _z

(here,

M is Mn, Co, B, Ba, Ce, Hf, Ta, Cr, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, Sr, At least one selected from Ge, Nd, Gd and Cu,

X is selected from F, S and P,

0.5≤x≤1.5, 0≤y≤0.50, 0≤z≤2)

[Formula 2]

Li _a Ni _1-(b+c+d) Co _b M1 _c M2 _d O _2-e X _e

(here,

M1 is at least one selected from Mn and Al,

M2 is Mn, B, Ba, Ce, Hf, Ta, Cr, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, Sr, Ge, At least one selected from Nd, Gd and Cu;

M1 and M2 are different from each other,

X is at least one selected from F, S and P,

0.50≤a≤1.50, 0≤b≤0.20, 0≤c≤0.10, 0≤d≤0.05, 0≤e≤2.0)

On the other hand, the positive active material prepared by the manufacturing method defined herein using the precursor in powder form prepared by pulverizing the nickel-containing raw material powder has a density similar to that of the positive active material prepared by using the precursor synthesized through the co-precipitation method. and particle strength.

The improved particle strength of the positive active material according to the present disclosure can be confirmed by measuring the particle size distribution changed through artificial physical treatment of the positive active material including the lithium composite oxide.

For example, it can be expected that the particle strength of the lithium composite oxide included in the positive electrode active material is stronger as the amount of change in the particle size distribution measured before and after the ultrasonic treatment of the positive active material is small.

Specifically, in the cumulative particle size distribution curve obtained as a result of particle size distribution measurement, the volume particle size at 10% accumulation is 10% cumulative volume particle size (D ₁₀ ), and the volume particle size at 50% accumulation is 50% cumulative volume particle size (D ₅₀ ) , the 90% cumulative volume particle size is the 90% cumulative volume particle size (D ₉₀ ), and the D ₁₀ change rate, D ₅₀ change rate, and D ₉₀ change rate can be calculated as in Equations 1 to 3 below.

[Equation 1]

D ₁₀ rate of change (%) = (|D ₁₀ before sonication - D ₁₀ after sonication |/D ₁₀ before sonication )*100

[Equation 2]

D ₅₀ rate of change (%) = (|D ₅₀ before sonication - D ₅₀ after sonication |/D ₅₀ before sonication )*100

[Equation 3]

D ₉₀ change rate (%) = (|D ₉₀ before sonication - D ₉₀ after sonication |/D ₉₀ before sonication)*100

At this time, after sonicating the solution in which the positive active material prepared according to the present application is dispersed at a frequency of 40 kHz for 60 seconds, the rate of change of D ₁₀ calculated according to Equation 1 may be less than 1%, preferably less than 0.80%. .

In addition, the rate of change of D ₅₀ calculated according to Equation 2 after ultrasonication for 60 seconds at a frequency of 40 kHz for the solution in which the positive active material prepared according to the present application is dispersed is less than 1.37%, preferably less than 0.50%, more preferably For example, it may be less than 0.40%.

In addition, the rate of change of D ₉₀ calculated according to Equation 3 after sonicating the solution in which the positive active material prepared according to the present application is dispersed at a frequency of 40 kHz for 60 seconds is less than 1.52%, preferably less than 0.50%, more preferably For example, it may be less than 0.20%.

When the rate of change of D ₁₀ , D ₅₀ , and/or D ₉₀ calculated according to Equations 1 to 3 before and after ultrasonication of the positive active material is greater than a predetermined range, it may be difficult to expect structural stability of the positive active material. .

In addition, the positive active material may include a coating layer covering at least a portion of the surface of the primary particles (eg, the interface between the primary particles) and/or the secondary particles formed by aggregation of the primary particles. there is.

For example, the coating layer may be present to cover at least a portion of the exposed surfaces of the primary particles. In particular, the coating layer may be present to cover at least a portion of the exposed surfaces of the primary particles present in the outermost portion of the secondary particles.

Accordingly, the coating layer may exist as a layer for continuously or discontinuously coating the surface of the primary particles and/or the secondary particles formed by aggregation of the primary particles. When the coating layer is discontinuous, it may exist in the form of an island.

Also, in some cases, the oxide may exist not only in at least a portion of an interface between the primary particles and a surface of the secondary particles, but also in internal pores formed inside the secondary particles.

The coating layer present as described above may contribute to the improvement of electrochemical properties and stability of the positive electrode active material.

At this time, the coating layer may exist in the form of a solid solution that does not form a boundary with the primary particles and/or the secondary particles formed by agglomeration of the primary particles, but this is not necessarily the case.

In addition, at least one oxide represented by the following Chemical Formula 3 may be present in the coating layer. That is, the coating layer may be defined as a region in which an oxide represented by the following Chemical Formula 3 exists.

[Formula 3]

Li _α A _β O _γ

(here,

A is Ni, Mn, Co, Fe, Cu, Nb, Mo, Ti, Al, Cr, Zr, Zn, Na, K, Ca, Mg, Pt, Au, B, P, Eu, Sm, Ce, V, At least one selected from Ba, Ta, Sn, Hf, Ce, Gd and Nd,

0≤α≤10, 0<β≤8, 2≤γ≤13)

The oxide represented by Formula 3 is an oxide in which lithium and an element represented by A are complexed, or an oxide of M3, wherein the oxide is, for example, Li _a W _b O _c , Li _a Zr _b O _c , Li _a Ti _b O _c , Li _a Ni _b O _c , Li _a Co _b O _c , Li _a Al _b O _c , Co _b O _c , Al _b O _c , W _b O _c , Zr _b O _c or Ti _b O _c , etc. However, the above-described example is merely described for convenience of understanding, and the oxide defined herein is not limited to the above-described example.

In another embodiment, the oxide represented by Formula 3 may further include an oxide in which lithium and at least two elements represented by A are complexed, or an oxide in which lithium and at least two elements represented by A are complexed. can The oxide in which lithium and at least two elements represented by A are complexed is, for example, Li _a (W/Ti) _b O _c , Li _a (W/Zr) _b O _c , Li _a (W/Ti/Zr ) _b O _c , Li _a (W/Ti/B) _b O _c , etc., but is not necessarily limited thereto.

As described above, in the lithium composite oxide according to this embodiment, at least a portion of the surface of the primary particles (eg, the interface between the primary particles) and/or the secondary particles formed by aggregation of the primary particles By including a coating layer to cover the structural stability can be increased. In addition, life and capacity characteristics can be improved by using such a lithium composite oxide as a cathode active material for a lithium secondary battery.

In addition, the coating layer reduces the residual lithium in the lithium composite oxide and at the same time acts as a diffusion path of lithium ions, thereby having an effect on improving the efficiency characteristics of the lithium secondary battery.

Additionally, the oxide may exhibit a decreasing concentration gradient from the surface portion of the secondary particle toward the center of the secondary particle. Accordingly, the concentration of the oxide may decrease from the outermost surface of the secondary particle toward the center of the secondary particle.

As described above, the oxide exhibits a concentration gradient that decreases from the surface portion of the secondary particle toward the center of the secondary particle, thereby effectively reducing the residual lithium present on the surface of the positive electrode active material to the unreacted residual lithium. side reactions can be prevented in advance. In addition, it is possible to prevent a decrease in crystallinity in the inner surface region of the positive electrode active material due to the oxide. In addition, it is possible to prevent the overall structure of the cathode active material from being collapsed by the oxide during the electrochemical reaction.

lithium secondary battery

According to another aspect of the present invention, a positive electrode including a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector may be provided. Here, the positive electrode active material layer may include a positive electrode active material manufactured according to the manufacturing method according to various embodiments of the present invention as described above as a positive electrode active material.

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, titanium on the surface of aluminum or stainless steel. , 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 be prepared by applying a positive electrode slurry composition including a conductive material and optionally a binder along with the positive electrode active material to the positive electrode current collector.

In this case, the positive active material may be included in an amount of 80 to 99 wt%, more specifically 85 to 98.5 wt%, based on the total weight of the positive active material layer. It may exhibit excellent capacity characteristics when included in the above content range, but is not necessarily limited thereto.

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 has electronic conductivity without causing chemical change. 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 wt% 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 the adhesion between the positive active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (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 wt% based on the total weight of the positive 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, the positive electrode slurry composition prepared by dissolving or dispersing the binder and the conductive material in a solvent may be coated on the positive electrode current collector, and then dried and rolled.

The solvent may be a solvent generally used in the art, dimethyl sulfoxide (DMSO), isopropyl alcohol (isopropyl alcohol), N-methylpyrrolidone (NMP), acetone (acetone) or water, and the like, and any one of them or a mixture of two or more thereof may be used. The amount of the solvent used is enough to dissolve or disperse the positive electrode active material, the conductive material and the binder in consideration of the application thickness of the slurry and the production yield, and to have a viscosity capable of exhibiting excellent thickness uniformity when applied for the production of the positive electrode thereafter. Do.

Further, in another embodiment, the positive electrode may be prepared by casting the positive electrode slurry composition on a separate support and then laminating a film obtained by peeling it from the support on the positive electrode current collector.

In addition, according to another aspect of the present invention, an electrochemical device including the above-described positive electrode may be provided. The electrochemical device may specifically be a battery, a capacitor, or the like, and more specifically, may be a lithium secondary battery.

Specifically, the lithium secondary battery may include a positive electrode, a negative electrode positioned opposite to the positive electrode, and a separator and an electrolyte interposed between the positive electrode and the negative electrode. In addition, the lithium secondary battery may be provided as an anode-free secondary battery. Here, since the 　 anode is the same as described above, a detailed description will be omitted for convenience, and only the remaining components not described above will be described in detail below. In addition, it should be understood that the description related to the negative electrode, which will be described later, is described on the assumption that the negative electrode is present in the lithium secondary battery.

The lithium secondary battery may optionally further include a battery container accommodating the electrode assembly of the positive electrode, the negative electrode, and the separator, and a sealing member sealing the battery container.

The negative electrode may include a negative electrode current collector and an anode 　 active material layer positioned on the negative electrode current collector.

The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel surface. Carbon, nickel, titanium, silver, etc. surface-treated, aluminum-cadmium alloy, etc. may be used. In addition, the negative electrode current collector may have a thickness of typically 3 μm to 500 μm, and similarly to the positive electrode current collector, fine irregularities may be formed on the surface of the current collector to enhance the bonding force of the negative electrode active material. 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 nonwoven body.

The negative electrode active material layer may be prepared by applying a negative electrode slurry composition including a conductive material and optionally a binder along with the negative electrode active material to the negative electrode current collector.

As the anode active material, a compound capable of reversible intercalation/deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metal compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; metal oxides capable of doping and dedoping lithium, such as SiO _β (0 < β < 2), SnO ₂ , vanadium oxide, and lithium vanadium oxide; Alternatively, a composite including the metallic compound and a carbonaceous material such as a Si-C composite or a Sn-C composite may be used, and any one or a mixture of two or more thereof may be used. In addition, a metal lithium thin film may be used as the negative electrode active material. In addition, as the carbon material, both low crystalline carbon and high crystalline carbon may be used. As low crystalline carbon, soft carbon and hard carbon are representative, and as high crystalline carbon, amorphous, plate-like, flaky, spherical or fibrous natural or artificial graphite, Kish graphite (Kish) graphite), pyrolytic carbon, mesophase pitch based carbon fiber, meso-carbon microbeads, liquid crystal pitches (Mesophase pitches), and petroleum and coal tar pitch (petroleum or coal tar pitch) High-temperature calcined carbon such as derived cokes) is a representative example.

The negative active material may be included in an amount of 80 to 99 wt% based on the total weight of the negative electrode and the active material layer.

The binder is a component that assists in bonding between the conductive material, the active material, and the current collector, and may be typically added in an amount of 0.1 to 10 wt% based on the total weight of the negative electrode and the active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoro and roethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

The conductive material is a component for further improving the conductivity of the negative active material, and may be added in an amount of 10 wt% or less, preferably 5 wt% or less, based on the total weight of the negative electrode active material layer. Such a conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery. For example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

In one embodiment, the negative electrode 　 active material layer is prepared by applying and drying a negative electrode 　 slurry composition prepared by dissolving or dispersing the negative electrode 　 active material, and optionally a binder and a conductive material in a solvent on the negative electrode current collector and drying, or the negative electrode 　 slurry It can be prepared by casting the composition on a separate support and then laminating a film obtained by peeling it from the support onto a negative electrode current collector.

In addition, in another embodiment, the negative electrode 　 active material layer is coated with a negative electrode 　 slurry composition prepared by dissolving or dispersing the negative electrode 　 active material, and optionally a binder and a conductive material in a solvent on the negative electrode current collector and drying, or the negative electrode 　 slurry It can also be prepared by casting the composition on a separate support and then laminating the film obtained by peeling it off from the support on the negative electrode current collector.

On the other hand, in the lithium secondary battery, the separator separates the anode and the anode and provides a passage for lithium ions to move, and as long as it is used as a separator in a lithium secondary battery, it can be used without any particular limitation, especially for the movement of ions in the electrolyte It is preferable to have a low resistance to respect and an excellent electrolyte moisture content. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer and ethylene/methacrylate copolymer, or these A laminate structure of two or more layers of may be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high melting point glass fiber, polyethylene terephthalate fiber, etc. may be used. In addition, a coated separator including a ceramic component or a polymer material may be used to secure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

In addition, examples of the electrolyte used in the present invention include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries, and are limited to these. it's not going to be

Specifically, the electrolyte may include an organic solvent and a lithium salt.

The organic solvent may be used without any particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, as the organic solvent, ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon-based solvents such as benzene and fluorobenzene; dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), propylene carbonate, carbonate-based solvents such as PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may contain a double bond aromatic ring or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; Or sulfolane may be used. Among them, a carbonate-based solvent is preferable, and a cyclic carbonate (eg, ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant capable of increasing the charge/discharge performance of the battery, and a low-viscosity linear carbonate-based compound ( For example, a mixture of ethyl methyl carbonate, dimethyl carbonate or diethyl carbonate) is more preferable. In this case, when the cyclic carbonate and the chain carbonate are mixed in a volume ratio of about 1:1 to about 1:9, the performance of the electrolyte may be excellent.

The lithium salt may be used without particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt is LiPF ₆ , LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAl0 ₄ , LiAlCl ₄ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN(C ₂ F ₅ SO ₃ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN(CF ₃ SO ₂ ) _2. LiCl, LiI, or LiB(C ₂ O ₄ ) ₂ , etc. may be used. The concentration of the lithium salt is preferably used within the range of 0.1 to 2.0 M. When the concentration of the lithium salt is included in the above range, since the electrolyte has appropriate conductivity and viscosity, excellent electrolyte performance may be exhibited, and lithium ions may move effectively.

In the electrolyte, in addition to the electrolyte components, for the purpose of improving battery life characteristics, suppressing battery capacity reduction, and improving battery discharge capacity, for example, haloalkylene carbonate-based compounds such as difluoroethylene carbonate, pyridine, tri Ethyl phosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imida One or more additives such as jolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol or aluminum trichloride may be further included. In this case, the additive may be included in an amount of 0.1 to 5 wt% based on the total weight of the electrolyte.

As described above, since the lithium secondary battery containing the positive electrode active material according to the present invention stably exhibits excellent discharge capacity, output characteristics and lifespan characteristics, portable devices such as mobile phones, notebook computers, digital cameras, and hybrid electric vehicles ( It is useful in the field of electric vehicles such as hybrid electric vehicle and HEV).

The external shape of the lithium secondary battery according to the present invention is not particularly limited, but may be a cylindrical shape using a can, a prismatic shape, a pouch type, or a coin type. In addition, the lithium secondary battery may be used not only in a battery cell used as a power source for a small device, but may also be preferably used as a unit cell in a medium or large battery module including a plurality of battery cells.

According to another aspect of the present invention, a battery module including the lithium secondary battery as a unit cell and/or a battery pack including the same may be provided.

The battery module or the battery pack is a power tool (Power Tool); electric vehicles, including electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); Alternatively, it may be used as a power source for any one or more medium-to-large devices in a system for power storage.

Preparation Example 1. Preparation of positive electrode active material

Example 1

As a nickel raw material powder, 1,000 g of nickel oxide (NiO) powder with a purity of 97% and an average particle diameter of 14 μm obtained by pyrrometallurgical from nickel sulfide ore was mixed with 4,500 g of distilled water and stirred to obtain nickel oxide powder. A dispersed slurry was prepared.

Then, the slurry was put into a bead mill (using ZrO ₂ beads, Netch, LabStar Mini) using a bead size of 1.0 mm, and then first wet-milled for 30 minutes and then a bead mill using a bead size of 0.3 mm (ZrO ₂ beads used, Netch, LabStar Mini) was added and then subjected to secondary wet grinding for 30 minutes.

After the secondary wet grinding, the average particle diameter of the nickel raw material powder in the slurry was measured to be 0.2 μm.

The secondary wet-pulverized slurry was put into a raw material storage container attached to a spray dryer (Dongjin Machinery Co., Ltd. DJE003R) and stirred at 200 rpm to keep the slurry from precipitating and separating. The stirring speed of the slurry was adjusted to decrease as the amount of the slurry in the raw material storage container decreased.

The slurry was transferred to the spray drying chamber by a tubular feeding pump at a transfer rate of 1 kg/hr. The atomizer used for spray drying was a two-fluid spray nozzle, and the input temperature (in-let) was maintained at 220 °C and the discharge temperature (out-let) at 100 °C or higher.

In the drying chamber, the temperature was kept constant at 220° C. for rapid moisture removal, and the slurry sprayed by the spray nozzle was atomized in the form of droplets to form a spherical powder (precursor). As a result of spray drying, the precursor had a shape of secondary particles in which a plurality of primary particles were aggregated, and an average particle diameter was measured to be 7.0 μm. The spray-drying result is shown in Fig. 1 (a).

Then, the precursor was put in a gravity-free mixer, and then lithium hydroxide and 24 g of Co ₃ O ₄ powder and 5 g of Al(OH) ₃ powder were added and stirred for 1 hour to prepare a mixture. In this case, the amount of the lithium hydroxide is a ratio (Li/Metal) of the total number of atoms (Li) of Li input as lithium hydroxide in the precursor to the total number of atoms (Metal) of metal elements other than Li in the precursor (Li/Metal) is 1.0 made to be

Then, the mixture was heated to 750° C. at 2° C. per minute while maintaining an O ₂ atmosphere in a kiln, and heat-treated for 12 hours to obtain a lithium composite oxide (positive electrode active material).

As a result of ICP-OES analysis of the obtained positive active material, it was confirmed that the composition of the positive active material was Li _1.00 Ni _0.82 Co _0.15 Al _0.04 O ₂ . In addition, the average particle diameter of the positive active material was measured to be 7.5 μm. The heat treatment result is shown in Fig. 1 (b).

Example 2

Lithium hydroxide weighed so that the ratio of the number of atoms expressed as Li/Metal (the number of elements other than Li) to the metal element (Metal) present in the slurry before the first wet grinding is 0.1 was added, except that , a positive electrode active material was prepared in the same manner as in Example 1.

At this time, the amount of lithium hydroxide mixed with the precursor in the weightless mixer is the ratio of the total number of atoms (Li) of Li input as lithium hydroxide in the precursor to the total number of atoms (Metal) of metal elements other than Li in the precursor (Li/Metal) was set to 1.0.

As a result of ICP-OES analysis of the obtained positive active material, it was confirmed that the composition of the positive active material was Li _1.00 Ni _0.82 Co _0.15 Al _0.04 O ₂ . In addition, the average particle diameter of the positive active material was measured to be 7.3 μm.

The spray drying and heat treatment results of Example 2 are sequentially shown in FIGS. 2 (a) and (b).

Example 3

As a nickel raw material powder, 1,000 g of nickel hydroxide (NiOH) powder with a purity of 96% and an average particle size of 20 μm obtained by pyrrometallurgical from nickel sulfide ore was mixed with 4,800 g of distilled water and stirred to obtain nickel hydroxide powder. A dispersed slurry was prepared.

Subsequently, 160 g of Co ₃ O ₄ powder, 36 g of Al(OH) ₃ powder, and 4 g of H ₃ BO ₃ powder were further added to the slurry, and with respect to the metal element (Metal) present in the slurry, Li/Metal (other than Li) of lithium hydroxide was added so that the ratio of the number of atoms represented by the number of raw metals) was 0.1.

The slurry prepared as described above was put into a bead mill (ZrO ₂ beads used, Netch, LabStar Mini) using a bead size of 0.3 mm, and then wet pulverized for 1.5 hours.

After wet grinding, the average particle diameter of the nickel raw material powder in the slurry was measured to be 0.2 μm.

The wet-pulverized slurry was put into a raw material storage container attached to a spray dryer (Dongjin Machinery Co., Ltd. DJE003R) and stirred at 200 rpm to keep the slurry from precipitating and separating. The stirring speed of the slurry was adjusted to decrease as the amount of the slurry in the raw material storage container decreased.

The slurry was transferred to the spray drying chamber by a tubular feeding pump at a transfer rate of 1 kg/hr. The atomizer used for spray drying was a two-fluid spray nozzle, and the input temperature (in-let) was maintained at 220 °C and the discharge temperature (out-let) at 100 °C or higher.

In the drying chamber, the temperature was kept constant at 220° C. for rapid moisture removal, and the slurry sprayed by the spray nozzle was atomized in the form of droplets to form a spherical powder (precursor). As a result of spray drying, the precursor had a shape of secondary particles in which a plurality of primary particles were aggregated, and an average particle diameter was measured to be 15.5 μm. The spray-drying result is shown in Fig. 3 (a).

Then, the precursor was put in a gravity-free mixer, and lithium hydroxide was added thereto, followed by stirring for 1 hour to prepare a mixture. At this time, the amount of the lithium hydroxide is a ratio (Li/Metal) of the total number of atoms (Li) of Li in the precursor and Li input as lithium hydroxide to the total number of atoms (Metal) of metal elements other than Li in the precursor It was set to 1.0.

Then, the mixture was heated to 750° C. at 2° C. per minute while maintaining an O ₂ atmosphere in a kiln, and heat-treated for 12 hours to obtain a lithium composite oxide (positive electrode active material).

As a result of ICP-OES analysis of the obtained positive active material, it was confirmed that the composition of the positive active material was Li _1.0 Ni _0.81 Co _0.15 Al _0.04 B _0.01 O _2.0 . In addition, the average particle diameter of the positive active material was measured to be 15.2 μm. The heat treatment result is shown in Fig. 3 (b).

Comparative Example 1

A cathode active material having the same composition as in Example 1 was prepared using the NiCo(OH) ₂ hydroxide precursor synthesized through the co-precipitation method.

Specifically, the hydroxide precursor was synthesized as follows.

First, in a 1.5 M complex transition metal sulfuric acid solution in which NiSO ₄ ·7H ₂ O and CoSO ₄ ·7H ₂ O are mixed so that the molar ratio of Ni and Co is 85:15 in a 90L-class reactor, 25wt% of NaOH and 30wt% of NH ₄ OH was added. The pH in the reactor was maintained at 11.5, and the reactor temperature at this time was maintained at 60° C., and N ₂ , an inert gas, was introduced into the reactor to prevent oxidation of the prepared precursor.

After completion of the synthesis stirring, washing and dehydration were performed using a filter press (F/P) equipment to obtain a Ni _0.85 Co _0.15 (OH) ₂ hydroxide precursor.

The average particle diameter of the positive active material was measured to be 14.0 μm. SEM images of the precursor and the positive active material of Comparative Example 1 are sequentially shown in FIGS. 4 (a) and (b).

Comparative Example 2

A positive electrode active material was prepared in the same manner as in Example 1, except that the slurry obtained by first wet grinding (using 0.3 mm beads) was spray-dried for 3 hours instead of secondary wet grinding. As a result of spray drying, the average particle diameter of the precursor was measured to be 7.4 μm, and the average particle diameter of the positive electrode active material was measured to be 7.3 μm.

The spray drying and heat treatment results of Comparative Example 2 are sequentially shown in FIGS. 5 (a) and (b).

Comparative Example 3

A positive electrode active material was prepared in the same manner as in Example 2, except that the slurry obtained by first wet grinding (using 0.3 mm beads) was spray-dried for 3 hours instead of secondary wet grinding. As a result of spray drying, the average particle diameter of the precursor was measured to be 8.6 μm, and the average particle diameter of the positive electrode active material was measured to be 8.5 μm.

The spray drying and heat treatment results of Comparative Example 3 are sequentially shown in FIGS. 6 (a) and (b).

Comparative Example 4

A positive electrode active material was prepared in the same manner as in Example 1, except that the slurry was first wet-grinded for 15 minutes and then second wet-grinded for 30 minutes. As a result of spray drying, the average particle diameter of the precursor was measured to be 7.8 μm, and the average particle diameter of the positive active material was measured to be 6.2 μm.

The spray drying and heat treatment results of Comparative Example 4 are sequentially shown in FIGS. 7 (a) and (b).

Comparative Example 5

A positive electrode active material was prepared in the same manner as in Example 1, except that the slurry was first wet-milled for 1 hour and then second wet-milled for 1 hour. As a result of spray drying, the average particle diameter of the precursor was measured to be 7.8 μm, and the average particle diameter of the positive active material was measured to be 6.2 μm.

The spray drying and heat treatment results of Comparative Example 5 are sequentially shown in FIGS. 8 (a) and (b).

Referring to FIG. 8 , it can be confirmed that the shape of the precursor prepared as a result of spray drying is not close to a spherical shape or has a non-uniform particle size.

That is, it can be expected that not only the process time and cost increase as the primary wet and secondary wet times increase, but also the viscosity of the slurry becomes excessively high, making it difficult to obtain a precursor of a desired shape and particle size according to spray drying. there is.

Accordingly, it can be confirmed that the positive active material finally produced through heat treatment also has a non-uniform shape and particle size, and exhibits a partially collapsed particle shape.

Comparative Example 6

As a nickel raw material powder, 700 g of nickel hydroxide (NiOH) powder with a purity of 96% and an average particle diameter of 35 μm obtained by pyrrometallurgical from nickel sulfide ore is mixed with 3,400 g of distilled water and stirred to disperse the nickel hydroxide powder. A slurry was prepared.

Then, 110 g of Co ₃ O ₄ powder, 25 g of Al(OH) ₃ powder, and 3 g of H ₃ BO ₃ powder were additionally added to the slurry, and with respect to the metal element present in the slurry, Li/Metal (metal raw water other than Li) ), weighted nickel hydroxide was added so that the ratio of the number of atoms represented by ) was 0.8.

The slurry prepared as described above was put into a bead mill (ZrO ₂ beads used, Netch, LabStar Mini) using a bead size of 0.3 mm, and then wet pulverized for 1.5 hours.

The wet-milled slurry was spray-dried in the same manner as in Example 3. As a result of spray drying, the precursor had a shape of secondary particles in which a plurality of primary particles were aggregated, and an average particle diameter was measured to be 6.6 μm.

Then, the precursor was put in a gravity-free mixer, lithium hydroxide was added, and stirred for 1 hour to prepare a mixture. In this case, the amount of the lithium hydroxide is a ratio (Li/Metal) of the total number of atoms (Li) of Li in the precursor and Li input as lithium hydroxide to the total number of atoms (Metal) of metal elements other than Li in the precursor It was set to 1.0.

Then, the mixture was heated to 750° C. at 2° C. per minute while maintaining an O ₂ atmosphere in a kiln, and heat-treated for 12 hours to obtain a lithium composite oxide (positive electrode active material).

As a result of ICP-OES analysis of the obtained positive active material, it was confirmed that the composition of the positive active material was Li _1.0 Ni _0.81 Co _0.15 Al _0.04 B _0.01 O _2.0 . In addition, the average particle diameter of the positive active material was measured to be 9.9 μm.

The spray drying and heat treatment results of Comparative Example 6 are sequentially shown in FIGS. 9 (a) and (b).

Preparation Example 2. Preparation of lithium secondary battery

A positive electrode slurry was prepared by dispersing 92 wt% of each of the positive active material prepared according to Preparation Example 1, 4 wt% of artificial graphite, and 4 wt% of a PVDF binder in 30 g of N-methyl-2 pyrrolidone (NMP). The positive electrode slurry was uniformly applied to an aluminum thin film having a thickness of 15 μm and vacuum dried at 135° C. to prepare a positive electrode for a lithium secondary battery.

For the positive electrode, lithium foil as a counter electrode, a porous polyethylene membrane (Celgard 2300, thickness: 25 μm) as a separator, and LiPF in a solvent in which ethylene carbonate and ethylmethyl carbonate were mixed in a volume ratio of 3:7 A coin battery was prepared using an electrolyte in which ₆ was present at a concentration of 1.15M.

Experimental Example 1. Evaluation of particle characteristics of positive electrode active material

0.1 g of each of the positive active materials obtained in Preparation Example 1 was added to 50 ml of an aqueous sodium hexametaphosphate solution, and then dispersed to obtain a dispersion. Then, the dispersion was measured for the average particle size and particle size distribution of the positive electrode active material in the dispersion using a laser diffraction scattering particle size distribution analyzer (Cillas PSA 1060), and a volume-based cumulative particle size distribution curve was obtained.

Then, the dispersion was sonicated at a frequency of 40 kHz for 60 seconds using the ultrasonicator included in the particle size distribution measuring device, and then D ₁₀ change rate, D ₅₀ change rate, and D ₉₀ change rate were measured.

In the obtained cumulative particle size distribution curve, the volume particle size at 10% accumulation is 10% cumulative volume particle size (D ₁₀ ), the volume particle size at 50% accumulation is 50% cumulative volume particle size (D ₅₀ ), and volume at 90% accumulation The particle size was taken as the 90% cumulative volume particle size (D ₉₀ ).

D ₁₀ rate of change, D ₅₀ rate of change, and D ₉₀ rate of change were calculated as follows.

D ₁₀ rate of change (%) = (|D ₁₀ before sonication - D ₁₀ after sonication |/D ₁₀ before sonication )*100

D ₅₀ rate of change (%) = (|D ₅₀ before sonication - D ₅₀ after sonication |/D ₅₀ before sonication )*100

D ₉₀ change rate (%) = (|D ₉₀ before sonication - D ₉₀ after sonication |/D ₉₀ before sonication)*100

The particle size distribution of the positive active material measured according to the above-described method is shown in Tables 1 and 2 below.

division Example 1 Example 2 Example 3 Comparative Example 1 Ultrasonic O Ultrasonic X Ultrasonic O Ultrasonic X Ultrasonic O Ultrasonic X Ultrasonic O Ultrasonic X < 1μm
(%) 3.8 3.8 3.9 3.9 1.8 1.7 0.2 0.2 D _min (μm) 0.5 0.5 0.6 0.6 0.7 0.8 0.5 0.5 D ₁₀ (μm) 3.0 3.0 2.3 2.3 5.1 5.0 8.5 8.5 D ₅₀ μm) 7.0 7.0 7.3 7.3 15.3 15.2 14.1 14.0 D ₉₀ (μm) 11.9 11.9 12.1 12.1 38.1 38.1 19.7 19.7 D _max (μm) 15.0 15.0 15.0 15.0 45.0 45.0 23.0 23.0 D ₁₀
rate of change
(%) 0.33 0.43 0.80 0.24 D ₅₀
rate of change
(%) 0.14 0.14 0.39 0.64 D ₉₀
rate of change
(%) 0.25 0.00 0.16 0.20

division Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Ultrasonic O Ultrasonic X Ultrasonic O Ultrasonic X Ultrasonic O Ultrasonic X Ultrasonic O Ultrasonic X Ultrasonic O Ultrasonic X < 1μm
(%) 3.7 3.2 2.3 2.2 5.2 4.0 3.4 2.8 3.4 2.2 D _min (μm) 0.5 0.4 0.6 0.5 0.5 0.5 0.5 0.6 0.6 0.6 D ₁₀ (μm) 2.9 3.1 3.4 3.4 2.8 3.0 3.1 3.4 2.2 3.7 D ₅₀ μm) 7.4 7.3 8.6 8.5 6.3 6.2 7.8 7.9 6.6 9.9 D ₉₀ (μm) 15.4 14.3 17.2 17.4 11.4 10.9 13.7 13.9 13.5 22.7 D _max (μm) 23.0 23.0 23.0 30.0 15.0 15.0 15.0 15.0 23.0 36.0 D ₁₀
rate of change
(%) 7.47 0.58 8.33 8.33 38.63 D ₅₀
rate of change
(%) 1.37 2.13 1.45 1.77 33.77 D ₉₀
rate of change
(%) 7.48 1.52 4.69 1.44 40.48

In the case of the positive active material according to Examples 1 to 6, the positive electrode active material prepared according to the co-precipitation method (Comparative Example 1) and the amount of change in the particle size distribution at a level similar to that of the bar, sufficient strength and stability as a positive electrode active material can be secured It is expected that there will be

Experimental Example 2. Evaluation of electrochemical properties of lithium secondary batteries

Charge/discharge experiment by applying a discharge rate of 25°C, voltage range 3.0V to 4.3V, 0.1C using an electrochemical analyzer (Toyo, Toscat-3100) for the lithium secondary battery (coin cell) prepared in Preparation Example 2 was carried out to measure the charge and discharge capacity

In addition, the same lithium secondary battery was charged/discharged 100 times at 25℃ (room temperature life) and 45℃ (high temperature life), respectively, under the conditions of 0.1C/0.1C within the driving voltage range of 3.0V to 4.3V. Afterwards, the ratio of the discharge capacity at the 100th cycle to the initial capacity (cycle capacity retention rate) was measured.

The measurement results are shown in Table 3 below.

division charging capacity
(mAh/g) discharge capacity
(mAh/g) Charging/discharging efficiency (%) Room temperature life (%) High Temperature Life (%) Example 1 222.9 202.0 90.6 96.1 94.4 Example 2 218.2 198.9 91.1 94.7 82.4 Example 3 216.5 200.5 92.6 91.3 86.5 Comparative Example 1 216.4 199.5 92.2 96.3 82.2 Comparative Example 2 217.0 199.7 92.0 65.0 50.3 Comparative Example 3 214.1 198.1 92.5 61.0 41.6 Comparative Example 4 214.4 196.3 91.5 87.7 78.5 Comparative Example 5 215.5 194.0 90.0 86.1 82.2 Comparative Example 6 168.0 140.9 83.8 88.8 78.4

Referring to the results of Table 3, in the case of the positive active materials according to Examples 1 to 6, it can be confirmed that the positive active material prepared by the co-precipitation method (Comparative Example 1) can exhibit a similar level of electrochemical properties. there is.

As mentioned above, although embodiments of the present invention have been described, those of ordinary skill in the art may add, change, delete or add components within the scope that does not depart from the spirit of the present invention described in the claims. Various modifications and changes of the present invention will be possible by this, and this will also be included within the scope of the present invention.

Claims (15)

(a) mixing at least one nickel raw material powder containing a transition metal with a solvent to prepare a slurry in which the nickel raw material powder is dispersed in the solvent;
(b) grinding the nickel raw material powder in the slurry;
(c) preparing a precursor by spray-drying the slurry in which the nickel raw material powder is pulverized; and
(d) mixing at least one sub raw material including the precursor, the lithium-containing raw material and the dopant and then heat-treating to obtain a lithium composite oxide;
containing,
A method for manufacturing a positive electrode active material.
According to claim 1,
The nickel raw material powder used in step (a) is nickel metal powder, nickel oxide, nickel sulfide, nickel hydroxide, nickel ingot, nickel pellet, nickel briquette, nickel mat, nickel scrap, ferronickel, nickel pig iron and nickel Containing at least one selected from the concentrate,
A method for manufacturing a positive electrode active material.
According to claim 1,
The purity of nickel in the nickel raw material powder is 50% or more,
A method for manufacturing a positive electrode active material.
According to claim 1,
Further comprising the step of pulverizing the nickel raw material powder to have an average particle diameter of 1 to 200 μm before the step (a),
A method for manufacturing a positive electrode active material.
According to claim 1,
The slurry of step (a) is the nickel raw material powder, the solvent, and Mn, Co, B, Ba, Ce, Hf, Ta, Cr, F, Mg, Al, Cr, V, Ti, Fe, Zr, Zn , Si, Y, Nb, Ga, Sn, Mo, W, P, Sr, Ge, Nd, Gd and prepared by mixing at least one sub raw material containing a dopant selected from Cu,
A method for manufacturing a positive electrode active material.
According to claim 1,
The slurry of step (a) is prepared by mixing the raw material powder, the solvent, and a lithium-containing raw material,
The content of the lithium-containing raw material mixed in step (a) is less than the content of the lithium-containing raw material mixed in the step (d),
A method for manufacturing a positive electrode active material.
According to claim 1,
The step (b) is performed so that the nickel raw material powder in the slurry has an average particle diameter of 0.1 to 40 μm.
A method for manufacturing a positive electrode active material.
According to claim 1,
wherein step (b) is repeatedly performed using different bead sizes,
A method for manufacturing a positive electrode active material.
According to claim 1,
The precursor prepared in step (c) comprises spherical secondary particles formed by granulation or aggregation of a plurality of primary particles,
A method for manufacturing a positive electrode active material.
According to claim 1,
Mn, Co, B, Ba, Ce, Hf, Ta, Cr, F, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, mixing at least one sub raw material including a dopant selected from Nb, Ga, Sn, Mo, W, P, Sr, Ge, Nd, Gd and Cu;
A method for manufacturing a positive electrode active material.
According to claim 1,
The lithium composite oxide obtained in step (d) is represented by the following Chemical Formula 1,
A method for manufacturing a positive electrode active material.
[Formula 1]
Li _x Ni _1-y M _y O _2-z X _z
(here,
M is Mn, Co, B, Ba, Ce, Hf, Ta, Cr, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, Sr, At least one selected from Ge, Nd, Gd and Cu,
X is selected from F, S and P,
0.5≤x≤1.5, 0≤y≤0.50, 0≤z≤2)
According to claim 1,
The lithium composite oxide obtained in step (d) is represented by the following Chemical Formula 2,
A method for manufacturing a positive electrode active material.
[Formula 2]
Li _a Ni _1-(b+c+d) Co _b M1 _c M2 _d O _e
(here,
M1 is at least one selected from Mn and Al,
M2 is Mn, B, Ba, Ce, Hf, Ta, Cr, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, Sr, Ge, At least one selected from Nd, Gd and Cu;
M1 and M2 are different from each other,
0.50≤a≤1.50, 0≤b≤0.20, 0≤c≤0.10, 0≤d≤0.05, 1.0≤e≤2.0)
According to claim 1,
The lithium composite oxide obtained in step (d) and Mn, Co, B, Ba, Ce, Hf, Ta, Cr, F, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y , Nb, Ga, Sn, Mo, W, P, Sr, Ge, Nd, Gd and further comprising the step (e) of heat-treating after mixing at least one coating raw material comprising a coating element selected from Cu ,
A method for manufacturing a positive electrode active material.
A cathode active material prepared by the method according to any one of claims 1 to 13.
15. The method of claim 14,
After sonicating the positive active material at a frequency of 40 kHz for 60 seconds, the change rate of D ₅₀ of the lithium composite oxide in the positive active material is 1.37% or less,
positive electrode active material.

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