KR20150090963A - Positive electrode active material for rechargable lithium battery, method for synthesis the same, and rechargable lithium battery including the same - Google Patents

Abstract

The present invention relates to a positive electrode active material for a porous lithium secondary battery, a method for producing the same, and a lithium secondary battery including the same, wherein the positive electrode active material for a porous lithium secondary battery comprises a core represented by Chemical Formula 1 and a coating layer disposed on a surface of the core, and the coating layer includes aluminum, aluminum oxide, lithium aluminum oxide, or a combination thereof. [Chemical Formula 1] Li_xM_yO_2 In Chemical Formula 1, M is [Ni_aCo_bMn_((1-a-b))]_(1-c-)_dZr_cW_d, 0.9<=x<=1.5, 0.9<=y<=1.1, 0.4<=a<=0.8, 0<b<=0.4, 0<c<=0.01, and 0<=d<=0.005.

Description

TECHNICAL FIELD [0001] The present invention relates to a positive electrode active material for a lithium secondary battery, a method for producing the same, and a lithium secondary battery including the lithium secondary battery. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

A cathode active material for a lithium secondary battery, a production method thereof, and a lithium secondary battery comprising the same.

A battery is a device that converts the chemical energy generated by an electrochemical oxidation-reduction reaction of an internal chemical substance into electrical energy. When the energy inside the battery is exhausted, the primary battery and the rechargeable secondary battery . Among them, the secondary battery can be used by charging and discharging several times by using reversible conversion between chemical energy and electric energy.

Background Art [0002] With the recent development of high-tech electronics industry, it is becoming possible to miniaturize and lighten electronic equipments, and the use of portable electronic equipments is increasing. The need for a battery having a high energy density as a power source for such portable electronic devices has been increased, and research on lithium secondary batteries has been actively conducted.

Such a lithium secondary battery includes a positive electrode including a positive electrode active material capable of intercalating and deintercalating lithium and a negative electrode including a negative active material capable of intercalating and deintercalating lithium And the electrolyte is injected into the battery cell.

Among them, studies have been made to improve the battery characteristics by using an oxide containing various transition metals as a cathode active material. Examples of the oxide containing a transition metal include lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide and the like.

LiCoO ₂ is a superior cathode material with stable charge / discharge characteristics, excellent electron conductivity, high thermal stability and flat discharge voltage characteristics, but cobalt has a low storage capacity, high cost and toxicity to human body Therefore, development of other cathode materials is desired.

LiNiO ₂ is difficult to synthesize materials and has not been commercialized due to a problem of thermal stability, and LiMn ₂ O ₄ is partly commercialized at a low price. However, since LiMn ₂ O ₄ having a spinel structure has a theoretical capacity of about 148 mAh / g and is smaller than other materials and has a three-dimensional tunnel structure, diffusion resistance is large when lithium ions are inserted and removed, It is lower than LiCoO ₂ and LiNiO ₂ , and has poor life characteristics.

As a material capable of overcoming the above problems, much research has been conducted on materials having a layered crystal structure. Of these, lithium nickel cobalt manganese-based oxides can be used as a material having a layered crystal structure most recently exposed. This material exhibits properties such as low cost, high capacity and excellent thermal stability compared to LiCoO ₂ . However, this material has a limitation in satisfying the charging / discharging cycle characteristic, the rate characteristic, the heat stability and the like at the same time.

In order to improve the battery characteristics, attempts have been made to coat the lithium nickel cobalt manganese oxide with another transition metal such as zirconium and other metals to coat the lithium nickel cobalt manganese oxide with another metal.

A cathode active material for a lithium secondary battery having excellent charge / discharge characteristics, high rate characteristics, and long life characteristics, a method for producing the same, and a lithium secondary battery comprising the same.

One embodiment of the present invention includes a metal oxide represented by the following Chemical Formula 1 and a coating layer disposed on the surface of the metal oxide, wherein the coating layer is formed of a porous material including aluminum, aluminum oxide, lithium aluminum oxide, Of the positive electrode active material for a lithium secondary battery.

[Chemical Formula 1]

Li _x M _y O ₂

Wherein M is represented by [Ni _a Co _b Mn _(1-ab) ] _{1-c- d} Zr _c W _d , 0.9? X? 1.5, 0.9? Y? 1.1, 0.4? A? 0.8, 0 <b ? 0.4, 0 < c? 0.01, and 0? D?

The cathode active material for a lithium secondary battery has pores therein, and the average size of the pores may be 10 nm to 1 탆.

The particle size of the cathode active material for the lithium secondary battery may be 2 탆 to 10 탆.

The tap density of the cathode active material for the lithium secondary battery may be 1 to 1.9 g / ml.

The specific surface area of the cathode active material for the lithium secondary battery may be 0.8 to 1.3 m ² / g.

The cathode active material for the lithium secondary battery may be spherical.

In Formula 1, 0.6? A? 0.8 may be satisfied.

The coating layer may be included in an amount of 0.001 to 0.01 mole per mole of the core.

In another embodiment of the present invention, there is provided a process for preparing a precursor of formula (2) by coprecipitation; Adding a precursor of Formula 2 and a lithium source to a solvent and mixing to prepare a precursor solution; Pulverizing the precursor solution; Spray drying the pulverized precursor solution; Heat-treating the spray-dried material to produce a lithium-transition metal composite oxide; Adding the lithium-transition metal composite oxide and the aluminum compound to a solvent, mixing and drying the mixture; And heat treating the dried material. The present invention also provides a method for producing a cathode active material for a lithium secondary battery.

(2)

[Ni _a Co _b Mn _(1-ab) ] _{1-c- d} Zr _c W _{d (} OH) ₂

0.4? A? 0.8, 0? B? 0.4, 0 <c? 0.01, and 0? D?

The average particle size of the precursor of the formula (2) may be 1 탆 to 20 탆.

The step of pulverizing the precursor solution may be such that the particle size of the precursor and the lithium source is not more than 0.3 탆.

In the step of preparing the lithium-transition metal composite oxide by heat-treating the spray-dried material, the heat treatment may be performed at 860 to 890 ° C, and may be performed for 24 to 36 hours.

In the step of adding the lithium-transition metal composite oxide and the aluminum compound to a solvent and mixing and drying the solvent, the solvent may be water.

The aluminum compound may be aluminum sulfate, aluminum nitrate, aluminum acetate, aluminum chloride, or a combination thereof.

The aluminum compound may be added in an amount of 0.001 to 0.01 mole based on 1 mole of the lithium-transition metal composite oxide.

The heat treatment of the dried material may be performed at 550 ° C to 750 ° C, and may be performed for 5 to 10 hours.

According to another embodiment of the present invention, there is provided a lithium secondary battery including the positive electrode, the negative electrode, and the electrolyte containing the positive electrode active material.

Other details of the embodiments of the present invention are included in the following detailed description.

The positive electrode active material according to one embodiment and the lithium secondary battery including the same have excellent high-rate characteristics and life characteristics.

1 is a scanning electron microscope photograph of a cathode active material of Comparative Example 1. Fig.
2 is a scanning electron micrograph of the cathode active material of Comparative Example 2. Fig.
3 is a scanning electron micrograph of the cathode active material of Example 1. Fig.
4 is a scanning electron microphotograph of the cathode active material of Example 1 and its cross section
5 is a scanning electron microscope photograph of the cut surface of the positive electrode plate of Example 1. Fig.
6 is a graph showing the initial charge / discharge efficiency of the batteries manufactured in Examples 1 and 2 and Comparative Example 1. FIG.
FIG. 7 is a graph showing the charge / discharge characteristics of the batteries manufactured in Examples 1 and 2 and Comparative Example 1, evaluated.
8 is a graph showing life characteristics of batteries of Examples 1 and 2 and Comparative Example 1;

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

One embodiment of the present invention includes a metal oxide represented by the following Chemical Formula 1 and a coating layer disposed on the surface of the metal oxide, wherein the coating layer is formed of a porous material including aluminum, aluminum oxide, lithium aluminum oxide, Of the positive electrode active material for a lithium secondary battery.

[Chemical Formula 1]

Li _x M _y O ₂

Wherein M is represented by [Ni _a Co _b Mn _(1-ab) ] _{1-c- d} Zr _c W _d , 0.9? X? 1.5, 0.9? Y? 1.1, 0.4? A? 0.8, 0 <b ? 0.4, 0 < c? 0.01, and 0? D?

The cathode active material may be a lithium nickel cobalt manganese based oxide doped with zirconium (Zr) and / or tungsten (W) in a predetermined amount and coated with aluminum, aluminum oxide, and / or lithium aluminum oxide have.

The cathode active material for lithium secondary batteries is porous and has pores therein. The average size of the pores may be 10 nm to 1 탆, and 100 nm to 1 탆. Accordingly, the positive electrode active material for a lithium secondary battery can exhibit excellent battery characteristics.

The average size of the pores is measured by observing a cross section of the cathode active material with a scanning electron microscope or the like, and may mean the longest length of the pores.

The particle size of the cathode active material for a lithium secondary battery may be 2 탆 to 10 탆, specifically 2 탆 to 9 탆, 2 탆 to 8 탆, 3 탆 to 10 탆, and 4 탆 to 10 탆. In this case, the cathode active material may exhibit excellent battery characteristics.

The particle size of the cathode active material may mean D50, and D50 means a particle size at 50% by volume ratio in a cumulative size-distribution curve.

The D90 of the cathode active material for the lithium secondary battery may be 10 탆 to 18 탆 and 10 탆 to 15 탆. In this case, the cathode active material may exhibit excellent battery characteristics. D90 means the particle size at 90% by volume in the cumulative distribution curve.

The D10 of the cathode active material for the lithium secondary battery may be 1 탆 to 5 탆 and 1 탆 to 4 탆. In this case, the cathode active material may exhibit excellent battery characteristics. D10 means the particle size at 10% in volume fraction in the cumulative distribution curve.

The tap density of the cathode active material for a lithium secondary battery may be 1 to 1.9 g / ml, specifically 1 to 1.8 g / ml, 1 to 1.7 g / ml, and 1 to 1.6 g / ml. The cathode active material satisfies the tap density within the above range, which is advantageous in electrode production and increases the loading amount of the electrode plate, thereby increasing the energy density of the battery and realizing high output characteristics of the battery.

The specific surface area of the cathode active material for a lithium secondary battery may be 0.8 to 1.3 m ² / g, specifically 0.9 to 1.3 m ² / g, 1.0 to 1.3 m ² / g, and 0.8 to 1.2 m ² / g. Accordingly, the cathode active material can improve the lifetime characteristics and the like of the battery.

The specific surface area means a BET (Bnauer-Emmett-Teller) specific surface area.

The cathode active material for the lithium secondary battery may be spherical. The coating layer may be continuously or discontinuously formed on the surface of the spherical metal oxide, and the final shape of the coated cathode active material may be spherical. In this case, the positive electrode active material can realize excellent battery characteristics.

In the above formula (1), x is the molar ratio of Li and t is the molar ratio of M. The molar ratio x of lithium is 0.9? X? 1.5, and specifically 0.9? X? 1.4, 0.9? X? 1.3, 0.9? X? 1.2.

The M may be a transition metal, and may include nickel, cobalt, manganese, zirconium, and tungsten. M is specifically expressed as [Ni _a Co _b Mn _(1-ab) ] _{1-c- d} Zr _c W _d .

Where a is the molar ratio of nickel, b is the molar ratio of cobalt, c is the molar ratio of zirconium, and d is the molar ratio of tungsten.

The molar ratio of nickel is 0.4? A? 0.8. For example, the metal oxide represented by Formula 1 may be a nickel-based oxide, and 0.5? A? 0.8, 0.55 a? 0.8, and 0.6 a? 0.8. When the content of nickel satisfies the above range, high rate charge / discharge characteristics and high output characteristics of the battery can be realized. In particular, the higher the nickel content, the higher the energy density and the better the price.

The molar ratio of cobalt is 0 < b? 0.4, specifically 0 < b? 0.3, 0.1? B? 0.4 and 0.1? B? 0.3.

Within the ranges of a and b above, the ratio of nickel, cobalt and manganese can be suitably controlled.

0 < c < = 0.001, 0.00 < 0.003? C? 0.007. In this case, the cathode active material may exhibit excellent battery characteristics.

The content of tungsten may be 0? D? 0.005, specifically 0? D? 0.004, 0? D? 0.003, 0.0005? D? 0.005, 0.0006? D? 0.004 and 0.0007? D? In this case, the cathode active material may exhibit excellent battery characteristics.

The coating layer may be contained in an amount of 0.001 to 0.01 mole per 1 mole of the metal oxide represented by the general formula (1). When the content of the coating layer satisfies the above range, the charge / discharge characteristics and life characteristics of the battery can be improved.

The cathode active material can improve charge / discharge characteristics, life characteristics, etc. of the battery by using zirconium and / or tungsten.

In another embodiment of the present invention, there is provided a process for preparing a precursor of formula (2) by coprecipitation; Adding a precursor of Formula 2 and a lithium source to a solvent and mixing to prepare a precursor solution; Pulverizing the precursor solution; Spray drying the pulverized precursor solution; Heat-treating the spray-dried material to produce a lithium-transition metal composite oxide; Adding the lithium-transition metal composite oxide and the aluminum compound to a solvent, mixing and drying the mixture; And heat treating the dried material. The present invention also provides a method for producing a cathode active material for a lithium secondary battery.

(2)

[Ni _a Co _b Mn _(1-ab) ] _{1-c- d} Zr _c W _{d (} OH) ₂

0.4? A? 0.8, 0? B? 0.4, 0 <c? 0.01, and 0? D?

The above-described cathode active material can be produced through the above-described production method. The produced cathode active material can improve the high-rate characteristics, the output characteristics, the life characteristics, and the like of the battery.

The precursor of Formula 2 is prepared by co-precipitation, and the average particle size of the precursor of Formula 2 may be 1 to 20 占 퐉.

The lithium source may be, for example, lithium carbonate, lithium hydroxide, lithium nitrate, lithium oxide, or a combination thereof.

The step of pulverizing the precursor solution may be, for example, grinding using a bead mill.

The step of pulverizing the precursor solution may be carried out such that the particle size of the precursor and the lithium source is 0.3 μm or less. In this case, the spray drying step as the next step can be effectively performed.

In the step of preparing the lithium-transition metal composite oxide by heat-treating the spray-dried material, the heat treatment may be performed at 860 to 890 ° C, and may be performed for 24 to 36 hours. In this case, the lithium transition metal complex oxide can be effectively produced, and the cathode active material containing the lithium transition metal complex oxide can exhibit excellent battery characteristics.

In the method of preparing a cathode active material according to one embodiment, a water-based coating method is used as a coating method. In this case, an environmentally friendly aqueous solvent can be used without using an organic solvent. That is, in the step of adding the lithium-transition metal composite oxide and the aluminum compound to a solvent and mixing and drying the solvent, the solvent may be water. In this case, it has the advantage of being environmentally friendly.

The aluminum compound used as the coating raw material may specifically be aluminum sulfate, aluminum nitrate, aluminum acetate, aluminum chloride, or a combination thereof.

The aluminum compound may be added in an amount of 0.001 to 0.01 mole based on 1 mole of the lithium-transition metal composite oxide. In this case, high-rate characteristics, high-output characteristics, life characteristics, etc. of the battery can be improved.

The heat treatment of the dried material may be performed at 550 ° C to 750 ° C, and may be performed for 5 to 10 hours. In this case, the coating layer can be effectively formed, and the cathode active material containing the cathode active material can exhibit excellent battery characteristics.

The coating layer thus formed appears to mainly contain aluminum oxide. Also, lithium present on the surface of the metal oxide of Formula 1 diffuses into the coating layer, and the coating layer is also considered to include lithium aluminum oxide.

The positive electrode active material may include a coating layer made of aluminum, aluminum oxide, and / or lithium aluminum oxide to achieve excellent battery characteristics.

According to another embodiment of the present invention, there is provided a lithium secondary battery including the positive electrode, the negative electrode, and the electrolyte containing the positive electrode active material.

The positive electrode includes a current collector and a positive electrode active material layer formed on the current collector.

Al may be used as the current collector, but the present invention is not limited thereto.

The cathode active material layer includes a cathode active material, a binder, and optionally a conductive material.

The binder may be selected from, for example, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers comprising ethylene oxide, Styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, and the like can be used.

The conductive material is used for imparting conductivity to the electrode. Any conductive material can be used without causing any chemical change in the battery. Examples of the conductive material include metal powders such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, copper, nickel, aluminum and silver, metal fibers and the like, and conductive materials such as polyphenylene derivatives May be used alone or in combination.

The negative electrode includes a current collector and a negative electrode active material layer formed on the current collector.

The current collector may be a copper foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foil, a copper foil, a polymer substrate coated with a conductive metal, or a combination thereof.

The negative electrode active material layer includes a negative electrode active material, a binder composition, and / or a conductive material.

The negative electrode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, a lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

Descriptions of the negative electrode active material, the binder composition and the conductive material will be omitted.

The electrolyte includes a non-aqueous organic solvent and a lithium salt. The non-aqueous organic solvent and the lithium salt can be used as long as they are compatible with each other, so that detailed explanation is omitted.

Hereinafter, examples and comparative examples of the present invention will be described. The following examples are only illustrative of the present invention and are not intended to limit the scope of the present invention.

Example  One

(1) Preparation of cathode active material

Using a coprecipitation method to synthesize a precursor _{(Ni 0 .60 Mn 0 .20 Co} 0 .20) 0.994 Zr 0 .005 W 0 .001 (OH) 2 (5.5㎛). The precursor and Li ₂ CO ₃ are weighed and dispersed in distilled water. The dispersed slurry is pulverized to a small particle size (Dmax = 0.3 μm or less) using a zirconium bead mill. The pulverized slurry is spray dried with a spray dryer.

1.5 to 5 kg of the spray dried material was charged into a saggar of mullite and then sintered in an air atmosphere in a sintering furnace at a sintering temperature of 870 to 890 ° C and a sintering temperature of 2.85 ° C / do. Sintered for a total of 30 hours at a temperature of 7 hours, a holding time of 10 hours, a cooling time of 2.5 hours, a holding time of 5 hours and a cooling time of 6 hours.

The sintered material was pulverized and classified to obtain lithium nickel cobalt manganese composite metal oxide Li _1.05 (Ni _0.60 Mn _0.20 Co _0.20 ) _0.994 Zr _0.005 W _0.001 O ₂ .

The metal oxide was dispersed in an aqueous solution of 0.005 mol of aluminum nitrate (Al (NO ₃ ) ₃ ) at room temperature and coated for 10 minutes. Thereafter, the mixture was subjected to solid / liquid separation using a filter press, and residual moisture on the surface of the active material was removed using a high-pressure fresh air.

The active / liquid separated active material was dried using a fluid bed dryer at 150 ° C.

3 kg of the dried active material was filled in a saggar of mullite and then fired in a heat treatment furnace at a heat treatment temperature of 550 to 750 ° C at a heating rate of 2.85 ° C / min. Heat for 3 hours, 5 hours and 2 hours for 10 hours.

The aluminum surface-treated active material was pulverized and classified to obtain Li _1.00 (Ni _0.60 Mn _0.20 Co _0.20 ) _0.994 Zr _0.005 W _0.001 Al _0.005 O ₂ .

(2) Lithium secondary battery ( Half - cell )

The mixture was uniformly mixed in a N-methyl-2-pyrrolidone solvent such that the weight ratio of the cathode active material to the conductive material (Denka black) and the binder (PVDF) was 94: 3: 3. The mixture was uniformly applied to an aluminum foil, compressed by a roll press, and vacuum-dried in a vacuum oven at 100 캜 for 12 hours to prepare a positive electrode.

The loading level is 8.5 +/- 0.5 mg / cm ² , the density of the electrode plate is 3 ± 0.1 g / cm ³ , and the thickness of the electrode plate is 40.0 ± 1.0 μm.

A 2032 half-coin cell was prepared according to a conventional method using Li-metal as a counter electrode and 1 mole of LiPF ₆ solution as a liquid electrolyte in a mixed solvent of EC: EMC = 1: 2 as an electrolyte .

Example  2

(OH) ₂ (11.2 탆) was used as a precursor synthesized by coprecipitation method (Ni _{0 .60} Mn _{0 .20} Co _{0 .20} ) and _0.995 Zr _{0 .005} A half cell was manufactured.

Comparative Example  One

A slurry obtained by dispersing raw materials such as Li ₂ CO ₃ , Ni (OH) ₂ , Co (OH) ₂ , Mn ₃ O ₄ , Zr (OH) ₄ and WO ₃ in distilled water without using a precursor synthesized by coprecipitation Was crushed and spray-dried, a cathode active material and a half-cell were prepared in the same manner as in Example 1.

Comparative Example  2

The same procedure as in Example 1 was carried out except that the precursor synthesized by the coprecipitation method was used, but the cathode active material was prepared by mixing the precursor with the lithium source and then heat-treating the aluminum precursor without using the spray drying method To prepare a half-cell.

Evaluation example  1: Evaluation of physical properties of active material

The particle size distribution, tap density and specific surface area of the cathode active materials of Examples 1 and 2 and Comparative Examples 1 and 2 were measured and reported in Table 1 below.

Metrics Comparative Example 1
(Wetting active material) Comparative Example 2
(Coprecipitated active material) Example 1
(Co-op + wet) Example 2
(Co-op + wet) Particle size distribution
(탆) Dmin 0.36 2.61 1.64 1.64 D10 3.46 5.69 3.21 3.58 D50 9.89 11.20 6.51 7.16 D90 19.36 23.18 13.17 13.61 Dmax 31.29 38.95 24.71 21.28 Tap density (g / ml) 2.26 1.78 1.51 1.33 BET specific surface area (m ² / g) 0.46 0.18 1.00 1.05

SEM photographs of the cathode active materials of Comparative Examples 1, 2, and 1 are shown in FIGS. 1, 2, and 3, respectively. Referring to FIG. 3, which is a photograph of Example 1, it can be seen that a spherical and porous active material was produced.

Evaluation example  2: active material and Plate  Section analysis

4 is a scanning electron microscope (SEM) image of the cathode active material of Example 1 and its cross section. Referring to FIG. 4, it can be seen that there are many pores in the cathode active material of Example 1.

5 is a scanning electron microscope photograph of the cut surface of the positive electrode plate of Example 1. Fig. Referring to FIG. 5, even when the electrode plate was milled at a high rolling density (3 ± 0.1 g / cm ³ ), it was found that the cathode active material of Example 1 showed almost no damage such as physical fracture phenomenon.

Evaluation example  3: Charging and discharging  characteristic

The initial charge and discharge efficiencies of the batteries prepared in Examples 1 and 2 and Comparative Example 1 were measured, and the results are shown in FIG. 6 and Table 2 below.

Charging conditions: CC / CV 0.1C 4.4V, 1 / 20C cutoff

Discharge condition: CC, 0.1C 3.0V cutoff

Comparative Example 1 Example 1 Example 2 Charging capacity (mAh / g) 208.6 206.1 206.7 Discharge capacity (mAh / g) 188.3 187.2 189.7 efficiency(%) 90.3 9038 91.8

Referring to FIG. 6 and Table 2, it can be seen that the initial efficiencies of Examples 1 and 2 are superior to those of Comparative Examples.

Evaluation example  4: By rate  characteristic

The characteristics of the batteries prepared in Examples 1 and 2 and Comparative Example 1 were evaluated according to the rate. The results are shown in FIG. 7 and Table 3 below. Charging and discharging conditions were the same as those in Evaluation Example 3 above.

C-rate Comparative Example 1 Example 1 Example 2 0.1 100 100.0 100.0 0.2 97.9 97.7 97.9 0.5 95.1 94.6 94.8 1.0 91.9 92.3 92.2 2.0 88.8 89.6 89.7 5.0 81.9 85.6 85.4

The values shown in Table 3 mean the charge-discharge efficiency (%) by rate.

Referring to Table 3 and FIG. 7, it can be confirmed that the output characteristics at the high rate are better in the embodiment than the comparative example.

Evaluation example  5: Evaluation of battery life characteristics

Life characteristics of the batteries of Examples 1 and 2 and Comparative Example 1 were evaluated. The results are shown in Fig. 8 and Table 4 below. Charging and discharging conditions were the same as those in Evaluation Example 3 above.

The first discharge capacity (mAh / g) 50th discharge capacity (mAh / g) Capacity retention rate (%) Comparative Example 1 171.9 162.0 94.2 Example 1 171.7 165.3 96.3 Example 2 174.1 166.6 95.7

Referring to Table 4 and FIG. 8, it can be seen that the life characteristics of the Examples are better than those of the Comparative Examples.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. As will be understood by those skilled in the art. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (19)

A metal oxide represented by the following formula (1), and
And a coating layer disposed on a surface of the metal oxide,
Wherein the coating layer comprises at least one of aluminum, aluminum oxide, lithium aluminum oxide, or a combination thereof. The positive electrode active material for a porous lithium secondary battery includes:
[Chemical Formula 1]
Li _x M _y O ₂
In the above formula (1), M is [Ni _a Co _b Mn _(1-ab) ] _{1-c- d} Zr _c W _d ,
0.9? X? 1.5, 0.9? Y? 1.1, 0.4? A? 0.8, 0 <b? 0.4, 0 <c? 0.01, and 0? D? The method of claim 1,
Wherein the positive electrode active material for a lithium secondary battery has pores therein and the average size of the pores is 10 nm to 1 占 퐉. The method of claim 1,
Wherein the cathode active material for a lithium secondary battery has a particle diameter of 2 占 퐉 to 10 占 퐉. The method of claim 1,
Wherein the tap density of the cathode active material for a lithium secondary battery is 1 to 1.9 g / ml. The method of claim 1,
Wherein the specific surface area of the positive electrode active material for the lithium secondary battery is 0.8 to 1.3 m ² / g. The method of claim 1,
Wherein the positive electrode active material for a lithium secondary battery is a spherical positive electrode active material for a lithium secondary battery. The method of claim 1,
Wherein in Formula 1, 0.6? A? 0.8, the cathode active material for lithium secondary batteries is 0.6? A? 0.8. The method of claim 1,
Wherein the coating layer is contained in an amount of 0.001 to 0.01 mole per 1 mole of the core. Preparing a precursor of formula (2) by coprecipitation;
Adding a precursor of Formula 2 and a lithium source to a solvent and mixing to prepare a precursor solution;
Pulverizing the precursor solution;
Spray drying the pulverized precursor solution;
Heat-treating the spray-dried material to produce a lithium-transition metal composite oxide;
Adding the lithium-transition metal composite oxide and the aluminum compound to a solvent, mixing and drying the mixture; And
A method for producing a cathode active material for a lithium secondary battery, comprising: heat treating a dried material;
(2)
[Ni _a Co _b Mn _(1-ab) ] _{1-c- d} Zr _c W _{d (} OH) ₂
0.4? A? 0.8, 0? B? 0.4, 0 <c? 0.01, and 0? D? The method of claim 9,
Wherein the average particle size of the precursor of Formula 2 is 1 占 퐉 to 20 占 퐉. The method of claim 9,
Wherein the step of pulverizing the precursor solution comprises pulverizing the precursor and the lithium source to a particle size of 0.3 m or less. The method of claim 9,
Wherein the heat treatment is performed at a temperature of 860 to 890 DEG C in the step of heat-treating the spray-dried material to produce a lithium-transition metal composite oxide. The method of claim 9,
Wherein the heat treatment is performed for 24 to 36 hours in the step of preparing the lithium-transition metal composite oxide by heat-treating the spray-dried material. The method of claim 9,
Wherein the solvent is water, wherein the lithium transition metal composite oxide and the aluminum compound are added to a solvent and mixed and then dried. The method of claim 9,
Wherein the aluminum compound is aluminum sulfate, aluminum nitrate, aluminum acetate, aluminum chloride, or a combination thereof. The method of claim 9,
Wherein the aluminum compound is added in an amount of 0.001 to 0.01 mole per 1 mole part of the lithium-transition metal composite oxide. The method of claim 9,
Wherein the step of heat-treating the dried material is performed at a temperature of 550 ° C to 750 ° C. The method of claim 9,
Wherein the heat treatment of the dried material is performed for 5 to 10 hours. A positive electrode comprising the positive electrode active material of any one of claims 1 to 8,
Cathode, and
A lithium secondary battery comprising an electrolytic solution.

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