WO2013081291A1 - Preparation method of lithium titanium composite oxide doped with dissimilar metal, and lithium titanium composite oxide doped with dissimilar metal prepared thereby - Google Patents

Abstract

The present invention relates to a preparation method of a lithium titanium composite oxide doped with a dissimilar metal, and a lithium titanium composite oxide doped with a dissimilar metal prepared thereby, and more specifically, to a preparation method of a lithium titanium composite oxide doped with a dissimilar metal in which the size of primary particles is finely controlled by doping a dissimilar metal and using a spray drying method, and a lithium titanium composite oxide doped with a dissimilar metal prepared thereby. The preparation method of a lithium titanium composite oxide doped with a dissimilar metal and the lithium titanium composite oxide doped with a dissimilar metal prepared thereby, of the present invention, allow the size of primary particles to be finely controlled compared with conventional lithium titanium composite oxides, and inhibit the formation of rutile titanium oxide, thereby providing a battery with high initial charge/discharge efficiency and rate capability.

Description

Method for producing lithium titanium composite oxide doped with a dissimilar metal, and lithium titanium composite oxide doped with a dissimilar metal produced thereby

The present invention relates to a method for producing a lithium titanium composite oxide doped with a dissimilar metal, and a lithium titanium composite oxide doped with a dissimilar metal prepared by the present invention. The present invention relates to a method for producing a lithium titanium composite oxide doped with a dissimilar metal capable of finely controlling the size of primary particles, and to a lithium titanium composite oxide doped with a dissimilar metal prepared thereby.

BACKGROUND ART Non-aqueous electrolyte batteries in which charge and discharge are performed by lithium ions moving between a negative electrode and a positive electrode are actively researched and developed as high energy density batteries. In recent years, attention has been paid to lithium titanium composite oxides having a high Li occlusion and release potential. Lithium titanium composite oxide has advantages in that rapid charging or low temperature performance is excellent because metal lithium does not precipitate in principle at a lithium occlusion and release potential.

The lithium titanium composite oxide includes spinel type lithium titanate represented by the general formula Li _{(1 + x)} Ti _(2-x) O _y (x = -0.2 to 1.0, y = 3 to 4), and representative examples thereof Li _4/3 Ti _5/3 O ₄ , LiTi ₂ O ₄ and Li ₂ TiO ₃ . This material has been used conventionally as a positive electrode active material, and can also be utilized as a negative electrode active material, and its future is expected as a positive electrode and negative electrode active material of a battery. They have a voltage of 1.5 V on a lithium basis and have a long lifetime. In addition, since the expansion and contraction at the time of charge-discharge can be neglected, it is an electrode material of interest in the enlargement of a battery. In particular, the spinel-type lithium titanate (composition formula Li _{4 + x} Ti ₅ O ₁₂ (0 ≦ _x ≦ 3)) is attracting attention because of its small volume change during charge and discharge, and reversibly excellent.

However, the theoretical capacity of the spinel-type lithium titanate is 175 mAh / g, and there is a limit to high capacity. In addition, the spinel lithium titanate is partially separated into rutile TiO ₂ (r-TiO ₂ ) during the manufacturing process. These rutile TiO ₂ (r-TiO ₂ ) is a rock salt structure, which is electrochemically active, but has a low reaction rate, an inclined potential curve, and a small capacity, thereby reducing the effective capacity of the obtained lithium titanium composite oxide. There was a problem of making it small.

The present invention suppresses the production of rutile titanium dioxide by doping and spray-drying the dissimilar metal in order to solve the problems of the prior art as described above, dissimilar metal with improved initial capacity and rate characteristics by controlling the size of the primary particles An object of the present invention is to provide a method for producing a doped lithium titanium composite oxide and a lithium titanium composite oxide doped with a dissimilar metal produced thereby.

The present invention to achieve the above object

i) solid phase mixing of dissimilar metal-containing compounds, lithium-containing compounds, titanium oxides in a stoichiometric ratio;

ii) dispersing the solid mixture of i) in a solvent and wet grinding until it contains particles having an average particle diameter of 0.3 μm to 0.8 μm to prepare a slurry;

iii) spray drying the slurry of ii): and

and iv) firing the spray dried slurry of iii).

In the method for producing a lithium titanium composite oxide doped with a dissimilar metal of the present invention, the metal is any one or more selected from the group consisting of Na, Zr, K, B, Mg, Al, and Zn, preferably Na or It is characterized by being Zr.

In the method for producing a lithium titanium composite oxide doped with a dissimilar metal of the present invention, the Na-containing compound as the dissimilar metal is sodium carbonate, sodium hydroxide, or a mixture of sodium carbonate and sodium hydroxide, and the Zr-containing compound is Zr (OH) ₄ , ZrO ₂ or a mixture thereof.

In the method for producing a lithium titanium composite oxide doped with a dissimilar metal of the present invention, the titanium oxide is characterized by being anatase or hydrous titanium oxide.

In the method for producing a lithium titanium composite oxide doped with a dissimilar metal of the present invention, the lithium-containing compound is characterized in that lithium hydroxide or lithium carbonate.

In the method for producing a lithium titanium composite oxide doped with a dissimilar metal of the present invention, wet grinding in step ii) is performed using water as a solvent and wet grinding at 2000 to 4000 rpm using zirconia beads. do.

In the method for producing a lithium titanium composite oxide doped with a dissimilar metal of the present invention, in the step iii) of spray drying the slurry of step ii), the input hot air temperature is 250 to 300 ° C and the exhaust hot air temperature is 100 to 150 ° C. It is characterized by spray-drying.

In the method for producing a lithium titanium composite oxide doped with a dissimilar metal of the present invention, the calcination process in step iv) may include spray drying the body in step iii) in a reducing atmosphere at 700 to 800 ° C. for 5 to 10 hours. It is characterized in that during the firing.

The present invention is also prepared by a method for producing a lithium titanium composite oxide doped with a dissimilar metal of the present invention, primary particles aggregate to form secondary particles, and the diameter of the primary particles is 0.3 μm to 0.7 μm. ego, The secondary particles are characterized in that the diameter of 5㎛ 25㎛.

The lithium titanium composite oxide doped with a dissimilar metal of the present invention is characterized in that the dissimilar metal is doped with more than 0 wt% and 5 wt% or less.

Lithium titanium composite oxide doped with a dissimilar metal of the present invention is characterized by a spinel structure.

Lithium titanium composite oxide doped with a dissimilar metal of the present invention is characterized in that the main peak strength of the rutile titanium dioxide is 0.5 or less.

The present invention also provides a positive electrode using the lithium titanium composite oxide doped with a dissimilar metal of the present invention as a positive electrode active material, or a negative electrode using the negative electrode active material.

The present invention also provides a lithium secondary battery containing a positive electrode using the lithium titanium composite oxide doped with the dissimilar metal of the present invention as a positive electrode active material, or a lithium titanium composite oxide doped with the dissimilar metal of the present invention as a negative electrode active material. Provided is a lithium secondary battery containing a negative electrode.

Hereinafter, the present invention will be described in more detail.

In the production method of the present invention, a lithium compound, a titanium compound and a dissimilar metal are mixed at the same time by solid phase mixing and wet grinding, and a lithium titanium composite oxide having finely controlled diameters of primary particles by spray drying after firing is prepared. It is a technical feature.

The titanium oxide containing compound used as a starting material may be any of chloride, sulfate or organic salt. However, it is preferable to use anatase type titanium dioxide or hydrous titanium oxide as a crystal structure of the titanium oxide containing compound used as a starting material in order to manufacture the lithium titanium composite oxide excellent in discharge capacity or a battery characteristic like this invention. .

The anatase titanium dioxide needs to be at least 95% pure, preferably at least 98% pure. If the purity is less than 95%, it is not preferable because the capacity per weight of the active decreases. Although high purity, for example, having a purity of 99.99%, may be used, in this case, the cost is high. When considered from the viewpoint of the electrode active material, when the purity is 98% or more, the influence of the particle diameter and the shape becomes larger than the high purity effect. The hydrous titanium oxide must have a purity of at least 90% before firing in order to obtain anatase-type titanium dioxide having a purity in the above range after firing for the same reason as the above-described anatase type titanium oxide.

In the production method of the present invention, the lithium compound used as the starting material may be a lithium salt such as lithium hydroxide, lithium hydroxide monohydrate, lithium oxide, lithium carbonate or lithium carbonate.

In the production method of the present invention, the doped metal is any one or more selected from the group consisting of Na, Zr, K, B, Mg, Al, and Zn, preferably Na or Zr.

The compound containing Na is preferably sodium hydroxide, sodium carbonate or a mixture thereof. The compound containing Zr is preferably Zr (OH) ₄ , ZrO ₂ or a mixture thereof.

In the present invention, the dissimilar metal in the lithium titanium composite oxide is characterized in that the doped to more than 0% by weight 5% by weight. When the content of the doping metal is 0% by weight, the safety improvement effect of the battery according to the dissimilar metal doping is insignificant, and when the content of the doping metal is more than 5% by weight, the conductivity may be lowered, resulting in deterioration of overall performance of the battery.

The method for producing a lithium titanium composite oxide according to the present invention comprises mixing a lithium compound, a titanium compound, and a doped metal in a stoichiometric ratio as a starting material, dispersing the solid mixture in a liquid medium, and spraying a slurry produced by wet grinding in a known method. And granulated by dry granulation, a granulated powder of secondary particles formed by aggregation of primary particles can be used.

In the production method of the present invention, it is preferable to use a method of wet grinding using a medium stirring grinder or the like after dispersing the co-mixed lithium compound, titanium compound and doped metal in a dispersion medium. Although various organic solvents and aqueous solvents can be used as a dispersion medium used for the wet grinding of a slurry, water is preferable. The total weight ratio of the raw material compound to the weight of the entire slurry is 50% by weight or more, preferably 60% by weight or less. When the weight ratio is less than the above range, since the slurry concentration is extremely thin, the spherical particles produced by spray drying tend to become smaller than necessary or break easily. If this weight ratio exceeds the above range, it is difficult to maintain uniformity of the slurry.

It is preferable that the average particle of the solid in a slurry is wet-pulverized at 2000-4000 rpm so that average particle diameter D50 may be 0.3 micrometer-0.8 micrometer. If the average particle diameter of the solids in the slurry is too large, the reactivity in the firing process may not only decrease, but also the sphericity decreases, and the final powder packing density tends to decrease. However, since atomization more than necessary leads to an increase in the cost of the grinding, wet grinding is usually performed until the average particle diameter of the grinding product is 0.3 µm to 0.8 µm.

Primary particles are bonded to form secondary particles by spray drying of the lithium titanium composite oxide powder of the present invention, wherein the primary particles have a diameter of 0.3 μm to 0.7 μm, and the diameter of the secondary particles is 5 μm to 25 μm. Is generated.

The means for spraying is not particularly important and is not limited to pressurizing a nozzle having a specified pore size, in fact any known spray-drying apparatus may be used. A nebulizer is generally classified into a rotary disk type and a nozzle type, and the nozzle type is divided into a pressure nozzle type and a two-fluid nozzle type. In addition, any means well known in the art may be used, such as a rotary atomizer, a pressure nozzle, a pneumatic nozzle, a sonic nozzle, and the like. Feed rate, feed viscosity, desired particle size of the spray-dried product, dispersion, droplet size of water-in-oil emulsion or water-in-oil microemulsion, and the like are typically factors considered in the selection of the spraying means.

In the step of spray-drying the slurry of ii) in step iii), spray-drying the input hot air temperature to 250 to 300 ° C. and the exhaust hot air temperature to 100 to 150 ° C. is preferable to increase the shape, size and crystallinity of the particles. .

The mixed powder thus obtained is then calcined. As baking temperature, although it changes also with kinds of other metal compounds, such as a lithium compound, a titanium oxide, and a dissimilar metal used as a raw material, it is 600 degreeC or more normally, Preferably it is 700 degreeC or more, and is usually 900 degrees C or less, Preferably Preferably it is 800 degrees C or less. The firing conditions at this time depend on the raw material composition, but when the firing temperature is too high, the primary particles grow excessively. On the contrary, when the firing temperature is too low, the bulk density is small and the specific surface area is excessively large.

Although baking time changes also with temperature, if it is a temperature range mentioned above normally, it is 30 minutes or more, Preferably it is 5 hours or more, and also usually 20 hours or less, Preferably it is 10 hours or less. If the firing time is too short, it is difficult to obtain lithium titanium composite oxide powder having good crystallinity, and it is not very practical that it is too long. If the firing time is too long and then pulverization is required or pulverization becomes difficult after that, it is preferably 10 hours or less.

Although the atmosphere at the time of baking is baked in air atmosphere, it can be set as inert gas atmosphere, such as nitrogen and argon, depending on the composition and structure of the compound to manufacture. It is preferable to use these by pressurizing.

The present invention also provides a lithium titanium composite oxide doped with a dissimilar metal produced by the production method of the present invention.

The composition of each component of the lithium titanium composite oxide doped with the dissimilar metal synthesized in the present invention can be adjusted by the input ratio of each compound at the time of mixing, that is, the mixing ratio. In addition, the particle size distribution, BET specific surface area, tap density, and green compact density which are powder characteristics can be adjusted by a mixing method and an oxidation process.

The lithium titanium composite oxide doped with a dissimilar metal of the present invention is configured in a state of secondary particles formed by aggregating primary particles, the diameter of the primary particles is 0.3 to 0.7 μm, and the diameter of the secondary particles is 5 to 25. It is characterized by being a micrometer.

The lithium titanium composite oxide doped with a dissimilar metal prepared by the manufacturing method of the present invention is characterized by a spinel structure. In particular, the lithium titanium composite oxide doped with a dissimilar metal prepared by the production method of the present invention is characterized in that the main peak strength of the rutile titanium dioxide is 0 to 0.5.

The main peak of rutile titanium dioxide is 2θ = 27.4. The lithium titanium composite oxide doped with a dissimilar metal prepared by the production method of the present invention has a main peak size of rutile titanium dioxide which reduces capacity as impurities, and has a small amount of rutile titanium dioxide. It not only improves the properties but also increases the battery capacity.

The metal-doped lithium titanium composite oxide of the present invention can finely control the size of primary particles than the conventional lithium titanium composite oxide by doping a metal, thereby providing a battery having a high initial charge and discharge efficiency and a rate characteristic of the battery.

The method for producing a lithium titanium composite oxide doped with a dissimilar metal of the present invention and the lithium titanium composite oxide doped with a dissimilar metal prepared therein are lithium titanium composites by mixing, pulverizing and spray-drying dissimilar metals during a lithium titanium composite oxide manufacturing process. While doping different metals on the surface of the oxide, the size of the primary particles can be finely controlled than the conventional lithium titanium composite oxide, thereby providing a battery having a high initial charge and discharge efficiency and a rate characteristic of the battery.

1 is a SEM photograph of the lithium-doped lithium titanium composite oxide prepared in Example 1 of the present invention and the lithium titanium composite oxide of Comparative Example.

Figure 2 shows the results of measuring the diameter of the primary particles in the SEM photograph of the lithium-doped lithium titanium composite oxide prepared in Example 1 of the present invention.

Figure 3 shows an XRD photograph of the Na-doped lithium titanium composite oxide prepared in Example 1 of the present invention and the lithium titanium composite oxide of the comparative example.

Figure 4 shows the result of measuring the initial charge and discharge characteristics at 0.1C of each test cell containing the lithium titanium composite oxide prepared in Example 1 of the present invention and the lithium titanium composite oxide of the comparative example.

5 is a charge and discharge at 0.1C to 5C with a current density of 0.2 mA / cm 2 of the test cell comprising the lithium titanium composite oxide prepared in Example 1 of the present invention and the test cell containing the lithium titanium composite oxide of Comparative Example The result of the experiment is shown.

Figure 6 shows a SEM photograph of the Zr-doped lithium titanium composite oxide prepared in Example 2 of the present invention and the lithium titanium composite oxide of the comparative example.

FIG. 7 shows XRD photographs of a Zr-doped lithium titanium composite oxide prepared in Example 2 and a lithium titanium composite oxide of Comparative Example.

FIG. 8 shows the results of measuring initial charge and discharge characteristics at 0.1C of each test cell including the lithium titanium composite oxide doped with Zr prepared in Example 2 and the lithium titanium composite oxide of Comparative Example.

9 and 10 are the test cell containing the lithium titanium composite oxide prepared in Example 2 of the present invention and the test cell containing a lithium titanium composite oxide of Comparative Example at a current density of 0.2 mA / cm 2 at 0.1C to 5C The results of the charge and discharge experiments are shown.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited by the following examples.

Example 1 Preparation of Na-doped Lithium Titanium Composite Oxide as Dissimilar Metal

As a starting material, 1 mol of lithium hydroxide, 1 mol of anatase type titanium oxide, and 1 mol of sodium carbonate and sodium hydroxide mixtures were mixed in solid phase, and dissolved in water with stirring.

After wet grinding at 3000 rpm using zirconia beads, spray-drying the hot air temperature to 270 ° C. and the exhaust hot air temperature to 120 ° C., and heat-treating for 10 hours under an oxygen atmosphere of 700 ° C. Oxides were prepared.

Example 2 Preparation of Zr Doped Lithium Titanium Composite Oxide as Dissimilar Metal

As a starting material, 1 mol of lithium hydroxide, 1 mol of anatase type titanium oxide, and 1 mol of zirconium hydroxide were mixed in solid phase, and dissolved in water with stirring.

After wet grinding at 3000 rpm using zirconia beads, spray-dried hot air temperature was 270 ° C., exhaust hot air temperature was 120 ° C., and thermally treated at 700 ° C. for 10 hours under an oxygen atmosphere of Zr-doped lithium titanium composite. Oxides were prepared.

Comparative Example

Lithium titanium composite oxide was prepared in the same manner as in Examples 1 and 2, except that only 1 mol of lithium hydroxide and 1 mol of anatase type titanium oxide were used as starting materials, and no sodium carbonate or zirconium hydroxide for dissimilar metal doping was added. Was prepared.

Experimental Example 1 SEM Photographic Measurement

The results of measuring the diameters of the primary particles in SEM images and enlarged SEM images of lithium titanium composite oxides of Comparative Examples and lithium titanium composite oxides doped with Na and Zr, respectively, prepared in Examples 1 and 2, respectively. 1, 2 and 6 are shown.

In FIG. 1 and FIG. 2, in the case of the lithium titanium composite oxide doped with Na as a dissimilar metal according to Example 1 of the present invention, the primary particles are composed of aggregated secondary particles, and the diameter of the primary particles is 0.3. It can be confirmed that it is spherical in the range of µm to 0.7 µm, and the secondary particles have a diameter of 2 µm.

1 and 6, the diameter of the primary particles of the lithium titanium composite oxide doped with the dissimilar metals of Examples 1 and 2 (Na, Zr, respectively) is finely controlled compared to the lithium titanium composite oxide of the comparative example, and accordingly It can be seen that when the secondary particles are formed, the voids are reduced more than in the comparative example.

Experimental Example 2 XRD Measurement

XRD photographs of the lithium titanium composite oxide and Na-Zr doped lithium titanium composite oxide and the comparative example, respectively, prepared in Examples 1 and 2, respectively, are shown in FIGS. 3 and 7.

3 and 7, the lithium titanium composite oxide doped with Na and Zr as the dissimilar metal according to the exemplary embodiment of the present invention may have a spinel structure. In addition, in the case of the lithium titanium composite oxide doped with Na and Zr as the dissimilar metal according to the embodiment of the present invention, it can be seen that the peak of titanium dioxide on the rutile is not observed. This is because Na and Zr added for doping react with rutile titanium dioxide, thereby improving battery performance.

Production Example Production of Coin Battery

As the dissimilar metals prepared in Examples 1 and 2, a lithium titanium composite oxide doped with Na and Zr, respectively, was used as a cathode active material, and a lithium foil was used as a counter electrode, and a porous polyethylene membrane (manufactured by Celgard ELC, Celgard 2300). (Thickness: 25 μm) as a separator, and a liquid electrolyte in which LiPF ₆ is dissolved at a molar concentration of 1 mol in a solvent in which ethylene carbonate and dimethyl carbonate are mixed at a volume ratio of 1: 2 according to a commonly known manufacturing process. The battery was prepared. The coin battery was similarly manufactured in the case of a comparative example.

Experimental Example 3 Evaluation of Initial Charging and Discharging Characteristics

An electrochemical analyzer (TOSCAT 3100, manufactured by Toyo) was used to evaluate the electrochemical characteristics of the test cell including the lithium titanium composite oxides of Examples 1, 2 and Comparative Example, and measured initial charge and discharge characteristics at 0.1C. The results are shown in FIGS. 4 and 8. 4 and 8, it can be seen that the initial capacity of the test cells including the lithium titanium composite oxides of Examples 1 and 2 is increased by 4 to 5 mAh / g than the comparative example.

Experimental Example 4 Evaluation of Rate Characteristics

Charge and discharge experiments were conducted at 0.1C to 5C with a current density of 0.2 mA / cm 2, and the results are shown in FIGS. 5, 9, and 10 and Table 1 below.

Table 1

Sample	Unit	0.1C		0.2C	0.5C	1.0C	3.0C	5.0C
		Char	Disch	Disch	Disch	Disch	Disch	Disch
Comparative example	mAh / g	173.3	170.0	168.8	164.4	155.5	129.1	110.7
	Effi (%)	98.09		99.29	96.70	91.47	75.94	65.11
Example 1	mAh / g	177.5	174.7	173.0	169.9	164.8	152.0	139.7
	Effi (%)	98.42		99.02	97.25	94.33	87.00	79.96

As shown in Table 1 and Figures 5, 9 and 10, in the case of a test cell comprising a lithium titanium composite oxide doped with a dissimilar metal of an embodiment of the present invention of the test cell containing a lithium titanium composite oxide of the comparative example Rate characteristics were improved by more than 10% than in the case, in particular, it can be seen that the high rate charge and discharge characteristics are further improved.

The method for producing a lithium titanium composite oxide doped with a dissimilar metal of the present invention and the lithium titanium composite oxide doped with a dissimilar metal prepared therein are lithium titanium composites by mixing, pulverizing and spray-drying dissimilar metals during a lithium titanium composite oxide manufacturing process. While doping different metals on the surface of the oxide, the size of the primary particles can be finely controlled than the conventional lithium titanium composite oxide, thereby providing a battery having a high initial charge and discharge efficiency and a rate characteristic of the battery.

Claims (18)

1. i) solid phase mixing of the lithium-containing compound, titanium oxide, and dissimilar metal-containing compound in a stoichiometric ratio;

   ii) dispersing the solid mixture of i) in a solvent and wet grinding until it contains particles having an average particle diameter of 0.3 μm to 0.8 μm to prepare a slurry;

   iii) spray drying the slurry of ii): and

   iv) A method for producing a lithium titanium composite oxide doped with a dissimilar metal, comprising firing the spray-dried slurry of iii).
2. The method of claim 1,

   The dissimilar metal is any one or more selected from the group consisting of Na, Zr, K, B, Mg, Al, and Zn, the method of producing a lithium titanium composite oxide doped with a dissimilar metal.
3. The method of claim 1,

   The dissimilar metal is a method of producing a lithium titanium composite oxide doped with a dissimilar metal, characterized in that Na or Zr.
4. The method of claim 3, wherein

   The Na-containing compound is sodium carbonate, sodium hydroxide or a method of producing a lithium titanium composite oxide doped with a dissimilar metal, characterized in that a mixture of sodium carbonate and sodium hydroxide.
5. The method of claim 3, wherein

   The Zr-containing compound is Zr (OH) ₄ , ZrO ₂ or a mixture thereof, characterized in that the lithium titanium composite oxide doped with a different metal.
6. The method of claim 1,

   The titanium oxide is anatase type, or a method of producing a lithium titanium composite oxide doped with a dissimilar metal, characterized in that the hydrous titanium oxide.
7. The method of claim 1

   And said lithium-containing compound is lithium hydroxide or lithium carbonate.
8. The method of claim 1,

   In the wet grinding in step ii), water is used as a solvent and wet grinding is performed at 2000 to 4000 rpm using zirconia beads.
9. The method of claim 1,

   The spray drying step of step iii) is a method of producing a lithium titanium composite oxide, characterized in that the spray hot air temperature of 250 to 300 ℃, the exhaust hot air temperature of 100 to 150 ℃ spray drying.
10. The method of claim 1,

    The calcination process of step iv) is performed by firing the spray dried body of step iii) at 700 to 800 ° C. for 5 to 10 hours under an air atmosphere. Manufacturing method.
11. It is produced by the method of any one of claims 1 to 10, the primary particles are aggregated to form secondary particles, the diameter of the primary particles is 0.3 ㎛ to 0.7 ㎛, Lithium titanium composite oxide doped with a dissimilar metal, characterized in that the diameter of the secondary particles are 5 ㎛ to 25 ㎛.
12. The method of claim 11,

    The lithium titanium composite oxide doped with the dissimilar metal is a lithium titanium composite oxide doped with a dissimilar metal, wherein the dissimilar metal is doped with more than 0 wt% and 5 wt% or less.
13. The method of claim 11,

    The lithium titanium composite oxide doped with the dissimilar metal is a lithium titanium composite oxide doped with a dissimilar metal, characterized in that the spinel structure.
14. The method of claim 11,

    The lithium titanium composite oxide doped with the dissimilar metal is a lithium titanium composite oxide doped with a dissimilar metal, wherein the main peak strength of the rutile titanium dioxide is 0 to 0.5.
15. A lithium secondary battery positive electrode comprising a lithium titanium composite oxide doped with the dissimilar metal of claim 11.
16. A negative electrode for a lithium secondary battery comprising a lithium titanium composite oxide doped with the dissimilar metal of claim 11.
17. A lithium secondary battery containing the positive electrode of claim 15.
18. A lithium secondary battery containing the negative electrode of claim 16.

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