CN112038625A - A kind of lithium titanate anode material and preparation method thereof - Google Patents

Abstract

The invention discloses a lithium titanate negative electrode material and a preparation method thereof, and relates to the technical field of lithium ion batteries. The porous ceramics are soaked in the mixed solution; the porous ceramics after soaking are taken out, heated by microwave to gel and burn, and then the porous ceramics are separated to obtain the lithium titanate precursor powder; Lithium titanate precursor powder is sintered to obtain lithium titanate powder. The lithium titanate powder prepared by the invention is fluffy, easy to pulverize, has small particle size and narrow distribution, high activity, excellent electrochemical performance, short synthesis time and high yield in the whole preparation process.

Description

A kind of lithium titanate anode material and preparation method thereof

technical field

The invention relates to the technical field of lithium ion batteries, in particular to a lithium titanate negative electrode material and a preparation method thereof.

Background technique

At present, most commercial lithium-ion battery anode materials use various carbon materials, but the potential of the carbon anode is very close to the standard potential of lithium. When the battery is overcharged, metal lithium may precipitate on the surface of the carbon electrode to form dendrites and cause safety problems. And its fast charging and discharging ability is not strong, it is not suitable for equipment with instantaneous high current. The electrode potential of spinel-structured lithium titanate relative to lithium metal is 1.55v (Li/Li ⁺ ), and the theoretical capacity is 175mAh/g. The insertion and de-intercalation of Li ⁺ has almost no effect on the structure of the material. It has excellent cycle performance, stable discharge voltage, high lithium intercalation potential and is not easy to cause metal lithium precipitation. It can be used in the stable voltage range of most liquid electrolytes and has high coulombic efficiency. , Wide source of materials, clean and environmentally friendly and other excellent characteristics. Lithium titanate has the characteristics of more charging times, faster charging process and safer charging necessary for the next generation of lithium-ion batteries. In addition, lithium titanate also has an obvious charge-discharge platform, the platform capacity can reach more than 90% of the discharge capacity, and there is an obvious voltage mutation at the end of charge and discharge.

The method for preparing spinel-structured lithium titanate mainly adopts high-temperature solid-phase synthesis. The advantages of this method are that the process is simple and easy to realize industrialization. However, because the reactants need to be mixed for a long time and are not easy to be mixed uniformly, the obtained product has a large particle size and a poor distribution. Uniform and irregular in morphology, so there is a problem of insufficient batch stability. Hydrothermal method and spray pyrolysis method can also directly synthesize lithium titanate with spinel structure, and it is relatively easy to control the morphology and particle size of the material, but these two methods require high equipment, are difficult to operate, and are difficult to achieve industrialization. . The products prepared by the sol-gel method have high purity, good uniformity and low heat treatment temperature, but the method has a long production cycle and low yield, and is not easy to industrialize production.

SUMMARY OF THE INVENTION

Based on the technical problems existing in the background technology, the present invention proposes a lithium titanate negative electrode material and a preparation method thereof. The obtained lithium titanate powder is fluffy, easy to pulverize, small in particle size, narrow in distribution, high in activity, and excellent in electrochemical performance. .

The preparation method of a lithium titanate negative electrode material proposed by the present invention comprises the following steps:

S1, adding titanium source and lithium source to anhydrous alcohol solution, then adding styrene, divinyl, and initiator, and mixing to obtain a mixed solution;

S2, infiltrate the porous ceramic in the mixed solution;

S3, taking out the porous ceramic after soaking, heating it with microwave to gel and burning, and then separating the porous ceramic to obtain the lithium titanate precursor powder;

S4, sintering the lithium titanate precursor powder to obtain the lithium titanate powder.

Preferably, in S1, the titanium source is titanium tetrachloride or tetrabutyl titanate.

Preferably, in S1, the lithium source is any one of lithium chloride, lithium nitrate, and lithium oxalate.

Preferably, in S1, the anhydrous alcohol solution is methanol or ethanol; preferably, the initiator is tert-butyl peroxybenzoate.

Preferably, in S1, the molar ratio of the titanium source and the lithium source is n _Li : n _Ti =4:4.5-5.0; preferably, the weight ratio of divinylbenzene and styrene is 1:2-10; The weight concentration of the anhydrous alcohol solution of ethylene and divinylbenzene is 1-5%; preferably, the added amount of the initiator is 0.05-0.2% of the weight sum of divinylbenzene and styrene.

Preferably, in S2, the material of the porous ceramic is any one of zirconia, alumina, silicon carbide, silicon nitride, and zirconium diboride; preferably, the pore size of the porous ceramic is 25-50 μm, and the porosity is 40 ~60%.

Preferably, in S2, infiltration is performed for 3-5 min.

Preferably, in S3, the microwave is heated to 80-85°C; preferably, the microwave power is 400-600W.

Preferably, in S4, the sintering is calcined at 700-900° C. for 5-10 hours in an air atmosphere.

The present invention also provides a lithium titanate negative electrode material prepared by the above method.

Beneficial effects: the present invention utilizes the in-situ polymerization reaction of styrene and divinylbenzene to form a polymer network to fix metal ions lithium and titanium, and the raw materials can be uniformly mixed at the molecular level; the porous ceramic has a multi-wall three-dimensional cross structure, which can be well The reactant solution is absorbed in its micron-scale cavity, heated by microwave, and the heating is uniform, avoiding the appearance of gel agglomerates, and the combustion reaction is restricted to occur in the pores with a higher temperature, avoiding the reaction during the combustion process. ejection and loss of material. The lithium titanate powder prepared by the invention is fluffy, easy to pulverize, has small particle size and narrow distribution, high activity, excellent electrochemical performance, short synthesis time and high yield in the whole preparation process.

Description of drawings

Fig. 1 is the SEM image of the lithium titanate powder prepared in Example 1 of the present invention;

Fig. 2 is the XRD pattern of the lithium titanate powder obtained in Example 1 of the present invention;

3 is a charge-discharge curve diagram of the lithium titanate powder prepared in Example 1 of the present invention as a negative electrode material; wherein a is 0.2C, b is 1C, c is 3C, d is 5C, and e is 10C.

Detailed ways

Hereinafter, the technical solutions of the present invention will be described in detail through specific embodiments.

Example 1

(1) dissolving styrene and divinylbenzene in absolute ethanol, stirring uniformly, then adding tert-butyl peroxybenzoate, stirring uniformly, to obtain solution A; wherein, in solution A, the mixture of styrene and divinylbenzene The weight concentration sum is 1%, the weight ratio of styrene and divinylbenzene is 2:1, and the addition amount of tert-butyl peroxybenzoate is 0.05% of the weight sum of divinylbenzene and styrene;

(2) adding titanium tetrachloride and lithium nitrate into the absolute ethanol solution, stirring evenly, to obtain solution B; wherein, the metal ion concentration in solution B is a solution of 0.05mol/L, n _Li : n _Ti =4 : 4.5;

(3) mixing solution A and solution B in proportion to obtain a mixed solution; wherein, the weight sum of styrene and divinylbenzene in solution A: the sum of the metal oxides in solution B (calculated as Li ₄ Ti ₅ O ₁₂ ) weight = 1:5;

(4) The alumina porous ceramics with a pore size of 25 microns and a porosity of 60% were soaked in the mixed solution for 3 minutes, taken out, the microwave power was 400W, and the microwave was heated to 80 ° C until the infiltration solution gradually gelled and burned, and then The porous ceramics are separated, and the lithium titanate precursor powder is collected;

(5) The lithium titanate precursor powder was raised from room temperature to 550 °C at a heating rate of 3 °C/min in an air atmosphere, and kept for 5 h to decompose some carbonates in the solution, and then the temperature was increased at 2 °C/min. The heating rate is raised to 700° C., the temperature is kept for 5 hours, and then naturally cooled to room temperature to obtain the required lithium titanate powder.

Fig. 1 is the SEM of the product obtained by the present embodiment, it can be seen that the primary particle size is distributed at 200-500nm, indicating that the obtained product has a small particle size and a narrow particle size distribution; Fig. 2 is the XRD of the product obtained by the present embodiment, and diffraction peaks can be seen Sharp, indicating that the obtained product is a single lithium titanate phase, and the product crystallizes well; Excellent discharge performance, especially rate performance, the discharge capacity of 0.2C is greater than 165mAh/g, the discharge capacity of 3C is greater than 155mAh/g, and the discharge capacity of 10C is greater than 135mAh/g.

Example 2

(1) dissolving styrene and divinylbenzene in absolute ethanol, stirring uniformly, then adding tert-butyl peroxybenzoate, stirring uniformly, to obtain solution A; wherein, in solution A, the mixture of styrene and divinylbenzene The weight concentration sum is 5%, the weight ratio of styrene and divinylbenzene is 10:1, and the addition amount of tert-butyl peroxybenzoate is 0.2% of the weight sum of divinylbenzene and styrene;

(2) adding titanium tetrachloride and lithium nitrate into the absolute ethanol solution, stirring evenly, to obtain solution B; wherein, the metal ion concentration in solution B is a solution of 0.05mol/L, n _Li : n _Ti =4 : 5.0;

(3) Mix solution A and solution B in proportion to obtain a mixed solution; wherein, the weight sum of styrene and divinylbenzene in solution A: the sum of the metal oxides in solution B (calculated as Li ₄ Ti ₅ O ₁₂ ) weight = 1:5;

(4) The alumina porous ceramics with a pore size of 50 microns and a porosity of 40% were soaked in the mixed solution for 5 minutes, taken out, the microwave power was 600 W, and the microwave was heated to 85 ° C until the infiltration solution gradually gelled and burned, and then The porous ceramics are separated, and the lithium titanate precursor powder is collected;

(5) Under the air atmosphere, the lithium titanate precursor powder was raised from room temperature to 550°C at a heating rate of 3°C/min, kept for 5h, and then raised to 900°C at a heating rate of 2°C/min, kept for 10h, Then naturally cooled to room temperature to obtain the desired lithium titanate powder.

Example 3

(1) dissolving styrene and divinylbenzene in absolute ethanol, stirring uniformly, then adding tert-butyl peroxybenzoate, stirring uniformly, to obtain solution A; wherein, in solution A, the mixture of styrene and divinylbenzene The weight concentration sum is 2.5%, the weight ratio of styrene and divinylbenzene is 4:1, and the addition amount of tert-butyl peroxybenzoate is 0.1% of the weight sum of divinylbenzene and styrene;

(2) adding titanium tetrachloride and lithium nitrate into the absolute ethanol solution, stirring evenly, to obtain solution B; wherein, the metal ion concentration in solution B is a solution of 0.05mol/L, n _Li : n _Ti =4 : 4.7;

(3) Mix solution A and solution B in proportion to obtain a mixed solution; wherein, the weight sum of styrene and divinylbenzene in solution A: the sum of the metal oxides in solution B (calculated as Li ₄ Ti ₅ O ₁₂ ) weight = 1:5;

(4) The alumina porous ceramics with a pore size of 40 microns and a porosity of 50% were soaked in the mixed solution for 4 minutes, taken out, the microwave power was 500 W, and the microwave was heated to 80 ° C until the infiltration solution gradually gelled and burned, and then The porous ceramics are separated, and the lithium titanate precursor powder is collected;

(5) The lithium titanate precursor powder was raised from room temperature to 550°C at a heating rate of 3°C/min in an air atmosphere, kept for 5 hours, and then raised to 700°C at a heating rate of 2°C/min, kept for 10 hours, Then naturally cooled to room temperature to obtain the desired lithium titanate powder.

Example 4

(1) dissolving styrene and divinylbenzene in absolute ethanol, stirring uniformly, then adding tert-butyl peroxybenzoate, stirring uniformly, to obtain solution A; wherein, in solution A, the mixture of styrene and divinylbenzene The weight concentration sum is 3.5%, the weight ratio of styrene and divinylbenzene is 7:1, and the addition amount of tert-butyl peroxybenzoate is 0.15% of the weight sum of divinylbenzene and styrene;

(2) adding titanium tetrachloride and lithium nitrate into the absolute ethanol solution, stirring evenly, to obtain solution B; wherein, the metal ion concentration in solution B is a solution of 0.05mol/L, n _Li : n _Ti =4 : 4.8;

(3) Mix solution A and solution B in proportion to obtain a mixed solution; wherein, the weight sum of styrene and divinylbenzene in solution A: the sum of the metal oxides in solution B (calculated as Li ₄ Ti ₅ O ₁₂ ) weight = 1:5;

(4) The alumina porous ceramics with a pore size of 40 microns and a porosity of 50% were soaked in the mixed solution for 5 minutes, taken out, the microwave power was 500 W, and the microwave was heated to 85 ° C until the infiltration solution gradually gelled and burned, and then The porous ceramics are separated, and the lithium titanate precursor powder is collected;

(5) The lithium titanate precursor powder was raised from room temperature to 550°C at a heating rate of 3°C/min in an air atmosphere, kept for 5 hours, and then raised to 900°C at a heating rate of 2°C/min, kept for 5 hours, Then naturally cooled to room temperature to obtain the desired lithium titanate powder.

The above description is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited to this. The equivalent replacement or change of the inventive concept thereof shall be included within the protection scope of the present invention.

Claims (10)

1. a preparation method of lithium titanate negative electrode material, is characterized in that, comprises the following steps: S1, adding titanium source and lithium source to anhydrous alcohol solution, then adding styrene, divinyl, and initiator, and mixing to obtain a mixed solution; S2, infiltrate the porous ceramic in the mixed solution; S3, taking out the porous ceramic after soaking, heating it with microwave to gel and burning, and then separating the porous ceramic to obtain the lithium titanate precursor powder; S4, sintering the lithium titanate precursor powder to obtain the lithium titanate powder. 2 . The method for preparing a lithium titanate negative electrode material according to claim 1 , wherein, in S1 , the titanium source is titanium tetrachloride or tetrabutyl titanate. 3 . 3. The preparation method of lithium titanate negative electrode material according to claim 1 or 2, wherein, in S1, the lithium source is any one of lithium chloride, lithium nitrate, and lithium oxalate. 4. The preparation method of lithium titanate negative electrode material according to any one of claims 1-3, wherein in S1, the anhydrous alcohol solution is methanol or ethanol; preferably, the initiator is benzene peroxide tert-Butyl formate. 5 . The method for preparing a lithium titanate negative electrode material according to claim 1 , wherein in S1 , the titanium source and the lithium source are in a molar ratio n _Li : n _Ti =4:4.5-5.0; 5 . Preferably, the weight ratio of divinylbenzene to styrene is 1:2 to 10; preferably, the weight concentration of the anhydrous alcohol solution of styrene and divinylbenzene is 1 to 5%; The added amount is 0.05-0.2% of the weight sum of divinylbenzene and styrene. 6. The preparation method of lithium titanate negative electrode material according to any one of claims 1-5, wherein in S2, the material of the porous ceramic is zirconia, alumina, silicon carbide, silicon nitride, diboron Any one of zirconium oxide; preferably, the pore size of the porous ceramic is 25-50 μm, and the porosity is 40-60%. 7. The preparation method of lithium titanate negative electrode material according to any one of claims 1-6, characterized in that, in S2, soaking for 3-5min. 8 . The method for preparing a lithium titanate negative electrode material according to claim 1 , wherein in S3 , the microwave is heated to 80-85° C.; preferably, the microwave power is 400-600W. 9 . 9 . The method for preparing a lithium titanate negative electrode material according to claim 1 , wherein in S4 , the sintering is calcining at 700-900° C. for 5-10 hours in an air atmosphere. 10 . 10. A lithium titanate negative electrode material prepared based on the method of any one of claims 1-9.

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