CN1275342C - Preparation method of spherical Li4Ti5O12 as lithium ion cell cathode material - Google Patents

Abstract

The invention discloses a preparation method of spherical Li ₄ Ti ₅ O ₁₂ for negative electrode material of lithium ion battery, and relates to a process for preparing spherical Li ₄ Ti ₅ O ₁₂ for negative electrode material of lithium ion battery. In this method, _TiCl4 is used as a raw material, which is hydrolyzed with water to make sol A; hexamethylenetetramine and urea are dissolved with water to make solution B, and solution B is added to sol A to make a new sol. With kerosene as the medium, the mixed sol is added dropwise to the kerosene, and then heated to convert the sol into a gel and precipitate out. After separation, washing, aging and drying, a spherical precursor is obtained. Spherical Li ₄ Ti ₅ O ₁₂ is obtained by heat treatment after adding lithium. When doping, only the doped ions need to be added to sol A. The process of the invention is simple, and the prepared Li ₄ Ti ₅ O ₁₂ is spherical and has a high packing density; the process can easily realize doping and carbon doping to improve the conductivity of the product, and has great application value.

Description

Preparation method of spherical Li4Ti5O12 negative electrode material for lithium ion battery

technical field

The invention relates to a process for preparing a spherical Li ₄ Ti ₅ O ₁₂ negative electrode material for a lithium ion battery, belonging to the fields of chemical engineering and new materials.

Background technique

At present, the anode materials of lithium-ion batteries mostly use various lithium-intercalated carbon materials, but carbon materials still have some disadvantages as anode materials for lithium-ion batteries: low initial charge and discharge efficiency; interaction with electrolyte; obvious voltage hysteresis; The preparation method of the material is more complicated. Compared with the carbon negative electrode in lithium-ion batteries, although alloy negative electrode materials generally have a higher specific capacity, repeated intercalation and deintercalation of lithium lead to large volume changes of alloy electrodes during charging and discharging, and gradually pulverize and fail. Thus, the cycle performance is poor. Therefore, it is of great significance to find new anode materials that are cheap and easy to prepare, have good cycle performance, are safe and reliable, and have excellent electrochemical performance. Spinel-type lithium titanate (Li ₄ Ti ₅ O ₁₂ ) has obvious advantages as the negative electrode material of lithium-ion batteries: it is a stress-free insertion material that does not undergo structural changes during charging and discharging, and has good cycle performance; Good charging and discharging platform; the theoretical specific capacity is 175mAh/g, the actual specific capacity can reach 165mAh/g, and it is concentrated in the platform area; it does not react with the electrolyte; it is cheap and easy to prepare. However, judging from the current research results, the problems of poor conductivity and low density have not been well solved.

Contents of the invention

The purpose of the present invention is to propose a new process for preparing spherical Li ₄ Ti ₅ O ₁₂ to increase the tap density of the material, and by doping carbon and transition metal elements (such as Co, Mn, Cr, La, Y, etc.) Doping improves the conductivity of the material.

Technical scheme of the present invention is as follows:

The process for preparing spherical Li ₄ Ti ₅ O ₁₂ designed by the present invention includes the following steps:

1) Weigh a certain amount of TiCl ₄ , add deionized water dropwise under stirring conditions to hydrolyze it, and prepare TiO ₂ ·nH ₂ O sol A with a concentration of 2-5 mol/L;

2) Weigh a certain amount of urea and hexamethylenetetramine according to a mass ratio of 1 to 5:1, add deionized water to dissolve them, and prepare a solution B with a concentration of 200 to 400 g/L;

3) In the temperature range of 0°C to 10°C and under stirring conditions, add the B solution to the A sol dropwise to prepare a new sol;

4) Use kerosene as a dispersant, and add 0.1%-5% span80 therein as a surfactant; slowly add the sol prepared in step 3) into the dispersant under stirring conditions, and heat up to 70 ~80°C, keep warm for 10-20 minutes and stop heating and stirring to precipitate the gel;

5) Centrifuge the gel obtained in step 4) to obtain dry gel, wash once at 60-70°C with a 0.5-0.7% aqueous solution of tween 80 (tween80), and then wash at least two times with deionized water at room temperature. times; then aging the obtained xerogel for 24 to 48 hours with ammonia water with a concentration of 1 to 10%, drying after centrifugation to obtain a spherical precursor;

6) Weigh Li ₂ CO ₃ or LiOH according to the molar ratio of lithium to titanium of 4:5, and mix it with the spherical precursor obtained in step 5) to obtain a uniform powder;

7) The powder obtained in step 6) is heat-treated at 700° C. to 900° C. for 10 to 20 hours to obtain a spherical Li ₄ Ti ₅ O ₁₂ product.

The present invention also provides a preparation method of spherical Li ₄ Ti ₅ O ₁₂ doped with negative electrode material of lithium ion battery, which is characterized in that the method is carried out according to the following steps:

1) Weigh a certain amount of TiCl ₄ , add deionized water dropwise under stirring conditions, and make it hydrolyze to obtain a TiO ₂ ·nH ₂ O sol with a concentration of 2-5 mol/L, and then make the molar ratio M/Ti =1%-10% Weigh M(CH ₃ COO) ₂ , where M=Co, Mn, Cr, La or Y, and dissolve it in the obtained sol, which is designated as sol A;

2) Weigh a certain amount of urea and hexamethylenetetramine according to a mass ratio of 1 to 5:1, add deionized water to dissolve them, and prepare a solution B with a concentration of 200 to 400 g/L;

3) In the temperature range of 0°C to 10°C and under stirring conditions, add the B solution to the A sol dropwise to prepare a new sol;

4) Take kerosene as the medium, add 0.1%-5% Span 80 as a surfactant; slowly add the sol prepared in step 3) into the medium dropwise under stirring conditions, and heat up to 70°C after the dropwise addition is completed. ~80°C, keep warm for 10-20 minutes and stop heating and stirring to precipitate the gel;

5) centrifuging the gel obtained in step 4) to obtain a dry gel, washing once at 60-70° C. with an aqueous solution of Tuwen 80 with a concentration of 0.5-0.7%, and washing at least twice with deionized water at room temperature; then Aging the obtained dry gel with ammonia water with a concentration of 1-10% for 24-48 hours, centrifuging and drying to obtain a spherical precursor;

6) Weigh Li ₂ CO ₃ or LiOH according to the molar ratio of lithium to titanium of 4:5, and mix it with the spherical precursor obtained in step 5) to obtain a uniform powder;

7) The powder obtained in step 6) is heat-treated at 700° C. to 900° C. for 10 to 20 hours to obtain a spherical Li ₄ Ti ₅ O ₁₂ product.

The present invention also provides a preparation method of carbon-doped spherical Li ₄ Ti ₅ O ₁₂ anode material of lithium ion battery, which is characterized in that the method is carried out according to the following steps:

1) Weigh a certain amount of TiCl ₄ , add deionized water dropwise under stirring conditions to hydrolyze it, and prepare TiO ₂ ·nH ₂ O sol A with a concentration of 2-5 mol/L;

2) Weigh a certain amount of urea and hexamethylenetetramine according to a mass ratio of 1 to 5:1, add deionized water to dissolve them, and prepare a solution B with a concentration of 200 to 400 g/L;

3) In the temperature range of 0°C to 10°C and under stirring conditions, add the B solution dropwise to the A sol to prepare a new sol, first calculate the Li ₄ according to the stoichiometric ratio according to the molar amount of titanium contained in the sol The amount of Ti ₅ O ₁₂ , the mass percentage of Li ₄ Ti ₅ O ₁₂ is 1% to 10% of graphite added to the sol, and 0.1% to 5% of Triton X-100 is added as a surfactant at the same time, stirring Disperse graphite evenly in the sol;

4) Take kerosene as the medium, add 0.1%-5% Span 80 as a surfactant; slowly add the sol prepared in step 3) into the medium dropwise under stirring conditions, and heat up to 70°C after the dropwise addition is completed. ~80°C, keep warm for 10-20 minutes and stop heating and stirring to precipitate the gel;

5) centrifuging the gel obtained in step 4) to obtain a dry gel, washing once at 60-70° C. with an aqueous solution of Tuwen 80 with a concentration of 0.5-0.7%, and washing at least twice with deionized water at room temperature; then Aging the obtained dry gel with ammonia water with a concentration of 1-10% for 24-48 hours, centrifuging and drying to obtain a spherical precursor;

6) Weigh Li ₂ CO ₃ or LiOH according to the molar ratio of lithium to titanium of 4:5, and mix it with the spherical precursor obtained in step 5) to obtain a uniform powder;

7) The powder obtained in step 6) is heat-treated at 700° C.-900° C. for 10-20 hours in a tube furnace with argon or nitrogen gas to obtain a carbon-doped spherical Li ₄ Ti ₅ O ₁₂ product.

Compared with the prior art, the present invention has the following advantages and prominent effects: the technological process of the present invention is simple; a new method is adopted to prepare Li ₄ Ti ₅ O ₁₂ material; the prepared Li ₄ Ti ₅ O ₁₂ product is Spherical, high packing density; this process is easy to achieve doping and carbon doping to improve the conductivity of the product, which has great application value.

Detailed ways

Introduce the embodiment of the present invention below:

Example 1:

Weigh 10 g of TiCl ₄ into a beaker, add about 20 ml of deionized water, and hydrolyze to obtain TiO ₂ ·nH ₂ O sol A of about 2.9 mol/L. Then weigh 4.5 g each of hexamethylenetetramine (urotropine) and urea and put them into another beaker, and add about 20 ml of solution B dissolved in deionized water. Add solution B dropwise to sol A at a temperature of 10°C with stirring to prepare a new sol. Take kerosene as the medium, and then add 1% Span 80 as a surfactant, slowly add the newly prepared sol into the medium under stirring conditions, raise the temperature to 70°C after the addition is completed, and stop heating after 10 minutes of heat preservation and stirring to precipitate the gel. Centrifuge to obtain dry gel, wash once with 0.7% soil temperature 80 aqueous solution at 70°C, then wash twice with deionized water at room temperature, then age with 5% ammonia water for 24 hours, and centrifuge After drying, the spherical precursor is obtained. Li ₂ CO ₃ was weighed according to the molar ratio Li:Ti=4:5, ground and mixed with the obtained spherical precursor, and the spherical Li ₄ Ti ₅ O ₁₂ product was obtained after heat treatment at 800°C for 16 hours. The tap density of this sample was measured to be 1.55 g/cm ³ . Weigh 71.8 mg of this sample, mix the sample powder, acetylene black and PTFE in a ratio of 8:1:1, press it into an electrode sheet, use it as the positive electrode after vacuum drying, and use the pure metal lithium sheet as the negative electrode. The discharge specific capacity is 168mAh/g when the current density is 0.16mA/cm ² charge and discharge.

Example 2:

Weigh 15g of TiCl ₄ into a beaker, add about 20ml of deionized water, and hydrolyze to obtain about 4.5mol/L TiO ₂ ·nH ₂ O sol A. Then weigh 4.5 g of hexamethylenetetramine (urotropine) and 9 g of urea respectively, put them into another beaker, and add about 20 ml of solution B dissolved in deionized water. Add solution B dropwise to sol A at a temperature of 5°C under stirring conditions to prepare a new sol. Take kerosene as the medium, and then add 0.5% Span 80 as a surfactant, slowly add the newly prepared sol into the medium under stirring conditions, raise the temperature to 75°C after the addition is completed, and stop heating after 10 minutes of heat preservation and stirring to precipitate the gel. Centrifuge to obtain dry gel, wash once with 0.5% soil temperature 80 aqueous solution at 65°C, then wash twice with deionized water at room temperature, then age with 1% ammonia water for 24 hours, and centrifuge After drying, the spherical precursor is obtained. Li ₂ CO ₃ was weighed according to the molar ratio of Li:Ti=4:5, ground and mixed with the obtained spherical precursor, and the spherical Li ₄ Ti ₅ O ₁₂ product was obtained after heat treatment at 850°C for 20 hours. The tap density of this sample was measured to be 1.50 g/cm ³ . Weigh 71.8 mg of this sample, mix the sample powder, acetylene black and PTFE in a ratio of 8:1:1, press it into an electrode sheet, use it as the positive electrode after vacuum drying, and use the pure metal lithium sheet as the negative electrode. The discharge specific capacity is 167mAh/g when the current density is 0.16mA/cm ² charge and discharge.

Example 3:

Weigh 15g of TiCl ₄ into a beaker, add about 20ml of deionized water, and hydrolyze to obtain about 5mol/L TiO ₂ ·nH ₂ O sol A. Then weigh 4.5 g of hexamethylenetetramine (urotropine) and 22.5 g of urea respectively, put them into another beaker, and add about 40 ml of solution B dissolved in deionized water. Add solution B dropwise to sol A at a temperature of 10°C with stirring to prepare a new sol. Take kerosene as the medium, and then add 5% Span 80 as a surfactant, slowly add the newly prepared sol into the medium under stirring conditions, raise the temperature to 80°C after the addition is completed, and stop heating after 20 minutes of heat preservation and stirring to precipitate the gel. Centrifuge to obtain dry gel, wash once with 0.5% soil temperature 80 aqueous solution at 69 ° C, then wash twice with deionized water at room temperature, then age with 10% ammonia water for 48 hours, and centrifuge After drying, the spherical precursor is obtained. Li ₂ CO ₃ was weighed according to the molar ratio of Li:Ti=4:5, ground and mixed with the obtained spherical precursor, and the spherical Li ₄ Ti ₅ O ₁₂ product was obtained after heat treatment at 900°C for 10 hours. The tap density of this sample was measured to be 1.51 g/cm ³ . Weigh 71.8 mg of this sample, mix the sample powder, acetylene black and PTFE in a ratio of 8:1:1, press it into an electrode sheet, use it as the positive electrode after vacuum drying, and use the pure metal lithium sheet as the negative electrode. The discharge specific capacity is 166mAh/g when the current density is 0.16mA/cm ² charge and discharge.

Example 4:

The same method as in Example 1 was first prepared about 2.9mol/L TiO ₂ ·nH ₂ O sol A, weighed 0.27g of Co(CH ₃ COO) ₂ ·4H ₂ O and dissolved in sol A, and then carried out according to Co-doped spherical Li ₄ Ti ₅ O ₁₂ products were prepared in exactly the same steps as Example 1. The tap density of this sample was measured to be 1.56 g/cm ³ . The positive electrode formulation is the same as in Example 1, and the measured discharge specific capacity of the sample is 165mAh/g when the current density is 0.8mA/cm ² charge and discharge.

Example 5:

Mn-doped spherical Li ₄ Ti ₅ O ₁₂ was prepared according to the method in Example 3. The tap density of this sample was measured to be 1.53 g/cm ³ . The positive electrode formulation is the same as in Example 1, and the discharge specific capacity of the sample is 160mAh/g when the current density is 0.8mA/ ^cm2 .

Embodiment 6:

Cr-doped spherical Li ₄ Ti ₅ O ₁₂ was prepared according to the method in Example 3. The tap density of this sample was measured to be 1.54 g/cm ³ . The positive electrode formulation is the same as in Example 1, and the measured discharge specific capacity of the sample is 162mAh/g when the current density is 0.8mA/cm ² charge and discharge.

Embodiment 7:

La-doped spherical Li ₄ Ti ₅ O ₁₂ was prepared according to the method in Example 3. The tap density of this sample was measured to be 1.52 g/cm ³ . The positive electrode formulation of Example 1 is the same, and the discharge specific capacity of the sample is 161mAh/g when the current density is 0.8mA/ ^cm2 .

Embodiment 8:

The same method as in Example 1 was used to prepare mixed sols. Weigh 0.5 g of graphite and add it into the sol, and then add 1% Triton X-100 as a surfactant to disperse the graphite evenly in the sol. Then follow the same steps as in Example 1 to prepare carbon-doped spherical Li ₄ Ti ₅ O ₁₂ . The tap density of this sample was measured to be 1.46 g/cm ³ . It is the same as the positive electrode formulation of Example 1, and the discharge specific capacity of the sample is 167mAh/g when the current density is 0.8mA/ ^cm2 .

Comparative Example 1:

Weighed 17.4g TiO ₂ and 6.44g _{Li 2} CO ₃ , ground and mixed them evenly, put them into a crucible, and heat-treated them in a muffle furnace at 800°C for 16 hours to prepare Li ₄ Ti ₅ O ₁₂ . The tap density of this sample was measured to be 0.72 g/cm ³ . The positive electrode formulation is the same as in Example 1, and the measured discharge specific capacity of the sample is 163mAh/g when charging and discharging at a current density of 0.16mA/cm ² .

Comparative Example 2:

Weigh 17.4g TiO ₂ , 6.44g Li ₂ CO ₃ and 1g graphite, grind and mix them evenly, put them into a crucible, and heat-treat in a tube furnace with argon at 800°C for 16 hours to prepare carbon-doped Li ₄ Ti ₅ O ₁₂ . The tap density of this sample was measured to be 0.65 g/cm ³ . The positive electrode formulation is the same as in Example 6, and the measured discharge specific capacity of the sample is 165mAh/g when the current density is 0.8mA/cm ² charge and discharge.

Comparative Example 3:

Dissolve LiOH·H ₂ O in water to prepare an aqueous solution with a concentration of 12%, then add TiO ₂ powder into the solution, dry the sol by spray drying at 110°C, and then heat-treat at 800°C for 3 hours to obtain Li ₄ Ti ₅ O ₁₂ . The tap density of this sample was measured to be 0.8 g/cm ³ . The positive electrode formulation is the same as in Example 1, and the measured discharge specific capacity of the sample is 160mAh/g when the current density is 0.16mA/cm ² .

Claims (3)

1. the spherical Li of a lithium ion battery negative material ₄Ti ₅O ₁₂The preparation method, it is characterized in that this method carries out according to the following steps:

1) takes by weighing a certain amount of TiCl ₄, under stirring condition, drip deionized water, make its hydrolysis, make the TiO that concentration is 2～5mol/L ₂NH ₂The O Sol A;

2) be to take by weighing urea and hexamethylenetetramine at 1～5: 1 by mass ratio, add deionized water and make its dissolving, make the solution B that concentration is 200～400g/L;

3) in 0 ℃～10 ℃ temperature range and under the stirring condition, the B drips of solution is added in the A colloidal sol, make new colloidal sol;

4) with kerosene be medium, the class of department 80 that adds 0.1%-5% therein is as surfactant; With the 3rd) colloidal sol that makes of step slowly is added dropwise in the medium under stirring condition, is warming up to 70～80 ℃ after being added dropwise to complete, and be incubated to stop heating and stirring after 10～20 minutes, and gel precipitation is come out;

5) centrifugation of step 4) gained gel is obtained xerogel, with concentration be 0.5～0.7% soil temperature 80 aqueous solution 60～70 ℃ of washings once, more at normal temperatures with deionized water washed twice at least; Then with concentration be 1～10% ammoniacal liquor with gained xerogel ageing 24～48 hours, dry after the centrifugation, obtain spherical presoma;

6) be that 4: 5 ratio takes by weighing Li in lithium titanium mol ratio ₂CO ₃Or LiOH, mix with the spherical presoma of step 5) gained, make uniform powder;

7) powder with the step 6) gained promptly obtains spherical Li 700 ℃～900 ℃ following heat treatments after 10～20 hours ₄Ti ₅O ₁₂Product.

2. the spherical Li that mixes of a lithium ion battery negative material ₄Ti ₅O ₁₂The preparation method is characterized in that this method carries out according to the following steps:

1) takes by weighing a certain amount of TiCl ₄, under stirring condition, drip deionized water, make its hydrolysis, make the TiO that concentration is 2～5mol/L ₂NH ₂The O Sol A takes by weighing M (CH for M/Ti=1%-10% more in molar ratio ₃COO) ₂, wherein M=Co, Mn, Cr, La or Y make in its colloidal sol that is dissolved in gained;

2) be to take by weighing urea and hexamethylenetetramine at 1～5: 1 by mass ratio, add deionized water and make its dissolving, make the solution B that concentration is 200～400g/L;

3) in 0 ℃～10 ℃ temperature range and under the stirring condition, the B drips of solution is added step 2) in the colloidal sol of preparation, make new colloidal sol;

4) with kerosene be medium, the class of department 80 that adds 0.1%-5% therein is as surfactant; With the 3rd) colloidal sol that makes of step slowly is added dropwise in the medium under stirring condition, is warming up to 70～80 ℃ after being added dropwise to complete, and be incubated to stop heating and stirring after 10～20 minutes, and gel precipitation is come out;

5) centrifugation of step 4) gained gel is obtained xerogel, with concentration be 0.5～0.7% soil temperature 80 aqueous solution 60～70 ℃ of washings once, more at normal temperatures with deionized water washed twice at least; Then with concentration be 1～10% ammoniacal liquor with gained xerogel ageing 24～48 hours, dry after the centrifugation, obtain spherical presoma;

6) be that 4: 5 ratio takes by weighing Li in lithium titanium mol ratio ₂CO ₃Or LiOH, mix with the spherical presoma of step 5) gained, make uniform powder;

7) powder of step 6) gained is promptly obtained the spherical Li that mixes after 10～20 hours 700 ℃～900 ℃ following heat treatments ₁Ti ₅O ₁₂Product.

3. the spherical Li of a lithium ion battery negative material carbon dope ₄Ti ₅O ₁₂The preparation method is characterized in that this method carries out according to the following steps:

1) takes by weighing a certain amount of TiCl ₄, under stirring condition, drip deionized water, make its hydrolysis, make the TiO that concentration is 2～5mol/L ₂NH ₂The O Sol A;

2) be to take by weighing certain amount of urea and hexamethylenetetramine at 1～5: 1 by mass ratio, add deionized water and make its dissolving, make the solution B that concentration is 200～400g/L;

3) in 0 ℃～10 ℃ temperature range and under the stirring condition, the B drips of solution is added in the A colloidal sol, make new colloidal sol, the mole according to institute's titaniferous in the colloidal sol calculates Li by stoichiometric proportion earlier ₄Ti ₅O ₁₂Amount, will account for Li ₄Ti ₅O ₁₂Mass percent be that 1%～10% graphite adds in the colloidal sol, the triton x-100 that adds 0.1%-5% simultaneously is as surfactant, stirs to make graphite be scattered in the colloidal sol equably;

4) with kerosene be medium, the class of department 80 that adds 0.1%-5% therein is as surfactant; With the 3rd) colloidal sol that makes of step slowly is added dropwise in the medium under stirring condition, is warming up to 70～80 ℃ after being added dropwise to complete, and be incubated to stop heating and stirring after 10～20 minutes, and gel precipitation is come out;

5) centrifugation of step 4) gained gel is obtained xerogel, with concentration be 0.5～0.7% soil temperature 80 aqueous solution 60～70 ℃ of washings once, more at normal temperatures with deionized water washed twice at least; Then with concentration be 1～10% ammoniacal liquor with gained xerogel ageing 24～48 hours, dry after the centrifugation, obtain spherical presoma;

6) be that 4: 5 ratio takes by weighing Li in lithium titanium mol ratio ₂CO ₃Or LiOH, mix with the spherical presoma of step 5) gained, make uniform powder;

7) with the powder of step 6) gained in the tube furnace of logical argon gas or nitrogen 700 ℃ promptly obtain carbon-doped spherical Li after-900 ℃ of following heat treatment 10-20 hours ₄Ti ₅O ₁₂Product.