A method for preparing a tin-aluminum oxide / carbon composite

Abstract

The present application relates to a kind of tin aluminum oxide / carbon composite material preparation method.The features include the following steps:(1) preparation tin, aluminum ion / conductive carbon mixed solution and precipitant solution;(2) precipitant solution is added to tin, aluminum ion / conductive carbon mixed solution with certain flow rate, and constant temperature microwave reaction is carried out;(3) after reaction, co-precipitate is filtered, washed, and dried;(4) after drying, co-precipitate is placed in resistance furnace or microwave sintering furnace and high temperature reaction is carried out in air or oxygen atmosphere, and a kind of tin aluminum oxide / carbon composite material described in the present application is obtained.The tin aluminum oxide / carbon composite material prepared in the present application is applied to lithium ion battery negative material, and the specific capacity after 100 cycles is as high as 800 mAh / g or more, and the cycle performance is good.

Description

Technical Field

[0001] This article belongs to the field of new energy materials technology, and relates to a method for preparing tin-aluminum oxide / carbon composite materials, specifically a method for preparing tin-aluminum oxide / carbon composite anode materials for lithium-ion batteries. Background Technology

[0002] Lithium-ion batteries are widely used in electronic products such as laptops, mobile phones, and electric toys due to their high energy density, long cycle life, low self-discharge rate, and environmental friendliness. Commercial lithium-ion battery anode materials are mainly graphite. Although graphite has high conductivity and long cycle life, its actual specific capacity is relatively low (~350 mAh / g), which cannot meet the requirements of high-energy-density lithium-ion power batteries. Therefore, researching and developing new high-specific-capacity alternative anode materials is one of the key ways to improve the specific energy density of lithium-ion batteries. Tin dioxide (SnO2) is an important semiconductor material with wide applications in many fields, including perovskite solar cell materials, optical glass materials, transparent conductive electrode materials, semiconductor sensor materials, and lithium (sodium)-ion battery anode materials.

[0003] As a lithium-ion battery anode material, SnO2 is inexpensive, possesses a high theoretical specific capacity (782 mAh / g), and a low and stable charge-discharge platform, making it a potential next-generation commercial anode material. However, SnO2 anode materials still face many bottlenecks that urgently need to be addressed, such as low conductivity and a large volume effect. Compared to graphite materials, SnO2 has significantly lower conductivity than carbon materials, and its volume expansion exceeds 200% during charge-discharge, easily leading to the shedding of active material and greatly affecting its rate performance and cycle performance, as well as that of composite materials. To overcome the shortcomings of tin-based anode materials in lithium storage performance, extensive research has been conducted, including the design of carbon composites, metal oxide composites, alloy composites, and nanostructure modifications, but these have not been able to effectively improve the stability of specific capacity and the volume effect. Therefore, if specific composite components can be designed to improve its conductivity and structural stability while suppressing its volume effect, its rate performance and cycle performance during charge-discharge can be effectively improved. Summary of the Invention

[0004] To improve the lithium storage performance of SnO2, this invention provides a method for preparing tin-aluminum oxide / carbon composite materials through microwave-assisted liquid-phase synthesis.

[0005] The technical solution involved in this invention is as follows: a method for preparing a tin-aluminum oxide / carbon composite material, characterized by comprising the following steps: (1) Dissolve soluble tin salts and aluminum salts in acid in a molar ratio, wherein the total molar amount of tin and aluminum ions to the molar ratio of acid is 1:0.5~1.2, and then add deionized water to prepare a tin and aluminum ion mixed solution with a metal ion concentration of 0.1~0.5 mol / L; add conductive carbon material to the above-prepared tin and aluminum ion mixed solution, and disperse it by ultrasonication or stirring to prepare a tin and aluminum ion / conductive carbon mixed solution, wherein the mass of conductive carbon material is 2%~10% of the total mass of tin aluminum oxide / carbon composite material; (2) Measure out concentrated ammonia (25%), add deionized water to prepare an ammonia solution, wherein the volume of concentrated ammonia accounts for 5 to 10% of the total volume of the solution; add n-butanol to the prepared ammonia solution so that the volume ratio of concentrated ammonia to n-butanol is 1:0.1 to 0.2, and prepare a precipitant solution. (3) Place the prepared tin and aluminum ion / conductive carbon mixed solution in a microwave reactor, microwave-assisted heating to 55-75°C, and then add the above precipitant solution to the tin and aluminum ion / conductive carbon mixed solution at a flow rate of 100-2000 mL / min, and magnetically stir for 0.5-5 minutes. (4) After the microwave reaction is completed, cool it and separate the solid and liquid components. Then wash it with deionized water until it is neutral. Then dry the precipitate in a vacuum drying oven at 80-120°C for 2-12 hours to obtain the precursor. (5) The above-mentioned precursor is placed in a box-type resistance furnace or microwave sintering furnace and reacted at high temperature in an air or oxygen atmosphere. The temperature is rapidly raised to 400℃~600℃ and held for 0.1~4 hours to obtain a tin aluminum oxide / carbon composite material of the present invention.

[0006] In step (1), the tin salt is stannous chloride and the aluminum salt is aluminum chloride.

[0007] The acid in step (1) is concentrated hydrochloric acid (36% to 38%).

[0008] The molar ratio of tin salt to aluminum salt in step (1) is 1:1 / 19~3 / 17.

[0009] The conductive carbon material in step (1) is a type of carbon nanotube or carbon nanofiber.

[0010] The beneficial effects of the present invention are as follows: (1) The present invention designs a tin-based oxide composite component to assist in the preparation of tin-aluminum oxide / carbon composite material by microwave liquid phase reaction, which has a short reaction time and high synthesis efficiency; (2) In the present invention, there is no need for hydrothermal or other operations after microwave precipitation reaction, and the precursor does not need to be ground after drying, but can be directly calcined at high temperature, which is simple and has a short cycle; (3) The tin-aluminum oxide / carbon composite anode material obtained by the present invention has good lithium storage performance. Attached Figure Description

[0011] Figure 1 The XRD pattern of the tin aluminum oxide / carbon composite material prepared according to Example 1; Figure 2 SEM image of the tin aluminum oxide / carbon composite material prepared according to Example 1; Figure 3 Cyclic performance of the tin-aluminum oxide / carbon composite material prepared according to Example 1. Detailed Implementation

[0012] Examples of the present invention are as follows, but the invention is not limited thereto.

[0013] Example 1: (1) Weigh 0.036 mol SnCl2·2H2O and 0.004 mol AlCl3 respectively and dissolve them in 4 ml of concentrated hydrochloric acid (12 mol / L), wherein the molar ratio of tin to aluminum is 9:1 and the molar ratio of metal ions to acid is 1:1.2. Then add deionized water to make up to 200 ml, wherein the concentration of metal ions in the solution is 0.2 mol / L tin and aluminum ion mixed solution; then add carbon nanotubes to the above tin and aluminum salt solution, and after thorough sonication, prepare tin and aluminum ion / carbon nanotube mixed solution, wherein the mass of carbon nanotubes is 5% of the total mass of tin aluminum oxide / carbon composite material; (2) Take 7.5 ml of concentrated ammonia (13.8 mol / L) and add it to deionized water, and add 0.75 ml of n-butanol to it, with a volume ratio of 1:0.1, and make up to 100 ml to prepare a precipitant; (3) Place the tin and aluminum ion / carbon nanotube mixed solution in a microwave reactor, microwave-assisted heating to 60°C, then add the prepared precipitant solution to the tin salt solution at 400 mL / min, and stir for 5 minutes. (4) After the microwave reaction is completed, cool and separate the solid and liquid components, wash with deionized water until neutral, and then vacuum dry the precipitate at 100°C for 6 hours to obtain the precursor. (5) The above precursor is placed in a box-type resistance furnace and reacted at high temperature in air atmosphere. The temperature is rapidly raised to 500°C and held for 2 hours to obtain a tin-aluminum oxide / carbon composite material of the present invention. (6) The phase composition and morphology of the tin aluminum oxide / carbon composite material prepared in this embodiment are as follows: Figure 1 and Figure 2 As shown, Figure 1 The composite material structure is mainly composed of SnO2 crystalline phase. Figure 2 The composite material morphology shown is spherical; Figure 3The graph shows the cycling performance of the prepared tin-aluminum oxide / carbon composite material as a lithium-ion battery anode material. In the voltage range of 0.01V to 2.5V, the specific capacity of this anode material after 100 cycles at a current density of 100 mA / g is 805.2 mAh / g, which is significantly better than the cycling performance of the pure SnO2 anode material.

[0014] Example 2: (1) Dissolve 0.057 mol SnCl2·2H2O and 0.003 mol AlCl3 in 2.5 ml concentrated hydrochloric acid (12 mol / L), wherein the molar ratio of tin to aluminum is 9.5:0.5 and the molar ratio of metal ions to acid is 1:0.5. Then add deionized water to make up to 120 ml, and the concentration of metal ions in the solution is 0.5 mol / L tin and aluminum ion mixed solution. Then add carbon nanofibers to the above tin and aluminum ion solution, and after stirring thoroughly, prepare carbon nanofiber / tin salt mixed solution, wherein the mass of carbon nanofibers is 2% of the total mass of tin aluminum oxide / carbon composite material. (2) Take 10 ml of concentrated ammonia (13.8 mol / L) and add it to deionized water, and add 2 ml of n-butanol to it. The volume ratio is 1:0.2. Make up to 100 ml to prepare a precipitant. (3) Place the carbon nanofiber / tin salt mixed solution in a microwave reactor, microwave-assisted heating to 75°C, then add the above mixed precipitant solution to the tin salt solution at 2000 mL / min, and magnetically stir for 0.5 minutes; (4) After the microwave reaction is completed, cool and separate the solid and liquid components, wash with deionized water until neutral, and then vacuum dry the precipitate at 120°C for 2 hours to obtain the precursor. (5) The above precursor is placed in a microwave sintering furnace and reacted at high temperature in an oxygen atmosphere. The temperature is rapidly raised to 600°C and held for 0.1 hours to obtain a tin-aluminum oxide / carbon composite material as described in this invention.

[0015] Example 3: (1) Dissolve 0.017 mol SnCl2·2H2O and 0.003 mol AlCl3 in 1.33 ml concentrated hydrochloric acid (12 mol / L), wherein the molar ratio of tin to aluminum is 8.5:1.5 and the molar ratio of metal ions to acid is 1:0.8. Then add deionized water to make up to 200 ml, and the concentration of metal ions in the solution is 0.1 mol / L tin and aluminum ion mixed solution. Then add carbon nanotubes to the above tin and aluminum salt solution, and after thorough sonication, prepare tin and aluminum ion / carbon nanotube mixed solution, wherein the mass of carbon nanotubes is 10% of the total mass of tin aluminum oxide / carbon composite material. (2) Take 5 ml of concentrated ammonia (13.8 mol / L) and add it to deionized water, and add 0.75 ml of n-butanol to it, with a volume ratio of 1:0.15, and make up to 50 ml to prepare a precipitant; (3) Place the carbon nanotube / tin salt mixed solution in a microwave reactor, microwave-assisted heating to 55°C, then add the above mixed precipitant solution to the tin salt solution at 100 mL / min, and magnetically stir the reaction for 3 minutes. (4) After the microwave reaction is completed, the mixture is cooled and separated into solid and liquid components. It is then washed with deionized water until neutral. The precipitate is then dried at 80°C for 12 hours to obtain the precursor. (5) The above precursor is placed in a box-type resistance furnace or microwave sintering furnace and reacted at high temperature in air atmosphere. The temperature is rapidly raised to 400°C and held for 4 hours to obtain a tin-aluminum oxide / carbon composite material as described in this invention.

Claims

1. A method for preparing a tin-aluminum oxide / carbon composite material, characterized in that, Includes the following steps: (1) Dissolve soluble tin and aluminum salts in acid, wherein the total molar amount of tin and aluminum ions to the molar ratio of acid is 1:0.5~1.2, and then add deionized water to prepare a tin and aluminum ion mixed solution with a metal ion concentration of 0.1~0.5 mol / L; add conductive carbon material to the above-prepared tin and aluminum ion mixed solution, and disperse it by ultrasonication or stirring to prepare a tin and aluminum ion / conductive carbon mixed solution, wherein the mass of conductive carbon material is 2%~10% of the total mass of tin aluminum oxide / carbon composite material; (2) Measure concentrated ammonia water and add deionized water to prepare an ammonia solution, wherein the volume of concentrated ammonia water accounts for 5 to 10% of the total volume of the solution; add n-butanol to the prepared ammonia solution so that the volume ratio of concentrated ammonia water to n-butanol is 1: 0.1 to 0.2 to prepare a precipitant solution; (3) Place the prepared tin and aluminum ion / conductive carbon mixed solution in a microwave reactor, microwave-assisted heating to 55-75°C, and then add the above precipitant solution to the tin and aluminum ion / conductive carbon mixed solution at a flow rate of 100-2000 mL / min, and magnetically stir for 0.5-5 minutes. (4) After the microwave reaction is completed, cool it and separate the solid and liquid components. Then wash it with deionized water until it is neutral. Then dry the precipitate in a vacuum drying oven at 80-120°C for 2-12 hours to obtain the precursor. (5) Place the above precursor in a box-type resistance furnace or microwave sintering furnace and carry out a high-temperature reaction in an air or oxygen atmosphere, rapidly raise the temperature to 400℃~600℃ and hold for 0.1~4 hours.

2. The method for preparing a tin-aluminum oxide / carbon composite material as described in claim 1, characterized in that, The tin salt in step (1) is SnCl2·2H2O, and the aluminum salt is AlCl3.

3. The method for preparing a tin-aluminum oxide / carbon composite material as described in claim 1, characterized in that, The acid in step (1) is concentrated hydrochloric acid.

4. The method for preparing a tin-aluminum oxide / carbon composite material as described in claim 1, characterized in that, The molar ratio of tin salt to aluminum salt in step (1) is 1:1 / 19~3 / 17.

5. The method for preparing a tin-aluminum oxide / carbon composite material as described in claim 1, characterized in that, The conductive carbon material in step (1) is a type of carbon nanotube or carbon nanofiber.

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