Liquid phase preparation method of anatase/rutile composite phase TiO2 photocatalysis and energy storage material

Anatase/rutile composite phase Ti 02 photocatalysis and liquid-phase preparation method for energy storage materials Technical field [0001] The present invention relates to the technical field of photocatalytic material synthesis and lithium ion battery anode material synthesis, and specifically relates to an anatase/ A liquid phase preparation method of rutile composite phase titanium dioxide photocatalysis and energy storage materials.

BACKGROUND [0002] Titanium dioxide is an important semiconductor material with its unique physical and chemical properties. Titanium dioxide has a wide range of application prospects in the fields of photocatalysis, solar cells, lithium-ion batteries, etc., which has attracted people's attention. Studies have shown that titanium dioxide, as a photocatalyst, plays a very good role in purifying air, degrading organic matter, and treating water pollution. Titanium dioxide, as a negative electrode material for lithium-ion batteries, has excellent battery safety performance, long service life, and rapid charge and discharge. Good performance is reflected.

[0003] Titanium dioxide mainly has three crystal phase structures, namely anatase, rutile and brookite. Among them, the rutile phase is the most stable phase as the high temperature phase, while the anatase and brookite phases are the low temperature phases, which can transform to the rutile phase under high temperature annealing conditions. The basic constituent units of the three crystal phases are all [TiO6] octahedrons, and each octahedron is centered on one Ti atom and has 6 octahedrons. Surrounded by atoms, but the degree of turbulence and connection of the octahedron are not the same. Their different structures lead to their different surface activity and physicochemical properties, and their respective uses are also different. The composite phase titanium dioxide can not only improve the performance of a single material, but also introduce special properties that a single material does not have. It shows unique physical and chemical properties. It can degrade organic pollutants, reduce toxic heavy metal ions, catalyze the decomposition of water to produce hydrogen, and increase lithium. Both the rate and the stable performance of the negative electrode material of the ion battery play a significant role. At present, the development of composite phase titanium dioxide in the field of photocatalysis is relatively mature. Among them, the P25 commercial titanium dioxide powder produced by Degussa is the most widely used, with a specific surface area of 50(±15)m²/g, and the specific surface area of the anatase/rutile composite phase titanium dioxide material we prepared is about 2-3 times that of P25. Increasing the specific surface area of titanium dioxide can also improve its photocatalytic performance and the lithium storage performance of lithium-ion batteries. This is because the large specific surface area increases the contact area between titanium dioxide and the adsorbed substance and increases the number of reactive sites and the large specific surface area It will ease the changes of some substances and reduce the disintegration of the electrode material and the capacity attenuation during the cycle due to the volume expansion. A large number of research facts have shown that the titanium dioxide composite phase material has better photocatalytic performance than the single crystal phase titanium dioxide material. This is because after being excited by ultraviolet light, electrons will transition between the two crystal phases, which further hinders the photo-generated electron-hole pair. Compound. Titanium dioxide has high chemical stability and electrochemical stability. It is a potential ideal lithium-ion battery negative electrode material. Because the principles of photocatalysis and lithium-ion batteries are the use of electrons in materials, it has shown excellent performance in the field of photocatalysis. The application of the composite phase titanium dioxide material in lithium-ion batteries also has great prospects.

[0004] At present, the method of using TiCl4 as the raw material to produce composite phase titanium dioxide P25 by the gas phase method has achieved industrialized large-scale production, but the raw material cost is relatively high, and there are certain difficulties in achieving the fine adjustment of the two-phase components, and P25 is mostly used Photocatalysis, not much involved in the field of lithium battery.

SUMMARY OF THE INVENTION [0005] Based on the above shortcomings of the prior art, the technical problem solved by the present invention is to provide an anatase/rutile composite phase titanium dioxide photocatalysis with high catalytic activity and high lithium storage performance that is simple in process and can be synthesized on a large scale. Materials and

Preparation method of negative electrode material for lithium ion battery.

[0006] In order to solve the above technical problems, the present invention provides an anatase/rutile composite phase titanium dioxide photocatalytic material and a method for preparing a lithium ion battery negative electrode material, which is characterized in that it comprises the following steps:

[0007] Step 1. Mix the titanium source and the organic solvent at a molar ratio of 20: (5-13) and stir at a uniform speed for 10-20 min;

[0008] Step two, add an acidic solution to the solution obtained in step one, the volume ratio of the acidic solution and the organic solvent is 8: (2-5), uniformly stirred for 20-30min;

[0009] Step three, the reaction solution obtained in step two is placed under 180C-220C conditions to react for 20-24h;

[0010] Step four, filter the product obtained in step three to obtain the solid product, wash with absolute ethanol and centrifuge, repeat the cleaning and centrifugation process at least three times, and then dry at 40-70C;

[0011] Step 5. The product obtained in Step 4 is calcined at 300-500°C to obtain anatase/rutile composite phase titanium dioxide photocatalytic and energy storage materials.

[0012] As a preference of the above technical solution, the anatase/rutile composite phase titanium dioxide material provided by the present invention is used as a photocatalytic material. The liquid phase preparation method further includes some or all of the following technical features:

[0013] As an improvement of the above technical solution, the organic solvent is selected from one or more of benzene, toluene or p-xylene.

[0014] As an improvement of the above technical solution, the titanium source is preferably tetrabutyl titanate.

[0015] As an improvement of the above technical solution, the acidic solution is selected from hydrochloric acid or nitric acid, etc., the concentration of hydrochloric acid is 0% to 10% (excluding the case of 0% and 10%), and the concentration of nitric acid is 2% to 10 % (Excluding 2% and 10% cases).

[0016] The titanium dioxide material obtained by the above preparation method is a stack composed of small nanoparticles and nanorods, with a specific surface area of 85-150m²/g, the pore size is 7-8nm.

[0017] The basic reaction mechanism and process of the present invention are as follows: before the reaction starts, the titanium source is mixed with an organic solvent to form a uniform oil-water interface, and then acids of different concentrations are added, and then fully mixed again, the acid-water mixture hydrolyzes the titanium source Ti(OH) 4 and Ti (OH) 4 were quickly polycondensed to produce small TiO2 particles with rich -OH on the surface. As the temperature rises, it builds into a precursor of anatase and rutile composite phase TiO2 with small particle accumulations. After the precursor is calcined, the surface organic matter and amorphous matter are processed and further converted into purer anatase Ore/rutile composite phase TiO2, that is, we need to prepare the anatase/rutile composite phase titanium dioxide photocatalytic material and lithium ion battery anode material.

[0018] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0019] First of all, the present invention can adjust the two phase ratios of anatase/rutile composite phase titanium dioxide by changing the amount of acid added in the system. With the addition of organic solvents, a finer phase ratio can also be achieved, and the synthesis method is simple. Low cost, can be synthesized on a large scale, suitable for industrial production.

[0020] Second, the anatase/rutile composite phase titanium dioxide material prepared according to the present invention has a higher specific surface area, better photodegradation performance and lithium storage performance, and the degradation rate of rhodamine B dye solution is about 13 times that of single-phase titania materials, especially when anatase/rutile composite phase titania is used as a negative electrode material for lithium-ion batteries, the charge-discharge specific capacity of the composite phase is about 1-2.5 times that of the single-phase.

[0021] The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly, it can be implemented in accordance with the content, and in order to make the above and other objectives, features and advantages of the present invention more obvious. It is easy to understand that the following detailed description is given in conjunction with the preferred embodiments.

Description of the drawings

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings of the embodiments.

[0023] FIG. 1 is an SEM image of the anatase/rutile composite phase titanium dioxide material synthesized in Example 1-3 and the single phase titanium dioxide material synthesized in Comparative Example 1-2;

[0024] FIG. 1(a) is a high-resolution SEM image of an anatase/rutile composite titanium dioxide material in Example 1; FIG. 1(b) is a low-resolution anatase/rutile titanium dioxide material in Example 1 SEM image; Figure 1(.) is a high-resolution SEM image of the pure anatase titanium dioxide material in Comparative Example 1; Figure 1@) is a low-resolution SEM image of the pure anatase titanium dioxide material in Comparative Example 1; ffl1( e) is a high-resolution SEM image of the pure rutile phase titanium dioxide material in Comparative Example 2; Figure 1f) is a low-resolution SEM image of the pure rutile phase titanium dioxide material in Comparative Example 2;

[0025] FIG. 2 is an XRD pattern of the titanium dioxide material prepared in Example 1-3 and Comparative Example 1-2;

[0026] Figure 3 (a) is a graph of nitrogen adsorption-desorption curves of the titanium dioxide materials prepared in Example 1-3 and Comparative Example 1-2;

[0027] FIG. 3 (b) is a pore size distribution diagram of the titanium dioxide material prepared in Example 1-3 and Comparative Example 1-2;

[0028] FIG. 4 is a performance diagram of the photodegradable rhodamine B dye solution of the titanium dioxide material prepared in Example 1-3 and Comparative Example 1-2;

[0029] FIG. 5 (a) is a charge-discharge cycle test diagram of the lithium ion battery prepared in Example 1-3 and Comparative Example 1-2;

[0030] FIG. 5 (b) is a test diagram of the charge-discharge rate of the lithium ion battery prepared in Example 1-3 and Comparative Example 1-2.

Detailed ways

[0031] The specific embodiments of the present invention will be described in detail below, as a part of the present invention, the principles of the present invention are explained through examples, and other aspects, features and advantages of the present invention will become clear through this detailed description. Example 1

[0033] A liquid phase preparation method of anatase/rutile composite phase titanium dioxide material, the specific steps are as follows:

[0034] (1) Take 25g of tetrabutyl titanate and pour it into a 100ml polytetrafluoroethylene reactor, add 5ml of toluene into it, and stir at a constant speed for 10min;

[0035] (2) After 10 minutes, add 8 ml of a 3wt% aqueous hydrochloric acid solution to the polytetrafluoroethylene reactor in (1), and stir uniformly for 20 minutes;

[0036] (3) Step (2) After the stirring is completed, the reaction kettle is encapsulated and placed in a blast drying box, the temperature is set to 200C, and the temperature is kept for 24h;

[0037] (4) Take out the reaction kettle from the blast drying box, pour out the supernatant in the kettle to obtain a pure white solid, wash the product in turn with absolute ethanol and water, centrifuge at a speed of 5000r/min for 10min, repeat In this step, the product is cleaned three times, after cleaning, the product is placed in a 60C oven for drying;

[0038] (5) The dried product is calcined at 350C to obtain anatase/rutile composite phase titanium dioxide material.

[0039] (6) 10 mg of the anatase/rutile composite phase titanium dioxide material obtained in this example was dispersed in 100 mL with a concentration of 10^-5Disperse in mol/l rhodamine B dye solution by ultrasonic for 10 minutes to prepare a photodegradation test solution. Then, the resulting solution is subjected to dark reaction for half an hour. After the end, it is irradiated with a 300W xenon lamp, and then the photoreaction is performed for half an hour, using ultraviolet visible light. Diffuse reflectance spectrophotometer detects the concentration change of rhodamine B dye solution.

[0040] (7) The anatase/rutile composite phase titanium dioxide material obtained in this embodiment, super conductive carbon and polyvinylidene fluoride

The ene is weighed in a mass ratio of 7:2:1, and then dissolved in N-methylpyrrolidone to make the sample smooth and uniform, and then evenly smeared on the copper foil, and placed in a 60C oven to dry for about 2 hours. Place it in a vacuum drying oven at 120C to dry for 12 hours, and then cut the copper foil to a copper sheet with a diameter of 8mm with a microtome. Assemble the battery in a glove box with water and oxygen content of less than 0.1 ppm and a haze atmosphere. The battery model is CR2025. Then put the battery in a multi-channel test system for constant current charging and discharging tests.

Example 2

[0042] A liquid phase preparation method of anatase/rutile composite phase titanium dioxide material, the specific steps are as follows:

[0043] (1) Take 25g of tetrabutyl titanate and pour it into a 100ml polytetrafluoroethylene reactor, add 3ml of toluene into it, and stir at a constant speed for 10min;

[0044] (2) After 10 minutes, add 8 ml of a 2wt% aqueous hydrochloric acid solution to the polytetrafluoroethylene reactor in (1), and stir uniformly for 20 minutes;

[0045] (3) Step (2) After the stirring is completed, the reaction kettle is packaged and placed in a blast drying box, the temperature is set to 200C, and the temperature is kept for 24h;

[0046] (4) Take out the reaction kettle from the blast drying box, pour off the supernatant in the kettle to obtain a pure white solid, wash the product in turn with absolute ethanol and water, centrifuge at a speed of 5000r/min for 10min, repeat In this step, the product is cleaned three times, after cleaning, the product is placed in a 60C oven for drying;

[0047] (5) The dried product is calcined at 350C to obtain the anatase/rutile composite phase titanium dioxide material;

[0048] (6) 10 mg of the anatase/rutile composite phase titanium dioxide material obtained in this example was dispersed in 100 mL with a concentration of 10^-5Disperse in mol/l rhodamine B dye solution by ultrasonic for 10 minutes to prepare a photodegradation test solution. Then, the resulting solution is subjected to dark reaction for half an hour. After the end, it is illuminated with a 300W xenon lamp, and the photoreaction is carried out for half an hour, using ultraviolet visible light. Diffuse reflectance spectrophotometer to detect the concentration change of rhodamine B dye solution;

[0049] (7) The anatase/rutile composite phase titanium dioxide material obtained in this embodiment, super conductive carbon and polyvinylidene fluoride were weighed in a mass ratio of 7:2:1, and then dissolved in N-form In the base pyrrolidone, make the sample smooth and uniform, and then evenly smear it on the copper foil, put it in a 60C oven for about 2 hours, and then place it in a 120C vacuum drying oven for 12 hours, and then cut the copper foil to diameter with a microtome 8m_mOf copper sheet. Assemble the battery in a glove box with water and oxygen content of less than 0.1 ppm and a haze atmosphere. The battery model is CR2025. Then put the battery in a multi-channel test system for constant current charging and discharging tests.

Example 3

[0051] A liquid phase preparation method of anatase/rutile composite phase titanium dioxide material, the specific steps are as follows:

[0052] (1) Take 25g of tetrabutyl titanate and pour it into a 100ml polytetrafluoroethylene reactor, add 2ml of toluene into it, and stir at a constant speed for 10min;

[0053] (2) After 10min, add 8ml of 1wt% hydrochloric acid aqueous solution to the polytetrafluoroethylene reactor in (1), and stir uniformly for 20min;

[0054] (3) Step (2) After the stirring is completed, the reaction kettle is packaged and placed in a blast drying box, the temperature is set to 200C, and the temperature is kept for 24h;

[0055] (4) Take out the reaction kettle from the blast drying box, pour out the supernatant in the kettle to obtain a pure white solid, wash the product in turn with absolute ethanol and water, centrifuge at a speed of 5000r/min for 10min, repeat In this step, the product is cleaned three times, after cleaning, the product is placed in a 60C oven for drying;

[0056] (5) The dried product is calcined at 350C to obtain the anatase/rutile composite phase titanium dioxide material;

[0057] (6) 10 mg of the anatase/rutile composite phase titanium dioxide material obtained in this example was dispersed in 100 mL with a concentration of 10^-5Disperse in mol/l rhodamine B dye solution by ultrasonic for 10 minutes to prepare a photodegradation test solution. Then, the resulting solution is subjected to dark reaction for half an hour. After the end, it is illuminated with a 300W xenon lamp, and then the photoreaction is performed for half an hour, using ultraviolet visible light. Diffuse reflectance spectrophotometer to detect the concentration change of rhodamine B dye solution;

[0058] (7) The anatase/rutile composite phase titanium dioxide material obtained in this example, super conductive carbon and polyvinylidene fluoride were weighed in a mass ratio of 7:2:1, and then dissolved in N-form In the base pyrrolidone, make the sample smooth and even, and then evenly spread on the copper foil, put it in a 60C oven for about 2 hours, and then place it in a 120C vacuum drying oven for 12 hours, and then cut the copper foil to diameter with a microtome It is an 8mm copper sheet. Assemble the battery in a glove box with water and oxygen content of less than 0.1 ppm and a haze atmosphere. The battery model is CR2025. Then put the battery in a multi-channel test system for constant current charging and discharging tests.

[0059] Comparative Example 1

[0060] A liquid phase preparation method of anatase phase titanium dioxide material, the specific steps are as follows:

[0061] (1) Take 25g of tetrabutyl titanate and pour it into a 100ml polytetrafluoroethylene reactor, add 5ml of toluene into it, and stir at a constant speed for 10min;

[0062] (2) After 10 minutes, add 8 ml of 0% aqueous hydrochloric acid solution to the polytetrafluoroethylene reactor in (1), and stir uniformly for 20 minutes;

[0063] (3) Step (2) After the stirring is completed, the reaction kettle is packaged and placed in a blast drying box, the temperature is set to 200C, and the temperature is kept for 24 hours;

[0064] (4) Take out the reaction kettle from the blast drying box, pour out the supernatant in the kettle to obtain a pure white solid, wash the product in turn with absolute ethanol and water, centrifuge at a speed of 5000r/min for 10min, repeat In this step, the product is cleaned three times. After cleaning, the product is placed in a 60C oven for drying;

[0065] (5) The dried product was calcined at 350C to obtain the pure anatase phase titanium dioxide comparison sample;

[0066] (6) 10 mg of the anatase phase titanium dioxide material obtained in this comparative example was dispersed in 100 mL with a concentration of 10^-5Disperse in mol/l rhodamine B dye solution by ultrasonic for 10 minutes to prepare a photodegradation test solution. Then, the resulting solution is subjected to dark reaction for half an hour. After the end, it is illuminated with a 300W xenon lamp, and the photoreaction is carried out for half an hour, using ultraviolet visible light. Diffuse reflectance spectrophotometer to detect the concentration change of rhodamine B dye solution;

[0067] (7) The anatase phase titanium dioxide material obtained in this comparative example, super conductive carbon and polyvinylidene fluoride were weighed in a mass ratio of 7:2:1, and then dissolved in N-methylpyrrolidone , To make the sample smooth and uniform, and then evenly smear it on the copper foil, put it in a 60C oven to dry for about 2 hours, and then place it in a 120C vacuum drying oven for 12 hours, and then cut the copper foil to a diameter of 8m with a microtome_mOf copper sheet. Assemble the battery in a glove box with water and oxygen content of less than 0.1 ppm and a haze atmosphere. The battery model is CR2025. Then put the battery in a multi-channel test system for constant current charging and discharging tests.

[0068] Comparative Example 2

[0069] A liquid phase preparation method of rutile phase titanium dioxide material, the specific steps are as follows:

[0070] (1) Take 25g of tetrabutyl titanate and pour it into a 100ml polytetrafluoroethylene reactor, add 5ml of toluene into it, and stir at a constant speed for 10min.

[0071] (2) After 10 minutes, add 8 ml of a 16% aqueous hydrochloric acid solution to the polytetrafluoroethylene reactor in (1), and stir uniformly for 20 minutes.

[0072] (3) After the stirring is completed, the reaction kettle is packaged and placed in a blast drying box, the temperature is set to 200C, and the reaction is kept warm

24h.

[0073] (4) Take out the reaction kettle from the blast drying box, pour out the supernatant in the kettle to obtain a pure white solid, wash the product in turn with absolute ethanol and water, centrifuge at a speed of 5000r/min for 10min, repeat In this step, the product is cleaned three times, and after cleaning, the product is placed in a 60C oven for drying.

[0074] (5) The dried product was calcined at 350C to obtain the pure rutile phase titanium dioxide comparison sample.

[0075] (6) 10 mg of the rutile phase titanium dioxide material obtained in this comparative example was dispersed in 100 mL with a concentration of 10^-5Disperse in mol/l rhodamine B dye solution by ultrasonic for 10 minutes to prepare a photodegradation test solution. Then, the resulting solution is subjected to dark reaction for half an hour. After the end, it is irradiated with a 300W xenon lamp, and then the photoreaction is performed for half an hour, using ultraviolet visible light. Diffuse reflectance spectrophotometer was used to detect the concentration change of rhodamine B dye solution.

[0076] (7) The rutile phase titanium dioxide material obtained in this comparative example, super conductive carbon and polyvinylidene fluoride were weighed in a mass ratio of 7:2:1, and then dissolved in N-methylpyrrolidone to make The sample becomes smooth and uniform, and then evenly spread on the copper foil, put it in a 60C oven and dry for about 2 hours, then place it in a 120C vacuum drying oven for 12 hours, and then cut the copper foil to a copper sheet with a diameter of 8mm with a microtome . Assemble the battery in a glove box with water and oxygen content of less than 0.1 ppm and a haze atmosphere. The battery model is CR2025. Then put the battery in a multi-channel test system for constant current charging and discharging tests.

[0077] It can be seen from FIG. 1 that in the large-area porous titania material prepared in Example 1, Comparative Example 1-2, titania is a accumulation of small particles with different sizes, with a particle size of about 10-100 nm.

[0078] FIG. 2 is an XRD pattern of the titanium dioxide prepared in Example 1-3 and Comparative Example 1-2. It can be seen that the titanium dioxide material prepared in Example 1-3 is anatase/rutile composite crystal form, and Comparative Example 1 The prepared titanium dioxide material is an anatase single phase, and the titanium dioxide material prepared in Comparative Example 2 is a rutile single phase.

[0079] FIG. 3 (a) is a graph showing the nitrogen adsorption curve of titanium dioxide prepared in Example 1-3 and Comparative Example 1-2, and FIG. 3 (b) is a graph prepared in Example 1-3 and Comparative Example 1-2 The pore size distribution diagram of titanium dioxide. It can be seen from the test results that the specific surface area of the composite phase titanium dioxide material prepared in Examples 1-3 is 85-150m²/g, the pore size is 7nm, the specific surface area and pore size of the anatase phase titanium dioxide material prepared in Comparative Example 1 are close to those of Example 3, and the specific surface area of the rutile phase titanium dioxide material prepared in Comparative Example 2 is the smallest, which is 38m²/g, there is no pore size, which proves that the composite phase titanium dioxide material with higher specific surface area is prepared by this method.

[0080] FIG. 4 is a performance diagram of the photodegradable rhodamine B dye liquor of the titanium dioxide materials prepared in Examples 1-3 and Comparative Examples 1-2, in which the photocatalytic degradation of the composite phase titanium dioxide material of the rhodamine B dye liquor The performance is better than the performance of the prepared single-phase titanium dioxide sample, by the formula In (c0/c) =kt (co-the initial concentration of the dye solution mol/L; c-the concentration of the dye solution in a certain stage mol/L; k degradation rate min -¹ ; T-degradation time min) calculated k Example 1 = 0.04283min-¹, k Example 2 = 0.03955min-¹, k Example 3 = 0.0412min", k Comparative Example 1 = 0.0120^^-¹^Comparative Example 2 = 0.01413min", the photodegradation rate constant of Rhodamine B solution of composite phase titanium dioxide material is about 1-3 times that of pure anatase phase and pure rutile phase titanium dioxide.

[0081] FIG. 5 (a) is a graph showing the charge-discharge cycle test performance of the lithium ion battery of titanium dioxide prepared in Example 1-3 and Comparative Example 1-2, and FIG. 5 (b) is Example 1-3 and Comparative Example 1 -2 The prepared titanium dioxide lithium ion battery charge and discharge rate test performance graph. It can be seen from Figure 5 that the lithium storage performance of the composite phase titanium dioxide is better than that of the prepared single-phase titanium dioxide sample. The material cycle performance is good, the capacity retention rate is high, the charge-discharge specific capacity is highly overlapped, and the coulombic efficiency is about 99%. , Its charge-discharge specific capacity is about 1-2.5 times that of single-phase titanium dioxide.

[0082] In addition, experimental data from different examples show that as the acid reaction concentration increases, the ratio of rutile and anatase of the material continues to increase, until the pure anatase phase titanium dioxide is completely transformed into pure rutile phase titanium dioxide.

[0083] The raw materials listed in the present invention, as well as the upper and lower limits and interval values of the raw materials of the present invention, and the upper and lower limits and interval values of the process parameters (such as temperature, time, etc.) can realize the present invention. List the examples one by one.

[0084] The above are the preferred embodiments of the present invention. Of course, the scope of rights of the present invention cannot be limited by this. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention Several improvements and changes can also be made, and these improvements and changes are also regarded as the protection scope of the present invention.