CN104241628B - A kind of preparation method and its obtained product and purposes of the di-iron trioxide microballoon of titanium dioxide modification - Google Patents

Abstract

A preparation method of titanium dioxide-modified ferric oxide microspheres, which is to put sucrose or glucose aqueous solution into a hydrothermal reaction kettle for hydrothermal reaction at a temperature of 180-220°C, then use deionized water and ethanol to filter and wash, and dry Dry to obtain carbon spheres with uniform particle size distribution, then ultrasonically disperse the carbon spheres in the mixed solution of ferric nitrate ethanol solution and tetrabutyl titanate, stir at room temperature, stir at 60-80°C after mixing evenly, and the reaction is over Afterwards, filter and wash with absolute ethanol and deionized water, and dry at 100°C to obtain the intermediate product; the intermediate product is placed in a tube furnace at a temperature of 400-600°C and roasted for 2-4 hours in an air atmosphere to obtain titanium dioxide Modified ferric oxide microspheres. The method of the invention is easy to operate, the conditions are easy to control, and the repeatability is good, and the prepared product is used as the negative electrode material of the lithium ion battery, and the lithium ion battery produced has excellent charge and discharge cycle performance and high energy storage capacity.

Description

A kind of preparation method of ferric oxide microspheres modified by titanium dioxide and the products thereof and use

technical field

The invention relates to a ferric oxide microsphere modified by titanium dioxide, which can be used as negative electrode material of lithium ion battery.

Background technique

Due to problems such as the imminent depletion of fossil energy and the large amount of greenhouse gases generated during its use, a large number of new energy sources have entered people's field of vision, such as wind energy, tidal energy, solar energy, nuclear energy, biomass energy, etc. Most of these energy sources need to be converted into electrical energy before they can be utilized. On the other hand, it is necessary to store the generated unstable electric energy before it can be utilized. Therefore, mobile power sources have been developed rapidly. Among them, lithium-ion secondary batteries have been widely used in small portable electronic devices such as mobile phones, laptops/tablets, etc., due to their high specific capacity and energy density, long cycle life, high working voltage, and no memory effect. Power sources such as electric vehicles, and large-scale energy storage sources such as power stations have also shown good potential, and are expected to replace traditional nickel-cadmium and lead-acid batteries and become the dominant green chemical power source. The commercial lithium-ion battery cathode materials on the market are mainly: lithium cobaltate, lithium manganese oxide, lithium iron phosphate and nickel-cobalt lithium manganese oxide ternary materials; the commercially used negative electrode materials are mainly graphite materials. Researchers around the world are conducting in-depth research and development on new materials that can be applied to lithium-ion battery electrodes.

In commercial Li-ion batteries, the production cost is mainly derived from the electrode materials. Therefore, how to prepare electrode materials with low price, environmental friendliness and excellent electrochemical performance has become the top priority for the development of lithium-ion batteries. As far as negative electrode materials are concerned, commercially used graphite occupies a very large market share due to its low price and stable cycle performance. However, due to its low specific capacity (theoretical specific capacity is 372mAh/g, the actual specific capacity is not higher than 350mAh/g), and the potential of lithium intercalation is close to that of metal lithium, lithium dendrites are easily formed during long-term cycling, resulting in battery A short circuit may even cause serious consequences such as fire and explosion. Based on this, the research and development of new anode materials has a good prospect.

Metal oxides whose working mechanism is a "transformation" reaction, iron, manganese, molybdenum and other oxides have entered the field of vision of the majority of scientific researchers due to their high theoretical specific capacity, low price, environmental friendliness and abundant reserves. Taking ferric oxide as an example, its theoretical specific capacity is 1005mAh/g, almost three times that of graphite, and iron, as the second most abundant metal element in the earth's crust, exists widely in nature and is very easy to obtain. However, due to its "transformation" working mechanism, during the lithium cycle, the volume changes greatly, which easily makes the material structure pulverized, and its poor ion and electronic conduction performance also makes the cycle performance of the battery poor, which ultimately hinders the lithium battery. its practical application. In response to the above problems, scientific researchers have carried out exquisite structural design of materials, such as David Lou et al. prepared hollow spheres of ferric oxide by microemulsion hydrothermal method (J.Am.Chem.Soc.2011,133,17146– 17148), after testing, the battery charge and discharge cycle performance of this material has been greatly improved.

As a metal oxide with an "intercalation" working mechanism, titanium dioxide has very good lithium cycle performance, but its theoretical specific capacity is relatively low. It is an innovative composite oxide structure design to embed titanium dioxide on the spherical shell of the ferric oxide hollow sphere, and suppress its structural pulverization through the mesoscopic synergistic strengthening effect of titanium dioxide and ferric oxide.

Contents of the invention

The object of the present invention is to provide a preparation method of titanium dioxide-modified ferric oxide microspheres, the prepared product and its use as a lithium ion battery negative electrode material.

Technical scheme of the present invention is as follows:

A preparation method of ferric oxide microspheres modified by titanium dioxide, it comprises the following steps:

Step 1. Put the sucrose or glucose aqueous solution with a concentration of 1.5-3 mol/L into the hydrothermal reaction kettle and react for 1-4 hours at a temperature of 180-220°C. Under drying, to obtain carbon spheres with uniform particle size distribution;

Step 2. Ultrasonic disperse the prepared carbon spheres in a mixed solution of 80ml ethanol solution with a ferric nitrate concentration of 1.5-5mol/L and 1-5ml tetrabutyl titanate, stir magnetically at room temperature for 0.5-2 hours, and wait to mix After uniformity, stir magnetically at 60-80°C for 4-12 hours. After the reaction is completed, filter and wash with absolute ethanol and deionized water, and dry at 100°C to obtain an intermediate product;

Step 3. Put the intermediate product obtained in step 2 into a tube furnace at a temperature of 400-600° C. and roast for 2-4 hours in an air atmosphere to prepare titanium dioxide-modified ferric oxide microspheres.

A titanium dioxide-modified ferric oxide microsphere prepared by the above-mentioned preparation method.

The application of the titanium dioxide-modified ferric oxide microspheres as the negative electrode material of the lithium-ion battery in the preparation of the lithium-ion battery.

The invention uses the carbon self-sacrificing template method to prepare the intermediate product, and then roasts the intermediate product under the air atmosphere to generate titanium dioxide-modified ferric oxide microspheres. The method is simple and repeatable, and the preparation process is non-toxic and harmless. The finished product has high lithium storage capacity and good cycle performance.

The carbon microspheres prepared by the invention have uniform appearance, uniform particle size distribution, and a large number of functional groups and micropores on the surface, which can allow the later mixing solution to immerse. The temperature, time, and concentration difference of solution diffusion are directly related to the depth of immersion into the carbon spherical shell, that is, the thickness of the hollow spherical shell in the product, and the thickness of the spherical shell determines the electrochemical performance of the material.

The volume ratio of tetrabutyl titanate to ethanol solution in the mixed solution is 1.25 to 6.25:100, which determines the ratio of titanium dioxide and iron oxide in the final product, and the addition of an appropriate amount of titanium dioxide will improve the electrochemical performance of the material. properties, but if too much titanium dioxide is added, its specific capacity will drop significantly.

The roasting atmosphere of the intermediate product is air, the roasting temperature is 400-600° C., and the holding time is 2-4 hours. The above conditions are to completely remove the carbon template in the product to obtain a metal oxide product with higher crystallinity and specific surface area. The particle diameter of the prepared microsphere is about 20 nanometers.

The lithium ion battery prepared by using the titania-modified ferric oxide microspheres of the invention as the negative electrode material has high storage energy and good charge-discharge cycle performance.

Description of drawings

Figure 1 is the SEM and TEM images of the product, from which it can be seen that the appearance of the product is a hollow microsphere with a diameter of about 2 μm and a shell thickness of about 500 nm. Its shape is uniform and its structure is stable. The upper left of Figure 1 is the single SEM image of the product, and it can be seen that it is a hollow microsphere. The upper right is the SEM image of the aggregated product, and it can be seen that its appearance is uniform. The lower left is the macroscopic SEM image of a large number of products gathered. It can be seen that the products as a whole are gathered together and the size distribution is uniform. The lower right is the single TEM image of the product. It can be seen from the figure that the outer surface of the microspheres is pompom-like.

Figure 2 is the EDX-mapping image of the product, from which it can be seen that the microspheres are composed of Ti/Fe/O elements, and the elements are evenly distributed.

In Figure 3, a is the electrochemical cycle performance curve of the product made into a half-cell at a voltage of 0.005-3V at a rate of 200mA/g, and b is the comparison curve of ordinary ferric oxide. According to Figure 3, the material is relatively Compared with ordinary ferric oxide, the cycle performance and capacity have been greatly improved, and there is still a specific capacity of nearly 1000 mAh per gram after 100 cycles.

Figure 4 is the XRD spectrum of the product. It can be seen from the spectrum that the crystallinity of its ferric oxide is very good. It can be seen from Scherrer's formula that its grain size is about 20 nanometers. Since the amount of titanium dioxide used for modification is very small, and its particles It may be small, so the crystal information of titanium dioxide cannot be seen in the XRD pattern.

Figure 5 is the result of the specific surface area of the product. According to calculation, the product still has a specific surface area of 50m ² /g after being calcined at 550°C for 4 hours, and there are mesopores with an average pore diameter of 14nm.

detailed description

In order to clearly explain the purpose of the present invention, the technical scheme and the goal of product characteristic, the present invention will be further described below in conjunction with embodiment

Example 1

1) Synthesis of self-sacrificing carbon sphere template: Put 100ml of deionized water into a 150ml hydrothermal kettle, weigh 52g of sucrose, dissolve it in deionized water, seal the reaction kettle and place it in an oven at 200°C, heat for 2 Take it out after 1 hour, wash it with alcohol for 5 times after suction filtration, and put it in an oven at 80°C overnight.

2) Synthesis of the intermediate product: add 80ml of absolute ethanol to the beaker, weigh 60.2g of ferric nitrate nonahydrate and dissolve it in it, after proper heating and magnetic stirring to make it fully dissolved, add 2ml of tetrabutyl titanate, magnetically stir for 30 minute. Another 0.8 g of carbon spheres was put into the mixed solution, heated at 80°C for 4 hours, filtered with suction, washed with water and alcohol, and dried in an oven at 100°C to obtain an intermediate product.

3) Obtaining the final product: put the intermediate product into a tube furnace, raise the temperature to 500°C in an air atmosphere, keep it warm for 3 hours, and then cool down with the furnace to obtain the final product titanium dioxide-modified ferric oxide microspheres.

4) Take 160 mg of the product, grind and mix it with 20 mg of conductive agent acetylene black for 10 minutes, and pour it into a solution of 20 mg of binder polyvinylidene fluoride (PVDF) and 1 ml of N-methyl-pyrrolidone (NMP) that have been mixed uniformly before to obtain a slurry material. The slurry was evenly coated on the copper current collector, and dried at 80°C. Afterwards, punching was carried out, and the punched negative electrode sheet was vacuum-dried at 120° C., and then put into a glove box. : the lithium ion battery negative pole piece, diaphragm, lithium sheet that will make are laminated successively, and with the ethylene carbonate that contains the lithium hexafluorophosphate (LiPF6) of 1 mol/liter: Methyl ethyl carbonate: diethyl carbonate (EC/EMC/DEC) is that the electrolyte solution that is made into 1:1:1 by volume ratio fully mixes after sealing, makes 2032 type lithium-ion button batteries,

Example 2

1) Synthesis of self-sacrificing carbon sphere template: Put 100ml of deionized water in a 150ml hydrothermal kettle, weigh 60g of glucose, dissolve it in deionized water, seal the reaction kettle and place it in an oven at 200°C, heat for 3 Take it out after 1 hour, wash it with alcohol for 5 times after suction filtration, and put it in an oven at 80°C overnight.

2) Synthesis of the intermediate product: add 50ml of absolute ethanol into the beaker, weigh 60.2g of ferric nitrate nonahydrate and dissolve it in it, after proper heating and magnetic stirring to make it fully dissolved, add 1ml of tetrabutyl titanate, magnetically stir for 30 minute. Another 0.6 g of carbon spheres was put into the mixed solution, heated at 80°C for 4 hours, filtered with suction, washed with water and alcohol, and dried in an oven at 100°C to obtain an intermediate product.

3) Obtaining the final product: Put the intermediate product into a tube furnace, raise the temperature to 550° C. in an air atmosphere, keep it warm for 2 hours, and then cool down with the furnace to obtain the final product titanium dioxide-modified ferric oxide microspheres. Take 160 mg of the product, grind and mix it with 20 mg of conductive agent acetylene black for 10 minutes, and pour it into a solution of 20 mg of binder polyvinylidene fluoride (PVDF) and 1 ml of N-methyl-pyrrolidone (NMP) that have been mixed uniformly before to obtain a slurry. The slurry was evenly coated on the copper current collector, and dried at 80°C. Afterwards, punching was carried out, and the punched negative electrode sheet was vacuum-dried at 120° C., and then put into a glove box. : the lithium ion battery negative pole piece, diaphragm, lithium sheet that will make are laminated successively, and with the ethylene carbonate that contains the lithium hexafluorophosphate (LiPF6) of 1 mol/liter: methyl ethyl carbonate: diethyl carbonate (EC/EMC/DEC) by volume ratio is that the electrolyte solution that is made into 1:1:1 fully mixes after sealing, makes 2032 type lithium ion button batteries,

Example 3

1) Synthesis of self-sacrificing carbon sphere template: Put 100ml of deionized water into a 150ml hydrothermal kettle, then weigh 62g of sucrose, dissolve it in deionized water, seal the reaction kettle and place it in an oven at 190°C, heat for 4 Take it out after 1 hour, wash it with alcohol for 5 times after suction filtration, and put it in an oven at 80°C overnight.

2) Synthesis of the intermediate product: add 100ml of absolute ethanol into the beaker, weigh 60.2g of ferric nitrate nonahydrate and dissolve it in it, after proper heating and magnetic stirring to make it fully dissolved, add 3ml of tetrabutyl titanate, magnetically stir for 30 minute. Another 1g of carbon spheres was put into the mixed solution, heated at 70°C for 8 hours, filtered by suction, washed with water and alcohol, and dried in an oven at 100°C to obtain an intermediate product.

3) Obtaining the final product: put the intermediate product into a tube furnace, raise the temperature to 400°C in an air atmosphere, keep it warm for 4 hours, and then cool down with the furnace to obtain the final product titanium dioxide-modified ferric oxide microspheres.

4) Take 160 mg of the product, grind and mix it with 20 mg of conductive agent acetylene black for 10 minutes, and pour it into a solution of 20 mg of binder polyvinylidene fluoride (PVDF) and 1 ml of N-methyl-pyrrolidone (NMP) that have been mixed uniformly before to obtain a slurry material. The slurry was evenly coated on the copper current collector, and dried at 80°C. Afterwards, punching was carried out, and the punched negative electrode sheet was vacuum-dried at 120° C., and then put into a glove box. : the lithium ion battery negative pole piece, diaphragm, lithium sheet that will make are laminated successively, and with the ethylene carbonate that contains the lithium hexafluorophosphate (LiPF6) of 1 mol/liter: Methyl ethyl carbonate: diethyl carbonate (EC/EMC/DEC) is that the electrolyte solution that is made into 1:1:1 by volume ratio fully mixes after sealing, makes 2032 type lithium-ion button batteries,

Example 4

1) Synthesis of self-sacrificing carbon sphere template: Put 100ml of deionized water in a 150ml hydrothermal kettle, weigh 90g of glucose, dissolve it in deionized water, seal the reaction kettle and place it in an oven at 220°C, heat for 1 Take it out after 1 hour, wash it with alcohol for 5 times after suction filtration, and put it in an oven at 80°C overnight.

2) Synthesis of the intermediate product: add 100ml of absolute ethanol in a beaker, weigh 60.2g of ferric nitrate nonahydrate and dissolve it in it, after proper heating and magnetic stirring to make it fully dissolved, add 4ml of tetrabutyl titanate, magnetically stir for 30 minute. Another 1.2 g of carbon spheres was put into the mixed solution, heated at 60°C for 12 hours, filtered with suction, washed with water and alcohol, and dried in an oven at 100°C to obtain an intermediate product.

3) Obtaining the final product: put the intermediate product into a tube furnace, raise the temperature to 400°C in an air atmosphere, keep it warm for 4 hours, and then cool down with the furnace to obtain the final product titanium dioxide-modified ferric oxide microspheres. 4) Take 160 mg of the product, grind and mix it with 20 mg of conductive agent acetylene black for 10 minutes, and pour it into a solution of 20 mg of binder polyvinylidene fluoride (PVDF) and 1 ml of N-methyl-pyrrolidone (NMP) that have been mixed uniformly before to obtain a slurry material. The slurry was evenly coated on the copper current collector, and dried at 80°C. Afterwards, punching was carried out, and the punched negative electrode sheet was vacuum-dried at 120° C., and then put into a glove box. : the lithium ion battery negative pole piece, diaphragm, lithium sheet that will make are laminated successively, and with the ethylene carbonate that contains the lithium hexafluorophosphate (LiPF6) of 1 mol/liter: Methyl ethyl carbonate: diethyl carbonate (EC/EMC/DEC) according to the volume ratio is 1:1:1 the electrolytic solution that is made into is fully mixed and sealed, makes 2032 type lithium-ion button batteries.

Claims (1)

1. a kind of preparation method for the di-iron trioxide microballoon that titanium dioxide applied to lithium ion battery negative material is modified, its It is characterized in：It comprises the following steps：

Step 1, by aqueous sucrose solution that concentration is 1.5-3mol/L, to be put into hydrothermal reaction kettle hydro-thermal at a temperature of 180-220 DEG C anti- After answering 1-4 hours, with deionized water and ethanol filtering and washing, dried at 80 DEG C, obtain the homogeneous carbon ball of particle diameter distribution；

Step 2, by obtained carbon ball ultrasonic disperse in Fe(NO3)39H2O concentration be 1.5-5mol/L 80ml ethanol solutions and In the mixed solution of 1-5ml butyl titanates, magnetic agitation 0.5-2 hours, to be mixed uniformly after 60-80 DEG C of magnetic force at room temperature Stir 4-12 hours, reaction uses absolute ethyl alcohol and deionized water filtering and washing after terminating, and intermediate product is made in 100 DEG C of drying；

Step 3, intermediate product made from step 2 is placed in tube furnace at a temperature of 400-600 DEG C, 2- is calcined under air atmosphere 4 hours, the di-iron trioxide microballoon of titanium dioxide modification is made.