Hydrogenated titanium dioxide / ferroferric oxide / hollow carbon composite material with high-stability sandwich hollow structure as well as preparation method and application of hydrogenated titanium dioxide / ferroferric oxide / hollow carbon composite material
By using a sandwich-structured hollow composite material of hydrogenated titanium dioxide/iron tetroxide/hollow carbon, the problem of volume expansion of lithium-ion battery anode materials during charge and discharge is solved, improving cycle stability and conductivity, and making it suitable for the industrial production of lithium-ion battery anode materials.
Patent Information
- Application Number
- CN202511328504.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-17
- Publication Date
- 2025-12-12
AI Technical Summary
In existing lithium-ion battery anode materials, transition metal oxides are prone to volume expansion during the insertion and extraction of lithium ions, leading to structural collapse and poor cycle stability. Single TiO2 or carbon coating cannot effectively suppress volume expansion, thus affecting battery performance.
A sandwich hollow structure of hydrogenated titanium dioxide/iron oxide/hollow carbon composite material is adopted. The transition metal oxide iron oxide is used as the sandwich layer, and hollow carbon and hollow hydrogenated titanium dioxide are used as the support layers to suppress the volume expansion of iron oxide and improve the electrical conductivity.
It effectively suppresses the volume expansion of iron(III) oxide during charging and discharging, improves cycle stability and battery performance, increases the theoretical capacity and conductivity of composite materials, and is suitable for industrial mass production.
Smart Images
Figure CN121123231A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of lithium battery negative electrode material, in particular to a preparation method of lithium battery negative electrode material. BACKGROUND
[0002] At present, lithium ion battery develops rapidly, and the negative electrode capacity is close to the theoretical capacity of graphite, so it is urgent to find a negative electrode material with higher capacity. Transition metal oxides have become a kind of negative electrode material with great potential due to their high theoretical capacity. They have good ferroelectric, superconducting, piezoelectric and magnetoelastic properties, and have wide application prospects in energy storage, energy conversion, semiconductors and other fields.
[0003] However, due to the energy conversion mechanism of transition metal oxides, volume expansion easily occurs during the embedding and de-embedding of lithium ions, which leads to structure collapse and poor cycle stability. In this case, titanium dioxide (TiO2) and carbon are often used as auxiliary materials to modify the stability and conductivity of the surface of transition metal oxide materials, so as to obtain a new type of titanium dioxide and carbon containing nanocomposite, which has broad application prospects in batteries, electronics, catalysts, biomedicine, and radio waves.
[0004] At present, single TiO2 or carbon is usually used to coat transition metals. However, TiO2 itself has poor conductivity and low theoretical capacity, which will affect the intrinsic capacity (comprehensive theoretical capacity per unit volume) of the composite material. At the same time, single-layer carbon coating cannot effectively inhibit the volume expansion of Fe3O4 nanoparticles during the battery cycle process, resulting in that the battery performance cannot be cycled for a long time with high specific capacity. SUMMARY
[0005] In view of the deficiencies in the prior art, the present application provides a preparation method of a high-stability sandwich hollow structure hydrogenated titanium dioxide / ferroferric oxide / hollow carbon composite material. The prepared nanoparticles have the characteristics of regular morphology, good uniformity and high electrochemical performance.
[0006] The purpose of the present application is achieved by a preparation method of a high-stability sandwich hollow structure carbon / hydrogenated titanium dioxide sandwich mesoporous ferroferric oxide, comprising the following steps: S1, iron salt, glucose, urea, ammonium chloride and hexamethylene tetramine are added to an ethylene glycol solution, stirred to obtain a turbid solution A, then transferred to a reaction kettle for hydrothermal reaction to obtain black powder B, and the black powder B is calcined in a tube furnace under nitrogen atmosphere to obtain mesoporous ferroferric oxide nanoparticles; S2. Mesoporous iron oxide nanoparticles are added to a mixed solution of anhydrous ethanol and deionized water and stirred to disperse them evenly. Then, ammonia, formaldehyde and resorcinol are added and stirred to obtain mixed solution B. The solution is then transferred to a reaction vessel for hydrothermal reaction to obtain carbon-coated core-shell structured mesoporous iron oxide nanoparticles. S3. Carbon-coated core-shell structured mesoporous iron oxide nanoparticles are added to an acid solution of a certain concentration and stirred at high temperature to obtain hollow structured mesoporous carbon materials. S4. Add the hollow mesoporous carbon material to deionized water, anhydrous ethanol, and ammonia, and sonicate; then add tetrapropoxysilane and stir to obtain a silica-coated hollow carbon material. S5. Add the silica-coated hollow carbon material to an ethylene glycol solution, then add iron salt and hexamethylenetetramine, stir to obtain a turbid liquid C, then transfer it to a reaction vessel for hydrothermal reaction to obtain black powder D, and place the black powder D in a tube furnace under a nitrogen atmosphere to calcine to obtain double-core shell coated iron tetroxide / silica-coated hollow carbon nanoparticles. S6. Place the hollow carbon nanoparticles coated with iron oxide / silicon dioxide into an alkaline solution of a set concentration and stir to obtain hollow carbon nanoparticles coated with iron oxide with a hollow structure. S7. Hollow carbon nanoparticles coated with iron oxide are added to deionized water, anhydrous ethanol, and ammonia, and then sonicated. Tetrapropoxysilane is then added and stirred to obtain hollow carbon nanoparticles coated with silicon dioxide and iron oxide. S8. Add the hollow carbon nanoparticles coated with silica and iron oxide to anhydrous ethanol solution and stir to obtain mixed solution E. Then add tetrabutyl titanate and stir in a water bath to obtain hollow carbon nanoparticles coated with titanium dioxide, coated with silica and coated with silica. S9. Add hollow carbon nanoparticles coated with titanium dioxide, coated with silicon dioxide, coated with iron oxide, and coated with carbon to an alkaline solution, stir, then slowly add hydrochloric acid solution until no bubbles are generated, stir and filter to obtain solid powder F. S10. Solid powder F is placed in a tube furnace and calcined under a hydrogen-argon atmosphere to obtain a highly stable sandwich hollow structure hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material.
[0007] Furthermore, the iron salt in S1 is ferric chloride, ferrous sulfate, and ferric chloride hexahydrate. The mass ratio of iron salt to glucose, urea, ammonium chloride, and hexamethylenetetramine is 4~6:1:1:1:2. The hydrothermal temperature is 180℃, and the hydrothermal time is 20 h. The calcination temperature is 500℃, the heating rate from room temperature to 300℃ is 3℃ / min, the calcination time is 2 h, and the heating rate from 300℃ to 500℃ is 10℃ / min, the calcination time is 2 h.
[0008] Furthermore, the volume ratio of anhydrous ethanol to deionized water in S2 is 1:1; the molar ratio of ammonia, formaldehyde, resorcinol, and mesoporous iron(III) oxide is 0.1:0.1:0.2:2.
[0009] Furthermore, the acid solution of S3 is hydrofluoric acid with a concentration of 2 M, and the mass ratio of carbon-coated core-shell mesoporous iron oxide to hydrofluoric acid is 1:2. The mixture is stirred at 80°C for 24 h.
[0010] Furthermore, the volume ratio of anhydrous ethanol to deionized water in S4 is 1:1, and the molar ratio of ammonia and tetrapropoxysilane to hollow carbon is 0.1:1:2. The mixture is stirred at room temperature for 24 h.
[0011] Furthermore, the mass ratio of silica-coated hollow carbon to iron salt and hexamethylenetetramine in S5 is 2:4 to 6:1, the hydrothermal temperature is 180℃, and the hydrothermal time is 20 h; the calcination temperature is 450℃, the heating rate from room temperature to 300℃ is 3℃ / min, the calcination time is 2 h, and the heating rate from 300℃ to 450℃ is 10℃ / min, the calcination time is 2 h.
[0012] Furthermore, the alkaline solution of S6 is 2 M NaOH, and the mass ratio of the hollow carbon coated with iron oxide / silica to NaOH is 8:1. The solution is stirred at 60°C until the color of the solution turns slightly gray.
[0013] Furthermore, the volume ratio of anhydrous ethanol to deionized water in S7 is 1:1, and the molar ratio of ammonia and tetrapropoxysilane to hollow carbon coated with iron oxide is 0.1:1:2. The mixture is stirred at room temperature for 24 h. The volume ratio of the mixed solution E of S8 to tetrabutyl titanate is 10:1, the water bath temperature is 55℃, the water bath time is 24 h, and the molar ratio of the hollow structure of silica-coated iron oxide-coated hollow structure to tetrabutyl titanate is 5:1. The alkaline solution of S9 is 2 M NaOH, and the mass ratio of titanium dioxide-coated hollow silica / iron oxide-coated hollow carbon to NaOH is 8:1. Stir at 60℃ until the solution turns slightly gray. The S10 is calcined at 450℃, with a heating rate of 5℃ / min, for 4 hours.
[0014] A highly stable sandwich hollow structure hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material was prepared using the above-mentioned method.
[0015] An application of a highly stable sandwich hollow structure hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material for the preparation of lithium-ion battery anode materials.
[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention fabricates a composite material using a transition metal oxide (Fe3O4) as a sandwich layer and hollow carbon and hollow hydrogenated titanium dioxide as support layers to suppress the volume expansion of Fe3O4 during charge and discharge. Using a hollow carbon layer as the bottom support reduces the mass ratio of carbon in the composite material, thereby increasing its theoretical capacity. The hollow structure provides sufficient space for electrolyte transport and wetting, improving the battery's rate performance. The sandwich structure suppresses the volume expansion of Fe3O4 during charge and discharge, improving cycle stability. Simultaneously, hydrogenation of the titanium dioxide improves the material's conductivity.
[0017] The preparation process of this invention is easy to control, simple, and low in cost, making it suitable for industrial mass production; the obtained nanocomposite material has the characteristics of regular morphology and good uniformity. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0019] Figure 1 This is a TEM image of the hollow carbon of the present invention.
[0020] Figure 2 This is a TEM image of hollow carbon coated with iron oxide in the present invention.
[0021] Figure 3 This is a TEM image of the sandwich hollow structure of hydrogenated titanium dioxide / iron tetroxide / hollow carbon of the present invention.
[0022] Figure 4 This is a SEM image of the hollow carbon of the present invention.
[0023] Figure 5 This is a SEM image of hollow carbon coated with iron oxide in the present invention.
[0024] Figure 6 This is a SEM image of the hollow structure of hydrogenated titanium dioxide / iron tetroxide / hollow carbon in this invention.
[0025] Figure 7 The diagram shows the cycling performance of a sandwich-structured hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material.
[0026] Figure 8 This is a SEM image of the sandwich hollow structure of hydrogenated titanium dioxide / iron tetroxide / hollow carbon in Embodiment 2 of the present invention.
[0027] Figure 9 This is a SEM image of the sandwich hollow structure of hydrogenated titanium dioxide / iron tetroxide / hollow carbon in Embodiment 3 of the present invention. Detailed Implementation
[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0029] Example 1.
[0030] A method for preparing a sandwich-structured hollow titanium dioxide / iron tetroxide / hollow carbon alloy includes the following steps.
[0031] S1. 1.8 g of ferric chloride, 0.3 g of glucose, 0.3 g of urea, 0.3 g of ammonium chloride, and 0.6 g of hexamethylenetetramine were dissolved in 90 mL of ethylene glycol solution to obtain iron ion solution A. Solution A was subjected to hydrothermal reaction at 180 °C for 20 h, then filtered. The filter cake was washed by centrifugation with water and ethanol, respectively, and then dried to obtain black solid powder B. Black solid powder B was placed in a tube furnace and calcined in a nitrogen atmosphere at a calcination temperature of 500 °C, a heating rate of 3 °C / min from room temperature to 300 °C for 2 h, and a heating rate of 10 °C / min from 300 °C to 500 °C for 2 h to obtain mesoporous iron oxide nanomaterials.
[0032] S2. 1 g of mesoporous iron oxide nanoparticles were added to a mixed solution of 90 mL of deionized water and anhydrous ethanol (15 mL:15 mL) and magnetically stirred for 40 min. Then, 0.1 mL of 28% ammonia, 2 mL of formaldehyde and 0.8 g of resorcinol were added and stirred for 30 min to obtain a mixed solution. The mixed solution was subjected to hydrothermal reaction at 100 °C for 24 h. After filtration, the filter cake was washed by centrifugation with water and ethanol respectively. Then, the filter cake was dried to obtain a single-layer carbon-coated core-shell structured iron oxide composite material.
[0033] S3. Add 1 g of carbon-coated core-shell iron oxide to 20 mL of 2 M hydrofluoric acid solution (calculated based on a density of 1.13 g / cm³), stir at 80 °C for 24 h, and wash with deionized water until neutral to obtain hollow carbon material.
[0034] S4. Add 1 g of hollow carbon, 17.29 mL of tetrapropoxysilane and 0.12 mL of ammonia to a mixed solution of 90 mL of deionized water and anhydrous ethanol (15 mL:15 mL), stir at room temperature for 24 h to obtain silica-coated hollow carbon.
[0035] S5. 1 g of silica-coated hollow carbon composite material was added to 90 mL of ethylene glycol solution, followed by the addition of 3 g of ferric chloride and 0.5 g of hexamethylenetetramine. The mixture was stirred to obtain a mixed solution. The water bath temperature was 180℃ for 20 h to obtain ferric oxide / silica-coated hollow carbon nanocomposite material.
[0036] S6. Add 0.13 g of the hollow nano-carbon composite material coated with iron oxide / silica to 200 mL of 2M sodium hydroxide solution, stir at 60℃ until the solution turns slightly gray, and obtain the hollow iron oxide / hollow carbon composite material.
[0037] S7. Add 0.85 g of iron oxide / hollow carbon, 17.29 mL of tetrapropoxysilane and 0.12 mL of ammonia to a mixed solution of 90 mL of deionized water and anhydrous ethanol (15 mL:15 mL), stir at room temperature for 24 h to obtain a silicon dioxide-coated hollow iron oxide / hollow carbon composite material.
[0038] S8. 1 g of silica-coated hollow structure iron(III) oxide / hollow carbon composite material was added to 100 mL of anhydrous ethanol solution and stirred to obtain mixed solution E. 10 mL of tetrabutyl titanate was added to mixed solution E, and the mixture was stirred for 24 h at a water bath temperature of 55℃. The mixture was then filtered, and the filter cake was washed by centrifugation with water and ethanol respectively. The filter cake was then dried to obtain titanium dioxide-coated hollow structure silica / iron(III) oxide-coated hollow carbon nanocomposite material.
[0039] S9. Add 0.1 g of titanium dioxide-coated hollow silica / iron oxide-coated hollow carbon nanocomposite material to 200 mL of 2 M sodium hydroxide solution, stir at 60 °C until the solution turns slightly gray, to obtain solid powder F, sandwich hollow structure hydrogenated titanium dioxide / iron oxide / hollow carbon composite material.
[0040] S10. Solid powder F is placed in a tube furnace and calcined under a hydrogen-argon atmosphere (volume ratio 1:19) at a temperature of 450 °C and a heating rate of 5 °C / min for 4 h. A sandwich-structured hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material is obtained.
[0041] Reference Figures 1-3 The images show TEM images of hollow carbon, hollow carbon coated with a hollow iron oxide (Fe3O4) structure, and hollow carbon with a sandwich-like hollow structure of titanium dioxide / Fe3O4 / hollow carbon. The images show that the hollow carbon has a uniform spherical structure with a relatively complete internal hollow structure. The method of this invention can successfully prepare hollow carbon materials, reducing the mass ratio of carbon in the composite material and thus improving the intrinsic capacity of the composite. The hollow iron oxide (Fe3O4) coated hollow carbon material shows that the thickness of the iron oxide is approximately twice that of the carbon material, ensuring both the mass ratio of iron oxide in the composite and the intrinsic capacity of the composite. The presence of the core-shell structure can suppress the volume expansion of iron(III) oxide during charging and discharging. TEM images of the sandwich-structured hollow titanium dioxide / iron(III) oxide / hollow carbon composite material show that the hydrogenated titanium dioxide completely encapsulates the hollow iron(III) oxide / hollow carbon composite material, which can greatly alleviate the volume expansion of iron(III) oxide and improve the cycle performance of the electrode material. At the same time, the hydrogenation treatment of titanium dioxide greatly improves the conductivity of the composite material. The sandwich-structured hollow structure not only provides three-dimensional electron and ion channels for the composite material, but also assists the hydrogenated titanium dioxide layer and carbon layer in suppressing the volume expansion of iron(III) oxide.
[0042] Reference Figures 4-6 The images show SEM images of hollow carbon, hollow carbon coated with iron oxide (Fe3O4) in a hollow structure, and hollow carbon with a sandwich structure of titanium dioxide / Fe3O4 / hollow carbon. The structural morphology corresponds to the reference images. Figures 1-3 The conclusions are similar.
[0043] The sandwich-structured hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material prepared above was used as the anode material for half-cell button lithium-ion batteries.
[0044] Preparation process: First, prepare a slurry bottle and add 1 mL of N-methyl-2-pyrrolidone (NMP) organic solvent, 20 mg of polyvinylidene fluoride, and 20 mg of conductive carbon black sequentially. Stir thoroughly for about 20 min. Then, add 160 mg of fully ground active material sandwiched hollow structure hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material to the slurry bottle and stir for 24 h. Use a coating machine to coat the prepared slurry onto copper foil to a thickness of 60 mm, and vacuum dry the copper foil for 8 h. Subsequently, cut the copper foil into coin-sized electrode pieces and weigh the active material on each electrode. Finally, assemble CR2032 coin cells in the coin cell assembly sequence in an argon-filled glove box, using 1M LiPF6 as the electrolyte, and let stand for 24 h before conducting the corresponding tests.
[0045] Test method: A Xinwei CT-4008 battery tester was used, with a voltage range of 0.01~3.00 V and a current density of 0.3 A g. -1 Electrochemical performance testing was conducted. Figure 7 The results show that the sandwich-structured hollow titanium dioxide / iron tetroxide / hollow carbon composite material, when used as the anode material in a lithium-ion half-cell, has a capacity of 457.58 mAh g after 700 cycles. -1 This indicates that hollow carbon, hydrogenated titanium dioxide, and the sandwich hollow structure can effectively suppress the volume expansion of iron(III) oxide during battery cycling and improve its cycle stability.
[0046] Example 2: In Example 1, 1.8 g of ferric chloride was replaced with 1.8 g of ferric chloride hexahydrate, and the remaining steps were the same as in Example 1, to obtain a sandwich-structured hydrogenated titanium dioxide / ferric oxide / hollow carbon.
[0047] Example 3: In Example 1, 1.8 g of ferric chloride was replaced with 1.8 g of ferrous sulfate, and the remaining steps were the same as in Example 1, to obtain a sandwich-structured hydrogenated titanium dioxide / iron tetroxide / hollow carbon.
[0048] Figure 8 and Figure 9 SEM images of the nanoparticles from Examples 2 and 3 are shown, respectively. Both examples show the preparation of three-dimensional sandwich double-coated carbon mesh encapsulated hydrogenated titanium dioxide coated core-shell structure mesoporous iron oxide nanocomposites.
[0049] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
Claims
1. A method for preparing a highly stable sandwich hollow structure hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material, characterized in that, Includes the following steps: S1. Add iron salt, glucose, urea, ammonium chloride and hexamethylenetetramine to ethylene glycol solution and stir to obtain turbid liquid A. Then transfer to a reaction vessel for hydrothermal reaction to obtain black powder B. Place black powder B in a tube furnace and calcine under nitrogen atmosphere to obtain mesoporous iron oxide nanoparticles. S2. Mesoporous iron oxide nanoparticles are added to a mixed solution of anhydrous ethanol and deionized water and stirred to disperse them evenly. Then, ammonia, formaldehyde and resorcinol are added and stirred to obtain mixed solution B. The solution is then transferred to a reaction vessel for hydrothermal reaction to obtain carbon-coated core-shell structured mesoporous iron oxide nanoparticles. S3. Carbon-coated core-shell structured mesoporous iron oxide nanoparticles are added to an acid solution of a certain concentration and stirred at high temperature to obtain hollow structured mesoporous carbon materials. S4. Add the hollow mesoporous carbon material to deionized water, anhydrous ethanol, and ammonia, and sonicate; then add tetrapropoxysilane and stir to obtain a silica-coated hollow carbon material. S5. Add the silica-coated hollow carbon material to an ethylene glycol solution, then add iron salt and hexamethylenetetramine, stir to obtain a turbid liquid C, then transfer it to a reaction vessel for hydrothermal reaction to obtain black powder D, and place the black powder D in a tube furnace under a nitrogen atmosphere to calcine to obtain double-core shell coated iron tetroxide / silica-coated hollow carbon nanoparticles. S6. Place the hollow carbon nanoparticles coated with iron oxide / silicon dioxide into an alkaline solution of a set concentration and stir to obtain hollow carbon nanoparticles coated with iron oxide with a hollow structure. S7. Hollow carbon nanoparticles coated with iron oxide are added to deionized water, anhydrous ethanol, and ammonia, and then sonicated. Tetrapropoxysilane is then added and stirred to obtain hollow carbon nanoparticles coated with silicon dioxide and iron oxide. S8. Add the hollow carbon nanoparticles coated with silica and iron oxide to anhydrous ethanol solution and stir to obtain mixed solution E. Then add tetrabutyl titanate and stir in a water bath to obtain hollow carbon nanoparticles coated with titanium dioxide, coated with silica and coated with silica. S9. Add hollow carbon nanoparticles coated with titanium dioxide, coated with silicon dioxide, coated with iron oxide, and coated with carbon to an alkaline solution, stir, then slowly add hydrochloric acid solution until no bubbles are generated, stir and filter to obtain solid powder F. S10. Solid powder F is placed in a tube furnace and calcined under a hydrogen-argon atmosphere to obtain a highly stable sandwich hollow structure hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material.
2. The preparation method of a highly stable sandwich hollow structure hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material according to claim 1, characterized in that, The iron salt in S1 is ferric chloride, ferrous sulfate, and ferric chloride hexahydrate. The mass ratio of iron salt to glucose, urea, ammonium chloride, and hexamethylenetetramine is 4~6:1:1:1:
2. The calcination temperature is 500℃, the heating rate from room temperature to 300℃ is 3℃ / min, the calcination time is 2 h, and the heating rate from 300℃ to 500℃ is 10℃ / min, the calcination time is 2 h.
3. The method for preparing a highly stable sandwich hollow structure hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material according to claim 1, characterized in that, The volume ratio of anhydrous ethanol to deionized water in S2 is 1:1; the molar ratio of ammonia, formaldehyde, resorcinol, and mesoporous iron oxide is 0.1:0.1:0.2:
2.
4. The method for preparing a highly stable sandwich hollow structure hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material according to claim 1, characterized in that, The acid solution of S3 is hydrofluoric acid with a concentration of 2 M, and the mass ratio of carbon-coated core-shell mesoporous iron oxide to hydrofluoric acid is 1:
2.
5. The method for preparing a highly stable sandwich hollow structure hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material according to claim 1, characterized in that, The volume ratio of anhydrous ethanol to deionized water in S4 is 1:1, and the molar ratio of ammonia and tetrapropoxysilane to hollow carbon is 0.1:1:
2. The mixture is stirred at room temperature.
6. The method for preparing a highly stable sandwich hollow structure hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material according to claim 1, characterized in that, The S5 has a silica-coated hollow carbon, iron salt, and hexamethylenetetramine mass ratio of 2:4 to 6:
1. The calcination temperature is 450℃, the heating rate from room temperature to 300℃ is 3℃ / min, the calcination time is 2 h, and the heating rate from 300℃ to 450℃ is 10℃ / min, the calcination time is 2 h.
7. The method for preparing a highly stable sandwich hollow structure hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material according to claim 1, characterized in that, The alkaline solution of S6 is 2 M NaOH, and the mass ratio of hollow carbon coated with iron oxide / silica to NaOH is 8:
1. The solution is stirred at 60°C until the color of the solution turns slightly gray.
8. The method for preparing a highly stable sandwich hollow structure hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material according to claim 1, characterized in that, The volume ratio of anhydrous ethanol to deionized water in S7 is 1:1, and the molar ratio of ammonia, tetrapropoxysilane, and hollow carbon coated with iron oxide is 0.1:1:
2. The mixture is stirred at room temperature. The volume ratio of the mixed solution E of S8 to tetrabutyl titanate is 10:1, the water bath temperature is 55℃, the water bath time is 24h, and the molar ratio of the hollow structure of silica-coated iron oxide-coated hollow structure to tetrabutyl titanate is 5:
1. The alkaline solution of S9 is 2 M NaOH, and the mass ratio of titanium dioxide-coated hollow silica / iron oxide-coated hollow carbon to NaOH is 8:
1. Stir at 60℃ until the solution turns slightly gray. The S10 is calcined at 450℃, with a heating rate of 5℃ / min, for 4 hours.
9. A highly stable sandwich hollow structure hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material, characterized in that, It is prepared by any one of claims 1-8.
10. An application of the highly stable sandwich hollow structure hydrogenated titanium dioxide / iron tetroxide / hollow carbon composite material as described in claim 9, characterized in that, Used to prepare anode materials for lithium-ion batteries.