A method for preparing a titanium niobium oxide low-temperature electrode material

Abstract

The application provides a method for preparing a titanium-niobium oxide low-temperature electrode material. The method is characterized in that the titanium-niobium oxide low-temperature electrode material is prepared by a co-precipitation method, potassium heptafluoroniobate is used as a niobium source, titanyl sulfate is used as a titanium source, and ammonia is used as a co-precipitation agent, and carbon nanotubes are used together. By changing the feeding ratio of the precursor, the calcination temperature and the calcination atmosphere, titanium-niobium oxide low-temperature electrode materials with different properties can be obtained. The preparation method is simple and safe, and the prepared titanium-niobium oxide low-temperature electrode material has high capacity performance as a negative electrode material of a lithium ion battery.

Description

Technical Field

[0001] This invention relates to a method for preparing a low-temperature electrode material of titanium niobium oxide used in lithium-ion battery anode materials, belonging to the field of functional materials technology. Background Technology

[0002] Lithium-ion batteries are widely used in portable electronic devices, communications, and many other fields due to their advantages such as high specific capacity, high voltage, low self-discharge, long cycle life, and wide operating temperature range. In recent years, the rapid development of the new energy vehicle industry has brought increasing attention to lithium-ion batteries, leading to higher demands on them. Traditional lithium-ion battery anode materials, such as graphite and lithium titanate, suffer from slow chemical kinetics and safety issues at high rates, making it difficult to meet the requirements of high energy and high power. Therefore, developing lithium-ion battery anode materials with high specific capacity, high power, and high safety has become a hot topic of concern.

[0003] Transition metal oxide anodes have attracted widespread attention from researchers due to their excellent rate performance, safety, abundant reserves, and affordable prices. Titanium and niobium are both transition metals, and their oxides are also transition metal oxides. Because titanium and niobium have similar atomic radii and chemical properties, their oxides can form a solid solution in a certain proportion, becoming titanium-niobium oxide (Ti-Nb-O). Titanium-niobium oxide is considered a highly promising anode material for lithium-ion batteries due to its high lithium storage capacity (theoretical specific capacity of around 390 mAh / g), structural stability, suitable lithium intercalation potential (around 1.6V), and good cycle performance. However, since both Ti and Nb are in their highest valence state (Ti... 4+ and Nb 5+ The 3d / 4d orbitals do not contain electrons, which makes the material have poor electrical conductivity. This is an important factor limiting its electrochemical performance. Therefore, it is necessary to improve the conductivity of the material and enhance its electrochemical performance through methods such as crystal structure modification and conductive phase composite.

[0004] Carbon nanotubes, due to their large specific surface area, small size, high mechanical strength, and high electrical conductivity, are often used as composite materials for electrode materials to enhance their electrochemical performance. Currently, there is much research on using titanium niobium oxide composites with carbon nanotubes as electrode materials, but most studies use tetrabutyl titanate and niobium pentachloride as the titanium and niobium sources, respectively. This invention uses titanium oxysulfate and potassium heptafluoroniobate as the titanium and niobium sources, respectively, and ammonia as a co-precipitant to synthesize a low-temperature titanium niobium oxide electrode material through chemical co-precipitation. Its cycle performance was then tested as a lithium-ion battery anode material. Summary of the Invention

[0005] The purpose of this invention is to provide a method for synthesizing titanium niobium oxide and its composite materials. This method uses titanium oxysulfate and potassium heptafluoroniobate as precursors, and synthesizes titanium niobium oxide low-temperature electrode materials through chemical co-precipitation with ammonia as the co-precipitant. This preparation method is simple, convenient to operate, and yields materials with excellent electrochemical performance.

[0006] This invention is implemented as follows: using titanium oxysulfate, potassium heptafluoroniobate, and carbon nanotubes as raw materials, a mixture containing Ti is prepared. 4+ 、Nb 5+ TiO2 / Nb2O5 low-temperature electrode powder was prepared by chemical co-precipitation using ammonia water as a precipitant, followed by precipitation, hydrothermal treatment, washing, drying, and calcination. The TiO2 / Nb2O5 low-temperature electrode powder was then placed in a tube furnace and calcined at high temperature under an argon atmosphere to obtain titanium niobium oxide low-temperature electrode powder.

[0007] The specific implementation steps are divided into four steps: (1) preparing aqueous solutions containing titanium and niobium respectively; (2) preparing TiO2 and Nb2O5 by co-precipitation and mixing them; (3) transferring the mixed solution to a reaction vessel to obtain TiO2 / Nb2O5 composite powder; (4) calcining the TiO2 / Nb2O5 composite powder at high temperature under an argon atmosphere to obtain titanium niobium oxide low-temperature electrode material. The four steps are described in detail below:

[0008] Prepare aqueous solutions containing titanium and niobium respectively.

[0009] Dissolve 0.005 mol TiOSO4 in 30 ml H2O to obtain Ti 4+ A solution was prepared, and 0.03 g of carbon nanotubes were dispersed into the solution by ultrasound. Additionally, K2NbF7 was weighed according to a molar ratio of TiOSO4:K2NbF7 of (1:1.6) to (1:2.8), and dissolved together with 0.5 g of PVP in 30 ml of H2O to obtain Nb. 5+ Prepare the solutions by stirring each solution separately for 30 minutes.

[0010] TiO2 and Nb2O5 were prepared by co-precipitation and then mixed.

[0011] Using ammonia as a co-precipitant, it was added dropwise to Ti. 4+ and Nb 5+ In both solutions, adjust the pH to ≥10 to form a suspension; after the addition is complete, stir for 1 hour, then add Nb. 5+ Solution added dropwise to Ti 4+ In the solution, the two are mixed and stirred for another 1 hour.

[0012] The mixed solution was transferred to a reaction vessel to obtain TiO2 / Nb2O5 low-temperature electrode powder.

[0013] The mixed solution was transferred to a reaction vessel and placed in an oven at 160°C to continue the reaction for 5 hours. After the reaction was completed, the mixture was allowed to cool naturally, filtered, washed, and dried to obtain TiO2 / Nb2O5 low-temperature electrode powder.

[0014] TiO2 / Nb2O5 low-temperature electrode powder was calcined at high temperature under an argon atmosphere to obtain titanium niobium oxide low-temperature electrode material.

[0015] TiO2 / Nb2O5 low-temperature electrode powder was placed in a tube furnace and heated from room temperature to 750–850°C at a rate of 10°C / min under an argon atmosphere. The powder was then calcined at this temperature for 3 hours and naturally cooled to obtain the final titanium niobium oxide low-temperature electrode material.

[0016] The method for synthesizing titanium niobium oxide low-temperature electrode materials provided by this invention is characterized by:

[0017] It is possible to synthesize low-temperature electrode materials of titanium niobium oxide containing different proportions of titanium and niobium;

[0018] The synthesized titanium niobium oxide low-temperature electrode material exhibits good electrochemical performance at both room temperature and low temperature;

[0019] The synthesis process is simple and easy to operate. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the process for preparing titanium niobium oxide low-temperature electrode materials according to the present invention.

[0021] Figure 2 The X-ray diffraction pattern of the titanium niobium oxide low-temperature electrode material prepared for the present invention.

[0022] Figure 3 These are scanning electron microscope images of the titanium niobium oxide low-temperature electrode materials prepared in Example 3 and Comparative Example 2 of the present invention.

[0023] Figure 4 The graph shows the room-temperature cycling performance test results of the titanium niobium oxide low-temperature electrode material prepared as an example of the present invention for lithium-ion batteries.

[0024] Figure 5 The image shows the low-temperature cycling performance test results of the titanium niobium oxide low-temperature electrode material prepared in Comparative Example 2 of this invention for lithium-ion batteries. Detailed Implementation

[0025] The testing method used in this invention is the LIR2025 button cell, mainly for negative electrode half-cell testing.

[0026] The prepared titanium niobium oxide electrode material, conductive agent SP and polyvinylidene fluoride PVDF were mixed in a mass ratio of 8:1:1, and a slurry was prepared using N-methylpyrrolidone (NMP) as a solvent. The slurry was coated on copper foil, dried in a vacuum drying oven, and then cut into electrode sheets with a diameter of 14 mm.

[0027] The test battery used was an LIR2025 coin cell, assembled in the following order: positive electrode casing, titanium niobium oxide electrode sheet, electrolyte, Celgard 2325 separator, lithium sheet, nickel foam, and negative electrode casing. The assembly process was carried out in a glove box where the volume fractions of water and oxygen were both below 0.01 ppm.

[0028] The lithium-ion battery prepared according to the present invention was tested using the following method:

[0029] 1. The cycle performance of the battery was tested using the Blue Battery Testing System at a working voltage of 1.0-3.0V and at room temperature, using a constant rate of 0.1C for 50 cycles.

[0030] 2. The cycle performance of the battery was tested using the Blue Battery Testing System at a working voltage of 1.0-3.0V and a constant rate of 0.1C for 20 cycles at -40℃.

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0032] The technical solution of a method for preparing titanium niobium oxide low-temperature electrode material is described below:

[0033] Example 1

[0034] Dissolve 0.8 g (0.005 mol) of TiOSO4 in 30 ml of H2O to obtain Ti 4+ A solution was prepared, and 0.03 g of carbon nanotubes were dispersed into the solution by ultrasound; additionally, 0.27 g of K₂NbF₇ and 0.5 g of PVP were dissolved together in 30 ml of H₂O to obtain Nb 5+ The two solutions were stirred separately for 30 minutes. Ammonia was added dropwise to both solutions as a co-precipitant, and the pH was adjusted to ≥10 to form a suspension. After the addition was complete, the solution was stirred for 1 hour. Then, Nb... 5+ Solution added dropwise to Ti 4+ In the solution, the two are mixed and stirred for another 1 hour.

[0035] The mixture was transferred to a reaction vessel, which was then placed in an oven at 160°C for 5 hours. After the reaction was complete, the mixture was allowed to cool naturally, filtered, washed, and dried to obtain TiO2 / Nb2O5 low-temperature electrode powder. This powder was then heated from room temperature to 750°C at a rate of 10°C / min under an argon atmosphere and calcined at this temperature for 3 hours. After natural cooling, TiO2 / Nb2O5 was finally obtained. 4+ :Nb 5+ A titanium-niobium oxide low-temperature electrode material with a ratio of 1:2.8 Figure 2 This is its X-ray diffraction pattern. As a lithium-ion battery anode material, its test results at room temperature are as follows... Figure 4 As shown, the first charge capacity at a room temperature and a 0.1C rate is 207.37mAh / g, and the coulombic efficiency is 83.74%.

[0036] Example 2

[0037] 0.8 g (0.005 mol) of TiOSO4 was dissolved in 30 ml of H2O to obtain a Ti4+ solution, and 0.03 g of carbon nanotubes were dispersed into this solution by sonication. Separately, 0.22 g of K2NbF7 and 0.5 g of PVP were dissolved together in 30 ml of H2O to obtain an Nb5+ solution. Both solutions were stirred for 30 min. Ammonia was used as a co-precipitant and added dropwise to the two solutions respectively to adjust the pH of the solution to ≥10 to form a suspension. After the addition was completed, the solution was stirred for 1 h. Then, the Nb5+ solution was added dropwise to the Ti4+ solution, and the two solutions were mixed and stirred for another 1 h.

[0038] The mixture was transferred to a reaction vessel, which was then placed in an oven at 160°C for 5 hours. After the reaction was complete, the mixture was allowed to cool naturally, filtered, washed, and dried to obtain TiO2 / Nb2O5 low-temperature electrode powder. This powder was then heated from room temperature to 750°C at a rate of 10°C / min under an argon atmosphere and calcined at this temperature for 3 hours. After natural cooling, a titanium niobium oxide low-temperature electrode material with a Ti4+:Nb5+ ratio of 1:2 was finally obtained. Figure 2 This is its X-ray diffraction pattern. As a lithium-ion battery anode material, its test results at room temperature are as follows... Figure 4 As shown, the first charge capacity at a room temperature and a 0.1C rate is 243.1mAh / g, and the coulombic efficiency is 93.2%.

[0039] Example 3

[0040] 0.8 g (0.005 mol) of TiOSO4 was dissolved in 30 ml of H2O to obtain a Ti4+ solution, and 0.03 g of carbon nanotubes were dispersed into this solution by sonication. Separately, 0.15 g of K2NbF7 and 0.5 g of PVP were dissolved together in 30 ml of H2O to obtain an Nb5+ solution. Both solutions were stirred for 30 min. Ammonia was used as a co-precipitant and added dropwise to the two solutions respectively to adjust the pH of the solution to ≥10 to form a suspension. After the addition was completed, the solution was stirred for 1 h. Then, the Nb5+ solution was added dropwise to the Ti4+ solution, and the two solutions were mixed and stirred for another 1 h.

[0041] The mixture was transferred to a reaction vessel, which was then placed in an oven at 160°C for 5 hours. After the reaction was complete, the mixture was allowed to cool naturally, filtered, washed, and dried to obtain TiO2 / Nb2O5 low-temperature electrode powder. This powder was then heated from room temperature to 750°C at a rate of 10°C / min under an argon atmosphere and calcined at this temperature for 3 hours. After natural cooling, a titanium niobium oxide low-temperature electrode material with a Ti4+:Nb5+ ratio of 1:1.6 was finally obtained. Figure 2 It is its X-ray diffraction pattern. Figure 3 (Left) shows a scanning electron microscope image of the material, indicating that its particle size is between 70-80 nm. As a potential anode material for lithium-ion batteries, its test results at room temperature are as follows... Figure 4 As shown, the first charge capacity at a room temperature and a 0.1C rate is 268.12mAh / g, and the coulombic efficiency is 87.55%.

[0042] Comparative Example 1

[0043] 0.8 g (0.005 mol) of TiOSO4 was dissolved in 30 ml of H2O to obtain a Ti4+ solution, and 0.03 g of carbon nanotubes were dispersed into this solution by sonication. Separately, 0.15 g of K2NbF7 and 0.5 g of PVP were dissolved together in 30 ml of H2O to obtain an Nb5+ solution. Both solutions were stirred for 30 min. Ammonia was used as a co-precipitant and added dropwise to the two solutions respectively to adjust the pH of the solution to ≥10 to form a suspension. After the addition was completed, the solution was stirred for 1 h. Then, the Nb5+ solution was added dropwise to the Ti4+ solution, and the two solutions were mixed and stirred for another 1 h.

[0044] The mixture was transferred to a reaction vessel, which was then placed in an oven at 160°C for 5 hours. After the reaction was complete, the mixture was allowed to cool naturally, filtered, washed, and dried to obtain TiO2 / Nb2O5 low-temperature electrode powder. This powder was then heated from room temperature to 800°C at a rate of 10°C / min under an argon atmosphere and calcined at this temperature for 3 hours. After natural cooling, a titanium niobium oxide low-temperature electrode material with a Ti4+:Nb5+ ratio of 1:1.6 was finally obtained. Figure 2This is its X-ray diffraction pattern. As a lithium-ion battery anode material, its test results at room temperature are as follows... Figure 4 As shown, the first charge capacity at a rate of 0.1C at room temperature is 281.19mAh / g, and the coulombic efficiency is 91.89%.

[0045] Comparative Example 2

[0046] 0.8 g (0.005 mol) of TiOSO4 was dissolved in 30 ml of H2O to obtain a Ti4+ solution, and 0.03 g of carbon nanotubes were dispersed into this solution by sonication. Separately, 0.15 g of K2NbF7 and 0.5 g of PVP were dissolved together in 30 ml of H2O to obtain an Nb5+ solution. Both solutions were stirred for 30 min. Ammonia was used as a co-precipitant and added dropwise to the two solutions respectively to adjust the pH of the solution to ≥10 to form a suspension. After the addition was completed, the solution was stirred for 1 h. Then, the Nb5+ solution was added dropwise to the Ti4+ solution, and the two solutions were mixed and stirred for another 1 h.

[0047] The mixture was transferred to a reaction vessel, which was then placed in an oven at 160°C for 5 hours. After the reaction was complete, the mixture was allowed to cool naturally, filtered, washed, and dried to obtain TiO2 / Nb2O5 low-temperature electrode powder. This powder was then heated from room temperature to 850°C at a rate of 10°C / min under an argon atmosphere and calcined at this temperature for 3 hours. After natural cooling, a titanium niobium oxide low-temperature electrode material with a Ti4+:Nb5+ ratio of 1:1.6 was finally obtained. Figure 2 It is its X-ray diffraction pattern. Figure 3 (Right) shows a scanning electron microscope image of the material, indicating that its particle size is between 50-60 nm. As a potential anode material for lithium-ion batteries, its test results at room temperature are as follows... Figure 4 As shown, the first charge capacity at a 0.1C rate at room temperature is 320mAh / g, and the coulombic efficiency is 89.3%. The test results at low temperatures are as follows... Figure 5 As shown, the material has a first-cycle charge specific capacity of 212.4 mAh / g and a discharge specific capacity of 245.6 mAh / g at -40℃ and a 0.1C rate, with a coulombic efficiency of 86.51%.

Claims

1. A method for producing a titanium niobium oxide low temperature electrode material, characterized by, The preparation method mainly comprises four steps: (1) TiOSO4 and K2NbF7 were weighed according to a molar ratio of 1:2 and dissolved in deionized water respectively to obtain Ti 4+ solution and Nb 5+ solution, 0.03 g carbon nanotubes were dispersed into Ti 4+ solution by ultrasonic method, 0.5 g PVP was dissolved into Nb 5+ solution; (2) Ammonia is used as the coprecipitation agent, which is added into Ti 4+ and Nb 5+ solutions respectively to form a suspension with pH≥10. After the addition is completed, the solution is stirred for 1 h. Then, the Nb 5+ solution is added into the Ti 4+ solution. After mixing, the solution is stirred for 1 h to obtain TiO2 and Nb2O5. (3) transferring the mixed solution into a reaction kettle to prepare TiO2 / Nb2O5 low-temperature electrode powder; (4) calcining the TiO2 / Nb2O5 low-temperature electrode powder under an argon atmosphere at high temperature to prepare a titanium-niobium oxide low-temperature electrode material.

2. The method for preparing the titanium niobium oxide low-temperature electrode material according to claim 1, characterized in that, In the step (3), the reaction kettle is placed in an oven to continue the reaction, and the reaction conditions are as follows: temperature 160 DEG C, time 5h; after the reaction is completed, filtration, washing and drying are carried out to obtain the TiO2 / Nb2O5 low-temperature electrode powder.

3. The method of claim 1, wherein the titanium niobium oxide low temperature electrode material is prepared by the steps of: preparing a solution of titanium and niobium salts; adding a reducing agent to the solution; and precipitating the titanium niobium oxide low temperature electrode material. In the step (4), the calcination process of the TiO2 / Nb2O5 low-temperature electrode powder is as follows: the temperature is increased from room temperature to 750-850 DEG C at a rate of 10 DEG C / min, and then the temperature is naturally cooled after being kept for 3h; finally, the titanium-niobium oxide low-temperature electrode material is obtained.

4. Use of the titanium-niobium oxide low temperature electrode material produced according to the production method according to any one of claims 1 to 3, characterized in that The titanium-niobium oxide low-temperature electrode material is assembled into a button cell as a lithium ion battery negative electrode material, and performance test is carried out.

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