Lithium titanate material with truncated octahedron shape and preparation method thereof
By adding MoO3 and organic carbon sources to the solid phase method to control the high-temperature sintering process, the synthesis of Li4Ti5O12 material with cut-top octahedral morphology was achieved, solving the problem of uneven morphological control, improving the electrochemical performance of the material and reducing production costs.
Patent Information
- Application Number
- CN202510539851.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-27
- Publication Date
- 2025-08-08
AI Technical Summary
It is difficult to prepare Li4Ti5O12 material with a octahedral shape in the existing solid phase method, which has problems such as uneven morphological control, kinetic limitations and high temperature conditions, making it difficult to achieve nanostructures.
By adding MoO3 and organic carbon sources to the solid phase method, controlling the high-temperature sintering process, generating MoO2 in situ, and controlling the {111} and {100} crystal plane energy of Li4Ti5O12 material, the synthesis of the octahedral morphology is achieved.
The octahedral lithium titanate material with uniform dispersion and uniform particle size was successfully prepared, which improved the electrochemical performance of the material, reduced costs and was suitable for large-scale production.
Smart Images
Figure CN120440942A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a lithium titanate material with a truncated octahedron shape and a preparation method thereof, belonging to the technical field of electrode materials. Background Art
[0002] Li4Ti5O 12 showed about 1.55V (vs. Li / Li + ) stable charge and discharge voltage. This characteristic effectively inhibits the formation of the solid electrolyte interface (SEI) layer and the growth of lithium dendrites, significantly improving the material's safety. Furthermore, the material has a theoretical specific capacity of 175 mAh / g, and its crystal structure remains virtually unchanged during charge and discharge cycles, earning it the nickname "zero strain" material.
[0003] By regulating the morphology, the performance and function of the material can be improved, and the Li4Ti5O 12 The main methods for material synthesis include sol-gel method, molten salt method and hydrothermal method, but few methods use solid phase method to control Li4Ti5O 12 Material morphology. The solid-phase method can precisely control the composition and structure of the material, and the structure of the material synthesized by the solid-phase method is stable, the process is simple and suitable for large-scale production. However, the solid-phase method has disadvantages such as kinetic limitations, long reaction time, difficulty in achieving nanostructures, high temperature conditions and difficulty in achieving uniform morphology. In contrast, wet chemical methods such as solution method and hydrothermal method may be more conducive to achieving fine morphology control. At present, no solid-phase method has been used to prepare Li4Ti5O with truncated octahedron or similar morphology. 12 . Summary of the Invention
[0004] In order to overcome the problems in the background technology, the present invention provides a lithium titanate material having a truncated octahedron shape and a preparation method thereof.
[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions:
[0006] A method for preparing a lithium titanate material having a truncated octahedron shape comprises the following steps:
[0007] (1) mixing a titanium source compound, a lithium source compound, and MoO3 to obtain a precursor mixture;
[0008] (2) Adding an organic carbon source to the precursor mixture and mixing evenly, then sintering at high temperature and cooling naturally to obtain Li4Ti5O 12 Material.
[0009] Preferably, the lithium source compound, titanium source compound and MoO3 are Li4Ti 5-x Mo xO4, x<0.4, mixing is performed.
[0010] Preferably, the precursor mixture and the organic carbon source are mixed by ball milling, the ball milling speed is 200-600 rpm, the time is 2-6 hours, and the ball milling medium is zirconia balls.
[0011] Preferably, the mass ratio of the organic carbon source to the precursor mixture is 0.03-0.1:1.
[0012] Preferably, the high-temperature sintering atmosphere is argon, the heating rate is 2-10°C / min, the temperature is first raised to 300-500°C, kept warm for 0.5-10h, then raised to 750-800°C, kept warm for 5-12h.
[0013] The present invention also claims a method for preparing a lithium titanate material having a truncated octahedron shape. The prepared lithium titanate material having a truncated octahedron shape has a chemical formula of Li4Ti 5-x Mo x O4, x<0.4, where Mo is tetravalent.
[0014] The beneficial effects of the present invention are as follows: the present invention utilizes the simple operation characteristics of the solid phase method, and controls the addition of a small amount of additive MoO3 and an organic carbon source to in situ generate MoO2, and tetravalent molybdenum enters the lattice to reduce the {111} and {100} crystal plane energy, thereby realizing the one-step solid phase method to synthesize Mo with exposed {111} and {100} truncated octahedrons. 4+ Doped Li4Ti5O 12 Therefore, the present invention can achieve the purpose of regulating Li4Ti5O by adding MoO3 and organic carbon source. 12 Morphological preparation of Mo with exposed {111} and {100} truncated octahedrons 4+ Doped Li4Ti5O 12 The purpose is to utilize its unique morphology and doped ions to improve the electrochemical performance of the material. A lithium titanate material with a relatively uniform dispersion of octahedral morphology and uniform particle size is synthesized. The preparation method of the present invention avoids the oxidation of divalent molybdenum to a higher valence state during ball milling caused by the direct addition of molybdenum dioxide, and avoids the interference of molybdenum in other valence states that can lead to uneven morphology control. The synthesis method is simple to operate, low in cost, and has the potential for large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 The product Li4Ti5O synthesized in Example 1 12 Comparative Example 1 product XRD spectrum.
[0016] Figure 2The SEM images of the materials prepared in Example 1 and Comparative Example 1 are shown in Figure 1. (a) is the product Li4Ti5O synthesized in Example 1. 12 (b) is the SEM image of the product of Comparative Example 1.
[0017] Figure 3 1 and 2 are performance comparison diagrams of the materials prepared in Example 1 and Comparative Example 1, (a) is the Nyquist curve diagram of the materials prepared in Example 1 and Comparative Example 1, and (b) is the relationship between Zw and x-1 / 2 in the low-frequency region of the electrode of the materials prepared in Example 1 and Comparative Example 1.
[0018] Figure 4 The product Li4Ti5O synthesized in Example 1 12 Capacity diagram at different rates compared with the product of Comparative Example 1.
[0019] Figure 5 This is the SEM image of the material prepared in Comparative Example 2.
[0020] Figure 6 This is the SEM image of the material prepared in Comparative Example 3. DETAILED DESCRIPTION
[0021] The present invention will be further described in detail below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.
[0022] Example 1
[0023] A method for preparing a lithium titanate material having a truncated octahedron shape comprises the following steps:
[0024] (1) Li2CO3, TiO2, and MoO3 were weighed and mixed in a molar ratio of 2:4.97:0.03 to obtain a precursor mixture; citric acid was added to the precursor mixture, and the mixture was mixed by ball milling at a speed of 400 rpm for 4 hours using zirconium oxide balls. The mass ratio of the citric acid to the precursor mixture was 5.0 wt%, and the mixture was then transferred to a crucible.
[0025] (2) Place the crucible in a muffle furnace, heat it to 450°C at a rate of 3°C / min, keep it warm for 3 h, then heat it to 800°C and keep it warm for 10 h.
[0026] (3) After cooling to room temperature, the target product is obtained.
[0027] Example 2
[0028] A method for preparing a lithium titanate material having a truncated octahedron shape comprises the following steps:
[0029] (1) Li2CO3, TiO2, and MoO3 were weighed and mixed in a molar ratio of 2:4.985:0.015 to obtain a precursor mixture; the mixture was ball-milled in the precursor mixture at a speed of 200 rpm for 6 hours using zirconium oxide balls. The mass ratio of sucrose to the precursor mixture was 0.03:1, and the mixture was then transferred to a crucible.
[0030] (2) Place the crucible in a muffle furnace, heat it to 500°C at a rate of 2°C / min, keep it warm for 0.5 h, then heat it to 750°C and keep it warm for 12 h.
[0031] (3) After cooling to room temperature, the target product is obtained.
[0032] Example 3
[0033] A method for preparing a lithium titanate material having a truncated octahedron shape comprises the following steps:
[0034] (1) Li2CO3, TiO2, and MoO3 were weighed and mixed in a molar ratio of 2:4.955:0.035 to obtain a precursor mixture; a mixture of citric acid and sucrose was added to the precursor mixture, and the mixture was mixed by ball milling to obtain a precursor mixture; the ball milling speed was 600 rpm, the time was 2 hours, and the ball milling medium was zirconia balls. The mass ratio of the citric acid and sucrose mixture to the precursor mixture was equal to 0.1:1, and then the mixture was transferred to a crucible.
[0035] (2) After mixing evenly, transfer the mixture into a crucible, place the crucible into a tube furnace, and heat it to 300°C at a rate of 10°C / min in an Ar atmosphere, keep it warm for 10 h, and then heat it to 800°C and keep it warm for 5 h.
[0036] (3) After cooling to room temperature, the target product is obtained.
[0037] Comparative Example 1
[0038] A method for preparing a lithium titanate material comprises the following steps:
[0039] (1) Li2CO3 and TiO2 were weighed in a molar ratio of 2:5 and mixed by ball milling to obtain a precursor mixture; the ball milling speed was 200-500 rpm, the time was 0.5-5 h, and the ball milling medium was zirconia balls.
[0040] (2) The precursor mixture was transferred into a crucible, and the crucible was placed in a tube furnace. The temperature was first raised to 450°C at a rate of 3°C / min under an Ar atmosphere, and the temperature was kept at 800°C and sintered for 10 hours.
[0041] (3) After cooling to room temperature, the target product is obtained.
[0042] Example 1: The product Li4Ti5O was synthesized by modified MoO3 solid phase method. 12 Compared with the XRD pattern of the product in Example 1, the first charge-discharge curve at 0.2C rate and the capacity at different rates are shown in FIG. Figure 1 、 Figure 2 and Figure 3 It can be seen that the materials synthesized by the products of Example 1 and Comparative Example 1 are pure phase Li4Ti5O 12 No impurity phase was observed.
[0043] according to Figure 2 (a) It can be seen that the product Li4Ti5O synthesized in Example 1 12 The particle size is 200-400nm, and the material has a truncated octahedral structure. Figure 2 (b) It can be seen that the particle size of the material prepared in Comparative Example 1 is about 200-400 nm, but the primary particles have irregular morphology and there is adhesion between the particles.
[0044] according to Figure 3 and 4 It can be seen that the interface impedance of the material synthesized in Example 1 is reduced, and the specific capacity is significantly better than that of the material in Comparative Example 1 at a high rate.
[0045] Comparative Example 2
[0046] A method for preparing a lithium titanate material comprises the following steps:
[0047] (1) Li2CO3, TiO2, and MoO3 were weighed in a molar ratio of 2:4.97:0.03 and mixed by ball milling to obtain a precursor mixture; the ball milling speed was 200-500 rpm, the time was 0.5-5 h, and the ball milling medium was zirconia balls.
[0048] (2) The precursor mixture was transferred into a crucible, and the crucible was placed in a tube furnace. The temperature was first raised to 450°C at a rate of 3°C / min under an Ar atmosphere, and the temperature was kept at 800°C and sintered for 10 hours.
[0049] (3) After cooling to room temperature, the target product is obtained.
[0050] Comparative Example 2 prepared Li4Ti 4.97 Mo 0.03 O 12 The material has a valence of +6 and the primary particle morphology is irregularly adhered particles. Using MoO3 alone cannot form an octahedral lithium titanate material.
[0051] Comparative Example 3
[0052] A method for preparing a lithium titanate material comprises the following steps:
[0053] (1) Li2CO3, TiO2, and MoO2 were weighed in a molar ratio of 2:4.97:0.03 and mixed by ball milling to obtain a precursor mixture; the ball milling speed was 200-500 rpm, the time was 0.5-5 h, and the ball milling medium was zirconia balls.
[0054] (2) The precursor mixture was transferred into a crucible, and the crucible was placed in a muffle furnace. The temperature was first raised to 450°C at a rate of 3°C / min, and the temperature was kept at this temperature for 3 h. The temperature was then raised to 800°C and the temperature was kept at this temperature for 10 h.
[0055] (3) After cooling to room temperature, the target product is obtained.
[0056] Comparative Example 3 prepared Li4Ti 4.97 Mo 0.03 O 12 The material has a valence state of Mo of +6 and +4 mixed, and the primary particle morphology is irregularly adhered particles.
[0057] In this comparative example, due to the high energy collision induced defects during the ball milling process, the impact energy generated by the collision between the ball milling medium and the powder causes oxygen vacancies to form in the MoO2 lattice, and the highly active Mo is generated simultaneously. 3+ The intermediate is more susceptible to oxidation by residual oxygen. Furthermore, frictional heat accumulates locally. Although the sintering temperature is lower than that of conventional sintering, the continued mechanical action reduces the activation energy for the formation of high-valent Mo oxides. XRD shows that ball milling of MoO2 generates a higher-valent MoO3 phase, and this higher-valent Mo oxide hinders the formation of octahedral lithium titanate.
[0058] Effect Example 1
[0059] 1.1 Preparation of negative electrode sheet
[0060] The materials prepared in the examples and comparative examples, conductive carbon black (Super P) and binder (PVDF) were weighed in a mass ratio of 9:0.5:0.5 and placed in an agate mortar to submerge and mix evenly. An appropriate amount of NMP (N-methylpyrrolidone) was added as a dispersant using a dropper and mixed thoroughly until the slurry had an appropriate viscosity. The slurry was evenly coated on aluminum foil using a coater and vacuum-dried in a vacuum oven at 80°C for 12 hours. The slurry was evenly coated on aluminum foil using a coater and vacuum-dried in a vacuum oven at 80°C for 12 hours. Then, circular electrodes were punched out.
[0061] 1.2 Assembling button batteries
[0062] The positive and negative battery shells, separators, nickel mesh and negative electrode sheets were dried for 2 hours and then transferred to a glove box with a high-purity argon atmosphere. The battery shell model used was CR2025, the negative electrode material was a thin sheet with a diameter of 14mm, the counter electrode used was a high-purity lithium sheet, and the electrolyte was a mixed solution of 1mol / L LiPF6 and an organic mixture of EC, DMC, and EMC in a volume ratio of 1:1:1. Two drops of electrolyte were added to the middle of the negative electrode shell, and then Li4Ti5O 12 Place the negative electrode sheet in the middle of the negative electrode shell with the coating facing up, and then add two drops of electrolyte to fully soak it. Place the polypropylene microporous diaphragm on top of the negative electrode sheet, ensuring that no bubbles appear, and then add one drop of electrolyte. Then place the lithium sheet, nickel foam, and positive electrode shell in order, and make sure that the negative electrode sheet and lithium sheet are aligned in the middle of the button battery. After the assembled button battery is taken out, seal it in a sealing machine at 50kg / cm 2 Seal under pressure.
[0063] Examples 2 and 3 have similar effects to Example 1, and lithium titanate with a truncated octahedral morphology can be synthesized. Moreover, the capacity is improved compared with the rate capacity of the unmodified lithium titanate prepared in Comparative Example 1.
[0064] The rate capacity of comparative examples 2-3 also decreased significantly compared to that of example 1, mainly because the lithium titanate material with octahedral morphology could not be formed ( Figure 5-6 ), and the valence state of Mo is not tetravalent, which leads to a larger interface impedance of the material and a significant decrease in rate capacity at high rates.
[0065] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.
Claims
1. A method for preparing a lithium titanate material having a truncated octahedron shape, characterized in that: The steps include: (1) mixing a titanium source compound, a lithium source compound, and MoO3 to obtain a precursor mixture, and adding an organic carbon source to the precursor mixture and mixing them uniformly; (2) Then, high temperature sintering is performed and naturally cooled to obtain Li4Ti5O 12 Material.
2. The method for preparing the lithium titanate material having a truncated octahedron shape according to claim 1, characterized in that: In the step (1), the lithium source compound, the titanium source compound and MoO3 are mixed according to Li4Ti 5-x Mo x O4, x<0.4, mixing is performed.
3. The method for preparing the lithium titanate material having a truncated octahedron shape according to claim 1, characterized in that: The precursor mixture and the organic carbon source are mixed by ball milling. The ball milling speed is 200-600 rpm, the time is 2-6 hours, and the ball milling medium is zirconia balls.
4. The method for preparing the lithium titanate material having a truncated octahedron shape according to claim 3, characterized in that: The mass ratio of the organic carbon source to the precursor mixture is 0.03-0.1:
1.
5. The method for preparing the lithium titanate material having a truncated octahedron shape according to claim 1, wherein: The high-temperature sintering atmosphere is argon, and the heating rate is 2-10°C / min. The temperature is first raised to 300-500°C, kept warm for 0.5-10 hours, and then raised to 750-800°C, kept warm for 5-12 hours. 6 . The lithium titanate material having a truncated octahedron shape prepared according to the method for preparing a lithium titanate material having a truncated octahedron shape according to claim 1 .
7. The lithium titanate material having a truncated octahedron shape according to claim 6, characterized in that: The chemical formula is Li4Ti 5-x Mo x O4, x<0.4, where Mo is tetravalent.