A bimetallic Mo2Ti2C3T x -based hybrid anode material, its preparation method and application
The preparation of bimetallic Mo2Ti2C3Tx hybrids by hydrofluoric acid pre-etching and hydrothermal method solves the problem of insufficient capacity and performance of the negative electrode materials of lithium-ion batteries in the prior art, and achieves efficient improvement of lithium storage performance.
Patent Information
- Application Number
- CN202410002474.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-02
- Publication Date
- 2025-07-25
- Estimated Expiration
- 2044-01-02
AI Technical Summary
The theoretical lithium storage capacity of graphite, the negative electrode material of the existing lithium-ion battery, is low in lithium storage capacity and poor in magnification performance, which cannot meet the needs of high power density and fast charging. Moreover, the preparation method of bimetallic MXenes is cumbersome and time-consuming, and the electrode material does not have obvious advantages in lithium storage capacity, cycle life and rate performance.
Bimetallic Mo2Ti2C3Tx hybrids were prepared at lower temperatures by hydrofluoric acid preetching combined with hydrothermal method. TixOy/MoxSy transition metal compounds were constructed in situ on the surface of MXenes nanosheets to enrich the lithium storage site and improve the conductivity.
The prepared bimetallic Mo2Ti2C3Tx hybrid exhibits excellent lithium storage performance, improves the specific capacity and cycle stability of the material, and synergizes with the conductive advantages of MXenes.
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Figure CN118016883B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of negative electrode materials for secondary batteries, and particularly to a bimetallic MXenes (Mo2Ti2C3T x )-based hybrid negative electrode material, a preparation method thereof, and an application thereof. Background Art
[0002] Portable electronic devices, electric vehicles, etc. have greatly enriched the material life of human beings. However, graphite, the negative electrode material most widely used in current commercial lithium-ion batteries, has a low theoretical lithium storage capacity (372 mAh / g) and relatively poor rate performance, etc., which can no longer meet people's requirements for secondary batteries with high power density, high energy density, fast charging, etc. Therefore, many researchers at home and abroad have carried out a lot of work, starting from different angles and different systems, to design and develop new lithium-ion battery negative electrode materials.
[0003] In 2011, Professor Yury Gogotsi of Drexel University in the United States and others first reported a new type of two-dimensional transition metal carbides and / or nitrides - MXenes (general formula: M n+1 X n T x ; n = 1 - 4; M = Ti, Nb, Mo, V, Zr......; X = C, N; Tx = -O, -OH, -F, -Cl......). Since then, due to the metallic conductivity, rich and controllable surface chemistry and phase structure, adjustable layer spacing and other excellent physical and chemical properties, it has attracted extensive research attention as an energy storage electrode. However, many works of many researchers have focused on single-metal MXenes (such as Ti3C2T x , Nb2CT x , Mo2CT x ......), and there is relatively little research on bimetallic MXenes materials with greater etching difficulty. The binary metal composition at the M position of bimetallic MXenes endows them with richer structures and physical and chemical properties, making them potential candidates for energy storage materials. The electrical properties and electrochemical behaviors of bimetallic MXenes nanosheets still need to be explored.
[0004] At present, the preparation methods for single-metal MXenes are relatively mature and perfect. For the preparation of bimetallic MXenes with more atomic layers, the etching of MXenes and subsequent intercalation and exfoliation are still relatively cumbersome and time-consuming. Most importantly, compared with other currently reported single-metal MXenes-based electrode materials, the prepared bimetallic MXenes electrode materials still do not have obvious advantages in terms of lithium storage specific capacity, cycle life, rate performance, etc. Summary of the Invention
[0005] Taking the 413 MAX phase - Mo2Ti2AlC3 as an example, the present invention demonstrates a strategy for preparing bimetallic MXenes hybrids by using acid treatment for pre - etching combined with subsequent hydrothermal methods and other processes. Under a relatively low reaction temperature (<300 °C) and a sulfur - containing vapor atmosphere, the pre - etched multi - layer Mo2Ti2C3T x is subjected to secondary microstructure modification of MXenes to further exfoliate it into few - layer MXenes, and in the case of not requiring additional addition of metal salts of transition metal elements, Ti x O y / Mo x S y transition metal compounds are in - situ constructed on the surface of MXenes nanosheets. The prepared bimetallic Mo2Ti2C3T x hybrids exhibit excellent lithium - storage performance.
[0006] To achieve the above - mentioned purpose, the technical solution adopted by the present invention is as follows:
[0007] A preparation method of a bimetallic Mo2Ti2C3T x - based hybrid anode material, comprising the following steps:
[0008] (1) Pre - etching the bimetallic MAX phase Mo2Ti2AlC3 with hydrofluoric acid to prepare multi - layer Mo2Ti2C3T x MXenes;
[0009] (2) Adopting the hydrothermal method and adding a sulfur source to perform secondary etching on the multi - layer Mo2Ti2C3T x MXenes to obtain bimetallic Mo2Ti2C3T x - based hybrids.
[0010] Furthermore, in the step (1), the method of pre - etching with hydrofluoric acid is as follows: the addition amount of the bimetallic MAX phase Mo2Ti2AlC3 is 0.5 g - 3 g, the addition amount of hydrofluoric acid is 15 mL - 30 mL, the pre - etching time is 48 h - 120 h, and the pre - etching temperature is 45 - 65 °C. Due to the differences in the addition amounts of MAX phase and hydrofluoric acid and the etching time, the morphologies and yields of the prepared multi - layer Mo2Ti2C3T x MXenes will be different.
[0011] Furthermore, in the step (2), the method of performing secondary etching on the multi - layer Mo2Ti2C3T x MXenes by the hydrothermal method is as follows: add the multi - layer Mo2Ti2C3T prepared by pre - etching into the inner lining of the hydrothermal reaction kettle xMXenes and sulfur source were reacted at a reaction temperature of 150 ℃ - 250 ℃ for 5 - 48 h to obtain bimetallic Mo2Ti2C3T x Hybrid.
[0012] Furthermore, the multilayer Mo2Ti2C3T x The mass ratio of MXenes to sulfur source (sulfur source precursor) is 1-9:10.
[0013] Furthermore, the sulfur source is one of thiourea, thioacetamide and sodium sulfide.
[0014] A bimetallic Mo2Ti2C3T prepared by the above preparation method x Based hybrid anode materials are used in lithium-ion batteries.
[0015] Compared with the prior art, the present invention has the following beneficial effects:
[0016] The present invention uses acid treatment pre-etching combined with subsequent hydrothermal method to prepare bimetallic MXenes hybrids. The prepared bimetallic Mo2Ti2C3T x Based hybrids, metal compounds (Mo x S y / Ti x O y ) - Support (Mo2Ti2C3T x The strong interaction between MXenes effectively enriches the lithium storage sites of the hybrid material, while synergistically inheriting and exerting the excellent conductivity of MXenes, further improving the lithium storage capacity of the hybrid material. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 The bimetallic Mo2Ti2C3T x Transmission electron microscopy image of hybrid negative electrode material, where the particles on the surface of the nanosheet are in-situ grown Ti x O y / Mo x S y etc. transition metal compounds, as marked in the yellow dotted circle;
[0018] Figure 2 The present invention is pre-etched to prepare multi-layer Mo2Ti2C3T x Scanning electron microscope image of MXenes;
[0019] Figure 3 The present invention is pre-etched to prepare multi-layer Mo2Ti2C3T x MXenes and Mo2Ti2C3T xComparison chart of cyclic performance curves of the base hybrid anode material. Detailed implementation mode
[0020] The technical solutions and effects of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto. Example 1
[0021] A preparation method of a bimetallic MXenes (Mo2Ti2C3T x ) based hybrid anode material, comprising the following steps:
[0022] (1) Prepare multilayer Mo2Ti2C3T x MXenes by pre-etching Mo2Ti2AlC3 MAX phase with hydrofluoric acid;
[0023] Prepare multilayer Mo2Ti2C3T x MXenes by liquid-phase etching method, and the specific method is as follows:
[0024] Use Mo2Ti2AlC3 as the MXenes precursor and 49 wt% hydrofluoric acid as the etchant. First, place a polytetrafluoroethylene beaker with holes drilled at the edge of the cup wall in a water bath, and then use a pipette to measure 15 mL of hydrofluoric acid and transfer it into the polytetrafluoroethylene beaker; weigh 2 g of Mo2Ti2AlC3 powder with a precision electronic balance, and then slowly add it to the hydrofluoric acid solution in small amounts and multiple times; cover the beaker lid after adding, and start constant-temperature water bath stirring; after the pre-etching is completed, use deionized water and centrifuge at high speed until the supernatant is neutral. The water bath temperature is set at 55 °C, the pre-etching time is 96 h, and the stirring speed is set at 900 r / min. The scanning electron microscope image of the pre-etched multilayer Mo2Ti2C3T x MXenes is as Figure 2 shown.
[0025] (2) Use the hydrothermal method to perform secondary etching on multilayer Mo2Ti2C3T x MXenes, and the specific method is as follows:
[0026] Use the aqueous solution of multilayer Mo2Ti2C3T x MXenes as the precursor and thioacetamide as the sulfur source; take 30 mL of Mo2Ti2C3T xAn aqueous solution of MXenes (with a concentration of 1 mg / mL to 10 mg / mL) is placed in a beaker, and thioacetamide (0.01 g to 0.1 g) is added. The mass ratio of multi-layer MXenes to the sulfur source precursor is 1:10, and the mixture is stirred for 30 min. The uniformly mixed solution is transferred into a polytetrafluoroethylene liner, and hydrothermal reaction is carried out at 200 °C for 24 h. After the reaction ends, it is naturally cooled to room temperature, and the solid-liquid mixture after the reaction is taken out and centrifuged and washed 3 to 5 times, and then freeze-dried to obtain the Mo2Ti2C3T x -based hybrid anode material. The bimetallic Mo2Ti2C3T x -based hybrid anode material's transmission electron microscope image is as Figure 1 shown. The particles on the surface of the nanosheets are in-situ grown Ti x O y / Mo x S y and other transition metal compounds, as marked in the yellow dotted circle.
[0027] The Mo2Ti2C3T x -based hybrid anode material prepared in this example, activated carbon, PVDF, etc. are pre-mixed evenly in a mortar at a mass ratio of 80:10:10, and then NMP is added and ground to prepare a slurry with a certain viscosity. It is uniformly coated on the copper foil using a scraper, and finally dried in vacuum at 100 °C for 12 h. After cooling to room temperature, the sample is cut into pieces to assemble a battery to test the electrochemical performance of the material. Example 2
[0028] A preparation method of a bimetallic MXenes (Mo2Ti2C3T x )-based hybrid anode material, comprising the following steps:
[0029] (1) Pre-etch the Mo2Ti2AlC3 MAX phase with hydrofluoric acid to prepare multi-layer Mo2Ti2C3T x MXenes;
[0030] Prepare multi-layer Mo2Ti2C3T x MXenes by liquid-phase etching method. The specific method is as follows:
[0031] Using Mo2Ti2AlC3 as the MXenes precursor and 49 wt% hydrofluoric acid as the etching agent. First, place a polytetrafluoroethylene beaker with holes drilled at the edge of the cup wall in a water bath, then use a pipette to measure 15 mL of hydrofluoric acid and transfer it into the polytetrafluoroethylene beaker; weigh 2 g of Mo2Ti2AlC3 powder using a precision electronic balance, and then slowly add it to the hydrofluoric acid solution in small portions; after adding, cover the beaker lid and start the constant temperature water bath stirring; after the pre-etching is completed, use deionized water and centrifuge at high speed until the supernatant is neutral. The water bath temperature is set at 65 °C, the pre-etching time is 48 h, and the stirring speed is set at 900 r / min.
[0032] (2)Hydrothermally treat the multi-layer Mo2Ti2C3T x for secondary etching of MXenes, and the specific method is as follows:
[0033] Use the multi-layer Mo2Ti2C3T x MXenes aqueous solution as the precursor and thioacetamide as the sulfur source; take 30 mL of Mo2Ti2C3T x MXenes aqueous solution (with a concentration of 1 mg / mL to 10 mg / mL) and place it in a beaker, add thioacetamide (0.01 g to 0.1 g), and the mass ratio of the multi-layer MXenes to the sulfur source precursor is 3:10, stir and mix for 30 min; transfer the uniformly mixed solution into a polytetrafluoroethylene inner liner, and perform a hydrothermal reaction at 150 °C for 48 h. After the reaction, naturally cool to room temperature, take out the solid-liquid mixture after the reaction and centrifuge and wash it 3 to 5 times, and freeze-dry to obtain the Mo2Ti2C3T x -based hybrid anode material.
[0034] The Mo2Ti2C3T x -based hybrid anode material prepared in this example, activated carbon, PVDF, etc. are pre-mixed evenly in a mortar at a mass ratio of 80:10:10, then add NMP and grind to prepare a slurry with a certain viscosity, use a spatula to evenly coat it on the copper foil, and finally dry it in vacuum at 100 °C for 12 h. After cooling to room temperature, cut the sheet and assemble the battery to test the electrochemical performance of the material. Example 3
[0035] A preparation method of a bimetallic MXenes (Mo2Ti2C3T x )-based hybrid anode material, comprising the following steps:
[0036] (1)Prepare multi-layer Mo2Ti2C3T x MXenes by pre-etching Mo2Ti2AlC3 MAX phase with hydrofluoric acid;
[0037] Preparation of multi-layer Mo2Ti2C3T x MXenes by liquid-phase etching method, and the specific method is as follows:
[0038] Using Mo2Ti2AlC3 as the MXenes precursor and 49 wt% hydrofluoric acid as the etching agent. First, place a polytetrafluoroethylene beaker with holes drilled at the edge of the cup wall in a water bath, and then use a pipette to measure 15 mL of hydrofluoric acid and transfer it into the polytetrafluoroethylene beaker; weigh 2 g of Mo2Ti2AlC3 powder using a precision electronic balance, and then add it slowly to the hydrofluoric acid solution in small amounts and multiple times; cover the beaker lid after adding, and start the constant-temperature water bath stirring; after the pre-etching is completed, use deionized water and centrifuge at high speed until the supernatant is neutral. The water bath temperature is set at 45 °C, the pre-etching time is 120 h, and the stirring speed is set at 900 r / min.
[0039] (2)Use the hydrothermal method to perform secondary etching on multi-layer Mo2Ti2C3T x MXenes, and the specific method is as follows:
[0040] Using the aqueous solution of multi-layer Mo2Ti2C3T x MXenes as the precursor and thioacetamide as the sulfur source; take 30 mL of Mo2Ti2C3T x MXenes aqueous solution (concentration 1 mg / mL - 10 mg / mL) and place it in a beaker, add thioacetamide (0.01 g - 0.1 g), and the mass ratio of multi-layer MXenes to the sulfur source precursor is 5:10. Stir and mix for 30 min; transfer the uniformly mixed solution into a polytetrafluoroethylene inner liner and perform a hydrothermal reaction at 250 °C for 10 h. After the reaction, naturally cool to room temperature, take out the solid-liquid mixture after the reaction and centrifuge and wash it 3 - 5 times, and freeze-dry to obtain the Mo2Ti2C3T x -based hybrid anode material.
[0041] Pre-mix the Mo2Ti2C3T x -based hybrid anode material, activated carbon, PVDF, etc. prepared in this example in a mortar in a mass ratio of 80:10:10, then add NMP and grind to prepare a slurry with a certain viscosity, use a spatula to evenly coat it on the copper foil, and finally dry it in vacuum at 100 °C for 12 h. After cooling to room temperature, cut the sheet and assemble the battery to test the electrochemical performance of the material. Example 4
[0042] A preparation method of a bimetallic MXenes (Mo2Ti2C3T x )-based hybrid anode material, comprising the following steps:
[0043] (1) The Mo2Ti2AlC3MAX phase was pre-etched by hydrofluoric acid to prepare multilayer Mo2Ti2C3T x MXenes;
[0044] Preparation of multilayer Mo2Ti2C3T by liquid phase etching x MXenes, the specific method is as follows:
[0045] Using Mo2Ti2AlC3 as the MXenes precursor and 49 wt% hydrofluoric acid as the etchant, first, place a polytetrafluoroethylene beaker with holes drilled on the edge of the cup wall in a water bath, then use a pipette to measure 15 mL of hydrofluoric acid and transfer it into the polytetrafluoroethylene beaker; use a precision electronic balance to weigh 2 g of Mo2Ti2AlC3 powder, and then slowly add it to the hydrofluoric acid solution in small amounts and multiple times; cover the beaker lid after adding, open the constant temperature water bath for stirring; use deionized water after pre-etching, and wash at high speed until the supernatant is neutral. The water bath temperature is set to 50 ℃, the pre-etching time is 96 h, and the stirring speed is set to 900 r / min.
[0046] (2) Multilayer Mo2Ti2C3T was prepared by hydrothermal method x MXenes secondary etching, the specific method is as follows:
[0047] Using multi-layer Mo2Ti2C3T x MXenes aqueous solution was used as a precursor, and thioacetamide was used as a sulfur source. 30 mLMo2Ti2C3T x MXenes aqueous solution (concentration of 1 mg / mL ~ 10 mg / mL) was placed in a beaker, thioacetamide (0.01g ~ 0.1 g) was added, and the mass ratio of multilayer MXenes to sulfur source precursor was 7:10, and stirred for 30 min; the mixed solution was transferred into a polytetrafluoroethylene liner and hydrothermally reacted at 250 °C for 5 h. After the reaction was completed, it was naturally cooled to room temperature, and the solid-liquid mixture after the reaction was taken out and centrifuged for 3 to 5 times, and freeze-dried to obtain Mo2Ti2C3T x Based hybrid negative electrode materials.
[0048] The Mo2Ti2C3T prepared in this example x The hybrid negative electrode material, activated carbon, PVDF, etc. were pre-mixed in a mortar at a mass ratio of 80:10:10, and then NMP was added to grind to prepare a slurry with a certain viscosity, which was evenly coated on the copper foil with a scraper, and finally dried at 100 °C in vacuum for 12 h. After cooling to room temperature, the electrochemical properties of the materials were tested by cutting and assembling batteries. Example 5
[0049] A bimetallic MXenes (Mo2Ti2C3Tx ) Preparation method of a base hybrid anode material, comprising the following steps:
[0050] (1) Prepare multi-layered Mo2Ti2C3T x MXenes by pre-etching Mo2Ti2AlC3 MAX phase with hydrofluoric acid;
[0051] Prepare multi-layered Mo2Ti2C3T x MXenes by liquid-phase etching method, and the specific method is as follows:
[0052] Use Mo2Ti2AlC3 as the MXenes precursor and 49 wt% hydrofluoric acid as the etchant. First, place a polytetrafluoroethylene beaker with holes drilled at the edge of the cup wall in a water bath, then use a pipette to measure 15 mL of hydrofluoric acid and transfer it into the polytetrafluoroethylene beaker; weigh 2 g of Mo2Ti2AlC3 powder with a precision electronic balance, and then slowly add it to the hydrofluoric acid solution in small portions; cover the beaker lid after adding, and start the constant-temperature water bath stirring; after the pre-etching is completed, use deionized water and centrifuge at high speed until the supernatant is neutral. The water bath temperature is set at 50 °C, the pre-etching time is 72 h, and the stirring speed is set at 900 r / min.
[0053] (2) Use the hydrothermal method to perform secondary etching on multi-layered Mo2Ti2C3T x MXenes, and the specific method is as follows:
[0054] Use the aqueous solution of multi-layered Mo2Ti2C3T x MXenes as the precursor and thioacetamide as the sulfur source; take 30 mL of Mo2Ti2C3T x MXenes aqueous solution (concentration 1 mg / mL - 10 mg / mL) and place it in a beaker, add thioacetamide (0.01 g - 0.1 g), and the mass ratio of multi-layered MXenes to the sulfur source precursor is 9:10. Stir and mix for 30 min; transfer the evenly mixed solution into a polytetrafluoroethylene inner liner, and perform a hydrothermal reaction at 180 °C for 36 h. After the reaction is completed, naturally cool to room temperature, take out the solid-liquid mixture after the reaction, centrifuge and wash it 3 - 5 times, and freeze-dry to obtain the Mo2Ti2C3T x base hybrid anode material.
[0055] Pre-mix the Mo2Ti2C3T x base hybrid anode material prepared in this example, activated carbon, PVDF, etc. in a mortar evenly at a mass ratio of 80:10:10, then add NMP and grind to prepare a slurry with a certain viscosity, evenly coat it on the copper foil with a scraper, and finally dry it in vacuum at 100 °C for 12 h. After cooling to room temperature, cut the sheet and assemble it into a battery to test the electrochemical performance of the material. Example 6
[0056] This example is basically the same as Example 1, except that sodium sulfide is used as the sulfur source. Example 7
[0057] This example is basically the same as Example 1, except that thiourea is used as the sulfur source. Comparative Example 1
[0058] This example is basically the same as Example 1, except that in step (1), a multi-layer Mo2Ti2C3T x MXenes aqueous solution was prepared. Step (2) was not carried out, and it was directly freeze-dried and then made into a coin cell to test the electrical performance. The lithium storage specific capacity of the multi-layer Mo2Ti2C3T x MXenes anode material is relatively low, as Figure 3 shown.
[0059] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made in these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A preparation method of a bimetallic Mo2Ti2C3T x -based hybrid anode material for lithium-ion batteries, characterized in that This preparation method is carried out at a relatively low reaction temperature of <300 °C and in a sulfur-containing vapor atmosphere to perform secondary microstructure modification on pre-etched multi-layer Mo2Ti2C3T x MXenes, further exfoliating it into few-layer MXenes, and in the case of not requiring additional addition of metal salts of transition metal elements, in-situ constructing Ti x O y / Mo x S y transition metal compounds; The preparation method comprises the following steps: (1) Prepare multi-layer Mo2Ti2C3T by pre-etching the Mo2Ti2AlC3 MAX phase with hydrofluoric acid x MXenes Prepare multilayer Mo2Ti2C3T x MXenes by liquid-phase etching method, and the specific method is as follows: Using Mo2Ti2AlC3 as the MXenes precursor and 49 wt% hydrofluoric acid as the etching agent. First, place a polytetrafluoroethylene beaker with holes drilled at the edge of the cup wall in a water bath, and then use a pipette to measure 15 mL of hydrofluoric acid and transfer it into the polytetrafluoroethylene beaker. Weigh 2 g of Mo2Ti2AlC3 powder using a precision electronic balance, and then add it slowly to the hydrofluoric acid solution in small portions. After adding, cover the beaker lid and start stirring with a constant temperature water bath. After the pre-etching is completed, use deionized water and centrifuge at high speed until the supernatant is neutral. The water bath temperature is set at 55 °C, the pre-etching time is 96 h, and the stirring speed is set at 900 r / min; (2)Use the hydrothermal method to etch multi-layer Mo2Ti2C3T x MXenes for the second time, and the specific method is as follows: Using multi-layer Mo2Ti2C3T x MXene aqueous solution as the precursor and thioacetamide as the sulfur source; Take 30 mL of Mo2Ti2C3T x MXene aqueous solution and place it in a beaker, add thioacetamide, and the mass ratio of multi-layer MXene to the sulfur source precursor is 1:
10. Stir and mix for 30 min; Transfer the uniformly mixed solution into a polytetrafluoroethylene inner liner and carry out a hydrothermal reaction at 200 °C for 24 h; After the reaction, naturally cool to room temperature, take out the solid-liquid mixture after the reaction, centrifuge and wash it 3-5 times, and freeze-dry to obtain the Mo2Ti2C3T x based hybrid anode material.