Preparation method of bc-derived carbon-based nanofiber electrode material, electrode material and application

Abstract

The application discloses a BC-derived carbon-based nanofiber electrode material preparation method, an electrode material and application. The BC-derived carbon-based nanofiber electrode material preparation method comprises the following steps: etching preparation of MXene water dispersion by using an HCI-fluoride salt method; taking bacterial cellulose as a base material, adding an ammonium molybdate solution, sodium dihydrogen phosphate and the MXene dispersion into a culture medium by using an in-situ culture method, taking out and washing with deionized water after standing and culturing to obtain a BC / MXene / NaH2PO4 / Mo precursor hydrogel; adding the prepared BC / MXene / NaH2PO4 / Mo precursor into a thiourea solution for hydrothermal sulfidation, washing the obtained product by hydrothermal treatment with deionized water, and performing freeze-drying treatment to obtain a dried film; high-temperature carbonization of the dried film to obtain biomass interlayer modified BC-derived carbon / MXene / molybdenum disulfide nanofiber as a BC-derived carbon-based nanofiber electrode material. The method can alleviate the structure collapse and self-stacking problems of MoS2 in the charging and discharging process.

Description

Technical Field

[0001] This application relates to the field of nanofiber electrode material preparation technology, specifically to a method for preparing BC-derived carbon-based nanofiber electrode material, the BC-derived carbon-based nanofiber electrode material, and its applications. Background Technology

[0002] In recent years, lithium-ion batteries, characterized by high energy density and good cycle stability, have dominated the development of high-performance batteries. Therefore, further improvements in lithium-ion battery performance have been a major focus. However, traditional lithium-ion battery energy storage materials suffer from capacity decay and safety hazards, necessitating the exploration of novel high-performance energy storage materials. Among these, the application of nanofiber technology in the field of lithium-ion battery energy storage materials has attracted widespread attention and research.

[0003] Layered transition metal sulfides possess advantages such as high theoretical capacity, abundant natural resources, and environmental friendliness. Among them, molybdenum disulfide (MoS2) has become a potential alternative electrode material for lithium-ion batteries due to its excellent electrochemical, mechanical, and thermal properties. However, bulk MoS2, when used directly as a negative electrode material, exhibits poor conductivity, unsatisfactory long-cycle and rate performance, and carries the risk of battery capacity decay. These problems arise because MoS2 experiences volume expansion and self-stacking during cycling, which easily leads to varying degrees of damage to its layered structure.

[0004] Carbon materials are excellent substrates for buffering volume changes, and BC-based carbon is a superior material for self-supporting fibrous electrodes. Given the natural 3D network structure of BC nanofibers, many researchers have used BC-based carbon to load MoS2 nanosheets, providing MoS2 with 1D-scale rapid electron-ion transport channels and a 3D interconnected conductive network. However, most studies have loaded MoS2 nanosheets onto the outer surface of BC-based carbon fibers. While this provides continuous conductive pathways, it has little effect on mitigating MoS2 structural collapse and self-stacking.

[0005] Therefore, how to mitigate the collapse and self-stacking of MoS2 structures and further expand their interlayer spacing to improve the electrochemical performance of lithium-ion batteries is an urgent technical problem to be solved.

[0006] Therefore, there is a need for a technical solution to address or at least mitigate the aforementioned shortcomings of existing technologies. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing BC-derived carbon-based nanofiber electrode materials to at least solve one of the above-mentioned technical problems.

[0008] One aspect of the present invention provides a method for preparing a BC-derived carbon-based nanofiber electrode material, the method comprising:

[0009] MXene aqueous dispersions were prepared by etching using the HCl-fluoride salt method;

[0010] Using bacterial cellulose as a substrate, ammonium molybdate solution, sodium dihydrogen phosphate and the MXene dispersion were added to the culture medium in situ. After static culture, the culture was taken out and washed with deionized water to obtain BC / MXene / NaH2PO4 / Mo precursor hydrogel.

[0011] The prepared BC / MXene / NaH2PO4 / Mo precursor was added to a thiourea solution for hydrothermal sulfidation. The product obtained by hydrothermal treatment was washed with deionized water and then freeze-dried to obtain a dried membrane.

[0012] The dried membrane was carbonized at high temperature to obtain biomass interlayer modified BC-derived carbon / MXene / molybdenum disulfide nanofibers, which were used as BC-derived carbon-based nanofiber electrode materials.

[0013] Optionally, the preparation of the MXene aqueous dispersion by etching using the HCl-fluoride salt method includes:

[0014] MXene aqueous dispersion was prepared by stirring and etching at a first preset temperature for a first preset time and then centrifuging, using hydrochloric acid, lithium fluoride and Ti3AlC2 as raw materials.

[0015] Optionally, the addition of ammonium molybdate solution, sodium dihydrogen phosphate, and the MXene dispersion to the culture medium via in-situ culture includes:

[0016] Ammonium molybdate solution and NaH2PO4 were added to the culture medium. After a thin film grew on the surface of the culture medium, MXene dispersion was added to the culture medium.

[0017] Optionally, the first preset temperature is 35°C;

[0018] The first preset time is 12 hours;

[0019] The centrifugation speed was 3500 r / min and the centrifugation time was 3 min.

[0020] Optionally, the culture medium is cultured at 30°C;

[0021] The culture medium consists of 30 g / L mannitol, 5 g / L yeast extract, and 3 g / L tryptone.

[0022] The ammonium molybdate solution has a mass fraction of 3%, 5%, or 7%.

[0023] The concentration of NaH2PO4 is one of the following: 3 g / L, 6 g / L, 9 g / L, 12 g / L, 18 g / L, or 24 g / L;

[0024] The MXene dispersion has a mass fraction of 0.25%.

[0025] Optionally, the hydrothermal sulfidation conditions are as follows:

[0026] The thiourea solution has a mass fraction of 2.5%.

[0027] The hydrothermal temperature is 100℃, 150℃, or 200℃;

[0028] The hydrothermal treatment time is 12 hours.

[0029] Optionally, the high-temperature carbonization conditions are as follows:

[0030] The high-temperature carbonization conditions were as follows: heating to 240℃ at a rate of 1℃ / min, holding for 1 hour, then heating to 600℃ at a rate of 3℃ / min, and holding for 2 hours.

[0031] This application also provides a BC-derived carbon-based nanofiber electrode material, which is prepared by the preparation method of the BC-derived carbon-based nanofiber electrode material described above.

[0032] This application also provides an application of BC-derived carbon-based nanofiber electrode materials prepared by the above-described method in the field of energy storage.

[0033] The preparation method of the BC-derived carbon-based nanofiber electrode material in this application has the following advantages:

[0034] (1) Using a three-dimensional BC-derived carbon nanofiber network as a substrate is beneficial for loading two-dimensional layered MoS2 and MXene and enhancing the stability of the interlayer structure, thus alleviating the structural collapse and self-stacking problems of MoS2 during charging and discharging.

[0035] (2) The addition of MXene firmly anchors MoS2 nanosheets within the MXene layers. This unique interlayer confinement effect allows for control over the size and number of layers of the MoS2 nanosheets, and the in-situ formed heterostructure effectively improves ion transport dynamics. The excellent conductivity of MXene not only solves the problem of poor conductivity of MoS2 as a semiconductor, but also enhances the overall mechanical properties of the fiber network by forming a stable structure between MXene nanosheets and BC through hydrogen bonding.

[0036] (3) The addition of flame-retardant NaH2PO4 further "strengthens" the three-dimensional network of BC during the subsequent carbonization process.

[0037] (4) The synergistic effect between MoS2, MXene and BC-derived carbon enables the prepared BC-derived carbon / MXene / MoS2 nanofibers to be used as negative electrode materials for lithium-ion batteries, exhibiting excellent electrochemical performance. Attached Figure Description

[0038] Figure 1 This is a schematic flowchart illustrating a method for preparing a BC-derived carbon-based nanofiber electrode material according to an embodiment of this application.

[0039] Figure 2 The images shown are scanning electron microscope (SEM) images of MXene prepared in one embodiment of this application, wherein (a) is an MXene image at 5000x magnification and (b) is an MXene image at 10000x magnification.

[0040] Figure 3 This is a scanning electron microscope image of the BC-derived carbon-based nanofiber electrode material prepared in one embodiment of this application.

[0041] Figure 4 Impedance plot of a button cell assembled with BC-derived carbon-based nanofiber electrode material as the negative electrode, as shown in one embodiment of this application.

[0042] Figure 5 Cyclic voltammetry curves plotted for testing a button cell assembled with BC-derived carbon-based nanofiber electrode material as the negative electrode in one embodiment of this application.

[0043] Figure 6 The voltage-charge-discharge specific capacity image is plotted for testing a button cell assembled with BC-derived carbon-based nanofiber electrode material as the negative electrode in one embodiment of this application.

[0044] Figure 7 The image shows the efficiency-discharge specific capacity of a button cell assembled with BC-derived carbon-based nanofiber electrode material as the negative electrode, as described in one embodiment of this application. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0046] Figure 1 This is a schematic flowchart illustrating a method for preparing a BC-derived carbon-based nanofiber electrode material according to an embodiment of this application.

[0047] Example 1:

[0048] like Figure 1 The preparation method of the BC-derived carbon-based nanofiber electrode material shown includes:

[0049] MXene aqueous dispersions were prepared by etching using the HCl-fluoride salt method;

[0050] Using bacterial cellulose as a substrate, ammonium molybdate solution, sodium dihydrogen phosphate and the MXene dispersion were added to the culture medium in situ. After static culture, the culture was taken out and washed with deionized water to obtain BC / MXene / NaH2PO4 / Mo precursor hydrogel.

[0051] The prepared BC / MXene / NaH2PO4 / Mo precursor was added to a thiourea solution for hydrothermal sulfidation. The product obtained by hydrothermal treatment was washed with deionized water and then freeze-dried to obtain a dried membrane.

[0052] The dried membrane was carbonized at high temperature to obtain biomass interlayer modified BC-derived carbon / MXene / molybdenum disulfide nanofibers, which were used as BC-derived carbon-based nanofiber electrode materials.

[0053] In this embodiment, the preparation of MXene aqueous dispersion by etching using the HCl-fluoride salt method includes:

[0054] MXene aqueous dispersion was prepared by stirring and etching at a first preset temperature for a first preset time and then centrifuging, using hydrochloric acid, lithium fluoride and Ti3AlC2 as raw materials.

[0055] In this embodiment, the addition of ammonium molybdate solution, sodium dihydrogen phosphate, and the MXene dispersion to the culture medium via in-situ culture includes:

[0056] Ammonium molybdate solution and NaH2PO4 were added to the culture medium. After a thin film grew on the surface of the culture medium, MXene dispersion was added to the culture medium.

[0057] In this embodiment, the first preset temperature is 35°C;

[0058] The first preset time is 12 hours;

[0059] The centrifugation speed was 3500 r / min and the centrifugation time was 3 min.

[0060] In this embodiment, the culture medium is cultured at 30°C;

[0061] The culture medium consists of 30 g / L mannitol, 5 g / L yeast extract, and 3 g / L tryptone.

[0062] The ammonium molybdate solution has a mass fraction of 3%, 5%, or 7%.

[0063] The concentration of NaH2PO4 is one of the following: 3 g / L, 6 g / L, 9 g / L, 12 g / L, 18 g / L, or 24 g / L;

[0064] The MXene dispersion has a mass fraction of 0.25%.

[0065] In this embodiment, the hydrothermal sulfidation conditions are as follows:

[0066] The thiourea solution has a mass fraction of 2.5%.

[0067] The hydrothermal temperature is 100℃, 150℃, or 200℃;

[0068] The hydrothermal treatment time is 12 hours.

[0069] In this embodiment, the high-temperature carbonization conditions are as follows:

[0070] The high-temperature carbonization conditions were as follows: heating to 240℃ at a rate of 1℃ / min, holding for 1 hour, then heating to 600℃ at a rate of 3℃ / min, and holding for 2 hours.

[0071] Example 2:

[0072] A method for preparing a BC-derived carbon-based nanofiber electrode material includes the following steps:

[0073] Step (1): MXene was prepared by etching with 60 mL of 0.9 M concentrated hydrochloric acid, 4.8 g of lithium fluoride and 3 g of Ti3AlC2 as raw materials, stirred at 35 °C for 24 h and centrifuged at 3500 r / min for 3 minutes. Figure 2The image shows a scanning electron microscope (SEM) image of the prepared MXene.

[0074] Step (2): Prepare a culture medium with 30 g / L mannitol, 5 g / L yeast powder and 3 g / L tryptone. Add 5% ammonium molybdate solution, 2.5% MXene dispersion and 12 g / L NaH2PO4 to the culture medium. Inoculate 5 mL of Acetobacter xyloside culture. After static culture for several days, take it out and wash it with deionized water to obtain BC / MXene / NaH2PO4 / Mo precursor hydrogel.

[0075] Step (3): The prepared BC / MXene / NaH2PO4 / Mo precursor was added to a 0.25% thiourea solution and hydrothermally sulfided at 150°C for 12 h. The product obtained by hydrothermal treatment was washed with deionized water and then freeze-dried to obtain dried BC / MXene / NaH2PO4 / MoS2.

[0076] Step (4): The dried membrane was placed in a protective argon atmosphere for high-temperature carbonization. The high-temperature carbonization conditions were: heating to 240°C at a rate of 1°C / min, holding for 1 hour, then heating to 600°C at a rate of 3°C / min, and holding for 2 hours to obtain the biomass interlayer modified BC-derived carbon / MXene / MoS2 nanofibers. Figure 4 Scanning electron microscope (SEM) image of the prepared BC-derived carbon / MXene / MoS2 nanofibers.

[0077] In this embodiment, the present application further includes a BC-derived carbon-based nanofiber electrode material, which is prepared by the preparation method of the BC-derived carbon-based nanofiber electrode material as described above.

[0078] In this embodiment, the application further includes the application of BC-derived carbon-based nanofiber electrode materials prepared by the above-described method in the field of energy storage.

[0079] In this embodiment, the energy storage field includes button batteries.

[0080] In this embodiment, the BC-derived carbon-based nanofiber electrode material of this application is used as the negative electrode of a coin cell. The specific fabrication method is as follows: the prepared BC-derived carbon / MXene / MoS2 nanofibers are cut into circular electrode sheets with a diameter of 12 mm using a disc cutter and used as the negative electrode. A lithium metal sheet is used as the counter electrode, a microporous polypropylene membrane is used as the separator, and a 1 mol / L LiPF6 solution is used as the electrolyte to assemble the coin cell and test its electrochemical performance. Figure 4-7 This is a characterization diagram of the electrochemical tests performed on the button cell.

[0081] This invention involves adding ammonium molybdate solution and conductive MXene and flame-retardant NaH2PO4 to BC culture medium via in-situ culture to prepare a BC / MXene / NaH2PO4 / Mo precursor hydrogel through interlayer modification of biomass. After freeze-drying the precursor hydrogel to maintain its pore structure, hydrothermal vulcanization combined with high-temperature carbonization in an inert gas is used to improve the crystallinity of MoS2, thereby obtaining BC-derived carbon / MXene / MoS2 nanofibers that possess both conductivity and flexibility.

[0082] This invention successfully introduces MoS2 nanosheets and MXene into the interior of BC-based carbon fibers to prepare a BC-derived carbon / MXene / MoS2 nanofiber network. In this structure, due to the chemical bonding between the BC functional groups and the Mo precursor, as well as the hydrogen bonding with MXene, the BC-derived carbon is intercalated in situ between the MoS2 and MXene layers, which can enhance the stability of the two-dimensional interlayer structure and alleviate the self-stacking phenomenon of its layered structure.

[0083] The Mo-C covalent bonds firmly anchor the MoS2 nanosheets within the MXene layers. This unique interlayer confinement effect allows for control over the size and number of MoS2 nanosheets, and the in-situ formed heterostructure effectively enhances ion transport kinetics. BC-derived carbon nanofibers act as a "bridging" structure connecting the layered MXene, while also providing additional nucleation sites for the Mo precursor to load the MoS2 nanosheets. The dense MXene nanosheets interspersed between the fibers form a stable structure with BC through hydrogen bonding, thereby enhancing the overall mechanical properties of the fiber network.

[0084] Therefore, the composite of MoS2, MXene, and BC-based derived carbon can effectively alleviate the structural collapse and self-stacking problems of MoS2 during charge and discharge, expand its interlayer spacing, and effectively improve ion transport kinetics. Moreover, the use of MXene to increase conductivity solves the problem of poor conductivity of MoS2 as a semiconductor.

[0085] The added NaH2PO4, with its flame-retardant properties, further reinforces the three-dimensional network of BC during subsequent carbonization, enhancing the strength and structural stability of the BC-derived carbon / MXene / MoS2 nanofibers, making them less prone to breakage and brittle fracture, thus facilitating subsequent practical applications. Finally, the prepared BC-derived carbon / MXene / MoS2 nanofibers were used as a negative electrode material for lithium-ion batteries, exhibiting excellent electrochemical performance.

[0086] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Moreover, it is clear that the word "comprising" does not exclude other units or steps. The multiple units, modules, or devices recited in the apparatus claims may also be implemented by a single unit or overall apparatus via software or hardware.

[0087] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a BC-derived carbon-based nanofiber electrode material, characterized in that, The preparation method of the BC-derived carbon-based nanofiber electrode material includes: MXene aqueous dispersions were prepared by etching using the HCl-fluoride salt method; Using bacterial cellulose as a substrate, ammonium molybdate solution, sodium dihydrogen phosphate and MXene aqueous dispersion were added to the culture medium in situ. After static culture, the culture medium was taken out and rinsed with deionized water to obtain BC / MXene / NaH2PO4 / Mo precursor hydrogel. The prepared BC / MXene / NaH2PO4 / Mo precursor was added to a thiourea solution for hydrothermal sulfidation. The product obtained by hydrothermal treatment was washed with deionized water and then freeze-dried to obtain a dried membrane. The dried membrane was carbonized at high temperature to obtain biomass interlayer modified BC-derived carbon / MXene / molybdenum disulfide nanofibers as BC-derived carbon-based nanofiber electrode materials. The addition of ammonium molybdate solution, sodium dihydrogen phosphate, and MXene aqueous dispersion to the culture medium via in-situ culture includes: Ammonium molybdate solution and NaH2PO4 were added to the culture medium. After a thin film grew on the surface of the culture medium, MXene aqueous dispersion was added to the culture medium.

2. The method for preparing the BC-derived carbon-based nanofiber electrode material as described in claim 1, characterized in that, The preparation of MXene aqueous dispersion by etching using the HCl-fluoride salt method includes: MXene aqueous dispersion was prepared by stirring and etching at a first preset temperature for a first preset time and then centrifuging, using hydrochloric acid, lithium fluoride and Ti3AlC2 as raw materials.

3. The method for preparing the BC-derived carbon-based nanofiber electrode material as described in claim 2, characterized in that, The first preset temperature is 35°C; The first preset time is 12 hours; The centrifugation speed was 3500 r / min and the centrifugation time was 3 min.

4. The method for preparing the BC-derived carbon-based nanofiber electrode material as described in claim 2, characterized in that, The culture medium was cultured at 30°C. The culture medium consists of 30 g / L mannitol, 5 g / L yeast extract, and 3 g / L tryptone. The ammonium molybdate solution has a mass fraction of 3%, 5%, or 7%. The concentration of NaH2PO4 is one of the following: 3 g / L, 6 g / L, 9 g / L, 12 g / L, 18 g / L, or 24 g / L; The mass fraction of the MXene aqueous dispersion is 0.25%.

5. The method for preparing the BC-derived carbon-based nanofiber electrode material as described in claim 1, characterized in that, The hydrothermal sulfidation conditions are as follows: The mass fraction of the thiourea solution is 2.5%. The hydrothermal temperature is 100℃, 150℃, or 200℃; The hydrothermal treatment time was 12 hours.

6. The method for preparing the BC-derived carbon-based nanofiber electrode material as described in claim 1, characterized in that, The high-temperature carbonization conditions are as follows: The high-temperature carbonization conditions were as follows: heating to 240°C at a rate of 1°C / min, holding for 1 h, followed by heating to 600°C at a rate of 3°C / min, and holding for 2 h.

7. A BC-derived carbon-based nanofiber electrode material, characterized in that, The BC-derived carbon-based nanofiber electrode material is prepared using the preparation method of the BC-derived carbon-based nanofiber electrode material as described in any one of claims 1 to 6.

8. The application of the BC-derived carbon-based nanofiber electrode material prepared by the preparation method of any one of claims 1 to 6 in the field of energy storage.

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