A lithium negative electrode material Mo2C / NiO@GO carbon nanofiber and a preparation method thereof

Abstract

The application discloses a preparation method of a lithium battery negative electrode material Mo2C / NiO@GO carbon nanofiber, and comprises the following steps: S1, weighing nickel oxide, ammonium molybdate tetrahydrate and a solvent and performing ultrasonic treatment; S2, weighing a high-molecular surfactant, adding the high-molecular surfactant into a beaker and stirring at normal temperature to obtain a spinning solution; S3, adopting a needle tube to suck the spinning solution and performing electrostatic spinning to obtain a precursor, taking down the precursor after spinning is completed, and drying the precursor in an oven; S4, pre-sintering the dried precursor; S5, performing suction filtration on the pre-sintered precursor; and performing heat treatment on the suction filtration and drying precursor to obtain the required lithium ion battery negative electrode material. The preparation method of the application obtains the Mo2C / NiO@GO material with a three-dimensional network structure, improves the specific surface area and the conductivity of the negative electrode material, and the obtained battery has high specific capacity and good cycle stability, and has significant economic value.

Description

Technical Field

[0001] This invention relates to a method for preparing a battery anode material, specifically a lithium-ion battery anode material Mo2C / NiO@GO carbon nanofiber and its preparation method, belonging to the field of nanomaterial synthesis and battery preparation. Background Technology

[0002] Lithium-ion batteries (LIBs) are currently the most common rechargeable electrochemical energy storage systems, widely used in portable electronic devices and new energy vehicles. A lithium-ion battery mainly consists of a positive electrode, a negative electrode, and a separator. Improving the structure and performance of the negative electrode material can effectively enhance the electrochemical performance of LIBs. Currently, the most widely used negative electrode material is graphite carbon, which has good stability but poor rate performance and a low theoretical specific capacity of only 372 mAh g⁻¹. -1 This severely restricts the electrochemical performance of LIBs and limits their further development, making the development of next-generation lithium battery anode materials an urgent priority.

[0003] Transition metal oxides, represented by nickel oxide, have a very high theoretical specific capacity (718 mAh g⁻¹). -1 Molybdenum carbide (MCC) is abundant in the Earth's crust, making it suitable for large-scale industrial use and a promising candidate for future excellent anode materials, attracting widespread attention. However, its current applications are limited by its extremely low conductivity, while molybdenum-based carbides, in addition to possessing a high theoretical specific capacity (600 mAh g / g), are a different story. -1 -1000mAhg -1 In addition to its excellent electrical conductivity (1.02×10⁻⁶), it also possesses remarkable electrical conductivity. 2 The conductivity (S / cm) of nickel-based anode materials can be effectively improved by adding molybdenum doping to nickel oxide. However, during charge and discharge, the significant volume change of nickel oxide during alloying / dealloying reactions leads to the fragmentation of active material particles, resulting in rigid cracks at the solid-electrolyte interface and the shedding of active material powder from the current collector. This ultimately reduces electrode capacity and shortens battery life. To improve battery lifespan, it is necessary to mitigate the volume expansion of nickel anode materials during lithium-ion insertion / extraction.

[0004] Studies have shown that designing hollow nanostructures from multi-element transition metal oxides is widely considered an effective solution. By controlling the structure and size of the material, the diffusion path of lithium ions can be shortened by the unique hollow nanostructure, effectively alleviating the severe volume expansion problem that occurs during lithium delithiation and lithium insertion, thus improving battery performance. Furthermore, graphene, a 2D carbon material formed by sp hybridization of C atoms, has a specific surface area of ​​2630 mg, and also exhibits high thermal conductivity and mechanical strength. Graphene can serve as a good conductive additive and thermal conductive material, further improving the overall conductivity of the material and facilitating thermal diffusion of the electrode during charge-discharge cycles. Secondly, the medium- and two-dimensional nanostructures of graphene can act as natural conductors for active materials, and its unique mechanical properties can alleviate the problem of material volume change, achieving the goal of simultaneously improving rate capability and cycle performance. Therefore, Mo2C / NiO@GO carbon nanofibers are composite anode materials with great application potential.

[0005] Currently, there is almost no research on Mo2C / NiO@GO composite materials. Patent application CN201510661685.9, entitled "A Method for Preparing Molybdenum Oxide / Nickel / Carbon Composite Anode Material for Lithium-ion Batteries," describes a method for synthesizing molybdenum oxide / nickel-carbon composite anode material using chemical vapor deposition. While the preparation method is simple, it cannot solve the problem of poor cycle stability caused by volume changes during alloying / dealloying reactions of metal oxides. Furthermore, this method has limited production scale, and the samples produced by hydrothermal methods have poor consistency. Patent application CN201910158517.6, entitled "A Method for Preparing Nickel Molybdate Doped Carbon Quantum Dot Lithium-ion Battery Anode Material," describes a simple method for preparing NiMoO4 nanoparticles, but it does not address the low cycle life problem caused by the low conductivity and poor lithium-ion transport kinetics of binary metal oxides. Based on these conclusions, there is an urgent need for a novel method for preparing lithium-ion battery anode materials. Summary of the Invention

[0006] To address the problems existing in the prior art, the purpose of this invention is to provide a method for preparing Mo2C / NiO@GO, a lithium-ion battery anode material, in order to solve the problems of low specific capacity, high production energy consumption, and difficulty in large-scale production that exist in the current lithium-ion battery manufacturing process.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing Mo2C / NiO@GO nanofibers as lithium-ion battery anode material includes the following steps:

[0009] S1: Weigh out nickel oxide, ammonium molybdate tetrahydrate and solvent, add them to a beaker in sequence, cover with plastic wrap and then perform ultrasonic treatment. The ultrasonic power is 150-550W and the ultrasonic time is 10-120min. The molar ratio of nickel oxide, ammonium molybdate tetrahydrate and solvent is in the range of 1:3 to 1:1.

[0010] S2: Weigh the polymeric surfactant and add it to the beaker in step S1. Stir at room temperature to obtain the desired spinning solution. Stir for 8-24 hours at a stirring speed of 100-600 r / min.

[0011] S3: Electrospinning is performed using a syringe to draw up the spinning solution to obtain the precursor. The spinning voltage is 10-25V, the syringe advance speed is 0.2-1.0mL / h, and the receiving distance is 13-20cm. After spinning is completed, the precursor is removed and dried in an oven at 60-90℃ for 6-24h.

[0012] S4: The dried precursor from step S3 is pre-sintered at a temperature of 200–300°C for 0.5–2 h, with a heating rate of 0.5–5°C / min and an atmosphere of air.

[0013] S5: The precursor pre-sintered in step S4 is subjected to vacuum filtration. The solvent is graphene oxide dispersion with a concentration of 0.2-1 mg / mL. The filtration time is 3-60 min. The corresponding membrane material is selected according to the solvent, and the pore size of the filter membrane is less than 1 μm.

[0014] S6: Next, it is subjected to high-temperature heat treatment at a temperature of 600-900℃, a holding time of 1-4h, a heating rate of 1-5℃ / min, and an inert atmosphere. After the high-temperature heat treatment, the desired lithium-ion battery anode material Mo2C / NiO@GO is obtained.

[0015] Optionally, in step S1, the solvent may be one or a mixture of N-dimethylformamide (DMF), alcohol, and dimethyl sulfoxide (DMSO).

[0016] Optionally, the polymeric surfactant in step S2 is one of polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), or polyacrylonitrile (PAN).

[0017] Optionally, in step S5, the solvent for the graphene dispersion is one or a mixture of deionized water, N-dimethylformamide (DMF), and alcohol.

[0018] Optionally, the inert gas used in the high-temperature heat treatment in step S6 is one of argon and nitrogen, or a mixture of both.

[0019] A lithium-ion battery anode material, Mo2C / NiO@GO carbon nanofiber, is prepared by the above-mentioned preparation method of lithium-ion anode material Mo2C / NiO@GO carbon nanofiber.

[0020] The beneficial effects of the preparation method of the present invention are as follows:

[0021] (1) The lithium battery anode material Mo2C / NiO@GO obtained by the method of the present invention is a pure phase with a nanowire morphology and a diameter of 50-300 nm. It has very few doped impurities, and the morphology of the nanowires provides a larger specific surface area for the electrochemical reaction process. The pure phase ensures more stable electrochemical performance such as discharge specific capacity and rate performance.

[0022] (2) The lithium battery anode material Mo2C / NiO@GO obtained by the method of the present invention is assembled into a lithium-ion battery. In the voltage range of 0 to 3V, the initial discharge specific capacity can reach as high as 1127mAh / g at a current density of 100mA / g. At a current density of 500mA / g, its initial reversible discharge specific capacity can still reach 1084mAh / g. In the 0-30 cycles, the charge-discharge specific capacity of the battery continuously decreases, dropping to a minimum of 633.5mAh / g. However, as the cycle continues for 500 cycles, the crystallinity of the graphite layer decreases after repeated lithium insertion and extraction, and more active sites are exposed between the layers, reaching 1092mAh / g, which is close to the initial discharge efficiency. This effect has not been found in other inventions.

[0023] (3) The method of the present invention has a short process, simple operation, low cost, strong controllability, good repeatability, wide applicability, and is suitable for industrial production. Attached Figure Description

[0024] Figure 1 The image shows the XRD pattern of the lithium-ion battery anode material Mo2C / NiO@GO obtained in Example 1 of this invention.

[0025] Figure 2 This is a SEM image of the Mo2C / NiO@GO lithium-ion battery anode material obtained in Example 1 of this invention;

[0026] Figure 3 The rate performance diagram shows the lithium-ion battery assembled from the Mo2C / NiO@GO lithium-ion battery anode material obtained in Example 1 of this invention.

[0027] Figure 4 The graph shows the charge-discharge cycle performance of a lithium-ion battery assembled from the Mo2C / NiO@GO lithium-ion battery anode material obtained in Example 1 of this invention. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings, but this is not limited to the scope of protection of the present invention.

[0029] Example 1

[0030] (1) Weigh 1 mmol of nickel oxide, 1 mmol of ammonium molybdate tetrahydrate and 12 g of DMSO solution, add them to a beaker in sequence, seal the bottle mouth with plastic wrap, and perform ultrasonic dispersion at 150 W for 10 min.

[0031] (2) Weigh 1.25g PVP and add it to the solution that has been ultrasonically dispersed in step (1) and stir for 8 hours at a temperature of 20℃ and a stirring speed of 600r / min to obtain the spinning solution.

[0032] (3) Electrospinning was performed by drawing the spinning solution with a syringe. The spinning voltage was 18V, the syringe advance speed was 0.2mL / h, the receiving distance was 13cm, and the precursor was obtained after spinning for 12h. After removing it, it was dried in an oven at 60℃ for 24h.

[0033] (4) The precursor dried in step (3) is pre-sintered at a temperature of 250°C, a holding time of 1 h, a heating rate of 3°C / min, and an atmosphere of air.

[0034] (5) The pre-sintered precursor in step (4) was subjected to vacuum filtration. The solvent was a deionized graphene oxide aqueous dispersion with a concentration of 0.2 mg / mL. The filtration time was 20 min, and an aqueous filter membrane with a pore size of 0.45 μm was used. The filtered precursor was dried in an oven at 70 °C for 12 h.

[0035] (6) The precursor dried in step (5) is subjected to high-temperature heat treatment at a temperature of 600℃ for 1 hour, with a heating rate of 1℃ / min and an argon atmosphere. After the high-temperature heat treatment, the desired lithium-ion battery anode material Mo2C / NiO@GO is obtained.

[0036] like Figure 1 As shown, the peak values ​​of the lithium-ion battery anode material Mo2C / NiO@GO obtained in this embodiment on XRD are basically consistent with those of the standard Mo2C (PDF#79-0744) and NiO (PDF#89-7390), which confirms that the obtained material is a composite material of Mo2C and NiO.

[0037] like Figure 2 As shown, the lithium-ion battery anode material Mo2C / NiO@GO obtained in this embodiment has a uniform morphology, and the main body is composed of nanowires with a diameter of 100 nm, with sheet-like graphene distributed in between.

[0038] Battery Assembly: 0.60g of the lithium-ion battery anode material Mo2C / NiO@GO obtained in this example was weighed as the anode material. 0.075g of acetylene black (SP) was added as a conductive agent, and 0.075g of PVDF (HSV-900) was added as a binder. After thorough grinding, 3mL of NMP was added for dispersion and mixing. The mixture was then stretched onto a 16μm thick copper foil to form the anode sheet. Using a lithium metal sheet as the positive electrode, a CELGARD2300 polypropylene microporous membrane as the separator, and 1mol / L LiPF6 / EC:DMC (volume ratio 1:1) as the electrolyte, a CR2032 coin cell was assembled in a high-purity argon glove box. The constant current charge-discharge performance of the assembled lithium-ion battery was tested within the voltage range of 0–3V.

[0039] like Figure 3 As shown, at a current density of 100 mA / g, the initial discharge capacity can reach as high as 1127 mAh / g, the initial charge-discharge efficiency is 75.44%, and it has good cycle stability.

[0040] like Figure 4 As shown, at a current density of 500 mA / g, its initial reversible discharge specific capacity can still reach 1084 mAh / g, and the initial charge-discharge efficiency is 81.22%. The charge-discharge cycle diagram for 500 cycles shows that the battery's charge-discharge specific capacity continuously decreases from 0 to 30 cycles, reaching a minimum of 633.5 mAh / g. This is mainly due to the formation of an SEI passivation film and lithium metal deposition on the positive and negative electrode surfaces. After 30 cycles, the battery's charge-discharge specific capacity continuously increases, reaching a maximum of 1092 mAh / g, approaching the initial discharge efficiency. This is because, with each cycle, the electrolyte fully wets the electrode, and the repeated lithium insertion / extraction of the graphite layer reduces crystallinity, exposing more active sites between layers.

[0041] As can be seen from the above, the lithium-ion battery assembled with the lithium-ion battery anode material Mo2C / NiO@GO obtained in the embodiments of the present invention has high specific capacity and good cycle stability.

[0042] Example 2

[0043] (1) Weigh 7 mmol of nickel oxide, 1 mmol of ammonium molybdate tetrahydrate and 9 g of DMF solution, add them to a beaker in sequence, seal the bottle mouth with plastic wrap, and perform ultrasonic dispersion at 300 W for 60 min.

[0044] (2) Weigh 1.40g PVP and add it to the solution that has been ultrasonically dispersed in step (1). Stir at 20℃ for 12h at a stirring speed of 500r / min to obtain the spinning solution.

[0045] (3) Electrospinning was performed by drawing the spinning solution with a syringe. The spinning voltage was 17.26V, the syringe advance speed was 0.5mL / h, the receiving distance was 15cm, and the precursor was obtained after spinning for 12h. After removing it, it was dried in an oven at 70℃ for 16h.

[0046] (4) The precursor dried in step (3) is pre-sintered at a temperature of 300℃, a holding time of 30min, a heating rate of 5℃ / min, and an atmosphere of air.

[0047] (5) The pre-sintered precursor in step (4) was subjected to vacuum filtration. The solvent was a deionized graphene oxide aqueous dispersion with a concentration of 0.5 mg / mL. The filtration time was 3 min, and an aqueous filter membrane with a pore size of 0.45 μm was used. The filtered precursor was dried in an oven at 70 °C for 12 h.

[0048] (6) The precursor dried in step (5) is subjected to high-temperature heat treatment at a temperature of 750°C for 3 hours, with a heating rate of 3°C / min and a nitrogen-argon mixture atmosphere (1:1). After the high-temperature heat treatment, the desired lithium-ion battery anode material Mo2C / NiO@GO is obtained.

[0049] After phase analysis, the peak values ​​of the lithium battery anode material Mo2C / NiO@GO obtained in this embodiment on XRD are basically consistent with those of the standard, and there are no impurity peaks. It can be determined that the obtained anode material is a composite material of Mo2C and NiO.

[0050] The lithium-ion battery anode material Mo2C / NiO@GO obtained in this embodiment has a uniform morphology and consists of nanowires with a diameter of 50-150 nm.

[0051] Battery assembly: Same as in Example 1. The constant current charge-discharge performance of the assembled lithium-ion battery was tested within a voltage range of 0–3V.

[0052] At a current density of 100 mA / g, the initial discharge capacity can reach up to 1112.6 mAh / g, the initial charge-discharge efficiency is 78.56%, and the coulombic efficiency is stable.

[0053] At a current density of 500 mA / g, its initial reversible discharge specific capacity can still reach 1030.3 mAh / g, and after 250 cycles, its discharge specific capacity can reach 816 mAh / g.

[0054] As can be seen from the above, the lithium-ion battery assembled with the lithium-ion battery anode material Mo2C / NiO@GO obtained in the embodiments of the present invention has high specific capacity and good cycle stability.

[0055] Example 3

[0056] (1) Weigh 7 mmol of nickel oxide, 0.5 mmol of ammonium molybdate tetrahydrate and 9 g of alcohol solution, add them to a beaker in sequence, seal the bottle mouth with plastic wrap, and perform ultrasonic dispersion at 550 W for 120 min.

[0057] (2) Weigh 1.4g of PVP and add it to the solution that has been ultrasonically dispersed in step (1). Stir at 20℃ for 16h at a stirring speed of 300r / min to obtain the spinning solution.

[0058] (3) Electrospinning was performed by drawing the spinning solution with a syringe. The spinning voltage was 19.3V, the syringe advance speed was 0.7mL / h, the receiving distance was 17cm, and the precursor was obtained after spinning for 12h. After removing it, it was dried in an oven at 90℃ for 6h.

[0059] (4) The precursor dried in step (3) is pre-sintered at a temperature of 200℃, a holding time of 2h, a heating rate of 0.5℃ / min, and an atmosphere of air.

[0060] (5) The pre-sintered precursor in step (4) was subjected to vacuum filtration. The solvent was a deionized water dispersion of graphene oxide with a concentration of 0.8 mg / mL. The filtration time was 40 min, and an aqueous filter membrane with a pore size of 0.45 μm was used. The filtered precursor was dried in an oven at 70 °C for 12 h.

[0061] (6) The precursor dried in step (5) is subjected to high-temperature heat treatment at a temperature of 900℃ for 1 hour, with a heating rate of 3℃ / min and a nitrogen atmosphere. After the high-temperature heat treatment, the desired lithium-ion battery anode material Mo2C / NiO@GO is obtained.

[0062] After phase analysis, the peak values ​​of the lithium battery anode material Mo2C / NiO@GO obtained in this embodiment on XRD are basically consistent with those of the standard, and there are no impurity peaks. It can be determined that the obtained anode material is a composite material of Mo2C and NiO.

[0063] The lithium-ion battery anode material Mo2C / NiO@GO obtained in this embodiment has a uniform morphology and consists of nanowires with a diameter of 50-150 nm.

[0064] Battery assembly: Same as in Example 1. The constant current charge-discharge performance of the assembled lithium-ion battery was tested within a voltage range of 0–3V.

[0065] At a current density of 100 mA / g, the initial discharge capacity can reach as high as 1151.5 mAh / g, and the coulombic efficiency is stable.

[0066] At a current density of 500 mA / g, its initial reversible discharge specific capacity can still reach 997.6 mAh / g, and after 250 cycles, its discharge specific capacity can still reach 715.4 mAh / g, with a capacity retention rate of 71.7%.

[0067] As can be seen from the above, the lithium-ion battery assembled with the lithium-ion battery anode material Mo2C / NiO@GO obtained in the embodiments of the present invention has high specific capacity and good cycle stability.

[0068] Example 4

[0069] (1) Weigh 1 mmol of nickel oxide, 1 mmol of ammonium molybdate tetrahydrate, 9 g of DMF solution and 2 g of alcohol solution, add them to a beaker in sequence, seal the bottle mouth with plastic wrap, and perform ultrasonic dispersion at 300 W for 100 min.

[0070] (2) Weigh 1.4g PVP and add it to the solution that has been ultrasonically dispersed in step (1) and stir at 20℃ for 24h at a stirring speed of 100r / min to obtain the spinning solution.

[0071] (3) Electrospinning was performed by drawing the spinning solution with a syringe. The spinning voltage was 10V, the syringe advance speed was 1.0mL / h, the receiving distance was 15cm, and the precursor was obtained after spinning for 12h. After removing it, it was dried in an oven at 70℃ for 17h.

[0072] (4) The precursor dried in step (3) is pre-sintered at a temperature of 240°C, a holding time of 1.5 h, a heating rate of 5°C / min, and an atmosphere of air.

[0073] (5) The pre-sintered precursor in step (4) was subjected to vacuum filtration. The solvent was a deionized water dispersion of graphene oxide with a concentration of 1 mg / mL. The filtration time was 60 min, and an aqueous filter membrane with a pore size of 0.45 μm was used. The filtered precursor was dried in an oven at 70 °C for 12 h.

[0074] (6) The precursor dried in step (5) is subjected to high-temperature heat treatment at a temperature of 600°C for 4 hours, with a heating rate of 5°C / min and a nitrogen atmosphere. After the high-temperature heat treatment, the desired lithium-ion battery anode material Mo2C / NiO@GO is obtained.

[0075] After phase analysis, the peak values ​​of the lithium battery anode material Mo2C / NiO@GO obtained in this embodiment on XRD are basically consistent with those of the standard, and there are no impurity peaks. It can be determined that the obtained anode material is a composite material of Mo2C and NiO.

[0076] The lithium-ion battery anode material Mo2C / NiO@GO obtained in this embodiment has a uniform morphology and is nanowires with a diameter of 50-150 nm.

[0077] Battery assembly: The same as in Example 1. The constant current charge-discharge performance of the assembled lithium-ion battery was tested at a voltage range of 0 to 3V.

[0078] At a current density of 100 mA / g, the initial discharge specific capacity reached 510.5 mAh / g, and the Coulomb efficiency was stable.

[0079] At a current density of 500 mA / g, its initial reversible discharge specific capacity could still reach 1132 mAh / g. After 180 cycles, its discharge specific capacity could still reach 570.8 mAh / g.

[0080] As can be seen from the above, the lithium-ion battery assembled with the lithium-ion battery anode material Mo2C / NiO@GO obtained in the embodiment of the present invention has a high specific capacity and good cycle stability.

[0081] Example 5

[0082] (1) Weigh 4 mmol of nickel oxide, 1 mmol of ammonium molybdate tetrahydrate, and 9 g of DMF solution and 5 g of DMSO solution, and add them to a beaker in sequence. Seal the bottle mouth with plastic wrap and perform ultrasonic dispersion at a power of 400 W for 60 min;

[0083] (2) Weigh 1.25 g of PVP and add it to the solution ultrasonically dispersed in step (1), stir at 20 °C for 8 h, and the stirring speed is 500 r / min to obtain a spinning solution;

[0084] (3) Use a syringe to suck the spinning solution for electrospinning. The electrospinning voltage is 25 V, the syringe pushing speed is 0.8 mL / h, the receiving distance is 20 cm, and electrospinning for 12 h to obtain a precursor. After taking it down, dry it in an oven at a temperature of 80 °C for 24 h;

[0085] (4) Pre-sinter the precursor dried in step (3). The sintering temperature is 250 °C, the holding time is 1 h, the heating rate is 3 °C / min, and the atmosphere is air;

[0086] (5) Perform suction filtration on the pre-sintered precursor in step (4). The solvent is a graphene oxide deionized water dispersion solution with a dispersion concentration of 0.5 mg / mL. The suction filtration time is 20 min, and a water-based filter membrane with a pore size of 0.45 μm is selected. The precursor after suction filtration is dried in an oven at a temperature of 70 °C for 12 h;

[0087] (6) The precursor dried in step (5) is subjected to high-temperature heat treatment at a temperature of 700℃ for 1 hour, with a heating rate of 2℃ / min and an argon atmosphere. After the high-temperature heat treatment, the desired lithium-ion battery anode material Mo2C / NiO@GO is obtained.

[0088] After phase analysis, the peak values ​​of the lithium battery anode material Mo2C / NiO@GO obtained in this embodiment on XRD are basically consistent with those of the standard, and there are no impurity peaks. It can be determined that the obtained anode material is a composite material of Mo2C and NiO.

[0089] The lithium-ion battery anode material Mo2C / NiO@GO obtained in this embodiment has a uniform morphology and consists of nanowires with a diameter of 50-150 nm.

[0090] Battery assembly: Same as in Example 1. The constant current charge-discharge performance of the assembled lithium-ion battery was tested within a voltage range of 0–3V.

[0091] At a current density of 100 mA / g, the initial discharge capacity can reach as high as 903.7 mAh / g, and the coulombic efficiency is stable.

[0092] At a current density of 500 mA / g, its initial reversible discharge specific capacity can still reach 1125.9 mAh / g, and after 250 cycles, its discharge specific capacity can still reach 725 mAh / g, with a capacity retention rate of 64%.

[0093] As can be seen from the above, the lithium-ion battery assembled with the lithium-ion battery anode material Mo2C / NiO@GO obtained in the embodiments of the present invention has high specific capacity and good cycle stability.

[0094] The lithium-ion battery anode material Mo2C / NiO@GO carbon nanofiber according to an embodiment of the present invention is prepared by the preparation method of the lithium-ion anode material Mo2C / NiO@GO carbon nanofiber according to the above embodiment of the present invention.

[0095] In one example, the Mo2C / NiO@GO carbon nanofiber lithium-ion battery anode material may include: a nano-electrospun film and a graphene coating layer. The nano-electrospun film is composed of a large number of nanofibers (50-300 nm in diameter) woven laterally and longitudinally. The nanofibers uniformly encapsulate Mo2C and NiO nanoparticles, wherein the carbon content of the nanofibers accounts for 20%-40%, and the Mo2C and NiO content accounts for 60%-80%, with a particle size of 10 nm-50 nm.

[0096] Furthermore, the graphene coating is freeze-dried using the Hummer method, with a thickness of 0.335 nm to 1.0 nm and a sheet spacing of 0.2 μm to 10 μm. The graphene coating is then vacuum-filtered to achieve the coating of the electrospun nanofiber membrane with the graphene sheets. Under negative pressure, the graphene sheets penetrate the interwoven gaps of the nanofibers into the interior of the membrane, resulting in a three-dimensional coating. This three-dimensional coating further ensures the stability of the electrochemical performance of the lithium-ion battery anode material.

[0097] In view of this, this invention introduces a composite of highly conductive graphene and two metal compounds, which significantly improves the conductivity of the negative electrode material. Simultaneously, by preparing nanofibers, the lithium-ion diffusion path is shortened, reducing the volume expansion problem during battery charging and discharging. The graphene-coated filaments repeatedly intercalate and deintercalate lithium during cycling, causing a decrease in the crystallinity between graphite layers and exposing more active sites. This not only improves the battery's cycle stability but also continuously increases its charge-discharge specific capacity. Its application and promotion have a positive promoting effect on the preparation and application of high-capacity electrode materials. Therefore, this invention has significant social and economic value.

Claims

1. A method for preparing Mo2C / NiO@GO carbon nanofibers as a lithium-ion battery anode material, characterized in that, Includes the following steps: S1: Weigh out nickel oxide, ammonium molybdate tetrahydrate and solvent, add them to a beaker in sequence, cover with plastic wrap and then perform ultrasonic treatment. The ultrasonic power is 150-550W and the ultrasonic time is 10-120min. The molar ratio of nickel oxide, ammonium molybdate tetrahydrate and solvent is in the range of 1:3 to 1:

1. S2: Weigh the polymeric surfactant and add it to the beaker in step S1. Stir at room temperature to obtain the desired spinning solution. Stir for 8-24 hours at a stirring speed of 100-600 r / min. S3: Electrospinning is performed using a syringe to draw up the spinning solution to obtain the precursor. The spinning voltage is 8-25V, the syringe advance speed is 0.2-1.0mL / h, and the receiving distance is 13-20cm. After spinning is completed, the precursor is removed and dried in an oven at 60-90℃ for 6-24h. S4: The dried precursor from step S3 is pre-sintered at a temperature of 200-250°C for 0.5-2 hours, with a heating rate of 0.5-5°C / min and an air atmosphere. S5: The precursor pre-sintered in step S4 is subjected to vacuum filtration. The solvent is graphene oxide dispersion with a concentration of 0.2-1 mg / mL. The filtration time is 3-60 min. The corresponding membrane material is selected according to the solvent, and the pore size of the filter membrane is less than 1 μm. S6: Next, it is subjected to high-temperature heat treatment at a temperature of 600-900℃, a holding time of 1-5h, a heating rate of 1-5℃ / min, and an inert atmosphere. After the high-temperature heat treatment, the desired lithium-ion battery anode material Mo2C / NiO@GO is obtained.

2. The method for preparing Mo2C / NiO@GO carbon nanofibers, a lithium-ion anode material according to claim 1, is characterized in that, In step S1, the solvent is selected from one or more of the following: N-dimethylformamide (DMF), alcohol, and dimethyl sulfoxide (DMSO).

3. The method for preparing Mo2C / NiO@GO carbon nanofibers, a lithium-ion anode material according to claim 1 or 2, is characterized in that, In step S2, the polymeric surfactant is one of polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), or polyacrylonitrile (PAN).

4. The method for preparing Mo2C / NiO@GO carbon nanofibers, a lithium-ion anode material according to claim 1 or 2, is characterized in that, In step S5, the solvent for the graphene dispersion is one or a mixture of deionized water, N-dimethylformamide (DMF), and alcohol.

5. The method for preparing Mo2C / NiO@GO carbon nanofibers, a lithium-ion anode material according to claim 1 or 2, is characterized in that, The inert gas used in the high-temperature heat treatment in step S6 is either argon or nitrogen, or a mixture of both.

6. A lithium-ion battery anode material, Mo2C / NiO@GO carbon nanofibers, characterized in that, The lithium-ion anode material Mo2C / NiO@GO carbon nanofiber is prepared by the method for preparing lithium-ion anode material Mo2C / NiO@GO carbon nanofiber according to any one of claims 1-5.

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