Lithium electroflexible self-supporting negative material Sn / MoO x @CNFs@rGo and method for preparing the same

Abstract

The application discloses a lithium battery flexible self-supporting negative material Sn / MoO x @CNFs@rGo and a preparation method thereof, the preparation method comprising the following steps: weighing sodium molybdate, stannous chloride dihydrate and a solvent, and adding them into a beaker in sequence, covering the beaker with a preservative film, and then stirring; weighing a high-molecular surfactant, adding the high-molecular surfactant into the beaker, and stirring at 60-80 DEG C to obtain a required spinning solution; electrospinning the spinning solution to obtain a precursor; drying the precursor in an oven; pre-sintering the dried precursor to obtain a spinning film; performing suction filtration on the spinning film as a filter membrane and graphene dispersion liquid as a filtrate to obtain a suction filtration film; and after the suction filtration film is dried, performing heat treatment to obtain the lithium battery flexible self-supporting negative material Sn / MoO x @CNFs@rGo. The lithium battery flexible self-supporting negative material obtained by the method is a pure phase, is in the form of a nanowire coated by graphene, and has a wire diameter of 100-250 nm.

Description

Technical Field

[0001] This invention relates to a method for preparing a battery anode material, specifically a flexible self-supporting lithium-ion battery anode material Sn / MoO. x @CNFs@rGo and its preparation method belong to the field of nanomaterial synthesis and battery preparation. Background Technology

[0002] With the development of today's society and economy, the problem of energy supply imbalance has become increasingly prominent. The development and application of new energy sources and new energy materials has become an important issue. Lithium-ion batteries, as electrochemical power sources, are widely used in mobile phones, laptops, cameras, and other portable electronic devices due to their high capacity, high power density, high safety, and long cycle life. Furthermore, due to their environmentally friendly advantages, they are also used in hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs). Graphite, as the most common commercially available anode material, has a theoretical lithium storage specific capacity of only 372 mAh·g. -1 The efficiency is far below that of applications. Therefore, finding alternative anode materials with better electrochemical performance, such as silicon-based composites, intermetallic compounds, and transition metal oxides, is becoming increasingly important. Among these anode materials, Sn and MoO2... x As a promising candidate material to replace graphite, it has attracted the attention of many scholars. Compared with traditional electrodes, independent electrodes do not require conductive agents, binders, or metal foils. Clearly, using independent, self-supporting electrodes can improve the specific capacity of batteries and reduce costs. More importantly, independent electrodes with excellent mechanical flexibility have broad application prospects for flexible batteries, especially in the field of wearable electronic devices.

[0003] Tin (Sn) anodes have been extensively studied due to their high theoretical capacity (far exceeding that of commercial graphite) and storage mechanism based on reversible lithium alloying / dealloying reactions. However, the lithiation / dealloying process causes Sn volume expansion, gradually leading to electrode pulverization and ultimately rapid degradation of electrode performance, resulting in low capacity and short lifespan. To overcome the pulverization problem of Sn-based materials, mixing them with carbonaceous materials such as carbon nanotubes (CNTs), graphene, and carbon nanofibers (CNFs) is an effective method. These carbon-containing materials not only act as a buffer matrix to mitigate the large changes in Li-Sn alloying / dealloying, but the introduction of metal oxides (Fe3O4, SnO2, MoOx) can also bring additional storage capacity and improve the conductivity of the lithium electrode.

[0004] Therefore, the advantage of this experiment lies in the fact that carbonaceous materials with graphene-coated fibrous structures can shorten the Li-phase insertion / extraction process. +The increased diffusion length is beneficial for improving electrochemical performance. Furthermore, since independent electrodes do not require conductive agents, binders, or metal foils, their use can increase battery capacity and reduce costs. More importantly, independent electrodes, with their excellent mechanical flexibility, have broad application prospects for flexible batteries, especially in the field of wearable electronic devices. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a flexible self-supporting negative electrode material for lithium batteries, Sn / MoOx@CNFs@rGO, and its preparation method.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing Sn / MoOx@CNFs@rGO flexible self-supporting anode material for lithium batteries includes the following steps:

[0008] S1: Weigh a certain amount of sodium molybdate, stannous chloride dihydrate and solvent, add them to a beaker in sequence, cover with plastic wrap, and stir for 1 to 3 hours at a stirring speed of 100 to 800 rpm.

[0009] S2: Weigh a certain amount of polyacrylonitrile and add it to the beaker of S1. Stir at 50-90℃ to obtain the desired spinning solution. Stir for 12-24 hours and at a stirring speed of 100-800 rpm / min.

[0010] S3: Electrospinning is performed using a syringe to draw up the spinning solution. The spinning voltage is 10–25V, the syringe advance speed is 0.3–1.0 mL / h, and the receiving distance is 10–20 cm. After spinning, the precursor is obtained and placed in an oven to dry at 60–90℃ for 6–24 h.

[0011] S4: The dried precursor in S3 is pre-sintered to obtain a spinning film, wherein the sintering temperature is 200-280℃, the holding time is 0.5-3h, the heating rate is 0.5-5℃ / min, and the atmosphere is air.

[0012] S5: The spun membrane in S4 is used as a filter membrane, and the graphene dispersion is used as the filtrate for vacuum filtration to obtain a vacuum filtration membrane. The vacuum filtration time is 1-6 h, and the graphene concentration is 0.1-2 mg / mL.

[0013] S6: After drying the filtration membrane in S5, it undergoes heat treatment at a temperature of 500–1000℃ for 1–4 hours, with a heating rate of 1–10℃ / min, in an inert gas atmosphere. This heat treatment yields the flexible self-supporting lithium-ion battery anode material Sn / MoO. x @CNFs@rGo.

[0014] Preferably, the solvent in step S1 is one or a mixture of three of ethylene glycol methyl ether, N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

[0015] Preferably, the polymeric surfactant in step S2 is one of polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), and polyacrylonitrile (PAN).

[0016] Preferably, the filtration solution used in step S5 is a graphene aqueous dispersion, a graphene DMF dispersion, or a mixture of both.

[0017] Preferably, the inert gas used in the high-temperature heat treatment in step S6 is one of argon and nitrogen, or a mixture of both.

[0018] A flexible self-supporting anode material for lithium batteries, Sn / MoO, prepared using the above method. x @CNFs@rGo.

[0019] Preferably, the lithium-ion battery flexible self-supporting anode material Sn / MoO x @CNFs@rGo refers to graphene-coated carbon nanofibers, which are in the form of nanowires and include a carbon nanofiber layer formed by electrospinning in both the transverse and longitudinal directions.

[0020] MoO x Sn nanoparticles, the MoO x Sn nanoparticles are uniformly encapsulated within the carbon nanofiber layer. Based on the total amount of flexible self-supporting anode material for lithium batteries, MoO... x Sn content is 55%–70%, MoO x Both Sn nanoparticles have a size of 10–50 nm;

[0021] A graphene coating layer, wherein the graphene coating layer is coated on the outside of the carbon nanofiber layer.

[0022] Preferably, in the carbon nanofiber layer, carbon accounts for 30% to 45% of the mass percentage of the carbon nanofiber layer.

[0023] Preferably, the graphene coating is obtained by freeze-drying using the Hummer method, and the thickness of the graphene coating is 0.3 nm-1.0 nm, with a sheet spacing of 0.2-10 μm.

[0024] Preferably, the graphene-coated carbon nanofibers have a wire diameter of 100–250 nm.

[0025] The beneficial effects of the preparation method of the present invention are as follows:

[0026] (1) The Sn / MoO flexible self-supporting negative electrode material for lithium batteries obtained by the method of the present invention x @CNFs@rGo is a pure phase, appearing as nanowires coated with graphene, with a wire diameter of 100–250 nm;

[0027] (2) The method of the present invention has a short process, simple operation, strong controllability, good repeatability, wide applicability, and is suitable for industrial production. In particular, as an independent flexible electrode, it can improve the capacity of the battery and reduce the cost.

[0028] (3) The Sn / MoO flexible self-supporting negative electrode material for lithium batteries obtained by the method of the present invention x @CNFs@rGo can be directly assembled into a lithium-ion battery with a voltage range of 0–3V. At a current density of 0.1A / g, its initial discharge capacity reaches 1322mAh g. -1 The initial charging capacity reaches 1020.5mAh g. -1 It exhibits a first-cycle coulombic efficiency of 77.2% and good rate performance; at a current density of 500 mA / g, its first reversible discharge specific capacity still reaches 742.5 mAh / g, and after 200 cycles, it still retains 618 mAh / g. -1 The reversible capacity and capacity retention rate can reach 83.23%. This demonstrates the effectiveness of the Sn / MoO flexible self-supporting anode material for lithium batteries in this invention. x The batteries assembled by @CNFs@rGo have high specific capacity and good cycle stability, and have significant economic value. Attached Figure Description

[0029] Figure 1 The Sn / MoO flexible self-supporting anode material for lithium batteries obtained in Example 1 of this invention. x @CNFs and Sn / MoO x SEM image of @CNFs@rGo;

[0030] Figure 2 The Sn / MoO flexible self-supporting anode material for lithium batteries obtained in Example 1 of this invention. x XRD and EDS plots of @CNFs@rGo;

[0031] Figure 3 The Sn / MoO flexible self-supporting anode material for lithium batteries obtained in Example 1 of this invention. x The charge / discharge rate performance curve of the lithium-ion battery assembled by @CNFs@rGo;

[0032] Figure 4 The Sn / MoO flexible self-supporting anode material for lithium batteries obtained in Example 1 of this invention. xThe charge-discharge cycle performance curve of the lithium-ion battery assembled by @CNFs@rGo. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings.

[0034] Example 1

[0035] (1) Weigh 5 mmol of sodium molybdate, 1.5 mmol of stannous chloride dihydrate and 12 mL of LDMF, add them to a beaker in sequence, cover with plastic wrap, and stir for 2 hours at a stirring speed of 400 rpm.

[0036] (2) Weigh 1g of polyacrylonitrile and add it to the beaker in (1). Stir at 80℃ for 12h at a stirring speed of 500 rpm to obtain the desired spinning solution.

[0037] (3) Electrospinning was performed by drawing the spinning solution with a syringe. The spinning voltage was 18V, the syringe advance speed was 0.3mL / h, and the receiving distance was 14cm. After spinning, the precursor was obtained and placed in an oven to dry at 80℃ for 12h.

[0038] (4) The dried precursor in (3) is pre-sintered to obtain a spinning film, wherein the sintering temperature is 250℃, the holding time is 2h, the heating rate is 2℃ / min, and the atmosphere is air.

[0039] (5) Use the spinning membrane in (4) as the filter membrane and the graphene aqueous dispersion with a concentration of 1 mg / mL as the filtrate, and filter for 3 hours.

[0040] (6) After the soft film in (5) is dried, it undergoes heat treatment at a temperature of 700℃ for 2 hours, with a heating rate of 8℃ / min and an Ar atmosphere. After the heat treatment, the flexible self-supporting negative electrode material Sn / MoO for lithium batteries is obtained. x @CNFs@rGo.

[0041] A flexible self-supporting anode material for lithium batteries, Sn / MoO, prepared using the above method. x @CNFs@rGo.

[0042] The flexible self-supporting anode material Sn / MoO prepared in Example 1 x @CNFs@rGo performs morphological characterization and electrochemical performance testing:

[0043] in, Figure 1 (a) and (b) represent Sn / MoO₂, respectively. xScanning electron microscope (SEM) images of @CNFs@rGo before and after filtration of graphene oxide. Analysis shows that the nanowire diameter is 170 nm, and the structure of carbon fiber and graphene-coated carbon fiber after filtration was successfully prepared.

[0044] Figure 2 Sn / MoO x The X-ray diffraction and EDS spectra of @CNFs@rGo, compared with the standard PDF card, show complete overlap with elemental Sn. Furthermore, the EDS spectrum displays a Mo peak, indicating successful synthesis of pure-phase Sn / MoO. x @CNFs@rGo;

[0045] Figure 3 , Figure 4 Sn / MoO x @CNFs@rGo is a graph showing the electrochemical performance of a lithium-ion battery, specifically testing the Sn / MoO ratio. x @CNFs@rGo performance multiplier ( Figure 3 ) and cycle performance ( Figure 4 As shown in the figure, the initial discharge capacity reaches 1322 mAh g at a current density of 0.1 A / g. -1 The initial charging capacity reaches 1020.5mAh g. -1 It exhibits a first-cycle coulombic efficiency of 77.2% and good rate performance; at a current density of 500 mA / g, its first reversible discharge specific capacity still reaches 742.5 mAh / g, and after 200 cycles, it still retains 618 mAh / g. -1 It has reversible capacity, with a capacity retention rate of up to 83.23%.

[0046] Example 2

[0047] (1) Weigh 3.5 mmol of sodium molybdate, 1.2 mmol of stannous chloride dihydrate and 14 mL of ethylene glycol methyl ether, add them to a beaker in sequence, cover with plastic wrap, and stir for 3 hours at a stirring speed of 500 rpm.

[0048] (2) Weigh 1.2g of polyacrylonitrile and add it to the beaker in (1). Stir at 70℃ for 16h at a stirring speed of 400 rpm to obtain the desired spinning solution.

[0049] (3) Electrospinning was performed by drawing the spinning solution with a syringe. The spinning voltage was 17V, the syringe advance speed was 0.5mL / h, and the receiving distance was 15cm. After spinning, the precursor was obtained and placed in an oven to dry at 75℃ for 10h.

[0050] (4) The dried precursor in (3) is pre-sintered in air at a temperature of 280℃, a holding time of 1.5h, and a heating rate of 0.5℃ / min.

[0051] (5) Use the spinning membrane in (4) as the filter membrane and the graphene DMF dispersion with a concentration of 0.5 mg / mL as the filtrate, and filter for 4 h.

[0052] (6) After the soft film in (5) is dried, it undergoes heat treatment at a temperature of 600℃ for 3 hours, with a heating rate of 5℃ / min and an atmosphere of N2. After the heat treatment, the flexible self-supporting negative electrode material Sn / MoO for lithium batteries is obtained. x @CNFs@rGo.

[0053] A flexible self-supporting anode material for lithium batteries, Sn / MoO, prepared using the above method. x @CNFs@rGo.

[0054] The flexible self-supporting anode material Sn / MoO prepared in Example 2 x @CNFs@rGo performs morphological characterization and electrochemical performance testing:

[0055] The Sn / MoO flexible self-supporting anode material for lithium batteries obtained in this embodiment x @CNFs@rGo has a uniform morphology and consists of carbon nanowires with a diameter of 100 nm coated with graphene.

[0056] The Sn / MoO flexible self-supporting anode material for lithium batteries obtained in this embodiment x @CNFs@rGo Comparison of diffraction peaks and standard PDF cards revealed complete overlap with elemental Sn, and the EDS spectrum showed a Mo peak, indicating successful synthesis of pure-phase Sn / MoO. x @CNFs@rGo.

[0057] The Sn / MoO flexible self-supporting anode material for lithium batteries obtained in this embodiment x @CNFs@rGo achieved a first discharge capacity of 1260 mAh g at a current density of 0.1 A / g. -1 The initial charging capacity reaches 963.8mAh g. -1 It exhibits a first-cycle coulombic efficiency of 76.5% and good rate performance; at a current density of 500 mA / g, its first reversible discharge specific capacity still reaches 650.5 mAh / g, and after 200 cycles, it still retains 566 mAh / g. -1 It has reversible capacity with a capacity retention rate of up to 87%.

[0058] Example 3

[0059] (1) Weigh 1 mmol of sodium molybdate, 2 mmol of stannous chloride dihydrate and 9 mmol of LDMF-DMSO, add them to a beaker in sequence, cover with plastic wrap, and stir for 1.5 h at a stirring speed of 600 rpm.

[0060] (2) Weigh 0.9g of polyvinylpyrrolidone and add it to the beaker in (1). Stir at 50°C for 18 hours at a stirring speed of 100 rpm to obtain the desired spinning solution.

[0061] (3) Electrospinning was performed by drawing the spinning solution with a syringe. The spinning voltage was 20V, the syringe advance speed was 1mL / h, and the receiving distance was 20cm. After spinning, the precursor was obtained and placed in an oven to dry at 60℃ for 6h.

[0062] (4) The dried precursor in (3) is pre-sintered in air at a temperature of 240℃, a holding time of 0.5h, and a heating rate of 5℃ / min.

[0063] (5) Use the spinning membrane in (4) as the filter membrane and the graphene aqueous dispersion with a concentration of 0.2 mg / mL as the filtrate, and filter for 5 h.

[0064] (6) After the soft film in (5) is dried, it undergoes heat treatment at a temperature of 800℃ for 4 hours, with a heating rate of 3℃ / min and an atmosphere of 50Ar / 50N2. After the heat treatment, the flexible self-supporting negative electrode material Sn / MoO for lithium batteries is obtained. x @CNFs@rGo.

[0065] A flexible self-supporting anode material for lithium batteries, Sn / MoO, prepared using the above method. x @CNFs@rGo.

[0066] The Sn / MoO flexible self-supporting anode material for lithium batteries obtained in this embodiment x @CNFs@rGo has a uniform morphology and consists of carbon nanowires with a diameter of 180 nm coated with graphene.

[0067] The Sn / MoO flexible self-supporting anode material for lithium batteries obtained in this embodiment x @CNFs@rGo Comparison of diffraction peaks and standard PDF cards revealed complete overlap with elemental Sn, and the EDS spectrum showed a Mo peak, indicating successful synthesis of pure-phase Sn / MoO. x @CNFs@rGo.

[0068] The Sn / MoO flexible self-supporting anode material for lithium batteries obtained in this embodiment x @CNFs@rGo achieved a first discharge capacity of 1220 mAh g at a current density of 0.1 A / g.-1 The initial charging capacity reaches 942.8mAh g. -1 It exhibits a first-cycle coulombic efficiency of 77.2% and good rate performance; at a current density of 500 mA / g, its first reversible discharge specific capacity still reaches 635.6 mAh / g, and after 200 cycles, it still retains 540.5 mAh / g. -1 It has reversible capacity and a capacity retention rate of up to 85%.

[0069] Example 4

[0070] (1) Weigh 1.5 mmol of sodium molybdate, 4 mmol of stannous chloride dihydrate and 15 mmol of LDMF-ethylene glycol methyl ether, add them to a beaker in sequence, cover with plastic wrap, stir for 1 hour at a stirring speed of 100 rpm.

[0071] (2) Weigh 1.5g of polyvinyl alcohol and add it to the beaker in (1). Stir at 90℃ for 20h at a stirring speed of 600 rpm to obtain the desired spinning solution.

[0072] (3) Electrospinning was performed by drawing the spinning solution with a syringe. The spinning voltage was 25V, the syringe advance speed was 0.8mL / h, and the receiving distance was 17cm. After spinning, the precursor was obtained and placed in an oven to dry at 85℃ for 16h.

[0073] (4) The dried precursor in (3) is pre-sintered in air at a sintering temperature of 200℃, a holding time of 2.5h, and a heating rate of 1℃ / min.

[0074] (5) Use the spun membrane in (4) as the filter membrane and the graphene water-DMF dispersion with a concentration of 1.2 mg / mL as the filtrate, and filter for 1 h.

[0075] (6) After the soft film in (5) is dried, it undergoes heat treatment at a temperature of 900℃ for 1.5 hours, with a heating rate of 10℃ / min and an atmosphere of 20Ar / 80N2. After the heat treatment, the flexible self-supporting negative electrode material Sn / MoO for lithium batteries is obtained. x @CNFs@rGo.

[0076] A flexible self-supporting anode material for lithium batteries, Sn / MoO, prepared using the above method. x @CNFs@rGo.

[0077] The Sn / MoO flexible self-supporting anode material for lithium batteries obtained in this embodiment x @CNFs@rGo has a uniform morphology and consists of carbon nanowires with a diameter of 220 nm coated with graphene.

[0078] The Sn / MoO flexible self-supporting anode material for lithium batteries obtained in this embodiment x @CNFs@rGo Comparison of diffraction peaks and standard PDF cards revealed complete overlap with elemental Sn, and the EDS spectrum showed a Mo peak, indicating successful synthesis of pure-phase Sn / MoO. x @CNFs@rGo.

[0079] The Sn / MoO flexible self-supporting anode material for lithium batteries obtained in this embodiment x @CNFs@rGo achieved an initial discharge capacity of 1140 mAh g at a current density of 0.1 A / g. -1 The initial charging capacity reaches 988.2mAh g. -1 It exhibits an initial coulombic efficiency of 86.7% and good rate performance; at a current density of 500 mA / g, its initial reversible discharge specific capacity still reaches 580 mAh / g, and after 200 cycles, it still retains 510.6 mAh / g. -1 It has reversible capacity with a capacity retention rate of up to 88%.

[0080] Example 5

[0081] (1) Weigh 2 mmol of sodium molybdate, 3 mmol of stannous chloride dihydrate and 10 mL of DMF-ethylene glycol methyl ether-DMSO, add them to a beaker in sequence, cover with plastic wrap, and stir for 2.5 h at a stirring speed of 800 rpm.

[0082] (2) Weigh 0.6g of polyvinylpyrrolidone and add it to the beaker in (1). Stir at 60°C for 24 hours at a stirring speed of 800 rpm to obtain the desired spinning solution.

[0083] (3) Electrospinning was performed by drawing the spinning solution with a syringe. The spinning voltage was 10V, the syringe feed rate was 0.6mL / h, and the receiving distance was 10cm. After spinning, the precursor was obtained and placed in an oven to dry at 90℃ for 24h.

[0084] (4) The dried precursor in (3) is pre-sintered in air at a sintering temperature of 220℃, a holding time of 3h, and a heating rate of 3℃ / min.

[0085] (5) Use the spinning membrane in (4) as the filter membrane and the graphene water-DMF dispersion with a concentration of 2 mg / mL as the filtrate, and filter for 6 h.

[0086] (6) After the soft film in (5) is dried, it undergoes heat treatment at a temperature of 1000℃ for 1 hour, with a heating rate of 6℃ / min and an atmosphere of 65Ar / 35N2. After the heat treatment, the flexible self-supporting negative electrode material Sn / MoO for lithium batteries is obtained.x @CNFs@rGo.

[0087] A flexible self-supporting anode material for lithium batteries, Sn / MoO, prepared using the above method. x @CNFs@rGo.

[0088] The Sn / MoO flexible self-supporting anode material for lithium batteries obtained in this embodiment x @CNFs@rGo has a uniform morphology and consists of carbon nanowires with a diameter of 250 nm coated with graphene.

[0089] The Sn / MoO flexible self-supporting anode material for lithium batteries obtained in this embodiment x @CNFs@rGo Comparison of diffraction peaks and standard PDF cards revealed complete overlap with elemental Sn, and the EDS spectrum showed a Mo peak, indicating successful synthesis of pure-phase Sn / MoO. x @CNFs@rGo.

[0090] The Sn / MoO flexible self-supporting anode material for lithium batteries obtained in this embodiment x @CNFs@rGo achieved an initial discharge capacity of 1150 mAh g at a current density of 0.1 A / g. -1 The initial charging capacity reaches 920.5mAh g. -1 It exhibits an initial coulombic efficiency of 80% and good rate performance; at a current density of 500 mA / g, its initial reversible discharge specific capacity still reaches 574 mAh / g, and after 200 cycles, it still retains 502.4 mAh / g. -1 It has reversible capacity with a capacity retention rate of up to 87.5%.

[0091] As can be seen from the above, the Sn / MoO flexible self-supporting anode material for lithium batteries obtained in the embodiments of the present invention... x The lithium-ion batteries assembled by @CNFs@rGo have high specific capacity and good cycle stability.

[0092] In summary, the flexible self-supporting anode material Sn / MoOx@CNFs@rGo described in Examples 1-5 is graphene-coated carbon nanofibers. These graphene-coated carbon nanofibers are nanowire-shaped and include...

[0093] A carbon nanofiber layer, which is formed by electrospinning and weaving in both the transverse and longitudinal directions;

[0094] MoO x Sn nanoparticles, the MoO x Sn nanoparticles are uniformly encapsulated within the carbon nanofiber layer. Based on the total amount of flexible self-supporting anode material for lithium batteries, MoO... xSn content is 55%–70%, MoO x Both Sn nanoparticles have a size of 10–50 nm;

[0095] A graphene coating layer, wherein the graphene coating layer is coated on the outside of the carbon nanofiber layer.

[0096] In the carbon nanofiber layer, carbon accounts for 30% to 45% of the mass percentage of the carbon nanofiber layer.

[0097] The graphene coating is obtained by freeze-drying using the Hummer method. The thickness of the graphene coating is 0.3 nm-1.0 nm, and the interlayer spacing is 0.2-10 μm.

[0098] The graphene-coated carbon nanofibers have a wire diameter of 100–250 nm.

[0099] The preparation process provided by this invention is simple, environmentally friendly, highly reproducible, and suitable for industrial production. Its application and promotion will positively contribute to the preparation and application of high-capacity electrode materials. More importantly, the independent electrode with excellent mechanical flexibility has broad application prospects for flexible batteries, especially in the field of wearable electronic devices.

Claims

1. A flexible self-supporting anode material for lithium batteries, Sn / MoO x The preparation method of @CNFs@rGo is characterized by, Includes the following steps: S1: Weigh a certain amount of sodium molybdate, stannous chloride dihydrate and solvent, add them to a beaker in sequence, cover with plastic wrap, and stir for 1-3 hours at a speed of 100-800 rpm. S2: Weigh a certain amount of polymeric surfactant and add it to the beaker in S1. Stir at 60~80 ℃ to obtain the desired spinning solution. The stirring time is 12-24 h and the stirring speed is 100~800 rpm. S3: Electrospinning is performed by drawing the spinning solution obtained in S2 using a syringe. The spinning voltage is 10~25V, the syringe advance speed is 0.3~1.0 mL / h, and the receiving distance is 10~20 cm. After spinning, the precursor is obtained. The precursor is placed in an oven and dried at 60~90℃ for 6~24 h. S4: The dried precursor in S3 is pre-sintered to obtain a spinning film. The sintering temperature is 200~280℃, the holding time is 0.5~3 h, the heating rate is 0.5~5℃ / min, and the atmosphere is air. S5: The spun membrane in S4 is used as a filter membrane, and the graphene dispersion is used as the filtrate for vacuum filtration to obtain a vacuum filtration membrane. The vacuum filtration time is 1-6 h, and the graphene concentration is 0.1-2 mg / mL. S6: After the filtration membrane in S5 is dried, it undergoes heat treatment to obtain the flexible self-supporting negative electrode material Sn / MoO for lithium batteries. x @CNFs@rGo, wherein the heat treatment temperature is 500~1000℃, the holding time is 1~4 h, the heating rate is 1~10℃ / min, and the atmosphere is an inert gas.

2. The Sn / MoO flexible self-supporting negative electrode material for lithium batteries according to claim 1 x The preparation method of @CNFs@rGo is characterized by, The solvent in step S1 is one or a mixture of several of ethylene glycol methyl ether, N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

3. The Sn / MoO flexible self-supporting negative electrode material for lithium batteries according to claim 1 x The preparation method of @CNFs@rGo is characterized by, In step S2, the polymeric surfactant is one of polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), or polyacrylonitrile (PAN).

4. The Sn / MoO flexible self-supporting negative electrode material for lithium batteries according to claim 1 x The preparation method of @CNFs@rGo is characterized by, In step S5, the graphene dispersion is a graphene aqueous dispersion, a graphene DMF dispersion, or a mixture of both.

5. The Sn / MoO flexible self-supporting negative electrode material for lithium batteries according to claim 1 x The preparation method of @CNFs@rGo is characterized by, The inert gas used in the high-temperature heat treatment in step S6 is argon.

6. A flexible self-supporting negative electrode material Sn / MoO according to any one of claims 1-5 x The preparation method of @CNFs@rGo yielded a flexible self-supporting anode material Sn / MoO for lithium batteries. x @CNFs@rGo.

7. The Sn / MoO flexible self-supporting negative electrode material for lithium batteries according to claim 6 x @CNFs@rGo, characterized in that, The flexible self-supporting negative electrode material Sn / MoO for lithium batteries x @CNFs@rGo refers to graphene-coated carbon nanofibers, wherein the graphene-coated carbon nanofibers are in the form of nanowires, and the graphene-coated carbon nanofibers include... A carbon nanofiber layer, which is formed by electrospinning and weaving in both the transverse and longitudinal directions; MoO x Sn nanoparticles, the MoO x Sn nanoparticles are uniformly encapsulated within the carbon nanofiber layer. Based on the total amount of flexible self-supporting anode material for lithium batteries, MoO... x Sn content is 55%–70%, MoO x Both Sn nanoparticles have a size of 10~50 nm; A graphene coating layer, wherein the graphene coating layer is coated on the outside of the carbon nanofiber layer.

8. The flexible self-supporting negative electrode material for lithium batteries according to claim 7, characterized in that, In the carbon nanofiber layer, carbon accounts for 30% to 45% of the mass percentage of the carbon nanofiber layer.

9. The flexible self-supporting negative electrode material for lithium batteries according to claim 7, characterized in that, The thickness of the graphene coating is 0.3nm-1.0nm, and the interlayer spacing is 0.2-10um.

10. The flexible self-supporting negative electrode material for lithium batteries according to claim 7, characterized in that, The graphene-coated carbon nanofibers have a wire diameter of 100–250 nm.

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