CN117457864A

CN117457864A - Antimony-based intermetallic compound/carbon fiber composite material and preparation method thereof

Info

Publication number: CN117457864A
Application number: CN202311327188.6A
Authority: CN
Inventors: 张俊豪; 王喆; 薛凯; 郭兴梅; 郑祥俊; 刘元君
Original assignee: Jiangsu University of Science and Technology
Current assignee: Jiangsu University of Science and Technology
Priority date: 2023-10-13
Filing date: 2023-10-13
Publication date: 2024-01-26

Abstract

The invention discloses an antimony-based intermetallic compound/carbon fiber composite material and a preparation method thereof. The antimony-based intermetallic compound/carbon fiber composite material combines antimony with inactive elements through an electrostatic spinning and high-temperature reduction method, and Sb-based alloy nano particles are successfully dispersed in nitrogen-doped carbon fibers to prepare a series of antimony-based intermetallic compound/carbon nanofiber materials (SbM/CNFs, m=co, zn and Ni). The result shows that SbM/CNF shows excellent sodium storage performance when being used as a negative electrode material of a sodium ion battery. The excellent sodium storage performance is attributed to the synergistic effect of the conductive carbon fibers and SbM nanoparticles, and the electrode material has excellent specific capacity and cycle stability by providing good electrical properties and simultaneously enhancing the structure to reduce volume change. The preparation method is environment-friendly, simple in technological operation, and the product can be prepared in a large scale, thereby being beneficial to industrial production.

Description

Antimony-based intermetallic compound/carbon fiber composite material and preparation method thereof

Technical Field

The invention relates to an antimony-based intermetallic compound/carbon fiber composite material and a preparation method thereof, belonging to the technical field of new materials.

Background

The rapid development of modern society increases the demand for energy, and renewable energy sources such as solar energy, wind energy and the like are receiving great attention. Energy storage technologies can integrate these renewable energy sources into the power grid, and the development of scalable energy storage systems is of great practical importance for reducing the dependence on fossil energy sources. The electrochemical secondary battery has higher energy conversion efficiency and is a promising energy storage technology. Lithium ion batteries are widely used in electric vehicles and portable electronic devices due to their high energy density and long service life. In the periodic table, the sodium element and the lithium element are located in the same main group, and have similar physical/chemical properties. Sodium ion batteries and lithium ion batteries have the same battery assembly and similar energy storage mechanism, except for the different charge transfer modes. Compared with lithium, the sodium resource distribution is wider and richer, and the sodium ion battery has better high-low temperature electrochemical performance and better safety, and has great application potential in fixed and large-scale energy storage systems. Based on larger Na ⁺ The problems of low energy density and poor cycle performance caused by radius have major challenges in developing a high energy density anode material with long cycle life and fast kinetics. Metals (Sn, bi …), metalloids (Si, ge, as, sb …) and polyatomic nonmetallic compounds in group 14 or 15 elements can store large amounts of Na at relatively low operating voltages ⁺ Ions, are potential negative electrode materials. Among them, sb-M binary intermetallic compounds are recently reported as high-performance anode materials. M can be classified into electrochemically inert elements (Ni, cu, fe, zn, co …) and electrochemically active elements (Sn, sb, bi …) according to the (de) alloying reaction with Na. In the electrochemical reaction process, the active element can serve as a buffer when the other party is de-alloyed, so that the stability of the electrode material is maintained and the capacity is improved; the inert element then always acts as a buffer matrix to mitigate volume changes.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a preparation method of an antimony-based intermetallic compound/carbon fiber composite material. SbM nano particles in the composite material are uniformly dispersed in a nitrogen-doped nanofiber conductive carbon network, CNF is used as a buffer substrate to relieve volume expansion and simultaneously provide a transport channel for electrons and ions, so that the conductivity of the electrode is improved, and M is used as a buffer to further relieve volume change in the charge and discharge processes. When used as a negative electrode material of a sodium ion battery, the SbM/CNF composite material shows excellent lithium storage performance.

In order to solve the existing problems, the invention adopts the following technical scheme:

an antimony-based intermetallic compound/carbon fiber composite material is prepared by dissolving antimony acetate, metal nitrate and polyvinylpyrrolidone in a mixed solution of N, N-dimethylformamide and ethanol to obtain a solution A; then preparing the solution A by an electrostatic spinning technology to obtain a SbM/CNF precursor; finally, the SbM/CNF precursor is subjected to pre-oxidation and carbonization treatment to obtain the SbM/CNF composite material.

The preparation method of the antimony-based intermetallic compound/carbon fiber composite material comprises the following steps:

(1) Preparation of SbM/CNF precursor: adding polyvinylpyrrolidone into a mixed solution of N, N-dimethylformamide and ethanol, heating and stirring until the polyvinylpyrrolidone is completely dissolved, and marking the mixture as a solvent A; adding an antimony acetate and a metal nitrate into a solvent A, wherein the mass ratio of the antimony acetate to the metal nitrate is 2:3, and stirring for 12 hours to obtain a uniformly dispersed purple transparent electrostatic spinning solution; after the treatment, collecting the fibers on a collector, and drying the fibers in a vacuum drying oven at 60 ℃ for 12 hours to prepare a SbM/CNF precursor, wherein the ratio of the mass of polyvinylpyrrolidone to the total mass of antimony nitrate and metal nitrate is 1:1, a step of;

(2) Preparation of SbM/CNF composite: and (3) pre-oxidizing the SbM/CNF precursor in a tube furnace, and carbonizing the precursor in an argon atmosphere to obtain the SbM/CNF composite material.

As an improvement, the volume ratio of the N, N-dimethylformamide to the ethanol in the step (1) is 3mL:10mL.

As an improvement, the metal nitrate in step (1) is a transition metal nitrate hexahydrate.

As an improvement, the heating and stirring temperature in the step (1) is 60 ℃, and the stirring time is 10 hours.

As an improvement, the flow rate of the electrostatic spinning solution in the step (1) is 0.4mL h ^-1 The collector was aluminum foil with a receiving distance of 15cm and a 16kV voltage was applied between the electrospinning needle and the collector.

As an improvement, the pre-oxidation in step (2) is carried out at 5 ℃ for min ^-1 The temperature is raised to 250 ℃ and the temperature is kept for 2 hours.

As an improvement, the carbonization in the step (2) is carried out in an argon atmosphere at 2 ℃ for min ^-1 Is heated to 600 ℃ for carbonization for 2 hours.

Design principle

SbM nanometer particles are uniformly dispersed in a nitrogen-doped nanofiber conductive carbon network, and when the carbon nanometer fibers serve as a buffer substrate to relieve volume expansion, a transportation channel is provided for electrons and ions, so that the conductivity of an electrode material is improved, and cobalt serves as a buffer to further relieve volume change in the charge and discharge processes. Therefore, the material used as a negative electrode material of a sodium ion battery exhibits excellent lithium storage performance. The excellent electrochemical performance is attributed to the synergistic effect of the conductive carbon fibers and the SbM nanoparticles, and the electrode material has higher capacity and better stability by providing good electrical properties and enhancing the structure to reduce volume change.

Advantageous effects

Compared with the prior art, the invention combines antimony with inactive elements by an electrostatic spinning and high-temperature reduction method, and successfully disperses the Sb-based intermetallic compound nano particles in the nitrogen-doped carbon fiber to prepare a series of Sb-based intermetallic compound/carbon fiber composite materials (SbM/CNF, M=Co, zn and Ni …). The structure has excellent capability of relieving volume expansion in the charge and discharge process and providing an electron ion transport channel to improve conductivity, and shows higher initial specific capacity and excellent cycle stability. The result shows that SbCo/CNF shows good sodium storage when being used as a negative electrode material of a sodium ion batteryPerformance. At 0.1A g ^-1 The initial discharge specific capacity at the current density of (2) was 604mA h g ^-1 And still has 483.5mA h g after 150 times of circulation ^-1 Is a specific capacity of (a). At a current density of 1A g ^-1 The specific capacity can still be kept at 344.5mA h g after 150 times of circulation ^-1 。

Drawings

FIG. 1 is an SEM image of the product SbCo/CNF prepared in example 1;

FIG. 2 is an SEM image of the product SbZn/CNF prepared in example 2;

FIG. 3 is an SEM image of the product SbNi/CNF prepared in example 3;

FIG. 4 is a TEM image of the product SbCo/CNF prepared in example 1;

FIG. 5 is an XRD spectrum of the products SbCo/CNF, sb/CNF and Co/CNF prepared in example 1, comparative example 2;

FIG. 6 is XRD patterns of the SbZn/CNF and SbNi/CNF products prepared in examples 2 and 3;

FIG. 7 is a thermogravimetric curve of the product SbCo/CNF prepared in example 1;

FIG. 8 is a Raman spectrum of the products SbCo/CNF, sbZn/CNF and SbNi/CNF prepared in examples 1, 2, 3;

FIG. 9 is a XPS survey spectrum of the product SbCo/CNF prepared in example 1;

FIG. 10 is a high-resolution Sb3d spectrum of the product SbCo/CNF prepared in example 1;

FIG. 11 is a Co 2p high resolution spectrum of the product SbCo/CNF prepared in example 1;

FIG. 12 is a C1s high resolution spectrum of the product SbCo/CNF prepared in example 1;

FIG. 13 shows that the product prepared in example 1 has SbCo/CNF at 0.1mV s ^-1 A cyclic voltammogram of sweep rate;

FIG. 14 shows that the product prepared in example 1 has a SbCo/CNF of 0.1. 0.1A g ^-1 A charge-discharge curve at current density;

FIG. 15 shows that the products SbCo/CNF, sb/CNF and Co/CNF prepared in example 1, comparative example 1 and comparative example 2 are in a range of 0.1. 0.1A g ^-1 A graph comparing cycle performance at current density;

FIG. 16 is a graph comparing the rate performance of the products SbCo/CNF, sb/CNF and Co/CNF prepared in example 1, comparative example 1 and comparative example 2 at different current densities;

FIG. 17 shows the products SbCo/CNF, sb/CNF and Co/CNF prepared in example 1, comparative example 2 at 1A g ^-1 A long cycle performance comparison plot at current density;

fig. 18 is a graph of impedance comparison before cycling of the products SbCo/CNF, sb/CNF and Co/CNF prepared in example 1, comparative example 2.

Detailed Description

The following examples will provide those skilled in the art with a more complete understanding of the present invention and are not intended to limit the invention to the embodiments described.

Example 1:

(1) Preparation of SbCo/CNF precursor:

1g of polyvinylpyrrolidone (PVP, mw=130000) was weighed out into a mixed solution of 3mL of N, N-dimethylacetamide and 10mL of ethanol, and heated and stirred at 60℃until completely dissolved. Antimony nitrate and cobalt nitrate hexahydrate were then added in a mass ratio of 2:3. Stirring is continued for 12 hours to obtain the uniformly dispersed electrostatic spinning solution. The obtained purple transparent precursor solution is filled into a plastic injector for electrostatic spinning, and the solution flow rate is set to be 0.4mL h ^-1 The fibers were collected with aluminum foil and the distance between the needle and the fiber collector was kept at 15cm. A voltage of 16kV was applied between the electrospinning needle and the aluminum foil to induce electrospinning. Drying the obtained precursor in a vacuum drying oven at 60 ℃ for 12 hours after spinning is finished, wherein the ratio of the mass of polyvinylpyrrolidone to the total mass of antimony nitrate and metal nitrate is 1:1.

(2) Preparation of SbCo/CNF composite material

Drying the electrostatic spinning precursor in a tube furnace at 5 ℃ for min ^-1 Heating to 250deg.C at a heating rate of 2 hr for pre-oxidation, and then argon (Ar) atmosphere at 2deg.C for 2 min ^-1 Heating to 600 ℃ and carbonizing for 2 hours to obtain the SbCo intermetallic compound/carbon fiber composite material.

FIG. 1 is an SEM image of the product SbCo/CNF prepared in example 1. Can be seen from FIG. 1The diameter of the carbon nanofiber is about 400nm, and the carbon nanofibers are mutually connected to construct a three-dimensional conductive network, so that the three-dimensional conductive network can be used as an electronic path to accelerate charge transfer and improve the conductivity of the electrode. The small amount of dispersed particles on the surface of CNF is Sb generated in the high-temperature reduction process ₂ O ₃ 。

FIG. 4 is a TEM spectrum of the product SbCo/CNF prepared in example 1. From fig. 4, it can be seen that SbCo nanoparticles with a diameter of 30nm are uniformly dispersed in the whole carbon fiber, and the carbon fiber can effectively adapt to the large volume expansion of Sb in the sodiumizing process as a buffer matrix, so as to improve the stability of the electrode material, and it can also be observed that a certain gap exists between each nanoparticle, so that the mechanical stress in the alloying/dealloying process can be effectively released.

FIG. 7 is a thermogravimetric curve of the product SbCo/CNF prepared in example 1. From fig. 7, it can be observed that the curve has a weight loss of 3.099% in the range of 0-110 ℃ due to volatilization of the moisture absorbed by the sample during storage. At 110-300 ℃, sbCo is generated by oxidation reaction ₃ O ₄ And Sb (Sb) ₂ O ₃ Resulting in a weight gain of about 4.6%. As the temperature continues to rise, in the interval 300 to 400 ℃, the decomposition of the carbon substrate due to exposure to air causes a sharp weight loss of the composite. At 400-600 ℃, sb ₂ O ₃ Conversion to Sb ₂ O ₄ Resulting in a slight increase in weight (Sb ₂ O ₃ +1/2O ₂ ＝Sb ₂ O ₄ ) When the temperature reaches 650 ℃, sb ₂ O ₃ Complete conversion to Sb ₂ O ₄ A stable platform appears. The content of SbCo in the sample was calculated to be 69.12wt%.

Fig. 8 is a raman spectrum of the product SbCo/CNF prepared in example 1. From FIG. 8, it can be seen that at 1365cm ^-1 And 1598cm ^-1 Two broad peaks appear at the positions corresponding to the D band and G band, respectively, the intensity ratio of the D band and the G band of SbCo/CNF (I _D /I _G ) 1.22 shows that the carbon nanofibers have a higher degree of disorder of the carbon and a rich defect in the carbon network, which helps to strengthen Na ⁺ Thereby improving the electrochemical performance of the SIB.

FIG. 9 is a XPS full spectrum of the product SbCo/CNF prepared in example 1. Characteristic peaks of C, sb, co, N and O can be observed from fig. 9.

Fig. 10 is a Sb3d high resolution spectrum of the product SbCo/CNF prepared in example 1. The Sb3d high resolution spectrum is fitted to five independent peaks, containing data from Sb3d _3/2 And Sb3d _5/2 Of the two sets of spin orbitals of (a), located at 537.18eV (Sb 3d _3/2 ) And 527.58eV (Sb 3 d) _5/2 ) The characteristic peaks at these correspond to Sb0 in the metal Sb and SbCo alloys, respectively. Peaks at 530.8 and 539.7eV are attributed to Sb ₂ O ₃ Sb in (b) ³⁺ At the same time a low intensity O1s peak was observed at 532.38eV, indicating that the sample was partially oxidized during the preparation.

FIG. 11 is a Co 2p high resolution spectrum of the product SbCo/CNF prepared in example 1. The high resolution Co 2p spectrum has six distinct peaks, characteristic peaks at 797.08eV and 780.78eV correspond to Co 2p of Co-O, respectively _3/2 And Co 2p _1/2 A track. The two peaks at 792.78 and 777.78eV correspond to Co 2p of SbCo alloy, respectively _3/2 And Co 2p _1/2 The characteristic peaks at 802.58eV and 787.28eV are satellite peaks in orbit.

FIG. 12 is a C1s high resolution spectrum of the product SbCo/CNF prepared in example 1. The high resolution XPS spectra of SbCo/CNF composite C1s were fitted to three peaks at 288.78, 286.08 and 284.58eV, corresponding to C-N, C = N and C-C bonds, respectively, indicating that the N atom was successfully doped. N doping can not only improve the conductivity of the carbon substrate, but also be Na ⁺ Insertion provides an active site, thereby enhancing the sodium storage capacity of the material.

FIG. 13 shows that the product prepared in example 1 has SbCo/CNF at 0.1mV s ^-1 Cyclic voltammogram of sweep rate. From fig. 13, it can be seen that the reduction peaks at 0.7V and 0.38V are observed in the first cathode scan, with higher intensity than the latter several cycles due to the alloying reaction of Sb and the formation of a Solid Electrolyte Interphase (SEI) film. In the subsequent cycles, the reduction peaks stabilize at 0.41V and 0.48V, corresponding to the Sb first forming NaSb, the final sodiumized product being Na ₃ Stepwise alloying reaction of Sb. In anodic scan, the peak at 0.82V is attributed to the ion flux from Na ₃ Reversible dealloying of Sb to intermediate NaSb to final regenerated Sb. In the subsequent 2-4 scans, the overlap of cyclic voltammograms was good, indicating that the electrochemical reversibility and cyclic stability of the SbCo/CNF composite were better.

FIG. 14 shows that the product prepared in example 1 has a SbCo/CNF of 0.1. 0.1A g ^-1 Charge-discharge curve at current density. From fig. 14, it can be seen that two discharge platforms appear at 0.8V and 0.5V, corresponding to irreversible formation of SEI film on the surface of SbCo/CNF anode material during the first cycle. The plateau stabilized at 0.4V and about 0.9V in the subsequent charge and discharge processes corresponds to the alloying and dealloying reaction processes of na—sb, respectively, corresponding to the results of the cyclic voltammogram test. The first discharge capacity of the SbCo/CNF electrode material is 604mA h g ^-1 The charging capacity is 560mA h g ^-1 The initial coulombic efficiency was 93.7%, and the capacity loss was attributed to a partially irreversible sodium modification/removal process and SEI film generation.

Example 2:

the difference from example 1 is that zinc nitrate hexahydrate was used instead of cobalt nitrate hexahydrate to prepare a material, which was designated as example 2.

FIG. 2 is an SEM image of the product SbZn/CNF prepared in example 2. As can be seen from FIG. 2, the SbZn/CNF prepared by the method has similar morphology with the SbCo/CNF prepared by the same method, which shows that the method can be applied to the same type of transition metal elements to prepare the Sb-based intermetallic compound with the same morphology, thus showing that the preparation method of the invention has certain universality.

FIG. 6 is an XRD spectrum of the product SbZn/CNF prepared in example 2. From fig. 6, it is clearly observed that three broad peaks at 31.77 °, 44.54 ° and 46.53 °, corresponding to the (101), (102) and (110) crystal planes of hexagonal NiSb (JCPDS No. 75-0604), exist around 24 °, the broad peaks of carbon generated by PVP pyrolysis.

FIG. 8 is a Raman spectrum of the product SbZn/CNF prepared in example 2. From FIG. 8, it can be seen that at 1365cm ^-1 And 1598cm ^-1 Two broad peaks appear at the locations corresponding to the D and G bands, respectively, the intensity ratios of the D and G bands of SbNi/CNF (I _D /I _G ) The number of the groups was 1.08,indicating that the carbon nano-fiber has higher disorder degree of carbon and rich defects in the carbon network.

The SbZn/CNF composite material also exhibits excellent performance as a sodium ion battery anode material, but its cycle performance and rate performance are slightly inferior to that of the SbCo/CNF composite material, mainly due to the fact that part of zinc is evaporated at high temperature calcination.

Example 3:

the difference from example 1 is that nickel nitrate hexahydrate was used instead of cobalt nitrate hexahydrate to prepare a material, which was designated as example 3.

FIG. 3 is an SEM image of the product SbNi/CNF prepared in example 3. As can be seen from FIG. 3, the SbNi/CNF prepared by the method has similar morphology with the SbCo/CNF prepared by the same method, which shows that the method can be applied to the same type of transition metal elements to prepare the Sb-based intermetallic compound with the same morphology, thus showing that the method has certain universality.

FIG. 6 is an XRD spectrum of the product SbNi/CNF prepared in example 3. The characteristic peaks that can be observed at 44.14 °,46.03 ° from fig. 6 correspond to the (132) and (213) crystal planes of SbZn (JCPDS No. 05-0714), with a broad carbon peak produced by PVP pyrolysis near 24 °.

FIG. 8 is a Raman spectrum of the product SbNi/CNF prepared in example 3. From FIG. 8, it can be seen that at 1365cm ^-1 And 1598cm ^-1 Two broad peaks appear at the locations corresponding to the D and G bands, respectively, the intensity ratios of the D and G bands of SbZn/CNF (I _D /I _G ) 1.16, showing a high degree of disorder of the carbon in the carbon nanofibers and a rich defect in the carbon network.

The SbNi/CNF composite material also shows excellent performance as a negative electrode material of a sodium ion battery, but has slightly poorer cycle performance than the SbCo/CNF composite material, which is mainly due to poorer capacity of nickel to replace cobalt to buffer volume expansion.

Example 4:

the difference from example 1 is that the calcination temperature used to prepare the SbCo/CNF composite was 500℃and the material prepared was designated example 4.

XRD spectrum results show that SbCo-Si compounds are formed in the SbCo/CNF composite material calcined at 500 ℃, but the crystallinity of the carbon fiber is lower, and Raman spectrum also shows the result. The sodium storage performance result shows that compared with the SbCo/CNF composite material prepared by calcining at 600 ℃, the SbCo/CNF composite material prepared by calcining at 600 ℃ has slightly poorer multiplying power performance, which is mainly attributed to poor conductivity caused by low crystallinity of the carbon fiber.

Example 5:

the difference from example 1 is that the calcination temperature used to prepare the SbCo/CNF composite was 700℃and the material prepared was designated example 5.

XRD spectrogram results show that the SbCo/CNF composite material prepared by calcining at 700 ℃ has high crystallinity, and the result is also proved by Raman spectrograms, wherein the SbCo/CNF composite material comprises SbCo and CNF; however, the nitrogen adsorption and desorption results show that the specific surface area of the SbCo/CNF composite material is smaller. The sodium storage performance result shows that compared with the SbCo/CNF composite material prepared by calcining at 600 ℃, the SbCo/CNF composite material prepared by calcining at 700 ℃ has lower specific capacity.

Comparative example 1:

the difference from example 1 is that antimony acetate alone is used to prepare the Sb/CNF composite material, and the prepared material is designated as comparative example 1.

The results show that when antimony acetate alone is used, the morphology and structure are similar to those of the SbCo/CNF composite material in example 1, but the rate capability is poor, which is mainly due to the poor capability of relieving volume expansion of the Sb/CNF composite material caused by the lack of Co.

Comparative example 2

The difference from example 1 is that the SbCo/CNF composite material was prepared using only metal nitrate, and the prepared material was designated as comparative example 2.

FIG. 5 is an XRD spectrum of Co/CNF as the product prepared in comparative example 2. From fig. 5 it can be observed that there is a broad peak around 26 ° corresponding to amorphous carbon produced by PVP decomposition. Since the elements of all samples are dispersed within the carbon fiber, the characteristic peak intensities of Co, sb, and SbCo are relatively low. Characteristic peaks of SbCo/CNF appearing at 31.58 °, 44.03 °, 46.6 °, 57.94 ° and 59.68 ° correspond to (101), (102), (110), (201) and (112) crystal planes of crystalline SbCo (JCPDS No. 33-0097), respectively, and no characteristic peaks corresponding to Sb and Co are observed therein, indicating that Sb, co in the sample have been converted to SbCo and have good crystallinity.

FIG. 15 shows that the products SbCo/CNF, sb/CNF and Co/CNF prepared in comparative example 2 were in a range of 0.1A g ^-1 Comparison of cycle performance at current density. The electrochemical performance test is carried out by assembling CR2032 type half-cell, firstly weighing and mixing Co/CNF, carbon black and carboxymethyl cellulose according to the mass ratio of 7:1.5:1.5, grinding for 30min, adding a proper amount of deionized water, stirring for 12h to form uniform electrode slurry, coating the prepared slurry on copper foil by using a tetragonal preparation device, pre-drying at 25 ℃ for 30min, drying at 70 ℃ in a vacuum drying box for 12h, slicing into wafers with the diameter of 12nm, taking sodium sheets and glass fiber filter paper as counter electrodes and diaphragms respectively, and preparing the electrode slurry with the concentration of 1.0mol L ^-1 NaPF of (a) ₆ Propylene carbonate dissolved in 100vol% is used as electrolyte, and the battery is assembled in a glove box filled with argon, wherein the concentration of water and oxygen is lower than 0.1ppm; constant current discharge-charge cycle testing was done on a blue electric test system (LAND CT 2001A), with a voltage range of 0.01-3V. From fig. 15, it can be seen that all three materials exhibited good stability due to the buffering effect of the carbon nanofibers. Initial capacities of SbCo/CNF, sb/CNF and Co/CNF cathodes were 580, 458 and 403mA h g, respectively ^-1 The specific capacity after 100 cycles can be maintained at 483, 367.9 and 300mA h g ^-1 The capacity retention was 83.2%, 80.3% and 74%, respectively. Compared with Sb/CNF and Co/CNF cathodes, the SbCo/CNF cathode has better reversible specific capacity and cycle stability, which indicates that the inert Co element can enhance the structure to reduce the volume change while providing good electrical property, so that the electrode material has higher capacity and stability.

Fig. 16 is a graph comparing the rate performance of the products SbCo/CNF, sb/CNF and Co/CNF prepared in comparative example 2 at different current densities. The rate performance test was completed on a blue electric test system (LAND CT 2001A) with a voltage range of 0.01-3V. As can be seen from FIG. 16, the charge-discharge specific capacities of the SbCo/CNF negative electrode under the corresponding current densities are 537.8, 477.5, 423.4, 339.3, 299.1mA h g, respectively ^-1 When the current is denseDegree back to 0.1A g ^-1 When the specific capacity is recovered to 469mA h g ^-1 The capacity retention rate reaches 87%. The high capacity retention indicates that the SbCo/CNF composite material has good rate capability, while the specific capacities of Sb/CNF and Co/CNF are lower but still have higher capacity retention.

FIG. 17 shows the products SbCo/CNF, sb/CNF and Co/CNF prepared in comparative example 2 at 1A g ^-1 Long cycle performance at current density versus graph. The cyclic voltammetry curve test is completed by using a Chenhua workstation (CHI 760E), the voltage window is 0.01-2V, and the sweeping speed is 0.1-1mV s ^-1 . From FIG. 17, it can be seen that the cycle performance of the material is equal to or higher than 0.1. 0.1A g ^-1 The performances are basically consistent, the SbCo/CNF negative electrode has higher specific charge-discharge capacity and better stability, and the specific discharge capacity after the 2 nd circle and the 200 th circle are 384 and 344.9mA h g respectively ^-1 The capacity retention was 89.6%.

Fig. 18 is a graph of impedance contrast before cycling of the products SbCo/CNF, sb/CNF and Co/CNF prepared in comparative example 2. Electrochemical Impedance (EIS) is accomplished using Chenhua workstation (CHI 760E) with EIS frequency in the range of 0.1-100kHz. From fig. 18, it can be known that the nyquist curve is composed of a semicircle and an oblique line in a low frequency region, and corresponds to a charge transfer resistor (Rct) and a Warburg impedance (W), and after the Zview software is fitted to the equivalent circuit, the Rct value of the SbCo/CNF composite material is 311.1 Ω, which is lower than Sb/CNF (457.9 Ω) and Co/CNF (389.8 Ω), which indicates that the introduction of Co element can improve the conductivity of the electrode material, so that the alloying and dealloying processes can be successfully completed, and meanwhile, the ion diffusion capability and the electron conductivity are increased, and the electron/ion transmission capability is improved.

The results show that when the mass ratio of antimony acetate to metal nitrate is 0:1, the morphology and structure of the Co/CNF composite material are similar to those of the SbCo/CNF composite material in example 1, but the specific capacity is poor.

The foregoing has shown and described the basic principles and main features of the present invention and the advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. An antimony-based intermetallic compound/carbon fiber composite material is characterized in that a solution A is prepared by dissolving antimony acetate, metal nitrate and polyvinylpyrrolidone in a mixed solution of N, N-dimethylformamide and ethanol; then preparing the solution A by an electrostatic spinning technology to obtain a SbM/CNF precursor; finally, the SbM/CNF precursor is subjected to pre-oxidation and carbonization treatment to obtain the SbM/CNF composite material.

2. A method for preparing an antimony-based intermetallic compound/carbon fiber composite material according to claim 1, comprising the steps of:

(1) Preparation of SbM/CNF precursor: adding polyvinylpyrrolidone into a mixed solution of N, N-dimethylformamide and ethanol, heating and stirring until the polyvinylpyrrolidone is completely dissolved, and marking the mixture as a solvent A; adding an antimony acetate and a metal nitrate into a solvent A, wherein the mass ratio of the antimony acetate to the metal nitrate is 2:3, and stirring for 12 hours to obtain a uniformly dispersed purple transparent electrostatic spinning solution; after collecting the fibers on a collector after treatment, drying in a vacuum drying oven at 60 ℃ for 12 hours to prepare SbM/CNF precursor, wherein the ratio of the mass of polyvinylpyrrolidone to the total mass of antimony nitrate and metal nitrate is 1:1, a step of;

3. The method for preparing an antimony-based intermetallic compound/carbon fiber composite material according to claim 2, wherein the volume ratio of N, N-dimethylformamide to ethanol in the step (1) is 3mL:10mL.

4. The method of preparing an antimony-based intermetallic compound/carbon fiber composite material according to claim 2, wherein the metal nitrate in step (1) is a transition metal nitrate hexahydrate.

5. The method for producing an antimony-based intermetallic compound/carbon fiber composite material according to claim 2, wherein the heating and stirring temperature in the step (1) is 60 ℃ and the stirring time is 10 hours.

6. The method for preparing an antimony-based intermetallic compound/carbon fiber composite material according to claim 2, wherein the flow rate of the electrospinning solution in the step (1) is 0.4mL h ^-1 The collector was aluminum foil with a receiving distance of 15cm and a 16kV voltage was applied between the electrospinning needle and the collector.

7. The method for producing an antimony-based intermetallic compound/carbon fiber composite material according to claim 2, wherein the pre-oxidation in step (2) is carried out at 5℃for min ^-1 The temperature is raised to 250 ℃ and the temperature is kept for 2 hours.

8. The method for producing an antimony-based intermetallic compound/carbon fiber composite material according to claim 2, wherein the carbonization in step (2) is performed in an argon atmosphere at 2℃for a period of 2 ℃ ^-1 Is heated to 600 ℃ for carbonization for 2 hours.