CN110085441A - A kind of Cu-Ag/ carbon nano-fiber composite material and its preparation method and application - Google Patents

Abstract

The present invention prepares Cu-Ag/carbon nanofiber composite material through carbonization again with electrospinning method, and the Cu-Ag/CNF composite material that the inventive method makes has higher specific surface area and electrical conductivity, and higher ratio The surface area can generate more active sites to make it easier for electrons or ions to transfer. When applied to the anode material of a supercapacitor, it can effectively generate an electrode material with a large specific capacitance, good cycle performance, long life, and low pollution. This is because The metal Cu and Ag supported on the carbon fiber help to improve the electrode conductivity, improve the Coulombic efficiency, and finally improve the cycle performance of the electrode to a certain extent; and optimize the process reaction conditions, greatly simplify the synthesis process and reduce the cost.

Description

A kind of Cu-Ag/carbon nanofiber composite material and its preparation method and application

technical field

The invention relates to the field of carbon fibers, in particular to a Cu-Ag/carbon nanofiber composite material and its preparation method and application.

Background technique

Carbon-based materials have been widely used in various forms of supercapacitor electrode materials, although carbon-based electrodes have excellent cycle stability, long life and high power density, compared with metal oxides, the specific capacitance of carbon-based electrodes is usually Although the application of metal oxides on supercapacitor electrodes has certain advantages, especially its high theoretical specific capacitance, there are still some shortcomings, such as low conductivity and volume changes during charging and discharging. The deficiency usually leads to poor rate performance and long-term stability of the electrode, which limits its practical application in supercapacitors; therefore, combining carbon-based materials with metal particles to form composite electrodes is an important research direction.

According to the search of the existing technology, it was found that the two-step method of electrospinning and hydrothermal treatment used in "Preparation of C@MnO ₂ Composite Materials and Research on Supercapacitive Performance" published by Xu Jiren, CNF was prepared by electrospinning, and then passed through water The thermal method loads MnO ₂ on CNF, but this method is easy to introduce impurities in the preparation process, and the operation is complicated, and it is not easy to realize industrialization; "Fabrication of Cu ₂ O/Ag composite nanoframes as surface-enhanced Raman scattering" published by Lihua Yang Substrates in a successful one-pot procedure", the final product contains metal oxides, which leads to low conductivity and poor cycle stability.

At present, the carrier of electrode materials is mainly carbon black, and nano-carbon materials are constantly being studied due to their good electrical and thermal properties. As a new type of carbon material, nano-carbon fibers have a variety of superior physical and chemical properties. It is a new type of material with good application prospects. At present, there are very few studies on the study of nanometer metal particles Cu and Ag loaded on carbon nanofibers as electrode materials for supercapacitors.

SUMMARY OF THE INVENTION

In order to solve the technical problems of low specific capacitance and poor cycle performance when carbon nanofibers are used as carbon-based electrodes, a Cu-Ag/carbon nanofiber composite material and its preparation method and application are provided.

The present invention is realized through the following technical solutions:

A Cu-Ag/carbon nanofiber composite material, wherein metal elemental copper and silver are loaded on carbon nanofibers, and the loading weight percents of the metal elemental copper and silver are 17%-29% and 30%-58% respectively.

The preparation method of the above-mentioned Cu-Ag/carbon nanofiber composite material comprises the following steps:

(1) Preparation of spinning solution: dissolve polyacrylonitrile in a good solvent, stir well to obtain solution A; pour copper salt into solution A, stir at room temperature to obtain mixed solution B; pour silver salt into mixed solution B , stirred at room temperature to obtain a mixed solution C;

(2) Preparation of the precursor: the mixed solution C is electrospun, and after the electrospinning is completed, it is dried at room temperature to prepare the precursor Cu-Ag/PAN nanofiber;

(3) Preparation of Cu-Ag/carbon nanofiber composite material: the precursor obtained in step (2) was calcined under inert gas to prepare Cu-Ag/carbon nanofiber composite material (Cu-Ag/CNF).

Further, the good solvent described in step (1) is N,N-dimethylformamide.

Further, the copper salt described in step (1) is copper acetate, copper chloride or copper nitrate.

Further, the silver salt described in step (1) is silver acetate, silver chloride or silver nitrate.

Further, the mass ratio of copper salt, silver salt and polyacrylonitrile in step (1) is 1:1:(0.1-5).

Preferably, the mass ratio of copper salt, silver salt and polyacrylonitrile in step (1) is 1:1:(0.5-5).

Further, the electrospinning in step (2) is carried out at a voltage of 10-20 kV, a flow rate of 0.8-2 mL/h, and a height of 10-20 cm.

Further, the calcination in step (3) is carried out at a temperature of 450-700° C. and a time of 2-5 hours.

Further, the inert gas in step (3) is _N2 or Ar.

The invention also provides an application of the Cu-Ag/carbon nanofiber composite material on the anode material of the supercapacitor.

It should be noted that in the precursor Cu-Ag/PAN, Cu and Ag are not the metal element copper and silver in the final product, and the symbols Cu and Ag only express the existence of copper and silver elements in the precursor; while the final product Cu -In Ag/CNF, Cu and Ag exist in the form of metal elements, and the symbols Cu and Ag are the chemical expressions of metal elements copper and silver.

After a lot of experiments, it is found that if the mass ratio of copper salt, silver salt and polyacrylonitrile is 1:1:x, when x<0.2, the prepared sample cannot be completely filamentous, and other impurities will be produced; when When x>3, the synthetic nanofibers are easy to agglomerate together; if the voltage is lower than 10kv in step (2), the flow rate is higher than 2mL/h, and the height is higher than 20cm, the sample ejected is subjected to the effect of electric field force and becomes smaller, cannot Completely filamentous, accompanied by solution dripping; if the voltage in step (2) is higher than 20kv, the flow rate is lower than 1mL/h, and the height is lower than 15cm, electric sparks will be generated, which is more dangerous; if calcined in step (3), If the temperature is lower than 450°C or the calcination time is less than 2h, the carbonization of the sample is incomplete and accompanied by impurities such as CuO; if the calcination temperature in step (3) is higher than 700°C or the calcination time is longer than 5h, the distribution of Cu and Ag particles will be uneven , a reunion occurs.

The beneficial effect of the present invention is: the present invention prepares Cu-Ag/carbon nanofiber composite material through electrospinning method again through carbonization, and the Cu-Ag/CNF composite material that the inventive method makes has higher specific surface area and Conductivity, a higher specific surface area can generate more active sites to enable easier transfer of electrons or ions. When applied to the anode material of a supercapacitor, it can effectively generate a large specific capacitance, good cycle performance, long life, and low pollution. This is because the metal Cu and Ag loaded on the carbon fiber help to improve the electrode conductivity to a certain extent, improve the Coulombic efficiency, and finally improve the cycle performance of the electrode; and optimize the process reaction conditions, greatly simplifying the Synthetic process and reduced cost.

Description of drawings

FIG. 1 is an XRD pattern of the Cu-Ag/PAN precursor prepared in Example 1.

FIG. 2 is a SEM topography diagram of the Cu-Ag/PAN precursor prepared in Example 1.

FIG. 3 is an XRD pattern of Cu-Ag/CNF prepared in Example 1.

FIG. 4 is a SEM topography diagram of Cu-Ag/CNF prepared in Example 1.

Fig. 5 is that the Cu/CNF that comparative example 1 makes, the Ag/CNF that comparative example 2 makes, the Cu-CuO/CNF that comparative example 3 makes and the Cu-Ag/CNF that embodiment 1 makes are applied to supercapacitor The specific capacitance data graph measured when the anode material is used.

Fig. 6 is that the Cu/CNF that comparative example 1 makes, the Ag/CNF that comparative example 2 makes, the Cu-CuO/CNF that comparative example 3 makes and the Cu-Ag/CNF that embodiment 1 makes are applied to supercapacitor The measured cycle performance data graph of the anode material.

Detailed ways

The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but the scope of the present invention is not limited.

Example 1

The preparation method of Cu-Ag/carbon nanofiber composite material comprises the following steps:

(1) Preparation of spinning solution: Weigh 1.102g of polyacrylonitrile and dissolve it in 12mL of N,N-dimethylformamide solvent, stir well to obtain solution A; weigh 1.332g of copper acetate and pour it into solution A , stirred at room temperature for 3 hours to obtain a mixed solution B; weighed 1.331 g of silver acetate and poured it into the mixed solution B, and stirred at room temperature for 2 hours to obtain a mixed solution C;

(2) Preparation of the precursor: place the mixed solution C in the syringe, and perform electrospinning at a voltage of 15kV, a flow rate of 1mL/h and a height of 15cm. After the electrospinning is completed, dry at room temperature overnight. Precursor Cu-Ag/PAN nanofibers were prepared;

(3) Preparation of Cu-Ag/carbon nanofiber composite material: the precursor obtained in step (2) was placed in a porcelain boat, and heated from room temperature to 450 °C at a rate of 5 °C/min under the condition of passing _N2 , and calcined for 2.3h to prepare the sample Cu-Ag/CNF.

Calculate the theoretical loading (theoretical mass percentage of substances contained in the product): the loading of Cu is 20.73%, and the loading of Ag is 42.11%.

Carry out X-ray diffraction to the precursor Cu-Ag/PAN nanofiber of the step (2) that the present embodiment makes, gained XRD spectrogram is shown in Figure 1, contrast standard card, the structure of precursor Cu-Ag/PAN The diffraction peaks of C and Ag appear in the phase diagram, which are 23.3°, 38.3°, 44.5°, 64.9°, 77.8°, 81.8°, respectively.

The precursor Cu-Ag/PAN of the step (2) prepared in this embodiment is observed by a scanning electron microscope, and the resulting SEM topography is shown in Figure 2, as can be seen from Figure 2, the present invention's embodiment 1 The prepared precursor Cu-Ag/PAN nanofibers are in the shape of bead chains, and Cu and Ag are jointly loaded on the PAN fibers in a bead-like structure.

Carry out X-ray diffraction to the product Cu-Ag/CNF that the present embodiment makes, the obtained XRD spectrogram is as shown in Figure 3, compares the standard card, as can be seen from Figure 3, after carbonization, at 38.7 °, 43.8 °, 45 ° , 51°, 64.9°, 74.5°, 77.8°, 81.8° have diffraction peaks corresponding to Cu and Ag.

The Cu-Ag/CNF prepared in this example was observed with a scanning electron microscope, and the obtained SEM topography is shown in Figure 4. It can be seen from Figure 4 that the Cu-Ag/CNF composite material is also in the shape of a bead chain, And the diameter of the carbon fiber monofilament is about 1 micron, and the metal Cu and Ag particles are evenly and tightly loaded on the surface of the CNF.

The specific surface area and electrical conductivity of the Cu-Ag/CNF prepared in this implementation were tested, and the test results are shown in Table 1.

Example 2

The preparation method of Cu-Ag/carbon nanofiber composite material comprises the following steps:

(1) Preparation of spinning solution: Weigh 0.302g of polyacrylonitrile and dissolve it in 12mL of N,N-dimethylformamide solvent, stir well to obtain solution A; weigh 1.331g of copper acetate and pour it into solution A , stirred at room temperature for 3 hours to obtain a mixed solution B; weighed 1.332 g of silver acetate and poured it into the mixed solution B, stirred at room temperature for 2 hours to obtain a mixed solution C;

(2) Preparation of the precursor: place the mixed solution C in the syringe, and perform electrospinning at a voltage of 15kV, a flow rate of 1mL/h and a height of 20cm. After the electrospinning is completed, dry at room temperature overnight. Prepare Cu-Ag/PAN nanofibers;

(3) Preparation of Cu-Ag/carbon nanofiber composite material: place the nanofibers obtained in step (2) in a porcelain boat, and heat it from room temperature to 600°C at a rate of 5°C/min under the condition of passing _N2 , and calcined for 2h to prepare the sample Cu-Ag/CNF.

Calculate the theoretical loading (theoretical mass percentage of substances contained in the product): the loading of Cu is 28.46%, and the loading of Ag is 57.85%.

The specific surface area and electrical conductivity of the composite material prepared in this example were tested, and the measured specific surface area was 640 m ² /g, and the electrical conductivity was 19.1 S/cm.

Example 3

The preparation method of Cu-Ag/carbon nanofiber composite material comprises the following steps:

(1) Preparation of spinning solution: Weigh 0.801g of polyacrylonitrile and dissolve it in 12mL of N,N-dimethylformamide solvent, stir well to obtain solution A; weigh 1.332g of copper acetate and pour it into solution A , stirred at room temperature for 3 hours to obtain a mixed solution B; weighed 1.335 g of silver acetate and poured it into the mixed solution B, and stirred at room temperature for 3.5 hours to obtain a mixed solution C;

(2) Preparation of the precursor: place the mixed solution C in the syringe, and perform electrospinning at a voltage of 20kV, a flow rate of 0.8mL/h and a height of 10cm, and dry overnight at room temperature after electrospinning , making Cu/PAN nanofibers;

(3) Preparation of Cu-Ag/carbon nanofiber composite material: place the nanofiber obtained in step (2) in a porcelain boat, and heat it from room temperature to 550° C. at a rate of 5° C./min under the condition of passing Ar. Calcined for 3h, the sample Cu-Ag/CNF was prepared.

Calculate the theoretical loading (theoretical mass percentage of substances contained in the product): the loading of Cu is 23.14%, and the loading of Ag is 47.16%.

The specific surface area and electrical conductivity of the composite material prepared in this example were tested, and the measured specific surface area was 653 m ² /g, and the electrical conductivity was 25.1 S/cm.

Example 4

The preparation method of Cu-Ag/carbon nanofiber composite material comprises the following steps:

(1) Preparation of spinning solution: Weigh 2.001g of polyacrylonitrile and dissolve it in 12mL N,N-dimethylformamide solvent, stir evenly to obtain solution A; weigh 1.333g of copper nitrate and pour it into solution A , stirred at room temperature for 3 hours to obtain a mixed solution B; weighed 1.334 g of silver nitrate and poured it into the mixed solution B, and stirred at room temperature for 3.5 hours to obtain a mixed solution C;

(2) Preparation of the precursor: Place the mixed solution C in the syringe, and perform electrospinning at a voltage of 15kV, a flow rate of 1.5mL/h and a height of 15cm. After the electrospinning is completed, dry at room temperature overnight , making Cu-Mn/PAN nanofibers;

(3) Preparation of Cu-Ag/carbon nanofiber composite material: place the nanofibers obtained in step (2) in a porcelain boat, and heat it from room temperature to 500°C at a rate of 5°C/min under the condition of passing _N2 , Calcined for 5h, the prepared sample Cu-Ag/CNF.

Calculate the theoretical loading (theoretical mass percentage of substances contained in the product): the loading of Cu is 17.00%, and the loading of Ag is 31.89%.

The specific surface area and electrical conductivity of the composite material prepared in this example were tested, and the measured specific surface area was 645 m ² /g, and the electrical conductivity was 20.8 S/cm.

Example 5

The preparation method of Cu-Ag/carbon nanofiber composite material comprises the following steps:

(1) Preparation of spinning solution: Weigh 2.504g of polyacrylonitrile and dissolve it in 12mL of N,N-dimethylformamide solvent, stir well to obtain solution A; weigh 1.331g of copper chloride and pour into solution A , stirred at room temperature for 3 hours to obtain a mixed solution B; weighed 1.330 g of silver chloride and poured it into the mixed solution B, and stirred at room temperature for 3.5 hours to obtain a mixed solution C;

(2) Preparation of the precursor: place the mixed solution C in the syringe, and perform electrospinning at a voltage of 10kV, a flow rate of 2mL/h and a height of 15cm. After the electrospinning is completed, dry at room temperature overnight. Prepare Cu-Ag/PAN nanofibers;

(3) Preparation of Cu-Ag/carbon nanofiber composite material: place the nanofibers obtained in step (2) in a porcelain boat, and heat it from room temperature to 700°C at a rate of 5°C/min under the condition of passing _N2 , Calcined for 5h, the prepared sample Cu-Ag/CNF.

Calculate the theoretical loading (theoretical mass percentage of substances contained in the product): the loading of Cu is 18.90%, and the loading of Ag is 30.04%.

The specific surface area and electrical conductivity of the composite material prepared in this example were tested, and the measured specific surface area was 644 m ² /g, and the electrical conductivity was 20.9 S/cm.

Comparative Example 1

The preparation method of Cu/carbon nanofiber composite material comprises the following steps:

(1) Preparation of spinning solution: Weigh 1.203g of polyacrylonitrile and dissolve it in 12mL of N,N-dimethylformamide solvent, stir well to obtain solution A; weigh 1.021g of copper chloride and pour into solution A , stirred at room temperature for 5 hours to obtain a mixed solution B1;

(2) Preparation of the precursor: place the mixed solution B1 in the syringe, and perform electrospinning at a voltage of 20kV, a flow rate of 1mL/h and a height of 16cm. After the electrospinning is completed, dry at room temperature overnight. Prepare Cu/PAN nanofibers;

(3) Preparation of Cu/carbon nanofiber composite material: place the nanofibers obtained in step (2) in a porcelain boat, heat from room temperature to 800°C at a rate of 5°C/min under the condition of passing _N2 , and calcinate 11h, the product Cu/CNF was obtained.

Specific surface area and electrical conductivity were tested for this comparative example, and the test results are shown in Table 1.

Comparative Example 2

The preparation method of Ag/carbon nanofiber composite material comprises the following steps:

(1) Preparation of spinning solution: Weigh 1.105g of polyacrylonitrile and dissolve it in 12mL N,N-dimethylformamide solvent, stir well to obtain solution A; weigh 1.331g of silver nitrate and pour it into solution A , stirred at room temperature for 3 hours to obtain a mixed solution C1;

(2) Preparation of the precursor: place the mixed solution C1 in the syringe, and perform electrospinning at a voltage of 15kV, a flow rate of 1mL/h and a height of 15cm. After the electrospinning is completed, dry at room temperature overnight. Prepare Ag/PAN nanofibers;

(3) Preparation of Ag/carbon nanofiber composite material: place the precursor obtained in step (2) in a porcelain boat, heat it from room temperature to 450°C at a rate of 5°C/min under the condition of passing _N2 , and calcinate After 2.3h, the sample Ag/CNF was prepared.

Specific surface area and electrical conductivity were tested for this comparative example, and the test results are shown in Table 1.

Comparative Example 3

The preparation method of Cu-CuO/carbon nanofiber composite material comprises the following steps:

(1) Preparation of spinning solution: Weigh 1.104g of polyacrylonitrile and dissolve it in 12mL of N,N-dimethylformamide solvent, stir evenly to obtain solution A; weigh 1.331g of copper acetate and pour it into solution A , stirred at room temperature for 3 hours to obtain a mixed solution B;

(2) Preparation of the precursor: place the mixed solution B in the syringe, and perform electrospinning at a voltage of 15kV, a flow rate of 1mL/h and a height of 15cm. After the electrospinning is completed, dry at room temperature overnight. Prepare Cu-CuO/PAN nanofibers;

(3) Preparation of Cu-CuO/carbon nanofiber composite material: the precursor obtained in step (2) was placed in a porcelain boat, and heated from room temperature to 700 °C at a rate of 5 °C/min under the condition of passing _N2 , Calcined for 10.2h, the prepared sample Cu-CuO/CNF.

Specific surface area and electrical conductivity were tested for this comparative example, and the test results are shown in Table 1.

The results of specific surface area and electrical conductivity of the products of Example 1 and Comparative Examples 1-3 are shown in Table 1.

Table 1 embodiment 1 and the specific surface area and conductivity of comparative examples 1～3 products

As can be seen from Table 1, the specific surface area ratio and electrical conductivity of Cu-Ag/CNF in Example 1 are larger than those of Comparative Examples 1-3, and the higher specific surface area can produce more active sites to make electrons or ions It is easier to transfer; and the higher conductivity can improve the cycle performance of Cu-Ag/CNF as an electrode material, thereby increasing the service life. These two points are further reflected in the application examples.

Application example 1

The composite material prepared in Example 1 was applied to the anode material of a supercapacitor and electrochemically tested; the products prepared in Comparative Examples 1-3 were applied to the anode material of a supercapacitor and electrochemically tested.

All electrochemical performance tests were completed on Shanghai Chenhua CHI660 electrochemical workstation. Three-electrode system is adopted: glassy carbon electrode (GC) is used as the working electrode A platinum wire electrode was used as the counter electrode, and a saturated calomel electrode (SCE) was used as the reference electrode. In the experiments, all potentials are relative to SCE, and all experiments are performed at room temperature. Before using the GC electrode, use Al ₂ O ₃ powder Repeatedly polish and polish the suede, then ultrasonically clean it with absolute ethanol and distilled water, and dry it for later use.

Electrode preparation: Mix 5 mg of sample, 1.25 mL of water and 0.25 mL of Nafion solvent, and ultrasonically dissolve the sample for 5 minutes. Finally, use a pipette gun to take 6.4 microliters of the solution and drop it on the working electrode. After drying for 2 hours at a constant temperature of 80°C in a vacuum drying oven, perform cyclic voltammetry and electrochemical performance of constant current charge and discharge in an electrolyte of 2M KOH. test.

Measure the specific capacitance of embodiment 1 and comparative examples 1～3 as shown in Figure 5, specific capacitance is to utilize formula C=I/v, Cs=C/m=I/m/v calculates, and wherein Cs is specific capacitance ( F/g), I is the current (A), m is the mass of the electrode material (g), v is the scanning speed (v/s), and the specific capacitance means the amount of electricity that can be discharged by a battery or active material per unit weight. As shown in Figure 5, the specific capacitance of the Cu/CNF electrode is 78F/g at 5mV/s; the specific capacitance of the Ag/CNF electrode is 110F/g at 5mV/s; the specific capacitance of the Cu-CuO/CNF electrode is 5mV /s is 88F/g; while the specific capacitance of Cu-Ag/CNF electrode material is greater than the other three materials, the specific capacitance value decreases with the increase of scan rate, and its specific capacitance is 151F/g at 5mV/s. .

It is measured that the specific capacitance of the composite material electrodes in Examples 2-5 is about 147-153 F/g.

Cycle durability is one of the most important electrochemical properties of supercapacitors. The measured cycle performance of Example 1 and Comparative Examples 1 to 3 is shown in Figure 6, which shows the change of the capacitance of the electrode at a current density of 10A/g in a constant current charge-discharge test for 2000 cycles. It can be seen from Figure 6 that the cycle performance of Cu-Ag/CNF is obviously better than that of the other three materials, and the long-term operation under the condition of high current density, the capacitance retention ability is still very good. After 2000 cycles, the measured Cu-Ag/CNF The capacitance retention rate of the Ag/CNF electrode is 95.4%. This is because the dense Ag and Cu metal particles can provide sufficient redox reactions, so that the electrode structure made of Cu-Ag/CNF composite material is not easily deformed and the service life is improved. .

It is measured that the cycle performance of the composite electrodes of Examples 2-5 is between 94% and 97% after 2000 cycles under the condition of high current density.

The Cu-Ag/CNF composite material prepared by the method of the present invention has higher specific surface area and electrical conductivity, and the higher specific surface area can generate more active sites so that electrons or ions can be transferred more easily, and can be used in super The anode material of the capacitor can effectively produce electrode materials with large specific capacitance, good cycle performance, long life, and low pollution. This is because the metal Cu and Ag loaded on the carbon fiber help to improve the conductivity of the electrode to a certain extent Coulombic efficiency, and ultimately improve the cycle performance of the electrode.

Claims (10)

1. a kind of Cu-Ag/ carbon nano-fiber composite material, which is characterized in that the structure of the composite material is in carbon Nanowire The load capacity wt% of carried metal elemental copper and silver in dimension, the metal simple-substance copper and silver is respectively 17%~29% and 30%~ 58%.

2. a kind of preparation method of Cu-Ag/ carbon nano-fiber composite material according to claim 1, which is characterized in that packet Include following steps:

(1) preparation of spinning solution: polyacrylonitrile is dissolved in good solvent, solution A is uniformly mixing to obtain；Mantoquita is poured into solution A In, mixed solution B is stirred to get at room temperature；Silver salt is poured into mixed solution B, stirs to get mixed solution C at room temperature；

(2) preparation of presoma: mixed solution C is subjected to electrostatic spinning, is dried at room temperature for after the completion of electrostatic spinning, before being made Drive body Cu-Ag/PAN nanofiber；

(3) preparation of Cu-Ag/ carbon nano-fiber composite material: presoma obtained by step (2) is placed in calcine under inert gas and is made Obtain Cu-Ag/ carbon nano-fiber composite material.

3. a kind of preparation method of Cu-Ag/ carbon nano-fiber composite material according to claim 2, which is characterized in that step Suddenly good solvent described in (1) is N,N-dimethylformamide.

4. a kind of preparation method of Cu-Ag/ carbon nano-fiber composite material according to claim 2, which is characterized in that step Suddenly mantoquita described in (1) is copper acetate, copper chloride or copper nitrate；The silver salt is silver acetate, silver chlorate or silver nitrate.

5. a kind of preparation method of Cu-Ag/ carbon nano-fiber composite material according to claim 2, which is characterized in that step Suddenly mantoquita in (1), silver salt, polyacrylonitrile mass ratio be 1:1:(0.1~5).

6. a kind of preparation method of Cu-Ag/ carbon nano-fiber composite material according to claim 5, which is characterized in that step Suddenly mantoquita in (1), silver salt, polyacrylonitrile mass ratio be 1:1:(0.5~5).

7. a kind of preparation method of Cu-Ag/ carbon nano-fiber composite material according to claim 2, which is characterized in that step Suddenly electrostatic spinning described in (2) is carried out at 10~20kV of voltage, 0.8~2mL/h of flow velocity, 10~20cm of height.

8. a kind of preparation method of Cu-Ag/ carbon nano-fiber composite material according to claim 2, which is characterized in that step Suddenly calcining described in (3) is carried out at 450~700 DEG C of temperature, 2~5h of time.

9. a kind of preparation method of Cu-Ag/ carbon nano-fiber composite material according to claim 2, which is characterized in that step Suddenly inert gas described in (3) is N₂Or Ar.

10. one kind is by Cu-Ag/ carbon nano-fiber composite material described in claim 1 in supercapacitor positive electrode material Application.