CN107195894A - A kind of metal carbon nano-fiber composite material and its preparation method and application - Google Patents

Abstract

The invention relates to a metal-carbon nanofiber composite material and its preparation method and application, which solves the technical problem that the spinning amount of metal active materials in existing materials is relatively low. The metal-carbon nanofiber composite material in the invention includes carbon nanofiber Fiber and bulk metal active materials; the surface of the bulk metal active material is coated with polymer-based carbon, and the interior is a nano-spherical material; the bulk metal active material is drawn by carbon nanofibers and entangled by carbon nanofibers; metal The mass fraction of the active material in the metal carbon nanofiber composite material is 30-70%. The invention also provides its preparation method and application. The invention can be used in the field of battery material preparation.

Description

A kind of metal carbon nanofiber composite material and its preparation method and application

technical field

The invention relates to the field of battery materials, in particular to a metal carbon nanofiber composite material and its preparation method and application.

Background technique

In recent years, the shortage of oil resources and the aggravation of environmental problems have forced people to develop some cleaner and more efficient energy storage devices. Among all energy storage devices, lithium-ion batteries are widely used due to their high energy density and long cycle life. However, due to the limited reserves of lithium metal in the world, researchers have begun to develop energy storage devices such as sodium-ion batteries, magnesium-ion batteries, and aluminum-ion batteries. At the same time, people's demand for energy storage devices is gradually diversifying, and the research and development of flexible electrode materials has become an important scientific research topic.

Electrospinning has the advantages of simple preparation equipment, low cost, more spinnable materials, strong process controllability, and easy industrialization. Among all the researches involving flexible electrode materials, electrospinning has attracted much attention as a means to prepare flexible electrode materials.

At present, the research on the electrospinning method mainly focuses on dispersing the metal active material inside the fiber to obtain the carbon nanofiber composite material. The above method can solve the problem of large volume expansion of most electrode materials, and at the same time can increase the conductivity of the material, which is beneficial to improving the electrochemical performance of the electrode material.

However, the spinning amount of metal active materials in this method is relatively low, and the electrospinning method has high requirements for the selection of the solution system, the setting of the electrospinning parameters, and the selection of heat treatment. The structure also has a large influence, and a lot of research is still needed to overcome the existing problems. At present, the research on classical spinning at home and abroad mainly focuses on dispersing nanomaterials in the interior of fibers to obtain carbon nanofiber composite materials. There are few reports on the combination of micron-scale materials and electrospinning.

Contents of the invention

The present invention aims to solve the technical problem of low spinning amount of metal active materials in existing materials, and provides a metal-carbon nanofiber composite material obtained by electrospinning micron-scale materials and its preparation method and application.

To this end, the present invention provides a metal-carbon nanofiber composite material, the metal-carbon nanofiber composite material includes carbon nanofibers and metal active materials, the surface of the bulk metal active material is coated with polymer-based carbon, and the inner It is a nano-spherical material; at the same time, the bulk metal active material is drawn by carbon nanofibers and entwined by carbon nanofibers; the mass fraction of the metal active material in the metal-carbon nanofiber composite material is 30-70%.

Preferably, the metal active material is iron citrate, bismuth citrate, cobalt citrate, iron ammonium citrate, nickel citrate, zinc citrate, titanium citrate, zirconium citrate, tin citrate, magnesium citrate or citric acid A material formed after one or more carbonizations of copper.

Preferably, the polymer is one or a combination of polyvinylpyrrolidone, polyacrylonitrile, polypyrrole, polyimide or polyvinyl alcohol.

The present invention also provides a method for preparing a metal-carbon nanofiber composite material, which includes the following steps: (1) configuring an electrospinning solution: adding 1 to 10 wt% of a polymer into an organic solution, and placing it at 60 to 90°C Constant temperature treatment in an oven for 3 to 30 hours, then adding the metal precursor, and then stirring for 4 to 24 hours to obtain an electrospinning solution, the weight ratio of the metal precursor to the polymer is (0.5 to 10): 1; (2) Preparation of composite nanofiber membrane by electrospinning method: the parameters of the electrospinning method used: the inner diameter of the syringe needle is 0.9-1.6mm, the temperature is 15-40°C, the relative humidity is <30%, and the electrostatic voltage is 15-22kV , the flow rate of spinning solution is 0.4～1.5ml/h, the receiving distance is 15～30cm, the rotary drum speed is 500～1200rpm, and single needle or multi-needle spinning is adopted; (3) heat treatment: the step (2) obtained The composite nanofiber membrane is heat-treated in a nitrogen atmosphere at 600-1000°C, the heating rate is 1-10°C/min, the cooling rate is 1-10°C/min, and the holding time is 1-5 hours to obtain the final product.

Preferably, the polymer in step (1) is one or a combination of polyvinylpyrrolidone, polyacrylonitrile, polypyrrole, polyimide or polyvinyl alcohol.

Preferably, the solvent of step (1) is absolute ethanol, propylene carbonate, ethyl acetate, butylene carbonate, N,N-dimethylacetamide, N,N-dimethylformamide, or N- One or more combinations of methylpyrrolidone.

Preferably, the metal precursor of step (1) is iron citrate, bismuth citrate, cobalt citrate, ferric ammonium citrate, nickel citrate, zinc citrate, titanium citrate, zirconium citrate, tin citrate, lemon citrate One or more combinations of magnesium citrate or copper citrate.

Preferably, the metal precursor in step (1) is micron-sized particles, which are micron-sized in one dimension, two dimensions or three dimensions.

The invention also provides the application of the metal-carbon nanofiber composite material as a positive electrode or negative electrode material of a battery.

Preferably, it is applied to one or more of lithium-ion batteries, sodium-ion batteries, zinc-ion batteries or magnesium-ion batteries.

The present invention has the following advantages:

(1) In the present invention, micron-scale materials are electrospun to obtain a battery material with a new structure. The method greatly improves the spinning-in amount of the active substance, which can reach more than 65%. The structural characteristics of composite materials are mainly that micron-scale materials appear outside carbon nanofibers, the surface is covered by a layer of polymer-based carbon, and the internal materials become nanomaterials after carbonization. At the same time, both ends of the block are drawn by two carbon nanofibers and wound by the rest of the carbon nanofibers, achieving double protection. This structure can provide more ion and electron transport channels for the material, and at the same time facilitates the infiltration of the electrolyte, so that the electrode material has better electrochemical performance.

(2) The present invention uses electrospinning as a method to prepare composite nanofiber membranes, which can be used as flexible electrode materials without conductive agents and binders. The invention has the advantages of simple process, strong controllability, low cost, low carbon and environmental protection, and is convenient for industrial popularization and application.

Description of drawings

Fig. 1 is the optical photo of the flexible electrode material that the embodiment of the present invention 1 prepares;

Fig. 2 is the scanning electron microscope figure of embodiment 1 of the present invention;

Fig. 3 is the transmission electron microscope figure of embodiment 1 of the present invention;

Fig. 4 is a diagram of the cycle discharge capacity of the product of Example 1 of the present invention as the negative electrode of a lithium ion battery.

detailed description

The following examples further illustrate the present invention, and the following descriptions are only for explaining the present invention, and do not limit its content.

Example 1

Configure the electrospinning solution: add 1g of polyacrylonitrile to 10g of N,N-dimethylformamide solution, put it in an oven at 60°C for 30 hours, then add 1.9g of micron-sized bismuth citrate, and then Stir for 24 hours to prepare an electrospinning solution, the mass ratio of the metal precursor to the polymer is 1.9:1;

Preparation of composite nanofiber membrane by electrospinning process: Pour the electrospinning solution into a syringe with a needle with an inner diameter of 1.2mm, and electrospin at an injection speed of 1ml/h at a voltage of 20kV in an environment with a relative humidity of <30% at room temperature silk for 8 hours, the receiving distance is 20cm, and the rotary drum speed is 1000rpm, and the composite nanofiber membrane is obtained;

Heat treatment process: heat-treat the obtained composite nanofiber membrane in a nitrogen atmosphere at 600°C with a heating rate of 3°C/min and a holding time of 2 hours to obtain the final composite carbon nanofiber membrane;

Electrochemical test: cut the product into discs with a diameter of 12 mm, assemble a lithium-ion battery, and perform electrochemical tests.

Example 2

Configure the electrospinning solution: add 0.5g of polyacrylonitrile to 5g of propylene carbonate solution, put it in an oven at 60°C for 20 hours at a constant temperature, then add 5g of micron-scale ferric citrate, and then stir for 24 hours to obtain Electrospinning solution, the ratio of metal precursor to polymer is 10:1;

Preparation of composite nanofibrous membrane by electrospinning process: Pour the electrospinning solution into a syringe with a needle with an inner diameter of 0.9mm, and in an environment with a relative humidity of <30% at room temperature, electrospin the electrospinning solution at an injection speed of 0.8ml/h at a voltage of 22kV Spinning for 6 hours, the receiving distance is 30cm, and the rotating speed of the drum is 1200rpm, and the composite nanofiber film is obtained;

Heat treatment process: heat-treat the obtained composite nanofiber membrane in a nitrogen atmosphere at 1000°C with a heating rate of 5°C/min and a holding time of 5 hours to obtain the final composite carbon nanofiber membrane;

Electrochemical test: cut the product into discs with a diameter of 12 mm, assemble a lithium-ion battery, and perform electrochemical tests.

Example 3

Prepare the electrospinning solution: add 5g of polyvinylpyrrolidone to 10g of N,N-dimethylacetamide solution, put it in an oven at 90°C for 12 hours, then add 2.5g of micron-sized molybdenum citrate, and then Stir for 4 hours to prepare an electrospinning solution, the ratio of the metal precursor to the polymer is 0.5:1;

Preparation of composite nanofiber membrane by electrospinning process: pour the electrospinning solution into a double-headed syringe with a needle with an inner diameter of 1.6mm, and inject at a voltage of 0.4ml/h at 22kV in an environment with a relative humidity of <30% at room temperature The speed electrospinning was 10 hours, the receiving distance was 15cm, and the rotating speed of the drum was 500rpm to prepare a composite nanofiber membrane;

Heat treatment process: heat-treat the obtained composite nanofiber membrane in a nitrogen atmosphere at 800°C with a heating rate of 10°C/min and a holding time of 1 hour to obtain the final composite carbon nanofiber membrane;

Electrochemical test: cut the product into discs with a diameter of 12mm, assemble a sodium ion battery, and perform electrochemical tests.

Example 4

Configure the electrospinning solution: add 2.74g of polyvinylpyrrolidone to 8g of N,N-dimethylformamide solution, put it in an oven at 80°C for 3 hours, then add 1.37g of micron-sized bismuth citrate, Then stir for 12 hours to prepare an electrospinning solution, the ratio of the metal precursor to the polymer is 0.5:1;

Preparation of composite nanofibrous membrane by electrospinning process: Pour the electrospinning solution into a syringe with a needle with an inner diameter of 1.0mm, and in an environment with a relative humidity of <30% at room temperature, electrospin the electrospinning solution at an injection speed of 0.9ml/h at a voltage of 22kV Spinning for 10 hours, the receiving distance is 15cm, and the drum rotating speed is 500rpm to prepare a composite nanofiber membrane;

Heat treatment process: heat-treat the obtained composite nanofiber membrane in a nitrogen atmosphere at 600°C with a heating rate of 1°C/min and a holding time of 4 hours to obtain the final composite carbon nanofiber membrane;

Electrochemical test: cut the product into discs with a diameter of 12 mm, assemble a magnesium ion battery, and perform electrochemical tests.

Example 5

Prepare electrospinning solution: add 1% polyvinylpyrrolidone to 10g N,N-dimethylformamide solution, put it in an oven at 80°C for 3 hours, then add 3.6g nickel citrate, and then stir for 12 hours , to prepare an electrospinning solution, the ratio of the metal precursor to the polymer is 3.6:1;

Preparation of composite nanofibrous membrane by electrospinning process: Pour the electrospinning solution into a syringe with a needle with an inner diameter of 1.2mm, and in an environment with a relative humidity of <30% at room temperature, electrospin the electrospinning solution at an injection speed of 0.8ml/h at a voltage of 20kV Spinning for 8 hours, the receiving distance is 15cm, and the rotary drum speed is 500rpm, and the composite nanofiber film is obtained;

Heat treatment process: heat-treat the obtained composite nanofiber membrane in a nitrogen atmosphere at 700°C with a heating rate of 5°C/min and a holding time of 3 hours to obtain the final composite carbon nanofiber membrane;

Electrochemical test: cut the product into discs with a diameter of 12 mm, assemble a lithium-ion battery, and perform electrochemical tests.

Claims (10)

1. A metal-carbon nanofiber composite material is characterized in that it includes carbon nanofibers and bulk metal active materials; the surface of the bulk metal active materials is coated with polymer-based carbon, and the inside is a nano-spherical material ; the bulk metal active material is pulled by the carbon nanofiber and entwined by the carbon nanofiber; the mass fraction of the metal active material in the metal carbon nanofiber composite material is 30-70%. 2. The metal-carbon nanofiber composite material according to claim 1, wherein the bulk metal active material is iron citrate, bismuth citrate, cobalt citrate, ferric ammonium citrate, nickel citrate, citric acid A material formed after carbonization of one or more of zinc, titanium citrate, zirconium citrate, tin citrate, magnesium citrate or copper citrate. 3. The metal-carbon nanofiber composite material according to claim 1, wherein the polymer is one or both of polyvinylpyrrolidone, polyacrylonitrile, polypyrrole, polyimide or polyvinyl alcohol combination. 4. A preparation method of metal carbon nanofiber composite material, characterized in that it comprises the steps: (1) Prepare the electrospinning solution: add 1-10wt% polymer into the organic solution, put it in an oven at 60-90°C for 3-30 hours, then add the metal precursor, and then stir for 4-24 hours , to prepare an electrospinning solution, the mass ratio of the metal precursor to the polymer is (0.5-10):1; (2) Preparation of composite nanofiber membrane by electrospinning method: the parameters of the electrospinning method used: the inner diameter of the syringe needle is 0.9-1.6mm, the temperature is 15-40°C, the relative humidity is <30%, and the electrostatic voltage is 15-22kV , the spinning liquid flow rate is 0.4-1.5ml/h, the receiving distance is 15-30cm, the rotating drum speed is 500-1200rpm, and single-needle or multi-needle spinning is used; (3) Heat treatment: heat-treat the composite nanofiber membrane obtained in the step (2) in a nitrogen atmosphere at 600-1000° C., the heating rate is 1-10° C./min, and the cooling rate is 1-10° C./min. The holding time is 1 to 5 hours to obtain the final product. 5. the preparation method of metal-carbon nanofiber composite material according to claim 4, is characterized in that, the polymer of described step (1) is polyvinylpyrrolidone, polyacrylonitrile, polypyrrole, polyimide or polyvinylpyrrolidone. One or a combination of two vinyl alcohols. 6. the preparation method of metal-carbon nanofiber composite material according to claim 4, is characterized in that, the solvent of described step (1) is dehydrated alcohol, propylene carbonate, ethyl acetate, butylene carbonate, N , one or more combinations of N-dimethylacetamide, N,N-dimethylformamide, or N-methylpyrrolidone. 7. the preparation method of metal-carbon nanofiber composite material according to claim 4, is characterized in that, the metal precursor of described step (1) is iron citrate, bismuth citrate, cobalt citrate, ferric ammonium citrate , one or more combinations of nickel citrate, zinc citrate, titanium citrate, zirconium citrate, tin citrate, magnesium citrate or copper citrate. 8. The preparation method of metal-carbon nanofiber composite material according to claim 4, characterized in that, the metal precursor of the step (1) is a micron-scale particle, which is in one dimension, two dimensions or three Dimensionally micron-sized. 9. The application of the metal-carbon nanofiber composite material as claimed in claim 1 as a battery positive or negative electrode material. 10. The application of the metal-carbon nanofiber composite material according to claim 9 as the battery positive pole or negative pole, is characterized in that, it is applied to one or more of lithium-ion batteries, sodium-ion batteries, zinc-ion batteries or magnesium-ion batteries Several kinds.