CN109930241A - A kind of electrode material and its preparation and application with core-shell structure - Google Patents

Abstract

A kind of electrode material with core-shell structure, it is the nanofibrous structures that diameter is micron or submicrometer structure, diameter dimension range is 50-5000nm, it is referred to as stratum nucleare by core of fiber filament, in fiber filament outer surface package film be shell, shell thickness and stratum nucleare radii ratio are 10:1 between 1:10, and it is nanoscale porous structure that shell structurre, which further includes aperture, range of aperture size be 2 to 50nm porosity be 10 to 70%.Compared with prior art, electrode material prepared by the present invention it is structurally ordered it is controllable, mass-transfer performance is good, noble metal utilisation is high, ion transmission efficiency is high, practical.

Description

A kind of electrode material with core-shell structure and its preparation and application

technical field

The invention relates to a novel core-shell structure electrode and a preparation method thereof. Specifically, the core-shell structure electrode has adjustable inner and outer fiber diameters, and the core-shell ratio and outer shell porosity can be adjusted, and can be used for proton exchange membranes. In fuel cells, direct liquid fuel cells, metal-air batteries and supercapacitors, lithium-ion batteries and other electrodes.

The present invention also relates to the preparation method of the above-mentioned composite material.

Background technique

Electrode materials with ordered structures have great potential for applications in the fields of electronics, energy, and biomedicine. Conductive materials suitable for electrochemical environments in electrodes are usually various carbon-based nanomaterials, such as carbon nanotubes, graphene, activated carbon, and the like. A notable feature of this type of material is that it usually exhibits flexibility, and in the process of forming a porous electrode, its pore structure is mostly a secondary pore structure formed by particle accumulation. In the application field of fuel cell electrodes, the controllability of the pore structure on the structure and the controllability of charge and material conduction are the basic requirements for studying the basic process of the electrode, explaining the electrochemical behavior of the electrode, and improving the performance of the electrode. In the traditional electrode preparation method, the electrode material slurry is cross-linked and stacked on the substrate through various coating techniques. The electrode layer often has uncontrollable porosity, pore size and pore shape, and it is difficult to achieve electrode performance and structure efficiency. In-depth research is also difficult to achieve the improvement of electrode performance.

At present, the research on nanofibers and core-shell structural fibers is still in the stage of material synthesis and exploration. In the practical application of electrodes, there are still shortcomings in performance, cost, and life, and the structural characteristics are difficult to effectively control. The ionic conductivity, electrode catalytic performance It is still difficult to meet the needs of practical applications. In view of this, it is one of the keys to the development of porous electrodes to develop an electrode preparation method with controllable pore size and porosity, simple and easy preparation process, and suitable for most electrode materials.

SUMMARY OF THE INVENTION

The present invention will prepare an electrode material with a core-shell structure. The core-shell structure electrode has a nanofiber structure on the microscopic topography, and the shell structure also has a porous topography. The electrode material of this structure is made of electrospinning. It can be used as a porous electrode for fuel cells, metal-air batteries, electrochemical sensors and other devices.

For achieving the above object, the present invention adopts the following concrete scheme to realize:

An electrode material with a core-shell structure, which is a nanofiber structure with a diameter of a micrometer or a submicrometer structure, and a diameter range of 50-5000nm. The membrane is a shell layer, and the ratio of the thickness of the shell layer to the radius of the core layer is between 10:1 and 1:10. The shell layer structure also includes a nano-scale porous structure with a pore size ranging from 2 to 50 nm and a porosity of 10 to 70 nm. %.

The core-layer structure constituting material of the core-shell structure electrode material is an ion conductor material, including one or more of perfluorosulfonic acid polymer, polybenzimidazole, and polyether ether ketone.

The shell structure constituting material of the core-shell structure electrode material is an electronic conductor material, and the electronic conductor material includes one or two or more of platinum, gold, silver, ruthenium, palladium or an alloy of any two or more of them. , wherein electrocatalytic materials are not added or can be added, and electrocatalytic materials include one or more of nitrogen-doped amorphous carbon materials, transition metal nitrides, and transition metal oxides.

The generation template of the porous structure in the shell structure of the core-shell structure electrode material includes one or more of polyacrylic acid, polyethylene oxide, and polyvinyl pyrrolidone.

The preparation method of the core-shell structure electrode material includes the following preparation steps, as shown in FIG. 1 .

c. Shell material spinning solution preparation

One or more of chloroplatinic acid, chloroauric acid, silver nitrate, ruthenium chloride, chloropalladic acid of a certain quality, or chloroplatinic acid, chloroauric acid, silver nitrate, ruthenium chloride, chloropalladic acid One or two or more in and one or more of iron nitrate, nickel nitrate, cobalt nitrate, copper nitrate are 5:1 to 1:5 according to the ratio of substance amount, add water, dimethylformaldehyde In one or more than two solvents of amide, methanol or ethanol, the mass concentration of the precious metal is 1% to 10%, and after fully dissolving, the shell material solution is obtained.

d. One or more of polyacrylic acid, polyethylene oxide, and polyvinyl pyrrolidone of a certain quality are added to the above-mentioned solution, and the mass concentration thereof is 1% to 20%. , stirring for 2 to 48h, fully dissolving and homogeneously waiting for use to obtain a spinning solution.

e. Preparation of core layer material solution

Dissolve a certain quality of perfluorosulfonic acid polyion, polybenzimidazole, and polyether ether ketone in one or more of one or more of water, dimethylformamide, methanol or ethanol. In the solvent, the mass concentration is 1% to 20%, and then one or more of polyacrylic acid, polyethylene oxide, and polyvinyl pyrrolidone are added, and the mass concentration is 0% to 10%. Under the conditions of room temperature to 80 ° C , stir for 2 to 48h, fully dissolve and evenly wait for use.

c. Electrospinning Preparation of Core-Shell Structure Electrode Materials

The spinning solution prepared in the above step a is placed at the outer layer inlet of the coaxial spinning injection device, and the spinning solution prepared in the above step b is placed in the inner layer inlet of the coaxial spinning injection device, and the outer layer feeding speed is 0.1 to 2 mL/min, inner layer feed rate to outer layer feed rate ratio of 1:10 to 10:1, needle distance from receiver 5 to 20 cm, and spinning potential of 10 to 30 kV. The prepared composite material is ready for use.

The composite material prepared above is reduced by a hydrogen reduction method or a chemical method. The hydrogen reduction method is used to reduce the composite material, and the composite material is placed in a tube furnace, and a hydrogen-argon mixture gas (hydrogen concentration is 5%) with a flow rate of 10 to 100 mL/min is introduced, the reaction temperature is 200 to 400 ° C, and the reaction time is 2 To 8h; using chemical reduction method, the composite material is placed in an aqueous solution of sodium borohydride or hydrazine hydrate with a concentration of 0.1 to 2M, and the reaction is carried out at room temperature for 10 to 180min. Thereby, the core-shell structure electrode material was prepared.

The core-shell structure electrode material can be used in proton exchange membrane fuel cells, or metal-air batteries, or supercapacitors, or lithium-ion batteries.

Compared with the prior art, the present invention has the following advantages:

1. The structure is orderly and controllable: the fiber diameter and pore density of the core-shell structure electrode material prepared by the method of the present invention can be controlled by the parameters of the preparation process.

2. Good mass transfer performance: the core-shell structure electrode material prepared by the method of the present invention has better mass transfer performance due to its increased porosity and orderly pores;

3. High utilization rate of precious metals: For the core-shell structure electrode material prepared by the method of the present invention, most of the precious metal surface can be exposed to the mass transfer channel, so that the utilization rate is relatively high;

4. High ion transport efficiency: the core-shell structure electrode material prepared by the method of the present invention has an orderly and controllable ion transport channel, and its one-dimensional structure can greatly enhance the ion transport process;

5. Strong practicability: Compared with other preparation methods, the electrospinning preparation process of this method has strong controllability, reduces the uncontrollable factors brought by other methods, and has strong practicability.

Description of drawings

FIG. 1 is a schematic diagram of the preparation process and structure of the core-shell structure electrode material of the present invention.

Fig. 2 is a scanning electron microscope photograph of a core-shell structure electrode material prepared by the method of the present invention (Example 1). It can be seen that the core-shell structure electrode material presents a very regular and ordered fiber structure, and the fiber diameter is about 400 nm.

Fig. 3 is a transmission electron microscope photograph of a core-shell structure electrode material prepared by the method of the present invention (Example 1). It can be seen that the core-shell structure electrode material presents a distinct core layer and shell layer structure, the diameter of the core layer is about 200 nm, and the thickness of the shell layer is about 100 nm.

Fig. 4 is a result curve of electrochemical test results of oxygen reduction reaction of a core-shell structure electrode material prepared by the method of the present invention (Example 1, Comparative Example 1 and commercial carbon-supported platinum catalyst). It can be seen from the figure that the oxygen reduction catalytic performance of the core-shell structure electrode material prepared by the method of the present invention is obviously improved.

Detailed ways

The present invention will be described in detail below through examples, but the present invention is not limited to the following examples.

Example 1:

a. Shell material spinning solution preparation

A certain quality of chloroplatinic acid is added to a dimethylformamide solvent to make the mass concentration of the precious metal 5%, and it is fully dissolved and used for later use. A certain mass of polyacrylic acid was added to the above solution to make its mass concentration 5%, stirred at room temperature for 24 hours, fully dissolved and evenly used for later use.

b. Preparation of core material solution

Dissolve a certain mass of perfluorosulfonic acid polyion in methanol solvent with a mass concentration of 10%, then add polyethylene oxide with a mass concentration of 1%, stir at room temperature for 24 hours, fully dissolve and evenly use it before use .

c. Electrospinning Preparation of Core-Shell Structure Electrode Materials

The spinning solution prepared in the above step a is placed at the outer layer inlet of the coaxial spinning injection device, and the spinning solution prepared in the above step b is placed in the inner layer inlet of the coaxial spinning injection device, and the outer layer feeding speed is 0.6 mL/min, the ratio of the inner layer feeding speed to the outer layer feeding speed is 1:2, the needle distance is 10 cm from the receiver, and the spinning potential is 20 kV. The prepared composite material is ready for use.

The composites prepared above were reduced by the hydrogen reduction method. The composite material was placed in a tube furnace, and a mixture of hydrogen and argon with a flow rate of 40 mL/min (the volume concentration of hydrogen was 5%) was passed through, the reaction temperature was 300 °C, and the reaction time was 4 h. Thereby, the core-shell structure electrode material was prepared. The diameter size of the core-shell structure electrode material ranges from 200 to 300 nm, the ratio of the thickness of the shell layer to the radius of the core layer is 2:1; the pore size of the shell layer ranges from 10 to 20 nm, and the porosity is 50%.

Comparative Example 1:

a. Spinning Solution Preparation

A certain quality of chloroplatinic acid is added to a dimethylformamide solvent to make the mass concentration of the precious metal 5%, and it is fully dissolved and used for later use. A certain mass of polyacrylic acid was added to the above solution to make its mass concentration 5%, stirred at room temperature for 24 hours, fully dissolved and evenly used for later use.

b. Electrospinning Preparation

The spinning solution prepared in the above step a was placed in a spinning injection device, the feed rate was 0.6 mL/min, the needle distance was 10 cm from the receiver, and the spinning potential was 20 kV. The prepared composite material is ready for use.

The composites prepared above were reduced by the hydrogen reduction method. The composite material was placed in a tube furnace, and a hydrogen-argon mixture with a flow rate of 40 mL/min (hydrogen concentration of 5%) was passed through, the reaction temperature was 300 °C, and the reaction time was 4 h. Thus, an electrode material of Comparative Example 1 was prepared.

Comparative Example 2:

a. Shell material spinning solution preparation

A certain quality of chloroplatinic acid is added to a dimethylformamide solvent to make the mass concentration of the precious metal 5%, and it is fully dissolved and used for later use. A certain mass of polyacrylic acid was added to the above solution to make its mass concentration 5%, stirred at room temperature for 24 hours, fully dissolved and evenly used for later use.

Dissolving a certain mass of perfluorosulfonic acid polyion in the above mixed solution, the mass concentration is 1%, stirring at room temperature for 24 hours, fully dissolving and homogeneously before use.

c. Electrospinning Preparation of Core-Shell Structure Electrode Materials

The spinning solution prepared in the above step a was placed in a spinning injection device, the feed rate was 0.6 mL/min, the needle distance was 10 cm from the receiver, and the spinning potential was 20 kV. The prepared composite material is ready for use.

The composites prepared above were reduced by the hydrogen reduction method. The composite material was placed in a tube furnace, and a hydrogen-argon mixture with a flow rate of 40 mL/min (hydrogen concentration of 5%) was passed through, the reaction temperature was 300 °C, and the reaction time was 4 h. Thus, an electrode material of Comparative Example 1 was prepared.

Example 2:

a. Shell material spinning solution preparation

A certain quality of chloroplatinic acid is added to a dimethylformamide solvent to make the mass concentration of the precious metal 5%, and it is fully dissolved and used for later use. A certain mass of polyacrylic acid was added to the above solution to make its mass concentration 5%, stirred at room temperature for 24 hours, fully dissolved and evenly used for later use.

b. Preparation of core material solution

Dissolve a certain mass of perfluorosulfonic acid polyion in methanol solvent with a mass concentration of 10%, then add polyethylene oxide with a mass concentration of 1%, stir at room temperature for 24 hours, fully dissolve and evenly use it before use .

c. Electrospinning Preparation of Core-Shell Structure Electrode Materials

The spinning solution prepared in the above step a is placed at the outer layer inlet of the coaxial spinning injection device, and the spinning solution prepared in the above step b is placed in the inner layer inlet of the coaxial spinning injection device, and the outer layer feeding speed is 0.6 mL/min, the ratio of the inner layer feeding rate to the outer layer feeding rate was 2:1, the needle distance was 10 cm from the receiver, and the spinning potential was 20 kV. The prepared composite material is ready for use.

The composites prepared above were reduced by the hydrogen reduction method. The composite material was placed in a tube furnace, and a hydrogen-argon mixture with a flow rate of 40 mL/min (hydrogen concentration of 5%) was passed through, the reaction temperature was 300 °C, and the reaction time was 4 h. Thereby, the core-shell structure electrode material was prepared. The diameter size of the core-shell structure electrode material ranges from 100 to 200 nm, the ratio of the thickness of the shell layer to the radius of the core layer is 1:1; the pore size of the shell layer ranges from 5 to 10 nm, and the porosity is 40%.

Example 3:

a. Shell material spinning solution preparation

A certain quality of chloroauric acid and ferric nitrate are added in a methanol solvent in a ratio of 1:1 according to the amount of the substance, so that the mass concentration of the precious metal is 10%, and it is fully dissolved and used for later use. A certain mass of polyethylene oxide was added to the above solution to make its mass concentration 5%, stirred for 48 hours under the condition of 80° C., fully dissolved and evenly used before use.

b. Preparation of core material solution

Dissolve a certain mass of polybenzimidazole in an ethanol solvent with a mass concentration of 20%, then add one of the polyvinylpyrrolidones with a mass concentration of 10%, and stir for 18 hours at 40 °C, fully dissolve and uniformly. stand-by.

c. Electrospinning Preparation of Core-Shell Structure Electrode Materials

The spinning solution prepared in the above step a is placed at the outer layer inlet of the coaxial spinning injection device, and the spinning solution prepared in the above step b is placed in the inner layer inlet of the coaxial spinning injection device, and the outer layer feeding speed is 2mL/min, the ratio of the inner layer feeding speed to the outer layer feeding speed is 1:5, the needle distance is 10cm from the receiver, and the spinning potential is 30kV. The prepared composite material is ready for use.

The composites prepared above were chemically reduced. The composite material was placed in an aqueous solution of sodium borohydride with a concentration of 0.1 M, and the reaction was carried out at room temperature for 60 min. Thereby, the core-shell structure electrode material was prepared. The diameter of the core-shell structure electrode material ranges from 300 to 500 nm, the ratio of the thickness of the shell layer to the radius of the core layer is 1:2; the pore size of the shell layer ranges from 30 to 40 nm, and the porosity is 60%.

Compared with the comparative example, the preparation method of the prepared core-shell fiber structure electrode is simple and controllable, the conduction efficiency of the core layer ionic conductor is significantly improved, the utilization efficiency of the shell layer noble metal catalyst is greatly enhanced, and the electrode performance is significantly improved.

Claims (16)

1. an electrode material with a core-shell structure, characterized in that: it is a nanofiber structure with a diameter of a micron or submicron structure; the structure is called a core layer with a fiber filament as the core, and the outer surface of the fiber filament is wrapped. The membrane is a shell layer, the ratio of the thickness of the shell layer to the radius of the core layer is between 10:1 and 1:10, and the shell layer structure also includes a porous structure with a pore size of nanometer. 2 . The electrode material according to claim 1 , wherein the diameter of the nanofiber structure ranges from 50 to 5000 nm. 3 . 3 . The electrode material of claim 1 , wherein the pore size of the shell pores ranges from 2 to 50 nm. 4 . 4. The electrode material of claim 1, wherein the porosity of the shell layer is 10 to 70%. 5 . The electrode material according to claim 1 , wherein the core layer structure constituting material of the core-shell structure electrode material is an ion conductor material; the shell layer structure constituting material is an electron conductor material. 6 . 6. The electrode material according to claim 5, wherein the ion conductor is one of perfluorosulfonic acid polymer, polybenzimidazole, polyether ether ketone and any derivative material of the three One or more than two; the electronic conductor material includes one or more than two alloys of platinum, gold, silver, ruthenium, palladium or any two or more of them; wherein no or non-precious metals can be added Electrocatalytic materials. 7 . The electrode material of claim 6 , wherein the non-noble metal electrocatalytic material is one or more of nitrogen-doped amorphous carbon materials, transition metal nitrides, and transition metal oxides. 8 . 8. a preparation method of the electrode material described in any one of claim 1-7, is characterized in that, comprises the following preparation steps: a. Preparation of shell material spinning solution: adding the precursor of the electron conductor into the solvent to obtain a shell material solution with a mass concentration of the electron conductor precursor of 1% to 10%; adding polyacrylic acid, polyacrylic acid, One or more of polyethylene oxide and polyvinyl pyrrolidone, so that the mass concentration is 1% to 20%, and stirred to obtain a shell spinning solution; b. Preparation of core layer material solution: dissolve the ionic conductor polymer in a solvent to make its mass concentration 1% to 20%, and stir to obtain a core layer spinning solution; c. Electrospinning Preparation of Core-Shell Structure Electrode Materials The spinning solution prepared in the above step a is placed at the outer layer inlet of the coaxial spinning injection device, and the spinning solution prepared in the above step b is placed in the inner layer inlet of the coaxial spinning injection device. The outer layer feeding speed ratio is 1:10 to 10:1, the spinning potential is 10 to 30kV, and the prepared composite material is ready for use; d. The composite material prepared above is reduced by a hydrogen reduction method or a chemical method to obtain a core-shell structure electrode material. 9. the preparation method of electrode material as claimed in claim 8, is characterized in that: The precursor of the electronic conductor described in step a is a precious metal precursor salt, which is one or more of chloroplatinic acid, chloroauric acid, silver nitrate, ruthenium chloride, and chloropalladic acid; The ion conductor polymer described in step b is one or more than two of perfluorosulfonic acid polyion, polybenzimidazole, polyether ether ketone and any derivative material of the three; The solvents described in steps a and b are one or more of water, dimethylformamide, methanol or ethanol; the solvents in steps a and b may be different. 10. The preparation method of electrode material according to claim 8, wherein: The temperature in the preparation process of the spinning solution for the shell layer and the spinning solution for the core layer in steps a and b is room temperature -80° C.; and the stirring time is 2 to 48 hours. 11. The preparation method of electrode material as claimed in claim 8, wherein: The feeding speed of the outer layer in step c is 0.1 to 2 mL/min, and the distance between the needle and the receiver is 5 to 20 cm. 12. The preparation method of electrode material according to claim 8, wherein: In step a, the precursor of the electronic conductor also contains nitrogen-doped amorphous carbon material and/or non-precious metal precursor salt; the non-precious metal precursor salt is one of ferric nitrate, nickel nitrate, cobalt nitrate, and copper nitrate Or two or more kinds; the ratio of the amount of the noble metal precursor salt to the nitrogen-doped amorphous carbon material and/or the non-precious metal precursor salt substance is 5:1 to 1:5. 13. The preparation method of electrode material according to claim 8, wherein: One or more of polyacrylic acid, polyethylene oxide and polyvinyl pyrrolidone may be added to the core layer spinning solution in step b, and the mass concentration should not exceed 10%. 14. The preparation method of electrode material according to claim 8, wherein: The hydrogen reduction method described in step d is to place the composite material in a hydrogen-argon mixed gas for high temperature reaction; The chemical reduction method in step d is to place the composite material in an aqueous solution of sodium borohydride or hydrazine hydrate to react. 15. The preparation method of electrode material according to claim 14, wherein: In the hydrogen reduction method, the volume concentration of hydrogen in the hydrogen-argon mixture is 5 to 20%; the flow rate is 10 to 100 mL/min; the reaction temperature is 200 to 400° C., and the reaction time is 2 to 8 h; The concentration of sodium borohydride or hydrazine hydrate aqueous solution in the chemical reduction method is 0.1 to 2M; the reaction temperature is 10-40° C., and the reaction time is 10 to 180 min. 16. An application of the electrode material according to claims 1-7, characterized in that: the core-shell structure electrode material can be used in proton exchange membrane fuel cells, or metal-air batteries, or supercapacitors, or lithium ion batteries.