Preparation method and application of polyethylene dioxylthiophene-coated iron diselenide

Abstract

The application relates to a preparation method and application of polyethylene dioxothiophene-coated iron diselenide, and relates to a preparation method and application of iron diselenide. The purpose of the application is to solve the problems that the structural instability caused by the inevitable volume change of iron diselenide in the sodium storage reaction process and the poor conductivity in the material interior cause the sodium storage performance to not be fully exerted. The method comprises the following steps: one, preparing a mixed solution; two, carrying out a hydrothermal reaction to obtain iron diselenide; three, ultrasonic dispersion of the iron diselenide and 3,4-ethylenedioxythiophene in deionized water, then adding ammonium persulfate, and carrying out a reaction under stirring at room temperature to obtain polyethylene dioxothiophene-coated iron diselenide. The polyethylene dioxothiophene-coated iron diselenide is used as a negative electrode of a sodium ion battery, and exhibits good rate performance and excellent cycle stability. The application can obtain polyethylene dioxothiophene-coated iron diselenide.

Description

Technical Field

[0001] This invention relates to a method for preparing iron diselenide and its application. Background Technology

[0002] The dwindling lithium resources have caused lithium prices to soar, severely hindering the development of lithium-ion batteries. As an alternative to lithium-ion batteries, sodium-ion batteries, which are lower in cost and safer, are gradually moving towards industrialization. Currently, the main anode material used in sodium-ion batteries is hard carbon, but hard carbon has a low energy density. Together with the similarly low energy density of the cathode material, this results in sodium-ion batteries' energy density not being comparable to that of lithium-ion batteries. It is hoped that this bottleneck can be overcome by using conversion-type materials as the anode.

[0003] Conversion-type anode materials are mainly transition metal chalcogenides, storing charge through multi-electron conversion reactions, thus exhibiting high theoretical specific capacity. Among them, metal selenides have higher intrinsic conductivity than metal oxides and metal sulfides, and due to the ease of metal-selenium bond formation and breakage, they possess faster reaction kinetics. Iron is widely available, abundant, and inexpensive, making iron diselenide a highly competitive material among metal selenides. However, like all conversion-type materials, iron diselenide is inevitably plagued by structural instability caused by its energy storage mechanism. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that the unavoidable volume change of iron diselenide during the sodium storage reaction leads to structural instability and poor internal conductivity of the material, which prevents the full realization of sodium storage performance. The invention provides a method for preparing and applying polyethylene dioxythiophene-coated iron diselenide.

[0005] A method for preparing polyethylene dioxythiophene coated iron diselenide comprises the following steps:

[0006] I. Preparation of mixed solution:

[0007] ① Dissolve selenium powder in hydrazine hydrate to obtain a selenium powder hydrazine hydrate solution;

[0008] ② Dissolve ferrous ammonium sulfate and citric acid in deionized water, then add selenium powder dropwise to a hydrazine hydrate solution, and stir until homogeneous to obtain a mixed solution;

[0009] 2. Pour the mixed solution into a hydrothermal reactor, and then carry out a hydrothermal reaction under high temperature and high pressure to obtain solid reaction product I; wash and dry solid reaction product I to obtain iron diselenide:

[0010] 3. Iron diselenide and 3,4-ethylenedioxythiophene were ultrasonically dispersed in deionized water, and then ammonium persulfate was added. The mixture was reacted under stirring at room temperature to obtain solid reaction product II. Solid reaction product II was washed and dried to obtain iron diselenide coated with polyethylenedioxythiophene.

[0011] A type of polyethylene dioxythiophene-coated iron diselenide is used as the negative electrode in sodium-ion batteries.

[0012] The principle of this invention:

[0013] This invention first synthesizes iron diselenide nanospheres via a hydrothermal method, then combines positively charged ethylenedioxythiophene with negatively charged iron diselenide through electrostatic interaction, followed by in-situ polymerization to form polyethylenedioxythiophene, ultimately yielding polyethylenedioxythiophene-coated iron diselenide. Iron diselenide possesses advantages such as high theoretical specific capacity, weak polyselenide shuttle effect, and abundant reserves. However, iron diselenide undergoes unavoidable volume changes during sodium ion insertion / extraction, leading to reduced structural stability. Furthermore, its poor internal electronic conductivity prevents the full utilization of its sodium storage capacity. The technical solution of this invention utilizes polyethylenedioxythiophene to coat iron diselenide, and the interconnected polyethylenedioxythiophene forms a fast electron transport channel, effectively improving the conductivity of iron diselenide. The polyethylenedioxythiophene coating also alleviates the volume expansion during the sodiumization process of iron diselenide. Therefore, the obtained product exhibits better rate performance and long-term stability.

[0014] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0015] I. This invention uses polyethylene dioxythiophene, which has high conductivity and certain mechanical flexibility, to coat iron diselenide. The permeated polyethylene dioxythiophene layer acts as an interconnected high conductivity network in the entire composite material, effectively improving the conductivity of iron diselenide. Furthermore, the polyethylene dioxythiophene encapsulates the sodium-containing products of iron diselenide, which can buffer a large amount of volume change to stabilize the structure and avoid the aggregation of active materials. Therefore, the prepared material has a long service life.

[0016] 2. In this invention, the polyethylene dioxythiophene coating can alleviate the volume expansion of iron diselenide during the sodiumization process and effectively stabilize the structure of iron diselenide.

[0017] Third, this invention uses iron diselenide coated with polyethylene dioxythiophene as the active material, and prepares the sodium-ion battery anode by mixing and grinding the active material, conductive agent and binder. It has the advantages of good conductivity and high structural stability. When this material is used in sodium-ion batteries, it exhibits good rate performance and excellent cycle stability.

[0018] The present invention can obtain a polyethylene dioxythiophene coated iron diselenide. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating the preparation of polyethylene dioxythiophene-coated iron diselenide in Example 1.

[0020] Figure 2 The figures are microscopic morphology images. In the figure, (a) is a scanning electron microscope image of pure iron diselenide, (b) is a scanning electron microscope image of iron diselenide coated with polyethylene dioxythiophene prepared in Example 1, and (c) is a transmission electron microscope image of iron diselenide coated with polyethylene dioxythiophene prepared in Example 1.

[0021] Figure 3 The figures show XRD and Raman spectra. In the figure, (a) is the XRD spectrum of pure iron diselenide and iron diselenide coated with polyethylene dioxythiophene, and (b) is the Raman spectrum of pure iron diselenide and iron diselenide coated with polyethylene dioxythiophene. In the figure, 1 is pure iron diselenide and 2 is iron diselenide coated with polyethylene dioxythiophene prepared in Example 1.

[0022] Figure 4 The figure shows the rate performance of pure iron diselenide and iron diselenide coated with polyethylene dioxythiophene. In the figure, A is pure iron diselenide and B is iron diselenide coated with polyethylene dioxythiophene prepared in Example 1.

[0023] Figure 5 Cyclic performance of iron diselenide coated with polyethylene dioxythiophene prepared in Example 1. Detailed Implementation

[0024] Specific Implementation Method 1: This implementation method describes a method for preparing polyethylene dioxythiophene coated iron diselenide, which is specifically completed according to the following steps:

[0025] I. Preparation of mixed solution:

[0026] ① Dissolve selenium powder in hydrazine hydrate to obtain a selenium powder hydrazine hydrate solution;

[0027] ② Dissolve ferrous ammonium sulfate and citric acid in deionized water, then add selenium powder dropwise to a hydrazine hydrate solution, and stir until homogeneous to obtain a mixed solution;

[0028] 2. Pour the mixed solution into a hydrothermal reactor, and then carry out a hydrothermal reaction under high temperature and high pressure to obtain solid reaction product I; wash and dry solid reaction product I to obtain iron diselenide:

[0029] 3. Iron diselenide and 3,4-ethylenedioxythiophene were ultrasonically dispersed in deionized water, and then ammonium persulfate was added. The mixture was reacted under stirring at room temperature to obtain solid reaction product II. Solid reaction product II was washed and dried to obtain iron diselenide coated with polyethylenedioxythiophene.

[0030] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the amount of selenium powder mentioned in step one ① is in the volume ratio of 2 mmol:(15 mL to 20 mL) to hydrazine hydrate. The other steps are the same as in Specific Implementation Method One.

[0031] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the molar ratio of ferrous ammonium sulfate to selenium powder in step one, step two, is 1:2. The other steps are the same as in Specific Implementation Method One or Two.

[0032] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the mass ratio of ferrous ammonium sulfate to citric acid in step one, step two, is 1 mmol: 0.1 g. The other steps are the same as in Specific Implementation Methods One to Three.

[0033] Specific Implementation Method Five: The difference between this implementation method and Specific Implementation Methods One to Four is that the amount of ferrous ammonium sulfate mentioned in step one ② and the volume ratio of deionized water are 1 mmol:(25 mL to 35 mL). The other steps are the same as in Specific Implementation Methods One to Four.

[0034] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: the hydrothermal reaction temperature in step two is 120℃~240℃, and the hydrothermal reaction time is 6h~48h; the volume of the hydrothermal reactor liner in step two is 100mL. Other steps are the same as in Specific Implementation Methods One to Five.

[0035] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: the mass ratio of iron diselenide to the volume ratio of 3,4-ethylenedioxythiophene in step three is 100 mg:(50 μL to 150 μL); the reaction time in step three under stirring at room temperature is 8 to 10 hours. Other steps are the same as in Specific Implementation Methods One to Six.

[0036] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: the mass ratio of ferric diselenide to ammonium persulfate in step three is 100:(150-300); the mass ratio of ferric diselenide to deionized water in step three is 100 mg:(70 mL-150 mL). The other steps are the same as in Specific Implementation Methods One to Seven.

[0037] Specific Implementation Method Nine: This implementation method is a method of using ferric diselenide coated with polyethylene dioxythiophene as the negative electrode of a sodium-ion battery.

[0038] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the preparation method of the sodium-ion battery negative electrode is as follows: Polyethylene dioxythiophene coated iron diselenide is used as the active material, and added to N-methylpyrrolidone at a mass ratio of active material:conductive agent:binder of 8:1:1. The mixture is stirred until a uniform slurry is formed, and then coated onto copper foil to obtain the sodium-ion battery negative electrode. The conductive agent is acetylene black, and the binder is polyvinylidene fluoride. Other steps are the same as in Specific Implementation Methods One to Nine.

[0039] The beneficial effects of the present invention are verified using the following embodiments:

[0040] Example 1: A method for preparing polyethylene dioxythiophene coated iron diselenide, specifically completed according to the following steps:

[0041] First, 2 mmol of selenium powder was dissolved in 15 mL of hydrazine hydrate to obtain a hydrazine hydrate solution of selenium powder. 1 mmol of ferrous ammonium sulfate and 0.1 g of citric acid were dissolved in 30 mL of deionized water, and then added dropwise to the hydrazine hydrate solution of selenium powder, stirring thoroughly to obtain a mixed solution. The mixed solution was transferred to a 100 mL polytetrafluoroethylene (PTFE) reactor, which was then placed in an oven at 180°C for 12 hours. After the reaction was complete, the reactor was cooled to room temperature to obtain the reaction product. The reaction product was washed with water five times and with alcohol five times, and finally dried to obtain iron diselenide nanospheres.

[0042] 2. 100 mg of iron diselenide nanospheres and 100 μL of 3,4-ethylenedioxythiophene monomer were ultrasonically dispersed in 80 mL of deionized water. Then, 214 mg of ammonium persulfate was added to the mixture, and the mixture was stirred continuously at room temperature for 10 h. After the reaction was completed, the product was collected, washed with water 5 times, and dried to obtain iron diselenide coated with polyethylenedioxythiophene.

[0043] The conductivity of the sample was tested using the four-probe method, and the conductivity of pure iron diselenide was found to be approximately 6.2 × 10⁻⁶. -3 Scm -1 The conductivity of the polyethylene dioxythiophene-coated iron diselenide prepared in Example 1 is approximately 1.3 S / cm. -1 .

[0044] The polyethylene dioxythiophene-coated iron diselenide prepared in Example 1 was used as the active material. It was mixed and ground into a uniform slurry in an N-methylpyrrolidone organic solvent at a ratio of 8:1:1 (active material: acetylene black: polyvinylidene fluoride). This slurry was coated onto copper foil, and after die-cutting, it was prepared as the negative electrode for a sodium-ion battery. The conductive agent was acetylene black, and the binder was polyvinylidene fluoride. Metallic sodium was used as the counter electrode, glass fiber as the separator, and sodium trifluoromethanesulfonate dissolved in diethylene glycol dimethyl ether as the electrolyte. The concentration of sodium trifluoromethanesulfonate was 1 mol / L. -1 Assembled into CR2032 button cells, at 0.1 A·g -1 Specific capacitance was tested at current densities of 0.1, 0.2, 0.5, 1.0, 2.0, 5, 10, and 15 A·g. -1 The rate performance of the battery was tested at different current densities; at 5 A·g -1 Cyclic performance was tested at a current density of 0.1 A·g; the results showed that the sodium-ion battery anode material prepared in this example has good electrochemical performance: at 0.1 A·g -1 It has a current density of 490.4 mAh·g -1 High specific capacity; at 15 A·g -1 At high current density, it has 294.2 mAh·g -1 Specific capacity; at 5A·g -1 At a current density of 403 mAh·g, after 5000 cycles, it still maintains a capacity of 403 mAh·g. -1 Specific capacity.

[0045] Example 2: A method for preparing polyethylene dioxythiophene coated iron diselenide, specifically completed according to the following steps:

[0046] First, 2 mmol of selenium powder was dissolved in 15 mL of hydrazine hydrate to obtain a hydrazine hydrate solution of selenium powder. 1 mmol of ferrous ammonium sulfate and 0.1 g of citric acid were dissolved in 30 mL of deionized water, and then added dropwise to the hydrazine hydrate solution of selenium powder, stirring thoroughly to obtain a mixed solution. The mixed solution was transferred to a 100 mL polytetrafluoroethylene (PTFE) reactor, which was then placed in an oven at 180°C for 12 hours. After the reaction was complete, the reactor was cooled to room temperature to obtain the reaction product. The reaction product was washed with water five times and with alcohol five times, and finally dried to obtain iron diselenide nanospheres.

[0047] 2. 100 mg of iron diselenide nanospheres and 125 μL of 3,4-ethylenedioxythiophene monomer were ultrasonically dispersed in 80 mL of deionized water. Then, 267.5 mg of ammonium persulfate was added to the mixture. The mixture was stirred continuously and reacted at room temperature for 10 h. After the reaction was completed, the product was collected, washed with water 5 times, and dried to obtain iron diselenide coated with polyethylenedioxythiophene.

[0048] The polyethylene dioxythiophene-coated iron diselenide prepared in Example 2 was used as the active material. It was mixed and ground into a uniform slurry in an N-methylpyrrolidone organic solvent at a ratio of 8:1:1 (active material: acetylene black: polyvinylidene fluoride). This slurry was coated onto copper foil, and after die-cutting, it was prepared as the negative electrode for a sodium-ion battery. The conductive agent was acetylene black, and the binder was polyvinylidene fluoride. Metallic sodium was used as the counter electrode, glass fiber as the separator, and sodium trifluoromethanesulfonate dissolved in diethylene glycol dimethyl ether as the electrolyte. The concentration of sodium trifluoromethanesulfonate was 1 mol / L. -1 Assembled into CR2032 button cells, at 0.1 A·g -1 Specific capacitance was tested at current densities of 0.1, 0.2, 0.5, 1.0, 2.0, 5, 10, and 15 A·g. -1 The rate performance of the battery was tested at different current densities; at 5 A·g -1 Cyclic performance was tested at a current density of 0.1 A·g; the results showed that the sodium-ion battery anode material prepared in this example has good electrochemical performance: at 0.1 A·g -1 It has a current density of 455.2 mAh·g -1 High specific capacity; at 15 A·g -1 At high current density, it has 195.0 mAh·g -1 Specific capacity; at 5A·g -1 At a current density of [value missing], after 5000 cycles, it still maintains 382 mAh·g. -1 Specific capacity.

[0049] Example 3: A method for preparing polyethylene dioxythiophene coated iron diselenide, specifically completed according to the following steps:

[0050] First, 2 mmol of selenium powder was dissolved in 15 mL of hydrazine hydrate to obtain a hydrazine hydrate solution of selenium powder. 1 mmol of ferrous ammonium sulfate and 0.1 g of citric acid were dissolved in 30 mL of deionized water, and then added dropwise to the hydrazine hydrate solution of selenium powder, stirring thoroughly to obtain a mixed solution. The mixed solution was transferred to a 100 mL polytetrafluoroethylene (PTFE) reactor, which was then placed in an oven at 180°C for 12 hours. After the reaction was complete, the reactor was cooled to room temperature to obtain the reaction product. The reaction product was washed with water five times and with alcohol five times, and finally dried to obtain iron diselenide nanospheres.

[0051] 2. 100 mg of iron diselenide nanospheres and 75 μL of 3,4-ethylenedioxythiophene monomer were ultrasonically dispersed in 80 mL of deionized water. Then, 160.5 mg of ammonium persulfate was added to the mixture. The mixture was stirred continuously and reacted at room temperature for 10 h. After the reaction was completed, the product was collected, washed with water 5 times, and dried to obtain iron diselenide coated with polyethylenedioxythiophene.

[0052] The polyethylene dioxythiophene-coated iron diselenide prepared in Example 3 was used as the active material. It was mixed and ground into a uniform slurry in an N-methylpyrrolidone organic solvent at a ratio of 8:1:1 (active material: acetylene black: polyvinylidene fluoride). This slurry was coated onto copper foil, and after die-cutting, it was prepared as the negative electrode for a sodium-ion battery. The conductive agent was acetylene black, and the binder was polyvinylidene fluoride. Sodium metal was used as the counter electrode, glass fiber as the separator, and sodium trifluoromethanesulfonate dissolved in diethylene glycol dimethyl ether was used as the electrolyte. The concentration of sodium trifluoromethanesulfonate was 1 mol / L. -1 Assembled into CR2032 button cells, at 0.1 A·g -1 Specific capacitance was tested at current densities of 0.1, 0.2, 0.5, 1.0, 2.0, 5, 10, and 15 A·g. -1 The rate performance of the battery was tested at different current densities; at 5 A·g -1 Cyclic performance was tested at a current density of 0.1 A·g; the results showed that the sodium-ion battery anode material prepared in this example has good electrochemical performance: at 0.1 A·g -1 It has a current density of 481.2 mAh·g -1 High specific capacity; at 15 A·g -1 At high current density, it has 180.4 mAh·g -1 Specific capacity; at 5A·g -1 At a current density of [value missing], after 5000 cycles, it still maintains 341 mAh·g. -1 Specific capacity.

[0053] Comparative Example 1: The preparation method of pure iron diselenide and its application as a sodium electrode is carried out according to the following steps:

[0054] First, 2 mmol of selenium powder was dissolved in 15 mL of hydrazine hydrate to obtain a hydrazine hydrate solution of selenium powder. 1 mmol of ferrous ammonium sulfate and 0.1 g of citric acid were dissolved in 30 mL of deionized water, and then added dropwise to the hydrazine hydrate solution of selenium powder. The mixture was stirred thoroughly to obtain a mixed solution. The mixed solution was transferred to a 100 mL polytetrafluoroethylene (PTFE) reactor, which was then placed in an oven at 180°C for 12 h. After the reaction was completed, the reactor was cooled to room temperature to obtain the reaction product. The reaction product was washed with water five times and with alcohol five times, and finally dried to obtain iron diselenide nanospheres.

[0055] Iron diselenide nanospheres prepared in Comparative Example 1 were used as the active material. They were mixed and ground into a uniform slurry in an N-methylpyrrolidone organic solvent at a ratio of 8:1:1 (active material: acetylene black: polyvinylidene fluoride). This slurry was coated onto copper foil, and after die-cutting, it was prepared as the negative electrode for a sodium-ion battery. The conductive agent was acetylene black, and the binder was polyvinylidene fluoride. Metallic sodium was used as the counter electrode, glass fiber as the separator, and sodium trifluoromethanesulfonate dissolved in diethylene glycol dimethyl ether as the electrolyte. The concentration of sodium trifluoromethanesulfonate was 1 mol / L. -1 Assembled into CR2032 button cells, at 0.1 A·g -1 Specific capacitance was tested at current densities of 0.1, 0.2, 0.5, 1.0, 2.0, 5, 10, and 15 A·g. -1 The rate performance of the battery was tested at different current densities; the test results showed that the electrochemical performance of the sodium-ion battery anode material prepared in this example was very poor: at 0.1 A·g -1 It has a current density of 476.9 mAh g -1 Specific capacity; at 15 A·g -1 At high current densities, the specific capacity is almost zero.

[0056] Figure 2 The figures are microscopic morphology images. In the figure, (a) is a scanning electron microscope image of pure iron diselenide, (b) is a scanning electron microscope image of iron diselenide coated with polyethylene dioxythiophene prepared in Example 1, and (c) is a transmission electron microscope image of iron diselenide coated with polyethylene dioxythiophene prepared in Example 1.

[0057] from Figure 2 As can be seen from the images, both the pure iron diselenide and the iron diselenide coated with polyethylene dioxythiophene have morphologies of approximately 500 nm, consisting of spheres formed by the accumulation of nanoparticles. The transmission electron microscope images show that polyethylene dioxythiophene fills the gaps between the particles and encapsulates the entire sphere.

[0058] Figure 3 The figures show XRD and Raman spectra. In the figure, (a) is the XRD spectrum of pure iron diselenide and iron diselenide coated with polyethylene dioxythiophene, and (b) is the Raman spectrum of pure iron diselenide and iron diselenide coated with polyethylene dioxythiophene. In the figure, 1 is pure iron diselenide and 2 is iron diselenide coated with polyethylene dioxythiophene prepared in Example 1.

[0059] from Figure 3 (a) It can be seen that since polyethylene dioxythiophene is amorphous, the XRD patterns of both correspond well to the standard card for iron diselenide; from Figure 3 (b) It can be seen that at 281cm -1 and 217cm -1The characteristic peaks at 1561, 1500, 1438, and 1274 cm⁻¹ correspond to the stretching vibrations of Fe-Se and Se-Se bonds in iron diselenide, respectively. -1 The characteristic peaks at that location are all related to the thiophene ring.

[0060] Figure 4 The figure shows the rate performance of pure iron diselenide and iron diselenide coated with polyethylene dioxythiophene. In the figure, A is pure iron diselenide and B is iron diselenide coated with polyethylene dioxythiophene prepared in Example 1.

[0061] from Figure 4 It can be seen that, due to the improved conductivity after optimization, the rate performance of ferric diselenide coated with polyethylene dioxythiophene is better than that of ferric diselenide.

[0062] Figure 5 Cyclic performance of ferric diselenide coated with polyethylene dioxythiophene prepared in Example 1;

[0063] from Figure 5 It can be seen that: at 5A·g -1 At a current density of 403 mAh·g, after 5000 cycles, it still maintains a capacity of 403 mAh·g. -1 Specific capacity.

Claims

1. A method for preparing polyethylene dioxythiophene coated iron diselenide, characterized in that... The preparation method is specifically carried out according to the following steps: I. Preparation of mixed solution: ① Dissolve selenium powder in hydrazine hydrate to obtain a selenium powder hydrazine hydrate solution; ② Dissolve ferrous ammonium sulfate and citric acid in deionized water, then add selenium powder dropwise to a hydrazine hydrate solution, and stir until homogeneous to obtain a mixed solution; 2. Pour the mixed solution into a hydrothermal reactor, and then carry out a hydrothermal reaction under high temperature and high pressure to obtain solid reaction product I; wash and dry solid reaction product I to obtain iron diselenide:

3. Iron diselenide and 3,4-ethylenedioxythiophene were ultrasonically dispersed in deionized water, and then ammonium persulfate was added. The mixture was reacted under stirring at room temperature to obtain solid reaction product II. Solid reaction product II was washed and dried to obtain iron diselenide coated with polyethylenedioxythiophene.

2. The preparation method of polyethylene dioxythiophene coated iron diselenide according to claim 1, characterized in that... The amount of selenium powder mentioned in step 1① is in the volume ratio of hydrazine hydrate to 2 mmol: (15 mL to 20 mL).

3. The preparation method of polyethylene dioxythiophene coated iron diselenide according to claim 1, characterized in that... The molar ratio of ferrous ammonium sulfate to selenium powder mentioned in step 1② is 1:

2.

4. The preparation method of polyethylene dioxythiophene coated iron diselenide according to claim 1, characterized in that... The mass ratio of ferrous ammonium sulfate to citric acid in step 1② is 1 mmol: 0.1 g.

5. The preparation method of polyethylene dioxythiophene coated iron diselenide according to claim 1, characterized in that... The ratio of the amount of ferrous ammonium sulfate to the volume of deionized water in step 1② is 1 mmol:(25 mL to 35 mL).

6. The method for preparing polyethylene dioxythiophene coated iron diselenide according to claim 1, characterized in that... The hydrothermal reaction temperature in step two is 120℃~240℃, and the hydrothermal reaction time is 6h~48h; the volume of the hydrothermal reactor liner in step two is 100mL.

7. The preparation method of polyethylene dioxythiophene coated iron diselenide according to claim 1, characterized in that... The mass ratio of iron diselenide to 3,4-ethylenedioxythiophene in step three is 100 mg:(50 μL~150 μL); the reaction time in step three is 8 h~10 h under stirring at room temperature.

8. The preparation method of polyethylene dioxythiophene coated iron diselenide according to claim 1, characterized in that... The mass ratio of ferric diselenide to ammonium persulfate in step three is 100:(150-300); the mass ratio of ferric diselenide to deionized water in step three is 100mg:(70mL-150mL).

9. The application of a polyethylene dioxythiophene-coated iron diselenide prepared by the preparation method according to claim 1, characterized in that... A type of polyethylene dioxythiophene-coated iron diselenide is used as the negative electrode in sodium-ion batteries.

10. The application of polyethylene dioxythiophene coated iron diselenide according to claim 9, characterized in that... The preparation method of the sodium-ion battery negative electrode is as follows: Polyethylene dioxythiophene coated iron diselenide is used as the active material, and it is added to N-methylpyrrolidone at a mass ratio of active material: conductive agent: binder of 8:1:

1. The mixture is stirred into a uniform slurry, and then coated onto copper foil to obtain the sodium-ion battery negative electrode; the conductive agent is acetylene black, and the binder is polyvinylidene fluoride.

Images