阅读说明：本技术 一种磷掺杂的异质镍钴硫化物复合材料及其制备方法与应用 (Phosphorus-doped heterogeneous nickel-cobalt sulfide composite material and preparation method and application thereof ) 是由 邹汉波 冯志伟 彭卓 陈江东 杨伟 陈胜洲 于 2021-01-06 设计创作，主要内容包括：本发明公开了一种磷掺杂的异质镍钴硫化物复合材料及其制备方法与应用。本发明通过将泡沫镍置于含硝酸钴-表面活性剂的甲醇-水溶液中,水热反应,反应后冷却、清洗、干燥,得到的生长钴前驱体的泡沫镍进行煅烧,得到负载四氧化三钴的泡沫镍；将其置于含乙酸镍和硫代乙酰胺的乙醇溶液中,进行水热反应,反应后冷却、清洗、干燥,获得异质镍钴硫化物纳米复合材料；接着,将其放在气流下游,在上游的位置放入次磷酸钠,在氮气中进行煅烧,自然冷却,得到磷掺杂的异质镍钴硫化物复合材料。该材料具有出色的导电性和优异的电化学性能,将其作为活性材料应用于超级电容器中,表现出极好的循环稳定性和较高的能量密度。(The invention discloses a phosphorus-doped heterogeneous nickel cobalt sulfide composite material and a preparation method and application thereof. Placing foamed nickel into a methanol-water solution containing cobalt nitrate-surfactant, carrying out hydrothermal reaction, cooling, cleaning and drying after the reaction, and calcining the obtained foamed nickel of the cobalt precursor to obtain foamed nickel loaded with cobaltosic oxide; placing the mixture into an ethanol solution containing nickel acetate and thioacetamide for hydrothermal reaction, cooling, cleaning and drying after the reaction to obtain the heterogeneous nickel-cobalt sulfide nano composite material; and then, placing the composite material at the downstream of the air flow, placing sodium hypophosphite at the upstream position, calcining in nitrogen, and naturally cooling to obtain the phosphorus-doped heterogeneous nickel-cobalt sulfide composite material. The material has excellent conductivity and excellent electrochemical performance, and shows excellent cycling stability and higher energy density when being used as an active material in a super capacitor.)

1. A preparation method of a phosphorus-doped heterogeneous nickel cobalt sulfide composite material is characterized by comprising the following steps:

1) placing the foamed nickel in a methanol-water solution containing cobalt nitrate-surfactant for hydrothermal reaction, cooling, cleaning and drying after the reaction to obtain foamed nickel of a cobalt precursor;

2) calcining the foamed nickel of the cobalt precursor obtained in the step 1) to obtain foamed nickel loaded with cobaltosic oxide;

3) placing the cobaltosic oxide-loaded foamed nickel obtained in the step 2) into an ethanol solution containing nickel acetate and thioacetamide for hydrothermal reaction, cooling, cleaning and drying to obtain a heterogeneous nickel-cobalt sulfide nano composite material;

4) placing the heterogeneous nickel cobalt sulfide nano composite material obtained in the step 3) at the downstream of the airflow, placing sodium hypophosphite at the upstream position, calcining in nitrogen, and naturally cooling to obtain a phosphorus-doped heterogeneous nickel cobalt sulfide composite material;

the surfactant in the step 1) is at least one of sodium dodecyl sulfate, polyvinylpyrrolidone and hexadecyltrimethylammonium bromide.

2. The method of preparing a phosphorus doped heterogeneous nickel cobalt sulfide composite material of claim 1 wherein:

the cobalt nitrate and the surfactant in the step 1) are mixed according to the mass ratio of (1-2): 1, proportioning;

the nickel acetate and the thioacetamide in the step 3) are mixed according to a molar ratio of 1: 1-6 parts by weight;

the amount of the sodium hypophosphite in the step 4) is 125-500 mg.

3. The method of preparing a phosphorus doped heterogeneous nickel cobalt sulfide composite material of claim 2 wherein:

the cobalt nitrate and the surfactant in the step 1) are mixed according to the mass ratio of (1.2-1.9) to 1;

the nickel acetate and the thioacetamide in the step 3) are mixed according to a molar ratio of 1: 3, proportioning.

4. The method of preparing a phosphorus doped heterogeneous nickel cobalt sulfide composite material of claim 1 wherein:

the methanol-water solution is methanol: and (3) water is 6-8: 1, compounding in proportion;

the dosage of the methanol-water solution is (cobalt nitrate + surfactant): methanol-water solution ═ 1 g: mixing in a ratio of 15-20 mL;

the ethanol solution in the step 3) is absolute ethanol.

5. The method of preparing a phosphorus doped heterogeneous nickel cobalt sulfide composite material of claim 1 wherein:

the hydrothermal reaction in the step 1) is carried out for 8-12 h at 160-200 ℃;

the drying in the step 1) is vacuum drying at 60-100 ℃ for 10-14 h;

the calcination in step 2) comprises the following specific steps: heating to 200-600 ℃ at a heating rate of 1-3 ℃/min, and keeping the temperature for 0.5-6 h;

the hydrothermal reaction in the step 3) is carried out for 1-10 h at 70-160 ℃;

the drying in the step 3) is vacuum drying at 60-100 ℃ for 10-14 h.

6. The method of preparing a phosphorus doped heterogeneous nickel cobalt sulfide composite material of claim 5 wherein:

the hydrothermal reaction in the step 1) is carried out for 10 hours at 180 ℃;

the drying in the step 1) is vacuum drying at 80 ℃ for 12 hours;

the calcination in step 2) comprises the following specific steps: heating to 200-400 ℃ at a heating rate of 2 ℃/min, and keeping the temperature for 1-3 h;

the hydrothermal reaction in the step 3) is carried out for 2-6 h at the temperature of 90-140 ℃;

the drying in step 3) is vacuum drying at 80 ℃ for 12 h.

7. The method of preparing a phosphorus doped heterogeneous nickel cobalt sulfide composite material of claim 1 wherein:

the cleaning in the step 1) is washing by using absolute ethyl alcohol and ultrapure water;

the cleaning in the step 3) is washing by using absolute ethyl alcohol and ultrapure water;

the calcination in the step 4) comprises the following specific steps: heating to 200-600 ℃ at a heating rate of 1-3 ℃/min, and keeping the temperature for 0.5-6 h.

8. A phosphorus-doped heterogeneous nickel cobalt sulfide composite material is characterized in that: obtained by the preparation method of any one of claims 1 to 7.

9. Use of the phosphorus doped heterogeneous nickel cobalt sulfide composite material of claim 8 in the preparation of a supercapacitor.

10. A supercapacitor, characterized by: a heterogeneous nickel cobalt sulfide composite material containing the phosphorous doped nickel cobalt sulfide composite material of claim 8.

Technical Field

The invention belongs to the field of materials, and particularly relates to a phosphorus-doped heterogeneous nickel cobalt sulfide composite material and a preparation method and application thereof.

Background

The super capacitor is one of important representatives of new energy storage devices, has the advantages of ultrahigh power density, rapid charge and discharge rate, excellent cycle performance, lower maintenance cost and the like, and becomes a bridge for connecting a battery and electric equipment. However, practical application of supercapacitors is still hampered by the lack of high performance electrode materials. Therefore, the design and research of a novel electrode material with high specific capacity and excellent electrochemical stability have important practical significance for replacing traditional energy sources by the super capacitor.

The transition metal sulfide has higher theoretical specific capacitance and rapid oxidation-reduction reaction rate, and gradually becomes an ideal electrode material of a super capacitor. However, in the long-term charge and discharge process, the transition metal sulfide electrode material is easy to undergo severe volume expansion, so that the reaction rate is reduced, the capacity attenuation and the cycling stability are reduced, and the wide application of the transition metal sulfide electrode material in the field of supercapacitors is severely limited.

The heterogeneous transition metal sulfide not only can utilize the synergistic effect between different metal atoms, but also can combine the redox reaction characteristics of two metal elements, thereby effectively improving the electrochemical performance of the material. In addition, the heterogeneous transition metal sulfide composite material with a special structure is constructed on the conductive substrate, so that the contact area of the active substance and the electrolyte can be increased, an effective electron/ion diffusion channel is provided, and the high energy density of the electrode is ensured.

The doping of the heteroatom with the transition metal sulfide can modify the electronic state of the raw material and increase the active sites of the electrode material. The phosphorus element has large atomic radius and strong electron supply capability, and can effectively adjust the electronic structure and improve the electrochemical performance when being doped into the composite electrode.

In view of the above, there is a need for a phosphorus-doped heterogeneous nickel cobalt sulfide composite material having excellent electrical conductivity and excellent electrochemical properties through a simple hydrothermal-roasting process.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a preparation method of a phosphorus-doped heterogeneous nickel cobalt sulfide composite material.

The invention also aims to provide the phosphorus-doped heterogeneous nickel cobalt sulfide composite material prepared by the preparation method.

The invention further aims to provide application of the phosphorus-doped heterogeneous nickel cobalt sulfide composite material.

The purpose of the invention is realized by the following technical scheme:

a preparation method of a phosphorus-doped heterogeneous nickel cobalt sulfide composite material comprises the following steps:

1) placing the foamed nickel in a methanol-water solution containing cobalt nitrate-surfactant for hydrothermal reaction, cooling, cleaning and drying after the reaction to obtain foamed nickel of a cobalt precursor;

2) calcining the foamed nickel of the cobalt precursor obtained in the step 1) to obtain foamed nickel loaded with cobaltosic oxide;

3) placing the cobaltosic oxide-loaded foamed nickel obtained in the step 2) into an ethanol solution containing nickel acetate and thioacetamide for hydrothermal reaction, cooling, cleaning and drying to obtain a heterogeneous nickel-cobalt sulfide nano composite material;

4) and (3) placing the heterogeneous nickel cobalt sulfide nano composite material obtained in the step 3) at the downstream of the airflow, placing sodium hypophosphite at the upstream position, calcining in nitrogen, and naturally cooling to obtain the phosphorus-doped heterogeneous nickel cobalt sulfide nano composite material.

The cobalt nitrate and the surfactant in the step 1) are preferably mixed according to the mass ratio of (1-2): 1, proportioning; more preferably, the weight ratio of (1.2-1.9) to (1); most preferably 1.45:1 by mass ratio.

The methanol-water solution is preferably methanol: and (3) water is 6-8: 1, compounding in proportion; more preferably methanol: water in volume ratio of 7: 1, compounding to obtain the product.

The methanol-water solution is only used as a reaction medium and does not participate in the reaction; the dosage of the catalyst is suitable for the full dissolution of each component to participate in the reaction, and the catalyst is preferably (cobalt nitrate + surfactant): methanol-water solution ═ 1 g: mixing in a ratio of 15-20 mL; more preferably (cobalt nitrate + surfactant): methanol-water solution ═ 1 g: mixing in a proportion of 16-17 mL.

The surfactant in step 1) is preferably at least one of sodium lauryl sulfate, polyvinylpyrrolidone and cetyltrimethylammonium bromide.

The hydrothermal reaction in the step 1) is preferably carried out at 160-200 ℃ for 8-12 h; more preferably at 180 ℃ for 10 h.

The washing described in step 1) is preferably washing with anhydrous ethanol and ultrapure water.

The drying in the step 1) is preferably carried out for 10-14 h at the temperature of 60-100 ℃ in vacuum; more preferably dried under vacuum at 80 ℃ for 12 h.

The specific steps of calcination described in step 2) are preferably as follows: heating to 200-600 ℃ at a heating rate of 1-3 ℃/min, and keeping the temperature for 0.5-6 h; more preferably as follows: heating to 200-400 ℃ at a heating rate of 2 ℃/min, and keeping the temperature for 1-3 h; most preferably as follows: the temperature is raised to 400 ℃ at the heating rate of 2 ℃/min and is kept for 2 h.

The nickel acetate and the thioacetamide in the step 3) are preferably mixed in a molar ratio of 1: 1-6 parts by weight; more preferably, the molar ratio of 1: 2-4 proportion; most preferably as follows: nickel acetate and thioacetamide in a molar ratio of 1: 3, proportioning.

The nickel acetate is preferably nickel acetate tetrahydrate.

The ethanol solution in the step 3) is absolute ethanol.

The absolute ethyl alcohol solution is used as a reaction medium and does not participate in the reaction; the dosage of the nickel oxide is suitable for the full dissolution of each component and the reaction of immersing the cobaltosic oxide-loaded foamed nickel.

The hydrothermal reaction in the step 3) is preferably carried out at 70-160 ℃ for 1-10 h; more preferably, the reaction is carried out for 2-6 h at the temperature of 90-140 ℃; most preferably at 120 ℃ for 2 h.

The washing in step 3) is preferably washing with anhydrous ethanol and ultrapure water.

The drying in the step 3) is preferably carried out for 10-14 h at the temperature of 60-100 ℃ in vacuum; more preferably dried under vacuum at 80 ℃ for 12 h.

The preferable dosage of the sodium hypophosphite in the step 4) is 125-500 mg, and the more preferable dosage is 175 mg.

The specific steps of calcination described in step 4) are preferably as follows: heating to 200-600 ℃ at a heating rate of 1-3 ℃/min, and keeping the temperature for 0.5-6 h; more preferably as follows: heating to 200-400 ℃ at a heating rate of 2 ℃/min, and keeping the temperature for 1-3 h; most preferably as follows: heating to 300 ℃ at the heating rate of 2 ℃/min, and keeping the temperature for 2 h.

A phosphorus-doped heterogeneous nickel cobalt sulfide composite material is obtained by the preparation method.

The phosphorus-doped heterogeneous nickel cobalt sulfide composite material is applied to the preparation of a super capacitor.

A super capacitor contains the phosphorus-doped heterogeneous nickel cobalt sulfide composite material.

Compared with the prior art, the invention has the following advantages and effects:

1. the heterogeneous composite material provided by the invention has excellent conductivity and excellent electrochemical performance, and shows excellent cycling stability and higher energy density when being applied to a super capacitor as an active material.

2. The product has a uniform nano-heterostructure; adopts a simple and convenient solvothermal method, and is easy for large-scale batch preparation.

Drawings

Fig. 1 is an SEM image of the heterogeneous nickel cobalt sulfide composite of example 1.

Fig. 2 is an SEM image of the phosphorus doped heterogeneous nickel cobalt sulfide composite of example 1.

Figure 3 is an XRD pattern of the hetero-nickel cobalt sulfide nanocomposite and the phosphorous doped hetero-nickel cobalt sulfide composite of example 1.

Fig. 4 is a cyclic voltammogram of a three-electrode system in which the heterogeneous nickel cobalt sulfide composite and the phosphorus-doped heterogeneous nickel cobalt sulfide composite of example 1 were directly assembled as a positive electrode.

Fig. 5 is a rate performance graph of a three-electrode system in which the phosphorus-doped heterogeneous nickel cobalt sulfide composite material in example 1 is directly assembled as a positive electrode.

Fig. 6 is a graph of power density versus energy density for a simulated cell assembled directly as the positive electrode with the phosphorus doped heterogeneous nickel cobalt sulfide composite of example 1.

Fig. 7 is an SEM image of the phosphorus doped heterogeneous nickel cobalt sulfide composite of example 2.

Fig. 8 is a constant current charging and discharging curve diagram of a three-electrode system assembled by directly using the phosphorus-doped heterogeneous nickel cobalt sulfide composite material as a positive electrode in example 2.

Fig. 9 is a rate performance graph of a three-electrode system in which the phosphorus-doped heterogeneous nickel cobalt sulfide composite in example 2 is directly assembled as a positive electrode.

Fig. 10 is a constant current charge and discharge curve diagram of a three-electrode system in which the phosphorus-doped heterogeneous nickel cobalt sulfide composite material in example 3 is directly assembled as a positive electrode.

Fig. 11 is an SEM image of the phosphorus doped heterogeneous nickel cobalt sulfide composite of example 4.

Fig. 12 is a constant current charge and discharge curve diagram of a three-electrode system in which the phosphorus-doped heterogeneous nickel cobalt sulfide composite material in example 4 is directly assembled as a positive electrode.

Fig. 13 is an SEM image of the phosphorous doped heterogeneous nickel cobalt sulfide composite of example 5.

Fig. 14 is a rate performance graph of a three-electrode system in which the phosphorus-doped heterogeneous nickel cobalt sulfide composite in example 5 was directly assembled as a positive electrode.

Fig. 15 is an SEM image of the phosphorus doped heterogeneous nickel cobalt sulfide composite of example 6.

Fig. 16 is a rate performance graph of a three-electrode system in which the phosphorus-doped heterogeneous nickel cobalt sulfide composite of example 6 was directly assembled as a positive electrode.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.

Example 1

(1) A preparation method of a phosphorus-doped heterogeneous nickel cobalt sulfide composite material comprises the following steps:

1) 1.45g of cobalt nitrate and 1g of sodium lauryl sulfate were dissolved in a mixed solution of 35mL of methanol and 5mL of water. After stirring to form a pink homogeneous solution, a piece of nickel foam (3 cm. times.5 cm) which had been washed several times with acetone, hydrochloric acid, and ultrapure water was immersed in the above solution, and then the mixed solution was transferred to a 50mL polytetrafluoroethylene liner and heated to 180 ℃ for 10 hours. After the reaction kettle is naturally cooled to room temperature, taking out the foamed nickel, sequentially washing the foamed nickel for a plurality of times by using absolute ethyl alcohol and ultrapure water, and then drying the foamed nickel in vacuum at the temperature of 80 ℃ for 12 hours to obtain foamed nickel loaded with a Co precursor;

2) transferring the Co precursor-loaded foamed nickel obtained in the step 1) into a muffle furnace, placing the muffle furnace in an air atmosphere, heating to 400 ℃ at a heating rate of 2 ℃/min, and preserving heat for 2h to obtain cobaltosic oxide nanoflower-loaded foamed nickel;

3) immersing the cobaltosic oxide-loaded foamed nickel obtained in the step 2) into 40mL of absolute ethanol solution containing 0.63g of nickel acetate tetrahydrate and 0.56g of thioacetamide, and then transferring the material into a 50mL high-pressure reaction kettle to perform constant-temperature reaction at 120 ℃ for 2 hours. After cooling, washing the foamed nickel for several times by ultrapure water and ethanol, and finally drying at 80 ℃ for 12 hours to obtain the heterogeneous nickel-cobalt sulfide nano composite material;

4) placing the heterogeneous nickel cobalt sulfide nano composite material obtained in the step 3) and 0.175g of sodium hypophosphite into the same quartz boat, placing the sodium hypophosphite upstream of the airflow, heating to 300 ℃ at the speed of 2 ℃/min under the nitrogen atmosphere, calcining for 2h, and naturally cooling to obtain the phosphorus-doped heterogeneous nickel cobalt sulfide nano composite material (P-Co sulfide)₃S₄@Ni₃S₄)。

(2) And (3) performance testing:

1) the SEM image of the heterogeneous nickel cobalt sulfide nanocomposite is shown in fig. 1, and the SEM image of the phosphorus doped heterogeneous nickel cobalt sulfide nanocomposite is shown in fig. 2.

Comparing fig. 1 and fig. 2, it can be seen that: the morphology of the product before and after phosphorus doping is not obviously changed and is represented by nanoflower with the diameter of about 3 mu m. However, the final phosphorus-doped heterogeneous nickel cobalt sulfide composite material nanometer petal is provided with a plurality of intricate and complex nanometer sheets which are connected with each other.

2) The XRD patterns of the heterogeneous nickel cobalt sulfide nanocomposite and the phosphorus doped heterogeneous nickel cobalt sulfide composite are shown in fig. 3.

As can be seen in fig. 3: the crystal structures of the products before and after phosphorus doping are basically consistent, and the product is mainly represented by Co₃S₄And Ni₃S₄And (5) structure.

3) The heterogeneous nickel cobalt sulfide nano composite material and the phosphorus-doped heterogeneous nickel cobalt sulfide composite material are directly used as a positive electrode, a Pt electrode is used as a counter electrode, an HgO/Hg electrode is used as a reference electrode, and a KOH aqueous solution with the concentration of 2mol/L is used as an electrolyte to assemble a three-electrode system. Cyclic voltammetry curves of a three-electrode system assembled by directly using the heterogeneous nickel cobalt sulfide nano composite material and the phosphorus-doped heterogeneous nickel cobalt sulfide composite material as positive electrodes are shown in fig. 4, and rate performance graphs (1A/g, 2A/g, 5A/g, 8A/g, 10A/g, 15A/g and 20A/g) are shown in fig. 5.

As can be seen from fig. 4: the limit current of the heterogeneous nickel cobalt sulfide composite material doped with phosphorus is doubled, and the area surrounded by the cyclic voltammetry curve is also greatly increased. Both sets of curves show only one set of redox peaks due to Ni²⁺And Co²⁺Similar redox reaction potentials and overlapping redox peaks.

As can be seen from fig. 5: the heterogeneous nickel cobalt sulfide composite material doped with phosphorus not only shows higher specific capacity, but also has more excellent rate capability. At a current density of 1A/g, 3614F/g high specific capacitance is shown, and after the current density is increased by 20 times, the capacity retention rate is still as high as 61%.

4) The heterogeneous nickel cobalt sulfide composite material doped with phosphorus is directly used as a positive electrode, and the load capacity of the heterogeneous nickel cobalt sulfide doped with phosphorus is 2mg/cm²The active carbon electrode is used as a negative electrode, and the loading capacity of the active carbon is 5mg/cm²A2 mol/L KOH aqueous solution is used as an electrolyte to assemble a simulation electrolytic cell, under the voltage range of 0-1.6V, a cyclic voltammetry test with the scanning rate of 5-50 mV/s and constant current charge and discharge tests under different current densities (1A/g, 2A/g, 5A/g, 8A/g, 10A/g, 15A/g and 20A/g) are respectively carried out, and a relation graph of power density and energy density shown in figure 6 is obtained according to the obtained specific capacitance.

As can be seen from fig. 6: the asymmetric super capacitor based on the phosphorus doped heterogeneous nickel cobalt sulfide composite material has the energy density of 72Wh/kg at the power density of 800W/kg, and the energy density is relatively high.

Example 2:

(1) a preparation method of a phosphorus-doped heterogeneous nickel cobalt sulfide composite material comprises the following steps:

1) the procedure was as in step 1) of example 1;

2) transferring the Co precursor-loaded foamed nickel obtained in the step 1) into a muffle furnace, placing the muffle furnace in an air atmosphere, heating to 400 ℃ at a heating rate of 2 ℃/min, and preserving heat for 2h to obtain cobaltosic oxide nanoflower-loaded foamed nickel;

3) immersing the cobaltosic oxide-loaded foamed nickel obtained in the step 2) into 40mL of absolute ethanol solution containing 0.63g of nickel acetate tetrahydrate and 0.56g of thioacetamide, and then transferring the material into a 50mL high-pressure reaction kettle to perform constant-temperature reaction at 120 ℃ for 2 hours. After cooling, washing the foamed nickel for several times by ultrapure water and ethanol, and finally drying at 80 ℃ for 12 hours to obtain the heterogeneous nickel-cobalt sulfide nano composite material;

4) putting the product obtained in the step 3) and 0.25g of sodium hypophosphite into the same quartz boat, putting the sodium hypophosphite at the upstream of the airflow, heating to 300 ℃ at the speed of 2 ℃/min in the nitrogen atmosphere, calcining for 2h, and naturally cooling to obtain the phosphorus-doped heterogeneous nickel cobalt sulfide composite material (P-Co-Ni-Co sulfide composite material)₃S₄@Ni₃S₄)。

(2) And (3) performance testing:

1) an SEM image of the phosphorus doped heterogeneous nickel cobalt sulphide composite is shown in figure 7.

As can be seen from fig. 7: increasing the amount of sodium hypophosphite, the phosphorus doped heterogeneous nickel cobalt sulphide composite still showed nanoflowers with a diameter of about 3 μm.

2) Constant current charge and discharge tests are carried out under different current densities (1A/g, 2A/g, 5A/g, 8A/g, 10A/g, 15A/g and 20A/g) to obtain a constant current charge and discharge curve (shown in figure 8) and a rate performance graph (shown in figure 9) of the phosphorus-doped heterogeneous nickel cobalt sulfide composite material.

As can be seen from fig. 8: the phosphorus-doped heterogeneous nickel cobalt sulfide composite material shows 2631F/g high specific capacity at the current density of 1A/g.

As can be seen from fig. 9: the phosphorus-doped heterogeneous nickel cobalt sulfide composite material still shows 61% of capacity retention rate under the high current density of 20A/g, and the composite material is proved to have good rate performance.

Example 3:

(1) a preparation method of a phosphorus-doped heterogeneous nickel cobalt sulfide composite material comprises the following steps:

1) the procedure was as in step 1) of example 1;

2) transferring the Co precursor-loaded foamed nickel obtained in the step 1) into a muffle furnace, placing the muffle furnace in an air atmosphere, heating to 400 ℃ at a heating rate of 2 ℃/min, and preserving heat for 2h to obtain cobaltosic oxide nanoflower-loaded foamed nickel;

3) immersing the cobaltosic oxide-loaded foamed nickel obtained in the step 2) into 40mL of absolute ethanol solution containing 0.63g of nickel acetate tetrahydrate and 0.56g of thioacetamide, and then transferring the material into a 50mL high-pressure reaction kettle to perform constant-temperature reaction at 120 ℃ for 2 hours. After cooling, washing the foamed nickel for several times by ultrapure water and ethanol, and finally drying at 80 ℃ for 12 hours to obtain the heterogeneous nickel-cobalt sulfide nano composite material;

4) placing the product obtained in step 3) and 0.175g of sodium hypophosphite in the same quartz boat, placing the sodium hypophosphite upstream of the gas flow, and performing reaction at 2 ℃/min in nitrogen atmosphereHeating to 300 ℃, calcining for 1h, and naturally cooling to obtain the phosphorus-doped heterogeneous nickel cobalt sulfide composite material (P-Co)₃S₄@Ni₃S₄)。

(2) And (3) performance testing:

1) constant current charge and discharge tests were performed at different current densities (1A/g, 2A/g, 5A/g, 8A/g, 10A/g, 15A/g, and 20A/g) to obtain constant current charge and discharge curves (as shown in FIG. 10) for the phosphorus-doped heterogeneous nickel cobalt sulfide composite material.

As can be seen from fig. 10: at a current density of 1A/g, there is a high specific capacitance of 3411F/g.

Example 4:

(1) a preparation method of a phosphorus-doped heterogeneous nickel cobalt sulfide composite material comprises the following steps:

1) the procedure was as in step 1) of example 1;

2) transferring the Co precursor-loaded foamed nickel obtained in the step 1) into a muffle furnace, placing the muffle furnace in an air atmosphere, heating to 400 ℃ at a heating rate of 2 ℃/min, and preserving heat for 2h to obtain cobaltosic oxide nanoflower-loaded foamed nickel;

3) immersing the cobaltosic oxide-loaded foamed nickel obtained in the step 2) into 40mL of absolute ethanol solution containing 0.63g of nickel acetate tetrahydrate and 0.56g of thioacetamide, and then transferring the material into a 50mL high-pressure reaction kettle to perform constant-temperature reaction at 120 ℃ for 2 hours. After cooling, washing the foamed nickel for several times by ultrapure water and ethanol, and finally drying at 80 ℃ for 12 hours to obtain the heterogeneous nickel-cobalt sulfide nano composite material;

4) putting the product obtained in the step 3) and 0.125g of sodium hypophosphite into the same quartz boat, putting the sodium hypophosphite upstream of the airflow, heating to 300 ℃ at the speed of 2 ℃/min under the nitrogen atmosphere, calcining for 2h, and naturally cooling to obtain the phosphorus-doped heterogeneous nickel cobalt sulfide composite material (P-Co nickel cobalt sulfide)₃S₄@Ni₃S₄)。

(2) And (3) performance testing:

1) an SEM image of the phosphorus doped heterogeneous nickel cobalt sulfide composite is shown in figure 11.

As can be seen from fig. 11: the phosphorous doped heterogeneous nickel cobalt sulfide composite still exhibited nanoflower about 3 μm in diameter with a reduced amount of sodium hypophosphite.

2) Constant current charge and discharge tests were performed at different current densities (1A/g, 2A/g, 5A/g, 8A/g, 10A/g, 15A/g, and 20A/g) to obtain constant current charge and discharge curves (as shown in FIG. 12) for the phosphorus-doped heterogeneous nickel cobalt sulfide composite material.

As can be seen from fig. 12: the phosphorus-doped heterogeneous nickel cobalt sulfide composite material has a high specific capacitance of 3404F/g at a current density of 1A/g.

Example 5:

(1) a preparation method of a phosphorus-doped heterogeneous nickel cobalt sulfide composite material comprises the following steps:

1) 1.45g of cobalt nitrate and 1g of polyvinylpyrrolidone (average molecular weight 24000) were dissolved in a mixed solution of 35mL of methanol and 5mL of water. After stirring to form a pink homogeneous solution, a piece of nickel foam (3 cm. times.5 cm) which had been washed several times with acetone, hydrochloric acid, and ultrapure water was immersed in the above solution, and then the mixed solution was transferred to a 50mL polytetrafluoroethylene liner and heated to 180 ℃ for 10 hours. After the reaction kettle is naturally cooled to room temperature, taking out the foamed nickel, sequentially washing the foamed nickel for a plurality of times by using absolute ethyl alcohol and ultrapure water, and then drying the foamed nickel in vacuum at the temperature of 80 ℃ for 12 hours to obtain foamed nickel loaded with a Co precursor;

2) transferring the Co precursor-loaded foamed nickel obtained in the step 1) into a muffle furnace, placing the muffle furnace in an air atmosphere, heating to 400 ℃ at a heating rate of 2 ℃/min, and preserving heat for 2h to obtain cobaltosic oxide-loaded foamed nickel;

3) immersing the cobaltosic oxide-loaded foamed nickel obtained in the step 2) into 40mL of absolute ethanol solution containing 0.63g of nickel acetate tetrahydrate and 0.56g of thioacetamide, and then transferring the material into a 50mL high-pressure reaction kettle to perform constant-temperature reaction at 120 ℃ for 2 hours. After cooling, washing the foamed nickel for several times by ultrapure water and ethanol, and finally drying at 80 ℃ for 12 hours to obtain the heterogeneous nickel-cobalt sulfide nano composite material;

4) putting the product obtained in the step 3) and 0.175g of sodium hypophosphite into the same quartz boat, putting the sodium hypophosphite upstream of the airflow, heating to 300 ℃ at the speed of 2 ℃/min under the nitrogen atmosphere, calcining for 2h, and naturallyCooling to obtain the phosphorus-doped heterogeneous nickel cobalt sulfide composite material (P-Co)₃S₄@Ni₃S₄)。

(2) And (3) performance testing:

1) an SEM image of the phosphorus doped heterogeneous nickel cobalt sulphide composite is shown in figure 13.

As can be seen from fig. 13: the phosphorus-doped heterogeneous nickel cobalt sulfide composite material shows a compact nanoneedle array structure by using polyvinylpyrrolidone as a surfactant.

2) Constant current charge and discharge tests were performed at different current densities (1A/g, 2A/g, 5A/g, 8A/g, 10A/g, 15A/g, and 20A/g) to obtain a rate capability graph for the phosphorus-doped heterogeneous nickel cobalt sulfide composite material (as shown in FIG. 14).

As can be seen from fig. 14: the phosphorus doped heterogeneous nickel cobalt sulfide composite material shows specific capacity of 1897F/g under the current density of 1A/g. Under the high current density of 20A/g, the capacity retention rate of 67% is still shown, and the composite material is proved to have good rate performance.

Example 6:

(1) a preparation method of a phosphorus-doped heterogeneous nickel cobalt sulfide composite material comprises the following steps:

1) 1.45g of cobalt nitrate and 1g of cetyltrimethylammonium bromide were dissolved in a mixed solution of 35mL of methanol and 5mL of water. After stirring to form a pink homogeneous solution, a piece of nickel foam (3 cm. times.5 cm) which had been washed several times with acetone, hydrochloric acid, and ultrapure water was immersed in the above solution, and then the mixed solution was transferred to a 50mL polytetrafluoroethylene liner and heated to 180 ℃ for 10 hours. After the reaction kettle is naturally cooled to room temperature, taking out the foamed nickel, sequentially washing the foamed nickel for a plurality of times by using absolute ethyl alcohol and ultrapure water, and then drying the foamed nickel in vacuum at the temperature of 80 ℃ for 12 hours to obtain foamed nickel loaded with a Co precursor;

2) transferring the Co precursor-loaded foamed nickel obtained in the step 1) into a muffle furnace, placing the muffle furnace in an air atmosphere, heating to 400 ℃ at a heating rate of 2 ℃/min, and preserving heat for 2h to obtain cobaltosic oxide-loaded foamed nickel;

3) immersing the cobaltosic oxide-loaded foamed nickel obtained in the step 2) into 40mL of absolute ethanol solution containing 0.63g of nickel acetate tetrahydrate and 0.56g of thioacetamide, and then transferring the material into a 50mL high-pressure reaction kettle to perform constant-temperature reaction at 120 ℃ for 2 hours. After cooling, washing the foamed nickel for several times by ultrapure water and ethanol, and finally drying at 80 ℃ for 12 hours to obtain the heterogeneous nickel-cobalt sulfide nano composite material;

4) putting the product obtained in the step 3) and 0.175g of sodium hypophosphite into the same quartz boat, putting the sodium hypophosphite upstream of the airflow, heating to 300 ℃ at the speed of 2 ℃/min under the nitrogen atmosphere, calcining for 2h, and naturally cooling to obtain the phosphorus-doped heterogeneous nickel cobalt sulfide composite material (P-Co nickel cobalt sulfide)₃S₄@Ni₃S₄)。

(2) And (3) performance testing:

1) an SEM image of the phosphorus doped heterogeneous nickel cobalt sulfide composite is shown in figure 15.

As can be seen from fig. 15: the phosphorus doped heterogeneous nickel cobalt sulphide composites exhibit an interconnected honeycomb structure using cetyltrimethylammonium bromide as surfactant.

2) Constant current charge and discharge tests were performed at different current densities (1A/g, 2A/g, 5A/g, 8A/g, 10A/g, 15A/g, and 20A/g) to obtain a rate capability graph for the phosphorus-doped heterogeneous nickel cobalt sulfide composite material (as shown in FIG. 16).

As can be seen from fig. 16: the phosphorus-doped heterogeneous nickel cobalt sulfide composite material shows the specific capacity of 1586F/g under the current density of 1A/g. Under the high current density of 20A/g, the capacity retention rate of 60% is still shown, and the composite material is proved to have good rate performance.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.