CN108773859B

CN108773859B - Vulcanized nano material and preparation method and application thereof

Info

Publication number: CN108773859B
Application number: CN201810823020.7A
Authority: CN
Inventors: 张莉; 韩欣茹; 陈群; 张宏
Original assignee: Anhui Normal University
Current assignee: Anhui Normal University
Priority date: 2018-07-25
Filing date: 2018-07-25
Publication date: 2021-05-14
Anticipated expiration: 2038-07-25
Also published as: CN108773859A

Abstract

The invention relates to an electrode nano material, and particularly discloses a preparation method of a vulcanized nano material, which comprises the following steps: (1) dissolving hexamethylenetetramine and a divalent nickel source in water, and heating and reacting under a continuous mixing condition to prepare a nano material precursor; (2) calcining the nano material precursor; (3) dispersing the calcined product in absolute ethyl alcohol containing thioacetamide, and heating to react. The method prepares the vulcanized nano material by using a hydrothermal method and combining the processes of calcining and vulcanizing, and the vulcanized nano material can be used as a capacitor electrode material and has excellent specific capacitance. Moreover, the preparation method is simple and controllable, does not need complex equipment and gas including processes, is low in cost and has high popularization and application values.

Description

Vulcanized nano material and preparation method and application thereof

Technical Field

The invention relates to an electrode nano material, in particular to a vulcanized nano material and a preparation method and application thereof.

Background

With the rapid increase of energy consumption, and the increasing impact of the use of fossil energy on environmental pollution and global climate, the search for efficient, green and sustainable energy storage systems is becoming an urgent need. In response to these challenges, researchers are motivated to pursue high-performance energy storage devices and technologies. Supercapacitors compare to other energy storage devices (e.g. Li)⁺Batteries, nickel metal hydride batteries), have high specific capacity, high cycling, and environmentally friendly characteristics, and thus are one of the most promising energy storage and conversion devices.

Supercapacitors can be classified into Electric Double Layer Supercapacitors (EDLCs) and pseudocapacitors, depending on the energy storage mechanism. Compared with the EDLC, the pseudocapacitor can form a series of rapid and reversible oxidation-reduction reactions when the surface of the electrode stores energy, and provides higher specific capacitance. The electrode material is one of the most important factors affecting the performance of the supercapacitor. In various supercapacitor electrode materials, materials with hollow structures attract great attention because of the fact that the materials have large surface areas, good surface permeability and short diffusion paths of ions and electrons, so that internal resistance is reduced and power capacity is improved.

Currently, many methods for the hollow structure of an electrode material for a supercapacitor have been developed, such as a self-assembly process, a template process, an ostwald ripening process, and a solvothermal process. Transition metal sulfide materials have recently received attention in the category of electrode materials for use in supercapacitors. When the ternary transition metal sulfide and the binary transition metal sulfide are applied to a super capacitor, compared with the traditional corresponding transition metal oxide, the ternary transition metal sulfide and the binary transition metal sulfide have the characteristics of excellent specific capacitance, stability, rate capability and the like.

Therefore, how to obtain a transition metal sulfide material with a hollow structure to obtain an electrode material with excellent specific capacitance is a hot spot of current research.

Disclosure of Invention

The invention aims to provide a vulcanized nano material as well as a preparation method and application thereof. Moreover, the preparation method is simple and controllable, does not need complex equipment and gas including processes, is low in cost and has high popularization and application values.

In order to achieve the above object, the present invention provides a method for preparing a vulcanized nanomaterial, the method comprising the steps of: (1) dissolving hexamethylenetetramine and a divalent nickel source in water, and heating and reacting under a continuous mixing condition to prepare a nano material precursor; (2) calcining the nano material precursor; (3) dispersing the calcined product in absolute ethyl alcohol containing thioacetamide, and heating to react.

The invention also provides a vulcanized nanomaterial prepared according to the preparation method.

Furthermore, the present invention provides the use of a sulphided nanomaterial according to the preceding description as an electrode material.

According to the technical scheme, the method prepares the vulcanized nano material by combining a hydrothermal method with calcination and vulcanization processes, and the vulcanized nano material can be used as a capacitor electrode material and has excellent specific capacitance. Moreover, the preparation method is simple and controllable, does not need complex equipment and gas including processes, is low in cost and has high popularization and application values.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a microscopic view of the carbon spheres of preparation example 1: (a) respectively showing a low-power scanning electron microscope image and a high-power transmission electron microscope image of the carbon sphere;

FIG. 2 shows NiCo₂(OH)₆Detection profile of/C product: (a) and (b) are NiCo obtained in example 1₂(OH)₆Low power scanning electron microscope image and high power transmission electron microscope image of/C product;

FIG. 3 is NiCo₂O₄Detection of hollow spheres: (a) and (b) are NiCo obtained in example 1₂O₄Low power scanning electron microscope image and high power transmission electron microscope image; (c) and (d) are NiCo obtained in example 1₂O₄EDX and X-ray powder diffractograms of;

FIG. 4 is a detection diagram of Ni-Co-S hollow spheres: (a) and (b) are respectively a low power scanning electron microscope image and a high power transmission electron microscope image of the Ni-Co-S obtained in the example 1; (c) and (d) EDX and X-ray powder diffractograms of the Ni-Co-S obtained in example 1; (e) and (f) are a CV diagram and a constant current charge-discharge diagram of the Ni-Co-S obtained in example 1, respectively; (g) and (h) are a rate performance graph and an EIS graph of the Ni-Co-S obtained in the example 1 respectively;

FIG. 5 shows Ni (OH)₂Detection pattern of/C: (a) and (b) are respectively Ni (OH) obtained in example 2₂Low power scanning electron microscope image and high power transmission electron microscope image of/C product;

fig. 6 is a detection diagram of NiO hollow spheres: (a) and (b) are respectively a low-power scanning electron microscope image and a high-power transmission electron microscope image of the NiO obtained in the example 2; (c) and (d) are respectively EDX diagram and X-ray powder diffraction diagram of NiO obtained in example 2;

FIG. 7 is a detection diagram of Ni-S hollow spheres: (a) is a low-power scanning electron microscope image of Ni-S obtained in example 2; (b) and (c) EDX and X-ray powder diffraction patterns of Ni-S obtained in example 2, respectively; (d) and (e) a CV diagram and a constant current charge/discharge diagram of Ni-S obtained in example 2; (f) an EIS diagram of the Ni-S obtained in example 2;

FIG. 8 shows NiCo obtained in example 3₂(OH)₆Low power scanning electron microscope image of the product;

FIG. 9 shows NiCo from example 3₂O₄Detection chart of (2): (a) is NiCo obtained in example 3₂O₄Low power scanning electron microscope images of; (b) is NiCo obtained in example 3₂O₄X-ray powder diffractogram of (a);

FIG. 10 is a graph of the detection of Ni-Co-S nanomaterials from example 3: (a) is a low power scanning electron micrograph of Ni-Co-S obtained in example 3; (b) is the X-ray powder diffraction pattern of Ni-Co-S obtained in example 3; (c) and (d) are a CV diagram and a constant current charge-discharge diagram of the Ni-Co-S obtained in example 3; (e) an EIS diagram of the Ni-Co-S obtained in example 3 is shown.

FIG. 11 is NiCo₂O₄Performance diagram of hollow spheres as electrode material when applied to a three-electrode body: (a) and (b) NiCo obtained in comparative example 1₂O₄A CV diagram and a constant current charge-discharge diagram of the hollow sphere; (c) NiCo obtained in comparative example 1₂O₄EIS diagram of hollow spheres;

FIG. 12 shows Co in comparative example 2₃O₄Detection of hollow spheres: (a) co obtained for comparative example 2₃O₄Low power scanning electron microscope images of; (b) co obtained for comparative example 2₃O₄X-ray powder diffractogram of (a);

FIG. 13 is a detection chart of Co-S hollow spheres: (a) is a macroscopic scanning electron microscope image of Co-S obtained in comparative example 2; (b) is the X-ray powder diffraction pattern of Co-S obtained in comparative example 2; (c) and (d) are a CV diagram and a constant current charge-discharge diagram of Co-S obtained in comparative example 2, respectively; (e) is an EIS diagram of Co-S obtained in comparative example 2.

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The invention provides a preparation method of a vulcanized nano material, which comprises the following steps: (1) dissolving hexamethylenetetramine and a divalent nickel source in water, and heating and reacting under a continuous mixing condition to prepare a nano material precursor; (2) calcining the nano material precursor; (3) dispersing the calcined product in absolute ethyl alcohol containing thioacetamide, and heating to react.

In the above technical solution, the concentration of the divalent nickel ions in water can be adjusted in a wide range, and in order to obtain the vulcanized nanomaterial with excellent specific capacitance and controllable morphology, the concentration of the divalent nickel ions in the solution is preferably 0.002-0.010 mol/L.

Meanwhile, the molar ratio of the divalent nickel ions to the hexamethylenetetramine can be adjusted in a wide range, so that the vulcanized nano material with excellent specific capacitance and controllable appearance can be obtained. In order to increase the yield of the target substance, it is preferable that the molar ratio of the divalent nickel ion to hexamethylenetetramine is 1: 0.5-3.

In addition, the addition amounts of the absolute ethyl alcohol, the calcined product and thioacetamide in the step (3) can be adjusted within a wide range, and in order to obtain the vulcanized nanomaterial with excellent specific capacitance and controllable morphology, it is preferable that in the step (3), the addition amount of the calcined product is 0.05 to 0.2mmol and the addition amount of the thioacetamide is 0.15 to 0.3mmol relative to 20mL of the absolute ethyl alcohol.

In order to increase the specific capacitance of the material, in a preferred embodiment of the present invention, a divalent cobalt source is further added to the water in step (1).

Furthermore, in order to make the morphology of the material more controllable and increase the specific surface area of the material, thereby obtaining the vulcanized nanomaterial with excellent specific capacitance, in a more preferred embodiment of the invention, preferably, citrate is further added into the water in the step (1). In this case, a vulcanized nanomaterial with stacked nanosheets can be obtained.

In addition, in order to increase the specific surface area, permeability and specific capacitance of the material, preferably, carbon spheres are further added to the water in step (1), so that the nanomaterial is accumulated on the surface of the carbon spheres, the morphology of the material is more controllable, and in the subsequent calcination process, the carbon spheres can be removed to obtain a hollow vulcanized nanomaterial, thereby further increasing the specific capacitance of the material.

Of course, one of the divalent cobalt source, the carbon spheres and the citrate is added into the water in the step (1), or two of the divalent cobalt source, the carbon spheres and the citrate can be added into the water in pairs, and the specific capacitance of the material can be improved to a certain extent.

The amount of the divalent cobalt source, the carbon spheres and the citrate added into the water in the step (1) can be selected in a wide range, and preferably, in order to obtain the vulcanized nano-material with controllable morphology and excellent specific capacitance performance, the molar ratio of the divalent nickel source, the divalent cobalt source, the hexamethylenetetramine and the citrate is preferably 1: 0-2: 0.5-3: 0-0.3.

In order to obtain the vulcanized nano material with controllable morphology and excellent specific capacitance performance, more preferably, the molar ratio of the divalent nickel source to the divalent cobalt source to the hexamethylenetetramine to the citrate is 1: 1-2: 0.75-2.5: 0.125-0.25.

In addition, in the above technical solution, the amount of the carbon spheres can be selected from a wide range, and preferably, the amount of the carbon spheres is 0 to 50mg relative to 1mmol of the divalent nickel source.

The conditions of the heating reaction in step (1) can be adjusted within a wide range, and in order to obtain the vulcanized nanomaterial with controllable morphology and excellent specific capacitance, the conditions of the heating reaction in step (1) preferably include: the temperature is 80-95 ℃ and the time is 4-8 h.

Meanwhile, the calcination conditions in step (2) can be adjusted within a wide range, and in order to obtain a vulcanized nanomaterial with controllable morphology and excellent specific capacitance, the calcination conditions in step (2) preferably include: the temperature is 300-500 ℃ and the time is 1-4 h.

The dispersion mode of the calcined product in step (3) can be selected from a wide range, such as stirring, shaking, ultrasound, etc., and the present invention can be implemented as long as the mixed system is kept in a non-static state. In order to obtain the vulcanized nanomaterial with uniform shape and size, the dispersion mode in the step (3) is preferably ultrasonic dispersion.

In order to obtain the vulcanized nano material with uniform shape and size, more preferably, the ultrasonic dispersion time is 5-60min, and the ultrasonic frequency is 30-50 kHZ.

The heating reaction conditions in step (3) can be adjusted within a wide range, and in order to obtain a vulcanized nanomaterial with controllable morphology and excellent specific capacitance performance, in a preferred embodiment of the invention, the heating reaction conditions in step (3) comprise: the temperature is 120-190 ℃ and the time is 10-14 h.

In the technical scheme, the carbon spheres are the carbon nanospheres, and the carbon spheres serve as templates to play a role of supporting frames in the reaction process and can be removed through calcination, so that the reaction process is simpler and more controllable. Wherein the nanocarbon spheres can be obtained by a variety of preparation methods, such as the chemical vapor deposition method disclosed in Carbon,2005,43:1944-1953, published by the Large-scale synthesis and characterization of Carbon spheres prepared by the chemical vapor deposition of hydrocarbons, Y.Z.jin, C.Gao, W.K.Hsu, Y.Zhu, D.R.M.Walton; the template method disclosed in adv.mater, 2002,19: 1390-; a method for lysing a carbon source as disclosed in Solid State Commun, 2004,131:749-752, published by A self-generated template to hollow carbon nanotubes in a short time, G.Zou, D.Yu, J.Lu, D.Wang, Y.Qian; the hydrothermal method disclosed in Colloidal carbon spheres and the core/shell structures with noble-metal nanoparticles, published in X.M.Sun, Y.D.Li, and described in Angew.chem.2004,116,607-611, the carbon spheres obtained by the above method have similar properties and states, and can be used as the carbon sphere template of the present invention.

In a preferred embodiment of the present invention, the hydrothermal method is preferably used to synthesize nanocarbon spheres because of its high purity, controllable shape and size, and low running cost.

In order to further obtain high-purity carbon spheres with controllable shape and size and reduce preparation cost, preferably, the hydrothermal method is performed by the following steps: dissolving cetyl trimethyl ammonium bromide and glucose into water, and then reacting at 160-180 ℃ for 10-14h to obtain a brown product; wherein, relative to 20mL of water, the dosage of the hexadecyl trimethyl ammonium bromide is 0.04-0.08g, and the dosage of the glucose is 1.5-2.5 g.

In order to further reduce impurities and to be more beneficial to obtaining an electrode material with high specific surface area, low density, good permeation and excellent electrochemical performance when subsequently preparing the Ni-Co-S/Ni-S/Co-S hollow nanospheres, the hydrothermal method preferably further comprises washing the brown product with deionized water and/or absolute ethyl alcohol for 2-6 times, and drying in an oven at 50-70 ℃ to obtain nano carbon sphere powder.

In the above technical solutions, many choices may exist for the divalent nickel source, as long as it can effectively ionize divalent nickel ions in an aqueous solution, which meets the requirements of the present invention. In order to improve reaction efficiency and reduce preparation cost, it is preferable that the divalent nickel source is NiSO₄、Ni(NO₃)₂、NiCl₂、NiBr₂And NiAc₂One or more of (a).

In the above technical solutions, many choices may exist for the divalent cobalt source, as long as it can effectively ionize divalent cobalt ions in an aqueous solution, which meets the requirements of the present invention. In order to improve reaction efficiency and reduce preparation cost, it is preferable that the divalent cobalt source is CoSO₄、Co(NO₃)₂、CoCl₂、CoBr₂And CoAc₂One or more of (a).

For citrate, in order to improve the preparation efficiency and reduce the preparation cost, preferably, the citrate is sodium citrate and/or potassium citrate.

In the above technical solution, the water may be selected from deionized water, ultrapure water, primary distilled water, double distilled water, and the like, and any water used in conventional experiments can meet the requirements of the present invention, and is not described herein again.

In addition, the addition modes of the components are selected in various ways, one substance is added after being dissolved, and the other substance can be added at the same time, and the substances can be continuously mixed and dissolved, and the modes are changed without influencing the essential effect of the invention.

In addition, the continuous mixing mode can be selected by those skilled in the art within a wide range, such as stirring with a stirring rod, magnetic stirring, ultrasonic mixing, shaking and the like, and the invention can be realized as long as the liquid is continuously in a non-static state. In the examples which follow, this is carried out by means of magnetic stirring.

In addition, the heating method of the present invention can be selected in a wide range, and a water bath, an oil bath, a thermostat, an incubator, an oven, a reaction kettle, etc. can be selected, so long as the reaction system meets the temperature requirement of the present invention, which is previously required, the present invention can be realized.

Preferably, the vulcanized nano material is a hollow spherical Ni-Co-S hollow sphere.

The vulcanized nano material prepared by the method is used as an electrode material of a super capacitor, and the application process comprises the following steps: the obtained vulcanized nano material is manufactured into an electrode to be applied to three electrodes, wherein the vulcanized nano material is used as an active working electrode, a Pt wire is used as a counter electrode, an Hg/HgO electrode is used as a reference electrode, and 3mol/L potassium hydroxide solution is used as electrolyte. The invention is applied to the super capacitor and has excellent charge-discharge coulombic effect and larger specific capacitance.

The present invention will be described in detail below by way of examples. In the following examples, the electrochemical performance of the supercapacitor was characterized by means of tests such as Cyclic Voltammetry (CV) described in Applied Surface Science,2018,434: 861-.

Preparation example 1

Weighing 0.05g of hexadecyl trimethyl ammonium bromide (CTAB) and dissolving in 20mL of deionized water, adding 2g of glucose under magnetic stirring, stopping stirring after the solution is completely dissolved, pouring the solution into a 25mL reaction kettle, putting the reaction kettle into an oven, heating to 170 ℃, reacting for 12h, cooling to room temperature, centrifuging to obtain a precipitate, washing with deionized water and absolute ethyl alcohol for several times respectively, and drying in a vacuum drying oven at 60 ℃ to constant weight to obtain the carbon spheres.

The microscopic display of the carbon sphere is shown in fig. 1, which can be seen from fig. 1, wherein the macroscopic scanning electron microscope image of the carbon sphere is shown in fig. 1 (a); a high power transmission electron micrograph of the carbon sphere is shown in fig. 1 (b); as can be seen from fig. 1(a) and 1(b), the carbon sphere templates are solid spheres with uniform size, about 800nm in diameter, and independent of each other.

Preparation example 2

Dissolving 0.04g of hexadecyl trimethyl ammonium bromide and 1.5g of glucose into 20mL of water, and then reacting for 14h at 160 ℃ to obtain a brown product; and then washing the brown product with deionized water and absolute ethyl alcohol for 3 times, and drying in an oven at 50 ℃ to obtain nano carbon sphere powder.

Preparation example 3

Dissolving 0.08g of hexadecyl trimethyl ammonium bromide and 2.5g of glucose into 20mL of water, and then reacting at 180 ℃ for 10 hours to obtain a brown product; and then washing the brown product with deionized water and absolute ethyl alcohol for 6 times, and drying in an oven at 70 ℃ to obtain nano carbon sphere powder.

The properties of the nanocarbon spheres prepared in preparation examples 2 and 3 were examined to be similar to those of preparation example 1.

Example 1

Adding 20mg of the carbon spheres obtained in the preparation example 1 into a solution containing 40mL of deionized water, 0.08mmol of nickel nitrate hexahydrate and 0.16mmol of cobalt nitrate hexahydrate, carrying out ultrasonic treatment for 10min, adding 0.2mmol of Hexamethylenetetramine (HMTA) and 0.02mmol of sodium citrate (TSC) under stirring, and continuing to stir for 60min to obtain a uniform solution; transferring the solution into a 50mL round-bottom flask, carrying out oil bath hydrothermal reaction at 90 ℃ for 4h to prepare a nano material precursor NiCo₂(OH)₆/C；

The precursor of the nano material is washed, dried and then calcined in a muffle furnace at 500 ℃ to remove the template, thus obtaining the hollowNiCo₂O₄；

Mixing the hollow NiCo₂O₄Adding 0.075mmol of Thioacetamide (TAA) and 20mL of absolute ethyl alcohol into a solution, and performing ultrasonic treatment for 5min to obtain a uniform solution; transferring the solution into a reaction kettle with a Teflon coating, and reacting for 12 hours in an oven by using the solvothermal temperature of 170 ℃; and washing, centrifuging and drying the obtained black powder to obtain the Ni-Co-S hollow sphere.

NiCo₂(OH)₆The detection pattern of the/C product is shown in FIG. 2, wherein FIG. 2(a) is a low-power scanning electron micrograph; NiCo₂(OH)₆High power transmission electron micrograph of/C product FIG. 2 (b); as can be seen from FIGS. 2(a) and 2(b), NiCo₂O₄The precursor of the hollow sphere is a solid sphere with a sheet structure and uniform size, and the diameter of the solid sphere is about 900 nm.

NiCo₂O₄The detection pattern of the hollow sphere is shown in FIG. 3, in which NiCo₂O₄The macroscopic scanning electron micrograph of the hollow sphere is shown in FIG. 3 (a); NiCo₂O₄A high power transmission electron micrograph of the hollow sphere is shown in fig. 3 (b); NiCo₂O₄The EDX map of the hollow spheres is shown in fig. 3 (c); NiCo₂O₄The X-ray powder diffraction pattern of the hollow sphere is shown in fig. 3 (d); as can be seen from FIGS. 3(a) and 3(b), NiCo₂O₄The hollow spheres are hollow spheres with sheet structures and uniform sizes, and are about 900 nm; FIG. 3(c) shows that the ratio of the elements Ni, Co, O is close to 1:2:4, and NiCo₂O₄Substance anastomosis; FIG. 3(d) shows NiCo₂O₄X-ray powder diffraction pattern of hollow spheres with NiCo₂O₄(JCPDS No. 20-0781).

The detection picture of the Ni-Co-S hollow sphere is shown in figure 4, wherein the macroscopic scanning electron microscope picture of the Ni-Co-S hollow sphere is shown in figure 4 (a); FIG. 4(b) is a high-power transmission electron micrograph of the Ni-Co-S hollow sphere; EDX of the Ni-Co-S hollow sphere is shown in FIG. 4 (c); the X-ray powder diffractogram of the Ni-Co-S hollow spheres is shown in FIG. 4 (d); CV diagram of Ni-Co-S hollow sphere is shown in FIG. 4 (e); the constant current charge-discharge diagram of the Ni-Co-S hollow sphere is shown in FIG. 4 (f); the multiplying power performance diagram of the Ni-Co-S hollow sphere is shown in figure 4 (g); EIS diagram of Ni-Co-S hollow sphere is shown in FIG. 4 (h); as can be seen from FIGS. 4(a) and 4(b), the Ni-Co-S hollow coreThe spheres are hollow spheres with a surface rice grain structure and uniform size, and are about 900 nm; FIG. 4(c) shows that the ratio of Ni, Co, S elements is close to 1:3:5, and NiCo₂S₄/Co₉S₈Mixing and matching; FIG. 4(d) is an X-ray powder diffraction pattern of Ni-Co-S hollow spheres, and NiCo₂S₄(JCPDS No.20-0782)、Co₉S₈(JCPDS No. 19-0364); as can be seen from FIG. 4(e), FIG. 4(F) and FIG. 4(h), when the Ni-Co-S hollow sphere is applied to three electrodes as an electrode material, the specific capacitance of the invented material reaches 2210F/g at a current density of 1A/g; FIG. 4(g) shows that the Ni-Co-S hollow sphere has excellent rate performance when being applied to a three-electrode as an electrode material; FIG. 4(h) shows the impedance spectrum of a Ni-Co-S hollow sphere as an electrode material applied to three electrodes, and it can be observed from the curve that a small semicircle with a diameter of charge transfer resistance (denoted as Rct) appears in the high frequency region; in a low frequency region, a straight line with a larger slope appears, the part of the straight line is attributed to the diffusion impedance (marked as W) of the electrolyte, and the intercept between the high frequency region and a real axis represents the solution resistance (marked as Rs); through analysis, the radius of the Ni-Co-S hollow sphere electrode material in the high-frequency region is very small, which shows that the resistance of the Ni-Co-S hollow sphere electrode material is small; the curve in the low frequency region is relatively inclined, which shows that the electrode material is an ideal electrode material of the super capacitor.

When the electrode material is applied to a super capacitor, the resistance of impedance detection is one of factors influencing electrochemical performance. The impedance diagram generally consists of a semicircle of a high-frequency region and a straight line of a low-frequency region, the vulcanized material disclosed by the invention has a semicircle with a smaller radius in the high-frequency region, and the material has lower charge transfer resistance, the low charge transfer resistance can be attributed to the high conductivity of the vulcanized material, and the high conductivity promotes the rapid transfer of charges in the charging and discharging processes, so that the material has better rate performance; in addition, the vulcanized material of our invention has a straight line with a larger slope in the low frequency region, which proves that it has the highest capacitance performance.

Example 2

20mg of the carbon spheres of preparation example 1 were added to a beaker containing 40mL of deionized water and 0.4mmol of nickel nitrate hexahydrate in solutionPerforming ultrasonic treatment for 30min, adding 0.3mmol HMTA and 0.1mmol TSC under stirring, and continuing stirring for 30min to obtain a uniform solution; transferring the solution into a 50mL round-bottom flask, and carrying out hydrothermal reaction for 5h at 90 ℃ by using an oil bath to obtain black powder Ni (OH)₂C; washing and drying the obtained black powder, and then calcining the black powder in a muffle furnace at 300 ℃ to remove a template to obtain a hollow NiO precursor;

adding 0.16mmol of the obtained hollow NiO precursor into a solution containing 0.16mmol of TAA and 20mL of absolute ethyl alcohol, and carrying out ultrasonic treatment for 10min to obtain a uniform solution; transferring the solution into a reaction kettle with a Teflon coating, and reacting in an oven at the temperature of 170 ℃ for 11h by using solvothermal reaction to obtain black powder; and washing, centrifuging and drying the black powder to obtain the Ni-S hollow sphere.

Ni(OH)₂The detection of/C is shown in FIG. 5, wherein Ni (OH)₂FIG. 5(a) is a scanning electron micrograph of,/C; ni (OH)₂High power transmission electron micrograph of/C product see FIG. 5 (b); as can be seen from fig. 5(a) and 5(b), the precursor of the NiO hollow sphere is a solid sphere with a sheet structure and uniform size, and is about 900 nm.

The detection diagram of the NiO hollow spheres is shown in fig. 6, wherein the macroscopic scanning electron microscope diagram of the NiO hollow spheres is shown in fig. 6 (a); a high-power transmission electron micrograph of the NiO hollow sphere is shown in FIG. 6 (b); the EDX diagram of the NiO hollow spheres is shown in FIG. 6 (c); the X-ray powder diffraction pattern of the NiO hollow spheres is shown in fig. 6 (d); as can be seen from fig. 6(a) and 6(b), the NiO hollow spheres are hollow spheres with a sheet structure and uniform size, and are about 900 nm; FIG. 6(c) shows that the ratio of the elements Ni, O is close to 1:1, consistent with the NiO species; FIG. 6(d) is an X-ray powder diffraction pattern of a NiO hollow sphere, which coincides with NiO (JCPDS No. 44-1159).

The detection picture of the Ni-S hollow sphere is shown in FIG. 7, wherein the macroscopic scanning electron microscope picture of the Ni-S hollow sphere is shown in FIG. 7 (a); EDX of Ni-S hollow spheres is shown in FIG. 7 (b); the X-ray powder diffraction pattern of the Ni-S hollow spheres is shown in FIG. 7 (c); the CV diagram of the Ni-S hollow sphere is shown in FIG. 7 (d); the constant current charge-discharge diagram of the Ni-S hollow sphere is shown in FIG. 7 (e); the EIS diagram of the Ni-S hollow sphere is shown in FIG. 7 (f); as can be seen from FIG. 7(a), the Ni-S hollow spheres are rice-grain-shaped hollow spheres with relatively uniform size, about 900 nm; FIG. 7(b) shows that the ratio of the elements Ni, S is close to 1:1, which coincides with NiS; drawing (A)7(c) is an X-ray powder diffraction pattern of the Ni-S hollow sphere, and is consistent with NiS (JCPDS No.02-1280) and NiO (JCPDS No. 44-1159); as can be seen from FIGS. 7(d), 7(e) and 7(F), when Ni-S hollow spheres are used as the electrode material in three electrodes, the specific capacitance of the invented material reaches 1592F/g at a current density of 1A/g. FIG. 7(f) is an impedance spectrum of a Ni-S hollow sphere as an electrode material applied to a three-electrode, and it can be observed from the graph that the radius of the semicircle appearing in the high frequency region is relatively large, which shows that the resistance of the Ni-S hollow sphere electrode material is slightly larger than that of example 1; but the straight line inclination in the low frequency region is small compared to Ni-Co-S, compared to Co-S, NiCo₂O₄The material is large, which shows that the material is superior to Co-S, NiCo when being used as the electrode material of the super capacitor₂O₄An electrode material.

Example 3

Ni-Co-S sulfide nanomaterial was prepared as in example 1, except that no carbon spheres were added.

Corresponding NiCo₂(OH)₆The macroscopic scanning electron micrograph of the product is shown in FIG. 8; as can be seen in FIG. 8, NiCo₂O₄The precursor of (2) has a sheet structure but no regular structure. NiCo₂O₄See FIG. 9, in which NiCo₂O₄See fig. 9 (a); NiCo₂O₄See fig. 9 (b); as can be seen from FIG. 9(a), NiCo₂O₄A sheet-like structure without a uniform shape; FIG. 9(b) shows NiCo₂O₄X-ray powder diffraction pattern of (A) with NiCo₂O₄(JCPDS No. 20-0781).

The detection picture of the corresponding Ni-Co-S nano material is shown in figure 10, wherein the macroscopic scanning electron microscope picture of the Ni-Co-S nano material is shown in figure 10 (a); the X-ray powder diffraction pattern of Ni-Co-S is shown in FIG. 10 (b); the CV diagram of Ni-Co-S is shown in FIG. 10 (c); the constant current charge-discharge diagram of Ni-Co-S is shown in FIG. 10 (d); the EIS diagram of Ni-Co-S is shown in FIG. 10 (e); as can be seen from FIG. 10(a), Ni-Co-S is a granular structure; FIG. 10(b) is an X-ray powder diffraction pattern of Ni-Co-S with NiCo₂S₄(JCPDS No.20-0782)、Co₉S₈(JCPDS No. 19-0364); as can be seen from FIGS. 10(c) and 10(d), when the Ni-Co-S nanomaterial without carbon spheres as a template is applied to a three-electrode, the specific capacitance of the invented material reaches 1472F/g at a current density of 1A/g; FIG. 10(e) is a graph showing an impedance spectrum of a Ni-Co-S nanomaterial without carbon spheres as a template when applied to a three-electrode structure, wherein a semicircular radius appearing in a high frequency region is observed to be large, indicating that the resistance of the electrode material is slightly large; however, the slope of the straight line in the low frequency region is second only to the Ni-Co-S material in example 1, indicating that the material is second only to the Ni-Co-S electrode material in example 1 when used as an electrode material of a supercapacitor.

Example 4

Ni-Co-S hollow sphere nanomaterials were prepared as in example 1 except that hollow NiCo₂O₄The heating temperature of the reaction and vulcanization with thioacetamide is changed to 120 ℃, and the corresponding Ni-Co-S hollow sphere nano material is obtained.

The corresponding Ni-Co-S nano material is a hollow sphere, and the surface of the nano material is of a rice-grain structure; its X-ray powder diffraction pattern with NiCo₂S₄(JCPDS No.20-0782)、Co₉S₈(JCPDS No. 19-0364).

Example 5

Ni-Co-S hollow sphere nanomaterials were prepared as in example 1 except that hollow NiCo₂O₄The heating temperature of the reaction and vulcanization with thioacetamide is changed to 160 ℃, and the corresponding Ni-Co-S hollow sphere nano material is obtained.

Example 6

Ni-Co-S hollow sphere nanomaterials were prepared as in example 1 except that hollow NiCo₂O₄The heating temperature of the reaction and vulcanization with thioacetamide is changed to 180 ℃, and the corresponding Ni-Co-S hollow sphere nano material is obtained.

The corresponding Ni-Co-S nano material is a hollow sphere with uniform size and a rice-grain-shaped structure on the surface; its X-ray powder diffraction pattern with NiCo₂S₄(JCPDS No.20-0782)、Co₉S₈(JCPDS No. 19-0364).

Example 7

Ni-Co-S hollow sphere nanomaterials were prepared as in example 1 except that hollow NiCo₂O₄The heating temperature of the reaction and vulcanization with thioacetamide is changed to 190 ℃, and the corresponding Ni-Co-S hollow sphere nano material is obtained.

The performances of the Ni-Co-S nano-materials synthesized at different vulcanization temperatures are compared: samples obtained at different vulcanization temperatures are applied to a three-electrode system as electrode materials, the specific capacitance of the vulcanization temperatures of 120 ℃, 160 ℃, 170 ℃, 180 ℃ and 190 ℃ is 1345F/g, 1720F/g, 1940F/g, 1760F/g and 1030F/g respectively under the condition that the current density is 5A/g, and obviously, when the vulcanization temperature is 170 ℃, the prepared sulfide has the best specific capacitance when being used as the electrode material.

Example 8

A vulcanized nanomaterial was prepared according to the method of example 1, except that sodium citrate was not added. The resulting vulcanized nanomaterial was morphologically comparable to the vulcanized nanomaterial of example 1, with the surface of the hollow vulcanized nanomaterial of example 8 being built up from larger nanoparticles than the rice-like buildup of example 1. Experiments prove that when the vulcanized nano material in the embodiment 8 is applied to three electrodes as an electrode material, the specific capacitance of the material reaches 980F/g under the current density of 1A/g.

Example 9

The preparation method of the vulcanized nano material comprises the following steps:

(1) dissolving hexamethylenetetramine and nickel nitrate in water, and heating and reacting for 4 hours at 95 ℃ under the condition of continuous mixing to prepare a nano material precursor; the concentration of the divalent nickel ions is 0.010mol/L, and the molar ratio of the divalent nickel ions to the hexamethylenetetramine is 1: 0.5;

(2) calcining the nano material precursor at 500 ℃ for 1 h;

(3) dispersing the calcined product in anhydrous ethanol containing thioacetamide by ultrasonic dispersion for 5min, wherein the addition amount of the calcined product is 0.2mmol and the addition amount of the thioacetamide is 0.3mmol relative to 20mL of the anhydrous ethanol; then, the reaction was heated at 190 ℃ for 10 hours.

Experiments prove that when the vulcanized nano material in the embodiment 9 is used as an electrode material and applied to three electrodes, the specific capacitance of the material reaches 1300F/g under the current density of 1A/g.

Example 10

(1) dissolving hexamethylenetetramine and nickel nitrate in water, and heating and reacting for 8 hours at 80 ℃ under the condition of continuous mixing to prepare a nano material precursor; the concentration of the divalent nickel ions is 0.002mol/L, and the molar ratio of the divalent nickel ions to the hexamethylenetetramine is 1: 3;

(2) calcining the precursor of the nano material at 300 ℃ for 4 h;

(3) ultrasonically dispersing the calcined product for 60min in absolute ethyl alcohol containing thioacetamide, wherein the addition amount of the calcined product is 0.05mmol and the addition amount of the thioacetamide is 0.15mmol relative to 20mL of absolute ethyl alcohol; then heating and reacting for 14h at 120 ℃.

Experiments prove that when the vulcanized nano material in the embodiment 10 is used as an electrode material and applied to three electrodes, the specific capacitance of the material reaches 890F/g under the current density of 1A/g.

Comparative example 1

A nanomaterial was prepared as in example 1, except that the step of dispersing the calcined product in anhydrous ethanol containing thioacetamide and then heating the reaction was not performed, thereby obtaining NiCo₂O₄And (3) nano materials.

NiCo₂O₄The detection of the hollow spheres is shown in figure 3 of example 1.

NiCo₂O₄The properties of the hollow spheres as electrode material when applied to a three-electrode body are shown in FIG. 11, where NiCo₂O₄CV diagram of hollow sphere is shown in FIG. 11(a), NiCo₂O₄The constant current charge-discharge diagram of the hollow sphere is shown in FIG. 11(b), NiCo₂O₄The EIS diagram of the hollow sphere is shown in FIG. 11(c), and NiCo can be obtained from FIGS. 11(a) and 11(b)₂O₄When the hollow sphere is used as an electrode material and applied to a three-electrode system, the specific capacitance performance is better, and under the current density of 1A/g, the specific capacitance of the material reaches 660F/g and is lower than that of the Ni-Co-S hollow sphere; FIG. 11(c) shows NiCo₂O₄When the hollow sphere is used as an electrode material and applied to a three-electrode impedance spectrogram, the semi-circle radius appearing in a high-frequency region can be observed to be relatively small from a curve, which shows that NiCo₂O₄The hollow sphere electrode material has small resistance; however, the slope of the straight line in the low frequency region is small, which indicates that the performance of the electrode material is inferior to that of the Ni-Co-S hollow sphere material.

Comparative example 2

Adding 20mg of the carbon spheres obtained in the preparation example 2 into a beaker containing 40mL of deionized water and 0.4mmol of cobalt nitrate hexahydrate, carrying out ultrasonic treatment for 10min, adding 0.5mmol of HMTA and 0.05mmol of TSC under stirring, and continuing to stir for 40min to obtain a uniform solution; the above solution was transferred to a 50mL round bottom flask and reacted by oil bath hydrothermal at 90 ℃ for 6h to prepare black powder Co (OH)₂C; the obtained black powder Co (OH)₂The washed and dried material is calcined in a muffle furnace to remove the template, and hollow Co is obtained₃O₄A precursor;

mixing the hollow Co obtained above₃O₄Adding 0.065mmol of the precursor into a solution containing 0.261mmol of TAA and 20mL of absolute ethyl alcohol, and carrying out ultrasonic treatment for 20min to obtain a uniform solution; the solution is transferred into a reaction kettle with a Teflon coating, and sulfide black powder is obtained by the reaction of solvothermal reaction at 170 ℃ for 13h in an oven.

And washing, centrifuging and drying the obtained sulfide black powder to obtain the Co-S hollow sphere.

Co₃O₄The detection pattern of the hollow sphere is shown in FIG. 12, wherein Co₃O₄A macroscopic scanning electron micrograph of the hollow sphere is shown in fig. 12 (a); co₃O₄The X-ray powder diffraction pattern of the hollow sphere is shown in FIG. 12 (b); as can be seen from FIG. 12(a), Co₃O₄Hollow spheres with a sheet structure and uniform size, about 900 nm; FIG. 9(b) shows Co₃O₄X-ray powder diffraction pattern of hollow sphere, and Co₃O₄(JCPDS No. 43-1003).

The detection picture of the Co-S hollow sphere is shown in FIG. 13, wherein the macroscopic scanning electron microscope picture of the Co-S hollow sphere is shown in FIG. 13 (a); the X-ray powder diffraction pattern of the Co-S hollow spheres is shown in FIG. 13 (b); CV diagram of Co-S hollow sphere is shown in FIG. 13 (c); the constant current charge-discharge diagram of the Co-S hollow sphere is shown in FIG. 13 (d); the EIS diagram of the Co-S hollow sphere is shown in FIG. 13 (e).

As can be seen from FIG. 13(a), the Co-S hollow spheres are rice-grain-shaped hollow spheres with uniform size, and the diameter of the Co-S hollow spheres is about 900 nm; FIG. 13(b) is an X-ray powder diffraction pattern of Co-S hollow spheres, and Co₄S₃(JCPDS No.02-1458)、Co₉S₈(JCPDS No. 02-1459); as can be seen from fig. 13(c) and 13(d), when the Co-S hollow sphere is applied to three electrodes as an electrode material, the specific capacitance of the invented material reaches 578F/g at a current density of 1A/g; fig. 13(e) shows an impedance spectrum of a Co-S hollow sphere as an electrode material applied to a three-electrode, and it can be observed from the curve that the semi-circle radius appearing in the high frequency region is only second to that of a Ni-Co-S hollow sphere material without a carbon sphere as a template, which indicates that the resistance of the electrode material is relatively small; however, the linear inclination in the low frequency region is only larger than that of NiCo₂O₄The material is large, which shows that the material is relatively poor when used as a super capacitor electrode material, but is better than NiCo₂O₄An electrode material.

In conclusion, when the vulcanized nano material is applied to three electrodes, the specific capacitance is as high as 2210F/g, the lowest specific capacitance can reach about 900F/g under the current density of 1A/g, and the linear gradient in a low-frequency region is larger, so that the vulcanized nano material is an excellent super capacitor electrode material.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims

1. A preparation method of a vulcanized nano material is characterized by comprising the following steps:

(1) dissolving hexamethylenetetramine and a divalent nickel source in water, and heating and reacting under a continuous mixing condition to prepare a nano material precursor;

(2) calcining the nano material precursor;

(3) dispersing the calcined product in anhydrous ethanol containing thioacetamide, and then heating for reaction;

in the step (3), the addition amount of the calcined product is 0.05-0.2mmol and the addition amount of thioacetamide is 0.15-0.3mmol relative to 20mL of absolute ethanol;

a divalent cobalt source, carbon spheres and citrate are also added into the water in the step (1);

the heating reaction conditions in the step (3) comprise: the temperature is 120-180 ℃;

wherein the molar ratio of the divalent nickel source to the divalent cobalt source to the hexamethylenetetramine to the citrate is 1: 1-2: 0.75-2.5: 0.125-0.25;

wherein, the heating reaction conditions in the step (1) comprise: the temperature is 80-95 ℃ and the time is 4-8 h;

the calcining conditions in the step (2) include: the temperature is 300-500 ℃, and the time is 1-4 h.

2. The production method according to claim 1, wherein the concentration of divalent nickel ions in the solution is 0.002 to 0.010 mol/L; and/or the molar ratio of the divalent nickel ions to the hexamethylenetetramine is 1: 0.5-3.

3. The production method according to claim 1 or 2, wherein the manner of dispersion in step (3) is ultrasonic dispersion;

and/or the heating reaction conditions in the step (3) comprise: the time is 10-14 h.

4. The method according to claim 3, wherein the time for ultrasonic dispersion is 5 to 60 min.

5. The method of claim 2, wherein the carbon spheres are prepared by a chemical vapor deposition method, a templating method, a carbon source cracking method, or a hydrothermal method.

6. The method of claim 5, wherein the carbon spheres are produced by a hydrothermal method.

7. The method of claim 6, wherein the hydrothermal process is carried out by: dissolving cetyl trimethyl ammonium bromide and glucose into water, and then reacting at 160-180 ℃ for 10-14h to obtain a brown product; wherein, relative to 20mL of water, the dosage of the hexadecyl trimethyl ammonium bromide is 0.04-0.08g, and the dosage of the glucose is 1.5-2.5 g.

8. The preparation method according to claim 7, wherein the hydrothermal method further comprises washing the brown product with deionized water and/or absolute ethyl alcohol for 2-6 times, and drying in an oven at 50-70 ℃ to obtain the nano carbon sphere powder.

9. The production method according to claim 1 or 2, wherein the divalent nickel source is NiSO₄、Ni(NO₃)₂、NiCl₂、NiBr₂And NiAc₂One or more of (a).

10. The production method according to claim 1 or 2, wherein the divalent cobalt source is CoSO₄、Co(NO₃)₂、CoCl₂、CoBr₂And CoAc₂One or more of;

and/or the citrate is sodium citrate and/or potassium citrate.

11. The vulcanized nanomaterial prepared by the preparation method according to any one of claims 1 to 10, the vulcanized nanomaterial having a hollow sphere structure.

12. Use of the sulfidised nanomaterial of claim 11 as an electrode material.