CN113223871B

CN113223871B - Preparation and application of NiO/C composite electrode material with foam nickel sheet as substrate

Info

Publication number: CN113223871B
Application number: CN202110407041.2A
Authority: CN
Inventors: 陈伟; 付民; 张志豪
Original assignee: Shandong University of Science and Technology
Current assignee: Shandong University of Science and Technology
Priority date: 2021-04-15
Filing date: 2021-04-15
Publication date: 2023-06-16
Anticipated expiration: 2041-04-15
Also published as: CN113223871A

Abstract

The invention belongs to the field of energy storage materials, and particularly relates to preparation and application of a NiO/C composite electrode material with a foam nickel sheet as a substrate. The NiO/C composite material is prepared on the foam nickel sheet, and is loaded on the foam nickel sheet in situ by a method of oxidizing and coating and carbonizing, compared with the granular transition metal oxide coated active material, the NiO/C composite material on the foam nickel sheet prepared by the method has the advantages that the combination of NiO and C on the foam nickel sheet is tighter, and the NiO/C composite material taking the foam nickel sheet as a substrate can be directly used as an electrode material without additional coating operation.

Description

Preparation and application of NiO/C composite electrode material with foam nickel sheet as substrate

Technical Field

The invention belongs to the field of energy storage materials, and particularly relates to preparation and application of a NiO/C composite electrode material with a foam nickel sheet as a substrate.

Background

The disclosure of this background section is only intended to increase the understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art already known to those of ordinary skill in the art.

The energy consumption is increasing, with consequent massive consumption of fossil fuels, climate change and environmental destruction. In order to solve this series of problems, development of efficient, clean and sustainable novel energy sources is urgent, and related energy conversion and storage technologies are also one of the important points of attention. Super capacitor is used as a novel energy storage device which is different from traditional capacitor and battery, and has the advantages of high power, long service life period, extremely fast charge and discharge speed and the like, which brings attention to the mass of scientific researchers, and is one of the most important energy storage devices at present. Although supercapacitors can exhibit higher capacitive performance, their low energy density is a major disadvantage. Therefore, there is an urgent need to produce supercapacitors with high energy and power densities.

Although transition metals (e.g., mn, fe, co, ni, etc.) have been widely used in various energy storage device fields due to their layered structure and various oxidation states of oxides. However, the transition metal oxide has problems of poor cycle stability and poor conductivity mainly in the case of using it as an electrode material.

The inventors have studied and found that some prior arts improve the disadvantages of the transition metal oxide as an electrode material by coating the active material on the surface of the transition metal oxide, but the prior arts are limited to the surface coating of nano-sized particles, and the modified particles need to be coated on other electrode sheets for use in use, so that the risk of peeling exists. In addition, some of the prior art prepares an active material-coated transition metal oxide by calcination using a precursor, but its size is still nano-sized particles, so that there are problems of flaking, poor cycle performance when coated on an electrode sheet.

Disclosure of Invention

In order to solve the problems of peeling and poor cycle performance of active substances coated on the surfaces of transition metal oxide nano-scale particles in the prior art, the invention provides preparation and application of a NiO/C composite electrode material taking a foam nickel sheet as a substrate.

Specifically, the invention is realized by the following technical scheme:

in a first aspect, the present invention provides a method for preparing a NiO/C composite material using a foam nickel sheet as a substrate, including: calcining the foam nickel sheet, coating Polydopamine (PDA), and carbonizing.

In a second aspect of the present invention, a NiO/C composite material with a foamed nickel sheet as a substrate is provided, which is prepared by a method for preparing a NiO/C composite material with a foamed nickel sheet as a substrate.

In a third aspect of the invention, an application of a NiO/C composite material with a foam nickel sheet as a substrate in preparing an electrode material is provided.

One or more embodiments of the invention have the following beneficial effects:

1) In the prior art, the active material is coated on the surface of the granular transition metal oxide, the combination effect of the active material and the transition metal oxide is poor, and the NiO and the active material are combined more tightly under the supporting action of the foam nickel sheet by selecting proper calcination, carbonization temperature and time. And the NiO/C composite material with the foam nickel sheet as a substrate can be directly used as an electrode material without additional coating operation. The carbon material after the carbonization of the polymer is organically combined with the transition metal oxide with the pseudo capacitance, so that the defect of poor capacitance performance of a single carbon material or transition metal oxide is overcome.

2) According to the invention, as NiO is generated in situ on the foam nickel sheet, the surface of NiO is coated with the active material, for NiO, under the supporting of the foam nickel sheet and the coating action of the active material, the stress on the upper surface and the lower surface is balanced, the NiO and the active material are distributed in a plane, the two phases are combined more tightly, and the problems of uneven stress and poor combination effect of the single-particle surface coated active material are solved.

3) The NiO/C composite electrode material with the foam nickel as the substrate is prepared by adopting a high-temperature oxidation and high-temperature carbonization method, the operation is simple and easy, any conductive additive and adhesive are not needed, the utilization rate of the electrode material is improved, the impedance of the obtained electrode is reduced, and a road is indicated for the current combined application of the electrode material and the polymer material.

4) Compared with a single NiO material, the NiO/C composite material prepared by the invention with the foam nickel as a substrate can expose more active sites, reduce the diffusion path of ions, effectively relieve the influence caused by volume expansion and effectively improve the electrochemical performance of the electrode.

5) The morphology of the NiO/C composite electrode material prepared by the invention and taking the foam nickel as the substrate is characterized by adopting a scanning electron microscope, and the electrochemical performance of the NiO/C composite electrode material is evaluated by adopting a cyclic voltammetry and electrochemical impedance method, so that the NiO/C composite electrode material prepared by the invention and taking the foam nickel as the substrate has excellent electrochemical performance, and has good application prospect in the field of energy storage devices.

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 invention. Embodiments of the present invention are described in detail below with reference to the attached drawing figures, wherein:

FIG. 1 is a scanning electron microscope photograph of a layer of NiO material on the surface of a foam nickel obtained in example 1 of the present invention through high temperature oxidation;

FIG. 2 is a scanning electron microscope photograph of NiO@PDA composite material obtained in example 1 of the present invention;

FIG. 3 is a scanning electron microscope photograph of the NiO/C composite material obtained in example 1 of the present invention;

FIG. 4 shows the XRD pattern of the NiO material obtained in example 1 of the present invention;

FIG. 5 is a cyclic voltammogram of the NiO/C composite obtained in example 1 of the present invention at different scan rates;

FIG. 6 is an electrochemical impedance curve of the NiO/C composite material obtained in example 1 of the present invention.

Detailed Description

The invention will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention. The experimental procedures, which do not address the specific conditions in the examples below, are generally carried out under conventional conditions or under conditions recommended by the manufacturer.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments in accordance with the present disclosure. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.

Specifically, the invention is realized by the following technical scheme:

in a first aspect, the present invention provides a method for preparing a NiO/C composite material using a foam nickel sheet as a substrate, including: calcining the foam nickel sheet, coating the PDA, and carbonizing to obtain the final product.

According to the invention, as NiO is generated in situ on the foam nickel sheet, the NiO surface coats the active material, for NiO, under the supporting of the foam nickel sheet and the coating action of the active material, the stress on the upper surface and the lower surface is balanced, the NiO and the active material are distributed in a plane, the two phases are combined more tightly, and the problems of uneven stress and poor combination effect of the single particle surface coated active material are solved.

In one or more embodiments of the invention, the calcination temperature is 550-900 ℃ and the calcination time is 0.5-3 hours, preferably 650 ℃,2 hours. In the process, a layer of uniform NiO can be generated on the foam nickel by high-temperature calcination in an air atmosphere without adding any reagent.

Through calcination, cladding and carbonization steps under specific conditions, the NiO/C composite material maintains a three-dimensional macroporous structure of foam nickel, and the structure provides a smooth electron channel for rapid charge/discharge reaction and can reduce the impedance of electrolyte ions during diffusion. In addition, niO and PDA directly grow on the surface of the foam nickel in the synthesis process, no binder is needed, the contact area between the active substance and the electrolyte is increased, and meanwhile, the charge transmission and the ion transmission are accelerated.

In the calcination process, the temperature rising rate is 3-8 ℃/min, preferably 5 ℃/min.

The calcination is performed under an inert gas atmosphere, preferably, an inert gas atmosphere selected from nitrogen, helium and argon.

In one or more embodiments of the invention, the step of wrapping the PDA comprises: and (3) soaking the calcined foam nickel sheet in a dopamine hydrochloride solution, introducing air to perform self-polymerization reaction, and drying.

In one or more embodiments of the invention, the dopamine hydrochloride solution has a pH of 7-12, preferably 8.5.

In one or more embodiments of the present invention, the preparation method of the dopamine hydrochloride solution includes taking a proper amount of dopamine, and adding a buffer solution with a pH value of 7-12.

The self-polymerization time is 24 to 72 hours, preferably 48 hours.

In one or more embodiments of the invention, the buffer solution is selected from a tris solution.

In one or more embodiments of the invention, the carbonization temperature is 600-900 ℃, and the carbonization time is 1-3 hours, preferably 700 ℃,2 hours.

NiO is a typical pseudocapacitive material, and the surface can rapidly undergo reversible redox reactions. After PDA carbonization, a layer of filar is generated on the NiO surface, which exposes more active sites, and is also more favorable for rapid absorption and release of electrolyte ions in the charge storage process, so that the electrode has good multiplying power performance. Therefore, the NiO/C composite material synthesized by the method combines the pseudocapacitance of NiO and the double capacitance of the carbon material, and can effectively improve the electrochemical property of the composite material.

In one or more embodiments of the invention, the carbonization temperature is higher than the calcination temperature;

preferably, the carbonization temperature is 50-250 ℃, more preferably 50 ℃, above the calcination temperature.

When NiO is generated on the foam nickel sheet by oxidation, due to the intervention of oxygen atoms, internal stress concentration phenomenon can exist between the NiO and the matrix, the carbonization temperature is higher than the calcination temperature so as to release a part of internal stress, the stripping of the NiO and the matrix is avoided, meanwhile, in the stress release process, the PDA grows on the surface of the NiO in situ, so that the stress conditions of the upper surface and the lower surface of the NiO are basically consistent, the stability of the structure of the foam nickel sheet, the NiO and the PDA is maintained, and the electrochemical performance of the material is further improved.

In the carbonization process, the heating rate is 1-5 ℃/min, preferably 2 ℃/min.

Compared with the prior art, the invention has the advantages that: the foam nickel with the three-dimensional macroporous structure provides an ideal matrix for loading NiO and PDA, and the carbon material with the double-layer capacitor and the transition metal oxide with the pseudo-capacitor are organically combined, so that the electrochemical performance of the single-component material is improved. Meanwhile, a compact NiO layer is formed on the foam nickel substrate by a high-temperature oxidation method without any conductive additive or adhesive, a carbon-rich biological material PDA is used as a precursor, and the carbonization temperature is controlled to obtain the carbon material with rich pore structures. The main advantages of the material are simple reaction, no pollution, and good electrochemical performance. The method not only increases the specific surface area of the composite material, but also can enable the electron transfer under the condition of high current density to be quicker, so that the NiO/C composite electrode material taking the foam nickel as the substrate has good electrochemical performance.

The invention will now be described in further detail with reference to the following specific examples, which should be construed as illustrative rather than limiting.

Example 1

Using untreated foam nickel flakes; setting the heating rate in a muffle furnace to be 5 ℃/min, preserving heat for 2 hours at 650 ℃, and naturally cooling to room temperature. 0.01g of dopamine hydrochloride is weighed, dissolved in 20ml of tris (hydroxymethyl) aminomethane solution with pH=8.5, put into the treated foam nickel sheet, soaked for 48 hours, taken out and put into a vacuum oven for drying. And (3) putting the dried product in the previous step into a tube furnace in a nitrogen atmosphere, heating at a heating rate of 2 ℃/min, preserving heat for 2 hours at 700 ℃, and naturally cooling to room temperature to obtain a final sample.

And (3) taking the final sample processed in the previous step as a working electrode, taking a calomel electrode as a reference electrode, taking a platinum sheet electrode as a counter electrode, and taking a KOH solution of 3mol/L as an electrolyte to assemble a three-electrode system for electrochemical test.

Fig. 1 is a scanning electron microscope photograph of the obtained foam nickel sheet oxidized to NiO material at high temperature, and it is obvious that NiO is present on the surface.

Fig. 2 is a scanning electron microscope photograph of the resulting nio@pda composite material, and it can be seen that the PDA was uniformly supported on the foam nickel matrix.

FIG. 3 is a scanning electron micrograph of the resulting NiO/C composite, showing a layer of floc grown on the foam nickel substrate.

FIG. 4 shows XRD patterns of the resulting NiO, in which three distinct diffraction peaks are assigned to the (111), (200) and (220) crystal planes (JCPDS No. 04-0850) of Ni at 44.5, 51.8, 76.3℃respectively, and five distinct diffraction peaks are assigned to the (101), (012), (110), (113) and (202) crystal planes (JCPDS No. 44-1159) of NiO at 37.2, 43.2, 62.8, 75.4, 79.3℃respectively, and it can be inferred that the target material was successfully synthesized by this method.

Fig. 5 is a cyclic voltammogram of a working electrode tested in a three cell system. According to a calculation formula of the specific capacitance, the specific capacitance of the electrode at a scanning rate of 2mV/s is about 404F/g, and when the scanning rate is up to 100mV/s, the specific capacitance is about 236F/g, which shows that the assembled super capacitor has good capacitance and rate capability.

Fig. 6 is an electrochemical impedance diagram of the assembled NiO/C composite as electrode material tested in a three-cell system, which shows that the impedance diagram has a smaller slope, i.e., a smaller electrolyte ion transport resistance, which is beneficial for charge transport.

Example 2

The same as in example 1, except that the muffle furnace calcination temperature was 550 ℃.

Example 3

The same as in example 1, except that the muffle furnace calcination temperature was 750 ℃.

Example 4

The same as in example 1, except that the muffle furnace calcination temperature was 850 ℃.

Example 5

The same as in example 1, except that the tube furnace carbonization temperature was 600 ℃.

Example 6

The same as in example 1, the difference was only that the tube furnace carbonization temperature was 800 ℃.

Example 7

The same as in example 1, except that the tube furnace carbonization temperature was 900 ℃.

Example 8

The same as in example 1, except that the dopamine was polymerized for 72 hours.

Example 9

The same as in example 1, except that the dopamine polymerization time was 24h.

Table 1 shows that the electrochemical properties of the materials obtained in examples 1 to 9 are compared, and that the specific capacitance is high when the carbonization temperature is higher than the calcination temperature in comparative examples 5, 6 and 7. As is clear from comparative examples 1, 3 and 4, the specific capacitance is low when the calcination temperature is higher than the carbonization temperature. As is clear from comparative examples 1, 2, 6 and 7, the specific capacitance is high when the carbonization temperature is 50℃higher than the calcination temperature.

TABLE 1 comparison of electrochemical Properties of the materials obtained in examples 1 to 9

	Specific capacitance of 2mV/s (F/g)	Specific capacitance of 100mV/s (F/g)
			Example 1	404	236
Example 2	390	230
			Example 3	399	232
Example 4	388	229
			Example 5	387	224
Example 6	391	226
			Example 7	392	228
Example 8	386	221
			Example 9	386	220

The foregoing description is only a preferred embodiment of the present invention, and the present invention is not limited thereto, but it is to be understood that modifications and equivalents of some of the technical features described in the foregoing embodiments may be made by those skilled in the art, although the present invention has been described in detail with reference to the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The preparation method of the NiO/C composite material taking the foam nickel sheet as the substrate is characterized by comprising the following steps of: calcining the untreated foam nickel sheet, coating the foam nickel sheet with PDA, and carbonizing to obtain the final product;

the calcination process is carried out in an air atmosphere, the calcination temperature is 550-900 ℃, the calcination time is 0.5-3h, and the temperature rising rate is 3-8 ℃/min; generating a layer of NiO on the foam nickel;

the step of wrapping the PDA includes: soaking the calcined foam nickel sheet in dopamine hydrochloride solution, introducing air to perform self-polymerization reaction, and drying;

placing the dried product in the previous step into a tube furnace in a nitrogen atmosphere, heating, preserving heat, and naturally cooling to room temperature to obtain a final sample;

the carbonization temperature is 600-900 ℃, the carbonization time is 1-3h, and the heating rate is 1-5 ℃/min;

the carbonization temperature is 50-250 ℃ higher than the calcination temperature;

after PDA carbonization, a layer of filiform substances is generated on the surface of NiO;

the prepared NiO/C composite material taking the foam nickel sheet as the substrate is used for assembling the super capacitor.

2. The method for preparing the NiO/C composite material with the foam nickel sheet as a substrate according to claim 1, wherein the calcination temperature is 650 ℃, and the calcination time is 2 hours;

in the calcination process, the temperature rising rate is 5 ℃/min.

3. The method for preparing the NiO/C composite material with the foam nickel sheet as a substrate according to claim 1, wherein the pH value of the dopamine hydrochloride solution is 7-12.

4. The method for preparing a NiO/C composite material based on a foam nickel sheet according to claim 3, wherein the pH value of the dopamine hydrochloride solution is 8.5.

5. The method for preparing the NiO/C composite material with the foam nickel sheet as a substrate according to claim 1, wherein the method for preparing the dopamine hydrochloride solution comprises the steps of taking a proper amount of dopamine, and adding a buffer solution with a pH value of 7-12.

6. The method for preparing a nickel foam sheet-based NiO/C composite according to claim 5, wherein the buffer solution is selected from the group consisting of tris (hydroxymethyl) aminomethane solutions.

7. The method for preparing the NiO/C composite material based on the foam nickel sheet according to claim 1, wherein the carbonization temperature is 700 ℃ and the carbonization time is 2h.

8. The method for preparing a NiO/C composite material based on a foamed nickel sheet according to claim 1, wherein the carbonization temperature is 50 ℃ higher than the calcination temperature;

in the carbonization process, the heating rate is 2 ℃/min.

9. The NiO/C composite material with foamed nickel sheet as a substrate prepared by the preparation method of the NiO/C composite material with foamed nickel sheet as a substrate according to any one of claims 1 to 8.