Preparation method, product and application of a 3D hydrangea-shaped electrode material

Abstract

The present invention relates to the technical field of new energy material preparation, and particularly to a preparation method, product and application of a 3D hydrangea-shaped electrode material. The preparation method includes the following steps: dissolving a Co salt, an Al salt, urea and cetyltrimethylammonium bromide in water to obtain a mixed solution A; impregnating a substrate in the mixed solution A for hydrothermal reaction to obtain a substrate with a precursor grown thereon; dissolving a Ce salt and an organic ligand in an organic solvent to obtain a mixed solution B; impregnating the substrate with the precursor grown thereon in the mixed solution B for hydrothermal reaction to obtain the 3D hydrangea-shaped electrode material. The present invention synthesizes a unique 3D hydrangea-shaped electrode material through a simple hydrothermal reaction. Due to the synergistic effect of layered double hydroxides and metal-organic frameworks, the electrode material has a high specific capacitance and high cycle stability.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy material preparation, and particularly to a preparation method, product and application of a 3D hydrangea-shaped electrode material. Background Art

[0002] With the increasing attention of people to environmental protection, the research on renewable energy and sustainable energy storage systems has gradually become a hot topic in the scientific community. Long-term economic energy storage for fixed applications is an important missing factor for realizing a future society dominated by renewable energy. Among many energy storage devices, such as supercapacitors, batteries, fuel cells and electrochromic devices, supercapacitors have received more and more attention due to their high capacitance, good stability, fast charge and discharge process and low maintenance cost. However, their narrow voltage range and low energy density seriously restrict their wider applications. The charge storage ability of supercapacitors mainly depends on the electrode material. Therefore, it is crucial to develop high-performance electrode materials with high specific capacitance and high cycle stability. The progress of electrode materials can not only improve the overall performance of supercapacitors, but also promote their applications in fields such as renewable energy and power storage. Therefore, the research and innovation of electrode materials is an important direction to improve the technical level of supercapacitors. Summary of the Invention

[0003] Based on the above, the present invention provides a preparation method, product and application of a 3D hydrangea-shaped electrode material.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] One of the technical solutions of the present invention is a preparation method of a 3D hydrangea-shaped electrode material, comprising the following steps:

[0006] Dissolve Co salt, Al salt, urea and cetyltrimethylammonium bromide (CTAB) in water to obtain a mixed solution A;

[0007] Immerse the substrate in the mixed solution A for hydrothermal reaction to obtain a substrate with a precursor grown thereon;

[0008] Dissolve Ce salt and an organic ligand in an organic solvent to obtain a mixed solution B;

[0009] Immerse the substrate with the precursor grown thereon in the mixed solution B for hydrothermal reaction to obtain the 3D hydrangea-shaped electrode material (CoAl-LDH@Ce-MOF).

[0010] Another technical solution of the present invention is a 3D hydrangea-shaped electrode material prepared according to the above preparation method.

[0011] The third technical solution of the present invention is the application of the above-mentioned 3D hydrangea-shaped electrode material in a supercapacitor.

[0012] The fourth technical solution of the present invention is a supercapacitor, the electrode material of which includes the above-mentioned 3D hydrangea-shaped electrode material.

[0013] The present invention discloses the following technical effects:

[0014] (1) Compared with the existing complex processes, the present invention uses Co salt (cobalt nitrate hexahydrate), Al salt (aluminum nitrate nonahydrate), Ce salt and organic ligand (p-aminobenzoic acid) as raw materials to synthesize a unique 3D hydrangea-shaped electrode material CoAl-LDH@Ce-MOF through a simple hydrothermal reaction. Due to the unique 3D hydrangea structure, the specific surface area of the electrode material after the combination of CoAl-LDH and Ce-MOF increases, providing more reactive sites, which can significantly reduce its ion transport resistance to improve the capacity performance; in addition, due to the synergistic effect of layered double hydroxide (CoAl-LDH) and metal-organic framework (Ce-MOF), the charge transfer path is effectively shortened, so that the electrode material has high specific capacitance and high cycle stability, providing new ideas for the design and performance optimization of supercapacitor electrode materials.

[0015] (2) In the preparation method of the present invention, the combination of MOFs and LDHs plays an important role in the preparation of advanced electrode materials, which helps to realize high-performance supercapacitors. The electrode material has a relatively high specific surface area and good cycle stability, which is crucial for realizing high-density electrochemical capacitance energy storage. The high specific surface area can provide more active sites, thus enhancing the charge storage capacity; while the excellent cycle stability ensures the stability of electrical performance during long-term use, improving the overall efficiency and lifespan of the supercapacitor. The capacitance retention rate of the 3D hydrangea-shaped electrode material prepared by the present invention reaches 88.5% after 5000 cycles. These characteristics make the electrode material have broad prospects in electrochemical energy storage applications. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1Figures (a)-(d) are SEM images of CoAl-LDH and CoAl-LDH@Ce-MOF electrode materials respectively; among them, (a)-(b) are CoAl-LDH at different magnifications, and (c)-(d) are CoAl-LDH@Ce-MOF at different magnifications.

[0018] Figure 2 The cyclic voltammograms of the CoAl-LDH@Ce-MOF electrode material prepared in Example 1 at 5-100 mV·s -1 under different scanning rates.

[0019] Figure 3 The specific capacitance change of the CoAl-LDH@Ce-MOF electrode material prepared in Example 1 at 1-10 A·g -1 current density.

[0020] Figure 4 The cycling performance graph of the CoAl-LDH@Ce-MOF electrode material prepared in Example 1 at 10 A·g -1 current density for 5000 cycles.

[0021] Figure 5 The BET comparison graph of the CoAl-LDH and CoAl-LDH@Ce-MOF electrode materials prepared in Example 1; among them, (a) is CoAl-LDH and (b) is CoAl-LDH@Ce-MOF. Detailed implementation manners

[0022] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0023] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0024] Unless otherwise noted, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0025] Without departing from the scope or spirit of the present invention, various modifications and variations to the specific embodiments of the description of the present invention will be apparent to those skilled in the art. Other embodiments obtained from the description of the present invention will be apparent to those skilled in the art. The description of the present invention and the examples are merely exemplary.

[0026] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0027] By adjusting the structure to achieve the optimal synergy between metal-organic framework materials (MOFs) and layered double hydroxides (LDHs), the advantages of both can be maximized. MOFs can serve as the active sites of electrode materials, while LDHs can act as co-catalysts. Due to the surface property differences between the two, the combination can enhance the dispersibility of the materials and reduce particle aggregation. In addition, LDHs have excellent mechanical properties, which can improve the stability and durability of the composite materials. The combination of MOFs and LDHs is expected to create electrode materials with excellent performance, which are widely used in fields such as renewable energy and electrochemical energy storage, promoting the development of related technologies.

[0028] The present invention provides a preparation method of a high-performance supercapacitor composite electrode material combining MOFs and LDHs, which solves the technical problems of low conductivity and poor stability of single MOFs or LDHs, and hinders their applicability as pseudocapacitor materials after long-term charge and discharge at high current densities. Aiming at the problems of harsh conditions, inconvenient operation and high energy consumption existing in the existing synthesis technology in the preparation process, the present invention proposes to use nickel foam as a substrate through a simple hydrothermal synthesis method, and load CoAl-LDH on it. In order to further improve the electrochemical performance of the electrode material, Ce-MOF is further compounded on the basis of CoAl-LDH to form a composite electrode material CoAl-LDH@Ce-MOF. It not only has a simple, environmentally friendly and low-cost process flow, but also enables the prepared material to have a high specific capacitance, excellent long-term stability and a low overpotential. In addition, its structure and morphology are controllable. The composite electrode material has a unique 3D hydrangea-like structure. This unique structure increases the specific surface area of the electrode material, provides more reactive sites, improves the electrochemical performance, and at the same time shortens the charge transfer path and promotes the efficiency of electron transfer due to the synergistic effect of layered double hydroxides and metal-organic frameworks, resulting in excellent electrochemical performance of the electrode material.

[0029] The first aspect of the present invention provides a preparation method of a 3D hydrangea-like electrode material, comprising the following steps:

[0030] Dissolve Co salt, Al salt, urea and cetyltrimethylammonium bromide (CTAB) in water to obtain a mixed solution A;

[0031] Immerse the substrate in the mixed solution A for hydrothermal reaction to obtain a substrate with a precursor grown on it;

[0032] Dissolve Ce salt and organic ligand in an organic solvent to obtain a mixed solution B;

[0033] Immerse the substrate with the precursor grown on it in the mixed solution B for hydrothermal reaction to obtain the 3D hydrangea-like electrode material (CoAl-LDH@Ce-MOF).

[0034] In a preferred embodiment of the present invention, the substrate is nickel foam.

[0035] In a preferred embodiment of the present invention, the mass concentration of urea in the mixed solution A is 0.05% - 1%; the mass concentration of cetyltrimethylammonium bromide in the mixed solution A is 0.01% - 0.02%; when the concentration of cetyltrimethylammonium bromide exceeds this range, a 3D hydrangea-like morphology cannot be obtained. The concentration of Al salt in the mixed solution A is 0.03 mol / L; the molar ratio of Co salt to Al salt is 3:1.

[0036] In the present invention, cetyltrimethylammonium bromide plays a role in regulating the morphology of the prepared electrode material.

[0037] In a preferred embodiment of the present invention, the Co salt is Co(NO 3 ) 2 ·6H 2 O; the Al salt is Al(NO 3 ) 3 ·9H 2 O.

[0038] In a preferred embodiment of the present invention, when preparing the substrate with the precursor grown thereon, the temperature of the hydrothermal reaction is 90 - 110 °C, and the time is 6 - 7 hours.

[0039] In a preferred embodiment of the present invention, the molar ratio of the Ce salt to the organic ligand is (0.2 - 0.25):1;

[0040] the Ce salt is Ce(NO 3 ) 3 ·6H 2 O; the organic ligand is p-aminobenzoic acid; the organic solvent is N,N-dimethylformamide.

[0041] The mass concentration of the Ce salt in the mixed solution B is 19 - 20 mg / mL.

[0042] In a preferred embodiment of the present invention, when preparing the 3D hydrangea-like electrode material, the temperature of the hydrothermal reaction is 100 - 120 °C, and the time is 8 - 10 hours.

[0043] In a preferred embodiment of the present invention, the molar ratio of the Co salt to the organic ligand is (0.28 - 0.32):1.

[0044] The second aspect of the present invention provides a 3D hydrangea-like electrode material prepared by the above preparation method.

[0045] The third aspect of the present invention provides the application of the above 3D hydrangea-like electrode material in a supercapacitor.

[0046] The fourth aspect of the present invention provides a supercapacitor, the electrode material of which comprises the above 3D hydrangea-like electrode material.

[0047] The present invention synthesizes 3D nanoflower microsphere structure CoAl-LDH on a substrate (nickel foam) through a hydrothermal synthesis method, in-situ grows Ce-MOF on the basis of the 3D nanoflower microsphere structure CoAl-LDH, and finally synthesizes a 3D hydrangea-like structure composite electrode material CoAl-LDH@Ce-MOF, which increases the active sites of the reaction, enables the electrode material to fully contact the electrolyte solution and is more conducive to the occurrence of electrochemical reactions. In addition, the synergistic effect of CoAl-LDH and Ce-MOF is beneficial to the transport and diffusion of charges on the electrode surface and the fast ion effect, improving the transport of the electrode capacitance. The prepared CoAl-LDH@Ce-MOF electrode material can provide a specific capacitance as high as 3513.3 F·g -1 at 1 A·g -1 , and the capacitance retention rate can still reach 88.5% after 5000 cycle tests, which is a potential high-performance electrode material.

[0048] The technical solutions described in the present invention are all conventional solutions in the art unless otherwise specified. The reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0049] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0050] Example 1

[0051] (1) First, cut the nickel foam into nickel foam flakes of appropriate size, clean them, and dry them for later use; specifically, cut the nickel foam into flakes with a specification of 1 cm × 1 cm × 0.07 cm, then ultrasonically clean with acetone for 10 min, ultrasonically clean with 3M hydrochloric acid twice, 10 min each time; then ultrasonically clean with deionized water three times, 10 min each time; finally, ultrasonically clean with absolute ethanol twice, 10 - 30 min each time; then place the cleaned nickel foam flakes in a vacuum drying oven, dry them at 80 °C for 24 h, and then weigh the nickel foam flakes.

[0052] (2) Dissolve cobalt nitrate hexahydrate Co(NO 3 ) 2 ·6H 2 O and aluminum nitrate nonahydrate Al(NO 3 ) 3 ·9H 2 O in a molar ratio of 3:1, as well as urea and CTAB, in deionized water and stir magnetically to make the solution mix evenly, obtaining a transparent magenta mixed solution; in the mixed solution, Al(NO 3 ) 3 ·9H 2The concentration of O is 0.03 mol / L, the concentration of urea is 1%, and the concentration of CTAB is 0.01%.

[0053] (3) Transfer the prepared mixed solution to a polytetrafluoroethylene high-pressure reaction kettle, then place the dried and cut foam nickel sheet in the high-pressure reaction kettle and seal it; react under hydrothermal conditions at 110 °C for 6 hours, and then cool to room temperature.

[0054] (4) Take out the foam nickel sheet with the pink precursor grown in the high-pressure reaction kettle, wash it, and then dry it; specifically, take out the foam nickel sheet with the pink precursor grown in the high-pressure reaction kettle in step (3), and then wash it successively with deionized water and absolute ethanol, and finally dry the washed foam nickel sheet in a vacuum drying oven at a constant temperature of 60 °C.

[0055] (5) Pour Ce(NO 3 ) 3 ·6H 2 O (0.3871 g) and p-aminobenzoic acid (0.5451 g) into 20 ml of N,N-dimethylformamide (DMF), stir for 1 h, and then ultrasonically disperse for 30 min to obtain a light yellow solution.

[0056] (6) Transfer the prepared light yellow solution to a polytetrafluoroethylene high-pressure reaction kettle, then place the CoAl-LDH foam nickel sheet with the pink precursor grown in the high-pressure reaction kettle and seal it, and react hydrothermally at 100 °C for 8 hours, and cool to room temperature to obtain the CoAl-LDH@Ce-MOF electrode material.

[0057] Figure 1 In (a)~(d) are the SEM images of the CoAl-LDH and CoAl-LDH@Ce-MOF electrode materials respectively; among them, (a)~(b) are CoAl-LDH at different magnifications, and (c)~(d) are CoAl-LDH@Ce-MOF at different magnifications. From Figure 1 It can be seen that the CoAl-LDH@Ce-MOF electrode material has more chemical active sites, which can accelerate the electrochemical reaction and thus provide a larger capacitance.

[0058] Verify the performance of the CoAl-LDH@Ce-MOF electrode material prepared in Example 1, specifically as follows:

[0059] Through a CV test comparison experiment on the sample electrode, compare the electrochemical performance of the electrode, with a potential window of 0~0.6 V and a scanning rate of 10~100 mV·s -1 .

[0060] By conducting GCD test comparison experiments on the sample electrodes, the specific capacitance of the electrodes before and after doping was judged. The current density was 1-10 A·g -1 . The formulas for the mass specific capacity and specific capacitance tested in the three-electrode system are as follows:

[0061] (1)

[0062] (2)

[0063] Q (C·g -1 ) is the mass specific capacity, C (F·g -1 ) is the mass specific capacitance, I (A) is the set current, Δt (s) is the discharge time, m (g) is the mass of the prepared sample, and ΔV is the potential window.

[0064] In this paper, the electrochemical stability of the composite electrodes was studied by the method of constant current charge-discharge cycling tests:

[0065] In Example 1, the CoAl-LDH@Ce-MOF electrode material has a high energy density, power density, and long-term cycling stability. At a current density of 1 A·g -1 , it can provide a high specific capacitance of 3513.3 F·g -1 (as shown in Figure 3 ). The prepared supercapacitor (1×1 cm) was charged for 30 s, and 20 parallel small light bulbs with 2 W could be continuously lit for 10 min, demonstrating its potential in practical applications; in addition, in order to test its long-term static stability, the supercapacitor device was placed for 60 days and then CV tests were carried out. The results showed that CoAl-LDH@Ce-MOF / / AC (activated carbon electrode) could still retain 80% of its initial capacitance, indicating that CoAl-LDH@Ce-MOF has great application prospects as an electrode material for supercapacitors.

[0066] The present invention uses a two-step solvothermal method to prepare the CoAl-LDH@Ce-MOF electrode material. By controlling key factors such as the reaction temperature and reaction time, the reactants are ensured to react fully, thereby forming a composite electrode material with a specific regular morphology and uniform particle size distribution. This method effectively improves the structural consistency and performance of the material and has potential application value.

[0067] Figure 2 Figure 36 shows the cyclic voltammograms of the CoAl-LDH@Ce-MOF electrode material prepared in Example 1 at different scanning rates of 5-100 mV·s -1 . It can be seen from Figure 2 that the electrode material can undergo rapid redox reactions, and it also indicates that electrolyte ions can move rapidly on the electrode surface.

[0068] Figure 3 Specific capacitance variation of the CoAl-LDH@Ce-MOF electrode material prepared in Example 1 at a current density of 1-10 A·g -1 It can be seen from Figure 3 that a high specific capacitance of 3513.3 F·g -1 can be provided at a current density of 1 A·g -1 .

[0069] Figure 4 Cycling performance graph of the CoAl-LDH@Ce-MOF electrode material prepared in Example 1 at a current density of 10 A·g -1 for 5000 cycles. Figure 4 The results show that the CoAl-LDH@Ce-MOF electrode material has excellent cycling stability.

[0070] Figure 5 BET comparison graph of the CoAl-LDH and CoAl-LDH@Ce-MOF electrode materials prepared in Example 1; among them, (a) is CoAl-LDH and (b) is CoAl-LDH@Ce-MOF. It can be seen from Figure 5 that the CoAl-LDH@Ce-MOF electrode material can increase the density of active sites and the rapid transfer / diffusion of electrolyte ions.

[0071] The above-described embodiments are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a 3D hydrangea-shaped electrode material, characterized in that: The following steps are involved: Dissolving Co salt, Al salt, urea and hexadecyltrimethylammonium bromide in water to prepare a mixed solution A; Immersing the substrate in the mixed solution A for hydrothermal reaction at 90-110° C. for 6-7 hours to obtain a substrate with a precursor; Dissolving Ce salt and organic ligand in an organic solvent to prepare a mixed solution B; Immersing the substrate with the precursor in the mixed solution B for hydrothermal reaction at 100-120° C. for 8-10 hours to obtain the 3D hydrangea-shaped electrode material; The molar ratio of the Ce salt to the organic ligand is (0.2-0.25):1; The Ce salt is Ce(NO3)3·6H2O; and the organic ligand is p-aminobenzoic acid.

2. The method for preparing the 3D hydrangea-shaped electrode material according to claim 1, characterized in that: The mass concentration of urea in the mixed solution A is 0.05%-1%; the mass concentration of hexadecyltrimethylammonium bromide in the mixed solution A is 0.01%-0.02%; the concentration of Al salt in the mixed solution A is 0.03 mol / L; and the molar ratio of the Co salt to the Al salt is 3:

1.

3. The method for preparing the 3D hydrangea-shaped electrode material according to claim 1, characterized in that: The Co salt is Co(NO3)2·6H2O; the Al salt is Al(NO3)3·9H2O.

4. The method for preparing the 3D hydrangea-shaped electrode material according to claim 1, characterized in that: The organic solvent is N,N-dimethylformamide; the mass concentration of Ce salt in the mixed solution B is 19-20 mg / mL.

5. The method for preparing the 3D hydrangea-shaped electrode material according to claim 1, characterized in that: The molar ratio of the Co salt to the organic ligand is (0.28-0.32):

1.

6. A 3D hydrangea-shaped electrode material prepared according to the preparation method according to any one of claims 1 to 5.

7. Use of the 3D hydrangea-shaped electrode material as claimed in claim 6 in a supercapacitor.

8. A supercapacitor, characterized in that: The electrode material comprises the 3D hydrangea-shaped electrode material according to claim 6.

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