Nanometer cage-shaped Co3O4 / CoSe / NF composite electrode and preparation method and application thereof
The nanocage-shaped Co3O4/CoSe/NF composite electrode addresses conductivity and lattice distortion issues by integrating nano-needle-shaped Co3O4 with CoSe on nickel foam, achieving high specific capacitance and improved electrochemical performance for supercapacitors.
Patent Information
- Application Number
- CN202411350058.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-26
- Publication Date
- 2024-12-13
AI Technical Summary
Co3O4, when used as the only active substance in electrode materials, struggles with poor conductivity and lattice distortion, limiting its specific capacitance to below 1000F/g, making it unsuitable for high energy density supercapacitors.
A nanocage-shaped Co3O4/CoSe/NF composite electrode is prepared by loading nano-needle-shaped basic cobalt carbonate on nickel foam via a hydrothermal method, forming a ZIF-67 structure, and calcining with Se powder to create a unique nanocage structure that enhances electron transfer and stability.
The composite electrode achieves high specific capacitance and improved charge transfer capacity, with a unique nanocage structure that buffers volume changes during charging and discharging, resulting in enhanced electrochemical performance and lower production costs.
Smart Images
Figure CN119132844A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of electrochemical energy storage, and in particular to a nano-cage Co3O4 / CoSe / NF composite electrode and a preparation method and application thereof. Background Art
[0002] The conversion and storage of electrochemical energy plays an important role in solving the problems of fossil combustion and global warming. Batteries and supercapacitors are considered to be the two best technologies for electrochemical energy storage systems. Supercapacitors have become a research hotspot for electrochemical energy storage due to their advantages of high power density, fast charging capability, long cycle life and cost-effectiveness, but they have the problem of low energy density.
[0003] Redox pseudocapacitance is an electrochemical phenomenon that occurs on the electrode surface or inside the electrode material, specifically, the electrolyte ions undergo a redox reaction with the electrode material. This reaction occurs not only on the electrode surface, but also throughout the electrode, so redox pseudocapacitance can significantly improve the energy density of supercapacitors. Therefore, in order to solve the problem of low energy density of supercapacitors, improvements can be achieved by loading pseudocapacitive materials such as transition metal oxides, sulfides and selenides on nickel foam.
[0004] Co3O4 has the characteristics of diverse oxidation states, simple preparation method and high theoretical specific capacity, but it has poor conductivity and lattice distortion during the cycle process, making it difficult to exert the theoretical specific capacity. If Co3O4 is simply used as the only active substance of the electrode material, the specific capacitance of the electrode material is unsatisfactory and it is difficult to exceed 1000F / g. Summary of the invention
[0005] The problem in the prior art is that if Co3O4 is used as the only active substance of the electrode material, the specific capacitance of the obtained electrode material is difficult to reach 1000F / g. In view of the above problem, the present invention provides a nanocage-shaped Co3O4 / CoSe / NF composite electrode, and the preparation method thereof comprises the following steps:
[0006] (1) nano-needle-shaped basic cobalt carbonate is loaded on the surface of pretreated nickel foam (NF) by a hydrothermal method to obtain a CCH / NF precursor;
[0007] (2) The Co metal ions in the CCH / NF precursor structure and dimethylimidazole form the ZIF-67 structure through coordination;
[0008] (3) The ZIF-67 / CCH / NF precursor and Se powder are placed in a tube furnace for high-temperature calcination. After calcination, a Co3O4 / CoSe / NF composite electrode is obtained.
[0009] Preferably, the specific method of step (1) comprises the following steps:
[0010] S1, dissolving cobalt nitrate hexahydrate and urea in deionized water to prepare a mixed solution, wherein the molar ratio of cobalt nitrate hexahydrate to urea is 1:2;
[0011] S2, adding the pretreated nickel foam and the mixed solution obtained in step S1 into a high-pressure reactor, and performing a hydrothermal reaction at 100-140° C. for 8-12 hours. After the reaction, the obtained product is washed with ethanol and deionized water in turn and vacuum dried to obtain a CCH / NF precursor.
[0012] Preferably, dimethylimidazole and hexamethylenetetramine are dissolved in an ethanol aqueous solution to obtain a mixed solution, and then the CCH / NF precursor is immersed in the mixed solution and mixed evenly, and after standing for a period of time at room temperature, the reaction product is washed with deionized water and vacuum dried to obtain a ZIF-67 / CCH / NF precursor;
[0013] The mass ratio of dimethylimidazole to hexamethylenetetramine is 0.8-1:0.1-0.2;
[0014] The mass concentration of dimethylimidazole in the ethanol aqueous solution is 0.8-1 g / mL.
[0015] Preferably, the calcination temperature in step (3) is 300-400° C., and the holding time is 1-3 h.
[0016] Preferably, the method for pretreating nickel foam in step (1) comprises the following steps:
[0017] The nickel foam was placed in 3M hydrochloric acid aqueous solution, acetone, anhydrous ethanol and deionized water for ultrasonic pretreatment for 30 minutes at an ultrasonic frequency of 20-40kHz. After being taken out, it was vacuum dried at 60-80°C for 7-9 hours.
[0018] Preferably, in step (3), the mass ratio of ZIF-67 / CCH / NF precursor to Se powder is 1:1-20.
[0019] The present invention has the following beneficial effects:
[0020] (1) The present invention grows nano needle-shaped basic cobalt carbonate on the surface of nickel foam by a hydrothermal method. The nano needle-shaped basic cobalt carbonate has a stronger binding force with the nickel foam, and the nano needle-shaped basic cobalt carbonate is not easy to fall off from the surface of the nickel foam. The special needle-shaped structure of the nano needle-shaped basic cobalt carbonate provides a large number of nucleation sites for the generation of ZIF-67, which can effectively avoid the accumulation of ZIF-67, and is beneficial to improving the transmission performance of electrons;
[0021] (2) The Co3O4 / CoSe / NF composite electrode obtained in the present invention has a unique nanocage structure, which can effectively buffer the volume change caused by the charge and discharge process and has better charge and discharge cycle stability;
[0022] (3) The Co3O4 / CoSe / NF composite electrode obtained in the present invention has the characteristics of high specific capacitance of Co3O4 and high electronic conductivity of CoSe. Co3O4 and CoSe work together effectively to significantly enhance the charge transfer capacity and specific capacitance of the composite electrode material, which is very beneficial to improving the electrochemical performance of the supercapacitor.
[0023] (4) In the process of preparing the Co3O4 / CoSe / NF composite electrode, the present invention eliminates the traditional active material coating process, the experimental process is easier to implement and operate, and the production cost is lower, which is conducive to the promotion and application of the material in energy storage devices. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 : These are SEM images of CCH / NF, ZIF-67 / CCH / NF precursor, and Co3O4 / CoSe / NF-5 obtained in Example 1.
[0025] Figure 2 : This is the EDS image of Co3O4 / CoSe / NF-5 obtained in Example 1.
[0026] Figure 3 : is the XRD pattern of Co3O4 / CoSe / NF-5 obtained in Example 1.
[0027] Figure 4 : This is the N2 adsorption-desorption isotherm curve of Co3O4 / CoSe / NF-5 obtained in Example 1.
[0028] Figure 5 : is the CV curve diagram of Co3O4 / CoSe / NF-5 obtained in Example 1 at different scanning speeds.
[0029] Figure 6 : is a GCD curve diagram of Example 1 and Comparative Examples 1-2 respectively tested at a current density of 1 A / g.
[0030] Figure 7 : is the GCD curve diagram of Examples 1-4 respectively tested at a current density of 1 A / g. DETAILED DESCRIPTION
[0031] The present invention is described in detail below with reference to the examples. However, it should be understood that the following examples are only illustrative of the embodiments of the present invention, and are not intended to limit the scope of the present invention.
[0032] Example 1
[0033] A nanocage-shaped Co3O4 / CoSe / NF composite electrode, the preparation method of which is as follows:
[0034] (1) NF (10 cm × 10 cm × 0.1 cm) was cut into a size of 1 × 3 cm, and then the NF was placed in a 3 M hydrochloric acid aqueous solution, acetone, anhydrous ethanol, and deionized water for ultrasonic pretreatment for 30 min at an ultrasonic frequency of 30 kHz. After being taken out, the NF was placed in a vacuum dryer at 60 °C for 8 h.
[0035] (2) At room temperature, cobalt nitrate hexahydrate (5 mmol, 1.455 g) and urea (10 mmol, 0.6 g) were dissolved in 25 mL of deionized water to obtain a plum-red mixed solution;
[0036] (3) placing the NF pretreated in step (1) in a high-pressure reactor, and then pouring the mixed solution obtained in step (2) into the reactor, the NF is completely immersed in the solution, and then subjected to a hydrothermal reaction at 110° C. for 10 h and then taken out, the product is washed three times with ethanol and deionized water respectively, and finally vacuum dried to obtain a CCH / NF precursor;
[0037] (4) Dissolve dimethylimidazole (0.82 g) and hexamethylenetetramine (0.14 g) in a mixed solution of 5 mL of deionized water and 5 mL of anhydrous ethanol, mix them uniformly by ultrasonication at room temperature, and then immerse the CCH / NF precursor obtained in step (3) in the obtained mixed solution. Let it stand at room temperature for 12 h. Wash the obtained product with ethanol and deionized water three times respectively, and then obtain ZIF-67 / CCH / NF precursor after vacuum drying. At this time, the loading amount of the foam nickel surfactant is 4.5 mg / cm 2 ;
[0038] (5) Then, the ZIF-67 / CCH / NF precursor and Se powder were placed in the downstream and upstream of the tube furnace at a mass ratio of 1:5, respectively, and heated to 350°C at 3°C / min under a nitrogen atmosphere and kept at this temperature for 2 h, and then naturally cooled to room temperature to obtain a Co3O4 / CoSe / NF composite electrode, which was recorded as Co3O4 / CoSe / NF-5. At this time, the loading amount of the nickel foam surfactant was 2.9 mg / cm 2 .
[0039] The surface morphology of CCH / NF obtained in Example 1 is as shown in the attached specification. Figure 1 As shown in Figures a and b, pine needle-like basic cobalt carbonate grows evenly on the nickel foam substrate.
[0040] The surface morphology of the ZIF-67 / CCH / NF precursor obtained in Example 1 is as shown in the attached specification. Figure 1As shown in Figures c and d, ZIF-67 is uniformly loaded on the pine needle-shaped basic cobalt carbonate without agglomeration, showing a unique cage-like morphology.
[0041] The surface morphology of Co3O4 / CoSe / NF-5 obtained in Example 1 is shown in the attached specification. Figure 1 As shown in Figures e and f, the surface of Co3O4 / CoSe / NF-5 becomes rough, and the volume of ZIF-67 is significantly reduced, but the cage-like morphology is still retained. After calcination, there is no obvious shedding of Co3O4 / CoSe on NF, indicating that there is good adhesion between Co3O4 / CoSe and NF.
[0042] The EDS test results of Co3O4 / CoSe / NF-5 obtained in Example 1 are shown in the attached specification. Figure 2 As shown, the test results show that Co3O4 / CoSe / NF-5 contains Co element, O oxygen element and Se element, and each element is evenly distributed in the entire nanostructure.
[0043] The XRD test results of Co3O4 / CoSe / NF-5 obtained in Example 1 are shown in the attached specification. Figure 3 The spectrum shows the presence of characteristic diffraction peaks of Co3O4 and CoSe, indicating that the surface of nickel foam is successfully composited with Co3O4 and CoSe.
[0044] The N2 adsorption-desorption isotherm test results of Co3O4 / CoSe / NF-5 obtained in Example 1 are shown in the attached manual. Figure 4 The test results show that the N2 adsorption-desorption isotherm of Co3O4 / CoSe / NF-5 is a typical IV type with an obvious hysteresis loop, indicating that the material is a mesoporous material. The specific surface area of Co3O4 / CoSe / NF-5 is 652.7 m 2 / g, proving that the Co3O4 / CoSe / NF-5 obtained after selenization treatment still retains the structural characteristics of ZIF-67 with large specific surface area.
[0045] The CV curves of Co3O4 / CoSe / NF-5 obtained in Example 1 at different scanning speeds are shown in the attached manual. Figure 5 As shown, there are obvious redox peaks in the CV curve, proving that the Co3O4 / CoSe / NF-5 electrode material is a pseudocapacitive material.
[0046] Example 2 is the same as Example 1, except that the mass ratio of ZIF-67 / CCH / NF precursor to Se powder is 1:1 in Example 2. The obtained composite electrode is recorded as Co3O4 / CoSe / NF-1.
[0047] Example 3 is the same as Example 1, except that the mass ratio of ZIF-67 / CCH / NF precursor to Se powder is 1:10 in Example 3. The obtained composite electrode is recorded as Co3O4 / CoSe / NF-10.
[0048] Example 4 is the same as Example 1, except that the mass ratio of ZIF-67 / CCH / NF precursor to Se powder is 1:20 in Example 4. The obtained composite electrode is recorded as Co3O4 / CoSe / NF-20.
[0049] Comparative Example 1 is the same as Example 1, except that the mass ratio of ZIF-67 / CCH / NF precursor to Se powder in Comparative Example 1 is 1:30. The amount of Se powder is too large, and during the high-temperature calcination process, all the Co oxides in the ZIF-67 / CCH / NF precursor are converted into CoSe. The composite electrode obtained in Comparative Example 1 is recorded as CoSe / NF.
[0050] Comparative Example 2 is the same as Example 1, except that no Se powder is added during the high-temperature calcination in Comparative Example 2. The obtained composite electrode is recorded as Co3O4 / NF.
[0051] Performance Testing
[0052] The three-electrode system was used to test the performance of the composite electrodes obtained in Examples 1-4 and Comparative Examples 1-2. The composite electrodes obtained in Examples 1-4 and Comparative Examples 1-2 were used as working electrodes of the three-electrode system, the counter electrode was a platinum mesh, the reference electrode was a Hg / HgO electrode, the electrolyte was a 3 mol / L potassium hydroxide aqueous solution, and the electrochemical workstation model was Swiss Metrohm (PGSTAT-302N). The GCD curves obtained by testing Examples 1-4 of the present invention at a current density of 1 A / g are shown in the attached manual. Figure 7 The GCD curves obtained by testing Example 1 of the present invention and Comparative Examples 1-2 at a current density of 1 A / g are shown in the attached manual. Figure 6 The specific test results are shown in Table 1.
[0053] Table 1
[0054] Test items Specific capacitance (F / g) Example 1 1841.6 Example 2 1202.4 Example 3 1436 Example 4 1108.2 Comparative Example 1 1086.5 Comparative Example 2 928
[0055] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.
Claims
1. A nanocage-shaped Co3O4 / CoSe / NF composite electrode, characterized in that: The preparation method comprises the following steps: (1) loading nano-needle-shaped basic cobalt carbonate on the surface of pretreated NF by a hydrothermal method to obtain a CCH / NF precursor; (2) The Co metal ions in the CCH / NF precursor structure and dimethylimidazole form the ZIF-67 structure through coordination; (3) The ZIF-67 / CCH / NF precursor and Se powder are placed in a tube furnace for high-temperature calcination. After calcination, a Co3O4 / CoSe / NF composite electrode is obtained.
2. The nanocage-shaped Co3O4 / CoSe / NF composite electrode according to claim 1, characterized in that: The specific method of step (1) comprises the following steps: S1, dissolving cobalt nitrate hexahydrate and urea in deionized water to prepare a mixed solution, wherein the molar ratio of cobalt nitrate hexahydrate to urea is 1:2; S2, immersing the pretreated NF into the mixed solution obtained in step S1 and placing it in a high-pressure reactor for hydrothermal reaction at 100-140° C. for 8-12 hours. After the reaction is completed, the obtained product is washed with ethanol and deionized water in turn and vacuum dried to obtain a CCH / NF precursor.
3. The nanocage-shaped Co3O4 / CoSe / NF composite electrode according to claim 1, characterized in that: Dimethylimidazole and hexamethylenetetramine were dissolved in an ethanol aqueous solution to obtain a mixed solution, and then the CCH / NF precursor was immersed in the mixed solution and mixed evenly. After standing at room temperature for a period of time, the reaction product was washed with deionized water and vacuum dried to obtain a ZIF-67 / CCH / NF precursor.
4. The nanocage-shaped Co3O4 / CoSe / NF composite electrode according to claim 1, characterized in that: The calcination temperature in step (3) is 300-400° C. and the holding time is 1-3 h.
5. The nanocage-shaped Co3O4 / CoSe / NF composite electrode according to claim 1, characterized in that: The method of NF pretreatment in step (1) comprises the following steps: The NF was placed in 3M hydrochloric acid aqueous solution, acetone, anhydrous ethanol and deionized water for ultrasonic pretreatment for 30 minutes at an ultrasonic frequency of 20-40kHz. After being taken out, it was vacuum dried at 60-80°C for 7-9 hours.
6. The nanocage-shaped Co3O4 / CoSe / NF composite electrode according to claim 1, characterized in that: In step (3), the mass ratio of ZIF-67 / CCH / NF precursor to Se powder is 1:1-20.
7. A supercapacitor, characterized in that: A nanocage-shaped Co3O4 / CoSe / NF composite electrode as described in any one of claims 1 to 6 is used as the negative electrode.