A potassium-doped modified cobalt-nickel bimetallic organic framework CoNi-MOF-K, a preparation method and application thereof
By doping CoNi-MOFs with potassium ions, a three-dimensional microsphere structure of CoNi-MOF-K was prepared, which solved the problem of poor electrochemical performance of bimetallic MOF materials and achieved high specific capacitance and good electrochemical performance, making it suitable for supercapacitors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GUILIN UNIV OF ELECTRONIC TECH
- Filing Date
- 2023-12-12
- Publication Date
- 2026-06-23
AI Technical Summary
Existing bimetallic MOF materials in supercapacitors suffer from limited metal active sites and low conductivity, resulting in poor electrochemical performance.
Potassium ions were doped into CoNi-MOFs to prepare potassium-doped modified cobalt-nickel bimetallic organic framework CoNi-MOF-K via a one-step hydrothermal method, forming a three-dimensional microsphere structure. The surface of the microspheres is composed of dense pores formed by nanosheets, which improves the electrical conductivity and Faraday reaction active sites of the material.
The preparation process has been simplified, the electrochemical performance of the material has been improved, and higher specific capacitance and capacitance retention rate have been achieved, making it suitable for the field of supercapacitors.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of supercapacitor technology, specifically to a potassium-doped modified cobalt-nickel bimetallic organic framework CoNi-MOF-K, its preparation method, and its applications. Background Technology
[0002] In supercapacitor materials, metal-organic frameworks (MOFs) have become a commonly used architecture for constructing high-performance electrode materials due to their uniformly distributed metal active sites, diverse coordination environments, controllable morphology and structural synthesis, and versatility that can reduce processing costs. The basic principle is that the multidimensional network structure formed by the metal and organic ligands exhibits porous characteristics, allowing for rapid transport of electrolyte ions and their binding to the metal active sites.
[0003] Current research indicates that bimetallic MOFs can provide higher capacitance performance compared to conventional single-metal MOFs due to the synergistic effect between multiple metals. For example, in existing technology 1, Hang XX et al. (《From Co-MOF to CoNi-MOF to Ni-MOF: a facile synthesis of 1D micro- / nanomaterials》InorganicChemistry, 2021, 60(17): 13168-13176. DOI: 10.1021 / acs.inorgchem.1c01561) prepared a rod-shaped bimetallic metal-organic framework CoNi-MOF by simple stirring and standing. Due to the synergistic effect of the organic ligand connecting the two metal ions, this technology enables the electrode to achieve higher capacitance performance at a current density of 0.5 A•g -1 At that time, its specific capacitance can reach 597 F•g -1 The value is much higher than that of Co-MOFs, which have a F•g content of 90%. -1 And Ni-MOF 379 F•g -1 Furthermore, 5 A•g -1 The capacitance retention rate can reach 93.95% after 4000 charge-discharge cycles. However, there is still room for improvement in this technology. The limited number of metal active sites available for Faraday reactions and the low conductivity result in poor electrochemical performance.
[0004] To improve the conductivity of MOFs, increase the number of metal active sites for Faraday reactions, and enhance electrochemical performance, one solution is to incorporate ions or molecules with good conductivity into MOFs. For example, in existing technology 2, Zhu YL et al. (《A metal-organic framework template derived hierarchical Mo-doped LDHs@MOF-Se core-shell array electrode for supercapacitors》Chemical Communications, 2020, 56(89): 13848-13851. DOI: 10.1039 / d0cc05561a) obtained MOF-Se by selenization of CoZn-MOF, and then obtained Mo-doped NiCo-LDH@MOF-Se electrode by electrochemical deposition. Selenization improves the conductivity of MOFs, NiCo-LDH provides a higher specific capacity, and Mo ion doping further enhances the electrochemical activity and conductivity of the material. Therefore, compared with the MOF-Se electrode, its electrochemical performance is significantly improved. At 2mA•cm -2 At that time, the areal density of MOF-Se was only 0.24 C cm⁻¹. -2 However, the Mo-doped NiCo-LDH@MOF-Se has an areal capacity as high as 5.16 C cm⁻¹. -2 However, the problem with this technology is that the entire preparation process is complex and time-consuming, and it cannot guarantee stability during repeated production.
[0005] For example, in existing technology 3, Wang Y et al. (“Controllable preparation of nickel cobaltmannese ternary metal-organic frameworks for high-performance supercapacitor”, Journal of Energy Storage, 2023, 58: 106395. DOI: 10.1016 / j.est.2022.106395) prepared NiCoMn-MOF materials with rod-like structures by incorporating Mn into NiCo-MOFs via a one-step hydrothermal method. The addition of Mn enhanced the stability of the material's cycling structure, thereby improving its electrochemical performance. (The last sentence appears to be incomplete and possibly refers to a specific technology or method.) -1After 3000 charge-discharge cycles, the capacitance retention reached 83.5%, which is higher than that of NiCo-MOFs (62.1%). However, the problem with this technology is that while Mn can replace some Co in the NiCo-MOF lattice and increase the material's cycle stability, it has little effect on improving the capacitance.
[0006] Therefore, based on the aforementioned existing technical solutions, it is clear that bimetallic MOFs, due to the synergistic effect between metals, can provide more redox sites and exhibit superior electrochemical performance. Ion doping in bimetallic MOFs can further enhance the material's electrochemical performance. Summary of the Invention
[0007] The purpose of this invention is to provide a potassium-doped modified cobalt-nickel bimetallic organic framework CoNi-MOF-K, its preparation method, and its applications.
[0008] The present invention addresses the technical problems existing in the prior art by employing the following methods:
[0009] 1. CoNi-MOFs microspheres were prepared using cobalt and nickel as metal center ions;
[0010] 2. The problem of poor electrochemical performance of MOFs can be improved by doping them with potassium ions.
[0011] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:
[0012] A potassium-doped modified cobalt-nickel bimetallic organic framework, CoNi-MOF-K, is synthesized from cobalt acetate, nickel acetate, and 1,2,3,4-butanetetracarboxylic acid. Then, the product is subjected to a hydrothermal reaction with potassium chloride to finally obtain the potassium ion-doped modified cobalt-nickel bimetallic metal-organic framework electrode material, abbreviated as CoNi-MOF-K.
[0013] The CoNi-MOF-K exhibits a three-dimensional microsphere structure with nanosheets forming a dense porous structure on its surface; the electrode material has a specific surface area of 24.3-27.4 m². 2 •g -1 .
[0014] A method for preparing a potassium-doped modified cobalt-nickel bimetallic organic framework (CoNi-MOF-K) includes the following steps:
[0015] Step 1, Preparation of CoNi-based precursor solution: First, cobalt acetate and nickel acetate are dissolved in N,N-dimethylacetamide (DMAC) to obtain a mixed salt solution. At the same time, 1,2,3,4-butanetetracarboxylic acid is dissolved in DMAC to obtain a ligand solution. Then, the ligand solution is quickly poured into the mixed salt solution and stirred to obtain the CoNi-based precursor solution.
[0016] In step 1, the molar ratio of cobalt acetate, nickel acetate, and 1,2,3,4-butanetetracarboxylic acid is 1:(3-4):1;
[0017] Step 2, preparation of CoNi-MOF-K: First, potassium chloride is added to the CoNi-based precursor solution obtained in Step 1 and stirred to dissolve, thus obtaining a reaction solution. Then, under certain conditions, the reaction solution is subjected to a hydrothermal reaction. After the reaction is completed, the product is centrifuged and washed under certain conditions, and then dried under certain conditions to obtain a potassium ion-doped modified cobalt-nickel bimetallic organic framework, abbreviated as CoNi-MOF-K. Among them, the CoNi-MOF-K obtained in Example 1 is named CoNi-MOF-K-35.
[0018] In step 2, the amount of potassium chloride added satisfies the cobalt-potassium metal ratio of 1:(0.34-0.54).
[0019] In step 2, the hydrothermal reaction conditions are: hydrothermal temperature of 160-180 ℃ and hydrothermal time of 20-24 h.
[0020] In step 2, the centrifugation conditions are: centrifugation speed of 5000 rpm, centrifugation time of 5 min, and centrifugation times of 3-5.
[0021] In step 2, the drying conditions are: a drying temperature of 60-80 ℃ and a drying time of 8-12 h.
[0022] An application of a potassium-doped modified cobalt-nickel bimetallic organic framework (CoNi-MOF-K) as a supercapacitor was demonstrated, exhibiting charge-discharge performance within the 0–0.55 V range at a current density of 1 A•g. -1 At that time, the specific capacity reached 900-1400 F•g -1 ; in 8 A•g -1 At that time, the capacitance retention rate was 72%.
[0023] The present invention has been tested using EDS, XRD, SEM, BET, pore size distribution, GCD, CV, and EIS, and the results show that:
[0024] 1. EDS testing proves that the K element was successfully incorporated into CoNi-MOFs and is evenly distributed.
[0025] 2. XRD tests confirm the successful synthesis of CoNi-MOF. The incorporation of K element improves crystallinity and makes the crystal structure more stable.
[0026] 3. According to SEM testing, CoNi-MOF-K is a three-dimensional microsphere with a particle size of 900 nm. The surface of the microsphere is composed of nanosheets, forming a dense porous structure.
[0027] 4. Based on BET and pore size distribution tests, prove that K + There are two forms in which it exists in materials: one is to replace the position of Co / Ni and enter the crystal structure; the other is to be embedded in the pores of the material.
[0028] 3. Based on GCD, CV, and EIS electrochemical tests, it is demonstrated that CoNi-MOF-K can be charged and discharged in the range of 0~0.55 V with a current density of 1 A•g. -1 At that time, the specific capacitance reached 1453 F•g -1 ;8 A•g -1 Relative to 1 A•g -1 It retains 72% of its specific capacitance and has good ionic conductivity.
[0029] Compared with the prior art, the present invention has the following advantages:
[0030] 1. This preparation method adopts a one-step hydrothermal method, which is simple and easy to operate, and the composite material has good electrochemical performance in supercapacitors.
[0031] 2. During the charging and discharging process, the pre-doped potassium ions can replenish the irreversible potassium ions in the electrolyte in a timely manner, thereby enabling rapid ion intercalation and stripping to achieve better electrochemical performance.
[0032] Therefore, compared with the prior art, the present invention has a simpler preparation process, improves the electrochemical performance of composite material electrodes, and has broad application prospects in the field of supercapacitors. Attached Figure Description
[0033] Figure 1 EDS image of CoNi-MOF-K-35 in Example 1;
[0034] Figure 2 The XRD patterns of each sample in Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 are shown.
[0035] Figure 3 Here is a SEM image of CoNi-MOF-K-35 from Example 1;
[0036] Figure 4The BET specific surface area test graphs for Example 1 and Comparative Example 1 are shown.
[0037] Figure 5 These are pore size distribution test diagrams for Example 1 and Comparative Example 1;
[0038] Figure 6 The GCD diagrams of CoNi-MOF-K-35 as the cathode material in Example 1 are shown at different current densities.
[0039] Figure 7 The CV curves for CoNi-MOF-K-35 as the cathode material in Example 1 are shown at different scan rates.
[0040] Figure 8 This is a graph showing the relationship between the specific capacitance and current density of CoNi-MOF-K-35 in Example 1;
[0041] Figure 9 The samples in Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 were measured at 1 A•g. -1 GCD plot;
[0042] Figure 10 The AC impedance diagrams are for each sample in Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4. Detailed Implementation
[0043] The present invention will be further described in detail through embodiments and with reference to the accompanying drawings, but this is not intended to limit the scope of the invention.
[0044] Example 1
[0045] A method for preparing a potassium-doped modified cobalt-nickel bimetallic organic framework (CoNi-MOF-K) includes the following steps:
[0046] Step 1, Preparation of CoNi-based precursor solution: First, 1 mmol of cobalt acetate and 4 mmol of nickel acetate were dissolved in 25 mL of N,N-dimethylacetamide (DMAC) to obtain a mixed salt solution. At the same time, 1 mmol of 1,2,3,4-butanetetracarboxylic acid was dissolved in 15 mL of DMAC to obtain a ligand solution. Then, the ligand solution was quickly poured into the mixed salt solution and stirred for 30 min to obtain the CoNi-based precursor solution.
[0047] Step 2, Preparation of CoNi-MOF-K: First, 35 mg of potassium chloride was added to the CoNi-based precursor solution obtained in Step 1 and stirred to dissolve, thus obtaining a reaction solution. Then, the reaction solution was subjected to a hydrothermal reaction at a hydrothermal temperature of 160 °C for 24 h. After the reaction was completed, the product was centrifuged and washed at a centrifuge speed of 5000 rpm for 5 min and 3 times. After drying at a drying temperature of 60 °C for 8 h, the potassium-doped modified cobalt-nickel bimetallic organic framework CoNi-MOF-K, abbreviated as CoNi-MOF-K, was obtained. The CoNi-MOF-K obtained in Example 1 was named CoNi-MOF-K-35.
[0048] To demonstrate the successful doping of potassium (K) in CoNi-MOF-K-35, EDS (electrode chromatography-mass spectrometry) tests were performed. The test results are as follows: Figure 1 As shown, CoNi-MOF-K-35 contains Ni, Co, and K elements, and the distribution of K coincides with that of O, Ni, and Co elements. Test results indicate that K is successfully incorporated into CoNi-MOFs and is uniformly distributed.
[0049] To further confirm the composition of CoNi-MOF-K-35, XRD tests were performed. The test results are as follows: Figure 2 As shown, the diffraction peaks of CoNi-MOF-K-35 are similar to the standard peaks of CoNi-MOF. However, the diffraction peaks show a shift towards lower angles. This is because K... + This is due to the doping of the crystal lattice structure. Test results show that CoNi-MOF-K-35 was successfully prepared.
[0050] To verify the microstructure of the obtained CoNi-MOF-K-35, SEM testing was performed. The test results are as follows: Figure 3 As shown, the microstructure of CoNi-MOF-K-35 is a three-dimensional microsphere with a particle size of 900 nm. The surface of the microsphere is composed of nanosheets, forming a dense porous structure.
[0051] To demonstrate the effect of potassium (K) on the pore structure of the material, the BET specific surface area of CoNi-MOF-K-35 was tested. The test results are as follows: Figure 4 As shown, CoNi-MOF-K-35 exhibits a typical Type IV isotherm with a specific surface area of 24.3 m². 2 •g -1 Pore distribution test results are as follows: Figure 5As shown, CoNi-MOF-K-35 exhibits mesopores of 4 nm. The test results indicate that the porous structure of CoNi-MOF-K-35 facilitates the diffusion of electrolyte ions and electron transport.
[0052] Taking CoNi-MOF-K-35 as an example, the specific method for preparing the supercapacitor electrode used in the electrochemical testing of this invention is as follows: First, 0.008 g CoNi-MOF-K-35, 0.001 g acetylene black, 0.001 g polytetrafluoroethylene and 0.5 mL ethanol are mixed and ground. After grinding, the mixture is dried under room temperature and air conditions to obtain the electrode material. Then, the electrode material is placed on a 2 cm × 4 cm nickel foam current collector. Finally, the nickel foam is folded in half and pressed under a pressure of 5 kPa to obtain the supercapacitor electrode.
[0053] To demonstrate the specific capacitance performance of CoNi-MOF-K-35, a GCD test was performed. The test results are as follows: Figure 6 As shown, within the charge / discharge range of 0~0.55 V, the GCD curve of CoNi-MOF-K-35 exhibits a clear charge / discharge plateau; when the current density is 1 A•g -1 At that time, its specific capacitance reached 1453 F•g -1 .
[0054] To demonstrate the electrochemical behavior of CoNi-MOF-K-35, CV testing was performed. The test results are as follows: Figure 7 As shown, its redox peaks are more pronounced at lower scan rates, exhibiting typical pseudocapacitive behavior and good reversibility. With increasing scan rate, the CV area increases, and the peak current rises. Test results indicate that CoNi-MOF-K-35 possesses good rate performance.
[0055] To further demonstrate the rate performance of CoNi-MOF-K-35, specific capacitance performance was tested at different current densities. The test results are as follows: Figure 8 As shown, at a current density of 8 A•g -1 At that time, its specific capacitance was 1047 F•g -1 Compared to 1 A•g -1 Under the given conditions, the specific capacitance retention rate was 72%. The test results indicate that CoNi-MOF-K-35 exhibits good rate performance.
[0056] To further investigate the electron transport resistance of CoNi-MOF-K-35, AC impedance testing was conducted. The test results are as follows: Figure 10As shown, the contact resistance Rs of the equivalent circuit of CoNi-MOF-K-35 is 0.33 Ω, and the charge transfer resistance Rct is 0.47 Ω. The test results indicate that CoNi-MOF-K-35 has good ionic conductivity.
[0057] To demonstrate the effect of K on the performance of CoNi-MOF-K, Comparative Example 1 is provided, which is a CoNi-MOF without K doping.
[0058] Comparative Example 1
[0059] A method for preparing CoNi-MOF without K doping is provided. Unless otherwise specified, the steps are the same as in Example 1, except that potassium chloride is not added in step 2. The resulting material is referred to as CoNi-MOF.
[0060] The XRD test results of CoNi-MOF are as follows: Figure 2 As shown, the diffraction peaks of CoNi-MOF are the same as the standard peaks of CoNi-MOF. Combined with the XRD test results of Example 1, it can be seen that CoNi-MOF has an amorphous structure, while CoNi-MOF-K-35 has a crystalline structure, which proves that doping with K can improve crystallinity.
[0061] The BET specific surface area test results of CoNi-MOF are as follows: Figure 4 As shown, the specific surface area of CoNi-MOF is 27.4 m². 2 •g -1 This is a typical Type IV isotherm curve. The pore distribution test results are as follows: Figure 5 As shown, CoNi-MOF exhibits mesopores of 4 nm. Combined with the BET surface area and pore size distribution results from Example 1, it can be seen that K... + It is embedded in the pores of the material without affecting the mesoporous structure.
[0062] Based on the XRD test, BET specific surface area test, and pore distribution test of Example 1, the following conclusions can be drawn: K + There are two forms of existence in materials, which simultaneously play two roles: one is to replace the position of Co / Ni and enter the crystal structure; the other is to embed itself in the pores of the material.
[0063] The GCD test results of CoNi-MOF are as follows: Figure 9 As shown, the GCD curve of CoNi-MOF exhibits a charge-discharge plateau within the charging range of 0~0.55 V; when the current density is 1 A•g -1 At that time, its specific capacitance was 942 F•g -1Compared with the test results of Example 1, it can be seen that the electrode material has poor crystallinity and fewer redox active sites due to the lack of potassium chloride doping. Therefore, its electrochemical performance is weaker than that of CoNi-MOF-K-35, which proves that doping with potassium can improve electrochemical performance.
[0064] The AC impedance test results of CoNi-MOF are as follows: Figure 10 As shown, the contact resistance Rs of the equivalent circuit of CoNi-MOF is 0.35 Ω, and the charge transfer resistance Rct is 0.48 Ω.
[0065] To demonstrate the effect of K doping amount on the performance of CoNi-MOF-K, Comparative Examples 2, 3, and 4 are provided, with CoNi-MOF-K having cobalt-potassium metal ratios of 1:0.34, 1:0.4, and 1:0.54, respectively.
[0066] Comparative Example 2
[0067] A method for preparing CoNi-MOF-K with a cobalt-potassium metal ratio of 1:0.34 is the same as that in Example 1 unless otherwise specified, except that in step 2, the amount of potassium chloride added is 25 mg, and the resulting material is referred to as CoNi-MOF-K-25.
[0068] The XRD test results of CoNi-MOF-K-25 are as follows: Figure 2 As shown, the diffraction peaks of CoNi-MOF-K-25 are similar to the standard peaks of CoNi-MOF, indicating that the degree of crystallinity is still relatively low. The test results support the conclusion that doping with K can improve crystallinity.
[0069] The GCD test results of CoNi-MOF-K-25 are as follows: Figure 9 As shown, the GCD curve of CoNi-MOF-K-25 exhibits a charge-discharge plateau within the charge-discharge range of 0~0.55 V; when the current density is 1 A•g -1 At that time, its specific capacitance reached 998 F•g -1 Compared with the test results of Example 1, it can be seen that due to insufficient potassium chloride doping, the CoNi-MOF-K-25 electrode material has fewer redox active sites and its electrochemical performance is weaker than that of CoNi-MOF-K-35. This proves that doping with potassium can improve electrochemical performance.
[0070] The AC impedance test results of CoNi-MOF-K-25 are as follows: Figure 10 As shown, the contact resistance Rs of the equivalent circuit of CoNi-MOF-K-25 is 0.28 Ω, and the charge transfer resistance Rct is 0.74 Ω.
[0071] Comparative Example 3
[0072] A method for preparing CoNi-MOF-K with a cobalt-potassium metal ratio of 1:0.4 is provided. Unless otherwise specified, the steps are the same as in Example 1, except that the amount of potassium chloride added in step 2 of step 1 is 30 mg. The resulting material is referred to as CoNi-MOF-K-30.
[0073] The XRD test results of CoNi-MOF-K-30 are as follows: Figure 2 As shown, the diffraction peaks of CoNi-MOF-K-25 are similar to those of CoNi-MOF, but the crystallinity is improved. This supports the conclusion that doping with K can increase the crystallinity of the material.
[0074] The GCD test results of CoNi-MOF-K-30 are as follows: Figure 9 As shown, its GCD curve exhibits a clear charge-discharge plateau within the charge-discharge range of 0~0.55 V; when the current density is 1 A•g -1 At that time, its specific capacitance reached 1120 F•g -1 Compared with the test results of Example 1, the electrochemical performance of CoNi-MOF-K-25 is weaker than that of CoNi-MOF-K-35. This proves that doping with potassium can improve electrochemical performance.
[0075] The AC impedance test results of CoNi-MOF-K-30 are as follows: Figure 10 As shown, the contact resistance Rs of the equivalent circuit of CoNi-MOF-K-30 is 0.31 Ω, and the charge transfer resistance Rct is 0.51 Ω.
[0076] Comparative Example 4
[0077] A method for preparing CoNi-MOF-K with a cobalt-potassium metal ratio of 1:0.54 is the same as that in Example 1 unless otherwise specified, except that the amount of potassium chloride added in step 2 is 40 mg, and the resulting material is referred to as CoNi-MOF-K-40.
[0078] The XRD test results of CoNi-MOF-K-40 are as follows: Figure 2 As shown, the diffraction peaks of CoNi-MOF-K-40 are similar to those of CoNi-MOF, but the degree of crystallinity is significantly improved, further confirming that the amount of K doping can improve the crystallinity of the material and make the crystal structure more stable.
[0079] The XRD test results of Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 show that the incorporation of K element improves crystallinity and makes the crystal structure more stable.
[0080] The GCD test results of CoNi-MOF-K-40 are as follows: Figure 9 As shown, the electrode material exhibits a distinct charge-discharge plateau within the 0–0.55 V range; when the current density is 1 A•g -1 At that time, its specific capacitance is 10¹⁰ F•g -1 Compared with the test results of Example 1, it can be seen that due to the excessive amount of potassium chloride doping, the crystal structure is more stable, and therefore the electrochemical performance is weaker than that of CoNi-MOF-K-35.
[0081] The AC impedance test results of CoNi-MOF-K-40 are as follows: Figure 10 As shown, the contact resistance Rs of the equivalent circuit of CoNi-MOF-K-40 is 0.34 Ω, and the charge transfer resistance Rct is 0.61 Ω.
[0082] Based on the conclusions drawn from XRD and BET test results, and combined with the AC impedance test results of Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4, the following conclusions can be drawn:
[0083] The phenomenon that the charge transfer resistance increases when the amount of K element doping is small indicates that K atoms mainly enter the crystal lattice.
[0084] The phenomenon that the charge transfer resistance gradually decreases as the doping amount of K increases indicates that K atoms mainly fill the pores.
[0085] Finally, the phenomenon that the charge transfer resistance increases again when the K element doping amount is too high indicates that after the pores are filled with K atoms, K atoms mainly enter the crystal lattice, resulting in an overly stable crystal structure.
Claims
1. A potassium-doped modified cobalt-nickel bimetallic organic framework CoNi-MOF-K, characterized in that: CoNi-MOF was synthesized from cobalt acetate, nickel acetate, and 1,2,3,4-butanetetracarboxylic acid. Then, the product was subjected to a hydrothermal reaction with potassium chloride to finally obtain a potassium ion-doped modified cobalt-nickel bimetallic organic framework, abbreviated as CoNi-MOF-K. The molar ratio of cobalt acetate, nickel acetate, and 1,2,3,4-butanetetracarboxylic acid is 1:(3-4):1; The amount of potassium chloride added should meet the requirement that the cobalt-potassium metal ratio is 1:(0.34-0.54).
2. The potassium-doped modified cobalt-nickel bimetallic organic framework CoNi-MOF-K according to claim 1, characterized in that: The CoNi-MOF-K exhibits a three-dimensional microsphere structure with nanosheets forming a dense porous structure on its surface; the specific surface area of the CoNi-MOF-K is 24.3-27.4 m². 2 •g -1 .
3. A method for preparing potassium-doped modified cobalt-nickel bimetallic organic framework CoNi-MOF-K, characterized in that... Includes the following steps: Step 1, Preparation of CoNi-based precursor solution: First, cobalt acetate and nickel acetate are dissolved in N,N-dimethylacetamide (DMAC) to obtain a mixed salt solution. At the same time, 1,2,3,4-butanetetracarboxylic acid is dissolved in DMAC to obtain a ligand solution. Then, the ligand solution is quickly poured into the mixed salt solution and stirred to obtain the CoNi-based precursor solution. Step 2, preparation of CoNi-MOF-K: First, potassium chloride is added to the CoNi-based precursor solution obtained in Step 1 and stirred to dissolve to obtain a reaction solution. Then, under certain conditions, the reaction solution is subjected to a hydrothermal reaction. After the reaction is completed, the product is centrifuged and washed under certain conditions, and then dried under certain conditions to obtain the potassium ion-doped modified cobalt-nickel bimetallic organic framework, abbreviated as CoNi-MOF-K. In step 1, the molar ratio of cobalt acetate, nickel acetate, and 1,2,3,4-butanetetracarboxylic acid is 1:(3-4):1; In step 2, the amount of potassium chloride added satisfies the cobalt-potassium metal ratio of 1:(0.34-0.54).
4. The preparation method according to claim 3, characterized in that: In step 2, the hydrothermal reaction conditions are: hydrothermal temperature of 160-180 ℃ and hydrothermal time of 20-24 h. In step 2, the centrifugation conditions are: centrifugation speed of 5000 rpm, centrifugation time of 5 min, and centrifugation times of 3-5. In step 2, the drying conditions are: a drying temperature of 60-80 ℃ and a drying time of 8-12 h.
5. The potassium-doped modified cobalt-nickel bimetallic organic framework CoNi-MOF-K according to claim 1, characterized in that: As a supercapacitor, it is charged and discharged within the range of 0–0.55 V at a current density of 1 A•g. -1 At that time, the specific capacity reached 900-1400 F•g -1 .
6. The potassium-doped modified cobalt-nickel bimetallic organic framework CoNi-MOF-K according to claim 1, characterized in that: As a supercapacitor, in 8 A•g -1 At that time, the capacitance retention rate was 72%.