Electrode material based on phosphorus-doped metal organic complex, preparation method and application thereof

Abstract

The invention relates to the technical field of electrode materials, in particular to an electrode material based on a phosphorus-doped metal organic complex, a preparation method and application thereof. Transition metal Ni serves as a coordination center and is subjected to coordination reaction with aromatic benzene ring organic ligands to form a metal organic complex, the metal organic complex serves as a head product, phosphorus atoms are doped through a post-modification method, and the heterogeneous heteroatom phosphorus-doped organic complex electrode material is obtained. All indexes of the electrode material are greatly improved unexpectedly on the basis of the original electrochemical performance, moreover, due to the double-coordination effect of the phosphorus element and the transition metal, the specific capacitance of the material can be greatly increased through the brought pseudocapacitance, and therefore the electrode material is an ideal electrode material of a super capacitor and can be applied to different fields.

Description

Technical Field

[0001] This application relates to the field of electrode materials technology, specifically to an electrode material based on phosphorus-doped organometallic complexes, its preparation method, and its application. Background Technology

[0002] Supercapacitors, as a novel type of clean energy storage device, occupy an important position in the field of energy storage due to their significant electrochemical characteristics, fast charging and discharging speed, high safety performance, cost-effective maintenance, and extended cycle life. In recent years, supercapacitor electrode materials such as carbon materials, metal sulfides, metal oxides, and organometallic complexes have been extensively studied. Among them, organometallic complexes are porous functional materials formed by the assembly of metal ions and organic ligands through coordination bonds. Their large specific surface area, tunable size and pore volume, variety, simple synthesis process, and low cost have attracted widespread attention in the energy storage field. However, as electrode materials, organometallic complexes also suffer from low specific capacitance and poor cycle stability, which greatly limits their application in supercapacitors.

[0003] To improve the electrochemical performance of organometallic complexes (MOFs), various doping modification methods have been disclosed in the prior art, including elemental doping and composite doping. In terms of dopant element selection, these methods cover a variety of non-metallic elements such as nitrogen, sulfur, phosphorus, boron, and fluorine, as well as transition metal ions. Doping processes include in-situ blending and coordination, high-temperature calcination doping, solvothermal / hydrothermal post-treatment, plasma doping, and ion exchange doping. However, for different MOFs, the effect of doping modification is influenced by a combination of factors, including the electronic structure of the dopant element, the doping amount, the doping sites, the compatibility of the doping method with the parent structure, and reaction conditions, resulting in highly unpredictable doping effects. In practice, even when choosing the same dopant element, the improvement in electrochemical performance varies significantly depending on the structure of the MOF or the doping process used. Some doping may only slightly improve a single performance indicator, while others may even lead to a decrease in electrochemical performance due to the destruction of the porous structure or active sites of the MOFs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application provides an electrode material based on phosphorus-doped organometallic complexes, its preparation method, and its application.

[0005] To achieve the above objectives, the technical solution of this application is as follows: A method for preparing an electrode material based on phosphorus-doped organometallic complexes, comprising the following steps: (1) Dissolve the organic ligand pyromellitic acid in a mixed solvent of DMF and methanol to obtain solution A; (2) The nickel salt (Ni(NO3)2∙6(H2O)) is dissolved in water and added to solution A to obtain solution Ba; (3) React the solution Ba at 110-130℃ for 8-12 h to obtain the solid initial product C; (4) Disperse the solid initial product C and sodium phosphate dodecahydrate in a mixed solvent of DMF, methanol and water, and react at 110-130℃ for 15-17h to obtain solid product D; (5) Wash and dry the solid product D to obtain the phosphorus-doped organometallic complex electrode material.

[0006] Preferably, the molar ratio of the organic ligand pyromellitic acid to the nickel salt (Ni(NO3)2∙6(H2O)) is 1:1.

[0007] Preferably, in step (2), the aqueous solution of nickel salt is added dropwise to solution A, and after the addition, stirring is continued for 0.5-1.5 hours.

[0008] Preferably, in step (3), solution Ba is reacted in a high-pressure reactor. After the reaction is completed, DMF, methanol and deionized water are used to wash the solution in sequence, and the solution is dried to obtain solid primary product C.

[0009] Preferably, in step (4), the mass ratio of the solid initial product C to sodium dodecahydrate phosphate is 1:1.

[0010] Preferably, in step (5), the solid product D is washed sequentially with DMF, methanol, and deionized water.

[0011] Electrode materials based on phosphorus-doped organometallic complexes were prepared by the method described above.

[0012] The application of phosphorus-doped organometallic complex-based electrode materials in the fabrication of supercapacitors, as described above.

[0013] A supercapacitor employing the phosphorus-doped organometallic complex-based electrode material as described above.

[0014] The beneficial effects are explained as follows: Using transition metal Ni as the coordination center, a coordination reaction occurs with an aromatic benzene ring organic ligand to form a metal-organic complex. Using this metal-organic complex as the initial product, phosphorus atoms are doped through a post-modification method to obtain a heteroatom phosphorus-doped organic complex electrode material. This results in an unexpected and significant improvement in various indicators of the electrode material's original electrochemical performance. Moreover, due to the synergistic effect of phosphorus and transition metal, the resulting pseudocapacitance can greatly increase the specific capacitance of the material. Therefore, it is also an ideal electrode material for supercapacitors and can be applied to different fields.

[0015] The phosphorus-doped organic complex electrode material prepared according to one embodiment of the present invention exhibits a specific capacitance of 126.4 F / g, an energy density of 45.0 Wh / kg, and a power density of 334.5 W / kg at a current density of 10 A / g. After 10,000 charge-discharge cycles, its capacitance retention is 53.25%. Furthermore, by comparing the phosphorus-doped organometallic ligand material of the present invention with its precursor, it can be seen that the phosphorus-doped organometallic ligand material has greater application value under certain conditions. In summary, the preparation method disclosed in the present invention uses ligand raw materials with stable properties and quality. Through the formulation and steps, the required phosphorus-doped organic complex material can be stably produced industrially. The prepared phosphorus-doped organic complex material has stable quality, uniform product structure, and superior performance, and has better application value than the prior art. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0017] Figure 1 XRD comparison images of Ni-TMA and NiP-TMA materials prepared in this invention; Figure 2 SEM images of the Ni-TMA (a) and NiP-TMA (bd) materials of the present invention; Figure 3 The adsorption-desorption isotherms and pore size distribution diagrams of Ni-TMA and NiP-TMA of the present invention are shown below. Figure 4 The XPS full spectrum of the NiP-TMA of the present invention is shown in (a), and the fine spectra of Ni2p, C1s, O1s and P2p are shown in (b), (c), (d) and (e). Figure 5 The CV curves (a) and charge-discharge curves (c) of the Ni-TMA material of the present invention are shown in Figure 10 mV / s to 60 mV / s, and the CV curves (b) and charge-discharge curves (d) of NiP-TMA material are shown in Figure 10 mV / s to 60 mV / s. Figure 6 The specific capacitance of the materials Ni-TMA and NiP-TMA of this invention under different current densities; Figure 7The diagrams (a) and (b) show the Ni-TMA and NiP-TMA diagrams of the materials used in this invention. Figure 8 The materials Ni-TMA and NiP-TMA of this invention are used at a frequency of 1×10⁻⁶. -2 Hz~1×10 5 AC impedance curve (EIS) at Hz; Figure 9 The graph shows the cycle life curves of the materials Ni-TMA and NiP-TMA of this invention at 10 A / g. Detailed Implementation

[0018] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0019] Unless otherwise defined, 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 application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application. The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0020] The following embodiments involve the following chemical materials: ① Benzene-1,3,5-tricarboxylic acid, structural formula ; ②DMF, or N,N-dimethylformamide, is an organic compound with the molecular formula C3H7NO. It is a colorless and transparent liquid. It is both a widely used chemical raw material and a versatile and excellent solvent. Except for halogenated hydrocarbons, it is miscible with water and most organic solvents, and has good solubility for a wide range of organic and inorganic compounds. ③CH3OH, or methanol, is a simple saturated monohydric alcohol with a molecular weight of 30.042. It is a colorless, flammable, and toxic liquid at room temperature and is widely used as a solvent, fuel, and chemical raw material. ④ Nickel nitrate hexahydrate, with the molecular formula Ni(NO3)2∙6(H2O); ⑤ Sodium phosphate dodecahydrate.

[0021] Example 1: ① Weigh out 0.6304 g (3 mmol) of organic ligand. Place benzene-1,3,5-tricarboxylic acid in a 50ml beaker, then add 10ml of DMF and 10ml of methanol. Place the beaker containing the mixture on a magnetic stirrer and stir at a constant temperature until the organic ligand is completely dissolved for 30 minutes to obtain solution A. ② Weigh 0.8724 g (3 mmol) of nickel nitrate hexahydrate according to the molar ratio of metal to organic ligand of 1:1, dissolve it completely in 10 ml of deionized water, add the dissolved nickel nitrate hexahydrate solution to organic mixed solution A (slowly add dropwise), and continue stirring at constant temperature for 1 hour to obtain solution Ba. ③ Transfer the solution Ba from step ② to a 50ml high-pressure reactor, react at 120℃, hydrothermally for 10 hours, cool, rinse with DMF, methanol, and deionized water at least 3 times in sequence, and finally dry the washing product in a 60℃ forced-air drying oven for 10 hours to obtain the green solid primary product C (denoted as Ni-TMA). ④ Take 100 mg of each of the solid initial product C and sodium phosphate dodecahydrate in a mass ratio of 1:1 and place them in a 30 ml mixed solution of (VDMF:VCH3OH:VH2O = 1:1:1). Stir on a magnetic stirrer for 1 h at a constant temperature. Set the reaction oven temperature to 120℃ and react for 16 h to obtain the yellow solid product D. ⑤ The yellow solid product D was washed repeatedly with DMF, methanol and deionized water in sequence. The washed product E was placed in a 60°C drying oven and dried for 12 hours to obtain the target phosphorus-doped organic electrode material (denoted as NiP-TMA).

[0022] like Figure 1 The image shows a comparison of the X-ray diffraction patterns of phosphorus-doped materials Ni-TMA and NiP-TMA. It can be observed that the diffraction peak energies of NiP-TMA are consistent with those of Ni-TMA, and the incorporation of phosphorus enhances its diffraction peaks.

[0023] like Figure 2 It can be seen that Ni-TMA is used as a precursor ( Figure 2 a) By modifying heteroatoms in the post-process, the NiP-TMA prepared by this invention has a needle-like structure with a lot of pores on the material surface. Its material morphology makes it easier to wet when activated in the electrolyte and obtain more specific surface area for charge adsorption, while accelerating the penetration speed of the electrolyte. like Figure 3As shown in (ab), the NiP-TMA material exhibits typical type II adsorption-desorption isotherm characteristics. When the relative pressure is between 0.8 and 1.0, an infinitely rising trend can be observed in the NiP-TMA curve, indicating that it possesses significant mesoporous characteristics. These mesopores provide channels for rapid ion transport. Observing the BJH pore size distribution diagram in the figure, it can be seen that the material also contains a large number of mesopores with an average size of 38.3777 nm. These mesopores can be used as storage sites for electrolyte ions, with a specific surface area of ​​18.2779 m². 2 / g; Figure 3 (cd) It can be observed that this curve also possesses the characteristics of a Type II isotherm curve, as shown in the graph. Figure 3 (d) shows the pore size distribution of Ni-TMA. The figure reveals that Ni-TMA also contains a large number of macropores, with an average pore size of 69.9393 nm. The material has a small specific surface area of ​​2.4676 m². 2 / g, which is related to its high density, as its solvent molecules fill the pores, reducing its surface area.

[0024] Figure 4 The XPS full spectrum of NiP-TMA is shown in (a), and the fine spectra of Ni2p (b), C1s (c), O1s (d) and P2p (e) are shown in (e). Figure 4 (a) It can be seen that the peaks at 874.8, 286.8, 534.8, and 135.8 eV correspond to the peaks of Ni, C, O, and P elements contained in NiP-TMA. From Figure 4 (b) It can be seen that the Ni2P peaks at 856.3 eV and 874.4 eV in the material are characteristic peaks of Ni2p3 / 2 and Ni2p1 / 2, respectively, and the difference between the two characteristic peaks is 20.1 eV, indicating that Ni mainly exists in the divalent form; Figure 4 The fine C1s spectrum in (c) shows that the CC, CO, and C=O bonds on the benzene ring are located at 284.7, 285.1, and 288.7 eV, respectively. Figure 4 (d) The fine spectrum of O element shows that the characteristic peak at 531.3 eV mainly originates from oxygen on the C=O bond of the benzene ring, while the characteristic peak at 532.4 eV mainly involves bound water adsorbed onto the material through physical processes. Figure 4 (e) shows the fine spectrum of the P2p structure, with a characteristic peak at 133.5 corresponding to the PO bond. The heteroatomic phosphorus provides part of the specific capacitance, significantly enhancing the superelectric performance.

[0025] To further explore the applications of Ni-TMA and NiP-TMA electrode materials in energy storage, they were assembled with activated carbon (AC) to form supercapacitors. For example... Figure 5The CV and CP (constant current charge / discharge) curves of the Ni-TMA / / AC and NiP-TMA / / AC devices are displayed. The CV curves also show that... Figure 5 (a) CV curves of Ni-TMA in the range of 10 mV / s to 60 mV / s. Figure 5 (b) The CV curve of Ni-TMA in the range of 10mv / s to 60mv / s shows no significant change, indicating that the assembled device has good stability and excellent charge and discharge performance. Figure 5 (c) shows Ni-TMA and Figure 5 (d) shows the charge-discharge curves of the two NiP-TMA materials at different current densities.

[0026] Table 1. Specific capacitance, energy density, and power density of Ni-TMA Table 2. Specific capacitance, energy density, and power density of NiP-TMA From Table 1-2, Figure 6-7 It can be seen that when the current density is 0.5 A / g, 1 A / g, 2 A / g, 3 A / g, 5 A / g, and 8 A / g, the specific capacitance of Ni-TMA is 77.77 F / g, 62.65 F / g, 50.04 F / g, 42 F / g, 29.37 F / g, and 4.81 F / g, respectively, while the specific capacitance of NiP-TMA is 126.47 F / g, 119.68 F / g, 102.07 F / g, 91.31 F / g, 83.97 F / g, and 75.57 F / g, respectively. In comparison, the specific capacitance of NiP-TMA is significantly higher than that of Ni-TMA. When the current density increases to 8 A / g, the specific capacitance of Ni-TMA remains at 6.18%, while that of NiP-TMA remains at 59.75%. Clearly, NiP-TMA exhibits significantly higher capacitance retention than Ni-TMA, and its energy density and rate performance are also superior. The NiP-TMA material prepared in this invention possesses superior specific capacitance and energy density, and its higher electrochemical performance makes it more suitable for use as an electrode material in supercapacitors.

[0027] like Figure 8 The materials Ni-TMA and NiP-TMA shown are at a frequency of 1×10 -2 Hz~1×10 5 The electrochemical impedance spectroscopy (EIS) curve at Hz. The diameter of the arc in the high-frequency region is related to the conductivity of the material; the smaller the diameter, the higher the conductivity. It also reflects the kinetic interaction between the electrode material and the electrolyte. Figure 6 It can be seen that the diameters of the arcs in the high-frequency region of both curves are relatively small, and the intersections of the arcs with the X-axis are 0.670Ω and 0.414Ω, respectively. This indicates that the internal resistance of the NiP-TMA material is lower than that of Ni-TMA, which also means that Ni-TMA has higher conductivity. The slope of the straight line in the low-frequency region is related to the capacitance performance, and the slope of NiP-TMA is slightly greater than that of Ni-TMA, indicating that the supercapacitor assembled from NiP-TMA / / AC tends to exhibit ideal capacitance behavior.

[0028] Figure 9 The graph shows the charge-discharge cycle life curves of the two materials at 10 A / g. As can be seen from the graph, after 10,000 charge-discharge cycles, the capacitance of Ni-TMA remains at 49.47% of its initial capacitance, while the capacitance of NiP-TMA remains at 53.25%. This indicates that NiP-TMA has a longer lifespan than Ni-TMA, and further proves that NiP-TMA has superior electrochemical performance.

[0029] This invention uses a metal-organic complex prepared from nickel metal and existing ligands as a precursor, and sodium phosphate dodecyl hydrate as a heteroatom source. Phosphorus is incorporated into the metal-organic precursor to prepare NiP-TMA electrode material. The physical properties and structural composition of the NiP-TMA material are studied by physical characterization methods. Detailed electrochemical testing and analysis of NiP-TMA are performed using a two-electrode system.

[0030] (1) Ni-TAM as a precursor has a surface area of ​​2.4676 m². 2 / g, after incorporating heteroatomic phosphorus, the material also exhibits a porous structure, with heteroatoms uniformly distributed on the surface and inner walls of the pores of the NiP-TMA material. BET analysis showed an average mesopore size of 38.3777 nm and a specific surface area as high as 18.2779 m². 2 / g, its large pore size accelerates the penetration speed of the electrolyte and its high specific surface area provides more Faraday reaction sites.

[0031] (2) NiP-TMA also exhibits excellent performance in electrochemical tests. At a current density of 0.5 A / g, its maximum specific capacitance is 126.47 F / g, and at 8 A / g, it still maintains 59.75% of its capacitance. At 0.5 A / g, its maximum energy density is 44.9 Wh / kg, and at 10 A / g, its power density reaches a maximum of 334.46 W / kg. Furthermore, after 10,000 cycles of charge-discharge testing at 10 A / g, NiP-TMA still retains 53.25% of its specific capacitance. The high energy and power densities allow NiP-TMA to undergo rapid charge-discharge at high currents.

[0032] The phosphorus-doped material NiP-TMA prepared by this invention has a rich porous structure and a large specific surface area, which significantly improves its electrochemical performance, especially the energy density and specific capacitance compared to the precursor Ni-TMA material. This indicates that phosphorus plays an important role in improving the electrochemical performance of the material. The phosphorus-doped material prepared by this invention has excellent supercapacitor electrode material performance, with excellent performance in all indicators, and can be used as an ideal practical capacitor electrode material.

[0033] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for producing an electrode material based on a phosphorus-doped metal organic complex, characterized by, The preparation method comprises the following steps: (1) dissolving the organic ligand of trimesic acid in a mixed solvent of DMF and methanol to obtain solution A; (2) dissolving the metal nickel salt (Ni(NO3)2·6(H2O) in water and adding it to solution A to obtain solution Ba; (3) reacting solution Ba at 110-130°C for 8-12h to obtain solid primary product C; (4) dispersing the solid primary product C and sodium phosphate dodecahydrate in a mixed solvent of DMF, methanol and water and reacting at 110-130°C for 15-17h to obtain solid product D; (5) washing and drying the solid product D to obtain the phosphorus-doped metal organic complex electrode material.

2. The method for preparing the electrode material based on phosphorus-doped organometallic complexes according to claim 1, characterized in that: The molar ratio of the organic ligand of trimesic acid to the metal nickel salt (Ni(NO3)2·6(H2O) is 1:

1.

3. The method for preparing the electrode material based on phosphorus-doped organometallic complexes according to claim 1, characterized in that: In step (2), the aqueous solution of the metal nickel salt is added dropwise to solution A, and after the dropwise addition, the stirring is continued for 0.5-1.5h.

4. The method for preparing the electrode material based on phosphorus-doped organometallic complexes according to claim 1, characterized in that: In step (3), solution Ba is reacted in a high-pressure reaction kettle, and after the reaction is completed, DMF, methanol and deionized water are sequentially washed, and the solid primary product C is obtained after drying.

5. The method for preparing the electrode material based on phosphorus-doped organometallic complexes according to claim 1, characterized in that: In step (4), the mass ratio of the solid primary product C to sodium phosphate dodecahydrate is 1:

1.

6. The method for preparing the electrode material based on phosphorus-doped organometallic complexes according to claim 1, characterized in that: In step (5), the solid product D is sequentially washed with DMF, methanol and deionized water.

7. The phosphorus-doped metal organic complex-based electrode material prepared by the preparation method according to any one of claims 1-6.

8. The use of the phosphorus-doped metal organic complex-based electrode material according to claim 7 for preparing a supercapacitor.

9. A supercapacitor using the phosphorus-doped metal organic complex-based electrode material according to claim 7.

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