Cr-MOF / polyaniline composite gel as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of supercapacitor electrode materials, and particularly relates to Cr-MOF / polyaniline composite gel and a preparation method and application thereof. The preparation method of the Cr-MOF / polyaniline composite gel comprises the following steps: in a first solvent system, reacting a chromium source and an organic ligand at 80-160 DEG C to form a continuous three-dimensional network structure, and aging to obtain Cr-MOF gel; the preparation method comprises the following steps: preparing a Cr-MOF gel, soaking the Cr-MOF gel in an aniline solution to enable aniline molecules to be diffused and permeated into gaps of a three-dimensional network structure, then soaking the Cr-MOF gel containing the aniline molecules in an initiator solution to initiate polymerization reaction of the aniline, and generating polyaniline in situ to obtain the Cr-MOF / polyaniline composite gel. The preparation method is simple and suitable for industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of supercapacitor electrode materials, and in particular relates to a Cr-MOF / polyaniline composite gel and a preparation method and application thereof. Background Art

[0002] Supercapacitors are high-power-density energy storage devices with the characteristics of rapid charging and discharging and long cycle life. However, the relatively low energy density limits its overall capacity, thus restricting its wider application. The performance of supercapacitors is significantly affected by the electrode material, so designing economical and efficient electrode materials is crucial to advancing energy storage technology. The full name of metal-organic frameworks in English is metal-organic frameworks, abbreviated as MOFs in English; MOFs are a class of hybrid materials composed of metal nodes or clusters and organic ligands, with advantages such as large specific surface area, high porosity, adjustable pore size, and diverse topological structures. These characteristics make MOFs theoretically have extremely large double-layer capacitance, so MOFs are widely used to develop high-performance supercapacitor materials, but when used alone, they are limited by insufficient conductivity and need to be improved.

[0003] Most existing technologies can significantly improve the electrochemical performance of MOFs by combining them with conductive polymers; Among various conductive polymers, polyaniline (PAI) exhibits pseudocapacitive properties through a fast and reversible redox reaction, enabling additional charge storage via a Faradaic mechanism. The integration of the double-layer capacitance of MOFs with the pseudocapacitance of PAI significantly improves the overall capacitance and energy density, thereby enhancing the specific capacitance. Furthermore, PAI allows the ultra-high surface area of ​​MOFs to be fully utilized, resulting in electrode materials with superior charge transfer properties.

[0004] However, in the existing technology of compounding MOFs with conductive polymers, when the non-in situ physical mixing method is used, the interfacial interaction between MOFs and polymers is weak, resulting in low charge / mass transfer efficiency and insufficient electron transfer pathways during electrode operation; when in situ bonding is used, the MOFs surface lacks specific anchoring points, resulting in uneven distribution of the polymer and clogging of the pores. Summary of the Invention

[0005] In order to solve the technical problems in the above-mentioned prior art that the use of non-in situ physical mixing leads to poor interface contact and low charge transfer efficiency, and the use of in situ binding lacks MOFs surface anchoring points, resulting in uneven distribution of polyaniline and pore blockage, the present invention provides a Cr-MOF / polyaniline composite gel and its preparation method and application.

[0006] The first object of the present invention is to provide a method for preparing a Cr-MOF / polyaniline composite gel, comprising the following steps: In the first solvent system, the chromium source and the organic ligand are placed at 80℃~160℃ to react so that Cr 3+ It coordinates with organic ligands to form a continuous three-dimensional network structure, and after aging, Cr-MOF gel is obtained.

[0007] The Cr-MOF gel is immersed in an aniline solution to allow the aniline molecules to diffuse and penetrate into the gaps of the three-dimensional network structure. Then, the Cr-MOF gel containing aniline molecules is immersed in an initiator solution to allow the initiator to diffuse into the three-dimensional network structure, triggering the polymerization reaction of aniline and generating polyaniline in situ to obtain a Cr-MOF / polyaniline composite gel; the molar ratio of the chromium source to the organic ligand is 3:1 to 6.

[0008] Preferably, the organic ligand is trimesic acid.

[0009] It should be noted that the formation of Cr-MOF gel includes two stages. The first stage is under the condition of reaction temperature of 80℃~160℃. 3+ The ions reacted mildly with the trimesic acid ligands to produce a large number of Cr-MOF primary structural units, which then aggregated into nuclei to obtain discrete but periodically distributed Cr-MOF oligomers. In the second stage, due to the Cr 3+ The ions are hard Lewis acids with high charge density. These oligomeric Cr-MOF clusters carry positive surface charges and contain numerous coordinatively unsaturated Cr(III) metal centers. These coordinatively unsaturated Cr(III) metal centers can undergo hydroxyl or oxybridge reactions via -OH groups or H2O molecules in the solvent. Consequently, the periodically distributed Cr-MOF oligomers can continue to crosslink, connecting to form increasingly larger branched polymers. Ultimately, these polymers extend throughout the entire solution volume and interconnect to form a continuous three-dimensional network. This three-dimensional network encapsulates solvent molecules within its interstices, rendering the entire system fluid, thus forming a Cr-MOF gel.

[0010] It should also be noted that the chromium source and the organic ligand are placed at 80℃~160℃ for reaction. 3+ After the ions are mixed with the organic ligands, an appropriate reaction temperature is required to induce a mild coordination reaction. When the reaction temperature is lower than 80 °C, Cr 3+ The ions cannot react with trimesic acid to form a complex, and only a clear and transparent mixed solution can be obtained. When the reaction temperature is higher than 160℃, Cr 3+ The coordination reaction between ions and trimesic acid is too intense, resulting in excessive and rapid growth of Cr-MOF crystal nuclei, which eventually aggregate rapidly to form precipitates and cannot obtain a gel.

[0011] Preferably, the molar ratio of the chromium source to the organic ligand is 3:1-6; within this molar ratio range, Cr 3+ The number of organic ligands is close to that of the Cr-MOF oligomers formed after coordination, which occupies a dominant position in the system and can ensure the uniformity of subsequent cross-linking. When the amount of organic ligands is excessive, there will be too much uncoordinated organic matter in the system. The excess organic ligands will be adsorbed on the surface of the Cr-MOF oligomers, hindering the hydroxyl bridging or oxygen bridging reaction of the unsaturated Cr (III) metal center, and it is impossible to obtain a cross-linked network structure. 3+ Excessive metal ions, excessive Cr in the system 3+ It reacts with -OH groups or H2O molecules in the solvent to form [Cr(H2O)5(OH)] 2+ 、[Cr(H2O)4OH)2] + Species such as Cr-MOF and Cr-MOF oligomers compete with each other for the cross-linking, interfering with the formation of the cross-linking network, thus preventing the aggregation of Cr-MOF oligomers.

[0012] Preferably, the reaction time of Cr-MOF gel is 1 h to 8 h; when the reaction time is less than 1 h, sufficient Cr-MOF oligomers cannot be obtained, and only a clear and transparent solution can be obtained in the end; when the reaction time is greater than 6 h, the gel network will be destroyed, and the continuous epitaxial growth caused by surface tension will induce oligomer nucleation and crystallization, causing the gel system to transform into a crystal.

[0013] Preferably, after aging, the obtained gel is subjected to solvent exchange to replace the residual solvent in the pores and prevent the pores from collapsing during drying.

[0014] Since the Cr-MOF gel is composed of a continuous three-dimensional Cr-MOF network structure and a solvent filling the gaps in the three-dimensional network structure, the Cr-MOF gel is immersed in an aniline solution. The aniline molecules diffuse through the solvent medium in the Cr-MOF gel, and the diffusion direction is from the high-concentration area outside the Cr-MOF gel to the low-concentration area inside the Cr-MOF gel. After a 12-hour immersion process, a Cr-MOF gel containing aniline molecules is obtained. The aniline molecules are present in the solvent molecules in the gaps between the three-dimensional network structure of the Cr-MOF gel. Preferably, the aniline solution is obtained by dissolving aniline in a first solvent, and the concentration of the aniline solution is 0.01 mol / L to 0.2 mol / L.

[0015] Preferably, the Cr-MOF gel is immersed in the aniline solution for 12 to 14 hours at room temperature.

[0016] Since polyaniline obtained by low-temperature polymerization is conductive, polyaniline obtained by high-temperature polymerization has poor or even no conductivity. Preferably, the polymerization reaction temperature is -10°C to 0°C, and the reaction time is 12h to 14h.

[0017] Under conditions of -10°C to 0°C, the Cr-MOF gel containing aniline molecules is immersed in an initiator solution to allow the initiator to diffuse into the three-dimensional network structure of the Cr-MOF gel, triggering a polymerization reaction. Polyaniline is generated in situ in the solvent medium in the three-dimensional network structure, and then cross-linking occurs to form a network structure, obtaining a Cr-MOF / polyaniline composite gel.

[0018] Preferably, the initiator solution is obtained by dissolving an initiator in a first solvent, the initiator is ammonium persulfate, and the concentration of the initiator solution is 0.01 mol / L to 0.1 mol / L.

[0019] In the Cr-MOF gel system, the continuous three-dimensional network structure of Cr-MOF and the solvent medium filling the gaps in the three-dimensional network structure are interpenetrating with each other. Therefore, in the synthesized Cr-MOF / polyaniline composite gel system, the polymer network of polyaniline and the three-dimensional network structure of Cr-MOF are interpenetrating with each other. This interpenetrating conductive network provides rich paths for the rapid transfer of charges, which is beneficial to improving the overall conductivity of the composite system.

[0020] Preferably, the first solvent is ethanol.

[0021] The second object of the present invention is to provide the Cr-MOF / polyaniline composite gel prepared by the above preparation method.

[0022] The third object of the present invention is to provide the use of the above-mentioned Cr-MOF / polyaniline composite gel in preparing an electrode material for a supercapacitor.

[0023] Compared with the prior art, the present invention has the following technical effects: 1. In the present invention, the chromium source and the organic ligand are placed at 80°C to 160°C in the first solvent system to react so that Cr 3+The method comprises the following steps: coordinating with an organic ligand to form a continuous three-dimensional network structure, and aging to obtain a Cr-MOF gel; soaking the Cr-MOF gel in an aniline solution to allow the aniline molecules to diffuse and penetrate into the gaps of the three-dimensional network structure; then soaking the Cr-MOF gel containing aniline molecules in an initiator solution to allow the initiator to diffuse into the three-dimensional network structure, triggering a polymerization reaction of aniline, generating polyaniline in situ, and cross-linking the polyaniline to form a composite network structure, thereby obtaining a Cr-MOF / polyaniline composite gel. The present invention utilizes colloidal Cr-MOF as an intermediate phase between solid and liquid, effectively overcoming the problem of poor interface contact inherent in traditional solid-state synthesis methods. Furthermore, the Cr-MOF gel is composed of a continuous three-dimensional network structure of Cr-MOF and a solvent filling the gaps in the three-dimensional network structure. The aniline solution is rapidly and evenly dispersed into the gaps in the three-dimensional network structure of the macroscopically continuous Cr-MOF gel by diffusion, and a polymerization reaction occurs under the action of an initiator to generate polyaniline in situ. This solves the technical problem of uneven distribution of polyaniline and pore clogging caused by the lack of MOF surface anchoring points for in-situ binding.

[0024] 2. The present invention synthesizes MIL-101-Cr gel via a simple hydrothermal process, eliminating the need for hydrofluoric acid etching. Because the liquid solvent uniformly penetrates the colloidal MOF matrix, the aniline solution can be rapidly and uniformly dispersed into the macroscopically continuous MOF phase via liquid-phase diffusion. This simple preparation method is suitable for industrial production.

[0025] 3. The polymer network of polyaniline and the three-dimensional network structure of Cr-MOF in the Cr-MOF / polyaniline composite gel prepared by the present invention are interpenetrating. This interpenetrating conductive network provides abundant paths for the rapid transfer of charges, which is beneficial to improving the overall ion transport efficiency and conductivity of the composite system.

[0026] 4. The Cr-MOF / polyaniline composite gel prepared by the present invention has a tight, uniform and dense structure, which is superior to the structure obtained by traditional ex situ physical blending technology. Moreover, the Cr-MOF / polyaniline composite gel has high specific capacitance and rate capability as an electrode material for supercapacitors. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the XRD pattern of the Cr-MOF / polyaniline composite gel prepared in Example 1.

[0028] Figure 2 This is the SEM image of the Cr-MOF / polyaniline composite gel prepared in Example 1.

[0029] Figure 3 The cyclic voltammetry curves of the Cr-MOF gel / polyaniline electrode prepared in Example 1 at different scanning speeds are shown.

[0030] Figure 4 The cyclic voltammetry curves of the Cr-MOF gel / polyaniline electrode prepared in Example 2 at different scanning speeds are shown.

[0031] Figure 5 This is the constant current charge-discharge curve of the Cr-MOF gel / polyaniline electrode prepared in Example 1.

[0032] Figure 6 This is the constant current charge-discharge curve of the Cr-MOF gel / polyaniline electrode prepared in Example 2. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below with reference to specific embodiments and accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0034] In the description of the present invention, unless otherwise specified, all reagents used are commercially available and all methods used are conventional techniques in the art.

[0035] The following is further described through specific examples.

[0036] Example 1 A method for preparing a Cr-MOF / polyaniline composite gel, comprising the following steps: Under stirring conditions, 3.630 g of cobalt nitrate nonahydrate was dissolved in 30 mL of ethanol to obtain a cobalt nitrate solution; 2.104 g of trimesic acid was dissolved in 30 mL of ethanol to obtain a trimesic acid solution; the cobalt nitrate solution and the trimesic acid solution were ultrasonically treated for 30 minutes to obtain a Cr-MOF precursor.

[0037] The Cr-MOF precursor was transferred to a hydrothermal reactor and reacted at 120 °C for 2 h to obtain a wet gel.

[0038] After the wet gel was aged at room temperature for 24 h, it was solvent exchanged with 80 mL of ethanol three times, each time for 12 h, to obtain the Cr-MOF gel.

[0039] Aniline was dissolved in ethanol to obtain a 0.07 mol / L aniline solution; ammonium persulfate was dissolved in ethanol to obtain a 0.03 mol / L ammonium persulfate solution.

[0040] The Cr-MOF gel was immersed in 60 mL of aniline solution for 12 h of solvent exchange, and then immersed in 60 mL of ammonium persulfate solution for in-situ polymerization at -5°C for 12 h to obtain a composite gel.

[0041] The composite gel was placed in an oven and dried at 80° C. to obtain a Cr-MOF / polyaniline composite gel.

[0042] Example 2 A method for preparing a Cr-MOF / polyaniline composite gel, comprising the following steps: Under stirring conditions, 3.630 g of chromium nitrate nonahydrate was dissolved in 30 mL of ethanol to obtain a chromium nitrate solution; 2.104 g of trimesic acid was dissolved in 30 mL of ethanol to obtain a trimesic acid solution; the chromium nitrate solution and the trimesic acid solution were ultrasonically treated for 30 minutes to obtain a Cr-MOF precursor.

[0043] The Cr-MOF precursor was transferred to a hydrothermal reactor and reacted at 80 °C for 4 h to obtain a wet gel.

[0044] After the wet gel was aged at room temperature for 24 h, it was solvent exchanged with 200 mL of ethanol three times, each time for 24 h, to obtain the Cr-MOF gel.

[0045] Aniline was dissolved in ethanol to obtain a 0.1 mol / L aniline solution; ammonium persulfate was dissolved in ethanol to obtain a 0.1 mol / L ammonium persulfate solution.

[0046] The Cr-MOF gel was immersed in 60 mL of aniline solution for 12 h of solvent exchange, and then immersed in 60 mL of ammonium persulfate solution for in situ polymerization under refrigeration conditions for 4 h to obtain a composite gel.

[0047] The composite gel was placed in an oven and dried at 80° C. to obtain a Cr-MOF / polyaniline composite gel.

[0048] Example 3 A method for preparing a Cr-MOF / polyaniline composite gel, comprising the following steps: Under stirring conditions, 1.815 g of cobalt nitrate nonahydrate was dissolved in 30 mL of ethanol to obtain a cobalt nitrate solution; 2.104 g of trimesic acid was dissolved in 30 mL of ethanol to obtain a trimesic acid solution; the cobalt nitrate solution and the trimesic acid solution were ultrasonically treated for 30 minutes to obtain a Cr-MOF precursor.

[0049] The Cr-MOF precursor was transferred to a hydrothermal reactor and reacted at 160 °C for 1 h to obtain a wet gel.

[0050] After the wet gel was aged at room temperature for 24 h, it was solvent exchanged with 80 mL of ethanol three times, each time for 12 h, to obtain the Cr-MOF gel.

[0051] Aniline was dissolved in ethanol to obtain a 0.07 mol / L aniline solution; ammonium persulfate was dissolved in ethanol to obtain a 0.03 mol / L ammonium persulfate solution.

[0052] The Cr-MOF gel was immersed in 60 mL of aniline solution for 12 h of solvent exchange, and then immersed in 60 mL of ammonium persulfate solution for in-situ polymerization at -5°C for 12 h to obtain a composite gel.

[0053] The composite gel was placed in an oven and dried at 80° C. to obtain a Cr-MOF / polyaniline composite gel.

[0054] Example 4 A method for preparing a Cr-MOF / polyaniline composite gel, comprising the following steps: Under stirring conditions, 1.815 g of cobalt nitrate nonahydrate was dissolved in 30 mL of ethanol to obtain a cobalt nitrate solution; 4.208 g of trimesic acid was dissolved in 30 mL of ethanol to obtain a trimesic acid solution; the cobalt nitrate solution and the trimesic acid solution were ultrasonically treated for 30 minutes to obtain a Cr-MOF precursor.

[0055] The Cr-MOF precursor was transferred to a hydrothermal reactor and reacted at 80 °C for 6 h to obtain a wet gel.

[0056] After the wet gel was aged at room temperature for 24 h, it was solvent exchanged with 80 mL of ethanol three times, each time for 12 h, to obtain the Cr-MOF gel.

[0057] Aniline was dissolved in ethanol to obtain a 0.07 mol / L aniline solution; ammonium persulfate was dissolved in ethanol to obtain a 0.03 mol / L ammonium persulfate solution.

[0058] The Cr-MOF gel was immersed in 60 mL of aniline solution for 12 h of solvent exchange, and then immersed in 60 mL of ammonium persulfate solution for in-situ polymerization at -5°C for 12 h to obtain a composite gel.

[0059] The composite gel was placed in an oven and dried at 80° C. to obtain a Cr-MOF / polyaniline composite gel.

[0060] Comparative Example 1 A preparation method of a Cr-MOF / polyaniline composite material, the specific steps are as follows: Under stirring conditions, 3.630 g of cobalt nitrate nonahydrate was dissolved in 30 mL of ethanol to obtain a cobalt nitrate solution; 2.104 g of trimesic acid was dissolved in 30 mL of ethanol to obtain a trimesic acid solution; the cobalt nitrate solution and the trimesic acid solution were ultrasonically treated for 30 minutes to obtain a Cr-MOF precursor.

[0061] The Cr-MOF precursor was transferred to a hydrothermal reactor and reacted at 200°C for 48 hours. After the reaction, it was filtered and then dried at 80°C to obtain the Cr-MOF material.

[0062] Aniline was dissolved in ethanol to obtain a 0.1 mol / L aniline solution; ammonium persulfate was dissolved in ethanol to obtain a 0.1 mol / L ammonium persulfate solution.

[0063] The Cr-MOF material was immersed in 200 mL of aniline solution for 12 hours of solvent exchange, and then immersed in 60 mL of ammonium persulfate solution for in-situ polymerization at -5°C for 4 hours. After the reaction was completed, it was filtered and then dried at 80°C to obtain a Cr-MOF / polyaniline composite material.

[0064] The difference from Example 1 is: The reaction temperature of the Cr-MOF precursor in the hydrothermal reactor was 200°C and the reaction time was 48 h.

[0065] Application Example 1 A method for preparing a Cr-MOF / polyaniline electrode material comprises the following steps: The Cr-MOF / polyaniline composite gel prepared in Example 1, conductive carbon black, and polytetrafluoroethylene were mixed at a mass ratio of 8:1:1 to obtain an active slurry.

[0066] The slurry was coated on the surface of nickel foam using a scraper and dried in a vacuum drying oven at 80° C. for 24 h to obtain a Cr-MOF gel / polyaniline electrode material.

[0067] Application Example 2 A method for preparing a Cr-MOF / polyaniline electrode material comprises the following steps: The Cr-MOF / polyaniline composite gel prepared in Example 2, conductive carbon black, and polytetrafluoroethylene were mixed at a mass ratio of 8:1:1 to obtain an active slurry.

[0068] The slurry was coated on the surface of nickel foam using a scraper and dried in a vacuum drying oven at 80° C. for 24 h to obtain a Cr-MOF / polyaniline electrode material.

[0069] Comparative Application Example 1 A method for preparing a Cr-MOF / polyaniline electrode material comprises the following steps: The Cr-MOF / polyaniline composite material prepared in Comparative Example 1, conductive carbon black and polytetrafluoroethylene were mixed in a mass ratio of 8:1:1 to obtain an active slurry.

[0070] The slurry was coated on the surface of nickel foam using a scraper and dried in a vacuum drying oven at 80° C. for 24 h to obtain a Cr-MOF / polyaniline electrode material.

[0071] Examples 1 to 4 of the present invention all prepared Cr-MOF / polyaniline composite gels that solve the problems of poor interface contact and low charge transfer efficiency caused by non-in-situ physical mixing and the lack of MOFs surface anchoring sites by in-situ binding, and the crystal structure data of the Cr-MOF / polyaniline composite gels prepared in Examples 2 to 4 are similar to those in Example 1. The present invention takes Example 1 and Comparative Example 1 as examples below, and the specific research methods and results are as follows: Experimental test: 1. XRD test: like Figure 1 As shown in the figure, the overall profile of the XRD diffraction pattern of the Cr-MOF / polyaniline composite gel prepared in Example 1 is consistent with the standard curve of crystalline MIL-101-Cr (CCDC 648835), confirming the presence of MOFs structure in the hybrid material. Compared with the diffraction pattern of the standard curve, all diffraction peaks of the MOF gel / polyaniline composite material prepared in Example 1 show broadening, which indicates that the crystallinity of the composite material formed by the composite of Cr-MOF gel and polyaniline is reduced. In addition, there are two broad peaks at 20.6° and 25.7°, corresponding to the (100) and (110) planes of polyaniline, indicating the successful composite of polyaniline and Cr-MOF gel.

[0072] 2. SEM test: like Figure 2 As shown, the Cr-MOF / polyaniline composite gel prepared in Example 1 exhibits a tightly packed and dense structure composed of nanoparticles, and no isolated polyaniline is observed, indicating that the polyaniline is uniformly dispersed in the Cr-MOF gel matrix without affecting the compact structure of the matrix.

[0073] 3. Electrical performance test: The Cr-MOF / polyaniline electrode materials prepared in Application Examples 1 to 2 and Comparative Example 1 are hereinafter referred to as electrode materials; the electrode materials are used as working electrodes, the Pt electrode is used as the counter electrode, the saturated calomel electrode is used as the reference electrode, and a 1 mol / L Li2SO4 solution is used as the electrolyte to form a three-electrode system, and electrochemical tests are performed, wherein the cyclic voltammetry test potential range is 0 V to 0.8 V, and the electrochemical impedance spectroscopy test frequency range is 0.1 Hz to 100 kHz.

[0074] like Figure 3 As shown, the Cr-MOF / polyaniline electrode prepared in Example 1 exhibited a nearly rectangular cyclic voltammetry curve at different scanning speeds, without obvious redox peaks, and was a typical double-layer capacitor.

[0075] like Figure 4 As shown, the cyclic voltammetry curve of the Cr-MOF / polyaniline electrode prepared in Example 2 shows a nearly rectangular cyclic voltammetry curve without obvious redox peaks, which is a typical double-layer capacitor.

[0076] like Figure 5 As shown, all constant current charge-discharge curves of the Cr-MOF / polyaniline electrode prepared in Example 1 at current densities of 1A / g to 20A / g have good symmetry and near-linear characteristics, showing good capacitance characteristics. Calculated according to the specific capacitance calculation formula:

[0077] ; in, is the specific capacitance, unit is F / g; I is the discharge current in A, Δt is the discharge time in s, m is the mass of the active material in g; ∆V is the voltage window of the charge and discharge test in V.

[0078] The specific capacitance of the Cr-MOF / polyaniline electrode prepared in Application Example 1 is 423.8 F / g at a current density of 1 A / g. At a current density of 20 A / g, the specific capacitance is still 240.0 F / g.

[0079] like Figure 6 As shown, all constant current charge-discharge curves of the Cr-MOF / polyaniline electrode prepared in Example 2 at current densities of 1A / g to 20A / g have good symmetry and near-linear characteristics, showing good capacitive characteristics. According to the calculation formula of specific capacitance, the specific capacitance of the prepared Cr-MOF / polyaniline electrode at 1A / g is 411.3F / g. At a current density of 20A / g, its specific capacitance is still 187.5F / g.

[0080] Table 1 Electrical properties of electrode materials prepared in Application Example 1 to Application Example 2 and Application Comparative Example 1 As shown in Table 1, the specific capacitance of the Cr-MOF / polyaniline electrode prepared in Example 1 at a current density of 1A / g is 423.8F / g, and at a current density of 20A / g, its specific capacitance is still 240.0F / g. The specific capacitance of the Cr-MOF / polyaniline electrode prepared in Example 2 at a current density of 1A / g is 411.3F / g, and at a current density of 20A / g, its specific capacitance is still 187.5F / g. The specific capacitance of the Cr-MOF / polyaniline electrode prepared in Comparative Example 1 at 1A / g is 182.7F / g, and at a current density of 20A / g, its specific capacitance is 61.0F / g. This is because no Cr-MOF gel is formed in Comparative Example 1, and the Cr-MOF gel is not formed due to the high reaction temperature. 3+ The overly vigorous coordination reaction between the ions and trimesic acid leads to excessive and rapid growth of Cr-MOF nuclei, which ultimately aggregate and form precipitates. Alternatively, prolonged reaction time may disrupt the gel network, causing continued epitaxial growth caused by surface tension to induce oligomer nucleation and crystallization, transforming the gel system into a crystalline structure. When Cr-MOF materials are mixed with polymers, poor interfacial contact results, resulting in low charge transfer efficiency when the Cr-MOF / polyaniline composite is used as an electrode.

[0081] It should be noted that when numerical ranges are mentioned in the present invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints may be selected. Since the steps and methods used are the same as those in the embodiments, the present invention describes preferred embodiments to avoid redundancy. Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they understand the basic inventive concepts, and such changes and modifications fall within the scope of the present invention.

[0082] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. If these modifications and variations of the present invention fall within the scope of the equivalent technology of the present invention, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a Cr-MOF / polyaniline composite gel, characterized in that: The following steps are involved: In the first solvent system, the chromium source and the organic ligand are placed at 80℃~160℃ to react so that Cr 3+ Coordinate with organic ligands to form a continuous three-dimensional network structure, and after aging, Cr-MOF gel is obtained; The Cr-MOF gel is immersed in an aniline solution to allow the aniline molecules to diffuse and penetrate into the gaps of the three-dimensional network structure. Then, the Cr-MOF gel containing aniline molecules is immersed in an initiator solution to allow the initiator to diffuse into the three-dimensional network structure, triggering the polymerization reaction of aniline and generating polyaniline in situ to obtain a Cr-MOF / polyaniline composite gel; the molar ratio of the chromium source to the organic ligand is 3:1 to 6.

2. The method for preparing the Cr-MOF / polyaniline composite gel according to claim 1, wherein: The organic ligand is trimesic acid.

3. The method for preparing the Cr-MOF / polyaniline composite gel according to claim 1, wherein: The reaction time for preparing Cr-MOF gel is 1 h to 8 h.

4. The method for preparing the Cr-MOF / polyaniline composite gel according to claim 1, wherein: The Cr-MOF gel was immersed in the aniline solution for 12 to 14 hours at room temperature.

5. The method for preparing the Cr-MOF / polyaniline composite gel according to claim 1, wherein: The polymerization reaction temperature is -10°C to 0°C, and the time is 12h to 14h.

6. The method for preparing the Cr-MOF / polyaniline composite gel according to claim 1, wherein: The aniline solution is obtained by dissolving aniline in a first solvent. The concentration of the aniline solution is 0.01 mol / L to 0.2 mol / L. The first solvent is ethanol.

7. The method for preparing the Cr-MOF / polyaniline composite gel according to claim 1, wherein: The initiator solution is obtained by dissolving an initiator in a first solvent, the initiator is ammonium persulfate, and the concentration of the initiator solution is 0.01 mol / L to 0.1 mol / L.

8. The method for preparing the Cr-MOF / polyaniline composite gel according to claim 1, wherein: The chromium source was chromium nitrate hexahydrate.

9. A Cr-MOF / polyaniline composite gel, characterized in that: The Cr-MOF / polyaniline composite gel is prepared by the preparation method of the Cr-MOF / polyaniline composite gel according to any one of claims 1 to 8.

10. Use of the Cr-MOF / polyaniline composite gel according to claim 9 in preparing an electrode material for a supercapacitor.

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