A method for preparing a methyl-modified polyaniline and construction of a supercapacitor having excellent cycle stability
By introducing methyl functional groups and hydrogen-bonded binders into aniline derivatives, the structural damage problem of polyaniline-based supercapacitors during charge-discharge cycles was solved, improving their cycle stability and capacity, and achieving a highly efficient self-healing effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEFEI UNIV OF TECH
- Filing Date
- 2024-12-23
- Publication Date
- 2026-06-02
AI Technical Summary
Polyaniline-based supercapacitors suffer structural damage due to volume expansion during charge-discharge cycles, resulting in poor cycle stability. Existing self-healing methods are subject to stringent conditions and have limited effectiveness.
By introducing methyl functional groups into aniline derivatives to regulate the flexibility of the molecular chain and combining them with hydrogen bonding binders, an electrode material combining methyl-modified polyaniline and hydrogen bonding binders was prepared, which repaired electrode structural damage and improved cycle stability.
It achieves increased capacity and extended electrochemical cycle life of polyaniline-based supercapacitors. The materials are readily available, environmentally friendly, and easy to operate, making them suitable for a variety of applications.
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Figure CN119708473B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrochemical energy storage, specifically relating to a method for preparing methyl-modified polyaniline and the construction of a supercapacitor with excellent cycle stability. Background Technology
[0002] With the continuous advancement of modern technology, the increasingly prominent issues of energy consumption and shortage have gradually become a social hotspot. Over the past few decades, the use of fuel cells, chemical batteries, and capacitors has alleviated energy consumption pressure to some extent. However, drawbacks such as high production costs, limited equipment lifespan, and environmental unfriendliness have consistently limited the further development of the energy industry. Supercapacitors, as an energy storage device positioned between secondary batteries and traditional capacitors, possess significant advantages in rate performance, charge / discharge rate, cycle life, and operating costs, thus becoming a highly promising energy storage device in the development of new energy sources.
[0003] PANI boasts advantages such as high theoretical specific capacity, good stability, environmental friendliness, and low cost, finding applications in electrochemistry, electrochromism, and anti-corrosion coatings. However, during electrochemical charge-discharge cycling, the conjugated rigid structure of PANI undergoes volume expansion / contraction due to ion insertion / extraction, leading to material pulverization and electrode structure damage. Consequently, some electrode material cannot participate in electron contact, resulting in PANI capacity decay and poor cycle stability. Introducing functional groups into the benzene ring of the PANI molecular chain is one method to adjust the interchain spacing and benzene ring conjugation effect. The methyl group, as a weakly electron-donating group, appropriately reduces the benzene ring conjugation effect while maintaining electrochemical activity, making the molecular chain more flexible and adjusting the PANI morphology, thus achieving a higher specific capacity. The self-healing process can be designed by adding functional guest materials inside or on top of the polymer matrix in the composite system. Bond recombination can occur between two polymer chains, between two or more different polymers, or between polymer chains and other guest small molecules or nanomaterials. Therefore, to achieve the restoration of its electrode structure and recover its capacity, designing a widely applicable self-healing electrode material becomes essential. According to the self-healing mechanism, the formation kinetics of dynamic covalent bonds, such as Diels-Alder reactions, disulfide bonds, and imine bonds, are slow and often require external stimuli, such as heating or pH response, to trigger the healing process, making practical applications quite demanding. In contrast, non-dynamic covalent bonds, primarily hydrogen bonds, can achieve a dynamic self-healing process at room temperature. Their supramolecular self-assembly dynamics and polymer chain fluidity can significantly shorten the healing process. Against this backdrop, the use of methyl-modified polyaniline and hydrogen-bonded binders can be practically applied to improve the performance of polyaniline-based supercapacitors and is expected to meet the needs of many practical applications. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing methyl-modified polyaniline (PANI) and the construction of a supercapacitor with excellent cycle stability. Based on the structural damage caused by the volume expansion of PANI during charge-discharge cycles, this invention adjusts the flexibility and interchain spacing of the polymer chains through copolymerization of aniline derivatives. Combining this with the traction effect of hydrogen bonds on the electrode material, a hydrogen-bonding binder containing a large number of hydrogen bonds is introduced. This combination of methyl modification and the hydrogen-bonding binder promotes the stability of the electrode structure, providing a simple and effective method for improving the capacity and electrochemical cycle life of polyaniline-based supercapacitors.
[0005] This invention introduces methyl functional groups onto the benzene ring by copolymerizing N-phenyl-p-phenylenediamine (AD) with m-methylaniline (mT), thereby weakening the intermolecular forces of the polymer and controlling the morphology of polyaniline. Specifically, this invention controls the morphology of polyaniline by introducing methyl functional groups into the benzene ring via aniline dimer, improving its capacity and further combining it with self-healing materials. The abundant hydrogen bonds in the amide bonds repair structural damage to polyaniline during cycling, stabilizing the electrode structure and enhancing the cycling stability and capacity of the polyaniline-based supercapacitor.
[0006] The method for preparing methyl-modified polyaniline of the present invention includes the following steps:
[0007] Step 1: Weigh 100-500 mg of N-phenyl-p-phenylenediamine (AD), add it to a mixed solution of 5-20 mL of ethanol and 10-30 mL of 1 M HCl, stir well, and sonicate for 10-30 min. This solution is called solution A.
[0008] Step 2: Weigh 100-500 mg of m-methylaniline (mT), add 10-50 mL of 1 M HCl, stir well, and sonicate for 10-30 min. This solution is labeled as solution B.
[0009] Step 3: Weigh 300-1500 mg APS, add 20-80 mL of 1 M HCl and stir well. Place at 0-5℃ for 10-50 min and record as solution C.
[0010] Step 4: Pour the solution B obtained in Step 2 into the solution A obtained in Step 1, sonicate at 0-5℃ for 10-30 min, and then stir at 0-5℃ for 10-40 min.
[0011] Step 5: Slowly add solution C obtained in step 3 to the system in step 4 while stirring. The dropping rate is 1-5 seconds per drop. Maintain the dropping process for 0.5-2 hours and continue stirring the reaction at 0-5°C for 4-12 hours.
[0012] Step 6: The reaction solution obtained in Step 5 is centrifuged and washed with a mixture of deionized water and ethanol to remove residual acid and organic matter. The product is then freeze-dried and collected to obtain methyl-modified polyaniline, denoted as PACM.
[0013] This invention also provides a method for constructing a supercapacitor with excellent cycle stability. The method involves preparing an electrode slurry using PACM or PANI as the active material, SIR as a hydrogen bonding binder, conductive carbon black (SP) as a conductive agent, and polybenzimidazole (PBI) as a binder, with N-methylpyrrolidone (NMP) as a solvent. The slurry is then coated with graphite paper as the current collector to prepare the electrode. Simultaneously, PBI is used as the separator, and H3PO4 is used as the electrolyte. Two electrode sheets with the active material coated on one side facing each other are stacked together with the separator in a sandwich structure. The side loaded with the active material is then bonded to the middle PBI membrane, assembling a symmetrical device.
[0014] In the preparation of symmetric device slurries, the mass ratio of PACM or PANI, SIR, SP to PBI is (70%-97%):(1%-15%):(1%-15%):(1%-10%). Using graphite paper (GP) as the current collector, the slurry coating area is >1 cm². 2 .
[0015] The concentration of the electrolyte is 1M-6M.
[0016] The loading mass of the active material on a single electrode is 0.1-5 mg / cm³. 2 The loading mass of the active material in the device is 0.2-10 mg / cm³. 2 .
[0017] The method for synthesizing the active substance PANI is as follows:
[0018] A certain amount of aniline (An) monomer was uniformly dispersed in 1M HCl solution; this is solution I. A certain amount of ammonium persulfate (APS) was ultrasonically dispersed in an equal volume of 1M hydrochloric acid solution; this is labeled solution II. Solution II was slowly added dropwise to solution I under ice bath conditions, with magnetic stirring. The addition time was 30 min, and the reaction time was 4-8 h. The mixture was centrifuged and washed 3-4 times with deionized water and ethanol until the centrifuged liquid was neutral. The product was collected. The molar ratio of aniline (An) monomer to ammonium persulfate (APS) was 1:1.
[0019] The synthesis method of the hydrogen-bonded binder SIR is as follows:
[0020] (1) Take 100-500 mL of isophorone diisocyanate (IPDI) into a three-necked flask, add 1-10 mL of dimethylformamide (DMF), stir well, and label it as solution X;
[0021] (2) Weigh 0.2-5g of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (Pluronic P123), add 0.1-10mg of dibutyltin dilaurate (DBTDL) and 1-20mL of dimethylformamide (DMF), stir well, and record it as solution Y;
[0022] (3) Weigh 100-700 mg of imidazolidinyl urea (IU), add 1-20 mL of dimethylformamide (DMF) and stir well, and label it as solution Z;
[0023] (4) Pour solution Y into solution X, place the three-necked flask in an oil bath and stir magnetically, then heat at 60-100℃ for 4-8 hours; after heating, add solution Z to the three-necked flask and continue to heat and stir slowly for 8-16 hours.
[0024] (5) After the reaction is complete, add 50-300 mL of isopropyl ether (IPE) to the product to produce a precipitate. Centrifuge to collect the precipitate. Repeat this precipitation-centrifugation operation twice. Place the collected precipitate in a vacuum drying oven at 60℃ and dry for 12-24 h. Add 5-30 mL of NMP to dissolve the precipitate and prepare a 10-50 wt% SIR solution. Since the electrode paste uses NMP as a solvent, and SIR is soluble in NMP, it is more convenient for electrode fabrication.
[0025] Preparation method of PBI solution: Weigh 1-5g of PBI powder, add it to 20-100mL of dimethylacetamide (DMAC) solution, heat and stir at 120℃ for 4-6h, remove and cool to obtain 1-10wt% PBI solution.
[0026] Preparation method of PBI membrane: Take a PBI solution with a mass concentration of 1-10wt% (typical value is 5wt%) and spread it evenly on a flat glass plate. Slowly shake to level the liquid and dry it at 60℃ for 8-12h to obtain a PBI membrane with a thickness of 10-30μm.
[0027] Three-electrode tests were performed on PACM electrodes synthesized with different monomer mass ratios, and electrochemical performance tests were conducted on symmetric devices with different amounts of SIR addition.
[0028] The electrochemical performance of this invention was tested under pressures of 0.01-5 MPa.
[0029] The beneficial effects of this invention are reflected in:
[0030] 1. The raw materials used are readily available, low in cost, environmentally friendly, and have low requirements for instruments and are easy to operate.
[0031] 2. This invention regulates the intermolecular forces of polyaniline by substituting meta-methyl groups on the benzene ring, thereby improving the morphology of polyaniline, increasing the specific capacity of the material, improving the electrochemical performance of polyaniline, and also providing a solution for regulating the performance of polyaniline in monomer copolymerization.
[0032] 3. This invention utilizes a relatively simple method to introduce a hydrogen-bonded binder into a supercapacitor device, thereby preparing a self-healing polyaniline supercapacitor to maintain electronic contact between the electrodes during cycling.
[0033] 4. This invention uses aniline derivative copolymer electrode materials and hydrogen-bonded binders to prepare polyaniline-based supercapacitors with excellent cycle performance, effectively solving the problem of poor cycle performance faced by current polyaniline-based supercapacitor devices, and providing a solution for improving the cycle life of other conductive polymer devices. Attached Figure Description
[0034] Figure 1 These are Fourier transform infrared (FTIR) spectra of the PANI, PACM, and PACM-SIR electrode materials.
[0035] Figure 2 These are SEM images of PACM(a), AT(b), PMT(c), and PANI(d) materials.
[0036] Figure 3 The charts show a comparison of the three-electrode performance of PACM, AT, PMT, and PANI, as well as a comparison of the electrochemical performance of the electrode materials in the three-electrode system. (a) Comparison of CV curves at a scan rate of 50 mV / s; (b) Comparison of CD curves at a current density of 1 A / g; (c) Comparison of specific capacity at different current densities.
[0037] Figure 4 The following are electrochemical performance graphs of the PACM electrode in a three-electrode system: (a) CV curve; (b) CD curve; (c) specific capacity at different current densities.
[0038] Figure 5 The following are electrochemical performance graphs of PACM-SIR symmetric devices: (a) CV curve; (b) CD curve; (c) specific capacity at different current densities; (d) performance graph after 30,000 cycles at a current density of 5 A / g.
[0039] Figure 6 These are SEM images of the electrode surfaces of the PACM-SIR symmetric device before cycling (a, b), after 5000 cycles (c, d), and after 30000 cycles (e, f).
[0040] Figure 7The following are electrochemical performance graphs for four symmetric devices with PANI:SIR:SP:PBI ratios of 70:10:10:10, 70:15:10:5, 70:20:5:5, and 70:15:15:PANI:SIR:SP:PBI: (a) Comparison of CV curves at a scan rate of 50 mV / s; (b) Comparison of CD curves at a current density of 1 A / g; (c) Comparison of specific capacity at different current densities; (d) Comparison of cycling performance after 10,000 cycles at a current density of 5 A / g.
[0041] Figure 8 These are SEM images of PACM-1(a) and PACM-2(b).
[0042] Figure 9 The graphs show a comparison of the three-electrode performance of PACM, PACM-1, and PACM-2, and a comparison of the electrochemical performance of the electrode materials in the three-electrode system; (a) a comparison of CV curves at a scan rate of 50 mV / s; (b) a comparison of CD curves at a current density of 1 A / g; and (c) a comparison of specific capacity at different current densities.
[0043] Figure 10 The following are electrochemical performance graphs of the PACM symmetric device: (a) CV curve; (b) CD curve; (c) specific capacity compared with the PACM-SIR symmetric device at different current densities; (d) performance graph compared with the PACM-SIR symmetric device after 30,000 cycles at a current density of 5 A / g.
[0044] Figure 11 SEM images of the electrode surfaces of a PACM symmetric device before (a, b) and after (c, d) cycling. Detailed Implementation
[0045] The following examples illustrate specific implementation schemes related to the present invention. These are merely limited examples used to illustrate the implementation schemes of the present invention and do not limit the scope of the present invention.
[0046] Example 1:
[0047] 1. Preparation of PACM
[0048] Weigh 170 mg AD and ultrasonically disperse it in a mixed solution of 10 mL ethanol and 10 mL 1 M HCl, labeling it solution A; weigh 170 mg mT and ultrasonically disperse it in 15 mL 1 M HCl solution, labeling it solution B; weigh 573 mg APS and dissolve it in 20 mL 1 M HCl solution, then ultrasonically disperse it, labeling it solution C; add solution B to solution A and stir for 30 min in an ice bath at 0-5℃, then gradually add solution C dropwise with stirring, continuing the reaction for 4-8 h. Collect the resulting product, wash it 3-4 times with ethanol and deionized water, and collect the product. Simultaneously, prepare materials with AD to mT mass ratios of 1:0, 2:1, 1:2, and 0:1, respectively, denoted as AT, PACM-1, PACM-2, and PMT.
[0049] 2. Preparation of PANI
[0050] Weigh 340 mg of aniline (An) monomer, add 30 mL of 1 M HCl solution and sonicate for 20 min, labeling this solution A. Weigh 833 mg of ammonium persulfate (APS), dissolve it in 20 mL of 1 M HCl solution, labeling this solution B. Cool solutions A and B in an ice bath at 0-5℃ for 30 min. Under stirring, add solution B dropwise to solution A at a rate of one drop every two seconds. The entire reaction process lasts for 4 h. Afterward, wash the collected solution 3-4 times by centrifugation with a mixture of deionized water and ethanol, and collect the precipitate.
[0051] 3. Preparation of hydrogen-bonded binders (SIR)
[0052] First, measure 365 mL of isophorone diisocyanate (IPDI) into a three-necked flask, then add 2.5 mL of dimethylformamide (DMF) and stir until homogeneous. This solution is labeled as solution X. Weigh 1.45 g of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (Pluronic P123), add 5.5 mg of dibutyltin dilaurate (DBTDL) and 10 mL of dimethylformamide (DMF), and stir until homogeneous. This solution is labeled as solution Y. Weigh 390 mg of imidazolidinyl urea (IU), add 10 mL of dimethylformamide (DMF), and stir until homogeneous. This solution is labeled as solution Z. Pour solution Y into solution X, place the three-necked flask in an oil bath, stir magnetically, and then heat for 4 hours. After heating, add solution Z to the three-necked flask and continue to heat and stir slowly for 12 hours. After the reaction was complete, 130 mL of isopropyl ether was added to the product to produce a precipitate. The precipitate was collected by centrifugation, and this precipitation-centrifugation operation was repeated twice. The collected precipitate was dried in a vacuum drying oven for 24 h to obtain the SIR polymer. 5 mL of NMP solution was added to dissolve the precipitate to form an approximately 50 wt% SIR solution.
[0053] 4. Electrochemical performance testing of the three-electrode system
[0054] The PACM, PANI, and SIR materials obtained in this embodiment are used as electrode materials for supercapacitors as follows: A portion of the collected PANI and PACM centrifuged liquid is coated onto graphite paper (1×2cm). 2 The electrode was dried on an 80℃ heating stage for 2 hours to serve as the working electrode, and its electrochemical performance was tested in a three-electrode system. PANI and PACM were used as active materials, SIR as a hydrogen bonding binder, SP as a conductive agent, and PBI as a binder, with a mass ratio of 70:15:10:5. NMP was used as the solvent to prepare the electrode slurry. The slurry was stirred for more than 14 hours and then coated onto graphite paper (1×2 cm). 2 The electrode was dried on a heating platform for 10 hours and used as the working electrode.
[0055] 5. Preparation of PBI membrane
[0056] The PBI membrane is prepared by spreading 5 mL of PBI solution evenly on a flat glass plate, slowly shaking it to level the liquid, and drying it at 60℃ for 8-12 h to obtain a PBI membrane with a thickness of 20 μm.
[0057] 6. Fabrication of Symmetrical Supercapacitors
[0058] Specifically, PACM was used as the active material, SIR as the hydrogen bonding binder, SP as the conductive agent, and PBI as the binder, with a mass ratio of 70:15:10:5. Electrodes were fabricated using N-methylpyrrolidone (NMP) solvent, and a PBI membrane was used as the separator. 6MH3PO4 was used as the electrolyte. Two electrodes with equal active material loadings and a separator were stacked together in a sandwich structure, with the PBI membrane sandwiched between the active material surfaces of the two electrodes, assembling a symmetrical device. Electrochemical tests were performed on the symmetrical supercapacitor device.
[0059] Figure 1 As can be seen, 1580cm -1 and 1492cm -1 The peak at 810 cm⁻¹ is attributed to the vibrations of the quinone and benzene rings, indicating the formation of PANI in the oxidized state of emerald salt, and that the vibrational intensity of the quinone ring is lower than that of the benzene ring. -1 1153cm -1 The peak at 1310 cm⁻¹ can be attributed to out-of-plane bending vibration of CH. -1 The peak CN tensile vibration at 3445cm -1 This corresponds to the OH vibration peak. Compared to pure PANI, the PACM copolymer peaks show a blue shift; for example, the corresponding C=C stretching vibration peak shifts from 1492 cm⁻¹. -1 Offset to 1472cm -1The blue shift indicates that the conjugated structure of PACM has weakened at 750 cm⁻¹. -1 The small absorption peak corresponds to the bending vibration of C-CH3 at the meta position of the benzene ring, at 1698 cm⁻¹. -1 and 1664 cm -1 The absorption peaks at the point are due to the C=O and -CONH- vibrations, proving that carbonyl and amide groups in SIR are introduced into the electrode material.
[0060] Figure 2 SEM images of PACM, AT, PMT and PANI materials. Figure 2 (a) It can be seen that PACM exhibits a loose and porous cross-linked network structure. Figure 2 (b) AT exhibits a dense polymer surface. Figure 2 In (c), the PMTs are dispersed and aggregated. Figure 2 (d) shows the clustered coral-like structure exhibited by PANI.
[0061] Figure 3 A comparison of the electrochemical performance of PACM, AT, PMT, and PANI electrode materials in a three-electrode system. Figure 3 (a) The CV curve can be obtained at a scan rate of 50 mV / s. PACM shows a larger curve closure area and a lower potential redox peak. Figure 3 (b) and Figure 3 (c) PACM combines the advantages of AT and PMT, exhibiting excellent rate performance and significantly improved specific capacitance.
[0062] Figure 4 This shows the electrochemical testing results of the PACM electrode material in a three-electrode system. Figure 4 (a) The CV curves show that the material has excellent pseudocapacitive properties and a highly reversible response. Figure 4 The CD image in (b) shows a symmetrical charge-discharge curve and no obvious voltage drop, indicating that the electrode material has good conductivity. Figure 4 (c) The specific capacity of the electrode material calculated from the CD curve is 850 F / g, 798 F / g, 760 F / g, 731 F / g, and 717 F / g at current densities of 1 A / g, 2 A / g, 5 A / g, 10 A / g, and 20 A / g, respectively. At a current density of 20 A / g, the capacity retention is 84.3%, indicating good rate performance.
[0063] Figure 5 The graph shows the electrochemical performance of the PACM-SIR symmetric device. Figure 5 (a) The CV curves show that no obvious deformation was observed at different scan rates, indicating that the material has excellent pseudocapacitive properties and reversible redox reaction. Figure 5 (b) The CD curve shows a charge-discharge plateau corresponding to the redox peak of the CV curve, and there is no obvious voltage drop. It has a specific capacitance of 158.7 F / g at a current density of 1 A / g, indicating that the electrode material has a better specific capacitance and better conductivity. Figure 5 (c) It exhibits excellent rate performance at different current densities; Figure 5 (d) shows that the addition of SIR gives the active material excellent cycling performance, retaining 84.3% capacity after 30,000 cycles at a current density of 5 A / g.
[0064] Figure 6 The images show SEM images of the PACM-SIR symmetric device before and after 30,000 cycles. It is clearly visible that as the number of cycles increases, the cracks on the electrode surface gradually close and eventually disappear, thus confirming the repair effect of SIR on the electrode surface and maintaining the electronic contact between the active material and the electrode sheet. Consequently, it still has a high capacity retention rate after 30,000 charge-discharge cycles.
[0065] Example 2:
[0066] 1. Preparation of hydrogen-bonded binders (SIR)
[0067] Same as Example 1.
[0068] 2. Preparation of PANI
[0069] Same as Example 1.
[0070] 3. Fabrication of symmetric supercapacitors with hydrogen-bonded binders
[0071] Using PANI as the active material, SIR as the hydrogen bonding binder, SP as the conductive agent, and PBI as the binder, matte devices were fabricated in mass ratios of 70:10:10:10, 70:15:10:5, and 70:20:5:5, respectively. Electrodes were fabricated using N-methylpyrrolidone (NMP) solvent, and a PBI membrane was used as the separator. 6M H3PO4 was used as the electrolyte. Two electrodes and separators of equal mass were stacked together in a sandwich structure, with the portion coated with electrode material covered in the middle by the PBI membrane, assembling a symmetrical device. Electrochemical tests were performed on the supercapacitor device.
[0072] Figure 7 The graph shows the electrochemical performance of PANI-SIR symmetric devices with different SIR mass ratios. Figure 7(a) shows the CV curves of the comparison samples with PANI:SIR:SP:PBI ratios of 70:10:10:10, 70:15:10:5, 70:20:5:5, and PANI:SP:PBI = 70:15:15 at a scan rate of 50 mV / s. It can be seen that the symmetrical devices at all four ratios exhibit excellent pseudocapacitive characteristics and highly reversible responses, with approximate CV curves. Figure 7 (b) The specific capacities at a current density of 1 A / g are 96 F / g, 101 F / g, 92 F / g, and 91 F / g, respectively. The CD curves show no significant voltage drop for any of the four values, indicating good conductivity of the materials. Figure 7 As shown in (c), using excessive SIR will introduce a large internal resistance to the device, resulting in a decrease in rate performance. Therefore, the recommended SIR content is 15 wt%. Figure 7 (c) and (d) show the capacity comparison of four devices with different mass ratios after 10,000 cycles at a current density of 5 A / g. When PANI:SIR:SP:PBI is 70:10:10:10, the capacity retention rate is 89%; when PANI:SIR:SP:PBI is 70:15:10:5, the capacity retention rate is 106%; when PANI:SIR:SP:PBI is 70:20:5:5, the capacity retention rate is 90%, while the capacity retention rate of the device with PANI:SP:PBI=70:15:15 is only 79%. Considering both rate capability and cycle performance, the improvement in device cycle stability is more significant when the SIR mass ratio is 15wt%, which is the mass ratio in Example 1.
[0073] Example 3:
[0074] 1. Preparation of PACM
[0075] Same as Example 1.
[0076] 2. Electrochemical performance testing of the three-electrode system
[0077] The PACM material obtained in this embodiment is used as a supercapacitor electrode material as follows: PACM is used as the active material, dissolved in deionized water, and coated onto graphite paper (1 cm × 2 cm), with a coating area of 1 cm². 2 The electrode was dried at 80℃ for 20 min on a heating stage and then used as the working electrode. Using Ag / AgCl as the reference electrode, Pt as the counter electrode, and 1MH₂SO₄ as the electrolyte, the electrochemical performance of the electrode material in a three-electrode system was tested.
[0078] Figure 8 As can be seen in (a) and (b) the SEM images of PACM-1 and PACM-2, the surface structure of the material becomes denser when the AD content is too high. Figure 8(b) The increase in mT content weakens the intermolecular forces of polymers, making the polymer chains more dispersed.
[0079] Figure 9 These are three-electrode chemical performance diagrams for different PACMs, PACM-1, and PACM-2. Figure 9 (a) It can be seen that all three electrode materials have excellent pseudocapacitance characteristic curves and good reversibility, with PACM exhibiting a larger closed curve area. Figure 9 (b) The CD curves of the three curves all show symmetrical charge and discharge curves and there is no obvious voltage drop, which indicates the excellent conductivity of the material itself. Figure 9 (c) PACM, PACM-1, and PACM-2 materials have specific capacities of 850 F / g, 723 F / g, and 756 F / g at a current density of 1 A / g, respectively. At a current density of 20 A / g, their rate performance is 84.3%, 84.7%, and 84.6%, respectively. With consistent rate performance, PACM exhibits a higher specific capacity. Therefore, PACM is chosen as the active material for the device, which is the active material for the device in Example 1.
[0080] Example 4:
[0081] 1. Preparation of PACM
[0082] Same as Example 1.
[0083] 2. Fabrication of PACM-SIR symmetrical supercapacitors
[0084] Same as Example 1.
[0085] 3. Fabrication of PACM symmetrical supercapacitors
[0086] Electrode slurry was prepared using PACM as the active material, SP as the conductive agent, and PBI as the binder in a mass ratio of 70:15:15, with N-methylpyrrolidone (NMP) as the solvent. A PBI membrane was used as the separator, and 6M H3PO4 was used as the electrolyte. Two electrode sheets with identical active material loadings were stacked with the separator, and the side of the PBI membrane covering the active material was assembled into a symmetrical device. The electrochemical performance of the device was then tested.
[0087] Figure 10 (a) is the CV image of the PACM-SIR symmetric device. The curves did not show obvious distortion at different scan rates, indicating that the device has excellent pseudocapacitive characteristics and redox reversibility. Figure 10 The CD curves in (b) and (c) are similar to those of the PACM-SIR device. The capacitance at 1A / g is 142.7F / g, which is lower than that of the PACM-SIR device (158F / g), and the rate performance is slightly worse than that of the PACM-SIR device. Figure 10 In (d), the capacity retention of the PACM symmetric device is only 72.4% after 30,000 cycles at a current density of 5 A / g, and its cycle stability is obviously worse than that of the device with added SIR.
[0088] Figure 11 The images show SEM images of the PACM electrode before and after cycling. It can be seen that the electrode cracks have expanded significantly after cycling, and the electrode surface is not as intact as that of the electrode after cycling in Example 1.
Claims
1. A method for preparing methyl-modified polyaniline, characterized in that: Methyl-modified polyaniline, denoted as PACM, is obtained by copolymerizing N-phenyl-p-phenylenediamine with m-methylaniline to introduce methyl functional groups onto the benzene ring, thereby weakening the intermolecular forces of the polymer and controlling the morphology of polyaniline. The preparation process includes the following steps: Step 1: Weigh 100-500 mg of N-phenyl-p-phenylenediamine, add it to a mixed solution of 5-20 mL of ethanol and 10-30 mL of 1 M HCl, stir well, and disperse by ultrasonication. This solution is labeled as solution A. Step 2: Weigh 100-500 mg of m-methylaniline, add 1 M HCl solution, stir until homogeneous, and ultrasonically disperse. This solution is labeled as solution B. Step 3: Weigh 300-1500 mg of APS, add 1 M HCl solution and stir well. Place at 0-5℃ for 10-50 min and record as solution C. Step 4: Pour the solution B obtained in Step 2 into the solution A obtained in Step 1, and ultrasonically disperse it at 0-5℃ for 10-30 min, then stir it at 0-5℃ for 10-40 min, controlling the mass ratio of N-phenyl-p-phenylenediamine and m-methylaniline to be 2:1 to 1:
2. Step 5: Slowly add solution C obtained in step 3 to the system in step 4 while stirring. Keep the addition process over 0.5-2 hours and continue stirring at 0-5°C for 4-12 hours. Step 6: The reaction solution obtained in Step 5 is centrifuged and washed with a mixture of deionized water and ethanol to remove residual acid and organic matter. The product is then freeze-dried and collected to obtain methyl-modified polyaniline, denoted as PACM.
2. A method for constructing a supercapacitor with excellent cycle stability, characterized in that: Using PACM prepared according to claim 1 as the active material, a binder, a conductive agent and a solvent are added to prepare an electrode slurry and an electrode is prepared; at the same time, PBI is used as a diaphragm and H3PO4 is used as an electrolyte. Two electrode plates with the active material coated on one side facing each other are stacked together with the diaphragm in a sandwich structure. The side loaded with the active material is attached to the middle PBI membrane to assemble a symmetrical device. The adhesive is composed of a hydrogen-bonded adhesive and polybenzimidazole, wherein the mass ratio of the active substance, hydrogen-bonded adhesive, conductive agent and polybenzimidazole is (70%-97%):(1%-15%):(1%-15%):(1%-10%). The hydrogen-bonded binder was prepared by the following method: (1) Take isophorone diisocyanate into a three-necked flask, add DMF, stir well, and label it as solution X; (2) Weigh a certain amount of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol), add dibutyltin dilaurate and DMF, stir evenly, and record it as solution Y; (3) Weigh a certain amount of imidazolidinyl urea, add DMF and stir well, and label it as solution Z; (4) Pour solution Y into solution X and heat for 4-8 hours with stirring; after the reaction is complete, add solution Z to the three-necked flask and continue heating and stirring for 8-16 hours. (5) After the reaction is completed, isopropyl ether is added to the product to produce a precipitate, which is collected by centrifugation. This precipitation-centrifugation operation is repeated twice, and the collected precipitate is dried in a vacuum drying oven. The precipitate is dissolved with NMP to prepare a hydrogen-bonding binder solution with a concentration of 10-50 wt%.
3. The construction method according to claim 2, wherein: Graphite paper is used as the current collector to coat the electrode slurry, and the electrode slurry coating area is >1 cm 2 .
4. The construction method according to claim 2, wherein: The loading mass of the single electrode active material is 0.1-5 mg / cm 2 .