A method for preparing a flexible electrode with photothermal effect and a supercapacitor

Abstract

The present invention discloses a method for preparing a flexible electrode with a photothermal effect and a supercapacitor, comprising the following steps: uniformly mixing a MXene dispersion and a BP dispersion to obtain a first mixed solution; adding a CNF dispersion to the first mixed solution and mixing uniformly to obtain a second mixed solution; performing a vacuum filtration self-assembly operation on the second mixed solution to prepare a MXene / BP / CNF self-assembled film; and directionally freeze-drying the MXene / BP / CNF self-assembled film to prepare a 3D MXene / BP / CNF flexible electrode. The present invention uses CNF as a one-dimensional structure optimization material, BP as a two-dimensional structure optimization material, and MXene as a two-dimensional structural main body, and prepares a 3D MXene / BP / CNF electrode based on a "2D-1D-2D" pre-assembly strategy. The electrode prepared by this method has a layered micro-arch structure and good mechanical flexibility. At the same time, the 3D MXene / BP / CNF flexible electrode prepared by treating the MXene / BP / CNF self-assembled film with a directionally frozen method can expose more active sites and provide fast ion transmission channels, thereby having excellent electrochemical performance.

Description

Technical Field

[0001] The present invention relates to a preparation method of a flexible electrode with photothermal effect and a supercapacitor, belonging to the technical field of supercapacitors. Background Art

[0002] With the rapid development of wearable electronic devices and electronic components, the requirements for their energy storage devices, such as lightweight, high power density, low cost and environmental friendliness, are becoming increasingly higher. As a new electrochemical energy storage device, flexible all-solid-state supercapacitors have attracted much attention due to their excellent performance, such as high power density, energy density and long service life. Finding high-performance electrode materials is the key to the development of high-performance supercapacitors. Compared with traditional carbon electrode materials, two-dimensional nanomaterials, such as MXene, have superior conductivity and hydrophilicity, as well as high capacity, and have good application value in supercapacitors. However, when these materials are assembled into electrodes, aggregation occurs, which reduces their electrochemical performance.

[0003] In addition to the aforementioned issues, the environmental adaptability of wearable flexible supercapacitors must also be considered. To address this issue, extensive work has been conducted to synthesize antifreeze gel electrolytes to improve ion transport between electrodes and electrolytes, thereby achieving good energy storage performance. However, complex manufacturing processes and high costs still limit their widespread application.

[0004] Solar energy is a new energy source with abundant reserves. Solar thermal conversion is a technology for collecting and utilizing solar energy, with advantages such as high conversion efficiency and low cost. Photothermal conversion has been applied in many fields such as desalination and photothermal medicine, but many potential applications remain to be explored. Integrating excellent mechanical properties, good electrochemical performance, and photothermal conversion performance into a supercapacitor system remains a significant challenge. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the existing technology and provide a method for preparing a flexible electrode with photothermal effect and a supercapacitor. By combining the "2D-1D-2D" pre-assembly and directional freeze-drying strategy, a 3D MXene / BP / CNF flexible electrode with photothermal effect and layered micro-arch structure is constructed, thereby improving the mechanical properties, photothermal properties and electrochemical properties of the supercapacitor electrode.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing a flexible electrode with a photothermal effect, comprising the following steps:

[0007] The MXene dispersion and the BP dispersion are uniformly mixed to obtain a first mixed solution;

[0008] Adding the CNF dispersion to the first mixed solution and mixing them evenly to obtain a second mixed solution;

[0009] The second mixed solution was subjected to a vacuum filtration self-assembly operation to prepare a MXene / BP / CNF self-assembled film;

[0010] Directional freeze drying of MXene / BP / CNF self-assembled films to prepare 3D MXene / BP / CNF flexible electrodes.

[0011] Furthermore, the mass ratio of BP and MXene was 1:10 to 1:10.5, and the mixture was stirred for 6 h to 10 h.

[0012] and / or, the mass ratio of BP to CNF is 1:1.25 to 1:1.3, and ultrasonic mixing is performed for 30 min-40 min.

[0013] Furthermore, the CNF dispersion was 5 mg mL -1 of cellulose nanofiber dispersion.

[0014] Furthermore, the liquid after ultrasonic mixing is subjected to a vacuum filtration self-assembly operation, comprising:

[0015] The ultrasonically mixed liquid is vacuum filtered to allow MXene, BP, and CNF to self-assemble to form a MXene / BP / CNF self-assembled film with a 3D network structure.

[0016] Furthermore, the liquid after ultrasonic mixing is subjected to a vacuum filtration self-assembly operation, comprising:

[0017] Nylon membrane was used as the filtration membrane.

[0018] Furthermore, the MXene / BP / CNF self-assembled film is directionally freeze-dried to prepare a 3D MXene / BP / CNF flexible electrode, comprising:

[0019] The MXene / BP / CNF self-assembled film was directionally frozen by liquid nitrogen and freeze-dried to prepare a dry 3D MXene / BP / CNF flexible electrode.

[0020] Furthermore, the freeze-drying time is 48h to 60h.

[0021] Furthermore, preparing the MXene dispersion includes:

[0022] Ti3AlC2 powder, LiF and HCl were mixed and the mixture was reacted at 35 °C for 24 h under continuous heating;

[0023] The obtained product was washed with deionized water and the solution was centrifuged until the pH value was neutral;

[0024] Ultrasonication and centrifugation were performed under nitrogen or argon conditions to obtain a MXene dispersion.

[0025] Further, preparing the BP dispersion comprises:

[0026] BP powder was dispersed in deionized water under nitrogen or argon conditions at a concentration of 8-10 mg / ml;

[0027] Ultrasonic stripping was performed at 480 W ultrasonic power for 24 h, and then centrifuged at 6000 rpm for 30 min. The supernatant was aspirated to obtain a BP dispersion.

[0028] In a second aspect, the present invention provides a supercapacitor having a flexible electrode prepared by the preparation method described in any one of the first aspects.

[0029] The beneficial effects achieved by the present invention are:

[0030] The present invention uses CNF as the one-dimensional structure optimization material, BP as the two-dimensional structure optimization material, and MXene as the two-dimensional structural main body, and prepares 3D MXene / BP / CNF flexible electrodes based on the "2D-1D-2D" pre-assembly strategy. The prepared electrode has a layered micro-arch structure and has good mechanical flexibility.

[0031] The present invention adopts a directional freezing method to treat the MXene / BP / CNF self-assembled film to prepare a 3D MXene / BP / CNF flexible electrode, which can expose more active sites, provide a fast ion transmission channel, and have excellent electrochemical performance.

[0032] The present invention constructs a micro-nano structure of 3D MXene / BP / CNF electrode and the photothermal synergistic effect between MXene and BP. The electrode material prepared has excellent photothermal effect and can significantly improve the electrochemical performance of supercapacitors. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The capacitance retention rate of a supercapacitor assembled with a 3DMXene / BP / CNF flexible electrode prepared by the method for preparing a flexible electrode with a photothermal effect provided in Example 1 of the present invention at different bending angles;

[0034] Figure 2 Schematic diagram of the mechanical flexibility mechanism of a 3DMXene / BP / CNF flexible electrode prepared by the method for preparing a flexible electrode with photothermal effect provided in Example 1 of the present invention;

[0035] Figure 3The supercapacitor assembled with 3DMXene / BP / CNF flexible electrodes prepared by the method for preparing a flexible electrode with photothermal effect provided in Example 1 of the present invention has a high thermal conductivity at 3 mA / cm 2 The area-specific capacitance and impedance of the flexible supercapacitor under different current densities and sunlight intensities;

[0036] Figure 4 This is a flow chart of a method for preparing a flexible electrode with photothermal effect provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The present invention will be further described below based on the accompanying drawings. The following examples are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0038] BP-black phosphorus; CNF-cellulose nanocellulose; MXene-titanium carbide Ti3C2T x (MXene).

[0039] The present invention provides a method for preparing a flexible supercapacitor electrode with photothermal effect and a supercapacitor, such as Figures 1 to 4 As shown, the present invention uses CNF as a one-dimensional structure optimization material, BP as a two-dimensional structure optimization material, and MXene as a two-dimensional structure main body, and prepares a 3D MXene / BP / CNF flexible electrode based on a "2D-1D-2D" pre-assembly strategy. The prepared electrode has a layered micro-arch structure and has good mechanical flexibility. At the same time, the present invention uses a directional freezing method to treat the MXene / BP / CNF self-assembled film to prepare a 3D MXene / BP / CNF flexible electrode, which can expose more active sites and provide a fast ion transmission channel, and has excellent electrochemical performance. The present invention constructs a micro-nano structure of a 3D MXene / BP / CNF flexible electrode, and the photothermal synergistic effect between MXene and BP, so that the prepared electrode material has an excellent photothermal effect, which can significantly improve the electrochemical performance of the supercapacitor.

[0040] Example 1:

[0041] The first embodiment of the present invention provides a method for preparing a flexible supercapacitor electrode with photothermal effect, such as Figure 4 As shown, the following steps are included:

[0042] Step 1: Preparation of monolayer MXene dispersion:

[0043] Ti3AlC2 powder (400 mesh, 2 g) was mixed with LiF (2 g) and HCl (9 M, 40 ml), and the mixture was reacted at 35 ° C for 24 hours under continuous stirring. The obtained product was washed with deionized water and centrifuged at 3500 rpm until the pH value of the solution was neutral. Finally, under nitrogen or argon protection, the product was ultrasonically treated for 1 hour and then centrifuged at 3500 rpm for 1 hour to obtain a monolayer MXene dispersion (5 mg mL -1 ).

[0044] Step 2: Preparation of BP dispersion:

[0045] BP powder was dispersed in deionized water at a concentration of 8 mg / mL under nitrogen or argon conditions and subjected to ultrasonic exfoliation for 24 h at an ultrasonic power of 480 W. Then, the mixture was centrifuged at 6000 rpm for 30 min, and the supernatant was collected to obtain a BP dispersion (2 mg / mL). -1 ).

[0046] Step 3: Preparation of 3D MXene / BP / CNF flexible electrodes:

[0047] 5 ml of BP dispersion (2 mg mL -1 ) was added to 20 ml of MXene dispersion (5 mg mL -1 ) and stirred for 6 h to mix well; then 2.5 ml CNF dispersion (5 mg mL -1 ) and ultrasonically mix for 30-40 minutes until uniformly mixed. Vacuum filtration was performed until no liquid was visible, resulting in a 3D MXene / BP / CNF preassembled membrane. This membrane was then directionally frozen with liquid nitrogen and freeze-dried for 48 hours to obtain a 3D MXene / BP / CNF flexible electrode.

[0048] Example 2:

[0049] The second embodiment of the present invention provides a method for preparing a flexible supercapacitor electrode with photothermal effect, such as Figure 4 As shown, the following steps are included:

[0050] Step 1: Preparation of monolayer MXene dispersion:

[0051] Ti3AlC2 powder (400 mesh, 2 g) was mixed with LiF (2 g) and HCl (9 M, 40 ml), and the mixture was reacted at 35 ° C for 24 hours under continuous stirring. The obtained product was washed with deionized water and centrifuged at 3500 rpm until the pH value of the solution was neutral. Finally, under nitrogen or argon protection, the product was ultrasonically treated for 1 hour and then centrifuged at 3500 rpm for 1 hour to obtain a monolayer MXene dispersion (5 mg mL-1 ).

[0052] Step 2: Preparation of BP dispersion:

[0053] BP powder was dispersed in deionized water at a concentration of 10 mg / mL under nitrogen or argon conditions and subjected to ultrasonic exfoliation for 24 h at an ultrasonic power of 480 W. Then, the mixture was centrifuged at 6000 rpm for 30 min, and the supernatant was collected to obtain a BP dispersion (2 mg / mL). -1 ).

[0054] Step 3: Preparation of 3D MXene / BP / CNF flexible electrodes:

[0055] 5 ml of BP dispersion (2 mg mL -1 ) was added to 21 ml of MXene dispersion (5 mg mL -1 ) and stirred for 10 h to mix well; then 2.6 ml CNF dispersion (5 mg mL -1 ) and ultrasonically mix for 30-40 minutes until uniformly mixed. Vacuum filtration was performed until no liquid was visible, resulting in a 3D MXene / BP / CNF preassembled membrane. This membrane was then directionally frozen with liquid nitrogen and freeze-dried for 60 hours to obtain a 3D MXene / BP / CNF flexible electrode.

[0056] Example 3:

[0057] The third embodiment of the present invention provides a method for preparing a flexible supercapacitor electrode with photothermal effect, such as Figure 4 As shown, the following steps are included:

[0058] Step 1: Preparation of monolayer MXene dispersion:

[0059] Ti3AlC2 powder (400 mesh, 2 g) was mixed with LiF (2 g) and HCl (9 M, 40 ml), and the mixture was reacted at 35 ° C for 24 hours under continuous stirring. The obtained product was washed with deionized water and centrifuged at 3500 rpm until the pH value of the solution was neutral. Finally, under nitrogen or argon protection, the product was ultrasonically treated for 1 hour and then centrifuged at 3500 rpm for 1 hour to obtain a monolayer MXene dispersion (5 mg mL -1 ).

[0060] Step 2: Preparation of BP dispersion:

[0061] BP powder was dispersed in deionized water at a concentration of 9 mg / mL under nitrogen or argon conditions and subjected to ultrasonic exfoliation for 24 h at an ultrasonic power of 480 W. Then, the mixture was centrifuged at 6000 rpm for 30 min, and the supernatant was collected to obtain a BP dispersion (2 mg / mL). -1 ).

[0062] Step 3: Preparation of 3D MXene / BP / CNF flexible electrodes:

[0063] 5 ml of BP dispersion (2 mg mL -1 ) was added to 20.5 ml of MXene dispersion (5 mg mL -1 ) and stirred for 8 h to mix evenly; then 2.55 ml CNF dispersion (5 mg mL -1 ) and ultrasonically mix for 30-40 minutes until uniformly mixed. Vacuum filtration was performed until no liquid was visible, resulting in a 3D MXene / BP / CNF preassembled membrane. This membrane was then directionally frozen with liquid nitrogen and freeze-dried for 50 hours to obtain a 3D MXene / BP / CNF flexible electrode.

[0064] Example 4:

[0065] Based on the 3D MXene / BP / CNF flexible electrode prepared by the preparation method of a flexible electrode with a photothermal effect provided in any one of Examples 1 to 3, Example 4 of the present invention provides a supercapacitor with the flexible electrode. During the preparation, 1g of PVA is first dissolved in 10ml of deionized water at 85°C, stirred and dissolved completely, and then cooled to room temperature. Then, 1g of concentrated sulfuric acid is added and stirred for 4h to obtain a transparent PVA / H2SO4 electrolyte.

[0066] The 3D MXene / BP / CNF flexible electrode was immersed in the above-mentioned gel electrolyte for 4 hours, then slowly removed, and the gelled electrode was sandwiched between two ungelled 3D MXene / BP / CNF flexible electrodes to prepare a sandwich-structured flexible supercapacitor.

[0067] Based on a supercapacitor provided in Example 4, a constant current charge and discharge test was performed:

[0068] The voltage range is 0-0.6V, and the charge and discharge current density is 5mA / cm 2 The cycling stability of the supercapacitor was characterized by GCD test with a scan rate of 50 mV / s and 6000 cycles.

[0069] The test results are shown in Table 1:

[0070] Table 1 Electrochemical performance test results

[0071]

[0072]

[0073] It can be seen from the experimental data in Table 1 that the 3D MXene / BP / CNF flexible electrode prepared in the present invention has excellent electrochemical performance.

[0074] The supercapacitor assembled with 3DMXene / BP / CNF flexible electrodes prepared according to the method for preparing a flexible electrode with photothermal effect provided in Example 1 of the present invention was subjected to a cycle performance test:

[0075] The supercapacitors were bent at different angles to test their cycle performance, such as Figure 1 As shown in Figure 2, the cycling performance of the supercapacitor was tested at different bending angles of 45°, 90°, and 135°. Figure 1 It can be seen that the capacitance retention rate of the supercapacitor at a bending angle of 45° is 96.8%, the capacitance retention rate at a bending angle of 90° is 94.1%, and the capacitance retention rate at a bending angle of 135° is 92.2%. Figure 1 It can be seen that the supercapacitor provided by the fourth embodiment of the present invention has excellent cycle stability under mechanical deformation.

[0076] The present invention designs the structure of the electrode to construct an electrode with good mechanical properties. The mechanism is as follows Figure 2 shown.

[0077] Figure 3 3mA / cm 2 The area specific capacitance and resistance of the flexible supercapacitor under different current density and different sunlight intensities are respectively irradiated on the supercapacitor with different intensities of sunlight. Figure 3 It can be seen that as the light intensity increases, the impedance Rs gradually decreases and the area specific capacitance gradually increases. This shows that the electrode material has excellent photothermal effect and electrochemical properties, which is of great significance for the design of new flexible supercapacitors.

[0078] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a flexible electrode with photothermal effect, characterized in that: The steps include: The MXene dispersion and the black phosphorus dispersion are uniformly mixed to obtain a first mixed solution; adding the cellulose nanofiber dispersion into the first mixed solution and mixing them evenly to obtain a second mixed solution; The second mixed solution is subjected to a vacuum filtration self-assembly operation to prepare a MXene / black phosphorus / cellulose nanofiber self-assembled film; Directional freeze drying of MXene / black phosphorus / cellulose nanofiber self-assembled films to prepare 3D MXene / black phosphorus / cellulose nanofiber flexible electrodes; The second mixed solution is subjected to a vacuum filtration self-assembly operation, comprising: The second mixed solution is vacuum filtered to allow the MXene, black phosphorus, and cellulose nanofibers to self-assemble to form a MXene / black phosphorus / cellulose nanofiber self-assembled membrane with a network structure; The mass ratio of black phosphorus to MXene is 1:10 to 1:10.5, and the mixture is stirred for 6 to 10 hours; and / or, the mass ratio of black phosphorus to cellulose nanofibers is 1:1.25 to 1:1.3, and ultrasonic mixing is performed for 30 min to 40 min; The cellulose nanofiber dispersion was 5 mg mL -1 cellulose nanofiber dispersion; Nylon membrane was used as the filtration membrane; Directional freeze drying of MXene / black phosphorus / cellulose nanofiber self-assembled films to prepare 3D MXene / black phosphorus / cellulose nanofiber flexible electrodes, including: The MXene / black phosphorus / cellulose nanofiber self-assembled film was frozen in liquid nitrogen and freeze-dried to prepare a dry 3DMXene / black phosphorus / cellulose nanofiber flexible electrode. The freeze-drying time is 48h to 60h; Preparation of MXene dispersion includes: Ti3AlC2 powder, LiF and HCl were mixed and the mixture was reacted at 35 °C for 24 h under continuous stirring; The obtained product was washed with deionized water and the solution was centrifuged until the pH value was neutral; Ultrasonication and centrifugation are performed under nitrogen or argon conditions to obtain a MXene dispersion; The preparation of the black phosphorus dispersion comprises: Under nitrogen or argon conditions, black phosphorus powder is dispersed in deionized water at a concentration of 8-10 mg / ml; ultrasonic stripping is performed at 480 W ultrasonic power for 24 hours, and then centrifuged at 6000 rpm for 30 minutes, and the supernatant is aspirated to obtain a black phosphorus dispersion.

2. A supercapacitor, characterized in that: A flexible electrode prepared by the preparation method according to claim 1.

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