Flexible film based on Prussian blue analogue / Mxene and PEDOT: PSS and preparation method and application thereof

Abstract

The invention provides a flexible film based on Prussian blue analogue / Mxene and PEDOT: PSS as well as a preparation method and application of the flexible film, and relates to the field of functional film materials. The method comprises the following steps: firstly, preparing an Mxene suspension; then, preparing Prussian blue analogue nano-particles; and finally, adding the Prussian blue analogue nanoparticles into the Mxene suspension, stirring to form a sandwich structure, then adding a polymer PEDOT: PSS, carrying out ultrasonic mixing, and carrying out suction filtration stripping to obtain the flexible film based on the Prussian blue analogue / Mxene and PEDOT: PSS. According to the invention, a long-chain structure of PEDOT: PSS is used for wrapping a PBAs / Mxene sandwich structure composite material, so that the whole system is stabilized, the mechanical property is enhanced, and meanwhile, a certain conductive network effect is achieved.

Description

Technical Field

[0001] The present invention relates to the field of functional thin film materials, and in particular to a flexible film based on a Prussian blue analogue / Mxene and PEDOT:PSS, and a preparation method and application thereof. Background Art

[0002] Against the backdrop of the increasingly serious global energy crisis and environmental pollution, the development of green and sustainable energy storage technologies has become an urgent need for the development of human society. In particular, driven by the rapid development of portable electronic devices, electric vehicles, and smart wearable devices, higher requirements are placed on energy storage devices with high power density, long cycle life, and fast charge and discharge capabilities. Supercapacitors, due to their excellent power performance, good cycle stability, and fast energy response speed, have become one of the most promising new energy storage devices after traditional batteries. However, the development of electrode materials with high specific capacity, high conductivity, and good structural stability remains the key to improving supercapacitor performance.

[0003] In recent years, two-dimensional materials have garnered widespread attention in the energy storage field due to their unique layered structure and high specific surface area. MXene, a class of two-dimensional transition metal carbon / nitrides, is obtained by selectively removing the A-layer elements (A is a Group III to V element, such as Al, Si, and Ga) from a precursor MAX phase. These materials have the general formula Mn+1XnTx (Mn is an early transition metal, such as Ti, Nb, or V; X is C / N; and n is an integer from 1 to 4). They exhibit high electronic conductivity, abundant surface functional groups, and tunable structural properties. These advantages contribute to their high specific capacitance and excellent rate performance in supercapacitors. However, MXene is susceptible to oxidation in aqueous environments and prone to layer stacking under dry conditions, resulting in a reduction in specific surface area and restricted ion diffusion pathways, thus compromising their overall electrochemical performance. Therefore, addressing this issue of layer stacking has become a major challenge in the practical application of MXene.

[0004] To overcome these issues, researchers have proposed a material composite strategy to manipulate the structure and properties of MXene. Prussian blue analogues (PBAs) are particularly well-suited for composite applications due to their three-dimensional open framework structure, large pores, and excellent redox activity. The metal ions in PBA-based materials can undergo reversible redox reactions, effectively enhancing the pseudocapacitive contribution and specific capacity of the composite material. Furthermore, PBAs themselves exhibit structural collapse, insufficient cycling stability, and poor conductivity. Composites with the highly conductive MXene facilitate their application in practical devices.

[0005] In order to further improve the structural stability and electron transfer efficiency of the composite system, the introduction of conductive polymers has become an effective strategy. Among them, PEDOT:PSS [poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid)] is one of the most widely studied water-soluble conductive polymers. It not only has good flexibility and film-forming properties, but also has high conductivity and chemical stability. The PEDOT chain provides an electron transfer path, while the PSS chain promotes the dispersion and compounding of the material in the aqueous system, which helps to improve the uniformity and stability of the composite system. In the composite structure, PEDOT:PSS can act as an "electronic bridge" to improve the connectivity of the overall conductive network; it can also act as a "flexible adhesive" to relieve the interfacial stress between materials and improve the mechanical stability and service life of the composite film.

[0006] A Chinese patent document discloses "Prussian blue analogue / Mxene composite electrode material and its in situ preparation method", with publication number CN 110783536A. This invention uses an in situ growth method to prepare a Prussian blue analogue / Mxene composite material. However, this invention cannot directly form a flexible material and be applied to flexible devices.

[0007] A search revealed patent CN119284923 A, which discloses a method and application for PEDOT-coated Prussian blue analogs. The method involves adding a Prussian blue analog and a commercial PEDOT:PSS dispersion to a dispersion system and stirring them uniformly; then slowly adding a precipitating solution to the dispersion system to precipitate the PEDOT on the surface of the Prussian blue analog. The material prepared in this patent is still a traditional powder material, and its future application in the field of flexible devices is unlikely. Summary of the Invention

[0008] The present invention aims to address key technical issues faced by existing MXene-based electrode materials in flexible devices, such as mechanical brittleness, electrode peeling, and conductivity degradation. The present invention provides a flexible film based on a Prussian blue analogue / MXene and PEDOT:PSS, as well as its preparation method and application. Ultimately, the present invention aims to prepare flexible electrodes by introducing a two-dimensional layered material, MXene, with ultrahigh conductivity, which is encapsulated in a Prussian blue analogue. This not only inhibits the volume expansion and disintegration of the Prussian blue analogue during the charge-discharge process, but also effectively curbs its aggregation. Furthermore, the PEDOT:PSS dispersion in the present invention is added to the mixed solution last, leveraging the long-chain structure of PEDOT:PSS to tightly lock the MXene and Prussian blue analogue together, enhancing the mechanical strength of the flexible electrode from the outset and effectively preventing breakage of the electrode material. Through the synergistic assembly of a Prussian blue analogue, MXene, and the polymer PEDOT:PSS, the present invention achieves a flexible electrode material with stable structure, excellent flexibility, and outstanding electrochemical performance.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] The present invention first provides a method for preparing a flexible film based on a Prussian blue analogue / Mxene and PEDOT:PSS, comprising:

[0011] Step 1: preparing MXene suspension;

[0012] Step 2: preparing Prussian blue analog nanoparticles;

[0013] Step 3: Add the Prussian blue analog nanoparticles prepared in step 2 to the MXene suspension in step 1 and stir to form a sandwich structure, then add the polymer PEDOT:PSS for ultrasonic mixing, and filter and peel off to obtain a flexible film based on Prussian blue analog / MXene and PEDOT:PSS.

[0014] Preferably, step one is specifically:

[0015] Step A: Deionized water and 36%-38% HCl solution were poured into a centrifuge tube and stirred. LiF powder was then added. After the powder dissolved, Ti3AlC2 powder (400 mesh) was weighed and added to the above solution for etching.

[0016] Step B: After the etching in step A is completed, the obtained solution is washed. After washing, deionized water is added to the centrifuge tube, and then vortexed for 40 minutes to obtain a single-layer flake MXene suspension.

[0017] Preferably, the mass ratio of the LiF powder and the Ti3AlC2 powder in step A is 1:1.

[0018] Preferably, the etching temperature in step A is 37° C., and the etching time is 24-48 hours.

[0019] Preferably, step 2 is specifically as follows:

[0020] Step a: K3[Fe 3+ (CN)6] solution was added to the mixed solution of nickel salt compound and sodium citrate and aged at room temperature to obtain a reaction solution;

[0021] Step b: centrifuging the reaction solution in step a, washing, freeze-drying and drying to obtain Prussian blue analog nanoparticles.

[0022] Preferably, the nickel salt compound in step a is nickel nitrate, nickel chloride or nickel acetate. Preferably, the mass ratio of the Prussian blue analog nanoparticles, Mxene and PEDOT:PSS in step 3 is 1:10:(1-2).

[0023] Preferably, the ultrasonic time in step three is 1-2h.

[0024] The application also provides a flexible film based on the Prussian blue analogues / Mxene and PEDOT:PSS prepared by the above preparation method.

[0025] The application also provides application of the above flexible film based on the Prussian blue analogues / Mxene and PEDOT:PSS in the field of flexible energy storage devices.

[0026] Advantages of the application

[0027] (1) Synergistic assembly of electrostatic driving and van der Waals force: the surface of PBA is positively charged, and the surface of MXene is negatively charged, and a preliminary composite structure is formed through electrostatic adsorption between the two, and the van der Waals force enhances the interlayer bonding force, so that the PBAs are uniformly dispersed between the MXene layers, effectively preventing excessive stacking of the MXene layers and formation of interface voids.

[0028] (2) High polymer flexible coating to enhance structural stability: on the basis of the PBAs / MXene composite structure, a PEDOT:PSS coating network is introduced. The conductive polymer segments in PEDOT:PSS are wrapped outside the composite structure and penetrate between the layers and particles, playing a dual role of “flexible skeleton” and “conductive adhesive”. Its excellent film-forming ability effectively improves the ductility and mechanical strength of the whole film, avoiding electrode performance degradation caused by local fracture.

[0029] (3) Structure control by vacuum filtration film forming process: the composite system is constructed into a sandwich type layered film through a vacuum filtration process, in which the MXene layers serve as “bread slices”, the PBA nanoparticles serve as “filling materials”, and the PEDOT:PSS serves as “hot melt adhesive” to encapsulate the entire sandwich. This method is simple to operate, and the film thickness and density can be controlled. The obtained film is flat, dense and flexible, and is suitable for peeling and application on a flexible substrate. Experimental results show that the flexible film of the application has excellent flexibility: the introduction of PEDOT:PSS significantly alleviates the mechanical instability problem of MXene caused by flocculation and brittleness. After repeated bending tests, the prepared film can be folded by 180° for multiple times without breaking, and has excellent stretchability and mechanical stress bearing capacity.

[0030] The material of the application has high conductivity: PEDOT:PSS and MXene cooperatively construct a multi-dimensional conductive network, the carrier migration path in the composite structure is short, the resistance is low, the electron conduction efficiency is effectively improved, and the conductivity can be up to 2000 S / cm or more.

[0031] (4) The method of the present application is green and environmentally friendly, and is suitable for aqueous systems: the whole process uses aqueous dispersion and vacuum filtration, and does not require organic solvents, so the process is safe and environmentally friendly, and is suitable for large-scale preparation. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a preparation flowchart of the present application.

[0033] Figure 2 is a scanning electron microscope (SEM) image of NiFePBAs in Example 1 of the present application.

[0034] Figure 3 is a scanning electron microscope (SEM) image of the surface of Mxene in Example 1 of the present application.

[0035] Figure 4 is a scanning electron microscope (SEM) image of the surface and cross-section of a commercial PEDOT:PSS filtration film.

[0036] Figure 5 is a macroscopic image of a Prussian blue analogue / Mxene composite film.

[0037] Figure 6 is a macroscopic image of a MXene and PEDOT:PSS composite film.

[0038] Figure 7 is a macroscopic image of Example 1 (PBAs:Mxene:PEDOT:PSS = 1:10:1) in the present application.

[0039] Figure 8 is a macroscopic image of Example 2 (PBAs:Mxene:PEDOT:PSS = 1:10:2) in the present application.

[0040] Figure 9 is a scanning electron microscope (SEM) image of the cross-section of a MXene film sample of Example 2.

[0041] Figure 10 is a scanning electron microscope (SEM) image of the cross-section of a MXene and PEDOT:PSS composite film.

[0042] Figure 11 is a scanning electron microscope (SEM) image of the cross-section and surface of Example 2.

[0043] Figure 12 is a CV curve of Example 1 and Example 2 and NiFePBAs electrode material in a three-electrode test at a scan rate of 10 mV s -1 -1.

[0044] Figure 13The electrode materials of Example 1 and Example 2 and NiFePBAs were tested with 1Ag -1 GCD curve. DETAILED DESCRIPTION

[0045] The present invention first provides a method for preparing a flexible film based on Prussian blue analogues / Mxene and PEDOT:PSS, such as Figure 1 Shown, including:

[0046] Step 1: preparing a MXene suspension; preferably comprising:

[0047] Step A: Take deionized water and a 36%-38% HCl solution, pour them into a centrifuge tube and stir, then add LiF powder, wait for the powder to dissolve, then weigh Ti3AlC2 powder (400 mesh), add it to the above solution for etching, the etching temperature is 37°C, and the etching time is 24-48h; the mass ratio of the LiF powder to the Ti3AlC2 powder is preferably 1:1.

[0048] Step B: After the etching in step A is completed, the obtained solution is washed. After washing, deionized water is added to the centrifuge tube, and then vortexed. The vortexing time is preferably 40 minutes to obtain a single-layer flake MXene suspension.

[0049] Step 2: preparing Prussian blue analog nanoparticles; preferably:

[0050] Step a: K3[Fe 3+ (CN) 6] solution is added to a mixed solution of nickel salt compound and sodium citrate, and aged at room temperature, wherein the room temperature aging time is preferably 24-36h; to obtain a reaction solution; the K3[Fe 3+ (CN)6], the molar ratio of the nickel salt compound and sodium citrate is preferably 8:12:15; the nickel salt compound is preferably nickel nitrate, nickel chloride or nickel acetate;

[0051] Step b: centrifuging the reaction solution in step a, washing, freeze-drying and drying to obtain Prussian blue analog nanoparticles.

[0052] Step 3: The Prussian blue analog nanoparticles prepared in Step 2 are added to the MXene suspension in Step 1 and stirred to form a sandwich structure. The polymer PEDOT:PSS is then added and ultrasonically mixed. The ultrasonication time is preferably 1-2 hours. The film is then filtered and stripped to obtain a flexible film based on the Prussian blue analog / MXene and PEDOT:PSS. The mass ratio of the Prussian blue analog nanoparticles, MXene, and PEDOT:PSS is preferably 1:10:(1-2).

[0053] The present invention also provides a flexible film based on Prussian blue analogue / Mxene and PEDOT:PSS obtained by the above preparation method.

[0054] The present invention also provides application of the flexible film based on Prussian blue analogue / Mxene and PEDOT:PSS in the field of flexible energy storage devices.

[0055] This invention incorporates MXene, a two-dimensional layered material with ultrahigh conductivity, into a Prussian blue analog. This not only inhibits the volume expansion and disintegration of the Prussian blue analog during the charge-discharge process, but also effectively curbs its aggregation. Furthermore, the PEDOT:PSS dispersion in this invention is added last to the mixed solution, leveraging the long-chain structure of PEDOT:PSS to tightly lock the MXene and Prussian blue analog together. This enhances the mechanical strength of the flexible electrode from the outset and effectively prevents breakage of the electrode material.

[0056] In order to better understand the present invention, the specific embodiments of the present invention will be described in detail below with reference to the examples.

[0057] It should be understood that the described embodiments are only for illustrating the present invention and should not be considered as limiting the scope of protection of the present invention. Without departing from the spirit and scope of the present invention, those skilled in the art may make various modifications and alternatives, and such modifications and alternatives should be considered to fall within the scope of protection of the present invention.

[0058] Example 1

[0059] Step A: Pour 5 ml of deionized water and 15 ml of 36%-38% HCl solution into a 100 ml centrifuge tube and stir at 500 rpm / min for 10 min. Then add 1 g of LiF powder and wait for the powder to dissolve for about 40 min. Then weigh 1 g of Ti3AlC2 powder (400 mesh) and add it to the above solution. Heat the temperature to 37°C and etch for 24 h while maintaining the speed at 500 rpm / min.

[0060] Step B: After the etching in step A is completed, the obtained solution is washed twice with water and ethanol alternately. After washing, about 40 ml of deionized water is added to the centrifuge tube and vortexed for 40 minutes to achieve the purpose of multi-layer Ti3C2T X The purpose of exfoliation is to obtain single few-layer flake MXene.

[0061] Step C: Take 1 ml of the suspension obtained in step B and vacuum filter it through a celgard filter membrane to obtain the concentration of the MXene suspension. In this embodiment, the concentration of the MXene suspension is weighed to be 4.4 mg / ml. Take 13.64 ml of it and the solid content of the suspension is 60 mg.

[0062] Step D: Take 0.264g of K3[Fe 3+ (CN)6] powder was dissolved in 60 mL of deionized water to prepare a solution; 0.30 g of nickel nitrate powder and 0.441 g of sodium citrate powder were dissolved in 40 mL of deionized water to prepare a solution.

[0063] Step E: Add 60 mL of K3[Fe 3+ The (CN)6] solution was added dropwise to 40 mL of nickel nitrate and sodium citrate solution; the mixture was aged at room temperature for 24 h at a rotation speed of 200 rpm / min.

[0064] Step F: Collect the precipitate. Transfer the solution from step E to a 50 ml centrifuge tube, centrifuge it at 8000 rpm for 5 minutes, and wash it three times with deionized water. Collect the precipitate after the last wash.

[0065] Step G: freeze-drying the sample. Take the precipitate collected in step F, place it in a freeze vacuum drying oven, and freeze-dry it for 36 hours. After drying, pure cubic Prussian blue analog nanoparticles can be obtained.

[0066] Step H: Weigh 6 mg of the powder obtained in Step G and add it to 13.64 mL of the suspension from Step C. Stir for 20 minutes to thoroughly mix and form a well-defined sandwich structure. Then, add 400 μL of 1.5% PEDOT:PSS in water and sonicate for 1 hour. The mixture is then vacuum filtered through a Celgard filter for approximately 6 hours to obtain an easily peelable PBAs@Mxene@PEDOT:PSS thin film with adjustable thickness.

[0067] Step I: The film sample obtained in step H, Ketjen black and PVDF (2% in NMP) were mixed into a slurry in a mass ratio of 7:2:1, stirred for 12 hours, and then coated on a carbon cloth treated with clean water. The slurry was then vacuum dried overnight. After complete drying, the carbon cloth was placed in a three-electrode test system for electrochemical performance testing, with the Pt sheet and Ag / AgCl as the counter electrode and reference electrode, respectively.

[0068] Figure 2 This is a scanning electron microscope (SEM) image of NiFePBAs obtained in step G of Example 1 of the present invention. Figure 2a represents the scanning graph of NiFePBAs obtained in step G in example 1 under 50000 times magnification, Figure 2 b represents the scanning graph of NiFePBAs under 150000 times magnification, from which it can be seen that the size of the prepared NiFePBAs is only about 120 nm, which is small and can be better inserted into the interlayer of MXene.

[0069] Figure 3 is the scanning electron microscope (SEM) graph of the surface of Mxene in example 1 of the application. From the graph, it can be seen that the size of the single-layer MXene sheet is large and complete, which can well wrap the NiFePBAs.

[0070] Figure 4 is the scanning electron microscope (SEM) graph of the surface and section of the commercial PEDOT:PSS filter film.

[0071] Example 2

[0072] Step A: 5ml of deionized water and 15ml of HCl solution with a content of 36%-38% were poured into a 100ml centrifuge tube, stirred at a speed of 500rpm / min for 10min, then 1g of LiF powder was added, and the powder was dissolved for about 40min, then 2g of Ti3AlC2 powder (400 mesh) was weighed and added to the above solution, and the temperature was heated to 37℃, etched for 48h and the speed was kept at 500rpm / min.

[0073] Step B: After the etching of step A was completed, the obtained solution was used to wash the sample with water and ethanol alternately for two times each, after the sample washing was completed, about 50ml of deionized water was added in the centrifuge tube, then vortexed for 40min, in order to achieve the purpose of peeling the multi-layer Ti3C2T X into single-layer sheet-shaped Mxene.

[0074] Step C: 1ml of the suspension obtained in step B was vacuum filtered through a celgard filter membrane, and the concentration of the Mxene suspension was obtained, the concentration of the Mxene suspension in this example was 8.8mg / ml by weighing, and 6.81ml of it was taken, and the solid content of the suspension was 60mg.

[0075] Step D: 0.264g of K3[Fe 3+ (CN)6] powder was dissolved in 60mL of deionized water to prepare a solution; 0.285g of nickel chloride powder and 0.441g of sodium citrate powder were dissolved in 40mL of deionized water to prepare a solution.

[0076] Step E: 60mL of K3[Fe 3+The (CN)6] solution was added dropwise to 40 mL of nickel acetate and 0.441 g of sodium citrate solution; the mixture was aged at room temperature for 24 h at a rotation speed of 200 rpm / min.

[0077] Step F: Collect the precipitate. Transfer the solution from step E to a 50 ml centrifuge tube, centrifuge it at 8000 rpm for 5 minutes, and wash it three times with deionized water. Collect the precipitate after the last wash.

[0078] Step G: freeze-drying the sample. Take the precipitate collected in step F, place it in a freeze vacuum drying oven, and freeze-dry it for 36 hours. After drying, pure cubic Prussian blue analog nanoparticles can be obtained.

[0079] Step H: Weigh 6 mg of the powder obtained in Step G and add it to 6.81 mL of the suspension from Step C. Stir for 20 minutes to thoroughly mix and form a well-defined sandwich structure. Then, add 800 μL of 1.5% PEDOT:PSS in water and sonicate for 1 hour. The mixture is then vacuum filtered through a Celgard filter for approximately 8 hours to obtain an easily peelable PBAs@Mxene@PEDOT:PSS thin film with adjustable thickness.

[0080] Step I: The film sample obtained in step H, Ketjen black and PVDF (2% in NMP) were mixed into a slurry in a mass ratio of 7:2:1, stirred for 12 hours, and then coated on a carbon cloth treated with clean water. The slurry was then vacuum dried overnight. After complete drying, the carbon cloth was placed in a three-electrode test system for electrochemical performance testing, with the Pt sheet and Ag / AgCl as the counter electrode and reference electrode, respectively.

[0081] Figure 9 This is a scanning electron microscope (SEM) image of the cross-section of the MXene film sample of Example 2. It can be seen from the figure that MXene can obtain an ideal layer stacking structure after vacuum filtration.

[0082] Figure 11 : is a scanning electron microscope (SEM) image of the side section and surface of the thin film sample obtained in step H of Example 2. Figure 11 a represents a cross-sectional scan of the film sample of Example 2, Figure 11 b represents the surface scanning image of the film sample of Example 2. It can be seen from the figure that the composite flexible electrode has achieved the ideal microstructure of MXene-coated NiFePBAs.

[0083] Figure 12 The electrode materials of Examples 1 and 2 and NiFePBAs were tested at 10 mV s in the three-electrode test. -1CV curves at different scan rates. It can be seen from the figure that the specific capacity of the two composite flexible electrodes is higher than that of NiFePBAs, and the specific capacity of the flexible electrode with PBAs: MXene: PEDOT: PSS = 1:10:2 is 248.02 F g -1 , which is higher than the flexible electrode of PBAs:Mxene:PEDOT:PSS=1:10:1 (237.65F g) -1 .

[0084] Figure 13 The electrode materials of Example 1 and Example 2 and NiFePBAs were tested with 1Ag -1 GCD curve. It can be seen from the figure that the specific capacity of the two composite flexible electrodes is higher than that of NiFePBAs, and the specific capacity of the flexible electrode with PBAs: Mxene: PEDOT: PSS = 1:10:2 is 219.33F g -1 , which is higher than the flexible electrode of PBAs:Mxene:PEDOT:PSS=1:10:1 by 197.21.

[0085] Example 3

[0086] Step A: Pour 5 ml of deionized water and 15 ml of 36%-38% HCl solution into a 100 ml centrifuge tube and stir at 500 rpm / min for 10 min. Then add 1 g of LiF powder and wait for the powder to dissolve for about 40 min. Then weigh 1 g of Ti3AlC2 powder (400 mesh) and add it to the above solution. Heat the temperature to 37°C and etch for 24 h while maintaining the speed at 500 rpm / min.

[0087] Step B: After the etching in step A is completed, the obtained solution is washed twice with water and ethanol alternately. After washing, about 40 ml of deionized water is added to the centrifuge tube and vortexed for 40 minutes to achieve the purpose of multi-layer Ti3C2T X The purpose of exfoliation is to obtain single few-layer flake MXene.

[0088] Step C: Take 1 ml of the suspension obtained in step B and vacuum filter it through a celgard filter membrane to obtain the concentration of the Mxene suspension. In the present invention, the concentration of the Mxene suspension is weighed to be 4.6 mg / ml. Take 13.04 ml of it, and the solid content of the suspension is 60 mg.

[0089] Step D: Take 0.527g of K3[Fe 3+ (CN)6] powder was dissolved in 60 mL of deionized water to prepare a solution; 0.597 g of nickel acetate powder and 0.882 g of sodium citrate powder were dissolved in 40 mL of deionized water to prepare a solution.

[0090] Step E: Add 60 mL of K3[Fe 3+ The (CN)6] solution was added dropwise to 40 mL of nickel acetate and 0.441 g of sodium citrate solution; the mixture was aged at room temperature for 36 h at a rotation speed of 200 rpm / min.

[0091] Step F: Collect the precipitate. Transfer the solution from step E to a 50 ml centrifuge tube, centrifuge it at 8000 rpm for 5 minutes, wash it three times with deionized water, and finally wash it once with anhydrous ethanol. Collect the precipitate after the reaction.

[0092] Step G: Drying the sample: Take the precipitate collected in step F, place it in an oven, and heat dry it for 36 hours. After drying, pure cubic Prussian blue analog nanoparticles can be obtained.

[0093] Step H: Weigh 6 mg of the powder obtained in Step G and add it to 13.64 mL of the suspension from Step C. Stir for 20 minutes to thoroughly mix and form a well-defined sandwich structure. Then, add 800 μL of 1.5% PEDOT:PSS in water and sonicate for 1 hour. The mixture is then vacuum filtered through a Celgard filter for approximately 10 hours to obtain an easily peelable PBAs@Mxene@PEDOT:PSS thin film with adjustable thickness.

[0094] Step I: The film sample obtained in step H, Ketjen black and PVDF (2% in NMP) were mixed into a slurry in a mass ratio of 7:2:1, stirred for 12 hours, and then coated on a carbon cloth treated with clean water. The slurry was then vacuum dried overnight. After complete drying, the carbon cloth was placed in a three-electrode test system for electrochemical performance testing, with the Pt sheet and Ag / AgCl as the counter electrode and reference electrode, respectively.

[0095] Example 4

[0096] Step A: Pour 5 ml of deionized water and 15 ml of 36%-38% HCl solution into a 100 ml centrifuge tube and stir at 500 rpm / min for 10 min. Then add 1 g of LiF powder and wait for the powder to dissolve for about 40 min. Then weigh 1 g of Ti3AlC2 powder (400 mesh) and add it to the above solution. Heat the temperature to 37°C and etch for 24 h while maintaining the speed at 500 rpm / min.

[0097] Step B: After the etching in step A is completed, the obtained solution is washed twice with water and ethanol alternately. After washing, about 40 ml of deionized water is added to the centrifuge tube and vortexed for 40 minutes to achieve the purpose of multi-layer Ti3C2T XThe purpose of exfoliation is to obtain single few-layer flake MXene.

[0098] Step C: Take 1 ml of the suspension obtained in step B and vacuum filter it through a celgard filter membrane to obtain the concentration of the Mxene suspension. In the present invention, the concentration of the Mxene suspension is weighed to be 4.4 mg / ml. Take 13.64 ml of it, and the solid content of the suspension is 60 mg.

[0099] Step D: Take 0.264g of K3[Fe 3+ (CN)6] powder was dissolved in 60 mL of deionized water to prepare a solution; 0.285 g of nickel chloride powder and 0.441 g of sodium citrate powder were dissolved in 40 mL of deionized water to prepare a solution.

[0100] Step E: Add 60 mL of K3[Fe 3+ The (CN)6] solution was added dropwise to 40 mL of nickel chloride and sodium citrate solution; the mixture was aged at room temperature for 24 h at a rotation speed of 200 rpm / min.

[0101] Step F: Collect the precipitate. Transfer the solution from step E to a 50 ml centrifuge tube, centrifuge it at 8000 rpm for 5 minutes, and wash it three times with deionized water. Collect the precipitate after the last wash.

[0102] Step G: freeze-drying the sample. Take the precipitate collected in step F, place it in a freeze vacuum drying oven, and freeze-dry it for 36 hours. After drying, pure cubic Prussian blue analog nanoparticles can be obtained.

[0103] Step H: Weigh 6 mg of the powder obtained in Step G and add it to 13.64 mL of the suspension from Step C. Stir for 20 minutes to thoroughly mix and form a well-defined sandwich structure. Then, add 800 μL of 1.5% PEDOT:PSS in water and sonicate for 1 hour. The mixture is then vacuum filtered through a Celgard filter for approximately 6 hours to obtain an easily peelable PBAs@Mxene@PEDOT:PSS thin film with adjustable thickness.

[0104] Step I: The film sample obtained in step H, Ketjen black and PVDF (2% in NMP) were mixed into a slurry in a mass ratio of 7:2:1, stirred for 12 hours, and then coated on a carbon cloth treated with clean water. The slurry was then vacuum dried overnight. After complete drying, the carbon cloth was placed in a three-electrode test system for electrochemical performance testing, with the Pt sheet and Ag / AgCl as the counter electrode and reference electrode, respectively.

[0105] Figure 5This is a macroscopic image of flexible electrodes prepared with different ratios of MXene and NiFePBAs. Numbers 1-6 in the figure represent MXene to NiFePBAs ratios of 15:1, 13:1, 10:1, 7:1, 5:1, and 3:1, respectively. Taking sample No. 1 as an example, 13.64 ml of MXene at a concentration of 4.4 mg / ml from Example 4 was taken, containing a total mass of 60 mg of MXene. Then, 4 mg of NiFePBAs was taken, and the two were fully halved and evenly mixed. After vacuum filtration, a thin film electrode with a 15:1 ratio of MXene to NiFePBAs was obtained. The remaining ratios only required adjusting the NiFePBAs content. It can be seen that as the MXene content continued to increase, the flexible electrode became more complete and its flexibility also increased to a certain extent. Since the capacity of the electrode is primarily provided by NiFePBAs, the ratio of MXene to NiFePBAs was ultimately set at 10:1.

[0106] Figure 6 This is a macroscopic picture of thin films prepared with different ratios of MXene and PEDOT:PSS. The numbers 1-5 in the figure represent the ratios of MXene to PEDOT:PSS of 1:0, 20:1, 15:1, 10:1 and 5:1, respectively. Figure 6 Taking Sample 2 in Example 4 as an example, 13.64 ml of the 4.4 mg / ml MXene solution (containing 60 mg of MXene) was added. Then, 200 μl of PEDOT:PSS (1.5% in water) was mixed thoroughly and vacuum filtered to produce a thin film electrode with a 20:1 MXene to PEDOT:PSS ratio. The remaining ratios were adjusted by adjusting the amount of PEDOT:PSS. The addition of PEDOT:PSS improved the film's mechanical properties. However, since PEDOT:PSS has lower conductivity than MXene, the amount of PEDOT:PSS added needs to be carefully considered. Based on a combination of flexibility and conductivity, MXene to PEDOT:PSS ratios of 10:1 and 5:1 showed promising results.

[0107] Figure 10 This is a scanning electron microscope (SEM) image of the side cross-section of the MXene and PEDOT:PSS composite film. The ratio of MXene to PEDOT:PSS is 10:1. By comparison Figure 9 It can be seen that by adding PEDOT:PSS to the MXene film, the MXene layers are stacked more densely.

[0108] Figure 7 This is a macroscopic picture of the flexible electrode of Example 1, where Figure 7 a is a flattened electrode photo. Figure 7 b is a photo of the folded electrode. Figure 8 This is a macroscopic picture of the flexible electrode of Example 2, where Figure 8 a is a flattened electrode photo. Figure 8 b is a photo of the folded electrode, where the ratios of MXene:NiFePBAs:PEDOT:PSS are 10:1:1 and 10:1:2 respectively; for comparison Figure 7 and Figure 8 , it can be seen that when the ratio of MXene:NiFePBAs:PEDOT:PSS is 10:1:1, the integrity and flexibility of the flexible electrode are optimal, and the same results are obtained in the electrochemical test.

Claims

1. A method for preparing a flexible film based on Prussian blue analogue / Mxene and PEDOT:PSS, characterized in that: include: Step 1: preparing MXene suspension; Step 2: preparing Prussian blue analog nanoparticles; Step 3: Add the Prussian blue analog nanoparticles prepared in step 2 to the MXene suspension in step 1 and stir to form a sandwich structure, then add the polymer PEDOT:PSS for ultrasonic mixing, and filter and peel off to obtain a flexible film based on Prussian blue analog / MXene and PEDOT:PSS.

2. The method for preparing a flexible film based on Prussian blue analogue / Mxene and PEDOT:PSS according to claim 1, characterized in that: Step 1 is as follows: Step A: Deionized water and 36%-38% HCl solution were poured into a centrifuge tube and stirred. LiF powder was then added. After the powder dissolved, Ti3AlC2 powder (400 mesh) was weighed and added to the above solution for etching. Step B: After the etching in step A is completed, the obtained solution is washed. After washing, deionized water is added to the centrifuge tube, and then vortexed for 40 minutes to obtain a single-layer flake MXene suspension.

3. The method for preparing a flexible film based on a Prussian blue analogue / MXene and PEDOT:PSS according to claim 2, wherein the mass ratio of the LiF powder to the Ti3AlC2 powder in step A is 1:

1.

4. The method for preparing a flexible film based on Prussian blue analogue / Mxene and PEDOT:PSS according to claim 1, characterized in that: The etching temperature in step A is 37° C., and the etching time is 24-48 hours.

5. The method for preparing a flexible film based on Prussian blue analogue / Mxene and PEDOT:PSS according to claim 1, characterized in that: Step 2 is as follows: Step a: K3[Fe 3+ (CN)6] solution was added to the mixed solution of nickel salt compound and sodium citrate and aged at room temperature to obtain a reaction solution; Step b: centrifuging the reaction solution in step a, washing, freeze-drying and drying to obtain Prussian blue analog nanoparticles.

6. The method for preparing a flexible film based on Prussian blue analogue / Mxene and PEDOT:PSS according to claim 5, characterized in that: The nickel salt compound described in step a is nickel nitrate, nickel chloride or nickel acetate.

7. The method for preparing a flexible film based on Prussian blue analogue / Mxene and PEDOT:PSS according to claim 1, characterized in that: The mass ratio of the Prussian blue analog nanoparticles, Mxene and PEDOT:PSS described in step 3 is 1:10:(1-2).

8. The method for preparing a flexible film based on Prussian blue analogue / Mxene and PEDOT:PSS according to claim 1, characterized in that: The ultrasonic time described in step 3 is 1-2h.

9. A flexible film based on Prussian blue analogue / MXene and PEDOT:PSS obtained by the preparation method according to claim 1.

10. Use of the flexible film based on Prussian blue analogue / Mxene and PEDOT:PSS according to claim 9 in the field of flexible energy storage devices.

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