Halogen perovskite / mxene composite energy storage electrode material and preparation method and application thereof

Abstract

This invention discloses a halide perovskite / MXene composite energy storage electrode material, its preparation method, and its application, belonging to the field of energy storage material technology. The electrode material comprises the following raw materials in parts by weight: 1-4 parts halide perovskite and 5 parts two-dimensional MXene. The preparation method involves first preparing halide perovskite using formamidinium hydroiodate and lead iodide as raw materials, then preparing two-dimensional MXene using lithium fluoride and MAX phase Ti3AlC2 powder as raw materials. Finally, the two materials are mixed, ground, and subjected to a series of post-treatments to obtain the final product. This invention solves the problem of the unstable application of halide perovskite FAPbI3 in the field of electrochemical energy storage, and overcomes the technical bottlenecks of interlayer stacking and surface oxidation of MXene materials. It also achieves bidirectional enhancement of the performance of both materials, opening up a new technical path for the application of unstable halide perovskites in the field of electrochemical energy storage.

Description

Technical Field

[0001] This invention relates to the field of energy storage materials technology, and more specifically to a halide perovskite / MXene composite energy storage electrode material, its preparation method, and its application. Background Technology

[0002] Supercapacitors, also known as electrochemical capacitors, gold capacitors, or farad capacitors, are a new type of energy storage device that falls between traditional capacitors and rechargeable batteries. They possess both the rapid charging and discharging characteristics of capacitors and the energy storage characteristics of batteries. With their ultra-high power density, extremely fast charge and discharge rates, and excellent cycle stability, supercapacitors have shown broad application prospects in fields such as rail transportation, smart grids, portable electronic devices, and new energy vehicles. However, insufficient energy density remains the core bottleneck restricting the large-scale application of supercapacitors. Electrode materials, as key components of supercapacitors, directly determine the energy output level of the device through their microstructure and intrinsic electrochemical activity.

[0003] In recent years, halide perovskite materials (ABX3) have achieved great success in the photovoltaic and optoelectronic fields due to their properties such as low-temperature solution processing, high carrier mobility, and excellent defect tolerance. Among them, α-FAPbI3, with its ideal band gap (~1.48 eV) closest to the Shockley-Queisser limit and excellent structural symmetry, is considered one of the most promising photovoltaic materials. However, research on the application of α-FAPbI3 in electrochemical energy storage is almost non-existent. The key technological bottleneck it faces lies in:

[0004] (1) Intrinsic stability defects: α-FAPbI3 is extremely sensitive to moisture. When the air humidity is >30% or when it comes into contact with aqueous electrolyte, it is very easy to undergo irreversible phase transformation, generating electrochemically inert δ-FAPbI3, or decomposing into PbI2, resulting in a sharp loss of electrochemical activity. (2) Insufficient conductivity: α-FAPbI3 is a semiconductor material with a band gap of about 1.2~1.5 eV. Its electron transport capability is much lower than that of carbon materials or transition metal carbides. When used alone as an electrode material for supercapacitors, it has poor rate performance and high internal resistance. (3) Lack of effective electrode structure design: Existing research on the stability improvement of FAPbI3 (such as additive engineering and ionic liquid modification) mainly focuses on the illumination and humidity conditions of photovoltaic devices, without involving the repeated ion insertion / extraction and strong polarization electric field damage mechanism of perovskite lattice under electrochemical conditions. There is no mature technical solution that can be directly applied to the electrode of supercapacitor.

[0005] Meanwhile, two-dimensional transition metal carbides MXene (in Ti3C2T) xTi3C2T (represented by Ti3C2T) has become a research hotspot in the field of supercapacitors due to its metallic conductivity, hydrophilic surface, and high volume capacitance. x In practical applications, two major challenges remain: first, nanosheets are prone to self-stacking during drying and film formation, significantly reducing electrochemical active sites; second, Ti3C2T… x When circulating in an aqueous electrolyte for a long time, Ti atoms on the surface are easily oxidized to form TiO2, which leads to capacitance decay.

[0006] Therefore, how to introduce α-FAPbI3, which has poor stability but huge theoretical pseudocapacitance potential, into the supercapacitor system, while solving the interlayer stacking and oxidation problems of MXene, is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the purpose of the present invention is to provide a halide perovskite / MXene composite energy storage electrode material, its preparation method and application, so as to overcome the shortcomings of the prior art.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A halide perovskite / MXene composite energy storage electrode material comprises the following raw materials in parts by weight: 1-4 parts halide perovskite and 5 parts two-dimensional MXene.

[0009] Product feature parameters: Specific capacitance: ≥550 F / g at a current density of 1 A / g (three-electrode system, 2M H2SO4 electrolyte); Cyclic stability: Capacitance retention ≥ 80% after 15,000 cycles; Interlayer spacing: Ti3C2T after composite x Ti3C2T before interlayer spacing treatment x Expand by 0.1~0.3 Å.

[0010] Furthermore, the aforementioned halide perovskite / MXene composite energy storage electrode material comprises the following raw materials in parts by weight: 3 parts halide perovskite and 5 parts two-dimensional MXene.

[0011] Furthermore, the aforementioned halide perovskite is high-purity α-FAPbI3.

[0012] Furthermore, the X-ray diffraction pattern of the high-purity α-FAPbI3 shows characteristic diffraction peaks at 2θ=14.2°±0.2° and 28.4°±0.2° belonging to the (100) and (200) crystal planes, respectively, and there are no characteristic diffraction peaks belonging to δ-FAPbI3 at 2θ=11.8°±0.2°.

[0013] Furthermore, the aforementioned two-dimensional MXene is a few-layer Ti3C2T x Nanosheets, in which T x Represents a surface terminal functional group, including at least one of -F, -O and -OH.

[0014] Furthermore, the aforementioned two-dimensional MXene coats the surface of the halide perovskite to form a continuous conductive network structure, and some of the halide perovskite is embedded between the two-dimensional MXene layers, increasing its interlayer spacing.

[0015] A method for preparing the above-mentioned halide perovskite / MXene composite energy storage electrode material specifically includes the following steps: (1) Preparation of halide perovskite Formamidin hydroiodide was mixed with lead iodide, an organic solvent was added, the mixture was stirred, filtered, heated, crystallized, washed, filtered again, and dried to obtain black α-FAPbI3 powder. (2) Preparation of two-dimensional MXene Lithium fluoride was added to hydrochloric acid and stirred. MAX phase Ti3AlC2 powder was then added, and the mixture was reacted in an oil bath. After centrifugation, the precipitate was collected, washed, and water was added. The precipitate was then ultrasonically exfoliated, supplemented with manual oscillation exfoliation. After centrifugation again, the dark green supernatant was collected and freeze-dried to obtain a few-layer Ti3C2T. x Nanoparticle powder; (3) Preparation of halide perovskite / MXene composite energy storage electrode material Black α-FAPbI3 powder and few-layer Ti3C2T x Nanosheet powders are mixed and ground, a dispersing solvent is added, and the mixture is ultrasonically treated. The resulting material is deposited on a porous substrate, filtered, vacuum dried, and the film is peeled off to obtain a halide perovskite / MXene composite energy storage electrode material (self-supporting Ti3C2T). x / α-FAPbI3 composite thin film electrode material).

[0016] Further, in step (1) above, the ratio of formamidinium hydroiodide (FAI), lead iodide (PbI2), and organic solvent is 1 mmol : (0.95~1.05) mmol : (5~20) mL, preferably 1 mmol : 1 mmol : 10 mL; the organic solvent is selected from at least one of γ-valerolactone (GVL), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO), preferably γ-valerolactone (GVL); the stirring temperature is 50~70℃, preferably 60℃, and the stirring time is 6~24 h, preferably 12 h; the filtration equipment is 0.22~0.45 μm filter membrane; the specific heating process is as follows: the precursor solution obtained after filtration is placed in a constant temperature environment of 50~70℃, and the temperature is programmed to rise to 90~100℃ at a heating rate of 2~10℃ / h, preferably to 95℃ at a heating rate of 4℃ / h; the crystallization time is 12~48 h, preferably 24 h; the cleaning reagent is hot cyclohexane at 80~100℃, preferably hot cyclohexane at 95℃; the drying equipment is an oven at a temperature of 140~180℃, preferably 160℃, for a time of 1~3 h, preferably 2 h.

[0017] Further, in step (2) above, the concentration of hydrochloric acid (HCl) is 6~12 M, preferably 12 M; the ratio of lithium fluoride (LiF), hydrochloric acid, and MAX phase Ti3AlC2 powder is (1.5~2.0) g : 20 mL : 1 g, preferably 1.6 g : 20 mL : 1 g; the reaction temperature in the oil bath is 40~60℃, preferably 50℃, and the time is 20~30 h, preferably 24 h; the centrifugation speed is 3000~4000 rpm, preferably 3500 rpm, and the time is 5~15 min, preferably 10 min; the washing process is as follows: the precipitate is washed 1~3 times with 1M HCl, and then repeatedly washed with deionized water until the pH of the supernatant is ≥ 6; the solid-liquid ratio of water added is 1 g : (100~500) mL, preferably 1 g : 200 mL; the ultrasonic stripping power is 100~300 W, preferably 200 W. W, the time is 1~4 h, preferably 2 h; the manual shaking peeling time is 5~15 min, preferably 10 min; the speed of the second centrifugation is 3000~4000 rpm, preferably 3500 rpm, and the time is 5~15 min, preferably 10 min; the freeze drying time is 48~96 h.

[0018] Furthermore, in step (3) above, black α-FAPbI3 powder and few-layer Ti3C2T xThe ratio of nanosheet powder to dispersing solvent is (10~40) mg : 50 mg : (10~50) mL, preferably 30 mg : 50 mg : 20 mL; the mixing and grinding equipment is a mortar and pestle, and the time is 5~15 min, preferably 10 min; the dispersing solvent is selected from at least one of anhydrous ethanol, deionized water, and isopropanol, preferably anhydrous ethanol; the ultrasonic treatment power is 100~300 W, preferably 200 W, and the time is 5~30 min, preferably 10 min; the deposition equipment is a vacuum filtration device; the porous substrate is selected from nanoporous polypropylene membrane, polytetrafluoroethylene membrane, or mixed cellulose ester membrane, with a pore size of 0.02~0.22 μm, preferably Celgard 3501 (pore size 0.064 μm); the vacuum degree of filtration is -0.1~-0.05 MPa, preferably -0.08 MPa. MPa; The vacuum drying equipment is a vacuum drying oven, with a temperature of 50~80℃, preferably 60℃, and a time of 6~24 h, preferably 12 h.

[0019] This invention also claims the application of the above-described halide perovskite / MXene composite energy storage electrode material or the halide perovskite / MXene composite energy storage electrode material prepared by the above-described method in the preparation of supercapacitors.

[0020] A supercapacitor comprising the above-mentioned halide perovskite / MXene composite energy storage electrode material or the halide perovskite / MXene composite energy storage electrode material prepared by the above-mentioned preparation method.

[0021] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows: Advantage 1: For the first time, halide perovskites have been stably applied in supercapacitors, significantly improving phase stability and wet stability under electrochemical conditions.

[0022] Specific performance: The α-FAPbI3 / Ti3C2T prepared in this invention... x The composite thin-film electrode operated stably in a 2M H2SO4 aqueous electrolyte, and no characteristic diffraction peaks of δ-FAPbI3 were detected in the XRD pattern, indicating that α-FAPbI3 did not undergo a phase transition in the composite system.

[0023] Source technology: Ti3C2T x The physical coating structure of α-FAPbI3 forms a physical barrier, preventing water erosion.

[0024] Advantage 2: Significantly improves specific capacitance and rate performance, breaking through the limitations of Ti3C2T. x MXene interlayer stacking bottleneck.

[0025] Specific performance: The optimal ratio (5:3) composite thin film electrode achieves a specific capacitance of 583.0 F / g at 1 A / g, which is higher than that of pure Ti3C2T. x MXene (281.86 F / g) improved by 106.8%; it also maintained a high capacitance retention rate at a high current density of 5 A / g.

[0026] Source of technical points: FAPbI3 particles are inserted into Ti3C2T as "nanospacers". x Interlayer. Kinetic analysis showed that the surface capacitance contribution rate of the composite thin film electrode reached 83.8% (2 mV / s), significantly higher than that of pure Ti3C2T. x MXene (64.5%) demonstrates a significant increase in pseudocapacitive active sites.

[0027] Cause: Increased interlayer spacing reduces H + The intercalation and diffusion resistance of electrolyte ions is reduced; simultaneously, the introduction of FAPbI3 increases the Ti3C2T x The ion-accessible surface area between MXene layers allows more Ti sites to participate in redox reactions.

[0028] Advantage 3: Ultra-long cycle stability, significantly better than existing Ti3C2T x MXene-based and perovskite-based energy storage devices.

[0029] Specifically, the zinc-ion hybrid supercapacitor based on composite thin film maintained a capacitance retention rate of up to 82.9% after 15,000 charge-discharge cycles at 1 A / g.

[0030] Technical point: Interfacial coupling inhibits Ti atom oxidation—XPS Ti 2p spectra show that the proportion of high-valence Ti (oxidized state) is significantly reduced after recombination, indicating that the FAPbI3 coating delays Ti3C2T oxidation. x Oxidative degradation of MXene in aqueous electrolytes. The high-temperature annealing process (drying at 160℃) of α-FAPbI3 itself creates a high-energy barrier, inhibiting the reversal to the δ phase.

[0031] Reason for this: The MXene coating layer acts as both a physical protective layer and an electron acceptor / donor buffer layer, simultaneously inhibiting the decomposition of FAPbI3 and the oxidation of MXene itself, thus achieving bidirectional stability enhancement.

[0032] Advantage 4: Significantly enhanced electronic conductivity overcomes the wide bandgap defect of FAPbI3.

[0033] Specific performance: DFT calculations show that the electronic state density near the Fermi level increases significantly after recombination, exhibiting metallic conductivity; EIS tests show the equivalent series resistance of the composite thin-film electrode (…). Rs It is lower than that of pure MXene.

[0034] Source technology: DFT theoretical calculation - Ti3C2T x The FAPbI3 heterojunction model confirms the redistribution of charge at the interface and the increase in the number of valence electrons in the conduction band of Pb atoms.

[0035] Cause of occurrence: Ti3C2T x The highly conductive network provides a fast electron transport channel for FAPbI3, compensating for the shortcomings of FAPbI3's semiconductor properties. Furthermore, the introduction of FAPbI3 also enhances the performance of Ti3C2T. x Longitudinal electron transport between layers; at the same time, the interface dipole effect reduces the electron injection barrier.

[0036] Advantage 5: The preparation process is simple, green, and low-cost, and has the potential for industrial scale-up.

[0037] Specifically, α-FAPbI3 is synthesized using a low-temperature solution method (≤160℃), eliminating the need for high-temperature sintering; the composite process involves only physical mixing, ultrasound, and vacuum filtration, without complex chemical modification.

[0038] Key technical points: High-purity α-FAPbI3 is prepared using a gradient temperature crystallization method (4℃ / h) without the need for toxic additives. Anhydrous ethanol is used as the dispersion solvent, making it environmentally friendly and easily recyclable.

[0039] Reasons for its existence: It avoids the high-temperature solid-state method or toxic solvents (such as DMF and DMSO) commonly used in traditional perovskite synthesis, thus reducing energy consumption and environmental pressure.

[0040] In summary, this invention innovatively proposes a two-way enhancement strategy of "coating stable perovskite with MXene and widening MXene through perovskite intercalation," successfully preparing Ti3C2T with high specific capacitance, ultralong cycle life, and high energy density. x The α-FAPbI3 composite thin film electrode not only solves the problem of the unstable application of halo perovskite FAPbI3 in the field of electrochemical energy storage, but also breaks through the technical bottleneck of interlayer stacking and surface oxidation of MXene materials. At the same time, it achieves bidirectional enhancement of the performance of the two materials, opening up a new technical path for the application of unstable halo perovskites in the field of electrochemical energy storage. Attached Figure Description

[0041] Figure 1 Pure Ti3C2T was prepared as a comparative example 1. x Thin films and Ti3C2T prepared in Examples 1-4 x XRD pattern of FAPbI3 composite thin film electrode; Figure 2 Ti3C2T prepared in Example 3x Digital photograph of the FAPbI3 composite thin film electrode; Figure 3 Ti3C2T prepared in Example 3 x CV curves of FAPbI3 composite thin film electrode at different scan rates; Figure 4 Ti3C2T prepared in Example 3 x GCD curves of FAPbI3 composite thin film electrode at different scan rates; Figure 5 Pure Ti3C2T was prepared as a comparative example 1. x Thin films and Ti3C2T prepared in Examples 1-4 x Comparison of specific capacitance of FAPbI3 composite thin film electrode under different current densities; Figure 6 The Ti3C2T based material obtained in Example 5 x GCD curves of Zn-ion supercapacitors with FAPbI3 composite thin film electrodes; Figure 7 The Ti3C2T based material obtained in Example 5 x / FAPbI3 composite thin film electrode Zn ion supercapacitor in 1Ag -1 Capacitance retention rate after 15,000 cycles under certain conditions. Detailed Implementation

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Example 1 Ti3C2T x The preparation method of the α-FAPbI3 composite thin film electrode material specifically includes the following steps: (1) Preparation of high-purity α-FAPbI3 powder Weigh 0.2264 g FAI and 0.5532 g PbI2, add them to 10 mL GVL solvent, stir at 60 °C for 12 h, and filter through a 0.22 μm filter membrane to obtain a clear precursor solution; place the precursor solution in a constant temperature environment of 60 °C, and program the temperature to 95 °C at a rate of 4 °C / h, and continue to crystallize for 24 h; wash the precipitated crystals with hot cyclohexane at 95 °C to remove residual precursor solution, filter, and dry in an oven at 160 °C for 2 h to obtain black α-FAPbI3 powder; (2) Few-layered Ti3C2Tx Preparation of nanosheets 1.6 g of LiF was slowly added to 20 mL of 12M HCl and stirred for 10 min. Then, 1 g of Ti3AlC2MAX phase powder was added, and the mixture was reacted in an oil bath at 50 °C for 24 h. The reaction mixture was centrifuged at 3500 rpm for 10 min, and the precipitate was washed twice with 1M HCl, followed by repeated washing with deionized water until the pH of the supernatant was approximately 6. The multilayer Ti3C2T was collected. x The precipitate was added to deionized water at a solid-liquid ratio of 1 g: 200 mL, and ultrasonically exfoliated at 200 W for 2 h. Then, manual shaking was used to assist exfoliation for 10 min. The mixture was centrifuged at 3500 rpm for 10 min, and the dark green supernatant was collected and freeze-dried for 72 h to obtain a few-layer Ti3C2T. x Nanosheets; (3) Ti3C2T x Preparation of α-FAPbI3 composite films Weigh out 50 mg of few-layer Ti3C2T x Nanosheet powder and 10 mg of α-FAPbI3 powder (mass ratio 5:1) were mixed and ground in a mortar for 10 min. 20 mL of anhydrous ethanol was added, and the mixture was sonicated at 200 W for 10 min. The dispersion was then filtered through a 0.064 μm porous polypropylene membrane under vacuum at -0.08 MPa until the membrane surface was dry. Finally, the resulting filter cake, along with the porous polypropylene membrane, was dried in a vacuum drying oven at 60 °C for 12 h. The membrane was then removed to obtain Ti3C2T. x / α-FAPbI3 composite thin film electrode material.

[0044] Example 2 The steps are basically the same as in Example 1, except that the amount of α-FAPbI3 powder added in step (3) is 20 mg (mass ratio 5:2). The resulting Ti3C2T x The specific capacitance of the α-FAPbI3 composite thin film electrode material is 475.57 F / g.

[0045] Example 3 The steps are basically the same as in Example 1, except that the amount of α-FAPbI3 powder added in step (3) is 30 mg (mass ratio 5:3).

[0046] Example 4 The steps are basically the same as in Example 1, except that the amount of α-FAPbI3 powder added in step (3) is 40 mg (mass ratio 5:4).

[0047] Example 5 Based on Ti3C2T xThe preparation method of the Zn ion supercapacitor with FAPbI3 composite thin film electrode specifically includes the following steps: (1) Dissolve 2.74 g ZnCl2 in 20 mL of a mixture of anhydrous ethanol and glycerol (volume ratio 4:1), stir until completely dissolved, seal and let stand for 24 h to obtain electrolyte; (2) Using zinc foil as the negative electrode, the Ti3C2T prepared in Example 3 was used. x The α-FAPbI3 composite thin-film electrode material is used as the positive electrode, and a CR2032 coin cell case is used to assemble Zn / / ZnCl2 / / Ti3C2T. x / FAPbI3 hybrid supercapacitor.

[0048] Comparative Example 1 Few-layer Ti3C2T was prepared according to step (2) of Example 1. x Nanosheets, without the addition of FAPbI3. Pure Ti3C2T was thus prepared. x The specific capacitance of the thin film is 281.86 F / g.

[0049] Performance testing 1. XRD characterization like Figure 1 As shown, the figure contains 6 XRD curves. Among them, the Ti3C2T prepared in Comparative Example 1... x The spectrum (black curve) shows a distinct (002) diffraction peak near 7.1°, while the other diffraction peaks almost disappear, indicating that the Al layer in the MAX phase has been successfully etched, and Ti3AlC2 has been completely transformed into Ti3C2T. x It was confirmed that Ti3C2T could be successfully obtained through in-situ HF etching with HCl / LiF and manual oscillation stripping method used in this study. x Thin slices.

[0050] The information for the remaining 5 curves is as follows: The red curve corresponds to the α-FAPbI3 powder obtained in step (1) of Example 1. It shows characteristic diffraction peaks belonging to the (100) and (200) crystal planes at 2θ = 14.2°±0.2° and 28.4°±0.2°, and does not show the characteristic peak of δ-FAPbI3 at 2θ = 11.8°±0.2°, indicating that the product is a pure α phase with no δ phase residue.

[0051] The blue curve corresponds to the Ti3C2T prepared in Example 1. x A composite film with a ratio of FAPbI3 = 1:5.

[0052] The green curve corresponds to the Ti3C2T prepared in Example 2. x A composite film with FAPbI3 = 2:5.

[0053] The purple curve corresponds to the Ti3C2T prepared in Example 3. x A composite film with FAPbI3 ratio of 3:5.

[0054] The yellow curve corresponds to the Ti3C2T prepared in Example 4. x A composite film with FAPbI3 ratio of 4:5.

[0055] The XRD patterns of the four composite films all showed characteristic diffraction peaks of α-FAPbI3 ((100) and (200) crystal planes) consistent with the red curve, and no characteristic peaks of δ-FAPbI3 were detected in any of them. This indicates that Ti3C2T with different mass ratios... x In the FAPbI3 composite film, FAPbI3 exists entirely as the pure α phase, without any δ phase impurities. (Ti3C2T) x It has been successfully complexed with α-FAPbI3.

[0056] 2. Electrochemical performance testing like Figure 2 As shown, the Ti3C2T prepared in Example 3... x The FAPbI3 composite thin film electrode was cut into discs with a diameter of 5 mm (mass loading of approximately 2 mg / cm). 2 The electrode used is 2M H2SO4 as the working electrode. A three-electrode system is adopted, with 2M H2SO4 as the electrolyte, activated carbon as the counter electrode, and H2SO4 as the reference electrode.

[0057] like Figure 3 As shown, the cyclic voltammetry (CV) curves of this composite thin-film electrode at different scan rates exhibit an approximately rectangular shape, and a pair of redox peaks (2~100 mV s) appear with changes in scan rate. -1 This proves that Faraday redox reactions occur in all acidic electrolytes, demonstrating the pseudocapacitive effect of MXene.

[0058] like Figure 4 As shown, the galvanostatic charge-discharge (GCD) curves of the composite thin film electrode at different scan rates all maintain a symmetrical triangular shape and have no obvious plateau, confirming that the redox reaction of the MXene electrode has good reversibility and typical pseudocapacitive characteristics.

[0059] like Figure 5 As shown, Comparative Example 1, pure Ti3C2T, is presented. x Ti3C2T with different mass ratios than Examples 1-4 x The curves show the comparison of the specific capacitance of the / FAPbI3 composite material under different current densities. As can be seen from the figure, the specific capacitance of all samples gradually decreases with increasing current density, but the specific capacitance of Ti3C2T... xThe rate of decrease in specific capacitance of the / FAPbI3 composite material is significantly slower than that of pure Ti3C2T. x Furthermore, the composite material with a mass ratio of 5:3 in Example 3 maintained the highest specific capacitance at all current densities, indicating that the rate performance of the composite material is significantly better than that of pure Ti3C2T. x At a current density of 1 A / g, the specific capacitance of the composite thin film electrode of this ratio reaches 583.0 F / g, which is a significant advantage compared with other embodiments and Comparative Example 1.

[0060] The above test results indicate that the charge storage of this composite thin film electrode is mainly achieved through surface pseudocapacitance.

[0061] 3. Device Testing like Figure 6 As shown, the GCD curve of the device prepared in Example 5 is a symmetrical triangle with no obvious charge-discharge plateau, which confirms that the zinc ion hybrid supercapacitor operates stably within the voltage window of 0~1.4 V and has typical pseudocapacitive characteristics.

[0062] like Figure 7 As shown, the device prepared in Example 5 is 1 A·g -1 After 15,000 charge-discharge cycles at a current density, it still retains 82.9% of its initial capacity, demonstrating excellent cycle stability. The energy density at a power density of 1339 μW / cm² is equivalent to 74.4 μWh / cm². 2 .

[0063] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A halide perovskite / MXene composite energy storage electrode material, characterized in that, The raw materials include the following parts by weight: 1-4 parts of halide perovskite and 5 parts of two-dimensional MXene.

2. The halide perovskite / MXene composite energy storage electrode material according to claim 1, characterized in that, The raw materials include the following parts by weight: 3 parts of halide perovskite and 5 parts of two-dimensional MXene.

3. The halide perovskite / MXene composite energy storage electrode material according to claim 1 or 2, characterized in that, The halide perovskite is high-purity α-FAPbI3.

4. The halide perovskite / MXene composite energy storage electrode material according to claim 3, characterized in that, The X-ray diffraction pattern of the high-purity α-FAPbI3 shows characteristic diffraction peaks at 2θ = 14.2° ± 0.2° and 28.4° ± 0.2° belonging to the (100) and (200) crystal planes, respectively, and there are no characteristic diffraction peaks belonging to δ-FAPbI3 at 2θ = 11.8° ± 0.2°.

5. A halide perovskite / MXene composite energy storage electrode material according to claim 1 or 2, characterized in that, The two-dimensional MXene is a few-layer Ti3C2T x Nanosheets, in which T x Represents a surface terminal functional group, including at least one of -F, -O and -OH.

6. A halide perovskite / MXene composite energy storage electrode material according to claim 1 or 2, characterized in that, The two-dimensional MXene coats the surface of the halide perovskite, forming a continuous conductive network structure, and some halide perovskite is embedded between the two-dimensional MXene layers, increasing its interlayer spacing.

7. A method for preparing the halide perovskite / MXene composite energy storage electrode material as described in claim 1, characterized in that, Specifically, the following steps are included: (1) Preparation of halide perovskite Formamidin hydroiodide was mixed with lead iodide, an organic solvent was added, the mixture was stirred, filtered, heated, crystallized, washed, filtered again, and dried to obtain black α-FAPbI3 powder. (2) Preparation of two-dimensional MXene Lithium fluoride was added to hydrochloric acid and stirred. MAX phase Ti3AlC2 powder was then added, and the mixture was reacted in an oil bath. After centrifugation, the precipitate was collected, washed, and water was added. The precipitate was then ultrasonically exfoliated, supplemented with manual oscillation exfoliation. After centrifugation again, the dark green supernatant was collected and freeze-dried to obtain a few-layer Ti3C2T. x Nanoparticle powder; (3) Preparation of halide perovskite / MXene composite energy storage electrode material Black α-FAPbI3 powder and few-layer Ti3C2T x Nanosheet powder is mixed and ground, a dispersing solvent is added, ultrasonic treatment is performed, and the mixture is deposited on a porous substrate. After filtration and vacuum drying, the membrane is peeled off to obtain the halide perovskite / MXene composite energy storage electrode material.

8. The method for preparing a halide perovskite / MXene composite energy storage electrode material according to claim 7, characterized in that, In step (1), the ratio of formamidinium hydroiodate, lead iodide, and organic solvent is 1 mmol : (0.95~1.05) mmol : (5~20) mL; the organic solvent is selected from at least one of γ-valerolactone, N,N-dimethylformamide, and dimethyl sulfoxide; the stirring temperature is 50~70℃, and the time is 6~24 h; the filtration device is a 0.22~0.45 μm filter membrane; the heating is specifically as follows: the precursor solution obtained after filtration is placed in a constant temperature environment of 50~70℃, and the temperature is programmed to rise to 90~100℃ at a heating rate of 2~10℃ / h; the crystallization time is 12~48 h; the cleaning reagent is hot cyclohexane at 80~100℃; the drying device is an oven at a temperature of 140~180℃ for 1~3 h; In step (2), the concentration of hydrochloric acid is 6-12 M; the ratio of lithium fluoride, hydrochloric acid, and MAX phase Ti3AlC2 powder is (1.5-2.0) g : 20 mL : 1 g; the reaction temperature in the oil bath is 40-60℃, and the time is 20-30 h; the centrifugation speed is 3000-4000 rpm, and the time is 5-15 min; the washing process specifically involves washing the precipitate with 1M HCl 1-3 times, followed by repeated washing with deionized water until the pH of the supernatant is ≥ 6; the solid-liquid ratio of water added is 1 g : (100-500) mL; the ultrasonic peeling power is 100-300 W, and the time is 1-4 h; the manual shaking peeling time is 5-15 min; the second centrifugation speed is 3000-4000 rpm, and the time is 5-15 min; the freeze-drying time is 48-96 h. In step (3), the black α-FAPbI3 powder and the few-layer Ti3C2T x The ratio of nanosheet powder to dispersing solvent is (10~40) mg : 50 mg : (10~50) mL; the mixing and grinding equipment is a mortar and pestle, and the time is 5~15 min; the dispersing solvent is selected from at least one of anhydrous ethanol, deionized water and isopropanol; the ultrasonic treatment power is 100~300 W, and the time is 5~30 min; the deposition equipment is a vacuum filtration device; the porous substrate is selected from nanoporous polypropylene membrane, polytetrafluoroethylene membrane or mixed cellulose ester membrane, with a pore size of 0.02~0.22 μm; the vacuum degree of the filtration is -0.1~-0.05 MPa; the vacuum drying equipment is a vacuum drying oven, the temperature is 50~80℃, and the time is 6~24 h.

9. The application of the halide perovskite / MXene composite energy storage electrode material as described in claim 1 in the preparation of supercapacitors.

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