Perovskite-based electrode material loaded with precious metal single atoms, preparation method and application of perovskite-based electrode material in supercapacitor

Abstract

The invention discloses a precious metal single atom-loaded perovskite-based electrode material, a preparation method and an application of the precious metal single atom-loaded perovskite-based electrode material in a supercapacitor. The electrode material is composed of precious metal single atoms and perovskite metal oxides, and has the advantages of high energy density, high power density, long cycle life and the like. The preparation method mainly comprises the following steps: synthesizing perovskite powder by using a sol-gel method or a solid phase method, preparing and dispersing a perovskite solution, preparing a precious metal dilute solution, reducing and loading precious metal single atoms, and finally performing rotary evaporation, baking and drying, collecting and ball-milling and the like. And stable loading of precious metal single atoms is realized by using anion defects existing on the surface of perovskite. Through the steps, the prepared perovskite-based electrode material loaded with the precious metal single atoms shows excellent energy density and rate capability when being used for a supercapacitor electrode, and can still keep good cycling stability and electrochemical performance especially under high current density.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage technology and relates to the preparation and application of electrode materials for supercapacitors. Specifically, it relates to a perovskite-based electrode material loaded with noble metal single atoms, its preparation method, and its application in supercapacitors. By introducing noble metal single atoms into the perovskite metal oxide matrix, the aim is to improve the conductivity, specific capacity, and rate performance of supercapacitors. Background Technology

[0002] With the booming development of the new energy industry, the importance of energy storage technology is becoming increasingly prominent. Among various emerging energy storage technologies, supercapacitors (SCs) have attracted widespread attention due to their advantages such as long cycle life, high safety, and high power density, demonstrating enormous application potential in the field of energy storage. SCs can be divided into two categories based on their energy storage mechanisms: Electrical Double-Layer Capacitors (EDLCs) and Pseudocapacitors. EDLCs primarily use carbon-based materials as electrodes, storing energy by forming a charge separation layer at the electrode / electrolyte interface. However, EDLCs suffer from low energy density due to their inherent physical adsorption characteristics, severely limiting their practical applications. In contrast, pseudocapacitors, because they can store charge not only through ion adsorption but also through near-surface redox reactions, possess greater specific capacitance and energy density. Therefore, the development of pseudocapacitor materials holds promise for solving the application problems of supercapacitors.

[0003] Researchers have conducted extensive studies on various metal oxide materials with pseudocapacitive properties. Among them, perovskite materials have become a research hotspot for supercapacitor electrode materials due to their stable crystal structure, abundant oxygen vacancies, high theoretical capacity, and highly reversible redox capabilities. However, perovskite oxides suffer from poor conductivity and low oxygen ion diffusion coefficient at room temperature, leading to difficulties in charge transfer during charge and discharge, resulting in actual capacities far lower than theoretical capacities. To overcome these limitations, researchers have employed various strategies, such as structural design to increase specific surface area and compositing with carbon materials to optimize conductivity, to optimize the electrochemical performance of these materials, but a qualitative improvement in performance has yet to be achieved.

[0004] In research on improving the performance of electrochemical energy storage materials, noble metals such as gold (Au), silver (Ag), and platinum (Pt) are often used to enhance the performance of these materials due to their excellent electrical conductivity and catalytic activity. However, the high cost of noble metals limits their widespread application. In recent years, single-atom materials (SAMs) have shown promise in addressing this issue due to their near 100% atomic utilization, excellent catalytic activity, and large specific surface area, enabling high catalytic activity with lower metal loading and reduced production costs. However, individual metal atoms, due to their high cohesive energy, tend to aggregate into nanoclusters, leading to a decrease in catalytic activity. Therefore, to obtain stable and highly dispersed metal atoms, it is usually necessary to load isolated metal atoms onto a support.

[0005] Against this backdrop, perovskites, rich in oxygen vacancies, serve as excellent carriers for anchoring noble metal single atoms. Conversely, the appropriate introduction of single atoms can promote the generation of oxygen vacancies, creating a mutually reinforcing relationship. Therefore, introducing noble metal single atoms into perovskite materials is expected to improve their electrical conductivity and promote surface redox reaction kinetics, thereby significantly enhancing the pseudocapacitive properties of perovskite materials. However, despite the enormous application potential of single-atom-loaded perovskite materials, effectively introducing noble metal single atoms and achieving uniform dispersion and stable loading on perovskite materials, as well as improving the electrochemical performance of perovskite-based supercapacitors through innovation in material design and synthesis techniques, remain pressing technical challenges. Summary of the Invention

[0006] (I) Purpose of the Invention

[0007] To address the shortcomings of existing perovskite-based supercapacitors, such as low perovskite conductivity, slow charge transport, and limited charge-discharge kinetics leading to energy densities far below theoretical performance and poor rate performance, this invention aims to provide a perovskite-based electrode material loaded with noble metal single atoms, its preparation method, and its application in supercapacitors. By loading noble metal single atoms into the anionic defect structure of perovskite material, the conductivity of the electrode material is significantly improved, and the number of electrochemical active sites is increased. This invention utilizes the inherent anionic defect structure of perovskite material as a loading matrix for noble metal single atoms. This not only fully leverages the excellent conductivity and catalytic activity of noble metal single atoms but also further optimizes the conductivity characteristics of perovskite oxides by introducing more oxygen holes, accelerating the redox reaction kinetics of charge storage, significantly improving the specific capacity and rate performance of the electrode material, and ultimately achieving a comprehensive improvement in the overall electrochemical performance of the supercapacitor.

[0008] (II) Technical Solution

[0009] To achieve the objective of this invention and solve its technical problems, the present invention adopts the following technical solution:

[0010] The first objective of this invention is to provide a perovskite-based electrode material loaded with noble metal single atoms, suitable for supercapacitors and used to improve their energy density and rate performance. Specifically:

[0011] The perovskite-based electrode material comprises a perovskite matrix and noble metal single atoms supported on the perovskite matrix, wherein: the perovskite matrix is ​​a single perovskite (ABO3), a double perovskite (A2BB'O6), or an RP-type perovskite (A... n+ 1B n O 3n+1 The perovskite matrix contains an A-site element selected from alkaline earth metals and transition metals, and a B-site element selected from transition metals. The perovskite matrix has an oxygen defect structure, either as a whole or on its surface, for loading the noble metal single atom.

[0012] The specific capacitance of the perovskite-based electrode material at a charge / discharge current of 1 A / g is 200-1450 F / g.

[0013] The second objective of this invention is to provide a method for preparing an electrode material, which includes the following steps:

[0014] SS1. Perovskite powder is synthesized using the sol-gel method or solid-phase method. The required amount of raw materials is determined according to the stoichiometry of the materials during the synthesis process. The formation and purity of perovskite crystals are ensured by controlling the temperature, stirring rate and reaction time during the synthesis process.

[0015] SS2. Take the perovskite powder synthesized in step SS1 and mix it with deionized water at a set mass ratio, and disperse it under ultrasonic conditions to obtain a uniformly dispersed perovskite solution.

[0016] SS3. Use inorganic compounds containing precious metal elements as raw materials, and prepare dilute solutions of precious metals by mixing them with deionized water at a set mass ratio;

[0017] SS4. Use a pipette to add the dilute noble metal solution prepared in step SS3 to the perovskite solution prepared in step SS2, and mix under stirring conditions to form a homogeneous mixture. Control the stirring speed and time to ensure the full adsorption and distribution of the noble metal elements.

[0018] SS5. Add the reducing agent solution dropwise to the mixture prepared in step SS4, and promote the reduction and loading of noble metal single atoms by controlling the addition rate of the reducing agent and the reaction temperature, so as to ensure that the noble metal single atoms are stably and uniformly attached to the surface or interior of the perovskite material.

[0019] SS6. The mixture prepared in step SS5 is subjected to rotary evaporation under vacuum conditions and a set temperature to remove excess solvent and obtain solid residue. By controlling the rotation speed, uniform evaporation is ensured so that noble metal single atoms are uniformly distributed in the perovskite structure.

[0020] SS7. The solid residue obtained in step SS6 is baked and dried under high temperature conditions. By controlling the temperature and drying time, the complete evaporation of moisture and organic solvents is ensured, and the loading state of noble metal single atoms is further stabilized to obtain perovskite oxide loaded with noble metal single atoms.

[0021] SS8. Collect the solid perovskite oxide obtained by baking and drying in step SS7, and ball mill it in a ball mill. By controlling the ball milling speed and time, obtain the perovskite-based electrode material with the required particle size loaded with noble metal single atoms.

[0022] The third objective of this invention is to provide a supercapacitor electrode, specifically, the supercapacitor electrode using the perovskite-based electrode material loaded with noble metal single atoms as described above as the positive electrode active material.

[0023] The fourth objective of this invention is to provide a supercapacitor, specifically, the electrodes of the supercapacitor are the supercapacitor electrodes described above in this invention.

[0024] (III) Technical Effects

[0025] Compared with the prior art, the perovskite-based electrode material loaded with noble metal single atoms, the preparation method, and the application of the present invention in supercapacitors have the following beneficial and significant technical effects:

[0026] (1) This invention uses perovskite as the active material, utilizing the inherent anionic defect structure of the material to load noble metal single atoms. Due to its large specific surface area, this material provides abundant electrochemical active sites and a large electrode / electrolyte interface contact area, which is beneficial for the diffusion of substances and the occurrence of chemical reactions at the interface. Furthermore, the noble metal single atoms, with their excellent conductivity, not only serve as active sites themselves but also introduce more oxygen holes, thereby effectively improving the conductivity of the perovskite oxide and accelerating the redox reaction kinetics of charge storage in the material. This significantly improves the electrochemical performance, thereby regulating the conductivity and catalytic activity of the material, resulting in higher specific capacity (greater than 1750 F / g) and superior rate performance.

[0027] (2) The perovskite-based electrode material of the present invention exhibits significant electrochemical performance in supercapacitors, including high specific capacitance and excellent rate performance. Due to the highly active catalytic effect of the noble metal single atoms in the material, the electrode material maintains good electrochemical stability and cycle life even at high current densities. Compared with traditional electrode materials, the electrode material of the present invention can achieve higher energy densities over a wider operating voltage range. In addition, the preparation method of the present invention is simple and controllable, enabling large-scale production at a lower cost. By optimizing the synthesis conditions, the consistency and stability of the material can be effectively improved, providing a reliable guarantee for practical applications. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of a perovskite metal oxide loaded with noble metal single atoms in this invention.

[0030] Figure 2 This is a flowchart illustrating the preparation process of the perovskite-based electrode material loaded with noble metal single atoms in this invention.

[0031] Figure 3 The figure shows the constant current charge-discharge curves of PNO and Pt-PNO at a current density of 1 A / g.

[0032] Figure 4 The figure shows the constant current charge-discharge curves of PNO and Pt-PNO at a current density of 10 A / g. Detailed Implementation

[0033] The materials involved in this invention include, but are not limited to, the materials in the following embodiments, and the preparation methods involved include, but are not limited to, the preparation methods used in the following examples. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those skilled in the art. The reagents or raw materials used in this invention can be obtained through conventional means. Unless otherwise specified, the reagents or raw materials used in this invention are used in accordance with conventional methods in the art or according to the product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the methods of this invention. The preferred embodiments and materials described in this invention are for illustrative purposes only. The invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0034] This invention aims to provide a perovskite-based electrode material loaded with noble metal single atoms, its preparation method, and its application in supercapacitors. By loading noble metal single atoms into the anionic defect structure of perovskite material, the conductivity of the electrode material is significantly improved and the number of electrochemical active sites is increased.

[0035] Example 1

[0036] As a specific example, such as Figure 1 As shown, the perovskite-based electrode material loaded with noble metal single atoms provided by this invention is suitable for supercapacitors and can be used to improve their energy density and rate performance. The perovskite-based electrode material comprises a perovskite matrix and noble metal single atoms loaded on the perovskite matrix, wherein the perovskite matrix is ​​a single perovskite (ABO3), a double perovskite (A2BB'O6), or an RP-type perovskite (A... n+1 B n O 3n+1 The perovskite matrix contains an A-site element selected from alkaline earth metals and transition metals, and a B-site element selected from transition metals. The perovskite matrix, either as a whole or on its surface, has an oxygen defect structure for loading noble metal single atoms. The specific capacitance of the perovskite-based electrode material at a charge / discharge current of 1 A / g is 200-1450 F / g. Preferably, the A-site element of the perovskite matrix includes one or any combination of two or more of sodium, potassium, calcium, strontium, cesium, barium, lanthanum, praseodymium, neodymium, samarium, gadolinium, dysprosium, holmium, erbium, and ytterbium; the B-site element includes one or any combination of two or more of scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, niobium, molybdenum, indium, and cerium; and the noble metal single atom element includes one or any combination of two or more of palladium, platinum, silver, gold, iridium, osmium, ruthenium, and rhodium.

[0037] Figure 2 The diagram shows a flowchart of the preparation process of the perovskite-based electrode material loaded with noble metal single atoms according to the present invention. Figure 2 As shown, the preparation method of the present invention mainly includes the following steps in practice:

[0038] SS1. Perovskite powder is synthesized using the sol-gel method or solid-phase method. The required amount of raw materials is determined according to the stoichiometry of the materials during the synthesis process. The formation and purity of perovskite crystals are ensured by controlling the temperature, stirring rate and reaction time during the synthesis process.

[0039] SS2. Take the perovskite powder synthesized in step SS1 and mix it with deionized water at a set mass ratio, and disperse it under ultrasonic conditions to obtain a uniformly dispersed perovskite solution.

[0040] SS3. Use inorganic compounds containing precious metal elements as raw materials, and prepare dilute solutions of precious metals by mixing them with deionized water at a set mass ratio;

[0041] SS4. Use a pipette to add the dilute noble metal solution prepared in step SS3 to the perovskite solution prepared in step SS2, and mix under stirring conditions to form a homogeneous mixture. Control the stirring speed and time to ensure the full adsorption and distribution of the noble metal elements.

[0042] SS5. Add the reducing agent solution dropwise to the mixture prepared in step SS4, and promote the reduction and loading of noble metal single atoms by controlling the addition rate of the reducing agent and the reaction temperature, so as to ensure that the noble metal single atoms are stably and uniformly attached to the surface or interior of the perovskite material.

[0043] SS6. The mixture prepared in step SS5 is subjected to rotary evaporation under vacuum conditions and a set temperature to remove excess solvent and obtain solid residue. By controlling the rotation speed, uniform evaporation is ensured so that noble metal single atoms are uniformly distributed in the perovskite structure.

[0044] SS7. The solid residue obtained in step SS6 is baked and dried under high temperature conditions. By controlling the temperature and drying time, the complete evaporation of moisture and organic solvents is ensured, and the loading state of noble metal single atoms is further stabilized to obtain perovskite oxide loaded with noble metal single atoms.

[0045] SS8. Collect the solid perovskite oxide obtained by baking and drying in step SS7, and ball mill it in a ball mill. By controlling the ball milling speed and time, obtain the perovskite-based electrode material with the required particle size loaded with noble metal single atoms.

[0046] In some preferred embodiments, in step SS1 above, perovskite powder is synthesized using a sol-gel method, wherein the perovskite is mono-perovskite (ABO3), bis-perovskite (A2BB'O6), or RP-type perovskite (A... n+1 B n O 3n+1The perovskite powder synthesis process includes at least the following sub-steps:

[0047] SS11. Weigh the metal nitrates of the A-site element and the B-site metal element according to the stoichiometric ratio, dissolve them in dilute nitric acid, heat the resulting solution to 40-60℃, and stir magnetically for 30-60 minutes to ensure the full dissolution and uniform distribution of metal ions.

[0048] SS12. Add CA (citric acid) and EDTA (ethylenediaminetetraacetic acid) to the solution obtained in sub-step SS11 according to the stoichiometric ratio to form a complex. After the complex is formed, heat at 20-200℃ and continue stirring for 1-10 hours until the sol spontaneously combusts. Remove the organic components through the self-heating reaction to obtain the preliminary inorganic residue, i.e., the perovskite precursor.

[0049] SS13. Calcine the perovskite precursor obtained in sub-step SS12 at a temperature of 900-1100℃ for 5-10 hours, while maintaining an air atmosphere during calcination to promote the formation and crystallization of oxides. After calcination, cool to room temperature and grind to obtain the desired perovskite powder.

[0050] In some preferred embodiments, in step SS2 above, the mass ratio of perovskite powder to deionized water is 1:9-50, and the solution is ultrasonically treated at a frequency of 20-40kHz for 1-3 hours to obtain a uniformly dispersed perovskite solution.

[0051] In some preferred embodiments, in step SS3 above, the inorganic compound containing the noble metal element is at least one of chloroplatinic acid, silver nitrate, tetrachloroauric acid, potassium chloropalladium, chloroiridium, potassium hexachloroosmium tetroxide, and potassium hexachlororuthenate, and the concentration of the dilute noble metal solution is 0.02-0.10 mol / L.

[0052] In some preferred embodiments, in step SS4 above, a dilute solution of precious metal is added dropwise to the perovskite solution and stirred at a speed of 300-600 rpm for 1-2 hours to form a homogeneous mixture, so as to ensure the full adsorption and distribution of precious metal elements.

[0053] In some preferred embodiments, in step SS5 above, the reducing agent is selected from at least one of anhydrous ethanol or 6wt% hydrogen peroxide solution, the addition rate is controlled at 0.2-1 mL / min, and the reaction is carried out under inert gas protection to promote the reduction and loading of noble metal single atoms.

[0054] In some preferred embodiments, in step SS6 above, rotary evaporation is carried out under a vacuum of 10-50 mbar, with the temperature controlled at 50-60°C and the rotation speed controlled at 60-120 rpm to ensure uniform evaporation, remove excess solvent, and obtain solid residue.

[0055] In some preferred embodiments, in step SS7 above, the solid residue is baked and dried at high temperature (80-120°C) for 5-20 hours under an inert gas atmosphere to ensure complete evaporation of moisture and organic solvents.

[0056] Furthermore, the present invention also provides an electrode for a supercapacitor, the electrode comprising the perovskite active material prepared by the present invention above, a conductive agent, and a binder, wherein the weight ratio of the electrode material to the conductive agent to the binder is 6-8:1-3:0.5-1; optionally, the binder comprises at least one of polytetrafluoroethylene (PTFE) and PVDF (polyvinylidene fluoride).

[0057] Furthermore, the present invention also provides a supercapacitor, wherein the electrodes of the supercapacitor are the electrodes described above. The supercapacitor can be a symmetrical supercapacitor (with the anode as the electrode) or an asymmetrical supercapacitor (with the anode being an activated carbon electrode). The electrolyte of the supercapacitor is at least one of LiOH, NaOH, and KOH aqueous solutions, and the concentration of the electrolyte is 0.1-10 mol / L.

[0058] Example 2

[0059] Based on Example 1 above, as a more specific example, Example 2 further details the preparation method of the perovskite-based electrode material loaded with noble metal single atoms according to the present invention. Specifically, the preparation method mainly includes the following steps:

[0060] (1) Synthesis of Ruddlesden-Popper (RP) type perovskite (A n+1 B n O 3n+1 A is an alkaline earth or rare earth element, and B is a transition metal element, with Pr4Ni3O as an example. 10 (PNO) as an example. Take 8.7g of praseodymium nitrate (analytical grade) and 5.8g of nickel nitrate (analytical grade), dissolve them in 50mL of dilute nitric acid, and then follow the formula CA:EDTA:Metal ions(Pr 3+ and Ni δ+ Weigh and add EDTA and CA in a ratio of 1.5:1:1, heat and stir to form a gel until it spontaneously combusts, the reaction time is 1.0-10.0 h, and the temperature is 20-200℃.

[0061] (2) The obtained precursor is calcined in air at a temperature of 900-1100℃ for 5-10 hours to obtain a single-atom support, denoted as PNO.

[0062] (3) Mix PNO powder with deionized water at a mass ratio of 2:20, and then sonicate in an ultrasonic machine for 2-3 hours to obtain a uniformly dispersed PNO solution for later use.

[0063] (4) Prepare a 0.05 mol / L chloroplatinic acid solution with chloroplatinic acid and deionized water for later use.

[0064] (5) Add the chloroplatinic acid solution obtained in step (4) to the PNO aqueous solution using a pipette while stirring. (6) Add anhydrous ethanol dropwise to the mixture obtained in step (5) while stirring.

[0065] (7) The mixed solution obtained in step (6) was rotary evaporated under vacuum at 55°C. The resulting solid was dried in an oven at 80°C for 12 hours.

[0066] (8) The obtained solid is collected and ball-milled to obtain PNO oxide loaded with Pt atoms, denoted as Pt-PNO.

[0067] After preparing the Pt-PNO perovskite-based electrode material, its electrochemical performance was tested using a three-electrode system and an electrochemical workstation. First, the prepared Pt-PNO electrode active material, PTFE, and Super P carbon were mixed in a mass ratio of 8:1:1, and an appropriate amount of anhydrous ethanol was added and stirred into a paste. After forming a film, it was cut into 1cm × 1cm sheets and vacuum dried at 60℃ for 5-10 hours. After drying, the film was pressed between two sheets of nickel foam as the working electrode. Then, the three-electrode system was subjected to charge-discharge cycle tests using an electrochemical workstation. In the three-electrode system, the Hg / HgO electrode served as the reference electrode, the platinum sheet electrode as the counter electrode, and 6M KOH solution as the electrolyte.

[0068] Figure 3 and Figure 4The figures show the galvanostatic charge-discharge curves of PNO and Pt-PNO at current densities of 1 A / g and 10 A / g, respectively. Using the formula C = Q / V, the specific capacitances of PNO and Pt-PNO at 1 A / g are calculated to be 552.2 F / g and 1774 F / g, respectively, and at 10 A / g, respectively, they are 137 F / g and 600 F / g. Furthermore, the figures show that the Pt-PNO sample exhibits significantly better electrochemical performance than the PNO sample throughout the charge-discharge process. Specifically, the charge-discharge curve of the Pt-PNO electrode material is more stable, with slower voltage decay, indicating a higher capacitance retention rate. In contrast, the charge-discharge curve of the PNO electrode material shows earlier voltage decay and a significantly shorter charge-discharge time than Pt-PNO, indicating that the specific capacitance and rate performance of PNO are lower than those of Pt-PNO. This shows that Pt-PNO exhibits higher capacity and better rate performance compared to PNO without Pt atoms. This result further proves that loading noble metal single atoms can effectively improve the electrochemical performance of perovskite oxide materials, making Pt-PNO an ideal choice for high-performance supercapacitor electrode materials.

[0069] Example 3

[0070] Based on the above Example 1, as a more specific example, Example 3 further details another method for preparing metal single atoms and perovskite according to the present invention. It is the same as Example 2, except that: chloroplatinic acid in steps (4) and (5) is replaced with silver nitrate, and anhydrous ethanol in step (6) is replaced with 6wt% H2O2 solution.

[0071] Example 4

[0072] Based on the above Example 1, as a more specific example, Example 4 further details another method for preparing metal single atoms and perovskite according to the present invention. It is the same as Example 2, except that: chloroplatinic acid in steps (4) and (5) is replaced with tetrachloroauric acid, and anhydrous ethanol in step (6) is replaced with 6wt% H2O2 solution.

[0073] Example 5

[0074] Based on the above Example 1, as a more specific example, Example 5 further details another method for preparing metal single atoms and perovskite according to the present invention. It is the same as Example 2, except that: chloroplatinic acid in steps (4) and (5) is replaced with potassium chloropalladate, and anhydrous ethanol in step (6) is replaced with 6wt% H2O2 solution.

[0075] Example 6

[0076] Based on the above Example 1, as a more specific example, Example 6 further details another method for preparing metal single atoms and perovskite according to the present invention. It is the same as Example 2, except that: chloroplatinic acid in steps (4) and (5) is replaced with chloroiridium acid, and anhydrous ethanol in step (6) is replaced with 6wt% H2O2 solution.

[0077] Example 7

[0078] Based on the above Example 1, as a more specific example, Example 7 further details another method for preparing metal single atoms and perovskite according to the present invention. It is the same as Example 2, except that: chloroplatinic acid in steps (4) and (5) is replaced with potassium hexachloroosmium tetroxide, and anhydrous ethanol in step (6) is replaced with 6wt% H2O2 solution.

[0079] Example 8

[0080] Based on the above Example 1, as a more specific example, Example 8 further details another method for preparing metal single atoms and perovskite according to the present invention. It is the same as Example 2, except that: chloroplatinic acid in steps (4) and (5) is replaced with potassium hexachlororuthenate, and anhydrous ethanol in step (6) is replaced with 6wt% H2O2 solution.

[0081] Example 9

[0082] Based on the above Example 1, as a more specific example, Example 9 further details another method for preparing metal single atoms and perovskite according to the present invention. It is the same as Example 2, except that: chloroplatinic acid in steps (4) and (5) is replaced with potassium hexachlororhodium, and anhydrous ethanol in step (6) is replaced with 6wt% H2O2 solution.

[0083] Example 10

[0084] Based on Example 1 above, as a more specific example, Example 10 further details another method for preparing metal single atoms and perovskite according to the present invention. Similar to Example 2, the difference lies in that: the Ruddlesden-Popper (RP) type perovskite (A...) in step (1) is... n+1 B n O 3n+1 Replace with monoperovskite (ABO3).

[0085] Example 11

[0086] Based on Example 1 above, as a more specific example, Example 11 further details another method for preparing metal single atoms and perovskite according to the present invention. Similar to Example 2, the difference lies in that: the Ruddlesden-Popper (RP) type perovskite (A...) in step (1) is... n+1 B n O 3n+1 Replace with double perovskite (A2BB'O6).

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A perovskite-based electrode material loaded with noble metal single atoms, suitable for supercapacitors and used to improve their energy density and rate performance, characterized in that: The perovskite-based electrode material comprises a perovskite matrix and noble metal single atoms supported on the perovskite matrix, wherein: the perovskite matrix is ​​a single perovskite (ABO3), a double perovskite (A2BB'O6), or an RP-type perovskite (A... n+1 B n O 3n+1 The perovskite matrix contains an A-site element selected from alkaline earth metals and transition metals, and a B-site element selected from transition metals. The perovskite matrix has an oxygen defect structure, either as a whole or on its surface, for loading the noble metal single atom. The specific capacitance of the perovskite-based electrode material at a charge / discharge current of 1 A / g is 200-1450 F / g.

2. The perovskite-based electrode material loaded with noble metal single atoms according to claim 1, characterized in that, The A-site element of the perovskite matrix includes one or any combination of two or more of sodium, potassium, calcium, strontium, cesium, barium, lanthanum, praseodymium, neodymium, samarium, gadolinium, dysprosium, holmium, erbium, and ytterbium; the B-site element includes one or any combination of two or more of scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, niobium, molybdenum, indium, and cerium; and the noble metal monatomic element includes one or any combination of two or more of palladium, platinum, silver, gold, iridium, osmium, ruthenium, and rhodium.

3. A method for preparing an electrode material, used to prepare the perovskite-based electrode material loaded with noble metal single atoms as described in claim 1 or 2, characterized in that, The method includes the following steps: SS1. Perovskite powder is synthesized using the sol-gel method or solid-phase method. The required amount of raw materials is determined according to the stoichiometry of the materials during the synthesis process. The formation and purity of perovskite crystals are ensured by controlling the temperature, stirring rate and reaction time during the synthesis process. SS2. Take the perovskite powder synthesized in step SS1 and mix it with deionized water at a set mass ratio, and disperse it under ultrasonic conditions to obtain a uniformly dispersed perovskite solution. SS3. Use inorganic compounds containing precious metal elements as raw materials, and prepare dilute solutions of precious metals by mixing them with deionized water at a set mass ratio; SS4. Use a pipette to add the dilute noble metal solution prepared in step SS3 to the perovskite solution prepared in step SS2, and mix under stirring conditions to form a homogeneous mixture. Control the stirring speed and time to ensure the full adsorption and distribution of the noble metal elements. SS5. Add the reducing agent solution dropwise to the mixture prepared in step SS4, and promote the reduction and loading of noble metal single atoms by controlling the addition rate of the reducing agent and the reaction temperature, so as to ensure that the noble metal single atoms are stably and uniformly attached to the surface or interior of the perovskite material. SS6. The mixture prepared in step SS5 is subjected to rotary evaporation under vacuum conditions and a set temperature to remove excess solvent and obtain solid residue. By controlling the rotation speed, uniform evaporation is ensured so that noble metal single atoms are uniformly distributed in the perovskite structure. SS7. The solid residue obtained in step SS6 is baked and dried under high temperature conditions. By controlling the temperature and drying time, the complete evaporation of moisture and organic solvents is ensured, and the loading state of noble metal single atoms is further stabilized to obtain perovskite oxide loaded with noble metal single atoms. SS8. Collect the solid perovskite oxide obtained by baking and drying in step SS7, and ball mill it in a ball mill. By controlling the ball milling speed and time, obtain the perovskite-based electrode material with the required particle size loaded with noble metal single atoms.

4. The method for preparing the electrode material according to claim 3, characterized in that, In step SS1 above, perovskite powder is synthesized using the sol-gel method, wherein the perovskite is mono-perovskite (ABO3), bis-perovskite (A2BB'O6), or RP-type perovskite (A... n+1 B n O 3n+1 The perovskite powder synthesis process includes at least the following sub-steps: SS11. Weigh the metal nitrates of the A-site element and the B-site metal element according to the stoichiometric ratio, dissolve them in dilute nitric acid, heat the resulting solution to 40-60℃, and stir magnetically for 30-60 minutes to ensure the full dissolution and uniform distribution of metal ions. SS12. Add CA (citric acid) and EDTA (ethylenediaminetetraacetic acid) to the solution obtained in sub-step SS11 according to the stoichiometric ratio to form a complex. After the complex is formed, heat at 20-200℃ and continue stirring for 1-10 hours until the sol spontaneously combusts. Remove the organic components through the self-heating reaction to obtain the preliminary inorganic residue, i.e., the perovskite precursor. SS13. Calcine the perovskite precursor obtained in sub-step SS12 at a temperature of 900-1100℃ for 5-10 hours, while maintaining an air atmosphere during calcination to promote the formation and crystallization of oxides. After calcination, cool to room temperature and grind to obtain the desired perovskite powder.

5. The method for preparing the electrode material according to claim 3, characterized in that, In step SS2 above, the mass ratio of perovskite powder to deionized water is 1:9-50, and the solution is ultrasonically treated at a frequency of 20-40 kHz for 1-3 hours to obtain a uniformly dispersed perovskite solution. In step SS3 above, the inorganic compound containing the noble metal element is at least one of chloroplatinic acid, silver nitrate, tetrachloroauric acid, potassium chloropalladium, chloroiridium, potassium hexachloroosmium tetroxide, and potassium hexachlororuthenate, and the concentration of the dilute noble metal solution is 0.02-0.10 mol / L. In step SS4 above, the dilute noble metal solution is added dropwise to the perovskite solution, and the mixture is stirred at a speed of 300-600 rpm for 1-2 hours to form a uniform mixture to ensure sufficient adsorption and distribution of the noble metal element. In step SS5 above, the reducing agent is at least one of anhydrous ethanol or 6 wt% hydrogen peroxide solution, the addition rate is controlled at 0.2-1 mL / min, and the reaction is carried out under inert gas protection to promote the reduction and loading of noble metal single atoms.

6. The method for preparing the electrode material according to claim 3, characterized in that, In step SS6 above, rotary evaporation is carried out under vacuum conditions of 10-50 mbar, with the temperature controlled at 50-60℃ and the rotation speed controlled at 60-120 rpm to ensure uniform evaporation, remove excess solvent, and obtain solid residue. In step SS7 above, the solid residue is baked and dried under high temperature conditions of 80-120℃ for 5-20 hours in an inert gas atmosphere.

7. A supercapacitor electrode, characterized in that, The supercapacitor electrode uses the perovskite-based electrode material loaded with noble metal single atoms as described in claim 1 or 2 as the positive electrode active material.

8. The supercapacitor electrode according to claim 7, characterized in that, The supercapacitor electrode comprises a perovskite-based electrode material, a conductive agent, and a binder, wherein the weight ratio of the electrode material to the conductive agent to the binder is 6-8:1-3:0.5-1; the binder is at least one of polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF).

9. A supercapacitor, characterized in that, The electrodes of the supercapacitor are those described in claim 8.

10. The supercapacitor electrode according to claim 9, characterized in that, The supercapacitor is a symmetrical supercapacitor with its anode being an electrode; or the supercapacitor is an asymmetrical supercapacitor with its anode being an activated carbon electrode; the electrolyte of the supercapacitor is at least one of LiOH, NaOH, and KOH aqueous solutions, and the concentration of the electrolyte is 0.1-10 mol / L.

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