Perovskite type sodium-ion battery negative electrode material for in-situ precipitation of nano high-entropy alloy and preparation method of perovskite type sodium-ion battery negative electrode material

Abstract

The invention discloses a perovskite type sodium-ion battery negative electrode material for in-situ precipitation of a nano high-entropy alloy and a preparation method of the perovskite type sodium-ion battery negative electrode material. The perovskite type sodium ion battery negative electrode material with the nano high-entropy alloy separated out in situ has the general formula of LaFex1Cux2Nix3Alx4Mnx5O3 at FeCuNiAlMn, x1 + x2 + x3 + x4 + x5 = 1, and FeCuNiAlMn is nano high-entropy alloy particles separated out on the surface of the negative electrode material. According to the method, in-situ component transformation of the nanoparticles on the surface of the perovskite matrix from Fe to FeCu to FeCuNiAlMn is achieved through the step-by-step thermal calcination process, meanwhile, the alloy particles are kept in the nanoscale size and evenly distributed, and precise control over the component performance of the nano high-entropy alloy particles is facilitated. The perovskite type negative electrode material prepared by the invention has a stable layered structure, volume expansion caused by intercalation and deintercalation of sodium ions can be effectively relieved, and the energy density of the negative electrode of the sodium ion battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery anode materials, and particularly to a perovskite-type sodium-ion battery anode material with in-situ precipitated nano-high-entropy alloy and a preparation method thereof. Background Art

[0002] Compared with lithium resources, sodium resources are rich in reserves and environmentally friendly, which can alleviate the problem of limited battery development caused by lithium resource shortage to a certain extent, so it is considered as a new generation of battery system to replace lithium-ion batteries. However, due to the larger radius of sodium ions than lithium ions, the ion diffusion rate is slower during the insertion-extraction cycle, which results in a large room for improvement in the energy density of sodium-ion batteries compared with lithium-ion batteries, hindering the application and popularization of sodium-ion batteries.

[0003] A sodium-ion battery consists of a positive electrode, a negative electrode, a separator, an electrolyte, a battery case, etc. At present, extensive research has been carried out on the positive electrode materials of sodium-ion batteries, but the research on the negative electrode materials of sodium-ion batteries is insufficient. The existing sodium-ion battery negative electrode material systems mainly focus on carbon-based materials, such as "A preparation method and application of a sodium-ion battery negative electrode material" disclosed in Patent No. CN119591080A, "An asphalt-based hard carbon negative electrode material with high initial efficiency, high rate performance and high capacity and a preparation method thereof" disclosed in Patent No. CN119601621A, and "A sodium-ion battery negative electrode material composed of bismuth oxychloride and sulfur-oxygen co-doped carbon quantum dots and a preparation method thereof" disclosed in Patent No. CN119143176B. These carbon-based materials have good cycle stability, but their specific capacity is low. Therefore, developing a new type of negative electrode material with high energy density and low cost and its preparation method is the key to realizing the commercial application of sodium-ion batteries. Summary of the Invention

[0004] To solve the problem of low specific capacity of the existing sodium-ion battery negative electrode materials, the present invention provides a perovskite-type sodium-ion battery negative electrode material with in-situ precipitated nano-high-entropy alloy, and its material general formula is LaFe x1 Cu x2 Ni x3 Al x4 Mn x5 O3@FeCuNiAlMn, where x1 + x2 + x3 + x4 + x5 = 1, and FeCuNiAlMn is nano-high-entropy alloy particles precipitated on the surface of the negative electrode material.

[0005] In addition, the present invention also provides a method for preparing the above-mentioned perovskite-type sodium-ion battery negative electrode material with in-situ precipitated nano-high-entropy alloy, including the following steps: S1: Completely dissolve La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 in deionized water, and stir well to obtain a homogeneous solution; S2: Stir the solution in a water bath, add citric acid until a viscous sol is obtained; S3: Dry the sol to obtain a xerogel, and then grind it to obtain a precursor powder; S4: Mix the precursor powder with a binder evenly, then put it into a mold and press it into a disc. Calcinate the disc in an air atmosphere to obtain a high-entropy perovskite oxide LaFe x1 Cu x2 Ni x3 Alx4Mn x5 O3, that is, intermediate product A; S5: Calcinate the intermediate product A disc at a high temperature in a CO / Ar mixed atmosphere to obtain a perovskite oxide LaFe with nano-Fe particles in-situ precipitated on the surface x1 Cu x2 Ni x3 Alx4Mn x5 O3@Fe, that is, intermediate product B; S6: Calcinate the intermediate product B disc at a medium temperature in a CO / Ar mixed atmosphere to obtain a perovskite oxide LaFe with nano-FeCu alloy particles in-situ precipitated on the surface x1 Cu x2 Ni x3 Alx4Mn x5 O3@FeCu, that is, intermediate product C; S7: Calcinate the intermediate product C disc at a low temperature in a CO / Ar mixed atmosphere to obtain a negative electrode material for a sodium-ion battery, that is, LaFe x1 Cu x2 Ni x3 Alx4Mn x5 O3@FeCuNiAlMn.

[0006] Preferably, the ratio of the total amount of substances of Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 to La(NO3)3 in step S1 is 1:1.

[0007] Preferably, in step S2, the water bath temperature is 60-80 °C and the stirring time is 4-6 h.

[0008] Preferably, in step S2, the molar ratio of citric acid to the total molar amount of Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 is 1:1.

[0009] Preferably, in step S3, the sol is dried by a blast dryer at a drying temperature of 100 - 200 °C for a drying time of 8 - 12 h.

[0010] Preferably, in step S4, the calcination temperature of the wafer is 500 - 600 °C, the calcination time is 3 - 6 h, and the heating rate and cooling rate are 4 - 6 °C / min.

[0011] Preferably, in step S5, the calcination temperature of the intermediate product A is 1000 - 1150 °C, the content of the CO / Ar mixed atmosphere is 5% - 10%, the calcination time is 1 - 2 h, the heating rate and cooling rate are 8 - 10 °C / min, and the heating and cooling processes are carried out in an Ar atmosphere.

[0012] Preferably, in step S6, the calcination temperature of the intermediate product B is 800 - 950 °C, the content of the CO / Ar mixed atmosphere is 5% - 10%, the calcination time is 1 - 2 h, the heating rate and cooling rate are 5 - 8 °C / min, and the heating and cooling processes are carried out in an Ar atmosphere.

[0013] Preferably, in step S7, the calcination temperature of the intermediate product C is 500 - 650 °C, the content of the CO / Ar mixed atmosphere is 5% - 10%, the calcination time is 1 - 2 h, the heating rate and cooling rate are 4 - 6 °C / min, and the heating and cooling processes are carried out in an Ar atmosphere.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention prepares a perovskite - type sodium - ion negative electrode material with in - situ precipitated nano - high - entropy alloy by the sol - gel method. The metal nitrate raw materials are cheap and easily available, the preparation process is simple and easy to control, and the reaction conditions are mild. (2) The perovskite - type negative electrode material prepared by the present invention has a stable layered structure, which can effectively alleviate the volume expansion caused by the insertion and extraction of sodium ions, and improve the energy density of the negative electrode of the sodium - ion battery. (3) The in - situ precipitated nano - high - entropy alloy particles prepared by the present invention are stably anchored on the surface of the perovskite matrix. Due to the high - entropy effect, the nano - particles have excellent structural stability and catalytic activity, which is beneficial to improving the conductivity and capacity retention rate of the negative electrode of the sodium - ion battery. (4) The present invention realizes the in-situ compositional transformation of nanoparticles on the surface of the perovskite matrix from Fe→FeCu→FeCuNiAlMn through a stepwise thermal calcination process, while keeping the alloy particles in nanoscale size and uniform distribution, which is beneficial to the precise control of the composition and properties of the nanoscale high-entropy alloy particles. Description of the Drawings

[0015] Figure 1 Schematic diagram of the preparation process for in-situ precipitated nanoscale high-entropy alloy particles on the surface of the perovskite-type matrix in Examples 1, 2, and 3 of the present invention; Figure 2 LaFe prepared in Example 1 of the present invention 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 Microstructure diagram of O3@FeCuNiAlMn; Figure 3 LaFe prepared in Example 1 of the present invention 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 O3 and LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 XRD diffraction pattern of O3@FeCuNiAlMn; Figure 4 Charge-discharge curve of the sodium-ion half cell prepared in Example 1 of the present invention. Detailed Description of the Invention

[0016] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0017] Example 1 S1: Weigh La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 accurately according to the stoichiometric ratio of the chemical formula LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 O3, then completely dissolve them in deionized water and stir well to obtain a homogeneous solution; S2: Stir the solution in a water bath at 80 °C for 6 h, and add citric acid until a viscous sol is obtained. The molar ratio of citric acid to the total molar amount of La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 is 1:1; S3: Dry the sol in a forced-air drying oven at 100 °C for 10 h to obtain a dry gel, and then grind it for 20 min to obtain a precursor powder; S4: Mix the precursor powder with a binder evenly, then put it into a mold and press it into a disc. Calcinate the disc in an air atmosphere at 500 °C for 5 h, and control the heating rate and cooling rate at 5 °C / min to obtain a high-entropy perovskite-type oxide LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 O3; S5: Calcinate the LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 O3 disc in a 10% CO / Ar mixed atmosphere at 1100 °C for 2 h, control the heating rate and cooling rate at 10 °C / min, and carry out the heating and cooling processes in an Ar atmosphere to obtain LaFe with nano-Fe particles in-situ precipitated on the surface 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 O3@Fe; S6: Calcinate the LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 O3@Fe disc in a 10% CO / Ar mixed atmosphere at 900 °C for 1 h, control the heating rate and cooling rate at 8 °C / min, and carry out the heating and cooling processes in an Ar atmosphere to obtain LaFe with nano-FeCu alloy particles in-situ precipitated on the surface 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 O3@FeCu; S7: The LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1The O3@FeCu wafer was calcined in a 10% CO / Ar mixed atmosphere at 500 °C for 2 h, with the heating rate and cooling rate controlled at 6 °C / min. The heating and cooling processes were carried out in an Ar atmosphere to obtain LaFe with nano-sized FeCuNiAlMn high-entropy alloy particles precipitated in-situ on the surface. 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 The O3@FeCuNiAlMn anode material for sodium-ion batteries.

[0018] Example 2 S1: La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 were accurately weighed according to the stoichiometric ratio of the chemical formula LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.2 Mn 0.2 O3, completely dissolved in deionized water, and stirred thoroughly to obtain a homogeneous solution. S2: The solution was stirred in a water bath at 70 °C for 5 h, and citric acid was added until a viscous sol was obtained. The molar ratio of citric acid to the total molar amount of La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 was 1:1. S3: The sol was placed in a forced-air drying oven at 200 °C and dried for 8 h to obtain a xerogel, which was then ground for 30 min to obtain a precursor powder. S4: The precursor powder was mixed uniformly with a binder, then placed in a mold and pressed into a wafer. The wafer was calcined in an air atmosphere at 600 °C for 4 h, with the heating rate and cooling rate controlled at 6 °C / min, to obtain a high-entropy perovskite-type oxide LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.2 Mn 0.2 O3. S5: The LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.2 Mn 0.2 O3 wafer was calcined in a 10% CO / Ar mixed atmosphere at 1000 °C for 1 h, with the heating rate and cooling rate controlled at 8 °C / min. The heating and cooling processes were carried out in an Ar atmosphere to obtain LaFe with nano-sized Fe particles precipitated in-situ on the surface. 0.2 Cu 0.2 Ni0.2 Al 0.2 Mn 0.2 O3@Fe; S6: Calcinate the LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.2 Mn 0.2 O3@Fe wafers in a 10% CO / Ar mixed atmosphere at 850 °C for 1.5 h, with the heating rate and cooling rate controlled at 10 °C / min, and the heating and cooling processes carried out in an Ar atmosphere, to obtain LaFe with nano-FeCu alloy particles in-situ precipitated on the surface 0.2 Cu 0.2 Ni 0.2 Al 0.2 Mn 0.2 O3@FeCu; S7: Calcinate the intermediate product C wafers in a 10% CO / Ar mixed atmosphere at 550 °C for 1 h, with the heating rate and cooling rate controlled at 6 °C / min, and the heating and cooling processes carried out in an Ar atmosphere, to obtain LaFe with nano-FeCuNiAlMn high-entropy alloy particles in-situ precipitated on the surface 0.2 Cu 0.2 Ni 0.2 Al 0.2 Mn 0.2 O3@FeCuNiAlMn anode material for sodium-ion batteries.

[0019] Example 3 S1: Weigh La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, Mn(NO3)2 accurately according to the stoichiometric ratio of the chemical formula LaFe 0.3 Cu 0.2 Ni 0.2 Al 0.1 Mn 0.2 O3, and then completely dissolve them in deionized water and stir well to obtain a homogeneous solution.

[0020] S2: Stir the solution in a water bath at 60 °C for 4 h, and add citric acid until a viscous sol is obtained. The molar ratio of citric acid to the total molar amount of La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, Mn(NO3)2 is 1:1.

[0021] S3: Put the sol into a forced-air drying oven at 100 °C and dry it for 8 h to obtain a xerogel, and then grind it for 15 min to obtain a precursor powder.

[0022] S4: Mix the precursor powder evenly with the binder, then put it into a mold and press it into a wafer. Calcinate the wafer in an air atmosphere at 500 °C for 3 h, and control the heating rate and cooling rate at 4 °C / min to obtain a high-entropy perovskite oxide LaFe 0.3 Cu 0.2 Ni 0.2 Al 0.1 Mn 0.2 O3.

[0023] S5: Calcinate the LaFe 0.3 Cu 0.2 Ni 0.2 Al 0.1 Mn 0.2 O3 wafer in a 5% CO / Ar mixed atmosphere at 1000 °C for 1 h. Control the heating rate and cooling rate at 8 °C / min, and carry out the heating and cooling processes in an Ar atmosphere to obtain LaFe 0.3 Cu 0.2 Ni 0.2 Al 0.1 Mn 0.2 O3@Fe.

[0024] S6: Calcinate the LaFe 0.3 Cu 0.2 Ni 0.2 Al 0.1 Mn 0.2 O3@Fe wafer in a 5% CO / Ar mixed atmosphere at 800 °C for 1 h. Control the heating rate and cooling rate at 5 °C / min, and carry out the heating and cooling processes in an Ar atmosphere to obtain LaFe 0.3 Cu 0.2 Ni 0.2 Al 0.1 Mn 0.2 O3@FeCu.

[0025] S7: Calcinate the LaFe 0.3 Cu 0.2 Ni 0.2 Al 0.1 Mn 0.2 O3@FeCu wafer in a 5% CO / Ar mixed atmosphere at 500 °C for 1 h. Control the heating rate and cooling rate at 4 °C / min, and carry out the heating and cooling processes in an Ar atmosphere to obtain LaFe 0.3 Cu 0.2 Ni 0.2 Al 0.1 Mn 0.2O3@FeCuNiAlMn anode material for sodium-ion batteries.

[0026] Comparative Example 1 S1: After accurately weighing La(NO3)3, Fe(NO3)3, and Cu(NO3)2 according to the stoichiometric ratio of the chemical formula LaFe 0.3 Cu 0.7 O3, it was completely dissolved in deionized water and stirred thoroughly to obtain a homogeneous solution.

[0027] S2: The solution was stirred in a water bath at 50 °C for 5 h, and citric acid was added until a viscous sol was obtained. The molar ratio of citric acid to the total molar amount of La(NO3)3, Fe(NO3)3, and Cu(NO3)2 was 1:1.

[0028] S3: The sol was placed in a forced-air drying oven at 100 °C and dried for 10 h to obtain a xerogel, which was then ground for 15 min to obtain a precursor.

[0029] S4: The precursor powder was mixed uniformly with a binder, then placed in a mold and pressed into a disc. The disc was calcined in an air atmosphere at 550 °C for 2 h, and the heating rate and cooling rate were controlled at 5 °C / min to obtain a high-entropy perovskite-type oxide LaFe 0.3 Cu 0.7 O3 with a single-phase structure.

[0030] S5: The LaFe 0.3 Cu 0.7 O3 disc was calcined in a 5% CO / Ar mixed atmosphere at 900 °C for 2 h, and the heating rate and cooling rate were controlled at 10 °C / min. The heating and cooling processes were carried out in an Ar atmosphere to obtain LaFe 0.3 Cu 0.7 O3@Fe with nano-Fe particles in-situ precipitated on the surface.

[0031] Comparative Example 2 S1: After accurately weighing La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 according to the stoichiometric ratio of the chemical formula LaFe 0.3 Cu 0.1 Ni 0.1 Al 0.1 Mn 0.1 O3, it was completely dissolved in deionized water and stirred thoroughly to obtain a homogeneous solution; S2: Stir the solution in a water bath at 70 °C for 6 h, and add citric acid until a viscous sol is obtained. The molar ratio of citric acid to the total molar amount of La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 is 1:1; S3: Dry the sol in a forced-air drying oven at 200 °C for 10 h to obtain a xerogel, and then grind it for 30 min to obtain a precursor powder; S4: Mix the precursor powder with a binder evenly, then put it into a mold and press it into a disc. Calcinate the disc in an air atmosphere at 600 °C for 3 h, and control the heating rate and cooling rate at 5 °C / min to obtain a high-entropy perovskite-type oxide LaFe 0.3 Cu 0.1 Ni 0.1 Al 0.1 Mn 0.1 O3; S5: Calcinate the LaFe 0.3 Cu 0.1 Ni 0.1 Al 0.1 Mn 0.1 O3 disc in a 10% CO / Ar mixed atmosphere at 1000 °C for 2 h, control the heating rate and cooling rate at 8 °C / min, and carry out the heating and cooling processes in an Ar atmosphere to obtain LaFe with nano-Fe particles in-situ precipitated on the surface [[ID=]27] 0.3 Cu 0.1 Ni 0.1 Al 0.1 Mn 0.1 O3@Fe; S6: Calcinate the LaFe 0.3 Cu 0.1 Ni 0.1 Al 0.1 Mn 0.1 O3@Fe disc in a 10% CO / Ar mixed atmosphere at 900 °C for 1 h, control the heating rate and cooling rate at 8 °C / min, and carry out the heating and cooling processes in an Ar atmosphere to obtain LaFe with nano-FeCu alloy particles in-situ precipitated on the surface 0.3 Cu 0.1 Ni 0.1 Al 0.1 Mn 0.1 O3@FeCu; S7: Calcinate the intermediate product C disc in a 10% CO / Ar mixed atmosphere at 600 °C for 1 h, control the heating rate and cooling rate at 6 °C / min, and carry out the heating and cooling processes in an Ar atmosphere to obtain LaFe with nano-FeCuNiAlMn high-entropy alloy particles in-situ precipitated on the surface0.3 Cu 0.1 Ni 0.1 Al 0.1 Mn 0.1 O3@FeCuNiAlMn anode material for sodium-ion batteries.

[0032] Comparative Example 3 S1: Weigh accurately La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 according to the stoichiometric ratio of the chemical formula LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.2 Mn 0.2 O3, and then completely dissolve them in deionized water and stir well to obtain a homogeneous solution; S2: Stir the solution in a water bath at 65 °C for 6 h, and add citric acid until a viscous sol is obtained. The molar ratio of citric acid to the total molar amount of La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 is 1:2; S3: Place the sol in a forced-air drying oven at 200 °C and dry it for 8 h to obtain a dry gel, and then grind it for 30 min to obtain a precursor powder; S4: Mix the precursor powder with a binder evenly, then put it into a mold and press it into a disc. Calcinate the disc in an air atmosphere at 600 °C for 4 h, and control the heating rate and cooling rate at 5 °C / min to obtain a high-entropy perovskite-type oxide LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.2 Mn 0.2 O3; S5: Calcinate the LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.2 Mn 0.2 O3 disc in a 10% CO / Ar mixed atmosphere at 1100 °C for 2 h, control the heating rate and cooling rate at 8 °C / min, and carry out the heating and cooling processes in an Ar atmosphere to obtain LaFe with nano-Fe particles in-situ precipitated on the surface 0.2 Cu 0.2 Ni 0.2 Al 0.2 Mn 0.2 O3@Fe; S6: Take LaFe 0.2 Cu 0.2 Ni 0.2Al 0.2 Mn 0.2 The LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.2 Mn 0.2 O3@FeCu wafers were calcined in a 10% CO / Ar mixed atmosphere at 900 °C for 2 h, with the heating rate and cooling rate controlled at 8 °C / min. The heating and cooling processes were carried out in an Ar atmosphere to obtain LaFe with nano-FeCu alloy particles in-situ precipitated on the surface S7: The intermediate product C wafers were calcined in a 10% CO / Ar mixed atmosphere at 600 °C for 1 h, with the heating rate and cooling rate controlled at 8 °C / min. The heating and cooling processes were carried out in an Ar atmosphere to obtain LaFe with nano-FeCuNiAlMn high-entropy alloy particles in-situ precipitated on the surface 0.2 Cu 0.2 Ni 0.2 Al 0.2 Mn 0.2 O3@FeCuNiAlMn anode material for sodium-ion batteries.

[0033] Comparative Example 4 S1: La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 were accurately weighed according to the stoichiometric ratio of the chemical formula LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 O3, and then completely dissolved in deionized water and stirred well to obtain a homogeneous solution; S2: The solution was stirred in a water bath at 80 °C for 6 h, and citric acid was added until a viscous sol was obtained. The molar ratio of citric acid to the total molar amount of La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 was 1:1; S3: The sol was dried in a forced-air drying oven at 150 °C for 10 h to obtain a xerogel, which was then ground for 20 min to obtain a precursor powder; S4: The precursor powder was mixed evenly with a binder, then placed in a mold and pressed into wafers. The wafers were calcined in an air atmosphere at 500 °C for 5 h, with the heating rate and cooling rate controlled at 5 °C / min, to obtain a high-entropy perovskite-type oxide LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 O3; S5: Calcine the LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 O3 wafer in a 10% CO / Ar mixed atmosphere at 1300 °C for 2 h, control the heating rate and cooling rate at 10 °C / min, and carry out the heating and cooling processes in an Ar atmosphere to obtain LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 O3@Fe; S6: Calcine the LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 O3@Fe wafer in a 10% CO / Ar mixed atmosphere at 1200 °C for 2 h, control the heating rate and cooling rate at 8 °C / min, and carry out the heating and cooling processes in an Ar atmosphere to obtain LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 O3@FeCu; S7: Calcine the LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 O3@FeCu wafer in a 10% CO / Ar mixed atmosphere at 900 °C for 2 h, control the heating rate and cooling rate at 6 °C / min, and carry out the heating and cooling processes in an Ar atmosphere to obtain LaFe 0.2 Cu 0.2 Ni 0.2 Al 0.3 Mn 0.1 O3@FeCuNiAlMn anode material for sodium-ion batteries.

[0034] Comparative Example 5 S1: Mix La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, Mn(NO3)2 according to the chemical formula LaFe 0.3 Cu 0.2 Ni 0.2 Al 0.1 Mn 0.2After accurately weighing the stoichiometric ratio of O3, it was completely dissolved in deionized water and stirred thoroughly to obtain a homogeneous solution.

[0035] S2: The solution was stirred in a water bath at 60 °C for 4 h, and citric acid was added until a viscous sol was obtained. The molar ratio of citric acid to the total molar amount of La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 was 1:1.

[0036] S3: The sol was placed in a forced-air drying oven at 200 °C and dried for 10 h to obtain a xerogel, which was then ground for 15 min to obtain the precursor powder.

[0037] S4: The precursor powder was mixed evenly with a binder and then pressed into a disc in a mold. The disc was calcined in an air atmosphere at 500 °C for 3 h, and the heating rate and cooling rate were controlled at 4 °C / min to obtain a high-entropy perovskite-type oxide LaFe 0.3 Cu 0.2 Ni 0.2 Al 0.1 Mn 0.2 O3.

[0038] S5: The LaFe 0.3 Cu 0.2 Ni 0.2 Al 0.1 Mn 0.2 O3 disc was calcined in a 5% CO / Ar mixed atmosphere at 1000 °C for 1 h, and the heating rate and cooling rate were controlled at 4 °C / min. The heating and cooling processes were carried out in an Ar atmosphere to obtain LaFe with nano-Fe particles in-situ precipitated on the surface 0.3 Cu 0.2 Ni 0.2 Al 0.1 Mn 0.2 O3@Fe.

[0039] S6: The LaFe 0.3 Cu 0.2 Ni 0.2 Al 0.1 Mn 0.2 O3@Fe disc was calcined in a 5% CO / Ar mixed atmosphere at 800 °C for 1 h, and the heating rate and cooling rate were controlled at 2 °C / min. The heating and cooling processes were carried out in an Ar atmosphere to obtain LaFe with nano-FeCu alloy particles in-situ precipitated on the surface 0.3 Cu 0.2 Ni 0.2 Al 0.1 Mn 0.2 O3@FeCu.

[0040] S7: Calcine the LaFe 0.3 Cu 0.2 Ni 0.2 Al 0.1 Mn 0.2 O3@FeCu wafer in a 5% CO / Ar mixed atmosphere at 500 °C for 1 h, controlling the heating rate and the cooling rate at 10 °C / min, and performing the heating and cooling processes in an Ar atmosphere to obtain LaFe with nano-sized FeCuNiAlMn high-entropy alloy particles precipitated in situ on the surface 0.3 Cu 0.2 Ni 0.2 Al 0.1 Mn 0.2 O3@FeCuNiAlMn anode material for sodium-ion batteries.

[0041] In the embodiments and comparative examples of the present invention, in step S4, the binder is phenolic resin, and the precursor powder and the binder are mixed in a ratio of 10:1.

[0042] Half-cell performance test method Grind 80 wt.% of the anode materials prepared in each of the examples and comparative examples, 13 wt.% of the conductive agent (CABOT BP2000), and 7 wt.% of the binder (PVDF) in a mortar for 40 min. After sieving, transfer them into a glass bottle, add NMP, and stir for 12 h to make a uniform fluid slurry. Then, coat the slurry on a carbon-coated Al foil, and then put it into an oven at 45 °C for baking for 0.5 h, transfer it into a vacuum drying oven, and dry it at 110 °C for 12 h. Finally, take out the electrode sheet and cut it into electrode wafers of appropriate size with a manual slicing machine. Using a sodium metal sheet as the counter electrode, 1 mol / L of NaClO4 dissolved in ethylene carbonate solution as the electrolyte, and a glass fiber GF / A as the separator, assemble it into a button half-cell in an argon glove box, and the charge and discharge performance of the battery is carried out at room temperature.

[0043] The half-cell performance test results are shown in Table 1.

[0044] Table 1 In the present invention, in Examples 1, 2, and 3, a three-step calcination process is adopted to gradually precipitate nano-sized FeCuNiAlMn high-entropy alloy particles on the surface of LaFe x1 Cu x2 Ni x3 Al x4 Mn x5 O3, as shown in Figure 1 shown. Among them, the high-temperature calcination at 1000 - 1150 °C in step S5 makes LaFe x1 Cux2 Ni x3 Al x4 Mn x5 The Fe atoms at the B-site in LaFeO3 precipitate out to form nano-sized Fe elemental particles on the surface, i.e., LaFe x1 Cu x2 Ni x3 Al x4 Mn x5 O3@Fe. The medium-temperature calcination at 800 - 950 °C in step S5 causes the Cu atoms at the B-site in LaFe x1 Cu x2 Ni x3 Al x4 Mn x5 O3@Fe to precipitate out, thus forming nano-sized FeCu alloy particles on the surface, i.e., LaFe x1 Cu x2 Ni x3 Al x4 Mn x5 O3@FeCu. The low-temperature calcination at 500 - 650 °C in step seven causes the Ni, Al, and Mn atoms at the B-site in LaFe x1 Cu x2 Ni x3 Al x4 Mn x5 O3@FeCu to also precipitate out, finally forming LaFe with nano-sized FeCuNiAlMn high-entropy alloy particles precipitated on the surface x1 Cu x2 Ni x3 Al x4 Mn x5 O3@FeCu@FeCuNiAlMn.

[0045] In Example 1, nano-sized FeCuNiAlMn high-entropy alloy particles with a size of 15 - 20 nm precipitate on the surface of LaFe 0.2 Cu 0.2 Ni 0.2 A l0.3 Mn 0.1 O3, as shown in Figure 2 shown. Figure 3 The XRD results of 0.2 Cu 0.2 Ni 0.2 A l0.3 Mn 0.1 O3@FeCuNiAlMn negative electrode material indicate that the precipitation of FeCuNiAlMn high-entropy alloy particles does not change the perovskite-type lattice structure of the substrate, which is beneficial to improving the charge-discharge cycle performance of the LaFe

[0046] Example 1 The charge-discharge specific capacity at a current density of 1C = 300 mA / g, the electrolyte is 1 mol / L NaClO4 dissolved in ethylene carbonate solution, and the charge-discharge cycle performance with a voltage window of 2.5 - 4.0 V is as Figure 4 shown. The half-cell performance test results of Example and Comparative Example 1 are shown in Table 1. Compared with Comparative Example 1, due to the precipitation of nano FeCuNiAlMn high-entropy alloy particles, its high-entropy effect has excellent structural stability and catalytic activity, and the first-cycle charge specific capacity, the first-cycle discharge specific capacity, and the first-cycle Coulomb efficiency are all significantly improved.

[0047] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. The negative electrode material of the perovskite-type sodium-ion battery for in-situ precipitation of nano high-entropy alloy, characterized in that, The general formula of its material is LaFe x1 Cu x2 Ni x3 Alx4Mn x5 O3@FeCuNiAlMn, where x1 + x2 + x3 + x4 + x5 = 1, and FeCuNiAlMn are nano high-entropy alloy particles precipitated on the surface of the negative electrode material.

2. Preparation method of perovskite-type sodium-ion battery anode material for in-situ precipitated nano high-entropy alloy, characterized in that, The method for preparing the perovskite-type sodium-ion battery anode material for in-situ precipitation of the nano high-entropy alloy described in claim 1 includes the following steps: S1: Completely dissolve La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 in deionized water, and fully stir to obtain a homogeneous solution; S2: Stir the solution in a water bath, add citric acid until a viscous sol is obtained; S3: Dry the sol to obtain a dry gel, and then grind it to obtain a precursor powder; S4: Mix the precursor powder evenly with the binder, then put it into a mold and press it into a wafer. Calcinate the wafer in an air atmosphere to obtain a high-entropy perovskite-type oxide LaFe x1 Cu x2 Ni x3 Alx4Mn x5 O3, namely the intermediate product A; S5: High-temperature calcine the intermediate product A wafer in a CO / Ar mixed atmosphere to obtain a perovskite-type oxide LaFe x1 Cu x2 Ni x3 Alx4Mn x5 O3@Fe, that is, intermediate product B; S6: The intermediate product B wafer is calcined at medium temperature in a CO / Ar mixed atmosphere to obtain a perovskite-type oxide LaFe x1 Cu x2 Ni x3 Alx4Mn x5 O3@FeCu, namely intermediate product C; S7: Calcinate the intermediate product C wafer at low temperature in a CO / Ar mixed atmosphere to obtain a perovskite-type sodium-ion battery anode material with nano FeCuNiAlMn high-entropy alloy particles in-situ precipitated on the surface, namely LaFe x1 Cu x2 Ni x3 Alx4Mn x5 O3@FeCuNiAlMn.

3. The preparation method of the perovskite-type sodium-ion battery anode material for in-situ precipitation of nano-high entropy alloy according to claim 2, characterized in that, In step S1, the ratio of the total amount of substances of Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 to La(NO3)3 is 1:

1.

4. The preparation method of the perovskite-type sodium-ion battery anode material for in-situ precipitation of nano-high entropy alloy according to claim 2, wherein, In step S2, the water bath temperature is 60-80 °C, and the stirring time is 4-6 h.

5. The preparation method of the perovskite-type sodium-ion battery anode material for in-situ precipitation of nano high-entropy alloy according to claim 2, characterized in that, In step S2, the ratio of the amount of substance of citric acid to the total amount of substances of La(NO3)3, Fe(NO3)3, Cu(NO3)2, Ni(NO3)2, Al(NO3)3, and Mn(NO3)2 is 1:

1.

6. The preparation method of the perovskite-type sodium-ion battery negative electrode material for in-situ precipitation of nano high-entropy alloy according to claim 2, characterized in that In step S3, the sol is dried by a blast dryer, the drying temperature is 100-200 °C, and the drying time is 8-12 h.

7. The preparation method of the perovskite-type sodium-ion battery negative electrode material for in-situ precipitation of nano high-entropy alloy according to claim 2, characterized in that, In step S4, the calcination temperature of the wafer is 500-600 °C, the calcination time is 3-6 h, and the heating rate and cooling rate are 4-6 °C / min.

8. The preparation method of the perovskite-type sodium-ion battery anode material for in-situ precipitation of nano high-entropy alloy according to claim 7, characterized in that In step S5, the calcination temperature of the intermediate product A is 1000-1150 °C, the content of the CO / Ar mixed atmosphere is 5%-10%, the calcination time is 1-2 h, the heating rate and cooling rate are 8-10 °C / min, and the heating and cooling processes are carried out in an Ar atmosphere.

9. The preparation method of the perovskite-type sodium-ion battery anode material for in-situ precipitation of nano high-entropy alloy according to claim 7, characterized in that, In step S6, the calcination temperature of the intermediate product B is 800-950 °C, the content of the CO / Ar mixed atmosphere is 5%-10%, the calcination time is 1-2 h, the heating rate and cooling rate are 5-8 °C / min, and the heating and cooling processes are carried out in an Ar atmosphere.

10. The preparation method of the perovskite-type sodium ion battery negative electrode material for in-situ precipitation of nano high-entropy alloy according to claim 9, characterized in that, In step S7, the calcination temperature of the intermediate product C is 500-650 °C, the content of the CO / Ar mixed atmosphere is 5%-10%, the calcination time is 1-2 h, the heating rate and cooling rate are 4-6 °C / min, and the heating and cooling processes are carried out in an Ar atmosphere.

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