Preparation method of high-entropy doped iron-based selenide material and application thereof

Abstract

The application relates to the technical field of sodium ion batteries, in particular to a preparation method and application of a high-entropy doped iron-based selenide material. The preparation method of the iron-based selenide is as follows: iron powder, selenium powder and multiple doped powders are subjected to ball milling treatment, and then calcination treatment is carried out to obtain the high-entropy doped iron-based selenide material. The iron-based selenide is endowed with excellent conductivity through high-entropy doping, the rate performance of the iron-based selenide material as a battery negative electrode is increased, and a large number of lattice defects can be introduced through high-entropy doping, so that the stability of the structure of the iron-based selenide material is improved, meanwhile, the preparation method has the characteristics of high selenium powder utilization rate, solvent-free and short time consumption. When the high-entropy doped iron-based selenide material prepared by the application is used as a sodium ion battery negative electrode material, the electrode pulverization and deactivation caused by the volume expansion of the metal selenide electrode material during the charging and discharging process can be effectively relieved, so that the sodium ion battery has better battery cycle performance.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, specifically to a method for preparing and applying high-entropy doped iron-based selenide materials. Background Technology

[0002] Currently, lithium-ion batteries are the most widely used and have the best overall performance among power batteries. However, with the continuous expansion of their applications, lithium resource shortages, high costs, and poor safety performance have become major obstacles to their use. Compared to lithium, sodium is abundant, inexpensive, and environmentally friendly, and it shares similar physical and chemical properties with lithium. Sodium-ion batteries operate on a similar principle to lithium-ion batteries, utilizing the insertion and extraction of sodium ions between the positive and negative electrodes to achieve charging and discharging. Therefore, they are an excellent potential alternative to lithium-ion batteries.

[0003] However, sodium-ion battery electrode materials still face several challenges. Sodium ions have a larger radius than lithium ions, resulting in slower diffusion kinetics within the electrode material, leading to capacity reduction and poor rate performance. Furthermore, the preparation and production of electrode materials often involve complex processes, significant environmental pollution, and low raw material utilization, resulting in substantial waste and failing to meet the continuously growing industrial demands. Metal selenides, with their high specific capacity, are ideal candidates for anode materials, possessing advantages such as chemical stability, environmental friendliness, and high theoretical mass and volumetric specific capacities. However, when selenides are used as anode materials, the insertion / extraction of sodium ions is often accompanied by significant volume changes, severely damaging the SEI film structure and causing a rapid decline in the capacity and cycle performance of sodium-ion batteries, rendering them unusable. Additionally, the preparation process of metal selenides often uses large amounts of organic solvents and excess selenium powder, resulting in complex processes that increase production cycles and costs, contradicting green environmental protection principles. Therefore, there is a need to develop a selenide anode material with a simple preparation process that can effectively improve the cycle performance of sodium-ion batteries. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a method for preparing high-entropy doped iron-based selenide materials, thereby improving the conductivity and stability of iron-based selenides through high-entropy doping. When used as a negative electrode material in sodium-ion batteries, this high-entropy doped iron-based selenide material can effectively alleviate electrode pulverization and deactivation caused by volume expansion of metal selenide electrode materials during charge and discharge processes, resulting in better battery cycle performance in sodium-ion batteries.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This invention provides a method for preparing high-entropy doped iron-based selenide materials. Under a protective atmosphere, iron powder, selenium powder and elemental powder are first ball-milled and mixed, and then calcined at 500-650°C to obtain high-entropy doped iron-based selenide materials.

[0007] Preferably, the elemental powder is one or more of nickel powder, chromium powder, copper powder, manganese powder, molybdenum powder, tungsten powder, and silicon powder.

[0008] More preferably, the elemental powder is any five combinations selected from nickel powder, chromium powder, copper powder, manganese powder, molybdenum powder, tungsten powder, and silicon powder.

[0009] Preferably, the molar ratio of the elements in the selenium powder, iron powder and elemental powder is 200:(80-120):(8-15).

[0010] Preferably, the protective atmosphere is a nitrogen atmosphere.

[0011] Preferably, the calcination treatment involves heating to 500–650°C at a heating rate of 5°C / min and calcining at that temperature for 3–4 hours.

[0012] Preferably, the ball milling time is 1 to 3 hours, and the ball milling oscillation frequency is set to 1800 rpm.

[0013] The present invention also provides a sodium-ion battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte. The negative electrode comprises a negative electrode current collector and a negative electrode material layer coated on the negative electrode current collector. The negative electrode material layer comprises the aforementioned high-entropy doped iron-based selenide material.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] This invention provides a method for preparing high-entropy doped iron-based selenide materials. The method involves ball milling iron powder, selenium powder, and various doping powders, followed by calcination. This invention imparts superior conductivity to iron-based selenides through high-entropy doping, increasing the rate performance of iron-based selenide materials as battery anodes. Simultaneously, high-entropy doping introduces numerous lattice defects, thereby improving the structural stability of the iron-based selenide material. Furthermore, the preparation method of this invention features high selenium powder utilization, environmental friendliness, and short processing time. No solvents are required throughout the process, and both ball milling and calcination techniques are easily scaled up for industrial production. The high-entropy doped iron-based selenide material prepared by this invention, when used as an anode material for sodium-ion batteries, not only effectively alleviates electrode pulverization and deactivation caused by volume expansion of metal selenide electrode materials during charge and discharge, resulting in better battery cycle performance (maintaining over 3000 cycles at a current density of 10 A / g), but also exhibits excellent rate performance, easily maintaining a specific capacity of 300 mAh / g at a current density of 50 A / g. Attached Figure Description

[0016] Figure 1 X-ray diffraction patterns of iron-based selenides from Examples 1-5 and Comparative Example 1;

[0017] Figure 2 The rate performance of iron-based selenides as anode materials for sodium-ion batteries in Examples 1-5 and Comparative Example 1;

[0018] Figure 3 Iron-based selenides used in Examples 1-5 and Comparative Example 1 as sodium-ion battery materials at 2 A·g -1 Cyclic performance graph of current density;

[0019] Figure 4 The iron-based selenides used in Examples 1-5 and Comparative Example 1 as sodium-ion battery materials at 10 A·g -1 Cyclic performance graph of current density. Detailed Implementation

[0020] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0022] Example 1: Preparation of High-Entropy Doped Iron-Based Selenides

[0023] The selenium powder, iron powder, nickel powder, manganese powder, copper powder, molybdenum powder, and silicon powder used in this embodiment have a purity greater than 99%, and the specific preparation method is as follows:

[0024] 564.00 mg selenium powder, 180.00 mg iron powder, 4.21 mg nickel powder, 3.93 mg manganese powder, 4.53 mg copper powder, 6.85 mg molybdenum powder, and 2.00 mg silicon powder (elemental molar ratio of 200:90:2:2:2:2:2) were loaded into a ball mill jar. After evacuating the transition chamber using a glove box, nitrogen gas was introduced. The ball mill jar was then tightened and removed from the transition chamber. The iron powder and selenium powder were ball-milled and mixed using a ball mill. The oscillation frequency was set to 1800 rpm, and the ball milling was performed for 8 cycles. Each cycle was ball-milled for 15 minutes and then allowed to stand for 5 minutes (the standing time was not included in the ball milling time). The total ball milling time was 2 hours.

[0025] After the ball milling process, the mixed powder was placed into a covered alumina ceramic boat and covered with carbon paper. The alumina ceramic boat was then placed in the middle of a tube furnace and nitrogen gas was introduced for 5 minutes to create a nitrogen atmosphere inside the furnace. The furnace was then heated to 550°C at a heating rate of 5°C / min and held at 550°C for 3 hours. Finally, the material was allowed to cool naturally to obtain the iron-based selenide material.

[0026] Example 2: Preparation of High-Entropy Doped Iron-Based Selenides

[0027] The preparation method of this embodiment is the same as that of Example 1, except that the powder raw materials used are: 564.00 mg selenium powder, 180.00 mg iron powder, 4.21 mg nickel powder, 6.85 mg molybdenum powder, 3.71 mg chromium powder, 13.14 mg tungsten powder and 2.00 mg silicon powder (the molar ratio of the elements is 200:90:2:2:2:2:2), to obtain high-entropy doped iron-based selenide.

[0028] Example 3: Preparation of High-Entropy Doped Iron-Based Selenides

[0029] The preparation method of this embodiment is the same as that of Example 1, except that the powder raw materials used are: 564.00 mg selenium powder, 180.00 mg iron powder, 4.21 mg nickel powder, 3.93 mg manganese powder, 4.53 mg copper powder, 3.71 mg chromium powder and 2.00 mg silicon powder (the molar ratio of the elements is 200:90:2:2:2:2:2), to obtain high-entropy doped iron-based selenide.

[0030] Example 4: Preparation of High-Entropy Doped Iron-Based Selenides

[0031] The preparation method of this embodiment is the same as that of Example 1, except that the powder raw materials used are: 564.00 mg selenium powder, 180.00 mg iron powder, 4.21 mg nickel powder, 6.85 mg molybdenum powder, 4.53 mg copper powder, 3.71 mg chromium powder and 2.00 mg silicon powder (the molar ratio of the elements is 200:90:2:2:2:2:2), to obtain high-entropy doped iron-based selenide.

[0032] Example 5: Preparation of High-Entropy Doped Iron-Based Selenides

[0033] The preparation method of this embodiment is the same as that of Example 1, except that the powder raw materials used are: 564.00 mg selenium powder, 180.00 mg iron powder, 4.21 mg nickel powder, 3.93 mg manganese powder, 4.53 mg copper powder, 13.14 mg tungsten powder and 2.00 mg silicon powder (the molar ratio of the elements is 200:90:2:2:2:2:2), to obtain high-entropy doped iron-based selenide.

[0034] Comparative Example 1: Preparation of Iron-Based Selenides

[0035] The preparation method of this embodiment is the same as that of Example 1, except that the powder raw materials used are: 564.00 mg selenium powder and 200 mg iron powder (elemental molar ratio of 200:100) to obtain iron-based selenide.

[0036] Example 1: Characterization of High-Entropy Doped Iron-Based Selenides

[0037] 1. Phase composition

[0038] The X-ray diffraction results of the samples from Examples 1-5 and Comparative Example 1 are as follows: Figure 1 As shown, comparative analysis with standard PDF cards of Fe3Se4 and FeSe2 reveals that the main components of the iron selenium compounds prepared in Examples 1-5 and Comparative Example 1 are Fe3Se4 and FeSe2.

[0039] 2. Electrical performance characterization

[0040] Electrode sheets were prepared from the samples of Examples 1-5 and Comparative Example 1, respectively. Using 0.8 mL of N-methylpyrrolidone (NMP) as a dispersant, 0.7 g of high-entropy doped iron-based selenide, 0.2 g of conductive carbon black, and 0.1 g of polyvinylidene fluoride were stirred evenly to obtain an adhesive slurry. This slurry was coated onto a current collector copper foil and then dried in a vacuum oven at 50 °C for 8 h. Electrode sheets with a diameter of 12 mm were obtained by a slicing machine.

[0041] Button batteries were assembled in a glove box filled with Ar and containing less than 1 ppm of both H2O and O2. Half-cells were assembled using the electrode sheets and sodium metal sheets prepared above, with a glass fiber membrane as the separator and a 1 mol / L sodium hexafluorophosphate diethylene glycol dimethyl ether solution as the electrolyte. The constant current charge-discharge cycle performance tests of the button batteries were conducted using a battery testing system (Neware, BTS) at room temperature.

[0042] The rate performance of the button cells composed of samples from Examples 1-5 and Comparative Example 1 is as follows: Figure 2 As shown, the button batteries composed of Examples 2, 3, 4, and 5 have a larger specific capacity than Comparative Example 1 at different current densities, exhibiting excellent rate performance.

[0043] The electrochemical cycling performance of the button cells in Examples 1-5 and Comparative Example 1 at a current density of 2 A / g is as follows: Figure 3 As shown, the capacity of Comparative Example 1 (without high-entropy doping) first decreased and then increased. The battery in Comparative Example 1 failed after approximately 500 cycles in low-current cycling, while the batteries in Examples 1-5 still functioned normally, demonstrating good stability. The electrochemical cycling performance of the coin cells composed of samples from Examples 1-5 and Comparative Example 1 at a current density of 10 A / g is as follows: Figure 4As shown, the battery prepared in Comparative Example 1 failed after 400 cycles under a high current of 10 A / g, while Examples 1-5 could easily achieve 3000 cycles with almost 100% capacity retention. The two cycle characterizations show that high-entropy doping can introduce a large number of lattice defects, which make the iron-based selenide material structure more robust and stable. When used as an anode material, it can effectively alleviate the volume expansion caused by sodium ion insertion and extraction, and can be more resistant to sodium ion insertion and extraction. This gives iron-based selenides better battery cycle performance as an anode material.

[0044] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-entropy doped iron-based selenide material, characterized in that, Under a protective atmosphere, iron powder, selenium powder and elemental powder are first ball-milled and mixed, and then calcined at 500~650℃ to obtain a high-entropy doped iron-based selenide material, which is a sodium-ion battery anode material. The elemental powder is any five combinations selected from nickel powder, chromium powder, copper powder, manganese powder, molybdenum powder, tungsten powder, and silicon powder. The elemental molar ratio of the selenium powder, iron powder and elemental powder is 200:(80~120):(8~15); The main components of the iron-based selenium compound are Fe3Se4 and FeSe2.

2. The method for preparing a high-entropy doped iron-based selenide material according to claim 1, characterized in that, The protective atmosphere is a nitrogen atmosphere.

3. The method for preparing a high-entropy doped iron-based selenide material according to claim 1, characterized in that, The calcination process involves heating to 500-650°C at a heating rate of 5°C / min and holding at that temperature for 3-4 hours.

4. The method for preparing a high-entropy doped iron-based selenide material according to claim 1, characterized in that, The ball milling time is 1-3 hours, and the ball milling oscillation frequency is set to 1800 rpm.

5. The high-entropy doped iron-based selenide material prepared by the preparation method according to any one of claims 1 to 4.

6. A sodium-ion battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode comprises a negative electrode current collector and a negative electrode material layer coated on the negative electrode current collector, characterized in that, The negative electrode material layer includes the high-entropy doped iron-based selenide material as described in claim 5.

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