A method for preparing a high-entropy oxide having a heterojunction

Abstract

The application discloses a preparation method of high-entropy oxide with a heterojunction, and comprises the following steps: S1, weighing equal-molar metal elements of Fe2O3, Cr2O3, MnO2 and ZnO, and then weighing TiO2 and a volatile organic solvent and adding them into a ball mill jar; S2, drying the materials in an oven; and S3, calcining the materials in an oxygen-containing atmosphere, and obtaining high-entropy oxide after cooling to room temperature, wherein the heterostructure of the high-entropy oxide is composed of (FeZnCrMn)3O4 and TiO2. The lithium ion battery negative electrode (FeZnCrMn)3O4 / TiO2 obtained by the method has a unique and rich heterojunction interface of high-entropy oxide; the method is simple to operate, controllable, good in repeatability, wide in applicability and suitable for industrial production; and the battery assembled by the obtained high-entropy oxide negative electrode material (FeZnCrMn)3O4 / TiO2 with a heterojunction can maintain excellent cycle stability under an ultrahigh current density, and has remarkable economic value.

Description

Technical Field

[0001] This invention relates to a method for preparing a battery anode material, specifically a method for preparing a high-entropy oxide with a heterojunction, in the fields of high-entropy oxide synthesis and battery fabrication. Background Technology

[0002] Lithium-ion batteries (LIBs) offer advantages over other energy storage devices, including high energy density, strong charge retention, and long charge-discharge life, making them a key component in portable electronic devices, electric vehicles, and power management. In recent years, high-entropy oxides (HEOs), derived from the concept of high-entropy alloys (HE), have attracted attention for the development of advanced LIBs.

[0003] The key concept of HEO is to use multiple components (typically five or more, each with a concentration of 5-35%) to increase configurational entropy, providing a stable driving force. As an anode material for lithium-ion batteries (LIBs), HEO has a huge potential market. First, during lithium-ion insertion / extraction, the lattice distortion effect significantly reduces the resistance to ion migration within the HEO crystal structure. Furthermore, the coexistence of elements with different valence states during HEO preparation creates a large number of oxygen vacancies, thereby improving its conductivity. High-entropy oxides composed of different elements have different physicochemical characteristics. Studies have shown that HEO also exhibits certain inherent defects: first, large volume expansion, which severely impairs battery life; second, poor conductivity, which easily leads to electrode polarization and rate performance degradation.

[0004] Currently, almost all reported HEO materials are single-phase solid solutions composed of multiple elements in similar atomic proportions, while the kinetics and electrochemical effects of heterogeneous formation have not been studied. Therefore, introducing other oxides to form heterostructures with HEO is an emerging research direction for improving the electrochemical performance of HEO. The interface between different substances plays a crucial role in improving electrochemical performance; the interface exhibits significantly different properties from single-phase materials in heterostructures, and the heterojunction interface also determines the interaction mode between the heterostructures. The high-entropy oxide heterojunction interface effect mainly optimizes the material in different aspects of lithium-ion battery systems, including electron transfer, strain, and the formation of new active sites. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this invention is to provide a method for preparing high-entropy oxides with heterojunctions, thereby solving the problems of large volume expansion and poor conductivity of high-entropy oxides with single solid solutions.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a high-entropy oxide with a heterojunction includes the following steps:

[0008] S1: Weigh equimolar amounts of Fe2O3, Cr2O3, MnO2, and ZnO, then weigh a certain amount of TiO2 and a volatile organic solvent and add them together into a ball mill jar for ball milling. The time is 2-4 hours. The mass ratio of tungsten carbide balls to the total mass of the five oxides is 1-5:1, and the rotation speed is 150-400 rpm.

[0009] S2: Place the material obtained in S1 into an oven and dry it at 60-120℃ for 6-24 hours;

[0010] S3: The dried material from S2 is calcined in an oxygen-containing atmosphere at a temperature of 800–1200℃, a holding time of 8–16 h, and a heating rate of 3–8℃ / min. After cooling to room temperature, a high-entropy oxide with the chemical formula (FeZnCrMn)3O4 / TiO2 and a heterostructure is obtained. Its heterostructure is composed of (FeZnCrMn)3O4 and TiO2.

[0011] Furthermore, the molar ratio of the metal elements in TiO2 added in step S1 to those in other metal oxides is 0.7-1.2:1.

[0012] Furthermore, the oxygen-containing atmosphere used in step S3 is either air or pure oxygen.

[0013] The beneficial effects of the preparation method of the present invention are as follows:

[0014] (1) The lithium-ion battery anode (FeZnCrMn)3O4 / TiO2 obtained by the method of the present invention has a unique and abundant high-entropy oxide heterojunction interface, and the morphological particles exhibit diversity with a particle size of 500-800 nm.

[0015] (2) The method of the present invention has a short process, simple operation, strong controllability, good repeatability, wide applicability, and is suitable for industrial production;

[0016] (3) The high-entropy oxide anode material (FeZnCrMn)3O4 / TiO2 with heterojunction obtained by the method of the present invention is assembled into a lithium-ion battery. The voltage range is 0-3V. At a current density of 100mA / g, the initial discharge specific capacity can reach 1290.1mAh / g, and the coulombic efficiency is stable. At a current density of 5A / g, the initial reversible discharge specific capacity can still reach 735.9mAh / g. After 2000 cycles, the discharge specific capacity can still reach 588.6mAh / g, and the capacity retention rate can reach 79.98%. This shows that the battery assembled by the high-entropy oxide anode material (FeZnCrMn)3O4 / TiO2 with heterojunction obtained by the present invention can maintain excellent cycle stability at ultra-high current density and has significant economic value. Attached Figure Description

[0017] Figure 1 The image shows the XRD pattern of the lithium-ion battery anode material (FeZnCrMn)3O4 / TiO2 obtained in Example 1 of this invention.

[0018] Figure 2 This is a SEM image of the lithium-ion battery anode material (FeZnCrMn)3O4 / TiO2 obtained in Example 1 of this invention;

[0019] Figure 3 This is a TEM image of the lithium-ion battery anode material (FeZnCrMn)3O4 / TiO2 obtained in Example 1 of this invention;

[0020] Figure 4 The graph shows the charge-discharge rate performance of a lithium-ion battery assembled from the lithium-ion battery anode material (FeZnCrMn)3O4 / TiO2 obtained in Example 1 of this invention.

[0021] Figure 5 The graph shows the charge-discharge cycle performance of a lithium-ion battery assembled from the lithium-ion battery anode material (FeZnCrMn)3O4 / TiO2 obtained in Example 1 of this invention.

[0022] Figure 6 The image shows the XRD pattern of the lithium-ion battery anode material (FeZnCrMnTi)3O4 obtained in Example 1 of this invention.

[0023] Figure 7 This is a SEM image of the lithium-ion battery anode material (FeZnCrMnTi)3O4 obtained in Example 1 of the present invention. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings.

[0025] Example 1

[0026] A method for preparing a high-entropy oxide with a heterojunction includes the following steps:

[0027] S1: Weigh 10 mmol of Fe2O3, Cr2O3, MnO2, and ZnO respectively, and weigh 8 mmol of TiO2 and 2 ml of ethanol. Add the above materials to a ball mill jar, add tungsten carbide balls at a mass ratio of 2:1 to the total mass of the five oxides, and then ball mill at 250 r / min for 3 h to obtain material A;

[0028] S2: Place the material obtained in S1 into an oven and dry it at 80℃ for 12 hours;

[0029] S3: The material dried in step S2 is calcined again at a temperature of 1000℃ for 10 hours, with a heating rate of 5℃ / min and an atmosphere of air. The material is then rapidly annealed to room temperature to obtain a high-entropy oxide (FeZnCrMn)3O4 / TiO2 with a heterojunction.

[0030] like Figure 1 As shown, the peak values ​​of the lithium battery anode material (FeZnCrMn)3O4 / TiO2 obtained in this embodiment on XRD are basically consistent with those of the standard, and there are no impurity peaks. It can be determined that (FeZnCrMn)3O4 and TiO2 in the obtained material are pure phase substances.

[0031] like Figure 2 The image shows the morphology of the lithium-ion battery anode material (FeZnCrMn)3O4 / TiO2 powder obtained in this embodiment.

[0032] The particles exhibit morphological diversity, with diameters ranging from 500 to 800 nm, meaning that the samples synthesized after heat treatment consist of submicron (FeZnCrMn)3O4 / TiO2.

[0033] like Figure 3 The image shown is a TEM image of the lithium-ion battery anode material (FeZnCrMn)3O4 / TiO2 powder obtained in this embodiment. After high-temperature treatment, the oxide powder underwent fusion and resegregation, revealing a clear high-entropy oxide heterojunction interface.

[0034] like Figure 4 , 5The figure shows the charge / discharge rate performance and high-current long-cycle performance of (FeZnCrMn)3O4 / TiO2 lithium-ion battery. As shown in the figure, at a current density of 0.1 A / g, the initial discharge specific capacity reaches 1290.1 ​​mAh g⁻¹, and the initial charge specific capacity reaches 833.8 mAh g⁻¹, exhibiting an initial coulombic efficiency of 64.6%, demonstrating good rate performance. At a current density of 5 A / g, its initial reversible discharge specific capacity still reaches 735.9 mAh / g, and after 2000 cycles, its discharge specific capacity still reaches 588.6 mAh / g, with a capacity retention rate of 79.98%.

[0035] Example 2

[0036] A method for preparing a high-entropy oxide with a heterojunction includes the following steps:

[0037] S1: Weigh 10 mmol of Fe2O3, Cr2O3, MnO2, and ZnO respectively, then weigh 6 mmol of TiO2 and 2 ml of ethanol. Add the above materials to a ball mill jar, add tungsten carbide balls at a mass ratio of 1:1 to the total mass of the five oxides, and then ball mill at 300 r / min for 2 h.

[0038] S2: Place the material obtained in S1 into an oven and dry it at 60℃ for 24 hours;

[0039] S3: The material dried in step S2 is calcined again at a temperature of 900℃ for 8 hours, with a heating rate of 3℃ / min and an atmosphere of air. The material is then rapidly annealed to room temperature to obtain a high-entropy oxide (FeZnCrMn)3O4 / TiO2 with a heterojunction.

[0040] like Figure 6 As shown, the peak values ​​of the lithium battery anode material (FeZnCrMnTi)3O4 obtained in this embodiment on XRD are basically consistent with those of the standard, and there are no impurity peaks. It can be determined that the (FeZnCrMnTi)3O4 in the obtained material is a pure phase substance.

[0041] like Figure 7 As shown, the lithium battery anode material (FeZnCrMnTi)3O4 obtained in this embodiment has a uniform morphology and is composed of nanoparticles with a particle size of 300-500 nm.

[0042] The rate performance and cycle performance of (FeZnCrMnTi)3O4 were specifically tested. The initial discharge capacity reached 778.4 mAh g at a current density of 0.1 A / g. -1 The initial charging capacity reaches 435.6mAh g. -1It has a first-cycle coulomb efficiency of only 55.9%; and a capacity of 254.5 mAh g after 500 cycles at 0.5 A / g. -1 Reversible capacity.

[0043] Compared to Example 1, the lithium-ion battery assembled from the pure-phase (FeZnCrMnTi)3O4 anode material obtained in Example 2 exhibits poor electrochemical performance. In contrast, the (FeZnCrMn)3O4 / TiO2 material with a nano-high-entropy oxide heterojunction shown in Example 1 demonstrates excellent electrochemical performance. This indicates that only appropriate elemental ratios and suitable preparation processes can form a heterojunction interface between high-entropy oxides and TiO2.

[0044] Example 3

[0045] A method for preparing a high-entropy oxide with a heterojunction includes the following steps:

[0046] S1: Weigh 10 mmol of Fe2O3, Cr2O3, MnO2, and ZnO respectively, then weigh 7 mmol of TiO2 and 2 ml of ethanol. Add the above materials to a ball mill jar, add tungsten carbide balls at a mass ratio of 3:1 to the total mass of the five oxides, and then ball mill at 150 r / min for 2.5 h.

[0047] S2: Place the material obtained in S1 into an oven and dry it at 100℃ for 8 hours;

[0048] S3: The material dried in step S2 is calcined again at a temperature of 800℃ for 16 hours, with a heating rate of 4℃ / min and a high-purity oxygen atmosphere. The material is then rapidly annealed to room temperature to obtain a high-entropy oxide (FeZnCrMn)3O4 / TiO2 with a heterojunction.

[0049] The peak values ​​of the lithium-ion battery anode material (FeZnCrMn)3O4 / TiO2 obtained in this embodiment on XRD are basically consistent with those of the standard, and there are no impurity peaks. It can be determined that (FeZnCrMn)3O4 and TiO2 in the obtained material are pure phase substances.

[0050] The lithium-ion battery anode material (FeZnCrMn)3O4 / TiO2 powder obtained in this embodiment exhibits morphological diversity, with a diameter range of 400–600 nm, meaning that the sample synthesized after heat treatment is composed of submicron (FeZnCrMn)3O4 / TiO2.

[0051] The rate performance and cycling performance of (FeZnCrMn)3O4 / TiO2 were specifically tested. At a current density of 0.1 A / g, the initial discharge capacity reached 1127.4 mAh g-1, and the initial charge capacity reached 738.4 mAh g-1, with an initial coulombic efficiency of only 65.5%, indicating good rate performance. After 2000 cycles at 5 A / g, it had a reversible capacity of 523.5 mAh g-1, demonstrating excellent cycling performance.

[0052] Example 4

[0053] A method for preparing a high-entropy oxide with a heterojunction includes the following steps:

[0054] S1: Weigh 10 mmol of Fe2O3, Cr2O3, MnO2, and ZnO respectively, and then weigh 10 mmol of TiO2 and 2 ml of ethanol. Add the above materials to a ball mill jar, add tungsten carbide balls at a mass ratio of 5:1 to the total mass of the five oxides, and then ball mill at 400 r / min for 4 h.

[0055] S2: Place the material obtained in S1 into an oven and dry it at 120℃ for 16 hours;

[0056] S3: The material dried in step S2 is calcined again at a temperature of 1200℃ for 12 hours, with a heating rate of 6℃ / min and a high-purity oxygen atmosphere. The material is then rapidly annealed to room temperature to obtain a high-entropy oxide (FeZnCrMn)3O4 / TiO2 with a heterojunction.

[0057] The peak values ​​of the lithium-ion battery anode material (FeZnCrMn)3O4 / TiO2 obtained in this embodiment on XRD are basically consistent with those of the standard, and there are no impurity peaks. It can be determined that (FeZnCrMn)3O4 and TiO2 in the obtained material are pure phase substances.

[0058] The lithium-ion battery anode material (FeZnCrMn)3O4 / TiO2 powder obtained in this embodiment exhibits morphological diversity, with a diameter range of 600–900 nm, meaning that the sample synthesized after heat treatment is composed of submicron (FeZnCrMn)3O4 / TiO2.

[0059] The rate performance and cycle performance of (FeZnCrMn)3O4 / TiO2 were specifically tested. The initial discharge capacity reached 1027.4 mAh g at a current density of 0.1 A / g. -1 The initial charging capacity reaches 652.1mAh g. -1 It has a first-cycle coulombic efficiency of 63.5% and good rate performance; after 2000 cycles at 5 A / g, it has a capacity of 467.5 mAh g.-1 It has a reversible capacity and excellent cycle performance.

[0060] Example 5

[0061] A method for preparing a high-entropy oxide with a heterojunction includes the following steps:

[0062] S1: Weigh 10 mmol of Fe2O3, Cr2O3, MnO2, and ZnO respectively, then weigh 12 mmol of TiO2 and 2 ml of ethanol. Add the above materials to a ball mill jar, adding tungsten carbide balls at a mass ratio of 4:1 to the total mass of the five oxides, and then ball mill at 200 r / min for 3.5 h.

[0063] S2: Place the material obtained in S1 into an oven and dry it at 70℃ for 20 hours;

[0064] S3: The material dried in step S2 is calcined again at a temperature of 950℃ for 10 hours, with a heating rate of 8℃ / min and an atmosphere of air. The material is then rapidly annealed to room temperature to obtain a high-entropy oxide (FeZnCrMn)3O4 / TiO2 with a heterojunction.

[0065] The peak values ​​of the lithium-ion battery anode material (FeZnCrMn)3O4 / TiO2 obtained in this embodiment on XRD are basically consistent with those of the standard, and there are no impurity peaks. It can be determined that (FeZnCrMn)3O4 and TiO2 in the obtained material are pure phase substances.

[0066] The lithium-ion battery anode material (FeZnCrMn)3O4 / TiO2 powder obtained in this embodiment exhibits diverse morphologies with diameters ranging from 800 to 900 nm.

[0067] The rate performance and cycle performance of (FeZnCrMn)3O4 / TiO2 were specifically tested. The initial discharge capacity reached 992.4 mAh g at a current density of 0.1 A / g. -1 The initial charging capacity reaches 669.9mAh g. -1 It has a first-cycle coulombic efficiency of 67.5% and good rate performance; after 2000 cycles at 5 A / g, it has a capacity of 442.2 mAh g. -1 It has a reversible capacity and excellent cycle performance.

[0068] As can be seen from the above, the lithium-ion battery assembled from the lithium-ion battery anode material (FeZnCrMn)3O4 / TiO2 obtained in the embodiments of the present invention has high specific capacity and good cycle stability. Compared with the high-entropy oxide (FeZnCrMnTi)3O4, (FeZnCrMn)3O4 / TiO2 has superior discharge specific capacity and cycle stability. This is attributed to its constructed heterojunction, which can effectively improve the transport of ions and electrons and enhance the conductivity of the material. This patent innovatively constructs a heterojunction on the surface of a high-entropy oxide for the first time, improving the electrochemical performance of HEO.

[0069] The preparation method provided by this invention is simple, highly operable, and suitable for industrial production. Its application and promotion will positively contribute to the preparation and application of high-capacity electrode materials. Therefore, this invention has significant social and economic value.

Claims

1. A method for preparing a high-entropy oxide having a heterojunction, characterized by, Includes the following steps: S1: Weigh equimolar amounts of Fe2O3, Cr2O3, MnO2, and ZnO, then weigh a certain amount of TiO2 and a volatile organic solvent and add them together into a ball mill jar for ball milling for 2-4 hours. The mass ratio of tungsten carbide balls to the total mass of the five oxides is 1-5:1, and the rotation speed is 150-400 rpm. S2: Place the material obtained in S1 into an oven and dry it at 60-120℃ for 6-24 hours; S3: The dried material from S2 is calcined in an oxygen-containing atmosphere at a temperature of 800–1200℃, a holding time of 8–16 h, and a heating rate of 3–8℃ / min. After cooling to room temperature, a high-entropy oxide with the chemical formula (FeZnCrMn)3O4 / TiO2 and a heterostructure is obtained. Its heterostructure is composed of (FeZnCrMn)3O4 and TiO2.

2. The method for preparing a high-entropy oxide with a heterojunction according to claim 1, characterized in that, The molar ratio of the metal elements in TiO2 added in step S1 to those in other metal oxides is 0.7-1.2:

1.

3. The method for preparing a high-entropy oxide with a heterojunction according to claim 1, characterized in that, The oxygen-containing atmosphere used in step S3 is either air or pure oxygen.

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