High-entropy oxide Fe0. 2Co0. 2Ni0. 2Cu0. 2Zn0. 2O, ultrafast synthesis method and application

Abstract

The invention belongs to the technical field of energy storage materials, and particularly relates to a high-entropy oxide Fe0. 2Co0. 2Ni0. 2Cu0. 2Zn0. 2O and an ultrafast synthesis method and application thereof. According to the preparation method, ferroferric oxide, cobalt oxide, nickel oxide, copper oxide and zinc oxide with equal molar ratio are adopted as direct synthesis raw materials, toxic gases such as chlorine and nitrogen dioxide generated in the synthesis process of a metal salt precursor are avoided, and the uniformly distributed single-phase high-entropy oxide is synthesized in an ultrafast manner within 10 seconds by using a Joule heating technology; the synthesized high-entropy oxide is used as a lithium ion battery negative electrode material, and shows more excellent electrochemical performance and cycling stability compared with other high-entropy oxides prepared from transition metals with different proportions; in the preparation process, extra additives are not needed, operation is easy, the synthesis speed is high, the yield is high, element distribution is uniform, and the method has the advantages of being low in cost, high in efficiency and free of pollution and has the industrialization prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage materials, and specifically relates to a high entropy oxide Fe 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O. Ultrafast synthesis methods and applications. Background Art

[0002] Lithium-ion batteries, owing to their high efficiency and reliability, have become one of the most widely used energy storage solutions worldwide. However, the energy density of currently commercially used graphite intercalation anode materials is relatively low, and silicon-based anode materials suffer from severe volume expansion and poor stability, making them unable to meet the growing demand for high-energy-density energy storage. Transition metal oxides (HEOs) not only offer higher theoretical specific capacity, but also exhibit reduced volume expansion and improved cycling stability. Combining the principle of high configurational entropy stability, HEOs, which are prepared by combining multiple components (typically five or more, each at a molar concentration of 5-35%) to increase configurational entropy and form a single-phase crystal structure, are gradually gaining popularity as anode materials for lithium-ion batteries. Their highly uniform chemical composition and complex crystal structure endow HEOs with excellent structural stability, and the synergistic effects between the multiple elements enhance their electrochemical performance. These advantages make them highly promising anode materials for next-generation lithium-ion batteries. Currently, the preparation of HEOs typically involves synthesizing them from metal salt precursors, which can generate toxic gases such as chlorine and nitrogen dioxide during the synthesis process. Furthermore, the electrochemical performance of HEOs remains to be further improved. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a high entropy oxide Fe 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O. Ultrafast synthesis methods and applications.

[0004] The technical solution adopted by the present invention is as follows: a high entropy oxide Fe 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 The ultrafast synthesis method of FeO comprises the following steps: mixing ferroferric oxide, cobalt oxide, nickel oxide, copper oxide and zinc oxide in equal molar proportions, pressing the pressed tablets, placing the pressed tablets in a Joule heat apparatus under an inert gas atmosphere for Joule heat sintering heating, taking out the heated pressed tablets after cooling, grinding and crushing the pressed tablets to obtain a single-phase high entropy oxide FeO. 0.2 Co 0.2 Ni0.2 Cu 0.2 Zn 0.2 O.

[0005] Preferably, the ferrosoferric oxide, cobalt oxide, nickel oxide, copper oxide and zinc oxide are mixed by ball milling in a ball milling jar.

[0006] Preferably, the tablets are made by pressing 0.2-0.5 g of the mixed metal oxides into round tablets with a diameter of 1-1.5 cm under a pressure of 5-10 MPa.

[0007] Preferably, the inert gas is argon or nitrogen.

[0008] Preferably, the Joule heat sintering heating temperature is 800-1200° C., and the heating time is 3-15 seconds.

[0009] As mentioned above, the high entropy oxide Fe 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 High entropy oxide Fe O synthesized by ultrafast synthesis method 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O.

[0010] As mentioned above, the high entropy oxide Fe 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O application in the preparation of negative electrode materials for lithium batteries.

[0011] A method using the high entropy oxide Fe 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O prepared lithium negative electrode material for lithium-ion batteries.

[0012] A negative electrode of a lithium ion battery comprises a negative electrode active material, a conductive agent and a binder, wherein the negative electrode active material is the lithium negative electrode material of the lithium ion battery as described above.

[0013] A lithium ion battery comprises a positive electrode, a separator, an electrolyte and a negative electrode, wherein the negative electrode is the negative electrode of the lithium ion battery as described above.

[0014] The beneficial effects of the present invention are as follows: the present invention uses ferroferric oxide, cobalt oxide, nickel oxide, copper oxide, and zinc oxide in equal molar proportions as direct synthesis raw materials, eliminating the generation of toxic gases such as chlorine and nitrogen dioxide by metal salt precursors during the synthesis process, and utilizing Joule heating technology to ultra-fast synthesize uniformly distributed single-phase high-entropy oxides within 10 seconds. The synthesized high-entropy oxides are used as negative electrode materials for lithium-ion batteries, and exhibit better electrochemical properties and cycle stability than high-entropy oxides prepared from other transition metals with different proportions. The present invention does not require additional additives during the preparation process and has simple operation, fast synthesis speed, high yield, and uniform element distribution. It has the advantages of low cost, high efficiency, and pollution-free, and has prospects for industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying any creative work, other drawings obtained based on these drawings still fall within the scope of the present invention.

[0016] Figure 1 These are digital photos of the pressed discs before and after heat treatment;

[0017] Figure 2 Surface X-ray diffraction data of synthesized high entropy oxide;

[0018] Figure 3 The scanning electron microscope images of the synthesized high entropy oxide and five raw materials, (a) is the high entropy oxide Fe 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O(HEO), (b) CoO, (c) CuO, (d) NiO, (e) ZnO, (f) Fe3O4, and (g) the average particle size distribution of the six materials;

[0019] Figure 4 This is a transmission electron microscopy image of the synthesized high entropy oxide;

[0020] Figure 5 The cycling performance of the synthesized high entropy oxide as a lithium negative electrode material, (a) is the high entropy oxide at a current density of 0.1Ag -1 The charge and discharge curves of the first five cycles under the conditions (b) are the charge and discharge curves of high entropy oxide at a current density of 0.1Ag -1 Cyclic stability under the conditions, (c) high entropy oxide at a current density of 5Ag -1 Long-term cycle performance under

[0021] Figure 6 Comparison of the electrochemical performance of the synthesized high entropy oxide and five raw materials for forming high entropy oxides. (a) is high entropy oxide Fe 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 (b) The electrochemical properties of O(HEO), (c) The electrochemical properties of CuO, (d) The electrochemical properties of NiO, (e) The electrochemical properties of ZnO, and (f) The electrochemical properties of Fe3O4;

[0022] Figure 7 To compare the electrochemical performance of the synthesized high entropy oxide with that of high entropy oxides with other ratios;

[0023] Figure 8 Transmission electron microscope images of lithium-ion batteries after first discharge and charge;

[0024] Figure 9 X-ray photoelectron spectroscopy analysis of high entropy oxide at initial, discharged, and charged states;

[0025] Figure 10 Structural changes during lithium battery cycling. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be described in further detail below with reference to the accompanying drawings.

[0027] The present invention provides an ultrafast synthesis of high entropy oxide Fe 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 The method comprises the following steps: mixing ferroferric oxide, cobalt oxide, nickel oxide, copper oxide, and zinc oxide in equal molar proportions and then pressing the mixture into tablets; sintering the mixture under an inert gas atmosphere by Joule heat; and cooling the mixture and grinding the sample to obtain a single-phase high-entropy oxide material. The present invention innovatively utilizes Joule heating technology to ultrafast synthesize a high-entropy oxide Fe with a rock salt structure. 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O and applied it as a conversion-type anode material for lithium-ion batteries for the first time. Ultrafast thermal excitation achieves uniform atomic-scale distribution of the elements, and the five transition metal oxides synergize in an optimal ratio to form a pure-phase rock salt structure. This enables highly reversible lithium storage in lithium-ion batteries.

[0028] In some embodiments of the present invention, the tablets are formed by pressing 0.2-0.5 g of the mixed metal oxides into round tablets with a diameter of 1-1.5 cm at a pressure of 5-10 MPa.

[0029] In some embodiments of the present invention, the inert gas is argon or nitrogen.

[0030] In some embodiments of the present invention, the Joule heat sintering heating temperature is 800-1200° C., and the heating time is 3-15 seconds.

[0031] Example 1:

[0032] First, ferroferric oxide, cobalt oxide, nickel oxide, copper oxide, and zinc oxide in equal molar proportions are placed in a zirconium oxide mixing tank and mixed with stainless steel beads in a ball mill at a speed of 400 rpm for 4 hours. The mixed powder is then divided into 0.35 g equal parts, placed in a hydraulic press at a pressure of 8 MPa, and pressed into small discs with a diameter of 1.5 cm. During Joule heat sintering, a graphite sheet is first used as a support and conductor to ensure uniform heating. A sandwich structure of alumina sheet-pressed precursor disc-alumina sheet is placed in the center of the graphite sheet, and another graphite sheet is placed on top of it and fixed with graphite screws. It is then heated to 1100 degrees Celsius in 3 seconds in a heating chamber filled with argon and then rapidly cooled to room temperature. The entire process is completed within 10 seconds. The fired high-entropy oxide is ground and pulverized to finally obtain the synthesized high-entropy oxide.

[0033] Digital photos of pressed discs before and after heat treatment Figure 1 As shown in Figure 3, after heat treatment, the diameter of the sintered sample shrinks to 1.3 cm due to densification and porosity reduction during the sintering process.

[0034] Test Example 1:

[0035] The X-ray diffraction data of the synthesized high entropy oxide are as follows Figure 2 As shown, the structural characteristics of the synthetic sample were analyzed at an angle of 20-80, and the analysis confirmed that it was a single rock salt structure.

[0036] Test Example 2:

[0037] The morphology of the synthesized high entropy oxide and the five oxide raw materials forming the high entropy oxide were characterized by scanning electron microscopy. Figure 3 As shown in the figure, the particle sizes of the six materials were similar, eliminating the influence of size on the subsequent electrochemical performance of the battery. The structural characteristics of the synthesized high entropy oxide were analyzed by transmission electron microscopy. The results are shown in Figure 4 As shown, the synthesized material exhibits a polycrystalline rock salt structure, and the Fe, Co, Ni, Cu, Zn and O elements are uniformly distributed at the atomic scale.

[0038] Test Example 3:

[0039] The electrochemical performance of the high entropy oxide negative electrode was tested using a CR2032 button-type half-cell. The synthesized high entropy oxide, Ketjen black, and sodium alginate were mixed in deionized water at a weight ratio of 7:2:1, ball-milled at 2000 rpm for 10 minutes, and the mixed material was evenly coated on a copper foil. The copper foil was then placed in an oven at 80°C and dried for 12 hours. The dried copper foil was then punched into discs with a diameter of 12 mm. The loading of the active material was determined to be ≈1.0 mg cm by electronic balance measurement. -2 The electrolyte is 1 mol L dissolved in a mixture of ethylene carbonate / dimethyl carbonate / diethyl carbonate. -1 LiPF6, volume ratio 1:1:1, separator is glass fiber GF / D. CR2032 button cell was assembled in an argon-filled glove box. Using Xinwei battery test system, the cycle performance of half cell was tested at constant current density. The battery test data results are shown in the figure. Figure 5 As shown, at a current density of 0.1Ag -1 The reversible capacity after 200 cycles is 1310 mAh g -1 , at a relatively high current density of 5Ag -1 The capacity can also maintain 705mAh g after 3000 cycles -1 , the material exhibits excellent electrochemical performance and outstanding capacity retention.

[0040] Test Example 4:

[0041] The electrochemical performance of high entropy oxides was compared with five raw materials (CoO, CuO, NiO, ZnO, Fe3O4) that form high entropy oxides. Figure 6 As shown, the six materials have a current density of 3Ag -1 After 1000 cycles, the reversible capacity of the high entropy oxide is 947 mAh g -1 , CoO is 324 mAh g -1 , CuO is 237 mAh g -1 , NiO is 170 mAh g -1 , ZnO is 54 mAh g -1 , Fe3O4 is 137mAh g -1 , Fe synthesized by Joule heat 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 The electrochemical performance of O-type high entropy oxides is significantly improved compared with that of single transition metals.

[0042] Test Example 5:

[0043] Different transition metal oxides were used as raw materials to prepare high entropy oxides with different transition metal ratios. The electrochemical performance of Example 1 was compared with that of high entropy oxides with different transition metal ratios. Figure 7 As shown, compared with the performance of 15 other high entropy oxides with different transition metal ratios, it exhibits more excellent electrochemical performance.

[0044] Test Example 6:

[0045] The structural evolution of high entropy oxides during lithium-ion battery cycling was analyzed by transmission electron microscopy. Figure 8 As shown in the figure, the negative electrode materials of lithium-ion batteries were structurally characterized after the first discharge and charge, respectively. It can be observed that after discharge, the original rock salt structure is partially retained to maintain a reversible structural framework, and part of the oxide forms a single substance, which reversibly recovers to the rock salt structure after charging.

[0046] Test Example 7:

[0047] The element valence states of high entropy oxide at the initial, discharged and charged states are analyzed to determine the role of each element in the battery cycle process. The corresponding X-ray photoelectron spectroscopy analysis is as follows: Figure 9 Electrochemically inactive zinc oxide and some iron and cobalt oxides help maintain the rock salt framework, Cu 2+ Irreversibly reduced to metallic Cu 0 , establishing a conductive network and promoting fast lithium-ion storage kinetics.

[0048] Test Example 8:

[0049] In situ X-ray diffraction analysis of half-cells was performed at an operating voltage of 40 V, a current of 40 mA, and an angle between 20 and 80 degrees to observe the structural changes during lithium battery cycling. Figure 10 As shown, the rock salt structure exists throughout the entire cycle and does not disappear completely.

[0050] The above disclosure is merely a preferred embodiment of the present invention and certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A high entropy oxide Fe 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 An ultrafast synthesis method for O, characterized in that The method comprises the following steps: mixing ferroferric oxide, cobalt oxide, nickel oxide, copper oxide and zinc oxide in equal molar proportions, pressing the pressed tablets, placing the pressed tablets in a Joule heat apparatus under an inert gas atmosphere for Joule heat sintering heating, taking out the heated pressed tablets after cooling, grinding and crushing the pressed tablets to obtain a single-phase high entropy oxide Fe 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O.

2. The high entropy oxide Fe according to claim 1 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 An ultrafast synthesis method for O, characterized in that: The ferroferric oxide, cobalt oxide, nickel oxide, copper oxide and zinc oxide are placed in a ball mill tube and mixed by ball milling.

3. The high entropy oxide Fe according to claim 1 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 An ultrafast synthesis method for O, characterized in that: The tablets are made by pressing 0.2-0.5 g of the mixed metal oxides into round tablets with a diameter of 1-1.5 cm under a pressure of 5-10 MPa.

4. The high entropy oxide Fe according to claim 1 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 An ultrafast synthesis method for O, characterized in that: The inert gas is argon or nitrogen.

5. The high entropy oxide Fe according to claim 1 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 An ultrafast synthesis method for O, characterized in that: The Joule heat sintering heating temperature is 800-1200° C., and the heating time is 3-15 seconds.

6. The high entropy oxide Fe according to any one of claims 1 to 5 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 High entropy oxide Fe O synthesized by ultrafast synthesis method 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O.

7. The high entropy oxide Fe according to claim 6 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O application in the preparation of negative electrode materials for lithium batteries.

8. A method using the high entropy oxide Fe as claimed in claim 6 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O prepared lithium negative electrode material for lithium-ion batteries.

9. A negative electrode for a lithium-ion battery, comprising a negative electrode active material, a conductive agent, and a binder, characterized in that: The negative electrode active material is the lithium negative electrode material of the lithium ion battery as claimed in claim 8.

10. A lithium-ion battery comprising a positive electrode, a separator, an electrolyte and a negative electrode, characterized in that: The negative electrode is the negative electrode of the lithium ion battery according to claim 9.

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