Preparation method of high entropy oxide and positive electrode material

Abstract

The present invention relates to the technical field of sodium-ion batteries, and more particularly to a method for preparing a high-entropy oxide and a positive electrode material. The preparation method comprises: weighing sodium, nickel, magnesium, copper, iron, manganese, titanium, and tin metal powders in molar ratios, uniformly mixing them, and then pressing them into a metal mixed pellet; treating the metal mixed pellet using a laser sputtering method, and collecting the sputtered high-entropy oxide powder. A buckle battery using the high-entropy oxide prepared by the laser sputtering method as the active material for the positive electrode material exhibits excellent electrochemical performance and cycle performance. At a charge and discharge rate of 3C, the reversible capacity remains as high as 92 mAh / g after 500 cycles.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion batteries, and in particular to a preparation method of a high entropy oxide and a positive electrode material. Background Art

[0002] High-entropy metal oxides (HEOs) are a new type of composite compound that has attracted widespread scientific attention due to their unique structure and high-entropy properties. HEOs are single-phase, multi-element metal oxide systems in which different elements can have different crystal structures. HEOs are typically composed of five or more elements mixed in equal proportions, sharing the same atomic sites to form a stable solid solution. Due to their extremely complex composition, they often exhibit excellent properties such as high catalytic activity, high strength, good high / low temperature performance, and good energy storage properties.

[0003] In recent years, sodium-ion batteries (Na-ion batteries) have garnered widespread attention from both academia and industry due to their low cost and abundant resources. A wide variety of cathode materials have been proposed, including oxides, polyanionic compounds, and Prussian blue-based compounds. Layered oxides have attracted significant attention due to their high energy density, ease of synthesis, high structural stability, and excellent reversibility of sodium ion insertion / extraction. To develop high-performance novel materials, a wide range of metallic elements, such as 3d transition metals (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn), alkali / alkaline earth metals (Li, Mg, Ca), and 4d / 5d transition metals (Ru, Sn, Sb, Te, Ir, Bi), and even vacancies, have been introduced into the TM lattice sites of functional layered oxide (Na-TMO) systems. However, reported Na-TMO layered oxides with five or more metallic elements are rare. Therefore, exploring the potential role of high-entropy chemistry in layered oxide cathodes is of particular interest.

[0004] Chinese Patent Publication No. CN115231623B discloses a high-entropy metal oxide material, its preparation method, and battery. The chemical formula of the high-entropy metal oxide material disclosed in the invention is M2O3(AO3)6, where A is one element selected from Mo or W; M is five or more elements selected from Al, Ga, In, Y, V, Cr, Fe, Mn, Co, Ni, Sb, and Bi, and the stoichiometric ratios of the elemental components are equal. The material has good rate performance and can be discharged at medium to high rates above 1C. It has low discharge heat generation, low battery temperature rise, and small volume expansion, making it an excellent electrode material. The material preparation method provided by the present invention is simple, has low production cost, and is suitable for large-scale production. As can be seen from this, the process for preparing the high-entropy metal oxide in this invention is complicated and takes a long time to prepare. Summary of the Invention

[0005] To this end, the present invention provides a preparation method of a high entropy oxide and a positive electrode material to overcome the problem of a cumbersome synthesis process caused by the complexity of the preparation method of high entropy oxide in the prior art.

[0006] To achieve the above objectives, the present invention provides a method for preparing a high entropy oxide, comprising:

[0007] Weigh the metal powders of each component in molar ratio, including sodium, nickel, magnesium, copper, iron, manganese, titanium and tin;

[0008] Grinding the metal powders in a mortar to uniformly mix the metal powders;

[0009] Pressing the uniformly mixed metal powder into a multi-metal mixed tablet;

[0010] A laser sputtering synthesis device is used to treat a multi-metal mixed pellet placed in a preset atmosphere by a laser sputtering method, and a line scan is performed in a scanning area with a line spacing of 0.001 mm for a set time, and then the sputtered high entropy oxide powder is collected on a substrate;

[0011] Wherein, the metal powder includes metal elements, metal salts, metal oxides, metal chlorides and metal nitrates;

[0012] The molar ratio of the metal elements in each of the metal powders is:

[0013] Na: Ni: Mg: Cu: Fe: Mn: T i: Sn=1: 0.25: 0.05: 0.1: 0.2: 0.2: 0.1: 0.102;

[0014] The preset atmosphere includes oxygen, argon, nitrogen, air and argon-hydrogen mixture;

[0015] The heat source used in the laser sputtering method is a fiber laser.

[0016] Furthermore, the pressing process includes using a cold isostatic press to tablet the uniformly mixed metal powder;

[0017] The tableting pressure was set to 0.5 KPa, and the tableting time was set to 5 s to 10 s.

[0018] Furthermore, the laser power used in the laser sputtering process ranges from 10% to 100%, and the scanning rate ranges from 100 to 2000 mm / s.

[0019] Furthermore, a pigment tracer is added to the mortar containing the metal powder, and the tracer and the metal powder are mixed evenly, so as to judge whether the metal powder is mixed evenly by the color uniformity of the color tracer in the metal powder.

[0020] Furthermore, after the tableting density is determined by the thickness of the multi-metal mixed tableting, the compaction degree of the tableting is judged according to the tableting density, and whether secondary tableting is required is determined according to the compaction degree.

[0021] Furthermore, the composition of the preset atmosphere is determined according to the oxygen content of the metal powder during the laser sputtering process;

[0022] If the oxygen content in the metal powder is lower than the minimum oxygen content, it is determined that the preset atmosphere needs to contain oxygen;

[0023] The minimum oxygen content is twice the amount of Na atoms.

[0024] Furthermore, the crystal consistency of the high entropy oxide is determined based on the roughness of the high entropy oxide powder on the substrate surface, and the substrate temperature during laser sputtering is adjusted based on the crystal consistency.

[0025] Furthermore, the method for determining the crystal consistency of the high entropy oxide according to the roughness of the high entropy oxide powder on the surface of the substrate includes:

[0026] Acquiring a roughness image of the high entropy oxide powder on a substrate surface;

[0027] comparing the roughness of the roughness image with the roughness of several standard roughness images to determine the crystal consistency of the high entropy oxide;

[0028] The determination result of the crystal consistency includes crystal and amorphous structures.

[0029] Furthermore, the substrate temperature during laser sputtering is adjusted according to the crystal consistency determination result:

[0030] When the crystal consistency of the high entropy oxide powder on the surface of the substrate is an amorphous structure, the adjusted substrate temperature is determined based on the ratio of the current roughness value corresponding to the current roughness image to the standard roughness value corresponding to the standard roughness image and the current substrate temperature.

[0031] On the other hand, the present invention also provides a high entropy oxide positive electrode material, which is prepared using the above-mentioned high entropy oxide.

[0032] Compared with the prior art, the beneficial effect of the present invention is that the preparation method of high entropy oxide provided by the present invention has a simple preparation process and low cost, greatly improves production efficiency, can better meet the needs of industrial production, realize large-scale production, and has great application prospects.

[0033] Furthermore, the preparation method provided by the present invention designs a fiber laser as a heat source, and utilizes the plasma effect, photothermal effect and energy localization characteristics of the laser to synthesize a high-entropy oxide positive electrode material with an O3-type structure; this method is easy to operate, greatly reduces the complexity of the synthesis steps compared to traditional methods, improves the synthesis efficiency, and can synthesize a high-entropy oxide positive electrode material in a very short time.

[0034] Furthermore, the laser synthesis method provided by the present invention can bring about instantaneous high heat, thereby melting various metals or metal salts, increasing the disorder of various metals, and successfully synthesizing high entropy oxides.

[0035] Furthermore, when the high-entropy oxide prepared by the synthesis method provided by the present invention is used to prepare the positive electrode material, the multi-component transition metal ions in the positive electrode material can regulate the local structure during the sodium ion insertion / extraction process, thereby delaying the phase transition and making it highly reversible. The material exhibits excellent rate and cycle performance. At a charge and discharge rate of 3C, the reversible capacity after 500 cycles is still as high as over 90%.

[0036] Furthermore, the present invention introduces high entropy chemistry into the design of positive electrode materials, providing a new technical approach for the further development of new sodium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Flowchart of a method for preparing a high entropy oxide according to an embodiment of the present invention;

[0038] Figure 2 This is a transmission electron microscope (TEM) image of the high entropy oxide of Example 1 of the present invention;

[0039] Figure 3 This is a scanning electron microscope (SEM) image of the high entropy oxide of Example 1 of the present invention;

[0040] Figure 4 This is the sodium storage cycle performance of the high entropy oxide of Example 1 of the present invention. DETAILED DESCRIPTION

[0041] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below with reference to embodiments. It should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0042] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0043] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside", and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0044] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0045] See also Figure 1 , which is a flow chart of a method for preparing a high entropy oxide according to an embodiment of the present invention. An embodiment of the present invention provides a method for preparing a high entropy oxide, comprising:

[0046] Weigh the metal powders of each component in molar ratio, including sodium, nickel, magnesium, copper, iron, manganese, titanium and tin;

[0047] Grinding the metal powders in a mortar to uniformly mix the metal powders;

[0048] Pressing the uniformly mixed metal powder into a multi-metal mixed tablet;

[0049] A laser sputtering synthesis device is used to treat a multi-metal mixed pellet placed in a preset atmosphere by a laser sputtering method, and a line scan is performed in a scanning area with a line spacing of 0.001 mm for a set time, and then the sputtered high entropy oxide powder is collected on a substrate;

[0050] The metal powder includes metal elements, metal salts, metal oxides, metal chlorides and metal nitrates. The chemical formula of high entropy oxide powder is NaNi 0.25 Mg 0.05 Cu 0.1 Fe 0.2 Mn 0.2 Ti 0.1 Sn 0.1O2 O2;

[0051] The molar ratio of the metal elements in each metal powder is:

[0052] Na: Ni: Mg: Cu: Fe: Mn: T i: Sn=1: 0.25: 0.05: 0.1: 0.2: 0.2: 0.1: 0.102;

[0053] The preset atmosphere includes oxygen, argon, nitrogen, air and argon-hydrogen mixture;

[0054] The heat source used in the laser sputtering method is a fiber laser.

[0055] It can be understood that the mass ratio of the eight metal elements is: Na:Ni:Mg:Cu:Fe:Mn:Ti:Sn=11:7:0.6:2.9:5.2:5:2.2:5.1.

[0056] Specifically, the pressing process includes using a cold isostatic press to press the uniformly mixed metal powder into tablets;

[0057] The tableting pressure was set to 0.5 KPa, and the tableting time was set to 5 s to 10 s.

[0058] Specifically, the laser power used in the laser sputtering process is in the range of 10% to 100%, and the scanning rate is in the range of 100 to 2000 mm / s.

[0059] In practice, the laser power settings include 10% and 100%, and the line scanning speeds include 100 mm / s and 2000 mm / s. The settings of the laser power and the line scanning speed have no mutual influence, that is, the laser power and the line scanning speed can be set separately based on experience.

[0060] Preferably, the laser power is 70% and the scanning speed is 150 mm / s.

[0061] Specifically, a pigment tracer is added to a mortar containing the metal powder, and the tracer and the metal powder are mixed uniformly, so as to judge whether the metal powder is mixed uniformly by the color uniformity of the color tracer in the metal powder.

[0062] It is understood that the pigment tracer is a pigment that is different in color from the metal powder and is easy to observe, such as red or blue pigment.

[0063] In practice, the particle size of the tracer is equal to or similar to that of the metal powder to ensure uniform mixing; the mass ratio of the tracer powder to all metal powders is 1:50.

[0064] Specifically, after the tableting density is determined by the thickness of the multi-metal mixed tableting, the compactness of the tableting is judged according to the tableting density, and whether secondary tableting is required is determined according to the compactness.

[0065] It is understood that the compactness of the tablet is proportional to the tablet density, that is, the greater the tablet density, the tighter the tablet:

[0066] When the compaction degree is greater than or equal to the standard compaction degree, that is, the tableting density is greater than or equal to the standard density, the multi-metal mixed tableting does not require secondary tableting;

[0067] When the compaction degree is less than the standard compaction degree, that is, the tableting density is less than the standard density, the multi-metal mixed tableting needs to be subjected to secondary tableting.

[0068] In practice, the standard density is 5g / cm 3 , the tablet density is calculated by the following formula:

[0069] Wherein, m is the total mass of the metal powder and tracer powder to be tableted, h is the thickness of the tablet after tableting, and r is the inner radius of the circular tableting die.

[0070] Therefore, when the tablet density is ≥5g / cm 3 When the tablet density is less than 5g / cm 3 When the tablet is pressed twice, the tablet density should be ≥5g / cm 3 .

[0071] Specifically, the composition of the preset atmosphere is determined according to the oxygen content of the metal powder during the laser sputtering process;

[0072] If the oxygen content in the metal powder is lower than the minimum oxygen content, it is determined that the preset atmosphere needs to contain oxygen;

[0073] The minimum oxygen content is twice the amount of Na atoms.

[0074] It can be understood that: (1) if eight pure metal powders of sodium, nickel, magnesium, copper, iron, manganese, titanium and tin are taken, the metal powders do not contain oxygen atoms, so the oxygen content in the metal powders is lower than the minimum oxygen content, and the preset atmosphere during laser sputtering is a mixed gas containing oxygen, and the mixed gas must include oxygen and at least one inert gas; (2) if eight metal oxides or metal salt powders of sodium, nickel, magnesium, copper, iron, manganese, titanium and tin are taken, the metal powders already contain oxygen atoms, so it is necessary to determine the relationship between the oxygen content in the metal powders and the minimum oxygen content. When the oxygen content is less than When the oxygen content is the lowest, the preset atmosphere during laser sputtering is also a mixed gas containing oxygen, and the mixed gas must include oxygen and at least one inert gas; (3) If oxides or metal salt powders of eight metals, namely sodium, nickel, magnesium, copper, iron, manganese, titanium and tin, are taken, and the relationship between the oxygen content in the metal powder and the lowest oxygen content is determined to be: oxygen content ≥ lowest oxygen content, the preset atmosphere during laser sputtering can be a mixed gas composed of several inert gases, or a pure inert gas, or a mixed gas containing oxygen, and the mixed gas must include oxygen and at least one inert gas.

[0075] In practice, preferably, an argon mixture containing 5% oxygen is used.

[0076] Specifically, the crystal consistency of the high entropy oxide is determined based on the roughness of the high entropy oxide powder on the substrate surface, and the substrate temperature during laser sputtering is adjusted based on the crystal consistency.

[0077] Since it is necessary to obtain the roughness of the substrate surface, it is understood that the laser sputtering synthesis equipment is equipped with an image analysis device, including:

[0078] An image capturing unit is provided inside the laser sputtering synthesis device to obtain an actual roughness image of the substrate surface after the high entropy oxide powder is sputtered;

[0079] An image processing unit connected to the image capturing unit is used to receive the actual roughness image, convert it into grayscale, and perform noise reduction processing using a median filter to obtain a processed roughness image;

[0080] The image comparison unit compares the roughness of the processed roughness image with the roughness of a series of pre-stored standard roughness images to determine between which two groups of standard roughness images the roughness of the processed roughness image falls, that is, to determine the roughness range of the actual roughness image, and then matches the roughness range with the roughness image corresponding to the standard roughness range, and determines the crystal consistency of the current high entropy oxide powder sputtered on the substrate surface according to the crystal consistency corresponding to the standard roughness image.

[0081] If the crystal consistency result shows that the high entropy oxide powder sputtered on the substrate surface is crystalline, there is no need to change the current substrate temperature;

[0082] If the result of crystal consistency is that the high entropy oxide powder sputtered on the substrate surface is an amorphous structure, the temperature of the substrate needs to be increased.

[0083] Specifically, the method for determining the crystal consistency of the high entropy oxide according to the roughness of the high entropy oxide powder on the substrate surface includes:

[0084] Acquiring a roughness image of the high entropy oxide powder on a substrate surface;

[0085] comparing the roughness of the roughness image with the roughness of several standard roughness images to determine the crystal consistency of the high entropy oxide;

[0086] The determination result of the crystal consistency includes crystal and amorphous structures.

[0087] It is understandable that before using the laser sputtering method to prepare the high-entropy oxide, the laboratory had prepared a series of samples of the high-entropy oxide using a non-laser sputtering method. Each sample corresponds to a different crystal structure and therefore has a different standard roughness image, and each standard roughness image corresponds to a different standard roughness value.

[0088] The standard roughness image includes a crystalline standard roughness image and an amorphous standard roughness image.

[0089] Specifically, the substrate temperature during laser sputtering is adjusted according to the crystal consistency determination result:

[0090] When the crystal consistency of the high entropy oxide powder on the surface of the substrate is an amorphous structure, the adjusted substrate temperature is determined based on the ratio of the current roughness value corresponding to the current roughness image to the standard roughness value corresponding to the standard roughness image and the current substrate temperature.

[0091] In implementation, when the crystal consistency of the high entropy oxide powder on the centralized procurement surface is an amorphous structure, the adjusted substrate temperature is determined based on the ratio of the current roughness value corresponding to the current roughness image to the crystal standard roughness value corresponding to the crystal standard roughness image and the current substrate temperature.

[0092] It can be understood that after determining which two sets of standard roughness images the roughness of the processed roughness image falls between, the roughness value range of the processed roughness image can be determined, that is, the roughness value range between the two sets of standard roughness images.

[0093] The adjusted substrate temperature is:

[0094] Wherein, k is the temperature coefficient (1≤k<1.1), T0 is the current substrate temperature, D1 is the maximum roughness value of the currently processed roughness image, and D0 is the crystal standard roughness value.

[0095] For example, a series of standard roughness images are recorded as x1, x2, x3, ..., x10, and the corresponding roughness values are y1, y2, y3, ..., y10, where x7 to x10 are all crystalline standard roughness images, and the remaining are amorphous standard roughness images; the roughness of the currently processed roughness image is between the standard roughness image x3 and the standard roughness image x4, that is, the roughness value range of the currently processed roughness image is (y4, y3); therefore, the crystal consistency of the high-entropy oxide powder on the substrate surface is amorphous, and the substrate temperature needs to be increased. The adjusted substrate temperature is T = k × T0 × y3 / y7. In this embodiment, k = 1.03.

[0096] The embodiment of the present invention further provides a positive electrode material, wherein the active material of the positive electrode material is the high entropy oxide prepared by the laser sputtering method in Example 1.

[0097] In practice, the process of preparing the positive electrode material using high entropy oxide is as follows:

[0098] After mixing high-entropy oxide, conductive carbon black, and a binder (PVDF) in a mass ratio of 8:1:1, an appropriate amount of N-methyl-2-pyrrolidone was added as a dispersant to form a non-fluid paste slurry. The mixture was then stirred three times in a high-speed mixer. Once the slurry was uniformly stirred, it was evenly coated onto cut aluminum foil using a doctor blade to a thickness of 90 μm. The film was then dried at 60°C for 1 hour and then placed in a vacuum drying oven at 120°C for 10 hours. The positive electrode sheets were then cut using a microtome to obtain 14 mm diameter positive electrodes.

[0099] The experiment used a CR2032 button-type half-cell, with metallic sodium as the counter electrode and Celgard 2700 polypropylene as the separator. 1 mol / L NaClO4 was dissolved in a 1:1 volume ratio of EC / DEC (ethylene carbonate / diethyl carbonate) as the electrolyte. The CR2032 button-type cell was assembled in a glove box filled with an argon atmosphere. Finally, the assembled cell was left to stand for 5 hours before its electrochemical performance was studied.

[0100] Example 1:

[0101] See also Figure 2 and Figure 3 As shown, they are respectively a transmission electron microscope (TEM) image of the high entropy oxide of Example 1 of the present invention and a scanning electron microscope (SEM) image of the high entropy oxide.

[0102] Step S1, weighing 110 g of sodium metal powder, 70 g of nickel metal powder, 6 g of magnesium metal powder, 29 g of copper metal powder, 52 g of iron metal powder, 50 g of manganese metal powder, 22 g of titanium metal powder and 51 g of tin metal powder according to the mass ratio of 11:7:0.6:2.9:5.2:5:2.2:5.1, and then weighing 7.8 g of red tracer;

[0103] Step S2, grinding the eight metal powders and the tracer in a mortar, and determining whether the mixture is uniform by the tracer, and stopping the grinding when the mixture is uniform;

[0104] Step S3, pressing the uniformly mixed powder into tablets using a cold isostatic press, wherein the tableting pressure is set to 0.5 kPa, the tableting time is set to 10 seconds, and the tablets are round tablets with a bottom diameter of 14 cm. After two tabletings at the same tableting pressure and tableting time, the tablet density is less than the standard density;

[0105] Step S4, using a laser sputtering synthesis equipment to treat a multi-metal mixed tablet placed in an argon mixture containing 5% oxygen by laser sputtering method (laser power of 70%, scanning speed of 150 mm / s), and collecting the sputtered high entropy oxide powder on the substrate after line scanning with a line spacing of 0.001 mm in the scanning area for 1 hour, wherein the laser sputtering pressure is 15 kPa and the substrate temperature is 600°C.

[0106] Step S5, preparing the positive electrode material using high entropy oxide:

[0107] After mixing high-entropy oxide, conductive carbon black, and a binder (PVDF) in a mass ratio of 8:1:1, an appropriate amount of N-methyl-2-pyrrolidone was added as a dispersant to form a non-fluid paste slurry. The mixture was then stirred three times in a high-speed mixer. Once the slurry was uniformly stirred, it was evenly coated onto cut aluminum foil using a doctor blade to a thickness of 90 μm. The film was then dried at 60°C for 1 hour and then placed in a vacuum drying oven at 120°C for 10 hours. The positive electrode sheets were then cut using a microtome to obtain 14 mm diameter positive electrodes.

[0108] like Figure 4 As shown, this shows the sodium storage cycle performance of the high-entropy oxide of Example 1 of the present invention. This experiment used a CR2032 button-type half-cell with metallic sodium as the counter electrode, Celgard 2700 polypropylene as the separator, and 1 mol / L NaClO4 dissolved in a 1:1 volume ratio of EC / DEC (ethylene carbonate / diethyl carbonate) as the electrolyte. The CR2032 button-type cell was assembled in an argon-filled glove box. Finally, the assembled cell was left to rest for 5 hours before its electrochemical performance was studied in a blue-electric test system.

[0109] like Figure 4 It can be seen that when the high entropy oxide NaNi is obtained using the method provided in Example 1 0.25 Mg 0.05 Cu 0.1 Fe 0.2 Mn 0.2 Ti 0.1 Sn 0.1O2 When the positive electrode material is prepared by O2, its charge-discharge specific capacity is still greater than 90mAh / g after 500 cycles at a 3C rate, and its coulombic efficiency is close to 100%, indicating that the high-entropy oxide prepared by this method has excellent electrochemical performance when used as a positive electrode material.

[0110] Example 2:

[0111] The difference between Example 2 and Example 1 is that in step S4, a laser sputtering synthesis device is used to process the multi-metal mixed tablet by laser sputtering (laser power is 70%, scanning speed is 150 mm / s) in a pure argon atmosphere; the remaining steps are the same as in Example 1.

[0112] Example 3:

[0113] The difference between Example 3 and Example 1 is that no tracer is added in step S2 to determine whether the grinding is uniform, and the grinding time is 15 minutes; the remaining steps are the same as Example 1.

[0114] Example 4:

[0115] The difference between Example 4 and Example 1 is that in step S3 the tableting time is 10 s, and the relationship between the tableting density and the standard density is not determined; the remaining steps are the same as in Example 1.

[0116] The sodium storage cycle performance of the high entropy oxides prepared in Examples 1 to 4 was tested by 500 cycles of charge and discharge at a 3C rate. The test results are shown in Table 1.

[0117] Table 1

[0118]

[0119] It can be seen from Table 1 that the NaNi 0.25 Mg 0.05 Cu 0.1 Fe 0.2 Mn 0.2 Ti 0.1 Sn 0.1O2 When O2 is used as the active material of the positive electrode material, the electrochemical performance is the best. The charge and discharge capacity is the largest after 500 cycles at a 3C rate, reaching more than 90mAh / g.

[0120] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

[0121] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a high entropy oxide, characterized in that: include: Weigh the metal powders of each component in molar ratio, including sodium, nickel, magnesium, copper, iron, manganese, titanium and tin; Grinding the metal powders in a mortar to uniformly mix the metal powders; Pressing the uniformly mixed metal powder into a multi-metal mixed tablet; A laser sputtering synthesis device is used to treat a multi-metal mixed pellet placed in a preset atmosphere by a laser sputtering method, and a line scan is performed in a scanning area with a line spacing of 0.001 mm for a set time, and then the sputtered high entropy oxide powder is collected on a substrate; Wherein, the metal powder includes metal elements, metal salts and metal oxides; The molar ratio of the metal elements in each of the metal powders is: Na: Ni: Mg: Cu: Fe: Mn: Ti: Sn=1: 0.25: 0.05: 0.1: 0.2: 0.2: 0.1: 0.102; The preset atmosphere includes oxygen, argon, nitrogen, air and argon-hydrogen mixture; The heat source used in the laser sputtering method is a fiber laser; The crystal consistency of the high entropy oxide is determined according to the roughness of the high entropy oxide powder on the substrate surface, and the substrate temperature during laser sputtering is adjusted according to the crystal consistency, wherein: If the crystal consistency result shows that the high entropy oxide powder sputtered on the substrate surface is crystalline, there is no need to change the current substrate temperature; If the crystal consistency result shows that the high entropy oxide powder sputtered on the substrate surface is an amorphous structure, the substrate temperature needs to be increased; The method for determining the crystal consistency of the high entropy oxide according to the roughness of the high entropy oxide powder on the surface of the substrate includes: Acquiring a roughness image of the high entropy oxide powder on a substrate surface; comparing the roughness of the roughness image with the roughness of several standard roughness images to determine the crystal consistency of the high entropy oxide; Wherein, the determination result of the crystal consistency includes crystal and amorphous structures; Adjust the substrate temperature during laser sputtering according to the crystal consistency determination result: When the crystal consistency of the high entropy oxide powder on the surface of the substrate is an amorphous structure, the adjusted substrate temperature is determined based on the ratio of the current roughness value corresponding to the current roughness image to the standard roughness value corresponding to the standard roughness image and the current substrate temperature.

2. The method for preparing a high entropy oxide according to claim 1, wherein: The pressing process includes using a cold isostatic pressing machine to press the uniformly mixed metal powder into tablets.

3. The method for preparing a high entropy oxide according to claim 1, wherein: The laser power used in the laser sputtering process ranges from 10% to 100%, and the scanning rate ranges from 100 mm / s to 2000 mm / s.

4. The method for preparing a high entropy oxide according to claim 1, wherein: A pigment tracer is added to the mortar containing the metal powder, and the tracer and the metal powder are mixed evenly, so as to judge whether the metal powder is mixed evenly by the color uniformity of the color tracer in the metal powder.

5. The method for preparing a high entropy oxide according to claim 1, wherein: After the tableting density is determined by the thickness of the multi-metal mixed tableting, the compactness of the tableting is judged according to the tableting density, and whether secondary tableting is required is determined according to the compactness.

6. The method for preparing a high entropy oxide according to claim 1, wherein: determining the composition of the preset atmosphere according to the oxygen content of the metal powder during the laser sputtering process; If the oxygen content in the metal powder is lower than the minimum oxygen content, it is determined that the preset atmosphere needs to contain oxygen; The minimum oxygen content is twice the amount of Na atoms.

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