Sodium tungstate-magnesium tungstate composite coating layer modified O-phase sodium ion battery positive electrode material and preparation method thereof

Abstract

The invention discloses an O-phase sodium ion battery positive electrode material modified by a sodium tungstate-magnesium tungstate composite coating layer and a preparation method of the O-phase sodium ion battery positive electrode material. Relates to the technical field of sodium-ion battery materials. According to the preparation method, an in-situ coating strategy is adopted, the raw materials capable of reacting with the sodium compound are added, residual alkali on the surface of the material is consumed, meanwhile, a stable and uniform coating layer is formed on the surface of the material, and the prepared O-phase sodium ion battery positive electrode material has excellent electrochemical performance; a tungsten-containing compound and a magnesium-containing compound are added in the secondary sintering process, the tungsten-containing compound and the magnesium-containing compound form magnesium tungstate in the sintering process, and meanwhile, the tungsten-containing compound and a sodium source on the surface of the material form sodium tungstate; a double-coating layer formed by magnesium tungstate and sodium tungstate prevents the material from being in contact with an electrolyte, reduces side reaction and improves the cycling stability, and meanwhile, sodium tungstate is preferentially decomposed in the primary cycle of the battery and serves as a sodium supplementing agent, so that the first effect of the material is remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sodium ion battery materials, in particular to an O-phase sodium ion battery positive electrode material modified by a sodium tungstate-magnesium tungstate composite coating layer and a preparation method thereof. BACKGROUND

[0002] In recent years, sodium ion batteries have become an important complementary technology for lithium ion batteries due to their abundant resources and low cost. Layered oxide positive electrode materials are considered as one of the most promising positive electrode systems due to their open two-dimensional sodium ion diffusion channels and high theoretical capacity. Among them, the O-phase sodium ion battery positive electrode material mainly refers to the O3-type layered oxide positive electrode material, which is a kind of layered oxide and has attracted much attention due to its high capacity, good cycle performance and high energy density. The O3-type positive electrode material is usually composed of transition metals (such as Ni, Co, Mn, Fe, etc.) and oxygen elements, and its crystal structure is a layered octahedral stacking form, each octahedral unit is composed of one transition metal ion and six oxygen ions. This structure can accommodate sodium ions and realize reversible sodium ion intercalation / deintercalation during charging and discharging. Due to the high initial sodium content of O3-type materials, their theoretical specific capacity is high, which can reach more than 160 mAh / g; they exhibit good structural stability during cycling, especially high stability in air, which enables them to maintain a long service life in practical applications.

[0003] Although the O3-type positive electrode material has a high theoretical specific capacity and is suitable for application in the power battery market, it has been widely studied in the early stage of sodium batteries. However, due to its high sodium ratio, the content of residual sodium compounds on the surface of the material is high, which brings great challenges to the later application of the material. At present, the coating method can effectively reduce the residual alkali on the surface of the O3-type material, but there are problems of uneven coating and introduction of other impurities. SUMMARY

[0004] The present application provides an O-phase sodium ion battery positive electrode material modified by a sodium tungstate-magnesium tungstate composite coating layer and a preparation method thereof, to solve the problems of high residual alkali on the surface of the O3-type layered oxide positive electrode material and uneven surface coating.

[0005] The object of the present application can be achieved by the following technical solutions: A preparation method of an O-phase sodium ion battery positive electrode material modified by a sodium tungstate-magnesium tungstate composite coating layer, comprising the following steps: S1. uniformly mixing nickel oxide, diiron trioxide, trimanganese tetraoxide and sodium carbonate by ball milling, and obtaining a precursor material by first sintering; S2. After the precursor material, tungsten oxide and magnesium oxide are mixed by ball milling, a sodium tungstate-magnesium tungstate composite coating layer modified O-phase sodium ion battery positive electrode material is obtained by second sintering, crushing and sieving.

[0006] As a further scheme of the present application, in S1, the sodium carbonate, nickel oxide, diiron trioxide and trimanganese tetraoxide are weighed according to the element molar ratio of Na:Ni:Fe:Mn=1.01:0.33:0.33:0.33.

[0007] As a further scheme of the present application, in S1, the first sintering temperature is 800-1000℃.

[0008] As a further scheme of the present application, in S1, the first sintering time is 10-15h.

[0009] As a further scheme of the present application, in S2, the addition amount of tungsten oxide is 0.1-0.5% of the mass of the precursor material.

[0010] As a further scheme of the present application, in S2, the addition amount of magnesium oxide is 0.05-0.5% of the mass of the precursor material.

[0011] As a further scheme of the present application, in S2, the mass ratio of tungsten oxide to magnesium oxide is (1-3):1.

[0012] As a further scheme of the present application, in S2, the second sintering temperature is 500-800℃.

[0013] As a further scheme of the present application, in S2, the second sintering time is 10-15h.

[0014] As a further scheme of the present application, the ball milling rotation speed is 400-800r / min.

[0015] A sodium tungstate-magnesium tungstate composite coating layer modified O-phase sodium ion battery positive electrode material is prepared by the above preparation method.

[0016] Compared with the prior art, the present application has the following beneficial effects: The application provides a sodium tungstate-magnesium tungstate composite coating modified O-phase sodium ion battery positive electrode material and a preparation method thereof. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2@MW prepared in Example 1 of the application is shown in the scanning electron microscope (SEM) image. Figure 2 The Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2 prepared in Comparative Example 1 of the application is shown in the scanning electron microscope image. Figure 3 The particle size distribution of the Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2@MW prepared in Example 1 of the application is shown in the particle size distribution graph. Figure 4 The charge-discharge curve of the Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2@MW prepared in Example 1 of the application is shown in the charge-discharge curve graph. Figure 5 The cycle performance comparison of the Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2@MW prepared in Example 1 of the application and the Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2 prepared in Comparative Example 1 of the application is shown in the cycle performance comparison graph. DETAILED DESCRIPTION

[0018] The specific embodiments of the present application are described below in detail, but it should be understood that the scope of protection of the present application is not limited by the specific embodiments.

[0019] The terms used in the embodiments of the present application are merely for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0020] It should be understood that in various embodiments of the present application, the size of the sequence number of each process does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0021] The weight of the related components mentioned in the embodiments of the present application can not only refer to the specific content of each component, but also represent the weight ratio between each component, therefore, as long as the content of the related components in the embodiments of the present application is enlarged or reduced in proportion, it is within the scope disclosed in the embodiments of the present application. Specifically, the mass mentioned in the embodiments of the present application can be μg, mg, g, kg and other mass units commonly known in the chemical field.

[0022] Unless otherwise defined, all professional terms used below have the same meaning as generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present application.

[0023] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0024] In a first aspect, the embodiments of the present application provide a preparation method of an O-phase sodium-ion battery positive electrode material modified by a sodium tungstate-magnesium tungstate composite coating layer, specifically, comprising the following steps: S1. uniformly mixing nickel oxide, diiron trioxide, trimanganese tetraoxide and sodium carbonate by ball milling, and obtaining a precursor material by first sintering; S2. ball milling the precursor material, tungsten oxide and magnesium oxide, and obtaining the O-phase sodium-ion battery positive electrode material modified by the sodium tungstate-magnesium tungstate composite coating layer by second sintering, crushing and sieving.

[0025] In a specific embodiment, sodium carbonate, nickel oxide, diiron trioxide and trimanganese tetraoxide are weighed according to the element molar ratio of Na:Ni:Fe:Mn=1.01:0.33:0.33:0.33.

[0026] In a specific implementation case, the first sintering temperature is 800-1000℃; the first sintering time is 10-15h; wherein the first sintering temperature includes, but is not limited to, 800℃, 820℃, 840℃, 860℃, 880℃, 900℃, 920℃, 940℃, 960℃, 980℃, and 1000℃; and the first sintering time includes, but is not limited to, 10h, 11h, 12h, 13h, 14h, and 15h.

[0027] Nickel oxide (NiO) and ferric oxide (F) ), manganese tetroxide (M ) and sodium carbonate (N C The raw materials are mixed in a certain proportion and then ball-milled to ensure thorough and uniform mixing. Ball milling is a physical mixing method under mechanical force, which can improve the dispersibility and uniformity of the raw materials, thus laying the foundation for subsequent chemical reactions. The ball-milled mixture undergoes a first sintering treatment, followed by a solid-state reaction at high temperature to generate a preliminary O-phase layered cathode material. This process involves lattice reconstruction of the metal oxide and the insertion of sodium ions, forming a stable O-type structure. The resulting precursor material has the chemical formula Na. 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2.

[0028] In a specific implementation case, the amount of tungsten oxide added is 0.1-0.5% of the precursor material mass; including but not limited to 0.1%, 0.2%, 0.3%, 0.4%, and 0.5%.

[0029] In a specific implementation case, the amount of magnesium oxide added is 0.05-0.5% of the precursor material mass; including but not limited to 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, and 0.5%.

[0030] In a specific implementation case, the mass ratio of tungsten oxide to magnesium oxide is (1-3):1; including but not limited to 1:1, 2:1, and 3:1.

[0031] In a specific implementation case, the second sintering temperature is 500-800℃; the second sintering time is 10-15h; wherein the second sintering temperature includes, but is not limited to, 500℃, 520℃, 540℃, 560℃, 580℃, 600℃, 620℃, 640℃, 660℃, 680℃, 700℃, 720℃, 740℃, 760℃, 780℃, and 800℃; and the first sintering time includes, but is not limited to, 10h, 11h, 12h, 13h, 14h, and 15h.

[0032] In a specific embodiment, the ball milling rotation speed is 400-800 r / min; including but not limited to 400 r / min, 500 r / min, 600 r / min, 700 r / min, 800 r / min.

[0033] In the precursor material, tungsten oxide (WO3) and magnesium oxide (MgO) are added, and ball milling is performed again to ensure that the components are fully mixed. Then, second sintering is performed to form a uniform coating layer of sodium tungstate (NaWO4) and magnesium tungstate (MgWO4). This process promotes the formation of tungstate through high-temperature calcination and uniformly coats the surface of the positive electrode material as a coating layer; the tungstate coating layer can effectively inhibit the volume expansion of the positive electrode material during charging and discharging, while reducing the occurrence of side reactions, thereby improving the overall performance of the battery. The chemical formula of the O-phase sodium-ion battery positive electrode material modified by the sodium tungstate-magnesium tungstate composite coating layer prepared finally is Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O 2@ MW.

[0034] In a second aspect, the present application provides a sodium tungstate-magnesium tungstate composite coating layer modified O-phase sodium-ion battery positive electrode material prepared by the preparation method of the first aspect.

[0035] The following will be further illustrated with specific examples.

[0036] Example 1

[0037] A preparation method of a sodium tungstate-magnesium tungstate composite coating layer modified O-phase sodium-ion battery positive electrode material, comprising the following steps: S1. 45 g of nickel oxide, 48 g of ferric sesquioxide, 45 g of trimanganese tetroxide, and 96 g of battery-grade sodium carbonate are added to a ball milling tank, and after uniform ball milling mixing at a rotation speed of 600 r / min, they are poured into a sagger, and then the sagger is placed in an atmosphere furnace and heated at a rate of 3 ℃ / min from room temperature to a first sintering temperature of 900 ℃ for first sintering, the sintering atmosphere is air, the first sintering time is 15 h, and after the end, it is naturally cooled to room temperature to obtain a precursor material, the chemical formula of which is Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2; S2. Take 100 g of precursor material, 0.1 g of tungsten oxide and 0.1 g of magnesium oxide, add them to the ball mill tank, mix uniformly at a speed of 600 r / min, then pour into the crucible, heat from room temperature to a second sintering temperature of 700℃ at a rate of 3℃ / min in an atmosphere furnace, the sintering atmosphere is air, the second sintering time is 10h, and then naturally cool to room temperature, crush and sieve to obtain a sodium tungstate-magnesium tungstate composite coating modified O-phase sodium ion battery positive electrode material, the chemical formula is Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2@MW.

[0038] Example 2

[0039] A preparation method of a sodium tungstate-magnesium tungstate composite coating modified O-phase sodium ion battery positive electrode material, comprising the following steps: S1. The same as example 1; S2. Take 100 g of precursor material, 0.14 g of tungsten oxide and 0.07 g of magnesium oxide, add them to the ball mill tank, mix uniformly at a speed of 600 r / min, then pour into the crucible, heat from room temperature to a second sintering temperature of 700℃ at a rate of 3℃ / min in an atmosphere furnace, the sintering atmosphere is air, the second sintering time is 10h, and then naturally cool to room temperature, crush and sieve to obtain a sodium tungstate-magnesium tungstate composite coating modified O-phase sodium ion battery positive electrode material, the chemical formula is Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2@MW.

[0040] Example 3

[0041] A preparation method of a sodium tungstate-magnesium tungstate composite coating modified O-phase sodium ion battery positive electrode material, comprising the following steps: S1. The same as example 1; S2. Take 100 g of precursor material, 0.15 g of tungsten oxide and 0.05 g of magnesium oxide, add them to the ball mill tank, mix uniformly at a speed of 600 r / min, then pour into the crucible, heat from room temperature to a second sintering temperature of 700℃ at a rate of 3℃ / min in an atmosphere furnace, the sintering atmosphere is air, the second sintering time is 10h, and then naturally cool to room temperature, crush and sieve to obtain a sodium tungstate-magnesium tungstate composite coating modified O-phase sodium ion battery positive electrode material, the chemical formula is Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2@MW.

[0042] Example 4

[0043] A preparation method of an O-phase sodium-ion battery positive electrode material modified by a sodium tungstate-magnesium tungstate composite coating layer, comprising the following steps: S1. The same as example 1; S2. Take 100g of the precursor material, 0.5g of tungsten oxide and 0.5g of magnesium oxide, add them into the ball mill tank, mix uniformly at a speed of 600r / min, then pour into the sagger, heat from room temperature to a second sintering temperature of 700℃ at a rate of 3℃ / min in an atmosphere furnace, the sintering atmosphere is air, the second sintering time is 10h, and then naturally cool to room temperature after the end of the second sintering, crush and sieve to obtain the O-phase sodium-ion battery positive electrode material modified by the sodium tungstate-magnesium tungstate composite coating layer, the chemical formula is Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2@MW.

[0044] Example 5

[0045] A preparation method of an O-phase sodium-ion battery positive electrode material modified by a sodium tungstate-magnesium tungstate composite coating layer, comprising the following steps: S1. The same as example 1; S2. Take 100g of the precursor material, 0.5g of tungsten oxide and 0.25g of magnesium oxide, add them into the ball mill tank, mix uniformly at a speed of 600r / min, then pour into the sagger, heat from room temperature to a second sintering temperature of 700℃ at a rate of 3℃ / min in an atmosphere furnace, the sintering atmosphere is air, the second sintering time is 10h, and then naturally cool to room temperature after the end of the second sintering, crush and sieve to obtain the O-phase sodium-ion battery positive electrode material modified by the sodium tungstate-magnesium tungstate composite coating layer, the chemical formula is Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2@MW.

[0046] Example 6

[0047] A preparation method of an O-phase sodium-ion battery positive electrode material modified by a sodium tungstate-magnesium tungstate composite coating layer, comprising the following steps: S1. The same as example 1; S2. Weigh 100g of precursor material, 0.2g of tungsten oxide, and 0.2g of magnesium oxide, add them to a ball mill jar, and ball mill at 600r / min until uniformly mixed. Pour the mixture into a crucible and sinter it in an atmosphere furnace from room temperature to a second sintering temperature of 700℃ at a rate of 3℃ / min. The sintering atmosphere is air, and the second sintering time is 10h. After sintering, allow it to cool naturally to room temperature, pulverize, and sieve to obtain an O-phase sodium-ion battery cathode material modified with a sodium tungstate-magnesium tungstate composite coating, with the chemical formula Na. 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2@MW.

[0048] Comparative Example 1

[0049] A method for preparing an O-phase sodium-ion battery cathode material includes the following steps: 45g of nickel oxide, 48g of ferric oxide, 45g of manganese tetroxide, and 96g of battery-grade sodium carbonate were added to a ball mill jar and mixed evenly at 600 rpm. The mixture was then poured into a crucible and subjected to a first sintering in an atmosphere furnace, with the temperature increased from room temperature to 900℃ at a rate of 3℃ / min. The first sintering was carried out in an air atmosphere for 15 hours. After sintering, the mixture was allowed to cool naturally to room temperature to obtain an O3-phase sodium-ion battery cathode material with the chemical formula Na. 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2.

[0050] Comparative Example 2

[0051] A method for preparing an O-phase sodium-ion battery cathode material includes the following steps: S1. Same as Example 1; S2. Weigh 100g of precursor material and 0.2g of tungsten oxide, add them to a ball mill jar, and ball mill them evenly at 600r / min. Pour the mixture into a crucible and sinter it in an atmosphere furnace at a rate of 3℃ / min from room temperature to a second sintering temperature of 700℃. The sintering atmosphere is air, and the second sintering time is 10h. After sintering, allow it to cool naturally to room temperature, pulverize, and sieve to obtain the O-phase sodium-ion battery cathode material with the chemical formula Na. 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2@W.

[0052] Comparative Example 3

[0053] A method for preparing an O-phase sodium-ion battery cathode material includes the following steps: S1. Same as Example 1; S2. 100 g of the precursor material, 0.2 g of magnesium oxide were weighed and added into a ball mill tank. After being uniformly mixed by ball milling at a rotation speed of 600 r / min, they were poured into a crucible and subjected to a second sintering at a second sintering temperature of 700 ℃ at a rate of 3 ℃ / min from room temperature in an atmosphere furnace, the sintering atmosphere was air, the second sintering time was 10 h, and after the end, it was naturally cooled to room temperature. The O-phase sodium-ion battery positive electrode material modified by a sodium tungstate-magnesium tungstate composite coating layer was obtained by crushing and sieving, and the chemical formula was Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2@M.

[0054] Comparative Example 4

[0055] A preparation method of an O-phase sodium-ion battery positive electrode material modified by a sodium tungstate-magnesium tungstate composite coating layer, comprising the following steps: S1. The same as Example 1; S2. 100 g of the precursor material, 0.1 g of tungsten oxide and 0.2 g of magnesium oxide were weighed and added into a ball mill tank. After being uniformly mixed by ball milling at a rotation speed of 600 r / min, they were poured into a crucible and subjected to a second sintering at a second sintering temperature of 700 ℃ at a rate of 3 ℃ / min from room temperature in an atmosphere furnace, the sintering atmosphere was air, the second sintering time was 10 h, and after the end, it was naturally cooled to room temperature. The O-phase sodium-ion battery positive electrode material modified by a sodium tungstate-magnesium tungstate composite coating layer was obtained by crushing and sieving, and the chemical formula was Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2@MW.

[0056] Performance test: (1) The products prepared in Example 1 and Comparative Example 1 were subjected to characterization test. The SEM image of Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2@MW prepared in Example 1 was as shown in Figure 1 ; the SEM image of Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2 prepared in Comparative Example 1 was as shown in Figure 2 ; and the particle size distribution graph of Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2@MW prepared in Example 1 was as shown in Figure 3 .

[0057] (2) The amount of tungsten oxide and magnesium oxide used in the preparation process of Examples 1-6 and Comparative Examples 1-4 and the pH test results of the final product are shown in Table 1.

[0058] Table 1

[0059] (3) The products obtained in each of the above Examples 1-6 and Comparative Examples 1-4 were used to make sodium ion batteries, and the battery capacity and cycle performance of each sodium ion battery were electrochemically tested; wherein the O-phase sodium ion battery positive electrode material obtained in the examples and comparative examples was assembled into a button cell using a technical solution well known to those skilled in the art for preparing a lithium ion battery from a positive electrode material; the specific method was as follows: the O-phase sodium ion battery positive electrode material prepared, acetylene black and polyvinylidene fluoride (PVDF) were weighed according to a mass ratio of 90:5:5, mixed uniformly, added with NMP and stirred for 2 h to form a viscous slurry, uniformly coated on an aluminum foil, vacuum baked at 80°C, pressed into a sheet, and the positive electrode sheet with a diameter of 14 mm was cut. A pure sodium sheet with a diameter of 16 mm was used as the negative electrode sheet, ENA-18 (brand: Tianci) was used as the electrolyte, and a PP / PE / PP composite separator was used to assemble a button cell in an argon-filled glove box. The electrochemical tests included first charge-discharge capacity test at 1C and capacity retention rate test after 100 cycles at 45°C. The test results are shown in Table 2.

[0060] Table 2

[0061] The Na 1.01 Ni 0.33 Fe 0.33 Mn 0.33 O2@MW charge-discharge curve is shown in Figure 4 , and the cycle performance of the products prepared in Example 1 and Comparative Example 1 is shown in Figure 5 .

[0062] From the above test, it can be seen that the sodium ion battery assembled by the products prepared in Example 1-Example 6 has stable electrochemical cycle and high capacity retention rate, indicating that the composite doping of tungsten oxide and magnesium oxide can synergistically improve the performance of the battery; compared with Comparative Example 1 and Comparative Example 1, the material in Comparative Example 1 has no further coating of tungsten-containing compounds, resulting in excessive contact of the material with the electrolyte and more side reactions, and its cycle stability is poor; compared with Comparative Example 1 and Comparative Example 2, the mixed oxide (tungsten oxide and magnesium oxide) doped with the two burns is replaced by an equal amount of tungsten oxide, at this time only a single layer of coating layer is formed; on the other hand, due to the lack of magnesium tungstate passivation layer, it is difficult to avoid interface side reactions, and its capacity retention rate is poor; compared with Comparative Example 6 and Comparative Example 1, even in the case of the same amount of tungsten oxide, due to the lack of magnesium oxide, its cycle performance is poor; compared with Comparative Example 1 and Comparative Example 3, when only magnesium oxide is used, the material may be more prone to brittle fracture due to the lack of flexible interface phase (Na2WO4). The composite coating layer can synergistically inhibit particle breakage and interface side reactions, and the long-term cycle capacity retention rate of single magnesium oxide coating decreases; compared with Comparative Example 1 and Comparative Example 4, when the amount of magnesium oxide is excessive, it leads to an excessively thick coating layer, which hinders the diffusion of sodium ions.

[0063] It should be noted that the relational terms herein such as first and second, are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus including a series of elements includes not only those elements, but also other elements not explicitly listed or inherent to such a process, method, article or apparatus.

[0064] The above disclosure is only a few specific embodiments of the present application, but the embodiments of the present application are not limited thereto, and any changes that can be thought of by those skilled in the art should fall within the protection scope of the present application.

Claims

1. A method for preparing an O-phase sodium-ion battery cathode material modified by a sodium tungstate-magnesium tungstate composite coating layer, characterized in that, The method comprises the following steps: S1. uniformly mixing nickel oxide, diiron trioxide, trimanganese tetraoxide and sodium carbonate by ball milling, and obtaining a precursor material by first sintering; S2. mixing the precursor material, tungsten oxide and magnesium oxide by ball milling, and obtaining a sodium tungstate-magnesium tungstate composite coating layer modified O-phase sodium ion battery anode material by second sintering and crushing and sieving.

2. The preparation method of the O-phase sodium-ion battery cathode material modified by the sodium tungstate-magnesium tungstate composite coating layer according to claim 1, characterized in that, In S1, the sodium carbonate, nickel oxide, diiron trioxide and trimanganese tetraoxide are weighed according to the element molar ratio of Na:Ni:Fe:Mn=1.01:0.33:0.33:0.

33.

3. The preparation method of the O-phase sodium-ion battery cathode material modified by the sodium tungstate-magnesium tungstate composite coating layer according to claim 1, characterized in that, In S1, the first sintering temperature is 800-1000℃.

4. The preparation method of the O-phase sodium-ion battery cathode material modified by the sodium tungstate-magnesium tungstate composite coating layer according to claim 1, characterized in that, In S1, the first sintering time is 10-15h.

5. The method for preparing the O-phase sodium-ion battery cathode material modified by sodium tungstate-magnesium tungstate composite coating layer according to claim 1, characterized in that, In S2, the addition amount of the tungsten oxide is 0.1-0.5% of the mass of the precursor material.

6. The method for preparing the O-phase sodium-ion battery cathode material modified by sodium tungstate-magnesium tungstate composite coating layer according to claim 1, characterized in that, In S2, the addition amount of the magnesium oxide is 0.05-0.5% of the mass of the precursor material.

7. The method of claim 1, wherein the method is characterized by: In S2, the mass ratio of the tungsten oxide to the magnesium oxide is (1-3):

1.

8. The method for preparing a sodium tungstate-magnesium tungstate composite coating modified O-phase sodium-ion battery cathode material according to claim 1, characterized in that, In S2, the second sintering temperature is 500-800℃.

9. The method for preparing a sodium tungstate-magnesium tungstate composite coating modified O-phase sodium-ion battery cathode material according to claim 1, characterized in that, In S2, the second sintering time is 10-15h.

10. A sodium tungstate-magnesium tungstate composite coating-modified O-phase sodium-ion battery cathode material, characterized in that, The method is prepared by any one of claims 1-9.

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