Positive electrode material for sodium ion batteries, manufacturing method and use

Abstract

To provide a cathode material for a sodium ion battery and a preparation method thereof such that the residual alkali content on a surface is reduced so that the capacity and rate of the sodium ion battery are at relatively high levels.SOLUTION: The cathode material has a general formula of Na1+aNi1-x-y-zMnxFeyAzO2, where -0.40≤a≤0.25, 0.08<x<0.5, 0.05<y<0.5, and 0.0<z<0.26. A is selected from one of or a combination of two or more of Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B and Cu elements. In the cathode material, at least two diffraction peaks exist when a diffraction angle 2θ value is 42-46°. The diffraction angle 2θ values of the two diffraction peaks are around 43° and around 45°, respectively.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to the technical field of sodium ion batteries, and in particular to positive electrode materials for sodium ion batteries, as well as methods for producing and applications thereof. [Background technology]

[0002] Concerns about the world's lithium resources and the need for new large-scale energy storage applications are driving the constant development of new battery fields. Thanks to the extensive experience with lithium-ion batteries, sodium-ion batteries are experiencing rapid development. Among them, the cathode materials for sodium-ion batteries mainly include layered and tunnel-type transition metal oxides, polyanion compounds, Prussian blue analogues, and organic materials. Along with research into these systems, R&D on sodium-ion batteries is striving for low cost and practical application. In 2011, Komaba et al. in Japan were the first to produce hard carbon ||NaNi 0.5 Mn 0.5 In 2013, Goodenough et al. of the United States proposed a Prussian white cathode material with high voltage and excellent rate characteristics, and in 2014, Hu Yongsheng et al. of China were the first to report on the properties of a layered oxide containing Cu. 3+ / Cu 2+ We discovered the electrochemical activity of redox couples and designed and fabricated a series of low-cost Cu-based cathode materials.

[0003] Positive electrode oxides for sodium-ion batteries mainly include layered oxides and tunneled oxides. The tunneled oxides have a unique "S"-shaped channel in their crystalline structure, which gives them good rate characteristics and high stability against air and water. However, their initial charge / discharge specific capacity is low, resulting in a low practically usable specific capacity. Layered oxides have a periodic layered structure, are simple to fabricate, and have high specific capacity and voltage, making them the primary positive electrode material for sodium-ion batteries. To prevent sodium loss during the manufacturing process, excessive sodium salts are typically added during the material production process. After calcination, residual sodium salts remain, primarily in the form of sodium carbonate and sodium hydroxide, referred to as residual alkalinity. If the alkalinity of a sodium-ion battery positive electrode material is too high, the material will absorb moisture and become damp during processing. This increases viscosity during the slurry mixing process, forming a jelly-like substance, which can adversely affect processing characteristics.

[0004] In sodium-ion layered oxides, the transition metal layer is typically an MO6 octahedron formed by a transition metal element and six surrounding oxygen atoms, with sodium ions positioned between the transition metal layers, forming a layered structure in which MO6 polyhedron layers and NaO6 alkali metal layers are alternately arranged. This structure causes lattice distortion and phase transitions during the charge and discharge process of sodium-ion batteries, hindering the transport and diffusion of sodium ions, and most of the sodium ions are liberated to the surface of the material, where they undergo side reactions with the electrolyte, resulting in irreversible capacity loss, worsening cycle characteristics, and even causing a decrease in battery performance and even loss, posing a safety risk. Summary of the Invention [Problem to be solved by the invention]

[0005] The technical problem that the present invention aims to solve is as follows: The positive electrode material for sodium ion batteries according to the prior art has a high residual alkali content, and the presence of such residual alkali on the surface makes the material highly susceptible to moisture absorption and deterioration, resulting in poor compatibility with adhesives and reduced dispersibility and stability of the slurry, which is disadvantageous for the subsequent coating process.

[0006] In layered oxides, the transition metal layers are typically composed of MO6 octahedrons formed by a transition metal element and six surrounding oxygen atoms. Sodium ions are located between the transition metal layers, forming a layered structure in which MO6 polyhedron layers and NaO6 alkali metal layers are alternately arranged. These structures cause lattice distortion and phase transitions during the charge / discharge process of sodium-ion batteries, hindering the transport and diffusion of sodium ions. Most of the sodium ions are liberated to the surface of the material and undergo side reactions with the electrolyte, resulting in irreversible capacity loss, poor cycling performance, and even battery performance degradation and loss, posing safety risks. Previous techniques have mostly attempted to improve the structural stability of materials by doping with very small amounts of variable-valence metals, but the actual results have been unsatisfactory. After extensive research and development, the inventors have discovered that increasing the amount of doping element or synergistic doping of multiple elements is highly advantageous in stabilizing the crystalline structure of the material, reducing residual alkalinity on the surface of the positive electrode material, and reducing lattice distortion and phase transition effects during the charge / discharge process of sodium-ion batteries.

[0007] In view of the above technical problems, the object of the present invention is to provide a positive electrode material for a sodium ion battery and a manufacturing method thereof, which reduces the content of residual alkali on the surface of the positive electrode material for a sodium ion battery obtained by the manufacturing method, so that the capacity and rate of the sodium ion battery are at a relatively high level. [Means for solving the problem]

[0008] Specifically, the present invention provides the following technical solutions: In the first aspect, the present invention has a general formula: Na 1+a Ni 1-x-y-z Mn x Fe y A z O 2+i where -0.40 ≤ a ≤ 0.25, 0.08 < x < 0.5, 0.05 < y < 0.5, 0.0 < z < 0.26, -0.3 ≤ i ≤ 0.3, and A is selected from one or a combination of two or more of the elements Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu. A cathode material for a sodium-ion battery is provided. However, in the cathode material for the sodium-ion battery, there are two diffraction peaks at 42 - 46°.

[0009] Preferably, the general formula of the cathode material is Na 1+a Ni 1-x-y-z Mn x Fe y A z O2, where -0.40 ≤ a ≤ 0.20, 0.08 < x < 0.48, 0.05 < y < 0.5, 0.01 < z < 0.26, and A is selected from one or a combination of two or more of the elements Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu. However, in the cathode material for the sodium-ion battery, there are two diffraction peaks at 42 - 46°. More preferably, the general formula of the cathode material is Na 1+a Ni 1-x-y-z Mn x Fe y A z O2, where -0.40 ≤ a ≤ 0.20, 0.08 < x < 0.48, 0.05 < y < 0.45, 0.01 < z < 0.24, and A is selected from one or a combination of two or more of the elements Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu.

[0010] More preferably, the general formula of the cathode material is Na 1+aNi 1-x-y-z Mn x Fe y A z is O₂, where -0.40 ≦ a ≦ 0.20, 0.08 < x < 0.48, 0.05 < y < 0.5, 0.1 < z < 0.22, and A is selected from one or a combination of two or more of the elements Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu. However, in the positive electrode material for the sodium ion battery, there are two diffraction peaks at 42 to 46°.

[0011] Preferably, the general formula of the positive electrode material is Na 1+a Ni 1-x-y-z Mn x Fe y A z is O₂, where -0.30 ≦ a < 0.20, 0.15 < x < 0.35, 0.15 < y < 0.35, 0.1 < z < 0.22, and A is selected from one or a combination of two or more of the elements Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu. However, in the positive electrode material for the sodium ion battery, there are two diffraction peaks at 42 to 46° of the diffraction angle 2θ value.

[0012] Preferably, the A element contains a Zn element and an M element. However, the content of the Zn element is represented by b, and the total content of the Zn element and the M element is z. The general formula of the positive electrode material is Na 1+a Ni 1-x-y-z Mn x Fe y Zn b M z-bIt is O2, where -0.40 ≦ a ≦ 0.25, 0.08 < x < 0.5, 0.05 < y < 0.5, 0.0 < z < 0.26, 0 < b ≦ 0.1, M is selected from one or a combination of two or more of the elements Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B and Cu, and more preferably, in the above formula, -0.40 ≦ a ≦ 0.20, 0.08 < x < 0.48, 0.05 < y < 0.45, 0.01 < z < 0.24.

[0013] And / or, the A element contains Ti element and N element, provided that the content of Ti element is represented by c, and the total content of Ti element and N element is z. The general formula of the positive electrode material is Na 1+a ​​​​​​​​​​​​​​​​​​​​​​​​​​And / or, the A element contains Ti element, Zn element and X element. However, the content of Zn element is represented by b, the content of Ti element is represented by c, and the total content of Ti element, Zn element and X element is z. The general formula of the positive electrode material is Na 1+a Ni 1-x-y-z Mn x Fe y Zn b Ti c X z-b-c O2. In the formula, -0.40 ≦ a ≦ 0.25, 0.08 < x < 0.5, 0.05 < y < 0.5, 0.01 < z < 0.26, 0 < b ≦ 0.1, 0 < c < 0.24, and X is selected from one or a combination of two or more of Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B and Cu elements. Preferably, the general formula of the positive electrode material is Na 1+a Ni 1-x-y-z Mn x Fe y Zn b Ti c N z-b-c O2. In the formula, -0.40 ≦ a ≦ 0.25, 0.08 < x < 0.5, 0.05 < y < 0.5, 0.01 < z < 0.26, 0 < b ≦ 0.1, 0 < c ≦ 0.22, and X is selected from one or a combination of two or more of Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B and Cu elements. More preferably, the general formula of the positive electrode material is Na 1+a Ni 1-x-y-z Mn x Fe y Zn b Ti c N z-b-c O2. In the formula, -0.40 ≦ a ≦ 0.25, 0.08 < x < 0.5, 0.0 < y < 0.5, 0.01 < z < 0.26, 0 < b ≦ 0.1, 0 < c ≦ 0.17, and X is selected from one or a combination of two or more of Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B and Cu elements. Even more preferably, the positive electrode material contains at least one of Zn and Ti.

[0015] Preferably, the powder X-ray diffraction pattern of the sodium ion battery positive electrode material shows an α-NaFeO 2 type layered structure.

[0016] Preferably, in the powder X-ray diffraction pattern of the positive electrode material for a sodium ion battery, the full width at half maximum (FWHM) of two diffraction peaks having a diffraction angle 2θ value of 42 to 46° is 0.06 to 0.3°, and more preferably, the full width at half maximum (FWHM) is 0.06 to 0.25°.

[0017] And / or, the lattice spacing of the two diffraction peaks having a diffraction angle 2θ value of 42 to 46° is 1.5 to 3.0 Å, preferably, the lattice spacing of the two diffraction peaks having a diffraction angle 2θ value of 42 to 46° is 1.8 to 2.8 Å, and more preferably, the lattice spacing of the two diffraction peaks having a diffraction angle 2θ value of 42 to 46° is 1.8 to 2.3 Å.

[0018] Preferably, in the powder X-ray diffraction pattern of the sodium ion battery positive electrode material, the full width at half maximum (FWHM) of a diffraction peak having a diffraction angle 2θ value of about 43° is 0.08 to 0.18°, more preferably, the full width at half maximum (FWHM) of a diffraction peak having a diffraction angle 2θ value of about 43° is 0.15 to 0.18°, and / or the full width at half maximum (FWHM) of a diffraction peak at a diffraction angle 2θ value of about 45° is 0.09 to 0.22°; and / or the full width at half maximum (FWHM) of a diffraction peak at a diffraction angle 2θ value of about 43° is 0.08 to 0.14°, and the full width at half maximum (FWHM) of a diffraction peak at a diffraction angle 2θ value of about 45° is 0.09 to 0.20°; and / or the lattice spacing of a diffraction peak having a diffraction angle 2θ value of about 43° is 2.0 to 2.2 Å; and / or the lattice spacing of a diffraction peak having a diffraction angle 2θ value of about 45° is 2.0 to 2.1 Å; And / or, the ratio of the intensity of the diffraction peak at a diffraction angle 2θ value of around 43° to the intensity of the diffraction peak at a diffraction angle 2θ value of around 45° is 0.1 to 12.0, preferably 0.1 to 10.0, more preferably 0.5 to 6.6, and even more preferably 4 to 6.6.

[0019] Preferably, the powder X-ray diffraction pattern (XRD) of the positive electrode material for a sodium ion battery has three to five diffraction peaks at a diffraction angle 2θ value of 30 to 40°, Preferably, the full width at half maximum FWHM of three to five diffraction peaks having a diffraction angle 2θ value of 30 to 40° is 0.05 to 0.35°, and more preferably, the full width at half maximum FWHM is 0.08 to 0.3°; and / or the lattice spacing of three to five diffraction peaks having a diffraction angle 2θ value of 30 to 40° is 2.1 to 3 Å, preferably 2.4 to 2.8 Å; and / or there are three diffraction peaks at a diffraction angle 2θ value of 30 to 40°, and the diffraction angle 2θ values ​​are respectively around 33°, around 35°, and around 36°, and preferably the diffraction angle 2θ values ​​are respectively around 33.3°, around 35.3°, and around 36.6°; Alternatively, there are four diffraction peaks at a diffraction angle 2θ value of 30 to 40°, and the diffraction angle 2θ values ​​are respectively around 33°, around 35°, around 36°, and around 37°, and preferably the diffraction angle 2θ values ​​are respectively around 33.5°, around 35.1°, around 36.5°, and around 37.3°, Alternatively, there are five diffraction peaks at diffraction angle 2θ values ​​of 30 to 40°, and the diffraction angle 2θ values ​​are respectively around 32°, around 33°, around 34°, around 35°, and around 37°, and preferably the diffraction angle 2θ values ​​are respectively around 31.7°, around 33.4°, around 34.5°, around 35.2°, and around 36.6°.

[0020] More preferably, the full width at half maximum FWHM of a diffraction peak at a diffraction angle 2θ value of about 32° is 0.1 to 0.15°, the lattice spacing is 2.75 to 2.85 Å, and / or the full width at half maximum FWHM of a diffraction peak at a diffraction angle 2θ value of about 33° is 0.12 to 0.17°, the lattice spacing is 2.6 to 2.7 Å, and / or the full width at half maximum FWHM of a diffraction peak at a diffraction angle 2θ value of about 34° is 0.12 to 0.17°, the lattice spacing is 2.6 to 2.7 Å. M is 0.35 to 0.39°, the lattice spacing is 0.55 to 0.65 Å, and / or the full width at half maximum FWHM of a diffraction peak having a diffraction angle 2θ value of about 35° is 0.1 to 0.27°, the lattice spacing is 2.5 to 2.6 Å, and / or the full width at half maximum FWHM of a diffraction peak having a diffraction angle 2θ value of about 37° is 0.08 to 0.11°, and the lattice spacing is 2.4 to 2.5 Å.

[0021] Preferably, in a powder X-ray diffraction pattern (XRD) of the sodium ion battery positive electrode material, there is one diffraction peak at a diffraction angle 2θ value of around 16° and one diffraction peak at a diffraction angle 2θ value of around 41°, more preferably there is one diffraction peak at a diffraction angle 2θ value of around 16.5° and one diffraction peak at a diffraction angle 2θ value of around 41.5°, More preferably, the full width at half maximum (FWHM) of a diffraction peak having a diffraction angle 2θ value of about 16° is 0.11 to 0.16° and the lattice spacing is 5.3 to 5.4 Å, and / or the full width at half maximum (FWHM) of a diffraction peak having a diffraction angle 2θ value of about 41° is 0.1 to 0.23° and the lattice spacing is 2.1 to 2.2 Å.

[0022] Preferably, the mass percent content of the Mn element in the positive electrode material for a sodium ion battery is 3 to 28%, preferably, the mass percent content of the Mn element is 4 to 25%, more preferably, the mass percent content of the Mn element is 9 to 25%, and even more preferably, the mass percent content of the Mn element is 9 to 18%.

[0023] And / or the mass percent content of the Fe element is 3-28%, preferably the mass percent content of the Fe element is 4-25%, more preferably the mass percent content of the Fe element is 9-17%, even more preferably the mass percent content of the Fe element is 10.5-17%, or even more preferably the mass percent content of the Fe element is 9-14%.

[0024] And / or the mass percent content of the Ni element is 3 to 27%, preferably the mass percent content of the Ni element is 5 to 25%, more preferably the mass percent content of the Ni element is 12 to 25%, even more preferably the mass percent content of the Ni element is 14 to 19%, or even more preferably the mass percent content of the Ni element is 20 to 25%.

[0025] Preferably, the total content of residual alkali (free sodium) in the sodium ion battery positive electrode material is less than 3.5%, preferably 2.5 to 3.5%.

[0026] Preferably, the specific surface area of ​​the positive electrode material for a sodium ion battery is 0.2 to 1.3 m 2 / g, more preferably 0.3 to 1 m 2 / g.

[0027] And / or, the particle size D50 of the positive electrode material for a sodium ion battery is 2 to 18 μm, preferably 2 to 12 μm.

[0028] And / or, the tap density of the positive electrode material for a sodium ion battery is 1.0 to 2.9 g / cm 3and more preferably, the tap density of the positive electrode material for a sodium ion battery is 1.0 to 2.4 g / cm 3 is.

[0029] Preferably, the specific surface area of ​​the positive electrode material for a sodium ion battery is 0.5 to 1.3 m 2 / g, and / or the particle size D50 of the positive electrode material for a sodium ion battery is 2 to 6 μm, and / or the tap density of the positive electrode material for a sodium ion battery is 1.5 to 2 g / cm 3 is.

[0030] In a second aspect, the present invention provides a method for producing a positive electrode material for a sodium ion battery, comprising the steps of mixing a Na source, a Ni source, a Mn source, an Fe source, and an A source in a certain ratio, firing the mixture, cooling, and pulverizing the mixture to obtain a positive electrode material for a sodium ion battery.

[0031] Preferably, the mixing is carried out by a solid phase mixing method or a liquid phase mixing method.

[0032] Preferably, the firing is divided into two steps, in which in step 1 the raw material is pretreated at a temperature of 450 to 650°C and / or the pretreatment time is 3 to 10 hours, and in step 2 the pretreated raw material is treated at a temperature of 850 to 950°C and / or the treatment time is 8 to 40 hours.

[0033] Preferably, the temperature increase rate in the first step is 1 to 10° C. / min, and / or the temperature increase rate in the second step is 1 to 10° C. / min.

[0034] Preferably, the distance between the grinding discs is 0 to 2 mm, preferably the distance between the discs is 0 to 1.5 mm, and / or the rotation speed is 500 to 3000 rpm, preferably the rotation speed is 1000 to 2800 rpm.

[0035] Preferably, the calcination gas is selected from air, oxygen or a mixture thereof.

[0036] Preferably, the sodium source is one or more selected from sodium hydroxide, sodium carbonate, sodium nitrate, sodium oxalate, sodium chloride, sodium fluoride and sodium acetate.

[0037] Preferably, the A source is selected from oxides of one or more elements selected from the group consisting of Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B and Cu, or salts thereof, or organic compounds thereof; More preferably, the A source is selected from carbonates, oxalates, nitrates, and oxides of one or more elements selected from the group consisting of Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu; More preferably, the A source is one or more selected from zinc oxide, titanium dioxide, calcium oxide, copper oxide, aluminum oxide, yttrium oxide, diboron trioxide, barium oxide, niobium oxide, magnesium oxide, and zirconium oxide.

[0038] The sodium ion positive electrode material is produced by the method for producing a positive electrode material for a sodium ion battery.

[0039] In a third aspect, the present invention provides a positive electrode for a sodium ion battery, which uses the above-mentioned positive electrode material for a sodium ion battery as a positive electrode active material.

[0040] In a fourth aspect, the present invention provides a sodium-ion battery, the sodium-ion battery comprising: a positive electrode of the sodium-ion battery; a negative electrode; and a sodium salt-containing electrolyte.

[0041] Preferred is the use of said sodium ion battery as a power source in a photovoltaic power generation system, a power system, an energy storage system or a mobile storage device or a low-end electric vehicle.

[0042] Preferred is the use of said sodium ion battery in an energy storage device such as a distributed energy storage, a centralized energy storage or a low-end power battery.

[0043] In a fifth aspect, the present invention provides a power system, an energy storage system or a mobile storage device fabricated from the sodium-ion battery. [Effects of the Invention]

[0044] The beneficial effects obtained in the present invention are as follows. The positive electrode material for a sodium ion battery provided by the present invention is Na 1+a Ni 1-x-y-z Mn x Fe y A z The material has a chemical formula of O2, and the addition of modifier element A improves the structural stability of the material, forming a special XRD structure that provides stable channels for the transport of sodium ions, allowing the sodium ions to be sufficiently transported and diffused into the material, thereby reducing the content of free sodium ions on the surface of the material, i.e., the residual alkali content. This makes the material less susceptible to moisture absorption and degradation even in relatively humid environments, and prevents gelation during the battery slurry preparation process, improving the stability of the slurry. Because the sodium ion battery cathode material of the present invention has a relatively low residual alkali content, it is less likely to react with water and carbon dioxide in the air, and after production into a sodium ion battery, side reactions with the electrolyte are reduced, improving the battery stability.

[0045] The positive electrode material for sodium ion batteries of the present invention has the specific chemical formula and special XRD structure as described above. During the charge and discharge process of a sodium ion battery, sodium ions are frequently released, so the crystalline structure will not collapse or shrink, and the released sodium ions can return to the crystalline structure, ensuring that the sodium ion battery has a relatively high capacity. [Brief explanation of the drawings]

[0046] [Figure 1] FIG. 1 is an XRD pattern of the sodium ion cathode material of Example 1. [Figure 2] FIG. 2 is a charge / discharge curve diagram of the sodium ion positive electrode material of Example 1. [Figure 3] FIG. 3 is an XRD pattern of the sodium ion cathode material of Example 2. [Figure 4] FIG. 4 is a charge / discharge curve diagram of the sodium ion positive electrode material of Example 2. [Figure 5] FIG. 5 is an XRD pattern of the sodium ion cathode material of Example 3. [Figure 6] FIG. 6 is a charge / discharge curve diagram of the sodium ion positive electrode material of Example 3. [Figure 7] FIG. 7 is the XRD pattern of the sodium ion cathode material of Example 4. [Figure 8] FIG. 8 is a charge / discharge curve diagram of the sodium ion positive electrode material of Example 4. [Figure 9] FIG. 9 is the XRD pattern of the sodium ion cathode material of Example 5. [Figure 10] FIG. 10 is a charge / discharge curve diagram of the sodium ion positive electrode material of Example 5. [Figure 11] FIG. 11 is the XRD pattern of the sodium ion cathode material of Example 6. [Figure 12] FIG. 12 is a charge / discharge curve diagram of the sodium ion positive electrode material of Example 6. [Figure 13] FIG. 13 is an XRD pattern of the sodium ion positive electrode material of Comparative Example 1. [Figure 14] FIG. 14 is a charge / discharge curve diagram of the sodium ion positive electrode material of Comparative Example 1. [Figure 15] FIG. 15 is an XRD pattern of the sodium ion positive electrode material of Comparative Example 2. [Figure 16] FIG. 16 is a charge / discharge curve diagram of the sodium ion positive electrode material of Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0047] As mentioned above, an object of the present invention is to provide a sodium ion positive electrode material, a method for producing the same, and uses thereof.

[0048] In the prior art, there has been little research on reducing the residual alkali content (sodium carbonate) on the surface of a sodium-ion battery cathode material by controlling the structure of the sodium-ion cathode material. The sodium-ion battery cathode material of the present invention has a unique layered structure, and its X-ray diffraction pattern shows a second-strongest peak at a diffraction angle 2θ value of approximately 16° (a diffraction angle of approximately X° in the present invention indicates a diffraction angle of X°±1°, e.g., approximately 16° indicates 16°±1°, i.e., 15-17°), three to five diffraction peaks at a diffraction angle 2θ value of 30-40°, and at least two diffraction peaks at a diffraction angle 2θ value of 42-46°, with the diffraction angle 2θ values ​​of the two diffraction peaks being approximately 43° and 45°, respectively, and a first-strongest peak at a diffraction angle 2θ value of approximately 41.5°. On the one hand, these special diffraction peaks and full width at half maximum (FWHM) make the structure of the material more stable, ensuring that sodium ions are well-located inside the material and reducing the amount of free sodium ions on the surface of the material. The residual alkalinity (free sodium) of the material is relatively low, and when battery slurry is made from the material, it can be produced under conditions of humidity of less than 40%, and the slurry will not gel. On the other hand, these special diffraction peaks and full width at half maximum (FWHM) mean that the material has special lattice spacing and transport channels, providing sufficient channels for the transport and diffusion of sodium ions into the material, allowing the sodium ions to be smoothly released during the battery charge and discharge process, resulting in sodium-ion batteries with excellent capacity and rate characteristics.

[0049] The raw materials and equipment used in the following examples are provided as shown in Table 1. Unless otherwise specified, the raw materials used in the present invention are generally commercially available reagents of ordinary chemical purity. [Table 1]

[0050] The specific surface area of ​​the sodium ion cathode material in the present invention was measured in accordance with the Chinese National Standard GB / T19587-2006, "Measuring the Specific Surface Area of ​​Solid Materials by Gas Adsorption BET Method." The analytical equipment used was a Tristar II 3020 automatic specific surface area and pore size distribution analyzer. The measurement parameters were: 99.999% N2 as the adsorbent, liquid nitrogen as the coolant, P0 as the actual measurement, volumetric measurement mode, adsorption pressure deviation of 0.05 mmHg, equilibration time of 5 seconds, and relative pressure point selections of P / P0: 0.05, 0.1, 0.15, 0.2, 0.25, and 0.30. The sample was pretreated by weighing the mass of an empty sample tube plus stopper and recording it as M1. 3.8-4.2 g of sample was weighed and added to a 9.5 mm specific surface area measurement tube with a 3 / 8-inch valve. The FlowPrep Using a 060 degassing station, set to 200°C, purged with inert gas, heated for 30 minutes to degas, removed, cooled to room temperature, and weighed the mass of the sample tube + stopper + sample, recorded as M2. The mass of the sample is M = M2 - M1, loaded and measured, and the BET value recorded.

[0051] The tap density (TD) of the sodium ion cathode material in the present invention was measured in accordance with the Chinese National Standard GB / T5162-2006, Method for Measuring Metal Powder Tap Density. The measurement equipment was a ZS-202 tap density tester. The TD measurement parameters were: vibration frequency of 3000 rpm, vibration frequency of 250±10 rpm, amplitude of 3±0.1 mm, sample weighing accuracy of 50±0.5 g, tapping measuring cylinder size of 100 mL with an accuracy of 1 mL, and the maximum and minimum volumes were read and the arithmetic mean was calculated using the formula ρ=m / V. The result was rounded to two decimal places.

[0052] The particle size of the sodium ion cathode material in the examples of this invention was measured in accordance with the Chinese National Standard GB / T19077-2016 Particle Size Distribution - Laser Diffraction Method. Measurement equipment: Malvern Master Size 2000 laser particle size analyzer. Measurement steps: 1 g of powder was weighed and added to 60 mL of pure water, then ultrasonicated for 5 minutes. The sample was then injected into a sample injector for measurement and the measurement data was recorded. Measurement conditions: The measurement principle was Mie theory, the detection angle was 0-135°, the ultrasonic intensity was 40 kHz and 180 W, the particle refractive index was 1.692, the particle absorption coefficient was 1, the sample measurement time was 6 seconds, the number of background snaps was 6,000, and the light blocking level was 8-12%.

[0053] The residual alkalinity in the sodium ion positive electrode material of the present invention was measured as follows: 30 g ± 0.01 g of sample was accurately weighed and added to a 250 mL Erlenmeyer flask. A stirring bar was then added, followed by 100 mL of deionized water. The flask was then placed on a magnetic stirrer, and the flask was then turned on and stirred for 30 minutes. The mixed solution was then filtered using qualitative filter paper and a funnel. 1 mL of the filtrate was then taken and added to a 100 mL beaker, followed by a stirring bar. The beaker was then placed on a magnetic stirrer, and two drops of phenolphthalein indicator were added. The solution was then titrated with 0.05 mol / L hydrochloric acid standard solution until the color of the solution changed from red to colorless (V 初 = 0), the volume V1 of the 0.05 mol / L hydrochloric acid standard solution (end point 1, V1 = V 終1 -V 初 ) and record the volume of the 0.05 mol / L hydrochloric acid standard solution. Add two drops of methyl red indicator and the solution will change color from colorless to yellow. Titrate with 0.05 mol / L hydrochloric acid standard solution until the solution changes color from yellow to orange. Place the beaker in a heating oven and heat until the solution boils (the solution will change color from orange to yellow). Remove the beaker and allow it to cool to room temperature. Place the beaker on a magnetic stirrer again and titrate with 0.05 mol / L hydrochloric acid standard solution until the solution changes color from yellow to pale red. Record the volume V2 of the 0.05 mol / L hydrochloric acid standard solution (endpoint 2, V2 = V 終2 -V 終1) is recorded.

[0054] The formula for calculating the free sodium content is as follows: Na + (wt%) = (c(V1 + V2) × 10 -3 ×M×100) / m×100% Na2CO3(wt%) = (c × V2 × 10 -3 ×M1×100) / m×100% NaOH (wt%) = (c × (V1 - V2) × 10 -3 ×M2×100) / m×100% M is the relative atomic mass of sodium, M1 is the relative molar mass of sodium carbonate, M2 is the relative molar mass of sodium hydroxide, m is the mass of the sample in g, V1 is the first titration endpoint in mL, V2 is the second titration endpoint in mL, c is the concentration of the hydrochloric acid standard solution in mol / L, and the 100 in the numerator represents the dilution factor.

[0055] The XRD measurements of the sodium ion cathode materials of the examples of the present invention were performed using an X'Pert PRO MPD diffractometer. Measurement conditions: Cu tube, wavelength 1.54060 nm, Be window. In the incident light path, the Soller slit was 0.04 rad, the divergence slit was 1 / 2°, the light shield was 10 mm, and the anti-scatter slit was 1°. In the diffraction light path, the anti-scatter slit was 8.0 mm, the Soller slit was 0.04 rad, and a large Ni filter was used. The scanning range was 10 to 90°, the scanning step width was 0.013°, the measurement time per step was 30.6 seconds, the voltage was 40 kV, and the current was 40 mA. Powder sample preparation: Use a clean sampling spoon to place the powder in the groove of a glass slide (large particle samples need to be polished to a size less than 50 μm). Place one side of a scraper (greater than 20 mm) against the surface of the glass slide, slightly lift the other side (at an included angle of less than 10°), and scrape the surface of the powder sample with the edge of the scraper to flatten it. Rotate the glass slide 90° and scrape it again to flatten it. Scrap multiple times in both directions to ensure the sample surface is free of patterns. Remove excess powder around the glass slide, and then place it in the powder X-ray diffraction analyzer. Sample analysis: Open the measured sample file in High-Score Plus analysis software. First, determine the background, select peak search, identify the peaks, repeat the fitting, record the Williamson-Hall plot to calculate the grain size, select the corresponding phase, match the phase, modify the unit cell, and record the unit cell parameters. Measurement principle: The Bragg equation reflects the relationship between the diffraction line direction and crystal structure. For diffraction to occur, the Bragg equation: 2d sinθ=nλ (d: lattice spacing, θ: Bragg angle, λ: X-ray wavelength, n: reflection order) must be satisfied. When X-rays are irradiated onto a sample, the scattered X-rays from each atom in the crystal interfere with each other, producing a strong X-ray diffraction line in a specific direction. When X-rays are irradiated onto a sample from different angles, diffraction occurs at different crystal planes, and the detector recognizes the number of diffracted photons reflected from the crystal planes in question, obtaining a pattern of the relationship between angle and intensity.

[0056] The element content of the sodium ion cathode material in this example was measured using an inductively coupled plasma (ICP) method. Detection equipment: ICP-OES iCAP 6300 inductively coupled plasma optical emission spectrometer. Detection conditions: the detector had more than 290,000 detection units, the camera temperature of the detector cooling system was below -35°C, the optical chamber temperature of the optical system was 38±0.1°C, the optical system wavelength range was 166-847 nm, the plasma observation mode was vertical observation, the plasma observation height was 14 mm, the RF power was 1150 W, the frequency was 27.12 MHz, the auxiliary gas flow rate of the sampling system was 0.5 L / min, the nebulizing gas flow rate of the sampling system was 0.6 L / min, and the pump speed was 50 rpm. Trace measurement steps: Accurately weigh 0.2000-0.2100 g of sample and place it in a 50 mL quartz beaker. Add 10 mL of 1:1 aqua regia and place on a watch glass in a heating oven to completely dissolve. Transfer to a 50 mL measuring flask, adjust to volume, shake evenly, load, measure, and record the data. Main measurement: Take 1 mL of the solution that has been shaken evenly and place it in a 100 mL measuring flask, adjust to volume to 100 mL, shake evenly, load, measure, and record the data.

[0057] The sodium ion battery of the present invention is composed of electrodes, an electrolyte, a separator, and an aluminum laminate film. Specifically, the electrodes include a positive electrode and a negative electrode. The positive electrode is made of materials such as a positive electrode current collector, a positive electrode active material coated on the positive electrode current collector, an adhesive, and a conductive additive, and the positive electrode active material is the positive electrode material of the present invention. The negative electrode is made of materials such as a current collector, a negative electrode active material coated on the current collector, an adhesive, and a conductive additive. The separator is a PP / PE film commonly used in the art to separate the positive electrode and the negative electrode from each other. The aluminum laminate film is a covering material for the positive electrode, negative electrode, separator, and electrolyte.

[0058] The adhesive of the present invention is primarily used to improve the adhesion between positive electrode active material particles and between positive electrode active material particles and a current collector. The adhesive of the present invention may be a commercially available adhesive commonly used in the art. Specifically, the adhesive may be selected from polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, poly(vinylidene fluoride), polyethylene, polypropylene, styrene-butadiene rubber, acrylated (esterified) styrene-butadiene rubber, epoxy resin, nylon, or a combination thereof.

[0059] The conductive additive of the present invention may be a commercially available conductive additive commonly used in the art. Specifically, the conductive additive may be selected from carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, or carbon fiber), metal-based materials (e.g., metal powder or metal fiber of copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives), or combinations thereof.

[0060] In the following examples, the specific operating method for fabricating a sodium ion button battery using the cathode material prepared in the present invention is as follows: Preparation of positive electrode: The positive electrode material of the present invention, adhesive polyvinylidene fluoride (PVDF), and conductive carbon black (SP) are thoroughly mixed in a weight ratio of 7:2:1, stirred to form a uniform slurry, coated on an aluminum foil current collector, dried, and pressed to obtain a plate. After pressing, the positive plate is pressed, weighed, and baked. The battery is then assembled in a vacuum glove box. The button battery base is placed on top of the base, followed by nickel foam (2.5 mm) and a negative electrode metallic sodium sheet (manufacturer: Shenzhen Youken Technology Co., Ltd.). 0.5 g of electrolyte is injected in an environment with a relative humidity of less than 1.5%. The electrolyte is a mixed solvent of ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) in a mass ratio of 1:1:1. The electrolyte is a 1 mol / L lithium hexafluorophosphate solution. A separator and a positive plate are then placed, and the button battery cover is then placed and sealed. The button battery model number is CR2430.

[0061] In the present invention, the unit of the half width of the diffraction peak is the same as the unit of the diffraction angle 2θ. The present invention will be described in more detail below using specific examples with reference to the drawings.

[0062] Example 1 Sodium carbonate, manganese carbonate, nickel carbonate, ferric oxide, zinc oxide, calcium oxide, and copper oxide were weighed out in amounts corresponding to the stoichiometric molar ratio of Na:Mn:Ni:Fe:Zn:Ca:Cu = 0.82:0.32:0.26:0.29:0.08:0.03:0.02, and then added to an ultra-high-speed multi-function mixer at 4000 rpm and mixed for 30 minutes. The uniformly mixed materials were then heated from room temperature to 550°C at a rate of 3°C / min in an air atmosphere, held at this temperature for 4 hours, then heated to 950°C at a rate of 5°C / min and held at this temperature for 12 hours, then naturally cooled, crushed at a disk distance of 1.0 mm and a speed of 1800 rpm, and sieved to obtain a powder with the molecular formula Na. 0.82 N i0.26 Mn 0.32 Zn 0.08 Fe 0.29 Ca 0.03 Cu 0.02We obtain O2, a positive electrode material for sodium-ion batteries.

[0063] FIG. 1 shows the XRD pattern of the positive electrode material for a sodium-ion battery of this example. As can be seen from the figure, the diffraction angle 2θ value of 16.48° is the second strongest peak, the full width at half maximum (FWHM) is 0.13°, and the lattice spacing is 5.374 Å. There are five diffraction peaks at diffraction angles 2θ between 30 and 40°. The diffraction peak at 2θ of 31.71° has a full width at half maximum (FWHM) of 0.13° and a lattice plane spacing of 2.820 Å, the diffraction peak at 2θ of 33.39° has a full width at half maximum (FWHM) of 0.163° and a lattice plane spacing of 2.681 Å, the diffraction peak at 2θ of 34.49° has a full width at half maximum (FWHM) of 0.37° and a lattice plane spacing of 2.598 Å, the diffraction peak at 2θ of 35.20° has a full width at half maximum (FWHM) of 0.13° and a lattice plane spacing of 2.548 Å, and the diffraction peak at 2θ of 36.54° has a full width at half maximum (FWHM) of 0.114° and a lattice plane spacing of 2.457 Å. The strongest peak is at a diffraction angle 2θ of 41.56°, with a full width at half maximum (FWHM) of 0.104° and a lattice spacing of 2.171 Å. Two diffraction peaks are present between 2θ of 42 and 46°. The diffraction peak at 2θ of 42.72° has a full width at half maximum (FWHM) of 0.18° and a lattice spacing of 2.115 Å, while the diffraction peak at 2θ of 45.01° has a full width at half maximum (FWHM) of 0.13° and a lattice spacing of 2.013 Å. The peak intensity of the diffraction peak at 2θ of around 43° is 0.87 times that of the diffraction peak at 2θ of around 45°.

[0064] The positive electrode material was measured to have a residual alkali content of 2.32% and a specific surface area of ​​0.9m 2 / g, particle size D50 is 8.5 μm, and tap density TD is 1.65 g / cm 3 In addition, a button battery was manufactured using the positive electrode material of this example, and the capacity was measured. Figure 2 shows the 0.1C / 0.1C charge / discharge curve of the positive electrode material of this example under the condition of 4.0 to 2.0V.

[0065] Example 2 Sodium carbonate, manganese carbonate, nickel oxide, ferrous oxalate, zinc oxide, titanium dioxide, and yttrium oxide were weighed out in amounts corresponding to the stoichiometric molar ratio of Na:Mn:Ni:Fe:Zn:Ti:Y=0.78:0.32:0.27:0.297:0.083:0.02:0.01, and then added to an ultra-high-speed multi-function mixer at a rotation speed of 10,000 rpm for 15 minutes to achieve uniform mixing. The uniformly mixed materials were then heated to 500°C at a rate of 5°C / min in an air atmosphere, held at this temperature for 3 hours, then heated to 945°C at a rate of 3°C / min, held at this temperature for 16 hours, and then naturally cooled. The mixture was then pulverized at a disk distance of 1.5 mm at a rotation speed of 2,000 rpm and sieved to obtain a powder with the molecular formula Na. 0.78 Ni 0.27 Mn 0.32 Zn 0.083 Fe 0.297 Ti 0.02 Y 0.01 We obtain O2, a positive electrode material for sodium-ion batteries.

[0066] 3 shows the XRD pattern of the positive electrode material for a sodium-ion battery of this example. As can be seen from the figure, the diffraction angle 2θ of 16.55° is the second strongest peak, with a FWHM of 0.117° and a lattice plane spacing of 5.352 Å. There are four diffraction peaks at diffraction angles 2θ of 30 to 40°. The diffraction peak at 2θ of 33.51° has a FWHM of 0.12° and a lattice plane spacing of 2.672 Å. The diffraction peak at 2θ of 35.14° has a FWHM of 0.101° and a lattice plane spacing of 2.552 Å. The diffraction peak at 2θ of 36.50° has a FWHM of 0.102° and a lattice plane spacing of 2.460 Å. The diffraction peak at 2θ of 37.37° has a FWHM of 0.110° and a lattice plane spacing of 2.404 Å. The strongest peak is at a diffraction angle 2θ of 41.55°, with a full width at half maximum (FWHM) of 0.1° and a lattice spacing of 2.172 Å. Two diffraction peaks are present between diffraction angle 2θ of 42 and 46°. The diffraction peak at 2θ of 42.77° has a full width at half maximum (FWHM) of 0.17° and a lattice spacing of 2.112 Å, while the diffraction peak at 2θ of 45.03° has a full width at half maximum (FWHM) of 0.09° and a lattice spacing of 2.012 Å. The peak intensity of the diffraction peak at 2θ of around 43° is 1.38 times that of the diffraction peak at 2θ of around 45°.

[0067] The residual alkali content of the positive electrode material was measured to be 2.08%, and the specific surface area (BET) was 0.77 m 2 / g, particle size D50 is 11.0 μm, and tap density TD is 2.2 g / cm 3 In addition, a button battery was manufactured using the positive electrode material of this example, and the capacity was measured. Figure 4 shows a 0.1C / 0.1C charge / discharge curve of the positive electrode material of this example under conditions of 4.0 to 2.0V.

[0068] Example 3 Sodium carbonate, manganese oxide, nickel oxide, ferric oxide, zinc oxide, and titanium dioxide were weighed out in amounts corresponding to the stoichiometric molar ratio of Na:Mn:Ni:Fe:Zn:Ti=0.81:0.32:0.24:0.286:0.098:0.056, and then added to an ultra-high-speed multi-function mixer at a rotation speed of 14,000 rpm for 25 minutes to achieve uniform mixing. The uniformly mixed materials were then heated to 540°C at a rate of 6°C / min in an air atmosphere, held at this temperature for 7 hours, then heated to 974°C at a rate of 4°C / min, held at this temperature for 10 hours, and then cooled naturally. The mixture was then pulverized at a disk distance of 0.6 mm and a rotation speed of 2,000 rpm, and sieved to obtain a powder with the molecular formula Na. 0.81 Ni 0.24 Mn 0.32 Ti 0.056 Zn 0.098 Fe 0.286 The cathode material is O2.

[0069] Figure 5 shows the XRD pattern of the positive electrode material of this example. As can be seen from the figure, the diffraction angle 2θ value of 16.4° is the second strongest peak, the full width at half maximum FWHM is 0.122°, and the lattice plane spacing is 5.378Å. There are three diffraction peaks at diffraction angle 2θ values ​​of 30 to 40°. The diffraction peak at 2θ = 33.3° has a full width at half maximum FWHM of 0.131° and a lattice plane spacing of 2.685Å. The diffraction peak at 2θ = 35.3° has a full width at half maximum FWHM of 0.258° and a lattice plane spacing of 2.541Å. The diffraction peak at 2θ = 36.6° has a full width at half maximum FWHM of 0.233° and a lattice plane spacing of 2.452Å. The diffraction angle 2θ value of 41.5° is the first strongest peak, the full width at half maximum FWHM is 0.222° and a lattice plane spacing of 2.169Å. There are two diffraction peaks at diffraction angles 2θ between 42 and 46°, with the diffraction peak at 2θ of 42.9° having a full width at half maximum (FWHM) of 0.088° and a lattice spacing of 2.103 Å, and the diffraction peak at 2θ of 45.0° having a full width at half maximum (FWHM) of 0.218° and a lattice spacing of 2.009 Å. The peak intensity of the diffraction peak at 2θ around 43° is 0.84 times that of the diffraction peak at 2θ around 45°.

[0070] The residual alkali content of the positive electrode material was measured to be 2.98%, and the specific surface area (BET) was 0.64 m 2 / g, particle size D50 is 4.6 μm, and tap density TD is 1.5 g / cm 3 In addition, a button battery was manufactured using the positive electrode material of this example, and the capacity was measured. Figure 6 shows a 0.1C / 0.1C charge / discharge curve of the positive electrode material of this example under the condition of 4.0 to 2.0V.

[0071] Example 4 Sodium nitrate, manganese trioxide, nickel oxalate, ferrous oxalate, titanium dioxide, and aluminum oxide were weighed out in amounts corresponding to the stoichiometric molar ratio of Na:Mn:Ni:Fe:Ti:Al = 0.78:0.22:0.41:0.19:0.17:0.01, and then added to an ultra-high-speed multi-function mixer at a rotation speed of 17,000 rpm for 45 minutes until uniformly mixed. The uniformly mixed materials were heated to 580°C at a rate of 2°C / min in an air and oxygen atmosphere, held at this temperature for 6 hours, then heated to 890°C at a rate of 5°C / min, held at this temperature for 18 hours, and then cooled naturally. The mixture was then crushed and sieved at a disk distance of 0.8 mm at a rotation speed of 1,800 rpm to obtain a powder with the molecular formula Na. 0.78 Ni 0.41 Fe 0.19 Mn 0.22 Ti 0.17 Al 0.01 The cathode material is O2.

[0072] 7 shows the XRD pattern of the positive electrode material of this example. As can be seen from the figure, the diffraction angle 2θ value of 16.39° is the second strongest peak, with a full width at half maximum (FWHM) of 0.130° and a lattice plane spacing of 5.403 Å. There are four diffraction peaks at diffraction angles 2θ of 30 to 40°. The full width at half maximum (FWHM) of the diffraction peak at 2θ = 33.18° is 0.151° and a lattice plane spacing of 2.698 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ = 35.21° is 0.125° and a lattice plane spacing of 2.547 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ = 36.53° is 0.125° and a lattice plane spacing of 2.458 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ = 37.20° is 0.087° and a lattice plane spacing of 2.415 Å. The strongest peak is at a diffraction angle 2θ of 41.48°, with a full width at half maximum (FWHM) of 0.098° and a lattice spacing of 2.175 Å. Two diffraction peaks are present between 2θ of 42 and 46°. The diffraction peak at 2θ of 43.22° has a full width at half maximum (FWHM) of 0.081° and a lattice spacing of 2.092 Å, while the diffraction peak at 2θ of 44.91° has a full width at half maximum (FWHM) of 0.09° and a lattice spacing of 2.017 Å. The peak intensity of the diffraction peak at 2θ around 43° is 6.56 times that of the diffraction peak at 2θ around 45°.

[0073] The positive electrode material was measured to have a residual alkali content of 3.35% and a specific surface area of ​​0.55m 2 / g, particle size D50 is 5.5 μm, and tap density TD is 1.85 g / cm 3 In addition, a button battery was manufactured using the positive electrode material of this example, and the capacity was measured. Figure 8 shows a 0.1C / 0.1C charge / discharge curve of the positive electrode material of this example under conditions of 4.0 to 2.0V.

[0074] Example 5 Sodium carbonate, manganese oxalate, nickel oxalate, ferrous oxalate, titanium oxide, and boron trioxide were weighed out in amounts corresponding to the stoichiometric molar ratio of Na:Mn:Ni:Fe:Ti:B=0.88:0.204:0.454:0.2:0.137:0.005, and then added to an ultra-high-speed multi-function mixer at a rotation speed of 20,000 rpm for 60 minutes to achieve uniform mixing. The uniformly mixed materials were then heated to 600°C at a rate of 6°C / min in an air and oxygen atmosphere, held at this temperature for 3 hours, then heated to 850°C at a rate of 8°C / min, held at this temperature for 36 hours, and then naturally cooled. The mixture was then crushed at a disk distance of 0.4 mm at a rotation speed of 2200 rpm and sieved to obtain a powder with the molecular formula Na. 0.88 Ni 0.454 Mn 0.204 Ti 0.137 Fe 0.2 B 0.005 The cathode material is O2.

[0075] 9 shows the XRD pattern of the positive electrode material of this example. As can be seen from the figure, the diffraction angle 2θ value of 16.53° is the second strongest peak, with a full width at half maximum (FWHM) of 0.126° and a lattice plane spacing of 5.359 Å. There are four diffraction peaks at diffraction angles 2θ of 30 to 40°. The full width at half maximum (FWHM) of the diffraction peak at 2θ = 33.46° is 0.121° and a lattice plane spacing of 2.676 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ = 35.07° is 0.121° and a lattice plane spacing of 2.557 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ = 36.42° is 0.127° and a lattice plane spacing of 2.465 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ = 37.20° is 0.110° and a lattice plane spacing of 2.415 Å. The strongest peak is at a diffraction angle 2θ of 41.46°, with a full width at half maximum (FWHM) of 0.118° and a lattice spacing of 2.176 Å. Two diffraction peaks are present between diffraction angle 2θ of 42 and 46°. The diffraction peak at 2θ of 43.23° has a full width at half maximum (FWHM) of 0.107° and a lattice spacing of 2.091 Å, while the diffraction peak at 2θ of 44.93° has a full width at half maximum (FWHM) of 0.14° and a lattice spacing of 2.016 Å. The peak intensity of the diffraction peak at 2θ around 43° is 4.14 times that of the diffraction peak at 2θ around 45°.

[0076] The residual alkali content of the positive electrode material was measured to be 3.47%, and the specific surface area (BET) was 0.99 m 2 / g, particle size D50 is 3.6 μm, and tap density TD is 1.6 g / cm 3 In addition, a button battery was manufactured using the positive electrode material of this example, and the capacity was measured. Fig. 10 is a 0.1C / 0.1C charge / discharge curve diagram of the positive electrode material of this example under the condition of 4.0 to 2.0V.

[0077] Example 6 Sodium carbonate, manganese oxalate, nickel oxalate, ferrous oxalate, titanium dioxide, and zinc oxide were weighed out in amounts corresponding to the stoichiometric molar ratio of Na:Mn:Ni:Fe:Ti:Zn=0.8:0.21:0.38:0.2:0.14:0.07, and then added to an ultra-high-speed multi-function mixer at a rotation speed of 25,000 rpm for 30 minutes to achieve uniform mixing. The uniformly mixed materials were heated to 520°C at a rate of 4°C / min in an air and oxygen atmosphere, held at this temperature for 5 hours, then heated to 910°C at a rate of 7°C / min and held at this temperature for 40 hours, then naturally cooled, crushed at a disk distance of 0.4 mm at a rotation speed of 2,200 rpm, and sieved to obtain a powder with the molecular formula Na. 0.8 Ni 0.38 Mn 0.21 Ti 0.14 Fe 0.2 Zn 0.07 O 1.85 A positive electrode material is obtained.

[0078] 11 shows the XRD pattern of the positive electrode material of this example. As can be seen from the figure, the diffraction angle 2θ value of 16.48° is the second strongest peak, with a full width at half maximum (FWHM) of 0.157° and a lattice plane spacing of 5.374 Å. There are four diffraction peaks at diffraction angles 2θ of 30 to 40°. The full width at half maximum (FWHM) of the diffraction peak at 2θ = 33.37° is 0.164° and a lattice plane spacing of 2.683 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ = 35.16° is 0.175° and a lattice plane spacing of 2.550 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ = 36.50° is 0.158° and a lattice plane spacing of 2.460 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ = 37.23° is 0.110° and a lattice plane spacing of 2.413 Å. The strongest peak is at a diffraction angle 2θ of 41.50°, with a full width at half maximum (FWHM) of 0.139° and a lattice spacing of 2.174 Å. Two diffraction peaks are present at diffraction angle 2θ values ​​of 42 to 46°. The diffraction peak at 2θ of 43.25° has a full width at half maximum (FWHM) of 0.102° and a lattice spacing of 2.09 Å, while the diffraction peak at 2θ of 44.96° has a full width at half maximum (FWHM) of 0.12° and a lattice spacing of 2.015 Å. The peak intensity of the diffraction peak at 2θ around 43° is 6.01 times that of the diffraction peak at 2θ around 45°.

[0079] The positive electrode material was measured to have a residual alkali content of 2.71% and a specific surface area of ​​0.90 m 2 / g, particle size D50 is 3.5 μm, and tap density TD is 1.72 g / cm 3 In addition, a button battery was manufactured using the positive electrode material of this example, and the capacity was measured. Fig. 12 is a 0.1C / 0.1C charge / discharge curve diagram of the positive electrode material of this example under the condition of 4.0 to 2.0V.

[0080] (Comparative Example 1) Sodium nitrate, manganese trioxide, nickel oxalate, ferrous oxalate, copper oxide, and zinc oxide were weighed out in amounts corresponding to the stoichiometric molar ratio of Na:Mn:Ni:Fe:Cu:Zn=0.87:0.32:0.23:0.29:0.15:0.01, and then added to an ultra-high-speed multi-function mixer at a rotation speed of 17,000 rpm for 45 minutes until uniformly mixed. The uniformly mixed materials were heated to 850°C at a rate of 5°C / min in an air and oxygen atmosphere, held at constant temperature for 20 hours, then naturally cooled, and crushed at a disk distance of 0.9 mm and a rotation speed of 1,800 rpm. The mixture was then sieved to obtain a powder with the molecular formula Na. 0.87 Ni 0.23 Fe 0.29 Mn 0.32 Cu 0.15 Zn 0.01 The cathode material is O2.

[0081] 13 shows the XRD pattern of the positive electrode material of this example. As can be seen from the figure, the diffraction angle 2θ value of 16.52° is the second strongest peak, with a full width at half maximum (FWHM) of 0.120° and a lattice plane spacing of 5.3613 Å. There are four diffraction peaks at diffraction angles 2θ of 30 to 40°. The full width at half maximum (FWHM) of the diffraction peak at 2θ = 33.44° is 0.149° and a lattice plane spacing of 2.677 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ = 35.22° is 0.124° and a lattice plane spacing of 2.546 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ = 36.56° is 0.115° and a lattice plane spacing of 2.455 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ = 38.67° is 0.18° and a lattice plane spacing of 2.326 Å. The strongest peak is at a diffraction angle 2θ of 41.58°, with a full width at half maximum (FWHM) of 0.089° and a lattice spacing of 2.169 Å. One diffraction peak is present at diffraction angle 2θ of 42 to 46°, with the diffraction peak at 2θ of 45.055° having a full width at half maximum (FWHM) of 0.07° and a lattice spacing of 2.01 Å.

[0082] The residual alkali content of the positive electrode material was 4.19%, and the BET specific surface area was 0.64 m 2 / g, particle size D50 is 7.1 μm, and tap density TD is 1.98 g / cm 3 In addition, a button battery was manufactured using the positive electrode material of this example, and the capacity was measured. Fig. 14 is a 0.1C / 0.1C charge / discharge curve diagram of the positive electrode material of this example under the condition of 4.0 to 2.0V.

[0083] (Comparative Example 2) Sodium carbonate, manganese carbonate, nickel carbonate, ferric oxide, titanium dioxide, and diboron trioxide were weighed out in amounts corresponding to the stoichiometric molar ratio of Na:Mn:Ni:Fe:Ti:B=0.86:0.15:0.33:0.28:0.23:0.01, and then added to an ultra-high-speed multi-function mixer at a rotation speed of 25,000 rpm for 30 minutes until uniformly mixed. The uniformly mixed materials were heated to 520°C at a rate of 4°C / min in an air and oxygen atmosphere, held at this temperature for 5 hours, then heated to 830°C at a rate of 7°C / min, held at this temperature for 6 hours, then naturally cooled, crushed at a disk distance of 0.9 mm, at a rotation speed of 1,800 rpm, and sieved to obtain a powder with the molecular formula Na. 0.86 Ni 0.33 Mn 0.15 Ti 0.23 Fe 0.28 B 0.01 The cathode material is O2.

[0084] FIG. 15 shows the XRD pattern of the positive electrode material of this example. As can be seen from the figure, the diffraction angle 2θ value of 16.54° is the second strongest peak, the full width at half maximum (FWHM) is 0.148°, and the lattice spacing is 5.353 Å. There are five diffraction peaks at diffraction angles 2θ between 30 and 40°. The diffraction peak at 2θ of 32.3° has a full width at half maximum (FWHM) of 0.160° and a lattice plane spacing of 2.767 Å, ​​the diffraction peak at 2θ of 33.47° has a full width at half maximum (FWHM) of 0.156° and a lattice plane spacing of 2.674 Å, the diffraction peak at 2θ of 34.95° has a full width at half maximum (FWHM) of 0.22° and a lattice plane spacing of 2.565 Å, the diffraction peak at 2θ of 36.29° has a full width at half maximum (FWHM) of 0.213° and a lattice plane spacing of 2.473 Å, and the diffraction peak at 2θ of 37.18° has a full width at half maximum (FWHM) of 0.13° and a lattice plane spacing of 2.416 Å. The strongest peak is at a diffraction angle 2θ of 41.36°, with a full width at half maximum (FWHM) of 0.207° and a lattice spacing of 2.183 Å. Two diffraction peaks are present at diffraction angle 2θ values ​​of 42 to 46°. The diffraction peak at 2θ of 43.2° has a full width at half maximum (FWHM) of 0.12° and a lattice spacing of 2.093 Å, while the diffraction peak at 2θ of 44.81° has a full width at half maximum (FWHM) of 0.40° and a lattice spacing of 2.021 Å. The peak intensity of the diffraction peak at 2θ around 43° is 6.91 times that of the diffraction peak at 2θ around 45°.

[0085] The positive electrode material was measured to have a residual alkali content of 4.07% and a specific surface area of ​​0.45m 2 / g, particle size D50 is 7.0 μm, and tap density TD is 1.89 g / cm 3 In addition, a button battery was manufactured using the positive electrode material of this example, and the capacity was measured. Fig. 16 is a 0.1C / 0.1C charge / discharge curve diagram of the positive electrode material of this example under the condition of 4.0 to 2.0V. [Table 2]

[0086] As can be seen from Table 2, the positive electrode material for sodium ion batteries provided by the present invention is 1+a Ni 1-x-y-z Mn x Fe y A z With the chemical formula of O2, the structural stability of the material is improved by adding the modifying elements Zn or Ti and other A elements, resulting in an XRD diffraction peak of an O3 layered structure material, with two special diffraction peaks at a diffraction angle 2θ value of 42-46°. These special diffraction peaks provide stable channels for the transport of sodium ions, allowing them to be sufficiently transported and diffused into the material, reducing the amount of free sodium ions on the surface of the material and keeping the residual alkali content below 3.5%. The material is resistant to moisture absorption and degradation even in relatively humid environments, and gelation does not occur during the battery slurry production process, improving the stability of the slurry.

[0087] The positive electrode material for sodium ion batteries of the present invention has the specific chemical formula and special XRD structure. During the charge and discharge process of a sodium ion battery, sodium ions are frequently released, so the crystalline structure does not shrink and the released sodium ions can return to the crystalline structure. In addition, the positive electrode material has a relatively low residual alkali content, so that after being manufactured into a sodium ion battery, side reactions with the electrolyte are reduced, and it is ensured that the sodium ion battery has a relatively high capacity and good rate characteristics.

[0088] The applicant asserts that the above is merely a form for implementing the present invention, and that the scope of the claims of the present invention is not limited thereto. It should be obvious to a person skilled in the art that any modifications or substitutions that a person skilled in the art can easily think of within the technical scope disclosed in the present invention fall within the scope of the claims and disclosure of the present invention.

[0089] (Addendum) (Appendix 1) A positive electrode material for a sodium ion battery, comprising: The general formula of the positive electrode material is Na 1+a Ni 1-x-y-z Mnx Fe y A z O 2+i where -0.40 ≦ a ≦ 0.25, 0.08 < x < 0.5, 0.05 < y < 0.5, 0.0 < z < 0.26, -0.3 ≦ i ≦ 0.3, and A is selected from one or a combination of two or more of the elements Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu. However, in the positive electrode material for the sodium-ion battery, there are at least two diffraction peaks at a diffraction angle 2θ value of 42 to 46°, and the diffraction angle 2θ values of the two diffraction peaks are around 43° and around 45°, respectively. A positive electrode material for a sodium-ion battery characterized by this.

[0090] (Appendix 2) The general formula of the positive electrode material is Na 1+a Ni 1-x-y-z Mn x Fe y A z O2, where -0.40 ≦ a ≦ 0.20, 0.08 < x < 0.48, 0.05 < y < 0.45, 0.01 < z < 0.24, and A is selected from one or a combination of two or more of the elements Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu. The positive electrode material for a sodium-ion battery according to Appendix 1, characterized by this.

[0091] (Appendix 3) The A element contains a Zn element and an M element. However, the content of the Zn element is represented by b, and the total content of the Zn element and the M element is z. The general formula of the positive electrode material is Na 1+a Ni 1-x-y-z Mn x Fe y Zn b M z-bO₂, where -0.40 ≤ a ≤ 0.25, 0.08 < x < 0.5, 0.05 < y < 0.5, 0.0 < z < 0.26, 0 < b ≤ 0.10, M is selected from one or more combinations of the elements Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu, preferably, where -0.40 ≤ a ≤ 0.20, 0.08 < x < 0.48, 0.05 < y < 0.45, 0.01 < z < 0.24. And / or, the A element contains Ti element and N element, provided that the content of Ti element is represented by c, and the total content of Ti element and N element is z. The general formula of the positive electrode material is Na 1+a Ni 1-x-y-z Mn x Fe y Ti c N z-c O₂, where -0.40 ≤ a ≤ 0.25, 0.08 < x < 0.5, 0.05 < y < 0.5, 0.0 < z < 0.26, 0 < c < 0.24, N is selected from one or more combinations of the elements Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu, preferably, where -0.40 ≤ a ≤ 0.20, 0.08 < x < 0.48, 0.05 < y < 0.45, 0.01 < z < 0.24. And / or, the A element contains Ti element, Zn element and X element, provided that the content of Zn element is represented by b, the content of Ti element is represented by c, and the total content of Ti element, Zn element and X element is z. The general formula of the positive electrode material is Na 1+a Ni 1-x-y-z Mn x Fe y Zn b Ti c X z-b-cO2, where -0.40 ≦ a ≦ 0.25, 0.08 < x < 0.5, 0.05 < y < 0.5, 0.0 < z < 0.26, 0 < b ≦ 0.1, 0 ≦ c < 0.24, and X is selected from one or more combinations of Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu elements. Preferably, in the formula, -0.40 ≦ a ≦ 0.20, 0.08 < x < 0.48, 0.05 < y < 0.45, 0.01 < z < 0.24. Preferably, provided that the powder X-ray diffraction pattern of the positive electrode material for the sodium ion battery shows an α-NaFeO2 type layered structure, the positive electrode material for the sodium ion battery according to Appendix 1.

[0092] (Appendix 4) In the powder X-ray diffraction pattern of the positive electrode material for the sodium ion battery, the full width at half maximum FWHM of two diffraction peaks with diffraction angle 2θ values of 42 - 46° is 0.06 - 0.3°, preferably, the full width at half maximum FWHM is 0.06 - 0.25°. And / or, the lattice plane spacing of two diffraction peaks with diffraction angle 2θ values of 42 - 46° is 1.5 - 3.0 Å, preferably, the lattice plane spacing of two diffraction peaks with diffraction angle 2θ values of 42 - 46° is 1.8 - 2.8 Å, more preferably, the lattice plane spacing of two diffraction peaks with diffraction angle 2θ values of 42 - 46° is 1.8 - 2.3 Å. The positive electrode material for the sodium ion battery according to any one of Appendices 1 - 3.

[0093] (Appendix 5) In the powder X-ray diffraction pattern of the positive electrode material for the sodium ion battery, the full width at half maximum FWHM of the diffraction peak has one or more of the following characteristics. (1) The full width at half maximum FWHM of the diffraction peak with a diffraction angle 2θ value near 43° is 0.08 - 0.18°, preferably, 0.08 - 0.15°. (2) The full width at half maximum FWHM of the diffraction peak with a diffraction angle 2θ value near 45° is 0.09 - 0.22°, preferably, 0.09 - 0.20°. (3) The positive electrode material for a sodium ion battery according to any one of Appendices 1 to 3, characterized in that the ratio of the intensity of the diffraction peak at a diffraction angle 2θ value of around 43° to the intensity of the diffraction peak at a diffraction angle 2θ value of around 45° is 0.1 to 12.0, preferably 0.1 to 10.0, more preferably 0.5 to 6.6, and even more preferably 4 to 6.6.

[0094] (Appendix 6) In the powder X-ray diffraction pattern of the positive electrode material for a sodium ion battery, there are three to five diffraction peaks at a diffraction angle 2θ value of 30 to 40°, Preferably, there are three diffraction peaks at a diffraction angle 2θ value of 30 to 40°, and the diffraction angle 2θ values ​​are respectively around 33°, around 35°, and around 36°, and preferably the diffraction angle 2θ values ​​are respectively around 33.3°, around 35.3°, and around 36.6°, Or, There are four diffraction peaks at diffraction angle 2θ values ​​of 30 to 40°, and the diffraction angle 2θ values ​​are respectively around 33°, around 35°, around 36°, and around 37°, and preferably the diffraction angle 2θ values ​​are respectively around 33.3°, around 35.3°, around 36.6°, and around 37.4°, Or, 4. The positive electrode material for a sodium ion battery according to any one of Appendices 1 to 3, characterized in that there are five diffraction peaks at diffraction angle 2θ values ​​of 30 to 40°, and the diffraction angle 2θ values ​​are respectively around 32°, around 33°, around 34°, around 35°, and around 37°, and preferably the diffraction angle 2θ values ​​are respectively around 31.7°, around 33.4°, around 34.5°, around 35.2°, and around 36.6°.

[0095] (Appendix 7) the mass percent content of Mn element in the sodium ion battery positive electrode material is 3 to 28%, preferably the mass percent content of Mn element is 4 to 25%, and more preferably the mass percent content of Mn element is 4 to 22%, and / or the mass percent content of the Fe element is 3-28%, preferably the mass percent content of the Fe element is 4-25%; and / or the mass percent content of the Ni element is 3-27%, preferably, the mass percent content of the Ni element is 5-25%, more preferably, the mass percent content of the Ni element is 7-24%.

[0096] (Appendix 8) 4. The positive electrode material for a sodium ion battery according to any one of claims 1 to 3, wherein the total content of residual alkali in the positive electrode material for a sodium ion battery is less than 3.5%, preferably less than 3.0%.

[0097] (Appendix 9) The specific surface area of ​​the positive electrode material for a sodium ion battery is 0.2 to 1.3 m 2 / g, and / or the particle size D50 of the positive electrode material for a sodium ion battery is 2 to 18 μm, preferably 3 to 15 μm; And / or, the tap density of the positive electrode material for a sodium ion battery is 1.0 to 2.9 g / cm 3 and preferably, the tap density of the positive electrode material for a sodium ion battery is 1.0 to 2.6 g / cm 3 4. The positive electrode material for a sodium ion battery according to any one of appendices 1 to 3, wherein:

[0098] (Appendix 10) Mixing a Na source, a Ni source, a Mn source, an Fe source, and an A source in a certain ratio, firing the mixture, cooling the mixture, and pulverizing the mixture to obtain a positive electrode material for a sodium ion battery; 4. The method for producing a positive electrode material for a sodium ion battery according to any one of appendices 1 to 3, wherein the mixing is performed by using a solid phase mixing method or a liquid phase mixing method.

[0099] (Appendix 11) The calcination is divided into two steps, in which in step 1, the raw material is pretreated at a calcination temperature of 450 to 650°C, and / or the calcination time is 3 to 10 hours, and in step 2, the calcined raw material is calcined at a temperature of 850 to 950°C, and / or the calcination time is 8 to 40 hours; Preferably, the method for producing a positive electrode material for a sodium ion battery according to Appendix 10 is characterized in that the temperature is increased to the baking temperature of Step 1 at a rate of 1 to 10°C / min and then constant-temperature baking is performed, and / or the temperature is increased to the baking temperature of Step 2 at a rate of 1 to 10°C / min and then constant-temperature baking is performed.

[0100] (Appendix 12) 11. The method for producing a positive electrode material for a sodium ion battery according to claim 10, wherein the distance between the grinding disks is 0 to 2 mm and the rotation speed is 500 to 3000 rpm, preferably the distance between the grinding disks is 0 to 1.5 mm and the rotation speed is 1000 to 2800 rpm.

[0101] (Appendix 13) 11. The method for producing a positive electrode material for a sodium ion battery according to claim 10, wherein the sodium source is one or more selected from the group consisting of sodium hydroxide, sodium carbonate, sodium nitrate, sodium oxalate, sodium chloride, sodium fluoride, and sodium acetate.

[0102] (Appendix 14) the A source is selected from oxides of one or more elements selected from the group consisting of Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu, or salts thereof, or organic compounds thereof; Preferably, the A source is selected from carbonates, oxalates, nitrates, or oxides of one or more elements selected from the group consisting of Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu; More preferably, the A source is one or more selected from zinc oxide, titanium dioxide, calcium oxide, copper oxide, aluminum oxide, yttrium oxide, diboron trioxide, barium oxide, niobium oxide, magnesium oxide, and zirconium oxide.

[0103] (Appendix 15) A sodium ion positive electrode material produced by the method for producing a sodium ion battery positive electrode material according to claim 10.

[0104] (Appendix 16) A positive electrode for a sodium ion battery, comprising at least one of the positive electrode materials for a sodium ion battery according to any one of Supplementary Notes 1 to 3 or Supplementary Note 15 as a positive electrode active material.

[0105] (Appendix 17) A sodium ion battery comprising the positive electrode of the sodium ion battery according to claim 16, a negative electrode, and a sodium salt-containing electrolyte.

[0106] (Appendix 18) 23. A photovoltaic system, a power system, an energy storage system or a mobile storage device, or a low-end electric vehicle, comprising the sodium-ion battery of claim 22.

Claims

1. A positive electrode material for a sodium ion battery, comprising: The general formula of the positive electrode material is Na 1+a Ni 1-x-y-z Mn x Fe y A z O 2 , and the A element contains Zn element and M element, where the content of Zn element is represented by b, and the total content of Zn element and M element is z. １＋ａ Ni １－ｘ－ｙ－ｚ Mn ｘ Fe ｙ Zn ｂ M ｚ－ｂ O ２ wherein, in the formula, −0.40≦a≦0.20, 0.08<x<0.48, 0.05<y<0.45, 0.01<z<0.24, 0<b≦0.10, and M is selected from a combination of two or more of Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu elements; And / or, the A element contains Ti element and N element, wherein the content of Ti element is represented by c, the total content of Ti element and N element is z, and the general formula of the positive electrode material is Na １＋ａ Ni １－ｘ－ｙ－ｚ Mn ｘ Fe ｙ Ti ｃ N ｚ－ｃ O ２ wherein, in the formula, −0.40≦a≦0.20, 0.08<x<0.48, 0.05<y<0.45, 0.01<z<0.24, 0<c<0.24, and N is selected from a combination of two or more of Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu elements; And / or, the A element contains Ti element, Zn element and X element, wherein the content of Zn element is represented by b, the content of Ti element is represented by c, and the total content of Ti element, Zn element and X element is z, and the general formula of the positive electrode material is Na １＋ａ Ni １－ｘ－ｙ－ｚ Mn ｘ Fe ｙ Zn ｂ Ti ｃ X ｚ－ｂ－ｃ O ２ wherein, in the formula, −0.40≦a≦0.20, 0.08<x<0.48, 0.05<y<0.45, 0.01<z<0.24, 0<b≦0.1, 0≦c<0.24, and X is selected from a combination of two or more of Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu elements; However, in the sodium ion battery positive electrode material, there are at least two diffraction peaks in the diffraction angle 2θ value range of 42 to 46°, and the diffraction angle 2θ values ​​of the two diffraction peaks are near 43° and near 45°, respectively; The positive electrode material for a sodium ion battery is characterized in that the total content of residual alkali in the positive electrode material for a sodium ion battery is less than 3.5%.

2. The powder X-ray diffraction pattern of the positive electrode material for a sodium ion battery is α-NaFeO ２ 2. The positive electrode material for a sodium ion battery according to claim 1, characterized in that it exhibits a type layer structure.

3. In the powder X-ray diffraction pattern of the sodium ion battery positive electrode material, the full width at half maximum (FWHM) of two diffraction peaks having a diffraction angle 2θ value of 42 to 46° is 0.06 to 0.3°, And / or, the lattice spacing of two diffraction peaks having a diffraction angle 2θ value of 42 to 46° is 1.5 to 3.0 Å.

4. In the powder X-ray diffraction pattern of the sodium ion battery positive electrode material, the full width at half maximum (FWHM) of two diffraction peaks having a diffraction angle 2θ value of 42 to 46° is 0.06 to 0.25°, And / or, the lattice spacing of two diffraction peaks having a diffraction angle 2θ value of 42 to 46° is 1.8 to 2.8 Å.

5. 5. The positive electrode material for a sodium ion battery according to claim 4, wherein in a powder X-ray diffraction pattern of the positive electrode material for a sodium ion battery, the lattice spacing of two diffraction peaks having a diffraction angle 2θ value of 42 to 46° is 1.8 to 2.3 Å.

6. In the powder X-ray diffraction pattern of the positive electrode material for a sodium ion battery, the full width at half maximum (FWHM) of a diffraction peak has one or more of the following characteristics: (1) The full width at half maximum (FWHM) of the diffraction peak at a diffraction angle 2θ value of approximately 43° is 0.08 to 0.18°, (2) The full width at half maximum (FWHM) of the diffraction peak at a diffraction angle 2θ value of approximately 45° is 0.09 to 0.22°, (3) The positive electrode material for a sodium ion battery according to claim 1, characterized in that the ratio of the intensity of the diffraction peak having a diffraction angle 2θ value of about 43° to the intensity of the diffraction peak having a diffraction angle 2θ value of about 45° is 0.1 to 12.

0.

7. In the powder X-ray diffraction pattern of the positive electrode material for a sodium ion battery, the full width at half maximum (FWHM) of a diffraction peak has one or more of the following characteristics: (1) The full width at half maximum (FWHM) of the diffraction peak at a diffraction angle 2θ value of approximately 43° is 0.08 to 0.15°, (2) The full width at half maximum (FWHM) of the diffraction peak at a diffraction angle 2θ value of approximately 45° is 0.09 to 0.20°, (3) The positive electrode material for a sodium ion battery according to claim 6, characterized in that the ratio of the intensity of the diffraction peak having a diffraction angle 2θ value of about 43° to the intensity of the diffraction peak having a diffraction angle 2θ value of about 45° is 0.1 to 10.

0.

8. The positive electrode material for a sodium ion battery according to claim 7, characterized in that the ratio of the intensity of a diffraction peak having a diffraction angle 2θ value of about 43° to the intensity of a diffraction peak having a diffraction angle 2θ value of about 45° is 0.5 to 6.

6.

9. The positive electrode material for a sodium ion battery according to claim 8, characterized in that the ratio of the intensity of a diffraction peak having a diffraction angle 2θ value of about 43° to the intensity of a diffraction peak having a diffraction angle 2θ value of about 45° is 4 to 6.

6.

10. 2. The positive electrode material for a sodium ion battery according to claim 1, wherein the powder X-ray diffraction pattern of the positive electrode material for a sodium ion battery has three to five diffraction peaks at a diffraction angle 2θ value of 30 to 40°.

11. There are three diffraction peaks at a diffraction angle 2θ value of 30 to 40°, and the diffraction angle 2θ values ​​are around 33°, around 35°, and around 36°, respectively. Or, There are four diffraction peaks at diffraction angle 2θ values ​​of 30 to 40°, and the diffraction angle 2θ values ​​are around 33°, around 35°, around 36°, and around 37°, respectively. Or, 11. The positive electrode material for a sodium ion battery according to claim 10, characterized in that there are five diffraction peaks at diffraction angle 2θ values ​​of 30 to 40°, and the diffraction angle 2θ values ​​are respectively around 32°, around 33°, around 34°, around 35°, and around 37°.

12. There are three diffraction peaks at a diffraction angle 2θ value of 30 to 40°, and the diffraction angle 2θ values ​​are around 33.3°, around 35.3°, and around 36.6°, respectively. Or, There are four diffraction peaks at a diffraction angle 2θ value of 30 to 40°, and the diffraction angle 2θ values ​​are respectively around 33.3°, around 35.3°, around 36.6°, and around 37.4°, or 11. The positive electrode material for a sodium ion battery according to claim 10, characterized in that there are five diffraction peaks at a diffraction angle 2θ value of 30 to 40°, and the diffraction angle 2θ values ​​are respectively around 31.7°, around 33.4°, around 34.5°, around 35.2°, and around 36.6°.

13. The mass percent content of Mn element in the sodium ion battery positive electrode material is 3 to 28%, and / or the mass percent content of the Fe element is 3 to 28%; And / or, the mass percent content of the Ni element is 3 to 27%.

14. The mass percent content of Mn element in the sodium ion battery positive electrode material is 4 to 25%, and / or the mass percent content of the Fe element is 4 to 25%; And / or the mass percent content of the Ni element is 5 to 25%.

15. The mass percent content of Mn element in the sodium ion battery positive electrode material is 4 to 22%, And / or the mass percent content of the Ni element is 7 to 24%.

16. 2. The positive electrode material for a sodium ion battery according to claim 1, wherein the total content of residual alkali in the positive electrode material for a sodium ion battery is less than 3.0%.

17. The specific surface area of ​​the positive electrode material for a sodium ion battery is 0.2 to 1.3 m ２ / g, and / or the particle size D50 of the sodium ion battery positive electrode material is 2 to 18 μm; And / or the tap density of the positive electrode material for a sodium ion battery is 1.0 to 2.9 g / cm ３ The positive electrode material for a sodium ion battery according to claim 1,

18. mixing a Na source, a Ni source, a Mn source, an Fe source, and an A source in a certain ratio, firing the mixture, cooling, and pulverizing the mixture to obtain a positive electrode material for a sodium ion battery; However, the mixing is performed by using a solid phase mixing method or a liquid phase mixing method, The method for producing a positive electrode material for a sodium ion battery according to any one of claims 1 to 17, characterized in that the calcination is divided into two steps, and in step 1, the raw materials are pretreated at a calcination temperature of 450 to 650°C, and / or the calcination time is 3 to 10 hours, and in step 2, the calcined raw materials are calcined at a temperature of 850 to 950°C, and / or the calcination time is 8 to 40 hours.

19. The method for producing a positive electrode material for a sodium ion battery according to claim 18, characterized in that the temperature is increased to the baking temperature of step 1 at a temperature increase rate of 1 to 10 ° C. / min and then constant temperature baking is performed, and / or the temperature is increased to the baking temperature of step 2 at a temperature increase rate of 1 to 10 ° C. / min and then constant temperature baking is performed.

20. The method for producing a positive electrode material for a sodium ion battery according to claim 18, characterized in that the distance between the grinding disks is 0 to 2 mm, and the rotation speed is 500 to 3000 rpm.

21. The method for producing a positive electrode material for a sodium ion battery according to claim 20, wherein the distance between the disks is 0 to 1.5 mm, and the rotation speed is 1000 to 2800 rpm.

22. 19. The method for producing a positive electrode material for a sodium ion battery according to claim 18, wherein the sodium source is one or more selected from the group consisting of sodium hydroxide, sodium carbonate, sodium nitrate, sodium oxalate, sodium chloride, sodium fluoride, and sodium acetate.

23. 19. The method for producing a positive electrode material for a sodium ion battery according to claim 18, wherein the A source is selected from oxides of one or more elements selected from the group consisting of Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu, or salts thereof, or organic compounds thereof.

24. 24. The method for producing a positive electrode material for a sodium ion battery according to claim 23, wherein the A source is selected from carbonates, oxalates, nitrates, and oxides of one or more elements selected from the group consisting of Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, and Cu.

25. 25. The method for producing a positive electrode material for a sodium ion battery according to claim 24, wherein the A source is one or more selected from zinc oxide, titanium dioxide, calcium oxide, copper oxide, aluminum oxide, yttrium oxide, diboron trioxide, barium oxide, niobium oxide, magnesium oxide, and zirconium oxide.

26. A positive electrode for a sodium ion battery, comprising at least one positive electrode material for a sodium ion battery according to any one of claims 1 to 17 as a positive electrode active material.

27. A sodium ion battery comprising the positive electrode of the sodium ion battery according to claim 26, a negative electrode, and a sodium salt-containing electrolyte.

28. 28. A photovoltaic system, a power system, an energy storage system or mobile storage device, or a low-end electric vehicle, comprising the sodium-ion battery of claim 27.

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