Cathode material for sodium ion battery with protective layer, and preparation method and use thereof

Abstract

To provide a cathode material for a sodium ion battery which is structurally stable, and has a surface coating layer inhibiting side reactions with an electrolyte, so that the cycling performance is significantly improved.SOLUTION: A sodium cathode material having a coating structure has general chemical formula: Na1+aNixMnyFezAmBnO2, where -0.35≤a≤0.20, 0.08<x≤0.5, 0.05<y≤0.48, 0.03<z<0.4, 0.03<m<0.24, 0.001<n<0.06, and x+y+z+m+n=1. A preparation method of the cathode material for a sodium ion battery comprises the steps of: firstly, mixing a sodium source, a nickel source, a manganese source, an iron source and an A source uniformly, and then performing a first sintering, cooling and crushing to obtain a semi-finished product; then, after mixing the semi-finished product with a B source uniformly, performing a second sintering, cooling and crushing to obtain the sodium ion cathode material.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention belongs to the technical field of sodium ion batteries, and specifically relates to a sodium ion battery positive electrode material, its preparation method and application. [Background technology]

[0002] Concerns about the Earth's lithium resources and the demand for new scale energy storage applications are driving the development of new battery fields. With extensive experience in lithium-ion batteries, sodium-ion batteries are rapidly being developed. The main cathode materials for sodium-ion batteries are layered and tunnel-type transition metal oxides, polyanion compounds, Prussian blue analogues, organic materials, etc. In addition to research into these systems, efforts are also being made to reduce the cost and commercialize the development of sodium-ion batteries. In 2011, Komaba et al. in Japan reported the development of a hard carbon |NaNi 0.5 Mn 0.5 In the same year, the world's first sodium-ion battery company, FARADION, was established in the UK. In 2013, American Goodenough et al. proposed a Prussian white cathode material with higher voltage and excellent rate performance. In 2014, Chinese Hu Yongsheng et al. 3+ / Cu 2+ We discovered the electrochemical activity of redox couples for the first time and devised a series of low-cost Cu-based cathode materials.

[0003] Positive electrode oxides for sodium-ion batteries mainly include layered structure oxides and tunneled structure oxides. The crystalline structure of tunneled structure oxides has a unique "S"-shaped channel, which allows for good rate performance and greater stability against air and water, but a lower initial charge / discharge specific capacity, resulting in a smaller practical specific capacity. Layered structure oxides have a periodic layered structure, are simple to manufacture, and have relatively high specific capacity and voltage, making them the primary positive electrode material for sodium-ion batteries. To prevent sodium loss during the manufacturing process, excess sodium salts are often added during the material manufacturing process. As a result, sodium salts remain after sintering, mainly in the form of sodium carbonate and sodium hydroxide, abbreviated as "free sodium." If the alkalinity of the cathode material for sodium-ion batteries is too high, the material will easily absorb water and become susceptible to moisture during processing, increasing viscosity and forming a gel during the slurrying process, resulting in poor processing performance. Sodium-ion layered oxides typically have MO6 octahedral structures formed by transition metal elements and six surrounding oxygen atoms, with sodium ions positioned between the transition metal layers, forming a layered structure with alternating MO6 polyhedral layers and NaO6 alkali metal layers. This structure causes lattice distortion and phase transitions during the charge and discharge process of sodium ions, inhibiting their transport and diffusion. 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, poor cycling performance, battery performance degradation or even failure, and safety concerns. Summary of the Invention [Problem to be solved by the invention]

[0004] The technical problems that the present invention aims to solve are as follows: In the charge and discharge process of the positive electrode material of the conventional sodium ion battery, lattice distortion is easily generated, and a phase transition occurs, which hinders the transport and diffusion of sodium ions, and most of the sodium ions are liberated on the surface of the material, which causes side reactions with the electrolyte, resulting in irreversible capacity loss, deterioration of cycle performance, and deterioration or failure of battery performance. [Means for solving the problem]

[0005] In response to the above technical problems, the present invention aims to provide a sodium ion battery positive electrode material, its preparation method and use, which has a relatively stable structure and relatively complete sodium ion site occupation within the material, and is also coated to modify the surface of the material, thereby forming an effective protective layer on the surface of the material, inhibiting side reactions between the material and the electrolyte, reducing irreversible capacity loss and improving the cycling performance of the material.

[0006] Specifically, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a sodium-ion battery cathode material having a coating structure, the cathode material having a general chemical formula of Na 1+a Ni x Mn y Fe z A m B n O2, where -0.35≦a≦0.20 and 0.08 <x≦0.5であり、0.05<y≦0.48であり、0.03<z<0.4であり、0.03<m<0.24であり、0.001<n<0.06であり、x+y+z+m+n=1であり、 wherein A is a modifying element, and the A element includes one or more of Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P and Cu elements; Here, the B element is an element in the coating layer, and the B element includes one or more of Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, and Cu.

[0008] In some embodiments, preferably the general chemical formula of the cathode material is Na 1+a Ni x Mn y Fez A m B n which is O2, where -0.35 ≤ a ≤ 0.20, 0.1 ≤ x ≤ 0.3, 0.1 ≤ y ≤ 0.4, 0.2 ≤ z ≤ 0.4, 0.05 ≤ m ≤ 0.2, 0.01 < n ≤ 0.05, and x + y + z + m + n = 1.

[0009] In some embodiments, preferably, the chemical general formula of the positive electrode material is Na 1+a Ni x Mn y Fe z A m [[ID=​​​​​​​​​​​​​​​​​​​​​In some embodiments, A comprises one or more of the elements Ti, Zn, Al, Zr, Y, Ca, Li, W, Ce, Mo, Ba, Mg, Ta, Nb, Sc, Sr, B, F, P, and Cu.

[0012] In some embodiments, A comprises one or more of the elements Ti, Zn, Al, Y, Ca, Zr, Li, Mg, Mn, Sr, F, B, and Cu.

[0013] In some embodiments, B comprises one or more of the elements Ti, Co, Mn, Al, Zr, Y, Li, Mg, B, F, P, and Cu.

[0014] In some embodiments, B is one or more combinations selected from the group consisting of the elements Mg, Zr, P, F, Al, Mg, Ti, and B.​​​​​​​​​​​​​​​​​​​​ In some embodiments, the M element is one or more selected from the group consisting of Mn, Ti, Al, Y, Ca, Mg, F, P, B, and Cu.

[0017] In some embodiments, A contains Ti element and N element, where the content of Ti element is represented by c, the total content of Ti element and N element is m, and the chemical general formula of the positive electrode material is Na 1+a Ni x Mn y Fe z Ti c N m-c B n O2, where -0.35 ≤ a ≤ 0.20, 0.08 < x ≤ 0.5, 0.05 < y ≤ 0.48, 0.03 < z < 0.4, 0.03 < m < 0.24, 0.001 < n < 0.06, x + y + z + m + n = 1, 0 < c < 0.24. Further preferably, -0.35 ≤ a ≤ 0.20, 0.1 ≤ x ≤ 0.3, 0.1 ≤ y ≤ 0.4, 0.2 ≤ z ≤ 0.4, 0.05 ≤ m ≤ 0.15, 0.01 < n ≤ 0.05, x + y + z + m + n = 1, 0 < c < 0.24. The N is one or more selected from the group consisting of Ti, Zn, Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, and Cu elements.

[0018] In some embodiments, the N is one or more selected from the group consisting of Mn, Mg, F, Li, Zn, Al, Y, Ca, B, and Cu elements.

[0019] ​​​​​​​​​​​​​​m-d-e B n It is O₂, -0.35 ≤ a ≤ 0.20, 0.08 < x ≤ 0.5, 0.05 < y ≤ 0.48, 0.03 < z < 0.4, 0.03 < m < 0.24, 0.001 < n < 0.06, x + y + z + m + n = 1, 0 < d ≤ 0.1, 0 < e < 0.24. Further preferably, -0.35 ≤ a ≤ 0.20, 0.1 ≤ x ≤ 0.3, 0.1 ≤ y ≤ 0.4, 0.2 ≤ z ≤ 0.4, 0.05 ≤ m ≤ 0.15, 0.01 < n ≤ 0.05, 0 < d ≤ 0.1, 0 < e < 0.24, x + y + z + m + n = 1. The X is one or a combination of two or more selected from the group consisting of Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, and Cu elements.

[0020] In some embodiments, the X is one or a combination of two or more selected from the group consisting of Co, Mn, Al, Zr, Y, Ca, Li, W, Ba, Mg, Nb, B, F, P, and Cu elements.

[0021] In some embodiments, in the X-ray diffraction spectrum of the sodium ion battery cathode material powder, the diffraction angle 2θ value has at least two diffraction peaks between 41° and 46°.

[0022] In some embodiments, the full width at half maximum FWHM of the two diffraction peaks between 41° and  46° of the diffraction angle 2θ value is 0.07° to 0.29°.

[0023] In some embodiments, the interplanar spacing of the two diffraction peaks between 41° and 46° of the diffraction angle 2θ value is 1.85 Å to 2.75 Å.

[0024] In some embodiments, the diffraction angle 2θ value has two diffraction peaks between 41° and 46°, and the diffraction angle 2θ values of the two diffraction peaks are respectively near 41° and near 45°.

[0025] In some embodiments, the full width at half maximum (FWHM) of a diffraction peak at a diffraction angle 2θ value of around 41° is 0.07° to 0.17°.

[0026] In some embodiments, the full width at half maximum (FWHM) of a diffraction peak at a diffraction angle 2θ value of around 45° is 0.07° to 0.23°.

[0027] In some embodiments, the diffraction angle 2θ value has at least three diffraction peaks between 30° and 40°.

[0028] In some embodiments, there are three diffraction peaks with diffraction angle 2θ values ​​between 30° and 40°, and the diffraction angle 2θ values ​​are respectively around 33°, 35°, and 36°.

[0029] In some embodiments, there are four diffraction peaks between the diffraction angle 2θ values ​​of 30° and 40°, and the diffraction angle 2θ values ​​are respectively around 32°, 33°, 35°, and 36°.

[0030] In some embodiments, there are four diffraction peaks between the diffraction angle 2θ values ​​of 30° and 40°, and the diffraction angle 2θ values ​​are respectively around 33°, 35°, 36°, and 37°.

[0031] In some embodiments, there are four diffraction peaks between the diffraction angle 2θ values ​​of 30° and 40°, and the diffraction angle 2θ values ​​are respectively around 33°, 34°, 35°, and 36°.

[0032] In some embodiments, there are five diffraction peaks with diffraction angle 2θ values ​​between 30° and 40°, and the diffraction angle 2θ values ​​are respectively around 32°, 33°, 34°, 35°, and 36°.

[0033] In some embodiments, the ratio of the peak intensity of the (003) diffraction peak at a diffraction angle 2θ of about 16° to the peak intensity of the (104) diffraction peak at a diffraction angle 2θ of about 41° is 0.4 to 1.4.

[0034] In some embodiments, the ratio of the peak intensity of the (003) diffraction peak at a diffraction angle 2θ of about 16° to the peak intensity of the (104) diffraction peak at a diffraction angle 2θ of about 41° is 0.45 to 1.2.

[0035] In some embodiments, the specific surface area of ​​the sodium-ion battery cathode material is 0.2 to 1.2 m 2 / g.

[0036] In some embodiments, the specific surface area of ​​the sodium-ion battery cathode material is 0.4 to 1 m 2 / g.

[0037] In some embodiments, the particle size D50 of the sodium-ion battery cathode material is 2 to 18 μm.

[0038] In some embodiments, the particle size D50 of the sodium-ion battery cathode material is 3 to 15 μm.

[0039] In some embodiments, the particle size D50 of the sodium-ion battery cathode material is 5-11 μm.

[0040] In some embodiments, the tap density of the sodium-ion battery cathode material is 1.2 to 2.9 g / cm 3 is.

[0041] In some embodiments, the tap density of the sodium-ion battery cathode material is 1.2 to 2.6 g / cm 3 is.

[0042] In some embodiments, the sodium-ion battery cathode material powder X-ray diffraction spectrum shows an α-NaFeO 2 -type layered structure.

[0043] In some embodiments, the sodium-ion battery cathode material has a total free sodium content of 2.3% or less.

[0044] In some embodiments, the sodium-ion battery cathode material has a total free sodium content of 2.0% or less.

[0045] In a second aspect, the present invention provides a method for producing the above sodium-ion battery cathode material, a step (1) of uniformly mixing a sodium source, a nickel source, a manganese source, an iron source, and an A source, followed by a first sintering, cooling, and pulverizing to obtain a semi-finished product; and (2) uniformly mixing the semi-finished product and the B source, followed by a second sintering, cooling, and pulverizing to obtain a sodium ion positive electrode material.

[0046] In some embodiments, in step (1), the sodium source, nickel source, manganese source, iron source, and A source are mixed using a solid-phase mixing method.

[0047] In some embodiments, in step (1), the solid-phase mixing method involves adding the sodium source, nickel source, manganese source, iron source, and A source to a blender and mixing them in proportions, wherein the mixing rotation speed is 4,000 to 25,000 rpm and the mixing time is 10 to 50 minutes.

[0048] In some embodiments, in step (2), the semi-finished product and the B source are mixed using a solid-phase mixing method.

[0049] In some embodiments, in step (2), the semi-finished product and the B source are mixed by a ball mill mixing method.

[0050] In some embodiments, in step (2), the solid-phase mixing method is to uniformly mix the semi-finished product obtained in step (1) with the B source according to a molar ratio, and then add the mixture to a ball mill to perform ball mill mixing, wherein the ball mill mixing time is 8 to 30 minutes, and / or the ball mill frequency is 40 to 55 Hz.

[0051] In some embodiments, in step (1), the conditions for the first sintering are as follows: a heating rate of 3 to 5°C / min, a temperature of 780 to 980°C, and a time of 8 to 30 hours; In some embodiments, in step (2), the conditions for the second sintering are as follows: a temperature rise rate of 6 to 9° C. / min, a temperature of 180 to 850° C., and a time of 2 to 10 hours.

[0052] In some embodiments, in step (1), the spacing of the grinding disc mill is 0 to 2 mm, and / or the rotation speed is 500 to 3000 r / min.

[0053] In some embodiments, in step (1), the spacing of the grinding disc mill is 0 to 1.5 mm, and / or the rotation speed is 1000 to 2800 r / min.

[0054] In some embodiments, in step (2), the spacing of the grinding disc mill is 0 to 2 mm, and / or the rotation speed is 500 to 3000 r / min.

[0055] In some embodiments, in step (2), the spacing of the grinding disc mill is 0 to 1.5 mm, and / or the rotation speed is 1000 to 2800 r / min.

[0056] In some embodiments, the atmosphere for the first sintering is an oxygen-containing gas.

[0057] In some embodiments, the atmosphere for the first sintering is air, oxygen, or a mixture thereof; In some embodiments, the atmosphere for the second sintering is an oxygen-containing gas.

[0058] In some embodiments, the atmosphere for the second sintering is air, oxygen, or a mixture thereof.

[0059] In some embodiments, the Na source comprises one or more of sodium hydroxide, sodium carbonate, sodium nitrate, sodium oxalate, sodium chloride, sodium fluoride, and sodium acetate.

[0060] In some embodiments, the A source is an oxide 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, a salt thereof, or an organic substance thereof; In some embodiments, the A source is a carbonate, oxalate, nitrate, or oxide 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; In some embodiments, the A source comprises one or more of zinc oxide, titanium dioxide, calcium oxide, copper oxide, aluminum oxide, yttrium trioxide, boron trioxide, barium oxide, niobium oxide, magnesium oxide, and zirconium oxide.

[0061] In some embodiments, the B source is one or more oxides, salts, or organic substances thereof selected from the group consisting of Ti, Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, and Cu elements; In some embodiments, the B source is a carbonate, oxalate, nitrate, or oxide of one or more elements selected from the group consisting of Ti, Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, and Cu; In some embodiments, the B source comprises one or more of magnesium oxide, aluminum oxide, titanium oxide, magnesium acetate, aluminum acetate, aluminum nitrate, boric acid, and boron oxide.

[0062] In some embodiments, a sodium-ion battery cathode material is produced by the method for producing a sodium-ion battery cathode material described above.

[0063] In a third aspect, the present invention provides a sodium-ion battery cathode, the sodium-ion battery cathode comprising the sodium-ion battery cathode material described above as an active cathode material.

[0064] In a fourth aspect, the present invention provides a sodium-ion battery, the sodium-ion battery comprising the sodium-ion battery positive electrode described above, a negative electrode, and an electrolyte comprising a sodium salt.

[0065] In a fifth aspect, the sodium-ion battery is used as a power source in a solar, electric, energy storage system or mobile storage device or low-end electric vehicle.

[0066] In some embodiments, the sodium-ion batteries are used in distributed energy storage, centralized energy storage, or low-end power battery energy storage devices.

[0067] In a fifth aspect, the present invention provides a power system, an energy storage system or a mobile storage device manufactured with the sodium-ion battery described above. [Effects of the Invention]

[0068] The present invention is 1+a Ni x Mn y Fe z A m B nA sodium-ion battery cathode material with the chemical formula O2 is provided. On the one hand, the addition of modifying element A improves the structural stability of the material, forming a special XRD structure, providing stable channels for sodium ion transport and allowing the sodium ions to be sufficiently transported and diffused inside the material, thereby reducing the amount of free sodium ions on the material surface. On the other hand, the coating of element B modifies the surface of the material, forming an effective protective layer on the surface of the material, inhibiting side reactions between the material and the electrolyte, reducing irreversible capacity loss, and improving the cycling performance of the material. [Brief explanation of the drawings]

[0069] [Figure 1] FIG. 1 is an XRD diagram of a sodium ion positive electrode material in Example 1. [Figure 2] 1 is a cycle graph of the sodium ion positive electrode material in Example 1. [Figure 3] FIG. 1 is an XRD diagram of a sodium ion positive electrode material in Example 2. [Figure 4] 1 is a cycle graph of a sodium ion positive electrode material in Example 2. [Figure 5] FIG. 10 is an XRD diagram of a sodium ion positive electrode material in Example 3. [Figure 6] 1 is a cycle graph of a sodium ion positive electrode material in Example 3. [Figure 7] FIG. 10 is an XRD diagram of a sodium ion positive electrode material in Example 4. [Figure 8] 1 is a cycle graph of a sodium ion positive electrode material in Example 4. [Figure 9] FIG. 10 is an XRD diagram of a sodium ion positive electrode material in Example 5. [Figure 10] 10 is a cycle graph of the sodium ion positive electrode material in Example 5. [Figure 11] FIG. 10 is an XRD diagram of a sodium ion positive electrode material in Example 6. [Figure 12] 10 is a cycle graph of the sodium ion positive electrode material in Example 6. [Figure 13] FIG. 1 is an XRD diagram of a sodium ion positive electrode material in Comparative Example 1. [Figure 14] 1 is a cycle graph of a sodium ion positive electrode material in Comparative Example 1. [Figure 15] FIG. 10 is an XRD diagram of a sodium ion positive electrode material in Comparative Example 2. [Figure 16] 1 is a cycle graph of a sodium ion positive electrode material in Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0070] As described above, an object of the present invention is to provide a sodium ion battery positive electrode material, a method for producing the same, and uses thereof.

[0071] In one specific embodiment of the present invention, a sodium-ion battery cathode material having a coating structure is provided, wherein the general chemical formula of the cathode material is Na 1+a Ni x Mn y Fe z A m B n O2, where -0.35≦a≦0.20 and 0.08 <x≦0.5であり、0.05<y≦0.48であり、0<z<0.4であり、0<m<0.24であり、0.0<n<0.06であり、x+y+z+m+n=1であり、 wherein A is a modifying element, and the A element includes one or more of Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P and Cu elements; Here, the B element is an element in the coating layer, and the B element includes one or more of Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, and Cu.

[0072] In one specific embodiment of the present invention, a method for producing a sodium-ion battery cathode material is provided, comprising: a step (1) of uniformly mixing a sodium source, a nickel source, a manganese source, an iron source, and an A source by a solid-phase mixing method, followed by a first sintering, in which the sintering atmosphere is an oxygen-containing gas, and the sintering conditions are as follows: a temperature rise rate of 3 to 5°C / min, a temperature of 780 to 980°C, and a time of 8 to 30 hours; and cooling and pulverizing the mixture to obtain a semi-finished product; and (2) a step of uniformly mixing the semi-finished product and the B source by a ball mill mixing method, followed by a second sintering, in which the sintering atmosphere is an oxygen-containing gas, and the sintering conditions are as follows: a heating rate of 6-9°C / min, a temperature of 180-850°C, and a time of 2-10 hours; cooling and pulverizing the mixture to obtain a sodium ion positive electrode material having a coating structure.

[0073] (definition) The semi-finished product according to the present invention is a product obtained by uniformly mixing a sodium source, a nickel source, a manganese source, an iron source, and an A source and then sintering, i.e., an oxide containing a sodium source, a nickel source, a manganese source, an iron source, and an A source. The molecular formula of the semi-finished product can be obtained by testing using an ICP (inductively coupled plasma spectrometer).

[0074] In the present invention, A is mainly doped into the crystalline structure as a modifying element, which stabilizes the crystalline structure and improves the cycle performance. The semi-finished product is mixed with the B source and sintered. The B source diffuses or migrates to the surface of the crystalline structure of the semi-finished product to form a coating layer, and the surface of the semi-finished product is further coated with the oxide of B element, which solves the interface problem of the positive electrode material, reduces the occurrence of side reactions, and further improves the cycle performance.

[0075] 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. In the present invention, a diffraction angle of around X° indicates that the diffraction angle is X°±1°, for example, around 16° indicates that the diffraction angle is 16°±1°, that is, 15° to 17°.

[0076] All raw materials and reagents used in the present invention were purchased from mainstream manufacturers. Those without manufacturer's specifications or concentration specifications are all routinely available and are not particularly limited as long as they achieve the desired effect. All instrumentation and equipment used in the present examples were purchased from major manufacturers and are not particularly limited as long as they achieve the desired effect. Unless specific techniques or conditions are specified in the present examples, the techniques or conditions are based on the techniques or conditions described in literature in the field or on the product specifications. The raw materials and equipment materials used in the examples and comparative examples of the present invention are listed in Table 1.

[0077] [Table 1]

[0078] In the examples of the present invention, the specific surface area of ​​the sodium ion positive electrode material is tested in accordance with the People's Republic of China Standard GB / T19587-2006, Method for determining the specific surface area of ​​solids by gas adsorption BET method. The analytical instrument was a Tristar II 3020 fully automatic specific surface and porosimeter. The test parameters were: adsorbate N2 99.999%, coolant liquid nitrogen, P0 actual measurement, volumetric measurement mode, adsorption pressure deviation 0.05 mmHg, equilibration time 5 s, relative pressure point selection P / P0: 0.05; 0.1; 0.15; 0.2; 0.25; 0.30. Sample preparation: An empty sample tube with stopper and mass recorder M1 was weighed, and a sample volume of 3.8-4.2 g was added to a 9.5 mm gauge pipe with a 3 / 8 inch vesicle. The tube was set to 200 °C using a FlowPrep 060 degassing station and heated and degassed with an inert gas purge for 0.5 h. The tube was then removed and cooled to room temperature. The sample tube with stopper and mass recorder M2 was weighed, and the sample mass M = M2 - M1. The BET value was recorded via on-machine testing.

[0079] The tap density (TD) test for the sodium ion cathode material in the examples of the present invention is performed in accordance with the People's Republic of China standard GB / T5162-2006, Method for Measuring Tap Density of Metal Powders. Test equipment: ZS-202 tap density meter. TD test parameters: vibration count 3000 times, vibration frequency 250±10 times / min, amplitude 3±0.1 mm, sample precision 50±0.5 g, precision of 100 mL tapping cylinder 1 mL, reading method: maximum and minimum volumes are read to obtain the arithmetic mean value, calculation formula: ρ=m / V, and the result is rounded to two decimal places.

[0080] The particle size testing of the sodium ion cathode material in the present embodiment was performed in accordance with the People's Republic of China standard GB / T19077-2016, Laser Diffraction Method for Particle Size Distribution. Testing equipment: Malvern Master Size 2000 laser particle size analyzer. Testing steps: 1 g of powder was weighed and added to 60 ml of pure water. The external ultrasonic wave was applied for 5 minutes. The sample was then placed in a sample injector and tested. The test data was recorded. Testing conditions: The testing principle was Mie theory, the detection angle was 0-135°, the external ultrasonic wave intensity was 40 kHz and 180 watts, the particle refractive index was 1.692, the particle absorption coefficient was 1, the sample test time was 6 seconds, the background test snap count was 6000 times, and the light blocking rate was 8-12%.

[0081] Here, the test method for free sodium (residual alkali) in the sodium ion positive electrode material in the embodiment of the present invention is as follows: accurately weigh 30 g ± 0.01 g of sample, place the sample in a 250 mL Erlenmeyer flask, add a magnetic element, add 100 mL of deionized water, place on a magnetic stirrer, start the stirrer and stir for 30 minutes, filter the mixed solution with qualitative filter paper and a funnel, take 1 mL of the filtrate and place it in a 100 mL beaker, add a magnetic element, place the beaker on a magnetic stirrer, add 2 drops of phenolphthalein indicator and titrate with 0.05 mol / L hydrochloric acid standard titration solution (V 初= 0), and titrate the 0.05 mol / L hydrochloric acid standard solution until the solution changes from red to colorless (end point 1, V1 = V 終1 -V 初 ), add two drops of methyl red indicator, and titrate with 0.05 mol / L hydrochloric acid standard titration solution until the solution changes from colorless to yellow and from yellow to orange. Place the beaker in a heating furnace and heat until the solution boils (until the solution changes from orange to yellow). Remove the beaker and cool to room temperature. Place the beaker on a magnetic stirrer and titrate with 0.05 mol / L hydrochloric acid standard titration solution until the solution changes from yellow to pale red. Record the volume V2 of the 0.05 mol / L hydrochloric acid standard titration solution (end point 2, V2 = V 終2 -V 終1 ) is recorded.

[0082] The formula for calculating free sodium content is as follows:

number

[0083] The XRD test of the sodium ion cathode material in the present embodiment was performed using an X'PertPRO MPD analyzer. Test conditions were as follows: the light pipe was a Cu target material, the wavelength was 1.54060, and the window was a Be window; the incident light path was a 0.04 rad sol-slit, a 1 / 2° divergence slit, a 10 mm shading plate, and a 1° anti-scattering slit; the diffraction light path was an 8.0 mm anti-scattering slit, a 0.04 rad sol-slit, and a large Ni filter; the scanning range was 10° to 90°, the scanning step size was 0.013°, and the dwell time for each step was 30.6 s; 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 should be polished to <50 μm). Place one edge of the blade (>20 mm) against the surface of the glass slide, slightly lift the other edge (at an included angle <10°), and use the edge of the blade to flatten the surface of the powder sample. Rotate the glass slide 90°, flatten it again, and repeat this process in both directions until the sample surface is texture-free. Remove any excess powder around the glass slide, and place it in the powder diffraction analyzer. Sample analysis: Open the sample file to be tested in High-Score Plus analysis software. First, determine the background, select peak search, confirm peaks, repeat fitting, select the corresponding phase, perform phase matching, and perform cell refinement. Record the cell parameters. Test principle: The Bragg equation reflects the relationship between the direction of the diffraction line and the crystal structure. For diffraction to occur, Bragg's equation, 2dsinθ=nλ (d: interplanar spacing, θ: Bragg angle, λ: wavelength of the X-ray, and n: number of reflection steps) 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, generating a strong X-ray diffraction line in a specific direction. When X-rays are irradiated onto a sample from different angles, they are diffracted by different crystal planes, and the detector receives the number of diffracted photons reflected from those crystal planes, thereby obtaining a spectrum showing the relationship between angle and intensity.

[0084] In the present embodiment, the element content of the sodium ion cathode material and the semi-finished product is tested by inductively coupled plasma (ICP) technology. The detection equipment is an ICP-OES iCAP 6300 inductively coupled plasma optical emission spectrometer. The detection conditions are: detector unit count >290,000, detector cooling system camera temperature <-35°C, optical system optical chamber temperature: 38±0.1°C, optical system wavelength range 166nm~847nm, plasma observation method is vertical observation, plasma observation height 14mm, RF power 1150W, frequency 27.12MHz, sample system auxiliary gas flow rate 0.5L / min, sample system nebulization gas flow rate 0.6L / min, and pump speed 50rpm. Microtest steps: Accurately weigh 0.2000-0.2100 g of sample into a 50 mL quartz beaker, add 10 mL of 1:1 aqua regia, cover the surface dish, and dissolve completely in a heating oven. Transfer to a 50 mL measuring flask, adjust to the specified volume, shake, and perform an on-machine test and record the data. Main measurement: Transfer 1 mL of the above mixed solution into a 100 mL measuring flask, adjust to the specified volume, shake, and perform an on-machine test and record the data.

[0085] The sodium ion battery of the present invention comprises an electrode, an electrolyte, a separator, and an aluminum plastic film. Specifically, the electrode includes a positive electrode and a negative electrode. The positive electrode is made of a positive electrode current collector and a material including a positive electrode active material, a binder, a conductive additive, etc. coated on the positive electrode current collector. The positive electrode active material is the sodium ion positive electrode material having the coating structure of the present invention. The negative electrode is made of a current collector and a material including a negative electrode active material, a binder, a conductive additive, etc. coated on the current collector. The separator is a PP / PE film commonly used in the industry and is used to separate the positive electrode and negative electrode from each other. The aluminum plastic film is a container for the positive electrode, negative electrode, separator, and electrolyte.

[0086] The binder in the present invention is primarily used to improve the binding between positive electrode active material particles and between the positive electrode active material particles and the current collector. The binder in the present invention may be a commercially available binder commonly used in the art. Specifically, the binder may be selected from polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, or a composition thereof.

[0087] The conductive additive in the present invention may be selected from commercially available conventional conductive additives 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 powders or metal fibers containing copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives), or compositions thereof.

[0088] In the following examples, the specific operation method for preparing a sodium ion button battery using the positive electrode material of the present invention is as follows: Positive electrode preparation: The positive electrode material of the present invention, polyvinylidene fluoride (PVDF) as a binder, and conductive carbon black (SP) were thoroughly mixed in a weight ratio of 7:2:1, stirred to form a uniform slurry, which was then applied to an aluminum foil current collector, dried, and pressed into a tab. The pressed positive electrode sheet is punched, weighed, and sintered, and then the battery is assembled in a vacuum glove box. First, the bottom of the button battery is placed on top of the bottom of the can, and then foamed nickel (2.5 mm) and a negative electrode metallic sodium sheet (manufacturer: Shenzhen Youken Technology Co., Ltd.) are placed on top of the can bottom. In an environment with a relative humidity of less than 1.5%, 0.5 g of electrolyte, a mixed solvent of ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) in a mass ratio of 1:1:1, is poured into the battery. The electrolyte is a 1 mol / L sodium hexafluorophosphate solution. A separator and a positive electrode sheet are placed, and the button battery case lid is placed on top and sealed. The button battery model number is CR2430.

[0089] The present invention will now be described in more detail by way of specific embodiments with reference to the accompanying drawings. Example 1

[0090] Sodium carbonate, manganese carbonate, nickel carbonate, ferric oxide, zinc oxide, calcium oxide, and copper oxide were weighed out in the stoichiometric ratio of Na:Mn:Ni:Fe:Zn:Ca:Cu = 0.82:0.32:0.24:0.31:0.08:0.03:0.02 and then added to an ultra-high-speed multi-function compounder and mixed for 30 minutes at 4000 r / min. The homogeneously mixed materials were heated from room temperature to 950°C at a rate of 5°C / min in an air atmosphere, held at this temperature for 12 hours, then naturally cooled. The mixture was then ground in an ultra-fine disc mill with a disc mill gap of 1.0 mm and a speed of 1800 r / min to obtain a semi-finished product. The molecular formula of the semi-finished product was obtained using ICP testing, and the amount of material in the semi-finished product was calculated. Furthermore, the above semi-finished product and magnesium source (elemental magnesium) were mixed in a molar ratio of 1:0.04, and magnesium oxide was weighed and placed in a ball mill. The ball milling was carried out at 40 Hz for 10 minutes. The uniformly mixed material was heated from room temperature to 550°C at a heating rate of 8°C / min in an air atmosphere, kept at the same temperature for 3 hours, and then cooled naturally. The material was then pulverized and sieved using an ultra-fine stone disc mill with a disc mill gap of 1.0 mm and a rotation speed of 1800 r / min to obtain the material with the molecular formula Na. 0.81 Ni 0.23 Mn 0.31 Zn 0.077 Fe 0.297 Ca 0.029 Cu 0.019 Mg 0.038 The positive electrode material for O2 sodium ion batteries was obtained.

[0091] An XRD test was carried out on the sodium ion battery positive electrode material of this example. As shown in FIG. 1, the results are as follows: the full width at half maximum (FWHM) at a diffraction angle 2θ of 16.49° is 0.120°, and the crystal plane spacing is 5.372 Å. It had five diffraction peaks between the diffraction angle 2θ values ​​of 30° and 40°, and the full width at half maximum FWHM of the diffraction peak at 2θ of 32.27° was 0.110°, and the crystal plane spacing was 2.771 Å, the full width at half maximum FWHM of the diffraction peak at 2θ of 33.38° was 0.127°, and the crystal plane spacing was 2.682 Å, the full width at half maximum FWHM of the diffraction peak at 2θ of 34.44° was 0.16°, and the crystal plane spacing was 2.602 Å, the full width at half maximum FWHM of the diffraction peak at 2θ of 35.24° was 0.109°, and the crystal plane spacing was 2.544 Å, and the full width at half maximum FWHM of the diffraction peak at 2θ of 36.58° was 0.100°, and the crystal plane spacing was 2.454 Å. There were two diffraction peaks between 41° and 46° in the 2θ range, with the strongest peak at 41.59° having a full width at half maximum (FWHM) of 0.089° and a crystal plane spacing of 2.169 Å. The diffraction peak at 2θ of 45.04° had a full width at half maximum (FWHM) of 0.082° and a crystal plane spacing of 2.011 Å. The ratio of the intensity of the (003) diffraction peak at 16.49° in the 2θ range to the intensity of the (104) diffraction peak at 41.59° in the 2θ range was 0.57.

[0092] The free sodium content of the positive electrode material is 2.12% and the BET specific surface area is 0.91m 2 / g, particle size D50 is 8.7 μm, tap density TD is 1.68 g / cm 3 The positive electrode material of this example was fabricated into a button battery, and capacity and cycle tests were performed. Figure 2 is a 0.5C cycle graph of the positive electrode material of this example under the conditions of 4.0 to 2.0V. Example 2

[0093] Sodium carbonate, manganese carbonate, nickel oxide, ferrous oxalate, zinc oxide, titanium dioxide, and yttrium trioxide were weighed out in the stoichiometric molar ratio of Na:Mn:Ni:Fe:Zn:Ti:Y = 0.76:0.32:0.27:0.297:0.083:0.02:0.01. Then, the materials were added to an ultra-high-speed multi-function compounder and mixed at 10,000 r / min for 15 minutes to achieve uniform mixing. The uniformly mixed materials were heated to 945°C at a rate of 3°C / min in an air atmosphere, held at this temperature for 16 hours, then naturally cooled. The materials were then ground in an ultra-fine disc mill with a disc mill gap of 1.5 mm and a rotation speed of 2,000 r / min to obtain semi-finished products. The molecular formulas of the semi-finished products were obtained using ICP testing, and the amounts of the components were calculated. Furthermore, the above semi-finished product and aluminum source (aluminum element) were mixed in a molar ratio of 1:0.015, and aluminum oxide was weighed and placed in a ball mill. The ball mill frequency was 40Hz and the ball milling was carried out for 15 minutes. The uniformly mixed material was heated from room temperature to 780°C at a heating rate of 7°C / min in an air atmosphere, kept at the same temperature for 4 hours, and then cooled naturally. The material was then pulverized and sieved using an ultra-fine stone disc mill with a disc mill gap of 1.0mm and a rotation speed of 1800r / min to obtain a powder with the molecular formula Na. 0.76 Ni 0.27 Mn 0.32 Zn 0.083 Fe 0.282 Ti 0.02 Y 0.01 Al 0.015 The positive electrode material for O2 sodium ion batteries was obtained.

[0094] An XRD test was performed on the sodium-ion battery positive electrode material of this example, and the results were as follows, as shown in Figure 3. The full width at half maximum (FWHM) at a diffraction angle 2θ of 16.47° was 0.109°, and the crystal plane spacing was 5.376 Å. There were four diffraction peaks between the diffraction angle 2θ of 30° and 40°. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 33.38° was 0.118°, and the crystal plane spacing was 2.681 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 34.42° was 0.120°, and the crystal plane spacing was 2.603 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 35.16° was 0.092°, and the crystal plane spacing was 2.550 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 36.51° was 0.086°, and the crystal plane spacing was 2.459 Å. There were two diffraction peaks between 41° and 46° in the 2θ range, with the strongest peak at 41.53°, having a full width at half maximum (FWHM) of 0.079° and a crystal plane spacing of 2.173 Å. The diffraction peak at 2θ of 44.99° had a full width at half maximum (FWHM) of 0.082° and a crystal plane spacing of 2.012 Å. The ratio of the intensity of the (003) diffraction peak at 16.47° in the 2θ range to the intensity of the (104) diffraction peak at 41.53° in the 2θ range was 0.54.

[0095] The free sodium content of the positive electrode material is 1.88% and the BET specific surface area is 0.74m 2 / g, particle size D50 is 10.4 μm, tap density TD is 2.12 g / cm 3 The positive electrode material of this example was fabricated into a button battery, and capacity and cycle tests were performed. Figure 4 is a cycle graph of the positive electrode material of this example at 0.5C under conditions of 4.0 to 2.0V. Example 3

[0096] Sodium carbonate, manganese oxide, nickel oxide, ferric oxide, zinc oxide, and titanium dioxide were weighed out in the stoichiometric molar ratio of Na:Mn:Ni:Fe:Zn:Ti = 0.83:0.32:0.23:0.296:0.098:0.056. Then, the materials were added to an ultra-high-speed multi-function compounder and mixed at 14,000 r / min for 25 minutes to achieve uniform mixing. The uniformly mixed materials were heated to 974°C at a rate of 4°C / min in an air atmosphere, held at this temperature for 10 hours, then naturally cooled. The materials were then ground in an ultra-fine disc mill with a disc mill gap of 0.6 mm and a rotation speed of 2,000 r / min to obtain semi-finished products. The molecular formulas of the semi-finished products were obtained using ICP testing, and the amounts of the components were calculated. Furthermore, the above semi-finished product and titanium source were mixed in a molar ratio of 1:0.04, and titanium oxide was weighed and placed in a ball mill. The ball mill frequency was 45Hz and the ball milling was carried out for 8 minutes. The uniformly mixed material was heated from room temperature to 480°C at a heating rate of 9°C / min in an air atmosphere, kept at the same temperature for 6 hours, and then cooled naturally. The material was then pulverized and sieved using an ultra-fine stone disc mill with a disc mill gap of 1.0mm and a rotation speed of 1800r / min to obtain the material with the molecular formula Na. 0.83 Ni 0.22 Mn 0.32 Ti 0.09 Zn 0.098 Fe 0.272 O2 cathode material was obtained.

[0097] An XRD test was performed on the sodium-ion battery positive electrode material of this example, and the results were as follows, as shown in Figure 5. The full width at half maximum (FWHM) at a diffraction angle 2θ of 16.33° was 0.111°, and the crystal plane spacing was 5.423 Å. There were three diffraction peaks between diffraction angles 2θ of 30° and 40°. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 33.10° was 0.104°, and the crystal plane spacing was 2.701 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 35.40° was 0.214°, and the crystal plane spacing was 2.533 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 36.72° was 0.181°, and the crystal plane spacing was 2.445 Å. There were two diffraction peaks between 41° and 46° in the 2θ range, with the strongest peak at 41.64°, having a full width at half maximum (FWHM) of 0.079° and a crystal plane spacing of 2.167 Å. The diffraction peak at 45.04° in 2θ had a full width at half maximum (FWHM) of 0.080° and a crystal plane spacing of 2.011 Å. The ratio of the intensity of the (003) diffraction peak at 16.33° in 2θ to the intensity of the (104) diffraction peak at 41.64° in 2θ was 0.65.

[0098] The free sodium content of the positive electrode material is 1.98% and the BET specific surface area is 0.67m 2 / g, particle size D50 is 5.1 μm, tap density TD is 1.75 g / cm 3 The positive electrode material of this example was fabricated into a button battery, and capacity and cycle tests were performed. Figure 6 is a cycle graph of the positive electrode material of this example at 0.5C under conditions of 4.0 to 2.0V. Example 4

[0099] Sodium nitrate, manganese trioxide, nickel oxalate, ferrous oxalate, titanium dioxide, and aluminum trioxide were weighed out in the stoichiometric molar ratio of Na:Mn:Ni:Fe:Ti:Al = 0.79:0.19:0.3:0.33:0.17:0.01 and then added to an ultra-high-speed multi-function compounder at 17,000 r / min for 45 minutes to achieve uniform mixing. The uniformly mixed materials were heated to 890°C at a rate of 5°C / min in an air / oxygen atmosphere (7:3 by volume), maintained at this temperature for 18 hours, and then naturally cooled. The semi-finished products were then milled using an ultra-fine disc mill with a disc mill gap of 0.8 mm and a rotation speed of 1,800 r / min. The molecular formulas of the semi-finished products were obtained using ICP testing, and the amounts of the components were calculated. Furthermore, the above semi-finished product and the boron source (B element) were mixed in a molar ratio of 1:0.02, and boron oxide was weighed and placed in a ball mill. The ball milling was carried out at a frequency of 55 Hz for 10 minutes. The uniformly mixed material was heated from room temperature to 280°C at a rate of 6°C / min in an air atmosphere, kept at the same temperature for 7 hours, then naturally cooled, and sieved to obtain a material with the molecular formula Na 0.79 Ni 0.3 Fe 0.31 Mn 0.19 Ti 0.17 Al 0.01 B 0.02 O2 cathode material was obtained.

[0100] An XRD test was performed on the sodium-ion battery positive electrode material of this example, and the results were as follows, as shown in Figure 7. The full width at half maximum (FWHM) at a diffraction angle 2θ of 16.32° was 0.123°, and the crystal plane spacing was 5.427 Å. There were four diffraction peaks between diffraction angles 2θ of 30° and 40°. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 32.26° was 0.170°, and the crystal plane spacing was 2.772 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 33.07° was 0.111°, and the crystal plane spacing was 2.706 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 35.42° was 0.092°, and the crystal plane spacing was 2.533 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 36.73° was 0.095°, and the crystal plane spacing was 2.445 Å. There were two diffraction peaks between 41° and 46° in the 2θ range, with the strongest peak at 41.642°, having a full width at half maximum (FWHM) of 0.09° and a crystal plane spacing of 2.167 Å. The diffraction peak at 45.03° in 2θ had a full width at half maximum (FWHM) of 0.08° and a crystal plane spacing of 2.011 Å. The ratio of the intensity of the (003) diffraction peak at 16.32° in 2θ to the intensity of the (104) diffraction peak at 41.642° in 2θ was 0.67.

[0101] The free sodium content of the positive electrode material is 2.05% and the BET specific surface area is 0.59m 2 / g, particle size D50 is 4.9 μm, tap density TD is 1.95 g / cm 3 The positive electrode material of this example was fabricated into a button battery, and capacity and cycle tests were performed. Figure 8 is a cycle graph of the positive electrode material of this example at 0.5C under conditions of 4.0 to 2.0V. Example 5

[0102] Sodium carbonate, manganese oxalate, nickel oxalate, ferrous oxalate, titanium dioxide, and zinc oxide were weighed out in the stoichiometric molar ratio of Na:Mn:Ni:Fe:Ti:Zn = 0.81:0.31:0.18:0.3:0.14:0.07. Then, the materials were added to an ultra-high-speed multi-function compounder and mixed at 25,000 r / min for 30 minutes to achieve uniform mixing. The uniformly mixed materials were heated to 910°C at a rate of 4°C / min in an air / oxygen atmosphere (air / oxygen volume ratio 9:1), maintained at this temperature for 40 hours, and then naturally cooled. The materials were then ground in an ultra-fine disc mill with a disc mill gap of 0.4 mm and a rotation speed of 2,200 r / min to obtain semi-finished products. The molecular formulas of the semi-finished products were obtained using ICP testing, and the amounts of the components were calculated. Furthermore, the above semi-finished product and aluminum source (aluminum element) were mixed in a molar ratio of 1:0.03, and aluminum oxide was weighed and placed in a ball mill. The ball mill frequency was 40Hz and the ball milling was carried out for 30 minutes. The uniformly mixed material was heated from room temperature to 750°C at a heating rate of 6°C / min in an air atmosphere, kept at the same temperature for 8 hours, and then cooled naturally. The material was then pulverized and sieved using an ultra-fine stone disc mill with a disc mill gap of 1.2mm and a rotation speed of 2200r / min to obtain a powder with the molecular formula Na. 0.8 Ni 0.17 Mn 0.3 Ti 0.13 Fe 0.3 Zn 0.07 Al 0.03 O2 cathode material was obtained.

[0103] FIG. 9 shows the XRD chromatogram of the positive electrode material of this example. As can be seen from FIG. 9, there was a semi-intense peak at a diffraction angle 2θ value of 16.54°, with a full width at half maximum (FWHM) of 0.109° and a crystal plane spacing of 5.353 Å. It has four diffraction peaks between the diffraction angle 2θ values ​​of 30° and 40°, and the full width at half maximum (FWHM) of the diffraction peak at 2θ of 33.37° is 0.160°, and the crystal plane spacing is 2.675 Å; the full width at half maximum (FWHM) of the diffraction peak at 2θ of 35.21° is 0.184°, and the crystal plane spacing is 2.547 Å; the full width at half maximum (FWHM) of the diffraction peak at 2θ of 36.555° is 0.148°, and the crystal plane spacing is 2.461 Å; and the full width at half maximum (FWHM) of the diffraction peak at 2θ of 37.21° is 0.103°, and the crystal plane spacing is 2.415 Å. There were two diffraction peaks between 41° and 46° in the 2θ range, with the strongest peak at 41.58° in the 2θ range, with a full width at half maximum (FWHM) of 0.125° and a crystal plane spacing of 2.171 Å. The diffraction peak at 45.04° in the 2θ range had a full width at half maximum (FWHM) of 0.111° and a crystal plane spacing of 2.015 Å. The ratio of the intensity of the (003) diffraction peak at 16.54° in the 2θ range to the intensity of the (104) diffraction peak at 41.58° in the 2θ range was 0.95.

[0104] The free sodium content of the positive electrode material is 2.03% and the specific surface area BET is 0.86m 2 / g, particle size D50 is 3.9 μm, tap density TD is 1.82 g / cm 3 The positive electrode material of this example was fabricated into a button battery, and capacity and cycle tests were performed. Figure 10 is a cycle graph of the positive electrode material of this example at 0.5C under conditions of 4.0 to 2.0V. Example 6

[0105] Sodium carbonate, manganese oxalate, nickel oxalate, ferrous oxalate, titanium dioxide, and zinc oxide were weighed out in the stoichiometric molar ratio of Na:Mn:Ni:Fe:Ti:Zn = 0.81:0.31:0.18:0.3:0.14:0.07. Then, the materials were mixed in proportions in an ultra-high-speed multi-function compounder at 25,000 r / min for 30 minutes to achieve uniform mixing. The uniformly mixed materials were heated to 910°C at a rate of 4°C / min in an air atmosphere, maintained at this temperature for 40 hours, and then naturally cooled. The materials were then ground in an ultra-fine disc mill with a disc mill gap of 0.4 mm and a rotation speed of 2,200 r / min to obtain semi-finished products. The molecular formulas of the semi-finished products were obtained using ICP testing, and the amounts of the components were calculated. Furthermore, the above semi-finished product and aluminum source (aluminum element) were mixed in a molar ratio of 1:0.06, and aluminum oxide was weighed and placed in a ball mill. The ball mill frequency was 40Hz and the ball milling was carried out for 30 minutes. The uniformly mixed material was heated from room temperature to 750°C at a heating rate of 6°C / min in an air atmosphere, kept at the same temperature for 8 hours, and then cooled naturally. The material was then pulverized and sieved using an ultra-fine stone disc mill with a disc mill gap of 1.2mm and a rotation speed of 2500r / min to obtain a powder with the molecular formula Na. 0.81 Ni 0.165 Mn 0.295 Ti 0.13 Fe 0.29 Zn 0.06 Al 0.06 O2 cathode material was obtained.

[0106] FIG. 11 shows the XRD chromatogram of the positive electrode material of this example. As can be seen from FIG. 11, there was a semi-intense peak at a diffraction angle 2θ value of 16.55°, with a full width at half maximum (FWHM) of 0.111° and a crystal plane spacing of 5.351 Å. It has four diffraction peaks between the diffraction angle 2θ values ​​of 30° and 40°, and the full width at half maximum (FWHM) of the diffraction peak at 2θ of 33.33° is 0.162°, and the crystal plane spacing is 2.672 Å; the full width at half maximum (FWHM) of the diffraction peak at 2θ of 35.22° is 0.181°, and the crystal plane spacing is 2.542 Å; the full width at half maximum (FWHM) of the diffraction peak at 2θ of 36.551° is 0.146°, and the crystal plane spacing is 2.458 Å; and the full width at half maximum (FWHM) of the diffraction peak at 2θ of 37.23° is 0.105°, and the crystal plane spacing is 2.412 Å. There are two diffraction peaks between 41° and 46° in the 2θ range, with the strongest peak at 41.56° in the 2θ range, with a full width at half maximum (FWHM) of 0.122° and a crystal plane spacing of 2.172 Å. The diffraction peak at 45.06° in the 2θ range has a full width at half maximum (FWHM) of 0.109° and a crystal plane spacing of 2.013 Å. The ratio of the intensity of the (003) diffraction peak at 16.55° in the 2θ range to the intensity of the (104) diffraction peak at 41.56° in the 2θ range was 0.93.

[0107] The free sodium content of the positive electrode material is 1.94% and the BET specific surface area is 0.88m 2 / g, particle size D50 is 4.3 μm, tap density TD is 1.87 g / cm 3 The positive electrode material of this example was fabricated into a button battery, and capacity and cycle tests were performed. Figure 12 is a cycle graph of the positive electrode material of this example at 0.5C under conditions of 4.0 to 2.0V. (Comparative Example 1)

[0108] Sodium nitrate, manganese trioxide, nickel oxalate, ferrous oxalate, titanium dioxide, aluminum trioxide, and boron oxide were weighed out in the stoichiometric molar ratio of Na:Mn:Ni:Fe:Ti:Al:B = 0.79:0.19:0.3:0.31:0.17:0.01:0.02. Then, the materials were added to an ultra-high-speed multi-function compounder and mixed at 17,000 r / min for 45 minutes to achieve uniform mixing. The uniformly mixed materials were heated to 890°C at a rate of 5°C / min in an air / oxygen atmosphere (air / oxygen volume ratio 7:3), maintained at this temperature for 18 hours, and then naturally cooled. The materials were then pulverized and sieved using an ultra-fine stone disc mill with a disc mill gap of 0.8 mm and a rotation speed of 1,800 r / min to obtain a powder with the molecular formula Na. 0.79 N i0.3 Fe 0.31 Mn 0.19 Ti 0.17 Al 0.01 B 0.02 O2 cathode material was obtained.

[0109] An XRD test was performed on the sodium-ion battery positive electrode material of this example, and the results were as follows, as shown in Figure 13. The full width at half maximum (FWHM) at a diffraction angle 2θ of 16.30° was 0.113°, and the crystal plane spacing was 5.445 Å. There were four diffraction peaks between diffraction angles 2θ of 30° and 40°. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 32.21° was 0.150°, and the crystal plane spacing was 2.775 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 33.04° was 0.106°, and the crystal plane spacing was 2.716 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 35.32° was 0.087°, and the crystal plane spacing was 2.543 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 36.63° was 0.090°, and the crystal plane spacing was 2.455 Å. There were two diffraction peaks between 41° and 46° in the 2θ range, with the strongest peak at 41.611° having a full width at half maximum (FWHM) of 0.085° and a crystal plane spacing of 2.174 Å. The diffraction peak at 2θ of 45.01° had a full width at half maximum (FWHM) of 0.08° and a crystal plane spacing of 2.024 Å. The ratio of the intensity of the (003) diffraction peak at 16.30° in the 2θ range to the intensity of the (104) diffraction peak at 41.611° in the 2θ range was 0.64.

[0110] The free sodium content of the positive electrode material is 2.45% and the BET specific surface area is 0.51m 2 / g, particle size D50 is 5.5 μm, tap density TD is 2.11 g / cm 3 The positive electrode material of this comparative example was manufactured into a button battery, and capacity and cycle tests were performed. Fig. 14 is a cycle graph of the positive electrode material of this comparative example at 0.5C under conditions of 4.0 to 2.0V. (Comparative Example 2)

[0111] Sodium carbonate, manganese carbonate, nickel carbonate, and ferrous oxalate were weighed out in the corresponding amounts according to the stoichiometric molar ratio of Na:Mn:Ni:Fe=0.76:0.35:0.30:0.35, and then added to an ultra-high speed multi-functional compounder in proportion, and mixed at a rotation speed of 20,000 r / min for 15 minutes to achieve uniform mixing. The uniformly mixed material was heated to 905°C at a heating rate of 3°C / min in an air atmosphere, kept at a constant temperature for 18 hours, then naturally cooled, and then pulverized using an ultra-fine disc mill with a disc mill gap of 1.5mm and a rotation speed of 2000r / min to obtain a semi-finished product. The semi-finished product and aluminum source (aluminum element) were mixed in a molar ratio of 1:0.015, and aluminum oxide was weighed and placed in a ball mill. The ball milling was carried out at a ball mill frequency of 40Hz for 15 minutes. The uniformly mixed material was heated from room temperature to 780°C at a heating rate of 7°C / min in an air atmosphere, kept at a constant temperature for 4 hours, then naturally cooled, and then pulverized using an ultra-fine stone disc mill with a disc mill gap of 1.0mm and a rotation speed of 1800r / min. The mill was sieved to obtain a powder with the molecular formula Na 0.76 Ni 0.30 Mn 0.343 Fe 0.342 Al 0.015 The positive electrode material for O2 sodium ion batteries was obtained.

[0112] An XRD test was performed on the sodium-ion battery positive electrode material of this example, and the results were as follows, as shown in Figure 15. The full width at half maximum (FWHM) at a diffraction angle 2θ of 16.46° was 0.163°, and the crystal plane spacing was 5.378 Å. There were four diffraction peaks between diffraction angles 2θ of 30° and 40°. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 33.34° was 0.161°, and the crystal plane spacing was 2.682 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 35.23° was 0.136°, and the crystal plane spacing was 2.542 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 36.58° was 0.137°, and the crystal plane spacing was 2.451 Å. The full width at half maximum (FWHM) of the diffraction peak at 2θ of 37.16° was 0.122°, and the crystal plane spacing was 2.419 Å. There were three diffraction peaks between 41° and 46° (2θ), with the strongest peak at 41.61° (2θ) having a full width at half maximum (FWHM) of 0.127° and a crystal plane spacing of 2.167 Å. The peak at 43.21° (2θ) had a full width at half maximum (FWHM) of 0.131° and a crystal plane spacing of 2.091 Å. The peak at 45.01° (2θ) had a full width at half maximum (FWHM) of 0.122° and a crystal plane spacing of 2.012 Å. The ratio of the intensity of the (003) diffraction peak at 16.46° (2θ) to the intensity of the (104) diffraction peak at 41.61° (2θ) was 0.57.

[0113] The free sodium content of the positive electrode material is 14.5% and the BET specific surface area is 0.57m 2 / g, particle size D50 is 11.8 μm, tap density TD is 1.87 g / cm 3 The positive electrode material of this comparative example was manufactured into a button battery, and capacity and cycle tests were performed. Fig. 16 is a cycle graph of the positive electrode material of this comparative example at 0.5C under conditions of 4.0 to 2.0V.

[0114] The performance of the positive electrode materials obtained in the examples and comparative examples is summarized in Table 2 below.

[0115] [Table 2]

[0116] As can be seen from the above table, the positive electrode material of Comparative Example 1, which does not contain coating element B, has a capacity retention rate after 50 cycles of 73.5%, which is much lower than the cycle retention rates of Examples 1 to 6. The positive electrode material of Comparative Example 2, which does not contain doping element A, has a capacity retention rate after 50 cycles of 86.3%, which is much lower than the cycle retention rates of Examples 1 to 6.

[0117] The applicant asserts that the above is merely a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto, and that it should be clear to those skilled in the art that any modifications or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are included in the protection scope and disclosure scope of the present invention.

[0118] (Addendum) (Appendix 1) A sodium ion battery positive electrode material having a coating structure, The general chemical formula of the positive electrode material is Na 1+a Ni x Mn y Fe z A m B n O2, where -0.35≦a≦0.20 and 0.08 <x≦0.5であり、0.05<y≦0.48であり、0.03<z<0.4であり、0.03<m<0.24であり、0.001<n<0.06であり、x+y+z+m+n=1であり、 wherein A is a modifying element, and the A element includes one or more of Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P and Cu elements; Here, the B element is an element in the coating layer, and the B element includes one or more of Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P and Cu elements. A sodium ion battery positive electrode material having a coating structure characterized by the above-mentioned.

[0119] (Appendix 2) The general chemical formula of the positive electrode material is Na 1+a Ni x Mn y Fe z A m B n O2, where -0.35≦a≦0.20, 0.1≦x≦0.3, 0.1≦y≦0.4, 0.2≦z≦0.4, 0.05≦m≦0.2, and 0.01 <n≦0.05であり、x+y+z+m+n=1であり、 Preferably, A includes one or more of Ti, Zn, Al, Zr, Y, Ca, Li, W, Ce, Mo, Ba, Mg, Ta, Nb, Sc, Sr, B, F, P and Cu elements, More preferably, A includes one or more of Ti, Zn, Al, Y, Ca, Zr, Li, Mg, Mn, Sr, F, B, and Cu, and / or the B contains one or more of Ti, Co, Mn, Al, Zr, Y, Li, Mg, B, F, P and Cu elements; More preferably, the B is one or a combination of two or more selected from the group consisting of Mg, Zr, P, F, Al, Mg, Ti and B elements. 10. The sodium-ion battery cathode material of claim 1.

[0120] (Appendix 3) A includes Zn and M, where the content of Zn is represented by b, and the total content of Zn and M is m; The general chemical formula of the positive electrode material is Na 1+a Ni x Mn y Fe z Zn b M m-b B nIt is O₂, -0.35 ≦ a ≦ 0.20, 0.08 < x ≦ 0.5, 0.05 < y ≦ 0.48, 0.03 < z < 0.4, 0.03 < m < 0.24, 0.001 < n < 0.06, x + y + z + m + n = 1, 0 < b ≦ 0.12, and the M element is one or more selected from the group consisting of Ti, Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, and Cu elements. Preferably, the M element is one or more selected from the group consisting of Mn, Ti, Al, Y, Ca, Mg, F, P, B, and Cu. The sodium ion battery cathode material according to Supplementary Note 1.

[0121] (Supplementary Note 4) The A contains Ti element and N element. Here, the content of the Ti element is represented by c, and the total content of the Ti element and the N element is m. The chemical general formula of the cathode material is Na 1+a Ni x Mn y Fe z Ti c N m-c B n It is O₂, -0.35 ≦ a ≦ 0.20, 0.08 < x ≦ 0.5, 0.05 < y ≦ 0.48, 0.03 < z < 0.4, 0.03 < m < 0.24, 0.001 < n < 0.06, x + y + z + m + n = 1, 0 < c < 0.24, and the N is one or more selected from the group consisting of Ti, Zn, Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, and Cu elements. Preferably, the N is one or more selected from the group consisting of Mn, Mg, F, Li, Zn, Al, Y, Ca, B, and Cu. The sodium ion battery cathode material according to Supplementary Note 1.

[0122] (Supplementary Note 5) The A element contains Zn element, Ti element and X element. Here, the content of Zn element is represented by d, the content of Ti element is represented by e, and the total content of Zn element, Ti element and X element is m. The chemical general formula of the positive electrode material is Na 1+a Ni x Mn y Fe z Zn d Ti e X m-d-e B n O2, where -0.35 ≦ a ≦ 0.20, 0.08 < x ≦ 0.5, 0.05 < y ≦ 0.48, 0.03 < z < 0.4, 0.03 < m < 0.24, 0.001 < n < 0.06, x + y + z + m + n = 1, 0 < d ≦ 0.1, 0 < e < 0.24. The X is one or a combination of two or more selected from the group consisting of Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P and Cu elements. Preferably, the X is one or a combination of two or more selected from the group consisting of Co, Mn, Al, Zr, Y, Ca, Li, W, Ba, Mg, Nb, B, F, P and Cu elements. The sodium ion battery positive electrode material according to Supplementary Note 1.

[0123] (Supplementary Note 6) In the X-ray diffraction spectrum of the sodium ion battery positive electrode material powder, there is any one of the characteristics consisting of the following six characteristics. (1) It has at least two diffraction peaks between diffraction angle 2θ values of 41° to 46°. Preferably, the diffraction angle 2θ values of these two diffraction peaks are respectively near 41° and near 45°. More preferably, the full width at half maximum FWHM of these two diffraction peaks is 0.07° to 0.29°, and / or the interplanar spacing of the two diffraction peaks between diffraction angle 2θ values of 41° to 46° is 1.85 Å to 2.75 Å. [[ID=--32]](2) The full width at half maximum FWHM of the diffraction peak near 41° of the diffraction angle 2θ value is 0.07° to 0.17°, and the full width at half maximum FWHM of the diffraction peak near 45° of the diffraction angle 2θ value is 0.07° to 0.23°. (3) At least three diffraction peaks between the diffraction angle 2θ values ​​of 30° and 40°; Preferably, the diffraction angle 2θ values ​​are around 33°, around 35°, and around 36°, respectively; (4) It has four diffraction peaks between the diffraction angle 2θ values ​​of 30° and 40°, and the diffraction angle 2θ values ​​are respectively around 32°, 33°, 35°, and 36°, or the diffraction angle 2θ values ​​are respectively around 33°, around 35°, around 36°, and around 37°; or the diffraction angle 2θ values ​​are respectively around 33°, around 34°, around 35°, and around 36°; (5) has five diffraction peaks between 30° and 40° in diffraction angle 2θ values, and the diffraction angle 2θ values ​​are respectively around 32°, 33°, 34°, 35°, and 36°; and (6) the ratio of the peak intensity of the (003) diffraction peak at a diffraction angle 2θ of about 16° to the peak intensity of the (104) diffraction peak at a diffraction angle 2θ of about 41° is 0.4 to 1.4; Preferably, the ratio to this peak intensity is 0.45 to 1.2. 10. The sodium-ion battery cathode material of claim 1.

[0124] (Appendix 7) The specific surface area of ​​the sodium ion battery positive electrode material is 0.2 to 1.2 m 2 / g, and preferably, the specific surface area of ​​the sodium ion battery positive electrode material is 0.4 to 1.0 m 2 / g, and / or the particle size D50 of the sodium ion battery positive electrode material is 2 to 18 μm, preferably the particle size D50 of the sodium ion battery positive electrode material is 3 to 15 μm, more preferably the particle size D50 of the sodium ion battery positive electrode material is 5 to 11 μm; and / or the tap density of the sodium ion battery positive electrode material is 1.2 to 2.9 g / cm 3 and preferably, the tap density of the sodium ion battery positive electrode material is 1.2 to 2.6 g / cm 3 and and / or the powder X-ray diffraction spectrum of the sodium ion battery positive electrode material shows that it has an α-NaFeO2 type layered structure; and / or the total free sodium content of the sodium-ion battery positive electrode material is 2.3% or less, preferably the total free sodium content of the sodium-ion battery positive electrode material is 2.0% or less; 10. The sodium-ion battery cathode material of claim 1.

[0125] (Appendix 8) a step (1) of uniformly mixing a sodium source, a nickel source, a manganese source, an iron source, and an A source, followed by a first sintering, cooling, and pulverizing to obtain a semi-finished product; (2) uniformly mixing the semi-finished product and the B source, followed by a second sintering, cooling, and pulverizing to obtain a sodium ion positive electrode material; 8. A method for producing a sodium ion battery positive electrode material according to any one of appendices 1 to 7.

[0126] (Appendix 9) In step (1), a sodium source, a nickel source, a manganese source, an iron source, and an A source are mixed by a solid-phase mixing method; And / or, in step (2), the semi-finished product and the B source are mixed by a solid-phase mixing method, preferably a ball mill mixing method. 9. A method for producing the sodium ion battery positive electrode material according to claim 8.

[0127] (Appendix 10) In step (1), the conditions for the first sintering are as follows: the temperature rise rate is 3 to 5°C / min, the temperature is 780 to 980°C, and the time is 8 to 40 hours; and / or, in step (2), the conditions for the second sintering are as follows: the temperature rise rate is 6 to 9°C / min, the temperature is 180 to 850°C, and the time is 2 to 10 hours; preferably, the atmosphere for the first sintering is an oxygen-containing gas, more preferably air, oxygen, or a mixture thereof; and / or the atmosphere of the second sintering is an oxygen-containing gas, more preferably air, oxygen or a mixture thereof; 9. A method for producing the sodium ion battery positive electrode material according to claim 8.

[0128] (Appendix 11) The Na source includes one or more of sodium hydroxide, sodium carbonate, sodium nitrate, sodium oxalate, sodium chloride, sodium fluoride, and sodium acetate. 9. A method for producing the sodium ion battery positive electrode material according to claim 8.

[0129] (Appendix 12) the A source is an oxide 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, a salt thereof, or an organic substance thereof; Preferably, the A source is a carbonate, oxalate, nitrate or oxide 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 elements; More preferably, the A source comprises one or more of zinc oxide, titanium dioxide, calcium oxide, copper oxide, aluminum oxide, yttrium trioxide, boron trioxide, barium oxide, niobium oxide, magnesium oxide, and zirconium oxide. 9. A method for producing the sodium ion battery positive electrode material according to claim 8.

[0130] (Appendix 13) the B source is one or more oxides, salts or organic substances thereof selected from the group consisting of Ti, Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P and Cu elements; Preferably, the B source is a carbonate, oxalate, nitrate, or oxide of one or more elements selected from the group consisting of Ti, Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, and Cu elements; More preferably, the B source comprises one or more of magnesium oxide, aluminum oxide, titanium oxide, magnesium acetate, aluminum acetate, aluminum nitrate, boric acid, and boron oxide. 9. A method for producing the sodium ion battery positive electrode material according to claim 8.

[0131] (Appendix 14) A sodium ion battery positive electrode, comprising the sodium ion battery positive electrode material according to any one of appendices 1 to 7 as a positive electrode active material; A sodium ion battery positive electrode characterized by:

[0132] (Appendix 15) A sodium ion battery comprising the positive electrode of claim 14, a negative electrode, and an electrolyte containing a sodium salt. A sodium-ion battery characterized by:

[0133] (Appendix 16) Use of the sodium-ion battery of claim 15 as a power source in a solar, electric, energy storage system or mobile storage device or low-end electric vehicle; Preferably for use in distributed energy storage, centralized energy storage or low end power battery energy storage devices.

[0134] (Appendix 17) A power system, an energy storage system, or a mobile storage device, manufactured by the sodium-ion battery according to claim 15. 1. A power system, energy storage system or mobile storage device comprising:

Claims

[Claim 1] A sodium ion battery positive electrode material having a coating structure, The general chemical formula of the positive electrode material is Na １＋ａ Ni ｘ Mn ｙ Fe ｚ Zn ｂ M ｍ－ｂ B ｎ O ２ -0.35≦a≦0.20, 0.22≦x≦0.3, 0.1≦y≦0.4, 0.2≦z≦0.4, 0.05≦m≦0.2, 0.01<n≦0.05, x+y+z+m+n=1, and 0<b≦0.12; Zn element and M element are modifying elements, and the M element is one or a combination of two or more selected from the group consisting of Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B (boron), F, P, and Cu elements; Here, the B element is an element in the coating layer, and the B element is one or a combination of two or more elements selected from the group consisting of Mg, Zr, P, F, Al, Ti, and B (boron). A sodium ion battery positive electrode material having a coating structure characterized by the above-mentioned.

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