Nitrogen-containing positive electrode material and preparation method thereof, positive electrode, sodium ion battery and preparation method of sodium ion battery

Abstract

The invention discloses a nitrogen-containing positive electrode material and a preparation method thereof, and a positive electrode and a sodium ion battery adopting the nitrogen-containing positive electrode material and a preparation method thereof. The nitrogen-containing positive electrode material disclosed by the invention has the composition shown as a formula I: Nax (MaNb) Ny (formula I), wherein M is selected from transition metal elements; n is nitrogen; n has two existence forms; wherein 0.5 < = x < = 1.5, 0.1 < = a < = 0.9, 0.1 < = b < = 0.9, and 0.5 < = y < = 1.5. By optimizing the microstructure and conductivity of the material, the performance of the material under the condition of high-rate discharge is improved, and the requirements of quick charge and high-power discharge are met.

Description

Technical Field

[0001] The present invention relates to the field of new energy, especially the field of sodium-ion batteries, and particularly relates to a nitrogen-containing cathode material and a preparation method thereof, a cathode using the cathode material, a sodium-ion battery, and a preparation method thereof. Background Art

[0002] A sodium-ion battery is a secondary battery. As an important energy storage device, although a sodium-ion battery has many potentials, currently the traditional cathode materials are mainly oxides.

[0003] For example, CN105226268A discloses a sodium-ion cathode material with a ternary layered structure and a preparation method thereof. The sodium-ion cathode material with a ternary layered structure includes Na

[0004] , b , y , x , a ,

[0006] ,

[0005] , , , Ni 1 / 3 Ti x Mn 2 / 3-x O2, where 0 < X < 2 / 3. However, the traditional layered transition metal oxides have insufficient conductivity during high-rate discharge, resulting in energy loss and heat generation. The ion diffusion channels of the layered structure are often narrow, affecting the rapid insertion and extraction of sodium ions, leading to a decline in rate performance. During high-rate cycling, the material structure is easily damaged, resulting in a rapid decay of battery performance.

[0004] In summary, the defects of sodium-ion batteries mainly focus on the problems such as the often narrow ion diffusion channels of the layered structure and the insufficient conductivity of traditional layered transition metal oxides during high-rate discharge. It is necessary to develop new cathode materials to improve the problems existing in the prior art. Summary of the Invention

[0005] Aiming at the problems such as the insufficient conductivity of the traditional layered transition metal oxides in the cathode materials of existing sodium-ion batteries during high-rate discharge, the present invention provides a nitrogen-containing cathode material and a preparation method thereof, a cathode using the cathode material, and a sodium-ion battery. The present invention optimizes the microstructure and conductivity of the material to improve its performance under high-rate discharge conditions and meet the requirements of rapid charging and high-power discharge.

[0006] To achieve the above object of the present invention, in the first aspect of the present invention, a nitrogen-containing cathode material is provided. The cathode material has the composition shown in Formula I: Na x (M a N b )N yFormula I, where M is selected from transition metal elements; N is nitrogen; N exists in two forms; where 0.5≤x≤1.5, 0.1≤a≤0.9, 0.1≤b≤0.9, and 0.5≤y≤1.5. In this invention, nitrogen exists in two forms: one is a transition metal nitrogen bond of form MN, and the other is isolated nitrogen. Preferably, the isolated nitrogen is intercalated and / or doped nitrogen atoms. Due to the presence of nitrogen bonds of form MN, a=b is preferred. The chemical bonds and vibrations can be characterized and distinguished by XPS and FTIR analysis. During the preparation process, the generation of the two types of nitrogen is controlled by adjusting the nitrogen source and nitrogen atmosphere, temperature and time control, and precursor selection. By optimizing the structural design of nitrides and introducing nitrides, combined with transition metal elements, the cathode material of this invention exhibits excellent structural stability during charge and discharge, and no phase transition phenomenon is observed, ensuring the long-term stability of the battery.

[0007] According to some embodiments of the present invention, the content of N is not less than 20 mol%, preferably 25-50 mol%. In the present invention, at the preferred molar percentage, the nitride structure not only acts as a stabilizer but also improves the electrochemical performance of the material.

[0008] According to some embodiments of the present invention, at least one of Ti, V, Cr, Mn, Fe, Co, and Ni is selected. In the present invention, a is the sum of all M, for example, if M is Mn, Co, and Ni, then a is the sum of Mn, Co, and Ni.

[0009] According to some embodiments of the present invention, the positive electrode material has a layered structure.

[0010] In this invention, it can be determined by conventional characterization methods in the art such as SEM, TEM or XRD that the cathode material of this invention has a layered structure.

[0011] According to some embodiments of the present invention, the average particle size of the cathode material is 1-5 μm.

[0012] According to some embodiments of the present invention, the specific surface area of ​​the positive electrode material is 10-50 m². 2 / g.

[0013] According to some embodiments of the present invention, the XRD pattern of the cathode material has characteristic strong diffraction peaks at positions of 18°, 35°, and 55°.

[0014] A second aspect of the present invention provides a method for preparing the above-mentioned nitrogen-containing cathode material, comprising:

[0015] Step 1: Mix sodium source, M source and nitrogen source, and calcine in nitrogen atmosphere to obtain calcined product, wherein the nitrogen source is selected from ammonia and / or urea;

[0016] Step 2: Anneal the calcined product, perform surface treatment and mechanization treatment.

[0017] According to some embodiments of the present invention, the mixing method is a wet ball milling method. Preferably, the ball milling conditions include: a ball milling speed of 300-500 rpm and a time of 6-12 hours.

[0018] According to some embodiments of the present invention, the calcination is high-temperature calcination, and more preferably, the calcination conditions include: a temperature of 800-1000°C and a time of 8-24 hours.

[0019] According to some embodiments of the present invention, if ammonia is used, the gas flow rate of the ammonia is 50-200 mL / min relative to each 1-5 g mixture of sodium source and M source. In the present invention, the solid substances of Na source and M source are mixed uniformly, and the reaction is ensured by controlling the flow rate of the ammonia atmosphere and the calcination temperature, thereby controlling the generation of the two nitrogen sources.

[0020] According to some embodiments of the present invention, if urea is used, it is directly and uniformly mixed with Na source and M source in solid form, and the generation of the two nitrogen sources is controlled by adjusting the dosage, calcination temperature and time.

[0021] According to some embodiments of the present invention, the annealing conditions include cooling from the calcination temperature to 20-25°C at a cooling rate of 5-10°C / h.

[0022] According to some embodiments of the present invention, the surface treatment is a chemical vapor deposition method; preferably, the conditions for the surface treatment include: a temperature of 400-600°C and a time of 2-6 hours.

[0023] The mechanized processing method is ball milling; preferably, the ball milling conditions include: rotation speed of 300-500 rpm and time of 4-8 hours.

[0024] According to some embodiments of the present invention, the sodium source is a sodium salt or a sodium compound; preferably, the niobium source is selected from at least one of sodium carbonate, sodium hydroxide, sodium nitrate, and sodium chloride.

[0025] According to some embodiments of the present invention, the M source is a salt of a transition metal element, preferably, the M source is selected from at least one of Ti source, V source, Cr source, Mn source, Fe source, Co source and Ni source.

[0026] According to some embodiments of the present invention, the Mn source is a Mn salt and / or an oxide of Mn. Preferably, the manganese source is selected from at least one of manganese oxide, manganese dioxide, manganese carbonate, manganese nitrate, manganese sulfate, manganese chloride, manganese acetate, manganese oxalate, manganese acetylacetone, and manganese formate.

[0027] The Ni source is a Ni salt and / or an oxide of Ni. Preferably, the nickel source is selected from at least one of nickel oxide, nickel carbonate, nickel nitrate, nickel sulfate, nickel chloride, nickel acetate, nickel oxalate, nickel acetylacetone, and nickel formate.

[0028] The Co source is a Co salt and / or an oxide of Co. Preferably, the cobalt source is selected from at least one of cobalt oxide, cobalt carbonate, cobalt nitrate, cobalt sulfate, cobalt chloride, cobalt acetate, cobalt oxalate, cobalt acetylacetonate, and cobalt formate.

[0029] According to some embodiments of the present invention, the amounts of sodium source, M source, nitrogen source, and nitrogen gas satisfy n(Na):n(M):n(N1):n(N2)=x:a:b:y. In the present invention, a is the sum of all M, for example, if M is Mn, Co, and Ni, then a is the sum of Mn, Co, and Ni.

[0030] A third aspect of the present invention provides a positive electrode comprising the nitrogen-containing positive electrode material described above. In the present invention, the method for preparing the positive electrode may include, but is not limited to, coating the nitrogen-containing positive electrode material onto a current collector to obtain the positive electrode.

[0031] The fourth aspect of the present invention provides a method for preparing the above-mentioned positive electrode, comprising: coating the above-mentioned nitrogen-containing positive electrode material onto a current collector to obtain a positive electrode.

[0032] The fifth aspect of the present invention provides a sodium-ion battery, comprising the above-described positive electrode, separator, electrolyte and negative electrode.

[0033] Beneficial effects of the present invention

[0034] (1) The chemical formula of the sodium-ion battery cathode material of this invention is Na x (M a N b )N yIn this invention, M represents the doped transition metal element (such as titanium, vanadium, chromium, manganese, etc.). The layered structure of the nitride effectively enhances the migration ability of sodium ions and improves conductivity through doping. The layered structure of the nitride provides larger ion diffusion channels, increasing the insertion and extraction rates of sodium ions. Simultaneously, by adjusting the synthesis conditions to optimize the conductivity of the nitride, the conductivity of the material is significantly improved during high-rate discharge. The conductivity of the nitride of this invention is significantly better than that of traditional oxides, significantly reducing internal resistance and ensuring efficient energy transfer during rapid charge and discharge. In high-rate cycling tests, the material exhibits a cycle decay rate of less than 3%, demonstrating excellent long-term stability.

[0035] (2) Through special synthesis process and doping strategy, the cathode material of the present invention can still maintain a high discharge capacity at 5C and 10C rates, with a capacity retention rate of over 90%. Detailed Implementation

[0036] In the following technical description, for ease of explanation, numerous details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be practiced without these details.

[0037] The terms "first," "second," etc., used in the specification and claims of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0038] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0039] In this invention, the elemental composition of the cathode material is determined using an inductively coupled plasma method.

[0040] In this invention, the average particle size of the cathode material is measured using a laser particle size analyzer.

[0041] In this invention, the specific surface area of ​​the cathode material is measured using the BET method.

[0042] In this invention, the conductivity of the cathode material is measured by electrochemical impedance spectroscopy.

[0043] Example 1

[0044] Na₂CO₃ and MnO₂ were mixed, with the ratios of Na₂CO₃ and MnO₂ satisfying a ratio of n(Na):n(Mn) = 1:0.8 for the cathode material. Wet ball milling was performed under nitrogen atmosphere for 8 hours at 400 rpm. The mixture was then calcined at 850℃ for 12 hours in an ammonia atmosphere at a flow rate of 100 mL / min. After calcination, the material was annealed, cooled from the calcination temperature to 25℃ at a rate of 5℃ / min, followed by chemical vapor deposition at 500℃ for 4 hours. Mechanized processing was then performed by ball milling at 400 rpm for 6 hours to prepare a layered cathode material. XRD and XPS analysis confirmed that the cathode material was Na(MnO₂)₃:n(MnO₂)₃. 0.8 N 0.8 )N 0.5 The average particle size is 3 μm, and the specific surface area is 25 m². 2 / g. The XRD pattern of the cathode material shows characteristic strong diffraction peaks at positions of 18.5°, 35.2°, and 55.8°.

[0045] Example 2

[0046] Na₂CO₃ and MnO₂ were mixed, with the ratios of Na₂CO₃ and MnO₂ satisfying a ratio of n(Na):n(Mn) = 1:0.6 for the cathode material. Wet ball milling was performed under nitrogen atmosphere for 8 hours at 400 rpm. The mixture was then calcined at 850℃ for 12 hours in an ammonia atmosphere at a flow rate of 100 mL / min. After calcination, the material was annealed, cooled from the calcination temperature to 25℃ at a rate of 5℃ / min, followed by chemical vapor deposition at 500℃ for 4 hours. Mechanized processing was then performed by ball milling at 400 rpm for 6 hours to prepare a layered cathode material. Analysis revealed that this cathode material was Na(MnO₂)₃:n(MnO₂)₃. 0.6 N 0.6 )N 0.5 The average particle size is 3.1 μm, and the specific surface area is 24.2 m². 2 / g. The XRD pattern of the cathode material shows characteristic strong diffraction peaks at positions of 18.4°, 35.3°, and 55.0°.

[0047] Example 3

[0048] Na₂CO₃ and MnO₂ were mixed, with the ratios of Na₂CO₃ and MnO₂ satisfying a ratio of n(Na):n(Mn) = 1:0.7 for the cathode material. Wet ball milling was performed under nitrogen atmosphere for 8 hours at 400 rpm. The mixture was then calcined at 850℃ for 12 hours in an ammonia atmosphere at a flow rate of 100 mL / min. After calcination, the material was annealed, cooled from the calcination temperature to 25℃ at a rate of 5℃ / min, followed by chemical vapor deposition at 500℃ for 4 hours. Mechanized processing was then performed by ball milling at 400 rpm for 6 hours to prepare a layered cathode material. Analysis revealed that this cathode material was Na(MnO₂)₃:n(MnO₂)₃. 0.7 N 0.7 )N 0.5 The average particle size is 3.5 μm, and the specific surface area is 22.1 m². 2 / g. The XRD pattern of the cathode material shows characteristic strong diffraction peaks at positions of 18.0°, 35.4°, and 55.2°.

[0049] Example 4

[0050] NaCl and MnCl2 were mixed, with the amounts of NaCl and MnCl2 satisfying the ratio of n(Na):n(Mn) = 1:0.8 for the cathode material. Wet ball milling was performed under nitrogen atmosphere for 8 hours at 400 rpm. The mixture was then calcined at 850℃ for 12 hours in an ammonia atmosphere at a flow rate of 100 mL / min. After calcination, the material was annealed, cooled from the calcination temperature to 25℃ at a cooling rate of 5℃ / min, followed by chemical vapor deposition at 500℃ for 4 hours. Mechanized processing was then performed by ball milling at 400 rpm for 6 hours to prepare a layered cathode material. Analysis revealed that this cathode material was Na(Mn)Cl2. 0.8 N 0.8 )N 0.5 The average particle size is 2.9 μm, and the specific surface area is 26.1 m². 2 / g. The XRD pattern of the cathode material shows characteristic strong diffraction peaks at positions of 18.1°, 35.0°, and 55.1°.

[0051] Example 5

[0052] Na₂CO₃ and MnO₂ were mixed, with the amounts of Na₂CO₃ and MnO₂ satisfying the ratio of n(Na):n(Mn) = 1:0.8 for the cathode material. Wet ball milling was performed under nitrogen atmosphere for 12 hours at 300 rpm. The mixture was then calcined at 900℃ for 12 hours in an ammonia atmosphere at a flow rate of 100 mL / min. After calcination, the material was annealed, cooled from the calcination temperature to 25℃ at a cooling rate of 5℃ / min, followed by chemical vapor deposition at 400℃ for 6 hours. Mechanized processing was then performed by ball milling at 300 rpm for 8 hours to prepare a layered cathode material. Analysis revealed that this cathode material was Na(Mn)₂CO₃:n(Mn)₂. 0.8 N 0.8 )N 0.5 The average particle size is 3.6 μm, and the specific surface area is 18.6 m². 2 / g. The XRD pattern of the cathode material shows characteristic strong diffraction peaks at positions of 18.6°, 35.5°, and 55.2°.

[0053] Example 6

[0054] Na₂CO₃, MnO₂, and urea were mixed, with the proportions of Na₂CO₃, MnO₂, and urea satisfying the ratio of n(Na):n(Mn):n(N) for the cathode material being 1:0.8:0.8. Wet ball milling was performed under nitrogen atmosphere for 12 hours at 300 rpm. The mixture was then calcined at 900℃ for 8 hours. After calcination, the material was annealed, cooled from the calcination temperature to 25℃ at a rate of 5℃ / min, followed by chemical vapor deposition at 400℃ for 6 hours. Mechanized processing was then performed by ball milling at 300 rpm for 8 hours to produce a layered cathode material. Testing confirmed that this cathode material was Na(MnO₂):n(N) = 1:0.8:0.8. 0.8 N 0.8 )N 0.5 The average particle size is 3.6 μm, and the specific surface area is 18.6 m². 2 / g. The XRD pattern of the cathode material shows characteristic strong diffraction peaks at positions of 18.6°, 35.5°, and 55.2°.

[0055] Example 7

[0056] Na₂CO₃ and MnO₂ were mixed, with the ratios of Na₂CO₃ and MnO₂ satisfying a ratio of n(Na):n(Mn) = 1:0.8 for the cathode material. Wet ball milling was performed under nitrogen atmosphere for 8 hours at 400 rpm. The mixture was then calcined at 1000℃ for 24 hours in an ammonia atmosphere at a flow rate of 100 mL / min. After calcination, the material was annealed, cooled from the calcination temperature to 25℃ at a rate of 5℃ / min, followed by chemical vapor deposition at 500℃ for 4 hours. Mechanized processing was then performed by ball milling at 400 rpm for 6 hours to prepare a layered cathode material. Analysis revealed that this cathode material was Na(MnO₂)₃:n(MnO₂)₃. 0.8 N 0.8 N1 has an average particle size of 3.8 μm and a specific surface area of ​​15.5 m². 2 / g. The XRD pattern of the cathode material shows characteristic strong diffraction peaks at positions of 18.2°, 35.2°, and 55.0°.

[0057] Comparative Example 1

[0058] The method is the same as in Example 1, except that ammonia is replaced with nitrogen, that is:

[0059] Na₂CO₃ and MnO₂ were mixed, with the ratios of Na₂CO₃ and MnO₂ satisfying a ratio of n(Na):n(Mn) = 1:0.8 for the cathode material. Wet ball milling was performed under nitrogen atmosphere for 8 hours at 400 rpm. The mixture was then calcined at 850℃ for 12 hours in a nitrogen atmosphere at a flow rate of 100 mL / min. After calcination, the material was annealed, cooled from the calcination temperature to 25℃ at a cooling rate of 5℃ / min, followed by chemical vapor deposition at 500℃ for 4 hours. Mechanized processing was then performed by ball milling at 400 rpm for 6 hours to prepare a layered cathode material. Testing confirmed that the cathode material was NaMn. 0.8 N 0.5 The average particle size is 3 μm, and the specific surface area is 25 m². 2 / g. The XRD pattern of the cathode material shows characteristic strong diffraction peaks at positions 19.2° and 50.5°.

[0060] Comparative Example 2

[0061] The method is the same as in Example 1, except that nitrogen is replaced with oxygen, that is:

[0062] Na₂CO₃ and MnO₂ were mixed, with the amounts of Na₂CO₃ and MnO₂ satisfying the ratio of n(Na):n(Mn) = 1:0.8 for the cathode material. Wet ball milling was performed in an oxygen-rich environment for 8 hours at 400 rpm. The mixture was then calcined at 850°C for 12 hours in an ammonia atmosphere at a flow rate of 100 mL / min. After calcination, the material was annealed, cooled from the calcination temperature to 25°C at a rate of 5°C / min, followed by chemical vapor deposition at 500°C for 4 hours. Mechanized processing was then performed by ball milling at 400 rpm for 6 hours to produce a layered cathode material. Analysis confirmed that this cathode material was Na(Mn)₂CO₃:n(Mn)₂. 0.8 N 0.8 )O 0.5 The average particle size is 10.9 μm, and the specific surface area is 1.2 m². 2 / g. The XRD pattern of the cathode material shows characteristic strong diffraction peaks at positions of 17.4°, 30.5°, and 49.2°.

[0063] Comparative Example 3

[0064] The method is the same as in Example 1, except that nitrogen is replaced with air, that is:

[0065] Na₂CO₃ and MnO₂ were mixed, with the ratios of Na₂CO₃ and MnO₂ satisfying a ratio of n(Na):n(Mn) = 1:0.8 for the cathode material. The mixture was then wet-milled in air for 8 hours at 400 rpm. The mixture was then calcined at 850°C for 12 hours in an ammonia atmosphere at a flow rate of 100 mL / min. After calcination, the material was annealed, cooled from the calcination temperature to 25°C at a rate of 5°C / min, followed by chemical vapor deposition at 500°C for 4 hours. Finally, the mixture was mechanically milled at 400 rpm for 6 hours to produce a layered cathode material. Testing confirmed that this cathode material was NaMn. 0.8 N 0.3 The average particle size is 12.9 μm, and the specific surface area is 3.6 m². 2 / g. The XRD pattern of the cathode material shows characteristic strong diffraction peaks at positions 17.1° and 34.2°.

[0066] Comparative Example 4

[0067] The method is the same as in Example 1, except that MnO2 is not used, that is:

[0068] Na₂CO₃ was added to a nitrogen atmosphere and wet ball milled for 8 hours at 400 rpm. The mixture was then placed in an ammonia atmosphere at a flow rate of 100 mL / min and calcined at 850 °C for 12 hours. After calcination, the material was annealed by cooling from the calcination temperature to 25 °C at a cooling rate of 5 °C / min, followed by chemical vapor deposition at 500 °C for 4 hours. Mechanized processing was then performed by ball milling at 400 rpm for 6 hours to prepare a layered cathode material. Analysis revealed sodium and nitrogen-containing metal compounds with an average particle size of 20.1 μm and a specific surface area of ​​1.7 m². 2 / g. The XRD pattern of the cathode material shows a characteristic strong diffraction peak at a position of 16.5°.

[0069] Test case

[0070] The positive electrode materials obtained in the examples and comparative examples were coated onto aluminum foil current collectors to obtain positive electrodes. Then, they were assembled with glass fiber membrane separators, 1M NaPF6 solution electrolyte and sodium metal negative electrodes using conventional methods to obtain batteries.

[0071] The assembled batteries were subjected to charge-discharge cycle tests under the following conditions: a charge-discharge rate of 1C and a cycle voltage range of 2.0V to 4.2V. The discharge specific capacity after 100 cycles at 1C, 5C, and 10C rates is shown in Table 1.

[0072] Table 1

[0073]

[0074]

[0075] As can be seen from Table 1, the cathode material can still maintain a high discharge capacity at 5C and 10C rates, and the capacity retention rate remains at a high level.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A nitrogen-containing cathode material, characterized in that, The positive electrode material has a composition shown in Formula I: Na x (M a N b )N y (Formula I), wherein M is selected from transition metal elements; N is nitrogen; N has two forms of existence; wherein, 0.5≤x≤1.5, 0.1≤a≤0.9, 0.1≤b≤0.9, 0.5≤y≤1.

5.

2. The nitrogen-containing cathode material of claim 1, wherein, The content of N is not less than 20 mol%, preferably 25-50 mol%.

3. The nitrogen-containing positive electrode material according to claim 1 or 2, characterized in that, The M is selected from at least one of Ti, V, Cr, Mn, Fe, Co and Ni.

4. The nitrogen-containing positive electrode material of any one of claims 1-3, wherein, The positive electrode material has a layered structure. Preferably, the average particle size of the positive electrode material is 1-5 μm. Preferably, the specific surface area of the positive electrode material is 10-50 m 2 / g; Preferably, the XRD pattern of the positive electrode material has diffraction peaks at 18°, 35° and 55°.

5. A preparation method of the nitrogen-containing positive electrode material according to any one of claims 1-4, comprising: Step 1, mixing a sodium source, an M source and a nitrogen source, and calcining in a nitrogen atmosphere to obtain a calcined product, wherein the nitrogen source is selected from ammonia and / or urea; Step 2, annealing treatment, surface treatment and mechanization treatment of the calcined product.

6. The preparation method according to claim 5, characterized in that, The mixing method is a wet ball milling method; preferably, the ball milling conditions include a ball milling rotation speed of 300-500 rpm and a time of 6-12 hours; and / or, The calcining is high-temperature calcining; preferably, the calcining conditions include a temperature of 800-1000℃ and a time of 8-24 h; and / or, The gas flow rate of the ammonia is 50-200 mL / min per 1-5 g of the mixture of the sodium source and the M source; and / or, The annealing treatment conditions include cooling from the calcining temperature to 20-25℃ at a cooling rate of 5-10℃ / h; and / or, The surface treatment is chemical vapor deposition; preferably, the surface treatment conditions include a temperature of 400-600℃ and a time of 2-6 hours; and / or, The mechanization treatment method is ball milling; preferably, the ball milling conditions include a rotation speed of 300-500 rpm and a time of 4-8 hours.

7. The production method according to claim 5 or 6, characterized by, The sodium source is a sodium salt or a sodium compound; preferably, the niobium source is selected from at least one of sodium carbonate, sodium hydroxide, sodium nitrate and sodium chloride; and / or, The M source is a salt of a transition metal element, preferably the M source is selected from at least one of a Ti source, a V source, a Cr source, a Mn source, a Fe source, a Co source and a Ni source; and / or, The amounts of the sodium source, the M source, the nitrogen source and the nitrogen gas satisfy n(Na):n(M):n(N1):n(N2)=x:a:b:y.

8. A positive electrode comprising the nitrogen-containing positive electrode material according to any one of claims 1-4.

9. The method of producing a positive electrode as claimed in claim 8, comprising: The nitrogen-containing positive electrode material according to any one of claims 1-4 is coated on a current collector to obtain a positive electrode.

10. A sodium ion battery comprising the positive electrode according to claim 9, a separator, an electrolyte and a negative electrode.

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