Nickel sodium manganate positive electrode material with core-shell spherical structure, and preparation method and application of nickel sodium manganate positive electrode material

Abstract

The invention discloses a sodium nickel manganese oxide positive electrode material with a core-shell spherical structure and a preparation method and application thereof, the material has a P2 type layered structure, the morphology is a core-shell structure, and the chemical general formula is shown in the specification. When the Ni is doped into the P2 layered oxide, the Ni and the O atom form a strong Ni-O bond to improve the binding energy, and then the Ni and the Mn atom share the O atom to form a Mn-O-Ni covalent bond, so that the stability of a crystal structure is enhanced, and lattice expansion is slowed down. The core-shell spherical structure of the positive electrode material is rough in surface and internally provided with multiple cavities, can wrap an inner layer material, reduces direct contact with electrolyte, prevents dissolution, reduces side reaction, and also can reduce volume expansion of the core during charging and discharging, inhibit phase change and improve structural stability. In addition, the structure optimizes and shortens an electron conduction path, reduces internal resistance, improves rate capability and cycling stability, and has important application value in the fields of sodium ion battery electrode preparation and energy storage equipment research.

Description

Technical Field

[0001] This invention belongs to the field of manganese-based sodium electrode materials technology, specifically relating to a core-shell spherical structure sodium nickel manganate cathode material, its preparation method, and its application. Background Technology

[0002] Against the backdrop of global energy structure transformation, the limited reserves of traditional fossil fuels and the gradual deterioration of the ecological environment have made the research and development of new energy technologies a key factor concerning human sustainable development. As an important research direction in the field of energy storage, sodium-ion battery technology, due to its resource advantages and cost-effectiveness, is gradually becoming a powerful alternative to lithium-ion batteries. Particularly in the research of cathode materials, the innovative discovery of manganese-based layered oxides has opened up new avenues for developing high-performance, economical sodium-ion batteries. Among them, P2-type layered oxides, with their unique crystal structure and excellent electrochemical properties, have become one of the most promising cathode materials in this field, attracting significant attention from academia and industry. These materials possess dual advantages in energy density and cost control, providing crucial technical support for promoting the industrialization of sodium-ion batteries.

[0003] P2-type layered metal oxides have the advantage of being spacious. Due to their ion transport channels, ease of synthesis, and high specific capacity, manganese-based materials occupy an important position in the research of cathode materials for sodium-ion batteries, especially those with excellent overall performance. However, these materials still face many challenges in practical applications, such as the tendency to exhibit the Jahn-Teller effect; and... The low reaction potential of redox pairs inhibits the improvement of energy density; phase transitions easily occur at operating voltages above 4.0V, leading to poor cycle stability. Researchers are working to address these issues through various material modification techniques, primarily including elemental doping to control crystal structure, ion substitution to optimize electronic properties, and surface coating to improve interfacial stability. The development and application of these techniques have significant practical value for improving the structural stability of P2-type layered oxides under high-voltage conditions and represent an important research direction in the field of sodium-ion batteries.

[0004] Patent document CN202410583789.1 discloses a double-site doped sodium nickel iron manganese oxide cathode material, its preparation method, and its application. The general structural formula of the double-site doped sodium nickel iron manganese oxide cathode material is: The preparation method includes the following steps: dissolving nickel, iron, and manganese salts in an alcohol-containing solvent, adding ascorbic acid M salt to obtain a mixed solution; adding a complexing agent and a precipitating agent to the mixed solution, and carrying out a co-precipitation reaction under an inert gas atmosphere to obtain an M-doped nickel-iron-manganese hydroxide precursor; mixing sodium and potassium salts evenly, adding them to the M-doped nickel-iron-manganese hydroxide precursor, mixing evenly, sintering under an oxidizing gas atmosphere, and then cooling under an inert gas atmosphere to obtain the dual-site doped sodium nickel-iron-manganese oxide cathode material. Dual-site doping can improve the specific capacity, initial efficiency, and capacity cycle stability of the cathode material.

[0005] To address the aforementioned deficiencies, current research mainly focuses on the following improvement strategies: (1) Element doping: By introducing elements such as Ni, W, Ti, Zn, and La, the layered structure is stabilized and phase transitions are suppressed; (2) Surface modification: Carbon coating or perovskite modification is used to reduce side reactions between the electrolyte and active materials, thereby improving interface stability; (3) Anion redox regulation: Activating oxygen anions to participate in charge compensation, replacing some transition metal redox reactions, and reducing structural stress. These improvement strategies have significantly improved P2- The improved cycle life and rate performance laid the foundation for its commercial application. However, the aforementioned improvement strategies still need further enhancement and optimization. Summary of the Invention

[0006] The key technical problem solved by this invention is to provide a synthesis and application of a core-shell spherical sodium nickel manganate cathode material. The method uses a simple experimental apparatus to synthesize the core-shell spherical sodium nickel manganate cathode material through a high-temperature solid-state method. The prepared core-shell spherical sodium nickel manganate cathode material, as an electrode for sodium-ion batteries, has high specific energy and cycle stability.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a core-shell spherical sodium nickel manganate cathode material, wherein the cathode material is a single crystal with a P2-type layered structure, and its general chemical formula is [insert chemical formula here]. , where 0≤y≤0.6.

[0008] Furthermore, the cathode material contains a stable network structure composed of Ni-O bonds and Mn-O-Ni covalent bonds. The synthesized... The cathode material exhibits a core-shell spherical structure with a rough surface and numerous internal cavities. This unique structure encapsulates the inner layer material, reducing direct contact between the inner layer and the electrolyte, and effectively preventing the electrolyte from entering the core material. This dissolves the substance, thereby reducing the occurrence of side reactions.

[0009] This invention provides a method for preparing the above-mentioned core-shell spherical structure sodium nickel manganate cathode material, the preparation of which includes the following steps: S1 Preparation by co-precipitation method. Precursor; S2 will prepare the The precursor powder was thoroughly mixed with an excess sodium source, and the core-shell spherical sodium nickel manganate cathode material was finally prepared by a high-temperature solid-state method. .

[0010] Furthermore, in step S1, the manganese source used in the co-precipitation method is... , , or Nickel source is , , or .

[0011] Furthermore, in step S2, a high-temperature solid-state method is used. The mixed materials are placed in a muffle furnace and sintered at a high temperature of 700°C to 900°C for 4 to 15 hours to finally obtain the sodium nickel manganate cathode material with the core-shell spherical structure described above. .

[0012] Furthermore, the sodium source mentioned in step S2 is... , , or The reaction atmosphere is air; the heating rate for high-temperature sintering is 3~10℃ / min.

[0013] Furthermore, the aforementioned The specific preparation steps of the precursor are as follows: According to the stoichiometric ratio, and Prepare a 150-250 mL mixed solution A by adding 50-150 mL of anhydrous ethanol; solution B is prepared by adding 30 mmol of... Dissolve the A solution in 150-250 mL of deionized water; place the beaker containing solution A in a constant temperature water bath at 50°C; then add the prepared solution B to solution A, and continue aging for 0.5-1.5 hours, maintaining constant temperature and stirring at a uniform speed throughout the process; finally, centrifuge and wash the precipitate obtained from the reaction, and then dry it at 80°C to obtain spherical precipitates. The precursor is a yellowish-brown powder.

[0014] Furthermore, the specific preparation steps of the cathode material are as follows: 5% excess of 7.35 mmol NaOH and 10 mmol... Anhydrous ethanol was added sequentially to an agate mortar and pestle, and the mixture was thoroughly ground into a slurry under a heat lamp and dried. The slurry was then removed, ground into powder, placed in a porcelain boat, and then placed in a muffle furnace. The temperature was increased to 750–850°C at a rate of 3–6°C / min and held for 6–15 hours, finally yielding a black powder. Positive electrode material.

[0015] Ni element is incorporated into P2- Within the crystal lattice of the cathode material, it is possible to successfully construct... Cathode materials. In this process, the introduction of Ni has a significant positive impact on the material's structure. Specifically, the main particles of the material are primarily composed of elements such as manganese and oxygen, which constitute the basic structural units. After Ni doping, these main particles stack more tightly, orderly, and regularly in layers along specific crystallographic directions, effectively optimizing the arrangement of the main particles. When Ni is doped into P2 layered oxides, it first forms strong Ni-O bonds with O atoms, thereby increasing the binding energy; subsequently, Ni atoms share O atoms with Mn atoms, forming Mn-O-Ni covalent bonds. This process not only enhances the stability of the crystal structure but also effectively mitigates lattice expansion. Synthesized The cathode material exhibits a core-shell spherical structure with a rough surface and numerous internal cavities. This unique structure encapsulates the inner layer material, reducing direct contact between the inner layer and the electrolyte, and effectively preventing the electrolyte from entering the core material. This method facilitates dissolution and reduces side reactions. Furthermore, it effectively mitigates the volume expansion of the core material during charge and discharge, suppresses phase transitions, and significantly improves its structural stability. Simultaneously, this structural optimization shortens the electron conduction path, reduces internal resistance, and thus enhances rate performance and cycle stability.

[0016] This invention also provides a sodium-ion battery, comprising the core-shell spherical structure sodium nickel manganate positive electrode material as described in any one of claims 1 or 2. The specific assembly process is as follows: the core-shell spherical structure sodium nickel manganate positive electrode material is mixed with conductive agent acetylene black and binder polyvinylidene fluoride in a mass ratio of 7-8:1-2:1, using N-methylpyrrolidone as a solvent, and ground in an agate mortar under an infrared lamp to obtain a slurry. The slurry is coated onto a current collector aluminum foil and transferred to a vacuum drying oven at 80-130°C for 8 hours to prepare an electrode sheet with a diameter of 10-14 mm. The electrode is then placed in an argon-filled glove box for 1-4 hours to reduce moisture adsorbed during the transfer process. Finally, it is assembled into a CR2032 type coin cell in the glove box, using a circular commercial sodium sheet as the negative electrode, with a concentration of 1 mol / L... The solution was used as the electrolyte, and a glass fiber membrane with a diameter of 16 mm was used as the separator. The battery was aged for 8 hours after assembly.

[0017] The present invention also provides the application of the above-mentioned core-shell spherical structure sodium nickel manganate cathode material in sodium-ion batteries.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0019] (1) The core-shell spherical structure sodium nickel manganate cathode material prepared by the method of the present invention ( Due to its core-shell spherical structure, it has a rough surface and numerous internal cavities. This unique structure encapsulates the inner layer material, reducing direct contact between the inner layer material and the electrolyte, effectively preventing the electrolyte from entering the core material. The dissolution of sodium ion batteries reduces the occurrence of side reactions and is of great value in the preparation of sodium ion battery electrodes and the research of sodium energy storage devices.

[0020] (2) This invention successfully prepared a core-shell spherical sodium nickel manganate cathode material. During the preparation process, Ni first forms a strong Ni-O bond with O atoms to increase the binding energy, and then shares O atoms with Mn atoms to form a Mn-O-Ni covalent bond, which enhances the stability of the crystal structure and slows down the lattice expansion. This core-shell spherical sodium nickel manganate cathode material has excellent performance and great application potential, and is expected to be used in energy storage devices such as sodium-ion secondary batteries.

[0021] (3) The present invention has significant advantages, the process is simple and easy to operate, the experimental process is greatly shortened, the raw materials are easy to obtain and the cost is low, no toxic or harmful substances are generated in the entire preparation process, and the environmental protection is excellent; the overall conditions are mature, and it is very easy to move from the laboratory to large-scale industrial production. Attached Figure Description

[0022] Figure 1 A simplified diagram of the experimental setup for preparing cathode materials.

[0023] Figure 2 The XRD patterns are of the cathode materials of Example 1 and Comparative Examples 1-3.

[0024] Figure 3 Prepared as in Example 1 SEM image of the cathode material.

[0025] Figure 4 Prepared as in Example 1 TEM image.

[0026] Figure 5 The graphs show the long cycle life test results of the cathode materials in Example 1 and Comparative Examples 1-3.

[0027] Figure 6 The above are charge-discharge curves of the cathode materials of Example 1 and Comparative Examples 1-3. Detailed Implementation

[0028] The following examples further illustrate the above-mentioned content of the present invention in detail, but it should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following examples. All technologies implemented based on the above-mentioned content of the present invention fall within the scope of the present invention.

[0029] The following examples and comparative examples utilize experimental apparatus for preparing related materials using high-temperature solid-state reactions, such as... Figure 1 As shown.

[0030] Example 1 ( (NNMO-746)

[0031] (1) Preparation by coprecipitation method Precursor: and Prepare a 210 mL mixed solution A according to a stoichiometric ratio of 6:4, and add 140 mL of anhydrous ethanol. Separately, add 30 mmol... Dissolve the A solution in 210 mL of deionized water to prepare precipitant solution B. Place the beaker containing solution A in a constant temperature water bath at 50 °C. Then, add the prepared solution B to solution A. After the initial step, allow it to age for another 1 hour, maintaining constant temperature and stirring throughout the process. Finally, collect the precipitate by centrifugation, wash repeatedly with deionized water to remove impurities, and dry at 80 °C to obtain a light yellow, spherical precipitate. Precursor powder.

[0032] (2) Using 7.35 mmol NaOH (5% excess) and 10 mmol The raw materials were weighed in the specified proportions, and anhydrous ethanol was used as the solvent. They were then added sequentially to an agate mortar and ground thoroughly into a slurry under an infrared lamp and dried. The slurry was then removed, ground into powder, and placed in a porcelain boat. The pretreated material was placed in a muffle furnace and calcined at high temperature using a programmed temperature control system. First, the temperature was increased to 800 °C at a rate of 5 °C / min, and then maintained at this temperature for 10 h. After the reaction was complete, the furnace was cooled to room temperature to obtain a black powder. Positive electrode material.

[0033] Comparative Example 1 ( (NMO)

[0034] (1) Preparation of MnCO3 precursor by coprecipitation: according to a stoichiometric ratio of 1:0 , Prepare 210 mL of mixed solution A and add 140 mL of anhydrous ethanol. Separately, add 30 mmol... Dissolve the reagent in 210 mL of deionized water to prepare precipitant solution B. Place the beaker containing solution A in a constant temperature water bath at 50 °C. Then, add the prepared solution B to solution A. After the initial step, allow the solution to age for another 1 hour, maintaining constant temperature and stirring throughout the process. Finally, collect the precipitate by centrifugation, wash repeatedly with deionized water to remove impurities, and dry at 80 °C to obtain the final product. Precursor powder.

[0035] (2) Using 7.35 mmol NaOH (5% excess) and 10 mmol The raw materials were weighed in the specified proportions, and anhydrous ethanol was used as the solvent. They were then added sequentially to an agate mortar and ground thoroughly into a slurry under an infrared lamp and dried. The slurry was then removed, ground into powder, and placed in a porcelain boat. The pretreated material was placed in a muffle furnace and calcined at high temperature using a programmed temperature control system. First, the temperature was increased to 800 °C at a rate of 5 °C / min, and then maintained at this temperature for 10 h. After the reaction was complete, the furnace was cooled to room temperature to obtain a black powder. Positive electrode material.

[0036] Comparative Example 2 (Adjusting the doping ratio) (NNMO-728))

[0037] (1) Preparation by coprecipitation method Precursor: in a stoichiometric ratio of 8:2 , Prepare 210 mL of mixed solution A and add 140 mL of anhydrous ethanol. Separately, add 30 mmol... Dissolve the A solution in 210 mL of deionized water to prepare precipitant solution B. Place the beaker containing solution A in a constant temperature water bath at 50 °C. Then, add the prepared solution B to solution A. After the initial step, allow it to age for another 1 hour, maintaining constant temperature and stirring throughout the process. Finally, collect the precipitate by centrifugation, wash repeatedly with deionized water to remove impurities, and dry at 80 °C to obtain a light yellow, spherical precipitate. Precursor powder.

[0038] (2) Using 7.35 mmol NaOH (5% excess) and 10 mmol The raw materials were weighed in the specified proportions, and anhydrous ethanol was used as the solvent. They were then added sequentially to an agate mortar and ground thoroughly into a slurry under an infrared lamp and dried. The slurry was then removed, ground into powder, and placed in a porcelain boat. The pretreated material was placed in a muffle furnace and calcined at high temperature using a programmed temperature control system. First, the temperature was increased to 800 °C at a rate of 5 °C / min, and then maintained at this temperature for 10 h. After the reaction was complete, the furnace was cooled to room temperature to obtain a black powder. Positive electrode material.

[0039] Comparative Example 3 (Adjusting the doping ratio) (NNMO-764))

[0040] (1) Preparation by coprecipitation method Precursor: in a stoichiometric ratio of 4:6 , Prepare 210 mL of mixed solution A and add 140 mL of anhydrous ethanol. Separately, add 30 mmol... Dissolve the A solution in 210 mL of deionized water to prepare precipitant solution B. Place the beaker containing solution A in a constant temperature water bath at 50 °C. Then, add the prepared solution B to solution A. After the initial step, allow it to age for another 1 hour, maintaining constant temperature and stirring throughout the process. Finally, collect the precipitate by centrifugation, wash repeatedly with deionized water to remove impurities, and dry at 80 °C to obtain a light yellow, spherical precipitate. Precursor powder.

[0041] (2) Using 7.35 mmol NaOH (5% excess) and 10 mmol The raw materials were weighed in the specified proportions, and anhydrous ethanol was used as the solvent. They were then added sequentially to an agate mortar and ground thoroughly into a slurry under an infrared lamp and dried. The slurry was then removed, ground into powder, and placed in a porcelain boat. The pretreated material was placed in a muffle furnace and calcined at high temperature using a programmed temperature control system. First, the temperature was increased to 800 °C at a rate of 5 °C / min, and then maintained at this temperature for 10 h. After the reaction was complete, the furnace was cooled to room temperature to obtain a black powder. Positive electrode material.

[0042] Sodium-ion battery assembly is completed using the following method:

[0043] The positive electrode materials obtained in Example 1 and Comparative Examples 1-3, sodium electrode materials, conductive agent acetylene black (Super-p), and binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 8:1:1, and N-methylpyrrolidone (NMP) was used as a solvent. The mixture was placed in an agate mortar and ground under an infrared lamp to obtain a slurry. The slurry was coated onto a current collector aluminum foil and dried in a vacuum drying oven at 110 °C for 8 h to prepare an electrode sheet with a diameter of 10 mm. This electrode was then placed in a glove box filled with argon atmosphere for 3 h to reduce the moisture adsorbed during the transfer process, with both water and oxygen content below 0.1 ppm. Finally, it was assembled into a CR2032 type coin cell in the glove box. A 14 mm diameter circular commercial sodium sheet was used as the negative electrode, with a concentration of 1 mol / L...

[0044] The solution was used as the electrolyte, and a glass fiber membrane with a diameter of 16 mm was used as the separator. The battery was aged for 8 hours after assembly.

[0045] The battery was tested at 2-4 V, at 100... The discharge specific capacity after 300 cycles at the specified current density is shown in Table 1.

[0046] Table 1 Electrochemical properties of the materials

[0047]

[0048] As can be seen from the performance comparison data of Example 1 and Comparative Example 1, the core-shell spherical structure sodium nickel manganate cathode material prepared in this invention ( It exhibits significantly better overall electrochemical performance than undoped P2-. Comparative samples. Specifically, Comparative Example 1, as a pure-phase material, is prone to the Jahn-Teller effect during cycling and... The redox reaction potential is relatively low, which inhibits the improvement of energy density; phase transitions easily occur at operating voltages above 4.0 V, leading to poor cycle stability. In contrast, the core-shell spherical nickel structure of Example 1... The positive electrode material effectively avoids and solves the above problems. Due to its core-shell spherical structure, the cathode material has a rough surface and numerous internal cavities. This unique structure encapsulates the inner layer material, reducing direct contact between the inner layer and the electrolyte, and effectively preventing the electrolyte from entering the core material. The dissolution of Ni-doped P2- reduces the occurrence of side reactions. During the process, Ni first forms a strong Ni-O bond with O atoms to increase the binding energy, and then shares O atoms with Mn atoms to form a Mn-O-Ni covalent bond, which enhances the stability of the crystal structure and slows down lattice expansion. In summary, the success of Example 1 is attributed to the synergistic effect of the core-shell spherical structure and Ni doping, resulting in better electrochemical performance of the material. This comparison fully demonstrates the advancement and necessity of the technical solution of this invention (core-shell spherical structure sodium nickel manganate cathode material).

[0049] Based on the performance comparison data of Example 1 and Comparative Examples 2-3, the effect of Ni doping amount on material properties is reflected in the following two aspects:

[0050] On the one hand, when the Ni doping amount is insufficient, the number of Ni ions entering the sodium manganate lattice is limited, leading to two key problems: First, the number of strong Mn-O-Ni covalent bonds formed is insufficient, failing to effectively suppress structural phase transitions and lattice expansion during charge and discharge; second, although the Ni-O bond energy is higher than that of Mn-O, which helps to weaken Na-O interactions and promote sodium ion diffusion, too few Ni-O bonds cannot significantly expand the interlayer spacing or stabilize the overall structure. Therefore, the material exhibits poor specific capacity and cycle stability.

[0051] On the other hand, excessive Ni doping can also lead to a decrease in electrochemical performance, mainly for the following reasons: First, excessive Ni doping... The introduction of Ni ions can generate significant lattice stress, potentially inducing local structural distortions and thus compromising the stability of the P2-type layered structure during long-term cycling. Secondly, excessive Ni ions with relatively large radii may occupy interstitial sites near the sodium layer or cause… The migration pathway becomes more complex, thereby blocking sodium ion diffusion channels and reducing the rate performance and reversible capacity of the material.

[0052] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from the scope of the principles of the present invention, and all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A core-shell spherical structure sodium nickel manganate cathode material, characterized in that, The cathode material is a single crystal with a P2-type layered structure, and its general chemical formula is: , where 0≤y≤0.

6.

2. The core-shell spherical structure sodium nickel manganate cathode material according to claim 1, characterized in that, The cathode material contains a stable network structure composed of Ni-O bonds and Mn-O-Ni covalent bonds.

3. A method for preparing the core-shell spherical structured sodium nickel manganate cathode material according to any one of claims 1 or 2, characterized in that, The preparation includes the following steps: S1 was prepared by coprecipitation method. Precursor; S2 will prepare the The precursor powder was thoroughly mixed with an excess sodium source, and the core-shell spherical sodium nickel manganate cathode material was finally prepared by a high-temperature solid-state method. .

4. The method for preparing the core-shell spherical structured sodium nickel manganate cathode material according to claim 3, characterized in that, In step S1, the manganese source used in the co-precipitation method is... , , or Nickel source is , , or .

5. The method for preparing the core-shell spherical structured sodium nickel manganate cathode material according to claim 4, characterized in that, In step S2, a high-temperature solid-state method is used. The mixed materials are placed in a muffle furnace and sintered at a high temperature of 700°C to 900°C for 4 to 15 hours to finally obtain the sodium nickel manganate cathode material with the core-shell spherical structure described above. .

6. The method for preparing the core-shell spherical structured sodium nickel manganate cathode material according to claim 5, characterized in that, The sodium source mentioned in step S2 is , , or The reaction atmosphere is air. The heating rate for high-temperature sintering is 3~10℃ / min.

7. The method for preparing the core-shell spherical structured sodium nickel manganate cathode material according to claim 6, characterized in that, The The specific preparation steps of the precursor are as follows: According to the stoichiometric ratio, and Prepare a 150-250 mL mixed solution A by adding 50-150 mL of anhydrous ethanol; solution B is prepared by adding 30 mmol of... Dissolve in 150-250 mL of deionized water; Place the beaker containing solution A in a constant temperature water bath at 50°C. Then, add the prepared solution B to solution A. After this process, allow the mixture to age, maintaining the temperature for another 0.5–1.5 hours while keeping the mixture stirred at a constant speed and at a constant temperature. Finally, centrifuge and wash the precipitate obtained from the reaction, then dry it at 80°C to obtain spherical precipitates. The precursor is a yellowish-brown powder.

8. The method for preparing the core-shell spherical structured sodium nickel manganate cathode material according to claim 7, characterized in that, The specific preparation steps of the positive electrode material are as follows: Add excess 5% 7.35 mmol NaOH and 10 mmol... Anhydrous ethanol was added sequentially to an agate mortar and pestle, and the mixture was thoroughly ground into a slurry under a heat lamp and dried. The slurry was then removed, ground into powder, placed in a porcelain boat, and then placed in a muffle furnace. The temperature was increased to 750–850°C at a rate of 3–6°C / min and held for 6–15 hours, finally yielding a black powder. Positive electrode material.

9. A sodium-ion battery, characterized in that, The battery comprises the core-shell spherical structure sodium nickel manganate cathode material as described in any one of claims 1 or 2.

10. The application of a core-shell spherical sodium nickel manganate cathode material according to any one of claims 1 or 2 in a sodium-ion battery.

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