A structurally modified sodium ion battery positive electrode material and preparation method thereof

Abstract

The present invention provides a preparation method of a structure-modified sodium ion battery positive electrode material, comprising the following steps: S1, mixing a sodium source, an iron source, a phosphorus source, a first carbon source, a structure modifier, and deionized water, adding the mixture to a high-gravity reactor rotating at 25,000 to 35,000 rpm, reacting at a temperature of 80 to 100° C. for 1 to 2 h, drying, and then calcining at 400 to 650° C. for 8 to 12 h in an inert gas atmosphere to obtain a precursor, wherein the structure modifier is at least one of sodium vanadate, sodium titanate, sodium manganate, sodium cobaltate, sodium chromate, metatitanic acid, magnesium oxide, copper oxide, zinc oxide, and yttrium oxide; S2, mixing the precursor, a second carbon source, and a chelate solution, adjusting the pH to 2.5 to 4.0, grinding the mixture at a temperature of 60 to 90° C. until the D50 is less than 0.95 μm, spray drying, and calcining at 400 to 650° C. for 8 to 12 h in an inert gas atmosphere. h obtain the structure-modified sodium ion battery positive electrode material.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy battery positive electrode materials, and specifically relates to a structurally modified sodium ion battery positive electrode material and a preparation method thereof. Background Art

[0002] Sodium-ion batteries (SIBs) offer advantages over lithium-ion batteries, such as low cost, long cycle life, and excellent low-temperature performance. As the possibility of replacing lithium-ion batteries has been raised, SIBs are being widely researched. There are three main types of SIBs: layered oxides, Prussian blues, and polyanions. Layered oxides offer high specific capacity but are expensive and have poor cycle performance. Prussian blues are low-cost, but their composition is toxic and their crystal water is difficult to control. Polyanions are low-cost, have good thermal stability, and long cycle life, but suffer from poor conductivity and slow ion migration.

[0003] In the energy storage and small power sectors, safety and affordability are paramount considerations, leading to the significant potential for polyanion sodium-ion batteries in this field. However, their phosphate or pyrophosphate structure and the strong PO bonds result in poor conductivity. Improving this flaw would significantly enhance the application of polyanion sodium-ion batteries. Summary of the Invention

[0004] To this end, the present invention provides a method for preparing a structure-modified sodium ion battery positive electrode material, comprising the following steps: S1, mixing a sodium source, an iron source, a phosphorus source, a first carbon source, a structure modifier, and deionized water, adding the mixture to a high-gravity reactor rotating at a speed of 25000-35000 rpm, reacting at a temperature of 80-100 ° C for 1-2 hours, drying, and then calcining at 400-650 ° C for 6-12 hours in an inert gas atmosphere to obtain a precursor, wherein the structure The modifier is at least one of sodium vanadate, sodium titanate, sodium manganate, sodium cobaltate, sodium chromate, metatitanic acid, magnesium oxide, copper oxide, zinc oxide, and yttrium oxide; S2, mixing the precursor, the second carbon source and the chelate solution, adjusting the pH to 2.5-4.0, grinding at a temperature of 60-90°C until D50 is less than 0.95um, spray drying, and calcining at 400-650°C in an inert gas atmosphere for 8-12h to obtain the structure-modified sodium ion battery positive electrode material.

[0005] Preferably, in step S1, the molar number of sodium element in the sodium source is 2 to 3 times the molar number of iron element in the iron source; and the added amount of the structural modifier is 0.1% to 10% of the mass of the phosphorus source.

[0006] Preferably, the ratio of the molar number of phosphorus in the phosphorus source to the molar number of iron in the iron source is 1.4-2.

[0007] Preferably, the sodium source is at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, and sodium nitrate; the iron source is at least one of ferrous oxalate, ferrous acetate, ferrous citrate, ferrous lactate, and ferric oxide; and the phosphorus source is at least one of pyrophosphoric acid, sodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, phosphoric acid, and sodium phosphate.

[0008] Preferably, the chelate in the chelate solution is a complex formed by a metal ion selected from the group consisting of aluminum, copper, silver, nickel, iron, platinum, potassium, and cobalt and one selected from the group consisting of ethylenediaminetetraacetic acid, citric acid, tartaric acid, tripolyphosphoric acid, hexametaphosphoric acid, aminotriacetic acid, and o-phenanthroline.

[0009] Preferably, the added amount of the chelate is 0.1% to 1% of the mass of the precursor.

[0010] Preferably, the first carbon source and the second carbon source are the same substance or different substances, and the first carbon source and the second carbon source are both selected from at least one of glucose, sucrose, xylitol, polyvinyl alcohol, starch, and cellulose.

[0011] Preferably, the total mass of the first carbon source and the second carbon source accounts for 4% to 9% of the total mass of the sodium source, the iron source, the phosphorus source, the first carbon source, and the second carbon source.

[0012] Preferably, the first carbon source accounts for 50% to 80% of the total mass of the first carbon source and the second carbon source.

[0013] Also provided is a structure-modified sodium ion battery positive electrode material, which is prepared by the above method, and the powder conductivity of the structure-modified sodium ion battery positive electrode material is greater than 7.0×10 -3 S / cm.

[0014] The present invention structurally modifies the positive electrode material of a sodium ion battery. A structural modifier is added in advance when preparing a precursor. The structural modifier's main components are salts and oxides whose anions contain metal elements. During the reaction, the anions replace phosphates or pyrophosphates in the crystal structure of the material. At the same time, metal elements are incorporated into the lattice to replace iron sites, forming lattice defects, widening the ion diffusion channel, reducing the ion diffusion energy barrier, providing a path with good conductivity, and improving the material's conductivity and ion mobility.

[0015] An organic chelating agent is added to the precursor, forming a complex with the metal ions on the crystal surface. Chelates can connect two or more metal ions, primarily used here to connect iron ions and doped metal ions. After carbonization, the organic chelate directly provides a conductive path, improving electrical conductivity. Furthermore, the metal ions in the chelating agent are doped on the crystal surface and in the carbon coating, further enhancing the material's electronic conductivity.

[0016] The reaction of the precursor is carried out in a supergravity reactor with an ultra-high speed of 25,000 to 35,000 rpm, which can generate huge shear force, tear the solution into nanoscale, and enhance the microscopic mixing and reaction mass transfer inside the reaction solution. It not only overcomes the problem of difficult replacement of phosphate or pyrophosphate in the crystal structure, but also makes the replacement elements for modifying the crystal structure evenly distributed, with a particle size as small as nanoscale. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a scanning electron microscope image of the sodium ion battery positive electrode material of Example 1.

[0018] Figure 2 This is the X-ray diffraction pattern of the sodium ion battery positive electrode material of Example 1.

[0019] Figure 3 This is a charge and discharge voltage-specific capacity curve of a button cell assembled with the sodium ion battery positive electrode material of Example 1 at a 0.1C rate.

[0020] Figures 4 to 6 They are scanning electron microscope images of the sodium ion battery positive electrode materials of Comparative Examples 1 to 3, respectively. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described below through specific implementation methods. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of this application.

[0022] The present invention provides a method for preparing a structure-modified sodium ion battery positive electrode material Na4Fe3(PO4)2P2O7, comprising the following steps: S1, mixing a sodium source, an iron source, a phosphorus source, a first carbon source, a structure modifier, and deionized water, adding the mixture to a high-gravity reactor rotating at a speed of 25000-35000 rpm, reacting at a temperature of 80-100°C for 1-2 hours, drying, and then calcining at 400-650°C for 6-12 hours under an inert gas atmosphere to obtain the positive electrode material Na4Fe3(PO4)2P2O7. The structure modifier is at least one of sodium vanadate, sodium titanate, sodium manganate, sodium cobaltate, sodium chromate, metatitanic acid, magnesium oxide, copper oxide, zinc oxide, and yttrium oxide; S2, mixing the precursor, the second carbon source and the chelate solution, adjusting the pH to 2.5-4.0, grinding at a temperature of 60-90°C to a D50 of less than 0.95um, spray drying, and calcining at 400-650°C in an inert gas atmosphere for 8-12h to obtain the structure-modified sodium ion battery positive electrode material.

[0023] In step S1, the molar number of sodium in the sodium source is 2 to 3 times the molar number of iron in the iron source; the amount of the structure modifier added is 0.1% to 10% of the mass of the phosphorus source; and the ratio of the molar number of phosphorus in the phosphorus source to the molar number of iron in the iron source is 1.4 to 2.

[0024] The sodium source is at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, and sodium nitrate; the iron source is at least one of ferrous oxalate, ferrous acetate, ferrous citrate, ferrous lactate, and ferric oxide; and the phosphorus source is at least one of pyrophosphoric acid, sodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, phosphoric acid, and sodium phosphate.

[0025] In step S2, the chelate in the chelate solution is a complex formed by a metal ion in aluminum, copper, silver, nickel, iron, platinum, potassium, cobalt and a metal ion in ethylenediaminetetraacetic acid, citric acid, tartaric acid, tripolyphosphoric acid, hexametaphosphoric acid, nitrilotriacetic acid, o-phenanthroline. For example, the chelate is potassium tartrate, sodium edetate or sodium citrate etc. The chelate can be connected to two or more metal ions with the metal ion complexing of crystal surface, mainly connecting iron ion and doped metal ion. After the chelate reacts with the carbon source to carbonize the chelate, conductive path can be directly provided to improve electrical conductivity.

[0026] The amount of the chelate added is 0.1% to 1% of the mass of the precursor. The first carbon source and the second carbon source are the same substance or different substances, and the first carbon source and the second carbon source are both selected from at least one of glucose, sucrose, xylitol, polyvinyl alcohol, starch, and cellulose. The total mass of the first carbon source and the second carbon source accounts for 4% to 9% of the total mass of the sodium source, the iron source, the phosphorus source, the first carbon source, and the second carbon source. The first carbon source is 50% to 80% of the total mass of the first carbon source and the second carbon source. When the first carbon source and the second carbon source are different substances, for example, the first carbon source is glucose and the second carbon source is sucrose, or the first carbon source is glucose and the second carbon source is polyethylene glycol, etc.

[0027] The inert gas atmosphere refers to argon, nitrogen, or a combination of the two. The amount of the structure modifier and the chelate added is small, and the molecular formula of the sodium ion battery cathode material after structural modification is still represented by Na4Fe3(PO4)2P2O7.

[0028] Several specific embodiments are listed below to further illustrate the present invention.

[0029] Example 1.

[0030] Measure 4L of deionized water and place it in a beaker. Add 64g of sucrose, 936g of disodium hydrogen phosphate, and 9.4g of sodium vanadate, stir to dissolve, then add 359g of iron oxide and mix evenly. Add it to a high-gravity reactor, rotate at 30,000rpm, react at 100°C for 1h, then spray dry and calcine at 400°C under a nitrogen atmosphere for 6h to obtain a precursor. Then, mix the precursor with 0.5g of potassium tartrate, 64g of sucrose, and 2L of deionized water, adjust the pH to 2.5, ball mill to a D50 of 0.84um, control the solution temperature to 65°C, then spray dry, and calcine at 500°C for 12h to obtain a structure-modified sodium ion battery positive electrode material - carbon-coated sodium iron pyrophosphate, which is placed in a desiccator for later use.

[0031] Assembly and testing of button cells.

[0032] The positive electrode active material, acetylene black, and binder are evenly mixed with a solvent in a weight ratio of 8:1:1 to prepare a positive electrode slurry, which is then evenly coated on an aluminum foil. After drying, roller pressing, and slicing, a positive electrode sheet is obtained. A metallic sodium sheet is then used as the negative electrode, and a glass fiber membrane is used as the separator. The positive electrode sheet, negative electrode sheet, and separator are placed in a button battery case, and an electrolyte is injected, wherein the electrolyte NaPF6 concentration is 1M and the solvents are EC, DEC, and FEC (vol=9:9:2). After pressing, a sodium ion button half-cell is obtained and tested after being placed for 12 hours.

[0033] The sample has a specific capacity of 93 mAh / g, a carbon content of 2.4%, and a compacted density of 2.0 g / cm 3 , specific surface area 10.9m 2 / g, powder conductivity 2.3×10 -2 S / cm.

[0034] Example 2.

[0035] 4L of deionized water was measured and placed in a beaker. 64g of sucrose, 936g of disodium hydrogen phosphate, and 4.7g of sodium vanadate were added and stirred to dissolve. 359g of iron oxide was then added and mixed evenly. The mixture was added to a high-gravity reactor at a speed of 30,000rpm and reacted at 100°C for 1h. The mixture was then spray-dried and calcined at 400°C under a nitrogen atmosphere for 6h to obtain a precursor. The precursor was then mixed with 0.5g of sodium ethylenediaminetetraacetic acid, 64g of sucrose, and 2L of deionized water. The pH was adjusted to 2.5, and the mixture was ball-milled to a D50 of 0.88um. The solution temperature was controlled at 65°C, and the mixture was spray-dried and calcined at 500°C for 12h to obtain a structure-modified sodium ion battery positive electrode material - carbon-coated sodium iron pyrophosphate.

[0036] The sample has a specific capacity of 89 mAh / g, a carbon content of 2.3%, and a compacted density of 2.1 g / cm 3 , specific surface area 8.7m2 / g, powder conductivity 3.7×10 -3 S / cm. In addition, Figure 2 It can be seen from the X-ray diffraction pattern that the composition of the structure-modified sodium-ion battery positive electrode material is in line with expectations.

[0037] Example 3.

[0038] 4L of deionized water was measured and placed in a beaker. 64g of sucrose, 936g of disodium hydrogen phosphate, and 9.4g of sodium manganate were added and stirred to dissolve. 359g of iron oxide was then added and mixed evenly. The mixture was added to a high-gravity reactor at a speed of 25,000rpm and reacted at 80°C for 1h. The mixture was then spray-dried and calcined at 400°C under a nitrogen atmosphere for 6h to obtain a precursor. The precursor was then mixed with 1.0g of sodium citrate, 64g of sucrose, and 2L of deionized water. The pH was adjusted to 4.0, and the mixture was ball-milled to a D50 of 0.65um. The solution temperature was controlled at 65°C, and the mixture was spray-dried and calcined at 500°C for 12h to obtain a structure-modified sodium ion battery positive electrode material - carbon-coated sodium iron pyrophosphate.

[0039] The sample has a specific capacity of 91 mAh / g, a carbon content of 2.5%, and a compacted density of 2.1 g / cm 3 , specific surface area 14.7m 2 / g, powder conductivity 8.6×10 -3 S / cm.

[0040] Example 4.

[0041] Measure 4L of deionized water and place it in a beaker. Add 64g of sucrose, 936g of disodium hydrogen phosphate, and 4.7g of sodium manganate, stir to dissolve, then add 359g of iron oxide and mix evenly. Add it to a high-gravity reactor, rotate at 35000rpm, react at 90℃ for 1h, spray dry, and calcine at 400℃ for 6h under a nitrogen atmosphere to obtain a precursor. Then, mix the precursor with 1.0g of sodium citrate, 64g of sucrose, and 2L of deionized water, adjust the pH to 3.5, ball mill to D50 of 0.65um, control the solution temperature to 65℃, then spray dry, and calcine at 500℃ for 12h to obtain a structure-modified sodium ion battery positive electrode material - carbon-coated sodium iron pyrophosphate.

[0042] The sample has a specific capacity of 88 mAh / g, a carbon content of 2.4%, and a compacted density of 2.0 g / cm 3 , specific surface area 14.7m 2 / g, powder conductivity 2.9×10 -3 S / cm.

[0043] Example 5.

[0044] Measure 4L of deionized water and place it in a beaker. Add 64g of sucrose, 936g of disodium hydrogen phosphate, and 9.4g of sodium titanate, stir to dissolve, then add 359g of iron oxide and mix evenly. Add it to a high-gravity reactor, rotate at 35000rpm, react at 100℃ for 1h, then spray dry and calcine at 400℃ under a nitrogen atmosphere for 6h to obtain a precursor. The precursor is then mixed with 0.5g of potassium tartrate, 64g of sucrose, and 2L of deionized water, the pH is adjusted to 4.0, ball milled to a D50 of 0.91um, the solution temperature is controlled at 65℃, then spray dried, and calcined at 500℃ for 12h to obtain a structure-modified sodium ion battery positive electrode material - carbon-coated sodium iron pyrophosphate.

[0045] The sample has a specific capacity of 90 mAh / g, a carbon content of 2.2%, and a compacted density of 2.1 g / cm 3 , specific surface area 9.5m 2 / g, powder conductivity 1.4×10 -2 S / cm.

[0046] Comparative Example 1.

[0047] 4L of deionized water was measured and placed in a beaker. 64g of sucrose and 936g of disodium hydrogen phosphate were added and stirred to dissolve. 359g of iron oxide was then added and mixed evenly. The mixture was sand-milled to a D50 of 0.41μm, spray-dried, and calcined at 400°C under a nitrogen atmosphere for 6h to obtain a precursor. The precursor, 64g of sucrose, and 2L of deionized water were then ball-milled to a D50 of 0.72μm. The solution temperature was controlled at 65°C, spray-dried, and calcined at 500°C for 12h to obtain a structure-modified sodium ion battery cathode material - carbon-coated sodium iron pyrophosphate.

[0048] The sample has a specific capacity of 80 mAh / g, a carbon content of 2.2%, and a compacted density of 2.1 g / cm 3 , specific surface area 11.7m 2 / g, powder conductivity 5.6×10 -4 S / cm.

[0049] Comparative Example 2 (adding a structure modifier, not adding a chelating agent, and not using a supergravity reactor).

[0050] 4L of deionized water was measured and placed in a beaker. 64g of sucrose, 936g of disodium hydrogen phosphate, and 9.4g of sodium vanadate were added and stirred to dissolve. 359g of iron oxide was then added and mixed evenly. The mixture was sand-milled in a sand mill, spray-dried, and calcined at 400°C under a nitrogen atmosphere for 6h to obtain a precursor. The precursor, 64g of sucrose, and 2L of deionized water were then ball-milled to a D50 of 0.72μm. The solution temperature was controlled at 65°C, spray-dried, and calcined at 500°C for 12h to obtain a structure-modified sodium ion battery cathode material - carbon-coated sodium iron pyrophosphate.

[0051] The sample has a specific capacity of 84 mAh / g, a carbon content of 2.3%, and a compacted density of 2.2 g / cm 3 , specific surface area 12.4m 2 / g, powder conductivity 7.7×10 -4 S / cm.

[0052] Comparative Example 3 (addition of a structure modifier and a chelating agent, without using a supergravity reactor).

[0053] 4L of deionized water was measured and placed in a beaker. 64g of sucrose, 936g of disodium hydrogen phosphate, and 9.4g of sodium vanadate were added and stirred to dissolve. 359g of iron oxide was then added and mixed evenly. The mixture was sand-milled to a D50 of 0.41μm, spray-dried, and calcined at 400°C under a nitrogen atmosphere for 6h to obtain a precursor. The precursor, 0.5g of potassium tartrate, and 64g of sucrose were then mixed with 2L of deionized water, the pH was adjusted to 2.5, and ball-milled to a D50 of 0.72μm. The solution temperature was controlled at 65°C, spray-dried, and calcined at 500°C for 12h to obtain a structure-modified sodium ion battery positive electrode material - carbon-coated sodium iron pyrophosphate.

[0054] The sample has a specific capacity of 82 mAh / g, a carbon content of 2.2%, and a compacted density of 2.1 g / cm 3 , specific surface area 14.5m 2 / g, powder conductivity 1.2×10 -3 S / cm.

[0055] The sodium ion battery positive electrode materials prepared in Examples 1 to 5 and the sodium ion battery positive electrode materials obtained in Comparative Examples 1 to 3 were respectively subjected to electrical performance tests. The test results are shown in Table 1 below.

[0056] Table 1

[0057]

[0058] As shown in Table 1, the conductivity and 0.1C specific capacity of the structurally modified sodium ion battery positive electrode material prepared by the method provided by the present invention are significantly improved.

[0059] The positive electrode materials of sodium ion batteries of Example 1 and Comparative Examples 1 to 3 were tested by electron microscope respectively, and the results were shown in Table 1. Figure 1 、 Figures 4 to 6 Comparative Example 1 differs from Example 1 in that no structural modification is performed in Comparative Example 1; Comparative Example 2 differs from Example 1 in that a structural modifier is added in Comparative Example 2, but no chelate is added, and no high-gravity reactor is used. Comparative Example 3 differs from Example 1 in that a structural modifier and a chelate are added in Comparative Example 3, but no high-gravity reactor is used.

[0060] from Figure 1 and Figure 4 From the comparison, it can be seen that the particle size of the sodium ion battery positive electrode material after structural modification is smaller and the particles are more uniform.

[0061] from Figure 1 and Figure 5 The comparison, Figure 1 and Figure 6 From the comparison, it can be seen that the structure-modified sodium-ion battery positive electrode material obtained by using a high-speed ultra-gravity reactor has a smaller particle size and more uniform particles.

[0062] The applicant states that the present invention is intended to illustrate the detailed methods of the present invention through the above-described embodiments, but the present invention is not limited to the above-described detailed methods, that is, it does not mean that the present invention must rely on the above-described detailed methods in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for various raw materials in the products of the present invention, addition of auxiliary ingredients, and selection of specific methods, etc., are all within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a structurally modified sodium ion battery cathode material, characterized in that: The steps include: S1. Mix a sodium source, an iron source, a phosphorus source, a first carbon source, a structure modifier, and deionized water, add the mixture to a high-gravity reactor rotating at a speed of 25,000 to 35,000 rpm, react at a temperature of 80 to 100° C. for 1 to 2 hours, dry, and then calcine at 400 to 650° C. under an inert gas atmosphere for 6 to 12 hours to obtain a precursor, wherein the structure modifier is at least one of sodium vanadate, sodium titanate, sodium manganate, sodium cobaltate, sodium chromate, metatitanic acid, magnesium oxide, copper oxide, zinc oxide, and yttrium oxide; S2. Mix the precursor, the second carbon source and the chelate solution, adjust the pH to 2.5-4.0, grind at a temperature of 60-90° C. until D50 is less than 0.95 μm, spray dry, and calcine at 400-650° C. under an inert gas atmosphere for 8-12 hours to obtain the structure-modified sodium ion battery positive electrode material.

2. The preparation method according to claim 1, characterized in that In step S1, the molar number of sodium element in the sodium source is 2 to 3 times the molar number of iron element in the iron source; and the added amount of the structural modifier is 0.1% to 10% of the mass of the phosphorus source.

3. The preparation method according to claim 2, characterized in that The ratio of the molar number of phosphorus in the phosphorus source to the molar number of iron in the iron source is 1.4-2.

4. The preparation method according to claim 3, characterized in that The sodium source is at least one of disodium hydrogen phosphate, sodium carbonate, sodium bicarbonate, sodium hydroxide, and sodium nitrate; the iron source is at least one of ferrous oxalate, ferrous acetate, ferrous citrate, ferrous lactate, and ferric oxide; and the phosphorus source is at least one of disodium hydrogen phosphate, pyrophosphoric acid, sodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, phosphoric acid, and sodium phosphate.

5. The preparation method according to claim 1, characterized in that The chelate in the chelate solution is a complex formed by a metal ion selected from aluminum, copper, silver, nickel, iron, platinum, potassium and cobalt and an ion selected from ethylenediaminetetraacetic acid, citric acid, tartaric acid, tripolyphosphoric acid, hexametaphosphoric acid, aminotriacetic acid and o-phenanthroline.

6. The preparation method according to claim 5, characterized in that The added amount of the chelate is 0.1% to 1% of the mass of the precursor.

7. The preparation method according to claim 6, characterized in that The first carbon source and the second carbon source are the same substance or different substances, and the first carbon source and the second carbon source are both selected from at least one of glucose, sucrose, xylitol, polyvinyl alcohol, starch, and cellulose.

8. The preparation method according to claim 7, characterized in that The total mass of the first carbon source and the second carbon source accounts for 4% to 9% of the total mass of the sodium source, the iron source, the phosphorus source, the first carbon source, and the second carbon source.

9. The preparation method according to claim 8, characterized in that The first carbon source accounts for 50% to 80% of the total mass of the first carbon source and the second carbon source.

10. A structurally modified sodium ion battery cathode material, characterized in that: The structure-modified sodium ion battery positive electrode material is prepared by the preparation method according to any one of claims 1 to 9, and the powder conductivity of the structure-modified sodium ion battery positive electrode material is greater than 7.0×10 -3 S / cm.

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