A sodium cathode composite material and preparation method thereof

Abstract

The invention discloses a sodium cathode composite material and a preparation method thereof. The sodium cathode composite material comprises a FeF3 matrix and sodium manganate loaded thereon; the molar ratio of the sodium manganate to the FeF3 matrix is ​​(1-10):100; the molecular formula of the sodium manganate is Na x MnO2, 0.5≤x≤1. The preparation method comprises the following steps: (1) dispersing a manganese salt and graphene in a solvent to obtain a solution A; dissolving an organic ligand in a solvent to obtain a solution B; reacting solution B and solution A to obtain Mn-MOF; (2) dissolving an iron salt and a fluorine source in a solvent to obtain an iron salt solution and a fluorine source solution, respectively, and adding the fluorine source solution to the iron salt solution to react for a certain period of time to obtain a solid; (3) mixing the solid, Mn-MOF and a sodium source and sintering at a high temperature. The sodium-based positive electrode composite material of the present invention forms an interface heterogeneous structure and a built-in electric field through a unique structural design, which can improve the kinetic properties of the material; the preparation process of the present invention is simple, the process is short, the raw materials are easily available, the preparation process does not contain toxic and harmful substances, and is suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to the field of sodium ion battery positive electrode materials, and in particular to a high-capacity sodium battery positive electrode composite material, a preparation method thereof, and applications thereof. Background Art

[0002] Lithium-ion batteries have become an irreplaceable and superior energy storage device due to their unparalleled advantages, including high energy density, high output voltage, long service life, compact size, light weight, long cycle life, low self-discharge rate, no memory effect, and environmental friendliness. As the application range of lithium-ion batteries continues to expand, the cost of the metals used to produce them is also increasing. Exploring lower-cost rechargeable batteries to replace lithium-ion batteries has become a current research hotspot. Sodium-ion batteries, due to their similar energy storage mechanism and lower cost, are the best choice for the next generation of energy storage batteries.

[0003] In lithium-ion batteries, ferric fluoride, as a metal compound capable of achieving conversion reactions, has a high specific capacity and high voltage platform. The ionic radius of sodium ions is similar to that of lithium ions, so reversible conversion of ferric fluoride can also be achieved. However, the larger radius of sodium ions than lithium ions will cause irreversible damage to the structure of ferric fluoride. Therefore, in order to successfully apply ferric fluoride materials in sodium-ion batteries, it is necessary to improve the structural stability and conductivity of the material. Summary of the Invention

[0004] The present invention provides a sodium battery positive electrode composite material and a preparation method thereof, which are used to solve the technical problem that the existing ferric fluoride material is not suitable for sodium battery positive electrodes.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A sodium cathode composite material comprises a FeF3 matrix and sodium manganate supported on the FeF3 matrix; the molar ratio of the sodium manganate to the FeF3 matrix is ​​(1-10):100; the molecular formula of the sodium manganate is Na x MnO2, wherein x is in the range of 0.5≤x≤1.

[0007] The design idea of ​​the above technical solution is that by loading sodium manganate composite on FeF3 matrix, due to the difference in band gap width between FeF3 and sodium manganate materials, a heterojunction structure is generated at the composite interface of sodium manganate and FeF3. The heterojunction structure has a specific electric field direction, that is, a built-in electric field, which has a certain acceleration effect on the electrons and ions diffusing in the bulk phase, thereby improving the kinetic properties of the material, so that the sodium-based positive electrode composite material of this technical solution can effectively enhance the electrochemical performance of sodium-ion batteries.

[0008] Based on the same technical concept, the present invention also provides a method for preparing the sodium cathode composite material as described above, comprising the following steps:

[0009] (1) dispersing a manganese salt and graphene in a solvent to obtain a solution A; dissolving an organic ligand in a solvent to obtain a solution B; adding the solution B to the solution A to react, and separating to obtain a Mn-MOF material;

[0010] (2) dissolving an iron salt in a solvent to obtain an iron salt solution, dissolving a fluorine source in a solvent to obtain a fluorine source solution, adding the fluorine source solution to the iron salt solution, reacting in a water bath for a certain period of time, and separating to obtain a solid;

[0011] (3) The solid material, Mn-MOF material and sodium source are subjected to ball milling and mixing treatment, and then sintered at high temperature to obtain FeF3 composite sodium manganate material.

[0012] The design idea of ​​the above technical solution is to first generate graphene-coated Mn-MOF material through the reaction between manganese salt, graphene and organic ligand, providing a base template for the subsequent formation of porous material; at the same time, FeF3 is directly prepared by the co-precipitation reaction of iron salt and fluorine source; then through a high-temperature sintering process, FeF3 material is mixed with Mn-MOF material and sodium source. After a large amount of FeF3 material is evenly mixed, Mn-MOF material and sodium source are evenly distributed on the surface. After high-temperature sintering, the Mn-MOF material undergoes high-temperature decomposition and chemically bonds with the sodium source to form a porous sodium manganate coating layer, which is compounded on the surface of the FeF3 material, and finally a sodium battery positive electrode composite material with a specific morphology is obtained.

[0013] As a further preferred embodiment of the above technical solution, the molar ratio of the manganese salt, graphene, and organic ligand in step (1) is 1: (0.01-0.08): (100-300). The metal ions and organic ligands of the MOF material synthesized within this range can be completely complexed; if there are more organic ligands, MOF materials can also be formed, but a large amount of excess organic ligands will cause a waste of resources. If there are too many metal ions, the complexation may be incomplete. The significance of adding graphene is mainly to improve the conductivity of the surface layer and to provide a certain template support for the MOF material.

[0014] As a further preferred embodiment of the above technical solution, the manganese salt comprises at least one of manganese acetate, manganese oxalate, manganese nitrate, and manganese sulfate, with manganese acetate and manganese oxalate being more preferred. These manganese salts themselves possess a certain chelating effect, which can promote the formation of MOFs. The concentration of solution A is 0.01 to 0.1 mol / L. The organic ligand comprises at least one of 2-methylimidazole, trimesic acid, terephthalic acid, and imidazole, and the concentration of solution B is 0.5 to 2 mol / L. If the solution concentration is too low, MOFs will not form easily or the formed precipitate will be small and difficult to separate. If the solution concentration is too high, the MOFs will form too quickly and will easily agglomerate, ultimately affecting the coating effect.

[0015] As a further preferred embodiment of the above technical solution, the reaction time of solution A and solution B in step (1) is 0.5 to 6 hours.

[0016] As a further preferred embodiment of the above technical solution, the molar ratio of the iron salt to the fluorine source in step (2) is 1:(20-50). During the reaction, it is necessary to ensure that there is an excess of fluorine source in the system to promote the formation of ferric fluoride. The ratio within the above range can ensure the smooth formation of ferric fluoride.

[0017] As a further preferred embodiment of the above technical solution, the fluorine source includes at least one of HF, NH4F, and 1-butyl-3-methylimidazolium tetrafluoroborate, and the solubility of the fluorine source is 5 to 25 mol / L; the iron salt includes at least one of ferric chloride, ferric nitrate, and ferric sulfate, and the concentration of the iron salt solution is 0.2 to 2 mol / L.

[0018] As a further preferred embodiment of the above technical solution, the reaction temperature of the fluorine source solution and the iron salt solution is 60-100° C., and the reaction time is 0.5-6 h.

[0019] As a further preferred embodiment of the above technical solution, the molar ratio of the solid matter, the Mn-MOF material and the sodium element in the sodium source in step (3) is (10-100):1:1.05.

[0020] As a further preferred embodiment of the above technical solution, the sodium source in step (3) is a sodium salt or sodium oxide, and the sodium salt includes at least one of sodium carbonate, sodium acetate and sodium oxalate.

[0021] As a further preferred embodiment of the above technical solution, the high-temperature sintering temperature in step (3) is 700-1000° C., and the sintering time is 6-24 hours.

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] (1) The sodium cathode composite material of the present invention has a unique structural design, with an FeF3 structure inside the material and a sodium manganate structure on the outside. An interface heterogeneous structure is formed between the inner and outer layers, and a built-in electric field is also formed, which can further improve the kinetic properties of the material, such as the ion diffusion rate;

[0024] (2) The present invention synthesizes Mn-MOF by a room temperature method, composites it on the surface of the main material FeF3, and directly prepares a sodium cathode material with good performance through further sodium treatment. The preparation process is simple, the process is short, the raw materials are easily available, no toxic or harmful substances are produced during the preparation process, and large-scale production is easy to achieve. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the SEM image of the sodium-ion positive electrode composite material of Example 1. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below with reference to specific embodiments.

[0027] Example 1

[0028] The SEM image of the sodium cathode composite material of this embodiment is as follows: Figure 1 As shown, it includes a FeF3 matrix and sodium manganate loaded on the FeF3 matrix; the molar ratio of sodium manganate to FeF3 matrix is ​​5:100; the molecular formula of the sodium manganate is Na 0.67 MnO2.

[0029] The sodium cathode composite material of this embodiment is prepared by the following method:

[0030] (1) 1 mmol of Mn(NO3)2·6H2O and 10 mg of graphene were dispersed in 50 mL of methanol solution to obtain solution A; 0.25 mol of 2-methylimidazole was dissolved in 300 mL of methanol solution to obtain solution B, which was slowly added dropwise to solution A to carry out complexation reaction at room temperature. After the reaction lasted for 1 hour, the mixed solution was centrifuged, washed, and dried to obtain the Mn-MOF material;

[0031] (2) Dissolve 0.02 mol FeCl3 in 50 ml deionized water to obtain an iron salt solution, slowly drop 20 ml of 40% HF acid (fluorine source solution) into the iron salt solution, react in a 100°C water bath for 1 hour, then centrifuge, wash, and dry to obtain a solid;

[0032] (3) After ball milling, 0.02 mol of solid material, 1 mmol of Mn-MOF material and 0.525 mmol of Na2CO3 were mixed and sintered at high temperature (sintering temperature was 700 °C, sintering time was 24 h) to obtain the sodium cathode composite material (FeF3 composite Na0.67 MnO2 material).

[0033] With the above FeF3 composite Na 0.67 MnO2 material is the active material of the positive electrode material and is mixed with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. N-methylpyrrolidone (NMP) is used as the solvent and the mixture is stirred in a small beaker at a speed of 800r / min for 2 hours to obtain a slurry. The slurry is coated on the current collector aluminum foil using an automatic coating machine, placed flat on tempered glass and transferred to a vacuum drying oven at 85°C for 4 hours. The sheet is punched into a 12mm diameter electrode and then dried at 105°C in a vacuum drying oven for 4 hours. It is placed in a glove box filled with argon atmosphere with a moisture and oxygen content of less than 0.1ppm for 4 hours to reduce the moisture adsorbed by the electrode during the transfer process. It is then assembled into a CR2032 button battery in the glove box. The metallic sodium is rolled into thin sheets and punched into 14mm round sodium sheets to serve as the negative electrode. A 1mol / L NaClO4 solution is used as the electrolyte, and a glass fiber membrane with a diameter of 16mm is used as the diaphragm.

[0034] After the battery was assembled and aged for 12 hours, charge and discharge tests were performed at different potentials. The discharge capacity of the calcined sample was 125.7 mA hg after 100 cycles at a voltage of 2-4.2 V and a current density of 1 C. -1 , the capacity retention rate is 87.8%.

[0035] Comparative Example 1

[0036] The sodium cathode material of this comparative example was prepared by the following method:

[0037] Dissolve 0.02 mol FeCl3 in 50 ml of deionized water. Slowly drip 20 ml of 40% HF acid into the iron salt solution. After reacting in a water bath for 1 hour, centrifuge, wash, and dry it. Then, sinter it at 300°C for 6 hours and remove the water to obtain the FeF3 positive electrode material.

[0038] FeF3 was used as the active material for the positive electrode. It was mixed with acetylene black (AB), a conductive agent, and polyvinylidene fluoride (PVDF), a binder, in a mass ratio of 8:1:1. N-methylpyrrolidone (NMP) was used as the solvent. The mixture was stirred in a small beaker at 800 rpm for 2 hours to produce a slurry. The slurry was coated onto aluminum foil, a current collector, using an automatic coater. The slurry was then placed flat on tempered glass and dried in a vacuum drying oven at 85°C for 4 hours. Electrodes with a diameter of 12 mm were punched out and dried in a vacuum drying oven at 105°C for 4 hours. The electrodes were then placed in an argon-filled glove box with a moisture and oxygen content below 0.1 ppm for 4 hours to reduce moisture adsorption during transfer. The cells were then assembled into CR2032 button cells in the glove box. The metallic sodium is rolled into thin sheets and punched into 14mm round sodium sheets to serve as the negative electrode. A 1mol / L NaClO4 solution is used as the electrolyte, and a glass fiber membrane with a diameter of 16mm is used as the diaphragm.

[0039] After the battery was assembled and aged for 12 hours, charge and discharge tests were performed at different potentials. The discharge capacity of the calcined sample was 69.3 mA hg after 100 cycles at a voltage of 2-4.2 V and a current density of 1 C. -1 , the capacity retention rate is 53.5%.

[0040] Example 2

[0041] The sodium cathode composite material of this embodiment includes a FeF3 matrix and sodium manganate loaded on the FeF3 matrix; the molar ratio of sodium manganate to FeF3 matrix is ​​5:100; the molecular formula of the sodium manganate is Na 0.67 MnO2.

[0042] The sodium cathode composite material of this embodiment is prepared by the following method:

[0043] (1) 1 mmol of Mn(NO3)2·6H2O and 10 mg of graphene were dispersed in 50 mL of methanol solution to obtain solution A; 0.25 mol of 2-methylimidazole was dissolved in 300 mL of methanol solution to obtain solution B, which was slowly added dropwise to solution A to carry out complexation reaction at room temperature. After the reaction lasted for 1 hour, the mixed solution was centrifuged, washed, and dried to obtain the Mn-MOF material;

[0044] (2) Dissolve 0.02 mol FeCl3 in 50 ml deionized water to obtain an iron salt solution, and dissolve 0.45 mol NH4F in 20 mL deionized water to obtain a fluorine source solution. Slowly drop the fluorine source solution into the iron salt solution, react in a water bath at 60°C for 1 hour, then centrifuge, wash, and dry to obtain a solid;

[0045] (3) After 0.02 mol of solid material was mixed with 1 mmol of Mn-MOF material and 0.525 mmol of Na2CO3 by ball milling, the sodium cathode composite material (FeF3 composite Na2CO3) was obtained after high temperature sintering (sintering temperature was 1000℃, sintering time was 6h). 0.67 MnO2 material).

[0046] With the above FeF3 composite Na 0.67 MnO2 material is the active material of the positive electrode material and is mixed with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. N-methylpyrrolidone (NMP) is used as the solvent and the mixture is stirred in a small beaker at a speed of 800r / min for 2 hours to obtain a slurry. The slurry is coated on the current collector aluminum foil using an automatic coating machine, placed flat on tempered glass and transferred to a vacuum drying oven at 85°C for 4 hours. The sheet is punched into a 12mm diameter electrode and then dried at 105°C in a vacuum drying oven for 4 hours. It is placed in a glove box filled with argon atmosphere with a moisture and oxygen content of less than 0.1ppm for 4 hours to reduce the moisture adsorbed by the electrode during the transfer process. It is then assembled into a CR2032 button battery in the glove box. The metallic sodium is rolled into thin sheets and punched into 14mm round sodium sheets to serve as the negative electrode. A 1mol / L NaClO4 solution is used as the electrolyte, and a glass fiber membrane with a diameter of 16mm is used as the diaphragm.

[0047] After the battery was assembled and aged for 12 hours, charge and discharge tests were performed at different potentials. The discharge capacity of the calcined sample was 118.4 mA h g after 100 cycles at a voltage of 2-4.2 V and a current density of 1 C. -1 , the capacity retention rate is 82.6%.

[0048] Example 3

[0049] The SEM image of the sodium cathode composite material of this embodiment is as follows: Figure 1 As shown, it includes a FeF3 matrix and sodium manganate loaded on the FeF3 matrix; the molar ratio of sodium manganate to FeF3 matrix is ​​2.5:100; the molecular formula of the sodium manganate is Na 0.67 MnO2.

[0050] The sodium cathode composite material of this embodiment is prepared by the following method:

[0051] (1) 1 mmol of Mn(NO3)2·6H2O and 10 mg of graphene were dispersed in 50 mL of methanol solution to obtain solution A; 0.25 mol of 2-methylimidazole was dissolved in 300 mL of methanol solution to obtain solution B, which was slowly added dropwise to solution A to carry out complexation reaction at room temperature. After the reaction lasted for 1 hour, the mixed solution was centrifuged, washed, and dried to obtain the Mn-MOF material;

[0052] (2) Dissolve 0.02 mol FeCl3 in 50 ml deionized water to obtain an iron salt solution, slowly drop 20 ml of 40% HF acid (fluorine source solution) into the iron salt solution, react in an 80°C water bath for 1 hour, then centrifuge, wash, and dry to obtain a solid;

[0053] (3) After ball milling, 0.02 mol of solid material, 0.5 mmol of Mn-MOF material and 0.26 mmol of Na2CO3 were mixed and sintered at high temperature (sintering temperature was 900 °C and sintering time was 12 h) to obtain the sodium cathode composite material (FeF3 composite Na 0.67 MnO2) materials.

[0054] With the above FeF3 composite Na 0.67 MnO2 material is the active material of the positive electrode material and is mixed with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. N-methylpyrrolidone (NMP) is used as the solvent and the mixture is stirred in a small beaker at a speed of 800r / min for 2 hours to obtain a slurry. The slurry is coated on the current collector aluminum foil using an automatic coating machine, placed flat on tempered glass and transferred to a vacuum drying oven at 85°C for 4 hours. The sheet is punched into a 12mm diameter electrode and then dried at 105°C in a vacuum drying oven for 4 hours. It is placed in a glove box filled with argon atmosphere with a moisture and oxygen content of less than 0.1ppm for 4 hours to reduce the moisture adsorbed by the electrode during the transfer process. It is then assembled into a CR2032 button battery in the glove box. The metallic sodium is rolled into thin sheets and punched into 14mm round sodium sheets to serve as the negative electrode. A 1mol / L NaClO4 solution is used as the electrolyte, and a glass fiber membrane with a diameter of 16mm is used as the diaphragm.

[0055] After the battery was assembled and aged for 12 hours, charge and discharge tests were performed at different potentials. The discharge capacity of the calcined sample after 100 cycles at a voltage of 2-4.2V and a current density of 1C was 109.7mA hg -1 , the capacity retention rate is 76.3%.

[0056] Example 4

[0057] The SEM image of the sodium cathode composite material of this embodiment is as follows: Figure 1As shown, it includes a FeF3 matrix and sodium manganate loaded on the FeF3 matrix; the molar ratio of sodium manganate to FeF3 matrix is ​​7.5:100; the molecular formula of the sodium manganate is Na 0.67 MnO2.

[0058] The sodium cathode composite material of this embodiment is prepared by the following method:

[0059] (1) 1.5 mmol Mn(NO3)2·6H2O and 15 mg graphene were dispersed in 75 mL methanol solution to obtain solution A; 0.37 mol 2-methylimidazole was dissolved in 400 mL methanol solution to obtain solution B, which was slowly added dropwise to solution A to carry out complexation reaction at room temperature. After the reaction lasted for 1 hour, the mixed solution was centrifuged, washed, and dried to obtain the Mn-MOF material;

[0060] (2) Dissolve 0.02 mol FeCl3 in 50 ml deionized water to obtain an iron salt solution, slowly drop 20 ml of 40% HF acid (fluorine source solution) into the iron salt solution, react in a water bath at 100°C for 1 hour, then centrifuge, wash, and dry to obtain a solid;

[0061] (3) After ball milling 0.02 mol of solid, 1.5 mmol of Mn-MOF material and 0.787 mmol of Na2CO3, and sintering at high temperature, the sodium cathode composite material (FeF3 composite Na 0.67 MnO2 material).

[0062] With the above FeF3 composite Na 0.67 MnO2 material is the active material of the positive electrode material and is mixed with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. N-methylpyrrolidone (NMP) is used as the solvent and the mixture is stirred in a small beaker at a speed of 800r / min for 2 hours to obtain a slurry. The slurry is coated on the current collector aluminum foil using an automatic coating machine, placed flat on tempered glass and transferred to a vacuum drying oven at 85°C for 4 hours. The sheet is punched into a 12mm diameter electrode and then dried at 105°C in a vacuum drying oven for 4 hours. It is placed in a glove box filled with argon atmosphere with a moisture and oxygen content of less than 0.1ppm for 4 hours to reduce the moisture adsorbed by the electrode during the transfer process. It is then assembled into a CR2032 button battery in the glove box. The metallic sodium is rolled into thin sheets and punched into 14mm round sodium sheets to serve as the negative electrode. A 1mol / L NaClO4 solution is used as the electrolyte, and a glass fiber membrane with a diameter of 16mm is used as the diaphragm.

[0063] After the battery was assembled and aged for 12 hours, charge and discharge tests were performed at different potentials. The discharge capacity of the calcined sample was 115.8 mA hg after 100 cycles at a voltage of 2-4.2 V and a current density of 1 C. -1 , the capacity retention rate is 80.6%.

[0064] The above is only a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiment. For those skilled in the art, improvements and modifications obtained without departing from the technical concept of the present invention should also be considered as the scope of protection of the present invention.

Claims

1. A method for preparing a sodium cathode composite material, characterized in that: The sodium cathode composite material comprises a FeF3 matrix and sodium manganate compositely loaded on the FeF3 matrix; the molar ratio of the sodium manganate to the FeF3 matrix is ​​(1-10):100; the molecular formula of the sodium manganate is Na x MnO2, wherein the range of x is 0.5≤x≤1; the preparation method comprises the following steps: (1) dispersing a manganese salt and graphene in a solvent to obtain a solution A; dissolving an organic ligand in a solvent to obtain a solution B; adding the solution B to the solution A to react, and separating to obtain a Mn-MOF material; (2) dissolving an iron salt in a solvent to obtain an iron salt solution, dissolving a fluorine source in a solvent to obtain a fluorine source solution, adding the fluorine source solution to the iron salt solution, heating the reaction for a certain period of time, and separating to obtain a solid; (3) The solid material, Mn-MOF material and sodium source are subjected to ball milling and mixing treatment, and then sintered at high temperature to obtain FeF3 composite sodium manganate material.

2. The method for preparing the sodium-ion cathode composite material according to claim 1, wherein: The molar ratio of the manganese salt, graphene and organic ligand in step (1) is 1: (0.01-0.08): (100-300).

3. The method for preparing the sodium-ion cathode composite material according to claim 2, wherein: The manganese salt includes at least one of manganese acetate, manganese oxalate, manganese nitrate and manganese sulfate; the concentration of solution A is 0.01 to 0.1 mol / L; the organic ligand includes at least one of 2-methylimidazole, trimesic acid, terephthalic acid and imidazole, and the concentration of solution B is 0.5 to 2 mol / L.

4. The method for preparing the sodium-ion cathode composite material according to claim 1, wherein: The reaction time of solution A and solution B in step (1) is 0.5 to 6 hours.

5. The method for preparing the sodium-ion cathode composite material according to claim 1, wherein: The molar ratio of the iron salt to the fluorine source in step (2) is 1:(20-50).

6. The method for preparing the sodium-based cathode composite material according to claim 5, wherein: The fluorine source includes at least one of HF, NH4F, and 1-butyl-3-methylimidazolium tetrafluoroborate, and the solubility of the fluorine source is 5 to 25 mol / L; the iron salt includes at least one of ferric chloride, ferric nitrate, and ferric sulfate, and the concentration of the iron salt solution is 0.2 to 2 mol / L.

7. The method for preparing the sodium-ion cathode composite material according to claim 1, wherein: The reaction temperature of the fluorine source solution and the iron salt solution is 60-100° C., and the reaction time is 0.5-6 h.

8. The method for preparing the sodium battery cathode composite material according to any one of claims 1 to 7, characterized in that: The molar ratio of the solid matter, the Mn-MOF material and the sodium element in the sodium source in step (3) is (10-100):1:1.

05.

9. The method for preparing the sodium battery cathode composite material according to any one of claims 1 to 7, characterized in that: The sodium source in step (3) is sodium salt or sodium oxide, and the sodium salt includes at least one of sodium carbonate, sodium acetate and sodium oxalate.

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