Preparation method and application of sodium ion battery polyanion positive electrode material

Abstract

The invention relates to a preparation method and application of a sodium ion battery polyanion positive electrode material. The preparation method comprises the following steps: adding sodium acetate, manganese acetate, citric acid and tetra-n-butyl titanate into ethanol, and stirring and mixing to obtain a solution 1; adding ammonium dihydrogen phosphate into deionized water, and stirring and mixing to obtain a solution 2; mixing the solution 1 and the solution 2, drying, and calcining at high temperature to obtain a mixture; mixing the mixture, a conductive material and modified graphene oxide, and performing ball milling to obtain an active substance; stirring and mixing an active material, a conductive material, polytetrafluoroethylene and isopropanol, coating the surface of the stainless steel mesh with the mixture, and drying to obtain the polyanion positive electrode material of the sodium-ion battery; the sodium-ion battery is assembled by taking the sodium-ion battery polyanion positive electrode material as a positive electrode, a negative electrode, a diaphragm and electrolyte; the sodium ion battery polyanion positive electrode material prepared by the invention also has excellent specific capacity and rate capability at low temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion batteries, and in particular to a preparation method and application of a polyanion cathode material for sodium ion batteries. Background Art

[0002] Sodium-ion batteries are attracting more and more attention due to their abundant resources, low cost, and electrochemical properties similar to those of lithium-ion batteries. They are smaller in size among various new types of batteries, can reduce structural damage to materials during charging and discharging, and have better cycle performance.

[0003] Chinese patent CN116825981A: discloses a sodium ion battery polyanion cathode material / C composite material and its preparation method, the preparation method includes the steps of preparing precursor powder, controlling the particle size of the precursor powder and secondary coating of the polyanion cathode material.

[0004] Chinese patent CN117712334A: discloses a sodium ion battery polyanion cathode material co-coated with boric acid / carbon, and its preparation method and application, wherein the preparation method comprises the following steps: (1) uniformly mixing a sodium source, a transition metal source, an anion source and a solid carbon source, and drying to obtain a precursor powder; (2) uniformly mixing the precursor powder with boric acid, and sintering in a non-oxidizing atmosphere to obtain a sodium ion battery polyanion cathode material.

[0005] Chinese patent CN117525391A: discloses a sodium ion battery polyanion cathode material and its preparation method. Potassium ions and ruthenium ions are doped simultaneously in a sodium ferric pyrophosphate material, and the sodium ferric pyrophosphate material is coated with carbon.

[0006] The development of sodium ion battery positive electrode materials prepared by the above patents and existing technologies is limited by their defects such as poor conductivity, low energy density and low Coulomb efficiency. Summary of the Invention

[0007] In order to solve the above problems, the present invention provides a preparation method and application of a polyanion cathode material for sodium ion batteries, the operation steps of which are as follows:

[0008] S1: Add 17-22 parts of sodium acetate, 0.1-1 parts of manganese acetate, 8-12 parts of citric acid, and 5-10 parts of tetrabutyl titanate to 30-40 parts of ethanol, and stir to mix thoroughly to obtain Solution 1;

[0009] S2: Add 1-5 parts of ammonium dihydrogen phosphate to 5-10 parts of deionized water, stir and mix to obtain solution 2;

[0010] S3: After mixing solution 1 and solution 2 evenly, drying, calcining at high temperature under an argon atmosphere, and cooling to room temperature to obtain a mixture;

[0011] S4: 26-40 parts of the mixture, 1-5 parts of the conductive material, and 1-5 parts of the modified graphene oxide are mixed and ball-milled to obtain an active material;

[0012] S5: 55-63 parts of active material, 10-18 parts of conductive material, 3-9 parts of polytetrafluoroethylene, and 1-5 parts of isopropyl alcohol are stirred and evenly mixed, and then coated on the surface of a stainless steel mesh and dried to obtain a polyanion cathode material for a sodium ion battery;

[0013] S6: Use the sodium ion battery polyanion positive electrode material as the positive electrode, and assemble it into a sodium ion battery together with the negative electrode, separator, and electrolyte.

[0014] The high-temperature calcination temperature is 550-650° C. and the time is 200-240 minutes.

[0015] The ball-to-material mass ratio of the ball mill is 8-10:1, the rotation speed of the ball mill is 400-500 r / min, and the ball milling time is 200-240 min.

[0016] The conductive material is one of carbon nanotubes, superP, acetylene black, carbon nanohorns, and Ketjen black.

[0017] The negative electrode is metallic sodium.

[0018] The diaphragm is glass fiber.

[0019] The electrolyte is a mixed solution formed by dissolving 1 mol / L sodium perchlorate in ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, and adding 5% by mass fluoroethylene carbonate.

[0020] The preparation method of the modified graphene oxide is:

[0021] T1 composite intermediate synthesis and preliminary reaction: Add 10-15 parts of vinyl polyoxyethylene ether, 5-10 parts of hydrogenated silicone oil, 0.05-0.4 parts of 2-vinyl-5,5-dimethyl-1,3,2-dioxaborane, and 1000-1200 parts of toluene to a reactor by mass and stir evenly. Then add 0.01-0.05 parts of chloroplatinic acid catalyst, raise the temperature to 80-90°C to carry out hydrosilylation reaction, and continue stirring for 4-6 hours;

[0022] T2: Add 110-130 parts of graphene oxide, stir at 85-95°C for 45-75 minutes, and disperse by ultrasound at an ultrasonic power of 80-120 W for 20-40 minutes; allow the intermediate to fully react with the hydroxyl groups on the surface of the graphene oxide, centrifuge, wash, and vacuum dry at 55-65°C for 10-14 hours to obtain modified graphene oxide.

[0023] Reaction mechanism

[0024] Hydrosilylation (T1): A vinyl polyoxyethylene ether and a hydrogenated silicone oil undergo hydrosilylation in the presence of a catalyst, generating a siloxane intermediate containing a polyether segment (e.g., Si-O-PEG structure). 2-Vinyl-5,5-dimethyl-1,3,2-dioxaborane is used as a crosslinker, introducing reactive sites through the boron-oxygen ring structure to enhance the intermediate's binding to graphene oxide.

[0025] Graphene oxide modification (T2): Graphene oxide surface hydroxyl groups (-OH) react with siloxane groups (-Si-O-) in the intermediate via condensation to form covalent bonds (Si-OC). Boron-oxygen rings coordinate with the hydroxyl groups, stabilizing the interface structure. The hydrophilicity of the polyether segments (PEG) improves the dispersibility of graphene oxide in polar solvents while inhibiting its π-π stacking and preventing agglomeration.

[0026] Technical Effects

[0027] The present invention provides a method for preparing a sodium ion battery polyanion cathode material and its application. Compared with the prior art, the present invention has the following significant effects:

[0028] 1. Significantly improve the electronic conductivity of polyanion cathode materials, thereby improving the rate performance of the battery.

[0029] 2. Enhanced the cycle stability of the positive electrode material and extended the service life of the battery.

[0030] 3. The dispersibility and processing performance of graphene oxide are improved, which is conducive to large-scale industrial production. DETAILED DESCRIPTION

[0031] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention object, the following is a detailed description in conjunction with examples and comparative examples:

[0032] Electrochemical performance testing: Conducted on a LANHE battery test system over a voltage range of 1.5-4.2 V. For galvanostatic intermittent titration, the charge / discharge current was 10 mA / g for 10 minutes, followed by a 60-minute relaxation period. Specific capacity was measured at -30°C and 0.2C, and specific capacity retention was measured after 1000 cycles at 1C.

[0033] Example 1

[0034] A preparation method and application of a sodium ion battery polyanion cathode material, the operating steps are:

[0035] S1: Add 17 g of sodium acetate, 0.1 g of manganese acetate, 8 g of citric acid, and 5 g of tetrabutyl titanate to 30 g of ethanol, and stir to mix thoroughly to obtain Solution 1;

[0036] S2: Add 1 g of ammonium dihydrogen phosphate to 5 g of deionized water and stir to obtain solution 2;

[0037] S3: After mixing solution 1 and solution 2 evenly, drying, calcining at high temperature under an argon atmosphere, and cooling to room temperature to obtain a mixture;

[0038] S4: 26 g of the mixture, 1 g of the conductive material, and 1 g of the modified graphene oxide were mixed and ball-milled to obtain an active material;

[0039] S5: 55g of active material, 10g of conductive material, 3g of polytetrafluoroethylene, and 1g of isopropyl alcohol were stirred and mixed uniformly, coated on the surface of a stainless steel mesh, and dried to obtain a polyanion cathode material for a sodium ion battery;

[0040] S6: Use the sodium ion battery polyanion positive electrode material as the positive electrode, and assemble it into a sodium ion battery together with the negative electrode, separator, and electrolyte.

[0041] The high-temperature calcination temperature is 550° C. and the time is 200 minutes.

[0042] The ball-to-material mass ratio of the ball mill is 8:1, the rotation speed of the ball mill is 400 r / min, and the ball milling time is 200 min.

[0043] The conductive material is carbon nanotubes.

[0044] The negative electrode is metallic sodium.

[0045] The diaphragm is glass fiber.

[0046] The electrolyte is a mixed solution formed by dissolving 1 mol / L sodium perchlorate in ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, and adding 5% by mass fluoroethylene carbonate.

[0047] The preparation method of the modified graphene oxide is:

[0048] T1 composite intermediate synthesis and preliminary reaction: 10 g of vinyl polyoxyethylene ether, 5 g of hydrogenated silicone oil, 0.05 g of 2-vinyl-5,5-dimethyl-1,3,2-dioxaborane, and 1000 g of toluene were added to a reactor and stirred evenly. 0.01 g of chloroplatinic acid catalyst was then added, and the temperature was raised to 80°C for a hydrosilylation reaction. Stirring was continued for 4 hours.

[0049] T2: Add 110 g of graphene oxide, stir at 85°C for 45 minutes, and disperse by ultrasound at 80 W for 20 minutes; allow the intermediate to fully react with the hydroxyl groups on the surface of graphene oxide, centrifuge, wash, and vacuum dry at 55°C for 10 hours to obtain modified graphene oxide.

[0050] Example 2

[0051] A preparation method and application of a sodium ion battery polyanion cathode material, the operating steps are:

[0052] S1: Add 18 g of sodium acetate, 0.5 g of manganese acetate, 9 g of citric acid, and 6 g of tetrabutyl titanate to 33 g of ethanol, and stir to mix thoroughly to obtain Solution 1;

[0053] S2: Add 2 g of ammonium dihydrogen phosphate to 6 g of deionized water and stir to obtain solution 2;

[0054] S3: After mixing solution 1 and solution 2 evenly, drying, calcining at high temperature under an argon atmosphere, and cooling to room temperature to obtain a mixture;

[0055] S4: 30 g of the mixture, 2 g of the conductive material, and 2 g of the modified graphene oxide were mixed and ball-milled to obtain an active material;

[0056] S5: 58g of active material, 12g of conductive material, 5g of polytetrafluoroethylene, and 2g of isopropyl alcohol were stirred and mixed uniformly, coated on the surface of a stainless steel mesh, and dried to obtain a sodium ion battery polyanion positive electrode material;

[0057] S6: Use the sodium ion battery polyanion positive electrode material as the positive electrode, and assemble it into a sodium ion battery together with the negative electrode, separator, and electrolyte.

[0058] The high-temperature calcination temperature is 580° C. and the time is 210 minutes.

[0059] The ball-to-material mass ratio of the ball mill is 9:1, the rotation speed of the ball mill is 450 r / min, and the ball milling time is 210 min.

[0060] The conductive material is superP.

[0061] The negative electrode is metallic sodium.

[0062] The diaphragm is glass fiber.

[0063] The electrolyte is a mixed solution formed by dissolving 1 mol / L sodium perchlorate in ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, and adding 5% by mass fluoroethylene carbonate.

[0064] The preparation method of the modified graphene oxide is:

[0065] T1 composite intermediate synthesis and preliminary reaction: 12 g of vinyl polyoxyethylene ether, 6 g of hydrogenated silicone oil, 0.2 g of 2-vinyl-5,5-dimethyl-1,3,2-dioxaborane, and 1050 g of toluene were added to a reactor and stirred evenly. 0.02 g of chloroplatinic acid catalyst was then added, and the temperature was raised to 85°C for a hydrosilylation reaction. Stirring was continued for 5 hours.

[0066] T2: Add 115 g of graphene oxide, stir at 88°C for 55 minutes, and disperse by ultrasound at 90 W for 25 minutes; allow the intermediate to fully react with the hydroxyl groups on the surface of graphene oxide, centrifuge, wash, and vacuum dry at 58°C for 11 hours to obtain modified graphene oxide.

[0067] Example 3

[0068] A preparation method and application of a sodium ion battery polyanion cathode material, the operating steps are:

[0069] S1: Add 20 g of sodium acetate, 0.8 g of manganese acetate, 11 g of citric acid, and 8 g of tetrabutyl titanate to 38 g of ethanol, and stir to mix thoroughly to obtain Solution 1;

[0070] S2: Add 4 g of ammonium dihydrogen phosphate to 8 g of deionized water and stir to obtain solution 2;

[0071] S3: After mixing solution 1 and solution 2 evenly, drying, calcining at high temperature under an argon atmosphere, and cooling to room temperature to obtain a mixture;

[0072] S4: 36 g of the mixture, 4 g of the conductive material, and 4 g of the modified graphene oxide were mixed and ball-milled to obtain an active material;

[0073] S5: 60g of active material, 16g of conductive material, 7g of polytetrafluoroethylene, and 4g of isopropyl alcohol were stirred and mixed uniformly, coated on the surface of a stainless steel mesh, and dried to obtain a polyanion cathode material for a sodium ion battery;

[0074] S6: Use the sodium ion battery polyanion positive electrode material as the positive electrode, and assemble it into a sodium ion battery together with the negative electrode, separator, and electrolyte.

[0075] The high-temperature calcination temperature is 630° C. and the time is 230 minutes.

[0076] The ball-to-material mass ratio of the ball mill is 9:1, the rotation speed of the ball mill is 450 r / min, and the ball milling time is 230 min.

[0077] The conductive material is acetylene black.

[0078] The negative electrode is metallic sodium.

[0079] The diaphragm is glass fiber.

[0080] The electrolyte is a mixed solution formed by dissolving 1 mol / L sodium perchlorate in ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, and adding 5% by mass fluoroethylene carbonate.

[0081] The preparation method of the modified graphene oxide is:

[0082] T1 composite intermediate synthesis and preliminary reaction: 14 g of vinyl polyoxyethylene ether, 8 g of hydrogenated silicone oil, 0.3 g of 2-vinyl-5,5-dimethyl-1,3,2-dioxaborane, and 1150 g of toluene were added to a reactor and stirred evenly. 0.04 g of chloroplatinic acid catalyst was then added, and the temperature was raised to 85°C for a hydrosilylation reaction. Stirring was continued for 5 hours.

[0083] T2: Add 125 g of graphene oxide, stir at 93°C for 65 minutes, and disperse by ultrasound at an ultrasonic power of 110 W for 35 minutes; allow the intermediate to fully react with the hydroxyl groups on the surface of graphene oxide, centrifuge, wash, and vacuum dry at 63°C for 13 hours to obtain modified graphene oxide.

[0084] Example 4

[0085] A preparation method and application of a sodium ion battery polyanion cathode material, the operating steps are:

[0086] S1: Add 22 g of sodium acetate, 1 g of manganese acetate, 12 g of citric acid, and 10 g of tetrabutyl titanate to 40 g of ethanol, and stir to mix well to obtain solution 1;

[0087] S2: Add 5 g of ammonium dihydrogen phosphate to 10 g of deionized water and stir to obtain solution 2;

[0088] S3: After mixing solution 1 and solution 2 evenly, drying, calcining at high temperature under an argon atmosphere, and cooling to room temperature to obtain a mixture;

[0089] S4: 40 g of the mixture, 5 g of the conductive material, and 5 g of the modified graphene oxide were mixed and ball-milled to obtain an active material;

[0090] S5: 63g of active material, 18g of conductive material, 9g of polytetrafluoroethylene, and 5g of isopropyl alcohol were stirred and mixed uniformly, coated on the surface of a stainless steel mesh, and dried to obtain a polyanion cathode material for a sodium ion battery;

[0091] S6: Use the sodium ion battery polyanion positive electrode material as the positive electrode, and assemble it into a sodium ion battery together with the negative electrode, separator, and electrolyte.

[0092] The high-temperature calcination temperature is 650° C. and the time is 240 minutes.

[0093] The ball-to-material mass ratio of the ball mill is 10:1, the rotation speed of the ball mill is 500 r / min, and the ball milling time is 240 min.

[0094] The conductive material is Ketjen black.

[0095] The negative electrode is metallic sodium.

[0096] The diaphragm is glass fiber.

[0097] The electrolyte is a mixed solution formed by dissolving 1 mol / L sodium perchlorate in ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, and adding 5% by mass fluoroethylene carbonate.

[0098] The preparation method of the modified graphene oxide is:

[0099] T1 composite intermediate synthesis and preliminary reaction: 15 g of vinyl polyoxyethylene ether, 10 g of hydrogenated silicone oil, 0.4 g of 2-vinyl-5,5-dimethyl-1,3,2-dioxaborane, and 1200 g of toluene were added to a reactor and stirred evenly. 0.05 g of chloroplatinic acid catalyst was then added, and the temperature was raised to 90°C for a hydrosilylation reaction. Stirring was continued for 6 hours.

[0100] T2: Add 130 g of graphene oxide, stir at 95°C for 75 minutes, and disperse by ultrasound at an ultrasonic power of 120 W for 40 minutes; allow the intermediate to fully react with the hydroxyl groups on the surface of graphene oxide, centrifuge, wash, and vacuum dry at 65°C for 14 hours to obtain modified graphene oxide.

[0101] Comparative Example 1

[0102] The graphene oxide was not modified, and the other steps were the same as in Example 1.

[0103] Comparative Example 2

[0104] No hydrogenated silicone oil was added, and the other steps were the same as in Example 1.

[0105] Comparative Example 3

[0106] The other steps were the same as in Example 1 except that 2-vinyl-5,5-dimethyl-1,3,2-dioxaborolane was not added.

[0107] Specific capacity / mA·h / g Specific capacity retention rate / % Example 1 113.8 91.8 Example 2 115.6 92.6 Example 3 119.3 94.2 Example 4 121.5 94.9 Comparative Example 1 83.7 73.1 Comparative Example 2 96.1 85.2 Comparative Example 3 103.2 86.6

[0108] Through the data analysis of the above examples and comparative examples, the sodium ion battery polyanion positive electrode material prepared by the present invention has excellent specific capacity and rate performance even at low temperatures.

[0109] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A preparation method and application of a polyanion cathode material for sodium ion batteries, the operation steps are as follows: S1: Add 17-22 parts of sodium acetate, 0.1-1 parts of manganese acetate, 8-12 parts of citric acid, and 5-10 parts of tetrabutyl titanate to 30-40 parts of ethanol, and stir to mix thoroughly to obtain Solution 1; S2: Add 1-5 parts of ammonium dihydrogen phosphate to 5-10 parts of deionized water, stir and mix to obtain solution 2; S3: After mixing solution 1 and solution 2 evenly, drying, calcining at high temperature under an argon atmosphere, and cooling to room temperature to obtain a mixture; S4: 26-40 parts of the mixture, 1-5 parts of the conductive material, and 1-5 parts of the modified graphene oxide are mixed and ball-milled to obtain an active material; S5: 55-63 parts of active material, 10-18 parts of conductive material, 3-9 parts of polytetrafluoroethylene, and 1-5 parts of isopropyl alcohol are stirred and evenly mixed, and then coated on the surface of a stainless steel mesh and dried to obtain a polyanion cathode material for a sodium ion battery; S6: Use the sodium ion battery polyanion positive electrode material as the positive electrode, and assemble it into a sodium ion battery together with the negative electrode, separator, and electrolyte.

2. The preparation method and application of a sodium ion battery polyanion cathode material according to claim 1, characterized in that: The high-temperature calcination temperature is 550-650° C. and the time is 200-240 minutes.

3. The preparation method and application of a sodium ion battery polyanion cathode material according to claim 1, characterized in that: The ball-to-material mass ratio of the ball mill is 8-10:1, the rotation speed of the ball mill is 400-500 r / min, and the ball milling time is 200-240 min.

4. The preparation method and application of a sodium ion battery polyanion cathode material according to claim 1, characterized in that: The conductive material is one of carbon nanotubes, superP, acetylene black, carbon nanohorns, and Ketjen black.

5. The preparation method and application of a sodium ion battery polyanion cathode material according to claim 1, characterized in that: The negative electrode is metallic sodium.

6. The preparation method and application of a sodium ion battery polyanion cathode material according to claim 1, characterized in that: The diaphragm is glass fiber.

7. The preparation method and application of a sodium ion battery polyanion cathode material according to claim 1, characterized in that: The electrolyte is a mixed solution formed by dissolving 1 mol / L sodium perchlorate in ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, and adding 5% by mass fluoroethylene carbonate.

8. The preparation method and application of a sodium ion battery polyanion cathode material according to claim 1, characterized in that: The preparation method of the modified graphene oxide is: T1 composite intermediate synthesis and preliminary reaction: Add 10-15 parts of vinyl polyoxyethylene ether, 5-10 parts of hydrogenated silicone oil, 0.05-0.4 parts of 2-vinyl-5,5-dimethyl-1,3,2-dioxaborane, and 1000-1200 parts of toluene to a reactor by mass and stir evenly. Then add 0.01-0.05 parts of chloroplatinic acid catalyst, raise the temperature to 80-90°C to carry out hydrosilylation reaction, and continue stirring for 4-6 hours; T2: Add 110-130 parts of graphene oxide, stir at 85-95°C for 45-75 minutes, and disperse by ultrasound at an ultrasonic power of 80-120 W for 20-40 minutes; allow the intermediate to fully react with the hydroxyl groups on the surface of the graphene oxide, centrifuge, wash, and vacuum dry at 55-65°C for 10-14 hours to obtain modified graphene oxide.