A high capacity sodium-ion battery layered-oxide cathode material

Abstract

The application discloses a high-capacity sodium ion battery layered oxide positive electrode material and relates to the technical field of sodium ion battery preparation. The high-capacity sodium ion battery layered oxide positive electrode material is prepared by ball milling a precursor and sodium carbonate and then performing roasting treatment. During the roasting treatment, the polysiloxane main chain in the molecule forms amorphous silicon dioxide. The silicon dioxide can inhibit the transition metal ions from dissolving into the electrolyte in the cycle process, thereby avoiding the capacity attenuation and the negative electrode SEI film damage caused by the dissolution of the transition metal ions. Meanwhile, the silicon dioxide can be used as a buffer matrix to absorb mechanical stress and prevent the particles from being broken, so that the cycle stability of the material is remarkably improved. The boron element and part of the silicon elements on the main chain form boron-silicon oxide, which can separate the sodium layer and the transition metal layer, widen the diffusion channel of sodium ions, lower the ion migration energy barrier, improve the rate performance, hinder the migration of the transition metal ions to the sodium layer and reduce the mixing of the cations.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery preparation technology, specifically to a high-capacity sodium-ion battery layered oxide cathode material. Background Technology

[0002] With rapid socio-economic development, energy demand is soaring. However, reserves of non-renewable energy sources such as coal, oil, and natural gas are limited, making an energy crisis imminent. To meet global energy needs, renewable and clean energy has seen rapid development. Due to the inherent intermittency and volatility of clean energy, power storage systems are crucial for its large-scale application. Sodium-ion batteries have attracted significant attention due to their low cost-effectiveness, extremely high sodium abundance, and lithium intercalation chemistry similar to lithium-ion batteries. Sodium is abundant on Earth, widely distributed, and inexpensive to extract, giving sodium-ion batteries unparalleled development potential in large-scale energy storage. However, current sodium-ion batteries suffer from poor cycle stability, with a significant capacity decrease after multiple cycles, resulting in a short lifespan. Summary of the Invention

[0003] The purpose of this invention is to provide a high-capacity layered oxide cathode material for sodium-ion batteries, which solves the problems of general cycle stability and short battery life of current sodium-ion batteries.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] A high-capacity layered oxide cathode material for sodium-ion batteries, specifically comprising the following steps:

[0006] Step A1: Mix ferrous chloride tetrahydrate, sodium citrate, and deionized water evenly. Stir and add sodium ferrocyanide decahydrate aqueous solution at a speed of 600-800 r / min and a temperature of 10-15℃. Heat to 20-25℃ and react for 5-7 hours. Filter to remove the filtrate. Mix the substrate, modified ligand, and DMF evenly. Soak at 20-25℃ for 15-20 hours. Remove and dry to obtain the modified additive.

[0007] Step A2: Mix nickel sulfate, ferrous sulfate, manganese sulfate, titanium sulfate, citric acid, and deionized water evenly, purge with nitrogen for protection, stir at 1000-1200 r / min and 55-60℃, add sodium hydroxide solution to maintain pH 11, and react for 0.5-1 h. Then add the modifying additive and continue the reaction for 1-1.5 h. Filter to remove the filtrate and dry to obtain the precursor.

[0008] Step A3: Add the precursor and sodium carbonate to a ball mill and ball mill for 2-3 hours at a speed of 300 r / min. Then, under an oxygen atmosphere with a heating rate of 2-5℃, calcine at 450-500℃ for 4-6 hours, then calcine at 850-900℃ for 10-12 hours. Cool to room temperature to obtain a high-capacity sodium-ion battery layered oxide cathode material.

[0009] Furthermore, the ratio of ferrous chloride tetrahydrate, sodium citrate, deionized water, sodium ferrocyanide decahydrate aqueous solution, and modified ligand in step A1 is 0.65 mmol:1 mmol:50 mL:50 mL:30 mg, and the concentration of sodium ferrocyanide decahydrate aqueous solution is 0.01 mmol / mL.

[0010] Furthermore, the ratio of nickel sulfate, ferrous sulfate, manganese sulfate, titanium sulfate, citric acid, and deionized water used in step A2 is 0.4 mol: 0.2 mol: 0.3 mol: 0.1 mol: 1 mol: 1 L.

[0011] Furthermore, the mass ratio of the precursor to sodium carbonate in step A3 is 20:1.

[0012] Furthermore, the modified ligand is prepared by the following steps:

[0013] Step B1: Lithium dimethylvinylsilane and tetrahydrofuran are mixed and stirred at 150-200 r / min and 0°C. Octamethylcyclotetrasiloxane is added, and the mixture is heated to 25-30°C and reacted for 20-25 h. Then, tetrachlorosilane is added and the reaction is continued for 1-1.5 h to obtain branched polysiloxane. The branched polysiloxane, thioglycerol, benzophenone and tetrahydrofuran are mixed evenly and protected with nitrogen. The mixture is then reacted at 120-150 r / min and 20-25°C under ultraviolet irradiation for 20-30 min to obtain pretreated polysiloxane.

[0014] Step B2: Mix the pretreated polysiloxane, 4-formylphenylboronic acid, p-toluenesulfonic acid and m-xylene evenly, purge with nitrogen, and react for 5-7 hours at a speed of 150-200 r / min and a temperature of 110-120℃ to obtain the modified polysiloxane. Mix the modified polysiloxane, melamine, 3A molecular sieve and DMF evenly, purge with nitrogen, and react for 2-3 hours at a speed of 200-300 r / min and a temperature of 110-120℃ to obtain the functionalized polysiloxane.

[0015] Step B3: Mix functionalized polysiloxane, ferric chloride and DMF, stir and add hydroxylamine hydrochloride at a speed of 150-200 r / min and a temperature of 30-40℃, raise the temperature to 140-150℃ and react for 4-6 h to obtain the modified ligand.

[0016] Furthermore, in step B1, the molar ratio of Si-Cl bonds on lithium dimethylvinylsiloxane, octamethylcyclotetrasiloxane, and tetrachlorosilane is 1:3:1, the molar ratio of branched polysiloxane and thioglycerol is 1:4, and the amount of benzophenone used is 0.2% of the mass of thioglycerol.

[0017] Furthermore, in step B2, the molar ratio of the pretreated polysiloxane and 4-formylphenylboronic acid is 1:4, the amount of p-toluenesulfonic acid is 1% of the mass of 4-formylphenylboronic acid, the molar ratio of the modified polysiloxane and melamine is 2n+1:n, where n is a natural number greater than 1, and the amount of 3A molecular sieve is 3% of the mass of melamine.

[0018] Furthermore, the molar ratio of the aldehyde group, ferric chloride, and hydroxylamine hydrochloride on the functionalized polysiloxane described in step B3 is 10:5:12.

[0019] The beneficial effects of this invention are as follows: The high-capacity sodium-ion battery layered oxide cathode material prepared by this invention is produced by reacting ferrous chloride tetrahydrate, sodium ferrocyanide decahydrate, and citric acid as raw materials to form an inorganic framework similar to Prussian blue. This framework is then reacted with modified ligands, allowing the cyano groups on the modified ligands to coordinate with the empty coordination sites in the inorganic framework, thus obtaining a modified additive. Nickel sulfate, ferrous sulfate, manganese sulfate, titanium sulfate, and citric acid are mixed and reacted, allowing citric acid to act as a complexing agent and react with metal ions to form a precipitate. The modified additive is then added to continue the reaction, allowing the metal precipitate to coat the modified additive, thus obtaining a precursor. The precursor and sodium carbonate are ball-milled and then calcined to obtain the high-capacity sodium-ion battery layered oxide cathode material.

[0020] The modified ligand is formed by using dimethylvinylsilyllithium as an initiator and octamethylcyclotetrasiloxane as a polymerization monomer to form a polysiloxane with a vinyl end and a silyllithium end. Tetrachlorosilane is then added, causing the Si-Cl bond on the tetrachlorosilane to react with the silyllithium to obtain a branched polysiloxane. The branched polysiloxane is then reacted with thioglycerol, causing the double bond on the branched polysiloxane to react with the mercapto group on the thioglycerol to obtain a pretreated polysiloxane. The pretreated polysiloxane is then reacted with 4-formylphenylboronic acid, causing the diol on the pretreated polysiloxane to react with the boric acid on the 4-formylphenylboronic acid to obtain a modified polysiloxane. The modified polysiloxane is then reacted with melamine, causing the aldehyde group on the modified polysiloxane to react with the amino group on the melamine to obtain a functionalized polysiloxane. The functionalized polysiloxane is then treated with ferric chloride and hydroxylamine hydrochloride, causing the mercapto group to be converted into a cyano group to obtain the modified ligand.

[0021] During calcination, the polysiloxane backbone of the modified ligand forms amorphous silica. Silica can inhibit the dissolution of transition metal ions into the electrolyte during cycling, thereby avoiding capacity decay and damage to the negative electrode SEI film caused by dissolution. At the same time, it acts as a buffer matrix, absorbing mechanical stress and preventing particle breakage, thus significantly improving the cycling stability of the material. The boron element in the modified ligand forms borosilicate oxide with some silicon elements on the backbone, which can expand the sodium layer and transition metal layer, widen the diffusion channel of sodium ions, thereby reducing the ion migration barrier and improving rate performance. At the same time, it can hinder the migration of transition metal ions to the sodium layer and reduce cation mixing. The doping of nitrogen element allows nitrogen atoms to be embedded in some of the incompletely oxidized, stable sp² carbon skeleton to form nitrogen-doped carbon, thereby improving electronic conductivity. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1: A high-capacity layered oxide cathode material for sodium-ion batteries, specifically comprising the following steps:

[0024] Step A1: Mix ferrous chloride tetrahydrate, sodium citrate and deionized water evenly. Stir and add sodium ferrocyanide decahydrate aqueous solution at 10°C and 600 r / min. Heat to 20°C and react for 5 h. Filter to remove filtrate. Mix substrate, modified ligand and DMF evenly. Soak at 20°C for 15 h. Remove and dry to obtain modified additive.

[0025] Step A2: Mix nickel sulfate, ferrous sulfate, manganese sulfate, titanium sulfate, citric acid, and deionized water evenly, purge with nitrogen for protection, stir at 1000 r / min and 55℃, add sodium hydroxide solution to maintain pH 11, react for 0.5 h, add modifying additive, continue reaction for 1 h, filter to remove filtrate and dry to obtain the precursor;

[0026] Step A3: Add the precursor and sodium carbonate to a ball mill and ball mill for 2 hours at a speed of 300 r / min. Then, under an oxygen atmosphere with a heating rate of 2°C, calcine at 450°C for 4 hours, then calcine at 850°C for 10 hours. Cool to room temperature to obtain a high-capacity sodium-ion battery layered oxide cathode material.

[0027] The ratio of ferrous chloride tetrahydrate, sodium citrate, deionized water, sodium ferrocyanide decahydrate aqueous solution, and modified ligand in step A1 is 0.65 mmol:1 mmol:50 mL:50 mL:30 mg, and the concentration of sodium ferrocyanide decahydrate aqueous solution is 0.01 mmol / mL.

[0028] The ratio of nickel sulfate, ferrous sulfate, manganese sulfate, titanium sulfate, citric acid, and deionized water used in step A2 is 0.4 mol: 0.2 mol: 0.3 mol: 0.1 mol: 1 mol: 1 L.

[0029] The mass ratio of the precursor to sodium carbonate in step A3 is 20:1.

[0030] The modified ligand is prepared by the following steps:

[0031] Step B1: Lithium dimethylvinylsilane and tetrahydrofuran were mixed and stirred at 150 r / min and 0°C. Octamethylcyclotetrasiloxane was added, the temperature was raised to 25°C, and the reaction was carried out for 20 h. Then tetrachlorosilane was added, and the reaction was continued for 1 h to obtain branched polysiloxane. The branched polysiloxane, thioglycerol, benzophenone and tetrahydrofuran were mixed evenly, and nitrogen gas was introduced for protection. The reaction was carried out at 120 r / min, 20°C and ultraviolet irradiation for 20 min to obtain pretreated polysiloxane.

[0032] Step B2: Mix the pretreated polysiloxane, 4-formylphenylboronic acid, p-toluenesulfonic acid and m-xylene evenly, purge with nitrogen, and react for 5 hours at 150 r / min and 110 °C to obtain the modified polysiloxane. Mix the modified polysiloxane, melamine, 3A molecular sieve and DMF evenly, purge with nitrogen, and react for 2 hours at 200 r / min and 110 °C to obtain the functionalized polysiloxane.

[0033] Step B3: Functionalized polysiloxane, ferric chloride and DMF are mixed, stirred and hydroxylamine hydrochloride is added at a speed of 150 r / min and a temperature of 30°C, the temperature is raised to 140°C and the reaction is carried out for 4 h to obtain the modified ligand.

[0034] In step B1, the molar ratio of Si-Cl bonds on lithium dimethylvinylsiloxane, octamethylcyclotetrasiloxane, and tetrachlorosilane is 1:3:1, the molar ratio of branched polysiloxane and thioglycerol is 1:4, and the amount of benzophenone used is 0.2% of the mass of thioglycerol.

[0035] In step B2, the molar ratio of pretreated polysiloxane to 4-formylphenylboronic acid is 1:4, the amount of p-toluenesulfonic acid is 1% of the mass of 4-formylphenylboronic acid, the molar ratio of modified polysiloxane to melamine is 3:1, and the amount of 3A molecular sieve is 3% of the mass of melamine.

[0036] The molar ratio of aldehyde group, ferric chloride and hydroxylamine hydrochloride on the functionalized polysiloxane described in step B3 is 10:5:12.

[0037] Example 2: A high-capacity sodium-ion battery layered oxide cathode material, specifically comprising the following steps:

[0038] Step A1: Mix ferrous chloride tetrahydrate, sodium citrate and deionized water evenly. Stir and add sodium ferrocyanide decahydrate aqueous solution at 12°C and 600 r / min. Heat to 20°C and react for 6 hours. Filter to remove filtrate. Mix substrate, modified ligand and DMF evenly. Soak at 20°C for 18 hours. Remove and dry to obtain modified additive.

[0039] Step A2: Mix nickel sulfate, ferrous sulfate, manganese sulfate, titanium sulfate, citric acid, and deionized water evenly, purge with nitrogen for protection, stir at 1000 r / min and 60℃, add sodium hydroxide solution to maintain pH 11, react for 0.5 h, add modifying additive, continue reaction for 1.5 h, filter to remove filtrate and dry to obtain the precursor;

[0040] Step A3: Add the precursor and sodium carbonate to a ball mill and ball mill for 2 hours at a speed of 300 r / min. Then, under an oxygen atmosphere with a heating rate of 2°C, calcine at 500°C for 5 hours, then calcine at 850°C for 12 hours. Cool to room temperature to obtain a high-capacity sodium-ion battery layered oxide cathode material.

[0041] The ratio of ferrous chloride tetrahydrate, sodium citrate, deionized water, sodium ferrocyanide decahydrate aqueous solution, and modified ligand in step A1 is 0.65 mmol:1 mmol:50 mL:50 mL:30 mg, and the concentration of sodium ferrocyanide decahydrate aqueous solution is 0.01 mmol / mL.

[0042] The ratio of nickel sulfate, ferrous sulfate, manganese sulfate, titanium sulfate, citric acid, and deionized water used in step A2 is 0.4 mol: 0.2 mol: 0.3 mol: 0.1 mol: 1 mol: 1 L.

[0043] The mass ratio of the precursor to sodium carbonate in step A3 is 20:1.

[0044] The modified ligand is prepared by the following steps:

[0045] Step B1: Lithium dimethylvinylsilane and tetrahydrofuran were mixed and stirred at 150 r / min and 0 °C. Octamethylcyclotetrasiloxane was added, the temperature was raised to 30 °C, and the reaction was carried out for 22 h. Then tetrachlorosilane was added, and the reaction was continued for 1.3 h to obtain branched polysiloxane. The branched polysiloxane, thioglycerol, benzophenone and tetrahydrofuran were mixed evenly, and nitrogen gas was introduced for protection. The reaction was carried out at 120 r / min, 25 °C and ultraviolet irradiation for 25 min to obtain pretreated polysiloxane.

[0046] Step B2: Mix the pretreated polysiloxane, 4-formylphenylboronic acid, p-toluenesulfonic acid and m-xylene evenly, purge with nitrogen, and react for 6 hours at 150 r / min and 115 °C to obtain the modified polysiloxane. Mix the modified polysiloxane, melamine, 3A molecular sieve and DMF evenly, purge with nitrogen, and react for 2.5 hours at 300 r / min and 115 °C to obtain the functionalized polysiloxane.

[0047] Step B3: Functionalized polysiloxane, ferric chloride and DMF are mixed, stirred and hydroxylamine hydrochloride is added at a speed of 150 r / min and a temperature of 35°C, the temperature is raised to 145°C and the reaction is carried out for 5 h to obtain the modified ligand.

[0048] In step B1, the molar ratio of Si-Cl bonds on lithium dimethylvinylsiloxane, octamethylcyclotetrasiloxane, and tetrachlorosilane is 1:3:1, the molar ratio of branched polysiloxane and thioglycerol is 1:4, and the amount of benzophenone used is 0.2% of the mass of thioglycerol.

[0049] In step B2, the molar ratio of pretreated polysiloxane to 4-formylphenylboronic acid is 1:4, the amount of p-toluenesulfonic acid is 1% of the mass of 4-formylphenylboronic acid, the molar ratio of modified polysiloxane to melamine is 5:2, and the amount of 3A molecular sieve is 3% of the mass of melamine.

[0050] The molar ratio of aldehyde group, ferric chloride and hydroxylamine hydrochloride on the functionalized polysiloxane described in step B3 is 10:5:12.

[0051] Example 3: A high-capacity sodium-ion battery layered oxide cathode material, specifically comprising the following steps:

[0052] Step A1: Mix ferrous chloride tetrahydrate, sodium citrate and deionized water evenly. Stir and add sodium ferrocyanide decahydrate aqueous solution at 800 r / min and 15℃. Heat to 25℃ and react for 7 h. Filter to remove filtrate. Mix substrate, modified ligand and DMF evenly. Soak at 25℃ for 20 h. Remove and dry to obtain modified additive.

[0053] Step A2: Mix nickel sulfate, ferrous sulfate, manganese sulfate, titanium sulfate, citric acid, and deionized water evenly, purge with nitrogen for protection, stir at 1200 r / min and 60℃, add sodium hydroxide solution to maintain pH 11, react for 1 h, add modifying additive, continue reaction for 1.5 h, filter to remove filtrate and dry to obtain the precursor;

[0054] Step A3: Add the precursor and sodium carbonate to a ball mill and ball mill for 3 hours at a speed of 300 r / min. Then, under an oxygen atmosphere with a heating rate of 5°C, calcine at 500°C for 6 hours, then calcine at 900°C for 12 hours. Cool to room temperature to obtain a high-capacity sodium-ion battery layered oxide cathode material.

[0055] The ratio of ferrous chloride tetrahydrate, sodium citrate, deionized water, sodium ferrocyanide decahydrate aqueous solution, and modified ligand in step A1 is 0.65 mmol:1 mmol:50 mL:50 mL:30 mg, and the concentration of sodium ferrocyanide decahydrate aqueous solution is 0.01 mmol / mL.

[0056] The ratio of nickel sulfate, ferrous sulfate, manganese sulfate, titanium sulfate, citric acid, and deionized water used in step A2 is 0.4 mol: 0.2 mol: 0.3 mol: 0.1 mol: 1 mol: 1 L.

[0057] The mass ratio of the precursor to sodium carbonate in step A3 is 20:1.

[0058] The modified ligand is prepared by the following steps:

[0059] Step B1: Lithium dimethylvinylsilane and tetrahydrofuran were mixed and stirred at 200 r / min and 0°C. Octamethylcyclotetrasiloxane was added, the temperature was raised to 30°C, and the reaction was carried out for 25 h. Then tetrachlorosilane was added, and the reaction was continued for 1.5 h to obtain branched polysiloxane. The branched polysiloxane, thioglycerol, benzophenone and tetrahydrofuran were mixed evenly, and nitrogen gas was introduced for protection. The reaction was carried out at 150 r / min, 25°C and ultraviolet irradiation for 30 min to obtain pretreated polysiloxane.

[0060] Step B2: Mix the pretreated polysiloxane, 4-formylphenylboronic acid, p-toluenesulfonic acid and m-xylene evenly, purge with nitrogen, and react for 7 hours at 200 r / min and 120°C to obtain the modified polysiloxane. Mix the modified polysiloxane, melamine, 3A molecular sieve and DMF evenly, purge with nitrogen, and react for 3 hours at 300 r / min and 120°C to obtain the functionalized polysiloxane.

[0061] Step B3: Functionalized polysiloxane, ferric chloride and DMF are mixed, stirred and hydroxylamine hydrochloride is added at a speed of 200 r / min and a temperature of 40°C, the temperature is raised to 150°C and the reaction is carried out for 6 h to obtain the modified ligand.

[0062] In step B1, the molar ratio of Si-Cl bonds on lithium dimethylvinylsiloxane, octamethylcyclotetrasiloxane, and tetrachlorosilane is 1:3:1, the molar ratio of branched polysiloxane and thioglycerol is 1:4, and the amount of benzophenone used is 0.2% of the mass of thioglycerol.

[0063] In step B2, the molar ratio of pretreated polysiloxane to 4-formylphenylboronic acid is 1:4, the amount of p-toluenesulfonic acid is 1% of the mass of 4-formylphenylboronic acid, the molar ratio of modified polysiloxane to melamine is 7:3, and the amount of 3A molecular sieve is 3% of the mass of melamine.

[0064] The molar ratio of aldehyde group, ferric chloride and hydroxylamine hydrochloride on the functionalized polysiloxane described in step B3 is 10:5:12.

[0065] Comparative Example 1: This comparative example uses modified polysiloxane instead of functionalized polysiloxane, while the other steps are the same as in Example 1.

[0066] Comparative Example 2: Compared with Example 1, this comparative example uses branched polysiloxane, 4-mercaptobenzaldehyde, benzophenone and tetrahydrofuran to be mixed evenly, under nitrogen protection, and reacted for 20 min at a rotation speed of 120 r / min, a temperature of 20°C and ultraviolet irradiation to obtain a product that replaces the functionalized polysiloxane. The remaining steps are the same.

[0067] Comparative Example 3: Compared with Example 1, this comparative example uses tetramethyldivinyldisiloxane instead of branched polysiloxane, while the other steps are the same.

[0068] The positive electrode materials, conductive carbon black (superP), and PVDF prepared in Examples 1-3 and Comparative Examples 1-3 were mixed and dissolved in NMP at a mass ratio of 94:3:3. After thorough stirring, the positive electrode sheets were coated onto aluminum foil using an automatic coating machine. The coated electrode sheets were dried in a vacuum at 105°C for 12 hours, and then rolled using a roller press. The rolled positive electrode sheets were cut into 12mm diameter discs. Using metallic sodium as the negative electrode sheet and a glass fiber membrane as the separator, and with 1 mmol of NaPF6 dissolved in an EC:DEC = 1:1 organic electrolyte, CR2032 coin cells were assembled in an argon-protected glove box. The 1C charge / discharge current of the battery was 240mA / g. At 25°C, the electrochemical performance of each group of batteries was tested: the voltage was 2.0-4.0V, the current was 0.1C, the first charge-discharge specific capacity was measured, the first cycle efficiency was obtained, and the finished batteries were tested for 1C cycle life. The test results are shown in Table 1 below.

[0069] Table 1

[0070] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 First week charging capacity (mH / g) 174.7 176.8 178.2 156.1 151.3 142.6 First week discharge capacity (MAh / g) 168.2 171.3 173.0 144.1 137.8 124.3 First week efficiency % 96.3 96.9 97.1 92.3 91.1 87.2 1C cycle life count 411 423 438 387 328 272

[0071] As shown in Table 1, this application has excellent cycle stability and improved service life.

[0072] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A high-capacity sodium-ion battery layered oxide cathode material, characterized in that: Specifically, the steps include the following: Step A1: Mix ferrous chloride tetrahydrate, sodium citrate and deionized water and stir, then add sodium ferrocyanide decahydrate aqueous solution. After heating and reacting, filter to remove the filtrate, mix and soak the substrate, modified ligand and DMF, take it out and dry it to obtain the modified additive. Step A2: Mix nickel sulfate, ferrous sulfate, manganese sulfate, titanium sulfate, citric acid, and deionized water evenly, purge with nitrogen for protection, stir and add sodium hydroxide solution to maintain pH alkaline, and after the reaction, add the modifying additive, continue the reaction, filter to remove the filtrate and dry to obtain the precursor. Step A3: Add the precursor and sodium carbonate to a ball mill, ball mill, then heat and calcine, and cool to room temperature to obtain a high-capacity sodium-ion battery layered oxide cathode material. The modified ligand is prepared by the following steps: Step B1: Lithium dimethylvinylsilane and tetrahydrofuran are mixed and stirred, and octamethylcyclotetrasiloxane is added. After heating and reacting, tetrachlorosilane is added and the reaction is continued to obtain branched polysiloxane. The branched polysiloxane, thioglycerol, benzophenone and tetrahydrofuran are mixed evenly, nitrogen gas is introduced for protection, and ultraviolet light is used for reaction to obtain pretreated polysiloxane. Step B2: Mix the pretreated polysiloxane, 4-formylphenylboronic acid, p-toluenesulfonic acid and m-xylene evenly, purge with nitrogen, and react to obtain modified polysiloxane. Mix the modified polysiloxane, melamine, 3A molecular sieve and DMF evenly, purge with nitrogen, and react to obtain functionalized polysiloxane. Step B3: Mix and stir the functionalized polysiloxane, ferric chloride and DMF, add hydroxylamine hydrochloride, and heat to react to obtain the modified ligand.

2. The high-capacity sodium-ion battery layered oxide cathode material according to claim 1, characterized in that: The ratio of ferrous chloride tetrahydrate, sodium citrate, deionized water, sodium ferrocyanide decahydrate aqueous solution and modified ligand in step A1 is 0.65 mmol:1 mmol:50 mL:50 mL:30 mg.

3. The high-capacity sodium-ion battery layered oxide cathode material according to claim 1, characterized in that: The ratio of nickel sulfate, ferrous sulfate, manganese sulfate, titanium sulfate, citric acid, and deionized water used in step A2 is 0.4 mol: 0.2 mol: 0.3 mol: 0.1 mol: 1 mol: 1 L.

4. The high-capacity sodium-ion battery layered oxide cathode material according to claim 1, characterized in that: The mass ratio of the precursor to sodium carbonate in step A3 is 20:

1.

5. The high-capacity sodium-ion battery layered oxide cathode material according to claim 1, characterized in that: The molar ratio of Si-Cl bonds on lithium dimethylvinylsiloxane, octamethylcyclotetrasiloxane and tetrachlorosilane in step B1 is 1:3:1, and the molar ratio of branched polysiloxane and thioglycerol is 1:

4.

6. The high-capacity sodium-ion battery layered oxide cathode material according to claim 1, characterized in that: In step B2, the molar ratio of the pretreated polysiloxane and 4-formylphenylboronic acid is 1:4, and the molar ratio of the modified polysiloxane and melamine is 2n+1:n, where n is a natural number greater than 1.

7. The high-capacity sodium-ion battery layered oxide cathode material according to claim 1, characterized in that: The molar ratio of aldehyde group, ferric chloride and hydroxylamine hydrochloride on the functionalized polysiloxane described in step B3 is 10:5:12.