A sodium-ion battery cathode material prepared using cryogenic technology and its preparation method

Abstract

This invention discloses a sodium-ion battery cathode material prepared using cryogenic technology and its preparation method, relating to the field of sodium-ion battery technology. The cathode material, prepared using cryogenic technology, comprises a substrate and a coating covering the surface of the substrate. The substrate comprises the following components: 70-80 parts of positive electrode active material, 1-5 parts of conductive agent, 5-15 parts of binder A, and 30-45 parts of solvent A. The coating comprises the following components: 5-8 parts of conductive agent, 3-5 parts of binder B, 2-5 parts of corrosion inhibitor, 1-2 parts of transition metal salt compound, and 15-20 parts of solvent B. By introducing a corrosion inhibitor with a specific chemical structure combined with the coating design, a uniform and dense protective layer is formed on the electrode surface, effectively isolating it from electrolyte corrosion. The corrosion inhibitor core consumes corrosive substances through passivation and reversible redox reactions, significantly slowing down the interfacial corrosion rate, especially under long-term cycling and harsh environments.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, specifically to a sodium-ion battery cathode material prepared based on cryogenic technology and its preparation method. Background Technology

[0002] Sodium-ion batteries, as an emerging energy storage technology, have received widespread attention in recent years. Compared to lithium-ion batteries, sodium-ion batteries have significant advantages such as abundant resources (high sodium reserves), low cost (no reliance on scarce lithium mines), and environmental friendliness, showing great potential in large-scale energy storage systems, electric vehicles, and portable electronic devices. However, in terms of cathode materials, existing technologies still face many challenges, among which corrosion is particularly prominent, directly affecting the battery's cycle life and overall performance.

[0003] In existing sodium-ion battery systems, the interfacial reaction between the positive electrode active material and the electrolyte easily leads to corrosion. This is mainly due to the redox reaction between highly active components in the electrolyte and the positive electrode surface during charge and discharge, generating byproducts that corrode the active layer of the positive electrode material. Corrosion not only accelerates the degradation and structural collapse of the active material but also damages the conductive network, manifesting as rapid capacity decay (e.g., capacity retention below 80% after 100 cycles), increased internal resistance, and decreased thermal stability. For example, under high temperature or high voltage conditions, intensified corrosion may lead to battery short circuits or thermal runaway, posing safety hazards.

[0004] More specifically, existing methods for improving corrosion resistance have limitations. While common corrosion inhibitors can suppress interfacial corrosion to some extent, their inhibition efficiency is low and their compatibility is poor. Some corrosion inhibitors are easily decomposed in the alkaline environment of sodium-ion batteries, losing their protective effect; or they may undergo side reactions with conductive agents, affecting electron conduction. In addition, traditional preparation processes (such as wet coating and heat treatment) are difficult to achieve uniform dispersion of corrosion inhibitors, resulting in incomplete or uneven coatings that cannot effectively isolate corrosive media. These problems are particularly evident during long-term cycling, limiting the commercial application of batteries.

[0005] While cryogenic technology, as an emerging preparation method, has been applied in lithium-ion batteries, its application in sodium-ion battery cathode materials is still immature. Existing cryogenic processes mostly focus on substrate shaping, neglecting the synergistic optimization of coatings and corrosion inhibitors.

[0006] Therefore, there is an urgent need to develop a new type of sodium-ion battery cathode material, which can solve the above-mentioned corrosion problems through innovative freezing technology and a highly efficient corrosion inhibitor system. Summary of the Invention

[0007] The purpose of this invention is to address the problems of severe corrosion and low corrosion inhibitor efficiency in existing sodium-ion battery cathode materials by providing a high-performance sodium-ion battery cathode material prepared using cryogenic technology. This material achieves uniform bonding between the substrate and coating by introducing a corrosion inhibitor with a specific chemical structure (such as the compound shown in Formula 1) and combining it with a two-stage cryogenic process (including primary cryogenic solidification and secondary cryogenic-heat treatment). This effectively inhibits electrolyte erosion, improves corrosion resistance, cycle stability, and safety, thereby solving the risks of capacity decay and thermal runaway. Furthermore, this design optimizes the conductive network and corrosion inhibitor dispersion, ensuring reliable long-term performance.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is: a sodium-ion battery cathode material prepared based on cryogenic technology, wherein the cathode material comprises a substrate and a coating covering the surface of the substrate.

[0009] The matrix comprises the following components: 70-80 parts of positive electrode active material, 1-5 parts of conductive agent, 5-15 parts of binder A, and 30-45 parts of solvent A;

[0010] The coating comprises the following components: 5-8 parts of conductive agent, 3-5 parts of binder B, 2-5 parts of corrosion inhibitor, 1-2 parts of transition metal salt compound, and 15-20 parts of solvent B.

[0011] The corrosion inhibitor is a compound represented by chemical formula 1:

[0012] Chemical Formula 1: ;

[0013] R1 in the chemical formula 1 is a substituent, and R1 is hydrogen, deuterium, methyl, hydroxyl, fluorine, or ethyl.

[0014] Furthermore, the positive electrode active material is selected from a mixture of Na2FeP2O7 and Na3V2(PO4)3, with a mass ratio of 1.25:0.75.

[0015] Furthermore, the conductive agent is selected from at least one of conductive carbon black, acetylene black, Ketjen black, and carbon nanotubes.

[0016] Furthermore, the adhesive A is selected from: polyvinylidene fluoride;

[0017] The binder B is selected from sodium carboxymethyl cellulose.

[0018] Furthermore, the corrosion inhibitor is selected from any one of the compounds shown in the following structures:

[0019] ;

[0020] ;

[0021] .

[0022] Furthermore, the transition metal salt compound is selected from at least one of nickel sulfate, cobalt chloride, and manganese acetate.

[0023] Furthermore, solvent A is selected from: N-methylpyrrolidone;

[0024] The solvent B is selected from: water.

[0025] A method for preparing a sodium-ion battery cathode material based on cryogenic technology includes the following steps:

[0026] a. Preparation of matrix slurry: The positive electrode active material, conductive agent, binder A and solvent A are mixed and uniformly dispersed in a mixer to form a slurry mixture;

[0027] b. Coating the substrate: The slurry mixture is coated onto the surface of the current collector, and the coating thickness is controlled to be 50-150 μm;

[0028] c. Primary freezing treatment: Place the coated current collector in a freezing device and freeze it at -40℃ to -20℃ for 2-6 hours;

[0029] d. Drying the matrix: The sample frozen in step c is treated in a vacuum drying oven at a temperature of 60-80℃ for 4-8 hours to obtain the matrix;

[0030] e. Preparation of coating slurry: The conductive agent, binder B, corrosion inhibitor, transition metal salt compound and solvent B are mixed and ultrasonically dispersed to form a coating slurry;

[0031] f. Coating: The coating slurry is uniformly coated onto the surface of the substrate, with a coating thickness of 10-30 μm;

[0032] g. Secondary freezing and curing: The coated sample is frozen again at -30℃ to -10℃ for 1-4 hours, then heat-treated at 80-120℃ for 1-3 hours, and cooled to room temperature to obtain a sodium-ion battery cathode material prepared based on freezing technology.

[0033] Furthermore, steps c and g are performed under a nitrogen atmosphere.

[0034] Furthermore, step d is performed under a vacuum degree ≤ 0.1 MPa;

[0035] The heat treatment in step g adopts a gradient heating method: the temperature is increased at a rate of 2℃ / min.

[0036] The corrosion inhibitor described in this invention participates in the electron transfer process at the electrode interface. Its molecular conductivity promotes uniform electron distribution within the coating, synergistically forming a stable conductive network with the conductive agent. The core material, through passivation, keeps the electrode surface in a low-activity state: during charge and discharge, it consumes corrosive substances through reversible redox reactions, slowing down the interfacial corrosion rate. This mechanism solves the problems of low efficiency and poor compatibility of existing corrosion inhibitors, ensuring long-term corrosion inhibition through the stability of the core material. The mechanism of action of the corrosion inhibitor also relies on the two-stage freezing process of this invention. The core material is uniformly dispersed in the coating slurry through ultrasonication and forms a micro-ordered structure during freeze-curing. This structure ensures uniform coverage of the corrosion inhibitor core material on the substrate surface, avoiding the problem of incomplete coatings in traditional methods. The heat treatment step further solidifies the interaction between the core material and transition metal salt compounds, forming a more stable composite protective layer.

[0037] In this invention, key components work synergistically to construct a multi-layered protective structure within the cathode substrate and coating, effectively inhibiting electrode interface corrosion and improving overall electrochemical performance. The corrosion inhibitor, as the core component, mitigates interface corrosion by consuming corrosive substances such as reactive oxygen species in the electrolyte through its molecular core passivation and reversible redox reactions, and promotes uniform electron distribution through its conductivity. It also forms a composite protective layer with transition metal salts through coordination, enhancing passivation stability and thermomechanical strength. The conductive agent constructs a three-dimensional conductive network within the substrate and coating, reducing internal resistance and preventing localized corrosion, and synergistically improves electron transfer efficiency with the conductivity of the corrosion inhibitor. The binder provides mechanical support to the substrate and dispersion of coating components, ensuring uniform coverage and interfacial bonding of the corrosion inhibitor. The positive electrode active material forms a stable framework after freeze-drying, and its highly active surface is protected by the coating. The synergistic effect of the above components is achieved through a two-stage freezing process: primary freezing (-40℃ to -20℃, nitrogen atmosphere) solidifies the solvent in the matrix slurry to form a porous structure, facilitating coating penetration; secondary freezing (-30℃ to -10℃) combined with gradient heating heat treatment (2℃ / min, 80–120℃) promotes the orderly arrangement and solidification of corrosion inhibitors, transition metal salts, and conductive agents to form a microscopic composite protective layer. Ultimately, this synergistic system significantly inhibits corrosion, improves cycle stability, and enhances thermal safety.

[0038] Compared with the prior art, the beneficial effects of the present invention are:

[0039] 1. Significantly Improved Corrosion Resistance: By introducing corrosion inhibitors with specific chemical structures (such as the compound shown in Formula 1) and combining them with coating design, a uniform and dense protective layer is formed on the electrode surface, effectively isolating it from electrolyte erosion. The corrosion inhibitor core consumes corrosive substances through passivation and reversible redox reactions, significantly slowing down the interfacial corrosion rate, especially under long-term cycling and harsh environments (such as high temperature and high humidity).

[0040] 2. Enhanced Cyclic Stability and Safety: The two-stage freezing process (primary freezing of the substrate + secondary freezing-heat treatment coating) optimizes the material's microstructure, forming a porous framework that improves coating permeability and promotes the orderly arrangement of corrosion inhibitors and transition metal salts, forming a composite protective layer. This process solves the problem of uneven coating dispersion in traditional methods, significantly reducing active material degradation and structural collapse, improving electrode interface stability, and lowering the risk of capacity decay and thermal runaway.

[0041] 3. Synergistic optimization of conductivity and protection mechanisms: Enhances uniform electron distribution and maintains the integrity of the conductive network; coordinates with corrosion inhibitors to improve the thermomechanical strength of the passivation layer; ensures tight bonding between the protective layer and the substrate. This comprehensively improves the battery's performance robustness under harsh conditions such as corrosive environments and humid aging, extending its service life. Attached Figure Description

[0042] Figure 1 This is the NMR spectrum of the corrosion inhibitor 1 described in this invention. Detailed Implementation

[0043] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely 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.

[0044] Preparation Example 1

[0045] Preparation of corrosion inhibitor 1:

[0046] ;

[0047] 15.00 g of compound A and 120 ml of 1,4-dioxane were placed in a reaction vessel and stirred until uniformly dispersed. Then, 14.17 g of triethylamine was added and stirred until uniformly dispersed. Next, 60 ml of 1,4-dioxane containing 14.70 g of compound B was slowly added dropwise. The mixture was stirred at 60 °C for 10 h under a continuous nitrogen flow. After the reaction was complete, the reaction solution was slowly added to water at 4 °C, ensuring the temperature did not exceed 20 °C. The mixture was stirred, allowed to stand, and separated. The organic phase was retained and evaporated to dryness. The organic phase was purified by column chromatography (silica gel column chromatography, mixed solution of n-heptane / ethyl acetate). The purified solution was evaporated to dryness to obtain 21.37 g of compound C. The structure of the compound was identified by mass spectrometry at 353 using M / Z MS + H₂. + test.

[0048] ;

[0049] 21.37 g of compound C and 230 ml of DMF were placed in a reaction vessel and stirred until evenly dispersed. Then, under a continuous nitrogen flow, 25.75 g of compound D, 16.74 g of potassium carbonate, 1.82 g of urea, and 0.3 g of palladium acetate were added sequentially. The mixture was heated to 85 °C and reacted for 6 h. The mixture was filtered through diatomaceous earth, and the filtrate was collected, evaporated to dryness, and purified by column chromatography (silica gel column chromatography, mixed solution of n-heptane / ethyl acetate). The purified filtrate yielded 32.23 g of corrosion inhibitor 1. The structure of the compound was identified by mass spectrometry (MS / Z) at 671 using M / Z MS + H₂. + test.

[0050] The corrosion inhibitor 1 was identified by nuclear magnetic resonance (Chloroform-d). Figure 1 : δ 8.17 (dd, 1H), 8.00 – 7.94(m, 2H), 7.78 (dd, 1H), 7.73 – 7.68 (m, 2H), 7.62 (t, 1H), 7.54 (d, 1H), 6.97(d, 1H), 4.78 (s, 2H), 4.52 (s, 2H), 2.75 (q, 4H), 2.51 – 2.20 (m, 4H), 1.88– 1.61 (m, 4H), 1.15 (m, 6H).

[0051] Preparation Examples 2-6

[0052] In Preparation Examples 2-6, corrosion inhibitors 2-6 were prepared sequentially, following the preparation method of Preparation Example 1, except that compound B was replaced, and the rest remained the same as in Preparation Example 1, as shown in Table 1.

[0053] Table 1. Structures of Compound B, corrosion inhibitors, and structural identification data of corrosion inhibitors involved in Preparation Examples 2-6.

[0054]

[0055] Example 1

[0056] Preparation of a sodium-ion battery cathode material based on cryogenic technology:

[0057] 1. Raw material formula

[0058] 1.1 Matrix components:

[0059] Positive electrode active material: 75.0 parts, of which 46.875 parts are Na2FeP2O7 and 28.125 parts are Na3V2(PO4)3 (mass ratio 1.25:0.75).

[0060] Conductive agent: 3.0 parts, selected from: carbon nanotubes;

[0061] Adhesive A: 10.0 parts, selected from: polyvinylidene fluoride;

[0062] Solvent A: 37.5 parts, selected from N-methylpyrrolidone.

[0063] 1.2 Coating components:

[0064] Conductive agent: 6.5 parts, selected from: Ketjen Black;

[0065] Binder B: 4.0 parts, selected from sodium carboxymethyl cellulose;

[0066] Corrosion inhibitor: 3.5 parts, selected from: corrosion inhibitor 1, corrosion inhibitor 1 prepared in preparation example 1;

[0067] Transition metal salt compounds: 1.5 parts, selected from: nickel sulfate;

[0068] Solvent B: 17.5 parts, selected from: water (deionized water).

[0069] 2. Preparation method

[0070] a. Preparation of matrix slurry: The matrix components (75.0 parts of positive electrode active material, 3.0 parts of conductive carbon nanotubes, 10.0 parts of binder A polyvinylidene fluoride, and 37.5 parts of solvent A N-methylpyrrolidone) are added to a high-speed mixer and mixed at 50°C and 1000 rpm for 30 minutes to form a uniform slurry mixture;

[0071] b. Coating the substrate: The slurry mixture is uniformly coated onto the surface of the aluminum foil current collector (thickness 20μm) using a doctor blade coater, with the coating thickness controlled at 100μm and the coating speed set at 0.5m / min;

[0072] c. Primary freezing treatment: The coated current collector is transferred to a freezing device and frozen at -30°C for 4 hours under a nitrogen atmosphere, with the freezing rate controlled at 5°C / min;

[0073] d. Drying the matrix: Place the frozen sample in a vacuum drying oven with a vacuum degree ≤0.08MPa, a temperature of 70℃, and a drying time of 6 hours to obtain the matrix;

[0074] e. Preparation of coating slurry: The coating components (6.5 parts of conductive agent Ketjen black, 4.0 parts of binder B sodium carboxymethyl cellulose, 13.5 parts of corrosion inhibitor, 1.5 parts of transition metal salt compound nickel sulfate, and 17.5 parts of solvent B water) are added to an ultrasonic disperser and ultrasonically treated at a frequency of 40 kHz for 20 minutes to form a coating slurry;

[0075] f. Coating: The coating slurry is uniformly coated onto the dry substrate surface using a spraying device, with the coating thickness controlled at 20μm and the spraying pressure at 0.2MPa;

[0076] g. Secondary freezing and curing: The coated sample was subjected to secondary freezing treatment, frozen at -20°C for 2 hours under a nitrogen atmosphere; then transferred to a heat treatment furnace, and heated from room temperature to 100°C using a gradient heating method (rate 2°C / min), held at that temperature for 2 hours, and finally naturally cooled to room temperature to obtain the sodium-ion battery cathode material prepared based on freezing technology.

[0077] Examples 2-6

[0078] The preparation of a sodium-ion battery cathode material based on cryogenic technology is carried out by referring to the preparation method of Example 1, except that the corrosion inhibitor is replaced with corrosion inhibitor 2-corrosion inhibitor 6 prepared in Preparation Examples 2-6, and the rest remains unchanged.

[0079] Comparative Example 1

[0080] The preparation of a sodium-ion battery cathode material based on cryogenic technology is carried out according to the preparation method of Example 1, except that the corrosion inhibitor is replaced with 2,2'-[[(methyl-1H-benzotriazol-1-yl)methyl]amino]diethanol (CAS No.: 88477-37-6, a commonly used corrosion inhibitor), and the rest remains unchanged.

[0081] Comparative Example 2

[0082] The preparation of a sodium-ion battery cathode material based on cryogenic technology is carried out by referring to the preparation method of Example 1, except that the corrosion inhibitor is replaced with triethylene glycol bismaleate (CAS: 66790-57-6, a commonly used corrosion inhibitor), while the rest remain unchanged.

[0083] Comparative Example 3

[0084] The preparation of a sodium-ion battery cathode material based on cryogenic technology is carried out by referring to the preparation method of Example 1, except that the corrosion inhibitor is replaced with zinc sulfate (a commonly used corrosion inhibitor), while the rest remains unchanged.

[0085] Comparative Example 4

[0086] The preparation of a sodium-ion battery cathode material based on cryogenic technology is carried out according to the preparation method of Example 1, except that no corrosion inhibitor is added and the rest remains unchanged.

[0087] Comparative Example 5

[0088] The preparation of a sodium-ion battery cathode material based on cryogenic technology is carried out according to the preparation method of Example 1, except that the transition metal salt compound is not added and the rest remains unchanged.

[0089] Comparative Example 6

[0090] The preparation of a sodium-ion battery cathode material based on cryogenic technology is carried out according to the preparation method of Example 1, except that Na3V2(PO4)3 is not added and the rest remain unchanged.

[0091] Performance testing:

[0092] Sodium-ion batteries were fabricated by assembling a sodium-ion battery cathode material prepared using cryogenic technology as the cathode material in the above embodiments and comparative examples.

[0093] Test Method 1: At 25℃, charge the battery at a constant current of 0.5C to 4.0V, then charge at a constant voltage until the current is less than or equal to 0.01mA. Let it rest for 5 minutes, then discharge at a constant current of 0.5C to 2.5V, and let it rest for another 5 minutes. This constitutes one charge-discharge cycle. The discharge specific capacity of this cycle is recorded as the discharge specific capacity of the battery in the first cycle. Perform 300 charge-discharge cycles using the above method, and record the discharge specific capacity of the 300th cycle. Then, calculate the cycle retention rate by dividing the discharge specific capacity of the 300th cycle by the discharge specific capacity of the first cycle, multiplied by 100%. The data is shown in Table 2.

[0094] Test Method 2: The sodium-ion battery cathode material prepared using cryogenic technology in the above examples and comparative examples was immersed in a 1M NaClO4 aqueous solution, heated to 50°C, and immersed for 400 hours. After removal, the surface was rinsed with deionized water and then air-dried. This material was used as the cathode to assemble sodium-ion batteries. Tests were conducted according to Test Method 1, and the discharge specific capacity after the 300th cycle was recorded. The data are shown in Table 2.

[0095] Test Method 3: The sodium-ion battery cathode material prepared using cryogenic technology in the above examples and comparative examples was stored at 60°C and 85% RH for 100 days, and then used as the cathode material to assemble sodium-ion batteries. The batteries were tested according to Test Method 1, and the discharge specific capacity after the 300th cycle was recorded. The data are shown in Table 2.

[0096] Table 2 Performance test data of a sodium-ion battery cathode material prepared using cryogenic technology in the examples and comparative examples.

[0097]

[0098] Several key characteristics were observed when analyzing the overall data trends in Table 2: First, all examples (1-6) exhibited high cycle retention rates under normal cycling, electrolyte corrosion, and damp heat aging corrosion conditions, indicating that the corrosion inhibitor combined with the freezing process of the present invention can significantly improve long-term stability. Second, although the retention rates of the examples decreased slightly in corrosive environments (such as electrolyte and damp heat aging), the decrease was relatively gradual, highlighting the effective protection capability of the coating system against harsh conditions. In contrast, the overall performance of the comparative examples (1-6) deteriorated significantly, especially under corrosive conditions where the retention rate decreased more sharply. This reveals that traditional corrosion inhibitors or the absence of key components can exacerbate performance degradation, leading to a shortened cycle life. Overall, the data trends emphasize the advantages of the present invention in suppressing interfacial corrosion and improving battery robustness, and achieve a more uniform protective effect through component synergy.

[0099] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A sodium-ion battery cathode material prepared based on a freeze technology, characterized in that, The positive electrode material comprises a base body and a coating layer coated on the surface of the base body: The base body comprises the following components: 70-80 parts of positive electrode active material, 1-5 parts of conductive agent, 5-15 parts of binder A, 30-45 parts of solvent A; The coating layer comprises the following components: 5-8 parts of conductive agent, 3-5 parts of binder B, 2-5 parts of corrosion inhibitor, 1-2 parts of transition metal salt compound, 15-20 parts of solvent B; The corrosion inhibitor is a compound represented by Chemical Formula 1: Chemical Formula 1: ; R1 in the Chemical Formula 1 is a substituent, and R1 is hydrogen, deuterium, methyl, hydroxyl, fluorine, ethyl; The positive electrode active material is a mixture of Na2FeP2O7 and Na3V2(PO4)3 in a mass ratio of 1.25:0.75; The transition metal salt compound is selected from at least one of nickel sulfate, cobalt chloride, and manganese acetate; The preparation method of the sodium ion battery positive electrode material based on the freezing technology comprises the following steps: a. Preparing base body slurry: mixing the positive electrode active material, conductive agent, binder A, and solvent A, and uniformly dispersing in a blender to form a slurry-like mixture; b. Coating the base body: coating the slurry-like mixture on the surface of the current collector, and controlling the coating thickness to be 50-150 μm; c. Primary freezing treatment: placing the coated current collector in a freezing device and freezing at-40℃ to-20℃ for 2-6 hours; d. Drying the base body: treating the frozen sample in step c in a vacuum drying oven at a temperature of 60-80℃ for 4-8 hours to obtain the base body; e. Preparing coating slurry: mixing the conductive agent, binder B, corrosion inhibitor, transition metal salt compound, and solvent B, and uniformly dispersing by ultrasonic to form coating slurry; f. Coating the coating layer: uniformly coating the coating slurry on the surface of the base body with a coating thickness of 10-30 μm; g. Secondary freezing and solidification: re-freezing the sample after coating the coating layer at-30℃ to-10℃ for 1-4 hours, and heat treating at 80-120℃ for 1-3 hours, and cooling to room temperature to obtain a sodium ion battery positive electrode material based on the freezing technology; The binder A is polyvinylidene fluoride; The binder B is sodium carboxymethyl cellulose.

2. The sodium-ion battery cathode material prepared based on the freezing technology according to claim 1, characterized in that, The conductive agent is at least one of conductive carbon black, acetylene black, ketjen black, and carbon nanotube.

3. The sodium-ion battery cathode material prepared based on the freezing technology according to claim 1, characterized in that, The corrosion inhibitor is any one of the compounds represented by the following structure: ； ； 。 4. The sodium-ion battery cathode material prepared based on the freezing technology according to claim 1, characterized in that, The solvent A is N-methyl pyrrolidone; The solvent B is water.

5. The sodium-ion battery cathode material prepared based on the freezing technique according to claim 1, characterized in that, The steps c and g are carried out in a nitrogen atmosphere.

6. The sodium-ion battery cathode material prepared based on the freezing technique according to claim 1, characterized in that, The step d is carried out under a vacuum degree of ≤0.1 MPa; The heat treatment in step g adopts a gradient heating mode with a heating rate of 2℃ / min.

Images