Dehydration and coating method for and use of prussian blue sodium-ion battery positive electrode material

Abstract

A method for modifying a Prussian blue analogue for a sodium-ion battery positive electrode material. The method mainly comprises: with a composite conductive agent acting as a coating agent and a dehydration agent, adding a Prussian blue analogue and the conductive agent to ethyl alcohol at a certain ratio, and fully mixing same at a certain rotation speed, so as to obtain a uniform slurry; and dehydrating and coating same by means of a small-sized spray dryer, thereby achieving the modification of the Prussian blue analogue, and obtaining a composite material having a low crystal water content and high air stability. A graphene / carbon nanotube composite not only can be used as a conductive framework to improve the conductivity of an electrode, but also can be bonded to crystal water in a Prussian blue analogue at a high temperature to promote the removal of the crystal water. Moreover, a 3D space coating layer is formed therefrom, thereby reducing direct contact between the material and an electrolyte solution, inhibiting interfacial side reactions during an electrochemical process, and improving the reaction stability of the material.

Description

A dehydration and coating method and application of Prussian blue-based sodium ion battery positive electrode material Technical Field

[0001] The invention belongs to the field of production and preparation of sodium ion battery positive electrode materials, and particularly relates to a method for preparing a Prussian blue analogue. Background Art

[0002] Sodium-ion batteries (SIBs), due to their low cost and long lifespan, are considered one of the most promising large-scale energy storage systems after lithium-ion batteries. Among the various components of SIBs, electrode materials are a crucial determinant of their performance and also their largest cost contributor. Therefore, the development of cost-effective electrode materials is crucial for the large-scale commercial application of SIBs. Currently, the mainstream SIB cathode materials include polyanionic compounds, Prussian blue-based compounds (PBAs), and layered transition metal oxides. Among them, Prussian blue-based SIBs, with their three-dimensional open frameworks, abundant sodium ion storage sites, and broad sodium ion migration channels, are promising cathode candidates for large-scale SIB energy storage systems. Theoretically, Prussian blue-based SIBs offer high specific capacity and long cycle life. However, due to the presence of numerous structural defects and crystalline water in the material, their discharge capacity, cycle life, and coulombic efficiency are less than ideal. Current research focuses on the source-controlled synthesis of low-defect, high-quality Prussian blue, while relatively little research has been conducted on back-end defect repair and crystalline water removal processes. Therefore, developing efficient strategies for repairing defects and removing crystalline water has become a key focus for Prussian blue analogs in the future. At present, the crystalline water in Prussian blue-based sodium cathode materials is mainly removed by high-temperature vacuum dehydration, but the dehydrated material is very easy to absorb water again when exposed to air again. Therefore, the surface of the material is coated or doped during the dehydration process to inhibit its water absorption, improve the storage stability of the material, and improve its electrochemical performance. This will be very beneficial to promote the industrialization of Prussian blue-based sodium-ion batteries. In 2021, Wang Ziheng et al. published a study in the American Chemical Society titled "Continuous conductive network constructed by Prussian blue cubes and mesoporous carbon can improve sodium ion storage performance", which showed that mesoporous carbon can be coated on the surface of Prussian blue and has a significant effect. The conductive carbon coated on the surface of the positive electrode material can effectively inhibit the side reactions between the positive electrode material and the electrolyte, reduce the occurrence of irreversible phase changes, and reduce the charge transfer resistance of the electrode reaction, thereby improving the electrochemical performance of the material.

[0003] If PBAs can be simultaneously dehydrated and coated, their electrochemical sodium storage behavior and stability could be significantly improved. Using spray drying technology, we simultaneously remove the water of crystallization from unmodified Prussian blue and coat the surface of the material, resulting in a sodium-rich, highly crystalline Prussian blue cathode material. This is expected to further advance the commercialization of PBA-based sodium-ion batteries. Summary of the Invention

[0004] The present invention addresses the problems of existing Prussian blue-based sodium cathode materials, such as numerous defects, high crystal water content, and poor storage stability. A coating method is proposed. A conductive agent is used as a coating agent and dehydrating agent. A Prussian blue analogue and the conductive agent are added to ethanol in a specific ratio and thoroughly mixed at a specific rotational speed to obtain a uniform slurry. The Prussian blue analogue is then modified using a small spray dryer to obtain a composite material with low crystal water content and high air stability. This method has a simple process, simple equipment, and widely available raw materials, and has excellent prospects for industrialization.

[0005] In order to achieve the above object, the present invention provides a method for modifying a Prussian blue analogue, the specific steps of which are as follows:

[0006] (1) Synthesis of a Prussian blue analogue containing defects and crystalline water.

[0007] (2) The product in step (1) is mixed evenly with a conductive agent in a certain proportion.

[0008] (3) The mixture in step (2) is further stirred with a magnetic stirrer, and the uniform slurry is fed through a peristaltic pump at a certain peristaltic speed and spray-dried at a certain inlet temperature and outlet temperature.

[0009] (4) After step (3), the outlet temperature is reduced to 30-40 °C, the instrument is turned off, and the composite material is collected.

[0010] The hydrated and defective Prussian blue analogues in step (1) include hydrated and defective iron-based Prussian blue materials, hydrated and defective iron-manganese-based Prussian blue materials, hydrated and defective iron-cobalt-based Prussian blue materials, hydrated and defective iron-nickel-based Prussian blue materials, hydrated and defective iron-copper-based Prussian blue materials, hydrated and defective iron-zinc-based Prussian blue materials, hydrated and defective manganese-based Prussian blue analogues ... One or more of cobalt-based Prussian blue materials, hydrated and defective manganese-nickel-based Prussian blue materials, hydrated and defective manganese-copper-based Prussian blue materials, hydrated and defective zinc-manganese-based Prussian blue materials, hydrated and defective nickel-based Prussian blue materials, hydrated and defective zinc-based Prussian blue analogs, hydrated and defective cobalt-based Prussian blue analogs, hydrated and defective vanadium-based Prussian blue analogs, and hydrated and defective cerium-based Prussian blue analogs.

[0011] The coating agent in step (2) includes one or more of carbon nanotubes, graphene composites, aniline, pyrrole, acrylonitrile, polyacrylonitrile, polyaniline, phenolic resin, and asphalts with different softening points.

[0012] In step (2), the coating agent is spray-dried according to the mass ratio of the coating agent to the material, and the proportion of the coating agent is 1-20%.

[0013] The feed temperature in step (3) is 100-300°C, the outlet temperature is 100-250°C, and the feed rate is 50-200 ml / h.

[0014] A second aspect of the present invention provides a sodium ion battery positive electrode material, wherein the positive electrode material is prepared from the above composite material.

[0015] The preparation method of the above-mentioned sodium ion battery positive electrode is as follows: FeMn-PBA material, conductive carbon black (conductive agent) and sodium alginate (binder) are mixed according to 70:20:10 (wt%), the obtained mixture is fully ground and mixed in a mortar, transferred to a 2 ml shaking tube, several 3 mm diameter zirconium dioxide beads are added, and the mixture is fully shaken to obtain a uniform slurry, which is coated on a carbon-coated aluminum foil and placed at 80 o C in a vacuum drying oven for 12 h to completely evaporate the solvent, then cut the pieces, weigh them, and calculate the active substance loading.

[0016] The method provided by the present invention and the prepared modified Prussian blue analogue cathode material have the following beneficial effects:

[0017] (1) During the modification process, under the action of low-temperature heating, the crystal water in the material can be removed during spray drying, reducing the water content in the material. At the same time, the conductive agent is interwoven to form a 3D space to encapsulate the dehydrated Prussian blue analog particles, obtaining a composite material with low crystal water content and high air stability. The reduction of the crystal water content in the material is conducive to reducing the adverse effects of crystal water on the stability of the organic electrolyte during charge and discharge.

[0018] (2) This process can directly obtain dry, clean material powder in one step, avoiding the tedious secondary drying process, shortening time, reducing costs, and facilitating scale-up. In addition, since the entire drying process is carried out dynamically, the particle agglomeration and compaction phenomena of conventional static drying (vacuum drying, etc.) are avoided, which is conducive to maintaining the material structure.

[0019] (3) The present invention uses a modifier with excellent conductive properties to enhance the conductivity of the material.

[0020] (4) Sodium ion batteries prepared using this type of material as the positive electrode have a relatively long cycle life. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a comparative XRD graph of a series of FeMn-PBA and FeMn-PBA@conductive agent materials of Examples 1-2.

[0022] FIG2 is a TG comparison chart of the series of FeMn-PBA and FeMn-PBA@conductive agent materials of Examples 1-2.

[0023] FIG3 is a FTIR comparison chart of the series of FeMn-PBA and FeMn-PBA@conductive agent materials of Examples 1-2.

[0024] FIG4 is a Raman comparison chart of the series of FeMn-PBA and FeMn-PBA@conductive agent materials of Examples 1-2.

[0025] FIG5 is a SEM image of the FeMn-PBA material of Example 1.

[0026] Figure 6 SEM image of the FeMn-PBA@conductive agent material of Example 2.

[0027] FIG7 is a dQ / dV comparison diagram of the series of FeMn-PBA and FeMn-PBA@conductive agent materials of Examples 1-2.

[0028] Figure 8 shows the FeMn-PBA and FeMn-PBA@conductive agent series of Examples 1-2 at 100 mA g -1 Comparison of cycling performance under different current densities.

[0029] FIG9 is a charge-discharge curve diagram of the FeMn-PBA@conductive agent material of Example 2.

[0030] FIG10 is a charge-discharge curve diagram of the FeMn-PBA@conductive agent material of Example 3. DETAILED DESCRIPTION

[0031] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are all commercially available unless otherwise specified.

[0032] Example 1

[0033] (1) Material preparation: Dissolve ferrous sulfate (4 mmol) and manganese sulfate (1 mmol) in 100 ml of deionized water and stir for 3 h, which is called solution A. Dissolve sodium ferrocyanide (5 mmol) in 100 ml of deionized water and stir for 3 h, which is called solution B. Pour solution A into solution B quickly, stir for 6 h, and age for 24 h. Then wash the lower precipitate with water and ethanol, and place it at 120 oAfter vacuum drying in a vacuum drying oven at 4000 nm for 12 h, the manganese-based Prussian blue analogue (denoted as FeMn-PBA) containing crystalline water and defects was collected.

[0034] (2) Preparation of electrodes: The FeMn-PBA material, conductive carbon black (conductive agent) and sodium alginate (binder) in step (3) were mixed at a ratio of 70:20:10 (wt%). The resulting mixture was transferred to a shaking tube, and 6 3 mm zirconium dioxide beads were added and shaken thoroughly to obtain a uniform slurry. The slurry was evenly coated on aluminum foil using a coater and placed in a vacuum drying oven at 80 °C for 12 h to allow the solvent to evaporate completely. The electrode was then cut into circular pieces with a diameter of 10 mm using a cutting machine. The pieces were weighed and the mass of the active material was calculated to be approximately 1.5 mg.

[0035] (3) The negative electrode was a 12 mm diameter circular sodium metal sheet. The electrolyte was a solution of NaClO₄ dissolved in ethyl methyl carbonate and propylene carbonate (volume ratio 1:1) with a 5 wt% fluoroethylene carbonate additive, where the NaClO₄ concentration was 1 mol / L. The separator was a glass fiber membrane (manufactured by Whatman).

[0036] (4) Electrochemical performance test: All battery assemblies were completed in a glove box (O wt% ≤ 0.01, H2O wt% ≤ 0.01). The constant current charge-discharge test and long cycle test of R2032 button cell were performed by Neware CT4000. The test voltage window was 2-4.0 V and the current density was 1C = 100 mA g. -1 .

[0037] Example 2

[0038] (1) The preparation process of the manganese-based Prussian blue analogue containing crystalline water and defects (denoted as FeMn-PBA) obtained in this example is the same as that in Example 1.

[0039] (2) The FeMn-PBA and graphene composite conductive agent obtained, with the conductive agent ratio being 2%, was weighed according to the mass ratio. 98 g of FeMn-PBA and 2 g of graphene were weighed respectively. The weighed materials were added to a beaker and stirred with a magnetic stirrer for 3 hours using 400 ml of ethanol as the solvent. After mixing evenly, the mixture was spray-dried using a spray dryer. The feed temperature during spray drying was set to 200 °C, the outlet temperature was 120 °C, and the feed rate was 50 ml / h. After spray drying, a dry iron-manganese-based Prussian blue analogue (denoted as FeMn-PBA@conductive agent) was obtained.

[0040] (3) The obtained FeMn-PBA@conductive agent composite positive electrode material was used as the positive electrode active material of the sodium ion battery. The FeMn-PBA material, conductive carbon black (conductive agent) and sodium alginate (binder) in step (2) were mixed according to 70:20:10 (wt%), and ultrapure water was used as a dispersant; 6 3 mm zirconium dioxide beads were added and shaken thoroughly to obtain a uniform slurry, which was evenly coated on aluminum foil using a coater and placed in a vacuum drying oven at 80 °C for 12 h to allow the solvent to evaporate completely. Then, a cutting machine was used to cut into circular electrodes with a diameter of 10 mm, which were weighed and the mass of the active material was calculated to be ~1.5 mg.

[0041] (4) The negative electrode sheet was a 12 mm diameter circular sodium metal sheet. The electrolyte was a solution of NaClO₄ dissolved in ethyl methyl carbonate and propylene carbonate (volume ratio 1:1) with a 5 wt% fluoroethylene carbonate additive, where the NaClO₄ concentration was 1 mol / L. The separator was a glass fiber membrane (produced by Whatman), separating the positive and negative electrodes.

[0042] (5) Electrochemical performance test: All battery assemblies were completed in a glove box (O wt% ≤ 0.01, H2O wt% ≤ 0.01). Constant current charge-discharge test and long cycle test of R2032 button cell were performed by Neware CT4000. The test voltage window was 2-4.0 V and the current density was 1C = 100 mA g. -1 .

[0043] Example 3

[0044] (1) The preparation process of the manganese-based Prussian blue analogue containing crystalline water and defects (denoted as FeMn-PBA) obtained in this example is the same as that in Example 1.

[0045] (2) The FeMn-PBA and graphene composite conductive agent obtained, with the conductive agent ratio being 5%, were weighed according to the mass ratio. 95 g of FeMn-PBA and 5 g of graphene were weighed respectively. The weighed materials were added to a beaker and stirred with a magnetic stirrer for 3 hours using 400 ml of ethanol as the solvent. After mixing evenly, the mixture was spray-dried using a spray dryer. The feed temperature during spray drying was set to 200 °C, the outlet temperature was 120 °C, and the feed rate was 50 ml / h. After spray drying, a dry iron-manganese-based Prussian blue analogue was obtained.

[0046] (3) The obtained FeMn-PBA@conductive agent composite positive electrode material was used as the positive electrode active material of the sodium ion battery. The FeMn-PBA material, conductive carbon black (conductive agent) and sodium alginate (binder) in step (2) were mixed according to 70:20:10 (wt%), and ultrapure water was used as a dispersant; 6 3 mm zirconium dioxide beads were added and shaken thoroughly to obtain a uniform slurry, which was evenly coated on aluminum foil using a coater (MSK-AFA-I) and placed in a vacuum drying oven at 80 °C for 12 h to allow the solvent to evaporate completely. Then, a cutting machine (MSK-T10) was used to cut the circular electrode pieces with a diameter of 10 mm, which were weighed and the mass of the active material was calculated to be ~1.5 mg.

[0047] (4) Sodium metal was used as the negative electrode. The assembled button cell was completed in a glove box (O wt% ≤ 0.01, H2O wt% ≤ 0.01). The constant current charge-discharge test and long cycle test of the R2032 button cell were achieved by Neware CT4000. The test voltage window was 2-4.0 V and the current density was 1C = 100 mA g -1 .

[0048] Example 4

[0049] (1) The preparation process of the manganese-based Prussian blue analogue containing crystalline water and defects (denoted as FeMn-PBA) obtained in this example is shown in Example 1.

[0050] (2) The FeMn-PBA and graphene composite conductive agent obtained, with the conductive agent ratio being 2%, were weighed according to the mass ratio. 100 g of FeMn-PBA and 2 g of graphene were weighed respectively. The weighed materials were added to a beaker and stirred with a magnetic stirrer for 3 hours using 400 ml of ethanol as the solvent. After mixing evenly, the mixture was spray-dried using a spray dryer. The feed temperature during spray drying was set to 200 °C, the outlet temperature was 100 °C, and the feed rate was 50 ml / h. After spray drying, a dry iron-manganese-based Prussian blue analogue was obtained.

[0051] (3) Electrode preparation was the same as in Example 1, with sodium metal as the negative electrode. The assembled button cell was completed in a glove box (O wt% ≤ 0.01, H2O wt% ≤ 0.01). The constant current charge-discharge test and long cycle test of the R2032 button cell were performed using a Neware CT4000. The test voltage window was 2-4.0 V, and the current density was 1C = 100 mA g -1 .

[0052] Example 5

[0053] (1) The FeMn-PBA and graphene composite conductive agent obtained in Example 1 were weighed according to the mass ratio. The conductive agent ratio was 2%. 100 g of FeMn-PBA and 2 g of graphene were weighed respectively. The weighed materials were added to 20 beakers. 400 ml of ethanol was used as the solvent. The mixture was stirred with a magnetic stirrer for 3 hours. After mixing evenly, it was spray-dried using a spray dryer. The feed temperature during spray drying was set to 200 ° C, the outlet temperature was set to 120 ° C, and the feed rate was set to 50 ml / h. After spray drying, a dry iron-manganese-based Prussian blue analogue was obtained.

[0054] (2) The material of step (2) in Example 2 was obtained, 3 g of the material to which 2% graphene composite conductive agent was added was weighed and placed in a corundum boat, which was then placed in a tubular furnace in a nitrogen atmosphere and heated to 180 °C at a heating rate of 5 °C / min and kept warm for 6 h to obtain a positive electrode material.

[0055] (3) Electrode preparation was the same as in Example 1, with sodium metal as the negative electrode. The assembled button cell was completed in a glove box (O wt% ≤ 0.01, H2O wt% ≤ 0.01). The constant current charge-discharge test and long cycle test of the R2032 button cell were performed using a Neware CT4000. The test voltage window was 2-4.0 V, and the current density was 1C = 100 mA g -1 .

[0056] Example 6

[0057] (1) The FeMn-PBA and graphene composite conductive agent obtained in Example 1 were weighed according to the mass ratio. The conductive agent ratio was 2%. 100 g of FeMn-PBA and 2 g of graphene were weighed respectively. The weighed materials were added to a beaker and stirred with a magnetic stirrer for 3 hours using 400 ml of ethanol as a solvent. After mixing evenly, the mixture was spray-dried using a spray dryer. The feed temperature during spray drying was set to 200 °C, the outlet temperature was 120 °C, and the feed rate was 50 ml / h. After spray drying, a dry iron-manganese-based Prussian blue analog (denoted as FeMn-PBA@conductive agent) was obtained.

[0058] (2) The material of step (2) in Example 2 was obtained, 3 g of the material to which 2% graphene composite conductive agent was added was weighed and placed in a corundum boat, which was then placed in a tubular furnace in a nitrogen atmosphere and heated to 180°C at a heating rate of 3°C / min and kept warm for 6 h to obtain a positive electrode material.

[0059] (3) Electrode preparation was the same as in Example 1, with sodium metal as the negative electrode. The assembled button cell was completed in a glove box (O wt% ≤ 0.01, H2O wt% ≤ 0.01). The constant current charge-discharge test and long cycle test of the R2032 button cell were performed using a Neware CT4000. The test voltage window was 2-4.0 V, and the current density was 1C = 100 mA g -1 .

[0060] Example 7

[0061] (1) The preparation process of the manganese-based Prussian blue analogue containing crystalline water and defects (denoted as FeMn-PBA) obtained in this example is shown in Example 1.

[0062] (2) The FeMn-PBA obtained in step (1) was mixed with carbon nanotubes, with the ratio of carbon nanotubes being 2%. That is, 19.8 g of FeMn-PBA and 0.2 g of carbon nanotubes were weighed and added to a beaker, and 100 ml of ethanol was added and magnetic stirring was performed for 3 h. After stirring evenly, spray drying was performed. The feed temperature and outlet temperature were the same as those in step (2) of Example 2. The obtained material was recorded as FeMn-PBA / conductive agent.

[0063] (3) Electrode preparation was the same as in Example 1, with sodium metal as the negative electrode. The assembled button cell was completed in a glove box (O wt% ≤ 0.01, H2O wt% ≤ 0.01). The constant current charge-discharge test and long cycle test of the R2032 button cell were performed using a Neware CT4000. The test voltage window was 2-4.0 V, and the current density was 1 C = 100 mA g -1 .

[0064] FIG1 is a comparison diagram of the XRD patterns of the two products of Examples 1-2. It can be seen that the composite material retains its original monoclinic structure after spray drying, and the peak intensity is weakened, which may be caused by the graphene / carbon nanotube composite water-based conductive agent coating the surface of the material.

[0065] Figure 2 is a TGA comparison chart of FeMn-PBA and FeMn-PBA@conductive agent materials of Example 1-2. The modification treatment effectively removes the crystalline water in the unmodified Prussian blue sodium cathode material and simultaneously performs surface coating. The lowest water content of the composite material can be controlled at about 8.1% of the total weight of the material.

[0066] Figure 3 is a FTIR comparison of the two materials of Example 1-2. The composite material has the following wavelengths at 1618 and 3537 cm -1 The peak intensities of OHO and OH are slightly weakened, which further proves the reduction of water content in the material.

[0067] Figure 4 is a Raman comparison of the two materials in Example 1-2. It can be seen that the spray-dried material has a Raman wavelength of 1335 cm -1 ,1608 cm -1 The appearance of weak peaks can be attributed to the D and G peaks formed by the coated carbon material, and the peak intensity of Fe-CN becomes weaker and slightly shifts to the right, which may be because the carbon coating layer weakens the -CN signal.

[0068] FIG5 is a SEM image of the FeMn-PBA material of Example 1. It can be seen that the FeMn-PBA material is in the form of large blocks formed by agglomeration of primary particles of about 1 μm.

[0069] FIG6 is a SEM image of the FeMn-PBA@conductive agent material of Example 2. After spray drying, the graphene evenly wraps the particles into spheres of varying sizes.

[0070] FIG7 is a dQ / dV comparison diagram of the two materials in Example 1-2. There is no significant change in the redox potential of the active material before and after modification.

[0071] Figure 8 shows the two materials in Example 1-2 at 100 mA g -1 From the comparison of cycling performance under current density, it can be seen that after spray drying, the capacity does not decrease significantly, and the cycling stability is improved to a certain extent. This is mainly attributed to the conductive coating layer improving the conductivity of the composite material and improving the interface stability during the cycle.

[0072] Figure 9 is a charge-discharge curve of the FeMn-PBA@conductive agent material of Example 2. -1 It can be seen that after 100 cycles, the current remains at 111.1 mA g -1 Specific capacity retention (corresponding capacity retention rate is 84.47%).

[0073] Figure 10 is a charge-discharge curve of the FeMn-PBA@conductive agent material of Example 3. -1 It can be seen that after 100 cycles, 104.4 mA g -1 Specific capacity retention (corresponding capacity retention rate is 82.27%).

Claims

1. A method for modifying a Prussian blue analog sodium cathode material, characterized in that: The following steps are involved: (1) A conductive agent as a coating agent and a dehydrating agent is mixed with a Prussian blue analogue in a certain proportion using ethanol as a solvent in a beaker to form a uniform slurry; (2) feeding the uniform slurry in step (1) at a certain peristaltic speed through a peristaltic pump and spray drying at a certain inlet temperature and outlet temperature; (3) After the solution in step (2) is spray-dried, the material therein is collected and stored in a vacuum.

2. The coating agent in step (1) according to claim 1 is one or more of the conductive agents selected from the group consisting of graphene / carbon nanotube composites, aniline, pyrrole, acrylonitrile, polyacrylonitrile, polyaniline, phenolic resin, and asphalts with different softening points.

3. The Prussian blue analogue of step (1) according to claim 1 is a Prussian blue containing crystal water and defects, which is a hydrated and defective iron-based Prussian blue material, a hydrated and defective iron-manganese-based Prussian blue material, a hydrated and defective iron-cobalt-based Prussian blue material, a hydrated and defective iron-nickel-based Prussian blue material, a hydrated and defective iron-copper-based Prussian blue material, a hydrated and defective iron-zinc-based Prussian blue material, a hydrated and defective manganese-based Prussian blue analogue, One or more of hydrated and defective manganese-cobalt-based Prussian blue materials, hydrated and defective manganese-nickel-based Prussian blue materials, hydrated and defective manganese-copper-based Prussian blue materials, hydrated and defective zinc-manganese-based Prussian blue materials, hydrated and defective nickel-based Prussian blue materials, hydrated and defective zinc-based Prussian blue analogs, hydrated and defective cobalt-based Prussian blue analogs, hydrated and defective vanadium-based Prussian blue analogs and hydrated and defective cerium-based Prussian blue analogs.

4. According to claim 1, it is characterized in that: In the steps, the feed temperature of the small-scale spray dryer is 100-300°C, the outlet temperature is 100-250°C, and the feed rate is 50-200 ml / h.

5. According to the Prussian blue-based sodium ion battery positive electrode material of claim 1, the content of the coating agent in the step (1) accounts for 1%-20%.

6. A sodium ion battery energy storage device, comprising: A positive electrode sheet comprises a positive electrode current collector and a positive electrode slurry loaded on the current collector, a negative electrode sheet and a separator. Characterized in that the positive electrode material comprises a Prussian blue sodium ion battery positive electrode material obtained by the preparation method according to any one of claims 1 to 5.

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