Positive electrode material for sodium batteries and its manufacturing method

Abstract

To provide a positive electrode material for a sodium battery and a manufacturing method thereof, which can facilitate processing and at the same time improve battery capacity.SOLUTION: A cathode material is sodium iron manganese titanium silicate coated with a carbon layer, and the molecular formula of sodium iron manganese titanium silicate is NaqFexMny(TiO2)z(SiO4)m, where 1.5≤q≤2.5, 0.7≤x≤0.8, 0.2≤y≤0.3, 0.07≤z≤0.5, and 0.5≤m≤1.5 are satisfied. A method for manufacturing the cathode material includes a step (1) of mixing and calcining an iron source, a manganese source, a sodium source, and a solvent to obtain a precursor, and a step (2) of mixing the precursor with a silicate ester, a titanate, and an organic solvent to obtain a mixture, and calcining the mixture in the presence of an organic substance to obtain a sodium battery cathode material.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This application claims priority to a Chinese patent application filed on March 21, 2023, bearing application number 202310280551.7, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to the technical field of cathode materials for sodium batteries, and more particularly to cathode materials for sodium batteries and methods for producing the same. [Background technology]

[0003] In recent years, sodium-ion batteries have attracted considerable attention due to their abundant sodium resources and similar operating principles to lithium-ion batteries. They are a promising new energy storage technology that promises to promote low-cost application and sustainable development. Polyanionic compounds have been widely studied as high-performance and safe cathode materials, and their strong covalent bonds in their structure provide a stable framework, effectively improving the safety of electrodes during charging and discharging.

[0004] However, currently reported polyanion-type positive electrodes have difficulty achieving multi-electron reactions under the conditions of a single polyanion group, significantly limiting their energy utilization. Taking sodium iron silicate (Na2FeSiO4) as an example, it is theoretically capable of two-electron reactions and has a high theoretical capacity of 276 mAh / g. However, due to the low intrinsic electronic conductivity of Na2FeSiO4, the charge exchange process within the electrode is slow. Therefore, within the safe voltage window of the electrolyte, Na2FeSiO4 positive electrodes cannot achieve multi-electron reactions, resulting in a significantly lower actual capacity than the theoretical capacity.

[0005] Professor Jiang Yinzhu of Zhejiang University and his colleagues designed the structural framework of sodium iron silicate and selected fluorine ions as a modifier to replace oxygen sites. Kinetics-wise, fluorine ions can break the local charge balance in the Na2FeSiO4 structure and increase the electron transfer pathways, thus promoting charge transfer. Thermodynamically, the introduction of fluorine can enhance the charge transfer of Fe 4+ To stabilize the intermediate phase containing Fe 3+ / Fe 4+ This is the first time that it has been demonstrated that the fluorine-substituted sodium iron silicate cathode (NFSF) produced by this research can promote redox reactions. The specific capacity of the resulting cathode is high at 271 mAh / g, enabling a complete and reversible two-electron reaction. However, the manufacturing process in the paper is relatively complicated, making it difficult to commercialize. Summary of the Invention

[0006] In view of this, the present invention aims to provide a cathode material for sodium batteries and a manufacturing method thereof, which is doped with titanium and manganese and coated with carbon, which can facilitate processing and improve the capacity of subsequent batteries.

[0007] To achieve the above objectives, the present invention uses the following technical solutions:

[0008] A cathode material for a sodium battery, which is sodium iron manganese titanium silicate coated with a carbon layer, and the molecular formula of the sodium iron manganese titanium silicate is Na q Fe x Mn y( TiO2) z (SiO4) m where 1.5≦q≦2.5, 0.7≦x≦0.8, 0.2≦y≦0.3, 0.07≦z≦0.5, and 0.5≦m≦1.5.

[0009] The specific surface area of ​​the positive electrode material for sodium batteries of the present invention is 15-25 m 2 / g, preferably 19.75m 2 / g, the resistivity of the powder is 8-12 Ω cm, preferably 9.5 Ω cm, the D50 particle size of the positive electrode material for sodium batteries is 7-10 μm, preferably 7.8 μm, and the D90 particle size of the positive electrode material for sodium batteries is 20-30 μm, preferably 25.3 μm.

[0010] The tap density of the positive electrode material for a sodium battery of the present invention is 1-2 g / mL, preferably 0.95 g / mL;

[0011] The compressed density is 1-3 g / mL, preferably 2.15 g / mL; The thickness of the carbon layer is 2-3 nm, preferably 2.5 nm.

[0012] The molecular formula of the sodium iron manganese titanium silicate of the present invention is Na q Fe x Mn y Ti z (SiO4) m where 1.5≦q≦2.5, 0.7≦x≦0.8, 0.2≦y≦0.3, 0.07≦z≦0.5, 0.5≦m≦1.5, and preferably 1.8≦q≦2.0, 0.095≦z≦0.285, 0.665≦m≦0.855.

[0013] The molecular formula of the positive electrode material for sodium batteries of the present invention is Na q Fe x Mn y( TiO2) z (SiO4) m / C, where 1.5≦q≦2.5, 0.7≦x≦0.8, 0.2≦y≦0.3, 0.07≦z≦0.5, 0.5≦m≦1.5, and preferably 1.8≦q≦2.0, 0.095≦z≦0.285, 0.665≦m≦0.855.

[0014] In one embodiment of the present invention, the molecular formula of the sodium iron manganese titanium silicate is Na 1.97 Fe 0.77 Mn 0.25( TiO2) 0.25 (SiO4) 0.77The molecular formula of the positive electrode material for sodium batteries is Na 1.97 Fe 0.77 Mn 0.25( TiO2) 0.25 (SiO4) 0.77 / C.

[0015] The present invention further provides a method for producing a cathode material for a sodium battery, the method comprising: (1) mixing an iron source, a manganese source, a sodium source, and a solvent and calcining the mixture to obtain a precursor; and (2) mixing the precursor with a silicate ester, a titanate, and an organic solvent to obtain a mixture, and calcining the mixture in the presence of an organic substance to obtain a positive electrode material for a sodium battery.

[0016] In the present invention, the molar ratio of the iron source to the manganese source to the sodium source is 1:(0.1-1):(5-10), preferably 1:(0.1-0.5):(7-10), and more preferably 1:0.45:7.

[0017] The mass ratio of the total mass of the iron source, manganese source, and sodium source to the solvent is 1:(5-10), preferably 1:(4-8), and more preferably 1:6.

[0018] In the present invention, the molar ratio of sodium in the precursor to silicon in the silicate ester to titanium in the titanate is 2:(0.7-0.9):(0.1-0.3), preferably 2:0.8:0.25, and the mass ratio of the precursor to the organic solvent is 1:(1-10), preferably 1:(3-5), more preferably 1:4.

[0019] In step (2), the mass ratio of the organic material to the mixture is 1:(0.02-0.05), and the organic material is preferably in the form of gas during the calcination process, preferably n-propyl alcohol gas. The vapor deposition method can more uniformly coat the carbon on the surface of the sodium iron manganese titanium silicate.

[0020] In step (1) of the present invention, the precursor, the silicate ester, the titanate and the organic solvent are mixed to obtain a mixture, and the mixture is preferably pulverized, the pulverization method is pulverization until the particle size reaches 130 nm, and the pulverization temperature is ≦45°C.

[0021] Before the calcination, it is preferable to dry the mixture obtained by mixing the iron source, the manganese source, the sodium source, and the solvent, and the drying is preferably spray drying.

[0022] The sodium source is one or more of sodium nitrate, sodium hydroxide, sodium carbonate, sodium oxalate, sodium nitrite, disodium hydrogen phosphate, sodium bicarbonate, sodium citrate, anhydrous sodium sulfate, sodium stearate, sodium oleate, sodium tartrate, sodium alginate, sodium carboxymethylcellulose or sodium lactate, preferably sodium nitrate.

[0023] The iron source is one or more of iron nitrate, iron citrate, iron stearate, iron oleate, iron tartrate, iron alginate, iron carboxymethylcellulose or iron lactate, preferably iron nitrate.

[0024] The manganese source is one or more of manganese nitrate, manganese citrate, manganese stearate, manganese oleate, manganese tartrate, manganese alginate, manganese carboxymethylcellulose or manganese lactate, preferably manganese nitrate.

[0025] The silicate ester is one or more of isopropyl orthosilicate, ethyl orthosilicate or trimethylsiloxysilicate, preferably isopropyl orthosilicate.

[0026] The phthalate ester is one or more of tetraisopropyl titanate, tetrabutyl titanate, or tetraethyl titanate, preferably tetraisopropyl titanate.

[0027] Nitrates have the property of being easily decomposable, and can significantly lower the reaction temperature and shorten the reaction time, thereby producing particles with a small primary particle size and improving the subsequent reaction activity.

[0028] In the step (1) of the present invention, the calcination temperature is 650-750°C, preferably 700°C, and the calcination time is 4-6 hours, preferably 5 hours. After the calcination is completed, the material is preferably cooled to a temperature of ≦80°C and then discharged. The calcination temperature increase rate is preferably 2.5°C / h.

[0029] The exhaust gases generated in the calcination process are preferably absorbed with sodium hydroxide solution to obtain a sodium nitrate solution which can be reused.

[0030] In the step (2) of the present invention, the calcination temperature is 620°C and the calcination time is 10-15 hours; The calcination is divided into a temperature-raising stage, a temperature-holding stage, and a temperature-lowering stage. During the temperature-raising process, the oxygen content in the furnace is maintained at less than 5 ppm, preferably by introducing nitrogen gas. The temperature-raising rate during the temperature-raising stage is 1.0-2.5°C / h. In the incubation stage, organic gas is introduced into the system, and the incubation time is 11-14 hours. In the cooling stage, the cooling rate is 1-1.5°C / h, and after the material temperature reaches ≦60°C, the cooling is stopped and the material is then discharged.

[0031] In one embodiment of the present invention, the organic gas is gaseous n-propyl alcohol, which is preheated to a vapor state.

[0032] In the present invention, the solvent is one or more of water, ethanol, and acetone, preferably water, and the organic solvent is one or more of ethanol, propanol, ethylene glycol, and acetone, preferably ethanol.

[0033] In the step (2) of the present invention, the mixture is dried to obtain a dried product; The drying is carried out in the presence of an inert gas, preferably nitrogen gas, and the temperature of the nitrogen gas is 330-350°C; the drying process is preferably spray drying, and the spray drying is preferably pressure spray drying, and the gas pressure of the spray drying is 8-12 atmospheres; and the intake volume per unit time is 800-2000 times the volume of the slurry introduced; After spray drying is completed, the spray-dried material and organic gas are introduced into a cyclone dust collection tower for solid-gas separation, and the solid matter is collected. The nitrogen gas and organic gas are filtered through a dust collection cloth bag and then condensed. The organic solvent is recovered, and the nitrogen gas is recycled.

[0034] In the present invention, the total mass of the organic gas introduced is 0.002-0.006 times, preferably 0.04 times, the mass of the spray-dried material.

[0035] In the step (2) of the present invention, it is preferable to pulverize the mixture before drying. Zirconia balls are used as the pulverizing medium, and the temperature is lowered with cooling water during the pulverization process, while the temperature of the organic solvent is maintained at 45°C or less, until the particle size of the slurry reaches 130 nm, thereby obtaining a pulverized product.

[0036] In the present invention, the manufacturing method further includes, in the step (2), mixing the calcined material with an adhesive and a diluent, and performing spray granulation to obtain a positive electrode material for a sodium battery; The crushed material is preferably sieved through an 80-150 mesh sieve, and the calcined material is crushed, after which the iron is removed by electromagnetic force, and then mixed with an adhesive and a diluent. When the content of magnetic substances is less than 1 ppm, the iron removal is stopped. The adhesive is polyurethane and the diluent is one or more of ethyl acetate, toluene, dimethylformamide, glycol ethers, and glycol esters.

[0037] The positive electrode material for sodium batteries obtained by the manufacturing method of the present invention has a particle size of 5-15 μm and a core-shell structure, with the inner core being iron manganese titanium sodium silicate, and the surface of the iron manganese titanium sodium silicate being uniformly coated with a 2-3 nm carbon layer.

[0038] The present invention further provides a battery comprising the above-mentioned positive electrode material for a sodium battery.

[0039] The present invention does not have any special requirements for the raw materials and manufacturing methods of other materials such as the negative electrode of the battery, and conventional raw materials and methods in this field can be used.

[0040] The beneficial effects of the present invention are as follows:

[0041] 1. A precursor is obtained by using an iron source, a manganese source, and a sodium source to produce a material in which manganese, iron, and sodium are uniformly mixed. Using a solution method, iron ions, sodium ions, and manganese ions can be mixed at the atomic level. This is then dried using a spray-drying method and calcined at high temperature. Since the size range involved in the mixing is relatively small, the ion migration distance can be significantly reduced.

[0042] 2. In the design of the cathode material for sodium batteries, silicate and titanium are incorporated into the present invention. The introduction of titanium can achieve titanium doping, thereby improving ionic conductivity and thereby capacity. Furthermore, the introduction of titanium can effectively consume the free sodium remaining on the surface of the material. Titanium and free sodium ions can form sodium titanate, which improves processing performance and further improves the capacity of the subsequent battery.

[0043] 3. This invention uses silicate ester and titanate as raw materials, which can be completely dissolved in an organic solvent. After mixing the silicate ester and titanate with a precursor and spray-drying, the mixture of precursor, silicate ester, and titanate crystallizes, resulting in more complete mixing and subsequent reaction. At the same time, the thermal decomposition of the alkyl groups in the organic material produces a carbon source, effectively limiting particle growth and resulting in a material with a small primary particle size. In terms of coating efficiency, this method improves the carbon coverage compared to the method using an additional carbon source, resulting in a more uniform primary particle size. At the same time, the dispersibility of the iron manganese titanium sodium silicate in an organic system is excellent, resulting in a more uniform primary particle size in the final product.

[0044] 4. In the present invention, during the pre-calcination stage, organic gas is introduced into the system by vapor deposition. When ferrous ions are present in the areas not covered with carbon, i.e., the ferrous ions are exposed to the outside, the organic gas is catalytically decomposed at these areas to form carbon, and the carbon adheres to these areas, further improving the uniformity of the carbon coating.

[0045] 5. In the spray drying stage, the particle size is controlled, and the final product is directly sieved without being crushed, so that spherical particles with a particle size of 5-15 μm can be formed. Spray drying can improve the solid content when homogenizing the slurry in the final processing process, thereby improving processing performance and reducing costs, while also improving the compaction density of the product. [Brief explanation of the drawings]

[0046] [Figure 1] FIG. 1 is an SEM image of the unground precursor after sintering in step (1) of Example 1. [Figure 2] FIG. 2 is an SEM image of the precursor after sintering and pulverization in step (1) of Example 1. [Figure 3] FIG. 1 is an SEM image of the positive electrode material for a sodium battery obtained in Example 1. [Figure 4] FIG. 2 is a transmission electron microscope image of the pulverized positive electrode material for a sodium battery obtained in Example 1. [Figure 5] 1 shows charge-discharge curves of the positive electrode material for a sodium battery obtained in Example 1. [Figure 6] 1 is a cycle curve of the positive electrode material for a sodium battery obtained in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0047] The technical solutions of the present invention will be described clearly and completely below with reference to the embodiments of the present invention. Of course, the described embodiments are only a part of the embodiments of the present invention, but are not all of the embodiments. Based on the embodiments of the present invention, any other embodiments that a person skilled in the art can come up with without any creative efforts fall within the scope of protection of the present invention.

[0048] To further illustrate the present invention, the following examples are provided in more detail. All raw materials used in the following examples of the present invention are commercially available products.

[0049] Electrochemical performance test: The compounding ratio (mass ratio) of the electrode pieces was electrode material: conductive graphite: PVDF = 87:8:5.

[0050] A CR2025 button battery was fabricated using metallic sodium as the reference electrode, with sodium flakes as the negative electrode and sodium hexafluorophosphate as the electrolyte. The button battery was left at room temperature (25°C) for 10 hours, after which it was charged and discharged to activate it. Then, a charge-discharge cycle test was performed on the button battery using a LANDEN battery charge-discharge tester.

[0051] First, at room temperature (25°C), one cycle is performed at 0.1C, then one cycle at 0.2C, then one cycle at 0.5C, and then one cycle at 1C, where the charge / discharge voltage range of the control battery is detected in a voltage window of 1.0-4.5V.

[0052] Other performance tests Method for measuring tap density: Take 50g of material and place it in a calibrated 100mL measuring cylinder. Then, set the amplitude to 2cm and vibrate 5000 times. The density obtained by calculation is the tap density.

[0053] Method for measuring compressed density: Use an electronic compressed density meter to take 1g of material, then put it into a mold and press it under 3T pressure for 30s, then calculate its density as the compressed density. [Example]

[0054] Example 1

[0055] (1) Iron nitrate, manganese nitrate, and sodium nitrate were mixed in a mass ratio of 0.75:0.25:1.9, and pure water was added to dissolve and mix uniformly. The mass ratio of the total mass of iron nitrate, manganese nitrate, and sodium nitrate to pure water was 1:6. The mixture was then spray-dried to obtain a spray material. The temperature was increased to 700°C at a rate of 2.5°C / h and calcined for 5 hours. The material was then cooled to a temperature of ≦80°C and discharged. The exhaust gas generated during the calcination process was absorbed with sodium hydroxide solution to obtain a sodium nitrate solution, which was then recycled. The precursor obtained by the method in step (1) was a mixture of iron nitrate, manganese nitrate, and sodium nitrate. The precursor's main components were a mixture of iron nitrate, manganese nitrate, and sodium nitrate. The precursor's performance data are shown in Table 1. SEM images of the precursor before and after milling are shown in Figures 1 and 2, respectively.

[0056] [Table 1]

[0057] (2) Mix the precursor with isopropyl orthosilicate and tetraisopropyl titanate, the molar ratio of sodium in the precursor to silicon in the silicate ester and titanium in the titanate being 2:0.8:0.25, add ethanol solvent, the mass ratio of precursor to ethanol being 1:4, put it into a sand grinder and grind it, using zirconia balls as grinding medium, cooling it with cold water during the grinding process, keeping the temperature of the organic solvent below 45°C, grinding until the particle size of the slurry is 130 nm, and obtain a ground product.

[0058] (3) The pulverized material is pressure spray dried. In the spray drying, nitrogen gas is used as a heating medium, and the nitrogen gas is heated to 330°C. The nitrogen gas is then introduced into the spray drying tower to dry the spray droplets and gasify the organic solvent. The spray-dried material and the organic gas are then introduced into a cyclone dust collection tower for solid-gas separation, and the solid matter is collected. The nitrogen gas and the organic gas are filtered through a dust collection cloth bag, and then condensed to recover the organic solvent. The nitrogen gas is then recycled. In the spray drying process, the gas pressure is 9 atmospheres, and the intake volume per unit time is 1500 times the volume of the slurry introduced. The spray-dried material produced in the above steps is obtained, and the D50 particle size of the spray-dried material is 9.2 μm.

[0059] (4) The spray-dried material is placed in an atmospheric furnace and calcined. The calcination is divided into a heating stage, a temperature-holding stage, and a temperature-lowering stage. During the temperature-holding stage of the calcination process, nitrogen gas is introduced to maintain the oxygen content in the furnace at less than 5 ppm. The heating rate during the heating stage is 1.3°C / h, and the temperature is then raised to 620°C. The calcination is then maintained at this temperature for 13 hours. The temperature is then lowered at a temperature-lowering rate of 1.4°C / h. After the material temperature is lowered to 60°C or less, the cooling is stopped and the material is then discharged. During the temperature-holding stage, n-propyl alcohol is introduced into the system, and n- Propyl alcohol was heated to a vapor state in advance, and an organic gas pipe was inserted into the bottom of the charging sagger in the atmosphere furnace. The total mass of the organic gas introduced was 0.04 times the mass of the spray-dried material. After cooling, the material was crushed and passed through a 125 mesh sieve. Electromagnetic de-ironization was stopped until the magnetic substance content was less than 0.87 ppm. Then, polyurethane adhesive and ethyl acetate were mixed, and the mixture was directly spray-granulated without crushing to obtain a spherical carbon-coated sodium battery cathode material, with the molecular formula Na 1.97 Fe 0.77 Mn 0.25( TiO2) 0.25 (SiO4) 0.77 The powdered sodium battery cathode material was tested using a transmission electron microscope, and the results are shown in Figure 4. It can be seen that the surface of the sodium iron manganese titanium silicate was coated with a carbon layer of about 2.5 nm, and the carbon layer was uniformly coated.

[0060] The positive electrode material for sodium batteries of the present invention was assembled into a battery, and the charge / discharge curve was as shown in FIG. 5, and the cycle curve was as shown in FIG.

[0061] [Table 2]

[0062] The data show that the material of the present invention has very high capacity and long cycle life.

[0063] Comparison 1

[0064] Referring to the steps and condition parameters in Example 1, the precursor obtained in step (1) is mixed with silicon dioxide and titanium dioxide, and ethanol is added, and a subsequent test is carried out, in which the molar ratio of sodium in the precursor, silicon in the silicon dioxide and titanium dioxide, and titanium in the titanate is 2:0.8:0.25. The performance test results of the product obtained in this comparative example are shown in Table 3 below. It can be seen that the positive electrode material for sodium ion batteries manufactured from the raw materials not only has a significantly reduced first discharge efficiency, but also a significantly reduced capacity retention rate at -20°C and room temperature.

[0065] [Table 3]

[0066] The description of the disclosed embodiments above will enable those skilled in the art to make or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. The sodium iron manganese titanium silicate is coated with a carbon layer, and the molecular formula of the sodium iron manganese titanium silicate is Na q Fe x Mn y (TiO 2 ) z (SiO 4 ) m wherein 1.5≦q≦2.5, 0.7≦x≦0.8, 0.2≦y≦0.3, 0.07≦z≦0.5, and 0.5≦m≦1.

5.

2. The specific surface area is 15-25m 2 2. The positive electrode material for a sodium battery according to claim 1, wherein the powder has a resistivity of 8-12 Ω·cm and a D50 particle size of 7-10 μm.

3. 2. The positive electrode material for a sodium battery according to claim 1, wherein the tap density is 1-2 g / mL, the pressed density is 1-3 g / mL, and the thickness of the carbon layer is 2-3 nm.

4. A method for producing the positive electrode material for a sodium battery according to claim 1, comprising: (1) mixing an iron source, a manganese source, a sodium source, and a solvent and calcining the mixture to obtain a precursor; and (2) mixing the precursor with a silicate ester, a titanate, and an organic solvent to obtain a mixture, and calcining the mixture in the presence of an organic substance to obtain a positive electrode material for a sodium battery.

5. 5. The method for producing a positive electrode material for a sodium battery according to claim 4, wherein the molar ratio of the iron source, the manganese source, and the sodium source is 1:(0.1-1):(5-10).

6. the molar ratio of sodium in the precursor to silicon in the silicate ester to titanium in the titanate is 2:(0.7-0.9):(0.1-0.3); 5. The method for producing a positive electrode material for a sodium battery according to claim 4, wherein the mass ratio of the organic material to the mixture is 1:(0.02-0.05).

7. the sodium source is one or more of sodium nitrate, sodium nitrite, sodium citrate, sodium stearate, sodium oleate, sodium tartrate, sodium alginate, sodium carboxymethylcellulose, or sodium lactate; the iron source is one or more of iron nitrate, iron citrate, iron stearate, iron oleate, iron tartrate, iron alginate, iron carboxymethylcellulose, or iron lactate; the manganese source is one or more of manganese nitrate, manganese citrate, manganese stearate, manganese oleate, manganese tartrate, manganese alginate, manganese carboxymethylcellulose, or manganese lactate; the silicate ester is one or more of isopropyl orthosilicate, ethyl orthosilicate, or trimethylsiloxysilicate; 5. The method for producing a positive electrode material for a sodium battery according to claim 4, wherein the titanate is one or more of tetraisopropyl titanate, tetrabutyl titanate, and tetraethyl titanate.

8. 5. The method for producing a positive electrode material for a sodium battery according to claim 4, wherein in step (1), the calcination temperature is 650-750°C and the calcination time is 4-6 hours, and in step (2), the calcination temperature is 620°C and the calcination time is 10-15 hours.

9. 5. The method for producing a positive electrode material for a sodium battery according to claim 4, wherein the step (2) further comprises mixing the calcined material with an adhesive and a diluent, followed by spray granulation to obtain the positive electrode material for a sodium battery.

10. A positive electrode material for a sodium battery according to any one of claims 1 to 3. Battery.

Images