Positive electrode material for single-crystal sodium-ion battery, manufacturing method for the same, positive electrode for sodium-ion battery, and sodium-ion battery

Abstract

To provide a positive electrode material for a single-crystal sodium-ion battery that possesses a single-crystal topography, exhibits excellent structural stability and integrity, prevents particle fracture during cycling, and improves the cycle stability of the sodium-ion battery.SOLUTION: The chemical composition formula of a positive electrode material for a single-crystal sodium-ion battery is Na1+aNi1-x-y-zMnxFeyMzO2, where -0.40≤a≤0.25, 0.08≤x≤0.5, 0.05≤y≤0.5, and 0≤z<0.26. The element M is one or more selected from Ti, Zn, Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, or Cu.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to the technical field of sodium ion batteries, and more particularly to a positive electrode material for a single crystal sodium ion battery, a method for producing the same, and a battery. [Background technology]

[0002] As the competition for lithium-ion batteries intensifies, the price of lithium salts is rising in addition to supply and demand relations and resource restrictions, and sodium-ion batteries, which have cost advantages, are gradually becoming the focus of research by major companies and universities. Sodium-ion batteries operate on the same principle as lithium-ion batteries, but compared to lithium-ion batteries, sodium ions have a larger ionic radius and a slower diffusion rate, so sodium ions have some disadvantages in terms of energy density and cycle characteristics.

[0003] After extensive research in various fields over the past decade, sodium-ion batteries have been developed into a system of products mainly consisting of transition metal oxides, Prussian blue, polyanion phosphates, etc. Among them, transition metal oxides have a relatively high specific capacity, making them popular. However, their poor cycle performance and low energy density are important factors affecting the application of positive electrode materials for sodium-ion batteries.

[0004] Transition metal oxides currently available on the market are primarily divided into two types: nickel-manganese-iron-copper oxides containing copper, and nickel-iron-manganese oxides. In either type, varying the ratio of nickel, iron, manganese, and copper elements can produce cathode materials for sodium-ion batteries with different performance characteristics. The different element ratios also affect the stability of the materials when in contact with the electrolyte. Factors that affect the cycle life of cathode materials for sodium-ion batteries are: 1) the restructuring of the surface crystalline structure during cycling; and 2) the destruction of agglomerated particles due to anisotropic volume expansion during cycling. Research has shown that the interparticle interconnection structure within agglomerated particles leads to localized increases in current density, which generates significant stress and thereby affects the cycling characteristics of the material. Furthermore, mismatches in the state of charge between different parts of the particles also affect the electrochemical performance of the electrode.

[0005] In addition, when the amount of desodium in the positive electrode material for sodium-ion batteries is relatively large, the structure becomes very fragile, and the active metals and oxygen in the lattice are displaced. At a certain high temperature and pressure, the atomic rearrangement and reorganization gradually intensifies, and the volume and material phase of the crystal grains change significantly. Meanwhile, when the positive electrode material is desodiumed, its oxidizing power becomes strong, and it is very easy to cause chemical and electrochemical reactions with the electrolyte, which makes the material easy to deoxidize, and the transition metals dissolve. Especially under high voltage, the electrolyte is oxidized, and H + is generated, which increases the acidity of the electrolyte, causing the surface film of the electrode material to be destroyed by HF, further changing the composition and structure of the interface, and seriously affecting the electrochemical and cycling performance of the material. Summary of the Invention [Problem to be solved by the invention]

[0006] The technical problem to be solved by the present invention is to provide a positive electrode material for a single crystal sodium ion battery that improves the cycle performance of the sodium ion battery.

[0007] In view of the above technical problems, the inventors of the present application have conducted extensive research and have obtained a single-crystal sodium ion battery positive electrode material with a single-crystal topography, which has a perfect structure, good processing performance, no particle cracking during cycling, and effectively reduces the occurrence of new interfaces caused by particle cracking. The crystalline structure of the material is stabilized, and when applied to sodium ion batteries, especially power-type sodium ion batteries, it can effectively improve the high-temperature, high-voltage cycling performance of the battery, especially its high-temperature stability. [Means for solving the problem]

[0008] The technical solutions of the present invention are as follows: The present invention provides a single-crystal sodium ion battery positive electrode material, the chemical composition formula of which is Na 1+a Ni 1-x-y-z Mn x Fe y M z O2, where -0.40≦a≦0.25, 0.08≦x≦0.5, 0.05≦y≦0.5, 0≦z<0.26; The M is one or more elements selected from Ti, Zn, Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, and Cu elements.

[0009] Preferably, −0.33≦a≦0, 0.10≦x≦0.5, and 0.15≦y≦0.5.

[0010] Preferably, M is one or more selected from Zn, Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, and Cu, and is preferably one or more selected from Zn, Al, B, Ti, Ca, Y, Mg, Nb, Zr, and Cu, and preferably satisfies the following ranges: -0.40≦a≦0.25, 0.08≦x≦0.5, 0.05≦y≦0.5, and 0≦z≦0.16.

[0011] Preferably, the monocrystalline sodium ion battery cathode material has a microscopic topography of monocrystalline topography under a scanning electron microscope, and the shape of the monocrystalline topography particles is preferably one or more of spherical, pseudo-spherical, polygonal, or layered sheet.

[0012] Preferably, in a powder X-ray diffraction spectrum (XRD) of the single crystal sodium ion battery positive electrode material, the full width at half maximum FWHM(110) of a (110) diffraction peak at a diffraction angle 2θ of around 64.9° is 0.06 to 0.35.

[0013] Preferably, the single crystal sodium ion battery positive electrode material has a green density of 2.8 to 4.2 g / cm under a pressure of 7000 to 9000 kg. 3 is.

[0014] Preferably, the water mass content of the monocrystalline sodium-ion battery cathode material is less than 3000 ppm, preferably less than 2800 ppm, more preferably less than 2500 ppm.

[0015] Preferably, the pH value of the monocrystalline sodium ion battery cathode material is within 13.1, preferably within 13.0.

[0016] Preferably, the specific surface area of ​​the single crystal sodium ion battery positive electrode material is 0.35 to 1.2 m 2 / g.

[0017] Preferably, the particle size D of the single crystal sodium ion battery positive electrode material V 50 is 2.0 to 16.0 μm, preferably 4.0 to 13.0 μm.

[0018] The present invention further provides a method for producing the above-mentioned single-crystal sodium-ion battery positive electrode material, which includes the steps of mixing raw materials including a sodium source compound, an iron source compound, and a manganese source compound, optionally adding a nickel source compound and / or an M source compound, sintering, and pulverizing the mixture to obtain a single-crystal topography sodium-ion battery positive electrode material.

[0019] Preferably, the sintering temperature is 860 to 990°C, preferably 880 to 980°C, and the isothermal time is preferably 6 to 40 hours.

[0020] Preferably, the grinding pressure is 0.1 to 1 MPa.

[0021] Preferably, the sodium source compound is one or more selected from the group consisting of sodium carbonate, sodium formate, sodium hydroxide, sodium acetate, sodium chloride, and sodium fluoride.

[0022] Preferably, the manganese source compound is one or more selected from the group consisting of dimanganese trioxide, trimanganese tetroxide, manganese oxide, manganese carbonate, manganese oxalate, manganese sulfate, manganese acetate, manganese chloride, and manganese nitrate.

[0023] Preferably, the nickel source compound is one or more selected from the group consisting of nickel carbonate, nickel oxalate, nickel sulfate, nickel acetate, nickel chloride, and nickel nitrate.

[0024] Preferably, the iron source compound is one or more compounds selected from the group consisting of ferric oxide, ferrous oxalate, ferric sulfate, ferric acetate, ferrous sulfate, ferrous acetate, ferrous nitrate, and ferric nitrate.

[0025] Preferably, the M source compound includes an oxide or salt containing the M element, and preferably, the M source compound includes one or more of calcium oxide, calcium hydroxide, diboron trioxide, boric acid, diniobium pentoxide, aluminum oxide, aluminum nitrate, aluminum acetate, titanium oxide, metatitanic acid, magnesium oxide, magnesium acetate, copper oxide, diyttrium trioxide, zirconium oxide, zirconium oxychloride, zirconium acetate, sodium fluoride, lithium fluoride, zinc oxide, and copper sulfate.

[0026] The present invention further provides a single-crystal sodium-ion battery positive electrode material produced by the above-mentioned production method.

[0027] The present invention further provides a positive electrode for a sodium ion battery, wherein the active material is the above-described single crystal sodium ion positive electrode material.

[0028] The present invention further provides a sodium ion battery comprising the above-described positive electrode for a sodium ion battery. The present invention further provides applications of the above-mentioned monocrystalline sodium ion battery cathode material, or the above-mentioned sodium ion battery cathode, or the above-mentioned sodium ion battery in photovoltaic power generation, wind power generation, smart grids, distributed power plants, home energy storage batteries, low-end motorcycle batteries, or low-energy density power batteries. [Effects of the Invention]

[0029] The beneficial effects of the present invention are as follows: The monocrystalline sodium-ion battery positive electrode material of the present invention has a specific chemical composition and monocrystalline topography, so that the monocrystalline sodium-ion battery positive electrode material has good structural stability and does not undergo significant structural changes due to frequent desorption of sodium ions during charging and discharging of the sodium-ion battery. Furthermore, the material has a perfect structure, good processing performance, and no particle cracking during cycling. This effectively prevents direct contact between the material surface and the electrolyte, especially with HF in the electrolyte, preventing side reactions and improving the cycling stability of the sodium-ion battery. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is an SEM image (magnification: 5000 times) of the single-crystal sodium ion battery positive electrode material produced in Example 1. [Figure 2] FIG. 2 is an SEM image (magnification: 5000 times) of the single-crystal sodium-ion battery positive electrode material produced in Example 2. [Figure 3] FIG. 3 is an SEM image (magnification: 5000 times) of the single-crystal sodium ion battery positive electrode material produced in Example 3. [Figure 4] FIG. 4 is an SEM image (magnification: 5000 times) of the single-crystal sodium ion battery positive electrode material produced in Example 4. [Figure 5] FIG. 5 is an SEM image (magnification: 5000 times) of the single-crystal sodium ion battery positive electrode material produced in Example 5. [Figure 6] FIG. 6 is an SEM image (magnification: 5000 times) of the single-crystal sodium ion battery positive electrode material produced in Example 6. [Figure 7] FIG. 7 is an SEM image (magnification: 5000 times) of a tab containing the single-crystal sodium-ion battery positive electrode material produced in Example 1. [Figure 8] FIG. 8 is an SEM image (magnification: 5000 times) of a tab containing the single-crystal sodium-ion battery positive electrode material produced in Example 2. [Figure 9] FIG. 9 is an SEM image (magnification: 5000 times) of a tab containing the single-crystal sodium-ion battery positive electrode material produced in Example 3. [Figure 10] FIG. 10 is an SEM image (magnification: 5000 times) of a tab containing the single-crystal sodium-ion battery positive electrode material produced in Example 4. [Figure 11] FIG. 11 is an SEM image (magnification: 5000 times) of a tab containing the single-crystal sodium-ion battery positive electrode material produced in Example 5. [Figure 12]FIG. 12 is an SEM image (magnification: 5000 times) of a tab containing the single-crystal sodium-ion battery positive electrode material produced in Example 6. [Figure 13] FIG. 13 is an SEM image (magnification: 5000 times) of the single-crystal sodium ion battery positive electrode material produced in Comparative Example 1. [Figure 14] FIG. 14 is an SEM image (magnification: 5000 times) of a tab containing the positive electrode material for a single crystal sodium ion battery produced in Comparative Example 1. [Figure 15] FIG. 15 is a cycle graph of the button batteries of Examples 1 to 6 and Comparative Example 1. [Figure 16] Figure 16 is an SEM image (magnification: 5000x) of the positive electrode tab of the BA-C1 battery after 50 cycles. DETAILED DESCRIPTION OF THE INVENTION

[0031] In order to clarify the purpose, technical solutions and technical effects of the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. The embodiments described below are only some of the embodiments of the present invention, but not all of the embodiments. All other embodiments obtained by those skilled in the art without performing creative work together with the embodiments of the present invention fall within the scope of protection of the present invention.

[0032] D of the present invention V 50 is the particle size corresponding to the percentage of the volume cumulative particle size distribution number in the sample reaching 50%.

[0033] In order to improve the cycling performance of sodium ion batteries, the present invention manufactures a positive electrode material for sodium ion batteries as single crystal particles, which improves the structural stability of the material, effectively inhibits structural changes, strengthens the reversibility of the material, and effectively avoids direct contact between the material and the electrolyte, especially the HF in the electrolyte, thereby preventing side reactions and inhibiting the crystalline phase transition of the material, thereby improving the cycling stability of the material.

[0034] In one specific embodiment of the present invention, the present invention provides a single-crystal sodium ion battery positive electrode material, and the chemical formula of the single-crystal topography sodium ion battery positive electrode material is Na 1+a Ni 1-x-y-z Mn x Fe y M z O2, where -0.40≦a≦0.25, 0.08≦x≦0.5, 0.05≦y≦0.5, 0≦z<0.26; The M is one or more elements selected from Ti, Zn, Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, and Cu elements.

[0035] In a preferred embodiment of the present invention, in the above Chemical Formula 1, −0.33≦a≦0, 0.1≦x≦0.5, and 0.15≦y≦0.5.

[0036] In a preferred embodiment of the present invention, M is one or more elements selected from Zn, Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, and Cu, and is preferably one or more elements selected from Zn, Al, B, Ti, Ca, Y, Mg, Nb, Zr, and Cu, and preferably satisfies 0≦z≦0.16.

[0037] In the present invention, the single-crystal sodium ion battery positive electrode material has a microscopic topography of single-crystal topography under a scanning electron microscope, and the shape of the single-crystal topography particles is one or more of spherical, pseudo-spherical, polygonal, and layered sheet.

[0038] In the present invention, in the powder X-ray diffraction spectrum (XRD) of the above-mentioned single crystal sodium ion battery positive electrode material, the full width at half maximum (FWHM(110)) of the (110) diffraction peak at a diffraction angle 2θ of around 64.9° (a diffraction angle around X° that appears in the present invention indicates that the diffraction angle is X°±1°, for example, around 64.9° indicates that the diffraction angle is 64.9°±1°, that is, 63.9° to 65.9°) is 0.06 to 0.35.

[0039] In the present invention, the green density of the single crystal sodium ion battery positive electrode material under a pressure of 7000 to 9000 kg is 2.8 to 4.2 g / cm 3 It is between.

[0040] In the present invention, the specific surface area of ​​the monocrystalline sodium ion battery positive electrode material is 0.35 to 1.2 m 2 / g.

[0041] In the present invention, the particle size D of the single crystal sodium ion battery positive electrode material V 50 is 2.00 to 16.0 μm, and preferably 4.0 to 13.0 μm.

[0042] The specific surface area (BET) of the single crystal sodium ion battery positive electrode material of the present invention is within a reasonable range, the intermolecular forces on the material surface are in a relatively balanced position, and self-aggregation is unlikely to occur even in a relatively humid environment.

[0043] The present invention further provides a method for producing the above-mentioned single-crystal sodium-ion battery positive electrode material, which includes the steps of mixing raw materials including a sodium source compound, an iron source compound, and a manganese source compound, optionally adding a nickel source compound and / or an M source compound, sintering the mixture, and pulverizing the mixture to obtain the single-crystal sodium-ion battery positive electrode material.

[0044] In the above-mentioned manufacturing method, the sintering is performed at a temperature of 860 to 990°C for 6 to 40 hours, and preferably, the sintering temperature is 880 to 980°C, and the atmosphere used for sintering is air, oxygen, or a mixed gas of air and oxygen; In the above production method, the grinding pressure is 0.1 to 1 MPa.

[0045] In the above production method, the sodium source compound includes a salt and / or hydroxide containing sodium element, such as one or more of sodium carbonate, sodium formate, sodium hydroxide, sodium acetate, sodium chloride, and sodium fluoride.

[0046] In the above-described production method, the manganese source compound includes an oxide, hydroxide, or salt containing manganese element, such as one or more of dimanganese trioxide, trimanganese tetroxide, manganese oxide, manganese carbonate, manganese oxalate, manganese sulfate, manganese acetate, manganese chloride, and manganese nitrate.

[0047] In the above production method, the nickel source compound includes a nickel-containing oxide, hydroxide, or salt, such as one or more of nickel carbonate, nickel oxalate, nickel sulfate, nickel acetate, nickel chloride, and nickel nitrate.

[0048] In the above-described production method, the iron source compound includes an oxide, hydroxide, or salt containing iron, such as one or more of ferric oxide, ferrous oxalate, ferric sulfate, ferric acetate, ferrous sulfate, ferrous acetate, ferrous nitrate, and ferric nitrate.

[0049] In the above production method, the M source compound includes an oxide and / or a salt containing the M element, and includes, for example, one or more of calcium oxide, calcium hydroxide, diboron trioxide, boric acid, diniobium pentoxide, aluminum oxide, aluminum nitrate, aluminum acetate, titanium oxide, metatitanic acid, magnesium oxide, magnesium acetate, copper oxide, diyttrium trioxide, zirconium oxide, zirconium oxychloride, zirconium acetate, sodium fluoride, lithium fluoride, zinc oxide, and copper sulfate.

[0050] The present invention further provides a positive electrode for a sodium ion battery, wherein the active material is the above-mentioned single-crystal sodium ion battery positive electrode material.

[0051] The present invention further provides a sodium ion battery comprising the above-described positive electrode for a sodium ion battery.

[0052] The sodium ion battery of the present invention further includes a negative electrode, an electrolyte containing a sodium salt, a separator, and an aluminum plastic film. Specifically, the positive electrode comprises a positive electrode current collector, a material including a positive electrode active material coated on the positive electrode current collector, a binder, a conductive additive, etc., and the positive electrode active material is the positive electrode material of the present invention. The negative electrode comprises a metallic sodium sheet or a current collector, a material including a negative electrode active material coated on the current collector, a binder, a conductive additive, etc., and the separator is a PP / PE film commonly used in the industry and is used to separate the positive electrode and negative electrode from each other, and the aluminum plastic film is a container for the positive electrode, negative electrode, separator, and electrolyte.

[0053] The binder in the present invention is primarily used to improve the binding properties between positive electrode active material particles and between the positive electrode active material particles and the current collector. The binder in the present invention can be selected from commercially available binders commonly used in the industry. Specifically, the binder may be selected from polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1,1-difluoroethylene, polyethylene, polypropylene, styrene-butadiene rubber, acrylated (esterified) styrene-butadiene rubber, epoxy resin, nylon, or a composition thereof.

[0054] The conductive additive in the present invention may be selected from commercially available conductive additives commonly used in the art. Specifically, the conductive additive may be selected from carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, or carbon fiber), metal-based materials (e.g., metal powders or metal fibers containing copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives), or compositions thereof.

[0055] The present invention further provides applications of the above-mentioned single-crystal sodium ion battery positive electrode material, or the above-mentioned sodium ion electrode, or the above-mentioned sodium ion battery in photovoltaic power generation, wind power generation, smart grid, distributed power plant, home energy storage battery, low-end motorcycle battery, or low-energy density power battery.

[0056] The beneficial effects of the present invention will be further illustrated below by specific examples.

[0057] All raw materials and reagents used in this invention were purchased from major manufacturers on the market. If the manufacturer or concentration is not specified, they are all commonly available analytical raw materials or reagents, and are not particularly limited as long as they achieve the desired effect. All instruments and equipment used in this example were purchased from major manufacturers on the market, and are not particularly limited as long as they achieve the desired effect. If specific techniques or conditions are not specified in this example, they are performed according to the techniques or conditions described in the literature in the relevant technical field or in accordance with the product instructions.

[0058] The raw materials and instruments used in the following examples and comparative examples are as shown in Table 1.

[0059] [Table 1]

[0060] [Table 2]

[0061] Example 1 The molar ratio of Na:Mn:Ni:Fe:B was 0.92:0.34:0.30:0.35:0.01, and the total weight was 1.63 kg. The corresponding weights of sodium carbonate, manganese carbonate, nickel carbonate, iron trioxide, and boric acid were weighed and mixed in an ultra-high-speed multi-function mixer at 3300 r / min for 20 minutes. The homogeneously mixed material was placed in a muffle furnace and heated to 885°C in an air atmosphere for 18 hours. Then, after natural cooling, it was pulverized in an airflow mill at a pulverization pressure of 0.60 MPa to obtain single-crystalline sodium-ion battery cathode material C1.

[0062] The cathode materials were characterized and analyzed according to the following methods. 1) Component analysis The components of the positive electrode material were analyzed using ICP. (1) Sample pretreatment Weigh 0.2000-0.2100g (accuracy from 0.001g) of sample into a 100mL quartz beaker, add 10mL of aqua regia (1:1) to the quartz beaker along the beaker wall, cover the surface dish, heat at 180°C for 30min, transfer the entire solution to a 50mL measuring flask, add deionized water to the volumetric solution and shake well, then aspirate 1mL of the solution from the well-shaken 50mL measuring flask into a 100mL measuring flask, add 5mL (25%) of nitric acid to the measuring flask, and add deionized water to the volumetric solution. (2) Component analysis tests were conducted using the calibration curve method. According to the above method, the single-crystal sodium ion battery positive electrode material C1 has the chemical formula Na 0.92 Ni 0.30 Mn 0.34 Fe 0.35 B 0.01 It was measured to be O2.

[0063] 2) Specific surface area The measurement was performed according to the national standard GB / T19587-2006, the method for measuring the specific surface area of ​​solids by gas adsorption BET method. Analytical instrument: Tristar II 3020 fully automatic specific surface area and pore distribution measuring device, Test parameters: adsorbate N2, 99.999%, coolant liquid nitrogen, P0 actual measurement, volume measurement mode, adsorption pressure deviation 0.05 mmHg, equilibration time 5 s, relative pressure point selection P / P0: 0.05, 0.1, 0.15, 0.2, 0.25, 0.30, Sample preparation: An empty sample tube and plug were weighed, and 3.8-4.2 g of sample was added to a 9.5 mm specific surface area sample tube with a 3 / 8 inch ball valve. The tube was heated to 200 °C using a FlowPrep 060 degassing station, purged with inert gas, and degassed for 0.5 h. The tube was then removed and cooled to room temperature. The combined sample tube, plug, and sample mass, M2, was weighed. The sample mass, M = M2 - M1, was then measured on-machine and the BET value recorded. The results are shown in Table 3.

[0064] 3) Particle size The particle size distribution was measured according to the national standard GB / T19077-2016 laser diffraction method, and the results are shown in Table 3. Testing instrument: Malvern, Master Size 2000 laser particle size analyzer. Test procedure: 1g of powder was weighed and added to 60ml of pure water, and then externally ultrasonicated for 5 minutes. The sample was then injected into the sample injector, the test was performed, and the test data was recorded. Test conditions: The test principle was Mie theory (light scattering), the detection angle was 0-135°, the external ultrasonic intensity was 40KHz, 180W, the particle refractive index was 1.692, the particle absorption coefficient was 1, the sample test time was 6 seconds, the background test snap count was 6,000 times, and the light blocking rate was 8-12%.

[0065] 4) pH value The measurement was performed using a PHSJ-3F lightning-magnetic pH meter. The specific method was as follows: 5g ± 0.05g of sample was accurately weighed and placed in a beaker. Deionized water was added at a material / water ratio of 1:9 by mass to form a 10% suspension. The magnetic material was placed in the beaker, which was then placed on the magnetic stirrer tray. The magnetic stirrer was rotated at 880 r / min and stirred for 5 minutes. The mixed solution was filtered using qualitative filter paper and a funnel, and then placed in a thermostatic water bath set at 25°C and thermostatically filtered for 20 ± 5 minutes. The electrode was then rinsed with the sample solution. After rinsing, the electrode and temperature sensor were inserted into the sample solution. The pH value was recorded when the reading stabilized and the temperature reached 25°C. The results are shown in Table 3.

[0066] 5) XRD test XRD testing of the sodium ion cathode materials in the examples of the present invention employed an X'Pert PRO MPD analyzer. Test principle: The Bragg equation reflects the relationship between the direction of diffraction rays and crystal structure. For diffraction to occur, the Bragg equation must be satisfied: 2dsinθ=nλ (d: crystal plane spacing, θ: Bragg angle, λ: X-ray wavelength, n: reflection series). When X-rays are irradiated onto a sample, the scattered X-rays from each atom in the crystal interfere with each other, generating strong X-ray diffraction rays in a specific direction. When X-rays are irradiated onto a sample from different angles, diffraction occurs at different crystal planes, and the detector receives the number of diffracted photons reflected from the crystal planes, thereby obtaining a spectrum showing the relationship between angle and intensity. Test conditions: light pipe is Cu target material, wavelength is 1.54060, Be window, incident light path: Soller slit 0.04 rad, divergence slit 1 / 2°, light shielding plate 10 mm, anti-scattering slit 1°, diffraction light path: anti-scattering slit 8.0 mm, Soller slit 0.04 rad, large Ni filter, scanning range 10~90°, scanning step 0.013°, dwell time for each step 30.6 s, voltage 40 kV, current 40 mA. Powder sample preparation: Use a clean sampling spoon to place the powder into the groove of a glass slide (for large particle samples, the powder needs to be polished to <50 μm). Place one side of the blade (>20 mm) on the surface of the glass slide and slightly lift the other side (included angle <10°). Use the edge of the blade to scrape the surface of the powder sample flat, rotate the glass slide 90°, and scrape it flat again. Repeat this process in both directions several times until there is no texture on the surface of the sample. Remove excess powder around the glass slide and place it in the powder diffraction analyzer. Sample analysis: The sample file was opened using the High-Score Plus analysis software. The background was determined, peak detection was selected, peak confirmation was performed, and then iterative fitting was performed. The Williamson-Hall plot was recorded to calculate the grain size. The corresponding phase was selected, phase matching and unit cell refinement were performed, and the half-width of the (110) diffraction peak at a diffraction angle 2θ of approximately 64.9° was recorded. The results are shown in Table 3.

[0067] 6) Moisture The measurement was performed in accordance with the GB / T 11133-2015 Karl Fischer coulometric titration method. 899 Coulometer + 885 Compact Oven SC coulometer was used to test. 0.5-0.8g of sample was weighed using a water bottle. The accuracy was within 0.0001g. The gas flow rate was 50-60ml / min, the heating temperature was 170℃, the initial drift was ≦10μg / min, the final drift was 20μg / min, and the extraction time was 400s. The test results were accurate to one decimal place. The results are shown in Table 3.

[0068] 7) Green density [1] The circular mold was placed on the stage of an electronic pressure tester, and the pressure was slowly increased manually to 1000 kg, after which the displacement and deformation were zero. [2] Weigh out the powder (5.0000±0.1000) and place it in a circular mold. Shake gently to flatten it. Then, place the upper pad of the mold on the sample. Be careful that both pads face the sample with the non-cut surface to prevent the sample from spilling. [3] After filling the sample, the mold was placed on the stage of the electronic pressure tester, and a program was edited to increase the pressure to 8000 kg at a rate of 5 mm / min, hold the voltage constant for 30 s, and then reduce the pressure to zero. [4] When the sample was pressurized to 8000±10 kg (approximately 15-25 s after the pressure reached 8000 kg), the pressure on the sample was recorded and the sample height was read, with an accuracy of 0.001 cm. [5] After the reading was completed, the stage of the electronic pressure tester was manually lowered and the sample was removed using the remover. [6] After removing the sample, the inside of the sample mold was cleaned with alcohol-soaked clean paper to ensure that the inside of the mold was clean, and the experiment was completed. [7] Calculations were made using the formula below, and the results are shown in Table 3.

number

[0069] FIG. 1 is an SEM image of the single crystal sodium ion battery cathode material of Example 1, and it can be seen from FIG. 1 that the material is a single crystal particle and a polygonal layered sheet.

[0070] The single-crystal sodium-ion battery cathode material of Example 1 was thoroughly mixed with the binder polyvinylidene fluoride (PVDF) and conductive carbon black (SP) in a weight ratio of 90:5:5, and stirred to form a uniform slurry. This was then applied to an aluminum foil current collector, dried, and cold-pressed to form a tab. The tab was subjected to SEM examination, as shown in Figure 7, which revealed that the material was still single-crystal particles and that no cracks had occurred on the surface of the material particles.

[0071] Example 2 Sodium carbonate, manganese carbonate, nickel carbonate, iron trioxide, copper oxide, and zinc oxide were weighed out to a total weight of 1.49 kg with an elemental molar ratio of Na:Mn:Ni:Fe:Cu:Zn = 0.81:0.31:0.25:0.28:0.12:0.04. The materials were mixed in an ultra-high-speed multi-function mixer at 3500 r / min for 15 minutes. The homogeneously mixed materials were placed in a muffle furnace and heated to 890°C in an air atmosphere for 16 hours. The mixture was then naturally cooled and crushed in an airflow crusher at a crushing pressure of 0.59 MPa to obtain single-crystalline sodium-ion battery cathode material C2.

[0072] According to the component analysis method in Example 1, the single-crystal sodium ion battery positive electrode material C2 has the chemical formula Na 0.81 Ni 0.25 Mn 0.31 Fe 0.28 Cu 0.12 Zn 0.04 It was measured to be O2.

[0073] The above positive electrode material was tested using the method in Example 1, and the test results are shown in Table 3.

[0074] FIG. 2 is an SEM image of the single crystal sodium ion battery cathode material of Example 2, which shows that the material is a single crystal particle and a polygonal layered sheet.

[0075] The single-crystal sodium-ion battery cathode material of Example 2 was thoroughly mixed with the binder polyvinylidene fluoride (PVDF) and conductive carbon black (SP) in a weight ratio of 90:5:5, and stirred to form a uniform slurry. This was then applied to an aluminum foil current collector, dried, and cold-pressed to form a tab. The tab was subjected to SEM examination, as shown in Figure 8, which revealed that the material was still single-crystal particles and that no cracks had occurred on the surface of the material particles.

[0076] Example 3 Sodium carbonate, manganese trioxide, nickel oxalate, ferrous oxalate, zinc oxide, and aluminum oxide were weighed out to a total weight of 1.75 kg with an elemental molar ratio of Na:Mn:Ni:Fe:Zn:Al = 0.81:0.32:0.20:0.33:0.145:0.005. The materials were mixed in an ultra-high-speed multi-function mixer at 4000 r / min for 15 minutes. The homogeneous mixture was placed in a muffle furnace and heated to 960°C for 10 hours in an air atmosphere. The mixture was then allowed to cool and then crushed in an airflow crusher at a crushing pressure of 0.62 MPa to obtain single-crystalline sodium-ion battery cathode material C3.

[0077] According to the component analysis method in Example 1, the single-crystal sodium ion battery positive electrode material C3 has the chemical formula Na 0.81 Ni 0.2 Mn 0.32 Fe 0.33 Zn 0.145 Al 0.005 It was measured to be O2.

[0078] The above positive electrode material was tested using the method in Example 1, and the test results are shown in Table 3.

[0079] FIG. 3 is an SEM image of the single crystal sodium ion battery cathode material of Example 3, which shows that the material is a single crystal particle and a polygonal layered sheet.

[0080] The single-crystal sodium-ion battery cathode material of Example 3 was thoroughly mixed with the binder polyvinylidene fluoride (PVDF) and conductive carbon black (SP) in a weight ratio of 90:5:5, and stirred to form a uniform slurry. This was then applied to an aluminum foil current collector, dried, and pressed to form a tab. The tab was subjected to SEM examination, as shown in Figure 9. Figure 9 shows that the material is still single-crystal particles, and no cracks have occurred on the surface of the material particles.

[0081] Example 4 Sodium carbonate, manganese carbonate, nickel carbonate, iron trioxide, titanium oxide, and yttrium oxide were weighed out to a total weight of 2.21 kg with an element molar ratio of Na:Mn:Ni:Fe:Ti:Y = 0.77:0.22:0.47:0.09:0.215:0.005. The materials were mixed in an ultra-high-speed multi-function mixer at 2800 r / min for 40 minutes. The homogeneously mixed materials were placed in a muffle furnace and heated to 940°C in an air atmosphere for 11 hours. The mixture was then naturally cooled and crushed in an airflow crusher at a crushing pressure of 0.65 MPa to obtain single-crystal sodium-ion battery cathode material C4.

[0082] According to the component analysis method in Example 1, the single-crystal sodium ion battery positive electrode material C4 has the chemical formula Na 0.77 Ni 0.47 Mn 0.22 Fe 0.09 Ti 0.215 Y 0.005 It was measured to be O2.

[0083] The above positive electrode material was tested using the method in Example 1, and the test results are shown in Table 3.

[0084] FIG. 4 is an SEM image of the single crystal sodium ion battery cathode material of Example 4, which shows that the material is a single crystal particle and a polygonal layered sheet.

[0085] The single-crystal sodium-ion battery cathode material of Example 4 was thoroughly mixed with the binder polyvinylidene fluoride (PVDF) and conductive carbon black (SP) in a weight ratio of 90:5:5, and stirred to form a uniform slurry. This was then applied to an aluminum foil current collector, dried, and pressed to form a tab. The tab was subjected to SEM examination, as shown in Figure 10. Figure 10 shows that the material is still single-crystal particles, and no cracks have occurred on the surface of the material particles.

[0086] Example 5 To obtain a total weight of 1.46 kg with an element molar ratio of Na:Mn:Cu:Fe:Zr = 0.85:0.43:0.2285:0.34:0.0015, the corresponding weights of sodium carbonate, manganese carbonate, copper oxide, ferric oxide, and zirconium oxide were weighed and mixed in an ultra-high-speed multi-function mixer at 2500 r / min for 50 minutes. The homogeneously mixed material was placed in a muffle furnace and heated to 890°C in an air atmosphere for 14 hours. After natural cooling, it was pulverized in an airflow mill at a pulverization pressure of 0.69 MPa to obtain single-crystalline sodium-ion battery cathode material C5.

[0087] According to the component analysis method in Example 1, the single-crystal sodium ion battery positive electrode material C5 has the chemical formula Na 0.85 Mn 0.43 Cu 0.2285 Fe 0.34 Zr 0.0015 It was measured to be O2.

[0088] The above positive electrode material was tested using the method in Example 1, and the test results are shown in Table 3.

[0089] FIG. 5 is an SEM image of the single crystal sodium ion battery positive electrode material of Example 5, and it can be seen from FIG. 5 that the material is single crystal particles and polygonal layered sheets.

[0090] The single-crystal sodium-ion battery cathode material of Example 5 was thoroughly mixed with the binder polyvinylidene fluoride (PVDF) and conductive carbon black (SP) in a weight ratio of 90:5:5, and stirred to form a uniform slurry. This was then applied to an aluminum foil current collector, dried, and pressed to form a tab. The tab was subjected to SEM examination, as shown in Figure 11. Figure 11 shows that the material is still single-crystal particles, and no cracks have occurred on the surface of the material particles.

[0091] Example 6 Sodium carbonate, manganese carbonate, nickel carbonate, ferrous oxalate, zinc oxide, and calcium oxide were weighed out to a total weight of 1.76 kg with an elemental molar ratio of Na:Mn:Ni:Fe:Zn:Ca = 0.86:0.38:0.20:0.32:0.08:0.02. The materials were mixed in an ultra-high-speed multi-function mixer at 3600 r / min for 35 minutes. The homogeneously mixed materials were placed in a muffle furnace and heated to 935°C in an air atmosphere for 20 hours. The mixture was then naturally cooled and crushed in an airflow crusher at a crushing pressure of 0.66 MPa to obtain single-crystalline sodium-ion battery cathode material C6.

[0092] According to the component analysis method in Example 1, the single-crystal sodium ion battery positive electrode material C6 has the chemical formula Na 0.86 Ni 0.29 Mn 0.38 Fe 0.32 Zn 0.08 Ca 0.02 It was measured to be O2.

[0093] The above positive electrode material was tested using the method in Example 1, and the test results are shown in Table 3.

[0094] FIG. 6 is an SEM image of the single crystal sodium ion battery cathode material of Example 6, and it can be seen from FIG. 6 that the material is single crystal particles and polygonal layered sheets.

[0095] The single-crystal sodium-ion battery cathode material of Example 6 was thoroughly mixed with the binder polyvinylidene fluoride (PVDF) and conductive carbon black (SP) in a weight ratio of 90:5:5, and stirred to form a uniform slurry. This was then applied to an aluminum foil current collector, dried, and pressed to form a tab. The tab was subjected to SEM examination, as shown in Figure 12. Figure 12 shows that the material is still single-crystal particles, and no cracks have occurred on the surface of the material particles.

[0096] (Comparative Example 1) Sodium carbonate and nickel manganese iron precursor (Ni) were added in a molar ratio of 0.83:1 with a total weight of 1.40 kg. 0.27 Mn0.38 Fe 0.35 Each of the materials was weighed and mixed in an ultra-high speed multi-function mixer at a rotation speed of 3600 r / min for 35 minutes. The homogeneously mixed material was placed in a muffle furnace and heated at 890°C for 16 hours in an air atmosphere. Then, it was naturally cooled, ball milled, and sieved to obtain the finished product D1.

[0097] According to the component analysis method in Example 1, the sodium ion battery positive electrode material D1 has the chemical formula Na 0.83 Ni 0.27 Mn 0.38 Fe 0.35 It was measured to be O2.

[0098] The above positive electrode material was tested using the method in Example 1, and the test results are shown in Table 3.

[0099] The positive electrode material for a sodium ion battery of Comparative Example 1 was subjected to an SEM test, and as shown in FIG. 13, it can be seen from FIG. 13 that the material is a secondary particle aggregate formed by aggregating a plurality of primary particles.

[0100] The positive electrode material for sodium ion batteries of Comparative Example 1, the binder polyvinylidene fluoride (PVDF), and conductive carbon black (SP) were thoroughly mixed in a weight ratio of 90:5:5, and stirred to form a uniform slurry, which was then applied to an aluminum foil current collector, dried, and pressed to form a tab, and the tab was subjected to SEM examination, as shown in Figure 14 Figure 14 shows that most of the secondary particle aggregates of the material have been crushed, exposing a fresh interface.

[0101] [Table 3]

[0102] As can be seen from Table 3, in the powder X-ray diffraction spectra (XRD) of the single crystal sodium ion battery positive electrode materials produced in Examples 1 to 6, the full width at half maximum (FWHM) (110) of the (110) diffraction peak at a diffraction angle 2θ of approximately 64.9° was 0.152 to 0.274, the water mass content was 2400 ppm or less, the pH was less than 13.1 in all cases, and the specific surface area was 0.45 to 0.93 m 2 / g, and particle size D V 50 is 4.1 to 12.6 μm and the green density is 2.95 to 3.92 g / cm 3 When a sodium ion cathode material was prepared using the chemical composition of Comparative Example 1, the water mass content was 4320 ppm, which was much larger than 3000 ppm, the pH was 13.46, which was larger than 13.1, and the specific surface area was also much smaller than that of the examples of the present invention.

[0103] (Experimental Example 1) Fabrication and performance evaluation of sodium-ion batteries.

[0104] CR2430 button cell batteries are manufactured according to the following method. Positive electrode preparation: The positive electrode materials for sodium ion batteries prepared in Examples 1 to 6 of the present invention and Comparative Example 1, respectively, were thoroughly mixed with polyvinylidene fluoride (PVDF) as a binder and conductive carbon black (SP) in a weight ratio of 7:2:1, stirred to form a uniform slurry, which was then applied to an aluminum foil current collector, dried, and pressed to form tabs, which were designated as PE-C1, PE-C2, PE-C3, PE-C4, PE-C5, PE-C6, and PE-D1, respectively. The pressed positive electrode tab was punched out, weighed, and sintered. The battery was then assembled in a vacuum glove box. First, the bottom of the button battery case was placed on top of it, followed by a 2.5mm nickel foam sheet and a negative electrode metallic sodium sheet (manufacturer: Shenzhen Youken Technology Co., Ltd.). 0.5g of electrolyte was then poured into the battery under a relative humidity of less than 1.5%. The electrolyte was a 1 mol / L sodium hexafluorophosphate solution, made from a 1:1:1 mixed solvent of ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC). A separator and a positive electrode tab were then placed on the battery case, and the battery case was then sealed to obtain button batteries with model number CR2430. These batteries are designated BA-C1, BA-C2, BA-C3, BA-C4, BA-C5, BA-C6, and BA-D1, respectively.

[0105] The battery was subjected to a performance test on a battery test system according to the following method, and the results are shown in Table 4. 1) Capacity test The manufactured button cell battery was mounted on a test stand and the test program was started. The test temperature was set to 25°C, the battery was left standing for 4 hours, the battery was charged at a constant current of 0.1C to 4.0V, the battery was paused, the battery was left standing for 5 minutes, and the battery was discharged at a constant current of 0.1C to 2.0V, and the capacity at the current and voltage was obtained. 2) Cycle test The battery that has undergone the above capacity test is mounted on a test stand, and the test program is started. The set steps are: test temperature is set to 45°C, left to stand for 4 hours, constant current charging at 0.1C to 4.0V, constant voltage charging at 4.0V for 2 hours, left to stand for 5 minutes, and then constant current discharging at 0.1C to a cutoff voltage of 2.0V, left to stand for 5 minutes. The previous constant current charging start step is repeated to perform a cycle test, and the capacity retention rate according to the number of cycles can be obtained.

[0106] [Table 4]

[0107] As can be seen from Table 4, the sodium ion batteries manufactured using the positive electrode materials for single crystalline sodium ion batteries manufactured in Examples 1 to 6 had capacities of 133.0 to 140 mAh / g at a current of 0.1 C and a voltage of 4.2 V (cut-off voltage of 2.0 V), and had capacity retention rates of 90.05 to 94.24% after 50 cycles under conditions of 4.0 V to 2.0 V and 0.1 C / 0.1 C. The sodium ion battery manufactured using the positive electrode material for single crystalline sodium ion batteries manufactured in Comparative Example 1 had a capacity retention rate of only 77.64% after 50 cycles under conditions of 4.0 V to 2.0 V and 0.1 C / 0.1 C. FIG. 15 also shows that the capacity retention rates during cycle testing of the sodium ion batteries manufactured using the positive electrode materials for single crystalline sodium ion batteries manufactured in Examples 1 to 6 were clearly superior to those of Comparative Example 1.

[0108] After 50 cycles of battery BA-C1, the battery was disassembled and the positive electrode tab was taken out for SEM examination, as shown in Fig. 16. From Fig. 16, it can be seen that the single crystal particles remain intact even after cycling without any particle cracks.

[0109] The above description is merely a preferred embodiment of the present invention and does not limit the present invention in any way. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention must be included in the protection scope of the present invention.

[0110] (Addendum) (Appendix 1) A single-crystal sodium-ion battery positive electrode material, comprising: The chemical formula of the positive electrode material for single crystal sodium ion batteries is Na 1+a Ni 1-x-y-z Mn x Fe y M z O2, where -0.40≦a≦0.25, 0.08≦x≦0.5, 0.05≦y≦0.5, 0≦z<0.26; The M is one or more elements selected from Ti, Zn, Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, and Cu elements; A positive electrode material for a single crystal sodium ion battery.

[0111] (Appendix 2) -0.33≦a≦0, 0.10≦x≦0.5, 0.15≦y≦0.5, 2. The positive electrode material for a single crystal sodium ion battery according to claim 1,

[0112] (Appendix 3) The M is one or more selected from Zn, Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, and Cu; 2. The positive electrode material for a single crystal sodium ion battery according to claim 1,

[0113] (Appendix 4) The M is one or more of Zn, Al, B, Ti, Ca, Y, Mg, Nb, Zr, and Cu; 2. The positive electrode material for a single crystal sodium ion battery according to claim 1,

[0114] (Appendix 5) -0.40≦a≦0.25, 0.08≦x≦0.5, 0.05≦y≦0.5, 0≦z≦0.16; 2. The positive electrode material for a single crystal sodium ion battery according to claim 1,

[0115] (Appendix 6) The positive electrode material for a sodium ion battery has a microscopic topography that is a single crystal topography under a scanning electron microscope, and the shape of the single crystal topography particles is one or more of a sphere, a pseudo-sphere, a polygon, or a layered sheet. 2. The positive electrode material for a single crystal sodium ion battery according to claim 1,

[0116] (Appendix 7) In the powder X-ray diffraction spectrum (XRD) of the single crystal sodium ion battery positive electrode material, the full width at half maximum (FWHM) (110) of the (110) diffraction peak at a diffraction angle 2θ of about 64.9° is 0.06 to 0.35. 2. The positive electrode material for a single crystal sodium ion battery according to claim 1,

[0117] (Appendix 8) The green density of the positive electrode material for single crystal sodium ion batteries under a pressure of 7000 to 9000 kg is 2.8 to 4.2 g / cm 3 That is, 8. The positive electrode material for a single crystal sodium ion battery according to any one of appendices 1 to 7,

[0118] (Appendix 9) The water mass content of the monocrystalline sodium-ion battery positive electrode material is less than 3000 ppm; 8. The positive electrode material for a single crystal sodium ion battery according to any one of appendices 1 to 7,

[0119] (Appendix 10) The pH value of the positive electrode material for the monocrystalline sodium ion battery is within 13.1. 8. The positive electrode material for a single crystal sodium ion battery according to any one of appendices 1 to 7,

[0120] (Appendix 11) The specific surface area of ​​the positive electrode material for the single crystal sodium ion battery is 0.35 to 1.2 m 2 / g, and the particle size D of the positive electrode material for the single crystal sodium ion battery V 50 is 2.0 to 16.0 μm, 8. The positive electrode material for a single crystal sodium ion battery according to any one of appendices 1 to 7,

[0121] (Appendix 12) mixing raw materials including a sodium source compound, an iron source compound, and a manganese source compound, and optionally adding a nickel source compound and / or an M source compound, sintering, and pulverizing the mixture to obtain a single-crystal sodium-ion battery positive electrode material; 8. A method for producing a positive electrode material for a single crystal sodium ion battery according to any one of appendices 1 to 7.

[0122] (Appendix 13) The sintering temperature is 860 to 990°C. 13. The method of claim 12,

[0123] (Appendix 14) The grinding pressure is 0.1 to 1 MPa. 13. The method of claim 12,

[0124] (Appendix 15) the sodium source compound includes a salt and / or hydroxide containing sodium element; and / or the manganese source compound includes one or more of an oxide, a hydroxide, or a salt containing manganese element; and / or the nickel source compound includes one or more of an oxide, a hydroxide, or a salt containing nickel element; and / or the iron source compound includes one or more of an oxide, a hydroxide, or a salt containing an iron element; and / or the M source compound includes an oxide and / or a salt containing the M element; 13. The method of claim 12,

[0125] (Appendix 16) Produced by the production method described in Appendix 12. A positive electrode material for a single crystal sodium ion battery.

[0126] (Appendix 17) The active material is a positive electrode material for a single-crystal sodium-ion battery according to any one of Supplementary Notes 1 to 7 or Supplementary Note 16. Positive electrode for sodium-ion batteries.

[0127] (Appendix 18) Supplementary Note 17: A sodium-ion battery characterized by:

Claims

[Claim 1] A single-crystal sodium-ion battery positive electrode material, comprising: The chemical composition formula of the positive electrode material for a single crystal sodium ion battery is Na except when the value of 1-x-y-z is 0 or negative. １＋ａ Ni １－ｘ－ｙ－ｚ Mn ｘ Fe ｙ M ｚ O ２ where −0.40≦a≦0.25, 0.08≦x≦0.5, 0.05≦y≦0.5, and 0<z<0.26; M is one or more selected from Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, and Cu elements; The green density of the positive electrode material for the single crystal sodium ion battery under a pressure of 7000 to 9000 kg is 3.14 cm ２ 2.8 to 4.2 g / cm ３ That is, A positive electrode material for a single crystal sodium ion battery.

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