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

Abstract

To provide a mono-crystalline cathode material for a sodium-ion battery, capable of improving cycle performance of the sodium-ion battery.SOLUTION: A mono-crystalline cathode material for a sodium ion battery contains elements of composition represented by a chemical formula of Na1+aNi1-x-y-z-cMnxFeyMzNcO2 where -0.40≤a≤0.25, 0.08≤x≤0.5, 0.05≤y≤0.5, 0≤z<0.26, and 0<c<0.1 are satisfied, and the M and N are both one or a combination of two or more selected from a group consisting of 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 elements.EFFECT: The mono-crystalline cathode material for a sodium-ion battery has a specific chemical composition, a mono crystal topography and good structural stability and integrity. Particle fragmentation cannot be produced in a cyclic process, and meanwhile, cyclic stability of the sodium-ion battery can be improved.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium-ion batteries, and specifically relates to a cathode material for a single-crystal sodium-ion battery, a method for manufacturing the same, and an application thereof.

Background Art

[0002] With the intensification of competition in lithium-ion batteries, in addition to supply-demand relationships and resource regulations, the price of lithium salts has soared, and sodium-ion batteries with cost advantages have gradually become the focus of research by major companies and universities. Sodium-ion batteries operate on the same principle as lithium-ion batteries. However, in comparison, since the ionic radius of sodium ions is larger and the diffusion rate is slower, 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 mainly form products in systems such as transition metal oxides, Prussian blue, and polyanion phosphates. Among them, transition metal oxides have relatively high specific capacities and thus gain popularity. However, poor cycle performance and low energy density are important factors affecting the application of cathode materials for sodium-ion batteries.

[0004] The transition metal oxides currently on the market are mainly divided into two types: nickel manganese iron copper-based oxides containing copper elements and nickel iron manganese-based oxides. In either type, by changing the different compounding ratios of nickel, iron, manganese, and copper elements, cathode materials for sodium-ion batteries with different performances can be obtained. Also, due to the different compounding ratios of the elements, the stability of the material when in contact with the electrolyte also changes. On the other hand, the factors affecting the cycle life of the cathode material for sodium-ion batteries are: 1. the reconstruction of the surface crystal structure during cycling; 2. the destruction of aggregated particles due to anisotropic volume expansion during cycling. According to research, the connection structure between particles inside the aggregated particles leads to an increase in the local current density, thereby generating a very large stress, which is found to affect the cycle characteristics of the material. Also, there is a phenomenon of inconsistent charging states between different parts inside the particles, which affects the electrochemical performance of the electrode.

[0005] Also, when the amount of sodium deintercalation of the cathode material for sodium-ion batteries is relatively large, the structure becomes very fragile, the active metal and oxygen in the lattice are displaced, reaching a certain high temperature and high pressure, and the atomic rearrangement and reconstruction gradually intensify, resulting in a large change in the volume and substance phase of the crystal grains. On the other hand, when the cathode material is deintercalated with sodium, the oxidizing power becomes stronger, and chemical and electrochemical reactions with the electrolyte are extremely likely to occur. The material is prone to deoxidation, the transition metal dissolves, especially the electrolyte is oxidized under high voltage, and H + is generated, the acidity of the electrolyte is improved, thereby the surface film of the electrode material is damaged by HF, the components and structure of the interface further change, and it has a serious impact on the electrochemical performance and cycle performance of the material.

Summary of the Invention

Problems to be Solved by the Invention

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

[0007] In view of the above technical problems, as a result of intensive research by the inventors of the present application, a cathode material for a single-crystal sodium-ion battery having a single-crystal topography is obtained. By adopting surface coating or simultaneously performing bulk-phase doping and surface coating modification, direct contact between the material and the electrolyte, especially HF in the electrolyte, can be effectively avoided, thereby preventing the occurrence of side reactions, suppressing the crystal phase transition of the material, improving the cycle stability of the material, and applying it to a sodium-ion battery, especially a power-type sodium-ion battery, can effectively improve the high-temperature and high-voltage cycle performance of the battery, especially the high-temperature stability.

Means for Solving the Problems

[0008] The technical solution of the present invention is as follows. The present invention provides a cathode material for a single-crystal sodium-ion battery, and the cathode material for a single-crystal sodium-ion battery contains elements having a composition represented by Chemical Formula 1. The Chemical Formula 1 is Na 1+a Ni 1-x-y-z-c Mn x Fe y M z N c O2, where -0.40 ≦ a ≦ 0.25, 0.08 ≦ x ≦ 0.5, 0.05 ≦ y ≦ 0.5, 0 ≦ z < 0.26, 0 < c < 0.1. M is a doping element, and N is a coating element. Both M and N are selected from one or more of the elements 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.

[0009] Preferably, in the above cathode material for a single-crystal sodium-ion battery, -0.40 ≦ a ≦ 0, 0.15 ≦ x ≦ 0.5, and 0.15 ≦ y ≦ 0.5.

[0010] Preferably, in the above-described single-crystal sodium-ion battery positive electrode material, 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, or Cu, preferably one or more of Zn, Al, B, Ti, Ca, Y, Mg, Nb, Zr, or Cu, more preferably Zn, and preferably, 0 ≦ z ≦ 0.13.

[0011] Preferably, in the above-described single-crystal sodium-ion battery positive electrode material, N is one or more selected from Al, Ti, Co, Mn, Y, B, F, P, Nb, Zr, W, Sr, or Mg, preferably one or more of Al, Ti, B, Nb, or Mg, and preferably, 0 < c < 0.05.

[0012] Preferably, for the positive electrode material for the single-crystal sodium-ion battery, under a scanning electron microscope, its microscopic topography is a single-crystal topography, and preferably, the shape of the single-crystal topography particles is one or more of spherical, pseudo-spherical, polygonal, or layered sheet.

[0013] Preferably, in the powder X-ray diffraction spectrum (XRD) of the positive electrode material for the single-crystal sodium-ion battery, the full width at half maximum FWHM(110) of the (110) diffraction peak where the diffraction angle 2θ is around 64.9° is 0.08 - 0.35.

[0014] Preferably, the tap density of the positive electrode material for the single-crystal sodium-ion battery under a pressure of 7000 - 9000 kg is 2.8 - 4.2 g / cm 3 is.

[0015] Preferably, the moisture mass content of the positive electrode material for the single-crystal sodium-ion battery is less than 1500 ppm, preferably less than 1000 ppm, and more preferably less than 900 ppm.

[0016] Preferably, the pH value of the positive electrode material for the single-crystal sodium ion battery is within 12.6.

[0017] Preferably, the specific surface area of the positive electrode material for the single-crystal sodium ion battery is 0.35 - 1.2 m 2 / g.

[0018] Preferably, the particle size D V 50 of the positive electrode material for the single-crystal sodium ion battery is 2.00 - 16.0 μm, preferably 2.50 - 12.0 μm.

[0019] The present invention further provides a method for manufacturing the above positive electrode material for a single-crystal sodium ion battery, mixing raw materials including a sodium source compound, a manganese source compound, and an iron source compound, and adding a nickel source compound and an M source compound as necessary, and performing the first sintering, followed by pulverization to obtain a semi-finished product in step (1); step (2) of mixing the semi-finished product obtained in step (1) and raw materials of an N source compound, followed by performing the second sintering, and pulverizing to obtain a positive electrode material for a single-crystal sodium ion battery.

[0020] Preferably, in the above manufacturing method, the temperature of the first sintering in step (1) is 860 - 990 °C, preferably 880 - 980 °C, and preferably, the constant temperature time is 6 - 40 hours.

[0021] Preferably, in the above manufacturing method, the temperature of the second sintering in step (2) is 350 - 900 °C, preferably 350 - 800 °C, and preferably, the constant temperature time is 2 - 15 hours.

[0022] Preferably, in the above manufacturing method, the pulverization pressure in both step (1) and step (2) is 0.1 - 1 MPa.

[0023] Preferably, in the above manufacturing method, the sodium source compound contains a salt and / or a hydroxide containing sodium element. 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.

[0024] Preferably, in the above manufacturing method, the manganese source compound contains one or more of an oxide, a hydroxide, or a salt containing manganese element. Preferably, the manganese source compound is one or more selected from the group consisting of manganese dioxide, manganese trioxide, manganese oxide, manganese carbonate, manganese oxalate, manganese sulfate, manganese acetate, manganese chloride, and manganese nitrate.

[0025] Preferably, in the above manufacturing method, the nickel source compound contains one or more of an oxide, a hydroxide, or a salt containing nickel element. 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.

[0026] Preferably, in the above manufacturing method, the iron source compound contains one or more of an oxide, a hydroxide, or a salt containing iron element. Preferably, the iron source compound is one or more selected from the group consisting of ferric oxide, ferrous oxalate, ferrous sulfate, ferrous acetate, and ferrous nitrate.

[0027] Preferably, the M source compound contains an oxide and / or salts containing M element. Preferably, the M source compound contains one or more of calcium oxide, calcium hydroxide, boron trioxide, boric acid, niobium oxide, aluminum oxide, titanium oxide, magnesium oxide, copper oxide, yttrium trioxide, zirconium oxide, sodium fluoride, lithium fluoride, copper oxide, zinc oxide, and copper sulfate.

[0028] Preferably, the N-source compound contains an oxide and / or salts containing N element. Preferably, the N-source compound contains one or more of calcium oxide, boron trioxide, boric acid, niobium oxide, aluminum oxide, aluminum acetate, aluminum nitrate, titanium oxide, magnesium oxide, magnesium acetate, magnesium nitrate, copper oxide, yttrium trioxide, zirconium oxide, zirconium acetate, sodium fluoride, lithium fluoride, titanium white powder, titanium oxide dispersion, zinc oxide, and copper sulfate.

[0029] The present invention further provides a cathode material for a single crystal sodium ion battery produced by the above manufacturing method.

[0030] The present invention further provides a cathode for a sodium ion battery, wherein the active material is the above cathode material for a single crystal sodium ion battery.

[0031] The present invention further provides a sodium ion battery including the above cathode for a sodium ion battery.

[0032] The present invention further provides an application of the above cathode material for a single crystal sodium ion battery, the above cathode for a sodium ion battery, or the above sodium ion battery in solar power generation, wind power generation, smart grid, distributed power plant, household energy storage battery, low-end two-wheeler battery, or low energy density power battery.

Advantages of the Invention

[0033] The beneficial effects of the present invention are as follows. (1) Since the positive electrode material for a single-crystal sodium-ion battery of the present invention has a specific chemical composition and single-crystal topography, the positive electrode material for a sodium-ion battery has good structural stability and does not cause significant structural changes due to frequent desorption of sodium ions during charge and discharge of the sodium-ion battery. Further, the material has a complete structure, good processing performance, the particles do not crack during cycling, effectively prevents direct contact between the material surface and the electrolyte, particularly contact with HF in the electrolyte, prevents the occurrence of side reactions, and improves the cycle stability of the sodium-ion battery. (2) By coating treatment, the positive electrode material for a single-crystal sodium-ion battery of the present invention has a low pH value, a low residual alkali amount, and a low moisture content, so that the positive electrode material for a single-crystal sodium-ion battery does not gel due to water absorption during the pulping process of the battery, improves the stability of the sodium-ion battery electrode slurry, and thereby further improves the cycle stability of the sodium-ion battery.

Brief Description of the Drawings

[0034]

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Embodiments for Carrying Out the Invention

[0035] To make the objects, technical solutions and technical effects of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The embodiments described below are some embodiments of the present invention, not all embodiments. Together with the embodiments of the present invention, all other embodiments obtained on the premise that those skilled in the art do not perform creative labor belong to the protection scope of the present invention.

[0036] D of the present invention V 50 is the particle size corresponding to when the percentage of the volume cumulative particle size distribution number in the sample reaches 50%.

[0037] In order to improve the cycle performance of the sodium-ion battery, the present invention manufactures the positive electrode material for the sodium-ion battery as single crystal particles, improves the structural stability of the material, effectively suppresses the change of the structure, strengthens the reversibility of the material, and at the same time performs surface coating on the positive electrode material for the sodium-ion battery, or simultaneously performs bulk phase doping and surface coating modification, thereby effectively avoiding the direct contact between the material and the electrolyte, especially HF in the electrolyte, thereby preventing the occurrence of side reactions, suppressing the crystal phase transition of the material, and thereby improving the cycle stability of the material.

[0038] In one specific embodiment of the present invention, the present invention provides a positive electrode material for a single crystal sodium-ion battery, and the material contains elements with a composition represented by Chemical Formula 1. The Chemical Formula 1 is Na 1+a Ni 1-x-y-z-c Mn x Fe y M z N cO2, where -0.40 ≦ a ≦ 0.25, 0.08 ≦ x ≦ 0.5, 0.05 ≦ y ≦ 0.5, 0.0 ≦ z < 0.26, 0 < c < 0.1, M is a doping element, and N is a coating element. The M and N are one or more selected from the group consisting of 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.

[0039] In a preferred embodiment of the present invention, in the above chemical formula 1, -0.40 ≦ a ≦ 0, 0.15 ≦ x ≦ 0.5, and 0.15 ≦ y ≦ 0.5.

[0040] In a preferred embodiment of the present invention, the above M is one or more selected from the group consisting of 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, preferably one or more of Zn, Al, B, Ti, Ca, Y, or Cu, more preferably Zn, and preferably 0 ≦ z ≦ 0.13.

[0041] In still another preferred embodiment of the present invention, the N is one or more selected from the group consisting of Al, Ti, Co, Mn, Y, B, F, P, Nb, Zr, W, Sr, and Mg, preferably one or more of Al, Ti, B, Nb, or Mg, and preferably 0 < c < 0.05.

[0042] In the present invention, the above positive electrode material for a single crystal 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 spherical, pseudo-spherical, polygonal, or layered sheet.

[0043] In the present invention, in the powder X-ray diffraction spectrum (XRD) of the above-mentioned single-crystal sodium-ion battery cathode material, the full width at half maximum FWHM(110) of the (110) diffraction peak at a diffraction angle 2θ of around 64.9° (in the present invention, around a diffraction angle X° means the diffraction angle is X° ± 1°, for example, around 64.9° means 64.9° ± 1°, that is, 63.9° to 65.9°) is 0.08 to 0.35.

[0044] In the present invention, the tap density of the above-mentioned single-crystal sodium-ion battery cathode material under a pressure of 7000 to 9000 kg is 2.8 to 4.2 g / cm 3 in between.

[0045] In the present invention, the specific surface area of the above-mentioned single-crystal sodium-ion battery cathode material is 0.35 to 1.2 m 2 / g.

[0046] In the present invention, the particle size D V 50 of the above-mentioned single-crystal sodium-ion battery cathode material is 2.00 to 16.0 μm, preferably 2.50 to 12.0 μm.

[0047] Since the single-crystal sodium-ion battery cathode material of the present application has the above specific chemical composition and topography, the specific surface area (BET) of the material is within a reasonable range, the intermolecular force on the material surface is at a relatively balanced position, it is difficult to self-aggregate even in an environment with relatively high humidity, and the moisture level of the material is relatively low.

[0048] In the present invention, the moisture content of the above-mentioned single-crystal sodium-ion battery cathode material is less than 1500 ppm, preferably less than 1000 ppm, and more preferably less than 900 ppm.

[0049] In the present invention, the pH value of the above-mentioned single-crystal sodium-ion battery cathode material is within 12.6.

[0050] Since the cathode material for single-crystal sodium-ion batteries of this application has the above specific chemical composition and topography, a coating treatment is applied to make the cathode material for single-crystal sodium-ion batteries have a low pH value, a low residual alkali amount, and a low water content, so that the cathode material for single-crystal sodium-ion batteries does not gel due to water absorption during the pulping process of the battery, and the stability of the sodium battery electrode slurry is improved.

[0051] The present invention further provides a method for manufacturing the above-mentioned cathode material for single-crystal sodium-ion batteries, which includes at least two sinterings and two grindings.

[0052] In a preferred embodiment of the present invention, the manufacturing method is as follows: Step (1): Mix raw materials including a sodium source compound, a manganese source compound, and an iron source compound, and add raw materials of a nickel source compound and an M source compound as needed, and then perform the first sintering and grinding to obtain a semi-finished product. Step (2): After mixing the semi-finished product obtained in step (1) with a raw material containing an N source compound, perform the second sintering and grinding to obtain a cathode material for single-crystal sodium-ion batteries.

[0053] In the above manufacturing method, the first sintering in step (1) is sintered at a temperature of 860-990°C for 6-40 hours. Preferably, the first sintering temperature is 880-980°C, and the atmosphere used for sintering is air, oxygen, or a mixed gas of air and oxygen. The second sintering in step (2) is sintered at a temperature of 350-900°C for 2-15 hours. Preferably, the second sintering temperature is 350-800°C, and the atmosphere used for sintering is air, oxygen, or a mixed gas of air and oxygen. The grinding pressure in both step (1) and step (2) is 0.1-1 MPa.

[0054] In the above manufacturing method, the sodium source compound is a salt and / or hydroxide containing sodium, and includes, for example, one or more of sodium carbonate, sodium formate, sodium hydroxide, sodium acetate, sodium chloride, and sodium fluoride.

[0055] In the above manufacturing method, the manganese source compound is one or more of an oxide containing manganese, a hydroxide, or a salt containing manganese, and includes, for example, one or more of manganese dioxide, manganese trioxide, manganese oxide, manganese carbonate, manganese oxalate, manganese sulfate, manganese acetate, manganese chloride, and manganese nitrate.

[0056] In the above manufacturing method, the nickel source compound is one or more of an oxide containing nickel, a hydroxide, or a salt containing nickel, and includes, for example, one or more of nickel carbonate, nickel oxalate, nickel sulfate, nickel acetate, nickel chloride, and nickel nitrate.

[0057] In the above manufacturing method, the iron source compound is one or more of an oxide containing iron, a hydroxide, or a salt containing iron, and includes, for example, one or more of ferric oxide, ferrous oxalate, ferrous sulfate, ferrous acetate, and ferrous nitrate.

[0058] In the above manufacturing method, the M source compound includes an oxide and / or salts containing the M element, and includes, for example, one or more of calcium oxide, calcium hydroxide, boron trioxide, boric acid, niobium oxide, aluminum oxide, titanium oxide, magnesium oxide, copper oxide, yttrium trioxide, zirconium oxide, sodium fluoride, lithium fluoride, copper oxide, zinc oxide, and copper sulfate.

[0059] In the above manufacturing method, the N source compound includes oxides and / or salts containing N element, for example, it contains one or more of calcium oxide, boron trioxide, boric acid, niobium oxide, aluminum oxide, aluminum acetate, aluminum nitrate, titanium oxide, magnesium oxide, magnesium acetate, magnesium nitrate, copper oxide, yttrium trioxide, zirconium oxide, zirconium acetate, sodium fluoride, lithium fluoride, titanium white powder, titanium oxide dispersion, zinc oxide, and copper sulfate.

[0060] The present invention further provides a positive electrode for a sodium-ion battery, wherein the active material is the above single-crystal sodium-ion battery positive electrode material.

[0061] The present invention further provides a sodium-ion battery including the above positive electrode for a sodium-ion battery.

[0062] 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 is made of a material including a positive electrode current collector, a positive electrode active material coated on the positive electrode current collector, a binder, a conductive assistant, etc., and the positive electrode active material is the positive electrode material of the present invention. The negative electrode is made of a material including a metallic sodium sheet or a current collector, a negative electrode active material coated on the current collector, a binder, a conductive assistant, etc., the separator is a PP / PE film generally used in the industry, and is used to separate the positive electrode and the negative electrode from each other. The aluminum plastic film is an inclusion of the positive electrode, the negative electrode, the separator, and the electrolyte.

[0063] The binder in the present invention is mainly used to improve the binding properties between the positive electrode active material particles and between the positive electrode active material particles and the current collector. As the binder in the present invention, a commercially available ordinary binder used in the art can be selected. Specifically, the binder may be selected from polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymer, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1,1-difluoroethylene, polyethylene, polypropylene, styrene butadiene rubber, acrylic acid (ester) styrene butadiene rubber, epoxy resin, nylon, or a composition thereof.

[0064] As the conductive assistant in the present invention, a commercially available ordinary conductive assistant used in the art can be selected. Specifically, the conductive assistant may be selected from carbon-based materials (such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, or carbon fiber), metal-based materials (such as metal powder or metal fiber containing copper, nickel, aluminum, silver, etc.), conductive polymers (such as polyphenylene derivatives), or a composition thereof.

[0065] The present invention further provides an application of the above single crystal sodium ion battery positive electrode material, or the above sodium ion electrode, or the above sodium ion battery in solar power generation, wind power generation, smart grid, distributed power plant, household energy storage battery, low-end two-wheeler battery, or low energy density power battery.

[0066] Hereinafter, the beneficial effects of the present invention will be further described by specific examples.

[0067] The raw materials or reagents used in the present invention were all purchased from major market manufacturers. If the manufacturer is not specified or the concentration is not specified, they are all analytical raw materials or reagents that are usually available and are not particularly limited as long as they exhibit the intended effect. The instruments and equipment used in this example were all purchased from major market manufacturers and are not particularly limited as long as they exhibit the intended effect. When specific techniques or conditions are not specified in this example, they are carried out according to the techniques or conditions described in the literature of the technical field or according to the product manuals.

[0068] The raw materials and instruments used in the following examples and comparative examples are as shown in Table 1.

[0069]

Table 1

[0070]

Table 2

[0071] (Example 1) With an element molar ratio of Na:Mn:Ni:Fe:B = 0.87:0.33:0.33:0.33:0.01 and a total weight of 1.59 kg, the corresponding weights of sodium carbonate, manganese carbonate, nickel carbonate, ferric oxide and boron oxide were weighed respectively, and added to an ultra-high-speed multifunctional mixer and mixed at a rotation speed of 4000 r / min for 20 min. The uniformly mixed material was put into a muffle furnace and kept at a constant temperature of 870 °C for 12 h in an air atmosphere, and then naturally cooled, and pulverized using an air flow pulverizer at a pulverization pressure of 0.62 MPa to obtain a semi-finished product. Weighed 1.08 kg of the above-mentioned semi-finished product and 0.0097 kg of aluminum oxide, added them to a ball mill can, ball milled at 40 Hz for 10 min, and then put the uniformly mixed material into a muffle furnace. It was kept at a constant temperature of 800 °C for 4 hours under an air atmosphere and then cooled naturally. It was pulverized using a jet mill at a pulverization pressure of 0.58 MPa, sieved, and the positive electrode material C1 for single-crystal sodium-ion batteries was obtained.

[0072] Characterized and analyzed the above positive electrode material according to the following method. 1) Component analysis The component analysis of the above positive electrode material was carried out using ICP. (1) Sample pretreatment Weighed a sample of 0.2000 - 0.2100 (accuracy from 0.001 g) into a 100 mL quartz beaker, added 10 mL of aqua regia (prepared by mixing 37 wt% concentrated hydrochloric acid and 65 wt% concentrated nitric acid in a volume ratio of 1:1) along the beaker wall, covered it with a watch glass, heated it at 180 °C for 30 min, transferred all the solution to a 50 mL volumetric flask, fixed the volume with deionized water, shook it well, aspirated 1 mL of the solution from the well-shaken 50 mL volumetric flask into a 100 mL volumetric flask, added 5 mL (25%) of nitric acid to the volumetric flask, and fixed the volume with deionized water. (2) Component analysis test was carried out using the calibration curve method. According to the above method, the chemical formula of the positive electrode material C1 for single-crystal sodium-ion batteries was measured to be Na 0.87 Ni 0.32 Mn 0.32 Fe 0.33 B 0.01 Al 0.02 O2.

[0073] 2) Specific surface area Measured according to the national standard GB / T19587 - 2006 Determination method for specific surface area of solids by gas adsorption BET method. Analytical instrument: TristarII3020 fully automatic specific surface area and pore size distribution measuring device. Test parameters: Adsorbate N2, 99.999%, coolant liquid nitrogen, P0 measured, volume measurement mode, adsorption pressure deviation 0.05 mmHg, equilibrium time 5 s, selection of relative pressure points P / P0: 0.05, 0.1, 0.15, 0.2, 0.25, 0.30, Sample pretreatment: Weigh the empty sample tube + plug mass record M1, weigh a sample amount of 3.8 - 4.2 g, add it to a 9.5 mm specific surface area sample tube with a 3 / 8 inch ball valve, set the temperature to 200 °C using a FlowPrep 060 degassing station, purge with an inert gas and heat degas for 0.5 h, take it out and cool to room temperature, then weigh the mass record M2 of the sample tube + plug + sample, and the sample mass M = M2 - M1. Conduct an on-machine test and record the BET value. The results are shown in Table 3.

[0074] 3) Particle size Measured according to the national standard GB / T19077 - 2016 laser diffraction method for particle size distribution, and the results are shown in Table 3. Test instrument: Malvern, Master Size 2000 laser particle size analyzer. Test steps: Weigh 1 g of powder, add it to 60 ml of pure water, perform external ultrasonic treatment for 5 min, inject the sample into the sample injection device, conduct the test, and record the test data. Test conditions: The test principle is the Mie (light scattering) theory, the detection angle is 0 - 135°, the external ultrasonic intensity is 40 KHz, 180 w, the particle refractive index is 1.692, the particle absorption rate is 1, the sample test time is 6 s, the background test snap number is 6,000 times, and the light obscuration rate is 8 - 12%.

[0075] 4) pH value Measurements were taken using a PHSJ-3F pH meter from Leici. The specific method is as follows: accurately weigh 5 g ± 0.05 g of the sample, add deionized water at a mass ratio of the material to water of 1:9, prepare a 10% suspension, add a magnetic substance, place it on the tray of a magnetic stirrer, set the rotation speed of the magnetic stirrer to 880 r / min, stir for 5 min, filter the mixed solution using qualitative filter paper and a funnel, place it in a constant temperature water bath set at 25 °C, perform constant temperature filtration for 20 ± 5 min, rinse the electrode with the sample solution, and after the rinsing is complete, insert the electrode and temperature sensor into the sample solution. When the reading is stable and the temperature indicates 25 °C, record the pH value. The results are shown in Table 3.

[0076] 5) XRD test For the XRD test of the sodium ion cathode material in the examples of the present invention, an X’Pert PRO MPD analyzer was employed. Test principle: The Bragg equation reflects the relationship between the direction of the diffraction line and the crystal structure. For diffraction to occur, the Bragg equation: 2dsinθ = nλ (d: crystal plane spacing, θ: Bragg angle, λ: X-ray wavelength, n: reflection order) must be satisfied. When the sample is irradiated with X-rays, the scattered X-rays of each atom in the crystal interfere, generating a strong X-ray diffraction line in a specific direction. When the X-rays irradiate the sample from different angles, diffraction occurs on different crystal planes, and the detector receives the number of diffracted photons reflected from the crystal plane, thereby obtaining a spectrum of the relationship between the angle and the intensity. Test conditions: The light pipe uses a Cu target material, the wavelength is 1.54060, Be window, incident optical path: solar slit 0.04 rad, divergence slit 1 / 2°, aperture mask 10 mm, anti-scattering slit 1°, diffraction optical path: anti-scattering slit 8.0 mm, solar slit 0.04 rad, large Ni filter, scanning range 10~90°, scanning step 0.013°, dwell time per step 30.6 s, voltage 40 kV, current 40 mA. Powder sample preparation: Using a clean sampling spoon, put the powder into the groove of the slide glass (for large particle samples, the powder needs to be polished to <50μm). Place one side of the blade (>20mm) against the surface of the slide glass, lift the other side slightly (the included angle <10°), use the edge of the blade to flatten the surface of the powder sample, rotate the slide glass by 90°, flatten it again, repeat the scraping several times in both directions. There should be no texture on the surface of the sample. Remove the excess powder around the slide glass and put it into the powder X-ray diffractometer. Sample analysis: Open the sample file tested using the analysis software High-Score Plus. First, determine the background, select peak detection to confirm the peaks, perform repeated fitting, record the Williamson-Hall plot to calculate the grain size, select the corresponding phase to perform phase matching and unit cell refinement, and record the half-width of the (110) diffraction peak near the diffraction angle 2θ of 64.9°. The results are shown in Table 3.

[0077] 6) Moisture Measure with reference to GB / T 11133-2015 Karl Fischer coulometric titration method. Use an 899 Coulometer + 885 Compact Oven SC coulometer for testing. Weigh 0.5 - 0.8g of the sample using a moisture bottle with an accuracy of 0.0001g. The gas flow rate is 50 - 60ml / min, the heating temperature is 170°C, the initial drift ≤10μg / min, the end drift is 20μg / min, and the extraction time is 400s. The test results are retained to one decimal place, and the results are shown in Table 3.

[0078] 7) Compressed powder density [1] Place the sample circular mold on the stage of the electronic pressure tester. Slowly increase the pressure manually up to 1000kg, and then set the displacement and deformation to zero. [2] Put the sample bag on the electronic balance, subtract the weight of the container. Use a spoon (5.0000 ± 0.1000) to put the powder into the circular mold, gently shake it flat, and then place the upper pad of the mold on the sample. Note that in order to prevent the sample from spilling, both pads should face the sample with the non-cutting surface. [3] After filling the sample, place the mold on the stage of the electronic pressure tester, edit the program, increase the pressure to 8000 kg at a speed of 5 mm / min, maintain a constant voltage for 30 s, and then reduce the pressure to zero. [4] When the sample is under constant voltage until 8000 ± 10 kg (about 15 - 25 s after the pressure increase until reaching 8000 kg), record the pressure of the sample and read the sample height h, with an accuracy of 0.001 cm. [5] After the reading is completed, manually lower the stage of the electronic pressure tester and remove the sample with a sampler. [6] After removing the sample, clean the inside of the sample mold with a clean paper soaked in alcohol, ensure that the inside of the mold is clean, and the experiment is completed. [7] Calculate according to the results of the following formula and show the results in Table 3.

Equation

[0079] Perform an SEM test on the cathode material for the single - crystal sodium - ion battery in Example 1. As shown in Figure 1, it can be seen from Figure 1 that the material is composed of single - crystal particles, and the topography is polygonal and layered sheets.

[0080] Mix the cathode material for the single - crystal sodium - ion battery in Example 1, polyvinylidene fluoride (PVDF) as the binder, and conductive carbon black (S.P) in a weight ratio of 90:5:5, stir well to form a uniform slurry, coat it on an aluminum foil current collector, dry it, and cold - press it to make tabs. Then perform an SEM test on the tabs. As shown in Figure 9, it can be seen from Figure 9 that the material is still composed of single - crystal particles and no cracks occur on the surface of the material particles.

[0081] (Example 2) Weighed sodium carbonate, manganese carbonate, nickel carbonate, ferric oxide and copper oxide respectively with an elemental molar ratio of Na:Mn:Ni:Fe:Cu = 0.79:0.30:0.18:0.30:0.22 and a total weight of 1.46 kg, and added them to an ultra-high-speed multifunctional mixer and mixed at a rotation speed of 4000 r / min for 20 min. The uniformly mixed material was put into a muffle furnace and kept at a constant temperature of 905 °C for 12 h in an air atmosphere, and then naturally cooled, and pulverized with a jet mill at a pulverization pressure of 0.58 MPa to obtain a semi-finished product. Weighed 1.08 kg of the above semi-finished product and 0.005 kg of titanium oxide, added them to a ball mill can, ball milled at 35 Hz for 20 min, and put the uniformly mixed material into a muffle furnace and kept at a constant temperature of 400 °C for 3 h in an air atmosphere, and then naturally cooled, and pulverized with a jet mill at a pulverization pressure of 0.54 MPa, and sieved to obtain a positive electrode material C2 for single crystal sodium ion battery.

[0082] Adopted the component analysis method in Example 1 to measure that the chemical formula of the positive electrode material C2 for single crystal sodium ion battery is Na 0.79 Ni 0.18 Mn 0.295 Fe 0.30 Cu 0.22 Ti 0.005 O2.

[0083] Adopted the method in Example 1 to test the above positive electrode material, and the test results are shown in Table 3.

[0084] Performed an SEM test on the positive electrode material for single crystal sodium ion battery in Example 2. As shown in Figure 2, it can be seen from Figure 2 that the material is single crystal particles, and the topography is polygonal and layered sheet.

[0085] The cathode material for the single-crystal sodium-ion battery of Example 2, polyvinylidene fluoride (PVDF) as the binder, and conductive carbon black (S.P) were thoroughly mixed at a weight ratio of 90:5:5, stirred to form a uniform slurry, applied to an aluminum foil current collector, dried, cold-pressed to produce tabs, and an SEM test was performed on the tabs. As shown in Figure 10, it can be seen from Figure 10 that the material is still single-crystal particles and no cracks occur on the surface of the material particles.

[0086] (Example 3) Sodium carbonate, manganese(III) oxide, nickel oxalate, ferrous oxalate, and zinc oxide were weighed respectively at an elemental molar ratio of Na:Mn:Ni:Fe:Zn = 0.85:0.30:0.18:0.30:0.22 and a total weight of 1.844 kg, and then added to an ultra-high-speed multifunctional mixer and mixed at a rotation speed of 3500 r / min for 30 min. The uniformly mixed material was put into a muffle furnace and kept at a constant temperature of 910 °C for 10 h in an air atmosphere, and then naturally cooled. It was pulverized using a pneumatic grinder at a pulverization pressure of 0.63 MPa to obtain a semi-finished product. 1.11 kg of the above semi-finished product and 0.0025 kg of magnesium oxide were weighed, added to a ball mill can, ball milled at 45 Hz for 15 min, the uniformly mixed material was put into a muffle furnace and kept at a constant temperature of 500 °C for 5 h in an air atmosphere, and then naturally cooled. It was pulverized using a pneumatic grinder at a pulverization pressure of 0.56 MPa, sieved, and the cathode material C3 for the single-crystal sodium-ion battery was obtained.

[0087] Adopting the component analysis method in Example 1, the chemical formula of the cathode material C3 for the single-crystal sodium-ion battery was measured to be Na 0.88 Ni 0.18 Mn 0.30 Fe 0.297 Zn 0.22 Mg 0.003 O2.

[0088] Adopting the method in Example 1 to test the above cathode material, the test results are shown in Table 3.

[0089] The SEM test was performed on the positive electrode material for the single-crystalline sodium-ion battery of Example 3. As shown in FIG. 3, it can be seen from FIG. 3 that the material is composed of single-crystalline particles, and the topography is polygonal and layered sheets.

[0090] The positive electrode material for the single-crystalline sodium-ion battery of Example 3, polyvinylidene fluoride (PVDF) as a binder, and conductive carbon black (S.P) were thoroughly mixed at a weight ratio of 90:5:5, stirred to form a uniform slurry, applied to an aluminum foil current collector, dried, pressed to produce tabs, and the tabs were subjected to SEM test. As shown in FIG. 11, it can be seen from FIG. 11 that the material is still composed of single-crystalline particles and no cracks occur on the surface of the material particles.

[0091] (Example 4) With an elemental molar ratio of Na:Mn:Ni:Fe:Zn = 0.88:0.30:0.18:0.30:0.22 and a total weight of 1.844 kg, sodium carbonate, manganese(III) oxide, nickel oxalate, ferrous oxalate, and zinc oxide were weighed respectively, and added to an ultra-high-speed multifunctional mixer and mixed at a rotation speed of 3500 r / min for 30 min. The uniformly mixed material was placed in a muffle furnace and kept at a constant temperature of 920 °C for 15 h in an air atmosphere, and then naturally cooled. It was pulverized using an airflow pulverizer at a pulverization pressure of 0.68 MPa to obtain a semi-finished product.

[0092] 0.025 kg of aluminum nitrate was weighed, and the weighed aluminum nitrate and pure water were prepared into an aluminum nitrate solution at a mass ratio of 1:3 for use. 1.11 kg of the above semi-finished product was weighed, added to water, stirred for 10 min, the prepared aluminum nitrate solution was added thereto, and stirring was continued for 10 min. Then, it was suction filtered, dried, the dried material was placed in a muffle furnace, kept at a constant temperature of 600 °C for 6 h in an air atmosphere, and then naturally cooled. It was pulverized using an airflow pulverizer at a pulverization pressure of 0.60 MPa, sieved, and the positive electrode material C4 for the single-crystalline sodium-ion battery was obtained.

[0093] Adopting the component analysis method in Example 1, the chemical formula of the positive electrode material C4 for the single-crystalline sodium-ion battery is Na 0.88 Ni 0.18 Mn0.297 Fe 0.291 Zn 0.22 Al 0.012 It was measured to be O2.

[0094] The above positive electrode material was tested by adopting the method in Example 1, and the test results are shown in Table 3.

[0095] An SEM test was conducted on the positive electrode material for the single crystal sodium ion battery of Example 4. As shown in Figure 4, it can be seen from Figure 4 that the material is single crystal particles, and the topography is polygonal and layered sheets.

[0096] The positive electrode material for the single crystal sodium ion battery of Example 4, polyvinylidene fluoride (PVDF) as a binder, and conductive carbon black (S.P) were sufficiently mixed at a weight ratio of 7:2:1, stirred to form a uniform slurry, applied to an aluminum foil current collector, dried and pressed to produce tabs. An SEM test was conducted on the tabs. As shown in Figure 12, it can be seen from Figure 12 that the material is still single crystal particles and no cracks occur on the surface of the material particles.

[0097] (Example 5) With an element molar ratio of Na:Mn:Ni:Fe:Al = 0.81:0.33:0.33:0.33:0.01 and a total weight of 1.56 kg, the corresponding weights of sodium carbonate, manganese carbonate, nickel carbonate, ferric oxide and aluminum oxide were weighed respectively, and added to an ultra-high speed multi-functional mixer and mixed at a rotation speed of 2800 r / min for 30 min. The uniformly mixed material was put into a muffle furnace and kept at a constant temperature of 930 °C for 10 h in an air atmosphere, and then naturally cooled. It was pulverized with an air flow pulverizer at a pulverization pressure of 0.65 MPa to obtain a semi-finished product. 1.068 kg of the above semi-finished product and 0.0074 kg of boron oxide were weighed, added to a ball mill can, ball milled at 40 Hz for 10 min, and the uniformly mixed material was put into a muffle furnace, kept at a constant temperature of 500 °C for 3 h in an air atmosphere, and then naturally cooled. It was pulverized with an air flow pulverizer at a pulverization pressure of 0.56 MPa, sieved, and the positive electrode material C5 for the single crystal sodium ion battery was obtained.

[0098] The chemical formula of the cathode material C5 for the single-crystal sodium-ion battery was measured to be Na 0.81 Ni 0.33 Mn 0.33 Fe 0.31 Al 0.01 B 0.02 O2 by adopting the component analysis method in Example 1.

[0099] The above cathode material was tested by adopting the method in Example 1, and the test results are shown in Table 3.

[0100] The cathode material for the single-crystal sodium-ion battery of Example 5 was subjected to an SEM test. As shown in Figure 5, it can be seen from Figure 5 that the material is single-crystal particles and the topography is polygonal and layered sheets.

[0101] The cathode material for the single-crystal sodium-ion battery of Example 5, polyvinylidene fluoride (PVDF) as a binder, and conductive carbon black (S.P) were thoroughly mixed at a weight ratio of 7:2:1, stirred to form a uniform slurry, applied to an aluminum foil current collector, dried and pressed to make tabs. An SEM test was performed on the tabs. As shown in Figure 13, it can be seen from Figure 13 that the material is still single-crystal particles and no cracks occur on the surface of the material particles.

[0102] (Example 6) Sodium carbonate, manganese carbonate, nickel carbonate, ferrous oxalate, and zinc oxide were weighed respectively at an element molar ratio of Na:Mn:Ni:Fe:Zn = 0.84:0.34:0.25:0.30:0.11 and a total weight of 1.77 kg, and then added to an ultra-high-speed multifunctional mixer and mixed at a rotation speed of 3000 r / min for 30 min. The uniformly mixed material was put into a muffle furnace and kept at a constant temperature of 980 °C for 9 hours in an air atmosphere, and then naturally cooled. It was pulverized using an air flow pulverizer at a pulverization pressure of 0.66 MPa to obtain a semi-finished product.

[0103] Weigh 1.086 kg of the above semi-finished product and 0.048 kg of niobium pentoxide, add them to a ball mill can, perform ball milling at 40 Hz for 20 min, put the uniformly mixed material into a muffle furnace, keep it at a constant temperature of 600 °C for 7 hours in an air atmosphere, and then cool it naturally. Use an airflow pulverizer to pulverize at a pulverization pressure of 0.58 MPa, screen it, and obtain the positive electrode material C6 for single crystal sodium ion batteries.

[0104] Adopt the component analysis method in Example 1 to measure that the chemical formula of the positive electrode material C6 for single crystal sodium ion batteries is Na 0.84 Ni 0.25 Mn 0.34 Fe 0.295 Zn 0.11 Nb 0.005 O2.

[0105] Adopt the method in Example 1 to test the above positive electrode material, and the test results are shown in Table 3.

[0106] Perform an SEM test on the positive electrode material for single crystal sodium ion batteries in Example 6. As shown in Figure 6, it can be seen from Figure 6 that the material is single crystal particles, and the topography is polygonal and layered sheets.

[0107] Mix the positive electrode material for single crystal sodium ion batteries in Example 6 with polyvinylidene fluoride (PVDF), which is a binder, and conductive carbon black (S.P) in a weight ratio of 7:2:1, stir well to form a uniform slurry, coat it on an aluminum foil current collector, dry it and press it to make tabs, and perform an SEM test on the tabs. As shown in Figure 14, it can be seen from Figure 14 that the material is still single crystal particles and no cracks occur on the surface of the material particles.

[0108] (Example 7) Sodium carbonate, manganese carbonate, and iron(III) oxide were weighed at an elemental molar ratio of Na:Mn:Fe = 0.84:0.5:0.5 and a total weight of 1.61 kg, and then added to an ultra-high-speed multifunctional mixer and mixed at a rotation speed of 3700 r / min for 25 min. The uniformly mixed material was placed in a muffle furnace and kept at 875 °C for 9 h under an air atmosphere, and then naturally cooled. It was pulverized using a jet mill at a pulverization pressure of 0.66 MPa to obtain a semi-finished product.

[0109] 1.072 kg of the above semi-finished product and 0.045 kg of zirconium oxide were weighed, added to a ball mill can, ball-milled at 45 Hz for 15 min, and the uniformly mixed material was placed in a muffle furnace and kept at 730 °C for 7 h under an air atmosphere, and then naturally cooled. It was pulverized using a jet mill at a pulverization pressure of 0.58 MPa, sieved, and the positive electrode material C7 for single-crystal sodium-ion batteries was obtained.

[0110] Using the component analysis method in Example 1, the chemical formula of the positive electrode material C7 for single-crystal sodium-ion batteries was measured to be Na 0.84 Mn 0.497 Fe 0.5 Zr 0.003 O2.

[0111] The positive electrode material for single-crystal sodium-ion batteries in Example 7 was subjected to an SEM test. As shown in Fig. 7, it can be seen from Fig. 7 that the material is composed of single-crystal particles, and the topography is polygonal and layered sheets.

[0112] The positive electrode material for single-crystal sodium-ion batteries in Example 7, polyvinylidene fluoride (PVDF) as a binder, and conductive carbon black (S.P) were thoroughly mixed at a weight ratio of 7:2:1, stirred to form a uniform slurry, applied to an aluminum foil current collector, dried, pressed to make tabs, and the tabs were subjected to an SEM test. As shown in Fig. 15, it can be seen from Fig. 15 that the material is still composed of single-crystal particles and no cracks occur on the surface of the material particles.

[0113] (Example 8) With an elemental molar ratio of Na:Mn:Ni:Fe:Ti = 0.91:0.1:0.42:0.32:0.16 and a total weight of 1.79 kg, sodium carbonate, manganese carbonate, nickel carbonate, ferrous oxalate, and titanium dioxide were weighed respectively, and then added to an ultra-high-speed multifunctional mixer and mixed at a rotational speed of 3300 r / min for 35 min. The uniformly mixed material was put into a muffle furnace and kept at a constant temperature of 890 °C for 10 h under an oxygen atmosphere, and then cooled naturally. It was pulverized using a jet mill at a pulverization pressure of 0.62 MPa to obtain a semi-finished product.

[0114] 0.025 kg of aluminum nitrate was weighed, and the weighed aluminum nitrate and pure water were used to prepare an aluminum nitrate solution at a mass ratio of 1:3 for use. 1.072 kg of the above semi-finished product was weighed, added to water and stirred for 10 min, the prepared aluminum nitrate solution was added thereto, and then stirred continuously for 10 min, suction filtered, dried, and the dried material was put into a muffle furnace and kept at a constant temperature of 550 °C for 4 h under an oxygen atmosphere, and then cooled naturally. It was pulverized using a jet mill at a pulverization pressure of 0.60 MPa, sieved, and the positive electrode material C8 for single-crystalline sodium-ion batteries was obtained.

[0115] The chemical formula of the positive electrode material C8 for single-crystalline sodium-ion batteries was measured to be Na 0.91 Ni 0.42 Mn 0.1 Fe 0.308 Ti 0.16 Al 0.012 O2 by adopting the component analysis method in Example 1.

[0116] The positive electrode material for single-crystalline sodium-ion batteries in Example 8 was subjected to an SEM test. As shown in Figure 8, it can be seen from Figure 8 that the material is composed of single-crystalline particles, and the topography is polygonal and layered sheet.

[0117] The positive electrode material for a single crystal sodium ion battery of Example 8, polyvinylidene fluoride (PVDF) as a binder, and conductive carbon black (S.P) were thoroughly mixed at a weight ratio of 7:2:1, stirred to form a uniform slurry, applied to an aluminum foil current collector, dried, pressed to produce tabs, and subjected to an SEM test on the tabs. As shown in Figure 16, it can be seen from Figure 16 that the material is still single crystal particles and no cracks occur on the surface of the material particles.

[0118] (Example 9) With an element molar ratio of Na:Mn:Ni:Fe:Zn = 0.88:0.30:0.18:0.30:0.22 and a total weight of 1.844 kg, sodium carbonate, manganese(III) oxide, nickel oxalate, ferrous oxalate, and zinc oxide were weighed respectively, and then added to an ultra-high speed multi-functional mixer and mixed at a rotation speed of 3500 r / min for 30 min. The uniformly mixed material was put into a muffle furnace and kept at a constant temperature of 900 °C for 10 h in an air atmosphere, and then naturally cooled. It was pulverized using an air flow pulverizer at a pulverization pressure of 0.63 MPa, sieved, and the positive electrode material C9 for a single crystal sodium ion battery was obtained.

[0119] Adopting the component analysis method in Example 1, the chemical formula of the positive electrode material C9 for a single crystal sodium ion battery was measured to be Na 0.88 Ni 0.18 Mn 0.30 Fe 0.30 Zn 0.22 O2.

[0120] Adopting the method in Example 1 to test the above positive electrode material, the test results are shown in Table 3.

[0121] An SEM test was conducted on the positive electrode material for a single crystal sodium ion battery of Example 9. As shown in Figure 17, it can be seen from Figure 17 that the material is single crystal particles and the topography is polygonal and layered sheets.

[0122] The cathode material for a single-crystalline sodium-ion battery of Example 9, polyvinylidene fluoride (PVDF) as a binder, and conductive carbon black (S.P) were thoroughly mixed at a weight ratio of 7:2:1, stirred to form a uniform slurry, coated on an aluminum foil current collector, dried, pressed to produce tabs, and SEM tests were performed on the tabs. As shown in Figure 18, it can be seen from Figure 18 that the material is still single-crystalline particles and no cracks occur on the surface of the material particles.

[0123]

Table 3

[0124] As can be seen from Table 3, in the powder X-ray diffraction spectra (XRD) of the cathode materials for single-crystalline sodium-ion batteries manufactured in Examples 1 to 8, the full width at half maximum FWHM(110) of the (110) diffraction peak at a diffraction angle 2θ of around 64.9° is 0.15 to 0.27, the moisture mass content is 1200 ppm or less, the pH is less than 12.60 for all, the specific surface area is 0.31 to 0.69 m 2 / g, the particle size D V 50 is 3.4 to 10.2 μm, and the tap density is 2.95 to 3.83 g / cm 3 . Example 9 was not subjected to a coating treatment, the moisture mass content was 2145 ppm, much larger than 1500 ppm, the pH was 12.92, and larger than 12.6.

[0125] (Experimental Example 1) Manufacture and performance evaluation of a sodium-ion battery.

[0126] A CR2430 button-type battery was manufactured according to the following method. Positive electrode manufacturing: The positive electrode materials for single-crystal sodium-ion batteries manufactured in Examples 1 to 9 of the present invention, polyvinylidene fluoride (PVDF) as a binder, and conductive carbon black (S.P) were thoroughly mixed at a weight ratio of 7:2:1, stirred to form a uniform slurry, applied to an aluminum foil current collector, dried, pressed to form tabs, denoted as PE-C1, PE-C2, PE-C3, PE-C4, PE-C5, PE-C6, PE-C7, PE-C8, and PE-C9. The pressed positive electrode tabs were punched out, weighed, fired, and then battery assembly was carried out in a vacuum glove box. First, the bottom of the button-type battery case was placed, a foamed nickel (2.5 mm) and a negative electrode sodium metal sheet (manufacturer: Shenzhen Youyan Technology Co., Ltd.) were placed on the bottom of the case, 0.5 g of electrolyte was injected in an environment with a relative humidity of less than 1.5%. The electrolyte adopted a mixed solvent with a mass ratio of ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) of 1:1:1, and the electrolyte was a 1 mol / L sodium hexafluorophosphate solution. A separator and a positive electrode tab were placed, and then the button-type battery case was covered and sealed to obtain a button-type battery with model number CR2430, denoted as BA-C1, BA-C2, BA-C3, BA-C4, BA-C5, BA-C6, BA-C7, BA-C8, and BA-C9.

[0127] The batteries were subjected to performance tests on a battery test system according to the following method, and the results are shown in Table 4. 1) Capacity test The manufactured button-type batteries were attached to the test bench and the test program was started. Setting steps: The test temperature was set to 25°C, left standing for 4 hours, charged at a constant current of 0.1C to 4.0V, paused, left standing, and then discharged at a constant current of 0.1C to 2.0V to obtain the capacity at the said current and voltage. 2) Cycle test Attach the battery that has undergone the above capacity test to the test bench, start the test program, and set the steps as follows: set the test temperature to 45°C, let it stand for 4 hours, charge at a constant current of 0.5C until 4.0V, charge at a constant voltage of 4.0V for 2h, let it stand for 5 minutes, then discharge at a constant current of 0.5C until the cut-off voltage of 2.0V, let it stand for 5 minutes, repeat the steps starting from the previous constant current charging, conduct a cycle test, and the capacity retention rate corresponding to the number of cycles can be obtained.

[0128]

Table 4

[0129] As can be seen from Table 4, the sodium-ion batteries manufactured by adopting the cathode materials for single-crystalline sodium-ion batteries produced in Examples 1 to 8 have a capacity of 115.9 to 164.0 mAh / g under a current of 0.1C and a voltage of 4.2V (the cut-off voltage is 2.0V), and the capacity retention rate is 80.2 to 90.5% after 50 cycles under the conditions of 4.0V to 2.0V and 0.5C / 0.5C. Example 9 was not subjected to the coating treatment, and the capacity retention rate was only 74.84% after 50 cycles under the conditions of 4.0V to 2.0V and 0.5C / 0.5C. It can also be seen from Figure 20 that the capacity retention rate during the cycle test of the sodium-ion batteries manufactured by adopting the cathode materials for single-crystalline sodium-ion batteries produced in Examples 1 to 8 is significantly better than that of Example 9.

[0130] After 50 cycles of Battery BA-C1, disassemble the battery, take out the positive electrode tab, and conduct an SEM test. As shown in Figure 19, it can be seen from Figure 19 that even after cycling, the single-crystalline particles have no cracks and remain as complete particles.

[0131] The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any way. Modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0132] (Supplementary Note) (Supplementary Note 1) A cathode material for a single crystal sodium ion battery, The cathode material for the single crystal sodium ion battery contains elements having a composition represented by Chemical Formula 1, wherein the Chemical Formula 1 is Na 1+a Ni 1-x-y-z-c Mn x Fe y M z N c O2, where -0.40 ≦ a ≦ 0.25, 0.08 ≦ x ≦ 0.5, 0.05 ≦ y ≦ 0.5, 0 ≦ z < 0.26, 0 < c < 0.1, M is a doping element, and N is a coating element, both M and N are selected from one or more of the elements 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, A cathode material for a single crystal sodium ion battery, characterized in that.

[0133] (Appendix 2) -0.40 ≦ a ≦ 0, 0.15 ≦ x ≦ 0.5, 0.15 ≦ y ≦ 0.5, A cathode material for a single crystal sodium ion battery according to Appendix 1, characterized in that.

[0134] (Appendix 3) M is selected from one or more of Zn, Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, or Cu, A cathode material for a single crystal sodium ion battery according to Appendix 1, characterized in that.

[0135] (Appendix 4) M is one or more of Zn, Al, B, Ti, Ca, Y, Mg, Nb, Zr, or Cu, A cathode material for a single crystal sodium ion battery according to Appendix 1, characterized in that.

[0136] (Appendix 5) -0.40 ≦ a ≦ 0.25, 0.08 ≦ x ≦ 0.5, 0.05 ≦ y ≦ 0.5, 0 < c < 0.1, 0 ≦ z ≦ 0.13 The positive electrode material for a single-crystal sodium ion battery according to Addendum 1, characterized in that

[0137] (Addendum 6) The N is one or more selected from Al, Ti, Co, Mn, Y, B, F, P, Nb, Zr, W, Sr or Mg The positive electrode material for a single-crystal sodium ion battery according to Addendum 1, characterized in that

[0138] (Addendum 7) The N is one or more of Al, Ti, B, Nb or Mg The positive electrode material for a single-crystal sodium ion battery according to Addendum 1, characterized in that

[0139] (Addendum 8) -0.40 ≦ a ≦ 0.25, 0.08 ≦ x ≦ 0.5, 0.05 ≦ y ≦ 0.5, 0 ≦ z < 0.26, 0 < c < 0.05 The positive electrode material for a single-crystal sodium ion battery according to Addendum 1, characterized in that

[0140] (Addendum 9) The positive electrode material for the single-crystal 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 spherical, pseudo-spherical, polygonal or layered sheet The positive electrode material for a single-crystal sodium ion battery according to Addendum 1, characterized in that

[0141] (Addendum 10) In the powder X-ray diffraction spectrum (XRD) of the positive electrode material for the single-crystal sodium ion battery, the full width at half maximum FWHM(110) of the diffraction peak at a diffraction angle 2θ of around 64.9° is 0.08 - 0.35 The positive electrode material for a single-crystal sodium ion battery according to any one of Addenda 1 to 9, characterized in that

[0142] (Supplementary Note 11) The tap density of the single-crystalline sodium-ion battery cathode material under a pressure of 7000 to 9000 kg is 2.8 to 4.2 g / cm 3 is as follows: The single-crystalline sodium-ion battery cathode material according to any one of Supplementary Notes 1 to 9, characterized in that:

[0143] (Supplementary Note 12) The water mass content of the single-crystalline sodium-ion battery cathode material is less than 1500 ppm, and / or the pH value of the single-crystalline sodium-ion battery cathode material is within 12.6. The single-crystalline sodium-ion battery cathode material according to any one of Supplementary Notes 1 to 9, characterized in that:

[0144] (Supplementary Note 13) The specific surface area of the single-crystalline sodium-ion battery cathode material is 0.35 to 1.2 m 2 / g, and / or the particle size D V 50 of the single-crystalline sodium-ion battery cathode material is 2.00 to 16.0 μm. The single-crystalline sodium-ion battery cathode material according to any one of Supplementary Notes 1 to 9, characterized in that:

[0145] (Supplementary Note 14) Step (1) of mixing raw materials including a sodium source compound, a manganese source compound, and an iron source compound, and adding a nickel source compound and an M source compound as necessary, and then performing the first sintering and pulverizing to obtain a semi-finished product; Step (2) of mixing the semi-finished product obtained in Step (1) and the raw materials of the N source compound, then performing the second sintering and pulverizing to obtain a single-crystalline sodium-ion battery cathode material. The method for manufacturing a single-crystalline sodium-ion battery cathode material according to any one of Supplementary Notes 1 to 9, characterized in that:

[0146] (Supplementary Note 15) The first sintering temperature in step (1) is 860 - 990 °C, the second sintering temperature in step (2) is 350 - 900 °C, and / or the pulverization pressure in steps (1) and (2) is both 0.1 - 1 MPa. The manufacturing method according to appendix 14, characterized by this.

[0147] (Appendix 16) The sodium source compound contains a salt and / or hydroxide containing sodium element, and / or The manganese source compound contains one or more of an oxide, hydroxide or salt containing manganese element, and / or The nickel source compound contains one or more of an oxide, hydroxide or salt containing nickel element, and / or The iron source compound contains one or more of an oxide, hydroxide or salt containing iron element, and / or The M source compound contains an oxide and / or salts containing M element, and / or The N source compound contains an oxide and / or salts containing N element. The manufacturing method according to appendix 14, characterized by this.

[0148] (Appendix 17) The active material is a cathode material for a single-crystal sodium-ion battery described in any one of appendices 1 - 13. The cathode for a sodium-ion battery, characterized by this.

[0149] (Appendix 18) Including the cathode for a sodium-ion battery described in appendix 17. The sodium-ion battery, characterized by this.

Claims

1. A cathode material for a single crystal sodium ion battery, wherein the cathode material for the single crystal sodium ion battery contains elements having a composition represented by Chemical Formula 1, The chemical formula 1 is Na １＋ａ Ni １－ｘ－ｙ－ｚ－ｃ Mn ｘ Fe ｙ M ｚ N ｃ O ２ wherein -0.40 ≤ a ≤ 0.25, 0.08 ≤ x ≤ 0.5, 0.05 ≤ y ≤ 0.5, 0 < z < 0.26, 0 < c < 0.1, M is a doping element, N is a coating element, 1 - x - y - z - c > 0, and the coating element N forms a coating layer on the positive electrode material, wherein both M and N are one or more selected from the group consisting of 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; in the powder X-ray diffraction spectrum (XRD) of the cathode material for the single crystal sodium ion battery, the full width at half maximum FWHM(110) of the (110) diffraction peak at a diffraction angle 2θ of around 64.9° is from 0.08 to 0.35, a cathode material for a single crystal sodium ion battery, characterized in that.

2. -0.40 ≤ a ≤ 0, 0.15 ≤ x ≤ 0.5, 0.15 ≤ y ≤ 0.5, a cathode material for a single crystal sodium ion battery according to Claim 1, characterized in that.

3. wherein M is one or more selected from the group consisting of 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, a cathode material for a single crystal sodium ion battery according to Claim 1, characterized in that.

4. wherein M is one or more selected from the group consisting of Zn, Al, B, Ti, Ca, Y, Mg, Nb, Zr, and Cu, a cathode material for a single crystal sodium ion battery according to Claim 1, characterized in that.

5. -0.40 ≤ a ≤ 0.25, 0.08 ≤ x ≤ 0.5, 0.05 ≤ y ≤ 0.5, 0 < c < 0.1, 0 < z ≤ 0.13, a cathode material for a single crystal sodium ion battery according to Claim 1, characterized in that.

6. wherein N is one or more selected from the group consisting of Al, Ti, Co, Mn, Y, B, F, P, Nb, Zr, W, Sr, and Mg, a cathode material for a single crystal sodium ion battery according to Claim 1, characterized in that.

7. wherein N is one or more selected from the group consisting of Al, Ti, B, Nb, and Mg, a cathode material for a single crystal sodium ion battery according to Claim 1, characterized in that.

8. -0.40 ≤ a ≤ 0.25, 0.08 ≤ x ≤ 0.5, 0.05 ≤ y ≤ 0.5, 0 < z < 0.26, 0 < c < 0.05, a cathode material for a single crystal sodium ion battery according to Claim 1, characterized in that.

9. When the positive electrode material for the single crystal 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 spherical, pseudo-spherical, polygonal or layered sheet, The positive electrode material for a single crystal sodium ion battery according to claim 1, characterized in that.

10. The tap density of the positive electrode material for the single-crystalline sodium ion battery under a pressure of 7000 to 9000 kg is 2.8 to 4.2 g / cm on an area of 3.14 cm2 ３ is The positive electrode material for a single crystal sodium ion battery according to any one of claims 1 to 9, characterized in that.

11. The moisture mass content of the positive electrode material for the single crystal sodium ion battery is less than 1500 ppm, The positive electrode material for a single crystal sodium ion battery according to any one of claims 1 to 9, characterized in that.

12. 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 / or the particle size D Ｖ 50 of the positive electrode material for the single-crystal sodium-ion battery is 2.00 to 16.0 μm. The positive electrode material for a single crystal sodium ion battery according to any one of claims 1 to 9, characterized in that.

13. Mixing raw materials including a sodium source compound, a manganese source compound and an iron source compound, and adding a nickel source compound and an M source compound as required, and performing the first sintering, pulverizing to obtain a semi-finished product Step (1); Step (2) of performing a second sintering after mixing the semi-finished product obtained in step (1) and the raw material of the N source compound, and pulverizing to obtain a positive electrode material for a single crystal sodium ion battery. The method for manufacturing a positive electrode material for a single crystal sodium ion battery according to any one of claims 1 to 9, characterized in that.

14. The first sintering temperature in step (1) is 860 to 990 ° C, the second sintering temperature in step (2) is 350 to 900 ° C, and / or the pulverization pressures in step (1) and step (2) are both 0.1 to 1 MPa, The manufacturing method according to claim 13, characterized in that.

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 oxides, hydroxides or salts containing manganese element, and / or The nickel source compound includes one or more of oxides, hydroxides or salts containing nickel element, and / or The iron source compound includes one or more of oxides, hydroxides or salts containing iron element, and / or The M source compound includes oxides and / or salts containing M element, and / or The N source compound includes oxides and / or salts containing N element. The manufacturing method according to claim 13, characterized in that...

16. The active material is the single-crystal sodium-ion battery positive electrode material according to any one of claims 1 to 9, The positive electrode for a sodium-ion battery, characterized in that...

17. Including the positive electrode for a sodium-ion battery according to claim 16, The sodium-ion battery, characterized in that...

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