Positive electrode material for sodium ion batteries, its manufacturing method and application

Abstract

To provide a sodium ion battery cathode material, and a preparation method therefor and application thereof.SOLUTION: A general chemical formula of a cathode material is NamNixFeyMnzO2. In the general chemical formula, 0.1≤x≤0.25, 0.5≤y≤0.8, 0.1≤z≤0.25, 0.8≤m≤1.1, 0.95≤x / z≤1.05, and x+y+z=1, m, x, y and z are molar percentages of corresponding elements, respectively, and each component in the general chemical formula satisfies charge conservation and stoichiometry conservation. A preparation method includes the steps of: preparing a precursor including a nickel source, an iron source and a manganese source with required stoichiometry by a co-precipitation method; mixing the precursor of the nickel source, the iron source and the manganese source with a sodium source in a certain proportion, and then adding a doping element for primary sintering to obtain a doped sodium ion battery cathode material; and carrying out secondary sintering on the doped sodium ion battery cathode material and a coating to obtain a final sodium ion battery cathode material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the technical field of sodium ion batteries, and in particular to a positive electrode material for sodium ion batteries, its manufacturing method and application. [Background technology]

[0002] With the rapid development of the new energy industry, the lithium resources used to manufacture lithium-ion batteries are far from meeting the explosively increasing demand. Sodium-ion batteries, which have similar energy storage mechanisms and abundant storage capacity to lithium-ion batteries, are becoming a strong competitor to replace lithium-ion batteries in large-scale energy storage systems.

[0003] Layered sodium ion batteries are considered to be the most potential positive electrode material for sodium ion batteries. For example, CN113258060B discloses a high nickel layered oxide material for sodium ion batteries, its manufacturing method and application. The high nickel layered oxide material for sodium ion batteries has the general chemical formula Na x Ni a Fe b Mn c M d O 2±δ where Ni, Fe, and Mn are transition metal elements, and M is an element that dopes and substitutes the transition metal site. In the oxide material structure, the ions at the transition metal site form an octahedral structure with six adjacent oxygen atoms, and are arranged alternately with octahedral NaO6 layers, forming an O3-type high-nickel layered oxide material for sodium ion batteries with a space group of R-3m. M specifically represents Li + , Mg 2+ , Ca 2+ , Cu 2+ , Zn 2+ , Al 3+ , B 3+ , Co 3+ , V 3+ , Y 3+ , Ti 4+ , Zr 4+ , Sn 4+ , Mo4+ , Si 4+ , Ru 4+ , Nb 5+ , Sb 5+ , Mo 5+ , Mo 6+ , W 6+ wherein x, a, b, c, d, and 2+δ are the mole percentages of the corresponding elements, and each component in the general chemical formula satisfies the conservation of charge and the conservation of stoichiometry, and the following relationships are satisfied: 0.67≦x≦1, 0.5≦a<1, 0.01≦b≦0.35, 0.01≦c≦0.35, 0≦d≦0.3, 0≦δ≦0.1.

[0004] However, these nickel-containing layered transition metal oxides, which are used as cathode materials for sodium-ion batteries, have problems such as high cost, high residual alkalinity on the surface, and low cycle stability, limiting their large-scale application. Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above, the present invention aims to solve at least one of the technical problems existing in the prior art. The present invention provides a positive electrode material for sodium ion batteries, a manufacturing method thereof, and applications thereof. In the present invention, by controlling the composition and particle morphology of the transition metal elements iron and manganese, it is possible to maintain high capacity of the positive electrode material while maintaining low nickel, and reduce free sodium ions on the surface, thereby obtaining a low-nickel sodium ion battery positive electrode material with high capacity, low residual alkalinity, and high stability. Furthermore, the manufacturing method is simple and suitable for large-scale industrial production. [Means for solving the problem]

[0006] Thus, according to a first aspect, an embodiment of the present invention is a compound having the general chemical formula Na m Ni x Fe y Mn zO2, where 0.1≦x≦0.25, 0.5≦y≦0.8, 0.1≦z≦0.25, 0.8≦m≦1.1, 0.95≦x / z≦1.05, x+y+z=1, m, x, y, and z are the mole percentages of the corresponding elements, and each component in the general chemical formula satisfies the conservation of charge and conservation of stoichiometry.

[0007] Preferably, the positive electrode material for sodium ion batteries contains a doping element A and has the general chemical formula Na m Ni x Fe y Mn z A p O2, where 0.001≦p≦0.05, 0.1≦x≦0.25, 0.5≦y≦0.8, 0.1≦z≦0.25, 0.8≦m≦1.1, 0.95≦x / z≦1.05, x+y+z=1, m, x, y, z, and p are the mole percentages of the corresponding elements, and each component in the general chemical formula satisfies the conservation of charge and the conservation of stoichiometry. The doping element A is one or more of the following elements: lithium, magnesium, calcium, copper, zinc, aluminum, boron, cobalt, vanadium, yttrium, titanium, zirconium, tin, molybdenum, silicon, ruthenium, niobium, antimony, and tungsten.

[0008] According to a second aspect, an embodiment of the present invention provides a method for producing the sodium-ion battery cathode material according to the first aspect, the method including the steps of: preparing a precursor containing a nickel source, an iron source, and a manganese source with a desired stoichiometry by a co-precipitation method; mixing the precursors of the nickel source, the iron source, and the manganese source with the sodium source in a certain ratio, adding a doping element, and performing primary sintering to obtain a doped sodium-ion battery cathode material; and performing secondary sintering of the doped sodium-ion battery cathode material and a coating to obtain a final sodium-ion battery cathode material.

[0009] Preferably, the iron source is one or more of ferrous sulfate, hydrous ferrous sulfate, ferrous nitrate, and ferrous chloride; the manganese source is one or more of manganese sulfate, manganese nitrate, manganese chloride, and manganese acetate; and the nickel source is one or more of nickel chloride, nickel oxide, nickel nitrate, nickel sulfate, and nickel sulfamate.

[0010] Preferably, the step of producing a precursor containing a nickel source, an iron source, and a manganese source with a desired stoichiometry by a coprecipitation method includes the steps of preparing an aqueous solution of the nickel source, the iron source, and the manganese source in a stoichiometric ratio; preparing an aqueous ammonia solution and a sodium hydroxide solution with a certain concentration; feeding the aqueous solution, the aqueous ammonia solution, and the sodium hydroxide solution into a reaction vessel at a constant flow rate, controlling the pH value of the reaction system to 10 to 10.5, and performing a coprecipitation reaction to obtain a reaction product; and washing, suction filtering, and drying the reaction product to obtain the precursors of the nickel source, the iron source, and the manganese source.

[0011] Preferably, the molar ratios of the nickel source, the iron source, and the manganese source added satisfy n(Ni):n(Fe):n(Mn)=x:y:z, the concentration of the aqueous ammonia solution is 25%, the concentration of the sodium hydroxide solution is 15%, the rotation speed is 300 to 500 rpm, the temperature is 40 to 80°C, the flow rates of the aqueous solutions are 1.0 L / h, the flow rate of the aqueous ammonia solution is 0.8 L / h, and the flow rate of the sodium hydroxide solution is 2.0 L / h.

[0012] Preferably, the molar ratio of the precursors of the nickel source, iron source, and manganese source to the sodium source is 1:(0.8 to 1.1), and the sodium source is one or more of sodium carbonate, sodium hydrogencarbonate, sodium sulfate, sodium chloride, sodium perchlorate, sodium nitrate, sodium phosphate, and sodium hydrogen phosphate.

[0013] Preferably, the doping element may be one or more of lithium, magnesium, calcium, copper, zinc, aluminum, boron, cobalt, vanadium, yttrium, titanium, zirconium, tin, molybdenum, silicon, ruthenium, niobium, antimony, and tungsten, and the primary sintering process is to heat to 480°C at a heating rate of 3°C / min and keep the temperature for 4 hours.

[0014] Preferably, the coating is one or more of calcium oxide, cobalt oxyhydroxide, aluminum oxide, sodium molybdate, lanthanum oxide, aluminum metaphosphate, titanium oxide, magnesium oxide, zirconium oxide, sodium titanate, cobalt oxide, aluminum fluoride, chromium oxide, zinc oxide, strontium oxide, copper oxide, and tungsten oxide, and the secondary sintering process is heating to 850°C at a heating rate of 4°C / min and maintaining the temperature for 10 hours.

[0015] According to a third aspect, an embodiment of the present invention provides a sodium ion battery including the sodium ion battery positive electrode material according to the first aspect. [Effects of the Invention]

[0016] The positive electrode material for sodium ion batteries according to the present invention, its manufacturing method and application, uses a low-nickel layered oxide and controls the composition and particle morphology of the transition metal elements iron and manganese, thereby maintaining a high capacity of the positive electrode material while maintaining a low nickel content and reducing the free sodium ions on the surface, resulting in a positive electrode material for sodium ion batteries with high capacity, low residual alkalinity and high stability. Furthermore, the manufacturing method is simple and suitable for large-scale industrial production. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a flowchart of a method for manufacturing a positive electrode material for a sodium ion battery according to an embodiment of the present invention. [Figure 2]1 is a flowchart of step S1 of a method for producing a positive electrode material for a sodium ion battery according to an embodiment of the present invention. [Figure 3] FIG. 1 is an SEM image of a positive electrode material for a sodium ion battery produced in Reference Example 1 of the present invention. [Figure 4] FIG. 1 is an XRD diagram of a positive electrode material for a sodium ion battery produced in Reference Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, the embodiments of the present invention will be described in detail, and examples of the embodiments are shown in the drawings, and the same or similar reference numerals indicate the same or similar parts or parts having the same or similar functions throughout. The embodiments described below with reference to the drawings are illustrative and are intended to interpret the present invention, but should not be understood as limiting the present invention.

[0019] The following disclosure provides many different embodiments or examples for realizing different structures of the present invention. To simplify the disclosure of the present invention, specific example components and arrangements are described below. It should be understood that these are merely exemplary and are not intended to limit the present invention. Furthermore, the present invention may use repeated reference numerals and / or alphabetical references in different examples. Such repetition is for the purposes of brevity and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. Furthermore, while the present invention provides examples of various specific processes and materials, those skilled in the art will recognize the applicability of other processes and / or the use of other materials.

[0020] The present invention aims to provide a positive electrode material for sodium ion batteries, its manufacturing method, and applications. The present invention uses a low-nickel layered oxide and controls the composition and particle morphology of the transition metal elements iron and manganese to maintain a high capacity of the positive electrode material while maintaining low nickel content, and reduces free sodium ions on the surface, resulting in a positive electrode material for sodium ion batteries with high capacity, low residual alkalinity, and high stability. Furthermore, the manufacturing method is simple and suitable for large-scale industrial production.

[0021] The positive electrode material for a sodium ion battery according to the first embodiment of the present invention has the general chemical formula Na m Ni x Fe y Mn z O2, where 0.1≦x≦0.25, 0.5≦y≦0.8, 0.1≦z≦0.25, 0.8≦m≦1.1, 0.95≦x / z≦1.05, and x+y+z=1, where m, x, y, and z are the mole percentages of the corresponding elements, and each component in the general chemical formula satisfies conservation of charge and conservation of stoichiometry. In the structure of the sodium-ion battery positive electrode material described in the present invention, an ion at the transition metal site forms an octahedral structure with six adjacent oxygen ions, forming an O3-type low-nickel layered oxide material sodium-ion battery positive electrode material with a space group of R-3m.

[0022] Furthermore, the positive electrode material for sodium ion batteries contains a doping element A and has the general chemical formula Na m Ni x Fe y Mn z A p O2, where 0.001≦p≦0.05, 0.1≦x≦0.25, 0.5≦y≦0.8, 0.1≦z≦0.25, 0.8≦m≦1.1, 0.95≦x / z≦1.05, x+y+z=1, m, x, y, z, and p are the mole percentages of the corresponding elements, and each component in the general chemical formula satisfies the conservation of charge and stoichiometry. Element A is lithium (Li + ), magnesium (Mg 2+ ), calcium (Ca 2+ ), copper (Cu 2+), zinc (Zn 2+ ), aluminum (Al 3+ ), boron (B 3+ ), cobalt (Co 3+ ), vanadium (V 3+ ), yttrium (Y 3+ ), Titanium (Ti 4+ ), zirconium (Zr 4+ ), tin (Sn 4+ ), molybdenum (Mo 4+ , Mo 5+ , Mo 6+ ), silicon (Si 4+ ), ruthenium (Ru 4+ ), niobium (Nb 5+ ), antimony (Sb 5 ), tungsten (W 6+ ) may be one or more of the following.

[0023] As shown in FIG. 1, a method for producing a positive electrode material for a sodium ion battery according to an embodiment of the second aspect of the present invention includes the following steps S1 to S3.

[0024] In step S1, a precursor containing a nickel source, an iron source, and a manganese source with a desired stoichiometry is produced by a coprecipitation method. The iron source may be one or more of ferrous sulfate, hydrous ferrous sulfate, ferrous nitrate, and ferrous chloride; the manganese source may be one or more of manganous sulfate, manganous nitrate, manganous chloride, and manganous acetate; and the nickel source may be one or more of nickel chloride, nickel oxide, nickel nitrate, nickel sulfate, and nickel sulfamate.

[0025] Specifically, in the first embodiment of the present invention, as shown in FIG. 2, step S1 includes the following steps S11 to S14.

[0026] In step S11, a nickel source, an iron source, and a manganese source are prepared in an aqueous solution in a stoichiometric ratio. The molar ratio of the nickel source, iron source, and manganese source added satisfies n(Ni):n(Fe):n(Mn)=x:y:z.

[0027] In step S12, an aqueous ammonia solution of a certain concentration and a sodium hydroxide solution of a certain concentration are prepared. The concentration of the aqueous ammonia solution is 25% and the concentration of the sodium hydroxide solution is 15%.

[0028] In step S13, under conditions of constant rotation speed and temperature, the aqueous solution, the ammonia aqueous solution, and the sodium hydroxide solution are fed into the reaction kettle at constant flow rates, the pH value of the reaction system is controlled to 10 to 10.5, and a coprecipitation reaction is carried out to obtain a reaction product. The rotation speed may be 300 to 500 rpm, and the temperature may be 40 to 80° C. The flow rate of the aqueous solution is 1.0 L / h, the flow rate of the aqueous ammonia solution is 0.8 L / h, and the flow rate of the sodium hydroxide solution is 2.0 L / h.

[0029] In step S14, the reaction product is washed, suction filtered, and dried to obtain precursors of the nickel source, iron source, and manganese source.

[0030] In step S2, the precursors of the nickel source, iron source, and manganese source and the sodium source are mixed in a certain ratio, and then a doping element is added and primary sintering is performed to obtain a doped positive electrode material for a sodium ion battery. The molar ratio of the precursors of the nickel source, iron source, and manganese source to the sodium source is 1:(0.8-1.1), and the sodium source may be one or more of sodium carbonate, sodium bicarbonate, sodium sulfate, sodium chloride, sodium perchlorate, sodium nitrate, sodium phosphate, and sodium hydrogen phosphate. The doping element may be one or more of lithium, magnesium, calcium, copper, zinc, aluminum, boron, cobalt, vanadium, yttrium, titanium, zirconium, tin, molybdenum, silicon, ruthenium, niobium, antimony, and tungsten. The primary sintering process involves heating to 480°C at a heating rate of 3°C / min and maintaining the temperature for 4 hours.

[0031] In step S3, the doped sodium ion battery cathode material and the coating are subjected to secondary sintering to obtain the final sodium ion battery cathode material.

[0032] The coating may be one or more of calcium oxide, cobalt oxyhydroxide, aluminum oxide, sodium molybdate, lanthanum oxide, aluminum metaphosphate, titanium oxide, magnesium oxide, zirconium oxide, sodium titanate, cobalt oxide, aluminum fluoride, chromium oxide, zinc oxide, strontium oxide, copper oxide, and tungsten oxide, and the secondary sintering process involves heating to 850°C at a heating rate of 4°C / min and maintaining the temperature for 10 hours.

[0033] The sodium ion battery positive electrode material produced by the method for producing a sodium ion battery positive electrode material according to the embodiment of the present invention is a low-nickel layered oxide material, in which the iron element in the low-nickel layered oxide has electrochemical activity, which can improve the capacity of the low-nickel layered oxide material, and the oxidation of the divalent nickel on the surface causes the deposition of bulk phase sodium, which reduces the content of liberated sodium ions on the surface of the sodium ion battery positive electrode material and makes the surface more stable. In addition, the production method is simple and suitable for large-scale industrial production.

[0034] The present invention will be described in more detail below with reference to examples. Similarly, the examples are merely for the purpose of further illustrating the present invention and should not be understood as limiting the scope of protection of the present invention. Those skilled in the art will understand that any non-essential improvements and adjustments made based on the above content of the present invention also fall within the scope of protection of the present invention. The following exemplary process parameters are also merely examples within appropriate ranges, i.e., those skilled in the art can select values ​​within appropriate ranges based on the description in this specification, and are not limited to the specific numerical values ​​exemplified below.

[0035] ( reference Example 1) Book referenceRegarding the manufacturing method of the positive electrode material for a sodium ion battery according to the example, reference The chemical formula of the positive electrode material for the sodium-ion battery manufactured in this example is NaNi 0.25 Fe 0.5 Mn 0.25 O2 (in this case x=0.25, y=0.5, z=0.25), Chemical formula NaNi 0.25 Fe 0.5 Mn 0.25 According to O2, the steps are as follows: preparing an aqueous solution of nickel sulfate, manganese sulfate, and ferrous sulfate heptahydrate in a molar ratio of nickel, iron, and manganese of 0.25:0.5:1 / 3; preparing an aqueous ammonia solution with a concentration of 25% and an aqueous sodium hydroxide solution with a concentration of 15% under conditions of a rotation speed of 350 rpm and 50°C; and dissolving the aqueous solution, the aqueous ammonia solution, and the sodium hydroxide solution at flow rates of 1.0 L / h, 0.8 L / h, and 2.0 L / h, respectively. The nickel, iron, and manganese precursors are mixed uniformly with sodium carbonate in a molar ratio of 1:1.1, heated to 480°C at a heating rate of 3°C / min, and kept at this temperature for 4 hours. The mixture is then heated to 850°C at a heating rate of 4°C / min and kept at this temperature for 10 hours. The mixture is then mixed with sodium carbonate in a molar ratio of 1:1.1, and the mixture is then heated to 480°C at a heating rate of 3°C / min, and kept at this temperature for 10 hours. The mixture is then heated to 850°C at a heating rate of 4°C / min, and kept at this temperature for 10 hours. The mixture is then mixed with sodium carbonate in a molar ratio of 1:1.1 ... 0.25 Fe 0.5 Mn 0.25 and obtaining a positive electrode material for an O2 sodium-ion battery.

[0036] reference The SEM image of the positive electrode material for sodium ion batteries prepared according to Example 1 is shown in Figure 3. reference The XRD pattern of the positive electrode material for sodium ion batteries prepared according to Example 1 is shown in FIG.

[0037] ( reference Example 2) Book reference Regarding the manufacturing process of the positive electrode material for sodium ion batteries in Example 2, referenceSee Example 1, where x=0.23, y=0.54, z=0.23, and the chemical formula of the positive electrode material for sodium ion batteries is NaNi 0.23 Fe 0.54 Mn 0.23 The only difference is that it is O2.

[0038] ( reference Example 3) Book reference Regarding the manufacturing process of the positive electrode material for sodium ion batteries in Example 3, reference See Example 1, where x=0.2, y=0.6, z=0.2, and the chemical formula of the positive electrode material for sodium ion batteries is NaNi 0.2 Fe 0.6 Mn 0.2 The only difference is that it is O2.

[0039] ( reference Example 4) Book reference Regarding the manufacturing process of the positive electrode material for sodium ion batteries in Example 4, reference See Example 1, where x=0.18, y=0.64, z=0.18, and the chemical formula of the positive electrode material for sodium ion batteries is NaNi 0.18 Fe 0.64 Mn 0.18 The only difference is that it is O2.

[0040] ( reference Example 5) Book reference Regarding the manufacturing process of the positive electrode material for sodium ion batteries in Example 5, reference See Example 1, where x=0.15, y=0.7, z=0.15, and the chemical formula of the positive electrode material for sodium ion batteries is NaNi 0.15 Fe 0.7 Mn 0.15 The only difference is that it is O2.

[0041] ( reference Example 6) Book reference Regarding the manufacturing process of the positive electrode material for sodium ion batteries in Example 6, referenceSee Example 1, where x=0.1, y=0.8, z=0.1, and the chemical formula of the positive electrode material for sodium ion batteries is NaNi 0.1 Fe 0.8 Mn 0.1 The only difference is that it is O2.

[0042] Example 7 Regarding the manufacturing method of the positive electrode material for a sodium ion battery according to this embodiment, the chemical formula of the positive electrode material for a sodium ion battery manufactured in this embodiment is NaNi 0.2 Fe 0.6 Mn 0.2 Ca 0.003 O2 (in this case x=0.2, y=0.6, z=0.2, p=0.003), Chemical formula NaNi 0.2 Fe 0.6 Mn 0.2 Ca 0.003 According to O2, the steps are as follows: preparing an aqueous solution of nickel sulfate, manganese sulfate, and ferrous sulfate heptahydrate in a molar ratio of nickel, iron, and manganese of 0.25:0.5:1 / 3; preparing a 25% aqueous ammonia solution and a 15% aqueous sodium hydroxide solution at a rotation speed of 350 rpm and 50°C; and introducing the aqueous solution, the aqueous ammonia solution, and the sodium hydroxide solution into a reactor in parallel at flow rates of 1.0 L / h, 0.8 L / h, and 2.0 L / h, respectively, to adjust the pH of the reaction system. The nickel, iron, and manganese precursors are mixed uniformly with sodium carbonate in a molar ratio of 1:1.1, and then the calcium-doped compound is added. The mixture is heated to 480°C at a heating rate of 3°C / min and kept at this temperature for 4 hours. Cobalt oxyhydroxide is then added and the mixture is heated to 850°C at a heating rate of 4°C / min and kept at this temperature for 10 hours. NaNi 0.2 Fe 0.6 Mn 0.2 Ca 0.003 and obtaining a positive electrode material for an O2 sodium-ion battery.

[0043] Example 8 The manufacturing process of the positive electrode material for sodium ion batteries in this Example 8 can be referred to Example 7, where p=0.006, and the chemical formula of the positive electrode material for sodium ion batteries is NaNi 0.2 Fe 0.6 Mn 0.2 Ca 0.006 The only difference is that it is O2.

[0044] Example 9 The manufacturing process of the positive electrode material for sodium ion batteries in this Example 9 can be referred to Example 7, and the doping element is zinc, and the chemical formula of the positive electrode material for sodium ion batteries is NaNi 0.2 Fe 0.6 Mn 0.2 Zn 0.003 The only difference is that it is O2.

[0045] Example 10 The manufacturing process of the positive electrode material for sodium ion batteries in this Example 10 can be referred to Example 7, and the doping element is copper, and the chemical formula of the positive electrode material for sodium ion batteries is NaNi 0.2 Fe 0.6 Mn 0.2 Cu 0.003 The only difference is that it is O2.

[0046] (Comparative Example 1) Regarding the manufacturing method of the positive electrode material for a sodium ion battery according to this embodiment, the chemical formula of the positive electrode material for a sodium ion battery manufactured in this embodiment is NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 (in this case x=1 / 3, y=1 / 3, z=1 / 3), Chemical formula NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3According to O2, nickel oxide, iron oxide, and manganese oxide were mixed in a molar ratio of 1 / 3:1 / 3:1 / 3, and when m=1, weighed sodium carbonate was added. The doping compound was added, and the mixture was heated to 480°C at a heating rate of 3°C / min and kept at that temperature for 5 hours. Then, the mixture was further heated to 870°C at a heating rate of 4°C / min and kept at that temperature for 12 hours. 1 / 3 Fe 1 / 3 Mn 1 / 3 The method includes obtaining a positive electrode material for an O2 sodium-ion battery.

[0047] (Comparative Example 2) Regarding the manufacturing method of the positive electrode material for a sodium ion battery according to this embodiment, the chemical formula of the positive electrode material for a sodium ion battery manufactured in this embodiment is NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 (in this case x=1 / 3, y=1 / 3, z=1 / 3), Chemical formula NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 According to O2, the steps are as follows: preparing an aqueous solution of nickel sulfate, manganese sulfate, and ferrous sulfate heptahydrate in a molar ratio of nickel, iron, and manganese of 1 / 3:1 / 3:1 / 3; preparing an aqueous ammonia solution with a concentration of 25% and a sodium hydroxide solution with a concentration of 15% under conditions of a rotation speed of 350 rpm and 50°C; and discharging the aqueous solution, the aqueous ammonia solution, and the sodium hydroxide solution in parallel at flow rates of 1.0 L / h, 0.8 L / h, and 2.0 L / h, respectively. The pH value of the reaction system is controlled to 10-10.5, and a coprecipitation reaction is carried out. The mixture is then washed, suction filtered, and dried to obtain precursors of nickel, iron, and manganese sources. The precursors of nickel, iron, and manganese sources are uniformly mixed with sodium carbonate in a molar ratio of 1:1.1, and then heated to 480°C at a heating rate of 3°C / min, kept at this temperature for 4 hours, and then heated to 850°C at a heating rate of 4°C / min, kept at this temperature for 10 hours, and then the mixture is mixed to obtain NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 and obtaining a positive electrode material for an O2 sodium-ion battery.

[0048] the above reference Example 1 ~6, Reference example 7 The content of free sodium ions was tested for the positive electrode material for sodium ion batteries manufactured in the methods for manufacturing a positive electrode material for sodium ion batteries according to the embodiments of the present invention. reference Example 1 6. Examples 7- The sodium-ion battery cathode material prepared in Comparative Examples 1 and 2, carbon black (conductive agent), and polyvinylidene fluoride (binder) were dispersed in N-methylpyrrolidone in a mass ratio of 90:5:5. The mixture was uniformly dispersed using a ball mill, then coated on aluminum foil and vacuum dried to prepare a cathode plate. The electrolyte solution was 1 mol / L LiPF6, with a solvent volume ratio of EC:DMC:EMC = 1:1:1. The separator was a Celgard polypropylene film, and a metallic lithium sheet was used as the anode. These were then assembled into a button-type half cell. The test voltage range was 2.5 V to 4.5 V. The battery was charged to 4.5 V using a constant current / constant voltage charging method and discharged to 2.5 V using a constant current / discharging method. The charge / discharge current was 0.1 C, for two cycles. Specific test items and test results are shown in Table 1 below.

[0049] Table 1 reference Example 1 6. Examples 7- Test items and test results for 10 and Comparative Examples 1 and 2 [Table 1]

[0050] The above examples , reference example By comparing the results of the tests and comparative examples, it can be seen that the method for manufacturing a positive electrode material for a sodium ion battery according to the embodiment of the present invention can effectively improve the discharge specific capacity of the positive electrode material for a sodium ion battery, reduce the content of free sodium ions on the surface of the positive electrode material for a sodium ion battery, and improve the stability of the material.

[0051] As described above, the method for manufacturing a positive electrode material for a sodium ion battery according to the embodiment of the present invention uses a low-nickel layered oxide and controls the composition and particle morphology of the transition metal elements iron and manganese, thereby maintaining a high capacity of the positive electrode material while maintaining a low nickel content and reducing free sodium ions on the surface, resulting in a positive electrode material for a sodium ion battery with high capacity, low residual alkalinity, and high stability. Furthermore, the manufacturing method is simple and suitable for large-scale industrial production.

[0052] In the description herein, references to the terms "one embodiment," "some embodiments," "example," "specific example," "some examples," etc., mean that the specific features, structures, materials, or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present invention. In the description herein, the exemplary expressions of the above terms are not necessarily limited to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be appropriately combined in any one or more embodiments or examples. Furthermore, if not mutually inconsistent, a person skilled in the art may combine or combine different embodiments or examples and features of different embodiments or examples described herein.

[0053] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and purpose of the present invention, and that the scope of the present invention is limited by the claims and their equivalents.

Claims

1. A compound containing a doping element A and having the general chemical formula Na ｍ Ni ｘ Fe ｙ Mn ｚ A pO ２ wherein 0.1≦x≦0.25, 0.5≦y≦0.8, 0.1≦z≦0.25, 0.8≦m≦1.1, 0.95≦x / z≦1.05, x+y+z=1, 0.001≦p≦0.05, m, x, y, z, and p are the mole percentages of the corresponding elements, and each component in the general chemical formula satisfies the conservation of charge and the conservation of stoichiometry; The doping element A is one or more of the elements lithium, magnesium, calcium, copper, zinc, aluminum, boron, cobalt, vanadium, yttrium, titanium, zirconium, tin, molybdenum, ruthenium, niobium, antimony, and tungsten.

2. A method for producing the positive electrode material for a sodium ion battery according to claim 1, Step S1: preparing a precursor containing a nickel source, an iron source, and a manganese source with a desired stoichiometry by a coprecipitation method; Step S2: mixing the precursors of the nickel source, the iron source, and the manganese source with the sodium source in a certain ratio, adding a doping element, and performing primary sintering to obtain a doped positive electrode material for a sodium ion battery; and step S3 of secondary sintering the doped sodium ion battery cathode material and the coating to obtain a final sodium ion battery cathode material. A manufacturing method characterized by:

3. In step S1, the iron source is one or more of ferrous sulfate, hydrous ferrous sulfate, ferrous nitrate, and ferrous chloride, the manganese source is one or more of manganese sulfate, manganese nitrate, manganese chloride, and manganese acetate, and the nickel source is one or more of nickel chloride, nickel oxide, nickel nitrate, nickel sulfate, and nickel sulfamate. The method for producing a positive electrode material for a sodium ion battery according to claim 2 .

4. The step S1 Step S11: preparing an aqueous solution containing the nickel source, the iron source, and the manganese source in a stoichiometric ratio; Step S12: preparing a fixed concentration aqueous ammonia solution and a fixed concentration sodium hydroxide solution; Step S13: feeding the aqueous solution, the aqueous ammonia solution, and the sodium hydroxide solution into the reactor at a constant flow rate under conditions of a constant rotation speed and temperature, controlling the pH value of the reaction system to 10 to 10.5, and carrying out a coprecipitation reaction to obtain a reaction product; and step S14 of washing the reaction product, suction filtering, and drying to obtain precursors of the nickel source, iron source, and manganese source. The method for producing a positive electrode material for a sodium ion battery according to claim 2 .

5. the molar ratios of the nickel source, the iron source, and the manganese source added satisfy n(Ni):n(Fe):n(Mn)=x:y:z, the concentration of the aqueous ammonia solution is 25%, the concentration of the sodium hydroxide solution is 15%, the rotation speed is 300 to 500 rpm, the temperature is 40 to 80°C, the flow rates of the aqueous solution are 1.0 L / h, the flow rate of the aqueous ammonia solution is 0.8 L / h, and the flow rate of the sodium hydroxide solution is 2.0 L / h; The method for producing a positive electrode material for a sodium ion battery according to claim 4 .

6. In step S2, the molar ratio of the precursors of the nickel source, the iron source, and the manganese source to the sodium source is 1:(0.8 to 1.1), and the sodium source is one or more of sodium carbonate, sodium hydrogencarbonate, sodium sulfate, sodium chloride, sodium perchlorate, sodium nitrate, sodium phosphate, and sodium hydrogen phosphate. The method for producing a positive electrode material for a sodium ion battery according to claim 2 .

7. In step S2, the doping element may be one or more of lithium, magnesium, calcium, copper, zinc, aluminum, boron, cobalt, vanadium, yttrium, titanium, zirconium, tin, molybdenum, ruthenium, niobium, antimony, and tungsten, and the primary sintering process is to heat the material to 480°C at a heating rate of 3°C / min and keep the temperature for 4 hours. The method for producing a positive electrode material for a sodium ion battery according to claim 2 .

8. In step S3, the coating material is one or more of calcium oxide, cobalt oxyhydroxide, aluminum oxide, sodium molybdate, lanthanum oxide, aluminum metaphosphate, titanium oxide, magnesium oxide, zirconium oxide, sodium titanate, cobalt oxide, aluminum fluoride, chromium oxide, zinc oxide, strontium oxide, copper oxide, and tungsten oxide, and the secondary sintering process is heating to 850°C at a heating rate of 4°C / min and maintaining the temperature for 10 hours. The method for producing a positive electrode material for a sodium ion battery according to claim 2 .

9. A sodium ion battery comprising the positive electrode material for sodium ion batteries according to claim 1.

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