Sodium ion battery cathode material, and preparation method therefor and application thereof

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 for producing lithium-ion batteries are far from meeting the explosively increasing demand. Sodium-ion batteries have the characteristics of similar energy storage mechanism and abundant storage capacity as lithium-ion batteries, and therefore they will become a strong competitor to replace lithium-ion batteries in large-scale energy storage systems.

[0003] The layered sodium ion battery is regarded as 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, Mn are transition metal elements, M is an element that dopes and substitutes the transition metal site, and in the structure of the oxide material, the ions at the transition metal site form an octahedral structure with six adjacent oxygens, and are arranged alternately with the NaO6 layers of octahedral coordination, constituting an O3-type sodium ion battery high nickel layered oxide material with space group R-3m, and M is specifically 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 charge conservation and stoichiometry conservation, and 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 positive electrode materials for sodium ion batteries, have problems such as high cost, high residual alkali 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, and a manufacturing method and application thereof. In the present invention, by controlling the composition and particle morphology of the transition metal elements iron and manganese, the positive electrode material maintains high capacity while maintaining low nickel, and reduces free sodium ions on the surface, thereby obtaining a low-nickel sodium ion battery positive electrode material with high capacity, low residual alkali, and high stability. In addition, the manufacturing method is simple and suitable for application in 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, and 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 the 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 charge conservation and stoichiometric conservation, and 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 a sodium ion battery cathode material according to the above 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 a sodium source in a certain ratio, and then adding a doping element to perform primary sintering to obtain a doped sodium ion battery cathode material; and secondary sintering 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, ferrous chloride, the manganese source is one or more of manganous sulfate, manganous nitrate, manganous chloride, and manganous 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 ammonia aqueous solution of a constant concentration and a sodium hydroxide solution of a constant concentration; feeding the aqueous solution, the ammonia aqueous solution, and the sodium hydroxide solution into a reaction kettle at a constant flow rate, controlling the pH value of the reaction system to 10 to 10.5, performing a coprecipitation reaction, and obtaining a reaction product; and washing, suction filtering, and drying the reaction product to obtain 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 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 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.

[0012] Preferably, 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 hydrogen carbonate, sodium sulfate, sodium chloride, sodium perchlorate, sodium nitrate, sodium phosphate, and sodium hydrogen phosphate.

[0013] Preferably, the doping element can 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 elements, and the primary sintering process is to heat to 480°C at a heating rate of 3°C / min and keep at 4h.

[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 cathode material according to the first aspect. Effect of the Invention

[0016] In the positive electrode material for sodium ion batteries according to the embodiment of the present invention, its manufacturing method and application use low nickel layered oxide, and control the composition and particle morphology of transition metal elements iron and manganese, thereby maintaining high capacity of the positive electrode material while maintaining low nickel, reducing free sodium ions on the surface, and obtaining a positive electrode material for sodium ion batteries with high capacity, low residual alkali and high stability. In addition, the manufacturing method has a simple process and is suitable for application in large-scale industrial production. [Brief description of the drawings]

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

[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 throughout indicate the same or similar parts or parts having the same or similar functions. The embodiments described below with reference to the drawings are illustrative and are for interpreting 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. In order to simplify the disclosure of the present invention, the following describes specific example components and configurations. It should be understood that these are merely exemplary and are not intended to limit the present invention. The present invention may also use repeated reference numerals and / or alphabetical references in different examples. Such repetition is for the purpose of brevity and clarity and does not in itself indicate a relationship between the various embodiments and / or configurations discussed. In addition, while the present invention provides examples of various specific processes and materials, one skilled in the art may 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 application, in which a low-nickel layered oxide is used, and the composition and particle morphology of the transition metal elements iron and manganese are controlled to maintain a high capacity of the positive electrode material while maintaining low nickel, and to reduce free sodium ions on the surface, thereby obtaining a positive electrode material for sodium ion batteries with high capacity, low residual alkali and high stability. In addition, 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, x+y+z=1, m, x, y, z 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. In the structure of the sodium ion battery positive electrode material described in the present invention, the ion at the transition metal site forms an octahedral structure with six adjacent oxygen ions, constituting an O3 type low nickel layered oxide material sodium ion battery positive electrode material with space group 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 the conservation of 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 above.

[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, the 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, the iron source, and the manganese source added satisfies n(Ni):n(Fe):n(Mn)=x:y:z.

[0027] In step S12, an aqueous ammonia solution having a certain concentration and a sodium hydroxide solution having 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, the aqueous solution, the aqueous ammonia solution, and the sodium hydroxide solution are fed into the reaction kettle at constant flow rates under conditions of constant rotation speed and temperature, 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 300-500 rpm and the temperature may be 40-80° 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, the iron source, the manganese source and the sodium source are mixed in a certain ratio, and then the 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 hydrogen carbonate, 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 is to heat to 480°C at a heating rate of 3°C / min and keep the temperature for 4 hours.

[0031] In step S3, the doped sodium ion battery positive electrode material and the coating are secondarily sintered to obtain a final sodium ion battery positive electrode 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 is to heat up to 850°C at a heating rate of 4°C / min and keep the temperature for 10 hours.

[0033] The sodium ion battery positive electrode material produced by the method for producing the sodium ion battery positive electrode material according to the embodiment of the present invention is a low nickel layered oxide material, 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 bulk phase sodium to precipitate, so that the content of the sodium ion liberated from the surface of the sodium ion battery positive electrode material is lower and the surface is more stable. In addition, the production method has a simple process and is suitable for application in 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 should understand that some 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 one example within an appropriate range, that is, those skilled in the art can select within an appropriate range according to the description in this specification, and are not limited to the specific numerical values ​​exemplified below.

[0035] Example 1 Regarding the manufacturing method of the positive electrode material for sodium ion batteries according to this embodiment, the chemical formula of the positive electrode material for sodium ion batteries manufactured in this embodiment 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: 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 solution of ammonia 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 feeding the aqueous solution, the aqueous solution of ammonia, 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 source precursors are mixed with sodium carbonate at a molar ratio of 1:1.1, heated to 480°C at a heating rate of 3°C / min and kept at 850°C for 10 hours, and then heated to 850°C at a heating rate of 4°C / min and kept at 850°C for 10 hours to obtain NaNi 0.25 Fe 0.5 Mn 0.25 and obtaining a positive electrode material for O2 sodium ion batteries.

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

[0037] Example 2 The manufacturing process of the sodium ion battery positive electrode material in this Example 2 can be referred to Example 1, where x=0.23, y=0.54, z=0.23, and the chemical formula of the sodium ion battery positive electrode material is NaNi 0.23 Fe 0.54 Mn0.23 The only difference is that it is O2.

[0038] Example 3 The manufacturing process of the sodium ion battery positive electrode material in this Example 3 can be referred to Example 1, where x=0.2, y=0.6, z=0.2, and the chemical formula of the sodium ion battery positive electrode material is NaNi 0.2 Fe 0.6 Mn 0.2 The only difference is that it is O2.

[0039] Example 4 The manufacturing process of the sodium ion battery positive electrode material in this Example 4 can be referred to Example 1, where x=0.18, y=0.64, z=0.18, and the chemical formula of the sodium ion battery positive electrode material is NaNi 0.18 Fe 0.64 Mn 0.18 The only difference is that it is O2.

[0040] Example 5 The manufacturing process of the sodium ion battery positive electrode material in this Example 5 can be referred to Example 1, where x=0.15, y=0.7, z=0.15, and the chemical formula of the sodium ion battery positive electrode material is NaNi 0.15 Fe 0.7 Mn 0.15 The only difference is that it is O2.

[0041] Example 6 The manufacturing process of the sodium ion battery positive electrode material in this Example 6 can refer to Example 1, where x=0.1, y=0.8, z=0.1, and the chemical formula of the sodium ion battery positive electrode material 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 sodium ion batteries according to this embodiment, the chemical formula of the positive electrode material for sodium ion batteries manufactured in this embodiment is NaNi0.2 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: 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 solution of ammonia 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 feeding the aqueous solution, the aqueous solution of ammonia, and the sodium hydroxide solution into a reactor 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 source, iron source, and manganese source precursors are mixed uniformly with sodium carbonate in a molar ratio of 1:1.1, and then a calcium-doped compound is added. The mixture is heated to 480°C at a heating rate of 3°C / min and kept at 4 hours. Cobalt oxyhydroxide coating is then added, heated to 850°C at a heating rate of 4°C / min and kept at 4 hours. NaNi 0.2 Fe 0.6 Mn 0.2 Ca 0.003 and obtaining a positive electrode material for O2 sodium ion batteries.

[0043] Example 8 The manufacturing process of the sodium ion battery positive electrode material in this Example 8 can be referred to Example 7, and p=0.006. The chemical formula of the sodium ion battery positive electrode material 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 sodium ion battery positive electrode material in this Example 9 can be referred to Example 7, the doping element is zinc, and the chemical formula of the sodium ion battery positive electrode material is NaNi 0.2 Fe 0.6 Mn 0.2 Zinc 0.003 The only difference is that it is O2.

[0045] Example 10 The manufacturing process of the sodium ion battery positive electrode material in this Example 10 can refer to Example 7, the doping element is copper, and the chemical formula of the sodium ion battery positive electrode material 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 sodium ion batteries according to this embodiment, the chemical formula of the positive electrode material for sodium ion batteries 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, nickel oxide, iron oxide, and manganese oxide are mixed in a molar ratio of nickel, iron, and manganese of 1 / 3:1 / 3:1 / 3. When m=1, weighed sodium carbonate is added, and the doping compound is added. The mixture is heated to 480°C at a heating rate of 3°C / min and kept at that temperature for 5 hours. The mixture is then heated to 870°C at a heating rate of 4°C / min and kept at that temperature for 12 hours. The NaNi 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 sodium ion batteries according to this embodiment, the chemical formula of the positive electrode material for sodium ion batteries manufactured in this embodiment is NaNi 1 / 3Fe 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 solution of ammonia 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 feeding the aqueous solution, the aqueous solution of ammonia, 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 nickel, iron and manganese source precursors are mixed with sodium carbonate at a molar ratio of 1:1.1, heated to 480°C at a heating rate of 3°C / min and kept at 850°C for 10 hours, and then heated to 850°C at a heating rate of 4°C / min and kept at 850°C for 10 hours to obtain NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 and obtaining a positive electrode material for O2 sodium ion batteries.

[0048] In order to test the free sodium ion content of the sodium ion battery positive electrode material manufactured in the above Examples 1 to 10 and the sodium ion battery positive electrode material manufactured in the above Comparative Examples 1 to 2, and to verify the mass of the finished product of the sodium ion battery positive electrode material manufactured by the manufacturing method of the sodium ion battery positive electrode material according to the embodiment of the present invention, the sodium ion battery positive electrode material manufactured in the above Examples 1 to 10 and Comparative Examples 1 to 2, the conductive agent carbon black, and the binder polyvinylidene fluoride were dispersed in N-methylpyrrolidone at a mass ratio of 90:5:5, uniformly dispersed in a ball mill, and then coated on aluminum foil and dried in vacuum to manufacture a positive electrode plate. The electrolyte with a solvent volume ratio of EC:DMC:EMC=1:1:1 was 1mol / L LiPF6, the separator was a Celgard polypropylene film, and the metal lithium sheet was the negative electrode, and they were assembled into a button-type half cell. The test voltage range was 2.5 V to 4.5 V, and 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, with two cycles at a charge / discharge current of 0.1 C. The specific test items and test results are shown in Table 1 below.

[0049] Table 1. Test items and test results for Examples 1 to 10 and Comparative Examples 1 and 2 [Table 1]

[0050] Comparing the above Examples and Comparative Examples and the test results obtained by testing them, it can be seen that the manufacturing method of the positive electrode material for sodium ion batteries according to the embodiments of the present invention can effectively improve the discharge specific capacity of the positive electrode material for sodium ion batteries, reduce the content of free sodium ions on the surface of the positive electrode material for sodium ion batteries, and improve the stability of the material.

[0051] In view of the above, the method for producing a positive electrode material for sodium ion batteries according to the embodiment of the present invention uses 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 low nickel, reducing the free sodium ions on the surface, and obtaining a positive electrode material for sodium ion batteries with high capacity, low residual alkali, and high stability. In addition, the method for producing the same is simple and suitable for large-scale industrial production.

[0052] In the description of this specification, a description referring to the terms "one embodiment", "several embodiments", "examples", "specific examples", "several examples", etc. means that the specific features, structures, materials or characteristics described in the combination of the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the exemplary expressions of the above terms are not necessarily limited to the same embodiment or example. And, the specific features, structures, materials or characteristics described can be appropriately combined in any one or more embodiments or examples. In addition, if not mutually inconsistent, a person skilled in the art can combine or combine different embodiments or examples described in this specification and features of different embodiments or examples.

[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 objectives of the present invention, and that the scope of the present invention is limited by the claims and their equivalents.

Claims

1. The general chemical formula is Na ｍ Ni ｘ Fe ｙ Mn ｚ O ２ 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 the conservation of stoichiometry; A positive electrode material for a sodium ion battery.

2. 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 O ２ Wherein, 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 mole percentages of the corresponding elements, and each component in the general chemical formula satisfies charge conservation and stoichiometric conservation. 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; The positive electrode material for a sodium ion battery according to claim 1 .

3. A method for producing the positive electrode material for a sodium ion battery according to claim 1, Step S1 of producing a precursor containing a nickel source, an iron source, and a manganese source of 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 sodium ion battery positive electrode material; 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 comprising the steps of:

4. In the 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 3 .

5. The step S1 is Step S11 of preparing an aqueous solution of the nickel source, the iron source, and the manganese source in a stoichiometric ratio; Step S12 of preparing ammonia solution of a certain concentration and sodium hydroxide solution of a certain concentration; Step S13: feeding the aqueous solution, the aqueous ammonia solution, and the sodium hydroxide solution into the reactor at a constant flow rate under the 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, suction filtering, and drying the reaction product to obtain precursors of the nickel source, the iron source, and the manganese source. The method for producing a positive electrode material for a sodium ion battery according to claim 3 .

6. 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 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; The method for producing a positive electrode material for a sodium ion battery according to claim 5 .

7. In the 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 hydrogen carbonate, 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 3 .

8. 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, silicon, ruthenium, niobium, antimony, and tungsten elements, and the primary sintering process is to heat to 480°C at a heating rate of 3°C / min and keep the temperature for 4h; The method for producing a positive electrode material for a sodium ion battery according to claim 3 .

9. 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 keeping the temperature for 10 hours. The method for producing a positive electrode material for a sodium ion battery according to claim 3 .

10. A sodium ion battery comprising the positive electrode material for sodium ion batteries according to any one of claims 1 to 2.

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