Preparation method and application of low-cost self-doped sodium-ion battery positive electrode material

Abstract

The application discloses a preparation method and application of a low-cost self-doped sodium-ion battery positive electrode material, and comprises the following steps: copper ore, iron ore and nickel ore are sequentially subjected to first calcination treatment, crushing treatment and magnetic separation treatment to obtain a high-magnetic-substance copper-containing mixture, an iron-containing mixture and a nickel-containing mixture; the copper-containing mixture, the iron-containing mixture and the nickel-containing mixture are weighed according to stoichiometric ratios of a manganese-containing compound and a sodium-containing compound, mixed in a solvent, uniformly mixed and dried to obtain a mixed powder; and the mixed powder is subjected to second calcination treatment to obtain the positive electrode material. The preparation method greatly reduces a raw material purification and impurity removal process, utilizes rare elements contained in minerals, prepares a self-doped layered oxide material, has simple preparation process and low cost, and the prepared positive electrode material has high capacity performance, high rate performance and cycle performance.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and specifically to a method for preparing and applying a sodium-ion battery cathode material, particularly a method for preparing and applying a low-cost self-doped sodium-ion battery cathode material. Background Technology

[0002] Sodium-ion batteries, with their advantages of abundant and widely distributed sodium resources and low cost, have overcome the limitations of lithium-ion batteries, which suffer from scarce resources, uneven distribution, and high cost, and have attracted widespread attention. The positive electrode material of sodium-ion batteries primarily serves as a sodium-rich substrate, ensuring sufficient sodium ions are transported in the electrolyte during charging. Currently, researchers are focusing on sodium-ion battery positive electrode materials including layered transition metal oxides, Prussian blue compounds, and polyanionic compounds. Among these, layered sodium oxides have been extensively studied due to their relative ease of synthesis, adjustable voltage range, and high specific capacity.

[0003] Currently, the preparation processes of sodium-ion layered oxides and lithium-ion ternary cathode materials are quite similar. Furthermore, the preparation of these cathode materials typically requires high-purity raw materials, which increases the processing cost of the battery. Therefore, further reducing the processing cost of sodium-ion cathode materials while ensuring their performance is crucial for enhancing the cost advantage of sodium-ion batteries. Summary of the Invention

[0004] This invention provides a low-cost method for preparing and applying a self-doped sodium-ion battery cathode material. The method involves directly preparing a self-doped layered oxide material by solid-state sintering after simple calcination, crushing, and magnetic separation of the original mineral material. This type of self-doped layered oxide material can be used as a cathode material for sodium-ion batteries, enabling sodium-ion batteries containing this cathode material to exhibit high rate performance and cycle performance while ensuring capacity.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] The first aspect of this invention provides a method for preparing a sodium-ion battery cathode material, comprising the following steps:

[0007] (1) The copper ore, iron ore and nickel ore are calcined for the first time, and then crushed to obtain the corresponding copper mixture particles, iron mixture particles and nickel mixture particles.

[0008] (2) The copper mixture particles, iron mixture particles and nickel mixture particles mentioned above are subjected to magnetic separation to obtain copper-containing mixture, iron-containing mixture and nickel-containing mixture;

[0009] (3) Weigh the above copper-containing mixture, iron-containing mixture, nickel-containing mixture, manganese-containing compound, and sodium-containing compound according to the stoichiometric ratio of the metal elements sodium, nickel, iron, copper, and manganese in the cathode material, mix them in a solvent, and dry them after uniform mixing to obtain precursor powder.

[0010] (4) The above precursor powder is subjected to a second calcination treatment to obtain the cathode material;

[0011] The positive electrode material is Na. x [Ni a Fe b Mn c Cu d M' e O2, wherein M' contains one or more of Zn, Mo, Co, Cr, Al, and Ti, 0.6≤x≤1.2, 0<a≤0.4, 0<b≤0.4, 0<c≤0.4, 0<e≤0.1, and a+b+c+d+e=1.

[0012] Further, in step (1), the copper ore is selected from one or more of chalcocite, cuprite, chalcopyrite, azurite, malachite, and chalcopyrite, more preferably chalcocite.

[0013] Further, in step (1), the iron ore is selected from one or more of hematite, specularite, magnetite, maghemite, ilmenite, limonite, and siderite, and is more preferably hematite.

[0014] Further, in step (1), the nickel ore is selected from one or more of goethite, chalcopyrite, and pyrite, more preferably chalcopyrite.

[0015] Further, in step (1), the calcination temperature for the first calcination treatment of the copper ore is preferably 600-1500℃, such as 600℃, 700℃, 800℃, 900℃, 1000℃, 1100℃, 1200℃, 1300℃, 1400℃, 1500℃, etc., and the calcination time is preferably 2-15h, such as 15h, 14h, 13h, 12h, 11h, 10h, 9h, 8h, 7h, 6h, 5h, 4h, 3h, 2h, etc., including but not limited to the temperatures or times listed above.

[0016] Further, in step (1), the calcination temperature for the first calcination treatment of the iron ore is preferably 300-900℃, such as 300℃, 400℃, 500℃, 600℃, 700℃, 800℃, 900℃, etc., and the calcination time is preferably 2-15h, such as 15h, 14h, 13h, 12h, 11h, 10h, 9h, 8h, 7h, 6h, 5h, 4h, 3h, 2h, etc., including but not limited to the temperatures or times listed above.

[0017] Further, in step (1), the calcination temperature for the first calcination treatment of the nickel ore is preferably 500-1300℃, such as 500℃, 600℃, 700℃, 800℃, 900℃, 1000℃, 1100℃, 1200℃, 1300℃, etc., and the calcination time is preferably 15h, 14h, 13h, 12h, 11h, 10h, 9h, 8h, 7h, 6h, 5h, 4h, 3h, 2h, etc., including but not limited to the temperatures or times listed above.

[0018] Further, in step (1), the median particle size D50 of the copper mixture particles, iron mixture particles, and nickel mixture particles is preferably 0.5-30 μm, for example, D50 is 0.5-1.0 μm, 1-1.5 μm, 1.5-2.0 μm, 2-2.5 μm, 2.5-3.0 μm, 3.0-3.5 μm, 3.5-4.0 μm, 4.0-4.5 μm, 4.5-5.0 μm, 5.0-5.5 μm, 5.5-6.0 μm, 6.0-6.5 μm, 6 Values ​​within the ranges of 0.5-7.0μm, 7.0-7.5μm, 7.5-8.0μm, 8.0-8.5μm, 8.5-9.0μm, 9.0-9.5μm, 9.5-10.0μm, 10.0-11μm, 11-12.0μm, 12.0-15.0μm, 15.0-18.0μm, 18.0-20.0μm, 20.0-23.0μm, 23.0-25.0μm, 25.0-28.0μm, and 28.0-30.0μm.

[0019] Further, in step (2), the mass percentage of the copper-containing mixture in the copper mixture particles is not less than 75%, the mass percentage of copper element in the copper-containing mixture is 60-79%, more preferably 71-79%, and the copper-containing mixture contains one or two of CuO and CuS.

[0020] Further, in step (2), the iron-containing mixture accounts for no less than 75% of the mass of the iron mixture particles, the mass percentage of iron element in the iron-containing mixture is 52.5-69.3%, more preferably 63-69%, and the iron-containing mixture contains one or more of FeO, Fe2O3, and Fe3O4.

[0021] Further, in step (2), the nickel-containing mixture accounts for no less than 75% of the mass of the nickel mixture particles, the nickel element in the nickel-containing mixture accounts for 58.9-77.8% of the mass, more preferably 70-77 wt%, and the nickel-containing mixture contains one or more of NiO, Ni2O3, and Ni3O4.

[0022] Further, in step (3), the manganese-containing compound is selected from one or more of potassium permanganate, potassium manganate, and manganese oxide.

[0023] Further, in step (3), the sodium-containing compound is selected from one or more of sodium carbonate, sodium hydroxide, sodium oxide, sodium peroxide, sodium phosphate, sodium sulfate, sodium dihydrogen phosphate, sodium dihydrogen sulfate, and sodium phenolate.

[0024] Further, in step (3), the solvent is ethanol and / or N-methylpyrrolidone; the drying temperature is 80-110℃, such as 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, etc., and the drying time is 5-15h, such as 5h, 6h, 7h, 8h, 9h, 12h, 14h, 15h, etc., including but not limited to the temperatures or times listed above.

[0025] Further, in step (4), the temperature of the second calcination treatment is preferably 700-1100℃, such as 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃, etc., and the calcination time is preferably 8-20h, such as 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, etc., including but not limited to the temperatures or times listed above.

[0026] A second aspect of the present invention provides a cathode material, which is prepared by the preparation method described in the first aspect.

[0027] A third aspect of the present invention provides a positive electrode sheet comprising the positive electrode material described in the second aspect.

[0028] A fourth aspect of the present invention provides a sodium-ion battery comprising the positive electrode material described in the second aspect, or the positive electrode sheet described in the third aspect.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] 1. This invention provides a low-cost method for preparing self-doped sodium-ion battery cathode materials. The method involves simple calcination, crushing, and magnetic separation of raw iron, manganese, and copper mineral materials to obtain a highly magnetic mixture. Since the raw mineral materials contain small amounts of other transition elements or other metallic elements, the self-doped layered oxide material can be prepared by solid-state sintering of the aforementioned simply treated highly magnetic mixture with other metal compounds (containing manganese and sodium compounds). This preparation method is simple and does not require the use of high-purity raw materials; it can directly use the simply treated mineral materials as raw materials, effectively reducing the preparation cost of the cathode material.

[0031] 2. The self-doped layered oxide material prepared by the above method can be used as a cathode material for sodium-ion batteries. Compared with cathode materials prepared using precursor salts in the prior art and commercially available layered oxides, sodium-ion batteries containing cathode materials prepared by the method described in this invention have comparable capacity and exhibit better rate performance and cycle stability. Attached Figure Description

[0032] Figure 1 The image shows the XRD pattern of the cathode material prepared in Example 1. Detailed Implementation

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. "Comprising" or "containing" as used herein means that it may include or contain other components in addition to the stated components. "Comprising" or "containing" as used herein may also be replaced with the closed form "is" or "consisting of".

[0034] As described in the background section, sodium-ion layered oxides are usually obtained by processing high-purity raw material metal salts. The processing and purification of raw materials increases the processing cost of batteries. How to further reduce the processing cost of sodium-ion cathode materials while ensuring their performance is one of the urgent problems to be solved to further improve the cost advantage of sodium-ion batteries.

[0035] To address the aforementioned technical problems, embodiments of the present invention provide a method for preparing a sodium-ion battery cathode material, comprising the following steps:

[0036] (1) The copper ore, iron ore and nickel ore are calcined for the first time, and then crushed to obtain the corresponding copper mixture particles, iron mixture particles and nickel mixture particles.

[0037] (2) The copper mixture particles, iron mixture particles and nickel mixture particles mentioned above are subjected to magnetic separation to obtain copper-containing mixture, iron-containing mixture and nickel-containing mixture;

[0038] (3) Weigh the above copper-containing mixture, iron-containing mixture, nickel-containing mixture, manganese-containing compound, and sodium-containing compound according to the stoichiometric ratio of the metal elements sodium, nickel, iron, copper, and manganese in the cathode material, mix them in a solvent, and dry them after uniform mixing to obtain precursor powder.

[0039] (4) The above precursor powder is subjected to a second calcination treatment to obtain the cathode material;

[0040] The above-mentioned cathode material is Na x [Ni a Fe b Mn c Cu d M' e O2, wherein M' contains one or more of Zn, Mo, Co, Cr, Al, Ti, and Ca, 0.6≤x≤1.2, 0<a≤0.4, 0<b≤0.4, 0<c≤0.4, 0<e≤0.1, and a+b+c+d+e=1.

[0041] This invention is based on the differences in element types between sodium-ion battery layered oxide cathode materials and lithium-ion ternary cathode materials. It directly uses raw mineral materials such as copper ore, iron ore, and nickel ore as raw materials and obtains a highly magnetic mixture through simple pretreatment (calcination, crushing, and magnetic separation). This highly magnetic mixture contains a small amount of other transition metal elements or other metal elements, such as one or more of Zn, Mo, Co, Cr, Al, and Ti. Thus, self-doped layered oxide materials can be prepared by solid-state sintering of this highly magnetic mixture with manganese-containing compounds and sodium-containing compounds.

[0042] In some preferred embodiments, in step (1), the copper ore may be selected from one or more of chalcocite, cuprite, chalcopyrite, azurite, malachite, and tetrahedrite, more preferably chalcocite; the iron ore may be selected from one or more of hematite, specularite, magnetite, maghemite, ilmenite, limonite, and siderite, more preferably hematite; and the nickel ore may be selected from one or more of goethite, chalcopyrite, and pyrrhotite, more preferably chalcopyrite.

[0043] In some preferred embodiments, in step (1), the calcination temperature for the first calcination treatment of the copper ore is 600-1500℃, such as 600℃, 700℃, 800℃, 900℃, 1000℃, 1100℃, 1200℃, 1300℃, 1400℃, 1500℃, etc., including but not limited to the temperature values ​​listed above; more specifically, the copper ore is calcined at the above temperature for 2-15 hours, such as 15 hours, 14 hours, 13 hours, 12 hours, 11 hours, 10 hours, 9 hours, 8 hours, 7 hours, 6 hours, 5 hours, 4 hours, 3 hours, 2 hours, etc., including but not limited to the time listed above.

[0044] In some preferred embodiments, in step (1), the calcination temperature for the first calcination treatment of the iron ore is 300-900℃, such as 300℃, 400℃, 500℃, 600℃, 700℃, 800℃, 900℃, etc., including but not limited to the temperature values ​​listed above; more specifically, the iron ore is calcined at the above temperature for 2-15 hours, such as 15 hours, 14 hours, 13 hours, 12 hours, 11 hours, 10 hours, 9 hours, 8 hours, 7 hours, 6 hours, 5 hours, 4 hours, 3 hours, 2 hours, etc., including but not limited to the times listed above.

[0045] In some preferred embodiments, in step (1), the calcination temperature for the first calcination treatment of nickel ore is 500-1300℃, such as 500℃, 600℃, 650℃, 700℃, 750℃, 800℃, 900℃, 950℃, 1000℃, 1100℃, 1200℃, 1300℃, etc., including but not limited to the temperature values ​​listed above; more specifically, the nickel ore is calcined at the above temperature for 2-15 hours, such as 15 hours, 14 hours, 13 hours, 12 hours, 11 hours, 10 hours, 9 hours, 8 hours, 7 hours, 6 hours, 5 hours, 4 hours, 3 hours, 2 hours, etc., including but not limited to the time listed above.

[0046] In some preferred embodiments, in step (1), the calcined mineral material is crushed to obtain copper mixture particles, iron mixture particles, and nickel mixture particles with a median particle size D50 of 2-6 μm, for example, D50 values ​​within the ranges of 2-3.0 μm, 3.0-4.0 μm, 4.0-5.0 μm, and 5.0-6.0 μm. Crushing large-particle mineral material before calcination reduces the particle size of the mineral material to increase the contact area with air, thereby allowing the mineral material to react better with oxygen to generate the corresponding oxides.

[0047] For example, in step (1), chalcocite, hematite, and nickel ore are calcined at 600℃, 600℃, and 650℃ for 10 hours respectively in an air atmosphere. Then, the products of each mineral material after calcination are crushed to obtain copper mixture particles, iron mixture particles, and nickel mixture particles with a particle size D50 in the range of 3-5μm.

[0048] In some preferred embodiments, in step (2), the copper mixture particles, iron mixture particles and nickel mixture particles prepared in step (1) are subjected to magnetic separation by controlling the magnetic strength of the demagnetizing device to obtain copper-containing mixture, iron-containing mixture and nickel-containing mixture, while removing some mineral impurities; wherein the mass percentage of copper-containing mixture, iron-containing mixture and nickel-containing mixture in the original metal (copper, iron or nickel) mixture particles is not less than 75%.

[0049] In some preferred embodiments, in step (2), the mass percentage of copper in the copper-containing mixture is preferably 71-79 wt%, more preferably 60-79%, wherein the copper-containing mixture contains one or two of CuO and CuS; the mass percentage of iron in the iron-containing mixture is preferably 52.5-69.3%, more preferably 63-69%, wherein the iron-containing mixture contains one or more of FeO, Fe2O3, and Fe3O4; the mass percentage of nickel in the nickel-containing mixture is preferably 58.9-77.8%, more preferably 70-77 wt%, wherein the nickel-containing mixture contains one or more of NiO, Ni2O3, and Ni3O4.

[0050] In some preferred embodiments, in step (3), the manganese-containing compound is selected from one or more of potassium permanganate, potassium manganate, and manganese oxide; the sodium-containing compound is selected from one or more of sodium carbonate, sodium hydroxide, sodium oxide, sodium peroxide, sodium phosphate, sodium sulfate, sodium dihydrogen phosphate, sodium dihydrogen sulfate, and sodium phenolate.

[0051] Specifically, the present invention first determines the theoretical content ratio of copper in the copper-containing mixture, the theoretical content ratio of iron in the iron-containing mixture, and the theoretical content ratio of nickel in the nickel-containing mixture through testing. Then, according to the stoichiometric ratio of the metal elements sodium, nickel, iron, copper, and manganese in the cathode material, the corresponding sodium-containing compound, nickel-containing mixture, iron-containing mixture, copper-containing mixture, and manganese-containing compound are weighed.

[0052] In some preferred embodiments, in step (3), the solvent is ethanol and / or N-methylpyrrolidone; the drying temperature is 80-110°C, such as 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, etc., and the drying time is 5-15h, such as 5h, 6h, 7h, 8h, 9h, 12h, 14h, 15h, etc., including but not limited to the temperatures or times listed above; for example, copper-containing mixtures, iron-containing mixtures, nickel-containing mixtures, manganese-containing compounds, and sodium-containing compounds weighed according to stoichiometric ratios are placed in ethanol and stirred until uniformly mixed, and dried at 100°C for 12h to obtain uniformly mixed precursor powder.

[0053] In some preferred embodiments, in step (4), the temperature of the second calcination treatment is 700-1100℃, such as 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃, etc., including but not limited to the temperature values ​​listed above; more specifically, the precursor powder is calcined at the above temperature for 8-20h, such as 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, etc., including but not limited to the times listed above.

[0054] In addition, the embodiments of the present invention also provide a cathode material, a low-cost self-doped sodium-ion battery cathode material prepared by the above preparation method.

[0055] The embodiments of the present invention also provide a positive electrode sheet comprising the above-described positive electrode material.

[0056] In some preferred embodiments, the positive electrode sheet is prepared using a wet process, specifically: a positive electrode material, a conductive agent, and a binder are mixed to form a positive electrode slurry, which is then coated onto a positive electrode current collector and dried, rolled, cut, and slit to form the positive electrode sheet. The conductive agent can be selected from one or more of oligowalled carbon nanotubes, single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, conductive carbon black, conductive graphite, and graphene; the binder can be selected from one or more of monomers of acrylonitrile, vinylidene fluoride, vinyl alcohol, carboxymethyl cellulose, lithium carboxymethyl cellulose, sodium carboxymethyl cellulose, methacrylamide, acrylic acid, lithium acrylate, acrylamide, imide, acrylate, styrene-butadiene rubber, sodium alginate, chitosan, ethylene glycol, and guar gum, as well as polymers and copolymers of the above monomers; the positive electrode current collector can be aluminum foil, foamed aluminum foil, or nickel-plated aluminum foil.

[0057] For example, the positive electrode material is mixed with conductive carbon black and PVDF binder at a mass ratio of 90:5:5, and the mixture is coated onto aluminum foil after being mixed with NMP as a solvent. After vacuum drying, it is rolled, cut into sheets, and slit to form a positive electrode sheet.

[0058] The embodiments of the present invention also provide a sodium-ion battery comprising the above-described positive electrode material or positive electrode sheet.

[0059] The present invention will be further described below with reference to specific embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.

[0060] Example 1

[0061] This embodiment relates to the preparation of a self-doped sodium-ion battery cathode material, and the specific operations are as follows:

[0062] (1) In an air atmosphere, chalcocite, hematite and chalcopyrite were calcined at 600℃, 600℃ and 650℃ for 10h respectively. Then, the products of each mineral material after calcination were crushed to control the D50 of the particles to 3μm, and the corresponding copper mixture particles, iron mixture particles and nickel mixture particles were obtained.

[0063] (2) The copper mixture particles, iron mixture particles and nickel mixture particles obtained in step (1) are screened by a strong magnetic demagnetizing device. The rotation speed of the demagnetizing device is controlled at 30 r / min and the magnetic field is greater than 120 mT. High magnetic copper mixture, iron mixture and nickel mixture are obtained by screening. Then, the mass ratio of copper, iron and nickel in the copper mixture, iron mixture and nickel mixture is tested by inductively coupled plasma (ICP). The copper content in the copper mixture is 75.88%, the iron content in the iron mixture is 66.5% and the nickel content in the nickel mixture is 74.65%.

[0064] (3) Weigh the copper-containing mixture, iron-containing mixture, nickel-containing mixture, MnO2, and Na2CO3 prepared in step (2) according to the molar ratio of Cu:Fe:Ni:Mn:Na of 0.08:0.33:0.24:0.31:1, and place them in an ethanol solution for stirring. After mixing evenly, dry at 100℃ for 12h to obtain precursor powder.

[0065] (4) The precursor powder was calcined at 950°C for 15 hours in an air atmosphere to obtain the cathode material.

[0066] The ICP detection results of the cathode material prepared in this embodiment are shown in Table 1 below. The ICP detection results indicate that the cathode material is Na. 0.86 [Ni 0.23 Fe 0.33 Mn 0.31 Cu 0.07 M' 0.06 O2.

[0067] The Na prepared in this embodiment 0.86 [Ni 0.23 Fe 0.33 Mn 0.31 Cu 0.07 M' 0.06 The O2 material was characterized by XRD, and the characterization results are as follows: Figure 1 As shown, the cathode material prepared in Example 1 has diffraction peaks similar to those of O3 in the R3m space group.

[0068] Example 2

[0069] This embodiment relates to the preparation of a self-doped sodium-ion battery cathode material, and the specific operations are as follows:

[0070] (1) In an air atmosphere, chalcocite, hematite and nickel ore were calcined at 800℃ for 10h, and then the products of each mineral material after calcination were crushed to control the D50 of the particles to 3μm, so as to obtain the corresponding copper mixture particles, iron mixture particles and nickel mixture particles.

[0071] (2) The copper mixture particles, iron mixture particles and nickel mixture particles obtained in step (1) are screened by a strong magnetic demagnetizing device. The rotation speed of the demagnetizing device is controlled at 20 r / min and the magnetic field is greater than 120 mT. High magnetic copper mixture, iron mixture and nickel mixture are obtained by screening. Then, the mass ratio of copper, iron and nickel in the copper mixture, iron mixture and nickel mixture is tested by ICP. The copper content in the copper mixture is 75.88%, the iron content in the iron mixture is 66.5% and the nickel content in the nickel mixture is 74.65%.

[0072] (3) Weigh the copper-containing mixture, iron-containing mixture, nickel-containing mixture, MnO2, and Na2CO3 prepared in step (2) according to the molar ratio of Cu:Fe:Ni:Mn:Na of 0.1:0.30:0.24:0.3:1.04, and place them in an ethanol solution for stirring. After mixing evenly, dry at 100℃ for 12h to obtain precursor powder.

[0073] (4) The precursor powder was calcined at 950°C for 15 hours in an air atmosphere to obtain the cathode material.

[0074] The ICP detection results of the cathode material prepared in this embodiment are shown in Table 1. The ICP detection results indicate that the cathode material is Na. 0.9 [Ni 0.23 Fe 0.32 Mn 0.30 Cu 0.1 M' 0.05 O2.

[0075] Example 3

[0076] This embodiment relates to the preparation of a self-doped sodium-ion battery cathode material, and the specific operations are as follows:

[0077] (1) In an air atmosphere, chalcocite, hematite and chalcopyrite were calcined at 600℃, 600℃ and 650℃ for 10h respectively. Then, the products of each mineral material after calcination were crushed to control the D50 of the particles to 3μm, and the corresponding copper mixture particles, iron mixture particles and nickel mixture particles were obtained.

[0078] (2) The copper mixture particles, iron mixture particles and nickel mixture particles obtained in step (1) are screened by a strong magnetic demagnetizing device. The rotation speed of the demagnetizing device is controlled at 20 r / min and the magnetic field is greater than 70 mT. High magnetic copper mixture, iron mixture and nickel mixture are obtained by screening. Then, the mass ratio of copper, iron and nickel in the copper mixture, iron mixture and nickel mixture is tested by ICP. The copper content in the copper mixture is 67.87%, the iron content in the iron mixture is 66.79% and the nickel content in the nickel mixture is 59.5%.

[0079] (3) Weigh the copper-containing mixture, iron-containing mixture, nickel-containing mixture, MnO2, and Na2CO3 prepared in step (2) according to the molar ratio of Cu:Fe:Ni:Mn:Na of 0.03:0.34:0.23:0.4:1.0, and place them in an ethanol solution for stirring. After mixing evenly, dry at 100℃ for 12h to obtain precursor powder;

[0080] (4) The precursor powder was calcined at 950°C for 15 hours in an air atmosphere to obtain the cathode material.

[0081] The ICP detection results of the cathode material prepared in this embodiment are shown in Table 1 below. The ICP detection results indicate that the cathode material is Na. 0.85 [Ni 0.22 Fe 0.34 Mn 0.40 Cu 0.02 M' 0.02 O2.

[0082] Example 4

[0083] This embodiment relates to the preparation of a self-doped sodium-ion battery cathode material, and the specific operations are as follows:

[0084] (1) In an air atmosphere, chalcocite, hematite and chalcopyrite were calcined at 600℃, 600℃ and 650℃ for 10h respectively. Then, the products of each mineral material after calcination were crushed to control the D50 of the particles to 3μm, and the corresponding copper mixture particles, iron mixture particles and nickel mixture particles were obtained.

[0085] (2) The copper mixture particles, iron mixture particles and nickel mixture particles obtained in step (1) are screened by a strong magnetic demagnetizing device. The rotation speed of the demagnetizing device is controlled at 30 r / min and the magnetic field is 120 mT. High magnetic copper mixture, iron mixture and nickel mixture are obtained by screening. Then, the mass ratio of copper, iron and nickel in the copper mixture, iron mixture and nickel mixture is tested by ICP. The copper content in the copper mixture is 78.87%, the iron content in the iron mixture is 68.6% and the nickel content in the nickel mixture is 77.01%.

[0086] (3) Weigh the copper-containing mixture, iron-containing mixture, nickel-containing mixture, MnO2, and Na2CO3 prepared in step (2) according to the molar ratio of Cu:Fe:Ni:Mn:Na of 0.03:0.34:0.27:0.34:1.05, and place them in an ethanol solution for stirring. After mixing evenly, dry at 100℃ for 12h to obtain precursor powder.

[0087] (4) The precursor powder was calcined at 900°C for 15 hours in an air atmosphere to obtain the cathode material.

[0088] The ICP detection results of the cathode material prepared in this embodiment are shown in Table 1 below. The ICP detection results indicate that the cathode material is Na. 0.97 [Ni 0.27 Fe 0.34 Mn 0.34 Cu 0.03 M' 0.02 O2.

[0089] Example 5

[0090] This embodiment relates to the preparation of a self-doped sodium-ion battery cathode material, and the specific operations are as follows:

[0091] (1) In an air atmosphere, chalcocite, hematite and chalcopyrite were calcined at 600℃, 600℃ and 650℃ for 10h respectively. Then, the products of each mineral material after calcination were crushed to control the D50 of the particles to 5μm, and the corresponding copper mixture particles, iron mixture particles and nickel mixture particles were obtained.

[0092] (2) The copper mixture particles, iron mixture particles and nickel mixture particles obtained in step (1) are screened by a strong magnetic demagnetizing device. The rotation speed of the demagnetizing device is controlled at 30 r / min and the magnetic field is greater than 70 mT. High magnetic copper mixture, iron mixture and nickel mixture are obtained by screening. The mass ratio of copper, iron and nickel in the copper mixture, iron mixture and nickel mixture is tested by ICP. The copper content in the copper mixture is 78.87%, the iron content in the iron mixture is 68.6% and the nickel content in the nickel mixture is 77.01%.

[0093] (3) Weigh the copper-containing mixture, iron-containing mixture, nickel-containing mixture, MnO2, and Na2CO3 prepared in step (2) according to the molar ratio of Cu:Fe:Ni:Mn:Na of 0.03:0.34:0.23:0.4:1.02, and place them in an ethanol solution for stirring. After mixing evenly, dry at 100℃ for 12h to obtain precursor powder;

[0094] (4) The precursor powder was calcined at 950°C for 12 hours in an air atmosphere to obtain the cathode material.

[0095] The ICP detection results of the cathode material prepared in this embodiment are shown in Table 1 below. The ICP detection results indicate that the cathode material is Na. 0.9 [Ni 0.22 Fe 0.34 Mn 0.40 Cu 0.02 M' 0.02 O2.

[0096] Example 6

[0097] This embodiment relates to the preparation of a self-doped sodium-ion battery cathode material, and the specific operations are as follows:

[0098] (1) In an air atmosphere, chalcocite, hematite and chalcopyrite were calcined at 600℃, 600℃ and 650℃ for 10h respectively. Then, the products of each mineral material after calcination were crushed to control the D50 of the particles to 3μm, and the corresponding copper mixture particles, iron mixture particles and nickel mixture particles were obtained.

[0099] (2) The copper mixture particles, iron mixture particles and nickel mixture particles obtained in step (1) are screened by a strong magnetic demagnetizing device. The rotation speed of the demagnetizing device is controlled at 20 r / min and the magnetic field is 70 mT. After screening, copper mixture, iron mixture and nickel mixture are obtained. The mass ratio of copper, iron and nickel in copper mixture, iron mixture and nickel mixture is tested by ICP. The copper content in copper mixture is 63.9%, the iron content in iron mixture is 56.0% and the nickel content in nickel mixture is 62.86%.

[0100] (3) Weigh the copper-containing mixture, iron-containing mixture, nickel-containing mixture, MnO2, and Na2CO3 prepared in step (2) according to the molar ratio of Cu:Fe:Ni:Mn:Na of 0.04:0.34:0.24:0.34:1.02, and place them in an ethanol solution for stirring. After mixing evenly, dry at 100℃ for 12h to obtain precursor powder.

[0101] (4) The precursor powder was calcined at 1000°C for 15 hours in an air atmosphere to obtain the cathode material.

[0102] The ICP detection results of the cathode material prepared in this embodiment are shown in Table 1 below. The ICP detection results indicate that the cathode material is Na. 0.88 [Ni 0.23 Fe 0.33 Mn 0.33 Cu 0.04 M' 0.07 O2.

[0103] Comparative Example 1

[0104] This comparative example relates to the preparation of a cathode material, and the specific operations are as follows:

[0105] Na2CO3 and Ni 0.34 Fe 0.33 Mn 0.33 O2 was weighed according to the molar ratio of Na:Ni:Fe:Mn of 1.05:0.34:0.33:0.33, and then ground and mixed evenly to obtain precursor powder. The precursor powder was then calcined at 1000℃ for 15 hours in air to obtain the cathode material.

[0106] The ICP detection results of the cathode material prepared in this comparative example are shown in Table 1 below. The ICP detection results indicate that the cathode material is NaNi. 0.34 Fe 0.33 Mn 0.33 O2.

[0107] Comparative Example 2

[0108] Layered oxide (XN33S) purchased from Jiangsu Xiangying New Energy Technology Co., Ltd.

[0109] The ICP test results of the cathode materials prepared in the above embodiments and Comparative Example 1 are shown in Table 1 below:

[0110] Table 1

[0111]

[0112] M' represents all elements greater than 300 ppm, including Zn, Mo, Co, Cr, Al, Ti, and Ca.

[0113] Application and performance testing

[0114] Using the positive electrode materials prepared or purchased in the above embodiments and comparative examples as positive electrode active materials, positive electrode sheets were prepared and coin cells were assembled. The specific preparation process is as follows:

[0115] The positive electrode active material is mixed with conductive carbon black and PVDF binder in a mass ratio of 90:5:5. After mixing with NMP as solvent, the mixture is coated onto aluminum foil, dried under vacuum at 100℃, rolled, cut, and slit to obtain the positive electrode sheet.

[0116] A battery is assembled from a positive electrode, a counter electrode (sodium metal), an electrolyte (1 mol / L NaPF6 EC:DEC = 1:1) and a glass fiber separator.

[0117] The assembled button cells were subjected to the following performance tests:

[0118] Initial coulombic efficiency: The coin cell was placed in an environment of 25±2℃ and left to stand for 8 hours. Then it was charged at a constant current of 0.05C to 4.0V. The resulting capacity was recorded as the 0.05C charging capacity. After that, it was left to stand for 5 minutes. Then it was discharged at a constant current of 0.1C to 3.0V. The resulting capacity was recorded as the 0.1C discharging capacity. Finally, the operation was stopped. The initial coulombic efficiency was 0.1C discharging capacity / 0.05C charging capacity.

[0119] Discharge capacity test corresponding to a current density of 0.2C: The coin cell was placed in an environment of 25±2℃ and left to stand for 8 hours. Then it was charged with a constant current of 0.2C to 4.0V, left to stand for 5 minutes, then discharged with a constant current of 0.2C to 2.0V, left to stand for 5 minutes, then charged with a constant current of 0.2C to 4.0V, left to stand for 5 minutes, and then discharged with a constant current of 0.2C to 2.0V. The obtained capacity is the discharge capacity corresponding to 0.2C. Finally, the operation was stopped, and the discharge capacity corresponding to 0.2C was recorded.

[0120] Capacity retention rate after 200 cycles at 1C: Place the coin cell in an environment of 25±2℃ and let it stand for 8 hours. Then charge it with a constant current of 0.2C to 4.0V, let it stand for 5 minutes, then charge it with a constant voltage of 4.0V to a current of 0.05C, let it stand for 5 minutes, and then discharge it with a constant current of 0.2C to a voltage of 2.0V. Repeat this cycle 50 times, and finally stop the operation. Record the capacitance after the 1st and 200th discharge cycles. The capacitance retention rate is the capacitance after the 200th discharge cycle / the capacitance after the 1st discharge cycle.

[0121] The results of the above performance tests are shown in Table 2 below:

[0122] Table 2

[0123]

[0124] As shown in the table above, the cathode materials obtained by simple calcination, crushing and magnetic separation of raw mineral materials of iron, manganese and copper to obtain a highly magnetic mixture, and then solid-state sintering with other metal compounds (containing manganese compounds and sodium compounds) in Examples 1-6 have significantly lower costs compared to the cathode materials purchased in Comparative Examples 1 and 2 which are prepared using precursor salts.

[0125] Furthermore, the coin cells assembled using the cathode materials prepared in Examples 1-6 as cathode active materials have similar or better initial coulombic efficiencies than Comparative Examples 1 and 2, and there is no significant difference in discharge capacity at a current density of 0.2C. In high-rate charge-discharge cycle tests, the coin cells constructed in Examples 1-6 all have a capacity retention rate of more than 90% after 200 cycles at 1C. Among them, the coin cells constructed in Examples 1-3 have better cycle performance than the cells corresponding to Comparative Examples 1 and 2.

[0126] The embodiments described above are merely preferred examples to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A method for preparing a sodium-ion battery cathode material, characterized in that, Includes the following steps: (1) The copper ore, iron ore and nickel ore are calcined for the first time, and then crushed to obtain the corresponding copper mixture particles, iron mixture particles and nickel mixture particles; the copper ore is chalcocite, the iron ore is hematite and the nickel ore is chalcopyrite. (2) The copper mixture particles, iron mixture particles and nickel mixture particles mentioned above are subjected to magnetic separation to obtain copper-containing mixture, iron-containing mixture and nickel-containing mixture; (3) Weigh the above copper-containing mixture, iron-containing mixture, nickel-containing mixture, manganese-containing compound, and sodium-containing compound according to the stoichiometric ratio of the metal elements sodium, nickel, iron, copper, and manganese in the cathode material, mix them in a solvent, and dry them after uniform mixing to obtain precursor powder. (4) The above precursor powder is subjected to a second calcination treatment to obtain the cathode material; The positive electrode material is Na. x [Ni a Fe b Mn c Cu d M' e O2, wherein M' contains one or more of Zn, Mo, Co, Cr, Al, Ti, and Ca, 0.85≤x≤1.2, 0<a≤0.4, 0<b≤0.4, 0<c≤0.4, d=0.1, 0<e≤0.1, and a+b+c+d+e=1.

2. The preparation method according to claim 1, characterized in that, In step (1), The copper ore undergoes its first calcination treatment at a temperature of 600-1500 ℃ for a duration of 2-15 h. The iron ore undergoes its first calcination treatment at a temperature of 300-900 ℃ for 2-15 h. The nickel ore undergoes its first calcination treatment at a temperature of 500-1300 ℃ for 2-15 h.

3. The preparation method according to claim 1, characterized in that, In step (1), the median particle size D50 of the copper mixture particles, iron mixture particles and nickel mixture particles is 0.5-30 μm.

4. The preparation method according to claim 1, characterized in that, In step (2), the mass percentage of the copper-containing mixture in the copper mixture particles is not less than 75%, the mass percentage of copper element in the copper-containing mixture is 60-79%, and the copper-containing mixture contains one or two of CuO and CuS. The iron-containing mixture accounts for no less than 75% of the mass of the iron mixture particles, and the mass percentage of iron element in the iron-containing mixture is 52.5-69.3%. The iron-containing mixture contains one or more of FeO, Fe2O3, and Fe3O4. The nickel-containing mixture accounts for no less than 75% of the mass of the nickel mixture particles, and the mass percentage of nickel element in the nickel-containing mixture is 58.9-77.8%. The nickel-containing mixture contains one or more of NiO, Ni2O3, and Ni3O4.

5. The preparation method according to claim 1, characterized in that, In step (3), The manganese-containing compound is selected from one or more of potassium permanganate, potassium manganate, and manganese oxide; The sodium-containing compound is selected from one or more of sodium carbonate, sodium hydroxide, sodium oxide, sodium peroxide, sodium phosphate, sodium sulfate, sodium dihydrogen phosphate, sodium dihydrogen sulfate, and sodium phenolate.

6. The preparation method according to claim 1, characterized in that, In step (3), the solvent is ethanol and / or N-methylpyrrolidone.

7. The preparation method according to claim 1, characterized in that, In step (4), the temperature of the second calcination treatment is 700-1100 ℃, and the calcination time is 8-20 h.

8. A positive electrode material, characterized in that, The cathode material is prepared by the preparation method described in any one of claims 1-7.

9. A positive electrode sheet, characterized in that, The positive electrode sheet comprises the positive electrode material as described in claim 8.

10. A sodium-ion battery, characterized in that, The sodium-ion battery comprises the positive electrode material of claim 8, or the positive electrode sheet of claim 9.

Images