WO2024164409A1 - Coated lithium-sodium composite ternary positive electrode material and preparation method therefor - Google Patents

Coated lithium-sodium composite ternary positive electrode material and preparation method therefor Download PDF

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WO2024164409A1
WO2024164409A1 PCT/CN2023/083934 CN2023083934W WO2024164409A1 WO 2024164409 A1 WO2024164409 A1 WO 2024164409A1 CN 2023083934 W CN2023083934 W CN 2023083934W WO 2024164409 A1 WO2024164409 A1 WO 2024164409A1
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sodium
positive electrode
lithium
electrode material
ternary positive
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PCT/CN2023/083934
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French (fr)
Chinese (zh)
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李志�
李长东
阮丁山
刘伟健
刘婧婧
程江辉
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广东邦普循环科技有限公司
湖南邦普循环科技有限公司
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Publication of WO2024164409A1 publication Critical patent/WO2024164409A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the technical field of lithium-ion positive electrode materials, and in particular to a coated lithium-sodium composite ternary positive electrode material and a preparation method thereof.
  • lithium ion batteries In order to reduce the cost of new energy batteries and promote the rapid development of new energy technologies, sodium, which has a lower price, more abundant reserves and more uniform distribution, has received more and more attention. Lithium and sodium have similar properties, with a standard electrode potential difference of 0.3V and similar electrochemical mechanisms. Many electrode materials with similar structures can be used in both sodium ion and lithium ion batteries. Therefore, sodium can be used to partially replace lithium in lithium ion batteries, which can not only reduce costs, but also improve the performance of lithium ion batteries due to the unique properties of sodium ions.
  • the structure of sodium ion batteries is mainly divided into P2 phase and O3 phase.
  • O3 phase sodium exists in the form of octahedron, which has high capacity, but is prone to phase change, resulting in unstable material structure.
  • P2 phase sodium exists in the form of triangular prisms.
  • the ion diffusion rate is fast and the crystal structure is stable, which can improve the battery's cycle and rate performance.
  • the main method is to use doping to make sodium enter the crystal structure to improve some of the performance of lithium-ion batteries.
  • ternary positive electrode materials Compared with traditional LiCoO2 and LiFePO4 materials, ternary positive electrode materials have become one of the most promising positive electrode materials due to their advantages such as high capacity and low cost. Therefore, the preparation of lithium-sodium composite ternary positive electrode materials is one of the current research directions of lithium-ion batteries.
  • a method for preparing a positive electrode material for a sodium ion battery comprising preparing a hydroxide precursor Ni a Mn b Mc (OH) 2 , then mixing a lithium source, a sodium source and the hydroxide precursor evenly and then solid-phase sintering them to obtain a Na x Li y Ni a Mn b McO 2 positive electrode material, wherein 0.44 ⁇ x ⁇ 1, and the positive electrode material has certain P2 and O3 phases.
  • Na accounts for too much, and for lithium ion battery positive electrode materials, the sodium doping amount is too high. High concentrations will lead to material performance degradation; and the imbalance of P2 and O3 phases in the positive electrode material prepared by this method also affects the electrochemical performance of the positive electrode material.
  • the purpose of the present application is to overcome the defects of poor electrochemical performance in the prior art and provide a method for preparing a coated lithium-sodium composite ternary positive electrode material.
  • a sodium ion ternary positive electrode material whose main crystal phase is a P2 phase is prepared, and then the sodium ion ternary positive electrode material, a lithium precursor and a ternary precursor are mixed and sintered again to prepare a lithium-sodium composite ternary positive electrode material in which P2 and O3 coexist, and then a coating modification is performed to obtain a coated lithium-sodium composite ternary positive electrode material.
  • the coated lithium-sodium composite ternary positive electrode material of the present application has excellent electrochemical properties.
  • Another object of the present application is to provide a coated lithium-sodium composite ternary positive electrode material prepared by the above preparation method.
  • a coated lithium-sodium composite ternary positive electrode material has the general formula: NaxLi0.9 ( NiyCozMn1 -yz ) O2 @A, wherein x is 0.027-0.1, y is 0.55-0.8, z is 0.02-0.05, A is an oxide of a coating element, and the coating element is at least one of Ti, B, Co, Al, W, Zr and Sr.
  • the coated lithium-sodium composite ternary positive electrode material has a morphology of spherical or quasi-spherical particles with an average particle size of 2 to 5 ⁇ m.
  • the present application also protects a method for preparing the above-mentioned coated lithium-sodium composite ternary positive electrode material, comprising the following steps:
  • the sodium ion ternary positive electrode material, the lithium source and the Ni y Co z Mn 1-yz (OH) 2 ternary precursor obtained in step S1 are mixed and sintered for a second time to obtain a lithium-sodium composite ternary positive electrode material (Na x Li 0.9 (Ni y Co z Mn 1-yz )O 2 ), wherein the molar ratio of the sodium ion ternary positive electrode material: the lithium in the lithium source: (the total molar amount of Ni, Co and Mn elements in the Ni y Co z Mn 1-yz (OH) 2 ternary precursor) is (0.08-0.18): 0.9: 0.9, and the lithium source is in excess of 5-8 wt.% on this basis;
  • the preparation method of the present application prepares a sodium ion ternary positive electrode material whose main crystal phase is the P2 phase, and then mixes and sinters the sodium ion ternary positive electrode material, a lithium source and a Ni y Co z Mn 1-yz (OH) 2 ternary precursor again to obtain a lithium-sodium composite ternary positive electrode material in which P2 and O3 phases coexist, and then performs coating modification to obtain a coated lithium-sodium composite ternary positive electrode material.
  • the coated lithium-sodium composite ternary positive electrode material prepared by the preparation method has coexisting P2 phase and O3 phase, and the content of the two phases is appropriate; Na is doped in a relatively low amount, which reduces the cost of the material on the one hand, and improves the electrochemical properties of the positive electrode material on the other hand; the surface coating agent reduces the corrosion effect of the electrolyte on the lithium-sodium composite positive electrode material, and further improves the cycle performance of the lithium-sodium composite ternary positive electrode material.
  • the main crystal phase of the sodium ion ternary positive electrode material prepared in step S1 is a P2 phase formed by Na + , and then after mixed sintering in step S2, a certain amount of O3 phase is formed by Li + , which can achieve the coexistence of P2 phase and O3 phase in a suitable ratio in the lithium-sodium composite ternary positive electrode material, improve the ion diffusion rate, stabilize the crystal structure, and improve the cycle and rate performance of the battery, thereby improving the electrochemical performance.
  • the doping amount of the sodium element is below 0.1, which achieves that the material performance will not be attenuated due to excessive sodium doping, and ensures that the P2 phase content is appropriate, thereby playing a role in stabilizing the crystal structure of the material.
  • the weighed amounts of the sodium source and the Ni y Co z Mn 1-yz (OH) 2 ternary precursor are according to a molar ratio of sodium in the sodium source: (total molar amount of Ni, Co and Mn elements in the Ni y Co z Mn 1-yz (OH) 2 ternary precursor) of (0.27-1):1, and the sodium source is weighed in an excess of 1-5 wt.% on this basis.
  • Ni, Co, and Mn as transition metals, contribute to better electrochemical performance of the positive electrode material in appropriate proportions.
  • the sodium source is at least one of sodium carbonate, sodium hydroxide, sodium nitrate and sodium chloride.
  • the lithium source is at least one of lithium carbonate, lithium hydroxide, lithium nitrate and lithium chloride.
  • the coating agent is a compound containing a coating element, and the coating element is at least one of Ti, B, Co, Al, W, Zr, and Sr.
  • the coating element is at least one of Ti, Co and B.
  • the compound may be an oxide, a hydroxide or an acid.
  • the compound containing Ti is TiO 2
  • the compound containing B is H 3 BO 3
  • the compound containing Co is CoOOH.
  • the coating agent can reduce the corrosion of the electrolyte on the lithium-sodium composite positive electrode material, thereby improving the cycle performance of the lithium-sodium composite ternary positive electrode material.
  • Ti, Co, and B elements have a relatively better effect on the corrosion improvement of lithium-sodium composite ternary positive electrode materials, especially the coated lithium-sodium composite ternary positive electrode material prepared by the coating agent containing B and Ti elements has excellent cycle performance.
  • the molar ratio of sodium ion ternary positive electrode material: lithium in the lithium source: (total molar amount of Ni, Co and Mn elements in Ni y Co z Mn 1-y z (OH) 2 ternary precursor) is 0.1:0.9:0.9, and the lithium source is in excess of 5-8 wt.%.
  • step S3 a coating agent is weighed and added according to a weight ratio of 0.2 to 0.7 wt.% of the weight of the coating element to the lithium-sodium composite ternary positive electrode material.
  • step S3 after mixing and sintering, the coating material finally coated on the surface of the lithium-sodium composite ternary positive electrode material is an oxide containing a coating element. Therefore, the amount of coating agent added is calculated and weighed according to the weight relationship of the coating element. The inventors have found that when the weight of the coating element accounts for 0.2-0.7wt.% of the lithium-sodium composite ternary positive electrode material, a good coating modification effect can be achieved, making the cycle performance of the coated lithium-sodium composite ternary positive electrode material better, and the excessive coating will not affect the electrical performance of the lithium-sodium composite ternary positive electrode material.
  • the first sintering condition is to heat to 750-850°C and sinter for 15-24h at a heating rate of 3-5°C/min in an air atmosphere with a flow rate of 4-10m3 /h.
  • the second sintering conditions are: heating to 700-800°C at a heating rate of 3-5°C/min for 2-4h in an air atmosphere with a flow rate of 4-10m3 /h, and then heating to 850-950°C at a heating rate of 2-5°C/min for 10-15h.
  • the third sintering condition is to heat to 300-700° C. at a heating rate of 2-5° C./min and sinter for 4-8 hours.
  • the present application develops a coated lithium-sodium composite ternary positive electrode material and a preparation method thereof.
  • a sodium ion ternary positive electrode material whose main crystal phase is the P2 phase is first prepared, and then the sodium ion ternary positive electrode material, the lithium precursor and the ternary precursor are mixed and sintered again to prepare a lithium-sodium composite ternary positive electrode material in which P2 and O3 phases coexist, and then the coated modification is performed to obtain a coated lithium-sodium composite ternary positive electrode material.
  • the stoichiometric ratio of lithium in the coated lithium-sodium composite ternary positive electrode material of the present application is reduced from 1 to 0.9, which effectively reduces the cost, and the coated lithium-sodium composite ternary positive electrode material has excellent electrochemical properties.
  • FIG. 1 is a SEM image of the coated lithium-sodium composite ternary positive electrode material prepared in Example 1.
  • FIG. 2 is an XRD diagram of the coated lithium-sodium composite ternary positive electrode materials prepared in Example 3 and Comparative Example 1.
  • the present application will be further described below in conjunction with specific embodiments, but the embodiments do not limit the present application in any form.
  • the reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the art.
  • the reagents and materials used in the present application are commercially available.
  • Example 1 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is as follows:
  • the sodium source and the ternary precursor (Ni 0.53 Co 0.02 Mn 0.45 (OH) 2 ) were mixed uniformly in a high-speed mixer, placed in a box furnace, heated to 750° C. at a heating rate of 3° C./min in an air atmosphere with a flow rate of 4 m 3 /h, and sintered for 24 hours; after sintering, the mixture was cooled to below 200° C. in the furnace, and passed through a 300-mesh sieve to obtain a sodium ion ternary positive electrode material (Na 0.9 (Ni 0.53 Co 0.02 Mn 0.45 )O 2 ), the main crystal phase of which was the P2 phase;
  • step S2 weigh Na 0.9 (Ni 0.53 Co 0.02 Mn 0.45 )O 2 , a lithium source (lithium hydroxide) and a ternary precursor (Ni 0.53 Co 0.02 Mn 0.45 (OH) 2 ) prepared in step S1 according to a Na 0.9 (Ni 0.53 Co 0.02 Mn 0.45 )O 2 :Li:Me molar ratio of 0.1:0.9:0.9, with the mass of the lithium source being in excess of 7wt%;
  • the raw materials are mixed evenly in a high-speed mixer, they are placed in a box furnace and heated to 800°C at a heating rate of 3°C/min in an air atmosphere with a flow rate of 10m 3 /h and kept at that temperature for 2h. Then, they are heated to 850°C at a heating rate of 2°C/min and sintered for 15h.
  • the sample was cooled to below 200°C in the furnace and passed through a 300-mesh sieve to obtain a lithium-sodium composite ternary cathode material (Na 0.09 Li 0.9 (Ni 0.53 Co 0.02 Mn 0.45 )O 2 ), with a crystal phase of coexistence of P2 and O3.
  • the sample was cooled to below 200°C in the furnace, and passed through a 300-mesh sieve to obtain the final coated lithium-sodium composite ternary positive electrode material (Na 0.09 Li 0.9 (Ni 0.53 Co 0.02 Mn 0.45 )O 2 @B 2 O 3 ).
  • Example 2 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
  • step S3 coating agent TiO 2 is weighed and added according to a weight ratio of Ti to 0.5 wt.% of the lithium-sodium composite ternary positive electrode material.
  • Example 3 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
  • step S3 the coating agent CoOOH is weighed and added according to a weight ratio of 0.5 wt.% of the weight of Co to the lithium-sodium composite ternary positive electrode material.
  • Example 4 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
  • step S3 H 3 BO 3 is added according to a weight ratio of 0.2 wt.% of B to the lithium-sodium composite ternary positive electrode material, and TiO 2 is added according to a weight ratio of 0.3 wt.% of Ti to the lithium-sodium composite ternary positive electrode material; H 3 BO 3 and TiO 2 are mixed as coating agents.
  • Example 5 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
  • the molar ratio of Na/Me in step S1 is 0.8:1.
  • Example 6 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
  • the molar ratio of Na/Me in step S1 is 0.5:1.
  • Example 7 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
  • the molar ratio of Na/Me in step S1 is 0.27:1.
  • Example 8 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
  • the ternary precursor Ni 0.53 Co 0.02 Mn 0.45 (OH) 2 was replaced by Ni 0.60 Co 0.05 Mn 0.35 (OH) 2 .
  • Example 9 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
  • the ternary precursor Ni 0.53 Co 0.02 Mn 0.45 (OH) 2 was replaced by Ni 0.8 Co 0.03 Mn 0.17 (OH) 2 .
  • Example 10 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
  • step S3 a coating agent (H 3 BO 3 ) is weighed and added in a weight ratio of 0.2 wt.% of the weight of the lithium-sodium composite ternary positive electrode material.
  • Example 11 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
  • step S3 a coating agent (H 3 BO 3 ) is weighed and added in a weight ratio of 0.7 wt.% of the weight of the lithium-sodium composite ternary positive electrode material.
  • Example 12 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
  • the sodium source is replaced by sodium hydroxide, and the lithium source is replaced by lithium carbonate.
  • Example 13 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
  • step S2 the molar ratio of Na 0.9 (Ni 0.53 Co 0.02 Mn 0.45 )O 2 :Li:Me is 0.18:0.9:0.9.
  • Example 14 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
  • step S1 the sintering conditions are: heating to 850°C at a heating rate of 5°C/min and sintering for 15h in an air atmosphere with a flow rate of 10m3 /h;
  • step S2 the sintering conditions are: heating to 700°C at a heating rate of 5°C/min and keeping the temperature for 4 hours in an air atmosphere with a flow rate of 4m 3 /h, and then heating to 950°C at a heating rate of 5°C/min and sintering for 10 hours;
  • step S3 the sintering conditions are: heating to 700° C. at a heating rate of 5° C./min and sintering for 4 h.
  • Comparative Example 1 provides a positive electrode material, and the preparation method is as follows:
  • the raw materials are mixed evenly in a high-speed mixer, they are placed in a box furnace and heated to 750°C at a heating rate of 3°C/min in an air atmosphere with a flow rate of 6m 3 /h for 2 hours, and then heated to 900°C at a heating rate of 2°C/min for sintering for 12 hours;
  • the sample was cooled to below 200°C in the furnace, and passed through a 300-mesh sieve to obtain a lithium-sodium composite ternary cathode material Na 0.08 Li 0.9 (Ni 0.6 Co 0.05 Mn 0.35 )O 2 in which P2 and O3 phases coexisted.
  • the coating agent H 3 BO 3 was weighed according to the weight of B accounting for 0.5 wt.% of the lithium-sodium composite ternary positive electrode material, and the prepared lithium-sodium composite ternary positive electrode material and the coating agent were mixed evenly by a ball mill, and heated to 550° C. at a heating rate of 2° C./min and sintered for 6 h.
  • Comparative Example 2 provides a positive electrode material, and the preparation method is as follows:
  • Lithium hydroxide and a precursor (Ni 0.60 Co 0.05 Mn 0.35 (OH) 2 ) were weighed in a Li:Me (Me is transition metal Ni+Co+Mn) molar ratio of 1:1, and the mass of lithium hydroxide was 7wt% in excess;
  • the raw materials are mixed evenly in the high-speed mixer, they are placed in a box furnace and heated to 750°C at a heating rate of 3°C/min in an air atmosphere with a flow rate of 6m3 /h. They are kept at this temperature for 2h and then heated to 940°C at a heating rate of 2°C/min. Sintering for 12 hours;
  • the sample was cooled to below 200°C in the furnace, and passed through a 300-mesh sieve to obtain the ternary positive electrode material Li(Ni 0.6 Co 0.05 Mn 0.35 )O 2 ;
  • the coating agent H 3 BO 3 was weighed according to the weight of B accounting for 0.5wt% of the ternary positive electrode material, and the prepared lithium sodium composite ternary positive electrode material and the coating agent were mixed evenly by a ball mill, and heated to 700°C at a heating rate of 2°C/min and sintered for 4h; after the sintering, the furnace was cooled to below 200°C, and the sample was passed through a 300-mesh sieve to obtain the B-coated lithium composite ternary positive electrode material.
  • Comparative Example 2 is not doped with sodium and does not contain the P2 phase.
  • Comparative Example 3 provides a positive electrode material, and the preparation method is different from that of Example 1 in that:
  • the molar ratio of Na/Me in step S1 is 0.1:1.
  • Comparative Example 4 provides a positive electrode material, and the preparation method is different from that of Example 1 in that:
  • step S2 the molar ratio of Na 0.9 (Ni 0.53 Co 0.02 Mn 0.45 )O 2 :Li:Me is 0.2:0.9:0.9.
  • Comparative Example 5 provides a positive electrode material, and the preparation method is different from that of Example 1 in that:
  • Step S3 is not performed, that is, coating modification is not performed.
  • the electrode sheet was prepared by a coating method; aluminum foil was used as the current collector, and the positive electrode component of the test battery was mixed with a positive electrode material, a conductive agent, and a binder, polytetraoxyethylene, in a mass ratio of 9:0.5:0.5.
  • the mixed slurry was evenly stirred for more than 45 minutes, and the mixed slurry was evenly applied to the aluminum foil current collector; after being dried with air at 110°C, it was cut into discs with a diameter of about 1.4 cm, and then the cut electrode sheets were placed in a vacuum dryer at 105°C for 4 hours to obtain the positive electrode sheet of the test battery; a metal lithium sheet was used as the negative electrode, and conventional commercial electrolytes and separators were used to assemble the positive and negative electrodes into a button-type test battery, and the first coulombic efficiency, the first charge and discharge specific capacity, and the discharge capacity retention rate of 50 cycles at 1C were tested.
  • SEM detection method Use scanning electron microscope to observe the sample morphology.
  • XRD detection method using X-ray diffraction analyzer, using Cu target K ⁇ radiation, the scanning range is 10 ⁇ 90°.
  • Figure 1 is a SEM image of the coated lithium sodium composite ternary positive electrode material prepared in Example 1.
  • Figure 2 is an XRD image of the coated lithium sodium composite ternary positive electrode material prepared in Example 3 and Comparative Example 1.
  • the characteristic peaks (002) and (004) of the P2 phase appear in the XRD diffraction pattern of the coated lithium-sodium composite ternary positive electrode material prepared in Example 3, which indicates that a certain amount of P2 phase exists in the prepared material.
  • the characteristic peaks (002) and (004) of the P2 phase in the material obtained by directly mixing and sintering the sodium source, lithium source and precursor in Comparative Example 1 are smaller, which also indicates that the P2 phase obtained in Comparative Example 1 is less than that in Example 3.
  • the positive electrode materials prepared in each embodiment of the present application have good electrochemical performance, with a first coulombic efficiency ⁇ 85.2%, a first charge specific capacity of 194.8 to 230.1 mAh/g, a first discharge specific capacity of 170.1 to 206.8 mAh/g, and a discharge capacity retention rate of ⁇ 81.2% after 50 cycles at 1C.
  • Comparative Example 1 instead of two-step sintering, a lithium-sodium composite ternary positive electrode material in which P2 phase and O3 phase coexist is obtained by sintering once, and then coating is performed. Sintering once alone will result in a lower content of P2 phase in the positive electrode material and affect the electrochemical performance of the material. Compared with Example 8, the electrochemical performance of Comparative Example 1 is deteriorated.
  • Comparative Example 5 is an uncoated positive electrode material. It can be seen that without coating, the cycle performance of the positive electrode material is poor due to the corrosion of the lithium-sodium composite positive electrode material by the electrolyte.

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Abstract

Provided in the present application are a coated lithium-sodium composite ternary positive electrode material and a preparation method therefor. The general formula of the lithium-sodium composite ternary positive electrode material of the present application is NaxLi0.9(NiyCozMn1-y-z)O2@A, wherein x is 0.027-0.1, y=0.55-0.8 and z=0.02-0.05, A is an oxide of a coating element, and the coating element is at least one of Ti, B, Co, Al, W, Zr and Sr. The method of the present application comprises first preparing a sodium ion ternary positive electrode material of which the main crystal phase is P2 phase, then performing mixing and sintering again on the sodium ion ternary positive electrode material, a lithium source and a ternary precursor so as to prepare a lithium-sodium composite ternary positive electrode material with coexistence of P2 phase and O3 phase, and then performing coating modification to obtain the coated lithium-sodium composite ternary positive electrode material. The coated lithium-sodium composite ternary positive electrode material of the present application has excellent electrochemical properties.

Description

一种包覆型锂钠复合三元正极材料及其制备方法A coated lithium sodium composite ternary positive electrode material and preparation method thereof 技术领域Technical Field
本申请涉及锂离子正极材料技术领域，尤其是一种包覆型锂钠复合三元正极材料及其制备方法。The present application relates to the technical field of lithium-ion positive electrode materials, and in particular to a coated lithium-sodium composite ternary positive electrode material and a preparation method thereof.
背景技术Background Art
近年来，化石能源价格上涨和燃烧造成的环境污染等问题，使得越来越多的国家大力发展新型清洁能源，主要是发展以锂离子电池为主的新能源技术，鼓励新能源汽车发展。随着新能源汽车销量的快速增长，对主要原材料锂的需求也随之增加，使得锂资源相对稀缺的问题进一步暴露，同时，电池级碳酸锂的高成本也限制了新能源技术的进一步发展。In recent years, the rising prices of fossil energy and environmental pollution caused by burning have led more and more countries to vigorously develop new clean energy, mainly new energy technologies based on lithium-ion batteries, and encourage the development of new energy vehicles. With the rapid growth of new energy vehicle sales, the demand for lithium, the main raw material, has also increased, further exposing the problem of relative scarcity of lithium resources. At the same time, the high cost of battery-grade lithium carbonate has also restricted the further development of new energy technologies.
为了能够降低新能源电池的成本，促进新能源技术快速发展，价格更低、储量更加丰富、分布更加均匀的钠元素越来越受到重视。锂钠两种元素性质相近，标准电极电势相差0.3V，电化学机理相似，很多结构类似的电极材料可以同时适用于钠离子和锂离子电池，因此可以利用钠部分替代锂离子电池中的锂，不仅可以降低成本，而且钠离子特有的性质也能提高锂离子电池的性能。In order to reduce the cost of new energy batteries and promote the rapid development of new energy technologies, sodium, which has a lower price, more abundant reserves and more uniform distribution, has received more and more attention. Lithium and sodium have similar properties, with a standard electrode potential difference of 0.3V and similar electrochemical mechanisms. Many electrode materials with similar structures can be used in both sodium ion and lithium ion batteries. Therefore, sodium can be used to partially replace lithium in lithium ion batteries, which can not only reduce costs, but also improve the performance of lithium ion batteries due to the unique properties of sodium ions.
钠离子电池结构主要分为P2相和O3相，O3相中钠以八面体的形式存在，容量高，但容易发生相变，导致材料结构不稳定，而在P2相中，钠以三棱柱的形式存在，在这个结构中离子扩散速率快，而且晶体结构稳定，能够提高电池的循环和倍率性能。当前对于利用钠替代锂离子电池中部分锂的研究中，主要是利用掺杂的方式使钠进入晶体结构中改善锂离子电池的部分性能。与传统的LiCoO2及LiFePO4材料相比，三元正极材料由于其高容量和低成本等优势而成为最具发展前景的正极材料之一。因此，制备锂钠复合三元正极材料是目前锂离子电池的研究方向之一。The structure of sodium ion batteries is mainly divided into P2 phase and O3 phase. In the O3 phase, sodium exists in the form of octahedron, which has high capacity, but is prone to phase change, resulting in unstable material structure. In the P2 phase, sodium exists in the form of triangular prisms. In this structure, the ion diffusion rate is fast and the crystal structure is stable, which can improve the battery's cycle and rate performance. In the current research on the use of sodium to replace part of the lithium in lithium-ion batteries, the main method is to use doping to make sodium enter the crystal structure to improve some of the performance of lithium-ion batteries. Compared with traditional LiCoO2 and LiFePO4 materials, ternary positive electrode materials have become one of the most promising positive electrode materials due to their advantages such as high capacity and low cost. Therefore, the preparation of lithium-sodium composite ternary positive electrode materials is one of the current research directions of lithium-ion batteries.
相关技术公开了一种钠离子电池正极材料的制备方法，包括制备氢氧化物前驱体NiaMnbMc(OH)2，然后将锂源、钠源与氢氧化物前驱体混合均匀后进行固相烧结，得到NaxLiyNiaMnbMcO2正极材料，其中0.44≤x≤1，该正极材料具有一定的P2、O3相。但是Na占比过多，对锂离子电池正极材料而言，钠掺杂量过 高会导致材料性能衰减；并且该方法制得的正极材料中P2、O3相不均衡，也影响了正极材料的电化学性能不够好。Related art discloses a method for preparing a positive electrode material for a sodium ion battery, comprising preparing a hydroxide precursor Ni a Mn b Mc (OH) 2 , then mixing a lithium source, a sodium source and the hydroxide precursor evenly and then solid-phase sintering them to obtain a Na x Li y Ni a Mn b McO 2 positive electrode material, wherein 0.44 ≤ x ≤ 1, and the positive electrode material has certain P2 and O3 phases. However, Na accounts for too much, and for lithium ion battery positive electrode materials, the sodium doping amount is too high. High concentrations will lead to material performance degradation; and the imbalance of P2 and O3 phases in the positive electrode material prepared by this method also affects the electrochemical performance of the positive electrode material.
因此，需要提供一种电化学性能优异的锂钠复合三元正极材料。Therefore, it is necessary to provide a lithium-sodium composite ternary positive electrode material with excellent electrochemical performance.
发明内容Summary of the invention
本申请的目的在于，克服现有技术中电化学性能较差的缺陷，提供一种包覆型锂钠复合三元正极材料的制备方法，先制备主晶相为P2相的钠离子三元正极材料，然后取钠离子三元正极材料、锂前驱体和三元前驱体再次混合烧结，制备得到P2和O3共存的锂钠复合三元正极材料，再进行包覆改性，即得到包覆型锂钠复合三元正极材料，本申请的包覆型锂钠复合三元正极材料具有优异的电化学性能。The purpose of the present application is to overcome the defects of poor electrochemical performance in the prior art and provide a method for preparing a coated lithium-sodium composite ternary positive electrode material. First, a sodium ion ternary positive electrode material whose main crystal phase is a P2 phase is prepared, and then the sodium ion ternary positive electrode material, a lithium precursor and a ternary precursor are mixed and sintered again to prepare a lithium-sodium composite ternary positive electrode material in which P2 and O3 coexist, and then a coating modification is performed to obtain a coated lithium-sodium composite ternary positive electrode material. The coated lithium-sodium composite ternary positive electrode material of the present application has excellent electrochemical properties.
本申请的另一目的在于提供上述制备方法制得的包覆型锂钠复合三元正极材料。Another object of the present application is to provide a coated lithium-sodium composite ternary positive electrode material prepared by the above preparation method.
为实现上述目的，本申请采用如下技术方案：To achieve the above purpose, this application adopts the following technical solutions:
一种包覆型锂钠复合三元正极材料，通式为：NaxLi0.9(NiyCozMn1-y-z)O2@A，其中x为0.027～0.1，y＝0.55～0.8，z＝0.02～0.05，A为包覆元素的氧化物，所述包覆元素为Ti、B、Co、Al、W、Zr、Sr中至少一种。A coated lithium-sodium composite ternary positive electrode material has the general formula: NaxLi0.9 ( NiyCozMn1 -yz ) O2 @A, wherein x is 0.027-0.1, y is 0.55-0.8, z is 0.02-0.05, A is an oxide of a coating element, and the coating element is at least one of Ti, B, Co, Al, W, Zr and Sr.
优选地，所述包覆型锂钠复合三元正极材料的形貌为球形或类球形颗粒，均粒径为2～5μm。Preferably, the coated lithium-sodium composite ternary positive electrode material has a morphology of spherical or quasi-spherical particles with an average particle size of 2 to 5 μm.
本申请还保护上述包覆型锂钠复合三元正极材料的制备方法，包括如下步骤：The present application also protects a method for preparing the above-mentioned coated lithium-sodium composite ternary positive electrode material, comprising the following steps:
S1.称取钠源和NiyCozMn1-y-z(OH)2三元前驱体，混合后进行第一次烧结，得到钠离子三元正极材料(Nam(NiyCozMn1-y-z)O2)；S1. Weigh a sodium source and a Ni y Co z Mn 1-yz (OH) 2 ternary precursor, mix them, and then sinter them for the first time to obtain a sodium ion ternary positive electrode material (Na m (Ni y Co z Mn 1-yz )O 2 );
S2.将步骤S1得到的钠离子三元正极材料、锂源和NiyCozMn1-y-z(OH)2三元前驱体混合后进行第二次烧结，得到锂钠复合三元正极材料(NaxLi0.9(NiyCozMn1-y-z)O2)，其中，钠离子三元正极材料∶锂源中的锂∶(NiyCozMn1-y-z(OH)2三元前驱体中Ni、Co、Mn元素总摩尔量)的摩尔比为(0.08～0.18)∶0.9∶0.9，且锂源在此基础上过量5～8wt.％；S2. The sodium ion ternary positive electrode material, the lithium source and the Ni y Co z Mn 1-yz (OH) 2 ternary precursor obtained in step S1 are mixed and sintered for a second time to obtain a lithium-sodium composite ternary positive electrode material (Na x Li 0.9 (Ni y Co z Mn 1-yz )O 2 ), wherein the molar ratio of the sodium ion ternary positive electrode material: the lithium in the lithium source: (the total molar amount of Ni, Co and Mn elements in the Ni y Co z Mn 1-yz (OH) 2 ternary precursor) is (0.08-0.18): 0.9: 0.9, and the lithium source is in excess of 5-8 wt.% on this basis;
S3.将包覆剂与所述锂钠复合三元正极材料混合，进行第三次烧结，得到包覆型锂钠复合三元正极材料(NaxLi0.9(NiyCozMn1-y-z)O2@A)。 S3. Mixing the coating agent with the lithium sodium composite ternary positive electrode material, and performing a third sintering to obtain a coated lithium sodium composite ternary positive electrode material (Na x Li 0.9 (Ni y Co z Mn 1-yz )O 2 @A).
本申请的制备方法通过制备主晶相为P2相的钠离子三元正极材料，然后将钠离子三元正极材料、锂源和NiyCozMn1-y-z(OH)2三元前驱体再次混合烧结，制备得到P2和O3相共存的锂钠复合三元正极材料，再进行包覆改性，即得到包覆型锂钠复合三元正极材料。The preparation method of the present application prepares a sodium ion ternary positive electrode material whose main crystal phase is the P2 phase, and then mixes and sinters the sodium ion ternary positive electrode material, a lithium source and a Ni y Co z Mn 1-yz (OH) 2 ternary precursor again to obtain a lithium-sodium composite ternary positive electrode material in which P2 and O3 phases coexist, and then performs coating modification to obtain a coated lithium-sodium composite ternary positive electrode material.
通过上述制备方法制得的包覆型锂钠复合三元正极材料，具有共存的P2相和O3相，且两相含量适宜；Na以较低量掺杂，一方面降低了材料的成本，另一方面改善正极材料的电化学性能；表面包覆剂减少了电解液对锂钠复合正极材料的腐蚀的作用，进一步改善了锂钠复合三元正极材料的循环性能。The coated lithium-sodium composite ternary positive electrode material prepared by the preparation method has coexisting P2 phase and O3 phase, and the content of the two phases is appropriate; Na is doped in a relatively low amount, which reduces the cost of the material on the one hand, and improves the electrochemical properties of the positive electrode material on the other hand; the surface coating agent reduces the corrosion effect of the electrolyte on the lithium-sodium composite positive electrode material, and further improves the cycle performance of the lithium-sodium composite ternary positive electrode material.
发明人研究发现，步骤S1中制得的钠离子三元正极材料的主晶相为由Na+形成的P2相，再经步骤S2的混合烧结，由Li+形成一定量的O3相，可以实现锂钠复合三元正极材料中P2相和O3相以适宜比例的共存，提高了离子扩散速率，使晶体结构稳定，能够提高电池的循环和倍率性能，从而提升电化学性能。同时，本申请中通过控制步骤S2中的各组分配比，使得钠元素的掺杂量在0.1以下，实现了既不会由钠掺杂量过高而导致材料性能衰减，又保证了P2相含量适宜，从而起到稳定材料晶体结构的作用。The inventors have found that the main crystal phase of the sodium ion ternary positive electrode material prepared in step S1 is a P2 phase formed by Na + , and then after mixed sintering in step S2, a certain amount of O3 phase is formed by Li + , which can achieve the coexistence of P2 phase and O3 phase in a suitable ratio in the lithium-sodium composite ternary positive electrode material, improve the ion diffusion rate, stabilize the crystal structure, and improve the cycle and rate performance of the battery, thereby improving the electrochemical performance. At the same time, in this application, by controlling the distribution ratio of each group in step S2, the doping amount of the sodium element is below 0.1, which achieves that the material performance will not be attenuated due to excessive sodium doping, and ensures that the P2 phase content is appropriate, thereby playing a role in stabilizing the crystal structure of the material.
优选地，步骤S1中，所述钠源和NiyCozMn1-y-z(OH)2三元前驱体的称取量按照钠源中的钠∶(NiyCozMn1-y-z(OH)2三元前驱体中Ni、Co、Mn元素总摩尔量)的摩尔比为(0.27～1)∶1，且钠源在此基础上过量1～5wt.％进行称取。Preferably, in step S1, the weighed amounts of the sodium source and the Ni y Co z Mn 1-yz (OH) 2 ternary precursor are according to a molar ratio of sodium in the sodium source: (total molar amount of Ni, Co and Mn elements in the Ni y Co z Mn 1-yz (OH) 2 ternary precursor) of (0.27-1):1, and the sodium source is weighed in an excess of 1-5 wt.% on this basis.
优选地，所述NiyCozMn1-y-z(OH)2三元前驱体中y＝0.55～0.8，z＝0.02～0.05。Preferably, in the Ni y Co z Mn 1-yz (OH) 2 ternary precursor, y=0.55-0.8, z=0.02-0.05.
Ni、Co、Mn作为过渡金属，在适宜的比例下有助于正极材料的电化学性能更优。Ni, Co, and Mn, as transition metals, contribute to better electrochemical performance of the positive electrode material in appropriate proportions.
优选地，所述钠源为碳酸钠、氢氧化钠、硝酸钠、氯化钠中的至少一种。Preferably, the sodium source is at least one of sodium carbonate, sodium hydroxide, sodium nitrate and sodium chloride.
优选地，所述锂源为碳酸锂、氢氧化锂、硝酸锂、氯化锂中的至少一种。Preferably, the lithium source is at least one of lithium carbonate, lithium hydroxide, lithium nitrate and lithium chloride.
所述包覆剂为含有包覆元素的化合物，所述包覆元素为Ti、B、Co、Al、W、Zr、Sr中至少一种。The coating agent is a compound containing a coating element, and the coating element is at least one of Ti, B, Co, Al, W, Zr, and Sr.
优选地，所述包覆元素为Ti、Co、B中至少一种。Preferably, the coating element is at least one of Ti, Co and B.
可选地，所述化合物可以为氧化物、氢氧化物或酸。Alternatively, the compound may be an oxide, a hydroxide or an acid.
可选地，含有Ti的化合物为TiO2，含有B的化合物为H3BO3，含有Co的化合物为CoOOH。Optionally, the compound containing Ti is TiO 2 , the compound containing B is H 3 BO 3 , and the compound containing Co is CoOOH.
发明人研究发现，包覆剂的种类对于包覆型锂钠复合三元正极材料的电化 学性能有重要影响。包覆剂可以实现减少电解液对锂钠复合正极材料的腐蚀，从而改善了锂钠复合三元正极材料的循环性能。在多种包覆剂中，Ti、Co、B元素对锂钠复合三元正极材料的腐蚀改善效果相对更优，特别是使用含有B和Ti元素的包覆剂制得的包覆型锂钠复合三元正极材料的循环性能优异。The inventors found that the type of coating agent has an important influence on the electrochemical properties of the coated lithium-sodium composite ternary cathode material. The coating agent can reduce the corrosion of the electrolyte on the lithium-sodium composite positive electrode material, thereby improving the cycle performance of the lithium-sodium composite ternary positive electrode material. Among various coating agents, Ti, Co, and B elements have a relatively better effect on the corrosion improvement of lithium-sodium composite ternary positive electrode materials, especially the coated lithium-sodium composite ternary positive electrode material prepared by the coating agent containing B and Ti elements has excellent cycle performance.
优选地，步骤S2中，钠离子三元正极材料∶锂源中的锂∶(NiyCozMn1-y-z(OH)2三元前驱体中Ni、Co、Mn元素总摩尔量)的摩尔比为0.1∶0.9∶0.9，且锂源在此基础上过量5～8wt.％。Preferably, in step S2, the molar ratio of sodium ion ternary positive electrode material: lithium in the lithium source: (total molar amount of Ni, Co and Mn elements in Ni y Co z Mn 1-y z (OH) 2 ternary precursor) is 0.1:0.9:0.9, and the lithium source is in excess of 5-8 wt.%.
步骤S3中，按照包覆元素的重量占锂钠复合三元正极材料的0.2～0.7wt.％的重量比例称取、添加包覆剂。In step S3, a coating agent is weighed and added according to a weight ratio of 0.2 to 0.7 wt.% of the weight of the coating element to the lithium-sodium composite ternary positive electrode material.
步骤S3中，经过混合、烧结，最终包覆在锂钠复合三元正极材料表面的包覆材料为含有包覆元素的氧化物，因此，包覆剂的添加量以包覆元素的重量关系进行计算、称取。发明人研究发现，包覆元素的重量占锂钠复合三元正极材料的0.2～0.7wt.％时，既可以实现良好的包覆改性效果，使得包覆型锂钠复合三元正极材料的循环性能更优，又不会过多包覆从而影响锂钠复合三元正极材料的电性能发挥。In step S3, after mixing and sintering, the coating material finally coated on the surface of the lithium-sodium composite ternary positive electrode material is an oxide containing a coating element. Therefore, the amount of coating agent added is calculated and weighed according to the weight relationship of the coating element. The inventors have found that when the weight of the coating element accounts for 0.2-0.7wt.% of the lithium-sodium composite ternary positive electrode material, a good coating modification effect can be achieved, making the cycle performance of the coated lithium-sodium composite ternary positive electrode material better, and the excessive coating will not affect the electrical performance of the lithium-sodium composite ternary positive electrode material.
优选地，步骤S1中，所述第一次烧结的条件为在流量4～10m3/h的空气气氛下，以3～5℃/min升温速率，加热至750～850℃烧结15～24h。Preferably, in step S1, the first sintering condition is to heat to 750-850°C and sinter for 15-24h at a heating rate of 3-5°C/min in an air atmosphere with a flow rate of 4-10m3 /h.
优选地，步骤S2中，所述第二次烧结的条件为在流量4～10m3/h的空气气氛下，以3～5℃/min升温速率加热至700～800℃保温2～4h，再以2～5℃/min升温速率加热至850～950℃烧结10～15h。Preferably, in step S2, the second sintering conditions are: heating to 700-800°C at a heating rate of 3-5°C/min for 2-4h in an air atmosphere with a flow rate of 4-10m3 /h, and then heating to 850-950°C at a heating rate of 2-5°C/min for 10-15h.
优选地，步骤S3中，所述第三次烧结的条件为以2～5℃/min升温速率加热至300～700℃烧结4～8h。Preferably, in step S3, the third sintering condition is to heat to 300-700° C. at a heating rate of 2-5° C./min and sinter for 4-8 hours.
与现有技术相比，本申请的有益效果是：Compared with the prior art, the beneficial effects of this application are:
本申请开发了一种包覆型锂钠复合三元正极材料及其制备方法。通过先制备主晶相为P2相的钠离子三元正极材料，然后取钠离子三元正极材料、锂前驱体和三元前驱体再次混合烧结，制备得到P2和O3相共存的锂钠复合三元正极材料，再进行包覆改性，得到包覆型锂钠复合三元正极材料。本申请的包覆型锂钠复合三元正极材料中锂的化学计量比由1降低至0.9，有效降低了成本，且包覆型锂钠复合三元正极材料具有优异的电化学性能。 The present application develops a coated lithium-sodium composite ternary positive electrode material and a preparation method thereof. A sodium ion ternary positive electrode material whose main crystal phase is the P2 phase is first prepared, and then the sodium ion ternary positive electrode material, the lithium precursor and the ternary precursor are mixed and sintered again to prepare a lithium-sodium composite ternary positive electrode material in which P2 and O3 phases coexist, and then the coated modification is performed to obtain a coated lithium-sodium composite ternary positive electrode material. The stoichiometric ratio of lithium in the coated lithium-sodium composite ternary positive electrode material of the present application is reduced from 1 to 0.9, which effectively reduces the cost, and the coated lithium-sodium composite ternary positive electrode material has excellent electrochemical properties.
附图说明BRIEF DESCRIPTION OF THE DRAWINGS
图1为实施例1制备的包覆型锂钠复合三元正极材料的SEM图。FIG. 1 is a SEM image of the coated lithium-sodium composite ternary positive electrode material prepared in Example 1.
图2为实施例3和对比例1制备的包覆型锂钠复合三元正极材料的XRD图。FIG. 2 is an XRD diagram of the coated lithium-sodium composite ternary positive electrode materials prepared in Example 3 and Comparative Example 1.
具体实施方式DETAILED DESCRIPTION
为更好的说明本申请的目的、技术方案和优点，下面将结合具体实施例来进一步说明本申请，但实施例并不对本申请做任何形式的限定。除非特别说明，本申请采用的试剂、方法和设备为本技术领域常规试剂、方法和设备。除非特别说明，本申请所用试剂和材料均为市购。In order to better illustrate the purpose, technical scheme and advantages of the present application, the present application will be further described below in conjunction with specific embodiments, but the embodiments do not limit the present application in any form. Unless otherwise specified, the reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the art. Unless otherwise specified, the reagents and materials used in the present application are commercially available.
实施例1Example 1
实施例1提供一种包覆型锂钠复合三元正极材料，制备方法如下：Example 1 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is as follows:
S1.按照Na/Me(Me为过渡金属Ni+Co+Mn)摩尔比为0.9:1称取钠源(碳酸钠)和三元前驱体(Ni0.53Co0.02Mn0.45(OH)2)，碳酸钠质量在此基础上过量5wt％；S1. Weigh a sodium source (sodium carbonate) and a ternary precursor (Ni 0.53 Co 0.02 Mn 0.45 (OH) 2 ) according to a Na/Me (Me is transition metal Ni+Co+Mn) molar ratio of 0.9:1, with an excess of 5wt% of sodium carbonate;
将钠源和三元前驱体(Ni0.53Co0.02Mn0.45(OH)2)在高混机内混合均匀后，置入箱式炉内，在流量4m3/h的空气气氛下以3℃/min升温速率加热至750℃烧结24h；烧结结束后随炉冷却至200℃以下，过300目筛网，即得到钠离子三元正极材料(Na0.9(Ni0.53Co0.02Mn0.45)O2)，主晶相为P2相；The sodium source and the ternary precursor (Ni 0.53 Co 0.02 Mn 0.45 (OH) 2 ) were mixed uniformly in a high-speed mixer, placed in a box furnace, heated to 750° C. at a heating rate of 3° C./min in an air atmosphere with a flow rate of 4 m 3 /h, and sintered for 24 hours; after sintering, the mixture was cooled to below 200° C. in the furnace, and passed through a 300-mesh sieve to obtain a sodium ion ternary positive electrode material (Na 0.9 (Ni 0.53 Co 0.02 Mn 0.45 )O 2 ), the main crystal phase of which was the P2 phase;
S2.按照Na0.9(Ni0.53Co0.02Mn0.45)O2：Li：Me摩尔比0.1:0.9:0.9称取步骤S1制备的Na0.9(Ni0.53Co0.02Mn0.45)O2、锂源(氢氧化锂)和三元前驱体(Ni0.53Co0.02Mn0.45(OH)2)，锂源质量在此基础上过量7wt％；S2. weigh Na 0.9 (Ni 0.53 Co 0.02 Mn 0.45 )O 2 , a lithium source (lithium hydroxide) and a ternary precursor (Ni 0.53 Co 0.02 Mn 0.45 (OH) 2 ) prepared in step S1 according to a Na 0.9 (Ni 0.53 Co 0.02 Mn 0.45 )O 2 :Li:Me molar ratio of 0.1:0.9:0.9, with the mass of the lithium source being in excess of 7wt%;
原料在高混机内混合均匀后，置入箱式炉内，在流量10m3/h的空气气氛下以3℃/min升温速率加热至800℃保温2h，然后再以2℃/min升温速率加热至850℃烧结15h；After the raw materials are mixed evenly in a high-speed mixer, they are placed in a box furnace and heated to 800°C at a heating rate of 3°C/min in an air atmosphere with a flow rate of 10m 3 /h and kept at that temperature for 2h. Then, they are heated to 850°C at a heating rate of 2°C/min and sintered for 15h.
烧结结束后随炉冷却至200℃以下，将样品过300目筛网，即得到锂钠复合三元正极材料(Na0.09Li0.9(Ni0.53Co0.02Mn0.45)O2)，晶相为P2和O3共存；After sintering, the sample was cooled to below 200°C in the furnace and passed through a 300-mesh sieve to obtain a lithium-sodium composite ternary cathode material (Na 0.09 Li 0.9 (Ni 0.53 Co 0.02 Mn 0.45 )O 2 ), with a crystal phase of coexistence of P2 and O3.
S3.按照B的重量占锂钠复合三元正极材料的0.5wt.％的重量比例称取、添加包覆剂(H3BO3)，利用球磨机将制备得到的锂钠复合三元正极材料与包覆剂混合均匀，以2℃/min升温速率加热至550℃烧结6h；S3. Weigh and add a coating agent (H 3 BO 3 ) according to the weight ratio of B to 0.5 wt.% of the lithium-sodium composite ternary cathode material, mix the prepared lithium-sodium composite ternary cathode material and the coating agent evenly using a ball mill, heat to 550° C. at a heating rate of 2° C./min and sinter for 6 h;
烧结结束后随炉冷却至200℃以下，将样品过300目筛网，即得到最终包覆型锂钠复合三元正极材料(Na0.09Li0.9(Ni0.53Co0.02Mn0.45)O2@B2O3)。 After sintering, the sample was cooled to below 200°C in the furnace, and passed through a 300-mesh sieve to obtain the final coated lithium-sodium composite ternary positive electrode material (Na 0.09 Li 0.9 (Ni 0.53 Co 0.02 Mn 0.45 )O 2 @B 2 O 3 ).
实施例2Example 2
实施例2提供一种包覆型锂钠复合三元正极材料，制备方法与实施例1的区别在于：Example 2 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
步骤S3中按照Ti的重量占锂钠复合三元正极材料的0.5wt.％的重量比例称取、添加包覆剂TiO2。In step S3, coating agent TiO 2 is weighed and added according to a weight ratio of Ti to 0.5 wt.% of the lithium-sodium composite ternary positive electrode material.
实施例3Example 3
实施例3提供一种包覆型锂钠复合三元正极材料，制备方法与实施例1的区别在于：Example 3 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
步骤S3中按照Co的重量占锂钠复合三元正极材料的0.5wt.％的重量比例称取、添加包覆剂CoOOH。In step S3, the coating agent CoOOH is weighed and added according to a weight ratio of 0.5 wt.% of the weight of Co to the lithium-sodium composite ternary positive electrode material.
实施例4Example 4
实施例4提供一种包覆型锂钠复合三元正极材料，制备方法与实施例1的区别在于：Example 4 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
步骤S3中，按照B的重量占锂钠复合三元正极材料的0.2wt.％的重量比例称取添加H3BO3，Ti的重量占锂钠复合三元正极材料的0.3wt.％的重量比例称取添加TiO2；H3BO3和TiO2混合作为包覆剂。In step S3, H 3 BO 3 is added according to a weight ratio of 0.2 wt.% of B to the lithium-sodium composite ternary positive electrode material, and TiO 2 is added according to a weight ratio of 0.3 wt.% of Ti to the lithium-sodium composite ternary positive electrode material; H 3 BO 3 and TiO 2 are mixed as coating agents.
实施例5Example 5
实施例5提供一种包覆型锂钠复合三元正极材料，制备方法与实施例1的区别在于：Example 5 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
步骤S1中Na/Me的摩尔比为0.8:1。The molar ratio of Na/Me in step S1 is 0.8:1.
实施例6Example 6
实施例6提供一种包覆型锂钠复合三元正极材料，制备方法与实施例1的区别在于：Example 6 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
步骤S1中Na/Me的摩尔比为0.5:1。The molar ratio of Na/Me in step S1 is 0.5:1.
实施例7Example 7
实施例7提供一种包覆型锂钠复合三元正极材料，制备方法与实施例1的区别在于： Example 7 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
步骤S1中Na/Me的摩尔比为0.27:1。The molar ratio of Na/Me in step S1 is 0.27:1.
实施例8Example 8
实施例8提供一种包覆型锂钠复合三元正极材料，制备方法与实施例1的区别在于：Example 8 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
其中三元前驱体Ni0.53Co0.02Mn0.45(OH)2替换为Ni0.60Co0.05Mn0.35(OH)2。The ternary precursor Ni 0.53 Co 0.02 Mn 0.45 (OH) 2 was replaced by Ni 0.60 Co 0.05 Mn 0.35 (OH) 2 .
实施例9Example 9
实施例9提供一种包覆型锂钠复合三元正极材料，制备方法与实施例1的区别在于：Example 9 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
其中三元前驱体Ni0.53Co0.02Mn0.45(OH)2替换为Ni0.8Co0.03Mn0.17(OH)2。The ternary precursor Ni 0.53 Co 0.02 Mn 0.45 (OH) 2 was replaced by Ni 0.8 Co 0.03 Mn 0.17 (OH) 2 .
实施例10Example 10
实施例10提供一种包覆型锂钠复合三元正极材料，制备方法与实施例1的区别在于：Example 10 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
步骤S3中B的重量占锂钠复合三元正极材料的0.2wt.％的重量比例称取、添加包覆剂(H3BO3)。In step S3, a coating agent (H 3 BO 3 ) is weighed and added in a weight ratio of 0.2 wt.% of the weight of the lithium-sodium composite ternary positive electrode material.
实施例11Embodiment 11
实施例11提供一种包覆型锂钠复合三元正极材料，制备方法与实施例1的区别在于：Example 11 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
步骤S3中B的重量占锂钠复合三元正极材料的0.7wt.％的重量比例称取、添加包覆剂(H3BO3)。In step S3, a coating agent (H 3 BO 3 ) is weighed and added in a weight ratio of 0.7 wt.% of the weight of the lithium-sodium composite ternary positive electrode material.
实施例12Example 12
实施例12提供一种包覆型锂钠复合三元正极材料，制备方法与实施例1的区别在于：Example 12 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
钠源替换为氢氧化钠，锂源替换为碳酸锂。The sodium source is replaced by sodium hydroxide, and the lithium source is replaced by lithium carbonate.
实施例13Embodiment 13
实施例13提供一种包覆型锂钠复合三元正极材料，制备方法与实施例1的区别在于：Example 13 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
步骤S2中Na0.9(Ni0.53Co0.02Mn0.45)O2：Li：Me摩尔比为0.18:0.9:0.9。 In step S2, the molar ratio of Na 0.9 (Ni 0.53 Co 0.02 Mn 0.45 )O 2 :Li:Me is 0.18:0.9:0.9.
实施例14Embodiment 14
实施例14提供一种包覆型锂钠复合三元正极材料，制备方法与实施例1的区别在于：Example 14 provides a coated lithium-sodium composite ternary positive electrode material, and the preparation method is different from that of Example 1 in that:
步骤S1中，烧结的条件为：在流量10m3/h的空气气氛下以5℃/min升温速率加热至850℃烧结15h；In step S1, the sintering conditions are: heating to 850°C at a heating rate of 5°C/min and sintering for 15h in an air atmosphere with a flow rate of 10m3 /h;
步骤S2中，烧结的条件为：在流量4m3/h的空气气氛下以5℃/min升温速率加热至700℃保温4h，然后再以5℃/min升温速率加热至950℃烧结10h；In step S2, the sintering conditions are: heating to 700°C at a heating rate of 5°C/min and keeping the temperature for 4 hours in an air atmosphere with a flow rate of 4m 3 /h, and then heating to 950°C at a heating rate of 5°C/min and sintering for 10 hours;
步骤S3中，烧结的条件为：以5℃/min升温速率加热至700℃烧结4h。In step S3, the sintering conditions are: heating to 700° C. at a heating rate of 5° C./min and sintering for 4 h.
对比例1Comparative Example 1
对比例1提供一种正极材料，制备方法如下：Comparative Example 1 provides a positive electrode material, and the preparation method is as follows:
按照Na：Li：Me(Me为过渡金属Ni+Co+Mn)摩尔比0.08:0.9:0.9称取碳酸钠、氢氧化锂和前驱体(Ni0.60Co0.05Mn0.35(OH)2)，氢氧化锂质量在此基础上过量7wt.％；Sodium carbonate, lithium hydroxide and precursor (Ni 0.60 Co 0.05 Mn 0.35 (OH) 2 ) were weighed according to the molar ratio of Na:Li:Me (Me is transition metal Ni+Co+Mn) of 0.08:0.9:0.9, and the mass of lithium hydroxide was 7wt.% in excess;
原料在高混机内混合均匀后，置入箱式炉内，在流量6m3/h的空气气氛下以3℃/min升温速率加热至750℃保温2h，然后再以2℃/min升温速率加热至900℃烧结12h；After the raw materials are mixed evenly in a high-speed mixer, they are placed in a box furnace and heated to 750°C at a heating rate of 3°C/min in an air atmosphere with a flow rate of 6m 3 /h for 2 hours, and then heated to 900°C at a heating rate of 2°C/min for sintering for 12 hours;
烧结结束后随炉冷却至200℃以下，将样品过300目筛网，即得到P2和O3相共存的锂钠复合三元正极材料Na0.08Li0.9(Ni0.6Co0.05Mn0.35)O2；After sintering, the sample was cooled to below 200°C in the furnace, and passed through a 300-mesh sieve to obtain a lithium-sodium composite ternary cathode material Na 0.08 Li 0.9 (Ni 0.6 Co 0.05 Mn 0.35 )O 2 in which P2 and O3 phases coexisted.
按照B的重量占锂钠复合三元正极材料的0.5wt.％称取包覆剂H3BO3，利用球磨机将制备得到的锂钠复合三元正极材料与包覆剂混合均匀，以2℃/min升温速率加热至550℃烧结6h。The coating agent H 3 BO 3 was weighed according to the weight of B accounting for 0.5 wt.% of the lithium-sodium composite ternary positive electrode material, and the prepared lithium-sodium composite ternary positive electrode material and the coating agent were mixed evenly by a ball mill, and heated to 550° C. at a heating rate of 2° C./min and sintered for 6 h.
即对比例1是未经两步烧结，而是一次烧结得到P2相和O3相共存的锂钠复合三元正极材料，再进行包覆。That is, in Comparative Example 1, instead of two-step sintering, a lithium-sodium composite ternary positive electrode material in which P2 phase and O3 phase coexist is obtained by sintering once, and then coating is performed.
对比例2Comparative Example 2
对比例2提供一种正极材料，制备方法如下：Comparative Example 2 provides a positive electrode material, and the preparation method is as follows:
将氢氧化锂和前驱体(Ni0.60Co0.05Mn0.35(OH)2)按照Li：Me(Me为过渡金属Ni+Co+Mn)摩尔比1:1称取，氢氧化锂质量在此基础上过量7wt％；Lithium hydroxide and a precursor (Ni 0.60 Co 0.05 Mn 0.35 (OH) 2 ) were weighed in a Li:Me (Me is transition metal Ni+Co+Mn) molar ratio of 1:1, and the mass of lithium hydroxide was 7wt% in excess;
原料在高混机内混合均匀后，置入箱式炉内，在流量6m3/h的空气气氛下以3℃/min升温速率加热至750℃保温2h，然后再以2℃/min升温速率加热至940℃ 烧结12h；After the raw materials are mixed evenly in the high-speed mixer, they are placed in a box furnace and heated to 750℃ at a heating rate of 3℃/min in an air atmosphere with a flow rate of 6m3 /h. They are kept at this temperature for 2h and then heated to 940℃ at a heating rate of 2℃/min. Sintering for 12 hours;
烧结结束后随炉冷却至200℃以下，将样品过300目筛网，即得到三元正极材料Li(Ni0.6Co0.05Mn0.35)O2；After sintering, the sample was cooled to below 200°C in the furnace, and passed through a 300-mesh sieve to obtain the ternary positive electrode material Li(Ni 0.6 Co 0.05 Mn 0.35 )O 2 ;
按照B的重量占三元正极材料的0.5wt％称取包覆剂H3BO3，利用球磨机将制备得到的锂钠复合三元正极材料与包覆剂混合均匀，以2℃/min升温速率加热至700℃烧结4h；烧结结束后随炉冷却至200℃以下，将样品过300目筛网，即得到B包覆的锂复合三元正极材料。The coating agent H 3 BO 3 was weighed according to the weight of B accounting for 0.5wt% of the ternary positive electrode material, and the prepared lithium sodium composite ternary positive electrode material and the coating agent were mixed evenly by a ball mill, and heated to 700°C at a heating rate of 2°C/min and sintered for 4h; after the sintering, the furnace was cooled to below 200°C, and the sample was passed through a 300-mesh sieve to obtain the B-coated lithium composite ternary positive electrode material.
即对比例2是未经钠掺杂，不含P2相。That is, Comparative Example 2 is not doped with sodium and does not contain the P2 phase.
对比例3Comparative Example 3
对比例3提供一种正极材料，制备方法与实施例1的区别在于：Comparative Example 3 provides a positive electrode material, and the preparation method is different from that of Example 1 in that:
步骤S1中Na/Me的摩尔比为0.1:1。The molar ratio of Na/Me in step S1 is 0.1:1.
对比例4Comparative Example 4
对比例4提供一种正极材料，制备方法与实施例1的区别在于：Comparative Example 4 provides a positive electrode material, and the preparation method is different from that of Example 1 in that:
步骤S2中Na0.9(Ni0.53Co0.02Mn0.45)O2：Li：Me摩尔比为0.2:0.9:0.9。In step S2, the molar ratio of Na 0.9 (Ni 0.53 Co 0.02 Mn 0.45 )O 2 :Li:Me is 0.2:0.9:0.9.
对比例5Comparative Example 5
对比例5提供一种正极材料，制备方法与实施例1的区别在于：Comparative Example 5 provides a positive electrode material, and the preparation method is different from that of Example 1 in that:
不进行步骤S3，即不进行包覆改性。Step S3 is not performed, that is, coating modification is not performed.
性能测试Performance Testing
对上述实施例和对比例所制得的正极材料进行性能测试，具体方法如下：The performance test of the positive electrode materials prepared in the above embodiments and comparative examples is carried out as follows:
利用涂覆法制备电极片；铝箔为集流体，测试电池的正电极组分由正极材料、导电剂乙快黑、粘结剂聚四氧乙烯按照质量比9:0.5:0.5的混合调浆，均匀搅拌混合浆料45分钟以上，将混合浆料均匀地涂抹在铝箔集流体上；110℃鼓风干燥后，裁剪成直径约1.4cm的圆片，随后将裁剪后的电极片置于105℃真空干燥4h，即得到测试电池的正极片；以金属锂片为负极，采用常规商用电解液和隔膜，将正负极组装后制成扣式测试电池，检测首次库仑效率、首次充放电比容量、1C循环50次放电容量保持率。The electrode sheet was prepared by a coating method; aluminum foil was used as the current collector, and the positive electrode component of the test battery was mixed with a positive electrode material, a conductive agent, and a binder, polytetraoxyethylene, in a mass ratio of 9:0.5:0.5. The mixed slurry was evenly stirred for more than 45 minutes, and the mixed slurry was evenly applied to the aluminum foil current collector; after being dried with air at 110°C, it was cut into discs with a diameter of about 1.4 cm, and then the cut electrode sheets were placed in a vacuum dryer at 105°C for 4 hours to obtain the positive electrode sheet of the test battery; a metal lithium sheet was used as the negative electrode, and conventional commercial electrolytes and separators were used to assemble the positive and negative electrodes into a button-type test battery, and the first coulombic efficiency, the first charge and discharge specific capacity, and the discharge capacity retention rate of 50 cycles at 1C were tested.
SEM检测方法：采用扫描电子显微镜对样品形貌进行观察。SEM detection method: Use scanning electron microscope to observe the sample morphology.
XRD检测方法：利用X射线衍射分析仪，使用Cu靶Kα射线，扫描范围为 10～90°。XRD detection method: using X-ray diffraction analyzer, using Cu target Kα radiation, the scanning range is 10～90°.
图1为实施例1制备的包覆型锂钠复合三元正极材料的SEM图。图2为实施例3和对比例1制备的包覆型锂钠复合三元正极材料的XRD图。Figure 1 is a SEM image of the coated lithium sodium composite ternary positive electrode material prepared in Example 1. Figure 2 is an XRD image of the coated lithium sodium composite ternary positive electrode material prepared in Example 3 and Comparative Example 1.
根据图2，可以看出，实施例3所制备的包覆型锂钠复合三元正极材料的XRD衍射图谱中出现了P2相的特征峰(002)和(004)晶面，这表明制备的材料中存在一定量的P2相。对比例1中直接将钠源、锂源和前驱体混合烧结得到的材料中P2相的特征峰(002)和(004)较小，这也表明对比例1中得到的P2相较实施例3中更少。According to Figure 2, it can be seen that the characteristic peaks (002) and (004) of the P2 phase appear in the XRD diffraction pattern of the coated lithium-sodium composite ternary positive electrode material prepared in Example 3, which indicates that a certain amount of P2 phase exists in the prepared material. The characteristic peaks (002) and (004) of the P2 phase in the material obtained by directly mixing and sintering the sodium source, lithium source and precursor in Comparative Example 1 are smaller, which also indicates that the P2 phase obtained in Comparative Example 1 is less than that in Example 3.
实施例和对比例的电化学性能测试结果见表1。The electrochemical performance test results of the embodiments and comparative examples are shown in Table 1.
表1

Table 1

根据上表的测试结果，电化学性能测试结果，本申请的各实施例所制备的正极材料均具有良好的电化学性能，首次库伦效率≥85.2％，首次充电比容量在194.8～230.1mAh/g，首次放电比容量在170.1～206.8mAh/g，1C循环50次放电容量保持率≥81.2％。According to the test results and electrochemical performance test results in the above table, the positive electrode materials prepared in each embodiment of the present application have good electrochemical performance, with a first coulombic efficiency ≥85.2%, a first charge specific capacity of 194.8 to 230.1 mAh/g, a first discharge specific capacity of 170.1 to 206.8 mAh/g, and a discharge capacity retention rate of ≥81.2% after 50 cycles at 1C.
对比例1中未经两步烧结，而是一次烧结得到P2相和O3相共存的锂钠复合三元正极材料，再进行包覆。仅由一次烧结会导致正极材料中P2相含量较低，且影响材料的电化学性能。对比例1与实施例8相比，电化学性能劣化。In Comparative Example 1, instead of two-step sintering, a lithium-sodium composite ternary positive electrode material in which P2 phase and O3 phase coexist is obtained by sintering once, and then coating is performed. Sintering once alone will result in a lower content of P2 phase in the positive electrode material and affect the electrochemical performance of the material. Compared with Example 8, the electrochemical performance of Comparative Example 1 is deteriorated.
对比例2中未经钠掺杂，不含P2相，制得的正极材料的1C循环50次放电容量保持率较低。In Comparative Example 2, there is no sodium doping and no P2 phase is contained, and the discharge capacity retention rate of the prepared positive electrode material after 50 1C cycles is low.
对比例3中钠掺杂量过低，形成的P2相占比过少，制得的正极材料的循环新相对较差；对比例4中钠掺杂量过高，对锂离子电池正极材料而言，钠掺杂量过高会导致材料性能衰减。In Comparative Example 3, the sodium doping amount is too low, the proportion of the formed P2 phase is too small, and the cycle life of the obtained positive electrode material is relatively poor; in Comparative Example 4, the sodium doping amount is too high. For lithium-ion battery positive electrode materials, too high sodium doping amount will lead to material performance degradation.
对比例5为未经包覆的正极材料，可以看出，在不包覆的情况下，由于电解液对锂钠复合正极材料的腐蚀，正极材料的的循环性能较差。Comparative Example 5 is an uncoated positive electrode material. It can be seen that without coating, the cycle performance of the positive electrode material is poor due to the corrosion of the lithium-sodium composite positive electrode material by the electrolyte.
最后所应当说明的是，以上实施例仅用以说明本申请的技术方案而非对本申请保护范围的限制，尽管参照较佳实施例对本申请作了详细说明，本领域的普通技术人员应当理解，可以对本申请的技术方案进行修改或者等同替换，而不脱离本申请技术方案的实质和范围。 Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application rather than to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that the technical solution of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present application.

Claims (11)

  1. 一种包覆型锂钠复合三元正极材料，其特征在于，通式为：NaxLi0.9(NiyCozMn1-y-z)O2@A，其中x为0.027～0.1，y＝0.55～0.8，z＝0.02～0.05，A为包覆元素的氧化物，所述包覆元素为Ti、B、Co、Al、W、Zr、Sr中至少一种。A coated lithium-sodium composite ternary positive electrode material, characterized in that the general formula is: Na x Li 0.9 (Ni y Co z Mn 1-yz )O 2 @A, wherein x is 0.027-0.1, y=0.55-0.8, z=0.02-0.05, A is the oxide of the coating element, and the coating element is at least one of Ti, B, Co, Al, W, Zr, and Sr.
  2. 根据权利要求1所述包覆型锂钠复合三元正极材料，其特征在于，所述包覆型锂钠复合三元正极材料为球形或类球形颗粒，平均粒径为2～5μm。According to claim 1, the coated lithium-sodium composite ternary positive electrode material is characterized in that the coated lithium-sodium composite ternary positive electrode material is spherical or quasi-spherical particles with an average particle size of 2 to 5 μm.
  3. 权利要求1或2所述包覆型锂钠复合三元正极材料的制备方法，其特征在于，包括如下步骤：The method for preparing the coated lithium-sodium composite ternary positive electrode material according to claim 1 or 2 is characterized in that it comprises the following steps:
    S1.称取钠源和NiyCozMn1-y-z(OH)2三元前驱体，混合后进行第一次烧结，得到钠离子三元正极材料；S1. Weighing a sodium source and a Ni y Co z Mn 1-yz (OH) 2 ternary precursor, mixing them and then sintering them for the first time to obtain a sodium ion ternary positive electrode material;
    S2.将步骤S1得到的钠离子三元正极材料、锂源和NiyCozMn1-y-z(OH)2三元前驱体混合后进行第二次烧结，得到锂钠复合三元正极材料，其中，钠离子三元正极材料∶锂源中的锂∶(NiyCozMn1-y-z(OH)2三元前驱体中Ni、Co、Mn元素总摩尔量)的摩尔比为(0.08～0.18)∶0.9∶0.9，且锂源在此基础上过量5～8wt.％；S2. The sodium ion ternary positive electrode material, the lithium source and the Ni y Co z Mn 1-y z (OH) 2 ternary precursor obtained in step S1 are mixed and sintered for a second time to obtain a lithium-sodium composite ternary positive electrode material, wherein the molar ratio of the sodium ion ternary positive electrode material: lithium in the lithium source: (total molar amount of Ni, Co and Mn elements in the Ni y Co z Mn 1-y z (OH) 2 ternary precursor) is (0.08-0.18): 0.9: 0.9, and the lithium source is in excess of 5-8 wt.% on this basis;
    S3.将包覆剂与所述锂钠复合三元正极材料混合，进行第三次烧结，得到包覆型锂钠复合三元正极材料。S3. Mix the coating agent with the lithium-sodium composite ternary positive electrode material, and perform a third sintering to obtain a coated lithium-sodium composite ternary positive electrode material.
  4. 根据权利要求3所述制备方法，其特征在于，步骤S1中，所述钠源和NiyCozMn1-y-z(OH)2三元前驱体的称取量按照钠源中的钠∶(NiyCozMn1-y-z(OH)2三元前驱体中Ni、Co、Mn元素总摩尔量)的摩尔比为(0.27～1)∶1，且钠源在此基础上过量1～5wt.％进行称取。The preparation method according to claim 3 is characterized in that in step S1, the weighed amounts of the sodium source and the Ni y Co z Mn 1-yz (OH) 2 ternary precursor are according to a molar ratio of (0.27 to 1) : 1 of sodium in the sodium source : (total molar amount of Ni, Co, and Mn elements in the Ni y Co z Mn 1-yz (OH) 2 ternary precursor), and the sodium source is weighed in an excess of 1 to 5 wt.% on this basis.
  5. 根据权利要求3所述制备方法，其特征在于，所述NiyCozMn1-y-z(OH)2三元前驱体中y＝0.55～0.8，z＝0.02～0.05。The preparation method according to claim 3 is characterized in that in the Ni y Co z Mn 1-yz (OH) 2 ternary precursor, y=0.55-0.8, z=0.02-0.05.
  6. 根据权利要求3所述制备方法，其特征在于，步骤S1中，所述钠源为碳酸钠、氢氧化钠、硝酸钠、氯化钠中的至少一种。The preparation method according to claim 3, characterized in that in step S1, the sodium source is at least one of sodium carbonate, sodium hydroxide, sodium nitrate, and sodium chloride.
  7. 根据权利要求3所述制备方法，其特征在于，步骤S1中，所述第一次烧结的条件为在流量4～10m3/h的空气气氛下，以3～5℃/min升温速率，加热至 750～850℃烧结15～24h。The preparation method according to claim 3 is characterized in that in step S1, the first sintering condition is to heat to 400 °C at a heating rate of 3-5 °C/min in an air atmosphere with a flow rate of 4-10 m 3 /h. Sinter at 750-850℃ for 15-24h.
  8. 根据权利要求3所述制备方法，其特征在于，步骤S2中，所述锂源为碳酸锂、氢氧化锂、硝酸锂、氯化锂中的至少一种。The preparation method according to claim 3 is characterized in that in step S2, the lithium source is at least one of lithium carbonate, lithium hydroxide, lithium nitrate, and lithium chloride.
  9. 根据权利要求3所述制备方法，其特征在于，步骤S2中，所述第二次烧结的条件为在流量4～10m3/h的空气气氛下，以3～5℃/min升温速率加热至700～800℃保温2～4h，再以2～5℃/min升温速率加热至850～950℃烧结10～15h。The preparation method according to claim 3 is characterized in that in step S2, the second sintering conditions are: heating to 700-800°C at a heating rate of 3-5°C/min and keeping the temperature for 2-4h in an air atmosphere with a flow rate of 4-10m3/h, and then heating to 850-950°C at a heating rate of 2-5°C/min and sintering for 10-15h.
  10. 根据权利要求3所述制备方法，其特征在于，步骤S3中，所述包覆剂为含有包覆元素的化合物，所述包覆元素为Ti、B、Co、Al、W、Zr、Sr中至少一种。The preparation method according to claim 3 is characterized in that in step S3, the coating agent is a compound containing a coating element, and the coating element is at least one of Ti, B, Co, Al, W, Zr, and Sr.
  11. 根据权利要求3所述制备方法，其特征在于，步骤S3中，所述第三次烧结的条件为以2～5℃/min升温速率加热至300～700℃烧结4～8h。 The preparation method according to claim 3 is characterized in that in step S3, the conditions for the third sintering are heating to 300-700°C at a heating rate of 2-5°C/min and sintering for 4-8h.
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