WO2024061289A1 - Composite positive electrode material of sodium battery and use thereof - Google Patents

Composite positive electrode material of sodium battery and use thereof Download PDF

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Publication number
WO2024061289A1
WO2024061289A1 PCT/CN2023/120159 CN2023120159W WO2024061289A1 WO 2024061289 A1 WO2024061289 A1 WO 2024061289A1 CN 2023120159 W CN2023120159 W CN 2023120159W WO 2024061289 A1 WO2024061289 A1 WO 2024061289A1
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sodium
core
positive electrode
coating layer
composite cathode
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PCT/CN2023/120159
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French (fr)
Chinese (zh)
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刘彦辰
杨俊峰
夏圣安
徐晓东
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华为技术有限公司
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Publication of WO2024061289A1 publication Critical patent/WO2024061289A1/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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • 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
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • 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

Definitions

  • the embodiments of the present application relate to the technical field of sodium batteries, and in particular to a sodium battery composite cathode material and its application.
  • Sodium-ion batteries are batteries with a similar energy storage mechanism to lithium-ion batteries. Since sodium resources are abundant on the earth, their raw material costs are much lower than lithium. Therefore, sodium-ion batteries are more likely to meet the future demand for large-scale energy storage devices. The demand for low cost, and as a key component of sodium-ion batteries, the performance of sodium cathode materials has an important impact on the performance of sodium-ion batteries.
  • Common coating layer materials are generally materials that can consume residual alkali, such as solid electrolyte materials. Although these materials can reduce the initial residual alkali, due to the lack of effective defense against water and CO 2 in the coating layer itself, it makes the The inner core still continuously produces residual alkali; in addition, most of the coating layers are not electrochemically active, such as solid electrolyte materials. Although they can provide Na + transmission channels, they cannot contribute to the gram capacity, which easily reduces the performance of the cathode material. Specific capacity.
  • embodiments of the present application provide a core-shell sodium battery composite cathode material and its application, so as to improve the air stability of the core material without reducing the gram capacity of the core layered sodium cathode material, and endow the composite cathode with
  • the material has good storage and processing properties, as well as good electrochemical properties.
  • the first aspect of the embodiment of the present application provides a composite cathode material for a sodium battery.
  • the composite cathode material includes an inner core and a coating layer covering the inner core.
  • the inner core includes a layered sodium cathode active material, and the coating layer
  • the material of the coating is a high-voltage sodium active material with a sodium removal potential higher than that of the core.
  • the high-voltage sodium active material includes a compound represented by the general formula Na m E a J b G c
  • E is a variable valence transition metal element
  • J includes one or more of Ga, Ge, As, Se, In, Sn, Sb, Te, Tl and B
  • G includes Li, One or more of Mg, Zn, Ru, Ir; 0 ⁇ d ⁇ 4, 0 ⁇ e ⁇ 4, 0 ⁇ f ⁇ 4, 0 ⁇ g ⁇ 3,
  • R represents a metal element
  • Q represents a polyanionic group
  • F represents fluorine element.
  • the above-mentioned coating layer is provided on the surface of the layered sodium cathode active material, because the air stability of the sodium-containing cathode material is directly related to its charging potential.
  • the above-mentioned coating layer with a higher desodium potential has good stability in humid air, which can reduce the direct contact between the core material and humid air, improve the air stability of the core, and prevent its structural changes and decrease in electrochemical performance; at the same time
  • the coating layer has sodium electrochemical activity and can contribute capacity within the charge and discharge voltage window of the core material without reducing the gram capacity of the core material.
  • the high-voltage sodium active material has a sodium removal potential that is 0.2V higher than that of the core.
  • the sodium removal potential of the high-voltage sodium active material is above 3.3V.
  • the discharge gram capacity of the coating material is 50%-70% of the discharge gram capacity of the core.
  • the cladding layer not only contributes a certain capacity but does not cause excessive desodiumization, it can also reduce the unit cell volume change of the core under the high voltage window and reduce the dissolution of internal transition metals.
  • the compounds represented by the general formula Na d Re Q f F g include Na 2 CoPO 4 F, Na 2 NiPO 4 F, Na 2 MnPO 4 F, Na 2 CrPO 4 F, NaVPO 4 F, Na 3 V 2 (PO 4 ) 2 F 3 , Na 3 VCo(PO 4 ) 2 F 3 , Na 3 VNi(PO 4 ) 2 F 3 , Na 3 VMn(PO 4 ) 2 F 3 , Na 3 VCr (PO 4 ) 2 F 3 or Na 3 GaV(PO 4 ) 2 F 3 .
  • the coating layer completely covers the surface of the core. This can prevent the uncoated area of the core material from becoming an intrusion site for water, CO2, etc., better improve the storage stability of the core and the stability of the slurry during the pulping process, thereby ensuring its circulation. Stability and safety performance.
  • the mass of the material of the coating layer is 0.1wt%-20wt% of the mass of the core. This helps to form a coating layer of appropriate thickness, effectively inhibits the erosion of the core by water and CO2 in the air, and ensures good storage or processing convenience of the core material.
  • the thickness of the coating layer is 0.5nm-200nm.
  • a coating layer of appropriate thickness can effectively improve the stability of the core material in the air without significantly affecting the specific capacity of the core material.
  • the diffusion layer includes the material of the core and the material of the cladding layer.
  • the presence of the diffusion layer can improve the tightness of the bond between the core and the cladding layer.
  • the second aspect of the embodiments of the present application provides a method for preparing a composite cathode material for a sodium battery, including:
  • a coating layer is constructed on the surface of the layered sodium cathode active material to obtain a composite cathode material; wherein the material of the coating layer is a high-voltage sodium active material with a sodium removal potential higher than that of the layered sodium cathode active material,
  • the high-voltage sodium active material includes a compound represented by the general formula Na m E a J b G c On , a compound represented by the general formula Na d Re Q f F g , and Na 3 V (PO 3 ) 3 N At least one of them; among them, 0 ⁇ m ⁇ 3, 0 ⁇ a ⁇ 3, 0 ⁇ n ⁇ 3, 0 ⁇ b ⁇ 3, 0 ⁇ c ⁇ 3, E is a variable valence transition metal element, and J includes Ga, One or more of Ge, As, Se, In, Sn, Sb, Te, Tl, Bi, G includes one or more of Li, Mg, Zn, Ru, Ir; 0 ⁇ d ⁇ 4, 0 ⁇ e ⁇ 4, 0 ⁇ f ⁇ 4, 0
  • the preparation method of the composite cathode material in the embodiment of the present application has a simple process, is easy to operate, and is suitable for large-scale production.
  • the third aspect of the embodiment of the present application further provides a positive electrode plate, which includes the sodium battery composite positive electrode material described in the first aspect of the embodiment of the present application.
  • the fourth aspect of the embodiment of the present application also provides a sodium secondary battery, including the positive electrode sheet described in the third aspect of the embodiment of the present application.
  • the sodium secondary battery has good cycle performance and safety performance, and maintains high specific capacity characteristics.
  • the fifth aspect of the embodiment of the present application provides an electronic device, which includes the sodium secondary battery described in the fourth aspect of the present application.
  • the electronic device can improve the product use experience and market competitiveness.
  • the sixth aspect of the embodiment of the present application provides an energy storage system, which includes the sodium secondary battery described in the fourth aspect of the embodiment of the present application.
  • the sodium secondary battery used in this energy storage system has good cycle stability and safety performance.
  • FIG. 1A is a schematic structural diagram of a sodium battery composite cathode material provided in an embodiment of the present application.
  • Figure 1B is another structural schematic diagram of a sodium battery composite cathode material provided in an embodiment of the present application.
  • Figure 2 is a schematic structural diagram of a sodium secondary battery provided by an embodiment of the present application.
  • FIG. 3 is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application.
  • FIG. 4 is a schematic diagram of the structure of an energy storage system provided in an embodiment of the present application.
  • Figure 1A is a schematic structural diagram of a sodium battery composite cathode material 100 provided by an embodiment of the present application.
  • the composite cathode material 100 includes a core 10 and a coating layer 20 covering the core 10.
  • the core 10 includes a layered sodium cathode.
  • Active material, the material of the coating layer 20 is a high-voltage sodium active material with a sodium removal potential higher than that of the core.
  • the high-voltage sodium active material includes a compound represented by the general formula Na m E a J b G c On , At least one of the compounds represented by the general formula Na d Re Q f F g and Na 3 V (PO 3 ) 3 N; wherein, 0 ⁇ m ⁇ 3, 0 ⁇ a ⁇ 3, 0 ⁇ n ⁇ 3, 0 ⁇ b ⁇ 3, 0 ⁇ c ⁇ 3, E is a variable valence transition metal element, J includes Ga (gallium), Ge (germanium), As (arsenic), Se (selenium), In (indium), Sn (tin ), one or more of Sb (antimony), Te (tellurium), Tl (thallium), Bi (bismuth), G includes Li (lithium), Mg (magnesium), Zn (zinc), Ru (ruthenium) , one or more of Ir (iridium); 0 ⁇ d ⁇ 4, 0 ⁇ e ⁇ 4, 0 ⁇ f ⁇ 4, 0 ⁇ g ⁇ 3, R represents a metal element, Q represents a poly
  • layered sodium cathode active material in this application refers to a layered cathode active material that can store energy by desorbing and inserting sodium ions, or a layered cathode active material that can reversibly desorb and insert sodium ions.
  • High-voltage sodium active material refers to a sodium active material whose sodium removal potential is higher than that of the core material. It can be understood that the material of the cladding layer 20 and the material of the core 10 are different sodium electroactive materials; the material of the cladding layer has sodium electrochemical activity and has a higher desodium potential than the core 10 .
  • the material of the coating layer 20 may include at least one compound represented by the general formula Na m E a J b G c On , or at least one compound represented by the general formula Na d Re Q f F g Compounds, including Na 3 V(PO 3 ) 3 N, or a combination of two or more of the above three types of materials, etc.
  • Na in Na m E a J b G c On , Na d R e Q f F g , Na 3 V(PO 3 ) 3 N is sodium element
  • Na in Na m E a J b G c On O is oxygen element
  • Na 3 V(PO 3 ) 3 N is a specific compound, in which V is vanadium element, N is nitrogen element, and P is phosphorus element.
  • the sodium battery composite cathode material 100 provided in the embodiment of the present application is provided with the above-mentioned coating layer 20 on the surface of the core 10.
  • the sodium-containing coating layer can be obtained by reacting the coating layer raw material with the residual sodium on the surface of the core, which helps It is used to reduce the residual alkali on the surface of the core and lower the pH of the material.
  • the material of the coating layer 20 has a high sodium removal potential, good stability in humid air, and good defense against water and CO 2 . It can provide long-lasting protection to the core 10 and isolate the core material from the humid air.
  • the coating layer 20 also helps to stabilize the positive electrode slurry and avoid gelation and coating difficulties of the slurry caused by high residual alkali content on the surface of the core material that easily absorbs water and deteriorates. And other issues.
  • the coating layer 20 has sodium electrochemical activity, which can carry out a certain de/insertion Na + electrochemical reaction within the charge and discharge voltage window of the core material without sacrificing the gram capacity of the core material or even contributing additional grams. capacity.
  • the desodium potential of the cladding layer 20 is higher than that of the core 10, and it has better structural stability under high voltage. When the above composite material is charged in a higher voltage range, it can block the transition of the core 10. Metal ions are dissolved from the coating layer 20 into the electrolyte, stabilizing the structure of the core, avoiding side reactions with the electrolyte, and improving cycle stability.
  • the above-mentioned coating layer 20 can improve the air stability of the core 10 material without reducing the gram capacity of the core 10 material, giving the composite cathode material good storage and processing properties, as well as good cycle performance and high ratio. Capacity and other electrochemical properties are conducive to promoting the development of low-cost sodium batteries.
  • the discharge gram capacity of the material of the cladding layer 20 does not exceed 80% of the discharge gram capacity of the core 10, which is generally 50%-70%.
  • the cladding layer not only contributes to the capacity, but does not undergo excessive desodiumization, thus helping to maintain the stability of the crystal structure of the cladding layer, especially under the high voltage window, it is helpful to reduce the unit cell volume of the core material. changes, reducing the dissolution of internal transition metals and improving cycle stability.
  • the "working voltage of the core” refers to the voltage range between the charge cut-off voltage and the discharge cut-off voltage of the core material.
  • the above-mentioned composite cathode active materials are generally used in sodium-ion battery systems with a charge cut-off voltage of 2.0-4.3V. The specific charge cut-off voltage can be adjusted according to the core material.
  • the sodium removal potential of the high-voltage sodium active material is at least 0.2V higher than the sodium removal potential of the core 10 .
  • the high voltage sodium active material has a desodium potential that is 0.3 V higher than the core 10 , for example, 0.3 V to 1 V higher. Specifically, it can be high 0.32V, 0.35V, 0.4V, 0.5V, 0.6V, 0.7V, 0.8V, 0.9V or 0.95V, etc.
  • the sodium removal potential of the high-voltage sodium active material is above 3.3V.
  • the desodium potential of the compound represented by the general formula Na m E a J b G c On is above 3.3V; the compound represented by the polyanionic sodium active material (Na d Re Q f F g , Na 3 V
  • the desodium potential of (PO 3 ) 3 N) is above 3.3V, even above 3.5V.
  • the compound represented by the general formula Na m E a J b G c On is a high voltage oxide containing sodium and transition metal elements.
  • the compound must contain sodium element, oxygen element, E element and J element.
  • Element, the G element is optional and can contain G elements in some cases.
  • J elements such as Ga, Ge, As, Se, In, Sn, Sb, Te, Tl, and Bi help to build a honeycomb structure compound Na m E a J b G c O n and help improve its sodium removal potential. , thereby making it have higher air stability, so as to better protect the core material from water, CO 2 , etc.
  • the E may include V (vanadium), Cr (chromium), Fe (iron), Co (cobalt), Ni (nickel), Mn (manganese), Cu (copper), Ti (titanium) one or more of them.
  • the G includes one or more of Mg, Ru, and Ir. When G is these elements, the desodium potential of the compound Na m E a J b G c On is higher.
  • the compound represented by the general formula Na d Re Q f F g and Na 3 V (PO 3 ) 3 N are both polyanionic compounds of sodium, and their desodium potentials are relatively high. It has higher stability than the layered sodium cathode active material. Using it as a coating material for the layered sodium cathode active material can improve the air stability of the core. Since this polyanionic compound has sodium electrochemical activity, it is used as a coating material. The cladding material will not reduce the specific capacity of the overall composite material.
  • the compound represented by the general formula Na d Re Q f F g contains both the polyanionic group Q and the fluorine (F) element. The presence of F element can increase the desodium potential of the polyanionic compound through the strong induction effect of fluoride ions, making it have high air stability and facilitate the protection of the core material.
  • R represents a metal element.
  • the metal elements here include but are not limited to transition metal elements and/or main group metal elements, and transition metal elements are more common.
  • R can be selected from V (vanadium), Cr (chromium), Fe (iron), Co (cobalt), Ni (nickel), Mn (manganese), Cu (copper), Ti (titanium), One or more of Zr (zirconium), Al (aluminum), etc., but not limited to this.
  • the polyanion group Q can be selected from one or more of phosphorus oxyacid radicals, sulfur oxyacid radicals, silicon oxyacid radicals, boron oxyacid radicals, and the like.
  • the oxygen-containing acid radical of phosphorus may include one or more of PO 4 3- , PO 3 3- , P 2 O 7 4- , HPO 4 2- , H 2 PO 4 - , etc.; the oxygen-containing acid radical of sulfur The acid radical may include one or more of SO 4 2- , SO 3 2- , HSO 4 - , etc.; the oxygen-containing acid radical of silicon may include one or more of SiO 4 4- , SiO 3 2- , etc.;
  • the oxygen-containing acid radical of boron may include one or more of BO 3 3- , BO 2- , B 4 O 7 2- , B 5 O 10 5- , etc.
  • the compounds represented by the general formula Na d Re Q f F g specifically include Na 2 CoPO 4 F, Na 2 NiPO 4 F, Na 2 MnPO 4 F, Na 2 CrPO 4 F, and NaVPO 4 F , Na 3 V 2 (PO 4 ) 2 F 3 , Na 3 VCo(PO 4 ) 2 F 3 , Na 3 VNi(PO 4 ) 2 F 3 , Na 3 VMn(PO 4 ) 2 F 3 , Na 3 VCr( PO 4 ) 2 F 3 or Na 3 GaV(PO 4 ) 2 F 3 .
  • These polyanionic compounds have higher sodium removal potentials and better air stability. Their sodium removal potentials are generally between 3.3V or above.
  • the sodium ion conductivity of the coating material at 20°C is ⁇ 10 -5 S ⁇ cm -1 .
  • the layered sodium cathode active material is a transition metal oxide of sodium.
  • the layered sodium cathode active material can be expressed as Na x A y M z D u O v , where 0 ⁇ x ⁇ 12, 0 ⁇ y ⁇ 12, 0 ⁇ z ⁇ 12, 0 ⁇ u ⁇ 12, 0 ⁇ v ⁇ 12.
  • A is a variable valence transition metal element.
  • A may include V (vanadium), Cr (chromium), Fe (iron), Co (cobalt), Ni (nickel), Mn (manganese), Cu (copper ), one or more of Ti (titanium).
  • M is an element that can substitute/dope transition metal elements.
  • M can include Li (lithium), Al (aluminum), Mg (magnesium), Ca (calcium), K (potassium), Zn (zinc), Sn ( Tin), etc.; D includes one or more of C (carbon), P (phosphorus), Si (silicon), B (boron), W (tungsten).
  • the particle size of the layered sodium cathode active material is 50 nm-30 ⁇ m.
  • the particle size of the layered sodium cathode active material is larger, its specific surface area should not be too large, and its structural stability is high. However, the particle size should not be too large to avoid increasing the diffusion path of sodium ions in it and degrading its rate performance.
  • the particle size of the layered sodium cathode active material ranges from 500 nm to 20 ⁇ m. Layered sodium cathode active materials with appropriate particle sizes can achieve both high structural stability and short sodium ion diffusion paths.
  • the coating layer 20 completely covers the surface of the core 10 . This can prevent the uncoated area of the layered sodium cathode active material from becoming an invasion site for water, CO2, etc., better improve the storage stability of the core, and the stability of the slurry during the pulping process, thereby ensuring its Cycling stability and safety performance.
  • the thickness of the coating layer 20 may be 0.5nm-200nm.
  • a coating layer of appropriate thickness can effectively inhibit the reaction between the layered sodium cathode active material and water and CO 2 in humid air, improve the stability of the core material in the air, and will not be affected by the thickness of the coating layer 20 being too thick The specific capacity of the core material is exerted and the energy density of the sodium battery is reduced.
  • the thickness of the coating layer 20 may be 1 nm, 2 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 80 nm, 90 nm, 100 nm, 120 nm, 150 nm, 180 nm, 200 nm, etc.
  • the thickness of the cladding layer 20 may be 2 nm-100 nm. In other embodiments, the thickness of the cladding layer 20 is 10 nm-80 nm.
  • the mass of the coating layer material may be 0.1wt%-20wt% of the mass of the core material (ie, layered sodium cathode active material).
  • the coating layer can also inhibit side reactions between the core and the electrolyte to ensure that the capacity of the core is fully exerted.
  • the mass of the cladding material may be 0.2wt%, 0.5wt%, 1wt%, 2wt%, 5wt%, 8wt%, 10wt%, 12wt%, 15wt% or 18wt% of the core material mass, etc.
  • the mass of the cladding material is 0.5wt%-20wt% of the core material; in other embodiments, the mass ratio is 1wt%-15wt%.
  • the bulk phase of the core 10 may be doped with elements derived from the coating layer 20.
  • the element doped into the bulk phase of the core includes J element, or J element+ G element, or E element different from the A element in the core.
  • the element doped into the bulk phase of the core is a metal element R, generally a transition metal element. Bulk phase doping helps to improve the ionic conductivity and structural stability of the core material, thereby significantly improving the rate performance and cycle stability of the composite positive electrode material 100.
  • a diffusion layer 12 is further provided between the core 10 and the coating layer 20 of the composite positive electrode material 100, and the diffusion layer 12 includes the material of the core 10 (i.e., the layered sodium positive electrode active material) and the material of the coating layer 20.
  • the diffusion layer 12 may be formed by mutual diffusion of the core material and the coating layer material, and the diffusion layer 12 and the core 10 may have a continuous layered sodium positive electrode active material bulk phase, and the diffusion layer 12 and the coating layer 20 may have a continuous coating layer material bulk phase.
  • the presence of the diffusion layer can improve the tightness of the bonding between the core 10 and the coating layer 20, enhance the transmission of sodium ions and electrons at the core interface, and effectively restrain the dissolution of transition metal elements in the bulk phase of the sodium positive electrode active material, stabilize its lattice structure, and significantly improve the cycle stability.
  • the cladding material diffuses into the bulk phase of the core material, and/or at the surface, forming JOA bonds or ROA bonds.
  • A is a transition metal element in the core material
  • J is an element derived from the cladding material Na m E a J b G c On
  • R is a non-sodium metal element derived from the polyanionic cladding material.
  • the ions corresponding to the J element such as Sn 4+ and Sb 5+ , all belong to the d10 electronic structure and will not hybridize with the O 2p orbital. Therefore, they help change the coordination of oxygen atoms in the layered sodium cathode active material.
  • the environment enhances the interaction of AO bonds, thereby improving the stability of the lattice structure of the layered cathode active material and improving the electrochemical performance of the composite material.
  • the thickness of the diffusion layer 12 mainly depends on the mutual diffusion ability of the cladding material and the core material, especially the diffusion ability of the cladding material to the core 10 .
  • the thickness of the diffusion layer 12 may be 0.1 nm-20 nm. Specifically, it can be 0.2nm, 0.5nm, 1nm, 1.5nm, 2nm, 5nm, 10nm, 15nm, etc. In some embodiments, the thickness of the diffusion layer 12 is 0.2nm-10nm; in some embodiments, the thickness of the diffusion layer 12 is 0.2nm-5nm.
  • Embodiments of the present application also provide a method for preparing the above composite cathode material.
  • the preparation method may include:
  • a coating layer is constructed on the surface of the layered sodium cathode active material to obtain a composite cathode material; wherein the material of the coating layer is a high-voltage sodium active material with a sodium removal potential higher than that of the layered sodium cathode active material,
  • the high-voltage sodium active material includes compounds represented by the general formula Na m E a J b G c On , compounds represented by the general formula Na d Re Q f F g , and Na 3 V (PO 3 ) 3 N.
  • E is a variable valence transition metal element
  • J includes Ga, Ge, One or more of As, Se, In, Sn, Sb, Te, Tl, Bi
  • G includes one or more of Li, Mg, Zn, Ru, Ir; 0 ⁇ d ⁇ 4, 0 ⁇ e ⁇ 4, 0 ⁇ f ⁇ 4, 0 ⁇ g ⁇ 3,
  • R represents a metal element
  • Q represents a polyanion group
  • F is a fluorine element.
  • the above-mentioned coating layer can be constructed by mixing the layered sodium positive electrode active material and the coating layer material or the raw material of the synthetic coating layer material.
  • the construction method of the coating layer includes but is not limited to one or more of solid phase method, liquid phase method and other methods.
  • the solid phase method can be mechanical stirring method, solid phase high energy ball milling method, mechanical fusion method, etc.
  • the liquid phase method can be sol-gel method, hydrothermal/solvent thermal coating method, co-precipitation coating method, liquid phase high energy ball milling One or more of method, coating method, spray drying coating method.
  • Other methods may be one or more selected from atomic layer deposition, chemical vapor deposition, physical vapor deposition (such as magnetron sputtering, plasma sputtering, evaporation), microwave reaction, etc.
  • atomic layer deposition chemical vapor deposition
  • physical vapor deposition such as magnetron sputtering, plasma sputtering, evaporation
  • microwave reaction etc.
  • a high-temperature sintering treatment is required to promote the crystallization of the coating material and enhance its bonding force with the sodium cathode active material.
  • the preparation method of the above composite cathode material may specifically include:
  • the coating layer raw material is a high-voltage sodium active material or an element for synthesizing the high-voltage sodium active material
  • the high-voltage sodium active material includes compounds represented by the general formula Na m E a J b G c
  • N At least one of N; among them, 0 ⁇ m ⁇ 3, 0 ⁇ a ⁇ 3, 0 ⁇ n ⁇ 3, 0 ⁇ b ⁇ 3, 0 ⁇ c ⁇ 3,
  • E is a variable valence transition metal element
  • J includes Ga , one or more of Ge, As, Se, In, Sn, Sb, Te, Tl, Bi
  • G includes one or more of Li, Mg, Zn, Ru, Ir; 0 ⁇ d ⁇ 4 , 0 ⁇ e ⁇ 4, 0 ⁇ f ⁇ 4, 0 ⁇ g ⁇ 3, R represents the metal element
  • Q represents
  • the composite positive electrode material includes a core and a coating layer coated on the core, the core includes a layered positive electrode active material, and the coating layer includes the metal oxide.
  • the method of coating the precursor of the coating layer material includes the above-mentioned in-situ reaction coating method.
  • the in-situ reaction coating method mainly refers to mixing the raw materials for synthesizing the coating layer material and the cathode active material, While the coating layer material precursor is prepared through in-situ reaction, the positive electrode active material is coated.
  • the cladding layer material precursor can be transformed into the cladding layer material after the sintering process in step S02.
  • the mixing method may be one or more of the aforementioned solid phase method, liquid phase method, and other methods.
  • the coating layer raw materials used in step S01 are various element sources of high-voltage sodium active materials
  • the coating layer raw materials used in step S01 are various element sources of high-voltage sodium active materials
  • after the mixing process in step S01, while preparing the coating layer material precursor Realize coating of layered sodium cathode active material.
  • the cladding layer material precursor can be transformed into the cladding layer material after the sintering process in step S02.
  • the cladding raw materials specifically include sodium sources, metal R sources (i.e., containing metal Raw material of element R), polyanionic group source and fluorine source.
  • the sodium source may be one or more of Na hydroxide, carbonate, nitrate, oxalate, acetate, sulfate, phosphate, and fluorine-containing salt.
  • the metal R source may specifically include oxides, hydroxides, carbonates, nitrates, oxalates, acetic acid, etc.
  • the fluorine source may be one or more of NH 4 F, NH 4 HF 2 , NaF, etc.
  • the source of the polyanion group (Q) includes one or more of the oxygen-containing acid radicals of P, the oxygen-containing acid radicals of S, the oxygen-containing acid radicals of Si, the oxygen-containing acid radicals of B, etc., wherein the oxygen-containing acid radicals of P Can be selected from NH 4 H 2 PO 4 , (NH 4 ) 2 HPO 4 , (NH 4 ) 3 PO 4 , H 3 PO 4 , NH 4 H 2 PO 3 , (NH 4 ) 2 HPO 3 , H 3 PO 3 , one or more of (NH 4 ) 4 P 2 O 7 ; the oxygen-containing acid radical of S may include one or more of Na 2 SO 4 , NaHSO 4 , Na 2 SO 3 ; the oxygen-containing acid of Si
  • the source is selected from one or more of Na 2 O.nSiO 2 , H 2 SiO 3 , C 8 H 20 O 4 Si (TEOS);
  • the oxygen-containing acid source of B is selected from H 3 BO 3 , HBO 2 ,
  • the source of raw materials for synthesizing Na 3 V(PO 3 ) 3 N is similar to the polyanionic compound with the general formula Na d Re Q f F g , and may include a sodium source, a vanadium source, a phosphorus source and a nitrogen source.
  • these raw material sources can be two into one, or more than one into one.
  • the sodium source and the phosphorus source can be the same material.
  • the coating raw materials specifically include sodium source, element E source, J source and optional G element source.
  • the raw materials of E, J, and G elements can be selected from oxides, hydroxides, carbonates, nitrates, oxalates, acetates, sulfates, phosphates, fluorine-containing salts, etc. of the corresponding elements, and the final Very oxygenated.
  • the sol-gel method can be used to construct its precursor (for example, its hydroxide), which specifically includes: combining lithium source, elements
  • its precursor for example, its hydroxide
  • the raw materials of E, the raw materials of element J and the optional raw materials of element G are added to the solvent with the layered sodium cathode active material, and the reaction is carried out under stirring conditions.
  • the solvent is then evaporated to dryness, and a package is formed on the surface of the layered sodium cathode active material. Cladding precursor material.
  • the stirring reaction time can be 20-60 minutes.
  • the solvent used may include one or more of water, ethanol, acetone, etc.
  • the heating temperature used to evaporate the solvent is 60°C-100°C.
  • the element sources used may not contain sodium sources, and the sodium element in the final coating layer It can be derived from the layered sodium cathode active material, for example specifically from the residual sodium on its surface, that is, the coating layer can be obtained by consuming the residual sodium on the surface of the core.
  • a solid-phase method may be used to perform the mixing of step S01.
  • the solid phase method can specifically be a mechanical stirring method, a high-energy ball milling method, a mechanical fusion method, etc.
  • the solid phase mixing time in the solid phase method is 2h-24h, and may further be 10-24h.
  • the solidification mixing can be achieved specifically through a ball milling method, thereby realizing the convenient preparation of core-shell composite materials.
  • the rotation speed of the ball mill can be 100-700r/min, for example, it can be 200r/min, 300r/min, 400r/min, 450r/min, 500r/min, 550r/min, 600r/min, 650r/min, etc. In some embodiments, the rotation speed of the ball mill can be 400-700 r/min.
  • the coating layer raw material used in step S01 is the required high-voltage sodium active material
  • the surface of the layered sodium cathode active material can be coated The above-mentioned high-voltage sodium active material.
  • the coating layer raw material used in step S01 is a high-voltage sodium active material
  • the binding force between the core layered sodium cathode active material and the coating layer can be improved through the sintering process in step S02;
  • the coating layer used in step S01 When the raw material of the coating layer is the raw material source for synthesizing the high-voltage sodium active material, through the sintering process in step S02, the coating layer material-the high-voltage sodium active material can be obtained while tightly coating the core.
  • the first composite material is sintered, and a diffusion layer may be formed between the core and the cladding layer.
  • the diffusion layer includes a core material and a cladding layer material.
  • the sintering treatment can not only improve the binding force between the core layered sodium cathode active material and the coating layer, but also promote the interdiffusion of the core and the coating layer to form a diffusion layer, enhancing the interaction between sodium ions and electrons at the interface between the two. transmission on.
  • the sintering process in step S02 can be performed in an atmosphere such as oxygen, air, nitrogen, argon, helium, etc.
  • the sintering temperature and holding time during the sintering process are measured in the embodiments of this application.
  • the sintering temperature in the sintering process can be 200-900°C, and the sintering holding time can be 0.5h-12h.
  • the sintering temperature may be 250, 300, 400, 500, 600, 650, 700, 800 or 850°C, etc.
  • the sintering temperature may be 300-700°C.
  • the sintering heat preservation time can be specifically 1h, 2h, 4h, 5h, 6h, 7h, 8h, 9h, 10h or 11h, etc.
  • the temperature rise rate during the sintering process can be 0.5-20°C/min, such as 1, 2, 3, 5, 8, 10, 15°C/min, etc.
  • the heating rate may be 0.5-5°C/min. This can prevent the heating rate from being too fast and causing large stress on the interface between the phases.
  • the powder is collected after natural cooling to obtain the composite cathode material.
  • the powder collected after sintering can also be crushed and refined to obtain a composite cathode material with a desired particle size.
  • the preparation method of the composite cathode material provided by the embodiments of the present application has low raw material cost, simple process, easy operation, and is suitable for large-scale production.
  • An embodiment of the present application also provides a positive electrode sheet for a sodium battery, which includes the sodium battery composite positive electrode material described above in the embodiment of the present application.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode material layer disposed on the positive electrode current collector.
  • the positive electrode material layer includes the composite positive electrode material described in the embodiments of the present application.
  • the cathode material layer may also include a binder and a conductive agent. In some embodiments, the cathode material layer may also include other cathode active materials.
  • the positive electrode current collector is a common choice in the field of sodium batteries, and can be, for example, aluminum foil, carbon-coated aluminum foil, or aluminum-plated polymer film.
  • the binder may specifically include, but is not limited to, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), polyimide (PI), polyacrylic acid (PAA), polyacrylate, One or more of polyacrylamide (PAM), carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), sodium alginate, etc.
  • the conductive agent may specifically include, but is not limited to, one or more of acetylene black, Ketjen black, Super P conductive carbon black, graphite, graphene, carbon nanotubes, carbon fiber, amorphous carbon, etc.
  • the preparation method of the positive electrode sheet may include: mixing the above-mentioned composite positive electrode materials, conductive agents, binders and solvents implemented in this application to prepare positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and drying Then roll it to obtain the positive electrode piece.
  • an embodiment of the present application also provides a sodium secondary battery 200, which includes the above-mentioned positive electrode plate.
  • the sodium secondary battery 200 includes a positive electrode 201, a negative electrode 202, a separator 203 disposed between the positive electrode 201 and the negative electrode 202, an electrolyte 204, and corresponding connecting accessories and circuits, wherein the positive electrode 201 includes the positive electrode described in the embodiment of the present application. Extreme piece.
  • sodium ions escape from the positive electrode 201 and migrate to the negative electrode 202 through the electrolyte 204 and the diaphragm 203, while electrons flow from the positive electrode to the negative electrode through the external circuit, and electrical energy is stored; the discharge process is opposite to the charging process, sodium ions escape from the negative electrode 202 and return to the positive electrode 201 through the electrolyte 204 and the diaphragm 203, while electrons migrate from the negative electrode to the positive electrode through the external circuit, releasing electrical energy to the outside. Since the sodium secondary battery uses the above-mentioned composite positive electrode material 100, it has good cycle stability, safety performance and rate performance within its operating voltage range.
  • the negative electrode 202 may include a negative electrode current collector and a negative electrode material layer disposed on the negative electrode current collector.
  • the negative electrode material layer includes a negative electrode active material, Adhesive and optional conductive agent.
  • the negative electrode current collector includes but is not limited to metal foil, alloy foil or metallized film, and its surface can be etched or roughened to form a secondary structure to facilitate effective contact with the negative electrode material layer.
  • Exemplary metal foils may be copper foil, carbon-coated copper foil or copper-plated film, and exemplary alloy foils may be stainless steel foils, copper alloy foils, etc.
  • the negative active material includes, but is not limited to, one or more of carbon-based materials, silicon-based materials, tin-based materials, and phosphorus-based materials.
  • carbon-based materials can include non-graphitized carbon (soft carbon, hard carbon, mesocarbon microspheres, etc.), graphite (such as natural graphite, artificial graphite); silicon-based materials can include elemental silicon, silicon-based alloys, silicon oxide One or more of materials and silicon-carbon composite materials; tin-based materials can include one or more of elemental tin, tin alloys, tin oxides, tin-carbon composite materials, etc.; phosphorus-based materials can include elemental phosphorus (such as black phosphorus), phosphorus carbon composite materials, etc.
  • the separator 203 can be a polymer separator, non-woven fabric, etc., including but not limited to single-layer PP (polypropylene), single-layer PE (polyethylene), double-layer PP/PE, double-layer PP/PP and three-layer PP/PE. /PP and other separators.
  • the electrolyte 204 includes a lithium salt and a non-aqueous organic solvent.
  • the non-aqueous organic solvent may include one or more of carbonate solvents, carboxylate solvents, and ether solvents.
  • the sodium secondary battery of the embodiment of the present application can be used in terminal consumer products, such as mobile phones, tablet computers, mobile power supplies, portable machines, notebook computers, digital cameras, and other wearable electronic devices or movable electronic devices, such as drones, Products such as electric bicycles and electric vehicles to improve product performance.
  • An embodiment of the present application also provides an electronic device including the sodium secondary battery 200 provided in the embodiment of the present application.
  • the electronic device may include various consumer electronic products, such as mobile phones, tablet computers, notebook computers, mobile power supplies, portable machines, and other wearable or removable electronic devices, televisions, DVD players, video recorders, and camcorders. , radios, cassette players, combo stereos, record players, compact disc players, home office equipment, home electronic health care equipment, and also electronic products such as automobiles and energy storage equipment.
  • consumer electronic products such as mobile phones, tablet computers, notebook computers, mobile power supplies, portable machines, and other wearable or removable electronic devices, televisions, DVD players, video recorders, and camcorders.
  • the electronic device 300 includes a housing 301 and electronic components (not shown in FIG. 3 ) accommodated in the housing 301 and a battery 302 .
  • the battery 302 supplies power to the electronic device 300 .
  • the battery 302 Including the sodium secondary battery 200 described in the embodiment of the present application.
  • the housing 301 may include a front cover assembled on the front side of the terminal and a rear shell assembled on the rear side, and the battery 302 may be fixed inside the rear shell.
  • the electronic device provided in the embodiment of the present application adopts the composite positive electrode material provided in the embodiment of the present application as the positive electrode active material of the battery, which can meet the requirements of various electronic products for good thermal stability, long cycle life, and high energy density of the battery, thereby improving the user experience and market competitiveness of the electronic products.
  • an embodiment of the present application also provides an energy storage system 400.
  • the energy storage system 400 includes a battery pack 401 and a battery management system 402 electrically connected to the battery pack 401.
  • the battery pack 401 includes the sodium chloride provided in the embodiment of the present application. Secondary battery 200.
  • a and/or B can represent: A exists alone, A and B exist at the same time, and B exists alone.
  • at least one means one or more; “multiple” means more than two (i.e., greater than or equal to two). The meanings of "at least one" and “multiple” are similar.
  • core material - layered sodium cathode active material NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (average particle size is 3-10 ⁇ m)
  • mix 100g of this core material with 0.36g of antimony oxide (Sb 2 O 3 ) Powder and 1.25g of nickel acetate tetrahydrate (Ni(CH 3 COO) 2 ⁇ 4H 2 O) are mixed and ball-milled at 300 rpm for 10 hours.
  • the ball-milled material is placed in a tube furnace for sintering.
  • the method is: from room temperature to a sintering temperature of 800°C at a heating rate of 5°C/min, and then kept and sintered at this temperature for 3 hours; then naturally cooled to room temperature to obtain a composite cathode material.
  • the composite cathode material includes a NaNi 1/3 Fe 1/3 Mn 1/3 O 2 core and a Na m Ni 2/3 Sb 1/3 O 2 coating layer formed on the surface of the core, with m between 0.5-1.0 .
  • the composite cathode material can be recorded as NaNi 1/3 Fe 1/3 Mn 1/3 O 2 @Nam Ni 2/3 Sb 1/3 O 2 .
  • the thickness of the cladding layer is 10nm, and the mass of the cladding layer accounts for 1.0% of the core mass.
  • Example 1 Mix the composite cathode material of Example 1 with the conductive agent Super P and the binder PVDF in a mass ratio of 92:4:4, add an appropriate amount of N-methylpyrrolidone (NMP), and grind evenly to obtain a cathode slurry; The slurry is evenly coated on the aluminum foil, dried and rolled to obtain the pole piece.
  • NMP N-methylpyrrolidone
  • the preparation of a composite cathode material includes the following steps:
  • a core material - layered sodium cathode active material NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (same as Example 1), mix 100g of this core material with 0.65g of tin oxide (SnO 2 ) powder, 0.54 g of nickel acetate tetrahydrate (Ni(CH 3 COO) 2 ⁇ 4H 2 O) was mixed, ball milled and then sintered in a tube furnace, and naturally cooled to room temperature to obtain a composite cathode material; the ball milling and sintering conditions were the same as in the implementation example 1.
  • the composite cathode material obtained in Example 2 includes a NaNi 1/3 Fe 1/3 Mn 1/3 O 2 core and a Na m Ni 1/3 Sn 2/3 O 2 coating layer formed on the surface of the core.
  • the composite cathode material is The material is recorded as NaNi 1/3 Fe 1/3 Mn 1/3 O 2 @Na m Ni 1/3 Sn 2/3 O 2 , where m is between 0.5-1.0.
  • the thickness of the cladding layer is 10nm, and the mass of the cladding layer accounts for 1.0% of the core mass.
  • a preparation method of a composite positive electrode material comprises the following steps:
  • Example 1 Provide a core material—layered sodium cathode active material NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (same as Example 1), mix 100g of this core material with 1g of Na 0.67 Ni 1/3 As 2/3 O 2 is mixed, ball-milled, then sintered in a tube furnace, and naturally cooled to room temperature to obtain a composite cathode material; the ball-milling and sintering conditions are the same as in Example 1.
  • the composite cathode material prepared in Example 3 includes a NaNi 1/3 Fe 1/3 Mn 1/3 O 2 core and a Na m Ni 1/3 As 2/3 O 2 coating layer formed on the surface of the core.
  • the composite The positive electrode material is recorded as NaNi 1/3 Fe 1/3 Mn 1/3 O 2 @Na m Ni 1/3 As 2/3 O 2 , m is between 0.5-1.0. Among them, the thickness of the cladding layer is 8nm.
  • the preparation of a composite cathode material includes the following steps:
  • core material layered sodium cathode active material NaAl 0.05 Ni 0.35 Fe 0.2 Mn 0.4 O 2 (average particle size 3-10 ⁇ m), mix 100g of this core material with 0.32g copper oxide (CuO) powder, 1.34g Tellurium oxide (TeO 2 ) is mixed and ball-milled at a rotation speed of 250 rpm for 8 hours.
  • the ball-milled material is placed in a tube furnace for sintering.
  • the sintering conditions are: from room temperature to a sintering temperature of 800 at a heating rate of 5°C/min. °C, kept and sintered at this temperature for 3 hours; then naturally cooled to room temperature to obtain the composite cathode material.
  • the composite cathode material prepared in Example 4 includes a NaAl 0.05 Ni 0.35 Fe 0.2 Mn 0.4 O 2 core and a Na m Cu 1/3 Te 2/3 O 2 coating layer formed on the surface of the core.
  • the composite cathode material is recorded as NaAl 0.05 Ni 0.35 Fe 0.2 Mn 0.4 O 2 @N m Cu 1/3 Te 2/3 O 2 , m is between 0.5-1.0.
  • the thickness of the cladding layer is 15nm, and the mass of the cladding layer accounts for approximately 2.0% of the mass of the core material.
  • the preparation of a composite cathode material includes the following steps:
  • CuO copper oxide
  • TeO 2 0.67g Tellurium oxide
  • the composite cathode material prepared in Example 5 includes a NaZn 0.05 Ni 0.35 Fe 0.2 Mn 0.4 O 2 core and a Na m Cu 1/3 Te 2/3 O 2 coating layer formed on the surface of the core.
  • the composite cathode material can be recorded as NaZn 0.05 Ni 0.35 Fe 0.2 Mn 0.4 O 2 @N m Cu 1/3 Te 2/3 O 2 , m is between 0.5-1.0.
  • the thickness of the cladding layer is 14nm, and the mass of the cladding layer accounts for approximately 1.0% of the core mass.
  • a preparation method of a composite positive electrode material comprises the following steps:
  • core material - layered sodium cathode active material NaCa 0.02 Ni 0.33 Fe 0.33 Mn 0.33 O 2 (single crystal, average particle size is 5-7 ⁇ m)
  • mix 100g of this core material with 1g of Na 0.8 Mg 0.1 Ni 1/3 Bi 2/3 O 2 is mixed and ball-milled at 300 rpm for 10 hours.
  • the ball-milled material is placed in a tube furnace for sintering.
  • the sintering conditions are: from room temperature to a sintering temperature of 700 at a heating rate of 3°C/min. °C, kept and sintered at this temperature for 4 hours; then naturally cooled to room temperature to obtain the composite cathode material.
  • the composite cathode material prepared in Example 6 includes a NaCa 0.02 Ni 0.33 Fe 0.33 Mn 0.33 O 2 core, and a Na m Mg 0.1 Ni 1/3 Bi 2/3 O 2 coating layer formed on the surface of the core, with m in 0.5- between 1.0.
  • the thickness of the cladding layer is 10nm, and the mass of the cladding layer accounts for 1.0% of the core mass.
  • the preparation of a composite cathode material includes the following steps:
  • core material - layered sodium cathode active material Na 2 Mn 3 O 7 (single crystal, average particle size is 5-7 ⁇ m)
  • mix 100g of this core material with 1g of Na 0.67 Li 0.1 Ni 1/3 Bi 2/3 O 2 (average particle size does not exceed 500 nm) is mixed, ball milled and then sintered in a tube furnace, and naturally cooled to room temperature to obtain a composite cathode material; the ball milling and sintering conditions are the same as in Example 6.
  • the composite cathode material prepared in Example 7 includes a Na 2 Mn 3 O 7 core and a Na m Li 0.1 Ni 1/3 Bi 2/3 O 2 coating layer formed on the surface of the core, with m between 0.5 and 1.0.
  • the composite cathode material is denoted as Na 2 Mn 3 O 7 @N m Li 0.1 Ni 1/3 Bi 2/3 O 2 .
  • the thickness of the cladding layer is 9nm.
  • the preparation of a composite cathode material includes the following steps:
  • a core material—layered sodium cathode active material NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (same as Example 1), mix 100g of this core material with 1.5g of Na 0.67 Ca 0.05 Ni 1/3 Ge 2/3 O 2 was mixed and ball milled at a speed of 200 rpm for 5 hours.
  • the ball-milled material was placed in a tube furnace for sintering.
  • the sintering conditions were: from room temperature to a sintering temperature of 600°C at a heating rate of 5°C/min. Maintain and sinter at this temperature for 3 hours; then naturally cool to room temperature to obtain a composite cathode material.
  • the composite cathode material prepared in Example 8 includes a NaNi 1/3 Fe 1/3 Mn 1/3 O 2 core and a Na 0.67 Ca 0.05 Ni 1/3 Ge 2/3 O 2 coating layer formed on the surface of the core .
  • the thickness of the cladding layer is 9nm, and the mass of the cladding layer accounts for 1.5% of the core mass.
  • the preparation of a composite cathode material includes the following steps:
  • core material - layered sodium cathode active material NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (average particle size is 3-10 ⁇ m)
  • mix 100g of this core material with 1g of Na 3 (VPO 4 ) 2 F 3 (average particle size does not exceed 500 nm) is mixed, ball milled and then sintered in a tube furnace, and naturally cooled to room temperature to obtain a composite cathode material; the ball milling and sintering conditions are the same as in Example 1.
  • the composite cathode material prepared in Example 9 includes a NaNi 1/3 Fe 1/3 Mn 1/3 O 2 core and a Na 3 V 2 (PO 4 ) 2 F coating layer formed on the surface of the core.
  • This composite cathode material is denoted as NaNi 1/3 Fe 1/3 Mn 1/3 O 2 @Na 3 (VPO 4 ) 2 F 3 .
  • the thickness of the cladding layer is 5nm.
  • the preparation of a composite cathode material includes the following steps:
  • core material - layered sodium cathode active material NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (average particle size is 3-10 ⁇ m)
  • average particle size (particle size not exceeding 500 nm) mixed, ball milled and then sintered in a tube furnace, and naturally cooled to room temperature to obtain a composite cathode material; the ball milling and sintering conditions were the same as in Example 1.
  • the composite cathode material prepared in Example 10 includes a NaNi 1/3 Fe 1/3 Mn 1/3 O 2 core and a Na 2 MnPO 4 F coating layer formed on the surface of the core.
  • This composite cathode material is denoted as NaNi 1/3 Fe 1/3 Mn 1/3 O 2 @Na 2 CoPO 4 F.
  • the thickness of the cladding layer is 6nm.
  • Example 1 Directly use uncoated NaNi 1/3 Fe 1/3 Mn 1/3 O 2 as the positive active material, and assemble it into a button sodium battery in the same manner as in Example 1.
  • each composite cathode material was also The positive electrode slurry was prepared in the manner described in Example 1 above, and the time required for the positive electrode slurry to undergo gelation in an environment with a humidity of 10% was tested. The relevant results are summarized in Table 1 below.
  • Table 1 also summarizes the sodium removal potential of the core material and the sodium removal potential of the coating layer material in the composite material of the embodiment of the present application. The sodium removal potentials of the two are tested on separate materials, not on the composite material.
  • each button battery was subjected to a current of 0.5C rate at 25°C.
  • the voltage range is 2.0-4.1V, record the discharge capacity at each cycle number, where the first cycle discharge specific capacity is equal to the ratio of the first discharge capacity of the button battery to the mass of the positive active material of the button battery; cycle The capacity retention rate after 50 cycles is equal to the ratio of the discharge capacity after 50 cycles to the first discharge capacity.
  • Table 1 The relevant results are summarized in Table 1.

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Abstract

Provided are a composite positive electrode material of a sodium battery and a use thereof. The composite positive electrode material comprises an inner core and a cladding layer cladding the inner core; the inner core comprises a layered sodium positive electrode active material, and the material of the cladding layer has higher sodium removal potential than that of the inner core and comprises at least one of a substance represented by general formula NamEaJbGcOn, a substance represented by general formula NadReQfFg, and Na3V(PO3)3N; 0<m≤3, 0<a≤3, 0<n≤3, 0<b≤3, and 0≤c≤3, E is a variable-valence transition metal element, J comprises at least one of Ga, As, Se, In, Sn, Sb, Te, Tl, and Bi, and G comprises at least one of Li, Mg, Zn, Ru, and Ir; 0<d≤4, 0<e≤4, 0<f≤4, and 0<g≤3, R is a metal element, and Q represents a polyanionic group. The composite positive electrode material has good air stability and higher specific capacity.

Description

钠电池复合正极材料及其应用Sodium battery composite cathode materials and their applications
本申请要求于2022年9月23日提交至中国专利局、申请号为202211166710.2、申请名称为“钠电池复合正极材料及其应用”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。This application claims priority to the Chinese patent application filed with the China Patent Office on September 23, 2022, with application number 202211166710.2 and application name “Sodium battery composite positive electrode materials and their applications”, the entire contents of which are incorporated by reference in this application.
技术领域Technical field
本申请实施例涉及钠电池技术领域，特别是涉及一种钠电池复合正极材料及其应用。The embodiments of the present application relate to the technical field of sodium batteries, and in particular to a sodium battery composite cathode material and its application.
背景技术Background technique
钠离子电池是一种与锂离子电池具有相似储能机理的电池，由于钠资源在地球上的储量丰富，其原料成本远低于锂，因此钠离子电池更有望满足未来对大规模储能器件的低成本需求，而作为钠离子电池的关键组成，钠正极材料的性能对钠离子电池的性能具有重要影响。Sodium-ion batteries are batteries with a similar energy storage mechanism to lithium-ion batteries. Since sodium resources are abundant on the earth, their raw material costs are much lower than lithium. Therefore, sodium-ion batteries are more likely to meet the future demand for large-scale energy storage devices. The demand for low cost, and as a key component of sodium-ion batteries, the performance of sodium cathode materials has an important impact on the performance of sodium-ion batteries.
其中，常见的层状钠正极材料易受到潮湿空气中水和CO2的影响，表面会产生大量残碱甚至发生相结构的变化，影响其加工性能及电化学性能。其中，对层状钠正极材料进行表面包覆改性是提高其空气稳定性的常用手段之一。常见的包覆层材料一般是可消耗残碱的材料，例如固态电解质材料，这类材料虽然可以降低初始残碱，但是由于包覆层自身缺乏对水和CO2的有效防御，使得在搁置过程中内核仍不断产生残碱；此外，绝大部分包覆层是不具备电化学活性的，例如固态电解质类材料，虽然能够提供Na+传输通道，但无法发生贡献克容量，容易降低正极材料的比容量。Among them, the common layered sodium cathode material is easily affected by water and CO2 in humid air. A large amount of residual alkali will be generated on the surface and even the phase structure may change, affecting its processing performance and electrochemical performance. Among them, surface coating modification of layered sodium cathode materials is one of the common methods to improve its air stability. Common coating layer materials are generally materials that can consume residual alkali, such as solid electrolyte materials. Although these materials can reduce the initial residual alkali, due to the lack of effective defense against water and CO 2 in the coating layer itself, it makes the The inner core still continuously produces residual alkali; in addition, most of the coating layers are not electrochemically active, such as solid electrolyte materials. Although they can provide Na + transmission channels, they cannot contribute to the gram capacity, which easily reduces the performance of the cathode material. Specific capacity.
因此，亟需开发一种能够兼顾良好的空气稳定性和电化学活性的包覆层材料以更好地提升层状钠正极材料的性能。Therefore, it is urgent to develop a coating material that can balance good air stability and electrochemical activity to better improve the performance of layered sodium cathode materials.
发明内容Contents of the invention
鉴于此，本申请实施例提供一种核壳型钠电池复合正极材料及其应用，以在不降低内核层状钠正极材料克容量的前提下，改善内核材料的空气稳定性，赋予该复合正极材料良好的储存和加工性能，以及良好电化学性能。In view of this, embodiments of the present application provide a core-shell sodium battery composite cathode material and its application, so as to improve the air stability of the core material without reducing the gram capacity of the core layered sodium cathode material, and endow the composite cathode with The material has good storage and processing properties, as well as good electrochemical properties.
本申请实施例第一方面提供一种钠电池复合正极材料，所述复合正极材料包括内核和包覆在所述内核上的包覆层，所述内核包括层状钠正极活性材料，所述包覆层的材料为脱钠电势高于所述内核的高电压型钠活性材料，所述高电压型钠活性材料包括通式NamEaJbGcOn所示的化合物、通式NadReQfFg所示的化合物及Na3V(PO3)3N中的至少一种；其中，0<m≤3，0<a≤3，0<n≤3，0<b≤3，0≤c≤3，E为可变价过渡金属元素，J包括Ga、Ge、As、Se、In、Sn、Sb、Te、Tl、B中的一种或多种，G包括Li、Mg、Zn、Ru、Ir中的一种或多种；0<d≤4，0<e≤4，0<f≤4，0<g≤3，R表示金属元素，Q表示聚阴离子基团，F表示氟元素。The first aspect of the embodiment of the present application provides a composite cathode material for a sodium battery. The composite cathode material includes an inner core and a coating layer covering the inner core. The inner core includes a layered sodium cathode active material, and the coating layer The material of the coating is a high-voltage sodium active material with a sodium removal potential higher than that of the core. The high-voltage sodium active material includes a compound represented by the general formula Na m E a J b G c On , the general formula Na d R e Q f F g and at least one of the compounds represented by Na 3 V(PO 3 ) 3 N; among them, 0<m≤3, 0<a≤3, 0<n≤3, 0<b ≤3, 0≤c≤3, E is a variable valence transition metal element, J includes one or more of Ga, Ge, As, Se, In, Sn, Sb, Te, Tl and B, G includes Li, One or more of Mg, Zn, Ru, Ir; 0<d≤4, 0<e≤4, 0<f≤4, 0<g≤3, R represents a metal element, Q represents a polyanionic group , F represents fluorine element.
上述复合正极材料中，在层状钠正极活性材料的表面设置上述包覆层，因含钠正极材料的空气稳定性与其充电电势是直接相关的，充电电势越高，空气稳定性越好，因此具有较高脱钠电势的上述包覆层在潮湿空气中的稳定性好，可减少内核材料与潮湿空气的直接接触，提高内核的空气稳定性，防止其发生结构变化及电化学性能下降；同时该包覆层具有钠电化学活性，能够在内核材料的充放电电压窗口内贡献容量，不会降低内核材料的克容量。In the above-mentioned composite cathode material, the above-mentioned coating layer is provided on the surface of the layered sodium cathode active material, because the air stability of the sodium-containing cathode material is directly related to its charging potential. The higher the charging potential, the better the air stability. Therefore, The above-mentioned coating layer with a higher desodium potential has good stability in humid air, which can reduce the direct contact between the core material and humid air, improve the air stability of the core, and prevent its structural changes and decrease in electrochemical performance; at the same time The coating layer has sodium electrochemical activity and can contribute capacity within the charge and discharge voltage window of the core material without reducing the gram capacity of the core material.
本申请实施方式中，所述高电压型钠活性材料比所述内核的脱钠电势高0.2V。In the embodiment of the present application, the high-voltage sodium active material has a sodium removal potential that is 0.2V higher than that of the core.
本申请实施方式中，所述高电压型钠活性材料的脱钠电势在3.3V以上。In the embodiment of the present application, the sodium removal potential of the high-voltage sodium active material is above 3.3V.
本申请实施方式中，在所述内核的工作电压范围内，所述包覆层材料的放电克容量为所述内核的放电克容量的50％-70％。这样，包覆层既贡献了一定容量，但又不会发生过度脱钠，且能降低内核在高电压窗口下的晶胞体积变化，减少内部过渡金属溶出。In the embodiment of the present application, within the operating voltage range of the core, the discharge gram capacity of the coating material is 50%-70% of the discharge gram capacity of the core. In this way, the cladding layer not only contributes a certain capacity but does not cause excessive desodiumization, it can also reduce the unit cell volume change of the core under the high voltage window and reduce the dissolution of internal transition metals.
本申请一些实施方式中，所述通式NadReQfFg所示的化合物包括Na2CoPO4F、Na2NiPO4F、Na2MnPO4F、Na2CrPO4F、NaVPO4F、Na3V2(PO4)2F3、Na3VCo(PO4)2F3、Na3VNi(PO4)2F3、Na3VMn(PO4)2F3、Na3VCr(PO4)2F3或Na3GaV(PO4)2F3。In some embodiments of the present application, the compounds represented by the general formula Na d Re Q f F g include Na 2 CoPO 4 F, Na 2 NiPO 4 F, Na 2 MnPO 4 F, Na 2 CrPO 4 F, NaVPO 4 F, Na 3 V 2 (PO 4 ) 2 F 3 , Na 3 VCo(PO 4 ) 2 F 3 , Na 3 VNi(PO 4 ) 2 F 3 , Na 3 VMn(PO 4 ) 2 F 3 , Na 3 VCr (PO 4 ) 2 F 3 or Na 3 GaV(PO 4 ) 2 F 3 .
本申请实施方式中，所述包覆层完全包覆所述内核的表面。这样可以避免内核材料未被包覆的区域成为水、CO2等的入侵位点，更好地提升内核的储存稳定性，及制浆过程中浆料的稳定性，进而保证其循环 稳定性和安全性能。In the embodiment of the present application, the coating layer completely covers the surface of the core. This can prevent the uncoated area of the core material from becoming an intrusion site for water, CO2, etc., better improve the storage stability of the core and the stability of the slurry during the pulping process, thereby ensuring its circulation. Stability and safety performance.
本申请实施方式中，所述包覆层的材料的质量是所述内核质量的0.1wt％-20wt％。这有助于形成合适厚度的包覆层，有效抑制空气中水、CO2对内核的侵蚀，保证内核材料的良好储存性或加工便利性。In the embodiment of the present application, the mass of the material of the coating layer is 0.1wt%-20wt% of the mass of the core. This helps to form a coating layer of appropriate thickness, effectively inhibits the erosion of the core by water and CO2 in the air, and ensures good storage or processing convenience of the core material.
本申请实施方式中，所述包覆层的厚度为0.5nm-200nm。合适厚度的包覆层能有效提高内核材料在空气中的稳定性，且不明显影响内核材料的比容量发挥。In the embodiment of the present application, the thickness of the coating layer is 0.5nm-200nm. A coating layer of appropriate thickness can effectively improve the stability of the core material in the air without significantly affecting the specific capacity of the core material.
本申请一些实施方式中，所述内核与所述包覆层之间还具有扩散层，所述扩散层包括所述内核的材料和所述包覆层的材料。扩散层的存在可以提高内核与包覆层之间的结合紧密性。In some embodiments of the present application, there is a diffusion layer between the core and the cladding layer, and the diffusion layer includes the material of the core and the material of the cladding layer. The presence of the diffusion layer can improve the tightness of the bond between the core and the cladding layer.
本申请实施例第二方面提供一种钠电池复合正极材料的制备方法，包括：The second aspect of the embodiments of the present application provides a method for preparing a composite cathode material for a sodium battery, including:
在层状钠正极活性材料的表面构建包覆层，得到复合正极材料；其中，所述包覆层的材料为脱钠电势高于所述层状钠正极活性材料的高电压型钠活性材料，所述高电压型钠活性材料包括通式NamEaJbGcOn所示的化合物、通式NadReQfFg所示的化合物及Na3V(PO3)3N中的至少一种；其中，0<m≤3，0<a≤3，0<n≤3，0<b≤3，0≤c≤3，E为可变价过渡金属元素，J包括Ga、Ge、As、Se、In、Sn、Sb、Te、Tl、Bi中的一种或多种，G包括Li、Mg、Zn、Ru、Ir中的一种或多种；0<d≤4，0<e≤4，0<f≤4，0<g≤3，R表示金属元素，Q表示聚阴离子基团，F表示氟元素。A coating layer is constructed on the surface of the layered sodium cathode active material to obtain a composite cathode material; wherein the material of the coating layer is a high-voltage sodium active material with a sodium removal potential higher than that of the layered sodium cathode active material, The high-voltage sodium active material includes a compound represented by the general formula Na m E a J b G c On , a compound represented by the general formula Na d Re Q f F g , and Na 3 V (PO 3 ) 3 N At least one of them; among them, 0<m≤3, 0<a≤3, 0<n≤3, 0<b≤3, 0≤c≤3, E is a variable valence transition metal element, and J includes Ga, One or more of Ge, As, Se, In, Sn, Sb, Te, Tl, Bi, G includes one or more of Li, Mg, Zn, Ru, Ir; 0<d≤4, 0<e≤4, 0<f≤4, 0<g≤3, R represents metal element, Q represents polyanionic group, and F represents fluorine element.
本申请实施例的复合正极材料的制备方法，流程简单，易于操作，适合于大规模生产。The preparation method of the composite cathode material in the embodiment of the present application has a simple process, is easy to operate, and is suitable for large-scale production.
本申请实施例第三方面还提供一种正极极片，所述正极极片包括本申请实施例第一方面所述的钠电池复合正极材料。The third aspect of the embodiment of the present application further provides a positive electrode plate, which includes the sodium battery composite positive electrode material described in the first aspect of the embodiment of the present application.
本申请实施例第四方面还提供一种钠二次电池，包括本申请实施例第三方面所述的正极极片。该钠二次电池具有良好的循环性能和安全性能，并保持高比容量特性。The fourth aspect of the embodiment of the present application also provides a sodium secondary battery, including the positive electrode sheet described in the third aspect of the embodiment of the present application. The sodium secondary battery has good cycle performance and safety performance, and maintains high specific capacity characteristics.
本申请实施例第五方面提供了一种电子设备，所述电子设备包括本申请第四方面所述的钠二次电池。该电子设备通过采用本申请实施例提供的钠二次电池供电，能够提升产品的使用体验和市场竞争力。The fifth aspect of the embodiment of the present application provides an electronic device, which includes the sodium secondary battery described in the fourth aspect of the present application. By using the sodium secondary battery provided by the embodiment of the present application for power supply, the electronic device can improve the product use experience and market competitiveness.
本申请实施例第六方面提供了一种储能***，所述储能***包括本申请实施例第四方面所述的钠二次电池。该储能***采用的钠二次电池具有良好的循环稳定性和安全性能。The sixth aspect of the embodiment of the present application provides an energy storage system, which includes the sodium secondary battery described in the fourth aspect of the embodiment of the present application. The sodium secondary battery used in this energy storage system has good cycle stability and safety performance.
附图说明Description of drawings
图1A为本申请实施例提供的钠电池复合正极材料的一种结构示意图。FIG. 1A is a schematic structural diagram of a sodium battery composite cathode material provided in an embodiment of the present application.
图1B为本申请实施例提供的钠电池复合正极材料的另一种结构示意图。Figure 1B is another structural schematic diagram of a sodium battery composite cathode material provided in an embodiment of the present application.
图2为本申请实施例提供的钠二次电池的结构示意图。Figure 2 is a schematic structural diagram of a sodium secondary battery provided by an embodiment of the present application.
图3为本申请实施例提供的电子设备的一种结构示意图。FIG. 3 is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application.
图4为本申请实施例提供的储能***的结构示意图。FIG. 4 is a schematic diagram of the structure of an energy storage system provided in an embodiment of the present application.
具体实施方式Detailed ways
下面将结合本申请实施例中的附图，对本申请实施例进行说明。The embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.
图1A为本申请一实施例提供的钠电池复合正极材料100的一种结构示意图，该复合正极材料100包括内核10和包覆在内核10上的包覆层20，内核10包括层状钠正极活性材料，包覆层20的材料为脱钠电势高于内核的高电压型钠活性材料，所述高电压型钠活性材料包括通式NamEaJbGcOn所示的化合物、通式NadReQfFg所示的化合物及Na3V(PO3)3N中的至少一种；其中，0<m≤3，0<a≤3，0<n≤3，0<b≤3，0≤c≤3，E为可变价过渡金属元素，J包括Ga(镓)、Ge(锗)、As(砷)、Se(硒)、In(铟)、Sn(锡)、Sb(锑)、Te(碲)、Tl(铊)、Bi(铋)中的一种或多种，G包括Li(锂)、Mg(镁)、Zn(锌)、Ru(钌)、Ir(铱)中的一种或多种；0<d≤4，0<e≤4，0<f≤4，0<g≤3，R表示金属元素，Q表示聚阴离子基团，F表示氟元素。Figure 1A is a schematic structural diagram of a sodium battery composite cathode material 100 provided by an embodiment of the present application. The composite cathode material 100 includes a core 10 and a coating layer 20 covering the core 10. The core 10 includes a layered sodium cathode. Active material, the material of the coating layer 20 is a high-voltage sodium active material with a sodium removal potential higher than that of the core. The high-voltage sodium active material includes a compound represented by the general formula Na m E a J b G c On , At least one of the compounds represented by the general formula Na d Re Q f F g and Na 3 V (PO 3 ) 3 N; wherein, 0<m≤3, 0<a≤3, 0<n≤3, 0<b≤3, 0≤c≤3, E is a variable valence transition metal element, J includes Ga (gallium), Ge (germanium), As (arsenic), Se (selenium), In (indium), Sn (tin ), one or more of Sb (antimony), Te (tellurium), Tl (thallium), Bi (bismuth), G includes Li (lithium), Mg (magnesium), Zn (zinc), Ru (ruthenium) , one or more of Ir (iridium); 0<d≤4, 0<e≤4, 0<f≤4, 0<g≤3, R represents a metal element, Q represents a polyanionic group, F Represents the element fluorine.
本申请中词语“层状钠正极活性材料”是指可通过脱/嵌钠离子进行能量存储的层状正极活性材料，或者，能可逆脱出和嵌入钠离子的层状正极活性材料。“高电压型钠活性材料”指脱钠电势高于内核材料的脱钠电势的钠活性材料。可以理解地，包覆层20的材料与内核10的材料是不同的钠电活性材料；包覆层的材料具有钠电化学活性且脱钠电势高于内核10。其中，包覆层20的材料可以包括至少一种如通式NamEaJbGcOn所示的化合物，或包括至少一种如通式NadReQfFg所示的化合物，或包括Na3V(PO3)3N，或者前述3类材料中两种以上的组合等。此外，NamEaJbGcOn、NadReQfFg、Na3V(PO3)3N中的Na为钠元素，NamEaJbGcOn中的O为氧元素，Na3V(PO3)3N是一具体化合物，其中的V是钒元素，N是氮元素，P是磷元素。The term "layered sodium cathode active material" in this application refers to a layered cathode active material that can store energy by desorbing and inserting sodium ions, or a layered cathode active material that can reversibly desorb and insert sodium ions. "High-voltage sodium active material" refers to a sodium active material whose sodium removal potential is higher than that of the core material. It can be understood that the material of the cladding layer 20 and the material of the core 10 are different sodium electroactive materials; the material of the cladding layer has sodium electrochemical activity and has a higher desodium potential than the core 10 . The material of the coating layer 20 may include at least one compound represented by the general formula Na m E a J b G c On , or at least one compound represented by the general formula Na d Re Q f F g Compounds, including Na 3 V(PO 3 ) 3 N, or a combination of two or more of the above three types of materials, etc. In addition, Na in Na m E a J b G c On , Na d R e Q f F g , Na 3 V(PO 3 ) 3 N is sodium element, and Na in Na m E a J b G c On O is oxygen element, Na 3 V(PO 3 ) 3 N is a specific compound, in which V is vanadium element, N is nitrogen element, and P is phosphorus element.
本申请实施例提供的钠电池复合正极材料100，通过在内核10的表面设置上述包覆层20，该含钠包覆层可通过包覆层原料与内核表面的残钠发生反应得到，有助于降低内核表面的残碱，降低材料的pH。 该包覆层20的材料的脱钠电势高，其在潮湿空气中的稳定性良好，对水和CO2的防御性好，其能对内核10起到持久保护作用，隔绝内核材料与潮湿空气的直接接触，防止因H2O、CO2分子的嵌入以及Na+/H+的交换而不断产生残碱，延长内核材料的稳定存放的时间，及防止潮解吸水导致的材料结构变化及性能下降；在正极浆料的搅拌制浆过程中，包覆层20也有助于稳定正极浆料，避免因内核材料的表面残碱含量高而易吸水变质所导致的浆料凝胶化、涂布困难等问题。此外，该包覆层20具有钠电化学活性，其能够在内核材料的充放电电压窗口内进行一定的脱/嵌Na+电化学反应，不会牺牲内核材料的克容量，甚至贡献额外的克容量。再者，包覆层20的脱钠电势高于内核10，其在高电压下具有较好的结构稳定性，当将上述复合材料在较高电压区间进行充电时，其可阻挡内核10的过渡金属离子从包覆层20溶出到电解液中，稳定内核的结构，避免其与电解液的副反应，提高循环稳定性。The sodium battery composite cathode material 100 provided in the embodiment of the present application is provided with the above-mentioned coating layer 20 on the surface of the core 10. The sodium-containing coating layer can be obtained by reacting the coating layer raw material with the residual sodium on the surface of the core, which helps It is used to reduce the residual alkali on the surface of the core and lower the pH of the material. The material of the coating layer 20 has a high sodium removal potential, good stability in humid air, and good defense against water and CO 2 . It can provide long-lasting protection to the core 10 and isolate the core material from the humid air. direct contact to prevent the continuous generation of residual alkali due to the embedding of H 2 O and CO 2 molecules and the exchange of Na + /H + , extend the stable storage time of the core material, and prevent material structural changes and performance degradation caused by deliquescence and water absorption. ; During the stirring and slurrying process of the positive electrode slurry, the coating layer 20 also helps to stabilize the positive electrode slurry and avoid gelation and coating difficulties of the slurry caused by high residual alkali content on the surface of the core material that easily absorbs water and deteriorates. And other issues. In addition, the coating layer 20 has sodium electrochemical activity, which can carry out a certain de/insertion Na + electrochemical reaction within the charge and discharge voltage window of the core material without sacrificing the gram capacity of the core material or even contributing additional grams. capacity. Furthermore, the desodium potential of the cladding layer 20 is higher than that of the core 10, and it has better structural stability under high voltage. When the above composite material is charged in a higher voltage range, it can block the transition of the core 10. Metal ions are dissolved from the coating layer 20 into the electrolyte, stabilizing the structure of the core, avoiding side reactions with the electrolyte, and improving cycle stability.
因此，上述包覆层20可在不降低内核10材料的克容量的前提下，改善内核10材料的空气稳定性，赋予该复合正极材料良好的储存和加工性能，以及良好的循环性能、高比容量等电化学性能，利于推动低成本钠电池的发展。Therefore, the above-mentioned coating layer 20 can improve the air stability of the core 10 material without reducing the gram capacity of the core 10 material, giving the composite cathode material good storage and processing properties, as well as good cycle performance and high ratio. Capacity and other electrochemical properties are conducive to promoting the development of low-cost sodium batteries.
本申请实施方式中，在内核10的工作电压范围内，包覆层20材料的放电克容量不超过内核10的放电克容量的80％，一般是50％-70％。这样，包覆层既贡献了容量，但又不会发生过渡脱钠，因此有助于保持包覆层的晶体结构稳定性，尤其是在高电压窗口下，有利于降低内核材料的晶胞体积变化，减少内部过渡金属溶出，提高循环稳定性。其中“内核的工作电压”是指介于内核材料的充电截止电压与放电截止电压的电压区间。上述复合正极活性材料一般在充电截止电压为2.0-4.3V的钠离子电池体系中应用，具体的充电截止电压可根据内核材料来调整。In the embodiment of the present application, within the operating voltage range of the core 10, the discharge gram capacity of the material of the cladding layer 20 does not exceed 80% of the discharge gram capacity of the core 10, which is generally 50%-70%. In this way, the cladding layer not only contributes to the capacity, but does not undergo excessive desodiumization, thus helping to maintain the stability of the crystal structure of the cladding layer, especially under the high voltage window, it is helpful to reduce the unit cell volume of the core material. changes, reducing the dissolution of internal transition metals and improving cycle stability. The "working voltage of the core" refers to the voltage range between the charge cut-off voltage and the discharge cut-off voltage of the core material. The above-mentioned composite cathode active materials are generally used in sodium-ion battery systems with a charge cut-off voltage of 2.0-4.3V. The specific charge cut-off voltage can be adjusted according to the core material.
本申请实施方式中，所述高电压型钠活性材料的脱钠电势比内核10的脱钠电势至少高0.2V。在一些实施方式中，高电压型钠活性材料比内核10的脱钠电势高0.3V，例如高0.3V-1V。具体可以是高0.32V、0.35V、0.4V、0.5V、0.6V、0.7V、0.8V、0.9V或0.95V等。In the embodiment of the present application, the sodium removal potential of the high-voltage sodium active material is at least 0.2V higher than the sodium removal potential of the core 10 . In some embodiments, the high voltage sodium active material has a desodium potential that is 0.3 V higher than the core 10 , for example, 0.3 V to 1 V higher. Specifically, it can be high 0.32V, 0.35V, 0.4V, 0.5V, 0.6V, 0.7V, 0.8V, 0.9V or 0.95V, etc.
本申请实施方式中，所述高电压型钠活性材料的脱钠电势在3.3V以上。具体地，通式NamEaJbGcOn所示化合物的脱钠电势在3.3V以上；聚阴离子型钠活性材料(NadReQfFg所示的化合物、Na3V(PO3)3N)的脱钠电势在3.3V以上，甚至在3.5V以上。In the embodiment of the present application, the sodium removal potential of the high-voltage sodium active material is above 3.3V. Specifically, the desodium potential of the compound represented by the general formula Na m E a J b G c On is above 3.3V; the compound represented by the polyanionic sodium active material (Na d Re Q f F g , Na 3 V The desodium potential of (PO 3 ) 3 N) is above 3.3V, even above 3.5V.
本申请中，通式NamEaJbGcOn所示的化合物是含钠及过渡金属元素的高电压氧化物，其中，该化合物中一定含有钠元素、氧元素、E元素及J元素，G元素是可选的，在某些情况下可以含有G元素。其中，Ga、Ge、As、Se、In、Sn、Sb、Te、Tl、Bi等J元素有助于构建蜂窝状结构的化合物NamEaJbGcOn，利于提升其脱钠电势，进而使其具有较高的空气稳定性，以便能较好地防护内核材料免受水、CO2等的侵害。在存在Li、Mg、Zn、Ru、Ir、等G元素时，有助于激发化合物NamEaJbGcOn中氧阴离子的氧化还原，提升其脱钠电势，进而进一步提升该类材料的空气稳定性。In this application, the compound represented by the general formula Na m E a J b G c On is a high voltage oxide containing sodium and transition metal elements. The compound must contain sodium element, oxygen element, E element and J element. Element, the G element is optional and can contain G elements in some cases. Among them, J elements such as Ga, Ge, As, Se, In, Sn, Sb, Te, Tl, and Bi help to build a honeycomb structure compound Na m E a J b G c O n and help improve its sodium removal potential. , thereby making it have higher air stability, so as to better protect the core material from water, CO 2 , etc. In the presence of G elements such as Li, Mg, Zn, Ru, Ir, etc., it helps to stimulate the redox of oxygen anions in the compound Na m E a J b G c On and increase its desodium potential, thereby further improving this type of Air stability of the material.
本申请实施方式中，所述E可以包括V(钒)、Cr(铬)、Fe(铁)、Co(钴)、Ni(镍)、Mn(锰)、Cu(铜)、Ti(钛)中的一种或多种。本申请一些实施方式中，所述G包括Mg、Ru、Ir中的一种或多种。当G为这些元素时，化合物NamEaJbGcOn的脱钠电势较高。In the embodiment of the present application, the E may include V (vanadium), Cr (chromium), Fe (iron), Co (cobalt), Ni (nickel), Mn (manganese), Cu (copper), Ti (titanium) one or more of them. In some embodiments of the present application, the G includes one or more of Mg, Ru, and Ir. When G is these elements, the desodium potential of the compound Na m E a J b G c On is higher.
本申请中，通式NadReQfFg所示的化合物及Na3V(PO3)3N均是钠的聚阴离子型化合物，它们的脱钠电势均较高，在空气中的稳定性较层状钠正极活性材料高，采用其作为层状钠正极活性材料的包覆材料，可以提升内核的空气稳定性，且该聚阴离子型化合物因具有钠电化学活性，采用其作为包覆材料，不会降低整体复合材料的比容量。其中，通式NadReQfFg所示的化合物同时含有聚阴离子基团Q和氟(F)元素。F元素的存在可以通过氟离子的强诱导效应来提高该聚阴离子型化合物的脱钠电势，使其具有较高的空气稳定性，便于对内核材料进行保护。In this application, the compound represented by the general formula Na d Re Q f F g and Na 3 V (PO 3 ) 3 N are both polyanionic compounds of sodium, and their desodium potentials are relatively high. It has higher stability than the layered sodium cathode active material. Using it as a coating material for the layered sodium cathode active material can improve the air stability of the core. Since this polyanionic compound has sodium electrochemical activity, it is used as a coating material. The cladding material will not reduce the specific capacity of the overall composite material. Among them, the compound represented by the general formula Na d Re Q f F g contains both the polyanionic group Q and the fluorine (F) element. The presence of F element can increase the desodium potential of the polyanionic compound through the strong induction effect of fluoride ions, making it have high air stability and facilitate the protection of the core material.
通式NadReQfFg中，R表示金属元素，这里的金属元素包括但不限于是过渡金属元素，和/或，主族金属元素，并以过渡金属元素较为常见。本申请实施方式中，R可以选自V(钒)、Cr(铬)、Fe(铁)、Co(钴)、Ni(镍)、Mn(锰)、Cu(铜)、Ti(钛)、Zr(锆)、Al(铝)等中的一种或多种，但不限于此。其中，聚阴离子基团Q可以选自磷的含氧酸根、硫的含氧酸根、硅的含氧酸根、硼的含氧酸根等中的一种或多种。具体地，磷的含氧酸根可以包括PO4 3-、PO3 3-、P2O7 4-、HPO4 2-、H2PO4 -等中的一种或多种；硫的含氧酸根可以包括SO4 2-、SO3 2-、HSO4 -等中的一种或多种；硅的含氧酸根可以包括SiO4 4-、SiO3 2-等中的一种或多种；硼的含氧酸根可以包括BO3 3-、BO2 -、B4O7 2-、B5O10 5-等中的一种或多种。In the general formula Na d R e Q f F g , R represents a metal element. The metal elements here include but are not limited to transition metal elements and/or main group metal elements, and transition metal elements are more common. In the embodiment of the present application, R can be selected from V (vanadium), Cr (chromium), Fe (iron), Co (cobalt), Ni (nickel), Mn (manganese), Cu (copper), Ti (titanium), One or more of Zr (zirconium), Al (aluminum), etc., but not limited to this. Among them, the polyanion group Q can be selected from one or more of phosphorus oxyacid radicals, sulfur oxyacid radicals, silicon oxyacid radicals, boron oxyacid radicals, and the like. Specifically, the oxygen-containing acid radical of phosphorus may include one or more of PO 4 3- , PO 3 3- , P 2 O 7 4- , HPO 4 2- , H 2 PO 4 - , etc.; the oxygen-containing acid radical of sulfur The acid radical may include one or more of SO 4 2- , SO 3 2- , HSO 4 - , etc.; the oxygen-containing acid radical of silicon may include one or more of SiO 4 4- , SiO 3 2- , etc.; The oxygen-containing acid radical of boron may include one or more of BO 3 3- , BO 2- , B 4 O 7 2- , B 5 O 10 5- , etc.
本申请一些实施方式中，通式NadReQfFg所示的化合物具体包括Na2CoPO4F、Na2NiPO4F、Na2MnPO4F、Na2CrPO4F、NaVPO4F、Na3V2(PO4)2F3、Na3VCo(PO4)2F3、Na3VNi(PO4)2F3、Na3VMn(PO4)2F3、Na3VCr(PO4)2F3或Na3GaV(PO4)2F3。这几种聚阴离子型化合物的脱钠电势较高，空气稳定性更好，它们的脱钠电势一般在 3.3V以上。In some embodiments of the present application, the compounds represented by the general formula Na d Re Q f F g specifically include Na 2 CoPO 4 F, Na 2 NiPO 4 F, Na 2 MnPO 4 F, Na 2 CrPO 4 F, and NaVPO 4 F , Na 3 V 2 (PO 4 ) 2 F 3 , Na 3 VCo(PO 4 ) 2 F 3 , Na 3 VNi(PO 4 ) 2 F 3 , Na 3 VMn(PO 4 ) 2 F 3 , Na 3 VCr( PO 4 ) 2 F 3 or Na 3 GaV(PO 4 ) 2 F 3 . These polyanionic compounds have higher sodium removal potentials and better air stability. Their sodium removal potentials are generally between 3.3V or above.
本申请实施方式中，包覆层材料在20℃下的钠离子电导率≥10-5S·cm-1。通过调控上述包覆层材料中元素的组成及其相对含量，可以获得所需良好离子电导率的包覆层，利于复合正极材料100整体的离子导电率提升，进而利于其倍率性能提升。In the embodiment of the present application, the sodium ion conductivity of the coating material at 20°C is ≥10 -5 S·cm -1 . By regulating the composition and relative content of the elements in the above-mentioned coating material, a coating layer with required good ionic conductivity can be obtained, which is beneficial to improving the overall ionic conductivity of the composite cathode material 100 and thus improving its rate performance.
一般地，层状钠正极活性材料是钠的过渡金属氧化物。本申请实施方式中，所述层状钠正极活性材料可以表示为NaxAyMzDuOv，其中，0<x≤12，0<y≤12，0≤z≤12，0≤u≤12，0<v≤12。A为可变价过渡金属元素，在一些实施方式中，A可以包括V(钒)、Cr(铬)、Fe(铁)、Co(钴)、Ni(镍)、Mn(锰)、Cu(铜)、Ti(钛)中的一种或多种。M为可对过渡金属元素进行取代/掺杂的元素，M可以包括Li(锂)、Al(铝)、Mg(镁)、Ca(钙)、K(钾)、Zn(锌)、Sn(锡)、等中的一种或多种；D包括C(碳)、P(磷)、Si(硅)、B(硼)、W(钨)中的一种或多种。Generally, the layered sodium cathode active material is a transition metal oxide of sodium. In the embodiment of the present application, the layered sodium cathode active material can be expressed as Na x A y M z D u O v , where 0<x≤12, 0<y≤12, 0≤z≤12, 0≤ u≤12, 0<v≤12. A is a variable valence transition metal element. In some embodiments, A may include V (vanadium), Cr (chromium), Fe (iron), Co (cobalt), Ni (nickel), Mn (manganese), Cu (copper ), one or more of Ti (titanium). M is an element that can substitute/dope transition metal elements. M can include Li (lithium), Al (aluminum), Mg (magnesium), Ca (calcium), K (potassium), Zn (zinc), Sn ( Tin), etc.; D includes one or more of C (carbon), P (phosphorus), Si (silicon), B (boron), W (tungsten).
本申请实施方式中，所述层状钠正极活性材料的粒径为50nm-30μm。层状钠正极活性材料的粒径较大，其比表面积不致过大，结构稳定性较高，但粒径不应过大以免增大钠离子在其中的扩散路径、劣化其倍率性能。在一些实施方式中，层状钠正极活性材料的粒径为500nm-20μm。合适粒径的层状钠正极活性材料可以兼顾较高的结构稳定性及较短的钠离子扩散路径。In the embodiment of the present application, the particle size of the layered sodium cathode active material is 50 nm-30 μm. The particle size of the layered sodium cathode active material is larger, its specific surface area should not be too large, and its structural stability is high. However, the particle size should not be too large to avoid increasing the diffusion path of sodium ions in it and degrading its rate performance. In some embodiments, the particle size of the layered sodium cathode active material ranges from 500 nm to 20 μm. Layered sodium cathode active materials with appropriate particle sizes can achieve both high structural stability and short sodium ion diffusion paths.
本申请实施方式中，如图1A所示，包覆层20完全包覆内核10的表面。这样可以避免层状钠正极活性材料未被包覆的区域成为水、CO2等的入侵位点，更好地提升内核的储存稳定性，及制浆过程中浆料的稳定性，进而保证其循环稳定性和安全性能。In the embodiment of the present application, as shown in FIG. 1A , the coating layer 20 completely covers the surface of the core 10 . This can prevent the uncoated area of the layered sodium cathode active material from becoming an invasion site for water, CO2, etc., better improve the storage stability of the core, and the stability of the slurry during the pulping process, thereby ensuring its Cycling stability and safety performance.
本申请实施方式中，包覆层20的厚度可以为0.5nm-200nm。合适厚度的包覆层能有效抑制层状钠正极活性材料与潮湿空气中水、CO2的反应，提高内核材料在空气中的稳定性，且不会因包覆层20的厚度过厚而影响内核材料的比容量发挥、降低钠电池的能量密度。具体地，包覆层20的厚度可以为1nm、2nm、5nm、10nm、20nm、30nm、40nm、50nm、60nm、80nm、90nm、100nm、120nm、150nm、180nm、200nm等。一些实施方式中，包覆层20的厚度可以是2nm-100nm。在另一些实施方式中，包覆层20的厚度为10nm-80nm。In the embodiment of the present application, the thickness of the coating layer 20 may be 0.5nm-200nm. A coating layer of appropriate thickness can effectively inhibit the reaction between the layered sodium cathode active material and water and CO 2 in humid air, improve the stability of the core material in the air, and will not be affected by the thickness of the coating layer 20 being too thick The specific capacity of the core material is exerted and the energy density of the sodium battery is reduced. Specifically, the thickness of the coating layer 20 may be 1 nm, 2 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 80 nm, 90 nm, 100 nm, 120 nm, 150 nm, 180 nm, 200 nm, etc. In some embodiments, the thickness of the cladding layer 20 may be 2 nm-100 nm. In other embodiments, the thickness of the cladding layer 20 is 10 nm-80 nm.
本申请实施方式中，所述复合正极材料中，包覆层材料的质量可以是内核材料(即，层状钠正极活性材料)质量的0.1wt％-20wt％。这有利于形成厚度合适、包覆完整度较高的包覆层20，有效抑制空气中水、CO2对内核的侵蚀，保证内核材料的良好储存性、加工便利性；在钠电池的循环过程中，该包覆层还能抑制内核与电解液之间的副反应，保证内核容量发挥。具体地，包覆层材料的质量可以是内核材料质量的0.2wt％、0.5wt％、1wt％、2wt％、5wt％、8wt％、10wt％、12wt％、15wt％或18wt％等。在一些实施方式中，包覆层材料的质量是内核材料质量的0.5wt％-20wt％；在另一些实施方式中，该质量占比为1wt％-15wt％。In the embodiment of the present application, in the composite cathode material, the mass of the coating layer material may be 0.1wt%-20wt% of the mass of the core material (ie, layered sodium cathode active material). This is conducive to forming a coating layer 20 with appropriate thickness and high coating integrity, effectively inhibits the erosion of the core by water and CO 2 in the air, and ensures good storage and processing convenience of the core material; during the cycle process of the sodium battery In addition, the coating layer can also inhibit side reactions between the core and the electrolyte to ensure that the capacity of the core is fully exerted. Specifically, the mass of the cladding material may be 0.2wt%, 0.5wt%, 1wt%, 2wt%, 5wt%, 8wt%, 10wt%, 12wt%, 15wt% or 18wt% of the core material mass, etc. In some embodiments, the mass of the cladding material is 0.5wt%-20wt% of the core material; in other embodiments, the mass ratio is 1wt%-15wt%.
本申请实施方式中，内核10的体相中可以掺杂有源自包覆层20的元素。其中，对于通式NamEaJbGcOn所示的包覆层材料，其掺杂到内核体相中的元素包括J元素、或J元素+G元素、或与内核中的A元素不同的E元素。对于通式NadReQfFg所示的包覆层材料，其掺杂到内核体相中的元素是金属元素R，一般是过渡金属元素。体相掺杂有助于提升内核材料的离子电导率和结构稳定性，从而显著提升复合正极材料100的倍率性能和循环稳定性。In the embodiment of the present application, the bulk phase of the core 10 may be doped with elements derived from the coating layer 20. Among them, for the coating layer material shown in the general formula NamEaJbGcOn , the element doped into the bulk phase of the core includes J element, or J element+ G element, or E element different from the A element in the core. For the coating layer material shown in the general formula NadReQfFg , the element doped into the bulk phase of the core is a metal element R, generally a transition metal element. Bulk phase doping helps to improve the ionic conductivity and structural stability of the core material, thereby significantly improving the rate performance and cycle stability of the composite positive electrode material 100.
本申请一些实施方式中，参见图1B，该复合正极材料100的内核10与包覆层20之间还具有扩散层12，该扩散层12包括内核10的材料(即，层状钠正极活性材料)和包覆层20的材料。该扩散层12可通过内核材料与包覆层材料的相互扩散形成，扩散层12与内核10可具有连续的层状钠正极活性材料体相，扩散层12可与包覆层20具有连续的包覆层材料的体相。其中，扩散层的存在可以提高内核10与包覆层20之间的结合紧密性，增强钠离子和电子在内核界面上的传输，并有效束缚钠正极活性材料的体相中过渡金属元素溶出，稳定其晶格结构，明显提升循环稳定性。In some embodiments of the present application, referring to FIG. 1B , a diffusion layer 12 is further provided between the core 10 and the coating layer 20 of the composite positive electrode material 100, and the diffusion layer 12 includes the material of the core 10 (i.e., the layered sodium positive electrode active material) and the material of the coating layer 20. The diffusion layer 12 may be formed by mutual diffusion of the core material and the coating layer material, and the diffusion layer 12 and the core 10 may have a continuous layered sodium positive electrode active material bulk phase, and the diffusion layer 12 and the coating layer 20 may have a continuous coating layer material bulk phase. Among them, the presence of the diffusion layer can improve the tightness of the bonding between the core 10 and the coating layer 20, enhance the transmission of sodium ions and electrons at the core interface, and effectively restrain the dissolution of transition metal elements in the bulk phase of the sodium positive electrode active material, stabilize its lattice structure, and significantly improve the cycle stability.
在一些实施方式中，在扩散层12中，包覆层材料扩散到内核材料的体相中，和/或表面处，形成J-O-A键或R-O-A键。其中，A为内核材料中的过渡金属元素，J为源自包覆层材料NamEaJbGcOn的元素，R为源自聚阴离子型包覆层材料的非钠金属元素。其中，J元素对应的离子，例如Sn4+、Sb5+，均属于d10电子结构，不会与O2p轨道发生杂化，因此有助于改变层状钠正极活性材料中氧原子的配位环境，增强A-O键的相互作用，因此可提升层状正极活性材料的晶格结构的稳定性，提升复合材料的电化学性能。In some embodiments, in the diffusion layer 12, the cladding material diffuses into the bulk phase of the core material, and/or at the surface, forming JOA bonds or ROA bonds. Among them, A is a transition metal element in the core material, J is an element derived from the cladding material Na m E a J b G c On , and R is a non-sodium metal element derived from the polyanionic cladding material. Among them, the ions corresponding to the J element, such as Sn 4+ and Sb 5+ , all belong to the d10 electronic structure and will not hybridize with the O 2p orbital. Therefore, they help change the coordination of oxygen atoms in the layered sodium cathode active material. The environment enhances the interaction of AO bonds, thereby improving the stability of the lattice structure of the layered cathode active material and improving the electrochemical performance of the composite material.
本申请实施方式中，扩散层12的厚度主要取决于包覆层材料、内核材料相互扩散的能力，特别是包覆层材料向内核10的扩散能力。为了较好地使内核10和包覆层20之间形成紧密的连接，扩散层12的厚度可以是0.1nm-20nm。具体可以是0.2nm、0.5nm、1nm、1.5nm、2nm、5nm、10nm、15nm等。一些实施例中，扩散层12的厚度为0.2nm-10nm；一些实施例中，扩散层12的厚度为0.2nm-5nm。 In the embodiment of the present application, the thickness of the diffusion layer 12 mainly depends on the mutual diffusion ability of the cladding material and the core material, especially the diffusion ability of the cladding material to the core 10 . In order to form a tight connection between the core 10 and the cladding layer 20, the thickness of the diffusion layer 12 may be 0.1 nm-20 nm. Specifically, it can be 0.2nm, 0.5nm, 1nm, 1.5nm, 2nm, 5nm, 10nm, 15nm, etc. In some embodiments, the thickness of the diffusion layer 12 is 0.2nm-10nm; in some embodiments, the thickness of the diffusion layer 12 is 0.2nm-5nm.
本申请实施例还提供一种上述复合正极材料的制备方法，该制备方法可包括：Embodiments of the present application also provide a method for preparing the above composite cathode material. The preparation method may include:
在层状钠正极活性材料的表面构建包覆层，得到复合正极材料；其中，所述包覆层的材料为脱钠电势高于所述层状钠正极活性材料的高电压型钠活性材料，所述高电压型钠活性材料包括通式NamEaJbGcOn所示化合物、通式NadReQfFg所示化合物及Na3V(PO3)3N中的至少一种；其中，0<m≤3，0<a≤3，0<n≤3，0<b≤3，0≤c≤3，E为可变价过渡金属元素，J包括Ga、Ge、As、Se、In、Sn、Sb、Te、Tl、Bi中的一种或多种，G包括Li、Mg、Zn、Ru、Ir中的一种或多种；0<d≤4，0<e≤4，0<f≤4，0<g≤3，R表示金属元素，Q表示聚阴离子基团，F为氟元素。A coating layer is constructed on the surface of the layered sodium cathode active material to obtain a composite cathode material; wherein the material of the coating layer is a high-voltage sodium active material with a sodium removal potential higher than that of the layered sodium cathode active material, The high-voltage sodium active material includes compounds represented by the general formula Na m E a J b G c On , compounds represented by the general formula Na d Re Q f F g , and Na 3 V (PO 3 ) 3 N. At least one; among them, 0<m≤3, 0<a≤3, 0<n≤3, 0<b≤3, 0≤c≤3, E is a variable valence transition metal element, and J includes Ga, Ge, One or more of As, Se, In, Sn, Sb, Te, Tl, Bi, G includes one or more of Li, Mg, Zn, Ru, Ir; 0<d≤4, 0< e≤4, 0<f≤4, 0<g≤3, R represents a metal element, Q represents a polyanion group, and F is a fluorine element.
其中，上述包覆层可通过层状钠正极活性材料与包覆层材料或合成包覆层材料的原料混合而构建得到。其中，包覆层的构建方法包括但不限于固相法、液相法及其他方法中的一种或多种。固相法可以是机械搅拌法、固相高能球磨法、机械融合法等，液相法可以是溶胶-凝胶法、水热/溶剂热包覆法、共沉淀包覆法、液相高能球磨法、涂覆法、喷雾干燥包覆法中的一种或多种。其他方法可以是选自原子层沉积法、化学气相沉积法、物理气相沉积法(如磁控溅射法、等离子溅射法、蒸镀法)、微波反应法等中的一种或多种。一般在混合之后，还需要进行高温烧结处理，以促进包覆层材料的结晶及增强其与钠正极活性材料之间的结合力。Wherein, the above-mentioned coating layer can be constructed by mixing the layered sodium positive electrode active material and the coating layer material or the raw material of the synthetic coating layer material. The construction method of the coating layer includes but is not limited to one or more of solid phase method, liquid phase method and other methods. The solid phase method can be mechanical stirring method, solid phase high energy ball milling method, mechanical fusion method, etc. The liquid phase method can be sol-gel method, hydrothermal/solvent thermal coating method, co-precipitation coating method, liquid phase high energy ball milling One or more of method, coating method, spray drying coating method. Other methods may be one or more selected from atomic layer deposition, chemical vapor deposition, physical vapor deposition (such as magnetron sputtering, plasma sputtering, evaporation), microwave reaction, etc. Generally, after mixing, a high-temperature sintering treatment is required to promote the crystallization of the coating material and enhance its bonding force with the sodium cathode active material.
本申请一些实施方式中，上述复合正极材料的制备方法可具体包括：In some embodiments of the present application, the preparation method of the above composite cathode material may specifically include:
S01，将层状钠正极活性材料与包覆层原料进行混合，得到第一复合材料；其中，所述包覆层原料为高电压型钠活性材料或合成所述高电压型钠活性材料的元素源，所述高电压型钠活性材料包括如通式NamEaJbGcOn所示化合物、通式NadReQfFg所示化合物、Na3V(PO3)3N中的至少一种；其中，0<m≤3，0<a≤3，0<n≤3，0<b≤3，0≤c≤3，E为可变价过渡金属元素，J包括Ga、Ge、As、Se、In、Sn、Sb、Te、Tl、Bi中的一种或多种，G包括Li、Mg、Zn、Ru、Ir中的一种或多种；0<d≤4，0<e≤4，0<f≤4，0<g≤3，R表示金属元素，Q表示聚阴离子基团，F为氟元素；S01, mix the layered sodium cathode active material and the coating layer raw material to obtain a first composite material; wherein the coating layer raw material is a high-voltage sodium active material or an element for synthesizing the high-voltage sodium active material Source, the high-voltage sodium active material includes compounds represented by the general formula Na m E a J b G c On , compounds represented by the general formula Na d Re Q f F g , Na 3 V (PO 3 ) 3 At least one of N; among them, 0<m≤3, 0<a≤3, 0<n≤3, 0<b≤3, 0≤c≤3, E is a variable valence transition metal element, and J includes Ga , one or more of Ge, As, Se, In, Sn, Sb, Te, Tl, Bi, G includes one or more of Li, Mg, Zn, Ru, Ir; 0<d≤4 , 0<e≤4, 0<f≤4, 0<g≤3, R represents the metal element, Q represents the polyanionic group, and F is the fluorine element;
S02，对所述第一复合材料进行烧结处理，得到复合正极材料；其中，所述复合正极材料包括内核和包覆在所述内核上的包覆层，所述内核包括层状正极活性材料，所述包覆层包括所述金属氧化物。S02, sintering the first composite material to obtain a composite positive electrode material; wherein the composite positive electrode material includes a core and a coating layer coated on the core, the core includes a layered positive electrode active material, and the coating layer includes the metal oxide.
步骤S01中，包覆所述包覆层材料的前驱体的方式包括上述原位反应包覆法，原位反应包覆法主要是指将合成包覆层材料的原料与正极活性材料进行混合，经原位反应制得包覆层材料前驱体的同时，实现对正极活性材料的包覆。该包覆层材料前驱体可在经步骤S02的烧结处理后，转变为包覆层材料。步骤S01中，所述混合的混合方法可以是前述固相法、液相法以及其他方法的一种或多种。In step S01, the method of coating the precursor of the coating layer material includes the above-mentioned in-situ reaction coating method. The in-situ reaction coating method mainly refers to mixing the raw materials for synthesizing the coating layer material and the cathode active material, While the coating layer material precursor is prepared through in-situ reaction, the positive electrode active material is coated. The cladding layer material precursor can be transformed into the cladding layer material after the sintering process in step S02. In step S01, the mixing method may be one or more of the aforementioned solid phase method, liquid phase method, and other methods.
在一些实施方式中，当步骤S01中所用的包覆层原料为高电压型钠活性材料的各元素源时，经过步骤S01的混合处理后，可在制得包覆层材料前驱体的同时，实现对层状钠正极活性材料的包覆。该包覆层材料前驱体可在经步骤S02的烧结处理后，转变为包覆层材料。In some embodiments, when the coating layer raw materials used in step S01 are various element sources of high-voltage sodium active materials, after the mixing process in step S01, while preparing the coating layer material precursor, Realize coating of layered sodium cathode active material. The cladding layer material precursor can be transformed into the cladding layer material after the sintering process in step S02.
对于通式为NadReQfFg的包覆层材料来说，其包覆层原料(即，合成其所需的各原料源)具体包括钠源、金属R源(即，包含金属元素R的原料)、聚阴离子基团源及氟源。其中，钠源可以是Na的氢氧化物、碳酸盐、硝酸盐、草酸盐、醋酸盐、硫酸盐、磷酸盐、含氟盐中的一种或多种。类似地，金属R源具体可包括V、Fe、Cr、Mn、Co、Ni、Cu、Ti、Zr、Al等的氧化物、氢氧化物、碳酸盐、硝酸盐、草酸盐、醋酸盐、硫酸盐、磷酸盐、含氟盐中的一种或多种。氟源可以是NH4F、NH4HF2、NaF等中的一种或多种。聚阴离子基团(Q)源包括P的含氧酸根源、S的含氧酸根、Si的含氧酸根源、B的含氧酸根源等的一种或多种，其中P的含氧酸根源可选自NH4H2PO4、(NH4)2HPO4、(NH4)3PO4、H3PO4、NH4H2PO3、(NH4)2HPO3、H3PO3、(NH4)4P2O7中的一种或多种；S的含氧酸根可以包括Na2SO4、NaHSO4、Na2SO3中的一种或多种；Si的含氧酸根源选自Na2O.nSiO2、H2SiO3、C8H20O4Si(TEOS)中的一种或多种；B的含氧酸根源选自H3BO3、HBO2、Na2B4O7的一种或多种；钨的含氧酸根源选自WO3、H2WO4、(NH4)2WO4中的一种或多种。此外，合成Na3V(PO3)3N的原料源与通式为NadReQfFg的聚阴离子型化合物类似，可包括钠源、钒源、磷源及氮源。其中，这些原料源可以和二为一，或者合多为一，例如钠源和磷源可以是同一材料。For the cladding material with the general formula Na d Re Q f F g , the cladding raw materials (i.e., the raw material sources required to synthesize it) specifically include sodium sources, metal R sources (i.e., containing metal Raw material of element R), polyanionic group source and fluorine source. The sodium source may be one or more of Na hydroxide, carbonate, nitrate, oxalate, acetate, sulfate, phosphate, and fluorine-containing salt. Similarly, the metal R source may specifically include oxides, hydroxides, carbonates, nitrates, oxalates, acetic acid, etc. of V, Fe, Cr, Mn, Co, Ni, Cu, Ti, Zr, Al, etc. One or more of salts, sulfates, phosphates, and fluoride-containing salts. The fluorine source may be one or more of NH 4 F, NH 4 HF 2 , NaF, etc. The source of the polyanion group (Q) includes one or more of the oxygen-containing acid radicals of P, the oxygen-containing acid radicals of S, the oxygen-containing acid radicals of Si, the oxygen-containing acid radicals of B, etc., wherein the oxygen-containing acid radicals of P Can be selected from NH 4 H 2 PO 4 , (NH 4 ) 2 HPO 4 , (NH 4 ) 3 PO 4 , H 3 PO 4 , NH 4 H 2 PO 3 , (NH 4 ) 2 HPO 3 , H 3 PO 3 , one or more of (NH 4 ) 4 P 2 O 7 ; the oxygen-containing acid radical of S may include one or more of Na 2 SO 4 , NaHSO 4 , Na 2 SO 3 ; the oxygen-containing acid of Si The source is selected from one or more of Na 2 O.nSiO 2 , H 2 SiO 3 , C 8 H 20 O 4 Si (TEOS); the oxygen-containing acid source of B is selected from H 3 BO 3 , HBO 2 , Na One or more of 2 B 4 O 7 ; the oxygen-containing acid source of tungsten is selected from one or more of WO 3 , H 2 WO 4 , (NH 4 ) 2 WO 4 . In addition, the source of raw materials for synthesizing Na 3 V(PO 3 ) 3 N is similar to the polyanionic compound with the general formula Na d Re Q f F g , and may include a sodium source, a vanadium source, a phosphorus source and a nitrogen source. Among them, these raw material sources can be two into one, or more than one into one. For example, the sodium source and the phosphorus source can be the same material.
对于通式为NamEaJbGcOn的包覆层材料来说，其包覆层原料具体包括钠源、元素E源、J源及可选的G元素源。E、J、G元素的原料可以是选自对应元素的氧化物、氢氧化物、碳酸盐、硝酸盐、草酸盐、醋酸盐、硫酸盐、磷酸盐、含氟盐等，且最好含有氧。此外，对于通式为NamEaJbGcOn的包覆层材料，可以采用溶胶-凝胶法构建其前驱体(例如是其氢氧化物)，具体包括：将锂源、元素E的原料、元素J的原料及可选的元素G的原料与层状钠正极活性材料加入到溶剂中，在搅拌条件下进行反应，之后蒸干溶剂，在层状钠正极活性材料表面形成包覆层前驱体材料。其中，搅拌反应的时间可以是20-60min。所用溶剂可以包括水、乙醇、丙酮等中的一种或多种。蒸干溶剂采用的加热温度为60℃-100℃。 For the coating material with the general formula Na m E a J b G c On , the coating raw materials specifically include sodium source, element E source, J source and optional G element source. The raw materials of E, J, and G elements can be selected from oxides, hydroxides, carbonates, nitrates, oxalates, acetates, sulfates, phosphates, fluorine-containing salts, etc. of the corresponding elements, and the final Very oxygenated. In addition, for the coating layer material with the general formula Na m E a J b G c On , the sol-gel method can be used to construct its precursor (for example, its hydroxide), which specifically includes: combining lithium source, elements The raw materials of E, the raw materials of element J and the optional raw materials of element G are added to the solvent with the layered sodium cathode active material, and the reaction is carried out under stirring conditions. The solvent is then evaporated to dryness, and a package is formed on the surface of the layered sodium cathode active material. Cladding precursor material. The stirring reaction time can be 20-60 minutes. The solvent used may include one or more of water, ethanol, acetone, etc. The heating temperature used to evaporate the solvent is 60°C-100°C.
本申请一些实施方式中，在步骤S01中，所用包覆层原料若为合成高电压型钠活性材料的各元素源，则所用元素源可以不含钠源，最终所得包覆层中的钠元素可源自层状钠正极活性材料，例如具体源自其表面的残钠，即，包覆层可通过消耗内核表面的残钠反应得到。In some embodiments of the present application, in step S01, if the raw materials used for the coating layer are sources of elements for synthesizing high-voltage sodium active materials, the element sources used may not contain sodium sources, and the sodium element in the final coating layer It can be derived from the layered sodium cathode active material, for example specifically from the residual sodium on its surface, that is, the coating layer can be obtained by consuming the residual sodium on the surface of the core.
在一些实施例中，可以采用固相法进行步骤S01的所述混合。该固相法可以具体是机械搅拌法、高能球磨法、机械融合法等。其中，固相法中的固相混合时间为2h-24h，进一步可以是10-24h。在一具体实施例中，可具体通过球磨法实现该固化混合，进而实现核壳型复合材料的便捷制备。其中，球磨的转速可以是100-700r/min，例如可以是200r/min、300r/min、400r/min、450r/min、500r/min、550r/min、600r/min、650r/min等。在一些实施方式中，球磨的转速可以是400-700r/min。In some embodiments, a solid-phase method may be used to perform the mixing of step S01. The solid phase method can specifically be a mechanical stirring method, a high-energy ball milling method, a mechanical fusion method, etc. Among them, the solid phase mixing time in the solid phase method is 2h-24h, and may further be 10-24h. In a specific embodiment, the solidification mixing can be achieved specifically through a ball milling method, thereby realizing the convenient preparation of core-shell composite materials. Among them, the rotation speed of the ball mill can be 100-700r/min, for example, it can be 200r/min, 300r/min, 400r/min, 450r/min, 500r/min, 550r/min, 600r/min, 650r/min, etc. In some embodiments, the rotation speed of the ball mill can be 400-700 r/min.
在另一些实施方式中，当步骤S01中，所用的包覆层原料为所需的高电压型钠活性材料时，经过步骤S01的混合处理后，可在层状钠正极活性材料的表面包覆上所述高电压型钠活性材料。In other embodiments, when the coating layer raw material used in step S01 is the required high-voltage sodium active material, after the mixing process in step S01, the surface of the layered sodium cathode active material can be coated The above-mentioned high-voltage sodium active material.
当步骤S01中所用包覆层原料为高电压型钠活性材料时，经过步骤S02的烧结处理，可以提升提高内核层状钠正极活性材料与包覆层之间的结合力；当步骤S01中所用包覆层原料为合成高电压型钠活性材料的原料源时，经过步骤S02的烧结处理，可以在获得包覆层材料-高电压型钠活性材料的同时，实现对内核的紧密包覆。When the coating layer raw material used in step S01 is a high-voltage sodium active material, the binding force between the core layered sodium cathode active material and the coating layer can be improved through the sintering process in step S02; when the coating layer used in step S01 When the raw material of the coating layer is the raw material source for synthesizing the high-voltage sodium active material, through the sintering process in step S02, the coating layer material-the high-voltage sodium active material can be obtained while tightly coating the core.
在一些实施方式中，对第一复合材料进行烧结处理，还可在所述内核与所述包覆层之间形成扩散层，扩散层包括内核材料和包覆层材料。其中，烧结处理除了可以提高内核层状钠正极活性材料与包覆层之间的结合力外，还可促进内核、包覆层进行互扩散形成一扩散层，增强钠离子和电子在二者界面上的传输。In some embodiments, the first composite material is sintered, and a diffusion layer may be formed between the core and the cladding layer. The diffusion layer includes a core material and a cladding layer material. Among them, the sintering treatment can not only improve the binding force between the core layered sodium cathode active material and the coating layer, but also promote the interdiffusion of the core and the coating layer to form a diffusion layer, enhancing the interaction between sodium ions and electrons at the interface between the two. transmission on.
步骤S02的烧结处理可以在氧气、空气、氮气、氩气、氦气等气氛下进行。为了保证包覆层形成所需的晶相结构，确保内核与包覆层的结合紧密性，及实现包覆层的厚度均匀且连续，本申请实施例对烧结过程中的烧结温度和保温时间进行了设定，其中烧结处理中的烧结温度可以为200-900℃，烧结保温时间可以是0.5h-12h。示例性的，烧结温度具体可以是250、300、400、500、600、650、700、800或850℃等，在一些实施方式中，烧结温度可以是300-700℃。烧结保温时间具体可以是1h、2h、4h、5h、6h、7h、8h、9h、10h或11h等。此外，在烧结处理过程的升温速率可以为0.5-20℃/min，例如是1、2、3、5、8、10、15℃/min等。在一些实施方式中，该升温速率可以是0.5-5℃/min。这样可以避免升温速率过快而在各相之间的界面上产生较大的应力。The sintering process in step S02 can be performed in an atmosphere such as oxygen, air, nitrogen, argon, helium, etc. In order to ensure the crystal phase structure required for the formation of the cladding layer, ensure the tightness of the combination between the core and the cladding layer, and achieve uniform and continuous thickness of the cladding layer, the sintering temperature and holding time during the sintering process are measured in the embodiments of this application. The sintering temperature in the sintering process can be 200-900°C, and the sintering holding time can be 0.5h-12h. For example, the sintering temperature may be 250, 300, 400, 500, 600, 650, 700, 800 or 850°C, etc. In some embodiments, the sintering temperature may be 300-700°C. The sintering heat preservation time can be specifically 1h, 2h, 4h, 5h, 6h, 7h, 8h, 9h, 10h or 11h, etc. In addition, the temperature rise rate during the sintering process can be 0.5-20°C/min, such as 1, 2, 3, 5, 8, 10, 15°C/min, etc. In some embodiments, the heating rate may be 0.5-5°C/min. This can prevent the heating rate from being too fast and causing large stress on the interface between the phases.
烧结完成后，自然冷却后收集粉末，即得到复合正极材料。在一些实施方式中，还可以将烧结后收集得到的粉末进行破碎细化处理，以得到所需粒径的复合正极材料。After sintering is completed, the powder is collected after natural cooling to obtain the composite cathode material. In some embodiments, the powder collected after sintering can also be crushed and refined to obtain a composite cathode material with a desired particle size.
本申请实施例提供的上述复合正极材料的制备方法，该制备方法原料成本低、流程简单，易于操作，适合于大规模生产。The preparation method of the composite cathode material provided by the embodiments of the present application has low raw material cost, simple process, easy operation, and is suitable for large-scale production.
本申请实施例还提供一种用于钠电池的正极极片，该正极极片包括本申请实施例上述的钠电池复合正极材料。本申请一些实施方式中，正极极片包括正极集流体和设置在正极集流体上的正极材料层，正极材料层包括本申请实施例上述的上述复合正极材料。正极材料层还可以包括粘结剂和导电剂。一些实施例中，正极材料层中还可以包括不同于其他正极活性材料。An embodiment of the present application also provides a positive electrode sheet for a sodium battery, which includes the sodium battery composite positive electrode material described above in the embodiment of the present application. In some embodiments of the present application, the positive electrode sheet includes a positive electrode current collector and a positive electrode material layer disposed on the positive electrode current collector. The positive electrode material layer includes the composite positive electrode material described in the embodiments of the present application. The cathode material layer may also include a binder and a conductive agent. In some embodiments, the cathode material layer may also include other cathode active materials.
正极集流体为钠电池领域的常规选择，例如可以是铝箔、涂炭铝箔、镀铝聚合物膜。粘结剂可以具体包括但不限于聚四氟乙烯(PTFE)、聚偏氟乙烯(PVDF)、聚乙烯醇(PVA)、聚酰亚胺(PI)、聚丙烯酸(PAA)、聚丙烯酸酯、聚丙烯酰胺(PAM)、羧甲基纤维素(CMC)、丁苯橡胶(SBR)和海藻酸钠等中的一种或多种。导电剂可以具体包括但不限于乙炔黑、科琴黑、Super P导电炭黑、石墨、石墨烯、碳纳米管、碳纤维、无定形碳等中的一种或多种。The positive electrode current collector is a common choice in the field of sodium batteries, and can be, for example, aluminum foil, carbon-coated aluminum foil, or aluminum-plated polymer film. The binder may specifically include, but is not limited to, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), polyimide (PI), polyacrylic acid (PAA), polyacrylate, One or more of polyacrylamide (PAM), carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), sodium alginate, etc. The conductive agent may specifically include, but is not limited to, one or more of acetylene black, Ketjen black, Super P conductive carbon black, graphite, graphene, carbon nanotubes, carbon fiber, amorphous carbon, etc.
该正极极片的制备方法可包括：将本申请实施的上述复合正极材料、导电剂、粘结剂与溶剂混合，制成正极浆料；将该正极浆料涂布在正极集流体上，干燥后进行辊压，得到正极极片。The preparation method of the positive electrode sheet may include: mixing the above-mentioned composite positive electrode materials, conductive agents, binders and solvents implemented in this application to prepare positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and drying Then roll it to obtain the positive electrode piece.
参见图2，本申请实施例还提供一种钠二次电池200，其包括上述正极极片。该钠二次电池200包括正极201、负极202、设置于正极201与负极202之间的隔膜203、电解液204，以及相应的连通辅件和回路，其中正极201包括本申请实施例上述的正极极片。Referring to Figure 2, an embodiment of the present application also provides a sodium secondary battery 200, which includes the above-mentioned positive electrode plate. The sodium secondary battery 200 includes a positive electrode 201, a negative electrode 202, a separator 203 disposed between the positive electrode 201 and the negative electrode 202, an electrolyte 204, and corresponding connecting accessories and circuits, wherein the positive electrode 201 includes the positive electrode described in the embodiment of the present application. Extreme piece.
在钠二次电池的充电过程中，在外加电路的作用下，钠离子从正极201脱出经过电解液204、隔膜203迁移到负极202，同时电子经外电路从正极流向负极，电能被储存；放电过程与充电相反，钠离子从负极202脱出并经电解液204、隔膜203返回正极201，同时电子经外电路从负极迁移到正极，对外释放电能。由于该钠二次电池使用了上述复合正极材料100，在其工作电压范围内具有良好的循环稳定性、安全性能及倍率性能。During the charging process of the sodium secondary battery, under the action of the external circuit, sodium ions escape from the positive electrode 201 and migrate to the negative electrode 202 through the electrolyte 204 and the diaphragm 203, while electrons flow from the positive electrode to the negative electrode through the external circuit, and electrical energy is stored; the discharge process is opposite to the charging process, sodium ions escape from the negative electrode 202 and return to the positive electrode 201 through the electrolyte 204 and the diaphragm 203, while electrons migrate from the negative electrode to the positive electrode through the external circuit, releasing electrical energy to the outside. Since the sodium secondary battery uses the above-mentioned composite positive electrode material 100, it has good cycle stability, safety performance and rate performance within its operating voltage range.
负极202可以包括负极集流体和设置在负极集流体上的负极材料层，负极材料层包括负极活性材料、 粘结剂和可选的导电剂。其中，负极集流体包括但不仅限于金属箔材、合金箔材或镀金属膜，其表面可被蚀刻处理或粗化处理，以形成次级结构，便于和负极材料层形成有效接触。示例性的金属箔材可以为铜箔、涂炭铜箔或镀铜膜，示例性的合金箔材可以是不锈钢箔、铜合金箔等。其中，负极活性材料包括但不限于碳基材料、硅基材料、锡基材料、磷基材料中的一种或多种。其中，碳基材料可包括非石墨化炭(软碳、硬碳、中间相碳微球等)、石墨(如天然石墨、人造石墨)；硅基材料可包括单质硅、硅基合金、硅氧化物和硅碳复合材料等中的一种或多种；锡基材料可包括单质锡、锡合金、锡氧化物、锡碳复合材料等中的一种或多种；磷基材料可包括磷单质(如黑磷)、磷碳复合材料等。隔膜203可以是聚合物隔膜、无纺布等，包括但不限于单层PP(聚丙烯)、单层PE(聚乙烯)、双层PP/PE、双层PP/PP和三层PP/PE/PP等隔膜。电解液204包括锂盐和非水有机溶剂，非水有机溶剂可包括碳酸酯类溶剂、羧酸酯类溶剂、醚类溶剂中的一种或多种。The negative electrode 202 may include a negative electrode current collector and a negative electrode material layer disposed on the negative electrode current collector. The negative electrode material layer includes a negative electrode active material, Adhesive and optional conductive agent. Among them, the negative electrode current collector includes but is not limited to metal foil, alloy foil or metallized film, and its surface can be etched or roughened to form a secondary structure to facilitate effective contact with the negative electrode material layer. Exemplary metal foils may be copper foil, carbon-coated copper foil or copper-plated film, and exemplary alloy foils may be stainless steel foils, copper alloy foils, etc. The negative active material includes, but is not limited to, one or more of carbon-based materials, silicon-based materials, tin-based materials, and phosphorus-based materials. Among them, carbon-based materials can include non-graphitized carbon (soft carbon, hard carbon, mesocarbon microspheres, etc.), graphite (such as natural graphite, artificial graphite); silicon-based materials can include elemental silicon, silicon-based alloys, silicon oxide One or more of materials and silicon-carbon composite materials; tin-based materials can include one or more of elemental tin, tin alloys, tin oxides, tin-carbon composite materials, etc.; phosphorus-based materials can include elemental phosphorus (such as black phosphorus), phosphorus carbon composite materials, etc. The separator 203 can be a polymer separator, non-woven fabric, etc., including but not limited to single-layer PP (polypropylene), single-layer PE (polyethylene), double-layer PP/PE, double-layer PP/PP and three-layer PP/PE. /PP and other separators. The electrolyte 204 includes a lithium salt and a non-aqueous organic solvent. The non-aqueous organic solvent may include one or more of carbonate solvents, carboxylate solvents, and ether solvents.
本申请实施例的钠二次电池可用于终端消费产品，如手机、平板电脑、移动电源、便携机、笔记本电脑、数码相机以及其它可穿戴电子设备或可移动的电子设备，如无人机、电动自行车、电动汽车等产品，以提高产品的性能。The sodium secondary battery of the embodiment of the present application can be used in terminal consumer products, such as mobile phones, tablet computers, mobile power supplies, portable machines, notebook computers, digital cameras, and other wearable electronic devices or movable electronic devices, such as drones, Products such as electric bicycles and electric vehicles to improve product performance.
本申请实施例还提供一种包含有电子设备，该电子设备包括本申请实施例上述提供的钠二次电池200。An embodiment of the present application also provides an electronic device including the sodium secondary battery 200 provided in the embodiment of the present application.
该电子设备可以是包括各种消费类电子产品，如手机、平板电脑、笔记本电脑、移动电源、便携机、以及其它可穿戴或可移动的电子设备、电视机、影碟机、录像机、摄录机、收音机、收录机、组合音响、电唱机、激光唱机、家庭办公设备、家用电子保健设备，还可以是汽车、储能设备等电子产品。The electronic device may include various consumer electronic products, such as mobile phones, tablet computers, notebook computers, mobile power supplies, portable machines, and other wearable or removable electronic devices, televisions, DVD players, video recorders, and camcorders. , radios, cassette players, combo stereos, record players, compact disc players, home office equipment, home electronic health care equipment, and also electronic products such as automobiles and energy storage equipment.
在一些实施方式中，参见图3，电子设备300包括壳体301和容纳于壳体301内的电子元器件(图3中未示出)和电池302，电池302为电子设备300供电，电池302包括本申请实施例上述的钠二次电池200。壳体301可包括组装在终端前侧的前盖和组装在后侧的后壳，电池302可固定在后壳内侧。In some embodiments, referring to FIG. 3 , the electronic device 300 includes a housing 301 and electronic components (not shown in FIG. 3 ) accommodated in the housing 301 and a battery 302 . The battery 302 supplies power to the electronic device 300 . The battery 302 Including the sodium secondary battery 200 described in the embodiment of the present application. The housing 301 may include a front cover assembled on the front side of the terminal and a rear shell assembled on the rear side, and the battery 302 may be fixed inside the rear shell.
本申请实施例提供的电子设备通过采用本申请实施例提供的复合正极材料作为电池的正极活性材料，能够满足各类电子产品对电池的良好热稳定性、长循环寿命、高能量密度的需求，提升电子产品的使用体验和市场竞争力。The electronic device provided in the embodiment of the present application adopts the composite positive electrode material provided in the embodiment of the present application as the positive electrode active material of the battery, which can meet the requirements of various electronic products for good thermal stability, long cycle life, and high energy density of the battery, thereby improving the user experience and market competitiveness of the electronic products.
参见图4，本申请实施例还提供一种储能***400，储能***400包括电池组401和与电池组401电连接的电池管理***402，电池组401包括本申请实施例上述提供的钠二次电池200。Referring to Figure 4, an embodiment of the present application also provides an energy storage system 400. The energy storage system 400 includes a battery pack 401 and a battery management system 402 electrically connected to the battery pack 401. The battery pack 401 includes the sodium chloride provided in the embodiment of the present application. Secondary battery 200.
本申请中，“和/或”，描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，及单独存在B的情况。本申请中，“至少一种”是指一种或者多种；“多种”是指两种以上(即，大于或等于两种)。“至少一个”、“多个”的含义与之类似。In this application, "and/or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and/or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In this application, "at least one" means one or more; "multiple" means more than two (i.e., greater than or equal to two). The meanings of "at least one" and "multiple" are similar.
下面分多个实施例对本申请实施例进行进一步的说明。The embodiments of the present application will be further described below in multiple embodiments.
实施例1Example 1
一种钠电池复合正极材料的制备，包括以下步骤：Preparation of a sodium battery composite cathode material, including the following steps:
提供内核材料—层状钠正极活性材料NaNi1/3Fe1/3Mn1/3O2(平均粒径为3-10μm)，将100g的该内核材料与0.36g的氧化锑(Sb2O3)粉末、1.25g的四水乙酸镍(Ni(CH3COO)2·4H2O)混合，并在300rpm的转速下球磨10h，将球磨后物料置于管式炉中进行烧结，烧结条件为：从室温以5℃/min的升温速率升至烧结温度800℃，在该温度下保温烧结3h；之后自然冷却至室温，得到复合正极材料。该复合正极材料包括NaNi1/3Fe1/3Mn1/3O2内核，和形成在内核表面的NamNi2/3Sb1/3O2包覆层，m在0.5-1.0之间。该复合正极材料可记作NaNi1/3Fe1/3Mn1/3O2@NamNi2/3Sb1/3O2。其中，包覆层的厚度为10nm，包覆层的质量占内核质量的1.0％。Provide core material - layered sodium cathode active material NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (average particle size is 3-10 μm), mix 100g of this core material with 0.36g of antimony oxide (Sb 2 O 3 ) Powder and 1.25g of nickel acetate tetrahydrate (Ni(CH 3 COO) 2 ·4H 2 O) are mixed and ball-milled at 300 rpm for 10 hours. The ball-milled material is placed in a tube furnace for sintering. Sintering conditions The method is: from room temperature to a sintering temperature of 800°C at a heating rate of 5°C/min, and then kept and sintered at this temperature for 3 hours; then naturally cooled to room temperature to obtain a composite cathode material. The composite cathode material includes a NaNi 1/3 Fe 1/3 Mn 1/3 O 2 core and a Na m Ni 2/3 Sb 1/3 O 2 coating layer formed on the surface of the core, with m between 0.5-1.0 . The composite cathode material can be recorded as NaNi 1/3 Fe 1/3 Mn 1/3 O 2 @Nam Ni 2/3 Sb 1/3 O 2 . Among them, the thickness of the cladding layer is 10nm, and the mass of the cladding layer accounts for 1.0% of the core mass.
钠二次电池的制备：Preparation of sodium secondary battery:
将实施例1的复合正极材料与导电剂Super P、粘结剂PVDF按照92：4：4的质量比混合，加入适量的N-甲基吡咯烷酮(NMP)，研磨均匀后，得到正极浆料；将该浆料均匀涂在铝箔上，烘干后经辊压得到极片。以上述极片为正极，以金属钠片为负极，在氩气保护的手套箱中组装成扣式电池。后续可对该扣式电池进行电化学性能测试。Mix the composite cathode material of Example 1 with the conductive agent Super P and the binder PVDF in a mass ratio of 92:4:4, add an appropriate amount of N-methylpyrrolidone (NMP), and grind evenly to obtain a cathode slurry; The slurry is evenly coated on the aluminum foil, dried and rolled to obtain the pole piece. Use the above-mentioned pole piece as the positive electrode and the metal sodium piece as the negative electrode, and assemble a button battery in an argon-protected glove box. The electrochemical performance test of the button cell can be carried out later.
实施例2Example 2
一种复合正极材料的制备，包括以下步骤：The preparation of a composite cathode material includes the following steps:
提供内核材料—层状钠正极活性材料NaNi1/3Fe1/3Mn1/3O2(同实施例1)，将100g的该内核材料与0.65g的氧化锡(SnO2)粉末、0.54g的四水乙酸镍(Ni(CH3COO)2·4H2O)进行混合，球磨后在管式炉中进行烧结，自然冷却至室温，得到复合正极材料；其中，球磨、烧结条件同实施例1。 Provide a core material - layered sodium cathode active material NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (same as Example 1), mix 100g of this core material with 0.65g of tin oxide (SnO 2 ) powder, 0.54 g of nickel acetate tetrahydrate (Ni(CH 3 COO) 2 ·4H 2 O) was mixed, ball milled and then sintered in a tube furnace, and naturally cooled to room temperature to obtain a composite cathode material; the ball milling and sintering conditions were the same as in the implementation example 1.
实施例2得到的复合正极材料包括NaNi1/3Fe1/3Mn1/3O2内核和形成在内核表面的NamNi1/3Sn2/3O2包覆层，将该复合正极材料记作NaNi1/3Fe1/3Mn1/3O2@NamNi1/3Sn2/3O2，其中，m在0.5-1.0之间。其中，包覆层的厚度为10nm，包覆层的质量占内核质量的1.0％。The composite cathode material obtained in Example 2 includes a NaNi 1/3 Fe 1/3 Mn 1/3 O 2 core and a Na m Ni 1/3 Sn 2/3 O 2 coating layer formed on the surface of the core. The composite cathode material is The material is recorded as NaNi 1/3 Fe 1/3 Mn 1/3 O 2 @Na m Ni 1/3 Sn 2/3 O 2 , where m is between 0.5-1.0. Among them, the thickness of the cladding layer is 10nm, and the mass of the cladding layer accounts for 1.0% of the core mass.
实施例3Example 3
一种复合正极材料的制备，包括以下步骤：A preparation method of a composite positive electrode material comprises the following steps:
提供内核材料—层状钠正极活性材料NaNi1/3Fe1/3Mn1/3O2(同实施例1)，将100g的该内核材料与1g的Na0.67Ni1/3As2/3O2进行混合，球磨后在管式炉中进行烧结，自然冷却至室温，得到复合正极材料；其中，球磨、烧结条件同实施例1。Provide a core material—layered sodium cathode active material NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (same as Example 1), mix 100g of this core material with 1g of Na 0.67 Ni 1/3 As 2/3 O 2 is mixed, ball-milled, then sintered in a tube furnace, and naturally cooled to room temperature to obtain a composite cathode material; the ball-milling and sintering conditions are the same as in Example 1.
实施例3制得的复合正极材料包括NaNi1/3Fe1/3Mn1/3O2内核和形成在内核表面的NamNi1/3As2/3O2包覆层，将该复合正极材料记作NaNi1/3Fe1/3Mn1/3O2@NamNi1/3As2/3O2，m在0.5-1.0之间。其中，包覆层的厚度为8nm。The composite cathode material prepared in Example 3 includes a NaNi 1/3 Fe 1/3 Mn 1/3 O 2 core and a Na m Ni 1/3 As 2/3 O 2 coating layer formed on the surface of the core. The composite The positive electrode material is recorded as NaNi 1/3 Fe 1/3 Mn 1/3 O 2 @Na m Ni 1/3 As 2/3 O 2 , m is between 0.5-1.0. Among them, the thickness of the cladding layer is 8nm.
实施例4Example 4
一种复合正极材料的制备，包括以下步骤：The preparation of a composite cathode material includes the following steps:
提供内核材料—层状钠正极活性材料NaAl0.05Ni0.35Fe0.2Mn0.4O2(平均粒径为3-10μm)，将100g的该内核材料与0.32g的氧化铜(CuO)粉末、1.34g的氧化碲(TeO2)混合，并在250rpm的转速下进行球磨8h，将球磨后物料置于管式炉中进行烧结，烧结条件为：从室温以5℃/min的升温速率升至烧结温度800℃，在该温度下保温烧结3h；之后自然冷却至室温，得到复合正极材料。Provide core material—layered sodium cathode active material NaAl 0.05 Ni 0.35 Fe 0.2 Mn 0.4 O 2 (average particle size 3-10 μm), mix 100g of this core material with 0.32g copper oxide (CuO) powder, 1.34g Tellurium oxide (TeO 2 ) is mixed and ball-milled at a rotation speed of 250 rpm for 8 hours. The ball-milled material is placed in a tube furnace for sintering. The sintering conditions are: from room temperature to a sintering temperature of 800 at a heating rate of 5°C/min. ℃, kept and sintered at this temperature for 3 hours; then naturally cooled to room temperature to obtain the composite cathode material.
实施例4制得的复合正极材料包括NaAl0.05Ni0.35Fe0.2Mn0.4O2内核，形成在内核表面的NamCu1/3Te2/3O2包覆层。将该复合正极材料记作NaAl0.05Ni0.35Fe0.2Mn0.4O2@NamCu1/3Te2/3O2，m在0.5-1.0之间。其中，包覆层的厚度为15nm，包覆层的质量约占内核材料质量的2.0％。The composite cathode material prepared in Example 4 includes a NaAl 0.05 Ni 0.35 Fe 0.2 Mn 0.4 O 2 core and a Na m Cu 1/3 Te 2/3 O 2 coating layer formed on the surface of the core. The composite cathode material is recorded as NaAl 0.05 Ni 0.35 Fe 0.2 Mn 0.4 O 2 @N m Cu 1/3 Te 2/3 O 2 , m is between 0.5-1.0. Among them, the thickness of the cladding layer is 15nm, and the mass of the cladding layer accounts for approximately 2.0% of the mass of the core material.
实施例5Example 5
一种复合正极材料的制备，包括以下步骤：The preparation of a composite cathode material includes the following steps:
提供内核材料—层状钠正极活性材料NaZn0.05Ni0.35Fe0.2Mn0.4O2(平均粒径为3-8μm)，将100g的该内核材料与0.16g的氧化铜(CuO)粉末、0.67g的氧化碲(TeO2)混合，球磨后在管式炉中进行烧结，自然冷却至室温，得到复合正极材料；其中，球磨、烧结条件同实施例4。Provide core material - layered sodium cathode active material NaZn 0.05 Ni 0.35 Fe 0.2 Mn 0.4 O 2 (average particle size is 3-8 μm), mix 100g of this core material with 0.16g copper oxide (CuO) powder, 0.67g Tellurium oxide (TeO 2 ) was mixed, ball-milled, and then sintered in a tube furnace, and then naturally cooled to room temperature to obtain a composite cathode material; the ball-milling and sintering conditions were the same as in Example 4.
实施例5制得的复合正极材料包括NaZn0.05Ni0.35Fe0.2Mn0.4O2内核，和形成在内核表面的NamCu1/3Te2/3O2包覆层。该复合正极材料可记作NaZn0.05Ni0.35Fe0.2Mn0.4O2@NamCu1/3Te2/3O2，m在0.5-1.0之间。其中，包覆层的厚度为14nm，包覆层的质量约占内核质量的1.0％。The composite cathode material prepared in Example 5 includes a NaZn 0.05 Ni 0.35 Fe 0.2 Mn 0.4 O 2 core and a Na m Cu 1/3 Te 2/3 O 2 coating layer formed on the surface of the core. The composite cathode material can be recorded as NaZn 0.05 Ni 0.35 Fe 0.2 Mn 0.4 O 2 @N m Cu 1/3 Te 2/3 O 2 , m is between 0.5-1.0. Among them, the thickness of the cladding layer is 14nm, and the mass of the cladding layer accounts for approximately 1.0% of the core mass.
实施例6Example 6
一种复合正极材料的制备，包括以下步骤：A preparation method of a composite positive electrode material comprises the following steps:
提供内核材料—层状钠正极活性材料NaCa0.02Ni0.33Fe0.33Mn0.33O2(单晶，平均粒径为5-7μm)，将100g的该内核材料与1g的Na0.8Mg0.1Ni1/3Bi2/3O2进行混合，并在300rpm的转速下球磨10h，将球磨后物料置于管式炉中进行烧结，烧结条件为：从室温以3℃/min的升温速率升至烧结温度700℃，在该温度下保温烧结4h；之后自然冷却至室温，得到复合正极材料。Provide core material - layered sodium cathode active material NaCa 0.02 Ni 0.33 Fe 0.33 Mn 0.33 O 2 (single crystal, average particle size is 5-7μm), mix 100g of this core material with 1g of Na 0.8 Mg 0.1 Ni 1/3 Bi 2/3 O 2 is mixed and ball-milled at 300 rpm for 10 hours. The ball-milled material is placed in a tube furnace for sintering. The sintering conditions are: from room temperature to a sintering temperature of 700 at a heating rate of 3°C/min. ℃, kept and sintered at this temperature for 4 hours; then naturally cooled to room temperature to obtain the composite cathode material.
实施例6制得的复合正极材料包括NaCa0.02Ni0.33Fe0.33Mn0.33O2内核，和形成在内核表面的NamMg0.1Ni1/3Bi2/3O2包覆层，m在0.5-1.0之间。其中，包覆层的厚度为10nm，包覆层的质量占内核质量的1.0％。The composite cathode material prepared in Example 6 includes a NaCa 0.02 Ni 0.33 Fe 0.33 Mn 0.33 O 2 core, and a Na m Mg 0.1 Ni 1/3 Bi 2/3 O 2 coating layer formed on the surface of the core, with m in 0.5- between 1.0. Among them, the thickness of the cladding layer is 10nm, and the mass of the cladding layer accounts for 1.0% of the core mass.
实施例7Example 7
一种复合正极材料的制备，包括以下步骤：The preparation of a composite cathode material includes the following steps:
提供内核材料—层状钠正极活性材料Na2Mn3O7(单晶，平均粒径为5-7μm)，将100g的该内核材料与1g的Na0.67Li0.1Ni1/3Bi2/3O2(平均粒径不超过500nm)混合，球磨后再在管式炉中进行烧结，自然冷却至室温，得到复合正极材料；其中，球磨、烧结条件同实施例6。Provide core material - layered sodium cathode active material Na 2 Mn 3 O 7 (single crystal, average particle size is 5-7 μm), mix 100g of this core material with 1g of Na 0.67 Li 0.1 Ni 1/3 Bi 2/3 O 2 (average particle size does not exceed 500 nm) is mixed, ball milled and then sintered in a tube furnace, and naturally cooled to room temperature to obtain a composite cathode material; the ball milling and sintering conditions are the same as in Example 6.
实施例7制得的复合正极材料包括Na2Mn3O7内核，形成在内核表面的NamLi0.1Ni1/3Bi2/3O2包覆层，m在0.5-1.0之间。将该复合正极材料记作Na2Mn3O7@NamLi0.1Ni1/3Bi2/3O2。其中，包覆层的厚度为9nm。 The composite cathode material prepared in Example 7 includes a Na 2 Mn 3 O 7 core and a Na m Li 0.1 Ni 1/3 Bi 2/3 O 2 coating layer formed on the surface of the core, with m between 0.5 and 1.0. The composite cathode material is denoted as Na 2 Mn 3 O 7 @N m Li 0.1 Ni 1/3 Bi 2/3 O 2 . Among them, the thickness of the cladding layer is 9nm.
实施例8Example 8
一种复合正极材料的制备，包括以下步骤：The preparation of a composite cathode material includes the following steps:
提供内核材料—层状钠正极活性材料NaNi1/3Fe1/3Mn1/3O2(同实施例1)，将100g的该内核材料与1.5g的Na0.67Ca0.05Ni1/3Ge2/3O2混合，并在200rpm的转速下球磨5h，将球磨后物料置于管式炉中进行烧结，烧结条件为：从室温以5℃/min的升温速率升至烧结温度600℃，在该温度下保温烧结3h；之后自然冷却至室温，得到复合正极材料。Provide a core material—layered sodium cathode active material NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (same as Example 1), mix 100g of this core material with 1.5g of Na 0.67 Ca 0.05 Ni 1/3 Ge 2/3 O 2 was mixed and ball milled at a speed of 200 rpm for 5 hours. The ball-milled material was placed in a tube furnace for sintering. The sintering conditions were: from room temperature to a sintering temperature of 600℃ at a heating rate of 5℃/min. Maintain and sinter at this temperature for 3 hours; then naturally cool to room temperature to obtain a composite cathode material.
其中，实施例8制得的复合正极材料包括NaNi1/3Fe1/3Mn1/3O2内核和形成在内核表面的Na0.67Ca0.05Ni1/3Ge2/3O2包覆层。其中，包覆层的厚度为9nm，包覆层的质量占内核质量的1.5％。Among them, the composite cathode material prepared in Example 8 includes a NaNi 1/3 Fe 1/3 Mn 1/3 O 2 core and a Na 0.67 Ca 0.05 Ni 1/3 Ge 2/3 O 2 coating layer formed on the surface of the core . Among them, the thickness of the cladding layer is 9nm, and the mass of the cladding layer accounts for 1.5% of the core mass.
实施例9Example 9
一种复合正极材料的制备，包括以下步骤：The preparation of a composite cathode material includes the following steps:
提供内核材料—层状钠正极活性材料NaNi1/3Fe1/3Mn1/3O2(平均粒径为3-10μm)，将100g的该内核材料与1g的Na3(VPO4)2F3(平均粒径不超过500nm)混合，经球磨后再在管式炉中进行烧结，自然冷却至室温，得到复合正极材料；其中，球磨、烧结条件同实施例1。Provide core material - layered sodium cathode active material NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (average particle size is 3-10 μm), mix 100g of this core material with 1g of Na 3 (VPO 4 ) 2 F 3 (average particle size does not exceed 500 nm) is mixed, ball milled and then sintered in a tube furnace, and naturally cooled to room temperature to obtain a composite cathode material; the ball milling and sintering conditions are the same as in Example 1.
实施例9制得的复合正极材料包括NaNi1/3Fe1/3Mn1/3O2内核，和形成在内核表面的Na3V2(PO4)2F包覆层。将该复合正极材料记作NaNi1/3Fe1/3Mn1/3O2@Na3(VPO4)2F3。其中，包覆层的厚度为5nm。The composite cathode material prepared in Example 9 includes a NaNi 1/3 Fe 1/3 Mn 1/3 O 2 core and a Na 3 V 2 (PO 4 ) 2 F coating layer formed on the surface of the core. This composite cathode material is denoted as NaNi 1/3 Fe 1/3 Mn 1/3 O 2 @Na 3 (VPO 4 ) 2 F 3 . Among them, the thickness of the cladding layer is 5nm.
实施例10Example 10
一种复合正极材料的制备，包括以下步骤：The preparation of a composite cathode material includes the following steps:
提供内核材料—层状钠正极活性材料NaNi1/3Fe1/3Mn1/3O2(平均粒径为3-10μm)，将100g的该内核材料与1g的Na2CoPO4F(平均粒径不超过500nm)混合，经球磨后再在管式炉中进行烧结，自然冷却至室温，得到复合正极材料；其中，球磨、烧结条件同实施例1。Provide core material - layered sodium cathode active material NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (average particle size is 3-10 μm), mix 100g of this core material with 1g of Na 2 CoPO 4 F (average particle size (particle size not exceeding 500 nm), mixed, ball milled and then sintered in a tube furnace, and naturally cooled to room temperature to obtain a composite cathode material; the ball milling and sintering conditions were the same as in Example 1.
实施例10制得的复合正极材料包括NaNi1/3Fe1/3Mn1/3O2内核，和形成在内核表面的Na2MnPO4F包覆层。将该复合正极材料记作NaNi1/3Fe1/3Mn1/3O2@Na2CoPO4F。其中，包覆层的厚度为6nm。The composite cathode material prepared in Example 10 includes a NaNi 1/3 Fe 1/3 Mn 1/3 O 2 core and a Na 2 MnPO 4 F coating layer formed on the surface of the core. This composite cathode material is denoted as NaNi 1/3 Fe 1/3 Mn 1/3 O 2 @Na 2 CoPO 4 F. Among them, the thickness of the cladding layer is 6nm.
为突出本申请实施例的有益效果，特提供以下对比例。In order to highlight the beneficial effects of the embodiments of the present application, the following comparative examples are provided.
对比例1Comparative example 1
直接取未经包覆的NaNi1/3Fe1/3Mn1/3O2作正极活性材料，并按实施例1相同的方法组装成扣式钠电池。Directly use uncoated NaNi 1/3 Fe 1/3 Mn 1/3 O 2 as the positive active material, and assemble it into a button sodium battery in the same manner as in Example 1.
为衡量本申请实施提供的复合正极材料的空气稳定性，测试各实施例的复合正极材料在湿度为10％的环境下存储7天，观察材料是否发生潮解吸水；此外，还将各复合正极材料按上述实施例1记载的方式配制成正极浆料，测试该正极浆料在湿度为10％的环境下发生凝胶化现象所需的时间，相关结果汇总在下表1中。In order to measure the air stability of the composite cathode materials provided by this application, the composite cathode materials of each embodiment were tested and stored in an environment with a humidity of 10% for 7 days to observe whether the materials deliquesced and absorbed water; in addition, each composite cathode material was also The positive electrode slurry was prepared in the manner described in Example 1 above, and the time required for the positive electrode slurry to undergo gelation in an environment with a humidity of 10% was tested. The relevant results are summarized in Table 1 below.
此外，表1中还汇总了本申请实施例的复合材料中，内核材料的脱钠电势、包覆层材料的脱钠电势。其中这二者的脱钠电势均是对单独的材料进行的测试，而非对复合材料进行的测试。In addition, Table 1 also summarizes the sodium removal potential of the core material and the sodium removal potential of the coating layer material in the composite material of the embodiment of the present application. The sodium removal potentials of the two are tested on separate materials, not on the composite material.
为进一步对本申请实施例的有益效果进行有力支持，对以上各实施例及对比例装配好的扣式电池特进行以下电化学性能测试：将各扣式电池在25℃下以0.5C倍率的电流进行充放电，电压范围为2.0-4.1V，记录各循环次数下的放电容量，其中，首圈放电比容量等于扣式电池的首次放电容量与扣式电池的正极活性材料的质量之比；循环50圈后的容量保持率等于循环50圈后的放电容量与首次放电容量之比。相关结果汇总在表1。In order to further strongly support the beneficial effects of the embodiments of the present application, the following electrochemical performance tests were carried out on the button batteries assembled in the above embodiments and comparative examples: each button battery was subjected to a current of 0.5C rate at 25°C. Charge and discharge, the voltage range is 2.0-4.1V, record the discharge capacity at each cycle number, where the first cycle discharge specific capacity is equal to the ratio of the first discharge capacity of the button battery to the mass of the positive active material of the button battery; cycle The capacity retention rate after 50 cycles is equal to the ratio of the discharge capacity after 50 cycles to the first discharge capacity. The relevant results are summarized in Table 1.
表1各实施例与对比例的相关结果汇总

Table 1 Summary of relevant results of each embodiment and comparative example

从表1可以看出，相较于对比例1，实施例1-10的正极浆料凝胶化时间均有所延长，这体现了包覆层对内核材料空气稳定性的改善效果；此外，采用带包覆层的复合正极材料制得的扣式电池的首圈放电克容量、循环一定圈数后的容量保持率也均有所增加，体现了活性材料包覆层能够在不牺牲电化学性能的前提下，实现空气稳定性的改善。 As can be seen from Table 1, compared with Comparative Example 1, the gelation time of the positive electrode slurry in Examples 1-10 has been prolonged, which reflects the improvement effect of the coating layer on the air stability of the core material; in addition, The first-cycle discharge gram capacity and the capacity retention rate after a certain number of cycles of button cells made of composite cathode materials with coatings also increased, demonstrating that the active material coating layer can achieve high performance without sacrificing electrochemistry. Improve air stability without sacrificing performance.

Claims (17)

  1. 一种钠电池复合正极材料，其特征在于，所述复合正极材料包括内核和包覆在所述内核上的包覆层，所述内核包括层状钠正极活性材料，所述包覆层的材料为脱钠电势高于所述内核的高电压型钠活性材料，所述高电压型钠活性材料包括通式NamEaJbGcOn所示的化合物、通式NadReQfFg所示的化合物及Na3V(PO3)3N中的至少一种；A composite cathode material for sodium batteries, characterized in that the composite cathode material includes an inner core and a coating layer covering the inner core, the inner core includes a layered sodium positive electrode active material, and the material of the coating layer It is a high-voltage sodium active material with a sodium removal potential higher than that of the core. The high-voltage sodium active material includes a compound represented by the general formula Na m E a J b G c On , the general formula Na d Re Q At least one of the compound represented by f F g and Na 3 V(PO 3 ) 3 N;
    其中，0<m≤3，0<a≤3，0<n≤3，0<b≤3，0≤c≤3，E为可变价过渡金属元素，J包括Ga、Ge、As、Se、In、Sn、Sb、Te、Tl、Bi中的一种或多种，G包括Li、Mg、Zn、Ru、Ir中的一种或多种；Among them, 0<m≤3, 0<a≤3, 0<n≤3, 0<b≤3, 0≤c≤3, E is a variable valence transition metal element, and J includes Ga, Ge, As, Se, One or more of In, Sn, Sb, Te, Tl, Bi, G includes one or more of Li, Mg, Zn, Ru, Ir;
    0<d≤4，0<e≤4，0<f≤4，0<g≤3，R表示金属元素，Q表示聚阴离子基团，F表示氟元素。0<d≤4, 0<e≤4, 0<f≤4, 0<g≤3, R represents metal element, Q represents polyanionic group, and F represents fluorine element.
  2. 如权利要求1所述的钠电池复合正极材料，其特征在于，所述高电压型钠活性材料比所述内核的脱钠电势至少高0.2V。The sodium battery composite cathode material according to claim 1, wherein the high-voltage sodium active material has a desodium potential higher than that of the core by at least 0.2V.
  3. 如权利要求1或2所述的钠电池复合正极材料，其特征在于，所述高电压型钠活性材料的脱钠电势在3.3V以上。The sodium battery composite positive electrode material according to claim 1 or 2, characterized in that the sodium removal potential of the high-voltage sodium active material is above 3.3V.
  4. 如权利要求1-3任一项所述的钠电池复合正极材料，其特征在于，所述E包括V、Cr、Fe、Co、Ni、Mn、Cu、Ti中的一种或多种。The sodium battery composite cathode material according to any one of claims 1 to 3, wherein the E includes one or more of V, Cr, Fe, Co, Ni, Mn, Cu, and Ti.
  5. 如权利要求1-3任一项所述的钠电池复合正极材料，其特征在于，所述R选自V、Fe、Cr、Mn、Co、Ni、Cu、Ti、Zr、Al中的一种或多种；所述Q选自磷的含氧酸根、硫的含氧酸根、硅的含氧酸根、硼的含氧酸根中的一种或多种。The sodium battery composite cathode material according to any one of claims 1 to 3, characterized in that the R is selected from one of V, Fe, Cr, Mn, Co, Ni, Cu, Ti, Zr, and Al or more; the Q is selected from one or more types of oxyacid radicals of phosphorus, oxyacid radicals of sulfur, oxyacid radicals of silicon, and oxyacid radicals of boron.
  6. 如权利要求5所述的钠电池复合正极材料，其特征在于，所述通式NadReQfFg所示的化合物包括Na2CoPO4F、Na2NiPO4F、Na2MnPO4F、Na2CrPO4F、NaVPO4F、Na3V2(PO4)2F3、Na3VCo(PO4)2F3、Na3VNi(PO4)2F3、Na3VMn(PO4)2F3、Na3VCr(PO4)2F3或Na3GaV(PO4)2F3。The sodium battery composite cathode material according to claim 5, wherein the compound represented by the general formula Na d Re Q f F g includes Na 2 CoPO 4 F, Na 2 NiPO 4 F, Na 2 MnPO 4 F, Na 2 CrPO 4 F, NaVPO 4 F, Na 3 V 2 (PO 4 ) 2 F 3 , Na 3 VCo(PO 4 ) 2 F 3 , Na 3 VNi(PO 4 ) 2 F 3 , Na 3 VMn( PO 4 ) 2 F 3 , Na 3 VCr(PO 4 ) 2 F 3 or Na 3 GaV(PO 4 ) 2 F 3 .
  7. 如权利要求1-6任一项所述的钠电池复合正极材料，其特征在于，所述层状钠正极活性材料表示为NaxAyMzDuOv，其中，0<x≤12，0<y≤12，0≤z≤12，0≤u≤12，0<v≤12，A为可变价过渡金属元素，M包括Li、Al、Mg、Ca、K、Zn、Sn中的一种或多种，D包括C、P、Si、B、W中的一种或多种。The sodium battery composite cathode material according to any one of claims 1 to 6, wherein the layered sodium cathode active material is expressed as Na x A y M z D u O v , where 0<x≤12 , 0<y≤12, 0≤z≤12, 0≤u≤12, 0<v≤12, A is a variable valence transition metal element, M includes Li, Al, Mg, Ca, K, Zn, Sn One or more, D includes one or more of C, P, Si, B, and W.
  8. 如权利要求7所述的钠电池复合正极材料，其特征在于，所述A包括V、Cr、Fe、Co、Ni、Mn、Cu、Ti中的一种或多种。The sodium battery composite cathode material according to claim 7, wherein A includes one or more of V, Cr, Fe, Co, Ni, Mn, Cu, and Ti.
  9. 如权利要求1-8任一项所述的钠电池复合正极材料，其特征在于，所述包覆层完全包覆所述内核的表面。The sodium battery composite cathode material according to any one of claims 1 to 8, wherein the coating layer completely covers the surface of the core.
  10. 如权利要求1-9任一项所述的钠电池复合正极材料，其特征在于，所述包覆层的厚度为0.5nm-200nm。The sodium battery composite positive electrode material according to any one of claims 1 to 9, characterized in that the thickness of the coating layer is 0.5 nm to 200 nm.
  11. 如权利要求1-10任一项所述的钠电池复合正极材料，其特征在于，所述包覆层的质量是所述内核质量的0.1wt％-20wt％。The sodium battery composite cathode material according to any one of claims 1 to 10, wherein the mass of the coating layer is 0.1wt%-20wt% of the mass of the core.
  12. 如权利要求1-11任一项所述的钠电池复合正极材料，其特征在于，所述内核的体相中掺杂有源自所述包覆层的元素。The sodium battery composite cathode material according to any one of claims 1 to 11, wherein the bulk phase of the core is doped with elements derived from the coating layer.
  13. 如权利要求1-12任一项所述的钠电池复合正极材料，其特征在于，所述内核与所述包覆层之间还具有扩散层，所述扩散层包括所述内核的材料和所述包覆层的材料。The sodium battery composite positive electrode material according to any one of claims 1 to 12, characterized in that there is also a diffusion layer between the core and the coating layer, and the diffusion layer includes the material of the core and the material of the coating layer.
  14. 一种正极极片，其特征在于，所述正极极片包括如权利要求1-13任一项所述的钠电池复合正极材料。A positive electrode sheet, characterized in that the positive electrode sheet includes the sodium battery composite positive electrode material according to any one of claims 1-13.
  15. 一种钠二次电池，其特征在于，所述钠二次电池包括如权利要求14所述的正极极片。A sodium secondary battery, characterized in that the sodium secondary battery includes the positive electrode plate according to claim 14.
  16. 一种电子设备，其特征在于，所述电子设备包括如权利要求15所述的钠二次电池。An electronic device, characterized in that the electronic device includes the sodium secondary battery according to claim 15.
  17. 一种储能***，其特征在于，所述储能***包括如权利要求15所述的钠二次电池。 An energy storage system, characterized in that the energy storage system includes the sodium secondary battery according to claim 15.
PCT/CN2023/120159 2022-09-23 2023-09-20 Composite positive electrode material of sodium battery and use thereof WO2024061289A1 (en)

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CN110277540A (en) * 2018-03-14 2019-09-24 中国科学院物理研究所 A kind of core-shell structure sodium-ion battery positive material and its preparation method and application
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CN114824269A (en) * 2022-03-30 2022-07-29 北京当升材料科技股份有限公司 Composite positive electrode material, preparation method and application thereof, sodium ion battery pack and equipment
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106058212A (en) * 2016-08-03 2016-10-26 苏州大学 Composite cathode material of sodium-ion battery and preparation method of composite cathode material
CN110277540A (en) * 2018-03-14 2019-09-24 中国科学院物理研究所 A kind of core-shell structure sodium-ion battery positive material and its preparation method and application
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