WO2025112604A1 - 正极材料组合物及其制备方法、正极、钠电池和用电装置 - Google Patents

正极材料组合物及其制备方法、正极、钠电池和用电装置 Download PDF

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Publication number
WO2025112604A1
WO2025112604A1 PCT/CN2024/108984 CN2024108984W WO2025112604A1 WO 2025112604 A1 WO2025112604 A1 WO 2025112604A1 CN 2024108984 W CN2024108984 W CN 2024108984W WO 2025112604 A1 WO2025112604 A1 WO 2025112604A1
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Prior art keywords
positive electrode
electrode active
sodium
manganese
nickel
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English (en)
French (fr)
Inventor
吴凯
唐正
欧阳少聪
叶永煌
李全国
金海族
陈佳华
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Contemporary Amperex Technology Co Ltd
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Contemporary Amperex Technology Co Ltd
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Priority to KR1020267020270A priority Critical patent/KR20260116746A/ko
Priority to AU2024391729A priority patent/AU2024391729A1/en
Publication of WO2025112604A1 publication Critical patent/WO2025112604A1/zh
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • 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
    • H01M4/50—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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application belongs to the technical field of sodium batteries, and specifically relates to a positive electrode material composition and a preparation method thereof, a positive electrode, a sodium battery and an electrical device.
  • Sodium-ion batteries have the advantages of abundant raw material reserves, low price, relatively stable chemical properties and good safety, and are expected to replace lithium-ion batteries in the market. With the continuous development of new energy vehicles and the increasing proportion of clean energy, higher requirements are placed on the energy conversion efficiency, energy density and cycle stability of ion batteries.
  • the impedance of the battery cell and the stability of the impedance are one of the important factors affecting the energy conversion efficiency of the battery cell.
  • the impedance stability of current battery cells such as sodium batteries needs to be further improved to better meet the current market needs for battery applications.
  • the present application provides a positive electrode material composition and a preparation method thereof, a positive electrode containing the positive electrode material composition, and a sodium battery containing the positive electrode, so as to solve the technical problem of unsatisfactory impedance stability of existing battery cells.
  • the embodiment of the present application provides a positive electrode material composition.
  • the positive electrode material composition of the embodiment of the present application includes at least two nickel-iron-manganese-based sodium positive electrode active materials, each of which is physically mixed, and the mixture of the nickel-iron-manganese-based sodium positive electrode active materials also contains Cu element and Q element, and in the unit molar amount of the positive electrode material composition, the total molar content of Na is 0.78 to 1 mol;
  • the total molar content of Ni is 0.12-0.38 mol
  • the total molar content of Mn is 0.18-0.48 mol
  • the total molar content of Fe is 0.18-0.35 mol
  • the total molar content of Cu is 0.01-0.14 mol
  • the Q includes at least one element of Zn, Mg, and Ti.
  • the positive electrode material composition of the embodiment of the present application uses two or more nickel-iron-manganese-based sodium positive electrode active materials to form a physical mixture, and the content of metal elements such as Na, Ni, Mn, Fe, Cu, and Q contained in the mixture is controlled within the above range, so that the direct current internal resistance (DCR) of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charging and discharging process is relatively stable, and the DCR growth rate of the battery cell during the charging and discharging process can be significantly reduced. On this basis, the energy density and cycle performance of the battery cell can also be improved.
  • DCR direct current internal resistance
  • the molar content of at least one element among Na, Ni, Mn, Fe, Cu and Y is:
  • the total molar content of Na is 0.8 to 1 mol
  • the total molar content of Ni is 0.15-0.35 mol
  • the total molar content of Mn is 0.20-0.45 mol
  • the total molar content of Fe is 0.20-0.33 mol
  • the total molar content of Q is 0.01 to 0.06 moL
  • the total molar content of Cu is 0.02-0.09 mol.
  • the disordered arrangement of the metal elements in the transition metal layer contained in each nickel-iron-manganese-based sodium positive electrode active material can be further adjusted, and the distance between the transition metal layer and the sodium layer can be adjusted to further improve the positive electrode of the present application.
  • the DC internal resistance (DCR) stability performance of the battery cell of the material composition during the charge and discharge process, especially the Cu element and the metal element shown in Q in the above range can enhance the DCR stability of the battery cell, further improve the DCR stability of the battery cell.
  • the cycle performance and gram capacity of each nickel-iron-manganese-based sodium positive electrode active material are further improved.
  • At least one of the nickel-iron-manganese-based sodium positive electrode active materials also contains active or/and inert doped metal elements.
  • the total molar content of the doped metal elements is greater than 0, less than or equal to 0.13 moL, and can be selected as greater than 0, less than or equal to 0.1 moL.
  • the doped metal elements in this content range can participate in the disordered arrangement between the metal elements in the transition metal layer contained in the nickel-iron-manganese-based sodium positive electrode active material and can adjust the distance between the transition metal layer and the sodium layer.
  • each nickel-iron-manganese-based sodium positive electrode active material can also improve the relevant electrochemical properties of each nickel-iron-manganese-based sodium positive electrode active material, and further improve the DC internal resistance (DCR) stability performance of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charging and discharging process, so as to alleviate the growth of the DCR of the battery cell during the charging and discharging process.
  • DCR DC internal resistance
  • the doping metal element includes at least one of V, Ca, Cr, Al, Sc, Sn, Sb, Zr, Nb, Ru, and Ir.
  • These types of doping metal elements dope the transition metal layer contained in the nickel-iron-manganese-based sodium positive electrode active material containing the doping metal elements, adjust the disordered arrangement of the metal elements in the transition metal layer, and can adjust the distance between the transition metal layer and the sodium layer, which can further improve the DC internal resistance (DCR) stability performance of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charging and discharging process, so as to alleviate the growth of the DCR of the battery cell during the charging and discharging process and improve the structural stability and/or gram capacity of the nickel-iron-manganese-based sodium positive electrode active material.
  • DCR DC internal resistance
  • the molar content of the Na element and the total molar content of other metal elements have a ratio of (0.81 to 0.89): 1, and may be (0.82 to 0.89): 1.
  • Controlling the total molar content of the Na element and the total molar content of other metal elements within this range can further adjust the content of sodium ions, increase the sodium ion content that can be intercalated and deintercalated in the nickel-iron-manganese-based sodium positive electrode active material, thereby increasing the reversible capacity of the positive electrode material composition; and can improve the structural stability of the nickel-iron-manganese-based sodium positive electrode active material to improve its cycle performance.
  • the Cu element and the Q element are distributed in different nickel-iron-manganese-based sodium positive electrode active materials.
  • the nickel-iron-manganese-based sodium positive electrode active material containing the Cu element and the nickel-iron-manganese-based sodium positive electrode active material containing the Q element are compounded to form a mixture, the gram capacity and cycle performance of the positive electrode material composition of the embodiment of the present application can be balanced, and the DC internal resistance (DCR) stability performance of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charging and discharging process can be further improved to alleviate the growth of the DCR of the battery cell during the charging and discharging process.
  • DCR DC internal resistance
  • the nickel-iron-manganese-based sodium positive electrode active material containing the Q element comprises at least one of the following (1) to (4):
  • Dv50 particle size is 3-8 ⁇ m, and can be 4-6.5 ⁇ m;
  • Dv90 particle size is 8-16 ⁇ m, and can be 10-14 ⁇ m;
  • the compaction density under a pressure of 3 tons is higher than 3.1 g/cm 3 , and may be 3.1 to 3.4 g/cm 3 ;
  • the specific surface area is 0.4 to 1.0 m 2 /g, and can be optionally 0.6 to 0.9 m 2 /g.
  • the nickel-iron-manganese-based sodium positive electrode active material containing the Cu element comprises at least one of the following (1) to (4):
  • Dv50 particle size is 5-11 ⁇ m, and can be 6.5-10 ⁇ m;
  • Dv90 particle size is 13-19 ⁇ m, and can be selected as 14.5-18 ⁇ m;
  • the compaction density under a pressure of 3 tons is 3.0 to 3.3 g/cm 3 , and can be optionally 3.0 to 3.25 g/cm 3 ;
  • the specific surface area is 0.4 to 0.7 m 2 /g, and can be optionally 0.5 to 0.6 m 2 /g.
  • the nickel-iron-manganese-based sodium positive electrode active material containing Q element and the nickel-iron-manganese-based sodium positive electrode active material containing Cu element have the above-mentioned range characteristics, which can improve the stability of the contact interface between the positive electrode material composition of the embodiment of the present application and the electrolyte and improve the DC internal resistance (DCR) stability of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charge and discharge process.
  • DCR DC internal resistance
  • the gram capacity and cycle performance of the positive electrode material composition of the embodiment of the present application can also be improved.
  • each of the nickel-iron-manganese-based sodium positive electrode active materials independently comprises at least one of the following (1) to (2):
  • the crystal structure includes an O3 phase layered metal oxide, and the O3 phase layered metal oxide accounts for more than 95% of the total weight of the layered oxide; and/or
  • the single crystal O3 phase nickel-iron-manganese-based sodium positive electrode active material has relatively high structural stability and improves the cycle performance of the battery cell.
  • the positive electrode material composition has a discharge capacity in grams at 1.5 to 4.2 V and 0.1 C of 115 to 128 mAh/g, and may be 120 to 128 mAh/g.
  • the present invention provides a method for preparing a positive electrode material composition.
  • the method for preparing a positive electrode material composition in the present invention comprises the following steps:
  • At least two nickel-iron-manganese-based sodium positive electrode active materials are physically mixed according to the molar content ratio of Na, Ni, Mn, Fe, Q and Cu contained in the above-mentioned positive electrode material composition per unit mole to form a positive electrode material composition.
  • the preparation method of the positive electrode material composition of the embodiment of the present application is to mix at least two nickel-iron-manganese-based sodium positive electrode active materials in a proportion within the content range of Na, Ni, Mn, Fe, Cu, and Q, so that the battery cell containing the positive electrode material composition of the embodiment of the present application has a small increase rate of direct current internal resistance (DCR) during the charge and discharge process, and also makes the positive electrode material composition of the embodiment of the present application have high gram capacity and cycle performance.
  • DCR direct current internal resistance
  • the present invention provides a positive electrode, which includes a positive electrode active material layer, wherein the positive electrode active material layer includes a positive electrode material composition of the present invention or a positive electrode material composition prepared by a method for preparing a positive electrode material composition of the present invention.
  • the battery cell containing the positive electrode of the embodiment of the present application has a small increase rate of direct current internal resistance (DCR) during the charge and discharge process. At the same time, the battery cell has a high energy density and good cycle performance.
  • DCR direct current internal resistance
  • the content of the positive electrode active material layer on a single surface of the current collector is 260-350 mg/1540.25 mm 2 , and may be 280-320 mg/1540.25 mm 2 .
  • the compaction density of the positive electrode is 2.6 to 3.4 g/cm 3 , and can be 2.8 to 3.2 g/cm 3 .
  • the porosity of the positive electrode active material layer is 40% to 70%, and can be optionally 50% to 65%.
  • the positive electrode is a pole piece, and the ratio of the thickness from one surface of the pole piece to the other opposite surface to the thickness of the current collector is 7 to 15:1, and can be optionally 8 to 14:1.
  • the positive electrode is a pole piece
  • the membrane resistance of the pole piece is 0.5 to 5 m ⁇ , and can be optionally 0.5 to 3 m ⁇ .
  • the contact interface between the electrode and the electrolyte is stable, so that the direct current internal resistance (DCR) of the battery cell containing the positive electrode of the embodiment of the present application is relatively stable during the charge and discharge process, and the energy density of the battery cell is high and the cycle performance is good.
  • DCR direct current internal resistance
  • the conductive agent contained in the positive electrode active material layer includes a linear conductive agent.
  • the linear conductive agent includes at least one of the following (1) to (5):
  • the mass content of the positive electrode active material layer is 0.1% to 2.5%, and can be 0.3% to 0.7%;
  • the aspect ratio is 40 to 3000:1, and can be selected as 50 to 2500:1;
  • the length is 0.5 to 5 ⁇ m, and can be optionally 0.5 to 2 ⁇ m;
  • the diameter is 2 to 10 nm, and can be 3 to 7 nm;
  • a linear conductive agent is added to the positive electrode active material layer, and the content of the linear conductive agent is controlled within the range, and the type, aspect ratio, length and diameter of the linear conductive agent are selected within the above range, so that the linear conductive agent can form a rich conductive network structure in the positive electrode active material layer, and the linear conductive agent can also be wound on the surface of the flat single crystal particles.
  • the granular conductive agent can be effectively dispersed in the gaps of the positive electrode material composition. In this way, the linear conductive agent effectively improves the conductivity of the positive electrode active material layer, can significantly reduce the internal resistance of the positive electrode, and is also conducive to improving the DCR stability of the battery electrical properties during the charge and discharge process.
  • the present invention provides a sodium battery.
  • the sodium battery of the present invention comprises the positive electrode of the present invention.
  • the electrode assembly of the sodium battery of the present invention has a contact interface stability with the electrolyte.
  • the DC internal resistance (DCR) during the charge and discharge process is stable.
  • the battery cell also has electrochemical properties such as high energy density and good cycle performance.
  • the sodium battery is a sodium battery cell, and the sodium battery cell includes at least one of the following (1) to (3):
  • the operating voltage is 1.5 to 4.0 V; and/or
  • the DC resistance growth rate of the sodium battery cell is less than 180%.
  • an embodiment of the present application provides an electrical device, and the embodiment of the present application includes a sodium battery according to an embodiment of the present application.
  • the electrical device in the embodiment of the present application has a long standby or battery life and a long service life.
  • FIG1 is a schematic diagram of a structure of a positive electrode in some embodiments of the present application.
  • FIG2 is another schematic diagram of the structure of the positive electrode of some embodiments of the present application.
  • FIG3 is a schematic structural diagram of an embodiment of a sodium battery cell of the present application.
  • FIG4 is an exploded schematic diagram of the sodium battery cell shown in FIG3 ;
  • FIG5 is a schematic structural diagram of an implementation scheme of a battery module according to an embodiment of the present application.
  • FIG6 is a schematic structural diagram of an implementation scheme of a battery pack according to an embodiment of the present application.
  • FIG7 is a schematic diagram of the exploded structure of the battery pack shown in FIG6 ;
  • FIG. 8 is a schematic diagram of an embodiment of an electrical device including a battery according to an embodiment of the present application as a power source.
  • the term "and/or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships.
  • a and/or B can represent: A exists alone, A and B exist at the same time, and B exists alone.
  • the character "/" in this article generally indicates that the associated objects before and after are in an "or" relationship.
  • multiple refers to more than two (including two).
  • multiple groups refers to more than two groups (including two groups), and “multiple pieces” refers to more than two pieces (including two pieces).
  • Sodium-ion batteries are ideal candidates for energy storage systems due to their abundant raw material reserves and low price. They also have huge application space in the new energy vehicle market. With the rapid development of energy storage systems and new energy vehicles, the market has higher and higher requirements for the energy conversion efficiency, energy density and cycle stability of batteries, including sodium-ion batteries.
  • the impedance and impedance stability of the battery cell are one of the important factors affecting the energy conversion efficiency of the battery cell.
  • reducing the impedance of the battery cell or improving the stability of the impedance generally includes optimizing the pole piece design, improving the wettability of the electrolyte, and adopting advanced process technology.
  • these methods are not particularly ideal for improving the impedance and impedance stability of the battery cell.
  • they will also lead to a decrease in the chemical properties of the battery cell such as energy density or cycle performance or an increase in cost.
  • the positive electrode material of sodium-ion batteries can provide active sodium ions and is an important component of sodium-ion batteries.
  • sodium-electrolyte layered oxides have attracted much attention due to their higher gram capacity and structure similar to that of lithium-ion battery positive electrode materials.
  • sodium layered oxide cathode materials Based on the structure of sodium layered oxide cathode materials, it is currently believed that sodium layered oxide cathode materials have an important relationship with the energy density and cycle performance of sodium battery cells. Therefore, the industry is currently also adjusting the crystal stability and doping of sodium layered oxide cathode materials to improve the electrochemical properties such as gram capacity and structural stability of sodium layered oxide cathode materials, so as to achieve the purpose of improving the energy density and cycle performance of sodium battery cells.
  • a composition of sodium-based layered oxide positive electrode materials is proposed.
  • the composition of sodium-based layered oxide positive electrode materials is formed by physically mixing and compounding at least two types of sodium-based layered oxide positive electrode materials, and the type and content of transition metal elements in the composition are regulated.
  • DCR DC internal resistance
  • the electrochemical properties of the battery cell such as energy density and cycle performance, can also be improved.
  • the embodiments of the present application provide a positive electrode material composition.
  • the positive electrode material composition of the embodiments of the present application includes at least two nickel-iron-manganese-based sodium positive electrode active materials, each of which is physically mixed, and the mixture formed by the nickel-iron-manganese-based sodium positive electrode active materials also contains Cu and Q elements.
  • the contents of Na, Ni, Mn, Fe, Cu, and Q are as follows:
  • the total molar content of Na is 0.78 to 1 moL
  • the total molar content of Ni is 0.12-0.38 mol
  • the total molar content of Mn is 0.18-0.48 mol
  • the total molar content of Fe is 0.18-0.35 mol
  • the total molar content of Q is 0.01 to 0.12 moL
  • the total molar content of Cu is 0.01-0.14 mol
  • Q includes at least one element of Zn, Mg and Ti.
  • the nickel-iron-manganese-based sodium positive electrode active material refers to a sodium layered oxide positive electrode material containing nickel, iron and manganese elements.
  • the sodium layered oxide positive electrode material refers to a positive electrode material composed of transition metal layers (TMO 6 ) and sodium layers (NaO 6 ) arranged alternately and containing Ni, Mn, Fe, etc.
  • Physical mixing refers to physically mixing at least two of the above nickel-iron-manganese-based sodium positive electrode active materials, doping the amorphous phase, such as not undergoing treatment such as sintering after mixing.
  • the positive electrode material composition of the embodiment of the present application is physically mixed with two or more nickel-iron-manganese-based sodium positive electrode active materials, and the content of metal elements such as Na, Ni, Mn, Fe, Cu, and Q contained in the mixture is controlled within the above range, so that the direct current internal resistance (DCR) of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charging and discharging process is relatively stable, and the DCR growth rate of the battery cell during the charging and discharging process can be significantly reduced.
  • the Cu element and the metal element shown in Q in the above range of content can play a synergistic role in the stability of the DCR of the battery cell in the electrode material composition, and can significantly improve the DCR stability of the battery cell.
  • At least one nickel-iron-manganese-based sodium positive electrode active material contains the Cu element and the Q element in the above-mentioned molar content range
  • the Cu element and the Q element participate in the disordered arrangement between the metal elements in the transition metal layer contained in the nickel-iron-manganese-based sodium positive electrode active material and can adjust the distance between the transition metal layer and the sodium layer
  • the structural stability and/or gram capacity of the nickel-iron-manganese-based sodium positive electrode active material in the process of sodium insertion and extraction is improved, and the gram capacity and cycle performance of the positive electrode material composition of the embodiment of the present application are improved, thereby correspondingly improving the energy density and cycle performance of the battery cell.
  • the total molar content of the Na element in the positive electrode material composition per unit molar amount, may be 0.78 to 1 moL, optionally 0.8 to 1 moL, and further 0.89 to 0.91 moL.
  • the total molar content of the Na element may be 0.78 moL, 0.8 moL, 0.82 moL, 0.85 moL, 0.88 moL, 0.89 moL, 0.9 moL, 0.91 moL, 0.92 moL, 0.95 moL, 0.98 moL, 1.0 moL, and other typical but non-limiting stoichiometric contents or the range between any two stoichiometric content values.
  • the Na element in this content range increases the reversible capacity of the positive electrode material composition.
  • the total molar content of the Ni element in the unit molar amount of the positive electrode material composition, can be 0.12-0.38 moL, optionally 0.15-0.35 moL, and further can be 0.2-0.3 moL.
  • the total molar content of the Ni element can be 0.12 moL, 0.15 moL, 0.18 moL, 0.20 moL, 0.22 moL, 0.25 moL, 0.28 moL, 0.30 moL, 0.32 moL, 0.35 moL, 0.38 moL and other typical but non-limiting stoichiometric contents or the range between any two stoichiometric content values.
  • the total molar content of the Fe element in the unit molar amount of the positive electrode material composition, can be 0.18-0.35 moL, optionally 0.20-0.33 moL, and further can be 0.24-0.28 moL. In the exemplary embodiment, the total molar content of the Fe element can be 0.18 moL, 0.20 moL, 0.22 moL, 0.24 moL, 0.25 moL, 0.28 moL, 0.30 moL, 0.32 moL, 0.33 moL and other typical but non-limiting stoichiometric contents or the range between any two stoichiometric content values.
  • At least one of the Ni element and Fe element in the above-mentioned content range can participate in the disordered arrangement of metal elements in the transition metal layer contained in each nickel-iron-manganese-based sodium positive electrode active material together with the Cu element or Q element of the above-mentioned content, Mn element and other elements contained in each nickel-iron-manganese-based sodium positive electrode active material, and can adjust the spacing between the transition metal layer and the sodium layer, etc., thereby improving the relevant electrochemical properties of each nickel-iron-manganese-based sodium positive electrode active material, thereby further improving the DC internal resistance (DCR) stability performance of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charging and discharging process, and further alleviating the growth of the DCR of the battery cell during the charging and discharging process.
  • DCR DC internal resistance
  • the gram capacity of the nickel-iron-manganese-based sodium positive electrode active material can also be increased to increase the gram capacity of the positive electrode material composition of the embodiment of the present application.
  • the structural stability of the nickel-iron-manganese-based sodium positive electrode active material in the process of sodium deintercalation can be further improved, and the cycle performance of the positive electrode material composition of the embodiment of the present application can be improved.
  • the total molar content of Mn element in the positive electrode material composition per unit mole can be 0.18-0.48moL, optionally 0.20-0.45moL, further 0.39-0.41moL.
  • the total molar content of the Mn element can be 0.18moL, 0.20moL, 0.22moL, 0.25moL, 0.28moL, 0.30moL, 0.32moL, 0.35moL, 0.38moL, 0.39moL, 0.40moL, 0.41moL, 0.42moL, 0.45moL, 0.48moL and other typical but non-limiting stoichiometric contents or the range between any two stoichiometric content values.
  • the Mn element in this content range can participate in the relevant electrochemical properties of each nickel-iron-manganese-based sodium positive electrode active material together with the elements such as Cu element or Q element of the above content, Ni element, Fe element, etc. contained in each nickel-iron-manganese-based sodium positive electrode active material, further improving the DC internal resistance (DCR) stability performance of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charging and discharging process, and further alleviating the growth of DCR of the battery cell during the charging and discharging process.
  • DCR DC internal resistance
  • the total molar content of the Q element in the unit molar amount of the positive electrode material composition, can be 0.01-0.12 moL, optionally 0.01-0.1 moL, and further can be 0.01-0.06 moL.
  • the total molar content of the Q element can be 0.01 moL, 0.02 moL, 0.03 moL, 0.04 moL, 0.05 moL, 0.06 moL, 0.07 moL, 0.08 moL, 0.09 moL, 0.10 moL, 0.11 moL, 0.12 moL and other typical but non-limiting stoichiometric contents or the range between any two stoichiometric content values.
  • the Q element can also participate in the disordered arrangement between the metal elements in the transition metal layer of the nickel-iron-manganese-based sodium positive electrode active material containing the Q element, and adjust the distance between the transition metal layer and the sodium layer, thereby improving the relevant electrochemical properties of each nickel-iron-manganese-based sodium positive electrode active material, and further improving the DC internal resistance (DCR) stability performance of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charging and discharging process, so as to alleviate the growth of the DCR of the battery cell during the charging and discharging process.
  • the metal element shown in Q in the above content range can also further play a synergistic role in the stability of the DCR of the battery cell in the composition with the Cu element in the above range content, and further improve the DCR stability of the battery cell.
  • it can also further improve the full utilization of the gram capacity of the nickel-iron-manganese-based sodium positive electrode active material containing the Q element in the process of sodium deintercalation, thereby improving the gram capacity of the positive electrode material composition of the embodiment of the present application; it can also reduce the migration of the Fe element in the nickel-iron-manganese-based sodium positive electrode active material containing the Q element, improve the structural stability of each nickel-iron-manganese-based sodium positive electrode active material in the process of sodium deintercalation, and improve the cycle performance of the positive electrode material composition of the embodiment of the present application.
  • the total molar content of the Cu element in the unit molar amount of the positive electrode material composition, can be 0.01-0.14 moL, optionally 0.01-0.12 moL, and further can be 0.02-0.09 moL, 0.02-0.07 moL.
  • the total molar content of the Cu element can be 0.01 moL, 0.02 moL, 0.03 moL, 0.04 moL, 0.05 moL, 0.06 moL, 0.07 moL, 0.08 moL, 0.09 moL, 0.10 moL, 0.11 moL, 0.12 moL, 0.13 moL, 0.14 moL, etc., typical but non-limiting stoichiometric contents or the range between any two stoichiometric content values.
  • the Cu element can also participate in the disordered arrangement between the metal elements in the transition metal layer of the nickel-iron-manganese-based sodium positive electrode active material containing the Cu element, adjust the distance between the transition metal layer and the sodium layer, and also improve the relevant electrochemical properties of each nickel-iron-manganese-based sodium positive electrode active material, thereby further improving the DC internal resistance (DCR) stability performance of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charge and discharge process, so as to alleviate the growth of the DCR of the battery cell during the charge and discharge process.
  • DCR DC internal resistance
  • the Cu element in the above content range can also further play a synergistic role in the stability of the DCR of the battery cell in the composition with the metal element shown in the Q content range above, further improving the DCR stability of the battery cell.
  • the structural stability of the nickel-iron-manganese-based sodium positive electrode active material containing the Cu element in the process of sodium deintercalation can also be further improved.
  • At least one nickel-iron-manganese-based sodium positive electrode active material contained in the positive electrode material composition of the embodiment of the present application further contains active and/or inert doped metal elements.
  • the total molar content of the doped metal elements is greater than 0 and less than or equal to 0.13moL; it can be optionally greater than 0 and less than or equal to 0.1moL; in the exemplary embodiment, the total molar content of the doped metal elements can be 0.01moL, 0.02moL, 0.03moL, 0.04moL, 0.05moL, 0.06moL, 0.07moL, 0.08moL, 0.09moL, 0.10moL, 0.11moL, 0.12moL, 0.13moL, etc.
  • the doping metal element in this content range can participate in the disordered arrangement of metal elements in the transition metal layer contained in the nickel-iron-manganese-based sodium positive electrode active material containing the doping metal element and can adjust the distance between the transition metal layer and the sodium layer.
  • the relevant electrochemical properties of each nickel-iron-manganese-based sodium positive electrode active material can also be improved, thereby further improving the DC internal resistance (DCR) stability performance of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charge and discharge process, so as to alleviate the growth of the DCR of the battery cell during the charge and discharge process.
  • DCR DC internal resistance
  • the structural stability and/or gram capacity of the nickel-iron-manganese-based sodium positive electrode active material containing the doped metal element can be further improved.
  • the content of the Ni element can be reduced, thereby reducing the economic cost of the nickel-iron-manganese-based sodium positive electrode active material containing the doped metal element.
  • the above-mentioned doping metal elements may include at least one of V, Cr, Ca, Al, Sc, Sn, Sb, Zr, Nb, Ru, and Ir.
  • the active doping metal elements may include at least one metal element of V, Cr, Sc, Sn, Sb, Nb, Ca, etc.
  • the inert doping metal elements may be at least one metal element of Al, Zr, Ir, Ru, etc.
  • doping metal elements dope the transition metal layer contained in the nickel-iron-manganese-based sodium positive electrode active material containing doping metal elements, adjust the disordered arrangement of the metal elements in the transition metal layer, and can adjust the distance between the transition metal layer and the sodium layer, which can further improve the DC internal resistance (DCR) stability performance of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charging and discharging process, so as to alleviate the growth of the DCR of the battery cell during the charging and discharging process.
  • DCR DC internal resistance
  • inert doped metal elements can also reduce the sensitivity to iron sites, and can assist the Mn element to further improve the structural stability of the nickel-iron-manganese-based sodium positive electrode active material containing doped metal elements during the sodium deintercalation process, and further improve the cycle performance of the nickel-iron-manganese-based sodium positive electrode active material containing doped metal elements.
  • active doped metal elements can also further increase the gram capacity of the nickel-iron-manganese-based sodium positive electrode active material containing doped metal elements with the Fe element, thereby correspondingly increasing the energy density of the battery cell.
  • the total molar content of Na, Ni, Mn, Fe, Cu and Q, and doped metal elements in the positive electrode material composition per molar amount may be as follows:
  • the total molar content of Na is 0.8 to 1 moL
  • the total molar content of Ni is 0.15-0.35 mol
  • the total molar content of Mn is 0.20-0.45 mol
  • the total molar content of Fe is 0.20-0.33 mol
  • the total molar content of Q is 0.01-0.06 moL
  • the total molar content of Cu is 0.02-0.09 mol
  • the total molar content of the doped metal elements is 0 to 0.13 mol, and can be optionally 0 to 0.1 mol.
  • the disordered arrangement of metal elements in the transition metal layer contained in each nickel-iron-manganese-based sodium positive electrode active material and the distance between the transition metal layer and the sodium layer can be further adjusted to further improve the DC internal resistance (DCR) stability performance of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charge and discharge process.
  • DCR DC internal resistance
  • the ratio of the total molar content of the Na element to the total molar content of other metal elements in the positive electrode material composition of the embodiments of the present application in the above embodiments is (0.81-0.89):1, which can be optionally (0.82-0.89):1. In the exemplary examples, it can be 0.81:1, 0.82:1, 0.83:1, 0.84:1, 0.85:1, 0.86:1, 0.87:1, 0.88:1, 0.89:1 and other typical but non-limiting molar ratios or the range between any two molar ratios.
  • the content of sodium ions can be further adjusted, and the content of sodium ions that can be inserted and extracted from the nickel-iron-manganese-based sodium positive electrode active material can be increased, thereby improving the reversible capacity of the positive electrode material composition of the embodiment of the present application; moreover, the sodium ions in this content range can increase the O3 crystal phase content of each nickel-iron-manganese-based sodium positive electrode active material, so that each nickel-iron-manganese-based sodium positive electrode active material mainly presents O3 crystals, thereby improving the structural stability of the nickel-iron-manganese-based sodium positive electrode active material to improve its cycle performance.
  • the nickel-iron-manganese-based sodium positive electrode active material contained in the positive electrode material composition of the present application in the above-mentioned embodiments is a sodium layered oxide positive electrode material. Therefore, each nickel-iron-manganese-based sodium positive electrode active material also contains oxygen atoms. The content of the oxygen atoms can be within the conventional content range of the sodium layered oxide positive electrode material.
  • the types and contents of elements in the positive electrode material composition and the nickel-iron-manganese-based sodium positive electrode active material contained therein can be detected by inductively coupled plasma emission spectroscopy (ICP) using the Agilent ICP-OES730 described below.
  • the physical mixing ratio of at least two nickel-iron-manganese-based sodium positive electrode active materials contained in the positive electrode material composition of the embodiment of the present application in the above-mentioned embodiments can be adjusted according to the total molar content range of each element in the positive electrode material composition of the embodiment of the present application per unit molar amount.
  • the Cu element and Q element contained in the positive electrode material composition of the embodiment of the present application in the above-mentioned embodiments are distributed in different nickel-iron-manganese-based sodium positive electrode active materials.
  • the nickel-iron-manganese-based sodium positive electrode active material containing the Cu element has a relatively high structural stability during the charge and discharge process, thereby improving the cycle performance of the positive electrode material composition of the embodiment of the present application;
  • the nickel-iron-manganese-based sodium positive electrode active material containing the Q element has a relatively high gram capacity, thereby improving the gram capacity of the positive electrode material composition of the embodiment of the present application.
  • the compounding of the nickel-iron-manganese-based sodium positive electrode active material containing the Cu element and the nickel-iron-manganese-based sodium positive electrode active material containing the Q element to form a mixture can balance the gram capacity and cycle performance of the positive electrode material composition of the embodiment of the present application, thereby correspondingly balancing the energy density and cycle performance of the battery electrical properties. At the same time, it can also further improve the DC internal resistance (DCR) stability performance of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charge and discharge process to alleviate the growth of the DCR of the battery cell during the charge and discharge process.
  • DCR DC internal resistance
  • Cu element and Q element can also be distributed in the same nickel-iron-manganese-based sodium positive electrode active material.
  • the powder Dv50 particle size of the nickel-iron-manganese-based sodium cathode active material containing the above-mentioned Q element can be 3 to 8 ⁇ m, and can be optionally 4 to 6.5 ⁇ m.
  • the Dv50 particle size can be 3 ⁇ m, 4 ⁇ m, 4.5 ⁇ m, 5 ⁇ m, 5.5 ⁇ m, 6 ⁇ m, 6.5 ⁇ m, 7 ⁇ m, 7.5 ⁇ m, 8 ⁇ m and other typical but non-limiting particle sizes or the range between any two particle size values.
  • the Dv90 particle size of the nickel-iron-manganese-based sodium cathode active material containing the above-mentioned Q element can be 8 to 16 ⁇ m, and can be optionally 10 to 14 ⁇ m.
  • the Dv90 particle size can be 8 ⁇ m, 9 ⁇ m, 10 ⁇ m, 11 ⁇ m, 12 ⁇ m, 13 ⁇ m, 14 ⁇ m, 15 ⁇ m, 16 ⁇ m and other typical but non-limiting particle sizes or a range between any two particle size values.
  • the powder Dv50 particle size of the nickel-iron-manganese-based sodium cathode active material containing the above-mentioned Cu element can be 5 to 11 ⁇ m, and can be optionally 6.5 to 10 ⁇ m.
  • the Dv50 particle size can be 5 ⁇ m, 5.5 ⁇ m, 6 ⁇ m, 6.5 ⁇ m, 7 ⁇ m, 7.5 ⁇ m, 8 ⁇ m, 8.5 ⁇ m, 9 ⁇ m, 9.5 ⁇ m, 10 ⁇ m, 10.5 ⁇ m, 11 ⁇ m and other typical but non-limiting particle sizes or the range between any two particle size values.
  • the powder Dv90 particle size of the nickel-iron-manganese-based sodium cathode active material containing the above-mentioned Cu element can be 13 to 19 ⁇ m, and can be optionally 14.5 to 18 ⁇ m.
  • the Dv90 particle size can be 13 ⁇ m, 14 ⁇ m, 14.5 ⁇ m, 15 ⁇ m, 16 ⁇ m, 17 ⁇ m, 18 ⁇ m, 19 ⁇ m and other typical but non-limiting particle sizes or a range between any two particle size values.
  • the Dv50 particle size refers to the particle size corresponding to the cumulative particle size distribution percentage in the nickel-iron-manganese-based sodium positive electrode active material powder containing the above-mentioned Q element or Cu element reaches 50%.
  • the Dv90 particle size refers to the particle size corresponding to the cumulative particle size distribution percentage in the nickel-iron-manganese-based sodium positive electrode active material powder containing the above-mentioned Q element or Cu element reaches 90%.
  • Dv50 and Dv90 can be measured separately for the Dv50 and Dv90 particle sizes of each nickel-iron-manganese-based sodium positive electrode active material according to the method steps in GB/T16418.
  • the Dv50 particle size and Dv90 particle size in the above range can improve the compounding effect between the nickel-iron-manganese-based sodium positive electrode active material containing the above Q element and the nickel-iron-manganese-based sodium positive electrode active material containing the above Cu element, and further improve the DC internal resistance (DCR) stability performance of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charging and discharging process, so as to alleviate the growth of the DCR of the battery cell during the charging and discharging process.
  • DCR DC internal resistance
  • it has a suitable specific surface area to improve the stability of the contact interface between the positive electrode sheet and the electrolyte.
  • the specific surface area (BET) of the nickel-iron-manganese-based sodium cathode active material particles containing the above-mentioned Q element is 0.4-1.0 m 2 /g, and can be optionally 0.6-0.9 m 2 /g.
  • it can be 0.4 m 2 /g, 0.5 m 2 /g, 0.6 m 2 /g, 0.7 m 2 /g, 0.8 m 2 /g, 0.9 m 2 /g, 1.0 m 2 /g and other typical but non-limiting specific surface areas or the range between any two specific surface area values.
  • the specific surface area (BET) of the nickel-iron-manganese-based sodium positive electrode active material particles containing the Cu element is 0.4-0.7 m 2 /g, and can be 0.5-0.6 m 2 /g. In the exemplary embodiment, it can be 0.4 m 2 /g, 0.5 m 2 /g, 0.55 m 2 /g, Typical but non-limiting specific surface areas are 0.6 m 2 /g, 0.7 m 2 /g, etc., or a range between any two specific surface area values.
  • the specific surface area of the nickel-iron-manganese-based sodium positive electrode active material containing the Q element and the nickel-iron-manganese-based sodium positive electrode active material containing the Cu element in this range can improve the stability of the contact interface between the nickel-iron-manganese-based sodium positive electrode active material containing the Q element and the nickel-iron-manganese-based sodium positive electrode active material containing the Cu element and the electrolyte, and further improve the DC internal resistance (DCR) stability performance of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charging and discharging process.
  • DCR DC internal resistance
  • the compaction density of the nickel-iron-manganese-based sodium cathode active material powder containing the above-mentioned Q element under a pressure of 3 tons is higher than 3.1 g/cm 3 , and can be selected as 3.1-3.4 g/cm 3.
  • the compaction density under a pressure of 3 tons can be 3.1 g/cm 3 , 3.2 g/cm 3 , 3.3 g/cm 3 , 3.4 g/cm 3 , etc., which are typical but non-limiting compaction densities, or a range between any two compaction density values.
  • the compaction density of the nickel-iron-manganese-based sodium cathode active material powder containing the above-mentioned Cu element under a pressure of 3 tons may be 3.0-3.3 g/cm 3 , and may be 3.0-3.25 g/cm 3 .
  • the compaction density under a pressure of 3 tons may be 3 g/cm 3 , 3.1 g/cm 3 , 3.15 g/cm 3 , 3.2 g/cm 3 , 3.25 g/cm 3 , 3.3 g/cm 3 or other typical but non-limiting compaction densities or a range between any two compaction density values.
  • the specific surface area of the nickel-iron-manganese-based sodium positive electrode active material containing Q element and the nickel-iron-manganese-based sodium positive electrode active material containing Cu element in this range can improve the stability of the contact interface between the nickel-iron-manganese-based sodium positive electrode active material containing Q element and the nickel-iron-manganese-based sodium positive electrode active material containing Cu element and the electrolyte, and further improve the DC internal resistance (DCR) stability performance of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charge and discharge process.
  • DCR DC internal resistance
  • the gram capacity of the battery containing the nickel-iron-manganese-based sodium positive electrode active material containing Q element and the nickel-iron-manganese-based sodium positive electrode active material containing Cu element can be further improved.
  • mm is the sample weight in grams (g); HH is the thickness of the sample after compaction in millimeters (mm); SS is the cross-sectional area of the top column in square centimeters (cm 2 ).
  • At least two nickel-iron-manganese-based sodium positive electrode active materials contained in the positive electrode material composition of the present application in the above-mentioned embodiments can be physically mixed in a molar ratio of 0.5 to 28:1 of the nickel-iron-manganese-based sodium positive electrode active material containing the Cu element and the nickel-iron-manganese-based sodium positive electrode active material containing the Q element, and can be optionally 0.5 to 18:1.
  • it can be a typical but non-limiting molar ratio of 0.5:1, 1:1, 3:1, 5:1, 8:1, 10:1, 13:1, 15:1, 18:1, 20:1, 23:1, 25:1, 28:1, or a range between any two molar ratios.
  • the molar ratio of the nickel-iron-manganese-based sodium positive electrode active material can be 0.5 to 28:1.
  • the nickel-iron-manganese-based sodium positive electrode active material containing the Cu element is added to the nickel-iron-manganese-based sodium positive electrode active material containing the Q element, the total molar ratio of the nickel-iron-manganese-based sodium positive electrode active material containing the Q element is within the above-mentioned physical mixing molar ratio range.
  • the compounding effect between the nickel-iron-manganese-based sodium positive electrode active materials can be fully utilized, and the DCR stability performance of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charge and discharge process can be improved.
  • the gram capacity and cycle performance of the battery of the positive electrode material composition of the embodiment of the present application can be further balanced, thereby improving the energy density and cycle performance of the corresponding battery cell.
  • the nickel-iron-manganese-based sodium positive electrode active material contained in the positive electrode material composition of the embodiment of the present application in the above-mentioned embodiments is selected from O3 phase layered metal oxide.
  • the O3 phase layered metal oxide refers to a layered oxide with a crystalline structure in which the oxygen contained therein is stacked in an ABCABC type manner.
  • the nickel-iron-manganese-based sodium positive electrode active material contained in the positive electrode material composition of the embodiment of the present application in the above-mentioned embodiments is mainly O3 crystal phase, and the weight content of the O3 crystal phase in each nickel-iron-manganese-based sodium positive electrode active material can be more than 95%, further more than 98%, and can also reach 100%. The higher the weight proportion of the O3 crystal phase in each nickel-iron-manganese-based sodium positive electrode active material, the more desirable it is.
  • each nickel-iron-manganese-based sodium positive electrode active material has a relatively high structural stability, such as a relatively high structural stability relative to the P2 phase layered metal oxide, and its cycle performance is higher. At the same time, it can further improve the stability of the DCR of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charge and discharge process.
  • the above nickel-iron-manganese-based sodium cathode active material crystals include single crystals, and the single crystals are in block shape.
  • the discharge capacity in grams of the positive electrode material composition of the embodiments of the present application at 1.5-4.2V and 0.1C in the above-mentioned embodiments can reach 115-128mAh/g, and can be optionally 120-128mAh/g.
  • the charge gram capacity and discharge gram capacity of the positive electrode material composition of the embodiment of the present application are specifically prepared by preparing the positive electrode material composition of the embodiment of the present application into a positive electrode, and assembling it with the negative electrode into a sodium ion button battery, and detecting the gram capacity of the sodium ion button battery.
  • the sodium ion button cell used to detect the charge gram capacity and discharge gram capacity of the positive electrode material composition of the embodiment of the present application is assembled according to the following method:
  • Positive electrode sheet The positive electrode material composition of the embodiment of the present application is used as the positive electrode active material, and the conductive agent carbon nanotubes, the conductive agent carbon black, and the binder polyvinylidene fluoride (PVDF) are fully stirred and mixed in an appropriate amount of solvent NMP at a weight ratio of 95:0.5:2:2.5 to form a uniform positive electrode slurry; the positive electrode slurry is evenly coated on the surface of the 13 ⁇ m positive electrode current collector aluminum foil, and after drying and cold pressing, a positive electrode sheet is obtained;
  • PVDF polyvinylidene fluoride
  • Negative electrode sheet hard carbon, conductive agent SP, and CMC binder are added to deionized water in a weight ratio of 8:1:1 and stirred thoroughly to form a uniform negative electrode slurry; the negative electrode slurry is evenly coated on the surface of a 6 ⁇ m copper foil, and after drying and cold pressing, a negative electrode sheet is obtained;
  • Electrolyte 1M NaPF 6 /(EC/DEC, volume ratio 1:1);
  • Diaphragm Glass fiber
  • Sodium ion button cell assembly The above-mentioned positive electrode sheet, glass fiber film and negative electrode sheet are stacked in order to form a button cell assembly after assembly.
  • the electrode assembly is placed in a packaging shell, and 1M NaPF 6 /(EC/DEC, volume ratio 1:1) electrolyte is added. After packaging, formation, standing and other processes, a sodium ion button cell is obtained.
  • the present application provides a method for preparing the positive electrode material composition of the above-mentioned embodiment of the present application.
  • the method for preparing the positive electrode material composition of the present application embodiment comprises the following steps:
  • S10 physically mixing at least two nickel-iron-manganese-based sodium positive electrode active materials according to the molar content ratio of Na, Ni, Mn, Fe, Q and Cu contained in the positive electrode material composition per unit mole to form a positive electrode material composition.
  • the nickel-iron-manganese-based sodium positive electrode active material is the nickel-iron-manganese-based sodium positive electrode active material contained in the positive electrode material composition of the embodiment of the present application, therefore,
  • the physical mixing of at least two nickel-iron-manganese-based sodium positive electrode active materials also refers to physical intermixing and amorphous phase doping.
  • the mixing ratio of at least two nickel-iron-manganese-based sodium positive electrode active materials needs to satisfy the content of Na, Ni, Mn, Fe, Cu, and Q elements in the positive electrode material composition of the above application embodiment per unit mole to meet the range described above, specifically:
  • the total molar content of Na is 0.78 to 1 moL, and can be selected as 0.8 to 1 moL;
  • the total molar content of Ni is 0.12-0.38 mol, and can be selected as 0.15-0.35 mol;
  • the total molar content of Mn is 0.18-0.48 mol, and can be selected as 0.20-0.45 mol;
  • the total molar content of Fe is 0.18-0.35 mol, and can be selected as 0.20-0.33 mol;
  • the total molar content of Q is 0.01 to 0.12 moL, and can be optionally 0.01 to 0.1 moL;
  • the total molar content of Cu is 0.01 to 0.14 moL, and can be optionally 0.01 to 0.12 moL.
  • the preparation method of the positive electrode material composition of the embodiment of the present application is to mix at least two nickel-iron-manganese-based sodium positive electrode active materials according to the proportion of the content range of Na, Ni, Mn, Fe, Cu, and Q elements, so that the direct current internal resistance (DCR) of the battery cell containing the positive electrode material composition of the embodiment of the present application is relatively stable during the charging and discharging process, and the DCR growth rate of the battery cell during the charging and discharging process can be significantly reduced. It also makes the positive electrode material composition of the embodiment of the present application have high gram capacity and cycle performance.
  • the nickel-iron-manganese-based sodium positive electrode active material of step S10 can be obtained from existing nickel-iron-manganese-based sodium positive electrode active materials, and of course, it can also be a nickel-iron-manganese-based sodium positive electrode active material that is improved according to the type and content of elements contained in the positive electrode material composition of the embodiment of the application.
  • the nickel-iron-manganese-based sodium positive electrode active material in step S10 can be prepared according to the following method:
  • S11 providing each nickel-iron-manganese-based sodium positive electrode active material precursor according to the element ratio contained in each nickel-iron-manganese-based sodium positive electrode active material;
  • each nickel-iron-manganese-based sodium positive electrode active material is sintered separately to obtain each nickel-iron-manganese-based sodium positive electrode active material.
  • the nickel-iron-manganese-based sodium positive electrode active material precursor can be a mixture in proportion containing a sodium source, a nickel source, a manganese source, an iron source and further containing a copper source and a metal element source shown in Q, or further contains the doped metal source contained in the nickel-iron-manganese-based sodium positive electrode active material in the positive electrode material composition of the embodiment of the present application.
  • the nickel-iron-manganese-based sodium cathode active material precursor can be prepared by a solid phase method or a precipitation method.
  • the nickel-iron-manganese-based sodium cathode active material precursor can be prepared according to a method comprising the following steps:
  • Step S111 According to the stoichiometric ratio of elements in the nickel-iron-manganese-based sodium cathode active material, a sodium source, a nickel source, a manganese source, an iron source, a copper source, at least one of the metal element sources represented by Q, or further a doping element source is subjected to solid phase mixing treatment to obtain a nickel-iron-manganese-based sodium cathode active material precursor.
  • the solid phase mixing treatment is relative to the liquid phase mixing, which generally means that no solvent is added during the mixing process, such as no water is added, and the source solids in step S111 are dry mixed under solvent-free conditions.
  • the source compounds other than the sodium source in step S111 can be mixed first, and then the sodium source is added for re-mixing, so as to improve the uniformity of mixing of the sources and improve the safety of the solid phase mixing process.
  • the solid phase mixing treatment can be coated but not limited to ball milling treatment. Any method that can improve the uniform mixing of the source compounds in step S111 is within the scope disclosed in the embodiment of the present application.
  • the ball milling rate can be controlled to be 300 to 1000 rpm, and can be optionally 400 to 600 rpm; the ball milling time can be 1h to 6h, and can be optionally 2h to 4h.
  • the mixing uniformity of each source can be improved, thereby ultimately improving the stability of the structure and electrochemical properties of the nickel-iron-manganese-based sodium cathode active material in step S12.
  • the sodium source may be a sodium salt, such as at least one of sodium carbonate, sodium hydroxide, and the like.
  • the nickel source may be a soluble or insoluble nickel compound, such as nickel oxide (NiO) or a nickel salt.
  • the nickel salt may include at least one of nickel nitrate, nickel carbonate, nickel hydroxide, nickel sulfate and the like.
  • the manganese source may be a soluble or insoluble manganese compound, such as manganese oxide (Mn 2 O 3 ) or a manganese salt, etc.
  • the manganese salt may include at least one of manganese nitrate, manganese carbonate, manganese hydroxide, manganese sulfate, etc.
  • the iron source may be a soluble or insoluble iron compound, such as iron oxide (such as Fe 2 O 3 ) or iron salt, etc.
  • the iron salt may include at least one of iron nitrate, iron carbonate, iron hydroxide, iron sulfate, etc.
  • the copper source may be a soluble or insoluble copper compound, such as copper oxide (such as CuO) or copper salt, etc.
  • the copper salt may include at least one of copper nitrate, copper carbonate, copper hydroxide, copper sulfate, etc.
  • the metal element source and the doping metal element source shown in Q may be soluble or insoluble compounds of the metal element and the doping metal element shown in Q, such as oxides of the metal element and the doping metal element shown in Q or salts of the metal element and the doping metal element shown in Q.
  • the salts of the metal element and the doping metal element shown in Q may include at least one of nitrates, carbonates, hydroxides, sulfates, etc. of the metal element and the doping metal element shown in Q.
  • the types of the above-mentioned sodium source, nickel source, manganese source, iron source, copper source and the metal elements and doped metal element sources shown in Q can be effectively mixed evenly during the mixing process, thereby improving the structure and chemical stability of each nickel-iron-manganese-based sodium cathode active material precursor to generate nickel-iron-manganese-based sodium cathode active material.
  • nickel-iron-manganese-based sodium cathode active material precursor When the nickel-iron-manganese-based sodium cathode active material precursor is prepared by precipitation method, it can be prepared according to the method including the following steps:
  • Step S113 according to the stoichiometric ratio of elements in the nickel-iron-manganese-based sodium positive electrode active material, a soluble nickel source, a soluble manganese source, a soluble iron source and a copper source, at least one of the metal element sources represented by Q or further a doping element source is prepared into a mixed solution, and at least one of a precipitant and a complexing agent is added to perform a co-precipitation treatment to obtain a precipitated mixture;
  • Step S114 mixing the precipitated mixture with a sodium source to obtain a nickel-iron-manganese-based sodium cathode active material precursor.
  • At least one of the precipitant and the complexing agent should be a compound that can precipitate nickel, manganese, iron, copper, metal elements shown in Q, and doping metal elements in the nickel source, soluble manganese source, soluble iron source, soluble copper source, metal element source shown in Q, and doping element source.
  • the precipitant and complexing agent in step S113 may be the same or different.
  • the precipitant may include at least one of alkali metal hydroxides, carbonates, etc.
  • the complexing agent may include an inorganic or organic complexing agent.
  • the inorganic complexing agent may include at least one of ammonia water, ammonium bicarbonate, ammonium sulfate, ammonium carbonate, etc.; the organic complexing agent may include at least one of citric acid, tartaric acid, disodium ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid (EDTA), aminotriacetic acid (NTA), etc.
  • precipitants and complexing agents can effectively precipitate nickel, manganese, iron, copper and the metal elements represented by Q as well as doping elements.
  • At least one of the precipitant and the complexing agent should be in excess relative to the total amount of metal elements contained in the mixed solution, such as the total molar amount, to ensure that all metal elements contained in the mixed solution are fully precipitated to improve the accuracy of the stoichiometric ratio of the metal elements contained in the nickel-iron-manganese-based sodium cathode active material precursor.
  • the soluble nickel source may include at least one of nickel acetate, nickel chloride, nickel nitrate, and nickel sulfate.
  • the soluble manganese source may include at least one of manganese nitrate, manganese sulfate, and manganese halide.
  • the soluble iron source may include at least one of iron nitrate, manganese sulfate, and halides.
  • the soluble copper source may include at least one of iron nitrate, manganese sulfate, halide, and the like.
  • the soluble metal element Q and the doping metal element source may include at least one of the metal element Q and the doping metal element's nitrate, manganese sulfate, halide, etc.
  • the types of the above-mentioned soluble nickel source, soluble manganese source, soluble iron source, soluble copper source and soluble metal elements represented by Q and doping element sources all have good solubility and can quantitatively control the stoichiometric ratio of each metal element in the precipitation mixture.
  • the mixing ratio between the sodium source and the precipitation mixture in step S114 should satisfy the content of sodium ions in the nickel-iron-manganese-based sodium positive electrode active material, that is, the sodium layered oxide, specifically the stoichiometric ratio required by the sodium element in the O3 crystalline layered oxide.
  • the mixing process can be a solid phase mixing process or dissolving a soluble sodium source and mixing it with the precipitation mixture, and then removing the solvent.
  • the sodium source in step S114 may be a sodium salt, such as at least one of sodium carbonate, sodium hydroxide, etc.
  • step S12 after sintering the at least two nickel-iron-manganese-based sodium cathode active material precursors in step S11, each nickel-iron-manganese-based sodium cathode active material will be generated.
  • the sintering conditions have a certain influence on the structural stability and electrochemical properties of the generated nickel-iron-manganese-based sodium cathode active material.
  • the sintering temperature can be controlled at 700-980°C, optionally 750-950°C. In the demonstration example, it can be 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 980°C, etc. Typical but non-restrictive temperatures or a range between any two temperature values.
  • the sintering time can be 4h to 20h, and can be 6h to 12h. In the exemplary embodiment, it can be 4h, 5h, 8h, 10h, 12h, 15h, 18h, 20h and other typical but non-limiting hours or any range between two hours.
  • the precursors of the nickel-iron-manganese-based sodium positive electrode active materials in step S11 can be reacted to generate the nickel-iron-manganese-based sodium positive electrode active materials respectively, and the synergistic effect of the physical mixing and compounding of the nickel-iron-manganese-based sodium positive electrode active materials can be further improved, and the DC internal resistance (DCR) stability of the battery cell containing the positive electrode material composition of the embodiment of the present application during the charging and discharging process can be further improved, and the electrochemical properties such as the energy density and cycle performance of the battery cell can also be improved.
  • DCR DC internal resistance
  • the temperature of the sintering treatment can be heated to the temperature of the sintering treatment at a heating rate of 2 to 20°C/min.
  • the heating rate can be further controlled to be 5 to 15°C/min.
  • the heating rate can be a typical but non-limiting rate such as 2°C/min, 4°C/min, 5°C/min, 6°C/min, 8°C/min, 10°C/min, 12°C/min, 15°C/min, 17°C/min, 18°C/min, 20°C/min, or a range between any two rate values.
  • the sintering process in the above step S12 should be understood to be carried out in an aerobic environment.
  • the sintering process can be carried out in air or in an oxygen-containing protective atmosphere, such as oxygen-containing nitrogen or other inert atmospheres.
  • the embodiments of the present application provide a positive electrode.
  • the positive electrode of the embodiments of the present application includes a current collector and a positive electrode active material layer.
  • the positive electrode active material layer is combined with the current collector, and the positive electrode active material layer contains the positive electrode material composition of the embodiments of the present application.
  • the current collector refers to a structure for collecting current and for transmitting electrons.
  • the positive electrode active material layer refers to a layer structure containing a positive electrode active material, which is a key substance participating in the battery chemical reaction in the positive electrode.
  • the positive electrode active material includes the positive electrode material composition of the embodiment of the present application.
  • the positive electrode active material layer is combined with the current collector, which means that the positive electrode active material layer is at least combined with the surface of the current collector.
  • the positive electrode can be a pole piece, which means that the positive electrode has a sheet-like morphology. Of course, it can also be set to other morphologies as needed.
  • the positive electrode active material layer of the positive electrode of the embodiment of the present application contains the positive electrode material composition of the embodiment of the present application, it has been tested that the direct current internal resistance (DCR) of the battery cell containing the positive electrode of the embodiment of the present application during the charging and discharging process is relatively stable, and the DCR growth rate of the battery cell during the charging and discharging process can be significantly reduced. At the same time, the battery cell has a high energy density and good cycle performance.
  • DCR direct current internal resistance
  • the current collector contained in the positive electrode of the embodiment of the present application includes but is not limited to a metal current collector, a carbon current collector, a conductive resin current collector, a composite current collector of metal and resin, etc., more specifically, aluminum, copper, nickel, titanium, iron and their respective alloys, stainless steel, carbon fiber, carbon nanotubes (CNT), graphite, etc.
  • the current collector can also be a dense film layer or a film layer with a porous structure.
  • the current collector can be but is not limited to aluminum foil or porous aluminum foil, etc.
  • the positive electrode active material layer contained in the positive electrode of the embodiment of the present application is combined with the current collector and can be at least stacked on the surface of the current collector.
  • the positive electrode active material layer can be at least partially embedded in the current collector.
  • the positive electrode active material layer is at least bonded to the surface of the current collector and may be a structure as shown in FIG1 , where the positive electrode active material layer 12 is stacked on one surface of the current collector 11.
  • the positive electrode active material layer 12 may be further extended into the porous structure of the current collector 11 in addition to being stacked and bonded to the surface of the current collector 11.
  • the positive electrode active material layer is at least combined with the surface of the current collector and may be a structure as shown in FIG2 , where the current collector 11 has two surfaces arranged opposite to each other, and the positive electrode active material layer 12 is stacked on the two surfaces arranged opposite to each other of the current collector 11.
  • the positive electrode active material layer 12 may be further extended into the porous structure of the current collector 11 in addition to being stacked and combined on the two surfaces of the current collector 11.
  • the mass content of the total mass of the positive electrode material composition of the above-mentioned embodiment of the present application in the positive electrode active material layer can be 90% to 97%, optionally 94% to 96.5%, and in the exemplary embodiment, it can be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97% and other typical but non-limiting contents or the range between any two content values.
  • the positive electrode material composition in this content range can effectively improve the energy density of the positive electrode and has good cyclability.
  • the positive electrode active material layer contained in the positive electrode of each application embodiment generally includes components such as a binder and a conductive agent.
  • the binder can enhance the mechanical properties between the positive electrode active material layer itself and the current collector.
  • the conductive agent can effectively improve the conductivity of the positive electrode, such as reducing the resistance of the positive electrode.
  • the mass content of the binder contained in the above-mentioned positive electrode active material layer can be 0.5% to 5%, optionally 1% to 3%. In a demonstration example, it can be 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.8%, 3%, 3.5%, 4%, 4.5%, 5% and other typical but non-limiting contents or the range between any two content values.
  • the binder may include one or more of an oil-soluble binder, a water-soluble binder, an emulsion-type binder, etc.
  • the oil-soluble binder may include one or more of polyvinylidene fluoride, polyimide, polytetrafluoroethylene, polybutyl acrylate, polyacrylonitrile, etc.
  • the water-soluble binder may include one or more of carboxymethyl cellulose, carboxymethyl cellulose salt, polyacrylic acid, polyacrylic acid salt, polyvinyl alcohol, sodium alginate, cyclodextrin, etc.
  • the emulsion-type binder may include one or more of styrene-butadiene rubber, vinyl acetate resin, acrylic resin, and chlorinated rubber.
  • the content within this range and the above-mentioned types of binders can effectively enhance the mechanical properties of the positive electrode active material layer and the bonding strength between the positive electrode and the current collector, and can effectively improve the cycle performance of the positive electrode.
  • the mass content of the conductive agent contained in the above-mentioned positive electrode active material layer can be 0.5% to 5%, optionally 1% to 3%. In a demonstration example, it can be 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.8%, 3%, 3.5%, 4%, 4.5%, 5% and other typical but non-limiting contents or a range between any two content values.
  • the conductive agent may include at least one of a granular conductive agent, a linear conductive agent, etc.
  • the granular conductive agent may include one or more of acetylene black (SP), conductive carbon black (super-P), Ketjen black, graphene, etc.
  • the linear conductive agent may include one or more of carbon nanotubes, carbon fibers, conductive oxide nanowires, etc.
  • the granular conductive agent is a conductive agent with a nonlinear particle morphology relative to a linear conductive agent.
  • a linear conductive agent refers to a conductive agent with a one-dimensional fiber morphology.
  • the content within this range and the above-mentioned types of conductive agents can effectively improve the conductivity of the positive electrode active material layer.
  • the conductive agent contained in the positive electrode active material layer in the positive electrode of each embodiment above includes a linear conductive agent and a granular conductive agent.
  • the mass content of the linear conductive agent in the positive electrode active material layer is 0.1% to 2.5%, and can be 0.3% to 0.7%. In the exemplary embodiment, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, etc., which are typical but non-limiting contents or the range between any two content values.
  • the crystals of the nickel-iron-manganese-based sodium positive electrode active material contained in the positive electrode material composition of the above text application embodiment include single crystals, and the morphology of the single crystal is blocky, therefore, a linear conductive agent is added to the positive electrode active material layer, and the content of the linear conductive agent is controlled within this range, so that the linear conductive agent can form a rich conductive network structure in the positive electrode active material layer, and the linear conductive agent can also be entangled on the surface of the blocky single crystal particles.
  • the granular conductive agent can be effectively dispersed in the gaps of the positive electrode material composition.
  • the linear conductive agent constructs a long-range conductive network structure in the positive electrode active material layer, and the granular conductive agent constitutes a short-range conductive structure. Therefore, the conductive synergistic effect of the linear conductive agent and the granular conductive agent in the positive electrode active material layer effectively improves the conductivity of the positive electrode active material layer, can significantly reduce the internal resistance of the positive electrode, and is also conducive to improving the DCR stability of the battery electrical properties during the charging and discharging process.
  • the aspect ratio of the linear conductive agent can be controlled to be 40 to 3000:1, and can be 50 to 2500:1.
  • the aspect ratio can be 40:1, 50:1, 100:1, 500:1, 1000:1, 1500:1, 2000:1, 2500:1, 3000:1, etc., which are typical but non-limiting aspect ratios, or a range between any two aspect ratios.
  • the aspect ratio refers to the ratio of the length to the diameter of the linear conductive agent.
  • the length of the linear conductive agent can be selected to be 0.5 to 5 ⁇ m, or optionally 0.5 to 2 ⁇ m. In the exemplary embodiment, it can be 0.5 ⁇ m, 1 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 3 ⁇ m, 3.5 ⁇ m, 4 ⁇ m, 4.5 ⁇ m, 5 ⁇ m, etc. typical but non-limiting lengths or a range between any two length values.
  • the diameter of the linear conductive agent can be selected to be 2 to 10 nm, or optionally 3 to 7 nm.
  • the diameter can be 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, etc., which are typical but non-limiting diameters, or a range between any two diameter values.
  • the linear conductive agent can construct a richer long-range conductive network structure in the positive electrode active material layer, further enhancing the conductive synergistic effect of the linear conductive agent and the particulate conductive agent, so as to further improve the conductivity of the positive electrode active material layer.
  • the positive electrode active material layer in the positive electrode of each embodiment above may contain other additives in addition to the positive electrode active material, binder and conductive agent.
  • the additives may include but are not limited to functional components such as sodium supplement additives.
  • the content of the positive electrode active material layer on a single side of the current collector in the above embodiments, i.e., the coating weight (CW) is 260-350 mg/1540.25 mm 2 , and can be optionally 280-320 mg/1540.25 mm 2 .
  • the coating weight refers to the weight of the positive electrode active material layer per unit area. The coating weight in this range can effectively stabilize the DC internal resistance (DCR) of the battery cell during the charge and discharge process and improve the energy density of the battery cell.
  • DCR DC internal resistance
  • the compaction density of the positive electrode active material layer in the above embodiments can be 2.6-3.4 g/cm 3 , and can be 2.8-3.2 g/cm 3. In the exemplary examples, it can be 2.6 g/cm 3 , 2.7 g/cm 3 , 2.8 g/cm 3, 2.9 g/cm 3 , 3.0 g/cm 3 , 3.1 g/cm 3 , 3.2 g/cm 3 , 3.3 g/cm 3 , 3.4 g/cm 3 , etc., typical but non-limiting compaction densities or a range between any two compaction density values.
  • the compaction density refers to the weight of the positive electrode active material layer per unit volume.
  • the compaction density in this range can effectively improve the stability of the contact interface between the positive electrode and the electrolyte, and improve the relative stability of the DC internal resistance (DCR) of the battery cell during the charge and discharge process and the energy density of the battery cell.
  • DCR DC internal resistance
  • the porosity of the positive electrode active material layer in the above embodiments may be 40% to 70%, and may be 50% to 65%. In the exemplary embodiments, it may be 40%, 43%, 45%, 48%, 50%, 53%, 55%, 58%, 60%, 63%, 65%, 70% and other typical but non-limiting porosities or the range between any two porosity values.
  • the porosity refers to the total volume of pores contained in the unit volume of the positive electrode active material layer and the percentage of the unit volume of the positive electrode active material layer.
  • the porosity in this range enables the positive electrode active material layer to have the above-mentioned compaction density, further improves the electrolyte wettability of the positive electrode and improves the stability of the contact interface with the electrolyte, and improves the relative stability of the DC internal resistance (DCR) of the battery cell during the charge and discharge process and the energy density of the battery cell.
  • the porosity of the positive electrode active material layer (pole piece) in the above embodiments can be detected according to the following method:
  • the detection is carried out by gas replacement method, with specific reference to GB/T24586-2009.
  • the specific steps of the pole piece porosity detection method are as follows: the positive electrodes in each battery monomer in Example B1 to Example B17 and Comparative Example B1 to Comparative Example B2 are respectively immersed in ethyl methyl carbonate (EMC) for cleaning, and then tested by the method specified in GB/T24586-2009.
  • EMC ethyl methyl carbonate
  • the gas replacement method is used, combined with Archimedes' principle and Bohr's law, to accurately measure the true volume of the material being tested, that is, the true volume of the sample, so as to obtain the porosity of the sample to be tested.
  • the positive electrode is a pole piece in the above embodiments
  • the film resistance of the positive electrode active material layer in the above embodiments can be 0.5-5m ⁇ , and can be 0.5-3m ⁇ . In the exemplary embodiment, it can be 0.5m ⁇ , 1m ⁇ , 1.5m ⁇ , 2m ⁇ , 2.5m ⁇ , 3m ⁇ , 3.5m ⁇ , 4m ⁇ , 4.5m ⁇ , 5m ⁇ , etc., which are typical but not limiting, or any two films
  • the electrode is a sheet-shaped morphology as described above, so it has two opposite surfaces.
  • the membrane resistance refers to the resistance value between one surface of the sheet-shaped positive electrode and the other opposite surface. The membrane resistance in this range can effectively improve the performance of the battery including efficiency and life.
  • the membrane resistance of the above electrode can be detected according to the following method:
  • the four-probe method is used for detection: the positive electrodes in each battery cell in Example B1 to Example B17 and Comparative Examples B1 to Comparative Examples B2 are respectively immersed in ethyl methyl carbonate (EMC) for cleaning, and tested by the method specified in GB/T 30835-2014 or T/CASAS 019-2021, and four copper plates with a length of 1.5 cm, a width of 1 cm, and a thickness of 2 mm are equidistantly fixed in a line, and the spacing between the two middle copper plates is L (1 cm to 2 cm), and the substrate for fixing the copper plates is an insulating material.
  • EMC ethyl methyl carbonate
  • the lower end faces of the four copper plates are pressed on the electrode to be tested, and a direct current I is connected to the copper plates at both ends, and a voltage V is measured at the two middle copper plates.
  • the I and V values are read three times, and the average value of I and V is taken, and V/I is the electrode sheet resistance at the test point.
  • the positive electrode in each of the above embodiments is a pole piece, and the ratio of the thickness from one surface of the pole piece to the other opposite surface to the thickness of the current collector is 7 to 15:1, and can be optionally 8 to 14:1. In the exemplary embodiment, it can be a typical but non-limiting ratio such as 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, or a range between any two ratios.
  • the thickness refers to the vertical distance from one surface of the layer structure to the other opposite surface.
  • the thickness from one surface of the pole piece to the other opposite surface refers to the sum of the thickness of one positive electrode active material layer plus the thickness of the current collector; when both surfaces of the current collector as shown in FIG2 contain positive electrode active material layers, the thickness from one surface of the pole piece to the other opposite surface refers to the sum of the thickness of two positive electrode active material layers plus the sum of the thickness of the current collector.
  • the thickness of the positive electrode active material layer contained in the pole piece can be controlled to be 85-221 ⁇ m, and further can be 117-182 ⁇ m. In the exemplary embodiment, it can be 85 ⁇ m, 90 ⁇ m, 100 ⁇ m, 110 ⁇ m, 117 ⁇ m, 120 ⁇ m, 130 ⁇ m, 140 ⁇ m, 150 ⁇ m, 160 ⁇ m, 170 ⁇ m, 180 ⁇ m, 182 ⁇ m, 190 ⁇ m, 200 ⁇ m, 210 ⁇ m, 220 ⁇ m, 221 ⁇ m, and other typical but non-limiting thicknesses or the range between any two thickness values. In the embodiment, the thickness of the current collector can be but is not limited to 13-15 ⁇ m.
  • the structure of the positive electrode active material layer contained in the pole piece can be effectively improved, such as regulating the pore structure, membrane resistance and capacity of the positive electrode active material layer, thereby further improving the electrolyte wettability of the positive electrode and improving the stability of the contact interface with the electrolyte, thereby improving the relative stability of the direct current internal resistance (DCR) of the battery cell during the charge and discharge process and the energy density of the battery cell and the electrochemical properties such as cycle performance.
  • DCR direct current internal resistance
  • the present application also provides a method for preparing the positive electrode of the above embodiment.
  • the method for preparing the positive electrode of the above embodiment comprises the following steps:
  • the positive electrode slurry is subjected to a film-forming treatment on the current collector to form a positive electrode active material layer, thereby obtaining a positive electrode.
  • the positive electrode active material in step S20 includes the positive electrode material composition of the embodiment of the present application.
  • the positive electrode active material, binder, conductive agent and other components in step S20 can be mixed according to the content ratio of the corresponding components contained in the positive electrode active material layer of the positive electrode.
  • the solvent can be an organic solvent or water suitable for preparing positive electrode slurry.
  • the mixing process in step S20 can be carried out according to the conventional electrode slurry preparation method, such as but not limited to stirring, until the components are evenly dispersed to form a stable positive electrode slurry.
  • the viscosity and other properties of the positive electrode slurry should meet the requirements of the film forming process so as to form a positive electrode active material layer that meets the quality requirements on the current collector.
  • the positive electrode active material layer prepared in step S30 is the positive electrode active material layer contained in the positive electrode of the above embodiment of the present application.
  • the positive electrode slurry may be film-formed on the current collector in accordance with a conventional positive electrode active material layer method.
  • the electrode slurry may be first formed into a wet film on the current collector; then a drying process is performed to volatilize the solvent, thereby drying the wet film; and then the dried film layer is roll-pressed to form a positive electrode active material layer, thereby obtaining a positive electrode.
  • the positive electrode active material layer can also be prepared by improving the conventional positive electrode active material layer preparation method, or by adopting a new method.
  • the electrode slurry in step S20 is used to prepare the positive electrode active material layer on the current collector, it is within the scope disclosed in the embodiment of the present application.
  • the film forming treatment conditions in S30 can be controlled and adjusted, such as the conditions for forming a wet film on the current collector of the positive electrode slurry configured in step S20, the conditions for the roller pressing treatment, etc., and the related properties of the formed positive electrode active material layer can be controlled and adjusted, such as controlling and adjusting the content of the positive electrode active material layer on a single side of the current collector to the range of 250 to 330 mg/1540.25 mm2 as described above, controlling and adjusting the compaction density to the range of 2.6 to 3.2 g/ cm3 as described above, controlling and adjusting the porosity to the range of 35% to 65% as described above, and controlling and adjusting the sheet resistance of the pole piece to the range of 0.5 to 5 m ⁇ as described above.
  • an embodiment of the present application also provides a sodium battery.
  • the sodium battery of the embodiment of the present application may include any one of a sodium battery cell, a battery module, and a battery pack.
  • a sodium battery cell is also called a sodium battery core, which includes a battery outer package and an electrode assembly encapsulated in the battery outer package.
  • the number of electrode assemblies contained in a battery cell can be one or more, which can be adjusted according to actual needs.
  • the outer packaging of the sodium battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.; it can also be a soft package, such as a bag-type soft package.
  • the material of the soft package can be plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.
  • the shape of the outer packaging can be cylindrical, square, or any other shape.
  • the shape of the outer packaging gives the shape of the sodium battery cell, so the shape of the sodium battery cell can also be cylindrical, square, or any other shape corresponding to the shape of the outer packaging.
  • the sodium battery cell can be a battery cell 20 with a square structure as shown in FIG. 3.
  • the outer packaging of the battery cell 20 may include a housing 21 and a cover plate 23.
  • the housing 21 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity.
  • the housing 21 has an opening connected to the receiving cavity, and the cover plate 23 is used to cover the opening to close the receiving cavity.
  • One or more electrode assemblies 22 are encapsulated in the receiving cavity.
  • the sodium battery cell may be a sodium battery cell containing an electrolyte, or a sodium battery cell containing a solid electrolyte.
  • the electrode assembly contained in the sodium battery cell generally includes a positive electrode, a negative electrode and a separator.
  • the positive electrode and the negative electrode are alternately stacked, and the separator is stacked between the positive electrode and the negative electrode to play an isolating role and separate the positive electrode from the negative electrode.
  • the positive electrode, the separator layer and the negative electrode can form an electrode assembly of a laminated structure through a lamination process, or can form an electrode assembly of a core structure through a winding process.
  • the electrode assembly containing the separator is placed in an outer package, the electrolyte is injected and the electrode assembly is soaked, and the sodium battery cell is obtained by packaging.
  • the electrode assembly contained in the sodium battery cell When it is a sodium battery cell containing a solid electrolyte, the electrode assembly contained in the sodium battery cell generally includes a positive electrode, a negative electrode and a solid electrolyte.
  • the positive electrode and the negative electrode are alternately stacked, and the solid electrolyte is stacked between the positive electrode and the negative electrode to play an isolating role, separating the positive electrode from the negative electrode.
  • the electrode assembly containing the solid electrolyte is placed in an outer package, and the sodium battery cell is obtained by packaging.
  • the positive electrode contained in the electrode assembly is the positive electrode of the above-mentioned application embodiment, that is, the positive electrode active material layer contains the positive electrode material composition of the above-mentioned application embodiment.
  • the electrode assembly contained in the sodium battery monomer of the present application embodiment has a stable contact interface with the electrolyte, and the DC internal resistance (DCR) during the charging and discharging process is relatively stable, and the DCR growth rate of the battery cell during the charging and discharging process is small.
  • the battery cell also has electrochemical properties such as high energy density and good cycle performance.
  • the negative electrode contained in the electrode assembly includes a negative electrode current collector, and optionally includes a negative electrode active material layer disposed on the surface of the negative electrode current collector, wherein the negative electrode active material layer contains a negative electrode active material.
  • the negative electrode current collector may include but is not limited to a metal or a composite current collector.
  • the metal sodium, sodium alloy, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc. may be used.
  • the negative electrode plate may not contain a negative electrode active material layer, and sodium or sodium alloy is both a current collector and a negative electrode active material.
  • the composite current collector may include a composite material of a polymer material and a metal, wherein the polymer material may include but is not limited to polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc., and the metal may include but is not limited to sodium, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy.
  • the composite current collector may be obtained by mixing a polymer material and a metal, or may be coated on at least one side of the polymer material by electroplating, coating or other methods.
  • the negative electrode active material in the negative electrode active material layer may include but is not limited to a mixture or composite material formed by any one or more of carbon-based materials, alloy materials, titanium-based materials, and sodium metal.
  • the carbon-based materials include but are not limited to one or more of graphite, soft carbon, hard carbon, carbon microspheres, and carbon fibers;
  • the alloy materials include but are not limited to one or more of sodium-tin alloys, sodium-germanium alloys, and sodium-antimony alloys; and the titanium-based materials include but are not limited to one or more of titanium dioxide, titanates, and titanium phosphates.
  • the mass content of the negative electrode active material in the negative electrode active material layer can be 85% to 98%, and can be optionally 95% to 98%. In the exemplary embodiment, it can be 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% and other typical but non-limiting contents or the range between any two content values.
  • the negative electrode active material layer may also include at least one of a conductive agent and a binder.
  • the conductive agent is used to collect current between the negative electrode active materials and between the active materials and the current collector to improve the electronic conductivity. At the same time, the conductive agent can also promote the infiltration of the electrolyte into the negative electrode sheet.
  • the binder can improve the bonding strength between the various substances in the negative electrode active material layer and between the active layer and the current collector.
  • the mass content of the conductive agent in the negative electrode active material layer can be 0.5% to 10%. In the exemplary embodiment, it can be 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% and other typical but non-limiting contents or a range between any two content values, and can also be set to other contents as needed.
  • the conductive agent includes one or more of acetylene black (SP), carbon nanotubes, conductive carbon black (super-P), Ketjen black, carbon fiber, and graphene.
  • the mass content of the binder in the negative electrode active material layer can be 0.5% to 10%. In the exemplary embodiment, it can be 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% and other typical but non-limiting contents or a range between any two content values, and can also be set to other contents as needed.
  • the binder includes but is not limited to polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, polyimide, polytetrafluoroethylene, polybutyl acrylate, polyacrylonitrile, carboxymethyl cellulose, carboxymethyl cellulose salt, polyacrylic acid, polyacrylate, polyvinyl alcohol, sodium alginate, cyclodextrin, styrene-butadiene rubber, vinyl acetate resin, acrylic resin, chlorinated rubber and one or more thereof.
  • the negative electrode active material layer may also optionally include a thickener, such as but not limited to carboxymethyl cellulose (CMC).
  • CMC carboxymethyl cellulose
  • the mass content of the thickener in the negative electrode active layer may be set to 0.5% to 5%. In the exemplary embodiment, it may be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc., which are typical but non-limiting contents, or a range between any two content values.
  • each sodium battery cell contains a separator
  • the separator is arranged between the positive electrode and the negative electrode as described above to separate the positive electrode and the negative electrode.
  • the separator can prevent electrons in the battery from passing freely to prevent contact short circuit between the electrodes, but can allow sodium ions in the electrolyte to pass freely between the positive electrode and the negative electrode.
  • the separator can be any known porous structure separator with electrochemical stability and mechanical stability.
  • the separator includes a single layer or multilayer film of at least one of glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP) and polyvinylidene fluoride (PVDF).
  • the solid electrolyte when each of the above sodium battery monomers contains a solid electrolyte, the solid electrolyte is arranged between the positive electrode and the negative electrode as described above to separate the positive electrode and the negative electrode.
  • the solid electrolyte may include at least one of a polymer solid electrolyte, an oxide electrolyte, a sulfide electrolyte, a borohydride electrolyte, a composite solid electrolyte, and the like.
  • the sodium battery monomer cells of the above-mentioned embodiments of the present application have been charged and discharged for 1000cls.
  • the DCR growth rate of the battery cell is less than 180%. Therefore, the DC internal resistance (DCR) of the sodium battery cell containing the positive electrode material composition of the above application embodiment is stable during the charge and discharge process, and the DCR growth rate is small.
  • the DCR detection method of the sodium battery cell is detected according to the method in the following embodiment.
  • the working voltage of the sodium battery monomer of the embodiment of the present application is 1.5-4.0V, that is, the sodium battery monomer of the embodiment of the present application can be discharged at 1.5-4.0V.
  • the energy density of the sodium battery monomer of the embodiment of the present application at 1.5-4.0V can reach 120-130Wh/K. Therefore, the sodium battery monomer of the embodiment of the present application also has a high energy density.
  • the DCR, energy density and other performance testing methods of the sodium battery single cell are tested according to the methods in the following embodiments.
  • the battery module refers to being assembled from the above-mentioned sodium battery monomers, that is, it can contain a plurality of the above-mentioned sodium battery monomers, and the specific number can be adjusted according to the application and capacity of the battery module.
  • FIG5 is a schematic diagram of a battery module 30 as an example.
  • a plurality of sodium battery cells 20 may be arranged in sequence along the length direction of the battery module 30. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 20 may be fixed by fasteners.
  • the battery module 30 may further include a housing having an accommodation space in which the plurality of sodium battery cells 20 are accommodated.
  • the battery pack refers to the assembly of the above sodium battery monomers, that is, it can contain multiple sodium battery monomers, and the multiple sodium battery monomers are assembled into the above battery module.
  • the specific number of battery monomers or battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.
  • FIG. 6 and FIG. 7 are schematic diagrams of a battery pack 40 as an example.
  • the battery pack 40 may include a battery box and a plurality of battery modules 30 disposed in the battery box.
  • the battery box includes an upper box body 41 and a lower box body 42, wherein the upper box body 41 is used to cover the lower box body 42 and form a closed space for accommodating the battery module 30.
  • the plurality of battery modules 30 may be arranged in the battery box in any manner.
  • the embodiments of the present application also provide an electric device.
  • the electric device of the embodiments of the present application includes a power supply unit or an energy storage unit, and of course may also include other auxiliary components or necessary components.
  • the power supply unit or energy storage unit contains the sodium battery of the above-mentioned embodiments of the present application.
  • it can be the above-mentioned sodium battery cell, battery module or battery pack.
  • the power supply unit or energy storage unit of the electric device of the embodiments of the present application has good cycle performance, high energy density, long service life, and the standby or battery life of the electric device of the embodiments of the present application is long.
  • the electric device may include but is not limited to a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc.
  • the electric toy may include a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc.
  • the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.
  • a battery cell, a battery module, or a battery pack in a battery may be selected according to its use requirements.
  • Fig. 8 is a schematic diagram of an electric device as an example.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.
  • a battery pack or a battery module may be used.
  • the electrical device when the electrical device contains an energy storage unit, the electrical device can be an energy storage device, and the energy storage device includes the energy storage unit, and of course can also include other auxiliary components or necessary components.
  • the energy storage unit contains the battery of the above text application embodiment.
  • the battery contained in the energy storage unit can be one or more. When there are multiple batteries, multiple batteries can form a battery module or battery pack. Since the energy storage device of the embodiment of the present application contains the battery of the above text application embodiment, the energy storage device has high energy density, good cycle performance, long service life, and further high energy density.
  • the positive electrode material composition includes two nickel-iron-manganese-based sodium positive electrode active materials, which are physically mixed in the proportions shown in Table 1 to form a mixture.
  • the method for preparing the positive electrode material composition comprises the following steps:
  • S2 The precursors of Chemical Formula I and Chemical Formula II are sintered and crushed in a muffle furnace to obtain nickel-iron-manganese-based sodium positive electrode active materials represented by Chemical Formula I and Chemical Formula II, respectively, and then dry-mixed in a ratio of 0.5:1 between Formula II and Formula I to form a mixture; wherein the sintering conditions are: temperature: 800°C; time: 8h; heating rate: 10°C/min; oxygen atmosphere.
  • Embodiments A2 to A7 of the present invention respectively provide a positive electrode material composition and a preparation method thereof.
  • the positive electrode material composition is different in that the physical mixing ratio of the two nickel-iron-manganese-based sodium positive electrode active materials is different, and the others are the same as the positive electrode material composition in Embodiment A1.
  • the molar ratio of Formula II to Formula I in Embodiment A2 is 0.6:1
  • the molar ratio of Formula II to Formula I in Embodiment A3 is 1.5:1
  • the molar ratio of Formula II to Formula I in Embodiment A4 is 3:1
  • the molar ratio of Formula II to Formula I in Embodiment A5 is 4:1
  • the molar ratio of Formula II to Formula I in Embodiment A6 is 5:1
  • the molar ratio of Formula II to Formula I in Embodiment A7 is 6:1.
  • the preparation methods of the positive electrode material compositions in Examples A2 to A7 are prepared by referring to the preparation method of the positive electrode material composition in Example A1.
  • the positive electrode material composition includes two nickel-iron-manganese-based sodium positive electrode active materials, which are physically mixed in the proportions shown in Table 1 to form a mixture.
  • the method for preparing the positive electrode material composition comprises the following steps:
  • S2 The precursors of Chemical Formula I and Chemical Formula II are sintered in a muffle furnace and crushed to obtain nickel-iron-manganese-based sodium positive electrode active materials represented by Chemical Formula I and Chemical Formula II, respectively, and then dry-mixed in a ratio of 6.3:1 between Formula II and Formula I to form a mixture; wherein the sintering conditions are: temperature: 800°C; time: 8h; heating rate: 10°C/min; oxygen atmosphere.
  • the positive electrode material composition comprises two nickel-iron-manganese-based sodium positive electrode active materials, and the two nickel-iron-manganese-based sodium positive electrode active materials are prepared in the proportions shown in Table 1 below. A mixture formed by physical mixing.
  • the method for preparing the positive electrode material composition comprises the following steps:
  • S2 The precursors of Chemical Formula I and Chemical Formula II are sintered and crushed in a muffle furnace to obtain nickel-iron-manganese-based sodium positive electrode active materials represented by Chemical Formula I and Chemical Formula II, respectively, and then dry-mixed in a ratio of 0.5:1 between Formula II and Formula I to form a mixture; wherein the sintering conditions are: temperature: 800°C; time: 8h; heating rate: 10°C/min; oxygen atmosphere.
  • the positive electrode material composition includes two nickel-iron-manganese-based sodium positive electrode active materials, which are physically mixed in the proportions shown in Table 1 to form a mixture.
  • the method for preparing the positive electrode material composition comprises the following steps:
  • S2 The precursors of Chemical Formula I and Chemical Formula II are sintered in a muffle furnace and crushed to obtain nickel-iron-manganese-based sodium positive electrode active materials represented by Chemical Formula I and Chemical Formula II, respectively, and then dry-mixed in a ratio of 3:1 between Formula II and Formula I to form a mixture; wherein the sintering conditions are: temperature: 800°C; time: 8h; heating rate: 10°C/min; oxygen atmosphere.
  • the positive electrode material composition includes two nickel-iron-manganese-based sodium positive electrode active materials, which are physically mixed in the proportions shown in Table 1 to form a mixture.
  • the method for preparing the positive electrode material composition comprises the following steps:
  • S2 The precursors of Chemical Formula I and Chemical Formula II are sintered and crushed in a muffle furnace to obtain nickel-iron-manganese-based sodium positive electrode active materials represented by Chemical Formula I and Chemical Formula II, respectively, and then dry-mixed in a ratio of 3:1 between the molar ratio of Formula II and Formula I to form a mixture; wherein the sintering conditions are: temperature: 800°C; time: 8h; heating rate: 10°C/min; oxygen atmosphere.
  • This comparative example provides a positive electrode material composition and a preparation method thereof.
  • the positive electrode material composition comprises two nickel-iron-manganese-based sodium positive electrode active materials, which are physically mixed in the proportions shown in Table 1 to form a mixture.
  • the method for preparing the positive electrode material composition comprises the following steps:
  • NiO, ZnO, Mn 2 O 3 , Fe 2 O 3 , and CaO are ball-milled at a speed of 800 rpm for 5 hours, and then sodium carbonate is added in proportion for mixing to obtain a precursor of chemical formula I;
  • NiO, ZnO , Mn 2 O 3 , Fe 2 O 3 , CuO , and Al 2 O 3 are ball-milled at a speed of 800 rpm for 5 hours, and then sodium carbonate is added in proportion for mixing to obtain a precursor of chemical formula II according to the molar ratio of metal elements contained in chemical formula II: Na 0.91 Ni 0.26 Fe 0.24 Mn 0.37 Cu 0.12 Al 0.01 O 2;
  • S2 The precursors of Chemical Formula I and Chemical Formula II are sintered in a muffle furnace and crushed to obtain nickel-iron-manganese-based sodium positive electrode active materials represented by Chemical Formula I and Chemical Formula II, respectively, and then dry-mixed in a ratio of 1:10 between Formula II and Formula I to form a mixture; wherein the sintering conditions are: temperature: 800°C; time: 8h; heating rate: 10°C/min; oxygen atmosphere.
  • Embodiments B1 to B11 provide a sodium ion battery cell, respectively.
  • Each sodium ion battery cell includes an electrode assembly formed by a positive electrode sheet, a separator and a negative electrode sheet, and also includes an electrolyte.
  • the sodium ion battery monomers in Examples B1 to B11 are assembled as follows:
  • Positive electrode sheet Sodium ion positive electrode active material, conductive agent carbon nanotubes, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) are fully stirred and mixed in an appropriate amount of solvent NMP in a weight ratio of 95:0.5:2:2.5 to form a uniform positive electrode slurry; the positive electrode slurry is evenly coated on the surface of a 13 ⁇ m positive electrode collector aluminum foil, and after drying and cold pressing, the positive electrode sheets contained in Examples B1 to B10 are obtained; wherein the sodium ion positive electrode active material is the positive electrode material composition in the above-mentioned Examples A1 to A10 respectively; the positive electrode sheet contained in Example B1 is the positive electrode sheet contained in Example B1 using the positive electrode material composition in Example A11 as the positive electrode material, and the carbon nanotubes contained therein are replaced with carbon fibers, and the content thereof is controlled to be 0.8%. As shown in Table 2, the total content of the conductive agent in the positive electrode sheet contained in Example B1 is the same as the total content
  • Negative electrode sheet Add hard carbon, conductive agent SP, and CMC binder into deionized water in a weight ratio of 8:1:1 and stir and mix thoroughly to form a uniform negative electrode slurry; evenly coat the negative electrode slurry on the surface of a 6 ⁇ m copper foil, and obtain a negative electrode sheet after drying and cold pressing.
  • Electrolyte In an environment with a water content of less than 10 ppm, non-aqueous organic solvents ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain an electrolyte solvent, and then sodium hexafluorophosphate and the mixed solvent are mixed to prepare an electrolyte with a sodium salt concentration of 1 mol/L.
  • Isolation membrane Porous polyethylene (PE) membrane is used as the isolation membrane.
  • Example B1 is the positive electrode material composition in the above-mentioned Example A1
  • the sodium ion positive electrode active material contained in Example B2 is the positive electrode material composition in the above-mentioned Example A2.
  • the sodium ion positive electrode active material contained in Example B11 is the positive electrode material composition in the above-mentioned Example A11.
  • This comparative example B1 provides a sodium ion battery cell, each of which includes an electrode assembly formed by a positive electrode sheet, a separator and a negative electrode sheet, and also includes an electrolyte.
  • the sodium ion battery monomers in Comparative Example B1 are prepared with reference to the sodium ion battery monomers in Example B1. The differences are:
  • the sodium ion positive electrode active material contained in the positive electrode sheet of the sodium ion battery cell is respectively the positive electrode material composition in Comparative Example A1.
  • Element content detection method of nickel-iron-manganese-based sodium positive electrode active material Agilent ICP-OES730 was used to obtain Inductively coupled plasma emission spectroscopy (ICP), and then the ICP results are used to calculate the content of each metal element in the positive electrode material compositions provided in Examples A1 to A11 and Comparative Example A1, and the molar content of each metal element in the positive electrode material composition per unit mole is converted according to the molar mixing ratio of each nickel-iron-manganese-based sodium positive electrode active material in each composition.
  • ICP Inductively coupled plasma emission spectroscopy
  • Charge/discharge gram capacity detection method According to the charge/discharge gram capacity detection method of the positive electrode material composition in the above application example, the charge/discharge gram capacity of the positive electrode material composition provided in Examples A1 to A11 and Comparative Example A1 was measured respectively.
  • CW detection method The positive electrodes in each battery cell in Examples B1 to B17 and Comparative Examples B1 to B2 were punched into 1540.25 mm 2 pole pieces, and the weight of the pure active material layer was obtained by weighing and subtracting the weight of the aluminum foil, which was recorded as weight of the active material layer/1540.25 mm 2 .
  • the specific compaction density of the positive electrode sheet can refer to the first discharge specific capacity and first charge and discharge efficiency test method of lithium manganese oxide, a positive electrode material of lithium-ion batteries, for details, see GB/T 39864-2021 standard or GB/T 42161-2022. For details, please refer to the test steps of the following parameters:
  • a punching machine was used to punch out positive electrode sheets with a diameter of 14 mm from the positive electrodes of each battery cell in Examples B1 to B17 and Comparative Examples B1 to B2, and an electronic balance and a tabletop digital thickness gauge were used to measure the mass m c and thickness d c of the positive electrode sheets.
  • a punching machine was used to punch out a sufficient number of aluminum foil substrates with a diameter of 14 mm, and an electronic balance and a tabletop digital thickness gauge were used to measure the mass m Al and thickness d Al of the aluminum foil substrates.
  • the compaction density of each positive electrode sheet was calculated according to the following formula:
  • ⁇ c is the compacted density of the positive electrode sheet, in grams per cubic centimeter (g/cm 3 );
  • m c is the mass of the positive electrode, in grams (g);
  • mAl is the mass of the aluminum foil substrate, in grams (g);
  • d c is the thickness of the positive electrode sheet, in micrometers ( ⁇ m);
  • dAl is the thickness of the aluminum foil substrate, in micrometers ( ⁇ m).
  • Cycle retention rate (%) At 25°C, each battery cell in Example B1 to Example B17 and Comparative Example B1 to Comparative Example B2 is charged to 3.85V at a constant current of 0.33C, then charged to a current of 0.05C at a constant voltage of 3.85V, and then discharged to 1.5V at a constant current of 1C. This is one charge and discharge cycle.
  • the capacity retention rate of the battery after 1000 cycles is calculated with the capacity of the first discharge as 100%.
  • Capacity retention rate of the battery after 1000 cycles (%) discharge capacity of the 1000th cycle/capacity of the first discharge ⁇ 100%.
  • DCR growth rate (%): At 25°C, charge the battery cell at a constant current rate of 0.33C to a voltage of 4.1V, let it stand for 5 minutes, discharge it at 1C to 1.5V, let it stand for 15 minutes, charge it at a constant current rate of 0.33C to a voltage of 4.1V, discharge it at 0.33C to 50% SOC, let it stand for 30 minutes, record the voltage, and pulse discharge it at 4C for 30 seconds, and record the voltage after the pulse discharge.
  • DCR Resistance value
  • the cell was charged at 0.33C constant current to a voltage of 4.1V, allowed to stand for 5 minutes, discharged at 1C to 1.5V, allowed to stand for 15 minutes, charged at 0.33C constant current again to a voltage of 4.1V, and discharged at 0.33C to 50% SOC. After standing for 30 minutes, the voltage was recorded, and the cell was pulse discharged at 4C for 30 seconds, and the voltage after pulse discharge was recorded.
  • DCR growth rate cell DCR after 1000 cycles / initial cell DCR.
  • Examples A1 to A7 with Examples A8 to A9, and of Examples B1 to B7 with Examples B8 to B9 shows that adjusting the copper and zinc elements in the positive electrode material composition at the same time can significantly affect the stability of the DCR of the corresponding sodium ion battery monomer cell.
  • the copper element and the zinc element in the positive electrode material composition are adjusted to Example A8 and Example A9, respectively, the DCR growth rate of the corresponding sodium ion battery monomer cell of the battery cell is higher than the DCR growth rate of the sodium ion battery monomer cell in Example B1 to Example B7. Therefore, in the positive electrode material composition, the total molar content of the copper element and the molar content of the zinc element can improve the DCR growth of the battery cell.
  • Example A4 Example A10 to Example A11 and Example B4, Example B10 to Example B11 that when the zinc element contained in the positive electrode material composition of the embodiment of the present application is replaced with magnesium element and titanium element, the DCR of the sodium ion battery monomer cell containing the corresponding positive electrode material composition can be kept relatively stable during the charge and discharge process.
  • the DCR growth rate of the sodium ion battery monomer in Example B10 to Example B11 is less than 180%.
  • the positive electrode material composition containing the embodiment of the present application has a relatively high gram capacity, and the corresponding sodium ion battery monomer cell also has good energy density and cycle performance.
  • the positive electrode sheet containing the positive electrode material composition of the embodiment of the present application can achieve a higher compaction density. Therefore, the positive electrode material composition of the embodiment of the present application can make the electrode sheet have a relatively high electrode sheet compaction density.

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Abstract

一种正极材料组合物及其制备方法、正极，钠电池和用电装置。正极材料组合物包括至少两种镍铁锰基钠电正极活性材料，各镍铁锰基钠电正极活性材料物理混合，镍铁锰基钠电正极活性材料的混合物还含有Cu元素和Q元素。正极含有该正极材料组合物，钠电池含有该正极。用电装置含有该钠电池。该正极材料组合物能够提高电池电性在充放电过程中的直流内阻稳定性。

Description

正极材料组合物及其制备方法、正极、钠电池和用电装置
本申请要求于2023年11月30日在中国专利局提交的、申请号为202311641701.9、发明名称为“正极材料组合物及其制备方法、正极、钠电池和用电装置”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。
技术领域
本申请属于钠电池技术领域，具体涉及一种正极材料组合物及其制备方法、正极、钠电池和用电装置。
背景技术
钠离子电池具有原料储量丰富，价格低廉，化学性能相对稳定，安全性好的优势，有望替代锂离子电池进入市场。随着新能源汽车不断发展和清洁能源占比不断增大，对离子电池的能量转换效率、能量密度及循环稳定性等提出了更高的要求。
其中，电池电芯的阻抗及阻抗的稳定性是影响电芯能量转换效率的重要因素之一。但是当前电池电芯如钠电池的阻抗稳定性的还有待进一步改善，以更好的满足当前市场对电池应用的需要。
发明内容
鉴于上述问题，本申请提供一种正极材料组合物及其制备方法和含有该正极材料组合物的正极和含有该正极的钠电池，以解决现有电池电芯的阻抗稳定性不理想的技术问题。
第一方面，本申请实施例提供了一种正极材料组合物。本申请实施例正极材料组合物包括至少两种镍铁锰基钠电正极活性材料，各所述镍铁锰基钠电正极活性材料物理混合，所述镍铁锰基钠电正极活性材料的混合物还含有Cu元素和Q元素，在单位摩尔量的所述正极材料组合物中，Na的总摩尔含量为0.78～1moL；
Ni的总摩尔含量为0.12～0.38moL；
Mn的总摩尔含量为0.18～0.48moL；
Fe的总摩尔含量为0.18～0.35moL；
Q的总摩尔含量为0.01～0.12moL；
Cu的总摩尔含量为0.01～0.14moL；
所述Q包括Zn、Mg、Ti中的至少一种元素。
本申请实施例正极材料组合物采用两种以上的镍铁锰基钠电正极活性材料形成物理混合物，并对混合物中所含Na、Ni、Mn、Fe、Cu、Q元素等金属元素含量控制在上述范围，使得含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)相对稳定，能够明显降低电池电芯在充放电过程中的DCR增长率。在此基础上，还能够改善电池电芯的能量密度和循环性能。
一些实施例中，在单位摩尔量的所述正极材料组合物中，所述Na、Ni、Mn、Fe、Cu和Y中的至少一元素的摩尔含量为：
所述Na的总摩尔含量为0.8～1moL；
所述Ni的总摩尔含量为0.15～0.35moL；
所述Mn的总摩尔含量为0.20～0.45moL；
所述Fe的总摩尔含量为0.20～0.33moL；
所述Q的总摩尔含量为0.01～0.06moL；
所述Cu的总摩尔含量为0.02～0.09moL。
通过将Na、Ni、Mn、Fe、Cu元素和Q所示金属元素中至少一种元素的总摩尔含量选控在上范围，能够进一步调节各镍铁锰基钠电正极活性材料所含过渡金属层中金属元素的无序排列，调节过渡金属层与钠层的间距，以进一步提高含本申请实施例正极 材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性能，特别是上述范围含量的Cu元素和Q所示金属元素能够提高对电池电芯DCR稳定性的增效作用，进一步提高电池电芯的DCR稳定性。同时进一步提高各镍铁锰基钠电正极活性材料的循环性能和克容量的发挥。
一些实施例中，至少一种所述镍铁锰基钠电正极活性材料还含有活性或/和惰性的掺杂金属元素，在单位摩尔量的所述正极材料组合物中，所述掺杂金属元素的总摩尔含量大于0，小于或等于为0.13moL，可选为大于0，小于或等于为0.1moL。该含量范围的掺杂金属元素能够参与镍铁锰基钠电正极活性材料所含过渡金属层中金属元素之间的无序排列和能够调节过渡金属层与钠层的间距，也能改善各镍铁锰基钠电正极活性材料的相关电化学性能，进一步提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性能，以缓解电池电芯在充放电过程中DCR的增长。同时也能够改善镍铁锰基钠电正极活性材料的结构稳定性和/或克容量的发挥。
示范例中，所述掺杂金属元素包括V、Ca、Cr、Al、Sc、Sn、Sb、Zr、Nb、Ru、Ir中的至少一种。该些种类的掺杂金属元素对含掺杂金属元素的镍铁锰基钠电正极活性材料所含过渡金属层进行掺杂，调节过渡金属层中金属元素的无序排列和能够调节过渡金属层与钠层的间距，可以进一步提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性能，以缓解电池电芯在充放电过程中DCR的增长和改善镍铁锰基钠电正极活性材料的结构稳定性和/或克容量的发挥。
一些实施例中，在单位摩尔量的所述正极材料组合物中，所述Na元素摩尔含量与其他金属元素的总摩尔含量比为(0.81～0.89)：1，可选为(0.82～0.89)：1。将Na元素摩尔总含量与其他金属元素的总摩尔含量比控制在该范围，能够进一步调节钠离子的含量，提高该镍铁锰基钠电正极活性材料可嵌脱的钠离子含量，从而提高该正极材料组合物的可逆容量；而且能够提高镍铁锰基钠电正极活性材料的结构稳定性，以提高其循环性能。
一些实施例中，所述Cu元素和Q元素分布在不同的镍铁锰基钠电正极活性材料中。通过含Cu元素的镍铁锰基钠电正极活性材料和含有Q元素的镍铁锰基钠电正极活性材料的复配形成混合物，能够平衡本申请实施例正极材料组合物的克容量和循环性能，同时还能够进一步提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性能，以缓解电池电芯在充放电过程中DCR的增长。
实施例中，含所述Q元素的所述镍铁锰基钠电正极活性材料包括如下(1)至(4)中的至少一者：
(1)Dv50粒径为3～8μm，可选为4～6.5μm；
(2)Dv90粒径为8～16μm，可选为10～14μm；
(3)在3吨压力下的压实密度高于3.1g/cm3，可选为3.1～3.4g/cm3；
(4)比表面积为0.4～1.0m2/g，可选为0.6～0.9m2/g。
实施例中，含所述Cu元素的所述镍铁锰基钠电正极活性材料包括如下(1)至(4)中的至少一者：
(1)Dv50粒径为5～11μm，可选为6.5～10μm；
(2)Dv90粒径为13～19μm，可选为14.5～18μm；
(3)在3吨压力下的压实密度为3.0～3.3g/cm3，可选为3.0～3.25g/cm3；
(4)比表面积为0.4～0.7m2/g，可选为0.5～0.6m2/g。
含Q元素的镍铁锰基钠电正极活性材料和含Cu元素的镍铁锰基钠电正极活性材料具有上述范围特征，能够提高本申请实施例正极材料组合物与电解液接触界面的稳定性等性能和提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性能。同时也可以改善本申请实施例正极材料组合物的克容量和循环性能。
一些实施例中，各所述镍铁锰基钠电正极活性材料独立的包括如下(1)至(2)中的至少一者：
(1)晶体结构包括O3相层状金属氧化物，且所述O3相层状金属氧化物占所述层状氧化物总重量的95％以上；和/或
(2)包括单晶，所述单晶的形貌呈块状。
选用该单晶的O3相镍铁锰基钠电正极活性材料具有相对高的结构稳定性，提高电池电芯的循环性能。
一些实施例中，所述正极材料组合物在1.5～4.2V和0.1C下的放电克容量为115～128mAh/g，可选为120～128mAh/g。
第二方面，本申请实施例提供了正极材料组合物的制备方法。本申请实施例正极材料组合物的制备方法包括如下步骤：
按照单位摩尔量的上文所述正极材料组合物所含所述Na、Ni、Mn、Fe、Q和Cu的摩尔含量比例，将至少两种镍铁锰基钠电正极活性材料进行物理混合，形成正极材料组合物。
本申请实施例正极材料组合物制备方法通过将至少两种镍铁锰基钠电正极活性材料按照Na、Ni、Mn、Fe、Cu、Q元素含量范围的比例进行混合，使得含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)增长率小，也使得本申请实施例正极材料组合物具有高的克容量和循环性能。
第三方面，本申请实施例提供了一种正极。本申请实施例正极包括正极活性物质层，所述正极活性物质层包括本申请实施例正极材料组合物或由本申请实施例正极材料组合物制备方法制备的正极材料组合物。
由于本申请实施例正极的正极活性物质层中含有上文本申请实施例正极材料组合物。因此，含本申请实施例正极的电池电芯在充放电过程中的直流内阻(DCR)增长率小。同时，电池电芯的能量密度高，而且循环性能好
一些实施例中，所述正极活性物质层在集流体单面上的含量为260～350mg/1540.25mm2，可选为280～320mg/1540.25mm2。
一些实施例中，所述正极的极片压实密度为2.6～3.4g/cm3，可选为2.8～3.2g/cm3。
一些实施例中，所述正极活性物质层的孔隙率为40％～70％，可选为50％～65％。
一些实施例中，所述正极为极片，且由所述极片的一个表面至相对的另一表面的厚度与集流体厚度比为7～15：1，可选为8～14：1。
一些实施例中，所述正极为极片，所述极片的膜片电阻为0.5～5mΩ，可选为0.5～3mΩ。
本申请实施例正极具有上述范围特征时，极片与电解液接触界面稳定性，使得含本申请实施例正极的电池电芯在充放电过程中的直流内阻(DCR)相对稳定，电池电芯的能量密度高，循环性能好
一些实施例中，所述正极活性物质层所含的导电剂包括线性导电剂。
实施例中，所述线性导电剂包括如下(1)至(5)中的至少一者：
(1)在所述正极活性物质层中的质量含量为比为0.1％～2.5％，可选为0.3～0.7％；
(2)长径比为40～3000：1，可选为50～2500：1；
(3)的长度为0.5～5μm，可选为0.5～2μm；
(4)的直径为2～10nm，可选为3～7nm；
(5)包括碳纳米管、碳纤维、导电氧化物纳米线中的至少一种。
在正极活性物质层中添加线性导电剂，且将线性导电剂的含量控制在该范围和对线性导电剂的种类、长径比、长度和直径等选控在上述范围，使得该线性导电剂能够在正极活性物质层中形成丰富的导电网络结构，且线性导电剂还可以缠绕在呈扁平状单晶颗粒表面。颗粒导电剂能够有效分散在该正极材料组合物的间隙中。这样，线性导电剂有效提高了正极活性物质层的导电性，能够明显降低正极的内阻，而且也有利于提高电池电性在充放电过程中的DCR稳定性。
第四方面，本申请实施例提供了一种钠电池。本申请实施例钠电池包括上文本申请实施例正极。本申请实施例钠电池单体所含电极组件与电解液接触界面稳定性，在 充放电过程中的直流内阻(DCR)稳定性好。在此基础上，电池电芯还具有能量密度高，循环性能好等电化学性能。
一些实施例中，所述钠电池为钠电池单体，所述钠电池单体包括如下(1)至(3)中的至少一者：
(1)工作电压为1.5～4.0V；和/或
(2)在1.5～4.0V下的能量密度120～130Wh/Kg；
(3)经1000cls后钠电池单体电芯的直流电阻增长率低于180％。
第五方面，本申请实施例提供了一种用电装置，本申请实施例包括本申请实施例钠电池。
本申请实施例用电装置待机或续航时间长，使用寿命长。
上述说明仅是本申请技术方案的概述，为了能够更清楚了解本申请的技术手段，而可依照说明书的内容予以实施，并且为了让本申请的上述和其它目的、特征和优点能够更明显易懂，以下特举本申请的具体实施方式。
附图说明
通过阅读对下文优选实施方式的详细描述，各种其他的优点和益处对于本领域普通技术人员将变得清楚明了。附图仅用于示出优选实施方式的目的，而并不认为是对本申请的限制。而且在全部附图中，用相同的附图标号表示相同的部件。在附图中：
图1为本申请一些实施例正极的一种结构示意图；
图2为本申请一些实施例正极的另一种结构示意图；
图3为本申请实施例钠电池单体的一实施方式的结构示意图；
图4为图3所示钠电池单体的分解示意图；
图5为本申请实施例电池模块的一实施方式结构示意图；
图6为本申请实施例电池包的一实施方式结构示意图；
图7为图6所示电池包的分解结构示意图；
图8为包含本申请实施例电池作为电源的用电装置的一实施方式的示意图。
具体实施方式中的附图标号如下：
10-正极，11集流体，12-正极活性物质层；
20-电池单体，21-壳体，22-电极组件，23-盖板；
30-电池模块；
40-电池包，41-上箱体，42-下箱体。
具体实施方式
下面将结合附图对本申请技术方案的实施例进行详细的描述。以下实施例仅用于更加清楚地说明本申请的技术方案，因此只作为示例，而不能以此来限制本申请的保护范围。
除非另有定义，本文所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同；本文中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本申请；本申请的说明书和权利要求书及上述附图说明中的术语“包括”和“具有”以及它们的任何变形，意图在于覆盖不排他的包含。
在本申请实施例的描述中，技术术语“第一”“第二”等仅用于区别不同对象，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量、特定顺序或主次关系。在本申请实施例的描述中，“多个”的含义是两个以上，除非另有明确具体的限定。
在本文中提及“实施例”意味着，结合实施例描述的特定特征、结构或特性可以包含在本申请的至少一个实施例中。在说明书中的各个位置出现该短语并不一定均是指相同的实施例，也不是与其它实施例互斥的独立的或备选的实施例。本领域技术人员显式地和隐式地理解的是，本文所描述的实施例可以与其它实施例相结合。
在本申请实施例的描述中，术语“和/或”仅仅是一种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，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
在本申请实施例的描述中，术语“多个”指的是两个以上(包括两个)，同理，“多组”指的是两组以上(包括两组)，“多片”指的是两片以上(包括两片)。
在本申请实施例的描述中，技术术语“中心”“纵向”“横向”“长度”“宽度”“厚度”“上”“下”“前”“后”“左”“右”“竖直”“水平”“顶”“底”“内”“外”“顺时针”“逆时针”“轴向”“径向”“周向”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请实施例和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请实施例的限制。
在本申请实施例的描述中，除非另有明确的规定和限定，技术术语“安装”“相连”“连接”“固定”等术语应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或成一体；也可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通或两个元件的相互作用关系。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本申请实施例中的具体含义。
钠离子电池(sodium-ion battery，简称SIBs)由于原料储量丰富，价格低廉成为储能系统理想的候选者。而且在新能源汽车市场中也存在巨大的应用空间。随着储能系统和新能源汽车的快速发展，市场对电池包括钠离子电池的能量转换效率、能量密度及循环稳定性等性能的要求也越来越高。
其中，电芯的阻抗和阻抗稳定性是影响电芯能量转换效率的重要因素之一。当前降低电芯的阻抗或提高阻抗的稳定性一般主要包括优化极片设计、改进电解液浸润性以及采用先进的制程工艺等方法。虽然这些能够在一定程度上的改善电芯的阻抗和提高阻抗的稳定性等，但是这些方法对电芯的阻抗和阻抗稳定性的改善效果不是特别理想，同时还会导致电芯能量密度或循环性能等的化学性能降低或成本的升高。
对于钠离子电池而言，钠离子电池正极材料能够提供活性钠离子，是钠离子电池的重要组成部分。在钠离子电池正极材料中，钠电层状氧化物由于其较高的克容量以及近似于锂离子电池正极材料的结构而备受关注。
基于钠电层状氧化物正极材料的结构，当前认为钠电层状氧化物正极材料对钠电池电芯的能量密度和循环性能有重要关联。因此，本行业当前也是对钠电层状氧化物正极材料的进行晶体稳定性和掺杂等调节改善钠电层状氧化物正极材料的克容量和结构稳定性等电化学性能，以达到改善钠电电芯的能量密度和循环性能等目的。
在研究改善电池如钠电池的能量转换效率过程中，提出一种钠电层状氧化物正极材料的组合物，通过将至少两类钠电层状氧化物正极材料进行物理混合复配，形成钠电层状氧化物正极材料的组合物，并对组合物中的过渡金属元素的种类和含量进行调控，将其作为电池电芯后，发现其能够明显的改善电芯的阻抗，如能够明显的提高电池电芯在充放电过程中的直流内阻(DCR)稳定性，降低了电池电芯在充放电过程中DCR的升高速率，从而能够提高电池电芯的能量转换效率。在此基础上，还可以改善电池电芯的能量密度和循环性能等电化学性能。基于上述研究，本申请实施例提出了如下技术方案。
正极材料组合物
第一方面，本申请实施例提供了一种正极材料组合物。一些实施例中，本申请实施例正极材料组合物包括至少两种镍铁锰基钠电正极活性材料，各镍铁锰基钠电正极活性材料物理混合，由该镍铁锰基钠电正极活性材料形成的混合物还含有Cu元素和Q元素。且在单位摩尔量的正极材料组合物中，Na、Ni、Mn、Fe、Cu、Q元素含量分别如下：
Na的总摩尔含量为0.78～1moL；
Ni的总摩尔含量为0.12～0.38moL；
Mn的总摩尔含量为0.18～0.48moL；
Fe的总摩尔含量为0.18～0.35moL；
Q的总摩尔含量为0.01～0.12moL；
Cu的总摩尔含量为0.01～0.14moL；
其中，Q包括Zn、Mg、Ti中的至少一种元素。
在本申请实施例正极材料组合物中，镍铁锰基钠电正极活性材料是指含镍元素、铁元素和锰元素的钠电层状氧化物正极材料。该钠电层状氧化物正极材料是指由交替排列且含包括Ni、Mn、Fe等过渡金属层(TMO6)和钠层(NaO6)构成的正极材料。物理混合是指将至少两种上述镍铁锰基钠电正极活性材料物理互混，非晶相掺杂，如互混后不经如烧结处理等处理。
本申请实施例正极材料组合物通过将两种以上的镍铁锰基钠电正极活性材料进行物理混合，并对混合物中所含Na、Ni、Mn、Fe、Cu、Q元素等金属元素含量控制在上述范围，使得含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)相对稳定，能够明显降低电池电芯在充放电过程中的DCR增长率。其中，上述范围含量的Cu元素和Q所示金属元素能够在极材料组合物中起到对电池电芯DCR稳定性的增效作用，能够明显的提高电池电芯的DCR稳定性。
在此基础上，由于至少一种镍铁锰基钠电正极活性材料含有上述摩尔含量范围的Cu元素、Q元素，Cu元素、Q元素参与了镍铁锰基钠电正极活性材料所含过渡金属层中金属元素之间的无序排列和能够调节过渡金属层与钠层的间距，提高了该镍铁锰基钠电正极活性材料在脱嵌钠过程中的结构稳定性和/或克容量的充分发挥，提高了本申请实施例正极材料组合物的克容量和循环性能，从而对应提高了电池电芯的能量密度和循环性能。
一些实施例中，在单位摩尔量的正极材料组合物中，Na元素的总摩尔含量可以为0.78～1moL，可选为0.8～1moL，进一步可以为0.89～0.91moL，示范例中，Na元素的总摩尔含量可以为0.78moL、0.8moL、0.82moL、0.85moL、0.88moL、0.89moL、0.9moL、0.91moL、0.92moL、0.95moL、0.98moL、1.0moL等典型但非限制性的化学计量含量或者任意两化学计量含量值之间的范围。该含量范围的Na元素提高了正极材料组合物的可逆容量。
一些实施例中，在单位摩尔量的正极材料组合物中，Ni元素的总摩尔含量可以为0.12～0.38moL，可选为0.15～0.35moL，进一步可以为0.2～0.3moL，示范例中，Ni元素的总摩尔含量可以为0.12moL、0.15moL、0.18moL、0.20moL、0.22moL、0.25moL、0.28moL、0.30moL、0.32moL、0.35moL、0.38moL等典型但非限制性的化学计量含量或者任意两化学计量含量值之间的范围。
一些实施例中，在单位摩尔量的正极材料组合物中，Fe元素的总摩尔含量可以为0.18～0.35moL，可选为0.20～0.33moL，进一步可以为0.24～0.28moL，示范例中，Fe元素的总摩尔含量可以为0.18moL、0.20moL、0.22moL、0.24moL、0.25moL、0.28moL、0.30moL、0.32moL、0.33moL等典型但非限制性的化学计量含量或者任意两化学计量含量值之间的范围。
上述含量范围的Ni元素、Fe元素中的至少一元素能够与各镍铁锰基钠电正极活性材料所含的包括上述含量的Cu元素或Q元素中的至少一种、Mn元素等元素一起参与各镍铁锰基钠电正极活性材料所含过渡金属层中金属元素之间的无序排列和能够调节过渡金属层与钠层的间距等，从而改善各镍铁锰基钠电正极活性材料的相关电化学性能，从而进一步提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性能，进一步缓解电池电芯在充放电过程中DCR的增长。在此基础上，还能够提高该镍铁锰基钠电正极活性材料克容量以提高本申请实施例正极材料组合物的克容量。进一步可以改善镍铁锰基钠电正极活性材料在脱嵌钠过程中的结构稳定性，提高本申请实施例正极材料组合物的循环性能。
一些实施例中，在单位摩尔量的正极材料组合物中，Mn元素的总摩尔含量可以为 0.18～0.48moL，可选为0.20～0.45moL，进一步可以为0.39～0.41moL，示范例中，Mn元素的总摩尔含量可以为0.18moL、0.20moL、0.22moL、0.25moL、0.28moL、0.30moL、0.32moL、0.35moL、0.38moL、0.39moL、0.40moL、0.41moL、0.42moL、0.45moL、0.48moL等典型但非限制性的化学计量含量或者任意两化学计量含量值之间的范围。该含量范围的Mn元素能够与各镍铁锰基钠电正极活性材料所含的包括上述含量的Cu元素或Q元素中的至少一种、Ni元素、Fe元素等元素一起参与各镍铁锰基钠电正极活性材料的相关电化学性能，进一步提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性能，进一步缓解电池电芯在充放电过程中DCR的增长。在此基础上，提高了各镍铁锰基钠电正极活性材料在脱嵌钠过程中的结构稳定性，提高各镍铁锰基钠电正极活性材的循环性能。
一些实施例中，在单位摩尔量的正极材料组合物中，Q元素的总摩尔含量可以为0.01～0.12moL，可选为0.01～0.1moL，进一步可以为0.01～0.06moL，示范例中，Q元素的总摩尔含量可以为0.01moL、0.02moL、0.03moL、0.04moL、0.05moL、0.06moL、0.07moL、0.08moL、0.09moL、0.10moL、0.11moL、0.12moL等典型但非限制性的化学计量含量或者任意两化学计量含量值之间的范围。当镍铁锰基钠电正极活性材料含有该含量范围的Q元素时，该Q元素也能够参与含Q元素的镍铁锰基钠电正极活性材料的过渡金属层中金属元素之间的无序排列，调节过渡金属层与钠层的间距，从而改善各镍铁锰基钠电正极活性材料的相关电化学性能，进一步提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性能，以缓解电池电芯在充放电过程中DCR的增长。而且，上述含量范围的Q所示金属元素还能够与上文范围含量的Cu元素在组合物中进一步起到对电池电芯DCR稳定性的增效作用，进一步提高电池电芯的DCR稳定性。
同时，也能够进一步提高含Q元素的镍铁锰基钠电正极活性材料在脱嵌钠过程中克容量的充分发挥，提高了本申请实施例正极材料组合物的克容量；还能够降低含Q元素的镍铁锰基钠电正极活性材料中Fe元素发生的迁移，改善各自镍铁锰基钠电正极活性材料在脱嵌钠过程中的结构稳定性，提高，提高本申请实施例正极材料组合物的循环性能。
一些实施例中，在单位摩尔量的正极材料组合物中，Cu元素的总摩尔含量可以为0.01～0.14moL，可选为0.01～0.12moL，进一步可以为0.02～0.09moL、0.02～0.07moL，示范例中，Cu元素的总摩尔含量可以为0.01moL、0.02moL、0.03moL、0.04moL、0.05moL、0.06moL、0.07moL、0.08moL、0.09moL、0.10moL、0.11moL、0.12moL、0.13moL、0.14moL等典型但非限制性的化学计量含量或者任意两化学计量含量值之间的范围。当镍铁锰基钠电正极活性材料含有该含量范围的Cu元素时，该Cu元素也能够参与含Cu元素的镍铁锰基钠电正极活性材料的过渡金属层中金属元素之间的无序排列，调节过渡金属层与钠层的间距，也能改善各镍铁锰基钠电正极活性材料的相关电化学性能，从而进一步提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性能，以缓解电池电芯在充放电过程中DCR的增长。同样，上述含量范围的Cu元素还能够与上文范围含量的Q所示金属元素在组合物中进一步起到对电池电芯DCR稳定性的增效作用，进一步提高电池电芯的DCR稳定性。同时，还能进一步提高含Cu元素的镍铁锰基钠电正极活性材料在脱嵌钠过程中的结构稳定性。
一些实施例中，本申请实施例正极材料组合物所含的至少一种镍铁锰基钠电正极活性材料还含有活性或/和惰性的掺杂金属元素，在单位摩尔量的正极材料组合物中，掺杂金属元素的总摩尔含量大于0，小于或等于为0.13moL；可选为大于0，小于或等于为0.1moL；示范例中，掺杂金属元素的总摩尔含量可以为0.01moL、0.02moL、0.03moL、0.04moL、0.05moL、0.06moL、0.07moL、0.08moL、0.09moL、0.10moL、0.11moL、0.12moL、0.13moL等典型但非限制性的化学计量含量或者任意两化学计量含量值之间的范围。该含量范围的掺杂金属元素能够参与含掺杂金属元素的镍铁锰基钠电正极活性材料所含过渡金属层中金属元素之间的无序排列和能够调节过渡金属层与钠层的间距， 与上述Ni、Mn、Fe或进一步Cu元素或Q元素中的至少一种一起，也能改善各镍铁锰基钠电正极活性材料的相关电化学性能，从而进一步提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性能，以缓解电池电芯在充放电过程中DCR的增长。同时，根据R所示掺杂金属元素的种类，还可以进一步提高含掺杂金属元素的镍铁锰基钠电正极活性材料的结构稳定性和/或克容量的发挥。当为活性的掺杂金属元素时，可以降低Ni元素的含量，从而降低含掺杂金属元素的镍铁锰基钠电正极活性材料的经济成本。
实施例中，上述掺杂金属元素可以包括V、Cr、Ca、Al、Sc、Sn、Sb、Zr、Nb、Ru、Ir中的至少一种。其中，活性的掺杂金属元素可以包括V、Cr、Sc、Sn、Sb、Nb、Ca等中的至少一种金属元素，惰性的掺杂金属元素可以Al、Zr、Ir、Ru等中的至少一种金属元素。该些种类的掺杂金属元素对含掺杂金属元素的镍铁锰基钠电正极活性材料所含过渡金属层进行掺杂，调节过渡金属层中金属元素的无序排列和能够调节过渡金属层与钠层的间距，可以进一步提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性能，以缓解电池电芯在充放电过程中DCR的增长。另外，根据掺杂金属元素的种类，如惰性的掺杂金属元素还能够降低对铁点位的敏感性，且能够协助Mn元素进一步提高含掺杂金属元素的镍铁锰基钠电正极活性材料在脱嵌钠过程中的结构稳定性，进一步提高该含掺杂金属元素的镍铁锰基钠电正极活性材料循环性能。如活性的掺杂金属元素还能够与Fe元素还能够进一步提升含掺杂金属元素的镍铁锰基钠电正极活性材料的克容量，从而可以对应提高电池单体的能量密度。
基于上述各实施例中单位摩尔量的本申请实施例正极材料组合物所含Cu和Q中的至少一元素和Na、Ni、Mn、Fe或进一步所含掺杂金属元素的摩尔含量范围，一些实施例中，在单位摩尔量的正极材料组合物中，Na、Ni、Mn、Fe、Cu和Q、掺杂金属元素的总摩尔含量可以如下：
Na的总摩尔含量为0.8～1moL；
Ni的总摩尔含量为0.15～0.35moL；
Mn的总摩尔含量为0.20～0.45moL；
Fe的总摩尔含量为0.20～0.33moL；
Q的总摩尔含量为0.01～0.06moL；
Cu的总摩尔含量为0.02～0.09moL；
掺杂金属元素的总摩尔含量为0～0.13moL，可选为0～0.1moL。
通过将Na、Ni、Mn、Fe、Cu元素和Q所示金属元素或进一步掺杂金属元素的总摩尔含量选控在该范围，能够进一步调节各镍铁锰基钠电正极活性材料所含过渡金属层中金属元素的无序排列和过渡金属层与钠层的间距，以进一步提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性能。同时进一步提高各镍铁锰基钠电正极活性材料的循环性能和克容量的发挥。
一些实施例中，在单位摩尔量的正极材料组合物中，上述各实施例中本申请实施例正极材料组合物中Na元素摩尔总含量与其他金属元素的总摩尔含量比为(0.81～0.89)：1，可选为(0.82～0.89)：1，示范例中，可以是0.81：1、0.82：1、0.83：1、0.84：1、0.85：1、0.86：1、0.87：1、0.88：1、0.89：1等典型但非限制性的摩尔比或者任意两摩尔比值之间的范围。将Na元素摩尔总含量与其他金属元素的总摩尔含量比控制在该范围，能够进一步调节钠离子的含量，提高该镍铁锰基钠电正极活性材料可嵌脱的钠离子含量，从而提高本申请实施例正极材料组合物的可逆容量；而且，该含量范围的钠离子能够提高各镍铁锰基钠电正极活性材料的O3晶相含量，使得各镍铁锰基钠电正极活性材料主要呈现O3晶，从而提高镍铁锰基钠电正极活性材料的结构稳定性，以提高其循环性能。
另外，上述各实施例中本申请实施例正极材料组合物所含的镍铁锰基钠电正极活性材料由于为钠电层状氧化物正极材料。因此，各镍铁锰基钠电正极活性材料还含有氧原子。该氧原子的含量可以是钠电层状氧化物正极材料常规的含量范围。上述各实 施例中正极材料组合物及其所含的镍铁锰基钠电正极活性材料中的元素种类及含量均可以采用下文的Agilent ICP-OES730得到电感耦合等离子体发射光谱(ICP)进行检测。
另外，上述各实施例中本申请实施例正极材料组合物所含的至少两种镍铁锰基钠电正极活性材料的物理混合比例，可以按照上文各元素在单位摩尔量的本申请实施例正极材料组合物中的总摩尔量含量范围内进行调节。
一些实施例中，上述各实施例中本申请实施例正极材料组合物所含的Cu元素和Q元素是分布在不同的镍铁锰基钠电正极活性材料中。这样，含Cu元素的镍铁锰基钠电正极活性材料在充放电过程中具有相对高的结构稳定性，从而可以提高本申请实施例正极材料组合物的循环性能；含有Q元素的镍铁锰基钠电正极活性材料具有相对高的克容量，从而可以提高本申请实施例正极材料组合物的克容量。因此，含Cu元素的镍铁锰基钠电正极活性材料和含有Q元素的镍铁锰基钠电正极活性材料的复配形成混合物，能够平衡本申请实施例正极材料组合物的克容量和循环性能，从而对应平衡电池电性的能量密度和循环性能。同时还能够进一步提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性能，以缓解电池电芯在充放电过程中DCR的增长。
当然，上述Cu元素和Q元素也可以是分布在同一镍铁锰基钠电正极活性材料中。
一些实施例中，当Cu元素和Q元素是分布在不同的镍铁锰基钠电正极活性材料中时，经检测，实施例中，含上述Q元素的镍铁锰基钠电正极活性材料的粉体Dv50粒径可以为3～8μm，可选为4～6.5μm，示范例中，Dv50粒径可以3μm、4μm、4.5μm、5μm、5.5μm、6μm、6.5μm、7μm、7.5μm、8μm等典型但非限制性的粒径或者任意两粒径值之间的范围。该含上述Q元素的镍铁锰基钠电正极活性材料的Dv90粒径可以为8～16μm，可选为10～14μm，示范例中，Dv90粒径可以8μm、9μm、10μm、11μm、12μm、13μm、14μm、15μm、16μm等典型但非限制性的粒径或者任意两粒径值之间的范围。
实施例中，含上述Cu元素的镍铁锰基钠电正极活性材料的粉体Dv50粒径可以为5～11μm，可选为6.5～10μm，示范例中，Dv50粒径可以5μm、5.5μm、6μm、6.5μm、7μm、7.5μm、8μm、8.5μm、9μm、9.5μm、10μm、10.5μm、11μm等典型但非限制性的粒径或者任意两粒径值之间的范围。含上述Cu元素的镍铁锰基钠电正极活性材料的粉体Dv90粒径可以为13～19μm，可选为14.5～18μm，示范例中，Dv90粒径可以13μm、14μm、14.5μm、15μm、16μm、17μm、18μm、19μm等典型但非限制性的粒径或者任意两粒径值之间的范围。
其中，该Dv50粒径是指含上述Q元素或Cu元素的镍铁锰基钠电正极活性材料粉体中的累计粒度分布百分数达到50％时所对应的粒径。该Dv90粒径是指含上述Q元素或Cu元素的镍铁锰基钠电正极活性材料粉体中的累计粒度分布百分数达到90％时所对应的粒径。Dv50和Dv90可以按照GB/T16418中的方法步骤对各镍铁锰基钠电正极活性材料的Dv50和Dv90粒径进行分别测定。
上述范围的Dv50粒径、Dv90粒径能够提高含上述Q元素的镍铁锰基钠电正极活性材料与含上述Cu元素的镍铁锰基钠电正极活性材料等镍铁锰基钠电正极活性材料之间的复配作用，进一步提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性能，以缓解电池电芯在充放电过程中DCR的增长。同时具有合适的比表面积，改善正极片与电解液接触界面的稳定性。
一些实施例中，当Cu元素和Q元素是分布在不同的镍铁锰基钠电正极活性材料中时，实施例中，含上述Q元素的镍铁锰基钠电正极活性材料颗粒的比表面(BET)为0.4～1.0m2/g，可选为0.6～0.9m2/g，示范例中，可以0.4m2/g、0.5m2/g、0.6m2/g、0.7m2/g、0.8m2/g、0.9m2/g、1.0m2/g等典型但非限制性的比表面或者任意两比表面值之间的范围。
实施例中，含上述Cu元素的镍铁锰基钠电正极活性材料颗粒的比表面(BET)为0.4～0.7m2/g，可选为0.5～0.6m2/g，示范例中，可以0.4m2/g、0.5m2/g、0.55m2/g、 0.6m2/g、0.7m2/g等典型但非限制性的比表面或者任意两比表面值之间的范围。
该范围含Q元素的镍铁锰基钠电正极活性材料和含Cu元素的镍铁锰基钠电正极活性材料粉体的比表面积，能够提高该含Q元素的镍铁锰基钠电正极活性材料和含Cu元素的镍铁锰基钠电正极活性材料与电解液接触界面的稳定性等性能，进一步提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性能。
一些实施例中，当Cu元素和Q元素是分布在不同的镍铁锰基钠电正极活性材料中时，实施例中，含上述Q元素的镍铁锰基钠电正极活性材料粉体在3吨压力下的压实密度高于3.1g/cm3，可选为3.1～3.4g/cm3，示范例中，在3吨压力下的该压实密度为可以3.1g/cm3、3.2g/cm3、3.3g/cm3、3.4g/cm3等典型但非限制性的压实密度或者任意两压实密度值之间的范围。
实施例中，含上述Cu元素的镍铁锰基钠电正极活性材料粉体的在3吨压力下的压实密度可以为3.0～3.3g/cm3，可选为3.0～3.25g/cm3，示范例中，在3吨压力下的该压实密度为可以3g/cm3、3.1g/cm3、3.15g/cm3、3.2g/cm3、3.25g/cm3、3.3g/cm3等典型但非限制性的压实密度或者任意两压实密度值之间的范围。
该范围的含Q元素的镍铁锰基钠电正极活性材料和含Cu元素的镍铁锰基钠电正极活性材料粉体的比表面积，能够提高该含Q元素的镍铁锰基钠电正极活性材料和含Cu元素的镍铁锰基钠电正极活性材料与电解液接触界面的稳定性等性能，进一步提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性能。同时可以进一步提高含Q元素的镍铁锰基钠电正极活性材料和含Cu元素的镍铁锰基钠电正极活性材料的电池的克容量。
其中，上述各实施例中正极材料组合物及其所含的各镍铁锰基钠电正极活性材料粉体压实密度(compacted density)可以按照下述检测方法检测：
参照GB/T24533-2019标准测试方法检测，具体可参考如下测试步骤：
(1)用干净的软布(纸巾)擦拭压实密度仪的上下垫片、顶柱和金属圆柱套筒，必要时，用软布蘸无水乙醇擦拭风干；
(2)将垫片、顶柱、金属圆柱套筒、垫盘按照测试时的顺序放好后放置于数显测厚仪上，按归零键；
(3)取出顶柱和上垫片，称量1g上述实施例A1至实施例A12和对比例A1至对比例A2中所含的镍铁锰基钠电正极活性材料样品于套筒内，精确到0.0001g，记下重量为m；
(4)再将垫片和顶柱分别从孔中缓缓滑下，连同垫盘一起安装在压实密度仪上，拧紧压力控制旋钮；
(5)摇动压杠，同时观察压实密度仪上数显压力表上的数值，达到规定值2200Ib后启动秒表；30s后松开压力控制旋钮，撤除压力，垫盘下降至一定高度，再拧紧压力控制旋钮；
(6)连同垫盘一起取出顶柱、套筒和底片，放置于数显测厚仪上，10s内读取数显测厚仪上的数值，记为H；
r＝10m/(S×H)；
再根据r＝10m/(S×H)以上公式计算试样的粉末压实密度r。
其中，mm为样品重量，单位为克(g)；HH为样品压实后的厚度，单位为毫米(mm)；SS为顶柱的横截面积，单位为平方厘米(cm2)。
一些实施例中，上述各实施例中本申请实施例正极材料组合物所含的至少两种镍铁锰基钠电正极活性材料可以按照含Cu元素的镍铁锰基钠电正极活性材料与含Q元素的镍铁锰基钠电正极活性材料的摩尔比为0.5～28:1，可选为0.5～18:1的比例进行物理混合。示范例，可以是0.5：1、1：1、3：1、5：1、8：1、10：1、13：1、15：1、18：1、20：1、23：1、25：1、28：1等典型但非限制性的摩尔比或者任意两摩尔比之间的范围。实施例中，当Cu元素和Q元素是分布在不同的镍铁锰基钠电正极活性材 料中时，含Cu元素的镍铁锰基钠电正极活性材料总摩尔与含Q元素的镍铁锰基钠电正极活性材料的总摩尔比在上述物理混合摩尔比例范围。
通过将至少两种镍铁锰基钠电正极活性材料的物理混合摩尔比例控制在上述范围，能够充分发挥各镍铁锰基钠电正极活性材料之间的复配作用，提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的DCR稳定性能。同时可以进一步平衡本申请实施例正极材料组合物的电池的克容量和循环性能，从而提高对应电池电芯的能量密度和循环性能。
在一些实施例中，上述各实施例中本申请实施例正极材料组合物所含的镍铁锰基钠电正极活性材料选用O3相层状金属氧化物。其中，该O3相层状金属氧化物是指在其所含氧以ABCABC型方式堆垛的一类晶型结构的层状氧化物。实施例中，上述各实施例本申请实施例正极材料组合物所含的镍铁锰基钠电正极活性材料主要是O3晶相，且该O3晶相在各镍铁锰基钠电正极活性材料中重量含量可以是95％以上，进一步为98％以上，也可以达到100％。该O3晶相各镍铁锰基钠电正极活性材料中的重量占比越高越是期望的。各镍铁锰基钠电正极活性材料所含的O3晶相，使得各镍铁锰基钠电正极活性材料具有相对高的结构稳定性，如相对P2相层状金属氧化物而言具有相对高的结构稳定性，其循环性能更高，同时可以进一步提高含本申请实施例正极材料组合物的电池电芯在充放电过程中DCR的稳定性能。
一些实施例中，经电镜分析，上述各镍铁锰基钠电正极活性材料晶体包括单晶，该单晶呈块状。
基于上述各实施例中本申请实施例正极材料组合物所含镍铁锰基钠电正极活性材料中的元素种类、含量和混合比例以及具有的形貌、晶型、粒径等，经检测，一些实施例中，上述各实施例中本申请实施例正极材料组合物在1.5～4.2V和0.1C下的放电克容量可达115～128mAh/g，可选为120～128mAh/g。
上文本申请实施例正极材料组合物的充电克容量和放电克容量具体是将该本申请实施例正极材料组合物制备成正极，与负极分别组装成钠离子扣电池。并检测钠离子扣电池的克容量。
实施例中，用于检测本申请实施例正极材料组合物的充电克容量和放电克容量的上述钠离子扣电池按照如下方法组装：
正极片：将本申请实施例正极材料组合物为正极活性材料，与导电剂碳纳米管、导电剂炭黑、粘结剂聚偏氟乙烯(PVDF)按重量比95:0.5:2:2.5在适量的溶剂NMP中充分搅拌混合，形成均匀的正极浆料；将正极浆料均匀涂覆于13μm的正极集流体铝箔的表面上，经干燥、冷压后，得到正极片；
负极片：将硬碳、导电剂SP、CMC粘结剂按重量比8:1:1加入去离子水中充分搅拌混合，形成均匀的负极浆料；将负极浆料均匀涂覆于6μm的铜箔的表面上，经干燥、冷压后，得到负极片；
电解液：1M NaPF6/(EC/DEC，体积比1:1)；
隔膜：玻璃纤维；
钠离子扣电池组装：将上述正极极片、玻纤薄膜以及负极极片按顺序叠放，组装后形成扣式电池组件，将电极组件装入包装外壳中，加入1M NaPF6/(EC/DEC，体积比1:1)电解液，经封装、化成、静置等工艺后，得到钠离子扣电池。
正极材料组合物的制备方法
第二方面，本申请实施例提供了上文本申请实施例正极材料组合物制备方法。一些实施例中，本申请实施例正极材料组合物制备方法包括如下步骤：
S10：按照单位摩尔量的正极材料组合物所含Na、Ni、Mn、Fe、Q和Cu的摩尔含量比例，将至少两种镍铁锰基钠电正极活性材料进行物理混合，形成正极材料组合物。
在本申请实施例正极材料组合物制备方法的步骤S10中，镍铁锰基钠电正极活性材料为上文本申请实施例正极材料组合物中所含的镍铁锰基钠电正极活性材料，因此， 至少两种镍铁锰基钠电正极活性材料的物理混合也是指物理互混，非晶相掺杂。至少两种镍铁锰基钠电正极活性材料的混合比例需要满足在单位摩尔量的上文本申请实施例正极材料组合物中，Na、Ni、Mn、Fe、Cu、Q元素含量满足上文所述的范围，具体是：
Na的总摩尔含量为0.78～1moL，可选为0.8～1moL；
Ni的总摩尔含量为0.12～0.38moL，可选为0.15～0.35moL；
Mn的总摩尔含量为0.18～0.48moL，可选为0.20～0.45moL；
Fe的总摩尔含量为0.18～0.35moL，可选为0.20～0.33moL；
Q的总摩尔含量为0.01～0.12moL，可选为0.01～0.1moL；
Cu的总摩尔含量为0.01～0.14moL，可选为0.01～0.12moL。
这样，本申请实施例正极材料组合物制备方法通过将至少两种镍铁锰基钠电正极活性材料按照Na、Ni、Mn、Fe、Cu、Q元素含量范围的比例进行混合，使得含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)相对稳定，能够明显降低电池电芯在充放电过程中的DCR增长率。也使得本申请实施例正极材料组合物具有高的克容量和循环性能。
步骤S10的镍铁锰基钠电正极活性材料可以获取现有的镍铁锰基钠电正极活性材料，当然也可以根据本申请实施例正极材料组合物所含元素种类和含量进行改进的镍铁锰基钠电正极活性材料。
一些实施例中，步骤S10中镍铁锰基钠电正极活性材料可以按照如下方法制备：
S11：分别按照每一镍铁锰基钠电正极活性材料所含的元素比例，提供每一镍铁锰基钠电正极活性材料前驱体；
S12：将每一镍铁锰基钠电正极活性材料分别单独烧结处理，分别得到每一镍铁锰基钠电正极活性材料。
在本申请实施例正极材料组合物制备方法的步骤S11中，镍铁锰基钠电正极活性材料前驱体可以是含有钠源、镍源、锰源、铁源和进一步含铜源、Q所示金属元素源的按比例混合物，或进一步含有上文本申请实施例正极材料组合物中镍铁锰基钠电正极活性材料所含的掺杂金属源。
如实施例中，该镍铁锰基钠电正极活性材料前驱体可以采用固相法或沉淀法进行制备的镍铁锰基钠电正极活性材料前驱体。
当采用固相法制备镍铁锰基钠电正极活性材料前驱体时，实施例中，镍铁锰基钠电正极活性材料前驱体可以按照包括如下步骤的方法制备：
步骤S111：按照镍铁锰基钠电正极活性材料中元素计量比，将钠源、镍源、锰源、铁源以及铜源、Q所示金属元素源中的至少一种或进一步将掺杂元素源进行固相混合处理，得到镍铁锰基钠电正极活性材料前驱体。
当采用固相法制备镍铁锰基钠电正极活性材料前驱体时，固相混合处理是相对液相混合而言，一般是指在混合处理过程中不添加溶剂，如不添加水，也是在不含溶剂的条件下将步骤S111中各源固体进行干混合处理。
为了提高步骤S111中各源在固相混合处理过程中混合均匀，实施例中，可以先将步骤S111中的除钠源之外的其他源化合物先进行混合处理，再加入钠源进行再次混合处理。以提高各源的混合均匀性，并提高固相混合处理的安全性。
实施例中，该固相混合处理可以包覆但不限于球磨处理，只要是能够提高步骤S111中的各源化合物混合均匀的方法均在本申请实施例公开的范围。实施例中，当该混合处理为球磨处理时，该球磨的速率可以控制可以为300～1000转/分钟，可选为400～600转/分钟；球磨处理的时间可以为1h～6h，可选为2h～4h。通过对该球磨处理，能够提高各源的混合均匀性，从而能够最终提高步骤S12中镍铁锰基钠电正极活性材料的结构和电化学等性能的稳定性。
示范例中，该钠源可以钠盐，如可以包括碳酸钠、氢氧化钠等中的至少一种。
示范例中，该镍源可以是可溶或不溶的镍化合物，如可以是氧化镍(NiO)或镍盐等。 其中，镍盐可以包括硝酸镍、碳酸镍、氢氧化镍、硫酸镍等中的至少一种。
示范例中，该锰源可以是可溶或不溶的锰化合物，如可以是氧化锰(Mn2O3)或锰盐等。其中，锰盐可以包括硝酸锰、碳酸锰、氢氧化锰、硫酸锰等中的至少一种。
示范例中，该铁源可以是可溶或不溶的铁化合物，如可以是铁的氧化物(如Fe2O3)或铁盐等。其中，铁盐可以包括硝酸铁、碳酸铁、氢氧化铁、硫酸铁等中的至少一种。
示范例中，该铜源可以是可溶或不溶的铜化合物，如可以是铜的氧化物(如CuO)或铜盐等。其中，铜盐可以包括硝酸铜、碳酸铜、氢氧化铜、硫酸铜等中的至少一种。
示范例中，该Q所示金属元素源和掺杂金属元素源可以是可溶或不溶的Q所示金属元素和掺杂金属元素的化合物，如可以是Q所示金属元素和掺杂金属元素的氧化物或Q所示金属元素和掺杂金属元素的盐等。其中，Q所示金属元素和掺杂金属元素的盐可以包括Q所示金属元素和掺杂金属元素的硝酸盐、碳酸盐、氢氧化盐、硫酸盐等中的至少一种。
上述各钠源、镍源、锰源、铁源、铜源和Q所示金属元素和掺杂金属元素源的种类能够有效在混合处理过程中混合均匀，分别提高各镍铁锰基钠电正极活性材料前驱体分别生成镍铁锰基钠电正极活性材料的结构和化学稳定性。
当采用沉淀法制备镍铁锰基钠电正极活性材料前驱体可以按照包括如下步骤的方法制备：
步骤S113：按照镍铁锰基钠电正极活性材料中元素计量比，将可溶性镍源、可溶性锰源、可溶性铁源和以及铜源、Q所示金属元素源中的至少一种或进一步将掺杂元素源配制混合溶液，再加入沉淀剂、络合剂中的至少一种进行共沉淀处理，得到沉淀混合物；
步骤S114：将沉淀混合物与钠源进行混合处理，得到镍铁锰基钠电正极活性材料前驱体。
在步骤S113中，沉淀剂、络合剂中的至少一种应该是能够使得镍源、可溶性锰源、可溶性铁源、可溶性铜源和Q所示金属元素源以及掺杂元素源中的镍、锰、铁、铜和Q所示金属元素以及掺杂金属元素发生沉淀的化合物。步骤S113中的沉淀剂、络合剂可以相同，也可以不同。如实施例中，沉淀剂可以包括碱金属的氢氧化物、碳酸盐等中的至少一种。实施例中，该络合剂可以包括无机或有机络合剂，示范例中，该无机络合剂可以包括氨水、碳酸氢氨、硫酸铵、碳酸铵等中的至少一种；有机络合剂可以包括柠檬酸、酒石酸和乙二胺四二酸二钠、乙二胺四乙酸(EDTA)、氨基三乙酸(NTA)等中的至少一种。
该些种类的沉淀剂、络合剂能够有效将镍、锰、铁、铜和Q所示金属元素以及掺杂元素进行沉淀。
实施例中，该沉淀剂、络合剂中的至少一种应该是相对混合溶液所含的金属元素总量如总摩尔量是过量的，以确保相对混合溶液所含所有金属元素充分发生沉淀，以提高镍铁锰基钠电正极活性材料前驱体所含金属元素化学计量比的精度。
示范例中，该可溶性镍源可以包括乙酸镍、氯化镍、硝酸镍和硫酸镍等中的至少一种。
示范例中，该可溶性锰源可以包括锰的硝酸盐、硫酸锰、卤化物等中的至少一种。
示范例中，该可溶性铁源可以包括铁的硝酸盐、硫酸锰、卤化物等中的至少一种。
示范例中，该可溶性铜源可以包括铁的硝酸盐、硫酸锰、卤化物等中的至少一种。
示范例中，该可溶性Q所示金属元素以及掺杂金属元素源可以包括Q所示金属元素以及掺杂金属元素的硝酸盐、硫酸锰、卤化物等中的至少一种。
上述各可溶性镍源、可溶性锰源、可溶性铁源、可溶性铜源和可溶性Q所示金属元素以及掺杂元素源的种类均具有良好的溶解性，可以定量控制沉淀混合物中各金属元素的化学计量比。
步骤S114中的钠源与沉淀混合物之间的混合比例应该满足镍铁锰基钠电正极活性材料也即是钠电层状氧化物中钠离子的含量，具体如O3晶相层状氧化物中钠元素所要求的化学计量比。该混合处理可以是固相混合处理或将可溶性钠源溶解后与沉淀混合物混合，然后除去溶剂。
另外，步骤S114中的钠源可以钠盐，如可以包括碳酸钠、氢氧化钠等中的至少一种。
步骤S12：
步骤S12中对步骤S11中的至少两种镍铁锰基钠电正极活性材料前驱体分别烧结处理后，会分别生成各镍铁锰基钠电正极活性材料。在研究中发现，烧结处理条件对生成的镍铁锰基钠电正极活性材料的结构稳定性和电化学性能有一定的影响。一些实施例中，该烧结处理温度可以控制在700～980℃，可选为750～950℃，示范例中，可以为700℃、750℃、800℃、850℃、900℃、950℃、980℃等典型但非限制性的温度或者任意两温度值之间的范围。
在上述烧结温度下，烧结处理的时间可以为4h～20h，可选为6h～12h，示范例中，可以为4h、5h、8h、10h、12h、15h、18h、20h等典型但非限制性的小时或者任意两小时之间的范围。
通过对烧结处理的稳定和时间控制在上述范围，能够使得步骤S11中各镍铁锰基钠电正极活性材料前驱体反应分别生成各镍铁锰基钠电正极活性材料，并进一步提高各镍铁锰基钠电正极活性材料物理混合复配后的协效作用，进一步提高含本申请实施例正极材料组合物的电池电芯在充放电过程中的直流内阻(DCR)稳定性，同时还可以提高电芯的能量密度和循环性能等电化学性能。
实施例中，该烧结处理的温度可以2～20℃/min的升温速率升温至该烧结处理的温度。该升温速率进一步可以控制为5～15℃/min，示范例中，该升温速率可以为2℃/min、4℃/min、5℃/min、6℃/min、8℃/min、10℃/min、12℃/min、15℃/min、17℃/min、18℃/min、20℃/min等典型但非限制性的速率或者任意两速率值之间的范围。通过控制烧结处理的升温速率，如控制在该升温速率范围，能够提高各镍铁锰基钠电正极活性材料的晶体完善完整，如提高晶体形貌均一性。
另外，上述步骤S12中的烧结处理应该是理解的在有氧环境中进行，如实施例中，可以是空气中烧结处理或在含氧的保护气氛中进行，如可以是含氧的氮气或惰性其他中进行烧结处理。
正极
第三方面，本申请实施例提供了一种正极。一些实施例中，本申请实施例正极包括集流体和正极活性物质层。其中，正极活性物质层与集流体结合，且正极活性物质层含有上文本申请实施例正极材料组合物。
在本申请实施例正极中，集流体是指用于汇集电流的结构，用于传输电子。正极活性物质层是指含有正极活性材料的层结构，该正极活性材料在正极中参与电池化学反应的关键物质。其中，该正极活性材料包括上文本申请实施例正极材料组合物。正极活性物质层与集流体结合是指正极活性物质层至少结合在集流体的表面。另外，该正极可以是极片，该极片是指正极为片状形貌。当然也可以是根据需要设置成其他形貌。
由于本申请实施例正极的正极活性物质层中含有上文本申请实施例正极材料组合物。经检测，含本申请实施例正极的电池电芯在充放电过程中的直流内阻(DCR)相对稳定，能够明显降低电池电芯在充放电过程中的DCR增长率。同时，电池电芯的能量密度高，而且循环性能好。
实施例中，本申请实施例正极所含的集流体包括但不限于金属集流体、碳集流体、导电树脂集流体、金属与树脂的复合集流体等，更具体例如铝、铜、镍、钛、铁及它们各自的合金，不锈钢、碳纤维、碳纳米管(CNT)、石墨等。实施例中，该集流体还可以是致密的膜层，也可以是多孔结构的膜层。实施例中，该集流体可以但不限于铝箔或多孔铝箔等。
实施例中，本申请实施例正极所含的正极活性物质层与集流体结合可以是至少层叠在集流体的表面。当集流体的表层含有多孔结构或集流体本身为多孔结构时，该正极活性物质层可以是至少部分嵌入至集流体中。
一些实施例中，该正极活性物质层至少结合在集流体的表面可以是如图1所示的结构，正极活性物质层12层叠在集流体11的一个表面。当该集流体11的该表面具有多孔结构或集流体11整体为多孔结构时，该正极活性物质层12除了层叠结合在该集流体11的该表面上之外，还可以进一步延伸至该集流体11的多孔结构中。
另些实施例中，该正极活性物质层至少结合在集流体的表面可以是如图2所示的结构，集流体11具有相对设置的两个表面，该正极活性物质层12层叠在集流体11相对设置的两个表面上。当该集流体11的两表面中的至少一个表面具有多孔结构或集流体11整体为多孔结构时，该正极活性物质层12除了层叠结合在该集流体11的该两表面上之外，还可以进一步延伸至该集流体11的多孔结构中。
作为本申请的实施例，在上述正极活性物质层中，上文本申请实施例正极材料组合物总质量在正极活性物质层中的质量含量可以为90％～97％，可选地为94％～96.5％，示范例中，可以为90％、91％、92％、93％、94％、95％、96％、97％等典型但非限制性的含量或者任意两含量值之间的范围。该含量范围的正极材料组合物能够有效提高正极的能量密度，而且循环性好。
上文各申请实施例正极所含的正极活性物质层除了含有上文正极活性材料组分之外，一般还包括粘结剂、导电剂等组分。该粘结剂能够增强正极活性物质层自身和集流体之间的力学性能。导电剂能够有效提高正极的导电性，如降低正极的电阻。
实施例中，上述正极活性物质层所含粘结剂的质量含量可以为0.5％～5％，可选地为1％～3％，示范例中，可以为0.5％、0.8％、1％、1.3％、1.5％、1.8％、2％、2.3％、2.5％、2.8％、3％、3.5％、4％、4.5％、5％等典型但非限制性的含量或者任意两含量值之间的范围。
实施例中，该粘结剂可以包括油溶性粘结剂、水溶性粘结剂、乳液型粘结剂等中的一种或多种。示范例中，油溶性粘结剂可以包括聚偏氟乙烯、聚酰亚胺、聚四氟乙烯、聚丙烯酸丁酯、聚丙烯腈等中的一种或多种；示范例中，水溶性粘结剂可以包括羧甲基纤维素、羧甲基纤维素盐、聚丙烯酸、聚丙烯酸盐、聚乙烯醇、海藻酸钠、环糊精等中的一种或多种；示范例中，乳液型粘结剂包括丁苯橡胶、醋酸乙烯树脂、丙烯酸树脂、氯化橡胶中的一种或多种。
该范围含量和上述种类的粘结剂能够有效增强正极活性物质层的力学性能和与集流体之间的结合强度，能有效提高正极的循环性能。
实施例中，上述正极活性物质层所含导电剂的质量含量可以为0.5％～5％，可选地为1％～3％，示范例中，可以为0.5％、0.8％、1％、1.3％、1.5％、1.8％、2％、2.3％、2.5％、2.8％、3％、3.5％、4％、4.5％、5％等典型但非限制性的含量或者任意两含量值之间的范围。
实施例中，该导电剂可以包括颗粒导电剂、线性导电剂等中的至少一种。其中，该颗粒导电剂可以包括乙炔黑(SP)、导电炭黑(super-P)、科琴黑、石墨烯等中的一种或多种。线性导电剂可以包括碳纳米管、碳纤维、导电氧化物纳米线等中的一种或多种。该颗粒导电剂是相对线性导电剂而言，为非线性的颗粒形貌的导电剂。线性导电剂是指呈一维纤维形貌的导电剂。
该范围含量和上述种类的导电剂能够有效提高正极活性物质层的导电性。
实施例中，上文各实施例正极中的正极活性物质层所含的导电剂包括线性导电剂和颗粒导电剂。其中，该线性导电剂在该正极活性物质层中的质量含量为比为0.1％～2.5％，可选为0.3％～0.7％，示范例中，可以为0.1％、0.2％、0.3％、0.4％、0.5％、0.6％、0.7％、0.8％、1％、1.3％、1.5％、1.8％、2％、2.3％、2.5％等典型但非限制性的含量或者任意两含量值之间的范围。由于上文本申请实施例正极材料组合物所含镍铁锰基钠电正极活性材料的晶体包括单晶，且该单晶的形貌呈块状，因此，在该正极活性物质层中添加线性导电剂，且将线性导电剂的含量控制在该范围，使得该线性导电剂能够在正极活性物质层中形成丰富的导电网络结构，且线性导电剂还可以缠绕在呈块状单晶颗粒表面。颗粒导电剂能够有效分散在该正极材料组合物的间隙中。这样，线性导电剂在正极活性物质层中构建了长程导电网络结构，颗粒导电剂构成了短程导电结构，因此，线性导电剂和颗粒导电剂在该正极活性物质层中起到的导电增效作用，有效提高了正极活性物质层的导电性，能够明显降低正极的内阻，而且也有利于提高电池电性在充放电过程中的DCR稳定性。
实施例中，上述线性导电剂的长径比可以选控为40～3000：1，可选为50～2500：1，示范例中，可以40：1、50：1、100：1、500：1、1000：1、1500：1、2000：1、2500：1、3000：1等典型但非限制性的长径比或者任意两长径比值之间的范围。该长径比是指上述线性导电剂的长度与直径的比值。
在进一步实施例中，上述线性导电剂的长度可以选控为0.5～5μm，可选为0.5～2μm，示范例中，可以0.5μm、1μm、1.5μm、2μm、3μm、3.5μm、4μm、4.5μm、5μm等典型但非限制性的长度或者任意两长度值之间的范围。
在进一步实施例中，上述线性导电剂的直径可以选控为2～10nm，可选为3～7nm，示范例中，可以2nm、3nm、4nm、5nm、6nm、7nm、8nm、9nm、10nm等典型但非限制性的直径或者任意两直径值之间的范围。
通过对上述线性导电剂的长径比选控在上述范围，或进一步将上述线性导电剂的长度和直径选控在上述范围，能够使得线性导电剂在正极活性物质层中构建更丰富的长程导电网络结构，进一步增强线性导电剂和颗粒导电剂的导电增效作用，以进一步提高正极活性物质层的导电性。
实施例中，上文各实施例正极中的正极活性物质层除了含有正极活性材料、粘结剂和导电剂等组分之外，还可以含有其他添加剂。实施例中，该添加剂可以包括但不限于补钠添加剂等功能组分。
一些实施例中，上文各实施例中正极活性物质层在集流体单面上的含量也即是涂布重量(CW)为260～350mg/1540.25mm2，可选为280～320mg/1540.25mm2，示范例中，可以为260mg/1540.25mm2、270mg/1540.25mm2、280mg/1540.25mm2、290mg/1540.25mm2、300mg/1540.25mm2、310mg/1540.25mm2、320mg/1540.25mm2、330mg/1540.25mm2、340mg/1540.25mm2、350mg/1540.25mm2等典型但非限制性的含量或者任意两含量值之间的范围。该涂布重量是指单位面积的正极活性物质层的重量。该范围的涂布重量能够有效电池电芯在充放电过程中的直流内阻(DCR)相对稳定和提高电池电芯的能量密度。
一些实施例中，上文各实施例中正极活性物质层的压实密度也即是正极片的压实密度可以为2.6～3.4g/cm3，可选为2.8～3.2g/cm3，示范例中，可以为2.6g/cm3、2.7g/cm3、2.8g/cm3、2.9g/cm3、3.0g/cm3、3.1g/cm3、3.2g/cm3、3.3g/cm3、3.4g/cm3等典型但非限制性的压实密度或者任意两压实密度值之间的范围。该压实密度是指单位体积的正极活性物质层的重量。该范围的压实密度能够有效改善正极与电解液接触界面稳定性，提高电池电芯在充放电过程中的直流内阻(DCR)相对稳定和电池电芯的能量密度。
一些实施例中，上文各实施例中正极活性物质层的孔隙率可以为40％～70％，可选为50％～65％，示范例中，可以为40％、43％、45％、48％、50％、53％、55％、58％、60％、63％、65％、70％等典型但非限制性的孔隙率或者任意两孔隙率值之间的范围。该孔隙率是指单位体积的正极活性物质层中，所含孔隙的总体积与正极活性物质层单位体积百分比。该范围的孔隙率能够使得正极活性物质层具有上述的压实密度，进一步改善正极的电解液浸润性和改善与电解液接触界面稳定性，提高电池电芯在充放电过程中的直流内阻(DCR)相对稳定和电池电芯的能量密度。其中，上文各实施例中正极活性物质层(极片)的孔隙率可以按照下述方法检测：
通过气体置换法进行检测，具体参考GB/T24586-2009进行，极片孔隙率检测方法具体步骤：将实施例B1至实施例B17和对比例B1至对比例B2中各电池单体中正极分别浸渍于碳酸甲乙酯(EMC)中清洗，再采用GB/T24586-2009中规定的方法进行测试，利用气体置换法，结合阿基米德原理和波尔定律，精确测量被测材料的真实体积即为样品真体积，从而得到待测样品的孔隙率。其中，单个极片中的孔体积占极片总体积的百分比即为极片孔隙率，计算公式：孔隙率＝(V-V0)/V×100％，其中V0为真体积，V为表观体积。
一些实施例中，上文各实施例中正极为极片，上文各实施例中正极活性物质层的膜片电阻可以为0.5～5mΩ，可选为0.5～3mΩ，示范例中，可以为0.5mΩ、1mΩ、1.5mΩ、2mΩ、2.5mΩ、3mΩ、3.5mΩ、4mΩ、4.5mΩ、5mΩ等典型但非限制性的或者任意两膜 片电阻值之间的范围。该极片为上文所述的片状形貌，因此，其具有相对的两个表面。该膜片电阻是指片状形貌正极的一个表面至相对的另一表面之间的电阻值。该范围的膜片电阻能够有效提高电池的包括效率和寿命等性能。其中，上文极片的膜片电阻可以按照下述方法检测：
参考GB/T 30835-2014或者T/CASAS 019—2021方法进行检测；测试仪检定规程请参考JJG 508-2004方法进行检测。具体采用四探针法进行检测：将实施例B1至实施例B17和对比例B1至对比例B2中各电池单体中正极分别浸渍于碳酸甲乙酯(EMC)中清洗，采用填入GB/T 30835-2014或者T/CASAS 019—2021中规定的方法进行测试，将四只长1.5cm*宽1cm*厚2mm的铜板等距固定在一条线上，中间两块铜板的间距为L(1cm至2cm)，固定铜板的基材为绝缘材料，测试时将四只铜板下端面压在所测极片上，两端铜板接通直流电流I，在中间两只铜板测取电压V，读取三次I和V值，取I和V的平均值，V/I即为测试处的极片电阻。
一些实施例中，上文各实施例中正极为极片，由极片的一个表面至相对的另一表面的厚度与集流体厚度比为7～15：1，可选为8～14：1，示范例中，可以为7：1、8：1、9：1、10：1、11：1、12：1、13：1、14：1、15：1等典型但非限制性的比值或者任意两比值之间的范围。该厚度是指层结构一个表面至相对的另一表面垂直距离。当如图1所示的集流体一个表面设置正极活性物质层时，该极片的一个表面至相对的另一表面的厚度是指一层正极活性物质层的厚度加上集流体的厚度之和；当如图2所示的集流体两个表面均含有正极活性物质层时，该极片的一个表面至相对的另一表面的厚度是指两层正极活性物质层的厚度之和再加上集流体的厚度总和。
实施例中，该极片所含正极活性物质层的厚度可以控制为85～221μm，进一步可以117～182μm，示范例中，可以为85μm、90μm、100μm、110μm、117μm、120μm、130μm、140μm、150μm、160μm、170μm、180μm、182μm、190μm、200μm、210μm、220μm、221μm、等典型但非限制性的厚度或者任意两厚度值之间的范围。实施例中，该集流体的厚度可以但不限于13～15μm。
通过将极片的总厚度与集流体厚度控制在上述比值范围或具体厚度范围，能够有效改善极片所含正极活性物质层结构，如调控正极活性物质层的孔隙结构、膜片电阻和容量等性能，从而进一步改善正极的电解液浸润性和改善与电解液接触界面稳定性，提高电池电芯在充放电过程中的直流内阻(DCR)相对稳定和电池电芯的能量密度以及循环性能等电化学性能。
正极的制备方法：
本申请实施例还提供了上文实施例正极的制备方法。一些实施例中，上文实施例正极的制备方法包括如下步骤：
S20：将包括正极活性材料、粘结剂、导电剂等组分按比例于溶剂中进行混合处理，配制成正极浆料；
S30：将正极浆料在集流体上成膜处理形成正极活性物质层，得到正极。
步骤S20：
步骤S20中的正极活性材料包括上文本申请实施例正极材料组合物。
步骤S20中的正极活性材料、粘结剂、导电剂等组分可以按照上文正极的正极活性物质层所含相应组分含量比例进行混合处理。该溶剂可以选用适于配制正极浆料的有机溶剂或水等。
步骤S20中的混合处理可以按照常规电极浆料的配制方法进行混合处理，如包括但不限于搅拌处理，直至使得各组分分散均匀，形成稳定性的正极浆料。当然，该正极浆料的粘度等性能应该是符合成膜工艺的要求，以便在集流体上形成符合质量要求的正极活性物质层。
步骤S30：
基于步骤S20中配制的正极浆料组分，那么步骤S30中制备的正极活性物质层为上文本申请实施例正极所含的正极活性物质层。
步骤S30中将正极浆料在集流体上成膜处理可以按照常规正极活性物质层的方法进行成膜处理。如实施例中，可以是将该电极浆料在集流体上先形成湿膜；再进行干燥处理，使得溶剂挥发，从而使得湿膜干燥；然后对干燥的膜层进行辊压处理，形成正极活性物质层，从而得到正极。
当然也可以是对常规正极活性物质层制备方法进行改进后的方法制备正极活性物质层，还可以是采用新的方法制备正极活性物质层。只要是将步骤S20中的电极浆料在集流体上制备正极活性物质层均在本申请实施例说明书公开的范围。
另外，可以对S30中成膜处理条件控制和调节，如对步骤S20中配置的正极浆料在集流体上形成湿膜的条件、辊压处理的条件等控制和调节，能够控制和调节形成的正极活性物质层的相关性能，如将正极活性物质层在集流体单面上的含量控制和调节至如上文的250～330mg/1540.25mm2范围，压实密度控制和调节至如上文的2.6～3.2g/cm3范围，孔隙率控制和调节至如上文的35％～65％范围，极片的膜片电阻控制和调节至如上文的0.5～5mΩ范围等。
电池
第四方面，本申请实施例还提供了一种钠电池。
实施例中，本申请实施例钠电池可以包括钠电池单体、电池模块、电池包中的任一种。
钠电池单体：
钠电池单体也称钠电芯，是指包括电池外包装和封装于该电池外包装内的电极组件。电池单体所含电极组件的数量可以为一个或多个，可以根据实际需求来调节。
其中，钠电池单体的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等；也可以是软包，例如袋式软包。软包的材质可以是塑料，例如聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。外包装形状可以是圆柱形、方形或其他任意的形状。该外包装形状赋予了钠电池单体的形状，因此，钠电池单体的形状也可以是与外包装对应形状的圆柱形、方形或其他任意的形状。示范例中，该钠电池单体可以是如图3所示的方形结构的电池单体20。
在一些实施例中，如图4所示，电池单体20的外包装可包括壳体21和盖板23。壳体21可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体21具有与容纳腔连通的开口，盖板23用于盖设开口，以封闭容纳腔。一个或多种电极组件22封装于容纳腔内。
实施例中，该钠电池单体可以是含电解液的钠电池单体，也可以是含固态电解质的钠电池单体。
当为含电解液的钠电池单体时，钠电池单体所含的电极组件通常包括正极、负极和隔离膜。正极和负极交替层叠设置，隔离膜层叠设置在正极和负极之间以起到隔离作用，将正极和负极隔开。该正极、隔离膜层和负极可以通过叠片工艺形成叠层结构的电极组件，也可以通过卷绕工艺形成卷芯结构的电极组件。含隔离膜的电极组件置于外包装中，注入电解液并浸润该电极组件，经封装得到钠电池单体。
当为含固态电解质的钠电池单体时，钠电池单体所含的电极组件通常包括正极、负极和固态电解质。正极和负极交替层叠设置，固态电解质层叠设置在正极和负极之间以起到隔离作用，将正极和负极隔开。含固态电解质的电极组件置于外包装中，经封装得到钠电池单体。
在上述各钠电池单体中，电极组件所含的正极为上文本申请实施例正极，也即是在其正极活性物质层中含有上文本申请实施例正极材料组合物。这样，本申请实施例钠电池单体所含电极组件与电解液接触界面稳定性，在充放电过程中的直流内阻(DCR)相对稳定，在充放电过程中电池单体电芯的DCR增长率小。在此基础上，电池电芯还具有能量密度高，循环性能好等电化学性能。
在上述各钠电池单体中，电极组件所含的负极包括负极集流体，还可选地包括设置在负极集流体表面的负极活性物质层，负极活性物质层包含负极活性材料。实施例 中，负极集流体可以包括但不限于金属或复合集流体。例如，作为金属，可以采用钠、钠合金、铜、铜合金、镍、镍合金、钛、钛合金、银、银合金等。在采用钠或钠合金作为负极集流体的情况下，由于钠或钠合金自身也可以作为负极活性材料，因此负极极片可以不含负极活性物质层，钠或钠合金既是集流体也是负极活性材料。
复合集流体可以包括高分子材料与金属的复合材料，其中的高分子材料可以包括但不限于聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等，金属可以包括但不限于钠、铜、铜合金、镍、镍合金、钛、钛合金、银、银合金。复合集流体可以由高分子材料与金属相互掺混而得，也可以通过电镀、涂布或其他方式使覆于高分子材料的至少一侧。
当负极包括负极活性物质层时，负极活性物质层中的负极活性材料可以包括但不限于碳基材料、合金材料、钛基材料、钠金属中的任意一种或多种形成的混合或复合材料。其中碳基材料包括但不限于石墨、软碳、硬碳、碳微球、碳纤维中的一种或多种；合金材料包括但不限于钠锡合金、钠锗合金、钠锑合金中的一种或多种；钛基材料包括但不限于二氧化钛、钛酸盐、钛磷酸盐中的一种或多种。
负极活性材料在负极活性物质层中的质量含量可以为85％～98％，可选为95％～98％，示范例中，可以为85％、90％、91％、92％、93％、94％、95％、96％、97％、98％等典型但非限制性的含量或者任意两含量值之间的范围。
负极活性物质层还可以包括导电剂、粘结剂中的至少一种。导电剂用于在负极活性材料之间，以及活性材料与集流体之间收集电流，提高电子电导率，同时导电剂还可以促进电解液对负极极片的浸润。粘结剂则能够提高负极活性物质层中各物质之间，以及活性层与集流体之间的结合强度。
实施例中，导电剂在负极活性物质层的质量含量可以为0.5％～10％，示范例中，可以为0.5％、1％、2％、3％、4％、5％、6％、7％、8％、9％、10％等典型但非限制性的含量或者任意两含量值之间的范围，也可以根据需要设置为其他的含量。示范例中，导电剂包括乙炔黑(SP)、碳纳米管、导电炭黑(super-P)、科琴黑、碳纤维、石墨烯中的一种或多种。
实施例中，粘结剂在负极活性物质层中的质量含量可以为0.5％～10％，示范例中，可以为0.5％、1％、2％、3％、4％、5％、6％、7％、8％、9％、10％等典型但非限制性的含量或者任意两含量值之间的范围，也可以根据需要设置为其他的含量。示范例中，粘结剂包括但不限于聚偏二氟乙烯、聚偏氟乙烯-六氟丙烯共聚物、聚氧化乙烯、聚酰亚胺、聚四氟乙烯、聚丙烯酸丁酯、聚丙烯腈、羧甲基纤维素、羧甲基纤维素盐、聚丙烯酸、聚丙烯酸盐、聚乙烯醇、海藻酸钠、环糊精、丁苯橡胶、醋酸乙烯树脂、丙烯酸树脂、氯化橡胶中的一种或多种。
实施例中，负极活性物质层中还可选地包括增稠剂，如可以但不限于羧甲基纤维素(CMC)。增稠剂在负极活性层中的质量含量可以设置为0.5％～5％，示范例中，可以为0.5％、1％、1.5％、2％、2.5％、3％、3.5％、4％、4.5％、5％等典型但非限制性的含量或者任意两含量值之间的范围。
实施例中，当上述各钠电池单体含有隔离膜时，该隔离膜如上文所述的，是设置在正极和负极之间，将正极和负极分隔开。隔离膜可以让电池内的电子不能自由通过，防止电极之间接触短路，但是能够让电解质中的钠离子在正极与负极之间自由通过。该隔离膜可以选用任意公知的具有电化学稳定性和机械稳定性的多孔结构隔离膜，示范例中，隔离膜包括玻璃纤维、无纺布、聚乙烯(PE)、聚丙烯(PP)及聚偏二氟乙烯(PVDF)等中的至少一种的单层或多层薄膜。
实施例中，当上述各钠电池单体含有固态电解质时，该固态电解质如上文所述的，是设置在正极和负极之间，将正极和负极分隔开。固态电解质可以包括聚合物固体电解质、氧化物电解质、硫化物电解质、硼氢化物电解质、复合固态电解质等中的至少一种。
经检测，实施例中，上述各本申请实施例钠电池单体电芯经过1000cls充放电循 环后，电池单体电芯的DCR增长率低于180％。因此，含有上文本申请实施例正极材料组合物的钠电池单体在充放电过程中的直流内阻(DCR)稳定，该DCR增长率小。其中，该钠电池单体电芯的DCR检测方法按照下文实施例中的方法进行检测。
经进一步检测，如实施例中，本申请实施例钠电池单体的工作电压为1.5～4.0V，也即是本申请实施例钠电池单体可以在1.5～4.0V下进行放电。实施例中，本申请实施例钠电池单体在1.5～4.0V下的能量密度可以达到120～130Wh/K。因此，本申请实施例钠电池单体还具有高的能量密度。
其中，该钠电池单体电芯的DCR、能量密度等性能检测方法按照下文实施例中的方法进行检测。
电池模块：
当本申请实施例钠电池为电池模块时，该电池模块是指由上述钠电池单体组装而成，也即是可以含有多个上述钠电池单体，具体数量可根据电池模块的应用和容量来调节。
一些实施例中，图5是作为一个示例的电池模块30的示意图。如图5所示，在电池模块30中，多个钠电池单体20可以是沿电池模块30的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个电池单体20进行固定。
可选地，电池模块30还可以包括具有容纳空间的外壳，多个钠电池单体20容纳于该容纳空间。
电池包：
当本申请实施例钠电池为电池包时，电池包是指由上文钠电池单体组装而成，也即是可以含有多个钠电池单体，且该多个该钠电池单体组装成上文电池模块。电池包所含的电池单体或电池模块具体数量可根据电池包的应用和容量进行调节。
一些实施例中，图6和图7是作为一个示例的电池包40的示意图。在电池包40中可以包括电池箱和设置于电池箱中的多个电池模块30。电池箱包括上箱体41和下箱体42，上箱体41用于盖设下箱体42，并形成用于容纳电池模块30的封闭空间。多个电池模块30可以按照任意的方式排布于电池箱中。
用电装置
第五方面，本申请实施例还提供一种用电装置。本申请实施例用电装置包括电源单元或能量存储单元，当然还可以包括其他辅助部件或必要部件。其中，该电源单元或能量存储单元含有上文本申请实施例钠电池。如可以是上文钠电池单体、电池模块或电池包。由于本申请实施例用电装置含有上文本申请实施例钠电池，因此，本申请实施例用电装置的电源单元或能量存储单元循环性能好，能量密度高，使用寿命长，且本申请实施例用电装置的待机或续航时间长。
实施例中，该用电装置可以包括但不限于手机、平板、笔记本电脑、电动玩具、电动工具、电瓶车、电动汽车、轮船、航天器等等。其中，电动玩具可以包括固定式或移动式的电动玩具，例如，游戏机、电动汽车玩具、电动轮船玩具和电动飞机玩具等等，航天器可以包括飞机、火箭、航天飞机和宇宙飞船等等。作为用电装置，可以根据其使用需求来选择电池中的电池单体、电池模组或电池包。
图8是作为一个示例的用电装置的示意图。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。该为了满足该用电装置对高功率和高能量密度的需求，可以采用电池包或电池模块。
实施例中，当用电装置含能量存储单元时，该当用电装置可以为储能装置，储能装置包括能量存储单元，当然还可以包括其他辅助部件或必要部件。其中，该能量存储单元含有上文本申请实施例电池。该能量存储单元所含的电池可以是一个或多个。当为多个时，多个电池可以组成的电池模组或电池包。由于本申请实施例储能装置含有上文本申请实施例电池，因此，储能装置的能量密度高，循环性能好，使用寿命长，进一步的能量密度高。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
1.正极材料组合物及其制备方法实施例
实施例A1
本实施例提供一种正极材料组合物及其制备方法。该正极材料组合物包括两种镍铁锰基钠电正极活性材料，该两种镍铁锰基钠电正极活性材料按下表1中的比例进行物理混合形成的混合物。
该正极材料组合物制备方法包括如下步骤：
S1：按照化学式Ⅰ所示Na0.88Ni0.21Fe0.30Mn0.38Zn0.08Ca0.03O2所含金属元素摩尔比将NiO、ZnO、Mn2O3、Fe2O3、CaO于800转/分钟的转速下进行球磨处理5小时，再按比例加入碳酸钠进行混合处理，得到化学式Ⅰ的前驱体；按照化学式Ⅱ所示Na0.91Ni0.26Fe0.24Mn0.41Cu0.08Al0.01O2所含金属元素摩尔比将NiO、ZnO、Mn2O3、Fe2O3、CuO、Al2O3于800转/分钟的转速下进行球磨处理5小时，再按比例加入碳酸钠进行混合处理，得到化学式Ⅱ的前驱体；
S2：分别将化学式Ⅰ和化学式Ⅱ的前驱体于马弗炉中进行烧结处理，粉碎，分别得到化学式Ⅰ和化学式Ⅱ所示镍铁锰基钠电正极活性材料，然后按照式Ⅱ与式Ⅰ的摩尔比为0.5:1的比例干混形成混合物；其中，烧结处理的条件为：温度：800℃；时间：8h；升温速率：10℃/min；氧气气氛。
实施例A2至实施例A7
本实施例A2至实施例A7分别提供一种正极材料组合物及其制备方法。该正极材料组合物与实施例A1相比，不同在于该两种镍铁锰基钠电正极活性材料物理混合比例不同，其他与实施例A1中正极材料组合物相同。其中，实施例A2中式Ⅱ与式Ⅰ的摩尔比为0.6:1，实施例A3中式Ⅱ与式Ⅰ的摩尔比为1.5:1，实施例A4中式Ⅱ与式Ⅰ的摩尔比为3:1，实施例A5中式Ⅱ与式Ⅰ的摩尔比为4:1，实施例A6中式Ⅱ与式Ⅰ的摩尔比为5:1，实施例A7中式Ⅱ与式Ⅰ的摩尔比为6:1。
该实施例A2至实施例A7中正极材料组合物制备方法参照实施例A1中正极材料组合物的制备方法制备。
实施例A8
本实施例提供一种正极材料组合物及其制备方法。该正极材料组合物包括两种镍铁锰基钠电正极活性材料，该两种镍铁锰基钠电正极活性材料按下表1中的比例进行物理混合形成的混合物。
该正极材料组合物制备方法包括如下步骤：
S1：按照化学式Ⅰ所示Na0.88Ni0.21Fe0.25Mn0.38Zn0.13Ca0.03O2所含金属元素摩尔比将NiO、ZnO、Mn2O3、Fe2O3、CaO于800转/分钟的转速下进行球磨处理5小时，再按比例加入碳酸钠进行混合处理，得到化学式Ⅰ的前驱体；按照化学式Ⅱ所示Na0.91Ni0.26Fe0.24Mn0.35Cu0.14Al0.01O2所含金属元素摩尔比将NiO、ZnO、Mn2O3、Fe2O3、CuO、Al2O3于800转/分钟的转速下进行球磨处理5小时，再按比例加入碳酸钠进行混合处理，得到化学式Ⅱ的前驱体；
S2：分别将化学式Ⅰ和化学式Ⅱ的前驱体于马弗炉中进行烧结处理，粉碎，分别得到化学式Ⅰ和化学式Ⅱ所示镍铁锰基钠电正极活性材料，然后按照式Ⅱ与式Ⅰ的摩尔比为6.3:1的比例干混形成混合物；其中，烧结处理的条件为：温度：800℃；时间：8h；升温速率：10℃/min；氧气气氛。
实施例A9
本实施例提供一种正极材料组合物及其制备方法。该正极材料组合物包括两种镍铁锰基钠电正极活性材料，该两种镍铁锰基钠电正极活性材料按下表1中的比例进行 物理混合形成的混合物。
该正极材料组合物制备方法包括如下步骤：
S1：按照化学式Ⅰ所示Na0.88Ni0.15Fe0.30Mn0.38Zn0.14Ca0.03O2所含金属元素摩尔比将NiO、ZnO、Mn2O3、Fe2O3、CaO于800转/分钟的转速下进行球磨处理5小时，再按比例加入碳酸钠进行混合处理，得到化学式Ⅰ的前驱体；按照化学式Ⅱ所示Na0.91Ni0.26Fe0.24Mn0.46Cu0.04Al0.01O2所含金属元素摩尔比将NiO、ZnO、Mn2O3、Fe2O3、CuO、Al2O3于800转/分钟的转速下进行球磨处理5小时，再按比例加入碳酸钠进行混合处理，得到化学式Ⅱ的前驱体；
S2：分别将化学式Ⅰ和化学式Ⅱ的前驱体于马弗炉中进行烧结处理，粉碎，分别得到化学式Ⅰ和化学式Ⅱ所示镍铁锰基钠电正极活性材料，然后按照式Ⅱ与式Ⅰ的摩尔比为0.5:1的比例干混形成混合物；其中，烧结处理的条件为：温度：800℃；时间：8h；升温速率：10℃/min；氧气气氛。
实施例A10
本实施例提供一种正极材料组合物及其制备方法。该正极材料组合物包括两种镍铁锰基钠电正极活性材料，该两种镍铁锰基钠电正极活性材料按下表1中的比例进行物理混合形成的混合物。
该正极材料组合物制备方法包括如下步骤：
S1：按照化学式Ⅰ所示Na0.88Ni0.21Fe0.30Mn0.38Ti0.08Zr0.03O2所含金属元素摩尔比将NiO、TiO2、Mn2O3、Fe2O3、Ir2O3于800转/分钟的转速下进行球磨处理5小时，再按比例加入碳酸钠进行混合处理，得到化学式Ⅰ的前驱体；按照化学式Ⅱ所示Na0.91Ni0.26Fe0.24Mn0.41Cu0.08Al0.01O2所含金属元素摩尔比将NiO、ZnO、Mn2O3、Fe2O3、CuO、Al2O3于800转/分钟的转速下进行球磨处理5小时，再按比例加入碳酸钠进行混合处理，得到化学式Ⅱ的前驱体；
S2：分别将化学式Ⅰ和化学式Ⅱ的前驱体于马弗炉中进行烧结处理，粉碎，分别得到化学式Ⅰ和化学式Ⅱ所示镍铁锰基钠电正极活性材料，然后按照式Ⅱ与式Ⅰ的摩尔比为3:1的比例干混形成混合物；其中，烧结处理的条件为：温度：800℃；时间：8h；升温速率：10℃/min；氧气气氛。
实施例A11
本实施例提供一种正极材料组合物及其制备方法。该正极材料组合物包括两种镍铁锰基钠电正极活性材料，该两种镍铁锰基钠电正极活性材料按下表1中的比例进行物理混合形成的混合物。
该正极材料组合物制备方法包括如下步骤：
S1：按照化学式Ⅰ所示Na0.88Ni0.21Fe0.30Mn0.38Mg0.08Sn0.03O2所含金属元素摩尔比将NiO、TiO2、Mn2O3、Fe2O3、SnO2于800转/分钟的转速下进行球磨处理5小时，再按比例加入碳酸钠进行混合处理，得到化学式Ⅰ的前驱体；按照化学式Ⅱ所示Na0.91Ni0.26Fe0.24Mn0.41Cu0.08Al0.01O2所含金属元素摩尔比将NiO、ZnO、Mn2O3、Fe2O3、CuO、Al2O3于800转/分钟的转速下进行球磨处理5小时，再按比例加入碳酸钠进行混合处理，得到化学式Ⅱ的前驱体；
S2：分别将化学式Ⅰ和化学式Ⅱ的前驱体于马弗炉中进行烧结处理，粉碎，分别得到化学式Ⅰ和化学式Ⅱ所示镍铁锰基钠电正极活性材料，然后按照式Ⅱ与式Ⅰ的摩尔比为3:1的比例干混形成混合物；其中，烧结处理的条件为：温度：800℃；时间：8h；升温速率：10℃/min；氧气气氛。
对比例A1
本对比例提供一种正极材料组合物及其制备方法。该正极材料组合物包括两种镍铁锰基钠电正极活性材料，该两种镍铁锰基钠电正极活性材料按下表1中的比例进行物理混合形成的混合物。
该正极材料组合物制备方法包括如下步骤：
S1：按照化学式Ⅰ所示Na0.88Ni0.15Fe0.30Mn0.38Zn0.14Ca0.03O2所含金属元素摩尔比将NiO、 ZnO、Mn2O3、Fe2O3、CaO于800转/分钟的转速下进行球磨处理5小时，再按比例加入碳酸钠进行混合处理，得到化学式Ⅰ的前驱体；按照化学式Ⅱ所示Na0.91Ni0.26Fe0.24Mn0.37Cu0.12Al0.01O2所含金属元素摩尔比将NiO、ZnO、Mn2O3、Fe2O3、CuO、Al2O3于800转/分钟的转速下进行球磨处理5小时，再按比例加入碳酸钠进行混合处理，得到化学式Ⅱ的前驱体；
S2：分别将化学式Ⅰ和化学式Ⅱ的前驱体于马弗炉中进行烧结处理，粉碎，分别得到化学式Ⅰ和化学式Ⅱ所示镍铁锰基钠电正极活性材料，然后按照式Ⅱ与式Ⅰ的摩尔比为1:10的比例干混形成混合物；其中，烧结处理的条件为：温度：800℃；时间：8h；升温速率：10℃/min；氧气气氛。
2.正极和钠离子电池单体实施例
实施例B1至实施例B11
本实施例B1至实施例B11分别提供一种钠离子电池单体，各钠离子电池单体包括正极片、隔离膜和负极片形成的电极组件，还包括电解液。
其中，实施例B1至实施例B11中的钠离子电池单体组装如下：
正极片：钠离子正极活性材料、导电剂碳纳米管、导电剂炭黑、粘结剂聚偏氟乙烯(PVDF)按重量比95:0.5:2:2.5在适量的溶剂NMP中充分搅拌混合，形成均匀的正极浆料；将正极浆料均匀涂覆于13μm的正极集流体铝箔的表面上，经干燥、冷压后，得到实施例B1至实施例B10所含的正极极片；其中，钠离子正极活性材料分别为上述实施例A1至实施例A10中的正极材料组合物；在实施例B11所含的正极极片是将实施例B1所含正极极片是以实施例A11中的正极材料组合物作为正极材料，且其所含碳纳米管替换成碳纤维，并控制其含量为0.8％，如表2中所示，实施例B1所含正极片中的导电剂总含量与实施例B1的正极片所含导电剂总含量相同。
负极片：将硬碳、导电剂SP、CMC粘结剂按重量比8:1:1加入去离子水中充分搅拌混合，形成均匀的负极浆料；将极浆料均匀涂覆于6μm的铜箔的表面上，经干燥、冷压后，得到负极片。
电解液：在含水量小于10ppm的环境下，将非水有机溶剂碳酸乙烯酯EC、碳酸二乙酯DMC按照体积比1:1进行混合得到电解液溶剂，随后将六氟磷酸钠和混合后的溶剂混合，配置成钠盐浓度为1mol/L的电解液。
隔离膜：采用多孔聚乙烯(PE)膜作为隔离膜。
电池组装：将上述各正极片、隔离膜和负极片分别按顺序叠设，使隔离膜处于正极片与负极片中间起到隔离的作用，并经叠片工艺得到电极组件。将各电极组件分别置于外包装中，干燥后注入电解液，经过真空封装、静置、化成、整形等工序，分别得到实施例B1至实施例B11中的钠离子电池单体。其中，实施例B1中所含的钠离子正极活性材料为上述实施例A1中的正极材料组合物，实施例B2中所含的钠离子正极活性材料为上述实施例A2中的正极材料组合物，依次类推，实施例B11中所含的钠离子正极活性材料为上述实施例A11中的正极材料组合物。
对比例B1
本对比例B1提供一种钠离子电池单体，各钠离子电池单体包括正极片、隔离膜和负极片形成的电极组件，还包括电解液。
其中，对比例B1中的钠离子电池单体均参考实施例B1中的钠离子电池单体制备。不同在于：
在对比例B1的钠离子电池单体中，钠离子电池单体的正极片所含钠离子正极活性材料分别对比例A1中的正极材料组合物。
2.各实施例中正极材料组合物和钠离子电池单体相关性能检测：
2.1各实施例正极材料组合物的表征和相关性能测试：
将上述实施例A1至实施例A11和对比例A1提供的正极材料组合物分别按照如下方法进行下述表1中相关特征检测，检测的结果如表1中所示：
镍铁锰基钠电正极活性材料的元素含量检测方法：采用Agilent ICP-OES730得到 电感耦合等离子体发射光谱(ICP)，然后ICP结果分别计算实施例A1至实施例A11和对比例A1提供的正极材料组合物中各金属元素含量，根据各组合物中各镍铁锰基钠电正极活性材料摩尔混合比例换算单位摩尔量的正极材料组合物中各金属元素的摩尔含量。
充/放电克容量检测方法：按照上文本申请实施例正极材料组合物的充/放电克容量检测方法分别对实施例A1至实施例A11和对比例A1提供的正极材料组合物的充/放电克容量进行测定。
2.2各实施例中钠离子电池单体及其所含正极片相关性能测试：
将上述实施例B1至实施例B11和对比例B1中提供的钠离子电池单体及其所含正极片分别按照如下方法进行下述表2中相关性能检测，检测的结果如表2中所示：
CW检测方法：将实施例B1至实施例B17和对比例B1至对比例B2中各电池单体中正极分别通过冲切机充成1540.25mm2的极片，通过称重减去铝箔重量，得到纯活性物质层的重量，记为活性物质层的重量/1540.25mm2。
正极片压实密度检测方法：该正极片压实密度具体可参考锂离子电池正极材料锰酸锂的首次放电比容量及首次充放电效率测试方法，详见GB/T 39864-2021标准或者GB/T 42161-2022。具体可参考如下参数的测试步骤：
将实施例B1至实施例B17和对比例B1至对比例B2中各电池单体中正极分别使用冲压机冲出直径为14mm的正极片，采用电子天平、台式数显测厚仪分别测量正极片的质量mc、厚度dc；采用冲片机冲出直径为14mm的足够数量的铝箔基片，用电子天平、台式数显测厚仪分别测量铝箔基片的质量mAl、厚度dAl；按照如下公式分别计算各正极片压实密度：
正极片压实密度
其中：ρc为正极片压实密度，单位为克每立方厘米(g/cm3)；
mc为正极片质量，单位为克(g)；
mAl为铝箔基片质量，单位为克(g)；
为正极片直径，单位为毫米(mm)；
dc为正极片厚度，单位为微米(μm)；
dAl为铝箔基片厚度，单位为微米(μm)。
循环保持率(％)：在25℃下分别将实施例B1至实施例B17和对比例B1至对比例B2中各电池单体以0.33C恒流充电至3.85V，然后以3.85V恒压充电至电流为0.05C，然后以1C恒流放电至1.5V，此为一个充放电循环。以首次放电的容量为100％，计算电池循环1000次后的容量保持率。电池循环1000次后的容量保持率(％)＝第1000次循环的放电容量/首次放电的容量×100％。
能量密度：分别将实施例B1至实施例B17和对比例B1至对比例B2中电池单体每个电池单体电芯在常温下以0.33C倍率充电至电压等于4.2V，再以0.33C倍率放电至电压等于2.0V，测得放电能量S0。然后测得与S0对应电池单体的质量M，根据S0/M公式计算电池单体能量密度(质量能量密度)。
电阻值(DCR)增长率(％)：在25℃下，将电池单体电芯以0.33C倍率恒流充电至电压为4.1V，静置5min，1C放电至1.5V，静置15min，再次以0.33C倍率恒流充电至电压为4.1V再以0.33C放电到50％SOC，静置30min后，记录电压，4C脉冲放电30s，记录脉冲放电后的电压。
在25℃下，将循环1000cls后电芯0.33C倍率恒流充电至电压为4.1V，静置5min，1C放电至1.5V，静置15min，再次以0.33C倍率恒流充电至电压为4.1V再以0.33C放电到50％SOC，静置30min后，记录电压，4C脉冲放电30s，记录脉冲放电后的电压。
根据公式计算得到DCR，计算公式为：DCR＝(静置结束电压-脉冲放电后电压)/脉冲电流。
DCR增长率＝1000圈循环后电芯DCR/初始电芯DCR。
表1
表2
基于上述表1和表2可知，由实施例和对比例比较可知，将本申请实施例正极材料组合物中镍元素、锰元素和铜元素各原料以及Q所示金属元素单种元素总摩尔含量调节和控制在一定的范围，能够提高对相应钠离子电池单体电芯的直流电阻(DCR)的稳定性，在相同充放电条件下，钠离子电池单体电芯的DCR增长率控制在相应的范围内。
进一步对比实施例A1至实施例A7与实施例A8至实施例A9、对比实施例B1至实施例B7与实施例B8至实施例B9可知，同时调节正极材料组合物中的铜元素和锌元素，能够相对明显的影响对应钠离子电池单体电芯DCR的稳定性，如将单摩尔量的 正极材料组合物中铜元素和锌元素分别调节到实施例A8和实施例A9时，电芯对应钠离子电池单体电芯的DCR增长率相对实施例B1至实施例B7中的钠离子电池单体电芯的DCR增长率要高。因此，在正极材料组合物中，总的铜元素摩尔含量和锌元素摩尔含量可以改善电池电芯DCR增长。
通过实施例A4、实施例A10至实施例A11和实施例B4、实施例B10至实施例B11可知，当将本申请实施例正极材料组合物所含的锌元素替换成镁元素、钛元素时，均能够使得含有对应正极材料组合物的钠离子电池单体电芯的DCR在充放电过程中保持相对稳定，如在相同充放电条件下，实施例B10至实施例B11中钠离子电池单体的DCR增长率均低于180％。
在此基础上，基于表1和表2可知，含有本申请实施例正极材料组合物具有相对高的克容量，对应的钠离子电池单体电芯同时具有良好的能量密度和循环性能。
基于表2可知，含有本申请实施例正极材料组合物的正极片可以做到较高的压实密度，因此，本申请实施例正极材料组合物能够使得极片具有相对高的极片压实密度。
最后应说明的是：以上各实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述各实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围，其均应涵盖在本申请的权利要求和说明书的范围当中。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (20)

  1. 一种正极材料组合物，其特征在于，包括至少两种镍铁锰基钠电正极活性材料，各所述镍铁锰基钠电正极活性材料物理混合，所述镍铁锰基钠电正极活性材料的混合物还含有Cu元素和Q元素，在单位摩尔量的所述正极材料组合物中，Na的总摩尔含量为0.78～1moL；
    Ni的总摩尔含量为0.12～0.38moL；
    Mn的总摩尔含量为0.18～0.48moL；
    Fe的总摩尔含量为0.18～0.35moL；
    Q的总摩尔含量为0.01～0.12moL；
    Cu的总摩尔含量为0.01～0.14moL；
    所述Q包括Zn、Mg、Ti中的至少一种元素。
  2. 如权利要求1所述的正极材料组合物，其特征在于，在单位摩尔量的所述正极材料组合物中，所述Na、Ni、Mn、Fe、Cu和Y中的至少一元素的摩尔含量为：
    所述Na的总摩尔含量为0.8～1moL；
    所述Ni的总摩尔含量为0.15～0.35moL；
    所述Mn的总摩尔含量为0.20～0.45moL；
    所述Fe的总摩尔含量为0.20～0.33moL；
    所述Q的总摩尔含量为0.01～0.06moL；
    所述Cu的总摩尔含量为0.02～0.09moL。
  3. 如权利要求1或2所述的正极材料组合物，其特征在于，至少一种所述镍铁锰基钠电正极活性材料还含有活性或/和惰性的掺杂金属元素，在单位摩尔量的所述正极材料组合物中，所述掺杂金属元素的总摩尔含量大于0，小于或等于为0.13moL；
    和/或
    在单位摩尔量的所述正极材料组合物中，所述Na元素摩尔含量与其他金属元素的总摩尔含量比为(0.81～0.89)：1；
    和/或
    所述Cu元素和Q元素分布在不同的镍铁锰基钠电正极活性材料中。
  4. 如权利要求1～3任一项所述的正极材料组合物，其特征在于，至少一种所述镍铁锰基钠电正极活性材料还含有活性或/和惰性的掺杂金属元素，在单位摩尔量的所述正极材料组合物中，所述掺杂金属元素的总摩尔含量大于0，小于或等于为0.1moL；
    和/或
    在单位摩尔量的所述正极材料组合物中，所述Na元素摩尔含量与其他金属元素的总摩尔含量比为(0.82～0.89)：1。
  5. 如权利要求3或4所述的正极材料组合物，其特征在于，所述掺杂金属元素包括V、Ca、Cr、Al、Sc、Sn、Sb、Zr、Nb、Ru、Ir中的至少一种。
  6. 如权利要求1～5任一项所述的正极材料组合物，其特征在于，含所述Q元素的所述镍铁锰基钠电正极活性材料包括如下(1)至(4)中的至少一者：
    (1)Dv50粒径为3～8μm；
    (2)Dv90粒径为8～16μm；
    (3)在3吨压力下的压实密度高于3.1g/cm3；
    (4)比表面积为0.4～1.0m2/g。
  7. 如权利要求1～6任一项所述的正极材料组合物，其特征在于，含所述Q元素的所述镍铁锰基钠电正极活性材料包括如下(1)至(4)中的至少一者：
    (1)Dv50粒径为4～6.5μm；
    (2)Dv90粒径为10～14μm；
    (3)在3吨压力下的压实密度为3.1～3.4g/cm3；
    (4)比表面积为0.6～0.9m2/g。
  8. 如权利要求1～7任一项所述的正极材料组合物，其特征在于，含所述Cu元素的所述镍铁锰基钠电正极活性材料包括如下(1)至(4)中的至少一者：
    (1)Dv50粒径为5～11μm；
    (2)Dv90粒径为13～19μm；
    (3)在3吨压力下的压实密度为3.0～3.3g/cm3；
    (4)比表面积为0.4～0.7m2/g。
  9. 如权利要求1～8任一项所述的正极材料组合物，其特征在于，含所述Cu元素的所述镍铁锰基钠电正极活性材料包括如下(1)至(4)中的至少一者：
    (1)Dv50粒径为6.5～10μm；
    (2)Dv90粒径为14.5～18μm；
    (3)在3吨压力下的压实密度为3.0～3.25g/cm3；
    (4)比表面积为0.5～0.6m2/g。
  10. 如权利要求1～9任一项所述的正极材料组合物，其特征在于，各所述镍铁锰基钠电正极活性材料独立的包括如下(1)至(2)中的至少一者：
    (1)晶体结构包括O3相层状金属氧化物，且所述O3相层状金属氧化物占所述层状氧化物总重量的95％以上；
    (2)包括单晶，所述单晶的形貌呈块状；
    和/或
    所述正极材料组合物在1.5～4.2V和0.1C的放电克容量为115～128mAh/g。
  11. 如权利要求1～10任一项所述的正极材料组合物，其特征在于，所述正极材料组合物在1.5～4.2V和0.1C的放电克容量为120～128mAh/g。
  12. 一种如权利要求1～11任一项所述正极材料组合物的制备方法，其特征在于，包括如下步骤：
    按照单位摩尔量的所述正极材料组合物所含所述Na、Ni、Mn、Fe、Q和Cu的摩尔含量比例，将至少两种镍铁锰基钠电正极活性材料进行物理混合，形成正极材料组合物。
  13. 一种正极，包括正极活性物质层，其特征在于：所述正极活性物质层包括权利要求1～11任一项所述的正极材料组合物。
  14. 如权利要求13所述的正极，其特征在于：所述正极活性物质层在集流体单面上的含量为260～350mg/1540.25mm2；和/或
    所述正极的极片压实密度为2.6～3.4g/cm3；和/或
    所述正极活性物质层的孔隙率为40％～70％；和/或
    所述正极为极片，且由所述极片的一个表面至相对的另一表面的厚度与集流体厚度比为7～15：1；和/或
    所述正极为极片，所述极片的膜片电阻为0.5～5mΩ；和/或
    所述正极活性物质层所含的导电剂包括线性导电剂。
  15. 如权利要求13或14所述的正极，其特征在于：所述正极活性物质层在集流体单面上的含量为280～320mg/1540.25mm2；和/或
    所述正极的极片压实密度为2.8～3.2g/cm3；和/或
    所述正极活性物质层的孔隙率为50％～65％；和/或
    所述正极为极片，且由所述极片的一个表面至相对的另一表面的厚度与集流体厚度比为8～14：1；和/或
    所述正极为极片，所述极片的膜片电阻为0.5～3mΩ。
  16. 如权利要求14所述的正极，其特征在于：所述线性导电剂包括如下(1)至(5)中的至少一者：
    (1)在所述正极活性物质层中的质量含量为比为0.1％～2.5％；
    (2)长径比为40～3000：1；
    (3)长度为0.5～5μm；
    (4)直径为2～10nm；
    (5)包括碳纳米管、碳纤维、导电氧化物纳米线中的至少一种。
  17. 如权利要求16所述的正极，其特征在于：所述线性导电剂包括如下(1)至(4)中的至少一者：
    (1)在所述正极活性物质层中的质量含量为比为0.3～0.7％；
    (2)长径比为50～2500：1；
    (3)长度为0.5～2μm；
    (4)直径为3～7nm。
  18. 一种钠电池，其特征在于，包括权利要求13～17任一项所述的正极。
  19. 如权利要求18所述的钠电池，其特征在于：所述钠电池为钠电池单体，所述钠电池单体包括如下(1)至(3)中的至少一者：
    (1)工作电压为1.5～4.0V；和/或
    (2)在1.5～4.0V下的能量密度120～130Wh/Kg；
    (3)经1000cls后钠电池单体电芯的直流电阻增长率低于180％。
  20. 一种用电装置，其特征在于：包括权利要求18或19所述的钠电池。
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