WO2024113299A1 - 正极材料及其制备方法和包含其的二次电池和用电装置 - Google Patents

正极材料及其制备方法和包含其的二次电池和用电装置 Download PDF

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WO2024113299A1
WO2024113299A1 PCT/CN2022/135799 CN2022135799W WO2024113299A1 WO 2024113299 A1 WO2024113299 A1 WO 2024113299A1 CN 2022135799 W CN2022135799 W CN 2022135799W WO 2024113299 A1 WO2024113299 A1 WO 2024113299A1
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ppm
optionally
positive electrode
substrate particles
total weight
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PCT/CN2022/135799
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English (en)
French (fr)
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吴凯
张其雨
吴奇
陈强
柳娜
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宁德时代新能源科技股份有限公司
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Priority to PCT/CN2022/135799 priority Critical patent/WO2024113299A1/zh
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the technical field of lithium batteries, and in particular to a positive electrode material and a preparation method thereof, as well as a secondary battery and an electrical device comprising the positive electrode material.
  • Lithium-ion batteries are increasingly favored by the battery industry for their lightweight, long life, clean and environmentally friendly advantages.
  • the positive electrode materials of lithium-ion batteries have always been the focus of research and development in the industry.
  • the mainstream positive electrode materials of lithium-ion batteries have met the requirements of increasingly higher energy density with their high capacity and high energy density, and are more favored.
  • such positive electrode materials have poor capacity, and may experience particle cracking and pulverization during the cycle, poor cycle performance, high impurity lithium content, easy gas production, and poor safety performance.
  • the present application is made in view of the above-mentioned problems, and its purpose is to provide a positive electrode material, including substrate particles having a chemical composition of formula (I):
  • the positive electrode material of the present application has good comprehensive performance: high discharge specific capacity, good cycle performance, low amount of impurity lithium and less gas production.
  • the formula (I) satisfies one or more of the following conditions (1) to (8):
  • M is selected from one or more of Zr, Al, Mg and Ti;
  • the doping weight of the M element is ⁇ the doping weight of the W element, and the weight ratio of the M element to the tungsten (W) element is optionally 1:(0.1-1), and more optionally 1:(0.1-0.5).
  • the positive electrode material that meets one or more of the above conditions has better performance.
  • the W content within a thickness of 40 nm from the grain boundary is at least 80% by weight, optionally at least 90% by weight, based on the total weight of W in the substrate particles. Almost all of the W element doped in the material is enriched at the grain boundary, which is beneficial to increase the compaction density and improve various properties.
  • the W content in the substrate particles is 100 to 200,000 ppm, optionally 100 to 3,000 ppm, and more optionally 500 to 2,500 ppm, which is beneficial to improving particle integrity and cycle performance.
  • the volume particle size distribution diameter distance (D v 90-D v 10)/D v 50 of the positive electrode material is 1.1-1.8, optionally 1.2-1.5, more optionally 1.25-1.45, which is conducive to achieving higher compaction density, improving capacity, etc.
  • the positive electrode material further comprises a coating layer disposed on the surface of the substrate particles, the coating layer comprising at least one of W, Co, Al and B elements; optionally, the coating layer comprises at least W element and/or B element; more optionally, the coating layer comprises W, Co, Al and B elements. This further improves the material cycle performance and helps reduce the impurity lithium content and safety performance.
  • the coating layer satisfies one or more of the following conditions (1) to (5):
  • the coating layer contains 100 ppm to 2000 ppm, optionally 500 ppm to 1000 ppm of W element, based on the total weight of the substrate particles;
  • the coating layer contains 100 ppm to 16000 ppm, optionally 1000 ppm to 13000 ppm of Co element, based on the total weight of the substrate particles;
  • the coating layer contains 100 ppm to 3000 ppm, optionally 500 ppm to 2000 ppm of Al element, based on the total weight of the substrate particles;
  • the coating layer contains 100 ppm to 2000 ppm, optionally 500 ppm to 1500 ppm of B element, based on the total weight of the substrate particles;
  • the coating layer contains W, Co, Al and B elements and the total amount of these four elements is 1000-22000 ppm, preferably 1000-15000 ppm, based on the total weight of the substrate particles. Coating various elements within such a range is more conducive to improving the performance of the material.
  • a second aspect of the present application provides a method for preparing a positive electrode material, wherein the positive electrode material comprises substrate particles having a chemical composition of formula (I):
  • the method comprises the following steps:
  • the positive electrode material prepared by the method of the present application has good comprehensive performance: high capacity, good cycle performance, low impurity lithium content and safety performance.
  • the particle size of the W source compound particles is 20 to 500 nm, optionally 50 to 300 nm; and/or wherein the W source compound is selected from one or more of WO 3 , H 2 WO 4 , Li 2 WO 4 , (NH 4 ) 2 WO 4 , MgWO 4 and Zr(WO 3 ) 2 ; optionally, selected from one or more of WO 3 , H 2 WO 4 and Li 2 WO 4 ; and/or wherein the amount of W element added is 100 to 200000 ppm, optionally 100 to 3000 ppm, more optionally 500 to 2500 ppm, based on the total weight of the precursor material.
  • the use of the above W source compound and its particle size is more conducive to the doping of W element into the grain boundary of the material during high temperature sintering.
  • the M source compound is selected from sulfates, nitrates, chlorides, carbonates, oxides, hydroxides, oxalates and acetates containing M elements, and is optionally an oxide of M element; optionally, M element is one or more of Zr, Al, Mg and Ti; optionally, the amount of M element added is 100 to 5000 ppm, optionally 500 to 3000 ppm, based on the total weight of the precursor material.
  • These compounds containing M elements are more conducive to uniformly doping M elements into the layered material lattice at high temperatures, and using such an addition amount is more conducive to improving the performance of the material.
  • step S1 satisfies at least one of the following conditions:
  • the added weight ratio of the M element to the W element is 1:(0.1-1), and optionally 1:(0.1-0.5);
  • the ratio of the molar amount of Li atoms to the total molar amount of Ni, Co, and Mn atoms is set to 1.01 to 1.25, and optionally 1.05 to 1.15.
  • the grinding and mixing is performed by mechanical milling or ball milling; optionally, the grinding and mixing is performed in a ball mill, optionally in a heated ball mill; optionally, the grinding speed is 500-3000r/min, optionally 1000-2000r/min; or 800-1500r/min; optionally, the grinding and mixing is performed at a temperature of 30-100°C, optionally 40-60°C.
  • the above process conditions can promote uniform mixing and stable attachment of the W source compound and the precursor material, which is conducive to W doping enrichment at the grain boundaries.
  • the method further comprises the step of providing a coating layer on the surface of the substrate particles, which comprises:
  • the substrate particles obtained from S1 or the sintered product obtained from S2 are mixed with an Al-containing compound and/or a B-containing compound and then sintered.
  • the material properties are further improved.
  • step S2 satisfies one or more of the following conditions:
  • the W-containing compound is selected from one or more of WO 3 , H 2 WO 4 , Li 2 WO 4 , (NH 4 ) 2 WO 4 , MgWO 4 , and Zr(WO 3 ) 2 ;
  • the amount of W element added is 100-2000 ppm, optionally 500-1000 ppm, based on the total weight of the precursor material, which is conducive to making the W-containing coating layer more uniform and improving the material properties.
  • step S2 satisfies one or more of the following conditions:
  • the Co-containing compound is selected from one or more of Co 3 O 4 , Co(OH) 2 , CoO, CoOOH, Co(CH 3 COO) 2 , CoC 2 O 4 , and CoCO 3 ;
  • the amount of Co added is 100 to 16000 ppm, preferably 1000 to 13000 ppm, based on the total weight of the precursor material. This is more conducive to reducing surface impurities of lithium and improving cycle performance.
  • the Al-containing compound is selected from one or more of Al 2 O 3 , Al(OH) 3 , Al 2 (SO 4 ) 3 , AlCl 3 and Al(NO 3 ) 3 ; and/or the amount of Al added is 100 to 3000 ppm, preferably 500 to 2000 ppm, based on the total weight of the precursor material. This can further improve the interface stability of the material particles and reduce the interface side reactions, thereby being more conducive to improving the circulation, storage and safety performance of the material.
  • the B-containing compound is selected from one or more of BCl 3 , B 2 (SO 4 ) 3 , B(NO 3 ) 3 , BN, B 2 O 3 , BF 3 , BBr 3 , BI 3 , H 2 BO 5 P, H 3 BO 3 , C 5 H 6 B(OH) 2 , C 3 H 9 B 3 O 6 , (C 2 H 5 O) 3 B and (C 3 H 7 O) 3 B, and/or the amount of B added is 100 to 2000 ppm, preferably 500 to 1500 ppm, based on the total weight of the precursor material. This can further reduce the content of impurities of lithium on the surface of the material, while increasing the capacity of the material, and can also further improve the interface side reactions of the material, and enhance the circulation, storage and safety performance of the material.
  • the volume particle size distribution diameter of the precursor material is 1.1 to 1.8, optionally 1.2 to 1.5; and/or the D v 50 of the precursor material is 5 ⁇ m to 15 ⁇ m, optionally 5 ⁇ m to 10 ⁇ m. This is conducive to obtaining the desired positive electrode material with a larger compaction density, thereby facilitating the realization of a higher capacity.
  • a third aspect of the present application provides a secondary battery, comprising the positive electrode material of the first aspect or the positive electrode material obtained by the method of the second aspect.
  • a fourth aspect of the present application provides an electrical device comprising a secondary battery selected from the group consisting of:
  • the positive electrode material of the present application has good comprehensive performance: higher capacity, better cycle performance, lower amount of impure lithium and lower gas production.
  • FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 1 .
  • FIG. 3 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG. 4 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application.
  • FIG. 6 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.
  • “Scope” disclosed in the present application is defined in the form of lower limit and upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range.
  • the scope defined in this way can be including end values or excluding end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected.
  • the numerical range "a-b" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers.
  • the numerical range "0-5" represents that all real numbers between "0-5" have been fully listed herein, and "0-5" is just the abbreviation of these numerical combinations.
  • a parameter is expressed as an integer ⁇ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • the method may further include step (c), which means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
  • the “include” and “comprising” mentioned in this application represent open-ended or closed-ended expressions.
  • the “include” and “comprising” may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.
  • the term "or” is inclusive.
  • the phrase “A or B” means “A, B, or both A and B”. More specifically, any of the following conditions satisfies the condition "A or B”: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
  • Lithium-ion batteries are increasingly favored by the battery industry for their advantages of light weight, long life, cleanliness and environmental protection.
  • the positive electrode material of lithium-ion batteries has always been the focus of research and development in the industry.
  • the mainstream positive electrode materials of lithium-ion batteries are lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide and nickel cobalt manganese ternary materials, and emerging materials such as NCA (nickel cobalt aluminum) system and LOL (lithium-rich manganese solid solution) have been added to them and have been widely used in commercial applications.
  • NCA nickel cobalt aluminum
  • LOL lithium-rich manganese solid solution
  • the ternary positive electrode materials in the prior art are prone to cracking and pulverization of material particles during the lithium insertion and extraction process, resulting in poor cycle performance.
  • the existing materials also have high levels of impure lithium and gas expansion, resulting in poor storage and safety performance.
  • the present application provides a positive electrode material and a preparation method thereof.
  • the positive electrode material of the present application has a relatively high capacity, and also has improved material structure stability and particle integrity, thereby improving long cycle performance. It also has reduced impure lithium content and gas production, thereby improving storage and safety performance.
  • the present application proposes a positive electrode material, comprising substrate particles having a chemical composition of formula (I):
  • the positive electrode material of the present application has good comprehensive performance: high discharge specific capacity, good cycle performance, low amount of impure lithium and less gas production.
  • the positive electrode material of the present application is doped with M element and tungsten (W) element at the same time, and W is enriched at the grain boundaries in the substrate particles, which makes the material have good lattice structure stability and particle integrity, and thus has ideal comprehensive performance: good discharge specific capacity, improved cycle performance, reduced impurity lithium content, higher compaction density and improved safety performance.
  • an element with a relative atomic mass of less than 150 or a stable valence state of more than +3 is selected as the M element.
  • Such an M element has a small atomic mass and a small radius, has an appropriate electrostatic repulsion with W, and migrates faster into the interior of the material during the sintering process, thereby inhibiting the migration of W into the interior of the material and making W more inclined to be enriched at the grain boundaries.
  • grain boundary refers to the boundary between primary particles in a secondary particle.
  • the non-agglomerated fine particle units are called “primary particles”, and the particles formed by the agglomeration of primary particles are called “secondary particles”.
  • the substrate particles are secondary particles.
  • the spherical particles are secondary particles, and the nanosheets that make up the secondary particles are primary particles.
  • the W element is enriched at the grain boundaries, that is, the W element is doped at the surface of each primary particle in the substrate particles.
  • the M element is uniformly doped in the crystal structure of the substrate particles.
  • uniformly doped means completely and uniformly distributed inside the material particles (or in the crystal structure).
  • M is selected from one or more of Zr, Al, Mg and Ti. These elements are doped as M elements, which are more helpful to stabilize the crystal structure of the material and promote W enrichment at the grain boundary, thereby improving the material performance.
  • formula (I) satisfies 0.8 ⁇ x ⁇ 1 and/or 0 ⁇ a ⁇ 0.08.
  • the coefficients x and a in the present application may be conventional, but further controlling these values may help improve material properties.
  • formula (I) satisfies 0 ⁇ b ⁇ 0.018 and/or 0 ⁇ c ⁇ 0.0013. This helps to improve the cycle performance of the material, reduce the amount of impurity lithium and gas production, and improve safety performance.
  • Such a positive electrode material has better performance.
  • the doping weight of the M element is greater than or equal to the doping weight of the W element.
  • the weight ratio of the M element to the W element is 1:(0.1-1), and more optionally 1:(0.1-0.5).
  • the contents of the M element and the W element satisfy the above relationship, which is more conducive to the enrichment of the W element at the grain boundary, and improves the structural stability and particle integrity of the material, improves the migration ability of active ions (such as Li + ) in the material, improves the cycle stability, increases the compaction density, reduces the amount of impurities, and improves the safety performance.
  • the W content within 40 nm thickness from the grain boundary is at least 80%, and optionally at least 90%.
  • the doped W element is almost entirely enriched at the grain boundary, which is beneficial to improving the structural integrity and stability of the material particles, increasing the compaction density, and improving the performance.
  • the amount of W is 100-200000 ppm, optionally 100-3000 ppm, and more optionally 500-2500 ppm, which is beneficial to improve particle integrity and cycle performance, while ensuring that the material has good electrochemical properties.
  • the doping amount of the W element refers to the amount of the W element in the base material particles.
  • the amount of M is 100-5000 ppm, optionally 500-3000 ppm. Including M in such a range is more conducive to W enrichment at grain boundaries and helps the material obtain ideal properties.
  • the volume particle size distribution diameter distance (D v 90-D v 10)/D v 50) of the positive electrode material is 1.1 to 1.8, optionally 1.2 to 1.5, and more optionally 1.25 to 1.45.
  • the positive electrode material of the present application has a volume particle size distribution diameter distance in the above range, which is more conducive to achieving a higher compaction density (for example, a compaction density of ⁇ 3.45 g/cc or even ⁇ 3.50 g/cc at a pressure of 5 tons), thereby helping to improve energy density and specific capacity.
  • volume particle size distribution diameter span is defined as the value of (D v 90 - D v 10) / D v 50, where D v 90, D v 10 and D v 50 represent the average particle sizes corresponding to 90%, 10% and 50% of the particles in the volume distribution, respectively.
  • the volume particle size distribution diameter span reflects the particle size distribution width of the material particles - the larger the diameter span, the wider the particle size distribution width.
  • D v 90, D v 10 and D v 50 can be measured by conventional methods and instruments in the art (e.g., using a laser particle size analyzer).
  • This article uses the parameter "compacted density” to quantitatively evaluate the hardness of the positive electrode material particles and the compacted density of the positive electrode sheets.
  • the compacted density test can be performed by any appropriate method known to those skilled in the art.
  • a positive electrode material of a certain mass m is placed in a cylindrical mold with an inner radius of R, and different pressures are applied by a press to test the particle size distribution under different pressures until a double peak appears in the particle size distribution under a certain pressure (this indicates that there are a large number of compressed particles in the tested material).
  • the density under this pressure is the compacted density; the higher the compacted density value, the higher the volume energy density of the material particles.
  • the compacted density is calculated by the following formula:
  • m is the mass of the material to be tested added to the mold
  • R is the inner radius of the mold
  • ⁇ H is the height difference before and after pressure is applied.
  • the positive electrode material of the present application further includes a coating layer disposed on the surface of the substrate particles, and the coating layer includes at least one of W, Co, Al and B.
  • the positive electrode material includes a coating layer including at least one of the above elements, which can effectively reduce the surface impurity lithium content and/or inhibit the interface side reaction, and further improve at least one of the capacity, cycle performance and safety performance of the positive electrode material.
  • miscellaneous lithium has the meaning generally understood by those skilled in the art, meaning a lithium source compound or its byproduct that is not completely reacted during the high-temperature sintering process of the material. It accumulates on the surface of the material, not only increasing the active ion migration impedance and causing a decrease in capacity, but also may produce gas (such as CO 2 , etc.), increasing safety risks.
  • miscellaneous lithium includes (but is not limited to) lithium carbonate and/or lithium hydroxide, etc.
  • the miscellaneous lithium content can be determined by any method known to those skilled in the art, for example, acid-base titration, etc.
  • the coating layer contains W and/or B elements; this is more conducive to improving the capacity and cycle performance of the material.
  • the coating layer includes W, Co, Al and B elements. This further improves the capacity and cycle performance of the material, and helps to reduce the content of impure lithium and safety performance.
  • the W and/or Co coating layer can optimize the enrichment of W at the grain boundary, reduce impure lithium on the surface of the material, improve interface stability, and improve cycle performance; the B and/or Al coating layer is conducive to improving the specific capacity of the material, alleviating interface side reactions, and is conducive to the performance of the material cycle performance.
  • the coating layer contains 100ppm to 2000ppm, optionally 500ppm to 1000ppm of W element, based on the total weight of the substrate particles. In some embodiments, the coating layer contains 100ppm to 16000ppm, optionally 1000ppm to 13000ppm of Co element, based on the total weight of the substrate particles. In some embodiments, the coating layer contains 100ppm to 3000ppm, optionally 500ppm to 2000ppm of Al element, based on the total weight of the substrate particles. In some embodiments, the coating layer contains 100ppm to 2000ppm, optionally 500ppm to 1500ppm of B element, based on the total weight of the substrate particles. Coating various elements in such a range is more conducive to improving the performance of the material.
  • the coating layer contains W, Co, Al and B elements, and the total amount of these four elements is 1000-22000 ppm, preferably 1000-15000 ppm, based on the total weight of the substrate particles.
  • the existence and thickness of the coating layer can be confirmed by conventional methods and instruments, for example, by scanning electron microscopy, transmission electron microscopy, etc., and the coating layer can be seen as an independent layer outside the substrate particles in the microscope field of view.
  • the content of various elements in the coating layer can also be determined by conventional methods and instruments, for example, quantitatively obtained by EDS element distribution test using a scanning electron microscope.
  • the coating layer has a conventional thickness range in the art; optionally, the coating layer has a thickness of 0.001 ⁇ m to 1 ⁇ m, optionally 0.01 ⁇ m to 0.5 ⁇ m.
  • the coating layer thickness within the above range is more conducive to the positive electrode material having better electrochemical performance and volume energy density.
  • Another aspect of the present invention provides a method for preparing a cathode material of formula (I),
  • the method comprises the following steps:
  • the positive electrode material prepared by the method of the present application has good comprehensive performance: high capacity, good cycle performance, low impurity lithium content and safety performance.
  • the particle size of the W source compound particles is 20 to 500 nm, optionally 50 to 300 nm.
  • the W source compound with the above particle size range is used to make it easier for W to be doped into the grain boundaries of the material during the sintering process.
  • the W source compound is selected from one or more of WO 3 , H 2 WO 4 , Li 2 WO 4 , (NH 4 ) 2 WO 4 , MgWO 4 and Zr(WO 3 ) 2 ; alternatively, selected from one or more of WO 3 , H 2 WO 4 and Li 2 WO 4.
  • W source compounds are more likely to promote the doping of W elements into the grain boundaries of the material during high temperature sintering.
  • the amount of W added is 100 to 3000 ppm, optionally 500 to 2500 ppm.
  • the amount of W added within the above range is conducive to improving the material structure stability, improving the cycle performance, and achieving a higher specific capacity.
  • the M source compound is selected from sulfates, nitrates, chlorides, carbonates, oxides, hydroxides, oxalates and acetates of the M element, and is optionally an oxide of the M element.
  • the M element is one or more of Zr, Al, Mg and Ti. These compounds containing the M element are more conducive to uniformly doping the M element into the layered material lattice at high temperatures and achieving structural stability of the material.
  • the amount of the M element added is 100 to 5000 ppm, optionally 500 to 3000 ppm, based on the total weight of the substrate particles, which can improve the cycle stability and specific capacity of the positive electrode material.
  • the ratio of the added amount of the M element to the W element in step S1 is 1:(0.1-1), and optionally 1:(0.1-0.5). In this way, the obtained positive electrode material has better performance.
  • the ratio of the molar amount of Li atoms to the total molar amount of Ni, Co, and Mn atoms is 1.01 to 1.25, and optionally 1.05 to 1.15.
  • the obtained positive electrode material has a higher discharge specific capacity and better cycle performance (for example, the material is not prone to irreversible phase change during the cycle).
  • Me may be used to represent the total molar amount of Ni, Co, and Mn, and the ratio between the molar amount of Li atoms and the total molar amount of Ni, Co, and Mn atoms may be represented as "Li/Me”.
  • the lithium source compound may be any conventional lithium source compound known to those skilled in the art.
  • the lithium source compound is selected from one or more of LiOH ⁇ H 2 O, Li 2 CO 3 , Li 2 SO 4 , LiNO 3 , LiC 2 O 4 , CH 3 COOLi, etc.
  • the use of the above lithium source compounds can help the positive electrode material have a stable layered structure and ensure high electrochemical performance.
  • the grinding and mixing is carried out by mechanical milling or ball milling. In some embodiments, the grinding and mixing is carried out in a ball mill, optionally in a heated ball mill. In some embodiments, optionally, the speed of the ball mill is 500 to 3000 r/min, optionally 1000 to 2000 r/min. In some embodiments, the grinding and mixing is carried out at a temperature of 30 to 100° C., optionally 40 to 60° C.
  • the use of the above-mentioned process conditions can promote uniform mixing and stable adhesion of the W source compound and the precursor material, which is conducive to the enrichment of W doping at the grain boundaries.
  • the sintering is performed at a temperature of 650 to 950° C. In some embodiments, the sintering is performed for 10 to 20 hours. In some embodiments, the sintering is performed in air or O 2 atmosphere. With the above process conditions, the desired positive electrode material can be obtained.
  • the method of the present application further comprises the step of providing a coating layer on the surface of the substrate particles, which comprises:
  • the substrate particles obtained from S1 or the sintered product obtained from S2 are mixed with an Al-containing compound and/or a B-containing compound and then sintered.
  • the material properties are further improved.
  • the coating of different elements is carried out in separate steps, not only based on the demand for sintering temperature for achieving the best coating effect of different elements, but also to enable different elements to be in a position in the coating layer that is more conducive to improving material properties.
  • the coating of W and/or Co is carried out first, that is, it is preferred that the coating containing W and/or Co is directly carried out on the surface of the substrate particles; in this way, the W element in the coating layer can supplement the insufficient W doping at the grain boundary in the S1 step, thereby helping to improve the integrity and cycle performance of the particles, while Co can reduce the impurity lithium content on the surface of the substrate particles, improve the interface stability, and improve the cycle performance.
  • Coating the coated or uncoated substrate particles with Al and/or B elements is beneficial to reduce the interface side reactions between the material and the electrolyte, and increase the capacity and improve the material cycle performance.
  • the W-containing compound in step S2, has a conventional particle size, and optionally, the particle size of the W-containing compound is 0.01-5 ⁇ m, more optionally 0.05-1 ⁇ m, and even more optionally 0.1-1 ⁇ m. Using W-containing compound materials with such a particle size range can make the coating more uniform.
  • the substrate particles obtained in step S1 are mixed with at least a W-containing compound and then sintered.
  • the W-containing compound is selected from one or more of WO 3 , H 2 WO 4 , Li 2 WO 4 , (NH 4 ) 2 WO 4 , MgWO 4 , and Zr(WO 3 ) 2. Selecting these W-containing compounds is more conducive to forming a stable coating layer, avoiding direct contact between the electrolyte and the substrate particles, and inhibiting interface side reactions.
  • step S2 based on the total weight of the precursor material, the amount of W added is 100-2000 ppm, optionally 100-1000 ppm. Adding W within the above range is more conducive to improving the material cycle performance.
  • the Co-containing compound is selected from one or more of Co 3 O 4 , Co(OH) 2 , CoO, CoOOH, Co(CH 3 COO) 2 , CoC 2 O 4 , and CoCO 3.
  • the above Co-containing compounds are more conducive to reducing surface impurities and improving cycle performance.
  • the Co-containing compound in step S2, has a conventional particle size, and optionally, the particle size of the Co-containing compound is 0.01 to 10 ⁇ m, and optionally exists in the form of particles of 0.1 to 1 ⁇ m.
  • the addition of the Co-containing compound in this particle size range has a better coating effect, is more conducive to reducing the amount of impurity lithium, and improves the cycle performance of the material.
  • the amount of Co element in the coating layer is 100 to 16000 ppm, preferably 1000 to 13000 ppm.
  • the above amount of Co coating is beneficial to reduce the impurity lithium on the surface of the substrate particles and improve the cycle performance of the positive electrode material.
  • the sintering is performed at a temperature of 500 to 800°C, preferably 550 to 750°C. In some embodiments, the sintering is performed for 5 to 15 hours, preferably 5 to 10 hours. In some embodiments, the sintering is performed in air or O2 atmosphere.
  • the sintering process is beneficial to further doping W6 + in some W-containing compounds into the grain boundaries of the positive electrode material substrate particles; at the same time, it is also beneficial to allow the Co-containing compound to be coated on the surface of the positive electrode material substrate particles and interact with the impurity lithium, thereby improving the material performance.
  • the B-containing compound is selected from one or more of BCl 3 , B 2 (SO 4 ) 3 , B(NO 3 ) 3 , BN, B 2 O 3 , BF 3 , BBr 3 , BI 3 , H 2 BO 5 P, H 3 BO 3 , C 5 H 6 B(OH) 2 , C 3 H 9 B 3 O 6 , (C 2 H 5 O) 3 B and (C 3 H 7 O) 3 B.
  • the coating amount of B is 100 to 2000 ppm, preferably 500 to 1500 ppm. Coating with the B-containing compound can further reduce the content of impurities of lithium on the surface of the material, while increasing the capacity of the material, and can also further improve the interface side reaction of the material, and enhance the circulation, storage and safety performance of the material.
  • step S3 the substrate particles obtained from S1 or the product obtained from S2 are mixed with at least a B-containing compound and then sintered.
  • the Al-containing compound is selected from one or more of Al 2 O 3 , Al(OH) 3 , Al 2 (SO 4 ) 3 , AlCl 3 and Al(NO 3 ) 3.
  • the Al coating amount is 100 to 3000 ppm, preferably 500 to 2000 ppm. Coating with the Al-containing compound can further improve the interface stability of the material particles and reduce the interface side reactions, thereby being more conducive to improving the circulation, storage and safety performance of the material.
  • the sintering is performed at 200-500°C, optionally 200-400°C. In some embodiments, the sintering is performed for 5-15 hours, optionally 5-10 hours. In some embodiments, the sintering is performed in air or O2 atmosphere.
  • the sintering process of the invention is conducive to coating the B compound and/or Al compound on the surface of the positive electrode material substrate particles, achieving a good coating effect.
  • the precursor material is in the form of particles, and the volume particle size distribution diameter is 1.1 to 1.8, optionally 1.2 to 1.5.
  • the D v 50 of the precursor material is 5 ⁇ m to 15 ⁇ m, optionally 5 ⁇ m to 10 ⁇ m. The use of such precursor material particles is conducive to obtaining the desired positive electrode material with a larger compaction density, thereby facilitating the realization of a higher capacity.
  • step S2 or step S3 can be performed in a suitable device known to those skilled in the art, such as a plowshare mixer, a high speed mixer or an inclined mixer.
  • Another aspect of the present application provides a positive electrode material obtained by the above method.
  • Another aspect of the present application provides a secondary battery, comprising the positive electrode material of the present application, the positive electrode material obtained by the method of the present application, or the positive electrode sheet of the present application.
  • Secondary batteries include battery cells, battery modules, and battery packs.
  • Another aspect of the present application provides an electrical device, comprising the secondary battery of the present application.
  • a secondary battery is provided.
  • a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator.
  • active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet.
  • the electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet.
  • the separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.
  • Another aspect of the present application provides a positive electrode plate, comprising the positive electrode material of the present application or the positive electrode material obtained by the method of the present application.
  • the positive electrode plate includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, and the positive electrode film layer includes the positive electrode material of the present application.
  • the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • aluminum foil may be used as the metal foil.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode film layer may also optionally include a binder.
  • the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • vinylidene fluoride-tetrafluoroethylene-propylene terpolymer vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer
  • the positive electrode film layer may further include a conductive agent, which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • a conductive agent which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N-methylpyrrolidone
  • the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer which is optionally arranged on at least one surface of the negative electrode current collector.
  • the negative electrode film layer comprises a negative electrode active material.
  • the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the metal foil copper foil may be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate.
  • the composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative electrode active material may be a negative electrode active material for a battery known in the art.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the negative electrode film layer may further include a binder.
  • the binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • a conductive agent which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).
  • a thickener eg, sodium carboxymethyl cellulose (CMC-Na)
  • the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.
  • a solvent such as deionized water
  • the electrolyte plays the role of conducting ions between the positive electrode and the negative electrode.
  • the present application has no specific restrictions on the type of electrolyte, which can be selected according to needs.
  • the electrolyte can be liquid, gel or all-solid.
  • the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.
  • the electrolyte salt may be selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, lithium tetrafluorooxalatophosphate.
  • the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • additives such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • the secondary battery further includes a separator.
  • the present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. In some embodiments, the isolation membrane can also have one or more coatings.
  • the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.
  • the secondary battery may include an outer package for packaging the positive electrode sheet, the negative electrode sheet and the electrolyte.
  • the positive electrode sheet, the negative electrode sheet and the separator may be laminated or wound to form a laminated structure battery cell or a wound structure battery cell, and the battery cell is packaged in the outer package; the electrolyte adopts the electrolyte described in the first aspect of the present application, and the electrolyte is infiltrated in the battery cell.
  • the number of batteries in the secondary battery may be one or more, which can be adjusted according to demand.
  • the present application provides an electrode assembly.
  • the positive electrode sheet, the negative electrode sheet and the separator can be made into an electrode assembly by a winding process or a lamination process.
  • the outer packaging can be used to encapsulate the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a soft package, such as a bag-type soft package.
  • the material of the soft package may be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), etc.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the present application has no particular restrictions on the shape of the secondary battery, which may be cylindrical, square, or any other shape.
  • FIG. 1 is a battery cell 5 of a square structure as an example.
  • the outer package may include a shell 51 and a cover plate 53.
  • the shell 51 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 shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity.
  • the positive electrode sheet, the negative electrode sheet and the isolation film can form an electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is encapsulated in the receiving cavity.
  • the electrolyte is infiltrated in the electrode assembly 52.
  • the number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • battery cells may be assembled into a battery module.
  • the number of battery cells contained in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG3 is a battery module 4 as an example.
  • a plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.
  • the battery modules described above may also be assembled into a battery pack.
  • the battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.
  • FIG4 and FIG5 are battery packs 1 as an example.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be covered on the lower box body 3 to form a closed space for accommodating the battery modules 4.
  • the plurality of battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electric device, the electric device includes the secondary battery provided in the present application.
  • the secondary battery can be used as a power source for the electric device, and can also be used as an energy storage unit for the electric device.
  • the electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.
  • a battery cell, a battery module or a battery pack can be selected according to its usage requirements.
  • Fig. 6 is an example of an electric device.
  • 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.
  • a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be thin and light, and a secondary battery may be used as a power source.
  • -S0 provided a precursor material of Ni 0.9 Co 0.05 Mn 0.05 (OH) 2 , with a D v 50 of 8.5 ⁇ m and a (D v90 -D v10 )/D v50 of 1.35.
  • WO 3 particle size 50nm
  • the precursor material are placed in a heated ball mill for ball milling (rotation speed of 2000r/min, temperature of 60°C) to obtain a mixture, wherein the amount of W added is 500ppm (based on the total weight of the precursor material).
  • LiOH ⁇ H 2 O, Al 2 O 3 and the above mixture are mixed so that the Li/Me molar ratio in the mixture is 1.15, and the amount of Al added is 500ppm (based on the total weight of the precursor material).
  • the weight of M element (here Al) added/the weight of W element added is 1:1.
  • the above mixture is sintered at 750°C for 20h in an O 2 atmosphere to obtain substrate particles.
  • the positive electrode material, polyvinylidene fluoride (PVDF) and conductive carbon (Super P) prepared above were added to methyl pyrrolidone (NMP) at a weight ratio of 90:5:5, stirred in a drying room to form a positive electrode slurry (solid content of 97.44%), and the positive electrode slurry was coated on aluminum foil at a loading amount of 176 mg/ cm2 , and then dried and cold pressed to form a positive electrode sheet.
  • PVDF polyvinylidene fluoride
  • Super P conductive carbon
  • the negative electrode active material artificial graphite, hard carbon, conductive agent acetylene black, binder styrene butadiene rubber (SBR), and thickener sodium carbon methyl cellulose (CMC) are fully stirred and mixed in a deionized water solvent system in a weight ratio of 90:5:2:2:1 to obtain a negative electrode slurry with a solid content of 96.5%.
  • the slurry is coated on a copper foil with a loading amount of 124 mg/ cm2 , dried, and cold pressed to obtain a negative electrode sheet.
  • PE polyethylene
  • LiPF 6 Lithium hexafluorophosphate
  • DMC dimethyl carbonate
  • DEC diethyl carbonate
  • EC ethylene carbonate
  • the obtained positive electrode sheet (20.8 cm 2 ), separator (22.4 cm 2 ), and negative electrode sheet (22.2 cm 2 ) were stacked in order, with the separator placed between the positive and negative electrodes to play a role of isolation, and wound to obtain a bare cell.
  • the bare cell was placed in an outer package, injected with 0.5 g of electrolyte and packaged to obtain a full battery.
  • the positive electrode sheet (1.54 cm 2 ) prepared in the above item 2, a lithium sheet as a negative electrode sheet, a separator and the above electrolyte were used to assemble a button cell in a button cell box.
  • the substrate particles were cut into sections using focused ion beam sputtering, and then observed and randomly selected in conventional mode under a scanning electron microscope. The selected position was then fixed and the scanning electron microscope voltage was adjusted to 15 kV. At this voltage, EDS element surface distribution was used to observe that the W element was concentrated at the grain boundaries of the substrate particles.
  • the change in the W content of a primary particle from the grain boundary to the interior of the particle was measured using EDS element line distribution.
  • the W content decreases from the grain boundary to the interior of the primary particle: in the primary particle, within 40 nm from the grain boundary, the W content is 84%, based on the total weight of W in the substrate particle.
  • the substrate particles are cut into sections by using focused ion beam sputtering or metallographic sample preparation, and the cross-sectional morphology inside the particles is observed using a conventional scanning electron microscope. Using EDS element surface distribution, it can be observed that the M element is evenly distributed on the cross-sectional surface of the substrate particles.
  • m is the mass of the material to be tested added to the mold
  • R is the inner radius of the mold
  • ⁇ H is the height difference of the material before and after pressure is applied.
  • Test method for initial gram capacity after power off :
  • Capacity retention rate (D 150 /D 1 ) ⁇ 100%
  • the impure lithium content of the material was tested by acid-base titration. 30g of the sample was placed in 100ml of pure water, stirred for 30min, and then allowed to stand for 5min. The sample was filtered and 10ml of the supernatant was titrated with 0.05mol/L hydrochloric acid standard solution. The pH electrode was used as the indicator electrode. The end point was determined by the sudden change in potential, and the impure lithium content of the positive electrode material was calculated.
  • the full battery cell with 100% state of charge (SOC) was stored at 70°C for 30 days, and the volume of the cell before and after storage was measured by the water displacement method.
  • SOC state of charge
  • the tested battery cell is left to stand and cooled to room temperature, and the gravity on the battery cell is measured with a balance, which reads F1.
  • the battery cell is then completely immersed in deionized water (density is known to be 1g/ cm3 ), and the balance reads F2.
  • the increase in the volume of the battery cell after storage relative to the volume of the battery cell before storage is calculated to be the gas production; the ratio of the gas production to the battery cell capacity (the battery cell design capacity is 4Ah) is the gas production per unit capacity (mL/Ah), which is recorded in the following Table 2.
  • Example 2 is substantially the same as Example 1, except that the particle size of the W source compound in step S1 is 100 nm, and the Li/Me molar ratio is modified to 1.1.
  • Example 3 is substantially the same as Example 1, except that the particle size of the W source compound in step S1 is 56 nm, and the Li/Me molar ratio is modified to 1.05.
  • Example 4 is substantially the same as Example 1, except that the particle size of the W source compound in step S1 is 68 nm, and the Li/Me molar ratio is modified to 1.2:1.
  • Example 5 is substantially the same as Example 1, except that the composition of the precursor in step S0 is Ni 0.64 Co 0.35 Mn 0.01 (OH) 2 . and the particle size of the W source compound in step S1 is 77 nm.
  • Example 6 is substantially the same as Example 1, except that the composition of the precursor in step S0 is Ni 0.64 Co 0.01 Mn 0.35 (OH) 2 , and the particle size of the W source compound in step S1 is 105 nm.
  • Example 7 is substantially the same as Example 1, except that the composition of the precursor in step S0 is Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 , and the particle size of the W source compound in step S1 is 89 nm.
  • Example 8 is substantially the same as Example 1, except that the composition of the precursor in step S0 is Ni 0.95 Co 0.025 Mn 0.025 (OH) 2 , and the particle size of the W source compound in step S1 is 95 nm.
  • Example 9 is substantially the same as Example 1, except that in step S1, the amount of Al element added is 29000 ppm, the amount of W element added is 900 ppm, and the particle size of the W source compound is 120 nm.
  • Example 10 is substantially the same as Example 1, except that in step S1, the amount of Al element added is 15000 ppm, the amount of W element added is 900 ppm, and the particle size of the W source compound is 85 nm.
  • Example 11 is substantially the same as Example 1, except that in step S1, the amount of Al element added is 5500 ppm, the amount of W element added is 19000 ppm, and the particle size of the W source compound is 90 nm.
  • Example 12 is basically the same as Example 1, except that in step S1, the amount of Al element added is 5500 ppm, the amount of W element added is 89000 ppm, and the particle size of the W source compound is 110 nm.
  • Example 13 is basically the same as Example 1, except that in step S1, the amount of Al element added is 5500 ppm, the amount of W element added is 155000 ppm, and the particle size of the W source compound is 90 nm.
  • Example 14 is substantially the same as Example 1, except that: in step S0, the Dv50 of the precursor is 9.5, and (D v90 -D v10 )/D v50 is 1.5; in step S1, the W source compound is replaced with H 2 WO 4 (particle size 94 nm), and the amount of W added is 1000 ppm, based on the total weight of the precursor material; the M source compound is ZrO 2 , and the added weight ratio of M to W is 1:0.33.
  • Example 15 is substantially the same as Example 1, except that: in step S0, the Dv50 of the precursor is 9, and (D v90 -D v10 )/D v50 is 1.2; in step S1, the W source compound is replaced with Li 2 WO 4 (particle size 68 nm), and the amount of W added is 1500 ppm, based on the total weight of the precursor material; the M source compound is TiO 2 , and the added weight ratio of M to W is 1:0.3.
  • Example 16 is substantially the same as Example 1, except that: the W source compound in step S1 is replaced with Li 2 WO 4 (particle size 72 nm), and the amount of W added is 1500 ppm, based on the total weight of the precursor material; the M source compound is MgO, and the weight ratio of M to W added is 1:1.
  • Example 17 is substantially the same as Example 1, except that the particle size of the W source compound in step S1 is 78 nm, the amount of Al added is 100 ppm, and the amount of W added is 100 ppm, based on the total weight of the precursor material.
  • Example 18 is substantially the same as Example 1, except that the particle size of the W source compound in step S1 is 90 nm, the amount of Al added is 2000 ppm, and the amount of W added is 2000 ppm, based on the total weight of the precursor material.
  • Example 19 is substantially the same as Example 1, except that the particle size of the W source compound in step S1 is 60 nm, the amount of Al added is 1000 ppm, and the amount of W added is 1000 ppm, based on the total weight of the precursor material.
  • Example 20 is substantially the same as Example 1, except that the particle size of the W source compound in step S1 is 120 nm, the amount of Al added is 5000 ppm, and the amount of W added is 1000 ppm, based on the total weight of the precursor material.
  • Example 21 is substantially the same as Example 1, except that the particle size of the W source compound in step S1 is 150 nm, the amount of Al added is 5000 ppm, and the amount of W added is 500 ppm, based on the total weight of the precursor material.
  • Example 22 is substantially the same as Example 1, except that the particle size of the W source compound in step S1 is 80 nm, the amount of Al added is 5000 ppm, and the amount of W added is 2500 ppm, based on the total weight of the precursor material.
  • Comparative Example 1 uses a positive electrode material in the prior art, whose chemical composition is LiNi 0.9 Co 0.05 Mn 0.05 O 2 , and the remaining steps are the same as those of Example 1.
  • Table 1 shows the relevant parameters of the substrate particles prepared in Examples 1-12:
  • Table 2 shows the performance test results of the positive electrode materials in Examples 1-22:
  • the positive electrode material of the present invention has a higher compaction density, a higher capacity and better cycle performance (having a higher capacity retention rate in a wide temperature range), and has a lower amount of impure lithium, less gas production, and is safer.
  • Example 23 is the same as Example 1 in step S1, except that after obtaining the substrate particles in step S1, the following step S2 is performed:
  • S2 The substrate particles obtained in S1 were mixed with H 2 WO 4 (particle size 0.05 ⁇ m) to make the W addition amount 2000 ppm (based on the total weight of the substrate particles). The mixture was sintered at 700° C. for 15 h in an O 2 atmosphere to obtain a positive electrode material having a W-containing coating layer.
  • Example 24 is the same as Example 1 in step S1, except that after obtaining the substrate particles in step S1, the following step S2 is performed:
  • S2 The substrate particles obtained in S1 are mixed with CoO (particle size 0.1 ⁇ m) to make the amount of Co added 16000 ppm (based on the total weight of the substrate particles).
  • the mixed material is sintered at 700°C for 15 h in an O2 atmosphere to obtain a positive electrode material having a Co-containing coating layer.
  • Example 25 is the same as Example 1 in step S1, except that after obtaining the substrate particles in step S1, the following step S3 is performed:
  • the substrate particles obtained in S1 are mixed with Al2O3 so that the added amount of Al is 3000ppm (based on the total weight of the substrate particles), and the mixture is sintered at 500°C for 5h in an O2 atmosphere to obtain a positive electrode material having an Al-containing coating layer.
  • Example 26 is the same as Example 1 in step S1, except that after obtaining the substrate particles in step S1, the following step S3 is performed:
  • the substrate particles obtained in S1 are mixed with B2O3 so that the added amount of B is 2000ppm (based on the total weight of the substrate particles), and the mixture is sintered at 500°C for 5h in an O2 atmosphere to obtain a positive electrode material having a B-containing coating layer.
  • Example 27 is the same as Example 1 in step S1, except that after obtaining the substrate particles in step S1, steps S2 and S3 as described below are performed:
  • S2 The substrate particles obtained in S1 were mixed with H2WO4 so that the amount of W added was 2000 ppm (based on the total weight of the substrate particles), and the mixture was sintered at 700°C for 15 h in an O2 atmosphere.
  • Example 28 is the same as Example 1 in step S1, except that after obtaining the substrate particles in step S1, steps S2 and S3 as described below are performed:
  • S2 The substrate particles obtained in S1 were mixed with CoO, and the amount of Co added was 16000 ppm (based on the total weight of the substrate particles).
  • the mixed material was sintered at 700° C. for 15 h in an O 2 atmosphere.
  • Example 29 is the same as Example 1 in step S1, except that after obtaining the substrate particles in step S1, steps S2 and S3 as described below are performed:
  • S2 The substrate particles obtained in S1 were mixed with CoO and H2WO4 , with the amount of Co added being 16000ppm and the amount of W added being 2000ppm, both based on the total weight of the substrate particles.
  • the mixture was sintered at 700°C for 15h in an O2 atmosphere.
  • S3 The sintered product obtained in S2 is mixed with Al 2 O 3 and B 2 O 3 , so that the added amount of Al is 3000 ppm, the added amount of B is 2000 ppm, the Al coating amount: B coating amount is 1.5:1, and the mixture is sintered at 500°C in an O 2 atmosphere for 5 hours to obtain a positive electrode material with a coating layer.
  • Example 29 The difference between Example 29 and Example 29 is that the contents of the elements in steps S2 and S3 are adjusted respectively.
  • the content details and performance test data are shown in Table 3-4 below.
  • the existence and thickness of the coating layer can be observed by scanning electron microscopy. In the microscope field, it can be seen that the coating layer is an independent layer outside the substrate particles. The content of various elements in the coating layer is quantitatively obtained by EDS element distribution test of scanning electron microscopy.

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Abstract

本申请提供了一种正极材料，包括式(I)的基材颗粒： Li 1+a[Ni xCo yMn zM bW c]O 2 (I) 其中，M选自Mo、Zr、Al、Ti、Sb、Nb、Te、Mg、Al、Ca、Zn和Sr中的一种或多种，0.6<x<1，0<y<0.4，0<z<0.4，0<a<0.2，0<b<0.1，0<c<0.1，x+y+z+b+c＝1；并且W富集于所述基材颗粒的晶界处。本申请的正极材料具有较高的比容量、较好的循环性能、较高的压实密度、减少的杂锂量和产气。本申请还提供了制备正极材料的方法，以及包括该材料的正极极片、二次电池和用电装置。

Description

正极材料及其制备方法和包含其的二次电池和用电装置 技术领域
本申请涉及锂电池技术领域，尤其涉及一种正极材料及其制备方法，以及包含该正极材料的二次电池和用电装置。
背景技术
锂离子电池以其轻量化、长寿命、清洁环保的优点越来越受到电池行业的青睐。锂离子电池的正极材料作为其关键材料一直以来是业内研究和发展的重点。目前，锂离子电池的主流正极材料以其高容量、高能量密度的特点，满足了越来越高的能量密度的要求，受到更多的青睐。但是，此类正极材料容量不佳，并且在循环过程中可能出现颗粒开裂、粉化，循环性能差，同时杂锂偏高易产气，安全性能差等问题。
因此，本领域需要一种能够改善至少一个上述问题、性能良好的正极材料。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种正极材料，包括化学组成为式(I)的基材颗粒：
Li 1+a[Ni xCo yMn zM bW c]O 2  (I)
其中，M选自Mo、Zr、Al、Ti、Sb、Nb、Te、Mg、Al、Ca、Zn和Sr中的一种或多种，0.6≤x<1，0<y<0.4，0<z<0.4，0<a<0.2，0<b<0.1，0<c<0.1，x+y+z+b+c＝1；并且W富集于所述基材颗粒的晶界处。本申请的正极材料具有良好的综合性能：高放电比容量、良好的循环性能、较低的杂锂量和较少的产气。
在任意实施方式中，所述式(I)满足以下条件(1)至(8)中的一项或多项：
(1)M选自Zr、Al、Mg和Ti中的一种或多种；
(2)0.8≤x<1；
(3)0<a<0.08；
(4)0<b<0.018；
(5)0<c<0.0013；
(6)b:c＝0.076～384，可选地b:c＝5～69，更可选地b:c＝13～69；
(7)(1+a):(x+y+z)＝1.01～1.25，可选地(1+a):(x+y+z)＝1.05～1.15；
(8)M元素的掺杂重量≥W元素的掺杂重量，可选地M元素与钨(W)元素的重量比为1:(0.1～1)，更可选地为1:(0.1～0.5)。满足上述条件的一个或多个的正极材料具有更加的性能。
在任意实施方式中，在所述基材颗粒中，自所述晶界起40nm厚度内的W含量为至少80重量％，可选地为至少90重量％，基于所述基材颗粒中W的总重量计。材料中所掺杂的W元素几乎全部富集于晶界处，有利于提高压实密度，改善各项性能。
在任意实施方式中，基于所述基材颗粒的总重量计，所述基材颗粒中W的含量为100～200000ppm，可选地为100～3000ppm，更可选地为500～2500ppm。这有利于改善颗粒完整性和循环性能等。
在任意实施方式中，所述正极材料的体积粒度分布径距(D v90-D v10)/D v50为1.1～1.8，可选地为1.2～1.5，更可选地1.25～1.45。这有利于实现更高的压实密度，提升容量等。
在任意实施方式中，所述正极材料还包括设置于所述基材颗粒表面的包覆层，所述包覆层包含W、Co、Al和B元素中的至少一种；可选地，所述包覆层至少包含W元素和/或B元素；更可选地，所述包覆层包括W、Co、Al和B元素。这进一步改善材料循环性能，利于降低杂锂含量和安全性能。
在任意实施方式中，所述包覆层满足以下条件(1)至(5)中的一项或多项：
(1)所述包覆层包含100ppm～2000ppm，可选地500ppm～1000ppm的W元素，基于所述基材颗粒的总重量计；
(2)所述包覆层包含100ppm～16000ppm，可选地1000ppm～13000ppm的Co元素，基于所述基材颗粒的总重量计；
(3)所述包覆层包含100ppm～3000ppm，可选地500ppm～2000ppm的Al元素，基于所述基材颗粒的总重量计；
(4)所述包覆层包含100ppm～2000ppm，可选地500ppm～1500ppm的B元素，基于所述基材颗粒的总重量计；
(5)所述包覆层包含W、Co、Al和B元素且这四种元素的总量为1000～22000ppm，优选为1000～15000ppm，基于所述基材颗粒总重量计。以这样的范围包覆各种元素，更有利于改善材料的性能。
本申请的第二方面提供一种制备正极材料的方法，所述正极材料包括化学组成为式(I)的基材颗粒：
Li 1+a[Ni xCo yMn zM bW c]O 2  (I)
其中，M选自Mo、Zr、Al、Ti、Sb、Nb、Te、Mg、Al、Ca、Zn和Sr中的一种或多种，0.6≤x<1，0<y<0.4，0<z<0.4，0<a<0.2，0<b<0.1，0<c<0.1，x+y+z+b+c＝1；并且W富集于所述基材颗粒的晶界处；
所述方法包括以下步骤：
-S0：提供前驱体材料，化学组成为Ni xCo yMn z(OH) 2,0.6≤x<1，0<y<0.4，0<z<0.4，且x+y+z＝1，
-S1：将所述前驱体材料与W源化合物研磨混合，再向其中加入Li源化合物和M源化合物充分混合，烧结混合物得到所述基材颗粒。采用本申请的方法制备得到的正极材料，具有良好的综合性能：高容量、良好的循环性能、低杂锂量和安全性能。
在任意实施方式中，所述W源化合物颗粒的粒径为20～500nm，可选地50～300nm；和/或其中所述W源化合物选自WO 3、H 2WO 4、Li 2WO 4、(NH 4) 2WO 4、MgWO 4和Zr(WO 3) 2中的一种或多种；可选地，选自WO 3、H 2WO 4和Li 2WO 4中的一种或多种；和/或其中W元素的加入量为100～200000ppm，可选地为100～3000ppm，更可选地为500～2500ppm，基于所述前驱体材料的总重量计。采用上述W源化合物及其粒径在高温烧结过程中更有利于W元素掺杂进材料晶 界中。
在任意实施方式中，所述M源化合物选自含M元素的硫酸盐、硝酸盐、氯化物、碳酸盐、氧化物、氢氧化物、草酸盐和醋酸盐，可选地为M元素的氧化物；可选地，M元素为Zr、Al、Mg和Ti中的一种或多种；可选地，所述M元素的加入量为100～5000ppm，可选地为500～3000ppm，基于所述前驱体材料的总重量计。这些含M元素的化合物更有利于在高温下使M元素均匀掺杂进层状材料晶格中，而采用这样的加入量更有利于改善材料的性能。
在任意实施方式中，S1步骤满足以下条件中的至少一项：
(1)M元素与W元素的加入重量之比为1:(0.1～1)，可选地为1:(0.1～0.5)；
(2)使Li原子摩尔量与Ni、Co、Mn原子的总摩尔量之间的比值为1.01～1.25，可选地为1.05～1.15。
这使所获得的正极材料具有较高放电比容量同时具有较好的循环性能。
在任意实施方式中，所述研磨混合采用机械磨或球磨方式进行；可选地，所述研磨混合在球磨机，可选地在加热型球磨机中进行；可选地，所述研磨转速为500～3000r/min，可选地为1000～2000r/min；或800～1500r/min；可选地，所述研磨混合在30～100℃，可选地40～60℃的温度下进行。采用上述工艺条件能够促进W源化合物与前驱体材料的均匀混合并稳定附着，有利于W掺杂富集于晶界处。
在任意实施方式中，所述方法还包括在所述基材颗粒表面设置包覆层的步骤，其包括：
-S2：将由S1得到的基材颗粒与含W化合物和/或含Co化合物混合后烧结；和/或
-S3：将由S1得到的基材颗粒或由S2得到的烧结物与含Al化合物和/或含B化合物混合后烧结。
通过用上述包覆步骤对基材颗粒进行包覆，进一步改善材料性能。
在任意实施方式中，步骤S2满足以下条件中的一项或多项：
(1)所述含W化合物选自WO 3、H 2WO 4、Li 2WO 4、(NH 4) 2WO 4、MgWO 4、Zr(WO 3) 2中的一种或多种；
(2)W元素的加入量为100～2000ppm，可选地为500～1000ppm，基于所述前驱体材料的总重量计。这有利于含W包覆层更均匀，有利于改善材料性能。
在任意实施方式中，步骤S2满足以下条件中的一项或多项：
(1)所述含Co化合物选自Co 3O 4、Co(OH) 2、CoO、CoOOH、Co(CH 3COO) 2、CoC 2O 4、CoCO 3中的一种或多种；
(2)Co的加入量为100～16000ppm，优选为1000～13000ppm，基于所述前驱体材料的总重量计。这更有利于减少表面杂锂，提升循环性能。
在任意实施方式中，在步骤S3中，所述含Al化合物选自Al 2O 3、Al(OH) 3、Al 2(SO 4) 3、AlCl 3和Al(NO 3) 3中的一种或多种；和/或Al的加入量为100～3000ppm，优选为500～2000ppm，基于所述前驱体材料的总重量计。这能进一步提升材料颗粒的界面稳定性，减少界面副反应，从而更有利于提升材料的循环、存储及安全性能。
在任意实施方式中，在步骤S3中，所述含B化合物选自BCl 3、B 2(SO 4) 3、B(NO 3) 3、BN、B 2O 3、BF 3、BBr 3、BI 3、H 2BO 5P、H 3BO 3、C 5H 6B(OH) 2、C 3H 9B 3O 6、(C 2H 5O) 3B和(C 3H 7O) 3B中的一种或多种，和/或B的加入量为100～2000ppm，优选为500～1500ppm，基于所述前驱体材料的总重量计。这能进一步降低材料表面的杂锂含量，同时提高材料的容量，此外还可以进一步改善材料的界面副反应，提升材料的循环、存储及安全性能。
在任意实施方式中，所述前驱体材料的体积粒度分布径距为1.1～1.8，可选地为1.2～1.5；和/或所述前驱体材料的D v50为5μm～15μm，可选地5μm～10μm。有利于获得期望的具有较大压实密度的正极材料，从而有利于实现较高的容量。
本申请的第三方面提供一种二次电池，包括第一方面的正极材料或由第二方面的方法获得的正极材料。
本申请的第四方面提供一种用电装置，包括选自权利要求19所述的二次电池。
本申请的正极材料具有良好的综合性能：较高容量、较好的循环性能、较低的杂锂量和较低的产气量。
附图说明
图1是本申请一实施方式的二次电池的示意图。
图2是图1所示的本申请一实施方式的二次电池的分解图。
图3是本申请一实施方式的电池模块的示意图。
图4是本申请一实施方式的电池包的示意图。
图5是图4所示的本申请一实施方式的电池包的分解图。
图6是本申请一实施方式的二次电池用作电源的用电装置的示意图。
附图标记说明：
1电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳体；52电极组件；53顶盖组件
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的正极材料及其制备方法，以及包含该正极材料的正极极片、二次电池和电学装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和 80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
锂离子电池(锂二次电池)以其轻量化、长寿命、清洁环保的优点越来越受到电池行业的青睐。锂离子电池的正极材料作为其关 键材料一直以来是业内研究和发展的重点。目前，锂离子电池的正极材料主流有钴酸锂、磷酸铁锂、锰酸锂及镍钴锰三元材料，并且有NCA(镍钴铝)系、LOL(富锂锰固熔体)等新兴的材料加入其中，得到了广泛的商业化应用。其中，三元材料，特别是NCA材料，以其高容量、高能量密度的特点，满足了越来越高的能量密度的要求，受到更多的青睐。
但是，现有技术中的三元正极材料在脱嵌锂过程中容易出现材料颗粒产生裂纹、粉化，从而造成循环性能差，并且现有材料还存在杂锂偏高，产气膨胀，因此存储及安全性能较差问题。
针对现有技术此类材料存在的上述不足，本申请提供一种正极材料及其制备方法，本申请的正极材料具有较高容量，还具有提高的材料结构稳定性及颗粒完整性从而提升长循环性能，同时还具有降低的杂锂含量和产气，从而改善存储及安全性能。
正极材料
本申请的一个实施方式中，本申请提出了一种正极材料，包括化学组成为式(I)的基材颗粒：
Li 1+a[Ni xCo yMn zM bW c]O 2  (I)
其中，M选自Mo、Zr、Al、Ti、Sb、Nb、Te、Mg、Al、Ca、Zn和Sr中的一种或多种，0.6≤x<1，0<y<0.4，0<z<0.4，0<a<0.2，0<b<0.1，0<c<0.1，x+y+z+b+c＝1；并且W富集于所述基材颗粒的晶界处。
本申请的正极材料具有良好的综合性能：高放电比容量、良好的循环性能、较低的杂锂量和较少的产气。
本申请的正极材料中同时掺杂M元素和钨(W)元素并使W富集于基材颗粒中的晶界处，这使得材料具有良好的晶格结构稳定性和颗粒完整性，因此具有理想的综合性能：良好的放电比容量、提高的循环性能、降低的杂锂量、较高的压实密度和改善的安全性能。
对于掺杂的M元素，选择相对原子质量＜150或者稳定价态＞+3价的元素作为M元素，这样的M元素的原子质量小且半径小，与W之间存在适当的静电斥力作用且在烧结过程中向材料内部迁移 速度较快，从而抑制W向材料内部的迁移，使W更倾向于富集在晶界处。
本文中，“晶界”为二次颗粒中，各个一次颗粒之间的边界。
本文中，无团聚的细小颗粒单元(例如，单晶颗粒)称为“一次颗粒”，一次颗粒团聚后形成的颗粒称为“二次颗粒”。本文中，基材颗粒是二次颗粒。在扫描电子显微镜下观察，呈球形的是二次颗粒，而组成二次颗粒的纳米片就是一次颗粒。
本文中，W元素富集于晶界处，也即W元素掺杂于基材颗粒中各个一次颗粒的表面处。
在一些实施方式中，M元素均匀掺杂于基材颗粒的晶体结构中。本文中，“均匀掺杂”意为完全均匀地分布于材料颗粒内部(或晶体结构中)。
在一些实施方式中，式(I)中，M选自Zr、Al、Mg和Ti中的一种或多种。这些元素作为M元素进行掺杂，更有助于稳定材料晶体结构，促进W在晶界富集，从而改善材料性能。
在一些实施方式中，式(I)满足0.8≤x<1和/或0<a<0.08。本申请中系数x和a可以是常规的，但是进一步控制这些值，可有助于提高材料性能。
在一些实施方式中，式(I)满足0<b<0.018和/或0<c<0.0013。这样有助于改善材料的循环性能，降低杂锂量和产气量，改善安全性能。
在一些实施方式中，式(I)中，0<y<0.1；和/或0<z<0.1。本申请中，系数y和z的值是常规的且并不关键，在上述范围内即可。
在一些实施方式中，式(I)中，b:c＝0.076～384，可选地b:c＝5～69，更可选地b:c＝13～69。这样的正极材料具有更好的性能。
在一些实施方式中，式(I)满足(1+a):(x+y+z)＝1.01～1.25，可选地(1+a):(x+y+z)＝1.05～1.15，则正极材料性能更佳。
在一些实施方式中，M元素的掺杂重量≥W元素的掺杂重量，可选地，M元素与W元素的重量比为1:(0.1～1)，更可选地为1:(0.1～0.5)。M元素与W元素含量满足上述关系，更有利于W元素 在晶界处富集，并改善材料的结构稳定性和颗粒完整性，提高活性离子(例如Li +)在材料中的迁移能力，改善循环稳定性，提高压实密度，降低杂锂量，改善安全性能。
在一些实施方式中，其中在所述基材颗粒中，自所述晶界起40nm厚度内的W含量为至少80％，可选地为至少90％。在本申请的正极材料中，所掺杂的W元素几乎全部富集于晶界处，有利于改善材料颗粒的结构完整性和稳定性，提高压实密度，改善性能。
在一些实施方式中，基于所述基材颗粒的总重量计，W的量为100～200000ppm，可选地为100～3000ppm，更可选地为500～2500ppm。如此有利于改善颗粒完整性和循环性能等，同时确保材料具有良好的电化学性能。
本文中，W元素的掺杂量是指基材颗粒中W元素的量。
在一些实施方式中，基于所述基材颗粒的总重量计，M的量为100～5000ppm，可选地为500～3000ppm。以这样的范围包含M元素更有利于W在晶界处富集，并且有助于材料获得理想性能。
在一些实施方式中，所述正极材料的体积粒度分布径距(D v90-D v10)/D v50)为1.1～1.8，可选地为1.2～1.5，更可选地1.25～1.45。本申请的正极材料具有上述范围的体积粒度分布径距，更有利于实现较高的压实密度(例如，在5吨压力下的压实密度≥3.45g/cc，甚至≥3.50g/cc)，从而有利于提升能量密度和比容量。
本文中，“体积粒度分布径距”定义为(D v90-D v10)/D v50的值，其中，D v90、D v10和D v50分别表示体积分布中90％、10％和50％的颗粒所分别对应的平均粒度。体积粒度分布径距体现了材料颗粒的粒径分布宽度——径距越大，表明粒径分布宽度越宽。D v90、D v10和D v50可用本领域常规方法和仪器(例如，采用激光粒度仪)测得。
本文采用“压实密度”这一参数来量化评价正极材料颗粒的自身硬度及正极极片的压实密度。测试压实密度可通过本领域技术人员已知的任何适当方法进行。在本文中，将一定质量m的正极材料置于内圆半径为R的圆柱形模具中，通过压力机施加不同压力，以 测试不同压力下粒径分布，直至在某压力下粒径分布出现双峰(这表示被测材料中存在大量被压缩颗粒)，则该压力下的密度为压实密度；压实密度值越高，代表材料颗粒具有更高的体积能量密度。通过以下公式计算压实密度：
压实密度＝m/(π·R 2·ΔH)
其中，m为加入模具中的被测材料的质量，R为模具内半径，ΔH为施压前后的高度差。
在一些实施方式中，本申请的正极材料还包括设置于所述基材颗粒表面的包覆层，所述包覆层包含W、Co、Al和B元素中的至少一种。正极材料包括包含上述几种元素中至少一种的包覆层，可有效降低表面杂锂含量和/或抑制界面副反应，进一步改善正极材料的容量、循环性能和安全性能中的至少一者。
本文中，“杂锂”具有本领域技术人员通常所理解的含义，意为材料在高温烧结过程中未完全反应的锂源化合物或其副产物。其在材料表面积累，不仅增加活性离子迁移阻抗导致容量降低，还可能产生气体(如CO 2等)，增加安全风险。一般情况下，杂锂包括(但不限于)碳酸锂和/或氢氧化锂等。杂锂含量可以采用本领域技术人员已知的任意方法来确定，例如，酸碱滴定等。
在一些实施方式中，所述包覆层包含W和/或B元素；这样更有利于改善材料的容量和循环性能。在一些实施方式中，所述包覆层包括W、Co、Al和B元素。这进一步改善材料容量和循环性能，利于降低杂锂含量和安全性能。W和/或Co包覆层可优化W在晶界处的富集，降低材料表面杂锂，提高界面稳定性，改善循环性能；B和/或Al包覆层有利于提高材料比容量，缓解界面副反应，有利于材料循环性能的发挥。
在一些实施方式中，所述包覆层包含100ppm～2000ppm，可选地500ppm～1000ppm的W元素，基于所述基材颗粒总重量计。在一些实施方式中，所述包覆层包含100ppm～16000ppm，可选地1000ppm～13000ppm的Co元素，基于所述基材颗粒总重量计。在一些实施方式中，所述包覆层包含100ppm～3000ppm，可选地500 ppm～2000ppm的Al元素，基于所述基材颗粒总重量计。在一些实施方式中，所述包覆层包含100ppm～2000ppm，可选地500ppm～1500ppm的B元素，基于所述基材颗粒总重量计。以这样的范围包覆各种元素，更有利于改善材料的性能。
在一些实施方式中，所述包覆层包含W、Co、Al和B元素，且这四种元素的总量为1000～22000ppm，优选为1000～15000ppm，基于所述基材颗粒总重量计。
包覆层的存在及其厚度可通过常规方法和仪器确认，例如，可通过扫描电子显微镜、透射电子显微镜等观察到，在显微镜视野中可见包覆层是独立在基材颗粒外的层。包覆层中各种元素的含量也可通过常规方法和仪器来确定，例如，采用扫描电镜的EDS元素分布测试定量得到。
在一些实施方式中，包覆层具有本领域常规的厚度范围；可选地，所述包覆层厚度为0.001μm～1μm，可选地为0.01μm～0.5μm。包覆层的厚度处于上述范围内，更有利于正极材料具有较好的电化学性能和体积能量密度。
制备方法
本发明的另一方面提供一种制备式(I)的正极材料的方法，
Li 1+a[Ni xCo yMn zM bW c]O 2  (I)
其中，M选自Mo、Zr、Al、Ti、Sb、Nb、Te、Mg、Al、Ca、Zn和Sr中的一种或多种，0.6≤x<1，0<y<0.4，0<z<0.4，0<a<0.2，0<b<0.1，0<c<0.1，x+y+z+b+c＝1；并且W富集于所述基材颗粒的晶界处；
所述方法包括以下步骤：
-S0：提供前驱体材料，化学组成为Ni xCo yMn z(OH) 2,0.6≤x<1，0<y<0.4，0<z<0.4，且x+y+z＝1；
-S1：将所述前驱体材料与W源化合物研磨混合，再向其中加入Li源化合物和M源化合物充分混合，烧结混合物得到所述基材颗粒。采用本申请的方法制备得到的正极材料，具有良好的综合性能：高容量、良好的循环性能、低杂锂量和安全性能。
在一些实施方式中，所述W源化合物颗粒的粒径为20～500nm，可选地50～300nm。在本申请的方法中，采用具有上述粒径范围的W源化合物，更易于使W在烧结过程中掺杂到材料晶界中。
在一些实施方式中，所述W源化合物选自WO 3、H 2WO 4、Li 2WO 4、(NH 4) 2WO 4、MgWO 4和Zr(WO 3) 2中的一种或多种；可选地，选自WO 3、H 2WO 4和Li 2WO 4中的一种或多种。这些W源化合物在高温烧结过程中更容易促使W元素掺杂于材料晶界。
在一些实施方式中，基于所述基材颗粒的总重量计，W元素的加入量为100～3000ppm，可选地为500～2500ppm。W的加入量在上述范围内，既有利于提高材料结构稳定性，改善循环性能，实现较高的比容量。
在一些实施方式中，所述M源化合物选自M元素的硫酸盐、硝酸盐、氯化物、碳酸盐、氧化物、氢氧化物、草酸盐和醋酸盐，可选地为M元素的氧化物。在一些实施方式中，M元素为Zr、Al、Mg和Ti中的一种或多种。这些含M元素的化合物更有利于在高温使M元素均匀掺杂进层状材料晶格中，并实现材料的结构稳定性。
在一些实施方式中，基于所述基材颗粒的总重量计，所述M元素的加入量为100～5000ppm，可选地为500～3000ppm，基于所述基材颗粒的总重量计。如此可改善正极材料的循环稳定性和比容量。
在一些实施方式中，S1步骤满足M元素与W元素的加入量之比为1:(0.1～1)，可选地为1:(0.1～0.5)。如此，则所获得的正极材料具有更好的性能。
在一些实施方式中，S1步骤中使Li原子摩尔量与Ni、Co、Mn原子的总摩尔量之间的比值为1.01～1.25，可选地为1.05～1.15。如此，则所获得的正极材料具有较高的放电比容量和较好的循环性能(例如，材料在循环过程中不容易发生不可逆相变)。
本文中，为了简单起见，可用Me表示Ni、Co、Mn总摩尔量，则Li原子摩尔量与Ni、Co、Mn原子的总摩尔量之间的比值可表示为“Li/Me”。
所述锂源化合物可以是本领域技术人员已知的任意常规锂源化 合物。在一些实施方式中，所述锂源化合物选自LiOH·H 2O、Li 2CO 3、Li 2SO 4、LiNO 3、LiC 2O 4、CH 3COOLi等中的一种或多种。采用上述锂源化合物能够有利于正极材料具有稳定的层状结构，并保证较高的电化学性能。
在一些实施方式中，所述研磨混合采用机械磨或球磨方式进行。在一些实施方式中，所述研磨混合在球磨机，可选地在加热型球磨机中进行。在一些实施方式中，可选地，所述球磨机转速为500～3000r/min，可选地为1000～2000r/min。在一些实施方式中，所述研磨混合在30～100℃，可选地40～60℃的温度下进行。采用上述工艺条件能够促进W源化合物与前驱体材料的均匀混合并稳定附着，有利于W掺杂富集于晶界处。
在一些实施方式中，在所述步骤S1中，所述烧结是在650～950℃的温度下进行的。在一些实施方式中，所述烧结进行10～20h。在一些实施方式中，所述烧结是在空气或者O 2气氛中进行的。采用上述工艺条件，能够获得所期望的正极材料。
在一些实施方式中，本申请的方法还包括在所述基材颗粒表面设置包覆层的步骤，其包括：
-S2：将由S1得到基材颗粒与含W化合物和/或含Co化合物混合后烧结；和/或
-S3：将由S1得到的基材颗粒或由S2得到的烧结物与含Al化合物和/或含B化合物混合后烧结。
通过用上述包覆步骤对基材颗粒进行包覆，进一步改善材料性能。本申请的方法中，不同元素的包覆在分别的步骤中进行，不仅是基于不同元素实现最佳包覆效果对烧结温度的需求，更是为了使不同元素在包覆层中能处于更有利于改善材料性能的位置。相较于Al和/或B，W和/或Co的包覆先进行，也即，优选含W和/或Co的包覆直接在基材颗粒表面进行；这样，包覆层中的W元素可补充晶界处在S1步骤中W掺杂不充分，从而有助于改善颗粒的完整性和循环性能，而Co可以降低基材颗粒表面的杂锂含量，提高界面稳定性，改善循环性能。对经包覆或未经包覆的基材颗粒进行Al和/ 或B元素的包覆，均有利于减少材料与电解液之间的界面副反应，并提升容量，改善材料循环性能。
在一些实施方式中，在步骤S2中，所述含W化合物具有常规粒径，可选地，含W化合物的粒径为0.01～5μm，更可选地0.05～1μm，再更可选地0.1～1μm。采用这样粒径范围的含W化合物材料可使包覆更均匀。
在一些实施方式中，在所述步骤S2中，将由S1得到的基材颗粒至少与含W化合物混合后烧结。在一些实施方式中，在步骤S2中，所述含W化合物选自WO 3、H 2WO 4、Li 2WO 4、(NH 4) 2WO 4、MgWO 4、Zr(WO 3) 2中的一种或多种。选择这些含W化合物更利于形成稳定的包覆层，避免电解液与基材颗粒直接接触，抑制界面副反应。
在一些实施方式中，在步骤S2中，基于所述前驱体材料的总重量计，W元素的加入量为100～2000ppm，可选地为100～1000ppm。以上述范围加入W元素，更有利于改善材料循环性能。
在一些实施方式中，在步骤S2中，所述含Co化合物选自Co 3O 4、Co(OH) 2、CoO、CoOOH、Co(CH 3COO) 2、CoC 2O 4、CoCO 3中的一种或多种。采用的上述含Co化合物更有利于减少表面杂锂，提升循环性能。
在一些实施方式中，在步骤S2中，所述含Co化合物具有常规粒径，可选地，所述含Co化合物的粒径为0.01～10μm，可选地0.1～1μm的颗粒形式存在。以此粒径范围的含Co化合物的添加，包覆效果更好，更有利于降低杂锂量，提升材料的循环性能。
在一些实施方式中，在步骤S2中，基于所述正极材料的总重量计，包覆层中Co元素的量为100～16000ppm，优选为1000～13000ppm。采用上述量的Co包覆有利于减少基材颗粒表面的杂锂，提升正极材料的循环性能。
在一些实施方式中，在所述步骤S2中，所述烧结在500～800℃，优选为550～750℃温度下进行。在一些实施方式中，所述烧结进行5～15h，优选为5～10h。在一些实施方式中，所述烧结在空气或者 O 2气氛中进行。采用烧结工艺，有利于使部分含W化合物中的W 6+进一步掺杂进正极材料基材颗粒的晶界；同时，也有利于使含Co化合物包覆于正极材料基材颗粒表面并与杂锂发生作用，从而材料性能。
在一些实施方式中，在步骤S3中，所述含B化合物选自BCl 3、B 2(SO 4) 3、B(NO 3) 3、BN、B 2O 3、BF 3、BBr 3、BI 3、H 2BO 5P、H 3BO 3、C 5H 6B(OH) 2、C 3H 9B 3O 6、(C 2H 5O) 3B和(C 3H 7O) 3B中的一种或多种。在一些实施方式中，在步骤S3中，基于所述正极材料的总重量计，B的包覆量为100～2000ppm，优选为500～1500ppm。包覆含B化合物能进一步降低材料表面的杂锂含量，同时提高材料的容量，此外还可以进一步改善材料的界面副反应，提升材料的循环、存储及安全性能。
在一些实施方式中，在步骤S3中，将由S1得到的基材颗粒或由S2得到的产物至少与含B化合物混合后烧结。
在一些实施方式中，在步骤S3中，所述含Al化合物选自Al 2O 3、Al(OH) 3、Al 2(SO 4) 3、AlCl 3和Al(NO 3) 3中的一种或多种。在一些实施方式中，在步骤S3中，基于所述正极材料的总重量计，Al的包覆量为100～3000ppm，优选为500～2000ppm。包覆含Al化合物能进一步提升材料颗粒的界面稳定性，减少界面副反应，从而更有利于提升材料的循环、存储及安全性能。
在一些实施方式中，在步骤S3中，所述烧结在200～500℃，可选地200～400℃温度下进行。在一些实施方式中，所述烧结进行5～15h，可选地5～10h。在一些实施方式中，所述烧结在空气或者O 2气氛中进行。采用该发明烧结工艺有利于B化合物和/或Al化合物包覆在正极材料基材颗粒表面，实现良好的包覆效果。
在一些实施方式中，所述前驱体材料为颗粒形式，并且体积粒度分布径距为1.1～1.8，可选地为1.2～1.5。在一些实施方式中，所述前驱体材料的D v50为5μm～15μm，可选地5μm～10μm。采用这样的前驱体材料颗粒有利于获得期望的具有较大压实密度的正极材料，从而有利于实现较高的容量。
在一些实施方式中，步骤S2或步骤S3中的混合均可在本领域技术人员已知的适当的设备中进行，例如，犁刀混料机、高混机或者斜式混料机。
本申请的又一方面提供一种由根据上述方法获得的正极材料。
二次电池和用电装置
本申请的又一方面提供一种二次电池，包括本申请的正极材料、由本申请的方法获得的正极材料或本申请的正极极片。
二次电池包括电池单体形式、电池模块形式、电池包形式。
本申请的又一方面提供一种用电装置，包括本申请的二次电池。
另外，以下适当参照附图对本申请的电池单体、电池模块、电池包和用电装置进行说明。
本申请的一个实施方式中，提供一种二次电池。
通常情况下，二次电池包括正极极片、负极极片、电解质和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
[正极极片]
本申请的再一方面提供一种正极极片，包括本申请的正极材料或由本申请的方法得到的正极材料。
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，所述正极膜层包括本申请的正极材料。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(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)等的基材)上而形成。
在一些实施方式中，正极膜层还可选地包括粘结剂。作为示例，所述粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。
在一些实施方式中，正极膜层还可选地包括导电剂。作为示例，所述导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极材料、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
[负极极片]
负极极片包括负极集流体和任选地设置在负极集流体至少一个表面上的负极膜层。所述负极膜层包括负极活性材料。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极膜层设置在负极集流体相对的两个表面中的任意一者或两者上。
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(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)等的基材)上而形成。
在一些实施方式中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材 料和钛酸锂等。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施方式中，负极膜层还可选地包括粘结剂。所述粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。
在一些实施方式中，负极膜层还可选地包括导电剂。导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，负极膜层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极极片。
[电解质]
电解质在正极极片和负极极片之间起到传导离子的作用。本申请对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。
在一些实施方式中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。
在一些实施方式中，电解质盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二 氟二草酸磷酸锂、四氟草酸磷酸锂。
在一些实施方式中，溶剂可选自碳酸亚乙酯、碳酸亚丙酯、碳酸甲乙酯、碳酸二乙酯、碳酸二甲酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、氟代碳酸亚乙酯、甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、1,4-丁内酯、环丁砜、二甲砜、甲乙砜及二乙砜中的至少一种。
在一些实施方式中，所述电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
[隔离膜]
在一些实施方式中，二次电池中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。在一些实施方式中，所述隔离膜也可以具有一个或多个涂层。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
[外包装]
在一些实施方式中，二次电池可以包括外包装，用于封装正极极片、负极极片和电解质。作为一个示例，正极极片、负极极片和隔离膜可经叠片或卷绕形成叠片结构电芯或卷绕结构电芯，电芯封装在外包装内；电解质采用本申请第一方面所述的电解液，电解液浸润于电芯中。二次电池中电芯的数量可以为一个或几个，可以根据需求来调节。
在一个实施方式中，本申请提供一种电极组件。在一些实施方 式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。外包装可用于封装上述电极组件及电解质。
在一些实施方式中，二次电池的外包装可以是软包，例如袋式软包。软包的材质可以是塑料，如可包括聚丙烯(PP)、聚对苯二甲酸丁二醇酯(PBT)、聚丁二酸丁二醇酯(PBS)等中的一种或几种。在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图1是作为一个示例的方形结构的电池单体5。
在一些实施方式中，参照图2，外包装可包括壳体51和盖板53。其中，壳体51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51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。电池单体5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，电池单体可以组装成电池模块，电池模块所含电池单体的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图3是作为一个示例的电池模块4。参照图3，在电池模块4中，多个电池单体5可以是沿电池模块4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5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个电池单体5容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。
图4和图5是作为一个示例的电池包1。参照图4和图5，在电 池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
另外，本申请还提供一种用电装置，所述用电装置包括本申请提供的二次电池。所述二次电池可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。
作为所述用电装置，可以根据其使用需求来选择电池单体、电池模块或电池包。
图6是作为一个示例的用电装置。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。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用二次电池作为电源。
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。
实施例1
1.正极材料的制备
-S0：提供前驱体材料Ni 0.9Co 0.05Mn 0.05(OH) 2，D v50为8.5μm，(D v90-D v10)/D v50为1.35。
-S1：将WO 3(粒径50nm)、该前驱体材料放入加热球磨机中 进行球磨(转速为2000r/min，温度为60℃)得到混合料，其中使W加入量为500ppm(基于前驱体材料的总重量计)。将LiOH·H 2O、Al 2O 3及上述混合料混合，使混合物中Li/Me摩尔比为1.15，且Al加入量为500ppm(基于前驱体材料的总重量计)。M元素(此处为Al)加入重量/W元素加入重量为1:1。然后将上述混合物在O 2气氛中于750℃烧结20h，得到基材颗粒。
2.正极极片的制备
将上述制备的正极材料、聚偏二氟乙烯(PVDF)、导电碳(Super P)以重量比90:5:5加入甲基吡咯烷酮(NMP)中，在干燥房中搅拌制成正极浆料(固含量为97.44％)，在铝箔上以176mg/cm 2负载量涂覆正极浆料，再经干燥、冷压制成正极极片。
3.负极极片的制备
将负极活性物质人造石墨、硬碳、导电剂乙炔黑、粘结剂丁苯橡胶(SBR)、增稠剂碳甲基纤维素钠(CMC)按照重量比90:5:2:2:1在去离子水溶剂体系中充分搅拌混合均匀后得到固含量为96.5％的负极浆料，将其以124mg/cm 2的负载量涂覆于铜箔上烘干、冷压，得到负极极片。
4.隔离膜
市售的聚乙烯(PE)隔膜。
5.电解液的制备
将六氟磷酸锂(LiPF 6)加入到由碳酸二甲酯(DMC)、碳酸二乙酯(DEC)和碳酸乙烯酯(EC)以体积比1:1:1得到的混合溶剂中充分溶解，得到可供使用的电解液(锂盐浓度为1mol/L)。
6.电池(全电池)的制备
将得到的正极片(20.8cm 2)、隔离膜(22.4cm 2)、负极片(22.2cm 2)按顺序叠好，使隔离膜处于正负极中间起到隔离的作用，并卷绕得到裸电芯。将裸电芯置于外包装中，注入0.5g电解液并封装，得到全电池。
7.制备扣式电池：
采用上述第2项中制备的正极极片(1.54cm 2)、锂片作为负极 极片、隔离膜以及上述电解液，在扣电箱中组装成扣式电池。
二、性能测试
1.基材颗粒化学组成的表征：
取一定质量的粉末，用HF进行消解，加入ICP-OES仪中检测Li、Ni、Co、Mn、W、M元素含量，得到具体的元素含量摩尔比，得到具体化学组成(如表1所示)。
2.晶界中W元素富集部位的检测方法：
用聚焦离子束溅射将基材颗粒切出剖面，随后在扫描电镜下采用常规模式观察并随机选择颗粒切面图，随后固定选择位置，调节扫描电镜电压为15kV，在此电压下采用EDS元素面分布能观察到W元素集中分布于基材颗粒的晶界处。
采用EDS元素线分布测量某个一次颗粒从晶界到颗粒内部的W元素含量变化。对于实施例1的基材颗粒，可观察到W含量从晶界到一次颗粒内部呈下降趋势：在一次颗粒中，距离晶界40nm范围内，W的含量为84％，基于基材颗粒中W的总重量计。
3.材料颗粒中M元素均匀掺杂的验证：
用聚焦离子束溅射或金相制样等方法将基材颗粒切出剖面，在扫描电镜下采用常规模式观察颗粒内部的切面形貌。采用EDS元素面分布能观察到M元素均匀分布于基材颗粒的剖面上。
4.材料压实密度测试方法
将2g正极材料置于内圆半径为8mm的圆柱形模具中，通过压力机施加对模具中的材料施加不同压力，直至在某压力下粒径分布出现双峰。通过以下公式计算压实密度：
压实密度＝m/(π·R 2·ΔH)
其中，m为加入模具中的被测材料的质量，R为模具内半径，ΔH为施压前后的材料高度差。
5.扣电初始克容量测试方法：
在25℃恒温环境下，按照0.1C充电至4.3V，然后在4.3V下恒压充电至电流≤0.05mA，静置2min，此时的充电容量记为C0，然后按照0.1C放电至2.8V，此时的放电容量即为初始克容量。
6.全电初始克容量测试方法：
在25℃恒温环境下，将新制全电池静置5min，按照1/3C放电至2.8V，静置5min，按照1/3C充电至4.25V，然后在4.25V下恒压充电至电流≤0.05mA，静置5min，然后按照1/3C放电至2.8V，此时的放电容量即为初始克容量。
7.全电25/45℃循环性能测试：
在25℃的恒温环境下，按照1C充电至4.25V，然后在4.25V下恒压充电至电流≤0.05mA，静置5min，然后按照1C放电至2.8V，为循环一圈，测得放电容量记为D 1，循环150圈后，测得放电容量D 150，按照以下公式计算容量保持率：
容量保持率＝(D 150/D 1)×100％，
并记录于表1中。
在45℃的恒温环境下，按照上面步骤进行测试并计算容量保持率记录于表1中。
8.杂锂含量测试：
采用酸碱滴定法测试材料的杂锂含量。将30g样品放入100ml纯水中，搅拌30min后静置5min，抽滤，取10ml上清液，用0.05mol/L的盐酸标准溶液滴定，以pH电极为指示电极，借助于电位变化产生的突跃来确定终点，并计算正极材料的杂锂含量。
9.全电池的胀气测试：
将100％充电状态(SOC)的全电池电芯在70下存储30天，采用排水法分别测量存储前、后电芯的体积，具体步骤如下：
将被测电芯静置并冷却至室温，用天平测量电芯受到的重力，示数为F1；然后将电芯完全浸没于去离子水(密度已知为1g/cm 3)中，此时天平示数F2，则电芯受到的浮力F 浮＝F1-F2；然后根据阿基米德原理F 浮＝ρgV 排，计算V 排＝(F1-F2)/ρg，也即此时电芯的体积。
计算存储后的电芯体积相对于存储前的电芯体积的增加值，即为产气量；则产气量与电芯容量(电芯设计容量值为4Ah)的比值即为单位容量的产气量(mL/Ah)，记载于下表2中。
实施例2
实施例2与实施例1基本相同，不同之处在于，S1步骤中的W源化合物粒径为100nm，Li/Me摩尔比修改为1.1。
实施例3
实施例3与实施例1基本相同，不同之处在于，S1步骤中的W源化合物粒径为56nm，Li/Me摩尔比修改为1.05。
实施例4
实施例4与实施例1基本相同，不同之处在于，S1步骤中的W源化合物粒径为68nm，Li/Me摩尔比修改为1.2:1。
实施例5
实施例5与实施例1基本相同，不同之处在于，S0步骤中前驱体的组成为Ni 0.64Co 0.35Mn 0.01(OH) 2。，S1步骤中的W源化合物粒径为77nm。
实施例6
实施例6与实施例1基本相同，不同之处在于，S0步骤中前驱体的组成为Ni 0.64Co 0.01Mn 0.35(OH) 2，S1步骤中的W源化合物粒径为105nm。
实施例7
施例7与实施例1基本相同，不同之处在于，S0步骤中前驱体的组成为Ni 0.8Co 0.1Mn 0.1(OH) 2，S1步骤中的W源化合物粒径为89nm。
实施例8
实施例8与实施例1基本相同，不同之处在于，S0步骤中前驱体的组成为Ni 0.95Co 0.025Mn 0.025(OH) 2，S1步骤中的W源化合物粒径为95nm。
实施例9
实施例9与实施例1基本相同，不同之处在于，S1步骤中Al元素的加入量为29000ppm，W元素加入量为900ppm，W源化合物粒径为120nm。
实施例10
实施例10与实施例1基本相同，不同之处在于，S1步骤中Al 元素的加入量为15000ppm，W元素加入量为900ppm，W源化合物粒径为85nm。
实施例11
实施例11与实施例1基本相同，不同之处在于，S1步骤中Al元素的加入量为5500ppm，W元素加入量为19000ppm，W源化合物粒径为90nm。
实施例12
实施例12与实施例1基本相同，不同之处在于，S1步骤中Al元素的加入量为5500ppm，W元素加入量为89000ppm，W源化合物粒径为110nm。
实施例13
实施例13与实施例1基本相同，不同之处在于，S1步骤中Al元素的加入量为5500ppm，W元素加入量为155000ppm，W源化合物粒径为90nm。
实施例14
实施例14与实施例1基本相同，不同之处在于：S0步骤中前驱体的Dv50为9.5，(D v90-D v10)/D v50为1.5；S1步骤中的W源化合物更换为H 2WO 4(粒径94nm)，W的加入量为1000ppm，基于前驱体材料的总重量计；M源化合物是ZrO 2，M与W的加入重量比为1:0.33。
实施例15
实施例15与实施例1基本相同，不同之处在于：S0步骤中前驱体的Dv50为9，(D v90-D v10)/D v50为1.2；S1步骤中的W源化合物更换为Li 2WO 4(粒径68nm)，W的加入量为1500ppm，基于前驱体材料的总重量计；M源化合物是TiO 2，M与W的加入重量比为1:0.3。
实施例16
实施例16与实施例1基本相同，不同之处在于：S1步骤中的W源化合物更换为Li 2WO 4(粒径72nm)，W的加入量为1500ppm，基于前驱体材料的总重量计；M源化合物是MgO，M与W的加入 重量比为1:1。
实施例17
实施例17与实施例1基本相同，不同之处在于，S1步骤中的W源化合物粒径为78nm，Al加入量为100ppm，W加入量为100ppm，基于前驱体材料的总重量计。
实施例18
实施例18与实施例1基本相同，不同之处在于，S1步骤中的W源化合物粒径为90nm，Al加入量为2000ppm，W加入量为2000ppm，基于前驱体材料的总重量计。
实施例19
实施例19与实施例1基本相同，不同之处在于，S1步骤中的W源化合物粒径为60nm，Al加入量为1000ppm，W加入量为1000ppm，基于前驱体材料的总重量计。
实施例20
实施例20与实施例1基本相同，不同之处在于，S1步骤中的W源化合物粒径为120nm，Al加入量为5000ppm，W加入量为1000ppm，基于前驱体材料的总重量计。
实施例21
实施例21与实施例1基本相同，不同之处在于，S1步骤中的W源化合物粒径为150nm，Al加入量为5000ppm，W加入量为500ppm，基于前驱体材料的总重量计。
实施例22
实施例22与实施例1基本相同，不同之处在于，S1步骤中的W源化合物粒径为80nm，Al加入量为5000ppm，W加入量为2500ppm，基于前驱体材料的总重量计。
对比例1
对比例1采用现有技术中的正极材料，其化学组成为LiNi 0.9Co 0.05Mn 0.05O 2，其余步骤与实施例1相同。
表1示出了实施例1-12制备的基材颗粒的相关参数：
表1
Figure PCTCN2022135799-appb-000001
*基于基材颗粒中掺杂的W的总重量计，一次颗粒中自晶界起40nm的厚度内W的重量百分含量(wt.％)。
**基于所述基材颗粒的总重量计。
***体积粒度分布径距＝(D v90-D v10)/D v50。
表2中示出了实施例1-22中正极材料的性能测试结果：
表2
Figure PCTCN2022135799-appb-000002
由表1-2可见，比较实施例和对比例，本发明的正极材料具有较高的压实密度、较高的容量和较好的循环性能(在宽温度范围内均具有较高的容量保持率)，并且杂锂量较低，且产气少，更安全。
实施例23
实施例23与实施例1在S1步骤相同，不同之处在于，在S1步骤得到基材颗粒之后，进行以下S2步骤：
S2：将S1中得到的基材颗粒与H 2WO 4(粒径为0.05μm)混合，使W加入量为2000ppm(基于基材颗粒的总重量计)。将混合物料 在O 2气氛中于700℃烧结15h，得到具有含W包覆层的正极材料。
实施例24
实施例24与实施例1在S1步骤相同，不同之处在于，在S1步骤得到基材颗粒之后，进行以下S2步骤：
S2：将S1中得到的基材颗粒与CoO(粒径为0.1μm)混合，使Co加入量为16000ppm(均基于基材颗粒的总重量计)。将混合物料在O 2气氛中于700℃烧结15h，得到具有含Co包覆层的正极材料。
实施例25
实施例25与实施例1在S1步骤相同，不同之处在于，在S1步骤得到基材颗粒之后，进行以下S3步骤：
S3：将S1中得到的基材颗粒与Al 2O 3混合，使Al的加入量为3000ppm(基于基材颗粒的总重量计)，将混合物在O 2气氛中于500℃烧结5h，得到具有含Al包覆层的正极材料。
实施例26
实施例26与实施例1在S1步骤相同，不同之处在于，在S1步骤得到基材颗粒之后，进行以下S3步骤：
S3：将S1中得到的基材颗粒与B 2O 3混合，使B的加入量为2000ppm(基于基材颗粒的总重量计)，将混合物在O 2气氛中于500℃烧结5h，得到具有含B包覆层的正极材料。
实施例27
实施例27与实施例1在S1步骤相同，不同之处在于，在S1步骤得到基材颗粒之后，进行了如下所述的S2和S3步骤：
S2：将S1中得到的基材颗粒与H 2WO 4混合，使W加入量为2000ppm(基于基材颗粒的总重量计)，将混合物料在O 2气氛中于700℃烧结15h。
S3：将S2中得到的烧结物与B 2O 3混合，使B的加入量为2000ppm，将混合物在O 2气氛中于500℃烧结5h。得到具有含W和B包覆层的正极材料。
实施例28
实施例28与实施例1在S1步骤相同，不同之处在于，在S1步骤得到基材颗粒之后，进行了如下所述的S2和S3步骤：
S2：将S1中得到的基材颗粒与CoO混合，使Co的加入量为16000ppm(均基于基材颗粒的总重量计)。将混合物料在O 2气氛中于700℃烧结15h。
S3：将S2中得到的烧结物与B 2O 3混合，使B的加入量为2000ppm(基于基材颗粒的总重量计)，将混合物在O 2气氛中于500℃烧结5h，得到具有含Co和B包覆层的正极材料。
实施例29
实施例29与实施例1在S1步骤相同，不同之处在于，在S1步骤得到基材颗粒之后，进行了如下所述的S2和S3步骤：
S2：将S1中得到的基材颗粒与CoO、H 2WO 4混合，使Co加入量为16000ppm，W加入量为2000ppm，均基于基材颗粒的总重量计。将混合物料在O 2气氛中于700℃烧结15h。
S3：将S2中得到的烧结物与Al 2O 3、B 2O 3混合，使Al的加入量为3000ppm，B的加入量为2000ppm，Al包覆量:B包覆量为1.5:1，将混合物在O 2气氛中于500℃烧结5h，得到具有包覆层的正极材料。
实施例30-44
实施例与实施例29的区别在于，调整了步骤S2和S3中元素分别的含量，含量详情和性能测试数据详见下表3-4。
包覆层的存在及其厚度可通过扫描电子显微镜观察到，在显微镜视野中可见包覆层是独立在基材颗粒外的层。包覆层中各种元素的含量通过扫描电镜的EDS元素分布测试定量得到。
表3
Figure PCTCN2022135799-appb-000003
Figure PCTCN2022135799-appb-000004
表4
Figure PCTCN2022135799-appb-000005
Figure PCTCN2022135799-appb-000006
由表3-4可见，经过包覆后，本发明的正极材料的容量和循环性能得到进一步改善，还降低了表面杂锂量、显著改善胀气，从而提高了电池的安全性能。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。

Claims (20)

  1. 一种正极材料，包括化学组成为式(I)的基材颗粒：
    Li 1+a[Ni xCo yMn zM bW c]O 2  (I)
    其中，M选自Mo、Zr、Al、Ti、Sb、Nb、Te、Mg、Al、Ca、Zn和Sr中的一种或多种，0.6≤x<1，0<y<0.4，0<z<0.4，0<a<0.2，0<b<0.1，0<c<0.1，x+y+z+b+c＝1；并且W富集于所述基材颗粒的晶界处。
  2. 根据权利要求1所述的正极材料，其中所述式(I)满足以下条件(1)至(8)中的一项或多项：
    (1)M选自Zr、Al、Mg和Ti中的一种或多种；
    (2)0.8≤x<1；
    (3)0<a<0.08；
    (4)0<b<0.018；
    (5)0<c<0.0013；
    (6)b:c＝0.076～384，可选地b:c＝5～69，更可选地b:c＝13～69；
    (7)(1+a):(x+y+z)＝1.01～1.25，可选地(1+a):(x+y+z)＝1.05～1.15；
    (8)M元素的掺杂重量≥W元素的掺杂重量，可选地M元素与W元素的重量比为1:(0.1～1)，更可选地为1:(0.1～0.5)。
  3. 根据权利要求1或2所述的正极材料，其中在所述基材颗粒中，自所述晶界起40nm厚度内的W含量为至少80重量％，可选地为至少90重量％，基于所述基材颗粒中W的总重量计。
  4. 根据权利要求1至3中任一项所述的正极材料，其中基于所述基材颗粒的总重量计，所述基材颗粒中W的含量为100～200000ppm，可选地为100～3000ppm，更可选地为500～2500ppm。
  5. 根据权利要求1至4中任一项所述的正极材料，其中所述正极材料的体积粒度分布径距(D v90-D v10)/D v50为1.1～1.8，可选地为1.2～1.5，更可选地1.25～1.45。
  6. 根据权利要求1至5中任一项所述的正极材料，还包括设置于所述基材颗粒表面的包覆层，所述包覆层包含W、Co、Al和B元素中的至少一种；可选地，所述包覆层至少包含W元素和/或B元素；更可选地，所述包覆层包括W、Co、Al和B元素。
  7. 根据权利要求6所述的正极材料，其中所述包覆层满足以下条件(1)至(5)中的一项或多项：
    (1)所述包覆层包含100ppm～2000ppm，可选地500ppm～1000ppm的W元素，基于所述基材颗粒的总重量计；
    (2)所述包覆层包含100ppm～16000ppm，可选地1000ppm～13000ppm的Co元素，基于所述基材颗粒的总重量计；
    (3)所述包覆层包含100ppm～3000ppm，可选地500ppm～2000ppm的Al元素，基于所述基材颗粒的总重量计；
    (4)所述包覆层包含100ppm～2000ppm，可选地500ppm～1500ppm的B元素，基于所述基材颗粒的总重量计；
    (5)所述包覆层包含W、Co、Al和B元素且这四种元素的总量为1000～22000ppm，优选为1000～15000ppm，基于所述基材颗粒总重量计。
  8. 一种制备正极材料的方法，所述正极材料包括化学组成为式(I)的基材颗粒：
    Li 1+a[Ni xCo yMn zM bW c]O 2  (I)
    其中，M选自Mo、Zr、Al、Ti、Sb、Nb、Te、Mg、Al、Ca、Zn和Sr中的一种或多种，0.6≤x<1，0<y<0.4，0<z<0.4，0<a<0.2，0<b<0.1，0<c<0.1，x+y+z+b+c＝1；并且W富集于所述基材颗粒的 晶界处；
    所述方法包括以下步骤：
    -S0：提供前驱体材料，化学组成为Ni xCo yMn z(OH) 2,0.6≤x<1，0<y<0.4，0<z<0.4，且x+y+z＝1，
    -S1：将所述前驱体材料与W源化合物研磨混合，再向其中加入Li源化合物和M源化合物充分混合，烧结混合物得到所述基材颗粒。
  9. 根据权利要求8所述的方法，其中所述W源化合物颗粒的粒径为20～500nm，可选地50～300nm；和/或
    其中所述W源化合物选自WO 3、H 2WO 4、Li 2WO 4、(NH 4) 2WO 4、MgWO 4和Zr(WO 3) 2中的一种或多种；可选地，选自WO 3、H 2WO 4和Li 2WO 4中的一种或多种；和/或
    其中W元素的加入量为100～200000ppm，可选地为100～3000ppm，可选地为500～2500ppm，基于所述前驱体材料的总重量计。
  10. 根据权利要求8或9所述的方法，其中所述M源化合物选自含M元素的硫酸盐、硝酸盐、氯化物、碳酸盐、氧化物、氢氧化物、草酸盐和醋酸盐，可选地为M元素的氧化物；
    可选地，M元素为Zr、Al、Mg和Ti中的一种或多种；
    可选地，所述M元素的加入量为100～5000ppm，可选地为500～3000ppm，基于所述前驱体材料的总重量计。
  11. 根据权利要求8至10中任一项所述的方法，其中S1步骤满足以下条件中的至少一项：
    (1)M元素与W元素的加入重量之比为1:(0.1～1)，可选地为1:(0.1～0.5)；
    (2)使Li原子摩尔量与Ni、Co、Mn原子的总摩尔量之间的比值为1.01～1.25，可选地为1.05～1.15。
  12. 根据权利要求8至11中任一项所述的方法，其中所述研磨混合采用机械磨或球磨方式进行；可选地，所述研磨混合在球磨机，可选地在加热型球磨机中进行；
    可选地，所述研磨转速为500～3000r/min，可选地为1000～2000r/min；或800～1500r/min；
    可选地，所述研磨混合在30～100℃，可选地40～60℃的温度下进行。
  13. 根据权利要求8至12中任一项所述的方法，还包括在所述基材颗粒表面设置包覆层的步骤，其包括：
    -S2：将由S1得到的基材颗粒与含W化合物和/或含Co化合物混合后烧结；和/或
    -S3：将由S1得到的基材颗粒或由S2得到的烧结物与含Al化合物和/或含B化合物混合后烧结。
  14. 根据权利要求13所述的方法，其中步骤S2满足以下条件中的一项或多项：
    (1)所述含W化合物选自WO 3、H 2WO 4、Li 2WO 4、(NH 4) 2WO 4、MgWO 4、Zr(WO 3) 2中的一种或多种；
    (2)W元素的加入量为100～2000ppm，可选地为500～1000ppm，基于所述前驱体材料的总重量计。
  15. 根据权利要求13或14所述的方法，其中步骤S2满足以下条件中的一项或多项：
    (1)所述含Co化合物选自Co 3O 4、Co(OH) 2、CoO、CoOOH、Co(CH 3COO) 2、CoC 2O 4、CoCO 3中的一种或多种；
    (2)Co的加入量为100～16000ppm，优选为1000～13000ppm，基于所述前驱体材料的总重量计。
  16. 根据权利要求13至15中任一项所述的方法，其中在步骤 S3中，所述含Al化合物选自Al 2O 3、Al(OH) 3、Al 2(SO 4) 3、AlCl 3和Al(NO 3) 3中的一种或多种；和/或
    Al的加入量为100～3000ppm，优选为500～2000ppm，基于所述前驱体材料的总重量计。
  17. 根据权利要求13至16中任一项所述的方法，其中在步骤S3中，所述含B化合物选自BCl 3、B 2(SO 4) 3、B(NO 3) 3、BN、B 2O 3、BF 3、BBr 3、BI 3、H 2BO 5P、H 3BO 3、C 5H 6B(OH) 2、C 3H 9B 3O 6、(C 2H 5O) 3B和(C 3H 7O) 3B中的一种或多种，和/或
    B的加入量为100～2000ppm，优选为500～1500ppm，基于所述前驱体材料的总重量计。
  18. 根据权利要求8至17中任一项所述的方法，其中所述前驱体材料的体积粒度分布径距为1.1～1.8，可选地为1.2～1.5；和/或
    所述前驱体材料的D v50为5μm～15μm，可选地5μm～10μm。
  19. 一种二次电池，包括权利要求1至7中任一项所述的正极材料或由权利要求8至18中任一项所述的方法获得的正极材料。
  20. 一种用电装置，包括选自权利要求19所述的二次电池。
PCT/CN2022/135799 2022-12-01 2022-12-01 正极材料及其制备方法和包含其的二次电池和用电装置 WO2024113299A1 (zh)

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CN103563139A (zh) * 2011-05-31 2014-02-05 丰田自动车株式会社 锂二次电池
CN109461926A (zh) * 2018-11-09 2019-03-12 烟台卓能锂电池有限公司 一种锂离子电池正极材料及其制备方法、正极和锂离子电池
CN111094188A (zh) * 2017-07-12 2020-05-01 住友金属矿山株式会社 金属复合氢氧化物及其制造方法、非水电解质二次电池用正极活性物质及其制造方法、以及使用其的非水电解质二次电池
CN111422921A (zh) * 2019-12-31 2020-07-17 蜂巢能源科技有限公司 多晶高镍三元正极材料及其制备方法、正极片和锂离子电池
CN114436347A (zh) * 2022-03-21 2022-05-06 宁波容百新能源科技股份有限公司 一种高镍三元正极材料及其制备方法和应用

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Publication number Priority date Publication date Assignee Title
CN103563139A (zh) * 2011-05-31 2014-02-05 丰田自动车株式会社 锂二次电池
CN111094188A (zh) * 2017-07-12 2020-05-01 住友金属矿山株式会社 金属复合氢氧化物及其制造方法、非水电解质二次电池用正极活性物质及其制造方法、以及使用其的非水电解质二次电池
CN109461926A (zh) * 2018-11-09 2019-03-12 烟台卓能锂电池有限公司 一种锂离子电池正极材料及其制备方法、正极和锂离子电池
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