WO2024197826A1 - 正极活性材料、及其制备方法、正极极片、二次电池和用电装置 - Google Patents

正极活性材料、及其制备方法、正极极片、二次电池和用电装置 Download PDF

Info

Publication number
WO2024197826A1
WO2024197826A1 PCT/CN2023/085514 CN2023085514W WO2024197826A1 WO 2024197826 A1 WO2024197826 A1 WO 2024197826A1 CN 2023085514 W CN2023085514 W CN 2023085514W WO 2024197826 A1 WO2024197826 A1 WO 2024197826A1
Authority
WO
WIPO (PCT)
Prior art keywords
positive electrode
active material
electrode active
battery
hollow structure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CN2023/085514
Other languages
English (en)
French (fr)
Inventor
云亮
孙信
吴李力
宋佩东
陈兴布
董苗苗
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Contemporary Amperex Technology Co Ltd
Original Assignee
Contemporary Amperex Technology Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Contemporary Amperex Technology Co Ltd filed Critical Contemporary Amperex Technology Co Ltd
Priority to EP23929411.9A priority Critical patent/EP4614617A4/en
Priority to CN202511932716.XA priority patent/CN121416492A/zh
Priority to CN202380044727.7A priority patent/CN119452483B/zh
Priority to PCT/CN2023/085514 priority patent/WO2024197826A1/zh
Publication of WO2024197826A1 publication Critical patent/WO2024197826A1/zh
Priority to US19/210,483 priority patent/US20250276913A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Complex oxides containing nickel and at least one other metal element
    • C01G53/42—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2
    • C01G53/44—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese
    • C01G53/50—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese of the type (MnO2)n-, e.g. Li(NixMn1-x)O2 or Li(MyNixMn1-x-y)O2
    • C01G53/502—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese of the type (MnO2)n-, e.g. Li(NixMn1-x)O2 or Li(MyNixMn1-x-y)O2 containing lithium and cobalt
    • C01G53/504—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese of the type (MnO2)n-, e.g. Li(NixMn1-x)O2 or Li(MyNixMn1-x-y)O2 containing lithium and cobalt with the molar ratio of nickel with respect to all the metals other than alkali metals higher than or equal to 0.5, e.g. Li(MzNixCoyMn1-x-y-z)O2 with x ≥ 0.5
    • C01G53/506—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese of the type (MnO2)n-, e.g. Li(NixMn1-x)O2 or Li(MyNixMn1-x-y)O2 containing lithium and cobalt with the molar ratio of nickel with respect to all the metals other than alkali metals higher than or equal to 0.5, e.g. Li(MzNixCoyMn1-x-y-z)O2 with x ≥ 0.5 with the molar ratio of nickel with respect to all the metals other than alkali metals higher than or equal to 0.8, e.g. Li(MzNixCoyMn1-x-y-z)O2 with x ≥ 0.8
    • 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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Complex oxides containing nickel and at least one other metal element
    • C01G53/42—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/50—Solid solutions
    • C01P2002/52—Solid solutions containing elements as dopants
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/03—Particle morphology depicted by an image obtained by SEM
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/30—Particle morphology extending in three dimensions
    • C01P2004/32—Spheres
    • C01P2004/34—Spheres hollow
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/14—Pore volume
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the technical field of secondary batteries, and in particular to a positive electrode active material, a preparation method thereof, a positive electrode sheet, a secondary battery and an electrical device.
  • Secondary batteries have the characteristics of high capacity and long life, so they are widely used in electronic devices such as mobile phones, laptops, battery cars, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools, etc. Due to the great progress made in secondary batteries, higher requirements are placed on the performance of secondary batteries.
  • materials such as positive electrode active materials in secondary batteries are usually optimized and improved.
  • Positive electrode active materials as carriers of metal ions and electrons in secondary batteries, play the role of energy storage and release, and have a non-negligible effect on the performance of secondary batteries.
  • the improved positive electrode active materials are applied to secondary batteries, the cycle performance and rate performance of the secondary batteries are still poor.
  • the present application is made in view of the above-mentioned problems, and its purpose is to provide a positive electrode active material, which has a hollow structure, and the inner diameter of the hollow structure is 0.3 ⁇ m-5 ⁇ m, which can effectively improve the cycle performance of the battery, and the battery has excellent rate performance.
  • the first aspect of the present application provides a positive electrode active material, the chemical formula of the positive electrode active material is Li a Ni x Co y M 1-xy O 2 ,
  • M includes one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg, and Nb, 0.55 ⁇ x ⁇ 1.0, 0 ⁇ y ⁇ 0.45, 0.8 ⁇ a ⁇ 1.2, and the positive electrode active material has a hollow structure, and the inner diameter d1 of the hollow structure is 0.3 ⁇ m-5 ⁇ m.
  • the volume change of the positive electrode active material during the charge and discharge process can be buffered, which plays a role in stabilizing the structure and improving the cycle performance.
  • the positive electrode active material with a hollow structure has more three-dimensional channels, which expands the contact area between the material and the electrolyte, shortens the migration distance of lithium ions, reduces the internal resistance of the battery, and the battery has excellent rate performance.
  • the positive electrode active material with a hollow structure has more active sites for lithium ions, which increases the gram capacity of the material and improves the discharge capacity and energy density of the material.
  • the inner diameter d1 of the hollow structure is 1.5 ⁇ m-5 ⁇ m, which can further shorten the migration distance of lithium ions and improve the rate performance of the battery.
  • the positive electrode active material satisfies the following relationship: 1 ⁇ Dv50/(d1+d2) ⁇ 4,
  • d1 ⁇ m is the inner diameter of the hollow structure
  • d2 ⁇ m is the outer wall thickness of the hollow structure
  • Dv50 ⁇ m is the Dv50 of the positive electrode active material
  • the energy density of the battery can be increased and the rate performance of the battery can be improved.
  • the thickness d2 of the outer wall of the hollow structure is 3 ⁇ m-10 ⁇ m, and can be 3 ⁇ m-7 ⁇ m.
  • the structural stability of the material can be improved, the battery has a high discharge capacity and energy density, excellent rate performance and cycle performance, and comprehensively improves the electrochemical performance of the battery.
  • the Dv50 of the positive electrode active material is 5 ⁇ m-15 ⁇ m, and optionally 8 ⁇ m-10 ⁇ m.
  • Controlling the Dv50 of the positive electrode active material within an appropriate range can improve the energy density and rate performance of the battery.
  • the porosity of the positive electrode active material is 0-20%, and optionally 2%-15%.
  • the battery By controlling the porosity of the positive electrode active material within a suitable range, the battery has a high discharge capacity and energy density, excellent rate performance and cycle performance, and comprehensively improves the electrochemical performance of the battery.
  • the specific surface area of the positive electrode active material is 0.4 m 2 /g to 1.4 m 2 /g.
  • the battery By controlling the specific surface area of the positive electrode active material within a suitable range, the battery has a high discharge capacity and energy density, excellent rate performance and cycle performance, and comprehensively improves the electrochemical performance of the battery.
  • the SPAN of the positive electrode active material is 1-1.5, and optionally 1.2-1.4.
  • Controlling the SPAN of the positive electrode active material within an appropriate range can increase the discharge capacity of the battery.
  • the (010) crystal plane area of the positive electrode active material is greater than or equal to 6 ⁇ m 2 .
  • the battery By controlling the (010) crystal plane area of the positive electrode active material to be greater than or equal to 6 ⁇ m 2 , the battery has a high discharge capacity and energy density, excellent rate performance and cycle performance, and comprehensively improves the electrochemical performance of the battery.
  • the primary particle size of the positive electrode active material is 0.1-0.8 ⁇ m, and optionally 0.15-0.3 ⁇ m.
  • Controlling the primary particle size of the positive electrode active material within an appropriate range can increase the discharge capacity and energy density of the battery and improve the rate performance of the battery.
  • the second aspect of the present application provides a method for preparing a positive electrode active material, comprising steps (1) and (2):
  • Step (1) Mixing a mixed source including a nickel source and a cobalt source with a hard template, a complexing agent, and a precipitant to perform a coprecipitation reaction to obtain a precursor.
  • the mixed source contains an M source.
  • Step (2) calcining the precursor and the lithium source to obtain the positive electrode active material
  • the chemical formula of the positive electrode active material is Li a Ni x Co y M 1-xy O 2 ,
  • M includes Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg, Nb
  • Mn 0.55 ⁇ x ⁇ 1.0, 0 ⁇ y ⁇ 0.45, 0.8 ⁇ a ⁇ 1.2
  • the positive electrode active material is a hollow structure, and the inner diameter of the hollow structure is 0.3 ⁇ m to 5 ⁇ m.
  • a layer of tight nickel-cobalt hydroxide is coated on the surface of the hard template by coprecipitation reaction to form a compact core-shell structure, and the hard template is subsequently removed by calcination to obtain a positive electrode active material with a hollow structure.
  • the preparation method of the above positive electrode active material is simple and the production cost is low.
  • the prepared positive electrode active material has a hollow structure with an inner diameter of 0.3 ⁇ m to 5 ⁇ m, which is conducive to the insertion and removal of lithium ions.
  • the hollow structure can buffer the volume change of the positive electrode active material during the charge and discharge process, stabilize the structure and improve the cycle performance.
  • the average diameter of the hard template is 0.2 ⁇ m to 3 ⁇ m, and optionally 1 ⁇ m to 3 ⁇ m.
  • Controlling the average diameter of the hard template within a suitable range, and then controlling the inner diameter of the hollow structure of the positive electrode active material within a suitable range, can take into account both the diffusion path of lithium ions and the stability of the hollow structure, and comprehensively improve the cycle performance and rate performance of the battery.
  • the hard template includes one or more of carbon-nitrogen composite balls, carbon balls, phenolic resin microballs, and melamine resin microballs, and optionally includes phenolic resin balls.
  • the ratio of the weight of the hard template added in step (1) to the total weight of the nickel element and the cobalt element in the mixed source is 1:20-3:4.
  • the ratio of the weight of the hard template added in step (1) to the total weight of the nickel element, the cobalt element and the M element in the mixed source is 1:20-3:4.
  • the total weight of the hard template and the nickel element, cobalt element and/or M element in the mixed source is controlled within a suitable range, so that the nickel cobalt hydroxide layer is stably and evenly coated on the surface of the hard template, so that the hollow structure has a suitable inner diameter and outer wall thickness, the positive electrode active material has excellent structural properties, and the cycle performance and rate performance of the battery are improved.
  • the pH value of the coprecipitation reaction in step (1) is 9-13.
  • the appropriate pH value of the coprecipitation reaction makes the coprecipitation reaction more stable and efficient, so that the nickel-cobalt hydroxide layer is stably and evenly coated on the surface of the hard template, so that the hollow structure has a suitable inner diameter and outer wall thickness, and the positive electrode active material has excellent structural It can improve the cycle performance and rate performance of the battery.
  • the reaction temperature of the co-precipitation reaction in step (1) is 60-85°C.
  • the appropriate co-precipitation reaction temperature makes the co-precipitation reaction smoother and more efficient, so that the nickel-cobalt hydroxide layer is stably and evenly coated on the surface of the hard template, so that the hollow structure has a suitable inner diameter and outer wall thickness, and the positive electrode active material has excellent structural properties, thereby improving the cycle performance and rate performance of the battery.
  • reaction time of the co-precipitation reaction in step (1) is 5-20 hours.
  • the appropriate reaction time of the coprecipitation reaction makes the coprecipitation reaction smoother and more efficient, so that the nickel cobalt hydroxide layer is stably and evenly coated on the surface of the hard template, so that the hollow structure has a suitable inner diameter and outer wall thickness, and the positive electrode active material has excellent structural properties, thereby improving the cycle performance and rate performance of the battery.
  • the stirring speed of the co-precipitation reaction in step (1) is 200-900 rpm.
  • the appropriate stirring speed of the coprecipitation reaction makes the coprecipitation reaction smoother and more efficient, so that the nickel-cobalt hydroxide layer is stably and evenly coated on the surface of the hard template, so that the hollow structure has a suitable inner diameter and outer wall thickness, and the positive electrode active material has excellent structural properties, thereby improving the cycle performance and rate performance of the battery.
  • step (1) specifically comprises:
  • a hard template solution with a mass concentration of 1-10g/L, a precipitant solution with a molar concentration of 1-2mol/L, a complexing agent solution with a molar concentration of 4-8mol/L, and a mixed salt solution containing nickel and cobalt elements with a total molar concentration of 1-2mol/L, wherein the mixed salt solution may further contain M element;
  • a coprecipitation reaction is carried out to obtain a precursor.
  • the coprecipitation reaction is more stable and efficient, and during the coprecipitation reaction, nickel cobalt hydroxide It can be precipitated more slowly, stably and densely on the surface of the hard template, forming a more uniform shell structure on the surface of the hard template, so that the hollow structure has a suitable inner diameter, outer wall thickness and Dv50, and the positive electrode active material has excellent structural properties, thereby improving the cycle performance and rate performance of the battery.
  • the calcination temperature in step (2) is 700-900°C;
  • the calcination time in step (2) is 6-18h.
  • the calcination temperature and time are controlled within an appropriate range to ensure that the hard template can be completely removed to form a hollow structure. At the same time, the stability of the positive electrode active material structure must be ensured.
  • the positive electrode active material has a stable hollow structure to improve the battery's cycle performance and rate performance.
  • a third aspect of the present application provides a positive electrode plate, which includes the positive electrode active material of the first aspect or the positive electrode active material prepared by the preparation method of the second aspect.
  • a fourth aspect of the present application provides a secondary battery, comprising the positive electrode sheet of the third aspect.
  • a fifth aspect of the present application provides an electrical device, comprising the secondary battery of the fourth aspect.
  • FIG1 is a scanning electron microscope image of the positive electrode active material shown in Example 4 of the present application.
  • FIG2 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG3 is an exploded view of the secondary battery of one embodiment of the present application shown in FIG2 ;
  • FIG4 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG5 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG6 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG5 ;
  • FIG. 7 is a schematic diagram of an electrical device using a secondary battery as a power source according to an embodiment of the present application.
  • “Scope” disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited 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 limited in this way can be including end values or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. 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" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an 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 also 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), may also include steps (a), (c) and (b), may also 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).
  • nickel-rich ternary materials have become one of the popular secondary battery positive electrode active materials due to their high theoretical specific capacity, high discharge platform, and low cost.
  • the similar ion radius of Ni +2 and Li + in ternary materials will cause serious cation mixing, which will cause the electrochemical performance of the material to decline.
  • the cation mixing trend increases and the battery cycle performance deteriorates.
  • the present application proposes a positive electrode active material, the chemical formula of the positive electrode active material is Li a Ni x Co y M 1-xy O 2 ,
  • M includes one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg, and Nb, 0.55 ⁇ x ⁇ 1.0, 0 ⁇ y ⁇ 0.45, 0.8 ⁇ a ⁇ 1.2, and the positive electrode active material has a hollow structure, and the inner diameter d1 of the hollow structure is 0.3 ⁇ m-5 ⁇ m.
  • the term “hollow structure” refers to a solid structure having an internal cavity surrounded by a distinct shell.
  • inner diameter of the hollow structure refers to the longest diameter of a circular or quasi-circular cross-section of the inner cavity of the positive electrode active material.
  • the inner diameter of the hollow structure can be tested by any means known in the art.
  • a conductive glue is pasted on the sample table, a powdered sample of the positive electrode active material is spread on the conductive glue, the unadhered powder is blown away with an ear bulb, gold is sprayed, and the particles of the powdered sample are cross-sectioned using argon plasma.
  • a scanning electron microscope is used to obtain a scanning electron microscope photo of the powdered sample under the conditions of an acceleration voltage of 10kV and an emission current of 10mA. According to the scanning electron microscope photo, the inner diameter of the hollow structure is measured, at least three samples are measured, at least 50 data are measured for each sample, and the number average is taken as the inner diameter of the hollow structure of the sample.
  • a is any value selected from 0.8, 0.9, 1.0 , 1.1, 1.2, or a range consisting of any two of these values.
  • x is any value selected from 0.55, 0.6 , 0.7, 0.8, 0.9, 0.95 , 0.995, or a range consisting of any two of these values.
  • y is any value selected from 0, 0.1, 0.2, 0.3 , 0.4 , 0.45, or a range consisting of any two values thereof.
  • LiaNixCoyM1 -xyO2 0.90 ⁇ x ⁇ 1.0 , 0 ⁇ y ⁇ 0.1, and 0.8 ⁇ a ⁇ 1.2.
  • LiaNixCoyM1 -xyO2 0.95 ⁇ x ⁇ 0.995, 0 ⁇ y ⁇ 0.05, and 0.8 ⁇ a ⁇ 1.2 .
  • the positive electrode active material has a chemical formula of LiaNixCoyMn1 -x -yO2 , 0.95 ⁇ x ⁇ 0.995, 0 ⁇ y ⁇ 0.05 , 0.8 ⁇ a ⁇ 1.2 .
  • the chemical formula of the positive electrode active material is LiaNixCoySb1 -xyO2 , 0.95 ⁇ x ⁇ 0.995, 0 ⁇ y ⁇ 0.05, 0.8 ⁇ a ⁇ 1.2 .
  • the use of the above materials can ensure that the positive electrode active material has a high gram capacity, so that the battery has a high discharge capacity and energy density.
  • the inner diameter d1 of the hollow structure may be 0.3 ⁇ m-0.5 ⁇ m. Any one of 0.3 ⁇ m-0.9 ⁇ m, 0.3 ⁇ m-1 ⁇ m, 0.3 ⁇ m-2 ⁇ m, 0.3 ⁇ m-3 ⁇ m, 0.3 ⁇ m-4 ⁇ m, 0.3 ⁇ m-5 ⁇ m, 1 ⁇ m-2 ⁇ m, 1 ⁇ m-3 ⁇ m, 1 ⁇ m-4 ⁇ m, 1 ⁇ m-5 ⁇ m, 2 ⁇ m-3 ⁇ m, 2 ⁇ m-4 ⁇ m, 2 ⁇ m-5 ⁇ m, 3 ⁇ m-4 ⁇ m, 3 ⁇ m-5 ⁇ m, 4 ⁇ m-5 ⁇ m.
  • the volume change of the positive electrode active material during the charge and discharge process can be buffered, which plays a role in stabilizing the structure and improving the cycle performance.
  • the positive electrode active material with a hollow structure has more three-dimensional channels, which expands the contact area between the material and the electrolyte, shortens the migration distance of lithium ions, reduces the internal resistance of the battery, and the battery has excellent rate performance.
  • the positive electrode active material with a hollow structure has more active sites for lithium ions, which increases the gram capacity of the material and improves the discharge capacity and energy density of the material.
  • the inner diameter d1 of the hollow structure is 1.5 ⁇ m-5 ⁇ m. In some embodiments, the inner diameter d1 of the hollow structure can be any one of 1.5 ⁇ m-3 ⁇ m, 2 ⁇ m-4 ⁇ m, 2 ⁇ m-5 ⁇ m, 3 ⁇ m-4 ⁇ m, 3 ⁇ m-5 ⁇ m, and 4 ⁇ m-5 ⁇ m.
  • the migration distance of lithium ions can be further shortened and the rate performance of the battery can be improved.
  • the positive electrode active material satisfies the following relationship: 1 ⁇ Dv50/(d1+d2) ⁇ 4,
  • d1 ⁇ m is the inner diameter of the hollow structure
  • d2 ⁇ m is the outer wall thickness of the hollow structure
  • Dv50 ⁇ m is the Dv50 of the positive electrode active material
  • the positive electrode active material satisfies any one of the following relationships: 1 ⁇ Dv50/(d1+d2) ⁇ 2, 1 ⁇ Dv50/(d1+d2) ⁇ 3, 1 ⁇ Dv50/(d1+d2) ⁇ 4, 2 ⁇ Dv50/(d1+d2) ⁇ 3, 2 ⁇ Dv50/(d1+d2) ⁇ 4, 3 ⁇ Dv50/(d1+d2) ⁇ 4,
  • d1 ⁇ m is the inner diameter of the hollow structure
  • d2 ⁇ m is the outer wall thickness of the hollow structure
  • Dv50 ⁇ m is the Dv50 of the positive electrode active material
  • outer wall thickness of the hollow structure refers to the thickness of the outer shell of the hollow structure.
  • the thickness of the outer wall of the hollow structure can be tested by any means known in the art.
  • a conductive glue is pasted on the sample table, a powdered sample of the positive electrode active material is spread flat on the conductive glue, an ear-cleaning bulb is used to blow away the unadhered powder, gold is sprayed, and the particles of the powdered sample are cross-sectioned using argon plasma.
  • a scanning electron microscope is used to obtain a scanning electron microscope photo of the powdered sample under the conditions of an acceleration voltage of 10 kV and an emission current of 10 mA.
  • the outer wall thickness of the hollow structure is measured based on the scanning electron microscope photo, at least three samples are measured, at least 50 data are measured for each sample, and the number average value is taken as the outer wall thickness of the hollow structure of the sample.
  • Dv50 refers to the median particle size of the positive electrode active material. Specifically, Dv50 represents a particle size that reaches 50% of the volume accumulation from the small particle size side in the volume-based particle size distribution of the positive electrode active material.
  • the Dv50 of the positive electrode active material can be tested by any means known in the art.
  • the Dv50 value of the positive electrode active material can be measured by referring to the method specified in GB/T19077-2016.
  • the Dv50 of the positive electrode active material, the inner diameter d1 of the hollow structure and the outer wall thickness d2 are important parameters of the positive electrode active material structure, which affect the structural performance of the material.
  • the material has more active sites for lithium ions, which increases the material's gram capacity, thereby increasing the material's battery density.
  • the structural stability of the material can be improved, the lithium-nickel mixing phenomenon is effectively improved, the migration rate of lithium ions and electrons is significantly increased, and the rate performance of the material is improved.
  • the energy density of the battery can be increased and the rate performance of the battery can be improved.
  • the thickness d2 of the outer wall of the hollow structure is 3 ⁇ m-10 ⁇ m.
  • the outer wall thickness d2 of the hollow structure can be selected from 3 ⁇ m-4 ⁇ m, 3 ⁇ m-5 ⁇ m, 3 ⁇ m-6 ⁇ m, 3 ⁇ m-7 ⁇ m, 3 ⁇ m-8 ⁇ m, 3 ⁇ m-9 ⁇ m, 3 ⁇ m-10 ⁇ m, 4 ⁇ m-5 ⁇ m, 4 ⁇ m-6 ⁇ m, 4 ⁇ m-7 ⁇ m, 4 ⁇ m-8 ⁇ m, 4 ⁇ m-9 ⁇ m, 4 ⁇ m-10 ⁇ m, 5 ⁇ m-6 ⁇ m, 5 ⁇ m-7 ⁇ m, 5 ⁇ m-8 ⁇ m, 5 ⁇ m-9 ⁇ m, 5 ⁇ m-10 ⁇ m, 6 ⁇ m-7 ⁇ m, 6 ⁇ m-8 ⁇ m, 6 ⁇ m-9 ⁇ m, 6 ⁇ m-10 ⁇ m, 7 ⁇ m-8 ⁇ m, 7 ⁇ m-9 ⁇ m, 7 ⁇ m-10 ⁇ m, 8 ⁇ m-9 ⁇ m, 8 ⁇ m-10 ⁇ m, 9 ⁇ m-10 ⁇ m. Either one.
  • the structural stability of the material can be improved, the battery has a high discharge capacity and energy density, excellent rate performance and cycle performance, and comprehensively improves the electrochemical performance of the battery.
  • the outer wall thickness d2 of the hollow structure is 3 ⁇ m-7 ⁇ m. In some embodiments, the outer wall thickness d2 of the hollow structure can be selected from any one of 3 ⁇ m-4 ⁇ m, 3 ⁇ m-5 ⁇ m, 3 ⁇ m-6 ⁇ m, 3 ⁇ m-7 ⁇ m, 4 ⁇ m-5 ⁇ m, 4 ⁇ m-6 ⁇ m, 4 ⁇ m-7 ⁇ m, 5 ⁇ m-6 ⁇ m, 5 ⁇ m-7 ⁇ m, and 6 ⁇ m-7 ⁇ m.
  • the cycle performance and rate performance of the battery can be further improved.
  • the Dv50 of the positive electrode active material is 5 ⁇ m-15 ⁇ m. In some embodiments, the Dv50 of the positive electrode active material is any one of 5 ⁇ m-9 ⁇ m, 5 ⁇ m-10 ⁇ m, 5 ⁇ m-15 ⁇ m, 9 ⁇ m-10 ⁇ m, 9 ⁇ m-15 ⁇ m, and 10 ⁇ m-15 ⁇ m.
  • Particles of different sizes have different areas and different numbers of reactive sites. Therefore, the size of the particles will affect the speed of ion embedding and deintercalation, and the gram capacity of the material. Controlling the Dv50 of the positive electrode active material within an appropriate range can improve the energy density and rate performance of the battery.
  • the Dv50 of the positive electrode active material is 8 ⁇ m-10 ⁇ m. In some embodiments, the Dv50 of the positive electrode active material is any one of 8 ⁇ m-9 ⁇ m, 8 ⁇ m-10 ⁇ m, and 9 ⁇ m-10 ⁇ m.
  • Controlling the Dv50 of the positive electrode active material within an appropriate range can further improve the energy density and rate performance of the battery.
  • the porosity of the positive electrode active material is 0-20%. In some embodiments, the porosity of the positive electrode active material can be selected from any one of 0-5%, 0-10%, 0-15%, 0-20%, 5-10%, 5-15%, 5-20%, 10-15%, 10-20%, and 15-20%.
  • porosity refers to the ratio of the volume of pores in the positive electrode active material to the total volume of the positive electrode active material.
  • Controlling the porosity of the positive electrode active material within an appropriate range is beneficial to the infiltration of the electrolyte, allowing the positive electrode active material to fully contact the electrolyte, shortening the lithium ion transmission path, and allowing the battery to have a high discharge capacity and energy density, excellent rate performance and cycle performance, and comprehensively improving the electrochemical performance of the battery.
  • the porosity of the positive electrode active material is 2-15%. In some embodiments, the porosity of the positive electrode active material can be any one of 2-5%, 2-10%, 2-15%, 5-10%, 5-15%, and 10-15%.
  • Controlling the porosity of the positive electrode active material within an appropriate range can further increase the discharge capacity and energy density of the battery and improve the rate performance and cycle performance of the battery.
  • the specific surface area of the positive electrode active material is 0.4m2 / g- 1.4m2 /g. In some embodiments, the specific surface area of the positive electrode active material can be selected from any one of 0.4m2 / g-0.7m2 / g , 0.4m2/ g -0.9m2/g , 0.5m2/g-0.7m2/g, 0.5m2/g-0.9m2/g, 0.5m2 / g-1.1m2 /g , 0.7m2/g - 0.9m2 / g , 0.7m2 / g - 1.1m2/g, and 0.9m2/g - 1.1m2 /g.
  • the specific surface area of the positive electrode active material can be tested by any means known in the art. As an example, reference can be made to GB/T 19587-2017 "Gas Adsorption BET Method for Determination of Specific Surface Area of Solids".
  • the TriStar II 3020 device is used for the measurement.
  • the positive electrode active material is dispersed in a dispersant (ethanol). After ultrasonic treatment for 30 minutes, the obtained material is placed in a vacuum drying oven for drying. Finally, the specific surface area of the positive electrode active material is measured using a specific surface area tester.
  • the battery By controlling the specific surface area of the positive electrode active material within a suitable range, the battery has a high discharge The battery has high capacity and energy density, excellent rate performance and cycle performance, and comprehensively improves the electrochemical performance of the battery.
  • the SPAN of the positive electrode active material is 1-1.5. In some embodiments, the SPAN of the positive electrode active material can be selected from any one of 1-1.1, 1-1.2, 1-1.3, 1-1.4, 1-1.5, 1.1-1.2, 1.1-1.3, 1.1-1.4, 1.1-1.5, 1.2-1.3, 1.2-1.4, 1.2-1.5, 1.3-1.4, 1.3-1.5, 1.4-1.5.
  • the term “SPAN” refers to distribution span, which is calculated as (Dv90-Dv10)/Dv50, and represents the particle distribution of the positive electrode active material, wherein Dv50 represents the particle size of the positive electrode active material in the volume-based particle size distribution, from the small particle size side to the volume cumulative 50%; Dv10 represents the particle size of the positive electrode active material in the volume-based particle size distribution, from the small particle size side to the volume cumulative 10%; and Dv90 represents the particle size of the positive electrode active material in the volume-based particle size distribution, from the small particle size side to the volume cumulative 90%.
  • the Dv50, Dv10, and Dv90 values of the positive electrode active material were measured according to the method specified in GB/T19077-2016, and the SPAN of the positive electrode active material was then calculated.
  • Maintaining SPAN in a wider range can increase the compaction density of the material and improve the discharge capacity of the battery.
  • the SPAN of the positive electrode active material is 1.2-1.4. In some embodiments, the SPAN of the positive electrode active material can be selected from any one of 1.2-1.3, 1.2-1.4, 1.3-1.4, etc.
  • SPAN is maintained in a wide range, with particles of different sizes, which avoids the cracking of particles during battery cycling and makes the battery have excellent cycle performance; the synthesized precursor particles are uneven in size and the particles are in close contact with each other, which improves the transmission speed of lithium ions and makes the battery have excellent rate performance.
  • the cycle performance and rate performance of the battery can be taken into account, and the electrochemical performance of the battery can be comprehensively improved.
  • the (010) crystal plane area of the positive electrode active material is greater than or equal to 6 ⁇ m 2 .
  • the (010) crystal plane area of the positive electrode active material is greater than or equal to Any one of 6 ⁇ m 2 , 20 ⁇ m 2 , 50 ⁇ m 2 , 100 ⁇ m 2 , 150 ⁇ m 2 , 200 ⁇ m 2 , 240 ⁇ m 2 , and 250 ⁇ m 2 .
  • the (010) crystal plane area of the positive electrode active material can be tested by any means known in the art.
  • an X-ray powder diffractometer (XRD, instrument model: Bruker D8ADVANCE) is used to test the (101) crystal plane area, the target material is Cu K ⁇ ; the voltage and current are 40KV/40mA, the scanning angle range is 5° to 80°, the scanning step length is 0.00836°, and the time per step is 0.3s.
  • the (010) crystal plane is the dominant plane for lithium ion transmission.
  • the positive electrode active material has a large (010) crystal plane area, the positive electrode active material has a large number of lithium ion reaction active sites, and the battery has excellent kinetic performance.
  • the battery By controlling the (010) crystal plane area of the positive electrode active material to be greater than or equal to 6 ⁇ m 2 , the battery has a high discharge capacity and energy density, excellent rate performance and cycle performance, and comprehensively improves the electrochemical performance of the battery.
  • the primary particle size of the positive electrode active material is 0.1-0.8 ⁇ m.
  • the primary particle size of the positive electrode active material can be selected from 0.1-0.2 ⁇ m, 0.1-0.3 ⁇ m, 0.1-0.4 ⁇ m, 0.1-0.5 ⁇ m, 0.1-0.6 ⁇ m, 0.1-0.7 ⁇ m, 0.1-0.8 ⁇ m, 0.2-0.3 ⁇ m, 0.2-0.4 ⁇ m, 0.2-0.5 ⁇ m, 0.2-0.6 ⁇ m, 0.2-0.7 ⁇ m, 0.2-0.8 ⁇ m, Any one of 0.3-0.4 ⁇ m, 0.3-0.5 ⁇ m, 0.3-0.6 ⁇ m, 0.3-0.7 ⁇ m, 0.3-0.8 ⁇ m, 0.4-0.5 ⁇ m, 0.4-0.6 ⁇ m, 0.4-0.7 ⁇ m, 0.4-0.8 ⁇ m, 0.5-0.6 ⁇ m, 0.5-0.7 ⁇ m, 0.5-0.8 ⁇ m, 0.6-0.7 ⁇ m, 0.6-0.8 ⁇ m, 0.7-0.8 ⁇ m.
  • primary particles refers to particles of the positive electrode active material before agglomeration.
  • the primary particle size of the positive electrode active material can be tested by any means known in the art. As an example, after imaging by a 500-fold scanning electron microscope, 200 to 600 primary particles of the positive electrode active material with complete shapes and no obstructions are randomly selected from the electron microscopic image, and the average value of the longest diameter of the primary particles in the microscopic image is recorded as the average particle size.
  • Control the primary particle size of the positive electrode active material within an appropriate range to shorten the lithium ion Diffusion paths can speed up the insertion and extraction rates of lithium ions, thereby increasing the discharge capacity and energy density of the battery and improving the battery's rate performance.
  • the primary particle size of the positive electrode active material is 0.15-0.3 ⁇ m. In some embodiments, the primary particle size of the positive electrode active material can be any one of 0.15-0.2 ⁇ m, 0.15-0.3 ⁇ m, and 0.2-0.3 ⁇ m.
  • the particle size of the primary particles of the positive electrode active material is controlled within an appropriate range, and the primary particles have excellent structural stability.
  • the primary particles can still maintain their complete structure, reducing the phenomenon of transition metals inside the primary particles escaping from the primary particles and dissolving into the electrolyte, thereby improving the cycle stability of the battery.
  • the gram capacity of the positive electrode active material is 238 mAh/g-250 mAh/g.
  • the gram capacity of the positive electrode active material can be tested by any means known in the art. As an example, at 25°C and normal pressure, charge the button cell at a constant current rate of 0.02C to a voltage of 3.5V, then charge at a constant current rate of 0.1C to a voltage of 4.3V, and then charge at a constant voltage of 4.3V until the current drops to 0.05C. Record the charge specific capacity at this time, which is the first lithium removal capacity; then discharge at a constant current rate of 0.1C to a voltage of 2.5V, and record the discharge specific capacity at this time, which is the first lithium insertion capacity.
  • the gram capacity of the positive electrode active material is the first lithium insertion capacity.
  • the present application also proposes a method for preparing a positive electrode active material, comprising steps (1) and (2):
  • Step (1) Mixing a mixed source including a nickel source and a cobalt source with a hard template, a complexing agent, and a precipitant to perform a coprecipitation reaction to obtain a precursor.
  • the mixed source contains an M source.
  • Step (2) calcining the precursor and the lithium source to obtain the positive electrode active material
  • the chemical formula of the positive electrode active material is Li a Ni x Co y M 1-xy O 2 ,
  • M includes one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg, and Nb, 0.55 ⁇ x ⁇ 1.0, 0 ⁇ y ⁇ 0.45, 0.8 ⁇ a ⁇ 1.2, and the positive electrode active material has a hollow structure with an inner diameter of 0.3 ⁇ m to 5 ⁇ m.
  • co-precipitation reaction refers to a precipitation reaction in which a metal solution, a precipitant, and a complexing agent are reacted together at a certain temperature.
  • the M source is a manganese source or an antimony source.
  • the method for preparing a positive electrode active material comprises steps (1) and (2):
  • Step (1) Mixing a mixed source including a nickel source and a cobalt source with a hard template, a complexing agent, and a precipitant to perform a coprecipitation reaction to obtain a precursor.
  • Step (2) calcining the precursor and the lithium source to obtain the positive electrode active material.
  • the nickel source includes one or more of nickel sulfate, nickel hydrochloride, nickel nitrate, and nickel acetate.
  • the cobalt source includes one or more of cobalt sulfate, cobalt hydrochloride, cobalt nitrate, and cobalt acetate.
  • the manganese source includes one or more of manganese sulfate, manganese hydrochloride, manganese nitrate, and manganese acetate.
  • the antimony source includes one or more of antimony sulfate, antimony hydrochloride, antimony nitrate, and antimony acetate.
  • a layer of tight nickel-cobalt hydroxide is coated on the surface of the hard template by coprecipitation reaction to form a compact core-shell structure, and the hard template is subsequently removed by calcination to obtain a positive electrode active material with a hollow structure.
  • the preparation method of the above positive electrode active material is simple and the production cost is low.
  • the prepared positive electrode active material has a hollow structure with an inner diameter of 0.3 ⁇ m to 5 ⁇ m, which is conducive to the insertion and removal of lithium ions.
  • the hollow structure can buffer the volume change of the positive electrode active material during the charge and discharge process, stabilize the structure and improve the cycle performance.
  • the average diameter of the hard template is 0.2 ⁇ m-3 ⁇ m. In some embodiments, the average diameter of the hard template can be any one of 0.2 ⁇ m-1 ⁇ m, 0.2 ⁇ m-2 ⁇ m, 0.2 ⁇ m-3 ⁇ m, 1 ⁇ m-2 ⁇ m, 1 ⁇ m-3 ⁇ m, and 2 ⁇ m-3 ⁇ m.
  • the average diameter of the hard template is 1 ⁇ m-3 ⁇ m. In some embodiments, the average diameter of the hard template can be any one of 1 ⁇ m-2 ⁇ m, 1 ⁇ m-3 ⁇ m, and 2 ⁇ m-3 ⁇ m.
  • Controlling the average diameter of the hard template within a suitable range, and then controlling the inner diameter of the hollow structure of the positive electrode active material within a suitable range, can take into account both the diffusion path of lithium ions and the stability of the hollow structure, and comprehensively improve the cycle performance and rate performance of the battery.
  • the hard template includes one or more of carbon-nitrogen composite spheres, carbon spheres, phenolic resin microspheres, and melamine resin microspheres.
  • the hard templating agent comprises phenolic resin spheres.
  • the suitable hard template has excellent adsorption, so that in the coprecipitation reaction, a dense layer of nickel-cobalt hydroxide can be formed on the surface of the hard template, and the positive electrode active material has excellent structural properties, which improves the cycle performance and rate performance of the battery.
  • the ratio of the weight of the hard template added in step (1) to the total weight of the nickel element and the cobalt element in the mixed source is 1:20-3:4.
  • the ratio of the weight of the hard template added in step (1) to the total weight of the nickel element, the cobalt element and the M element in the mixed source is 1:20-3:4.
  • the ratio of the weight of the hard template added in step (1) to the total weight of the nickel element and the cobalt element in the mixed source is any value of 1:20, 1:15, 1:10, 1:5, 1:4, 2:4, 3:4 or a range consisting of any two values thereof.
  • the ratio of the weight of the hard template added in step (1) to the total weight of the nickel element, the cobalt element and the M element in the mixed source is any value of 1:20, 1:15, 1:10, 1:5, 1:4, 2:4, 3:4 or a range consisting of any two values thereof.
  • the ratio of the weight of the hard template added in step (1) to the total weight of nickel, cobalt and manganese in the mixed source is any value of 1:20, 1:15, 1:10, 1:5, 1:4, 2:4, 3:4 or a range consisting of any two of them.
  • the total weight of the hard template and the nickel element, cobalt element and/or M element in the mixed source is controlled within a suitable range, so that the nickel cobalt hydroxide layer is stably and evenly coated on the surface of the hard template, so that the hollow structure has a suitable inner diameter and outer wall thickness, the positive electrode active material has excellent structural properties, and the cycle performance and rate performance of the battery are improved.
  • the pH value of the coprecipitation reaction in step (1) is 9-13.
  • the pH value is any of 9, 10, 11, 12, 13, or a range consisting of any two of these values.
  • the appropriate pH value of the coprecipitation reaction makes the coprecipitation reaction smoother and more efficient, so that the nickel cobalt hydroxide layer is stably and evenly coated on the surface of the hard template, so that the hollow structure has a suitable inner diameter and outer wall thickness, and the positive electrode active material has excellent structural properties, thereby improving the cycle performance and rate performance of the battery.
  • the reaction temperature of the co-precipitation reaction in step (1) is 60-85°C.
  • the reaction temperature is any value of 60°C, 70°C, 80°C, 85°C, or a range consisting of any two values thereof.
  • the appropriate co-precipitation reaction temperature makes the co-precipitation reaction smoother and more efficient, so that the nickel-cobalt hydroxide layer is stably and evenly coated on the surface of the hard template, so that the hollow structure has a suitable inner diameter and outer wall thickness, and the positive electrode active material has excellent structural properties, thereby improving the cycle performance and rate performance of the battery.
  • the reaction time of the co-precipitation reaction in step (1) is 5-20 hours.
  • reaction time is any value of 5 h, 10 h, 15 h, 20 h, or a range consisting of any two values thereof.
  • the appropriate reaction time of the coprecipitation reaction makes the coprecipitation reaction smoother and more efficient, so that the nickel cobalt hydroxide layer is stably and evenly coated on the surface of the hard template, so that the hollow structure has a suitable inner diameter and outer wall thickness, and the positive electrode active material has excellent structural properties, thereby improving the cycle performance and rate performance of the battery.
  • the stirring speed of the co-precipitation reaction in step (1) is 200-900 rpm.
  • the reaction stirring speed is any value of 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, or a range consisting of any two values thereof.
  • the appropriate stirring speed of the coprecipitation reaction makes the coprecipitation reaction more stable and efficient.
  • the nickel-cobalt hydroxide layer is stably and evenly coated on the surface of the hard template, so that the hollow structure has a suitable inner diameter and outer wall thickness, the positive electrode active material has excellent structural properties, and the cycle performance and rate performance of the battery are improved.
  • step (1) specifically includes:
  • a hard template solution with a mass concentration of 1-10g/L, a precipitant solution with a molar concentration of 1-2mol/L, a complexing agent solution with a molar concentration of 4-8mol/L, and a mixed salt solution containing nickel and cobalt elements with a total molar concentration of 1-2mol/L, wherein the mixed salt solution may further contain M element;
  • a coprecipitation reaction is carried out to obtain a precursor.
  • the precipitating agent includes one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonium bicarbonate, and optionally ammonium bicarbonate.
  • the complexing agent includes one or more of ammonia water, lactic acid, polyvinyl pyrrolidone, and can be ammonia water.
  • the mass concentration of the hard template solution is any value of 1 g/L, 2 g/L, 3 g/L, 4 g/L, 5 g/L, 6 g/L, 7 g/L, 8 g/L, 9 g/L, 10 g/L, or a range consisting of any two values thereof.
  • the molar concentration of the precipitant solution is any value of 1 mol/L, 1.5 mol/L, 2 mol/L, or a range consisting of any two values thereof.
  • the molar concentration of the complexing agent solution is any value of 4 mol/L, 5 mol/L, 6 mol/L, 7 mol/L, 8 mol/L, or a range consisting of any two of these values.
  • the molar concentration of the mixed salt is any value of 1 mol/L, 1.5 mol/L, 2 mol/L, or a range consisting of any two values thereof.
  • the coprecipitation reaction is more stable and efficient.
  • nickel cobalt hydroxide can be more slowly, stably, and densely precipitated on the surface of the hard template, forming a more uniform shell structure on the surface of the hard template, so that the hollow structure has a suitable inner diameter, outer wall thickness, and Dv50, and the positive electrode active material has excellent structural properties, which improves the cycle performance and Rate performance.
  • the calcination temperature in step (2) is 700-900°C;
  • the calcination time in step (2) is 6-18h.
  • the calcination temperature in step (2) is any value of 700° C., 800° C., 900° C., or a range consisting of any two of these values.
  • the calcination time in step (2) is any value among 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, or a range consisting of any two values thereof.
  • the calcination temperature and time are controlled within an appropriate range to ensure that the hard template can be completely removed to form a hollow structure. At the same time, the stability of the positive electrode active material structure must be ensured.
  • the positive electrode active material has a stable hollow structure to improve the battery's cycle performance and rate performance.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer formed on at least a portion of the surface of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material in some embodiments.
  • the surface density of the positive electrode film layer is 24-46 mg/cm 2 .
  • the positive electrode film layer may further include a conductive agent to improve the conductivity of the positive electrode.
  • the conductive agent may be one or more of Super P, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphite, graphene and carbon nanofibers.
  • the positive electrode film layer may further include a binder to firmly bond the positive electrode active material and the optional conductive agent to the positive electrode current collector.
  • the binder may be selected from at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), polyvinyl alcohol (PVA), ethylene vinyl acetate copolymer (EVA), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), sodium alginate (SA), polymethacrylic acid (PMA) and carboxymethyl chitosan (CMCS).
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PAA polyacrylic acid
  • PVA polyvinyl alcohol
  • EVA ethylene vinyl acetate copolymer
  • SBR styrene butadiene rubber
  • CMC carboxymethyl cellulose
  • SA sodium alginate
  • PMA polymethacryl
  • the positive electrode current collector can be made of conductive carbon sheet, metal foil, carbon-coated metal foil, porous metal plate or composite current collector.
  • the conductive carbon material of the conductive carbon sheet can be Super P, carbon One or more of black, Ketjen black, carbon dots, carbon nanotubes, graphite, graphene and carbon nanofibers;
  • the metal materials of the metal foil, carbon-coated metal foil and porous metal plate are independently selected from at least one of copper, aluminum, nickel and stainless steel;
  • the composite current collector can be a composite current collector formed by a composite of a metal foil and a polymer base film.
  • the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active 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 includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector.
  • the negative electrode film layer includes 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 adopt the negative electrode material for the 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 materials for batteries may also be used. These negative electrode materials may be used alone or in combination of two or more.
  • the gram capacity of the negative electrode active material is 600 mAh/g to 2500 mAh/g.
  • the negative electrode active material includes silicon oxide.
  • the mass content of silicon oxide is 20%-100%, and optionally 50%-100%.
  • 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 film layer, such as the negative electrode 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 bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluoro(oxalatoborate), ... At least one of lithium oxalodifluorophosphate and lithium tetrafluorooxalodifluorophosphate.
  • 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.
  • the materials of each layer can be the same or different, without particular limitation.
  • 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, which may be used to encapsulate the electrode assembly and the electrolyte.
  • 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 outer packaging of the secondary battery may also be a soft package, such as a bag-type soft package.
  • the material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.
  • FIG. 2 is a square structure as an example. Secondary battery 5.
  • the energy density of the secondary battery is 380-500 Wh/Kg.
  • 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 secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • secondary batteries may be assembled into a battery module.
  • the number of secondary batteries 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.
  • FIG4 is a battery module 4 as an example.
  • a plurality of secondary batteries 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 secondary batteries 5 may be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space, and the plurality of secondary batteries 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.
  • FIG5 and FIG6 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 electrical device, the electrical device comprising at least one of the secondary battery, battery module, or battery pack provided in the present application.
  • the battery, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device.
  • the electrical 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 secondary battery, a battery module or a battery pack may be selected according to its usage requirements.
  • FIG7 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.
  • a battery pack or a battery module may be used.
  • the device may be a mobile phone, a tablet computer, a notebook computer, etc.
  • a device is usually required to be light and thin, and a secondary battery may be used as a power source.
  • a nickel-cobalt-manganese solution with a molar ratio of nickel, cobalt and manganese of 97:2:1, and adjust the concentration to 2 mol/L, wherein the raw materials of soluble nickel-cobalt-manganese are nickel sulfate, cobalt sulfate and manganese sulfate respectively; prepare a 2 mol/L sodium hydroxide solution; prepare a 6 mol/L ammonia solution; prepare a carbon ball dispersion with a mass concentration of 10 g/L, place it in a reactor, and stir at 800 rpm for 120 minutes until it is evenly dispersed. Carbon ball specifications: diameter 0.25 ⁇ m.
  • the nickel-cobalt-manganese solution, sodium hydroxide solution and ammonia solution are added to the reaction mixture at the same time.
  • the coprecipitation reaction was carried out in the kettle, with the speed controlled at 800 rpm, the temperature at 60°C, and the time at 6 hours.
  • the flow rates of the three solutions were adjusted, with the flow rate of the sodium hydroxide solution at 0.5 L/min, the flow rate of the ammonia solution at 0.7 L/min, and the flow rate of the nickel-cobalt-manganese solution at 0.2 L/min, and the pH of the system was controlled at 10.8.
  • the ratio of the weight of the carbon spheres to the total weight of nickel, cobalt, and manganese in the nickel-cobalt-manganese solution was 1:19.
  • reaction materials After the coprecipitation reaction is completed, the reaction materials overflow into the aging kettle, some washing additives are added, stirred for 1 hour, and then the materials are dehydrated, washed, dehydrated again, dried, screened, and demagnetized to obtain a positive electrode active material precursor with a carbon ball at the center.
  • the positive electrode active material precursor and lithium carbonate are uniformly mixed in a certain ratio, wherein the Li/Me molar ratio is 1.02; Me is the total molar content of nickel element, cobalt element and manganese element.
  • the uniformly mixed materials are placed in an oxygen atmosphere furnace, the heating rate is set to 5°C/min, and the temperature is kept at 705°C for 6 hours.
  • the atmosphere is required to have an oxygen content of ⁇ 98%, and then cooled with the furnace.
  • the material obtained after calcination is subjected to roller crushing, ultracentrifugal grinding and pulverization, and then sieved through a 400-mesh sieve to obtain the positive electrode active material.
  • the above-mentioned positive electrode active material, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) are added with N-methylpyrrolidone in a mass ratio of 97:1:2, and mixed and stirred for 3 hours to obtain a positive electrode slurry; then it is evenly coated on the positive electrode current collector aluminum foil, and dried, cold pressed, and cut to obtain a positive electrode sheet.
  • PVDF polyvinylidene fluoride
  • Artificial graphite doped with silicon oxide, conductive agent carbon black, carbon nanotubes (CNT), binder styrene-butadiene rubber (SBR), and thickener sodium hydroxymethyl cellulose (CMC) are added into deionized water in a weight ratio of 94.5:1:0.375:2.8:1.325, wherein the mass fraction of silicon oxide is 70%, based on the mass of artificial graphite and silicon oxide, and mixed and stirred for 0.5-6h to obtain negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode current collector copper foil in layers, and dried, cold pressed, and cut to obtain negative electrode sheets.
  • lithium salt LiPF 6 /LIFSI was dissolved in an organic solvent of ethylene carbonate/ethyl methyl carbonate/diethyl carbonate/fluoroethylene carbonate (volume ratio of 1:1:1:1), and stirred evenly to obtain a lithium salt concentrate. 1 mol/L electrolyte.
  • a polypropylene film is used as a base film, and 1 micron aluminum oxide and 1 micron polyvinylidene fluoride are coated on the base film.
  • the positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is between the positive and negative electrode sheets to play an isolating role, and then wound to obtain a bare cell, the bare cell is welded with a pole ear, and the bare cell is placed in an aluminum shell, and baked at 80°C to remove water, and then the electrolyte is injected and sealed to obtain an uncharged battery.
  • the uncharged battery is then subjected to the processes of static, hot and cold pressing, formation, shaping, and capacity testing in sequence to obtain the lithium battery product of Example 1.
  • the preparation methods of the batteries of Examples 2 to 24 are similar to those of the battery of Example 1, but the components of the positive electrode active material and the preparation method thereof are adjusted. The specific parameters are shown in Table 1.
  • the preparation method of the battery of Comparative Example 1 is similar to that of the battery of Example 1, but the hard template of carbon spheres is not added during the coprecipitation reaction.
  • the preparation method is as follows:
  • the preparation methods of the batteries of Comparative Examples 2 to 3 are similar to those of the batteries of Example 1, but the parameters of the preparation method of the positive electrode active material are adjusted. The specific parameters are shown in Table 1.
  • Comparative Example 4 The battery preparation method of Comparative Example 4 is similar to that of Example 21, but the hard template of carbon spheres is not added during the reaction process. The specific parameters are shown in Table 1.
  • Stick the conductive glue on the sample table take the powdered samples of the positive active materials in each embodiment and comparative example and spread them on the conductive glue, blow away the unadhered powder with an ear bulb, spray gold, and use argon plasma to cross-section the particles of the powdered sample.
  • Use a scanning electron microscope (such as ZEISS Sigma 300) at an acceleration voltage of 10kV and an emission current of 10mA to obtain a scanning electron microscope photo of the powdered sample.
  • Measure the inner diameter of the hollow structure based on the SEM image measure at least three samples, measure at least 50 data for each sample, and take the number average as the inner diameter of the hollow structure of the sample.
  • the porosity of the positive electrode active material can be tested by any means known in the art.
  • the porosity is measured by the gas displacement method according to GB/T24586.
  • Porosity (V1-V2)/V1*100%, where V1 is the apparent volume of the sample and V2 is the actual volume of the sample.
  • Stick the conductive glue on the sample table take the powdered samples of the positive electrode active materials in each embodiment and comparative example and spread them on the conductive glue, blow away the unadhered powder with an ear-cleaning bulb, spray gold, and use argon plasma to cross-section the particles of the powdered sample.
  • Use a scanning electron microscope (such as ZEISS Sigma 300) at an acceleration voltage of 10kV and an emission current of 10mA to obtain a scanning electron microscope photo of the powdered sample.
  • Measure the outer wall thickness of the hollow structure based on the SEM image measure at least three samples, measure at least 50 data for each sample, and take the number average as the outer wall thickness of the hollow structure of the sample.
  • the particle size distribution laser diffraction method of GB/T 19077-2016 weigh 0.1g to 0.13g of the positive electrode active material sample to be tested in a 50mL beaker, add 5g of anhydrous ethanol, and place it in a After the stirring bar is 2.5mm, it is sealed with plastic wrap. After ultrasonic treatment for 5 minutes, the sample is transferred to a magnetic stirrer and stirred at 500 rpm for more than 20 minutes. Two samples are taken from each batch of products for testing. The Mastersizer 2000E laser particle size analyzer of Malvern Instruments Co., Ltd., UK, is used for testing. Among them, Dv50 is the particle size corresponding to the cumulative volume distribution percentage of the secondary particles of the positive electrode active material reaching 50%.
  • 0.1g to 0.13g of the positive electrode active material sample to be tested was weighed in a 50mL beaker, 5g of anhydrous ethanol was added, and a stirring bar of about 2.5mm was placed and sealed with plastic wrap. After ultrasonic treatment for 5min, the sample was transferred to a magnetic stirrer and stirred at 500 rpm for more than 20min. Two samples were taken for testing from each batch of products. The Mastersizer 2000E laser particle size analyzer of Malvern Instruments Co., Ltd., UK, was used for testing.
  • SPAN (Dv90-Dv10)/Dv50
  • the Dv90 of the secondary particles is the particle size corresponding to the cumulative volume distribution percentage of the secondary particles of the positive electrode active material reaching 90%
  • the Dv50 of the secondary particles is the particle size corresponding to the cumulative volume distribution percentage of the secondary particles of the positive electrode active material reaching 50%
  • the Dv10 of the secondary particles is the particle size corresponding to the cumulative volume distribution percentage of the secondary particles of the positive electrode active material reaching 10%.
  • the (101) crystal surface area was tested by X-ray powder diffractometer (XRD, instrument model: Bruker D8ADVANCE), with Cu K ⁇ as the target material; the voltage and current were 40 KV/40 mA, the scanning angle range was 5° to 80°, the scanning step length was 0.00836°, and the time for each step was 0.3 s.
  • XRD X-ray powder diffractometer
  • Capacity test of battery cells Let the battery cells stand at 25°C for 2h, and ensure that the temperature of the battery cells is 25°C. At 25°C, charge the battery cells at 0.1C to the charge cut-off voltage, and continue to charge at the charge cut-off voltage until the current reaches 0.05C and the charge is cut off (where C represents the rated capacity of the battery cells). Let the battery cells stand at 25°C for 1h. At 25°C, discharge the battery cells at 0.1C to the discharge cut-off voltage, and record the total discharge capacity C0 released by the battery cells. The total discharge energy is E0.
  • Battery cell weight measurement Place the battery cell on an electronic balance until the weight is stable, and read the battery cell weight value M0.
  • Battery cell discharge energy E0/battery cell weight M0 is the energy density of the battery cell.
  • Voltage calibration let the stacked three-electrode battery cell of the same battery design stand at 25°C for 30min; at 25°C, charge the battery cell at 0.33C to the charge cut-off voltage, and then continue to charge at a constant voltage at the charge cut-off voltage until the current reaches 0.05C and the charge is cut off (where C represents the rated capacity of the battery cell); let it stand at 25°C for 1h; at 25°C, discharge the battery cell at 0.33C to the discharge cut-off voltage, and record the total discharge capacity C1 of the battery cell; let it stand at 25°C for 1h.
  • Charging test the stacked three-electrode cell was left at 25°C for 30min; 0.33C1DC to discharge cut-off voltage; left at rest for 5min; xC1CC to charge cut-off voltage (three electrodes monitor anode potential, jump to next step when anode potential is 0V; repeat the above steps 9 times, x values are 5, 4, 4.5, 3, 2, 1, 0.8, 0.5, 0.33 respectively; take the x value and charging capacity Cx corresponding to anode potential of 0V.
  • the secondary battery prepared in each embodiment and comparative example is charged at a constant current of 0.5C to a charge cut-off voltage of 4.25V, then charged at a constant voltage to a current of ⁇ 0.05C, left to stand for 5 minutes, and then discharged at a constant current of 0.33C to a discharge cut-off voltage of 2V, left to stand for 5 minutes. This is a charge and discharge cycle.
  • the battery is tested for cyclic charge and discharge according to this method until the battery capacity decays to 80%. The number of cycles at this time is the cycle life of the battery at 25°C.
  • the batteries of the embodiments and comparative examples were prepared according to the above method, and various performance parameters were measured. The results are shown in Tables 1, 2 and 3 below.
  • the chemical formula of the positive electrode active material in Examples 1 to 24 is any one of LiNi 0.97 Co 0.02 Mn 0.01 O 2 , LiNi 0.97 Co 0.03 O 2 , LiNi 0.995 Co 0.004 Mn 0.001 O 2 , LiNi 0.95 Co 0.04 Mn 0.01 O 2 , and LiNi 0.97 Co 0.02 Sb 0.01 O 2 .
  • the morphology of the positive electrode active material in Example 4 was tested using a scanning electron microscope (SEM). The test results are shown in Figure 1. It can be seen from the figure that the positive electrode active material has a hollow structure.
  • the positive electrode active materials in Examples 1 to 24 all have a hollow structure, and the inner diameter d1 of the hollow structure is 0.3 ⁇ m-5 ⁇ m.
  • the positive electrode active material has a hollow structure, which can increase the discharge capacity and energy density of the battery, shorten the charging time of the battery, improve the rate performance of the battery, and improve the cycle performance of the battery.
  • the inner diameter d1 of the hollow structure is 0.3 ⁇ m-5 ⁇ m, which can improve the cycle performance of the battery.
  • the battery has high discharge capacity and energy density, excellent rate performance, and comprehensively improves the electrochemical performance of the battery.
  • the inner diameter d1 of the hollow structure is 1.5 ⁇ m-5 ⁇ m, which can further improve the cycle performance and rate performance of the battery.
  • the outer wall thickness d2 of the hollow structure is 3 ⁇ m-10 ⁇ m, the battery has a high discharge capacity and energy density, excellent rate performance and cycle performance, and comprehensively improves the electrochemical performance of the battery. From the comparison of Examples 2 to 4, 6 to 20 with Examples 1 and 5, it can be seen that the outer wall thickness d2 of the hollow structure is 3 ⁇ m-7 ⁇ m, which can further improve the cycle performance and rate performance of the battery.
  • the Dv50 of the positive electrode active material is 5 ⁇ m-15 ⁇ m, which can improve the energy density and rate performance of the battery. From the comparison between Examples 4, 7, 11 to 16 and Examples 9 to 10, it can be seen that the Dv50 of the positive electrode active material is 8 ⁇ m-10 ⁇ m, which can further improve the energy density and rate performance of the battery.
  • the porosity of the positive electrode active material is 0-20%, the battery has a high discharge capacity and energy density, has excellent rate performance and cycle performance, and comprehensively improves the electrochemical performance of the battery. It can be seen from the comparison of Examples 2 to 4, 6 to 8, 13 to 16 with Examples 1 and 5 that the porosity of the positive electrode active material is 2%-15%, which can increase the discharge capacity and energy density of the battery, and improve the rate performance and cycle performance of the battery.
  • the specific surface area of the positive electrode active material is 0.4 m 2 /g-1.4 m 2 /g, the battery has a high discharge capacity and energy density, excellent rate performance and cycle performance, and comprehensively improves the electrochemical performance of the battery.
  • the SPAN of the positive electrode active material is 1-1.5, which can improve the discharge capacity of the battery. From the comparison between Examples 4 and 15 and Examples 13 to 14 and 16, it can be seen that the SPAN of the positive electrode active material is 1.2-1.4, which can take into account the cycle performance and rate performance of the battery and comprehensively improve the electrochemical performance of the battery.
  • the (010) crystal plane area of the positive electrode active material is greater than or equal to 6 ⁇ m 2 , the battery has a high discharge capacity and energy density, excellent rate performance and cycle performance, and comprehensively improves the electrochemical performance of the battery.
  • the primary particle size of the positive electrode active material is 0.1-0.8 ⁇ m, which can increase the discharge capacity and energy density of the battery and improve the rate performance of the battery. From the comparison between Examples 18 to 19 and Examples 17 and 20, it can be seen that the primary particle size of the positive electrode active material is 0.15-0.3 ⁇ m, which can improve the cycle performance of the battery.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

本申请提供了一种正极活性材料、及其制备方法、二次电池和用电装置。正极活性材料的化学式为LiaNixCoyM1-x-yO2，其中，M包括Mn、Al、B、Zr、Sr、Y、Sb、W、Ti、Mg、Nb中的一种或多种，0.55≤x≤1.0，0≤y≤0.45，0.8≤a≤1.2，且正极活性材料为中空结构，中空结构的内径d1为0.3μm-5μm。

Description

正极活性材料、及其制备方法、正极极片、二次电池和用电装置 技术领域
本申请涉及二次电池技术领域，尤其涉及一种正极活性材料、及其制备方法、正极极片、二次电池和用电装置。
背景技术
二次电池具有容量高、寿命长等特性，因此广泛应用于电子设备，例如手机、笔记本电脑、电瓶车、电动汽车、电动飞机、电动轮船、电动玩具汽车、电动玩具轮船、电动玩具飞机和电动工具等等。由于二次电池取得了极大的进展，因此对二次电池的性能提出了更高的要求。为了提高二次电池的性能，通常对二次电池内的材料例如正极活性材料进行优化改善。正极活性材料作为二次电池中金属离子的和电子的载体，起到能量的存储与释放的作用，对二次电池的性能具有不可忽略的影响。然而，目前改进后的正极活性材料在应用于二次电池时，二次电池的循环性能和倍率性能仍较差。
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活性材料，该正极活性材料具有中空结构，且中空结构的内径为0.3μm-5μm，能够有效提高电池的循环性能，同时电池具有优异的倍率性能。
本申请的第一方面提供一种正极活性材料，正极活性材料的化学式为LiaNixCoyM1-x-yO2，
其中，M包括Mn、Al、B、Zr、Sr、Y、Sb、W、Ti、Mg、Nb中的一种或多种，0.55≤x≤1.0，0≤y≤0.45，0.8≤a≤1.2，且正极活性材料为中空结构，中空结构的内径d1为0.3μm-5μm。
一方面，由于中空结构的存在，可以缓冲正极活性材料在充放电过程中的体积变化，起到稳定结构、改善循环性能的作用。另一方面，具有中空结构的正极活性材料存在较多的三维孔道，扩大材料与电解液的接触面积，缩短锂离子的迁移距离，减小电池内阻，电池具有优异的倍率性能。同时另外具有中空结构的正极活性材料具有更多锂离子的活性位点，提升材料的克容量，提高材料的放电容量和能量密度。
在任意实施方式中，化学式LiaNixCoyM1-x-yO2中，0.9≤x≤1.0，0≤y≤0.1，0.8≤a≤1.2，可选地0.95≤x≤0.995，0≤y≤0.05，0.8≤a≤1.2。
在任意实施方式中，中空结构的内径d1为1.5μm-5μm，可以进一步缩短锂离子迁移距离，改善电池的倍率性能。
在任意实施方式中，正极活性材料满足如下关系式：1≤Dv50/(d1+d2)≤4，
其中d1μm为中空结构的内径，d2μm为中空结构的外壁厚度，Dv50μm为正极活性材料的Dv50。
通过控制正极活性材料的Dv50与中空结构的内径d1和外壁厚度d2满足：1≤Dv50/(d1+d2)≤4，可以提高电池的能量密度，改善电池的倍率性能。
在任意实施方式中，中空结构的外壁壁厚d2为3μm-10μm，可选为3μm-7μm。
控制中空结构的外壁壁厚d2在合适范围内，可以提高材料的结构稳定性，电池具有高的放电容量和能量密度，具有优异的倍率性能和循环性能，综合改善电池的电化学性能。
在任意实施方式中，正极活性材料的Dv50为5μm-15μm，可选为8μm-10μm。
控制正极活性材料的Dv50在合适范围内，可以提高电池的能量密度和倍率性能。
在任意实施方式中，正极活性材料的孔隙率为0-20％，可选为2％-15％。
控制正极活性材料的孔隙率在合适范围内，电池具有高的放电容量和能量密度，具有优异的倍率性能和循环性能，综合改善电池的电化学性能。
在任意实施方式中，正极活性材料的比表面积为0.4m2/g-1.4m2/g。
控制正极活性材料的比表面积在合适范围内，电池具有高的放电容量和能量密度，具有优异的倍率性能和循环性能，综合改善电池的电化学性能。
在任意实施方式中，正极活性材料的SPAN为1-1.5，可选为1.2-1.4。
控制正极活性材料的SPAN在合适范围内，可以提高电池的放电容量。
在任意实施方式中，正极活性材料的(010)晶面面积大于等于6μm2。
控制正极活性材料的(010)晶面面积大于等于6μm2，电池具有高的放电容量和能量密度，具有优异的倍率性能和循环性能，综合改善电池的电化学性能。
在任意实施方式中，正极活性材料的一次颗粒粒径为0.1-0.8μm，可选为0.15-0.3μm。
控制正极活性材料的一次颗粒粒径在合适范围内，可以提高电池的放电容量和能量密度，改善电池的倍率性能。
本申请的第二方面提供一种正极活性材料的制备方法，包括步骤(1)和步骤(2)：
步骤(1)：将包含镍源、钴源的混合源与硬模板剂、络合剂、沉淀剂混合，进行共沉淀反应，得到前驱体，可选地，混合源中含有M源，
步骤(2)：将前驱体与锂源煅烧得到正极活性材料，
正极活性材料的化学式为LiaNixCoyM1-x-yO2，
其中，M包括Mn、Al、B、Zr、Sr、Y、Sb、W、Ti、Mg、Nb 中的一种或多种，0.55≤x≤1.0，0≤y≤0.45，0.8≤a≤1.2，正极活性材料为中空结构，中空结构的内径为0.3μm～5μm。
利用共沉淀反应在硬模板剂表面包覆一层紧密的镍钴氢氧化物，形成紧凑的核壳结构，后续通过煅烧除去硬模板剂，获得具有中空结构的正极活性材料。上述正极活性材料的制备方法简单，制作成本低。制备的正极活性材料具有内径为0.3μm～5μm的中空结构，有利于锂离子的嵌入和脱出，同时中空结构可以缓冲正极活性材料在充放电过程中的体积变化，起到稳定结构、改善循环性能。
在任意实施方式中，化学式LiaNixCoyM1-x-yO2中，0.9≤x≤1.0，0≤y≤0.1，0.8≤a≤1.2，可选地0.95≤x≤0.995，0≤y≤0.05，0.8≤a≤1.2。
在任意实施方式中，硬模板剂的平均直径为0.2μm-3μm，可选为1μm-3μm。
控制硬模板剂的平均直径在合适范围内，进而控制正极活性材料中空结构的内径在合适范围内，可以兼顾锂离子的扩散路径和中空结构的稳定性，综合改善电池的循环性能和倍率性能。
在任意实施方式中，硬模板剂包括碳氮复合球、碳球、酚醛树脂微球、密胺树脂微球中的一种或多种，可选地包括酚醛树脂球。
在任意实施方式中，步骤(1)中投入的硬模板剂的重量和混合源中的镍元素和钴元素总重量之比为1:20-3:4，
或者步骤(1)中投入的硬模板剂的重量和混合源中的镍元素、钴元素和M元素总重量之比为1:20-3:4。
控制硬模板剂与混合源中的镍元素、钴元素和/或M元素的总重量在合适范围内，使得镍钴氢氧化物层在硬模板剂表面的稳定包覆且均匀包覆，使得中空结构具有合适的内径和外壁厚度，正极活性材料具有优异的结构性能，改善电池的循环性能和倍率性能。
在任意实施方式中，步骤(1)中的共沉淀反应的pH值为9-13。
合适的共沉淀反应的pH值，共沉淀反应更平稳，更高效，使得镍钴氢氧化物层在硬模板剂表面的稳定包覆且均匀包覆，使得中空结构具有合适的内径和外壁厚度，正极活性材料具有优异的结构性 能，改善电池的循环性能和倍率性能。
在任意实施方式中，步骤(1)中共沉淀反应的反应温度为60-85℃。
合适的共沉淀反应温度，共沉淀反应更平稳，更高效，使得镍钴氢氧化物层在硬模板剂表面的稳定包覆且均匀包覆，使得中空结构具有合适的内径和外壁厚度，正极活性材料具有优异的结构性能，改善电池的循环性能和倍率性能。
在任意实施方式中，步骤(1)中共沉淀反应的反应时间为5-20h。
合适的共沉淀反应的反应时间，共沉淀反应更平稳，更高效，使得镍钴氢氧化物层在硬模板剂表面的稳定包覆且均匀包覆，使得中空结构具有合适的内径和外壁厚度，正极活性材料具有优异的结构性能，改善电池的循环性能和倍率性能。
在任意实施方式中，步骤(1)中共沉淀反应搅拌的速度为200-900rpm。
合适的共沉淀反应搅拌的速度，共沉淀反应更平稳，更高效，使得镍钴氢氧化物层在硬模板剂表面的稳定包覆且均匀包覆，使得中空结构具有合适的内径和外壁厚度，正极活性材料具有优异的结构性能，改善电池的循环性能和倍率性能。
在任意实施方式中，步骤(1)具体包括：
配制质量浓度为1-10g/L的硬模板剂溶液、摩尔浓度为1-2mol/L的沉淀剂溶液、摩尔浓度为4-8mol/L的络合剂溶液、包含镍元素、钴元素总摩尔浓度为1-2mol/L的混合盐溶液，可选的混合盐溶液还包含M元素；
将沉淀剂溶液、络合剂溶液及所述混合盐溶液合流加至所述硬模板剂溶液中；
进行共沉淀反应，得到前驱体。
控制硬模板剂、沉淀剂、络合剂、混合盐溶液在合适范围内，共沉淀反应更平稳和高效，且在共沉淀反应过程中，镍钴氢氧化物 可以更缓慢稳定且紧密的沉淀在硬模板剂表面，在硬模板剂表面形成更均匀的壳层结构，使得中空结构具有合适的内径、外壁厚度和Dv50，正极活性材料具有优异的结构性能，提高电池的循环性能和倍率性能。
在任意实施方式中，步骤(2)中的煅烧温度为700-900℃；
步骤(2)中的煅烧时间为6-18h。
控制煅烧温度和时间在合适范围内，保证能完全除去硬模板剂，形成中空结构，同时还需要保证正极活性材料结构的稳定性，正极活性材料具有稳定的中空结构，提高电池的循环性能和倍率性能。
本申请的第三方面提供一种正极极片，正极极片包括第一方面的正极活性材料或第二方面的制备方法制备的正极活性材料。
本申请的第四方面提供一种二次电池，包括第三方面的正极极片。
本申请的第五方面提供一种用电装置，包括权第四方面的二次电池。
附图说明
图1是本申请实施例4所示的正极活性材料扫描电镜图；
图2是本申请一实施方式的二次电池的示意图；
图3是图2所示的本申请一实施方式的二次电池的分解图；
图4是本申请一实施方式的电池模块的示意图；
图5是本申请一实施方式的电池包的示意图；
图6是图5所示的本申请一实施方式的电池包的分解图；
图7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盖板。
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活性材料、及其制备方法、二次电池和用电装置的实施方式。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)。
现有技术中富镍的三元材料由于具有高的理论比容量，放电平台高、廉价易成为热门的二次电池正极活性材料之一。但是三元材料中Ni+2离子半径和Li+的半径相近会严重出现阳离子混排的现象，使得材料的电化学性能衰退，尤其在高镍体系中，阳离子混排趋势增加，电池循环性能恶化；另一方面，锂离子电池在充放电过程中也会由于界面副反应的存在，会导致电解液在正负极的界面持续的分解，以及正极活性材料界面相变，从而引起活性Li的损失和锂离子电池阻抗的增加，导致材料的倍率性能降低。需要开发一种高比容量、具有优异的循环性能和倍率性能的正极活性材料，以满足新一代电化学体系的应用需要。
[正极活性材料]
基于此，本申请的提出了一种正极活性材料，正极活性材料的化学式为LiaNixCoyM1-x-yO2，
其中，M包括Mn、Al、B、Zr、Sr、Y、Sb、W、Ti、Mg、Nb中的一种或多种，0.55≤x≤1.0，0≤y≤0.45，0.8≤a≤1.2，且正极活性材料为中空结构，中空结构的内径d1为0.3μm-5μm。
在本文中，术语“中空结构”是指由明显的壳层围成内部有空腔的固体结构。
在本文中，术语“中空结构的内径”是指正极活性材料的内部空腔的圆形或类圆形的横截面的最长直径。
中空结构的内径可以采用本领域公知的任意手段进行测试。作为示例，将样品台上贴好导电胶，取正极活性材料的粉末状样品平铺于导电胶上，用洗耳球吹走未粘上的粉末，喷金，使用氩气等离子体对粉末状样品的颗粒进行截面切割。使用扫描电子显微镜在加速电压为10kV，发射电流为10mA的条件下，得到粉末状样品的扫描电镜照片。根据扫，扫描电镜照片测量中空结构的内径尺寸，至少测量三个样品，每个样品至少测量50个数据，取数均平均值作为样品的中空结构的内径尺寸。
在一些实施方式中，化学式LiaNixCoyM1-x-yO2中，a为0.8、0.9、1.0、1.1、1.2中的任意值或其中任意两值组成的范围。
在一些实施方式中，化学式LiaNixCoyM1-x-yO2中，x为0.55、0.6、0.7、0.8、0.9、0.95、0.995中的任意值或其中任意两值组成的范围。
在一些实施方式中，化学式LiaNixCoyM1-x-yO2中，y为0、0.1、0.2、0.3、0.4、0.45中的任意值或其中任意两值组成的范围。
在一些实施方式中，化学式LiaNixCoyM1-x-yO2中，0.90≤x≤1.0，0≤y≤0.1，0.8≤a≤1.2。
在一些实施方式中，化学式LiaNixCoyM1-x-yO2中，0.95≤x≤0.995，0≤y≤0.05，0.8≤a≤1.2。
在一些实施方式中，正极活性材料的化学式为LiaNixCoyMn1-x- yO2，0.95≤x≤0.995，0≤y≤0.05，0.8≤a≤1.2。
在一些实施方式中，正极活性材料的化学式为LiaNixCoySb1-x-yO2，0.95≤x≤0.995，0≤y≤0.05，0.8≤a≤1.2。
在一些实施方式中，正极活性材料的化学式为LiaNixCoyO2，0.95≤x≤0.995，0.005≤y≤0.05，x+y＝1，0.8≤a≤1.2。
采用上述材料可以确保正极活性材料具有高的克容量，使得电池具有高的放电容量和能量密度。
在一些实施方式中，中空结构的内径d1可选为0.3μm-0.5μm、 0.3μm-0.9μm、0.3μm-1μm、0.3μm-2μm、0.3μm-3μm、0.3μm-4μm、0.3μm-5μm、1μm-2μm、1μm-3μm、1μm-4μm、1μm-5μm、2μm-3μm、2μm-4μm、2μm-5μm、3μm-4μm、3μm-5μm、4μm-5μm中的任意一种。
一方面，由于中空结构的存在，可以缓冲正极活性材料在充放电过程中的体积变化，起到稳定结构、改善循环性能的作用。另一方面，具有中空结构的正极活性材料存在较多的三维孔道，扩大材料与电解液的接触面积，缩短锂离子的迁移距离，减小电池内阻，电池具有优异的倍率性能。同时另外具有中空结构的正极活性材料具有更多锂离子的活性位点，提升材料的克容量，提高材料的放电容量和能量密度。
在一些实施方式中，中空结构的内径d1为1.5μm-5μm。在一些实施方式中，中空结构的内径d1可选为1.5μm-3μm、2μm-4μm、2μm-5μm、3μm-4μm、3μm-5μm、4μm-5μm中的任意一种。
中空结构的内径d1在合适范围内，可以进一步缩短锂离子迁移距离，改善电池的倍率性能。
在一些实施方式中，正极活性材料满足如下关系式：1≤Dv50/(d1+d2)≤4，
其中d1μm为中空结构的内径，d2μm为中空结构的外壁厚度，Dv50μm为正极活性材料的Dv50。
在一些实施方式中，正极活性材料满足如下关系式中的任意一种：1≤Dv50/(d1+d2)≤2、1≤Dv50/(d1+d2)≤3、1≤Dv50/(d1+d2)≤4、2≤Dv50/(d1+d2)≤3、2≤Dv50/(d1+d2)≤4、3≤Dv50/(d1+d2)≤4，
其中d1μm为中空结构的内径，d2μm为中空结构的外壁厚度，Dv50μm为正极活性材料的Dv50。
在本文中，术语“中空结构的外壁厚度”是指中空结构的外部壳层的厚度。
中空结构的外壁厚度可以采用本领域公知的任意手段进行测试。 作为示例，将样品台上贴好导电胶，取正极活性材料的粉末状样品平铺于导电胶上，用洗耳球吹走未粘上的粉末，喷金，使用氩气等离子体对粉末状样品的颗粒进行截面切割。使用扫描电子显微镜在加速电压为10kV，发射电流为10mA的条件下，得到粉末状样品的扫描电镜照片。根据扫描电镜图片测量中空结构的外壁厚度，至少测量三个样品，每个样品至少测量50个数据，取数均平均值作为样品的中空结构的外壁厚度。
在本文中，术语“Dv50”是指正极活性材料的中值粒度。具体地，Dv50表示正极活性材料在体积基准的粒度分布中，从小粒径侧起、达到体积累积50％的粒径。
正极活性材料的Dv50可以采用本领域公知的任意手段进行测试。作为示例，正极活性材料的Dv50数值可以参照GB/T19077-2016规定的方法测量。
正极活性材料的Dv50、中空结构的内径d1和外壁厚度d2是正极活性材料结构的重要参数，影响着材料的结构性能。正极活性材料的Dv50、中空结构的内径d1和外壁厚度d2在合适范围内，材料具有较多的锂离子的活性位点，提升材料克容量，从而提高材料的电池密度，同时可以改善材料的结构稳定性，锂镍混排现象得到有效改善，锂离子和电子的迁移速率明显提高，提高材料的倍率性能。
通过控制正极活性材料的Dv50与中空结构的内径d1和外壁厚度d2满足：1≤Dv50/(d1+d2)≤4，可以提高电池的能量密度，改善电池的倍率性能。
在一些实施方式中，中空结构的外壁壁厚d2为3μm-10μm。在一些实施方式中，中空结构的外壁壁厚d2可选为3μm-4μm、3μm-5μm、3μm-6μm、3μm-7μm、3μm-8μm、3μm-9μm、3μm-10μm、4μm-5μm、4μm-6μm、4μm-7μm、4μm-8μm、4μm-9μm、4μm-10μm、5μm-6μm、5μm-7μm、5μm-8μm、5μm-9μm、5μm-10μm、6μm-7μm、6μm-8μm、6μm-9μm、6μm-10μm、7μm-8μm、7μm-9μm、7μm-10μm、8μm-9μm、8μm-10μm、9μm-10μm中的 任意一种。
控制中空结构的外壁壁厚d2在合适范围内，可以提高材料的结构稳定性，电池具有高的放电容量和能量密度，具有优异的倍率性能和循环性能，综合改善电池的电化学性能。
在一些实施方式中，中空结构的外壁壁厚d2为3μm-7μm。在一些实施方式中，中空结构的外壁壁厚d2可选为3μm-4μm、3μm-5μm、3μm-6μm、3μm-7μm、4μm-5μm、4μm-6μm、4μm-7μm、5μm-6μm、5μm-7μm、6μm-7μm中的任意一种。
中空结构的外壁厚度在合适范围内，可以进一步提高电池的循环性能和倍率性能。
在一些实施方式中，正极活性材料的Dv50为5μm-15μm。在一些实施方式中，正极活性材料的Dv50为5μm-9μm、5μm-10μm、5μm-15μm、9μm-10μm、9μm-15μm、10μm-15μm中的任意一种。
不同粒径的颗粒的面积不同，具有不同数量的反应活性位点，因此颗粒粒径的大小会影响到离子的脱嵌和嵌入速度，影响材料的克容量，控制正极活性材料的Dv50在合适范围内，可以提高电池的能量密度和倍率性能。
在一些实施方式中，正极活性材料的Dv50为8μm-10μm。在一些实施方式中，正极活性材料的Dv50为8μm-9μm、8μm-10μm、9μm-10μm中的任意一种。
控制正极活性材料的Dv50在合适范围内，可以进一步提高电池的能量密度和倍率性能。
在一些实施方式中，正极活性材料的孔隙率为0-20％。在一些实施方式中，正极活性材料的孔隙率可选为0-5％、0-10％、0-15％、0-20％、5-10％、5-15％、5-20％、10-15％、10-20％、15-20％中的任意一种。
在本文中，“孔隙率”是指正极活性材料中的孔体积占据正极活性材料总体积的比率。
正极活性材料的孔隙率可以采用本领域公知的任意手段进行测 试。作为示例，按照GB/T24586，采用气体置换法测量。孔隙率＝(V1-V2)/V1*100％，其中V1是样品的表观体积，V2是样品的真实体积。
控制正极活性材料的孔隙率在合适范围内，有利于电解液的浸润，使正极活性材料与电解液充分接触，缩短锂离子传输路径，电池具有高的放电容量和能量密度，具有优异的倍率性能和循环性能，综合改善电池的电化学性能。
在一些实施方式中，正极活性材料的孔隙率为2-15％。在一些实施方式中，正极活性材料的孔隙率可选为2-5％、2-10％、2-15％、5-10％、5-15％、10-15％中的任意一种。
控制正极活性材料的孔隙率在合适范围内，可以进一步提高电池的放电容量和能量密度，改善电池的倍率性能和循环性能。
在一些实施方式中，正极活性材料的比表面积为0.4m2/g-1.4m2/g。在一些实施方式中，正极活性材料的比表面积可选为0.4m2/g-0.7m2/g、0.4m2/g-0.9m2/g、0.5m2/g-0.7m2/g、0.5m2/g-0.9m2/g、0.5m2/g-1.1m2/g、0.7m2/g-0.9m2/g、0.7m2/g-1.1m2/g、0.9m2/g-1.1m2/g中的任意一种。
正极活性材料的比表面积可以采用本领域公知的任意手段进行测试。作为示例，可以参考GB/T 19587-2017《气体吸附BET法测定固态物质比表面积》。采用设备TriStar II 3020进行测定，将正极活性材料分散到分散剂中(乙醇)，超声30分钟后，将得到的材料放入真空干燥箱中干燥，最后使用比表面积测试仪对正极活性材料比表面积进行测量。
正极活性材料的比表面积越大，正极活性材料中的活性位点越多，正极活性材料与电子进行交换的速度越快，电池的动力学性能越好，但是过多的活性位点会增加正极活性材料与电解液的副反应，恶化电池的循环性能，而过少的活性位点会导致电池体系中的化学反应下降，导致电池容量、循环性能变差。
控制正极活性材料的比表面积在合适范围内，电池具有高的放 电容量和能量密度，具有优异的倍率性能和循环性能，综合改善电池的电化学性能。
在一些实施方式中，正极活性材料的SPAN为1-1.5。在一些实施方式中，正极活性材料的SPAN可选为1-1.1、1-1.2、1-1.3、1-1.4、1-1.5、1.1-1.2、1.1-1.3、1.1-1.4、1.1-1.5、1.2-1.3、1.2-1.4、1.2-1.5、1.3-1.4、1.3-1.5、1.4-1.5中的任意一种。
在本文中，术语“SPAN”是指分布跨度，SPAN的计算方式为(Dv90-Dv10)/Dv50，其代表正极活性材料的颗粒分布，其中Dv50表示正极活性材料在体积基准的粒度分布中，从小粒径侧起、达到体积累积50％的粒径；Dv10表示正极活性材料在体积基准的粒度分布中，从小粒径侧起、达到体积累积10％的粒径；Dv90表示正极活性材料在体积基准的粒度分布中，从小粒径侧起、达到体积累积90％的粒径。
参照GB/T19077-2016规定的方法测量得到正极活性材料的Dv50、Dv10、Dv90数值，进而计算得到，正极活性材料的SPAN。
SPAN维持在较宽的范围，可以提高材料的压实密度，可以提高电池的放电容量。
在一些实施方式中，正极活性材料的SPAN为1.2-1.4。在一些实施方式中，正极活性材料的SPAN可选为1.2-1.3、1.2-1.4、1.3-1.4、中的任意一种。
SPAN维持在较宽的范围，存在粒径不同的大小颗粒，避免了电池循环过程中颗粒的开裂，使得电池具有优异的循环性能；合成的前驱体颗粒大小不均一，颗粒与颗粒之间紧密接触，改善锂离子的传输速度，使得电池具有优异的倍率性能。
控制正极活性材料的SPAN在合适范围内，可以兼顾电池的循环性能和倍率性能，综合改善电池的电化学性能。
在一些实施方式中，正极活性材料的(010)晶面面积大于等于6μm2。
在一些实施方式中，正极活性材料的(010)晶面面积大于等于 6μm2、20μm2、50μm2、100μm2、150μm2、200μm2、240μm2、250μm2中的任意一种。
正极活性材料的(010)晶面面积的可以采用本领域公知的任意手段进行测试。作为示例，采用X射线粉末衍射仪(XRD，仪器型号：Bruker D8ADVANCE)测试(101)晶面面积，靶材为Cu Kα；电压电流为40KV/40mA，扫描角度范围为5°至80°，扫描步长为0.00836°，每步长时间为0.3s。
(010)晶面是锂离子传输的优势面，正极活性材料具有多的(010)晶面面积，正极活性材料具有多的锂离子反应活性位点，电池具有优异的动力学性能。
控制正极活性材料的(010)晶面面积大于等于6μm2，电池具有高的放电容量和能量密度，具有优异的倍率性能和循环性能，综合改善电池的电化学性能。
在一些实施方式中，正极活性材料的一次颗粒粒径为0.1-0.8μm。在一些实施方式中，正极活性材料的一次颗粒粒径可选为0.1-0.2μm、0.1-0.3μm、0.1-0.4μm、0.1-0.5μm、0.1-0.6μm、0.1-0.7μm、0.1-0.8μm、0.2-0.3μm、0.2-0.4μm、0.2-0.5μm、0.2-0.6μm、0.2-0.7μm、0.2-0.8μm、0.3-0.4μm、0.3-0.5μm、0.3-0.6μm、0.3-0.7μm、0.3-0.8μm、0.4-0.5μm、0.4-0.6μm、0.4-0.7μm、0.4-0.8μm、0.5-0.6μm、0.5-0.7μm、0.5-0.8μm、0.6-0.7μm、0.6-0.8μm、0.7-0.8μm中的任意一种。
在本文中，术语“一次颗粒”是指正极活性材料未团聚之前的颗粒。
正极活性材料的一次颗粒粒径的可以采用本领域公知的任意手段进行测试。作为示例，通过500倍的扫描电子显微镜成像后，在其电子显微图像中随机选取200至600个形状完整且无遮档的正极活性材料的一次颗粒，并计录一次颗粒在显微图像中最长直径的平均值作为平均粒径。
控制正极活性材料的一次颗粒粒径在合适范围内，缩短锂离子 扩散路径，加快锂离子嵌入和脱出速率，可以提高电池的放电容量和能量密度，改善电池的倍率性能。
在一些实施方式中，正极活性材料的一次颗粒粒径为0.15-0.3μm。在一些实施方式中，正极活性材料的一次颗粒粒径可选为0.15-0.2μm、0.15-0.3μm、0.2-0.3μm中的任意一种。
控制正极活性材料的一次颗粒粒径在合适范围内，一次颗粒具有优异的结构稳定性，在循环充放电的过程中，随着锂离子反复地脱出和嵌入该一次颗粒，一次颗粒仍然能够保持完整的结构，减少一次颗粒内部的过渡金属脱离该一次颗粒而溶出到电解液中的现象，从而提高了电池的循环稳定性。
在一些实施例中，正极活性材料的克容量为238mAh/g-250mAh/g。
正极活性材料中的克容量可以采用本领域公知的任意手段进行测试。作为示例，在25℃、常压环境下，将扣式电池以0.02C倍率恒流充电至电压为3.5V，接著0.1C倍率恒流充电至电压为4.3V再以4.3V恒压充电至电流降到0.05C，记录此时的充电比容量，即为首次脱锂容量；之后以0.1C倍率恒流放电至电压为2.5V，记录此时的放电比容量，为首次嵌锂容量。正极活性材料的克容量即为首次嵌锂容量。
本申请还提出一种正极活性材料的制备方法，包括步骤(1)和步骤(2)：
步骤(1)：将包含镍源、钴源的混合源与硬模板剂、络合剂、沉淀剂混合，进行共沉淀反应，得到前驱体，可选地，混合源中含有M源，
步骤(2)：将前驱体与锂源煅烧得到正极活性材料，
正极活性材料的化学式为LiaNixCoyM1-x-yO2，
其中，M包括Mn、Al、B、Zr、Sr、Y、Sb、W、Ti、Mg、Nb中的一种或多种，0.55≤x≤1.0，0≤y≤0.45，0.8≤a≤1.2，正极活性材料为中空结构，中空结构的内径为0.3μm～5μm。
在本文中，术语“共沉淀反应”是指金属溶液、沉淀剂、络合剂共同在一定温度下进行沉淀反应。
在一些实施方式中，M源为锰源或锑源。
在一些实施方式中，正极活性材料的制备方法，包括步骤(1)和步骤(2)：
步骤(1)：将包含镍源、钴源的混合源与硬模板剂、络合剂、沉淀剂混合，进行共沉淀反应，得到前驱体，
步骤(2)：将前驱体与锂源煅烧得到正极活性材料。
在一些实施方式中，镍源包括硫酸镍、盐酸镍、硝酸镍、醋酸镍中的一种或多种。
在一些实施方式中，钴源包括硫酸钴、盐酸钴、硝酸钴、醋酸钴中的一种或多种。
在一些实施方式中，锰源包括硫酸锰、盐酸锰、硝酸锰、醋酸锰中的一种或多种。
在一些实施方式中，锑源包括硫酸锑、盐酸锑、硝酸锑、醋酸锑中的一种或多种。
利用共沉淀反应在硬模板剂表面包覆一层紧密的镍钴氢氧化物，形成紧凑的核壳结构，后续通过煅烧除去硬模板剂，获得具有中空结构的正极活性材料。上述正极活性材料的制备方法简单，制作成本低。制备的正极活性材料具有内径为0.3μm～5μm的中空结构，有利于锂离子的嵌入和脱出，同时中空结构可以缓冲正极活性材料在充放电过程中的体积变化，起到稳定结构、改善循环性能。
在一些实施方式中，化学式LiaNixCoyM1-x-yO2中，0.9≤x≤1.0，0≤y≤0.1，0.8≤a≤1.2。
在一些实施方式中，化学式LiaNixCoyM1-x-yO2中，0.95≤x≤0.995，0≤y≤0.05，0.8≤a≤1.2。
在一些实施方式中，硬模板剂的平均直径为0.2μm-3μm。在一些实施方式中，硬模板剂的平均直径可选为0.2μm-1μm、0.2μm-2μm、0.2μm-3μm、1μm-2μm、1μm-3μm、2μm-3μm中的任意一种。
在一些实施方式中，硬模板剂的平均直径为1μm-3μm。在一些实施方式中，硬模板剂的平均直径可选为1μm-2μm、1μm-3μm、2μm-3μm中的任意一种。
控制硬模板剂的平均直径在合适范围内，进而控制正极活性材料中空结构的内径在合适范围内，可以兼顾锂离子的扩散路径和中空结构的稳定性，综合改善电池的循环性能和倍率性能。
在一些实施方式中，硬模板剂包括碳氮复合球、碳球、酚醛树脂微球、密胺树脂微球中的一种或多种。
在一些实施方式中，硬模板剂包括酚醛树脂球。
合适的硬模板剂具有优异的吸附性，使得在共沉淀反应中，可以在硬模板剂表面形成一层致密的镍钴氢氧化物，正极活性材料具有优异的结构性能，改善电池的循环性能和倍率性能。
在一些实施方式中，步骤(1)中投入的硬模板剂的重量和混合源中的镍元素和钴元素总重量之比为1:20-3:4，
在一些实施方式中，步骤(1)中投入的硬模板剂的重量和混合源中的镍元素、钴元素和M元素总重量之比为1:20-3:4。
在一些实施方式中，步骤(1)中投入的硬模板剂的重量和混合源中的镍元素和钴元素总重量之比为1:20、1:15、1:10、1:5、1:4、2:4、3:4中的任意值或其中任意两值组成的范围。
在一些实施方式中，步骤(1)中投入的硬模板剂的重量和混合源中的镍元素、钴元素和M元素总重量之比为1:20、1:15、1:10、1:5、1:4、2:4、3:4中的任意值或其中任意两值组成的范围。
在一些实施方式中，步骤(1)中投入的硬模板剂的重量和混合源中的镍元素、钴元素和锰元素总重量之比为1:20、1:15、1:10、1:5、1:4、2:4、3:4中的任意值或其中任意两值组成的范围。
控制硬模板剂与混合源中的镍元素、钴元素和/或M元素的总重量在合适范围内，使得镍钴氢氧化物层在硬模板剂表面的稳定包覆且均匀包覆，使得中空结构具有合适的内径和外壁厚度，正极活性材料具有优异的结构性能，改善电池的循环性能和倍率性能。
在一些实施方式中，步骤(1)中的共沉淀反应的pH值为9-13。
在一些实施方式中，pH值为9、10、11、12、13中的任意值或其中任意两值组成的范围。
合适的共沉淀反应的pH值，共沉淀反应更平稳，更高效，使得镍钴氢氧化物层在硬模板剂表面的稳定包覆且均匀包覆，使得中空结构具有合适的内径和外壁厚度，正极活性材料具有优异的结构性能，改善电池的循环性能和倍率性能。
在一些实施方式中，步骤(1)中共沉淀反应的反应温度为60-85℃。
在一些实施方式中，反应温度为60℃、70℃、80℃、85℃中的任意值或其中任意两值组成的范围。
合适的共沉淀反应温度，共沉淀反应更平稳，更高效，使得镍钴氢氧化物层在硬模板剂表面的稳定包覆且均匀包覆，使得中空结构具有合适的内径和外壁厚度，正极活性材料具有优异的结构性能，改善电池的循环性能和倍率性能。
在一些实施方式中，步骤(1)中共沉淀反应的反应时间为5-20h。
在一些实施方式中，反应时间为5h、10h、15h、20h中的任意值或其中任意两值组成的范围。
合适的共沉淀反应的反应时间，共沉淀反应更平稳，更高效，使得镍钴氢氧化物层在硬模板剂表面的稳定包覆且均匀包覆，使得中空结构具有合适的内径和外壁厚度，正极活性材料具有优异的结构性能，改善电池的循环性能和倍率性能。
在一些实施方式中，步骤(1)中共沉淀反应搅拌的速度为200-900rpm。
在一些实施方式中，反应搅拌的速度为200rpm、300rpm、400rpm、500rpm、600rpm、700rpm、800rpm、900rpm中的任意值或其中任意两值组成的范围。
合适的共沉淀反应搅拌的速度，共沉淀反应更平稳，更高效， 使得镍钴氢氧化物层在硬模板剂表面的稳定包覆且均匀包覆，使得中空结构具有合适的内径和外壁厚度，正极活性材料具有优异的结构性能，改善电池的循环性能和倍率性能。
在一些实施方式中，步骤(1)具体包括：
配制质量浓度为1-10g/L的硬模板剂溶液、摩尔浓度为1-2mol/L的沉淀剂溶液、摩尔浓度为4-8mol/L的络合剂溶液、包含镍元素、钴元素总摩尔浓度为1-2mol/L的混合盐溶液，可选的混合盐溶液还包含M元素；
将沉淀剂溶液、络合剂溶液及混合盐溶液合流加至所述硬模板剂溶液中；
进行共沉淀反应，得到前驱体。
在一些实施方式中，沉淀剂包括氢氧化钠、碳酸钠、碳酸氢钠、碳酸氢铵、的一种或多种，可选为碳酸氢铵。
在一些实施方式中，络合剂包括氨水、乳酸、聚乙烯吡咯烷酮、的一种或多种，可选为氨水。
在一些实施方式中，硬模板剂溶液的质量浓度为1g/L、2g/L、3g/L、4g/L、5g/L、6g/L、7g/L、8g/L、9g/L、10g/L中的任意值或其中任意两值组成的范围。
在一些实施方式中，沉淀剂溶液的摩尔浓度为1mol/L、1.5mol/L、2mol/L中的任意值或其中任意两值组成的范围。
在一些实施方式中，络合剂溶液的摩尔浓度为4mol/L、5mol/L、6mol/L、7mol/L、8mol/L中的任意值或其中任意两值组成的范围。
在一些实施方式中，混合盐的摩尔浓度为1mol/L、1.5mol/L、2mol/L中的任意值或其中任意两值组成的范围。
控制硬模板剂、沉淀剂、络合剂、混合盐溶液在合适范围内，共沉淀反应更平稳和高效，且在共沉淀反应过程中，镍钴氢氧化物可以更缓慢稳定且紧密的沉淀在硬模板剂表面，在硬模板剂表面形成更均匀的壳层结构，使得中空结构具有合适的内径、外壁厚度和Dv50，正极活性材料具有优异的结构性能，提高电池的循环性能和 倍率性能。
在一些实施方式中，步骤(2)中的煅烧温度为700-900℃；
步骤(2)中的煅烧时间为6-18h。
在一些实施方式中，步骤(2)中的煅烧温度为700℃、800℃、900℃中的任意值或其中任意两值组成的范围。
在一些实施方式中，步骤(2)中的煅烧时间为6h、7h、8h、9h、10h、11h、12h、13h、14h、15h、16h、17h、18h中的任意值或其中任意两值组成的范围。
控制煅烧温度和时间在合适范围内，保证能完全除去硬模板剂，形成中空结构，同时还需要保证正极活性材料结构的稳定性，正极活性材料具有稳定的中空结构，提高电池的循环性能和倍率性能。
[正极极片]
正极极片包括正极集流体及形成于正极集流体的至少部分表面上的正极膜层，正极膜层包括一些实施方式中的正极活性材料。
在一些实施方式中，正极膜层的面密度为24～46mg/cm2。
正极膜层的涂布面密度是通过测量单侧的正极膜层的涂布重量(g)和单侧正极膜层的涂布面积(cm2)(采集点数＞14)确定的。具体的，正极膜层的涂布面密度＝单侧的正极膜层的涂布重量(g)/正极膜层的涂布面积(cm2)。
正极膜层还可以包括导电剂，以改善正极的导电性能。导电剂可选为Super P、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨、石墨烯及碳纳米纤维中的一种或几种。
正极膜层还可以包括粘结剂，以将正极活性材料和可选的导电剂牢固地粘结在正极集流体上。粘结剂可选为聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚丙烯酸(PAA)、聚乙烯醇(PVA)、乙烯醋酸乙烯酯共聚物(EVA)、丁苯橡胶(SBR)、羧甲基纤维素(CMC)、海藻酸钠(SA)、聚甲基丙烯酸(PMA)及羧甲基壳聚糖(CMCS)中的至少一种。
正极集流体可以采用导电碳片、金属箔材、涂炭金属箔材、多孔金属板或复合集流体。导电碳片的导电碳材质可选为Super P、炭 黑、科琴黑、碳点、碳纳米管、石墨、石墨烯及碳纳米纤维中的一种或几种，金属箔材、涂炭金属箔材和多孔金属板的金属材质各自独立地选自铜、铝、镍及不锈钢中的至少一种，复合集流体可以为金属箔材与高分子基膜复合形成的复合集流体。
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，例如正极活性材料、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以及设置在负极集流体至少一个表面上的负极膜层。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材料的传统材料。这些负极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，负极活性材料的克容量为600mAh/g-2500mAh/g。
在一些实施方式中，负极活性材料包括氧化亚硅。
在一些实施方式中，基于负极活性材料的总质量计，氧化亚硅的质量含量为20％-100％，可选为50％-100％。
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膜层的组分，例如负极材料、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 氟二草酸磷酸锂及四氟草酸磷酸锂中的至少一种。
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，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。
在一些实施方式中，二次电池可包括外包装。该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硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
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2是作为一个示例的方形结构的 二次电池5。
在一些实施方式中，二次电池的能量密度为380-500Wh/Kg。
在一些实施方式中，参照图3，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。二次电池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，二次电池可以组装成电池模块，电池模块所含二次电池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4是作为一个示例的电池模块4。参照图4，在电池模块4中，多个二次电池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二次电池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，多个二次电池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5和图6是作为一个示例的电池包1。参照图5和图6，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、电池模块、或电池包中的至少一种。所述二次电 池、电池模块、或电池包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二次电池、电池模块或电池包。
图7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。
一、制备方法
实施例1
1)正极活性材料的制备
配制镍、钴、锰元素摩尔比为97:2:1的镍钴锰溶液，浓度调整到2mol/L，其中可溶性镍钴锰的原料分别为硫酸镍、硫酸钴、硫酸锰；配制2mol/L的氢氧化钠溶液；配制6mol/L的氨水溶液；配制质量浓度为10g/L的碳球分散液，置于反应釜中，800rpm搅拌120min至分散均匀。碳球规格：直径0.25μm。
将上述镍钴锰溶液、氢氧化钠溶液及氨水溶液同时加入到反应 釜中进行共沉淀反应，控制转速800rpm，温度60℃，时间6h。调节三种溶液的流量，氢氧化钠溶液的流速为0.5L/min；氨水溶液的流速为0.7L/min；镍钴锰溶液的流速为0.2L/min，控制体系的pH为10.8。其中，碳球的重量和镍钴锰溶液中镍钴锰的总重量之比为1:19。
共沉淀反应完成后，反应物料溢流到陈化釜，加入洗涤添加剂若干，搅拌1小时，然后对物料进行脱水、水洗、二次脱水、烘干筛分、除磁后得到中心为碳球的正极活性材料前驱体。
将该正极活性材料前驱体、碳酸锂按一定比例均匀混合，其中Li/Me摩尔比为1.02；Me为镍元素、钴元素、锰元素总摩尔含量。
将混合均匀的物料放入氧气气氛炉中，升温速率设为5℃/min，在705℃下保温6h，气氛要求为氧气含量≥98％，然后随炉冷却。
将煅烧后得到的物料进行对辊破碎、超离心研磨粉碎，然后400目筛网过筛，即得到正极活性材料。
2)正极极片的制备
将上述正极活性材料、导电剂碳黑、粘结剂聚偏二氟乙烯(PVDF)按质量比为97:1:2，加入N-甲基吡咯烷酮，混合搅拌3h，得到正极浆料；之后将其均匀涂覆于正极集流体铝箔上，经烘干、冷压、分切，得到正极极片。
3)负极极片的制备
将掺杂氧化亚硅的人造石墨、导电剂碳黑、碳纳米管(CNT)、粘结剂丁苯橡胶(SBR)、增稠剂羟甲基纤维素钠(CMC)，按照重量比为94.5:1:0.375:2.8:1.325，其中氧化亚硅的质量分数为70％，基于人造石墨和氧化亚硅的质量计，加入去离子水中，混合搅拌0.5-6h，得到负极浆料；将负极浆料分层均匀涂覆在负极集流体铜箔上，经烘干，冷压、分切，得到负极极片。
4)电解液
在氩气气氛手套箱中(H2O<0.1ppm，O2<0.1ppm)，将锂盐LiPF6/LIFSI溶于有机溶剂碳酸乙烯酯/碳酸甲乙酯/碳酸二乙酯/氟代碳酸乙烯酯(体积比为1:1:1:1)的溶剂中，搅拌均匀，得到锂盐浓 度1mol/L的电解液。
5)隔离膜
以聚丙烯膜作为基膜，在基膜上涂1微米氧化铝和1微米聚偏氟乙烯。
6)电池的制备
将正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正、负极片之间起到隔离的作用，然后卷绕得到裸电芯，给裸电芯焊接极耳，并将裸电芯装入铝壳中，并在80℃下烘烤除水，随即注入电解液并封口，得到不带电的电池。不带电的电池再依次经过静置、热冷压、化成、整形、容量测试等工序，获得实施例1的锂电池产品。
实施例2～24
实施例2～24的电池与实施例1的电池制备方法相似，但是调整了正极活性材料的组分及其制备方法，具体参数如表1所示。
对比例1
对比例1的电池与实施例1的电池制备方法相似，但是共沉淀反应过程中不加入碳球的硬模板剂，制备方法具体如下：
对比例2～3
对比例2～3的电池与实施例1的电池制备方法相似，但是调整正极活性材料的制备方法的参数，具体参数如表1所示。
对比例4
对比例4与实施例21的电池制备方法相似，但是反应过程不加入碳球的硬模板剂，具体参数如表1所示。
对比例5～6
对比例5～6与实施例21的电池制备方法相似，但是调整正极活性材料的制备方法的参数，具体参数如表1所示。
二、性能测试
1、正极活性材料性能测试
1)中空结构的内径测试
将样品台上贴好导电胶，取各实施例和对比例中的正极活性材料的粉末状样品平铺于导电胶上，用洗耳球吹走未粘上的粉末，喷金，使用氩气等离子体对粉末状样品的颗粒进行截面切割。使用扫描电子显微镜(例如ZEISS Sigma 300)在加速电压为10kV，发射电流为10mA的条件下，得到粉末状样品的扫描电镜照片。根据SEM图片测量中空结构的内径尺寸，至少测量三个样品，每个样品至少测量50个数据，取数均平均值作为样品的中空结构的内径尺寸。
2)孔隙率测试
正极活性材料的孔隙率可以采用本领域公知的任意手段进行测试。作为示例，按照GB/T24586，采用气体置换法测量。孔隙率＝(V1-V2)/V1*100％，其中V1是样品的表观体积，V2是样品的真实体积。
3)中空结构的外壁厚度
将样品台上贴好导电胶，取各实施例和对比例中的正极活性材料的粉末状样品平铺于导电胶上，用洗耳球吹走未粘上的粉末，喷金，使用氩气等离子体对粉末状样品的颗粒进行截面切割。使用扫描电子显微镜(例如ZEISS Sigma 300)在加速电压为10kV，发射电流为10mA的条件下，得到粉末状样品的扫描电镜照片。根据SEM图片测量中空结构的外壁厚度，至少测量三个样品，每个样品至少测量50个数据，取数均平均值作为样品的中空结构的外壁厚度。
4)比表面积测试
参考GB/T 19587-2017《气体吸附BET法测定固态物质比表面积》。采用设备TriStar II 3020进行测定，将正极活性材料分散到分散剂中(乙醇)，超声30分钟后，将得到的材料放入真空干燥箱中干燥，最后使用比表面积测试仪对正极活性材料比表面积进行测量。
4)Dv50测试
参照GB/T 19077-2016粒度分布激光衍射法，用50mL烧杯称量0.1g～0.13g待测正极活性材料样品，加入5g无水乙醇，放入约 2.5mm搅拌子后用保鲜膜密封。样品超声处理5min后转移到磁力搅拌机，500转/分钟搅拌20min以上，每批次产品抽取2个样品测试。采用英国马尔文仪器有限公司的Mastersizer 2000E型激光粒度分析仪进行测试。其中，Dv50为正极活性材料的二次粒子累计体积分布百分数达到50％所对应的粒径。
5)SPAN测试
参照GB/T 19077-2016粒度分布激光衍射法，用50mL烧杯称量0.1g～0.13g待测正极活性材料样品，加入5g无水乙醇，放入约2.5mm搅拌子后用保鲜膜密封。样品超声处理5min后转移到磁力搅拌机，500转/分钟搅拌20min以上，每批次产品抽取2个样品测试。采用英国马尔文仪器有限公司的Mastersizer 2000E型激光粒度分析仪进行测试。其中，SPAN＝(Dv90-Dv10)/Dv50，二次粒子的Dv90为正极活性材料的二次粒子累计体积分布百分数达到90％所对应的粒径，二次粒子的Dv50为正极活性材料的二次粒子累计体积分布百分数达到50％所对应的粒径，二次粒子的Dv10为正极活性材料的二次粒子累计体积分布百分数达到10％所对应的粒径。
6)(101)晶面面积
采用X射线粉末衍射仪(XRD，仪器型号：Bruker D8ADVANCE)测试(101)晶面面积，靶材为Cu Kα；电压电流为40KV/40mA，扫描角度范围为5°至80°，扫描步长为0.00836°，每步长时间为0.3s。
7)一次颗粒粒径的测试方法
通过500倍的扫描电子显微镜(德国ZEISS Sigma-02-33)成像后，在其电子显微图像中随机选取200至600个形状完整且无遮档的正极活性材料的一次颗粒，并计录一次颗粒在显微图像中最长直径的平均值作为平均粒径。
2、电池性能测试
1)放电容量的测试
将电池单体在25℃静置2h，确保电池单体的温度为25℃。在 25℃下，以0.1C将电池单体充电至充电截止电压4.3V后，继续以该充电截止电压进行恒压充电，直至电流为0.02C，充电截止(其中，C表示电池单体额定容量)。将电池单体在25℃静置0.5h。在25℃下，以0.1C将电池单体放电至放电截止电压2.5V，记录电池单体放出的总放电容量C0。
2)能量密度测试
电池单体的容量测试：将电池单体在25℃静置2h，确保电池单体的温度为25℃。在25℃下，以0.1C将电池单体充电至充电截止电压后，继续以该充电截止电压进行恒压充电，直至电流为0.05C，充电截止(其中，C表示电池单体额定容量)。将电池单体在25℃静置1h。在25℃下，以0.1C将电池单体放电至放电截止电压，记录电池单体放出的总放电容量C0，总放电能量为E0。
电池单体重量测量：将电池单体放置在电子天平上至重量稳定，读取电池单体重量数值M0。
能量密度计算：电池单体放电能量E0/电池单体重量M0即为电池单体的能量密度。
3)10～80％SOC充电时间测试
电压标定：将电池相同设计的叠片三电极电芯25℃静置30min；在25℃下，以0.33C将电池单体充电至充电截止电压后，继续以该充电截止电压进行恒压充电，直至电流为0.05C，充电截止(其中，C表示电池单体额定容量)；25℃静置1h；在25℃下，以0.33C将电池单体放电至放电截止电压，记录电池单体放出的总放电容量C1；25℃静置1h。
充电测试：叠片三电极电芯25℃静置30min；0.33C1DC to放电截止电压；静置5min；xC1CC to充电截止电压(三电极监控阳极电位，阳极电位为0V时跳转下一步；重复上述步骤9次，x取值依次为5、4、4.5、3、2、1、0.8、0.5、0.33；取阳极电位为0V时对应的x数值和充电容量Cx。
4)电池循环容量保持率测试
将各实施例和对比例制备得到的二次电池以0.5C倍率恒流充电至充电截止电压4.25V，之后恒压充电至电流≤0.05C，静置5min，再以0.33C倍率恒流放电至放电截止电压2V，静置5min，此为一个充放电循环。按照此方法对电池进行循环充放电测试，直至电池容量衰减至80％。此时的循环圈数即为电池在25℃下的循环寿命。
三、各实施例、对比例测试结果分析
按照上述方法分别制备各实施例和对比例的电池，并测量各项性能参数，结果见下表1、表2和表3。
表1

表2

表3
根据上述结果，实施例1～24中的正极活性材料的化学式为LiNi0.97Co0.02Mn0.01O2、LiNi0.97Co0.03O2、LiNi0.995Co0.004Mn0.001O2、LiNi0.95Co0.04Mn0.01O2、LiNi0.97Co0.02Sb0.01O2中的任意一种。
采用扫描电子显微镜SEM进行实施例4中的正极活性材料的形貌测试，测试结果见图1，从图中可以看出正极活性材料为中空结构。实施例1～24中的正极活性材料的均具有中空结构，且中空结构的内径d1为0.3μm-5μm。
从实施例1～20与对比例1，实施例21与对比例4对比可见，正极活性材料具有中空结构，可以提高电池的放电容量和能量密度，缩短电池的充电时间，提高电池的倍率性能，提高电池的循环性能。
从实施例1～20与对比例2～3，实施例21与对比例5～6对比可见，中空结构的内径d1为0.3μm-5μm，可以提高电池的循环性能，同时电池具有高的放电容量和能量密度，具有优异的倍率性能，综合改善电池的电化学性能。
从实施例2～4、6～20与实施例1、5对比可见，中空结构的内径d1为1.5μm-5μm，可以进一步提高电池的循环性能和倍率性能。
从实施例4、7、11～16与实施例9～10对比可见，通过控制正极活性材料的Dv50与中空结构的内径d1和外壁厚度d2满足：1≤Dv50/(d1+d2)≤4，可以提高电池的能量密度，改善电池的倍率性能。
从实施例1～24中可见，中空结构的外壁壁厚d2为3μm-10μm，电池具有高的放电容量和能量密度，具有优异的倍率性能和循环性能，综合改善电池的电化学性能。从实施例2～4、6～20与实施例1、5对比可见，中空结构的外壁厚度d2为3μm-7μm，可以进一步提高电池的循环性能和倍率性能。
从实施例4、7、10～16与实施例9对比可见，正极活性材料的Dv50为5μm-15μm，可以提高电池的能量密度和倍率性能。从实施例4、7、11～16与实施例9～10对比可见，正极活性材料的Dv50为8μm-10μm，可以进一步提高电池的能量密度和倍率性能。
从实施例1～24中可见，正极活性材料的孔隙率为0-20％，电池具有高的放电容量和能量密度，具有优异的倍率性能和循环性能，综合改善电池的电化学性能。从实施例2～4、6～8、13～16与实施例1、5对比可见，正极活性材料的孔隙率为2％-15％，能够提高电池的放电容量和能量密度，改善电池的倍率性能和循环性能。
从实施例1～24中可见，正极活性材料的比表面积为0.4m2/g-1.4m2/g，电池具有高的放电容量和能量密度，具有优异的倍率性能和循环性能，综合改善电池的电化学性能
从实施例4、15～16与实施例13～14对比可见，正极活性材料的SPAN为1-1.5，可以提高电池的放电容量。从实施例4、15与实施例13～14、16对比可见，正极活性材料的SPAN为1.2-1.4，可以兼顾电池的循环性能和倍率性能，综合改善电池的电化学性能。
从实施例1～24中可见，正极活性材料的(010)晶面面积大于等于6μm2，电池具有高的放电容量和能量密度，具有优异的倍率性能和循环性能，综合改善电池的电化学性能。
从实施例17～19与实施例20对比可见，正极活性材料的一次颗粒粒径为0.1-0.8μm，可以提高电池的放电容量和能量密度，改善电池的倍率性能。从实施例18～19与实施例17、20对比可见，正极活性材料的一次颗粒粒径为0.15-0.3μm，可以改善电池的循环性能。

Claims (25)

  1. 一种正极活性材料，其特征在于，所述正极活性材料的化学式为LiaNixCoyM1-x-yO2，
    其中，M包括Mn、Al、B、Zr、Sr、Y、Sb、W、Ti、Mg、Nb中的一种或多种，0.55≤x≤1.0，0≤y≤0.45，0.8≤a≤1.2，且所述正极活性材料为中空结构，所述中空结构的内径d1为0.3μm-5μm。
  2. 根据权利要求1所述的正极活性材料，其特征在于，所述化学式LiaNixCoyM1-x-yO2中，0.9≤x≤1.0，0≤y≤0.1，0.8≤a≤1.2，可选地0.95≤x≤0.995，0≤y≤0.05，0.8≤a≤1.2。
  3. 根据权利要求1或2所述的正极活性材料，其特征在于，所述中空结构的内径d1为1.5μm-5μm。
  4. 根据权利要求1至3中任一项所述的正极活性材料，其特征在于，所述正极活性材料满足如下关系式：1≤Dv50/(d1+d2)≤4，
    其中d1μm为所述中空结构的内径，d2μm为所述中空结构的外壁厚度，Dv50μm为所述正极活性材料的Dv50。
  5. 根据权利要求1至4中任一项所述的正极活性材料，其特征在于，所述中空结构的外壁壁厚d2为3μm-10μm，可选为3μm-7μm。
  6. 根据权利要求1至5中任一项所述的正极活性材料，其特征在于，所述正极活性材料的Dv50为5μm-15μm，可选为8μm-10μm。
  7. 根据权利要求1至6中任一项所述的正极活性材料，其特征在于，所述正极活性材料的孔隙率为0-20％，可选为2％-15％。
  8. 根据权利要求1至7中任一项所述的正极活性材料，其特征在于，所述正极活性材料的比表面积为0.4m2/g-1.4m2/g。
  9. 根据权利要求1至8中任一项所述的正极活性材料，其特征在于，所述正极活性材料的SPAN为1-1.5，可选为1.2-1.4。
  10. 根据权利要求1至9中任一项所述的正极活性材料，其特征在于，所述正极活性材料的(010)晶面面积大于等于6μm2。
  11. 根据权利要求1至10中任一项所述的正极活性材料，其特征在于，所述正极活性材料的一次颗粒粒径为0.1-0.8μm，可选为0.15-0.3μm。
  12. 一种正极活性材料的制备方法，其特征在于，包括步骤(1)和步骤(2)：
    步骤(1)：将包含镍源、钴源的混合源与硬模板剂、络合剂、沉淀剂混合，进行共沉淀反应，得到前驱体，可选地，所述混合源中含有M源
    步骤(2)：将前驱体与锂源煅烧得到正极活性材料，
    所述正极活性材料的化学式为LiaNixCoyM1-x-yO2，
    其中，M包括Mn、Al、B、Zr、Sr、Y、Sb、W、Ti、Mg、Nb中的一种或多种，0.55≤x≤1.0，0≤y≤0.45，0.8≤a≤1.2，所述正极活性材料为中空结构，所述中空结构的内径为0.3μm～5μm。
  13. 根据权利要求12所述的制备方法，其特征在于，所述化学式LiaNixCoyM1-x-yO2中，0.9≤x≤1.0，0≤y≤0.1，0.8≤a≤1.2，可选地0.95≤x≤0.995，0≤y≤0.05，0.8≤a≤1.2。
  14. 根据权利要求12或13所述的制备方法，其特征在于，所述硬模板剂的平均直径为0.2μm-3μm，可选为1μm-3μm。
  15. 根据权利要求12至14中任一项所述的制备方法，其特征在于，所述硬模板剂包括碳氮复合球、碳球、酚醛树脂微球、密胺树脂微球中的一种或多种，可选地包括酚醛树脂球。
  16. 根据权利要求12至15中任一项所述的制备方法，其特征在于，所述步骤(1)中投入的所述硬模板剂的重量和所述混合源中的镍元素和钴元素总重量之比为1:20-3:4，
    或者所述步骤(1)中投入的所述硬模板剂的重量和所述混合源中的镍元素、钴元素和M元素总重量之比为1:20-3:4。
  17. 根据权利要求12至16中任一项所述的制备方法，其特征在于，所述步骤(1)中的共沉淀反应的pH值为9-13。
  18. 根据权利要求12至17中任一项所述的制备方法，其特征在于，所述步骤(1)中共沉淀反应的反应温度为60-85℃。
  19. 根据权利要求12至18中任一项所述的制备方法，其特征在于，所述步骤(1)中共沉淀反应的反应时间为5-20h。
  20. 根据权利要求12至19中任一项所述的制备方法，其特征在于，所述步骤(1)中共沉淀反应搅拌的速度为200-900rpm。
  21. 根据权利要求12至20中任一项所述的制备方法，其特征在于，所述步骤(1)具体包括：
    配制质量浓度为1-10g/L的硬模板剂溶液、摩尔浓度为1-2mol/L的沉淀剂溶液、摩尔浓度为4-8mol/L的络合剂溶液、包含 镍元素、钴元素总摩尔浓度为1-2mol/L的混合盐溶液，可选的所述混合盐溶液还包含M元素；
    将所述沉淀剂溶液、所述络合剂溶液及所述混合盐溶液合流加至所述硬模板剂溶液中；
    进行所述共沉淀反应，得到所述前驱体。
  22. 根据权利要求12至21中任一项所述的制备方法，其特征在于，所述步骤(2)中的所述煅烧温度为700-900℃；
    所述步骤(2)中的所述煅烧时间为6-18h。
  23. 一种正极极片，其特征在于，所述正极极片包括权利要求1至10中任一项所述的正极活性材料或权利要求12至22中任一项所述的制备方法制备的正极活性材料。
  24. 一种二次电池，其特征在于，包括权利要求23所述的正极极片。
  25. 一种用电装置，其特征在于，包括权利要求24所述的二次电池。
PCT/CN2023/085514 2023-03-31 2023-03-31 正极活性材料、及其制备方法、正极极片、二次电池和用电装置 Ceased WO2024197826A1 (zh)

Priority Applications (5)

Application Number Priority Date Filing Date Title
EP23929411.9A EP4614617A4 (en) 2023-03-31 2023-03-31 ACTIVE POSITIVE ELECTRODE MATERIAL, ITS PREPARATION PROCESS, POSITIVE ELECTRODE SHEET, SECONDARY BATTERY AND ELECTRICAL APPLIANCE
CN202511932716.XA CN121416492A (zh) 2023-03-31 2023-03-31 正极活性材料、及其制备方法、正极极片、二次电池和用电装置
CN202380044727.7A CN119452483B (zh) 2023-03-31 2023-03-31 正极活性材料、及其制备方法、正极极片、二次电池和用电装置
PCT/CN2023/085514 WO2024197826A1 (zh) 2023-03-31 2023-03-31 正极活性材料、及其制备方法、正极极片、二次电池和用电装置
US19/210,483 US20250276913A1 (en) 2023-03-31 2025-05-16 Positive electrode active material, preparation method therefor, positive electrode sheet, secondary battery and electrical apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2023/085514 WO2024197826A1 (zh) 2023-03-31 2023-03-31 正极活性材料、及其制备方法、正极极片、二次电池和用电装置

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US19/210,483 Continuation US20250276913A1 (en) 2023-03-31 2025-05-16 Positive electrode active material, preparation method therefor, positive electrode sheet, secondary battery and electrical apparatus

Publications (1)

Publication Number Publication Date
WO2024197826A1 true WO2024197826A1 (zh) 2024-10-03

Family

ID=92903037

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2023/085514 Ceased WO2024197826A1 (zh) 2023-03-31 2023-03-31 正极活性材料、及其制备方法、正极极片、二次电池和用电装置

Country Status (4)

Country Link
US (1) US20250276913A1 (zh)
EP (1) EP4614617A4 (zh)
CN (2) CN119452483B (zh)
WO (1) WO2024197826A1 (zh)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN120184230A (zh) * 2025-05-23 2025-06-20 浙江绿色智行科创有限公司 三元正极材料及其制备方法、正极和电池

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20190038490A (ko) * 2018-02-13 2019-04-08 한국교통대학교산학협력단 공침법으로 합성한 중공 구조를 갖는 양극 활물질, 이의 제조방법 및 이를 이용한 리튬 이차전지
CN111498915A (zh) * 2020-04-26 2020-08-07 株洲升华科技有限公司 正极材料及其制备方法和锂离子电池
CN111689528A (zh) * 2020-07-10 2020-09-22 湖北亿纬动力有限公司 一种三元材料前驱体及其制备方法和用途
CN112086616A (zh) * 2020-10-19 2020-12-15 四川工程职业技术学院 一种大(010)晶面镍钴锰/铝层状正极材料的制备方法
CN112768685A (zh) * 2021-04-09 2021-05-07 湖南长远锂科股份有限公司 一种长循环、高功率的锂离子电池正极材料及其制备方法
CN113830844A (zh) * 2021-09-28 2021-12-24 蜂巢能源科技有限公司 空心多孔三元正极材料及其制备方法、锂离子电池
CN115020697A (zh) * 2022-06-13 2022-09-06 北京当升材料科技股份有限公司 一种正极材料及其制备方法及应用

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101419982B1 (ko) * 2011-06-22 2014-07-15 울산대학교 산학협력단 균일한 중공형의 리튬이차전지용 양극 활물질의 제조방법

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20190038490A (ko) * 2018-02-13 2019-04-08 한국교통대학교산학협력단 공침법으로 합성한 중공 구조를 갖는 양극 활물질, 이의 제조방법 및 이를 이용한 리튬 이차전지
CN111498915A (zh) * 2020-04-26 2020-08-07 株洲升华科技有限公司 正极材料及其制备方法和锂离子电池
CN111689528A (zh) * 2020-07-10 2020-09-22 湖北亿纬动力有限公司 一种三元材料前驱体及其制备方法和用途
CN112086616A (zh) * 2020-10-19 2020-12-15 四川工程职业技术学院 一种大(010)晶面镍钴锰/铝层状正极材料的制备方法
CN112768685A (zh) * 2021-04-09 2021-05-07 湖南长远锂科股份有限公司 一种长循环、高功率的锂离子电池正极材料及其制备方法
CN113830844A (zh) * 2021-09-28 2021-12-24 蜂巢能源科技有限公司 空心多孔三元正极材料及其制备方法、锂离子电池
CN115020697A (zh) * 2022-06-13 2022-09-06 北京当升材料科技股份有限公司 一种正极材料及其制备方法及应用

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP4614617A4 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN120184230A (zh) * 2025-05-23 2025-06-20 浙江绿色智行科创有限公司 三元正极材料及其制备方法、正极和电池
CN120184230B (zh) * 2025-05-23 2025-09-16 浙江绿色智行科创有限公司 三元正极材料及其制备方法、正极和电池

Also Published As

Publication number Publication date
EP4614617A4 (en) 2026-03-04
CN119452483B (zh) 2026-01-23
EP4614617A1 (en) 2025-09-10
US20250276913A1 (en) 2025-09-04
CN121416492A (zh) 2026-01-27
CN119452483A (zh) 2025-02-14

Similar Documents

Publication Publication Date Title
EP4207372A1 (en) Secondary battery and electric device
CN114975980A (zh) 负极材料及使用其的电化学装置和电子装置
WO2020143531A1 (zh) 正极活性材料及其制备方法、钠离子电池和包含钠离子电池的装置
CN115832236B (zh) 磷酸铁锂正极材料、其制备方法、正极极片、锂离子电池、电池模块、电池包和用电装置
CN117117357B (zh) 补锂剂及其制备方法、正极极片、电池、用电装置
WO2023124913A1 (zh) 负极活性材料、其制备方法及其相关的二次电池和装置
WO2024020795A1 (zh) 一种复合正极材料、其制备方法、二次电池、电池模块、电池包和用电装置
WO2023044866A1 (zh) 硅碳负极材料、负极极片、二次电池、电池模块、电池包和用电装置
WO2023164931A1 (zh) 正极极片、二次电池、电池模块、电池包和用电装置
US20250276913A1 (en) Positive electrode active material, preparation method therefor, positive electrode sheet, secondary battery and electrical apparatus
WO2024077522A1 (zh) 负极活性材料的制备方法、负极活性材料、二次电池和用电装置
CN118851282B (zh) 正极活性材料、及其制备方法、正极极片、二次电池和用电装置
CN118851283B (zh) 正极活性材料、正极极片、二次电池和用电装置
CN118369787B (zh) 负极活性材料及其制备方法、二次电池、电池模块、电池包和用电装置
CN115832219B (zh) 一种复合材料、正极极片及二次电池
WO2025194671A1 (zh) 二次电池和用电装置
WO2025050668A1 (zh) 硅复合材料及其制备方法、负极极片、二次电池和用电装置
WO2026026183A1 (zh) 正极材料及其制备方法、二次电池、用电装置
WO2025082088A1 (zh) 锂二次电池用正极材料及其制备方法、正极极片、二次电池及其使用方法、用电装置
WO2025161390A1 (zh) 正极极片及其制备方法、电池单体、电池和用电装置
WO2025167103A1 (zh) 钠二次电池、正极极片、补钠添加剂和用电装置
WO2024050830A1 (zh) 尖晶石型含锂锰复合氧化物及其制备方法、正极极片、二次电池及用电装置
WO2025112398A1 (zh) 前驱体材料及其制备方法、正极材料及其制备方法、正极极片、电池及用电装置
WO2024087013A1 (zh) 电极组件、电池单体、电池和用电装置
WO2024197866A1 (zh) 正极活性材料、正极极片、二次电池及用电装置

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 23929411

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 202380044727.7

Country of ref document: CN

WWP Wipo information: published in national office

Ref document number: 202380044727.7

Country of ref document: CN

WWE Wipo information: entry into national phase

Ref document number: 2023929411

Country of ref document: EP

ENP Entry into the national phase

Ref document number: 2023929411

Country of ref document: EP

Effective date: 20250605

WWP Wipo information: published in national office

Ref document number: 2023929411

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: DE