WO2024113430A1 - 一种正极活性材料及锂离子电池 - Google Patents

一种正极活性材料及锂离子电池 Download PDF

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WO2024113430A1
WO2024113430A1 PCT/CN2022/139467 CN2022139467W WO2024113430A1 WO 2024113430 A1 WO2024113430 A1 WO 2024113430A1 CN 2022139467 W CN2022139467 W CN 2022139467W WO 2024113430 A1 WO2024113430 A1 WO 2024113430A1
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positive electrode
active material
electrode active
peak
fwhw
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French (fr)
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欧阳云鹏
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Sunwoda Mobility Energy Technology Co Ltd
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Sunwoda Mobility Energy Technology Co Ltd
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Priority to JP2024529686A priority Critical patent/JP2025501057A/ja
Priority to EP22967015.3A priority patent/EP4496031A4/en
Priority to US18/865,695 priority patent/US20250357480A1/en
Publication of WO2024113430A1 publication Critical patent/WO2024113430A1/zh
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—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
    • 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
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/74—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by peak-intensities or a ratio thereof only
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to a positive electrode active material and a lithium ion battery, belonging to the technical field of secondary batteries.
  • a lithium ion battery prepared using the positive electrode active material can reduce the dissolution of transition metals in the positive electrode active material in the lithium ion battery, reduce the interaction between the fresh interface of the slip crack and the electrolyte, and improve the charging capacity, cycle life and safety performance of the secondary battery.
  • the positive electrode active material provided in the present application includes lithium nickel cobalt manganese oxide
  • the molar amount of the manganese element is recorded as m%
  • the molar amount of the cobalt element is recorded as n%
  • the following conditions are satisfied: 20 ⁇ n+m ⁇ 50, and 0.1 ⁇ n/m ⁇ 0.6
  • the half-peak width of the (003) peak of the positive electrode active material is recorded as FWHW(003)
  • the half-peak width of the (104) peak of the positive electrode active material is recorded as FWHW(104)
  • the FWHW(003) and the FWHW (104) satisfy the following conditions: 0.4 ⁇ FWHW(003)/FWHW(104) ⁇ 2.0.
  • the molar contents of the manganese element and the cobalt element satisfy any one of the following conditions:
  • the positive electrode active material further includes an M element, wherein the M element includes Zr and at least one of Al, Mg, Ti, Y, Sr, Y, Mo, Nb, Sn, Ba, La, and Ce elements;
  • the percentage of the molar amount of the M element to the total molar amount of the nickel element, the cobalt element and the manganese element is recorded as x%, and 0.1 ⁇ x ⁇ 2.5.
  • the M element includes Zr element, Al element, and at least one of Mg, Ti, Y, Sr, Y, Mo, Nb, Sn, Ba, La, Ce, and W elements, the molar content of the M element is x%, the molar content of Zr is x1%, and the molar content of Al is x2%, and x, x1, and x2 satisfy any one of the following conditions:
  • the half-peak width of the (003) peak of the positive electrode active material of the present application is recorded as FWHW(003), and the half-peak width of the (104) peak of the positive electrode active material is recorded as FWHW(104);
  • the FWHW(003) ranges from 0.06 to 0.15°;
  • the FWHW (104) is in the range of 0.06 to 0.15°.
  • the peak area of the (003) peak of the positive electrode active material of the present application is recorded as Ic(003)
  • the peak area of the (104) peak is recorded as Ic(104)
  • Kc is Ic(003)/Ic(104), 1 ⁇ Kc ⁇ 2.
  • the positive electrode active material of the present application comprises Li a Ni b Co m/100 Mn n/100 M x/100 O 2 , 0.80 ⁇ a ⁇ 1.10, 0.4 ⁇ b ⁇ 0.8, 20 ⁇ n+m ⁇ 50, and 0.1 ⁇ n/m ⁇ 0.6, 0.1 ⁇ x ⁇ 2.5, M comprises Zr, and at least one of Al, Mg, Ti, Y, Sr, Y, Mo, Nb, Sn, Ba, La, Ce and W.
  • the present application also provides a secondary battery, comprising a positive electrode; the positive electrode comprises a positive electrode current collector and a positive electrode mixture layer disposed on the positive electrode current collector, the positive electrode mixture layer being made of the positive electrode active material;
  • the peak area of the (003) peak of the positive electrode mixture layer is recorded as If(003)
  • the peak area of the (104) peak is recorded as If(104)
  • Kf is If(003)/If(104)
  • the proportion of the number of particles of the positive electrode active material in the positive electrode mixture layer having a size of 1 micron to 3 microns to the total number of particles is greater than 60%;
  • the uniformity of the particle size of the positive electrode active material in the positive electrode mixture layer has a significant impact on the charging performance of the battery.
  • the positive electrode active material provided in the present application includes lithium nickel cobalt manganese oxide
  • the molar amount of the manganese element is recorded as m%
  • the molar amount of the cobalt element is recorded as n%
  • the following conditions are satisfied: 20 ⁇ n+m ⁇ 50, and 0.1 ⁇ n/m ⁇ 0.6
  • the half-peak width of the (003) peak of the positive electrode active material is recorded as FWHW(003)
  • the half-peak width of the (104) peak of the positive electrode active material is recorded as FWHW(104)
  • the FWHW(003) and the FWHW(104) satisfy the following conditions: 0.4 ⁇ FWHW(003)/FWHW(104) ⁇ 2.0.
  • the value of FWHW(003)/FWHW(104) can be any value of 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.99, 1.0, 1.1, 1.3, 1.5, 1.8, 2.0, or a range consisting of any two of these values.
  • the half-peak width of the (003) peak of the positive electrode active material is recorded as FWHW(003)
  • the half-peak width of the (104) peak of the positive electrode active material is recorded as FWHW(104)
  • 0.4 ⁇ FWHW(003)/FWHW(104) ⁇ 1.5 When the FWHW(003)/FWHW(104) of the positive electrode active material is within the above range, the stability of the crystal structure of the positive electrode active material is high, and the charging capacity, cycle life and safety performance of the secondary battery are improved.
  • FWHW(003)/FWHW(104) When FWHW(003)/FWHW(104) is within the above range, it indicates that the residual stress inside the lattice of the positive electrode active material particles is low or the mixing rate of lithium ions and transition metal ions is low.
  • the residual stress inside the lattice or the mixing of ions will cause the atoms in the lattice to deviate from the equilibrium position, resulting in a higher value of FWHW(003) or FWHW(104), resulting in a change in the ratio of FWHW(003)/FWHW(104).
  • the residual stress inside the lattice or the mixing of ions will increase the barrier for lithium ions to escape from the positive electrode active material, reducing the charging capacity of the battery.
  • manganese and cobalt elements can stabilize the stability of the structure of lithium nickel cobalt manganese oxide during the lithium removal process, and have a supporting effect on the material structure.
  • the manganese and cobalt elements are too high, the proportion of nickel elements participating in the electrochemical reaction is reduced, which leads to a decrease in the energy density of lithium nickel cobalt manganese oxide.
  • Nickel and manganese elements are easy to migrate to the tetrahedral vacancies in the lattice during the charging process, causing the lattice of the positive electrode active material to be distorted, destroying the stability of the material lattice, and at the same time, the nickel ions and manganese ions in the tetrahedral vacancies will also migrate and dissolve in the electrolyte under the action of the electric field, and the dissolved nickel ions and manganese ions (especially manganese ions) are easy to be reduced at the negative electrode, destroying the surface protective film of the negative electrode, resulting in an increase in impedance, improving the risk of lithium precipitation, and reducing the charging capacity, cycle life and safety performance of the battery.
  • the presence of cobalt in the positive electrode active material can inhibit the migration of nickel ions and manganese ions to the tetrahedral vacancies in the lattice during the charging process, but when the cobalt content is high, the capacity of the positive electrode active material will be reduced. At the same time, cobalt is a scarce metal in the earth's crust, and excessive cobalt content will also increase the cost of the positive electrode active material.
  • the above problems can be effectively improved by controlling the content of nickel, cobalt and manganese elements, as well as the stability of the formed positive electrode active material crystals.
  • m can be any value among any value of 19, 20, 21, 23, 25, 27, 27.5, 28, 30, 32, 33, 34, 37, 39, 40, 42, 43.5, or a range consisting of any two values therein.
  • the crystal structure of the positive electrode active material can be further optimized, making the positive electrode active material more stable.
  • n can be any value of 3, 4.5, 5, 7, 8, 9, 10, 11, 12, 14, or a range consisting of any two values thereof.
  • 0.10 ⁇ n/m ⁇ 0.502. it can be any value among 0.10, 0.15, 0.18, 0.20, 0.22, 0.25, 0.28, 0.30, 0.32, 0.35, 0.38, 0.40, 0.42, 0.45, 0.48, 0.502 or a range of any two values thereof.
  • n/m is within this range, the crystal structure of the positive electrode active material can be further controlled to make the performance of the secondary battery better.
  • the positive electrode active material further includes an M element
  • the M element includes at least one of Zr, Al, Mg, Ti, Y, Sr, Y, Mo, Nb, Sn, Ba, La, Ce, and W.
  • Suitable M elements can form chemical bonds with oxygen in lithium nickel cobalt manganese oxide, and can improve the stability of the metal and oxygen octahedral structure in lithium nickel cobalt manganese oxide.
  • reducing the precipitation of transition metals on the negative electrode sheet and the release of lattice oxygen in the positive electrode active material will lead to safety risks.
  • the M element includes Zr and at least one of Al, Mg, Ti, Y, Sr, Y, Mo, Nb, Sn, Ba, La, and Ce. Since the bond energy of the chemical bond formed by the Zr element with oxygen is much greater than the chemical energy formed by the nickel, cobalt, and manganese elements with oxygen, the addition of the M element including Zr can further improve the stability of the metal and oxygen octahedral structure in the lithium nickel cobalt manganese oxide.
  • the M element includes the W element and at least one of the Zr, Al, Mg, Ti, Y, Sr, Y, Mo, Nb, Sn, Ba, La, and Ce elements.
  • the M element includes Zr and Al, and at least one of Mg, Ti, Y, Sr, Y, Mo, Nb, Sn, Ba, La, Ce, and W.
  • the bond energy of the chemical bond formed by the Al element and the oxygen in the lithium nickel cobalt manganese oxide in the positive electrode active material is smaller than that of the Zr element, but the Al element is beneficial to improve the migration energy of the nickel ions in the lithium nickel cobalt manganese oxide to the position of the lattice lithium after bonding, reduce the proportion of nickel ions at the position of the lattice lithium, increase the lithium ion migration rate, and further reduce the charging capacity of the battery.
  • the M element includes Zr element and W element, and at least one of Al, Mg, Ti, Y, Sr, Y, Mo, Nb, Sn, Ba, La, and Ce elements.
  • the total molar amount of the nickel element, the cobalt element and the manganese element is 100%, and the ratio of the molar amount of the M element to the total molar amount of the nickel element, the cobalt element and the manganese element is recorded as x%, 0.1 ⁇ x ⁇ 2.5.
  • x can be any value of 0.1, 0.3, 0.5, 0.7, 0.9, 1.0, 1.1, 1.3, 1.5, 1.7, 1.9, 2.0, 2.2, 2.4, 2.5 or a range consisting of any two values thereof.
  • 0.2 ⁇ x ⁇ 1.5 Because the transition metals nickel and manganese will be dissolved in lithium nickel cobalt manganese oxide when the battery is fast charged, the structural stability of the positive electrode active material will be reduced, and the protective film on the surface of the negative electrode plate will be damaged, thereby reducing the charging capacity and service life of the battery. The precipitation of transition metals on the negative electrode side and the release of lattice oxygen will lead to safety risks.
  • the content of the M element is within the above range, it can ensure the structural stability of the positive electrode active material while reducing the impact on the available capacity of the positive electrode active material, so that the battery can have high capacity, excellent charging capacity, service life and safety performance.
  • the M element includes Zr element and Al element, and at least one of Mg, Ti, Y, Sr, Y, Mo, Nb, Sn, Ba, La, Ce, and W elements; wherein the molar content of the M element is recorded as x%, the molar content of Zr is recorded as x1%, and the molar content of Al is recorded as x2%.
  • x1 can be any value among 0.20, 0.22, 0.24, 0.25, 0.27, 0.29, 0.30, 0.32, 0.34, 0.36, 0.39, 0.40, 0.42, 0.44, 0.45, or a range consisting of any two values thereof.
  • the addition of the Zr element can effectively reduce metal dissolution and lattice oxygen release, thereby improving the charging capacity, service life, and safety performance of the battery.
  • x2 can be any value in 0.15, 0.20, 0.25, 0.3, 0.32, 0.35, 0.37, 0.40, 0.45, 0.47, 0.50, 0.53, 0.57, 0.59, 0.60, 0.63, 0.65, 0.68, 0.70, 0.73, 0.75, 0.78, 0.80, 0.85, 0.90, 0.93, 0.95, 1.0, 1.2, 1.5, or a range consisting of any two values thereof.
  • x1/x2 can be any value among 0.20, 0.25, 0.3, 0.32, 0.35, 0.37, 0.40, 0.45, 0.47, 0.50, 0.53, 0.57, 0.59, 0.60, 0, 63, 0.65, 0.68, 0.70, 0.73, 0.75, 0.78, 0.80, 0.85, 0.90, 0.93, 0.95, 1.0, or a range value composed of any two values therein.
  • the content of the Al element is controlled to be greater than or equal to the content of the Zr element, and the ratio of the two is within the above range, the proportion of lattice lithium in the positive electrode active material and the stability of the crystal structure can be made, so that the crystal structure of the positive electrode active material is in a more optimal state, and the overall performance of the battery is further improved.
  • (x-x1-x2)/x can be any value among 0.001, 0.05, 0.1, 0.13, 0.15, 0.18, 0.20, 0.25, 0.3, 0.32, 0.35, 0.37, 0.40, 0.45, 0.47, 0.50, or a range value consisting of any two values therein.
  • the crystal structure of the positive electrode active material can be further optimized, so that the battery has better comprehensive performance.
  • the half-peak width of the (003) peak of the positive electrode active material is recorded as FWHW(003), and the range of FWHW(003) is 0.06-0.15°.
  • FWHW(003) can be any value among 0.06°, 0.07°, 0.09°, 0.10°, 0.12°, 0.14°, 0.15°, or a range consisting of any two values therein.
  • the half-peak width of the (104) peak of the positive electrode active material is recorded as FWHW(104), and the range of FWHW(104) is 0.06-0.15°.
  • FWHW(104) can be any value among 0.06°, 0.07°, 0.09°, 0.10°, 0.12°, 0.14°, 0.15°, or a range consisting of any two values therein.
  • the half-peak width FWHW of the characteristic peak of the positive electrode active material represents the peak width at half the height of the characteristic peak after deducting the background and K ⁇ 2 of the XRD curve, and the unit is °.
  • the scanning speed of XRD is 2°/min.
  • the half-peak width FWHM of the characteristic peak (003) and the characteristic peak (104) is less than 0.15°, it indicates that the crystal form of the positive electrode active material is complete and the crystallinity is good; if the half-peak width FWHM of the characteristic peak (003) and the characteristic peak (104) is greater than 0.15°, it indicates that the positions of some atoms in the positive electrode active material deviate from the positions of the ideal crystal, indicating that the crystallinity of the material is poor, which will lead to the service life of the material.
  • the half-peak width FWHM is less than 0.06°, it indicates that the positive electrode active material not only has good crystallinity, but also has a larger grain size.
  • the half-peak widths of the characteristic peaks of the positive electrode active materials (003) and (104) should be within an appropriate range to ensure that the battery has a good service life and charging capacity.
  • the FWHW(003) ranges from 0.07 to 0.098°.
  • the FWHW(003) ranges from 0.09 to 0.12°.
  • the peak area of the (003) peak of the positive electrode active material is recorded as Ic(003)
  • the peak area of the (104) peak is recorded as Ic(104)
  • Kc is Ic(003)/Ic(104)
  • 1 ⁇ Kc ⁇ 2 Kc can be any value of 1, 1.1, 1.2, 1.3, 1.35, 1.4, 1.45, 1.48, 1.5, 1.52, 1.54, 1.56, 1.58, 1.6, 1.63, 1.65, 1.67, 1.7, 1.73, 1.75, 1.78, 1.8, 1.85, 1.9, 2.0, or a range consisting of any two values thereof.
  • Kc can reflect the crystallinity of the positive electrode active material.
  • the Kc value of the positive electrode active material is between 1.0 and 2.0, it indicates that the positive electrode active material has good crystallinity and few defects inside the material.
  • Kc is lower than 1.0, the crystallinity of the positive electrode active material is poor, and there are many defects inside, which will affect the structural stability of the positive electrode active material. When used, it may lead to low battery capacity, hinder the release of lithium ions, and affect the fast charging ability and long-term life of the material.
  • the positive electrode active material of the present application can be prepared by the following method:
  • the precursor Ni b Co m/100 Mn n/100 (OH) 2 , lithium salt, and additive A1 containing the added metal element M1 are placed in a mixing device for thorough mixing.
  • the ratio of lithium in the lithium salt to the ternary material precursor Ni b Co m/100 Mn n/100 (OH) 2 is a: 1.95 ⁇ a ⁇ 1.2.
  • the lithium salt can be lithium carbonate, lithium hydroxide or other compounds that can provide lithium elements.
  • M1 can be selected from one or more of Mg, Al, Ti, Y, Sr, Zr, Mo, Nb, Sn, Ba, La, and Ce.
  • M1 contains at least Zr element.
  • Additive A1 is an oxide, hydroxide or other compound containing the added element M1.
  • the mixed materials are loaded into a sagger and placed in an atmosphere furnace for sintering.
  • the temperature of the heating zone is between 25°C and 950°C
  • the sintering temperature of the constant temperature zone is between 800°C and 1000°C
  • the total sintering time of the heating zone and the constant temperature zone is 15 to 40 hours
  • pure oxygen is introduced during the sintering process to ensure that the oxygen concentration in the kiln is 20% to 99%.
  • the ratio Kc of the characteristic peak Ic(003)/Ic(104) of the positive electrode active material, the half-peak width of the characteristic peaks of the positive electrode active material (003) and (104), the ratio of the half-peak width of the characteristic peaks of the positive electrode active material (003) and (104), and the particle size and uniformity of the positive electrode active material can be controlled.
  • the positive electrode active material obtained after sintering is subjected to roller and air flow crushing.
  • the parameters of air flow crushing such as the diameter of the air inlet nozzle, feeding frequency, induced draft frequency, air pressure, silo material weight and other parameters, the size distribution of the positive electrode active material particles can be adjusted.
  • M2 can be selected from one or more of Mg, Al, Ti, Y, Sr, Zr, Mo, Nb, Sn, Ba, La, and Ce, and the additive A2 is an oxide, hydroxide or other compound containing the added element M2.
  • the mixed positive electrode active material and additive mixture is placed in a kiln for secondary sintering to obtain the finished positive electrode active material.
  • the sintering temperature is 350-850°C and the sintering time is 5-20 hours.
  • the secondary sintering can repair the surface of the positive electrode particles damaged during the crushing process, reduce the residual alkali of the material, and form a protective layer with a certain thickness on the surface.
  • the present application also provides a secondary battery, comprising a positive electrode; the positive electrode comprises a positive electrode current collector and a positive electrode mixture layer disposed on the positive electrode current collector, the positive electrode mixture layer being made of the positive electrode active material;
  • the peak area of the (003) peak of the positive electrode mixture layer is recorded as If(003)
  • the peak area of the (104) peak is recorded as If(104)
  • Kf is If(003)/If(104)
  • 10 ⁇ Kf ⁇ 20 Kf can be any value of 10, 11, 12, 13, 13.3, 13.5, 13.7, 14, 14.5, 14.7, 15, 15.3, 15.5, 15.7, 16, 16.3, 16.5, 16.7, 17, 17.5, 18, 19, 20, or a range of any two values thereof.
  • the Kf ratio reflects the preferred orientation of the positive electrode active material in the positive electrode mixture layer.
  • the ratio is ⁇ 20, it indicates that the preferred orientation is more serious, that is, it means that the crystal plane of the positive electrode active material has undergone significant slip during the preparation process of the positive electrode mixture layer. This slip will cause cracks on the surface of the positive electrode particles, resulting in poor stability of the material, easy metal dissolution and side reactions with the interface.
  • the larger the Kf the closer the angle between the lithium ion escape direction and the electric field direction is to 90°, which is not conducive to the escape of lithium ions and reduces the charging capacity of the battery.
  • the bonding effect between the positive electrode powder and the conductive agent is poor, resulting in a higher internal resistance of the battery.
  • the ohmic polarization of the lithium ion battery is large, which reduces the charging capacity of the battery.
  • 13 ⁇ Kf ⁇ 17 13 ⁇ Kf ⁇ 17.
  • Kf is within this range, the orientation distribution of the positive electrode active material in the positive electrode mixture layer is within a more suitable range, so that the charging capacity of the battery is better.
  • Kf/Kc can be any value of 6, 7, 8, 8.5, 9, 9.3, 9.5, 9.7, 10, 10.3, 10.5, 10.7, 11, 11.3, 11.5, 11.7, 12, 12.5, 13, 13.5, 13.7, 14, 14.5, 14.7, 15, 15.5, 16, 17, 19, 20, or a range consisting of any two values thereof.
  • Kf/Kc further indicates the preferred orientation of the positive electrode active material in the positive electrode mixture layer.
  • the lithium insertion ability of the negative electrode material is the determining factor that limits the charging capacity of the material. Properly reducing the kinetics of the positive electrode active material is conducive to improving the overall charging capacity of the battery and reducing the safety risks caused by battery lithium precipitation.
  • Kf/Kc Increasing the Kf/Kc of the positive electrode active material particles, more lithium ions migrate in the direction of the positive electrode active material particles parallel to the direction of the internal electric field of the battery, which will increase the difficulty of lithium ions escaping from the positive electrode and facilitate the embedding of negative electrode lithium ions.
  • too high Kf/Kc will cause the polarization of the lithium-ion battery to increase during the fast charging process, increase the temperature rise caused by charging, and cause the structure of the positive electrode active material to be destroyed due to the intensified reaction with the electrolyte. Therefore, Kf/Kc should be in the range of 6 to 20.
  • the parallel ratio of the (003) crystal plane in the positive electrode active material particles to the substrate plane is within a suitable range, which can ensure that the battery has a better charging capacity and the polarization of the battery is within a suitable range, so that the battery has better comprehensive performance.
  • the proportion of the number of particles of the positive electrode active material in the positive electrode mixture layer having a size of 1 micron to 3 microns to the total number of particles is greater than 60%, for example, it can be any value among 61%, 63%, 65%, 67%, 70%, 73%, 75%, 78%, 80%, 83%, 85%, 87%, 90% or a range consisting of any two of the values.
  • the uniformity of the particle size of the positive electrode active material in the positive electrode mixture layer has a significant effect on the charging performance of the battery.
  • Step 1 Place the positive electrode active material precursor Ni 0.52 Co 0.045 Mn 0.435 (OH) 2 and lithium carbonate in a mixing device and mix them thoroughly.
  • the molar ratio of lithium to the precursor of the lithium carbonate is 1.04:1.
  • Step 2 Place the mixed material in an atmosphere furnace for sintering.
  • the sintering time in the heating zone is 6 hours.
  • the sintering temperature in the constant temperature zone is 990°C, and the sintering time in the constant temperature zone is 12 hours.
  • the atmosphere in the constant temperature zone is an oxygen atmosphere, and the oxygen concentration in the constant temperature zone of the atmosphere furnace is 30%.
  • Step 3 The positive electrode active material obtained after sintering is crushed by rollers and then air flow crushed.
  • Step 4 Place the crushed positive electrode active material in a high-speed mixer for mixing at a mixing frequency of 40 Hz and a mixing time of 20 min.
  • Step 5 Place the mixed positive electrode active material in a kiln for secondary sintering to obtain a finished positive electrode active material.
  • the sintering temperature is 550° C. and the sintering time is 6 hours.
  • the half-peak width FWHW(003) of the (003) peak of the synthesized positive electrode active material is 0.088°, and the half-peak width FWHW(104) of the (104) peak is 0.097°.
  • Step 1 The positive electrode active material, binder polyvinylidene fluoride, conductive agent acetylene black, and conductive agent carbon nanotubes are fully mixed in a mass ratio of 97:1.5:1:0.5, and N-methylpyrrolidone (NMP) is added and stirred evenly in a stirrer to obtain a positive electrode slurry in which the positive electrode active material, binder, and conductive agent are evenly dispersed; the positive electrode slurry is evenly coated on an aluminum foil with a thickness of 12 microns, and the coating is applied to one side and then to the other side.
  • the coating surface density of a single side minus the weight of the aluminum foil is 16 mg/ cm2 .
  • Step 2 Dry the coated electrode in an oven at 100°C to 130°C.
  • Step 3 Roll the dried electrode sheet, and use X-ray diffraction test on the positive electrode mixture layer by controlling the rolling pressure, speed, roller temperature, and number of rolling times.
  • the peak area of the positive electrode mixture layer (003) peak is If(003)
  • the negative electrode active material, the thickener sodium carboxymethyl cellulose, the binder styrene butadiene rubber, and the conductive agent acetylene black are mixed in a mass ratio of 96:0.8:1.2:2, and deionized water is added to obtain a negative electrode slurry in which the negative electrode active material, the thickener sodium carboxymethyl cellulose, the binder styrene butadiene rubber, and the conductive agent acetylene black are evenly dispersed under the action of a stirrer; the negative electrode slurry is evenly coated on a copper foil of a certain thickness, and the surface density of one side minus the aluminum foil is 7.37 mg/ cm2 ; the coated electrode piece is transferred to an oven at 100-120°C for drying, and the other side of the electrode piece is coated with the same surface density, and then cold pressed and cut to obtain a negative electrode piece.
  • the organic solvent is a mixed solution containing ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) in a mass ratio of 1:1:1.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • the lithium salt LiPF 6 is dissolved in the organic solvent and mixed evenly to obtain an electrolyte.
  • the concentration of the lithium salt is 1.0 mol/L.
  • a polyethylene isolation film with a thickness of 12 ⁇ m was selected.
  • the positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is placed between the positive and negative electrode sheets to play an isolating role. After winding into a square bare battery cell, it is put into the outer package, and then baked to remove water, injected with the corresponding non-aqueous electrolyte, and sealed. After standing, hot and cold pressing, formation, capacity division and other processes, the finished battery is obtained.
  • step 1 of the preparation method of the positive electrode active material the precursor is Ni 0.78 Co 0.03 Mn 0.19 (OH) 2
  • the lithium salt is lithium hydroxide
  • the sintering temperature is 910° C. in step 2.
  • step 1 of the preparation method of the positive electrode active material is Ni 0.55 Co 0.12 Mn 0.33 (OH) 2 and the sintering temperature in the constant temperature zone in step 2 is 945°C.
  • step 1 of the preparation method of the positive electrode active material is Ni 0.60 Co 0.10 Mn 0.30 (OH) 2
  • the other steps are the same as those in Example 3.
  • step 1 of the preparation method of the positive electrode active material a zirconium oxide additive accounting for 0.4% of the total molar amount of metal elements other than lithium in the positive electrode active material is added, the other steps are the same as those of Example 4.
  • step 1 of the preparation method of the positive electrode active material a zirconium oxide additive accounting for 2.9% of the total molar amount of metal elements other than lithium in the positive electrode active material is added, the other steps are the same as those of Example 4.
  • step 1 of the preparation method of the positive electrode active material is to add a zirconium oxide additive accounting for 0.4% of the total molar amount of metal elements other than lithium in the positive electrode active material
  • step 4 is to thoroughly mix the crushed positive electrode active material with an aluminum oxide additive accounting for 0.5% of the total molar amount of metal elements other than lithium in the positive electrode active material
  • the other steps are the same as those in Example 4.
  • step 1 The steps of the preparation method of the positive electrode active material are the same as those of Example 4, except that in step 1, 0.4% of zirconium oxide and 0.1% of strontium oxide additives are added to the total molar amount of metal elements other than lithium in the positive electrode active material, and in step 4, the crushed positive electrode active material is thoroughly mixed with 0.5% of aluminum oxide additives to the total molar amount of metal elements other than lithium in the positive electrode active material.
  • step 1 of the preparation method of the positive electrode active material 0.4% of zirconium oxide and 0.1% of strontium oxide additives are added based on the total molar amount of metal elements other than lithium in the positive electrode active material, and in step 4, the crushed positive electrode active material is fully mixed with 0.5% of aluminum oxide and 0.2% of tungsten oxide additives based on the total molar amount of metal elements other than lithium in the positive electrode active material, the other steps are the same as those in Example 4.
  • step 1 the precursor is Ni 0.58 Co 0.14 Mn 0.28 (OH) 2 and 0.3% of a zirconium oxide additive is added to the total molar amount of the metal elements other than lithium in the positive electrode active material, and in step 4, the crushed positive electrode active material is thoroughly mixed with 0.4% of alumina and 0.2% of titanium oxide additives to the total molar amount of the metal elements other than lithium in the positive electrode active material.
  • step 1 the precursor is Ni 0.635 Co 0.09 Mn 0.275 (OH) 2
  • the lithium salt is lithium hydroxide
  • 0.1% of strontium oxide and 0.1% of barium oxide additives are added based on the total molar amount of metal elements other than lithium in the positive electrode active material
  • step 4 the crushed positive electrode active material is fully mixed with 0.9% of aluminum oxide and 0.1% of tungsten oxide additives based on the total molar amount of metal elements other than lithium in the positive electrode active material.
  • step 1 the precursor is Ni 0.68 Co 0.09 Mn 0.27 (OH) 2
  • the lithium salt is lithium hydroxide
  • 0.1% of strontium oxide and 0.1% of barium oxide additives are added based on the total molar amount of metal elements other than lithium in the positive electrode active material
  • the sintering temperature in the constant temperature zone is 935° C. in step 4
  • the crushed positive electrode active material is fully mixed with 1.1% of aluminum oxide and 0.2% of tungsten oxide additives based on the total molar amount of metal elements other than lithium in the positive electrode active material.
  • step 1 the precursor is Ni 0.72 Co 0.05 Mn 0.23 (OH) 2
  • the lithium salt is lithium hydroxide
  • 0.1% of strontium oxide and 0.1% of barium oxide additives are added based on the total molar amount of metal elements other than lithium in the positive electrode active material
  • the sintering temperature in the constant temperature zone is 910° C. in step 4
  • the crushed positive electrode active material is fully mixed with 0.7% of aluminum oxide and 0.2% of tungsten oxide additives based on the total molar amount of metal elements other than lithium in the positive electrode active material.
  • step 1 The steps of the preparation method of the positive electrode active material are the same as those of Example 4, except that in step 1, 0.15% of zirconium oxide and 0.75% of strontium oxide additives are added to the total molar amount of metal elements other than lithium in the positive electrode active material, and in step 4, the crushed positive electrode active material is thoroughly mixed with 0.1% of aluminum oxide additives to the total molar amount of metal elements other than lithium in the positive electrode active material.
  • step 2 of the preparation method of the positive electrode active material is 980° C. and the sintering time in the constant temperature zone is 24 hours, and the crushing parameters in step 3 are adjusted, the other steps are the same as those of Example 9.
  • step 3 of the preparation method of the positive electrode plate Except for the adjustment of the rolling parameters in step 3 of the preparation method of the positive electrode plate, the other steps are the same as those in Example 15.
  • step 1 of the preparation method of the positive electrode active material is Ni 0.46 Co 0.04 Mn 0.50 (OH) 2
  • the other steps are the same as those in Example 1.
  • step 1 of the preparation method of the positive electrode active material is Ni 0.60 Co 0.03 Mn 0.37 (OH) 2
  • the other steps are the same as those in Example 1.
  • step 1 of the method for preparing the positive electrode active material the precursor is Ni 0.82 Co 0.03 Mn 0.15 (OH) 2 and the lithium salt is lithium hydroxide, the other steps are the same as those in Example 1.
  • the test method for the half-peak width of the (003) diffraction peak of the positive electrode active material powder is FWHW(003) and the half-peak width of the (104) diffraction peak of the positive electrode active material powder is FWHW(104) is as follows:
  • the half-peak width of the (003) diffraction peak of the positive electrode active material powder is FWHW(003) and the half-peak width of the (104) diffraction peak of the positive electrode active material powder is FWHW(104). It can be obtained by using an X-ray powder diffractometer (X'pert PRO), according to the general rules for X-ray diffraction analysis JIS K 0131-1996, to obtain an X-ray diffraction spectrum, and deducting the background and K ⁇ 2 of the X-ray diffraction spectrum. Among them, FWHW(003) is the peak width at half the height of the (003) characteristic diffraction peak, and FWHW(104) is the peak width at half the height of the (104) characteristic diffraction peak, and the unit is °.
  • the test method for the ratio Kc of the peak area of the diffraction peak of the positive electrode active material (003) is Ic(003) and the peak area of the diffraction peak of the positive electrode active material (104) is Ic(104) is as follows:
  • the test method for the Kc value of the powder of the positive electrode active material is: a certain mass of the positive electrode active material powder is placed in an X-ray powder diffractometer, and the peak area of the (003) crystal plane diffraction peak and the peak area of the (104) crystal plane diffraction peak are obtained by X-ray diffraction analysis, thereby obtaining the Kc value of the powder of the positive electrode active material.
  • the test method for the ratio Kc of the peak area of the diffraction peak of the positive electrode mixture layer (003) is Ic(003) and the peak area of the diffraction peak of the positive electrode mixture layer (104) is Ic(104) is as follows:
  • the test method for the Kf value of the positive electrode mixture layer is: directly placing the positive electrode plate in the X-ray powder diffractometer, obtaining the peak area of the (003) crystal plane diffraction peak and the peak area of the (104) crystal plane diffraction peak by X-ray diffraction analysis, and then obtaining the powder Kf value of the positive electrode mixture layer.
  • the lithium ion batteries prepared in the examples and comparative examples were charged to 4.35V at a rate of 1/3C and discharged to 2.80V at a rate of 1/3C, and the discharge capacity was recorded.
  • the gram capacity of the positive electrode active material can be obtained by dividing the discharge capacity by the mass of the active material in the positive electrode sheet. The higher the gram capacity of the positive electrode active material, the higher the energy density that the battery can provide and the better the performance of the battery.
  • the lithium-ion batteries prepared in the examples and comparative examples were cycled for 1000 weeks at a charge-discharge rate of 1C to 4.35V and 1C to 2.80V, and the charge and discharge capacity of each cycle was recorded.
  • the discharge capacity of the 1000th cycle was divided by the discharge capacity of the first week, and the ratio obtained was the capacity retention rate of the battery after 1000 cycles. The higher the cycle capacity retention rate of the battery, the stronger the ability of the battery to resist capacity decay and the better the performance of the battery.
  • the lithium-ion battery prepared in the embodiment and the comparative example was charged to 4.35V at a rate of 1C and discharged to 2.80 at a rate of 1C for 1000 cycles, and then discharged to 2.80V at a rate of 1C.
  • the negative electrode plate in the battery was taken out, soaked in DMC for 12 hours to remove the impurities remaining on the surface of the negative electrode plate, and then baked in an oven at 80°C for 2 hours to remove DMC and residual electrolyte. Then, the content of Mn element and the content of Ni element in the negative electrode plate were tested by EPA6010D inductively coupled plasma atomic emission spectrometry.
  • the sum of these two contents was the total amount of Mn ions and Ni ions dissolved in the negative electrode plate after the battery cycled for 1000 weeks.
  • the lithium ion battery prepared in the embodiment and the comparative example was discharged to 2.8V at a rate of 1C, charged to 4.35V at a rate of 1C, and then discharged to 2.8V at a rate of 1C, and the discharge capacity C 1 was recorded.
  • the prepared lithium ion battery was then charged to 4.35V at a current of 1C 1 , and then discharged at a current of 1C 1 for 30 minutes and then left to stand for 180 minutes, and the voltage V 1 of the battery after standing was recorded. Then, the battery was discharged at a current of 5C 1 for 10 seconds, and the voltage V 2 at the end of the 10-second discharge was recorded.
  • the initial impedance R1 (V 2 -V 1 )/5C 1 .
  • the prepared lithium ion battery was cycled for 1000 cycles according to the charge and discharge regime of charging to 4.35V at a rate of 1C and discharging to 2.80 at a rate of 1C. Then the battery with 1000 cycles was discharged to 2.8V at 1C 1 rate, charged to 4.35V at 1C 1 rate, and then discharged to 2.8V at 1C 1 rate, and the discharge capacity C 2 was recorded. Then the prepared lithium-ion battery was charged to 4.35V at 1C 2 current, and then discharged at 1C 2 current for 30 minutes and then left to stand for 180 minutes, and the voltage V 3 of the battery after standing was recorded.
  • the capacity retention rate of the battery prepared in Example 1 after 1000 cycles is 83.1%, which is higher than 61.2% of Comparative Example 1 and 66.1% of Comparative Example 2, indicating that the battery prepared in Example 1 has better cycle stability;
  • the impedance increase of the battery prepared in Example 1 after 1000 cycles is 35.2%, which is lower than 92.6% of Comparative Example 1 and 86.5% of Comparative Example 2, indicating that the battery prepared in Example 1 has better resistance to power attenuation.
  • the excellent performance of Example 1 is due to the design of the molar content of cobalt and manganese, resulting in a lower total amount of Mn ions and Ni ions dissolved in its positive electrode active material. After 1000 cycles of the battery prepared in Example 1, the total amount of Mn ions and Ni ions dissolved in the negative electrode sheet is 342.1ppm, which is much lower than 667.3ppm of Comparative Example 1 and 607.9ppm of Comparative Example 2.
  • Example 3 Compared with Example 3, the capacity retention rate of the battery prepared in Example 2 after 1000 cycles is 77.5%, which is higher than 34.2% of Comparative Example 3, indicating that the battery prepared in Example 2 has better cycle stability; the impedance increase of the battery prepared in Example 2 after 1000 cycles is 42.3%, which is lower than 126.8% of Comparative Example 3, indicating that the battery prepared in Example 2 has better resistance to power attenuation.
  • the excellent performance of Example 2 is due to the design of the molar content of cobalt and manganese, resulting in a lower total amount of Mn ions and Ni ions dissolved in its positive electrode active material. After 1000 cycles of the battery prepared in Example 2, the total amount of Mn ions and Ni ions dissolved in the negative electrode sheet is 421.7ppm, which is much lower than 826.3ppm of Comparative Example 3.
  • Example 3 Comparing Example 1 with Example 3, the capacity retention rate of the battery prepared in Example 3 after 1000 cycles is 84.3%, which is higher than 83.1% of Example 3, indicating that the battery prepared in Example 3 has better cycle stability; the impedance increase of the battery prepared in Example 3 after 1000 cycles is 28.7%, which is lower than 35.2% of Example 1, indicating that the battery prepared in Example 3 has better resistance to power attenuation.
  • the excellent performance of Example 3 is due to its better molar content ratio design of cobalt and manganese, resulting in a lower total amount of Mn ions and Ni ions dissolved in its positive electrode active material. After 1000 cycles of the battery prepared in Example 3, the total amount of Mn ions and Ni ions dissolved in the negative electrode sheet is 285.5ppm, which is lower than 342.1ppm in Example 3.
  • Example 5 Compared with Example 4, the capacity retention rate of the battery prepared in Example 5 after 1000 cycles is 88.6%, which is higher than 86.5% of Example 4, indicating that the battery prepared in Example 5 has better cycle stability; the impedance increase of the battery prepared in Example 5 after 1000 cycles is 25.1%, which is lower than 31.3% of Example 4, indicating that the battery prepared in Example 3 has better resistance to power attenuation.
  • the excellent performance of Example 5 is due to the introduction of an appropriate amount of the added element Zr, which improves the structural stability of the material, resulting in a lower total amount of Mn ions and Ni ions dissolved in its positive electrode active material. After 1000 cycles of the battery prepared in Example 5, the total amount of Mn ions and Ni ions dissolved in the negative electrode sheet is 241.3ppm, which is lower than 292.0ppm of Example 4.
  • Example 6 Comparing Example 6 with Example 5, the positive electrode gram capacity of the battery prepared in Example 6 is 178.6 mAh/g, which is much lower than 186.5 mAh/g of Example 5, indicating that excessive addition of Zr element will affect the energy density of the battery.
  • Example 7 Compared with Example 5, the capacity retention rate of the battery prepared in Example 7 after 1000 cycles is 93.7%, which is higher than 88.6% of Example 5, indicating that the battery prepared in Example 7 has better cycle stability; the impedance increase of the battery prepared in Example 7 after 1000 cycles is 16.7%, which is lower than 25.1% of Example 5, indicating that the battery prepared in Example 7 has better resistance to power attenuation.
  • the excellent performance of Example 7 is due to the introduction of appropriate amounts of added elements Zr and Al to improve the structural stability of the material, resulting in a lower total amount of Mn ions and Ni ions dissolved in its positive electrode active material. After 1000 cycles of the battery prepared in Example 7, the total amount of Mn ions and Ni ions dissolved in the negative electrode sheet is 191.4ppm, which is lower than 241.3ppm in Example 5.
  • Example 7 Compared with Example 7, the capacity retention rates of the batteries prepared in Example 8, Example 9 and Example 10 after 1000 cycles were 94.9%, 96.2% and 95.8%, respectively, which were higher than 93.7% of Example 7, indicating that the batteries prepared in Example 8, Example 9 and Example 10 had better cycle stability; the impedance increase of the batteries prepared in Example 8, Example 9 and Example 10 after 1000 cycles was 12.6%, 6.8% and 10.7%, respectively, which was lower than 16.7% of Example 7, indicating that the batteries prepared in Example 8, Example 9 and Example 10 had better resistance to power attenuation.
  • Example 8 The excellent performance of Example 8, Example 9 and Example 10 is due to the optional addition of Ti, Sr and W elements on the basis of the co-introduction of appropriate amounts of added elements Zr and Al, which further improves the structural stability of the material and makes the positive active material have a lower total amount of Mn ions and Ni ions dissolved.
  • the total amounts of Mn ions and Ni ions dissolved from the negative electrode sheets were 153.7 ppm, 126.1 ppm and 137.4 ppm, respectively, which were lower than 191.4 ppm in Example 7.
  • Example 11, Example 12 and Example 13 further show that by designing the molar ratio of cobalt and manganese, and the type and content of additive elements, the battery prepared by the synthesized positive electrode active material has high positive electrode material gram capacity, high capacity retention rate and better resistance to power attenuation.
  • the positive electrode gram capacity of Example 11, Example 12 and Example 13 is 190.7mAh/g, 196.4mAh/g and 196.1mAh/g, respectively, and the capacity retention rate after 1000 cycles is 92.5%, 92.1% and 91.5%, respectively, and the impedance increase after 1000 cycles is 14.5%, 13.8% and 16.7%, respectively.
  • Example 8 Compared with Example 8, the capacity retention rate of the battery prepared in Example 8 after 1000 cycles is 94.9%, which is higher than 87.3% of Example 14, indicating that the battery prepared in Example 8 has better cycle stability; the impedance increase of the battery prepared in Example 8 after 1000 cycles is 12.6%, which is lower than 25.1% of Example 1, indicating that the battery prepared in Example 8 has better resistance to power attenuation.
  • the excellent performance of Example 8 is due to the fact that the introduction of the added elements Zr and Al in a suitable range can improve the structural stability of the material, resulting in a lower total amount of Mn ions and Ni ions dissolved in the positive electrode active material. After 1000 cycles of the battery prepared in Example 8, the total amount of Mn ions and Ni ions dissolved in the negative electrode sheet is 153.7ppm, which is lower than 224.3ppm in Example 5.
  • Example 9 Compared with Example 9, the capacity retention rate of the battery prepared in Example 9 after 1000 cycles is 96.2%, which is higher than 86.3% of Example 15, indicating that the battery prepared in Example 9 has better cycle stability; the impedance increase of the battery prepared in Example 9 after 1000 cycles is 6.8%, which is lower than 35.5% of Example 15, indicating that the battery prepared in Example 9 has better resistance to power attenuation.
  • the excellent performance of Example 9 is due to its suitable FWHW (003) and FWHW (104) design, which can improve the structural stability of the material, resulting in a lower total amount of Mn ions and Ni ions dissolved in its positive electrode active material.
  • the total amount of Mn ions and Ni ions dissolved in the negative electrode sheet is 126.1ppm, which is lower than 273.5ppm of Comparative Example 15.
  • FWHW(003) and FWHW(104) are too low, it indicates that the growth of the positive electrode active material particles is too sufficient, resulting in a decrease in kinetics, which affects the gram capacity of the positive electrode active material.
  • the gram capacity of the positive electrode material of the battery prepared in Example 9 is 188.6 mAh/g, which is much higher than 174.2 mAh/g of Example 15.
  • Example 9 Compared with Example 9, the capacity retention rate of the battery prepared in Example 9 after 1000 cycles is 96.2%, which is higher than 87.9% of Example 16, indicating that the battery prepared in Example 9 has better cycle stability; the impedance increase of the battery prepared in Example 9 after 1000 cycles is 6.8%, which is lower than 29.6% of Example 16, indicating that the battery prepared in Example 9 has better resistance to power attenuation.
  • the excellent performance of Example 9 is due to its suitable FWHW (003) and FWHW (104) design, which can improve the structural stability of the material, resulting in a lower total amount of Mn ions and Ni ions dissolved in its positive electrode active material. After 1000 cycles of the battery prepared in Example 9, the total amount of Mn ions and Ni ions dissolved in the negative electrode sheet is 126.1ppm, which is lower than 237.9ppm of Example 16.
  • Example 9 Compared with Example 9, the capacity retention rate of the battery prepared in Example 9 after 1000 cycles is 96.2%, which is higher than 77.6% in Example 17 and 81.5% in Example 18, indicating that the battery prepared in Example 9 has better cycle stability; the impedance increase of the battery prepared in Example 9 after 1000 cycles is 6.8%, which is lower than 38.8% in Example 17 and 32.3% in Example 18, indicating that the battery prepared in Example 9 has better resistance to power attenuation.
  • the excellent performance of Example 9 is due to its suitable positive electrode active material Kc value and positive electrode mixture layer Kf value design, resulting in a lower total amount of Mn ions and Ni ions dissolved in its positive electrode active material. After 1000 cycles of the battery prepared in Example 9, the total amount of Mn ions and Ni ions dissolved in the negative electrode sheet is 126.1ppm, which is lower than 358.1ppm in Example 17 and 235.8ppm in Example 18.
  • the dissolution of transition metal elements nickel, manganese and cobalt in the positive electrode active materials can reduce the dissolution of transition metal elements nickel, manganese and cobalt in the positive electrode active materials, and improve the battery's charging capacity, cycle life and safety performance.
  • the Ni content in the material is high, the depth of lithium extraction and insertion of the positive electrode active materials increases, and the structural stability of the material is poor.
  • the Mn content increases, the surface protective film of the negative electrode is easily destroyed after Mn dissolves, resulting in an increase in impedance, increasing the risk of lithium precipitation, and reducing the battery's charging capacity, cycle life and safety performance.
  • the amount and composition of added elements the dissolution of metal ions in the positive electrode active materials during use can be suppressed, and the battery's charging capacity, cycle life and safety performance can be improved.
  • the ratio of positive electrode sheet compaction and positive electrode powder compaction When the ratio of positive electrode sheet compaction and positive electrode powder compaction is low, the electrical contact area between positive electrode particles and between positive electrode particles and conductive agents is insufficient, resulting in a large ohmic internal resistance of the positive electrode mixture layer, affecting the charging performance of the battery; when the ratio of electrode sheet compaction and positive electrode powder compaction is high, the compaction of the positive electrode mixture layer is high, which easily leads to the formation of sliding cracks in the positive electrode active material particles, resulting in the deterioration of the electrolyte and the dissolution of transition metals, affecting the charging capacity, cycle life and safety performance.

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Abstract

本发明公开了一种正极活性材料及锂离子电池。所述正极活性材料包括锂镍钴锰氧化物；锂镍钴锰氧化物中，以镍、钴和锰元素的摩尔总量为100％计，锰元素的摩尔量记为m％，钴元素的摩尔量记为n％，满足下述条件：20<n+m<50，且0.1<n/m<0.6，正极活性材料的(003)峰的半峰宽记为FWHW(003)，(104)峰的半峰宽记为FWHW(104)；FWHW(003)和FWHW(104)满足如下条件：0.4≤FWHW(003)/FWHW(104)≤2.0。本发明通过合理的设计添加元素的量和成分，可抑制正极活性材料在使用过程中的金属离子溶解，改善电池的充电能力、循环寿命和安全性能。本发明可降低正极颗粒在正极极片加工过程产生的微裂纹，同时保证电池拥有较好的充电能力、循环寿命和安全性能。

Description

一种正极活性材料及锂离子电池
相关申请交叉引用
本申请要求由申请人欣旺达电动汽车电池有限公司于2022年12月1 日提交的、题目为一种正极活性材料及锂离子电池的中国专利申请申请号 为202211523409.2的优先权，该申请的全部内容通过引用并入本文。
技术领域
本申请涉及一种正极活性材料及锂离子电池，属于二次电池技术领域。
背景技术
近年来随着传统燃油车造成的环境问题日益突显，人们亟需一种绿色、低碳、可持续的汽车可替代能源。二次电池，例如锂离子电池作为一种清洁能源，因其高的能量密度和长寿命，近年来被广泛使用。相比于传统燃油汽车，以锂离子电池为动力能源的新能源汽车因其需要通过对锂离子电池进行充电的方式进行能量的补充，其充电时间直接影响了新能源汽车用户的体验。因此，提高二次电池的充电速率一直是新能源行业的重要研究方向。
发明内容
本申请的目的是提供一种正极活性材料，采用该正极活性材料制备的锂离子电池，可以降低锂离子电池中正极活性材料的过渡金属的溶出，减少滑移裂纹鲜界面与电解液的交互作用，提升二次电池的充电能力、循环寿命以及安全性能。
本申请提供的正极活性材料，包括锂镍钴锰氧化物；
所述锂镍钴锰氧化物中，以镍元素、钴元素和锰元素的摩尔总量为100％计，所述锰元素的摩尔量记为m％，所述钴元素的摩尔量记为n％，满足下述条件：20<n+m<50，且0.1<n/m<0.6；所述正极活性材料的(003)峰的半峰宽记为FWHW(003)，所述正极活性材料的(104)峰的半峰宽记为FWHW(104)；所述FWHW(003)和所述FWHW (104)满足如下条件：0.4≤FWHW(003)/FWHW(104)≤2.0。
进一步地，所述锰元素和所述钴元素的摩尔含量满足下述条件中任一种：
(ⅰ)19≤m<43.5；
(ⅱ)3.0≤n≤12；
(ⅲ)0.10≤n/m≤0.502。
进一步地，所述正极活性材料还包括M元素，所述M元素包含Zr，以及Al、Mg、Ti、Y、Sr、Y、Mo、Nb、Sn、Ba、La、Ce元素中的至少一种；
以所述镍元素、所述钴元素和所述锰元素的总量为100％计，所述M元素的摩尔量与所述镍元素、所述钴元素和所述锰元素的摩尔总量的百分比记为x％，0.1≤x≤2.5。
更进一步地，所述M元素包含Zr元素、Al元素，以及Mg、Ti、Y、Sr、Y、Mo、Nb、Sn、Ba、La、Ce、W元素中的至少一种，所述M元素的摩尔含量记为x％，Zr的摩尔含量记为x1％，Al的摩尔含量记为x2％，x、x1和x2满足下述条件中任一种：
(ⅳ)0.20≤x1≤0.45；
(ⅴ)0.15≤x2≤1.5；
(ⅵ)0.2≤x1/x2≤1；
(ⅶ)0<(x-x1-x2)/x<0.5。
本申请正极活性材料的(003)峰的半峰宽记为FWHW(003)，所述正极活性材料的(104)峰的半峰宽记为FWHW(104)；
所述FWHW(003)的范围为0.06～0.15°；
所述FWHW(104)的范围为0.06～0.15°。
本申请正极活性材料的(003)峰的峰面积记为Ic(003)，(104)峰的峰面积记为Ic(104)，Kc为Ic(003)/Ic(104)，1≤Kc≤2。
本申请正极活性材料包含Li aNi bCo m/100Mn n/100M x/100O 2，0.80≤a≤1.10，0.4<b<0.8，20<n+m<50，且0.1<n/m<0.6，0.1≤x≤2.5，M包括Zr，以及Al、Mg、Ti、Y、Sr、Y、Mo、Nb、Sn、Ba、La、Ce和W中的至少一种。
在所述正极活性材料的基础上，本申请还提供了一种二次电池，包括正极；所述正极包括正极集流体和设置于所述正极集流体上的正极合剂层，所述正极合剂层由所述正极活性材料制成；
所述正极合剂层的(003)峰的峰面积记为If(003)，(104)峰的峰面积记为If(104)，Kf为If(003)/If(104)，10≤Kf≤20，6≤Kf/Kc≤20。
所述正极合剂层中所述正极活性材料形成的颗粒尺寸在1微米～3微米的个数占总的颗粒个数的比例大于60％；
所述正极合剂层中正极活性材料颗粒尺寸的均匀性对电池的充电性能有显著的影响，正极活剂层中正极活性材料颗粒尺寸的越均匀，正极活性材料活性颗粒在大电流的充电条件下不同颗粒之间的电流密度差异越小，即表明不同颗粒之间脱锂深度一致，极化降低，进而电池的温升降低，保证电池有较好的充电能力以及使用寿命。
具体实施方式
下述实施例中所使用的实验方法如无特殊说明，均为常规方法。
下述实施例中所用的材料、试剂等，如无特殊说明，均可从商业途径得到。
本申请提供的正极活性材料，包括锂镍钴锰氧化物；
所述锂镍钴锰氧化物中，以镍元素、钴元素和锰元素的总摩尔量为100％计，所述锰元素的摩尔量记为m％，所述钴元素的摩尔量记为n％，满足下述条件：20<n+m<50，且0.1<n/m<0.6；所述正极活性材料的(003)峰的半峰宽记为FWHW(003)，所述正极活性材料的(104)峰的半峰宽记为FWHW(104)；所述FWHW(003)和所述FWHW(104)满足如下条件：0.4≤FWHW(003)/FWHW(104)≤2.0。例如FWHW(003)/FWHW(104)的值可以为0.4、0.5、0.6、0.7、0.8、0.9、0.99、1.0、1.1、1.3、1.5、1.8、2.0中的任意值或其中的任意两个值组成的范围。
根据本申请的一些实施例，22<n+m<48，0.103<n/m<0.502。
根据本申请的一些实施例，所述正极活性材料的(003)峰的半峰宽记为FWHW(003)，所述正极活性材料的(104)峰的半峰宽记为FWHW(104)，0.4≤FWHW(003)/FWHW(104)≤1.5。当正极活性材 料的FWHW(003)/FWHW(104)在上述范围，正极活性材料晶体结构的稳定性较高，二次电池的充电能力、循环寿命及安全性能的到提升。根据本申请的一些实施例，0.5≤FWHW(003)/FWHW(104)<1。当FWHW(003)/FWHW(104)在上述范围时，表明正极活性材料颗粒晶格内部残余应力低或锂离子与过渡金属离子的混排率低，而晶格内部的残余应力或离子混排会导致晶格中的原子偏离平衡位置，导致FWHW(003)或FWHW(104)中某一值的偏高，导致FWHW(003)/FWHW(104)比值发生变化。而晶格内部的残余应力或离子混排会导致锂离子在正极活性材料中脱出的势垒增加，降低电池的充电能力。
在所述正极活性材料中，锰元素和钴元素可以稳定锂镍钴锰氧化物在脱锂过程结构的稳定性，对材料结构具有支撑作用。锰元素和钴元素过高时，则参与电化学反应的镍元素比例降低，进而导致锂镍钴锰氧化物的能量密度降低。镍元素和锰元素在充电过程中容易向晶格中的四面体空位迁移，导致正极活性材料的晶格发生畸变，破坏材料晶格的稳定性，同时四面体空位的镍离子和锰离子也会在电场的作用下向电解液中迁移并溶解，溶解的镍离子和锰离子(尤其是锰离子)易于在负极还原，破坏负极的表面保护膜，导致阻抗的增加，提升析锂风险，降低电池的充电能力、循环寿命和安全性能。所述正极活性材料中钴元素的存在可以抑制镍离子和锰离子在充电过程中向晶格中的四面体空位迁移，但钴含量较高时会导致正极活性材料的容量降低，同时钴元素是地壳稀缺金属，钴元素含量过高也会提高正极活性材料的成本。通过控制镍、钴、锰元素的含量，以及形成的正极活性材料晶体的稳定性，可有效的改善上述问题。
根据本申请的一些实施例，19≤m<43.5。例如m可以为19、20、21、23、25、27、27.5、28、30、32、33、34、37、39、40、42、43.5中的任意值中的任意值或其中的任意两个值组成的范围。
根据本申请的一些实施例，20≤m≤33。
根据本申请的一些实施例，20≤m≤30。当m在上述范围时，能进一步优化正极活性材料晶体结构，使正极活性材料更加稳定。
根据本申请的一些实施例，3≤n≤12。例如n可以为3、4.5、5、7、8、9、10、11、12、14中的任意值或其中的任意两个值组成的范围。
根据本申请的一些实施例，4.5≤n≤9。
根据本申请的一些实施例，0.10≤n/m≤0.502。例如可以为0.10、0.15、0.18、0.20、0.22、0.25、0.28、0.30、0.32、0.35、0.38、0.40、0.42、0.45、0.48、0.502中的任意值或其中的任意两个值组成的范围值。当n/m在此范围内，能够进一步控制正极活性材料的晶体结构，使二次电池的性能更优。
根据本申请的一些实施例，0.15≤n/m≤0.35。
根据本申请的一些实施例，所述正极活性材料还包括M元素，所述M元素包含Zr、Al、Mg、Ti、Y、Sr、Y、Mo、Nb、Sn、Ba、La、Ce、W元素中的至少一种。合适的M元素可以与锂镍钴锰氧化物中氧形成化学键，可以提升锂镍钴锰氧化物中金属与氧八面体结构的稳定性。同时在快速充电的情况下，降低过渡金属在负极极片上的析出以及正极活性材料晶格氧的释放会导致安全风险。
根据本申请的一些实施例，所述M元素包含Zr元素，以及Al、Mg、Ti、Y、Sr、Y、Mo、Nb、Sn、Ba、La、Ce元素中的至少一种。Zr元素因与氧形成的化学键的键能远大于镍、钴和锰元素与氧形成的化学能，添加包括Zr在内的M元素后，可以进一步提升锂镍钴锰氧化物中金属与氧八面体结构的稳定性。
根据本申请的一些实施例，所述M元素包含W元素，以及Zr、Al、Mg、Ti、Y、Sr、Y、Mo、Nb、Sn、Ba、La、Ce元素中的至少一种。
根据本申请的一些实施例，所述M元素包含Zr元素和Al元素，以及Mg、Ti、Y、Sr、Y、Mo、Nb、Sn、Ba、La、Ce、W元素中的至少一种。Al元素与正极活性材料中的锂镍钴锰氧化物中氧形成化学键的键能小于Zr元素，但Al元素成键后有利于提高了锂镍钴锰氧化物中镍离子向晶格锂所在位置的迁移能，降低晶格锂所在位置的镍离子的占比，提高锂离子迁移速率，进一步降低了电池的充电能力。
根据本申请的一些实施例，所述M元素包含Zr元素和W元素，以及Al、Mg、Ti、Y、Sr、Y、Mo、Nb、Sn、Ba、La、Ce元素中的至少一种。
根据本申请的一些实施例，以所述镍元素、所述钴元素和所述锰元素 的总量摩尔为100％计，所述M元素的摩尔量与所述镍元素、所述钴元素和所述锰元素的摩尔总量的比值记为x％，0.1≤x≤2.5。例如x可以为0.1、0.3、0.5、0.7、0.9、1.0、1.1、1.3、1.5、1.7、1.9、2.0、2.2、2.4、2.5中的任意值或其中的任意两个值组成的范围。通过调整M元素的含量可有效的降低金属溶出和晶格氧释放，能进一步提升电池的充电能力、使用寿命和安全性能。
根据本申请的一些实施例，0.2≤x≤1.5。由于电池在快速充电的情况下，锂镍钴锰氧化物会发生过渡金属镍和锰的溶出，导致正极活性材料结构稳定性的降低，以及对负极极片表面保护膜的破坏，降低电池的充电能力和使用寿命。过渡金属在负极侧的析出以及晶格氧的释放会导致安全风险。当M元素含量在上述范围，能够在保证正极活性材料结构稳定性的同时，减少对正极活性材料可利用的容量的影响，可以使电池兼具高的容量、优异的充电能力、使用寿命和安全性能。
根据本申请的一些实施例，所述M元素包含Zr元素和Al元素，以及Mg、Ti、Y、Sr、Y、Mo、Nb、Sn、Ba、La、Ce、W元素中的至少一种；其中，所述M元素的摩尔含量记为x％，Zr的摩尔含量记为x1％，Al的摩尔含量记为x2％。
根据本申请的一些实施例，0.20≤x1≤0.45。例如x1可以为0.20、0.22、0.24、0.25、0.27、0.29、0.30、0.32、0.34、0.36、0.39、0.40、0.42、0.44、0.45中的任意值或其中的任意两个值组成的范围。通过所述Zr元素的添加可有效的降低金属溶出和晶格氧释放，提升电池的充电能力、使用寿命和安全性能。
根据本申请的一些实施例，0.24≤x1≤0.42。
根据本申请的一些实施例，0.15≤x2≤1.5。例如x2可以为0.15、0.20、0.25、0.3、0.32、0.35、0.37、0.40、0.45、0.47、0.50、0.53、0.57、0.59、0.60、0、63、0.65、0.68、0.70、0.73、0.75、0.78、0.80、0.85、0.90、0.93、0.95、1.0、1.2、1.5中的任意值或其中的任意两个值组成的范围。通过控制所述Al元素的添加可有效的降低金属溶出和晶格氧释放，提升电池的充电能力、使用寿命和安全性能。
根据本申请的一些实施例，0.25≤x2≤1.2。
根据本申请的一些实施例，0.3≤x2≤0.95。
根据本申请的一些实施例，0.2≤x1/x2≤1。例如x1/x2可以为0.20、0.25、0.3、0.32、0.35、0.37、0.40、0.45、0.47、0.50、0.53、0.57、0.59、0.60、0、63、0.65、0.68、0.70、0.73、0.75、0.78、0.80、0.85、0.90、0.93、0.95、1.0中的任意值或其中的任意两个值组成的范围值。当控制Al元素的含量大于或等于Zr元素的含量，且二者的比例在上述范围，可以使正极活性材料内部晶格锂的占比以及晶体结构的稳定性，使正极活性材料晶体结构处于更优状态，进一步提高电池的整体性能。
根据本申请的一些实施例，0<(x-x1-x2)/x<0.5。例如(x-x1-x2)/x可以为0.001、0.05、0.1、0.13、0.15、0.18、0.20、0.25、0.3、0.32、0.35、0.37、0.40、0.45、0.47、0.50中的任意值或其中的任意两个值组成的范围值。当除M元素中包含Al元素、Zr元素的同时，还包含其他元素，且含量在上述范围能进一步优化正极活性材料晶体结构，使电池具有更优的综合性能。
根据本申请的一些实施例，0.1≤(x-x1-x2)/x≤0.42。当满足上述范围，正极活性材料的综合性能更优。
根据本申请的一些实施例，所述正极活性材料的(003)峰的半峰宽记为FWHW(003)，所述FWHW(003)的范围为0.06～0.15°。例如FWHW(003)可以为0.06°、0.07°、0.09°、0.10°、0.12°、0.14°、0.15°中的任意值或其中的任意两个值组成的范围值。
根据本申请的一些实施例，所述正极活性材料的(104)峰的半峰宽记为FWHW(104)，所述FWHW(104)的范围为0.06～0.15°。例如FWHW(104)可以为0.06°、0.07°、0.09°、0.10°、0.12°、0.14°、0.15°中的任意值或其中的任意两个值组成的范围值。
所述正极活性材料的特征峰的半峰宽FWHW表示在扣除XRD曲线的背底以及Kα2后，特征峰高度一半处的峰宽度，单位为°。XRD的扫描速度是2°/min。(003)特征峰和(104)特征峰的半峰宽FWHM小于0.15°时，表明正极活性材料的晶型完整，结晶性好；若(003)特征峰和(104)特征峰的半峰宽FWHM大于0.15°时，表明正极活性材料中部分原子的位置偏离理想晶体的位置，表明材料的结晶性差，会导致材料的使 用寿命。但半峰宽FWHM小于0.06°时，表明正极活性材料不仅结晶性好，同时晶粒的尺寸较大。较大的晶粒尺寸使得在充电过程中锂离子在正极活性材料体相的迁移距离变长，导致电池的充电能力降低。因此正极活性材料(003)和(104)的特征峰半峰宽宜在一个适当的范围，可以保证电池具有较好的使用寿命和充电能力。
根据本申请的一些实施例，所述FWHW(003)的范围为0.07～0.098°。
根据本申请的一些实施例，所述FWHW(003)的范围为0.09～0.12°。
根据本申请的一些实施例，所述正极活性材料的(003)峰的峰面积记为Ic(003)，(104)峰的峰面积记为Ic(104)，Kc为Ic(003)/Ic(104)，1≤Kc≤2。例如Kc可以为1、1.1、1.2、1.3、1.35、1.4、1.45、1.48、1.5、1.52、1.54、1.56、1.58、1.6、1.63、1.65、1.67、1.7、1.73、1.75、1.78、1.8、1.85、1.9、2.0中的任意值或其中的任意两个值组成的范围。
Kc可以体现正极活性材料的结晶性，当正极活性材料Kc的值在1.0～2.0，表明正极活性材料的结晶性良好，材料内部的缺陷少。Kc低于1.0时，正极活性材料的结晶性较差，内部存在较多的缺陷，会影响正极活性材料的结构稳定性，使用时可能导致电池的容量低，锂离子脱出受阻，影响材料的快充能力和长期寿命。
根据本申请的一些实施例，1.3≤Kc≤1.7。
本申请正极活性材料可通过下述方法制备得到：
1)将前驱体Ni bCo m/100Mn n/100(OH) 2和锂盐、含添加金属元素M1的添加剂A1置于混料设备中进行充分混合，锂盐中的锂和三元材料前驱体Ni bCo m/100Mn n/100(OH) 2的比例为a：1.95≤a≤1.2，锂盐可为碳酸锂、氢氧化锂或其他可以提供锂元素的化合物。M1可选择Mg、Al、Ti、Y、Sr、Zr、Mo、Nb、Sn、Ba、La、Ce中的一种或者多种，M1至少包含Zr元素，添加剂A1为含添加元素M1的氧化物、氢氧化物或其他化合物。
2)把混合后的材料装入匣钵中，并置于气氛炉进行烧结，升温区的温度在25℃-950℃，恒温区的烧结温度在800～1000℃，升温区和恒温区总的烧结时间15～40小时，烧结过程中通入纯氧，保证窑炉内氧气的浓度为 20％～99％。通过对匣钵中正极活性材料的填充量、升温区升温制度、升温区和恒温区烧结温度、时间气氛的控制，可以控制正极活性材料的特征峰Ic(003)/Ic(104)的比值Kc，正极活性材料(003)和(104)特征峰的半峰宽，正极活性材料(003)和(104)特征峰的半峰宽的比值，也可以调控正极活性材料颗粒尺寸大小和均匀性。
3)把烧结后得到的正极活性材料进行对辊和气流破碎，通过控制气流破碎的参数，如进气喷嘴的直径、进料频率、引风频率、气压、料仓物料重量等参数，可以对调控正极活性材料颗粒的尺寸分布。
4)将破碎后正极活性材料与含添加元素M2的添加剂A2置于混料设备中进行充分混合，M2可选择Mg、Al、Ti、Y、Sr、Zr、Mo、Nb、Sn、Ba、La、Ce中的一种或者多种，添加剂A2为含添加元素M2的氧化物、氢氧化物或其他化合物。
5)将混合均匀的正极活性材料、添加剂混合物置于窑炉中进行二次烧结即得到成品正极活性材料。烧结温度为350～850℃，烧结时间为5～20小时。二次烧结可以修补破碎过程中破坏的正极颗粒表面，降低材料的残碱，同时在表面形成一层具有一定厚度的保护层。
在所述正极活性材料的基础上，本申请还提供了一种二次电池，包括正极；所述正极包括正极集流体和设置于所述正极集流体上的正极合剂层，所述正极合剂层由所述正极活性材料制成；
根据本申请的一些实施例，所述正极合剂层的(003)峰的峰面积记为If(003)，(104)峰的峰面积记为If(104)，Kf为If(003)/If(104)，10≤Kf≤20。例如Kf可以为10、11、12、13、13.3、13.5、13.7、14、14.5、14.7、15、15.3、15.5、15.7、16、16.3、16.5、16.7、17、17.5、18、19、20中的任意值或其中的任意两个值组成的范围值。
Kf的比值反映所述正极合剂层中正极活性材料的择优取向。比值≥20时，表明择优取向越严重，即说明在正极合剂层制备过程正极活性材料的晶面发生显著的滑移。这种滑移会导致正极颗粒表明的裂纹，导致材料的稳定性差，容易发生金属溶解以及与界面副反应。且Kf越大，锂离子脱出方向与电场方向的夹角越接近90℃，不利于锂离子的脱出，降低电池的充电能力。Kf比值≤10时，正极粉末与导电剂粘接效果差，导致电池的内 阻较高，在充电过程中锂离子电池的欧姆极化大，降低电池的充电能力。
根据本申请的一些实施例，13≤Kf≤17。当Kf在此范围内时，正极活性材料在正极合剂层中的取向分布在更加合适的范围内，使电池的充电能力更优。
根据本申请的一些实施例，6≤Kf/Kc≤20。例如Kf/Kc可以为6、7、8、8.5、9、9.3、9.5、9.7、10、10.3、10.5、10.7、11、11.3、11.5、11.7、12、12.5、13、13.5、13.7、14、14.5、14.7、15、15.5、16、17、19、20中的任意值或其中的任意两个值组成的范围。
Kf/Kc更进一步地表示正极合剂层中正极活性材料的择优取向，Kf/Kc越高，表示正极活性材料颗粒中(003)晶面与基材平面的平行比例增加。对于快充型电池，负极材料的嵌锂能力是限制材料充电能力的决定因素，适当的降低正极活性材料的动力学有利于提升电池整体的充电能力，降低电池析锂带来的安全风险。提高正极活性材料颗粒的Kf/Kc，更多锂离子在正极活性材料颗粒迁移的方向平行于电池内部电场的方向，会增加锂离子在正极脱出的难度，有利于负极锂离子的嵌入。但过高的Kf/Kc，会导致在快速充电过程中锂离子电池极化变大，充电引起的温升增加，导致因与电解液的反应加剧而破坏正极活性材料的结构。因此，Kf/Kc宜在6～20的范围内。
根据本申请的一些实施例，8≤Kf/Kc≤14。当Kf/Kc在此范围内正极活性材料颗粒中(003)晶面与基材平面的平行比例在合适的范围内，能够保证电池在具有较优的充电能力的同时，电池的极化在合适的范围，使电池具有更优的综合性能。
所述正极合剂层中所述正极活性材料形成的颗粒尺寸在1微米～3微米的个数占总的颗粒个数的比例大于60％。例如可以为61％、63％、65％、67％、70％、73％、75％、78％、80％、83％、85％、87％、90％中的任意值或其中的任意两个值组成的范围值。
所述正极合剂层中正极活性材料颗粒尺寸的均匀性对电池的充电性能有显著的影响，正极活剂层中正极活性材料颗粒尺寸的越均匀，正极活性材料活性颗粒在大电流的充电条件下不同颗粒之间的电流密度差异越小，即表明不同颗粒之间脱锂深度一致，极化降低，进而电池的温升降低，保 证电池有较好的充电能力以及使用寿命。
实施例1
(1)正极活性材料的制备
步骤1：将正极活性材料前驱体Ni 0.52Co 0.045Mn 0.435(OH) 2和碳酸锂置于混料设备中进行充分混合，碳酸锂的锂与前驱体的摩尔比为1.04:1。
步骤2：把混合后的材料置于气氛炉进行烧结，升温区的烧结时间为6小时。恒温区的烧结温度在990℃，恒温区的烧结时间12小时，烧结过程中恒温区的气氛为氧气气氛，气氛炉恒温区氧气的浓度为30％。
步骤3：把烧结后得到的正极活性材料进行对辊破碎，然后进行气流破碎。
步骤4：将破碎后正极活性材料置于高混机中混合，混料频率为40Hz，混料时间为20min。
步骤5：将混合后的正极活性材料置于窑炉中进行二次烧结即得到成品正极活性材料。烧结温度为550℃，烧结时间为6小时。
合成的正极活性材料的(003)峰的半峰宽FWHW(003)为0.088°，(104)峰的半峰宽FWHW(104)为0.097°。合成的正极活性材料(003)峰的峰面积为Ic(003)，(104)峰的峰面积为Ic(104)，Kc＝Ic(003)/Ic(104)，Kc＝1.66。
(2)正极极片的制备
步骤1：将上述的正极活性材料、粘接剂聚偏氟乙烯、导电剂乙炔黑、导电剂碳纳米管按照质量比为97:1.5:1:0.5进行充分混合，加入N-甲基吡咯烷酮(NMP)，在搅拌机作用下搅拌均匀，获得正极活性材料、粘接剂、导电剂分散均匀的正极浆料；将正极浆料均匀涂覆于厚度为12微米的铝箔上，涂布完一面后再对另一面进行涂布，单面扣除铝箔重量的涂布面密度为16mg/cm 2。
步骤2：将涂覆后的极片经过100℃～130℃烘箱干燥。
步骤3：将烘干的极片进行辊压，通过控制辊压的压力、速度、辊棒的温度、辊压的次数，对正极合剂层采用X射线衍射测试，正极合剂层(003)峰的峰面积为If(003)，正极合剂层(104)峰的峰面积为If(104)， Kf＝If(003)/If(104)，Kf＝15.74。
(3)负极极片的制备
将负极活性材料、增稠剂羧甲基纤维素钠、粘接剂丁苯橡胶、导电剂乙炔黑按照质量比为96:0.8:1.2:2进行混合，加入去离子水，在搅拌机作用下获得负极活性材料、稠剂羧甲基纤维素钠、粘接剂丁苯橡胶、导电剂乙炔黑分散均匀负极浆料；将负极浆料均匀涂覆在一定厚度为的铜箔上，单面扣除铝箔的面密度为7.37mg/cm 2；将涂布后的极片转移至100～120℃烘箱进行干燥，对极片另一面进行相同面密度的涂布，然后经过冷压、分切得到负极极片。
(4)电解液的制备：
有机溶剂为含有碳酸亚乙酯(EC)、碳酸甲乙酯(EMC)和碳酸二乙酯(DEC)的按照质量比1:1:1进行充分混合的混合液。将锂盐LiPF 6溶解于有机溶剂中，混合均匀，获得电解液。锂盐的浓度为1.0mol/L。
(5)隔离膜的制备：
选用厚度为12μm的聚乙烯隔离膜。
(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，再卷绕成方形的裸电芯后，装入外包装，然后在进行烘烤除水，注入相应的非水电解液、封口，经静置、热冷压、化成、分容等工序后，得到成品电池。
实施例2
除正极活性材料的制备方法步骤1前驱体为Ni 0.78Co 0.03Mn 0.19(OH) 2，锂盐为氢氧化锂，步骤2烧结温度为910℃外，其他步骤与实施例1完成一致。
实施例3
除正极活性材料的制备方法步骤1前驱体为Ni 0.55Co 0.12Mn 0.33(OH) 2，步骤2恒温区的烧结温度为945℃外，其他步骤与实施例1相同。
实施例4
除正极活性材料的制备方法步骤1前驱体为Ni 0.60Co 0.10Mn 0.30(OH) 2外，其他步骤与实施例3相同。
实施例5
除正极活性材料的制备方法步骤1添加了占正极活性材料中除锂之外金属元素的摩尔总量0.4％的氧化锆添加剂以外，其他步骤与实施例4相同。
实施例6
除正极活性材料的制备方法步骤1添加了占正极活性材料中除锂之外金属元素的摩尔总量2.9％的氧化锆添加剂以外，其他步骤与实施例4相同。
实施例7
除正极活性材料的制备方法步骤1添加了占正极活性材料中除锂之外金属元素的摩尔总量0.4％的氧化锆添加剂，步骤4将破碎后的正极活性材料与占正极活性材料中除锂之外金属元素的摩尔总量0.5％的氧化铝添加剂充分混合以外，其他步骤与实施例4相同。
实施例8
除正极活性材料的制备方法步骤1添加了占正极活性材料中除锂之外金属元素的摩尔总量0.4％的氧化锆和0.1％的氧化锶添加剂，步骤4将破碎后的正极活性材料与占正极活性材料中除锂之外金属元素的摩尔总量0.5％的氧化铝添加剂充分混合以外，其他步骤与实施例4相同。
实施例9
除正极活性材料的制备方法步骤1添加了占正极活性材料中除锂之外金属元素的摩尔总量0.4％的氧化锆和0.1％的氧化锶添加剂，步骤4将破碎后的正极活性材料与占正极活性材料中除锂之外金属元素的摩尔总量0.5％的氧化铝和0.2％的氧化钨添加剂充分混合以外，他步骤与实施例4相同。
实施例10
除正极活性材料的制备方法步骤1前驱体为Ni 0.58Co 0.14Mn 0.28(OH) 2，添加了占正极活性材料中除锂之外金属元素的摩尔总量0.3％的氧化锆添加剂，步骤4将破碎后的正极活性材料与占正极活性材料中除锂之外金属元素的摩尔总量0.4％的氧化铝和0.2％的氧化钛添加剂充分混合以外，其他步骤与实施例4相同。
实施例11
除正极活性材料的制备方法步骤1前驱体为Ni 0.635Co 0.09Mn 0.275(OH) 2，锂盐为氢氧化锂，添加了占正极活性材料中除锂之外金属元素的摩尔总量0.3％的氧化锆、0.1％的氧化锶和0.1％的氧化钡添加剂，步骤4将破碎后的正极活性材料与占正极活性材料中除锂之外金属元素的摩尔总量0.9％的氧化铝和0.1％的氧化钨添加剂充分混合以外，其他步骤与实施例4相同。
实施例12
除正极活性材料的制备方法步骤1前驱体为Ni 0.68Co 0.09Mn 0.27(OH) 2，锂盐为氢氧化锂，添加了占正极活性材料中除锂之外金属元素的摩尔总量0.3％的氧化锆、0.1％的氧化锶和0.1％的氧化钡添加剂，步骤2恒温区的烧结温度为935℃，步骤4将破碎后的正极活性材料与占正极活性材料中除锂之外金属元素的摩尔总量1.1％的氧化铝和0.2％的氧化钨添加剂充分混合以外，其他步骤与实施例4相同。
实施例13
除正极活性材料的制备方法步骤1前驱体为Ni 0.72Co 0.05Mn 0.23(OH) 2，锂盐为氢氧化锂，添加了占正极活性材料中除锂之外金属元素的摩尔总量0.3％的氧化锆、0.1％的氧化锶和0.1％的氧化钡添加剂，步骤2恒温区的烧结温度为910℃，步骤4将破碎后的正极活性材料与占正极活性材料中除锂之外金属元素的摩尔总量0.7％的氧化铝和0.2％的氧化钨添加剂充分混合以外，其他步骤与实施例4相同。
实施例14
除正极活性材料的制备方法步骤1添加了占正极活性材料中除锂之外金属元素的摩尔总量0.15％的氧化锆和0.75％的氧化锶添加剂，步骤4将破碎后的正极活性材料与占正极活性材料中除锂之外金属元素的摩尔总量0.1％的氧化铝添加剂充分混合以外，其他步骤与实施例4相同。
实施例15
除正极活性材料的制备方法步骤2恒温区的烧结温度为980℃，恒温区的烧结时间为24小时外，其他步骤与实施例9相同。
实施例16
除正极活性材料的制备方法步骤2恒温区的烧结温度为925℃，恒温区的烧结时间为7小时外，其他步骤与实施例9相同。
实施例17
除正极活性材料的制备方法步骤2恒温区的烧结温度为980℃，恒温区的烧结时间为24小时外，步骤3破碎参数有调整外，其他步骤与实施例9相同。
实施例18-21
除正极极片的制备方法中步骤3辊压参数有调整外，其他步骤与实施例15相同。
对比例1
除正极活性材料的制备方法步骤1前驱体为Ni 0.46Co 0.04Mn 0.50(OH) 2外，其他步骤与实施例1相同。
对比例2
除正极活性材料的制备方法步骤1前驱体为Ni 0.60Co 0.03Mn 0.37(OH) 2外，其他步骤与实施例1相同。
对比例3
除正极活性材料的制备方法步骤1前驱体为Ni 0.82Co 0.03Mn 0.15(OH) 2，锂盐为氢氧化锂外，其他步骤与实施例1相同。
实施例1-21以及对比例1-3的具体实验参数和电池电化学性能见表1、表2和表3。
关于表1和表2中正极活性材料以及合剂层材料的参数测试方法如下：
1、正极活性材料粉体的(003)衍射峰的半峰宽为FWHW(003)以及正极活性材料粉体的(104)衍射峰的半峰宽为FWHW(104)的测试方法如下：
正极活性材料的粉体的(003)衍射峰的半峰宽为FWHW(003)以及正极活性材料粉体的(104)衍射峰的半峰宽为FWHW(104)可通过使用X射线粉末衍射仪(X'pert PRO)得到，依据X射线衍射分析法通则JIS K 0131-1996，得到X射线衍射图谱，扣除X射线衍射图谱的背底以及Kα2。其中，FWHW(003)为(003)特征衍射峰高度一半处的峰宽度， FWHW(104)为(104)特征衍射峰高度一半处的峰宽度，单位为°。
2、正极活性材料(003)衍射峰的峰面积为Ic(003)以及正极活性材料(104)衍射峰的峰面积为Ic(104)的比值Kc的测试方法如下：
正极活性材料的粉体Kc值可通过使用X射线粉末衍射仪(X'pert PRO)得到，依据X射线衍射分析法通则JIS K 0131-1996，得到X射线衍射图谱，Kc＝I(003)/I(104)，其中，I(003)为(003)特征衍射峰的峰面积，I(104)为(104)特征衍射峰的峰面积。具体地，正极活性材料的粉体Kc值的测试方法为：将一定质量正极活性材料粉末置于X射线粉末衍射仪中，通过X射线衍射分析法得到(003)晶面衍射峰的峰面积以及(104)晶面衍射峰的峰面积，进而得到正极活性材料的粉体Kc值。
3、正极合剂层(003)衍射峰的峰面积为Ic(003)以及正极合剂层(104)衍射峰的峰面积为Ic(104)的比值Kc的测试方法如下：
正极合剂层的Kf值可通过使用X射线粉末衍射仪(X'pert PRO)得到，依据X射线衍射分析法通则JIS K 0131-1996，得到X射线衍射图谱，Kc＝I(003)/I(104)，其中，I(003)为(003)特征衍射峰的峰面积，I(104)为(104)特征衍射峰的峰面积。具体地，正极合剂层的Kf值的测试方法为：将正极极片直接置于X射线粉末衍射仪中，通过X射线衍射分析法得到(003)晶面衍射峰的峰面积以及(104)晶面衍射峰的峰面积，进而得到正极合剂层的粉体Kf值。
关于表3中电池电化学性能的测试方法如下：
1、正极活性材料克容量测试
在25℃±3℃的测试环境下，将实施例和对比例制备得到的锂离子电池以1/3C倍率充电至4.35V、以1/3C倍率放电至2.80V，记录放电容量，将放电容量除以正极极片中活性材料的质量既可以得到正极活性材料的克容量。正极活性材料的克容量越高，表明电池可以提供的能量密度越高，电池的性能越优。
2、电池循环1000周的容量保持率测试
在25℃±3℃下，将实施例和对比例制备得到的锂离子电池按照1C倍率充电至4.35V、以1C倍率放电至2.80的充放电制度循环1000周，记录每一圈的充电容量和放电容量，将第1000周的放电容量比上第1周的放电 容量，所得到的比例即为电池循环1000周的容量保持率。电池的循环容量保持率越高，表明电池的抗容量衰减的能力越强，电池的性能越优。
3、电池循环1000周负极极片Mn离子和Ni离子的溶出总量测试
将将实施例和对比例制备得到的锂离子电池按照1C倍率充电至4.35V、以1C倍率放电至2.80的充放电制度循环1000周，然后按照1C的倍率放电至2.80V，将电池拆解后，取出电池中的负极极片，用DMC浸泡12小时，除去负极极片表面残留的杂质，再在80℃烘箱中烘烤2小时，除去DMC以及残留的电解液。然后采用EPA6010D电感耦合等离子体原子发射光谱法测试负极极片中Mn元素的含量和Ni元素的含量，这两个含量之和即为电池循环1000周负极极片Mn离子和Ni离子的溶出总量。负极极片Mn离子和Ni离子的溶出总量越低，表明正极材料的结构越稳定，相应的电池也具备更长的使用寿命。
4、电池循环1000周的阻抗增加幅度测试
在25℃±2℃下，将实施例和对比例制备得到的锂离子电池以1C倍率放电至2.8V、以1C倍率充电至4.35V、再以1C的倍率放电至2.8V，记录放电容量C 1，再将制备得到的锂离子电池以1C 1的电流充电至4.35V，然后以1C 1的电流放电30分钟后静置180分钟，记录静置后电池的电压V 1，再用5C 1的电流放电10秒，记录电压放电10秒末端的电压V 2，初始的阻抗R1＝(V 2-V 1)/5C 1。将制备得到的锂离子电池按照1C倍率充电至4.35V、以1C倍率放电至2.80的充放电制度循环1000周。然后把循环1000周的电池以1C 1倍率放电至2.8V、以1C 1倍率充电至4.35V、再以1C 1的倍率放电至2.8V，记录放电容量C 2，再将制备得到的锂离子电池以1C 2的电流充电至4.35V，然后以1C 2的电流放电30分钟后静置180分钟，记录静置后电池的电压V 3，再用5C 2的电流放电10秒，记录电压放电10秒末端的电压V 4，循环1000周的阻抗R2＝(V 4-V 3)/5C 2。循环1000周的阻抗增加幅度ΔR＝(R 2-R 1)/R 1。电池循环1000周的阻抗增加幅度越低，表明电池使用过程中的充电能力衰减越低，即电池拥有更优的充电能力。
表1 实施例1-14的正极活性材料的特征
Figure PCTCN2022139467-appb-000001
Figure PCTCN2022139467-appb-000002
表2 实施例1-15以及对比例1-3的正极活性材料的特征
Figure PCTCN2022139467-appb-000003
Figure PCTCN2022139467-appb-000004
表3 实施例1-21以及对比例1-3的正极特征及电池测试结果
Figure PCTCN2022139467-appb-000005
Figure PCTCN2022139467-appb-000006
由表1、表2和表3中的数据可以得出如下结论：
实施例1与对比例1、对比例2对比，实施例1制备的电池的循环1000周的容量保持率为83.1％，高于对比例1的61.2％和对比例2的66.1％，表明实施例1制备的电池拥有更优的循环稳定性；实施例1制备的电池的循环1000周的阻抗增加幅度为35.2％，低于对比例1的92.6％和对比例2的86.5％，表明实施例1制备的电池拥有更优的抵抗功率衰减的性能，实施例1的优异性能得益于其钴、锰的摩尔含量设计，导致其正极活性材料有更低的Mn离子和Ni离子的溶出总量。实施例1制备的电池的循环1000周后负极极片Mn离子和Ni离子溶出的总量为342.1ppm，远低于对比例1的667.3ppm和对比例2的607.9ppm。
实施例2与对比例3对比，实施例2制备的电池的循环1000周的容量保持率为77.5％，高于对比例3的34.2％，表明实施例2制备的电池拥有更优的循环稳定性；实施例2制备的电池的循环1000周的阻抗增加幅度为42.3％，低于对比例3的126.8％，表明实施例2制备的电池拥有更优的抵抗功率衰减的性能，实施例2的优异性能得益于其钴、锰的摩尔含量设计，导致其正极活性材料有更低的Mn离子和Ni离子的溶出总量。实施例2制备的电池的循环1000周后负极极片Mn离子和Ni离子溶出的总量为421.7ppm，远低于对比例3的826.3ppm。
实施例1与实施例3对比，实施例3制备的电池的循环1000周的容量保持率为84.3％，高于实施例3的83.1％，表明实施例3制备的电池拥有更优的循环稳定性；实施例3制备的电池的循环1000周的阻抗增加幅度为28.7％，低于实施例1的35.2％，表明实施例3制备的电池拥有更优的抵抗功率衰减的性能，实施例3的优异性能得益于其更优钴和锰的摩尔含量比例设计，导致其正极活性材料有更低的Mn离子和Ni离子的溶出总量。实施例3制备的电池的循环1000周后负极极片Mn离子和Ni离子溶出的总量为285.5ppm，低于实施例3的342.1ppm。
实施例5与实施例4对比，实施例5制备的电池的循环1000周的容量保持率为88.6％，高于实施例4的86.5％，表明实施例5制备的电池拥有 更优的循环稳定性；实施例5制备的电池的循环1000周的阻抗增加幅度为25.1％，低于实施例4的31.3％，表明实施例3制备的电池拥有更优的抵抗功率衰减的性能，实施例5的优异性能得益于其适量的添加元素Zr的引入提升了材料的结构稳定性，导致其正极活性材料有更低的Mn离子和Ni离子的溶出总量。实施例5制备的电池的循环1000周后负极极片Mn离子和Ni离子溶出的总量为241.3ppm，低于实施例4的292.0ppm。
实施例6与实施例5对比，实施例6制备电池的正极克容量为178.6mAh/g，远低于实施例5的186.5mAh/g，表明过多的添加Zr元素会影响电池的能量密度。
实施例7与实施例5对比，实施例7制备的电池的循环1000周的容量保持率为93.7％，高于实施例5的88.6％，表明实施例7制备的电池拥有更优的循环稳定性；实施例7制备的电池的循环1000周的阻抗增加幅度为16.7％，低于实施例5的25.1％，表明实施例7制备的电池拥有更优的抵抗功率衰减的性能，实施例7的优异性能得益于其适量的添加元素Zr和Al的共同引入提升了材料的结构稳定性，导致其正极活性材料有更低的Mn离子和Ni离子的溶出总量。实施例7制备的电池的循环1000周后负极极片Mn离子和Ni离子溶出的总量为191.4ppm，低于实施例5的241.3ppm。
实施例8、实施例9和实施例10与实施例7对比，实施例8、实施例9和实施例10制备的电池的循环1000周的容量保持率分别为94.9％、96.2％和95.8％，高于实施例7的93.7％，表明实施例8、实施例9和实施例10制备的电池拥有更优的循环稳定性；实施例8、实施例9和实施例10制备的电池的循环1000周的阻抗增加幅度分别为12.6％、6.8％和10.7％，低于实施例7的16.7％，表明实施例8、实施例9和实施例10制备的电池拥有更优的抵抗功率衰减的性能，实施例8、实施例9和实施例10的优异性能得益于其适量的添加元素Zr和Al的共同引入基础上还可选的添加了Ti、Sr、W元素，进一步提升了材料的结构稳定性，使正极活性材料有更低的Mn离子和Ni离子的溶出总量。实施例8、实施例9和实施例10制备的电池的循环1000周后负极极片Mn离子和Ni离子溶出的总量分别为153.7ppm、126.1ppm和137.4ppm，低于实施例7的191.4ppm。
实施例11、实施例12和实施例13进一步表明，通过对钴、锰摩尔比例的设计、添加剂元素的种类和含量的设计，合成的正极活性材料制备的电池拥有高的正极材料克容量发挥、高的容量保持率以及更优的抵抗功率衰减的性能。实施例11、实施例12和实施例13的正极克容量分别为190.7mAh/g、196.4mAh/g和196.1mAh/g，循环1000周的容量保持率分别为92.5％、92.1％和91.5％，循环1000周的阻抗增加幅度分别为14.5％、13.8％和16.7％。
实施例14与实施例8对比，实施例8制备的电池的循环1000周的容量保持率为94.9％，高于实施例14的87.3％，表明实施例8制备的电池拥有更优的循环稳定性；实施例8制备的电池的循环1000周的阻抗增加幅度为12.6％，低于实施例1的25.1％，表明实施例8制备的电池拥有更优的抵抗功率衰减的性能，实施例8的优异性能得益于其添加元素Zr和Al的引入量在合适的范围可以提升材料的结构稳定性，导致其正极活性材料有更低的Mn离子和Ni离子的溶出总量。实施例8制备的电池的循环1000周后负极极片Mn离子和Ni离子溶出的总量为153.7ppm，低于实施例5的224.3ppm。
实施例15与实施例9对比，实施例9制备的电池的循环1000周的容量保持率为96.2％，高于实施例15的86.3％，表明实施例9制备的电池拥有更优的循环稳定性；实施例9制备的电池的循环1000周的阻抗增加幅度为6.8％，低于实施例15的35.5％，表明实施例9制备的电池拥有更优的抵抗功率衰减的性能，实施例9的优异性能得益于其合适的FWHW(003)和FWHW(104)设计可以提高材料的结构稳定性，导致其正极活性材料有更低的Mn离子和Ni离子的溶出总量。实施例9制备的电池的循环1000周后负极极片Mn离子和Ni离子溶出的总量为126.1ppm，低于对比例15的273.5ppm。同时，FWHW(003)和FWHW(104)过低时，表明正极活性材料颗粒的生长过充分，导致动力学的降低，影响正极活性材料的克容量，实施例15与实施9对比，实施例9制备电池的正极材料克容量为188.6mAh/g，远远高于实施例15的174.2mAh/g。
实施例16与实施例9对比，实施例9制备的电池的循环1000周的容量保持率为96.2％，高于实施例16的87.9％，表明实施例9制备的电池拥 有更优的循环稳定性；实施例9制备的电池的循环1000周的阻抗增加幅度为6.8％，低于实施例16的29.6％，表明实施例9制备的电池拥有更优的抵抗功率衰减的性能，实施例9的优异性能得益于其合适的FWHW(003)和FWHW(104)设计可以提高材料的结构稳定性，导致其正极活性材料有更低的Mn离子和Ni离子的溶出总量。实施例9制备的电池的循环1000周后负极极片Mn离子和Ni离子溶出的总量为126.1ppm，低于实施例16的237.9ppm。
实施例17-实施例21与实施例9对比，实施例9制备的电池的循环1000周的容量保持率为96.2％，高于实施例17的77.6％、实施例18的81.5％，表明实施例9制备的电池拥有更优的循环稳定性；实施例9制备的电池的循环1000周的阻抗增加幅度为6.8％，低于实施例17的38.8％和实施例18的32.3％，表明实施例9制备的电池拥有更优的抵抗功率衰减的性能，实施例9的优异性能得益于其合适的正极活性材料Kc值以及正极合剂层Kf值设计，导致其正极活性材料有更低的Mn离子和Ni离子的溶出总量。实施例9制备的电池的循环1000周后负极极片Mn离子和Ni离子溶出的总量为126.1ppm，低于对实施例17的358.1ppm和实施例18的235.8ppm。
以上步骤所提供的介绍，只是用于帮助理解本申请的方法、结构及核心思想。对于本技术领域内的普通技术人员来说，在不脱离本申请原理的前提下，还可以对本申请进行若干改进和修饰，这些改进和修饰也同样属于本申请权利要求保护范围之内。
工业应用
本申请具有如下有益技术效果：
1、可以降低正极活性材料中的过渡金属元素镍、锰、钴的溶解，提高电池的充电能力、循环寿命和安全性能。对于正极活性材料，材料中Ni含量较高，正极活性材料的脱嵌锂深度增加，材料的结构稳定差，Mn含量增加时，由于Mn溶解后易于破坏负极的表面保护膜，导致阻抗的增加，提升析锂风险，降低电池的充电能力、循环寿命和安全性能。通过合理的设计添加元素的量和成分，可以抑制正极活性材料在使用过程中的金属离子溶解，改善电池的充电能力、循环寿命和安全性能。
2、可以降低正极颗粒在正极极片加工过程产生的微裂纹，同时保证正极拥有较好的充电能力、循环寿命和安全性能。适当的正极极片压实和正极粉体压实比值可以保证正极活性材料颗粒之间、正极活性材料颗粒与导电剂之间的电接触良好，同时可以降低正极活性材料颗粒滑移裂纹的数量。正极极片压实和正极粉体压实比值较低时，正极颗粒与颗粒之间、正极颗粒与导电剂之间的电接触面积不足，导致正极合剂层欧姆内阻较大，影响电池的充电性能；极极片压实和正极粉体压实比例较高时，正极合剂层的压实较高，容易导致正极活性材料颗粒形成滑移裂纹，导致电解液的恶化以及过渡金属的溶出，影响充电能力、循环寿命和安全性能。

Claims (12)

  1. 一种正极活性材料，包括锂镍钴锰氧化物；
    所述锂镍钴锰氧化物中，以镍元素、钴元素和锰元素的摩尔总量为100％计，所述锰元素的摩尔量记为m％，所述钴元素的摩尔量记为n％，满足下述条件：20<n+m<50，且0.1<n/m<0.6；所述正极活性材料的(003)峰的半峰宽记为FWHW(003)，所述正极活性材料的(104)峰的半峰宽记为FWHW(104)；所述FWHW(003)和所述FWHW(104)满足如下条件：0.4≤FWHW(003)/FWHW(104)≤2.0。
  2. 根据权利要求1所述的正极活性材料，其特征在于：所述m和所述n满足下述条件中任一种：
    (ⅰ)19≤m<43.5；
    (ⅱ)3.0≤n≤12；
    (ⅲ)0.10≤n/m≤0.502。
  3. 根据权利要求1或2所述的正极活性材料，其特征在于：所述正极活性材料还包括M元素，所述M元素包括Zr元素，以及Al、Mg、Ti、Y、Sr、Y、Mo、Nb、Sn、Ba、La、Ce和W元素中的至少一种；
    以所述镍元素、所述钴元素和所述锰元素的摩尔总量为100％计，所述M元素的摩尔量与所述镍元素、所述钴元素和所述锰元素的摩尔总量的百分比记为x％，0.1≤x≤2.5。
  4. 根据权利要求3所述的正极活性材料，其特征在于：所述M元素包含Zr元素、Al元素，以及Mg、Ti、Y、Sr、Y、Mo、Nb、Sn、Ba、La、Ce、W元素中的至少一种，其中，所述M元素的摩尔含量记为x％，Zr元素的摩尔含量记为x1％，Al元素的摩尔含量记为x2％，x、x1和x2满足下述条件中任一种：
    (ⅳ)0.20≤x1≤0.45；
    (ⅴ)0.15≤x2≤1.5；
    (ⅵ)0.2≤x1/x2≤1；
    (ⅶ)0<(x-x1-x2)/x<0.5。
  5. 根据权利要求1或2所述的正极活性材料，其特征在于：所述正极活性材料的(003)峰的半峰宽记为FWHW(003)，所述正极活性材料的(104)峰的半峰宽记为FWHW(104)；
    所述FWHW(003)的范围为0.06°～0.15°；
    所述FWHW(104)的范围为0.06～0.15°。
  6. 根据权利要求1或2所述的正极活性材料，其特征在于：所述正极活性材料的(003)峰的峰面积记为Ic(003)，(104)峰的峰面积记为Ic(104)，Kc为Ic(003)/Ic(104)，1≤Kc≤2。
  7. 根据权利要求3所述的正极活性材料，其特征在于：所述正极活性材料包含Li aNi bCo m/100Mn n/100M x/100O 2，0.80≤a≤1.10，0.4<b<0.8，20<n+m<50，且0.1<n/m<0.6，0.1≤x≤2.5，M包括Zr，以及Al、Mg、Ti、Y、Sr、Y、Mo、Nb、Sn、Ba、La、Ce和W中的至少一种。
  8. 一种二次电池，包括正极；其特征在于：所述正极包括正极集流体和设置于所述正极集流体上的正极合剂层，所述正极合剂层包含权利要求1-7中任一项所述的正极活性材料。
  9. 根据权利要求8所述的二次电池，其特征在于：所述正极合剂层的(003)峰的峰面积记为If(003)，(104)峰的峰面积记为If(104)，Kf为If(003)/If(104)，10≤Kf≤20。
  10. 根据权利要求8所述的二次电池，其特征在于：所述正极合剂层的(003)峰的峰面积记为If(003)，(104)峰的峰面积记为If(104)，Kf为If(003)/If(104)，6≤Kf/Kc≤20。
  11. 根据权利要求8所述的二次电池，其特征在于：所述正极合剂层中所述正极活性材料形成的颗粒尺寸在1微米-3微米的个数占总的颗粒个数的比例大于60％。
  12. 一种用电装置，包含权利要求8-11中任一项所述的二次电池。
PCT/CN2022/139467 2022-12-01 2022-12-16 一种正极活性材料及锂离子电池 Ceased WO2024113430A1 (zh)

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