WO2024197831A1 - 一种正极材料、包含该正极材料的电化学装置和用电装置 - Google Patents

一种正极材料、包含该正极材料的电化学装置和用电装置 Download PDF

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WO2024197831A1
WO2024197831A1 PCT/CN2023/085543 CN2023085543W WO2024197831A1 WO 2024197831 A1 WO2024197831 A1 WO 2024197831A1 CN 2023085543 W CN2023085543 W CN 2023085543W WO 2024197831 A1 WO2024197831 A1 WO 2024197831A1
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positive electrode
present application
electrode material
cobalt oxide
lithium
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French (fr)
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刘小浪
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Ningde Amperex Technology Ltd
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Ningde Amperex Technology Ltd
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Priority to PCT/CN2023/085543 priority Critical patent/WO2024197831A1/zh
Priority to CN202380013016.3A priority patent/CN117999674B/zh
Priority to EP23929416.8A priority patent/EP4693488A1/en
Publication of WO2024197831A1 publication Critical patent/WO2024197831A1/zh
Priority to US19/343,423 priority patent/US20260031348A1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • C01G51/00—Compounds of cobalt
    • C01G51/40—Complex oxides containing cobalt and at least one other metal element
    • C01G51/42—Complex oxides containing cobalt and at least one other metal element containing alkali metals, e.g. LiCoO2
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G51/00—Compounds of cobalt
    • C01G51/40—Complex oxides containing cobalt and at least one other metal element
    • C01G51/42—Complex oxides containing cobalt and at least one other metal element containing alkali metals, e.g. LiCoO2
    • C01G51/44—Complex oxides containing cobalt and at least one other metal element containing alkali metals, e.g. LiCoO2 containing manganese
    • C01G51/50—Complex oxides containing cobalt and at least one other metal element containing alkali metals, e.g. LiCoO2 containing manganese of the type (MnO2)n-, e.g. Li(CoxMn1-x)O2 or Li(MyCoxMn1-x-y)O2
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G51/00—Compounds of cobalt
    • C01G51/40—Complex oxides containing cobalt and at least one other metal element
    • C01G51/70—Complex oxides containing cobalt and at least one other metal element containing rare earths, e.g. LaCoO3 
    • 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
    • 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
    • C01G53/66—Complex oxides containing nickel and at least one other metal element containing alkaline earth metals, e.g. SrNiO3 or SrNiO2
    • 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
    • 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
    • C01P2002/76—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by a space-group or by other symmetry indications
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
    • C01P2002/82—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by IR- or Raman-data
    • 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
    • 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 field of electrochemical technology, and in particular to a positive electrode material, an electrochemical device containing the positive electrode material, and an electrical device.
  • Lithium-ion batteries have the characteristics of high specific energy, high operating voltage, low self-discharge rate, small size and light weight, and are widely used in consumer electronics and other fields.
  • the purpose of the present application is to provide a positive electrode material, an electrochemical device and an electrical device containing the positive electrode material, so as to improve the cycle performance of the electrochemical device.
  • the specific technical solution is as follows:
  • the first aspect of the present application provides a positive electrode material, which includes lithium cobalt oxide having a P63mc crystal structure, wherein in the Raman spectrum of the positive electrode material, the peak intensity of the characteristic peak in the range of 490 cm -1 ⁇ 5 cm -1 is I 1 , and the peak intensity of the characteristic peak in the range of 592 cm -1 ⁇ 5 cm -1 is I 2 , satisfying 1 ⁇ I 2 /I 1 ⁇ 5.
  • the positive electrode material of the present application can support a transition metal layer, thereby reducing the collapse of the transition metal layer, improving the structural stability of the positive electrode material in a high delithiation state, and thus improving the cycle stability of the electrochemical device.
  • the positive electrode material exhibits good cycle stability, thereby improving the cycle performance of the electrochemical device.
  • the lithium cobalt oxide contains an alkaline earth metal element M, and the Li site of the lithium cobalt oxide is doped with the M element.
  • the M element is doped into the Li site to form a pillar effect, which can support the transition metal layer in a high delithiation state and reduce the collapse of the transition metal layer, thereby improving the structural stability of the positive electrode material in a high delithiation state.
  • the M element includes at least one of Ca or Mg.
  • the M element can remain relatively stable, effectively doped into the Li site to form a pillar effect, and the positive electrode material exhibits good cycle stability.
  • the lithium cobalt oxide further comprises a Na element and a metal element Q;
  • the Q element comprises At least one of Al, Zr, Ni, Mn, Y, Nb, La, Fe, Cu, Cr, Ti, W, Lu or Yb; based on the molar amount of the metal elements other than Li, Na and M in the lithium cobalt oxide, the molar percentage of the Na element in the lithium cobalt oxide is 0.5% to 5%, and the molar percentage of the Q element in the lithium cobalt oxide is 2% to 10%.
  • the Dv50 of the positive electrode material is 5 ⁇ m to 25 ⁇ m. In this case, the positive electrode material has good cycle performance.
  • the second aspect of the present application provides an electrochemical device, which includes a positive electrode sheet, the positive electrode sheet includes a positive electrode active material layer, wherein the positive electrode active material layer includes the positive electrode material in any of the above embodiments.
  • the positive electrode material provided in the present application has good cycle stability, so that the electrochemical device provided in the present application has good cycle performance.
  • the charge cut-off voltage of the electrochemical device is not less than 4.50 V. At this time, the electrochemical device has a higher reversible capacity and good cycle performance.
  • the third aspect of the present application provides an electrical device, which includes the electrochemical device in any of the above embodiments.
  • the electrochemical device provided in the present application has good cycle performance, so the electrical device provided in the present application has a long service life.
  • the present application provides a positive electrode material, an electrochemical device and an electrical device comprising the positive electrode material, wherein the positive electrode material comprises lithium cobalt oxide having a P63mc crystal structure, and in the Raman spectrum of the positive electrode material, the peak intensity of the characteristic peak within the range of 490 cm -1 ⁇ 5 cm -1 is I 1 , and the peak intensity of the characteristic peak within the range of 592 cm -1 ⁇ 5 cm -1 is I 2 , satisfying 1 ⁇ I 2 /I 1 ⁇ 5.
  • the positive electrode material of the present application can support the transition metal layer in a highly delithiated state, thereby reducing the collapse of the transition metal layer, improving the structural stability of the positive electrode material in a highly delithiated state, and thus improving the cycle performance of the electrochemical device.
  • FIG. 1 is a Raman spectrum diagram of Examples 1 to 3 and Comparative Examples 1 to 2 of the present application.
  • a lithium-ion battery is used as an example of an electrochemical device to explain the present application, but the electrochemical device of the present application is not limited to a lithium-ion battery.
  • the first aspect of the present application provides a positive electrode material, which includes a lithium cobalt oxide having a P63mc crystal structure.
  • the peak intensity of the characteristic peak in the range of 490 cm -1 ⁇ 5 cm -1 is I 1
  • the peak intensity of the characteristic peak in the range of 592 cm -1 ⁇ 5 cm -1 is I 2 , satisfying 1 ⁇ I 2 /I 1 ⁇ 5.
  • the positive electrode material in the present application can support the transition metal layer in a highly delithiated state, thereby reducing the collapse of the transition metal layer, improving the structural stability of the positive electrode material in a highly delithiated state, and thus improving the cycle stability of the lithium ion battery.
  • the high delithiation state in this application means that when the charge cut-off voltage is ⁇ 4.55V, the positive electrode material is in a high delithiation state, and the amount of delithiation of the positive electrode material is generally ⁇ 0.7 mol compared to the material in the initial full discharge state.
  • the composition of the material in the initial full discharge state is Li 0.9 CoO 2
  • the composition of the positive electrode material when the delithiation amount is 0.7 mol becomes Li 0.2 CoO 2 .
  • the lithium cobalt oxide contains an alkaline earth metal element M, and the Li site of the lithium cobalt oxide is doped with the M element.
  • the M element doped into the Li site can form a pillar effect, which can support the transition metal layer in a high delithiation state, reduce the collapse of the transition metal layer, and improve the structural stability of the positive electrode material in a high delithiation state, thereby improving the cycle performance of the lithium ion battery.
  • the molar percentage of the M element in the lithium cobalt oxide is 0.5% to 5%.
  • the M element includes at least one of Ca or Mg.
  • the M element can remain relatively stable, effectively doped into the Li site to form a pillar effect, and the lithium-ion battery exhibits good cycle stability.
  • the lithium cobalt oxide further comprises a Na element and a metal element Q;
  • the Q element comprises at least one of Al, Zr, Ni, Mn, Y, Nb, La, Fe, Cu, Cr, Ti, W, Lu or Yb; based on the molar amount of the metal elements other than Li, Na and M in the lithium cobalt oxide, the molar percentage of the Na element in the lithium cobalt oxide is 0.5% to 5%, and the molar percentage of the Q element in the lithium cobalt oxide is 2% to 10%, comprising the positive electrode material
  • the lithium-ion batteries showed good cycling performance.
  • the general formula of lithium cobalt oxide is NaaLibMyCo1 -zQzO2 ⁇ nTn , wherein 0 ⁇ a ⁇ 0.05, 0.65 ⁇ b ⁇ 1.1, 0 ⁇ y ⁇ 0.05, 0 ⁇ z ⁇ 0.1, 0 ⁇ n ⁇ 0.1, M element is an alkaline earth metal element, Q element includes at least one of Al, Zr, Ni, Mn, Y, Nb, La, Fe, Cu, Cr, Ti, W, Lu or Yb, T element is a halogen element, and T element includes at least one of F, Cl, Br or I.
  • the Dv50 of the positive electrode material is 5 ⁇ m to 25 ⁇ m.
  • the lithium-ion battery has good cycle performance.
  • Dv50 refers to the particle size of 50% of the particles in the volume distribution of the positive electrode material.
  • the preparation method of the positive electrode material may include but is not limited to the following steps:
  • Step 1 adding a soluble cobalt salt and a metal salt containing a doping element Q to a solvent in proportion to form a uniform mixed solution, then adding a precipitant and a complexing agent, adjusting the pH to 5 to 9, forming a homogeneous precipitate, and then sintering, crushing and screening the precipitate to obtain a metal oxide material;
  • Step 2 weighing the metal oxide material, the sodium-containing compound and the compound containing the doping element M in proportion and mixing them evenly, and keeping the mixture at a temperature of 750° C. to 1050° C. for 24 to 72 hours to obtain a sodium cobalt oxide with a P63mc structure;
  • Step 3 Using sodium cobalt oxide with a P63mc structure as a precursor material, mixing it evenly with a lithium-containing compound, loading it into a corundum crucible, and reacting it in a solid phase at a temperature of 220° C. to 280° C. for 2 to 8 hours, and obtaining a mixture containing a lithium cobalt oxide positive electrode material after cooling;
  • Step 4 crush the mixture material in step 3, wash it with deionized water for multiple times to remove the soluble sodium salt and lithium salt in the mixture, and then filter, dry and sieve the residual powder to obtain a lithium cobalt oxide positive electrode material.
  • the soluble cobalt salt and the metal salt containing the doping element are at least one of chloride, acetate, sulfate or nitrate.
  • the soluble cobalt salt includes cobalt chloride, cobalt acetate, cobalt nitrate, and cobalt sulfate;
  • the metal salt containing the doping element includes nickel nitrate, manganese nitrate, and yttrium nitrate;
  • the sodium-containing compound is at least one of Na 2 O, Na 2 O 2 , Na 2 CO 3 or NaOH, preferably Na 2 O and Na 2 CO 3 ;
  • the compound containing the doping element M is preferably a chloride and a carbonate of the element M, for example, including calcium chloride, calcium carbonate, and magnesium carbonate;
  • the present application has no special restrictions on the mixing ratio of the soluble cobalt salt and the metal salt containing the doping element Q, as long as the purpose of the present application can be achieved, and they can
  • the soluble cobalt salt and the metal salt containing the doping element Q are mixed according to 1: (0.02 to 0.11); the present application has no special restrictions on the mixing ratio of the soluble cobalt salt and the metal salt containing the doping element Q.
  • the complexing agent there is no particular limitation on the complexing agent, as long as the purpose of the present application can be achieved.
  • the precipitant includes ammonium carbonate and ammonium bicarbonate
  • the complexing agent includes ammonia water and sodium hydroxide
  • the amount of the precipitant and the complexing agent added is no particular limitation on the amount of the precipitant and the complexing agent added, as long as the purpose of the present application can be achieved.
  • the amount of the precipitant added is 1 to 2.5 times, and the amount of the complexing agent added is 1 to 1.5 times.
  • the present application has no particular limitation on the sintering temperature, for example, the sintering temperature can be 450°C to 700°C; the present application can use a jet mill device for crushing and a vibrating screen device for particle size screening, so as to regulate the particle size of the metal oxide material.
  • step 2 the present application has no particular restriction on the mixing ratio of the metal oxide material, the sodium-containing compound and the compound containing the doping element M, and they can be added according to the designed ratio.
  • the present application has no particular restrictions on the lithium-containing compound, as long as it can achieve the purpose of the present application.
  • the lithium-containing compound includes but is not limited to lithium sulfate, lithium carbonate, lithium nitrate, lithium halide, lithium carboxylate, lithium squarate, lithium alcoholate, etc.
  • the present application does not particularly limit the method for regulating the peak intensities I1 and I2 .
  • I2 generally increases with the increase of the Co-O bending vibration intensity
  • I1 generally increases with the increase of the Co-O stretching vibration intensity.
  • the bending and stretching vibration intensity of the Co-O bond can be regulated by regulating the sintering process and doping, thereby regulating the ratio range of I1 to I2 .
  • the second aspect of the present application provides an electrochemical device, which includes a positive electrode sheet, the positive electrode sheet includes a positive electrode active material layer, wherein the positive electrode active material layer includes the positive electrode material in any of the above embodiments.
  • the positive electrode material provided in the present application has good cycle stability, so that the electrochemical device provided in the present application has good cycle performance.
  • the charge cut-off voltage of the electrochemical device is not less than 4.50 V. At this time, the electrochemical device has a higher reversible capacity and good cycle performance.
  • the electrochemical device of the present application includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte.
  • the positive electrode sheet includes a positive current collector and a positive active material layer.
  • the present application has no special restrictions on the positive current collector, as long as the purpose of the present application can be achieved.
  • the positive current collector may include aluminum foil, aluminum alloy foil or a composite current collector, etc.
  • the thickness of the positive current collector is 5 ⁇ m to 20 ⁇ m, preferably 6 ⁇ m to 18 ⁇ m.
  • the thickness of the single-sided positive active material layer is 30 ⁇ m to 120 ⁇ m.
  • the positive active material layer can be arranged on one surface in the thickness direction of the positive current collector, or on two surfaces in the thickness direction of the positive current collector.
  • the positive active material layer may also include a conductive agent and a binder.
  • the present application has no particular limitation on the type of binder in the positive electrode active material layer, as long as the purpose of the present application can be achieved.
  • the binder may include but is not limited to polyvinylidene fluoride, copolymer of vinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone ...
  • At least one of polyolefin ether, polymethyl methacrylate, polytetrafluoroethylene or polyhexafluoropropylene is not limited to conductive carbon black (Super P), carbon nanotubes (CNTs), carbon fibers, flake graphite, Ketjen black, graphene, metal materials or conductive polymers.
  • the above-mentioned carbon nanotubes may include but are not limited to single-walled carbon nanotubes and/or multi-walled carbon nanotubes.
  • the above-mentioned carbon fibers may include but are not limited to vapor-grown carbon fibers (VGCF) and/or nano-carbon fibers.
  • the above-mentioned metal materials may include but are not limited to metal powders and/or metal fibers, specifically, the metal may include but are not limited to at least one of copper, nickel, aluminum or silver.
  • the above-mentioned conductive polymers may include but are not limited to at least one of polyphenylene derivatives, polyaniline, polythiophene, polyacetylene or polypyrrole.
  • the present application has no particular restrictions on the mass ratio of the positive electrode active material, the conductive agent, and the binder in the positive electrode active material layer. Those skilled in the art can choose according to actual needs, as long as the purpose of the present application can be achieved.
  • the present application has no particular restrictions on the negative electrode sheet, as long as the purpose of the present application can be achieved.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer.
  • the present application has no particular restrictions on the negative electrode current collector, as long as the purpose of the present application can be achieved.
  • the negative electrode current collector may include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, foamed nickel or foamed copper, etc.
  • the negative electrode active material layer of the present application includes a negative electrode active material.
  • the present application has no particular restrictions on the type of negative electrode active material, as long as the purpose of the present application can be achieved.
  • the negative electrode active material may include natural graphite, artificial graphite, mesophase microcarbon beads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO x (0 ⁇ x ⁇ 2), Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO 2 , spinel structured lithium titanate Li 4 Ti 5 O 12 , Li-Al alloy or at least one of metallic lithium.
  • MCMB mesophase microcarbon beads
  • the thickness of the negative electrode current collector and the negative electrode active material layer there is no particular restriction on the thickness of the negative electrode current collector and the negative electrode active material layer, as long as the purpose of the present application can be achieved.
  • the thickness of the negative electrode current collector is 6 ⁇ m to 10 ⁇ m
  • the thickness of the negative electrode active material layer is 30 ⁇ m to 130 ⁇ m.
  • the negative electrode active material layer may also include at least one of a conductive agent, a stabilizer, and a binder.
  • a conductive agent e.g., a conductive agent
  • a stabilizer e.g., a binder
  • the present application does not particularly restrict the types of conductive agents, stabilizers, and binders in the negative electrode active material layer, as long as the purpose of the present application can be achieved.
  • the present application does not particularly restrict the mass ratio of the negative electrode active material, conductive agent, stabilizer, and binder in the negative electrode active material layer, as long as the purpose of the present application can be achieved.
  • the electrochemical device of the present application also includes a diaphragm.
  • the present application has no special restrictions on the diaphragm, as long as the purpose of the present application can be achieved.
  • it may include but is not limited to polyethylene (PE), polypropylene (PP), polytetrafluoroethylene-based polyolefin (PO)-type diaphragms, polyester films (such as polyethylene terephthalate (PET) films), cellulose films, polyimide films (PI), polyamide films (PA), spandex, aramid films, woven films, non-woven films (non-woven fabrics), microporous films, composite films, diaphragm paper, rolled films or spun films. At least one of them is preferably PP.
  • the diaphragm of the present application may have a porous structure, and the size of the pore size is not particularly limited, as long as the purpose of the present application can be achieved.
  • the size of the pore size may be 0.01 ⁇ m.
  • the thickness of the separator is not particularly limited as long as the purpose of the present application can be achieved.
  • the thickness may be 5 ⁇ m to 500 ⁇ m.
  • the inorganic layer may include, but is not limited to, inorganic particles and inorganic layer binders.
  • the present application has no particular restrictions on inorganic particles, as long as the purpose of the present application can be achieved.
  • it may include, but is not limited to, at least one of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate.
  • the polymer layer contains a polymer, and the material of the polymer may include, but is not limited to, at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylic acid salt, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or polyvinylidene fluoride-hexafluoropropylene.
  • the electrochemical device also includes an electrolyte, and the electrolyte includes a lithium salt and a non-aqueous solvent.
  • the lithium salt may include at least one of LiPF 6 , LiBF 4 , LiClO 4 , LiB(C 6 H 5 ) 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(SO 2 CF 3 ) 2 , LiC(SO 2 CF 3 ) 3 , Li 2 SiF 6 , lithium bis(oxalatoborate) (LiBOB) or lithium difluoroborate.
  • LiPF 6 LiBF 4 , LiClO 4 , LiB(C 6 H 5 ) 4
  • LiBOB lithium bis(o
  • the concentration of the lithium salt in the electrolyte is 0.9 mol/L to 1.5 mol/L.
  • the concentration of the lithium salt in the electrolyte may be 0.9 mol/L, 1.0 mol/L, 1.1 mol/L, 1.3 mol/L, 1.5 mol/L or a range consisting of any two of the above values.
  • the present application has no particular restrictions on the non-aqueous solvent, as long as the purpose of the present application can be achieved, for example, it may include but is not limited to at least one of carbonate compounds, carboxylate compounds, ether compounds or other organic solvents.
  • Fluorinated carbonate compounds may include but are not limited to fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate or trifluoromethylethylene carbonate.
  • FEC fluoroethylene carbonate
  • 1,2-difluoroethylene carbonate 1,1-difluoroethylene carbonate
  • 1,1,2-trifluoroethylene carbonate 1,1,2,2-tetrafluoroethylene carbonate
  • 1-fluoro-2-methylethylene carbonate 1-fluoro-1-methylethylene carbonate
  • 1,2-difluoro-1-methylethylene carbonate 1,1,2-trifluoro-2-methylethylene carbonate or trifluoromethylethylene carbonate.
  • carboxylate compounds may include but are not limited to at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone, decalactone, valerolactone or caprolactone.
  • the above-mentioned other organic solvents may include but are not limited to at least one of dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate or trioctyl phosphate.
  • the preparation process of the electrochemical device of the present application is well known to those skilled in the art, and the present application has no particular limitation.
  • it may include but is not limited to the following steps: stacking the positive electrode sheet, the separator and the negative electrode sheet in order, and winding, folding and other operations as needed to obtain an electrode assembly of a winding structure, placing the electrode assembly in a packaging bag, injecting the electrolyte into the packaging bag and sealing it to obtain an electrochemical device; or, stacking the positive electrode sheet, the separator and the negative electrode sheet in order, and then fixing the four corners of the entire stacked structure with tape to obtain an electrode assembly of a stacked structure, placing the electrode assembly in a packaging bag, injecting the electrolyte into the packaging bag and sealing it to obtain an electrochemical device.
  • overcurrent protection elements, guide plates, etc. may also be placed in the packaging bag as needed to prevent the pressure inside the electrochemical device from rising and overcharging and discharging.
  • the present application has no limitation on the packaging bag, and those skilled in the art may select it according to actual needs, as long as the purpose of the present application can be achieved.
  • an aluminum-plastic film packaging bag may be used.
  • the electrical device can be an electrical device known in the prior art.
  • the electrical device can include but is not limited to: a laptop computer, a pen-type computer, a mobile computer, an e-book player, Portable phones, portable fax machines, portable copiers, portable printers, head-mounted stereo headphones, video recorders, LCD televisions, portable cleaners, portable CD players, mini discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, power-assisted bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, electric tools, flashlights, cameras, large household batteries, and lithium-ion capacitors.
  • the positive electrode materials prepared in each embodiment and comparative example were tested using a spectrometer (Jobin Yvon LabRAM HR), the light source was 532 nm, and the test range was 200 cm -1 to 4000 cm -1 .
  • the positive electrode materials prepared in each embodiment and comparative example were tested using a Malvern particle size tester (instrument model: Master Sizer 2000).
  • the particle size at which the volume accumulation reaches 50% is Dv50, starting from the small particle size.
  • the cathode material was tested by X-ray powder diffractometer (XRD, instrument model: Bruker D8ADVANCE), where the target material was Cu K ⁇ , the test voltage was 40KV, the test current was 35mA, the scanning angle range was 10° to 90°, the scanning rate was 0.02°/s, and the strongest diffraction peak intensity was required to be greater than 10,000, in counts.
  • XRD X-ray powder diffractometer
  • the content of Li and metal elements in the positive electrode material was tested using an inductively coupled plasma spectrometer (ICP, instrument model: PE Optima 7000DV).
  • ICP inductively coupled plasma spectrometer
  • Cycle capacity retention rate discharge capacity at the nth cycle / discharge capacity at the third cycle ⁇ 100%.
  • the obtained mixture material containing lithium cobalt oxide positive electrode material is crushed and washed with deionized water for multiple times to remove soluble sodium salt and lithium salt in the mixture until the conductivity of the supernatant is less than 200 ⁇ S/cm.
  • the residual powder is then filtered, dried and sieved to obtain lithium cobalt oxide material.
  • the Dv50 of the lithium cobalt oxide material is 9.3 ⁇ m.
  • the lithium cobalt oxide obtained above was used as the positive electrode active material, conductive carbon black (SP) was used as the conductive agent, and polyvinylidene fluoride (PVDF) was used as the binder, and the mixture was mixed in a mass ratio of 80:10:10, and N-methyl-2-pyrrolidone (NMP) was added as the solvent, and the mixture was stirred evenly under the action of a vacuum mixer to obtain a positive electrode slurry with a solid content of 60wt%.
  • SP conductive carbon black
  • PVDF polyvinylidene fluoride
  • NMP N-methyl-2-pyrrolidone
  • a 12 ⁇ m aluminum foil was used as the positive electrode current collector, and a coating with a thickness of 100 ⁇ m was coated on the current collector aluminum foil, which was first baked in a blast drying oven at 90°C for 4h, and then baked in a vacuum drying oven at 110°C for 24h.
  • the fully dried pole piece was subjected to cold pressing, punching, weighing, and other processes to obtain a disc-shaped positive pole piece with a diameter of 1.4cm.
  • a lithium metal sheet is used as the counter electrode.
  • fluoroethylene carbonate (FEC), ethylene carbonate (EC), and diethyl carbonate (DEC) were mixed at a volume ratio of 1:1:8 to obtain an organic solvent, and then lithium salt LiPF 6 was added to the organic solvent to dissolve and mix evenly to obtain an electrolyte.
  • the concentration of LiPF 6 was 1 mol/L.
  • a porous PE film with a thickness of 7 ⁇ m is used.
  • the positive electrode sheet is assembled into a button cell with a separator, a negative electrode sheet and an electrolyte.
  • Example 1 The only difference compared with Example 1 is the following aspects of the preparation steps of the positive electrode material:
  • the prepared sodium cobalt oxide material, lithium nitrate (LiNO 3 ) and lithium hydroxide (LiOH) were mixed evenly in a molar ratio of 1:4:1 and then loaded into a corundum crucible, reacted at 250° C. for 8 hours, and cooled to obtain a mixture containing a lithium cobalt manganese oxide positive electrode material;
  • the obtained mixture material is crushed and washed with deionized water for multiple times to remove soluble sodium salt and lithium salt in the mixture until the conductivity of the supernatant is less than 200 ⁇ S/cm.
  • the residual powder is then filtered, dried and sieved to obtain a lithium cobalt manganese oxide material having a Dv50 of 10.2 ⁇ m.
  • NiSO 4 ⁇ 6H 2 O is replaced by Y (NO 3 ) 3 , Nb(NO 3 ) 5 , La(NO 3 ) 3 , Fe(NO 3 ) 3 , and Cu(NO 3 ) 2 respectively to adjust the type of Q element as shown in Table 1, and the addition amount of CaCO 3 is changed to adjust the content of Ca element as shown in Table 1.
  • Example 4 The only difference compared with Example 4 is the following aspects of the preparation steps of the positive electrode material: Cr( NO3 ) 3 , TiCl4 , W( NO3 ) 3 , Lu( NO3 ) 3 , Yb( NO3 ) 2 are used to replace MnSO4 ⁇ H2O respectively to adjust the type of Q element as shown in Table 1, and the addition amount of MgO is changed to adjust the content of Mg element as shown in Table 1.
  • Example 4 The only difference compared with Example 4 is the following aspects of the preparation steps of the positive electrode material: 2 wt % NH 4 F is added during the sintering process of mixing sodium carbonate (Na 2 CO 3 ) and magnesium oxide (MgO) with the prepared metal oxide.
  • Example 4 The only difference compared with Example 4 is the following aspects of the preparation steps of the positive electrode material: 5 wt % NH 4 F is added during the sintering process of mixing sodium carbonate (Na 2 CO 3 ) and magnesium oxide (MgO) with the prepared metal oxide.
  • Example 2 The only difference compared with Example 2 is the following aspects of the preparation steps of the positive electrode material: Ca is introduced in the form of Ca(NO 3 ) 2 during the precursor co-precipitation stage.
  • Mg is introduced in the form of Mg(NO 3 ) 2 during the precursor co-precipitation stage.
  • FIG1 shows the Raman spectra of the materials of Examples 1 to 3 and Comparative Examples 1 to 2. Two Raman characteristic peaks can be seen from FIG1 , with peak positions at 490 ⁇ 5 cm -1 and 592 ⁇ 5 cm -1 , respectively.
  • the former represents the bending vibration mode of O-Co-O
  • the latter represents the stretching vibration mode of Co-O.
  • Example 2 and Comparative Example 3 As well as Example 5 and Comparative Example 4 that, under the same M element doping amount, when the M element is introduced in the coprecipitation precursor stage, the obtained material I 2 /I 1 is smaller, and when the M element is introduced in the sodium cobalt oxide sintering stage, the obtained material I 2 /I 1 is larger.
  • M is introduced by co-precipitation in the precursor stage, and tends to be uniformly doped and distributed in the bulk phase of the target material.
  • the M element when introduced in the sodium cobalt oxide sintering stage, the M element is likely to be distributed in a gradient in the target material, and the doping concentration in the surface layer is higher than that in the bulk phase. Therefore, the I2 / I1 ratio is higher, and the actual improvement effect on the material structure stability, especially the surface interface stability, is more significant.
  • the Raman characteristic peak intensity ratio I 2 /I 1 of the material provided by Comparative Example 1 is about 0.7, and the capacity retention rate of the material after 100 cycles of the battery is low, only 67%; with the increase of the amount of Ca doping, the Raman characteristic peak intensity ratio I 2 /I 1 of Examples 1 to 3 is between 1 and 5, and the battery cycle capacity retention rate is significantly improved, greatly increased to 87% to 93%; when the Ca doping amount is further increased to 0.07, the Raman characteristic peak intensity ratio I 2 /I 1 of the material provided by Comparative Example 2 is 5.5, and the battery cycle capacity retention rate begins to decrease, only 62%.
  • the type of metal element Q in lithium cobalt oxide usually also affects the performance of button cells. It can be seen from Examples 7 to 16 that by adjusting the type of metal element Q within the scope of the present application, it is beneficial to obtain a lithium-ion battery with high cycle performance.
  • Example 17 By comparing Examples 17 to 18 with Example 4, it can be seen that when halogen elements are included in lithium cobalt oxide, the cycle stability of the material can be further improved. Compared with Example 4, Examples 17 and 18 were doped with F and Cl, respectively, and when the resulting materials were cycled 100 times, the capacity retention rate was increased from 86% in Example 4 to 94% and 89%, respectively.

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Abstract

本申请提供了一种正极材料、包含该正极材料的电化学装置和用电装置，其中，正极材料包括具有P63mc晶体结构的锂钴氧化物，所述正极材料的拉曼图谱中，在490cm-1±5cm-1范围内的特征峰的峰强为I1，在592cm-1±5cm-1范围内的特征峰的峰强为I2，满足1＜I2/I1＜5。本申请的正极材料能够支撑过渡金属层，从而减少过渡金属层崩塌，提高正极材料在高脱锂态下的结构稳定性，从而提高电化学装置的循环性能。

Description

一种正极材料、包含该正极材料的电化学装置和用电装置 技术领域
本申请涉及电化学技术领域，特别是涉及一种正极材料、包含该正极材料的电化学装置和用电装置。
背景技术
锂离子电池具有比能量大、工作电压高、自放电率低、体积小、重量轻等特点，在消费类电子产品等领域具有广泛的应用。
随着电动汽车和可移动电子设备的高速发展，人们对锂离子电池的能量密度、安全性、循环性能等相关要求越来越高，迫切的需要对锂离子电池中的正极材料进行改进以提高现有锂离子电池的循环性能。
发明内容
本申请的目的在于提供一种正极材料、包含该正极材料的电化学装置和用电装置，以提高电化学装置的循环性能。具体技术方案如下：
本申请的第一方面提供了一种正极材料，其包括具有P63mc晶体结构的锂钴氧化物，所述正极材料的拉曼图谱中，在490cm-1±5cm-1范围内的特征峰的峰强为I1，在592cm-1±5cm-1范围内的特征峰的峰强为I2，满足1＜I2/I1＜5。本申请的正极材料能够支撑过渡金属层，从而减少过渡金属层崩塌，提高正极材料在高脱锂态下的结构稳定性，从而提高电化学装置的循环稳定性。
在本申请的一些实施方案中，1.2≤I2/I1≤4.3。此时，正极材料表现出较好的循环稳定性，从而提高了电化学装置的循环性能。
在本申请的一些实施方案中，锂钴氧化物包含碱土金属元素M，锂钴氧化物的Li位点掺杂有M元素。此时，M元素掺杂进入Li位点可以形成立柱效应，在高脱锂态时，可以支撑过渡金属层，减少过渡金属层崩塌，从而提高高脱锂态下的正极材料的结构稳定性。
在本申请的一些实施方案中，基于锂钴氧化物中除Li、Na、M以外的金属元素的摩尔量，锂钴氧化物中M元素的摩尔百分含量为0.5％至5％。
在本申请的一些实施方案中，M元素包括Ca或Mg中的至少一种。此时，M元素能够保持相对稳定，有效掺杂进入Li位点形成立柱效应，正极材料表现出较好的循环稳定性。
在本申请的一些实施方案中，锂钴氧化物还包含Na元素和金属元素Q；Q元素包括 Al、Zr、Ni、Mn、Y、Nb、La、Fe、Cu、Cr、Ti、W、Lu或Yb中的至少一种；基于锂钴氧化物中除Li、Na、M以外的金属元素的摩尔量，所述锂钴氧化物中Na元素的摩尔百分含量为0.5％至5％，锂钴氧化物中Q元素的摩尔百分含量为2％至10％。
在本申请的一些实施方案中，锂钴氧化物的通式为NaaLibMyCo1-zQzO2±nTn，其中，0＜a≤0.05，0.65≤b≤1.1，0＜y≤0.05，0≤z≤0.1，0≤n≤0.1，M元素为碱土金属元素，Q元素包括Al、Zr、Ni、Mn、Y、Nb、La、Fe、Cu、Cr、Ti、W、Lu或Yb中的至少一种，T元素为卤素元素。此时，正极材料表现出较好的循环稳定性。
在本申请的一些实施方案中，正极材料的Dv50为5μm至25μm。此时，正极材料具有良好的循环性能。
本申请的第二方面提供了一种电化学装置，其包括正极极片，正极极片包括正极活性材料层，其中，正极活性材料层包括前述任一实施方案中的正极材料。本申请提供的正极材料具有良好的循环稳定性，从而本申请提供的电化学装置具有良好的循环性能。
在本申请的一些实施方案中，电化学装置的充电截止电压不低于4.50V。此时，电化学装置具有更高的可逆容量，具有良好的循环性能。
本申请的第三方面提供了一种用电装置，其包括前述任一实施方案中的电化学装置。本申请提供的电化学装置具有良好的循环性能，从而本申请提供的用电装置具有较长的使用寿命。
本申请的有益效果：本申请提供了一种正极材料、包含该正极材料的电化学装置和用电装置，其中，正极材料包括具有P63mc晶体结构的锂钴氧化物，所述正极材料的拉曼图谱中，在490cm-1±5cm-1范围内的特征峰的峰强为I1，在592cm-1±5cm-1范围内的特征峰的峰强为I2，满足1＜I2/I1＜5。本申请的正极材料能够在高脱锂态时，支撑过渡金属层，从而减少过渡金属层崩塌，提高正极材料在高脱锂态下的结构稳定性，从而提高电化学装置的循环性能。
当然，实施本申请的任一产品或方法并不一定需要同时达到以上所述的所有优点。
附图说明
此处所说明的附图用来提供对本申请的进一步理解，构成本申请的一部分，本申请的示意性实施例及其说明用于解释本申请，并不构成对本申请的不当限定。
图1为本申请实施例1至实施例3和对比例1至对比例2的拉曼光谱图。
具体实施方式
为使本申请的目的、技术方案、及优点更加清楚明白，以下参照附图并举实施例，对本申请进一步详细说明。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员所获得的所有其他实施例，都属于本申请保护的范围。
需要说明的是，本申请的具体实施方式中，以锂离子电池作为电化学装置的例子来解释本申请，但是本申请的电化学装置并不仅限于锂离子电池。
本申请的第一方面提供了一种正极材料，其包括具有P63mc晶体结构的锂钴氧化物，正极材料的拉曼图谱中，在490cm-1±5cm-1范围内的特征峰的峰强为I1，在592cm-1±5cm-1范围内的特征峰的峰强为I2，满足1＜I2/I1＜5。在一种实施方案中，1.2≤I2/I1≤4.3。将I2与I1的比值调控在上述范围内，本申请中的正极材料能够支撑在高脱锂态时的过渡金属层，从而减少过渡金属层崩塌，提高正极材料在高脱锂态下的结构稳定性，从而提高锂离子电池的循环稳定性。
其中，本申请中的高脱锂态是指充电截止电压≥4.55V时，正极材料处于一种高脱锂状态，相比初始满放状态材料，此时正极材料的脱锂量一般≥0.7mol。例如，初始满放状态材料组成为Li0.9CoO2，脱锂量为0.7mol时的正极材料组成变为Li0.2CoO2。
在本申请的一些实施方案中，锂钴氧化物包含碱土金属元素M，锂钴氧化物的Li位点掺杂有M元素。M元素掺杂进入Li位点可以形成立柱效应，在高脱锂态时，可以支撑过渡金属层，减少过渡金属层崩塌，提高了高脱锂态下的正极材料的结构稳定性，从而提高锂离子电池的循环性能。
在本申请的一些实施方案中，基于锂钴氧化物中除Li、Na、M以外的金属元素的摩尔量，锂钴氧化物中M元素的摩尔百分含量为0.5％至5％。
在本申请的一些实施方案中，M元素包括Ca或Mg中的至少一种。此时，M元素能够保持相对稳定，有效掺杂进入Li位点形成立柱效应，锂离子电池表现出较好的循环稳定性。
在本申请的一些实施方案中，锂钴氧化物还包含Na元素和金属元素Q；Q元素包括Al、Zr、Ni、Mn、Y、Nb、La、Fe、Cu、Cr、Ti、W、Lu或Yb中的至少一种；基于锂钴氧化物中除Li、Na、M以外的金属元素的摩尔量，所述锂钴氧化物中Na元素的摩尔百分含量为0.5％至5％，锂钴氧化物中Q元素的摩尔百分含量为2％至10％，包含该正极材料 的锂离子电池表现出良好的循环性能。
在本申请的一些实施方案中，锂钴氧化物的通式为NaaLibMyCo1-zQzO2±nTn，其中，0＜a≤0.05，0.65≤b≤1.1，0＜y≤0.05，0≤z≤0.1，0≤n≤0.1，M元素为碱土金属元素，Q元素包括Al、Zr、Ni、Mn、Y、Nb、La、Fe、Cu、Cr、Ti、W、Lu或Yb中的至少一种，T元素为卤素元素，T元素包括F、Cl、Br或I中的至少一种。本申请通过选用具有上述通式的正极材料，锂离子电池表现出较好的循环稳定性。
在本申请的一些实施方案中，正极材料的Dv50为5μm至25μm，通过调控正极材料的Dv50在上述范围内，锂离子电池具有良好的循环性能。
本申请中，Dv50是指正极材料体积分布中50％的颗粒的粒径尺寸。
本申请对于正极材料的制备方法没有特别限制，只要能实现本申请的目的即可，例如，正极材料的制备方法可以包括但不限于以下步骤：
步骤1、将可溶性钴盐和含掺杂元素Q的金属盐按照比例加入到溶剂中，形成均匀的混合溶液，再加入沉淀剂和络合剂，调节pH为5至9，形成均相沉淀，之后将沉淀物进行烧结、破碎和筛分处理等过程，得到金属氧化物材料；
步骤2、将金属氧化物材料、含钠化合物和含掺杂元素M的化合物按比例称量并混合均匀，在750℃至1050℃的温度下保温24h至72h，得到P63mc结构的钠钴氧化物；
步骤3、将P63mc结构的钠钴氧化物作为前驱体材料，与含锂化合物混合均匀后，装入刚玉坩埚，在220℃至280℃的温度下发生固相反应2至8h，冷却后得到含有锂钴氧化物正极材料的混合物；
步骤4、将步骤3中的混合物材料进行破碎处理，用去离子水进行多次洗涤，去除混合物中的可溶性钠盐和锂盐，之后对残余粉末进行抽滤、烘干和筛分等步骤，得到锂钴氧化物正极材料。
在步骤1中，可溶性钴盐和含掺杂元素的金属盐为氯化物、醋酸盐、硫酸盐或硝酸盐中的至少一种。例如，可溶性钴盐包括氯化钴、醋酸钴、硝酸钴、硫酸钴，含掺杂元素的金属盐包括硝酸镍、硝酸锰，硝酸钇；含钠化合物为Na2O、Na2O2、Na2CO3或NaOH中的至少一种，优选为Na2O和Na2CO3；含掺杂元素M的化合物优选为M元素的氯化物和碳酸盐，例如，包括氯化钙、碳酸钙、碳酸镁；本申请对可溶性钴盐和含掺杂元素Q的金属盐的混合比例没有特别限制，只要能实现本申请的目的即可，可以按照设计比例混合。例如，可溶性钴盐和含掺杂元素Q的金属盐按照1:(0.02至0.11)混合；本申请对沉淀剂和 络合剂没有特别限制，只要能实现本申请的目的即可。例如，沉淀剂包括碳酸铵、碳酸氢铵，络合剂包括氨水、氢氧化钠；沉淀剂和络合剂的添加量没有特别限制，只要能实现本申请的目的即可。例如，基于Co的摩尔数，沉淀剂的加入量为1至2.5倍，络合剂的加入量为1至1.5倍。本申请对烧结温度没有特别限制，例如，烧结温度可以为450℃至700℃；本申请可以使用气流粉碎机设备进行破碎处理，使用振动筛设备进行粒径筛分，从而调控金属氧化物材料的粒径。
在步骤2中，本申请对金属氧化物材料、含钠化合物和含掺杂元素M的化合物的混合比例没有特别限制，可以按照设计比例加入。
在步骤3中，本申请对于含锂化合物没有特别限制，只要能通过本申请的目的即可。例如，含锂化合物包括但不限于硫酸锂、碳酸锂、硝酸锂、卤化锂、羧酸锂、方酸锂、醇锂等。
本申请对调控峰强I1和I2的方法没有特别限制，例如，I2通常随Co-O弯曲振动强度增加而增加，I1通常随Co-O伸缩振动强度增加而增加。基于此，可以通过调控烧结工艺和掺杂等来调控Co-O键的弯曲和伸缩振动强度，从而调控I1与I2的比值范围。
本申请的第二方面提供了一种电化学装置，其包括正极极片，正极极片包括正极活性材料层，其中，正极活性材料层包括前述任一实施方案中的正极材料。本申请提供的正极材料具有良好的循环稳定性，从而本申请提供的电化学装置具有良好的循环性能。
在本申请的一些实施方案中，电化学装置的充电截止电压不低于4.50V。此时，电化学装置具有更高的可逆容量，具有良好的循环性能。
本申请的电化学装置包括正极极片、负极极片、隔膜和电解液。正极极片包含正极集流体和正极活性材料层。本申请对正极集流体没有特别限制，只要能够实现本申请目的即可。例如，正极集流体可以包含铝箔、铝合金箔或复合集流体等。在本申请中，对正极集流体和正极活性材料层的厚度没有特别限制，只要能够实现本申请目的即可。例如，正极集流体的厚度为5μm至20μm，优选为6μm至18μm。单面正极活性材料层的厚度为30μm至120μm。在本申请中，正极活性材料层可以设置于正极集流体厚度方向上的一个表面上，也可以设置于正极集流体厚度方向上的两个表面上。任选地，正极活性材料层还可以包括导电剂和粘结剂。本申请对正极活性材料层中的粘结剂的种类没有特别限制，只要能够实现本申请目的即可，例如，粘结剂可以包括但不限于聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙 烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯或聚六氟丙烯中的至少一种。本申请对正极活性材料层中的导电剂的种类没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于导电炭黑(Super P)、碳纳米管(CNTs)、碳纤维、鳞片石墨、科琴黑、石墨烯、金属材料或导电聚合物中的至少一种。上述碳纳米管可以包括但不限于单壁碳纳米管和/或多壁碳纳米管。上述碳纤维可以包括但不限于气相生长碳纤维(VGCF)和/或纳米碳纤维。上述金属材料可以包括但不限于金属粉和/或金属纤维，具体地，金属可以包括但不限于铜、镍、铝或银中的至少一种。上述导电聚合物可以包括但不限于聚亚苯基衍生物、聚苯胺、聚噻吩、聚乙炔或聚吡咯中的至少一种。本申请对正极活性材料层中正极活性材料、导电剂、粘结剂的质量比没有特别限制，本领域技术人员可以根据实际需要选择，只要能够实现本申请目的即可。
本申请对负极极片没有特别限制，只要能够实现本申请目的即可。例如，负极极片包含负极集流体和负极活性材料层。本申请对负极集流体没有特别限制，只要能够实现本申请目的即可。例如，负极集流体可以包含铜箔、铜合金箔、镍箔、不锈钢箔、钛箔、泡沫镍或泡沫铜等。本申请的负极活性材料层包含负极活性材料。本申请对负极活性材料的种类没有特别限制，只要能够实现本申请目的即可。例如，负极活性材料可以包含天然石墨、人造石墨、中间相微碳球(MCMB)、硬碳、软碳、硅、硅-碳复合物、SiOx(0<x<2)、Li-Sn合金、Li-Sn-O合金、Sn、SnO、SnO2、尖晶石结构的钛酸锂Li4Ti5O12、Li-Al合金或金属锂中的至少一种。在本申请中，对负极集流体、负极活性材料层的厚度没有特别限制，只要能够实现本申请目的即可。例如，负极集流体的厚度为6μm至10μm，负极活性材料层的厚度为30μm至130μm。任选地，负极活性材料层还可以包括导电剂、稳定剂、粘结剂中的至少一种。本申请对负极活性材料层中的导电剂、稳定剂和粘结剂的种类没有特别限制，只要能够实现本申请目的即可。本申请对负极活性材料层中负极活性材料、导电剂、稳定剂和粘结剂的质量比没有特别限制，只要能够实现本申请目的即可。
本申请的电化学装置还包括隔膜，本申请对隔膜没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于聚乙烯(PE)、聚丙烯(PP)、聚四氟乙烯为主的聚烯烃(PO)类隔膜、聚酯膜(例如聚对苯二甲酸二乙酯(PET)膜)、纤维素膜、聚酰亚胺膜(PI)、聚酰胺膜(PA)、氨纶、芳纶膜、织造膜、非织造膜(无纺布)、微孔膜、复合膜、隔膜纸、碾压膜或纺丝膜中的至少一种，优选为PP。本申请的隔膜可以具有多孔结构，孔径的尺寸没有特别限制，只要能实现本申请的目的即可，例如，孔径的尺寸可以为0.01μm 至1μm。在本申请中，隔膜的厚度没有特别限制，只要能实现本申请的目的即可，例如厚度可以为5μm至500μm。
例如，隔膜可以包括基材层和表面处理层。基材层可以为具有多孔结构的无纺布、膜或复合膜，基材层的材料可以包括但不限于聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯或聚酰亚胺中的至少一种。任选地，可以使用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。任选地，基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。
无机物层可以包括但不限于无机颗粒和无机物层粘结剂，本申请对无机颗粒没有特别限制，只要能实现本申请的目的即可，例如，可以包括但不限于氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡中的至少一种。本申请对无机物层粘结剂没有特别限制，例如，可以包括但不限于聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯或聚六氟丙烯中的至少一种。聚合物层中包含聚合物，聚合物的材料可以包括但不限于聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚偏氟乙烯或聚偏氟乙烯-六氟丙烯中的至少一种。
在本申请中，电化学装置还包括电解液，电解液包括锂盐和非水溶剂。锂盐可以包括LiPF6、LiBF4、LiClO4、LiB(C6H5)4、LiCH3SO3、LiCF3SO3、LiN(SO2CF3)2、LiC(SO2CF3)3、Li2SiF6、双草酸硼酸锂(LiBOB)或二氟硼酸锂中的至少一种。本申请对锂盐在电解液中的浓度没有特别限制，只要能实现本申请的目的即可。例如，锂盐在电解液中的浓度为0.9mol/L至1.5mol/L，示例性地，锂盐在电解液中的浓度可以为0.9mol/L、1.0mol/L、1.1mol/L、1.3mol/L、1.5mol/L或为上述任意两个数值组成的范围。本申请对非水溶剂没有特别限制，只要能实现本申请的目的即可，例如可以包括但不限于碳酸酯化合物、羧酸酯化合物、醚化合物或其它有机溶剂中的至少一种。上述碳酸酯化合物可以包括但不限于链状碳酸酯化合物、环状碳酸酯化合物或氟代碳酸酯化合物中的至少一种。上述链状碳酸酯化合物可以包括但不限于碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)或碳酸甲乙酯(MEC)中的至少一种。上述环状碳酸酯可以包括但不限于碳酸乙烯酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)或 碳酸乙烯基亚乙酯(VEC)中的至少一种。氟代碳酸酯化合物可以包括但不限于氟代碳酸乙烯酯(FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯或碳酸三氟甲基亚乙酯中的至少一种。上述羧酸酯化合物可以包括但不限于甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、γ-丁内酯、癸内酯、戊内酯或己内酯中的至少一种。上述醚化合物可以包括但不限于二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、1-乙氧基-1-甲氧基乙烷、2-甲基四氢呋喃或四氢呋喃中的至少一种。上述其它有机溶剂可以包括但不限于二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯或磷酸三辛酯中的至少一种。
本申请的电化学装置没有特别限制，其可以包括发生电化学反应的任何装置。在本申请的一种实施方案中，电化学装置可以包括但不限于：锂离子二次电池(锂离子电池)、锂聚合物二次电池或锂离子聚合物二次电池等。一种实施方案中，电极组件的结构包括卷绕型结构或叠片型结构等。
本申请的电化学装置的制备过程为本领域技术人员所熟知的，本申请没有特别的限制，例如，可以包括但不限于以下步骤：将正极极片、隔膜和负极极片按顺序堆叠，并根据需要将其卷绕、折叠等操作得到卷绕结构的电极组件，将电极组件放入包装袋内，将电解液注入包装袋并封口，得到电化学装置；或者，将正极极片、隔膜和负极极片按顺序堆叠，然后用胶带将整个叠片结构的四个角固定好得到叠片结构的电极组件，将电极组件置入包装袋内，将电解液注入包装袋并封口，得到电化学装置。此外，也可以根据需要将防过电流元件、导板等置于包装袋中，从而防止电化学装置内部的压力上升、过充放电。本申请对包装袋没有限制，本领域技术人员可以根据实际需要进行选择，只要能实现本申请的目的即可。例如，可采用铝塑膜包装袋。
本申请的第三方面提供了一种用电装置，其包括前述任一实施方案中的电化学装置。本申请提供的电化学装置具有良好的循环性能，从而本申请提供的用电装置具有较长的使用寿命。
本申请对用电装置没有特别限定，其可以是用于现有技术中公知的用电装置。例如，用电装置可以包括但不限于：笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、 便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池、锂离子电容器。
实施例
以下，举出实施例及对比例来对本申请的实施方式进行更具体地说明。各种的试验及评价按照下述的方法进行。另外，只要无特别说明，“份”、“％”为质量基准。
测试方法和设备：
拉曼测试：
使用光谱仪(Jobin Yvon LabRAM HR)对各实施例和对比例制备得到的正极材料进行测试，光源为532nm，测试范围为200cm-1至4000cm-1。
正极材料粒径测试：
采用马尔文粒度测试仪(仪器型号为Master Sizer 2000)对各实施例和对比例制备得到的正极材料进行测试。在正极活性材料的体积基准的粒度分布中，从小粒径测起，到达体积累积50％的粒径为Dv50。
XRD测试：
采用X射线粉末衍射仪(XRD，仪器型号：Bruker D8ADVANCE)测试正极材料，其中，靶材为Cu Kα，测试电压为40KV，测试电流为35mA，扫描角度范围为10°至90°，扫描速率为0.02°/s，要求最强衍射峰强度大于10000，单位为counts。通过Fullprof软件对采集到的XRD谱图进行精修，确定物相结构以及掺杂元素占位。
正极材料元素组成测试：
采用电感耦合等离子光谱测试仪(ICP，仪器型号：PE Optima 7000DV)测试正极材料中Li和金属元素含量。首先称取适量的粉末样品，加入10mL左右王水，在185℃左右的平板加热仪环境下保持加热30min至50min，使样品充分消解，然后上机测试。
循环性能测试：
将扣式电池在25℃的环境下陈化24h后，将制得的扣式电池在3V至4.6V的电压范围内进行充放电测试，前2圈按照0.1C充放电倍率进行活化，后续按照0.5C充放电倍率循环测试，其中，以第3圈电池容量为基准来计算电池容量保持率，1C＝273mA/g。
循环容量保持率＝第n次循环的放电容量/第3次循环的放电容量×100％。
实施例1
<正极材料的制备>
分别称取原料七水合硫酸钴(CoSO4·7H2O)13.35kg、六水合硫酸镍(NiSO4·6H2O)0.66kg，加入去离子水快速搅拌溶解，之后加入碳酸铵和氨水调节溶液pH至8，待反应完全后形成均相碳酸盐沉淀物，将沉淀物于650℃的环境下烧结12h，经破碎和筛分处理，得到金属氧化物(Co0.95Ni0.05)3O4；
将碳酸钠(Na2CO3)、碳酸钙(CaCO3)与制得的金属氧化物按照金属元素摩尔比Na∶Ca∶(Co+Ni)＝0.8∶0.01∶1混合均匀后置于830℃的环境下保温48h，经破碎、筛分处理得到具有P63mmc晶体结构的钠钴氧化物材料；
将制得的钠钴氧化物材料、硝酸锂(LiNO3)和氯化锂(LiCl)按照摩尔比1∶4∶1混合均匀后装入刚玉坩埚，先在235℃的环境下反应4h，之后在250℃的环境下反应4h，冷却后得到含有锂钴氧化物正极材料的混合物；
将制得的含有锂钴氧化物正极材料的混合物材料进行破碎处理，用去离子水多次洗涤，去除混合物中的可溶性钠盐和锂盐，直至上清液电导率小于200μS/cm，接着对残余粉末进行抽滤、烘干和筛分，得到锂钴氧化物材料，锂钴氧化物材料的Dv50为9.3μm。
<正极极片的制备>
将上述所得锂钴氧化物作为正极活性材料，以导电碳黑(SP)作为导电剂、聚偏氟乙烯(PVDF)作为粘接剂，按照质量比80∶10∶10进行混合，加入N-甲基-2-吡咯烷酮(NMP)作为溶剂，在真空搅拌机作用下搅拌均匀，获得固含量为60wt％的正极浆料。采用12μm的铝箔作为正极集流体，在集流体铝箔上涂覆100μm厚度的涂层，先在90℃的鼓风干燥箱中烘烤4h，后在110℃的真空干燥箱烘烤24h，将充分干燥后的极片，进行冷压、冲切、称重等过程，得到直径为1.4cm的圆片形正极极片。
<负极极片的制备>
采用锂金属片作为对极片。
<电解液的制备>
在干燥的氩气气氛手套箱中，将氟代碳酸乙烯酯(FEC)、碳酸乙烯酯(EC)、碳酸二乙酯(DEC)按照体积比为1∶1∶8进行混合得到有机溶剂，然后向有机溶剂中加入锂盐LiPF6溶解并混合均匀，得到电解液。其中，LiPF6浓度为1mol/L。
<隔膜的制备>
采用厚度为7μm的多孔PE薄膜。
<锂离子电池的制备>
在干燥氩气气氛下，用上述正极极片，与隔膜、负极极片和电解液组装成扣式电池。
实施例2
与实施例1相比的区别仅在于正极材料的制备步骤的以下方面：Na2CO3、CaCO3与制得的金属氧化物的金属元素摩尔比Na∶Ca∶(Co+Ni)＝0.8∶0.03∶1。
实施例3
与实施例1相比的区别仅在于正极材料的制备步骤的以下方面：Na2CO3、CaCO3与制得的金属氧化物的金属元素摩尔比Na∶Ca∶(Co+Ni)＝0.8∶0.05∶1。
实施例4
与实施例1相比的区别仅在于正极材料的制备步骤的以下方面：
分别称取原料七水合硫酸钴(CoSO4·7H2O)13.49kg、一水合硫酸锰(MnSO4·H2O)原料0.34kg，加入去离子水快速搅拌溶解，之后加入碳酸铵调节溶液pH至8，待反应完全后形成均相碳酸盐沉淀物，将沉淀物于650℃的环境下烧结12h，经破碎和筛分处理，得到金属氧化物(Co0.96Mn0.04)3O4；
将碳酸钠(Na2CO3)、氧化镁(MgO)与制得的金属氧化物按照金属元素摩尔比Na∶Mg∶(Co+Mn)＝0.8∶0.01∶1混合均匀后置于850℃的环境下保温48h，经破碎、筛分处理得到具有P63mmc晶体结构的钠钴锰氧化物材料；
将制得的钠钴氧化物材料、硝酸锂(LiNO3)和氢氧化锂(LiOH)按照摩尔比1∶4∶1混合均匀后装入刚玉坩埚，在250℃的环境下反应8h，冷却后得到含有锂钴锰氧化物正极材料的混合物；
将制得的混合物材料进行破碎处理，用去离子水多次洗涤，去除混合物中的可溶性钠盐和锂盐，直至上清液电导率小于200μS/cm，接着对残余粉末进行抽滤、烘干和筛分，得到锂钴锰氧化物材料，锂钴锰氧化物材料的Dv50为10.2μm。
实施例5
与实施例4相比的区别仅在于正极材料的制备步骤的以下方面：Na2CO3、MgO与制得的金属氧化物的金属元素摩尔比Na∶Mg∶(Co+Mn)＝0.8∶0.03∶1。
实施例6
与实施例4相比的区别仅在于正极材料的制备步骤的以下方面：Na2CO3、MgO与制得的金属氧化物的金属元素摩尔比Na∶Mg∶(Co+Mn)＝0.8∶0.05∶1。
实施例7至实施例11
与实施例1相比的区别仅在于正极材料的制备步骤的以下方面：分别用Y(NO3)3、Nb(NO3)5、La(NO3)3、Fe(NO3)3、Cu(NO3)2替代NiSO4·6H2O从而如表1所示调整Q元素的种类，以及改变CaCO3的添加量从而如表1调整Ca元素的含量。
实施例12至实施例16
与实施例4相比的区别仅在于正极材料的制备步骤的以下方面：分别用Cr(NO3)3、TiCl4、W(NO3)3、Lu(NO3)3、Yb(NO3)2替代MnSO4·H2O从而如表1所示调整Q元素的种类，以及改变MgO的添加量从而如表1调整Mg元素的含量。
实施例17
与实施例4相比的区别仅在于正极材料的制备步骤的以下方面：碳酸钠(Na2CO3)、氧化镁(MgO)与制得的金属氧化物混合烧结的过程中加入2wt％NH4F。
实施例18
与实施例4相比的区别仅在于正极材料的制备步骤的以下方面：碳酸钠(Na2CO3)、氧化镁(MgO)与制得的金属氧化物混合烧结的过程中加入5wt％NH4F。
对比例1
与实施例1相比的区别仅在于正极材料的制备步骤的以下方面：不添加CaCO3，且Na2CO3与制得的金属氧化物的金属元素摩尔比Na∶(Co+Ni)＝0.8∶1。
对比例2
与实施例1相比的区别仅在于正极材料的制备步骤的以下方面：Na2CO3、CaCO3与制得的金属氧化物的金属元素摩尔比Na∶Ca∶(Co+Ni)＝0.8∶0.07∶1。
对比例3
与实施例2相比的区别仅在于正极材料的制备步骤的以下方面：Ca以Ca(NO3)2的形式在前驱共沉淀阶段引入。
对比例4
与实施例5相比的区别仅在于正极材料的制备步骤的以下方面：Mg以Mg(NO3)2的形式在前驱共沉淀阶段引入。
各实施例和对比例的制备参数和性能参数如表1所示。
参见表1，从实施例1至实施例18和对比例1至对比例4可以看出，扣式电池循环100圈后的容量保持率得到明显提高，表明通过调控正极材料峰强为I1与峰强为I2的关系在本申请范围内，有利于提高锂离子电池的循环性能。
图1示出了实施例1至实施例3和对比例1至对比例2材料的拉曼光谱，从图1中可以看到两个拉曼特征峰，峰位分别位于490±5cm-1和592±5cm-1，前者代表O-Co-O的弯曲振动模式，后者代表Co-O的伸缩振动模式。
从实施例1至实施例3与对比例1至对比例2可以看出，M元素的相对含量越高，峰强比I2/I1越大，且I2/I1在本申请范围内时，扣式电池表现出优异的循环性能。表明通过调控正极材料峰强为I1与峰强为I2的关系在本申请范围内，有利于提高锂离子电池的循环性能。从实施例2和对比例3，以及实施例5和对比例4可以看出，在相同M元素掺杂量的情况下，当M元素在共沉淀前驱体阶段引入时，所得材料I2/I1偏小，而M元素在钠钴氧化物烧结阶段引入时，所得材料I2/I1偏大。对此，可能的解释为，前驱体阶段以共沉淀的方式引入M，M在目标材料中倾向于体相均匀掺杂分布，而在钠钴氧化物烧结阶段引入时，则M元素则有可能在目标材料中呈梯度分布，表层的掺杂浓度高于体相，故I2/I1的比值偏高，对材料结构稳定性，特别是表层界面稳定性的实际改善效果也更加显著。
从实施例1至实施例3和对比例1至对比例2还可以看出，在Ni相对含量为0.05mol时，随着Ca掺杂进入Li位含量的增加，材料的拉曼特征峰强比I2/I1呈现增加的趋势，对应电池循环100圈的容量保持率则呈现出先增加后减小的变化趋势。当未经Ca掺杂时，对比例1提供材料的拉曼特征峰强比I2/I1约为0.7，此时材料的电池循环100圈后的容量保持率较低，仅为67％；随着Ca掺杂量的增加，实施例1至实施例3的拉曼特征峰强比I2/I1介于1至5之间，同时电池循环容量保持率明显改善，大幅提升到87％至93％；当Ca掺杂量进一步提升至0.07时，对比例2提供材料的拉曼特征峰强比I2/I1为5.5，此时电池循环容量保持率开始出现降低，仅为62％。对实施例1至实施例3材料循环100圈后的满充态正极极片进行ICP测试，测得Ca的含量与粉末初始态的相同，表明Ca在充放电过程中不会发生脱嵌反应。推测Ca掺杂改善的主要原因是，Ca在Li位形成支柱效应，稳定结构。但是由于Ca2+和Li+半径相差较大，过多的掺杂，将会破坏整体晶体结构的平衡，反而恶化结构稳定性。通过比较实施例1至3和对比例1至2可知，Ca2+的优选掺杂浓度不应高于5％(摩尔百分含量)。
参见表1，锂钴氧化物中金属元素Q的种类通常也会对扣式电池的性能产生影响，从 实施例7至实施例16可以看出，通过调控金属元素Q的种类在本申请范围内，有利于得到具有高循环性能的锂离子电池。
对比实施例17至实施例18和实施例4可以看出，当锂钴氧化物中包含卤素元素时，能够进一步改善材料的循环稳定性。与实施例4相比，实施例17和实施例18分别进行了F和Cl掺杂，所得材料循环100圈时，容量保持率由实施例4的86％分别提升至94％和89％。
以上所述仅为本申请的较佳实施例，并不用以限制本申请，凡在本申请的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本申请保护的范围之内。

Claims (10)

  1. 一种正极材料，其特征在于：包括具有P63mc晶体结构的锂钴氧化物，
    所述正极材料的拉曼图谱中，在490cm-1±5cm-1范围内的特征峰的峰强为I1，在592cm-1±5cm-1范围内的特征峰的峰强为I2，满足：1<I2/I1<5。
  2. 根据权利要求1所述的正极材料，其特征在于：1.2≤I2/I1≤4.3。
  3. 根据权利要求1所述的正极材料，其特征在于：所述锂钴氧化物包含碱土金属元素M；满足如下至少一者：
    (1)所述锂钴氧化物的Li位点掺杂有所述M元素；
    (2)基于所述锂钴氧化物中除Li、Na、M以外的金属元素的摩尔量，所述锂钴氧化物中M元素的摩尔百分含量为0.5％至5％。
  4. 根据权利要求3所述的正极材料，其特征在于：所述M元素包括Ca或Mg中的至少一种。
  5. 根据权利要求3所述的正极材料，其特征在于：
    所述锂钴氧化物还包含Na元素和金属元素Q；
    所述Q元素包括Al、Zr、Ni、Mn、Y、Nb、La、Fe、Cu、Cr、Ti、W、Lu或Yb中的至少一种；
    基于所述锂钴氧化物中除Li、Na、M以外的金属元素的摩尔量，所述锂钴氧化物中Na元素的摩尔百分含量为0.5％至5％，所述锂钴氧化物中Q元素的摩尔百分含量为2％至10％。
  6. 根据权利要求1所述的正极材料，其特征在于：
    所述锂钴氧化物的通式为NaaLibMyCo1-zQzO2±nTn，
    其中，0＜a≤0.05，0.65≤b≤1.1，0＜y≤0.05，0≤z≤0.1，0≤n≤0.1，
    所述M元素为碱土金属元素，所述Q元素包括Al、Zr、Ni、Mn、Y、Nb、La、Fe、Cu、Cr、Ti、W、Lu或Yb中的至少一种，所述T元素为卤素元素。
  7. 根据权利要求1所述的正极材料，其特征在于：所述正极材料的Dv50为5μm至25μm。
  8. 一种电化学装置，其特征在于：包括正极极片，所述正极极片包括正极活性材料层，其中，所述正极活性材料层包括权利要求1-7任一项所述的正极材料。
  9. 根据权利要求8所述的电化学装置，其特征在于：所述电化学装置的充电截止电压 不低于4.50V。
  10. 一种用电装置，包括根据权利要求8或9所述的电化学装置。
PCT/CN2023/085543 2023-03-31 2023-03-31 一种正极材料、包含该正极材料的电化学装置和用电装置 Ceased WO2024197831A1 (zh)

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