WO2024000452A1 - 正极活性材料、电化学装置和用电装置 - Google Patents

正极活性材料、电化学装置和用电装置 Download PDF

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WO2024000452A1
WO2024000452A1 PCT/CN2022/102947 CN2022102947W WO2024000452A1 WO 2024000452 A1 WO2024000452 A1 WO 2024000452A1 CN 2022102947 W CN2022102947 W CN 2022102947W WO 2024000452 A1 WO2024000452 A1 WO 2024000452A1
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active material
lithium
cathode active
diffraction peak
range
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PCT/CN2022/102947
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English (en)
French (fr)
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袁国霞
郎野
徐磊敏
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宁德新能源科技有限公司
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Priority to CN202280021896.4A priority Critical patent/CN117043974A/zh
Priority to PCT/CN2022/102947 priority patent/WO2024000452A1/zh
Publication of WO2024000452A1 publication Critical patent/WO2024000452A1/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
    • 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
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • 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 battery technology, specifically to a positive active material, an electrochemical device and an electrical device.
  • this application provides a cathode active material, an electrochemical device, and an electrical device to solve the problems existing in the prior art to a certain extent.
  • the application provides a cathode active material
  • the cathode active material includes lithium manganese oxide
  • the X-ray diffraction pattern of the cathode active material has a first diffraction peak in the range of 14.3° to 16.3°, And it has a second diffraction peak in the range of 17.3° to 19.3°.
  • the first diffraction peak is the (010) characteristic peak of the o-phase (cubic phase) in lithium manganese oxide
  • the second diffraction peak is the (001) characteristic peak of the m-phase (monoclinic phase) in lithium manganese oxide.
  • the X-ray diffraction pattern of the cathode active material has a third diffraction peak in the range of 45.7° to 47.7°.
  • the third diffraction peak corresponds to the (111) crystal plane of the m-phase in lithium manganese oxide. The existence of this crystal plane can stabilize the crystal structure of the m-phase, thereby improving the first Coulombic efficiency of lithium manganese oxide.
  • the peak intensity of the first diffraction peak is I A and the peak intensity of the second diffraction peak is I B , satisfying: 0.05 ⁇ IA / IB ⁇ 20 .
  • 0.05 ⁇ IA / IB ⁇ 0.9 , or 6 ⁇ IA / IB ⁇ 20 there is a large difference in the content of m-phase and o-phase in lithium manganese oxide, which can cooperate to form a solid solution and promote the removal of Li ions from lithium manganese oxide, thereby further improving the charge specific capacity of lithium manganese oxide.
  • the half-peak width of the first diffraction peak is WA
  • the half-peak width of the second diffraction peak is WB , satisfying: 0.3 ⁇ WA / WB ⁇ 3 .
  • the half-peak widths of the o-phase and m-phase in the lithium manganese oxide are both narrower and the structural stability is higher, thereby further inhibiting the dissolution of Mn in the lithium manganese oxide and improving the service life of the electrochemical device.
  • the peak intensity of the second diffraction peak is I B
  • the peak intensity of the third diffraction peak is I C
  • I B and I C satisfy: 0.08 ⁇ I C /I B ⁇ 0.35.
  • the peak intensity of the third diffraction peak is stronger and the m-phase has fewer crystal defects, which can improve the first Coulombic efficiency of the cathode active material.
  • the lithium manganese oxide includes M elements, including Cr, Al, Mg, Ti, Y, Nb, W, Ga, Zr, V, Sr, Mo, Ru, Ag, Sn, Au , at least one of La, Ce, Pr, Nd, Sm, Gd, Cu, Na, Zn, Fe, Co, Ni or Ca, the molar ratio of M element to Mn element in the lithium manganese oxide is 0.001: 1 to 0.1:1.
  • the presence of M element in lithium manganese oxide can promote the formation of monoclinic phase, thereby improving the structural stability of lithium manganese oxide, inhibiting the dissolution of Mn, and thereby improving the service life of the electrochemical device.
  • the average particle size Dv50 of the cathode active material is 2 ⁇ m to 35 ⁇ m.
  • the lithium manganese oxide has a lamellar structure.
  • the lamellar structure is conducive to the extraction of Li ions from lithium manganese oxide, thereby improving the charge specific capacity of lithium manganese oxide.
  • the molar ratio of Li element to Mn element in the cathode active material is 0.9 to 1.15.
  • the lithium manganese oxide includes Li x Mny M z O 2 , where 0.9 ⁇ x ⁇ 1.15, 0.9 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 0.1, and M includes Cr, Al, Mg, Ti, Y, Nb, W, Ga, Zr, V, Sr, Mo, Ru, Ag, Sn, Au, La, Ce, Pr, Nd, Sm, Gd, Cu, Na, Zn, Fe, Co, Ni or At least one of Ca.
  • the positive active material and lithium metal are assembled into a button battery, and the voltage capacity differential dQ/dV curve of the button battery in the first cycle of charging is between 3.5V-3.7V and 3.85V-4.05V. There is a characteristic peak in the range, and the voltage capacity differential dQ/dV curve of the first discharge cycle of the button battery has a characteristic peak in the range of 3.8V-4.0V.
  • 3.5V-3.7V corresponds to the o-phase charging capacity
  • 3.85V-4.05V corresponds to the m-phase charging capacity
  • the voltage capacity differential dQ/dV curve of the button battery in the first cycle of charging is between 3.5V-3.7V and There are characteristic peaks in the range of 3.85V-4.05V, indicating that there are two phases in lithium manganese oxide, and the two synergistically increase the charge specific capacity of lithium manganese oxide.
  • the voltage capacity differential dQ/dV curve of the button battery in the first cycle of discharge has a characteristic peak in the range of 3.8V-4.0V, indicating that a uniform phase will be formed when Li ions in lithium manganese oxide are back-intercalated, thus improving the stability of the material.
  • the present application provides a method for preparing a cathode active material, which includes: mixing a manganese-containing oxide, a lithium source and an optional M element source to obtain a mixture; and calcining under a first temperature condition to obtain the cathode active material; wherein the manganese-containing oxide and the lithium source are mixed according to a lithium-manganese molar ratio Li/Mn in the range of 0.90-1.15; the first The atmosphere conditions are inert atmosphere.
  • the inert atmosphere includes at least one of nitrogen, argon, or helium.
  • the first temperature is 880°C-1100°C.
  • the calcination time ranges from 5 hours to 20 hours.
  • the manganese-containing oxide includes Mn 3 O 4 .
  • the M element includes Cr, Al, Mg, Ti, Y, Nb, W, Ga, Zr, V, Sr, Mo, Ru, Ag, Sn, Au, La, Ce, Pr, Nd , at least one of Sm, Gd, Cu, Na, Zn, Fe, Co, Ni or Ca.
  • the M element source includes at least one of CrO 2 , Al 2 O 3 , MgO, TiO 2 or Y 2 O 3 .
  • the manganese-containing oxide and the M element source are mixed according to a molar ratio of the M element to the Mn element M:Mn in the range of 0.001:1 to 0.1:1.
  • the lithium source includes at least one of lithium hydroxide, lithium carbonate, lithium acetate, lithium nitrate, or lithium sulfate.
  • the present application provides an electrochemical device, which includes the positive active material according to the first aspect of the present application or the positive active material prepared according to the second aspect of the present application.
  • the present application provides an electrical device, which includes the electrochemical device according to the third aspect of the present application.
  • the present application provides a cathode active material, which contains lithium manganese oxide.
  • the cathode active material Through the coexistence of o-phase (cubic phase) and m-phase (monoclinic phase) in the lithium manganese oxide, the cathode active material has While having a higher charge specific capacity, it also has good structural stability, which can reduce the amount of Mn dissolution of the electrochemical device in the charged state, thereby improving the service life of the electrochemical device.
  • FIG. 1 shows the XRD pattern of the cathode active material in Example 1.
  • Figure 2 shows the first cycle charge and discharge curve of the button battery in Example 1.
  • FIG. 3 shows the voltage capacity differential dQ/dV curve of the button battery in the first cycle of charge and discharge in Example 1.
  • a list of items connected by the term "at least one of,” “at least one of,” “at least one of,” or other similar terms may mean that the listed items any combination of.
  • the phrase “at least one of A and B” means only A; only B; or A and B.
  • the phrase “at least one of A, B, and C” means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B and C.
  • Item A may contain a single component or multiple components.
  • Item B may contain a single component or multiple components.
  • Item C may contain a single component or multiple components.
  • the present application provides an electrochemical device including a positive electrode, a negative electrode and an electrolyte.
  • the positive electrode includes a positive electrode current collector and a positive electrode material layer located on at least one surface of the positive electrode current collector, the positive electrode material layer includes a positive electrode active material, the positive electrode active material includes lithium manganese oxide , the X-ray diffraction pattern of the cathode active material has a first diffraction peak in the range of 14.3° to 16.3°. In some embodiments, the X-ray diffraction pattern of the cathode active material has a first diffraction peak in the range of 14.5° to 16°. In some embodiments, the X-ray diffraction pattern of the cathode active material has a first diffraction peak in the range of 14.8° to 15.8°. In some embodiments, the X-ray diffraction pattern of the cathode active material has a first diffraction peak in a range of 15° to 15.6°.
  • the X-ray diffraction pattern of the cathode active material has a second diffraction peak in the range of 17.3° to 19.3°. In some embodiments, the X-ray diffraction pattern of the cathode active material has a second diffraction peak in the range of 17.5° to 19°. In some embodiments, the X-ray diffraction pattern of the cathode active material has a second diffraction peak in the range of 17.8° to 18.8°. In some embodiments, the X-ray diffraction pattern of the cathode active material has a second diffraction peak in the range of 18° to 18.5°.
  • the first diffraction peak is the (010) characteristic peak of the o-phase (cubic phase) in lithium manganese oxide
  • the second diffraction peak is the (001) characteristic peak of the m-phase (monoclinic phase) in lithium manganese oxide.
  • the X-ray diffraction pattern of the cathode active material has a third diffraction peak in the range of 45.7° to 47.7°. In some embodiments, the X-ray diffraction pattern of the cathode active material has a third diffraction peak in the range of 46° to 47.5°. In some embodiments, the X-ray diffraction pattern of the cathode active material has a third diffraction peak in the range of 46.4° to 47°. Among them, the third diffraction peak corresponds to the (111) crystal plane of the m-phase in lithium manganese oxide. The existence of this crystal plane can stabilize the crystal structure of the m-phase, thereby improving the first Coulombic efficiency of lithium manganese oxide.
  • the peak intensity of the first diffraction peak is I A and the peak intensity of the second diffraction peak is I B , satisfying: 0.05 ⁇ IA / IB ⁇ 20 .
  • the value of I A /I B is 0.05, 0.08, 0.09, 0.15, 0.05, 0.06, 0.08, 0.09, 0.1, 0.15, 0.5, 0.8, 13, 1.5, 2, 3, 5, 8, A range of 9, 10, 12, 14, 16, 18, 20, or any two of these values.
  • 0.05 ⁇ IA / IB ⁇ 0.9 , or 6 ⁇ IA / IB ⁇ 20 there is a large difference in the content of m-phase and o-phase in lithium manganese oxide, which can cooperate to form a solid solution and promote the removal of Li ions from lithium manganese oxide, thereby further improving the charge specific capacity of lithium manganese oxide.
  • the half-peak width of the first diffraction peak is WA
  • the half-peak width of the second diffraction peak is WB , satisfying: 0.3 ⁇ WA / WB ⁇ 3 .
  • the value of WA / WB is a range of 0.3, 0.5, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2.0, 2.5, 2.8, 3, or any two of these values.
  • the half-peak widths of the o-phase and m-phase in the lithium manganese oxide are both narrower and the structural stability is higher, thereby further inhibiting the dissolution of Mn in the lithium manganese oxide and improving the service life of the electrochemical device.
  • the peak intensity of the second diffraction peak is I B
  • the peak intensity of the third diffraction peak is I C , satisfying: 0.08 ⁇ I C /I B ⁇ 0.35.
  • the value of I C / IB is a range of 0.08, 0.1, 0.13, 0.15, 0.18, 0.2, 0.25, 0.28, 0.3, 0.32, 0.35, or any two of these values.
  • the peak intensity of the third diffraction peak is stronger and the m-phase has fewer crystal defects, which can improve the first Coulomb efficiency of the cathode active material.
  • the lithium manganese oxide includes M elements, including Cr, Al, Mg, Ti, Y, Nb, W, Ga, Zr, V, Sr, Mo, Ru, Ag, Sn, Au , at least one of La, Ce, Pr, Nd, Sm, Gd, Cu, Na, Zn, Fe, Co, Ni or Ca, the molar ratio of M element to Mn element in the lithium manganese oxide is 0.001: 1 to 0.1:1. In some embodiments, the molar ratio of the M element to the Mn element is 0.001:1, 0.005:1, 0.012:1, 0.015:1, 0.02:1, 0.03:1, 0.06:1, 0.1:1 or among these values. A range consisting of any two. The presence of M element in lithium manganese oxide can promote the formation of monoclinic phase, thereby improving the structural stability of lithium manganese oxide, inhibiting the dissolution of Mn, and thereby improving the service life of the electrochemical device.
  • M elements including Cr, Al, Mg, Ti,
  • the average particle size Dv50 of the cathode active material is 2 ⁇ m to 35 ⁇ m. In some embodiments, the average particle size Dv50 of the positive active material is 2 ⁇ m, 4 ⁇ m, 6 ⁇ m, 8 ⁇ m, 10 ⁇ m, 12 ⁇ m, 14 ⁇ m, 16 ⁇ m, 18 ⁇ m, 20 ⁇ m, 24 ⁇ m, 26 ⁇ m, 28 ⁇ m, 30 ⁇ m, 32 ⁇ m, 35 ⁇ m or these. A range consisting of any two values.
  • the lithium manganese oxide has a lamellar structure.
  • the lamellar structure is conducive to the extraction of Li ions from lithium manganese oxide, thereby improving the charge specific capacity of the electrochemical device.
  • the molar ratio of Li element to Mn element in the cathode active material is 0.9 to 1.15.
  • the lithium manganese oxide includes Li x Mny M z O 2 , where 0.9 ⁇ x ⁇ 1.15, 0.9 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 0.1, and M includes Cr, Al, Mg, Ti, Y, Nb, W, Ga, Zr, V, Sr, Mo, Ru, Ag, Sn, Au, La, Ce, Pr, Nd, Sm, Gd, Cu, Na, Zn, Fe, Co, Ni or At least one of Ca.
  • the positive active material and lithium metal are assembled into a button battery, and the voltage capacity differential dQ/dV curve of the button battery in the first cycle of charging is between 3.5V-3.7V and 3.85V-4.05V.
  • the voltage capacity differential dQ/dV curve of the button battery in the first cycle of charging is between 3.5V-3.7V and 3.85V-4.05V.
  • 3.5V-3.7V corresponds to the o-phase charging capacity
  • 3.85V-4.05V corresponds to the m-phase charging capacity
  • the voltage capacity differential dQ/dV curve of the button battery in the first cycle of charging is between 3.5V-3.7V
  • There are characteristic peaks in the range of 3.85V-4.05V indicating that there are two phases in lithium manganese oxide. The two phases work synergistically to increase the charge specific capacity of lithium manganese oxide.
  • the voltage capacity differential dQ/dV curve of the button cell during the first discharge cycle has a characteristic peak in the range of 3.8V-4.0V.
  • the voltage capacity differential dQ/dV curve of the button battery in the first cycle of discharge has a characteristic peak in the range of 3.8V-4.0V, indicating that a uniform phase will be formed when Li ions in lithium manganese oxide are back-intercalated, thus improving the stability of the material.
  • the present application provides a method for preparing a cathode active material, which method includes:
  • the manganese-containing oxide, the lithium source and the optional M element source are mixed to obtain a mixture; the obtained mixture is calcined under the first atmosphere condition and the first temperature condition to obtain the positive electrode active material.
  • the first atmosphere condition is an inert atmosphere.
  • the inert atmosphere includes at least one of nitrogen, argon, or helium.
  • the first temperature is 880°C-1100°C.
  • the first temperature is a range of 880°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, or any two of these values.
  • the calcination time ranges from 5 hours to 20 hours. In some embodiments, the time of the first heat treatment is a range of 5 hours, 7 hours, 9 hours, 10 hours, 12 hours, 15 hours, 18 hours, 20 hours, or any two of these values.
  • the manganese-containing oxide and the lithium source are mixed according to a lithium-manganese molar ratio in the range of 0.90-1.15.
  • the lithium to manganese molar ratio is a range of 0.90, 0.92, 0.95, 0.98, 1, 1.05, 1.1, 1.15, or any two of these values.
  • the manganese-containing oxide includes Mn 3 O 4 .
  • the M element includes Cr, Al, Mg, Ti, Y, Nb, W, Ga, Zr, V, Sr, Mo, Ru, Ag, Sn, Au, La, Ce, Pr, Nd, Sm , at least one of Gd, Cu, Na, Zn, Fe, Co, Ni or Ca.
  • the M element source includes at least one of CrO 2 , Al 2 O 3 , MgO, TiO 2 or Y 2 O 3 .
  • the manganese-containing oxide and the M element source are mixed according to a molar ratio of M element to Mn element M:Mn ranging from 0.001:1 to 0.1:1.
  • the molar ratio M:Mn of the M element to the Mn element is 0.001:1, 0.005:1, 0.012:1, 0.015:1, 0.02:1, 0.03:1, 0.06:1, 0.1:1 or A range consisting of any two of these values.
  • the lithium source is selected from at least one of: lithium hydroxide, lithium carbonate, lithium acetate, lithium nitrate, or lithium sulfate.
  • the cathode material layer includes a conductive agent.
  • the conductive agent includes at least one of graphite, conductive carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.
  • the content of the conductive agent is 0.5% to 20% based on the total mass of the cathode material layer. In some embodiments, based on the total mass of the cathode material layer, the content of the conductive agent is 0.5%, 1%, 5%, 8%, 10%, 12%, 14%, 16%, 18%, 20% or any two of these values.
  • the cathode material layer includes a binder.
  • the binder includes styrene-butadiene rubber (SBR), water-based acrylic resin, carboxymethylcellulose (CMC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), At least one of vinyl butyral (PVB), ethylene-vinyl acetate copolymer (EVA) or polyvinyl alcohol (PVA).
  • the content of the binder is 0.1 to 5% based on the total mass of the cathode material layer. In some embodiments, based on the total mass of the cathode material layer, the content of the binder is 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2% , 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or a range consisting of any two of these values.
  • the positive current collector includes a metal foil or a porous metal plate. In some embodiments, the positive current collector includes a foil or porous plate of metals such as aluminum, copper, nickel, titanium, or silver, or alloys thereof. In some embodiments, the positive current collector is aluminum foil.
  • the thickness of the positive electrode current collector is 5 ⁇ m to 20 ⁇ m. In some embodiments, the thickness of the positive electrode current collector is in a range of 5 ⁇ m, 8 ⁇ m, 10 ⁇ m, 12 ⁇ m, 15 ⁇ m, 18 ⁇ m, 20 ⁇ m, or any two of these values.
  • the positive electrode can be obtained by the following method: mixing a positive electrode active material, a conductive agent and a binder in a solvent to prepare a positive electrode slurry, and coating the positive electrode slurry on the positive electrode current collector, After drying and cold pressing, the positive electrode is obtained.
  • the solvent may include N-methylpyrrolidone and the like, but is not limited thereto.
  • the electrolyte solution that can be used in the embodiments of the present application may be an electrolyte solution known in the art.
  • the electrolyte includes an organic solvent, a lithium salt, and additives.
  • the organic solvent of the electrolyte solution according to the present application may be any organic solvent known in the prior art that can be used as a solvent for the electrolyte solution.
  • the lithium salt used in the electrolyte solution according to the present application is not limited, and it can be any lithium salt known in the prior art.
  • the additives of the electrolyte according to the present application may be any additives known in the art that can be used as electrolyte additives.
  • the organic solvent includes, but is not limited to, one or more of the following: cyclic carbonate, chain carbonate, cyclic carboxylate, chain carboxylate, cyclic ether , chain ethers, phosphorus-containing organic solvents, sulfur-containing organic solvents and aromatic fluorine-containing solvents.
  • the organic solvent includes ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), carbonic acid Dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), At least one of ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) or diethyl sulfone
  • EB
  • the lithium salt includes at least one of an organic lithium salt or an inorganic lithium salt.
  • the lithium salt includes, but is not limited to: lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium difluorophosphate (LiPO 2 F 2 ), bistrifluoromethanesulfonimide Lithium LiN(CF 3 SO 2 ) 2 (LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO 2 F) 2 )(LiFSI), lithium bisoxalatoborate LiB(C 2 O 4 ) 2 (LiBOB ) or lithium difluoroborate borate LiBF 2 (C 2 O 4 ) (LiDFOB).
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium tetrafluoroborate
  • LiPO 2 F 2 lithium difluorophosphate
  • LiTFSI bistrifluoromethanesulfonimide Lithium LiN(CF 3 SO 2 ) 2
  • the concentration of lithium salt in the electrolyte is 0.5 mol/L-3 mol/L. In some embodiments, the concentration of lithium salt in the electrolyte is 0.8 mol/L-1.5 mol/L.
  • the negative electrode includes a negative electrode current collector and a negative electrode material layer located on one or both surfaces of the negative electrode current collector.
  • the negative electrode material layer contains a negative electrode active material.
  • the negative electrode material layer may be one or more layers, and each layer of the multiple negative electrode material layers may contain the same or different negative electrode active materials.
  • the negative active material is any material that can reversibly intercalate and deintercalate lithium ions.
  • examples of negative electrode current collectors include, but are not limited to, foils or porous plates of metal materials such as copper, aluminum, nickel, stainless steel, nickel-plated steel, etc. In some embodiments, the negative electrode current collector is copper foil.
  • the thickness of the negative electrode current collector is 1 ⁇ m to 50 ⁇ m.
  • the negative active material is not particularly limited as long as it can reversibly absorb and release lithium ions.
  • Examples of negative active materials may include, but are not limited to, carbon materials such as graphite and hard carbon; silicon materials such as silicon (Si), silicon-oxygen materials, and silicon-carbon materials.
  • the negative active materials can be used alone or in combination.
  • the negative electrode material layer may further include a negative electrode binder.
  • the negative electrode binder can improve the binding between the negative electrode active material particles and the binding between the negative electrode active material and the current collector.
  • the type of negative electrode binder is not particularly limited as long as it is a material that is stable to the electrolyte or the solvent used in electrode production.
  • the negative electrode binder includes a resin binder. Examples of resin binders include, but are not limited to, fluororesin, polyacrylonitrile (PAN), polyimide resin, acrylic resin, polyolefin resin, and the like.
  • the negative electrode binder includes, but is not limited to, carboxymethylcellulose (CMC) or its salt, styrene-butadiene rubber (SBR), polyacrylic acid (PAA) or its salt, polyethylene Alcohol etc.
  • CMC carboxymethylcellulose
  • SBR styrene-butadiene rubber
  • PAA polyacrylic acid
  • the negative electrode can be prepared by the following method: coating a negative electrode slurry containing a negative electrode active material, a negative electrode binder, etc. on the negative electrode current collector, drying and then cold pressing, thereby obtaining the negative electrode.
  • an isolation film is usually provided between the positive electrode and the negative electrode.
  • the material of the isolation membrane can be resin, glass fiber, inorganic substances, etc. that are stable to the electrolyte of the present application.
  • the isolation film includes a porous sheet or non-woven fabric-like material with excellent liquid retention properties.
  • resin materials may include, but are not limited to, polyolefin, aromatic polyamide, polytetrafluoroethylene, polyethersulfone, and the like.
  • the polyolefin is polyethylene or polypropylene.
  • the polyolefin is polypropylene.
  • the isolation film may also be a material formed by laminating the above materials. Examples thereof include, but are not limited to, a three-layer isolation film formed by laminating polypropylene, polyethylene, and polypropylene in this order.
  • inorganic materials may include, but are not limited to, alumina, silica, boehmite, aluminum nitride, silicon nitride, sulfates (eg, barium sulfate, calcium sulfate, etc.).
  • the form of the inorganic matter may include, but is not limited to, granular, plate or fiber.
  • the thickness of the isolation film is arbitrary. In some embodiments, the thickness of the isolation film is greater than 1 ⁇ m, greater than 5 ⁇ m, or greater than 8 ⁇ m. In some embodiments, the thickness of the isolation film is less than 50 ⁇ m, less than 40 ⁇ m, or less than 30 ⁇ m. In some embodiments, the thickness of the isolation film is within a range consisting of any two of the above values. When the thickness of the isolation film is within the above range, insulation and mechanical strength can be ensured, and rate characteristics and energy density of the electrochemical device can be ensured.
  • the porosity of the isolation membrane is arbitrary. In some embodiments, the isolation membrane has a porosity greater than 10%, greater than 15%, or greater than 20%. In some embodiments, the isolation membrane has a porosity of less than 60%, less than 50%, or less than 45%. In some embodiments, the porosity of the isolation film is within a range consisting of any two of the above values. When the porosity of the isolation film is within the above range, insulation and mechanical strength can be ensured, and membrane resistance can be suppressed, allowing the electrochemical device to have good rate characteristics.
  • the electrochemical device of the present application includes any device in which an electrochemical reaction occurs, and specific examples thereof include all kinds of primary batteries or secondary batteries.
  • the electrochemical device is a lithium secondary battery, including a lithium metal secondary battery or a lithium ion secondary battery.
  • the present application further provides an electrical device, which includes the electrochemical device according to the present application.
  • the use of the electrochemical device of the present application is not particularly limited, and it can be used in any electrical device known in the art.
  • the electrochemical device of the present application can be used in, but is not limited to, notebook computers, pen-input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, headsets, etc.
  • step (2) Mix the anhydrous Mn 3 O 4 and LiOH obtained in step (1) at a molar ratio of Li:Mn of 1.05:1, and then add the M element source at a molar ratio of M element:Mn of 0.03:1. , use a mixing device to mix for 8 hours to obtain a mixture, in which the M element is Al and the M element source is nanometer Al 2 O 3 ; and
  • the positive electrode active material binder polyvinylidene fluoride (PVDF), and conductive carbon black in a mass ratio of 90:5:5, add N-methylpyrrolidone (NMP), and stir evenly under the action of a vacuum mixer to obtain a positive electrode slurry.
  • ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) evenly at a volume ratio of 1:1:1 to obtain an organic solvent.
  • LiPF 6 is dissolved in the above-mentioned organic solvent to obtain an electrolyte solution, in which the concentration of LiPF 6 in the electrolyte solution is 1 mol/L.
  • the obtained positive electrode, polypropylene separator and metal lithium sheet are placed in the button battery steel case in order, an appropriate amount of electrolyte is dropped, and after sealing, a lithium ion button battery is obtained.
  • the Dv50 of the LiMnO 2 cathode active material obtained in Example 1 is 17 ⁇ m; its X-ray diffraction pattern (XRD) is shown in Figure 1, and the first cycle charge and discharge curve of the lithium ion button battery is shown in Figure 2.
  • the first cycle charge and discharge curve The voltage capacity differential dQ/dV curve is shown in Figure 3.
  • Example 17-22 The difference between the preparation methods of the cathode active materials of Examples 2-22 and Example 1 lies in the parameters in Table 1.
  • the Cr element source is CrO 2
  • the Ti element source is TiO 2
  • the Mg element source is MgO
  • the Y element source is Y 2 O 3 .
  • Two or more M elements are present in Examples 17-22. Take Example 17 as an example.
  • the M element type is Al+Cr
  • M/Mn is 0.02:1+0.01:1, which means that the M elements in the example are Al and Cr, and the moles of Al, Cr and Mn The ratios are 0.02:1 and 0.01:1 respectively.
  • Examples 18-22 can be deduced in this way.
  • Mn 2 O 3 and Na 2 CO 3 are mixed evenly according to the Na:Mn molar ratio of 1.05:1, and then in an N 2 atmosphere, the temperature is raised to 800°C at a heating rate of 5°C/min and maintained at a constant temperature for 24 hours to obtain NaMnO 2 ; add LiBr ethanol solution with a concentration of 5 mol/L according to the LiBr: NaMnO 2 molar ratio of 10:1, exchange it for 8 hours at 180°C in an air atmosphere, wash with ethanol after completion, and place the powder at 120°C after washing Dry in the oven for 5 hours to obtain lithium manganese oxide using the traditional method.
  • the positive active material powder was placed in the sample stage of the XRD testing instrument (model Bruker, D8), using a scanning rate of 2°/min and a scanning angle range of 10° to 90° to obtain an X-ray diffraction pattern. Read the position, intensity and half-peak width of each peak.
  • Dv50 refers to the particle size that reaches 50% of the cumulative volume from the small particle size side in the volume-based particle size distribution.
  • a mixed solvent to dissolve the cathode active material for example, 0.4g of cathode active material uses a mixed solvent of 10ml (nitric acid and hydrochloric acid mixed at 1:1) aqua regia and 2ml HF), adjust the volume to 100mL, and then use an ICP analyzer to test, and obtain The content of elements such as M element, Mn element and Li element in the positive electrode active material.
  • the LAND series battery test system was used to conduct charge and discharge tests on lithium-ion button batteries to test their charge and discharge performance. They were charged at a constant current of 0.1C at 45°C until the voltage reached 4.3V, and further charged at a constant voltage of 4.3V. Charge until the current is 0.05C, making it in a full charge state of 4.3V. The obtained charging specific capacity is recorded as the first charging specific capacity. Then discharge at a constant current at a rate of 0.1C until the voltage reaches 3V. The obtained discharge specific capacity is the first discharge specific capacity. The ratio of the first discharge specific capacity to the first charge specific capacity is recorded as the 45°C first efficiency.
  • the lithium-ion button battery Charge the lithium-ion button battery to 4V at a constant current rate of 0.1C. After disassembly, take the positive electrode and soak it in the 60°C electrolyte for 7 days. Use ICP to test the Mn element content in the electrolyte.
  • the Mn dissolution amount Mn element content in the electrolyte/mass of positive electrode active material.
  • Tables 1 and 2 show the preparation parameters and related properties of the cathode active materials in Examples 1 to 22 and Comparative Examples 1 and 2.
  • I A is the peak intensity of the first diffraction peak
  • I B is the peak intensity of the second diffraction peak
  • W A is the half-peak width of the first diffraction peak
  • W B is the half-peak width of the second diffraction peak
  • I C is The third diffraction peak is strong.
  • Example 1 0.08 1.21 0.14 245 42.9% 1567
  • Example 2 0.09 1.45 0.15 240 45.3% 2054
  • Example 3 0.13 2.36 0.18 218 53.1% 2576
  • Example 4 0.87 1.89 0.2 197 48.7% 2708
  • Example 5 0.08 1.63 0.14 235 46.8% 2365
  • Example 6 1.32 0.65 0.22 181 45.2% 2906
  • Example 7 0.08 1.29 0.14 241 43.5% 1876
  • Example 8 0.10 1.35 0.15 203 44.2% 1965
  • Example 9 0.05 1.52 0.08 249 45.5% 1098
  • Example 10 0.06 1.36 0.11 246 43.6% 1276
  • Example 11 1.04 0.56 0.2 185 45.9% 2907
  • Example 12 6.23 0.69 0.22 191 44.8% 2706
  • Example 13 9.32 0.76 0.26 192 44.7% 2465
  • Example 14 15.76 0.79 0.3 201 44.2% 2387
  • Example 15 19.97 0.83 0.35 210 44.1% 2208
  • button batteries can have a higher charge specific capacity is that there is a large difference in the content of m-phase and o-phase in lithium manganese oxide, which can synergistically form a solid solution and promote Li ions in lithium manganese oxide. of lithium manganese oxide, thus further improving the charge specific capacity of lithium manganese oxide. It can be seen from the comparison between Examples 1-2, 5-10 and 13-22 and other Examples that when 0.75 ⁇ W A /W B ⁇ 1.65 is satisfied, the amount of Mn dissolution is further reduced. The possible reason is that at this time , the half-peak widths of the o-phase and m-phase in lithium manganese oxide are both narrower and the structural stability is higher, thereby further inhibiting the dissolution of Mn in lithium manganese oxide.

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Abstract

本申请公开了一种正极活性材料、电化学装置和用电装置。本申请的正极活性材料包含锂锰氧化物，所述正极活性材料的X射线衍射图谱在14.3°至16.3°范围内具有第一衍射峰，且在17.3°至19.3°范围内具有第二衍射峰。本申请的正极活性材料充电比容量高，且结构稳定性好，能够提升电化学装置的能量密度和使用寿命。

Description

正极活性材料、电化学装置和用电装置 技术领域
本申请涉及电池技术领域，具体涉及一种正极活性材料、电化学装置和用电装置。
背景技术
为了解决全球能源危机、环境污染、气候变化、低碳经济等严峻问题，电动交通工具、大型动力电源及储能领域电源的研发和应用成为必然。尖晶石LiMn 2O 4及橄榄石型LiFePO 4因成本低、首效高、安全可靠性好，作为正极活性材料被广泛使用。然而，因尖晶石LiMn 2O 4及橄榄石型LiFePO 4充电容量低，且负极需要消耗活性Li形成固态电解质界面膜(SEI膜)，同时为了保证安全，负极活性物质通常过剩，从而造成LiMn 2O 4或LiFePO 4在电池里的容量发挥偏低。同时，随着循环过程中，SEI膜的破坏和再生，活性Li被进一步消耗，从而导致尖晶石LiMn 2O 4及橄榄石型LiFePO 4在电池充电状态下的结构稳定性降低，恶化电池的使用寿命。
发明内容
鉴于现有技术存在的上述问题，本申请通过提供一种正极活性材料、电化学装置和用电装置，以在某种程度上解决存在于现有技术的问题。
在第一方面，本申请提供了一种正极活性材料，所述正极活性材料包含锂锰氧化物，所述正极活性材料的X射线衍射图谱在14.3°至16.3°范围内具有第一衍射峰，且在17.3°至19.3°范围内具有第二衍射峰。其中，第一衍射峰为锂锰氧化物中o-相(立方相)的(010)特征峰，第二衍射峰为锂锰氧化物中m-相(单斜相)的(001)特征峰，通过锂锰氧化物中o-相和m-相的共存，形成固溶体，提升了锂锰氧化物在电化学装置充电状态下的结构稳定性；两相共存形成的固溶体存在氧空位，能够促进锂离子的脱出，从而能够提升锂锰氧化物的充电比容量；同时，通过固溶体协同效应，能够增加Mn-O键的稳定性，从而能够抑制锂锰氧化物中的Mn溶出，进而改善电化学装置的使用寿命。
在一些实施例中，所述正极活性材料的X射线衍射图谱在45.7°至47.7°范围内具有第三衍射峰。其中，第三衍射峰对应锂锰氧化物中m-相的(111)晶面，该晶面的存在能 够稳定m-相的晶体结构，从而提升锂锰氧化物的首次库伦效率。
在一些实施例中，所述第一衍射峰的峰强为I A，所述第二衍射峰的峰强为I B，满足：0.05≤I A/I B≤20。
在一些实施例中，0.05≤I A/I B≤0.9，或6≤I A/I B≤20。此时，锂锰氧化物中m-相与o-相的含量存在较大差异，能够协同作用形成固溶体，促进锂锰氧化物中Li离子的脱出，从而进一步提升锂锰氧化物的充电比容量。
在一些实施例中，所述第一衍射峰的半峰宽为W A，第二衍射峰的半峰宽为W B，满足：0.3≤W A/W B≤3。
在一些实施例中，0.75≤W A/W B≤1.65。此时，锂锰氧化物中的o-相和m-相的半峰宽均较窄，结构稳定性更高，从而进一步抑制锂锰氧化物中的Mn溶出，改善电化学装置的使用寿命。
在一些实施例中，所述第二衍射峰的峰强为I B，所述第三衍射峰的峰强为I C，I B和I C满足：0.08≤I C/I B≤0.35。此时，第三衍射峰的峰强较强，m-相的晶体缺陷较少，能够提高正极活性材料的首次库伦效率。
在一些实施例中，所述锂锰氧化物包含M元素，M元素包括Cr、Al、Mg、Ti、Y、Nb、W、Ga、Zr、V、Sr、Mo、Ru、Ag、Sn、Au、La、Ce、Pr、Nd、Sm、Gd、Cu、Na、Zn、Fe、Co、Ni或Ca中的至少一种，所述锂锰氧化物中M元素与Mn元素的摩尔比为0.001∶1至0.1∶1。锂锰氧化物中M元素的存在，能够促进单斜相的形成，从而提升锂锰氧化物的结构稳定性，抑制Mn的溶出，进而改善电化学装置的使用寿命。
在一些实施例中，所述正极活性材料的平均粒径Dv50为2μm至35μm。
在一些实施例中，所述锂锰氧化物具有片层状结构。片层状结构有利于锂锰氧化物中Li离子的脱出，从而提升锂锰氧化物的充电比容量。
在一些实施例中，所述正极活性材料中Li元素与Mn元素的摩尔比为0.9至1.15。
在一些实施例中，所述锂锰氧化物包括Li xMn yM zO 2，其中，0.9≤x≤1.15，0.9≤y≤1，0≤z≤0.1，M包括Cr、Al、Mg、Ti、Y、Nb、W、Ga、Zr、V、Sr、Mo、Ru、Ag、Sn、Au、La、Ce、Pr、Nd、Sm、Gd、Cu、Na、Zn、Fe、Co、Ni或Ca中的至少一种。在一些实施方式中，0.9≤x≤1.2，0.9≤y≤1，0.001≤z≤0.1。
在一些实施例中，将所述正极活性材料与锂金属组装成扣式电池，所述扣式电池的首圈充电的电压容量微分dQ/dV曲线在3.5V-3.7V和3.85V-4.05V范围内具有特征峰，所述扣式电池的首圈放电的电压容量微分dQ/dV曲线在3.8V-4.0V范围内具有特征峰。其中，3.5V-3.7V对应o-相的充电容量，3.85V-4.05V对应m-相的充电容量；扣式电池 的首圈充电的电压容量微分dQ/dV曲线在3.5V-3.7V和3.85V-4.05V范围内具有特征峰，表明锂锰氧化物中具有两相，两者协同作用提升锂锰氧化物的充电比容量。扣式电池的首圈放电的电压容量微分dQ/dV曲线在3.8V-4.0V范围内具有特征峰，表明锂锰氧化物中Li离子回嵌时会形成均一相，从而提升材料的稳定性。
在第二方面，本申请提供一种正极活性材料的制备方法，其包括：将含锰氧化物、锂源和可选的M元素源，进行混合得到混合物；将所述混合物在第一气氛条件以及第一温度条件下进行煅烧，得到所述正极活性材料；其中，所述含锰氧化物和所述锂源按照锂锰摩尔比Li/Mn为0.90-1.15的范围进行混合；所述第一气氛条件为惰性气氛。
在一些实施例中，所述惰性气氛包括氮气、氩气或氦气中的至少一种。
在一些实施例中，所述第一温度为880℃-1100℃。
在一些实施例中，所述煅烧的时间为5小时至20小时。
在一些实施例中，所述含锰氧化物包括Mn 3O 4。
在一些实施例中，所述M元素包括Cr、Al、Mg、Ti、Y、Nb、W、Ga、Zr、V、Sr、Mo、Ru、Ag、Sn、Au、La、Ce、Pr、Nd、Sm、Gd、Cu、Na、Zn、Fe、Co、Ni或Ca中的至少一种。
在一些实施例中，所述M元素源包括CrO 2、Al 2O 3、MgO、TiO 2或Y 2O 3中的至少一种。
在一些实施例中，所述含锰氧化物和所述M元素源按照所述M元素与Mn元素的摩尔比M∶Mn为0.001∶1至0.1∶1的范围进行混合。
在一些实施例中，所述锂源包括氢氧化锂、碳酸锂、乙酸锂、硝酸锂或硫酸锂中的至少一种。
在第三方面，本申请提供一种电化学装置，其包括根据本申请的第一方面所述的正极活性材料或根据本申请的第二方面所制备的正极活性材料。
在第四方面，本申请提供一种用电装置，其包括根据本申请的第三方面所述的电化学装置。
本申请提供了一种正极活性材料，该正极活性材料包含锂锰氧化物，通过锂锰氧化物中o-相(立方相)与m-相(单斜相)共存，该正极活性材料在具有较高的充电比容量的同时，具有较好的结构稳定性，能够降低电化学装置在充电状态下的Mn溶出量，进而改善电化学 装置的使用寿命。
本申请的额外层面及优点将部分地在后续说明中描述和显示，或是经由本申请实施例的实施而阐释。
附图说明
图1示出了实施例1中的正极活性材料的XRD图谱。
图2示出了实施例1中的扣式电池的首圈充放电曲线。
图3示出了实施例1中的扣式电池的首圈充放电的电压容量微分dQ/dV曲线。
具体实施方式
本申请的实施例将会被详细的描示在下文中。本申请的实施例不应该被解释为对本申请的限制。
另外，有时在本文中以范围格式呈现量、比率和其它数值。应理解，此类范围格式是用于便利及简洁起见，且应灵活地理解，不仅包含明确地指定为范围限制的数值，而且包含涵盖于所述范围内的所有个别数值或子范围，如同明确地指定每一数值及子范围一般。
在具体实施方式及权利要求书中，由术语“中的至少一者”、“中的至少一个”、“中的至少一种”或其他相似术语所连接的项目的列表可意味着所列项目的任何组合。例如，如果列出项目A及B，那么短语“A及B中的至少一者”意味着仅A；仅B；或A及B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的至少一者”意味着仅A；或仅B；仅C；A及B(排除C)；A及C(排除B)；B及C(排除A)；或A、B及C的全部。项目A可包含单个元件或多个元件。项目B可包含单个元件或多个元件。项目C可包含单个元件或多个元件。
一、电化学装置
在一些实施例中，本申请提供了一种电化学装置，所述电化学装置包括正极、负极和电解液。
1、正极
在一些实施例中，所述正极包含正极集流体和位于所述正极集流体的至少一个表面上的正极材料层，所述正极材料层包括正极活性材料，所述正极活性材料包含锂锰氧化物，所述 正极活性材料的X射线衍射图谱在14.3°至16.3°范围内具有第一衍射峰。在一些实施例中，所述正极活性材料的X射线衍射图谱在14.5°至16°范围内具有第一衍射峰。在一些实施例中，所述正极活性材料的X射线衍射图谱在14.8°至15.8°范围内具有第一衍射峰。在一些实施例中，所述正极活性材料的X射线衍射图谱在15°至15.6°范围内具有第一衍射峰。
在一些实施例中，所述正极活性材料的X射线衍射图谱在17.3°至19.3°范围内具有第二衍射峰。在一些实施例中，所述正极活性材料的X射线衍射图谱在17.5°至19°范围内具有第二衍射峰。在一些实施例中，所述正极活性材料的X射线衍射图谱在17.8°至18.8°范围内具有第二衍射峰。在一些实施例中，所述正极活性材料的X射线衍射图谱在18°至18.5°范围内具有第二衍射峰。
其中，第一衍射峰为锂锰氧化物中o-相(立方相)的(010)特征峰，第二衍射峰为锂锰氧化物中m-相(单斜相)的(001)特征峰，通过锂锰氧化物中o-相和m-相的共存，形成固溶体，提升了锂锰氧化物在电化学装置充电状态下的结构稳定性；两相共存形成的固溶体存在氧空位，能够促进锂离子的脱出，从而能够提升锂锰氧化物的充电比容量；同时，通过固溶体协同效应，能够增加Mn-O键的稳定性，从而能够抑制锂锰氧化物中的Mn溶出，进而改善电化学装置的使用寿命。
在一些实施例中，所述正极活性材料的X射线衍射图谱在45.7°至47.7°范围内具有第三衍射峰。在一些实施例中，所述正极活性材料的X射线衍射图谱在46°至47.5°范围内具有第三衍射峰。在一些实施例中，所述正极活性材料的X射线衍射图谱在46.4°至47°范围内具有第三衍射峰。其中，第三衍射峰对应锂锰氧化物中m-相的(111)晶面，该晶面的存在能够稳定m-相的晶体结构，从而提升锂锰氧化物的首次库伦效率。
在一些实施例中，所述第一衍射峰的峰强为I A，所述第二衍射峰的峰强为I B，满足：0.05≤I A/I B≤20。在一些实施例中，I A/I B的值为0.05、0.08、0.09、0.15、0.05、0.06、0.08、0.09、0.1、0.15、0.5、0.8、13、1.5、2、3、5、8、9、10、12、14、16、18、20或这些数值中任意两者组成的范围。
在一些实施例中，0.05≤I A/I B≤0.9，或6≤I A/I B≤20。此时，锂锰氧化物中m-相与o-相的含量存在较大差异，能够协同作用形成固溶体，促进锂锰氧化物中Li离子的脱出，从而进一步提升锂锰氧化物的充电比容量。
在一些实施例中，所述第一衍射峰的半峰宽为W A，第二衍射峰的半峰宽为W B，满足：0.3≤W A/W B≤3。在一些实施例中，W A/W B的值为0.3、0.5、0.6、0.8、1、1.2、1.4、1.6、1.8、 2.0、2.5、2.8、3或这些数值中任意两者组成的范围。
在一些实施例中，0.75≤W A/W B≤1.65。此时，锂锰氧化物中的o-相和m-相的半峰宽均较窄，结构稳定性更高，从而进一步抑制锂锰氧化物中的Mn溶出，改善电化学装置的使用寿命。
在一些实施例中，所述第二衍射峰的峰强为I B，所述第三衍射峰的峰强为I C，满足：0.08≤I C/I B≤0.35。在一些实施例中，I C/I B的值为0.08、0.1、0.13、0.15、0.18、0.2、0.25、0.28、0.3、0.32、0.35或这些数值中任意两者组成的范围。第三衍射峰的峰强较强，m-相的晶体缺陷较少，能够提高正极活性材料的首次库伦效率。
在一些实施例中，所述锂锰氧化物包含M元素，M元素包括Cr、Al、Mg、Ti、Y、Nb、W、Ga、Zr、V、Sr、Mo、Ru、Ag、Sn、Au、La、Ce、Pr、Nd、Sm、Gd、Cu、Na、Zn、Fe、Co、Ni或Ca中的至少一种，所述锂锰氧化物中M元素与Mn元素的摩尔比为0.001∶1至0.1∶1。在一些实施例中，M元素与Mn元素的摩尔比为0.001∶1、0.005∶1、0.012∶1、0.015∶1、0.02∶1、0.03∶1、0.06∶1、0.1∶1或这些数值中任意两者组成的范围。锂锰氧化物中M元素的存在，能够促进单斜相的形成，从而提升锂锰氧化物的结构稳定性，抑制Mn的溶出，进而改善电化学装置的使用寿命。
在一些实施例中，所述正极活性材料的平均粒径Dv50为2μm至35μm。在一些实施例中，所述正极活性材料的平均粒径Dv50为2μm、4μm、6μm、8μm、10μm、12μm、14μm、16μm、18μm、20μm、24μm、26μm、28μm、30μm、32μm、35μm或这些数值中任意两者组成的范围。
在一些实施例中，所述锂锰氧化物具有片层状结构。片层状结构有利于锂锰氧化物中Li离子的脱出，从而提升电化学装置的充电比容量。
在一些实施例中，所述正极活性材料中Li元素与Mn元素的摩尔比为0.9至1.15。
在一些实施例中，所述锂锰氧化物包括Li xMn yM zO 2，其中，0.9≤x≤1.15，0.9≤y≤1，0≤z≤0.1，M包括Cr、Al、Mg、Ti、Y、Nb、W、Ga、Zr、V、Sr、Mo、Ru、Ag、Sn、Au、La、Ce、Pr、Nd、Sm、Gd、Cu、Na、Zn、Fe、Co、Ni或Ca中的至少一种。在一些实施方式中，0.9≤x≤1.2，0.9≤y≤1，0.001≤z≤0.1。
在一些实施例中，将所述正极活性材料与锂金属组装成扣式电池，所述扣式电池的首圈充电的电压容量微分dQ/dV曲线在3.5V-3.7V和3.85V-4.05V范围内具有特征峰。其中，3.5V-3.7V对应o-相的充电容量，3.85V-4.05V对应m-相的充电容量；扣式电池的首圈 充电的电压容量微分dQ/dV曲线在3.5V-3.7V和3.85V-4.05V范围内具有特征峰，表明锂锰氧化物中具有两相，两者协同作用，提升锂锰氧化物的充电比容量。
在一些实施例中，所述扣式电池的首圈放电的电压容量微分dQ/dV曲线在3.8V-4.0V范围内具有特征峰。扣式电池的首圈放电的电压容量微分dQ/dV曲线在3.8V-4.0V范围内具有特征峰，表明锂锰氧化物中Li离子回嵌时会形成均一相，从而提升材料的稳定性。
在一实施例中，本申请提供了正极活性材料的制备方法，所述方法包括：
将含锰氧化物、锂源和可选的M元素源，进行混合得到混合物；将得到的混合物在第一气氛条件以及第一温度条件下进行煅烧，得到所述正极活性材料。
在一些实施例中，所述第一气氛条件为惰性气氛。在一些实施例中，所述惰性气氛包括氮气、氩气或氦气中的至少一种。
在一些实施例中，所述第一温度为880℃-1100℃。
在一些实施例中，所述第一温度为880℃、900℃、950℃、1000℃、1050℃、1100℃或这些数值中任意两者组成的范围。
在一些实施例中，所述煅烧的时间为5小时至20小时。在一些实施例中，所述第一热处理的时间为5小时、7小时、9小时、10小时、12小时、15小时、18小时、20小时或这些数值中任意两者组成的范围。
在一些实施例中，所述含锰氧化物和所述锂源按照锂锰摩尔比为0.90-1.15的范围进行混合。在一些实施例中，锂锰摩尔比为0.90、0.92、0.95、0.98、1、1.05、1.1、1.15或这些数值中任意两者组成的范围。
在一些实施例中，所述含锰氧化物包括Mn 3O 4。
在一些实施例中，M元素包括Cr、Al、Mg、Ti、Y、Nb、W、Ga、Zr、V、Sr、Mo、Ru、Ag、Sn、Au、La、Ce、Pr、Nd、Sm、Gd、Cu、Na、Zn、Fe、Co、Ni或Ca中的至少一种。在一些实施例中，M元素源包括CrO 2、Al 2O 3、MgO、TiO 2或Y 2O 3中的至少一种。
在一些实施例中，所述含锰氧化物和所述M元素源按照M元素与Mn元素的摩尔比M∶Mn为0.001∶1至0.1∶1的范围进行混合。在一些实施例中，M元素与Mn元素的摩尔比M∶Mn为0.001∶1、0.005∶1、0.012∶1、0.015∶1、0.02∶1、0.03∶1、0.06∶1、0.1∶1或这些数值中任意两者组成的范围。
在一些实施例中，所述锂源选自如下中的至少一者：氢氧化锂、碳酸锂、乙酸锂、硝酸锂或硫酸锂。
在一些实施例中，所述正极材料层包括导电剂。在一些实施例中，所述导电剂包括石墨、导电碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯或碳纳米纤维中的至少一者。
在一些实施例中，基于所述正极材料层的总质量，所述导电剂的含量为0.5％至20％。在一些实施例中，基于所述正极材料层的总质量，所述导电剂的含量为0.5％、1％、5％、8％、10％、12％、14％、16％、18％、20％或这些数值中任意两者组成的范围。
在一些实施例中，所述正极材料层包括粘结剂。在一些实施例中，所述粘结剂包括丁苯橡胶(SBR)、水性丙烯酸树脂、羧甲基纤维素(CMC)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚乙烯醇缩丁醛(PVB)、乙烯-醋酸乙烯酯共聚物(EVA)或聚乙烯醇(PVA)中的至少一者。
在一些实施例中，基于所述正极材料层的总质量，所述粘结剂的含量为0.1至5％。在一些实施例中，基于所述正极材料层的总质量，所述粘结剂的含量为0.1％、0.2％、0.5％、0.8％、1％、1.2％、1.5％、1.8％、2％、2.5％、3％、3.5％、4％、4.5％、5％或这些数值中任意两者组成的范围。
在一些实施例中，正极集流体包括金属箔材或多孔金属板。在一些实施例中，正极集流体包括铝、铜、镍、钛或银等金属或它们的合金的箔材或多孔板。在一些实施例中，正极集流体为铝箔。
在一些实施例中，所述正极集流体的厚度为5μm至20μm。在一些实施例中，所述正极集流体的厚度为5μm、8μm、10μm、12μm、15μm、18μm、20μm或这些数值中任意两者组成的范围。
在一些实施例中，所述正极可以通过如下方法获得：将正极活性材料、导电剂和粘合剂在溶剂中混合，以制备正极浆料，将该正极浆料涂覆在正极集流体上，干燥后冷压，获得所述正极。在一些实施例中，所述溶剂可以包括N-甲基吡咯烷酮等，但不限于此。
2、电解液
可用于本申请实施例的电解液可以为现有技术中已知的电解液。
在一些实施例中，所述电解液包括有机溶剂、锂盐和添加剂。根据本申请的电解液的有机溶剂可为现有技术中已知的任何可作为电解液的溶剂的有机溶剂。根据本申请的电解液中 使用的锂盐没有限制，其可为现有技术中已知的任何锂盐。根据本申请的电解液的添加剂可为现有技术中已知的任何可作为电解液添加剂的添加剂。
在一些实施例中，所述有机溶剂包括，但不限于，以下中的一种或多种：环状碳酸酯、链状碳酸酯、环状羧酸酯、链状羧酸酯、环状醚、链状醚、含磷有机溶剂、含硫有机溶剂和芳香族含氟溶剂。
在一些实施例中，所述有机溶剂包括碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸丁烯酯(BC)、氟代碳酸乙烯酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1，4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)或二乙砜(ESE)中的至少一者。
在一些实施例中，所述锂盐包括有机锂盐或无机锂盐中的至少一种。
在一些实施例中，所述锂盐包括，但不限于：六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、二氟磷酸锂(LiPO 2F 2)、双三氟甲烷磺酰亚胺锂LiN(CF 3SO 2) 2(LiTFSI)、双(氟磺酰)亚胺锂Li(N(SO 2F) 2)(LiFSI)、双草酸硼酸锂LiB(C 2O 4) 2(LiBOB)或二氟草酸硼酸锂LiBF 2(C 2O 4)(LiDFOB)。
在一些实施例中，所述电解液中锂盐的浓度为0.5mol/L-3mol/L。在一些实施例中，所述电解液中锂盐的浓度为0.8mol/L-1.5mol/L。
3、负极
在一些实施例中，负极包括负极集流体和位于所述负极集流体的一个或两个表面上的负极材料层。所述负极材料层包含负极活性物质。负极材料层可以是一层或多层，多层负极材料层中的每层可以包含相同或不同的负极活性物质。负极活性物质为任何能够可逆地嵌入和脱嵌锂离子的物质。
在一些实施例中，负极集流体的实例包括，但不限于，铜、铝、镍、不锈钢、镀镍钢等金属材料的箔材或多孔板。在一些实施例中，负极集流体为铜箔。
在一些实施例中，负极集流体的厚度为1μm至50μm。
负极活性物质没有特别限制，只要能够可逆地吸藏、放出锂离子即可。负极活性物质的 实例可包括，但不限于，石墨、硬碳等碳材料；硅(Si)、硅氧材料、硅碳材料等硅材料。负极活性物质可以单独使用或组合使用。
在一些实施例中，负极材料层还可包括负极粘合剂。负极粘合剂可提高负极活性物质颗粒彼此间的结合和负极活性物质与集流体的结合。负极粘合剂的种类没有特别限制，只要是对于电解液或电极制造时使用的溶剂稳定的材料即可。在一些实施例中，负极粘合剂包括树脂粘合剂。树脂粘合剂的实例包括，但不限于，氟树脂、聚丙烯腈(PAN)、聚酰亚胺树脂、丙烯酸系树脂、聚烯烃树脂等。当使用水系溶剂制备负极浆料时，负极粘合剂包括，但不限于，羧甲基纤维素(CMC)或其盐、丁苯橡胶(SBR)、聚丙烯酸(PAA)或其盐、聚乙烯醇等。
在一些实施例中，负极可以通过以下方法制备：在负极集流体上涂布包含负极活性物质、负极粘合剂等的负极浆料，干燥后冷压，由此可以得到负极。
4、隔离膜
在一些实施例中，为了防止短路，在正极与负极之间通常设置有隔离膜。对隔离膜的材料及形状没有特别限制，只要不显著损害本申请的效果即可。所述隔离膜的材料可为对本申请的电解液稳定的树脂、玻璃纤维、无机物等。在一些实施例中，所述隔离膜包括保液性优异的多孔性片或无纺布状形态的物质。树脂材料的实例可包括，但不限于，聚烯烃、芳香族聚酰胺、聚四氟乙烯、聚醚砜等。在一些实施例中，所述聚烯烃为聚乙烯或聚丙烯。在一些实施例中，所述聚烯烃为聚丙烯。上述隔离膜的材料可以单独使用或任意组合使用。
所述隔离膜还可为上述材料层积而成的材料，其实例包括，但不限于，按照聚丙烯、聚乙烯、聚丙烯的顺序层积而成的三层隔离膜等。
无机物材料的实例可包括，但不限于，氧化铝、二氧化硅、勃姆石、氮化铝、氮化硅、硫酸盐(例如，硫酸钡、硫酸钙等)。无机物的形式可包括，但不限于，颗粒状、板状或纤维状。
所述隔离膜的厚度是任意的。在一些实施例中，所述隔离膜的厚度为大于1μm、大于5μm或大于8μm。在一些实施例中，所述隔离膜的厚度为小于50μm、小于40μm或小于30μm。在一些实施例中，所述隔离膜的厚度在上述任意两个数值所组成的范围内。当所述隔离膜的厚度在上述范围内时，则可以确保绝缘性和机械强度，并可以确保电化学装置的倍率特性和能量密度。
所述隔离膜的孔隙率是任意的。在一些实施例中，所述隔离膜的孔隙率为大于10％、大于15％或大于20％。在一些实施例中，所述隔离膜的孔隙率为小于60％、小于50％或小于 45％。在一些实施例中，所述隔离膜的孔隙率在上述任意两个数值所组成的范围内。当所述隔离膜的孔隙率在上述范围内时，可以确保绝缘性和机械强度，并可以抑制膜电阻，使电化学装置具有良好的倍率特性。
5、电化学装置
本申请的电化学装置包括发生电化学反应的任何装置，它的具体实例包括所有种类的一次电池或二次电池。特别地，该电化学装置是锂二次电池，包括锂金属二次电池或锂离子二次电池。
本申请另提供了一种用电装置，其包括根据本申请所述的电化学装置。
本申请的电化学装置的用途没有特别限定，其可用于现有技术中已知的任何用电装置。在一些实施例中，本申请的电化学装置可用于，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、手提式清洁器、便携CD机、收发机、电子记事本、计算器、便携式录音机、收音机、备用电源、电动汽车、电动摩托车、电动自行车、照明器具、玩具、游戏机、钟表、电动工具、照相机、家庭用大型蓄电池和锂离子电容器等。
下面以锂离子扣式电池为例并且结合具体的实施例说明本申请的正极活性材料，本领域的技术人员将理解，本申请中描述的实施例仅是示例，而非对本申请保护范围的限制。
实施例1
1、正极活性材料的制备
(1)将Mn(OOH)放置在坩埚中，在空气气氛下，以5℃/min的升温速率升温至500℃并保持恒温4h，得到无水Mn 3O 4；
(2)将步骤(1)中得到的无水Mn 3O 4与LiOH按照Li∶Mn为1.05∶1的摩尔比进行混合，再按照M元素∶Mn为0.03∶1的摩尔比加入M元素源，使用混合设备混合8h，得到混合物，其中，M元素为Al，M元素源为纳米Al 2O 3；和
(3)将上述混合物放置在刚玉坩埚中，以2m 3/h的速度通入氮气，以5℃/min的升温速率升温至940℃，并在940℃烧结10h，自然冷却至室温，即获得片层状LiMnO 2正极活性材料。
2、正极的制备
将正极活性材料、粘结剂聚偏氟乙烯(PVDF)、导电炭黑按质量比90∶5∶5混合，加入 N-甲基吡咯烷酮(NMP)，在真空搅拌机作用下搅拌均匀，获得正极浆料，其中正极浆料的固含量为72wt％；将正极浆料均匀涂覆在厚度为13μm的正极集流体铝箔的一个表面上，90℃下烘干，冷压后裁取直径为1.4cm的圆片，得到正极。
3、电解液的制备
将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)及碳酸二乙酯(DEC)按照体积比为1∶1∶1混合均匀，得到有机溶剂。将LiPF 6溶解于上述有机溶剂中得到电解液，其中电解液中LiPF 6的浓度为1mol/L。
4、锂离子扣式电池的制备
将得到的正极、聚丙烯隔离膜和金属锂片，按顺序置于扣式电池钢壳中，滴入适量电解液，密封后得到锂离子扣式电池。
实施例1中获得的LiMnO 2正极活性材料的Dv50为17μm；其X射线衍射图谱(XRD)如图1所示，锂离子扣式电池首圈充放电曲线如图2所示，首圈充放电的电压容量微分dQ/dV曲线如图3所示。
实施例2-22与实施例1的正极活性材料的制备方法的区别在于表1中的参数。其中，Cr元素源为CrO 2，Ti元素源为TiO 2，Mg元素源为MgO，Y元素源为Y 2O 3。其中实施例17-22中存在两种或多种M元素。以实施例17举例说明，实施例17中M元素种类为Al+Cr，M/Mn为0.02∶1+0.01∶1，代表实施例中M元素为Al和Cr，且Al和Cr与Mn的摩尔比分别为0.02∶1和0.01∶1。实施例18-22以此类推。
对比例1
传统方法将Mn 2O 3与Na 2CO 3按照Na∶Mn摩尔比为1.05∶1混合均匀后，在N 2气氛中，以5℃/min的升温速率升温至800℃并保持恒温24h，得到NaMnO 2；按照LiBr∶NaMnO 2摩尔比为10∶1加入浓度为5mol/L的LiBr乙醇溶液，在空气气氛下，180℃下交换8h，完成后用乙醇洗涤，洗涤后将粉末置于120℃烘箱中干燥5h，得到传统方法的锂锰氧化物。
对比例2
按照Li∶Mn摩尔比为0.56∶1的比例称取Li 2CO 3、MnO 2，按照Al∶Mn摩尔比为0.03的比例加入Al 2O 3，在高速混合机中以转速300r/min混合20min得到混合物，将混合物置于空气窑炉中，以5℃/min升温至790℃，保持24h，自然冷却后取出，过300目筛后得到尖晶石型锰酸锂。
测试方法
1、XRD测试
将正极活性材料粉末放置在XRD测试仪器(型号布鲁克，D8)样品台中，使用2°/min的扫描速率，扫描角度范围10°至90°，得到X射线衍射图谱。读取各峰的位置、强度以及半峰宽。
2、形貌测试
使用扫描电子显微镜(SEM)对正极活性材料粉末进行测试；选择放大倍数为10000倍
的SEM图像。
3、平均粒径测试
使用粒度分析仪测试正极活性材料的平均粒径Dv50。
Dv50是指在体积基准的粒度分布中，从小粒径侧起、达到体积累积50％的粒径。
4、元素含量测试方法
使用混合溶剂溶解正极活性材料(例如，0.4g正极活性材料使用10ml(硝酸与盐酸按照1∶1混合)王水与2ml HF的混合溶剂)，定容至100mL，然后使用ICP分析仪测试，获得正极活性材料中M元素、Mn元素和Li元素等元素的含量。
5、锂离子扣式电池充放电测试
采用蓝电(LAND)系列电池测试系统对锂离子扣式电池进行充放电测试，测试其充放电性能，在45℃下以0.1C倍率恒定电流充电至电压达到4.3V，进一步在4.3V恒定电压下充电至电流为0.05C，使其处于4.3V满充状态，得到的充电比容量记为第一次充电比容量。随后在0.1C倍率下恒流放电，直到电压为3V，得到的放电比容量为第一次放电比容量，第一次放电比容量与第一次充电比容量的比值记为45℃首次效率。
6、dQ/dV测试
对锂离子扣式电池第一次充放电数据进行微积分，即得到电压容量微分dQ/dV曲线。
7、Mn溶出量的测试
将锂离子扣式电池以0.1C倍率恒定电流充电至4V，拆解后取正极浸泡于60℃电解液中，浸泡时间为7天，利用ICP测试电解液中的Mn元素含量，Mn溶出量＝电解液中的Mn 元素含量/正极活性材料质量。
测试结果
表1和2示出了实施例1至22以及对比例1和2中正极活性材料的制备参数和相关性能。其中I A为第一衍射峰的峰强；I B为第二衍射峰的峰强；W A为第一衍射峰的半峰宽；W B为第二衍射峰的半峰宽；I C为第三衍射峰的峰强。
表1
Figure PCTCN2022102947-appb-000001
其中“/”表示不存在该物质或该性能参数
表2
  I A/I B W A/W B I C/I B 45℃充电比 45℃首次 Mn溶出
      容量/mAh/g 效率 量/ppm
实施例1 0.08 1.21 0.14 245 42.9％ 1567
实施例2 0.09 1.45 0.15 240 45.3％ 2054
实施例3 0.13 2.36 0.18 218 53.1％ 2576
实施例4 0.87 1.89 0.2 197 48.7％ 2708
实施例5 0.08 1.63 0.14 235 46.8％ 2365
实施例6 1.32 0.65 0.22 181 45.2％ 2906
实施例7 0.08 1.29 0.14 241 43.5％ 1876
实施例8 0.10 1.35 0.15 203 44.2％ 1965
实施例9 0.05 1.52 0.08 249 45.5％ 1098
实施例10 0.06 1.36 0.11 246 43.6％ 1276
实施例11 1.04 0.56 0.2 185 45.9％ 2907
实施例12 6.23 0.69 0.22 191 44.8％ 2706
实施例13 9.32 0.76 0.26 192 44.7％ 2465
实施例14 15.76 0.79 0.3 201 44.2％ 2387
实施例15 19.97 0.83 0.35 210 44.1％ 2208
实施例16 0.09 1.24 0.15 239 43.1％ 1687
实施例17 0.08 1.22 0.14 242 43.0％ 1708
实施例18 0.10 1.25 0.15 235 43.2％ 1845
实施例19 0.10 1.26 0.15 236 43.2％ 1902
实施例20 0.09 1.27 0.15 241 43.3％ 1934
实施例21 0.08 1.25 0.14 243 43.2％ 1623
实施例22 0.07 1.19 0.12 247 42.7％ 1423
对比例1 / / 0.38 169 53.1％ 3012
对比例2 / / / 119 95.0％ 3567
其中“/”表示不存在该物质或该性能参数
由实施例1-22与对比例1和2的比较可以看出，当正极活性材料的X射线衍射图谱在14.3°至16.3°范围内具有第一衍射峰，且在17.3°至19.3°范围内具有第二衍射峰时，锂离子扣式电池的充电比容量较高，且Mn的溶出量较小。可能的原因在于，其中，第一衍射峰为锂锰氧化物中o-相(立方相)的(010)特征峰，第二衍射峰为锂锰氧化物中m-相(单斜相)的(001)特征峰，通过锂锰氧化物中o-相和m-相的共存，形成固溶体，提升了锂锰氧化物在电池充电状态下的结构稳定性；两相共存形成的固溶体存在氧空位，能够促进锂离子的脱出，从而能够提升锂锰氧化物的充电比容量；同时，通过固溶体协同效应，能够增加Mn-O键的稳定性，从而能够抑制锂锰氧化物中的Mn溶出，进而改善电池的使用寿命。
由实施例1-5、7-10和12-22与其它实施例的比较可以看出，当满足0.05≤I A/I B≤0.9，或6≤I A/I B≤20时，锂离子扣式电池能够具有更高的充电比容量，可能的原因在于，锂锰氧化物中m-相与o-相的含量存在较大差异，能够协同作用形成固溶体，促进锂锰氧化物 中Li离子的脱出，从而进一步提升锂锰氧化物的充电比容量。由实施例1-2、5-10和13-22与其它实施例的比较可以看出，当满足0.75≤W A/W B≤1.65时，Mn溶出量进一步减少，可能的原因在于，此时，锂锰氧化物中的o-相和m-相的半峰宽均较窄，结构稳定性更高，从而进一步抑制锂锰氧化物中的Mn溶出。
尽管已经演示和描述了说明性实施例，本领域技术人员应该理解上述实施例不能被解释为对本申请的限制，并且可以在不脱离本申请的精神、原理及范围的情况下对实施例进行改变，替代和修改。

Claims (12)

  1. 一种正极活性材料，所述正极活性材料包含锂锰氧化物，所述正极活性材料的X射线衍射图谱在14.3°至16.3°范围内具有第一衍射峰，且在17.3°至19.3°范围内具有第二衍射峰。
  2. 根据权利要求1所述的正极活性材料，其中，所述正极活性材料满足下列条件中的至少一者：
    (1)所述正极活性材料的X射线衍射图谱在45.7°至47.7°范围内具有第三衍射峰；
    (2)所述第一衍射峰的峰强为I A，所述第二衍射峰的峰强为I B，满足：0.05≤I A/I B≤20。
  3. 根据权利要求2所述的正极活性材料，其中，0.05≤I A/I B≤0.9，或6≤I A/I B≤20。
  4. 根据权利要求1所述的正极活性材料，其中，所述第一衍射峰的半峰宽为W A，第二衍射峰的半峰宽为W B，满足：0.3≤W A/W B≤3。
  5. 根据权利要求4所述的正极活性材料，其中，0.75≤W A/W B≤1.65。
  6. 根据权利要求2所述的正极活性材料，其中，所述第二衍射峰的峰强为I B，所述第三衍射峰的峰强为I C，满足：0.08≤I C/I B≤0.35。
  7. 根据权利要求1所述的正极活性材料，其中，所述正极活性材料满足下列条件中的至少一者：
    (1)所述锂锰氧化物包含M元素，M元素包括Cr、Al、Mg、Ti、Y、Nb、W、Ga、Zr、V、Sr、Mo、Ru、Ag、Sn、Au、La、Ce、Pr、Nd、Sm、Gd、Cu、Na、Zn、Fe、Co、Ni或Ca中的至少一种，所述锂锰氧化物中M元素与Mn元素的摩尔比为0.001∶1至0.1∶1；
    (2)所述正极活性材料的平均粒径Dv50为2μm至35μm；
    (3)所述锂锰氧化物具有片层状结构；
    (4)所述锂锰氧化物中Li元素与Mn元素的摩尔比为0.9至1.15；
    (5)所述锂锰氧化物包括Li xMn yM zO 2，其中，0.9≤x≤1.15，0.9≤y≤1，0≤z≤ 0.1，M包括Cr、Al、Mg、Ti、Y、Nb、W、Ga、Zr、V、Sr、Mo、Ru、Ag、Sn、Au、La、Ce、Pr、Nd、Sm、Gd、Cu、Na、Zn、Fe、Co、Ni或Ca中的至少一种。
  8. 根据权利要求1所述的正极活性材料，其中，将所述正极活性材料与锂金属组装成扣式电池，所述扣式电池的首圈充电的电压容量微分dQ/dV曲线在3.5V-3.7V和3.85V-4.05V范围内具有特征峰，所述扣式电池的首圈放电的电压容量微分dQ/dV曲线在3.8V-4.0V范围内具有特征峰。
  9. 一种正极活性材料的制备方法，所述方法包括：
    将含锰氧化物、锂源和可选的M元素源，进行混合得到混合物；将所述混合物在第一气氛条件以及第一温度条件下进行煅烧，得到所述正极活性材料；
    其中，所述含锰氧化物和所述锂源按照锂锰摩尔比为0.90-1.15的范围进行混合；
    所述第一气氛条件为惰性气氛。
  10. 根据权利要求9所述的正极活性材料的制备方法，其中，所述制备方法满足下列条件中的至少一者：
    (1)所述惰性气氛包括氮气、氩气或氦气中的至少一种；
    (2)所述第一温度为880℃-1100℃；
    (3)所述煅烧的时间为5小时至20小时；
    (4)所述含锰氧化物包括Mn 3O 4；
    (5)所述M元素包括Cr、Al、Mg、Ti、Y、Nb、W、Ga、Zr、V、Sr、Mo、Ru、Ag、Sn、Au、La、Ce、Pr、Nd、Sm、Gd、Cu、Na、Zn、Fe、Co、Ni或Ca中的至少一种；
    (6)所述M元素源包括CrO 2、Al 2O 3、MgO、TiO 2或Y 2O 3中的至少一种；
    (7)所述含锰氧化物和所述M元素源按照所述M元素与Mn元素的摩尔比M∶Mn为0.001∶1至0.1∶1的范围进行混合；
    (8)所述锂源包括氢氧化锂、碳酸锂、乙酸锂、硝酸锂或硫酸锂中的至少一种。
  11. 一种电化学装置，其中，所述电化学装置包括根据权利要求1-8中任一项所述的正 极活性材料或根据权利要求9-10中任一项所述正极活性材料的制备方法所制备的正极活性材料。
  12. 一种用电装置，其包括根据权利要求11所述的电化学装置。
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