WO2023015489A1 - 一种电化学装置及电子装置 - Google Patents

一种电化学装置及电子装置 Download PDF

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WO2023015489A1
WO2023015489A1 PCT/CN2021/112091 CN2021112091W WO2023015489A1 WO 2023015489 A1 WO2023015489 A1 WO 2023015489A1 CN 2021112091 W CN2021112091 W CN 2021112091W WO 2023015489 A1 WO2023015489 A1 WO 2023015489A1
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positive electrode
active material
electrode active
electrochemical device
lithium
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PCT/CN2021/112091
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English (en)
French (fr)
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袁国霞
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宁德新能源科技有限公司
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Priority to CN202180002480.3A priority Critical patent/CN113812021A/zh
Priority to PCT/CN2021/112091 priority patent/WO2023015489A1/zh
Priority to KR1020237038801A priority patent/KR20230162124A/ko
Publication of WO2023015489A1 publication Critical patent/WO2023015489A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/502—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese for non-aqueous cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of electrochemical technology, in particular to an electrochemical device and an electronic device.
  • Lithium-ion batteries have many advantages such as large volume and mass energy density, long cycle life, high nominal voltage, low self-discharge rate, small size, and light weight, and have a wide range of applications in the field of consumer electronics. With the rapid development of electric vehicles and mobile electronic devices in recent years, the market has put forward higher requirements for lithium-ion batteries, for example, lithium-ion batteries are required to be stable in high-temperature environments.
  • the current lithium-ion battery has a serious specific capacity fading at high temperature. This is because the high temperature promotes the occurrence of side reactions inside the lithium-ion battery, resulting in the destruction of the structure of the positive electrode active material, which affects the stability and service life of the lithium-ion battery. Therefore, there is an urgent need for a lithium-ion battery with a long service life at high temperatures.
  • the purpose of the present application is to provide an electrochemical device and an electronic device to improve the high-temperature cycle performance of the electrochemical device.
  • the specific technical scheme is as follows:
  • the first aspect of the present application provides an electrochemical device, including a positive electrode, the positive electrode includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, the positive electrode active material layer includes lithium manganese oxide, lithium manganese The oxide contains aluminum element and sodium element. Based on the weight of the positive electrode active material, the content of aluminum element is A%, and the content of sodium element is B%, satisfying 0.01 ⁇ A ⁇ 2, 0.001 ⁇ B ⁇ 1.
  • the positive electrode active material layer of the present application contains lithium manganese oxide, and the lithium manganese oxide contains aluminum element and sodium element.
  • Manganese (Mn) dissolution can be reduced by controlling the content of the aluminum element and the sodium element within the above range, thereby improving the high-temperature cycle performance of the electrochemical device. Without being limited to any theory, this may be due to the fact that the aluminum element in the above content range can enhance the stability of the Mn-O bond in the lithium manganese oxide, improve the crystal structure of the lithium manganese oxide, and reduce the ginger Taylor (Jahn-Tellen) of the manganese element.
  • the present application can reduce the dissolution of Mn by controlling the content of aluminum and sodium within the above range, and at the same time reduce the influence of sodium on the performance of the positive electrode, thereby improving the cycle performance and storage capacity retention performance of the electrochemical device.
  • the lithium manganese oxide of the present application may include but not limited to: modified LiMn 2 O 4 (hereinafter referred to as modified LMO).
  • modified LMO modified LiMn 2 O 4
  • the present application has no special limitation on the modification method of the lithium manganese oxide, for example, an aluminum-containing compound may be added during the synthesis of LiMn 2 O 4 , so that the lithium manganese oxide of the present application contains aluminum element.
  • the positive electrode active material layer of the present application can be arranged on at least one surface of the positive electrode current collector, for example, the positive electrode active material layer is arranged on one surface of the positive electrode current collector, or the positive electrode active material layer is arranged on both surfaces of the positive electrode current collector superior.
  • the electrochemical device of the present application satisfies at least one of the conditions (a) or (b): (a) 0.011 ⁇ A+B ⁇ 2.5; (b) 0.1 ⁇ A/B ⁇ 125.
  • the lithium manganese oxide of the present application further contains niobium element, based on the weight of the positive electrode active material, the content of the niobium element is C%, which satisfies 0 ⁇ C ⁇ 1.
  • the inventors of the present application found that the niobium element within the above content range can further improve the crystal structure of lithium manganese oxide, so that the number of active crystal faces (111) of lithium manganese oxide exposed on the outer surface is reduced, That is, the number of active crystal faces (111) in contact with the electrolyte is reduced, thereby reducing the side reaction between the electrolyte and the surface of lithium manganese oxide, further reducing the dissolution of Mn, thereby improving the high-temperature cycle performance and storage capacity retention performance of the electrochemical device.
  • the content of niobium element in the positive electrode active material layer can be controlled by adding a niobium-containing compound and controlling the amount of the niobium-containing compound during the modification process of the lithium manganese oxide.
  • the electrochemical device of the present application satisfies at least one of the conditions (c) to (d): (c) 0.011 ⁇ A+C ⁇ 2.8; (d) 0.011 ⁇ A+B +C ⁇ 3.3; (e)0 ⁇ C/B ⁇ 40.
  • the lithium manganese oxide satisfies at least one of the conditions (f) to (g): (f) lithium The first diffraction peak corresponding to the (111) crystal plane appears in manganese oxide at 18° to 20°, and the peak intensity of the first diffraction peak is I(111); (g) lithium manganese oxide is at 43° to 45° A second diffraction peak corresponding to the (400) crystal plane appears at the place, and the peak intensity of the second diffraction peak is I(400); (h) lithium manganese oxide appears corresponding to the (440) crystal plane at 63 ° to 65 °
  • the electrochemical device of the present application satisfies at least one of the conditions (i) to (j): (i) 0.25 ⁇ I(400)/I(111) ⁇ 0.55; (j )0.35 ⁇ I(440)/I(400) ⁇ 0.55.
  • the inventors of the present application found that by controlling I(400)/I(111) within the above range, and/or controlling I(440)/I(400) within the above range, the lithium The crystal structure of manganese oxide reduces the number of active crystal faces (111) of lithium manganese oxide exposed on the outer surface, thereby reducing the side reaction between the electrolyte and the surface of lithium manganese oxide, further reducing the dissolution of Mn, and improving the electrochemical device. Excellent high temperature cycle performance and storage capacity retention performance.
  • the positive electrode active material layer may further include lithium nickel cobalt manganese acid oxide, and based on the weight of the positive electrode active material, the weight percentage of the cobalt element is less than or equal to 15%.
  • Lithium nickel cobalt manganese acid oxide can also be included in the positive electrode active material layer of the present application, and the residual alkali (for example Li 2 CO 3 or LiOH) on the surface of lithium nickel cobalt manganese acid oxide can react with hydrofluoric acid (HF) in the electrolytic solution ) reaction, reduce the acidity of the electrolyte, and further reduce the dissolution of Mn, thereby improving the high-temperature cycle performance and storage capacity retention performance of the electrochemical device. Therefore, in this application, based on the weight of the positive electrode active material, controlling the weight percentage of cobalt in the positive electrode active material to be less than or equal to 15% can further improve the high-temperature cycle performance and storage capacity retention performance of the electrochemical device while reducing production costs.
  • the weight percentage of cobalt in the positive electrode active material based on the weight of the positive electrode active material, controlling the weight percentage of cobalt in the positive electrode active material to be less than or equal to 15% can further improve the high-temperature cycle performance and storage capacity retention performance of the electro
  • the molar ratio of nickel to manganese in the positive electrode active material layer is 0.02:1 to 0.7:1, and the molar ratio of cobalt to manganese is less than or equal to 0.3:1.
  • the nickel element, manganese element and cobalt element in the positive electrode active material layer can be rationally configured, thereby obtaining An electrochemical device with excellent high-temperature cycle performance and storage capacity retention performance.
  • the positive electrode active material layer may further contain lithium iron phosphate (LiFePO 4 , ie LFP), wherein the average particle size of lithium iron phosphate is smaller than the average particle size of lithium manganese oxide.
  • LiFePO 4 lithium iron phosphate
  • ie LFP lithium iron phosphate
  • lithium iron phosphate is present on at least part of the surface of lithium manganese oxide, that is, lithium manganese oxide can be partially coated with lithium iron phosphate, or it can be completely coated, Thereby suppressing the side reaction on the surface of the lithium manganese oxide, and further improving the high-temperature cycle performance and storage capacity retention performance of the electrochemical device.
  • the molar ratio of iron element to manganese element in the positive electrode active material layer is 0.02:1 to 0.25:1.
  • the iron element and manganese element in the positive electrode active material layer can be rationally arranged, and the side reaction on the surface of lithium manganese oxide can be suppressed, thereby further improving the electrochemical device. High temperature cycle performance and storage capacity retention performance.
  • the weight percentage of lithium iron phosphate is ⁇ 30%.
  • the electrochemical device can have high energy density while further improving the high-temperature cycle performance and storage capacity retention performance of the electrochemical device.
  • the compacted density P of the positive electrode active material layer is 2.7 g/cm 3 ⁇ P ⁇ 4.0 g/cm 3 .
  • the compacted density of the positive electrode active material layer is too low (for example, less than 2.7g/cm 3 )
  • the compacted density of the positive electrode active material layer is too high (for example, higher than 4.0 g/cm 3 )
  • the positive electrode is more prone to brittle fracture, which is not conducive to the safety of the electrochemical device.
  • the electrochemical device can have high energy density and excellent safety.
  • the present application provides an electrochemical device and an electronic device.
  • the positive electrode of the electrochemical device includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode active material layer contains lithium manganese oxide, wherein Lithium manganese oxide contains aluminum element and sodium element, and by controlling the content A% of aluminum element and the content B% of sodium element in the positive electrode active material to satisfy 0.01 ⁇ A ⁇ 2, 0.001 ⁇ B ⁇ 1, the lithium manganese oxide can be improved crystal structure, reduce the dissolution of manganese, improve the cycle performance of the electrochemical device, especially the cycle performance under high temperature conditions, and can also improve the high temperature storage performance of the electrochemical device.
  • FIG. 1 is an XRD pattern of the positive electrode sheet powder of Example 35 of the present application.
  • the present application is explained by taking the lithium-ion battery as an example of the electrochemical device, but the electrochemical device of the present application is not limited to the lithium-ion battery.
  • the first aspect of the present application provides an electrochemical device, including a positive electrode, the positive electrode includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, the positive electrode active material layer includes lithium manganese oxide, lithium manganese The oxide contains aluminum element and sodium element. Based on the total weight of the positive electrode active material, the content of aluminum element is A%, and the content of sodium element is B%, satisfying 0.01 ⁇ A ⁇ 2, 0.001 ⁇ B ⁇ 1. In one embodiment of the present application, 0.49 ⁇ A ⁇ 1.8, 0.001 ⁇ B ⁇ 0.5.
  • the positive electrode active material layer of the present application contains lithium manganese oxide, and the lithium manganese oxide contains aluminum element and sodium element.
  • Manganese (Mn) dissolution can be reduced by controlling the content of the aluminum element and the sodium element within the above range, thereby improving the high-temperature cycle performance of the electrochemical device. Without being limited to any theory, this may be due to the fact that the aluminum element in the above content range can enhance the stability of the Mn-O bond in the lithium manganese oxide, improve the crystal structure of the lithium manganese oxide, and reduce the ginger Taylor (Jahn-Tellen) of the manganese element.
  • the present application can reduce the dissolution of Mn by controlling the content of aluminum and sodium within the above range, and at the same time reduce the influence of sodium on the performance of the positive electrode, thereby improving the cycle performance and storage capacity retention performance of the electrochemical device.
  • the lithium manganese oxide of the present application may include but not limited to: modified LiMn 2 O 4 (hereinafter referred to as modified LMO).
  • modified LMO modified LiMn 2 O 4
  • the present application has no special limitation on the modification method of the lithium manganese oxide, for example, an aluminum-containing compound may be added during the synthesis of LiMn 2 O 4 , so that the lithium manganese oxide of the present application contains aluminum element.
  • the positive electrode active material layer of the present application can be arranged on at least one surface of the positive electrode current collector, for example, the positive electrode active material layer is arranged on one surface of the positive electrode current collector, or the positive electrode active material layer is arranged on both surfaces of the positive electrode current collector superior.
  • the electrochemical device of the present application satisfies at least one of the conditions (a) or (b): (a) 0.011 ⁇ A+B ⁇ 2.5; (b) 0.1 ⁇ A/B ⁇ 125.
  • A+B can be 0.011, 0.03, 0.05, 0.07, 0.1, 0.3, 0.5, 0.9, 1.0, 1.1, 1.3, 1.5, 1.7, 1.9, 2.0, 2.5 or any two values above. range of composition.
  • A/B can be 0.1, 0.3, 0.5, 0.7, 0.9, 1.0, 3.0, 5.0, 7.0, 10, 15, 20, 25, 40, 60, 80, 100, 110 , 120, 125 or a range composed of any two values above.
  • the present application controls the sum of the aluminum element content and the sodium element content in the positive electrode active material, that is, the value of A+B is within the above range, and/or, controls the aluminum element content and the sodium element content in the positive electrode active material
  • the ratio of the element content that is, the value of A/B within the above range, can obtain an electrochemical device with excellent high-temperature cycle performance and storage capacity retention performance.
  • A/B is too large, the cycle performance of the electrochemical device can be limited.
  • the value of A/B is too small, it may affect the reversible capacity of the electrochemical device.
  • the lithium manganese oxide further contains niobium element, based on the total weight of the positive electrode active material, the content of niobium element is C%, satisfying 0 ⁇ C ⁇ 1. In some embodiments, 0.0001 ⁇ C ⁇ 0.7. In some embodiments, 0.0001 ⁇ C ⁇ 0.5. In some embodiments, C may be 0.001, 0.003, 0.005, 0.008, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0 or a range composed of any two values above.
  • the inventors of the present application found that the niobium element within the above content range can further improve the crystal structure of lithium manganese oxide, so that the number of active crystal faces (111) of lithium manganese oxide exposed on the outer surface is reduced, That is, the number of active crystal faces (111) in contact with the electrolyte is reduced, thereby reducing the side reaction between the electrolyte and the surface of lithium manganese oxide, further reducing the dissolution of Mn, thereby improving the high-temperature cycle performance and storage capacity retention performance of the electrochemical device.
  • the content of niobium element in the positive electrode active material layer can be controlled by adding a niobium-containing compound and controlling the amount of the niobium-containing compound during the modification process of the lithium manganese oxide.
  • the present application has no special limitation on niobium-containing compounds, for example, it may include but not limited to: Nb 2 O 5 , NbF 5 .
  • the electrochemical device of the present application satisfies the condition 0.01 ⁇ A+C ⁇ 2.8. In some embodiments, 0.011 ⁇ A+C ⁇ 2. In some embodiments, 0.07 ⁇ A+C ⁇ 2.3. In some embodiments, 0.01 ⁇ A+C ⁇ 1.6. In some embodiments A+C can be 0.011, 0.03, 0.05, 0.07, 0.09, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8 or It is the range formed by any two values above.
  • the performance of the electrochemical device is in a better state.
  • the electrochemical device cycle The performance improvement is limited and may affect the reversible capacity of the electrochemical device.
  • the electrochemical device of the present application satisfies the condition 0.011 ⁇ A+B+C ⁇ 3.3 and in some embodiments 0.1 ⁇ A+B+C ⁇ 2.0.
  • A+B+C can be 0.011, 0.05, 0.07, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.5, 3.0, 3.3 or any two of the above range of values.
  • the electrochemical device has better cycle performance and storage performance.
  • the electrochemical device of the present application satisfies the condition 0 ⁇ C/B ⁇ 40. In some embodiments, 0 ⁇ C/B ⁇ 10. In some embodiments, 0 ⁇ C/B ⁇ 5. In some embodiments, 0 ⁇ C/B ⁇ 3. In some embodiments, C/B can be 0.0001, 0.0005, 0.001, 0.003, 0.005, 0.007, 0.009, 0.01, 0.03, 0.05, 0.07, 0.09, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0, 1.2, 1.5 , 1.7, 1.9, 2.0, 3.0, 5.0, 7.0, 9.0, 10.0, 15, 20, 25, 30, 35, 40 or a range composed of any two of the above values.
  • an electrochemical device with excellent high-temperature cycle performance and storage capacity retention performance can be obtained.
  • the value of C/B is too high, it may affect the cycle performance of the electrochemical device.
  • the value of C/B is too low, the protection of the active crystal face (111) of lithium manganese oxide is small, the inhibition of Mn dissolution is limited, and the loss of reversible capacity of the electrochemical device may be increased.
  • the first diffraction corresponding to the (111) crystal plane appears in lithium manganese oxide at 18° to 20° Peak, the peak intensity of the first diffraction peak is I(111).
  • the second diffraction corresponding to the (400) crystal plane appears in lithium manganese oxide at 43° to 45° peak, the peak intensity of the second diffraction peak is I(400).
  • the third diffraction corresponding to the (440) crystal plane appears in lithium manganese oxide at 63° to 65° Peak, the peak intensity of the third diffraction peak is I(440).
  • the positive electrode sheet of the present application includes a positive electrode active material layer, which contains a positive electrode active material.
  • the main component of the positive electrode active material is lithium manganese oxide.
  • the XRD test shows that the lithium manganese oxide of the present application contains (111) crystal plane, (400) crystal plane and (440) crystal plane.
  • the electrochemical device of the present application satisfies 0.25 ⁇ I(400)/I(111) ⁇ 0.55.
  • the electrochemical device of the present application satisfies 0.35 ⁇ I(440)/I(400) ⁇ 0.55.
  • the crystal structure of lithium manganese oxide can be further improved, The number of active crystal faces (111) of lithium manganese oxide exposed on the outer surface is reduced, thereby reducing the side reaction between the electrolyte and the surface of lithium manganese oxide, further reducing the dissolution of Mn, and improving the high-temperature cycle performance and storage capacity of the electrochemical device Maintain performance.
  • the positive electrode active material further includes M element, and the M element includes at least one of Cu, Fe, Mg, Ti, Zr, Zn, W, Sr, and Y.
  • the M element may include Mg, and at least one of Cu, Fe, Ti, Zr, Zn, W, Sr, and Y.
  • the content of M element is less than or equal to 5%.
  • the content of M element can be 0.01%, 0.03%, 0.05%, 0.07%, 0.1%, 0.3%, 0.5%, 0.7%, 1.0%, 2.0%, 3.0%, 5.0%, or any of the above A range of two numeric values.
  • the positive electrode active material further includes element X, and the element X includes at least one of S, P, B, F, or Cl.
  • the content of element X is less than or equal to 3%. In some embodiments, the content of element X can be 0.01%, 0.03%, 0.05%, 0.07%, 0.1%, 0.3%, 0.5%, 0.7%, 1.0%, 2.0%, 3.0%, or any two values above composed range.
  • the positive electrode active material layer may further include lithium nickel cobalt manganese acid oxide, and based on the weight of the positive electrode active material, the weight percentage of cobalt is less than or equal to 15%.
  • lithium nickel cobalt manganese acid oxide can also be included in the positive electrode active material layer of the present application, and the residual alkali (for example Li 2 CO 3 or LiOH) on the surface of lithium nickel cobalt manganese acid oxide oxide can be combined with the electrolyte in the electrolyte.
  • the hydrofluoric acid (HF) reaction reduces the acidity of the electrolyte and further reduces the dissolution of Mn, thereby improving the high-temperature cycle performance and storage capacity retention performance of the electrochemical device.
  • the content of cobalt is too high, the production cost of the electrochemical device will increase.
  • the weight percentage of cobalt in the lithium nickel cobalt manganate oxide is controlled to be less than or equal to 15%, which can further improve the high temperature cycle performance and storage capacity retention performance of the electrochemical device. reduce manufacturing cost.
  • the present application has no special limitation on the lithium nickel cobalt manganese acid oxide, as long as the purpose of the present application can be achieved.
  • the lithium nickel cobalt manganese acid oxide can be lithium nickel cobalt manganese oxide (hereinafter referred to as NCM).
  • the lithium nickel cobalt manganese oxide may be single crystal lithium nickel cobalt manganese oxide or polycrystalline lithium nickel cobalt manganese oxide.
  • the molar ratio of nickel element to manganese element in the positive electrode active material layer is 0.02:1 to 0.7:1.
  • the molar ratio of cobalt element to manganese element in the positive electrode active material layer is less than or equal to 0.3:1.
  • the nickel element, manganese element and cobalt element in the positive electrode active material layer can be reasonably configuration, thereby obtaining an electrochemical device with excellent high-temperature cycle performance and storage capacity retention performance.
  • the positive electrode active material layer may further contain lithium iron phosphate (LiFePO 4 , ie LFP), wherein the average particle size of lithium iron phosphate is smaller than the average particle size of lithium manganese oxide.
  • LiFePO 4 lithium iron phosphate
  • ie LFP lithium iron phosphate
  • the average particle size of the lithium iron phosphate is less than or equal to 2 ⁇ m. In some embodiments, the average particle size of lithium iron phosphate is less than or equal to 1.8 ⁇ m. In some embodiments, the average particle size of lithium iron phosphate is less than or equal to 1.5 ⁇ m. In some embodiments, the average particle size of the lithium iron phosphate is less than or equal to 1.2 ⁇ m. In some embodiments, the average particle size of the lithium iron phosphate is less than or equal to 1.0 ⁇ m.
  • One embodiment of the present application utilizes the characteristics of the small particle size of lithium iron phosphate, so that at least part of the surface of the lithium iron phosphate has lithium iron phosphate, that is, the lithium manganese oxide can be partially coated with lithium iron phosphate, or it can be completely Coating, thereby inhibiting the side reaction on the surface of lithium manganese oxide, further improving the high-temperature cycle performance and storage capacity retention performance of the electrochemical device.
  • the molar ratio of iron element to manganese element in the positive electrode active material layer is 0.02:1 to 0.25:1. In some embodiments, the molar ratio of the iron element to the manganese element in the positive electrode active material layer is 0.03:1 to 0.13:1. In some embodiments, the molar ratio of the iron element to the manganese element in the positive electrode active material layer is 0.05:1 to 0.12:1. In some embodiments, the molar ratio of the iron element to the manganese element in the positive electrode active material layer is 0.03:1 to 0.13:1.
  • the iron element and manganese element in the positive electrode active material layer can be rationally arranged, and the side reaction on the surface of lithium manganese oxide can be suppressed, thereby further improving the electrochemical device. High temperature cycle performance and storage capacity retention performance.
  • the weight percentage of lithium iron phosphate is ⁇ 30%.
  • the electrochemical device can have high energy density while further improving the high-temperature cycle performance and storage capacity retention performance of the electrochemical device.
  • the compacted density P of the positive electrode active material layer is 2.7 g/cm 3 ⁇ P ⁇ 4.0 g/cm 3 .
  • the compacted density of the positive electrode active material layer is too low (for example, less than 2.7g/cm 3 )
  • the compacted density of the positive electrode active material layer is too high (for example, higher than 4.0 g/cm 3 )
  • the positive electrode is more prone to brittle fracture, which is not conducive to the safety of the electrochemical device.
  • the electrochemical device can have high energy density and excellent safety.
  • the present application has no special limitation on the preparation method of lithium manganese oxide, and the preparation method known to those skilled in the art can be adopted.
  • an aluminum -containing compound such as Al 2 O 3 , Al(OH) 3 , AlF 3
  • the present application can realize the change of the aluminum element in the positive electrode active material layer by adjusting the content of the aluminum element in the lithium manganese oxide, such as controlling the addition of the aluminum-containing compound; by adjusting the sodium in the precursor of LiMn 2 O 4
  • the content of the element can realize the change of the content of the sodium element in the positive electrode active material layer.
  • the application does not specifically limit the adjustment process, as long as the purpose of the application can be achieved.
  • a positive electrode sheet in this application is not particularly limited, as long as the purpose of this application can be achieved.
  • a positive electrode sheet typically includes a positive current collector and a positive active material layer.
  • the positive electrode current collector is not particularly limited, and may be any positive electrode current collector in the art, such as aluminum foil, aluminum alloy foil, or a composite current collector.
  • a negative electrode sheet in this application is not particularly limited, as long as the purpose of this application can be achieved.
  • a negative electrode sheet generally includes a negative electrode current collector and a negative electrode active material layer.
  • the negative electrode current collector is not particularly limited, and materials such as metal foil or porous metal plate can be used, such as foil or porous plate of metals such as copper, nickel, titanium or iron or their alloys, such as copper foil.
  • the negative active material layer includes a negative active material, a conductive agent, a binder, and a thickener.
  • the negative active material is not particularly limited, and any negative active material in the art may be used.
  • the conductive agent can be graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon At least one of dots, carbon nanotubes, graphene or carbon nanofibers;
  • the binder can be styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol At least one of butyral (PVB), water-based acrylic resin (water-based acrylic resin) or carboxymethyl cellulose (CMC); the thickener may be carboxymethyl cellulose (CMC).
  • the substrate of the isolation film of the present application includes, but is not limited to, selected from polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyimide (PI) or aramid at least one of the
  • polyethylene includes at least one component selected from high-density polyethylene, low-density polyethylene, and ultra-high molecular weight polyethylene.
  • polyethylene and polypropylene have an excellent effect on preventing short circuits and can improve the stability of electrochemical devices through the shutdown effect.
  • the substrate can be a single-layer structure or a multi-layer composite structure mixed with a thickness of 3 ⁇ m to 20 ⁇ m.
  • the lithium ion battery of the present application also includes an electrolyte, which can be one or more of gel electrolyte, solid electrolyte and electrolyte, and the electrolyte includes lithium salt and non-aqueous solvent.
  • the lithium salt is selected from LiPF 6 , LiBF 4 , LiAsF 6 , 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 , LiSiF 6 , LiBOB and lithium difluoroborate is selected from LiPF 6 , LiBF 4 , LiAsF 6 , 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 LiSiF 6 , LiBOB and lithium difluoroborate
  • LiPF 6 may be selected as a lithium salt because it can give high ion conductivity and improve cycle characteristics.
  • the non-aqueous solvent can be carbonate compound, carboxylate compound, ether compound, other organic solvent or their combination.
  • the above-mentioned carbonate compound can be a chain carbonate compound, a cyclic carbonate compound, a fluorocarbonate compound or a combination thereof.
  • Examples of the aforementioned chain carbonate compounds are dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), carbonic acid Methyl ethyl ester (MEC) and combinations thereof.
  • Examples of cyclic carbonate compounds are ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylethylene carbonate (VEC), and combinations thereof.
  • Examples of fluorocarbonate compounds are fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate Ethyl carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-dicarbonate Fluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethylethylene carbonate, and combinations thereof.
  • Examples of the above carboxylate compounds are methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone , decanolactone, valerolactone, mevalonolactone, caprolactone, and combinations thereof.
  • Examples of the aforementioned ether compounds are dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethyl Oxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, and combinations thereof.
  • Examples of the aforementioned other organic solvents are dimethylsulfoxide, 1,2-dioxolane, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, Formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphate esters, and combinations thereof.
  • the second aspect of the present application provides an electronic device comprising the electrochemical device described in the above embodiments of the present application.
  • the electronic device of the present application is not particularly limited, and it may be used in any electronic device known in the prior art.
  • electronic devices may include, but are not limited to, notebook computers, pen-based computers, mobile computers, e-book players, cellular phones, portable fax machines, portable copiers, portable printers, headsets, VCRs, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, Lighting appliances, toys, game consoles, clocks, electric tools, flashlights, cameras, large household storage batteries and lithium-ion capacitors, etc.
  • a lithium-ion battery can be manufactured through the following process: overlap the positive electrode and the negative electrode through the separator, and put it into the case after winding, folding, etc. as required, inject the electrolyte into the case and seal it.
  • anti-overcurrent elements, guide plates, etc. can also be placed in the casing according to needs, so as to prevent the internal pressure of the lithium-ion battery from rising and overcharging and discharging.
  • the present application provides an electrochemical device and an electronic device.
  • the positive electrode of the electrochemical device includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode active material layer contains lithium manganese oxide, wherein Lithium manganese oxide contains aluminum element and sodium element, and by controlling the content A% of aluminum element and the content B% of sodium element in the positive electrode active material to satisfy 0.01 ⁇ A ⁇ 2, 0.001 ⁇ B ⁇ 1, the lithium manganese oxide can be improved crystal structure, reduce the dissolution of manganese, improve the cycle performance of the electrochemical device, especially the cycle performance under high temperature conditions, and can also improve the high temperature storage performance of the electrochemical device.
  • Disassemble the lithium-ion battery discharged to a voltage of 2.8V then dissolve the positive active material layer on the dried positive electrode sheet with a mixed solvent (for example, 0.4g positive active material uses 10ml (nitric acid and hydrochloric acid according to 1: 1 mixed) mixed solvent of aqua regia and 2ml HF), set the volume to 100mL, and then use ICP (Inductively coupled plasma, inductively coupled plasma) analyzer to test the content of Al, Na, Nb and other elements in the solution.
  • a mixed solvent for example, 0.4g positive active material uses 10ml (nitric acid and hydrochloric acid according to 1: 1 mixed) mixed solvent of aqua regia and 2ml HF
  • ICP Inductively coupled plasma, inductively coupled plasma
  • Disassemble the lithium-ion battery discharged to a voltage of 2.8V then take out the positive electrode sheet, scrape off the positive electrode active material layer with a scraper to obtain the positive electrode active material layer powder, and then place the positive electrode active material layer powder on the XRD testing instrument (Model Bruker, D8) in the sample stage, using a scan rate of 2°/min, and a scan angle range of 10° to 90°, to obtain an XRD diffraction pattern.
  • the XRD testing instrument Model Bruker, D8
  • the test instrument is OXFORD EDS (X-max-20mm 2 ).
  • Compacted density P m/[5cm ⁇ 5cm ⁇ (d0-d)], unit g/cm 3 .
  • the compacted density of the positive electrode active material layer is the average value of 5 positive electrode sheets.
  • 25°C cycle capacity retention (discharge capacity of the 1000th cycle/discharge capacity of the first cycle) ⁇ 100%.
  • Lithium-ion battery high temperature storage performance test
  • Capacity retention rate of lithium ion battery capacity after storage / capacity before storage ⁇ 100%.
  • lithium carbonate 203.3g (wherein lithium element content is 18.71%), manganese dioxide 1000.0g (wherein Mn element content is 60.22%, Na element content is 0.27%), aluminum oxide 29.96g (aluminum element content 52.91%) ), mixed in a high-speed mixer at 300r/min for 20min, put the mixture in an air kiln, raised the temperature to 820°C at 5°C/min, kept it for 24h, took it out after natural cooling, and obtained lithium manganese oxide after passing through a 300-mesh sieve (ie modified LMO).
  • the prepared positive electrode active material, binder polyvinylidene fluoride (PVDF), conductive carbon black, and carbon nanotube (CNT) are mixed in a weight ratio of 95:2:1.8:1.2, and then NMP (N-methylpyrrolidone ) was used as a solvent, and was prepared under vacuum stirring to form a uniform transparent positive electrode slurry with a solid content of 75%.
  • PVDF binder polyvinylidene fluoride
  • CNT carbon nanotube
  • the positive electrode slurry is uniformly coated on one surface of an aluminum foil with a thickness of 9 ⁇ m, dried at 90° C., and cold pressed to obtain a positive electrode sheet with a total thickness of the positive electrode active material layer of 100 ⁇ m, and then on the other side of the positive electrode sheet Repeat the above steps on one surface to obtain a positive electrode sheet coated with a positive electrode active material layer on both sides. Cut the positive pole piece into a size of 74mm ⁇ 867mm and weld the tabs for use.
  • the aluminum element content in the positive electrode active material layer is 1.52%
  • the sodium element content is 0.26%
  • the compacted density of the positive electrode active material layer is 2.8g/cm 3 .
  • Negative active material artificial graphite, styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC) were mixed in a weight ratio of 98:1:1, and then deionized water was added as a solvent to prepare a slurry with a solid content of 70%. , and stir well.
  • the slurry is evenly coated on one surface of a copper foil with a thickness of 8 ⁇ m, dried at 110° C., and cold-pressed to obtain a negative electrode sheet with a negative active material layer coated on one side with a negative active material layer thickness of 150 ⁇ m.
  • a polyethylene (PE) porous polymer film with a thickness of 15 ⁇ m was used as the separator.
  • the non-aqueous organic solvent propylene carbonate (PC), ethylene carbonate (EC), and diethyl carbonate (DEC) are mixed according to a weight ratio of 1:1:1, and then added to the non-aqueous organic solvent.
  • LiPF 6 lithium hexafluorophosphate
  • the molar concentration of LiPF 6 in the electrolyte is 1.15mol/L.
  • the above prepared positive electrode sheet, separator, and negative electrode sheet are stacked in order, so that the separator is placed between the positive electrode sheet and the negative electrode sheet to play the role of isolation, and the electrode assembly is obtained by winding.
  • the preparation method is similar to that of Example 1, except that the content of elements shown in Table 1 and the particle size of lithium manganese oxide are different.
  • the preparation method is similar to that of Example 1, except that 1000.0 g of manganese dioxide is replaced by 850.3 g of trimanganese tetraoxide, and the differences in other parameters are shown in Table 1.
  • the preparation method is similar to that of Example 1, except that the niobium-containing compound Nb 2 O 5 is added to the lithium manganese oxide, and the content of the aluminum element in the positive electrode active material layer is adjusted to 1.01%, the content of the sodium element to 0.26%, and the content of the niobium element The content is 0.09%, and the compacted density of the positive electrode active material layer is adjusted to 3.0 g/cm 3 , except that it is the same as that of Example 1.
  • the preparation method is similar to that of Example 9, except that the content of elements shown in Table 1 and the particle size of lithium manganese oxide are different.
  • lithium carbonate 203.3g (wherein lithium element content is 18.71%), trimanganese tetraoxide 850.3g (wherein Mn element content is 70.82%, Na element content is 0.01%), aluminum sesquioxide 19.10g (aluminum element content 52.91%) %), niobium pentoxide 2.87g (niobium element content 79.46%) mixed in a high-speed mixer at 300r/min for 20min, the mixture was placed in an air kiln, heated to 750°C at 5°C/min, kept for 24h, naturally After cooling, take it out and pass through a 300-mesh sieve to obtain the finished product of lithium manganese oxide (that is, modified LMO).
  • the preparation method is similar to that of Example 11, except that the content of elements shown in Table 1 and the particle size of lithium manganese oxide are different.
  • the preparation method is similar to that of Example 9, except that the content of elements shown in Table 1 and the particle size of lithium manganese oxide are different.
  • the positive electrode active material modified LMO (its preparation method is similar to that of Example 9, the difference lies in the element content and particle size shown in Table 1) and polycrystalline lithium nickel cobalt manganese acid oxide (LiNi 0.60 Co 0.10 Mn 0.30 O 2 , recorded as NCM:15.8 (601030)) mixed to obtain a mixture, according to the parameters shown in Table 1, the proportioning is carried out so that the molar ratio of nickel and manganese, cobalt and manganese meet The proportions shown in Table 1, the element content and particle size in the positive electrode active material layer are shown in Table 1, and the compacted density of the positive electrode active material layer is 3.3 g/cm 3 , except that it is the same as Example 9.
  • the difference is that the element content, the average particle size of the modified LMO, the type and average particle size of the polycrystalline lithium nickel cobalt manganese acid oxide, and the moles of nickel and manganese are adjusted as shown in Table 1. Ratio, molar ratio of cobalt and manganese and other parameters.
  • the cathode active material modified LMO (its preparation method is similar to that of Example 11, except that the element content and particle size shown in Table 1) was mixed with polycrystalline lithium nickel cobalt manganate oxide (LiNi 0.50 Co 0.20 Mn 0.30 O 2 , recorded as NCM: 15.9 (502030)) and mixed to obtain a mixture.
  • the ratio of LMO to NCM was adjusted so that the molar ratio of nickel to manganese and the molar ratio of cobalt to manganese met the ratios shown in Table 1.
  • the element content and particle size in the positive electrode active material layer are shown in Table 1. Other than that, it is the same as in Example 11.
  • the cathode active material modified LMO (its preparation method is similar to that of Example 11, except that the element content and particle size shown in Table 1) was mixed with lithium iron phosphate (abbreviated as LFP) with an average particle size of 1 ⁇ m to obtain mixture. Adjust the ratio of LMO and LFP so that the molar ratio of iron and manganese satisfies the ratio shown in Table 1.
  • the element content and particle size in the positive electrode active material layer are shown in Table 1. Other than that, it is the same as in Example 11.
  • the preparation method is similar to that of Example 35, except that the parameters shown in Table 1 are different.
  • the cathode active material was modified LMO (its preparation method is similar to that of Example 9, the difference lies in the element content and particle size shown in Table 1), polycrystalline lithium nickel cobalt manganate oxide (LiNi 0.55 Co 0.15 Mn 0.30 O 2 , recorded as NCM:16.2 (551530)) and lithium iron phosphate (abbreviated as LFP) with an average particle size of 1 ⁇ m are mixed to obtain a mixture, so that the molar ratio of nickel and manganese, cobalt and manganese The molar ratio meets the ratio shown in Table 1, the element content and particle size in the positive electrode active material layer are shown in Table 1, and the compacted density of the positive electrode active material layer is 3.3 g/cm 3 . Other than that, it is the same as in Example 9.
  • the cathode active material is modified LMO (the preparation method is similar to that of Example 11, the difference lies in the element content and particle size shown in Table 1), single crystal lithium nickel cobalt manganate oxide (LiNi 0.55 Co 0.15 Mn 0.30 O 2 , recorded as NCM:6.4 (551530)) and lithium iron phosphate (abbreviated as LFP) with an average particle size of 1 ⁇ m are mixed to obtain a mixture such that the molar ratio of nickel and manganese, the ratio of cobalt and manganese The molar ratio meets the ratio shown in Table 1. Other than that, it is the same as in Example 11.
  • the cathode active material was modified LMO (its preparation method is similar to that of Example 9, the difference lies in the element content and particle size shown in Table 1), polycrystalline lithium nickel cobalt manganate oxide (LiNi 0.55 Co 0.15 Mn 0.30 O 2 , denoted as NCM:16.2 (551530)) and lithium iron phosphate (abbreviated as LFP) with a particle size of 1 ⁇ m are mixed to obtain a mixture, so that the molar ratio of nickel and manganese, the molar ratio of cobalt and manganese The ratio meets the ratio shown in Table 1. Except for this, the rest is the same as in Example 9.
  • the preparation method is similar to that of Example 39, except for the parameters shown in Table 1.
  • the positive electrode active material is LiMn 2 O 4 not doped with aluminum, the rest is the same as that of Embodiment 1.
  • the positive electrode active material is LiMn 2 O 4 not doped with aluminum, the rest is the same as that of Example 22.
  • the positive electrode active material is LiMn 2 O 4 not doped with aluminum, the rest is the same as that of Example 37.
  • the positive electrode active material layer has a lithium ion battery with an aluminum element content A% and a sodium element content B% of the present application, and 0.01 ⁇ A ⁇ 2, 0.001 ⁇ B ⁇ 1
  • the cycle capacity retention rate at 25°C, the cycle capacity retention rate at 45°C, and the storage capacity retention rate are all significantly improved, indicating that the lithium-ion battery of the present application has excellent cycle performance, especially high-temperature cycle performance, and excellent high-temperature storage performance. .
  • Lithium-ion batteries with the ranges of I(400)/I(111) and I(440)/I(400) in the present application have excellent cycle performance, especially high-temperature cycle performance, and excellent high-temperature storage performance.
  • the weight percent content of cobalt in the lithium nickel cobalt manganese acid oxide is different, which has an impact on the cycle performance and high temperature storage performance of the lithium ion battery, but as long as the lithium nickel cobalt manganese acid oxide If the content is within the scope of the present application, a lithium-ion battery with excellent cycle performance and high-temperature storage performance can be obtained.
  • the compaction density of the material layer usually also affects the cycle performance and high-temperature storage performance of lithium-ion batteries. It can also be seen from Examples 1 to 41 that as long as the above parameters are within the scope of this application, cycle performance, high-temperature storage performance, and high-temperature storage performance can be obtained. Lithium-ion battery with excellent performance.
  • Fig. 1 is the XRD diagram of the positive electrode sheet powder of Example 35 of the present application. It can be seen from Fig. 1 that the positive electrode active material of the present application has the first diffraction peak corresponding to the (111) crystal plane at 18° to 20°. , the second diffraction peak corresponding to the (400) crystal plane appears at 43° to 45°, and the third diffraction peak corresponding to the (440) crystal plane appears at 63° to 65°, satisfying 0.25 ⁇ I(400) /I(111) ⁇ 0.5, 0.35 ⁇ I(440)/I(400) ⁇ 0.55.

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Abstract

一种电化学装置及电子装置，包括正极，正极包括正极集流体和设置于正极集流体至少一个表面上的正极活性材料层，正极活性材料层包含锂锰氧化物，锂锰氧化物包含铝元素和钠元素，基于正极活性材料重量，铝元素含量为A％，钠元素含量为B％，满足0.01≤A≤2，0.001≤B≤1。由此，提高电化学装置的循环性能，尤其是高温条件下的循环性能，还能够提高电化学装置的高温储存性能。

Description

一种电化学装置及电子装置 技术领域
本申请涉及电化学技术领域，具体涉及一种电化学装置及电子装置。
背景技术
锂离子电池具有体积和质量能量密度大、循环寿命长、标称电压高、自放电率低、体积小、重量轻等许多优点，在消费电子领域具有广泛的应用。随着近年来电动汽车和可移动电子设备的高速发展，市场对锂离子电池提出了更高的要求，例如，要求锂离子电池在高温环境下也能稳定。
但是目前的锂离子电池在高温下比容量衰减比较严重，这是由于高温促使锂离子电池内部副反应的发生，导致正极活性材料的结构被破坏，影响了锂离子电池的稳定性和使用寿命。因此亟需一种在高温下具有长时间使用寿命的锂离子电池。
发明内容
本申请的目的在于提供一种电化学装置及电子装置，以提高电化学装置的高温循环性能。具体技术方案如下：
本申请的第一方面提供了一种电化学装置，包括正极，正极包括正极集流体和设置于正极集流体至少一个表面上的正极活性材料层，正极活性材料层包含锂锰氧化物，锂锰氧化物包含铝元素和钠元素，基于正极活性材料重量，铝元素含量为A％，钠元素含量为B％，满足0.01≤A≤2，0.001≤B≤1。
本申请的正极活性材料层包含锂锰氧化物，锂锰氧化物包含铝元素和钠元素。通过控制铝元素和钠元素的含量在上述范围内能够减少锰(Mn)溶出，从而改善电化学装置的高温循环性能。不限于任何理论，这可能是由于上述含量范围的铝元素能够增强锂锰氧化物中Mn-O键的稳定性，改善锂锰氧化物的晶体结构，降低锰元素的姜泰勒(Jahn-Tellen)效应；钠元素作为杂质元素，当在上述含量范围内时几乎不会对电化学装置的高温循环性能产生影响。因此整体上本申请通过控制铝元素和钠元素的含量在上述范围内，能够减少Mn溶出，同时降低钠元素对正极性能的影响，从而改善电化学装置的循环性能和存储容量保持性能。
本申请的锂锰氧化物可以包括但不限于：改性LiMn 2O 4(下文简称改性LMO)。本申请对锂锰氧化物的改性方法没有特别限制，例如，可以在合成LiMn 2O 4的过程中加入含铝 化合物，从而使本申请的锂锰氧化物中含有铝元素。
本申请的正极活性材料层可以设置在正极集流体的至少一个表面上，例如，正极活性材料层设置在正极集流体的一个表面上，或者，正极活性材料层设置在正极集流体的两个表面上。
在本申请的一种实施方案中，本申请的电化学装置满足条件(a)或(b)中的至少一者：(a)0.011≤A+B≤2.5；(b)0.1≤A/B≤125。
在本申请的一种实施方案中，0.03≤A+B﹤2，2﹤A/B≤125。
通过控制正极活性材料中的铝元素含量和钠元素含量之和，即A+B的值在上述范围内，和/或，控制正极活性材料中的铝元素含量与钠元素含量之比，即A/B的值在上述范围内，能够得到具有优良高温循环性能和存储容量保持性能的电化学装置。
在本申请的一种实施方案中，本申请的锂锰氧化物进一步包含铌元素，基于正极活性材料的重量，铌元素的含量为C％，满足0﹤C≤1。
不限于任何理论，本申请的发明人发现，上述含量范围内的铌元素能够进一步改善锂锰氧化物的晶体结构，使得暴露在外表面的锂锰氧化物的活性晶面(111)数量减小，即与电解液接触的活性晶面(111)的数量减少，从而减少电解液与锂锰氧化物表面的副反应，进一步减少Mn溶出，从而提高电化学装置的高温循环性能和存储容量保持性能。可以在锂锰氧化物改性过程中，通过加入含铌化合物并通过控制含铌化合物的添加量，从而控制铌元素在正极活性材料层中的含量。
在本申请的一种实施方案中，本申请的电化学装置满足条件(c)至(d)中的至少一者：(c)0.011﹤A+C≤2.8；(d)0.011≤A+B+C≤3.3；(e)0﹤C/B≤40。不限于任何理论，通过控制正极活性材料中铝元素与铌元素含量之和，即A+C的值在上述范围内，和/或，控制正极活性材料中铝元素、钠元素及铌元素含量之和，即A+B+C的值在上述范围内，和/或，控制正极活性材料中的铌元素含量与钠元素含量之比，即C/B的值在上述范围内，能够得到具有优良高温循环性能和存储容量保持性能的电化学装置。
在本申请的一种实施方案中，0.07≤A+C≤2.3。
通过控制正极活性材料中铝元素与铌元素含量之和，即A+C的值在上述范围内，能够得到更优的高温循环性能和存储容量保持性能。在本申请的一种实施方案中，采用X射线衍射(XRD)对本申请的正极极片粉末测试时，锂锰氧化物满足条件(f)至(g)中的至少一者：(f)锂锰氧化物在18°至20°处出现对应于(111)晶面的第一衍射峰，第一衍射 峰的峰强为I(111)；(g)锂锰氧化物在43°至45°处出现对应于(400)晶面的第二衍射峰，第二衍射峰的峰强为I(400)；(h)锂锰氧化物在63°至65°处出现对应于(440)晶面的第三衍射峰，第三衍射峰的峰强为I(440)。
在本申请的一种实施方案中，本申请的电化学装置满足条件(i)至(j)中的至少一者：(i)0.25﹤I(400)/I(111)﹤0.55；(j)0.35﹤I(440)/I(400)﹤0.55。
不限于任何理论，本申请的发明人发现，通过控制I(400)/I(111)在上述范围内，和/或控制I(440)/I(400)在上述范围内，能够进一步改善锂锰氧化物的晶体结构，使得暴露在外表面的锂锰氧化物的活性晶面(111)数量减小，从而减少电解液与锂锰氧化物表面的副反应，进一步减少Mn溶出，提高电化学装置的高温循环性能和存储容量保持性能。
在本申请的一种实施方案中，正极活性材料层还可以包含锂镍钴锰酸氧化物，基于所述正极活性材料重量，所述钴元素的重量百分含量为小于或等于15％。
本申请的正极活性材料层中还可以包含锂镍钴锰酸氧化物，锂镍钴锰酸氧化物表面的残碱(例如Li 2CO 3或LiOH)能够与电解液中的氢氟酸(HF)反应，降低电解液酸度，进一步减少Mn溶出，从而提高电化学装置的高温循环性能和存储容量保持性能。因此本申请中基于正极活性材料的重量，控制正极活性材料中钴的重量百分含量为小于或等于15％，能够在进一步提高电化学装置高温循环性能和存储容量保持性能的同时降低生产成本。
在本申请的一种实施方案中，正极活性材料层中镍元素与锰元素的摩尔比为0.02∶1至0.7∶1，钴元素与锰元素的摩尔比小于或等于0.3∶1。
通过控制正极活性材料层中镍元素与锰元素的摩尔比以及钴元素与锰元素的摩尔比在上述范围内，能够使正极活性材料层中的镍元素、锰元素和钴元素合理配置，从而得到具有优异高温循环性能和存储容量保持性能的电化学装置。
在本申请的一种实施方案中，正极活性材料层中还可以包含磷酸铁锂(LiFePO 4，即LFP)，其中磷酸铁锂的平均粒径小于锂锰氧化物的平均粒径。
不限于任何理论，由于磷酸铁锂粒径小，使得锂锰氧化物的至少部分表面上有磷酸铁锂，也即锂锰氧化物可以部分被磷酸铁锂包覆，也可以是全部包覆，从而抑制锂锰氧化物表面副反应，进一步改善电化学装置高温循环性能和存储容量保持性能。
在本申请的一种实施方案中，正极活性材料层中铁元素与锰元素的摩尔比为0.02∶1至0.25∶1。
通过控制正极活性材料层中铁元素与锰元素的摩尔比在上述范围内，能够使正极活性 材料层中的铁元素和锰元素合理配置，抑制锂锰氧化物表面副反应，从而进一步提高电化学装置高温循环性能和存储容量保持性能。
在本申请的一种实施方案中，以正极活性材料层的重量为基准，磷酸铁锂的重量百分含量为≤30％。
不限于任何理论，当磷酸铁锂的含量在正极活性材料层中过高时(例如高于30％，影响电化学装置的能量密度。通过控制正极活性材料层中磷酸铁锂的重量百分含量在上述范围内，能够在进一步提升电化学装置高温循环性能和存储容量保持性能的同时使电化学装置具有高的能量密度。
在本申请的一种实施方案中，正极活性材料层的压实密度P为2.7g/cm 3≤P≤4.0g/cm 3。不限于任何理论，当正极活性材料层的压实密度过低时(例如低于2.7g/cm 3)，不利于电化学装置能量密度的提升；当正极活性材料层的压实密度过高时(例如高于4.0g/cm 3)，正极更容易出现脆断，不利于电化学装置的安全性。通过控制正极活性材料层的压实密度在上述范围内，能够使电化学装置具有高能量密度的同时具有优良的安全性。
本申请提供了一种电化学装置及电子装置，该电化学装置的正极包括正极集流体和设置于正极集流体至少一个表面上的正极活性材料层，正极活性材料层包含锂锰氧化物，其中锂锰氧化物包含铝元素和钠元素，通过控制述正极活性材料中铝元素的含量A％和钠元素的含量B％满足0.01≤A≤2，0.001≤B≤1，能够改善锂锰氧化物的晶体结构，减少锰元素溶出，提高电化学装置的循环性能，尤其是高温条件下的循环性能，还能够提高电化学装置的高温储存性能。
附图说明
为了更清楚地说明本申请和现有技术的技术方案，下面对实施例和现有技术中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例。
图1为本申请实施例35的正极极片粉末的XRD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，以下参照附图和实施例，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技术方案，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电化学装置，包括正极，正极包括正极集流体和设置于正极集流体至少一个表面上的正极活性材料层，正极活性材料层包含锂锰氧化物，锂锰氧化物包含铝元素和钠元素，基于正极活性材料总重量，铝元素含量为A％，钠元素含量为B％，满足0.01≤A≤2，0.001≤B≤1。在本申请的一种实施方案中，0.49≤A≤1.8，0.001≤B﹤0.5。
本申请的正极活性材料层包含锂锰氧化物，锂锰氧化物包含铝元素和钠元素。通过控制铝元素和钠元素的含量在上述范围内能够减少锰(Mn)溶出，从而改善电化学装置的高温循环性能。不限于任何理论，这可能是由于上述含量范围的铝元素能够增强锂锰氧化物中Mn-O键的稳定性，改善锂锰氧化物的晶体结构，降低锰元素的姜泰勒(Jahn-Tellen)效应；钠元素作为杂质元素，当在上述含量范围内时几乎不会对电化学装置的高温循环性能产生影响。因此整体上本申请通过控制铝元素和钠元素的含量在上述范围内，能够减少Mn溶出，同时降低钠元素对正极性能的影响，从而改善电化学装置的循环性能和存储容量保持性能。
本申请的锂锰氧化物可以包括但不限于：改性LiMn 2O 4(下文简称改性LMO)。本申请对锂锰氧化物的改性方法没有特别限制，例如，可以在合成LiMn 2O 4的过程中加入含铝化合物，从而使本申请的锂锰氧化物中含有铝元素。
本申请的正极活性材料层可以设置在正极集流体的至少一个表面上，例如，正极活性材料层设置在正极集流体的一个表面上，或者，正极活性材料层设置在正极集流体的两个表面上。
在本申请的一种实施方案中，本申请的电化学装置满足条件(a)或(b)中的至少一者：(a)0.011≤A+B≤2.5；(b)0.1≤A/B≤125。在一些实施例中，A+B可以为0.011、0.03、0.05、0.07、0.1、0.3、0.5、0.9、1.0、1.1、1.3、1.5、1.7、1.9、2.0、2.5或为以上任意两个数值所组成的范围。在本申请的一种实施方案中，A/B可以为0.1、0.3、0.5、0.7、0.9、1.0、3.0、5.0、7.0、10、15、20、25、40、60、80、100、110、120、125或为以上任意两个数值所组成的范围。
不限于任何理论，本申请通过控制正极活性材料中的铝元素含量和钠元素含量之和，即A+B的值在上述范围内，和/或，控制正极活性材料中的铝元素含量与钠元素含量之比，即A/B的值在上述范围内，能够得到具有优良高温循环性能和存储容量保持性能的电化学 装置，当A/B过大时，对电化学装置的循环性能改善有限，当A/B的值过小时可能会影响电化学装置的可逆容量。
在本申请的一种实施方案中，锂锰氧化物进一步包含铌元素，基于正极活性材料的总重量，铌元素的含量为C％，满足0﹤C≤1。在一些实施例中，0.0001≤C≤0.7。在一些实施例中，0.0001≤C≤0.5。在一些实施例中，C可以为0.001、0.003、0.005、0.008、0.1、0.3、0.5、0.7、0.9、1.0或为以上任意两个数值所组成的范围。
不限于任何理论，本申请的发明人发现，上述含量范围内的铌元素能够进一步改善锂锰氧化物的晶体结构，使得暴露在外表面的锂锰氧化物的活性晶面(111)数量减小，即与电解液接触的活性晶面(111)的数量减少，从而减少电解液与锂锰氧化物表面的副反应，进一步减少Mn溶出，从而提高电化学装置的高温循环性能和存储容量保持性能。可以在锂锰氧化物改性过程中，通过加入含铌化合物并通过控制含铌化合物的添加量，从而控制铌元素在正极活性材料层中的含量。本申请对含铌化合物没有特别限制，例如可以包括但不限于：Nb 2O 5、NbF 5。
在本申请的一种实施方案中，本申请的电化学装置满足条件0.01﹤A+C≤2.8。在一些实施例中，0.011﹤A+C≤2。在一些实施例中，0.07≤A+C≤2.3。在一些实施例中，0.01﹤A+C≤1.6。在一些实施例中A+C可以为0.011、0.03、0.05、0.07、0.09、0.1、0.3、0.5、0.7、0.9、1.0、1.2、1.4、1.6、1.8、2.0、2.2、2.4、2.6、2.8或为以上任意两个数值所组成的范围。
通过控制正极活性材料中铝元素与铌元素含量之和，即A+C的值在上述范围内，电化学装置的性能处于较优状态，当A+C的值过高，对电化学装置循环性能提升有限，且可能会影响电化学装置可逆容量。
在本申请的一种实施方案中，本申请的电化学装置满足条件0.011≤A+B+C≤3.3在一些实施例中0.1≤A+B+C≤2.0。在一些实施例中A+B+C可以为0.011、0.05、0.07、0.1、0.3、0.5、0.7、0.9、1.0、1.2、1.4、1.6、1.8、2.0、2.5、3.0、3.3或为以上任意两个数值所组成的范围。
通过控制A+B+C的值在上述范围内，电化学装置具有较优的循环性能和存储性能。
在本申请的一种实施方案中，本申请的电化学装置满足条件0＜C/B≤40。在一些实施例中，0﹤C/B≤10。在一些实施例中，0﹤C/B≤5。在一些实施例中，0＜C/B≤3。在一些实施例中，C/B可以为0.0001、0.0005、0.001、0.003、0.005、0.007、0.009、0.01、0.03、0.05、 0.07、0.09、0.1、0.3、0.5、0.7、0.9、1.0、1.2、1.5、1.7、1.9、2.0、3.0、5.0、7.0、9.0、10.0、15、20、25、30、35、40或为以上任意两个数值所组成的范围。
通过控制C/B的值在上述范围内，能够得到具有优良高温循环性能和存储容量保持性能的电化学装置，当C/B的值过高时，可能会影响电化学装置的循环性能，当C/B的值过低时，对锂锰氧化物活性晶面(111)的保护较小，对Mn溶出的抑制有限，且可能会使电化学装置可逆容量的损失增大。
在本申请的一种实施方案中，采用X射线衍射(XRD)对本申请的正极极片粉末测试时，锂锰氧化物在18°至20°处出现对应于(111)晶面的第一衍射峰，第一衍射峰的峰强为I(111)。
在本申请的一种实施方案中，采用X射线衍射(XRD)对本申请的正极极片粉末测试时，锂锰氧化物在43°至45°处出现对应于(400)晶面的第二衍射峰，第二衍射峰的峰强为I(400)。
在本申请的一种实施方案中，采用X射线衍射(XRD)对本申请的正极极片粉末测试时，锂锰氧化物在63°至65°处出现对应于(440)晶面的第三衍射峰，第三衍射峰的峰强为I(440)。
本申请的正极极片包括正极活性材料层，正极活性材料层中包含正极活性材料，正极活性材料主要成分为锂锰氧化物，通过XRD测试表明，本申请的锂锰氧化物中包含(111)晶面、(400)晶面以及(440)晶面。
在本申请的一种实施方案中，本申请的电化学装置满足0.25﹤I(400)/I(111)﹤0.55。
在本申请的一种实施方案中，本申请的电化学装置满足0.35﹤I(440)/I(400)﹤0.55。
不限于任何理论，通过控制I(400)/I(111)在上述范围内，和/或控制I(440)/I(400)在上述范围内，能够进一步改善锂锰氧化物的晶体结构，使得暴露在外表面的锂锰氧化物的活性晶面(111)数量减小，从而减少电解液与锂锰氧化物表面的副反应，进一步减少Mn溶出，提高电化学装置的高温循环性能和存储容量保持性能。
在本申请的一种实施方案中，正极活性材料还包含M元素，M元素包含Cu、Fe、Mg、Ti、Zr、Zn、W、Sr、Y中的至少一种。在一些实施例中M元素可以包含Mg，且包含Cu、Fe、Ti、Zr、Zn、W、Sr、Y中的至少一种。
在本申请的一种实施方案中，基于正极活性材料重量，M元素的含量小于或等于5％。在一些实施例中M元素的含量可以为0.01％、0.03％、0.05％、0.07％、0.1％、0.3％、0.5％、 0.7％、1.0％、2.0％、3.0％、5.0％或为以上任意两个数值所组成的范围。
在本申请的一种实施方案中，正极活性材料还包含X元素，X元素包含S、P、B、F、或Cl中的至少一种。
在本申请的一种实施方案中，基于正极活性材料重量，X元素的含量小于或等于3％。在一些实施例中X元素的含量可以为0.01％、0.03％、0.05％、0.07％、0.1％、0.3％、0.5％、0.7％、1.0％、2.0％、3.0％或为以上任意两个数值所组成的范围。
在本申请的一种实施方案中，正极活性材料层还可以包含锂镍钴锰酸氧化物，基于正极活性材料重量，钴的重量百分含量为小于或等于15％。
不限于任何理论，本申请的正极活性材料层中还可以包含锂镍钴锰酸氧化物，锂镍钴锰酸氧化物表面的残碱(例如Li 2CO 3或LiOH)能够与电解液中的氢氟酸(HF)反应，降低电解液酸度，进一步减少Mn溶出，从而提高电化学装置的高温循环性能和存储容量保持性能。当钴的含量过高时，会导致电化学装置的生产成本上升。因此本申请中基于正极活性材料的重量，控制锂镍钴锰酸氧化物中钴的重量百分含量为小于或等于15％，能够在进一步提高电化学装置高温循环性能和存储容量保持性能的同时降低生产成本。
本申请对锂镍钴锰酸氧化物没有特别限制，只要能够实现本申请目的即可，例如锂镍钴锰酸氧化物可以为镍钴锰酸锂(下文简称NCM)。该镍钴锰酸锂可以为单晶镍钴锰酸锂或多晶镍钴锰酸锂。
在本申请的一种实施方案中，正极活性材料层中镍元素与锰元素的摩尔比为0.02∶1至0.7∶1。
在本申请的一种实施方案中，正极活性材料层中钴元素与锰元素的摩尔比小于等于0.3∶1。
本申请中，通过控制正极活性材料层中镍元素与锰元素的摩尔比以及钴元素与锰元素的摩尔比在上述范围内，能够使正极活性材料层中的镍元素、锰元素和钴元素合理配置，从而得到具有优异高温循环性能和存储容量保持性能的电化学装置。
在本申请的一种实施方案中，正极活性材料层中还可以包含磷酸铁锂(LiFePO 4，即LFP)，其中磷酸铁锂的平均粒径小于锂锰氧化物的平均粒径。
在本申请的一种实施方案中，磷酸铁锂的平均粒径小于或等于2μm。在一些实施例中，磷酸铁锂的平均粒径小于或等于1.8μm。在一些实施例中，磷酸铁锂的平均粒径小于或等于1.5μm。在一些实施例中，磷酸铁锂的平均粒径小于等于1.2μm。在一些实施例中，磷 酸铁锂的平均粒径小于或等于1.0μm。
本申请的一种实施方案利用磷酸铁锂小粒径的特点，使得锂锰氧化物的至少部分表面有磷酸铁锂，也即锂锰氧化物可以部分被磷酸铁锂包覆，也可以是全部包覆，从而抑制锂锰氧化物表面副反应，进一步改善电化学装置高温循环性能和存储容量保持性能。
在本申请的一种实施方案中，正极活性材料层中铁元素与锰元素的摩尔比为0.02∶1至0.25∶1。在一些实施例中，正极活性材料层中铁元素与锰元素的摩尔比为0.03∶1至0.13∶1。在一些实施例中，正极活性材料层中铁元素与锰元素的摩尔比为0.05∶1至0.12∶1。在一些实施例中，正极活性材料层中铁元素与锰元素的摩尔比为0.03∶1至0.13∶1。
通过控制正极活性材料层中铁元素与锰元素的摩尔比在上述范围内，能够使正极活性材料层中的铁元素和锰元素合理配置，抑制锂锰氧化物表面副反应，从而进一步提高电化学装置高温循环性能和存储容量保持性能。
在本申请的一种实施方案中，以正极活性材料层的重量为基准，磷酸铁锂的重量百分含量为≤30％。
不限于任何理论，当磷酸铁锂的含量在正极活性材料层中过高时(例如高于30％)，影响电化学装置的能量密度。通过控制正极活性材料层中磷酸铁锂的重量百分含量在上述范围内，能够在进一步提升电化学装置高温循环性能和存储容量保持性能的同时使电化学装置具有高的能量密度。
在本申请的一种实施方案中，正极活性材料层的压实密度P为2.7g/cm 3≤P≤4.0g/cm 3。不限于任何理论，当正极活性材料层的压实密度过低时(例如低于2.7g/cm 3)，不利于电化学装置能量密度的提升；当正极活性材料层的压实密度过高时(例如高于4.0g/cm 3)，正极更容易出现脆断，不利于电化学装置的安全性。通过控制正极活性材料层的压实密度在上述范围内，能够使电化学装置具有高能量密度的同时具有优良的安全性。
本申请对锂锰氧化物的制备方法没有特别限制，可以采用本领域技术人员公知的制备方法，例如，可以在合成锂锰氧化物过程中，在LiMn 2O 4中加入含铝化合物(例如Al 2O 3、Al(OH) 3、AlF 3)得到上述锂锰氧化物，即改性LMO。另外，本申请可以通过调整锂锰氧化物中铝元素的含量，例如控制含铝化合物的加入量，即可实现正极活性材料层中铝元素的变化；通过调整LiMn 2O 4的前驱体中钠元素的含量，即可实现正极活性材料层中钠元素含量的变化，本申请对其调整过程不做具体限定，只要能实现本申请目的即可。
本申请中的正极极片没有特别限制，只要能够实现本申请目的即可。例如，正极极片 通常包含正极集流体和正极活性材料层。其中，正极集流体没有特别限制，可以为本领域的任何正极集流体，例如铝箔、铝合金箔或复合集流体等。
本申请中的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，负极极片通常包含负极集流体和负极活性材料层。其中，负极集流体没有特别限制，可以使用金属箔材或多孔金属板等材料，例如铜、镍、钛或铁等金属或它们的合金的箔材或多孔板，如铜箔。负极活性材料层包括负极活性材料、导电剂、粘结剂和增稠剂。负极活性材料没有特别限制，可以使用本领域的任何负极活性材料。例如，可以包括人造石墨、天然石墨、中间相碳微球(MCMB)、软碳、硬碳、硅、硅碳、SiO、Li-Sn合金、Li-Sn-O合金、Sn、SnO、SnO 2、尖晶石结构的钛酸锂Li 4Ti 5O 12、Li-Al合金或金属锂中的至少一种；导电剂可以是石墨、超导碳、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种；粘结剂可以是丁苯橡胶(SBR)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚乙烯醇缩丁醛(PVB)、水性丙烯酸树脂(water-basedacrylic resin)或羧甲基纤维素(CMC)中的至少一种；增稠剂可以是羧甲基纤维素(CMC)。
本申请的隔离膜的基材包括但不限于，选自聚乙烯(PE)、聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚酰亚胺(PI)或芳纶中的至少一种。举例来说，聚乙烯包括选自高密度聚乙烯、低密度聚乙烯和超高分子量聚乙烯中的至少一种组分。尤其是聚乙烯和聚丙烯，它们对防止短路具有优良的作用，并可以通过关断效应改善电化学装置的稳定性。基材可以是单层结构或多种混合的多层复合结构，厚度为3μm至20μm。
本申请的锂离子电池还包括电解质，电解质可以是凝胶电解质、固态电解质和电解液中的一种或多种，电解液包括锂盐和非水溶剂。在本申请一些实施方案中，锂盐选自LiPF 6、LiBF 4、LiAsF 6、LiClO 4、LiB(C 6H 5) 4、LiCH 3SO 3、LiCF 3SO 3、LiN(SO 2CF 3) 2、LiC(SO 2CF 3) 3、LiSiF 6、LiBOB和二氟硼酸锂中的一种或多种。举例来说，锂盐可以选用LiPF 6，因为它可以给出高的离子导电率并改善循环特性。非水溶剂可为碳酸酯化合物、羧酸酯化合物、醚化合物、其它有机溶剂或它们的组合。上述碳酸酯化合物可为链状碳酸酯化合物、环状碳酸酯化合物、氟代碳酸酯化合物或其组合。上述链状碳酸酯化合物的实例为碳酸二甲酯(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)、碳酸甲乙酯(MEC)及其组合。环状碳酸酯化合物的实例为碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)、碳酸乙烯基亚乙酯(VEC)及其组合。氟代碳酸酯化合物的实例为碳酸氟代亚乙酯(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、碳酸三氟甲基亚乙酯及其组合。上述羧酸酯化合物的实例为甲酸甲酯、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、甲瓦龙酸内酯、己内酯及其组合。上述醚化合物的实例为二丁醚、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、乙氧基甲氧基乙烷、2-甲基四氢呋喃、四氢呋喃及其组合。上述其它有机溶剂的实例为二甲亚砜、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、甲酰胺、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯、磷酸三辛酯、和磷酸酯及其组合。
本申请的第二方面提供了一种电子装置，包含本申请上述实施方案中所述的电化学装置。
本申请的电子装置没有特别限定，其可以是用于现有技术中已知的任何电子装置。在一些实施例中，电子装置可以包括，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、家庭用大型蓄电池和锂离子电容器等。
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。例如锂离子电池可以通过以下过程制造：将正极和负极经由隔离膜重叠，并根据需要将其卷绕、折叠等操作后放入壳体内，将电解液注入壳体并封口。此外，也可以根据需要将防过电流元件、导板等置于壳体中，从而防止锂离子电池内部的压力上升、过充放电。
本申请提供了一种电化学装置及电子装置，该电化学装置的正极包括正极集流体和设置于正极集流体至少一个表面上的正极活性材料层，正极活性材料层包含锂锰氧化物，其中锂锰氧化物包含铝元素和钠元素，通过控制述正极活性材料中铝元素的含量A％和钠元素的含量B％满足0.01≤A≤2，0.001≤B≤1，能够改善锂锰氧化物的晶体结构，减少锰元素溶出，提高电化学装置的循环性能，尤其是高温条件下的循环性能，还能够提高电化学装置的高温储存性能。
测试方法和设备：
正极活性材料层元素含量测试：
将放电至电压为2.8V的锂离子电池进行拆解，然后将烘干后的正极极片上的正极活性材料层用混合溶剂溶解(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(Inductively coupled plasma，电感耦合等离子)分析仪测试溶液中Al、Na、Nb等元素的含量。
XRD测试：
将放电至电压为2.8V的锂离子电池进行拆解，然后取出正极极片，用刮刀将正极活性材料层刮下，得到正极活性材料层粉末，然后将正极活性材料层粉末放置在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XRD衍射图。在XRD衍射图中取锂锰氧化物的特征峰(111)、(400)、(440)对应的峰值，然后得到I(400)和I(111)的比值，记为I(400)/I(111)；I(440)和I(400)的比值，记为I(440)/I(400)。
正极活性材料层中颗粒粒径测试：
将放电至电压为2.8V的锂离子电池进行拆解，然后将烘干后的正极极片进行切片，然后使用扫描电子显微镜(SEM)观察切片截面，寻找截面中的颗粒，然后使用能谱仪(EDS)确定单颗粒的成分，使用SEM测量单颗粒粒径大小，测量时放大倍数为1000倍，选取三张图片，计算平均值。其中测试仪器为OXFORD EDS(X-max-20mm 2)。
正极活性材料层压实密度测试：
将放电至电压为2.8V的锂离子电池进行拆解，然后取出正极极片，将正极极片浸泡在DMC(碳酸二甲酯)中30min，去除正极极片表面的电解液及副产物，然后在通风橱中干燥4小时，取出干燥后的正极极片，选择5cm×5cm大小的正极极片5片，通过万分尺分别测量正极极片的厚度，记为d0；用刮刀刮下正极极片中正极活性材料层，通过天平称量正极活性材料层的重量，记为m，通过万分尺测量去除活性物质的集流体厚度记为d，按照下式计算正极活性材料层的压实密度：
压实密度P＝m/[5cm×5cm×(d0-d)]，单位g/cm 3。
正极活性材料层的压实密度为5片正极极片的平均值。
锂离子电池容量测试：
取4个锂离子电池，在25℃的环境中，在0.5C的充电电流下进行充电，直到上限电压为4.2V，然后在0.2C的放电电流下进行恒流放电，直到最终电压为2.8V，计算0.2C首次的放电容量作为该锂离子电池的容量。
锂离子电池循环性能测试：
通过以下步骤对锂离子电池重复进行充电和放电，并计算锂离子电池的放电容量保持率：
在25℃的环境中，进行第一次充电和放电，在0.5C的充电电流下进行充电，直到电压为4.2V，然后在1C的放电电流下进行恒流放电，直到最终电压为2.8V，记录放电容量，记为首次循环的放电容量；而后重复上述步骤进行1000次的充电和放电循环，记录第1000次循环的放电容量。
25℃循环容量保持率＝(第1000次循环的放电容量/首次循环的放电容量)×100％。
在45℃的环境中，在0.5C的充电电流下进行充电，直到电压为4.2V，然后在1C的放电电流下进行恒流放电，直到最终电压为2.8V，记录放电容量，记为首次循环的放电容量；而后重复上述步骤进行500次的充电和放电循环，记录第500次循环的放电容量。
45℃循环容量保持率＝(第500次循环的放电容量/首次循环的放电容量)×100％。
锂离子电池高温存储性能测试：
在25℃的环境中，在0.5C的充电电流下进行充电，直到上限电压为4.2V，然后在1C的放电电流下进行恒流放电，直到最终电压为2.8V，记录放电容量，记为存储前容量；
以0.5C倍率恒定电流充电至电压3.85V，在4.2V恒定电压下充电至电流低于0.05C，将电池置于60℃烘箱存储14天后，在1C的放电电流下进行恒流放电，直到最终电压为2.8V；然后在0.5C的充电电流下进行充电，直到电压为4.2V，然后在1C的放电电流下进行恒流放电，直到电压为2.8V，记录电池放电容量，记为存储后容量。
锂离子电池的容量保持率＝存储后容量/存储前容量×100％。
实施例1
<锂锰氧化物的制备>
称取碳酸锂203.3g(其中锂元素含量为18.71％)、二氧化锰1000.0g(其中Mn元素含量为60.22％，Na元素含量为0.27％)，三氧化二铝29.96g(铝元素含量52.91％)，在高速混合机中300r/min混合20min，将混合物置于空气窑炉中，以5℃/min升温至820℃，保持24h，自然冷却后取出，过300目筛后得到锂锰氧化物(即改性LMO)。
<正极极片的制备>
将制得的正极活性材料、粘结剂聚偏氟乙烯(PVDF)、导电炭黑、碳纳米管(CNT)按重量比95∶2∶1.8∶1.2混合，然后加入NMP(N-甲基吡咯烷酮)作为溶剂，在真空搅拌下调配成均一透明状、固含量为75％的正极浆料。将正极浆料均匀涂布在厚度为9μm的铝箔的一个表面上，90℃条件下烘干，冷压后得到正极活性材料层总厚度为100μm的正极极片，然后在该正极极片的另一个表面上重复以上步骤，得到双面涂布有正极活性材料层的正极极片。将正极极片裁切成74mm×867mm的规格并焊接极耳后待用。其中，正极活性材料层中的铝元素含量为1.52％，钠元素含量为0.26％，正极活性材料层的压实密度为2.8g/cm 3。
<负极极片的制备>
将负极活性材料人造石墨、丁苯橡胶(SBR)及羧甲基纤维素(CMC)按重量比98∶1∶1混合，然后加入去离子水作为溶剂，调配成固含量为70％的浆料，并搅拌均匀。将浆料均匀涂布在厚度为8μm的铜箔的一个表面上，110℃条件下烘干，冷压后得到负极活性材料层厚度为150μm的单面涂布负极活性材料层的负极极片，然后在该负极极片的另一个表面上重复以上涂布步骤，得到双面涂布有负极活性材料层的负极极片。将负极极片裁切成74mm×867mm的规格并焊接极耳后待用。
<隔离膜的制备>
以厚度为15μm的聚乙烯(PE)多孔聚合薄膜作为隔离膜。
<电解液的制备>
在含水量小于10ppm的环境下，将非水有机溶剂碳酸丙烯酯(PC)，碳酸乙烯酯(EC)，碳酸二乙酯(DEC)按照重量比1∶1∶1混合，然后向非水有机溶剂中加入六氟磷酸锂(LiPF 6)溶解并混合均匀。其中，LiPF 6在电解液中的摩尔浓度为1.15mol/L。基于电解液总重量，加入2％的氟代碳酸乙烯酯，2％的碳酸亚乙烯酯，1％的硫酸乙烯酯，混合均匀 制成电解液。
<锂离子电池的制备>
将上述制备的正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正极极片和负极极片中间起到隔离的作用，并卷绕得到电极组件。将电极组件装入铝塑膜包装袋中，并在80℃下脱去水分，注入配好的电解液，经过真空封装、静置、化成、整形等工序得到锂离子电池。
实施例2至实施例7
与实施例1制备方法相似，不同之处在于表1所示元素含量及锂锰氧化物粒径。
实施例8
与实施例1制备方法相似，不同之处在于用850.3g的四氧化三锰替代1000.0g的二氧化锰，其他参数不同之处见表1。
实施例9
与实施例1制备方法相似，不同之处在于在锂锰氧化物中添加含铌化合物Nb 2O 5，调整正极活性材料层中的铝元素含量为1.01％、钠元素含量为0.26％、铌元素含量为0.09％，调整正极活性材料层的压实密度为3.0g/cm 3，除此以外，与实施例1相同。
实施例10
与实施例9制备方法相似，不同之处在于表1所示元素含量及锂锰氧化物粒径。
实施例11
称取碳酸锂203.3g(其中锂元素含量为18.71％)、四氧化三锰850.3g(其中Mn元素含量为70.82％，Na元素含量为0.01％)，三氧化二铝19.10g(铝元素含量52.91％)，五氧化二铌2.87g(铌元素含量79.46％)在高速混合机中300r/min混合20min，将混合物置于空气窑炉中，以5℃/min升温至750℃，保持24h，自然冷却后取出，过300目筛后即为锂锰氧化物(即改性LMO)成品。
实施例12至实施例13
与实施例11的制备方法相似，不同之处在于表1所示元素含量以及锂锰氧化物的粒径。
实施例14至实施例21
与实施例9的制备方法相似，不同之处在于表1所示元素含量及锂锰氧化物粒径。
实施例22
将正极活性材料改性LMO(其制备方法与实施例9相似，不同之处在于表1所示元素 含量和粒径)与平均粒径为15.3μm的多晶锂镍钴锰酸氧化物(LiNi 0.60Co 0.10Mn 0.30O 2，记做NCM:15.8(601030))进行混合，得到混合物，按照表1中所示的参数进行配比，使得镍和锰的摩尔比、钴和锰的摩尔比满足表1所示比例，正极活性材料层中的元素含量及粒径如表1所示，正极活性材料层的压实密度为3.3g/cm 3，除此以外，与实施例9相同。
实施例23至实施例33
与实施例22的制备方法相似，不同之处在于如表1所示调整元素含量、改性LMO平均粒径、多晶锂镍钴锰酸氧化物的种类及平均粒径、镍和锰的摩尔比、钴和锰的摩尔比等参数。
实施例34
将正极活性材料改性LMO(其制备方法与实施例11相似，不同之处在于表1所示元素含量和粒径)与平均粒径为15.3μm的多晶锂镍钴锰酸氧化物(LiNi 0.50Co 0.20Mn 0.30O 2，记做NCM:15.9(502030))进行混合，得到混合物。调整LMO与NCM的比例使得镍和锰的摩尔比、钴和锰的摩尔比满足表1所示比例。正极活性材料层中的元素含量及粒径如表1所示。除此以外，与实施例11相同。
实施例35
将正极活性材料改性LMO(其制备方法与实施例11相似，不同之处在于表1所示元素含量和粒径)与平均粒径为1μm的磷酸铁锂(简写为LFP)进行混合，得到混合物。调整LMO与LFP的比例使得铁和锰的摩尔比满足表1所示比例。正极活性材料层中的元素含量及粒径如表1所示。除此以外，与实施例11相同。
实施例36
与实施例35制备方法相似，不同之处在于表1所示参数。
实施例37
将正极活性材料改性LMO(其制备方法与实施例9相似，不同之处在于表1所示元素含量和粒径)、平均粒径为16.2μm的多晶锂镍钴锰酸氧化物(LiNi 0.55Co 0.15Mn 0.30O 2，记做NCM:16.2(551530))和平均粒径为1μm的磷酸铁锂(简写为LFP)进行混合，得到混合物，使得镍和锰的摩尔比、钴和锰的摩尔比满足表1所示比例，正极活性材料层中的元素含量及粒径如表1所示，正极活性材料层的压实密度为3.3g/cm 3。除此以外，与实施例9相同。
实施例38
将正极活性材料改性LMO(其制备方法与实施例11相似，不同之处在于表1所示元素含量和粒径)、平均粒径为6.4μm的单晶锂镍钴锰酸氧化物(LiNi 0.55Co 0.15Mn 0.30O 2，记做NCM:6.4(551530))和平均粒径为1μm的磷酸铁锂(简写为LFP)进行混合，得到混合物，使得镍和锰的摩尔比、钴和锰的摩尔比满足表1所示比例。除此以外，与实施例11相同。
实施例39
将正极活性材料改性LMO(其制备方法与实施例9相似，不同之处在于表1所示元素含量和粒径)、平均粒径为16.2μm的多晶锂镍钴锰酸氧化物(LiNi 0.55Co 0.15Mn 0.30O 2，记做NCM:16.2(551530))和粒径为1μm的磷酸铁锂(简写为LFP)进行混合，得到混合物，使得镍和锰的摩尔比、钴和锰的摩尔比满足表1所示比例。除此以外，其余与实施例9相同。
实施例40至实施例41
制备方法与实施例39类似，不同之处在于表1所示参数。
对比例1
除了正极活性材料为未掺杂铝元素的LiMn 2O 4以外，其余与实施例1相同。
对比例2
除了正极活性材料为未掺杂铝元素的LiMn 2O 4以外，其余与实施例22相同。
对比例3
除了正极活性材料为未掺杂铝元素的LiMn 2O 4以外，其余与实施例37相同。
对比例4
除了如表1所示调整正极活性材料的元素含量以外，其余与实施例9相同。
对比例5
除了如表1所示调整正极活性材料的元素含量以外，其余与实施例9相同。
表1
Figure PCTCN2021112091-appb-000001
Figure PCTCN2021112091-appb-000002
Figure PCTCN2021112091-appb-000003
Figure PCTCN2021112091-appb-000004
其中A、B、C之间组合的参数如表2表所示：
表2
Figure PCTCN2021112091-appb-000005
Figure PCTCN2021112091-appb-000006
Figure PCTCN2021112091-appb-000007
表1和表2中，“/”表示不含有或未测得。
从实施例1至8和对比例1可以看出，正极活性材料层中具有本申请铝元素含量A％及钠元素含量B％的锂离子电池，且0.01≤A≤2，0.001≤B≤1时，其25℃循环容量保持率、45℃循环容量保持率和存储容量保持率均明显提升，表明本申请的锂离子电池具有优异的循环性能，尤其是高温循环性能，以及优异的高温存储性能。
从实施例1至8和对比例1至3可以看出，当正极活性材料中不含有本申请的锂锰氧化物时(例如对比例1至3)，其I(400)/I(111)与I(440)/I(400)超出本申请范围。而具有本申请I(400)/I(111)、I(440)/I(400)范围的锂离子电池，具有优异的循环性能，尤其是高温循环性能，以及优异的高温存储性能。
从实施例9至21和对比例4至5可以看出，当正极活性材料中的铝元素含量过高时(例如对比例4)、钠元素含量过高时(例如对比例5)，其I(400)/I(111)与I(440)/I(400)超出本申请范围。而具有本申请铝元素及钠元素含量范围的锂离子电池，其25℃循环容量保持率、45℃循环容量保持率和存储容量保持率均明显提升。
从实施例1至8与实施例9至21对比可以看出，正极活性材料层中进一步包含本申请铌元素，且含量C％在本申请范围内时，锂离子电池的高温存储性能进一步得到提升。
从实施例9至21与实施例22至34对比可以看出，正极活性材料层中进一步含有锂镍钴锰酸氧化物时，锂离子电池的25℃循环容量保持率、45℃循环容量保持率和存储容量保持率进一步得到提升。
从实施例22至34可以看出，锂镍钴锰酸氧化物中钴的重量百分含量不同，对锂离子电池的循环性能和高温存储性能产生影响，但只要使得锂镍钴锰酸氧化物的含量在本申请范围内，就能够得到循环性能、高温存储性能优异的锂离子电池。
从实施例37至实施例41可以看出，正极活性材料层中进一步含有磷酸铁锂时，锂离子电池的25℃循环容量保持率、45℃循环容量保持率和存储容量保持率得到进一步提升。
铝元素含量、钠元素含量及铌元素含量间的关系，即A+B值、A/B值、A+C值、A+B+C值、C/B值通常也会影响锂离子电池的循环性能和高温存储性能，从实施例1至41还可以看出，只要使得上述A、B、C之间组合的参数在本申请范围内，就能够得到循环性能、高温存储性能优异的锂离子电池。
改性LMO的粒径、NCM的粒径、LFP的粒径、Co在正极活性材料层中的含量、Ni与Mn的摩尔比、Co与Mn的摩尔比、Fe与Mn的摩尔比以及正极活性材料层的压实密度通常也会影响锂离子电池的循环性能和高温存储性能，从实施例1至41还可以看出，只 要使得上述参数在本申请范围内，就能够得到循环性能、高温存储性能优异的锂离子电池。
图1为本申请实施例35的正极极片粉末的XRD图，从图1可以看出，本申请的正极活性材料在18°至20°处出现对应于(111)晶面的第一衍射峰，在43°至45°处出现对应于(400)晶面的第二衍射峰，在63°至65°处出现对应于(440)晶面的第三衍射峰，满足0.25﹤I(400)/I(111)﹤0.5，0.35﹤I(440)/I(400)﹤0.55。
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 (15)

  1. 一种电化学装置，其包括正极、负极、隔离膜和电解液，所述正极包括正极集流体和设置于所述正极集流体至少一个表面上的正极活性材料层，所述正极活性材料层包含锂锰氧化物，所述锂锰氧化物包含铝元素和钠元素，基于所述正极活性材料重量，所述铝元素含量为A％，所述钠元素含量为B％，满足0.01≤A≤2，0.001≤B≤1。
  2. 根据权利要求1所述的电化学装置，其中满足条件(a)或(b)中至少一者：
    (a)0.011≤A+B≤2.5；
    (b)0.1≤A/B≤125。
  3. 根据权利要求1所述的电化学装置，其中0.03≤A+B＜2，2＜A/B≤125。
  4. 根据权利要求1所述的电化学装置，其中进一步包含铌元素，基于所述正极活性材料重量，所述铌元素的含量为C％，满足0＜C≤1。
  5. 根据权利要求4所述的电化学装置，其中满足条件(c)至(d)中的至少一者：
    (c)0.011﹤A+C≤2.8；
    (d)0.011≤A+B+C≤3.3；
    (e)0﹤C/B≤40。
  6. 根据权利要求4所述的电化学装置，其中0.07≤A+C≤2.3。
  7. 根据权利要求1所述的电化学装置，其中，采用XRD测试，所述锂锰氧化物满足条件(f)至(g)中的至少一者：
    (f)所述锂锰氧化物在18°至20°处出现对应于(111)晶面的第一衍射峰，所述第一衍射峰的峰强为I(111)；
    (g)所述锂锰氧化物在43°至45°处出现对应于(400)晶面的第二衍射峰，所述第二衍射峰的峰强为I(400)；
    (h)所述锂锰氧化物在63°至65°处出现对应于(440)晶面的第三衍射峰，所述第三衍射峰的峰强为I(440)。
  8. 根据权利要求7所述的电化学装置，满足条件(i)至(j)中的至少一者：
    (i)0.25﹤I(400)/I(111)﹤0.55；
    (j)0.35﹤I(440)/I(400)﹤0.55。
  9. 根据权利要求1所述的电化学装置，其中，所述正极活性材料层还包含锂镍钴锰酸氧化物，所述锂镍钴锰酸氧化物中钴的重量百分含量为小于或等于15％。
  10. 根据权利要求9所述的电化学装置，其中，所述正极活性材料层中镍元素与锰元素的摩尔比为0.02∶1至0.7∶1，钴元素与锰元素的摩尔比小于或等于0.3∶1。
  11. 根据权利要求1-10任一项所述的电化学装置，其中，所述正极活性材料层中还包含磷酸铁锂，其中所述磷酸铁锂的平均粒径小于所述锂锰氧化物的平均粒径。
  12. 根据权利要求11所述的电化学装置，其中，所述正极活性材料层中铁元素与锰元素的摩尔比为0.02∶1至0.25∶1。
  13. 根据权利要求11所述的电化学装置，其中，以正极活性材料层的重量为基准，磷酸铁锂的重量百分含量为≤30％。
  14. 根据权利要求1所述的电化学装置，其中，所述正极活性材料层的压实密度P为2.7g/cm 3≤P≤4.0g/cm 3。
  15. 一种电子装置，其包含权利要求1至14任一项所述的电化学装置。
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