WO2023142029A1 - 一种正极活性材料、包含该正极活性材料的电化学装置和电子装置 - Google Patents

一种正极活性材料、包含该正极活性材料的电化学装置和电子装置 Download PDF

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WO2023142029A1
WO2023142029A1 PCT/CN2022/074938 CN2022074938W WO2023142029A1 WO 2023142029 A1 WO2023142029 A1 WO 2023142029A1 CN 2022074938 W CN2022074938 W CN 2022074938W WO 2023142029 A1 WO2023142029 A1 WO 2023142029A1
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positive electrode
active material
electrode active
molar ratio
region
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PCT/CN2022/074938
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English (en)
French (fr)
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刘文元
郎野
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东莞新能源科技有限公司
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Priority to CN202280003883.4A priority Critical patent/CN115606019A/zh
Priority to PCT/CN2022/074938 priority patent/WO2023142029A1/zh
Publication of WO2023142029A1 publication Critical patent/WO2023142029A1/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
    • H01M4/366—Composites as layered products
    • 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
    • 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 electrochemistry, in particular to a positive electrode active material, an electrochemical device and an electronic device containing the positive electrode active material.
  • lithium-ion batteries Due to its high energy density, long cycle life and no memory effect, lithium-ion batteries are widely used in wearable devices, smart phones, unmanned aerial vehicles, electric vehicles and large-scale energy storage equipment. It is a new type of green chemical power source with development potential, but it also puts forward higher requirements for the comprehensive performance of lithium-ion batteries.
  • the positive electrode active material in lithium-ion batteries is an important parameter that affects the performance of lithium-ion batteries.
  • the positive electrode active material lithium manganese oxide is widely used in lithium-ion batteries, but the Mn 3+ present in lithium manganate is prone to disproportionation. It leads to the dissolution of Mn 2+ , and then migrates to the negative electrode through the electrolyte, destroying the solid electrolyte interface (SEI), resulting in the loss of active lithium, thereby deteriorating the cycle performance of lithium-ion batteries.
  • SEI solid electrolyte interface
  • the improvement of Mn 2+ dissolution is often accompanied by the attenuation of the specific capacity of the positive electrode, and the deterioration of the cycle performance or storage performance of the electrochemical device, resulting in a decline in the overall performance of the electrochemical device.
  • the purpose of the present application is to provide a positive electrode active material, an electrochemical device and an electronic device containing the positive electrode active material, so as to improve the comprehensive performance of the electrochemical device.
  • the first aspect of the present application provides a positive electrode active material, including Mn element and Al element, and the positive electrode active material particle includes a first region close to the surface of the positive electrode active material particle and a second region away from the surface of the positive electrode active material particle , the molar ratio of Al/Mn in the first region is a1, and the molar ratio of Al/Mn in the second region is a2, satisfying 1.1 ⁇ a1/a2 ⁇ 100, preferably 5 ⁇ a1/a2 ⁇ 90.
  • the value of a1/a2 may be 1.1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or any range therebetween.
  • the first area refers to the part of the positive active material particles that is washed with 2.4mol/L sulfuric acid for 6 hours and is dissolved
  • the second area refers to the part that is not dissolved after the positive active material particles are washed with 2.4mol/L sulfuric acid for 6 hours. part.
  • the inventors of the present application have found that by regulating the ratio a1/a2 of the molar ratio a1 of Al/Mn in the first region to the molar ratio a2 of Al/Mn in the second region within the above-mentioned range, the Al in the positive electrode active material is rich Collected in the area close to the surface of the positive electrode active material, it can not only effectively improve the manganese dissolution phenomenon of the positive electrode to improve the cycle performance and storage performance of the electrochemical device, but also reduce the total content of Al in the positive electrode active material so that the positive electrode maintains a high specific capacity, thereby improving the overall performance of the electrochemical device.
  • a1/a2 when the value of a1/a2 is too small (for example, less than 1.1), it means that the molar ratio of Al/Mn in the first region and the second region is equivalent, or the molar ratio of Al/Mn in the first region is smaller than that in the second region, That is, the Al in the positive electrode active material is mainly concentrated in the inside of the positive electrode active material particles, so that the improvement of the manganese dissolution phenomenon of the positive electrode is not obvious, which is not conducive to improving the cycle performance and storage performance of the electrochemical device.
  • the Al in the obtained cathode active material is mainly enriched on the surface of the cathode active material particles, which is beneficial to improve the dissolution of cathode manganese while maintaining the specific capacity of the cathode.
  • the value of a1/a2 is too large (for example, greater than 100), that is, the molar ratio a1 of Al/Mn in the first region is too large, resulting in an increase in the total Al content in the positive electrode active material, which will reduce the specific capacity of the positive electrode .
  • By adjusting the value of a1/a2 within the above range it is beneficial to improve the cycle performance and storage performance of the electrochemical device at the same time, and maintain a high specific capacity of the positive electrode, thereby improving the overall performance of the electrochemical device.
  • the mass percentage of Al in the first region is 0.01% to 0.5%.
  • the mass percentage of Al in the first region may be 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, or any range therebetween.
  • the positive electrode active material is selected from lithium manganese oxide (LMO) including Al element.
  • the molar ratio a1 of Al/Mn in the first region is 1% to 30%, preferably 5% to 30%, and/or the molar ratio a2 of Al/Mn in the second region is 0.05% to 5%.
  • the molar ratio a1 of Al/Mn in the first region may be 1%, 5%, 10%, 15%, 20%, 25%, 30%, or any range therebetween.
  • the molar ratio a2 of Al/Mn in the second region may be 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, or any range therebetween.
  • the molar ratio a1 of Al/Mn in the first region is too small (for example, less than 1%), not only the manganese dissolution phenomenon of the positive electrode cannot be improved to improve the cycle performance and storage performance of the electrochemical device, but the introduction of Al will to a certain extent reduce the specific capacity of the positive electrode.
  • the molar ratio a1 of Al/Mn in the first region is too large (for example greater than 30%), the total Al content in the positive electrode active material will increase, which will reduce the specific capacity of the positive electrode.
  • the molar ratio a2 of Al/Mn in the second region is too small (eg, less than 0.05%) or too large (eg, greater than 0.5%), it is not conducive to improving the cycle performance and storage performance of the electrochemical device.
  • the molar ratio a1 of Al/Mn in the first region and/or the molar ratio a2 of Al/Mn in the second region are within the scope of the application, it is beneficial to improve the cycle performance and storage performance of the electrochemical device at the same time, and The positive electrode maintains a high specific capacity, thereby improving the overall performance of the electrochemical device.
  • the positive electrode active material satisfies at least one of the conditions (a) to (c): (a) the molar ratio of Al/Mn in the positive electrode active material is 0.1% to 10%, preferably 2 % to 10%; (b) Mn elements include Mn 3+ and Mn 4+ , the ratio of the molar ratio of Mn 3+ /Mn 4+ in the first region to the molar ratio of Mn 3+ /Mn 4+ in the second region e is 0.8 to 0.95; (c) the positive electrode active material also includes Li, the molar ratio of Li/Mn in the first region is b1, and the molar ratio of Li/Mn in the second region is b2, satisfying 1 ⁇ b1/b2 ⁇ 2 , preferably 1.1 ⁇ b1/b2 ⁇ 2.
  • the molar ratio of Al/Mn in the positive electrode active material can be 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or for any range in between.
  • the value of e can be 0.8, 0.83, 0.85, 0.87, 0.9, 0.92, 0.95 or any range therebetween.
  • the value of b1/b2 may be 1, 1.1, 1.2, 1.4, 1.6, 1.8, 2 or any range therebetween.
  • the molar ratio of Al/Mn in the positive electrode active material is too small (for example, less than 0.1%), the manganese dissolution phenomenon of the positive electrode is not significantly improved, and thus the cycle performance and storage performance of the electrochemical device are not significantly improved.
  • the molar ratio of Al/Mn in the positive electrode active material is too large (for example greater than 10%), the specific capacity of the positive electrode will decrease.
  • the mass percentage of Al is 0.005% to 0.1%.
  • the mass percentage of Al in the positive electrode active material may be 0.005%, 0.01%, 0.02%, 0.05%, 0.08%, 0.1%, or any range therebetween.
  • the mass percentage of Mn is 1.0% to 1.2%.
  • the ratio e of the molar ratio of Mn 3+ /Mn 4+ in the first area to the molar ratio of Mn 3+ /Mn 4+ in the second area is within the scope of the application, which is conducive to improving the manganese stripping phenomenon, thereby improving the electrochemistry The cycle performance and storage performance of the device.
  • the present application has no special restrictions on the molar ratio of Mn 3+ /Mn 4+ in the first area and the molar ratio of Mn 3+ /Mn 4+ in the second area, as long as the range of e is satisfied, for example, in the first area
  • the molar ratio of Mn 3+ /Mn 4+ is 15% to 55%
  • the molar ratio of Mn 3+ /Mn 4+ in the second region is 30% to 70%.
  • the ratio b1/b2 of the molar ratio b1 of Li/Mn in the first region to the molar ratio b2 of Li/Mn in the second region is within the above range, so that the molar ratio b1 of Li/Mn in the first region is larger than that in the second region
  • the molar ratio b2 of Li/Mn is beneficial to improve the cycle performance of the electrochemical device and maintain a high specific capacity of the positive electrode.
  • the Li/Mn molar ratio b1 in the first region is 58% to 98%
  • the Li/Mn molar ratio b2 in the second region is 55% to 60%.
  • the molar ratio b1 of Li/Mn in the first region can be 58%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, or any range therebetween
  • the molar ratio b2 of Li/Mn in the second region can be 55%, 55.5%, 56%, 56.5%, 57%, 57.5%, 58%, 58.5%, 59%, 59.5%, 60% or between any range.
  • the positive electrode active material also includes M1 elements, and the M1 elements include at least one of Ni, Co, Nb, Mo, V, W, Zr, Mg, Ti, La, Y or B elements,
  • the positive electrode active material satisfies at least one of the following conditions (d) to (e): (d) the molar ratio of M1/Mn is 0.1% to 5%; (e) the molar ratio of Al/M1 is 1 to 10.
  • the molar ratio of M1/Mn can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any range therebetween.
  • the molar ratio of Al/M1 can be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10 or any range therebetween.
  • the positive electrode active material includes M1 element, and the molar ratio of M1/Mn and/or the molar ratio of Al/M1 is within the above range, which is beneficial to improve the storage performance of the electrochemical device and maintain a high specific capacity of the positive electrode.
  • the positive electrode active material further includes an M2 element, the M2 element includes F and/or S, and the mass percentage of the M2 element is 0.1% to 2% based on the mass of the positive electrode active material.
  • the mass percentage content of the M2 element can be 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, or any range therebetween.
  • the mass percentage of the M2 element When the mass percentage of the M2 element is too low (for example, less than 0.1%), the improvement of the performance of the electrochemical device is not obvious. As the mass percentage of the M2 element increases, it is beneficial to improve the specific capacity of the positive electrode. However, when the mass percentage of the M2 element is too high (for example higher than 2%), the cycle performance of the electrochemical device will be deteriorated. By adjusting the mass percentage content of the M2 element within the above range, it is beneficial to improve the cycle performance of the electrochemical device and maintain a high specific capacity of the positive electrode.
  • the M2 element includes F element, the molar ratio of F/Mn in the first region is d1, and the molar ratio of F/Mn in the second region is d2, satisfying 3 ⁇ d1/d2 ⁇ 50, Preferably, 3 ⁇ d1/d2 ⁇ 25.
  • the value of d1/d2 may be 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 or any range therebetween.
  • M2 element into the positive electrode active material can improve the cycle performance of the electrochemical device, but excessive M2 element will affect the specific capacity of the positive electrode.
  • the molar ratio d1 of F/Mn in the first region is greater than the molar ratio d2 of F/Mn in the second region, that is, the F element is enriched near the positive electrode.
  • the area on the surface of the active material can improve the cycle performance of the electrochemical device while maintaining a high specific capacity of the positive electrode.
  • the present application has no special restrictions on the molar ratio d1 of F/Mn in the first region and the molar ratio d2 of F/Mn in the second region, as long as the range of d1/d2 is satisfied, for example, the ratio of F/Mn in the first region
  • the molar ratio d1 is 1% to 2.5%
  • the F/Mn molar ratio d2 in the second region is 0.05% to 0.5%.
  • the positive electrode active material also includes Nb element, the molar ratio of Nb/Mn in the first region is c1, and the molar ratio of Nb/Mn in the second region is c2, satisfying 3 ⁇ c1/c2 ⁇ 50.
  • the value of c1/c2 may be 3, 10, 15, 20, 25, 30, 35, 40, 45 or any range therebetween.
  • Nb element into the positive electrode active material and the value of c1/c2 within the above range is beneficial to improve the cycle performance of the electrochemical device.
  • the present application has no special restrictions on the molar ratio c1 of Nb/Mn in the first region and the molar ratio c2 of Nb/Mn in the second region, as long as the range of c1/c2 is satisfied, for example, Nb/Mn in the first region
  • the molar ratio c1 of the second region is 1% to 5%
  • the molar ratio c2 of Nb/Mn in the second region is 0.1% to 0.8%.
  • the Dv99 of the positive electrode active material is 15 ⁇ m to 50 ⁇ m, preferably 25 ⁇ m to 35 ⁇ m, and the particle size of the positive electrode active material satisfies at least one of the conditions (i) to (ii): (i) 5 ⁇ m ⁇ Dv90 ⁇ 30 ⁇ m, 5 ⁇ m ⁇ Dv99-Dv90 ⁇ 21 ⁇ m, preferably 8 ⁇ m ⁇ Dv99-Dv90 ⁇ 12 ⁇ m; (ii) 2 ⁇ m ⁇ Dv10 ⁇ 10 ⁇ m, 1 ⁇ (Dv99-Dv10)/Dv50 ⁇ 4, preferably 4 ⁇ m ⁇ Dv10 ⁇ 7 ⁇ m, 2 ⁇ (Dv99-Dv10)/Dv50 ⁇ 3.
  • the Dv99 of the positive electrode active material may be 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 35 ⁇ m, 40 ⁇ m, 45 ⁇ m, 50 ⁇ m or any range therebetween.
  • the Dv90 of the positive electrode active material can be 5 ⁇ m, 8 ⁇ m, 10 ⁇ m, 13 ⁇ m, 15 ⁇ m, 18 ⁇ m, 20 ⁇ m, 23 ⁇ m, 25 ⁇ m, 28 ⁇ m, 30 ⁇ m or any range therebetween, and the value of Dv99-Dv90 can be 5 ⁇ m, 8 ⁇ m, 10 ⁇ m, 12 ⁇ m, 15 ⁇ m, 18 ⁇ m, 20 ⁇ m, 21 ⁇ m or any range therebetween.
  • the Dv10 of the positive electrode active material can be 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 10 ⁇ m or any range therebetween, and the value of (Dv99-Dv10)/Dv50 can be 1, 1.5, 2, 2.5, 3, 3.5, 4 or any range in between.
  • the preparation method of the positive electrode active material may include but not limited to the following steps: mixing the raw materials at T1 temperature for the first calcination, the calcination time is t1, to obtain the intermediate product; then adding the intermediate raw material and the intermediate product to mix, at T2 The second calcination is carried out at the temperature, and the calcination time is t2 to obtain the positive electrode active material.
  • the present application has no special restrictions on the temperature T1 and calcination time t1 of the first calcination, and the temperature T2 and calcination time t2 of the second calcination, as long as the purpose of the application can be achieved, for example, T1 is 800°C to 900°C , t1 is 35h to 45h, T2 is 450°C to 600°C, t2 is 5h to 15h.
  • the present application has no special restrictions on the above-mentioned raw materials and intermediate raw materials, as long as the purpose of the present application can be achieved.
  • the raw materials and intermediate raw materials can each independently include but not limited to MnO 2 , Li 2 CO 3 or Al 2 O 3 at least one.
  • the calcination temperature and calcination time usually affect the distribution of elements in the positive electrode active material in the positive electrode active material particles. For example, the reduction of the calcination temperature and/or the shortening of the calcination time will cause the elements to be distributed in the area close to the surface of the positive electrode active material particles, such as , the first area of the present application; increasing the calcination temperature and/or prolonging the calcination time will cause the elements to be distributed in the area away from the surface of the positive electrode active material particles, for example, the second area of the present application.
  • the method of introducing element M1 into the positive electrode active material there is no particular limitation on the method of introducing element M1 into the positive electrode active material, as long as the purpose of this application can be achieved, for example, adding a compound containing M1 during the preparation of the positive electrode active material.
  • This application has no special restrictions on the compound containing M1, as long as the purpose of this application can be achieved, for example, it may include but not limited to MgO, nickel acetate, TiO 2 , ZrO 2 , Nb 2 O 5 , MoO 3 , V 2 O 5. At least one of WO 3 or Y 2 O 3 .
  • the method of introducing element M2 into the positive electrode active material there is no particular limitation on the method of introducing element M2 into the positive electrode active material, as long as the purpose of this application can be achieved, for example, adding a compound containing M2 during the preparation of the positive electrode active material.
  • the present application has no special limitation on the compound containing M2, as long as the purpose of the present application can be achieved, for example, it may include but not limited to at least one of MnS or LiF.
  • the second aspect of the application provides an electrochemical device, including a positive electrode, a negative electrode and an electrolyte
  • the positive electrode includes the positive electrode active material in any embodiment of the application
  • the positive electrode includes a positive electrode material layer and a positive electrode current collector
  • the positive electrode material layer includes the first A positive electrode material layer and a second positive electrode material layer
  • the first positive electrode material layer is located between the second positive electrode material layer and the positive electrode current collector
  • the content of the Mn element in the first positive electrode material layer is greater than the content of the Mn element in the second positive electrode material layer .
  • the content of Mn element in the first positive electrode material layer is greater than the content of Mn element in the second positive electrode material layer, which is beneficial to reduce the dissolution of manganese in the positive electrode, thereby improving the cycle performance and storage performance of the electrochemical device.
  • the electrolyte satisfies at least one of the conditions (iii) to (v): (iii) the electrolyte includes a chain carbonate, and the mass of the chain carbonate is 100% The content is 20% to 60%, chain carbonates include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethylene propyl carbonate (EPC) or at least one of ethyl methyl carbonate (EMC); (iv) the electrolyte includes benzene-containing compounds, and the mass percentage of benzene-containing compounds is 0.01% to 5%, preferably 0.01% to 3%, Further preferably 1% to 3%, the benzene-containing compound includes at least one of biphenyl (BP), fluorobenzene (FP) or cyclohexylbenzene (CHB); (v
  • the mass percentage of chain carbonate can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, or any range therebetween.
  • the mass percentage of the benzene-containing compound may be 0.01%, 0.05%, 0.1%, 1%, 2%, 3%, 4%, 5% or any range therebetween.
  • the mass percentage of polystyrene can be 0.01%, 0.05%, 0.1%, 1%, 2%, 3%, 4%, 5% or any range therebetween.
  • At least one of chain carbonate, benzene-containing compound or polystyrene in the electrolyte, and its mass percentage is within the above range, which is conducive to the formation of a synergistic effect between the positive electrode active material and the electrolyte , thereby improving the cycle performance and storage performance of electrochemical devices.
  • the negative electrode includes a negative electrode material layer, the negative electrode material layer includes a negative electrode active material, the negative electrode active material includes at least one of natural graphite, artificial graphite or hard carbon, and the electrochemical device satisfies the conditions (vi) to At least one of (ix): (vi) 2 ⁇ m ⁇ Dv10 ⁇ 10 ⁇ m of the negative electrode active material, preferably 3 ⁇ m ⁇ Dv10 ⁇ 8 ⁇ m; (vii) 5 ⁇ m ⁇ Dv90 ⁇ 20 ⁇ m of the negative electrode active material, 5 ⁇ m ⁇ Dv99-Dv90 ⁇ 25 ⁇ m , preferably 5 ⁇ m ⁇ Dv90 ⁇ 15 ⁇ m, 5 ⁇ m ⁇ Dv99-Dv90 ⁇ 10 ⁇ m; (viii) the value of the orientation index (OI) of the negative electrode active material is 5 to 30, preferably 8 to 20; (ix) the value of the negative electrode active material The degree of graphitization is 92% to 96%, preferably 93% to 9
  • the Dv10 of the negative electrode active material may be 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 10 ⁇ m or any range therebetween.
  • the Dv90 of the negative electrode active material can be 5 ⁇ m, 8 ⁇ m, 10 ⁇ m, 13 ⁇ m, 15 ⁇ m, 18 ⁇ m, 20 ⁇ m or any range therebetween, and the value of Dv99-Dv90 can be 5 ⁇ m, 8 ⁇ m, 10 ⁇ m, 13 ⁇ m, 15 ⁇ m, 18 ⁇ m, 20 ⁇ m, 23 ⁇ m, 25 ⁇ m or any range in between.
  • the value of OI of the negative electrode active material may be 5, 8, 10, 13, 15, 18, 20, 23, 25, 28, 30 or any range therebetween.
  • the degree of graphitization of the negative electrode active material may be 92%, 93%, 94%, 95%, 96%, or any range therebetween.
  • the negative electrode active material By adjusting at least one of the Dv10 of the negative electrode active material, the Dv10, Dv90 and Dv99-Dv90 value of the negative electrode active material, the OI value of the negative electrode active material or the degree of graphitization of the negative electrode active material within the scope of the present application, it is beneficial to the negative electrode A synergistic effect is formed among the active material, positive electrode active material, and electrolyte, which is beneficial to improve the cycle performance and storage performance of the electrochemical device.
  • the electrochemical device includes a separator, and the onset exothermic temperature of the separator tested by differential scanning calorimetry (DSC) is 138°C to 145°C, preferably 141°C to 143°C, More preferably, it is 141°C to 142°C.
  • the onset exothermic temperature of the isolation film tested by differential scanning calorimetry is 138°C, 139°C, 140°C, 141°C, 142°C, 143°C, 144°C, 145°C or any range therebetween.
  • the molar ratio of different elements in the positive electrode active material is calculated by disassembling the electrochemical device containing the positive electrode active material at 0% state of charge to obtain the positive electrode, and then testing to obtain the contents of different elements.
  • the positive electrode current collector is not particularly limited, as long as the purpose of the present application can be achieved, for example, it may include but not limited to aluminum foil, aluminum alloy foil, or a composite current collector.
  • the thickness of the positive electrode collector there is no particular limitation on the thickness of the positive electrode collector, as long as the purpose of the present application can be achieved, for example, the thickness is 8 ⁇ m to 12 ⁇ m.
  • the positive electrode material layer includes the positive electrode active material in any of the foregoing embodiments of the present application, and the positive electrode material layer may also include a binder.
  • This application has no special restrictions on the binder, as long as the purpose of the application can be achieved
  • a conductive agent can also be used in the positive electrode material layer.
  • the present application has no special restrictions on the conductive agent, as long as the purpose of the application can be realized, for example, it can include but not limited to conductive carbon black (Super P), carbon nanotubes ( At least one of CNTs), carbon fiber, flake graphite, Ketjen black, graphene, metal material or conductive polymer.
  • the aforementioned carbon nanotubes may include, but are not limited to, single-walled carbon nanotubes and/or multi-walled carbon nanotubes.
  • the aforementioned carbon fibers may include, but are not limited to, vapor grown carbon fibers (VGCF) and/or carbon nanofibers.
  • the above metal material may include but not limited to metal powder and/or metal fiber, specifically, the metal may include but not limited to at least one of copper, nickel, aluminum or silver.
  • the aforementioned conductive polymer may include but not limited to at least one of polyphenylene derivatives, polyaniline, polythiophene, polyacetylene or polypyrrole.
  • the positive electrode may further include a conductive layer located between the positive electrode current collector and the positive electrode material layer.
  • the present application has no particular limitation on the composition of the conductive layer, which may be a commonly used conductive layer in the field, for example, may include but not limited to the above-mentioned conductive agent and the above-mentioned binder.
  • the negative electrode may include a negative electrode current collector.
  • the negative electrode current collector of this application is not particularly limited, as long as the purpose of this application can be achieved, it may include but not limited to copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil , nickel foam, copper foam or composite current collectors, etc.
  • the thickness of the current collector of the negative electrode there is no particular limitation on the thickness of the current collector of the negative electrode, as long as the purpose of the present application can be achieved, for example, the thickness is 4 ⁇ m to 12 ⁇ m.
  • the negative electrode material layer may be provided on one surface in the thickness direction of the negative electrode current collector, or on two surfaces in the thickness direction of the negative electrode current collector. It should be noted that the "surface” here may be the entire area of the negative electrode collector, or a partial area of the negative electrode collector. This application is not particularly limited, as long as the purpose of this application can be achieved.
  • the negative electrode material layer may also include a conductive agent.
  • the present application has no special limitation on the conductive agent, as long as the purpose of the present application can be achieved, for example, it may include but not limited to at least one of the above-mentioned conductive agents.
  • the negative electrode material layer may also include a binder, and the present application has no special restrictions on the binder, as long as the purpose of the application can be achieved, for example, it may include but not limited to at least one of the above-mentioned binders .
  • the negative electrode may further include a conductive layer located between the negative electrode current collector and the negative electrode material layer.
  • the present application has no particular limitation on the composition of the conductive layer, which may be a commonly used conductive layer in the field, and the conductive layer may include but not limited to the above-mentioned conductive agent and the above-mentioned binder.
  • This application has no special restrictions on the separator, as long as the purpose of this application can be achieved, for example, it can include but not limited to polyethylene (PE), polypropylene (PP), polytetrafluoroethylene-based polyolefin (PO) separators , polyester film (such as polyethylene terephthalate (PET) film), cellulose film, polyimide film (PI), polyamide film (PA), spandex, aramid film, woven film, non At least one of woven film (non-woven fabric), microporous film, composite film, separator paper, laminated film or spun film, preferably PP.
  • PET polyethylene terephthalate
  • PI polyimide film
  • PA polyamide film
  • aramid film woven film
  • woven film non At least one of woven film (non-woven fabric), microporous film, composite film, separator paper, laminated film or spun film, preferably PP.
  • the separator of the present application may have a porous structure, and the pore size is not particularly limited as long as the purpose of the present application can be achieved, for example, the pore size may be 0.01 ⁇ m to 1 ⁇ m.
  • the thickness of the isolation film is not particularly limited, as long as the purpose of the present application can be achieved, for example, the thickness may be 5 ⁇ m to 500 ⁇ m, preferably 25 ⁇ m.
  • a separator may include a substrate layer and a surface treatment layer.
  • the substrate layer can be a non-woven fabric, film or composite film with a porous structure, and the material of the substrate layer can include but not limited to polyethylene, polypropylene, polyethylene terephthalate or polyimide, etc. at least one of .
  • a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric, or a polypropylene-polyethylene-polypropylene porous composite film may be used.
  • at least one surface of the substrate layer is provided with a surface treatment layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic material.
  • the inorganic material layer may include but not limited to inorganic particles and binders, and the present application has no particular limitation on inorganic particles, for example, may include but not limited to aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium oxide, tin oxide, At least one of ceria, nickel oxide, zinc oxide, calcium oxide, zirconia, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate.
  • the present application has no special limitation on the binder, for example, it may include but not limited to polyvinylidene fluoride, copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate , polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene or polyhexafluoropropylene.
  • the polymer layer contains a polymer, and the polymer material may include but not limited to polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinyl pyrrolidone, polyvinyl ether, polyvinylidene fluoride At least one of ethylene, poly(vinylidene fluoride-hexafluoropropylene), and the like.
  • lithium salts may also be included in the electrolyte.
  • This application has no particular limitation on lithium salts, as long as the purpose of this application can be achieved, for example, it may include but not limited to 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 or lithium difluoroborate A sort of.
  • the lithium salt comprises LiPF 6 .
  • non-aqueous solvents may also be included in the electrolytic solution.
  • the present application has no special limitation on non-aqueous solvents, as long as the purpose of the application can be achieved, for example, it may include but not limited to carbonate compounds, carboxylate compounds, At least one of ether compounds or other organic solvents.
  • the aforementioned carbonate compounds may include, but are not limited to, at least one of cyclic carbonate compounds and/or fluorocarbonate compounds.
  • the above-mentioned cyclic carbonate may include but not limited to ethylene carbonate (also known as ethylene carbonate, referred to as EC), propylene carbonate (PC), butylene carbonate (BC) or vinyl ethylene carbonate (VEC) at least one of the Fluorocarbonate compounds may include but are not limited to fluoroethylene carbonate (also known as fluoroethylene carbonate, referred to as FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate ester, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1- Methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate or trifluoromethylethylene carbonate at least one.
  • fluoroethylene carbonate also known as fluoroethylene carbonate, referred to as FEC
  • FEC fluoroethylene carbon
  • carboxylate compounds may include but are not limited to methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyl At least one of lactone, decanolactone, valerolactone, mevalonolactone or caprolactone.
  • the aforementioned ether compounds may include, but are not limited to, dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxy At least one of methoxyethane, 2-methyltetrahydrofuran or tetrahydrofuran.
  • the above-mentioned other organic solvents may include but not limited to dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2- At least one of pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate or phosphoric acid ester. Based on the quality of the electrolyte, the mass percentage of the above-mentioned non-aqueous solvent is 15% to 80%, such as 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or between any range of .
  • the electrochemical device of the present application is not particularly limited, and it may include any device that undergoes an electrochemical reaction.
  • the electrochemical device may include, but is not limited to, a lithium metal secondary battery, a lithium ion secondary battery (lithium ion battery), a lithium polymer secondary battery, or a lithium ion polymer secondary battery, among others.
  • the preparation process of electrochemical devices is well known to those skilled in the art, and the present application is not particularly limited.
  • it may include but not limited to the following steps: stack the positive electrode, separator and negative electrode in sequence, and wind it as needed , folding and other operations to obtain the electrode assembly with a winding structure, put the electrode assembly into the packaging bag, inject the electrolyte into the packaging bag and seal it, and obtain an electrochemical device; or stack the positive electrode, separator and negative electrode in order, and then use Tape is used to fix the four corners of the entire laminated structure to obtain the electrode assembly of the laminated structure, the electrode assembly is placed in a packaging bag, the electrolyte is injected into the packaging bag and sealed to obtain an electrochemical device.
  • overcurrent prevention elements, guide plates, etc. can also be placed in the packaging bag as needed, so as to prevent pressure rise and overcharge and discharge inside the electrochemical device.
  • the third aspect of the present application provides an electronic device, comprising the electrochemical device in any one of the foregoing embodiments of the present application.
  • the electrochemical device provided by the application has good cycle performance and storage performance, and the positive electrode has a high specific capacity, so the electronic device provided by the application has a long service life and good performance.
  • 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, video recorders , 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.
  • the application provides a positive electrode active material, including Mn element and Al element, the positive electrode active material particle includes a first region near the surface of the positive electrode active material particle and a second region away from the surface of the positive electrode active material particle, in the first region Al/
  • the molar ratio of Mn is a1
  • the molar ratio of Al/Mn in the second region is a2, satisfying 1.1 ⁇ a1/a2 ⁇ 100.
  • the positive electrode Al in the active material is enriched in the area close to the surface of the positive electrode active material, which can not only effectively improve the manganese dissolution phenomenon of the positive electrode to improve the cycle performance and storage performance of the electrochemical device, but also reduce the total content of Al in the positive electrode active material to The positive electrode maintains a high specific capacity, thereby improving the overall performance of the electrochemical device.
  • Figure 1 is a schematic cross-sectional view of positive electrode active material particles in some embodiments of the present application.
  • Reference numerals 10, positive electrode active material, 11, first area, 12, second area.
  • Fig. 1 shows the schematic cross-sectional view of the positive electrode active material particle in some embodiments of the present application, as can be seen, the first region 11 is the region near the surface of the particle of the positive electrode active material 10, and the second region 12 is away from the positive electrode active material 10 area of the particle's surface.
  • a lithium-ion battery is used as an example of an electrochemical device to explain the present application, but the electrochemical device of the present application is not limited to the lithium-ion battery.
  • the dried sample is tested using an inductively coupled plasma emission spectrometer (model Thermo ICAP6300), and the molar ratio between different elements in the second region can be calculated, such as the molar ratio of Al/Mn and the molar ratio of Li/Mn Ratio, molar ratio of Nb/Mn and molar ratio of F/Mn, etc.
  • the molar ratio of Mn 3+ /Mn 4+ in the first region and the second region of the cathode active material was analyzed by X-ray photoelectron spectroscopy (XPS).
  • the lithium-ion battery Under the condition of 25°C, charge the lithium-ion battery with a constant current of 0.5C to 4.2V, then charge it with a constant voltage of 4.2V to 0.05C, and then discharge it with a constant current of 1C to 2.8V, and record the discharge capacity as D 01 ;
  • the lithium-ion battery is subjected to a cycle of "0.5C charge-1C discharge" for several times, and the cycle is 500 cycles, and the discharge capacity after the 500th cycle is tested to be D 1 .
  • Capacity retention (%) after 500 cycles at 25°C D 1 /D 01 ⁇ 100%.
  • the specific test procedure is as follows: put the lithium-ion battery at 25°C for 30 minutes, then charge it to 4.2V at a rate of 0.2C, charge it at a constant voltage of 4.2V to 0.05C, let it stand for 30 minutes, and then charge it at a rate of 0.5C. Discharge to 2.8V, and record the discharge capacity at this time as the stored capacity of the lithium-ion battery.
  • 60°C high temperature storage capacity retention rate capacity after storage / capacity before storage ⁇ 100%.
  • Each embodiment or comparative example tests 4 lithium-ion batteries, and taking the average value is the final result.
  • the positive electrode and lithium metal in the examples or comparative examples to make a button battery, and charge the button battery at a charging current of 0.5C (that is, the current value that completely discharges the theoretical capacity within 2h) in an environment of 25°C.
  • a charging current of 0.5C that is, the current value that completely discharges the theoretical capacity within 2h
  • the ratio of the initial discharge capacity to the mass of the positive electrode is recorded as the specific capacity of the positive electrode.
  • 4 positive poles were tested, and the average value was taken as the final result.
  • the mass of the positive electrode is the mass after subtracting the positive electrode current collector.
  • the preparation method of the button battery is prepared by a preparation method known in the art, and the electrolyte in the button battery is the electrolyte used in each embodiment or comparative example.
  • DSC is used for testing, and the DSC curve of the isolation film is obtained at a heating rate of 10°C/min, and the initial exothermic temperature of the isolation film can be obtained from the DSC curve.
  • Dv10, Dv50, Dv90, and Dv99 are respectively the cumulative diameters of 10%, 50%, 90%, and 99% of the particle volume benchmark distribution obtained by using a laser scattering particle size analyzer.
  • Li 2 CO 3 and intermediate products are mixed, and calcined at temperature T2 for calcination time t2 to obtain lithium manganate (LMO) containing Al element as the positive electrode active material.
  • LMO lithium manganate
  • the Al/Mn molar ratio of Al in Al2O3 added during secondary calcination and Mn in the intermediate product is x2, and the ratio of Li in Li2CO3 added during secondary calcination to Mn in the intermediate product
  • the Li/Mn molar ratio is y2; the raw material MnO 2 contains Al and the Al/Mn molar ratio is x0.
  • the Dv99 of the positive electrode active material is 45 ⁇ m, the Dv90 is 26 ⁇ m, the Dv50 is 11.2 ⁇ m, and the Dv10 is 6 ⁇ m.
  • NMP N-methylpyrrolidone
  • the positive electrode slurry was uniformly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 12 ⁇ m, and the aluminum foil was dried at 120° C. for 1 hour to obtain a positive electrode coated with a positive electrode material layer on one side.
  • Negative electrode active material artificial graphite, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), thickener sodium carboxymethylcellulose (CMC) are mixed according to the mass ratio of 95:2:2:1, add to Ionized water was stirred evenly under the action of a vacuum mixer to obtain negative electrode slurry, wherein the solid content of the negative electrode slurry was 75 wt%.
  • the negative electrode slurry was uniformly coated on one surface of the negative electrode current collector copper foil with a thickness of 12 ⁇ m, and the copper foil was dried at 120° C. to obtain a negative electrode with a coating thickness of 130 ⁇ m coated with a negative electrode material layer on one side.
  • the Dv99 of the negative electrode active material is 30 ⁇ m
  • the Dv90 is 18 ⁇ m
  • the Dv10 is 5 ⁇ m
  • the OI value is 18, and the graphitization degree is 96%.
  • EC, PC, DEC, and EMC are mixed according to a mass ratio of 5:1:4:7 to obtain an organic solvent, and then lithium salt LiPF is added to the organic solvent to dissolve and mix evenly to obtain electrolyte.
  • the mass percent content of LiPF 6 in the electrolyte is 12.5%, and the rest is organic solvent.
  • a porous polyethylene film (provided by Celgard) with a thickness of 7 ⁇ m was used, and the onset exothermic temperature of the separator was 141° C.
  • the positive electrode, separator, and negative electrode prepared above are stacked in order, so that the separator is placed between the positive electrode and the negative electrode to play the role of isolation, and the electrode assembly is obtained by winding.
  • Put the electrode assembly in an aluminum-plastic film packaging bag inject electrolyte after drying, and obtain a lithium-ion battery through processes such as vacuum packaging, standing, chemical formation, degassing, and edge trimming.
  • the compound corresponding to the M1 element is added during the primary calcination so that the M1/Mn molar ratio is 1.0%; the compound corresponding to the M1 element is added during the second calcination so that M1 is mixed with the intermediate product
  • the molar ratio of Mn was 2.6%, and the molar ratio of each element was prepared as the positive electrode active material shown in Table 3, and the others were the same as in Examples 1-4.
  • the compound corresponding to the M1 element and its content are adjusted and added during the primary calcination so that the M1/Mn molar ratio is 1.0%; the compound corresponding to the M1 element is added during the second calcination so that M1
  • the molar ratio of Mn in the intermediate product was 1.0%, and the positive electrode active material was obtained except that the molar ratio of each element was shown in Table 3, and the rest were the same as in Examples 1-4.
  • Example 1-4 Except for adjusting relevant preparation parameters according to Table 4, the others are the same as in Example 1-4.
  • Comparative Example 1-1 to Comparative Example 1-2 From Example 1-1 to Example 1-8, Comparative Example 1-1 to Comparative Example 1-2, it can be seen that when the molar ratio a1 of Al/Mn in the first region of the positive electrode active material is the same as that of Al in the second region
  • the ratio a1/a2 of the molar ratio a2 of Mn within the scope of the present application can simultaneously improve the specific capacity of the positive electrode in the electrochemical device, the cycle performance and the storage performance of the electrochemical device.
  • the value of e is within the range of the present application, the obtained electrochemical device has good cycle performance and storage performance, and the positive electrode in the electrochemical device also has a higher specific capacity.
  • Example 1-1 to Example 1-8, and Comparative Example 1-1 it can be seen that when the molar ratio a1 of Al/Mn in the first region is within the scope of the present application, the obtained electrochemical device has good properties at the same time. Cycling performance and storage performance, the positive electrode in the electrochemical device also has a high specific capacity. From Example 1-1 to Example 1-8, it can be seen that when the molar ratio a2 of Al/Mn in the second region and the Al/Mn molar ratio of the positive electrode active material are within the scope of the present application, the obtained electrochemical device At the same time, it has good cycle performance and storage performance, and the positive electrode in the electrochemical device also has a high specific capacity.
  • Example 2-1 to Example 2-4 it can be seen that when the molar ratio b1 of Li/Mn in the first region of the positive electrode active material and the molar ratio b2 of Li/Mn in the second region If the ratio b1/b2 is within the scope of the present application, the obtained electrochemical device has good cycle performance and storage performance, and the positive electrode in the electrochemical device also has a high specific capacity. As the value of b1/b2 increases, the cycle performance and storage performance of the electrochemical device show a gradual upward trend.
  • the compound corresponding to Mg is MgO
  • the compound corresponding to Ni is nickel acetate
  • the compound corresponding to Ti is TiO 2
  • the compound corresponding to Zr is ZrO 2
  • the compound corresponding to Nb is The compound is Nb 2 O 5
  • the compound corresponding to S is MnS
  • the compound corresponding to F is LiF; "/" in Table 3 indicates that there is no corresponding preparation parameter or substance.
  • Example 3-1 to Example 3-14 it can be seen that the addition of M1 element and/or M2 element can further improve the cycle performance and storage performance of the electrochemical device, and the positive electrode in the electrochemical device specific capacity.
  • Example 3-1 to Example 3-9 it can be seen that when the M1 element within the scope of the application is introduced into the positive electrode active material, and the values of M1/Mn molar ratio, Al/M1 molar ratio, and c1/c2 are within the scope of the present application, the obtained electrochemical device has good cycle performance and storage performance, and the positive electrode in the electrochemical device also has a high specific capacity.
  • Example 3-10 to Example 3-13 it can be seen that when the M2 element within the scope of the application is introduced in the positive electrode active material, and the mass percentage of the M2 element, the value of d1/d2 is within the scope of the application Inside, the obtained electrochemical device has good cycle performance and storage performance at the same time, and the positive electrode in the electrochemical device also has a high specific capacity. It can be seen from Examples 1-4 and Examples 3-14 that the simultaneous introduction of the M1 element and the M2 element can further improve the cycle performance and storage performance of the electrochemical device, as well as the specific capacity of the positive electrode in the electrochemical device.
  • the particle size of cathode active materials generally affects the performance of electrochemical devices, for example, cycle performance and storage performance.
  • Example 4-1 to Example 4-3 it can be seen from Examples 1-4, Example 4-1 to Example 4-3 that when the value of Dv90, Dv10, Dv99-Dv90, (Dv99-Dv10)/Dv50 of the positive electrode active material is within the scope of the present application Inside, the obtained electrochemical device has good cycle performance and storage performance at the same time, and the positive electrode in the electrochemical device also has a high specific capacity.
  • the types and contents of components in the electrolyte of electrochemical devices usually affect the performance of electrochemical devices, such as cycle performance and storage performance.
  • Example 1-4, Example 5-1 to Example 5-3 it can be seen that when the electrolyte includes a benzene compound and its type and mass percentage are within the scope of the application, the electrochemical device obtained At the same time, it has better cycle performance and storage performance.
  • Examples 1-4, Examples 5-4 and Examples 5-5 when PS is included in the electrolyte and its mass percentage is within the scope of the present application, the obtained electrochemical device has better properties at the same time. Cycle performance and storage performance. It can be seen from Examples 1-4 and Examples 5-6 that the benzene-containing compound and PS have good additive properties, which can further improve the cycle performance and storage performance of the electrochemical device.

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Abstract

提供一种正极活性材料（10），包含该正极活性材料（10）的电化学装置和电子装置，正极活性材料（10）包括Mn元素和Al元素，正极活性材料（10）颗粒包括靠近正极活性材料（10）颗粒表面的第一区域（11）和远离正极活性材料（10）颗粒表面的第二区域（12），第一区域（11）中Al/Mn的摩尔比为a1，第二区域（12）中Al/Mn的摩尔比为a2，满足1.1≤a1/a2≤100。使Al富集在靠近正极活性材料（10）表面的区域，不仅能够有效改善正极的锰溶出现象来提高电化学装置的循环性能和存储性能，同时可以减少Al在正极活性材料中的总含量以保持正极极片的比容量，从而提高电化学装置的综合性能。

Description

一种正极活性材料、包含该正极活性材料的电化学装置和电子装置 技术领域
本申请涉及电化学领域，特别是涉及一种正极活性材料、包含该正极活性材料的电化学装置和电子装置。
背景技术
锂离子电池由于具有高能量密度、长循环寿命及无记忆效应等优点而被广泛应用于穿戴设备、智能手机、无人机、电动汽车及大型储能等设备等领域，已成为当今世界最具发展潜力的新型绿色化学电源，但也对锂离子电池的综合性能提出更高的要求。
锂离子电池中的正极活性材料是影响锂离子电池性能的重要参数，其中，正极活性材料锰酸锂被广泛应用于锂离子电池中，但是锰酸锂中存在的Mn 3+易发生歧化反应，导致Mn 2+溶出，然后通过电解液迁移至负极，破坏固体电解质界面(SEI)，造成活性锂损失，从而恶化锂离子电池的循环性能。在相关技术中，在改善Mn 2+溶出的同时往往伴随着正极比容量的衰减、电化学装置循环性能或存储性能恶化，导致电化学装置的综合性能下降。
发明内容
本申请的目的在于提供一种正极活性材料、包含该正极活性材料的电化学装置和电子装置，以提高电化学装置的综合性能。
本申请的第一方面提供一种正极活性材料，包括Mn元素和Al元素，正极活性材料颗粒包括靠近所述正极活性材料颗粒表面的第一区域和远离所述正极活性材料颗粒表面的第二区域，第一区域中Al/Mn的摩尔比为a1，第二区域中Al/Mn的摩尔比为a2，满足1.1≤a1/a2≤100，优选地5≤a1/a2≤90。a1/a2的值可以为1.1、5、10、20、30、40、50、60、70、80、90、100或为其间的任意范围。其中，第一区域是指正极活性材料颗粒中用2.4mol/L硫酸酸洗6h后被溶解的部分，第二区域是指正极活性材料颗粒中用2.4mol/L硫酸酸洗6h后未被溶解的部分。
本申请的发明人发现，通过调控第一区域中Al/Mn的摩尔比a1与第二区域中Al/Mn的摩尔比a2的比值a1/a2在上述范围内，使得正极活性材料中的Al富集在靠近正极活性材料表面的区域，不仅能够有效改善正极的锰溶出现象来提高电化学装置的循环性能和存储性能，同时可以减少Al在正极活性材料中的总含量以使正极保持较高的比容量，从而提高电化学装置的综合性能。
具体地，当a1/a2的值过小时(例如小于1.1)，说明第一区域和第二区域中Al/Mn的摩尔比相当，或者第一区域中Al/Mn的摩尔比小于第二区域，也即正极活性材料中的Al主要富集在正极活性材料颗粒的内部，从而对正极的锰溶出现象改善不明显，不利于提高电化学装置的循环性能和存储性能。随着a1/a2的值逐渐增加，得到的正极活性材料中的Al主要富集在正极活性材料颗粒的表面，有利于在改善正极锰溶出的同时保持正极的比容量。但当a1/a2的值过大时(例如大于100)，也即第一区域中Al/Mn的摩尔比a1过大，导致正极活性材料中总的Al含量增大，会降低正极的比容量。通过调控a1/a2的值在上述范围内，有利于同时提高电化学装置的循环性能和存储性能，并使正极保持较高的比容量，从而提高电化学装置的综合性能。
在本申请的一些实施方案中，基于正极活性材料的质量，第一区域中Al的质量百分含量为0.01％至0.5％。例如，第一区域中Al的质量百分含量可以为0.01％、0.05％、0.1％、0.2％、0.3％、0.4％、0.5％或为其间的任意范围。通过调控第一区域中Al的质量百分含量在上述范围内，有利于在改善正极锰溶出的同时使正极保持较高的比容量，从而提高电化学装置的综合性能。
在本申请的一些实施方案中，正极活性材料选自包括Al元素的锰酸锂(LMO)。
在本申请的一些实施方案中，第一区域中Al/Mn的摩尔比a1为1％至30％，优选为5％至30％，和/或第二区域中Al/Mn的摩尔比a2为0.05％至5％。例如，第一区域中Al/Mn的摩尔比a1可以为1％、5％、10％、15％、20％、25％、30％或为其间的任意范围。例如，第二区域中Al/Mn的摩尔比a2可以为0.05％、0.1％、0.2％、0.3％、0.4％、0.5％或为其间的任意范围。
当第一区域中Al/Mn的摩尔比a1过小时(例如小于1％)，不仅不能改善正极的锰溶出现象以提高电化学装置的循环性能和存储性能，而且Al的引入会在一定程度上降低正极的比容量。当第一区域中Al/Mn的摩尔比a1过大时(例如大于30％)，正极活性材料中总的Al含量增大，会降低正极的比容量。当第二区域中Al/Mn的摩尔比a2过小(例如小于0.05％)或过大(例如大于0.5％)时，均不利于改善电化学装置的循环性能和存储性能。通过调控当第一区域中Al/Mn的摩尔比a1和/或第二区域中Al/Mn的摩尔比a2在本申请的范围内，有利于同时提高电化学装置的循环性能和存储性能，并使正极保持较高的比容量，从而提高电化学装置的综合性能。
在本申请的一些实施方案中，正极活性材料满足条件(a)至(c)中的至少一者：(a) 正极活性材料中Al/Mn的摩尔比为0.1％至10％，优选为2％至10％；(b)Mn元素包括Mn 3+和Mn 4+，第一区域中Mn 3+/Mn 4+的摩尔比与第二区域中Mn 3+/Mn 4+的摩尔比的比值e为0.8至0.95；(c)正极活性材料还包括Li，第一区域中Li/Mn的摩尔比为b1，第二区域中Li/Mn的摩尔比为b2，满足1≤b1/b2≤2，优选为1.1≤b1/b2≤2。例如，正极活性材料中Al/Mn的摩尔比可以为0.1％、0.5％、1％、2％、3％、4％、5％、6％、7％、8％、9％、10％或为其间的任意范围。例如，e的值可以为0.8、0.83、0.85、0.87、0.9、0.92、0.95或为其间的任意范围。例如，b1/b2的值可以为1、1.1、1.2、1.4、1.6、1.8、2或为其间的任意范围。
当正极活性材料中Al/Mn的摩尔比过小时(例如小于0.1％)，对正极的锰溶出现象改善不明显，从而对电化学装置的循环性能和存储性能改善不明显。当正极活性材料中Al/Mn的摩尔比过大时(例如大于10％)，导致正极的比容量降低。通过调控正极活性材料中Al/Mn的摩尔比在上述范围内，有利于提高电化学装置的循环性能和存储性能，并使正极保持较高的比容量，从而提高电化学装置的综合性能。
在本申请的一些实施方案中，基于正极活性材料的质量，Al的质量百分含量为0.005％至0.1％。例如，正极活性材料中Al的质量百分含量可以为0.005％、0.01％、0.02％、0.05％、0.08％、0.1％或为其间的任意范围。通过调控正极活性材料中Al的质量百分含量在上述范围内，有利于在改善正极锰溶出的同时使正极保持较高的比容量，从而提高电化学装置的综合性能。
在本申请的一些实施方案中，基于正极活性材料的质量，Mn的质量百分含量为1.0％至1.2％。通过调控正极活性材料中Mn的质量百分含量在上述范围内，有利于在改善正极锰溶出的同时使正极保持较高的比容量，从而提高电化学装置的综合性能。
第一区域中Mn 3+/Mn 4+的摩尔比与第二区域中Mn 3+/Mn 4+的摩尔比的比值e在本申请的范围内，有利于改善锰溶出现象，从而提高电化学装置的循环性能和存储性能。本申请对第一区域中Mn 3+/Mn 4+的摩尔比和第二区域中Mn 3+/Mn 4+的摩尔比没有特别限制，只要满足e的范围即可，例如，第一区域中Mn 3+/Mn 4+的摩尔比为15％至55％，第二区域中Mn 3+/Mn 4+的摩尔比为30％至70％。
第一区域中Li/Mn的摩尔比b1与第二区域中Li/Mn的摩尔比b2的比值b1/b2在上述范围内，使得第一区域中Li/Mn的摩尔比b1大于第二区域中Li/Mn的摩尔比b2，有利于提高电化学装置的循环性能并使正极保持较高的比容量。
在本申请的一些实施方案中，第一区域中Li/Mn的摩尔比b1为58％至98％，第二区域中Li/Mn的摩尔比b2为55％至60％。例如，第一区域中Li/Mn的摩尔比b1可以为58％、60％、65％、70％、75％、80％、85％、90％、95％、98％或为其间的任意范围，第二区域中Li/Mn的摩尔比b2可以为55％、55.5％、56％、56.5％、57％、57.5％、58％、58.5％、59％、59.5％、60％或为其间的任意范围。通过调控第一区域中Li/Mn的摩尔比b1和第二区域中Li/Mn的摩尔比b2在上述范围内，有利于提高电化学装置的循环性能并使正极保持较高的比容量。
在本申请的一些实施方案中，正极活性材料还包括M1元素，M1元素包括Ni、Co、Nb、Mo、V、W、Zr、Mg、Ti、La、Y或B元素中的至少一种，正极活性材料满足以下条件(d)至(e)中的至少一者：(d)M1/Mn的摩尔比为0.1％至5％；(e)Al/M1的摩尔比为1至10。例如，M1/Mn的摩尔比可以为0.1％、0.5％、1％、1.5％、2％、2.5％、3％、3.5％、4％、4.5％、5％或为其间的任意范围。例如，Al/M1的摩尔比可以为1、1.5、2、2.5、3、3.5、4、4.5、5、6、7、8、9、10或为其间的任意范围。
正极活性材料中包括M1元素，且M1/Mn的摩尔比和/或Al/M1的摩尔比在上述范围内，有利于提高电化学装置的存储性能并使正极保持较高的比容量。
在本申请的一些实施方案中，正极活性材料还包括M2元素，M2元素包括F和/或S，基于正极活性材料的质量，M2元素的质量百分含量为0.1％至2％。例如，M2元素的质量百分含量可以为0.1％、0.3％、0.5％、0.8％、1％、1.2％、1.5％、1.8％、2％或为其间的任意范围。
当M2元素的质量百分含量过低时(例如低于0.1％)，对电化学装置的性能改善不明显。随着M2元素的质量百分含量增加，有利于提高正极的比容量。但当M2元素的质量百分含量过高时(例如高于2％)，会恶化电化学装置的循环性能。通过调控M2元素的质量百分含量在上述范围内，有利于提高电化学装置的循环性能，并使正极保持较高的比容量。
在本申请的一些实施方案中，M2元素包括F元素，第一区域中F/Mn的摩尔比为d1，第二区域中F/Mn的摩尔比为d2，满足3≤d1/d2≤50，优选为3≤d1/d2≤25。例如，d1/d2的值可以为3、5、10、15、20、25、30、35、40、45、50或为其间的任意范围。
在正极活性材料中引入M2元素，能够提高电化学装置的循环性能，但是过量的M2元素会影响正极的比容量。通过调控d1/d2的值在本申请的范围内，使第一区域中F/Mn 的摩尔比d1大于第二区域中F/Mn的摩尔比d2，也即，使F元素富集在靠近正极活性材料表面的区域，从而可以在改善电化学装置循环性能的同时，使正极保持较高的比容量。本申请对第一区域中F/Mn的摩尔比d1和第二区域中F/Mn的摩尔比d2没有特别限制，只要满足d1/d2的范围即可，例如，第一区域中F/Mn的摩尔比d1为1％至2.5％，第二区域中F/Mn的摩尔比d2为0.05％至0.5％。
在本申请的一些实施方案中，正极活性材料还包括Nb元素，第一区域中Nb/Mn的摩尔比为c1，第二区域中Nb/Mn的摩尔比为c2，满足3≤c1/c2≤50。例如，c1/c2的值可以为3、10、15、20、25、30、35、40、45或为其间的任意范围。
在正极活性材料中引入Nb元素且c1/c2的值在上述范围内，有利于提高电化学装置的循环性能。本申请对第一区域中Nb/Mn的摩尔比c1和第二区域中Nb/Mn的摩尔比为c2没有特别限制，只要满足c1/c2的范围即可，例如，第一区域中Nb/Mn的摩尔比c1为1％至5％，第二区域中Nb/Mn的摩尔比为c2为0.1％至0.8％。
在本申请的一些实施方案中，正极活性材料的Dv99为15μm至50μm，优选为25μm至35μm，正极活性材料的粒径满足条件(ⅰ)至(ⅱ)中的至少一者：(ⅰ)5μm≤Dv90≤30μm，5μm≤Dv99-Dv90≤21μm，优选为8μm≤Dv99-Dv90≤12μm；(ⅱ)2μm≤Dv10≤10μm，1≤(Dv99-Dv10)/Dv50≤4，优选为4μm≤Dv10≤7μm，2≤(Dv99-Dv10)/Dv50≤3。
例如，正极活性材料的Dv99可以为15μm、20μm、25μm、30μm、35μm、40μm、45μm、50μm或为其间的任意范围。例如，正极活性材料的Dv90可以为5μm、8μm、10μm、13μm、15μm、18μm、20μm、23μm、25μm、28μm、30μm或为其间的任意范围，Dv99-Dv90的值可以为5μm、8μm、10μm、12μm、15μm、18μm、20μm、21μm或为其间的任意范围。例如，正极活性材料的Dv10可以为2μm、3μm、4μm、5μm、6μm、7μm、8μm、9μm、10μm或为其间的任意范围，(Dv99-Dv10)/Dv50的值可以为1、1.5、2、2.5、3、3.5、4或为其间的任意范围。
通过调控正极活性材料的Dv99，以及Dv90与Dv99-Dv90的值上述范围内，或者调控正极活性材料的Dv99，以及Dv10与(Dv99-Dv10)/Dv50的值在上述范围内，再或者调控正极活性材料的Dv99、Dv90、Dv99-Dv90的值、Dv10和(Dv99-Dv10)/Dv50的值在上述范围内，均有利于提高电化学装置的综合性能。
本申请对正极活性材料的制备方法没有特别限制，只要能实现本申请的目的即可。例如，正极活性材料的制备方法可以包括但不限于以下步骤：将原料混合在T1温度下进行 第一次煅烧，煅烧时间为t1，得到中间产物；然后加入中间原料与中间产物进行混合，在T2温度下进行第二次煅烧，煅烧时间为t2，得到正极活性材料。
本申请对第一次煅烧的温度T1和煅烧时间t1，以及第二次煅烧的温度T2和煅烧时间t2没有特别限制，只要能实现本申请的目的即可，例如，T1为800℃至900℃，t1为35h至45h，T2为450℃至600℃，t2为5h至15h。
本申请对上述原料和中间原料没有特别限制，只要能实现本申请的目的即可，例如，原料和中间原料可以各自独立地包括但不限于MnO 2、Li 2CO 3或Al 2O 3中的至少一种。
煅烧温度和煅烧时间通常会影响正极活性材料中的元素在正极活性材料颗粒中的分布，例如，煅烧温度降低和/或煅烧时间缩短，会使得元素分布在靠近正极活性材料颗粒表面的区域，例如，本申请的第一区域；煅烧温度升高和/或煅烧时间延长，会使得元素分布在远离正极活性材料颗粒表面的区域，例如，本申请的第二区域。
在本申请中，对于在正极活性材料中引入元素M1的方法没有特别限制，只要能实现本申请的目的即可，例如在正极活性材料的制备过程中加入含有M1的化合物。本申请对含有M1的化合物没有特别限制，只要能实现本申请的目的即可，例如，可以包括但不限于MgO、乙酸镍、TiO 2、ZrO 2、Nb 2O 5、MoO 3、V 2O 5、WO 3或Y 2O 3中的至少一种。
在本申请中，对于在正极活性材料中引入元素M2的方法没有特别限制，只要能实现本申请的目的即可，例如在正极活性材料的制备过程中加入含有M2的化合物。本申请对含有M2的化合物没有特别限制，只要能实现本申请的目的即可，例如，可以包括但不限于MnS或LiF中的至少一种。
本申请的第二方面提供一种电化学装置，包括正极、负极和电解液，正极包括本申请任一实施方案中的正极活性材料，正极包括正极材料层和正极集流体，正极材料层包括第一正极材料层和第二正极材料层，第一正极材料层位于第二正极材料层和正极集流体之间，第一正极材料层中Mn元素的含量大于第二正极材料层中Mn元素的含量。第一正极材料层中Mn元素的含量大于第二正极材料层中Mn元素的含量有利于减少正极的锰溶出现象，从而提高电化学装置的循环性能和存储性能。
在本申请的一些实施方案中，基于电解液的质量，电解液满足条件(ⅲ)至(ⅴ)中的至少一者：(ⅲ)电解液包括链状碳酸酯，链状碳酸酯的质量百分含量为20％至60％，链状碳酸酯包括碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)或碳酸甲乙酯(EMC)中的至少一种；(ⅳ)电解液包 括含苯化合物，含苯化合物的质量百分含量为0.01％至5％，优选为0.01％至3％，进一步优选为1％至3％，含苯化合物包括联苯(BP)、氟苯(FP)或环己基苯(CHB)中的至少一种；(ⅴ)电解液包括聚苯乙烯(PS)，聚苯乙烯的质量百分含量为0.01％至5％，优选为0.01％至3％。
例如，链状碳酸酯的质量百分含量可以为20％、25％、30％、35％、40％、45％、50％、55％、60％或为其间的任意范围。例如，含苯化合物的质量百分含量可以为0.01％、0.05％、0.1％、1％、2％、3％、4％、5％或为其间的任意范围。例如，聚苯乙烯的质量百分含量可以为0.01％、0.05％、0.1％、1％、2％、3％、4％、5％或为其间的任意范围。在电解液中可选地加入链状碳酸酯、含苯化合物或聚苯乙烯中的至少一种，且其质量百分含量在上述范围内，有利于正极活性材料与电解液之间形成协同作用，从而提高电化学装置的循环性能和存储性能。
在本申请的一些实施方案中，负极包括负极材料层，负极材料层包括负极活性材料，负极活性材料包括天然石墨、人造石墨或硬碳中的至少一种，电化学装置满足条件(ⅵ)至(ⅸ)中的至少一者：(ⅵ)负极活性材料的2μm≤Dv10≤10μm，优选为3μm≤Dv10≤8μm；(ⅶ)负极活性材料的5μm≤Dv90≤20μm，5μm≤Dv99-Dv90≤25μm，优选为5μm≤Dv90≤15μm，5μm≤Dv99-Dv90≤10μm；(ⅷ)负极活性材料的晶向指数(OI)的值为5至30，优选为8至20；(ⅸ)负极活性材料的石墨化度为92％至96％，优选为93％至95％。
例如，负极活性材料的Dv10可以为2μm、3μm、4μm、5μm、6μm、7μm、8μm、9μm、10μm或为其间的任意范围。例如，负极活性材料的Dv90可以为5μm、8μm、10μm、13μm、15μm、18μm、20μm或为其间的任意范围，Dv99-Dv90的值可以为5μm、8μm、10μm、13μm、15μm、18μm、20μm、23μm、25μm或为其间的任意范围。例如，负极活性材料的OI的值可以为5、8、10、13、15、18、20、23、25、28、30或为其间的任意范围。例如，负极活性材料的石墨化度可以为92％、93％、94％、95％、96％或为其间的任意范围。
通过调整负极活性材料的Dv10、负极活性材料的Dv10、Dv90和Dv99-Dv90的值、负极活性材料的OI的值或负极活性材料石墨化度中的至少一个在本申请的范围内，有利于负极活性材料、正极活性材料和电解液之间形成协同作用，有利于提高电化学装置的循环性能和存储性能。
在本申请的一些实施方案中，电化学装置包括隔离膜，隔离膜通过差示扫描量热法(DSC)测试的起始放热温度为138℃至145℃，优选为141℃至143℃，进一步优选为141℃ 至142℃。例如，隔离膜通过差示扫描量热法测试的起始放热温度为138℃、139℃、140℃、141℃、142℃、143℃、144℃、145℃或为其间的任意范围。通过调控隔离膜通过DSC测试的起始放热温度在本申请的范围内，有利于隔离膜与负极活性材料、正极活性材料和电解液之间形成协同作用，有利于提高电化学装置的循环性能和存储性能。
在本申请中，正极活性材料中的不同元素的摩尔比是将含有该正极活性材料的电化学装置在0％的荷电状态下，拆解得到正极，然后测试得到不同元素的含量计算得到。
在本申请中，正极集流体没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于铝箔、铝合金箔或复合集流体等。在本申请中，对正极集流体的厚度没有特别限制，只要能够实现本申请目的即可，例如厚度为8μm至12μm。
在本申请中，正极材料层中包括本申请前述任一实施方案中的正极活性材料，正极材料层还可以包括粘结剂，本申请对粘结剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于聚丙烯酸、聚丙烯酸钠、聚丙烯酸钾、聚丙烯酸锂、聚酰亚胺、聚乙烯醇、羧甲基纤维素、羧甲基纤维素钠、聚酰亚胺、聚酰胺酰亚胺、丁苯橡胶或聚偏氟乙烯中的至少一种。
在本申请中，正极材料层中还可以导电剂，本申请对导电剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于导电炭黑(Super P)、碳纳米管(CNTs)、碳纤维、鳞片石墨、科琴黑、石墨烯、金属材料或导电聚合物中的至少一种。上述碳纳米管可以包括但不限于单壁碳纳米管和/或多壁碳纳米管。上述碳纤维可以包括但不限于气相生长碳纤维(VGCF)和/或纳米碳纤维。上述金属材料可以包括但不限于金属粉和/或金属纤维，具体地，金属可以包括但不限于铜、镍、铝或银中的至少一种。上述导电聚合物可以包括但不限于聚亚苯基衍生物、聚苯胺、聚噻吩、聚乙炔或聚吡咯中的至少一种。
任选地，正极还可以包括导电层，导电层位于正极集流体和正极材料层之间。本申请对导电层的组成没有特别限制，可以是本领域常用的导电层，例如可以包括但不限于上述导电剂和上述粘结剂。
在本申请中，负极可以包括负极集流体，本申请负极集流体没有特别限制，只要能够实现本申请目的即可，可以包括但不限于铜箔、铜合金箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜或复合集流体等。在本申请中，对负极的集流体的厚度没有特别限制，只要能够实现本申请目的即可，例如厚度为4μm至12μm。在本申请中，负极材料层可以设置于负极集流体厚度方向上的一个表面上，也可以设置于负极集流体厚度方向上的两个表面上。 需要说明，这里的“表面”可以是负极集流体的全部区域，也可以是负极集流体的部分区域，本申请没有特别限制，只要能实现本申请目的即可。
在本申请中，负极材料层中还可以包括导电剂，本申请对导电剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于上述导电剂中的至少一种。
在本申请中，负极材料层中还可以包括粘结剂，本申请对粘结剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于上述粘结剂中的至少一种。
任选地，负极还可以包括导电层，导电层位于负极集流体和负极材料层之间。本申请对导电层的组成没有特别限制，可以是本领域常用的导电层，导电层可以包括但不限于上述导电剂和上述粘结剂。
本申请对隔离膜没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于聚乙烯(PE)、聚丙烯(PP)、聚四氟乙烯为主的聚烯烃(PO)类隔膜、聚酯膜(例如聚对苯二甲酸二乙酯(PET)膜)、纤维素膜、聚酰亚胺膜(PI)、聚酰胺膜(PA)、氨纶、芳纶膜、织造膜、非织造膜(无纺布)、微孔膜、复合膜、隔膜纸、碾压膜或纺丝膜等中的至少一种，优选为PP。本申请的隔离膜可以具有多孔结构，孔径的尺寸没有特别限制，只要能实现本申请的目的即可，例如，孔径的尺寸可以为0.01μm至1μm。在本申请中，隔离膜的厚度没有特别限制，只要能实现本申请的目的即可，例如厚度可以为5μm至500μm，优选为25μm。
例如，隔离膜可以包括基材层和表面处理层。基材层可以为具有多孔结构的无纺布、膜或复合膜，基材层的材料可以包括但不限于聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯或聚酰亚胺等中的至少一种。任选地，可以使用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。任选地，基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。
无机物层可以包括但不限于无机颗粒和粘结剂，本申请对无机颗粒没有特别限制，例如，可以包括但不限于氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡等中的至少一种。本申请对粘结剂没有特别限制，例如，可以包括但不限于聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯或聚六氟丙烯 中的至少一种。聚合物层中包含聚合物，聚合物的材料可以包括但不限于聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚偏氟乙烯或聚(偏氟乙烯-六氟丙烯)等中的至少一种。
在本申请中，电解液中还可以包括锂盐，本申请对锂盐没有特别限制，只要能实现本申请的目的即可，例如可以包括但不限于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或二氟硼酸锂中的至少一种。优选地，锂盐包括LiPF 6。
在本申请中，电解液中还可以包括非水溶剂，本申请对非水溶剂没有特别限制，只要能实现本申请的目的即可，例如可以包括但不限于碳酸酯化合物、羧酸酯化合物、醚化合物或其它有机溶剂中的至少一种。上述碳酸酯化合物可以包括但不限于环状碳酸酯化合物和/或氟代碳酸酯化合物中的至少一种。上述环状碳酸酯可以包括但不限于碳酸乙烯酯(也称碳酸亚乙酯，简称为EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)或碳酸乙烯基亚乙酯(VEC)中的至少一种。氟代碳酸酯化合物可以包括但不限于氟代碳酸乙烯酯(也称氟代碳酸亚乙酯，简称为FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯或碳酸三氟甲基亚乙酯中的至少一种。上述羧酸酯化合物可以包括但不限于甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、γ-丁内酯、癸内酯、戊内酯、甲瓦龙酸内酯或己内酯中的至少一种。上述醚化合物可以包括但不限于二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、乙氧基甲氧基乙烷、2-甲基四氢呋喃或四氢呋喃中的至少一种。上述其它有机溶剂可以包括但不限于二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、甲酰胺、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯、磷酸三辛酯或磷酸酯中的至少一种。基于电解液的质量，上述非水溶剂的质量百分含量为15％至80％，例如可以15％、20％、30％、40％、50％、60％、70％、80％或为其间的任意范围。
本申请的电化学装置没有特别限制，其可以包括发生电化学反应的任何装置。在一些实施方案中，电化学装置可以包括但不限于：锂金属二次电池、锂离子二次电池(锂离子电池)、锂聚合物二次电池或锂离子聚合物二次电池等。
电化学装置的制备过程为本领域技术人员所熟知的，本申请没有特别的限制，例如， 可以包括但不限于以下步骤：将正极、隔离膜和负极按顺序堆叠，并根据需要将其卷绕、折叠等操作得到卷绕结构的电极组件，将电极组件放入包装袋内，将电解液注入包装袋并封口，得到电化学装置；或者，将正极、隔离膜和负极按顺序堆叠，然后用胶带将整个叠片结构的四个角固定好得到叠片结构的电极组件，将电极组件置入包装袋内，将电解液注入包装袋并封口，得到电化学装置。此外，也可以根据需要将防过电流元件、导板等置于包装袋中，从而防止电化学装置内部的压力上升、过充放电。
本申请的第三方面提供了一种电子装置，包含本申请前述任一实施方案中的电化学装置。本申请提供的电化学装置具有良好的循环性能和存储性能、正极具有较高的比容量，从而本申请提供的电子装置具有较长的使用寿命和良好的性能。
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。
本申请提供了一种正极活性材料，包括Mn元素和Al元素，正极活性材料颗粒包括靠近正极活性材料颗粒表面的第一区域和远离正极活性材料颗粒表面的第二区域，第一区域中Al/Mn的摩尔比为a1，第二区域中Al/Mn的摩尔比为a2，满足1.1≤a1/a2≤100。通过调控第一区域中Al/Mn的摩尔比a1，以及第一区域中Al/Mn的摩尔比a1与第二区域中Al/Mn的摩尔比a2的比值a1/a2在上述范围内，使得正极活性材料中的Al富集在靠近正极活性材料表面的区域，不仅能够有效改善正极的锰溶出现象来提高电化学装置的循环性能和存储性能，同时可以减少Al在正极活性材料中的总含量以使正极保持较高的比容量，从而提高电化学装置的综合性能。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面对实施例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，对于本领域普通技术人员来讲，还可以根据这些附图获得其他的实施例。
图1为本申请一些实施例中的正极活性材料颗粒的剖面示意图；
附图标记：10、正极活性材料，11、第一区域，12、第二区域。
具体实施方式
为使本申请的目的、技术方案、及优点更加清楚明白，以下参照附图并举实施例，对本申请进一步详细说明。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员所获得的所有其他实施例，都属于本申请保护的范围。
图1示出了本申请一些实施例中的正极活性材料颗粒的剖面示意图，可以看出，第一区域11为靠近正极活性材料10的颗粒的表面的区域，第二区域12为远离正极活性材料10颗粒的表面的区域。
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。
实施例
以下，举出实施例及对比例来对本申请的实施方式进行更具体地说明。各种的试验及评价按照下述的方法进行。另外，只要无特别说明，“％”为质量基准。
测试方法和设备：
元素的含量测试：
a)配置硫酸溶液，浓度为2.4mol/L；
b)取正极活性材料50g(将锂离子电池满放至2.5V，用陶瓷小刀将正极上的正极材料层刮下，将正极活性材料层在400℃下煅烧5h，得到正极活性材料)；
c)将300mL硫酸溶液和50g正极活性材料混合，放置在磁力搅拌器上进行搅拌，搅拌速度固定为200r/min；
d)在经过6h后停止搅拌并静置，静置4h后用滤纸抽滤；保留滤液，使用电感耦合等离子体发射光谱仪(型号为Thermo ICAP6300)进行测试，可以计算得到第一区域中不同元素之间的摩尔比，例如Al/Mn的摩尔比、Li/Mn的摩尔比、Nb/Mn的摩尔比和F/Mn的摩尔比等；
e)对抽滤后的样品在85℃烘干8h；
f)干燥后的样品使用电感耦合等离子体发射光谱仪(型号为Thermo ICAP6300)进行测试，可以计算得到第二区域中不同元素之间的摩尔比，例如Al/Mn的摩尔比、Li/Mn的摩尔比、Nb/Mn的摩尔比和F/Mn的摩尔比等。
Mn 3+/Mn 4+摩尔比测试：
采用X射线光电子能谱(XPS)测试分析正极活性材料第一区域和第二区域的Mn 3+/Mn 4+摩尔比。
循环性能测试：
在25℃条件下，将锂离子电池以0.5C恒流充电至4.2V，再在4.2V条件下恒压充电至0.05C，然后以1C的恒电流放电至2.8V，记录放电容量为D 01；按照上述操作步骤使锂离子电池进行多次“0.5C充电-1C放电”的循环流程，循环500圈，测试第500次循环后的放电容量为D 1。25℃循环500圈后的容量保持率(％)＝D 1/D 01×100％。
存储性能测试：
将锂离子电池在25℃的环境中静置30min，然后以0.2C倍率恒流充电至4.2V，再以4.2V恒压充电至0.05C，静置30min，然后以0.5C倍率放电至2.8V，记录此时的放电容量为锂离子电池存储前容量；然后将满充状态的电池置于约60℃烘箱存储约7天后，测试其存储后容量。具体测试流程如下：将锂离子电池在25℃的环境中静置30min，然后以0.2C倍率恒流充电至4.2V，以4.2V恒压充电至0.05C，静置30min，然后以0.5C倍率放电至2.8V，记录此时的放电容量为锂离子电池的存储后容量。
60℃高温存储容量保持率＝存储后容量/存储前容量×100％。
每个实施例或对比例测试4个锂离子电池，取平均值为最终结果。
比容量测试：
采用实施例或对比例中的正极和锂金属制作扣式电池，在25℃的环境中，将扣式电池以0.5C(即，2h内完全放掉理论容量的电流值)的充电电流下进行恒流和恒压充电，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，记录首次放电容量。首次放电容量与正极的质量的比值记为正极的比容量。每个实施例或对比例测试4个正极，取平均值为最终结果。其中，正极的质量为减去正极集流体后的质量。其中，扣式电池的制备方法采用本领域已知的制备方法进行制备，扣式电池中的电解液为各实施例或对比例中所用的电解液。
隔离膜的起始放热温度测试：
采用DSC进行测试，以10℃/min的升温速率，得到隔离膜的DSC曲线，从DSC曲线中可得到隔离膜的起始放热温度。
粒径的测试方法：
利用激光粒度仪(型号：Mastersize3000)测试正极活性材料或负极活性材料的粒度。Dv10、Dv50、Dv90、Dv99分别为颗粒采用激光散射粒度仪测试得到的体积基准分布中累计10％、50％、90％、99％的直径。
实施例1-1
<正极活性材料的制备>
一次煅烧：将原料MnO 2、Al 2O 3和Li 2CO 3按照Al/Mn摩尔比为x1和Li/Mn摩尔比为y1进行混合，在温度T1下煅烧，煅烧时间t1，得到中间产物；
二次煅烧：再将Al 2O 3、Li 2CO 3和中间产物进行混合，在温度T2下煅烧，煅烧时间t2，得到正极活性材料为包括Al元素的锰酸锂(LMO)。
其中，二次煅烧时加入的Al 2O 3中的Al与中间产物中的Mn的Al/Mn摩尔比为x2，二次煅烧时加入的Li 2CO 3中的Li与中间产物中的Mn的Li/Mn摩尔比为y2；原料MnO 2中含Al且Al/Mn摩尔比为x0。正极活性材料的Dv99为45μm，Dv90为26μm，Dv50为11.2μm，Dv10为6μm。
<正极的制备>
将上述制备得到的正极活性材料、导电剂乙炔黑、粘结剂聚偏二氟乙烯按照质量比为96.5:2:1.5进行混合，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70wt％。将正极浆料均匀涂覆于厚度为12μm的正极集流体铝箔的一个表面上，将铝箔在120℃下烘干处理1h，得到单面涂覆有正极材料层的正极。在铝箔的另一个表面上重复以上步骤，即得到双面涂布正极材料层的正极。然后经过冷压、裁片、分切后，在120℃的真空条件下干燥1h，得到规格为74mm×867mm的正极。
<负极的制备>
将负极活性材料人造石墨、导电剂乙炔黑、粘结剂丁苯橡胶(SBR)、增稠剂羧甲基纤维素钠(CMC)按照质量比为95:2:2:1进行混合，加入去离子水，在真空搅拌机作用下搅拌均匀，获得负极浆料，其中负极浆料的固含量为75wt％。将负极浆料均匀涂覆于厚度为12μm的负极集流体铜箔的一个表面上，将铜箔在120℃下烘干，得到涂层厚度为130μm的单面涂覆有负极材料层的负极。在铝箔的另一个表面上重复以上步骤，即得到双面涂布负极活性材料层的负极。然后经过冷压、裁片、分切后，在120℃的真空条件下干燥1h，得到规格为78mm×875mm的负极。其中，负极活性材料的Dv99为30μm，Dv90为18μm，Dv10为5μm，OI的值为18，石墨化度为96％。
<电解液的制备>
在干燥的氩气气氛手套箱中，将EC、PC、DEC、EMC按照质量比为5:1:4:7混合得到有机溶剂，然后向有机溶剂中加入锂盐LiPF 6溶解并混合均匀，得到电解液。其中，LiPF 6在电解液中的质量百分含量为12.5％，其余为有机溶剂。
<隔离膜的制备>
采用厚度为7μm的多孔聚乙烯薄膜(Celgard公司提供)，隔离膜的起始放热温度为141℃。
<锂离子电池的制备>
将上述制备得到的正极、隔离膜、负极按顺序叠好，使隔离膜处于正极和负极中间起到隔离的作用，卷绕得到电极组件。将电极组件置于铝塑膜包装袋中，干燥后注入电解液，经过真空封装、静置、化成、脱气、切边等工序得到锂离子电池。
实施例1-2至实施例1-8
除了按照表1调整相关制备参数以外，其余与实施例1-1相同。
实施例2-1至实施例2-4
除了按照表2调整相关制备参数以外，其余与实施例1-4相同。
实施例3-1至实施例3-5、实施例3-7和实施例3-8
除了在<正极活性材料的制备>中，在一次煅烧时调整加入M1元素对应的化合物及其含量，制得各元素摩尔比如表3所示的正极活性材料以外，其余与实施例1-4相同。
实施例3-6
除了在<正极活性材料的制备>中，在一次煅烧时加入M1元素对应的化合物、使得M1/Mn摩尔比为1.0％；在二次煅烧时加入M1元素对应的化合物、使得M1与中间产物中的Mn摩尔比为2.6％，制得各元素摩尔比如表3所示的正极活性材料以外，其余与实施例1-4相同。
实施例3-9
除了在<正极活性材料的制备>中，在一次煅烧时调整加入M1元素对应的化合物及其含量、使得M1/Mn摩尔比为1.0％；在二次煅烧时加入M1元素对应的化合物、使得M1与中间产物中的Mn摩尔比为1.0％，制得各元素摩尔比如表3所示的正极活性材料以外，其余与实施例1-4相同。
实施例3-10至实施例3-13
除了在一次煅烧时加入M2对应的化合物、使得M2元素的质量百分含量如表3所示以外，其余与实施例1-4相同。
实施例3-14
除了在一次煅烧时加入M2对应的化合物、使得M2元素的质量百分含量如表3所示以外，其余与实施例3-7相同。
实施例4-1至实施例4-3
除了按照表4调整相关制备参数以外，其余与实施例1-4相同。
实施例5-1至实施例5-6
除了在制备电解液时按照表5加入含苯化合物和PS，并调整相关制备参数以外，其余与实施例1-4相同。
对比例1-1和对比例1-2
除了按照表1调整相关制备参数以外，其余与实施例1-4相同。
各实施例和对比例的相关制备参数及性能测试如表1至表5所示。
表1
Figure PCTCN2022074938-appb-000001
从实施例1-1至实施例1-8、对比例1-1至对比例1-2可以看出，当正极活性材料的第一区域中Al/Mn的摩尔比a1与第二区域中Al/Mn的摩尔比a2的比值a1/a2在本申请的范围内，能够同时提高电化学装置中正极的比容量、电化学装置的循环性能和存储性能。同时，当e的值在本申请的范围内，得到的电化学装置同时具有良好的循环性能和存储性能，电化学装置中的正极也具有较高的比容量。从实施例1-1至实施例1-8、对比例1-1可以看出，当第一区域中Al/Mn的摩尔比a1在本申请的范围内，得到的电化学装置同时具有良好的循环性能和存储性能，电化学装置中的正极也具有较高的比容量。从实施例1-1至实 施例1-8可以看出，当第二区域中Al/Mn的摩尔比a2和正极活性材料的Al/Mn摩尔比在本申请的范围内，得到的电化学装置同时具有良好的循环性能和存储性能，电化学装置中的正极也具有较高的比容量。
表2
Figure PCTCN2022074938-appb-000002
从实施例1-4、实施例2-1至实施例2-4可以看出，当正极活性材料的第一区域中Li/Mn的摩尔比b1与第二区域中Li/Mn的摩尔比b2的比值b1/b2在本申请的范围内，得到的电化学装置同时具有良好的循环性能和存储性能，电化学装置中的正极也具有较高的比容量。随着b1/b2的值增大，电化学装置的循环性能和存储性能呈现逐渐上升的趋势。
表3
Figure PCTCN2022074938-appb-000003
Figure PCTCN2022074938-appb-000004
注：表3中的实施例，在制备正极活性材料时，Mg对应的化合物是MgO，Ni对应的化合物是乙酸镍，Ti对应的化合物是TiO 2，Zr对应的化合物是ZrO 2，Nb对应的化合物是Nb 2O 5，S对应的化合物为MnS，F对应的化合物为LiF；表3中的“/”表示不存在对应的制备参数或物质。
从实施例1-4、实施例3-1至实施例3-14可以看出，M1元素和/或M2元素的加入能够进一步提高电化学装置的循环性能和存储性能、以及电化学装置中正极的比容量。从实施例3-1至实施例3-9可以看出，当在正极活性材料中引入本申请范围内的M1元素，且M1/Mn摩尔比、Al/M1摩尔比、c1/c2的值在本申请的范围内，得到的电化学装置同时具有良好的循环性能和存储性能，电化学装置中的正极也具有较高的比容量。从实施例3-10至实施例3-13可以看出，当在正极活性材料中引入本申请范围内的M2元素，且M2元素的质量百分含量、d1/d2的值在本申请的范围内，得到的电化学装置同时具有良好的循环性能和存储性能，电化学装置中的正极也具有较高的比容量。从实施例1-4和实施例3-14可以看出，M1元素和M2元素同时引入能够进一步提高电化学装置的循环性能和存储性能、以及电化学装置中正极的比容量。
表4
Figure PCTCN2022074938-appb-000005
正极活性材料的粒径通常会影响电化学装置的性能，例如，循环性能和存储性能。从
实施例1-4、实施例4-1至实施例4-3可以看出，当正极活性材料的Dv90、Dv10、Dv99-Dv90的值、(Dv99-Dv10)/Dv50的值在本申请的范围内，得到的电化学装置同时具有良好的循环性能和存储性能，电化学装置中的正极也具有较高的比容量。
表5
Figure PCTCN2022074938-appb-000006
注：表5的“/”表示不存在对应的制备参数或物质。
电化学装置电解液中组分的种类及其含量通常会影响电化学装置的性能，例如循环性能和存储性能。从实施例1-4、实施例5-1至实施例5-3可以看出，当电解液中包括含苯化合物且其种类和质量百分含量在本申请的范围内，得到的电化学装置同时具有更好的循环性能和存储性能。从实施例1-4、实施例5-4和实施例5-5可以看出，当电解液中包括PS且其质量百分含量在本申请的范围内，得到的电化学装置同时具有更好的循环性能和存储性能。从实施例1-4和实施例5-6可以看出，含苯化合物和PS具有良好的叠加性，可以进一步提升电化学装置的循环性能和存储性能。
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 (17)

  1. 一种正极活性材料，其包括Mn元素和Al元素，正极活性材料颗粒包括靠近所述正极活性材料颗粒表面的第一区域和远离所述正极活性材料颗粒表面的第二区域，所述第一区域中Al/Mn的摩尔比为a1，所述第二区域中Al/Mn的摩尔比为a2，满足1.1≤a1/a2≤100。
  2. 根据权利要求1所述的正极活性材料，其中，a1为1％至30％，和/或a2为0.05％至5％。
  3. 根据权利要求1所述的正极活性材料，其中，基于所述正极活性材料的质量，所述第一区域中Al的质量百分含量为0.01％至0.5％。
  4. 根据权利要求1所述的正极活性材料，其中，正极活性材料选自包括Al元素的锰酸锂。
  5. 根据权利要求1所述的正极活性材料，其满足以下条件(a)至(c)中的至少一者：
    (a)所述正极活性材料中Al/Mn的摩尔比为0.1％至10％；
    (b)Mn元素包括Mn 3+和Mn 4+，所述第一区域中Mn 3+/Mn 4+的摩尔比与所述第二区域中Mn 3+/Mn 4+的摩尔比的比值e为0.80至0.95；
    (c)所述正极活性材料包括Li，所述第一区域中Li/Mn的摩尔比为b1，所述第二区域中Li/Mn的摩尔比为b2，满足1≤b1/b2≤2。
  6. 根据权利要求1所述的正极活性材料，其还包括M1元素，所述M1元素包括Ni、Co、Nb、Mo、V、W、Zr、Mg、Ti、La、Y或B元素中的至少一种，所述正极活性材料满足以下条件(d)至(e)中的至少一者：
    (d)M1/Mn的摩尔比为0.1％至5％；
    (e)Al/M1的摩尔比为1至10。
  7. 根据权利要求1所述的正极活性材料，其还包括M2元素，所述M2元素包括F和/或S，基于所述正极活性材料的质量，M2元素的质量百分含量为0.1％至2％。
  8. 根据权利要求7所述的正极活性材料，其中，M2元素包括F元素，所述第一区域中F/Mn的摩尔比为d1，所述第二区域中F/Mn的摩尔比为d2，满足3≤d1/d2≤50。
  9. 根据权利要求1所述的正极活性材料，其还包括Nb元素，所述第一区域中Nb/Mn的摩尔比为c1，所述第二区域中Nb/Mn的摩尔比为c2，满足3≤c1/c2≤50。
  10. 根据权利要求1所述的正极活性材料，其中，所述正极活性材料的Dv99为15μm 至50μm，所述正极活性材料的粒径满足以下条件(ⅰ)至(ⅱ)中的至少一者：
    (ⅰ)5μm≤Dv90≤30μm，5μm≤Dv99-Dv90≤21μm；
    (ⅱ)2μm≤Dv10≤10μm，1≤(Dv99-Dv10)/Dv50≤4。
  11. 根据权利要求1至10中任一项所述的正极活性材料，其中所述正极活性材料满足以下至少一者：
    (f)5≤a1/a2≤90；
    (g)所述a1为5％至30％；
    (h)所述正极活性材料中Al/Mn的摩尔比为2％至10％；
    (i)1.1≤b1/b2≤2；
    (j)3≤d1/d2≤25；
    (k)所述正极活性材料的Dv99为25μm至35μm；
    (l)所述正极活性材料的粒径满足8μm≤Dv99-Dv90≤12μm；
    (m)所述正极活性材料的粒径满足4μm≤Dv10≤7μm，2≤(Dv99-Dv10)/Dv50≤3。
  12. 一种电化学装置，包括正极、负极和电解液，所述正极包括权利要求1至11中任一项所述的正极活性材料，所述正极包括正极材料层和正极集流体，所述正极材料层包括第一正极材料层和第二正极材料层，所述第一正极材料层位于所述第二正极材料层和所述正极集流体之间，所述第一正极材料层中Mn元素的含量大于所述第二正极材料层中Mn元素的含量。
  13. 根据权利要求12所述的电化学装置，基于所述电解液的质量，所述电解液满足以下条件(ⅲ)至(ⅴ)中的至少一者：
    (ⅲ)所述电解液包括链状碳酸酯，所述链状碳酸酯的质量百分含量为20％至60％，所述链状碳酸酯包括碳酸二甲酯、碳酸二乙酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯或碳酸甲乙酯中的至少一种；
    (ⅳ)所述电解液包括含苯化合物，所述含苯化合物的质量百分含量为0.01％至5％，所述含苯化合物包括联苯、氟苯或环己基苯中的至少一种；
    (ⅴ)所述电解液包括聚苯乙烯，所述聚苯乙烯的质量百分含量为0.01％至5％。
  14. 根据权利要求13所述的电化学装置，其中所述电化学装置满足以下至少一者：
    (x)基于所述电解液的质量，所述含苯化合物的质量百分含量为1％至3％；
    (xi)基于所述电解液的质量，所述聚苯乙烯的质量百分含量为0.01％至3％。
  15. 根据权利要求12所述的电化学装置，所述负极包括负极材料层，所述负极材料层包括负极活性材料，所述负极活性材料包括天然石墨、人造石墨或硬碳中的至少一种，所述电化学装置满足以下条件(ⅵ)至(ⅸ)中的至少一者：
    (ⅵ)所述负极活性材料的2μm≤Dv10≤10μm；
    (ⅶ)所述负极活性材料的5μm≤Dv90≤20μm，5μm≤Dv99-Dv90≤25μm；
    (ⅷ)所述负极活性材料的晶向指数的值为5至30；
    (ⅸ)所述负极活性材料的石墨化度为92％至96％。
  16. 根据权利要求12所述的电化学装置，所述电化学装置包括隔离膜，所述隔离膜通过差示扫描量热法测试的起始放热温度为138℃至145℃。
  17. 一种电子装置，其包括权利要求12至16中任一项所述的电化学装置。
PCT/CN2022/074938 2022-01-29 2022-01-29 一种正极活性材料、包含该正极活性材料的电化学装置和电子装置 WO2023142029A1 (zh)

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CN102646826A (zh) * 2012-05-21 2012-08-22 甘肃大象能源科技有限公司 一种核-壳型锰酸锂复合正极材料及其制备方法和应用
CN102683667A (zh) * 2011-12-06 2012-09-19 中国科学院宁波材料技术与工程研究所 一种锂锰铝氧正极材料及其制备方法
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JP2010044963A (ja) * 2008-08-13 2010-02-25 Sumitomo Metal Mining Co Ltd 非水系電解質二次電池用正極活物質、その製造方法および非水系電解質二次電池
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