WO2023225796A1 - 正极活性材料、其制备方法、正极极片、二次电池、电池模块、电池包和用电装置 - Google Patents

正极活性材料、其制备方法、正极极片、二次电池、电池模块、电池包和用电装置 Download PDF

Info

Publication number
WO2023225796A1
WO2023225796A1 PCT/CN2022/094485 CN2022094485W WO2023225796A1 WO 2023225796 A1 WO2023225796 A1 WO 2023225796A1 CN 2022094485 W CN2022094485 W CN 2022094485W WO 2023225796 A1 WO2023225796 A1 WO 2023225796A1
Authority
WO
WIPO (PCT)
Prior art keywords
active material
positive electrode
source
mol
group
Prior art date
Application number
PCT/CN2022/094485
Other languages
English (en)
French (fr)
Inventor
袁天赐
蒋耀
张欣欣
欧阳楚英
陈尚栋
吴凌靖
康伟斌
Original Assignee
宁德时代新能源科技股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 宁德时代新能源科技股份有限公司 filed Critical 宁德时代新能源科技股份有限公司
Priority to PCT/CN2022/094485 priority Critical patent/WO2023225796A1/zh
Priority to CN202280038504.5A priority patent/CN117441241A/zh
Publication of WO2023225796A1 publication Critical patent/WO2023225796A1/zh

Links

Images

Classifications

    • 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
    • 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

Definitions

  • the present application relates to the field of battery technology, and in particular to a positive active material, a preparation method thereof, a positive electrode sheet, a secondary battery, a battery module, a battery pack and an electrical device.
  • lithium-ion secondary batteries are widely used in energy storage power systems such as hydraulic, thermal, wind and solar power stations, and are used in power tools, electric bicycles, electric motorcycles, and electric vehicles. It is widely used in many fields such as military equipment, aerospace and so on. As lithium-ion secondary batteries have achieved great development, higher requirements have been placed on their energy density, cycle performance and safety performance.
  • lithium manganese phosphate As the cathode active material of lithium-ion secondary batteries, lithium manganese phosphate has the advantages of high capacity, good safety and low cost. However, lithium manganese phosphate has poor rate performance, which restricts its commercial application.
  • the present application provides a positive active material, a preparation method thereof, a positive electrode sheet, a secondary battery, a battery module, a battery pack and an electrical device to solve the problem of poor rate performance of lithium manganese phosphate positive active materials.
  • a first aspect of the application provides a cathode active material, including a core and a shell covering the core.
  • the core has a chemical formula Li a A x Mn 1-y B y P 1-z C z O 4-n D n , where A includes one or more elements selected from the group consisting of Zn, Al, Na, K, Mg, Nb, Mo and W, and B includes one or more elements selected from the group consisting of Ti, V, Zr, Fe, Ni, Mg, One or more elements from the group consisting of Co, Ga, Sn, Sb, Nb and Ge, C includes one or more elements selected from the group consisting of B (boron), S, Si and N, D Including one or more elements selected from the group consisting of S, F, Cl and Br, a is selected from the range of 0.9 to 1.1, x is selected from the range of 0.001 to 0.1, y is selected from the range of 0.001 to 0.5, z Selected from the range of 0.001 to 0.1
  • This application can obtain significantly improved rate performance by simultaneously doping specific elements in specific amounts at the Li site, Mn site, P site and O site of the compound LiMnPO 4 , while significantly reducing the dissolution of Mn and Mn site doping elements. , significantly improved cycle performance and/or high temperature stability are obtained, and the gram capacity and compacted density of the material can also be improved. At the same time, introducing doping element atoms into the shell will change the charge distribution around the carbon atoms and improve the conductivity of the shell.
  • the doping element atoms will create a defect structure inside the carbon material, which is conducive to the rapid migration of lithium ions; in addition, in the carbon New functional groups containing doping elements are generated on the surface, forming new active sites, increasing the speed of lithium ion solvation and desolvation, thereby improving capacity and rate performance.
  • the coating amount of the doped carbon layer is greater than 0% by weight and less than or equal to 6% by weight, optionally 3% by weight to 5% by weight. It not only gives full play to the conductive effect of the doped carbon layer, but also avoids the defect of too long lithium ion transmission path caused by excessive coating amount.
  • the mass content of the doping elements in the doped carbon layer is less than 30%; optionally, the mass content of the doping elements in the doped carbon layer is less than 20%.
  • Doping elements within the above content range can not only fully improve the conductivity of the pure carbon layer, but also effectively avoid excessive surface activity caused by excessive doping of doping elements, thus effectively controlling the effects of excessive doping of the cladding layer. interface side reactions.
  • the doping element is nitrogen, phosphorus, sulfur, boron or fluorine, and the doping element is selected from a single type of element to facilitate performance control of the doped carbon layer.
  • the doping element is nitrogen or sulfur
  • the mass content of the doping element in the doped carbon layer is 1% to 15%. Since nitrogen atoms and sulfur atoms interact with carbon The atomic atomic radii are closer and less likely to damage the carbon skeleton. Therefore, when the doping amount is within the above relatively broad range, the conductivity of the doped carbon layer can be fully exerted, and the lithium ion transport and lithium ion desolvation can be promoted. ability.
  • the doping element is phosphorus, boron or fluorine
  • the mass content of the doping element in the doped carbon layer is 0.5% to 5%. Since phosphorus atoms, boron The atomic radii of atoms and fluorine atoms are different from those of carbon atoms. Excessive doping can easily destroy the carbon skeleton. Therefore, when the doping amount is within the above relatively small range, the conductivity of the doped carbon layer can be fully exerted. It can also promote lithium ion transport and lithium ion desolvation capabilities.
  • A, C and D are each independently any element within the above respective ranges, and B is at least two elements within its range; optionally, A is selected from Mg and Nb, and/or B is at least two elements selected from the group consisting of Fe, Ti, V, Co and Mg, optionally Fe and Nb selected from the group consisting of Ti, V, Co and More than one element in the group consisting of Mg, and/or, C is S, and/or, D is F.
  • x is selected from the range of 0.001 to 0.005; and/or, y is selected from the range of 0.01 to 0.5, optionally selected from the range of 0.25 to 0.5; and/or, z is selected from the range The range of 0.001 to 0.005; and/or, n is selected from the range of 0.001 to 0.005.
  • (1-y):y is in the range of 1 to 4, optionally in the range of 1.5 to 3, and a:x is in the range of 9 to 1100, optionally in the range 190 -998 range.
  • the core has a lattice change rate of 8% or less, optionally 4% or less. As a result, the rate performance of the battery core can be improved.
  • the positive electrode active material has a Li/Mn antisite defect concentration of 2% or less, optionally 0.5% or less. As a result, the gram capacity and rate performance of the positive electrode active material can be improved.
  • the surface oxygen valence state of the cathode active material is -1.82 or less, optionally -1.89 to -1.98. As a result, the cycle performance and high-temperature stability of the battery core can be improved.
  • the positive active material has a compacted density at 3T of 2.0 g/cm or more, optionally 2.2 g/cm or more. As a result, the volumetric energy density of the battery core can be increased.
  • a second aspect of the present application provides a method for preparing any of the cathode active materials of the above-mentioned first aspect, the preparation method comprising the following steps:
  • step (1) Dissolve the manganese source, the source of element B and the acid in the solvent and stir to generate a suspension of manganese salt doped with element B. Filter the suspension and dry the filter cake to obtain element B doped.
  • the source of the above-mentioned element A is selected from at least one of the group consisting of elemental substance, oxide, phosphate, oxalate, carbonate and sulfate of element A
  • the source of element B is The source is selected from at least one of the group consisting of elements, oxides, phosphates, oxalates, carbonates and sulfates of element B
  • the source of element C is selected from the group consisting of sulfates, borate and nitric acid of element C.
  • the source of element D is selected from at least one of the group consisting of elemental elements and ammonium salts of element D
  • the carbon source is selected from starch, sucrose, glucose, cellulose, poly One or more of the group consisting of vinyl alcohol, polyethylene glycol, sodium carboxymethyl cellulose, citric acid, lactic acid, and succinic acid.
  • the source of the carbon layer doping element is selected from the source of nitrogen element and the source of phosphorus element.
  • the source of nitrogen element is selected from the group consisting of ethylenediamine, melamine, benzylamine, acetonitrile, ammoniated sucrose, pyrrole, Any one or more of the group consisting of aniline, acrylonitrile, polyimide acid, and nitrogen-containing aliphatic heterocyclic compounds;
  • the source of phosphorus element is selected from elemental phosphorus, diphosphorus pentoxide, ammonium dihydrogen phosphate, and ammonium phosphate , phosphoric acid, hypophosphorous acid, phosphorous acid, metaphosphoric acid, pyrophosphoric acid, polyphosphoric acid, phytic acid, phosphorus trichloride, phosphorus pentachloride, phosphorus tribromide, triphenoxyphosphorus, triphenylphosphine, tributyl Any one or more of the group consisting of phosphine;
  • the source of sulfur element is selected from sulfur powder, sulfuric acid, sulfurous acid, ammonium s
  • the source of fluorine element is selected from any one or more of the group consisting of hydrofluoric acid, ammonium fluoride, and fluorine-containing organic matter
  • the fluorine-containing organic matter is selected from fluorine-containing alkanes and fluorine-containing olefins. , any one of fluorine-containing aromatic hydrocarbons and fluorine-containing carboxylic acids.
  • the above-mentioned fluorine-containing organic substance may be further selected from any one or more of the group consisting of difluoromethane, difluoroethane, polytrifluoroethylene, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, etc.
  • the stirring in step (1) is performed at a temperature ranging from 60 to 120°C.
  • the stirring in step (1) is performed at a stirring rate of 200 to 800 rpm.
  • step (2) is performed for 8 to 15 hours.
  • the doping elements can be evenly distributed, and the crystallinity of the material after sintering is higher, thereby improving the gram capacity and rate performance of the material.
  • the sintering in step (4) is performed in a temperature range of 600 to 900°C for 6 to 14 hours. As a result, the high-temperature stability and cycle performance of the secondary battery can be improved.
  • a third aspect of the present application provides a positive electrode sheet, which includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode film layer includes any one of the positive electrode active materials of the above first aspect or is formed by
  • the cathode active material prepared by any one of the preparation methods of the second aspect and based on the total weight of the cathode film layer, the content of the cathode active material in the cathode film layer is more than 10% by weight, optionally, 95% by weight to 99.5% by weight.
  • a fourth aspect of the present application provides a secondary battery, which includes any one of the positive electrode active materials of the above-mentioned first aspect or a positive electrode active material prepared by any one of the preparation methods of the above-mentioned second aspect or the third aspect.
  • Positive pole piece is any one of the positive electrode active materials of the above-mentioned first aspect or a positive electrode active material prepared by any one of the preparation methods of the above-mentioned second aspect or the third aspect.
  • a fifth aspect of the present application provides a battery module including a secondary battery, wherein the secondary battery is the secondary battery of the fourth aspect.
  • a sixth aspect of the present application provides a battery pack, including a battery module, wherein the battery module is the battery module of the fifth aspect.
  • a seventh aspect of the present application provides an electrical device, including a secondary battery or a battery module or a battery pack, wherein the secondary battery is selected from the secondary battery of the fourth aspect, and the battery module is the battery module of the fifth aspect or The battery pack is a battery pack in the sixth aspect.
  • the characteristics of the cathode active material of the present application enable the secondary batteries, battery modules, and battery packs having the same to have higher cycle performance and rate characteristics, and further provide power-consuming devices having the secondary batteries, battery modules, or battery packs of the present application. Provides high power cycle stability and rate characteristics.
  • FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 1 .
  • FIG. 3 is a schematic diagram of a battery module according to an embodiment of the present application.
  • Figure 4 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 5 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 4 .
  • FIG. 6 is a schematic diagram of a power consumption device using a secondary battery as a power source according to an embodiment of the present application.
  • Ranges disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5.
  • the numerical range “a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range “0-5" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • step (c) means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c). , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b), etc.
  • condition "A or B” is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; Or both A and B are true (or exist).
  • Secondary batteries also known as rechargeable batteries or storage batteries, refer to batteries that can be recharged to activate active materials and continue to be used after the battery is discharged.
  • a secondary battery normally includes a positive electrode plate, a negative electrode plate, a separator and an electrolyte.
  • active ions such as lithium ions
  • the isolation film is placed between the positive electrode piece and the negative electrode piece. It mainly prevents the positive and negative electrodes from short-circuiting and allows active ions to pass through.
  • the electrolyte is between the positive electrode piece and the negative electrode piece and mainly plays the role of conducting active ions.
  • One embodiment of the present application provides a cathode active material, including a core and a shell covering the core.
  • the core has a chemical formula Li a A x Mn 1-y By P 1-z C z O 4-n D n , where , A includes one or more elements selected from the group consisting of Zn, Al, Na, K, Mg, Nb, Mo and W, B includes selected from the group consisting of Ti, V, Zr, Fe, Ni, Mg, Co, One or more elements from the group consisting of Ga, Sn, Sb, Nb and Ge, C includes one or more elements selected from the group consisting of B (boron), S, Si and N, D includes selected one or more elements from the group consisting of S, F, Cl and Br,
  • a is selected from the range of 0.9 to 1.1, such as 0.97, 0.977, 0.984, 0.988, 0.99, 0.991, 0.992, 0.993, 0.994, 0.995, 0.996, 0.997, 0.998, 1.01
  • x is selected from the range of 0.001 to 0.1, such as 0.001, 0.005,
  • y is selected from the range of 0.001 to 0.5, for example, 0.001, 0.005, 0.02, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.34, 0.345, 0.349, 0.35, 0.4
  • z is selected from the range of 0.001 to 0.1
  • the range for example, is 0.001, 0.005, 0.08, 0.1, n is selected from the range of 0.001 to 0.1, for example, 0.001, 0.005, 0.08, 0.1, and the cathode active material is electrically neutral;
  • the shell layer is a doped carbon layer, and the The doping elements
  • the above-mentioned limitation on the numerical range of x is not only a limitation on the stoichiometric number of each element as A, but also on the Limitation of the sum of stoichiometric numbers.
  • A is two or more elements A1, A2...An
  • the respective stoichiometric numbers x1, x2...xn of A1, A2...An must fall within the numerical range of x defined in this application, and x1
  • the sum of , x2...xn also needs to fall within this numerical range.
  • B, C and D are two or more elements
  • the limitations on the numerical ranges of the stoichiometric numbers of B, C and D in this application also have the above meaning.
  • the cathode active material of the present application is obtained by element doping in the compound LiMnPO 4 , where A, B, C and D are elements doped at the Li site, Mn site, P site and O site of the compound LiMnPO 4 respectively.
  • the performance improvement of lithium manganese phosphate is related to reducing the lattice change rate of lithium manganese phosphate and reducing surface activity during the process of deintercalating lithium. Reducing the lattice change rate can reduce the lattice constant difference between the two phases at the grain boundary, reduce the interface stress, and enhance the transport capability of Li + at the interface, thereby improving the rate performance of the cathode active material.
  • the lattice change rate is reduced by Li and Mn site doping.
  • Mn site doping also effectively reduces surface activity, thereby inhibiting Mn dissolution and interface side reactions between the cathode active material and the electrolyte.
  • P-site doping makes the Mn-O bond length change faster and reduces the material's small polaron migration barrier, thereby benefiting the electronic conductivity.
  • O-site doping has a good effect on reducing interface side reactions.
  • the doping of P-site and O-site also affects the Mn dissolution and kinetic properties of anti-site defects. Therefore, doping reduces the concentration of anti-site defects in the material, improves the dynamic properties and gram capacity of the material, and can also change the morphology of the particles, thereby increasing the compaction density.
  • this application can obtain significantly improved rate performance by simultaneously doping specific elements in specific amounts at the Li site, Mn site, P site and O site of the compound LiMnPO 4 , while significantly reducing the doping of Mn and Mn sites.
  • By dissolving the elements significantly improved cycle performance and/or high temperature stability are obtained, and the gram capacity and compacted density of the material can also be increased.
  • introducing doping element atoms into the shell will change the charge distribution around the carbon atoms and improve the conductivity of the shell.
  • the doping element atoms will create a defect structure inside the carbon material, which is conducive to the rapid migration of lithium ions; in addition, in the carbon New functional groups containing doping elements are generated on the surface, forming new active sites, increasing the speed of lithium ion solvation and desolvation, thereby improving capacity and rate performance.
  • the coating amount of the doped carbon layer is greater than 0% and less than or equal to 6% by weight, optionally 3% to 5% by weight. Controlling the coating amount of the doped carbon layer within the above range not only fully exerts the conductive effect of the doped carbon layer, but also avoids the defect of too long lithium ion transmission path caused by excessive coating amount.
  • the doped carbon layer has the advantage of better conductivity than the pure carbon layer, the greater the content of doping elements in the doped carbon layer, the stronger the activity of the shell layer.
  • the mass content of the doping elements is less than 30%; optionally, in the doped carbon layer, the mass content of the doping elements is less than 20%. Doping elements within the above content range can not only fully improve the conductivity of the pure carbon layer, but also effectively avoid excessive surface activity caused by excessive doping of doping elements, thus effectively controlling the effects of excessive doping of the cladding layer. interface side reactions.
  • the doping elements in the shell layer of the cathode active material of the present application can be a single element type or a combination of multiple elements. Since different elements have different conductive capabilities and abilities to form surface defects, in order to facilitate the doping of the doped carbon layer The performance can be adjusted more accurately.
  • the doping element is nitrogen, phosphorus, sulfur, boron or fluorine, and the doping element is selected from a single type of element to facilitate the doping of the carbon layer. performance control.
  • the doping element is nitrogen or sulfur
  • the mass content of the doping element in the doped carbon layer is 1% to 15%. Since nitrogen atoms and sulfur atoms interact with carbon The atomic atomic radii are closer and less likely to damage the carbon skeleton. Therefore, when the doping amount is within the above relatively broad range, the conductivity of the doped carbon layer can be fully exerted, and the lithium ion transport and lithium ion desolvation can be promoted. ability.
  • the doping element is phosphorus, boron or fluorine
  • the mass content of the doping element in the doped carbon layer is 0.5% to 5%. Since phosphorus atoms, boron The atomic radii of atoms and fluorine atoms are different from those of carbon atoms. Excessive doping can easily destroy the carbon skeleton. Therefore, when the doping amount is within the above relatively small range, the conductivity of the doped carbon layer can be fully exerted. It can also promote lithium ion transport and lithium ion desolvation capabilities.
  • A, C and D of the cathode active material are each independently any one element within the above respective ranges, and the B is at least two elements.
  • A is any element selected from Mg and Nb.
  • B is at least two elements selected from the group consisting of Fe, Ti, V, Co and Mg, optionally Fe and more than one element selected from the group consisting of Ti, V, Co and Mg,
  • C is S.
  • D is F.
  • x is selected from the range of 0.001 to 0.005 (such as 0.001, 0.002, 0.003, 0.004 or 0.005); and/or y is selected from the range of 0.01 to 0.5 (such as 0.01, 0.05 , 0.1, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45 or 0.5), optionally selected from the range of 0.25 to 0.5; and/or, z is selected from the range of 0.001 to 0.005 (such as 0.001, 0.002, 0.003, 0.004 or 0.005); and/or, n is selected from the range of 0.001 to 0.005 (such as 0.001, 0.002, 0.003, 0.004 or 0.005).
  • the gram capacity and rate performance of the material can be further improved.
  • the x value within the above range the dynamic properties of the material can be further improved.
  • the z value within the above range the rate performance of the secondary battery can be further improved.
  • the n value within the above range the high-temperature performance of the secondary battery can be further improved.
  • the cathode active material satisfies: (1-y): y is in the range of 1 to 4, optionally in the range of 1.5 to 3, and a:x is in the range of 9 to 1100, Optionally in the range 190-998.
  • y represents the sum of stoichiometric numbers of Mn-site doping elements.
  • the core has a lattice change rate of less than 8%, optionally, a lattice change rate of less than 4%.
  • a lattice change rate of less than 8%, optionally, a lattice change rate of less than 4%.
  • the positive electrode active material has a Li/Mn anti-site defect concentration of 2% or less, and optionally, the Li/Mn anti-site defect concentration is 0.5% or less.
  • the so-called Li/Mn antisite defect refers to the interchange of positions between Li + and Mn 2+ in the LiMnPO 4 lattice.
  • the Li/Mn anti-site defect concentration refers to the percentage of Li + exchanged with Mn 2+ in the positive active material to the total amount of Li + . Mn 2+ with anti-site defects will hinder the transport of Li + .
  • the Li/Mn anti-site defect concentration can be measured by methods known in the art, such as XRD.
  • the surface oxygen valence state of the cathode active material is -1.82 or less, optionally -1.89 to -1.98.
  • the interface side reaction between the positive electrode active material and the electrolyte can be reduced, thereby improving the cycle performance and high temperature stability of the secondary battery.
  • Surface oxygen valence state can be measured by methods known in the art, such as by electron energy loss spectroscopy (EELS).
  • the positive active material has a compacted density at 3 T (tons) of 2.0 g/cm or more, optionally 2.2 g/cm or more.
  • the compacted density can be measured according to GB/T 24533-2009.
  • the preparation method of the cathode active material of the present application is described below, but the following description is only an exemplary description, and those skilled in the art can use other feasible methods to prepare the cathode active material of the present application.
  • the preparation method of the cathode active material includes: Step (1): Dissolve a manganese source, a source of element B and an acid in a solvent and stir to generate a suspension of a manganese salt doped with element B, and The suspension is filtered and the filter cake is dried to obtain a manganese salt doped with element B; step (2): combine the lithium source, the phosphorus source, the source of element A, the source of element C, the source of element D, the carbon source, The source and solvent of the carbon layer doping element and the manganese salt doped with element B obtained in step (1) are added to the reaction vessel, ground and mixed to obtain a slurry; step (3): use the slurry obtained in step (2) The material is transferred to a spray drying equipment for spray drying and granulation to obtain particles; step (4): sintering the particles obtained in step (3) to obtain the above-mentioned positive electrode active material.
  • the added amounts of the respective sources of elements A, B, C, and D depend on the target doping amount
  • the acid in the above step (1) is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, organic acids such as oxalic acid, etc., for example, it can be oxalic acid.
  • the acid is a dilute acid with a concentration of 60% by weight or less.
  • the manganese source in the above step (1) can be a manganese-containing substance known in the art that can be used to prepare lithium manganese phosphate.
  • the manganese source can be selected from elemental manganese, manganese dioxide, manganese phosphate, One of manganese oxalate, manganese carbonate or their combination.
  • the lithium source in the above step (2) can be a lithium-containing substance known in the art that can be used to prepare lithium manganese phosphate.
  • the lithium source can be selected from the group consisting of lithium carbonate, lithium hydroxide, lithium phosphate, One of lithium dihydrogen phosphate or their combination.
  • the phosphorus source in the above step (2) can be a phosphorus-containing material known in the art that can be used to prepare lithium manganese phosphate.
  • the phosphorus source can be selected from diammonium hydrogen phosphate, ammonium dihydrogen phosphate, One or a combination of ammonium phosphate and phosphoric acid.
  • the source of the above-mentioned element A is selected from at least one of the group consisting of elemental elements, oxides, phosphates, oxalates, carbonates and sulfates of element A
  • the source of element B is selected from the group consisting of element B.
  • the source of element C is selected from the group consisting of sulfates, borate, nitrates and silicate of element C
  • the source of element D is selected from at least one of the group consisting of element D and ammonium salt
  • the carbon source is selected from starch, sucrose, glucose, cellulose, polyvinyl alcohol, polyethylene glycol
  • the source of the carbon layer doping element is selected from a source of nitrogen element, a source of phosphorus element, and a source of sulfur element. , one or more sources of boron element, and source of fluorine element.
  • the source of nitrogen element is selected from the group consisting of ethylenediamine, melamine, benzylamine, acetonitrile, ammoniated sucrose, pyrrole, aniline, acrylonitrile, poly Any one or more of the group consisting of imide acid and nitrogen-containing aliphatic heterocyclic compounds;
  • the source of phosphorus element is selected from elemental phosphorus, phosphorus pentoxide, ammonium dihydrogen phosphate, ammonium phosphate, phosphoric acid, hypophosphorous acid, In the group consisting of phosphorous acid, metaphosphoric acid, pyrophosphoric acid, polyphosphoric acid, phytic acid, phosphorus trichloride, phosphorus pentachloride, phosphorus tribromide, trip
  • the above-mentioned fluorine-containing organic substance may be further selected from any one or more of the group consisting of difluoromethane, difluoroethane, polytrifluoroethylene, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, etc.
  • the solvents in step (1) and step (2) can each independently be a solvent commonly used by those skilled in the art in the preparation of manganese salts and lithium manganese phosphates, for example, they can each independently be selected from At least one of ethanol, water (such as deionized water), etc.
  • the stirring in step (1) is performed at a temperature ranging from 60 to 120°C. In some embodiments, the stirring in step (1) is performed at a stirring rate of 200 to 800 rpm, or 300 to 800 rpm, or 400 to 800 rpm. In some embodiments, the stirring in step (1) is performed for 6 to 12 hours. In some embodiments, the grinding and mixing of step (2) is performed for 8 to 15 hours.
  • the doping elements can be evenly distributed and the crystallinity of the material after sintering is higher, thereby improving the gram capacity and rate performance of the material.
  • the filter cake may be washed before drying the filter cake in step (1).
  • the drying in step (1) can be performed by methods and conditions known to those skilled in the art.
  • the drying temperature can be in the range of 120 to 300°C.
  • the filter cake can be ground into particles after drying, for example, until the median diameter Dv50 of the particles is in the range of 50 to 200 nm.
  • the median particle diameter Dv50 refers to the particle diameter corresponding to when the cumulative volume distribution percentage of the positive active material reaches 50%.
  • the median particle size Dv50 of the cathode active material can be measured using laser diffraction particle size analysis. For example, refer to the standard GB/T 19077-2016 and use a laser particle size analyzer (such as Malvern Master Size 3000) for measurement.
  • the amount of carbon source relative to the amount of lithium source in step (2) is generally in the range of a molar ratio of 0.1% to 5%.
  • the grinding in step (2) can be performed by suitable grinding methods known in the art, for example, by sand grinding.
  • the temperature and time of spray drying in step (3) can be conventional temperatures and times used in spray drying in the art, for example, at 100 to 300°C for 1 to 6 hours.
  • sintering is performed at a temperature in the range of 600 to 900°C for 6 to 14 hours.
  • the crystallinity of the material can be controlled, and the dissolution of Mn and Mn-site doping elements after cycling of the positive electrode active material can be reduced, thereby improving the high-temperature stability and cycle performance of the battery.
  • sintering is performed under a protective atmosphere, which may be nitrogen, an inert gas, a mixture thereof, or a mixture of a protective atmosphere and hydrogen.
  • a protective atmosphere which may be nitrogen, an inert gas, a mixture thereof, or a mixture of a protective atmosphere and hydrogen.
  • a third aspect of the present application provides a positive electrode sheet, which includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode film layer includes any one of the positive electrode active materials of the above first aspect or is formed by
  • the cathode active material prepared by any one of the preparation methods of the second aspect and based on the total weight of the cathode film layer, the content of the cathode active material in the cathode film layer is more than 10% by weight, optionally, 95% by weight to 99.5% by weight.
  • the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • the metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the cathode active material may also be a cathode active material known in the art for batteries.
  • the cathode active material may further include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials of batteries can also be used. Only one type of these positive electrode active materials may be used alone, or two or more types may be used in combination.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (can also be abbreviated to NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (can also be abbreviated to NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (can also be abbreviated to NCM 622 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as Li Li
  • the olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), lithium manganese phosphate and carbon. At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • composites of lithium iron phosphate and carbon such as LiMnPO 4
  • LiMnPO 4 lithium manganese phosphate and carbon.
  • At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.
  • the positive electrode film layer optionally further includes a binder.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene tripolymer. At least one of a meta-copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer and a fluorine-containing acrylate resin.
  • the positive electrode film layer optionally further includes a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components in a solvent (such as N -methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode piece can be obtained.
  • a solvent such as N -methylpyrrolidone
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, where the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two surfaces opposite in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material.
  • the composite current collector can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative active material may be a negative active material known in the art for batteries.
  • the negative active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and the like.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon carbon composites, silicon nitrogen composites and silicon alloys.
  • the tin-based material may be selected from at least one of elemental tin, tin oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as battery negative electrode active materials can also be used. Only one type of these negative electrode active materials may be used alone, or two or more types may be used in combination.
  • the negative electrode film layer optionally further includes a binder.
  • the binder may be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), At least one of polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer optionally further includes a conductive agent.
  • the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode film layer optionally includes other auxiliaries, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative active materials, conductive agents, binders and any other components in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode piece can be obtained.
  • a solvent such as deionized water
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the type of electrolyte in this application can be selected according to needs.
  • the electrolyte can be liquid, gel, or completely solid.
  • the electrolyte is liquid and includes an electrolyte salt and a solvent.
  • the electrolyte salt may be selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonimide, lithium bistrifluoromethanesulfonimide, trifluoromethane At least one of lithium sulfonate, lithium difluorophosphate, lithium difluoroborate, lithium dioxaloborate, lithium difluorodioxalate phosphate and lithium tetrafluoroxalate phosphate.
  • the solvent may be selected from the group consisting of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, Butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate At least one of ester, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte optionally also includes additives.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.
  • the secondary battery further includes a separator film.
  • a separator film There is no particular restriction on the type of isolation membrane in this application. Any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be used.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.
  • the positive electrode piece, the negative electrode piece and the separator film can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an outer packaging.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • FIG. 1 shows a square-structured secondary battery 5 as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity.
  • the housing 51 has an opening communicating with the accommodation cavity, and the cover plate 53 can cover the opening to close the accommodation cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the containing cavity.
  • the electrolyte soaks into the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • secondary batteries can be assembled into battery modules, and the number of secondary batteries contained in the battery module can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery module.
  • FIG. 3 is a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having an accommodation space in which a plurality of secondary batteries 5 are accommodated.
  • the above-mentioned battery modules can also be assembled into a battery pack.
  • the number of battery modules contained in the battery pack can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box 2 and a lower box 3 .
  • the upper box 2 can be covered with the lower box 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided by the present application.
  • the secondary battery, battery module, or battery pack may be used as a power source for the electrical device, or may be used as an energy storage unit for the electrical device.
  • the electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, and electric golf carts). , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.
  • a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.
  • FIG. 6 is an electrical device as an example.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc.
  • a battery pack or battery module can be used.
  • Preparation of doped manganese oxalate add 1.3 mol of MnSO 4 . H 2 O, 0.7mol FeSO 4 . The H 2 O was mixed thoroughly in the mixer for 6 hours. The mixture was transferred to the reaction kettle, and 10 L of deionized water and 2 mol of oxalic acid dihydrate (calculated as oxalic acid) were added. The reaction kettle was heated to 80° C. and stirred at a rotation speed of 600 rpm for 6 hours. The reaction was terminated (no bubbles were generated), and an Fe-doped manganese oxalate suspension was obtained. The suspension is then filtered, and the filter cake is dried at 120° C. and then ground to obtain Fe-doped manganese oxalate particles with a median particle size Dv 50 of about 100 nm.
  • Preparation of doped lithium manganese phosphate Take 1 mol of the above manganese oxalate particles, 0.497 mol of lithium carbonate, 0.001 mol of Mo(SO 4 ) 3 , an 85% phosphoric acid aqueous solution containing 0.999 mol of phosphoric acid, and 0.001 mol of H 4 SiO 4 , 0.0005mol NH 4 HF 2 , 0.05mol sucrose and 0.025mol ethylenediamine were added to 20L deionized water. The mixture was transferred to a sand mill and thoroughly ground and stirred for 10 hours to obtain a slurry. Transfer the slurry to spray drying equipment for spray drying and granulation.
  • the above-mentioned positive electrode active material, polyvinylidene fluoride (PVDF), and acetylene black were added to N-methylpyrrolidone (NMP) in a weight ratio of 90:5:5, and stirred in a drying room to form a slurry.
  • NMP N-methylpyrrolidone
  • the above slurry is coated on aluminum foil, dried and cold pressed to form a positive electrode sheet.
  • the coating amount is 0.2g/cm 2 and the compacted density is 2.0g/cm 3 .
  • Lithium sheet is used as the negative electrode, and 1 mol/L LiPF 6 is used in ethylene carbonate with a volume ratio of 1:1:1.
  • Polyethylene (PE) porous polymer film is used as the isolation film, and the positive electrode piece, isolation film, and negative electrode piece are stacked in order so that the isolation film is between the positive and negative electrodes for isolation, and the bare battery core is obtained by winding .
  • Preparation of manganese oxalate add 1 mol of MnSO 4 . H 2 O was added to the reaction kettle, and 10 L of deionized water and 1 mol of oxalic acid dihydrate (calculated as oxalic acid) were added. The reaction kettle was heated to 80°C and stirred at 600 rpm for 6 hours. The reaction was terminated (no bubbles were generated), and a manganese oxalate suspension was obtained. The suspension is then filtered, and the filter cake is dried at 120° C. and then ground to obtain manganese oxalate particles with a median particle size Dv 50 of 50-200 nm.
  • Preparation of lithium manganese phosphate Take 1 mol of the above manganese oxalate particles, 0.5 mol of lithium carbonate, an 85% phosphoric acid aqueous solution containing 1 mol of phosphoric acid, 0.05 mol of sucrose and 0.025 mol of ethylenediamine and add them to 20 L of deionized water. The mixture was transferred to a sand mill and thoroughly ground and stirred for 10 hours to obtain a slurry. Transfer the slurry to spray drying equipment for spray drying and granulation. Set the drying temperature to 250°C and dry for 4 hours to obtain granules. In a protective atmosphere of nitrogen (90 volume %) + hydrogen (10 volume %), the above powder was sintered at 700° C. for 10 hours to obtain carbon-coated LiMnPO 4 .
  • Spherical aberration electron microscopy was used to characterize the internal microstructure and surface structure of the cathode active material with high spatial resolution, and the chemical formula of the cathode active material was obtained by combining three-dimensional reconstruction technology.
  • the content of the carbon coating was measured using an elemental analyzer.
  • the doping element content of the carbon coating layer was measured using inductively coupled plasma emission spectroscopy.
  • the positive active material sample is prepared into a buckle, and the buckle is charged at a small rate of 0.05C until the current is reduced to 0.01C. Then take out the positive electrode piece from the battery and soak it in DMC for 8 hours. Then it is dried, scraped into powder, and particles with a particle size less than 500nm are screened out. Take a sample and calculate its lattice constant v1 in the same way as the above-mentioned test of the fresh sample. (v0-v1)/v0 ⁇ 100% is shown in the table as the lattice change rate before and after complete deintercalation of lithium.
  • the drainage method is to first separately measure the gravity F 1 of the battery cell using a balance that automatically converts units based on the dial data, then completely places the battery core in deionized water (density is known to be 1g/cm 3 ), and measures the battery core at this time.
  • the battery of the embodiment always maintained an SOC of more than 99% during the experiment until the end of storage.
  • the positive electrode active material compositions of Examples 1-11 and Comparative Examples 1-8 are shown in Table 1.
  • Table 2 shows the performance data of the positive electrode active materials of Examples 1-11 and Comparative Examples 1-8 measured according to the above performance test method with or without electricity.
  • Table 3 shows the positive electrode active material compositions of Examples 12-61 and Comparative Examples 9 to 19.
  • Table 4 shows the performance data of the cathode active materials of Examples 12-61 and Comparative Examples 9 to 19, either with or without electricity, measured according to the above performance testing method.
  • the core doping of the cathode material is beneficial to improving the iron dissolution problem, and has a significant effect on improving the initial capacity, battery rate performance, and cycle performance of the material.

Abstract

本申请实施例提供一种正极活性材料、其制备方法、正极极片、二次电池、电池模块、电池包和用电装置。正极活性材料包括内核和包覆内核的壳层，内核具有化学式LiaAxMn1-yByP1-zCzO4-nDn，其中，A包括选自Zn、Al、Na、K、Mg、Nb、Mo和W中的一种或多种元素，B包括选自Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge中的一种或多种元素，C包括选自B、S、Si和N中的一种或多种元素，D包括选自S、F、Cl和Br中的一种或多种元素，壳层为掺杂碳层，掺杂碳层中的掺杂元素包括选自氮、磷、硫、硼、氟中的任意一种或多种。提高了磷酸锰锂系正极活性材料的倍率性能和循环性能。

Description

正极活性材料、其制备方法、正极极片、二次电池、电池模块、电池包和用电装置 技术领域
本申请涉及电池技术领域，特别是涉及一种正极活性材料、其制备方法、正极极片、二次电池、电池模块、电池包和用电装置。
背景技术
近年来，随着锂离子二次电池技术的发展，锂离子二次电池广泛应用于水力、火力、风力和太阳能电站等储能电源系统，并在电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域有着广泛应用。由于锂离子二次电池取得了极大的发展，因此对其能量密度、循环性能和安全性能等也提出了更高的要求。
磷酸锰锂作为锂离子二次电池的正极活性材料，具有容量高、安全性好、成本低的优点。然而磷酸锰锂的倍率性能较差，制约了其商业化应用。
发明内容
本申请提供了一种正极活性材料、其制备方法、正极极片、二次电池、电池模块、电池包和用电装置，以解决磷酸锰锂系正极活性材料的倍率性能差的问题。
本申请的第一方面，提供了一种正极活性材料，包括内核和包覆内核的壳层，内核具有化学式Li aA xMn 1-yB yP 1-zC zO 4-nD n，其中，A包括选自Zn、Al、Na、K、Mg、Nb、Mo和W组成的组中的一种或多种元素，B包括选自Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge组成的组中的一种或多种元素，C包括选自B(硼)、S、Si和N组成的组中的一种或多种元素，D包括选自S、F、Cl和Br组成的组中的一种或多种元素，a选自0.9至1.1的范围，x选自0.001至0.1的范围，y选自0.001至0.5的范围，z选自0.001至0.1的范围，n选自0.001至0.1的范围，并且正极活性材料为电中性的；壳层为掺杂碳层，掺杂碳层中的掺杂元素包括选自氮、磷、硫、硼、氟组成的组中的任意一种或多种。
本申请通过在化合物LiMnPO 4的Li位、Mn位、P位和O位同时以特定量掺杂特定的元素，能够获得明显改善的倍率性能，同时显著减少了Mn与Mn位掺杂元素的溶出，获得了显著改善的循环性能和/或高温稳定性，并且材料的克容量和压实密度也可以得到提高。同时在以壳层引入掺杂元素原子会改变碳原子周围的电荷分布，提高壳层的导电性，而且掺杂元素原子在碳材料内部造成缺陷结构，有利于锂离子的快速迁移；另外在碳表面产生新的含有掺杂元素的官能团，形成新的活性位点，提高锂离子溶剂化和去溶剂化的速度，从而提高容量和倍率性能。
在第一方面的任意实施方式中，基于内核的重量计，掺杂碳层的包覆量为大于0重量％且小于等于6重量％，可选为3重量％～5重量％。既充分发挥了掺杂碳层的导电作 用，又避免了包覆量过多造成的锂离子传输路径过长的缺陷。
在第一方面的任意实施方式中，掺杂碳层中，掺杂元素的质量含量在30％以下；可选地掺杂碳层中，掺杂元素的质量含量在20％以下。在上述含量范围内的掺杂元素，既可以充分改善纯碳层的导电性，又有效避免了因掺杂元素掺入过多导致表面活性过强，从而有效控制了包覆层掺杂过量导致的界面副反应。
在第一方面的任意实施方式中，可选地，掺杂元素为氮、磷、硫、硼或氟，掺杂元素选择单一种类的元素，便于对掺杂碳层的性能控制。
在第一方面的任意实施方式中，可选地，掺杂元素为氮元素或硫元素，掺杂碳层中掺杂元素的质量含量为1％～15％，由于氮原子和硫原子与碳原子原子半径更相近，不易破坏碳骨架，因此，其掺杂量在上述相对宽泛的范围内时，既可以充分发挥掺杂碳层的导电性，又可以促进锂离子传输和锂离子去溶剂化能力。
在第一方面的任意实施方式中，可选地，掺杂元素为磷元素、硼元素或氟元素，掺杂碳层中掺杂元素的质量含量为0.5％～5％，由于磷原子、硼原子和氟原子与碳原子的原子半径有差别，过多掺杂易破坏碳骨架，因此，其掺杂量在上述相对较小的范围内时，既可以充分发挥掺杂碳层的导电性，又可以促进锂离子传输和锂离子去溶剂化能力。
在第一方面的任意实施方式中，A、C和D各自独立地为上述各自范围内的任一种元素，并且B为其范围内的至少两种元素；可选地，A为选自Mg和Nb中的任一种元素，和/或，B为选自Fe、Ti、V、Co和Mg组成的组中的至少两种元素，可选地为Fe与选自Ti、V、Co和Mg组成的组中的一种以上元素，和/或，C为S，和/或，D为F。由此，能够进一步改善二次电池的倍率性能、克容量和/或高温性能。
在第一方面的任意实施方式中，x选自0.001至0.005的范围；和/或，y选自0.01至0.5的范围，可选地选自0.25至0.5的范围；和/或，z选自0.001至0.005的范围；和/或，n选自0.001至0.005的范围。由此，能够进一步提升材料的克容量和倍率性能和/或动力学性能，和/或进一步提升电池的倍率性能和/或电池的高温性能。
在第一方面的任意实施方式中，(1-y):y在1至4范围内，可选地在1.5至3范围内，且a:x在9到1100范围内，可选地在190-998范围内。由此，正极活性材料的能量密度和循环性能可进一步提升。
在第一方面的任意实施方式中，内核的晶格变化率为8％以下，可选地为4％以下。由此，能够改善电芯的倍率性能。
在第一方面的任意实施方式中，正极活性材料的Li/Mn反位缺陷浓度为2％以下，可选地为0.5％以下。由此，能够提高正极活性材料的克容量和倍率性能。
在第一方面的任意实施方式中，正极活性材料的表面氧价态为-1.82以下，可选地为-1.89～-1.98。由此，能够改善电芯的循环性能和高温稳定性。
在第一方面的任意实施方式中，正极活性材料在3T下的压实密度为2.0g/cm 3以上，可选地为2.2g/cm 3以上。由此，能够提高电芯的体积能量密度。
本申请的第二方面提供了一种上述第一方面的任意一种正极活性材料的制备方法，该制备方法包括以下步骤：
(1)将锰源、元素B的源和酸在溶剂中溶解并搅拌，生成掺杂元素B的锰盐的悬浊液，将悬浊液过滤并烘干滤饼，得到掺杂了元素B的锰盐；(2)将锂源、磷源、元素A的源、元素C的源、元素D的源、碳源、碳层掺杂元素的源、溶剂和由步骤(1)获得的掺杂了元素B的锰盐加入反应容器中研磨并混合，得到浆料；(3)将由步骤(2)获得的浆料转移到喷雾干燥设备中进行喷雾干燥造粒，得到颗粒；(4)将由步骤(3)获得的颗粒进行烧结，得到正极活性材料。
在第二方面的任意实施方式中，上述元素A的源选自元素A的单质、氧化物、磷酸盐、草酸盐、碳酸盐和硫酸盐组成的组中的至少一种，元素B的源选自元素B的单质、氧化物、磷酸盐、草酸盐、碳酸盐和硫酸盐组成的组中的至少一种，元素C的源选自元素C的硫酸盐、硼酸盐、硝酸盐和硅酸盐组成的组中的至少一种，元素D的源选自元素D的单质和铵盐组成的组中的至少一种，碳源选自淀粉、蔗糖、葡萄糖、纤维素、聚乙烯醇、聚乙二醇、羧甲基纤维素钠、柠檬酸、乳酸、琥珀酸组成的组中的一种或多种，碳层掺杂元素的源选自氮元素的源、磷元素的源、硫元素的源、硼元素的源、氟元素的源组成的组中的一种或多种，氮元素的源选自乙二胺、三聚氰胺、苄胺、乙腈、氨化蔗糖、吡咯、苯胺、丙烯腈、聚酰亚胺酸、含氮脂杂环化合物组成的组中的任意一种或多种；磷元素的源选自单质磷、五氧化二磷、磷酸二氢铵、磷酸铵、磷酸、次磷酸、亚磷酸、偏磷酸、焦磷酸、多聚磷酸、植酸、三氯化磷、五氯化磷、三溴化磷、三苯氧磷、三苯基膦、三丁基膦组成的组中的任意一种或多种；硫元素的源选自硫粉、硫酸、亚硫酸、硫酸铵、噻吩、噻唑、硫脲、二甲基亚砜、硫代乙酰胺、硫醇组成的组中的任意一种或多种；硼元素的源选自单质硼、硼酸、三氧化二硼、氮化硼、硼酸三甲酯、四苯基硼酸钠、三氯化硼组成的组中的任意一种或多种；氟元素的源选自氢氟酸、氟化铵、含氟有机物组成的组中的任意一种或多种，含氟有机物选自含氟烷烃、含氟烯烃、含氟芳烃、含氟羧酸中的任意一种。通过在上述范围内选择各掺杂元素的源，能够改善材料的性能。
上述含氟有机物可以进一步地选自二氟甲烷、二氟乙烷、聚三氟乙烯、聚四氟乙烯、聚偏氟乙烯、聚氟乙烯等组成的组中的任意一种或多种。
在第二方面的任意实施方式中，步骤(1)的搅拌在60～120℃范围内的温度下进行。
在第二方面的任意实施方式中，步骤(1)的搅拌通过在200～800rpm的搅拌速率下进行。
在第二方面的任意实施方式中，步骤(2)的研磨并混合进行8～15小时。
由此，通过控制掺杂时的反应温度、搅拌速率和混合时间，能够使掺杂元素均匀分布，并且烧结后材料的结晶度更高，从而可提升材料的克容量和倍率性能等。
在第二方面的任意实施方式中，步骤(4)的烧结在600～900℃的温度范围内进行6～14小时。由此，能够改善二次电池的高温稳定性和循环性能。
本申请的第三方面提供了一种正极极片，其包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，正极膜层包括上述第一方面的任意一种正极活性材料或通过上述第二方面的任意一种制备方法制备的正极活性材料，并且基于正极膜层的总重量 计，正极活性材料在正极膜层中的含量为10重量％以上，可选地，95重量％至99.5重量％。
本申请的第四方面提供了一种二次电池，其中，包括上述第一方面的任意一种正极活性材料或通过上述第二方面的任意一种制备方法制备的正极活性材料或第三方面的正极极片。
本申请的第五方面提供了一种电池模块，包括二次电池，其中，二次电池为第四方面的二次电池。
本申请的第六方面提供了一种电池包，包括电池模块，其中电池模块为第五方面的电池模块。
本申请的第七方面提供了一种用电装置，包括二次电池或电池模块或电池包，其中，二次电池选自第四方面的二次电池、电池模块为第五方面的电池模块或电池包为第六方面的电池包。
本申请的正极活性材料的特点，使得具有其的二次电池、电池模块、电池包具有较高的循环性能、倍率特性，进而为具有本申请二次电池、电池模块或电池包的用电装置提供了较高的动力循环稳定性和倍率特性。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需要使用的附图作简单地介绍，显而易见地，下面所描述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，在不付出创造性劳动的前提下，还可以根据附图获得其他的附图。
图1是本申请一实施方式的二次电池的示意图。
图2是图1所示的本申请一实施方式的二次电池的分解图。
图3是本申请一实施方式的电池模块的示意图。
图4是本申请一实施方式的电池包的示意图。
图5是图4所示的本申请一实施方式的电池包的分解图。
图6是本申请一实施方式的二次电池用作电源的用电装置的示意图。
在附图中，附图并未按照实际的比例绘制。
附图标记说明：
1电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳体；52电极组件；53顶盖组件。
具体实施方式
下面结合附图和实施例对本申请的实施方式作进一步详细描述。以下实施例的详细描述和附图用于示例性地说明本申请的原理，但不能用来限制本申请的范围，即本申请不限于所描述的实施例。
以下，适当地参照附图详细说明具体公开了本申请的正极活性材料及其制备方法、正极极片、负极极片、二次电池、电池模块、电池包和用电装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
[二次电池]
二次电池又称为充电电池或蓄电池，是指在电池放电后可通过充电的方式使活性材料激活而继续使用的电池。
通常情况下，二次电池包括正极极片、负极极片、隔离膜及电解液。在电池充放电过程中，活性离子(例如锂离子)在正极极片和负极极片之间往返嵌入和脱出。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使活性离子通过。电解液在正极极片和负极极片之间，主要起到传导活性离子的作用。
[正极活性材料]
本申请的一个实施方式提供一种正极活性材料，包括内核和包覆内核的壳层，内核具有化学式Li aA xMn 1-yB yP 1-zC zO 4-nD n，其中，A包括选自Zn、Al、Na、K、Mg、Nb、Mo和W组成的组中的一种或多种元素，B包括选自Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge组成的组中的一种或多种元素，C包括选自B(硼)、S、Si和N组成的组中的一种或多种元素，D包括选自S、F、Cl和Br组成的组中的一种或多种元素，
a选自0.9至1.1的范围，例如为0.97、0.977、0.984、0.988、0.99、0.991、0.992、0.993、0.994、0.995、0.996、0.997、0.998、1.01，x选自0.001至0.1的范围，例如为0.001、0.005，y选自0.001至0.5的范围，例如为0.001、0.005、0.02、0.05、0.1、0.15、0.2、0.25、0.3、0.34、0.345、0.349、0.35、0.4，z选自0.001至0.1的范围，例如为0.001、0.005、0.08、0.1，n选自0.001至0.1的范围，例如为0.001、0.005、0.08、0.1，并且正极活性材料为电中性的；壳层为掺杂碳层，掺杂碳层中的掺杂元素包括选自氮、磷、硫、硼、氟组成的组中的任意一种或多种。
除非另有说明，否则上述化学式中，当A为两种以上元素时，上述对于x数值范围的限定不仅是对每种作为A的元素的化学计量数的限定，也是对各个作为A的元素的化学计量数之和的限定。例如当A为两种以上元素A1、A2……An时，A1、A2……An各自的化学计量数x1、x2……xn各自均需落入本申请对x限定的数值范围内，且x1、x2……xn之和也需落入该数值范围内。类似地，对于B、C和D为两种以上元素的情况，本申请中对B、C和D化学计量数的数值范围的限定也具有上述含义。
本申请的正极活性材料通过在化合物LiMnPO 4中进行元素掺杂而获得，其中，A、B、C和D分别为在化合物LiMnPO 4的Li位、Mn位、P位和O位掺杂的元素。不希望囿于理论，现认为磷酸锰锂的性能提升与减小脱嵌锂过程中磷酸锰锂的晶格变化率和降低表面活性有关。减小晶格变化率可减小晶界处两相间的晶格常数差异，减小界面应力，增强Li +在界面处的传输能力，从而提升正极活性材料的倍率性能。而表面活性高容易导致界面副反应严重，加剧产气、电解液消耗和破坏界面，从而影响电池的循环等性能。本申请中，通过Li和Mn位掺杂减小了晶格变化率。Mn位掺杂还有效降低表面活性，从而抑制Mn溶出和正极活性材料与电解液的界面副反应。P位掺杂使Mn-O键长的变化速率更快，降低材料的小极化子迁移势垒，从而有利于电子电导率。O位掺杂对减小界面副反应有良好的作用。P位和O位的掺杂还对反位缺陷的Mn溶出及动力学性能产生影响。因此，掺杂减小了材料中反位缺陷浓度，提高材料的动力学性能和克容量，还可以改变颗粒的形貌，从而提升压实密度。
由此，本申请通过在化合物LiMnPO 4的Li位、Mn位、P位和O位同时以特定量掺杂特定的元素，能够获得明显改善的倍率性能，同时显著减少了Mn与Mn位掺杂元素的溶出，获得了显著改善的循环性能和/或高温稳定性，并且材料的克容量和压实密度也可以得到提高。同时在以壳层引入掺杂元素原子会改变碳原子周围的电荷分布，提高壳层的导电性，而且掺杂元素原子在碳材料内部造成缺陷结构，有利于锂离子的快速迁移；另外在碳表面产生新的含有掺杂元素的官能团，形成新的活性位点，提高锂离子溶剂化和去溶剂化的速度，从而提高容量和倍率性能。
在第一方面的一些实施方式中，基于内核的重量计，掺杂碳层的包覆量为大于0重量％且小于等于6重量％，可选为3重量％～5重量％。将掺杂碳层的包覆量控制在上述范围内，既充分发挥了掺杂碳层的导电作用，又避免了包覆量过多造成的锂离子传输路径过长的缺陷。
掺杂碳层虽然相对于纯碳层具有导电性更好的优势，但是当掺杂碳层中掺杂元素的含量越多，壳层的活性越强，在第一方面的一些实施方式中，掺杂碳层中，掺杂元素的质量含量在30％以下；可选地掺杂碳层中，掺杂元素的质量含量在20％以下。在上述含量范围内的掺杂元素，既可以充分改善纯碳层的导电性，又有效避免了因掺杂元素掺入过多导致表面活性过强，从而有效控制了包覆层掺杂过量导致的界面副反应。
本申请的正极活性材料的壳层中的掺杂元素可以为单一元素种类也可以为多种元素的组合，由于不同元素的导电能力、形成表面缺陷的能力不同，为了便于对掺杂碳层的性能进行更精确的调节，在第一方面的任意实施方式中，可选地，掺杂元素为氮、磷、硫、硼或氟，掺杂元素选择单一种类的元素，便于对掺杂碳层的性能控制。
另外，由于不同种类的掺杂元素的导电能力、形成表面缺陷的能力不同，为了实现掺杂元素作用的充分发挥，对不同种类的掺杂元素的含量进行试验。
在第一方面的任意实施方式中，可选地，掺杂元素为氮元素或硫元素，掺杂碳层中掺杂元素的质量含量为1％～15％，由于氮原子和硫原子与碳原子原子半径更相近，不易破坏碳骨架，因此，其掺杂量在上述相对宽泛的范围内时，既可以充分发挥掺杂碳层的导电性，又可以促进锂离子传输和锂离子去溶剂化能力。
在第一方面的任意实施方式中，可选地，掺杂元素为磷元素、硼元素或氟元素，掺杂碳层中掺杂元素的质量含量为0.5％～5％，由于磷原子、硼原子和氟原子与碳原子的原子半径有差别，过多掺杂易破坏碳骨架，因此，其掺杂量在上述相对较小的范围内时，既可以充分发挥掺杂碳层的导电性，又可以促进锂离子传输和锂离子去溶剂化能力。
在第一方面的一些实施方式中，正极活性材料的A、C和D各自独立地为上述各自范围内的任一种元素，并且所述B为至少两种元素。由此，能够更容易且准确地控制正极活性材料的组成。
可选地，A为选自Mg和Nb中的任一种元素，通过在上述范围内对Li位掺杂元素进行选择，能够进一步减小脱锂过程中的晶格变化率，从而进一步改善电池的倍率性能。
可选地，B为选自Fe、Ti、V、Co和Mg组成的组的至少两种元素，可选地为Fe 与选自Ti、V、Co和Mg组成的组的一种以上元素，通过在上述范围内对Mn位掺杂元素进行选择，能够进一步提高电子电导率并进一步减小晶格变化率，从而提升电池的倍率性能和克容量。
可选地，C为S，通过在上述范围内对P位掺杂元素进行选择，能够进一步改善电池的倍率性能。
可选地，D为F。通过在上述范围内对O位掺杂元素进行选择，能够进一步减轻界面的副反应，提升电池的高温性能。
在第一方面的一些实施方式中，x选自0.001至0.005的范围(比如为0.001、0.002、0.003、0.004或0.005)；和/或，y选自0.01至0.5的范围(比如为0.01、0.05、0.1、0.2、0.25、0.3、0.35、0.4、0.45或0.5)，可选地选自0.25至0.5的范围；和/或，z选自0.001至0.005的范围(比如为0.001、0.002、0.003、0.004或0.005)；和/或，n选自0.001至0.005的范围(比如为0.001、0.002、0.003、0.004或0.005)。通过在上述范围内对y值进行选择，能够进一步提升材料的克容量和倍率性能。通过在上述范围内对x值进行选择，能够进一步提升材料的动力学性能。通过在上述范围内对z值进行选择，能够进一步提升二次电池的倍率性能。通过在上述范围内对n值进行选择，能够进一步提升二次电池的高温性能。
在第一方面的一些实施方式中，正极活性材料满足：(1-y):y在1至4范围内，可选地在1.5至3范围内，且a:x在9到1100范围内，可选地在190-998范围内。此处y表示Mn位掺杂元素的化学计量数之和。在满足上述条件时，正极活性材料的能量密度和循环性能可进一步提升。
在第一方面的一些实施方式中，内核的晶格变化率为8％以下，可选地，晶格变化率为4％以下。通过降低晶格变化率，能够使得Li离子传输更容易，即Li离子在材料中的迁移能力更强，有利于改善二次电池的倍率性能。晶格变化率可通过本领域中已知的方法，例如X射线衍射图谱(XRD)测得。
在第一方面的一些实施方式中，正极活性材料的Li/Mn反位缺陷浓度为2％以下，可选地，Li/Mn反位缺陷浓度为0.5％以下。所谓Li/Mn反位缺陷，指的是LiMnPO 4晶格中，Li +与Mn 2+的位置发生互换。Li/Mn反位缺陷浓度指的是正极活性材料中与Mn 2+发生互换的Li +占Li +总量的百分比。反位缺陷的Mn 2+会阻碍Li +的传输，通过降低Li/Mn反位缺陷浓度，有利于提高正极活性材料的克容量和倍率性能。Li/Mn反位缺陷浓度可通过本领域中已知的方法，例如XRD测得。
在第一方面的一些实施方式中，正极活性材料的表面氧价态为-1.82以下，可选地为-1.89～-1.98。通过降低表面氧价态，能够减轻正极活性材料与电解液的界面副反应，从而改善二次电池的循环性能和高温稳定性。表面氧价态可通过本领域中已知的方法测量，例如通过电子能量损失谱(EELS)测量。
在第一方面的一些实施方式中，正极活性材料在3T(吨)下的压实密度为2.0g/cm 3以上，可选地为2.2g/cm 3以上。压实密度越高，单位体积活性材料的重量越大，因此提高压实密度有利于提高电芯的体积能量密度。压实密度可依据GB/T 24533-2009测 量。
以下对本申请的正极活性材料的准备方法进行说明，但是以下说明仅为示例性说明，本领域技术人员可以采用其他能够实现的方法来制备本申请的正极活性材料。
在一些实施方式中，正极活性材料的制备方法包括：步骤(1)：将锰源、元素B的源和酸在溶剂中溶解并搅拌，生成掺杂元素B的锰盐的悬浊液，将悬浊液过滤并烘干滤饼，得到掺杂了元素B的锰盐；步骤(2)：将锂源、磷源、元素A的源、元素C的源、元素D的源、碳源、碳层掺杂元素的源、溶剂和由步骤(1)获得的掺杂了元素B的锰盐加入反应容器中研磨并混合，得到浆料；步骤(3)：将由步骤(2)获得的浆料转移到喷雾干燥设备中进行喷雾干燥造粒，得到颗粒；步骤(4)：将由步骤(3)获得的颗粒进行烧结，得到上述正极活性材料。元素A、B、C、D各自的源的加入量取决于目标掺杂量，锂源、锰源和磷源的用量之比符合化学计量比。
在一些实施方式中，上述步骤(1)的酸选自盐酸、硫酸、硝酸、磷酸、有机酸如草酸等中的一种或多种，例如可为草酸。在一些实施方式中，上述酸为浓度为60重量％以下的稀酸。
在一些实施方式中，上述步骤(1)的锰源可为本领域已知的可用于制备磷酸锰锂的含锰物质，例如所述锰源可选自单质锰、二氧化锰、磷酸锰、草酸锰、碳酸锰中的一种或它们的组合。
在一些实施方式中，上述步骤(2)的锂源可为本领域已知的可用于制备磷酸锰锂的含锂物质，例如所述锂源可选自碳酸锂、氢氧化锂、磷酸锂、磷酸二氢锂中的一种或它们的组合。
在一些实施方式中，上述步骤(2)的磷源可为本领域已知的可用于制备磷酸锰锂的含磷物质，例如所述磷源可选自磷酸氢二铵、磷酸二氢铵、磷酸铵和磷酸中的一种或它们的组合。
可选地，上述元素A的源选自元素A的单质、氧化物、磷酸盐、草酸盐、碳酸盐和硫酸盐组成的组中的至少一种，元素B的源选自元素B的单质、氧化物、磷酸盐、草酸盐、碳酸盐和硫酸盐组成的组中的至少一种，元素C的源选自元素C的硫酸盐、硼酸盐、硝酸盐和硅酸盐组成的组中的至少一种，元素D的源选自元素D的单质和铵盐组成的组中的至少一种，碳源选自淀粉、蔗糖、葡萄糖、纤维素、聚乙烯醇、聚乙二醇、羧甲基纤维素钠、柠檬酸、乳酸、琥珀酸组成的组中的一种或多种，碳层掺杂元素的源选自氮元素的源、磷元素的源、硫元素的源、硼元素的源、氟元素的源组成的组中的一种或多种，氮元素的源选自乙二胺、三聚氰胺、苄胺、乙腈、氨化蔗糖、吡咯、苯胺、丙烯腈、聚酰亚胺酸、含氮脂杂环化合物组成的组中的任意一种或多种；磷元素的源选自单质磷、五氧化二磷、磷酸二氢铵、磷酸铵、磷酸、次磷酸、亚磷酸、偏磷酸、焦磷酸、多聚磷酸、植酸、三氯化磷、五氯化磷、三溴化磷、三苯氧磷、三苯基膦、三丁基膦组成的组中的任意一种或多种；硫元素的源选自硫粉、硫酸、亚硫酸、硫酸铵、噻吩、噻唑、硫脲、二甲基亚砜、硫代乙酰胺、硫醇组成的组中的任意一种或多种；硼元素的源选自单质硼、硼酸、三氧化二硼、氮化硼、硼酸三甲酯、四苯基硼酸钠、三氯化硼组成的组中的任意一种或多种；氟元素的源选自氢氟酸、氟化铵、含氟有机物组成的 组中的任意一种或多种，含氟有机物选自含氟烷烃、含氟烯烃、含氟芳烃、含氟羧酸中的任意一种。通过选择各掺杂元素的源，能够提高掺杂元素分布的均匀性，从而改善材料的性能。
上述含氟有机物可以进一步地选自二氟甲烷、二氟乙烷、聚三氟乙烯、聚四氟乙烯、聚偏氟乙烯、聚氟乙烯等组成的组中的任意一种或多种。
在一些实施方式中，步骤(1)和步骤(2)中的溶剂各自独立地可为本领域技术人员在锰盐和磷酸锰锂的制备中常规使用的溶剂，例如其可各自独立地选自乙醇、水(例如去离子水)中的至少一种等。
在一些实施方式中，步骤(1)的搅拌在60～120℃范围内的温度下进行。在一些实施方式中，步骤(1)的搅拌通过在200～800rpm，或300～800rpm，或400～800rpm的搅拌速率下进行。在一些实施方式中，步骤(1)的搅拌进行6～12小时。在一些实施方式中，步骤(2)的研磨并混合进行8～15小时。
通过控制掺杂时的反应温度、搅拌速率和混合时间，能够使掺杂元素均匀分布，并且烧结后材料的结晶度更高，从而可提升材料的克容量和倍率性能等。
在一些实施方式中，在步骤(1)中烘干滤饼之前可对滤饼进行洗涤。
在一些实施方式中，步骤(1)中的烘干可通过本领域技术人员已知的方式和已知的条件进行，例如，烘干温度可在120～300℃范围内。可选地，可在烘干后将滤饼研磨成颗粒，例如研磨至颗粒的中值粒径Dv50在50～200nm范围内。其中，中值粒径Dv50是指，所述正极活性材料累计体积分布百分数达到50％时所对应的粒径。在本申请中，正极活性材料的中值粒径Dv50可采用激光衍射粒度分析法测定。例如参照标准GB/T 19077-2016，使用激光粒度分析仪(例如Malvern Master Size 3000)进行测定。
在一些实施方式中，在步骤(2)中碳源的用量相对于锂源的用量通常在摩尔比0.1％-5％的范围内。步骤(2)的研磨可通过本领域已知的适合的研磨方式进行，例如可通过砂磨进行。
步骤(3)的喷雾干燥的温度和时间可为本领域中进行喷雾干燥时常规的温度和时间，例如，在100～300℃下，进行1～6小时。
在一些实施方式中，烧结在600～900℃的温度范围内进行6-14小时。通过控制烧结温度和时间，能够控制材料的结晶度，降低正极活性材料的循环后Mn与Mn位掺杂元素的溶出量，从而改善电池的高温稳定性和循环性能。
在一些实施方式中，烧结在保护气氛下进行，保护气氛可为氮气、惰性气体或其混合物、或者保护气氛与氢气的混合物。
[正极极片]
本申请的第三方面提供了一种正极极片，其包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，正极膜层包括上述第一方面的任意一种正极活性材料或通过上述第二方面的任意一种制备方法制备的正极活性材料，并且基于正极膜层的总重量计，正极活性材料在正极膜层中的含量为10重量％以上，可选地，95重量％至99.5重量％。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，正极活性材料还可采用本领域公知的用于电池的正极活性材料。作为示例，正极活性材料还可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM 333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM 523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM 211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM 622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM 811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。
在一些实施方式中，正极膜层还可选地包括粘结剂。作为示例，粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。
在一些实施方式中，正极膜层还可选地包括导电剂。作为示例，导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
[负极极片]
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极膜层，所述负极膜层包括负极活性材料。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极膜层设置 在负极集流体相对的两个表面中的任意一者或两者上。
在一些实施方式中，负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施方式中，负极膜层还可选地包括粘结剂。作为示例，粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。
在一些实施方式中，负极膜层还可选地包括导电剂。作为示例，导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，负极膜层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极极片。
[电解质]
电解质在正极极片和负极极片之间起到传导离子的作用。本申请对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。
在一些实施方式中，电解质为液态的，且包括电解质盐和溶剂。
在一些实施方式中，电解质盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟二草酸磷酸锂及四氟草酸磷酸锂中的至少一种。
在一些实施方式中，溶剂可选自碳酸亚乙酯、碳酸亚丙酯、碳酸甲乙酯、碳酸 二乙酯、碳酸二甲酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、氟代碳酸亚乙酯、甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、1,4-丁内酯、环丁砜、二甲砜、甲乙砜及二乙砜中的至少一种。
在一些实施方式中，电解液还可选地包括添加剂。作为示例，添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
[隔离膜]
在一些实施方式中，二次电池中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，二次电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图1是作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图2，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，二次电池可以组装成电池模块，电池模块所含二次电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图3是作为一个示例的电池模块4。参照图3，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个二次电池5容纳于 该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。
图4和图5是作为一个示例的电池包1。参照图4和图5，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
另外，本申请还提供一种用电装置，所述用电装置包括本申请提供的二次电池、电池模块、或电池包中的至少一种。所述二次电池、电池模块、或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。
作为所述用电装置，可以根据其使用需求来选择二次电池、电池模块或电池包。
图6是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
[实施例]
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
实施例1
1)正极活性材料的制备
制备掺杂的草酸锰：将1.3mol的MnSO 4﹒H 2O、0.7mol的FeSO 4﹒H 2O在混料机中充分混合6小时。将混合物转移至反应釜中，并加入10L去离子水和2mol二水合草酸(以草酸计)。将反应釜加热至80℃，以600rpm的转速搅拌6小时，反应终止(无气泡产生)，得到Fe掺杂的草酸锰悬浮液。然后过滤所述悬浮液，将滤饼在120℃下烘干，之后进行研磨，得到中值粒径Dv 50为100nm左右的Fe掺杂的草酸锰颗粒。
制备掺杂的磷酸锰锂：取1mol上述草酸锰颗粒、0.497mol碳酸锂、0.001mol的Mo(SO 4) 3、含有0.999mol磷酸的浓度为85％的磷酸水溶液、0.001mol的H 4SiO 4、0.0005mol的NH 4HF 2和0.05mol蔗糖和0.025mol乙二胺加入到20L去离子水中。将混合物转入砂磨机中充分研磨搅拌10小时，得到浆料。将所述浆料转移到喷雾干燥设备中进行喷雾干燥造粒，设定干燥温度为250℃，干燥4小时，得到颗粒。在氮气(90体积％) +氢气(10体积％)保护气氛中，将上述粉料在700℃下烧结10小时，得到掺杂碳层包覆的Li 0.994Mo 0.001Mn 0.65Fe 0.35P 0.999Si 0.001O 3.999F 0.001。
2)扣式电池的制备
将上述正极活性材料、聚偏二氟乙烯(PVDF)、乙炔黑以90：5：5的重量比加入至N-甲基吡咯烷酮(NMP)中，在干燥房中搅拌制成浆料。在铝箔上涂覆上述浆料，干燥、冷压制成正极极片。涂覆量为0.2g/cm 2，压实密度为2.0g/cm 3。
采用锂片作为负极，采用1mol/L的LiPF 6在体积比1：1：1的碳酸乙烯酯
(EC)、碳酸二乙酯(DEC)和碳酸二甲酯(DMC)中的溶液为电解液，与上述制备的正极极片一起在扣电箱中组装成扣式电池(下文也称“扣电”)。
3)全电池的制备
将上述正极活性材料与导电剂乙炔黑、粘结剂聚偏二氟乙烯(PVDF)按重量比92：2.5：5.5在N-甲基吡咯烷酮溶剂体系中混合均匀后，涂覆于铝箔上并烘干、冷压，得到正极极片。涂覆量为0.4g/cm 2，压实密度为2.4g/cm 3。
将负极活性材料人造石墨、硬碳、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)按照重量比90：5：2：2：1在去离子水中混合均匀后，涂覆于铜箔上烘干、冷压，得到负极极片。涂覆量为0.2g/cm 2，压实密度为1.7g/cm 3。
以聚乙烯(PE)多孔聚合薄膜作为隔离膜，将正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正负极中间起到隔离的作用，并卷绕得到裸电芯。将裸电芯置于外包装中，注入与上述制备扣电时相同的电解液并封装，得到全电池(下文也称“全电”)。
实施例2
除了在“1)正极活性材料的制备”中，将高纯Li 2CO 3的量改变为0.4885mol，将Mo(SO 4) 3换成MgSO 4，将FeSO 4﹒H 2O的量改变为0.68mol，在制备掺杂的草酸锰时还加入0.02mol的Ti(SO 4) 2，并将H 4SiO 4换成HNO 3之外，其他与实施例1相同。
实施例3
除了在“1)正极活性材料的制备”中，将高纯Li 2CO 3的量改变为0.496mol，将Mo(SO 4) 3换成W(SO 4) 3，将H 4SiO 4换成H 2SO 4之外，其他与实施例1相同。
实施例4
除了在“1)正极活性材料的制备”中，将高纯Li 2CO 3的量改变为0.4985mol，将0.001mol的Mo(SO 4) 3换成0.0005mol的Al 2(SO 4) 3和NH 4HF 2换成NH 4HCl 2之外，其他与实施例1相同。
实施例5
除了在“1)正极活性材料的制备”中，将0.7mol的FeSO 4﹒H 2O改为0.69mol，在制备掺杂的草酸锰时还加入0.01molVCl 2，将Li 2CO 3的量改变为0.4965mol， 将0.001mol的Mo(SO 4) 3换成0.0005mol的Nb 2(SO 4) 5和H 4SiO 4换成H 2SO 4之外，其他与实施例1相同。
实施例6
除了在“1)正极活性材料的制备”中，将FeSO 4﹒H 2O的量改为0.68mol，在制备掺杂的草酸锰时还加入0.01mol的VCl 2和0.01mol的MgSO 4，将Li 2CO 3的量改变为0.4965mol，将0.001mol的Mo(SO 4) 3换成0.0005mol的Nb 2(SO 4) 5和H 4SiO 4换成H 2SO 4之外，其他与实施例1相同。
实施例7
除了在“1)正极活性材料的制备”中，将MgSO 4换成CoSO 4之外，其他与实施例6相同。
实施例8
除了在“1)正极活性材料的制备”中，将MgSO 4换成NiSO 4之外，其他与实施例6相同。
实施例9
除了在“1)正极活性材料的制备”中，将FeSO 4﹒H 2O的量改为0.698mol，在制备掺杂的草酸锰时还加入0.002mol的Ti(SO 4) 2，将Li 2CO 3的量改变为0.4955mol，将0.001mol的Mo(SO 4) 3换成0.0005mol的Nb 2(SO 4) 5，H 4SiO 4换成H 2SO 4，NH 4HF 2制成NH 4HCl 2之外，其他与实施例1相同。
实施例10
除了在“1)正极活性材料的制备”中，将FeSO 4﹒H 2O的量改为0.68mol，在制备掺杂的草酸锰时还加入0.01mol的VCl 2和0.01mol的MgSO 4，将Li 2CO 3的量改变为0.4975mol，将0.001mol的Mo(SO 4) 3换成0.0005mol的Nb 2(SO 4) 5和NH 4HF 2换成NH 4HBr 2之外，其他与实施例1相同。
实施例11
除了在“1)正极活性材料的制备”中，将FeSO 4﹒H 2O的量改为0.69mol，在制备掺杂的草酸锰时还加入0.01mol的VCl 2，将Li 2CO 3的量改变为0.499mol，将Mo(SO 4) 3换成MgSO 4和NH 4HF 2换成NH 4HBr 2之外，其他与实施例1相同。
实施例12
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.36mol，将FeSO 4﹒H 2O的量改为0.6mol，在制备掺杂的草酸锰时还加入0.04mol的VCl 2，将Li 2CO 3的量改变为0.4985mol，将Mo(SO 4) 3换成MgSO 4和H 4SiO 4换成HNO 3之外，其他与实施例1相同。
实施例13
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.16mol，FeSO 4﹒H 2O的量改为0.8mol之外，其他与实施例12相同。
实施例14
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.3mol，VCl 2的量改为0.1mol之外，其他与实施例12相同。
实施例15
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.2mol，在制备掺杂的草酸锰时还加入0.1mol的VCl 2，将Li 2CO 3的量改变为0.494mol，将0.001mol的Mo(SO 4) 3换成0.005mol的MgSO 4和H 4SiO 4换成H 2SO 4之外，其他与实施例1相同。
实施例16
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.2mol，在制备掺杂的草酸锰时还加入0.1mol的VCl 2，将Li 2CO 3的量改变为0.467mol，将0.001mol的Mo(SO 4) 3换成0.005mol的MgSO 4，0.001mol的H 4SiO 4换成0.005mol的H 2SO 4和1.175mol浓度为85％的磷酸换成1.171mol浓度为85％的磷酸之外，其他与实施例1相同。
实施例17
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.2mol，在制备掺杂的草酸锰时还加入0.1mol的VCl 2，将Li 2CO 3的量改变为0.492mol，将0.001mol的Mo(SO 4) 3换成0.005mol的MgSO 4，H 4SiO 4换成H 2SO 4和0.0005mol的NH 4HF 2改成0.0025mol之外，其他与实施例1相同。
实施例18
除了在“1)正极活性材料的制备”中，将FeSO 4﹒H 2O的量改为0.5mol，在制备掺杂的草酸锰时还加入0.1mol的VCl 2和0.1mol的CoSO 4，将Li 2CO 3的量改变为0.492mol，将0.001mol的Mo(SO 4) 3换成0.005mol的MgSO 4，H 4SiO 4换成H 2SO 4和0.0005mol的NH 4HF 2改成0.0025mol之外，其他与实施例1相同。
实施例19
除了在“1)正极活性材料的制备”中，将FeSO 4﹒H 2O的量改为0.4mol，将0.1mol的CoSO 4改为0.2mol之外，其他与实施例18相同。
实施例20
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.5mol，FeSO 4﹒H 2O的量改为0.1mol，CoSO 4的量改为0.3mol之外，其他与实施例18相同。
实施例21
除了在“1)正极活性材料的制备”中，将0.1mol的CoSO 4换成0.1mol的NiSO 4之外，其他与实施例18相同。
实施例22
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.5mol，FeSO 4﹒H 2O的量改为0.2mol，将0.1mol的CoSO 4换成0.2mol的NiSO 4之外，其他与实施例18相同。
实施例23
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.4mol，FeSO 4﹒H 2O的量改为0.3mol，CoSO 4的量改为0.2mol之外，其他与实施例18相同。
实施例24
除了在“1)正极活性材料的制备”中，将1.3mol的MnSO 4﹒H 2O改为1.2mol，0.7mol的FeSO 4﹒H 2O改为0.5mol，在制备掺杂的草酸锰时还加入0.1mol的VCl 2和0.2mol的CoSO 4，将Li 2CO 3的量改变为0.497mol，将0.001mol的Mo(SO 4) 3换成0.005mol的MgSO 4，H 4SiO 4换成H 2SO 4和0.0005mol的NH 4HF 2改成0.0025mol之外，其他与实施例1相同。
实施例25
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.0mol，FeSO 4﹒H 2O的量改为0.7mol，CoSO 4的量改为0.2mol之外，其他与实施例18相同。
实施例26
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.4mol，FeSO 4﹒H 2O的量改为0.3mol，在制备掺杂的草酸锰时还加入0.1mol的VCl 2和0.2mol的CoSO 4，将Li 2CO 3的量改变为0.4825mol，将0.001mol的Mo(SO 4) 3换成0.005mol的MgSO 4，H 4SiO 4的量改成0.1mol，磷酸的量改成0.9mol和NH 4HF 2的量改成0.04mol之外，其他与实施例1相同。
实施例27
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.4mol，FeSO 4﹒H 2O的量改为0.3mol，在制备掺杂的草酸锰时还加入0.1mol的VCl 2和0.2mol的CoSO 4，将Li 2CO 3的量改变为0.485mol，将0.001mol的Mo(SO 4) 3换成0.005mol的MgSO 4，H 4SiO 4的量改成0.08mol，磷酸的量改成0.92mol和NH 4HF 2的量改成0.05mol之外，其他与实施例1相同。
实施例28
除了在“1)正极活性材料的制备”中，将乙二胺的量改为0.0013mol，其他与实施例1相同。
实施例29
除了在“1)正极活性材料的制备”中，将乙二胺的量改为0.0026mol，其他与实施例1相同。
实施例30
除了在“1)正极活性材料的制备”中，将乙二胺的量改为0.0535mol，其他与实施例1相同。
实施例31
除了在“1)正极活性材料的制备”中，将乙二胺的量改为0.0818mol，其他与实施例1相同。
实施例32
除了在“1)正极活性材料的制备”中，将乙二胺的量改为0.12mol，其他与实施例1相同。
实施例33
除了在“1)正极活性材料的制备”中，将乙二胺的量改为0.2571mol，其他与实施例1相同。
实施例34
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0005mol磷酸(来源于质量分数为85％的磷酸，以下磷酸的来源均与之相同)，其他与实施例1相同。
实施例35
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0012mol磷酸，其他与实施例1相同。
实施例36
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0072mol磷酸，其他与实施例1相同。
实施例37
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0122mol磷酸，其他与实施例1相同。
实施例38
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0202mol磷酸，其他与实施例1相同。
实施例39
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0317mol磷酸，其他与实施例1相同。
实施例40
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0581mol磷酸，其他与实施例1相同。
实施例41
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0011mol硫酸(来源于质量分数为60％的硫酸，以下硫酸的来源均与之相同)，其他与实施例1相同。
实施例42
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0023mol硫酸，其他与实施例1相同。
实施例43
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0196mol硫酸，其他与实施例1相同。
实施例44
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0397mol硫酸，其他与实施例1相同。
实施例45
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0563mol硫酸，其他与实施例1相同。
实施例46
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.075mol硫酸，其他与实施例1相同。
实施例47
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.1212mol硫酸，其他与实施例1相同。
实施例48
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0013mol硼酸，其他与实施例1相同。
实施例49
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0033mol硼酸，其他与实施例1相同。
实施例50
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0202mol硼酸，其他与实施例1相同。
实施例51
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0344mol硼酸，其他与实施例1相同。
实施例52
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0569mol硼酸，其他与实施例1相同。
实施例53
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0893mol硼酸，其他与实施例1相同。
实施例54
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.1636mol硼酸，其他与实施例1相同
实施例55
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0008mol氟化氢(来源于质量分数为40％的氢氟酸，以下氟化氢的来源均与之相同)，其他与实施例1相同。
实施例56
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0019mol氟化氢，其他与实施例1相同。
实施例57
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0117mol氟化氢，其他与实施例1相同。
实施例58
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0199mol氟化氢，其他与实施例1相同。
实施例59
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.033mol氟化氢，其他与实施例1相同。
实施例60
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0517mol氟化氢，其他与实施例1相同。
实施例61
除了在“1)正极活性材料的制备”中，将0.025mol乙二胺改为0.0947mol氟化氢，其他与实施例1相同。
对比例1
制备草酸锰：将1mol的MnSO 4﹒H 2O加至反应釜中，并加入10L去离子水和1mol二水合草酸(以草酸计)。将反应釜加热至80℃，以600rpm的转速搅拌6小时,反应终止(无气泡产生)，得到草酸锰悬浮液。然后过滤所述悬浮液，将滤饼在120℃下烘干，之后进行研磨，得到中值粒径Dv 50为50-200nm的草酸锰颗粒。
制备磷酸锰锂：取1mol上述草酸锰颗粒、0.5mol碳酸锂、含有1mol磷酸的浓度为85％的磷酸水溶液和0.05mol蔗糖和0.025mol乙二胺加入到20L去离子水中。将混合物转入砂磨机中充分研磨搅拌10小时，得到浆料。将所述浆料转移到喷雾干燥设备中进行喷雾干燥造粒，设定干燥温度为250℃，干燥4小时，得到颗粒。在氮气(90体积％)+氢气(10体积％)保护气氛中，将上述粉料在700℃下烧结10小时，得到碳包覆的LiMnPO 4。
对比例2
除了在对比例1中，将1mol的MnSO 4﹒H 2O换成0.85mol的MnSO 4﹒H 2O和0.15mol的FeSO 4﹒H 2O，并加入到混料机中充分混合6小时之后再加入反应釜之外，其它与对比例1相同。
对比例3
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.9mol，0.7mol的FeSO 4﹒H 2O换成0.1mol的ZnSO 4，将Li 2CO 3的量改变为0.495mol，将0.001mol的Mo(SO 4) 3换成0.005mol的MgSO 4，将磷酸的量改成1mol，不加入H 4SiO 4和NH 4HF 2之外，其他与实施例1相同。
对比例4
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.2mol，FeSO 4﹒H 2O的量改为0.8mol，将Li 2CO 3的量改变为0.45mol，将0.001mol的Mo(SO 4) 3换成0.005mol的Nb 2(SO 4) 5，将0.999mol的磷酸改成1mol，0.0005mol的NH 4HF 2改成0.025mol，不加入H 4SiO 4之外，其他与实施例1相同。
对比例5
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.4mol，FeSO 4﹒H 2O的量改为0.6mol，将Li 2CO 3的量改变为0.38mol，将0.001mol的Mo(SO 4) 3换成0.12mol的MgSO 4之外，其他与实施例1相同。
对比例6
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为0.8mol，0.7mol的FeSO 4﹒H 2O换成1.2mol的ZnSO 4，将Li 2CO 3的量改变为0.499mol，将0.001mol的Mo(SO 4) 3换成0.001mol的MgSO 4之外，其他与实施例1相同。
对比例7
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.4mol，FeSO 4﹒H 2O的量改为0.6mol，将Li 2CO 3的量改变为0.534mol，将0.001mol的Mo(SO 4) 3换成0.001mol的MgSO 4，将磷酸的量改成0.88mol，H 4SiO 4的量改成0.12mol，NH 4HF 2的量改成0.025mol之外，其他与实施例1相同。
对比例8
除了在“1)正极活性材料的制备”中，将MnSO 4﹒H 2O的量改为1.2mol，FeSO 4﹒H 2O的量改为0.8mol，将Li 2CO 3的量改变为0.474mol，将0.001mol的Mo(SO 4) 3换成0.001mol的MgSO 4，将磷酸的量改成0.93mol，H 4SiO 4的量改成0.07mol，NH 4HF 2的量改成0.06mol之外，其他与实施例1相同。
对比例9
除了在“1)正极活性材料的制备”中，不添加乙二胺外其他与实施例1相同。
对比例10
除了在“1)正极活性材料的制备”中，不添加乙二胺外其他与实施例2相同。
对比例11
除了在“1)正极活性材料的制备”中，不添加乙二胺外其他与实施例3相同。
对比例12
除了在“1)正极活性材料的制备”中，不添加乙二胺外其他与实施例4相同。
对比例13
除了在“1)正极活性材料的制备”中，不添加乙二胺外其他与实施例5相同。
对比例14
除了在“1)正极活性材料的制备”中，不添加乙二胺外其他与实施例6相同。
对比例15
除了在“1)正极活性材料的制备”中，不添加乙二胺外其他与实施例7相同。
对比例16
除了在“1)正极活性材料的制备”中，不添加乙二胺外其他与实施例8相同。
对比例17
除了在“1)正极活性材料的制备”中，不添加乙二胺外其他与实施例9相同。
对比例18
除了在“1)正极活性材料的制备”中，不添加乙二胺外其他与实施例10相同。
对比例19
除了在“1)正极活性材料的制备”中，不添加乙二胺外其他与实施例11相同。
二、正极活性材料性质及电池性能测试方法
1.正极活性材料化学式的测定
采用球差电镜仪(ACSTEM)对正极活性材料内部微观结构和表面结构进行高空间分辨率表征，结合三维重构技术得到正极活性材料的化学式。利用元素分析仪对碳包覆层的含量进行测量。利用电感耦合等离子体发射光谱对碳包覆层的掺杂元素含量进行测量。
2.晶格变化率测量方法
在25℃恒温环境下，将正极活性材料样品置于XRD(型号为Bruker D8 Discover)中，采用1°/min对样品进行测试，并对测试数据进行整理分析，参照标准PDF卡片，计算出此时的晶格常数a0、b0、c0和v0(a0,b0和c0表示晶胞各个方面上的长度大小，v0表示晶胞体积，可通过XRD精修结果直接获取)。
采用上述实施例中扣电制备方法，将所述正极活性材料样品制备成扣电，并对上述扣电以0.05C小倍率进行充电，直至电流减小至0.01C。然后将扣电中的正极极片取出，并置于DMC中浸泡8小时。然后烘干，刮粉，并筛选出其中粒径小于500nm的颗粒。取样并按照与上述测试新鲜样品同样的方式计算出其晶格常数v1，将(v0-v1)/v0×100％作为其完全脱嵌锂前后的晶格变化率示于表中。
3.Li/Mn反位缺陷浓度测量方法
将“晶格变化率测量方法”中测试的XRD结果与标准晶体的PDF(Powder Diffraction File)卡片对比，得出Li/Mn反位缺陷浓度。具体而言，将“晶格变化率测量方法”中测试的XRD结果导入通用结构分析系统(GSAS)软件中，自动获得精修结果，其中包含了不同原子的占位情况，通过读取精修结果获得Li/Mn反位缺陷浓度。
4.表面氧价态测量方法
取5g正极活性材料样品按照上述实施例中所述扣电制备方法制备成扣电。对扣电采用0.05C小倍率进行充电，直至电流减小至0.01C。然后将扣电中的正极极片取出，并置于DMC中浸泡8小时。然后烘干，刮粉，并筛选出其中粒径小于500nm的颗粒。将所得颗粒用电子能量损失谱(EELS，所用仪器型号为Talos F200S)进行测量，获取能量损失近边结构(ELNES)，其反映元素的态密度和能级分布情况。根据态密度和能级分布，通过对价带态密度数据进行积分，算出占据的电子数，从而推算出充电后的表面氧的价态。
5.压实密度测量方法
取5g的粉末放于压实专用模具(美国CARVER模具，型号13mm)中,然后将模具放在压实密度仪器上。施加3T的压力，在设备上读出压力下粉末的厚度(卸压后的厚度)，通过ρ＝m/v，计算出压实密度。
6.循环后Mn(以及Mn位掺杂的Fe)溶出量测量方法
将45℃下循环至容量衰减至80％后的全电池采用0.1C倍率进行放电至截止电压2.0V。然后将电池拆开，取出负极极片，在负极极片上随机取30个单位面积(1540.25mm 2)的圆片，用Agilent ICP-OES730测试电感耦合等离子体发射光谱(ICP)。根据ICP结果计算其中Fe(如果正极活性材料的Mn位掺杂有Fe的话)和Mn的量，从而计算循环后Mn(以及Mn位掺杂的Fe)的溶出量。测试标准依据EPA-6010D-2014。
7.扣式电池初始克容量测量方法
在2.5～4.3V下，将扣式电池按照0.1C充电至4.3V，然后在4.3V下恒压充电至电流小于等于0.05mA，静置5min，然后按照0.1C放电至2.0V，此时的放电容量为初始克容量，记为D0。
8.3C充电恒流比测量方法
在25℃恒温环境下，将新鲜全电池静置5min，按照1/3C放电至2.5V。静置5min，按照1/3C充电至4.3V，然后在4.3V下恒压充电至电流小于等于0.05mA。静置5min，记录此时的充电容量为C0。按照1/3C放电至2.5V，静置5min，再按照3C充电至4.3V，静置5min，记录此时的充电容量为C1。3C充电恒流比即为C1/C0×100％。
3C充电恒流比越高，说明电池的倍率性能越好。
9.全电池45℃循环性能测试
在45℃的恒温环境下，在2.5～4.3V下，将全电池按照1C充电至4.3V，然后在4.3V下恒压充电至电流小于等于0.05mA。静置5min，然后按照1C放电至2.5V，记录此时的放电容量为D0。重复前述充放电循环，直至放电容量降低到D0的80％。记录此时电池经过的循环圈数。
10.全电池60℃胀气测试
在60℃下，存储100％充电状态(SOC)的全电池。在存储前后及过程中测量电芯的开路电压(OCV)和交流内阻(IMP)以监控SOC，并测量电芯的体积。其中在每存储48h后取出全电池，静置1h后测试开路电压(OCV)、内阻(IMP)，并在冷却至室温后用排水法测量电芯体积。排水法即先用表盘数据自动进行单位转换的天平单独测量电芯的重力F 1，然后将电芯完全置于去离子水(密度已知为1g/cm 3)中，测量此时的电芯的重力F 2，电芯受到的浮力F 浮即为F 1-F 2，然后根据阿基米德原理F 浮＝ρ×g×V 排，计算得到电芯体积V＝(F 1-F 2)/(ρ×g)。
由OCV、IMP测试结果来看，本实验过程中直至存储结束，实施例的电池始终保持99％以上的SOC。
存储30天后，测量电芯体积，并计算相对于存储前的电芯体积，存储后的电芯体积增加的百分比。
另外，测量电芯残余容量。在2.5～4.3V下，将全电池按照1C充电至4.3V，然后在4.3V下恒压充电至电流小于等于0.05mA。静置5min，记录此时的充电容量为电芯残余容量。
表1中示出实施例1-11和对比例1-8的正极活性材料组成。表2中示出实施例1-11和对比例1-8的正极活性材料或扣电或全电按照上述性能测试方法测得的性能数据。表3示出实施例12-61、对比例9至19的正极活性材料组成。表4中示出实施例12-61、对比例9至19的正极活性材料或扣电或全电按照上述性能测试方法测得的性能数据。
表1实施例1-11和对比例1-8的正极活性材料组成
Figure PCTCN2022094485-appb-000001
表2实施例1-11和对比例1-8的正极活性材料或扣电或全电按照上述性能测试方法测得的性能数据
Figure PCTCN2022094485-appb-000002
Figure PCTCN2022094485-appb-000003
根据表2中的数据可以看出，正极材料的内核掺杂有利于改善铁溶出问题，并且对提高材料的初始容量、电池倍率性能、循环性能具有明显作用。
表3实施例12-61、对比例9至19的正极活性材料组成
Figure PCTCN2022094485-appb-000004
Figure PCTCN2022094485-appb-000005
Figure PCTCN2022094485-appb-000006
Figure PCTCN2022094485-appb-000007
表4实施例12至61、对比例9至19的正极活性材料或扣电或全电按照上述性能测试方法测得的性能数据
Figure PCTCN2022094485-appb-000008
Figure PCTCN2022094485-appb-000009
Figure PCTCN2022094485-appb-000010
由上述4可知，掺杂碳层相比未掺杂碳，正极材料的比容量和倍率性能也得到了相应的提升。
虽然已经参考优选实施例对本申请进行了描述，但在不脱离本申请的范围的情况下，可以对其进行各种改进并且可以用等效物替换其中的部件。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (18)

  1. 一种正极活性材料，包括内核和包覆所述内核的壳层，所述内核具有化学式Li aA xMn 1-yB yP 1-zC zO 4-nD n，
    其中，所述A包括选自Zn、Al、Na、K、Mg、Nb、Mo和W组成的组中的一种或多种元素，
    所述B包括选自Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge组成的组中的一种或多种元素，
    所述C包括选自B(硼)、S、Si和N组成的组中的一种或多种元素，
    所述D包括选自S、F、Cl和Br组成的组中的一种或多种元素，
    所述a选自0.9至1.1的范围，所述x选自0.001至0.1的范围，所述y选自0.001至0.5的范围，所述z选自0.001至0.1的范围，所述n选自0.001至0.1的范围，并且所述正极活性材料为电中性的；
    所述壳层为掺杂碳层，所述掺杂碳层中的掺杂元素包括选自氮、磷、硫、硼、氟组成的组中的任意一种或多种。
  2. 根据权利要求1所述的正极活性材料，其中，基于所述内核的重量计，所述掺杂碳层的包覆量为大于0重量％且小于等于6重量％，可选为3重量％～5重量％。
  3. 根据权利要求1或2所述的正极活性材料，其中，所述掺杂碳层中，所述掺杂元素的质量含量在30％以下；可选地所述掺杂碳层中，所述掺杂元素的质量含量在20％以下。
  4. 根据权利要求1至3中任一项所述的正极活性材料，其中，
    所述掺杂元素为氮元素和/或硫元素，所述掺杂碳层中掺杂元素的质量含量为1％～15％；或者
    所述掺杂元素为磷元素、硼元素和/或氟元素，所述掺杂碳层中掺杂元素的质量含量为0.5％～5％；
    可选地所述掺杂元素为氮、磷、硫、硼或氟。
  5. 根据权利要求1至4中任一项所述的正极活性材料，其中，所述A、C和D各自独立地为上述各自范围内的任一种元素，并且所述B为其范围内的至少两种元素；
    可选地，
    所述A为选自Mg和Nb中的任一种元素，和/或，
    所述B为选自Fe、Ti、V、Co和Mg组成的组中的至少两种元素，可选地为Fe与选自Ti、V、Co和Mg组成的组中的一种以上元素，和/或，
    所述C为S，和/或，
    所述D为F。
  6. 根据权利要求1至5中任一项所述的正极活性材料，其中，所述x选自0.001至0.005的范围；和/或，所述y选自0.01至0.5的范围，可选地选自0.25至0.5的范围；和/或，所述z选自0.001至0.005的范围；和/或，所述n选自0.001至0.005的范围。
  7. 根据权利要求1至6中任一项所述的正极活性材料，其中，(1-y):y在1至4范围 内，可选地在1.5至3范围内，且a:x在9到1100范围内，可选地在190到998范围内。
  8. 根据权利要求1至7中任一项所述的正极活性材料，其中，所述内核的晶格变化率为8％以下，可选地为4％以下。
  9. 根据权利要求1至8中任一项所述的正极活性材料，其中，所述正极活性材料的Li/Mn反位缺陷浓度为2％以下，可选地为0.5％以下。
  10. 根据权利要求1至9中任一项所述的正极活性材料，其中，所述正极活性材料表面氧价态为-1.82以下，可选地为-1.89～-1.98。
  11. 根据权利要求1至7中任一项所述的正极活性材料，其中，所述正极活性材料在3T下的压实密度为2.0g/cm 3以上，可选地为2.2g/cm 3以上。
  12. 一种权利要求1至11中任一项所述的正极活性材料的制备方法，所述制备方法包括以下步骤：
    (1)将锰源、元素B的源和酸在溶剂中溶解并搅拌，生成掺杂元素B的锰盐的悬浊液，将悬浊液过滤并烘干滤饼，得到掺杂了元素B的锰盐；
    (2)将锂源、磷源、元素A的源、元素C的源、元素D的源、碳源、碳层掺杂元素的源、溶剂和由步骤(1)获得的掺杂了元素B的锰盐加入反应容器中研磨并混合，得到浆料；
    (3)将由步骤(2)获得的浆料转移到喷雾干燥设备中进行喷雾干燥造粒，得到颗粒；
    (4)将由步骤(3)获得的颗粒进行烧结，得到所述正极活性材料。
  13. 根据权利要求12所述的制备方法，其中，
    所述元素A的源选自元素A的单质、氧化物、磷酸盐、草酸盐、碳酸盐和硫酸盐组成的组中的至少一种，
    所述元素B的源选自元素B的单质、氧化物、磷酸盐、草酸盐、碳酸盐和硫酸盐组成的组中的至少一种，
    所述元素C的源选自元素C的硫酸盐、硼酸盐、硝酸盐和硅酸盐组成的组中的至少一种，
    所述元素D的源选自元素D的单质和铵盐组成的组中的至少一种，
    所述碳源选自淀粉、蔗糖、葡萄糖、纤维素、聚乙烯醇、聚乙二醇、羧甲基纤维素钠、柠檬酸、乳酸、琥珀酸组成的组中的一种或多种，
    所述碳层掺杂元素的源选自氮元素的源、磷元素的源、硫元素的源、硼元素的源、氟元素的源组成的组中的一种或多种，
    所述氮元素的源选自乙二胺、三聚氰胺、苄胺、乙腈、氨化蔗糖、吡咯、苯胺、丙烯腈、聚酰亚胺酸、含氮脂杂环化合物组成的组中的任意一种或多种；
    所述磷元素的源选自单质磷、五氧化二磷、磷酸二氢铵、磷酸铵、磷酸、次磷酸、亚磷酸、偏磷酸、焦磷酸、多聚磷酸、植酸、三氯化磷、五氯化磷、三溴化磷、三苯氧磷、三苯基膦、三丁基膦组成的组中的任意一种或多种；
    所述硫元素的源选自硫粉、硫酸、亚硫酸、硫酸铵、噻吩、噻唑、硫脲、二甲基亚砜、硫代乙酰胺、硫醇组成的组中的任意一种或多种；
    所述硼元素的源选自单质硼、硼酸、三氧化二硼、氮化硼、硼酸三甲酯、四苯基硼酸钠、三氯化硼组成的组中的任意一种或多种；
    所述氟元素的源选自氢氟酸、氟化铵、含氟有机物组成的组中的任意一种或多种，所述含氟有机物选自含氟烷烃、含氟烯烃、含氟芳烃、含氟羧酸中的任意一种。
  14. 一种正极极片，其包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，所述正极膜层包括权利要求1至11中任一项所述的正极活性材料或通过权利要求12或13所述的制备方法制备的正极活性材料，并且所述正极活性材料在所述正极膜层中的含量为10重量％以上，可选地，95重量％至99.5重量％，基于所述正极膜层的总重量计。
  15. 一种二次电池，其中，包括权利要求1至11中任一项所述的正极活性材料或通过权利要求12或13所述的制备方法制备的正极活性材料或权利要求14所述的正极极片。
  16. 一种电池模块，包括二次电池，其中，所述二次电池为权利要求15所述的二次电池。
  17. 一种电池包，包括电池模块，其中所述电池模块为权利要求16所述的电池模块。
  18. 一种用电装置，包括二次电池或电池模块或电池包，其中，所述二次电池选自权利要求15所述的二次电池、所述电池模块为权利要求16所述的电池模块或所述电池包为权利要求17所述的电池包。
PCT/CN2022/094485 2022-05-23 2022-05-23 正极活性材料、其制备方法、正极极片、二次电池、电池模块、电池包和用电装置 WO2023225796A1 (zh)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/CN2022/094485 WO2023225796A1 (zh) 2022-05-23 2022-05-23 正极活性材料、其制备方法、正极极片、二次电池、电池模块、电池包和用电装置
CN202280038504.5A CN117441241A (zh) 2022-05-23 2022-05-23 正极活性材料、其制备方法、正极极片、二次电池、电池模块、电池包和用电装置

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2022/094485 WO2023225796A1 (zh) 2022-05-23 2022-05-23 正极活性材料、其制备方法、正极极片、二次电池、电池模块、电池包和用电装置

Publications (1)

Publication Number Publication Date
WO2023225796A1 true WO2023225796A1 (zh) 2023-11-30

Family

ID=88918150

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2022/094485 WO2023225796A1 (zh) 2022-05-23 2022-05-23 正极活性材料、其制备方法、正极极片、二次电池、电池模块、电池包和用电装置

Country Status (2)

Country Link
CN (1) CN117441241A (zh)
WO (1) WO2023225796A1 (zh)

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040033360A1 (en) * 2000-09-26 2004-02-19 Michel Armand Method for synthesis of carbon-coated redox materials with controlled size
JP2004063422A (ja) * 2002-07-31 2004-02-26 Sony Corp 正極活物質、並びに非水電解質電池
CN101339994A (zh) * 2008-09-01 2009-01-07 罗绍华 多位掺杂型磷酸铁锂正极材料制备方法及其应用
CN101364643A (zh) * 2008-07-18 2009-02-11 杭州赛诺索欧电池有限公司 一种含硼的磷酸铁锂/炭复合材料及其制备方法
CN103069624A (zh) * 2010-07-01 2013-04-24 夏普株式会社 正极活性材料、正极和非水二次电池
CN106981648A (zh) * 2017-06-05 2017-07-25 东北大学秦皇岛分校 复合正极材料、其制备方法和包含该复合正极材料的锂离子电池
CN108987697A (zh) * 2018-07-12 2018-12-11 西安交通大学 一种高比能量的橄榄石型磷酸锰锂锂离子电池正极材料的制备方法
CN109390563A (zh) * 2017-08-03 2019-02-26 宁德新能源科技有限公司 改性磷酸铁锂正极材料及其制备方法、正极片、锂二次电池

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040033360A1 (en) * 2000-09-26 2004-02-19 Michel Armand Method for synthesis of carbon-coated redox materials with controlled size
JP2004063422A (ja) * 2002-07-31 2004-02-26 Sony Corp 正極活物質、並びに非水電解質電池
CN101364643A (zh) * 2008-07-18 2009-02-11 杭州赛诺索欧电池有限公司 一种含硼的磷酸铁锂/炭复合材料及其制备方法
CN101339994A (zh) * 2008-09-01 2009-01-07 罗绍华 多位掺杂型磷酸铁锂正极材料制备方法及其应用
CN103069624A (zh) * 2010-07-01 2013-04-24 夏普株式会社 正极活性材料、正极和非水二次电池
CN106981648A (zh) * 2017-06-05 2017-07-25 东北大学秦皇岛分校 复合正极材料、其制备方法和包含该复合正极材料的锂离子电池
CN109390563A (zh) * 2017-08-03 2019-02-26 宁德新能源科技有限公司 改性磷酸铁锂正极材料及其制备方法、正极片、锂二次电池
CN108987697A (zh) * 2018-07-12 2018-12-11 西安交通大学 一种高比能量的橄榄石型磷酸锰锂锂离子电池正极材料的制备方法

Also Published As

Publication number Publication date
CN117441241A (zh) 2024-01-23

Similar Documents

Publication Publication Date Title
WO2023066393A1 (zh) 正极活性材料、正极极片、二次电池、电池模块、电池包和用电装置
WO2023082182A1 (zh) 正极活性材料、正极极片、二次电池、电池模块、电池包和用电装置
WO2023066394A1 (zh) 正极活性材料、正极极片、二次电池、电池模块、电池包和用电装置
WO2023206397A1 (zh) 二次电池、电池模块、电池包和用电装置
WO2023065359A1 (zh) 正极活性材料、正极极片、二次电池、电池模块、电池包和用电装置
WO2023206342A1 (zh) 二次电池以及包含其的电池模块、电池包及用电装置
WO2023184355A1 (zh) 正极活性材料、其制备方法以及包含其的正极极片、二次电池及用电装置
WO2023225796A1 (zh) 正极活性材料、其制备方法、正极极片、二次电池、电池模块、电池包和用电装置
WO2023184496A1 (zh) 二次电池、电池模块、电池包和用电装置
WO2023184294A1 (zh) 正极极片、二次电池、电池模块、电池包和用电装置
WO2023164931A1 (zh) 正极极片、二次电池、电池模块、电池包和用电装置
WO2023225836A1 (zh) 正极活性材料、正极极片、二次电池、电池模块、电池包和用电装置
WO2023184511A1 (zh) 正极活性材料、其制备方法以及包含其的正极极片、二次电池及用电装置
WO2023184494A1 (zh) 正极活性材料、其制备方法以及包含其的正极极片、二次电池及用电装置
WO2023240617A1 (zh) 具有核-壳结构的正极活性材料及制备方法、正极极片、二次电池、电池模块、电池包和用电装置
WO2023245345A1 (zh) 一种具有核-壳结构的正极活性材料、其制备方法、正极极片、二次电池、电池模块、电池包及用电装置
WO2023225838A1 (zh) 正极活性材料、正极极片、二次电池、电池模块、电池包和用电装置
WO2024065213A1 (zh) 正极活性材料、其制备方法以及包含其的正极极片、二次电池及用电装置
WO2023184512A1 (zh) 正极活性材料、其制备方法以及包含其的正极极片、二次电池及用电装置
WO2023184367A1 (zh) 一种正极极片、二次电池、电池模块、电池包和用电装置
WO2023184502A1 (zh) 正极活性材料、其制备方法以及包含其的正极极片、二次电池及用电装置
WO2023206421A1 (zh) 二次电池以及包含其的电池模块、电池包及用电装置
WO2024020795A1 (zh) 一种复合正极材料、其制备方法、二次电池、电池模块、电池包和用电装置
WO2023164930A1 (zh) 新型正极极片、二次电池、电池模块、电池包及用电装置
WO2023184304A1 (zh) 新型正极极片、二次电池、电池模块、电池包及用电装置

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 22943008

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 2022943008

Country of ref document: EP

ENP Entry into the national phase

Ref document number: 2022943008

Country of ref document: EP

Effective date: 20240325