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WO2024046046A1 - 一种正极活性材料及其应用 - Google Patents

一种正极活性材料及其应用 Download PDF

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Publication number
WO2024046046A1
WO2024046046A1 PCT/CN2023/111591 CN2023111591W WO2024046046A1 WO 2024046046 A1 WO2024046046 A1 WO 2024046046A1 CN 2023111591 W CN2023111591 W CN 2023111591W WO 2024046046 A1 WO2024046046 A1 WO 2024046046A1
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WIPO (PCT)
Prior art keywords
lithium
active material
cathode
cathode active
ion battery
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Application number
PCT/CN2023/111591
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English (en)
French (fr)
Inventor
曾家江
夏定国
李素丽
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珠海冠宇电池股份有限公司
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Publication of WO2024046046A1 publication Critical patent/WO2024046046A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to a pole piece material, in particular to a cathode active material and its application, and belongs to the technical field of secondary batteries.
  • the capacity of the positive active material plays a crucial role in the capacity of the lithium-ion battery.
  • the most commonly used method at present is to increase its charge and discharge voltage.
  • the crystal structure of the positive active material will collapse, which will lead to a series of problems such as rapid capacity fading and a significant reduction in cycle performance of the battery.
  • This application provides a cathode active material.
  • the special composition and crystal phase structure of the cathode active material help to improve the specific capacity and cycle performance of the battery. Especially under high-voltage conditions, the battery can still perform well.
  • the present application provides a positive electrode sheet, which includes the above-mentioned positive electrode active material, thereby helping to improve the relevant electrical performance of the battery.
  • This application also provides a lithium-ion battery, which includes the above-mentioned positive electrode sheet. Therefore, the lithium-ion battery has excellent performance in terms of specific capacity and cycle performance.
  • the present application provides a cathode active material, which includes a lithium metal oxide represented by Formula 1 or Formula 2;
  • the lithium metal oxide is in the Cmca space group of the cubic crystal system, and has a 002 peak with a 2 ⁇ of 17.9°-18.1°, and a 131 peak with a 2 ⁇ of 67.0°-67.5°; Li n1- y1 Na y1 Co 1-a1-b1 M1 b1 M2 a1 O 2Formula 1Li n2-y2-b2 Na y2 Co 1-a2 M1 b2 M2 a2 O 2Formula 2
  • M1 is selected from at least one of Te, W, Al, B, P and K; M2 is a doping element.
  • M1 is selected from one of Al, W and/or Te, B and/or P;
  • M1 is K.
  • cathode active material as described above, wherein the cathode active material is composed of a core including the lithium metal oxide and a coating layer covering at least part of the surface of the core.
  • the first-stage discharge capacity ratio of the positive active material is C1/C0 ⁇ 9%, and the second-stage discharge capacity ratio is C2/C0 ⁇ 25%;
  • C0 is the discharge capacity of the half-cell including the positive active material when the discharge process is performed at a voltage of 3.0 to 4.55V; in the discharge process, the capacity released when the half-cell is discharged from the initial discharge voltage to 4.4V It is defined as C1, and the capacity released when the half-cell is discharged from 3.8V to 3.7V is defined as C2.
  • the present application provides a cathode sheet, which includes the cathode active material described in any one of the above.
  • the cathode active layer contains 70-99wt% cathode active material, 0.5 -15wt% conductive agent, 0.5-15wt% binder.
  • the positive electrode active layer includes 80-98wt% positive electrode active material, 1-10wt% conductive agent, and 1-10wt% binder according to mass percentage.
  • the present application provides a lithium ion battery, which includes a positive electrode sheet as described above.
  • the negative electrode sheet is a lithium foil.
  • the negative electrode sheet includes a stacked negative electrode current collector and a negative electrode active layer and a lithium material layer arranged on at least one surface of the negative electrode current collector, and the negative electrode active layer is close to the Negative current collector.
  • the areal density of metallic lithium in the lithium material layer is 0.09 mg/cm 2 to 3.5 mg/cm 2 .
  • the negative active layer includes 70-99wt% negative active material, 0.5-15wt% conductive agent, and 0.5-15wt% binder in terms of mass percentage.
  • the negative active layer includes 80-98wt% negative active material, 1-10wt% conductive agent, and 1-10wt% binder in terms of mass percentage.
  • the cathode active material of this application has a special crystal phase structure and chemical composition. After it is used in a battery, the cycle performance and gram capacity of the battery are significantly improved. Even under high-voltage conditions of 4.5V and above, the cathode active material is used The battery can still maintain excellent electrical performance and will not suffer from structural collapse due to poor voltage resistance of the positive active material.
  • Figure 1 is a partial structural schematic diagram of an embodiment of the negative electrode sheet in the lithium ion battery of the present invention.
  • Figure 2 is the XRD pattern of sample 1A# in Example 1A of the present invention.
  • Figure 3 is an SEM image of sample 1C# in Example 1C of the present invention.
  • Figure 4 is an SEM image of sample 3C# in Example 3C of the present invention.
  • Figure 5 is a cycle performance comparison curve of sample 1D# in Example 1D of the present invention and the sample in Comparative Example 3.
  • a first aspect of the present application provides a cathode active material, which includes a lithium metal oxide represented by Formula 1 or Formula 2;
  • the lithium metal oxide is in the Cmca space group of the cubic crystal system, and has a 002 peak with a 2 ⁇ of 17.9°-18.1°, and a 131 peak with a 2 ⁇ of 67.0°-67.5°; Li n1- y1 Na y1 Co 1-a1-b1 M1 b1 M2 a1 O 2Formula 1Li n2-y2-b2 Na y2 Co 1-a2 M1 b2 M2 a2 O 2Formula 2
  • M1 is selected from at least one of Te, W, Al, B, P and K; M2 is a doping element different from M1.
  • the lithium metal oxide mentioned above in this application is a compound with a T2 phase stacking structure, specifically an oxide including at least lithium, sodium and M1. Furthermore, it can also be doped with M2. This application does not limit the specific selection of M2, and it can be a common doping element in the art. For example, it may be at least one of Mg, Ti, Mn, Al, Te, W, Ni, Nb, Zr, La, F, Ce, Sr, Y, K, B and P elements.
  • y1 is 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.010, 0.012, 0.015, 0.018, 0.020, 0.022, 0.024, 0.025, 0.026, 0.028, 0.03, 0.
  • a1 is 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.010, 0.012, 0.015, 0.018, 0.020, 0.022, 0.024, 0.025, 0.026, 0.028, 0.030, 0.032, 0 .034, 0.035, 0.04, 0.045, 0.05, 0.055, 0.06, 0.065, 0.07, 0.075, 0.08, 0.085, 0.09 or 0.095;
  • b1 is 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.010, 0.012, 0.015 ,0.018,0.020,0.022, 0.024, 0.025, 0.026, 0.028, 0.030, 0.032, 0.034, 0.035, 0.04, 0.045, 0.05, 0.055, 0.06, 0.065, 0.07, 0.075, 0.08, 0.085, 0.09 or 0.095;
  • y2 is 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.010, 0.012, 0.015, 0.018, 0.020, 0.022, 0.024, 0.025, 0.026, 0.028, 0.03, 0.0 4 or 0.05;
  • a2 is .001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.010, 0.012, 0.015, 0.018, 0.020, 0.022, 0.024, 0.025, 0.026, 0.028, 0.030, 0.032, 0.03 4.
  • b2 is 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.010, 0.012, 0.015, 0.0 18,0.02.
  • a2/1-a2 is 0.005, 0.01, 0.02, 0.03, 0.04, 0.06, 0.08, 0.09, 0.095 or 0.1.
  • n1 and n2 refer to parameters related to the molar amount of lithium per unit mole of lithium metal oxide in the cathode active material that has not undergone any charge and discharge treatment. It can be understood that when the positive active material is applied to a lithium-ion battery for any charge and discharge process, the molar amount of lithium in a unit mole of lithium metal oxide is different under different charge and discharge mechanisms and charge and discharge nodes.
  • the cathode active material including the lithium metal oxide is applied to a lithium-ion battery, the specific capacity and cycle performance of the lithium-ion battery are significantly improved, even at high voltage. Under operating conditions, the electrical performance of lithium-ion batteries will not deteriorate. Based on the analysis of this phenomenon, the inventor believes that: on the one hand, the doping of M1 helps to support the structure of lithium metal oxide, which improves the structural stability of lithium metal oxide to a certain extent.
  • the structurally stable lithium metal oxide is more helpful to improve the efficiency of lithium ion deintercalation and promote the improvement of lithium-ion battery cycle performance and specific capacity; on the other hand, it has the above crystal characteristics
  • the lithium metal oxide has a more complete layered crystal phase structure, which can reduce or inhibit the occurrence of internal mixing of the crystal phase, thereby enabling smooth deintercalation of lithium ions, especially during high-voltage charge and discharge processes. Multiple small charging and discharging platforms are developed.
  • M1 in Formula 1 is selected from one of Al, W and/or Te, B and/or P (that is, M1 is selected from Al, W, Te, a blend of W and Te, B, P, B Any blend with P); M1 in formula 2 is K. Specifically, when M1 in Formula 1 and Formula 2 is selected from different doping elements, there are certain differences in the degree of improvement in the electrical properties related to lithium metal oxide.
  • M1 in Formula 1 contains one of Al, Te and/or W and P
  • Al atoms, Te atoms and/or W atoms and P atoms can replace Co in the lithium metal oxide. atoms, thereby improving the structural stability of lithium metal oxide, allowing the lithium metal oxide under high pressure to successfully complete the deintercalation of lithium ions without structural collapse, improving the specific capacity and cycle performance of the battery;
  • M1 in Formula 1 contains B atoms
  • the insertion of B atoms can replace the Co atoms in the lithium metal oxide, which has a certain degree of fluxing effect and helps to make the lithium metal oxide a single crystal morphology (i.e., a primary particles), thereby increasing the compaction density of the positive electrode sheet.
  • M1 in Formula 2 is selected from K atoms
  • the radius of K atoms is larger than that of Li atoms and Na atoms.
  • the K atoms occupy a supporting role in the lithium metal oxide, which is beneficial to the deintercalation of Li ions, thereby benefiting the cycle performance. and a significant increase in gram capacity.
  • the doping amount of K by controlling the doping amount of K, the electrochemical kinetic performance and rate performance during the battery charge and discharge process can be improved, and the polarization phenomenon can be reduced, which also has a positive effect on the rate performance and first effect.
  • the positive active material has a core-shell structure including a core of lithium metal oxide and the coating layer covering the core.
  • This coating helps to reduce or inhibit the side reactions of lithium metal oxide and electrolyte. Even when the battery is operating in a high-pressure environment, a stable interface can still be formed between the positive active material and the electrolyte.
  • the cycle performance of the battery is improved by the transitional dissolution of metal ions in the ions and the avoidance of liquid shortage. At the same time, the suppression or reduction of side reactions can also reduce the amount of gas produced inside the battery, thus ensuring the safety performance of the battery.
  • the coating layer can be made of carbon-containing compounds, fast ion conductors and other materials.
  • n1 and n2 are between 0.6 and 0.8.
  • the positive electrode sheet including the positive electrode active material and the lithium metal negative electrode sheet are assembled into a battery and then charged and discharged, when the remaining power SOC of the battery is 0 (that is, it is in a fully discharged state) and the discharge cut-off voltage is 3.0 ⁇ 3.6V, lithium n1 and n2 of metal oxides are between 0.7 and 1.0.
  • the changes in n1 and n2 refer to the number of charge and discharge cycles being within 10. Specifically, after the aforementioned lithium metal oxide is charged and discharged, its composition will change, especially the molar amount of lithium will increase significantly.
  • the lithium metal oxide with the aforementioned crystal structure has some vacancies. Therefore, when it is subjected to charge and discharge processing (such as chemical formation), its vacancies can accept lithium atoms from the lithium negative electrode, thereby increasing the mole of lithium ions.
  • the capacity is improved compared with before charge and discharge use. This feature helps further improve the cycle performance and specific capacity of the battery.
  • n1 and n2 can be performed by ICP. Specifically, the discharged battery is disassembled and the positive electrode sheet is taken out. Soak in dimethyl carbonate (DMC) for 1-3 hours or rinse with DMC. After natural drying in the drying room, place it in a muffle furnace for roasting at 300-600°C for 2-5 hours, and sieve with 200 mesh to obtain the powder to be tested. The metal elements in the powder to be detected are then detected through ICP, and n1 and n2 are calculated.
  • DMC dimethyl carbonate
  • the cathode active material of the present application can be in a single crystal morphology or a polycrystalline morphology, and the specific morphology is related to the selection and proportion of its doping elements. Specifically, when it is a polycrystalline morphology, it is a spherical or spherical-like particle; when it is a single crystal morphology, it can be a whisker, a flake, or any other irregular shape.
  • the median particle diameter of the cathode active material of the present application is 12-20 ⁇ m, such as 3 ⁇ m, 14 ⁇ m, 15 ⁇ m, 16 ⁇ m, 17 ⁇ m, 18 ⁇ m, 19 ⁇ m or 20 ⁇ m.
  • the inventor found that when the median particle size of the positive electrode active material meets the above requirements, on the one hand, its corresponding specific surface area can meet the deintercalation of more lithium ions; on the other hand, the agglomeration phenomenon between the positive electrode active materials is effectively controlled. , so that it can be stably dispersed in the slurry during the pulping process.
  • the first-stage discharge capacity of the cathode active material accounts for C1/C0 ⁇ 9%, and the second-stage discharge capacity accounts for C2/C0 ⁇ 25%; wherein, C0 includes the cathode active material
  • C1 includes the cathode active material
  • the capacity released when V is discharged to 3.7V is defined as C2.
  • the above discharge capacity is performed under a special discharge mechanism. Specifically, after the half-battery composed of the positive electrode sheet of the positive electrode active material and the lithium metal negative electrode is charged until the SOC is 100% (the charging mechanism is not particularly limited), it is discharged at 0.1C at 3.0-4.55V. Among them, when discharging from 4.55V to 4.4V at 0.1C, the amount of electricity released is C1, and continuing to discharge. When discharging from 3.8V to 3.7V, the amount of electricity released in the step-down stage is C2, and continues to discharge to 3.0V (at this time, the SOC is 0), the total amount of electricity initially released by self-discharge is C0.
  • the cathode active material including the lithium metal oxide of the present application has strong voltage resistance, so that the specific capacity of the battery can be increased by subjecting it to a voltage boosting process.
  • the peak intensity of the 002 peak is I1
  • the peak intensity of the 131 peak is I2
  • I1/I2 ⁇ 4 the internal crystal structure of lithium metal oxidation is more complete, which helps to improve the battery cycle performance. Further, I1/I2 ⁇ 6.
  • the lithium metal oxide of the present application can be prepared by mixing the sodium metal oxide represented by formula 1a or 2a with a lithium compound and subjecting it to ion treatment prepared by the method.
  • the above-mentioned ion exchange treatment is a heat treatment process, which specifically refers to mixing sodium metal oxide and lithium compound and then performing heat treatment at 80°C to 300°C for no more than 10 hours. After the ion exchange treatment, the ion exchanged system is washed and dried to finally obtain lithium metal oxide. Among them, the drying temperature is 80-180°C and the drying time is at least 10 hours.
  • the equipment and drying equipment for ion exchange treatment can be a closed container equipment with sealing function and stirring ability, such as wet coating reaction equipment, co-precipitation reaction equipment, etc.; drying equipment It can be a blast oven, vacuum drying oven, rotary kiln, plate dryer, oven, etc.
  • the above-mentioned lithium compound may be a lithium source compound commonly used in the art, such as at least one of lithium carbonate, lithium chloride, lithium bromide, lithium iodide, lithium nitrate, lithium hydroxide, and lithium fluoride.
  • the mass ratio of the lithium compound and the sodium metal oxide is not less than 1:1, preferably (1-3):1.
  • a coating layer raw material needs to be added during the ion exchange process.
  • sodium metal compound represented by Formula 1a and Formula 2a for example, it can be prepared by a method including the following process:
  • the cobalt source, sodium source, M1 source and M2 source are mixed according to the target proportion and then calcined to obtain the sodium metal compound represented by formula 1a and formula 2a.
  • the temperature of the calcination treatment is 700 to 900°C, and the time is 8 to 50 hours.
  • the calcination treatment can be performed in an oxygen or air atmosphere.
  • the equipment for the calcination treatment may be, for example, high-temperature sintering equipment such as muffle furnaces, tunnel furnaces, roller kilns, and tube furnaces.
  • each of the above sources can be performed by high-speed mixing equipment, sand grinding equipment, ball milling equipment, plow mixing equipment, inclined mixing equipment, etc. It should be noted that if sand grinding equipment, ball milling equipment and ball milling or When adding solvent (water, ethanol or other solvent media) during the sanding process, the mixed system needs to be dried after the mixing process is completed. Generally, the mixing time is no longer than 4 hours.
  • cobalt source is selected from one or more of cobalt hydroxide, cobalt tetroxide, doped cobalt tetroxide, cobalt oxide, cobalt oxyhydroxide, cobalt nitrate, cobalt sulfate, etc.
  • the sodium source is selected from sodium carbonate, sodium nitrate , sodium hydroxide, sodium bicarbonate, sodium sulfate, etc.
  • the M1 source can be any compound containing M1, such as the oxide of M1.
  • the M1 source is, for example, tungstic acid and/or Or sodium tungstate, etc.; when M1 is Te, the M1 source is, for example, telluric acid and/or sodium tellurate, etc.; when M1 is Al, the M1 source is, for example, one of aluminum sulfate, aluminum nitrate, aluminum hydroxide, etc.
  • M1 when M1 is B, the M1 source is, for example, boric acid and/or sodium borate, etc.; when M1 is P, the M1 source is, for example, phosphoric acid and/or sodium phosphate, etc.; when M1 is K, the M1 source is, for example, One or more of potassium carbonate, potassium nitrate, potassium hydroxide, potassium bicarbonate, potassium sulfate, etc.; the source of M2 can be any compound containing M2, such as the oxide of M2, such as basic magnesium carbonate, hydrogen One or more of magnesium oxide, zirconium oxide, yttrium oxide, lanthanum oxide, lanthanum fluoride, nickel oxide, niobium oxide, etc.
  • a second aspect of the present application provides a cathode sheet, which includes the cathode active material described in the first aspect.
  • the cathode sheet of the present application helps to improve the cycle performance and specific capacity of the lithium-ion battery.
  • the cathode sheet of the present application includes a cathode current collector and a cathode active layer disposed on at least one surface of the cathode current collector.
  • the cathode active layer includes the aforementioned cathode active material.
  • the positive active layer also includes a conductive agent and a binder.
  • the cathode active layer includes 70-99wt% cathode active material, 0.5-15wt% conductive agent, 0.5-15wt% binder in terms of mass percentage, and further includes 80-98wt% cathode activity Material, 1-10wt% conductive agent, 1-10wt% binder.
  • the selection of conductive agent and binder is not special and can be conventionally selected in this field.
  • the conductive agent is selected from at least one of conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes, single-wall carbon nanotubes, multi-arm carbon nanotubes, and carbon fibers
  • the binder is selected from the group consisting of: From at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and polyacrylic lithium (PAALi).
  • a safety layer can also be provided between the positive electrode active layer and the current collector.
  • the material of the safety layer is generally a non-conductive safety material, such as iron-containing compounds (such as lithium iron phosphate, lithium phosphate, etc.), aluminum-containing compounds (such as ceramic alumina), etc.
  • the security layer also includes adhesive, and the ratio of adhesive and security material can be further determined according to specific needs.
  • the third aspect of the present application also provides a lithium-ion battery.
  • the ion battery includes the above-mentioned positive electrode sheet and therefore has outstanding performance in terms of cycle performance and specific capacity.
  • This application does not limit the specific structure of the lithium-ion battery.
  • it may be a square-shell battery, a cylindrical battery, etc.
  • the lithium-ion battery also includes a negative electrode sheet, a separator and an electrolyte.
  • the electrolyte is a conventional electrolyte known in the art including lithium salts and solvents.
  • the solvent contains ethylene carbonate (abbreviated as EC), diethyl carbonate (abbreviated as DEC), propylene carbonate (abbreviated as PC). ), fluoroethylene carbonate (abbreviated as FEC).
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • FEC fluoroethylene carbonate
  • an additive represented by formula T is also included, the mass percentage of which is 0.1 to 10% in the electrolyte.
  • the negative electrode sheet may be a negative electrode sheet containing lithium metal, such as a lithium foil or a negative electrode sheet as shown in FIG. 1 .
  • the negative electrode sheet in FIG. 1 includes a stacked negative electrode current collector 101, a negative electrode active layer 20, and a lithium material layer 30.
  • the negative electrode sheet in FIG. 1 is provided on both sides.
  • it may also be a negative electrode sheet in which the negative electrode active layer 20 and the lithium material layer 30 are provided on only one side of the negative electrode current collector.
  • the lithium material layer is, for example, lithium foil.
  • the areal density of metallic lithium in the lithium material layer is 0.09 mg/cm 2 to 3.5 mg/cm 2 ; the negative electrode active layer includes a negative electrode active material, a conductive agent, and a binder.
  • the negative active layer includes 70-99wt% negative active material, 0.5-15wt% conductive agent, 0.5-15wt% binder according to mass percentage, and further includes 80-98wt % negative active material, 1-10wt% conductive agent, 1-10wt% binder.
  • the negative active material is selected from one or more of artificial graphite, natural graphite, hard carbon, mesocarbon microspheres, lithium titanate, silicon carbon, and silicon oxide.
  • the separator is a polypropylene-based material, or a rubber-coated separator coated with ceramic on one or both sides.
  • the lithium-ion battery of the present application is suitable for high-voltage systems. Specifically, under the condition that the lithium-ion button battery including the aforementioned positive electrode sheet is ⁇ 4.55V (relative to lithium), the gram capacity of the positive electrode sheet is ⁇ 225mAh/g, and at ⁇ 4.50 V (corresponding to the aforementioned negative electrode sheet) also has excellent cycle performance.
  • the lithium-ion battery of this application has good cycle stability and high gram capacity at higher voltages such as 4.50V, which can meet the needs of high-end digital products to be thinner and lighter.
  • cathode active material of the present application is introduced through specific examples.
  • sample 1A# was obtained after drying at 90°C for 8 hours.
  • Figure 2 is the XRD pattern of sample 1A# in Example 1A of the present application.
  • the lithium metal oxide prepared in this embodiment has a 002 peak and a 131 peak, and is in the Cmca space group of the cubic crystal system and has a T2 structure.
  • Examples 2A-9A are basically the same as those of Example 1A. The only difference lies in the selection of different M1 (W source or Te source) and M2 sources in step (1), and the quality of each metal source. Ratio, the specific selection is shown in Table 1A, and finally samples 2A#-9A# were obtained, and the ICP detection and analysis results are shown in Table 1A.
  • Example 10A The preparation method of Example 10A is basically the same as that of Example 1A. The only difference is that step (1) is: weighing 36.56g of sodium carbonate powder, weighing 4.593g of telluric acid powder, and weighing 79.30g.
  • step (1) is: weighing 36.56g of sodium carbonate powder, weighing 4.593g of telluric acid powder, and weighing 79.30g.
  • the compound of aluminum doped with cobalt tetroxide (Co 0.95 Al 0.03 ) 3 O 4 has been put into the high-speed mixing equipment, and the mixing program is set. After mixing at 300 rpm for 3 minutes, then at 500 rpm for 5 minutes, and then at 1000 rpm. After mixing for 10 minutes, take out the mixture and confirm that there are no white sodium carbonate spots in the mixture. The mixture is considered to be uniform;
  • the sodium metal oxide obtained in the final step 2) is Na 0.69 Co 0.95 Te 0.02 Al 0.03 O 2 and the 10A# sample is Li 0.71 Na 0.02 Co 0.95 Te 0.02 Al 0.03 O 2 .
  • Example 11A The preparation method of Example 11A is basically the same as the preparation method of Example 10A. The only difference is that step (3) is: take a reaction vessel and first weigh 10.49g of lithium hydroxide monohydrate and 17.24g of lithium hydroxide. Lithium nitrate particles, add the two lithium compounds into the reaction vessel respectively, weigh 10g of the Na 0.69 Co 0.95 Te 0.02 Al 0.03 O 2 synthesized in step (2), pour it into the reaction vessel, and after preliminary mixing, place it at 280 °C ion exchange for 1 hour to obtain a crude product; after the treatment in step (4), sample 11A#Li 0.71 Na 0.02 Co 0.95 Te 0.02 Al 0.03 O 2 was obtained.
  • Example 12A The preparation method of Example 12A is basically the same as the preparation method of Example 10A. The only difference is that step (3) is: take a reaction vessel and first weigh 10.49g of lithium hydroxide monohydrate and 9.24g of lithium hydroxide. Lithium carbonate particles, add the two lithium compounds into the reaction vessel respectively, weigh 10g of the Na 0.69 Co 0.95 Te 0.02 Al 0.03 O 2 synthesized in step (2), pour it into the reaction vessel, and after preliminary mixing, place it at 280 °C ion exchange for 0.5h to obtain the crude product; after the treatment in step (4), sample 12A#Li 0.71 Na 0.0.02 Co 0.95 Te 0.02 Al 0.03 O 2 was obtained.
  • Example 13A The preparation method of Example 13A is basically the same as the preparation method of Example 10A. The only difference is that step (3) is: take a reaction vessel and weigh 10.49g of lithium hydroxide monohydrate and 10.59g of lithium hydroxide. Lithium chloride particles, add the two lithium compounds into the reaction vessel respectively, weigh 10g of the Na 0.69 Co 0.95 Te 0.02 Al 0.03 O 2 synthesized in step (2), pour it into the reaction vessel, and after preliminary mixing, Ion exchange was carried out at 280°C for 0.5h to obtain the crude product; after the treatment in step (4), sample 13A#Li 0.71 Na 0.0.02 Co 0.95 Te 0.02 Al 0.03 O 2 was obtained.
  • sample 1B# was obtained after drying at 90°C for 8 hours.
  • Example 2B-9B The preparation method of Examples 2B-9B is basically the same as that of Example 1B. The only difference lies in the selection of different M2 sources in step (1) and the mass ratio between each metal source. The specific selections are shown in Table 1B. Finally Samples 2B#-9B# were obtained, and the ICP detection and analysis results are shown in Table 1B.
  • Example 10B The preparation method of Example 10B is basically the same as that of Example 1B. The only difference is that step (1) is: weighing 36.56g of sodium carbonate powder, weighing 79.30g of aluminum-doped cobalt tetraoxide. Compound (Co 0.95 Al 0.03 ) 3 O 4 , put it into the high-speed mixing equipment, set the mixing program, mix at 300rpm for 3 minutes, mix at 500rpm for 5 minutes, then mix at 1000rpm for 10 minutes, take out and mix After confirming that there are no white sodium carbonate spots in the mixture, the mixture is considered to be uniform;
  • the sodium metal oxide obtained in the final step 2) is Na 0.69 Co 0.97 Al 0.03 O 2 and the 10B# sample is Li 0.71 Na 0.02 Co 0.97 Al 0.03 O 2 .
  • Example 11B The preparation method of Example 11B is basically the same as that of Example 10B, except that the ion exchange time in step (3) is 1 hour.
  • the obtained sample 11B# is Li 0.71 Na 0.02 Co 0.97 Al 0.03 O 2 .
  • Example 12B The preparation method of Example 12B is basically the same as that of Example 10B, except that in step (3), 9.24g of lithium carbonate particles are used to replace 17.24g of lithium nitrate particles.
  • the obtained sample 12B# is Li 0.71 Na 0.02 Co 0.97 Al 0.03 O 2 .
  • Example 13B The preparation method of Example 13B is basically the same as that of Example 10B, except that in step (3), 10.59g of lithium chloride particles are used to replace 17.24g of lithium nitrate particles.
  • the obtained sample 13B# is Li 0.71 Na 0.02 Co 0.97 Al 0.03 O 2 .
  • Figure 3 is an SEM image of sample 1C# in Example 1C of the present application.
  • the preparation method of Examples 2C-9C is basically the same as the preparation method of Example 1C.
  • the only difference lies in the selection of different M1 (B source or P source) and M2 sources in step (1), and the quality of each metal source. Ratio, the specific selection is shown in Table 1C, and finally samples 2C#-9C# were obtained, and the ICP detection and analysis results are shown in Table 1C.
  • Figure 4 is an SEM image of sample 3C# in Example 3C of the present application.
  • Example 10C The preparation method of Example 10C is basically the same as that of Example 1C. The only difference is that step (1) is: weighing 36.56g of sodium carbonate powder, weighing 1.236g of boric acid powder, and weighing 79.30g of sodium carbonate powder.
  • step (1) is: weighing 36.56g of sodium carbonate powder, weighing 1.236g of boric acid powder, and weighing 79.30g of sodium carbonate powder.
  • the sodium metal oxide obtained in the final step 2) is Na 0.69 Co 0.95 B 0.02 Al 0.03 O 2 and the 10C# sample is Li 0.71 Na 0.02 Co 0.95 B 0.02 Al 0.03 O 2 .
  • Example 11C The preparation method of Example 11C is basically the same as that of Example 10C, except that the ion exchange time in step (3) is 1 hour.
  • the obtained sample 11C# is Li 0.71 Na 0.02 Co 0.95 B 0.02 Al 0.03 O 2 .
  • Example 12C The preparation method of Example 12C is basically the same as the preparation method of Example 10C. The only difference is that in step (3), 9.24g of lithium carbonate particles are used to replace 17.24g of lithium nitrate particles.
  • the obtained sample 12C# is Li 0.71 Na 0.02 Co 0.95 B 0.02 Al 0.03 O 2 .
  • Example 13C The preparation method of Example 13C is basically the same as the preparation method of Example 10C, except that in step (3), 10.59g of lithium chloride particles are used to replace 17.24g of lithium nitrate particles.
  • the obtained sample 13C# is Li 0.71 Na 0.02 Co 0.95 B 0.02 Al 0.03 O 2 .
  • Examples 2D-9D are basically the same as those of Example 1D. The only difference lies in the selection of different M2 sources in step (1) and the mass ratio between each metal source. The specific selections are shown in Table 1D. Finally Samples 2D#-9D# were obtained, and the ICP detection and analysis results are shown in Table 1D.
  • Example 10D The preparation method of Example 10D is basically the same as that of Example 1D, except that the ion exchange time in step (3) is 1 hour.
  • the obtained sample 10D# is Li 0.71 Na 0.02 K 0.003 Co 0.97 Mg 0.03 O 2 .
  • Example 11D The preparation method of Example 11D is basically the same as that of Example 1D, except that the ion exchange temperature in step (3) is 260°C.
  • the obtained sample 10D# is Li 0.71 Na 0.02 K 0.003 Co 0.97 Mg 0.03 O 2 .
  • Example 12D The preparation method of Example 12D is basically the same as that of Example 1D, except that in step (3), 9.24g of lithium carbonate particles are used to replace 17.24g of lithium nitrate particles.
  • the obtained sample 12D# is Li 0.71 Na 0.02 K 0.003 Co 0.97 Mg 0.03 O 2 .
  • Example 13D The preparation method of Example 13D is basically the same as that of Example 1D, except that in step (3), 10.59g of lithium chloride particles are used to replace 17.24g of lithium nitrate particles.
  • the obtained sample 13D# is Li 0.71 Na 0.02 K 0.003 Co 0.97 Mg 0.03 O 2 .
  • Table 1D The unfilled parts in Tables 1A-1D represent that the compound is not included in the raw materials of this example.
  • the chemical composition of the cathode active material in this comparative example is Li 1.0026 CoO 2 ;
  • the preparation method includes the following steps:
  • the cathode active material in this comparative example is a conventional high-voltage doped coated lithium cobalt oxide cathode material, and its chemical composition is Li 1.0027 Co 0.97 Al 0.03 O 2 .
  • the preparation method includes the following steps:
  • step (1) is: weigh 36.56g of sodium carbonate powder and 291.05g of cobalt nitrate hexahydrate powder without adding any additives. , put it into the high-speed mixing equipment, set the mixing program, mix at 300rpm for 3 minutes, mix at 500rpm for 5 minutes, and then mix at 1000rpm for 10 minutes. Take out the mixture and confirm that there is no white color in the mixture. After the small white spots of sodium carbonate exist, the mixture is considered uniform;
  • the cathode active material in this comparative example is a conventional high-voltage doped coated lithium cobalt oxide cathode material, and its chemical composition is Li 1.0027 Co 0.947 K 0.003 Mg 0.03 La 0.02 O 2 .
  • the preparation method includes the following steps:
  • a lithium material layer is superimposed on the surface of the negative electrode active layer by rolling.
  • the lithium material layer is lithium foil.
  • the areal density of metallic lithium is 1.0 mg/cm 2 .
  • a negative electrode sheet containing lithium metal is obtained.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • FEC fluoroethylene carbonate
  • LiPF 6 lithium hexafluorophosphate
  • the additive shown in Formula T the additive content accounts for 2% of the total electrolyte content.
  • the capacity retention rate of each obtained lithium-ion battery was tested.
  • the specific test method is: at 25°C, charge with a constant current to 4.50V at a charging rate of 1C, and then charge with a constant voltage to 4.50V at a charging rate of 0.05C. Then discharge to 3.0V at a discharge rate of 1C, repeat this charge and discharge cycle 500 times, measure the discharge capacity at the first cycle and the 500th cycle, and calculate the capacity after 500 cycles according to the following formula Retention rate, the results are shown in Tables 2A ⁇ 2D.
  • Capacity retention rate Q (discharge capacity at the 500th cycle)/(discharge capacity at the first cycle)*100%
  • Figure 5 is a cycle performance comparison curve of sample 1D# in Example 1D of the present application and the sample in Comparative Example 3.
  • the cathode active materials in the examples and comparative examples were mixed with conductive carbon black (SP) and PVDF at a weight ratio of 80%:10%:10%, and then dispersed to obtain a cathode slurry.
  • the slurry is coated on the aluminum foil current collector, and rolled to prepare a positive electrode sheet.
  • the positive electrode sheet is then punched into a small disc with a diameter of 12 mm using a membrane tool. After drying and weighing, the gloves are placed under an Ar protective atmosphere.
  • a 2025 button battery shell is used, a Li metal disc is used as the negative electrode, and a conventional high-voltage lithium cobalt oxide electrolyte is used to assemble a button battery.
  • the first charge and discharge capacity test was performed.
  • the test conditions were: charging from 0.1C to 4.55V, constant voltage charging to 0.025C, and then leaving for 3 minutes. Discharge to 3.0V.
  • the discharge process record the discharge capacity C1 of 4.4-4.55V, the discharge capacity C2 of 3.7-3.8V, the first full discharge capacity C0, and the first charge capacity, and calculate the first efficiency and the first-stage discharge capacity ratio C1/ C0 and the second-stage discharge capacity account for C2/C0.
  • the results are shown in Tables 2A to 2D.
  • Comparative Example 3 has basically the same crystal structure as that of the Examples, there is still a certain gap between the performance in terms of gram capacity and cycle performance and that of the Examples because it is not doped with specific elements. ;
  • Comparative Example 3 has 002 peak and 131 peak, since it does not have M1 doping element, the ratio intensity of its 002 peak and 131 peak is obviously lower, so its performance in terms of cycle performance is not ideal.

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Abstract

一种正极活性材料及其应用，正极活性材料包括锂金属氧化物；在X射线衍射图谱中，锂金属氧化物为立方晶系的Cmca空间群，且具有2θ为17.9°～18.1°的002峰，以及2θ为67.0°～67.5°的131峰。本申请的正极活性材料有利于改善锂离子电池的循环性能和比容量。

Description

一种正极活性材料及其应用
本申请要求于2022年9月2日提交中国专利局、申请号为202211072411.2、申请名称为“一种正极活性材料及其应用”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及一种极片材料，尤其涉及一种正极活性材料及其应用，属于二次电池技术领域。
 背景技术
随着锂离子电池技术的发展和进步，对其容量提出了越来越高的要求。在锂离子电池的组成中，正极活性材料容量的高低，对锂离子电池的容量起着至关重要的作用。
为了提高锂离子电池的容量，目前最常用的方法就是提高其充放电电压。但是随着电压的提高，正极活性材料会出现晶体结构坍塌的现象，进而导致电池出现容量快速衰减和循环性能大幅降低等一系列问题。
因此，开发出一种具有高比容量、循环性能好的锂离子电池正极活性材料是本领域亟待解决的技术问题。
发明内容
本申请提供一种正极活性材料，该正极活性材料特殊的组成以及晶相结构有助于提升电池的比容量以及循环性能，尤其在高压条件下，依旧能够使电池表现优异。
本申请提供一种正极片，该正极片包括上述正极活性材料，因此有助于提升电池的相关电性能。
本申请还提供一种锂离子电池，该锂离子电池包括上述正极片，因此该锂离子电池在比容量和循环性能方面具有优异表现。
本申请提供一种正极活性材料，所述正极活性材料包括式1或式2所示的锂金属氧化物；
在X射线衍射图谱中，所述锂金属氧化物为立方晶系的Cmca空间群，且具有2θ为17.9°～18.1°的002峰，以及2θ为67.0°～67.5°的131峰；Lin1-y1Nay1Co1-a1-b1M1b1M2a1O2     式1Lin2-y2-b2Nay2Co1-a2M1b2M2a2O2     式2
式1中，0.6≤n1≤0.8，0＜y1≤0.05，0≤a1≤0.1，0＜b1≤0.1，0<b1/1-a1-b1<0.1；
式2中，0.6≤n2≤0.8，0＜y2≤0.05，0≤a2≤0.1，0＜b2≤0.02，
其中，M1选自Te、W、Al、B、P以及K中的至少一种；M2为掺杂元素。
如上所述的正极活性材料，其中，式1中，M1选自Al、W和/或Te、B和/或P中的一种；
式2中，M1为K。
如上所述的正极活性材料，其中，所述正极活性材料由包括所述锂金属氧化物的内核和覆盖内核至少部分表面的包覆层构成。
如上所述的正极活性材料，其中，所述正极活性材料在截止电压为3.0～3.6V且SOC为零时，0.7≤n1，n2≤1.0。
如上所述的正极活性材料，其中，所述正极活性材料的中值粒径为12μm～20μm。
如上所述的正极活性材料，其中，
所述正极活性材料的第一阶段放电容量占比C1/C0≥9％，第二阶段放电容量占比C2/C0≥25％；
其中，C0为包括所述正极活性材料的半电池在3.0～4.55V电压下进行放电处理时的放电容量；所述放电处理中，所述半电池由初始放电电压放电至4.4V时放出的容量定义为C1，所述半电池由3.8V放电至3.7V时放出的容量定义为C2。
如上所述的正极活性材料，其中，所述002峰的峰强度为I1，所述131峰的峰强度为I2，且I1/I2≥4。
本申请提供一种正极片，所述正极片包括上述任一项所述的正极活性材料。
如上所述的正极片，其中，所述正极片包括正极集流体和设置在正极集流体至少一表面的正极活性层，所述正极活性层按照质量百分含量70-99wt％正极活性材料、0.5-15wt％导电剂、0.5-15wt％粘结剂。
如上所述的正极片，其中，述正极活性层按照质量百分含量包括80-98wt％正极活性材料、1-10wt％导电剂、1-10wt％的粘结剂。
本申请提供一种锂离子电池，所述锂离子电池包括如上所述的正极片。
如上所述的锂离子电池，其中，所述锂离子电池中的负极片为含锂负极片。
如上所述的锂离子电池，其中，所述负极片为锂箔。
如上所述的锂离子电池，其中，所述负极片包括层叠设置的负极集流体以及设置在所述负极集流体至少一个表面的负极活性层和锂材料层，且所述负极活性层靠近所述负极集流体。
如上所述的锂离子电池，其中，所述锂材料层为锂箔。
如上所述的锂离子电池，其中，所述锂材料层中金属锂的面密度为0.09mg/cm2～3.5mg/cm2。
如上所述的锂离子电池，其中，所述负极活性层按照质量百分含量包括70-99wt％负极活性材料、0.5-15wt％导电剂、0.5-15wt％粘结剂。
如上所述的锂离子电池，其中，所述负极活性层按照质量百分含量包括80-98wt％的负极活性材料、1-10wt％的导电剂、1-10wt％的粘结剂。
本申请的正极活性材料具有特殊晶相结构和化学组成，其在应用于电池中后，电池的循环性能和克容量得到显著提升，即使在4.5V及以上的高压条件下，使用该正极活性材料的电池依旧能够保持相关电性能的优异表现，不会发生由于正极活性材料耐压性差而出现结构坍塌的问题。
 附图说明
[根据细则91更正 25.08.2023]
图1为本发明锂离子电池中的负极片一实施例的部分结构示意图；
[根据细则91更正 25.08.2023]
图2为本发明实施例1A中样品1A#的XRD图；
[根据细则91更正 25.08.2023]
图3为本发明实施例1C中的样品1C#的SEM图；
[根据细则91更正 25.08.2023]
图4为本发明实施例3C中的样品3C#的SEM图；
[根据细则91更正 25.08.2023]
图5为本发明实施例1D中的样品1D#和对比例3中的样品的循环性能比较曲线。
 具体实施方式
为使本申请的目的、技术方案和优点更加清楚，下面将结合本申请的实施例，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
本申请第一方面提供一种正极活性材料，该正极活性材料包括式1或式2所示的锂金属氧化物；
在X射线衍射图谱中，所述锂金属氧化物为立方晶系的Cmca空间群，且具有2θ为17.9°～18.1°的002峰，以及2θ为67.0°～67.5°的131峰；Lin1-y1Nay1Co1-a1-b1M1b1M2a1O2     式1Lin2-y2-b2Nay2Co1-a2M1b2M2a2O2    式2
式1中，0.6≤n1≤0.8，0＜y1≤0.05，0≤a1≤0.1，0＜b1≤0.1，0<b1/1-a1-b1<0.1；
式2中，0.6≤n2≤0.8，0＜y2≤0.05，0≤a1≤0.1，0＜b2≤0.02；
其中，M1选自Te、W、Al、B、P以及K中的至少一种；M2为不同于M1的掺杂元素。
本申请上述的锂金属氧化物是一种具有T2相堆积结构的化合物，具体是至少包括锂、钠以及M1的氧化物。进一步地，其还可以掺杂M2，本申请不限定M2的具体选择，可以为本领域常见的掺杂元素。例如可以是Mg、Ti、Mn、Al、Te、W、Ni、Nb、Zr、La、F、Ce、Sr、Y、K、B和P元素中的至少一种。
本申请对在上述限定范围内的y1、y2、a1、a2、b1、b2等不做过多限制。
例如，式1中，y1为0.001、0.002、0.003、0.004、0.005、0.006、0.007、0.008、0.010、0.012、0.015、0.018、0.020、0.022、0.024、0.025、0.026、0.028、0.03、0.04或0.05；a1为0.001、0.002、0.003、0.004、0.005、0.006、0.007、0.008、0.010、0.012、0.015、0.018、0.020、0.022、0.024、0.025、0.026、0.028、0.030、0.032、0.034、0.035、0.04、0.045、0.05、0.055、0.06、0.065、0.07、0.075、0.08、0.085、0.09或0.095；b1为0.001、0.002、0.003、0.004、0.005、0.006、0.007、0.008、0.010、0.012、0.015、0.018、0.020、0.022、0.024、0.025、0.026、0.028、0.030、0.032、0.034、0.035、0.04、0.045、0.05、0.055、0.06、0.065、0.07、0.075、0.08、0.085、0.09或0.095；b1/1-a1-b1为0.005、0.01、0.02、0.03、0.04、0.06、0.08、0.09、0.095或0.1。
式2中，y2为0.001、0.002、0.003、0.004、0.005、0.006、0.007、0.008、0.010、0.012、0.015、0.018、0.020、0.022、0.024、0.025、0.026、0.028、0.03、0.04或0.05；a2为.001、0.002、0.003、0.004、0.005、0.006、0.007、0.008、0.010、0.012、0.015、0.018、0.020、0.022、0.024、0.025、0.026、0.028、0.030、0.032、0.034、0.035、0.04、0.045、0.05、0.055、0.06、0.065、0.07、0.075、0.08、0.085、0.09或0.095；b2为0.001、0.002、0.003、0.004、0.005、0.006、0.007、0.008、0.010、0.012、0.015、0.018、0.02。a2/1-a2为0.005、0.01、0.02、0.03、0.04、0.06、0.08、0.09、0.095或0.1。
需要强调的是，上述对n1和n2的限定是指未经过任何充放电处理的正极活性材料中，与单位摩尔锂金属氧化物中锂的摩尔量相关的参数。能够理解，当将该正极活性材料应用于锂离子电池中进行任何充放电处理后，在不同的充放电机制以及充放电节点下，单位摩尔锂金属氧化物中锂的摩尔量是有差异的。
根据本申请提供的上述方案，相较于其他正极活性材料，将包括该锂金属氧化的正极活性材料应用于锂离子电池后，锂离子电池的比容量和循环性能得到显著提升，即使在高电压的工作条件下，锂离子电池的电性能也不会出现劣化。发明人基于此现象进行分析，认为可能是：一方面，M1的掺杂有助于对锂金属氧化物的结构进行支撑作用，使锂金属氧化物的结构稳定性在一定程度上得到提升，因此无论在常压或者高压的工作环境中，结构稳定的锂金属氧化物更有助于提升锂离子脱嵌的效率，促进锂离子电池循环性能和比容量的改善；另一方面，具有上述晶体特征的该锂金属氧化物具有更为完善的层状晶相结构，得以减少或抑制晶相内部混排现象的发生，进而能够使锂离子发生顺利的脱嵌，尤其在高压的充放电过程中展现出多个充放电小平台。
进一步地，式1中的M1选自Al、W和/或Te、B和/或P中的一种(即M1选自Al、W、Te、W和Te的共混、B、P、B和P的共混中的任意一种)；式2中的M1为K。具体地，当式1和式2中的M1选自不同掺杂元素时，对于锂金属氧化物相关电性能的改善程度具有一定差异。
详细而言，当式1中的M1含有Al、Te和/或W、P中的一种时，推测认为Al原子、Te原子和/或W原子、P原子能够替代锂金属氧化物中的Co原子，从而提升了锂金属氧化物的结构稳定性，使高压下的锂金属氧化物在不发生结构坍塌的情形下顺利完成锂离子的脱嵌，提高了电池的比容量以及循环性能；
当式1中的M1含有B原子时，B原子的嵌入能够替代锂金属氧化物中的Co原子，具有一定程度的助熔作用，有助于使锂金属氧化物为单晶形貌(即一次颗粒)，从而提高正极片的压实密度。
当式2中的M1选自K原子时，推测认为K原子半径大于Li原子和Na原子，在锂金属氧化物中K原子占位起支撑作用，有利于Li离子的脱嵌，从而利于循环性能和克容量的显著提升。此外，通过控制K的掺杂量，可以提高电池充放电过程中电化学动力学性能和倍率性能，并减小极化现象，对倍率性能和首效亦有正向促进作用。
除了上述锂金属氧化物对电池相关电性能的正向促进作用之外，当在锂金属氧化物的至少部分表面覆盖包覆层时，电池的表现会得到更进一步的改善。通过设置包覆层，正极活性材料为包括锂金属氧化物的内核、包覆层覆盖内核的核壳结构。该包覆层有助于减少或抑制锂金属氧化物和电解液的副反应，即使当电池在高压环境下工作时，正极活性材料和电解液之间依旧能够形成稳定的界面，通过避免正极活性离子中金属离子的过渡溶出以及避免缺液现象而使电池的循环性能得到改善。同时，副反应的抑制或减少也能够降低电池内部的产气量，从而也保证了电池的安全性能。
本申请不限定包覆层材料的选择，只要能够抑制副反应并保证锂离子的正常迁移即可。为了进一步提升锂离子电导率，包覆层可以选用含碳化合物、快离子导体等材料。
如前述，未经过任何充放电处理的锂金属氧化物中，n1和n2在0.6～0.8之间。当将包括正极活性材料的正极片和锂金属负极片组装为电池后进行充放电后，当电池的剩余电量SOC为0(即处于完全放电状态)且放电截止电压为3.0～3.6V时，锂金属氧化物的n1和n2在0.7～1.0之间。需要说明的是，该n1和n2的变化是指充放电循环圈数在10之内。具体地，满足前述锂金属氧化物在进行充放电应用后，其组成会发生变化，尤其是锂的摩尔量会明显提升。原因在于，具有前述晶型结构的锂金属氧化物中具有部分空位，因此当将其进行充放电处理(例如化成)时，其空位能够接受来自于锂负极的锂原子，进而使锂离子的摩尔量相较于充放电应用前得到提升。该特性有助于进一步提升电池的循环性能和比容量。
上述n1和n2的检测可以通过ICP执行。具体地，对放电后的电池进行拆解并取出正极片。利用碳酸二甲酯(DMC)浸泡1-3h或者DMC淋洗后，干燥房自然晾干后，置于马弗炉300～600℃焙烧2～5h，并用200目过筛后得到待检测粉末，随后通过ICP对待检测粉末中的金属元素进行检测，计算n1和n2。
本申请正极活性材料可以是单晶形貌或多晶形貌，具体形貌与其掺杂元素的选择以及比例相关。具体地，当为多晶形貌时，其为球状或类球状颗粒；当为单晶形貌时，其可以为须状、片状、或其他任意不规则的形状。
进一步地，本申请正极活性材料的中值粒径为12～20μm，例如为3μm、14μm、15μm、16μm、17μm、18μm、19μm或20μm。发明人发现，当正极活性材料的中值粒径满足上述要求时，一方面，其对应比表面积能够满足更多锂离子的脱嵌；另一方面，正极活性材料之间的团聚现象得到有效控制，从而在制浆过程中能够稳定分散在浆料中。
发明人发现，当锂金属氧化物满足特定元素M1的掺杂以及掺杂比例时，其充放电过程中的多个放电小平台均表现出较为优异的放电量。
在一种具体实施方式中，正极活性材料的第一阶段放电容量占比C1/C0≥9％，第二阶段放电容量占比C2/C0≥25％；其中，C0为包括所述正极活性材料的半电池在3.0～4.55V电压下进行放电处理时的放电容量；所述放电处理中，所述半电池由初始放电电压放电至4.4V时放电的容量定义为C1，所述半电池由3.8V放电至3.7V时放出的容量定义为C2。进一步地，C1/C0≥11％，第二阶段放电容量占比C2/C0≥28％。
需要解释的是，上述放电容量是在特殊的放电机制下进行的。具体地，包括正极活性材料的正极片和锂金属负极组成的半电池充电至SOC为100％后(对充电机制不做特殊限定)，在3.0～4.55V下以0.1C进行放电处理。其中自4.55V以0.1C放电至4.4V时其释放的电量为C1，继续放电当从3.8V放电至3.7V时该降压阶段释放的电量为C2，继续放电至3.0V(此时SOC为0)时其自放电初始释放的全部电量为C0。
很明显，在高压环境下的放电处理中，第一阶段放电电量占比和第二阶段放电容量占比皆表现优异。因此，包括本申请锂金属氧化物的正极活性材料耐压性强，从而能够通过对其进行升压处理而提升电池的比容量。
在一种实施方式中，锂金属氧化物中，002峰的峰强度为I1，所述131峰的峰强度为I2，且I1/I2≥4。此时锂金属氧化的内部晶型结构更加完善，因此有助于电池循环性能的改善。进一步地，I1/I2≥6。
本申请不限定上述锂金属氧化物的制备方法，在一种具体实施方式中，本申请的锂金属氧化物可以通过将式1a或2a所示的钠金属氧化物与锂化合物混合并进行离子处理的方法制备得到。Nax1Co1-a1-b1M1b1M2a1O2    式1a    Nax2Co1-a2M1b2M2a1O2    式2a
式1a中，0.68＜x1＜0.74，0<b1<0.1，0≤a<0.10，0<b1/1-a1<0.05；式2a中，0.68＜x2＜0.74，0＜b2＜0.02，0≤a2＜0.1。
上述离子交换处理是一种热处理过程，具体是指将钠金属氧化物和锂化合物混合后在80℃～300℃下进行不高于10h的热处理。在离子交换处理后，通过对离子交换后的体系进行洗涤、干燥，最终得到锂金属氧化物。其中，干燥的温度为80～180℃，时间至少为10h。对进行离子交换处理的设备和干燥设备不做限定，例如离子交换处理的设备可以是带有密闭功能和搅拌能力的密闭容器设备，如湿法包覆反应设备，共沉淀反应设备等；干燥设备可以是鼓风烘箱、真空干燥烘箱、回转窑、盘式干燥机、烤箱等。
上述锂化合物可以是本领域常用的锂源化合物，例如碳酸锂、氯化锂、溴化锂、碘化锂、硝酸锂、氢氧化锂、氟化锂中的至少一种。离子交换处理中，锂化合物和钠金属氧化物的质量比为不低于1:1，优选为(1-3)：1。
进一步地，当需要制备在锂金属氧化物外覆盖包覆层的正极活性材料时，在离子交换处理中除了包括钠金属氧化物和锂化合物的原料之外，还需要添加包覆层原料。
对于式1a和式2a所示的钠金属化合物，示例性，可以通过包括以下过程的方法制备得到：
将钴源、钠源、M1源以及M2源按照目标比例混合后进行煅烧处理，得到式1a和式2a所示的钠金属化合物。
具体地，煅烧处理的温度为700～900℃，时间为8～50h，煅烧处理可以在氧气或空气气氛下进行。煅烧处理的设备例如可以是马弗炉、隧道炉、辊道窑炉、管式炉等高温烧结设备。
上述各个源的混合可以通过高速混料设备、砂磨设备、球磨设备、犁刀混料设备、斜式混料设备等执行，需要注意的是，若使用砂磨设备、球磨设备且在球磨或砂磨过程中加入溶剂(水、乙醇或者其它溶剂介质)时，在混合处理结束后需要对混合后的体系进行干燥。一般的，混合时间不高于4h。
本申请不限定钴源、钠源、M1源以及M2源的具体选择。示例性地，钴源选自氢氧化钴、四氧化三钴、掺杂型四氧化三钴、氧化亚钴、羟基氧化钴、硝酸钴、硫酸钴等中的一种或多种；钠源选自碳酸钠、硝酸钠、氢氧化钠、碳酸氢钠、硫酸钠等中的一种或多种；M1源可以是任何含有M1的化合物，例如M1的氧化物，当M1为W时，M1源例如为钨酸和/或钨酸钠等；当M1为Te时，M1源例如为碲酸和/或碲酸钠等；当M1为Al时，M1源例如为硫酸铝、硝酸铝、氢氧化铝等中的一种或多种；当M1为B时，M1源例如为硼酸和/或硼酸钠等；当M1为P时，M1源例如为磷酸和/或磷酸钠等；当M1为K时，M1源例如为碳酸钾、硝酸钾、氢氧化钾、碳酸氢钾、硫酸钾等中的一种或多种；M2源例可以是任何含有M2的化合物，例如M2的氧化物，例如为碱式碳酸镁、氢氧化镁、氧化锆、氧化钇、氧化镧、氟化镧、氧化镍、氧化铌等中的一种或多种。
本申请第二方面提供一种正极片，该正极片包括上述第一方面所述的正极活性材料。
基于第一方面的正极活性材料的特性，本申请的正极片有助于改善锂离子电池的循环性能和比容量。
在一种具体实施方式中，本申请的正极片包括正极集流体和设置在正极集流体至少一表面的正极活性层，该正极活性层包括前述正极活性材料。
能够理解，除了正极活性材料之外，正极活性层还包括导电剂和粘结剂。示例性地，正极活性层按照质量百分含量包括70-99wt％的正极活性材料、0.5-15wt％的导电剂、0.5-15wt％的粘结剂，进一步地，包括80-98wt％的正极活性材料、1-10wt％的导电剂、1-10wt％的粘结剂。
导电剂和粘结剂的选择并无特殊，可以为本领域常规选择。例如，导电剂选自导电炭黑、乙炔黑、科琴黑、导电石墨、导电碳纤维、碳纳米管、单壁碳纳米管、多臂碳纳米管、碳纤维中的至少一种，粘结剂选自聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚丙烯酸锂(PAALi)中的至少一种。
进一步地，为了提升安全性能，还可以在正极活性层和集流体之间设置安全层。安全层的材料一般为非导电性的安全材料，例如含铁的化合物(如磷酸铁锂、磷酸锂等)、含铝的化合物(如陶瓷氧化铝)等。当然，安全层中也包括粘结剂，粘结剂和安全材料的比例可以根据具体需求而进一步确定。
本申请第三方面还提供一种锂离子电池，该离子电池包括上述正极片，因此在循环性能和比容量方面表现突出。
本申请不限定锂离子电池的具体结构，例如可以是方形壳电池、圆柱形电池等。
根据本申请，锂离子电池还包括负极片、隔膜和电解液。
示例性地，电解液为本领域已知的包括锂盐和溶剂的常规电解液，溶剂含有碳酸乙烯酯(简写为EC)、碳酸二乙酯(简写为DEC)、碳酸丙烯酯(简写为PC)、氟代碳酸乙烯酯(简写为FEC)。进一步地，还包括一种式T所示的添加剂，其在电解液中的质量百分含量为0.1～10％等。
示例性地，负极片可以为是含锂金属的负极片，例如可以是锂箔或者如图1所示的负极片。具体地，图1中的负极片包括层叠设置的负极集流体101、负极活性层20和锂材料层30。图1中的负极片为双面设置，当然也可以为仅在负极集流体单面设置负极活性层20和锂材料层30的负极片。锂材料层例如为锂箔，进一步地，锂材料层中金属锂的面密度为0.09mg/cm2～3.5mg/cm2；负极活性层包括负极活性材料、导电剂以及粘结剂。
在一种具体实施方式中，负极活性层按照质量百分含量包括70-99wt％的负极活性材料、0.5-15wt％的导电剂、0.5-15wt％的粘结剂，进一步地，包括80-98wt％的负极活性材料、1-10wt％的导电剂、1-10wt％的粘结剂。其中，负极活性材料选自人造石墨、天然石墨、硬炭、中间相碳微球、钛酸锂、硅碳、氧化亚硅中的一种或多种。
示例性地，隔膜为聚丙烯为基材的材料，或在此基础上单面或双面涂覆陶瓷的涂胶隔膜。
本申请的锂离子电池适用于高压体系，具体的，包括前述正极片的的锂离子扣式电池≥4.55V(相对锂)的条件下，正极片克容量发挥≥225mAh/g，且在≥4.50V(对应前述负极片)同时具有优异的循环性能。
因此，本申请在4.50V等更高电压具有良好的循环稳定性和较高的克容量的锂离子电池，可满足高端数码产品轻薄化的使用需求。
以下，通过具体实施例对本申请的正极活性材料进行介绍。
实施例1A
该实施例的正极活性材料按照以下方法制备：
(1)称取重量为36.56g的碳酸钠粉末、6.889g的碲酸粉末、282.32g的六水合硝酸钴粉末，将其放入高速混料设备中，设定混料程序，用300rpm混料3分钟后，用500rpm混料5分钟，再用1000rpm混料10分钟后取出混合料，确认混合料中没有白色的碳酸钠小白点存在后，认为混料均匀；
(2)取30g左右混合均匀的混合料，均匀装入陶瓷坩埚中，使用设备型号为VBF-1200X的井式马弗炉进行高温烧结，烧结的升温曲线为5℃/min，升温至750℃时进行恒温烧结10h，烧结后自然降温至常温后将样品取出，经电感耦合等离子光谱发生仪(ICP)检测得到钠金属氧化物Na0.69Co0.97Te0.03O2；
(3)取一个反应容器里先称取重量为10.49g的一水合氢氧化锂和质量为17.24g的硝酸锂颗粒，将两种锂的化合物分别加入反应容器中，称取质量为10g的步骤(2)合成的Na0.69Co0.97Te0.03O2，倒入反应容器中初步混合后，于280℃离子交换0.5h，得到粗品；
(4)粗品经过3次去离子水抽滤洗涤后，在90℃，干燥8h后得到样品1A#。
利用ICP对1A#进行检测分析，具体结果见表1A。
图2为本申请实施例1A中样品1A#的XRD图。从图2可知，本实施例中制备得到的锂金属氧化物具有002峰以及131峰，且其为立方晶系的Cmca空间群，具有T2结构。
实施例2A-9A
实施例2A-9A的制备方法与实施例1A的制备方法基本相同，不同处仅在于步骤(1)中选取不同的M1(W源或Te源)、M2源，以及各个金属源之间的质量比，具体选择见表1A，最终得到样品2A#-9A#，其ICP的检测分析结果见表1A。
实施例10A
实施例10A的制备方法与实施例1A的制备方法基本相同，不同处仅在于步骤(1)为：称取重量为36.56g的碳酸钠粉末、称取4.593g碲酸粉末、以及称取79.30g已经进行铝掺杂四氧化三钴的化合物(Co0.95Al0.03)3O4，放入高速混料设备中，设定混料程序，用300rpm混料3分钟后，用500rpm混料5分钟，再用1000rpm混料10分钟后取出混合料，确认混合料中没有白色的碳酸钠小白点存在后，认为混料均匀；
最终步骤2)得到的钠金属氧化物为Na0.69Co0.95Te0.02Al0.03O2且10A#样品为Li0.71Na0.02Co0.95Te0.02Al0.03O2。
实施例11A
实施例11A的制备方法与实施例10A的制备方法基本相同，不同处仅在于步骤(3)为：取一个反应容器里先称取重量为10.49g的一水合氢氧化锂和质量为17.24g的硝酸锂颗粒，将两种锂的化合物分别加入反应容器中，称取质量为10g的步骤(2)合成的Na0.69Co0.95Te0.02Al0.03O2，倒入反应容器中初步混合后，于280℃离子交换1h，得到粗品；经过步骤(4)的处理后，得到样品11A#Li0.71Na0.02Co0.95Te0.02Al0.03O2。
实施例12A
实施例12A的制备方法与实施例10A的制备方法基本相同，不同处仅在于步骤(3)为：取一个反应容器里先称取重量为10.49g的一水合氢氧化锂和质量为9.24g的碳酸锂颗粒，将两种锂的化合物分别加入反应容器中，称取质量为10g的步骤(2)合成的Na0.69Co0.95Te0.02Al0.03O2，倒入反应容器中初步混合后，于280℃离子交换0.5h，得到粗品；经过步骤(4)的处理后，得到样品12A#Li0.71Na0.0.02Co0.95Te0.02Al0.03O2。
实施例13A
实施例13A的制备方法与实施例10A的制备方法基本相同，不同处仅在于步骤(3)为：取一个反应容器里先称取重量为10.49g的一水合氢氧化锂和质量为10.59g的氯化锂颗粒，将两种锂的化合物分别加入反应容器中，称取质量为10g的步骤(2)合成的Na0.69Co0.95Te0.02Al0.03O2，倒入反应容器中初步混合后，于280℃离子交换0.5h，得到粗品；经过步骤(4)的处理后，得到样品13A#Li0.71Na0.0.02Co0.95Te0.02Al0.03O2。
表1A
实施例1B
该实施例的正极活性材料按照以下方法制备：
(1)称取重量为36.56g的碳酸钠粉末、1.53g的纳米氧化铝粉末、276.50g的六水合硝酸钴粉末和0.806g的纳米氧化镁粉末，将其放入高速混料设备中，设定混料程序，用300rpm混料3分钟后，用500rpm混料5分钟，再用1000rpm混料10分钟后取出混合料，确认混合料中没有白色的碳酸钠小白点存在后，认为混料均匀；
(2)取30g左右混合均匀的混合料，均匀装入陶瓷坩埚中，使用设备型号为VBF-1200X的井式马弗炉进行高温烧结，烧结的升温曲线为5℃/min，升温至750℃时进行恒温烧结10h，烧结后自然降温至常温后将样品取出，经电感耦合等离子光谱发生仪(ICP)检测得到钠金属氧化物Na0.69Co0.95Al0.03Mg0.02O2；
(3)取一个反应容器里先称取重量为10.49g的一水合氢氧化锂和质量为17.24g的硝酸锂颗粒，将两种锂的化合物分别加入反应容器中，称取质量为10g的步骤(2)合成的Na0.69Co0.95Al0.03Mg0.02O2，倒入反应容器中初步混合后，于280℃离子交换0.5h，得到的样品；
(4)粗品经过3次去离子水抽滤洗涤后，在90℃，干燥8h后得到样品1B#。
利用ICP对1B#进行检测分析，具体结果见表1B。
实施例2B-9B
实施例2B-9B的制备方法与实施例1B的制备方法基本相同，不同处仅在于步骤(1)中选取不同的M2源，以及各个金属源之间的质量比，具体选择见表1B，最终得到样品2B#-9B#，其ICP的检测分析结果见表1B。
实施例10B
实施例10B的制备方法与实施例1B的制备方法基本相同，不同处仅在于步骤(1)为：称取重量为36.56g的碳酸钠粉末、称取重量为79.30g已经进行铝掺杂四氧化三钴的化合物(Co0.95Al0.03)3O4，放入高速混料设备中，设定混料程序，用300rpm混料3分钟后，用500rpm混料5分钟，再用1000rpm混料10分钟后取出混合料，确认混合料中没有白色的碳酸钠小白点存在后，认为混料均匀；
最终步骤2)得到的钠金属氧化物为Na0.69Co0.97Al0.03O2且10B#样品为Li0.71Na0.02Co0.97Al0.03O2。
实施例11B
实施例11B的制备方法与实施例10B的制备方法基本相同，不同处仅在于步骤(3)中的离子交换时间为1h。得到的样品11B#为Li0.71Na0.02Co0.97Al0.03O2。
实施例12B
实施例12B的制备方法与实施例10B的制备方法基本相同，不同处仅在于步骤(3)中利用9.24g的碳酸锂颗粒替换17.24g的硝酸锂颗粒。得到的样品12B#为Li0.71Na0.02Co0.97Al0.03O2。
实施例13B
实施例13B的制备方法与实施例10B的制备方法基本相同，不同处仅在于步骤(3)中利用10.59g的氯化锂颗粒替换17.24g的硝酸锂颗粒。得到的样品13B#为Li0.71Na0.02Co0.97Al0.03O2。
表1B

实施例1C
该实施例的正极活性材料按照以下方法制备：
(1)称取重量为36.56g的碳酸钠粉末、1.854g的硼酸粉末、282.32g的六水合硝酸钴粉末，将其放入高速混料设备中，设定混料程序，用300rpm混料3分钟后，用500rpm混料5分钟，再用1000rpm混料10分钟后取出混合料，确认混合料中没有白色的碳酸钠小白点存在后，认为混料均匀；
(2)取30g左右混合均匀的混合料，均匀装入陶瓷坩埚中，使用设备型号为VBF-1200X的井式马弗炉进行高温烧结，烧结的升温曲线为5℃/min，升温至750℃时进行恒温烧结10h，烧结后自然降温至常温后将样品取出，经电感耦合等离子光谱发生仪(ICP)检测得到钠金属氧化物Na0.69Co0.97B0.03O2；
(3)取一个反应容器里先称取重量为10.49g的一水合氢氧化锂和质量为17.24g的硝酸锂颗粒，将两种锂的化合物分别加入反应容器中，称取质量为10g的步骤(2)合成的Na0.69Co0.97B0.03O2，倒入反应容器中初步混合后，于280℃离子交换0.5h，得到的粗品；
(4)粗品经过3次去离子水抽滤洗涤后，在90℃，干燥8h后得到样品1C#。
利用ICP对1C#进行检测分析，具体结果见表1C。
图3为本申请实施例1C中的样品1C#的SEM图。
实施例2C-9C
实施例2C-9C的制备方法与实施例1C的制备方法基本相同，不同处仅在于步骤(1)中选取不同的M1(B源或P源)、M2源，以及各个金属源之间的质量比，具体选择见表1C，最终得到样品2C#-9C#，其ICP检测分析结果见表1C。图4为本申请实施例3C中的样品3C#的SEM图。
实施例10C
实施例10C的制备方法与实施例1C的制备方法基本相同，不同处仅在于步骤(1)为：称取重量为36.56g的碳酸钠粉末、称取1.236g硼酸粉末、以及称取79.30g已经进行铝掺杂四氧化三钴的化合物(Co0.95Al0.03)3O4，放入高速混料设备中，设定混料程序，用300rpm混料3分钟后，用500rpm混料5分钟，再用1000rpm混料10分钟后取出混合料，确认混合料中没有白色的碳酸钠小白点存在后，认为混料均匀；
最终步骤2)得到的钠金属氧化物为Na0.69Co0.95B0.02Al0.03O2且10C#样品为Li0.71Na0.02Co0.95B0.02Al0.03O2。
实施例11C
实施例11C的制备方法与实施例10C的制备方法基本相同，不同处仅在于步骤(3)中的离子交换时间为1h。得到的样品11C#为Li0.71Na0.02Co0.95B0.02Al0.03O2。
实施例12C
实施例12C的制备方法与实施例10C的制备方法基本相同，不同处仅在于步骤(3)中利用9.24g的碳酸锂颗粒替换17.24g的硝酸锂颗粒。得到的样品12C#为Li0.71Na0.02Co0.95B0.02Al0.03O2。
实施例13C
实施例13C的制备方法与实施例10C的制备方法基本相同，不同处仅在于步骤(3)中利用10.59g的氯化锂颗粒替换17.24g的硝酸锂颗粒。得到的样品13C#为Li0.71Na0.02Co0.95B0.02Al0.03O2。
表1C
实施例1D
该实施例的正极活性材料按照以下方法制备：
(1)称取重量为36.56g的碳酸钠粉末、0.21g的碳酸钾粉末、282.31g的六水合硝酸钴粉末和1.21g的纳米氧化镁粉末，将其放入高速混料设备中，设定混料程序，用300rpm混料3分钟后，用500rpm混料5分钟，再用1000rpm混料10分钟后取出混合料，确认混合料中没有白色的碳酸钠小白点存在后，认为混料均匀；
(2)取30g左右混合均匀的混合料，均匀装入陶瓷坩埚中，使用设备型号为VBF-1200X的井式马弗炉进行高温烧结，烧结的升温曲线为5℃/min，升温至750℃时进行恒温烧结10h，烧结后自然降温至常温后将样品取出，经电感耦合等离子光谱发生仪(ICP)检测得到钠金属氧化物Na0.69K0.003Co0.97Mg0.03O2；
(3)取一个反应容器里先称取重量为10.49g的一水合氢氧化锂和质量为17.24g的硝酸锂颗粒，将两种锂的化合物分别加入反应容器中，称取质量为10g的步骤(2)合成的Na0.69K0.003Co0.97Mg0.03O2，倒入反应容器中初步混合后，于280℃离子交换0.5h，得到的样品；
(4)粗品经过3次去离子水抽滤洗涤后，在90℃，干燥8h后得到样品1D#。
利用ICP对1D#进行检测分析，具体结果见表1D。
实施例2D-9D
实施例2D-9D的制备方法与实施例1D的制备方法基本相同，不同处仅在于步骤(1)中选取不同的M2源，以及各个金属源之间的质量比，具体选择见表1D，最终得到样品2D#-9D#，其ICP的检测分析结果见表1D。
实施例10D
实施例10D的制备方法与实施例1D的制备方法基本相同，不同处仅在于步骤(3)中的离子交换时间为1h。得到的样品10D#为Li0.71Na0.02K0.003Co0.97Mg0.03O2。
实施例11D
实施例11D的制备方法与实施例1D的制备方法基本相同，不同处仅在于步骤(3)中的离子交换温度为260℃。得到的样品10D#为Li0.71Na0.02K0.003Co0.97Mg0.03O2。
实施例12D
实施例12D的制备方法与实施例1D的制备方法基本相同，不同处仅在于步骤(3)中利用9.24g的碳酸锂颗粒替换17.24g的硝酸锂颗粒。得到的样品12D#为Li0.71Na0.02K0.003Co0.97Mg0.03O2。
实施例13D
实施例13D的制备方法与实施例1D的制备方法基本相同，不同处仅在于步骤(3)中利用10.59g的氯化锂颗粒替换17.24g的硝酸锂颗粒。得到的样品13D#为Li0.71Na0.02K0.003Co0.97Mg0.03O2。
表1D


表1A-1D中未填写的部分代表该实施例的原料中不包括该化合物
对比例1
本对比例的正极活性材料的化学组成为Li1.0026CoO2；
制备方法包括如下步骤：
(1)按摩尔比例Li:Co＝100.26:100称取碳酸锂和市面上购买的常规的非掺杂的球形Co3O4颗粒，将两种物质使用与实验例相同的搅拌设备，将其放入高速混料设备中，设定混料程序，用300rpm混料3分钟后，用500rpm混料5分钟，再用1000rpm混料10分钟后取出混合料，确认混合料中没有白色的碳酸锂小白点存在后，认为混料均匀；
(2)取30g左右混合均匀的混合料，均匀装入陶瓷坩埚中，使用设备型号为VBF-1200X的井式马弗炉进行高温烧结，烧结的升温曲线为5℃/min，升温至1050℃时进行恒温烧结10h，烧结后自然降温至常温后将样品取出，得到烧结后的粗品；
(3)粗品进行粉碎研磨处理后，将粉末置于马弗炉中在950℃，烧结时间为8h，然后对烧结产物进行粉碎处理，得到D50为15.2μm的未有任何掺杂包覆的Li1.0026CoO2。
对比例2
本对比例的正极活性材料为常规高电压掺杂包覆钴酸锂正极材料，其化学组成为Li1.0027Co0.97Al0.03O2。
制备方法包括如下步骤：
(1)按摩尔比例Li:Co＝100.27:97称取碳酸锂和市面上购买的常规的带有掺杂Al的球形Co3O4颗粒，该Co3O4颗粒的化学计量比为Co:Al＝97:3.0将两种物质使用与实验例相同的搅拌设备，将其放入高速混料设备中，设定混料程序，用300rpm混料3分钟后，用500rpm混料5分钟，再用1000rpm混料10分钟后取出混合料，确认混合料中没有白色的碳酸锂小白点存在后，认为混料均匀；
(2)取30g左右混合均匀的混合料，均匀装入陶瓷坩埚中，使用设备型号为VBF-1200X的井式马弗炉进行高温烧结，烧结的升温曲线为5℃/min，升温至1030℃时进行恒温烧结10h，烧结后自然降温至常温后将样品取出，得到Li1.0027Co0.97Al0.03O2。
对比例3
对比例3的制备方法与实施例1A的制备方法基本相同，不同处仅在于步骤(1)为：称取重量为36.56g的碳酸钠粉末和291.05g的六水合硝酸钴粉末，不添加任何添加剂，将其放入高速混料设备中，设定混料程序，用300rpm混料3分钟后，用500rpm混料5分钟，再用1000rpm混料10分钟后取出混合料，确认混合料中没有白色的碳酸钠小白点存在后，认为混料均匀；
经过步骤(2)-(4)的处理后，得到T2结构对比例3的产品，化学式为Li0.71Na0.02CoO2。
对比例4
本对比例的正极活性材料为常规高电压掺杂包覆钴酸锂正极材料，其化学组成为Li1.0027Co0.947K0.003Mg0.03La0.02O2。
制备方法包括如下步骤：
(1)按摩尔比例Li:Co：K＝100.27:94.7：0.3称取碳酸锂和市面上购买的常规的带有掺杂Mg和La的球形Co3O4颗粒以及氧化镁颗粒，该Co3O4颗粒的化学计量比为Co:Mg:La＝94.7:3.0:2，将三种物质使用与实验例相同的搅拌设备，将其放入高速混料设备中，设定混料程序，用300rpm混料3分钟后，用500rpm混料5分钟，再用1000rpm混料10分钟后取出混合料，确认混合料中没有白色的碳酸锂小白点存在后，认为混料均匀；
(2)取30g左右混合均匀的混合料，均匀装入陶瓷坩埚中，使用设备型号为VBF-1200X的井式马弗炉进行高温烧结，烧结的升温曲线为5℃/min，升温至1030℃时进行恒温烧结10h，烧结后自然降温至常温后将样品取出，得到对比例4的产品Li1.0027Co0.947K0.003Mg0.03La0.02O2。
试验例1
对所有实施例和对比例的产品进行XRD衍射，结果见表2A～2D。
试验例2
将所有实施例和对比例中的产品制作为正极片后，与负极片、电解液以及隔膜按照以下方法组装得到锂离子电池。方法包括：
1)将实施例和对比例中的正极活性材料分别与导电碳黑、PVDF按照96％:2％:2％的重量比混合，通过分散得到正极浆料。将该浆料涂布在铝箔集流体上，辊压制备得到正极片；
2)将人造石墨、苯乙烯二烯橡胶(SBR)、及羧甲基纤维素钠、导电碳黑以94％:3％:2％:1％的重量比混合，将混合物分散于水中通过双行星混合后得到负极浆液。将该浆液涂覆于铜集流体上，接着进行辊压及干燥；
随后通过轧制方式在负极活性层表面叠加锂材料层，锂材料层为锂箔，金属锂的面密度为1.0mg/cm2，最终得到含有锂金属的负极片。
3)然后将正极片、负极片和隔膜组装成锂离子电池，并注入非水电解液。
其中，电解液为本领域已知的常规电解液，按碳酸乙烯酯(简写为EC)：碳酸二乙酯(简写为DEC)：碳酸丙烯酯(简写为PC)＝2：5：3的质量比混合后，加入占电解液总质量的5％的氟代碳酸乙烯酯(简写为FEC)、加入占电解液总质量的13％的六氟磷酸锂(简写为LiPF6)，以及式T所示的添加剂，添加剂含量占电解液总含量的2％。
对得到的各个锂离子电池的容量保持率进行测试，具体测试方法为：在25℃下，以1C的充电倍率恒流充电至4.50V，再以0.05C的充电倍率恒压充电至4.50V，然后以1C的放电倍率放电至3.0V，反复500次这种充放电循环，测定第一次循环时的放电容量和第500次循环时的放电容量，按照下式求出500圈循环后的容量保持率，结果见表2A～2D。
容量保持率Q＝(第500次循环时的放电容量)/(第一次循环时的放电容量)*100％
图5为本申请实施例1D中的样品1D#和对比例3中的样品的循环性能比较曲线。
试验例3
将所有实施例和对比例中的产品制作为正极片后，与负极片、电解液以及隔膜按照以下方法组装得到扣式电池。方法包括：
将实施例和对比例中的正极活性材料分别与导电碳黑(SP)、PVDF按照80％:10％:10％的重量比混合，通过分散得到正极浆料。将该浆料涂布在铝箔集流体上，辊压制备得到正极片，然后将正极片用膜具冲型直径为12mm的小圆片，烘干称重处理后，在Ar保护气氛下的手套箱中，使用2025的扣式电池壳，用Li金属圆片做负极，常规高电压钴酸锂电解液一起组装成扣式电池。
对得到的各个扣式电池在常规环境下静置4h后，进行首次充放电容量测试，测试条件为：0.1C充电至4.55V，恒压充电至0.025C截止后，静置3min后，0.1C放电至3.0V。在放电过程中，分别记录记录4.4～4.55V的放电电量C1、3.7～3.8V的放电电量C2、首次放电全电量C0、首次充电容量，并计算首次效率、第一阶段放电容量占比C1/C0以及第二阶段放电容量占比C2/C0。结果见表2A～2D。
试验例4
将所有实施例和对比例中的产品按照试验例2中的方法组装得到锂离子电池后进行化成处理，随后将锂离子电池按标定容量的1/10的电流进行放电至3.0V后，对其电压进行测试发现，其电压为3.0～3.6V，然后对锂离子电池进行拆卸，取出正极极片，使用碳酸二甲酯(DMC)浸泡3h或者DMC淋洗后，干燥房自然晾干后，置于马弗炉300℃焙烧3H后，在200目过筛后得到样品粉末，使用ICP测试样品粉末中的各元素的含量，根据Li、Na等元素检测值计算n。结果见表2A～2D。
表2A
表2B
表2C
表2D表2A-2D中“/”表示无该参数
根据表2A～2D可知：
1、根据实施例1(ABCD)～9(ABCD)可知，虽然不同M1和M2源的选择以及比例均对合成的锂金属氧化物的组成和晶型结构具有一定的影响，但是相对于对比例而言，实施例锂离子电池在高压(4.5V、4.55V及以上电压体系)下的克容量和循环性能都具有突出的表现；
需要强调的是，虽然对比例3的产品具有和实施例基本相同的晶型结构，但是其由于没有特定元素的掺杂，因此在克容量和循环性能方面的表现与实施例仍然有一定的差距；
2、根据实施例1(ABCD)和实施例10～13(ABCD)的对照可知，不同的制备参数如反应温度、反应时间、原料选择差异等，对锂金属氧化物的组成以及晶型结构均有一定的影响，并最终影响锂离子电池的相关表现；
3、对比例3虽然具有002峰和131峰，但是由于其没有M1掺杂元素，其002峰和131峰的比值强度明显偏低些，因此在循环性能方面的表现不甚理想。

Claims (18)

  1. 一种正极活性材料，所述正极活性材料包括式1或式2所示的锂金属氧化物；
    在X射线衍射图谱中，所述锂金属氧化物为立方晶系的Cmca空间群，且具有2θ为17.9°～18.1°的002峰，以及2θ为67.0°～67.5°的131峰；
    Lin1-y1Nay1Co1-a1-b1M1b1M2a1O2  式1
    Lin2-y2-b2Nay2Co1-a2M1b2M2a2O2  式2
    式1中，0.6≤n1≤0.8，0＜y1≤0.05，0≤a1≤0.1，0＜b1≤0.1，0<b1/1-a1-b1<0.1；
    式2中，0.6≤n2≤0.8，0＜y2≤0.05，0≤a2≤0.1，0＜b2≤0.02，
    其中，M1选自Te、W、Al、B、P以及K中的至少一种；M2为掺杂元素。
  2. 根据权利要求1所述的正极活性材料，其中，式1中，M1选自Al、W和/或Te、B和/或P中的一种；
    式2中，M1为K。
  3. 根据权利要求1或2所述的正极活性材料，其中，所述正极活性材料由包括所述锂金属氧化物的内核和覆盖内核至少部分表面的包覆层构成。
  4. 根据权利要求1或2所述的正极活性材料，其中，所述正极活性材料在截止电压为3.0～3.6V且SOC为零时，0.7≤n1，n2≤1.0。
  5. 根据权利要求1或2所述的正极活性材料，其中，所述正极活性材料的中值粒径为12μm～20μm。
  6. 根据权利要求1-5任一项所述的正极活性材料，其中，
    所述正极活性材料的第一阶段放电容量占比C1/C0≥9％，第二阶段放电容量占比C2/C0≥25％；
    其中，C0为包括所述正极活性材料的半电池在3.0～4.55V电压下进行放电处理时的放电容量；所述放电处理中，所述半电池由初始放电电压放电至4.4V时放出的容量定义为C1，所述半电池由3.8V放电至3.7V时放出的容量定义为C2。
  7. 根据权利要求1所述的正极活性材料，其中，所述002峰的峰强度为I1，所述131峰的峰强度为I2，且I1/I2≥4。
  8. 一种正极片，其中，所述正极片包括权利要求1-7任一项所述的正极活性材料。
  9. 根据权利要求8所述的正极片，其中，所述正极片包括正极集流体和设置在正极集流体至少一表面的正极活性层，所述正极活性层按照质量百分含量70-99wt％正极活性材料、0.5-15wt％导电剂、0.5-15wt％粘结剂。
  10. 根据权利要求9所述的正极片，其中，述正极活性层按照质量百分含量包括80-98wt％正极活性材料、1-10wt％导电剂、1-10wt％的粘结剂。
  11. 一种锂离子电池，其中，所述锂离子电池包括权利要求8-10任一项所述的正极片。
  12. 根据权利要求11所述的锂离子电池，其中，所述锂离子电池中的负极片为含锂负极片。
  13. 根据权利要求12所述的锂离子电池，其中，所述负极片为锂箔。
  14. 根据权利要求12所述的锂离子电池，其中，所述负极片包括层叠设置的负极集流体以及设置在所述负极集流体至少一个表面的负极活性层和锂材料层，且所述负极活性层靠近所述负极集流体。
  15. 根据权利要求14所述的锂离子电池，其中，所述锂材料层为锂箔。
  16. 根据权利要求14或15所述的锂离子电池，其中，所述锂材料层中金属锂的面密度为0.09mg/cm2～3.5mg/cm2。
  17. 根据权利要求14所述的锂离子电池，其中，所述负极活性层按照质量百分含量包括70-99wt％负极活性材料、0.5-15wt％导电剂、0.5-15wt％粘结剂。
  18. 根据权利要求17所述的锂离子电池，其中，所述负极活性层按照质量百分含量包括80-98wt％的负极活性材料、1-10wt％的导电剂、1-10wt％的粘结剂。
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