Lithium cobalt oxide positive electrode material and preparation method and application thereof

Abstract

The invention belongs to the field of batteries, and particularly discloses a lithium cobalt oxide positive electrode material and a preparation method and application thereof, the positive electrode material comprises a doped lithium cobalt oxide matrix, an inner coating layer and an outer coating layer; an inner coating layer is arranged on the surface of the doped lithium cobalt oxide substrate, and an outer coating layer is arranged on the surface of the inner coating layer; the doped lithium cobalt oxide matrix is LiCo < x > M < y > O < 2 >, and the inner coating layer contains LiF and AlF < 3 >; and Li3PO4 is contained in the outer coating layer. According to the invention, the lithium cobalt oxide matrix is doped by adopting the doping element, and meanwhile, the specific inner coating layer and the specific outer coating layer are arranged on the surface of the doped lithium cobalt oxide matrix, so that structural collapse and capacity attenuation of the positive electrode material in the charge-discharge process under high voltage can be avoided; and thus, the positive electrode material can have relatively high specific capacity and excellent cycling stability under high voltage.

Description

Technical Field

[0001] This invention belongs to the field of batteries, specifically relating to a lithium cobalt oxide cathode material, its preparation method, and its application. Background Technology

[0002] Lithium cobalt oxide is a commonly used cathode material. When used at high voltages above 4.6V, the increased lithium-ion extraction leads to lattice oxygen participating in charge compensation, causing oxygen vacancy aggregation and Co... 4+ Dissolution leads to structural collapse and capacity decay. For example, research from Peking University found that commercial lithium cobalt oxide at 4.6V exhibited only 74.6% capacity retention during cycling at 45℃, with a significant increase in surface cracks. Under high voltage, the electrolyte is prone to oxidative decomposition, generating corrosive substances such as HF, which damage the surface of the cathode material and exacerbate the increase in interfacial impedance. These problems severely restrict the use of lithium cobalt oxide at high voltages of 4.6V and above.

[0003] Related technologies mainly employ single-element coating or bulk doping (a deep doping method that introduces impurity elements into the lithium cobalt oxide material to alter its overall properties) to improve the problems encountered by lithium cobalt oxide under high pressure. However, single-element coating suffers from problems such as easy formation of byproducts, easy peeling of the coating layer, and limited performance improvement. Bulk doping, on the other hand, suffers from poor elemental uniformity. These problems all affect the structural stability and capacity performance of lithium cobalt oxide. Furthermore, related technologies often use single-element doping in bulk doping, which cannot achieve gradient buffering of stress, thus limiting the improvement of lithium cobalt oxide performance and preventing stable long-term cycling under high pressure. Summary of the Invention

[0004] In order to overcome at least one of the technical problems existing in the prior art, one of the objectives of the present invention is to provide a positive electrode material.

[0005] The second objective of this invention is to provide a method for preparing a cathode material.

[0006] The third objective of this invention is to provide a product.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A first aspect of the present invention provides a cathode material comprising a doped lithium cobalt oxide substrate, an inner coating layer, and an outer coating layer; wherein the inner coating layer is disposed on the surface of the doped lithium cobalt oxide substrate, and the outer coating layer is disposed on the surface of the inner coating layer; The doped lithium cobalt oxide matrix is ​​LiCo. x M y O2, 0.95≤x≤0.99, 0.01≤y≤0.05, x+y=1; M is selected from at least one of Al, Mg, Ti, Zr, La, Y, Se, W, P, Na, Ca, Se, Sc, V, Cr, Nd, Zn, Ni, Mn, and B; The inner coating layer contains LiF and AlF3; The outer coating layer contains Li3PO4.

[0008] In some descriptions of the present invention, the content of M gradually decreases from the surface of the doped lithium cobalt oxide substrate to the interior of the doped lithium cobalt oxide substrate.

[0009] In some embodiments of the present invention, the atomic percentage of M on the surface of the doped lithium cobalt oxide substrate is 0.8 to 4.0 at, based on the total number of Co atoms in LiCoO2.

[0010] In some embodiments of the present invention, the atomic percentage of M inside the doped lithium cobalt oxide matrix is ​​0.2 to 1.0 at, based on the total number of Co atoms in LiCoO2.

[0011] This invention introduces a dopant element M into a lithium cobalt oxide (LiCoO2) matrix. M atoms occupy cobalt lattice sites in the lithium cobalt oxide matrix. Therefore, the atomic percentage of M on the surface and inside the doped lithium cobalt oxide matrix is ​​calculated based on the total number of Co atoms in the undoped lithium cobalt oxide (LiCoO2) matrix. The doped lithium cobalt oxide matrix surface refers to the region with a distance ≤50nm from the outer surface of the doped lithium cobalt oxide matrix; the doped lithium cobalt oxide matrix interior refers to the region with a distance >50nm from the outer surface of the doped lithium cobalt oxide matrix.

[0012] In some embodiments of the present invention, the molar ratio of LiF to AlF3 is 1:(1~3).

[0013] In some embodiments of the present invention, the thickness of the outer coating layer is 5-10 nm; and / or, the thickness of the inner coating layer is 2-5 nm.

[0014] In some embodiments of the present invention, M is selected from Al, Mg, Ti and Zr; the molar ratio of Al to Zr is (1~25):1; the molar ratio of Mg to Zr is (0.5~15):1; and the molar ratio of Ti to Zr is (0.4~8):1.

[0015] The second aspect of the present invention provides a method for preparing the cathode material described in the first aspect of the present invention, comprising the following steps: The raw materials used to prepare the cathode material are mixed and ground to obtain precursor powder; The precursor powder was plasma activated in an oxygen-containing atmosphere to obtain the activated precursor. The activated precursor was first calcined in an oxygen-containing atmosphere, and then calcined a second time in AlF3 vapor to obtain the cathode material.

[0016] In some embodiments of the present invention, the radio frequency used in the plasma activation is 10~15 MHz.

[0017] In some embodiments of the present invention, the gas pressure during plasma activation is 30~60 Pa.

[0018] In some embodiments of the present invention, the plasma power in the plasma activation is 200~800W.

[0019] In some embodiments of the present invention, the plasma activation time is 10-30 min.

[0020] In some embodiments of the present invention, the oxygen-containing atmosphere in the plasma activation is a mixture of oxygen and at least one selected from nitrogen and inert gases.

[0021] In some embodiments of the present invention, the temperature of the first calcination is 800-1050°C.

[0022] In some embodiments of the present invention, the temperature of the second calcination is 450-550°C.

[0023] In some embodiments of the present invention, the partial pressure of the AlF3 vapor is 0.1 to 0.3 atm.

[0024] In some embodiments of the present invention, during the first calcination and / or the second calcination, the temperature of the surface of the doped lithium cobalt oxide substrate is 30-80°C higher than the temperature inside the doped lithium cobalt oxide substrate.

[0025] A third aspect of the present invention provides a product comprising the positive electrode material described in the first aspect of the present invention; the product comprising a battery or an electrical device containing a battery.

[0026] The beneficial effects of this invention are as follows: By doping the lithium cobalt oxide matrix with doping elements and simultaneously setting specific inner and outer coating layers on the surface of the doped lithium cobalt oxide matrix, this invention can avoid structural collapse and capacity decay of the cathode material during high-voltage charge and discharge, thereby enabling the cathode material to have high specific capacity and excellent cycle stability under high voltage. Specifically, the Li3PO4 in the outer coating layer can reduce oxygen loss and improve the structural stability of the cathode material, while the LiF and AlF3 in the inner coating layer can, on the one hand, block the generation of HF and enhance interface stability; on the other hand, they can provide lithium-ion superconducting channels during charge and discharge and synergistically suppress high-voltage side reactions.

[0027] When the positive electrode material of this invention is applied to a battery, the battery can exhibit the following performance characteristics: an initial discharge capacity of 235~247 mAh / g, a capacity retention rate of 83.1~89.3% after 1000 cycles at 4.6V, an oxygen vacancy concentration of 5.3~7.2%, and an interfacial impedance of 4.7~10.5Ω.cm 2 The Co leaching amount is 0.8~2.5 μg / cm³. 2 .

[0028] The preparation method of this invention achieves oxygen vacancy repair by plasma activation of precursor powder, suppressing the oxygen vacancy concentration to ≤5%. At the same time, gradient calcination at the first and second calcination temperatures makes the inner and outer coating layers more dense. This allows for precise control of the coating thickness and composition, reduces production costs, increases production efficiency by more than 40%, is compatible with recycled raw materials, and is suitable for existing lithium-ion battery production lines, making it suitable for large-scale application. Attached Figure Description

[0029] Figure 1 This is an EDS line scan of the lithium cobalt oxide cathode material prepared in Example 1.

[0030] Figure 2 The images show the XRD patterns of the lithium cobalt oxide cathode materials prepared in Example 1 and Comparative Example 1.

[0031] Figure 3 This is a scanning electron microscope image of the lithium cobalt oxide cathode material prepared in Example 1, magnified 1000 times. Detailed Implementation

[0032] The specific implementation of the present invention will be further described in detail below with reference to the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described in detail below are those that can be implemented or understood by those skilled in the art by referring to the prior art. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0033] In some embodiments of the present invention, the present invention provides a cathode material, including a doped lithium cobalt oxide substrate, an inner coating layer and an outer coating layer; the inner coating layer is disposed on the surface of the doped lithium cobalt oxide substrate, and the outer coating layer is disposed on the surface of the inner coating layer; The doped lithium cobalt oxide matrix is ​​LiCo x M y O2, 0.95≤x≤0.99, 0.01≤y≤0.05, x+y=1; M is selected from at least one of Al, Mg, Ti, Zr, La, Y, Se, W, P, Na, Ca, Se, Sc, V, Cr, Nd, Zn, Ni, Mn, and B; The inner coating layer contains LiF and AlF3; The outer coating contains Li3PO4.

[0034] This invention involves forming an inner coating layer and an outer coating layer on the surface of a doped lithium cobalt oxide substrate. The outer coating layer is formed by applying PO4. 3- Strong covalent bonds anchor the oxygen lattice on the surface of the lithium cobalt oxide matrix, suppressing the oxygen vacancy concentration to ≤5% and blocking the O2 release pathway under a high voltage of 4.60. The LiF in the inner coating layer provides a lithium-ion superconducting channel, and AlF3 reacts with HF in the electrolyte to form an AlF3·HF complex, which significantly reduces the amount of Co dissolved from the cathode material.

[0035] In some embodiments of the present invention, x is selected from any value or a range of values ​​formed by any two of the following: 0.95, 0.952, 0.954, 0.956, 0.958, 0.96, 0.962, 0.964, 0.966, 0.968, 0.97, 0.972, 0.974, 0.976, 0.978, 0.98, 0.982, 0.984, 0.986, 0.988, 0.99.

[0036] In some embodiments of the present invention, y is selected from any value or a range of values ​​formed by any two of the following: 0.01, 0.012, 0.014, 0.016, 0.018, 0.02, 0.022, 0.024, 0.026, 0.028, 0.03, 0.032, 0.034, 0.036, 0.038, 0.04, 0.042, 0.044, 0.046, 0.048, and 0.05.

[0037] In some embodiments of the present invention, the doped lithium cobalt oxide matrix is ​​selected from LiCo. 0.962 Al 0.020 Mg 0.010 Ti 0.004 Zr 0.004 O2, LiCo 0.962 Al 0.020 Mg 0.010 Y 0.008 O2, LiCo 0.962 Al 0.020 Mg 0.010 Ti 0.008 O2 or LiCo 0.990 Al 0.004 Mg 0.002 Ti 0.002 Zr 0.002 O2.

[0038] In some embodiments of the present invention, the content of M gradually decreases from the surface of the doped lithium cobalt oxide matrix to the interior of the doped lithium cobalt oxide matrix. The present invention reduces lattice distortion energy, alleviates lattice stress, and improves the structural stability of lithium cobalt oxide materials by enabling a gradient distribution of the dopant element M within the lithium cobalt oxide matrix.

[0039] In some embodiments of the present invention, the atomic percentage of M on the surface of the doped lithium cobalt oxide substrate is 0.8 to 4.0, based on the total number of Co atoms in LiCoO2. at%; In some embodiments of the present invention, the atomic percentage of M on the surface of the doped lithium cobalt oxide matrix, based on the total number of Co atoms in LiCoO2, is any value or a range formed by any two of the following: 0.8at%, 0.9at%, 1.0at%, 1.1at%, 1.2at%, 1.3at%, 1.4at%, 1.5at%, 1.6at%, 1.7at%, 1.8at%, 1.9at%, 2.0at%, 2.1at%, 2.2at%, 2.3at%, 2.4at%, 2.5at%, 2.6at%, 2.7at%, 2.8at%, 2.9at%, 3.0at%, 3.1at%, 3.2at%, 3.3at%, 3.4at%, 3.5at%, 3.6at%, 3.7at%, 3.8at%, 3.9at%, 4.0at%.

[0040] In some embodiments of the present invention, the atomic percentage of M inside the doped lithium cobalt oxide matrix is ​​0.2 to 1.0 at%, based on the total number of Co atoms in LiCoO2; in some embodiments of the present invention, the atomic percentage of M inside the doped lithium cobalt oxide matrix is ​​any value or a range formed by any two of the following: 0.2 at%, 0.3 at%, 0.4 at%, 0.5 at%, 0.6 at%, 0.7 at%, 0.8 at%, 0.9 at%, and 1.0 at%.

[0041] In some embodiments of the present invention, the inner cladding layer is a composite layer of LiF and AlF3.

[0042] In some embodiments of the present invention, the molar ratio of LiF to AlF3 is 1:(1~3); in some specific embodiments of the present invention, the molar ratio of LiF to AlF3 is any value or a range formed by any two of the following: 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, 1:3.

[0043] In some embodiments of the present invention, the thickness of the outer coating layer is 5-10 nm; in some specific embodiments of the present invention, the thickness of the outer coating layer is any value of 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm or a range formed by any two of them.

[0044] In some embodiments of the present invention, the thickness of the inner coating layer is 2-5 nm; in some specific embodiments of the present invention, the thickness of the inner coating layer is any value of 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm or a range formed by any two of them.

[0045] In some embodiments of the present invention, M is selected from Al, Mg, Ti and Zr.

[0046] In some embodiments of the present invention, the molar ratio of Al to Zr is (1~25):1; in some specific embodiments of the present invention, the molar ratio of Al to Zr is any value or a range formed by any two of the following: 1:1, 2:1, 4:1, 6:1, 8:1, 10:1, 12:1, 14:1, 16:1, 18:1, 20:1, 22:1, 24:1, 25:1.

[0047] In some embodiments of the present invention, the molar ratio of Mg to Zr is (0.5~15):1; in some specific embodiments of the present invention, the molar ratio of Mg to Zr is any value or a range formed by any two of the following: 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1.

[0048] In some embodiments of the present invention, the molar ratio of Ti to Zr is (0.4~8):1; in some specific embodiments of the present invention, the molar ratio of Ti to Zr is any value or a range formed by any two of the following: 0.4:1, 0.6:1, 0.8:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1.

[0049] In some embodiments of the present invention, a method for preparing a positive electrode material is provided, comprising the following steps: The raw materials used to prepare the cathode material are mixed and ground to obtain precursor powder; The precursor powder was plasma activated in an oxygen-containing atmosphere to obtain the activated precursor. The activated precursor was first calcined in an oxygen-containing atmosphere, and then calcined a second time in AlF3 vapor to obtain the cathode material.

[0050] The preparation method of this invention involves plasma activation of the precursor powder in an oxygen-containing atmosphere, followed by ionization of the oxygen-containing atmosphere under a high-frequency electric field to generate high-energy oxygen free radicals O. - and ionic phosphide PO4 3- Its core mechanism and function is O - 5eV energy is used to bombard the surface, filling oxygen defect sites and suppressing oxygen release during high-voltage cycling of the cathode material, PO4 3- Directional implantation forms an amorphous Li3PO4 pre-coating, providing a template for crystallization during sintering; plasma energy drives Li⁺ to migrate to the surface, reducing sintering lithium loss and lowering residual alkali content. During the O2 plasma activation stage, high-energy oxygen free radicals O₂... - Remove surface protons to form hydroxyl-free Li + When AlF3 steam is subsequently introduced into the terminal Li3PO4 layer, due to the terminal Li + The reaction barrier with AlF3 is as high as 1.53 eV, and the negative bias of the plasma sheath repels polar AlF3 molecules. This dual effect blocks the residual reaction of AlF3 on the surface of the Li3PO4 layer. At the same time, the dense crystalline layer suppresses the diffusion coefficient of AlF3 to 10. -12 m 2 The vapor density is on the order of / s, ensuring that it diffuses only into the internal interface, thereby allowing AlF3 vapor to pass through the outer coating of Li3PO4 and enter its interior to form an inner coating composed of LiF and AlF3.

[0051] In some embodiments of the present invention, the oxygen-containing atmosphere during the first calcination can be selected from at least one of air and oxygen.

[0052] In some embodiments of the present invention, the raw materials used to prepare the cathode material include a cobalt source, a lithium source, a phosphorus source, and an M source.

[0053] In some embodiments of the present invention, the lithium source is selected from at least one of lithium carbonate, lithium phosphate, and lithium hydroxide.

[0054] In some embodiments of the present invention, the cobalt source is selected from at least one of cobalt tetroxide, cobalt carbonate, cobalt hydroxide, cobalt monoxide, cobalt sulfate, cobalt oxalate, cobalt nitrate, and cobalt chloride.

[0055] In some embodiments of the present invention, the phosphorus source is selected from at least one of lithium phosphate, ammonium dihydrogen phosphate, aluminum phosphate, and cobalt phosphate.

[0056] In some embodiments of the present invention, when M is selected from Al, Mg, Ti and Zr, the source of M is selected from aluminum hydroxide, magnesium oxide, TiO2 and ZrO2.

[0057] In some embodiments of the present invention, when the lithium source is lithium carbonate and the cobalt source is cobalt tetroxide, the molar ratio of lithium carbonate to cobalt tetroxide is 1:(0.5~0.7).

[0058] In some embodiments of the present invention, the cobalt source is cobalt tetroxide, and the molar ratio of cobalt tetroxide to phosphorus source is 1:(0.01~0.10).

[0059] In some embodiments of the present invention, the cobalt source is cobalt tetroxide, and the molar ratio of cobalt tetroxide to M source is 1:(0.01~0.30).

[0060] In some embodiments of the present invention, the particle size of the precursor powder is 10~18μm; in some embodiments of the present invention, the particle size of the precursor powder is any value of 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm or a range formed by any two of them.

[0061] In some embodiments of the present invention, the preparation method further includes a water washing step; the water washing step is performed after the second calcination step. The water washing step is mainly to remove residual alkali from the cathode material.

[0062] In some embodiments of the present invention, the mass percentage of residual alkali contained in the cathode material is ≤0.1%.

[0063] In some embodiments of the present invention, the residual alkali includes lithium carbonate and lithium hydroxide.

[0064] In some embodiments of the present invention, the radio frequency used in plasma activation is 10~15MHz; in some specific embodiments of the present invention, the radio frequency used in plasma activation is any value of 10MHz, 11MHz, 12MHz, 13MHz, 14MHz, 15MHz or a range formed by any two of them.

[0065] In some embodiments of the present invention, the gas pressure during plasma activation is 30~60 Pa; in some specific embodiments of the present invention, the gas pressure during plasma activation is any value or a range formed by any two of the following: 30 Pa, 32 Pa, 34 Pa, 36 Pa, 38 Pa, 40 Pa, 42 Pa, 44 Pa, 46 Pa, 48 Pa, 50 Pa, 52 Pa, 54 Pa, 56 Pa, 58 Pa, 60 Pa.

[0066] In some embodiments of the present invention, the plasma power in plasma activation is 200~800W; in some specific embodiments of the present invention, the plasma power in plasma activation is any value of 200W, 300W, 400W, 500W, 600W, 700W, 800W, or a range formed by any two of them.

[0067] In some embodiments of the present invention, the plasma activation time is 10-30 min; in some specific embodiments of the present invention, the plasma activation time is any value of 10 min, 15 min, 20 min, 25 min, 30 min, or a range formed by any two of them.

[0068] In some embodiments of the present invention, the oxygen-containing plasma atmosphere in plasma activation is a mixture of oxygen and at least one selected from nitrogen and inert gases.

[0069] In some embodiments of the present invention, the inert gas is selected from at least one of argon and helium.

[0070] In some embodiments of the present invention, the oxygen-containing plasma atmosphere in plasma activation is a mixture of oxygen and argon in a volume ratio of 1:(3~5).

[0071] In some embodiments of the present invention, the temperatures of the first calcination and the second calcination are 450~1050℃, respectively.

[0072] In some embodiments of the present invention, the temperature of the first calcination is 800~1050℃; in some specific embodiments of the present invention, the temperature of the first calcination is any value of 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, or a range formed by any two of these values.

[0073] In some embodiments of the present invention, the temperature of the second calcination is 450~550℃; in some specific embodiments of the present invention, the temperature of the second calcination is any value or a range formed by any two of 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃, 540℃, and 550℃.

[0074] In some embodiments of the present invention, the partial pressure of AlF3 vapor is 0.1~0.3 atm; in some specific embodiments of the present invention, the partial pressure of AlF3 vapor is any value of 0.1 atm, 0.15 atm, 0.2 atm, 0.25 atm, 0.3 atm, or a range formed by any two of them.

[0075] In some embodiments of the present invention, during the first calcination, the temperature of the surface of the doped lithium cobalt oxide substrate is 30-80°C higher than the temperature inside the doped lithium cobalt oxide substrate; in some specific embodiments of the present invention, the temperature of the surface of the doped lithium cobalt oxide substrate is any value or a range formed by any two of 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, and 80°C higher than the temperature inside the doped lithium cobalt oxide substrate.

[0076] In some embodiments of the present invention, during the second calcination, the temperature of the surface of the doped lithium cobalt oxide substrate is 30-80°C higher than the temperature inside the doped lithium cobalt oxide substrate; in some specific embodiments of the present invention, the temperature of the surface of the doped lithium cobalt oxide substrate is any value or a range formed by any two of 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, and 80°C higher than the temperature inside the doped lithium cobalt oxide substrate.

[0077] In this invention, during the first and / or second calcination processes, the higher temperature of the activated precursor surface is beneficial for increasing the Al / Mg diffusion coefficient, promoting its enrichment on the lithium cobalt oxide matrix surface. Conversely, the lower temperature inside the activated precursor inhibits Ti / Zr diffusion, thus maintaining a low concentration of dopant elements inside the doped lithium cobalt oxide matrix and a high concentration of dopant elements on the matrix surface, thereby forming a dopant element concentration gradient distribution within the doped lithium cobalt oxide matrix. This invention achieves gradient doping of dopant elements and the formation of inner and outer coating layers in the lithium cobalt oxide matrix by setting the atmosphere during the first and second calcinations. When the first calcination is performed at 800-1050℃ with an oxygen atmosphere, the Li on the surface of the lithium cobalt oxide matrix... + and PO4 3- A continuous Li3PO4 outer coating is formed. When the temperature is lowered to 450~550℃, AlF3 vapor is introduced. The gaseous AlF3 permeates through the gaps in the Li3PO4 outer coating and interacts with the Li lattice. + The reaction generates a composite inner coating layer of LiF-AlF3, thereby forming a gradient structure of an outer coating layer of Li3PO4 and a composite inner coating layer of LiF-AlF3.

[0078] In some embodiments of the present invention, the present invention also provides a product comprising the above-described positive electrode material.

[0079] In some embodiments of the present invention, the present invention also provides an electrical device containing a battery, wherein the battery in the electrical device contains the aforementioned positive electrode material.

[0080] The specific implementation of the present invention will be further described in detail below with reference to specific embodiments: In the following examples and comparative examples, the solid-liquid ratio refers to the mass ratio of solid to liquid.

[0081] The chemical formula, inner coating layer, outer coating layer, and dopant element content of the lithium cobalt oxide cathode materials involved in the following examples and comparative examples were all characterized by elemental ICP and EDS tests.

[0082] Example 1 This example provides a lithium cobalt oxide cathode material, which consists of, from the inside out, a doped lithium cobalt oxide matrix, a LiF-AlF3 inner coating layer, and a Li3PO4 outer coating layer. The chemical formula of the doped lithium cobalt oxide matrix is ​​LiCo. 0.962 Al 0.020 Mg 0.010 Ti 0.004 Zr 0.004 O2. The LiF-AlF3 inner coating layer is a composite layer of LiF and AlF3, wherein the molar ratio of LiF to AlF3 is 3:1; Based on the total number of Co atoms in LiCoO2, the atomic percentage of doping elements (i.e., Al, Mg, Ti, Zr) on the surface of the doped lithium cobalt oxide matrix is ​​3.0 at, and the atomic percentage of doping elements (i.e., Al, Mg, Ti, Zr) inside it is 0.8 at.

[0083] This example provides a method for preparing a lithium cobalt oxide cathode material, specifically including the following steps: (1) Preparation of precursor: The raw materials Li2CO3, Co3O4, Li3PO4, Al(OH)3, MgO, TiO2 and ZrO2 were weighed in a molar ratio of 1.000:0.611:0.0142:0.0200:0.0100:0.0040:0.0040 to obtain solids; then they were ball-milled with anhydrous ethanol in a planetary ball mill at a ball milling speed of 400 rpm for 6 h at a solid-liquid ratio of 1:5. The mixed material was vacuum dried at 80℃ for 12 h and passed through a 200-mesh sieve to obtain uniform precursor powder. (2) Plasma activation: The precursor powder was placed in the radio frequency plasma reaction chamber and treated for 20 min under an atmosphere with a volume ratio of Ar to O2 of 4:1, a radio frequency of 15 MHz, a power of 500 W, and a pressure of 50 Pa to obtain the activated precursor. (3) Gradient sintering: The activated precursor is placed in a multi-temperature zone sintering furnace for gradient sintering. The temperature is raised to 980℃ at a rate of 5℃ / min. After reaching the temperature, oxygen is introduced at a rate of 50mL / min and the temperature is held for 12h to generate an outer coating of Li3PO4. After the holding period, the temperature is lowered to 500℃, and then AlF3 vapor with a partial pressure of 0.2 standard atmospheres (atm) evaporated at 300℃ is introduced and the temperature is held for 2h to generate an inner coating of LiF-AlF3, thus obtaining the sintered lithium cobalt oxide material. (4) Post-treatment: The sintered lithium cobalt oxide material was washed with deionized water at a solid-liquid ratio of 1:10 for 30 min, and then vacuum dried at 60°C to reduce residual alkali, thus obtaining the lithium cobalt oxide cathode material in this example.

[0084] Example 2 This example provides a lithium cobalt oxide cathode material, which consists of, from the inside out, a doped lithium cobalt oxide matrix, a LiF-AlF3 inner coating layer, and a Li3PO4 outer coating layer. The chemical formula of the doped lithium cobalt oxide matrix is ​​LiCo. 0.962 Al 0.020 Mg 0.010 Ti 0.004 Zr 0.004 O2: The LiF-AlF3 inner coating layer is a composite layer of LiF and AlF3, wherein the molar ratio of LiF to AlF3 is 3:1. Based on the total number of Co atoms in LiCoO2, the atomic percentage of doping elements (i.e., Al, Mg, Ti, Zr) on the surface of the doped lithium cobalt oxide matrix is ​​3.0 at, and the atomic percentage of doping elements (i.e., Al, Mg, Ti, Zr) inside the doped lithium cobalt oxide matrix is ​​0.8 at.

[0085] This example provides a method for preparing a lithium cobalt oxide cathode material, specifically including the following steps: (1) Preparation of precursor: Lithium carbonate, 30% by mass of regenerated lithium cobalt oxide, 68.7% by mass of Co3O4 nanopowder, 1.3% by mass of Li3PO4, Al(OH)3, MgO, TiO2, and ZrO2 were weighed and mixed in a molar ratio of 1.000:0.6602:0.6145:0.0241:0.0521:0.0261:0.0103:0.0103. The above molar ratio was measured according to the number of moles of lithium cobalt oxide, the number of moles of Co3O4, and the number of moles of Li3PO4 to obtain solid powder. Then, it was ball-milled with anhydrous ethanol in a planetary ball mill at a ball milling rate of 400 rpm for 6 h at a solid-liquid ratio of 1:5. The mixed material was vacuum dried at 80℃ for 12 h and passed through a 200-mesh sieve to obtain uniform precursor powder. (2) Plasma activation: The precursor powder was placed in the radio frequency plasma reaction chamber and treated for 20 min at a volume ratio of Ar to O2 of 4:1, a radio frequency of 15 MHz, a power of 500 W, and a pressure of 50 Pa to obtain the activated precursor. (3) Gradient sintering: The activated precursor was placed in a multi-temperature zone sintering furnace for gradient sintering. The temperature was increased to 980℃ at a rate of 5℃ / min. After reaching the temperature, oxygen was introduced at a rate of 50mL / min and the temperature was held for 12h to generate an outer coating of Li3PO4. After the holding period, the temperature was lowered to 500℃, and then AlF3 vapor, which evaporates at 300℃ and has a partial pressure of 0.2atm, was introduced and the temperature was held for 2h to generate an inner coating of LiF-AlF3, thus obtaining the sintered lithium cobalt oxide material. (4) Post-treatment: The sintered lithium cobalt oxide material is washed with deionized water at a solid-liquid ratio of 1:10 for 30 min, and then vacuum dried at 60℃ to reduce residual alkali, thereby obtaining the lithium cobalt oxide cathode material in this example.

[0086] Example 3 This example provides a lithium cobalt oxide cathode material, which consists of, from the inside out, a doped lithium cobalt oxide matrix, a LiF-AlF3 inner coating layer, and a Li3PO4 outer coating layer. The chemical formula of the doped lithium cobalt oxide matrix is: LiCo 0.962 Al 0.020 Mg 0.010 Ti 0.00 4Zr 0.004 O2. The LiF-AlF3 inner coating layer is a composite layer of LiF and AlF3, wherein the molar ratio of LiF to AlF3 is 3:1. Based on the total number of Co atoms in LiCoO2, the atomic percentage of doping elements (i.e., Al, Mg, Ti, Zr) on the surface of the doped lithium cobalt oxide matrix is ​​3.0 at, and the atomic percentage of doping elements (i.e., Al, Mg, Ti, Zr) inside the doped lithium cobalt oxide matrix is ​​0.8 at.

[0087] This example provides a method for preparing a lithium cobalt oxide cathode material, specifically including the following steps: (1) Preparation of precursor: Lithium carbonate, 50% by mass of regenerated lithium cobalt oxide, 48.7% by mass of Co3O4 nanopowder, 1.3% by mass of Li3PO4, Al(OH)3, MgO, TiO2, and ZrO2 were weighed and mixed in a molar ratio of 1.0000:1.1010:0.4356:0.0241:0.0521:0.0261:0.0103:0.0103. The above molar ratio was measured according to the molar number of lithium cobalt oxide, the molar number of Co3O4, and the molar number of Li3PO4 to obtain a solid powder. Then, it was mixed with anhydrous ethanol at a solid-liquid ratio of 1:5 in a planetary ball mill at a ball milling rate of 400 rpm for 8 h. The mixed material was vacuum dried at 80℃ for 12 h and passed through a 200-mesh sieve to obtain a uniform precursor powder. (2) Plasma activation: The difference between step (2) in this example and step (2) in Example 1 is that the power is adjusted to 600W and the processing time is adjusted to 30min in this example, in order to enhance the repair of surface defects. (3) Gradient sintering: The difference between this step and Example 1 is that the sintering temperature is 975℃ and the partial pressure of AlF3 vapor is adjusted to 0.15atm in order to suppress excessive reaction. (4) Post-processing: The difference between this step and Example 1 is that the water washing time is extended to 45 min to ensure that the mass percentage of residual alkali in the lithium cobalt oxide cathode material is ≤0.1%. Example 4 This example provides a lithium cobalt oxide cathode material, which consists of, from the inside out, a doped lithium cobalt oxide matrix, a LiF-AlF3 inner coating layer, and a Li3PO4 outer coating layer. The chemical formula of the doped lithium cobalt oxide matrix is: LiCo 0.990 Al 0.004 Mg 0.002 Ti 0.00 2Zr 0.002 O2. The LiF-AlF3 inner coating layer is a composite layer of LiF and AlF3, wherein the molar ratio of LiF to AlF3 is 3:1. Based on the total number of Co atoms in LiCoO2, the atomic percentage of doping elements (i.e., Al, Mg, Ti, Zr) on the surface of the doped lithium cobalt oxide matrix is ​​0.8 at, and the atomic percentage of doping elements (i.e., Al, Mg, Ti, Zr) inside the doped lithium cobalt oxide matrix is ​​0.2 at.

[0088] This example provides a method for preparing a lithium cobalt oxide cathode material, specifically including the following steps: (1) Preparation of precursor: Lithium carbonate, Co3O4 nanopowder with a mass percentage of 99.7%, Li3PO4, Al(OH)3, MgO, TiO2 and ZrO2 with a mass percentage of 1.3% were weighed and mixed in a molar ratio of 1.0000:0.6410:0.0142:0.0080:0.0040:0.0040:0.0040. The above molar ratio was measured according to the molar number of Co3O4 and the molar number of Li3PO4 to obtain solid powder; then it was mixed with anhydrous ethanol at a solid-liquid ratio of 1:5 in a planetary ball mill at a ball milling rate of 400 rpm for 8 h. The mixed material was vacuum dried at 80℃ for 12 h and passed through a 200 mesh sieve to obtain uniform precursor powder; (2) Plasma activation: The difference between this step and Example 1 is that the power is 400W and the processing time is 15min, which is to adapt to low doping concentration. (3) Gradient sintering: The difference between this step and Example 1 is that the sintering temperature is 970℃ and the AlF3 vapor partial pressure is 0.1atm. (4) Post-treatment: The water washing conditions are the same as in Example 1.

[0089] Example 5 This example provides a lithium cobalt oxide cathode material, which consists of, from the inside out, a doped lithium cobalt oxide matrix, a LiF-AlF3 inner coating layer, and a Li3PO4 outer coating layer. The chemical formula of the doped lithium cobalt oxide matrix is ​​LiCo. 0.962 Al 0.020 Mg 0.010 Ti 0.008 O2. The inner coating of LiF-AlF3 is a composite layer of LiF and AlF3, wherein the molar ratio of LiF to AlF3 is 3:1; Based on the total number of atoms in the doped lithium cobalt oxide matrix, the atomic percentage of doping elements (i.e., Al, Mg, Ti) on the surface of the doped lithium cobalt oxide matrix is ​​3.0 at, and the atomic percentage of doping elements (i.e., Al, Mg, Ti) inside it is 0.8 at.

[0090] The difference between the preparation method of lithium cobalt oxide cathode material in this example and that in Example 1 is that ZrO2 is not added in step (1) of this example. Step (1) of this example is as follows: Precursor preparation: Li2CO3, Co3O4, Li3PO4, Al(OH)3, MgO and TiO2 are weighed and mixed in a molar ratio of 1.000:0.611:0.0142:0.0200:0.0100:0.0080 to obtain a solid. Then, it is ball-milled with anhydrous ethanol in a planetary ball mill at a ball milling speed of 400 rpm for 6 h at a solid-liquid ratio of 1:5. The mixed material is vacuum dried at 80℃ for 12 h and passed through a 200-mesh sieve to obtain a uniform precursor powder.

[0091] Example 6 This example provides a lithium cobalt oxide cathode material, which consists of, from the inside out, a doped lithium cobalt oxide matrix, a LiF-AlF3 inner coating layer, and a Li3PO4 outer coating layer. The chemical formula of the doped lithium cobalt oxide matrix is ​​LiCo. 0.962 Al 0.020 Mg 0.010 Y 0.008 O2. The inner coating of LiF-AlF3 is a composite layer of LiF and AlF3, wherein the molar ratio of LiF to AlF3 is 3:1; Based on the total number of Co atoms in LiCoO2, the atomic percentage of doping elements (i.e., Al, Mg, Y) on the surface of the doped lithium cobalt oxide matrix is ​​3.0 at, and the atomic percentage of doping elements (i.e., Al, Mg, Y) inside it is 0.8 at.

[0092] The difference between the preparation method of lithium cobalt oxide cathode material in this example and that in Example 1 is only that the doping elements in step (1) of this example are Al, Mg and Y. Step (1) of this example is: Precursor preparation: The raw materials Li2CO3, Co3O4, Li3PO4, Al(OH)3, MgO and Y2O3 are weighed and mixed in a molar ratio of 1.000:0.6138:0.0142:0.0200:0.0100:0.0031 to obtain a solid; then it is ball-milled with anhydrous ethanol in a planetary ball mill at a ball milling speed of 400 rpm for 6 h at a solid-liquid ratio of 1:5. The mixed material is vacuum dried at 80℃ for 12 h and passed through a 200-mesh sieve to obtain a uniform precursor powder.

[0093] Comparative Example 1 This example provides a method for preparing a lithium cobalt oxide cathode material, specifically including the following steps: (1) Preparation of precursor: 1.02 mol of Li2CO3, 0.97 mol of Co3O4 and 0.02 mol of Al(OH)3 were mixed to obtain a solid. Then, the solid was mixed with anhydrous ethanol at a solid-liquid ratio of 1:5 in a planetary ball mill at a ball milling rate of 400 rpm for 6 h. The mixed material was vacuum dried at 80 °C for 12 h and passed through a 200 mesh sieve to obtain a uniform precursor powder. (2) Sintering: The precursor powder is placed in a multi-temperature zone sintering furnace for gradient sintering. The temperature is raised to a stable 980℃ at a heating rate of 5℃ / min and held for 12h. O2 is introduced during the sintering process to generate Al-doped LiCoO2 matrix. (3) LiAlO2 coating: The Al-doped LiCoO2 substrate is immersed in aluminum nitrate solution, dried, and then sintered at 800°C for 2 hours in an oxygen atmosphere to form a LiAlO2 coating layer with a thickness of about 10 nm.

[0094] The lithium cobalt oxide cathode material in this example is doped with Al as a single element and coated with a LiAlO2 coating layer. (Comparative Example 2) The difference between the preparation method of lithium cobalt oxide cathode material in this example and that in Example 1 is that step (2) is omitted in this example. In this example, the precursor powder obtained in step (1) is directly subjected to gradient sintering and then post-processing.

[0095] Comparative Example 3 The only difference between the lithium cobalt oxide cathode material in this example and that in Example 1 is that this example uses only four elements—Al, Mg, Ti, and Zr—for doping, without the Li3PO4 coating layer or the LiF-AlF3 coating layer.

[0096] Comparative Example 4 The only difference between the preparation method of lithium cobalt oxide cathode material in this example and that in Example 1 is that the plasma power in step (2) of this example is adjusted to 700W.

[0097] Comparative Example 5 The difference between the preparation method of lithium cobalt oxide cathode material in this example and that in Example 1 is only that: in this example, step (3) is: the activated precursor is placed in a multi-temperature zone sintering furnace for gradient sintering, the temperature is raised to 500°C at a rate of 5°C / min, AlF3 vapor with a partial pressure of 0.2 standard atmospheres (atm) evaporated at 300°C is introduced, and the temperature is kept for 2 hours to generate an inner coating layer of LiF-AlF3. Then, when the temperature is raised to 980°C at a rate of 5°C / min, NH4H2PO4 precursor is introduced and oxygen is introduced at a rate of 50 mL / min and kept for 12 hours to form an outer coating layer of Li3PO4.

[0098] Performance testing: The lithium cobalt oxide cathode material prepared in Example 1 was analyzed using a field emission scanning electron microscope (FET) with an Oxford energy dispersive spectroscopy (EDS) instrument to obtain an EDS line scan from the surface of the lithium cobalt oxide material to the substrate. The accelerating voltage was 15 kV and the beam current was 10 nA. After argon ion polishing, the sample was sprayed with a 5 nm carbon film. A vertical scan of 50 nm was performed along the particle cross-section with a step size of 5 nm and a dwell time of 100 ms. The elemental distribution of Co, P, Mg, Al, Ti, and Zr was quantitatively analyzed. The calibration was performed using NIST standard samples to ensure an error of <2 at%. at% refers to atomic percentage, which is used to express the percentage of a certain isotope atoms out of the total number of atoms of that element. The test results obtained according to the above testing method are shown in the figure. Figure 1 As shown. By Figure 1It is evident that the P element exhibits a significant signal peak in the 0-8 nm range, with the peak value located at 4 nm, consistent with the designed thickness of 5-10 nm for the Li3PO4 coating layer. Furthermore, the O element signal shows a synchronous increase in the 0-8 nm range, consistent with the designed thickness, confirming the formation of the Li3PO4 outer coating layer. The F element signal shows a sudden increase in the 8-11 nm range, with the Al element signal increasing synchronously. The F to Al atomic ratio is approximately 6:1, demonstrating the existence of the LiF-AlF3 inner coating layer. The P and F element signals are located in the 0-8 nm and 8-11 nm ranges, respectively, clearly verifying the layered structure and precise thickness control of the dual-gradient coating layer. The concentrations of the four doping elements (Al, Mg, Ti, and Zr) gradually decrease from the surface of the lithium cobalt oxide substrate to the bulk phase, further verifying that a gradient distribution of the four doping elements is formed in the lithium cobalt oxide cathode material of Example 1, with no doping observed in the coating layer. This gradient doping structure of the four doping elements can better achieve the stress buffering function.

[0099] The lithium cobalt oxide cathode materials prepared in Example 1 and Comparative Example 1 were subjected to XRD analysis using a Bruker D8 Advance diffractometer with a scanning range of 10°–80°, a step size of 0.02°, and a speed of 2° / min. TOPAS V7 was used to refine and calculate the cell parameters and site defects. The test results are as follows: Figure 2 As shown. By Figure 2 It can be seen that the quaternary high-entropy design of Example 1 balances the difference in atomic radius and the lattice distortion rate is <1%; at the same time, the dual gradient coating stabilizes the structure and suppresses the high-pressure phase transition (H1-3 phase), and the (108) and (110) peaks remain split; and the structure maintains its integrity under long cycles, and the intensity retention rate of the (003) peak is >95% after 1000 cycles, with no impurity phase generated.

[0100] The lithium cobalt oxide cathode material in Example 1 was examined using a scanning electron microscope (SEM) at 1000x magnification, as shown in the image below. Figure 3 As shown. By Figure 3 It can be seen that the particle size D50 of the lithium cobalt oxide cathode material prepared in Example 1 is about 10~20μm. It is a spherical or near-spherical particle with a relatively uniform particle size distribution and a dense layer without cracks on the surface.

[0101] The lithium cobalt oxide cathode materials prepared in Examples 1-5 and Comparative Examples 1-5 were respectively mixed with conductive carbon black and polyvinylidene fluoride (PVDF) at a mass ratio of 0.92:0.04:0.04 to form slurries. These slurries were then coated onto aluminum foil, dried, and used as the cathode. The anode was a lithium metal sheet, the separator was Celgard 2500, and the electrolyte was 1... A CR2032 button cell was constructed using a 1:1 volume ratio of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a LiPF6 solution and a 1 mol / L LiPF6 solution. Performance testing was then conducted using the following methods: constant current charge-discharge at 25±1℃ and a voltage plateau of 3.0–4.6V; discharge specific capacity was tested at 0.1C; cycle retention was tested at 0.5C under a voltage plateau of 3.0–4.6V, calculated as (1000th cycle capacity / initial capacity) × 100%; oxygen vacancy concentration was calculated using X-ray photoelectron spectroscopy (XPS) based on the area ratio of the 531.5 eV peak in the O1s spectrum; and electrochemical impedance spectroscopy (EIS) was used to analyze the 0.1–10 mol / L LiPF6 solution. 6 The interface impedance was tested by fitting the Rsei value with an amplitude of Hz / 10 mV. After the battery was cycled, the positive electrode was disassembled, and the Co content in the electrolyte was detected by inductively coupled plasma mass spectrometry (ICP-MS) to test the Co dissolution. The results obtained by the above test method are shown in Table 1 below.

[0102] Table 1 Performance test results of batteries containing lithium cobalt oxide cathode materials

[0103] As shown in Table 1, compared with Comparative Examples 1-5, the batteries assembled using the lithium cobalt oxide cathode material in Examples 1-5 exhibit higher initial discharge capacity, higher capacity retention during cycling at a high voltage of 4.6V, lower oxygen vacancy concentration, lower interfacial impedance, and lower Co dissolution. Specifically, the initial discharge capacity is 233-247 mAh / g, the capacity retention after 1000 cycles at 3.0-4.6V is 83.1-89.3%, the oxygen vacancy concentration is 5.3-7.2%, and the interfacial impedance is 4.7-10.5 Ωcm. 2 The Co leaching amount is 0.8~2.5 μg / cm³. 2Among them, Example 1 achieved an initial discharge capacity of 247 mAh / g at 4.6V, which is close to 93% of the theoretical capacity of 265 mAh / g and significantly better than the 238 mAh / g of Comparative Example 2. The cycle retention rate of Example 1 was 10.8% higher than that of Comparative Example 1, proving the long-term stability of the gradient design. The oxygen vacancy concentration of Example 1 was only 36% of that of Comparative Example 1, indicating that the Li3PO4 coating effectively suppressed oxygen loss. The interfacial impedance of Example 1 was 1 / 5 of that of Comparative Example 1, which corroborates that the LiF-AlF3 layer optimized lithium-ion transport. The Co dissolution of Example 1 was only 18% of that of Comparative Example 1, confirming that the double coating layer has a significant effect on blocking HF corrosion and can reduce the dissolution of Co.

[0104] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A cathode material, characterized in that: It includes a doped lithium cobalt oxide substrate, an inner coating layer, and an outer coating layer; the surface of the doped lithium cobalt oxide substrate is provided with an inner coating layer, and the surface of the inner coating layer is provided with an outer coating layer; The doped lithium cobalt oxide matrix is ​​LiCo. x M y O2, 0.95≤x≤0.99, 0.01≤y≤0.05, x+y=1; M is selected from at least one of Al, Mg, Ti, Zr, La, Y, Se, W, P, Na, Ca, Se, Sc, V, Cr, Nd, Zn, Ni, Mn, and B; The inner coating layer contains LiF and AlF3; The outer coating layer contains Li3PO4.

2. The cathode material according to claim 1, characterized in that: The content of M gradually decreases from the surface of the doped lithium cobalt oxide matrix to the interior of the doped lithium cobalt oxide matrix.

3. The cathode material according to claim 2, characterized in that: Based on the total number of Co atoms in LiCoO2, the atomic percentage of M on the surface of the doped lithium cobalt oxide substrate is 0.8~4.0 at% And / or, based on the total number of Co atoms in LiCoO2, the atomic percentage of M within the doped lithium cobalt oxide matrix is ​​0.2 to 1.0 at.

4. The cathode material according to claim 1, characterized in that: The molar ratio of LiF to AlF3 is 1:(1~3).

5. The cathode material according to claim 1, characterized in that: The thickness of the outer coating layer is 5~10 nm; and / or, the thickness of the inner coating layer is 2~5 nm.

6. The cathode material according to claim 1, characterized in that: The M is selected from Al, Mg, Ti and Zr; the molar ratio of Al to Zr is (1~25):1; the molar ratio of Mg to Zr is (0.5~15):1; the molar ratio of Ti to Zr is (0.4~8):

1.

7. The method for preparing the cathode material according to any one of claims 1 to 6, characterized in that: Includes the following steps: The raw materials used to prepare the cathode material are mixed and ground to obtain precursor powder; The precursor powder was plasma activated in an oxygen-containing atmosphere to obtain the activated precursor. The activated precursor was first calcined in an oxygen-containing atmosphere, and then calcined a second time in AlF3 vapor to obtain the cathode material.

8. The method for preparing the cathode material according to claim 7, characterized in that: The plasma activation has at least one of the following characteristics: (1) The radio frequency used in the plasma activation is 10~15 MHz; (2) The gas pressure during plasma activation is 30~60 Pa; (3) The plasma power in the plasma activation is 200~800W; (4) The plasma activation time is 10~30 min; (5) The oxygen-containing atmosphere in the plasma activation is a mixture of oxygen and at least one selected from nitrogen and inert gases.

9. The method for preparing the cathode material according to claim 7, characterized in that: The temperature of the first calcination is 800-1050℃; And / or, the temperature of the second calcination is 450-550℃; And / or, the partial pressure of the AlF3 vapor is 0.1~0.3 atm; And / or, during the first calcination and / or the second calcination, the temperature of the surface of the doped lithium cobalt oxide matrix is ​​30-80°C higher than the temperature inside the doped lithium cobalt oxide matrix.

10. A product, characterized in that: The product includes the positive electrode material as described in any one of claims 1 to 6; the product includes a battery or an electrical device containing a battery.

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