Composite positive electrode material with oxygen permeation layer and preparation method and application thereof

Abstract

The application provides a composite positive electrode material with a nano-oxygen permeation layer and a preparation method and application thereof. γ A a B b O 3+1 / 2γ‑δ , 0 < gamma < 2, 0.9 <= a <= 1, 0.9 <= b <= 1, 1.8 <= a + b <= 2, 0.001 <= delta <= 0.1, the A element includes La, Ce, Ln, Y, Sr or Pr, and the B element contains Ni, Co, Mn, Cu, Fe, Al, Zr, Nb, Ag, Ti or Ta. The application sets the nano-oxygen permeation layer as an oxygen containing layer by arranging the nano-oxygen permeation layer which is gradiently diffused from the surface to the core on the surface of the lithium-rich material matrix, prevents the active oxygen generated due to the irreversible reaction on the surface of the lithium-rich material from being released in the form of oxygen, and improves the safety and service life of the battery.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to cathode materials, and more particularly to a composite cathode material with a nano-oxygen permeation layer, its preparation method, and its application. Background Technology

[0002] Lithium-rich materials have become highly sought-after battery cathode materials due to their high energy density, low cost, and relatively good safety. Their theoretical energy density far exceeds that of traditional cathode materials, making it possible to improve the driving range of electric vehicles and meeting the market's expectations for long-range electric vehicles.

[0003] However, during charging and discharging, lithium-rich materials, due to their reactive surface chemistry, are prone to side reactions with the electrolyte, generating gases such as carbon dioxide and carbon monoxide. The generation of these gases increases the internal pressure of the battery, affecting its safety and stability. Furthermore, the poor interfacial compatibility between lithium-rich materials and the electrolyte leads to complex chemical reactions at the interface, resulting in gas generation. Simultaneously, charge transfer and ion diffusion at the interface are hindered, further exacerbating capacity decay and accompanying gas production. During the application of lithium-rich materials, gas generation can damage the electrode structure, causing active material to detach, thereby reducing the battery's reversible capacity and cycle life.

[0004] CN118645613A discloses a lithium-rich manganese-based cathode material. The material uses a gradient lithium distribution design to stabilize the lattice oxygen framework, reducing lattice oxygen escape. This not only reduces gas production but also prevents transition metal ion migration and stabilizes the crystal structure, thereby improving cycle stability. The outer layer is coated with a layer of Mn3O4 material with oxygen vacancies, which can trap the oxygen escaping from the outermost layer and suppress irreversible phase transitions during charge and discharge. This also prevents direct contact between the electrolyte and the cathode material, reducing side reactions.

[0005] CN118538880A discloses a lithium-rich manganese-based cathode material and its preparation method. The method involves acid treatment with a weakly acidic organic acid and / or its acidic salt. The organic acid and / or its acidic salt have a weak etching effect on the surface of the matrix powder, which can avoid a significant increase in the specific surface area of ​​the matrix powder, reduce the presence of surface oxygen defects, thereby promoting the effective utilization of the specific capacity of the cathode material, improving the first coulombic efficiency of the cathode material, and improving storage performance and gas generation issues.

[0006] CN118183857A discloses a method for synthesizing lithium-rich manganese-based materials using potassium permanganate decomposition to enhance the oxygen atmosphere. The method includes mixing lithium-rich manganese-based cathode material precursors, lithium carbonate, and potassium permanganate according to a designed ratio; loading the mixed materials into a crucible and firing them in a roller kiln. This method for synthesizing lithium-rich manganese-based materials provides a more favorable oxidizing atmosphere, resulting in better crystallization of the lithium-rich manganese-based materials, particularly Li₂MnO₃ and LiNi. 0.5 Mn 0.5 The solid solution of phases such as O2 and LiNiO2 is more uniform. At the same time, the manganese dioxide formed by the decomposition of potassium permanganate is present in the lithium-rich manganese-based material as a coating layer, which improves the ionic conductivity of the bulk material and improves the material performance.

[0007] Therefore, it is of great significance to provide a lithium-rich material with significantly improved gas production problem and its preparation method. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a composite cathode material with a nano-oxygen permeation layer, its preparation method, and its applications. In the composite cathode material with a nano-oxygen permeation layer provided by the present invention, the nano-oxygen permeation layer diffuses gradient from the surface of the lithium-rich material matrix towards the core, distributing between the grains of the lithium-rich material matrix. Simultaneously, a nanoscale nano-oxygen coating layer is formed on the grain surface, serving as an oxygen-containing layer, which can improve O2 levels. 2- The oxidation barrier reduces the rate of oxygen loss, allowing the active oxygen generated on the surface of lithium-rich materials due to irreversible reactions to be captured by the abundant oxygen vacancies in the nano-oxygen permeation layer, thereby preventing its release as oxygen, reducing gas production, improving the stability of the material, and thus improving the safety and lifespan of the battery.

[0009] To achieve this objective, the present invention employs the following technical solution:

[0010] In a first aspect, the present invention provides a composite cathode material with a nano-oxygen permeation layer, the composite cathode material with a nano-oxygen permeation layer comprising a lithium-rich material matrix and a nano-oxygen permeation layer that diffuses gradient from the surface of the lithium-rich material matrix to the core.

[0011] The material of the oxygen permeation layer includes Li. γ A a B b O 3+1 / 2γ-δ , 0<γ≤2, 0.9≤a≤1, 0.9≤b≤1, 1.8≤a+b≤2, 0.001≤δ≤0.1; the element A includes any one or at least two of La, Ce, Nd, Y, Sr or Pr; the element B includes any one or at least two of Ni, Co, Mn, Cu, Fe, Al, Zr, Nb, Ag, Ti or Ta.

[0012] In this invention, the nano-oxygen permeation layer diffuses gradient from the surface of the lithium-rich material substrate towards the core, distributing between the grains of the lithium-rich material substrate. Simultaneously, a nanoscale nano-oxygen coating layer is formed on the grain surface. The nano-oxygen permeation layer contains Li with a lithium-containing composite perovskite structure. γ A a B b O 3+1 / 2γ-δ In this perovskite structure, the A, B, and O sites are independently missing, forming oxygen vacancies that can accommodate oxygen. These vacancies, acting as an oxygen-accommodating layer, can improve the oxygen content of oxygen. 2- The oxidation barrier is reduced to decrease the rate of oxygen loss, allowing the active oxygen generated on the surface of lithium-rich material grains due to irreversible reactions to be captured by the abundant oxygen vacancies in the nano-oxygen permeation layer. This prevents the release of oxygen, reduces gas production, improves the stability of the material, and ultimately enhances the safety and lifespan of the battery.

[0013] This invention regulates the oxygen vacancy content in a nano-oxygen permeation layer by controlling the stoichiometric ratio of A, B, and O. An appropriate amount of oxygen vacancies can effectively capture reactive oxygen species generated by irreversible surface reactions. However, the oxygen vacancy content in the nano-oxygen permeation layer should not be too high. On the one hand, excessive oxygen vacancies can damage the crystal structure integrity of the nano-oxygen permeation layer, reducing the mechanical strength of the material; on the other hand, too many oxygen vacancies may accelerate the migration of transition metal ions (such as Ni). 2+ / Li + (Mixed arrangement) hinders lithium-ion diffusion, leading to a decrease in reversible capacity; in addition, high concentrations of oxygen vacancies may expose more transition metal active sites, catalyze electrolyte decomposition, accelerate CEI layer thickening, and increase interfacial impedance.

[0014] Preferably, in the composite cathode material with a nano-oxygen permeation layer, the mass percentage of the nano-oxygen permeation layer is 0.1wt% to 3wt%.

[0015] Preferably, the permeation depth of the nano-oxygen permeation layer is 0.5μm to 3μm.

[0016] Preferably, the chemical formula of the lithium-rich material is xLi2MnO3·(1-x)LiMO2, 0<x<1, and the M element includes any one or a combination of at least two of Mn, Ni, Al and Co.

[0017] Preferably, the D50 particle size of the lithium-rich material matrix is ​​2μm~20μm.

[0018] In a second aspect, the present invention provides a method for preparing a composite cathode material having a nano-oxygen permeation layer as described in the first aspect, the method comprising:

[0019] In the dispersion of the lithium-rich material matrix, solutions A, B, and lithium salt solution are introduced in a molar ratio and allowed to react to obtain a composite cathode precursor. The composite cathode precursor is then sintered to prepare the composite cathode material with a nano-oxygen permeation layer.

[0020] This invention employs a wet-method in-situ synthesis strategy to form a nano-oxygen permeation layer in situ within a lithium-rich material matrix, exhibiting a gradient diffusion from the surface to the core. This improves the uniformity and robustness of the nano-oxygen permeation layer. The permeation depth h of the nano-oxygen permeation layer is controllable and is less than 0.5D. 基体 , where D 基体 The D50 particle size represents the lithium-rich material matrix. Utilizing the unique oxygen-permeable properties of the nano-oxygen permeation layer, a gradient permeation layer is formed from the outside in, and a nanoscale nano-oxygen coating layer is formed on the grain surface, improving the surface O2 of the lithium-rich manganese-based grains. 2- The oxidation energy barrier reduces the rate of oxygen loss, allowing the active oxygen generated by irreversible surface reactions to be captured by the abundant oxygen vacancies in the oxygen permeation layer, preventing the release of oxygen and thus reducing gas production.

[0021] Preferably, the solute in solution A includes any one or a combination of at least two of the following: lanthanum nitrate, lanthanum chloride, lanthanum acetate, cerium nitrate, cerium chloride, cerium ammonium nitrate, yttrium nitrate, yttrium chloride, yttrium acetate, strontium nitrate, strontium chloride, strontium acetate, praseodymium nitrate, praseodymium chloride, or praseodymium acetate.

[0022] Preferably, the solute in solution B includes any one or a combination of at least two of the following: nickel nitrate, nickel chloride, nickel acetate, nickel sulfate, cobalt nitrate, cobalt chloride, cobalt acetate, cobalt sulfate, manganese nitrate, manganese chloride, manganese acetate, manganese sulfate, copper nitrate, copper chloride, copper acetate, copper sulfate, ferric nitrate, ferric chloride, ferric acetate, ferric sulfate, aluminum nitrate, aluminum chloride, aluminum sulfate, silver nitrate, zirconium oxychloride, zirconium oxynitrate, ammonium fluoroniobate, ammonium niobate oxalate, titanium oxysulfate, or tantalum pentoxide.

[0023] Preferably, the mass percentage of the lithium-rich material matrix in the dispersion is 25wt% to 75wt%.

[0024] Preferably, the solvent of the dispersion includes water and / or ethanol.

[0025] Preferably, the lithium salt in the lithium salt solution includes any one or a combination of at least two of lithium nitrate, lithium carbonate, lithium chloride, lithium acetate, or lithium citrate.

[0026] Preferably, the reaction temperature is 90℃~100℃.

[0027] Preferably, the reaction is carried out under stirring.

[0028] Preferably, the sintering temperature is 300℃~900℃.

[0029] Preferably, the sintering time is 3h to 8h.

[0030] Preferably, the method for preparing the lithium-rich material matrix includes:

[0031] The cathode material precursor and lithium source are ground and mixed, and then calcined in an oxygen-containing atmosphere to obtain the lithium-rich material matrix.

[0032] Preferably, the calcination temperature is 800℃~1000℃.

[0033] Preferably, the calcination time is 8h to 15h.

[0034] Preferably, the lithium source includes any one or a combination of at least two of lithium nitrate, lithium hydroxide, lithium carbonate, lithium chloride, lithium fluoride, lithium acetate, or lithium citrate.

[0035] Thirdly, the present invention provides a positive electrode sheet, the positive electrode sheet comprising a composite positive electrode material having a nano-oxygen permeation layer as described in the first aspect.

[0036] Fourthly, the present invention provides a lithium-ion battery, the lithium-ion battery comprising a positive electrode as described in the third aspect.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) This invention involves setting a lithium-containing composite perovskite structure in a gradient from the surface to the core of a lithium-rich material matrix. γ A a B b O 3+1 / 2γ-δ The nano-oxygen permeation layer forms a nano-scale nano-oxygen coating on the surface of lithium-rich manganese-based grains. This allows the active oxygen generated on the surface of lithium-rich materials due to irreversible reactions to be captured by the abundant oxygen vacancies in the nano-oxygen permeation layer, effectively reducing gas production, improving material stability, and thus enhancing battery safety and lifespan.

[0039] (2) The present invention adopts a wet permeation in-situ synthesis strategy, which improves the uniformity and firmness of the oxygen permeation layer, and the permeation depth of the oxygen permeation layer is controllable. Attached Figure Description

[0040] Figure 1 It is the 0.3Li2MnO3·0.7LiNi provided in Example 1. 0.5 Mn 0.5 XRD patterns of O2 matrix and composite cathode material with oxygen permeation layer.

[0041] Figure 2 This is the FE-SEM image of the composite cathode material with a nano-oxygen permeation layer provided in Example 1.

[0042] Figure 3 This is an EPMA diagram of the cross-section of the composite cathode material with a nano-oxygen permeation layer provided in Example 1.

[0043] Figure 4 This is an EPMA diagram of the cross-section of the composite cathode material with a nano-oxygen permeation layer provided in Example 5.

[0044] Figure 5 This is an EPMA diagram of the cross-section of the composite cathode material with a nano-oxygen permeation layer provided in Example 7. Detailed Implementation

[0045] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this application; the terms “comprising” and “having” and any variations thereof in this application are intended to cover non-exclusive inclusion.

[0047] In the description of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary or secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0048] In one specific embodiment, the present invention provides a composite cathode material with a nano-oxygen permeation layer, the composite cathode material with a nano-oxygen permeation layer comprising a lithium-rich material matrix and a nano-oxygen permeation layer that diffuses gradient from the surface of the lithium-rich material matrix to the core; the material of the nano-oxygen permeation layer includes Li γ A a B b O 3+1 / 2γ-δWhere 0 < γ ≤ 2, for example, γ can be 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, or 2; 1.8 ≤ a + b ≤ 2, for example, a + b can be 1.8, 1.9, 1.92, 1.94, 1.96, 1.98, or 2; 0.9 ≤ a ≤ 1, for example, a can be 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, or 1; 0.9 ≤ b ≤1, for example, b can be 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99 or 1, 0.001≤δ≤0.1, for example, δ can be 0.001, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1, including but not limited to the listed values, and other unlisted values ​​within the range also apply.

[0049] The element A includes any one or at least two of La, Ce, Nd, Y, Sr or Pr. Typical but non-limiting combinations include combinations of La and Ce, Nd and Y, or Sr and Pr.

[0050] The element B comprises any one or at least two combinations of Ni, Co, Mn, Cu, Fe, Al, Zr, Nb, Ag, Ti, or Ta. Typical but non-limiting combinations include combinations of Ni and Co, Mn and Cu, Fe and Al, Zr and Nb, Ag and Ti, or Ta and Mn.

[0051] In this invention, the nano-oxygen permeation layer diffuses gradient from the surface of the lithium-rich material substrate towards the core, distributing between the grains of the lithium-rich material substrate. Simultaneously, a nanoscale nano-oxygen coating layer is formed on the grain surface. The nano-oxygen permeation layer contains Li with a lithium-containing composite perovskite structure. γ A a B b O 3+1 / 2γ-δ Using it as an oxygen-containing layer can increase the energy barrier to reduce the rate of oxygen loss. This allows the active oxygen generated on the surface of lithium-rich material grains due to irreversible reactions to be captured by the abundant oxygen vacancies in the nano-oxygen permeation layer, thereby preventing its release in the form of oxygen, reducing gas production, improving the stability of the material, and thus improving the safety and lifespan of the battery.

[0052] This invention regulates the oxygen vacancy content in a nano-oxygen permeation layer by controlling the stoichiometric ratio of A, B, and O. An appropriate amount of oxygen vacancies can effectively capture reactive oxygen species generated by irreversible surface reactions. However, the oxygen vacancy content in the nano-oxygen permeation layer should not be too high. On the one hand, excessive oxygen vacancies can damage the crystal structure integrity of the nano-oxygen permeation layer, reducing the mechanical strength of the material; on the other hand, too many oxygen vacancies may accelerate the migration of transition metal ions (such as Ni). 2+ / Li + (Mixed arrangement) hinders lithium-ion diffusion, leading to a decrease in reversible capacity; in addition, high concentrations of oxygen vacancies may expose more transition metal active sites, catalyze electrolyte decomposition, accelerate CEI layer thickening, and increase interfacial impedance.

[0053] In some embodiments, the composite cathode material with a nano-oxygen permeation layer has a nano-oxygen permeation layer with a mass percentage content of 0.1wt% to 3wt%, for example, it can be 0.1wt%, 0.3wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt% or 3wt%, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0054] In some embodiments, the penetration depth of the sodium oxygen permeation layer is 0.5μm to 3μm, for example, it can be 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm or 3μm, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0055] In some embodiments, the chemical formula of the lithium-rich material is xLi2MnO3·(1-x)LiMO2, 0 < x < 1. For example, x can be any of the values ​​listed, and other unlisted values ​​within the range are also applicable. The element M includes any one or at least two of Mn, Ni, Al and Co. Typical but non-limiting combinations include combinations of Mn and Ni, combinations of Ni and Co, combinations of Ni, Co and Mn, and combinations of Ni, Co, Mn and Al.

[0056] In some embodiments, the D50 particle size of the lithium-rich material matrix is ​​2μm to 20μm, for example, it can be 2μm, 4μm, 6μm, 8μm, 10μm, 12μm, 14μm, 16μm, 18μm or 20μm, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0057] In another specific embodiment, the present invention provides a method for preparing a composite cathode material with a nano-oxygen permeation layer as described in the foregoing specific embodiment, the preparation method comprising:

[0058] In the dispersion of the lithium-rich material matrix, solutions A, B, and lithium salt solution are introduced in a molar ratio and allowed to react to obtain a composite cathode precursor. The composite cathode precursor is then sintered to prepare the composite cathode material with a nano-oxygen permeation layer.

[0059] This invention employs a wet-method in-situ synthesis strategy to form a nano-oxygen permeation layer in situ within a lithium-rich material matrix, exhibiting a gradient diffusion from the surface to the core. This improves the uniformity and robustness of the nano-oxygen permeation layer. The permeation depth h of the nano-oxygen permeation layer is controllable and is less than 0.5D. 基体 , where D 基体 The D50 particle size represents the lithium-rich material matrix. Utilizing the unique oxygen-permeable properties of the nano-oxygen permeation layer, a gradient permeation layer is formed from the outside in, and a nanoscale nano-oxygen coating layer is formed on the grain surface, improving the surface O2 of the lithium-rich manganese-based grains. 2- The oxidation energy barrier reduces the rate of oxygen loss, allowing the active oxygen generated by irreversible surface reactions to be captured by the abundant oxygen vacancies in the oxygen permeation layer, preventing the release of oxygen and thus reducing gas production.

[0060] In some embodiments, the solute of solution A includes any one or a combination of at least two of lanthanum nitrate, lanthanum chloride, lanthanum acetate, cerium nitrate, cerium chloride, cerium ammonium nitrate, yttrium nitrate, yttrium chloride, yttrium acetate, strontium nitrate, strontium chloride, strontium acetate, praseodymium nitrate, praseodymium chloride, or praseodymium acetate. Typical but non-limiting combinations include combinations of lanthanum nitrate and lanthanum chloride, combinations of lanthanum acetate and cerium nitrate, combinations of cerium chloride and cerium ammonium nitrate, combinations of yttrium nitrate and yttrium chloride, combinations of yttrium acetate and strontium nitrate, combinations of strontium chloride and strontium acetate, combinations of praseodymium nitrate and praseodymium chloride, or combinations of praseodymium acetate and cerium nitrate.

[0061] In some embodiments, the solute of solution B includes any one or a combination of at least two of the following: nickel nitrate, nickel chloride, nickel acetate, nickel sulfate, cobalt nitrate, cobalt chloride, cobalt acetate, cobalt sulfate, manganese nitrate, manganese chloride, manganese acetate, manganese sulfate, copper nitrate, copper chloride, copper acetate, copper sulfate, ferric nitrate, ferric chloride, ferric acetate, ferric sulfate, aluminum nitrate, aluminum chloride, aluminum sulfate, silver nitrate, zirconium oxychloride, zirconium oxynitrate, ammonium fluoroniobate, ammonium niobate oxalate, titanium oxysulfate, or tantalum pentoxide. Typical but non-limiting combinations include combinations of nickel nitrate and nickel chloride, nickel acetate and nickel sulfate, cobalt nitrate and cobalt chloride, cobalt acetate and cobalt sulfate, manganese nitrate and manganese chloride, manganese acetate and manganese sulfate, copper nitrate and copper chloride, copper acetate and copper sulfate, ferric nitrate and ferric chloride, ferric acetate and ferric sulfate, aluminum nitrate and aluminum chloride, and aluminum sulfate and silver nitrate.

[0062] In some embodiments, the mass percentage of the lithium-rich material matrix in the dispersion is 25wt% to 75wt%, for example, it can be 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, or 75wt%, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0063] In some embodiments, the solvent of the dispersion includes water and / or ethanol.

[0064] In some embodiments, the lithium salt in the lithium salt solution includes any one or a combination of at least two of lithium nitrate, lithium hydroxide, lithium carbonate, lithium chloride, lithium acetate, or lithium citrate. Typical but non-limiting combinations include combinations of lithium nitrate and lithium carbonate, combinations of lithium chloride and lithium acetate, or combinations of lithium citrate and lithium hydroxide.

[0065] In some embodiments, the reaction temperature is 90°C to 100°C, for example, it can be 90°C, 92°C, 94°C, 96°C, 98°C or 100°C, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0066] In some embodiments, the reaction is carried out under stirring. In this invention, the stirring time is not specifically limited; stirring is stopped when the solvent has completely evaporated.

[0067] In some embodiments, the preparation method further includes drying the composite cathode precursor at a temperature of 100°C to 120°C, such as 100°C, 105°C, 110°C, 115°C or 120°C, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0068] In some embodiments, the sintering temperature is 300℃~900℃, for example, it can be 300℃, 400℃, 500℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃ or 900℃, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0069] In some embodiments, the sintering time is 3h to 8h, for example, it can be 3h, 4h, 5h, 6h, 7h or 8h, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0070] In some embodiments, the method for preparing the lithium-rich material matrix includes:

[0071] The cathode material precursor and lithium source are ground and mixed, and then calcined in an oxygen-containing atmosphere to obtain the lithium-rich material matrix.

[0072] In some embodiments, the calcination temperature is 800℃~1000℃, for example, it can be 800℃, 850℃, 900℃, 950℃ or 1000℃, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0073] In some embodiments, the calcination time is 8h to 15h, for example, it can be 8h, 9h, 10h, 11h, 12h, 13h, 14h or 15h, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0074] In some embodiments, the lithium source includes any one or a combination of at least two of lithium nitrate, lithium carbonate, lithium chloride, lithium fluoride, lithium acetate, or lithium citrate. Typical but non-limiting combinations include combinations of lithium nitrate and lithium carbonate, combinations of lithium chloride and lithium fluoride, or combinations of lithium acetate and lithium citrate.

[0075] In yet another embodiment, the present invention provides a positive electrode sheet comprising a composite positive electrode material having a nano-oxygen permeation layer as described in the preceding embodiment.

[0076] In yet another embodiment, the present invention provides a lithium-ion battery comprising a positive electrode as described in yet another embodiment above.

[0077] Example 1

[0078] This embodiment provides a composite cathode material with a nano-oxygen permeation layer, wherein the composite cathode material with the nano-oxygen permeation layer comprises 0.3Li₂MnO₃·0.7LiNi 0.5 Mn 0.5 An O2 substrate and a nano-oxygen permeation layer that diffuses gradient from the surface of a lithium-rich material substrate to the core; the nano-oxygen permeation layer is made of Li2LaCoO. 3.95 The composite cathode material has a sodium oxygen permeation layer with a mass percentage of 1 wt% and a permeation depth of 1.5 μm.

[0079] The preparation method of the composite cathode material includes:

[0080] (1) Preparation of 0.3Li₂MnO₃·0.7LiNi 0.5 Mn 0.5 O2 matrix: Mn prepared by co-precipitation method 0.65 Ni 0.35(OH)₂ was thoroughly ground and mixed with lithium hydroxide, and then calcined at 880℃ for 12 h in air to prepare 0.3Li₂MnO₃·0.7LiNi₂ with a D50 particle size of 6 μm. 0.5 Mn 0.5 O2 matrix;

[0081] (2) The 0.3Li2MnO3·0.7LiNi prepared in step (1) 0.5 Mn 0.5 O2 matrix dispersed in water yields 0.3Li2MnO3·0.7LiNi 0.5 Mn 0.5 A dispersion with an O2 matrix content of 50 wt%, according to Li2LaCoO 3.95 The composition is 0.3Li₂MnO₃·0.7LiNi. 0.5 Mn 0.5 1 wt% of the O2 matrix and the stoichiometric ratio were added to the dispersion in parallel with lanthanum nitrate solution, cobalt nitrate solution and lithium nitrate solution. The mixture was stirred at 95°C until the solvent was completely evaporated, and dried at 110°C to obtain the composite cathode precursor. The composite cathode material with the nano-oxygen permeation layer was prepared by sintering at 800°C for 5 h.

[0082] The 0.3Li2MnO3·0.7LiNi provided in this embodiment 0.5 Mn 0.5 XRD patterns of O2 matrix and composite cathode materials with oxygen permeation layer are as follows: Figure 1 As shown, compared to 0.3Li2MnO3·0.7LiNi 0.5 Mn 0.5 No impurity peaks were observed in the XRD pattern of the O2-based composite cathode material with a nano-oxygen permeation layer. The surface of this material was found to be composed of 0.3Li2MnO3·0.7LiNi... 0.5 Mn 0.5 After setting a sodium oxygen permeation layer on the O2 substrate surface, Li was not treated. 1.3 Ni 0.35 Mn 0.65 O 2.3 The structure of the matrix itself has an impact.

[0083] Further, the 0.3Li2MnO3·0.7LiNi provided in this embodiment... 0.5 Mn 0.5 Field emission scanning electron microscopy (FE-SEM) was used to test the O2 matrix and the composite cathode material with a sodium oxygen permeation layer. Figure 2 As shown, the composite cathode material with a nano-oxygen permeation layer prepared by this invention has high sphericity.

[0084] The cross-section of the prepared composite cathode material with a nano-oxygen permeation layer was tested using an electron probe X-ray microscopy (EPMA) system. The test results are as follows: Figure 3 As shown in the figure, it can be seen that Li2LaCoO 3.95 The sodium oxygen permeation layer permeated into 0.3Li₂MnO₃·0.7LiNi 0.5 Mn 0.5 The penetration depth is approximately 1.5 μm inside the O2 matrix.

[0085] Example 2

[0086] This embodiment provides a composite cathode material with a nano-oxygen permeation layer, wherein the composite cathode material with the nano-oxygen permeation layer comprises 0.45Li₂MnO₃·0.55LiNi 0.27 Co 0.46 Mn 0.27 An O2 substrate and a nano-oxygen permeation layer that diffuses gradient from the surface of a lithium-rich material substrate to the core; the nano-oxygen permeation layer is made of Li. 1.5 La 0.9 NiO 3.749 The composite cathode material with a nano-oxygen permeation layer has a nano-oxygen permeation layer with a mass percentage content of 1 wt% and a permeation depth of 1.5 μm.

[0087] The preparation method of the composite cathode material with a nano-oxygen permeation layer includes:

[0088] (1) Preparation of 0.45Li2MnO3·0.55LiNi 0.27 Co 0.46 Mn 0.27 O2 matrix: Mn prepared by co-precipitation method 0.6 Ni 0.15 Co 0.25 (OH)₂ was thoroughly ground and mixed with lithium hydroxide, and then calcined at 800℃ for 8 hours in air to prepare 0.45Li₂MnO₃·0.55LiNi₂ with a D50 particle size of 5 μm. 0.27 Co 0.46 Mn 0.27 O2 matrix;

[0089] (2) The 0.45Li2MnO3·0.55LiNi prepared in step (1) 0.27 Co 0.46 Mn 0.27 An O2 matrix was dispersed in ethanol to obtain 0.45Li2MnO3·0.55LiNi 0.27 Co 0.46 Mn 0.27 A dispersion with an O2 matrix content of 25 wt%, according to Li1.5 La 0.9 NiO 3.749 The composition is 0.45Li₂MnO₃·0.55LiNi. 0.27 Co 0.46 Mn 0.27 1 wt% of the O2 matrix and the stoichiometric ratio were added to the dispersion in parallel with lanthanum nitrate solution, nickel nitrate solution and lithium acetate solution. The mixture was stirred at 90°C until the solvent was completely evaporated, and dried at 120°C to obtain the composite cathode precursor. The composite cathode material with the nano-oxygen permeation layer was prepared by sintering at 600°C for 3 hours.

[0090] Example 3

[0091] This embodiment provides a composite cathode material with a nano-oxygen permeation layer, wherein the composite cathode material with the nano-oxygen permeation layer comprises 0.2Li2MnO3·0.8LiNi 0.31 Co 0.38 Mn 0.31 An O2 substrate and a nano-oxygen permeation layer that diffuses gradient from the surface of a lithium-rich material substrate to the core; the nano-oxygen permeation layer is made of LiCeNi. 0.9 O 3.45 The composite cathode material with a nano-oxygen permeation layer has a nano-oxygen permeation layer with a mass percentage content of 1 wt% and a permeation depth of 1.5 μm.

[0092] The preparation method of the composite cathode material with a nano-oxygen permeation layer includes:

[0093] (1) Preparation of 0.2Li2MnO3·0.8LiNi 0.31 Co 0.38 Mn 0.31 O2 matrix: Mn prepared by co-precipitation method 0.45 Ni 0.25 Co 0.3 Lithium hydroxide (OH)₂ was thoroughly ground and mixed, and then calcined at 1000℃ for 15 h in air to prepare Li₂ with a D50 particle size of 6 μm. 1.2 Ni 0.25 Co 0.3 Mn 0.45 O 2.2 Matrix;

[0094] (2) The 0.2Li2MnO3·0.8LiNi prepared in step (1) 0.31 Co 0.38 Mn 0.31 O2 matrix dispersed in ethanol yields 0.2Li2MnO3·0.8LiNi 0.31 Co 0.38 Mn 0.31A dispersion with an O2 matrix content of 75 wt%, according to LiCeNi 0.9 O 3.45 The composition is 0.2Li₂MnO₃·0.8LiNi. 0.31 Co 0.38 Mn 0.31 1 wt% of the O2 matrix and the stoichiometric ratio were added to the dispersion in parallel with cerium nitrate solution, nickel nitrate solution and lithium nitrate solution. The mixture was stirred at 100°C until the solvent was completely evaporated, and dried at 110°C to obtain the composite cathode precursor. The composite cathode material with the nano-oxygen permeation layer was prepared by sintering at 900°C for 8 hours.

[0095] Example 4

[0096] This embodiment provides a composite cathode material with a nano-oxygen permeation layer, wherein the composite cathode material with the nano-oxygen permeation layer is made of Li, except that the material of the nano-oxygen permeation layer is Li. 0.2 La 0.9 Co 0.9 O 3.15 Except for the above, everything else is the same as in Example 1.

[0097] The preparation method, except according to Li 0.2 La 0.9 Co 0.9 O 3.15 Except for adjusting the molar ratio of lanthanum nitrate, cobalt nitrate and lithium nitrate, everything else was the same as in Example 1.

[0098] Example 5

[0099] This embodiment provides a composite cathode material with a nano-oxygen permeation layer. Except that the mass percentage of the nano-oxygen permeation layer in the composite cathode material with the nano-oxygen permeation layer is 0.5 wt%, everything else is the same as in Embodiment 1.

[0100] The cross-section of the prepared composite cathode material with a nano-oxygen permeation layer was tested using an electron probe X-ray microscopy (EPMA) system. The test results are as follows: Figure 4 As shown in the figure, it can be seen that Li2LaCoO 3.95 The sodium oxygen permeation layer permeated into 0.3Li₂MnO₃·0.7LiNi 0.5 Mn 0.5 The penetration depth inside the O2 matrix is ​​0.7 μm.

[0101] The preparation method, except for adjusting the pumping rates of lanthanum nitrate, cobalt nitrate, and nitric acid to Li₂LaCoO₃, involves adjusting the amounts of these substances into the desired concentration. 3.95 Except for the mass percentage content being 0.5wt%, everything else is the same as in Example 1.

[0102] Example 6

[0103] This embodiment provides a composite cathode material with a nano-oxygen permeation layer, except for Li2LaCoO in the composite cathode material with the nano-oxygen permeation layer. 3.95 Except for the mass percentage content of 3wt% and the permeation depth of the sodium oxygen permeation layer being 2.6μm, everything else is the same as in Example 1.

[0104] The preparation method, except for adjusting the pumping rates of lanthanum nitrate, cobalt nitrate, and nitric acid to Li₂LaCoO₃, involves adjusting the amounts of these substances into the desired concentration. 3.95 Except for the mass percentage content of 3wt%, it is the same as in Example 1.

[0105] Example 7

[0106] This embodiment provides a composite cathode material with a nano-oxygen permeation layer, except for Li2LaCoO in the composite cathode material with the nano-oxygen permeation layer. 3.95 Except for the mass percentage of 4wt%, it is the same as in Example 1.

[0107] The cross-section of the prepared composite cathode material with a nano-oxygen permeation layer was tested using an electron probe X-ray microscopy (EPMA) system. The test results are as follows: Figure 5 As shown in the figure, it can be seen that Li2LaCoO 3.95 The sodium oxygen permeation layer permeated into 0.3Li₂MnO₃·0.7LiNi 0.5 Mn 0.5 The penetration depth is 3μm inside the O2 matrix, which means it penetrates to the core of the lithium-rich material matrix.

[0108] The preparation method, except for adjusting the pumping rates of lanthanum nitrate, cobalt nitrate, and nitric acid to Li₂LaCoO₃, involves adjusting the amounts of these substances into the desired concentration. 3.95 Except for the mass percentage of 4wt%, it is the same as in Example 1.

[0109] Example 8

[0110] This embodiment provides a composite cathode material with a nano-oxygen permeation layer. Except for the sintering temperature of the composite cathode precursor in step (2) being 200°C during the preparation process, all other aspects are the same as in Example 1.

[0111] In this embodiment, the permeation depth of the nano-oxygen permeation layer in the composite cathode material with the nano-oxygen permeation layer is 0.6 μm.

[0112] Example 9

[0113] This embodiment provides a composite cathode material with a nano-oxygen permeation layer. Except for the temperature of sintering the composite cathode precursor in step (2) of the preparation process being 1000℃, the rest is the same as in embodiment 1.

[0114] In this embodiment, the permeation depth of the nano-oxygen permeation layer in the composite cathode material with the nano-oxygen permeation layer is 1.7 μm.

[0115] Example 10

[0116] This embodiment provides a composite cathode material with a nano-oxygen permeation layer, wherein the composite cathode material with the nano-oxygen permeation layer comprises 0.3Li₂MnO₃·0.7LiNi 0.5 Mn 0.5 An O2 substrate and a nano-oxygen permeation layer that diffuses in a gradient from the surface of a lithium-rich material substrate to the core; the nano-oxygen permeation layer is made of Li2LaCoO. 3.95 The penetration depth of the oxygen permeable layer is 0.1 μm.

[0117] The preparation method of the composite cathode material with a nano-oxygen permeation layer includes:

[0118] (1) Preparation of 0.3Li₂MnO₃·0.7LiNi 0.5 Mn 0.5 O2 matrix: Same as in Example 1;

[0119] (2) According to Li2LaCoO 3.95 The composition is 0.3Li₂MnO₃·0.7LiNi. 0.5 Mn 0.5 A mixed solution of lanthanum nitrate, cobalt nitrate, and lithium nitrate was prepared with an O2 matrix content of 1 wt%, and 0.3Li2MnO3·0.7LiNi was added. 0.5 Mn 0.5 The O2 matrix is ​​dispersed in a mixed solution, stirred at 95°C until the solvent is completely evaporated, and dried at 110°C to obtain a composite cathode precursor; sintered at 800°C for 5 hours to prepare the composite cathode material with a nano-oxygen permeation layer.

[0120] Example 11

[0121] This embodiment provides a composite cathode material with a nano-oxygen permeation layer, wherein the composite cathode material with the nano-oxygen permeation layer comprises 0.3Li₂MnO₃·0.7LiNi 0.5 Mn 0.5 O2 matrix and coating of 0.3Li2MnO3·0.7LiNi 0.5 Mn 0.5 A nano-oxygen permeation layer on the surface of an O2 substrate; the material of the nano-oxygen permeation layer is Li2LaCoO. 3.95 The penetration depth of the oxygen permeable layer is 0.5 μm.

[0122] The preparation method of the composite cathode material includes:

[0123] (1) Preparation of 0.3Li₂MnO₃·0.7LiNi 0.5 Mn 0.5 O2 matrix: Same as in Example 1;

[0124] (2) According to Li2LaCoO 3.95 The composition is 0.3Li₂MnO₃·0.7LiNi. 0.5 Mn 0.5 Weigh 1 wt% of the O2 matrix, including lanthanum nitrate, cobalt nitrate, and lithium nitrate, and mix with 0.3Li2MnO3·0.7LiNi 0.5 Mn 0.5 The O2 matrix was ball-milled for 5 hours to obtain a composite cathode precursor; the composite cathode material with a nano-oxygen permeation layer was prepared by sintering at 800℃ for 5 hours.

[0125] Comparative Example 1

[0126] This comparative example provides a lithium-rich material with the chemical formula 0.3Li₂MnO₃·0.7LiNi. 0.5 Mn 0.5 O2, the preparation method of the lithium-rich material is the same as that in Example 1 except that step (2) is not performed.

[0127] Comparative Example 2

[0128] This comparative example provides a composite cathode material with a nano-oxygen permeation layer. Except for replacing the material of the nano-oxygen permeation layer with Li2LaCoO4, the composite cathode material with the nano-oxygen permeation layer is the same as that in Example 1.

[0129] The preparation method is the same as in Example 1, except that the molar ratio of lanthanum nitrate, cobalt nitrate and lithium nitrate is adjusted according to Li2LaCoO4.

[0130] Comparative Example 3

[0131] This comparative example provides a composite cathode material with a nano-oxygen permeation layer, wherein the material of the nano-oxygen permeation layer is Li₂LaCoO₂. 3.88 Except for the above, everything else is the same as in Example 1.

[0132] The preparation method, except for Li2LaCoO 3.88 Except for adjusting the molar ratio of lanthanum nitrate, cobalt nitrate and lithium nitrate, everything else was the same as in Example 1.

[0133] Comparative Example 4

[0134] This comparative example provides a composite cathode material with a nano-oxygen permeation layer, wherein the nano-oxygen permeation layer is made of Li₂La.0.85 CoO 3.95 Except for the above, everything else is the same as in Example 1.

[0135] The preparation method, except for Li2La 0.85 CoO 3.95 Except for adjusting the molar ratio of lanthanum nitrate, cobalt nitrate and lithium nitrate, everything else was the same as in Example 1.

[0136] Comparative Example 5

[0137] This comparative example provides a composite cathode material with a nano-oxygen permeation layer, wherein the composite cathode material with the nano-oxygen permeation layer is made of Li₂La, except that the nano-oxygen permeation layer is made of Li₂La. 0.85 Co 0.85 O 3.95 Except for the above, everything else is the same as in Example 1.

[0138] The preparation method, except for Li2La 0.85 Co 0.85 O 3.95 Except for adjusting the molar ratio of lanthanum nitrate, cobalt nitrate and lithium nitrate, everything else was the same as in Example 1.

[0139] Performance testing:

[0140] (1) Testing the first-cycle coulombic efficiency and 50-cycle capacity retention: The positive electrode materials provided in all the above examples and comparative examples were dispersed in NMP with conductive carbon black and PVDF at a mass ratio of 92:4:4 to prepare a positive electrode slurry with a solid content of 45%. The slurry was coated on the surface of aluminum foil and dried to obtain a positive electrode sheet. A coin cell was prepared using a lithium sheet as the negative electrode. Then, under a voltage range of 2.0V-4.55V, a 0.1C rate charge and discharge was performed to test the charging capacity and discharging capacity of the first cycle. The first-cycle coulombic efficiency was calculated, and the capacity retention rate was tested under 0.33C charge and discharge conditions at 25℃ for 50 cycles. The test results are shown in Table 1.

[0141] (2) Testing the 0.33C discharge specific capacity and the volume growth rate after 28 days of storage at 60℃: The cathode materials provided in all the above examples and comparative examples were dispersed in NMP with SP, CNTs and PVDF at a mass ratio of 95:2:1:2 to obtain a cathode slurry with a solid content of 60%, which was coated on the surface of aluminum foil to obtain a compaction density of 2.5 g / cm³. 3 Surface density 10.5 g / cm³ 2Using lithium metal as the negative electrode and an N / P ratio of 1.09, a 1Ah capacity wound cell was fabricated. The specific capacity of the prepared cell was tested at a discharge rate of 0.33C within a voltage range of 2.0V-4.5V. The cell was then fully charged at 0.33C, and its volume V1 was measured. The cell was then stored at 60℃ for 28 days, and its volume V2 was measured. The volume expansion rate of the cell was calculated as δV = (V2 - V1) / V2. The test results are shown in Table 1.

[0142] Table 1

[0143]

[0144] Based on the test results in Table 1, this invention provides a lithium-containing perovskite structure nano-oxygen permeation layer on the surface of a lithium-rich material substrate, which diffuses gradient from the surface to the core. This is achieved by controlling the Li... γ A a B b O 3+1 / 2γ-δ The stoichiometric ratio of A, B, and O in the sodium oxygen permeation layer is used to regulate the content of oxygen vacancies, effectively capturing reactive oxygen generated by irreversible surface reactions, thereby preventing its release in the form of oxygen, reducing gas production, improving the stability of the material, and thus improving the safety and lifespan of the battery.

[0145] According to the test results of Example 1, Comparative Example 1, and Comparative Example 2, if no oxygen permeation layer is provided, or only a lithium-containing perovskite structure permeation layer with no oxygen vacancies is provided, it is impossible to effectively capture the active oxygen generated on the surface of lithium-rich materials due to irreversible reactions, resulting in increased gas production. After storage at 60°C for 28 days, the volume expansion rate of the battery increases significantly, and the cycle capacity retention rate decreases significantly.

[0146] Based on the test results of Example 1 and Comparative Examples 3 to 5, if Li γ A a B b O 3+1 / 2γ-δ Excessive vacancies formed by A, B, or O in the CEI layer will disrupt the crystal structure integrity of the oxygen permeation layer, reduce the mechanical strength of the material, accelerate the migration of transition metal ions (such as Ni²⁺ / Li⁺ mixing), hinder lithium ion diffusion, and lead to a decrease in reversible capacity. At the same time, high concentrations of oxygen vacancies may expose more transition metal active sites, catalyze electrolyte decomposition, accelerate the thickening of the CEI layer, and increase interfacial impedance, all of which lead to a decrease in the cycling performance of the material.

[0147] Based on the test results of Examples 1 and 7, if the composite cathode material with a nano-oxygen permeation layer contains Li2LaCoO 3.95 An excessively high percentage of La will lead to reduced capacity, and excessive La will also... 3+ Blocking Li +The diffusion channel weakens the kinetics.

[0148] Based on the test results of Examples 1, 8, and 9, both excessively high and excessively low sintering temperatures of the composite cathode precursor are detrimental to performance improvement. If the sintering temperature is too low, Li2LaCoO... 3.95 Limited growth and incomplete crystal structure development result in an amorphous permeation layer with shallow penetration depth and poor uniformity. Furthermore, the nanoscale nano-oxygen coating formed on the grain surface exhibits poor uniformity and is easily dissolved during cycling. Additionally, excessively low sintering temperatures lead to high oxygen vacancy formation barriers and low oxygen vacancy concentrations, resulting in insufficient ability of the nano-oxygen permeation layer to capture reactive oxygen species and effectively suppress oxygen release. Conversely, excessively high sintering temperatures cause over-reaction between the nano-oxygen permeation layer and the substrate material, potentially forming non-uniform blocky coatings that hinder lithium-ion diffusion and may even lead to La... 3+ Excessive diffusion into the matrix lattice leads to increased cation mixing and deteriorates performance. At the same time, excessively high sintering temperature may promote excessive oxygen vacancy generation, resulting in excessive oxygen vacancy content and causing structural defects.

[0149] Based on the test results of Examples 1 and 10, if 0.3Li2MnO3·0.7LiNi is not first prepared... 0.5 Mn 0.5 The O2 matrix is ​​dispersed in water and then circulated into lanthanum nitrate solution, cobalt nitrate solution, and lithium nitrate solution. Instead, 0.3Li2MnO3·0.7LiNi is directly added. 0.5 Mn 0.5 The O2 matrix is ​​dispersed in a mixed solution of lanthanum nitrate, cobalt nitrate, and lithium nitrate. In this mixed solution, the competitive adsorption of metal salts leads to local concentration gradients, resulting in island-like agglomerations that prevent the formation of a gradient penetration layer and nanoscale uniform coating on the grain surface. Furthermore, the difference in co-precipitation rates between La / Co / Li (La³⁺ > Co²⁺ > Li⁺) causes an imbalance in elemental distribution, leading to surface elemental segregation and preventing the complete formation of Li₂LaCoO according to the stoichiometric ratio. 3.95 This leads to a decrease in ionic conductivity.

[0150] Based on the test results of Examples 1 and 11, if lanthanum nitrate, cobalt nitrate, and lithium nitrate are coated onto 0.3Li2MnO3·0.7LiNi in a solid phase manner... 0.5 Mn 0.5 On the surface of the O2 matrix, solid particles cannot penetrate the pores of the secondary particles in the matrix, thus failing to form a sodium-oxygen permeation layer. Furthermore, cracks easily form after sintering, and electrolyte permeation increases side reactions. Additionally, the non-uniform contact between solid particles prevents complete conversion to Li2LaCoO during sintering. 3.95 And Li2LaCoO 3.95The formation of an inactive phase (e.g., La2NiO4) between the layer and the substrate leads to a 3-5 fold increase in interfacial charge transfer impedance.

[0151] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A composite cathode material with a nano-oxygen permeation layer, characterized in that, The composite cathode material with a nano-oxygen permeation layer includes a lithium-rich material matrix and a nano-oxygen permeation layer that diffuses gradient from the surface of the lithium-rich material matrix to the core. The material of the oxygen permeation layer includes Li. γ A a B b O 3+1 / 2γ-δ , 0<γ≤2, 0.9≤a≤1, 0.9≤b≤1, 1.8≤a+b≤2, 0.001≤δ≤0.1; The element A includes La and / or Ce; The B element contains Ni and / or Co.

2. The composite cathode material with a nano-oxygen permeation layer as described in claim 1, characterized in that, In the composite cathode material, the mass percentage of the oxygen permeation layer is 0.1wt%~3wt%; And / or, the penetration depth of the sodium oxygen permeation layer is 0.5μm~3μm.

3. A method for preparing a composite cathode material with a nano-oxygen permeation layer as described in claim 1 or 2, characterized in that, The preparation method includes: In the dispersion of the lithium-rich material matrix, solutions A, B, and lithium salt solution are introduced in a molar ratio and allowed to react to obtain a composite cathode precursor. The composite cathode precursor is then sintered to prepare the composite cathode material with a nano-oxygen permeation layer.

4. The preparation method according to claim 3, characterized in that, The solute in solution A includes any one or a combination of at least two of lanthanum nitrate, lanthanum chloride, lanthanum acetate, cerium nitrate, cerium chloride, or cerium ammonium nitrate. And / or, the solute in solution B includes any one or a combination of at least two of nickel nitrate, nickel chloride, nickel acetate, nickel sulfate, cobalt nitrate, cobalt chloride, cobalt acetate, or cobalt sulfate.

5. The preparation method according to claim 3, characterized in that, The dispersion contains 25wt% to 75wt% lithium-rich material matrix by mass.

6. The preparation method according to claim 4, characterized in that, The reaction temperature is 90℃~100℃; And / or, the reaction is carried out under stirring; And / or, the sintering temperature is 300℃~900℃; And / or, the sintering time is 3h~8h.

7. The preparation method according to claim 4, characterized in that, The method for preparing the lithium-rich material matrix includes: The cathode material precursor and lithium source are ground and mixed, and then calcined in an oxygen-containing atmosphere to obtain the lithium-rich material matrix.

8. The preparation method according to claim 7, characterized in that, The calcination temperature is 800℃~1000℃; And / or, the calcination time is 8h~15h.

9. A positive electrode plate, characterized in that, The positive electrode sheet includes the composite positive electrode material with a nano-oxygen permeation layer as described in claim 1 or 2.

10. A lithium-ion battery, characterized in that, The lithium-ion battery includes the positive electrode as described in claim 9.

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