A perovskite-coated modified lithium-rich manganese-based positive electrode material, a preparation method and a battery

Abstract

The present application relates to a kind of perovskite coating modification lithium-rich manganese-based positive electrode material, preparation method, battery, the perovskite coating modification lithium-rich manganese-based positive electrode material includes lithium-rich manganese-based inner core and YMnO3 coating layer coated in the lithium-rich manganese-based inner core;The YMnO3 coating layer is the coating layer of oxygen vacancy introduction.This application is by the use of YMnO3 coating layer and the introduction of oxygen vacancy, form oxygen defect, inhibit oxygen loss;Oxygen vacancy can also promote lithium ion diffusion, while inhibiting the disproportionation reaction of Mn 3+ , reduce the manganese dissolution.Therefore, the perovskite coating modification lithium-rich manganese-based positive electrode material provided in the present application has higher cycle stability under high voltage conditions.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to a lithium-rich manganese-based cathode material, particularly a perovskite-coated modified lithium-rich manganese-based cathode material, its preparation method, and a battery. Background Technology

[0002] The rapid development of the electric vehicle industry has placed increasingly higher demands on the safety, energy density, and cycle life of lithium-ion batteries. Lithium-rich manganese-based cathode materials are considered next-generation lithium battery materials due to their high specific capacity and high operating voltage. However, their industrialization faces three major drawbacks: first, the oxygen release problem—when charged above 4.5V, lattice oxygen in the Li2MnO3 phase undergoes irreversible extraction, resulting in an initial efficiency of less than 80%, and the released oxygen exacerbates electrolyte decomposition; second, the manganese dissolution problem—Mn... 3+ A disproportionation reaction occurs in the electrolyte, and the dissolved Mn 2+ Migration to the negative electrode damages the SEI film, and the manganese dissolution rate after 7 days of storage at 60℃ is generally above 10%; thirdly, there is the problem of voltage decay. During the charge and discharge cycle, the layered structure gradually transforms into the spinel phase, and the voltage decay is above 0.5mV per cycle.

[0003] To address the aforementioned shortcomings of lithium-rich manganese-based cathode materials, current mainstream solutions include bulk doping and surface coating. Bulk doping stabilizes the crystal structure by introducing foreign elements, but the doping effect of most elements is limited and selectively sensitive, making it difficult to completely unify oxygen release and manganese dissolution. For example, CN115513449A and CN117712339A employ high-entropy cation doping (such as Al, Ti, Mg, etc.), which can enhance the bonding strength between transition metals and oxygen, but the effects of different elements vary significantly; for instance, Al doping can improve cycle stability, but elements such as Ti and Zr have a significant inhibitory effect on oxygen release.

[0004] The purpose of surface coating is to isolate electrolyte corrosion, but there are problems with coating uniformity and interface compatibility. CN118553911A discloses that traditional solid-phase coating is prone to forming "island-like coatings", and discontinuous areas are still exposed to the electrolyte, resulting in local manganese dissolution and oxygen release. Usually, a coating amount of more than 5 wt% is required to be effective, but a high coating amount will sacrifice specific capacity and hinder lithium-ion diffusion; uniform coating requires high-cost processes and is difficult to scale up.

[0005] Therefore, developing new modification strategies to comprehensively improve the electrochemical performance of lithium-rich manganese-based cathode materials is an urgent technical problem to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a perovskite-coated modified lithium-rich manganese-based cathode material, its preparation method, and a battery. The perovskite-coated modified lithium-rich manganese-based cathode material utilizes a YMnO3 coating layer and introduces oxygen vacancies to create oxygen defects, thereby suppressing oxygen loss. These oxygen vacancies also promote lithium-ion diffusion while inhibiting MnO2 diffusion. 3+ The disproportionation reaction reduces manganese dissolution. Therefore, the perovskite-coated modified lithium-rich manganese-based cathode material provided by this invention exhibits high cycle stability under high voltage conditions.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a perovskite-coated modified lithium-rich manganese-based cathode material, wherein the perovskite-coated modified lithium-rich manganese-based cathode material comprises a lithium-rich manganese-based core and a YMnO3 coating layer coating the lithium-rich manganese-based core.

[0009] The YMnO3 coating layer is a coating layer that introduces oxygen vacancies.

[0010] This invention utilizes a YMnO3 coating layer and introduces oxygen vacancies to create oxygen defects, thereby inhibiting oxygen loss. These oxygen vacancies also promote lithium-ion diffusion while suppressing Mn... 3+ The disproportionation reaction reduces manganese dissolution. Therefore, the perovskite-coated modified lithium-rich manganese-based cathode material provided by this invention exhibits high cycle stability under high voltage conditions.

[0011] Secondly, this invention provides a method for preparing a perovskite-coated modified lithium-rich manganese-based cathode material, the method comprising:

[0012] (1) The lithium-rich manganese precursor material is mixed with the lithium source, and the first sintering is performed to obtain the lithium-rich manganese-based cathode material;

[0013] (2) The lithium-rich manganese-based cathode material is immersed in a yttrium-containing solution, spray-dried and then pre-calcined to form a Y2O3-coated lithium-rich manganese-based cathode material; the second sintering yields a perovskite-type YMnO3-coated lithium-rich manganese-based cathode material.

[0014] (3) The perovskite-type YMnO3-coated lithium-rich manganese-based cathode material is annealed in a reducing atmosphere to introduce oxygen vacancies into the YMnO3 coating layer, thereby obtaining the perovskite-coated modified lithium-rich manganese-based cathode material described in the first aspect.

[0015] This invention is the first to coat the surface of a lithium-rich manganese-based cathode material with a perovskite-type YMnO3 coating layer that introduces oxygen vacancies. Unlike traditional inert coatings that block direct contact between the material and the electrolyte, the perovskite-type YMnO3 coating layer with introduced oxygen vacancies can also participate in charge compensation and suppress Mn. 3+The disproportionation reaction simultaneously blocks electrolyte erosion, captures lattice oxygen, blocks manganese dissolution, and enhances Li + The diffusion coefficient and other functions enhance the structural stability and cycle performance of lithium-rich manganese-based materials under high voltage conditions. Moreover, the synthesis temperature of the perovskite-type YMnO3 coating layer with introduced oxygen vacancies is consistent with the lithiation sintering temperature range of the lithium-rich manganese-based cathode material. During the preparation process, the bulk lithiation and the in-situ construction of the surface coating layer can be achieved simultaneously, enhancing the interface stability. Finally, the perovskite-type YMnO3 coating layer with introduced oxygen vacancies allows for a wide range of oxygen vacancy concentrations. By changing the annealing conditions, lithium-rich manganese-based cathode materials with different oxygen vacancy concentrations can be obtained to meet different voltage requirements.

[0016] In some embodiments of the present invention, the lithium-rich manganese precursor material in step (1) includes manganese and transition metal elements; the transition metal elements include Ni and / or Co.

[0017] In some embodiments of the present invention, the lithium source in step (1) includes any one or at least two of lithium carbonate, lithium hydroxide or lithium acetate. Typical but non-limiting combinations include combinations of lithium carbonate and lithium hydroxide, combinations of lithium hydroxide and lithium acetate, combinations of lithium carbonate and lithium acetate, or combinations of lithium carbonate, lithium hydroxide and lithium acetate.

[0018] In some embodiments of the present invention, the median particle size D50 of the lithium-rich manganese precursor material in step (1) is 4μm to 12μm, for example, it can be 4μm, 5μm, 6μm, 8μm, 10μm or 12μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] In some embodiments of the present invention, the molar ratio of the lithium-rich manganese precursor material to lithium in the lithium source in step (1) is 1:1.2 to 1:1.6, for example, it can be 1.2, 1.3, 1.4, 1.5 or 1.6, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] The lithium-rich manganese precursor materials in this invention include hydroxide precursor materials, carbonate precursor materials, or precursor materials prepared by the sol-gel method, etc., which are all conventional lithium-rich manganese-based precursor material types that can be paired with a lithium source. This invention applies to all of them.

[0021] In some embodiments of the present invention, step (1) the first sintering includes: first heating to 400℃~600℃ (e.g., 400℃, 450℃, 500℃, 550℃, or 600℃) at a heating rate of 3℃ / min~6℃ / min (e.g., 3℃ / min, 4℃ / min, 5℃ / min, or 6℃ / min, etc.) and holding at that temperature for 3h~7h (3h, 4h, 5h, 6h, or 7h, etc.), and then heating at a rate of 2℃ / min~5℃ / min (e.g., 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, or 6℃ / min, etc.) and holding at that temperature for 3h~7h (3h, 4h, 5h, 6h, or 7h, etc.). The temperature is increased to 800℃~1000℃ (e.g., 800℃, 850℃, 900℃, 950℃, or 1000℃) at a heating rate of ℃ / min, 4℃ / min, or 5℃ / min, and then held at that temperature for 8h~20h (e.g., 8h, 10h, 12h, 15h, 18h, or 20h). Finally, the temperature is reduced to room temperature at a cooling rate of 4℃ / min~8℃ / min (e.g., 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, or 8℃ / min).

[0022] In some embodiments of the present invention, the yttrium-containing solution in step (2) includes an ethanol solution of yttrium nitrate, wherein the concentration of yttrium nitrate is 2wt% to 8wt%, for example, it can be 2wt%, 4wt%, 5wt%, 6wt% or 8wt%, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0023] In some embodiments of the present invention, the solid-liquid ratio of the impregnation in step (2) is 1:5 to 1:10, for example, it can be 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable. The unit of the solid-liquid ratio is g / mL.

[0024] In some embodiments of the present invention, the inlet temperature of the spray drying in step (2) is 150°C to 200°C, for example, it can be 150°C, 160°C, 180°C, 190°C or 200°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] In some embodiments of the present invention, the outlet temperature of the spray drying in step (2) is 60°C to 90°C, for example, it can be 60°C, 70°C, 80°C or 90°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] In some embodiments of the present invention, the pre-firing temperature in step (2) is 400°C to 600°C, for example, it can be 400°C, 450°C, 500°C, 550°C or 600°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] In some embodiments of the present invention, the pre-burning time in step (2) is 3h to 6h, for example, it can be 3h, 4h, 5h or 6h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] In some embodiments of the present invention, the temperature of the second sintering in step (2) is 880°C to 980°C, for example, it can be 880°C, 900°C, 920°C, 950°C, 960°C or 980°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] In some embodiments of the present invention, the second sintering time in step (2) is 2h to 8h, for example, it can be 2h, 3h, 4h, 5h, 6h or 8h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] In some embodiments of the present invention, the reducing atmosphere gas used in step (3) is an argon-hydrogen mixture, wherein the volume percentage of hydrogen in the argon-hydrogen mixture is 3% to 10%, for example, it can be 3%, 4%, 5%, 6%, 8% or 10%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] In some embodiments of the present invention, the annealing temperature in step (3) is 550°C to 650°C, for example, it can be 550°C, 580°C, 600°C, 620°C or 650°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] In some embodiments of the present invention, the annealing time in step (3) is 2h to 5h, for example, it can be 2h, 3h, 4h or 5h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] As a preferred embodiment of the preparation method provided in the second aspect, the preparation method includes:

[0034] (1) Lithium-rich manganese precursor materials (Ni 0.4 Mn 0.6 (OH)2) is mixed with lithium carbonate, first heated to 400℃~600℃ at a heating rate of 3℃ / min~6℃ / min and held for 3h~7h, then heated to 800℃~1000℃ at a heating rate of 2℃ / min~5℃ / min and held for 8h~20h, and finally cooled to room temperature at a cooling rate of 4℃ / min~8℃ / min to obtain lithium-rich manganese-based cathode material;

[0035] The median particle size D50 of lithium-rich manganese precursor materials is 4 μm to 12 μm;

[0036] The molar ratio of lithium in the lithium-rich manganese precursor material to lithium in lithium carbonate is 1:1.2 to 1:1.6.

[0037] (2) The lithium-rich manganese-based cathode material is immersed in an ethanol solution of yttrium nitrate (the concentration of yttrium nitrate is 2wt%~8wt%), spray-dried, and then pre-calcined at 400℃~600℃ for 3h~6h to form a Y2O3-coated lithium-rich manganese-based cathode material; sintered at 880℃~980℃ for 2h~8h to obtain a perovskite-type YMnO3-coated lithium-rich manganese-based cathode material.

[0038] The solid-liquid ratio of the impregnation is 1:5 to 1:10, and the unit of the solid-liquid ratio is g / mL;

[0039] The inlet temperature of the spray dryer is 150℃~200℃, and the outlet temperature is 60℃~90℃.

[0040] (3) The perovskite-type YMnO3-coated lithium-rich manganese-based cathode material is annealed at 550℃~650℃ for 2h~5h in a reducing atmosphere to introduce oxygen vacancies into the YMnO3 coating layer, thereby obtaining the perovskite-coated modified lithium-rich manganese-based cathode material described in the first aspect.

[0041] The reducing atmosphere is an argon-hydrogen mixture, in which hydrogen accounts for 3% to 10% of the volume.

[0042] Thirdly, the present invention provides a battery comprising the perovskite-coated modified lithium-rich manganese-based cathode material described in the first aspect, or the perovskite-coated modified lithium-rich manganese-based cathode material prepared by the preparation method described in the second aspect.

[0043] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) This invention uses a YMnO3 coating layer and introduces oxygen vacancies to form oxygen defects and inhibit oxygen loss; oxygen vacancies can also promote lithium-ion diffusion and inhibit Mn 3+ The disproportionation reaction reduces manganese dissolution. Therefore, the perovskite-coated modified lithium-rich manganese-based cathode material provided by this invention exhibits high cycle stability under high voltage conditions;

[0046] (2) This invention is the first to coat the surface of a lithium-rich manganese-based cathode material with a perovskite-type YMnO3 coating layer that introduces oxygen vacancies. Unlike traditional inert coatings that block direct contact between the material and the electrolyte, the perovskite-type YMnO3 coating layer that introduces oxygen vacancies can also participate in charge compensation and suppress Mn. 3+ The disproportionation reaction simultaneously blocks electrolyte erosion, captures lattice oxygen, blocks manganese dissolution, and enhances Li + The diffusion coefficient and other functions enhance the structural stability and cycle performance of lithium-rich manganese-based materials under high voltage conditions. Moreover, the synthesis temperature of the perovskite-type YMnO3 coating layer with introduced oxygen vacancies is consistent with the lithiation sintering temperature range of the lithium-rich manganese-based cathode material. During the preparation process, the bulk lithiation and the in-situ construction of the surface coating layer can be achieved simultaneously, enhancing the interface stability. Finally, the perovskite-type YMnO3 coating layer with introduced oxygen vacancies allows for a wide range of oxygen vacancy concentrations. By changing the annealing conditions, lithium-rich manganese-based cathode materials with different oxygen vacancy concentrations can be obtained to meet different voltage requirements. Detailed Implementation

[0047] 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.

[0048] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0049] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0050] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0051] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0052] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0053] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0054] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0055] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0056] In this invention, "optional" means that something is optional, that is, it refers to any one of the two parallel solutions of "having" or "not having". If there are multiple "optional" options in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "optional" option is independent.

[0057] In this invention, "room temperature" generally refers to 4℃~35℃, and can refer to 20℃±5℃. In some embodiments of this invention, room temperature refers to 20℃~30℃, preferably 25℃.

[0058] Example 1

[0059] This embodiment provides a method for preparing a perovskite-coated modified lithium-rich manganese-based cathode material, the preparation method comprising:

[0060] (1) Lithium-rich manganese precursor materials (Ni 0.4 Mn 0.6 (OH)2) was mixed with lithium carbonate, first heated to 500℃ at a heating rate of 5℃ / min and held for 5h, then heated to 900℃ at a heating rate of 4℃ / min and held for 10h, and finally cooled to room temperature at a cooling rate of 6℃ / min to obtain lithium-rich manganese-based cathode material.

[0061] The median particle size D50 of the lithium-rich manganese precursor material is 8 μm;

[0062] The molar ratio of lithium in the lithium-rich manganese precursor material to lithium carbonate is 1:1.4.

[0063] (2) The lithium-rich manganese-based cathode material is immersed in an ethanol solution of yttrium nitrate (the concentration of yttrium nitrate is 3wt%), spray-dried, and then pre-calcined at 500°C for 4 hours to form a Y2O3-coated lithium-rich manganese-based cathode material; sintered at 920°C for 4 hours to obtain a perovskite-type YMnO3-coated lithium-rich manganese-based cathode material.

[0064] The solid-liquid ratio of the impregnation is 1:8, and the unit of the solid-liquid ratio is g / mL;

[0065] The spray dryer has an inlet temperature of 180°C and an outlet temperature of 80°C.

[0066] (3) The perovskite-type YMnO3-coated lithium-rich manganese-based cathode material is annealed at 600°C for 3 hours in a reducing atmosphere to introduce oxygen vacancies into the YMnO3 coating layer, thereby obtaining the perovskite-coated modified lithium-rich manganese-based cathode material.

[0067] The reducing atmosphere is an argon-hydrogen mixture, in which hydrogen accounts for 5% of the volume.

[0068] Example 2

[0069] This embodiment provides a method for preparing a perovskite-coated modified lithium-rich manganese-based cathode material, the preparation method comprising:

[0070] (1) Lithium-rich manganese precursor materials (Ni 0.4 Mn 0.6 (OH)2) was mixed with lithium carbonate, first heated to 400℃ at a heating rate of 3℃ / min and held for 7h, then heated to 800℃ at a heating rate of 2℃ / min and held for 20h, and finally cooled to room temperature at a cooling rate of 4℃ / min to obtain lithium-rich manganese-based cathode material.

[0071] The median particle size D50 of the lithium-rich manganese precursor material is 4 μm;

[0072] The molar ratio of lithium in the lithium-rich manganese precursor material to lithium in lithium carbonate is 1:1.2;

[0073] (2) The lithium-rich manganese-based cathode material is immersed in an ethanol solution of yttrium nitrate (the concentration of yttrium nitrate is 2wt%), spray-dried, and then pre-calcined at 400°C for 6 hours to form a Y2O3-coated lithium-rich manganese-based cathode material; it is then sintered at 880°C for 8 hours to obtain a perovskite-type YMnO3-coated lithium-rich manganese-based cathode material.

[0074] The solid-liquid ratio of the impregnation is 1:5, and the unit of the solid-liquid ratio is g / mL;

[0075] The spray dryer has an inlet temperature of 150°C and an outlet temperature of 60°C.

[0076] (3) The perovskite-type YMnO3-coated lithium-rich manganese-based cathode material is annealed at 550°C for 5 hours in a reducing atmosphere to introduce oxygen vacancies into the YMnO3 coating layer, thereby obtaining the perovskite-coated modified lithium-rich manganese-based cathode material.

[0077] The reducing atmosphere is a mixture of argon and hydrogen, in which hydrogen accounts for 3% of the volume.

[0078] Example 3

[0079] This embodiment provides a method for preparing a perovskite-coated modified lithium-rich manganese-based cathode material, the preparation method comprising:

[0080] (1) Lithium-rich manganese precursor materials (Ni 0.4 Mn 0.6 (OH)2) was mixed with lithium carbonate, first heated to 600℃ at a heating rate of 6℃ / min and held for 3h, then heated to 1000℃ at a heating rate of 5℃ / min and held for 8h, and finally cooled to room temperature at a cooling rate of 8℃ / min to obtain lithium-rich manganese-based cathode material.

[0081] The median particle size D50 of the lithium-rich manganese precursor material is 12 μm;

[0082] The molar ratio of lithium in the lithium-rich manganese precursor material to lithium in lithium carbonate is 1:1.6.

[0083] (2) The lithium-rich manganese-based cathode material is immersed in an ethanol solution of yttrium nitrate (the concentration of yttrium nitrate is 8wt%), spray-dried, and then pre-calcined at 600°C for 3h to form a Y2O3-coated lithium-rich manganese-based cathode material; sintered at 980°C for 2h to obtain a perovskite-type YMnO3-coated lithium-rich manganese-based cathode material.

[0084] The solid-liquid ratio of the impregnation is 1:10, and the unit of the solid-liquid ratio is g / mL;

[0085] The spray dryer has an inlet temperature of 200°C and an outlet temperature of 90°C.

[0086] (3) The perovskite-type YMnO3-coated lithium-rich manganese-based cathode material is annealed at 650°C for 2 hours in a reducing atmosphere to introduce oxygen vacancies into the YMnO3 coating layer, thereby obtaining the perovskite-coated modified lithium-rich manganese-based cathode material.

[0087] The reducing atmosphere is a mixture of argon and hydrogen, in which hydrogen accounts for 10% of the volume.

[0088] Example 4

[0089] This embodiment provides a method for preparing a perovskite-coated modified lithium-rich manganese-based cathode material. Except for the concentration of yttrium nitrate in the ethanol solution of yttrium nitrate being 1 wt%, the rest is the same as in Example 1.

[0090] Example 5

[0091] This embodiment provides a method for preparing a perovskite-coated modified lithium-rich manganese-based cathode material. Except for the concentration of yttrium nitrate in the ethanol solution of yttrium nitrate being 10 wt%, the rest is the same as in Example 1.

[0092] Example 6

[0093] This embodiment provides a method for preparing a perovskite-coated modified lithium-rich manganese-based cathode material. Except for the volume percentage of hydrogen in the argon-hydrogen mixture being 1%, the rest is the same as in Example 1.

[0094] Example 7

[0095] This embodiment provides a method for preparing a perovskite-coated modified lithium-rich manganese-based cathode material. Except for the volume percentage of hydrogen in the argon-hydrogen mixture being 12 wt%, the rest is the same as in Example 1.

[0096] Comparative Example 1

[0097] This comparative example provides a lithium-rich manganese-based cathode material obtained in step (1) of Example 1.

[0098] Comparative Example 2

[0099] This comparative example provides a perovskite-coated modified lithium-rich manganese-based cathode material, which is identical to Example 1 except that it was not annealed in a reducing atmosphere.

[0100] Performance Characterization

[0101] The perovskite-coated modified lithium-rich manganese-based cathode material or lithium-rich manganese-based cathode material provided in the above examples and comparative examples were weighed with conductive agent (acetylene black) and binder (polyvinylidene fluoride) at a mass ratio of 8:1:1, and dissolved in N-methylpyrrolidone and mixed evenly to obtain a slurry; then the slurry was coated on aluminum foil and dried in a vacuum drying oven at 80°C for 8 hours; the aluminum foil was then stamped into 1.13 cm pieces. 2 The positive electrode is obtained by taking a circular piece of material; a lithium metal sheet is used as the counter electrode, and a polyethylene film (Celgard 2400) is used as the separator. The two are then assembled into a CR2032 button cell in an argon glove box.

[0102] Using the Blue Electric CT2001A battery testing system, cycle performance tests were conducted at rates of 0.1C and 0.33C in the voltage range of 2.5V to 4.55V, with 100 cycles per test. The results are shown in Table 1.

[0103] Table 1

[0104]

[0105] As can be seen from Examples 1 to 3 in Table 1, the preparation method provided by the present invention enables the modified lithium-rich manganese-based cathode material to exhibit the best discharge specific capacity and cycle stability, with a 0.1C discharge specific capacity exceeding 262mAh / g and a capacity retention rate of up to 98.75% after 100 cycles.

[0106] A comparison of Examples 1 with Examples 4 and 5 shows that if the concentration of yttrium nitrate is too low, the YMnO3 coating layer will not form sufficiently, and it will not be able to effectively block electrolyte erosion and capture lattice oxygen; if the concentration is too high, the coating layer will be too thick, hindering lithium ion diffusion. Therefore, the concentration of yttrium nitrate needs to be controlled within a reasonable range to ensure the modification effect.

[0107] A comparison of Example 1 with Examples 6 and 7 shows that the hydrogen volume ratio is too low, the reduction degree is insufficient, and the number of oxygen vacancies is too small, making it difficult to fully promote lithium-ion diffusion and inhibit Mn. 3+ Disproportionation reaction; if the proportion is too high, it will lead to excessive reduction, destroy the integrity of the perovskite structure, and increase the dissolution of manganese; therefore, the rationality of the hydrogen volume ratio in the reducing atmosphere directly affects the oxygen vacancy concentration.

[0108] A comparison of Comparative Examples 1 and 2 with Example 1 shows that the synergistic effect of the YMnO3 coating layer and oxygen vacancies is key to improving material performance. Comparative Example 1, without coating or oxygen vacancy introduction, suffers from severe lattice oxygen loss and significant manganese dissolution, resulting in a cycle retention rate of only about 86%. Comparative Example 2, with only YMnO3 coating but no oxygen vacancies, can partially block electrolyte contact but cannot achieve charge compensation and Li... + Despite improved diffusion, the performance was still significantly lower than in Example 1, demonstrating that the introduction of oxygen vacancies is the core of achieving multifunctional synergy.

[0109] In summary, this invention utilizes a YMnO3 coating layer and introduces oxygen vacancies to create oxygen defects, thereby suppressing oxygen loss. These oxygen vacancies also promote lithium-ion diffusion while inhibiting Mn... 3+ The disproportionation reaction is reduced, thus minimizing manganese dissolution. Therefore, the perovskite-coated modified lithium-rich manganese-based cathode material provided by this invention exhibits high cycle stability under high voltage conditions. This invention is the first to coat the surface of a lithium-rich manganese-based cathode material with a perovskite-type YMnO3 coating layer introducing oxygen vacancies. Unlike traditional inert coatings that block direct contact between the material and the electrolyte, the perovskite-type YMnO3 coating layer introducing oxygen vacancies can also participate in charge compensation and inhibit Mn dissolution. 3+The disproportionation reaction simultaneously blocks electrolyte erosion, captures lattice oxygen, blocks manganese dissolution, and enhances Li + The diffusion coefficient and other functions enhance the structural stability and cycle performance of lithium-rich manganese-based materials under high voltage conditions. Moreover, the synthesis temperature of the perovskite-type YMnO3 coating layer with introduced oxygen vacancies is consistent with the lithiation sintering temperature range of the lithium-rich manganese-based cathode material. During the preparation process, the bulk lithiation and the in-situ construction of the surface coating layer can be achieved simultaneously, enhancing the interface stability. Finally, the perovskite-type YMnO3 coating layer with introduced oxygen vacancies allows for a wide range of oxygen vacancy concentrations. By changing the annealing conditions, lithium-rich manganese-based cathode materials with different oxygen vacancy concentrations can be obtained to meet different voltage requirements.

[0110] 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 perovskite-coated modified lithium-rich manganese-based cathode material, characterized in that, The perovskite-coated modified lithium-rich manganese-based cathode material includes a lithium-rich manganese-based core and a YMnO3 coating layer coating the lithium-rich manganese-based core. The YMnO3 coating layer is a coating layer that introduces oxygen vacancies; The perovskite-coated modified lithium-rich manganese-based cathode material was prepared using the following method: (1) The lithium-rich manganese precursor material is mixed with the lithium source, and the first sintering is performed to obtain the lithium-rich manganese-based cathode material; (2) The lithium-rich manganese-based cathode material is immersed in a yttrium-containing solution, spray-dried and then pre-calcined to form a Y2O3-coated lithium-rich manganese-based cathode material; the second sintering yields a perovskite-type YMnO3-coated lithium-rich manganese-based cathode material. (3) The perovskite-type YMnO3-coated lithium-rich manganese-based cathode material is annealed in a reducing atmosphere to introduce oxygen vacancies into the YMnO3 coating layer, thereby obtaining the perovskite-coated modified lithium-rich manganese-based cathode material.

2. A method for preparing a perovskite-coated modified lithium-rich manganese-based cathode material, characterized in that, The preparation method includes: (1) The lithium-rich manganese precursor material is mixed with the lithium source, and the first sintering is performed to obtain the lithium-rich manganese-based cathode material; (2) The lithium-rich manganese-based cathode material is immersed in a yttrium-containing solution, spray-dried and then pre-calcined to form a Y2O3-coated lithium-rich manganese-based cathode material; the second sintering yields a perovskite-type YMnO3-coated lithium-rich manganese-based cathode material. (3) The perovskite-type YMnO3-coated lithium-rich manganese-based cathode material is annealed in a reducing atmosphere to introduce oxygen vacancies into the YMnO3 coating layer, thereby obtaining the perovskite-coated modified lithium-rich manganese-based cathode material as described in claim 1.

3. The preparation method according to claim 2, characterized in that, The lithium-rich manganese precursor material in step (1) includes manganese and transition metal elements; The transition metal elements include Ni and / or Co; And / or, the lithium source in step (1) includes any one or a combination of at least two of lithium carbonate, lithium hydroxide or lithium acetate.

4. The preparation method according to claim 2 or 3, characterized in that, The median particle size D50 of the lithium-rich manganese precursor material in step (1) is 4 μm to 12 μm; And / or, the molar ratio of the lithium-rich manganese precursor material to lithium in the lithium source in step (1) is 1:1.2 to 1:1.

6.

5. The preparation method according to claim 2, characterized in that, Step (1) The first sintering includes: first heating to 400℃~600℃ at a heating rate of 3℃ / min~6℃ / min and holding for 3h~7h, then heating to 800℃~1000℃ at a heating rate of 2℃ / min~5℃ / min and holding for 8h~20h, and finally cooling to room temperature at a cooling rate of 4℃ / min~8℃ / min.

6. The preparation method according to claim 2, characterized in that, The yttrium-containing solution in step (2) includes an ethanolic solution of yttrium nitrate, wherein the concentration of yttrium nitrate is 2wt%~8wt%. And / or, the solid-liquid ratio of the impregnation in step (2) is 1:5 to 1:10, and the unit of the solid-liquid ratio is g / mL.

7. The preparation method according to claim 2, characterized in that, The inlet temperature of the spray dryer in step (2) is 150℃~200℃; And / or, the outlet temperature of the spray dryer in step (2) is 60°C to 90°C; And / or, the pre-firing temperature in step (2) is 400℃~600℃; And / or, the pre-burning time in step (2) is 3h~6h.

8. The preparation method according to claim 2, characterized in that, In step (2), the second sintering temperature is 880℃~980℃; And / or, the second sintering time in step (2) is 2h~8h.

9. The preparation method according to claim 2, characterized in that, The reducing atmosphere used in step (3) is an argon-hydrogen mixture, in which the volume percentage of hydrogen is 3% to 10%. And / or, the annealing temperature in step (3) is 550℃~650℃; And / or, the annealing time in step (3) is 2h~5h.

10. A battery, characterized in that, The battery comprises the perovskite-coated modified lithium-rich manganese-based cathode material according to claim 1, or the perovskite-coated modified lithium-rich manganese-based cathode material prepared by the preparation method according to any one of claims 2 to 9.

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