Coated lithium-rich manganese-based positive electrode material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of new energy, and particularly relates to a coated lithium-rich manganese-based positive electrode material as well as a preparation method and application thereof. The preparation method comprises the following steps: S1, mixing an acrylamide polymer and a metal coating agent, and performing spray drying to obtain a mixture; and S2, coating the surface of the lithium-rich manganese-based positive electrode material with the mixture, and sintering to obtain the coated lithium-rich manganese-based positive electrode material. The coated lithium-rich manganese-based positive electrode material provided by the invention has high capacity, high magnification and high cycle performance.

Description

Technical Field

[0001] This invention belongs to the field of new energy technology, specifically relating to a coated lithium-rich manganese-based cathode material, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries are widely used in portable electronic devices, electric vehicles, electric vertical takeoff and landing (EVTOL) aircraft, marine propulsion, and large-scale energy storage systems due to their high energy density and long cycle life. However, existing cobalt-containing cathode materials suffer from high cost, insufficient capacity, and poor cycle stability at high voltages. Therefore, research on cobalt-free cathode materials has attracted much attention. Among them, manganese-based materials stand out due to their low cost and non-toxicity, especially manganese-rich layered oxides (LRMOs), which have become strong candidates for next-generation lithium-ion battery cathode materials with a reversible specific capacity of approximately 280 mAh / g and excellent energy density. However, the absence of cobalt leads to sluggish LRMO kinetics, and lithium-rich manganese-based materials are prone to transition metal (such as Mn) formation during cycling. 2+ Dissolution leads to the destruction of the positive electrode lattice structure, which in turn causes rapid capacity decay and a decline in cycle performance. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the defects of existing lithium-rich manganese-based cathode materials, such as low capacity, poor rate performance and poor cycle stability, and thus provide a coated lithium-rich manganese-based cathode material, its preparation method and application.

[0004] Therefore, the present invention provides the following technical solution: The first aspect of this invention protects a method for preparing a lithium-rich manganese-based cathode material, wherein the preparation method includes the following steps: S1, an acrylamide polymer and a metal coating agent are mixed and then spray-dried to obtain a mixture; S2, the mixture is coated onto the surface of the lithium-rich manganese-based cathode material and sintered to obtain the coated lithium-rich manganese-based cathode material.

[0005] In some alternative embodiments, the acrylamide polymer includes at least one of polyacrylamide, acrylamide / acrylic acid copolymer, and acrylamide / acrylate copolymer.

[0006] In some alternative embodiments, the acrylamide polymer has a weight-average molecular weight of 10,000 to 20,000,000.

[0007] In some alternative embodiments, the acrylamide polymer is polyacrylamide.

[0008] In some alternative embodiments, the acrylamide polymer has a weight-average molecular weight of 200,000 to 10,000,000.

[0009] In some alternative embodiments, the acrylamide polymer is used in a percentage of 3-6 wt% and the metal coating agent is used in a percentage of 0.001-0.01 wt%, based on the lithium-rich manganese-based cathode material.

[0010] In some alternative embodiments, the acrylamide polymer is used in an amount of 4.8-5 wt% and the metal coating agent is used in an amount of 0.002-0.01 wt%, based on the lithium-rich manganese-based cathode material.

[0011] In some optional embodiments, the average particle size of the acrylamide polymer is 0.1 nm-10 μm, optionally 0.1-100 nm, and further optionally 30-50 nm.

[0012] In some optional embodiments, the average particle size of the metal coating agent is 0.1 nm-5 μm, optionally 5-50 nm, or optionally 10-30 nm.

[0013] In this invention, a dynamic light scattering (DLS) instrument was used to test the particle size of acrylamide polymers and metal coating agents.

[0014] In some alternative embodiments, the metal coating agent includes at least one of a metal oxide and its precursor, a metal carbonate and its precursor.

[0015] In this invention, the precursor of metal oxide refers to a substance capable of generating metal oxide, and the specific form is not limited. Therefore, the raw materials are abundant. Typically, without limitation, manganese oxide is used as an example. Manganese sulfate solution and sodium carbonate solution are prepared, and polyacrylamide is mixed with manganese sulfate solution and sodium carbonate solution and spray dried.

[0016] In some alternative embodiments, the metal oxide includes at least one of manganese oxide, silicon oxide, and titanium oxide.

[0017] In some alternative embodiments, the metal carbonate includes at least one of manganese carbonate, strontium carbonate, tungsten carbonate, and yttrium carbonate.

[0018] In some optional embodiments, the spray drying conditions include: a pressure of 0.1-0.8 MPa, an inlet air temperature of 100-300°C, and an outlet air temperature of 50-100°C.

[0019] In some optional embodiments, the spray drying conditions include: a pressure of 0.2-0.7 MPa, an inlet air temperature of 120-250°C, and an outlet air temperature of 60-80°C.

[0020] In some alternative embodiments, the sintering conditions include: heating to 500-600°C at a heating rate of 1-5°C and sintering for 5-8 hours.

[0021] In some alternative embodiments, the sintering conditions include sintering at 550-580°C.

[0022] In some optional embodiments, the general formula of the lithium-rich manganese-based cathode material is Li. x Ni a Co b Mn c O2, where 1≤x≤1.2, 0.10≤a≤0.30, 0≤b≤0.15, and 0.50≤c≤0.60.

[0023] In this invention, the molar ratio of Ni to Mn or the molar ratio of Ni to Co to Mn is limited according to actual needs and there is no fixed ratio.

[0024] A second aspect of this invention protects a lithium-rich manganese-based cathode material prepared by the aforementioned preparation method.

[0025] A third aspect of this invention protects a secondary battery, wherein the secondary battery comprises the aforementioned coated lithium-rich manganese-based cathode material.

[0026] The technical solution of this invention has the following advantages: 1. This invention provides a method for preparing a lithium-rich manganese-based cathode material. Acrylamide polymers possess good dispersibility and flexibility. The metal coating agent and the acrylamide polymer work synergistically to form a uniformly dispersed mixture, resulting in more uniform coating and ensuring a tighter adhesion of the coating layer on the surface of the lithium-rich manganese-based cathode material. This effectively isolates the cathode material from direct contact with the electrolyte, inhibits the decomposition reaction of the electrolyte under high voltage, and reduces the generation of byproducts. Simultaneously, the polymer carbonizes during sintering, forming an organic-inorganic composite layer with both flexibility and conductivity. The residual carbon enhances the electronic conductivity of the coating layer, reduces interfacial impedance, and avoids capacity loss. The metal coating agent has good lattice matching with the surface of the lithium-rich manganese-based cathode material, and can stabilize the transition metal on the cathode material surface through chemical bonding, inhibiting its dissolution. This results in a material with high capacity, high rate capability, and high cycle performance.

[0027] 2. When the acrylamide polymer of this invention is polyacrylamide, the surface is neutral, no additional charge is introduced, and side reactions are avoided; compared with copolymers, it has better flexibility and more uniform coating.

[0028] 3. The specific weight-average molecular weight of the acrylamide polymer of the present invention can further control its film-forming ability, thereby making the coating more uniform and affecting the electrical properties.

[0029] 4. The specific conditions of spray drying in this invention can further precisely control the drying path of droplets, forming an organic-inorganic composite layer that combines flexibility and conductivity, thereby further improving electrical performance.

[0030] 5. The specific sintering conditions of this invention can further regulate the phase transformation and stability of the coating layer, so that the formed coating layer can block side reactions while retaining unobstructed lithium-ion transport channels, ensuring high capacity and further improving electrical performance. Detailed Implementation

[0031] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0032] 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 the application; the terms “comprising” and “having” and any variations thereof in the text of this application are intended to cover non-exclusive inclusion.

[0033] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0034] The "range" disclosed in this application is defined by 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. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers from a to b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter can be, for example, integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0035] In the description of the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0036] In the description of the embodiments of this application, the term "at least one" refers to one or more (including two).

[0037] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0038] The company acquired lithium-rich manganese-based cathode materials from GEM Co., Ltd. Polyacrylamide-1: Polymerization is carried out using acrylamide aqueous solution as raw material, monomer concentration of 28wt%, reaction temperature of 70℃, and ammonium persulfate as initiator. The mass ratio of initiator to monomer is 0.45%:1, the polymerization time is 18h, the polymerized block is cut and mechanically granulated into granules, then dried in a fluidized bed to remove moisture, the dried granules are ground by a grinder and then screened by a sieve. Polyacrylamide-2: Polymerization is carried out using acrylamide aqueous solution as raw material, monomer concentration of 25wt%, reaction temperature of 25℃, and ammonium persulfate as initiator. The mass ratio of initiator to monomer is 0.35%:1, the polymerization time is 13h, the polymerized block is cut and mechanically granulated into granules, then dried in a fluidized bed to remove moisture, the dried granules are ground by a grinder and then screened by a sieve. Polyacrylamide-3: Polymerization is carried out using acrylamide aqueous solution as raw material, monomer concentration of 23wt%, reaction temperature of 65℃, and ammonium persulfate as initiator. The mass ratio of initiator to monomer is 0.25%:1, the polymerization time is 8h, the polymerized block is cut and mechanically granulated into granules, then dried in a fluidized bed to remove moisture, the dried granules are ground by a grinder and then screened by a sieve. Polyacrylamide-4: Polymerization is carried out using acrylamide aqueous solution as raw material, monomer concentration of 20wt%, reaction temperature of 60℃, and ammonium persulfate as initiator. The mass ratio of initiator to monomer is 0.10%:1, the polymerization time is 5h, the polymerized block is cut and mechanically granulated into granules, then dried in a fluidized bed to remove moisture, the dried granules are ground by a grinder and then screened by a sieve. Acrylamide / acrylic acid copolymer: The concentration of the acrylamide aqueous solution is 20wt%, the concentration of the acrylic acid aqueous solution is 40wt%, and the initiator ammonium persulfate is added. The mass ratio of acrylamide, acrylic acid and ammonium persulfate is 1:3:0.10%. The reaction temperature is 70℃ and the polymerization time is 5h. The polymerized granules are cut and mechanically granulated into particles, and then dried in a fluidized bed to remove moisture. The dried particles are then ground by a grinder and screened by a sieve.

[0039] Example 1 This embodiment provides a method for preparing a lithium-rich manganese-based cathode material, including the following steps: S1, mix polyacrylamide-1, a 1 mol / L manganese sulfate solution and a 1 mol / L sodium carbonate solution, and spray dry them at a pressure of 0.5 MPa, an inlet air temperature of 180℃ and an outlet air temperature of 90℃. S2, in lithium-rich manganese-based cathode material Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 The O2 surface-coated mixture, based on the mass of the lithium-rich manganese-based cathode material, contains 5 wt% polyacrylamide-1 and 0.002 wt% manganese carbonate. The weight-average molecular weight of polyacrylamide-1 is 8.5 million, the average particle size is 30 nm, and the average particle size of manganese carbonate is 50 nm. The mixture is heated to 550 °C at a heating rate of 3 °C and sintered for 6 h to obtain the lithium-rich manganese-based cathode material.

[0040] Example 2 This embodiment provides a method for preparing a lithium-rich manganese-based cathode material, including the following steps: S1, mix polyacrylamide-2 and solid manganese carbonate, and spray dry at a pressure of 0.6 MPa, an inlet air temperature of 200℃, and an outlet air temperature of 70℃; S2, in lithium-rich manganese-based cathode material Li 1.2 Ni 0.2 Mn 0.60 The surface-coated mixture of O2, based on the mass of lithium-rich manganese-based cathode material, contains 3 wt% polyacrylamide-2 and 0.0035 wt% manganese carbonate. The weight-average molecular weight of polyacrylamide-2 is 5.5 million, the average particle size is 40 nm, and the average particle size of manganese carbonate is 50 nm. The mixture is heated to 600 °C at a heating rate of 3 °C and sintered for 6 h to obtain the coated lithium-rich manganese-based cathode material.

[0041] Example 3 This embodiment provides a method for preparing a lithium-rich manganese-based cathode material, including the following steps: S1, mix polyacrylamide-3 and solid manganese carbonate, and spray dry at a pressure of 0.7 MPa, an inlet air temperature of 150°C, and an outlet air temperature of 75°C. S2, in lithium-rich manganese-based cathode material Li 1.15 Ni 0.10 Co 0.10 Mn 0.60 The surface-coated mixture of O2, based on the mass of lithium-rich manganese-based cathode material, contains 4 wt% polyacrylamide-3 and 0.003 wt% manganese carbonate. The weight-average molecular weight of polyacrylamide-3 is 4.5 million, and the average particle size is 50 nm. The average particle size of manganese carbonate is 50 nm. The mixture is heated to 600 °C at a heating rate of 2 °C and sintered for 6 h to obtain the coated lithium-rich manganese-based cathode material.

[0042] Example 4 This embodiment provides a method for preparing a lithium-rich manganese-based cathode material, including the following steps: S1, acrylamide / acrylic acid copolymer, 1 mol / L manganese sulfate solution and 1 mol / L sodium carbonate solution are mixed and spray-dried at a pressure of 0.5 MPa, an inlet air temperature of 180℃ and an outlet air temperature of 65℃. S2, in lithium-rich manganese-based cathode material Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 The O2 surface-coated mixture, based on the mass of the lithium-rich manganese-based cathode material, contains 5 wt% acrylamide / acrylic acid copolymer and 0.002 wt% manganese carbonate. The weight-average molecular weight of the acrylamide / acrylic acid copolymer is 8.5 million, the average particle size is 30 nm, and the average particle size of the manganese carbonate is 50 nm. The mixture is heated to 550 °C at a heating rate of 3 °C and sintered for 6 h to obtain the lithium-rich manganese-based cathode material.

[0043] Example 5 This embodiment provides a method for preparing a lithium-rich manganese-based cathode material, including the following steps: S1, mix polyacrylamide-4, a 1 mol / L manganese sulfate solution and a 1 mol / L sodium carbonate solution, and spray dry them at a pressure of 0.5 MPa, an inlet air temperature of 180℃ and an outlet air temperature of 65℃. S2, in lithium-rich manganese-based cathode material Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 The O2 surface-coated mixture, based on the mass of the lithium-rich manganese-based cathode material, contains 5 wt% polyacrylamide-4 and 0.002 wt% manganese carbonate. The weight-average molecular weight of polyacrylamide-4 is 60,000, the average particle size is 30 nm, and the average particle size of manganese carbonate is 50 nm. The mixture is heated to 550 °C at a heating rate of 3 °C and sintered for 6 h to obtain the lithium-rich manganese-based cathode material.

[0044] Example 6 This embodiment provides a method for preparing a lithium-rich manganese-based cathode material, including the following steps: S1, mix polyacrylamide-1, a 1 mol / L manganese sulfate solution and a 1 mol / L sodium carbonate solution, and spray dry them at a pressure of 0.5 MPa, an inlet air temperature of 180℃ and an outlet air temperature of 65℃. S2, in lithium-rich manganese-based cathode material Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 The O2 surface-coated mixture, based on the mass of the lithium-rich manganese-based cathode material, contains 4.5 wt% polyacrylamide-1 and 0.0015 wt% manganese carbonate. The weight-average molecular weight of polyacrylamide-1 is 8.5 million, the average particle size is 30 nm, and the average particle size of manganese carbonate is 50 nm. The mixture is heated to 550 °C at a heating rate of 3 °C and sintered for 6 h to obtain the lithium-rich manganese-based cathode material.

[0045] Example 7 This embodiment provides a method for preparing a lithium-rich manganese-based cathode material, including the following steps: S1, according to Example 1, except that the spray drying pressure is 0.45 MPa, the inlet air temperature is 180°C, and the outlet air temperature is 65°C; S2, in accordance with the method of Example 1.

[0046] Example 8 This embodiment provides a method for preparing a lithium-rich manganese-based cathode material, including the following steps: S1, according to the method of Example 1; S2, following the method of Example 1, except that the temperature is increased to 600°C at a heating rate of 3°C and sintered for 8 hours.

[0047] Comparative Example 1 This comparative example provides a method for preparing a lithium-rich manganese-based cathode material, comprising the following steps: S1, according to the method of Example 8; S2, following the method of Example 8, except that instead of coating the surface of the lithium-rich manganese-based cathode material with a mixture, manganese carbonate is coated on the surface of the lithium-rich manganese-based cathode material. That is, the percentage of manganese carbonate used is 5.002 wt% based on the mass of the lithium-rich manganese-based cathode material (the sum of the amounts of polyacrylamide-1 and manganese carbonate used in Example 8). The material is heated to 600°C at a heating rate of 3°C and sintered for 6 hours to obtain the coated lithium-rich manganese-based cathode material.

[0048] Comparative Example 2 This comparative example provides a method for preparing a lithium-rich manganese-based cathode material, comprising the following steps: S1, following the method of Example 8, except that spray drying is replaced with forced air drying, and drying is carried out at 150°C for 10 hours; S2, according to the method of Example 8.

[0049] Test case Battery preparation method: The materials obtained in the examples and comparative examples, Super P, and PVDF were mixed at a mass ratio of 92:4:4 to obtain a positive electrode mixture. The positive electrode mixture was then mixed with N-methylpyrrolidone (NMP) to form a slurry, wherein the ratio of the positive electrode mixture to NMP was 2:1 (g / mL). The slurry was coated on aluminum foil with an areal density of 10 mg / cm³. 2 After drying, a positive electrode sheet is prepared. A negative electrode mixture is obtained by mixing graphite, binder (LA133), and carbon nanotubes (CNTs) in a mass ratio of 90:5:5. The negative electrode mixture and NMP are then coated onto copper foil in a ratio of 2:1 (g / mL), resulting in an areal density of 10 mg / cm³. 2 After drying, a negative electrode sheet is prepared; the electrolyte is a 1 mol / L LiPF6 ethylene carbonate (EC) and dimethyl carbonate (DMC) solution, wherein the volume ratio of EC to DMC is 1:1; the positive electrode sheet, separator (PE / PP composite membrane), negative electrode sheet and electrolyte are assembled into a 2025 type coin cell in an Ar gas glove box with a water content and oxygen content of less than 5 ppm.

[0050] At 25℃, the voltage was first charged at a constant current rate of 0.1C to 4.8V, and then first discharged at a rate of 0.1C to 3.0V to obtain the 0.1C charge / discharge capacity. The 0.1C charge / discharge specific capacity was then calculated. First charge efficiency: First discharge capacity / First charge capacity × 100%; Test method for rate performance: Under 25℃ conditions, the battery is charged to 4.8V at a constant current of 0.1C, discharged to 3.0V at a constant current of 0.1C, then charged to 4.8V at a constant current of 1C, and discharged to 3.0V at a constant current of 1C; Retention rate at 5C = 5C discharge capacity / first 0.1C discharge capacity × 100%; The capacity retention rate test method is as follows: At 25℃, the battery is charged at a constant current of 5C to 4.8V, discharged at a constant current of 5C to 3.0V, and cycled for 50 times. The capacity retention rate on the 50th cycle = (5C discharge capacity on the 50th cycle / 5C discharge capacity on the 1st cycle) × 100%. The test results are shown in Table 1. Table 1

[0051] A comparison of Examples 1 and 4 shows that when the acrylamide polymer in Example 1 is polyacrylamide, the surface is neutral and no additional charge is introduced. Compared with copolymers, it has better flexibility, more uniform coating, and better electrical properties.

[0052] A comparison of Examples 1 and 5 shows that the specific weight-average molecular weight of polyacrylamide in Example 1 can further control its film-forming ability, thereby affecting its electrical properties.

[0053] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a lithium-rich manganese-based cathode material, characterized in that, The preparation method includes the following steps: S1, an acrylamide polymer and a metal coating agent are mixed and then spray-dried to obtain a mixture; S2, the mixture is coated onto the surface of the lithium-rich manganese-based cathode material and sintered to obtain the coated lithium-rich manganese-based cathode material.

2. The production method according to claim 1, characterized by, The acrylamide polymers include at least one of polyacrylamide, acrylamide / acrylic acid copolymer, and acrylamide / acrylate copolymer; And / or, the weight-average molecular weight of the acrylamide polymer is 10,000 to 20,000,000.

3. The preparation method according to claim 2, characterized in that, The acrylamide polymer is polyacrylamide; And / or, the weight-average molecular weight of the acrylamide polymer is 200,000 to 10,000,000.

4. The production method according to any one of claims 1 to 3, characterized by, Based on lithium-rich manganese-based cathode material, the percentage of acrylamide polymer is 3-6 wt%, and the percentage of metal coating agent is 0.001-0.01 wt%. Optionally, based on lithium-rich manganese-based cathode material, the percentage of acrylamide polymer is 4.8-5 wt%, and the percentage of metal coating agent is 0.002-0.01 wt%. And / or, the average particle size of the acrylamide polymer is 0.1 nm-10 μm, optionally 0.1-100 nm; And / or, the average particle size of the metal coating agent is 0.1 nm-5 μm, optionally 5-50 nm, and further optionally 10-30 nm; And / or, the metal coating agent includes at least one of a metal oxide and its precursor, a metal carbonate and its precursor.

5. The preparation method according to claim 4, characterized in that, The metal oxide includes at least one of manganese oxide, silicon oxide, and titanium oxide; And / or, the metal carbonate includes at least one of manganese carbonate, strontium carbonate, tungsten carbonate, and yttrium carbonate.

6. The method of any one of claims 1-5, wherein, The conditions for spray drying include: pressure of 0.1-0.8 MPa, inlet air temperature of 100-300℃, and outlet air temperature of 50-100℃. Optionally, the spray drying conditions include: a pressure of 0.2-0.7 MPa, an inlet air temperature of 120-250°C, and an outlet air temperature of 60-80°C.

7. The method of any one of claims 1-6, wherein, The sintering conditions include: heating to 500-600℃ at a heating rate of 1-5℃ and sintering for 5-8 hours; Optionally, the sintering conditions include sintering at 550-580°C.

8. The method of any one of claims 1-7, wherein, The general formula of the lithium-rich manganese-based cathode material is Li. x Ni a Co b Mn c O2, where 1≤x≤1.2, 0.10≤a≤0.30, 0≤b≤0.15, and 0.50≤c≤0.

60.

9. A lithium-rich manganese-based cathode material prepared by the preparation method according to any one of claims 1-8.

10. A secondary battery characterized by comprising: The secondary battery includes the lithium-rich manganese-based cathode material as described in claim 9.

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