Boron-zinc double-doped manganese-rich-based positive electrode material coated with nitrogen-containing carbon material and preparation method and application of boron-zinc double-doped manganese-rich-based positive electrode material

Abstract

The invention provides a boron-zinc double-doped manganese-rich-based positive electrode material coated with a nitrogen-containing carbon material and a preparation method and application thereof, and belongs to the technical field of electrode materials. The preparation method comprises the following steps: mixing a manganese-based ternary hydroxide precursor, a lithium salt and zinc borate, and then carrying out ball milling treatment and calcination treatment to obtain the boron-zinc double-doped manganese-rich-based positive electrode material. And mixing the boron-zinc double-doped manganese-rich-base positive electrode material and a nitrogen-containing organic matter in a solvent, and then carrying out spray drying and carbonization treatment to obtain the nitrogen-containing carbon material coated boron-zinc double-doped manganese-rich-base positive electrode material. Boron ions and zinc ions are embedded into the boron-zinc double-doped manganese-rich-based positive electrode material coated with the nitrogen-containing carbon material, the outside of the boron-zinc double-doped manganese-rich-based positive electrode material coated with the nitrogen-containing carbon material is coated with the nitrogen-containing carbon layer, boron-oxygen chemical bonds in the positive electrode material are stabilized through doping of the boron ions, meanwhile, oxygen loss is prevented, and the interplanar spacing of the material is increased through doping of the zinc ions; and meanwhile, the layered electrode is supported and protected in the charging and discharging process, so that the process of converting the layered material into spinel is inhibited.

Description

Technical Field

[0001] This invention relates to the field of electrode materials technology, and in particular to a boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-containing carbon material, its preparation method, and its application. Background Technology

[0002] With the rapid development of the new energy vehicle industry and the ever-changing nature of electronic products, the demand for high-energy-density lithium-ion batteries is becoming increasingly strong. It is well known that cathode materials have a crucial impact on the energy density of lithium-ion batteries. However, existing ternary materials and lithium iron phosphate materials have energy densities below 250Wh / kg, which can no longer meet the growing demand for high-energy lithium-ion batteries. Lithium-rich manganese cathode materials, due to their high specific capacity and voltage plateau, can achieve energy densities exceeding 350Wh / kg, while also possessing the advantage of low cost, and are considered the most promising next-generation lithium-ion cathode material. However, problems such as low initial coulombic efficiency and poor cycle and coulombic efficiency in lithium-rich manganese materials severely limit their application. For example, when the initial charging voltage exceeds 4.5V, the inactive Li2MnO3 in lithium-rich manganese is activated and participates in the reaction, leading to O2O2 degradation. 2- The dissolution of oxygen makes the first charge and discharge of the battery severely irreversible, resulting in low coulombic efficiency. At the same time, after the lattice loses oxygen, it undergoes a process from layered to spinel to disordered structure, leading to a decrease in material voltage and capacity decay.

[0003] Existing technologies have proposed several improvement methods to address the defects in lithium-rich manganese. Some researchers have proposed carbon coating to improve the rate performance of the material. For example, in CN115966667A, nitrogen- and sulfur-doped carbon materials are coated onto the surface of lithium-rich manganese materials. The carbon materials, containing numerous active sites and defects, can enhance electron and ion transport rates and effectively suppress cathode material aggregation during cycling, thereby improving the initial coulombic efficiency and rate performance, and reducing voltage decay. Furthermore, the carbon coating can protect the surface structure of the lithium-rich manganese material, reducing contact with the electrolyte and thus minimizing side reactions, which improves the cycling performance to some extent. Besides coating, other researchers have used doping to improve the performance of lithium-rich manganese-based cathodes. Patent CN110429268A describes obtaining boron-doped lithium-rich manganese-based cathode materials by dissolving a boron source and sintering it at high temperature with a nickel-cobalt-manganese compound precursor. Boron doping can enhance chemical bond strength, thereby suppressing the phase transition from spinel to layered structure in lithium-rich manganese materials, thus improving material stability and ultimately enhancing capacity and cycle performance. Addressing the structural instability and poor conductivity of existing lithium-rich manganese cathode materials during charge and discharge, researching a boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-carbon material, its preparation method, and its applications is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-containing carbon material, its preparation method and application, so as to solve the problems of low initial coulombic efficiency, poor cycle and coulombic efficiency of lithium-rich manganese cathode materials in the prior art.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing a boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-containing carbon material, comprising the following steps:

[0007] (1) Manganese-based ternary hydroxide precursor, lithium salt and zinc borate are mixed and then ball-milled and calcined to obtain boron-zinc double-doped manganese-rich cathode material.

[0008] (2) The boron-zinc double-doped manganese-rich cathode material and nitrogen-containing organic matter are mixed in a solvent, and then spray-dried and carbonized to obtain a boron-zinc double-doped manganese-rich cathode material coated with nitrogen-containing carbon material.

[0009] The chemical formula of the manganese-based ternary hydroxide precursor is Mn. x Ni (1-x-y) Co y (OH)2, where 0.4≤x≤0.6, 0≤y≤0.2.

[0010] Preferably, in step (1), the molar ratio of lithium in the manganese-based ternary hydroxide precursor and the lithium salt is 1.9 to 2.1:1; and the mass ratio of the manganese-based ternary hydroxide precursor and zinc borate is 1:0.05 to 0.2.

[0011] Preferably, in step (1), the ball milling speed is 100-1000 rpm and the ball milling time is 2-8 h.

[0012] Preferably, in step (1), the heating rate during calcination is 0.5 to 20 °C / min, the calcination temperature is 600 to 1000 °C, and the calcination time is 50 to 600 min.

[0013] Preferably, in step (2), the mass ratio of the boron-zinc dual-doped manganese-rich cathode material to the nitrogen-containing organic material is 5-7:2-1; the nitrogen-containing organic material is polyaniline.

[0014] Preferably, in step (2), the solvent is an alcohol solution; the mass-to-volume ratio of the boron-zinc dual-doped manganese-rich cathode material to the solvent is 1-1.8 g: 1 mL.

[0015] Preferably, in step (2), the heating rate during carbonization is 0.5 to 20 °C / min, the carbonization temperature is 600 to 1000 °C, and the carbonization time is 50 to 600 min.

[0016] This invention provides a boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-containing carbon material, which is prepared by the above-described method for preparing a boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-containing carbon material.

[0017] The present invention also provides a positive electrode sheet comprising a boron-zinc dual-doped manganese-rich positive electrode material coated with the nitrogen-containing carbon material described above.

[0018] The present invention also provides a lithium-ion battery comprising the above-described positive electrode sheet.

[0019] The beneficial effects of this invention are:

[0020] The boron-zinc dual-doped manganese-rich cathode material of the present invention, coated with nitrogen-carbon material, has boron and zinc particles embedded inside and is coated with a nitrogen-carbon layer on the outside. The doping of boron ions can stabilize the boron oxide chemical bonds inside the cathode material while preventing oxygen loss. The doping of zinc ions can increase the inter-crystal spacing of the material and effectively support and protect the layered electrode during charging and discharging, thus suppressing the transformation of the layered material into spinel.

[0021] Nitrogen-carbon coating can effectively block electrolyte, protect manganese-rich cathode materials from corrosion, and improve the electronic conductivity of the materials. Nitrogen doping can introduce defect sites into graphite, promoting the diffusion of lithium ions.

[0022] In the preparation of boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-carbon material, spray drying is used for secondary granulation to reduce the specific surface area of ​​lithium-rich manganese cathode material, thereby reducing its direct contact with electrolyte and improving the cycle performance of cathode material. Attached Figure Description

[0023] Figure 1 A schematic diagram of the cross-sectional structure of a boron-zinc dual-doped manganese-rich cathode material;

[0024] Figure 2 This is a schematic diagram of the cross-sectional structure of a boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-containing carbon materials. Figure 1 , Figure 2 In the diagram, 100 represents zinc ions, 101 represents boron ions, 102 represents lithium-rich manganese-based materials, 103 represents carbon material coating layers, and 104 represents nitrogen atoms. Detailed Implementation

[0025] This invention provides a method for preparing a boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-containing carbon material, comprising the following steps:

[0026] (1) Manganese-based ternary hydroxide precursor, lithium salt and zinc borate are mixed and then ball-milled and calcined to obtain boron-zinc double-doped manganese-rich cathode material.

[0027] (2) The boron-zinc double-doped manganese-rich cathode material and nitrogen-containing organic matter are mixed in a solvent, and then spray-dried and carbonized to obtain a boron-zinc double-doped manganese-rich cathode material coated with nitrogen-containing carbon material.

[0028] The chemical formula of the manganese-based ternary hydroxide precursor is Mn. x Ni (1-x-y) Co y (OH)2, where 0.4≤x≤0.6, 0≤y≤0.2.

[0029] In this invention, in step (1), the molar ratio of the manganese-based ternary hydroxide precursor to lithium in the lithium salt is 1.9 to 2.1:1, preferably 2:1; the mass ratio of the manganese-based ternary hydroxide precursor to zinc borate is 1:0.05 to 0.2, preferably 1:0.08 to 0.015, and more preferably 1:0.1.

[0030] In this invention, in step (1), the ball milling speed is 100-1000 rpm, preferably 200-800 rpm, more preferably 300-600 rpm, and the ball milling time is 2-8 h, preferably 3-7 h, more preferably 5-6 h.

[0031] In this invention, in step (1), the heating rate during the calcination treatment is 0.5-20℃ / min, preferably 5-15℃ / min, more preferably 10℃ / min, the calcination temperature is 600-1000℃, preferably 700-900℃, more preferably 800℃, and the calcination time is 50-600min, preferably 120-500min, more preferably 180-420min.

[0032] In this invention, in step (2), the mass ratio of the boron-zinc dual-doped manganese-rich cathode material to the nitrogen-containing organic matter is 5-7:2-1, specifically 3:1, 5:1, 6:1, or 7:1; the nitrogen-containing organic matter is polyaniline.

[0033] In this invention, in step (2), the solvent is an alcohol solution; the mass-volume ratio of the boron-zinc dual-doped manganese-rich cathode material to the solvent is 1-1.8 g: 1 mL, preferably 1.2-1.6 g: 1 mL, and more preferably 1.3-1.5 g: 1 mL.

[0034] In this invention, the alcohol solution comprises an ethanol solution, a n-propanol solution, or an isopropanol solution.

[0035] In this invention, the process parameters for spray drying are: inlet air temperature 180-220℃, outlet air temperature 80-110℃, feed rate 5-20mL / min, atomization pressure 0.2-0.4MPa, and centrifugal speed 15000-25000rpm.

[0036] In this invention, in step (2), the heating rate during carbonization is 0.5 to 20°C / min, preferably 5 to 15°C / min, more preferably 10°C / min, the carbonization temperature is 600 to 1000°C, preferably 700 to 900°C, more preferably 800°C, and the carbonization time is 50 to 600 min, preferably 120 to 500 min, more preferably 180 to 420 min.

[0037] In this invention, the carbonization process is carried out in an inert atmosphere.

[0038] This invention provides a boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-containing carbon material, which is prepared by the above-described method for preparing a boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-containing carbon material.

[0039] The present invention also provides a positive electrode sheet comprising a boron-zinc dual-doped manganese-rich positive electrode material coated with the nitrogen-containing carbon material described above.

[0040] In this invention, the positive electrode sheet is prepared by mixing a boron-zinc double-doped manganese-rich positive electrode material coated with nitrogen-carbon material with a conductive agent and a binder, adding a solvent and stirring evenly to form a positive electrode slurry, then coating the positive electrode slurry onto an aluminum foil, and drying it to obtain a positive electrode sheet.

[0041] The present invention also provides a lithium-ion battery comprising the above-described positive electrode sheet.

[0042] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0043] Example 1

[0044] According to Mn 0.6 Ni 0.2 Co 0.2 The molar ratio of lithium in (OH)2 and lithium carbonate is 2:1. Mn 0.6 Ni 0.2 Co 0.2 (OH)2 and lithium carbonate are mixed, and zinc borate (of which Mn) is added. 0.6 Ni 0.2 Co 0.2 The (OH)2 and zinc borate were ball-milled at 600 rpm for 5 h, and then calcined at 800 °C at a heating rate of 10 °C / min under oxygen-enriched conditions for 120 min to obtain boron-zinc dual-doped manganese-rich cathode material.

[0045] Boron-zinc dual-doped manganese-rich cathode material and polyaniline were mixed in an ethanol solution with a mass ratio of 5:1, an ethanol solution concentration of 60%, and a mass-to-volume ratio of 1.5 g:1 mL. After thorough mixing, the mixture was spray-dried using the following parameters: inlet air temperature 200℃, outlet air temperature 100℃, feed rate 15 mL / min, atomization pressure 0.3 MPa, and rotation speed 20000 rpm. The spray-dried particles were then placed in an argon atmosphere and heated to 800℃ at a rate of 10℃ / min for carbonization, and held at this temperature for 120 min to obtain a boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-carbon material.

[0046] Example 2

[0047] According to Mn 0.6 Ni 0.2 Co0.2 The molar ratio of lithium in (OH)₂ and lithium carbonate is 2.1:1. Mn 0.6 Ni 0.2 Co 0.2 (OH)2 and lithium carbonate are mixed, and zinc borate (of which Mn) is added. 0.6 Ni 0.2 Co 0.2 The (OH)2 and zinc borate were ball-milled at 300 rpm for 8 hours, and then calcined at 1000℃ under oxygen-enriched conditions at a heating rate of 20℃ / min and held for 180 min to obtain a boron-zinc dual-doped manganese-rich cathode material.

[0048] Boron-zinc dual-doped manganese-rich cathode material and polyaniline were mixed in an ethanol solution with a mass ratio of 7:1 and an ethanol solution concentration of 60% and a mass-to-volume ratio of 1g:1mL. After uniform mixing, the mixture was spray-dried using the following process parameters: inlet air temperature 200℃, outlet air temperature 100℃, feed rate 15mL / min, atomization pressure 0.3MPa, and rotation speed 20000rpm. The spray-dried particles were then placed in an argon atmosphere and heated to 1000℃ at a heating rate of 20℃ / min for carbonization, and held at that temperature for 100min to obtain a boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-carbon material.

[0049] Example 3

[0050] According to Mn 0.6 Ni 0.2 Co 0.2 The molar ratio of lithium in (OH)₂ and lithium carbonate is 1.9:1. Mn 0.6 Ni 0.2 Co 0.2 (OH)2 and lithium carbonate are mixed, and zinc borate (of which Mn) is added. 0.6 Ni 0.2 Co 0.2 The (OH)2 and zinc borate were ball-milled at 1000 rpm for 2 hours, and then calcined at 600℃ under oxygen-enriched conditions at a heating rate of 5℃ / min, and held at that temperature for 600 min to obtain a boron-zinc dual-doped manganese-rich cathode material.

[0051] Boron-zinc dual-doped manganese-rich cathode material and polyaniline were mixed in an ethanol solution with a mass ratio of 6:1, an ethanol solution concentration of 60%, and a mass-to-volume ratio of 1.8 g:1 mL. After thorough mixing, the mixture was spray-dried using the following parameters: inlet air temperature 200℃, outlet air temperature 100℃, feed rate 15 mL / min, atomization pressure 0.3 MPa, and rotation speed 20000 rpm. The spray-dried particles were then placed in an argon atmosphere and heated to 600℃ at a rate of 5℃ / min for carbonization, and held at that temperature for 600 min to obtain a boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-carbon material.

[0052] Comparative Example 1

[0053] The difference from Example 1 is that boric acid was used instead of zinc borate, while all other conditions were the same, resulting in a boron-doped manganese-rich cathode material coated with nitrogen-containing carbon material.

[0054] Comparative Example 2

[0055] The difference from Example 1 is that zinc oxide was used instead of zinc borate, while all other conditions were the same, resulting in a zinc-doped manganese-rich cathode material coated with nitrogen-containing carbon material.

[0056] Comparative Example 3

[0057] According to Mn 0.6 Ni 0.2 Co 0.2 The molar ratio of lithium in (OH)2 and lithium carbonate is 2:1. Mn 0.6 Ni 0.2 Co 0.2 (OH)2 and lithium carbonate were mixed and ball-milled at 600 rpm for 5 hours. Then, under oxygen-enriched conditions, the mixture was heated to 800℃ at a heating rate of 10℃ / min and calcined for 120 minutes to obtain manganese-rich cathode material.

[0058] Manganese-rich cathode material and polyaniline were mixed in an ethanol solution with a mass ratio of 5:1, an ethanol solution concentration of 60%, and a mass-to-volume ratio of 1.5 g:1 mL. After thorough mixing, the mixture was spray-dried. The spray-drying process parameters were: inlet air temperature 200℃, outlet air temperature 100℃, feed rate 15 mL / min, atomization pressure 0.3 MPa, and rotation speed 20000 rpm. The spray-dried particles were placed in an argon atmosphere and heated to 800℃ at a heating rate of 10℃ / min for carbonization, and held at that temperature for 120 min to obtain a manganese-rich cathode material coated with nitrogen-containing carbon material.

[0059] Comparative Example 4

[0060] According to Mn 0.6 Ni 0.2 Co 0.2 The molar ratio of lithium in (OH)2 and lithium carbonate is 2:1. Mn 0.6 Ni 0.2 Co 0.2 (OH)2 and lithium carbonate were mixed and ball-milled at 500 rpm for 5 hours. Then, under oxygen-enriched conditions, the mixture was heated to 800℃ at a heating rate of 10℃ / min and calcined for 120 minutes to obtain manganese-rich cathode material.

[0061] Manganese-rich cathode material was dissolved in an ethanol solution with a concentration of 60%. The mass-to-volume ratio of boron-zinc co-doped manganese-rich cathode material to ethanol solution was 1.5 g: 1 mL. After uniform mixing, the mixture was spray-dried. The spray-drying process parameters were: inlet air temperature 200℃, outlet air temperature 100℃, feed rate 15 mL / min, atomization pressure 0.3 MPa, and rotation speed 20000 rpm. The spray-dried particles were placed in an argon atmosphere and heated to 800℃ at a heating rate of 10℃ / min for carbonization. The temperature was held for 120 min to obtain carbon-coated manganese-rich cathode material.

[0062] Electrochemical performance testing:

[0063] The boron-zinc dual-doped manganese-rich cathode materials coated with nitrogen-containing carbon materials in Examples 1-3 and the cathode materials in Comparative Examples 1-4 were respectively prepared into cathode sheets. The preparation method of the cathode sheet was as follows: the cathode active material (lithium iron phosphate), conductive agent (carbon black), and binder (polyvinylidene fluoride) were dissolved in N-methylpyrrolidone (NMP) solution at a mass ratio of 90:5:5, and stirred thoroughly to achieve uniform dispersion, thus obtaining a cathode slurry. The cathode slurry was coated onto a cathode aluminum foil coated with a safety primer to a thickness of 80 μm, dried at 120°C for 2 h, and then hot-pressed at a pressure of 5 MPa to obtain the cathode sheet.

[0064] The aforementioned positive electrode sheet was fabricated, wound, and packaged to obtain a lithium-ion battery. The initial charge-discharge specific capacity and initial efficiency were then tested under conditions of 3.0V–4.48V and a current density of 0.2C. The discharge specific capacity and capacity retention after 500 cycles were tested under a current density of 0.5C. Furthermore, rate performance testing was performed on the battery under constant current charge-discharge conditions of 0.2C, 0.5C, 1C, 1.5C, 2C, 3C, and 0.2C. The test results are shown in Table 1.

[0065] Table 1. Test results of lithium ions in Examples 1-3 and Comparative Examples 1-4

[0066]

[0067] Table 1 shows that, compared with Comparative Example 4, Comparative Example 3 exhibits superior first-efficiency performance, rate discharge performance, cycle capacity retention, and cycle voltage decay. This indicates that nitrogen-doped carbon materials can effectively improve the first-efficiency performance, rate discharge performance, cycle capacity retention, and cycle voltage decay of lithium-rich manganese-based cathode materials.

[0068] Comparative Examples 1 and 2 showed higher initial efficiency, rate discharge performance, cycle capacity retention, and cycle voltage decay performance than Comparative Example 3, indicating that single doping with boron or zinc can improve the initial efficiency, rate discharge performance, cycle capacity retention, and cycle voltage decay of lithium-ion batteries to a certain extent.

[0069] Comparing Comparative Example 1 and Comparative Example 2, it can be seen that boron doping is beneficial to the rate discharge performance and cycle performance of lithium-ion batteries; while zinc doping can effectively improve the initial efficiency and cycle voltage decay of lithium-ion batteries.

[0070] Comparing Example 1 with Comparative Examples 1-4, it can be seen that the boron-zinc dual-doped lithium-rich manganese-based cathode material coated with nitrogen-carbon material can significantly enhance the initial efficiency, rate discharge performance, cycle performance, and voltage decay of lithium-ion batteries. The technical principle is as follows: By supporting the structure of the lithium-rich manganese-based material through boron and zinc dual doping, the transformation of the lithium-rich manganese-based substrate structure to a spinel structure is suppressed. Simultaneously, the formation of boron-oxygen bonds (BO) between boron and oxygen elements suppresses oxygen evolution, thereby improving the cycle life of the material. Furthermore, the nitrogen-carbon coating layer can reduce side reactions between the lithium-rich manganese-based material and the electrolyte, while also enhancing the material's conductivity, thus improving the battery's coulombic efficiency and cycle life.

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a nitrogen-containing carbon material-coated boron-zinc co-doped manganese-rich cathode material, characterized in that, The method comprises the following steps: (1) mixing a manganese-based ternary hydroxide precursor, a lithium salt and zinc borate, and then performing ball milling treatment and calcination treatment to obtain a boron-zinc double-doped manganese-rich positive electrode material; (2) mixing the boron-zinc double-doped manganese-rich positive electrode material and a nitrogen-containing organic substance in a solvent, and then performing spray drying and carbonization treatment to obtain a boron-zinc double-doped manganese-rich positive electrode material coated with a nitrogen-containing carbon material. The manganese-based ternary hydroxide precursor has a chemical formula of Mn x Ni (1-x-y) Co y (OH)2, wherein 0.4≤x≤0.6, 0≤y≤0.

2.

2. The method for preparing the boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-containing carbon material according to claim 1, characterized in that, In step (1), the molar ratio of the manganese-based ternary hydroxide precursor to lithium in the lithium salt is 1.9-2.1:1; and the mass ratio of the manganese-based ternary hydroxide precursor to zinc borate is 1:0.05-0.

2.

3. The method of producing a nitrogen-carbide-coated boron-zinc co-doped manganese-rich cathode material according to claim 1 or 2, characterized in that, In step (1), the rotation speed of the ball milling treatment is 100-1000 rpm, and the ball milling treatment time is 2-8 h.

4. The method for preparing the boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-containing carbon material according to claim 3, characterized in that, In step (1), the temperature rising rate of the calcination treatment is 0.5-20 ℃ / min, the calcination treatment temperature is 600-1000 ℃, and the calcination treatment time is 50-600 min.

5. The method of producing a nitrogen-carbide-coated boron-zinc co-doped manganese-rich cathode material according to claim 1 or 2 or 4, characterized in that, In step (2), the mass ratio of the boron-zinc double-doped manganese-rich positive electrode material to the nitrogen-containing organic substance is 5-7:2-1; and the nitrogen-containing organic substance is polyaniline.

6. The method for preparing the boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-containing carbon material according to claim 5, characterized in that, In step (2), the solvent is an alcohol solution; and the mass-volume ratio of the boron-zinc double-doped manganese-rich positive electrode material to the solvent is 1-1.8 g:1 mL.

7. The method for preparing a boron-zinc dual-doped manganese-rich cathode material coated with nitrogen-containing carbon material according to claim 4 or 6, characterized in that, In step (2), the temperature rising rate of the carbonization treatment is 0.5-20 ℃ / min, the carbonization treatment temperature is 600-1000 ℃, and the carbonization treatment time is 50-600 min.

8. A nitrogen-carbon material-coated boron-zinc co-doped manganese-rich cathode material, characterized in that, The boron-zinc double-doped manganese-rich positive electrode material coated with a nitrogen-containing carbon material is prepared by the method of any one of claims 1-7.

9. A positive electrode sheet characterized by comprising: The boron-zinc double-doped manganese-rich positive electrode material coated with a nitrogen-containing carbon material of claim 8.

10. A lithium-ion battery, characterized by, The positive electrode sheet of claim 9.

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