Preparation method of lithium-rich manganese-based positive electrode material without voltage attenuation

Abstract

This invention provides a method for preparing a lithium-rich manganese-based cathode material with no voltage decay, belonging to the field of new energy technology. The method includes: dispersing Ni salt, excess Mn salt, and a salt or oxide of element A in water, and obtaining a precursor through co-precipitation; mixing the precursor, Ni source, and Li source uniformly to obtain a mixture; and sintering the mixture to obtain the lithium-rich manganese-based cathode material with no voltage decay. During the co-precipitation process, the molar ratio of Ni in the Ni salt to Mn in the Mn salt is 0.01 ≤ x ≤ 0.33; when mixing the precursor with the Ni source and Li source, an appropriate amount of Ni source is added to adjust the molar ratio of Ni to Mn in the mixture to 1:3. This invention, by adjusting the Ni and Mn ratio in the co-precipitation precursor, directionally controls the Li₂MnO₃ phase, thereby improving the redox reversibility of lattice oxygen and preparing a high-capacity, oxygen-free, and voltage-decay-free lithium-rich manganese-based cathode material. The method of this invention is a solid-state sintering process, simple and suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to a method for preparing a lithium-rich manganese-based cathode material for lithium-ion batteries without voltage decay, belonging to the field of new energy technology. Background Technology

[0002] Technological and societal advancements have placed higher demands on the energy density of lithium-ion batteries, with the main bottleneck currently being the lack of high-specific-energy cathode materials. Among cathode materials, lithium-rich manganese-based cathode materials possess extremely high specific energy, reaching 350 Wh / kg, and do not require expensive cobalt, thus attracting considerable attention. Lithium-rich manganese-based cathode materials contain Li₂MnO₃ and LiNi. 0.5 Mn 0.5 In the Li₂MnO₃ two-phase system, the lattice oxygen in the Li₂MnO₃ phase undergoes redox reactions during charge and discharge, providing additional capacity. However, this easily leads to oxygen release, causing structural damage, severe voltage decay, inability to maintain high specific energy, and safety issues. To improve the long-cycle stability of lithium-rich manganese-based cathode materials, research institutions and companies have made numerous efforts. The most common methods are elemental doping and surface coating. However, because traditional modification methods often cannot precisely target the Li₂MnO₃ phase to regulate the redox reactions of lattice oxygen, the voltage decay problem remains difficult to solve. Therefore, developing new modification strategies is crucial and urgent. Summary of the Invention

[0003] This invention proposes a simple, effective, and novel improvement strategy aimed at suppressing structural damage and oxygen release in lithium-rich manganese-based oxide materials, thereby solving the voltage decay problem in lithium-rich manganese-based oxide materials.

[0004] This invention provides a method for preparing a lithium-rich manganese-based cathode material with no voltage decay. The method includes: obtaining a precursor with excess Mn through co-precipitation; mixing the precursor with a Ni source and a Li source uniformly; and then sintering the mixture to obtain the lithium-rich manganese-based cathode material. By adjusting the Ni and Mn ratio in the co-precipitated precursor, the Li₂MnO₃ phase is directionally controlled, thereby improving the redox reversibility of lattice oxygen. The resulting material has the general chemical formula Li₂MnO₃. 1.2 Ni 0.2 Mn 0.6-α A α The specific preparation method for O2 is as follows:

[0005] (1) Weigh out Ni salt, Mn salt and one or more salts or oxides of A, disperse them in water to obtain a metal ion solution; dissolve the precipitant in water or ethanol to obtain a precipitant solution. Add the precipitant solution to the metal ion solution and stir until the reaction is complete. Centrifuge the precipitate and wash it successively with deionized water and ethanol, and dry it to obtain the precursor;

[0006] (2) Mix the precursor, Ni source and Li source obtained in (1) evenly to obtain a mixture;

[0007] (3) The mixture obtained in (2) is placed in a muffle furnace for sintering to obtain the lithium-rich manganese-based cathode material.

[0008] In the chemical formula Li 1.2 Ni 0.2 Mn 0.6-α A α In O2, A is one or more of the elements Co, Fe, Mg, Al, Cu, Cr, Zr, Ti, Sc, Zn, Sn, Si, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Yb. The content of A in the general chemical formula is 0.005 ≤ α ≤ 0.1.

[0009] In step (1), the Ni salt is one or more of NiSO4, Ni(NO3)2, and NiCl2, the Mn salt is one or more of MnSO4, Mn(NO3)2, and MnCl2, and the A salt or oxide is a salt or oxide containing the element A. The types of A are as described in claim 2, including but not limited to CoSO4, FeSO4, Zr(CH3COO)4, TiO2, and MgO. The molar ratio of Ni in the Ni salt: Mn in the Mn salt: A in the A salt or oxide is x:3:y, 0.3≤x≤1, 0.025≤y≤0.5.

[0010] In step (1), the total metal ion concentration in the metal ion solution is ≥1 mol / L, and the charge concentration of the precipitant solution is as close as possible to the total metal ion charge concentration in the metal ion solution. The precipitant is one of oxalic acid, sodium oxalate, or sodium carbonate.

[0011] In step (2), the Ni source is one or more of NiO, NiCO3, and Ni(NO3)2, and the Li source is one of LiOH, LiOH·H2O, LiNO3, and Li2CO3.

[0012] In step (2), appropriate amounts of Ni source and Li source are added so that the molar ratio of Ni, Mn and Li in the final mixture is 1:3:z, 6≤z≤7. The actual addition ratio of Ni source depends on the molar ratio of Ni salt and Mn salt in step (1).

[0013] In step (3), the sintering process consists of five stages: heating, holding at a constant temperature, heating again, holding at a constant temperature, and cooling down. The heating rate for the first heating stage is 1–3 °C / min, the temperature for the first holding at a constant temperature is 300–600 °C, and the holding time is 3–10 h. The heating rate for the second heating stage is 3–6 °C / min, the temperature for the second holding at a constant temperature is 700–1000 °C, and the holding time is 10–24 h. The cooling process is a natural cooling process.

[0014] The present invention also includes a lithium-rich manganese-based cathode material, which is obtained by the above preparation method.

[0015] The advantages of this invention are as follows:

[0016] This invention provides a method for preparing lithium-rich manganese-based oxide materials without voltage decay. This solves the problem of voltage decay during long-cycle operation of lithium-rich manganese-based oxide materials.

[0017] This invention achieves oxygen-free release of lithium-rich manganese-based cathode materials by adjusting the Ni and Mn ratio in the co-precipitation precursor to directionally regulate the Li2MnO3 phase.

[0018] The method of this invention has a simple synthesis process, high yield, good product uniformity, and is suitable for large-scale production. Furthermore, the reaction raw materials are readily available, non-toxic, and inexpensive. Attached Figure Description

[0019] Figure 1 (a) and (b) are XRD patterns of the lithium-rich manganese-based cathode material with no voltage decay prepared by the method of the present invention and the ordinary lithium-rich manganese-based oxide material, respectively.

[0020] Figure 2 (a) and (b) are respectively a comparison of the discharge specific capacity cycling performance and the rate performance of the lithium-rich manganese-based cathode material with no voltage decay prepared by the method of the present invention and the ordinary lithium-rich manganese-based oxide material under the conditions of 1C (250mA / g) and 4.8V cutoff voltage.

[0021] Figure 3 A comparison of the cell volume changes of the lithium-rich manganese-based cathode material with no voltage decay prepared by the method of the present invention and ordinary lithium-rich manganese-based cathode material during deep charge and discharge in the voltage window of 2.0-4.8V.

[0022] Figure 4 (a) and (b) are comparison graphs of O2 release during deep charge-discharge in the voltage window of 2.0-4.8V between the voltage decay-rich lithium manganese-based cathode material prepared by the method of the present invention and the ordinary lithium manganese-based cathode material. Detailed Implementation

[0023] The specific process of the present invention will be further described in detail below. Experimental steps not specifically described in the embodiments can be performed according to conventional experimental procedures in the art; the drugs and reagents mentioned in the embodiments can all be commercially available conventional drugs and reagents. Embodiments made by those skilled in the art based on the described embodiments, without any inventive breakthrough, are still within the protection scope of the present invention.

[0024] This invention provides a method for preparing a lithium-rich manganese-based cathode material with no voltage decay. The method includes: dispersing Ni salt, excess Mn salt, and a salt or oxide of element A in water, and obtaining a precursor through co-precipitation; mixing the precursor, Ni source, and Li source uniformly to obtain a mixture; and sintering the mixture to obtain the lithium-rich manganese-based cathode material. The resulting material has the general chemical formula Li. 1.2 Ni 0.2 Mn 0.6-α A α The specific preparation method for O2 is as follows:

[0025] (1) Ni salt, Mn salt, and one or more salts or oxides of A are dispersed in water to obtain a metal ion solution; a precipitant is dissolved in water or ethanol to obtain a precipitant solution. The precipitant solution is added to the metal ion solution and stirred until the reaction is complete. The precipitate is centrifuged and washed successively with deionized water and ethanol, and dried to obtain the precursor;

[0026] (2) Mix the precursor (1), Ni source and Li source evenly to obtain a mixture;

[0027] (3) The mixture obtained in (2) is placed in a muffle furnace for sintering to obtain the lithium-rich manganese-based cathode material.

[0028] In the chemical formula Li 1.2 Ni 0.2 Mn 0.6-α A α In O2, A is one or more of the elements Co, Fe, Mg, Al, Cu, Cr, Zr, Ti, Sc, Zn, Sn, Si, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Yb. The content of A in the general chemical formula is 0.005 ≤ α ≤ 0.1.

[0029] In step (1), the Ni salt is at least one of NiSO4, Ni(NO3)2, and NiCl2, the Mn salt is at least one of MnSO4, Mn(NO3)2, and MnCl2, and the salt or oxide of A is a salt or oxide containing element A. The types of element A are as described above, including but not limited to CoSO4, FeSO4, Zr(CH3COO)4, TiO2, and MgO.

[0030] In step (1), the total metal ion concentration in the metal ion solution is ≥1 mol / L, and the charge concentration of the precipitant solution is as close as possible to the total metal ion charge concentration in the metal ion solution. The precipitant is one of oxalic acid, sodium oxalate, or sodium carbonate.

[0031] In step (1), the molar ratio of Ni in Ni salt, Mn in Mn salt, and A in A salt or oxide is x:3:y, 0.3≤x≤1, 0.025≤y≤0.5.

[0032] In step (2), the Ni salt is one or more of NiO, NiCO3, and Ni(NO3)2, and the Li salt is one of LiOH, LiOH·H2O, LiNO3, and Li2CO3.

[0033] In step (2), an appropriate amount of Ni source and Li source are added so that the molar ratio of Ni, Mn and Li in the mixture is 1:3:z, 6≤z≤7. The actual proportion of Ni source depends on the molar ratio of Ni salt and Mn salt in step (1).

[0034] In step (3), the sintering process consists of five stages: heating, holding at a constant temperature, heating again, holding at a constant temperature, and cooling down. The heating rate for the first heating stage is 2–3 °C / min; the temperature for the first holding at a constant temperature is 300–600 °C, and the holding time is 3–10 h; the heating rate for the second heating stage is 3–6 °C / min; the temperature for the second holding at a constant temperature is 700–1000 °C, and the holding time is 10–24 h; the cooling process is natural cooling.

[0035] Example 1:

[0036] (1) Weigh out NiSO4, MnSO4, and MgSO4 according to the molar ratio of Ni:Mn:Mg of 0.8:3:0.5, disperse them in water to obtain a metal ion solution; dissolve oxalic acid in ethanol to obtain a precipitant solution. Add the precipitant solution to the metal ion solution and stir until the reaction is complete. Centrifuge the precipitate and wash it successively with deionized water and ethanol, and dry it to obtain the precursor;

[0037] (2) According to the molar ratio of Mn in the precursor: Ni in NiO: Li in LiOH·H2O is 3:0.2:6, weigh the precursor, NiO and LiOH·H2O, mix them evenly to obtain a mixture;

[0038] (3) The mixture obtained in (2) was placed in a muffle furnace and heated to 600°C at a rate of 3°C / min, and held for 5 h. Then the temperature was increased to 900°C at a rate of 5°C / min, and held for 16 h. After that, it was allowed to cool naturally to obtain the lithium-rich manganese-based cathode material.

[0039] Example 2:

[0040] (1) According to the molar ratio of Ni:Mn:Ti:Ce of 0.5:3:0.3:0.05, NiSO4, MnSO4, TiCl4, and Ce(NO3)3 were weighed and dispersed in water to obtain a metal ion solution; oxalic acid was dissolved in ethanol to obtain a precipitant solution. The precipitant solution was added to the metal ion solution and stirred until the reaction was complete. The precipitate was separated by centrifugation and washed successively with deionized water and ethanol, and dried to obtain the precursor;

[0041] (2) According to the molar ratio of Mn in the precursor: Ni in NiO: Li in LiOH·H2O is 3:0.5:6, weigh the precursor, NiO and LiOH·H2O, mix them evenly to obtain a mixture;

[0042] (3) The mixture obtained in (2) is placed in a muffle furnace and heated to 500°C at a rate of 3°C / min, and held at that temperature for 5 hours. Then, the temperature is increased to 800°C at a rate of 3°C / min and held at that temperature for 20 hours. After that, it is allowed to cool naturally to obtain the lithium-rich manganese-based cathode material.

[0043] Example 3:

[0044] (1) According to the molar ratio of Ni:Mn:Zr:Fe of 0.5:3:0.1:0.1, NiSO4, MnSO4, Zr(CH3COO)4, and FeSO4 were weighed and dispersed in water to obtain a metal ion solution; oxalic acid was dissolved in ethanol to obtain a precipitant solution. The precipitant solution was added to the metal ion solution and stirred until the reaction was complete. The precipitate was separated by centrifugation and washed successively with deionized water and ethanol, and dried to obtain the precursor;

[0045] (2) According to the molar ratio of Mn in the precursor: Ni in NiO: Li in LiOH·H2O is 3:0.5:6.5, weigh the precursor, NiO and LiOH·H2O, mix them evenly to obtain a mixture;

[0046] (3) The mixture obtained in (2) was placed in a muffle furnace and heated to 300°C at a rate of 1°C / min, and held for 6 h. Then the temperature was increased to 950°C at a rate of 6°C / min, and held for 12 h. After that, it was allowed to cool naturally to obtain the lithium-rich manganese-based cathode material.

[0047] Example 4:

[0048] (1) According to the molar ratio of Ni:Mn:Nd of 0.3:3:0.1, NiSO4, MnSO4, Zr(CH3COO)4, and FeSO4 were weighed and dispersed in water to obtain a metal ion solution; oxalic acid was dissolved in ethanol to obtain a precipitant solution. The precipitant solution was added to the metal ion solution and stirred until the reaction was complete. The precipitate was separated by centrifugation and washed successively with deionized water and ethanol, and dried to obtain the precursor;

[0049] (2) According to the molar ratio of Mn in the precursor: Ni in NiO: Li in LiOH·H2O is 3:0.5:6.5, weigh the precursor, NiO and LiOH·H2O, mix them evenly to obtain a mixture;

[0050] (3) The mixture obtained in (2) is placed in a muffle furnace and heated to 500°C at a rate of 2°C / min, and held at that temperature for 3 hours. Then, the temperature is increased to 850°C at a rate of 3°C / min, and held at that temperature for 24 hours. After that, it is allowed to cool naturally to obtain the lithium-rich manganese-based cathode material.

[0051] Example 5:

[0052] (1) According to the molar ratio of Ni:Mn:Si:Sm of 0.8:3:0.1:0.1, NiSO4, MnSO4, Na2SiO3, and Sm(CH3COO)3 were weighed and dispersed in water to obtain a metal ion solution; sodium oxalate was dissolved in water to obtain a precipitant solution. The precipitant solution was added to the metal ion solution and stirred until the reaction was complete. The precipitate was separated by centrifugation and washed successively with deionized water and ethanol, and dried to obtain the precursor;

[0053] (2) According to the molar ratio of Mn in the precursor: Ni in NiO: Li in LiOH·H2O is 3:0.2:6, weigh the precursor, NiO and LiOH·H2O, mix them evenly to obtain a mixture;

[0054] (3) The mixture obtained in (2) was placed in a muffle furnace and heated to 400°C at a rate of 1°C / min, and held for 5 h. Then the temperature was increased to 950°C at a rate of 5°C / min, and held for 20 h. After that, it was cooled naturally to obtain the lithium-rich manganese-based cathode material.

[0055] Example 6:

[0056] (1) Weigh out Ni(NO3)3, Mn(NO3)3, and Al(NO3)3 according to the molar ratio of Ni:Mn:Al of 0.8:3:0.3, disperse them in water to obtain a metal ion solution; dissolve oxalic acid in ethanol to obtain a precipitant solution. Add the precipitant solution to the metal ion solution and stir until the reaction is complete. Centrifuge the precipitate and wash it successively with deionized water and ethanol, and dry it to obtain the precursor;

[0057] (2) According to the molar ratio of Mn in the precursor: Ni in NiCO3: Li in Li2CO3 being 3:0.2:6, weigh the precursor, NiCO3, and Li2CO3, mix them evenly, and obtain a mixture.

[0058] (3) The mixture obtained in (2) was placed in a muffle furnace and heated to 500°C at a rate of 3°C / min, and held for 10 h. Then the temperature was increased to 850°C at a rate of 6°C / min and held for 12 h. After that, it was allowed to cool naturally to obtain the lithium-rich manganese-based cathode material.

[0059] Example 7:

[0060] (1) According to the molar ratio of Ni:Mn:Eu of 0.9:3:0.1, NiSO4, MnSO4, and Eu2O3 were weighed and dispersed in water to obtain a metal ion solution; sodium carbonate was dissolved in water to obtain a precipitant solution. The precipitant solution was added to the metal ion solution and stirred until the reaction was complete. The precipitate was separated by centrifugation and washed successively with deionized water and ethanol, and dried to obtain the precursor;

[0061] (2) According to the molar ratio of Mn in the precursor: Ni in NiCO3: Li in Li2CO3 of the precursor is 3:0.1:6, weigh the precursor, NiCO3 and Li2CO3, mix them evenly to obtain a mixture;

[0062] (3) The mixture obtained in (2) was placed in a muffle furnace and heated to 400°C at a rate of 1°C / min, and held for 5 h. Then the temperature was increased to 950°C at a rate of 5°C / min, and held for 20 h. After that, it was cooled naturally to obtain the lithium-rich manganese-based cathode material.

[0063] Example 8:

[0064] (1) According to the molar ratio of Ni:Mn:Cu:Ho of 0.5:3:0.2:0.1, NiSO4, MnSO4, CuSO4, and Ho2O3 were weighed and dispersed in water to obtain a metal ion solution; sodium carbonate was dissolved in water to obtain a precipitant solution. The precipitant solution was added to the metal ion solution and stirred until the reaction was complete. The precipitate was separated by centrifugation and washed successively with deionized water and ethanol, and dried to obtain the precursor;

[0065] (2) Weigh the precursor, NiCO3 and Li2CO3 according to the molar ratio of Mn in the precursor, Ni in NiCO3 and Li in Li2CO3 of 3:0.5:6.5, mix them evenly to obtain a mixture;

[0066] (3) The mixture obtained in (2) was placed in a muffle furnace and heated to 350°C at a rate of 2°C / min, and held for 6 h. Then the temperature was increased to 950°C at a rate of 5°C / min and held for 12 h. After that, it was allowed to cool naturally to obtain the lithium-rich manganese-based cathode material.

[0067] Example 9:

[0068] (1) According to the molar ratio of Ni:Mn:Tb:Dy of 0.7:3:0.05:0.05, NiSO4, MnSO4, Tb(NO3)3·5H2O, and Dy(NO3)3·6H2O were weighed and dispersed in water to obtain a metal ion solution; sodium oxalate was dissolved in water to obtain a precipitant solution. The precipitant solution was added to the metal ion solution and stirred until the reaction was complete. The precipitate was separated by centrifugation and washed successively with deionized water and ethanol, and dried to obtain the precursor;

[0069] (2) According to the molar ratio of Mn:NiO in the precursor to Li in Ni:LiOH·H2O is 3:0.3:6, weigh the precursor, NiCO3 and Li2CO3, mix them evenly to obtain a mixture;

[0070] (3) The mixture obtained in (2) was placed in a muffle furnace and heated to 500°C at a rate of 3°C / min, and held for 8 hours. Then the temperature was increased to 900°C at a rate of 4°C / min and held for 16 hours. After that, it was allowed to cool naturally to obtain the lithium-rich manganese-based cathode material.

[0071] Example 10:

[0072] According to the molar ratio of Ni:Mn:Tb:Dy of 0.7:3:0.05:0.05, NiSO4, MnSO4, Tb(NO3)3·5H2O, and Dy(NO3)3·6H2O were weighed and dispersed in water to obtain a metal ion solution; sodium oxalate was dissolved in water to obtain a precipitant solution. The precipitant solution was added to the metal ion solution and stirred until the reaction was complete. The precipitate was centrifuged and washed successively with deionized water and ethanol, and dried to obtain the precursor.

[0073] (2) According to the molar ratio of Mn:NiO in the precursor to Li in Ni:LiOH·H2O is 3:0.3:6, weigh the precursor, NiCO3 and Li2CO3, mix them evenly to obtain a mixture;

[0074] (3) The mixture obtained in (2) is placed in a muffle furnace and heated to 300°C at a rate of 2°C / min, and held at that temperature for 10 h. Then, the temperature is increased to 950°C at a rate of 5°C / min, and held at that temperature for 12 h. After that, it is allowed to cool naturally to obtain the lithium-rich manganese-based cathode material.

[0075] Figure 1 The images show powder X-ray diffraction patterns of a common lithium-rich manganese-based cathode material and the voltage-attenuation-free lithium-rich manganese-based cathode material described in this invention. The diffraction peak shapes and positions of the two materials are essentially the same, indicating that the lithium-rich manganese-based cathode material prepared by the method described in this invention has a conventional layered lattice structure. Specifically, the Ni source is added in two stages during the synthesis process, unlike the commonly used method of adding all the Ni source at once, resulting in a material structure consistent with the original structure.

[0076] Figure 2 This diagram illustrates the discharge specific capacity of a conventional lithium-rich manganese-based cathode material and the voltage-degradation-free lithium-rich manganese-based cathode material described in this invention. The lithium-rich manganese-based cathode material described in this invention exhibits significantly higher capacity retention and voltage retention after 300 charge-discharge cycles compared to the conventional lithium-rich manganese-based cathode material, indicating its superior performance.

[0077] Figure 3 The cell volume changes of ordinary lithium-rich manganese-based cathode materials and the voltage-decrease-free lithium-rich manganese-based cathode material described in this invention are shown during one charge-discharge cycle. The cell volume was obtained by Rietveld refinement of the X-ray diffraction patterns. The lithium-rich manganese-based cathode material described in this invention exhibits smaller cell volume changes during charge-discharge, indicating that the material has a stable crystal lattice structure.

[0078] Figure 4 The images show differential electrochemical mass spectra of a conventional lithium-rich manganese-based cathode material and the voltage-decrease-free lithium-rich manganese-based cathode material described in this invention. Both exhibit the characteristic of releasing oxygen during charging, as seen in the conventional lithium-rich manganese-based cathode material. However, the lithium-rich manganese-based cathode material described in this invention does not release oxygen. This indicates that the redox reaction of lattice oxygen in the material is highly reversible, enabling it to maintain stability while providing capacity.

[0079] The material obtained by this invention can be applied in the field of electric vehicles as a positive electrode material for lithium batteries. The material of this invention has high specific capacity, high capacity retention over long cycles, and virtually no voltage decay. Oxygen release in the material is suppressed, resulting in good safety performance. The synthesis process is simple, and the raw materials used are inexpensive. The material of this invention is suitable for use in high-energy-density, safe, and inexpensive electric vehicle batteries. It should be further noted that the above embodiments of this invention are not intended to limit the scope of protection of this invention, but are merely used to understand the technical concept and technical solution of this invention. Any obvious modifications made to the above embodiments that fall under the second technical concept of this invention should be within the scope of protection of this invention.

Claims

1. A method for preparing a lithium-rich manganese-based cathode material with no voltage decay, characterized in that, A precursor with excess Mn was obtained through co-precipitation. This precursor was then mixed uniformly with Ni and Li sources, followed by sintering to obtain a product with the general chemical formula Li. 1.2 Ni 0.2 Mn 0.6-α A α The specific process steps for O2-rich lithium-manganese-based cathode materials are as follows: (1) Weigh Ni salt, Mn salt and one or more salts or oxides of A, disperse them in water to obtain a metal ion solution; dissolve the precipitant in water or ethanol to obtain a precipitant solution, add the precipitant solution to the metal ion solution, stir until the reaction is complete, centrifuge the precipitate, wash it with deionized water and ethanol in sequence, and dry it to obtain the precursor. (2) Mix the precursor, Ni source and Li source obtained in (1) evenly to obtain a mixture; (3) The mixture obtained in (2) is placed in a muffle furnace for sintering to obtain the lithium-rich manganese-based cathode material; In step (1), the molar ratio of Ni in Ni salt, Mn in Mn salt, and A in A salt or oxide is x:1:y, 0.3 ≤x ≤1, 0.025 ≤y ≤ 0.5; In step (3), the sintering process consists of five processes: heating, constant temperature, heating, constant temperature, and cooling. The heating rate of the first heating process is 1~3℃ / min, the temperature of the first constant temperature process is 300~600℃, and the holding time is 3~10h. The heating rate of the second heating process is 3~6℃ / min, the temperature of the second constant temperature process is 700~1000℃, and the holding time is 10~24h. The cooling process is natural cooling. A is one or more of the elements Fe, Mg, Al, Cu, Cr, Zr, Ti, Sc, Zn, Sn, Si, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Yb, and the content of A in the general chemical formula is 0.005 ≤ α ≤ 0.

1.

2. The method as described in claim 1, characterized in that, In step (1), the Ni salt is one or more of NiSO4, Ni(NO3)2, and NiCl2, the Mn salt is one or more of MnSO4, Mn(NO3)2, and MnCl2, and the salt or oxide of A is FeSO4, Zr(CH3COO)4, TiO2, or MgO.

3. The method as described in claim 1, characterized in that, In step (1), the total metal ion concentration in the metal ion solution is ≥1 mol / L, the charge concentration of the precipitant solution is close to or equal to the total metal ion charge concentration in the metal ion solution, and the precipitant is one of oxalic acid, sodium oxalate or sodium carbonate.

4. The method as described in claim 1, characterized in that, In step (2), the Ni source is one or more of NiO, NiCO3, and Ni(NO3)2, and the Li source is one of LiOH, LiOH·H2O, LiNO3, and Li2CO3.

5. The method as described in claim 1, characterized in that, In step (2), an appropriate amount of Ni source and Li source are added so that the molar ratio of Ni, Mn and Li in the final mixture is 1:3:z, 6 ≤ z ≤ 7. The actual addition ratio of Ni source depends on the molar ratio of Ni salt and Mn salt in step (1).

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