A double-coated lithium-rich manganese-based material and its preparation method, application and battery

Abstract

The present invention discloses a double-coated lithium-rich manganese-based material. The chemical formula of the material is Li x Mn y Ni z M 2‑x‑y‑z S w O 2‑w (0.2‑2) mol% A a B b , wherein M includes any three or more of Mg, Al, and transition metals, S includes PO4 and / or BO3, A includes one or more of Ca, Sr, Ba, and lanthanide metals, and B includes one or more of SO4, PO4, SiO3, SiF6, BF4, and SiO4; 1 < x ≤ 1.5, 0.1 < y ≤ 0.6, 0.02 < z ≤ 0.3, 0 < w ≤ 0.5, 1 ≤ a ≤ 3, and 1 ≤ b ≤ 4. The double-coated lithium-rich manganese-based material prepared by the present invention has fine particles, uniform doping elements, high initial capacity, and excellent cycle stability.

Description

Technical Field

[0001] The present invention specifically relates to a double-coated lithium-rich manganese-based material, a preparation method, an application and a battery. Background Art

[0002] With the increasing demand for energy in modern society and the rapid development of the electric vehicle market, high energy density lithium-ion batteries have received increasing attention from researchers. In current lithium-ion battery systems, there is a capacity mismatch between the positive and negative electrode materials, and the positive electrode capacity is almost an order of magnitude smaller than the anode capacity, which seriously hinders the development of lithium-ion batteries. Among the many lithium-ion battery positive electrode materials, lithium-rich manganese-based positive electrode materials with the chemical formula xLi2MnO3·(1-x)LiTMO2 (TM=Ni, Mn, Co, etc.) are considered to be one of the most promising candidates due to their outstanding specific capacity. Specifically, lithium-rich manganese positive electrode materials have a high specific capacity when a Li + The theoretical capacity can reach 250mAh g -1 Above, if completely out of 1.2Li + , the theoretical capacity can reach about 378mAh g -1 Furthermore, lithium-rich manganese cathode materials, due to their low Co content, offer advantages such as low cost, environmental friendliness, and high thermal stability. These advantages have attracted considerable attention and have led to rapid development in recent years, with many companies now able to produce kilogram-level lithium-rich manganese cathode materials.

[0003] However, despite the outstanding advantages of lithium-rich manganese cathode materials, there are still some unresolved issues, such as low initial Coulombic efficiency, poor rate capacity, and severe voltage decay, which restrict their further practical application. Currently, researchers have prepared lithium-rich manganese cathode materials through methods such as high-temperature solid-phase synthesis, sol-gel method, and molten salt method. By controlling the synthesis conditions and doping treatment, high-performance lithium-rich manganese cathode materials have been prepared, which have broad application prospects in the field of high-energy-density lithium-ion batteries.

[0004] Patent document CN114744186A discloses a method for synthesizing a layered lithium-rich manganese-based composite cathode material. This involves preparing a sodium salt P2-O3 composite phase precursor via sol-gel synthesis, followed by lithium salt ion exchange to obtain an O6-O3 composite phase lithium-ion battery cathode material. While this patent mentions the preparation of multi-cation-doped lithium-rich manganese-based materials via sol-gel-ion exchange, it does not address lithium-rich manganese-based materials modified by polyanion doping, nor does it address double-coating structures. Furthermore, literature suggests that incorporating polyanions into the crystal lattice can mitigate oxygen instability by utilizing strong covalent bonds between anions and oxygen, thereby reducing oxygen loss that may occur at high voltages (Huang, Y. et al. Integrated rocksalt–polyanion cathodes with excess lithium and stabilized cycling. Nat Energy (2024).). However, this document not only fails to address the impact of the synergistic combination of five or more metals and polyanions on the performance of lithium-rich manganese-based materials, but also fails to address double-coating structures. In addition, although polyanion co-doped lithium-rich manganese cathode materials and high-entropy lithium-rich manganese cathode materials are very common, there is no prior art that discloses that polyanions can be doped inside the high-entropy lithium-rich manganese lattice while also in situ covering the surface of the material to form a double coating layer. Summary of the Invention

[0005] The technical problem solved by the present invention is to overcome the shortcomings of existing lithium-rich manganese-based cathode materials in practical applications, such as low initial Coulombic efficiency, poor rate capacity, and severe voltage decay. The present invention provides a double-coated lithium-rich manganese-based material, preparation method, application, and battery. The double-coated lithium-rich manganese-based material prepared by the present invention has fine particles, uniform doping elements, and complete coating; the preparation method is simple and low-cost; and when used in the preparation of lithium-ion batteries, it exhibits high initial capacity, excellent cycle stability, and excellent electrochemical performance at high rates.

[0006] The present invention provides a double-coated lithium-rich manganese-based material, the chemical formula of which is Li x Mn y Ni z M 2-x-y-z S w O 2-w ·A a B b , part of the anion S enters the interior of the lattice, and the other part of the anion S forms the first coating layer in the form of metal salts and covers the surface of the material, while A a B bThe second coating layer is formed in situ on the surface of the first coating layer. The present invention prepares the sodium salt precursor by the sol-gel method and ion-exchanges it into a phase. When preparing the lithium-rich manganese material, polyanions are doped and A is generated in situ during the ion exchange process. a B b , which can effectively improve the electrochemical performance of lithium-rich manganese materials. The sol-gel-ion exchange method will assist in the doping of large-radius metal ions and polyanions that are difficult to achieve with ordinary lithium battery positive electrode materials, so that the doped ions can evenly enter the lattice structure and generate A in situ. a B b The coating layer produces a never-before-seen polyanion co-doped double-coated lithium-rich manganese material with fine particles and uniform doping elements. Mechanistically, some polyanions enter the crystal lattice to mitigate structural damage during cycling, while others coat the particle surface in situ, expanding lithium-ion transmission channels and protecting the material from electrolyte damage. The intermingling of high-entropy metal ions in the metal layer and their occupation of the lithium-ion layer also inhibit the migration of lithium ions to the TM layer during cycling, effectively preventing voltage decay. Metal ions and anions with larger radii that have difficulty entering the crystal lattice are generated in situ on the material surface as metal salts during ion exchange, expanding lithium-ion channels, isolating the electrolyte from the material, mitigating irreversible phase transitions, and stabilizing the layered structure.

[0007] The present invention solves the above technical problems through the following technical solutions:

[0008] The present invention provides a double-coated lithium-rich manganese-based material, the chemical formula of which is Li x Mn y Ni z M 2-x-y-z S w O 2-w (0.2-2) mol% A a B b , wherein M includes any three or more of Mg, Al and transition metals, S includes PO4 and / or BO3, A includes one or more of Ca, Sr, Ba and lanthanide metals, and B includes one or more of SO4, PO4, SiO3, SiF6, BF4 and SiO4; 1<x≤1.5, 0.1<y≤0.6, 0.02<z≤0.3, 0<w≤0.5, 1≤a≤3, 1≤b≤4.

[0009] In the present invention, the mol% generally refers to A a B b With Li x Mn y Ni z M 2-x-y-z S w O2-w The mole percentage of

[0010] In the present invention, preferably, the internal Li x Mn y Ni z M 2-x-y-z S w O 2-w In the present invention, part of the polyanion S is located inside the crystal lattice of the material, and part of the polyanion S forms a coating layer in the form of metal salt and covers the surface of the material.

[0011] In the present invention, preferably, in the double-coated lithium-rich manganese-based material, A a B b Coated in Li x Mn y Ni z M 2-x-y- z S w O 2-w surface.

[0012] In the present invention, the double-coated lithium-rich manganese-based material preferably has a double coating layer, part of the polyanion S is located inside the material lattice, and part of the polyanion S forms a first coating layer in the form of a metal salt coated on the surface of the material, and A a B b Then, a second coating layer is in-situ generated on the surface of the first coating layer.

[0013] In the present invention, the transition metal preferably includes one or more of Sc, Ti, V, Cr, Fe, Co, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd and Cd.

[0014] In the present invention, the lanthanide metal preferably includes one or more of La, Ce, Pr, Nd, Pm and Sm.

[0015] In the present invention, in the chemical formula, preferably, 1<x≤1.3, for example, 1.16 or 1.18.

[0016] In the present invention, in the chemical formula, preferably, 0.4<y≤0.6, for example, 0.54.

[0017] In the present invention, in the chemical formula, preferably, 0.03<z≤0.2, such as 0.06, 0.09 or 0.11.

[0018] In the present invention, in the chemical formula, preferably, 0<w≤0.1, such as 0.04, 0.06 or 0.08.

[0019] In the present invention, in the chemical formula, A a Bb The molar ratio is preferably (0.2-1) mol%, such as 0.5 mol%, 0.8 mol% or 1 mol%.

[0020] In a specific embodiment, the M is Mg, Co, Al and Cu.

[0021] In a specific embodiment, the S is PO4 and BO3.

[0022] In a specific embodiment, the A a B b It is BaSO4 or Ba3(PO4)2.

[0023] In a specific embodiment, the chemical formula is:

[0024] Li 1.18 Mg 0.02 Mn 0.54 Ni 0.11 Co 0.11 Al 0.02 Cu 0.02 (PO4) 0.02 (BO3) 0.02 O 1.96 0.5 mol% BaSO4, Li 1.18 Mg 0.02 Mn 0.54 Ni 0.11 Co 0.09 Al 0.04 Cu 0.02 (PO4) 0.04 (BO3) 0.02 O 1.94 0.5 mol% BaSO4, Li 1.16 Mg 0.04 Mn 0.54 Ni 0.09 Co 0.09 Al 0.04 Cu 0.04 (PO4) 0.02 (BO3) 0.04 O 1.94 1 mol% BaSO4, Li 1.18 Mg 0.02 Mn 0.54 Ni 0.06 Co 0.09 Al 0.04 Cu 0.07 (PO4) 0.04 (BO3) 0.04 O 1.92 1 mol% BaSO4, Li 1.18 Mg0.02 Mn 0.54 Ni 0.06 Co 0.06 Al 0.07 Cu 0.07 (PO4) 0.04 (BO3) 0.04 O 1.92 ·1 mol% BaSO4.

[0025] In the present invention, the double-coated lithium-rich manganese-based material can have a first-cycle discharge capacity of 270-320 mAh g at 0.1C and within a voltage range of 2-4.8V. –1 , preferably 280-310mAh g –1 .

[0026] In the present invention, the double-coated lithium-rich manganese-based material can have a first-cycle discharge capacity of 340-400 mAh g at 0.1C and in a voltage range of 1.5-4.8V. –1 , preferably 360-380mAh g –1 .

[0027] In the present invention, the double-coated lithium-rich manganese-based material can have a first-cycle discharge capacity of 400-480 mAh g at 0.1C and in a voltage range of 1-4.8V. –1 , preferably 420-440mAh g –1 .

[0028] In the present invention, the capacity retention rate of the double-coated lithium-rich manganese-based material after 200 cycles at a current of 1C is preferably greater than 70%, and more preferably greater than 90%.

[0029] The present invention also provides a method for preparing the double-coated lithium-rich manganese-based material, which comprises the following steps:

[0030] (1) heating a mixed solution containing a lithium source, a sodium source, a manganese source, a nickel source, an M source, an S source, a solvent, and a complexing agent to form a gel, and then calcining the gel to obtain a sodium salt precursor;

[0031] (2) calcining and washing the mixture of the sodium salt precursor, lithium salt, source A and source B to obtain the double-coated lithium-rich manganese-based material.

[0032] In step (1), the chemical formula of the sodium salt precursor is generally Na x1 Li x-x1 Mn y Ni z M 2-x-y-z S w O 2-wThe meaning and range of each letter are the same as above, wherein 0.9<x1<1.1, preferably 0.95<x1<1.05, for example 1.0.

[0033] In step (1), the amount of the lithium source, sodium source, manganese source, nickel source, M source, and S source can be added in a stoichiometric ratio according to the chemical formula of the sodium salt precursor. According to conventional practice in the art, the amount of the lithium source is generally 1-1.1 times the theoretical addition amount, for example, 1.05 times.

[0034] In step (1), the lithium source is generally a lithium salt soluble in the solvent, preferably including one or more of lithium chloride, lithium bromide, lithium iodide, lithium nitrate, lithium acetate, lithium carbonate, lithium phosphate and lithium borate, such as lithium acetate.

[0035] In step (1), the sodium source is generally a sodium salt soluble in the solvent, preferably including one or more of sodium acetate, sodium nitrate and sodium chloride.

[0036] In step (1), the manganese source is generally a manganese salt soluble in the solvent, preferably including one or more of manganese acetate, manganese nitrate and manganese chloride.

[0037] In step (1), the nickel source is generally a nickel salt soluble in the solvent, preferably including one or more of nickel acetate, nickel nitrate and nickel chloride.

[0038] In step (1), the M source may be one or more of acetate, nitrate and chloride of the corresponding metal.

[0039] In a specific embodiment, the M source is magnesium acetate, cobalt acetate tetrahydrate, aluminum acetate and copper acetate monohydrate.

[0040] In step (1), the S source may be a salt or acid containing a corresponding anion, for example, one or more of lithium phosphate, lithium borate, ammonium phosphate and boric acid.

[0041] In a specific embodiment, the S source is ammonium phosphate and boric acid.

[0042] In step (1), the solvent may be one or more of deionized water, isopropyl alcohol, ethylene glycol, anhydrous ethanol, dimethylformamide and acetone.

[0043] In step (1), the sum of the mass concentrations of the lithium source, the sodium source, the manganese source, the nickel source, the M source, and the S source can be conventional in the art, generally (0.1-0.5) g / mL, preferably (0.2-0.4) g / mL, for example 0.29 g / mL, 0.3 g / mL, or 0.4 g / mL.

[0044] In step (1), the complexing agent may be one or more of citric acid, maleic acid, glycine, ethyl acetate, ethanolamine and ethylenediaminetetraacetic acid.

[0045] In step (1), the amount of the complexing agent is generally 0.5-2 times the sum of the molar amounts of all metal ions in the manganese source, the nickel source and the M source, preferably 1-2 times, for example 1 time or 1.5 times.

[0046] In step (1), the mixed solution is preferably prepared by adding the lithium source, the sodium source, the manganese source, the nickel source, the M source and the S source to the solvent, then adding the complexing agent, and stirring at room temperature until completely dissolved.

[0047] In step (1), the heating temperature may be 60-150°C, preferably 70-100°C, for example 80°C. The heating time may be 6-24 hours, preferably 10-18 hours, for example 14 hours. The heating is preferably carried out under stirring. The stirring speed may be 100-500 rpm, preferably 200-300 rpm, for example 250 rpm.

[0048] In step (1), the gel is generally dried before calcination. The drying method can be conventional in the art, such as oven drying. The drying temperature can be 100-150°C, for example 120°C.

[0049] In step (1), the calcination is generally performed in a muffle furnace. The calcination temperature may be 700-1000°C, for example, 900°C or 1000°C. The calcination time may be 8-15 hours, for example, 12 hours. The temperature may be raised to the calcination temperature at a rate of 1-10°C / min. The cooling rate after calcination may be 1-10°C / min.

[0050] In step (2), the lithium salt may include one or more of lithium chloride, lithium bromide, lithium iodide, lithium nitrate, lithium acetate, lithium carbonate, lithium phosphate and lithium borate.

[0051] In step (2), A and B have the same meanings as in the aforementioned chemical formula and are not repeated here.

[0052] In step (2), the A source may be a salt containing metal A ions, such as acetate and / or nitrate.

[0053] In step (2), the B source may be a salt or acid containing a corresponding anion, such as one or more of ammonium phosphate, ammonium sulfate, lithium phosphate, lithium sulfate, lithium silicate, lithium borate, lithium hexafluorosilicate, lithium tetrafluoroborate, lithium metasilicate and boric acid.

[0054] In a specific embodiment, the source A is barium acetate and the source B is ammonium sulfate.

[0055] In step (2), the molar ratio of the sodium salt precursor to the lithium salt may be 1:(1.5-3), for example, 1:2 or 1:2.5.

[0056] In step (2), the molar ratio of the A source to the sodium salt precursor may be 0.2%-2%, preferably 0.2%-1%, such as 0.5%, 0.8% or 1%.

[0057] In step (2), the amounts of the A ions in the A source and the B ions in the B source are generally added in a stoichiometric ratio according to the chemical formula.

[0058] In step (2), the mixture is generally ground before calcination.

[0059] In step (2), the calcination is generally performed in a muffle furnace. The calcination temperature is generally higher than the melting point of the lithium salt, preferably 10°C above the melting point of the lithium salt and below 200°C. The calcination time can be 3-10 hours, preferably 4-6 hours, for example 5 hours.

[0060] When the lithium salt is lithium chloride, the calcination temperature may be 620-800°C, such as 650°C or 700°C.

[0061] In step (2), the solvent used for washing can be deionized water and / or a polar organic solvent. The polar organic solvent can be one or more of methanol, ethanol, propanol, ethylene glycol, glycerol, ethylenediamine, acetonitrile, DMF, and DMSO. The washing method can be suction filtration. In order to better remove impurity ions, the calcined product can also be soaked in the solvent for a period of time and then suction filtered.

[0062] In step (2), according to conventional practice in the art, the washing is generally followed by drying. The drying method can be conventional in the art, such as oven drying. The drying temperature can be 60-150°C, preferably 70-100°C, for example 80°C. The drying time can be 2-12 hours, preferably 6-10 hours, for example 8 hours.

[0063] The present invention also provides a double-coated lithium-rich manganese-based material prepared by the above-mentioned preparation method.

[0064] The present invention also provides an application of the double-coated lithium-rich manganese-based material as described above in a lithium-ion battery.

[0065] The present invention also provides a lithium-ion battery, which includes the double-coated lithium-rich manganese-based material as described above.

[0066] In the present invention, the double-coated lithium-rich manganese-based material is preferably used as a positive electrode material in a lithium-ion battery.

[0067] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0068] The reagents and raw materials used in the present invention are commercially available.

[0069] The positive progress effect of the present invention is:

[0070] The double-coated lithium-rich manganese-based material prepared by the present invention has fine particles and uniform doping elements; the preparation method is simple and the cost is low; when preparing lithium-ion batteries, it has high initial capacity, excellent cycle stability and excellent electrochemical performance at high rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 This is an SEM image of the double-coated lithium-rich manganese-based material prepared in Example 1;

[0072] Figure 2 This is the XRD pattern of the double-coated lithium-rich manganese-based material prepared in Example 1;

[0073] Figure 3 HRTEM images of lithium-rich manganese-based materials prepared in Example 1 and Comparative Examples 1-3;

[0074] Figure 4 This is a 2-4.8V first cycle capacity performance diagram of the double-coated lithium-rich manganese-based material prepared in Example 1;

[0075] Figure 5 This is a first cycle capacity performance diagram of the double-coated lithium-rich manganese-based material prepared in Example 1 at 1.5-4.8V;

[0076] Figure 6 This is a first cycle capacity performance diagram of the double-coated lithium-rich manganese-based material prepared in Example 1 at 1.0-4.8V;

[0077] Figure 7 This is a cycling performance diagram of the double-coated lithium-rich manganese-based material prepared in Example 1 at 1C (2-4.8V);

[0078] Figure 8 This is a cycling performance diagram of the double-coated lithium-rich manganese-based material prepared in Example 1 at 0.1C (2-4.8V);

[0079] Figure 9 This is the first cycle capacity performance diagram of the double-coated lithium-rich manganese-based material prepared in Example 2-4 at 0.1C (2-4.8V);

[0080] Figure 10This is a cycle performance diagram of the double-coated lithium-rich manganese-based material prepared in Example 2-4 at 1C (2-4.8V);

[0081] Figure 11 The first cycle capacity performance diagram of the lithium-rich manganese material prepared in Comparative Examples 1-3 at 0.1C (2-4.8V);

[0082] Figure 12 This is a graph showing the cycle performance of the lithium-rich manganese material prepared in Comparative Examples 1-3 at 1C (2-4.8V). DETAILED DESCRIPTION

[0083] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0084] Example 1

[0085] Double-coated lithium-rich manganese-based material Li 1.18 Mg 0.02 Mn 0.54 Ni 0.11 Co 0.11 Al 0.02 Cu 0.02 (PO4) 0.02 (BO3) 0.02 O 1.96 0.5 mol% BaSO4 preparation:

[0086] S1, weigh 50 mmol of sodium acetate, 9.45 mmol of lithium acetate, 1 mmol of magnesium acetate, 27 mmol of manganese acetate, 5.5 mmol of nickel acetate tetrahydrate, 5.5 mmol of cobalt acetate tetrahydrate, 1 mmol of aluminum acetate, 1 mmol of copper acetate monohydrate, 1 mmol of ammonium phosphate, and 1 mmol of boric acid, dissolve in 50 mL of water, and add 61.5 mmol of citric acid monohydrate, and stir at room temperature to completely dissolve;

[0087] S2, the solution was stirred at 80 ° C and 250 rpm for 14 hours to form a gel; dried at 120 ° C for 12 hours to obtain a dry gel; the dry gel was placed in a muffle furnace and heated to 900 ° C at a heating rate of 5 ° C / min, and kept at this temperature for 12 hours, and then cooled to room temperature at a cooling rate of 5 ° C / min to obtain the sodium salt precursor NaLi 0.18 Mg 0.02 Mn 0.54 Ni 0.11 Co 0.11 Al 0.02 Cu 0.02 (PO4) 0.02 (BO3)0.02 O 1.96 ;

[0088] S3, weigh 5 mmol of sodium salt precursor, 12.5 mmol of lithium chloride, 0.025 mmol of barium acetate, and 0.025 mmol of ammonium sulfate, grind and mix, and transfer to a muffle furnace and calcine at 650 °C for 5 h;

[0089] S4, filtering the calcined product with ethanol and then drying it at a temperature of 80° C. for 8 hours to obtain a double-coated lithium-rich manganese-based material.

[0090] Example 2

[0091] Double-coated lithium-rich manganese-based material Li 1.18 Mg 0.02 Mn 0.54 Ni 0.11 Co 0.09 Al 0.04 Cu 0.02 (PO4) 0.04 (BO3) 0.02 O 1.94 0.5 mol% BaSO4 preparation:

[0092] S1, weigh 50 mmol of sodium acetate, 9.45 mmol of lithium acetate, 1 mmol of magnesium acetate, 27 mmol of manganese acetate, 5.5 mmol of nickel acetate tetrahydrate, 4.5 mmol of cobalt acetate tetrahydrate, 2 mmol of aluminum acetate, 1 mmol of copper acetate monohydrate, 2 mmol of ammonium phosphate, and 1 mmol of boric acid, dissolve in 50 mL of water, and add 61.5 mmol of citric acid monohydrate, and stir at room temperature to completely dissolve;

[0093] S2, the solution was stirred at 80 ° C and 250 rpm for 14 hours to form a gel; dried at 120 ° C for 12 hours to obtain a dry gel; the dry gel was placed in a muffle furnace and heated to 900 ° C at a heating rate of 5 ° C / min, and kept at this temperature for 12 hours, and then cooled to room temperature at a cooling rate of 5 ° C / min to obtain the sodium salt precursor NaLi 0.18 Mg 0.02 Mn 0.54 Ni 0.11 Co 0.09 Al 0.04 Cu 0.02 (PO4) 0.04 (BO3) 0.02 O 1.94 ;

[0094] S3, weigh 5 mmol of sodium salt precursor, 12.5 mmol of lithium chloride, 0.025 mmol of barium acetate, and 0.025 mmol of ammonium sulfate, grind and mix, and transfer to a muffle furnace and calcine at 650 °C for 5 h;

[0095] S4, filtering and drying the calcined product with ethanol at a drying temperature of 80° C. for 8 h to obtain a double-coated lithium-rich manganese-based material.

[0096] Example 3

[0097] Double-coated lithium-rich manganese-based material Li 1.16 Mg 0.04 Mn 0.54 Ni 0.09 Co 0.09 Al 0.04 Cu 0.04 (PO4) 0.02 (BO3) 0.04 O 1.94 1 mol% BaSO4 preparation:

[0098] S1, weigh 50 mmol of sodium acetate, 8.4 mmol of lithium acetate, 2 mmol of magnesium acetate, 27 mmol of manganese acetate, 4.5 mmol of nickel acetate tetrahydrate, 4.5 mmol of cobalt acetate tetrahydrate, 2 mmol of aluminum acetate, 2 mmol of copper acetate monohydrate, 1 mmol of ammonium phosphate, and 2 mmol of boric acid, dissolve in 50 mL of water, and add 63 mmol of citric acid monohydrate, stirring at room temperature to completely dissolve;

[0099] S2, the solution was stirred at 80 ° C and 250 rpm for 14 hours to form a gel; dried at 120 ° C for 12 hours to obtain a dry gel; the dry gel was placed in a muffle furnace and heated to 900 ° C at a heating rate of 5 ° C / min, and kept at this temperature for 12 hours, and then cooled to room temperature at a cooling rate of 5 ° C / min to obtain the sodium salt precursor NaLi 0.16 Mg 0.04 Mn 0.54 Ni 0.09 Co 0.09 Al 0.04 Cu 0.04 (PO4) 0.02 (BO3) 0.04 O 1.94 ;

[0100] S3, weigh 5 mmol of sodium salt precursor, 12.5 mmol of lithium chloride, 0.05 mmol of barium acetate, and 0.05 mmol of ammonium sulfate, grind and mix, and transfer to a muffle furnace and calcine at 650 °C for 5 h;

[0101] S4, filtering and drying the calcined product with ethanol at a drying temperature of 80° C. for 8 h to obtain a double-coated lithium-rich manganese-based material.

[0102] Example 4

[0103] Double-coated lithium-rich manganese-based material Li 1.18 Mg 0.02 Mn 0.54 Ni 0.06 Co 0.09 Al 0.04 Cu 0.07 (PO4) 0.04 (BO3) 0.04 O 1.92 1 mol% BaSO4 preparation:

[0104] S1, weigh 50 mmol of sodium acetate, 9.45 mmol of lithium acetate, 1 mmol of magnesium acetate, 27 mmol of manganese acetate, 3 mmol of nickel acetate tetrahydrate, 4.5 mmol of cobalt acetate tetrahydrate, 2 mmol of aluminum acetate, 3.5 mmol of copper acetate monohydrate, 2 mmol of ammonium phosphate, and 2 mmol of boric acid, dissolve in 50 mL of water, and add 61.5 mmol of citric acid monohydrate, and stir at room temperature to completely dissolve;

[0105] S2, the solution was stirred at 80 ° C and 250 rpm for 14 hours to form a gel; dried at 120 ° C for 12 hours to obtain a dry gel; the dry gel was placed in a muffle furnace and heated to 900 ° C at a heating rate of 5 ° C / min, and kept at this temperature for 12 hours, and then cooled to room temperature at a cooling rate of 5 ° C / min to obtain a sodium salt precursor, NaLi 0.18 Mg 0.02 Mn 0.54 Ni 0.06 Co 0.09 Al 0.04 Cu 0.07 (PO4) 0.04 (BO3) 0.04 O 1.92 ;

[0106] S3, weigh 5 mmol of sodium salt precursor, 12.5 mmol of lithium chloride, 0.05 mmol of barium acetate, and 0.05 mmol of ammonium sulfate, grind and mix, and transfer to a muffle furnace and calcine at 650 °C for 5 h;

[0107] S4, filtering and drying the calcined product with ethanol at a drying temperature of 80° C. for 8 h to obtain a double-coated lithium-rich manganese-based material.

[0108] Example 5

[0109] Double-coated lithium-rich manganese-based material Li1.18 Mg 0.02 Mn 0.54 Ni 0.06 Co 0.06 Al 0.07 Cu 0.07 (PO4) 0.04 (BO3) 0.04 O 1.92 1 mol% BaSO4 preparation:

[0110] S1, weigh 50 mmol of sodium acetate, 9.45 mmol of lithium acetate, 1 mmol of magnesium acetate, 27 mmol of manganese acetate, 3 mmol of nickel acetate tetrahydrate, 3 mmol of cobalt acetate tetrahydrate, 3.5 mmol of aluminum acetate, 3.5 mmol of copper acetate monohydrate, 2 mmol of ammonium phosphate, and 2 mmol of boric acid, dissolve in 50 mL of water, and add 61.5 mmol of citric acid monohydrate, and stir at room temperature to completely dissolve;

[0111] S2, the solution was stirred at 80 ° C and 250 rpm for 14 hours to form a gel; dried at 120 ° C for 12 hours to obtain a dry gel; the dry gel was placed in a muffle furnace and heated to 900 ° C at a heating rate of 5 ° C / min, and kept at this temperature for 12 hours, and then cooled to room temperature at a cooling rate of 5 ° C / min to obtain the sodium salt precursor NaLi 0.18 Mg 0.02 Mn 0.54 Ni 0.06 Co 0.06 Al 0.07 Cu 0.07 (PO4) 0.04 (BO3) 0.04 O 1.92 ;

[0112] S3, weigh 5 mmol of sodium salt precursor, 12.5 mmol of lithium chloride, 0.05 mmol of barium acetate, and 0.05 mmol of ammonium sulfate, grind and mix, and transfer to a muffle furnace and calcine at 650 °C for 5 h;

[0113] S4, filtering and drying the calcined product with ethanol at a drying temperature of 80° C. for 8 h to obtain a double-coated lithium-rich manganese-based material.

[0114] Comparative Example 1

[0115] Lithium-rich manganese-based materials 1.2 Mn 0.54 Ni 0.13 Co 0.13 O2 preparation:

[0116] S1, weigh 50 mmol of sodium acetate, 10.5 mmol of lithium acetate, 27 mmol of manganese acetate, 6.5 mmol of nickel acetate tetrahydrate, and 6.5 mmol of cobalt acetate tetrahydrate, dissolve them in 50 ml of water, and add 60 mmol of citric acid monohydrate, stirring at room temperature to completely dissolve;

[0117] S2, the solution was stirred at 80 ° C and 250 rpm for 14 hours to form a gel; dried at 120 ° C for 12 hours to obtain a dry gel; the dry gel was placed in a muffle furnace and heated to 900 ° C at a heating rate of 5 ° C / min, and kept at this temperature for 12 hours, and then cooled to room temperature at a cooling rate of 5 ° C / min to obtain the sodium salt precursor NaLi 0.2 Mn 0.54 Ni 0.13 Co 0.13 O2;

[0118] S3, weigh 5 mmol of sodium salt precursor and 12.5 mmol of lithium chloride, grind and mix, transfer to a muffle furnace and calcine at 650 °C for 5 h;

[0119] S4, the calcined product is filtered and dried with ethanol at a drying temperature of 80° C. for 8 h to obtain the final product.

[0120] Comparative Example 2

[0121] Lithium-rich manganese-based materials 1.18 Mg 0.02 Mn 0.54 Ni 0.11 Co 0.11 Al 0.02 Cu 0.02 (PO4) 0.02 (BO3) 0.02 O 1.96 preparation:

[0122] S1, weigh 50 mmol of sodium acetate, 9.45 mmol of lithium acetate, 1 mmol of magnesium acetate, 27 mmol of manganese acetate, 5.5 mmol of nickel acetate tetrahydrate, 5.5 mmol of cobalt acetate tetrahydrate, 1 mmol of aluminum acetate, 1 mmol of copper acetate monohydrate, 1 mmol of ammonium phosphate, and 1 mmol of boric acid, dissolve in 50 mL of water, and add 61.5 mmol of citric acid monohydrate, and stir at room temperature to completely dissolve;

[0123] S2, the solution was stirred at 80 ° C and 250 rpm for 14 hours to form a gel; dried at 120 ° C for 12 hours to obtain a dry gel; the dry gel was placed in a muffle furnace and heated to 900 ° C at a heating rate of 5 ° C / min, and kept at this temperature for 12 hours, and then cooled to room temperature at a cooling rate of 5 ° C / min to obtain the sodium salt precursor NaLi 0.18Mg 0.02 Mn 0.54 Ni 0.11 Co 0.11 Al 0.02 Cu 0.02 (PO4) 0.02 (BO3) 0.02 O 1.96 ;

[0124] S3, weigh 5 mmol of sodium salt precursor and 12.5 mmol of lithium chloride, grind and mix, transfer to a muffle furnace and calcine at 650 °C for 5 h;

[0125] S4, the calcined product is filtered and dried with ethanol at a drying temperature of 80° C. for 8 h to obtain the final product.

[0126] Comparative Example 3

[0127] Lithium-rich manganese-based materials 1.18 Mg 0.02 Mn 0.54 Ni 0.11 Co 0.11 Al 0.02 Cu 0.02 O2 preparation:

[0128] S1, weigh 50 mmol of sodium acetate, 9.45 mmol of lithium acetate, 1 mmol of magnesium acetate, 27 mmol of manganese acetate, 5.5 mmol of nickel acetate tetrahydrate, 5.5 mmol of cobalt acetate tetrahydrate, 1 mmol of aluminum acetate, and 1 mmol of copper acetate monohydrate, dissolve them in 50 ml of water, and add 61.5 mmol of citric acid monohydrate, and stir at room temperature to completely dissolve;

[0129] S2, the solution was stirred at 80 ° C and 250 rpm for 14 hours to form a gel; dried at 120 ° C for 12 hours to obtain a dry gel; the dry gel was placed in a muffle furnace and heated to 900 ° C at a heating rate of 5 ° C / min, and kept at this temperature for 12 hours, and then cooled to room temperature at a cooling rate of 5 ° C / min to obtain the sodium salt precursor NaLi 0.18 Mg 0.02 Mn 0.54 Ni 0.11 Co 0.11 Al 0.02 Cu 0.0 2O2;

[0130] S3, weigh 5 mmol of sodium salt precursor and 12.5 mmol of lithium chloride, grind and mix, transfer to a muffle furnace and calcine at 650 °C for 5 h;

[0131] S4, the calcined product is filtered and dried with ethanol at a drying temperature of 80° C. for 8 h to obtain the final product.

[0132] Comparative Example 4

[0133] Lithium-rich manganese-based materials 1.2 Mn 0.54 Ni 0.13 Co 0.13 (PO4) 0.02 (BO3) 0.02 O 1.96 preparation:

[0134] S1, weigh 50 mmol of sodium acetate, 10.5 mmol of lithium acetate, 27 mmol of manganese acetate, 6.5 mmol of nickel acetate tetrahydrate, 6.5 mmol of cobalt acetate tetrahydrate, 1 mmol of ammonium phosphate, and 1 mmol of boric acid, dissolve in 50 ml of water, and add 60 mmol of citric acid monohydrate, stirring at room temperature to completely dissolve;

[0135] S2, the solution was stirred at 80 ° C and 250 rpm for 14 hours to form a gel; dried at 120 ° C for 12 hours to obtain a dry gel; the dry gel was placed in a muffle furnace and heated to 900 ° C at a heating rate of 5 ° C / min, and kept at this temperature for 12 hours, and then cooled to room temperature at a cooling rate of 5 ° C / min to obtain the sodium salt precursor NaLi 0.2 Mn 0.54 Ni 0.13 Co 0.13 (PO4) 0.02 (BO3) 0.02 O 1.96 ;

[0136] S3, weigh 5 mmol of sodium salt precursor and 12.5 mmol of lithium chloride, grind and mix, transfer to a muffle furnace and calcine at 650 °C for 5 h;

[0137] S4, the calcined product is filtered and dried with ethanol at a drying temperature of 80° C. for 8 h to obtain the final product.

[0138] Effect embodiment

[0139] (1) SEM, XRD characterization and element content characterization

[0140] Figure 1 This is a SEM image of the double-coated lithium-rich manganese-based material in Example 1. The image shows uniform, nanoscale particle size. Small particles facilitate lithium ion diffusion during charge and discharge, improving electrochemical performance.

[0141] Figure 2This is the XRD of the double-coated lithium-rich manganese-based material in Example 1. It can be seen from the figure that the sample is a mixture of standard LiMO2 phase and Li2MnO3 phase, which is consistent with the XRD peak value of lithium-rich manganese material and has no unnecessary peaks.

[0142] from Figure 3 It can be seen that the barium sulfate-coated phosphate and borate co-doped lithium-rich manganese-based high-entropy positive electrode material in Example 1 has a clear double-coating structure, in which the inner layer is a phosphate and borate amorphous coating, and the outer layer is a barium sulfate coating. Its lattice spacing conforms to the (001) interplanar spacing of barium sulfate crystals, and they are all formed in situ. Compared with Comparative Example 1, Comparative Example 2 and Comparative Example 3 have larger interplanar spacings, indicating that the doping of metal ions and polyanions can expand the interplanar spacing. The increase in interplanar spacing in Comparative Example 2 is greater than that in Comparative Example 3, indicating that the polyanion enters the lattice. At the same time, it can be seen that the surface of Comparative Example 2 has a clear amorphous coating layer, which is formed in situ by the polyanion on the surface.

[0143] The phosphate and borate co-doped high entropy lithium-rich manganese-based cathode material Li prepared in Comparative Example 2 was prepared by ICP. 1.18 Mg 0.02 Mn 0.54 Ni 0.11 Co 0.11 Al 0.02 Cu 0.02 (PO4) 0.02 (BO3) 0.02 O 1.96 An analysis was conducted, and the elemental analysis results are shown in Table 1. It can be seen from Table 1 that the atomic ratio obtained by ICP test is consistent with the raw material ratio input into the experiment and the designed chemical formula.

[0144] Table 1

[0145] element Mass concentration (mg / L) Atomic ratio Li concentration 6.94 0.580 Mn concentration 53.94 0.260 Ni concentration 58.69 0.055 Mg concentration 24.31 0.010 Co concentration 58.93 0.055 Al concentration 26.98 0.010 Cu concentration 63.59 0.010 P concentration 30.74 0.010 B concentration 10.81 0.010

[0146] (2) Electrochemical performance test

[0147] The electrochemical properties of the final products prepared in the above embodiments and comparative examples were evaluated using CR2032 button batteries.

[0148] The final product materials prepared in Examples 1-5 and Comparative Examples 1-4, SuperP, and polyvinylidene fluoride (PVDF) were uniformly mixed in a mass ratio of 8:1:1 to prepare an electrode slurry in NMP solvent. The electrode slurry was then evenly coated on aluminum foil using a coater and dried overnight in a vacuum environment at 120°C. Finally, cathode sheets with a diameter of 13 mm were punched on a tablet press, with a loading of approximately 2 to 3 mg cm -2A CR2032 coin-type half-cell was assembled using the prepared electrode as the positive electrode, pure lithium as the counter electrode, Celgard 2500 as the separator, and 1.0 M LiPF6 in EC:DMC:EMC = 1:1:1 Vol% + 5 wt% FEC (i.e., the volume ratio of EC:DMC:EMC is 1:1:1, and the percentage of FEC in the total mass of the electrolyte is 5%). The resulting battery was subjected to charge and discharge tests on an electrochemical workstation, with 1C = 250 mAh g -1 The test results are shown in Figure 4-Figure 12 and Table 2:

[0149] Table 2

[0150] sample Voltage range First cycle discharge specific capacity 200-cycle capacity retention rate Example 1 2-4.8V <![CDATA[308mAhg -1 ]]> 96.8％ Example 2 2-4.8V <![CDATA[281mAhg -1 ]]> 71.6％ Example 3 2-4.8V <![CDATA[291mAhg -1 ]]> 94.3％ Example 4 2-4.8V <![CDATA[289mAhg -1 ]]> 85.5％ Example 5 2-4.8V <![CDATA[287mAhg -1 ]]> 73.5％ Comparative Example 1 2-4.8V <![CDATA[237mAhg -1 ]]> 76.9％ Comparative Example 2 2-4.8V <![CDATA[265mAhg -1 ]]> 66.7％ Comparative Example 3 2-4.8V <![CDATA[234mAhg -1 ]]> 82.8％ Comparative Example 4 2-4.8V <![CDATA[253mAhg -1 ]]> 78.4％

[0151] According to the data of Examples 1-5, the prepared double-coated lithium-rich manganese-based material not only has a better capacity retention rate, but also has a higher first-cycle discharge capacity, and the first-cycle discharge capacity is even as high as 308 mAh g -1 .

[0152] According to Comparative Example 1, when the prepared lithium-rich manganese-based material contains less than five metal species other than lithium, has no anion doping, and does not contain a barium sulfate coating layer, the first-cycle discharge capacity is only 237 mAh g -1 , much lower than the embodiment.

[0153] According to Comparative Examples 2-4, it can be seen that when the prepared lithium-rich manganese-based material does not contain a barium sulfate coating layer, or the prepared lithium-rich manganese-based material is neither anion-doped nor contains a barium sulfate coating layer, or the prepared lithium-rich manganese-based material is anion-doped but contains less than five types of metals and has no barium sulfate coating layer, it still has a low first-cycle discharge specific capacity.

[0154] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications are intended to fall within the scope of the present invention.

Claims

1. A double-coated lithium-rich manganese-based material, characterized in that: Its chemical formula is , wherein M includes any three or more of Mg, Al and transition metals, S includes PO4 and / or BO3, A includes one or more of Ca, Sr, Ba and lanthanide metals, and B includes one or more of SO4, PO4, SiO3, SiF6, BF4 and SiO4; 1<x≤1.5, 0.1<y≤0.6, 0.02<z≤0.3, 0<w≤0.5, 1≤a≤3, 1≤b≤4; in the double-coated lithium-rich manganese-based material, A a B b Coated in Li x Mn y Ni z M 2-x-y-z S w O 2-w on the surface; Li in the interior x Mn y Ni z M 2-x-y-z S w O 2-w In the present invention, part of the polyanion S is located inside the crystal lattice of the material, and part of the polyanion S forms a coating layer in the form of metal salt and covers the surface of the material.

2. The double-coated lithium-rich manganese-based material according to claim 1, characterized in that The material meets one or more of the following conditions: (1) In the chemical formula, 1<x≤1.3; (2) In the chemical formula, 0.4<y≤0.6; (3) In the chemical formula, 0.03<z≤0.2; (4) In the chemical formula, 0<w≤0.1; (5) In the chemical formula, A a B b The molar ratio is (0.2-1) mol%; (6) The transition metal includes one or more of Sc, Ti, V, Cr, Fe, Co, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd and Cd; (7) The lanthanide metal includes one or more of La, Ce, Pr, Nd, Pm and Sm.

3. The double-coated lithium-rich manganese-based material according to claim 2, characterized in that In the chemical formula, x is 1.16 or 1.

18.

4. The double-coated lithium-rich manganese-based material according to claim 2, characterized in that In the chemical formula, y is 0.

54.

5. The double-coated lithium-rich manganese-based material according to claim 2, wherein: In the chemical formula, z is 0.06, 0.09 or 0.

11.

6. The double-coated lithium-rich manganese-based material according to claim 2, characterized in that In the chemical formula, w is 0.04, 0.06 or 0.

08.

7. The double-coated lithium-rich manganese-based material according to claim 2, characterized in that In the chemical formula, A a B b The molar ratio is 0.5 mol%, 0.8 mol% or 1 mol%.

8. The double-coated lithium-rich manganese-based material according to claim 1, characterized in that: The M is Mg, Co, Al and Cu; And / or, the S is PO4 and BO3; and / or, said A a B b BaSO4 or Ba3(PO4)2; Or, the chemical formula is: Li 1.18 Mg 0.02 Mr 0.54 Ni 0.11 Co 0.11 Al 0.02 Cu 0.02 (PO4) 0.02 (BO3) 0.02 O 1.96 0.5mol%BaSO4、 Li 1.18 Mg 0.02 Mr 0.54 Ni 0.11 Co 0.09 Al 0.04 Cu 0.02 (PO4) 0.04 (BO3) 0.02 O 1.94 0.5mol%BaSO4、 Li 1.16 Mg 0.04 Mr 0.54 Ni 0.09 Co 0.09 Al 0.04 Cu 0.04 (PO4) 0.02 (BO3) 0.04 O 1.94 1mol%BaSO4、 Li 1.18 Mg 0.02 Mn 0.54 Ni 0.06 Co 0.09 Al 0.04 Cu 0.07 (PO4) 0.04 (BO3) 0.04 The 1.92 1mol%BaSO4、or、 Li 1.18 Mg 0.02 Mr 0.54 Ni 0.06 Co 0.06 Al 0.07 Cu 0.07 (PO4) 0.04 (BO3) 0.04 O 1.92 1mol%BaSO4。 9. A method for preparing a double-coated lithium-rich manganese-based material according to any one of claims 1 to 8, characterized in that: It includes the following steps: (1) A mixed solution containing a lithium source, a sodium source, a manganese source, a nickel source, an M source, a S source, a solvent and a complexing agent is heated to form a gel, and then calcined to obtain a sodium salt precursor; (2) calcining and washing the mixture of the sodium salt precursor, lithium salt, source A and source B to obtain the double-coated lithium-rich manganese-based material.

10. The method for preparing a double-coated lithium-rich manganese-based material according to claim 9, wherein: The preparation method satisfies one or more of the following conditions: (1) The chemical formula of the sodium salt precursor is Na x1 Li x-x1 Mn y Ni z M 2-x-y-z S w O 2-w , where 0.9<x1<1.1; (2) In step (1), the amounts of the lithium source, sodium source, manganese source, nickel source, M source, and S source are added in a stoichiometric ratio according to the chemical formula of the sodium salt precursor; (3) In step (1), the lithium source is a lithium salt soluble in the solvent; (4) In step (1), the sodium source is a sodium salt soluble in the solvent; (5) In step (1), the manganese source is a manganese salt soluble in the solvent; (6) In step (1), the nickel source is a nickel salt soluble in the solvent; (7) In step (1), the M source is one or more of acetate, nitrate and chloride of the corresponding metal; (8) In step (1), the S source is a salt or acid containing the corresponding anion.

11. The method for preparing a double-coated lithium-rich manganese-based material according to claim 10, wherein: The amount of the lithium source used is 1-1.1 times the theoretical amount added.

12. The method for preparing a double-coated lithium-rich manganese-based material according to claim 10, wherein: The lithium source includes one or more of lithium chloride, lithium bromide, lithium iodide, lithium nitrate, lithium acetate, lithium carbonate, lithium phosphate and lithium borate.

13. The method for preparing a double-coated lithium-rich manganese-based material according to claim 10, wherein: The sodium source includes one or more of sodium acetate, sodium nitrate and sodium chloride.

14. The method for preparing a double-coated lithium-rich manganese-based material according to claim 10, wherein: The manganese source includes one or more of manganese acetate, manganese nitrate and manganese chloride.

15. The method for preparing a double-coated lithium-rich manganese-based material according to claim 10, wherein: The nickel source includes one or more of nickel acetate, nickel nitrate and nickel chloride.

16. The method for preparing a double-coated lithium-rich manganese-based material according to claim 10, wherein: The M source is magnesium acetate, cobalt acetate tetrahydrate, aluminum acetate and copper acetate monohydrate.

17. The method for preparing a double-coated lithium-rich manganese-based material according to claim 10, wherein: The S source is one or more of lithium phosphate, lithium borate, ammonium phosphate and boric acid.

18. The method for preparing a double-coated lithium-rich manganese-based material according to claim 17, wherein: The S sources are ammonium phosphate and boric acid.

19. The method for preparing a double-coated lithium-rich manganese-based material according to claim 9, wherein: The preparation method satisfies one or more of the following conditions: (1) In step (1), the solvent is one or more of deionized water, isopropyl alcohol, ethylene glycol, anhydrous ethanol, dimethylformamide and acetone; (2) In step (1), the sum of the mass concentrations of the lithium source, the sodium source, the manganese source, the nickel source, the M source, and the S source is (0.1-0.5) g / mL; (3) In step (1), the complexing agent is one or more of citric acid, maleic acid, glycine, ethyl acetate, ethanolamine and ethylenediaminetetraacetic acid; (4) In step (1), the amount of the complexing agent used is 0.5-2 times the sum of the molar amounts of all metal ions in the manganese source, the nickel source and the M source.

20. The method for preparing a double-coated lithium-rich manganese-based material according to claim 19, wherein: In step (1), the sum of the mass concentrations of the lithium source, the sodium source, the manganese source, the nickel source, the M source, and the S source is (0.2-0.4) g / mL.

21. The method for preparing a double-coated lithium-rich manganese-based material according to claim 19, wherein: In step (1), the amount of the complexing agent used is 1-2 times the sum of the molar amounts of all metal ions in the manganese source, the nickel source and the M source.

22. The method for preparing a double-coated lithium-rich manganese-based material according to claim 9, wherein: The preparation method satisfies one or more of the following conditions: (1) In step (1), the mixed solution is prepared by adding the lithium source, the sodium source, the manganese source, the nickel source, the M source and the S source to the solvent, then adding the complexing agent, and stirring at room temperature until the mixture is completely dissolved; (2) In step (1), the heating temperature is 60-150°C; (3) In step (1), the heating time is 6-24 hours; (4) In step (1), the calcination temperature is 700-1000°C; (5) In step (1), the calcination time is 8-15 hours.

23. The method for preparing a double-coated lithium-rich manganese-based material according to claim 22, wherein: In step (1), the heating temperature is 70-100°C.

24. The method for preparing a double-coated lithium-rich manganese-based material according to claim 22, wherein: In step (1), the heating time is 10-18 hours.

25. The method for preparing a double-coated lithium-rich manganese-based material according to claim 9, wherein: The preparation method satisfies one or more of the following conditions: (1) In step (2), the lithium salt includes one or more of lithium chloride, lithium bromide, lithium iodide, lithium nitrate, lithium acetate, lithium carbonate, lithium phosphate and lithium borate; (2) In step (2), the molar ratio of the sodium salt precursor to the lithium salt is 1:(1.5-3); (3) In step (2), the A source is a salt containing metal A ions; (4) In step (2), the B source is a salt or acid containing the corresponding anion; (5) In step (2), the molar ratio of the A source to the sodium salt precursor is 0.2%-2%; (6) In step (2), the calcination temperature is higher than the melting point of the lithium salt; (7) In step (2), the calcination time is 3-10 hours.

26. The method for preparing a double-coated lithium-rich manganese-based material according to claim 25, wherein: In step (2), the source A is acetate and / or nitrate.

27. The method for preparing a double-coated lithium-rich manganese-based material according to claim 25, wherein: In step (2), the B source is one or more of ammonium phosphate, ammonium sulfate, lithium phosphate, lithium sulfate, lithium silicate, lithium borate, lithium hexafluorosilicate, lithium tetrafluoroborate, lithium metasilicate and boric acid.

28. The method for preparing a double-coated lithium-rich manganese-based material according to claim 25, wherein: The molar ratio of the A source to the sodium salt precursor is 0.2%-1%.

29. The method for preparing a double-coated lithium-rich manganese-based material according to claim 28, wherein: The molar ratio of the A source to the sodium salt precursor is 0.5%, 0.8% or 1%.

30. The method for preparing a double-coated lithium-rich manganese-based material according to claim 25, wherein: In step (2), the calcination temperature is above 10° C. and below 200° C., which is the melting point of the lithium salt.

31. The method for preparing a double-coated lithium-rich manganese-based material according to claim 25, wherein: In step (2), when the lithium salt is lithium chloride, the calcination temperature is 620-800°C.

32. The method for preparing a double-coated lithium-rich manganese-based material according to claim 25, wherein: In step (2), the calcination time is 4-6 hours.

33. Use of the double-coated lithium-rich manganese-based material according to any one of claims 1 to 8 in a lithium-ion battery.

34. A lithium ion battery, characterized in that: It comprises the double-coated lithium-rich manganese-based material according to any one of claims 1 to 8.

Images