Lithium-rich manganese-based precursor, lithium-rich manganese-based positive electrode material, preparation method thereof and battery

Abstract

The invention provides a lithium-rich manganese-based precursor, a lithium-rich manganese-based positive electrode material, a preparation method of the lithium-rich manganese-based precursor, a preparation method of the lithium-rich manganese-based positive electrode material and a battery, the lithium-rich manganese-based precursor is composed of MnaNibM1-a-bO2, a is more than or equal to 0.55 and less than or equal to 0.75, and b is more than or equal to 0.2 and less than or equal to 0.4; m comprises at least three of Zr, Ru, Ga, B, Pb, As, Ba, Ce, La, Bi or Pt; the specific surface area of the lithium-rich manganese-based precursor is not less than 10m < 2 > / g. In the lithium-rich manganese-based precursor, the doping element M improves the component uniformity by adjusting the Zeta potential, forms a eutectic phase at the crystal boundary to inhibit the abnormal growth of crystal grains, enhances the structural uniformity, inhibits the structural collapse of the positive electrode material in circulation, and improves the cycle stability of the battery; meanwhile, pores of the lithium-rich manganese-based precursor provide channels for electrolyte permeation, active sites are increased due to the high specific surface area, lithium ion diffusion is accelerated jointly, and the specific discharge capacity of the positive electrode material is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and relates to a lithium-rich manganese-based precursor, in particular to a lithium-rich manganese-based precursor, a lithium-rich manganese-based positive electrode material, a preparation method thereof and a battery. BACKGROUND

[0002] The lithium-rich manganese-based positive electrode material (molecular general formula: xLi2MnO3·(1-x)LiMO2, wherein M is at least one of Ni, Co and Mn) has become an ideal positive electrode candidate material for the next generation of high-energy-density solid-state batteries due to its ultra-high specific capacity (>250 mAh / g) and high energy density (>900 Wh / kg). However, the material has problems such as structural degradation, voltage attenuation, and interface side reactions in practical application.

[0003] CN119977004A discloses a preparation method of a doped lithium-rich manganese-based precursor material. Fluorine and phosphorus doping elements are synchronously added in the precursor synthesis process and uniformly dispersed in the precursor, so that a precursor morphology with needle-like radial arrangement is synthesized, which is beneficial to the migration and transmission of lithium ions. However, it is still difficult to inhibit oxygen precipitation in the cycle process, and adverse reactions are prone to occur between the positive electrode active material and the solid-state electrolyte.

[0004] CN117441240A discloses a lithium-rich manganese-based positive electrode material, a preparation method and application. In xLi2MnO3·(1-x)LiNi a Co b McO2 material surface, reduces the form of Li2O, thereby reducing lattice oxygen precipitation, further relieving the instability of the Mn element in the surface layer of the material due to oxygen precipitation, reducing the formation of spinel structure with low capacity; the existence of the fast ion conductor layer can also improve the ion diffusion rate between the lithium-rich manganese-based positive electrode materials, thereby effectively improving the ion conductivity of the lithium-rich manganese-based positive electrode material, improving the capacity, and improving the rate capability and cycle performance.

[0005] The lithium-rich manganese-based precursors disclosed in the prior art have certain defects, and have problems of unstable structure and low specific surface area, thereby causing problems of serious voltage attenuation, poor cycle stability and low discharge specific capacity of the battery containing the lithium-rich manganese-based positive electrode material prepared from the lithium-rich manganese-based precursor. Therefore, it is crucial to develop and design a new lithium-rich manganese-based precursor, a lithium-rich manganese-based positive electrode material, a preparation method thereof and a battery. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a lithium-rich manganese-based precursor, a lithium-rich manganese-based positive electrode material and a battery, wherein the lithium-rich manganese-based precursor, the doping element M improves the composition uniformity by adjusting the Zeta potential, forms a eutectic phase at the grain boundary to inhibit abnormal grain growth and enhance the structural uniformity, thereby inhibiting the structure collapse of the positive electrode material in the cycle and improving the cycle stability of the battery; at the same time, the pores of the lithium-rich manganese-based precursor provide channels for electrolyte penetration, the high specific surface area increases the active sites, and together accelerates the lithium ion diffusion, thereby improving the discharge specific capacity of the positive electrode material.

[0007] To achieve this purpose, the present application adopts the following technical solutions:

[0008] In a first aspect, the present application provides a lithium-rich manganese-based precursor, wherein the lithium-rich manganese-based precursor has a composition of Mn a Ni b M 1-a-b O2, wherein 0.55≤a≤0.75, 0.2≤b≤0.4; wherein M includes a combination of at least three of Zr, Ru, Ga, B, Pb, As, Ba, Ce, La, Bi or Pt.

[0009] The specific surface area of the lithium-rich manganese-based precursor is not less than 10 m 2 / g.

[0010] In the present application, the specific surface area of the lithium-rich manganese-based precursor is not less than 10 m 2 / g, for example, it can be 10 m 2 / g, 12 m 2 / g, 15 m 2 / g, 18 m 2 / g, 20 m 2 / g, 25 m 2 / g, 30 m 2 / g, 35 m 2 / g, 40 m 2 / g, 45 m 2 / g or 50 m 2 / g, but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0011] In the lithium-rich manganese-based precursor provided by the present application, the doping element M is introduced, the doping element M includes a combination of at least three of Zr, Ru, Ga, B, Pb, As, Ba, Ce, La, Bi or Pt, the doping of the doping element M shortens the Mn-O bond length and improves the structural stability of the lithium-rich manganese-based precursor.

[0012] In the lithium-rich manganese-based precursor provided by this invention, the introduction of dopant element M significantly improves the compositional and dimensional uniformity of the precursor. Dopant element M promotes more uniform dispersion of manganese, nickel, and doped metal ions in the liquid phase by adjusting the zeta potential of the raw material system, thereby improving the compositional uniformity of the lithium-rich manganese-based precursor. In addition, the segregation of dopant element M at the grain boundaries forms a eutectic phase, which effectively suppresses abnormal grain growth and makes the grain size of the lithium-rich manganese-based precursor more uniform. Therefore, the lithium-rich manganese-based precursor with higher compositional and dimensional uniformity suppresses stress concentration caused by compositional segregation and grain size inhomogeneity, enhances the structural uniformity of the lithium-rich manganese-based precursor, thereby suppressing the structural collapse of the lithium-rich manganese-based cathode material during cycling and improving the cycle stability of the battery.

[0013] The lithium-rich manganese-based precursor provided by this invention has pores and a high specific surface area, thereby improving the diffusion rate of lithium ions in the lithium-rich manganese-based cathode material prepared from the lithium-rich manganese-based precursor. The pores of the lithium-rich manganese-based cathode material provide channels for electrolyte penetration, increasing the contact area between the electrode and the electrolyte. The high specific surface area increases the number of active reaction sites, which helps to accelerate the insertion and extraction of lithium ions, thereby improving the discharge specific capacity of the lithium-rich manganese-based cathode material.

[0014] Preferably, 0.005 ≤ 1-ab ≤ 0.05, where the value of 1-ab can be, for example, 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045 or 0.05, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0015] Preferably, M includes Ce, La, and Bi.

[0016] In this invention, M includes Ce, La, and Bi. The doping of these three elements synergistically achieves redox buffering, lattice anchoring, and surface energy modulation of the lithium-rich manganese-based precursor. Redox buffer: Ce 4+ With Ce 3+ Reversible energy change regulates local charge balance and inhibits metal particle aggregation; lattice anchoring: La 3+ (ionic radius) It can pin grain boundaries, hindering grain migration; surface energy modulation: Bi 3+ with Bi 5+ The 6p lone pair induces surface reconstruction, forming a bond length gradient with the support (such as the Bi-O bond length). This improves the uniformity of metal precursors.

[0017] Preferably, the molar ratio of Ce, La and Bi in M ​​is (0.5-1.5):(0.5-1.5):1.

[0018] In the present application, the molar ratio of Ce to Bi in M is (0.5-1.5):1, for example, it can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1 or 1.5:1, but not limited to the listed values, other values not listed in the range are also applicable.

[0019] In the present application, the molar ratio of La to Bi in M is (0.5-1.5):1, for example, it can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1 or 1.5:1, but not limited to the listed values, other values not listed in the range are also applicable.

[0020] In a second aspect, the present application provides a preparation method of the lithium-rich manganese-based precursor of the first aspect, the preparation method comprising:

[0021] mixing the manganese salt, the nickel salt, the doped metal M salt, the additive and the solvent to obtain a mixed solution; and performing spray pyrolysis on the obtained mixed solution as raw material to obtain the lithium-rich manganese-based precursor;

[0022] The doped metal M salt comprises a combination of at least three of Zr salt, Ru salt, Ga salt, B salt, Pb salt, As salt, Ba salt, Ce salt, La salt, Bi salt or Pt salt.

[0023] In the preparation method provided by the present application, the obtained mixed solution is used as raw material for spray pyrolysis, and the lithium-rich manganese-based precursor prepared by spray pyrolysis has high dispersity. The improvement of dispersity reduces particle agglomeration, reduces internal stress and enhances structural stability. In addition, the improvement of dispersity also reduces particle wrapping, exposes more surface and increases the specific surface area of the prepared lithium-rich manganese-based precursor.

[0024] In the preparation method provided by the present application, the obtained mixed solution is used as raw material for spray pyrolysis, and the lithium-rich manganese-based precursor prepared by spray pyrolysis has high dispersity. The improvement of dispersity reduces particle agglomeration, reduces internal stress and enhances structural stability. In addition, the improvement of dispersity also reduces particle wrapping, exposes more surface and increases the specific surface area of the prepared lithium-rich manganese-based precursor.

[0025] Preferably, the manganese salt, the nickel salt and the doping metal M salt each independently comprises any one or a combination of at least two of a sulfate salt, a carbonate salt, a chloride salt or a nitrate salt, typically but not limitedly a combination of a sulfate salt and a carbonate salt, a combination of a chloride salt and a nitrate salt, a combination of a sulfate salt and a chloride salt, a combination of a carbonate salt and a nitrate salt, or a combination of a sulfate salt, a chloride salt and a nitrate salt.

[0026] Preferably, the mixing further comprises mixing in an additive.

[0027] Preferably, the additive comprises a first additive and a second additive; the first additive comprises any one or a combination of at least two of sodium dodecyl sulfate, polysorbate-80 or alkyl glycoside, typically but not limitedly a combination of sodium dodecyl sulfate and polysorbate-80, polysorbate-80 and alkyl glycoside, sodium dodecyl sulfate and alkyl glycoside, or sodium dodecyl sulfate, polysorbate-80 and alkyl glycoside; the second additive comprises ammonium chloride.

[0028] In the present application, by adding ammonium chloride in the mixing, since ammonium chloride has a lower boiling point, it is easy to volatilize in the spray pyrolysis, thereby forming pores in the lithium-rich manganese-based precursor, obtaining a lithium-rich manganese-based precursor with pores.

[0029] Preferably, the solvent comprises any one or a combination of at least two of water, ethanol, methanol or ethyl acetate, typically but not limitedly a combination of water and ethanol, methanol and ethyl acetate, water and methanol, ethanol and ethyl acetate, or water, ethanol and methanol.

[0030] Preferably, the molar ratio of the manganese salt, the nickel salt and the doping metal M salt in the mixed solution is (55-75):(20-40):(0.5-5).

[0031] In the present application, the molar ratio of the manganese salt and the nickel salt in the mixed solution is (55-75):(20-40), for example, it can be 55:20, 58:25, 60:30, 62:35, 65:35, 68:30, 70:25, 72:20 or 75:40, but is not limited to the listed values, other values not listed in this range are also applicable.

[0032] In the present application, the molar ratio of the manganese salt and the doping metal M salt in the mixed solution is (55-75):(0.5-5), for example, it can be 55:0.5, 58:1, 60:1.5, 62:2, 65:2.5, 68:3, 70:3.5, 72:4 or 75:5, but is not limited to the listed values, other values not listed in this range are also applicable.

[0033] Preferably, the mass concentration of total metal ions in the mixed solution is 50g / L-250g / L, for example, it can be 50g / L, 75g / L, 100g / L, 125g / L, 150g / L, 175g / L, 200g / L, 225g / L or 250g / L, but not only limited to the listed values, other values not listed in the range are also applicable.

[0034] Preferably, the mass fraction of the first additive in the mixed solution is 0.1wt%-5wt% based on 100% of the mass of the mixed solution, for example, it can be 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt% or 5wt%, but not only limited to the listed values, other values not listed in the range are also applicable.

[0035] Preferably, the mass fraction of the second additive in the mixed solution is 10wt%-20wt% based on 100% of the mass of the mixed solution, for example, it can be 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt% or 20wt%, but not only limited to the listed values, other values not listed in the range are also applicable.

[0036] Preferably, the spray pyrolysis comprises: turning on the power supply of the spray pyrolysis device, adjusting the frequency control negative pressure of the fan, opening the circulating pump, preheating the pyrolysis furnace temperature to the required temperature, then opening the metering pump feeding, adjusting the flow rate and compressed air pressure of the feed liquid, until the ideal atomization effect is adjusted, then starting normal feeding, and the mist droplets enter the pyrolysis furnace under the blowing of compressed air for sufficient pyrolysis to obtain a lithium-rich manganese-based precursor.

[0037] Preferably, the spray pyrolysis is divided into two stages; the temperature of the first stage pyrolysis in the spray pyrolysis is 200℃-500℃, and the temperature of the second stage pyrolysis is 600℃-1000℃.

[0038] In the present application, the temperature of the first stage pyrolysis in the spray pyrolysis is 200℃-500℃, for example, it can be 200℃, 250℃, 300℃, 350℃, 400℃, 450℃ or 500℃, but not only limited to the listed values, other values not listed in the range are also applicable.

[0039] In the present application, the temperature of the second pyrolysis in the spray pyrolysis is 600-1000℃, for example, it can be 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃ or 1000℃, but not limited to the listed values, other values not listed in the range are also applicable.

[0040] Preferably, the frequency of the fan during the spray pyrolysis is 0-50Hz, for example, it can be 0Hz, 5Hz, 10Hz, 15Hz, 20Hz, 25Hz, 30Hz, 35Hz, 40Hz, 45Hz or 50Hz, but not limited to the listed values, other values not listed in the range are also applicable.

[0041] Preferably, the feed flow rate during the spray pyrolysis is 2-15L / h, for example, it can be 2L / h, 3L / h, 4L / h, 5L / h, 6L / h, 7L / h, 8L / h, 9L / h, 10L / h, 11L / h, 12L / h, 13L / h, 14L / h or 15L / h, but not limited to the listed values, other values not listed in the range are also applicable.

[0042] Preferably, the compressed air pressure during the spray pyrolysis is 0.1-0.8MPa, for example, it can be 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa or 0.8MPa, but not limited to the listed values, other values not listed in the range are also applicable.

[0043] Preferably, the preparation method further comprises post-processing after the spray pyrolysis, the post-processing comprising: after natural cooling to room temperature, taking out the material after spray pyrolysis, washing 1-3 times with hot water, drying in an oven at 120-180℃ for 15-30h, and then sequentially performing screening and iron removal.

[0044] In the present application, the drying in the oven is at 120-180℃, for example, it can be 120℃, 130℃, 140℃, 150℃, 160℃, 170℃ or 180℃, but not limited to the listed values, other values not listed in the range are also applicable.

[0045] In the present application, the drying in the oven is for 15-30h, for example, it can be 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, 29h or 30h, but not limited to the listed values, other values not listed in the range are also applicable.

[0046] In a third aspect, the present application provides a lithium-rich manganese-based positive electrode material, which is prepared from raw materials comprising the lithium-rich manganese-based precursor of the first aspect.

[0047] Preferably, the lithium-rich manganese-based positive electrode material comprises a positive electrode material core, and a lithium phosphate layer coated on the outside of the positive electrode material core.

[0048] In the lithium-rich manganese-based positive electrode material provided by the present application, a lithium phosphate layer is formed on the surface of the positive electrode material core, which improves the interface compatibility of the lithium-rich manganese-based positive electrode material, and avoids poor contact between the positive electrode material core and the solid-state electrolyte, thereby hindering the formation of a high-resistance interface layer and facilitating the migration and transport of lithium ions.

[0049] Preferably, the D50 particle size of the positive electrode material core is 100 nm to 1000 nm, for example, it can be 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm or 1000 nm, but is not limited to the listed values, and other values not listed within this range are also applicable.

[0050] Preferably, the thickness of the lithium phosphate layer is 1 nm to 10 nm, for example, it can be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm, but is not limited to the listed values, and other values not listed within this range are also applicable.

[0051] In a fourth aspect, the present application provides a preparation process of the lithium-rich manganese-based positive electrode material of the third aspect, which comprises:

[0052] The lithium-rich manganese-based precursor of the first aspect is mixed with a lithium source, and then solid-phase sintering is performed to obtain a positive electrode material core, and then a lithium phosphate layer is coated on the outside of the obtained positive electrode material core through atomic layer deposition to obtain a lithium-rich manganese-based positive electrode material.

[0053] In the preparation process provided by the present application, by controlling the cycle conditions in each cycle of atomic layer deposition, including the type of lithium source, the time of pulse for the lithium source, the type of phosphorus source, the time of pulse for the phosphorus source, and the number of cycles, the thickness and uniformity of the lithium phosphate layer can be precisely controlled.

[0054] Preferably, the lithium source comprises any one or a combination of at least two of lithium hydroxide, lithium carbonate, lithium chloride, lithium sulfate or lithium nitrate, and typical but non-limiting combinations include a combination of lithium hydroxide and lithium carbonate, a combination of lithium chloride and lithium sulfate, a combination of lithium carbonate and lithium nitrate, or a combination of lithium hydroxide, lithium carbonate and lithium chloride.

[0055] Preferably, the molar ratio of total metal elements in the lithium-rich manganese-based precursor to lithium elements in the lithium source in the mixing is 1:(1.0-1.5), for example, it can be 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0056] Preferably, the temperature of the solid-phase sintering is 550-950°C, and the time is 2-24h.

[0057] In the present application, the temperature of the solid-phase sintering is 550-950°C, for example, it can be 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C or 950°C, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0058] In the present application, the time of the solid-phase sintering is 2-24h, for example, it can be 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or 24h, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0059] Preferably, the mixing further comprises a temperature rising treatment before the solid-phase sintering, the temperature rising treatment comprises rising the temperature of the mixture obtained after the mixing, and the rising rate is 3-10°C / min, for example, it can be 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0060] Preferably, the ambient atmosphere during the solid-phase sintering comprises at least one of nitrogen atmosphere, oxygen atmosphere, air atmosphere or argon atmosphere, and typical but non-limiting combinations include a mixed atmosphere of nitrogen and oxygen, a mixed atmosphere of air and argon, a mixed atmosphere of nitrogen, oxygen and argon, or a single nitrogen atmosphere, a single oxygen atmosphere, a single air atmosphere, a single argon atmosphere.

[0061] Preferably, the solid-phase sintering and the atomic layer deposition further comprise a pretreatment of the obtained positive electrode material core; the pretreatment comprises vacuum drying the obtained positive electrode material core at 100-140°C for 10-14h to remove surface adsorbed water.

[0062] In the present application, the obtained positive electrode material core is vacuum dried at 100℃ to 140℃, for example, it can be 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃ or 140℃, but not limited to the listed values, other values not listed in the range are also applicable.

[0063] In the present application, the obtained positive electrode material core is vacuum dried for 10h to 14h, for example, it can be 10h, 10.5h, 11h, 11.5h, 12h, 12.5h, 13h, 13.5h or 14h, but not limited to the listed values, other values not listed in the range are also applicable.

[0064] Preferably, at least one cycle is performed in the atomic layer deposition, and each cycle comprises: sequentially performing a lithium source pulse, a nitrogen gas purge, a phosphorus source pulse and a secondary purge.

[0065] Preferably, in the atomic layer deposition, the temperature of the reaction is set to 100℃ to 500℃, and the number of cycles is 10 to 100.

[0066] In the present application, the temperature of the reaction in the atomic layer deposition is set to 100℃ to 500℃, for example, it can be 100℃, 150℃, 200℃, 250℃, 300℃, 350℃, 400℃, 450℃ or 500℃, but not limited to the listed values, other values not listed in the range are also applicable.

[0067] In the present application, the number of cycles of the reaction in the atomic layer deposition is set to 10 to 100, for example, it can be 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100, but not limited to the listed values, other values not listed in the range are also applicable.

[0068] Preferably, the carrier gas in the atomic layer deposition includes at least one of nitrogen, oxygen, air, hydrogen or argon, and typical but non-limiting combinations include combinations of nitrogen and oxygen, air and argon, hydrogen and nitrogen, oxygen and argon, or nitrogen, oxygen and argon.

[0069] Preferably, the deposition lithium source delivered in the atomic layer deposition includes any one or a combination of at least two of tert-butyllithium, n-butyllithium, iso-butyllithium or methyl lithium, and typical but non-limiting combinations include combinations of tert-butyllithium and n-butyllithium, iso-butyllithium and methyl lithium, n-butyllithium and methyl lithium, or tert-butyllithium, iso-butyllithium and methyl lithium.

[0070] Preferably, in the atomic layer deposition, the temperature of the delivered deposition lithium source is 100-200°C, and the time for pulsing the deposition lithium source is 500-2000 ms.

[0071] In the present application, in the atomic layer deposition, the temperature of the delivered deposition lithium source is 100-200°C, for example, it can be 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C or 200°C, but not limited to the listed values, other values not listed in this range are also applicable.

[0072] In the present application, in the atomic layer deposition, the time for pulsing the deposition lithium source is 500-2000 ms, for example, it can be 500 ms, 600 ms, 700 ms, 800 ms, 900 ms, 1000 ms, 1100 ms, 1200 ms, 1300 ms, 1400 ms, 1500 ms, 1600 ms, 1700 ms, 1800 ms, 1900 ms or 2000 ms, but not limited to the listed values, other values not listed in this range are also applicable.

[0073] Preferably, in the atomic layer deposition, the deposition phosphorus source used includes any one of trimethyl phosphate, triethyl phosphate, trimethyl phosphorus or triisopropyl phosphate or a combination of at least two, and a typical but non-limiting combination includes a combination of trimethyl phosphate and triethyl phosphate, a combination of trimethyl phosphorus and triisopropyl phosphate, a combination of trimethyl phosphate and trimethyl phosphorus, or a combination of trimethyl phosphate, triethyl phosphate and trimethyl phosphorus.

[0074] Preferably, in the atomic layer deposition, the temperature of the delivered deposition phosphorus source is 30-80°C, and the time for pulsing the deposition phosphorus source is 50-500 ms.

[0075] In the present application, in the atomic layer deposition, the temperature of the delivered deposition phosphorus source is 30-80°C, for example, it can be 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, but not limited to the listed values, other values not listed in this range are also applicable.

[0076] In the present application, in the atomic layer deposition, the time for pulsing the deposition phosphorus source is 50-500 ms, for example, it can be 50 ms, 100 ms, 150 ms, 200 ms, 250 ms, 300 ms, 350 ms, 400 ms, 450 ms or 500 ms, but not limited to the listed values, other values not listed in this range are also applicable.

[0077] Preferably, the atomic layer deposition is followed by annealing, which is performed in a protective atmosphere at a temperature of 250-350 DEG C for a time period of 0.5-1.5 h.

[0078] In the present application, the annealing is performed in a protective atmosphere at a temperature of 250-350 DEG C, for example, it can be 250 DEG C, 260 DEG C, 270 DEG C, 280 DEG C, 290 DEG C, 300 DEG C, 310 DEG C, 320 DEG C, 330 DEG C, 340 DEG C or 350 DEG C, but not limited to the listed values, other values not listed in the range are also applicable.

[0079] In the present application, the annealing is performed in a protective atmosphere for a time period of 0.5-1.5 h, for example, it can be 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1.0 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h or 1.5 h, but not limited to the listed values, other values not listed in the range are also applicable.

[0080] In a fifth aspect, the present application provides a battery comprising the lithium-rich manganese-based positive electrode material of the third aspect.

[0081] The numerical ranges of the present application include not only the above-mentioned point values, but also any point values between the above-mentioned numerical ranges, which are not listed due to the limited space and for the sake of simplicity.

[0082] Compared with the prior art, the present application has the following beneficial effects:

[0083] (1) In the lithium-rich manganese-based precursor provided by the present application, a doping element M is introduced, the doping element M includes a combination of at least three of Zr, Ru, Ga, B, Pb, As, Ba, Ce, La, Bi or Pt, the doping of the doping element M shortens the Mn-O bond length and improves the structural stability of the lithium-rich manganese-based precursor.

[0084] (2) The lithium-rich manganese-based precursor provided by the present application has the advantages that: the introduction of the doping element M significantly improves the composition uniformity and size uniformity of the lithium-rich manganese-based precursor; the doping element M promotes the more uniform dispersion of manganese, nickel and doping metal ions in the liquid phase by adjusting the Zeta potential of the raw material system, thereby improving the composition uniformity of the lithium-rich manganese-based precursor; in addition, the doping element M is aggregated at the grain boundaries to form a eutectic phase, which effectively inhibits the abnormal growth of the crystal grains, so that the lithium-rich manganese-based precursor has more uniform grain size. Therefore, the lithium-rich manganese-based precursor with higher composition uniformity and size uniformity inhibits stress concentration caused by composition segregation and non-uniform grain size, enhances the structural uniformity of the lithium-rich manganese-based precursor, thereby inhibiting the structural collapse of the lithium-rich manganese-based positive electrode material in the cycle process, and improving the cycle stability of the battery.

[0085] (3) The lithium-rich manganese-based precursor provided by the present application has pores and a high specific surface area, thereby improving the lithium ion diffusion rate of the lithium-rich manganese-based positive electrode material prepared from the lithium-rich manganese-based precursor; the high porosity provides sufficient channels for electrolyte penetration, increases the contact area of the electrode and the electrolyte; and the high specific surface area increases the active reaction sites, which helps to speed up the lithium ion insertion and extraction process, thereby improving the discharge specific capacity of the lithium-rich manganese-based positive electrode material. DETAILED DESCRIPTION

[0086] The technical solutions of the present application will be further described through specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations on the present application.

[0087] Embodiment 1

[0088] The present embodiment provides a lithium-rich manganese-based precursor, wherein the composition of the lithium-rich manganese-based precursor is Mn a Ni b M 1-a- b O2, wherein a=0.6, b=0.38, and 1-a-b=0.02; wherein M includes Ce, La and Bi in a molar ratio of 1:1:1; the surface area of the lithium-rich manganese-based precursor is 13 m 2 / g.

[0089] The preparation method of the lithium-rich manganese-based precursor is as follows:

[0090] (1) mixing manganese chloride, nickel chloride, a doping metal M salt (including cerium chloride, lanthanum chloride and bismuth chloride in a molar ratio of 1:1:1), sodium dodecyl sulfate, ammonium chloride and water to obtain a mixed solution;

[0091] The molar ratio of manganese chloride, nickel chloride and metal M doping salt in the mixed solution is 0.6:0.38:0.02, and the mass concentration of total metal ions is 150 g / L; the mass fraction of sodium dodecyl sulfate in the mixed solution is 2 wt%, and the mass fraction of ammonium chloride is 15 wt% based on 100% of the mass of the mixed solution;

[0092] (2) The obtained mixed solution is used as raw material for spray pyrolysis, and the spray pyrolysis is divided into two stages; the temperature of the first stage pyrolysis is 550℃, and the temperature of the second stage pyrolysis is 800℃; the frequency of the fan is 20 Hz, the feeding flow rate is 8 L / h, and the compressed air pressure is 0.4 MPa during the spray pyrolysis;

[0093] After the spray pyrolysis, the material is naturally cooled to 25℃, then taken out, washed with hot water for 3 times, dried in an oven at 150℃ for 24 h, and then screened and de-ironed in sequence to obtain the lithium-rich manganese-based precursor.

[0094] The embodiment also provides a lithium-rich manganese-based positive electrode material, which is prepared from the raw material of the lithium-rich manganese-based precursor described above, and includes a positive electrode material core with a D50 particle size of 500 nm, and a lithium phosphate layer with a thickness of 5 nm coated outside the positive electrode material core.

[0095] The preparation process of the lithium-rich manganese-based precursor is as follows:

[0096] (I) After mixing the lithium-rich manganese-based precursor described above and lithium carbonate in a molar ratio of 1:1.3, solid-phase sintering is performed in an air atmosphere at a temperature of 750℃ for 12 h with a temperature rising rate of 5℃ / min to obtain a positive electrode material core;

[0097] (II) After vacuum drying the positive electrode material core obtained in step (I) at 120℃ for 12 h to remove the surface adsorbed water, a lithium phosphate layer is coated outside the positive electrode material core through atomic layer deposition, and then annealing is performed in an argon atmosphere at a temperature of 300℃ for 1 h to obtain a lithium-rich manganese-based positive electrode material;

[0098] In the atomic layer deposition, 50 cycles are performed, and each cycle includes: sequentially performing a lithium source pulse, nitrogen blowing, a phosphorus source pulse and twice blowing;

[0099] In the atomic layer deposition, the reaction temperature is set to 250℃, and the carrier gas is nitrogen;

[0100] In the atomic layer deposition, the deposited lithium source is tert-butyl lithium, the temperature of the deposited lithium source is 120℃, and the pulse time of the deposited lithium source is 1000 ms;

[0101] The phosphorus source used in the atomic layer deposition is trimethyl phosphate, the temperature of the delivered phosphorus source is 45℃, and the time for pulsing the phosphorus source is 275ms.

[0102] Embodiment 2

[0103] The embodiment provides a lithium-rich manganese-based precursor, the lithium-rich manganese-based precursor has a composition of Mn a Ni b M 1-a- b O2, wherein a = 0.55, b = 0.4, and 1-a-b = 0.05; wherein M includes Ce, La, and Bi in a molar ratio of 0.5:1.5:1; the lithium-rich manganese-based precursor has a specific surface area of 25m 2 / g.

[0104] The preparation method of the lithium-rich manganese-based precursor is as follows:

[0105] (1) mixing manganese sulfate, nickel sulfate, doped metal M salt (including cerium sulfate, lanthanum sulfate, and bismuth sulfate in a molar ratio of 0.5:1.5:1), polysorbate-80, ammonium chloride, and water to obtain a mixed solution;

[0106] The molar ratio of manganese sulfate, nickel sulfate, and doped metal M salt in the mixed solution is 55:40:5, and the mass concentration of total metal ions is 250g / L; the mass fraction of polysorbate-80 in the mixed solution is 5wt%, and the mass fraction of ammonium chloride is 10wt% based on 100% of the mass of the mixed solution;

[0107] (2) spray pyrolysis is performed using the obtained mixed solution as raw material, and the spray pyrolysis is divided into two stages; the temperature of the first-stage pyrolysis is 200℃, and the temperature of the second-stage pyrolysis is 1000℃; the frequency of the fan is 50Hz, the feeding flow rate is 2L / h, and the compressed air pressure is 0.1MPa during the spray pyrolysis;

[0108] After the spray pyrolysis, natural cooling is performed to room temperature, then the material after the spray pyrolysis is taken out, washed once with hot water, dried in an oven at 180℃ for 15h, and then sequentially subjected to screening and iron removal to obtain the lithium-rich manganese-based precursor.

[0109] The embodiment also provides a lithium-rich manganese-based positive electrode material, which is prepared from the raw material of the lithium-rich manganese-based precursor described above, and includes a positive electrode material core with a D50 particle size of 100nm, and a lithium phosphate layer with a thickness of 1nm coated outside the positive electrode material core.

[0110] The preparation process of the lithium-rich manganese-based precursor is as follows:

[0111] (I) mixing the above lithium-rich manganese-based precursor and lithium hydroxide in a molar ratio of 1:1.5, then performing solid-phase sintering at a temperature of 550℃ for 24h under a nitrogen atmosphere at a temperature increasing rate of 3℃ / min to obtain a positive electrode material core;

[0112] (II) vacuum drying the positive electrode material core obtained in step (I) at 140℃ for 10h to remove surface adsorbed water, then coating a lithium phosphate layer on the outside of the positive electrode material core through atomic layer deposition, and then performing annealing at a temperature of 250℃ for 1.5h under a nitrogen atmosphere to obtain a lithium-rich manganese-based positive electrode material;

[0113] The atomic layer deposition is performed for 20 cycles, and each cycle includes sequentially performing a lithium source pulse, nitrogen blowing, a phosphorus source pulse, and double blowing;

[0114] In the atomic layer deposition, the reaction temperature is set to 100℃, and the carrier gas is nitrogen;

[0115] In the atomic layer deposition, the deposited lithium source delivered includes n-butyllithium, the temperature of the deposited lithium source delivered is 100℃, and the time for pulsing the deposited lithium source is 500ms;

[0116] In the atomic layer deposition, the deposited phosphorus source used includes triethyl phosphate, the temperature of the deposited phosphorus source delivered is 30℃, and the time for pulsing the deposited phosphorus source is 50ms.

[0117] Example 3

[0118] This example provides a lithium-rich manganese-based precursor, the composition of the lithium-rich manganese-based precursor being Mn a Ni b M 1-a- b O2, wherein a=0.75, b=0.245, 1-a-b=0.005; wherein M includes Ce, La, and Bi in a molar ratio of 1.5:0.5:1; the specific surface area of the lithium-rich manganese-based precursor is 10m 2 / g.

[0119] The preparation method of the lithium-rich manganese-based precursor is as follows:

[0120] (1) mixing manganese nitrate, nickel nitrate, doped metal M salt (including cerium nitrate, lanthanum nitrate, and bismuth nitrate in a molar ratio of 1.5:0.5:1), alkyl glycoside, ammonium chloride, and ethyl acetate to obtain a mixed solution;

[0121] The molar ratio of manganese nitrate, nickel nitrate and metal M salt in the mixed solution is 75:24.5:0.5, and the mass concentration of total metal ions is 50 g / L; the mass fraction of alkyl polyglycoside in the mixed solution is 0.1 wt%, and the mass fraction of ammonium chloride is 20 wt% based on 100% of the mass of the mixed solution;

[0122] (2) The obtained mixed solution is used as raw material for spray pyrolysis, and the spray pyrolysis is divided into two stages; the temperature of the first stage pyrolysis is 500℃, and the temperature of the second stage pyrolysis is 600℃; the frequency of the fan is 5 Hz, the feeding flow rate is 15 L / h, and the compressed air pressure is 0.8 MPa during the spray pyrolysis;

[0123] After the spray pyrolysis, the material is naturally cooled to room temperature, then taken out, washed with hot water for 2 times, dried in an oven at 120℃ for 30 h, and then screened and de-ironed in sequence to obtain the lithium-rich manganese-based precursor.

[0124] The embodiment also provides a lithium-rich manganese-based positive electrode material, which is prepared from the raw material of the lithium-rich manganese-based precursor described above, and includes a positive electrode material core with a D50 particle size of 1000 nm, and a lithium phosphate layer with a thickness of 10 nm coated outside the positive electrode material core.

[0125] The preparation process of the lithium-rich manganese-based precursor is as follows:

[0126] (I) After mixing the lithium-rich manganese-based precursor described above and lithium carbonate in a molar ratio of 1:1.0, solid-phase sintering is performed at a temperature of 950℃ for 2 h under a nitrogen atmosphere at a temperature increasing rate of 10℃ / min to obtain a positive electrode material core;

[0127] (II) After vacuum drying the positive electrode material core obtained in step (I) at 100℃ for 14 h to remove the surface adsorbed water, a lithium phosphate layer is coated outside the positive electrode material core through atomic layer deposition, and then annealing is performed at a temperature of 350℃ for 0.5 h under an argon atmosphere to obtain a lithium-rich manganese-based positive electrode material;

[0128] In the atomic layer deposition, 100 cycles are performed, and each cycle includes: sequentially performing a lithium source pulse, nitrogen blowing, a phosphorus source pulse and twice blowing;

[0129] In the atomic layer deposition, the reaction temperature is set to 500℃, the cycle number is 100, and the carrier gas is nitrogen;

[0130] In the atomic layer deposition, the deposited lithium source delivered includes isobutyl lithium, the temperature of the deposited lithium source delivered is 200℃, and the time for pulsing the deposited lithium source is 2000 ms;

[0131] The phosphorus source for deposition used in the atomic layer deposition includes triisopropyl phosphate, the temperature of the delivered phosphorus source is 80℃, and the time for pulsing the phosphorus source is 500ms.

[0132] Embodiment 4

[0133] The lithium-rich manganese-based precursor provided in the embodiment includes M including Zr, Ga and Ru in a molar ratio of 1:1:1.1.

[0134] The step (1) of the preparation method of the lithium-rich manganese-based precursor is replaced by doping metal M salt in an equivalent molar amount (including zirconium chloride, gallium chloride and ruthenium chloride in a molar ratio of 1:1:1.1), and the rest is the same as Embodiment 1.

[0135] The lithium-rich manganese-based anode material provided in the embodiment is prepared by replacing the lithium-rich manganese-based precursor in step (I) of the preparation process of the lithium-rich manganese-based precursor with the lithium-rich manganese-based precursor in the embodiment, and the rest is the same as Embodiment 1.

[0136] Embodiment 5

[0137] The lithium-rich manganese-based precursor provided in the embodiment includes M including Pb, As and Ba in a molar ratio of 1:1:1.1.

[0138] The step (1) of the preparation method of the lithium-rich manganese-based precursor is replaced by doping metal M salt in an equivalent molar amount (including lead chloride, arsenic chloride and barium chloride in a molar ratio of 1:1:1.1), and the rest is the same as Embodiment 1.

[0139] The lithium-rich manganese-based anode material provided in the embodiment is prepared by replacing the lithium-rich manganese-based precursor in step (I) of the preparation process of the lithium-rich manganese-based precursor with the lithium-rich manganese-based precursor in the embodiment, and the rest is the same as Embodiment 1.

[0140] Embodiment 6

[0141] The lithium-rich manganese-based precursor provided in the embodiment includes a=0.6, b=0.399, and 1-a-b=0.001.

[0142] The step (1) of the preparation method of the lithium-rich manganese-based precursor is replaced by doping metal M salt in an equivalent molar amount (including lead chloride, arsenic chloride and barium chloride in a molar ratio of 1:1:1.1), and the rest is the same as Embodiment 1.

[0143] The lithium-rich manganese-based anode material provided in the embodiment is prepared by replacing the lithium-rich manganese-based precursor in step (I) of the preparation process of the lithium-rich manganese-based precursor with the lithium-rich manganese-based precursor in the embodiment, and the rest is the same as Embodiment 1.

[0144] Example 7

[0145] The embodiment provides a lithium-rich manganese-based precursor, wherein a=0.6, b=0.3, and 1-a-b=0.1.

[0146] In step (1) of the preparation method of the lithium-rich manganese-based precursor, the molar ratio of manganese chloride, nickel chloride and the salt of the doping metal M in the mixed solution is 0.6:0.3:0.1, and the rest is the same as in example 1.

[0147] The embodiment further provides a lithium-rich manganese-based positive electrode material, wherein the lithium-rich manganese-based precursor in step (I) in the preparation process of the lithium-rich manganese-based precursor is replaced by the lithium-rich manganese-based precursor in the embodiment, and the rest is the same as in example 1.

[0148] Example 8

[0149] The embodiment provides a lithium-rich manganese-based precursor, wherein M includes Ce, La and Bi in a molar ratio of 0.2:1:1.

[0150] In step (1) of the preparation method of the lithium-rich manganese-based precursor, the molar ratio of cerium chloride, lanthanum chloride and bismuth chloride in the salt of the doping metal M in the mixed solution is 0.2:1:1, and the rest is the same as in example 1.

[0151] The embodiment further provides a lithium-rich manganese-based positive electrode material, wherein the lithium-rich manganese-based precursor in step (I) in the preparation process of the lithium-rich manganese-based precursor is replaced by the lithium-rich manganese-based precursor in the embodiment, and the rest is the same as in example 1.

[0152] Example 9

[0153] The embodiment provides a lithium-rich manganese-based precursor, wherein M includes Ce, La and Bi in a molar ratio of 2:1:1.

[0154] In step (1) of the preparation method of the lithium-rich manganese-based precursor, the molar ratio of cerium chloride, lanthanum chloride and bismuth chloride in the salt of the doping metal M in the mixed solution is 2:1:1, and the rest is the same as in example 1.

[0155] The embodiment further provides a lithium-rich manganese-based positive electrode material, wherein the lithium-rich manganese-based precursor in step (I) in the preparation process of the lithium-rich manganese-based precursor is replaced by the lithium-rich manganese-based precursor in the embodiment, and the rest is the same as in example 1.

[0156] Example 10

[0157] The embodiment provides a lithium-rich manganese-based precursor, wherein M includes Ce, La and Bi in a molar ratio of 1:0.2:1.

[0158] The preparation method of the lithium-rich manganese-based precursor is as follows: in step (1), the molar ratio of cerium chloride, lanthanum chloride and bismuth chloride in the doped metal M salt in the mixed solution is 1:0.2:1, and the rest is the same as in example 1.

[0159] The lithium-rich manganese-based positive electrode material is prepared by the preparation process of the lithium-rich manganese-based precursor, and the lithium-rich manganese-based precursor in step (I) is replaced by the lithium-rich manganese-based precursor in the embodiment.

[0160] Example 11

[0161] The lithium-rich manganese-based precursor is prepared by the preparation method of the lithium-rich manganese-based precursor, and the lithium-rich manganese-based precursor in step (I) is replaced by the lithium-rich manganese-based precursor in the embodiment.

[0162] The preparation method of the lithium-rich manganese-based precursor is as follows: in step (1), the molar ratio of cerium chloride, lanthanum chloride and bismuth chloride in the doped metal M salt in the mixed solution is 1:2:1, and the rest is the same as in example 1.

[0163] The lithium-rich manganese-based positive electrode material is prepared by the preparation process of the lithium-rich manganese-based precursor, and the lithium-rich manganese-based precursor in step (I) is replaced by the lithium-rich manganese-based precursor in the embodiment.

[0164] Example 12

[0165] The lithium-rich manganese-based precursor is prepared by the preparation method of the lithium-rich manganese-based precursor, and the lithium-rich manganese-based precursor in step (I) is replaced by the lithium-rich manganese-based precursor in the embodiment.

[0166] The lithium-rich manganese-based positive electrode material is prepared by the preparation process of the lithium-rich manganese-based precursor, and the lithium-rich manganese-based precursor in step (I) is replaced by the lithium-rich manganese-based precursor in the embodiment.

[0167] Example 13

[0168] The lithium-rich manganese-based precursor is prepared by the preparation method of the lithium-rich manganese-based precursor, and the lithium-rich manganese-based precursor in step (I) is replaced by the lithium-rich manganese-based precursor in the embodiment.

[0169] The lithium-rich manganese-based positive electrode material is prepared by the preparation process of the lithium-rich manganese-based precursor, and the lithium-rich manganese-based precursor in step (I) is replaced by the lithium-rich manganese-based precursor in the embodiment.

[0170] Example 14

[0171] The embodiment provides a lithium-rich manganese-based precursor, which is the same as that in Embodiment 1 except that the mass fraction of ammonium chloride in the mixed solution in step (1) of the preparation method of the lithium-rich manganese-based precursor is 30 wt%.

[0172] The embodiment further provides a lithium-rich manganese-based positive electrode material, which is the same as that in Embodiment 1 except that the lithium-rich manganese-based precursor in step (I) of the preparation process of the lithium-rich manganese-based precursor is replaced by the lithium-rich manganese-based precursor in the embodiment.

[0173] Embodiment 15

[0174] The embodiment provides a lithium-rich manganese-based precursor, which is the same as that in Embodiment 1 except that the mass fraction of ammonium chloride in the mixed solution in step (1) of the preparation method of the lithium-rich manganese-based precursor is 30 wt%.

[0175] The embodiment further provides a lithium-rich manganese-based positive electrode material, which is the same as that in Embodiment 1 except that the lithium-rich manganese-based precursor in step (I) of the preparation process of the lithium-rich manganese-based precursor is replaced by the lithium-rich manganese-based precursor in the embodiment.

[0176] Embodiment 16

[0177] The embodiment provides a lithium-rich manganese-based precursor, which is the same as that in Embodiment 1 except that the air compression pressure in step (2) of the preparation method of the lithium-rich manganese-based precursor is 0.05 MPa.

[0178] The embodiment further provides a lithium-rich manganese-based positive electrode material, which is the same as that in Embodiment 1 except that the lithium-rich manganese-based precursor in step (I) of the preparation process of the lithium-rich manganese-based precursor is replaced by the lithium-rich manganese-based precursor in the embodiment.

[0179] Embodiment 17

[0180] The embodiment provides a lithium-rich manganese-based precursor, which is the same as that in Embodiment 1 except that the air compression pressure in step (2) of the preparation method of the lithium-rich manganese-based precursor is 1 MPa.

[0181] The embodiment further provides a lithium-rich manganese-based positive electrode material, which is the same as that in Embodiment 1 except that the lithium-rich manganese-based precursor in step (I) of the preparation process of the lithium-rich manganese-based precursor is replaced by the lithium-rich manganese-based precursor in the embodiment.

[0182] Embodiment 18

[0183] The embodiment provides a lithium-rich manganese-based positive electrode material, which is the same as that in Embodiment 1 except that the thickness of the lithium phosphate layer in the lithium-rich manganese-based positive electrode material is 1 nm.

[0184] Comparative Example 1

[0185] The present comparative example provides a lithium-rich manganese-based precursor, wherein M comprises titanium, iron and magnesium in a molar ratio of 1:1:1.

[0186] The present comparative example provides a lithium-rich manganese-based precursor, wherein M comprises titanium, iron and magnesium in a molar ratio of 1:1:1.

[0187] The present comparative example also provides a lithium-rich manganese-based positive electrode material, wherein the lithium-rich manganese-based precursor in step (I) in the preparation process of the lithium-rich manganese-based precursor is replaced by the lithium-rich manganese-based precursor in the present comparative example.

[0188] Comparative Example 2

[0189] The present comparative example provides a lithium-rich manganese-based precursor, wherein M comprises cerium and bismuth in a molar ratio of 1:1.

[0190] The present comparative example provides a lithium-rich manganese-based precursor, wherein M comprises cerium and bismuth in a molar ratio of 1:1.

[0191] The present comparative example also provides a lithium-rich manganese-based positive electrode material, wherein the lithium-rich manganese-based precursor in step (I) in the preparation process of the lithium-rich manganese-based precursor is replaced by the lithium-rich manganese-based precursor in the present comparative example.

[0192] Comparative Example 3

[0193] The present comparative example provides a lithium-rich manganese-based precursor, wherein M comprises cerium and lanthanum in a molar ratio of 1:1.

[0194] The present comparative example provides a lithium-rich manganese-based precursor, wherein M comprises cerium and lanthanum in a molar ratio of 1:1.

[0195] The present comparative example also provides a lithium-rich manganese-based positive electrode material, wherein the lithium-rich manganese-based precursor in step (I) in the preparation process of the lithium-rich manganese-based precursor is replaced by the lithium-rich manganese-based precursor in the present comparative example.

[0196] Comparative Example 4

[0197] The present comparative example provides a lithium-rich manganese-based precursor, wherein M comprises lanthanum and bismuth in a molar ratio of 1:1.

[0198] The step (1) of the preparation method of the lithium-rich manganese-based precursor is replaced by doping metal M salt with equivalent molar amount of doped metal M salt (including molar ratio of 1:1 of lanthanum chloride and bismuth chloride), and the rest is the same as example 1.

[0199] The present comparative example also provides a lithium-rich manganese-based positive electrode material, wherein, except that the lithium-rich manganese-based precursor in step (I) of the preparation process of the lithium-rich manganese-based precursor is replaced by the lithium-rich manganese-based precursor in the present comparative example, the rest is the same as example 1.

[0200] Comparative example 5

[0201] The present comparative example provides a lithium-rich manganese-based precursor, wherein the lithium-rich manganese-based precursor has a composition of Mn 0.6 Ni 0.4 O2, the lithium-rich manganese-based precursor does not contain doped element M; the specific surface area of the lithium-rich manganese-based precursor is 5 m 2 / g;

[0202] The preparation method of the lithium-rich manganese-based precursor is as follows:

[0203] (1) mixing manganese chloride, nickel chloride, sodium dodecyl sulfate, ammonium chloride and water to obtain a mixed solution;

[0204] The molar ratio of manganese chloride to nickel chloride in the mixed solution is 0.6:0.38, and the mass concentration of total metal ions is 150 g / L; the mass fraction of sodium dodecyl sulfate in the mixed solution is 2 wt%, and the mass fraction of ammonium chloride is 15 wt% based on 100% of the mass of the mixed solution;

[0205] (2) using the obtained mixed solution as raw material to perform spray pyrolysis, and the spray pyrolysis is divided into two stages; the temperature of the first stage pyrolysis in the spray pyrolysis is 550°C, and the temperature of the second stage pyrolysis is 800°C; the frequency of the fan in the spray pyrolysis is 20 Hz, the feeding flow rate is 8 L / h, and the compressed air pressure is 0.4 MPa;

[0206] The spray pyrolysis is naturally cooled to 25°C, then the material after the spray pyrolysis is taken out, washed with hot water for 3 times, dried in an oven at 150°C for 24 h, and then sequentially screened and de-ironed to obtain the lithium-rich manganese-based precursor.

[0207] The present comparative example also provides a lithium-rich manganese-based positive electrode material, wherein, except that the lithium-rich manganese-based precursor in step (I) of the preparation process of the lithium-rich manganese-based precursor is replaced by the lithium-rich manganese-based precursor in the present comparative example, the rest is the same as example 1.

[0208] The lithium-rich manganese-based positive electrode material provided by the above examples and comparative examples is mixed with Li7P3S11 Solid electrolyte, carbon nanotubes and polyvinylidene fluoride are mixed in a mass ratio of 75:20:3:2 to form a slurry, which is then coated onto an aluminum foil current collector. After drying and cold pressing, it is made into a positive electrode sheet, which is then assembled with a lithium metal negative electrode and a solid electrolyte to form an all-solid-state battery.

[0209] Then, electrochemical performance testing was conducted. The electrochemical performance testing was carried out in a constant temperature environment of 25℃. The Blue Electric testing system was used. The first charge and discharge was carried out at a rate of 0.5C and a voltage range of 2.0-4.8V, with 200 cycles. The specific capacity of the all-solid-state battery at the first discharge of 0.5C and the capacity retention rate after 200 cycles at 0.5C are shown in Table 1.

[0210] Table 1

[0211]

[0212]

[0213] From Table 1, we can obtain:

[0214] (1) The lithium-rich manganese-based cathode material prepared by the lithium-rich manganese-based precursor provided in Examples 1 to 5 of the present invention has excellent performance, and the battery prepared by the lithium-rich manganese-based cathode material exhibits high discharge specific capacity and excellent cycle stability.

[0215] Among them, a comparison of Examples 1 with Examples 4 and 5 shows that when M includes Ce, La, and Bi, the battery exhibits superior performance; the doping of these three elements can synergistically achieve redox buffering, lattice anchoring, and surface energy modulation of the lithium-rich manganese-based precursor; Redox buffer: Ce 4+ With Ce 3+ Reversible energy change regulates local charge balance and inhibits metal particle aggregation; lattice anchoring: La 3+ (ionic radius) It can pin grain boundaries, hindering grain migration; surface energy modulation: Bi 3+ with Bi 5+ The 6p lone pair induces surface reconstruction, forming a bond length gradient with the support (such as the Bi-O bond length). This improves the uniformity of metal precursors;

[0216] (2) Through the comparison of Example 1 and Examples 6 and 7, it can be seen that in the present application, the content of the doping element M affects the performance of the lithium-rich manganese-based precursor, the lithium-rich manganese-based positive electrode material and the battery; when 0.005≤1-a-b≤0.05, the battery exhibits more excellent performance, which is because by limiting 0.005≤1-a-b≤0.05, the total content of the doping element M can be accurately controlled; too low, it is difficult to play a synergistic effect, and it is difficult to effectively optimize the structural stability and ion transmission; too high, it is easy to cause lattice distortion and destroy the main structure; when 0.005≤1-a-b≤0.05, M can not only improve the precursor performance by regulating the Zeta potential, pinning the grain boundary, but also does not affect the integrity of the main structure, thereby achieving the balance optimization of the discharge specific capacity and the cycle stability of the battery;

[0217] (3) Through the comparison of Example 1 and Examples 8-11, it can be seen that in the present application, when the molar ratio of Ce, La and Bi in M is (0.5-1.5):(0.5-1.5):1, the battery exhibits more excellent performance, which is because by limiting the molar ratio of Ce, La and Bi, the synergistic effect intensity of the three can be accurately regulated, the charge buffer capacity of Ce, the grain boundary pinning effect of La and the surface reconstruction effect of Bi form the optimal matching, which not only avoids the lattice distortion caused by the excessive single element, but also ensures the functional complementation, thereby stabilizing the structure of the lithium-rich manganese-based precursor and improving the ion transmission efficiency, and finally realizing the synergistic optimization of the discharge specific capacity and the cycle stability;

[0218] (4) Through the comparison of Example 1 and Examples 12 and 13, it can be seen that in the preparation method of the lithium-rich manganese-based precursor provided by the present application, the first additive affects the performance of the lithium-rich manganese-based precursor, the lithium-rich manganese-based positive electrode material and the battery; when the mass fraction of the first additive in the mixed solution is 0.1wt%-5wt%, the battery exhibits more excellent performance, which is because under this mass fraction, the first additive can effectively regulate the surface tension of the solution, promote the uniform dispersion of metal ions, inhibit the agglomeration of precursor particles, and form a micro-nano structure with uniform size; at the same time, it can also optimize the particle morphology in the spray pyrolysis process, reduce the pore collapse, improve the specific surface area and structural stability, thereby enhancing the cycle stability of the battery;

[0219] (5) Through the comparison of Example 1 and Examples 14 and 15, it can be seen that in the present application, by adding an appropriate amount of ammonium chloride in the mixing, because ammonium chloride has a low boiling point, it is easy to volatilize in the spray pyrolysis, so that more pores will be formed in the lithium-rich manganese-based precursor, and a lithium-rich manganese-based precursor with pores is obtained;

[0220] (6) Through the comparison of Example 1 and Examples 16 and 17, it can be seen that in the preparation method of the lithium-rich manganese-based precursor provided by the application, the compressed air pressure during spray pyrolysis affects the performance of the lithium-rich manganese-based precursor, the lithium-rich manganese-based positive electrode material and the battery; when the compressed air pressure is 0.1 MPa-0.8 MPa, the battery exhibits more excellent performance, which is because under the range of the compressed air pressure, the atomized droplet size and distribution can be optimized to form precursor particles with uniform particle size; at the same time, the pyrolysis reaction is promoted to proceed fully, avoiding excessive agglomeration of the particles or collapse of the pore structure, so that the lithium-rich manganese-based precursor has a high specific surface area while also having certain porosity; therefore, the battery exhibits more excellent performance;

[0221] (7) Through the comparison of Example 1 and Comparative Examples 1-4, it can be seen that in the lithium-rich manganese-based precursor provided by the application, the doping element M is introduced, the doping element M includes a combination of at least three of Zr, Ru, Ga, B, Pb, As, Ba, Ce, La, Bi or Pt, and the doping of the doping element M shortens the Mn-O bond length, improving the structural stability of the lithium-rich manganese-based precursor;

[0222] In the lithium-rich manganese-based precursor provided by the application, the introduction of the doping element M significantly improves the composition uniformity and size uniformity of the lithium-rich manganese-based precursor; the doping element M promotes the more uniform dispersion of manganese, nickel and doped metal ions in the liquid phase by adjusting the Zeta potential of the raw material system, thereby improving the composition uniformity of the lithium-rich manganese-based precursor, in addition, the segregation of the doping element M at the grain boundaries forms a eutectic phase, effectively inhibiting the abnormal growth of the crystal grains, so that the lithium-rich manganese-based precursor has more uniform grain size. Therefore, the lithium-rich manganese-based precursor with higher composition uniformity and size uniformity inhibits stress concentration caused by composition segregation and non-uniform grain size, enhances the structural uniformity of the lithium-rich manganese-based precursor, thereby inhibiting the structural collapse of the lithium-rich manganese-based positive electrode material during the cycle process, and improving the cycle stability of the battery;

[0223] The lithium-rich manganese-based precursor provided by the application has porosity and a relatively high specific surface area, thereby improving the lithium ion diffusion rate of the lithium-rich manganese-based positive electrode material prepared from the lithium-rich manganese-based precursor; the porosity of the lithium-rich manganese-based positive electrode material provides sufficient channels for electrolyte penetration, increasing the contact area of the electrode and the electrolyte; the relatively high specific surface area increases the active reaction sites, which helps to speed up the lithium ion insertion and extraction process, thereby improving the discharge specific capacity of the lithium-rich manganese-based positive electrode material.

[0224] The above merely describes specific embodiments of the application, but the protection scope of the application is not limited thereto, and those skilled in the art should understand that any changes or replacements within the technical scope disclosed by the application can be easily conceived by those skilled in the art, and all fall within the protection scope and disclosure scope of the application.

Claims

1. A lithium-rich manganese-based precursor, characterized in that, The lithium-rich manganese-based precursor has a composition of Mn. a Ni b M 1-a-b O2, where 0.55≤a≤0.75, 0.2≤b≤0.4; wherein M includes at least three of Zr, Ru, Ga, B, Pb, As, Ba, Ce, La, Bi or Pt; The specific surface area of ​​the lithium-rich manganese-based precursor is not less than 10 m². 2 / g.

2. The lithium-rich manganese-based precursor according to claim 1, characterized in that, 0.005≤1-ab≤0.05; Preferably, M includes Ce, La, and Bi; Preferably, the molar ratio of Ce, La and Bi in M ​​is (0.5-1.5):(0.5-1.5):

1.

3. A method for preparing the lithium-rich manganese-based precursor according to claim 1 or 2, characterized in that, The preparation method includes: A mixed solution was obtained by mixing manganese salt, nickel salt, doped metal M salt, additives and solvent; the resulting mixed solution was then used as a raw material for spray pyrolysis to obtain a lithium-rich manganese-based precursor. The doped metal M salt includes a combination of at least three of the following: Zr salt, Ru salt, Ga salt, B salt, Pb salt, As salt, Ba salt, Ce salt, La salt, Bi salt, or Pt salt.

4. The preparation method according to claim 3, characterized in that, The mixing process also includes the inclusion of additives; Preferably, the additive comprises a first additive and a second additive; the first additive comprises any one or a combination of at least two of sodium dodecyl sulfate, polysorbate-80, or alkyl glycoside; the second additive comprises ammonium chloride; Preferably, the molar ratio of manganese salt, nickel salt and doped metal M salt in the mixed solution is (55-75):(20-40):(0.5-5); Preferably, the total metal ion concentration in the mixed solution is 50 g / L to 250 g / L; Preferably, the mass fraction of the first additive in the mixed solution is 0.1 wt% to 5 wt%, based on the mass of the mixed solution. Preferably, the mass fraction of the second additive in the mixed solution is 10 wt% to 20 wt%, based on the mass of the mixed solution.

5. The preparation method according to claim 3, characterized in that, The spray pyrolysis is carried out in two stages; the temperature of the first stage of spray pyrolysis is 200℃~500℃, and the temperature of the second stage of pyrolysis is 600℃~1000℃. Preferably, the fan frequency during spray pyrolysis is 0Hz to 50Hz; Preferably, the feed flow rate during spray pyrolysis is 2 L / h to 15 L / h; Preferably, the compressed air pressure during spray pyrolysis is 0.1 MPa to 0.8 MPa.

6. A lithium-rich manganese-based cathode material, characterized in that, The lithium-rich manganese-based cathode material is prepared from raw materials containing the lithium-rich manganese-based precursor as described in claim 1 or 2.

7. The lithium-rich manganese-based cathode material according to claim 6, characterized in that, The lithium-rich manganese-based cathode material includes a cathode material core and a lithium phosphate layer covering the cathode material core. Preferably, the D50 particle size of the cathode material core is 100nm to 1000nm; Preferably, the thickness of the lithium phosphate layer is 1 nm to 10 nm.

8. A preparation process for the lithium-rich manganese-based cathode material according to claim 6 or 7, characterized in that, The preparation process includes: The lithium-rich manganese-based precursor described in claim 1 or 2 is mixed with a lithium source and then sintered in a solid state to obtain a cathode material core. A lithium phosphate layer is then deposited on the outside of the obtained cathode material core by atomic layer deposition to obtain a lithium-rich manganese-based cathode material.

9. The preparation process according to claim 8, characterized in that, In the mixture, the molar ratio of total metal elements in the lithium-rich manganese-based precursor to lithium elements in the lithium source is 1:(1.0-1.5). Preferably, the solid-state sintering temperature is 550℃~950℃, and the time is 2h~24h; Preferably, in the atomic layer deposition, the reaction temperature is set to 100℃~500℃, and the number of cycles is 10 to 100. Preferably, the lithium source transported in the atomic layer deposition includes any one or a combination of at least two of tert-butyllithium, n-butyllithium, isobutyllithium, or methyllithium; Preferably, in the atomic layer deposition, the temperature of the lithium deposition source is 100℃~200℃, and the pulse duration of the lithium deposition source is 500ms~2000ms; Preferably, the phosphorus source used in the atomic layer deposition includes any one or a combination of at least two of trimethyl phosphate, triethyl phosphate, trimethylphosphorus, or triisopropyl phosphate. Preferably, in the atomic layer deposition, the temperature of the deposited phosphorus source is 30℃~80℃, and the pulse duration of the deposited phosphorus source is 50ms~500ms; Preferably, the atomic layer deposition is followed by annealing, which is carried out in a protective atmosphere at a temperature of 250°C to 350°C for 0.5 h to 1.5 h.

10. A battery, characterized in that, The battery comprises the lithium-rich manganese-based cathode material as described in claim 6 or 7.

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