A lithium nickel manganese oxide coated high-nickel ternary positive electrode material and a preparation method thereof

Abstract

A kind of lithium nickel manganese oxide coated high-nickel ternary positive electrode material and preparation method thereof, the positive electrode material is by spinel lithium nickel manganese oxide coating layer with mass ratio 0.005~0.040:1 coated high-nickel ternary positive electrode material to form spherical particle;High-nickel ternary positive electrode material chemical formula is LiNi x Co y Mn (1‑x‑y) O2, wherein 0.75≤x≤0.90, 0.05≤y≤0.15, 1-x-y>0.The preparation method comprises: (1) high-nickel ternary positive electrode material is added to the organic solution containing nickel, manganese, lithium, and stirred mixing;(2) drop the precipitant organic solution, stir the reaction, heat stirring to steam dry, grinding;(3) sintering under oxidizing atmosphere, cooling, it is finished.The positive electrode material of the application is highly reversible in charge-discharge reaction, stable in structure, has good rate performance and cycle stability.The method of the application is simple, short in process, good in coating effect, low in cost, and suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to a high-nickel ternary positive electrode material and a preparation method thereof, and in particular to a lithium nickel manganese oxide-coated high-nickel ternary positive electrode material and a preparation method thereof. Background Art

[0002] With the dwindling reserves of non-renewable resources, lithium-ion batteries, with their significant advantages such as high operating voltage, high specific capacity, and environmental friendliness, have become widely used in the new energy transportation sector. The rapid development of electric vehicles has also placed higher demands on battery energy density, making high-nickel ternary cathode materials for lithium-ion batteries—nickel-cobalt-manganese / lithium-aluminate (NCM / NCA)—a key research topic. However, the greatest drawback of high-nickel ternary materials is their poor structural stability and high-temperature performance. Their surface particles are prone to phase transitions from layered structure to spinel structure to inactive rock salt phase, resulting in capacity and cycling performance degradation. These issues severely hinder their large-scale application. Their poor cycling performance is closely related to the matrix structure and surface and interface properties, a challenge that urgently needs to be addressed. Therefore, the modification of ternary materials is crucial.

[0003] CN115425214A discloses a lithium titanium aluminum phosphate coated modified lithium ion battery high nickel ternary positive electrode material and preparation method, wherein a phosphorus source, an aluminum source, a lithium source, a titanium source and an additive are sequentially dispersed in a first solvent, the obtained coated suspension is subjected to a first ball milling, the obtained coated slurry is subjected to a first drying, the obtained lithium titanium aluminum phosphate precursor is mixed with the high nickel ternary positive electrode material and the second solvent after the second ball milling and subjected to a third ball milling, and the obtained mixed slurry is sequentially subjected to a second drying and sintering to obtain a coated modified high nickel ternary positive electrode material. Although this method can increase the lithium ion diffusion rate during charge and discharge, and effectively reduce the erosion of the electrolyte on the positive electrode material body, reduce the battery impedance, and improve the cycle stability of the positive electrode material, in actual operation, the control conditions are relatively strict, and it is necessary to undergo multiple treatments, and the purity of the obtained lithium titanium aluminum phosphate is low, which is not good for the subsequent lithium titanium aluminum phosphate coated high nickel ternary material.

[0004] CN111600014A discloses a solid electrolyte LATP coated modified lithium ion battery high nickel ternary positive electrode material and preparation method, which is to dissolve lithium salt and aluminum salt in water according to the molar ratio of various elements in the solid electrolyte LATP to obtain a clear and transparent solution, add titanium salt, stir, and then add citric acid until a clear and transparent solution is obtained, add high nickel ternary positive electrode material and phosphate aqueous solution, stir, filter, dry, and heat treat to obtain a high nickel ternary positive electrode material coated with a solid electrolyte. Although this method can suppress the side reaction between the positive electrode material and the electrolyte, there may be a chemical reaction at the interface between the solid electrolyte and the high nickel ternary material, resulting in a decrease in the electrochemical stability of the material and affecting the cycle life and safety of the battery; in addition, the interface bonding between the solid electrolyte and the high nickel ternary material may not be strong enough, and the material is prone to peeling and damage during the cycle.

[0005] CN114229917A discloses a coating agent containing the elements W, Al, and B, which is used to coat and modify a high-nickel ternary cathode material for lithium-ion batteries, and a preparation method. The high-nickel ternary cathode material is first pickled to remove residual alkali, and then mixed with a coating agent containing the elements W, Al, and B and sintered. W and B enter the grain boundaries, filling the grain boundaries to reduce the specific surface area of ​​the material, and Al is used to increase the stability of the material interface. Although sintering can significantly improve the capacity and cycle stability of the material, acidic substances may remain on the surface of the material after pickling. These residues will continue to react with the material, damaging the structure and performance of the material in the later stages of the cycle.

[0006] CN114566647A discloses a method for preparing a calcium phosphate-coated high-nickel ternary cathode material. The method comprises adding a calcium source solution to an organic solvent or water, stirring the mixture, then adding the high-nickel ternary cathode material and a phosphorus source solution, heating, and drying the mixture to obtain a powder material. The powder material is then calcined to obtain the calcium phosphate-coated high-nickel ternary cathode material. Although sintering the surface of the high-nickel ternary cathode material after coating it with calcium phosphate can effectively reduce residual lithium on the surface of the high-nickel ternary material, reduce the occurrence of side reactions, and improve its storage performance, the structural compatibility between the phosphate-coated material and the high-nickel ternary material may not be ideal, which may lead to an unstable interface or the formation of an uneven coating layer, which will affect the material's conductivity and ion migration ability.

[0007] CN108777291A discloses a method for preparing a lithium manganate-coated high-nickel ternary lithium battery cathode material. The method involves ball milling an NCM811 precursor with Mn2O7 and Na2S2O8. The NCM811 precursor is oxidized to NCMOOH, and the surface is coated with MnO2 and Na2SO4 formed by reduction of Mn2O7. The Na2SO4 and Na2S2O8 are then eluted with anhydrous ethanol. The water and acid in the decomposition products are absorbed by Mn2O7 and residual alkali on the surface, respectively, to form a MnO2-coated NCMOOH material. This is then sintered with an added lithium source to form a LiMn2O4-coated NCM811 cathode material. Although this method can reduce nickel-lithium mixing and surface residual alkali, improving the battery's reversible capacity and stability, the precursor oxidation process and subsequent reactions are uncontrollable, making coating uniformity and experimental repeatability difficult to ensure.

[0008] In summary, it is urgent to find a lithium nickel manganese oxide coated high nickel ternary positive electrode material with good conductivity during the charge and discharge process, highly reversible charge and discharge reaction, stable thermodynamic structure, high safety, good rate performance and cycle stability, as well as a preparation method for lithium nickel manganese oxide coated high nickel ternary positive electrode material that is simple and controllable, has a short process flow, good coating effect, low cost, and is suitable for industrial production. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a lithium nickel manganese oxide-coated high-nickel ternary positive electrode material with good conductivity during the charge and discharge process, highly reversible charge and discharge reactions, stable thermodynamic structure, high safety, good rate performance and cycle stability.

[0010] The technical problem to be further solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for preparing a lithium nickel manganese oxide-coated high-nickel ternary positive electrode material that is simple and controllable, has a short process flow, good coating effect, low cost, and is suitable for industrial production.

[0011] The technical solution adopted by the present invention to solve the technical problem is as follows: a lithium nickel manganese oxide coated high nickel ternary positive electrode material, the lithium nickel manganese oxide coated high nickel ternary positive electrode material is a spherical particle formed by coating a high nickel ternary positive electrode material with a spinel type lithium nickel manganese oxide coating layer at a mass ratio of 0.005 to 0.040:1 (more preferably 0.008 to 0.030:1); the chemical formula of the high nickel ternary positive electrode material is LiNi x Co y Mn (1-x-y) O2, wherein 0.75≤x≤0.90 (more preferably 0.80≤x≤0.85), 0.05≤y≤0.15 (more preferably 0.08≤y≤0.11), 1-xy>0. Spinel-type lithium nickel manganese oxide LiNi 0.5 Mn1.5 O4 has a three-dimensional large tunnel structure, good conductivity, and is very suitable for lithium ion diffusion. At the same time, it also has a very stable thermodynamic structure in the charged state. The present invention creatively proposes to use high-voltage spinel structure lithium nickel manganese oxide to coat high-nickel ternary positive electrode materials, which can improve the electrochemical performance to varying degrees, so that it can give full play to the advantages of high working voltage and fast charging and discharging of lithium nickel manganese oxide during the cycle process. After being coated with an appropriate amount of lithium nickel manganese oxide material, the high-nickel ternary positive electrode material can not only improve the cycle stability during the charge and discharge cycle, but also ensure the rapid deintercalation reaction of the layered structure high-nickel ternary positive electrode material; the present invention selects a suitable lithium nickel manganese oxide coating material to uniformly coat the surface of the high-nickel ternary positive electrode material, which can better inhibit the erosion of the electrolyte, reduce the degree of cation mixing, inhibit phase change, increase the stability of the material structure, and reduce electrode polarization. At the same time, lithium nickel manganese oxide has an efficient three-dimensional lithium ion diffusion path, thereby significantly improving the problems of short cycle life and poor high-rate discharge performance of the material, and exhibiting excellent electrochemical properties.

[0012] Preferably, the high-nickel ternary positive electrode material is a typical α-NaFeO2 layered structure.

[0013] Preferably, the average particle size of the lithium nickel manganese oxide-coated high-nickel ternary cathode material is 10 to 20 μm. When the secondary particles of the lithium nickel manganese oxide-coated high-nickel ternary cathode material are within this particle size, they can not only ensure rapid lithium ion diffusion kinetics but also prevent material agglomeration during storage.

[0014] Preferably, the average thickness of the spinel lithium nickel manganese oxide coating is 2 to 6 nm. The coating should not be too thick or too thin. A too thick coating can lead to poor contact between particles and increase interfacial impedance; while a too thin coating may not effectively protect the electrode material, easily leading to degradation of the material structure and electrochemical performance.

[0015] The present invention further solves the technical problem by adopting the following technical solution: a method for preparing a lithium nickel manganese oxide coated high nickel ternary positive electrode material, comprising the following steps:

[0016] (1) adding a high nickel ternary cathode material to an organic solution containing nickel, manganese and lithium, stirring and mixing, and obtaining a high nickel ternary cathode material mixed metal ion dispersion;

[0017] (2) slowly adding a precipitant organic solution to the mixed metal ion dispersion of the high-nickel ternary cathode material obtained in step (1), stirring for reaction, heating and stirring until evaporated to dryness, and grinding to obtain a lithium nickel manganese oxide precursor coated high-nickel ternary cathode material;

[0018] (3) coating the lithium nickel-manganese oxide precursor obtained in step (2) on the high-nickel ternary positive electrode material, sintering in an oxidizing atmosphere, and cooling to room temperature to obtain the lithium nickel-manganese oxide coated high-nickel ternary positive electrode material.

[0019] The inventive idea of the method is that, under the action of the precipitating agent in the organic solvent, nickel, manganese and lithium ions undergo a co-precipitation reaction to form a lithium nickel-manganese oxide precursor coating layer on the surface of the high-nickel ternary positive electrode material, and then a high-temperature solid-phase reaction is performed to form the lithium nickel-manganese oxide coated high-nickel ternary positive electrode material. Since the amount of the lithium nickel-manganese oxide coating is small, if the lithium nickel-manganese oxide coated material is directly mixed with the high-nickel ternary positive electrode material powder, the coating layer will be uneven. Therefore, the co-precipitation method can achieve uniform coating of the lithium nickel-manganese oxide on the surface of the high-nickel ternary positive electrode material.

[0020] Preferably, in step (1), the mass-to-volume ratio g / mL of the high-nickel ternary positive electrode material to the organic solution containing nickel, manganese and lithium is 0.2-0.5:10. If the solid-to-liquid ratio is too high, the adhesion of the coating agent will be reduced, forming a loose coating layer; if the solid-to-liquid ratio is too low, the coating layer may not be stable and easily fall off, reducing the long-term stability of the material. Therefore, a moderate solid-to-liquid ratio can better ensure that the coated material adheres to the surface of the high-nickel ternary material to form a uniform and stable coating layer, which is crucial for improving the cycle performance and thermal stability of the battery.

[0021] Preferably, in step (1), the average particle size of the high-nickel ternary positive electrode material is 10-20 μm. At this particle size, the high-nickel ternary positive electrode material has a good morphology, uniform dispersion and stable electrochemical performance.

[0022] Preferably, in step (1), the total molar concentration of nickel, manganese and lithium ions in the organic solution containing nickel, manganese and lithium is 5-15 mmol / L.

[0023] Preferably, in step (1), the molar ratio of nickel, manganese and lithium ions in the organic solution containing nickel, manganese and lithium is 1:2.8-3.2:1.8-2.2.

[0024] The above concentrations and molar ratios not only ensure that the coated material meets the design values of each element under different coating amounts, but also control the amount of solvent within a reasonable range, allowing the reactants to be uniformly mixed and accelerating the reaction rate, thereby obtaining a more uniform and pure product.

[0025] Preferably, in step (1), the stirring and mixing temperature is room temperature, the stirring speed is 300-600 r / min, and the time is 1-3 h. Stirring and mixing under the above conditions can ensure that the high-nickel ternary positive electrode material is uniformly dispersed in the organic solution containing nickel, manganese, and lithium; wherein, the appropriate rotation speed helps to improve the dispersibility of the coating material on the surface of the high-nickel ternary material, so that the coating material is uniformly deposited on the surface of the particles, which is very important for obtaining a uniform and stable coating layer; in addition, stirring at room temperature for a certain time can achieve uniform dispersion of the high-nickel ternary positive electrode material, avoiding incomplete coating caused by rapid reaction after direct heating.

[0026] Preferably, in step (1), the preparation method of the high-nickel ternary positive electrode material is: grinding and mixing the nickel cobalt manganese hydroxide precursor and the lithium source, sintering them in an oxidizing atmosphere, and cooling them to room temperature.

[0027] Preferably, the nickel cobalt manganese hydroxide precursor is prepared by coprecipitation method, and its chemical formula is Ni x Co y Mn (1-x-y) (OH)2, wherein 0.75≤x≤0.90 (more preferably 0.80≤x≤0.85), 0.05≤y≤0.15 (more preferably 0.08≤y≤0.11), and 1-xy>0.

[0028] Preferably, the average particle size of the nickel-cobalt-manganese hydroxide precursor is 10-20 μm.

[0029] Preferably, the molar ratio of the total moles of Ni, Co, and Mn in the nickel cobalt manganese hydroxide precursor to Li in the lithium source is 1:1.02-1.10.

[0030] Preferably, the lithium source includes LiOH·H2O and / or Li2CO3, etc.

[0031] Preferably, the grinding speed is 100 to 300 r / min, and the grinding time is 15 to 45 min.

[0032] Preferably, the oxidizing atmosphere includes an oxygen atmosphere and / or an air atmosphere.

[0033] Preferably, the sintering is a two-stage temperature-raising sintering process, wherein the temperature is first raised to 350-550°C (more preferably 400-500°C) at a rate of 1-10°C / min (more preferably 3-6°C / min), sintered for 2-8 hours (more preferably 3-5 hours), and then raised to 550-850°C (more preferably 700-800°C) at a rate of 1-10°C / min (more preferably 3-6°C / min) and sintered for 8-20 hours (more preferably 10-15 hours). During the two-stage temperature-raising sintering process, the temperature of the second sintering stage is higher than that of the first sintering stage. During the first sintering stage, the decomposition reaction of the high-nickel ternary precursor and the lithium source mainly occurs. During the second sintering stage, the chemical reaction of the high-nickel ternary precursor and the decomposed oxide of the lithium source in an oxygen atmosphere mainly occurs. If the sintering temperature is too high or the time is too long, the material will easily agglomerate or even clump, and it will be difficult to release capacity during the charge and discharge process. If the calcination temperature is too low or the time is too short, it will be difficult to form the desired morphology, affecting the electrochemical performance. If the heating rate is too fast, it will be difficult to ensure sufficient material reaction, especially affecting the diffusion of lithium ions into the material structure. If the heating rate is too slow, it will be unfavorable for industrial production.

[0034] Preferably, in step (1), the method for preparing the organic solution containing nickel, manganese and lithium is: adding a nickel source, a manganese source and a lithium source into an organic solvent, stirring and dissolving them.

[0035] Preferably, the total molar concentration of the nickel element in the nickel source, the manganese element in the manganese source, and the lithium element in the lithium source in the organic solution containing nickel, manganese, and lithium is 5 to 15 mmol / L.

[0036] Preferably, the molar ratio of the nickel element in the nickel source, the manganese element in the manganese source, and the lithium element in the lithium source is 1:2.8-3.2:1.8-2.2.

[0037] Preferably, the stirring and dissolving is performed at room temperature, at a stirring speed of 300 to 600 r / min, and for 2 to 6 hours. Stirring and dissolving under these conditions ensures that the nickel source, manganese source, and lithium source are fully dissolved to form a uniform organic solution containing nickel, manganese, and lithium.

[0038] Preferably, the lithium source includes one or more of lithium acetate, lithium nitrate or lithium sulfate, and hydrates thereof.

[0039] Preferably, the nickel source includes one or more of nickel acetate, nickel nitrate or nickel sulfate, and hydrates thereof.

[0040] Preferably, the manganese source includes one or more of manganese acetate, manganese nitrate or manganese sulfate, and hydrates thereof.

[0041] Preferably, the organic solvent includes one or more of anhydrous ethanol, methanol or isopropanol.

[0042] Preferably, in step (2), the slow addition rate is 1 to 10 mL / min (more preferably 2 to 6 mL / min). The precipitant addition rate affects the precipitation rate and particle size; if the addition rate is too fast, the precipitation reaction will be violent, resulting in smaller particles; within the stated addition rate range, the precipitation reaction proceeds normally, and uniform precipitation of lithium nickel manganese oxide can be achieved.

[0043] Preferably, in step (2), the molar ratio of the precipitant in the precipitant organic solution to the nickel in the high-nickel ternary positive electrode material mixed metal ion dispersion is 4 to 8:1 (more preferably 5 to 7:1). The amount of precipitant used can ensure that the precipitant is in excess of 10 to 80% relative to the total amount of transition metal elements to achieve complete precipitation of the metal elements.

[0044] Preferably, in step (2), the concentration of the precipitant organic solution is 0.008 to 0.070 mol / L (more preferably 0.01 to 0.05 mol / L). The concentration of the precipitant affects the reaction rate of the coprecipitation and the purity of the product. If the concentration of the precipitant is too high, it will cause excessive reaction, resulting in impure products or the formation of fine particles of precipitate. If the concentration of the precipitant is too low, it will result in a slow reaction rate and incomplete precipitation. Within the concentration range, a pure phase, structurally complete spinel-type lithium nickel manganese oxide coating material can be formed.

[0045] Preferably, in step (2), the precipitant comprises one or more of oxalic acid, carbonates, or hydroxides. More preferably, the carbonate contains a carbonate group, such as sodium carbonate, and the hydroxide contains a hydroxide group, such as sodium hydroxide.

[0046] Preferably, in step (2), the solvent in the precipitant organic solution includes one or more of anhydrous ethanol, acetone or isopropanol.

[0047] Preferably, in step (2), the stirring reaction temperature is room temperature, the stirring speed is 300 to 600 r / min, and the time is 2 to 6 hours. Under the stirring reaction conditions, the precipitant organic solution and the high-nickel ternary positive electrode material mixed metal ion dispersion can be ensured to be completely and evenly mixed to achieve uniform precipitation.

[0048] Preferably, in step (2), the heating and stirring until evaporated refers to heating and stirring until evaporated in a water bath at 70 to 100°C at a stirring speed of 300 to 600 r / min. By increasing the stirring temperature, the molecular motion rate of the reactants can be accelerated, collisions between the reactants can be promoted, and the crystallinity and purity of the coating material can be improved. Within the range of the heating and stirring until evaporated, the reaction can be fully carried out within a certain period of time, avoiding adverse side reactions or product instability caused by particle agglomeration or excessive reaction time.

[0049] Preferably, in step (2), the grinding speed is 100 to 300 r / min, and the grinding time is 3 to 12 min.

[0050] Preferably, in step (3), the oxidizing atmosphere includes an oxygen atmosphere and / or an air atmosphere.

[0051] Preferably, in step (3), the sintering is a two-stage temperature-raising sintering, firstly heating to 300-550°C (more preferably 400-500°C) at a rate of 2-8°C / min (more preferably 2-6°C / min), sintering for 1-4 h (more preferably 2-3 h), and then heating to 500-700°C (more preferably 550-650°C) at a rate of 2-8°C / min (more preferably 2-6°C / min), sintering for 2-8 h (more preferably 3-6 h). First, by pre-sintering at low temperature for a short time, the organic solvent and moisture can be removed, and the initial reaction can be promoted. Secondly, by sintering at high temperature for a long time, the crystal growth and phase formation of the coating material can be promoted. Moreover, under the sintering system, the structural integrity of the main high-nickel ternary positive electrode material will not be affected.

[0052] The oxygen atmosphere used in the present invention is a high-purity gas with a purity of ≥99.99%.

[0053] The beneficial effects of the present invention are as follows:

[0054] (1) The lithium nickel manganese oxide coated high nickel ternary positive electrode material of the present invention is coated uniformly, and the secondary particles are spherical in morphology with an average particle size of 10 to 20 μm, which highly inherits the spherical morphology of the high nickel ternary precursor. The surface of the secondary particles is relatively rough, and many tiny particles are attached, forming a uniform lithium nickel manganese oxide coating layer with an average thickness of 2 to 6 nm;

[0055] (2) The battery assembled with the nickel manganese oxide coated high nickel ternary positive electrode material of the present invention has a first discharge capacity of up to 216.2 mAh / g, 182.5 mAh / g and 167.8 mAh / g at current densities of 0.2 C (40 mAh / g), 5 C and 10 C, respectively. This shows that the nickel manganese oxide coated high nickel ternary positive electrode material of the present invention has a three-dimensional large tunnel structure. The spinel phase nickel manganese oxide coated material with good conductivity can improve the lithium ion transmission efficiency of the high nickel ternary positive electrode material. When the current density gradually decreases from 10 C rate and cycles back to 0.2 C rate, the discharge capacity can still be as high as 213.4 mAh / g, which shows that the nickel manganese oxide coated high nickel ternary positive electrode material of the present invention can maintain structural stability during the charge and discharge process, the charge and discharge reaction is highly reversible, and the rate performance is good. At a charge and discharge voltage of 2.7 to 4.5 V, 1 C, the initial discharge specific capacity can reach as high as 203.7 mAh / g. After 200 cycles, the discharge specific capacity can still reach 158.65 mAh / g, and the retention rate can be as high as 81.43%. This shows that the lithium nickel manganese oxide-coated high-nickel ternary positive electrode material of the present invention has a stable thermodynamic structure, high safety, and good cycle stability.

[0056] (3) The method of the present invention is simple and controllable, has a short process flow, good coating effect, low cost, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 The lithium nickel manganese oxide coated LiNi of the embodiment 1 of the present invention 0.83 Co 0.11 Mn 0.06 XRD pattern of O2 cathode material;

[0058] Figure 2 The lithium nickel manganese oxide coated LiNi of the embodiment 1 of the present invention 0.83 Co 0.11 Mn 0.06 SEM image of O2 cathode material;

[0059] Figure 3 The lithium nickel manganese oxide coated LiNi of the embodiment 1 of the present invention 0.83 Co 0.11 Mn 0.06 TEM image of O2 cathode material;

[0060] Figure 4 It is a spinel structure lithium nickel manganese oxide LiNi prepared separately by the present invention. 0.5 Mn 1.5 XRD pattern of O4;

[0061] Figure 5 The lithium nickel manganese oxide coated LiNi of the embodiment 1 of the present invention 0.83 Co 0.11Mn 0.06 Rate curve of the battery assembled with O2 positive electrode material;

[0062] Figure 6 The lithium nickel manganese oxide coated LiNi of the embodiment 1 of the present invention 0.83 Co 0.11 Mn 0.06 Discharge cycle curve of the battery assembled with O2 positive electrode material;

[0063] Figure 7 The lithium nickel manganese oxide coated LiNi of Example 2 of the present invention 0.83 Co 0.11 Mn 0.06 Rate curve of the battery assembled with O2 positive electrode material;

[0064] Figure 8 The lithium nickel manganese oxide coated LiNi of Example 2 of the present invention 0.83 Co 0.11 Mn 0.06 Discharge cycle curve of the battery assembled with O2 positive electrode material;

[0065] Figure 9 The lithium nickel manganese oxide coated LiNi of Example 3 of the present invention 0.83 Co 0.11 Mn 0.06 Discharge cycle curve of the battery assembled with O2 positive electrode material;

[0066] Figure 10 The high nickel ternary LiNi 0.83 Co 0.11 Mn 0.06 Discharge cycle curve of the battery assembled with O2 positive electrode material;

[0067] Figure 11 The lithium nickel manganate coated LiNi obtained in Comparative Example 2 of the present invention 0.83 Co 0.11 Mn 0.06 Discharge cycle curve of the battery assembled with O2 positive electrode material. DETAILED DESCRIPTION

[0068] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0069] The lithium acetate, nickel acetate, manganese acetate, nickel sulfate, cobalt sulfate, manganese sulfate, sodium hydroxide, ammonia water, manganese nitrate, and lithium nitrate used in the Examples of the present invention and the Comparative Examples were all purchased from Aladdin Reagent Co., Ltd.; the purity of the high-purity oxygen used was 99.99%; the raw materials or chemical reagents used in the Examples of the present invention and the Comparative Examples, unless otherwise specified, were obtained through conventional commercial channels.

[0070] High nickel LiNi 0.83 Co 0.11 Mn 0.06 Reference Example 1 for Preparation of O2 Positive Electrode Materials

[0071] 10 g of Ni with an average particle size of 13 μm was added 0.83 Co 0.11 Mn 0.06 (OH)2 precursor (Ni 89.738 mmol, Co11.893 mmol, Mn 6.487 mmol) and 4.854 g (115.682 mmol) of lithium hydroxide monohydrate were added to an agate mortar and ground at a speed of 200 r / min for 30 min until mixed. Then, the mixture was heated to 450 °C at a rate of 5 °C / min in a high-purity oxygen atmosphere and sintered for 4 h. Then, the mixture was heated to 750 °C at a rate of 5 °C / min and sintered for 12 h. The mixture was cooled to room temperature to obtain high-nickel LiNi with an average particle size of 14 μm. 0.83 Co 0.11 Mn 0.06 O2 cathode material;

[0072] The Ni 0.83 Co 0.11 Mn 0.06 The (OH)2 precursor was prepared by the hydroxide co-precipitation method, and the specific operation was as follows:

[0073] 1) Add 1745.30 g (6.64 mol) of nickel sulfate hexahydrate, 247.41 g (0.88 mol) of cobalt sulfate heptahydrate, and 81.13 g (0.48 mol) of manganese sulfate monohydrate to 2 L of deionized water to prepare a metal ion mixed solution with a metal concentration of 4 mol / L.

[0074] 2) Add 399.96 g (10 mol) of NaOH to 2 L of deionized water to prepare a 5 mol / L precipitant solution.

[0075] 3) 2 L of the mixed metal ion solution obtained in step 1) was pumped into a reactor containing 2 L of a 2 mol / L ammonia solution and purged with argon at a flow rate of 100 mL / h. The ammonia concentration of the reaction system was adjusted to 2 mol / L with 25% ammonia water. The precipitant solution obtained in step 2) was simultaneously introduced into the reactor to adjust the pH of the reaction system to 11.45.

[0076] 4) Heat and stir at 40 °C and 800 r / min and perform coprecipitation reaction until the particle size distribution is uniform and the average particle size is 13 μm. Then stop stirring and age for 12 h. Wash, filter and dry the filter cake to obtain Ni 0.83Co 0.11 Mn 0.06 (OH)2 precursor material.

[0077] Preparation method of nickel, manganese, lithium-containing anhydrous ethanol solution Reference Example 2

[0078] 0.0068 g (0.0273 mmol) of nickel acetate tetrahydrate, 0.0201 g (0.0820 mmol) of manganese acetate tetrahydrate and 0.0038 g (0.0576 mmol) of lithium acetate were added to 30 mL of anhydrous ethanol, stirred and dissolved at room temperature at a stirring speed of 400 r / min for 4 h to obtain a nickel, manganese, lithium-containing anhydrous ethanol solution.

[0079] Preparation method of nickel, manganese, lithium-containing anhydrous ethanol solution Reference Example 3

[0080] 0.0136 g (0.0547 mmol) of nickel acetate tetrahydrate, 0.0402 g (0.1640 mmol) of manganese acetate tetrahydrate and 0.0076 g (0.1152 mmol) of lithium acetate were added to 30 mL of anhydrous ethanol, stirred and dissolved at room temperature at a stirring speed of 400 r / min for 4 h to obtain a nickel, manganese, lithium-containing anhydrous ethanol solution.

[0081] Preparation method of nickel, manganese, lithium-containing anhydrous ethanol solution Reference Example 4

[0082] 0.0072 g (0.0274 mmol) of nickel sulfate hexahydrate, 0.0206 g (0.0821 mmol) of manganese nitrate tetrahydrate and 0.0040 g (0.0580 mmol) of lithium nitrate were added to 20 mL of anhydrous ethanol, stirred and dissolved at room temperature at a stirring speed of 400 r / min for 4 h to obtain a nickel, manganese, lithium-containing anhydrous ethanol solution.

[0083] A lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material Example 1

[0084] The lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material is a spherical particle formed by a spinel-type lithium nickel manganese oxide LiNi 0.5 Mn 1.5 O4 coating layer coated with a mass ratio of 0.0105:1 to the high-nickel LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material obtained in Reference Example 1; the LiNi 0.83Co 0.11 Mn 0.06 O2 is a typical α-NaFeO2 type layered structure; the lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The average particle size of the O2 positive electrode material is 14 μm; the spinel type lithium nickel manganese oxide LiNi 0.5 Mn 1.5 The average thickness of the O4 coating layer is 2 nm.

[0085] like Figure 1 As shown, the embodiment of the present invention is lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The characteristic peaks of the O2 cathode material and the standard card of LiNiO2 (PDF#74-0919) are consistent, indicating that LiNi 0.83 Co 0.11 Mn 0.06 After O2 is coated, its structure is not destroyed and still shows a typical α-NaFeO2 layered structure.

[0086] like Figure 2 As shown, the embodiment of the present invention is lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The morphology of the O2 cathode material is well inherited from Ni 0.83 Co 0.11 Mn 0.06 The morphology of the (OH)2 precursor is that the secondary particles are spherical in structure with an average particle size of 14 μm, and a uniform lithium nickel manganese oxide coating layer is formed on the surface of the secondary particles.

[0087] like Figure 3 As shown, the embodiment of the present invention is lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The surface of the O2 cathode material has a spinel coating layer with an average thickness of 2 nm. The interplanar spacing d of region I is 0.201 nm, corresponding to the (104) crystal plane of the layered nickel-cobalt-manganese ternary cathode material. The interplanar spacing d of region II is 0.234 nm, corresponding to the LiNi 0.5 Mn 1.5 (222) crystal plane of O4.

[0088] A lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 Example 1 of the preparation method of O2 positive electrode material

[0089] (1) 1.0 g of the high-nickel LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material was added to 30 mL of the nickel-, manganese-, and lithium-containing ethanol solution (the concentrations of nickel, manganese, and lithium were 0.91 mmol / L, 2.73 mmol / L, and 1.92 mmol / L, respectively) obtained in Reference Example 2, and stirred at room temperature at a stirring speed of 400 r / min for 1 h to obtain a high-nickel ternary positive electrode material mixed metal ion dispersion solution;

[0090] (2) 10 mL of a 0.0164 mol / L oxalic acid ethanol solution was slowly added dropwise to 30 mL of the high-nickel ternary positive electrode material mixed metal ion dispersion solution obtained in step (1) at a speed of 2 mL / min, and stirred at room temperature at a stirring speed of 400 r / min for 4 h, and then placed in an 80 ℃ water bath, heated and stirred at a stirring speed of 500 r / min until evaporated to dryness, and ground at a rotation speed of 200 r / min for 6 min to obtain a lithium nickel-manganese oxide precursor coated high-nickel ternary positive electrode material;

[0091] (3) The lithium nickel-manganese oxide precursor coated high-nickel ternary positive electrode material obtained in step (2) was placed in a tube furnace, and first heated to 450 ℃ at a rate of 5 ℃ / min under a high-purity oxygen atmosphere, sintered for 2 h, then heated to 600 ℃ at a rate of 5 ℃ / min, sintered for 5 h, and cooled to room temperature to obtain a lithium nickel-manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material.

[0092] To prove that the material coated on the surface of LiNi 0.83 Co 0.11 Mn 0.06 O2 by steps (2) and (3) is lithium nickel-manganese oxide, the lithium nickel-manganese oxide was prepared separately by excluding the high-nickel LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material, and the specific operation was as follows:

[0093] 1) 0.2488 g (1 mmol) of nickel acetate tetrahydrate, 0.7353 g (3 mmol) of manganese acetate tetrahydrate, and 0.1386 g (2.1 mmol) of lithium acetate were added to 50 mL of ethanol, and stirred at room temperature at a stirring speed of 400 r / min for 4 h to obtain a nickel-, manganese-, and lithium-containing ethanol solution;

[0094] 2) To 50 mL of the anhydrous ethanol solution containing nickel, manganese, and lithium obtained in step 1), 15 mL of a 0.4 mol / L oxalic acid anhydrous ethanol solution was slowly added dropwise at a rate of 2 mL / min. The mixture was stirred at room temperature at a stirring rate of 400 r / min for 4 h. After that, the mixture was placed in an 80°C water bath and heated with stirring at a stirring rate of 500 r / min until evaporated to dryness. The mixture was ground at a speed of 200 r / min for 6 min. The mixture was then placed in a tubular furnace and heated to 450°C at a rate of 5°C / min in a high-purity oxygen atmosphere. After sintering for 2 h, the temperature was increased to 600°C at a rate of 5°C / min, sintered for 5 h, and cooled to room temperature to obtain lithium nickel manganese oxide.

[0095] like Figure 4 As shown, the lithium nickel manganese oxide LiNi prepared separately by the present invention 0.5 Mn 1.5 O4 has a spinel structure and LiNi 0.5 Mn 1.5 The characteristic peaks of the standard PDF card (PDF#80-2162) of O4 were consistent, and no impurities were generated.

[0096] In order to test the lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 Electrochemical properties of O2 positive electrode materials, battery assembly: weigh 0.08 g of lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material, 0.01 g acetylene black as a conductive agent and 0.01 g PVDF polyvinylidene fluoride as a binder, and N-methylpyrrolidone as a solvent were added to mix and grind to form a positive electrode material; the obtained positive electrode material was coated on the surface of aluminum foil to make a pole piece; in a closed glove box filled with argon, the pole piece was used as the positive electrode, the metal lithium sheet was used as the negative electrode, the microporous polypropylene membrane was used as the separator, and 1 mol / LLiPF6 / EC:DMC (volume ratio 1:1) was used as the electrolyte to assemble a CR2025 button battery, and the charge and discharge performance was tested.

[0097] like Figure 5 As shown, the embodiment of the present invention is lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The battery assembled with O2 positive electrode material has a discharge capacity of 216.2 mAh / g, 182.5 mAh / g and 167.8 mAh / g at 0.2C (40 mAh / g), 5 C and 10 C high rate conditions, respectively, indicating that the lithium nickel manganese oxide coated LiNi 0.83 Co0.11 Mn 0.06 O2 positive electrode material has a three-dimensional large tunnel structure, and the spinel phase lithium nickel manganese oxide coated material with good conductivity can improve the lithium ion transmission efficiency of the high-nickel ternary positive electrode material; when the current density is gradually reduced from 10 C rate and circulates back to 0.2 C rate, the discharge specific capacity can still be as high as 213.4 mAh / g, which shows that the lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material can maintain the stability of the structure during charging and discharging, and the charging and discharging reaction is highly reversible, and the rate performance is good.

[0098] As Figure 6 shown, the lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material assembled battery, under 2.7-4.5 V charging and discharging voltage, 0.1C (20 mA / g, first 3 circles) current density, the initial discharge specific capacity can be as high as 215.6 mAh / g, 1C (200 mA / g, from the 4th circle) current density, the initial discharge specific capacity is 203.7 mAh / g, after 200 cycles, the discharge specific capacity can still reach 158.3 mAh / g, and the capacity retention rate can be as high as 77.71%, which shows that the lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material has good cycle stability.

[0099] A kind of lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material example 2

[0100] The lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material is coated with spinel lithium nickel manganese oxide LiNi 0.5 Mn 1.5 O4 coating layer with mass ratio 0.021:1 to coat high-nickel LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material to form spherical particles; the LiNi 0.83 Co 0.11 Mn 0.06 O2 is a typical α-NaFeO2 type layered structure; the lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06The average particle size of the O2 positive electrode material is 14 μm; the spinel type lithium nickel manganese oxide LiNi 0.5 Mn 1.5 The average thickness of the O4 coating layer is 4 nm.

[0101] After testing, the lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The characteristic peaks of the O2 cathode material and the standard card of LiNiO2 (PDF#74-0919) are consistent, indicating that LiNi 0.83 Co 0.11 Mn 0.06 After O2 is coated, its structure is not destroyed and still shows a typical α-NaFeO2 layered structure.

[0102] After testing, the lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The morphology of the O2 cathode material is well inherited from Ni 0.83 Co 0.11 Mn 0.06 The morphology of the (OH)2 precursor is that the secondary particles are spherical in structure with an average particle size of 14 μm, and a uniform lithium nickel manganese oxide coating layer is formed on the surface of the secondary particles.

[0103] After testing, the lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The surface of the O2 cathode material has a spinel coating layer with an average thickness of 4 nm. 0.83 Co 0.11 Mn 0.06 The interplanar spacing d in the O2 cathode material region is 0.201 nm, corresponding to the (104) crystal plane of the layered ternary cathode, and the interplanar spacing d in the spinel nickel manganese oxide coating region is 0.234 nm, corresponding to the LiNi 0.5 Mn 1.5 (222) crystal plane of O4.

[0104] A lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 Example 2 of Preparation Method of O2 Positive Electrode Material

[0105] (1) 1.0 g of high nickel LiNi obtained in Reference Example 1 was added 0.83 Co 0.11 Mn 0.06The O2 positive electrode material was added to 30 mL of the anhydrous ethanol solution containing nickel, manganese, and lithium obtained in Reference Example 3 (the concentrations of nickel, manganese, and lithium were 1.82 mmol / L, 5.47 mmol / L, and 3.84 mmol / L, respectively). The mixture was stirred at room temperature and a stirring speed of 500 r / min for 2 h to obtain a high-nickel ternary positive electrode material mixed metal ion dispersion.

[0106] (2) In 30 mL of the mixed metal ion dispersion of the high-nickel ternary cathode material obtained in step (1), 10 mL of 0.0328 mol / L oxalic acid anhydrous ethanol solution was slowly added dropwise at a rate of 3 mL / min. The mixture was stirred at room temperature and a stirring speed of 500 r / min for 4 h. The mixture was then placed in a 75 °C water bath and heated and stirred at a stirring speed of 500 r / min until evaporated. The mixture was then ground at a speed of 150 r / min for 12 min to obtain a lithium nickel manganese oxide precursor-coated high-nickel ternary cathode material.

[0107] (3) The lithium nickel manganese oxide precursor obtained in step (2) is coated with a high nickel ternary positive electrode material, placed in a tube furnace, and heated to 480 ° C at a rate of 3 ° C / min in a high-purity oxygen atmosphere. After sintering for 2 h, it is heated to 580 ° C at a rate of 3 ° C / min, sintered for 5 h, and cooled to room temperature to obtain lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material.

[0108] Battery assembly: Same as Example 1.

[0109] like Figure 7 As shown, the embodiment of the present invention is lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The battery assembled with O2 positive electrode material has a discharge capacity of 204.6 mAh / g, 168.6 mAh / g and 152.2 mAh / g under the conditions of 0.2 C (40 mAh / g), 5 C and 10 C respectively, which shows that the lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The O2 positive electrode material has a three-dimensional large tunnel structure, and the spinel phase lithium nickel manganese oxide coating material with good conductivity can improve the lithium ion transmission efficiency of the high nickel ternary positive electrode material; when the current density gradually decreases from 10 C rate and cycles back to 0.2 C rate, the discharge specific capacity can still be as high as 203.5 mAh / g, indicating that the lithium nickel manganese oxide coated LiNi in the embodiment of the present invention 0.83 Co 0.11 Mn 0.06The O2 positive electrode material can maintain structural stability during the charge and discharge process, the charge and discharge reaction is highly reversible, and the rate performance is good.

[0110] like Figure 8 As shown, the embodiment of the present invention is lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The battery assembled with O2 positive electrode material has an initial discharge capacity of up to 215.0 mAh / g at a charge and discharge voltage of 2.7 to 4.5 V and a current density of 0.1 C (20 mA / g, first 3 cycles). At a current density of 1 C (200 mA / g, starting from the 4th cycle), the initial discharge capacity is 195.8 mAh / g. After 200 cycles, the discharge capacity can still reach 148.7 mAh / g, and the capacity retention rate can be as high as 75.94%, indicating that the lithium nickel manganese oxide coated LiNi in the embodiment of the present invention is effective. 0.83 Co 0.11 Mn 0.06 The O2 cathode material has good cycle stability.

[0111] A lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material embodiment 3

[0112] The lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The positive electrode material of O2 is made of spinel lithium nickel manganese oxide LiNi 0.5 Mn 1.5 The O4 coating layer is coated with the high nickel LiNi obtained in Reference Example 1 at a mass ratio of 0.0106:1 0.83 Co 0.11 Mn 0.06 Spherical particles formed by O2 positive electrode material; the LiNi 0.83 Co 0.11 Mn 0.06 O2 is a typical α-NaFeO2 type layered structure; the lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The average particle size of the O2 positive electrode material is 14 μm; the spinel type lithium nickel manganese oxide LiNi 0.5 Mn 1.5 The average thickness of the O4 coating layer is 2 nm.

[0113] After testing, the lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06The characteristic peaks of the O2 cathode material and the standard card of LiNiO2 (PDF#74-0919) are consistent, indicating that LiNi 0.83 Co 0.11 Mn 0.06 After O2 is coated, its structure is not destroyed and still shows a typical α-NaFeO2 layered structure.

[0114] After testing, the lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The morphology of the O2 cathode material is well inherited from Ni 0.83 Co 0.11 Mn 0.06 The morphology of the (OH)2 precursor is that the secondary particles are spherical in structure with an average particle size of 14 μm, and a uniform lithium nickel manganese oxide coating layer is formed on the surface of the secondary particles.

[0115] After testing, the lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The surface of the O2 cathode material has a spinel coating layer with an average thickness of 2 nm. 0.83 Co 0.11 Mn 0.06 The interplanar spacing d of the O2 cathode material region is 0.208 nm, corresponding to the (104) crystal plane of the layered ternary cathode, and the interplanar spacing d of the spinel nickel manganese oxide coating region is 0.236 nm, corresponding to the LiNi 0.5 Mn 1.5 (222) crystal plane of O4.

[0116] A lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 Example 3 of Preparation Method of O2 Positive Electrode Material

[0117] (1) 1.0 g of high nickel LiNi obtained in Reference Example 1 was added 0.83 Co 0.11 Mn 0.06 The O2 positive electrode material was added to 20 mL of the anhydrous ethanol solution containing nickel, manganese, and lithium obtained in Reference Example 4 (the concentrations of nickel, manganese, and lithium were 1.37 mmol / L, 4.11 mmol / L, and 2.9 mmol / L, respectively). The mixture was stirred at room temperature and a stirring speed of 450 r / min for 2 h to obtain a high-nickel ternary positive electrode material mixed metal ion dispersion.

[0118] (2) In 20 mL of the mixed metal ion dispersion of the high-nickel ternary cathode material obtained in step (1), 8 mL of 0.0235 mol / L oxalic acid anhydrous ethanol solution was slowly added dropwise at a rate of 2 mL / min. The mixture was stirred at room temperature and a stirring speed of 450 r / min for 5 h. The mixture was then placed in an 85°C water bath and heated and stirred at a stirring speed of 400 r / min until evaporated to dryness. The mixture was ground at a speed of 180 r / min for 8 min to obtain a lithium nickel manganese oxide precursor-coated high-nickel ternary cathode material.

[0119] (3) The lithium nickel manganese oxide precursor obtained in step (2) is coated with a high nickel ternary positive electrode material, placed in a tube furnace, and heated to 420 ° C at a rate of 5 ° C / min in a high-purity oxygen atmosphere. After sintering for 2.5 h, it is heated to 620 ° C at a rate of 5 ° C / min, sintered for 4.5 h, and cooled to room temperature to obtain lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material.

[0120] Battery assembly: Same as Example 1.

[0121] like Figure 9 As shown, the embodiment of the present invention is lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The battery assembled with O2 positive electrode material has an initial discharge capacity of up to 220.65 mAh / g at a charge and discharge voltage of 2.7 to 4.5 V and a current density of 0.1 C (20 mA / g, first 3 cycles). At a current density of 1 C (200 mA / g, starting from the 4th cycle), the initial discharge capacity is 194.84 mAh / g. After 200 cycles, the discharge capacity can still reach 158.65 mAh / g, and the capacity retention rate can reach 81.43%, indicating that the lithium nickel manganese oxide coated LiNi in the embodiment of the present invention is effective. 0.83 Co 0.11 Mn 0.06 The O2 cathode material has good cycle stability.

[0122] Comparative Example 1

[0123] This comparative example is the high nickel LiNi obtained in Reference Example 1 0.83 Co 0.11 Mn 0.06 O2 positive electrode material.

[0124] Battery assembly: Same as Example 1.

[0125] like Figure 10 As shown, the high nickel LiNi 0.83 Co 0.11Mn 0.06 The battery assembled with O2 positive electrode material has an initial discharge capacity of 218.6 mAh / g at a charge and discharge voltage of 2.7-4.5 V and a current density of 0.1 C (20 mA / g, first 3 cycles). At a current density of 1 C (200 mA / g, starting from the 4th cycle), the initial discharge capacity is 197.7 mAh / g. However, after 200 cycles, the discharge capacity is only 108.1 mAh / g, and the capacity retention rate is only 54.68%, indicating that the high nickel LiNi 0.83 Co 0.11 Mn 0.06 The cycling stability of O2 positive electrode material is poor before it is coated with lithium nickel manganese oxide.

[0126] Comparative Example 2

[0127] (1) Add 0.2488 g (1 mmol) of nickel acetate tetrahydrate, 0.7353 g (3 mmol) of manganese acetate tetrahydrate, and 0.1386 g (2.1 mmol) of lithium acetate to 50 mL of anhydrous ethanol. Stir and dissolve at room temperature and a stirring speed of 400 r / min for 4 h to obtain an anhydrous ethanol solution containing nickel, manganese, and lithium.

[0128] (2) Slowly add 15 mL of 0.4 mol / L oxalic acid solution to 50 mL of the anhydrous ethanol solution containing nickel, manganese and lithium obtained in step 1) at a rate of 2 mL / min. Stir the mixture at room temperature and a stirring speed of 400 r / min for 4 h. Place the mixture in an 80 °C water bath and heat and stir at a stirring speed of 500 r / min until it is evaporated to dryness. Move the mixture to a 120 °C oven and dry it for 6 h. Then, grind it at a speed of 200 r / min for 0.1 h to obtain a lithium nickel manganese oxide precursor.

[0129] (3) 1.0 g of high nickel LiNi obtained in Reference Example 1 was added 0.83 Co 0.11 Mn 0.06 The O2 positive electrode material and 0.01g of the lithium nickel manganese oxide precursor obtained in step (2) were placed in a ball mill, ball milled for 6 h, and then placed in a tube furnace. In a high-purity oxygen atmosphere, the temperature was first raised to 450 °C at a rate of 5 °C / min, sintered for 2 h, and then raised to 600 °C at a rate of 5 °C / min, sintered for 5 h, and cooled to room temperature to obtain lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode material.

[0130] Battery assembly: Same as Example 1.

[0131] After testing, the comparative example of the present invention, lithium nickel manganese oxide coated LiNi0.83 Co 0.11 Mn 0.06 The battery assembled with O2 positive electrode material has a discharge capacity of 188.7 mAh / g, 156.4 mAh / g and 141.1 mAh / g at 0.2 C (40 mAh / g), 5 C and 10 C high rate conditions, respectively, indicating that the comparative example of the present invention, lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The O2 positive electrode material has severe impact during the ball milling process, resulting in particle rupture, poor contact between particles, increased interface impedance, reduced lithium ion transmission rate, and affected the capacity. When the current density gradually decreases from 10 C rate and cycles back to 0.2 C rate, the discharge capacity is only 180.2 mAh / g, indicating that the comparative example of the present invention, lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 O2 positive electrode materials have poor structural stability during the charge and discharge process, low capacity under high rate conditions, relatively poor reversibility of charge and discharge reactions, and poor rate performance.

[0132] like Figure 11 As shown, in this comparative example, lithium nickel manganese oxide coated LiNi 0.83 Co 0.11 Mn 0.06 The battery assembled with O2 positive electrode material has an initial discharge capacity of 193.72 mAh / g at a charge and discharge voltage of 2.7-4.5 V and a current density of 0.1C (20 mA / g, first 3 cycles). At a current density of 1 C (200 mA / g, starting from the 4th cycle), the initial discharge capacity is 172.98 mAh / g. However, after 200 cycles, the discharge capacity is only 118.03 mAh / g, and the capacity retention rate is only 68.23%, indicating that the lithium nickel manganese oxide coated LiNi in this comparative example is not good. 0.83 Co 0.11 Mn 0.06 Compared with the oxalate co-precipitation coating method, the O2 positive electrode material has a low discharge capacity and poor cycle stability, which cannot meet the requirements for long cycle life and high energy density.

Claims

1. A method for preparing a lithium nickel manganese oxide coated high nickel ternary positive electrode material, characterized in that: The following steps are involved: (1) adding a high nickel ternary cathode material to an organic solution containing nickel, manganese and lithium, stirring and mixing, and obtaining a high nickel ternary cathode material mixed metal ion dispersion; (2) slowly adding a precipitant organic solution to the high-nickel ternary positive electrode material mixed metal ion dispersion obtained in step (1), stirring for reaction, heating and stirring until evaporated to dryness, and grinding to obtain a lithium nickel manganese oxide precursor coated high-nickel ternary positive electrode material; the molar ratio of the precipitant in the precipitant organic solution to the nickel in the high-nickel ternary positive electrode material mixed metal ion dispersion is 4 to 8:1; the concentration of the precipitant organic solution is 0.008 to 0.070 mol / L; the precipitant includes one or more of oxalic acid, carbonate or hydroxide; (3) coating the lithium nickel manganese oxide precursor obtained in step (2) with a high nickel ternary positive electrode material, sintering in an oxidizing atmosphere, and cooling to room temperature to obtain a lithium nickel manganese oxide-coated high nickel ternary positive electrode material; The lithium nickel manganese oxide coated high nickel ternary positive electrode material is a spherical particle formed by coating a high nickel ternary positive electrode material with a spinel type lithium nickel manganese oxide coating layer at a mass ratio of 0.005 to 0.040:1; the chemical formula of the high nickel ternary positive electrode material is LiNi x Co y Mn (1-x-y) O2, where 0.75≤x≤0.90, 0.05≤y≤0.15, 1-xy>0.

2. The method for preparing the lithium nickel manganese oxide coated high nickel ternary positive electrode material according to claim 1, characterized in that: The high-nickel ternary positive electrode material is an α-NaFeO2 layered structure; the average particle size of the lithium nickel manganese oxide coated high-nickel ternary positive electrode material is 10 to 20 μm; and the average thickness of the spinel lithium nickel manganese oxide coating layer is 2 to 6 nm.

3. The method for preparing the lithium nickel manganese oxide coated high nickel ternary positive electrode material according to claim 1 or 2, characterized in that: In step (1), the mass volume ratio of the high-nickel ternary positive electrode material to the organic solution containing nickel, manganese and lithium is 0.2-0.5:10 in g / mL; the average particle size of the high-nickel ternary positive electrode material is 10-20 μm; the total molar concentration of nickel, manganese and lithium ions in the organic solution containing nickel, manganese and lithium is 5-15 mmol / L; the molar ratio of nickel, manganese and lithium ions in the organic solution containing nickel, manganese and lithium is 1:2.8-3.2:1.8-2.2; the stirring and mixing temperature is room temperature, the stirring speed is 300-600 r / min, and the time is 1-3 h.

4. The method for preparing the lithium nickel manganese oxide coated high nickel ternary positive electrode material according to claim 1 or 2, characterized in that: In step (1), the preparation method of the high nickel ternary positive electrode material is as follows: grind and mix the nickel cobalt manganese hydroxide precursor and the lithium source, sinter them in an oxidizing atmosphere, and cool them to room temperature; the nickel cobalt manganese hydroxide precursor is prepared by coprecipitation method, and its chemical formula is Ni x Co y Mn (1-x-y) (OH)2, wherein 0.75≤x≤0.90, 0.05≤y≤0.15, and 1-xy>0; the average particle size of the nickel cobalt manganese hydroxide precursor is 10-20 μm; the molar ratio of the total molar number of Ni, Co, and Mn in the nickel cobalt manganese hydroxide precursor to the Li in the lithium source is 1:1.02-1.10; the lithium source includes LiOH·H2O and / or Li2CO3; the grinding speed is 100-300 r / min, and the time is 15-45 min; the oxidizing atmosphere includes an oxygen atmosphere and / or an air atmosphere; the sintering is a two-stage temperature rising sintering, first heating to 350-550°C at a rate of 1-10°C / min, sintering for 2-8h, and then heating to 550-850°C at a rate of 1-10°C / min, and sintering for 8-20h.

5. The method for preparing the lithium nickel manganese oxide coated high nickel ternary positive electrode material according to claim 3, characterized in that: In step (1), the preparation method of the high nickel ternary positive electrode material is as follows: grind and mix the nickel cobalt manganese hydroxide precursor and the lithium source, sinter them in an oxidizing atmosphere, and cool them to room temperature; the nickel cobalt manganese hydroxide precursor is prepared by coprecipitation method, and its chemical formula is Ni x Co y Mn (1-x-y) (OH)2, wherein 0.75≤x≤0.90, 0.05≤y≤0.15, and 1-xy>0; the average particle size of the nickel cobalt manganese hydroxide precursor is 10-20 μm; the molar ratio of the total molar number of Ni, Co, and Mn in the nickel cobalt manganese hydroxide precursor to the Li in the lithium source is 1:1.02-1.10; the lithium source includes LiOH·H2O and / or Li2CO3; the grinding speed is 100-300 r / min, and the time is 15-45 min; the oxidizing atmosphere includes an oxygen atmosphere and / or an air atmosphere; the sintering is a two-stage temperature rising sintering, first heating to 350-550°C at a rate of 1-10°C / min, sintering for 2-8h, and then heating to 550-850°C at a rate of 1-10°C / min, and sintering for 8-20h.

6. The method for preparing the lithium nickel manganese oxide coated high nickel ternary positive electrode material according to claim 1 or 2, characterized in that: In step (1), the preparation method of the organic solution containing nickel, manganese and lithium is as follows: adding a nickel source, a manganese source and a lithium source to an organic solvent, stirring and dissolving; the total molar concentration of the nickel element in the nickel source, the manganese element in the manganese source and the lithium element in the lithium source in the organic solution containing nickel, manganese and lithium is 5 to 15 mmol / L; the molar ratio of the nickel element in the nickel source, the manganese element in the manganese source and the lithium element in the lithium source is 1:2.8 to 3.2:1.8 to 2.2; the temperature of the stirring and dissolving is room temperature, the stirring speed is 300 to 600 r / min, and the time is 2 to 6 h; the lithium source includes one or more of lithium acetate, lithium nitrate or lithium sulfate, and their hydrates; the nickel source includes nickel acetate, nickel nitrate or nickel sulfate, and their hydrates; the manganese source includes manganese acetate, manganese nitrate or manganese sulfate, and their hydrates; the organic solvent includes one or more of anhydrous ethanol, methanol or isopropanol.

7. The method for preparing the lithium nickel manganese oxide coated high nickel ternary positive electrode material according to claim 3, characterized in that: In step (1), the preparation method of the organic solution containing nickel, manganese and lithium is as follows: adding a nickel source, a manganese source and a lithium source to an organic solvent, stirring and dissolving; the total molar concentration of the nickel element in the nickel source, the manganese element in the manganese source and the lithium element in the lithium source in the organic solution containing nickel, manganese and lithium is 5 to 15 mmol / L; the molar ratio of the nickel element in the nickel source, the manganese element in the manganese source and the lithium element in the lithium source is 1:2.8 to 3.2:1.8 to 2.2; the temperature of the stirring and dissolving is room temperature, the stirring speed is 300 to 600 r / min, and the time is 2 to 6 h; the lithium source includes one or more of lithium acetate, lithium nitrate or lithium sulfate, and their hydrates; the nickel source includes nickel acetate, nickel nitrate or nickel sulfate, and their hydrates; the manganese source includes manganese acetate, manganese nitrate or manganese sulfate, and their hydrates; the organic solvent includes one or more of anhydrous ethanol, methanol or isopropanol.

8. The method for preparing the lithium nickel manganese oxide coated high nickel ternary positive electrode material according to claim 4, characterized in that: In step (1), the preparation method of the organic solution containing nickel, manganese and lithium is as follows: adding a nickel source, a manganese source and a lithium source to an organic solvent, stirring and dissolving; the total molar concentration of the nickel element in the nickel source, the manganese element in the manganese source and the lithium element in the lithium source in the organic solution containing nickel, manganese and lithium is 5 to 15 mmol / L; the molar ratio of the nickel element in the nickel source, the manganese element in the manganese source and the lithium element in the lithium source is 1:2.8 to 3.2:1.8 to 2.2; the temperature of the stirring and dissolving is room temperature, the stirring speed is 300 to 600 r / min, and the time is 2 to 6 h; the lithium source includes one or more of lithium acetate, lithium nitrate or lithium sulfate, and their hydrates; the nickel source includes nickel acetate, nickel nitrate or nickel sulfate, and their hydrates; the manganese source includes manganese acetate, manganese nitrate or manganese sulfate, and their hydrates; the organic solvent includes one or more of anhydrous ethanol, methanol or isopropanol.

9. The method for preparing the lithium nickel manganese oxide coated high nickel ternary positive electrode material according to claim 1 or 2, characterized in that: In step (2), the solvent in the precipitant organic solution includes one or more of anhydrous ethanol, acetone or isopropanol; the speed of the slow dripping is 1 to 10 mL / min; the temperature of the stirring reaction is room temperature, the stirring speed is 300 to 600 r / min, and the time is 2 to 6 h; the heating and stirring until evaporated refers to: heating and stirring until evaporated in a 70 to 100 ° C water bath at a stirring speed of 300 to 600 r / min; the grinding speed is 100 to 300 r / min, and the time is 3 to 12 min.

10. The method for preparing the high-nickel ternary positive electrode material coated with lithium nickel manganese oxide according to claim 3, characterized in that: In step (2), the solvent in the precipitant organic solution includes one or more of anhydrous ethanol, acetone or isopropanol; the speed of the slow dripping is 1 to 10 mL / min; the temperature of the stirring reaction is room temperature, the stirring speed is 300 to 600 r / min, and the time is 2 to 6 h; the heating and stirring until evaporated refers to: heating and stirring until evaporated in a water bath at 70 to 100 ° C at a stirring speed of 300 to 600 r / min; the grinding speed is 100 to 300 r / min, and the time is 3 to 12 min.

11. The method for preparing the lithium nickel manganese oxide coated high nickel ternary positive electrode material according to claim 4, characterized in that: In step (2), the solvent in the precipitant organic solution includes one or more of anhydrous ethanol, acetone or isopropanol; the speed of the slow dripping is 1 to 10 mL / min; the temperature of the stirring reaction is room temperature, the stirring speed is 300 to 600 r / min, and the time is 2 to 6 h; the heating and stirring until evaporated refers to: heating and stirring until evaporated in a water bath at 70 to 100 ° C at a stirring speed of 300 to 600 r / min; the grinding speed is 100 to 300 r / min, and the time is 3 to 12 min.

12. The method for preparing the high-nickel ternary positive electrode material coated with lithium nickel manganese oxide according to claim 6, characterized in that: In step (2), the solvent in the precipitant organic solution includes one or more of anhydrous ethanol, acetone or isopropanol; the speed of the slow dripping is 1 to 10 mL / min; the temperature of the stirring reaction is room temperature, the stirring speed is 300 to 600 r / min, and the time is 2 to 6 h; the heating and stirring until evaporated refers to: heating and stirring until evaporated in a water bath at 70 to 100 ° C at a stirring speed of 300 to 600 r / min; the grinding speed is 100 to 300 r / min, and the time is 3 to 12 min.

13. The method for preparing the lithium nickel manganese oxide coated high nickel ternary positive electrode material according to claim 1 or 2, characterized in that: In step (3), the oxidizing atmosphere includes an oxygen atmosphere and / or an air atmosphere; the sintering is a two-stage temperature-raising sintering, firstly heating the temperature to 300-550°C at a rate of 2-8°C / min, sintering for 1-4 hours, and then heating the temperature to 500-700°C at a rate of 2-8°C / min, and sintering for 2-8 hours.

14. The method for preparing the high-nickel ternary positive electrode material coated with lithium nickel manganese oxide according to claim 3, characterized in that: In step (3), the oxidizing atmosphere includes an oxygen atmosphere and / or an air atmosphere; the sintering is a two-stage temperature-raising sintering, firstly heating the temperature to 300-550°C at a rate of 2-8°C / min, sintering for 1-4 hours, and then heating the temperature to 500-700°C at a rate of 2-8°C / min, and sintering for 2-8 hours.

15. The method for preparing the lithium nickel manganese oxide coated high nickel ternary positive electrode material according to claim 4, characterized in that: In step (3), the oxidizing atmosphere includes an oxygen atmosphere and / or an air atmosphere; the sintering is a two-stage temperature-raising sintering, firstly heating the temperature to 300-550°C at a rate of 2-8°C / min, sintering for 1-4 hours, and then heating the temperature to 500-700°C at a rate of 2-8°C / min, and sintering for 2-8 hours.

16. The method for preparing the lithium nickel manganese oxide coated high nickel ternary positive electrode material according to claim 6, characterized in that: In step (3), the oxidizing atmosphere includes an oxygen atmosphere and / or an air atmosphere; the sintering is a two-stage temperature-raising sintering, firstly heating the temperature to 300-550°C at a rate of 2-8°C / min, sintering for 1-4 hours, and then heating the temperature to 500-700°C at a rate of 2-8°C / min, and sintering for 2-8 hours.

17. The method for preparing the high-nickel ternary positive electrode material coated with lithium nickel manganese oxide according to claim 9, characterized in that: In step (3), the oxidizing atmosphere includes an oxygen atmosphere and / or an air atmosphere; the sintering is a two-stage temperature-raising sintering, firstly heating the temperature to 300-550°C at a rate of 2-8°C / min, sintering for 1-4 hours, and then heating the temperature to 500-700°C at a rate of 2-8°C / min, and sintering for 2-8 hours.

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