Lanthanide perovskite oxide coated high nickel ternary positive electrode material and preparation method

Abstract

Lanthanum perovskite oxide coated high nickel ternary positive electrode material and preparation method thereof, wherein the positive electrode material is a spherical particle formed by coating a high nickel ternary positive electrode material with a lanthanum perovskite oxide coating layer at a mass ratio of 0.01 to 0.03:1; the chemical formula of the lanthanum perovskite oxide is La z Ca 1‑z CoO3, where 0 < z ≤ 1; the chemical formula of the high nickel ternary cathode material is LiNi x Co y Mn (1‑x‑y) O2, wherein 0.80≤x≤0.96, 0.01≤y≤0.10, and 1-x-y>0. The preparation method comprises ball-milling a lanthanide perovskite oxide with a high-nickel ternary cathode material, followed by low-temperature sintering under a protective atmosphere. The cathode material of the present invention exhibits high lithium ion and electron conductivity during charge and discharge, is highly reversible, has a stable structure, and exhibits excellent rate capability and cycle stability. The method of the present invention is simple, low-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 lanthanide perovskite-type oxide-coated high-nickel ternary positive electrode material and a preparation method thereof. Background Art

[0002] High-nickel ternary cathode materials are one of the most promising cathode materials for lithium-ion power batteries in the future due to their low cost and high energy density. However, the biggest drawback of high-nickel ternary materials is their poor structural and interface stability. Their surface particles are prone to phase transitions from layered structure to spinel structure to inactive rock salt phase. This prominent interface problem leads to structural instability, resulting in rapid and significant degradation of lithium storage capacity and cycling performance, which will seriously restrict the development of their large-scale application. Therefore, improving the structural stability of high-nickel cathode materials through modification methods such as interface modification is crucial for developing cathode materials with advantages such as low cost, high performance, and high capacity.

[0003] CN114864914A discloses a lithium niobate-coated modified high-nickel ternary cathode material for lithium-ion batteries and a preparation method thereof. The method comprises adding an organic acid, a niobium source, and a lithium source to a dispersion containing the high-nickel ternary cathode material, stirring to evaporate the solvent, and then calcining to obtain the lithium niobate-coated high-nickel ternary cathode material. While this method is simple, energy-efficient, and capable of large-scale production of high-performance lithium-ion battery cathode materials, in actual operation, the high-nickel ternary material is exposed to a liquid phase environment for a long time, which significantly affects its structure and is difficult to implement in industrial production.

[0004] CN116177624A discloses a spinel structure coating modified lithium-ion battery high-nickel ternary cathode material and preparation method. The method comprises preparing a nickel-cobalt-manganese precursor with a manganese-rich surface by coprecipitation reaction, then thoroughly mixing the nickel-cobalt-manganese precursor with a lithium salt, and calcining the mixture under an oxygen atmosphere according to a three-stage programmed temperature-controlled heating method to obtain a high-nickel ternary cathode material with a spinel structure coating. Although this method has a simple preparation process, a low reaction temperature, and can significantly improve the cyclic stability of the material, the control conditions are relatively strict during actual operation, and the Mn content on the material surface is difficult to accurately control, which generally makes it difficult to widely promote and use in industrial production.

[0005] 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 solution, then adding the high-nickel ternary cathode material and the phosphorus source solution, heating, and drying the solution to obtain a powdered material. The powdered material is then calcined to obtain the calcium phosphate-coated high-nickel ternary cathode material. Although coating the surface of the high-nickel ternary cathode material with calcium phosphate and then sintering it 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 is not 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.

[0006] CN114853089A discloses a method for preparing a magnesium borate-coated high-nickel ternary cathode material. The method comprises: uniformly mixing a lithium source and a ternary precursor, sintering the mixture at high temperature in an oxygen atmosphere, cooling the mixture to room temperature, crushing and sieving the mixture to obtain a primary sintered material powder; uniformly mixing the sintered material powder with magnesium borate, coating and sintering the mixture at high temperature, and cooling the mixture to room temperature to obtain a magnesium borate-coated high-nickel ternary cathode material. Although this method can significantly reduce the residual alkali content, lower the powder resistance of the material, and improve the material's cycle and rate performance, the cost may limit the competitiveness of the magnesium borate-coated high-nickel ternary cathode material in low-cost, large-scale applications.

[0007] CN109256557A discloses a perovskite-type oxide-coated high-nickel layered oxide lithium battery positive electrode material and its preparation method, which comprises dissolving a nickel source, a cobalt source, and a manganese source to obtain a mixed metal salt solution, adding an inorganic strong base and an ammonia solution to adjust the pH, reacting by stirring, filtering, washing, and drying to obtain a high-nickel ternary precursor material; then mixing and calcining with a lithium source, and then mixing and calcining with a lanthanum source and an aluminum source, and grinding to obtain a perovskite-type oxide-coated high-nickel modified high-nickel ternary layered positive electrode material. Although the preparation method of this method is simple, the rate performance and cycle performance of the prepared material are relatively excellent, and good cycle stability can still be maintained under high temperature and high pressure test conditions, directly generating the perovskite material by solid-phase reaction and coating it will have problems such as large product particles, wide particle size distribution range, and poor product consistency caused by uneven reaction.

[0008] In summary, it is urgent to find a lanthanide perovskite oxide-coated high-nickel ternary positive electrode material with high lithium ion and electron conductivity, highly reversible charge and discharge reactions, stable thermodynamic structure, high safety, good rate performance and cycle stability during the charge and discharge process, as well as a preparation method for lanthanide perovskite 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 lanthanide perovskite oxide-coated high-nickel ternary positive electrode material with high lithium ion and electron conductivity, highly reversible charge and discharge reactions, stable thermodynamic structure, high safety, good rate performance and cycle stability during the charge and discharge process.

[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 lanthanide perovskite-type 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 lanthanide perovskite oxide coated high nickel ternary positive electrode material, wherein the lanthanide perovskite oxide coated high nickel ternary positive electrode material is a spherical particle formed by coating the high nickel ternary positive electrode material with a lanthanide perovskite oxide coating layer at a mass ratio of 0.01 to 0.03:1; the chemical formula of the lanthanide perovskite oxide is La z Ca 1-z CoO3, wherein 0.5≤z≤1.0; the chemical formula of the high nickel ternary positive electrode material is LiNi x Co y Mn (1-x-y) O2, wherein 0.80≤x≤0.96 (more preferably 0.90≤x≤0.96), 0.01≤y≤0.10 (more preferably 0.01≤y≤0.03), and 1-xy>0. La z Ca 1-z As a typical oxygen ion conductor, CoO3 has the advantages of low price, high oxygen mobility, and good structural stability. At the same time, it can stabilize oxygen vacancies / interstices and inhibit the reactivity of surface lattice oxygen ions. After coating the positive electrode material, it can effectively inhibit the release of lattice oxygen, irreversible phase transition, and the generation of intercrystalline microcracks, thereby significantly improving the structural and interfacial stability of the material and effectively improving its electrochemical performance. The present invention creatively proposes a lanthanide perovskite oxide La z Ca 1-z CoO3 coated high nickel ternary cathode material enables it to give full play to the advantages of good structural stability of perovskite oxide and the ability to inhibit the reactivity of surface lattice oxygen ions during the cycle. z Ca 1-z After the CoO3 coating, the high nickel ternary cathode material improves the cycle stability during the charge and discharge cycle, and also ensures the rapid deintercalation reaction of the layered high nickel ternary cathode material; z Ca 1-zThe CoO3 coating material can improve the interface stability and structural stability of the material, effectively inhibit the corrosion of the electrolyte, phase change and release of lattice oxygen, reduce the dissolution of transition metals in the active material, reduce the occurrence of side reactions and gas generation during electrode polarization and cycling, thereby significantly improving the cycle performance, rate performance, reversible capacity and first coulombic efficiency of the high-nickel ternary positive electrode material, and showing excellent electrochemical performance. ABO3 type perovskite oxide has the advantages of low price, good redox performance, high oxygen mobility and good thermal stability. Among them, lanthanum has high thermal stability, which can ensure that the perovskite material still has excellent stability under extreme working conditions. Therefore, La is determined to be the A-site element; Ca 2+ and La 3+ The ionic radius of Ca 2+ Substitution at the La position can further enhance the structural stability of perovskite materials, and due to its wide availability, low price, and relatively weak Ca-O bond strength, it is considered a promising A-site dopant. Co was identified as a B-site element based on its advantages in ternary cathode materials, such as its ability to stabilize the layered structure of the material and reduce cation mixing, which is beneficial to battery cycle performance.

[0012] Preferably, the high-nickel ternary positive electrode material has a typical layered structure, and the three elements Ni, Co, and Mn are evenly distributed in the high-nickel ternary positive electrode material.

[0013] Preferably, the average particle size of the lanthanide perovskite oxide-coated high-nickel ternary cathode material is 2 to 8 μm. When the secondary particles of the lanthanide perovskite oxide-coated high-nickel ternary cathode material are within this particle size, rapid lithium ion diffusion dynamics within the particles can be ensured, while preventing material agglomeration during storage, which could deteriorate electrochemical performance.

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

[0015] The technical solution adopted by the present invention to further solve its technical problems is as follows: a preparation method of a lanthanide perovskite oxide-coated high-nickel ternary positive electrode material, comprising ball-milling the lanthanide perovskite oxide and the high-nickel ternary positive electrode material, and sintering them at a low temperature under a protective atmosphere.

[0016] The invention idea of ​​the method of the present invention is to obtain a lanthanide perovskite oxide La with a conductive network structure by ball milling and low temperature solid phase sintering under a protective atmosphere. z Ca 1-zCoO3-coated high-nickel ternary cathode material. Due to the extremely high nickel content of the original material, liquid-phase coating easily causes the material to absorb moisture, leading to an increase in residual alkali on the surface. Therefore, solid-phase coating is used. Through the diffusion, chemical reaction, and mutual dissolution of substances at the solid-phase interface, the coating layer is formed and strengthened, thereby improving the stability of the material.

[0017] Preferably, the mass ratio of the lanthanide perovskite oxide to the high-nickel ternary cathode material is 0.01 to 0.03:1. Excessively high coating levels may increase the diffusion paths of electrons and lithium ions, reducing the electrochemical reaction rate and ion transport rate of the active material, leading to a decrease in the electrochemical performance of the cathode material. Conversely, excessively low coating levels can result in the active material remaining exposed to the electrolyte, easily damaging the solid electrolyte interface (SEI) layer and corroding the electrode material, resulting in a decrease in battery safety and cycle life. Within this coating range, the electrochemical performance of the material can be optimized to the greatest extent possible.

[0018] Preferably, the ball milling mixing speed is 100-300 r / min (more preferably 150-200 r / min) for 2-10 hours (more preferably 4-8 hours). Selecting a lower speed can avoid the breakage of secondary particles due to violent collisions between the ball milling beads and the secondary particles, which can cause the collapse and disintegration of the layered positive electrode material structure and deteriorate the electrochemical performance. In addition, solid-phase coating requires an appropriate ball milling time. The ball milling time should not be too long or too short. Excessive ball milling time can cause cracks or damage on the surface of the positive electrode material particles, making it difficult for the coating material to fully cover the particle surface, reducing the coating effect. On the other hand, too short a ball milling time will result in high particle surface roughness, which prevents the coating material from fully covering the particle surface, also affecting the coating effect.

[0019] Preferably, the protective atmosphere includes argon and / or nitrogen.

[0020] Preferably, the low-temperature sintering is performed by increasing the temperature to 300-550°C (more preferably 450-550°C) at a rate of 1-10°C / min (more preferably 2-8°C / min) and sintering for 2-10 hours (more preferably 4-8 hours). Low-temperature sintering helps to better bond the coating layer to the base material, thereby improving the mechanical properties and stability of the material. The sintering temperature range does not exceed the thermal stability range of the base material, thus not damaging the structural stability of the base material and falling within a reasonable low-temperature sintering range. Furthermore, the low-temperature sintering process requires sufficient reaction time, but excessively long reaction times increase energy consumption and result in unnecessary waste of resources.

[0021] Preferably, the method for preparing the lanthanide perovskite-type oxide comprises the following steps:

[0022] 1) adding a lanthanum source, a calcium source, and a cobalt source into a solvent, and ultrasonically dispersing them to obtain a metal ion mixed solution; adding a complexing agent into the solvent, and ultrasonically dispersing them to obtain a complexing agent solution;

[0023] 2) adding the complexing agent solution obtained in step 1) dropwise to the metal ion mixed solution obtained in step 1), or adding the metal ion mixed solution obtained in step 1) dropwise to the complexing agent solution obtained in step 1), performing a stirring reaction, heating, performing a second stirring reaction, drying, ball milling, sintering in an oxidizing atmosphere, and cooling to room temperature to obtain a lanthanide perovskite-type oxide.

[0024] Preferably, in step 1), the molar ratio of lanthanum in the lanthanum source, calcium in the calcium source, and cobalt in the cobalt source is 0.5-1.0:0-0.5:1. Lanthanum is a designated A-site element to ensure the coating material has strong stability, and its A-site content must be ≥50%. Calcium is an A-site doping element that helps stabilize the material structure, and its A-site content must be ≤50%. Cobalt is a designated B-site element, and its B-site content is 100% without considering B-site doping.

[0025] Preferably, in step 1), the total molar concentration of the metal ions in the mixed metal ion solution is 0.1 to 0.9 mol / L (more preferably 0.2 to 0.7 mol / L). The molar concentration of the metal ions affects the crystal structure of the product. Lower concentrations may result in the formation of amorphous or small crystals, while higher concentrations may lead to the formation of larger crystals or multiple phases. Within this concentration range, the solvation, hydrolysis, and polycondensation reactions proceed normally, ensuring that the product has a complete crystalline form and a uniform particle size distribution.

[0026] Preferably, in step 1), the lanthanum source includes one or more of lanthanum nitrate, lanthanum acetate or lanthanum chloride, and hydrates thereof.

[0027] Preferably, in step 1), the calcium source includes one or more of calcium nitrate, calcium acetate or calcium chloride, and hydrates thereof.

[0028] Preferably, in step 1), the cobalt source includes one or more of cobalt nitrate, cobalt acetate or cobalt chloride, and hydrates thereof.

[0029] Preferably, in step 1), the concentration of the complexing agent solution is 0.1 to 0.8 mol / L (more preferably 0.12 to 0.50 mol / L). A complexing agent solution of appropriate concentration can effectively stabilize metal ions, preventing their aggregation or precipitation. Lower complexing agent concentrations may not fully complex metal ions, and the concentration of the complexing agent can also affect the rate of the gelation process. An ideal complexing agent concentration promotes intermolecular cross-linking and rapid gel formation. This concentration range ensures the normal progress of the gelation reaction and is conducive to the synthesis of a gel product with uniform morphology and particle size distribution.

[0030] Preferably, in step 1), the complexing agent includes one or more of citric acid, ethylenediaminetetraacetic acid or ethylene glycol.

[0031] Preferably, in step 1), the solvent is a mixed solvent of anhydrous ethanol and deionized water in a volume ratio of 1:1 to 3. As polar solvents, both water and ethanol can effectively dissolve metal salts, thereby forming a uniform sol. Ethanol helps regulate the reaction rate and promotes polymerization, forming a more stable polymer network, while water, with its strong hydrophilicity, contributes to a more uniform sol. Therefore, the mixed use of the two solvents can improve the output efficiency of the sol-gel method and the properties of the final material.

[0032] Preferably, in step 1), the frequency of the ultrasonic dispersion is 30 to 60 kHz, and the time is 1 to 4 hours.

[0033] Preferably, in step 2), the volume ratio of the complexing agent solution to the metal ion mixed solution is 1:0.4 to 4.0 (more preferably 1:0.6 to 2.6). When the lanthanum source, calcium source, and cobalt source are easily precipitated solutes such as acetate, the metal ion mixed solution is added dropwise to the complexing agent solution to avoid the formation of precipitated impurities.

[0034] Preferably, in step 2), the molar ratio of the complexing agent in the complexing agent solution to the cobalt ions in the metal ion mixed solution is 1.0 to 1.5:1.

[0035] An appropriate volume ratio of the complexing agent solution to the metal ion mixed solution, as well as the molar ratio of the complexing agent to the cobalt ion can improve the crystallinity of the material, make the particles more uniform, and have a more complete morphology. If the ratio is too large or too small, it may lead to a decrease in the crystallinity of the material, uneven particle size, and even the formation of disordered particle aggregates.

[0036] Preferably, in step 2), the addition rate is 60-120 mL / h. The complexing agent's addition rate can affect the reaction process. If the addition rate is too fast, the reaction may accelerate, leading to rapid aggregation of metal ions and uneven phase separation or precipitation. Therefore, the complexing agent should be added slowly to allow the reaction to proceed over a longer period of time. This ensures uniform dispersion of the metal ions and maintains good uniformity throughout the reaction system, resulting in a more uniform and stable gel structure.

[0037] Preferably, in step 2), during the dropwise addition, the added metal ion mixed solution or complexing agent solution is stirred at a stirring speed of 100 to 600 r / min.

[0038] Preferably, in step 2), the primary stirring reaction is carried out at a temperature of 20-30°C, at a stirring speed of 100-600 rpm, and for 10-20 hours. The primary stirring reaction is preferably temperature-controlled in a water bath. Using a lanthanum source, a calcium source, and a cobalt source as raw materials in a solvent containing a complexing agent, a single stirring reaction ensures uniform complexation without precipitation.

[0039] Preferably, in step 2), the temperature is raised to 30-80°C.

[0040] Preferably, in step 2), the temperature of the secondary stirring reaction is 30-80°C, the stirring speed is 100-600 r / min, and the time is 8-14 hours. During the secondary stirring process, the complex product undergoes a sol-gel reaction to synthesize a precursor of a lanthanide perovskite oxide with a complete crystal structure. Because the sol-gel method can ensure strict control of the stoichiometric ratio, the resulting product has high purity, small particle size, and uniform distribution. The gel contains a large amount of liquid phase or pores, which makes it difficult for particles to agglomerate during the heat treatment process, thus avoiding the problems of uneven particle size, incomplete reaction, and particle agglomeration in the synthesis of materials synthesized by pure solid-phase reactions.

[0041] Preferably, in step 2), the drying is vacuum drying.

[0042] Preferably, the vacuum drying temperature is 80 to 120° C., the vacuum degree is -0.06 to -0.09 MPa, and the time is 6 to 12 h.

[0043] Preferably, in step 2), the ball milling speed is 300-700 r / min and the time is 2-10 h.

[0044] Preferably, in step 2), the oxidizing atmosphere includes oxygen atmosphere and / or air atmosphere.

[0045] Preferably, in step 2), the sintering is a two-stage temperature-increasing sintering process: first, the temperature is increased 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 2-10 hours (more preferably 2-6 hours), and then the temperature is increased to 600-900°C (more preferably 700-800°C) at a rate of 1-10°C / min (more preferably 3-6°C / min) and sintered for 9-16 hours (more preferably 12-15 hours). High-temperature sintering promotes the formation of the perovskite phase, which is crucial for preparing materials with stable crystal structures. Furthermore, high-temperature sintering removes excess solvents, gases, and other volatile substances produced during the synthesis process, thereby improving the density and mechanical strength of the final material. The calcination time, calcination temperature, and heating rate range are optimized to maximize crystallization, increase density, improve microstructure, and optimize the overall performance of the material.

[0046] Preferably, 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.

[0047] Preferably, the chemical formula of the nickel cobalt manganese hydroxide precursor is Ni x Co y Mn (1-x-y) (OH)2, where 0.80≤x≤0.96, 0.01≤y≤0.10, 1-xy>0.

[0048] Preferably, the average particle size of the nickel-cobalt-manganese hydroxide precursor is 2 to 8 μm.

[0049] 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 1:1.01 to 1.08.

[0050] Preferably, the lithium source comprises LiOH·H2O and / or Li2CO3.

[0051] Preferably, the grinding speed is 100 to 300 r / min, and the grinding time is 12 to 48 min.

[0052] Preferably, the oxidizing atmosphere includes an oxygen atmosphere and / or an air atmosphere.

[0053] 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 3-7°C / min), sintered for 2-6 hours (more preferably 3-5 hours), and then raised to 550-800°C (more preferably 600-700°C) at a rate of 1-10°C / min (more preferably 3-7°C / min) and sintered for 8-14 hours (more preferably 10-13 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.

[0054] The protective atmosphere or oxygen atmosphere used in the present invention is a high-purity gas with a purity of ≥99.99%.

[0055] The beneficial effects of the present invention are as follows:

[0056] (1) The lanthanide perovskite oxide-coated high-nickel ternary cathode material of the present invention is uniformly coated, and the secondary particles are spherical in shape with an average particle size of 2 to 8 μm, inheriting 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 lanthanide perovskite oxide coating layer with a uniform average thickness of 2 to 6 nm. The three elements Ni, Co, and Mn are uniformly distributed in the high-nickel ternary cathode material;

[0057] (2) The battery assembled with the lanthanide perovskite oxide coated high nickel ternary positive electrode material of the present invention has an initial discharge capacity of 222.9 mAh / g, 201.6 mAh / g, and 192.2 mAh / g at current densities of 0.2 C (40 mAh / g), 5 C, and 10 C, respectively. This indicates that the positive electrode material can maintain good 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 4.3 V and a current density of 1 C, the initial discharge capacity can be as high as 221.4 mAh / g. After 100 cycles, the discharge capacity can be as high as 198.17 mAh / g, and the retention rate can be as high as 92.61%. This indicates that the lanthanide perovskite oxide coated high nickel ternary positive electrode material of the present invention has a stable thermodynamic structure, high safety, and good cycle stability.

[0058] (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

[0059] Figure 1 The lanthanide perovskite oxide La obtained in Reference Example 1 of the present invention 0.8 Ca 0.2 XRD pattern of CoO3;

[0060] Figure 2 The lanthanide perovskite oxide La obtained in Reference Example 1 of the present invention 0.8 Ca 0.2 SEM image of CoO3;

[0061] Figure 3 The lanthanide perovskite oxide La of Example 1 of the present invention 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 XRD pattern of O2 cathode material;

[0062] Figure 4 The lanthanide perovskite oxide La of Example 1 of the present invention 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 SEM image of O2 cathode material;

[0063] Figure 5 The lanthanide perovskite oxide La of Example 1 of the present invention 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 TEM image of O2 cathode material;

[0064] Figure 6 The lanthanide perovskite oxide La of Example 1 of the present invention 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 Rate curve of the battery assembled with O2 positive electrode material;

[0065] Figure 7 The lanthanide perovskite oxide La of Example 1 of the present invention 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03Mn 0.01 Discharge cycle curve of the battery assembled with O2 positive electrode material;

[0066] Figure 8 Example 2 of the present invention is lanthanide perovskite oxide La 0.5 Ca 0.5 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 Discharge cycle curve of the battery assembled with O2 positive electrode material;

[0067] Figure 9 Example 3 of the present invention is lanthanide perovskite oxide La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 Discharge cycle curve of the battery assembled with O2 positive electrode material;

[0068] Figure 10 The high nickel ternary LiNi 0.96 Co 0.03 Mn 0.01 Discharge cycle curve of the battery assembled with O2 positive electrode material;

[0069] Figure 11 The synthetic lanthanide perovskite oxide La used in Comparative Example 2 of the present invention is 0.8 Ca 0.2 XRD pattern of CoO3;

[0070] Figure 12 The synthetic lanthanide perovskite oxide La used in Comparative Example 2 of the present invention is 0.8 Ca 0.2 SEM image of CoO3;

[0071] Figure 13 The lanthanide perovskite oxide La is a comparative example 2 of the present invention. 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 Discharge cycle curve of the battery assembled with O2 positive electrode material;

[0072] Figure 14 The lanthanide perovskite oxide La is a comparative example 3 of the present invention. 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01Discharge cycle curve of the battery assembled with O2 positive electrode material. DETAILED DESCRIPTION

[0073] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0074] The lanthanum nitrate, cobalt nitrate, and calcium nitrate used in the Examples and Comparative Examples of the present invention were all purchased from Aladdin Reagent Co., Ltd.; the purity of the high-purity gas used was 99.99%; the raw materials or chemical reagents used in the Examples and Comparative Examples of the present invention were all obtained through conventional commercial channels unless otherwise specified.

[0075] Lanthanide perovskite oxide La 0.8 Ca 0.2 Preparation method of CoO3 Reference Example 1

[0076] 1) Add 1.5588 g (0.0036 mol) of lanthanum nitrate hexahydrate, 0.2125 g (0.0009 mol) of calcium nitrate tetrahydrate, and 1.3096 g (0.0045 mol) of cobalt nitrate hexahydrate to 30 mL of solvent (anhydrous ethanol to deionized water, volume ratio: 1:1) and ultrasonically disperse them at a frequency of 50 kHz for 2 h to obtain a metal ion mixed solution. Add 0.9456 g (0.0045 mol) of citric acid monohydrate to 20 mL of solvent (anhydrous ethanol to deionized water, volume ratio: 1:1) and ultrasonically disperse them at a frequency of 50 kHz for 2 h to obtain a 0.225 mol / L citric acid solution.

[0077] 2) 20 mL of the 0.225 mol / L citric acid solution obtained in step 1) was added dropwise at a rate of 90 mL / h to 30 mL of the metal ion mixed solution obtained in step 1) stirred at a stirring speed of 300 r / min. The mixture was stirred for 12 h at a water bath temperature of 25 ° C and a stirring speed of 300 r / min. After heating to 50 ° C, the mixture was stirred for 10 h at 50 ° C and a stirring speed of 300 r / min. After forming a gel, it was vacuum dried at 100 ° C and -0.07 MPa for 10 h. After ball milling at a speed of 600 r / min for 6 h, it was sintered in a two-stage temperature rising manner in a high-purity oxygen atmosphere. The temperature was first raised to 480 ° C at a rate of 5 ° C / min and sintered for 6 h. After that, the temperature was raised to 750 ° C at a rate of 5 ° C / min and sintered for 12 h. The lanthanide perovskite oxide La was obtained. 0.8 Ca 0.2 CoO3.

[0078] like Figure 1 As shown, the lanthanide perovskite oxide La obtained in Reference Example 1 of the present invention0.8 Ca 0.2 CoO3 and La 0.8 Ca 0.2 The characteristic peaks on the standard PDF card of CoO3 (PDF#36-1388) are consistent, and the crystal structure is complete.

[0079] like Figure 2 As shown, the lanthanide perovskite oxide La obtained in Reference Example 1 of the present invention 0.8 Ca 0.2 CoO3 is a porous network material with good conductivity, which is conducive to the transmission of lithium ions.

[0080] Lanthanide perovskite oxide La 0.5 Ca 0.5 Preparation method of CoO3 Reference Example 2

[0081] 1) Add 1.0825 g (0.0025 mol) of lanthanum nitrate hexahydrate, 0.5904 g (0.0025 mol) of calcium nitrate tetrahydrate, and 1.4552 g (0.0050 mol) of cobalt nitrate hexahydrate to 30 mL of solvent (anhydrous ethanol to deionized water, volume ratio: 1:1) and ultrasonically disperse them at a frequency of 40 kHz for 1 h to obtain a metal ion mixed solution. Add 1.0717 g (0.0051 mol) of citric acid monohydrate to 20 mL of solvent (anhydrous ethanol to deionized water, volume ratio: 1:1) and ultrasonically disperse them at a frequency of 40 kHz for 1 h to obtain a 0.255 mol / L citric acid solution.

[0082] 2) 20 mL of the 0.255 mol / L citric acid solution obtained in step 1) was added dropwise at a rate of 100 mL / h to 30 mL of the metal ion mixed solution obtained in step 1) stirred at a stirring speed of 450 r / min. The mixture was stirred for 14 h at a water bath temperature of 25 ° C and a stirring speed of 450 r / min. After heating to 60 ° C, the mixture was stirred for 9 h at 60 ° C and a stirring speed of 300 r / min. After forming a gel, it was vacuum dried at 90 ° C and -0.08 MPa for 12 h. After ball milling at a speed of 650 r / min for 6 h, it was sintered in a two-stage temperature rising manner in a high-purity oxygen atmosphere. The temperature was first raised to 480 ° C at a rate of 5 ° C / min and sintered for 6 h. After that, the temperature was raised to 750 ° C at a rate of 5 ° C / min and sintered for 12 h. The lanthanide perovskite oxide La was obtained. 0.5 Ca 0.5 CoO3.

[0083] After testing, the lanthanide perovskite oxide La obtained in Reference Example 2 of the present invention 0.5Ca 0.5 CoO3 and La 0.8 Ca 0.2 The characteristic peaks on the standard PDF card of CoO3 (PDF#36-1388) are consistent, and the crystal structure is complete.

[0084] After testing, the lanthanide perovskite oxide La obtained in Reference Example 2 of the present invention 0.5 Ca 0.5 CoO3 is a porous network material with good conductivity, which is conducive to the transmission of lithium ions.

[0085] Lanthanide perovskite oxide La 0.8 Ca 0.2 Preparation method of CoO3 Reference Example 3

[0086] 1) Add 1.2350 g (0.0036 mol) of lanthanum acetate sesquihydrate, 0.1586 g (0.0009 mol) of calcium acetate monohydrate, and 1.1209 g (0.0045 mol) of cobalt acetate tetrahydrate to 20 mL of solvent (anhydrous ethanol to deionized water, volume ratio: 1:2) and ultrasonically disperse them at 60 kHz for 3 h to obtain a metal ion mixed solution. Add 0.9456 g (0.0045 mol) of citric acid monohydrate to 30 mL of solvent (anhydrous ethanol to deionized water, volume ratio: 1:2) and ultrasonically disperse them at 60 kHz for 3 h to obtain a 0.15 mol / L citric acid solution.

[0087] 2) 20 mL of the metal ion mixed solution obtained in step 1) was added dropwise at a rate of 80 mL / h to 30 mL of 0.15 mol / L citric acid solution obtained in step 1) stirred at a stirring speed of 450 r / min. The reaction was stirred for 14 h at a water bath temperature of 25 ° C and a stirring speed of 500 r / min. After heating to 60 ° C, the reaction was stirred for 11 h at 60 ° C and a stirring speed of 500 r / min. After forming a gel, it was vacuum dried at 100 ° C and -0.09 MPa for 12 h. After ball milling at a speed of 700 r / min for 8 h, it was sintered in a two-stage temperature rising manner in a high-purity oxygen atmosphere. The temperature was first raised to 500 ° C at a rate of 6 ° C / min and sintered for 5 h. Then, the temperature was raised to 720 ° C at a rate of 6 ° C / min and sintered for 14 h. The lanthanide perovskite oxide La was obtained. 0.8 Ca 0.2 CoO3.

[0088] After testing, the lanthanide perovskite oxide La obtained in Reference Example 3 of the present invention 0.8 Ca 0.2CoO3 and La 0.8 Ca 0.2 The characteristic peaks on the standard PDF card of CoO3 (PDF#36-1388) are consistent, and the crystal structure is complete.

[0089] After testing, the lanthanide perovskite oxide La obtained in Reference Example 3 of the present invention 0.8 Ca 0.2 CoO3 is a porous network material with good conductivity, which is conducive to the transmission of lithium ions.

[0090] Reference Example 4 for the Preparation of Lanthanide Perovskite Oxide LaCoO3

[0091] The only difference between this Reference Example and Reference Example 1 is that in step 1), 1.9485 g (0.0045 mol) of lanthanum nitrate hexahydrate and 1.3097 g (0.0045 mol) of cobalt nitrate hexahydrate are added to 30 mL of solvent (anhydrous ethanol:deionized water, volume ratio: 1:1); and in step 2), a lanthanide perovskite-type oxide, LaCoO3, is obtained. The remainder of the steps is the same as in Reference Example 1.

[0092] After testing, the lanthanide perovskite oxide LaCoO3 obtained in Reference Example 4 of the present invention has characteristic peaks consistent with those on the standard PDF card (PDF# 25-1060) of LaCoO3, and has a complete crystal structure.

[0093] After testing, the lanthanide perovskite oxide LaCoO3 obtained in Reference Example 4 of the present invention is a porous network material with good conductivity, which is conducive to the transmission of lithium ions.

[0094] High nickel LiNi 0.96 Co 0.03 Mn 0.01 Reference Example 5 for Preparation of O2 Positive Electrode Materials

[0095] 10.0 g of Ni with an average particle size of 4 μm was added 0.96 Co 0.03 Mn 0.01 The (OH)2 precursor (Ni 0.1036 mol, Co 0.00324 mol, Mn 0.00108 mol) and 4.65 g (0.1108 mol) of lithium hydroxide monohydrate were added to an agate mortar and ground at a speed of 150 r / min for 30 min until mixed. Then, a two-stage temperature-raising sintering was carried out in a high-purity oxygen atmosphere. The temperature was first raised to 450 ℃ at a rate of 5 ℃ / min, sintered for 4 h, and then raised to 675 ℃ at a rate of 5 ℃ / min, sintered for 12 h, and cooled to room temperature to obtain high-nickel LiNi with an average particle size of 4 μm. 0.96 Co 0.03 Mn 0.01O2 cathode material;

[0096] The Ni 0.96 Co 0.03 Mn 0.01 The (OH)2 precursor was prepared by the hydroxide co-precipitation method, and the specific operation was as follows:

[0097] 1) Add 2018.66 g (7.68 mol) of nickel sulfate hexahydrate, 67.48 g (0.24 mol) of cobalt sulfate heptahydrate, and 13.52 g (0.08 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.

[0098] 2) Add 399.96 g (10 mol) of NaOH to 2 L of deionized water to prepare a 5 mol / L NaOH solution.

[0099] 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 solution. At the same time, the NaOH solution obtained in step 2) was introduced into the reactor to adjust the pH of the reaction system to 11.45.

[0100] 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 4 μm. Then stop stirring and age for 12 h. Wash, filter and dry the filter cake to obtain Ni 0.96 Co 0.03 Mn 0.01 (OH)2 precursor material.

[0101] Lanthanide perovskite type La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 O2 positive electrode material embodiment 1

[0102] The lanthanide perovskite type La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The O2 positive electrode material is the lanthanide perovskite oxide La obtained in Reference Example 1. 0.8 Ca 0.2 The CoO3 coating layer is coated with the high nickel LiNi obtained in Reference Example 5 at a mass ratio of 0.015:1 0.96 Co 0.03Mn 0.01 Spherical particles formed by O2 positive electrode material; the LiNi 0.96 Co 0.03 Mn 0.01 O2 is a typical layered structure, and the three elements Ni, Co, and Mn are evenly distributed in the high nickel ternary positive electrode material; the lanthanide perovskite type La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The average particle size of the O2 positive electrode material is 4 μm; the lanthanide perovskite oxide La 0.8 Ca 0.2 The average thickness of the CoO3 coating is 3 nm.

[0103] like Figure 3 As shown, the lanthanide perovskite La in the embodiment of the present invention 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The characteristic peaks of the O2 cathode material are consistent with those of the standard PDF card (PDF#74-0919) of LiNiO2, indicating that LiNi 0.96 Co 0.03 Mn 0.01 After being coated, the structure of O2 is not destroyed and still shows a typical layered structure.

[0104] like Figure 4 As shown, the lanthanide perovskite La in the embodiment of the present invention 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The morphology of the O2 cathode material is well inherited from Ni 0.96 Co 0.03 Mn 0.01 The morphology of the (OH)2 precursor is that the secondary particles are spherical with an average particle size of 4 μm. A layer of lanthanide perovskite La is formed on the surface of the secondary particles. 0.8 Ca 0.2 CoO3 coating layer.

[0105] like Figure 5 As shown, the lanthanide perovskite La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The surface of the O2 cathode material is coated with a layer of La 0.8 Ca0.2 CoO3 perovskite phase material, with an average thickness of 3 nm and a lattice spacing d of 0.228 nm in region I, corresponding to La 0.8 Ca 0.2 The (202) plane of CoO3 and the interplanar spacing d of region II are 0.205 nm, corresponding to the layered ternary LiNi 0.96 Co 0.03 Mn 0.01 (104) crystal plane of O2 positive electrode material.

[0106] Lanthanide perovskite type La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 Example 1 of the preparation method of O2 positive electrode material

[0107] 0.03 g of the lanthanide perovskite oxide La obtained in Reference Example 1 was added 0.8 Ca 0.2 CoO3 and 2.0 g of high nickel LiNi obtained in Reference Example 5 0.96 Co 0.03 Mn 0.01 The O2 positive electrode material was ball-milled at a rotation speed of 180 r / min for 6 h, heated to 500 °C at a rate of 5 °C / min in an argon atmosphere, and sintered at a low temperature for 6 h.

[0108] In order to test the lanthanide perovskite La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 Electrochemical properties of O2 positive electrode materials, battery assembly: weigh 0.08 g of lanthanide perovskite La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 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 slurry; the obtained slurry 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 / L LiPF6 / 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.

[0109] like Figure 6As shown, the lanthanide perovskite La in the embodiment of the present invention 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The battery assembled with O2 positive electrode material has a discharge capacity of 222.9 mAh / g, 201.6 mAh / g and 192.2 mAh / g at current densities of 0.2 C (40 mAh / g), 5 C and 10 C, respectively. This shows that the perovskite material with strong structural stability is coated on the surface of the high-nickel positive electrode material, which effectively stabilizes the structure of the material and can exert a high capacity even under high rate conditions; when the current density gradually decreases from 10C rate and cycles back to 0.2C rate, the discharge capacity can still be as high as 217.5 mAh / g, indicating that the reaction of this positive electrode material is highly reversible during the charge and discharge process.

[0110] like Figure 7 As shown, the lanthanide perovskite La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The battery assembled with O2 positive electrode material has an initial discharge capacity of up to 223.1 mAh / g at a current density of 0.1 C (20 mA / g, first 3 cycles) in the voltage range of 2.7 to 4.3 V. At a current density of 1 C (200 mA / g, starting from the 4th cycle), the initial discharge capacity is 219.3 mAh / g. After 100 cycles, the discharge capacity can still reach 198.17 mAh / g, and the capacity retention rate can reach up to 90.36%, indicating that the lanthanide perovskite La in the embodiment of the present invention has a good performance. 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The O2 cathode material has good cycle stability.

[0111] Lanthanide perovskite type La 0.5 Ca 0.5 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 O2 positive electrode material embodiment 2

[0112] The lanthanide perovskite type La 0.5 Ca 0.5 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The O2 positive electrode material is the lanthanide perovskite oxide La obtained in Reference Example 2.0.5 Ca 0.5 The CoO3 coating layer is coated with the high nickel LiNi obtained in Reference Example 5 at a mass ratio of 0.02:1 0.96 Co 0.03 Mn 0.01 Spherical particles formed by O2 positive electrode material; the LiNi 0.96 Co 0.03 Mn 0.01 O2 is a typical layered structure, and the three elements Ni, Co, and Mn are evenly distributed in the high nickel ternary positive electrode material; the lanthanide perovskite type La 0.5 Ca 0.5 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The average particle size of the O2 positive electrode material is 4 μm; the lanthanide perovskite oxide La 0.5 Ca 0.5 The average thickness of the CoO3 coating is 4 nm.

[0113] After testing, the lanthanide perovskite La 0.5 Ca 0.5 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The characteristic peaks of the O2 cathode material are consistent with those of the standard PDF card (PDF#74-0919) of LiNiO2, indicating that LiNi 0.96 Co 0.03 Mn 0.01 After being coated, the structure of O2 is not destroyed and still shows a typical layered structure.

[0114] After testing, the lanthanide perovskite La 0.5 Ca 0.5 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The morphology of the O2 cathode material is well inherited from Ni 0.96 Co 0.03 Mn 0.01 The morphology of the (OH)2 precursor is that the secondary particles are spherical with an average particle size of 4 μm. A 4 nm layer of lanthanide perovskite La is formed on the surface of the secondary particles. 0.5 Ca 0.5 CoO3 coating layer.

[0115] Lanthanide perovskite type La 0.5 Ca 0.5 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01Example 2 of Preparation Method of O2 Positive Electrode Material

[0116] 0.04 g of the lanthanide perovskite oxide La obtained in Reference Example 2 was added 0.5 Ca 0.5 CoO3 and 2.0 g of high nickel LiNi obtained in Reference Example 5 0.96 Co 0.03 Mn 0.01 The O2 positive electrode material was ball-milled at a rotation speed of 170 r / min for 8 h, heated to 550 °C at a rate of 6 °C / min in an argon atmosphere, and sintered at a low temperature for 7 h.

[0117] Battery assembly: Same as Example 1.

[0118] like Figure 8 As shown, the lanthanide perovskite La 0.5 Ca 0.5 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The battery assembled with O2 positive electrode material has an initial discharge capacity of up to 232.7 mAh / g at a current density of 0.1 C (20 mA / g, first 3 cycles) in the voltage range of 2.7 to 4.3 V. At a current density of 1 C (200 mA / g, starting from the 4th cycle), the initial discharge capacity is 221.4 mAh / g. After 100 cycles, the discharge capacity can still reach 179.1 mAh / g, and the capacity retention rate can reach 80.89%, indicating that the lanthanide perovskite La in the embodiment of the present invention has a good performance. 0.5 Ca 0.5 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The O2 cathode material has good cycle stability.

[0119] Lanthanide perovskite type La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 O2 positive electrode material embodiment 3

[0120] The lanthanide perovskite type La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The O2 positive electrode material is the lanthanide perovskite oxide La obtained in Reference Example 3. 0.8 Ca 0.2The CoO3 coating layer is coated with the high nickel LiNi obtained in Reference Example 5 at a mass ratio of 0.015:1 0.96 Co 0.03 Mn 0.01 Spherical particles formed by O2 positive electrode material; the LiNi 0.96 Co 0.03 Mn 0.01 O2 is a typical layered structure, and the three elements Ni, Co, and Mn are evenly distributed in the high nickel ternary positive electrode material; the lanthanide perovskite type La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The average particle size of the O2 positive electrode material is 4 μm; the lanthanide perovskite oxide La 0.8 Ca 0.2 The average thickness of the CoO3 coating is 3 nm.

[0121] After testing, the lanthanide perovskite La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The characteristic peaks of the O2 cathode material are consistent with those of the standard PDF card (PDF#74-0919) of LiNiO2, indicating that LiNi 0.96 Co 0.03 Mn 0.01 After being coated, the structure of O2 is not destroyed and still shows a typical layered structure.

[0122] After testing, the lanthanide perovskite La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The morphology of the O2 cathode material is well inherited from Ni 0.96 Co 0.03 Mn 0.01 The morphology of the (OH)2 precursor is that the secondary particles are spherical with an average particle size of 4 μm. A 3 nm layer of lanthanide perovskite La is formed on the surface of the secondary particles. 0.8 Ca 0.2 CoO3 coating layer.

[0123] Lanthanide perovskite type La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 Example 3 of Preparation Method of O2 Positive Electrode Material

[0124] 0.045 g of the lanthanide perovskite oxide La obtained in Reference Example 3 was added 0.8 Ca 0.2 CoO3 and 3.0 g of high nickel LiNi obtained in Reference Example 5 0.96 Co 0.03 Mn 0.01 The O2 positive electrode material was ball-milled at a rotation speed of 160 r / min for 7 h, heated to 450 °C at a rate of 5 °C / min in an argon atmosphere, and sintered at low temperature for 6 h.

[0125] Battery assembly: Same as Example 1.

[0126] like Figure 9 As shown, the lanthanide perovskite La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The battery assembled with O2 positive electrode material has an initial discharge capacity of up to 213.76 mAh / g at a current density of 0.1 C (20 mA / g, first 3 cycles) in the voltage range of 2.7 to 4.3 V. At a current density of 1 C (200 mA / g, starting from the 4th cycle), the initial discharge capacity is 213.54 mAh / g. After 100 cycles, the discharge capacity can still reach 197.77 mAh / g, and the capacity retention rate can reach 92.61%, indicating that the lanthanide perovskite La in the embodiment of the present invention has a good performance. 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The O2 cathode material has good cycle stability.

[0127] Lanthanide perovskite LaCoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 O2 positive electrode material embodiment 4

[0128] The lanthanide perovskite LaCoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The O2 positive electrode material is a lanthanide perovskite oxide LaCoO3 coating layer obtained in Reference Example 4 coated with the high nickel LiNi obtained in Reference Example 5 at a mass ratio of 0.015:1. 0.96 Co 0.03 Mn 0.01 Spherical particles formed by O2 positive electrode material; the LiNi 0.96 Co 0.03Mn 0.01 O2 is a typical layered structure, and the three elements Ni, Co, and Mn are evenly distributed in the high nickel ternary positive electrode material; the lanthanide perovskite LaCoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The average particle size of the O2 positive electrode material is 4 μm; the average thickness of the lanthanide perovskite oxide LaCoO3 coating layer is 3 nm.

[0129] After testing, the lanthanide perovskite LaCoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The characteristic peaks of the O2 cathode material are consistent with those of the standard PDF card (PDF#74-0919) of LiNiO2, indicating that LiNi 0.96 Co 0.03 Mn 0.01 After being coated, the structure of O2 is not destroyed and still shows a typical layered structure.

[0130] After testing, the lanthanide perovskite LaCoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The morphology of the O2 cathode material is well inherited from Ni 0.96 Co 0.03 Mn 0.01 The morphology of the (OH)2 precursor is that the secondary particles are spherical with an average particle size of 4 μm, and a 3 nm lanthanide perovskite LaCoO3 coating layer is formed on the surface of the secondary particles.

[0131] Lanthanide perovskite LaCoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 Example 4 of the preparation method of O2 positive electrode material

[0132] 0.03 g of the lanthanide perovskite oxide LaCoO3 obtained in Reference Example 4 and 2.0 g of the high nickel LiNi obtained in Reference Example 5 were mixed. 0.96 Co 0.03 Mn 0.01 The O2 positive electrode material was ball-milled at a rotation speed of 180 r / min for 6 h, heated to 500 °C at a rate of 5 °C / min in an argon atmosphere, and sintered at a low temperature for 6 h.

[0133] Battery assembly: Same as Example 1.

[0134] After testing, the lanthanide perovskite LaCoO3 coated LiNi 0.96 Co 0.03Mn 0.01 The battery assembled with O2 positive electrode material has an initial discharge capacity of up to 225.03 mAh / g at a current density of 0.1 C (20 mA / g, first 3 cycles) in the voltage range of 2.7 to 4.3 V. At a current density of 1 C (200 mA / g, starting from the 4th cycle), the initial discharge capacity is 218.42 mAh / g. After 100 cycles, the discharge capacity can still reach 175.41 mAh / g, and the capacity retention rate can be as high as 80.30%, indicating that the lanthanide perovskite LaCoO3 coated LiNi in the embodiment of the present invention is 0.96 Co 0.03 Mn 0.01 The O2 cathode material has good cycle stability.

[0135] Comparative Example 1

[0136] This comparative example is the high nickel LiNi obtained in Reference Example 5 0.96 Co 0.03 Mn 0.01 O2 positive electrode material.

[0137] Battery assembly: Same as Example 1.

[0138] like Figure 10 As shown, the high nickel ternary LiNi 0.96 Co 0.03 Mn 0.01 The battery assembled with O2 positive electrode material has an initial discharge capacity of 237.67 mAh / g at a current density of 0.1 C (20 mA / g, first 3 cycles) in the voltage range of 2.7-4.3 V. At a current density of 1 C (200 mA / g, starting from the 4th cycle), the initial discharge capacity is 221.30 mAh / g. After 100 cycles, the discharge capacity is only 126.25 mAh / g, and the capacity retention rate is only 57.05%, indicating that the high nickel LiNi 0.96 Co 0.03 Mn 0.01 The cycling stability of O2 positive electrode materials is poor before they are coated with lanthanide perovskite oxides.

[0139] Comparative Example 2

[0140] The difference between this comparative example and method example 1 is that the lanthanide perovskite oxide La 0.8 Ca 0.2 The only difference between the preparation method of CoO3 and Reference Example 1 is that in step 1), the solvent is anhydrous ethanol; the rest is the same as Reference Example 1.

[0141] like Figure 11As shown, the lanthanide perovskite oxide La used in the comparative example of the present invention 0.8 Ca 0.2 The peak intensity of CoO3 is weak, and there are many impurity peaks, indicating that it is difficult to synthesize lanthanide perovskite oxide materials with complete crystal structure when the solvent is pure ethanol. The reason is that in the sol-gel process, hydrolysis and polycondensation reactions are key steps. If anhydrous ethanol is used, the hydrolysis reaction will be damaged, making it difficult to form the required three-dimensional network structure. In addition, anhydrous ethanol is volatile, which will cause the reaction rate to be too fast, resulting in incomplete reaction.

[0142] like Figure 12 As shown, the lanthanide perovskite type La used in the comparative example of the present invention 0.8 Ca 0.2 The CoO3-coated material has an irregular block structure with only trace pores and does not form a favorable conductive network structure. This indicates that during the sol-gel process, the pure anhydrous ethanol system cannot synthesize the required three-dimensional network structure. The reason is that anhydrous ethanol has a low polarity and cannot effectively dissolve metal salts, resulting in poor dispersion of the metal salt mixed solution, which in turn affects the physical properties of the product, such as structure and morphology.

[0143] Battery assembly: Same as Example 1.

[0144] like Figure 13 As shown, the lanthanide perovskite La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The battery assembled with O2 positive electrode material has an initial discharge capacity of 202.31 mAh / g at a current density of 0.1 C (20 mA / g, first 3 cycles) in the voltage range of 2.7 to 4.3 V. At a current density of 1 C (200 mA / g, starting from the 4th cycle), the initial discharge capacity is 198.42 mAh / g. After 100 cycles, the discharge capacity is only 153 mAh / g, and the capacity retention rate is only 77.11%, indicating that the synthesized crystal structure is incomplete and the irregular morphology of the lanthanide perovskite oxide coated on the surface of the high nickel ternary material will inhibit the capacity. At the same time, the perovskite La synthesized by the mixed solvent in the embodiment of the present invention is not as good as that of the lanthanide perovskite oxide. 0.8 Ca 0.2 Compared with the CoO3 coating effect, the stability is poor.

[0145] Comparative Example 3

[0146] The difference between this comparative example and method example 1 is that the lanthanide perovskite oxide La 0.8 Ca 0.2 CoO3 coated LiNi0.96 Co 0.03 Mn 0.01 The preparation method of O2 is wet coating, and the specific preparation method is as follows:

[0147] 1) Add 0.0485 g (0.112 mmol) of lanthanum nitrate hexahydrate, 0.0066 g (0.028 mmol) of calcium nitrate tetrahydrate, and 0.0407 g (0.14 mmol) of cobalt nitrate hexahydrate to 15 mL of solvent (anhydrous ethanol to deionized water, volume ratio: 1:1) and ultrasonically disperse them at a frequency of 50 kHz for 2 h to obtain a metal ion mixed solution. Add 0.0294 g (0.14 mmol) of citric acid monohydrate to 5 mL of solvent (anhydrous ethanol to deionized water, volume ratio: 1:1) and ultrasonically disperse them at a frequency of 50 kHz for 2 h to obtain a 0.028 mol / L citric acid solution.

[0148] 2) 5 mL of 0.028 mol / L citric acid solution obtained in step 1) was added dropwise at a rate of 90 mL / h to 15 mL of the metal ion mixed solution obtained in step 1) stirred at a stirring speed of 300 r / min. The reaction was stirred for 12 h in a water bath at a temperature of 25 °C and a stirring speed of 300 r / min. Then, 2 g of Ni prepared in Reference Example 5 was added. 0.96 Co 0.03 Mn 0.01 The (OH)2 precursor was heated to 50 °C and stirred for 10 h at 50 °C and 300 r / min to form a gel. It was then vacuum dried at 100 °C and -0.07 MPa for 10 h to obtain Ni 0.96 Co 0.03 Mn 0.01 (OH)2 precursor coated powder;

[0149] 3) 1 g (0.0106 mol) of Ni obtained in step 2) 0.96 Co 0.03 Mn 0.01 The (OH)2 precursor coated powder and 0.455g (0.0108 mol) of lithium hydroxide monohydrate were added to an agate mortar and ground at a speed of 150r / min for 0.5h until mixed. Then, a two-stage temperature rising sintering was carried out in a high-purity oxygen atmosphere. The temperature was first raised to 450℃ at a rate of 5℃ / min, sintered for 4h, and then raised to 675℃ at a rate of 5℃ / min, sintered for 12h, and cooled to room temperature to obtain lanthanide perovskite La with an average particle size of 4μm. 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03Mn 0.01 O2 positive electrode material.

[0150] Battery assembly: Same as Example 1.

[0151] like Figure 14 As shown, the comparative example of the present invention is lanthanide perovskite type La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The battery assembled with O2 positive electrode material has an initial discharge capacity of 235.95 mAh / g at a current density of 0.1 C (20 mA / g, first 3 cycles) in the voltage range of 2.7 to 4.3 V. At a current density of 1 C (200 mA / g, starting from the 4th cycle), the initial discharge capacity is 221.28 mAh / g. After 100 cycles, the discharge capacity is only 165.12 mAh / g, and the capacity retention rate is only 74.62%, indicating that although the lanthanide perovskite La 0.8 Ca 0.2 CoO3 coated LiNi 0.96 Co 0.03 Mn 0.01 The initial capacity of the O2 positive electrode material is higher, but the cycle stability is poorer than that of the material obtained by solid phase coating in the embodiment of the present invention. The reason is that although the liquid phase coating process does not ball mill the high nickel ternary positive electrode material, which can reduce the damage to the secondary particles and make its initial capacity higher, the Ni in this comparative example is not as good as the Ni in the comparative example. 0.96 Co 0.03 Mn 0.01 After the (OH)2 precursor is coated by the liquid phase, it cannot be ball-milled at high speed due to the secondary particles. That is, the perovskite oxide material coating layer cannot be ball-milled at 600 r / min after forming a gel as in step 2 of reference example 1. Its particles may be large and unevenly distributed, which will result in a larger volume of the final perovskite material, thereby weakening its performance and ultimately leading to poor cycle stability after coating.

Claims

1. A lanthanide perovskite oxide-coated high-nickel ternary cathode material, characterized by: The lanthanide perovskite oxide coated high nickel ternary positive electrode material is a spherical particle formed by coating a high nickel ternary positive electrode material with a lanthanide perovskite oxide coating layer at a mass ratio of 0.01 to 0.03:1; the chemical formula of the lanthanide perovskite oxide is La z Ca 1- z CoO3, wherein 0.5≤z<1.0; the chemical formula of the high nickel ternary positive electrode material is LiNi x Co y Mn (1-x-y) O2, wherein 0.80≤x≤0.96, 0.01≤y≤0.10, 1-xy>0; the high-nickel ternary positive electrode material has a layered structure, and the three elements Ni, Co, and Mn are evenly distributed in the high-nickel ternary positive electrode material.

2. The lanthanide perovskite oxide-coated high-nickel ternary cathode material according to claim 1, characterized in that: The average particle size of the lanthanide perovskite oxide-coated high-nickel ternary positive electrode material is 2 to 8 μm; the average thickness of the lanthanide perovskite oxide coating layer is 2 to 6 nm.

3. A method for preparing the lanthanide perovskite oxide-coated high-nickel ternary cathode material according to claim 1 or 2, characterized in that: The lanthanide perovskite oxide is mixed with the high nickel ternary positive electrode material by ball milling, and then sintered at low temperature under a protective atmosphere.

4. The method for preparing the lanthanide perovskite-type oxide-coated high-nickel ternary cathode material according to claim 3, characterized in that: The mass ratio of the lanthanide perovskite oxide to the high-nickel ternary positive electrode material is 0.01-0.03:1; the rotation speed of the ball milling mixing is 100-300 r / min, and the time is 2-10 h; the protective atmosphere includes argon and / or nitrogen; the low-temperature sintering is to increase the temperature to 300-550°C at a rate of 1-10°C / min and sinter for 2-10 h.

5. The method for preparing the lanthanide perovskite oxide-coated high-nickel ternary cathode material according to claim 3 or 4, characterized in that: The preparation method of the lanthanide perovskite-type oxide comprises the following steps: 1) adding a lanthanum source, a calcium source, and a cobalt source into a solvent, and ultrasonically dispersing them to obtain a metal ion mixed solution; adding a complexing agent into the solvent, and ultrasonically dispersing them to obtain a complexing agent solution; 2) adding the complexing agent solution obtained in step 1) dropwise to the metal ion mixed solution obtained in step 1), or adding the metal ion mixed solution obtained in step 1) dropwise to the complexing agent solution obtained in step 1), performing a stirring reaction, heating, performing a second stirring reaction, drying, ball milling, sintering in an oxidizing atmosphere, and cooling to room temperature to obtain a lanthanide perovskite-type oxide.

6. The method for preparing the lanthanide perovskite oxide-coated high-nickel ternary cathode material according to claim 5, characterized in that: In step 1), the molar ratio of lanthanum in the lanthanum source, calcium in the calcium source, and cobalt in the cobalt source is 0.5-1.0:0-0.5:1; the total molar concentration of metal ions in the metal ion mixed solution is 0.1-0.9 mol / L; the lanthanum source includes lanthanum nitrate, lanthanum acetate or lanthanum chloride, and one or more of their hydrates; the calcium source includes calcium nitrate, calcium acetate or calcium chloride, and one or more of their hydrates; the cobalt source includes cobalt nitrate, cobalt acetate or cobalt chloride, and one or more of their hydrates; the concentration of the complexing agent solution is 0.1-0.8 mol / L; the complexing agent includes one or more of citric acid, ethylenediaminetetraacetic acid or ethylene glycol; the solvents are mixed solvents of anhydrous ethanol and deionized water in a volume ratio of 1:1-3; the frequency of the ultrasonic dispersion is 30-60 kHz, and the time is 1-4 h.

7. The method for preparing the lanthanide perovskite oxide-coated high-nickel ternary cathode material according to claim 5, characterized in that: In step 2), the volume ratio of the complexing agent solution to the metal ion mixed solution is 1:0.4-4.0; the molar ratio of the complexing agent in the complexing agent solution to the cobalt ion in the metal ion mixed solution is 1.0-1.5:1; the dropwise addition rate is 60-120 mL / h; during the dropwise addition, the added metal ion mixed solution or complexing agent solution is stirred at a stirring speed of 100-600 r / min; the temperature of the primary stirring reaction is 20-30 ° C, the stirring speed is 100-600 r / min, and the time is 10-20 h; the temperature is raised to 30-80 ° C; the temperature of the secondary stirring reaction is 30-80 ° C, the stirring speed is 100-600 r / min, and the time is 8-14 h; the drying is vacuum drying; the vacuum drying temperature is 80-120 ° C, the vacuum degree is -0.06-0.09 MPa, and the time is 6-12 h; the ball milling speed is 300-700 r / min, and the time is 2-10 h; the oxidizing atmosphere includes an oxygen atmosphere and / or an air atmosphere; and the sintering is a two-stage temperature-raising sintering, firstly heating to 350-550°C at a rate of 1-10°C / min, sintering for 2-10 h, and then heating to 600-900°C at a rate of 1-10°C / min, and sintering for 9-16 h.

8. The method for preparing the lanthanide perovskite oxide-coated high-nickel ternary cathode material according to claim 6, characterized in that: In step 2), the volume ratio of the complexing agent solution to the metal ion mixed solution is 1:0.4-4.0; the molar ratio of the complexing agent in the complexing agent solution to the cobalt ion in the metal ion mixed solution is 1.0-1.5:1; the dropwise addition rate is 60-120 mL / h; during the dropwise addition, the added metal ion mixed solution or complexing agent solution is stirred at a stirring speed of 100-600 r / min; the temperature of the primary stirring reaction is 20-30 ° C, the stirring speed is 100-600 r / min, and the time is 10-20 h; the temperature is raised to 30-80 ° C; the temperature of the secondary stirring reaction is 30-80 ° C, the stirring speed is 100-600 r / min, and the time is 8-14 h; the drying is vacuum drying; the vacuum drying temperature is 80-120 ° C, the vacuum degree is -0.06-0.09 MPa, and the time is 6-12 h; the ball milling speed is 300-700 r / min, and the time is 2-10 h; the oxidizing atmosphere includes an oxygen atmosphere and / or an air atmosphere; and the sintering is a two-stage temperature-raising sintering, firstly heating to 350-550°C at a rate of 1-10°C / min, sintering for 2-10 h, and then heating to 600-900°C at a rate of 1-10°C / min, and sintering for 9-16 h.

9. The method for preparing the lanthanide perovskite-type oxide-coated high-nickel ternary cathode material according to claim 3 or 4, characterized in that: 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 chemical formula of the nickel cobalt manganese hydroxide precursor is Ni x Co y Mn (1-x-y) (OH)2, wherein 0.80≤x≤0.96, 0.01≤y≤0.10, and 1-xy>0; the average particle size of the nickel cobalt manganese hydroxide precursor is 2-8 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 1:1.01-1.08; the lithium source includes LiOH·H2O and / or Li2CO3; the grinding speed is 100-300 r / min, and the time is 12-48 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 2-6 h, and then heating to 550-800°C at a rate of 1-10°C / min, and sintering for 8-14 h.

10. The method for preparing the lanthanide perovskite oxide-coated high-nickel ternary cathode material according to claim 5, characterized in that: 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 chemical formula of the nickel cobalt manganese hydroxide precursor is Ni x Co y Mn (1-x-y) (OH)2, wherein 0.80≤x≤0.96, 0.01≤y≤0.10, and 1-xy>0; the average particle size of the nickel cobalt manganese hydroxide precursor is 2-8 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 1:1.01-1.08; the lithium source includes LiOH·H2O and / or Li2CO3; the grinding speed is 100-300 r / min, and the time is 12-48 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 2-6 h, and then heating to 550-800°C at a rate of 1-10°C / min, and sintering for 8-14 h.

11. The method for preparing the lanthanide perovskite-type oxide-coated high-nickel ternary cathode material according to claim 6, characterized in that: 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 chemical formula of the nickel cobalt manganese hydroxide precursor is Ni x Co y Mn (1-x-y) (OH)2, wherein 0.80≤x≤0.96, 0.01≤y≤0.10, and 1-xy>0; the average particle size of the nickel cobalt manganese hydroxide precursor is 2-8 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 1:1.01-1.08; the lithium source includes LiOH·H2O and / or Li2CO3; the grinding speed is 100-300 r / min, and the time is 12-48 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 2-6 h, and then heating to 550-800°C at a rate of 1-10°C / min, and sintering for 8-14 h.

12. The method for preparing the lanthanide perovskite-type oxide-coated high-nickel ternary cathode material according to claim 7, characterized in that: 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 chemical formula of the nickel cobalt manganese hydroxide precursor is Ni x Co y Mn (1-x-y) (OH)2, wherein 0.80≤x≤0.96, 0.01≤y≤0.10, and 1-xy>0; the average particle size of the nickel cobalt manganese hydroxide precursor is 2-8 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 1:1.01-1.08; the lithium source includes LiOH·H2O and / or Li2CO3; the grinding speed is 100-300 r / min, and the time is 12-48 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 2-6 h, and then heating to 550-800°C at a rate of 1-10°C / min, and sintering for 8-14 h.

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