Preparation and application of Al2O3-coated lithium ion battery high-nickel cobalt-free positive electrode material
By constructing an Al2O3 coating layer on the surface of the cathode material of lithium-ion batteries, the problem of nickel-manganese-aluminum materials reacting in air was solved, the cycle stability and thermal stability of the battery were improved, and long-term operation of high-energy-density batteries was achieved.
Patent Information
- Application Number
- CN202511669879.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-14
- Publication Date
- 2026-02-10
AI Technical Summary
Nickel-manganese-aluminum cathode materials for lithium-ion batteries are prone to reacting with moisture and carbon dioxide in the air, resulting in the residue of alkaline compounds on the surface, which affects the battery manufacturing yield and cycle performance. Furthermore, the structure is prone to degradation during cycling, limiting its commercial application.
A dense Al2O3 coating layer was constructed on the surface of nickel manganese aluminum (NMA) material using the sol-gel method to form a core-shell structure. The bonding strength was enhanced by annealing at 800℃, and a physical isolation layer was constructed at the interface to suppress side reactions.
It significantly improves the cycling and thermal stability of the material, suppresses capacity decay and electrode degradation, and enhances the cycle life and high energy density performance of the battery.
Smart Images
Figure CN121506901A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-ion battery manufacturing technology, specifically relating to the preparation and application of an Al2O3-coated high-nickel cobalt-free cathode material for lithium-ion batteries. Background Technology
[0002] Lithium-ion batteries have shown great application potential in electric vehicles and energy storage. Among the many cathode materials for lithium-ion batteries, nickel-manganese-aluminum (NiMA) materials have attracted widespread attention due to their high theoretical capacity, simple preparation process, and low cost. However, this type of cathode material still faces several key challenges: First, its air stability is poor, easily reacting with moisture and carbon dioxide in the air, leading to a significant increase in the residual alkaline compounds on the material surface. These residual alkaline substances can further induce gelation of the electrode slurry during preparation, causing difficulties in coating, reduced uniformity, and seriously affecting the manufacturing yield and process stability of the battery. Second, residual alkali on the surface can also catalyze the decomposition of the electrolyte, causing the loss of active lithium ions, thereby reducing the reversible capacity of the material and triggering severe gas generation, which not only affects the energy density and cycle life of the battery but also brings potential safety hazards. In addition, cathode materials often undergo complex phase transitions and structural degradation during cycling, further limiting their long-term cycle performance and large-scale commercial applications. Summary of the Invention
[0003] The purpose of this invention is to provide a preparation and application of an Al2O3-coated high-nickel cobalt-free cathode material for lithium-ion batteries. The use of an Al2O3 oxide coating layer can construct a physical isolation layer between the cathode material and the electrolyte, which can suppress interfacial side reactions to a certain extent, help reduce gas generation during battery cycling, and improve the cycling stability of the material, thereby improving the overall electrochemical performance of the cathode material.
[0004] The specific technical solution adopted by this invention is as follows: A method for preparing an Al2O3-coated high-nickel, cobalt-free cathode material for lithium-ion batteries includes the following steps: Step 1: Aluminum oxide (Al2O3) was selected as the coating material based on ion migration efficiency, interfacial compatibility, and thermal stability, and uniform coating was achieved through sol-gel technology. In step 1, 0.02 g of aluminum isopropoxide (Al(OCH(CH3)2)3) is dissolved in 10 ml of anhydrous ethanol and magnetically stirred at 60 °C for 2 h until completely dissolved, forming a clear and transparent sol precursor solution.
[0005] Step 2: A dense and continuous aluminum oxide (Al2O3) coating layer is constructed on the surface of nickel manganese aluminum (NMA) material using a wet chemical method, with the coating thickness controlled at 1-10 nm to balance ion conductivity and interface protection. In step 2, firstly, 2.00g of spherical nickel-manganese-aluminum (NMA) precursor is slowly added to the sol precursor solution from step 1; the NMA precursor has a particle size of 5-15μm and a Ni:Mn:Al ratio of 90:5:5; it is continuously stirred for 24 hours in an oil bath at 60℃ to fully wet the surface of the NMA particles and adsorb the aluminum source; then, the above mixture is transferred to a vacuum drying oven and the solvent is slowly evaporated at 100℃ to allow aluminum isopropoxide to uniformly hydrolyze and condense on the surface of the NMA, forming a gel coating layer.
[0006] Step 3: Enhance the bonding strength between the aluminum oxide (Al2O3) coating layer and the nickel manganese aluminum (NMA) matrix by annealing at 800℃ to form a stable interface structure; In step 3, the coated material is ground with lithium hydroxide at a molar ratio of 1:1.05 and then placed in a muffle furnace. The temperature is increased to 400°C at 5°C / min under air atmosphere and held for 4 hours. The temperature is then increased to 800°C at 5°C / min and held for 12 hours to complete the crystallization treatment of the alumina coating layer, thus obtaining the Al2O3-coated LNMA cathode material LNMA-Al2O3.
[0007] Step 4: Mix the coated nickel-manganese-aluminum (NMA) material with a conductive agent and a binder to form an electrode slurry, which is then coated onto the current collector. After drying and pressing, an electrode sheet is obtained.
[0008] In step 4: First, the heat-treated positive electrode material LNMA-Al2O3 is mixed with conductive carbon black SuperP and polyvinylidene fluoride PVDF binder at a mass ratio of 8:1:1, and an electrode slurry is prepared using N-methylpyrrolidone (NMP) as a solvent; then, the slurry is uniformly coated onto an aluminum foil current collector, dried under vacuum at 80°C for 6 hours, and then rolled at a pressure of 10 MPa to obtain a positive electrode sheet.
[0009] The high-nickel, cobalt-free cathode material for lithium-ion batteries is used to prepare the positive electrode sheet for lithium-ion batteries. The positive electrode sheet is then punched to the required specifications, such as a diameter of 12 mm, and assembled into a half-cell or a full-cell battery.
[0010] The technical effects achieved by this invention are as follows: This invention constructs a uniform and dense alumina Al2O3 coating layer on the surface of a nickel manganese aluminum (NMA) precursor using a sol-gel method, forming a modified cathode material with a core-shell structure. This invention applies the prepared Al2O3-coated LNMA material to the cathode of a lithium-ion battery. When this material is used as the cathode, it significantly improves the overall performance of the battery. First, the Al2O3 coating layer can effectively suppress side reactions between the LNMA material and the electrolyte, reduce transition metal dissolution, and thus improve the structural stability of the electrode under high voltage conditions. Second, as an artificial interface layer, the Al2O3 coating layer can optimize the ion transport kinetics at the electrode-electrolyte interface, promote uniform lithium ion migration, and reduce interfacial impedance. Finally, the thermal stability and mechanical strength of the coating layer can effectively alleviate volumetric strain during cycling and suppress the generation and propagation of particle cracks.
[0011] In summary, the Al2O3-coated LNMA cathode material prepared in this invention significantly enhances interface stability, thermal stability, and structural integrity when applied to lithium-ion batteries, effectively suppressing capacity decay and electrode degradation. Therefore, this modified cathode material exhibits excellent cycle life and rate performance under high-voltage charge-discharge conditions of ≥4.3V, while also enabling long-term stable operation of high-energy-density batteries. Attached Figure Description
[0012] Figure 1 These are the transmission thickness analysis results of the packaging material prepared by this invention; Figure 2 These are the scanning results of Al2O3-encapsulated and unencapsulated materials prepared in this invention; Figure 3 This is a schematic diagram of the long-cycle performance test at 0.5C rate of full cells constructed by matching the Al2O3-encapsulated and unencapsulated materials prepared in this invention with lithium anodes. Detailed Implementation
[0013] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.
[0014] like Figure 1 as well as Figure 2 As shown, a method for preparing an Al2O3-coated high-nickel, cobalt-free cathode material for lithium-ion batteries includes the following steps: Step 1: Aluminum oxide (Al2O3) was selected as the coating material based on ion migration efficiency, interfacial compatibility, and thermal stability, and uniform coating was achieved through sol-gel technology. In step 1, 0.02 g of aluminum isopropoxide (Al(OCH(CH3)2)3) is dissolved in 10 ml of anhydrous ethanol and magnetically stirred at 60 °C for 2 h until completely dissolved, forming a clear and transparent sol precursor solution.
[0015] Step 2: A dense and continuous aluminum oxide (Al2O3) coating layer is constructed on the surface of nickel manganese aluminum (NMA) material using a wet chemical method, with the coating thickness controlled at 1-10 nm to balance ion conductivity and interface protection. In step 2, firstly, 2.00g of spherical nickel-manganese-aluminum (NMA) precursor is slowly added to the sol precursor solution from step 1; the NMA precursor has a particle size of 5-15μm and a Ni:Mn:Al ratio of 90:5:5; it is continuously stirred for 24 hours in an oil bath at 60℃ to fully wet the surface of the NMA particles and adsorb the aluminum source; then, the above mixture is transferred to a vacuum drying oven and the solvent is slowly evaporated at 100℃ to allow aluminum isopropoxide to uniformly hydrolyze and condense on the surface of the NMA, forming a gel coating layer.
[0016] Step 3: Enhance the bonding strength between the aluminum oxide (Al2O3) coating layer and the nickel manganese aluminum (NMA) matrix by annealing at 800℃ to form a stable interface structure; In step 3, the coated material is ground with lithium hydroxide at a molar ratio of 1:1.05 and then placed in a muffle furnace. The temperature is increased to 400°C at 5°C / min under air atmosphere and held for 4 hours. The temperature is then increased to 800°C at 5°C / min and held for 12 hours to complete the crystallization treatment of the alumina coating layer, thus obtaining the Al2O3-coated LNMA cathode material LNMA-Al2O3.
[0017] Step 4: Mix the coated nickel-manganese-aluminum (NMA) material with a conductive agent and a binder to form an electrode slurry, which is then coated onto the current collector. After drying and pressing, an electrode sheet is obtained.
[0018] In step 4: First, the heat-treated positive electrode material LNMA-Al2O3 is mixed with conductive carbon black SuperP and polyvinylidene fluoride PVDF binder at a mass ratio of 8:1:1, and an electrode slurry is prepared using N-methylpyrrolidone (NMP) as a solvent; then, the slurry is uniformly coated onto an aluminum foil current collector, dried under vacuum at 80°C for 6 hours, and then rolled at a pressure of 10 MPa to obtain a positive electrode sheet.
[0019] The high-nickel, cobalt-free cathode material for lithium-ion batteries is used to prepare the positive electrode sheet for lithium-ion batteries. The positive electrode sheet is then punched to the required specifications, such as a diameter of 12 mm, and assembled into a half-cell or a full-cell battery.
[0020] In this invention, the positive electrode sheet is punched into a circular piece with a diameter of 12 mm, a lithium metal sheet is used as the counter electrode, Celgard 2500 is used as the separator, and 1.0 M LiPF6 in EC:DEC:EMC=1:1:1 (Vol%) is used as the electrolyte. The CR2032 coin cell is assembled in an argon glove box; in the argon glove box: H2O<0.1ppm, O2<0.1ppm; In this invention, a battery testing system is used to test electrochemical performance: cycle performance is tested at a rate of 0.5C within a voltage range of 2.7-4.5V, where 1C = 200mA / g; rate performance is tested at different rates from 0.2C to 5C; and interface characteristics are analyzed using electrochemical impedance spectroscopy (EIS).
[0021] In the above steps of the present invention, steps 1-3 are the material synthesis stage, which needs to be carried out in a dry air environment; in step 4 and the subsequent electrode preparation and battery assembly stages, except for slurry preparation, all other operations are completed in a glove box.
[0022] Transmission electron microscopy (TEM) images of the LNMA-Al2O3 cathode material prepared in this invention are shown below. Figure 1 As shown, a continuous Al₂O₃ coating layer with a thickness of approximately 5 nm is uniformly covered on the surface of NMA particles. The coating layer thickness and uniformity can be precisely controlled using a sol-gel combined with rotary evaporation process, making it suitable for large-scale production.
[0023] In this invention: Figure 1 To obtain the transmission thickness analysis results and related morphological images of the prepared encapsulation material, controllable encapsulation technology can achieve precise control of the encapsulation thickness and repeatable experimental preparation. Figure 2 The long-term cycling performance of full cells constructed with Al2O3-coated and uncoated materials and matched with lithium anodes was tested at 0.5C rate. For the coated sample, it retained 88% capacity retention after 100 cycles. The results indicate that the coating treatment used in this embodiment can significantly improve the cycling stability of the electrode under practical application conditions. Figure 3 This is a schematic diagram of the long-cycle performance test at 0.5C rate of full cells constructed by matching the Al2O3-encapsulated and unencapsulated materials prepared in this invention with lithium anodes.
[0024] In summary, the coating material selected in this invention is aluminum isopropoxide (Al(OCH(CH3)2)3), and the solvent is anhydrous ethanol. Alumina coating is achieved via a sol-gel method. The substrate material selected in this invention is a spherical nickel-manganese-aluminum (NMA) precursor with a particle size of 5-15 μm.
[0025] This invention achieves uniform coating of alumina on the surface of an NMA precursor using a stirring solvothermal method, with the coating thickness controlled within 1-10 nm. The mass ratio of aluminum isopropoxide to the NMA precursor is set to 0.5-1.5:100, and the amount of solvent ethanol is five times the mass of the precursor. The alumina coating is solidified by a programmed temperature rise heat treatment: holding at 400°C for 4 hours, followed by raising the temperature to 800°C and holding for 12 hours. This allows for batch repeatability of the coating process and precise control of the coating thickness.
[0026] This invention constructs a uniform and dense alumina Al2O3 coating layer on the surface of a nickel manganese aluminum (NMA) precursor using a sol-gel method, forming a modified cathode material with a core-shell structure. This invention applies the prepared Al2O3-coated LNMA material to the cathode of a lithium-ion battery. When this material is used as the cathode, it significantly improves the overall performance of the battery. First, the Al2O3 coating layer can effectively suppress side reactions between the LNMA material and the electrolyte, reduce transition metal dissolution, and thus improve the structural stability of the electrode under high voltage conditions. Second, as an artificial interface layer, the Al2O3 coating layer can optimize the ion transport kinetics at the electrode-electrolyte interface, promote uniform lithium ion migration, and reduce interfacial impedance. Finally, the thermal stability and mechanical strength of the coating layer can effectively alleviate volumetric strain during cycling and suppress the generation and propagation of particle cracks.
[0027] In summary, the Al2O3-coated LNMA cathode material prepared in this invention significantly enhances interface stability, thermal stability, and structural integrity when applied to lithium-ion batteries, effectively suppressing capacity decay and electrode degradation. Therefore, this modified cathode material exhibits excellent cycle life and rate performance under high-voltage charge-discharge conditions of ≥4.3V, while also enabling long-term stable operation of high-energy-density batteries.
[0028] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention are implemented according to conventional methods in the art unless otherwise specified or limited.
Claims
1. A method for preparing an Al2O3-coated high-nickel, cobalt-free cathode material for lithium-ion batteries, characterized in that: Includes the following steps: Step 1: Aluminum oxide (Al2O3) was selected as the coating material based on ion migration efficiency, interfacial compatibility, and thermal stability, and uniform coating was achieved through sol-gel technology. Step 2: A dense and continuous aluminum oxide (Al2O3) coating layer is constructed on the surface of nickel manganese aluminum (NMA) material using a wet chemical method, with the coating thickness controlled at 1-10 nm to balance ion conductivity and interface protection. Step 3: Enhance the bonding strength between the aluminum oxide (Al2O3) coating layer and the nickel manganese aluminum (NMA) matrix by annealing at 800℃ to form a stable interface structure; Step 4: Mix the coated nickel-manganese-aluminum (NMA) material with a conductive agent and a binder to form an electrode slurry, which is then coated onto the current collector. After drying and pressing, an electrode sheet is obtained.
2. The preparation method according to claim 1, characterized in that: In step 1, 0.02 g of aluminum isopropoxide (Al(OCH(CH3)2)3) is dissolved in 10 ml of anhydrous ethanol and magnetically stirred at 60 °C for 2 h until completely dissolved, forming a clear and transparent sol precursor solution.
3. The preparation method according to claim 1, characterized in that: In step 2, First: Weigh 2.00g of spherical nickel manganese aluminum NMA precursor and slowly add it to the sol precursor solution in step 1; the nickel manganese aluminum NMA precursor has a particle size of 5-15μm and a Ni:Mn:Al ratio of 90:5:5; stir continuously for 24h in an oil bath at 60℃ to fully wet the surface of the nickel manganese aluminum NMA particles and adsorb the aluminum source. Then, the above mixture was transferred to a vacuum drying oven and the solvent was slowly evaporated at 100°C to allow aluminum isopropoxide to hydrolyze and condense uniformly on the surface of nickel manganese aluminum (NMA) to form a gel coating layer.
4. The preparation method according to claim 1, characterized in that: In step 3, the coated material is ground with lithium hydroxide at a molar ratio of 1:1.05 and then placed in a muffle furnace. The temperature is increased to 400°C at 5°C / min under air atmosphere and held for 4 hours. The temperature is then increased to 800°C at 5°C / min and held for 12 hours to complete the crystallization treatment of the alumina coating layer, thus obtaining the Al2O3-coated LNMA cathode material LNMA-Al2O3.
5. The preparation method according to claim 1, characterized in that: In step 4: First, heat-treated positive electrode material LNMA-Al2O3 is mixed with conductive carbon black SuperP and polyvinylidene fluoride PVDF binder at a mass ratio of 8:1:1, and electrode slurry is prepared using N-methylpyrrolidone NMP as solvent. Then: the slurry is uniformly coated onto the aluminum foil current collector, dried under vacuum at 80°C for 6 hours, and then rolled at 10MPa pressure to obtain the positive electrode sheet.
6. The high-nickel, cobalt-free positive electrode material for lithium-ion batteries prepared by the preparation method according to any one of claims 1-5 is used to prepare positive electrode sheets for lithium-ion batteries, wherein the positive electrode sheets are punched to the required specifications and assembled into half-cells or full-cells.