Positive electrode material and preparation method thereof, pole piece, battery, battery pack and electric equipment

Abstract

The invention discloses a positive electrode material and a preparation method thereof, a pole piece, a battery, a battery pack and electric equipment, the positive electrode material comprises an inner core and a coating layer coating at least part of the surface of the inner core, the inner core comprises a lithium nickel cobalt manganese oxide, and the coating layer comprises a fluorine-containing mineral material. According to the positive electrode material provided by the invention, the hydrophobicity of the surface of the positive electrode material is effectively enhanced, and the service life of the positive electrode material is prolonged.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a positive electrode material and its preparation method, an electrode sheet, a battery, a battery pack, and an electrical device. Background Technology

[0002] Lithium nickel cobalt manganese oxide (NCM) possesses advantages such as high reversible capacity and fast charge / discharge, making it one of the most popular cathode materials for lithium-ion batteries. To address issues such as transition metal dissolution, formation of an unstable cathode-electrolyte (CEI) interface layer, poor chemical stability when exposed to air, and mechanical instability, coatings are typically formed on the cathode material surface. However, in related technologies, the coatings often lack sufficient hydrophobicity, resulting in a high water content in the cathode material. This easily triggers side reactions, forming an unstable interfacial film on the cathode material surface, increasing charge transfer impedance, and leading to poor electrical performance. Therefore, a cathode material with stable electrical properties is urgently needed. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one object of the present invention is to provide a cathode material that effectively enhances the hydrophobicity of the cathode material surface and extends the service life of the cathode material.

[0004] The second objective of this invention is to provide a method for preparing the above-mentioned cathode material.

[0005] The third objective of this invention is to provide an electrode sheet using the aforementioned positive electrode material.

[0006] The fourth object of the present invention is to provide a battery using the above-mentioned positive electrode material or electrode sheet.

[0007] The fifth objective of this invention is to provide a battery pack employing the aforementioned positive electrode material, electrode sheet, or battery.

[0008] The sixth objective of this invention is to provide an electrical device that uses the above-mentioned positive electrode material, electrode sheet or battery or battery pack.

[0009] According to a first aspect of the present invention, a cathode material includes a core and a coating layer covering at least a portion of the surface of the core, the core comprising lithium nickel cobalt manganese oxide, and the coating layer comprising a fluorine-containing mineral material.

[0010] According to the cathode material of the present invention, the coating layer is a fluorine-containing mineral material. The presence of fluorine in the coating layer material enhances the hydrophobicity of the cathode material surface, reducing the adsorption and permeation of polar gases (such as water vapor). Furthermore, the fluorine-containing mineral material possesses high mechanical strength and can form a "protective layer" on the core surface, buffering the effects of Li during charging and discharging. +The volume change caused by insertion / extraction prevents structural changes in the cathode material during use, maintaining structural integrity and ensuring the lifespan of the cathode material. Furthermore, when the coating layer is a fluorine-containing mineral material, the fluorine-containing coating layer preferentially decomposes during the first charge-discharge process, forming a solid electrolyte interface film on the cathode material surface. This effectively prevents organic solvents in the electrolyte from penetrating into the core of the cathode material, reducing side reactions at the "electrolyte-cathode material" interface, improving the stability and related electrical properties of the cathode material, and extending its lifespan.

[0011] According to some embodiments of the present invention, the fluorine-containing mineral material also contains sodium and / or lithium.

[0012] According to some embodiments of the present invention, the fluorine-containing mineral material is a fluorine-modified mineral material, and the mineral material includes at least one of montmorillonite, hydrotalcite, hexagonal boron nitride, halloysite, and kaolinite; preferably, the mineral material includes montmorillonite.

[0013] According to some embodiments of the present invention, the mineral material has a nanosheet structure.

[0014] According to some embodiments of the present invention, the coating layer accounts for x% of the mass of the positive electrode material, wherein 0.05wt%≤x≤3.5wt%, preferably 0.07wt%≤x≤3wt%; and / or, the thickness of the coating layer is W, wherein W≤7.5nm, preferably 0.1nm≤W≤5nm.

[0015] According to some embodiments of the present invention, the particle size Dv50 of the positive electrode material is ≤11μm, preferably 1μm≤Dv50≤10μm; and / or, the specific surface area of ​​the positive electrode material is M, wherein M≤3.5m². 2 / g, preferably 1m 2 / g≤M≤3m 2 / g.

[0016] A method for preparing a cathode material according to a second aspect of the present invention includes the following steps: The cathode material is obtained by mixing the core and a fluorine-containing mineral material.

[0017] According to some embodiments of the present invention, the mixing of the core and the fluorine-containing mineral material specifically includes: The core, the fluorine-containing mineral material, and the solvent are mixed to obtain a mixed solution, which is then dried.

[0018] According to some embodiments of the present invention, the mixed solution further includes a binder comprising polyethyleneimine and / or polyallylamine.

[0019] According to some embodiments of the present invention, the method for preparing the fluorine-containing mineral material includes the following steps: The natural mineral material is dispersed in a fluorine-containing solution, and then dried after the reaction to obtain the fluorine-containing mineral material.

[0020] The electrode sheet according to a third aspect embodiment of the present invention includes the positive electrode material according to the first aspect embodiment described above, or the positive electrode material prepared according to the preparation method described in the second aspect embodiment described above.

[0021] A battery according to a fourth aspect embodiment of the present invention includes a positive electrode material according to the first aspect embodiment described above, or a positive electrode material prepared according to the preparation method described in the second aspect embodiment described above, or an electrode sheet according to the third aspect embodiment described above.

[0022] A battery pack according to a fifth aspect embodiment of the present invention includes a positive electrode material according to the first aspect embodiment described above, or a positive electrode material prepared by the preparation method according to the second aspect embodiment described above, or an electrode sheet according to the third aspect embodiment described above, or at least two batteries according to the fourth aspect embodiment described above.

[0023] An electrical device according to a sixth aspect embodiment of the present invention includes a positive electrode material according to the first aspect embodiment described above, or a positive electrode material prepared by the preparation method according to the second aspect embodiment described above, or an electrode sheet according to the third aspect embodiment described above, or a battery according to the fourth aspect embodiment described above, or a battery pack according to the fifth aspect embodiment described above.

[0024] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a morphology diagram of the positive electrode material according to Embodiment 1 of the present invention; Figure 2 This is a charge-discharge curve of the positive electrode material according to Embodiment 1 of the present invention. Detailed Implementation

[0026] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. Figure 1 and Figure 2 A cathode material according to an embodiment of the first aspect of the present invention is described. In the following description of this application, an example of a cathode material used in a lithium-ion battery is used, but the description is not limited thereto.

[0027] Lithium nickel cobalt manganese oxide (NCM) is one of the most popular cathode materials for lithium-ion batteries. However, some problems exist during its use, such as transition metal dissolution, formation of an unstable cathode-electrolyte interface (CEI) layer, chemical instability when exposed to air, and mechanical instability, which limit the application of lithium nickel cobalt manganese oxide in the field of cathode materials.

[0028] In related technologies, coatings are typically applied to the surface of lithium nickel cobalt manganese oxides to overcome the aforementioned problems. Common coatings for lithium nickel cobalt manganese oxide surfaces include compounds of Al, W, B, and Zr. For example, aluminum compounds (such as Al2O3 and AlPO4), tungsten compounds (such as WO3 and W2O5), boron compounds (such as B2O3, LiBO2, and BN), and zirconium compounds (such as ZrO2, ZrP2O7, and ZrF4) have limited hydrophobic effects. When the coating of the cathode material is one of these compounds, the coating is unable to effectively block the adsorption and penetration of polar gases (such as water vapor), resulting in a high water content in the cathode material. This easily triggers side reactions, forming an unstable interfacial film on the cathode material surface, increasing charge transfer resistance, and reducing the battery's charge and discharge capacity. Furthermore, it reduces the structural stability of the cathode material and further deteriorates during cycling, shortening cycle life. Therefore, this application aims to improve the hydrophobicity of the coating material and reduce the moisture content of the cathode material, thereby significantly improving the long-term stability and activity of the cathode material.

[0029] According to a first aspect of the present invention, the cathode material includes a core and a coating layer covering at least a portion of the surface of the core, the core comprising lithium nickel cobalt manganese oxide, and the coating layer comprising a fluorine-containing mineral material.

[0030] Lithium nickel cobalt manganese oxide (NCM) is an important cathode material for lithium-ion batteries, exhibiting high energy density and good cycle performance. When used as the core of a cathode material, NCM provides high energy density and can form a stable connection with the coating layer through electrostatic attraction. Furthermore, NCM maintains good structural stability over long-term use, with relatively small capacity decay after multiple cycles. Moreover, NCM possesses high electronic conductivity and lithium-ion diffusion coefficient, enabling rapid battery reactions during charge and discharge, resulting in high charge and discharge capacity and allowing for quick charging and discharging. When used in electric vehicle batteries, this cathode material meets the range requirements of electric vehicles, effectively improving battery lifespan.

[0031] For example, the presence of fluorine in the coating material can enhance the hydrophobicity of the cathode material surface, reducing the adsorption and permeation of polar gases (such as water vapor). Furthermore, fluorine-containing mineral materials possess high mechanical strength and can form a "protective layer" on the core surface, buffering the effects of Li during charging and discharging. + The volume change caused by insertion / extraction prevents structural changes in the cathode material during use, maintaining structural integrity and ensuring service life. Furthermore, when the cathode material's coating is a fluorine-containing mineral material, the fluorine-containing coating preferentially decomposes during the first charge-discharge cycle, forming a solid electrolyte interface film on the cathode material surface. This solid electrolyte interface film adheres tightly to the cathode material surface, effectively preventing organic solvents in the electrolyte from penetrating into the cathode material's core, reducing side reactions at the electrolyte-cathode interface, and extending the cathode material's service life.

[0032] For example, lithium nickel cobalt manganese oxide materials have positively charged surfaces, while fluorine-containing mineral materials have negatively charged surfaces. This creates an electrostatic attraction between the core and the coating layer, resulting in a more robust coating that is less prone to detachment during use, thus improving the stability and electrical performance of the cathode material. Furthermore, fluorine-containing mineral materials possess excellent mechanical flexibility, enabling the fabrication of cathode materials with high coverage three-dimensional coating structures, effectively improving the uniformity of the coating layer.

[0033] According to embodiments of the present invention, the cathode material has a coating layer made of fluorine-containing mineral material. The presence of fluorine in the coating layer enhances the hydrophobicity of the cathode material surface, reducing the adsorption and permeation of polar gases (such as water vapor). Furthermore, the fluorine-containing mineral material possesses high mechanical strength and can form a "protective layer" on the core surface, buffering the effects of Li during charging and discharging. + The volume change caused by insertion / extraction prevents structural changes in the cathode material during use, maintaining structural integrity and ensuring the lifespan of the cathode material. Furthermore, when the cathode material's coating is a fluorine-containing mineral material, the fluorine-containing coating preferentially decomposes during the first charge-discharge process, forming a solid electrolyte interface film on the cathode material surface. This effectively prevents organic solvents in the electrolyte from penetrating into the core of the cathode material, reducing side reactions at the "electrolyte-cathode material" interface, improving the cathode material's stability and related electrical properties, and extending its lifespan.

[0034] According to some embodiments of the present invention, the lithium nickel cobalt manganese oxide material further includes secondary lithium nickel cobalt manganese oxide particles.

[0035] Secondary particles are larger particles formed by the aggregation of primary particles through agglomeration, sintering, or other physicochemical processes. Primary particles refer to the smallest, single particle units formed during the initial synthesis or preparation of the material, while secondary particles are more macroscopic particle structures formed by the further combination of these primary particles. Secondary particles typically have a porous structure with pores of varying sizes inside. These pores are formed by the gaps between primary particles, and the size and distribution of these pores have a significant impact on the material's performance. For example, in battery electrode materials, an appropriate pore structure can provide ion transport channels, which is beneficial for electrolyte penetration and lithium-ion diffusion. By controlling the size, morphology, and pore structure of secondary particles, the electrochemical performance of the cathode material can be improved, thereby increasing the battery's specific capacity, improving cycle stability, and rate performance. It should be noted that lithium nickel cobalt manganese oxide materials can be composed of multiple lithium nickel cobalt manganese oxide secondary particles, or multiple lithium nickel cobalt manganese oxide secondary particles and multiple lithium nickel cobalt manganese oxide primary particles, or a coating material can be directly coated onto the surface of the primary particles to form the cathode material.

[0036] According to some embodiments of the present invention, the fluorine-containing mineral material also contains sodium and / or lithium.

[0037] It is understandable that sodium (Na) in mineral materials + Lithium (Li) + The presence of cations such as sodium ions can balance the negative charge of mineral materials and influence the interlayer hydration state. The hydration layer of sodium ions occupies the interlayer space, reducing gas diffusion channels and effectively inhibiting the degradation of the cathode material during use. This enables ultra-stable lithium-ion storage and long-term chemical stability in air exposure, providing multiple protection mechanisms and simultaneously improving the mechanical strength, thermal stability, and chemical inertness of the cathode material. Furthermore, the presence of fluorine in the coating material enhances the surface hydrophobicity of the cathode material, reducing the adsorption and permeation of polar gases (such as water vapor), allowing the cathode material of this invention to maintain stable electrochemical performance even after prolonged exposure to ambient air.

[0038] For example, fluorine-containing mineral materials can be classified as sodium fluoride lithium mineral materials. Sodium fluoride lithium mineral materials are a class of mineral materials containing sodium, fluorine, and lithium ions, or mineral materials modified by elements such as sodium, fluorine, and lithium. These materials possess a stable crystal structure, and when coated on the core surface, they provide physical support, mitigating volume changes during charging and discharging, reducing structural damage and particle breakage, thereby improving the structural stability of the cathode material and extending the battery's cycle life. Furthermore, a multifunctional cathode-electrolyte interface (CEI) layer can be formed between the cathode material and the electrolyte, reducing interfacial resistance and improving lithium-ion transport efficiency at the interface, making the charging and discharging process more efficient. Simultaneously, this coating layer prevents direct contact between the electrolyte and the core, reducing side reactions and improving battery safety and stability. Sodium fluoride lithium mineral materials also exhibit good chemical stability, resisting electrolyte corrosion and preventing the active materials in the cathode material from dissolving into the electrolyte, thus improving the chemical stability of the cathode material and maintaining battery performance. For example, fluorine-containing mineral materials contain sodium and / or lithium, which gives the material itself high ionic conductivity. The coating layer can form a fast lithium-ion transport channel on the core surface, promoting lithium-ion migration and improving the battery's charge and discharge performance, especially under high-rate charge and discharge conditions, it can effectively improve the battery's rate performance.

[0039] According to some embodiments of the present invention, the fluorine-containing mineral material is a fluorine-modified mineral material, including at least one of montmorillonite, hydrotalcite, hexagonal boron nitride, halloysite, and kaolinite; preferably, the mineral material includes montmorillonite.

[0040] For example, montmorillonite can form chemical bonds with the core through hydrogen bonding or coordination, preventing the coating layer from peeling off and extending the lifespan of the cathode material. Furthermore, montmorillonite layers can exchange cations (such as Na+). + Ca 2+ ) adsorbs impurity ions (such as Fe) in the electrolyte through ion exchange. 3+ Cu 2+ This reduces side reactions and optimizes interfacial charge distribution, thereby effectively extending the lifespan of cathode materials. Furthermore, montmorillonite is abundant and can be used as a coating material without complex modification, effectively reducing the production difficulty and cost of cathode materials and enhancing their market competitiveness.

[0041] Hydrotalcite possesses hydroxyl groups (-OH) that can form hydrogen bonds with Li-O bonds on the core surface, while interlayer cations (such as Mg) can also form hydrogen bonds. 2+Hydrotalcite can form ionic bonds with defect sites on the surface of active particles in the core material, thereby enhancing the interfacial bonding strength between the core and the coating layer, preventing the coating layer from detaching after multiple cycles, and ensuring service life. Furthermore, the layered structure of hydrotalcite possesses a certain degree of flexibility, which can buffer the volume expansion and contraction caused by ion insertion / extraction during the charging and discharging process of cathode materials (such as ternary materials NCM / NCA and lithium iron phosphate LFP), reducing particle breakage and pulverization, thus maintaining the integrity of the cathode material structure and extending cycle life. In addition, hydrotalcite precursors can be uniformly coated onto the surface of the core material using solution methods (such as sol-gel and impregnation), making them suitable for existing battery production processes, helping to reduce production costs and improve production efficiency.

[0042] Hexagonal boron nitride (BON) is chemically inert, making it resistant to oxidation and decomposition under high voltage. This effectively prevents direct contact between the electrolyte and the core, inhibiting core degradation during use and ensuring a longer lifespan. Furthermore, BON exhibits ultra-high resistivity. When used as a coating layer for the positive electrode material, BON effectively prevents internal short circuits, enhancing battery safety. Additionally, BON's inertness to strongly oxidizing electrolytes prevents electrolyte penetration into the positive electrode material, reducing core dissolution and extending cycle life. Moreover, BON's flexible layered structure, combined with the physical bonding effect of the coating layer, enhances the mechanical strength of the positive electrode material, reducing the risk of pulverization during cycling and further extending its lifespan.

[0043] The difference in surface charge between halloysite and its inner surface (negative charge on the outer surface, positive charge on the inner surface) allows for the adsorption of lithium ions from the electrolyte via ion exchange, forming Li. + Enrichment layer. Simultaneously, surface hydroxyl groups (-OH) form hydrogen bonds with the Li-O bonds on the cathode material surface, enhancing interfacial adhesion and effectively preventing the coating layer from detaching during cycling, thus improving the structural stability of the cathode material and extending its service life. Furthermore, the tubular structure of halloysite provides a directional transport path for lithium ions, significantly shortening the Li-O bond lifespan. + This increases the migration distance, thereby improving the overall performance of the battery and expanding its application scenarios.

[0044] Kaolinite's layered structure possesses natural mechanical rigidity, forming a physical barrier on the core surface to buffer stress caused by volume expansion / contraction during charging and discharging, reducing core crack formation and extending the lifespan of the cathode material. Furthermore, the hydroxyl groups (-OH) on the kaolinite surface form chemical bonds with metal ions on the core surface through hydrogen bonding or coordination, ensuring a tight bond between the coating layer and the substrate. This effectively reduces the risk of coating layer detachment, thereby extending the lifespan of the cathode material.

[0045] Preferably, the mineral material includes montmorillonite. For example, sodium (Na₂O₃) + Lithium (Li)+ Cations such as sodium ions can balance the negative charge of the montmorillonite layers, affecting the hydration state between the layered montmorillonite layers. The hydrated layer of sodium ions occupies the interlayer space, reducing gas diffusion channels and effectively inhibiting core degradation during use, thus achieving ultra-stable lithium-ion storage and long-term chemical stability in air exposure. For example, when the coating material is sodium fluoride lithium montmorillonite nanosheets, the water content in the cathode material is significantly lower than that of sodium fluoride lithium hydrotalcite nanosheets or sodium fluoride lithium hexagonal boron nitride nanosheets, thereby effectively reducing polarization during use, improving the electrical performance of the cathode material, and extending its service life.

[0046] According to some embodiments of the present invention, the structure of the mineral material is a nanosheet structure. Specifically, a nanosheet refers to a two-dimensional inorganic nanomaterial whose external dimension in one dimension is at the nanoscale (1-100 nanometers), and whose external dimensions in the other two dimensions are significantly larger than the smallest nano-sized object. It should be noted that "smallest dimension" refers to the thickness of the nanosheet, i.e., the dimension in the z-axis direction, while "significantly larger than" means that the dimensions in the other two dimensions are three times or more larger than the "smallest dimension".

[0047] For example, the formation mechanism of sodium fluorine lithium montmorillonite with nanosheet structure is as follows: Sodium fluorine lithium montmorillonite (Hec, chemical formula: Na) 0.5 Mg 2.5 Li 0.5 Si4O 10 F2) Allows for a one-dimensional dissolution process through spontaneous thermodynamics, involving interlayer dissociation (Note: refers to the directional dissolution behavior of layered mineral materials along the c-axis (i.e., perpendicular to the bottom surface of the crystal) (also known as osmotic swelling: the osmotic swelling mechanism originates from interlayer cations (Na)). + ) with H in the solution + Driven by a concentration gradient, the sodium fluoride montmorillonite is exfoliated into nanosheets with a thickness of 1 nm. This exfoliation mechanism requires no additional mechanical or thermal energy; simply immersing the sodium fluoride montmorillonite in deionized water triggers its complete dissociation into negatively charged monolayer nanosheets. In other words, during the reaction process after adding a sodium fluoride montmorillonite solution to the first suspension, the sodium fluoride montmorillonite spontaneously exfoliates into nanosheets, such as sodium fluoride montmorillonite nanosheets, to uniformly coat the surface of the cathode material, forming a coating layer. Therefore, when the mineral material has a nanosheet structure, it is beneficial to improve the uniformity of the coating layer on the core surface, thereby forming a uniform and complete protective layer on the core surface to inhibit core degradation during use and ensure the stability of the electrical performance of the cathode material during long-term use.

[0048] When lithium sodium fluoride montmorillonite is exfoliated into lithium sodium fluoride montmorillonite nanosheets, these nanosheets possess an ultrathin two-dimensional structure, typically ranging from a few nanometers to tens of nanometers in thickness, with lateral dimensions reaching hundreds of nanometers or even micrometers. Consequently, the coating layer prepared using lithium sodium fluoride montmorillonite nanosheets is an ultrathin and uniformly coated layer structure; for example, the formed coating layer can be a continuous coating with a nanometer-thickness (approximately 1 nm), exhibiting both thinness and uniformity. Furthermore, the variety of lithium sodium fluoride mineral materials is abundant, thus enriching the raw materials for cathode material preparation. This allows for more flexible selection of raw materials based on specific application requirements, while also ensuring the lifespan of the cathode material. For example, lithium sodium fluoride hydrotalcite nanosheets, lithium sodium fluoride hexagonal boron nitride nanosheets, lithium sodium fluoride halloysite nanosheets, and lithium sodium fluoride kaolinite nanosheets refer to the nanosheet structures of lithium sodium fluoride hydrotalcite, lithium sodium fluoride hexagonal boron nitride, lithium sodium fluoride halloysite, and lithium sodium fluoride kaolinite, respectively. It should be noted that when the mineral material is hydrotalcite, hexagonal boron nitride, halloysite, and kaolinite, the mechanism of action is similar to that of sodium fluorine lithium montmorillonite nanosheets. The following text will use sodium fluorine lithium montmorillonite nanosheets as an example for detailed explanation.

[0049] In addition, when nanosheet-structured mineral materials are used as coating layers for cathode materials, they have a large specific surface area, which can provide a good physical barrier effect. This can effectively prevent direct contact between the electrolyte and the core, reduce the degradation of the core during use, and extend its service life.

[0050] According to some embodiments of the present invention, the coating layer accounts for x% of the mass of the positive electrode material, wherein 0.05wt%≤x≤3.5wt%, preferably 0.07wt%≤x≤3wt%; and / or, the thickness of the coating layer is W, wherein W≤7.5nm, preferably 0.1nm≤W≤5nm.

[0051] In one specific embodiment, the coating layer accounts for 0.05wt%-3.5wt% of the mass percentage of the cathode material.

[0052] For example, the coating layer accounts for 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 2.0 wt%, 3.0 wt%, 3.1 wt%, 3.2 wt%, 3.3 wt%, 3.4 wt%, or 3.5 wt%, or a range of two of these values, of the mass percentage of the cathode material.

[0053] When the mass percentage (x) of the coating layer in the cathode material is greater than or equal to 0.05 wt%, the resulting coating layer has a certain thickness, which helps improve the uniformity of the coating layer on the core surface, thereby avoiding coating layer cracking caused by local stress concentration and extending cycle life. Furthermore, it also helps shorten the ion diffusion path, reduce interfacial impedance, and optimize the battery's cycle performance. When the mass percentage (x) of the coating layer in the cathode material is less than or equal to 3.5 wt%, the resulting coating layer has a moderate thickness, which helps form a complete physical barrier on the core surface, effectively inhibiting core decomposition during use and thus extending battery life. By controlling the mass percentage (x) of the coating layer in the cathode material within the range of 0.05 wt% to 3.5 wt%, a reasonable mass percentage setting of the coating layer in the cathode material is beneficial for forming a moderately thick, uniform, and continuous coating layer on the core surface, thereby effectively preventing core degradation and extending battery life.

[0054] In a preferred embodiment, the coating layer accounts for 0.07wt%-3wt% of the mass percentage of the cathode material.

[0055] For example, the coating layer accounts for 0.07 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 2.0 wt%, or 3.0 wt%, or a range of two of these values, of the cathode material.

[0056] When the mass percentage (x) of the coating layer in the cathode material is greater than or equal to 0.07 wt%, the resulting coating layer has a certain thickness, which is beneficial for improving the consistency of the coating layer material, reducing material agglomeration, and thus further improving the uniformity of the coating layer on the core surface. In addition, it also helps to shorten the ion diffusion path, reduce interfacial impedance, and further optimize the cycle performance of the battery. When the mass percentage (x) of the coating layer in the cathode material is less than or equal to 3 wt%, the resulting coating layer has a moderate thickness, which is beneficial for forming a complete physical barrier on the core surface, thereby effectively inhibiting the erosion of the cathode material by the electrolyte under high voltage, reducing core decomposition, and thus ensuring the service life of the cathode material. By controlling the mass percentage (x) of the coating layer in the cathode material within the range of 0.07 wt%-3 wt%, the range of the mass percentage of the coating layer in the cathode material is further narrowed, which is beneficial for forming a coating layer of moderate thickness and more uniform and continuous surface on the core, thereby further improving the structural stability of the cathode material and reducing the possibility of coating layer peeling or detachment during use.

[0057] In one specific embodiment, the thickness W of the coating layer is ≤7.5 nm.

[0058] For example, the thickness of the coating layer is 0.1nm, 0.2nm, 0.3nm, 0.4nm, 0.5nm, 0.6nm, 0.7nm, 0.8nm, 0.9nm, 1.0nm, 2.0nm, 3.0nm, 4.0nm, 5.0nm, 6.0nm, 7.0nm, or 7.5nm, or a range of two of these values.

[0059] When the thickness W of the coating layer is less than or equal to 7.5 nm, the reasonable thickness range of the coating layer can block the interfacial side reactions between the core active material and the electrolyte and improve the charge and discharge capacity of the battery, thereby effectively improving the electrical performance of the cathode material and expanding its application scenarios. Furthermore, it facilitates the processing and preparation of the cathode material, reduces production costs, and improves production efficiency.

[0060] In a preferred embodiment, the thickness W of the coating layer is 0.1 nm to 5 nm.

[0061] For example, the thickness of the coating layer is 0.1 nm, 0.2 nm, 0.3 nm, 0.4 nm, 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, 1.0 nm, 2.0 nm, 3.0 nm, 4.0 nm, or 5.0 nm, or a range of two of these values. When the coating layer thickness is greater than or equal to 0.1 nm, a thin and uniform coating layer can be formed on the core surface, which is beneficial to improving the battery's charge and discharge capacity and optimizing battery cycle stability. Furthermore, it is also beneficial to the lightweight development of the battery. When the coating layer thickness is less than or equal to 5 nm, it is beneficial to block interfacial side reactions between the core active material and the electrolyte, reduce the gas generation rate during battery cycling, and improve battery safety. When the coating layer thickness W is in the range of 0.1 nm to 5 nm, the thickness range of the coating layer is further reduced, which can effectively block interfacial side reactions between the core active material and the electrolyte and further improve the battery's charge and discharge capacity, thereby resulting in better electrical performance of the cathode material.

[0062] According to some embodiments of the present invention, the particle size Dv50 of the positive electrode material is ≤11μm, preferably 1μm≤Dv50≤10μm; and / or, the specific surface area of ​​the positive electrode material is M, wherein M≤3.5m². 2 / g, preferably 1m 2 / g≤M≤3m 2 / g.

[0063] In one specific embodiment, the particle size Dv50 of the cathode material is ≤11μm.

[0064] For example, the particle size of the cathode material is 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm or 11 μm, or a range of two of these values.

[0065] In this invention, Dv50 is the median particle size based on particle volume distribution, referring to the particle diameter corresponding to a cumulative volume percentage of 50% in the particle size distribution curve. When the particle size of the core material is less than or equal to 11 μm, the particle size setting of the cathode material is reasonable, giving the cathode material a suitable specific surface area, which is beneficial for the insertion and extraction of lithium ions during charging and discharging, improving the activity of the electrode reaction, thereby enhancing the charge and discharge capacity and rate performance of the battery, and effectively improving the electrical performance of the cathode material.

[0066] In a preferred embodiment, the particle size Dv50 of the cathode material is 1μm-10μm.

[0067] For example, the particle size of the cathode material can be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, or 10 μm, or a range of two of these values. For instance, when the particle size Dv50 of the cathode material is greater than or equal to 1 μm, the specific surface area of ​​the core can be increased, resulting in a greater number of reaction interfaces between the active material and the electrolyte, thereby effectively increasing the battery's charge and discharge capacity. Furthermore, it can reduce the volume expansion stress of the cathode material during charge and discharge, reducing the risk of cracking and extending the battery's cycle life. When the particle size Dv50 of the cathode material is less than or equal to 10 μm, the cathode material has better flowability, is less prone to agglomeration, and can reduce the amount of binder used, thus reducing production difficulty. When the particle size of the core material is in the range of 1μm-10μm, the particle size range of the cathode material is further reduced, which makes the cathode material have a more suitable specific surface area, which is conducive to the insertion and extraction of lithium ions during the charging and discharging process, further improving the activity of the electrode reaction, thereby improving the charge and discharge capacity and rate performance of the battery, and making the electrical performance of the cathode material better.

[0068] In one specific embodiment, the specific surface area M of the positive electrode material is ≤3.5m². 2 / g.

[0069] For example, the specific surface area of ​​the positive electrode material is 1m². 2 / g, 1.5m 2 / g、2m 2 / g, 2.5m 2 / g、3m2 / g or 3.5m 2 / g, or a range consisting of two of the values.

[0070] For example, the specific surface area of ​​a cathode material refers to the surface area per unit mass of cathode material, and is an important indicator for evaluating the microstructure and performance of cathode materials. When the specific surface area of ​​a cathode material is less than or equal to 3.5 m², it is considered a specific surface area. 2 At a specific surface area of ​​ / g, the cathode material exhibits a moderate specific surface area. This allows for sufficient contact and reaction between the active material and the electrolyte within the cathode material, while reducing the diffusion resistance of lithium ions, thereby ensuring the overall performance and capacity utilization of the battery. Furthermore, it improves the structural stability of the cathode material and extends its lifespan. For example, the particle size of secondary lithium nickel cobalt manganese oxide particles affects the specific surface area of ​​the cathode material. By controlling the particle size of these secondary particles, the specific surface area of ​​the cathode material can be controllably adjusted, thus expanding the application range of cathode materials.

[0071] In a preferred embodiment, the specific surface area M of the positive electrode material is 1m². 2 / g-3m 2 / g.

[0072] For example, the specific surface area of ​​the positive electrode material is 1m². 2 / g, 1.5m 2 / g、2m 2 / g, 2.5m 2 / g or 3m 2 / g, or a range consisting of two of the values.

[0073] When the specific surface area M of the positive electrode material is greater than or equal to 1m 2 At a specific surface area M of 3m² / g, it is beneficial to reduce the contact interface between the cathode material and the electrolyte, thereby effectively reducing the decomposition of the cathode material and extending its service life. Furthermore, it can suppress interfacial side reactions and improve the cycle stability of the cathode material. 2 At a specific surface area of ​​1 m² / g, it is beneficial to shorten the lithium-ion diffusion path and reduce charge transfer impedance, thereby improving the battery charge and discharge capacity. Furthermore, it also helps to improve the uniformity and continuity of the coating layer, effectively inhibiting core degradation and extending the lifespan of the cathode material. 2 / g-3m 2 Within the range of / g, the specific surface area range of the cathode material is further reduced, which can further reduce the diffusion resistance of lithium ions while ensuring that the active material in the cathode material and the electrolyte are in full contact and react, thereby effectively improving the overall performance and capacity utilization of the battery.

[0074] A method for preparing a cathode material according to a second aspect of the present invention includes the following steps: The cathode material is obtained by mixing the core with fluorine-containing mineral materials.

[0075] Specifically, the core can be dispersed in a solvent to obtain a uniformly dispersed first suspension. For example, a uniformly dispersed first suspension can be obtained by stirring, sonication, or adding a dispersant. Then, a binder solution is added to the first suspension. After the reaction is complete, the mixture is washed, purified, and re-dispersed. A fluorine-containing mineral material dispersion is then added dropwise to the suspension while the mixture is continuously stirred to prepare the cathode material. This results in a highly uniform first suspension, ensuring the core is evenly distributed on the current collector, forming a coating of uniform thickness, thus guaranteeing the lifespan of the cathode material. It should be noted that the mixing of the core and the fluorine-containing mineral material can also be a direct mixing of the core and the fluorine-containing mineral material powder (i.e., dry mixing). The mixing method can be determined based on the specific circumstances.

[0076] For example, refer to Figure 1 SEM images of the cathode material in Example 1 show that the surface of the lithium nickel cobalt manganese oxide secondary particles is completely coated with sodium fluorine lithium montmorillonite nanosheets. The nanoscale coating layer has good flexibility and forms a continuous film on the surface of the lithium nickel cobalt manganese oxide secondary particles through partial overlap. After calcination, the elemental distribution of Si and Mg (the main components of sodium fluorine lithium montmorillonite nanosheets) on the surface of the cathode material shows a uniform coverage characteristic, further confirming that a complete and continuous coating layer has been formed on the surface of the lithium nickel cobalt manganese oxide secondary particles.

[0077] For example, the thickness of the coating layer can be determined through CP-SEM (Cyclic Optical Sequencing Electron Microscopy), enabling controllable coating and improving the lifespan of the cathode material. Furthermore, TGA (Thermogravimetric Analysis) can determine the percentage of the cathode material's mass in the coating layer. By combining the aforementioned physical property test results with the electrical performance test results, the influence of coating layer thickness and its percentage on the cathode material's electrical performance can be determined, leading to optimal cathode material preparation conditions that meet the application requirements of cathode materials in various scenarios.

[0078] It should be noted that in the actual preparation process, the thickness of the coating layer will also be affected by other factors, such as coating process, temperature, time, solution concentration, etc. The preparation conditions can be adjusted according to the actual situation to achieve controllable coating of the coating layer. The above reaction conditions are not specifically limited here.

[0079] This configuration creates a uniform coating layer on the core surface, ensuring the structural stability of the cathode material and improving its operational stability and related electrical properties. Furthermore, it yields a cathode material with a high-coverage three-dimensional coating structure, effectively improving the uniformity of the coating layer, reducing the possibility of coating layer detachment during use, ensuring the structural stability of the cathode material, and effectively extending its service life.

[0080] For example, the particle size of the cathode material can be determined by PSA (Particle Size Analysis), enabling precise control of the particle size and allowing selection of cathode materials with different particle sizes based on actual application requirements. Furthermore, the specific surface area of ​​the cathode material is related to its particle size and can be determined by BET (Body Equivalent Test). For instance, the particle size and specific surface area of ​​the cathode material can be controlled by adjusting the ball milling time and speed during the preparation process. Therefore, by adjusting the ball milling time and speed, the particle size and specific surface area of ​​the cathode material can be controlled, simplifying the preparation process, reducing the difficulty of cathode material preparation, and improving preparation efficiency. It should be noted that the CP-SEM, TGA, PSA, and BET tests mentioned above are all industry standard testing methods; specific operating steps are detailed in the test results of Examples 1-12 below.

[0081] Compared to the coating layers in related technologies, the coating layer in this application is thin and uniform. Utilizing the high aspect ratio (≈10,000) and excellent toughness of sodium fluorine lithium montmorillonite nanosheets, a high-coverage three-dimensional coating structure of lithium nickel cobalt manganese oxide secondary particles is achieved, fully encapsulating the core surface. This effectively improves the mechanical strength, thermal stability, and chemical inertness of the cathode material, enabling ultra-stable lithium-ion storage and long-term chemical stability under air exposure. Furthermore, the coating layer effectively suppresses phase transitions and degradation of the lithium nickel cobalt manganese oxide material and simultaneously forms a multifunctional CEI layer between the cathode material and the electrolyte, reducing interfacial resistance and improving lithium-ion transport efficiency at the interface, thus making the charging and discharging process more efficient.

[0082] Furthermore, the above materials are subjected to static sedimentation, washing to remove impurities, and drying in sequence to obtain a cathode material with a cathode material-coating layer structure. Therefore, the preparation method is simple, highly operable, relatively simple and reliable, easy to implement, and has high production efficiency.

[0083] For example, an aqueous wet coating process can be used to self-assemble the coating layer onto the core surface, thereby forming a core-coating structure cathode material. The aqueous wet coating process is a technique for coating a material surface, using water as a solvent or dispersion medium to formulate the coating material into an aqueous solution or emulsion. The coating material is uniformly coated onto the core surface using methods such as dip coating, spray coating, or flow coating. After drying and curing, a strong coating layer of fluorine-containing mineral material is formed on the core surface.

[0084] According to some embodiments of the present invention, mixing the core and the fluorine-containing mineral material specifically includes: The core, fluorine-containing mineral material, and solvent are mixed to obtain a mixed solution, which is then dried.

[0085] For example, in this application, the core and the fluorine-containing mineral material are mixed using a wet mixing method. The core and the fluorine-containing mineral material are separately and uniformly dispersed in a solvent. Then, the fluorine-containing mineral material dispersion is added dropwise to the core dispersion while continuously stirring and reacting. The mixed solution is then further dried to obtain the cathode material. Therefore, by using a wet mixing method to react the core and the fluorine-containing mineral material, the uniformity of the fluorine-containing mineral material coating can be effectively improved, resulting in a cathode material with a high coverage three-dimensional coating structure. This prevents partial peeling of the coating layer during use, ensures the structural integrity of the cathode material, and extends its service life.

[0086] In one specific implementation, reference is made to... Figure 2 When the coating layer accounts for 1.5 wt% of the cathode material and its thickness is 3.3 nm, the cathode material exposed to air for fifteen days can achieve a charging capacity of 172.1 mAh / g at 0.1C and a discharging capacity of 163.8 mAh / g at 0.1C, meaning that the first-charge efficiency (the ratio of the first discharge capacity to the first charge capacity) at room temperature can reach 95.18%. Therefore, the cathode material of this application still exhibits good charge-discharge capacity after fifteen days of exposure to air, demonstrating excellent chemical stability and good overall electrical performance.

[0087] According to some embodiments of the present invention, the mixed solution further includes a binder, which includes polyethyleneimine and / or polyallylamine.

[0088] For example, to achieve stable coating on the core surface, a binder (such as a cationic polyelectrolyte (PEI)) can be added to the first suspension under vigorous stirring to adjust the surface charge value of the lithium nickel cobalt manganese oxide. For instance, the surface charge value of the lithium nickel cobalt manganese oxide can be changed from negative to positive, allowing the lithium nickel cobalt manganese oxide material to form an interaction force with the negatively charged coating layer. This improves the structural stability of the core and promotes the uniformity of the coating layer on the core surface, resulting in a thin and uniform coating layer. Furthermore, Coulomb attraction ensures the uniform coating of the nanosheets on the core surface.

[0089] Furthermore, centrifugation and washing, such as three water washes, are used to remove unreacted free binder (i.e., binder not bound to the positive electrode material), thus removing excess binder. Therefore, by adding binder to the first suspension as described above, the coating stability and uniformity between the coating layer and the core are effectively improved, effectively reducing the possibility of coating layer peeling or breakage during use and extending its service life. In addition, the reaction process is simple and highly operable.

[0090] For example, when the binder solution is a polyethyleneimine solution (PEI solution) or a polyallylamine solution (PAA solution), both polyethyleneimine and polyallylamine solutions are cationic polyelectrolytes, which can change the surface charge of lithium nickel cobalt manganese oxide from negative (≈-25mV) to positive (≈30mV). This surface charge reversal allows the secondary particles of lithium nickel cobalt manganese oxide to adsorb negatively charged sodium fluoride lithium montmorillonite nanosheets (≈-20mV) through electrostatic interactions. Thus, there is an electrostatic attraction between the secondary particles of lithium nickel cobalt manganese oxide and the sodium fluoride lithium montmorillonite nanosheets, which can effectively improve the coating stability between the core and the coating layer, prevent the coating layer from detaching during cycling, and ensure the electrical performance of the core. Furthermore, the presence of Coulomb attraction between the core and the coating layer improves the uniformity of the coating layer on the core surface.

[0091] According to some embodiments of the present invention, the solvent includes deionized water, ethanol, ethylene glycol, isopropanol, N,N-dimethylformamide (DMF) or N-methyl-2-pyrrolidone (NMP).

[0092] For example, deionized water is a commonly used solvent in chemical reactions. It contains virtually no impurity ions, such as metal ions like calcium, magnesium, and iron, or anions like chloride and sulfate ions. This effectively avoids the influence of impurity ions on the reaction process, preventing the introduction of additional chemical reactions. This ensures the reaction proceeds along the intended path, improving its controllability and repeatability, and facilitating large-scale production and application. Furthermore, the preparation of deionized water is relatively simple and inexpensive, which helps reduce the production cost of cathode materials.

[0093] Ethanol is a common organic solvent with strong polarity and is miscible with water. Furthermore, ethanol can dissolve many polar and non-polar substances and has relatively low toxicity, which is beneficial for improving the environmental friendliness of the cathode material preparation process. In addition, ethanol's high volatility facilitates solvent removal through drying, thereby increasing the reaction rate. Moreover, ethanol has low production costs, which helps reduce the production cost of cathode materials.

[0094] Ethylene glycol's highly polar structure (containing two hydroxyl groups) gives it excellent solubility for transition metal salts, enabling the formation of a uniform primary suspension and preventing core composition deviations caused by uneven solute dispersion. Furthermore, ethylene glycol's high viscosity reduces particle agglomeration, promoting uniform dispersion of nanoscale cathode material particles and optimizing the material's specific surface area and ion diffusion pathways. In addition, ethylene glycol can reduce the hydrolysis tendency of metal ions, preventing the formation of hydroxide precipitates and maintaining the stability of the primary suspension.

[0095] Isopropanol has a lower viscosity than ethylene glycol, which can reduce the viscosity of the first suspension, promote mass transfer during stirring, and result in a more uniform distribution of metal ions, ultimately leading to a core material with a narrower particle size distribution. Furthermore, it can reduce local concentration differences during solution formation, inhibit particle agglomeration, improve the uniformity and stability of the core material, and extend the lifespan of the cathode material.

[0096] N,N-Dimethylformamide (DMF) is a highly polar solvent that can effectively dissolve polar core materials through dipole-dipole interactions, forming a uniform first suspension. This allows the active material particles to be fully encapsulated by the binder, improving the structural stability of the cathode material. Furthermore, its strong polarity enables DMF to encapsulate the core material through solvation, reducing interparticle van der Waals forces, minimizing agglomeration, and improving the uniformity of the first suspension.

[0097] N-Methyl-2-pyrrolidone (NMP) is a polar aprotic solvent that can effectively dissolve polar core materials and binders through dipole-dipole interactions, thereby forming a uniform and stable first suspension. This is beneficial for improving the uniformity and stability of the coating layer, thus improving the stability of the cathode material's performance and increasing the production yield of the cathode material.

[0098] According to some embodiments of the present invention, drying includes calcination to remove the binder connecting the cathode material and the coating layer. For example, in the preparation process of the cathode material, in order to achieve a stable and uniform coating on the core surface, a cationic polyelectrolyte (PEI) can be added as a binder. The binder connects the core and the coating layer to obtain a stable cathode material. By removing the binder connecting the core and the coating layer through calcination, the influence of the binder on the performance of the cathode material can be prevented, thereby ensuring the charge / discharge capacity and rate performance of the battery. Moreover, according to SEM images, the surface of the lithium nickel cobalt manganese oxide secondary particles is completely wrapped by sodium fluorine lithium montmorillonite nanosheets. The nanoscale clay sheets exhibit sufficient flexibility, forming a continuous coating on the surface of the lithium nickel cobalt manganese oxide secondary particles through partial overlap. That is, calcination to remove the binder connecting the core and the coating layer does not affect the performance of the cathode material.

[0099] According to some embodiments of the present invention, the calcination temperature is 450℃~600℃.

[0100] For example, the calcination temperature is 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, or 600°C, or a range of two of these values.

[0101] Optionally, lithium sodium fluoride montmorillonite is a fluorine-containing mineral material, meaning that the carbon-hydrogen bonds (CH) in the lithium sodium fluoride montmorillonite molecule are partially or completely replaced by carbon-fluorine bonds (CF), forming a CF-bonded framework. Due to the extremely high electronegativity and small atomic radius of fluorine, it can tightly encapsulate carbon atoms, forming a highly symmetrical and stable molecular structure, giving lithium sodium fluoride montmorillonite nanosheets thermal stability below 800℃. Furthermore, the sheet-like structure of lithium sodium fluoride montmorillonite nanosheets can alleviate thermal expansion stress caused by high temperatures through their own deformation, reducing the formation of macroscopic cracks, thus contributing to the thermal stability of lithium sodium fluoride montmorillonite nanosheets at high temperatures.

[0102] When the calcination temperature is set within the range of 450℃ to 600℃, the calcination temperature range is reasonable. After calcination, the sodium fluorine lithium montmorillonite nanosheets can still firmly coat the surface of the nickel-cobalt-manganese ternary cathode material. Moreover, the binder connecting the core and the coating layer can be effectively removed, thereby effectively preventing the binder from affecting the performance of the cathode material. Therefore, calcining the cathode material within the above-mentioned calcination temperature range has virtually no impact on its structural stability and can effectively remove the binder, extending the service life of the cathode material. It should be noted that the calcination temperature can also be set according to actual conditions.

[0103] In addition, the cathode material should be pretreated (e.g., dried) before calcination to remove moisture and other volatile impurities. The presence of moisture may affect the decomposition process of the binder between the core and the coating layer, and rapid evaporation of moisture at high temperatures may damage the cathode material structure. It should be noted that the heating rate during calcination should not be too rapid, and the holding time should be determined based on the properties of the cathode material and the binder content to minimize the impact of calcination on the cathode material's structure and performance.

[0104] According to some embodiments of the present invention, a method for preparing fluorine-containing mineral materials includes the following steps: Natural mineral materials are dispersed in a fluorine-containing solution, reacted, and then dried to obtain fluorine-containing mineral materials.

[0105] Specifically, natural mineral materials, or mineral materials obtained by ion exchange between natural mineral materials and salt solutions containing sodium and lithium ions, are dispersed in a fluorine-containing solution, reacted at a first temperature for a first time, cooled, washed until neutral, and then dried to obtain sodium fluoride lithium mineral materials.

[0106] For example, natural mineral materials such as montmorillonite can undergo cation exchange with salt solutions containing sodium ions (e.g., NaCl) and lithium ions (e.g., LiCl) to remove the original Ca2+ between the layers of the layered natural mineral material. 2+ Exchange for Na + and Li + The chemical reaction process equations are shown in equations (1) and (2) below. Furthermore, the mixed solution is centrifuged or filtered, and washed with deionized water to remove free Cl- from the solution. - Thus, sodium-lithium-based mineral materials were prepared.

[0107]

[0108] Equation (1)

[0109] Equation (2).

[0110] The sodium-lithium-based mineral material, after centrifugation, filtration, and washing, is uniformly dispersed in a solution containing fluoride ions (e.g., NaF). The reaction is carried out at a first temperature for a first time, causing F⁻ to replace the hydroxyl group (-OH) in the structure. The reaction solution is then cooled, washed until neutral, and dried to obtain the sodium fluoride-lithiated mineral material. For example, the above reaction process can be carried out in a hydrothermal reactor.

[0111] According to some embodiments of the present invention, the first temperature is T1, wherein 120℃≤T1≤180℃; and / or the first time is t, wherein 12h≤t≤48h.

[0112] In one specific embodiment, the first temperature T1 is 120℃-180℃.

[0113] For example, the first temperature is 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, or 180°C, or a range consisting of two of these values.

[0114] Therefore, a first temperature range of 120℃-180℃ is considered reasonable. Since the above reaction is endothermic, a first temperature within this range is beneficial for shifting the equilibrium towards the forward reaction, improving the exchange efficiency and increasing the calcium ion exchange rate. Furthermore, it can increase the ion exchange rate and shorten the time to reach reaction equilibrium, thereby improving production efficiency. In addition, it can prevent side reactions such as decomposition and oxidation of reactants or products at excessively high temperatures, avoiding material deterioration, preventing impurities in sodium-lithium based mineral materials, and improving product quality.

[0115] In one specific implementation, the first time t is 12h-48h.

[0116] For example, the first time is 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 22h, 24h, 26h, 28h, 30h, 32h, 34h, 36h, or 48h, or a range consisting of two of these values.

[0117] When the initial reaction time (t) is within the range of 12h-48h, a reasonable initial time range ensures the cation exchange reaction proceeds fully while reducing unreacted reactant residues, thus improving the purity of sodium-lithium-based mineral materials. Furthermore, it reduces side reactions caused by excessively long reaction times, further enhancing the quality of sodium-lithium-based mineral materials. In addition, it improves the controllability and reliability of the production process, reduces production costs, and enhances market competitiveness.

[0118] According to some embodiments of the present invention, ion exchange of natural mineral materials with a mixed solution specifically includes: Washing and removing impurities; After drying at a second temperature, the material is ground to obtain sodium-lithium-based mineral materials.

[0119] Specifically, after the above-mentioned natural mineral materials and the mixed solution undergo an ion exchange reaction, the resulting dispersion needs to be further washed to remove impurities. For example, deionized water can be used to remove free Cl- from the dispersion. - Remove to prevent free Cl -This can affect the structure and performance of the cathode material, or trigger side reactions during subsequent use, thus impacting the performance of the cathode material. Further, the sodium-lithium-based mineral material solution, after being washed, impurities removed, and the supernatant removed by centrifugation, is dried at a second temperature and then ground to obtain the sodium-lithium-based mineral material.

[0120] This setup allows for the preparation of sodium fluoride lithium mineral materials with high purity and low impurity content. When these materials are used as coatings for cathode materials, they effectively reduce the likelihood of degradation during use, extending the lifespan of the cathode material. Furthermore, the preparation method is simple, highly operable, relatively simple and reliable, easy to implement, and highly efficient, making it suitable for large-scale production and application.

[0121] According to some embodiments of the present invention, the second temperature is T2, wherein 80℃≤T2≤120℃.

[0122] In one specific embodiment, the second temperature T2 is 80℃-120℃.

[0123] For example, the second temperature is 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, or 120°C, or a range of two of these values.

[0124] With this setting, when the second temperature T2 is within the range of 80℃-120℃, the reasonable setting of the second temperature range allows for the slow and uniform evaporation of moisture in the sodium-lithium-based mineral material, avoiding structural stress caused by rapid water loss and thus maintaining the integrity of its layered structure and crystal morphology. Furthermore, it can remove free water and some adsorbed water from the sodium-lithium-based mineral material, initially optimizing its pore structure, which is beneficial for increasing its porosity and specific surface area, and facilitating subsequent adsorption and ion exchange processes of other substances. When sodium-lithium-based mineral materials are used as a coating layer for cathode materials, they can improve the uniformity and continuity of the coating layer, thereby achieving controllable coating layer thickness and extending the service life of the cathode material. It should be noted that different types of sodium-lithium-based mineral materials have different sensitivities to drying temperature due to differences in their chemical composition and structure. In practical applications, it is necessary to select an appropriate drying temperature based on the specific characteristics of the mineral material and application requirements to obtain ideal material performance; no specific limitation is made to the second temperature here.

[0125] For example, the method for preparing the cathode material according to the present invention includes the following steps: 1. Core pretreatment: The purchased lithium nickel cobalt manganese oxide sample was ball-milled.

[0126] 2. Primary Dispersion: Disperse the kernel from step 1 in deionized water (solvent) to obtain a first suspension. Add a binder solution to the first suspension and stir vigorously to obtain a first dispersion.

[0127] 3. Washing and purification: The dispersion obtained in step 2 is washed three times with deionized water to remove residual binder.

[0128] 4. Secondary dispersion: The product washed in step 3 is transferred to deionized water and redispersed to obtain a second suspension.

[0129] 5. Coating layer formation: Add sodium fluoride lithium mineral material dispersion dropwise to the second suspension in step 4, and stir continuously to obtain the third suspension.

[0130] 6. Post-treatment: Allow the third suspension from step 5 to settle, wash three times with deionized water to remove free components, and then perform gradient drying.

[0131] The electrode sheet according to a third aspect of the present invention includes a positive electrode material according to the first aspect of the present invention, or a positive electrode material prepared according to the preparation method of the second aspect of the present invention.

[0132] According to embodiments of the present invention, by employing the above-described positive electrode material, the performance of the electrode is further improved, effectively extending the cycle life of the electrode and reducing the cost of using the electrode.

[0133] A battery according to a fourth aspect embodiment of the present invention includes a positive electrode material according to the first aspect embodiment described above, or a positive electrode material prepared according to the preparation method of the second aspect embodiment described above, or an electrode sheet according to the third aspect embodiment described above.

[0134] According to embodiments of the present invention, by employing the above-described electrode, the polarization phenomenon of the battery during charging and discharging is effectively reduced, the energy efficiency of the battery is improved, the heat generated during battery use is reduced, and the battery life is extended.

[0135] A battery pack according to a fifth aspect embodiment of the present invention includes a positive electrode material according to the first aspect embodiment described above, or a positive electrode material prepared according to the preparation method of the second aspect embodiment described above, or an electrode sheet according to the third aspect embodiment described above, or at least two batteries according to the fourth aspect embodiment described above.

[0136] According to the battery pack of the present invention, by using the above-mentioned positive electrode material, electrode sheet or battery, the charging and discharging capacity of the battery pack is effectively improved, the charging cycle performance is improved, the application scenarios of the battery pack are expanded and the service life of the battery pack is extended.

[0137] An electrical device according to a sixth aspect embodiment of the present invention includes a positive electrode material according to the first aspect embodiment, or a positive electrode material prepared by the preparation method according to the second aspect embodiment, or an electrode sheet according to the third aspect embodiment, or a battery according to the fourth aspect embodiment, or a battery pack according to the fifth aspect embodiment.

[0138] According to embodiments of the present invention, by employing the aforementioned positive electrode material, electrode sheet, battery, or battery pack, the electrical equipment exhibits stable electrical performance during prolonged use, thereby extending its service life. For example, the electrical equipment may be an electric vehicle, a home energy storage system, or grid energy storage.

[0139] The embodiments of the present invention are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In addition, unless otherwise specified, all reagents used in the following embodiments are commercially available or can be synthesized according to the methods described herein or known to others. For reaction conditions not listed, they are also readily available to those skilled in the art.

[0140] The cathode material of the present invention will be described through exemplary embodiments and comparative examples. The following describes the performance tests of the cathode materials of the embodiments and comparative examples.

[0141] Example 1 The preparation method of the cathode material includes the following steps: 1. Core pretreatment: Pre-processing the purchased lithium nickel cobalt manganese oxide (chemical formula: LiNi) x Co y Mn 1-x-y O 2， Among them, the samples with 0 < x < 1, 0 < y < 1, and 0 < x + y < 1 were subjected to ball milling treatment, with a ball milling speed of 2000 rpm and a ball milling time of 3.5 h.

[0142] 2. Primary Dispersion: Disperse 500 mg of the kernel (secondary lithium nickel cobalt manganese oxide particles, with a particle size of 5.2 μm) from step 1 in 250 mL of solvent (deionized water) to obtain the first suspension. Add 18 mL of a 20% (w / w) binder solution (polyethyleneimine aqueous solution) to the first suspension and stir vigorously for 1 hour to obtain the first dispersion.

[0143] 3. Washing and purification: The first dispersion obtained in step 2 is washed three times with deionized water to remove residual binder (polyethyleneimine).

[0144] 4. Secondary dispersion: Transfer the washed product from step 3 to freshly prepared 250 mL of deionized water for redispersion to obtain a second suspension.

[0145] 5. Coating layer formation: Add 262 mL of sodium fluoride lithium montmorillonite dispersion with a mass fraction of 0.1% dropwise to the second suspension in step 4, and stir continuously for 1 hour to obtain the third suspension.

[0146] 6. Post-treatment: Allow the third suspension from step 5 to settle for 12 hours, then wash three times with deionized water to remove free components. Then perform gradient drying, first drying at 60℃ for 1 day, and then drying again at 120℃ for 1 day.

[0147] Example 2 The preparation method of Example 2 is basically the same as that of Example 1, except that in step 5, the volume of the sodium fluoride lithium montmorillonite dispersion is 9 mL.

[0148] Example 3 The preparation method of Example 3 is basically the same as that of Example 1, except that in step 5, the volume of the sodium fluoride lithium montmorillonite dispersion is 13 mL.

[0149] Example 4 The preparation method of Example 4 is basically the same as that of Example 1, except that in step 5, the volume of the sodium fluoride lithium montmorillonite dispersion is 525 mL.

[0150] Example 5 The preparation method of Example 5 is basically the same as that of Example 1, except that in step 5, the volume of the sodium fluoride lithium montmorillonite dispersion is 612 mL.

[0151] Example 6 The preparation method of Example 6 is basically the same as that of Example 1, except that in step 1, the ball milling speed is 3000 rpm and the ball milling time is 5 h.

[0152] Example 7 The preparation method of Example 7 is basically the same as that of Example 1, except that in step 1, the ball milling speed is 3000 rpm and the ball milling time is 4 h.

[0153] Example 8 The preparation method of Example 8 is basically the same as that of Example 1, except that in step 1, the ball milling speed is 2000 rpm and the ball milling time is 3 h.

[0154] Example 9 The preparation method of Example 9 is basically the same as that of Example 1, except that in step 1, the ball milling speed is 2000 rpm and the ball milling time is 2 h.

[0155] Example 10 The preparation method of Example 10 is basically the same as that of Example 1, except that in step 1, the ball milling speed is 1500 rpm and the ball milling time is 1 h.

[0156] Example 11 The preparation method of Example 11 is basically the same as that of Example 1, except that in step 1, the ball milling time is 4 hours, and in step 5, the structure of the coating material changes from a nanosheet structure to a block structure (i.e., the sodium fluorine lithium montmorillonite material is a non-nanosheet structure or has not been peeled off).

[0157] Example 12 The preparation method of Example 12 is basically the same as that of Example 1, except that in step 1, the ball milling speed is 2100 rpm, and in step 5, the structure of the coating material is changed from sodium fluorine lithium montmorillonite material to sodium fluorine lithium hydrotalcite material.

[0158] Example 13 The preparation method of Example 13 is basically the same as that of Example 1, except that in step 1, the ball milling speed is 2200 rpm, and in step 5, the structure of the coating material is changed from sodium fluorine lithium montmorillonite material to sodium fluorine lithium hexagonal boron nitride material.

[0159] Comparative Example 1 The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that the ball milling speed is 2000 rpm, the ball milling time is 3.5 h, and the coating layer formation process in step 5 is omitted (i.e., it only contains core material).

[0160] Comparative Example 2 The preparation method of Comparative Example 2 is basically the same as that of Example 1, except that the ball milling speed is 2000 rpm, the ball milling time is 3.5 h, and the structure of the coating material in step 5 is changed from sodium fluorine lithium montmorillonite material to Al2O3.

[0161] Physical property testing: 1. Cathode material coating thickness test (CP-SEM test, i.e., environmental scanning electron microscopy test, the test instrument is Hitachi SU8600): D1. Cut 2g vertically from the positive electrode material sample for testing, and grind and polish the cross-section of the cut sample to obtain the test sample. D2. Measure the thickness of the test sample from D1 using a scanning electron microscope. Take 20 measurements and average them. The test voltage is 5 kV and the current is 10 μA.

[0162] 2. Particle size testing of cathode materials (PSA test, i.e., functionalized particle test, using Malvern MS3000 instrument): 0.6 g of the test sample was mixed with 20 mL of 5 wt% sodium pyrophosphate solution and sonicated for 20 min to ensure thorough mixing before particle size analysis. Twenty data points were measured and the average value was taken. The refractive index was 1.74 and the absorbance was 1.0.

[0163] 3. Specific surface area of ​​the cathode material (BET test, testing instrument: McMurray 3Flex): A 3g test sample was baked and dried at 200℃ for 2 hours before testing. Twenty data points were measured and the average value was taken. The vacuum rate during the test was 0.67kPa / s, and the vacuum time was 10min.

[0164] 4. Test of the percentage of the coating layer in the mass of the cathode material (TGA test, i.e., thermogravimetric analysis, tested by Netzsch STA449F5 instrument, Germany): The coating layer is thermally decomposed. The mass percentage (x) of the coating layer in the cathode material satisfies: x = (m1 - m2) / m1 * 100%. Twenty data points were measured and the average value was taken. Here, m1 is the initial mass, and m2 is the mass of the coating layer after decomposition.

[0165] The test results are detailed in Table 1.

[0166] Table 1

[0167] Performance testing: 1. Moisture content test of cathode material D1. Take 2g of sample, record the initial mass m, and calibrate the Karl Fischer moisture analyzer with a standard aqueous solution (such as 10μg / μL water-methanol solution).

[0168] D2. Quickly transfer the weighed sample from D1 to the sealed sample cell of the Karl Fischer moisture analyzer and inject anhydrous methanol as a solvent, then start the automatic titration program. The instrument electrolyzes to produce iodine, which reacts with water. The current change is monitored in real time until the endpoint (when the water has completely reacted), at which point the instrument directly outputs the moisture content.

[0169] 2. Room temperature capacity and first-efficiency test of coin cells made using positive electrode materials. D1. Expose the positive electrode material to air for fifteen days; D2. Test conditions: In a 25℃ ambient cabinet, charge at 0.1C constant current and constant voltage to 4.2V, and discharge at 0.1C constant current to 3.0V.

[0170] 3. Room temperature cycling test of coin cells made using positive electrode materials D1. Expose the positive electrode material to air for fifteen days; D2. Test conditions: In a 25℃ ambient cabinet, 1C constant current charge and discharge for 200 cycles, voltage range is 3.0-4.2V.

[0171] Capacity retention rate over 200 cycles at room temperature = discharge capacity C over 200 cycles 200 Initial capacity C0 The test results are detailed in Table 2.

[0172] Table 2

[0173] As can be seen from the comparison of Examples 1-13 and the comparative example, under the condition that other conditions remain unchanged, when the coating material is sodium fluorine lithium montmorillonite nanosheets, the comprehensive performance of the cathode material is better than other forms of sodium fluorine lithium montmorillonite material, better than other coating materials or uncoated materials, effectively reducing the moisture content of the cathode material, improving the comprehensive electrical performance, and thus improving the comprehensive performance of the cathode material.

[0174] The cathode materials, preparation methods, electrode sheets, batteries, battery packs, and electrical devices and their operation according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0175] In the description of this invention, "a plurality of" means two or more.

[0176] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0177] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A positive electrode material, characterized in that, It includes a core and a coating layer covering at least a portion of the surface of the core, the core comprising lithium nickel cobalt manganese oxide, and the coating layer comprising a fluorine-containing mineral material.

2. The cathode material according to claim 1, characterized in that, The fluorine-containing mineral material also contains sodium and / or lithium.

3. The cathode material according to claim 1 or 2, characterized in that, The fluorine-containing mineral material is a fluorine-modified mineral material, and the mineral material includes at least one of montmorillonite, hydrotalcite, hexagonal boron nitride, halloysite, and kaolinite; preferably, the mineral material includes montmorillonite.

4. The cathode material according to any one of claims 1-3, characterized in that, The mineral material has a nanosheet structure.

5. The cathode material according to any one of claims 1-4, characterized in that, The coating layer comprises x% of the positive electrode material by mass, wherein 0.05wt%≤x≤3.5wt%, preferably 0.07wt%≤x≤3wt%; and / or The thickness of the coating layer is W, wherein W≤7.5nm, preferably 0.1nm≤W≤5nm.

6. The cathode material according to any one of claims 1-5, characterized in that, The particle size of the positive electrode material is Dv50≤11μm, preferably 1μm≤Dv50≤10μm; and / or The specific surface area of ​​the positive electrode material is M, where M ≤ 3.5m². 2 / g, preferably 1m 2 / g≤M≤3m 2 / g.

7. A method for preparing a cathode material according to any one of claims 1-6, characterized in that, Includes the following steps: The cathode material is obtained by mixing the core with fluorine-containing mineral materials.

8. The method for preparing the cathode material according to claim 7, characterized in that, The mixing of the core and fluorine-containing mineral materials specifically includes: The core, the fluorine-containing mineral material, and the solvent are mixed to obtain a mixed solution, which is then dried.

9. The method for preparing the cathode material according to claim 8, characterized in that, The mixed solution also includes a binder, which includes polyethyleneimine and / or polyallylamine.

10. The method for preparing the cathode material according to any one of claims 7-9, characterized in that, The preparation method of the fluorine-containing mineral material includes the following steps: The natural mineral material is dispersed in a fluorine-containing solution, and then dried after reaction to obtain the fluorine-containing mineral material.

11. An electrode sheet, characterized in that, It includes the cathode material according to any one of claims 1-6, or the cathode material prepared by the preparation method according to any one of claims 7-10.

12. A battery, characterized in that, It includes the positive electrode material according to any one of claims 1-6, or the positive electrode material prepared by the preparation method according to any one of claims 7-10, or the electrode sheet according to claim 11.

13. A battery pack, characterized in that, It includes the positive electrode material according to any one of claims 1-6, or the positive electrode material prepared by the preparation method according to any one of claims 7-10, or the electrode sheet according to claim 11, or at least two batteries according to claim 12.

14. An electrical appliance, characterized in that, It includes the positive electrode material according to any one of claims 1-6, or the positive electrode material prepared by the preparation method according to any one of claims 7-10, or the electrode sheet according to claim 11, or the battery according to claim 12, or the battery pack according to claim 13.

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