High-nickel positive electrode material and preparation method thereof

Abstract

The invention provides a high-nickel positive electrode material and a preparation method thereof, and relates to the technical field of battery materials. The high-nickel positive electrode material comprises a base material, a first coating layer and a second coating layer. According to the high-nickel positive electrode material, high capacity and lattice stability are guaranteed through a multi-element doped matrix, and surface modification is realized by using a double-layer coating structure constructed by a metal element R. Wherein the first coating layer utilizes an element R to consume residual alkali on the surface in situ to generate a fast ion conductor, and meanwhile, an electrochemical inert barrier is formed to inhibit an interface side reaction; a boron-containing component is introduced into the second coating layer to be synergistically complementary with the element R, so that the interface impedance is further reduced, the chemical stability is enhanced, and the rate capability, the cycle life and the safety of the material are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery materials, in particular to a high-nickel positive electrode material and a preparation method thereof. BACKGROUND

[0002] Under the promotion of global energy transformation, rechargeable energy storage devices represented by lithium ion batteries have become the core technology of electric vehicles, portable electronic products and large-scale energy storage systems. The energy density, cycle life, safety and cost of lithium ion batteries depend largely on the performance of their positive electrode materials. Therefore, developing new positive electrode materials with high energy density, high stability and low cost has always been the focus and frontier of research in this field.

[0003] Among the many positive electrode material systems, high-nickel layered positive electrode materials are considered one of the most promising choices for the next generation of high-energy-density lithium ion batteries because of their significantly higher reversible specific capacity than conventional materials and reduced dependence on rare cobalt resources. However, the commercial application of high-nickel materials still faces severe challenges. High nickel content leads to a decrease in the stability of the material's crystal structure, and the material's surface has extremely high chemical activity, which easily reacts with the electrolyte during charging and discharging cycles, leading to rapid capacity decay.

[0004] To solve the above problems, existing technical solutions usually use modification strategies such as element doping and surface coating. In addition, during the high-temperature sintering process of high-nickel materials, a certain amount of residual alkali such as lithium carbonate and lithium hydroxide will inevitably remain on the surface. These residual alkalis have strong hygroscopicity, not only causing the electrode slurry to gel during the preparation process, affecting the processing performance, but also decomposing to produce gas during battery cycling, leading to battery swelling and performance deterioration. Therefore, removing residual alkalis from the surface of the material is a necessary process in the preparation of high-nickel materials.

[0005] Currently, the most common means of removing residual alkalis is to use a water washing process. However, this process itself has serious defects. Traditional water washing methods can effectively reduce the residual alkali content on the surface of the material, but also cause irreversible damage to the surface structure of the high-nickel material. Contacting the high-activity surface with water can induce the leaching of lithium ions from the surface layer of the material, which not only destroys the layered structure of the material's surface, forming an electrochemically inert layer and increasing the interfacial impedance of lithium ion diffusion, but also leads to a significant decrease in the electrochemical performance of the material. Therefore, how to effectively remove harmful surface residual alkalis during the preparation of high-nickel positive electrode materials, while avoiding secondary damage to the surface structure of the material, achieving a balance between the stability of the material's bulk structure and the high activity of the surface interface, is a key technical problem that needs to be solved in the development of high-nickel positive electrode materials.

[0006] In view of the above, the present application is proposed. SUMMARY

[0007] The purpose of this invention is to provide a high-nickel cathode material and its preparation method. The high-nickel cathode material utilizes a multi-element doped matrix to ensure high capacity, and through the electrochemical inert barrier constructed by the in-situ consumption of residual alkali by metal element R and the synergistic double-layer coating of boron-containing components, the interfacial impedance is effectively reduced and side reactions are suppressed, significantly improving the rate performance, cycle life and safety of the material.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a high-nickel cathode material, the high-nickel cathode material comprising a matrix material, a first coating layer covering the matrix material, and a second coating layer covering the first coating layer; The chemical formula of the matrix material is LiNi. x M y M' z O2; Wherein, 0.80≤x≤0.98, 0<y≤0.20, 0<z≤0.02, and x+y+z=1; M represents at least two of Co, Mn, and Al, and M' represents at least three of Zr, Sr, Al, Sb, Y, and Ta; The first coating layer comprises a sinter derived from a first additive; the first additive comprises a compound containing element R; The second coating layer comprises a sinter derived from a second additive; the second additive comprises a compound containing element R and a boron-containing compound; Wherein, element R is a metal element that can react with residual lithium on the surface of the matrix material during sintering to form a lithium-metal composite oxide, and does not participate in redox reactions within the operating voltage range of the high-nickel cathode material during charging and discharging.

[0009] In some embodiments, the element R includes at least one selected from Al, Ti, Zr, Nb, W, Mg, Ta, and Y; preferably, the element R is Al and / or Ti; and / or, The compound containing element R is selected from at least one of oxides, hydroxides, and fluorides of element R.

[0010] In some embodiments, the first additive comprises at least one selected from Al₂O₃, LiAlO₂, and Al(OH)₃; and / or, The second additive contains H3BO3, and at least one of Al2O3, Al(OH)3 and AlF3.

[0011] In some embodiments, the matrix material has internal pores; or, the matrix material is a material with a loose porous structure and internal grains arranged radially divergently. Preferably, the cross-sectional porosity of the matrix material is 2% to 7%; Preferably, the cross-sectional porosity of the matrix material is 3% to 5%.

[0012] In some embodiments, M' in the general chemical formula represents Zr, Sr, and Al; and / or, The first additive contains Al2O3 and LiAlO2.

[0013] In some embodiments, the mass of Al in the first coating layer in the final product is 500 ppm to 3000 ppm; or, the mass of Al in the first coating layer in the final product is 1000 ppm to 2000 ppm; and / or, The mass of B in the second coating layer in the final product is 300 ppm to 3000 ppm; or, the mass of B in the second coating layer in the final product is 500 ppm to 1500 ppm; and / or, The mass of Al in the second coating layer in the final product is 0 ppm to 3000 ppm; or, the mass of Al in the second coating layer in the final product is 500 ppm to 1500 ppm.

[0014] Secondly, the present invention provides a method for preparing a high-nickel cathode material as described in any of the foregoing embodiments, comprising: The precursor, lithium source and third additive are mixed and sintered for the first time in an oxidizing atmosphere. The product from the first sintering is mixed with the first additive and then sintered a second time in an oxidizing atmosphere. The product from the secondary sintering was washed with water to obtain a washed product. The water-washed product is mixed with a second additive and sintered for the third time in an oxidizing atmosphere to obtain the high-nickel cathode material.

[0015] In some embodiments, the third additive comprises at least three of oxides or hydroxides of Zr, Sr, Al, Sb, Y, and Ta; and / or, The step of mixing the precursor, lithium source and third additive also includes adding a pore-forming agent; Preferably, the pore-forming agent comprises sulfate; Preferably, the pore-forming agent includes at least one of aluminum sulfate, magnesium sulfate, and lithium sulfate; Preferably, the pore-forming agent is a sulfate, and the amount of sulfate added is in the form of SO4. 2- The mass of the precursor is 0.05% to 2%; or, the pore-forming agent is a sulfate, and the amount of sulfate added is based on SO4.2- The mass of the quality meter is 0.2% to 1% of the mass of the precursor; and / or, The liquid-solid ratio of the water washing treatment is 0.4 to 1.0; and / or, The precursor includes Ni a M b (OH)2; wherein, 0.80 ≤ a ≤ 0.98, 0 < b ≤ 0.20, a + b = 1, and M represents at least two of Co, Mn, and Al.

[0016] In some embodiments, the first sintering includes a first heat preservation platform and a second heat preservation platform; Preferably, the temperature of the first heat preservation platform is 350°C to 650°C; and / or, the heat preservation duration of the first heat preservation platform is 2 hours to 6 hours; Preferably, the temperature of the second heat preservation platform is 680°C to 900°C; and / or, the heat preservation duration of the second heat preservation platform is 6 hours to 16 hours; and / or, The heat preservation temperature of the second sintering is 500°C to 700°C; and / or, The constant temperature duration of the second sintering is 5 hours to 10 hours; and / or, The heat preservation temperature of the third sintering is 200°C to 400°C; and / or, The constant temperature duration of the third sintering is 5 hours to 10 hours.

[0017] In the third aspect, the present invention provides an electrode, including the high-nickel cathode material according to any one of the foregoing embodiments; or, including the high-nickel cathode material prepared by the preparation method according to any one of the foregoing embodiments.

[0018] In the fourth aspect, the present invention provides a battery, including the electrode according to the foregoing embodiment.

[0019] In the fifth aspect, the present invention provides an electricity-related device, including the battery according to the foregoing embodiment.

[0020] The present invention provides a high-nickel cathode material and a preparation method thereof. Compared with the prior art, the high-nickel cathode material significantly improves the comprehensive electrochemical performance through specific matrix component design and double-layer coating structure. The matrix material adopts a high-nickel chemical system and introduces multiple specific elements for doping. While ensuring the high specific capacity advantage of the material, the stability of the bulk phase lattice structure is enhanced by multi-element doping.

[0021] The first coating layer utilizes the specific reactivity and electrochemical inertness of metal element R to achieve dual modification of the material surface. During sintering, metal element R actively reacts chemically with residual lithium on the substrate surface, generating lithium-metal composite oxide in situ. This process effectively consumes surface residual alkali that is detrimental to battery performance, improves the material's processing performance, and suppresses gas generation in subsequent batteries. Furthermore, the generated lithium-metal composite oxide, as a fast ion conductor, lowers the diffusion barrier of lithium ions at the interface, increasing the ion transport rate. In addition, since metal element R does not participate in redox reactions within the operating voltage range, the coating layer remains structurally stable during charge-discharge cycles, effectively isolating the electrolyte from the highly active substrate as a physical barrier, suppressing interfacial side reactions, and thus enhancing the material's cycle stability and safety.

[0022] The second coating layer, building upon the first, further introduces boron-containing compounds and compounds containing the metal element R, constructing a complementary outer protective structure. During processing, the boron-containing compounds can form boron-containing lithium compounds with excellent ionic conductivity, helping to further reduce battery interface impedance and improve discharge capacity. The metal element R in the second coating layer works synergistically with the boron-containing components to form a composite interface with both high ionic conductivity and high chemical stability on the outermost layer of the material. This inside-out double-layer coating design utilizes element R to achieve the conversion of surface residual alkali and structural strengthening, while combining the conductivity-enhancing properties of boron. This synergistically improves the rate performance, long cycle life, and thermal stability of the high-nickel material while ensuring its high energy density. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic flowchart illustrating the preparation method of the high-nickel cathode material in the embodiments of this application; Figure 2 This is a cross-sectional SEM image of the high-nickel cathode material obtained in Example 1; Figure 3 This is a cross-sectional SEM image of the high-nickel cathode material obtained in Example 3; Figure 4 Here is a cross-sectional SEM image of the high-nickel cathode material obtained in Comparative Example 5; Figure 5 The diagram shows the cycling results of the high-nickel cathode materials obtained in Example 1 and Comparative Example 1. Detailed Implementation

[0025] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0026] This application provides a high-nickel cathode material, including a matrix material, a first coating layer covering the matrix material, and a second coating layer covering the first coating layer; The aforementioned high-nickel cathode material is a composite material whose core feature is a precisely controlled multilayer coating structure. Its overall structure is a three-layer structure in space: (1) Matrix material (the innermost core); (2) First coating layer (wrapped on the substrate); (3) Second covering layer (wrapped on the first covering layer).

[0027] This "onion-like" layered structure is its fundamental structural feature.

[0028] The chemical formula of the matrix material is LiNi. x A y B z O2; where 0.80≤x≤0.98, 0<y≤0.20, 0<z≤0.02, and x+y+z=1; M represents at least two of Co, Mn, and Al, and M' represents at least three of Zr, Sr, Al, Sb, Y, and Ta.

[0029] As mentioned above, the matrix material is the main body and core of the material, serving as the functional entity for storing and releasing lithium ions. The general chemical formula of its components is defined as LiNi. x A y B z O2 is a lithium-nickel-based layered oxide.

[0030] The value of x is between 0.80 and 0.98, and this high proportion (≥0.80) determines that this is a "high nickel" material.

[0031] M represents at least two of Co (cobalt), Mn (manganese), and Al (aluminum). These are elements used to stabilize the structure.

[0032] M' represents at least three of Zr (zirconium), Sr (strontium), Al (aluminum), Sb (antimony), Y (yttrium), and Ta (tantalum). These are doping elements used to further optimize the properties of the matrix material.

[0033] The first coating layer comprises a sintered product derived from a first additive; the first additive includes a compound containing element R; the second coating layer comprises a sintered product derived from a second additive; the second additive includes a compound containing element R and a boron-containing compound; wherein, element R is a metallic element that can react with residual lithium on the surface of the substrate material during sintering to form a lithium-metal composite oxide, and does not participate in redox reactions within the operating voltage range of the high-nickel cathode material during charge and discharge.

[0034] The aforementioned first coating layer is the first "protective shell" covering the base material. It is defined as "sintered material derived from the first additive". "Sintered material" means that it is not simply a mixture of additive powders, but refers to the product of the additive after high-temperature treatment, that is, a new substance formed after reacting or undergoing a phase change with the material surface.

[0035] The aforementioned "compound containing element R" refers to the first additive used as a raw material, which must contain the metal element R (such as aluminum oxide Al2O3 as a carrier of R).

[0036] It should be noted that the first additive (containing element R) can chemically react with residual lithium (such as LiOH or Li2CO3) on the surface of the matrix during the sintering process to generate lithium-metal composite oxides (such as LiAlO2).

[0037] Harmful residual lithium on the material surface is consumed through chemical reactions, improving the material's processing performance (such as preventing slurry gelation). The resulting lithium-metal composite oxides (such as LiAlO2) are typically fast ion conductors, reducing the lithium-ion diffusion energy barrier at the interface and increasing the lithium-ion diffusion rate. Structural enhancement: Sintered materials can penetrate into the intergranular spaces, enhancing the overall structural strength and suppressing crystal cracking.

[0038] The aforementioned "second coating layer covering the first coating layer" refers to the outermost structure located outside the first coating layer, forming an "onion-like" structure of "matrix-first layer-second layer".

[0039] The second additive mentioned above is a composite system that includes both sources of element R (such as alumina) and sources of boron (such as boric acid H3BO3).

[0040] It should be noted that during sintering, the material melts and reacts with residual alkali to form lithium borate series compounds (which are also fast ion conductors). The element R compound acts as a physical protective barrier. The second coating layer utilizes a combination of "R element + boron," where R element primarily provides physical isolation, and boron primarily provides conductivity optimization.

[0041] Compared to single coating, the combination of R and B (boron) has a synergistic effect in suppressing side reactions, improving ion transport, and enhancing thermal stability. The fast ion conductor formed by the boron-containing component helps increase the initial discharge capacity and reduce battery impedance. The R-containing component effectively isolates the cathode material from the electrolyte, suppressing harmful side reactions.

[0042] The aforementioned phrase "able to react with residual lithium on the surface of the matrix material during sintering to form a lithium-metal composite oxide" defines the chemical activity of element R. This means that the element must possess the ability to "remove alkali," that is, it must be able to combine with lithium sources on the matrix surface (such as residual lithium hydroxide or lithium carbonate) at high temperatures to transform into stable lithium-containing compounds (e.g., Al₂O₃ + Li₂CO₃ → (high temperature) 2LiAlO₂ + CO₂↑).

[0043] The statement that "it does not participate in redox reactions within the operating voltage range of the high-nickel cathode material" defines the electrochemical stability of element R. This means that within the battery's operating range (e.g., 2.8V~4.3V), the valence state of element R remains constant (e.g., Al is always +3), unlike nickel and cobalt in the matrix, which undergo valence state changes to provide capacity.

[0044] The principle lies in utilizing the "inertness" of element R as a framework and its "lithophile" nature as a modifier. Since element R does not participate in redox reactions, the coating layer it forms is extremely stable in structure during charge-discharge cycles and will not detach due to volume changes or phase transitions, thus effectively stabilizing the material surface structure over a long period. Furthermore, the stable oxide layer acts as a physical barrier, reducing direct contact between the highly active, high-nickel substrate and the electrolyte, significantly suppressing the risks of gas generation and thermal runaway.

[0045] It should be noted that, in this embodiment, the relationship between the compounds containing element R in the second additive and the first additive follows the principle of "homogeneous elements, selectable forms." Specifically, both must be strictly limited to containing the same metallic element R (e.g., both Al or both Ti) to ensure the continuity and synergy of the chemical properties of the double-layer coating structure; however, there is flexibility in the specific form of the compound, that is, element R in the first additive and the second additive can take the same chemical form (e.g., both oxides) or different chemical forms (e.g., oxides, hydroxides, or fluorides, respectively). Therefore, the R-containing compound in the second additive and the R-containing compound in the first additive can be completely identical substances (e.g., both aluminum oxide) or different substances based on the same element R (e.g., the former is aluminum oxide, and the latter is aluminum fluoride).

[0046] In some embodiments, the element R includes at least one of Al, Ti, Zr, Nb, W, Mg, Ta, and Y; preferably, the element R is Al and / or Ti.

[0047] The above-mentioned elements are specific metal elements selected based on the "functionality" criteria (i.e., the ability to consume residual lithium and electrochemical inertness) defined in the aforementioned embodiments. They all have strong oxygen affinity and are stable in valence state within the voltage range of high-nickel cathode material operation (usually 2.8V-4.3V), and will not undergo redox reactions.

[0048] The chemical reaction principle lies in the fact that, during high-temperature sintering, compounds of these elements (such as oxides) act as reactants, actively "capturing" residual lithium sources (such as LiOH or Li2CO3) on the surface of the matrix material, resulting in a combination reaction. For example, aluminum (Al) can form aluminum lithium oxide (LiAlO2), titanium (Ti) can form lithium titanate (Li2TiO3), and zirconium (Zr) can form lithium zirconate (Li2ZrO3). The principle of structural stability is that these elements maintain a fixed valence state during charging and discharging (e.g., Al is always +3, Zr / Ti is always +4), forming a robust lattice that does not undergo drastic volume changes or structural collapse due to lithium ion insertion / extraction.

[0049] By consuming residual lithium on the surface in situ through chemical reaction, the alkalinity of the material surface is significantly reduced, improving the material's processing performance (preventing slurry gelation) and suppressing battery gas generation. The resulting lithium-metal composite oxide is typically an excellent fast-ion conductor, lowering the lithium-ion diffusion barrier at the interface and thus enhancing the material's rate performance. Due to the electrochemical inertness of these elements, the coating layer they form acts as a physical barrier during cycling, effectively isolating the highly active high-nickel substrate from the electrolyte, reducing side reactions, and improving the battery's cycle life and thermal stability.

[0050] In some embodiments, the compound containing element R is selected from at least one of oxides, hydroxides, and fluorides of element R.

[0051] This refers to the specific chemical form of the "additives" added to the mixture during the preparation process to construct the coating layer. After the sintering process, these forms are eventually transformed into stable components (i.e., "sintered material") in the coating layer.

[0052] Oxides and hydroxides are direct precursors for the formation of oxide coatings. When heated, hydroxides first decompose and lose water to form highly reactive oxides, which then more readily react with residual lithium on the surface in a solid-phase reaction.

[0053] For fluorides, fluorine (F) is introduced. At high temperatures, fluorides not only participate in the formation of the coating layer, but fluoride ions may also replace some oxygen ions in the lattice surface (F-doping) or form a corrosion-resistant metal fluoride / fluoride oxide layer.

[0054] Oxides and hydroxides are widely available, inexpensive, and thermally stable, making them suitable as coating materials for large-scale production. Enhanced corrosion resistance (a unique effect of fluorides): Introducing fluorides (such as AlF3) can form a fluorine-containing protective layer on the material surface. Due to the extremely high electronegativity and strong chemical bond energy of fluorine, the fluorine-containing layer significantly resists the corrosion of acidic substances in the electrolyte (such as HF), further inhibiting the dissolution of transition metal ions, thereby greatly improving the cycling stability of the material under high temperature and high pressure. Specific compound forms (such as hydroxides or nanoscale oxides) have high specific surface area and reactivity, which helps to promote the "alkali removal" reaction at lower sintering temperatures, ensuring the uniformity and integrity of the coating layer.

[0055] In some embodiments, the first additive comprises at least one of Al2O3, LiAlO2, and Al(OH)3.

[0056] The aforementioned first additive includes at least two of Al2O3, LiAlO2, and Al(OH)3. This aluminum-based additive (such as Al2O3) reacts with residual lithium (such as Li2CO3) on the material surface during high-temperature sintering. One of the reaction products can be LiAlO2 (aluminum lithium oxide). This substance is a "fast ion conductor," offering a dual advantage: (1) Reduce residual alkali: harmful residual lithium on the surface is consumed through reaction.

[0057] (2) Lowering the energy barrier: The formed LiAlO2 conductive layer itself helps lithium ions pass through quickly, reducing the interface impedance.

[0058] At the same time, the coating material penetrates into the material, filling the gaps between particles and enhancing the overall structural strength of the material. This helps to suppress cracks in the material during repeated charging and discharging, thereby improving cycle life and safety.

[0059] In some embodiments, the second additive comprises H3BO3, and at least one of Al2O3, Al(OH)3 and AlF3.

[0060] The aforementioned second coating layer is the second "protective shell" wrapped around the outermost layer. It is also defined as "a sintered product derived from the second additive". The second additive is a complex containing at least one of H3BO3 (boric acid) and Al2O3 (aluminum oxide), Al(OH)3 (aluminum hydroxide), and AlF3 (aluminum fluoride).

[0061] This layer utilizes a complementary coating mechanism. Specifically, for the boron (B) in this layer, H3BO3 (boric acid) melts at high temperatures, allowing for uniform coating and reacting with residual alkali to form lithium borate compounds. Lithium borate is also a fast ion conductor, increasing initial discharge capacity and further reducing battery impedance. For the aluminum (Al) in this layer, the aluminum compounds (such as Al2O3) undergo sintering (potentially forming LiAlO2), primarily acting as a physical protective barrier. This isolates the cathode material from the electrolyte, suppressing harmful side reactions. This boron + aluminum combination outperforms single-component coatings in suppressing side reactions, improving ion transport, and enhancing thermal stability.

[0062] In some embodiments, the matrix material has internal pores.

[0063] Alternatively, the matrix material may be a material with a loose and porous structure, and the internal grains may be arranged radially divergently.

[0064] In this embodiment, based on the high-nickel cathode material of the aforementioned embodiments, the microstructure characteristics of the matrix material are further defined.

[0065] The matrix material is not a dense, solid structure, but rather a material with internal pores. It can also be a porous material with internal pores, exhibiting a loose, porous structure at the microscopic level. Furthermore, the internal grains constituting the matrix material are arranged in a radially divergent pattern.

[0066] The beneficial effects of this loose and porous structure and specific grain arrangement are as follows: First, it can improve the wettability of the electrolyte. The presence of pores significantly increases the contact interface between the electrolyte and the active material, allowing the electrolyte to more fully wet the interior of the material. Second, it increases the ion diffusion path. The open pores provide more diffusion channels for lithium ions, shortening their transport distance in the solid phase.

[0067] The combined effect of these factors allows the material's capacity to be fully utilized and effectively improves its rate performance.

[0068] Furthermore, the cross-sectional porosity of the matrix material is 2% to 7% (e.g., the porosity can be 2%, 3%, 4%, 5%, 6%, 7%, etc.). In a preferred embodiment, the cross-sectional porosity of the matrix material is 3% to 5%.

[0069] In some embodiments, M' in the general chemical formula represents Zr, Sr, and Al.

[0070] In some embodiments, the first additive comprises Al2O3 and LiAlO2.

[0071] In this embodiment, one of the functions of the first coating layer is to react with residual lithium on the material surface to generate a fast ion conductor, LiAlO2 (aluminum lithium oxide). By directly using a combination of Al2O3 (as reactant) and LiAlO2 (as product), this fast ion conductor layer can be formed on the material surface more efficiently.

[0072] The beneficial effects of this optimized combination include effectively reducing residual alkali on the material surface, lowering the energy barrier for lithium-ion diffusion, and increasing the diffusion rate of lithium-ions at the interface. Simultaneously, the sintered material formed by this additive penetrates into the material's interior, filling interparticle gaps, enhancing the overall structural strength of the material, and inhibiting the formation of crystal cracks, thereby strengthening interfacial stability and improving the material's cycle life and safety.

[0073] In some embodiments, the mass of Al in the first coating layer in the final product is 500ppm to 3000ppm (e.g., 500ppm, 1000ppm, 1500ppm, 2000ppm, 2500ppm, 3000ppm, etc.); or, the mass of Al in the first coating layer in the final product is 1000ppm to 2000ppm (e.g., 1000ppm, 1200ppm, 1400ppm, 1600ppm, 1800ppm, 2000ppm, etc.).

[0074] The quality of the final product described above refers to a specific mass range of Al element in the first coating layer. It should be noted that sufficient Al is required to perform its function (such as reacting to form the fast ion conductor LiAlO2, filling intergranular gaps, etc.). The lower limit is >500 ppm; if the content is too low, the effect on enhancing material stability is not significant. The upper limit is <3000 ppm; if the content is too high, the coating material will form an excessively thick coating layer on the material surface. This excessively thick layer (Al oxides or lithiumates typically have poor conductivity) increases impedance, leading to a decrease in material conductivity and significantly inhibiting the material's capacity.

[0075] In some embodiments, the mass of B in the second coating layer in the final product is 300ppm to 3000ppm (e.g., it can be 300ppm, 500ppm, 1000ppm, 1500ppm, 2000ppm, 2500ppm, 3000ppm, etc.); or, the mass of B in the second coating layer in the final product is 500ppm to 1500ppm.

[0076] The above limits refer to a specific range for boron (B) in the second coating layer. Boron's role is to react and generate fast ion conductors such as lithium borate, thereby increasing capacity and reducing impedance. Its lower limit is >300 ppm; if the coating amount is too low, its capacity-enhancing effect is limited. Its upper limit is <3000 ppm; if the coating amount is too high, borate and other substances are prone to forming agglomerated particles on the material surface.

[0077] It should be noted that this aggregation can lead to uneven coating, with some areas being too thickly coated and hindering lithium-ion transport; while other areas with thin coating still have the risk of side reactions.

[0078] In some embodiments, the mass of Al in the second coating layer in the final product is 0 ppm to 3000 ppm (e.g., it can be 0 ppm, 100 ppm, 300 ppm, 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, etc.); or, the mass of Al in the second coating layer in the final product is 500 ppm to 1500 ppm.

[0079] The above limits define a specific range for Al in the second coating layer. Here, Al primarily acts as a physical barrier, forming a complementary mechanism with B (boron). The lower limit is 0 ppm, meaning that the Al component in the second coating layer is optional (i.e., B-Al complementary coating, or B coating alone). The upper limit is <3000 ppm, and this upper limit must be controlled. Excessive Al coating (as a physical barrier) significantly increases the surface impedance of the material and may hinder lithium-ion insertion and extraction, thereby reducing the battery's rate performance and overall energy density.

[0080] refer to Figure 1 This application also provides a method for preparing a high-nickel cathode material as described in any of the foregoing embodiments, comprising: Step S1: The precursor, lithium source and third additive are mixed and sintered for the first time in an oxidizing atmosphere.

[0081] This step is the "chip-making" step for the cathode material. Its purpose is to synthesize the matrix material as described in the aforementioned embodiments by means of a high-temperature solid-state reaction, including the precursors providing Ni / Co / Mn, the lithium source providing Li, and the third additives providing M' elements such as Zr / Sr / Al.

[0082] Specifically, the precursor, lithium hydroxide, and Zr / Sr / Al oxides (the third additive) are mixed uniformly. Heating is then performed in an oxygen-rich atmosphere (e.g., 90% oxygen concentration).

[0083] This step ultimately yields a first-sintered product, which is a basically formed, doped "matrix material," but its surface is not yet coated and may have residual alkali attached.

[0084] Step S2: The product from the first sintering is mixed with the first additive and then sintered a second time in an oxidizing atmosphere.

[0085] This step is the "first coating" step. The purpose is to form the "first coating layer" on the surface of the base material by sintering the "first additive" (such as Al2O3 and LiAlO2) at high temperature.

[0086] Step S3: The product obtained from the secondary sintering is washed with water to obtain a washed product.

[0087] This step is the "cleaning" step. Its purpose is to wash away the impurities remaining on the surface of the material after the first two high-temperature sintering steps, mainly residual lithium (such as Li2CO3 or LiOH).

[0088] Step S4: The water-washed product is mixed with the second additive and sintered for the third time in an oxidizing atmosphere to obtain the high-nickel cathode material.

[0089] This step is the "second coating" step. The purpose is to form a "second coating layer" on top of the "first coating layer" by sintering the "second additives" (such as H3BO3 and Al2O3) of the B+Al system at a relatively low temperature.

[0090] In summary, this preparation method provides a specific process sequence, and its core advantage lies in overcoming the defect of traditional water washing processes that damage the material surface structure when removing residual alkali. Specifically, this method does not directly wash the substrate material with water. Instead, during the second sintering (S2), a protective first coating layer is first formed on the material surface. This coating layer enhances the overall structural strength of the material and strengthens interfacial stability. Only on this basis is the water washing process performed (S3). This means that the water washing step (S3) targets the material already protected by the first coating layer, rather than the exposed substrate. At the same time, this water washing step can avoid the damage to the material structure and the precipitation of bulk lithium caused by excessively high liquid-solid ratios through precise control of process parameters (such as a liquid-to-solid ratio of 0.4~1.0). Therefore, this method can effectively remove residual lithium from the material surface while avoiding damage to the surface structure of high-nickel materials during water washing, ultimately achieving material modification without sacrificing the structural integrity of the material.

[0091] In some embodiments, the third additive includes at least three of oxides or hydroxides of Zr, Sr, Al, Sb, Y, and Ta.

[0092] In some embodiments, the step of mixing the precursor, lithium source and third additive further includes adding a pore-forming agent.

[0093] In some embodiments, the pore-forming agent includes at least one of aluminum sulfate, magnesium sulfate, and lithium sulfate.

[0094] In some embodiments, the pore-forming agent is a sulfate, and the amount of sulfate added is in the form of SO4. 2- The mass fraction is 0.05% to 2% of the precursor mass (e.g., 0.05%, 0.1%, 0.2%, 0.25%, 0.3%, 0.5%, 0.8%, 1%, 1.5%, 2%, etc.); or, the pore-forming agent is a sulfate, and the amount of sulfate added is expressed as SO42-. 2- The mass of the precursor is 0.2% to 1% of its mass.

[0095] In the mixing stage (S1) of the method for preparing the matrix material in this embodiment, in addition to the precursor, lithium source and third additive, a functional auxiliary agent, a pore-forming agent, is added.

[0096] The purpose of adding this sulfate pore-forming agent is to create pores within the matrix material through two synergistic mechanisms during the subsequent high-temperature "first sintering" step. The sulfate ions (SO4) in the pore-forming agent... 2- At high temperatures, the pore-forming agent decomposes and releases gases. When this gas generation rate matches the sintering temperature, uniformly distributed open pores can be formed within the material. Al, Li, and Mg metal ions in the pore-forming agent partially replace transition metal ions in the ternary material lattice. This substitution induces lattice distortion. These lattice defects migrate and aggregate at high temperatures, forming grain boundary vacancies, further promoting pore growth. Furthermore, these metal ions introduced as pore-forming agents (especially Al and Mg) remain in situ within the material lattice after the high-temperature reaction, exerting their intrinsic doping modification effect, effectively enhancing the robustness of the lattice structure, thereby synergistically improving the material's cycle stability.

[0097] Introducing pores into the matrix material through the aforementioned mechanism can lead to significant performance improvements. Firstly, the formed pores increase the specific surface area of ​​the material, allowing the electrolyte to more fully wet the interior. The open pores provide more diffusion channels for lithium ions. The improved wettability and diffusion pathways ultimately allow the material to fully utilize its capacity and improve rate performance. Furthermore, the amount of this pore-forming agent added needs to be precisely controlled (e.g., with SO4). 2-(calculated as 0.05% to 2% of the mass of the precursor). If the addition amount is too small, the formed pores will be insufficient and the performance improvement will be limited; while if the addition amount is too large, it will lead to excessive pores and loose grain connection, instead reducing the mechanical strength and safety performance of the material.

[0098] In some embodiments, the liquid-solid ratio of the water washing treatment is 0.4 to 1.0. For example, it can be 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, etc.

[0099] In this embodiment, it provides the ratio between the mass of the washing liquid (water) used in the S3 water washing step of the preparation process and the mass of the solid to be washed (the secondary sintered product).

[0100] The water washing treatment has a dual purpose, to wash away the residual lithium compounds (such as residual alkali) on the material surface to improve the subsequent processing performance of the material (such as preventing the slurry from gelling), and to wash away the possible residual SO4 2- ions (derived from the pore-forming agent that may be added in the S1 step).

[0101] Precisely controlling the liquid-solid ratio within the specific range of 0.4 to 1.0 is to achieve a key balance between "washing effect" and "structural damage". For the lower limit (≥0.4), if the liquid-solid ratio is too low (i.e., too little water), the washing will be insufficient and the washing effect will be poor, resulting in the still existence of residual alkali or residual SO4 2- ions. For the upper limit (≤1.0), if the liquid-solid ratio is too high (i.e., too much water), it will trigger the inherent defect of the high-nickel material: excessive water will damage the surface structure of the material, leading to the precipitation of lithium (Li) in the bulk phase, and ultimately making the electrochemical performance of the material worse. Therefore, the range of 0.4 to 1.0 is an optimized process window, which can not only ensure sufficient washing effect but also avoid the structural damage to the material itself caused by excessive water washing.

[0102] In some embodiments, the precursor includes Ni a M b (OH)2; where 0.80 ≤ a ≤ 0.98, 0 < b ≤ 0.20, a + b = 1, and M represents at least two of Co, Mn, and Al.

[0103] Ni a M b (OH)2 clarifies that a hydroxide precursor is used. This is the "base" raw material used in the S1 step to be mixed and sintered with the lithium source and the third additive. 0.80 ≤ a ≤ 0.98 defines that this precursor is a high-nickel precursor because the molar ratio a representing nickel (Ni) is always greater than or equal to 0.80.

[0104] M is not a single element, but a combination of at least two of the three common stable elements: cobalt (Co), manganese (Mn), and aluminum (Al). a+b=1 is a chemical balance that ensures that the total molar ratio of the main metals (Ni and M) in the precursor is 1.

[0105] In some embodiments, the first sintering includes a first heat preservation platform and a second heat preservation platform.

[0106] The heat treatment curve for step S1 (core making) is defined in the above steps. It is not a simple heating and holding process, but a two-step holding process.

[0107] Furthermore, the temperature of the first insulation platform is 350℃~650℃ (for example, it can be 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, etc.); and / or, the insulation time of the first insulation platform is 2 hours~6 hours; for example, it can be 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, etc.

[0108] The primary function of the aforementioned first thermal insulation platform (350℃~650℃) is to allow the lithium salt and precursor to fully dehydrate and decompose, placing them in an ideal reaction state. This is beneficial for improving the final crystallinity of the material. Temperatures that are too low (e.g., below 350℃) will result in low crystallinity and poor electrochemical performance; temperatures that are too high (e.g., above 650℃) may cause the crystal structure to collapse prematurely.

[0109] Furthermore, the temperature of the second insulation platform is 680℃~900℃ (for example, it can be 680℃, 700℃, 750℃, 800℃, 850℃, 900℃, etc.); and / or, the insulation time of the second insulation platform is 6 hours~16 hours. For example, it can be 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 12 hours, 15 hours, 16 hours, etc.

[0110] The aforementioned second thermal insulation platform (680℃~900℃) serves as the main reaction platform. Its function is to ensure the full progress of the oxidation reaction and the formation of the target crystalline phase. If a pore-forming agent (such as sulfate) is added, this temperature must also match the thermal decomposition temperature of the sulfate. If the temperature is too low (e.g., below 680℃), the material reaction will be incomplete, resulting in low crystallinity; if the temperature is too high (e.g., above 900℃), oxygen-deficient compounds are easily formed, promoting secondary recrystallization, leading to larger grains and a smaller specific surface area, which is detrimental to the extraction and insertion of lithium ions.

[0111] In some embodiments, the holding temperature for the second sintering is 500°C to 700°C. For example, it can be 500°C, 550°C, 600°C, 650°C, 700°C, etc.

[0112] In some embodiments, the isothermal duration of the second sintering is 5 to 10 hours. For example, it can be 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, etc.

[0113] The purpose of the second sintering is not only to form the first coating layer on the material surface, but also to allow the coating material (Al-based) to partially penetrate into the material interior, filling the intergranular pores to improve the material's structural stability and safety performance. If the temperature is too low (e.g., below 500℃), the coating layer is only concentrated on the material surface, merely acting as a physical barrier and offering little improvement in safety performance. Conversely, if the temperature is too high (e.g., above 700℃), substances such as alumina will be excessively incorporated into the crystal lattice, which can lead to a decrease in sample capacity and initial efficiency.

[0114] In some embodiments, the holding temperature for the third sintering is 200°C to 400°C. For example, it can be 200°C, 250°C, 300°C, 350°C, 400°C, etc.

[0115] In some embodiments, the isothermal duration of the third sintering is 5 to 10 hours. For example, it can be 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, etc.

[0116] The above steps define the heat treatment parameters for S4 (second coating). These parameters represent a relatively low-temperature sintering step, with the temperature (200℃~400℃) set primarily to match the reaction characteristics of the second additive (especially boric acid).

[0117] The purpose is to form a second coating layer (B+Al system) on the material surface. If the temperature is too low (e.g., below 200℃), the boric acid reaction will be insufficient and the coating effect will not be achieved. If the temperature is too high (e.g., above 400℃), the boric acid will decompose or react excessively, which will not only destroy the function of the coating layer, but may even damage the material itself.

[0118] This application also provides an electrode comprising the high-nickel cathode material as described in any of the foregoing embodiments. Alternatively, it comprises the high-nickel cathode material prepared by the preparation method described in any of the foregoing embodiments.

[0119] This application also provides a positive electrode as described above. The positive electrode can be prepared using conventional techniques in the art. For example, the modified high-nickel positive electrode material described in any of the foregoing embodiments can be used as the positive electrode active material, mixed with a conductive agent (e.g., carbon black, acetylene black, etc.) and a binder (e.g., polyvinylidene fluoride PVDF, etc.) in a suitable solvent (e.g., N-methylpyrrolidone NMP, etc.), and stirred to disperse it evenly, forming a positive electrode slurry with a specific viscosity. The positive electrode slurry is then uniformly coated onto the surface of a positive electrode current collector (e.g., aluminum foil), followed by drying, rolling, and cutting processes to obtain the positive electrode.

[0120] This application also provides a battery, including electrodes as described in the foregoing embodiments.

[0121] The aforementioned battery may also include, but is not limited to, a negative electrode, an electrolyte, and a separator disposed between the positive electrode and the negative electrode. The positive electrode, negative electrode, and separator can be formed into a cell structure by means of winding or stacking, etc. The cell is immersed in an electrolyte (e.g., electrolyte solution) and is entirely encapsulated in a battery casing (e.g., aluminum-plastic film or steel / aluminum casing).

[0122] The negative electrode may include a negative electrode active material capable of reversibly inserting and de-inserting lithium ions, such as graphite, silicon-based materials, tin-based materials, or lithium metal. The separator may be a porous polymer membrane such as polyethylene (PE) or polypropylene (PP). The electrolyte may be a liquid, gel, or all-solid-state electrolyte.

[0123] The type of battery is not particularly limited, but may include, for example, lithium secondary batteries, lithium-ion batteries, lithium metal batteries, solid-state batteries or quasi-solid-state batteries.

[0124] This application also provides an electrical device, including a battery as described in the foregoing embodiments.

[0125] The aforementioned electrical equipment, also known as electronic equipment, uses a battery as its power source, for example, to provide the electrical energy required for the device to operate. The specific form of the electronic equipment is not limited and may include, but is not limited to: electric vehicles, electric bicycles, electric motorcycles, power tools, drones, portable electronic devices (such as smartphones, laptops, tablets, and portable vacuum cleaners), and any device or system that requires battery power, such as electrochemical energy storage systems (ESS).

[0126] The present invention will be further illustrated below with specific embodiments. However, it should be understood that these embodiments are merely for the purpose of more detailed illustration and should not be construed as limiting the present invention in any way.

[0127] Example 1 In this embodiment, a high-nickel cathode material was prepared.

[0128] Experimental methods: (1) In an environment with 90% oxygen concentration, according to the chemical formula of the target matrix material, LiNi 0.95 Co 0.04 Mn 0.01 M' 0.02 O2, where M'=Zr 0.004 Sr 0.002 Sb 0.002 Al 0.002 Ni a M b (OH)2, lithium hydroxide monohydrate, third additive and pore-forming agent are mixed evenly, and then sintered once. After cooling, the mixture is crushed to obtain the first sintered product. precursor Ni a M b The chemical formula of (OH)2 is Ni 0.95 Co 0.04 Mn 0.01 (OH)2;D 50 The particle size is approximately 13.5 μm; the molar ratio of lithium to precursor in the lithium salt is 1.04:1; The third additive is a mixture of zirconium oxide, strontium oxide, antimony oxide and aluminum oxide, with the mixing ratio calculated according to the composition of M'; The pore-forming agent is aluminum sulfate, and the amount added is 0.3% of the precursor mass.

[0129] The sintering process includes a first holding platform and a second holding platform, which are carried out sequentially. The temperature is increased to the first holding platform at 1.5℃ per minute and then held at that temperature. The temperature is then increased to the second holding platform at 1.5℃ per minute and held again. The constant temperature of the first holding platform is 500℃ for 2 hours, and the constant temperature of the second holding platform is 750℃ for 12 hours.

[0130] (2) The first sintering product obtained in step (1) is mixed with the first additive and sintered at 610°C for 8 hours. After cooling, it is passed through a 325-mesh sieve to obtain the second sintering product. The first additive is alumina, and the dosage is calculated based on 1000 ppm of Al element in the primary sintering product.

[0131] (3) Wash the secondary sintering product obtained in step (2) with pure water, wherein the mass ratio of pure water to primary sintering product is 0.7:1, the washing temperature is 15℃, and the washing time is 10min; then dry at 120℃ to obtain the washed product. (4) The product obtained in step (3) is mixed with the second additive and sintered three times at 300°C for 8 hours. The mixture is then passed through a 325-mesh sieve to obtain the modified high-nickel cathode material of this application.

[0132] The second additive is aluminum oxide and boric acid; the amount of aluminum oxide added is 800 ppm of the water-washed product based on Al element, and the amount of boric acid added is 800 ppm of the water-washed product based on B element.

[0133] Example 2 In this embodiment, a high-nickel cathode material was prepared.

[0134] The experimental method is basically the same as that in Example 1, except that: In step (1), the amount of pore-forming agent (aluminum sulfate) added is 0.05% of the precursor mass.

[0135] Example 3 In this embodiment, a high-nickel cathode material was prepared.

[0136] The experimental method is basically the same as that in Example 1, except that: In step (1), the amount of pore-forming agent (aluminum sulfate) added is 2.0% of the precursor mass.

[0137] Example 4 In this embodiment, a high-nickel cathode material was prepared.

[0138] The experimental method is basically the same as that in Example 1, except that: In step (3), the mass ratio of pure water to secondary sintering product is 0.4:1.

[0139] Example 5 In this embodiment, a high-nickel cathode material was prepared.

[0140] The experimental method is basically the same as that in Example 1, except that: In step (3), the mass ratio of pure water to secondary sintering product is 1.0:1.

[0141] Example 6 In this embodiment, a high-nickel cathode material was prepared.

[0142] The experimental method is basically the same as that in Example 1, except that: In step (1), the chemical formula of the target matrix material is LiNi. 0.95 Co 0.04 Mn 0.01 M' 0.02 O2, where M'=Zr 0.01 Sr 0.005 Al0.005 The third additive was adjusted accordingly to be a mixture of zirconium oxide, strontium oxide and aluminum oxide.

[0143] Example 7 In this embodiment, a high-nickel cathode material was prepared.

[0144] The experimental method is basically the same as that in Example 1, except that: In step (2), the first additive is a mixture of alumina and aluminum lithium oxide (LiAlO2), and the amount of the mixture is still 1000 ppm of the primary sintering product based on Al element.

[0145] Example 8 In this embodiment, a high-nickel cathode material was prepared.

[0146] The experimental method is basically the same as that in Example 1, except that: In step (1), the pore-forming agent is replaced with magnesium sulfate, and the amount added is still 0.3% of the precursor mass.

[0147] Example 9 In this embodiment, a high-nickel cathode material was prepared. The experimental method was basically the same as in Example 1, except that in steps (2) and (4), the alumina used as the coating material was replaced with an equal molar amount of titanium dioxide (TiO2) to verify the effect when element R was Ti. Specifically, in step (2), the first additive was titanium dioxide, and the dosage was calculated based on 1000 ppm of Ti element in the first sintering product. In step (4), the second additive was titanium dioxide and boric acid; the amount of titanium dioxide added was 800 ppm of the water-washed product based on Ti element, and the amount of boric acid added was 800 ppm of the water-washed product based on B element.

[0148] Example 10 In this embodiment, a high-nickel cathode material was prepared. The experimental method was basically the same as in Example 1, except that in steps (2) and (4), alumina, which was used as the coating material, was replaced with an equal molar amount of zirconium oxide (ZrO2) to verify the effect when element R was Zr. Specifically, in step (2), the first additive was zirconium oxide, and the dosage was calculated based on 1000 ppm of Zr element in the first sintering product. In step (4), the second additive was zirconium oxide and boric acid; the amount of zirconium oxide added was 800 ppm of the water-washed product based on Zr element, and the amount of boric acid added was 800 ppm of the water-washed product based on B element.

[0149] Example 11 In this embodiment, a high-nickel cathode material was prepared. The experimental method was basically the same as in Example 1, except that: in step (4), aluminum fluoride (AlF3) was used instead of alumina as the aluminum source in the second additive to verify the effect of the fluoride form. Specifically: in step (4), the second additive was aluminum fluoride and boric acid; the amount of aluminum fluoride added was 800 ppm of the water-washed product based on Al element (and F element was introduced at the same time), and the amount of boric acid added was 800 ppm of the water-washed product based on B element.

[0150] Example 12 In this embodiment, a high-nickel cathode material was prepared. The experimental method was basically the same as in Example 1, except that the upper limit of the coating amount range in the claims was verified to affect the performance. Specifically, in step (2), the amount of the first additive (alumina) was 2800 ppm of the primary sintering product (close to the upper limit of 3000 ppm) based on Al element. In step (4), the amount of alumina added in the second additive was 2500 ppm of the water-washed product based on Al element, and the amount of boric acid added was 2500 ppm of the water-washed product (close to the upper limit of 3000 ppm) based on B element.

[0151] Comparative Example 1 In this comparative example, a cathode material was prepared.

[0152] The experimental method is basically the same as that in Example 1, except that: In step (4), the second additive uses only alumina (the dosage is calculated based on 800 ppm of Al element in the first sintering product), and boric acid is not added.

[0153] Comparative Example 2 In this comparative example, a cathode material was prepared.

[0154] The experimental method is basically the same as that in Example 1, except that: The washing and drying steps in step (3) are omitted.

[0155] The product of step (2) (secondary sintering product) is not washed with water and is directly mixed with the second additive for the third sintering in step (4).

[0156] Comparative Example 3 In this comparative example, a cathode material was prepared.

[0157] The experimental method is basically the same as that in Example 1, except that: In step (3), the mass ratio of pure water to secondary sintering product is 1.5:1 (which exceeds the range of "≤1.0").

[0158] Comparative Example 4 In this comparative example, a cathode material was prepared.

[0159] The experimental method is basically the same as that in Example 1, except that: In step (1), the amount of pore-forming agent (aluminum sulfate) added is 0.01% of the precursor mass (below the range of "≥0.05%").

[0160] Comparative Example 5 In this comparative example, a cathode material was prepared.

[0161] The experimental method is basically the same as that in Example 1, except that: In step (1), no pore-forming agent is added.

[0162] Test Experiment 1. Testing method: (1) Capacity testing method: The button cell batteries were tested at 25℃ using the Blue Electric Test Cabinet. With 1C = 190mA / g set, charge / discharge was performed at 0.1C within a voltage range of 2.8V to 4.3V. Specifically, the batteries were charged at a constant current of 0.1C to 4.3V, then charged at a constant voltage of 4.3V until the cutoff current reached 0.02C. After a 5-minute rest, the batteries were discharged at 0.1C to 2.8V and rested for another 5 minutes. The charge / discharge capacity was recorded as the first-week charge / discharge capacity. The initial efficiency (%) = (first-week discharge capacity / first-week charge capacity) × 100%.

[0163] (2) Cyclic performance testing method: The charge-discharge cycle characteristics of button cells were tested using a Blue Electric test cabinet at 45℃, with 1C = 190mA / g. Charge and discharge were performed at 1C within a voltage range of 2.8V to 4.3V. Specifically, the cells were charged at a constant current of 1C to 4.3V, then charged at a constant voltage of 4.3V to a cutoff current of 0.02C, rested for 5 minutes, and then discharged at 1C to 3.0V, rested for 5 minutes. The charge-discharge capacity after the first cycle was recorded. This cycle was repeated for 60 charge / discharge cycles, and the charge-discharge capacity after the 60th cycle was recorded. Cycle capacity retention (%) = (60th cycle discharge capacity / 1st cycle discharge capacity) × 100%.

[0164] (3) Cross-sectional porosity test method: The method for testing the percentage of porosity (including hollow structures) is as follows: five ion-cut cross-sectional images are taken at a magnification of 7k. For example, high-nickel cathode material particles with a cross-sectional diameter of 9-11μm after cutting can be selected for measurement. At this time, the cross-sectional image is approximately at the center of the high-nickel cathode material particle. Specifically, MIPAR analysis software is used to automatically identify and calculate the pores and hollow structures in the cross-section, and read the proportion of these blank positions to the total area.

[0165] 2. Test Results: Table 1. Electrochemical performance results of the high-nickel cathode materials obtained in the examples and comparative examples.

[0166] Table 2. Cross-sectional porosity results of high-nickel cathode materials obtained from the examples and comparative examples.

[0167] 3. Analysis: (1) Overall Performance Analysis As shown in Tables 1 and 2, the high-nickel cathode materials (Examples 1-8) obtained using the preparation method described in this invention all exhibit excellent electrochemical performance. Specifically, within the defined parameter range, the first-cycle discharge specific capacity of the obtained materials remained above 230 mAh / g, and the capacity retention rate after 60 cycles was ≥92.4%. This excellent comprehensive performance is attributed to the unique structural design of this invention, which combines a loose porous matrix with a double-layer synergistic coating, making it particularly suitable for high-end applications such as low-altitude aircraft, power batteries, and robotic bodies, where energy density and cycle life are critically demanding.

[0168] (2) Synergistic effect analysis of boron (B) in the second coating layer: Comparison of Example 1 and Comparative Example 1 shows the key role of the second coating layer composition. The first-cycle discharge capacity of Example 1 (containing B+Al second coating layer) was 232.3 mAh / g, while that of Comparative Example 1 (containing only Al second coating layer, without B) dropped to 227.9 mAh / g, with a capacity loss of 4.4 mAh / g; at the same time, the cycle retention rate also decreased from 93.7% to 92.0%. This result strongly proves the inference of the "complementary mechanism" in the specification: Al oxide alone can provide a physical barrier, but its conductivity is poor; while after the introduction of boron (B), the lithium borate series compounds generated at high temperature act as fast ion conductors, effectively reducing the interfacial impedance, thereby significantly releasing the capacity of the material. At the same time, the synergistic presence of B and Al constructs a complete protective layer with both high conductivity and high chemical stability, thereby improving cycle stability.

[0169] (3) Balance analysis of the effect of water washing process on surface structure and performance Comparative example 1, comparative example 2 (no water washing) and comparative example 3 (excessive water washing, liquid-solid ratio 1.5:1) reveals the critical significance of water washing process parameters.

[0170] Regarding the issue of not washing with water, although Comparative Example 2 appears to have a high cycle retention rate (94.5%), its discharge capacity is only 223.4 mAh / g (the lowest among all groups, nearly 9 mAh / g lower than Example 1). This is because the lack of water washing results in a large amount of residual alkali remaining on the material surface, which severely hinders the insertion and extraction of lithium ions and increases polarization resistance.

[0171] Regarding the issue of excessive water washing, although Comparative Example 3 has a higher capacity (233.5 mAh / g), its cycle retention rate is only 91.0% (significantly lower than Example 1). As described in the background section of the specification, an excessively high liquid-to-solid ratio (>1.0) leads to excessive proton-lithium ion exchange, inducing the precipitation of lithium in the crystal lattice and the collapse of the surface layered structure, forming an electrochemically inert layer, thereby deteriorating the long-term cycle stability of the material. Therefore, this invention controls the liquid-to-solid ratio at 0.4~1.0, precisely achieving the optimal balance between "removing residual alkali" and "protecting crystal lattice integrity."

[0172] (4) Analysis of the influence of pore-forming agents on microstructure and properties: Comparative Examples 1-3 and Comparative Examples 4-5, and in conjunction with the porosity data in Table 2 and Figures 1-3 The SEM morphology can verify the dual gain mechanism of the pore-forming agent.

[0173] Examples 1-3 were prepared with an appropriate amount of pore-forming agent, and Table 2 shows that they have a cross-sectional porosity of 2.45% to 8.29% (e.g., ...). Figure 1 , Figure 2 As shown, the interior exhibits a clear radial pore pattern; while the porosity of Comparative Example 5, without the addition of a pore-forming agent, is only 0.96% (as shown). Figure 3 As shown, it is nearly dense and solid. In terms of electrochemical data, Example 1 exhibits a discharge capacity approximately 3 mAh / g higher than Comparative Example 5. This confirms that the loose, porous structure increases the electrolyte wetting channels, shortens the solid-phase diffusion path, and allows for full utilization of the active lithium within the particles.

[0174] It is worth noting that the cycle retention rate of Comparative Example 5 (without pore-forming agent) was only 91.8%, lower than that of Example 1 (93.7%). This confirms that the metal cations (such as Al, Mg, etc.) in the pore-forming agent achieve in-situ doping at high temperature, acting as "rivets" to stabilize the crystal structure and suppress phase transitions during cycling.

[0175] Regarding the dose-effect relationship, Comparative Example 4 (0.01% addition) showed no significant improvement in porosity (1.37%) due to its low addition amount, resulting in no essential difference in performance compared to Comparative Example 5. This further illustrates the necessity of controlling the pore-forming agent content within a specific range (e.g., 0.05%~2%).

[0176] (5) Comparative analysis of the applicability of different elements R and compound forms: The test results of Example 1 (Al-based) and Example 9 (Ti-based) and Example 10 (Zr-based) show that when Ti or Zr is used to replace Al as the coating element R, the material still maintains extremely high discharge capacity (>231mAh / g) and excellent cycle retention (>93%). This confirms that the "element R" defined in the claims is not limited to aluminum. Any metal element that has the ability to "react with residual lithium" and is "electrochemically inert" (such as Ti, Zr, etc.) can achieve the technical effect of the present invention through the same mechanism (alkali removal + physical barrier).

[0177] Furthermore, Example 11, using aluminum fluoride as a raw material, exhibited a cycle retention rate (94.5%) that was even slightly better than that of the oxide system, demonstrating that the R-containing compound could be in the form of a fluoride, and that the introduction of fluorine helps to further enhance the surface's corrosion resistance. Example 12 verified the rationality of the upper limit of the coating amount, indicating that even at higher coating amounts, the material can still maintain good overall performance.

[0178] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-nickel cathode material, characterized in that, The high-nickel cathode material includes a matrix material, a first coating layer covering the matrix material, and a second coating layer covering the first coating layer; The chemical formula of the matrix material is LiNi. x M y M' z O2; Wherein, 0.80≤x≤0.98, 0<y≤0.20, 0<z≤0.02, and x+y+z=1; M represents at least two of Co, Mn, and Al, and M' represents at least three of Zr, Sr, Al, Sb, Y, and Ta; The first coating layer comprises a sinter derived from a first additive; the first additive comprises a compound containing element R; The second coating layer comprises a sinter derived from a second additive; the second additive comprises a compound containing element R and a boron-containing compound; Wherein, element R is a metal element that can react with residual lithium on the surface of the matrix material during sintering to form a lithium-metal composite oxide, and does not participate in redox reactions within the operating voltage range of the high-nickel cathode material during charging and discharging.

2. The high-nickel cathode material as described in claim 1, characterized in that, The element R includes at least one selected from Al, Ti, Zr, Nb, W, Mg, Ta, and Y; preferably, the element R is Al and / or Ti; and / or, The compound containing element R is selected from at least one of oxides, hydroxides, and fluorides of element R; and / or, The first additive comprises at least one of Al2O3, LiAlO2, and Al(OH)3; and / or, The second additive comprises H3BO3, and at least one of Al2O3, Al(OH)3, and AlF3; and / or, The matrix material has pores inside; or, the matrix material is a material with a loose porous structure, and the internal grains are arranged radially divergently. Preferably, the cross-sectional porosity of the matrix material is 2% to 7%; Preferably, the cross-sectional porosity of the matrix material is 3% to 5%.

3. The high-nickel cathode material as described in claim 1, characterized in that, In the general chemical formula, M' represents Zr, Sr, and Al; and / or, The first additive contains Al2O3 and LiAlO2.

4. The high-nickel cathode material as described in claim 1, characterized in that, The mass of Al in the first coating layer in the final product is 500 ppm to 3000 ppm; or, the mass of Al in the first coating layer in the final product is 1000 ppm to 2000 ppm; and / or, The mass of B in the second coating layer in the final product is 300 ppm to 3000 ppm; or, the mass of B in the second coating layer in the final product is 500 ppm to 1500 ppm; and / or, The mass of Al in the second coating layer in the final product is 0 ppm to 3000 ppm; or, the mass of Al in the second coating layer in the final product is 500 ppm to 1500 ppm.

5. A method for preparing the high-nickel cathode material as described in any one of claims 1-4, characterized in that, include: The precursor, lithium source and third additive are mixed and sintered for the first time in an oxidizing atmosphere. The product from the first sintering is mixed with the first additive and then sintered a second time in an oxidizing atmosphere. The product from the secondary sintering was washed with water to obtain a washed product. The water-washed product is mixed with a second additive and sintered for the third time in an oxidizing atmosphere to obtain the high-nickel cathode material.

6. The method for preparing the high-nickel cathode material as described in claim 5, characterized in that, The third additive includes at least three of the oxides and hydroxides of Zr, Sr, Al, Sb, Y, and Ta; and / or, The step of mixing the precursor, lithium source and third additive also includes adding a pore-forming agent; Preferably, the pore-forming agent comprises sulfate; Preferably, the pore-forming agent includes at least one of aluminum sulfate, magnesium sulfate, and lithium sulfate; Preferably, the pore-forming agent is a sulfate, and the amount of sulfate added is in the form of SO4. 2- The mass of the precursor is 0.05% to 2% by weight; or, the pore-forming agent is a sulfate, and the amount of sulfate added is expressed as SO42-. 2- The mass of the precursor is 0.2% to 1% of its mass; and / or, The liquid-to-solid ratio of the water washing treatment is 0.4~1.0; and / or, The precursor includes Ni a M b (OH)2; where 0.80 ≤ a ≤ 0.98, 0 < b ≤ 0.20, a + b = 1, and M represents at least two of Co, Mn, and Al.

7. The method for preparing the high-nickel cathode material as described in claim 5, characterized in that, The first sintering includes a first heat preservation platform and a second heat preservation platform; Preferably, the temperature of the first insulation platform is 350℃~650℃; and / or, the insulation time of the first insulation platform is 2 hours~6 hours; Preferably, the temperature of the second insulation platform is 680℃~900℃; and / or, the insulation time of the second insulation platform is 6 hours~16 hours; and / or, The holding temperature for the second sintering is 500℃~700℃; and / or, The isothermal duration of the second sintering is 5 to 10 hours; and / or, The holding temperature for the third sintering is 200℃~400℃; and / or, The isothermal duration of the third sintering is 5 to 10 hours.

8. An electrode, characterized in that, Includes the high-nickel cathode material as described in any one of claims 1 to 4; or includes the high-nickel cathode material prepared by the preparation method described in any one of claims 5 to 7.

9. A battery, characterized in that, Includes the electrode as described in claim 8.

10. An electrical-related device, characterized in that, Includes the battery as described in claim 9.

Images