Ultrahigh nickel positive electrode material and preparation method and application thereof

Abstract

The invention relates to the technical field of lithium ion battery positive electrode materials, in particular to an ultrahigh nickel positive electrode material and a preparation method and application thereof. The invention provides an ultrahigh nickel positive electrode material, the molecular general formula of which is LiNixCoyM1aM2bO2, x + y + a + b = 1, x is more than or equal to 0.94 and less than 1, and y is more than 0 and less than 0.06; wherein M1 is selected from one of Zr, Nb and Ti, and the doping amount meets the condition that a is equal to 0.001-0.004; m2 is selected from one of Al and Mg, and the doping amount b is equal to 0.004-0.012. According to the ultrahigh nickel positive electrode material, on the basis that the inherent high-capacity characteristic of the ultrahigh nickel positive electrode material is maintained, remarkably improved cycling stability, obviously improved thermal safety and more optimized interface chemical characteristics are obtained at the same time, and a new technical path is provided for developing a high-performance lithium ion battery.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery cathode material technology, specifically to an ultra-high nickel cathode material, its preparation method, and its application. Background Technology

[0002] Ultra-high nickel ternary cathode materials (nickel content molar fraction greater than 90%) are a key system for achieving breakthroughs in the energy density of lithium-ion batteries, but their industrialization process is severely constrained by multiple inherent defects. These defects constitute an interconnected cycle of performance degradation: the material undergoes a drastic H2-H3 phase transition under high voltage, triggering lattice distortion and microcrack propagation, leading to the generation and propagation of intragranular microcracks, thus destroying its structural integrity; simultaneously, Ni... 2+ With Li + The mixing of cations between cells severely hinders lithium-ion transport channels, leading to capacity decay and deterioration of kinetic performance. Furthermore, poor thermal stability and high levels of residual alkali on the surface further exacerbate the risk of thermal runaway and interfacial side reactions. These interconnected defects collectively constitute a key bottleneck restricting its commercial application.

[0003] To address these challenges, elemental doping is a commonly adopted modification strategy in the industry. However, existing single-element doping schemes have limitations in achieving a synergistic improvement in the overall performance of materials due to their functional limitations. For example, while Al doping can enhance thermal stability to some extent, its effect on suppressing the H2-H3 phase transition and mitigating cation mixing is limited; while Mg doping can effectively suppress cation mixing, its improvement in intrinsic thermal stability is insufficient and may sacrifice initial capacity. This single-element modification strategy cannot simultaneously address multiple defects such as structural phase transitions, thermal runaway risks, cation mixing, and interfacial side reactions. Furthermore, introducing too many dopants in an attempt to comprehensively improve performance will introduce new problems: the interactions of multiple elements are difficult to predict and control, potentially leading to uncontrolled lattice distortion; the introduction of excessive inactive elements will dilute the electrochemically active components, causing capacity and energy density losses; at the same time, the synthesis process window for multi-element systems is significantly narrowed, and uniform element distribution and valence state control become extremely difficult, seriously affecting batch consistency and the feasibility of large-scale preparation. Therefore, how to achieve a synergistic improvement in overall performance through reasonable element combination design while ensuring high capacity remains a technical problem that needs to be solved in this field. Summary of the Invention

[0004] This invention provides an ultra-high nickel cathode material, its preparation method, and its application, in order to solve the problem that existing technologies cannot simultaneously address multiple defects in ultra-high nickel cathode materials, such as structural distortion, cation mixing, and interfacial side reactions, which lead to shortcomings in their overall performance.

[0005] In a first aspect, the present invention provides an ultra-high nickel cathode material with the general molecular formula LiNi. x Co y M1 a M2 b O2, and x+y+a+b=1, and 0.96≤x<1, 0<y<0.04; M1 is selected from Zr, Nb, and Ti, and the doping amount satisfies a = 0.001-0.004; M2 is selected from Al or Mg, and the doping amount satisfies b = 0.004-0.012.

[0006] In one optional implementation, M1 is Zr, M2 is Al, and the doping amounts of M1 and M2 satisfy a+b=0.005.

[0007] It should be noted that the doping levels of all elements in this invention are based on the general molecular formula LiNi. x Co y M1 a M2 b The calculations were performed based on 1 mol of transition metal sites (Ni+Co+M1+M2) in O2.

[0008] It should be noted that within the doping range of M1 and M2 provided by this invention, the synergistic effect of M1 and M2 is optimal. M1 stabilizes the material's "skeleton" through its high bond energy, providing a stable channel for the rapid transport of lithium ions; M2 effectively "purifies" the lithium layer, ensuring the unobstructed flow of the channel. The synergy between the two achieves a balance between "structural stability" and "interface / channel order," thus simultaneously obtaining low cation mixing, low surface residual alkali, high thermal runaway temperature, and excellent cycle retention without excessively sacrificing capacity.

[0009] When the doping amount is below this lower limit, the M1 element cannot form an effective "pinning" point in the lattice to fully suppress the H2-H3 phase transition and stabilize the crystal structure. The M2 element also cannot form sufficient spatial barriers to significantly reduce cation mixing. Its effect is negligible, and the material properties are close to those of the undoped material.

[0010] When the doping concentration exceeds the upper limit, both M1 and M2 are electrochemically inert elements. Excessive doping will directly dilute the content of electrochemically active materials (Ni, Co), leading to an irreversible loss of the material's reversible capacity. This range achieves the modification objective while maximizing the preservation of the material's high capacity characteristics.

[0011] M1 and M2 have a synergistic enhancement effect in suppressing cation mixing. Low cation mixing provides a smooth channel for the rapid diffusion of lithium ions, which is the basis for obtaining excellent rate performance and cycle performance.

[0012] In one alternative embodiment, the ultra-high nickel cathode material comprises polycrystalline secondary spherical particles constructed from a large number of nanoscale or submicron-scale primary grains.

[0013] Optionally, the microstructure of the polycrystalline secondary spherical particles is a regular sphere, which is formed by the agglomeration and sintering of nanoscale primary particles, forming a polycrystalline structure with grain boundaries and pores inside.

[0014] Optionally, the particle size of the polycrystalline secondary spherical particles is 7-14 μm.

[0015] In one optional embodiment, the ultra-high nickel cathode material undergoes cation mixing. I (003) / (104) >1.4; In one optional embodiment, the surface residual alkali content of the ultra-high nickel cathode material is <1.2wt%.

[0016] Secondly, the present invention provides a method for preparing an ultra-high nickel cathode material, comprising the following steps: S1, a nickel-cobalt hydroxide precursor, a lithium source, a compound containing element M1, and a compound containing element M2 are mixed to obtain a precursor mixture; S2, after two-stage sintering of the precursor mixture, it is crushed and sieved to obtain ultra-high nickel cathode material.

[0017] In one optional embodiment, the two-stage sintering includes heating to 450-550°C at a rate of 2-5°C / min and holding for 4-8 hours in a pure oxygen atmosphere, and heating to 740-780°C at a rate of 1-3°C / min and holding for 10-20 hours. In one optional embodiment, the molar ratio of Li:(Ni+Co+M1+M2) in the lithium source and the nickel-cobalt hydroxide precursor is 1.02-1.06, optionally 1.03.

[0018] In one optional embodiment, the compound containing element M1 includes one of ZrO2, Nb2O5, and TiO2; In one optional embodiment, the compound containing the M2 element includes one of Al(OH)3 and Mg(OH)2; In one optional embodiment, the lithium source includes one of LiOH·H2O and Li2CO3; In one alternative embodiment, the general formula of the nickel-cobalt hydroxide precursor includes Ni x Co y (OH)2, where 0.94≤x<1, x+y=1; Optionally, the nickel-cobalt hydroxide precursor is Ni 0.96 Co 0.04 (OH)2.

[0019] Thirdly, the present invention also provides a lithium-ion battery, comprising the above-mentioned ultra-high nickel cathode material or the ultra-high nickel cathode material prepared by the above-mentioned preparation method.

[0020] Those skilled in the art will understand that the lithium-ion battery provided by the present invention may include structural components such as an electrolyte, a positive electrode, a negative electrode, a separator, and a casing. During the charging and discharging process, lithium ions repeatedly insert and extract between the positive and negative electrode. The electrolyte acts as a conductor between the positive and negative electrode. The separator is disposed between the positive and negative electrode, primarily to prevent short circuits between the positive and negative electrodes, while simultaneously allowing lithium ions to pass through.

[0021] As an example, the positive electrode sheet includes a positive current collector and a positive active layer. The positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active layer is disposed on either or both of the opposite surfaces of the positive current collector. The materials, composition, and manufacturing methods of the positive electrode sheet used in the lithium-ion battery of the present invention may include any techniques disclosed in the prior art.

[0022] As an example, the negative electrode sheet includes a negative electrode current collector and a negative electrode active layer. The negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode active layer is disposed on either or both of the opposing surfaces of the negative electrode current collector. The materials, composition, and manufacturing methods of the negative electrode sheet used in the lithium-ion battery of the present invention may include any techniques disclosed in the prior art.

[0023] The material and shape of the separator used in the lithium-ion battery of the present invention are not particularly limited, and may include any technology disclosed in the prior art.

[0024] The electrolyte used in the lithium-ion battery of the present invention may also include any technology disclosed in the prior art.

[0025] This invention does not specifically limit the preparation method of lithium-ion batteries; lithium-ion batteries can be prepared using conventional preparation methods in the art. For example, positive electrode sheets, separators, and negative electrode sheets are stacked sequentially, with the separator located between the positive and negative electrode sheets. A cell is obtained through stacking or winding processes, and then the lithium-ion battery of this invention is obtained through baking, electrolyte injection, formation, and packaging.

[0026] Fourthly, the present invention also provides an electrical device including the aforementioned lithium-ion battery.

[0027] It is understood that in the electrical equipment provided by the present invention, the lithium-ion battery can be used as a power source for the electrical equipment, or as an energy storage unit for the electrical equipment. The electrical equipment may be, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0028] The technical solution of this invention has the following advantages: 1. This invention provides an ultra-high nickel cathode material with the general molecular formula LiNi. x Co y M1 a M2 b O2, and x+y+a+b=1, and 0.94≤x<1, 0<y<0.06; where M1 is selected from Zr, Nb, Ti, and the doping amount satisfies a=0.001-0.004; M2 is selected from Al, Mg, and the doping amount satisfies b=0.004-0.012. This invention employs co-doping with a "high-valence strong-bonding element (M1)" and an "anti-misalignment oxygen-stabilizing element (M2)". The high-valence strong-bonding element, with its unique high bond energy, constructs a stable structural support framework within the material's crystal lattice, effectively suppressing drastic changes in lattice parameters caused by lithium-ion insertion / extraction during charging and discharging, significantly reducing the degree of harmful phase transitions, thereby enhancing the material's mechanical strength and structural integrity at the microscopic level. Simultaneously, the anti-misalignment oxygen-stabilizing element, through its unique electronic structure and coordination characteristics, forms stable chemical bonds with lattice oxygen, improving its stability. Furthermore, by preferentially occupying specific lattice sites, it constructs effective spatial barriers, significantly reducing the probability of nickel ion misalignment in the lithium layer. These two elements function in different structural dimensions of the material: the high-valence strong-bonding element primarily stabilizes the material's main framework structure, while the anti-misalignment oxygen-stabilizing element focuses on improving the orderliness and stability of lithium-ion transport channels. Through synergistic effects, they achieve a comprehensive improvement in material performance. The ultra-high nickel cathode material developed in this invention maintains its inherent high capacity while simultaneously achieving significantly improved cycle stability, enhanced thermal safety, and optimized interfacial chemistry, providing a new technological path for the development of high-performance lithium-ion batteries. Furthermore, while achieving these effects, this invention also maximizes the retention of electrochemically active nickel content in the material by controlling the total doping level to a low range.

[0029] 2. The preparation method of ultra-high nickel cathode material provided by the present invention controls the molar ratio of Li:(Ni+Co+M1+M2) in the lithium source and nickel cobalt hydroxide precursor to be 1.02-1.06. An appropriate amount of excess lithium can compensate for lithium volatilization during high-temperature sintering, ensure accurate stoichiometry of the final product, and avoid the aggravation of nickel reduction and cation mixing caused by lithium deficiency. Meanwhile, excess lithium is controlled at a low level, avoiding the formation of a high-resistivity interface layer due to excess lithium salt residue. The two-stage sintering process provided by this invention includes: ① Low-temperature pre-sintering stage (450-550℃): The main purpose of this stage is to allow the lithium source and precursor to undergo a preliminary solid-state reaction, and to decompose and remove crystal water and some volatile components. The slow heating rate and sufficient holding time ensure the uniformity and thoroughness of the reaction, avoiding local overheating and material structural defects caused by rapid heating, laying a good foundation for subsequent high-temperature crystallization; ② High-temperature crystallization stage (740-780℃): This stage is the key process for material lattice reconstruction, crystal growth, and element doping. It is carried out in a pure oxygen atmosphere, which ensures that nickel remains in a high +3 valence state, effectively suppressing cation mixing. Precisely controlled heating rate and holding time promote the formation of a layered structure with good crystallinity, low cation mixing, and uniform distribution of M1 / M2 doping elements.

[0030] 3. The lithium-ion battery and electrical equipment provided by the present invention have the same advantages as the aforementioned ultra-high nickel cathode material due to the use of the ultra-high nickel cathode material provided in this application, which will not be repeated here.

[0031] Additional aspects and advantages of the embodiments of the present invention will be described and shown in part in the following description, or illustrated by practice of the embodiments of this application. Detailed Implementation

[0032] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having” and any variations thereof in the text of this application are intended to cover non-exclusive inclusion.

[0034] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0035] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers from a to b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter can be, for example, integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0036] In the description of the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0037] In the description of the embodiments of this application, the term "at least one" refers to one or more (including two).

[0038] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0039] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0040] Example 1 This embodiment provides a method for preparing an ultra-high nickel cathode material, and the specific steps and parameter settings are as follows: S1, Ni 0.96 Co 0.04 (OH)2, LiOH·H2O (where the molar ratio of lithium to nickel-cobalt transition metals is 1.05), ZrO2, and Al(OH)3 are mixed in a high-speed mixer for 4 hours to obtain a precursor mixture; wherein, based on the total molar amount of transition metals in the final product (1 mol), M1=Zr (0.002mol), M2=Al (0.003mol), and the total doping amount is 0.005mol.

[0041] S2, the precursor mixture was pre-calcined at 500℃ for 6 hours under a pure oxygen atmosphere by heating at 5℃ / min, then sintered at 760℃ for 15 hours by heating at 2℃ / min. After furnace cooling, it was pulverized and passed through a 400-mesh sieve to obtain the ultra-high nickel cathode material LiNi. 0.955 Co 0.040 Zr 0.002 Al 0.003 O2.

[0042] Example 2 This embodiment provides a method for preparing an ultra-high nickel cathode material, and the specific steps and parameter settings are as follows: S1, Ni 0.96 Co 0.04 (OH)2, LiOH·H2O (where the molar ratio of lithium to nickel-cobalt transition metals is 1.05), TiO2, and Al(OH)3 are mixed in a high-speed mixer for 4 hours to obtain a precursor mixture; wherein, based on the total molar amount of transition metals in the final product (1 mol), M1=Ti (0.002mol), M2=Al (0.003mol), and the total doping amount is 0.005mol.

[0043] S2, the precursor mixture was pre-calcined at 500℃ for 6 hours under a pure oxygen atmosphere by heating at 5℃ / min, then sintered at 770℃ for 12 hours by heating at 2℃ / min. After furnace cooling, it was pulverized and passed through a 400-mesh sieve to obtain the ultra-high nickel cathode material LiNi. 0.955 Co 0.040 Ti 0.002 Al 0.003 O2.

[0044] Example 3 This embodiment provides a method for preparing an ultra-high nickel cathode material, and the specific steps and parameter settings are as follows: S1, Ni 0.96 Co 0.04(OH)2, LiOH·H2O (where the molar ratio of lithium to nickel-cobalt transition metals is 1.05), ZrO2, and Mg(OH)2 are mixed in a high-speed mixer for 4 hours to obtain a precursor mixture; wherein, based on the total molar amount of transition metals in the final product (1 mol), M1=Zr (0.001mol), M2=Mg (0.012mol), and the total doping amount is 0.013mol.

[0045] S2, the precursor mixture was pre-calcined at 550℃ for 4 hours under a pure oxygen atmosphere by heating at 2℃ / min, and then sintered at 740℃ for 20 hours by heating at 3℃ / min. After furnace cooling, it was pulverized and passed through a 400-mesh sieve to obtain the ultra-high nickel cathode material LiNi. 0.948 Co 0.039 Zr 0.001 Mg 0.012 O2.

[0046] Example 4 This embodiment provides a method for preparing an ultra-high nickel cathode material, and the specific steps and parameter settings are as follows: S1, Ni 0.96 Co 0.04 (OH)2, LiOH·H2O (where the molar ratio of lithium to nickel-cobalt transition metals is 1.05), Nb2O5, and Al(OH)3 are mixed in a high-speed mixer for 4 hours to obtain a precursor mixture; wherein, based on the total molar amount of transition metals in the final product (1 mol), M1=Nb (0.004mol), M2=Al (0.004mol), and the total doping amount is 0.008mol.

[0047] S2, the precursor mixture was pre-calcined at 450°C for 8 hours under a pure oxygen atmosphere by heating at 5°C / min, then sintered at 780°C for 10 hours by heating at 1°C / min. After furnace cooling, it was pulverized and passed through a 400-mesh sieve to obtain the ultra-high nickel cathode material LiNi. 0.952 Co 0.040 Nb 0.004 Al 0.004 O2.

[0048] Example 5 This embodiment provides a method for preparing an ultra-high nickel cathode material, and the specific steps and parameter settings are as follows: S1, Ni 0.97 Co 0.03(OH)2, LiOH·H2O (where the molar ratio of lithium to nickel-cobalt transition metals is 1.05), ZrO2, and Al(OH)3 are mixed in a high-speed mixer for 4 hours to obtain a precursor mixture; wherein, based on the total molar amount of transition metals in the final product (1 mol), M1=Zr (0.002mol), M2=Al (0.003mol), and the total doping amount is 0.005mol.

[0049] S2, the precursor mixture was pre-calcined at 500℃ for 6 hours under a pure oxygen atmosphere by heating at 5℃ / min, then sintered at 760℃ for 15 hours by heating at 2℃ / min. After furnace cooling, it was pulverized and passed through a 400-mesh sieve to obtain the ultra-high nickel cathode material LiNi. 0.965 Co 0.030 Zr 0.002 Al 0.003 O2.

[0050] Comparative Example 1 This comparative example provides a method for preparing an ultra-high nickel cathode material, with the specific steps and parameter settings as follows: In S1, Ni 0.96 Co 0.04 (OH)2 and LiOH·H2O were mixed in a high-speed mixer for 4 hours to obtain a precursor mixture; S2, the precursor mixture was pre-calcined at 500℃ for 6 hours under a pure oxygen atmosphere by heating at 5℃ / min, then sintered at 760℃ for 15 hours by heating at 2℃ / min. After furnace cooling, it was pulverized and passed through a 400-mesh sieve to obtain the ultra-high nickel ternary cathode material LiNi. 0.96 Co 0.04 O2.

[0051] Comparative Example 2 This comparative example provides a method for preparing an ultra-high nickel cathode material. The only difference from Example 1 is that in S1, based on the total molar amount of transition metal in the final product (1 mol), M2 = Al (0.005 mol), and the total doping amount is 0.005 mol. The remaining steps are the same as in Example 1.

[0052] Comparative Example 3 This comparative example provides a method for preparing an ultra-high nickel cathode material. The only difference from Example 1 is that in S1, based on the total molar amount of transition metal in the final product (1 mol), M1 = Zr (0.005 mol) and the total doping amount is 0.005 mol. The remaining steps are the same as in Example 1.

[0053] Comparative Example 4 This comparative example provides a method for preparing an ultra-high nickel cathode material, with the specific steps and parameter settings as follows: In S1, Ni 0.96 Co 0.04 (OH)2, LiOH·H2O (where the molar ratio of lithium to nickel-cobalt transition metals is 1.05), and Al(OH)3 are mixed in a high-speed mixer for 4 hours to obtain a precursor mixture; wherein, based on the total molar amount of transition metals in the final product (1 mol), M2=Al(0.015mol), and the total doping amount is 0.015mol.

[0054] S2, the precursor mixture was pre-calcined at 500℃ for 6 hours under a pure oxygen atmosphere by heating at 5℃ / min, then sintered at 760℃ for 15 hours by heating at 2℃ / min. After furnace cooling, it was pulverized and passed through a 400-mesh sieve to obtain the ultra-high nickel cathode material LiNi. 0.946 Co 0.039 Al 0.015 O2.

[0055] Comparative Example 5 This comparative example provides a method for preparing an ultra-high nickel cathode material, with the specific steps and parameter settings as follows: S1, Ni 0.96 Co 0.04 Sn(OH)2, LiOH·H2O (where the molar ratio of lithium to nickel-cobalt transition metals is 1.05), ZnO, and Sn(OH)2 are mixed in a high-speed mixer for 4 hours to obtain a precursor mixture; wherein, based on the total molar amount of transition metals in the final product (1 mol), M1=Zn(0.002mol), M2=Sn(0.003mol), and the total doping amount is 0.005mol.

[0056] S2, the precursor mixture was pre-calcined at 500℃ for 6 hours under a pure oxygen atmosphere by heating at 5℃ / min, then sintered at 760℃ for 15 hours by heating at 2℃ / min. After furnace cooling, it was pulverized and passed through a 400-mesh sieve to obtain the ultra-high nickel cathode material LiNi. 0.955 Co 0.040 Zn 0.002 Sn 0.003 O2.

[0057] Comparative Example 6 This comparative example provides a method for preparing an ultra-high nickel cathode material, with the specific steps and parameter settings as follows: S1, Ni 0.96 Co 0.04(OH)2, LiOH·H2O (where the molar ratio of lithium to nickel-cobalt transition metals is 1.05), Nb2O5, Al(OH)3, and Mg(OH)2 are mixed in a high-speed mixer for 4 hours to obtain a precursor mixture; wherein, based on the total molar amount of transition metals in the final product (1 mol), M1=Nb (0.002mol), M2=Al (0.003mol), M3=Mg (0.003mol), and the total doping amount is 0.008mol.

[0058] S2, the precursor mixture was pre-calcined at 500℃ for 6 hours under a pure oxygen atmosphere by heating at 5℃ / min, then sintered at 760℃ for 15 hours by heating at 2℃ / min. After furnace cooling, it was pulverized and passed through a 400-mesh sieve to obtain the ultra-high nickel cathode material LiNi. 0.952 Co 0.040 Nb 0.002 Al 0.003 Mg 0.003 O2.

[0059] Experimental Example 1 The performance of the ultra-high nickel cathode materials prepared in each embodiment and comparative example was tested. The specific test methods are as follows: The particle size of the ultra-high nickel cathode material was tested using a laser particle size analyzer (Mastersizer 3000). A small amount of sample was dispersed in a medium, ultrasonically dispersed, and then injected into the sample cell of the instrument for testing. The D50 value was used as the average particle size. The cation mixing of the ultra-high nickel cathode material was tested using an X-ray diffractometer (Bruck D8, Germany). Step scans (0.02° increments) were performed on the sample, and data for the (003) and (104) diffraction peaks were collected. Cation mixing was determined by calculating the intensity ratio of the (003) to (104) diffraction peaks. I (003) / (104) To evaluate; The residual alkali content on the surface of the ultra-high nickel cathode material was determined by acid-base titration. First, in a CO2-free environment, soluble lithium salts in the sample were precisely leached using decarbonated water or ethanol aqueous solution. Then, the leaching solution was titrated and analyzed, and an automatic potentiometric titrator was used to monitor pH jumps in order to distinguish and quantitatively calculate the contents of LiOH and Li2CO3.

[0060] The specific test data is shown in Table 1.

[0061] Table 1 Performance data of high-nickel ternary modified cathode materials

[0062] As shown in Table 1, the cation mixing ratio of the cathode materials prepared in Examples 1-5 is in the range of 1.45-1.60, which is higher than that of the comparative example (1.20-1.32). This indicates that the co-doping of specific amounts of M1 and M2 effectively suppressed Ni 2+ To Li + The migration of sites demonstrates that M1 and M2 have a significant synergistic enhancement effect in suppressing cation mixing. The low degree of cation mixing provides a smooth channel for the rapid diffusion of lithium ions, which is the basis for obtaining excellent rate performance and cycle performance.

[0063] The residual alkali content on the surface of the cathode materials prepared in Examples 1-5 ranged from 0.9 wt% to 1.2 wt%, all lower than the 1.3 wt% to 2.5 wt% of the comparative examples. This significant reduction in residual alkali demonstrates that the specific co-doping scheme effectively stabilized the lattice oxygen on the material surface, reducing reactions with CO2 and H2O in the air during high-rate sintering. Lower residual alkali content means fewer interfacial side reactions and lower gas generation rate during battery cycling, directly contributing to better cycle life and higher battery safety.

[0064] Experiment Example 2 The ultra-high nickel cathode materials prepared in each embodiment and comparative example were applied to lithium-ion batteries, and then their electrical performance was tested.

[0065] The method for preparing the lithium-ion battery includes the following steps: The active material, acetylene black, and polyvinylidene fluoride (PVDF) were mixed in N-methylpyridinium ketone (NMP) at a mass ratio of 8:1:1 to obtain a uniform slurry. This slurry was then coated onto aluminum foil (20 μm thick) using a 300 μm doctor blade and dried in a vacuum drying oven without rolling. The dried aluminum foil was then sliced ​​into Ф1.3 cm discs using a slicer. The assembly of the button half-cell was carried out in an argon-filled glove box with a water content below 0.5 ppm. The electrolyte consisted of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 1:1. A CR2032 type button half-cell was assembled in the following order: negative electrode, electrolyte, separator, electrolyte, and positive electrode.

[0066] The assembled button half-cells were subjected to thermal runaway initiation temperature and cycle performance tests at 25°C. (1) Thermal runaway initiation temperature test The thermal runaway initiation temperature of the lithium-ion battery was determined using the adiabatic accelerated calorimetry method in GB / T 36276-2023 "Lithium-ion Batteries for Power Storage".

[0067] (2) Cyclic performance test In the first cycle, the lithium-ion battery was charged at 0.2C to 4.25V under a constant temperature environment of 25℃, and then charged at a constant voltage of 4.25V until the current cutoff was 0.05C. After resting for 5 minutes, it was discharged at 0.2C to 2.7V.

[0068] In the second cycle, under a constant temperature environment of 25°C, the lithium-ion battery was charged at 1C to 4.25V, and then charged at a constant voltage of 4.25V until the current cutoff was 0.05C. After resting for 5 minutes, it was discharged at 1C to 2.7V. This method was repeated 500 times, and the capacity retention rate was recorded.

[0069] The specific test data is shown in Table 2.

[0070] Table 2 Lithium-ion battery performance data

[0071] As shown in Table 2, the rational dual-element doping system significantly improves the overall electrochemical performance and safety characteristics of the high-nickel cathode material. Compared with the undoped (Comparative Example 1) or single-element doped (Comparative Examples 2-3), Example 1 (dual-element doping) exhibits a higher thermal runaway initiation temperature and better long-cycle stability. This is mainly due to the lower surface residual alkali content and higher cation ordering. The low residual alkali effectively reduces interfacial side reactions and improves thermal stability; while the reduced cation mixing degree helps maintain structural integrity during cycling. Further comparison reveals that the selection and combination of doping elements are crucial for performance balance. Although Comparative Example 4 (single high-dose Al doping) achieved the highest thermal runaway temperature (235℃), its first-cycle capacity and cycle retention were lower than most examples, indicating that single doping may come at the cost of capacity and some cycle performance. Examples 1-5, through the rational combination of Zr / Ti / Nb and Al / Mg, achieved the best balance between safety, first-cycle efficiency, and cycle performance while maintaining high capacity. This indicates that through dual-element synergistic modification, the overall battery performance of high-nickel cathode materials can be comprehensively improved without excessively sacrificing any single indicator.

[0072] Furthermore, Comparative Example 5 (Zn-Sn doping) suffered from the most severe cation mixing and the highest residual alkali due to improper element selection, which comprehensively deteriorated the thermal safety and cycle life of the battery, demonstrating the decisive role of the intrinsic chemical properties of the doping elements. Comparative Example 6 (Nb-Al-Mg ternary doping) failed to exert its synergistic advantages due to excessive and unbalanced doping, and its overall performance was inferior to the optimized two-element system, indicating that modification is not simply a matter of adding element types.

[0073] In summary, the "M1 + M2" co-doped ultra-high nickel cathode material provided by this invention successfully solves the key technical bottlenecks inherent in ultra-high nickel materials, such as high cation mixing, high surface residual alkali, poor thermal stability, and rapid cycle life decay, through ingenious design and synergistic effects between elements. Experimental data fully demonstrate that this invention achieves significant improvements in key performance indicators through synergy rather than simple additive effects, thus providing a lithium-ion battery cathode material solution that combines high energy density, high safety, and long lifespan, and promoting the commercial application of ultra-high nickel cathode materials.

[0074] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An ultra-high nickel cathode material, characterized in that, Its general molecular formula is LiNi x Co y M1 a M2 b O2, and x+y+a+b=1, and 0.94≤x<1, 0<y<0.06; M1 is selected from one of Zr, Nb, and Ti, and the doping amount satisfies a = 0.001-0.004; M2 is selected from Al or Mg, and the doping amount satisfies b = 0.004-0.

012.

2. The ultra-high nickel cathode material according to claim 1, characterized in that, M1 is Zr, M2 is Al, and the doping amounts of M1 and M2 satisfy a+b=0.

005.

3. The ultra-high nickel cathode material according to claim 1 or 2, characterized in that, The ultra-high nickel cathode material comprises polycrystalline secondary spherical particles constructed from primary grains at the nanoscale or submicron scale; Optionally, the particle size of the polycrystalline secondary spherical particles is 7-14 μm.

4. The ultra-high nickel cathode material according to any one of claims 1-3, characterized in that, The cation mixing of the ultra-high nickel cathode material I (003) / (104) >1.4; And / or, the surface residual alkali content of the ultra-high nickel cathode material is <1.2wt%.

5. A method for preparing the ultra-high nickel cathode material according to any one of claims 1-4, characterized in that, Includes the following steps: S1, a precursor mixture is obtained by mixing a nickel-cobalt hydroxide precursor, a lithium source, a compound containing element M1, and a compound containing element M2. S2, after two-stage sintering of the precursor mixture, it is crushed and sieved to obtain ultra-high nickel cathode material.

6. The preparation method according to claim 5, characterized in that, The two-stage sintering process includes heating to 450-550℃ at a rate of 2-5℃ / min and holding for 4-8h in a pure oxygen atmosphere, and heating to 740-780℃ at a rate of 1-3℃ / min and holding for 10-20h. And / or, the molar ratio of Li:(Ni+Co+M1+M2) in the lithium source and the nickel-cobalt hydroxide precursor is 1.02-1.

06.

7. The preparation method according to claim 5 or 6, characterized in that, The compounds containing the M1 element include one of ZrO2, Nb2O5, and TiO2; And / or, the compound containing the M2 element includes one of Al(OH)3 and Mg(OH)2; And / or, the lithium source includes one of LiOH·H2O and Li2CO3.

8. The preparation method according to any one of claims 5-7, characterized in that, The general formula of the nickel-cobalt hydroxide precursor includes Ni x Co y (OH)2, where 0.94≤x<1.

9. A lithium-ion battery, characterized in that, This includes the ultra-high nickel cathode material according to any one of claims 1-4 or the ultra-high nickel cathode material prepared by the preparation method according to any one of claims 5-8.

10. An electrical appliance, characterized in that, Including the lithium-ion battery as described in claim 9.

Images