High-nickel single crystal positive electrode material, preparation method therefor, positive electrode sheet, secondary battery and electrical apparatus

Abstract

A high-nickel single crystal positive electrode material, a preparation method therefor, a positive electrode sheet, a secondary battery and an electrical apparatus. The chemical formula of the high-nickel single crystal positive electrode material is Li1+δNixMyQ1-x-yO2+εAαRβXγ, wherein 0.8≤x＜1, 0＜y≤0.2, 0≤δ≤0.15, 0＜ε≤0.2, 0＜α≤0.04, 0＜β≤0.04, 0≤γ≤0.04, the element M and element Q each independently comprise one or more of Mn, Co, Al, Ta, Ti, Nb, Ge, Y, Nb, W, Zr, Ce, Ca, Sr, Sc, V, Cr and Mo, the element A comprises one or more of Mg, Ca, Sr, Ba, Ti, Zr, V, Nb, Ta, Mo, W, La, Ce, Sc and Cr, the element R comprises one or more of B and P, and the element X comprises one or more of Na, K, Mn, Mg, Ca, Sr and Al. The molar ratio of surface Ni3+ in the high-nickel single crystal positive electrode material is 38%-55%, and the molar ratio of surface lattice oxygen is 7%-15%. The material has obviously reduced structural defects, thus improving the specific capacity thereof, and improving the cycle performance thereof.

Description

High nickel single crystal positive electrode material and preparation method thereof, positive electrode sheet, secondary battery and electrical device

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 29, 2024, with application number 202410120099.2 and invention name “High nickel single crystal positive electrode material and preparation method thereof, positive electrode sheet, secondary battery and electrical device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the technical field of sodium ion batteries, and in particular to a high-nickel single crystal positive electrode material and a preparation method thereof, a positive electrode sheet, a secondary battery and an electrical device. Background Art

[0003] New energy vehicles are increasingly being used, with lithium-ion batteries as their power source being the core component. The cathode material is a crucial factor in lithium-ion battery systems. Among existing cathode material systems, high-nickel single-crystal cathode materials offer advantages such as high specific capacity, high compaction density, and high surface / structural stability, making them widely used in the preparation of lithium-ion batteries. However, the preparation of high-nickel single-crystal cathode materials requires relatively high sintering temperatures to ensure that the primary particles fully grow and separate into a single crystal form. Due to the poor high-temperature stability of high-nickel single-crystal cathode materials, the resulting material suffers from both specific capacity and cycling performance.

[0004] Summary of the Invention

[0005] Based on this, the present application provides a high nickel single crystal positive electrode material with high specific capacity and excellent cycle performance, a preparation method thereof, a positive electrode sheet, a secondary battery and an electrical device.

[0006] The first aspect of the present application provides a high nickel single crystal positive electrode material, the chemical formula of which is Li 1+δ Ni x M y Q 1-x-y O 2+ε A α R β X γ, 0.8 ≤ x < 1, 0 < y ≤ 0.2, 0 ≤ δ ≤ 0.15, 0 < ε ≤ 0.2, 0 < α ≤ 0.04, 0 < β ≤ 0.04, 0 ≤ γ ≤ 0.04, the M element and the Q element each independently include one or more of Mn, Co, Al, Ta, Ti, Nb, Ge, Y, W, Zr, Ce, Ca, Sr, Sc, V, Cr, and Mo; the A element includes one or more of Mg, Ca, Sr, Ba, Ti, Zr, V, Nb, Ta, Mo, W, La, Ce, Sc, and Cr; the R element includes one or more of B and P; the X element includes one or more of Na, K, Mn, Mg, Ca, Sr, and Al; the Ni on the surface of the high-nickel single-crystal cathode material 3+ has a molar ratio of 38% - 55%, and the molar ratio of the surface lattice oxygen is 7% - 15%. <00000⑨4><00000⑨5>In some embodiments, for the primary particles of the high-nickel single-crystal cathode material, the length is denoted as L, the width is denoted as W, and W / L is 0.7 - 0.85; <00000⑨6><00000⑨7>Optionally, L is 1300 nm - 2000 nm; <00000⑨8><00000⑨9>Optionally, W is 900 nm - 1500 nm.

[0010] In some embodiments, in the XRD pattern of the high-nickel single-crystal cathode material, the diffraction peak intensities I (003) and I (104) between satisfy the following relationship: 1.3 ≤ I (003) / I (104) ≤ 2.

[0011] The second aspect of the present application provides a preparation method of the high-nickel single-crystal cathode material of the first aspect of the present application, including the following steps:

[0012] [[ID=Z8]]Prepare a local oxygen replenishing flux including a basic flux component and an oxidizing component; the oxidizing component can generate an oxidizing gas under heating conditions; the elements contained in the basic flux component include the A element and the R element, and the elements contained in the oxidizing component include the X element;

[0013] Perform presintering treatment on a powder mixture including a lithium source and a precursor to prepare a presintered material; the chemical formula of the precursor is Ni c M d Q 1-c-d (OH)₂, 0.8 ≤ c < 1, 0 < d ≤ 0.2, the M element and the Q element each independently include one or more of Mn, Co, Al, Ta, Ti, Nb, Ge, Y, W, Zr, Ce, Ca, Sr, Sc, V, Cr, and Mo;

[0014] The local oxygen supplement flux and the pre-sintered material are mixed and placed in a sample container for sintering to prepare the high-nickel single crystal positive electrode material;

[0015] The mass of the local oxygen supplement flux accounts for 0.1%-4% of the mass of the pre-sintered material.

[0016] In some embodiments, the oxidizing component comprises one or more of peroxides, superoxides, nitrates, nitrites, hypochlorites, chlorates, perchlorates, manganates, and permanganates of a Z element, wherein the Z element comprises one or more of Li, Na, K, Mg, Ca, Sr, and Al; and / or

[0017] The basic flux components include one or more of a type A flux and a type B flux; the type A flux includes one or more of oxides, hydroxides, carbonates, sulfates, chlorides and lithium oxygen compounds containing element A, and the element A includes one or more of Mg, Ca, Sr, Ba, Ti, Zr, V, Nb, Ta, Mo, W, La, Ce, Sc and Cr; the type B flux includes one or more of oxyacids and oxyacid salts containing boron or phosphorus;

[0018] Optionally, the ratio of the total molar amount of the A element, the boron element and the phosphorus element contained in the basic flux component to the total molar amount of the Z element contained in the oxidizing component is (0.5-1.5):1.

[0019] In some embodiments, the pre-sintering process includes at least one of the following conditions (1)-(6):

[0020] (1) The lithium source includes one or more of lithium hydroxide monohydrate, anhydrous lithium hydroxide, lithium carbonate, lithium nitrate, lithium oxide, lithium oxalate, lithium fluoride, lithium chloride, lithium acetate, lithium sulfate and lithium phosphate;

[0021] (2) The total molar ratio of the lithium element contained in the lithium source to the metal element contained in the precursor is (0.95-1.20):1, and can be optionally (1.01-1.11):1;

[0022] (3) The temperature of the pre-sintering treatment is 500°C-700°C, and can be optionally 600°C-700°C;

[0023] (4) The pre-sintering treatment time is 2h-7h, and can be optionally 4h-6h;

[0024] (5) The heating rate of the pre-sintering treatment is 2°C / min-20°C / min, and can be optionally 3°C / min-10°C / min;

[0025] (6) The atmosphere of the pre-sintering treatment includes one or more of air and oxygen, and air can be selected.

[0026] In some embodiments, the sintering process includes at least one of the following conditions (1)-(6):

[0027] (1) The stacking depth of the pre-burned material in the sample container is 1 cm-30 cm, and can be optionally 8 cm-20 cm;

[0028] (2) The mass of the local oxygen supplement flux accounts for 0.3%-1.8% of the mass of the pre-sintered material;

[0029] (3) The sintering temperature is 700°C-1000°C, and can be optionally 750°C-850°C;

[0030] (4) The sintering time is 6 hours to 20 hours, and can be optionally 10 hours to 14 hours;

[0031] (5) The heating rate of the pre-sintering treatment is 2°C / min-15°C / min, and can be optionally 3°C / min-10°C / min;

[0032] (6) The atmosphere of the sintering treatment includes one or more of air and oxygen, and air can be selected.

[0033] The third aspect of the present application provides a positive electrode plate, comprising the high-nickel single crystal positive electrode material of the first aspect of the present application or the high-nickel single crystal positive electrode material prepared by the preparation method of the second aspect of the present application.

[0034] The fourth aspect of the present application provides a secondary battery, comprising the positive electrode sheet of the third aspect of the present application.

[0035] A fifth aspect of the present application provides an electrical device comprising the secondary battery of the fourth aspect of the present application.

[0036] The high nickel single crystal positive electrode material provided above has a surface Ni 3+ The molar proportion is as high as 38%-55%, and the molar proportion of surface lattice oxygen is 7%-15%. During the preparation process, nickel reduction and lattice oxygen precipitation are significantly inhibited, and the structural defects of the material are significantly reduced, thereby increasing its specific capacity and improving its cycle performance.

[0037] In the preparation method of the high-nickel single crystal positive electrode material provided by the present application, the local oxygen supplementation flux used not only has the basic functions of conventional fluxes such as promoting particle growth, adjusting crystal planes and morphology, and reducing sintering temperature, but also contains a component that is oxidizing and can be decomposed at high temperatures. During the sintering process, the local high oxidizing environment generated by its decomposition can be used to further inhibit nickel reduction and lattice oxygen precipitation, so that the obtained high-nickel single crystal positive electrode material has the advantages of reduced defects, optimized particle morphology and crystal structure, and improved electrochemical performance. At the same time, because the local oxygen supplementation flux reduces the sintering temperature, and its local oxygen supplementation characteristics alleviate the problem of insufficient oxygen supply to the material at the bottom of the sample container, the amount of material loaded in a single sintering can be further increased, thereby achieving the effect of improving production efficiency and reducing costs.

[0038] In addition, the amount of local oxygen supplement flux is limited to a range equivalent to that of the doping and coating agents, and no additional washing process is required; it does not contain precious metal elements and other high-priced transition metal elements, making the additive cost of this method controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application and to more fully understand the present application and its beneficial effects, the following is a brief introduction to the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present application. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0040] FIG1 is a SEM image of the high nickel single crystal positive electrode material in Example 1;

[0041] FIG2 is an XRD pattern of the high nickel single crystal positive electrode material in Example 1;

[0042] FIG3 is a detailed spectrum of Ni2p and O1s in Example 1 and Comparative Example 1;

[0043] FIG4 is a charge and discharge curve of Example 1;

[0044] FIG5 is a cycle performance diagram of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0045] To facilitate understanding of the present invention, the present application will be described more fully below with reference to the relevant embodiments. The following provides preferred embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0047] The terms "and / or", "or / and", and "and / or" used herein include any one of two or more related listed items, and also include any and all combinations of the related listed items, wherein the any and all combinations include any combination of two related listed items, any more related listed items, or all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", and "and / or", it should be understood that in this application, the technical solution undoubtedly includes technical solutions connected by "logical AND" and technical solutions connected by "logical OR".

[0048] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0049] In this application, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0050] Only certain numerical ranges are specifically disclosed herein. However, any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and similarly, any upper limit may be combined with any other upper limit to form an unspecified range. In addition, each individually disclosed point or single value may itself serve as a lower limit or upper limit and be combined with any other point or single value, or with other lower limits or upper limits, to form an unspecified range.

[0051] The temperature parameters in this application, unless otherwise specified, allow for both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows for temperature fluctuations within the precision range of instrument control. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are permitted.

[0052] In this application, unless otherwise specified, the references to size, particle size, and diameter generally refer to average values. In this application, "particle size" and "particle diameter" have the same meaning, both representing the average particle size of spheres or spheroids.

[0053] Herein, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc. shall be based on the ability to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0054] In this application, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be understood as limiting the scope of protection of this application.

[0055] In this application, the terms "optionally," "optional," and "optional" mean optional or dispensable, i.e., they refer to either option being selected from two parallel options: "with" or "without." If a technical solution contains multiple "optional" clauses, each "optional" clause is independent unless otherwise specified and there are no contradictions or constraints.

[0056] In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0057] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution. Unless otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0058] Unless otherwise specified, all steps of the present application can be performed sequentially or randomly, preferably sequentially.

[0059] When preparing high-nickel single-crystal positive electrode materials, in order to allow the primary particles to fully grow and separate to form a single crystal form, a higher sintering temperature is required during the preparation process. As a result, the unstable LiNiO2 structure in the high-nickel layered material undergoes lattice oxygen precipitation accompanied by nickel reduction during the sintering process, leading to structural defects such as cation mixing and inactive phase transition in the crystal structure, which has an adverse effect on the specific capacity and cycle life of the material.

[0060] Currently, the measures commonly taken in the industry to alleviate the defect problems of high-nickel single-crystal materials are as follows: (1) Lowering the sintering temperature: Using an appropriate flux to reduce the sintering temperature, thereby inhibiting the precipitation of lattice oxygen in the high-nickel single-crystal materials and the induced structural defects; (2) Ensuring sufficient oxygen supply: Using a pure oxygen atmosphere and restricting the charging depth during the sintering process to ensure that oxygen can diffuse to the bottom of the crucible, increasing the local oxygen concentration, enabling the material to fully contact with oxygen, promoting the shift of chemical equilibrium, and thus inhibiting the precipitation of lattice oxygen. However, measure (2) will result in limited charging quantity per single sintering, which is不利 to improving production capacity and reducing costs.

[0061] When using common fluxes in measure (1), the problem of insufficient oxygen supply and limited charging depth for the material at the bottom of the crucible cannot be solved. Instead, it may further hinder the diffusion of oxygen to the bottom of the crucible due to the formation of eutectics in the top material.

[0062] Based on the above problems, this application studies process parameters such as flux components, addition amounts, and material charging quantities in the crucible, and prepares a high-nickel single-crystal cathode material with reduced structural defects, improved particle morphology and crystal structure, and enhanced electrical properties.

[0063] The first aspect of this application provides a high-nickel single-crystal cathode material, and the chemical formula of the high-nickel single-crystal cathode material is Li 1+δ Ni x M y Q 1-x-y O 2+ε A α R β X γ , 0.8 ≤ x < 1, 0 < y ≤ 0.2, 0 ≤ δ ≤ 0.15, 0 < ε ≤ 0.2, 0 < α ≤ 0.04, 0 < β ≤ 0.04, 0 ≤ γ ≤ 0.04. The M element and the Q element each independently include one or more of Mn, Co, Al, Ta, Ti, Nb, Ge, Y, W, Zr, Ce, Ca, Sr, Sc, V, Cr, and Mo; the A element includes one or more of Mg, Ca, Sr, Ba, Ti, Zr, V, Nb, Ta, Mo, W, La, Ce, Sc, and Cr; the R element includes one or more of B and P; the X element includes one or more of Na, K, Mn, Mg, Ca, Sr, and Al; the molar ratio of Ni 3+ on the surface of the high-nickel single-crystal cathode material is 38% - 55%, and the molar ratio of lattice oxygen on the surface is 7% - 15%.

[0064] As an example, the molar ratio of Ni 3+ It should be noted that the "不利" in the original text is not a standard Chinese word. I assume it might be a misspelling and translated it as "不利" which may need to be further confirmed according to the correct Chinese expression.The molar percentage may be, but is not limited to, 38%, 38.5%, 39%, 39.5%, 40%, 40.5%, 41%, 41.5%, 42%, 42.5%, 43%, 43.5%, 44%, 44.5%, 45%, 45.5%, 46%, 46.5%, 47%, 47.5%, 48%, 48.5%, 49%, 49.5%, 50%, 50.5%, 51%, 51.5%, 52%, 52.5%, 53%, 53.5%, 54%, 54.5%, 55%, or a range between any two of the above values.

[0065] The molar fraction of surface lattice oxygen of the high nickel single crystal positive electrode material can be but is not limited to 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15% or a range between any two of the above values.

[0066] Understandably, the surface Ni 3+ The molar proportion is as high as 38%-55%, and the molar proportion of surface lattice oxygen is 7%-15%. During the preparation process, nickel reduction and lattice oxygen precipitation are significantly inhibited, and the structural defects of the material are significantly reduced, thereby increasing its specific capacity and improving its cycle performance.

[0067] It should be noted that the surface Ni of the high nickel single crystal positive electrode material mentioned above 3+ The molar proportion and the molar proportion of surface lattice oxygen can be measured by X-ray photoelectron spectroscopy (XPS). The measurement process can be specifically as follows: Al-Kα is used as the radiation source (energy hν = 1486.6eV), and the C1s peak binding energy of 284.80eV is used as the charge correction standard; the Ni 2p and O 1s two sets of fine spectra are further analyzed, and deconvolution is performed according to the unified characteristic peak position to obtain the relative proportions of the following chemical states, based on Ni 3+ / (Ni 3+ +Ni 2+ ), O 吸附 / (O 吸附 +O 晶格 )Calculation of surface Ni 3+ molar proportion and molar proportion of surface lattice oxygen; and through Ni 3+ / (Ni 3+ +Ni 2+ ) ratio, O 吸附 / (O 吸附 +O 晶格 ) reflects the degree of nickel reduction and lattice oxygen precipitation.

[0068] In some embodiments, the length of the primary particles of the high-nickel single crystal positive electrode material is recorded as L, the width is recorded as W, and W / L is 0.7-0.85; for example, it can be but is not limited to 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, or a range between any two of the above values. When the ratio of length L to width W is within the above range, it indicates that the particle morphology of the high-nickel single crystal positive electrode material is optimized, which is beneficial to improving the reversible capacity and cycle stability of the material.

[0069] It should be noted that the primary particles of the high-nickel single crystal positive electrode material are converted into rectangles with equal area and closest shape, where the long side of the rectangle is length L and the short side is width W.

[0070] In some optional embodiments, the length L of the primary particles of the high-nickel single crystal positive electrode material is between 1300 nm and 2000 nm; for example, it can be, but is not limited to, 1300 nm, 1350 nm, 1400 nm, 1450 nm, 1500 nm, 1550 nm, 1600 nm, 1650 nm, 1700 nm, 1750 nm, 1800 nm, 1850 nm, 1900 nm, 1950 nm, 2000 nm, or a range between any two of the foregoing lengths. When the length L is within the foregoing range, the high-nickel single crystal positive electrode material particles have an appropriate contact area with the electrolyte, which is sufficient for lithium ion insertion / extraction reactions while avoiding excessive surface side reactions, thereby improving the cycle performance of the battery.

[0071] As one possible embodiment, the length L of the primary particles of the high-nickel single crystal positive electrode material is 900 nm to 1500 nm; for example, it can be, but is not limited to, 900 nm, 950 nm, 1000 nm, 1050 nm, 1100 nm, 1150 nm, 1200 nm, 1250 nm, 1300 nm, 1350 nm, 1400 nm, 1450 nm, 1500 nm, or a range between any two of the foregoing lengths. When the width W is within the above range, the high-nickel single crystal positive electrode material particles have an appropriate contact area with the electrolyte, which is sufficient for lithium ion insertion / extraction reactions while avoiding excessive surface side reactions, thereby improving the battery's cycling performance.

[0072] As an example, the length L, width W, and width-to-length ratio W / L of the primary particles of the high-nickel single crystal positive electrode material mentioned above can be measured using a field emission scanning electron microscope.

[0073] In some embodiments, in the XRD pattern of the high nickel single crystal positive electrode material, the diffraction peak intensity I of the crystal plane (003) and the crystal plane (104) is (003) and I(104) satisfies the following relational expression: 1.3 ≤ I (003) / I (104) ≤ 2. As an example, I (003) / I (104) can be, but is not limited to, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, or the range between any two of the above values, etc. I (003) / I (104) within the above range indicates that the crystal structure of the high-nickel single-crystal cathode material is effectively optimized, which is beneficial to improving the reversible capacity and cycle stability of the material.

[0074] It should be noted that the above-mentioned I (003) and I (104) can be measured by powder X-ray diffraction. The specific measurement process can be as follows: Use Cu-Kα ray as the ray source, its wavelength is 0.154 nm (the Kα2 is not removed from the test data), the accelerating voltage and current are 40 kV and 100 mA respectively, scan at a rate of 5° / min within the range of 10° - 80°, and calculate the area ratio I (003) / I (104) .

[0075] The second aspect of the present application provides a preparation method of the high-nickel single-crystal cathode material of the first aspect of the present application, including the following steps:

[0076] Prepare a local oxygen-supplemented flux including a basic flux component and an oxidizing component; the oxidizing component can generate an oxidizing gas under heating conditions; the elements contained in the basic flux component include element A and element R, and the elements contained in the oxidizing component include element X;

[0077] Perform presintering treatment on the powder mixture including a lithium source and a precursor to prepare a presintered material; the chemical formula of the precursor is Ni c M d Q 1-c-d (OH)2, 0.8 ≤ c < 1, 0 < d ≤ 0.2, element M and element Q each independently include one or more of Mn, Co, Al, Ta, Ti, Nb, Ge, Y, W, Zr, Ce, Ca, Sr, Sc, V, Cr, and Mo;

[0078] Mix the local oxygen-supplemented flux and the presintered material and place them in a sample container, and perform sintering treatment to prepare the high-nickel single-crystal cathode material; wherein, the mass of the local oxygen-supplemented flux accounts for 0.1% - 4% of the mass of the presintered material.

[0079] It should be noted that the basic flux component is a substance that has the functions of promoting particle growth, adjusting particle shape, and reducing sintering temperature. Adding the basic flux during the preparation process can promote particle growth, adjust particle shape, and reduce sintering temperature.

[0080] Understandably, the applied local oxygen-supplementing flux not only has the basic functions of conventional fluxes, such as promoting particle growth, adjusting crystal planes and morphology, and reducing sintering temperatures, but also contains an oxidizing component that can decompose at high temperatures. During the sintering process, the local high-oxidizing environment generated by its decomposition can be used to further inhibit nickel reduction and lattice oxygen precipitation, so that the resulting high-nickel single crystal positive electrode material has the advantages of reduced defects, optimized particle morphology and crystal structure, and improved electrochemical performance. At the same time, because the local oxygen-supplementing flux reduces the sintering temperature, and its local oxygen-supplementing characteristics alleviate the problem of insufficient oxygen supply to the material at the bottom of the sample container, the amount of material loaded in a single sintering can be further increased, achieving the effect of improving production efficiency and reducing costs.

[0081] In addition, the amount of local oxygen supplement flux is limited to a range equivalent to that of the doping and coating agents, and no additional washing process is required; it does not contain precious metal elements and other high-priced transition metal elements, making the additive cost of this method controllable.

[0082] As an example, the mass percentage of the local oxygen supplementation flux to the mass of the pre-sintered material can be, but is not limited to, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or a range between any two of the above values. When the amount of the local oxygen supplementation flux is within the above range, it can decompose and generate oxidizing gas during the sintering process, solving the problem that oxygen is difficult to diffuse to the surface of the material (especially the material at the bottom of the container), providing it with sufficient oxygen concentration, effectively inhibiting nickel reduction and lattice oxygen precipitation, reducing defects, optimizing particle morphology and crystal structure, and improving electrochemical performance; on the other hand, it can also avoid the problem of reduced electrochemical performance due to excessive electrochemically inert residues.

[0083] As an example, during sintering, the mass percentage of the local oxygen supplement flux to the mass percentage of the pre-sintered material can be, but is not limited to, 0.4%-1.8%, 0.8%-1.8%, 1.2%-1.8%, 0.4%-1.2%, 0.8%-1.2% or 0.4%-0.8%.

[0084] As a possible embodiment, the basic flux components include one or more of Class A flux and Class B flux; Class A flux includes one or more of oxides, hydroxides, carbonates, sulfates, chlorides and lithium oxygen compounds containing element A, and element A includes one or more of Mg, Ca, Sr, Ba, Ti, Zr, V, Nb, Ta, Mo, W, La, Ce, Sc and Cr; Class B flux includes one or more of oxygen-containing acids and oxygen-containing acid salts containing boron or phosphorus.

[0085] In some embodiments, the ratio of the total molar amount of the A element, the boron element, and the phosphorus element contained in the basic flux component to the total molar amount of the Z element contained in the oxidizing component is (0.5-1.5):1; for example, it can be, but is not limited to, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, or ranges between any two of the above ratios. Thus, the basic flux component and the oxidizing component in the local oxygen supplementation flux are both contained in appropriate ratios, respectively playing the above-mentioned roles, thereby achieving the beneficial effects of reducing the sintering temperature and improving the electrochemical performance.

[0086] In some optional embodiments, the oxidizing component includes one or more of peroxides, superoxides, nitrates, nitrites, hypochlorites, chlorates, perchlorates, manganates and permanganates of Z elements, wherein the Z elements include one or more of Li, Na, K, Mg, Ca, Sr and Al.

[0087] In some embodiments, when the pre-sintering treatment is performed, the lithium source includes one or more of lithium hydroxide monohydrate, anhydrous lithium hydroxide, lithium carbonate, lithium nitrate, lithium oxide, lithium oxalate, lithium fluoride, lithium chloride, lithium acetate, lithium sulfate, and lithium phosphate.

[0088] In some exemplary embodiments, during the pre-sintering process, the molar ratio of the lithium element contained in the lithium source to the total metal elements contained in the precursor is (0.95-1.20):1; for example, it can be, but is not limited to, 0.95:1, 0.97:1, 1:1, 1.03:1, 1.05:1, 1.08:1, 1.1:1, 1.13:1, 1.15:1, 1.18:1, 1.2:1, or a range between any two of the above ratios. Optionally, the molar ratio of the lithium element contained in the lithium source to the total metal elements contained in the precursor is (1.01-1.11):1.

[0089] In some embodiments, when the pre-sintering treatment is performed, the pre-sintering temperature is 500°C-700°C; for example, it can be but not limited to 500°C, 530°C, 550°C, 570°C, 600°C, 630°C, 650°C, 680°C, 700°C, or a range between any two of the above temperatures. Optionally, the pre-sintering temperature is 600°C-700°C. When the pre-sintering temperature is within the above range, the moisture in the material can be fully removed in advance, increasing its density, thereby increasing the material loading capacity and yield of the subsequent sintering process, thereby increasing production capacity. Optionally, the pre-sintering temperature is 600°C-700°C.

[0090] As a possible embodiment, when performing the pre-sintering treatment, the pre-sintering treatment time is 2 hours to 7 hours; for example, it can be but not limited to 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, or a range between any two of the above times. Optionally, the pre-sintering treatment time is 4 hours to 6 hours.

[0091] In some optional embodiments, during the pre-sintering process, the heating rate of the pre-sintering process is 2°C / min-20°C / min; for example, it can be, but is not limited to, 2°C / min, 5°C / min, 7°C / min, 10°C / min, 13°C / min, 15°C / min, 18°C / min, 20°C / min, or a range between any two of the above heating rates. Optionally, the heating rate of the pre-sintering process is 3°C / min-10°C / min.

[0092] In some embodiments, the atmosphere of the pre-sintering process includes one or more of air and oxygen. Optionally, the atmosphere of the pre-sintering process is air.

[0093] As an example, the air is dry air.

[0094] It should be noted that the temperature, time, heating rate and atmosphere of the pre-sintering treatment can be combined in any appropriate manner, and the four can be selected from any pre-sintering treatment temperature, time, heating rate and atmosphere described herein.

[0095] In some embodiments, during the sintering process, the stacking depth of the pre-calcined material in the sample container is 1 cm to 30 cm, thereby increasing the sample loading capacity, thereby improving production efficiency and reducing costs. As an example, the stacking depth can be, but is not limited to, 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, 11 cm, 12 cm, 13 cm, 14 cm, 15 cm, 16 cm, 17 cm, 18 cm, 19 cm, 20 cm, 21 cm, 22 cm, 23 cm, 24 cm, 25 cm, 26 cm, 27 cm, 28 cm, 29 cm, 30 cm, or a range between any two of the above depths.

[0096] In some embodiments, during the sintering process, the stacking depth of the material after the local oxygen supplementation flux and the pre-sintered material are mixed in the sample container is 1 cm-30 cm, thereby increasing the sample loading capacity, thereby improving production efficiency and reducing costs. As an example, the stacking depth can be, but is not limited to, 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, 11 cm, 12 cm, 13 cm, 14 cm, 15 cm, 16 cm, 17 cm, 18 cm, 19 cm, 20 cm, 21 cm, 22 cm, 23 cm, 24 cm, 25 cm, 26 cm, 27 cm, 28 cm, 29 cm, 30 cm, or a range between any two of the above depths.

[0097] As an example, the stacking depth of the calcined material in the sample container may be, but is not limited to, 9 cm-18 cm, 12 cm-18 cm, 6 cm-18 cm, 6 cm-12 cm, 6 cm-9 cm, or 9 cm-12 cm.

[0098] As an example, the stacking depth of the mixed material of the local oxygen supplement flux and the pre-burned material in the sample container can be but is not limited to 9cm-18cm, 12cm-18cm, 6cm-18cm, 6cm-12cm, 6cm-9cm or 9cm-12cm, etc.

[0099] Optionally, the pre-burned material is stacked to a depth of 8 cm to 20 cm in the sample container. Further, optionally, the pre-burned material is stacked to a depth of 9 cm to 18 cm in the sample container. More optionally, the pre-burned material is stacked to a depth of 12 cm to 18 cm in the sample container.

[0100] Optionally, the mixture of the local oxygen-supplementing flux and the pre-burned material has a stacking depth of 8 cm to 20 cm in the sample container. Further, optionally, the mixture of the local oxygen-supplementing flux and the pre-burned material has a stacking depth of 9 cm to 18 cm in the sample container. Even more optionally, the mixture of the local oxygen-supplementing flux and the pre-burned material has a stacking depth of 12 cm to 18 cm in the sample container.

[0101] During the sintering process, compared with the case where no oxidizing components are added, by adding a local oxygen supplement flux, defects can be reduced by inhibiting the precipitation of lattice oxygen. Under the premise that the sintered products have the same degree of defects (surface nickel valence ratio, lattice oxygen ratio, (003) / (104) peak intensity ratio), the raw material stacking depth can be increased by 5cm-12cm, thereby improving production efficiency. When the stacking depth is ≥8cm, compared with the case where no oxidizing components are added, the surface Ni calculated by analyzing the X-ray photoelectron spectroscopy (XPS) data is 3+ The molar ratio increases by 5%-20 percentage points, and the molar ratio of surface lattice oxygen increases by 2%-10%.

[0102] As a possible implementation, the sample container is a sagger.

[0103] In some optional embodiments, during the sintering process, the mass of the local oxygen supplement flux accounts for 0.3%-1.8% of the mass of the pre-sintered material.

[0104] As a possible embodiment, during the sintering process, the sintering temperature is 700°C-1000°C; for example, it can be, but is not limited to, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, or a range between any two of the foregoing temperatures. When the sintering temperature is within this range, the primary particles can fully grow and separate to form a single crystal form, with the particle size within the above range, and nickel reduction and lattice oxygen precipitation caused by excessively high sintering temperatures can be avoided. Optionally, the sintering temperature is 750°C-850°C.

[0105] As an example, when the sintering treatment is performed, the sintering temperature may be 800° C.-840° C., 800° C.-820° C., or 820° C.-840° C., etc., without specific limitation.

[0106] It should be noted that compared with not adding local oxygen flux, when other conditions are the same, adding local oxygen flux can reduce the sintering temperature by 50℃-100℃ through its effects of promoting growth and regulating growth direction, and optimize the particle morphology and crystal structure of high-nickel single crystal materials, improve their reversible capacity and cycle stability, and reduce processing costs.

[0107] In some optional embodiments, the sintering time is 6-20 hours; for example, but not limited to, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, or a range between any two of the above times. When the sintering time is within the above range, the primary particles can fully grow and separate into a single crystal form, with the particle size within the above range. Optionally, the sintering time is 10-14 hours.

[0108] In some exemplary embodiments, during the sintering process, the heating rate of the sintering process is 2°C / min-15°C / min. For example, the heating rate may be, but is not limited to, 2°C / min, 5°C / min, 7°C / min, 10°C / min, 13°C / min, 15°C / min, or a range between any two of the above heating rates. Optionally, the heating rate of the sintering process is 3°C / min-10°C / min.

[0109] In some embodiments, the sintering atmosphere includes one or more of air and oxygen. Alternatively, the sintering atmosphere is air. Further, optionally, the sintering atmosphere is dry air.

[0110] It should be noted that the temperature, time, heating rate and atmosphere of the sintering treatment can be combined in any appropriate manner, and the four can be selected from any sintering treatment temperature, time, heating rate and atmosphere described in this article.

[0111] The third aspect of the present application provides a positive electrode plate, comprising the high-nickel single crystal positive electrode material of the first aspect or the high-nickel single crystal positive electrode material prepared by the preparation method of the second aspect.

[0112] A fourth aspect of the present application provides a secondary battery comprising the positive electrode sheet of the third aspect.

[0113] The secondary battery of the present application comprises the above-mentioned high-nickel single crystal positive electrode material, and has a high specific capacity and excellent cycle performance.

[0114] The fifth aspect of the present application provides an electrical device comprising the secondary battery of the fourth aspect. The electrical device may be an electric vehicle, an electric bicycle, an electric two-wheeled vehicle, an electric vehicle power system, an energy storage system, or a mobile storage device, without limitation.

[0115] The electric device of the present application includes the secondary battery provided by the present application, and thus has at least the same advantages as the secondary battery.

[0116] The technical solutions of the present invention are described in detail below with reference to specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. For experimental methods in the following examples where specific conditions are not specified, reference should be made to the instructions provided in the present invention, or to experimental manuals or conventional conditions in the art, or to conditions recommended by the manufacturer, or to experimental methods known in the art.

[0117] In the following specific examples, the measured parameters of raw material components may have slight deviations within the range of weighing accuracy unless otherwise specified. For temperature and time parameters, acceptable deviations caused by instrument testing accuracy or operational accuracy are allowed.

[0118] 1. Preparation of high nickel single crystal cathode materials

[0119] Example 1

[0120] Step S1. Weigh the basic flux components Sr(OH)2, H3BO3, (NH4)2HPO4 and the oxidizing components Li2O2, LiClO4, and calculate the amount according to the atomic molar ratio of Sr, B, P, Li, and Li being 1:1:1:2:2, and mix them evenly to obtain a local oxygen supplement flux.

[0121] Step S2. Weigh 913.31g of lithium source LiOH·H2O and 1933.58g of precursor Ni according to the total molar ratio of lithium element in the lithium source to metal elements contained in the precursor of 1.06:1. 0.9 Co 0.05 Mn 0.05 (OH)2 was stirred in a mixing device at 3000 rpm for 4 minutes to obtain a uniformly mixed material, which was then placed in a sagger and placed in a sintering furnace for pre-sintering. The pre-sintered product was crushed to obtain a pre-sintered material. The pre-sintering temperature was 625°C for 6 hours at a heating rate of 3°C / min. The pre-sintering atmosphere was dry compressed air at an air flow rate of 3 L / min.

[0122] Step S3. Add a local oxygen flux at a concentration of 0.8% of the pre-sintered material. Stir and mix in a mixing device at 2000 rpm for 4 minutes. The mixture is then dispensed into appropriately sized saggers to a depth of 12 cm. The saggers are placed in a sintering furnace for sintering to produce a high-nickel single crystal positive electrode material. The sintering parameters are: 820°C for 10 hours, a heating rate of 5°C / min, a pure oxygen atmosphere (oxygen content ≥ 97%), and a gas flow rate of 4 L / min. The sintered product is crushed and screened to obtain the final product. Physical and chemical characterization and electrochemical performance testing are performed.

[0123] Example 2

[0124] The difference between Example 2 and Example 1 is that the temperature of the sintering treatment in step S3 is 800° C., and the other aspects are the same.

[0125] Example 3

[0126] The difference between Example 3 and Example 1 is that the temperature of the sintering treatment in step S3 is 840° C., and the other aspects are the same.

[0127] Example 4

[0128] The difference between Example 4 and Example 3 is that the mass of the local oxygen supplement flux added in step S3 is 1.2% of the pre-sintered material, and the other aspects are the same.

[0129] Example 5

[0130] The difference between Example 5 and Example 3 is that the mass of the local oxygen supplement flux added in step S3 is 0.4% of the pre-sintered material, and the other aspects are the same.

[0131] Example 6

[0132] The difference between Example 6 and Example 1 is that the depth of the material in the sagger in step S3 is 9 cm, and the other aspects are the same.

[0133] Example 7

[0134] The difference between Example 7 and Example 1 is that the depth of the material in the sagger in step S3 is 6 cm, and the other aspects are the same.

[0135] Example 8

[0136] The difference between Example 8 and Example 1 is that in step S1, the basic flux components BaCO3, TiO2, and LiBO2 and the oxidizing components LiNO3 and NaNO3 are weighed, and the amounts thereof are calculated so that the atomic molar ratio of Ba, Ti, B, Li, and Na is 1:1:1:2:2, and the mixture is uniformly mixed to obtain a local oxygen supplement flux. All other steps are the same.

[0137] Example 9

[0138] Example 9 differs from Example 1 in that: Step S1. The basic flux components Mg(OH)2, ZrO2, and Li3PO4, and the oxidizing components KMnO4 and NaClO4 are weighed, with the amounts calculated so that the atomic molar ratio of Mg, Zr, P, K, and Na is 1:1:1:2:2, and the mixture is uniformly mixed to obtain a local oxygen-supplementing flux. All other steps are the same.

[0139] Example 10

[0140] Example 10 differs from Example 1 in that: Step S1. The basic flux components Sr(OH)2, H3BO3, (NH4)2HPO4 and the oxidizing components Li2O2 and Na2O2 are weighed and used in amounts calculated such that the atomic molar ratio of Sr, B, P, Li, and Na is 1:1:1:2:2, and the mixture is uniformly mixed to obtain a local oxygen supplement flux. All other steps are the same.

[0141] Example 11

[0142] Example 11 differs from Example 1 in that: Step S1. The basic flux components Sr(OH)2, H3BO3, (NH4)2HPO4 and the oxidizing components Li2O2 and LiNO3 are weighed and used in amounts calculated such that the atomic molar ratio of Sr, B, P, Li, and Li is 1:1:1:2:2, and the mixture is uniformly mixed to obtain a local oxygen supplement flux. All other steps are the same.

[0143] Example 12

[0144] The difference between Example 12 and Example 1 is that the mass of the local oxygen supplement flux added in step S3 is 1.8% of the pre-burned material, and the other aspects are the same.

[0145] Example 13

[0146] The difference between Example 13 and Example 1 is that the depth of the material in the sagger in step S3 is 18 cm, and the other aspects are the same.

[0147] Comparative Example 1

[0148] The difference between Comparative Example 1 and Example 1 is that no flux is added in step S3 and the sintering temperature is 880° C. The other aspects are the same.

[0149] Comparative Example 2

[0150] The difference between Comparative Example 2 and Example 1 is that no oxidizing component is added when preparing the flux in step S1, the sintering temperature in step S3 is 840° C., and the depth of the material in the sagger is 12 cm. All other conditions are the same.

[0151] Comparative Example 3

[0152] The difference between Comparative Example 3 and Example 1 is that no oxidizing component is added when preparing the flux in step S1, the sintering temperature in step S3 is 840° C., and the depth of the material in the sagger is 6 cm. All other conditions are the same.

[0153] Comparative Example 4

[0154] The difference between Comparative Example 4 and Example 1 is that no oxidizing component is added when preparing the flux in step S1. All other steps are the same.

[0155] Comparative Example 5

[0156] The difference between Comparative Example 5 and Example 1 is that no oxidizing component is added when preparing the flux in step S1, and the temperature of the sintering treatment in step S3 is 800° C. All other aspects are the same.

[0157] Comparative Example 6

[0158] The difference between Comparative Example 6 and Example 1 is that the mass of the local oxygen supplement flux added in step S3 is 5.0% of the pre-sintered material, and the other aspects are the same.

[0159] 2. Characterization of cathode material morphology, size and crystal structure

[0160] The positive electrode material was observed using a field emission scanning electron microscope, and the length L and width W of each visible primary particle were measured and counted for the micrographs of appropriate magnification (the particles were converted into rectangles of equal area and closest shape, with the long side of the rectangle being the length L and the short side being the width W) and the ratio W / L between the two was calculated. The test results of Examples 1-11 and Comparative Examples 1-5 are shown in Table 1. The results of the scanning electron microscope observation of Example 1 are shown in Figure 1. As can be seen from Figure 1, the primary particles of the high nickel single crystal positive electrode material obtained in Example 1 have fully grown to a suitable size range and separated.

[0161] The cathode material was tested using a powder X-ray diffractometer. Cu-Kα radiation was used as the radiation source with a wavelength of 0.154 nm (Kα2 was not removed from the test data). The acceleration voltage and current were 40 kV and 100 mA, respectively. The scanning rate was 5° / min within the range of 10°-80°. The area ratio of the (003) peak to the (104) peak in the obtained curve was calculated. (003) / I (104) . The test results of Examples 1-11 and Comparative Examples 1-5 are shown in Table 1. The XRD spectrum of Example 1 is shown in Figure 2. As can be seen from Figure 2, the high-nickel single crystal positive electrode material prepared in Example 1 has a typical α-NaFeO2 layered crystal structure, belongs to the hexagonal crystal system, R-3m space group, and the two strongest diffraction peaks are the (003) crystal plane peak near 18.7° and the (104) crystal plane peak near 44.3°.

[0162] Table 1

[0163] 3. Surface chemical valence test of cathode materials

[0164] The cathode material was tested using an X-ray photoelectron spectrometer (XPS). Al-Kα was used as the radiation source (energy hν = 1486.6 eV) and the C1s peak binding energy of 284.80 eV was used as the charge correction standard. The Ni2p and O1s fine spectra were further analyzed and deconvoluted according to the unified characteristic peak position to obtain the following relative proportions of the chemical states: 2+ 、Ni 3+ , O 吸附 , O 晶格 The characteristic peak positions of Ni are defined as 855.1±0.1eV, 856.5±0.1eV, 531.6±0.1eV, and 529.0±0.1eV, respectively. 3+ / (Ni 3+ +Ni 2+ ) ratio, O 吸附 / (O 吸附 +O 晶格 ) reflects the degree of nickel reduction and lattice oxygen precipitation, and the results are shown in Table 2. The Ni 2p and O 1s fine spectra of Example 1 and Comparative Example 1 are shown in Figure 3. Figure 3 (a) shows the Ni 2p fine spectra of Example 1 and Comparative Example 1, and Figure 3 (b) shows the O 1s fine spectra of Example 1 and Comparative Example 1.

[0165] Table 2

[0166] From the results in Table 2, it can be seen that the surface Ni 3+ The molar proportions are all higher than those of comparative examples 1-5. At the same time, the molar proportions of surface lattice oxygen in the embodiments are generally higher than those in the comparative examples, indicating that the local oxygen supplementation flux plays a role in inhibiting nickel reduction and oxygen precipitation, especially when the material depth is large.

[0167] In Comparative Example 6, the surface Ni 3+ The molar proportion of oxygen is the highest, while the molar proportion of surface lattice oxygen is the lowest. The possible reason is that excessive addition of local oxygen supplement flux leads to excessive amount of surface attachment (reflected as adsorbed oxygen in the O1s spectrum of XPS), which increases the relative proportion of adsorbed oxygen in the test results and reduces the relative proportion of lattice oxygen.

[0168] 4. Electrochemical performance test

[0169] The positive electrode material was mixed with PVDF binder, conductive carbon black and N-methylpyrrolidone solvent in a mass ratio of 100:4.3:3.8:137 to form a uniform slurry and evenly coated on one side of the aluminum foil. After drying, compacting and punching, the positive electrode sheet of the button battery was made (the compaction density was 3.2g / cm 3), and lithium sheets as the positive and negative electrodes, respectively, were assembled into button cells, wherein the electrolyte was a 1M LiPF6 (EC / DMC, volume ratio of 1:1) solution. Charge-discharge capacity and cycle performance tests were conducted at room temperature in the voltage range of 3.0V-4.3V. The results are shown in Table 3. The charge-discharge curve of Example 1 is shown in Figure 4. The cycle performance results of Example 1 and Comparative Example 1 are shown in Figure 5.

[0170] Table 3

[0171] From the results in Tables 1-3, it can be seen that the high nickel single crystal positive electrode material provided by this application has a high surface Ni 3+ The molar proportion and the surface lattice oxygen molar proportion are 38%-55% and 7%-15%, respectively. The lengths L and W of the primary particles of the material satisfy 0.7≤W / L≤0.85. The ratio of the diffraction peak intensity of the crystal plane (003) and the crystal plane (104) in the XRD pattern of the material is I (003) / I (104) It is 1.3-2; that is, the structural defects of the high nickel single crystal positive electrode material are significantly reduced, the particle morphology and crystal structure are significantly improved, and the reversible capacity and cycle stability are significantly improved.

[0172] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0173] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A high nickel single crystal positive electrode material, characterized in that: The chemical formula of the high-nickel single-crystal cathode material is Li 1+δ Ni x M y Q 1-x-y O 2+ε A α R β X γ , 0.8 ≤ x < 1, 0 < y ≤ 0.2, 0 ≤ δ ≤ 0.15, 0 < ε ≤ 0.2, 0 < α ≤ 0.04, 0 < β ≤ 0.04, 0 ≤ γ ≤ 0.

04. The M element and the Q element each independently include one or more of Mn, Co, Al, Ta, Ti, Nb, Ge, Y, W, Zr, Ce, Ca, Sr, Sc, V, Cr, and Mo; the A element includes one or more of Mg, Ca, Sr, Ba, Ti, Zr, V, Nb, Ta, Mo, W, La, Ce, Sc, and Cr; the R element includes one or more of B and P; the X element includes one or more of Na, K, Mn, Mg, Ca, Sr, and Al; the molar ratio of Ni 3+ on the surface of the high-nickel single-crystal cathode material is 38% - 55%, and the molar ratio of lattice oxygen on the surface is 7% - 15%.

2. The high nickel single crystal cathode material according to claim 1, characterized in that The length of the primary particles of the high nickel single crystal positive electrode material is recorded as L, the width is recorded as W, and W / L is 0.7-0.85; Optionally, L is 1300nm-2000nm; Optionally, W is 900nm-1500nm.

3. The high nickel single crystal positive electrode material according to any one of claims 1 to 2, characterized in that In the XRD spectrum of the high nickel single crystal positive electrode material, the diffraction peak intensity I of the crystal plane (003) and the crystal plane (104) is (003) and I (104) The following relationship is satisfied: 1.3≤I (003) / I (104) ≤2.

4. A method for preparing a high-nickel single crystal positive electrode material according to any one of claims 1 to 3, characterized in that: The steps include: A local oxygen supplement flux is prepared comprising a basic flux component and an oxidizing component; the oxidizing component can generate an oxidizing gas under heating conditions; the elements contained in the basic flux component include the A element and the R element, and the elements contained in the oxidizing component include the X element; The powder mixture including a lithium source and a precursor is subjected to a pre-sintering treatment to prepare a pre-sintered material; the chemical formula of the precursor is Ni c M d Q 1-c-d (OH)2, 0.8 ≤ c < 1, 0 < d ≤ 0.2, and the M element and the Q element each independently include one or more of Mn, Co, Al, Ta, Ti, Nb, Ge, Y, W, Zr, Ce, Ca, Sr, Sc, V, Cr, and Mo; The local oxygen supplement flux and the pre-sintered material are mixed and placed in a sample container for sintering to prepare the high-nickel single crystal positive electrode material; The mass of the local oxygen-supplementing flux accounts for 0.1%-4% of the mass of the pre-sintered material.

5. The preparation method according to claim 4, wherein The oxidizing component comprises one or more of peroxides, superoxides, nitrates, nitrites, hypochlorites, chlorates, perchlorates, manganates and permanganates of a Z element, wherein the Z element comprises one or more of Li, Na, K, Mg, Ca, Sr and Al; and / or The basic flux components include one or more of a type A flux and a type B flux; the type A flux includes one or more of oxides, hydroxides, carbonates, sulfates, chlorides and lithium oxygen compounds containing the element A, and the element A includes one or more of Mg, Ca, Sr, Ba, Ti, Zr, V, Nb, Ta, Mo, W, La, Ce, Sc and Cr; the type B flux includes one or more of oxyacids and oxyacid salts containing boron or phosphorus; Optionally, the ratio of the total molar amount of the A element, the boron element and the phosphorus element contained in the basic flux component to the total molar amount of the Z element contained in the oxidizing component is (0.5-1.5):

1.

6. The preparation method according to any one of claims 4 to 5, characterized in that The pre-sintering treatment includes at least one of the following conditions (1)-(6): (1) The lithium source includes one or more of lithium hydroxide monohydrate, anhydrous lithium hydroxide, lithium carbonate, lithium nitrate, lithium oxide, lithium oxalate, lithium fluoride, lithium chloride, lithium acetate, lithium sulfate and lithium phosphate; (2) The total molar ratio of the lithium element contained in the lithium source to the metal element contained in the precursor is (0.95-1.20):1, and can be optionally (1.01-1.11):1; (3) The temperature of the pre-sintering treatment is 500°C-700°C, and can be optionally 600°C-700°C; (4) The pre-sintering treatment time is 2h-7h, and can be optionally 4h-6h; (5) The heating rate of the pre-sintering treatment is 2°C / min-20°C / min, and can be optionally 3°C / min-10°C / min; (6) The atmosphere of the pre-sintering treatment includes one or more of air and oxygen, and air can be selected.

7. The preparation method according to any one of claims 4 to 5, characterized in that The sintering process includes at least one of the following conditions (1) to (6): (1) The stacking depth of the pre-burned material in the sample container is 1 cm-30 cm, and can be optionally 8 cm-20 cm; (2) The mass of the local oxygen supplement flux accounts for 0.3%-1.8% of the mass of the pre-sintered material; (3) The sintering temperature is 700°C-1000°C, and can be optionally 750°C-850°C; (4) The sintering time is 6 hours to 20 hours, and can be optionally 10 hours to 14 hours; (5) The heating rate of the pre-sintering treatment is 2°C / min-15°C / min, and can be optionally 3°C / min-10°C / min; (6) The atmosphere of the sintering treatment includes one or more of air and oxygen, and air can be selected.

8. A positive electrode plate, characterized in that: The invention comprises the high-nickel single crystal positive electrode material according to any one of claims 1 to 3 or the high-nickel single crystal positive electrode material prepared by the preparation method according to any one of claims 4 to 7.

9. A secondary battery, characterized in that: Comprising the positive electrode sheet as claimed in claim 8.

10. An electrical device, characterized in that: Comprising the secondary battery as claimed in claim 9.

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