Single-crystal high-nickel ternary positive electrode material, preparation method, positive electrode sheet and lithium ion battery

Abstract

The application relates to a single-crystal high-nickel ternary positive electrode material, a preparation method, a positive electrode sheet and a lithium ion battery, and the preparation method comprises the following steps: mixing a first lithium source, a nickel salt, a manganese salt and a cobalt salt to obtain a lithium-containing metal salt solution; performing spray pyrolysis on the lithium-containing metal salt solution to obtain a lithium-containing oxide precursor; mixing the lithium-containing oxide precursor with a second lithium source, and performing sintering to obtain the single-crystal high-nickel ternary positive electrode material; and in the lithium-containing metal salt solution, the molar ratio of the content of lithium to the total amount of nickel, cobalt and manganese is (0.65-0.75):1. In the application, the lithium source and the nickel, cobalt and manganese source are mixed in a solution, and a lithium-containing oxide precursor with atomic-level uniform distribution of lithium, nickel, cobalt and manganese is obtained by using a spray pyrolysis process, the number and uniformity of ordered superlattice structures in the lithium-containing oxide precursor are improved, the mixing of anions and cations in the sintering process is reduced, the release of lattice oxygen is reduced, and the structural stability of the single-crystal high-nickel ternary positive electrode material is improved.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to high-nickel cathode materials, and more particularly to a single-crystal high-nickel ternary cathode material, its preparation method, cathode sheet, and lithium-ion battery. Background Technology

[0002] High-nickel ternary cathode materials, with their significant advantages of high theoretical specific capacity and low cobalt content, have become a core direction for developing high-energy-density lithium-ion power batteries. However, increasing the nickel content significantly exacerbates the lithium-nickel mixing phenomenon, leading to a decrease in material structural stability and a simultaneous deterioration in specific capacity and rate performance. Furthermore, during the preparation of high-nickel ternary cathode materials, the mixing effect of anions and cations is further intensified when the high-nickel ternary precursor and lithium source are mixed and calcined, inducing lattice oxygen release and forming numerous lattice defects, ultimately severely affecting the material's structural stability and cycle performance.

[0003] CN113066978A discloses a Ta-doped high-nickel single-crystal cathode material and its preparation method. This invention utilizes tantalum surface doping to reduce the surface concentration of Ginger-Taylor effect ions, suppressing transition metal dissolution and increasing lithium-ion migration speed, thus improving the specific capacity and rate performance of the cathode material. Furthermore, the Ta-O bond energy is higher than the Ni-O bond energy, which can significantly suppress oxygen evolution under high voltage and improve battery cycle performance. The higher Ta-O bond energy also helps stabilize the interface and reduce oxygen release problems under high voltage. Finally, after high-temperature sintering, the tantalum oxide reacts chemically with residual lithium on the surface to form the ionic conductor lithium tantalate, which can both isolate the electrolyte from the cathode material and provide lithium-ion conductivity.

[0004] CN121565853A discloses a multi-element differentially distributed co-doped single-crystal high-nickel cathode material, its preparation method, and its applications. By designing a gradient enrichment of the first dopant element in the near-surface region of the particle and a uniform distribution of the second dopant element in the bulk phase of the particle, a multi-element co-doped structure with spatially differential distribution is constructed. This effectively blocks the electrolyte from eroding the active material, suppresses interfacial side reactions, and fundamentally inhibits lithium-nickel mixing and harmful phase transitions during charge and discharge. Furthermore, this synergistic mechanism of surface protection and bulk stability significantly reduces the charge transfer impedance and ohmic impedance of the material, and improves the lithium-ion diffusion coefficient, thereby simultaneously improving the cycle stability and rate performance of the material.

[0005] CN113764658A discloses a high-nickel single-crystal ternary cathode material co-doped with cations and anions, its preparation method, and its applications. By replacing oxygen sites in the high-nickel single-crystal ternary cathode material with anions, excessive oxidation of lattice oxygen can be suppressed at high potentials, alleviating lattice oxygen loss. It can also eliminate superoxide radicals generated during lattice oxygen oxidation, alleviating electrolyte decomposition caused by superoxide radicals. Ultimately, this synergistically suppresses capacity decay and voltage drop of the high-nickel single-crystal cathode material during cycling. By replacing transition metal sites of nickel, cobalt, and manganese in the high-nickel single-crystal ternary cathode material with cations, the crystal structure can be stabilized during charge and discharge, increasing the oxygen vacancy formation energy and suppressing the generation of microcracks, thereby improving cycle stability and thermal stability. In addition, cation doping can also induce lattice defects, improve intrinsic conductivity, and improve rate performance.

[0006] Currently, while common modification methods such as element doping and surface coating can alleviate the above problems to some extent, the process from precursor preparation to final cathode material forming is lengthy and has a long cycle, which not only increases the production cost but may also trigger side reactions, leading to reversible capacity decay of the cathode material.

[0007] Therefore, it is of great significance to provide a single-crystal high-nickel ternary cathode material with high structural stability and its efficient synthesis method. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a single-crystal high-nickel ternary cathode material, its preparation method, cathode sheet, and lithium-ion battery. The present invention mixes lithium and nickel-cobalt-manganese sources in a solution and utilizes a spray pyrolysis process to complete the oxidative decomposition of the solution in a very short time, obtaining a lithium-containing oxide precursor with atomically uniform distribution of lithium and nickel-cobalt-manganese. This increases the number and uniformity of ordered superlattice structures in the lithium-containing oxide precursor, thereby reducing the mixing of anions and cations during sintering, minimizing the release of lattice oxygen, and improving the structural stability of the single-crystal high-nickel ternary cathode material.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for preparing a single-crystal high-nickel ternary cathode material, the method comprising:

[0011] A lithium-containing metal salt solution is obtained by mixing a first lithium source, nickel salt, manganese salt, and cobalt salt; the lithium-containing metal salt solution is subjected to spray pyrolysis to obtain a lithium-containing oxide precursor; the lithium-containing oxide precursor is mixed with a second lithium source and sintered to obtain the single-crystal high-nickel ternary cathode material; in the lithium-containing metal salt solution, the molar ratio of lithium content to total nickel, cobalt, and manganese is (0.65~0.75):1.

[0012] This invention mixes lithium and nickel-cobalt-manganese sources in a solution, achieving atomic-level uniform mixing of lithium and nickel-cobalt-manganese in a lithium-containing metal salt solution. Then, using a spray pyrolysis process, the solution is oxidized and decomposed in a very short time to obtain a lithium-containing oxide precursor with atomically uniform distribution of lithium and nickel-cobalt-manganese. A stable and ordered lattice structure is effectively constructed in the precursor, increasing the number and uniformity of ordered superlattice structures in the lithium-containing oxide precursor. The ordered crystal structure can effectively bind lattice oxygen, reducing the mixing of anions and cations during sintering from the source, reducing the release of lattice oxygen, and improving the structural stability of the single-crystal high-nickel ternary cathode material.

[0013] Furthermore, this invention utilizes spray pyrolysis, a highly efficient process for synthesizing ternary precursor oxides, which significantly improves the preparation efficiency and material performance consistency of single-crystal high-nickel ternary cathode materials.

[0014] Preferably, the molar ratio of lithium content in the second lithium source to the total amount of nickel, cobalt, and manganese in the lithium oxide precursor is (0.35~0.45):1.

[0015] Preferably, the total concentration of nickel, cobalt, and manganese in the lithium-containing metal salt solution is 200 g / L to 300 g / L.

[0016] Preferably, the temperature of the spray pyrolysis is 700℃~900℃.

[0017] Preferably, the sintering temperature is 800℃~900℃.

[0018] Preferably, the sintering time is 8h to 15h.

[0019] Preferably, in the lithium-containing metal salt solution, the molar ratio of nickel, cobalt, and manganese is (0.8~0.95):(0~0.2):(0~0.2).

[0020] Preferably, the first lithium salt comprises a soluble lithium salt, which includes any one or a combination of at least two of lithium nitrate, lithium chloride, or lithium acetate.

[0021] Preferably, the second lithium salt comprises any one or a combination of at least two of lithium nitrate, lithium chloride, lithium acetate, lithium oxide, or lithium hydroxide.

[0022] In a second aspect, the present invention provides a single-crystal high-nickel ternary cathode material, which is obtained by the preparation method described in the first aspect.

[0023] Thirdly, the present invention provides a positive electrode sheet, the positive electrode sheet comprising the single-crystal high-nickel ternary positive electrode material as described in the second aspect.

[0024] Fourthly, the present invention provides a lithium-ion battery comprising a single-crystal high-nickel ternary cathode material as described in the second aspect, or a cathode sheet as described in the third aspect.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) In this invention, lithium source and nickel cobalt manganese source are mixed in solution and spray pyrolysis process is used to complete the oxidation decomposition of solution in a very short time to obtain lithium oxide precursor with uniform atomic distribution of lithium and nickel cobalt manganese. This increases the number and uniformity of ordered super lattice structure in lithium oxide precursor, thereby reducing the mixing of anions and cations during sintering, reducing the release of lattice oxygen, and improving the structural stability of single crystal high nickel ternary cathode material.

[0027] (2) This invention utilizes spray pyrolysis, a highly efficient process for synthesizing ternary precursor oxides, which reduces the preparation cost of ternary precursors, shortens the preparation steps, and significantly improves the preparation efficiency and material performance consistency of single-crystal high-nickel ternary cathode materials. Detailed Implementation

[0028] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0029] The scope of this invention can be defined by lower and upper limits. The selected lower and upper limits define the boundaries of a specific range. The range defined in this way can be defined by the inclusion or exclusion of endpoints. Any endpoint can be independently selected for inclusion or exclusion, and all lower and upper limits can be arbitrarily combined to form new ranges. That is, any lower limit can be combined with any upper limit to form an effective range. For example, if the ranges of 60~120 and 80~110 are listed for specific parameters, it should be understood that the ranges of 60~110 and 80~120 also fall within the scope of this invention. In addition, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are also listed, then all ranges of 1~3, 1~4, 1~5, 2~3, 2~4 and 2~5 fall within the scope of this invention. In this invention, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between 0 and 5 have been fully listed in this document, and "0~5" is only a shortened representation of this set of numerical combinations. When a parameter is expressed as an integer ≥2, it is equivalent to listing positive integers that meet the requirements, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. When a parameter is expressed as an integer selected from "2~10", it is equivalent to listing any integer among 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0030] In this invention, "a combination of at least two" refers to a quantity greater than or equal to 2 unless otherwise specified. For example, "any one or a combination of at least two" means that any one of the listed items can be selected, or a combination of at least two of the listed items formed in a manner that does not conflict and enables the implementation of this invention. In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" cover any one of two or more related listed items, as well as any and all combinations of the related listed items. The arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" means a set consisting of A, B, and combinations of A and B, where "containing A and / or B" can be understood, depending on the context of the statement, as containing A, containing B, or simultaneously containing both A and B. In this invention, "optional" means that the corresponding feature, component, step or solution is not necessary, that is, it is selected from either "with" or "without". If there are multiple "optional" limitations in a technical solution, unless otherwise specified and there is no technical conflict or mutual constraint, each "optional" limitation is independent and does not affect the others.

[0031] In this invention, technical features or solutions described using open-ended terms such as "comprising" or "including" do not exclude additional non-conflicting elements beyond the listed elements unless otherwise specified. They are considered to disclose both closed-ended features or solutions consisting solely of the listed elements and open-ended features or solutions that may include additional non-conflicting elements beyond the listed elements. For example, if A includes a1, a2, and a3, unless otherwise specified, this means that A can consist only of a1, a2, and a3, or it can include other non-conflicting elements based on a1, a2, and a3. This corresponds to the disclosure of technical solutions such as "A consists of a1, a2, and a3," "A is selected from a1, a2, and a3," and "A not only includes a1, a2, and a3, but may also include other non-conflicting elements." All embodiments and optional embodiments of this invention, unless otherwise specified and without technical conflict, can be combined to form new technical solutions, and such combinations fall within the scope of this invention. The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various locations throughout the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this invention can be combined with other embodiments that do not conflict with the technology. The ordinal numbers "first," "second," "third," and "fourth," etc., used in the expressions "first aspect," "second aspect," "third aspect," and "fourth aspect" in this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly specifying the importance or quantity of the indicated technical features. They serve only as a non-exhaustive enumeration and do not constitute a closed limitation on quantity.

[0032] In this invention, the order in which the steps are written in the methods described in each embodiment does not imply a strict execution order. The actual execution order of each step should be determined based on its function and possible internal logic. Unless otherwise specified, all steps of this invention can be executed in the order they are written, or in any order without technical conflict. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) executed sequentially, or it may include steps (b) and (a) executed sequentially. If the method also includes step (c), then step (c) can be added to the method in any order without conflict, including but not limited to the execution order of steps (a), (b), and (c), steps (a), (c), and (b), steps (c), (a), and (b), etc.

[0033] In one specific embodiment, the present invention provides a method for preparing a single-crystal high-nickel ternary cathode material, the method comprising:

[0034] A lithium-containing metal salt solution is obtained by mixing a first lithium source, nickel salt, manganese salt, and cobalt salt; the lithium-containing metal salt solution is subjected to spray pyrolysis to obtain a lithium-containing oxide precursor; the lithium-containing oxide precursor is mixed with a second lithium source and sintered to obtain the single-crystal high-nickel ternary cathode material; in the lithium-containing metal salt solution, the molar ratio of lithium content to total nickel, cobalt, and manganese is (0.65~0.75):1.

[0035] This invention mixes lithium and nickel-cobalt-manganese sources in a solution, achieving atomic-level uniform mixing of lithium and nickel-cobalt-manganese in a lithium-containing metal salt solution. Then, using a spray pyrolysis process, the solution is oxidized and decomposed in a very short time to obtain a lithium-containing oxide precursor with atomically uniform distribution of lithium and nickel-cobalt-manganese. A stable and ordered lattice structure is effectively constructed in the precursor, increasing the number and uniformity of ordered superlattice structures in the lithium-containing oxide precursor. The ordered crystal structure can effectively bind lattice oxygen, reducing the mixing of anions and cations during sintering from the source, reducing the release of lattice oxygen, and improving the structural stability of the single-crystal high-nickel ternary cathode material.

[0036] Furthermore, this invention utilizes spray pyrolysis, a highly efficient process for synthesizing ternary precursor oxides, which significantly improves the preparation efficiency and material performance consistency of single-crystal high-nickel ternary cathode materials.

[0037] This invention regulates the molar ratio of lithium content to total nickel, cobalt, and manganese in the lithium-containing metal salt solution to (0.65~0.75):1, for example, 0.65:1, 0.67:1, 0.69:1, 0.7:1, 0.71:1, 0.73:1, or 0.75:1. This regulates the quantity and uniformity of ordered superlattice structures in the lithium oxide precursor, effectively confining lattice oxygen during sintering while ensuring that the second lithium source can efficiently enter the lithium sites in the lattice, reducing the generation of inactive phase byproducts.

[0038] In some specific embodiments, the molar ratio of lithium content in the second lithium source to the total amount of nickel, cobalt, and manganese in the lithium oxide precursor is (0.35~0.45):1, for example, it can be 0.35:1, 0.37:1, 0.39:1, 0.4:1, 0.41:1, 0.43:1 or 0.45:1.

[0039] In some specific embodiments, the total concentration of nickel, cobalt, and manganese in the lithium-containing metal salt solution is 200 g / L to 300 g / L, for example, it can be 200 g / L, 220 g / L, 240 g / L, 260 g / L, 280 g / L, or 300 g / L.

[0040] In this invention, the spray pyrolysis temperature affects the number and uniformity of ordered superlattice structures in the lithium oxide precursor. If the spray pyrolysis temperature is too low, the ordered superlattice structure cannot be effectively constructed, resulting in a small number of ordered superlattice structures and poor uniformity. If the spray pyrolysis temperature is too high, the number of ordered superlattice structures will be too large, which will increase the resistance to the diffusion of the second lithium source into the lithium sites inside the lattice during the subsequent sintering process, affecting the integrity and stability of the lattice structure of the prepared single-crystal high-nickel ternary cathode material, and leading to an increase in residual lithium on the surface.

[0041] In some specific embodiments, the temperature of the spray pyrolysis is 700℃~900℃, for example, it can be 700℃, 750℃, 800℃, 850℃ or 900℃.

[0042] In this invention, the sintering temperature affects the diffusion rate of the second lithium source into the lithium oxide precursor lattice. Since the lithium oxide precursor prepared in this invention possesses an ordered superlattice structure, if the sintering temperature is too low, the diffusion driving force of lithium ions will be insufficient, making it difficult for lithium ions to diffuse sufficiently into the lithium sites within the lattice. This affects the lithium content in the single-crystal high-nickel cathode material, as well as the integrity and stability of the lattice structure. If the sintering temperature is too high, it may induce the release of lattice oxygen, exacerbating the mixing of cations and anions during sintering, leading to performance degradation of the single-crystal high-nickel cathode material.

[0043] In some specific embodiments, the sintering temperature is 800℃~900℃, for example, it can be 800℃, 820℃, 840℃, 860℃, 880℃ or 900℃.

[0044] In some specific embodiments, the sintering time is 8h to 15h, for example, it can be 8h, 9h, 10h, 11h, 12h, 13h, 14h or 15h.

[0045] In some specific embodiments, the molar ratio of nickel, cobalt, and manganese in the lithium-containing metal salt solution is (0.8~0.95):(0~0.2):(0~0.2), for example, it can be 0.8:0:0.2, 0.8:0.2:0, 0.8:0.1:0.1, 0.82:0.15:0.03, 0.84:0.02:0.14, 0.86:0.05:0.09, 0.88:0.04:0.08, 0.9:0.02:0.08, 0.9:0.04:0.06, 0.91:0.03:0.06, 0.93:0.02:0.05, 0.95:0.01:0.04, or 0.95:0.02:0.03.

[0046] In some specific embodiments, the first lithium salt includes a soluble lithium salt, which includes any one or a combination of at least two of lithium nitrate, lithium chloride, or lithium acetate. Typical but non-limiting combinations include a combination of lithium nitrate and lithium chloride, a combination of lithium acetate and lithium nitrate, or a combination of lithium chloride and lithium acetate.

[0047] In some specific embodiments, the second lithium salt includes any one or a combination of at least two of lithium nitrate, lithium chloride, lithium acetate, lithium oxide, or lithium hydroxide. Typical but non-limiting combinations include combinations of lithium nitrate and lithium chloride, combinations of lithium acetate and lithium oxide, combinations of lithium hydroxide and lithium nitrate, combinations of lithium chloride and lithium acetate, or combinations of lithium oxide and lithium hydroxide.

[0048] In this invention, nickel salt, cobalt salt, and manganese salt each independently include soluble salts of nickel, cobalt, and manganese. Exemplarily, nickel salt includes any one or a combination of at least two of nickel chloride, nickel sulfate, nickel nitrate, or nickel acetate; manganese salt includes any one or a combination of at least two of manganese chloride, manganese sulfate, manganese nitrate, or manganese acetate; and cobalt salt includes any one or a combination of at least two of cobalt chloride, cobalt sulfate, cobalt nitrate, or cobalt acetate.

[0049] In another specific embodiment, the present invention provides a single-crystal high-nickel ternary cathode material, which is obtained by the preparation method described in one of the aforementioned specific embodiments.

[0050] In yet another embodiment, the present invention provides a positive electrode sheet comprising a single-crystal high-nickel ternary positive electrode material as described in another preceding embodiment.

[0051] In another specific embodiment, the present invention provides a lithium-ion battery comprising a single-crystal high-nickel ternary cathode material as described in another specific embodiment above, or comprising a cathode sheet as described in yet another specific embodiment above.

[0052] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0053] Example 1

[0054] This embodiment provides a method for preparing a single-crystal high-nickel ternary cathode material, the method comprising:

[0055] (1) According to the molar ratio of nickel, cobalt and manganese being 0.8:0.05:0.15, and the molar ratio of lithium to the total amount of nickel, cobalt and manganese being 0.7:1, lithium nitrate, nickel nitrate, manganese nitrate and cobalt nitrate were mixed in deionized water to obtain a lithium metal salt solution with a total nickel, cobalt and manganese concentration of 260 g / L.

[0056] (2) Set the temperature of the spray pyrolysis furnace to 700℃, and spray pyrolyze the lithium metal salt solution obtained in step (1) to obtain the lithium oxide precursor.

[0057] (3) The lithium oxide precursor obtained in step (2) is mixed with lithium carbonate according to the molar ratio of lithium in lithium carbonate to the total amount of nickel, cobalt and manganese in lithium oxide precursor is 0.4:1. The mixture is heated to 900°C and sintered for 10 hours in an oxygen atmosphere to obtain the single crystal high nickel ternary cathode material.

[0058] Example 2

[0059] This embodiment provides a method for preparing a single-crystal high-nickel ternary cathode material, the method comprising:

[0060] (1) According to the molar ratio of nickel, cobalt and manganese being 0.9:0.02:0.08, and the molar ratio of lithium to the total amount of nickel, cobalt and manganese being 0.65:1, lithium chloride, nickel chloride, manganese chloride and cobalt chloride were mixed in deionized water to obtain a lithium metal salt solution with a total nickel, cobalt and manganese concentration of 200 g / L.

[0061] (2) Set the temperature of the spray pyrolysis furnace to 800℃, and spray pyrolyze the lithium metal salt solution obtained in step (1) to obtain a lithium oxide precursor.

[0062] (3) The lithium oxide precursor obtained in step (2) and lithium nitrate are mixed according to the molar ratio of lithium in lithium nitrate to the total amount of nickel, cobalt and manganese in lithium oxide precursor is 0.45:1. The mixture is heated to 850°C and sintered for 8 hours in an oxygen atmosphere to obtain the single crystal high nickel ternary cathode material.

[0063] Example 3

[0064] This embodiment provides a method for preparing a single-crystal high-nickel ternary cathode material, the method comprising:

[0065] (1) According to the molar ratio of nickel, cobalt and manganese being 0.95:0.02:0.03, and the molar ratio of lithium to the total amount of nickel, cobalt and manganese being 0.75:1, lithium nitrate, nickel nitrate, manganese nitrate and cobalt nitrate were mixed in deionized water to obtain a lithium metal salt solution with a total nickel, cobalt and manganese concentration of 300 g / L.

[0066] (2) Set the temperature of the spray pyrolysis furnace to 900℃, and spray pyrolyze the lithium metal salt solution obtained in step (1) to obtain the lithium oxide precursor.

[0067] (3) The lithium oxide precursor and lithium oxide obtained in step (2) are mixed according to the molar ratio of lithium in lithium oxide to the total amount of nickel, cobalt and manganese in lithium oxide precursor is 0.35:1. The mixture is heated to 800°C and sintered for 15 hours in an oxygen atmosphere to obtain the single crystal high nickel ternary cathode material.

[0068] Example 4

[0069] This embodiment provides a method for preparing a single-crystal high-nickel ternary cathode material. Except for step (2), in which the temperature of the spray pyrolysis furnace is set to 600°C, the preparation method is the same as in embodiment 1.

[0070] Example 5

[0071] This embodiment provides a method for preparing a single-crystal high-nickel ternary cathode material. Except for step (2), in which the temperature of the spray pyrolysis furnace is set to 950°C, the preparation method is the same as in embodiment 1.

[0072] Example 6

[0073] This embodiment provides a method for preparing a single-crystal high-nickel ternary cathode material. Except for step (3), in which the sintering temperature is 600℃, the preparation method is the same as in Example 1.

[0074] Example 7

[0075] This embodiment provides a method for preparing a single-crystal high-nickel ternary cathode material. Except for step (3), in which the sintering temperature is 1000℃, the preparation method is the same as in Example 1.

[0076] Comparative Example 1

[0077] This comparative example provides a method for preparing a single-crystal high-nickel ternary cathode material. Except for step (1), in which lithium nitrate, nickel nitrate, manganese nitrate and cobalt nitrate are mixed in deionized water without adding lithium nitrate, and in step (3), in which the lithium oxide precursor and lithium carbonate are mixed according to a molar ratio of lithium in lithium carbonate to the total amount of nickel, cobalt and manganese in the lithium oxide precursor is 1.1:1, the rest of the preparation method is the same as in Example 1.

[0078] Comparative Example 2

[0079] This comparative example provides a method for preparing a single-crystal high-nickel ternary cathode material. Except for step (1), in which the molar ratio of lithium content to total nickel, cobalt and manganese in the lithium-containing metal salt solution is 0.6:1, the preparation method is the same as in Example 1.

[0080] Comparative Example 3

[0081] This comparative example provides a method for preparing a single-crystal high-nickel ternary cathode material. Except for step (1), in which the molar ratio of lithium content to total nickel, cobalt and manganese in the lithium-containing metal salt solution is 0.8:1, the preparation method is the same as in Example 1.

[0082] Performance testing:

[0083] The single-crystal high-nickel ternary cathode materials prepared in all the above examples and comparative examples were dispersed in NMP with conductive carbon black and polyvinylidene fluoride at a mass ratio of 97:1.5:1.5 to obtain a cathode slurry, which was then coated on the surface of aluminum foil and dried to obtain a cathode sheet. The cathode sheet was then matched with lithium metal to assemble a lithium-ion battery, and the electrical performance of the lithium-ion battery was tested.

[0084] (1) At 25℃ and within a voltage range of 2.7V to 4.3V, first perform one charge-discharge cycle at a rate of 0.1C to test the first coulombic efficiency (first efficiency) and the 0.1C discharge specific capacity.

[0085] (2) At 25℃ and within the voltage range of 2.7V to 4.3V, charge and discharge at rates of 0.33C / 0.5C / 1C / 3C respectively, and test the nC rate capacity retention rate. nC rate capacity retention rate = nC discharge specific capacity / 0.1C discharge specific capacity.

[0086] (3) At 25℃ and within a voltage range of 2.7V to 4.3V, perform 100 charge-discharge cycles at a 1C rate to test the cycle capacity retention rate. The cycle capacity retention rate = 100 th Discharge specific capacity / 1 st Discharge specific capacity × 100%.

[0087] The test results are shown in Table 1.

[0088] Table 1

[0089]

[0090] Based on the test results of Examples 1 to 7 in Table 1, this invention mixes lithium sources and nickel-cobalt-manganese sources in a solution and uses a spray pyrolysis process to complete the oxidative decomposition of the solution in a very short time, obtaining a lithium-containing oxide precursor with atomically uniform distribution of lithium and nickel-cobalt-manganese. This increases the number and uniformity of ordered superlattice structures in the lithium-containing oxide precursor, thereby reducing the mixing of anions and cations during sintering, reducing the release of lattice oxygen, and improving the structural stability of the single-crystal high-nickel ternary cathode material.

[0091] Based on the test results of Examples 1, 4, and 5, the spray pyrolysis temperature affects the quantity and uniformity of ordered superlattice structures in the lithium oxide precursor. Both excessively high and low spray pyrolysis temperatures can lead to a decrease in the electrochemical performance of single-crystal high-nickel ternary cathode materials.

[0092] According to the test results of Examples 1, 6 and 7, the sintering temperature affects the diffusion rate of the second lithium source into the lithium oxide precursor lattice, which in turn affects the integrity and stability of the lattice structure of the single-crystal high-nickel ternary cathode material. Too high or too low a sintering temperature is not conducive to improving the performance of the single-crystal high-nickel ternary cathode material.

[0093] Based on the test results of Example 1, Comparative Examples 1 and 2, if all the lithium source is added to the lithium metal salt solution, the problem of lithium-nickel mixing caused by high nickel content during sintering cannot be effectively avoided, which is not conducive to improving the performance of single-crystal high-nickel ternary cathode material. If all the lithium source is added during the sintering process, an ordered superlattice structure cannot be constructed inside the oxide precursor, and lattice oxygen cannot be effectively bound, resulting in the temperature of lattice oxygen release not being resolved, which is not conducive to improving the performance of single-crystal high-nickel ternary cathode material.

[0094] According to the test results of Example 1, Comparative Examples 3 and 4, if the molar ratio of lithium content to total nickel, cobalt and manganese in the lithium-containing metal solution is too high or too low, the number and uniformity of ordered superlattice structures in the lithium oxide precursor cannot be effectively controlled within a suitable range. This makes it impossible to effectively bind lattice oxygen while reducing the generation of inactive phases, resulting in a deterioration in the performance of single-crystal high-nickel ternary cathode materials.

[0095] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a single-crystal high-nickel ternary cathode material, characterized in that, The preparation method includes: A lithium-containing metal salt solution is obtained by mixing a first lithium source, nickel salt, manganese salt, and cobalt salt; the lithium-containing metal salt solution is then subjected to spray pyrolysis to obtain a lithium oxide precursor. The lithium oxide precursor is mixed with a second lithium source and sintered to obtain the single-crystal high-nickel ternary cathode material. In the lithium-containing metal salt solution, the molar ratio of lithium content to total nickel, cobalt, and manganese is (0.65~0.75):

1.

2. The preparation method according to claim 1, characterized in that, The molar ratio of lithium content in the second lithium source to the total amount of nickel, cobalt, and manganese in the lithium oxide precursor is (0.35~0.45):

1.

3. The preparation method according to claim 1 or 2, characterized in that, The total concentration of nickel, cobalt, and manganese in the lithium-containing metal salt solution is 200 g / L to 300 g / L.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The spray pyrolysis temperature is 700℃~900℃.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The sintering temperature is 800℃~900℃; And / or, the sintering time is 8h~15h.

6. The preparation method according to any one of claims 1 to 5, characterized in that, In the lithium-containing metal salt solution, the molar ratio of nickel, cobalt, and manganese is (0.8~0.95):(0~0.2):(0~0.2).

7. The preparation method according to any one of claims 1 to 6, characterized in that, The first lithium salt includes a soluble lithium salt, which includes any one or a combination of at least two of lithium nitrate, lithium chloride, or lithium acetate; And / or, the second lithium salt comprises any one or a combination of at least two of lithium nitrate, lithium chloride, lithium acetate, lithium oxide, or lithium hydroxide.

8. A single-crystal high-nickel ternary cathode material, characterized in that, The single-crystal high-nickel ternary cathode material is obtained by the preparation method described in any one of claims 1 to 7.

9. A positive electrode plate, characterized in that, The cathode material comprises the single-crystal high-nickel ternary cathode material as described in claim 8.

10. A lithium-ion battery, characterized in that, The lithium-ion battery includes the single-crystal high-nickel ternary cathode material as described in claim 8, or includes the cathode sheet as described in claim 9.

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