A TiSiO4 coating for ternary cathode material, preparation method and battery

Abstract

This invention provides a TiSiO4-coated ternary cathode material, its preparation method, and a battery. The preparation method includes: mixing the ternary cathode material with a TiSiO4 suspension to obtain a mixed suspension; vacuum drying the mixed suspension to remove the solvent to obtain a modified precursor; and heat-treating the modified precursor in an oxygen-containing atmosphere to obtain the TiSiO4-coated ternary cathode material. The TiSiO4-coated ternary cathode material preparation method provided by this invention enables uniform deposition of the TiSiO4 coating on the surface of the ternary cathode material, improving the adhesion between the coating and the ternary cathode material, thereby enhancing the cycle stability, rate performance, and capacity retention of the cathode material, providing material support for the development of high-energy-density lithium-ion batteries.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to a modified ternary cathode material, particularly to a TiSiO4 coated ternary cathode material, its preparation method, and a battery. Background Technology

[0002] Lithium-ion batteries (LIBs) have become the primary energy source for electric vehicles (EVs) due to their high volumetric energy density and high mass energy density. The cathode material is a key component determining the battery's energy density. Nickel-rich ternary transition metal oxides (Ni>0.6%) are considered ideal cathode materials for next-generation commercial lithium-ion batteries due to their high operating potential, excellent practical capacity, and relatively low cost.

[0003] However, high-nickel ternary cathode materials face many challenges in commercialization, including the need to add lithium during the preparation process due to the high nickel content, in order to prevent Ni from precipitating. 2+ / Li + Cation mixing occurs, and residual lithium readily reacts with moisture in the air to form Li₂CO₃; oxidation of lattice oxygen leads to oxygen loss, forming an irreversible rock salt phase, which reduces the lithium diffusion coefficient; interfacial side reactions between the cathode and electrolyte form a CEI layer, restricting lithium diffusion and increasing charge transfer resistance; during delithiation, Ni… 4+ Easily reduced to Ni 2+ It releases oxygen, triggering thermal runaway and capacity decay; during cycling, the unit cell shrinks and forms microcracks, leading to cathode degradation.

[0004] To address the aforementioned issues, existing technologies employ modification methods such as surface coating, doping, and concentration gradient structures. Among these, surface coating technology is widely used due to its ease of operation. Commonly used coating materials are TiO2 or SiO2. TiO2 inhibits surface reactions due to its chemical inertness and high voltage stability, while SiO2 reduces electrode corrosion by adsorbing HF. However, existing technologies also have significant drawbacks: single coatings have limited functionality and cannot simultaneously address multiple problems; improvements in cycle stability are limited, with capacity retention generally below 20% after 250 cycles at high voltage; interfacial compatibility is poor, leading to easy coating detachment and increased charge transfer resistance; and some preparation processes are complex, costly, and difficult to scale up for mass production.

[0005] Therefore, developing a TiSiO4 coating for ternary cathode materials that combines structural stability, chemical barrier function, and ion conduction capability is of great significance for promoting the development of high-energy-density lithium-ion batteries. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a TiSiO4 coating for ternary cathode materials, a preparation method, and a battery. The preparation method solves problems such as oxygen release, cation mixing, interfacial side reactions, and mechanical damage under high voltage conditions in cathode materials. It enables uniform deposition of the TiSiO4 coating on the surface of the ternary cathode material, improves the adhesion between the coating and the ternary cathode material, thereby enhancing the cycle stability, rate performance, and capacity retention of the cathode material, and providing material support for the development of high-energy-density lithium-ion batteries.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a TiSiO4 coating-coated ternary cathode material, the method comprising the following steps:

[0009] A ternary cathode material is mixed with a TiSiO4 suspension to obtain a mixed suspension; the mixed suspension is vacuum dried to remove the solvent to obtain a coated and modified precursor; the coated and modified precursor is heat-treated in an oxygen-containing atmosphere to obtain the TiSiO4-coated ternary cathode material.

[0010] TiSiO4 coatings can combine the structural stability of TiO2 with the chemical barrier effect of SiO2. 4+ It can suppress oxygen release and lattice distortion, Si 4+ It can adsorb HF and reduce transition metal dissolution, while the zircon-like structure of TiSiO4 can promote Li + Diffusion addresses the functional defects of single coatings; the TiSiO4 coating can induce the formation of a thin and stable CEI layer, reducing electrolyte decomposition and LiF generation, lowering charge transfer resistance, and suppressing the irreversible phase transition of the H2-H3 phase, thus improving the structural integrity of the cathode material; moreover, the preparation method adopts a wet chemical route of solution dispersion-adsorption coating-vacuum drying-heat treatment, ensuring the uniformity of the TiSiO4 coating and the strong bonding between the coating and the ternary cathode material, avoiding the damage to the crystal structure of the cathode material caused by high-temperature calcination.

[0011] In some embodiments, the mass of TiSiO4 in the TiSiO4 suspension is 0.5wt% to 1.5wt% of the ternary cathode material.

[0012] In some embodiments, the ternary cathode material is LiNi. x Mn y Co z O2, where x+y+z=1, x≥0.8, 0.01≤y≤0.1.

[0013] In some embodiments, the average particle size of the secondary particles in the ternary cathode material is 15 μm to 16 μm.

[0014] In some embodiments, the average particle size of TiSiO4 in the TiSiO4 suspension is ≤50nm.

[0015] In some embodiments, the solvent for the TiSiO4 suspension is an alcohol-based organic solvent.

[0016] In some embodiments, the mixing is carried out at room temperature.

[0017] In some embodiments, the mixing method includes magnetic stirring.

[0018] In some embodiments, the vacuum drying temperature is 40°C to 60°C.

[0019] In some embodiments, the vacuum drying time is 12h to 18h.

[0020] In some embodiments, the heating rate of the heat treatment is 5°C / min to 10°C / min.

[0021] In some embodiments, the heat treatment holding temperature is 450°C to 550°C.

[0022] In some embodiments, the heat treatment holding time is 3h to 6h.

[0023] In some embodiments, the gas used in the oxygen-containing atmosphere includes air.

[0024] In a second aspect, the present invention provides a TiSiO4-coated ternary cathode material, wherein the TiSiO4-coated ternary cathode material is prepared by the preparation method described in the first aspect.

[0025] Thirdly, the present invention provides a battery comprising a TiSiO4-coated ternary cathode material prepared by the preparation method described in the first aspect, or comprising a TiSiO4-coated ternary cathode material as described in the second aspect.

[0026] 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.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The TiSiO4 coating provided by this invention coats ternary cathode materials. The TiSiO4 coating combines the structural stability of TiO2 with the chemical barrier effect of SiO2. 4+ It can suppress oxygen release and lattice distortion, Si 4+ It can adsorb HF and reduce transition metal dissolution, while the zircon-like structure of TiSiO4 can promote Li + Diffusion addresses the functional defects of single coatings; the TiSiO4 coating can induce the formation of a thin and stable CEI layer, reducing electrolyte decomposition and LiF generation, lowering charge transfer resistance, and simultaneously suppressing the irreversible phase transition of the H2-H3 phase, thus improving the structural integrity of the cathode material; moreover, the preparation method of the TiSiO4 coating-coated ternary cathode material provided by this invention adopts a wet chemical route of solution dispersion-adsorption coating-vacuum drying-heat treatment, ensuring the uniformity of the TiSiO4 coating and the firm bonding between the coating and the ternary cathode material, and avoiding the damage to the crystal structure of the cathode material caused by high-temperature calcination. Detailed Implementation

[0029] 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.

[0030] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0031] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0032] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0033] 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 places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0034] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0035] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0036] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These 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" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0037] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0038] In this invention, "optional" means that something is optional, that is, it refers to either "with" or "without". If there are multiple "optional" options in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "optional" option is independent.

[0039] In existing technologies, while TiO2 coatings can improve structural stability, they have poor ionic conductivity, and thick coatings can hinder Li... + Diffusion; Although SiO2 coatings can adsorb HF, their mechanical strength is insufficient, and they are prone to detachment after long-term cycling, failing to simultaneously address issues such as oxygen release, cation mixing, and interfacial side reactions in nickel-rich ternary materials; Furthermore, existing coating materials struggle to suppress the irreversible H2-H3 phase transition in nickel-rich ternary materials under high voltage (≥4.5V), resulting in rapid capacity decay during cycling, with capacity retention generally below 20% after 250 cycles; The adhesion between single-component coatings and the surface of nickel-rich ternary materials is weak, easily forming a thick and uneven CEI (cathode electrolyte interphase) layer, increasing charge transfer resistance and reducing the rate performance of the material; Existing coating preparation methods such as sputtering and evaporation require specialized equipment, resulting in high costs and difficulties in large-scale production, while wet preparation methods produce coatings with poor uniformity, easily leading to material agglomeration.

[0040] An embodiment of the present invention provides a method for preparing a TiSiO4 coating on a ternary cathode material, the method comprising the following steps:

[0041] A ternary cathode material is mixed with a TiSiO4 suspension to obtain a mixed suspension; the mixed suspension is vacuum dried to remove the solvent to obtain a coated and modified precursor; the coated and modified precursor is heat-treated in an oxygen-containing atmosphere to obtain the TiSiO4-coated ternary cathode material.

[0042] TiSiO4 coatings can combine the structural stability of TiO2 with the chemical barrier effect of SiO2. 4+ It can suppress oxygen release and lattice distortion, Si 4+ It can adsorb HF and reduce transition metal dissolution, while the zircon-like structure of TiSiO4 can promote Li + Diffusion addresses the functional defects of single coatings; the TiSiO4 coating can induce the formation of a thin and stable CEI layer, reducing electrolyte decomposition and LiF generation, lowering charge transfer resistance, and suppressing the irreversible phase transition of the H2-H3 phase, thus improving the structural integrity of the cathode material; moreover, the preparation method adopts a wet chemical route of solution dispersion-adsorption coating-vacuum drying-heat treatment, ensuring the uniformity of the TiSiO4 coating and the strong bonding between the coating and the ternary cathode material, avoiding the damage to the crystal structure of the cathode material caused by high-temperature calcination.

[0043] In some embodiments, the mass of TiSiO4 in the TiSiO4 suspension is 0.5wt% to 1.5wt% of the ternary cathode material, for example, it can be 0.5wt%, 0.6wt%, 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt% or 1.5wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0044] The present invention controls the mass of TiSiO4 in the TiSiO4 suspension to be 0.5wt%~1.5wt% of the ternary cathode material, which can obtain a TiSiO4 coating with uniform thickness and a thickness of 10nm~13nm, thus achieving the best balance between surface protection and ion transport.

[0045] In some embodiments, the ternary cathode material is LiNi. x Mn y Co z O2, where x + y + z = 1, x ≥ 0.8, 0.01 ≤ y ≤ 0.1. Optionally, the ternary cathode material can be LiNi. 0.83 Mn 0.06 Co 0.11 O2 (NCM-83).

[0046] In some embodiments, the average particle size of the secondary particles of the ternary cathode material is 15μm to 16μm, for example, it can be 15μm, 15.1μm, 15.2μm, 15.3μm, 15.4μm, 15.5μm, 15.6μm, 15.7μm, 15.8μm, 15.9μm or 16μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0047] In some embodiments, the average particle size of TiSiO4 in the TiSiO4 suspension is ≤50nm, for example, it can be 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm or 50nm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0048] In some embodiments, the solvent for the TiSiO4 suspension is an alcohol-based organic solvent.

[0049] For example, the alcoholic organic solvent includes anhydrous ethanol.

[0050] In some embodiments, the mixing is carried out at room temperature.

[0051] In this invention, "room temperature" generally refers to 4℃~35℃, and can refer to 20℃±5℃. In some embodiments of this invention, room temperature refers to 20℃~30℃.

[0052] In some embodiments, the mixing method includes magnetic stirring.

[0053] This invention does not impose specific limitations on the conditions for magnetic stirring, as long as a uniformly dispersed mixed suspension can be obtained.

[0054] In some embodiments, the vacuum drying temperature is 40°C to 60°C, for example, it can be 45°C, 45°C, 50°C, 55°C or 60°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0055] In some embodiments, the vacuum drying time is 12h to 18h, for example, it can be 12h, 13h, 14h, 15h, 16h, 17h or 18h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0056] In some embodiments, the heating rate of the heat treatment is 5°C / min to 10°C / min, for example, it can be 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0057] A suitable heat treatment temperature can prevent the destruction of the crystal structure of the substrate material (ternary cathode material) while ensuring a strong bond between the TiSiO4 coating and the substrate material.

[0058] In some embodiments, the heat treatment holding temperature is 450℃~550℃, for example, it can be 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃, 540℃ or 550℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0059] In some embodiments, the heat treatment holding time is 3h to 6h, for example, it can be 3h, 4h, 5h or 6h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0060] In some embodiments, the gas used in the oxygen-containing atmosphere includes air.

[0061] As a preferred embodiment of the preparation method provided by the present invention, the preparation method includes the following steps:

[0062] (1) The ternary cathode material and TiSiO4 suspension were mixed by magnetic stirring at room temperature to obtain a mixed suspension;

[0063] The ternary cathode material is LiNi. 0.83 Mn 0.06 Co 0.11 O2 has a secondary particle size of 15μm~16μm;

[0064] In the TiSiO4 suspension, the average particle size of TiSiO4 is ≤50nm, and its solvent is anhydrous ethanol;

[0065] The mass of TiSiO4 in the TiSiO4 suspension is 0.5wt%~1.5wt% of the ternary cathode material;

[0066] (2) The mixed suspension is vacuum dried to remove the solvent, thereby obtaining the coated modified precursor;

[0067] The vacuum drying temperature is 40℃~60℃, and the time is 12h~18h;

[0068] (3) Heat-treat the modified precursor in air atmosphere to obtain the TiSiO4 coated ternary cathode material;

[0069] The heating rate of the heat treatment is 5℃ / min to 10℃ / min, the holding temperature is 450℃ to 550℃, and the holding time is 3h to 6h.

[0070] An embodiment of the present invention provides a TiSiO4-coated ternary cathode material, wherein the TiSiO4-coated ternary cathode material is prepared by the preparation method described in any embodiment.

[0071] The TiSiO4 coating of the ternary cathode material provided by the present invention has a uniform layered α-NaFeO2 structure (R-3m space group), low cation mixing degree, I(003) / I(104) ratio ≥1.4994, and still maintains stable polycrystalline characteristics after cycling.

[0072] The battery corresponding to the TiSiO4 coating of the ternary cathode material provided by the present invention has a capacity retention rate of ≥20% after 250 cycles at 4.5V and 0.5C rate; and a capacity retention rate of ≥15% after 300 cycles at 2C rate, with a charge transfer resistance of ≤45Ω.

[0073] An embodiment of the present invention provides a battery comprising a TiSiO4-coated ternary cathode material prepared by the preparation method described in any embodiment, or comprising a TiSiO4-coated ternary cathode material as described in any embodiment.

[0074] Example 1

[0075] This embodiment provides a method for preparing a TiSiO4 coating on a ternary cathode material, including:

[0076] (1) The ternary cathode material and TiSiO4 suspension were mixed by magnetic stirring at room temperature to obtain a mixed suspension;

[0077] The ternary cathode material is LiNi. 0.83 Mn 0.06 Co 0.11 O2, whose secondary particles have an average particle size of 15.5 μm;

[0078] The TiSiO4 suspension has an average particle size of 50 nm and its solvent is anhydrous ethanol.

[0079] The mass of TiSiO4 in the TiSiO4 suspension is 1 wt% of the ternary cathode material.

[0080] (2) The mixed suspension is vacuum dried to remove the solvent, thereby obtaining the coated modified precursor;

[0081] The vacuum drying temperature is 50℃ and the time is 15 hours;

[0082] (3) Heat-treat the modified precursor in air atmosphere to obtain the TiSiO4 coated ternary cathode material;

[0083] The heat treatment has a heating rate of 5℃ / min, a holding temperature of 500℃, and a holding time of 5h.

[0084] Example 2

[0085] This embodiment provides a method for preparing a TiSiO4-coated ternary cathode material. Except that the mass of TiSiO4 in the TiSiO4 suspension is 0.5 wt% of the ternary cathode material, all other methods are the same as in Example 1, including:

[0086] (1) The ternary cathode material and TiSiO4 suspension were mixed by magnetic stirring at room temperature to obtain a mixed suspension;

[0087] The ternary cathode material is LiNi. 0.83 Mn 0.06 Co 0.11 O2, whose secondary particles have an average particle size of 15.5 μm;

[0088] The TiSiO4 suspension has an average particle size of 50 nm and its solvent is anhydrous ethanol.

[0089] The mass of TiSiO4 in the TiSiO4 suspension is 0.5 wt% of the ternary cathode material.

[0090] (2) The mixed suspension is vacuum dried to remove the solvent, thereby obtaining the coated modified precursor;

[0091] The vacuum drying temperature is 50℃ and the time is 15 hours;

[0092] (3) Heat-treat the modified precursor in air atmosphere to obtain the TiSiO4 coated ternary cathode material;

[0093] The heat treatment has a heating rate of 5℃ / min, a holding temperature of 500℃, and a holding time of 5h.

[0094] Example 3

[0095] This embodiment provides a method for preparing a TiSiO4-coated ternary cathode material. Except that the mass of TiSiO4 in the TiSiO4 suspension is 1.5 wt% of the ternary cathode material, all other methods are the same as in Example 1, including:

[0096] (1) The ternary cathode material and TiSiO4 suspension were mixed by magnetic stirring at room temperature to obtain a mixed suspension;

[0097] The ternary cathode material is LiNi. 0.83 Mn 0.06 Co0.11 O2, whose secondary particles have an average particle size of 15.5 μm;

[0098] The TiSiO4 suspension has an average particle size of 50 nm and its solvent is anhydrous ethanol.

[0099] The mass of TiSiO4 in the TiSiO4 suspension is 1.5 wt% of the ternary cathode material.

[0100] (2) The mixed suspension is vacuum dried to remove the solvent, thereby obtaining the coated modified precursor;

[0101] The vacuum drying temperature is 50℃ and the time is 15 hours;

[0102] (3) Heat-treat the modified precursor in air atmosphere to obtain the TiSiO4 coated ternary cathode material;

[0103] The heat treatment has a heating rate of 5℃ / min, a holding temperature of 500℃, and a holding time of 5h.

[0104] Example 4

[0105] This embodiment provides a method for preparing a TiSiO4 coating on a ternary cathode material, including:

[0106] (1) The ternary cathode material and TiSiO4 suspension were mixed by magnetic stirring at room temperature to obtain a mixed suspension;

[0107] The ternary cathode material is LiNi. 0.83 Mn 0.06 Co 0.11 O2, whose secondary particles have an average particle size of 15μm;

[0108] The TiSiO4 suspension has an average particle size of 50 nm and its solvent is anhydrous ethanol.

[0109] The mass of TiSiO4 in the TiSiO4 suspension is 1 wt% of the ternary cathode material.

[0110] (2) The mixed suspension is vacuum dried to remove the solvent, thereby obtaining the coated modified precursor;

[0111] The vacuum drying temperature is 40℃ and the time is 18h;

[0112] (3) Heat-treat the modified precursor in air atmosphere to obtain the TiSiO4 coated ternary cathode material;

[0113] The heat treatment has a heating rate of 5℃ / min, a holding temperature of 450℃, and a holding time of 6h.

[0114] Example 5

[0115] This embodiment provides a method for preparing a TiSiO4 coating on a ternary cathode material, including:

[0116] (1) The ternary cathode material and TiSiO4 suspension were mixed by magnetic stirring at room temperature to obtain a mixed suspension;

[0117] The ternary cathode material is LiNi. 0.83 Mn 0.06 Co 0.11 O2, whose secondary particles have an average particle size of 16μm;

[0118] The TiSiO4 suspension has an average particle size of 50 nm and its solvent is anhydrous ethanol.

[0119] The mass of TiSiO4 in the TiSiO4 suspension is 1 wt% of the ternary cathode material.

[0120] (2) The mixed suspension is vacuum dried to remove the solvent, thereby obtaining the coated modified precursor;

[0121] The vacuum drying temperature is 60℃ and the time is 12 hours;

[0122] (3) Heat-treat the modified precursor in air atmosphere to obtain the TiSiO4 coated ternary cathode material;

[0123] The heat treatment has a heating rate of 10℃ / min, a holding temperature of 550℃, and a holding time of 3h.

[0124] Example 6

[0125] This embodiment provides a method for preparing a TiSiO4 coating on a ternary cathode material. Except that the mass of TiSiO4 in the TiSiO4 suspension is 0.1 wt% of the ternary cathode material, everything else is the same as in Example 1.

[0126] Example 7

[0127] This embodiment provides a method for preparing a TiSiO4 coating on a ternary cathode material. Except that the mass of TiSiO4 in the TiSiO4 suspension is 2wt% of the ternary cathode material, the rest is the same as in Example 1.

[0128] Comparative Example 1

[0129] This comparative example provides a ternary cathode material, which is the LiNi cathode material from Example 1. 0.83 Mn 0.06 Co 0.11 O2.

[0130] Comparative Example 2

[0131] This comparative example provides a method for preparing a TiO2-coated ternary cathode material, including:

[0132] (1) The ternary cathode material and TiO2 suspension were magnetically stirred at room temperature to obtain a mixed suspension;

[0133] The ternary cathode material is LiNi. 0.83 Mn 0.06 Co 0.11 O2, whose secondary particles have an average particle size of 15.5 μm;

[0134] The TiO2 suspension has an average particle size of 50 nm and its solvent is anhydrous ethanol.

[0135] The mass of TiO2 in the TiO2 suspension is 1 wt% of the ternary cathode material.

[0136] (2) The mixed suspension is vacuum dried to remove the solvent, thereby obtaining the coated modified precursor;

[0137] The vacuum drying temperature is 50℃ and the time is 15 hours;

[0138] (3) Heat-treat the modified precursor in air atmosphere to obtain the TiO2-coated ternary cathode material;

[0139] The heat treatment has a heating rate of 5℃ / min, a holding temperature of 500℃, and a holding time of 5h.

[0140] Comparative Example 3

[0141] This comparative example provides a method for preparing a SiO2-coated ternary cathode material, including:

[0142] (1) The ternary cathode material and SiO2 suspension were mixed by magnetic stirring at room temperature to obtain a mixed suspension;

[0143] The ternary cathode material is LiNi. 0.83 Mn 0.06 Co 0.11 O2, whose secondary particles have an average particle size of 15.5 μm;

[0144] The SiO2 suspension has an average particle size of 50 nm and its solvent is anhydrous ethanol.

[0145] The mass of SiO2 in the SiO2 suspension is 1 wt% of the ternary cathode material.

[0146] (2) The mixed suspension is vacuum dried to remove the solvent, thereby obtaining the coated modified precursor;

[0147] The vacuum drying temperature is 50℃ and the time is 15 hours;

[0148] (3) Heat-treat the modified precursor in air atmosphere to obtain the SiO2-coated ternary cathode material;

[0149] The heat treatment has a heating rate of 5℃ / min, a holding temperature of 500℃, and a holding time of 5h.

[0150] Performance Characterization

[0151] The positive electrode materials provided in the above embodiments and comparative examples were assembled into coin half-cells for cycle performance testing. The positive electrode sheet was prepared as follows: NCM-83 positive electrode material, conductive adhesive (CB), and binder were mixed at a mass ratio of 92:4:4. The mixture was then mixed with NMP (N-methylpyrrolidone) at a liquid-to-solid ratio of 1:1.3 to form a slurry. The slurry was poured onto aluminum foil and heated in a vacuum oven at 40°C for 6 hours, followed by heating at 110°C for 12 hours to remove NMP. The resulting electrode sheet was then punched into 14mm diameter discs on a punching machine to prepare the coin half-cell. The electrolyte used was a 1M LiPF6 solution dissolved in a 1 / 1 / 1 volume mixture of EC / EMC / EFC. A porous polyethylene membrane was used as the separator. A lithium sheet was used as the negative electrode.

[0152] The battery assembly sequence was as follows: positive electrode case, positive electrode sheet, separator, electrolyte, lithium anode, and anode case. All operations were performed in an argon-protected glove box. Constant current charge-discharge was used to test the battery's cycle performance at room temperature, with a voltage range of 2.8V to 4.5V. The initial discharge specific capacity was measured under 0.1C and 1C conditions. Cycle stability testing involved initial activation cycling at 0.1C, followed by 250 cycles at 0.5C and 300 cycles at 2C. The discharge capacity and capacity retention were recorded after each cycle. The cycle performance results are shown in Table 1.

[0153] Table 1

[0154]

[0155] As can be seen from Examples 1 to 5 in Table 1, the TiSiO4-coated modified ternary cathode material provided by the present invention can basically maintain the initial discharge specific capacity of the unmodified material, while the discharge specific capacity at 1C rate is slightly improved, and it exhibits significantly better long-cycle stability than the unmodified and single-component coated materials at 0.5C and 2C high rates.

[0156] A comparison of Comparative Examples 2 and 3 with Example 1 shows that only Ti 4+ With Si 4+ A synergistic TiSiO4 composite coating is necessary to simultaneously achieve excellent structural stability, chemical barrier properties, and ion conduction. When only TiO2 is used for coating, it lacks Si... 4+ The specific adsorption of HF cannot effectively prevent the corrosion of the positive electrode surface by HF in the electrolyte, and the problem of transition metal dissolution remains prominent. During long-term cycling, the interfacial impedance increases rapidly. The capacity retention rate after 250 cycles at 0.5C is only 19.8%, and after 300 cycles at 2C, it is only 12.4%, which is lower than that of Example 1 with TiSiO4 coating. When only SiO2 is used for coating, its structural support is insufficient, making it difficult to effectively suppress oxygen release and the irreversible phase transition of H2-H3. Moreover, the poor intrinsic lithium-ion conductivity of SiO2 will significantly hinder the Li-ion exchange. + The interface transfer caused the battery's rate performance and cycle performance to be inferior to those of the TiSiO4-coated sample. Its capacity retention rate after 250 cycles at 0.5C was only 17.9%, and after 300 cycles at 2C was only 10.2%.

[0157] A comparison of Examples 1, 6, and 7 shows that there is a strict optimal range for the amount of TiSiO4 coating. When the amount of TiSiO4 is too small, a continuous and complete coating layer cannot be formed on the surface of the ternary cathode particles, making it difficult to fully exert its structural protection and chemical barrier functions. The improvement effect on cycle performance is extremely limited, with a capacity retention rate of only 16.2% after 250 cycles at 0.5C and only 9.1% after 300 cycles at 2C. When the amount of TiSiO4 is too large, the excessively thick coating layer will significantly increase the interfacial transport resistance of lithium ions, and at the same time reduce the mass ratio of active material in the positive electrode. This causes the battery's first discharge specific capacity to drop from 220 mAh / g to 208 mAh / g, the 1C rate discharge specific capacity to drop from 193.9 mAh / g to 181.2 mAh / g, and the cycle performance to drop significantly. The capacity retention rate after 250 cycles at 0.5C is only 18.5%, and the capacity retention rate after 300 cycles at 2C is only 10.6%, which is only slightly better than the uncoated sample.

[0158] In summary, the TiSiO4 coating can combine the structural stability of TiO2 with the chemical barrier effect of SiO2.4+ It can suppress oxygen release and lattice distortion, Si 4+ It can adsorb HF and reduce transition metal dissolution, while the zircon-like structure of TiSiO4 can promote Li + Diffusion addresses the functional defects of single coatings; the TiSiO4 coating can induce the formation of a thin and stable CEI layer, reducing electrolyte decomposition and LiF generation, lowering charge transfer resistance, and suppressing the irreversible phase transition of the H2-H3 phase, thus improving the structural integrity of the cathode material; moreover, the preparation method adopts a wet chemical route of solution dispersion-adsorption coating-vacuum drying-heat treatment, ensuring the uniformity of the TiSiO4 coating and the strong bonding between the coating and the ternary cathode material, avoiding the damage to the crystal structure of the cathode material caused by high-temperature calcination.

[0159] 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 TiSiO4 coating on a ternary cathode material, characterized in that, The preparation method includes the following steps: A ternary cathode material and a TiSiO4 suspension are mixed to obtain a mixed suspension; the mixed suspension is vacuum dried to remove the solvent, resulting in a coated and modified precursor. The modified precursor is heat-treated in an oxygen-containing atmosphere to obtain the TiSiO4-coated ternary cathode material.

2. The preparation method according to claim 1, characterized in that, The mass of TiSiO4 in the TiSiO4 suspension is 0.5wt% to 1.5wt% of the ternary cathode material.

3. The preparation method according to claim 1 or 2, characterized in that, The ternary cathode material is LiNi. x Mn y Co z O2, where x+y+z=1, x≥0.8, 0.01≤y≤0.1; And / or, the average particle size of the secondary particles in the ternary cathode material is 15μm~16μm.

4. The preparation method according to any one of claims 1 to 3, characterized in that, In the TiSiO4 suspension, the average particle size of TiSiO4 is ≤50nm; And / or, the solvent for the TiSiO4 suspension is an alcohol-based organic solvent.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The mixing was carried out at room temperature. And / or, the mixing method includes magnetic stirring.

6. The preparation method according to any one of claims 1 to 5, characterized in that, The vacuum drying temperature is 40℃~60℃; And / or, the vacuum drying time is 12h~18h.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The heating rate of the heat treatment is 5℃ / min to 10℃ / min; And / or, the heat treatment holding temperature is 450℃~550℃; And / or, the heat treatment holding time is 3h~6h.

8. The preparation method according to any one of claims 1 to 7, characterized in that, The gas used in the oxygen-containing atmosphere includes air.

9. A TiSiO4 coating-coated ternary cathode material, characterized in that, The TiSiO4 coating on the ternary cathode material is prepared by the preparation method described in any one of claims 1 to 8.

10. A battery, characterized in that, The battery comprises a TiSiO4-coated ternary cathode material prepared by the preparation method according to any one of claims 1 to 8, or comprises a TiSiO4-coated ternary cathode material according to claim 9.

Images