Modified ternary positive electrode material, preparation method therefor, positive electrode sheet, and lithium battery

Abstract

The present disclosure relates to the technical field of lithium batteries, and discloses a modified ternary positive electrode material, a preparation method therefor, a positive electrode sheet, and a lithium battery. The modified ternary positive electrode material provided by the present disclosure has a dual coating layer, wherein an inner layer is coated with Li2ZrO3, an outer layer is coated with AlPO4, and the Li2ZrO3 of the inner layer is a fast lithium-ion conductor, which improves lithium-ion interfacial kinetics and improves rate performance of the ternary positive electrode material; the AlPO4 of the outer layer, by means of strong covalent interaction between PO4 3- and Al3+, allows for effective resistance against electrolyte corrosion, thereby reducing the occurrence of surface side reactions. Moreover, an AlPO4 coating layer with good thermal stability also improves thermal stability of the ternary positive electrode material. Therefore, the modified ternary positive electrode material provided by the present disclosure can simultaneously improve particle surface stability and conductivity, which is beneficial to simultaneously improving ternary material rate performance and cycle stability.

Description

A modified ternary cathode material and its preparation method, cathode sheet and lithium battery

[0001] Cross-reference to related applications

[0002] This disclosure claims priority to Chinese Patent Application No. 202510491355.3, filed on April 18, 2025, entitled "A Modified Ternary Cathode Material and Its Preparation Method, Cathode Sheet and Lithium Battery", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of lithium battery technology, and more specifically, to a modified ternary cathode material and its preparation method, a cathode sheet, and a lithium battery. Background Technology

[0004] Under high voltage and high temperature conditions, the surface structure stability of single-crystal ternary cathode material particles will significantly decrease, leading to battery performance failure. In industrial applications, traditional dry coating technology achieves poor uniformity, making it difficult to fully protect the particle surface and limiting its effect on improving battery performance. Furthermore, while most inert coating layers can improve particle stability to some extent, they often reduce the material's capacity and surface conductivity.

[0005] Therefore, how to simultaneously improve the stability and conductivity of particle surfaces in large-scale production has become a key challenge restricting the development of ternary materials.

[0006] In view of this, this disclosure is hereby made. Summary of the Invention

[0007] The purpose of this disclosure is to provide a modified ternary cathode material and its preparation method, cathode sheet and lithium battery, which aims to simultaneously improve the stability and conductivity of the particle surface.

[0008] This disclosure is implemented as follows:

[0009] In a first aspect, this disclosure provides a modified ternary cathode material, comprising a ternary cathode material matrix, wherein an inner coating layer and an outer coating layer are sequentially coated on the ternary cathode material matrix, the inner coating layer containing Li2ZrO3 and the outer coating layer containing AlPO4.

[0010] In an optional embodiment, the total amount of the inner coating layer and the outer coating layer is in a mass ratio of (1-5):100 to the ternary cathode material matrix, preferably (2.5-3.5):100;

[0011] And / or, the molar ratio of Li2ZrO3 to AlPO4 is (1-3):1;

[0012] And / or, the chemical formula of the ternary cathode material matrix is ​​LiNi x Co y Mn z O2, 0.6<x<0.7, 0.1<y<0.2, 0.2<z<0.3.

[0013] Secondly, this disclosure provides a method for preparing any of the modified ternary cathode materials in the foregoing embodiments, comprising: forming an inner coating layer and an outer coating layer on a ternary cathode material substrate.

[0014] In an optional embodiment, the method includes: configuring a first raw material liquid for forming an inner coating layer and a second raw material liquid for forming an outer coating layer; placing a ternary cathode material matrix in a spray fluidized bed cavity; sequentially spraying the atomized first and second raw material liquids; and then calcining the substrate.

[0015] In an optional embodiment, the calcination temperature is controlled at 500℃-800℃, and the calcination time is 5h-8h;

[0016] And / or, calcination is carried out in an oxygen atmosphere.

[0017] In an optional embodiment, the preparation process of the first raw material solution includes: dissolving lithium salt and zirconium salt together in water to prepare a salt solution with a total mass fraction of 40%-60%.

[0018] And / or, the second raw material solution includes an aluminum salt solution and a phosphoric acid solution, respectively, with the aluminum salt solution having a mass fraction of 40%-60% and the phosphoric acid solution having a mass fraction of 40%-60%, and the aluminum salt solution and the phosphoric acid solution are sprayed in simultaneously.

[0019] In an optional embodiment, a bottom-inlet spray fluidized bed is used for coating, and the inlet air temperature is controlled at 90℃-130℃, and the fan frequency is 40Hz-60Hz.

[0020] And / or, after preheating the ternary cathode material substrate for 10-30 minutes, the first raw material liquid and the second raw material liquid are sprayed sequentially. During the spraying of the first raw material liquid and the second raw material liquid, the nozzle pressure of the fluidized bed is controlled at 0.1MPa-0.3MPa and the peristaltic pump frequency is 10Hz-20Hz.

[0021] In an optional embodiment, the preparation process of the ternary cathode material matrix includes: mixing a nickel cobalt manganese hydroxide precursor and a lithium source, and then holding the mixture at 450℃-550℃ for 3h-7h in an oxygen-containing atmosphere, followed by holding it at 900℃-950℃ for 8h-12h.

[0022] Preferably, the molar ratio of lithium to total nickel, cobalt and manganese in the lithium source is controlled to be (1.03-1.06):1.

[0023] Thirdly, this disclosure provides a positive electrode sheet, including any of the modified ternary positive electrode materials in the foregoing embodiments or the modified ternary positive electrode materials prepared by any of the preparation methods in the foregoing embodiments.

[0024] Fourthly, this disclosure provides a lithium battery including the positive electrode sheet of the aforementioned embodiments.

[0025] This disclosure has the following beneficial effects: The modified ternary cathode material provided by this disclosure has a double coating layer, with an inner coating of Li2ZrO3 and an outer coating of AlPO4. The inner Li2ZrO3 is a fast conductor of lithium ions, which can improve the interfacial kinetics of lithium ions and improve the rate performance of the material; the outer AlPO4, through PO4... 3- With Al 3+ The strong covalent interactions between the particles effectively resist electrolyte corrosion, thereby reducing surface side reactions. Furthermore, the thermally stable AlPO4 coating further enhances the material's thermal stability. Therefore, the modified ternary cathode material provided in this disclosure can simultaneously improve particle surface stability and conductivity, which is beneficial for simultaneously improving the rate performance and cycle stability of the ternary material. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this disclosure and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 is a SEM image of the modified ternary cathode material prepared in Example 1;

[0028] Figure 2 is a SEM image of the modified ternary cathode material prepared in Example 2;

[0029] Figure 3 is a SEM image of the modified ternary cathode material prepared in Example 3;

[0030] Figure 4 shows the SEM image of the ternary cathode material prepared in Comparative Example 1.

[0031] Figure 5 shows the SEM image of the ternary cathode material prepared in Comparative Example 2. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions in the embodiments of this disclosure will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0033] This disclosure provides a modified ternary cathode material, comprising a ternary cathode material matrix, on which an inner coating layer and an outer coating layer are sequentially coated to form a double-coating structure. The inner coating layer contains Li₂ZrO₃ and is an ion-conducting layer; the outer coating layer contains AlPO₄ and is an inert layer. There is no clear boundary between the inner and outer coating layers, and the materials of the two coating layers are interpenetrating.

[0034] In some embodiments, the chemical formula of the ternary cathode material matrix is ​​LiNi. x Co y Mn z For O2, the values ​​of x, y, and z satisfy the above ranges, 0.6 < x < 0.7, 0.1 < y < 0.2, and 0.2 < z < 0.3, all suitable for forming a double coating layer to improve the stability and conductivity of the particle surface. Specifically, the chemical formula of the ternary cathode material matrix can be LiNi. 0.65 Co 0.10 Mn 0.25 O2, but not limited to this.

[0035] In some embodiments, the mass ratio of the total amount of the inner and outer coating layers to the ternary cathode material matrix is ​​(1-5):100, such as 1.0:100, 2.0:100, 2.5:100, 3.0:100, 3.5:100, 4.0:100, 5.0:100, etc., preferably (2.5-3.5):100. Controlling the total amount of the inner and outer coating layers within the above range is preferable, as it is beneficial for further improving the rate performance and cycle stability of the cathode material. The molar ratio of Li2ZrO3 to AlPO4 is (1-3):1, such as 1.0:1, 1.5:1, 2.0:1, 2.5:1, 3.0:1, etc. If the amount of AlPO4 is too small, it will affect the stability of the material, while if the amount of AlPO4 is too large, it will affect the rate performance of the material.

[0036] This disclosure also provides a method for preparing a modified ternary cathode material, comprising: forming an inner coating layer and an outer coating layer on a ternary cathode material substrate to prepare a modified ternary cathode material with a double-coating layer structure. The specific steps are as follows:

[0037] S1, Providing a ternary cathode material matrix

[0038] The matrix of ternary cathode materials can be commercially available or prepared in-house.

[0039] In some embodiments, the preparation process of the ternary cathode material matrix includes: mixing a nickel-cobalt-manganese hydroxide precursor and a lithium source, and sintering them in an oxygen-containing atmosphere. The ratio of nickel, cobalt, and manganese is controlled according to the chemical formula of the ternary cathode material matrix in the target product. The sintering process can be carried out in a segmented manner, first holding at 450℃-550℃ for 3h-7h, then holding at 900℃-950℃ for 8h-12h, and then pulverizing the material after natural cooling to obtain the matrix material.

[0040] Specifically, during the first stage of sintering, the sintering temperature can be controlled at 450℃, 480℃, 500℃, 520℃, 550℃, etc., and the holding time can be 3h, 4h, 5h, 6h, 7h, etc.; during the second stage of sintering, the sintering temperature can be controlled at 900℃, 910℃, 920℃, 930℃, 940℃, 950℃, etc., and the holding time can be 8h, 9h, 10h, 11h, 12h, etc.

[0041] Furthermore, by adjusting the amount of lithium source, the molar ratio of lithium to the total amount of nickel, cobalt, and manganese in the lithium source can be (1.03-1.06):1, such as 1.03:1, 1.04:1, 1.05:1, 1.06:1, etc., with a slight excess of lithium being preferable. Specifically, the lithium source can be lithium hydroxide, but it is not limited to this.

[0042] S2, Provide raw material liquid

[0043] A first feed solution for forming the inner coating layer is prepared, and a second feed solution for forming the outer coating layer is also prepared. The first feed solution can be a mixture of lithium and zirconium, or it can include a lithium salt solution and a zirconium source solution. The second feed solution includes an aluminum salt solution and a phosphoric acid solution. Since mixing the two solutions easily produces precipitation, it is advisable not to mix them in advance.

[0044] In some embodiments, the preparation process of the first raw material solution includes: dissolving lithium salt and zirconium salt together in water to prepare a salt solution with a total mass fraction of 40%-60%, controlling the concentration within the above range to facilitate the formation of a uniform coating. Specifically, the total mass fraction of lithium salt and zirconium salt in the first raw material solution can be 40%, 50%, 60%, etc.

[0045] In some embodiments, the second raw material solution is an aluminum salt solution and a phosphoric acid solution, wherein the mass fraction of the aluminum salt solution is 40%-60% and the mass fraction of the phosphoric acid solution is 40%-60%, and the aluminum salt solution and phosphoric acid solution are sprayed in simultaneously. The solvent for both the aluminum salt solution and the phosphoric acid solution can be water, and the mass fraction of the aluminum salt solution can be 40%, 50%, 60%, etc., and the mass fraction of the phosphoric acid solution can be 40%, 50%, 60%, etc.

[0046] S3. Coating using a spray fluidized bed.

[0047] A ternary cathode material substrate is placed in a spray fluidized bed chamber, and atomized first and second raw material solutions are sprayed sequentially. That is, the second raw material solution is sprayed after the first. Both the first and second raw material solutions can be pumped into the fluidized bed chamber and atomized using a peristaltic pump, allowing the atomized solution to fully contact and dry the fluidized single-crystal ternary material. After spraying the first raw material solution, Li and Zr salts can be uniformly deposited on the particle surface; after spraying the second raw material solution, Al and P salts can be simultaneously and uniformly deposited on the single-crystal particles.

[0048] In some embodiments, a bottom-inlet spray fluidized bed is used for coating, with the inlet air temperature controlled at 90℃-130℃ and the fan frequency at 40Hz-60Hz. By adjusting the inlet air temperature and fan frequency, the water in the solution evaporates rapidly, forming a coating layer. Specifically, the inlet air temperature can be 90℃, 100℃, 110℃, 120℃, 130℃, etc.; the fan frequency can be 40Hz, 50Hz, 60Hz, etc.

[0049] Furthermore, during operation, the ternary cathode material substrate can be preheated for 10-30 minutes before sequentially spraying the first and second raw material solutions. During the spraying of the first and second raw material solutions, the nozzle pressure of the fluidized bed is controlled at 0.1 MPa-0.3 MPa, and the peristaltic pump frequency is 10 Hz-20 Hz to ensure the solution is sprayed more evenly onto the cathode material, forming a uniform coating. Specifically, the preheating time can be 10 minutes, 20 minutes, 30 minutes, etc.; the nozzle pressure of the fluidized bed can be controlled at 0.1 MPa, 0.2 MPa, 0.3 MPa, etc.; and the peristaltic pump frequency can be 10 Hz, 15 Hz, 20 Hz, etc.

[0050] S4, calcination

[0051] After the spraying in step S3 is completed, the material is collected and calcined to obtain a double-layer coated single-crystal ternary cathode material.

[0052] In some embodiments, calcination is carried out in an oxygen atmosphere, with the calcination temperature controlled at 500℃-800℃ and the calcination time at 5h-8h. Too low a temperature is detrimental to the stability of the coating layer, while too high a temperature easily leads to interdiffusion of elements, causing changes in the form of each coating layer. By controlling the calcination temperature and time, the reaction is allowed to proceed fully, forming a double coating layer of Li₂ZrO₃ and AlPO₄. Specifically, the calcination temperature can be 500℃, 600℃, 700℃, 800℃, etc., and the calcination time can be 5h, 6h, 7h, 8h, etc.

[0053] This disclosure also provides a positive electrode sheet, including the modified ternary positive electrode material provided in this disclosure. By improving the ternary positive electrode material, it is beneficial to improve the rate performance and cycle stability of the material. Specifically, the positive electrode sheet includes a positive current collector, on which a positive active coating is formed, and the modified ternary positive electrode material is the main material of the positive active coating.

[0054] This disclosure provides a lithium battery, including a positive electrode sheet provided in this disclosure, and may also include a negative electrode sheet, an electrode liquid, etc. Due to the improvement of the positive electrode material, this lithium battery has better rate performance and cycle stability, and has good market application prospects.

[0055] The features and performance of this disclosure will be further described in detail below with reference to embodiments.

[0056] It should be noted that the precursor Ni used in the following embodiments and comparative examples 0.65 Co 0.10 Mn 0.25 (OH)2 is a commercially available raw material purchased from Yibin Guangyuan Lithium Battery Materials Co., Ltd., model number Y1PM63703.

[0057] Example 1

[0058] This embodiment provides a method for preparing a modified ternary cathode material, the steps of which are as follows:

[0059] The precursor Ni with stoichiometry 0.65 Co 0.10 Mn 0.25 (OH)₂ and LiOH (with 5% lithium excess, i.e., the molar ratio of lithium to total nickel, cobalt, and manganese in LiOH is 1.05:1) are mixed evenly and placed in a box furnace with an oxygen concentration ≥98%. The mixture is heated to 500℃ at a heating rate of 4℃ / min and held for 5 hours. Then, the temperature is increased to 930℃ and held for 10 hours. After natural cooling, the material is pulverized to obtain the matrix material. 5 kg of the collected material is placed in a bottom-inlet fluidized bed chamber with an inlet air temperature of 100℃ and a fan frequency of 50Hz to preheat the material for 15 minutes.

[0060] The raw materials were weighed according to a total coating material (Li₂ZrO₃ and AlPO₄) of 1 wt%, with a molar ratio of Li₂ZrO₃ to AlPO₄ of 2:1. A 50% salt solution (solution A) was prepared by dissolving lithium nitrate and zirconium nitrate pentahydrate in water, and a 50% salt solution (solution B) was prepared by dissolving aluminum nitrate nonahydrate in water. A 50% solution (solution C) was prepared by dispersing phosphoric acid (85 wt% aqueous solution) in water. The nozzle pressure of the fluidized bed was adjusted to 0.2 MPa, and the peristaltic pump frequency was set to 15 Hz. Solution A was pumped into the fluidized bed cavity. After solution A was pumped out, solutions B and C were simultaneously pumped in. Finally, the collected material was calcined at 750°C for 5 hours under an oxygen atmosphere and naturally cooled to obtain the powder of Example 1.

[0061] Figure 1 shows the SEM image of the powder prepared in Example 1. It can be seen that the particles are relatively dispersed and the surface is relatively smooth.

[0062] Performance Testing: The powder from Example 1 was mixed with a conductive agent (carbon black) and a binder (PVDF) in a 9:5:5 ratio in N-methylpyrrolidone (NMP) to form a slurry. This slurry was coated onto an aluminum foil current collector, dried, and cut to form a positive electrode sheet. A button cell was assembled using lithium metal as the negative electrode and 1M LiPF6 dissolved in EC / EMC / DMC (volume ratio 1:1:1) as the electrolyte. The electrochemical performance of the positive electrode material was tested within a voltage range of 2.8–4.5V. The chemical properties are shown in Table 1. The rate capacity was measured at 25°C, and the cycle retention was measured at 45°C.

[0063] Example 2

[0064] The only difference from Example 1 is that the total coating (Li2ZrO3 and AlPO4) is 3 wt% of the matrix material. The SEM image of the powder prepared in Example 2 is shown in Figure 2. It can be seen that the particles are relatively dispersed and the particle surface is relatively smooth but contains a small amount of small particles. Performance test: The test method is the same as in Example 1, and the chemical properties are shown in Table 1.

[0065] Example 3

[0066] The only difference from Example 1 is that the total coating (Li2ZrO3 and AlPO4) is 5 wt% of the matrix material. The SEM image of the powder prepared in Example 3 is shown in Figure 3. It can be seen that the particles are relatively dispersed, and the particle surface is relatively smooth but contains obvious small particles. Performance testing: The testing method is the same as in Example 1, and the chemical properties are shown in Table 1.

[0067] Example 4

[0068] The only difference from Example 1 is that the molar ratio of Li₂ZrO₃ to AlPO₄ is 0.5:1. Performance testing: The test method is the same as in Example 1, and the chemical properties are shown in Table 1.

[0069] Example 5

[0070] The only difference from Example 1 is that the molar ratio of Li₂ZrO₃ to AlPO₄ is 1:1. Performance testing: The test method is the same as in Example 1, and the chemical properties are shown in Table 1.

[0071] Example 6

[0072] The only difference from Example 1 is that the molar ratio of Li₂ZrO₃ to AlPO₄ is 1:2. Performance testing: The test method is the same as in Example 1, and the chemical properties are shown in Table 1.

[0073] Comparative Example 1

[0074] The only difference from Example 1 is that it does not coat Li2ZrO3 and AlPO4. The specific steps are as follows: Ni, the precursor in stoichiometric ratio... 0.65 Co 0.10 Mn 0.25 (OH)2 and LiOH (5% lithium excess) were mixed evenly and placed in a box furnace with an oxygen concentration ≥98%. The mixture was heated to 500℃ at a heating rate of 4℃ / min and held for 5 hours. Then the mixture was heated to 930℃ and held for 10 hours. After natural cooling, the material was pulverized to obtain the powder of Comparative Example 1.

[0075] The SEM image of the cathode powder prepared in Comparative Example 1 is shown in Figure 4. It can be seen that the particles are well dispersed and the particle surface is relatively smooth. Performance testing: The testing method is the same as in Example 1, and the chemical properties are shown in Table 1.

[0076] Comparative Example 2

[0077] This comparative example provides a dry mixing and coating process, the specific steps of which are as follows:

[0078] The precursor Ni with stoichiometry 0.65 Co 0.10 Mn 0.25 (OH)₂ and LiOH (5% lithium excess) were mixed evenly and placed in a box furnace with an oxygen concentration ≥98%. The mixture was heated to 500°C at a heating rate of 4°C / min and held for 5 hours. Then, the temperature was increased to 930°C and held for 10 hours. After natural cooling, the material was pulverized. 5 kg of the collected material was mixed evenly with lithium carbonate, nano-zirconium oxide, nano-alumina, and nano-lithium phosphate in a specific ratio. The mixture was then calcined at 750°C for 5 hours under an oxygen atmosphere and allowed to cool naturally to obtain the powder of Comparative Example 2. The molar amounts of lithium, zirconium, aluminum, and phosphate added were consistent with those in Example 1.

[0079] The SEM image of the powder in Comparative Example 2 is shown in Figure 5. The particles are well dispersed, but there are very obvious small particles on the surface. Performance testing: The test method is the same as in Example 1, and the chemical properties are shown in Table 1.

[0080] Comparative Example 3

[0081] The only difference from Example 1 is that only liquid A is sprayed, and liquids B and C are not sprayed. Performance testing: The test method is the same as in Example 1, and the chemical properties are shown in Table 1.

[0082] Comparative Example 4

[0083] The only difference from Example 1 is that only liquids B and C are sprayed, while liquid A is not sprayed. Performance testing: The testing method is the same as in Example 1, and the chemical properties are shown in Table 1.

[0084] Table 1. Electrochemical performance of different comparative examples and embodiments

[0085] As can be seen, this disclosure achieves kilogram-level uniform coating of single-crystal ternary cathode materials using a spray-type fluidized bed device, with the 3wt% Li2ZrO3 and AlPO4 coating exhibiting the best performance. The method and process provided in this disclosure are simple and effective, simultaneously improving the rate performance and cycle stability of ternary materials, and thus possess high practicality.

[0086] The above are merely preferred embodiments of this disclosure and are not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure. Industrial applicability

[0087] The modified ternary cathode material disclosed herein has a double coating layer: an inner layer coated with Li₂ZrO₃ and an outer layer coated with AlPO₄. The inner Li₂ZrO₃ layer is a fast lithium-ion conductor, which can improve the interfacial kinetics of lithium ions and enhance the rate performance of the material; the outer AlPO₄ layer... 3- The strong covalent interaction between Al3+ and AlPO4 effectively resists electrolyte corrosion, thereby reducing surface side reactions. Furthermore, the thermally stable AlPO4 coating further enhances the material's thermal stability. Therefore, the modified ternary cathode material provided in this disclosure can simultaneously improve particle surface stability and conductivity, which is beneficial for simultaneously improving the rate performance and cycle stability of ternary materials. Moreover, the double coating layer is easy to form, demonstrating good industrial applicability.

Claims

1. A modified ternary cathode material, characterized in that, The material includes a ternary cathode material matrix, on which an inner coating layer and an outer coating layer are sequentially coated. The inner coating layer contains Li2ZrO3, and the outer coating layer contains AlPO4.

2. The modified ternary cathode material according to claim 1, characterized in that, The total amount of the inner coating layer and the outer coating layer to the mass ratio of the ternary cathode material matrix is ​​(1-5):100, preferably (2.5-3.5):100; And / or, the molar ratio of Li2ZrO3 to AlPO4 is (1-3):1; And / or, the ternary positive electrode material matrix has a chemical formula of LiNi x Co y Mn z O2, 0.6 < x < 0.7, 0.1 < y < 0.2, 0.2 < z < 0.

3.

3. A method for preparing the modified ternary cathode material according to any one of claims 1-2, characterized in that, include: The inner coating layer and the outer coating layer are formed on the ternary cathode material matrix.

4. The method of claim 3, wherein the modified ternary cathode material is prepared by the steps of: preparing a precursor material by mixing a lithium source, a transition metal source, and a carbon source; and calcining the precursor material in a non-oxidizing atmosphere. include: A first raw material liquid for forming the inner coating layer and a second raw material liquid for forming the outer coating layer are prepared. The ternary cathode material matrix is ​​placed in a spray fluidized bed cavity, and the atomized first raw material liquid and the second raw material liquid are sprayed sequentially, followed by calcination.

5. The method for preparing a modified ternary cathode material according to claim 4, characterized in that, The calcination temperature is controlled at 500℃-800℃, and the calcination time is 5h-8h; And / or, calcination is carried out in an oxygen atmosphere.

6. The method for preparing a modified ternary cathode material according to claim 4, characterized in that, The preparation process of the first raw material solution includes: dissolving lithium salt and zirconium salt together in water to prepare a salt solution with a total mass fraction of 40%-60%; And / or, the second raw material solution is an aluminum salt solution and a phosphoric acid solution, wherein the mass fraction of the aluminum salt solution is 40%-60% and the mass fraction of the phosphoric acid solution is 40%-60%, and the aluminum salt solution and the phosphoric acid solution are sprayed in simultaneously.

7. The method for preparing a modified ternary cathode material according to claim 6, characterized in that, The coating is carried out using a bottom-inlet spray fluidized bed, with the inlet air temperature controlled at 90℃-130℃ and the fan frequency at 40Hz-60Hz. And / or, after preheating the ternary cathode material matrix for 10-30 minutes, the first raw material liquid and the second raw material liquid are sprayed sequentially. During the spraying of the first raw material liquid and the second raw material liquid, the nozzle pressure of the fluidized bed is controlled at 0.1MPa-0.3MPa, and the peristaltic pump frequency is 10Hz-20Hz.

8. The method for preparing the modified ternary cathode material according to claim 3, characterized in that, The preparation process of the ternary cathode material matrix includes: mixing a nickel cobalt manganese hydroxide precursor and a lithium source, and then holding the mixture at 450℃-550℃ for 3h-7h in an oxygen-containing atmosphere, followed by holding it at 900℃-950℃ for 8h-12h. Preferably, the molar ratio of lithium to total nickel, cobalt and manganese in the lithium source is controlled to be (1.03-1.06):

1.

9. A positive electrode sheet characterized by comprising: This includes the modified ternary cathode material according to any one of claims 1-2 or the modified ternary cathode material prepared by the preparation method according to any one of claims 3-8.

10. A lithium battery, characterized by, Includes the positive electrode sheet as described in claim 9.

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