A ternary cathode material, a preparation method thereof, and a lithium battery

Abstract

The present invention discloses a ternary cathode material, a preparation method thereof, and a lithium battery, relating to the technical field of cathode materials. Since the polycrystalline ternary cathode material is composed of multiple primary particles assembled into secondary particles, the size of the primary particles, the arrangement angle θ, the porosity ε, and the distribution ratio of large and small particles in the ternary cathode material all have a significant impact on the internal stress accumulation and yield limit of the secondary particles caused by anisotropic volume shrinkage and expansion during the charge and discharge process of the primary particles. The above product parameters interact and affect each other. By using the above parameters to construct an expression for the stability parameter F of the ternary cathode material and making F satisfy a specific range, the stability of the structure of the ternary cathode material can be improved, stress fatigue can be resisted, the generation of microcracks can be reduced, and it is beneficial to improving the cycle performance of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of cathode materials, and in particular, to a ternary cathode material, a preparation method thereof, and a lithium battery. Background Art

[0002] The ternary cathode material LiNi x Co y Mn z O2 (x≥0.6) has the advantages of high capacity, low cost, and large-scale production, and is one of the best materials for the cathode of high specific energy lithium batteries. During the cycling process of polycrystalline ternary cathode materials, under the action of electrochemical-mechanical coupling, the polycrystalline cathode materials will break, and the fracture at the grain boundaries occurs most frequently. The generation of cracks is due to the stress accumulation exceeding the yield limit of the particles, and cracks are generated between the grain boundaries of the grains; during the cycling process, the cracks gradually extend from the inside of the secondary particles to the surface, and even pulverize the particles.

[0003] Among them, the microcracks of the ternary cathode material provide channels for the electrolyte to penetrate into the secondary particles, exacerbate the side reaction between the inside of the material and the electrolyte, and make the highly active Ni on the surface of the material inside the particles 4+ react to form the rock salt phase of NiO, which not only consumes the electrolyte and the active material, but also forms an electron and ion isolation region inside the particles, increases the resistance of the material, and accelerates the decline of the capacity during the cycling process. In addition, the anisotropic volume shrinkage and expansion that occur during the charge and discharge process of the primary particles have a huge impact on the stress accumulation and yield limit inside the secondary particles.

[0004] Therefore, there is an urgent need to provide a ternary cathode material that can withstand stress fatigue to reduce the generation of microcracks and improve the cycling performance of the battery.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a ternary cathode material, a preparation method thereof, and a lithium battery, aiming to reduce the generation of microcracks in the cathode material and improve the cycling performance of the battery.

[0007] The present invention is implemented as follows:

[0008] In the first aspect, the present invention provides a ternary cathode material, and the ternary cathode material satisfies:

[0009] F = ;

[0010] 0.5° ≤ F ≤ 40°;

[0011] wherein, F represents the stability parameter of the ternary cathode material, and the unit is °;

[0012] Represents the maximum Feret diameter of the primary particle profile corresponding to the primary particle in the secondary particle profile of the ternary cathode material, with the unit of μm;

[0013] Represents the minimum circumscribed circle diameter of the secondary particle profile corresponding to the primary particle, with the unit of μm;

[0014] Represents the angle between the radial direction radius of the minimum circumscribed circle of the secondary particle profile passing through the midpoint of the maximum Feret diameter of the primary particle profile in the corresponding section and the maximum Feret diameter in the direction with the shorter distance from the primary particle to the minimum circumscribed circle, with the unit of °;

[0015] Represents the porosity, , Represents the true density, Represents the tap density, and The units are both g / cm 3 ;

[0016] and respectively represent the particle sizes corresponding to the cumulative volume of the ternary cathode material particles reaching 90% and 10% for the corresponding batches, is the particle size corresponding to the maximum y value in the corresponding particle size distribution diagram, , , The units of are all μm;

[0017] n represents the number of primary particles selected from the same secondary particle or different secondary particles, and n≥40.

[0018] In an optional embodiment, the ternary cathode material satisfies at least one of the following characteristics A1-K1:

[0019] Characteristic A1: 0.1≤ ≤1.0;

[0020] Characteristic B1: 0°≤ ≤70°;

[0021] Characteristic C1: 0.5°≤ ≤20°; [[ID=6l]]

[0022] Characteristic D1: 0.5≤ ≤20;

[0023] Characteristic E1: 0.1≤ ≤6.5;

[0024] Characteristic F1: ≤5μm, 2μm≤ ≤25 μm, 0.05 ≤ ≤ 0.5;

[0025] Feature G1: 0° ≤ ≤ 110°;

[0026] Feature H1: 0.1 ≤ ≤ 0.4;

[0027] Feature I1: 3 μm ≤ ≤ 15 μm, 6 μm ≤ ≤ 25 μm, 2 μm ≤ ≤ 8 μm;

[0028] Feature J1: 4.4 g / cm 3 ≤ ≤ 5.1 g / cm 3 , and 3.15 g / cm 3 ≤ ≤ 3.85 g / cm 3 ;

[0029] Feature K1: The selection of n primary particles needs to meet the following conditions: <0.1 and 0.1 ≤ , and the selection of <0.1 primary particles is 2.5 - 3.5 times the number of corresponding primary particles of 0.1 ≤ the corresponding number of primary particles.

[0030] In a second aspect, the present invention also provides a method for preparing a ternary cathode material, including: performing a coprecipitation reaction using a cobalt source, a nickel source, and a manganese source to obtain a precursor intermediate;

[0031] Adjusting the pH value of the precursor intermediate to 8 - 9, then mixing and reacting with a guiding agent, and then mixing and reacting with an initiator, and then raising the pH value to continue the coprecipitation reaction using the cobalt source, the nickel source, and the manganese source, and performing solid-liquid separation to obtain a precursor;

[0032] Mixing and calcining the precursor with a lithium source.

[0033] In an optional embodiment, the process of preparing the precursor using the precursor intermediate satisfies at least one of the following features A2 - E2:

[0034] Feature A2: The guiding agent is selected from at least one of monoammonium allyl phosphate, vinyl phosphoric acid, cis-propenyl phosphoric acid, and allyl phosphoric acid;

[0035] Feature B2: Controlling the addition concentration of the guiding agent to be 0.7 mol / L - 1.0 mol / L;

[0036] Feature C2: The reaction temperature with the initiator is 15°C - 35°C, and the reaction time is 1.5 h - 2.5 h;

[0037] Feature D2: During the reaction with the initiator and the guiding agent, ultrasonic oscillation is carried out, and the frequency of ultrasonic oscillation is 15 kHz - 30 kHz;

[0038] Feature E2: The pH value of the precursor intermediate is adjusted to 8 - 9 using an acid solution, and the acid solution is selected from at least one of sulfuric acid solution, acetic acid solution, and citric acid solution.

[0039] In an alternative embodiment, the process of preparing the precursor from the precursor intermediate satisfies at least one of the following features A3 - D3:

[0040] Feature A3: The initiator is selected from at least one of 2,2 - azobis(2 - methylpropylimid) dihydrochloride and azobisisobutyramidine hydrochloride;

[0041] Feature B3: The addition concentration of the initiator is controlled to be 4 g / L - 6 g / L;

[0042] Feature C3: The reaction temperature with the initiator is 15°C - 35°C, and the reaction time is 1.5 h - 2.5 h;

[0043] Feature D3: After the reaction with the initiator is completed, the pH value is raised to 11.0 - 11.5, and a nickel - cobalt - manganese mixed salt solution, a precipitant solution, and a complexing agent solution are introduced for coprecipitation reaction for 6 h - 20 h. After solid - liquid separation, washing, and drying, the precursor is obtained.

[0044] In an alternative embodiment, the process of preparing the precursor intermediate includes: introducing a nickel - cobalt - manganese mixed salt solution, a precipitant solution, and a complexing agent solution into a reaction kettle with a bottom liquid, and stirring and reacting for 2 h - 3 h; wherein, the nickel - cobalt - manganese mixed salt solution is obtained by mixing a nickel source, a cobalt source, and a manganese source, and the molar ratio of nickel element, cobalt element, and manganese element is 5:2:3, 1:1:1, 4:2:4, 6:2:2, 8:1:1, or (86 - 96):(2 - 9):(2 - 5);

[0045] And / or, during the process of preparing the precursor intermediate, the reaction temperature is controlled to be 45°C - 60°C, and the stirring rate is 400 rpm - 700 rpm.

[0046] In an alternative embodiment, the process of preparing the precursor intermediate satisfies at least one of the following features A4 - C4:

[0047] Feature A4: The concentration of the nickel - cobalt - manganese mixed salt solution is 1.5 mol / L - 2.2 mol / L, and the feeding rate is 25 mL / min - 35 mL / min;

[0048] Feature B4: The precipitant solution is a sodium hydroxide solution with a concentration of 10 mol / L - 12 mol / L. By adjusting the feeding rate of the sodium hydroxide solution, the pH value of the solution in the reaction kettle is maintained at 11.0 - 11.5;

[0049] Feature C4: The complexing agent solution is an ammonia water solution. By adjusting the feeding rate of the ammonia water solution, the ammonia concentration in the solution in the reaction kettle is 0.7 mol / L - 1.1 mol / L.

[0050] In an alternative embodiment, after mixing the precursor with the lithium source, a ternary cathode material intermediate is obtained through two-step calcination;

[0051] The ternary cathode material intermediate is mixed and calcined with the coating agent.

[0052] In an alternative embodiment, the process of preparing the ternary cathode material using the precursor satisfies at least one of the following features A5 - G5:

[0053] Feature A5: The two-step calcination includes: first, maintaining the temperature at 400°C - 550°C for 3 h - 5 h, and then heating to 750°C - 800°C and maintaining the temperature for 12 h - 15 h;

[0054] Feature B5: Controlling the molar ratio of lithium to the total amount of nickel, cobalt, and manganese to be (1.03 - 1.07):1;

[0055] Feature C5: Mixing and grinding the precursor and the lithium source before performing the two-step calcination;

[0056] Feature D5: The lithium source is selected from at least one of lithium hydroxide, lithium carbonate, and lithium oxalate;

[0057] Feature E5: The coating agent is selected from at least one of V2O5, Al2O3, ZrO2, TiO2, SnO2, ZnO, MgO, RuO2, La2O3, CeO2, Co3O4, SiO2, FePO4, Li3PO4, Li2MnO3, LiAlO2, Li2TiO3, Li2ZrO3, Li3VO4, Li2SiO3, AlF3, LaF3, and MgF2;

[0058] Feature F5: The mass ratio of the coating agent to the ternary cathode material intermediate is (5 - 10):100;

[0059] Feature G5: The calcination temperature of the ternary cathode material intermediate and the coating agent is 550°C - 650°C, and the calcination time is 3 h - 8 h.

[0060] In a third aspect, the present invention further provides a lithium battery, including the ternary cathode material provided in any of the above embodiments or the ternary cathode material prepared by the preparation method provided in any of the above embodiments.

[0061] The present invention has the following beneficial effects: Since the polycrystalline ternary cathode material is composed of multiple primary particles assembled into secondary particles, the size of the primary particles , the arrangement angle θ, the porosity ε, and the distribution ratio of large and small particles in the ternary cathode material all have a significant impact on the internal stress accumulation and yield limit in the secondary particles caused by the anisotropic volume shrinkage and expansion during the charge and discharge process of the primary particles. The above product parameters have a coordinated influence on each other. By using the above parameters to construct an expression for the stability parameter F of the ternary cathode material and making F satisfy a specific range, the stability of the structure of the ternary cathode material can be improved, stress fatigue can be resisted, the generation of microcracks can be reduced, and it is beneficial to improve the cycle performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0063] Figure 1 SEM cross-sectional view of the secondary particles of the ternary cathode material provided in Embodiment 1 of the present invention;

[0064] Figure 2 SEM cross-sectional view of the secondary particles of the ternary cathode material provided in Comparative Example 1 of the present invention;

[0065] Figure 3 For the primary particles, secondary particles, d R and d r and in the product of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0066] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0067] To better evaluate the performance of the ternary cathode material in resisting stress fatigue and provide a ternary cathode material with high cycle performance and low capacity attenuation rate, the present invention comprehensively considers the size of the primary particles , the arrangement angle θ, the porosity ε, and the distribution ratio of large and small particles in the ternary cathode material Construct an expression for the stability parameter F of the ternary cathode material using parameters such as , and regulate its value range by controlling the structure of the ternary cathode material.

[0068] The expression for constructing the stability parameter F of the ternary cathode material is as follows:

[0069] F = ;

[0070] The ternary cathode material provided in the embodiments of the present invention satisfies: 0.5° ≤ F ≤ 40°, such as 0.5°, 1.0°, 3.0°, 5.0°, 8.0°, 10.0°, 13.0°, 15.0°, 18.0°, 20.0°, 23.0°, 25.0°, 28.0°, 30.0°, 33.0°, 35.0°, 38.0°, 40.0°, etc., and the unit of F is °.

[0071] Explanation of each parameter in the expression for the stability parameter F of the ternary cathode material:

[0072] Represents the maximum Feret diameter (hereinafter referred to as the diameter) of the primary particle profile corresponding to the primary particle in the secondary particle profile of the ternary cathode material, and the unit is μm; Represents the minimum circumscribed circle diameter (hereinafter referred to as the diameter) of the secondary particle profile corresponding to the primary particle, and the unit is μm. Then represents the relative size of the primary particle to the secondary particle. The larger this value is, the greater the impact of the stress accumulation of the primary particle on the secondary particle.

[0073] Represents the angle between the radial direction radius of the minimum circumscribed circle of the secondary particle profile passing through the midpoint of the maximum Feret diameter of the primary particle profile in the corresponding profile and the maximum Feret diameter in the direction with the shorter distance from the primary particle to the minimum circumscribed circle, and the unit is °. Represents the deviation angle of the radial arrangement of the primary particle in the secondary particle. The larger the deviation angle is, the less conducive it is to the relief of stress, which will lead to stress concentration.

[0074] Specifically, 、 And , are obtained by analyzing the scanning electron microscope image (SEM) of the cathode material profile through imagej. For the specific test process, refer to the specific embodiments later.

[0075] Represents the porosity. The increase of this value indicates more gaps between particles, which is beneficial to the relief of stress. However, if this value is too large and there are too many voids, it is also not conducive to the stability of the secondary particle structure. , Represents the true density, Represents the tap density, and The unit is g / cm 3 , and the porosity can be calculated by detecting the true density and the compacted density .

[0076] and respectively represent the particle sizes corresponding to the cumulative volume of 90% and 10% of the ternary cathode material particles in the corresponding batches is the particle size corresponding to the maximum y value in the corresponding particle size distribution diagram 、 、 The unit of all is μm 、 、 are obtained by a laser particle size analyzer refers to the particle size corresponding to the maximum y value on the particle size distribution curve of the normal distribution, and its specific value is generally less than . represents the distribution ratio of large and small particles on both sides of the particle size Dvmax in the particle size distribution diagram. The larger the secondary particles, the easier it is to generate concentrated stress and the easier it is to exceed the yield limit and cause rupture

[0077] n represents the number of primary particles selected from the same secondary particle or different secondary particles, n≥40, such as 40, 60, 80, 100, 120, 150, 180, 200, etc., and the number can also be more to improve the detection accuracy. In the preferred embodiment, the selection of n primary particles needs to meet the following conditions <0.1 and 0.1≤ , and the selection of <0.1 of the number of primary particles is 2.5-3.5 times (such as 2.5 times, 2.8 times, 3.0 times, 3.2 times, 3.5 times, etc.) of the corresponding number of primary particles of 0.1≤

[0078] It should be noted that since the polycrystalline ternary cathode material is assembled from multiple primary particles to form secondary particles, the size 、arrangement angle θ, porosity ε of the primary particles, and the distribution ratio of large and small particles in the ternary cathode material , all have a significant impact on the internal stress accumulation and yield limit of the secondary particles caused by the anisotropic volume shrinkage and expansion during the charge and discharge process of the primary particles. At the same time, the above product parameters have a coordinated influence on each other. For the determined particles, if is large, it is not conducive to stress relief, if is small, it is relatively conducive to stress relief; if is smaller, it is not conducive to stress relief, if ​The larger it is, the more conducive it is to stress relief. However, if it is too large, it will cause capacity loss and is not conducive to the structural stability. At the same time reflects the proportion of large and small particles in the secondary particles. The larger this value is, the more large particles there are in the secondary particles and the easier they are to break. Based on the above description, Within the specified range, the structural stability of the ternary cathode material is relatively good.

[0079] In some embodiments, it is appropriate to control each parameter in the expression of the stability parameter F of the ternary cathode material within a certain range:

[0080] 0.1 ≤ ≤ 1.0, represents the average value of all selected particles and the value of can be 0.1, 0.3, 0.5, 0.8, 1.0, etc. If the value of

[0081] 0° ≤ ≤ 70°, represents the average value of all selected particles and the average value can be 0°, 5°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, etc.

[0082] 0.5° ≤ ≤ 20°, When the value of

[0083] is within this range, it is more conducive to stress relief. Specifically, the value of ≤ 20, can reflect the proportion of large and small particles in the secondary particles. If the value is too large, it is easy to break. Specifically, the value of

[0084] 0.1 ≤ ≤ 6.5, If the value of is too large, it will affect the structural stability. If the value is too small, it is not conducive to stress relief. Specifically,

[0085] ≤5 μm, 2 μm ≤ ≤25 μm, 0.05 ≤ ≤0.5. 、 、 Taking values within the above ranges is more conducive to stress relief. Specifically, The value of can be 0.1 μm, 0.5 μm, 1.0 μm, 2.0 μm, 3.0 μm, 4.0 μm, 5.0 μm, etc.; The value of can be 2 μm, 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, 23 μm, 25 μm, etc.; The value of can be 0.05, 0.08, 0.10, 0.20, 0.30, 0.40, 0.50, etc.

[0086] 0° ≤ ≤110°, If the value of is too large, it is not conducive to stress relief. The specific values can be 0°, 5°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, 100°, 110°, etc.

[0087] 0.1 ≤ ≤0.4, If the value is too large, it will cause capacity loss and is not conducive to the stability of the structure. If the value is too small, it is not conducive to stress release. The value can be 0.1, 0.2, 0.3, 0.4, etc.

[0088] 3 μm ≤ ≤15 μm, 6 μm ≤ ≤25 μm, 2 μm ≤ ≤8 μm. 、 、 Taking values within the above ranges is more conducive to stress release. Specifically, The value of can be 3 μm, 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, etc.; The value of can be 6 μm, 10 μm, 15 μm, 20 μm, 25 μm, etc.; The value of can be 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, etc.

[0089] 4.4 g / cm 3 ≤ ≤5.1 g / cm 3 and 3.15 g / cm 3 ≤ ≤3.85 g / cm3 . 、 Taking values within the above range can make the value more appropriate, which is beneficial to stress release and does not affect the structural stability. Specifically, the value of can be 4.4 g / cm 3 、4.5 g / cm 3 、4.6 g / cm 3 、4.7 g / cm 3 、4.8 g / cm 3 、4.9 g / cm 3 、5.0 g / cm 3 、5.1 g / cm 3 etc.; the value of can be 3.15 g / cm 3 、3.20 g / cm 3 、3.30 g / cm 3 、3.40 g / cm 3 、3.50 g / cm 3 、3.60 g / cm 3 、3.70 g / cm 3 、3.80 g / cm 3 、3.85 g / cm 3 etc.

[0090] The embodiment of the present invention also provides a preparation method of a ternary cathode material, and the steps are as follows:

[0091] S1. Prepare a precursor intermediate

[0092] Perform a coprecipitation reaction using a cobalt source, a nickel source, and a manganese source in the presence of a precipitating agent and a complexing agent to obtain a precursor intermediate, which is in the form of a slurry. In the actual operation process, a nickel-cobalt-manganese mixed salt solution, a precipitating agent solution, and a complexing agent solution are introduced into a reaction kettle with a bottom liquid, and stirred and reacted for 2 h - 3 h (such as 2.0 h, 2.5 h, 3.0 h, etc.), and the feeding of the three solutions is stopped.

[0093] In some embodiments, the nickel-cobalt-manganese mixed salt solution is obtained by mixing a nickel source, a cobalt source, a manganese source, and a solvent, and the molar ratio of nickel, cobalt, and manganese elements is 5:2:3, 1:1:1, 4:2:4, 6:2:2, 8:1:1, or (86-96):(2-9):(2-5). The nickel-cobalt-manganese molar ratio can be any one of the above, such as 5:2:3, 1:1:1, 4:2:4, 6:2:2, 8:1:1, 86:9:5, 88:8:4, 90:7:3, 92:5:3, 96:2:2, etc. The type of solvent is not limited, such as it can be water; the cobalt source is at least one of cobalt sulfate and its hydrates, the nickel source is at least one of nickel sulfate and its hydrates, and the manganese source is at least one of manganese sulfate and its hydrates. The concentration of the nickel-cobalt-manganese mixed salt solution is 1.5 mol / L - 2.2 mol / L, such as it can be 1.5 mol / L, 1.8 mol / L, 2.0 mol / L, 2.2 mol / L, etc.; the feeding rate is 25 mL / min - 35 mL / min, such as it can be 25 mL / min, 28 mL / min, 30 mL / min, 32 mL / min, 35 mL / min, etc. By regulating the concentration and feeding rate of the nickel-cobalt-manganese mixed salt solution, it is more appropriate to regulate the growth rate of solid particles and improve the uniformity of the product.

[0094] In some embodiments, the precipitating agent solution can be a sodium hydroxide solution, and the concentration of the sodium hydroxide solution can be 10 mol / L - 12 mol / L, such as it can be 10 mol / L, 11 mol / L, 12 mol / L, etc. By adjusting the feeding rate of the sodium hydroxide solution, the pH value of the solution in the reaction kettle is maintained at 11.0 - 11.5, such as it can be 11.0, 11.1, 11.2, 11.3, 11.4, 11.5, etc. The complexing agent solution can be an ammonia water solution. By adjusting the feeding rate of the ammonia water solution, the ammonia concentration in the solution in the reaction kettle is 0.7 mol / L - 1.1 mol / L, such as it can be 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, etc. By regulating the pH value and ammonia concentration of the solution in the reaction kettle to meet the requirements of the coprecipitation reaction, it is more appropriate to regulate the precipitation rate.

[0095] In some embodiments, during the process of preparing the precursor intermediate, the reaction temperature is controlled at 45°C - 60°C, such as it can be 45°C, 50°C, 55°C, 60°C, etc.; the stirring rate is 400 rpm - 700 rpm, such as it can be 400 rpm, 500 rpm, 600 rpm, 700 rpm, etc.

[0096] It should be noted that the ammonia concentration, reaction pH value, feeding rate, and stirring rate all affect the looseness of the secondary particles, the sizes of the secondary particles and the primary particles. Therefore, the particle size distribution, its looseness, and the size of the primary particles of the material are regulated by adjusting the reaction parameters.

[0097] S2. Preparation of the precursor

[0098] The pH value of the precursor intermediate obtained in step S1 is adjusted to 8 - 9, and then it is mixed and reacted with the guiding agent, and then mixed and reacted with the initiator. After that, the pH value is increased, and the coprecipitation reaction is continued using the cobalt source, nickel source, and manganese source. Solid-liquid separation is carried out to obtain the precursor. By adding the guiding agent and the initiator, the grain arrangement can be regulated, the ordered arrangement can be increased, and the size of the primary particles can be made more controllable.

[0099] In some embodiments, the guiding agent is selected from at least one of monoammonium allyl phosphate, vinyl phosphonic acid (VPA), cis-propenyl phosphonic acid (cPPA), and allyl phosphonic acid (APA). The guiding agent can be any one or several of the above. The addition concentration of the guiding agent is controlled to be 0.7 mol / L - 1.0 mol / L, such as 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, etc. The reaction temperature with the guiding agent is 15°C - 35°C, such as 15°C, 20°C, 25°C, 30°C, 35°C, etc.; the reaction time with the guiding agent is 1.5 h - 2.5 h, such as 1.5 h, 1.8 h, 2.0 h, 2.3 h, 2.5 h, etc.

[0100] In some embodiments, the initiator is selected from at least one of 2,2-azobis(2-methylpropylimid) dihydrochloride and azobisisobutyramidine hydrochloride (V-50). The initiator can be any one or several of the above. The addition concentration of the initiator is controlled to be 4 g / L - 6 g / L, such as 4.0 g / L, 4.5 g / L, 5.0 g / L, 5.5 g / L, 6.0 g / L, etc. The reaction temperature with the initiator is 15°C - 35°C, such as 15°C, 20°C, 25°C, 30°C, 35°C, etc.; the reaction time is 1.5 h - 2.5 h, such as 1.5 h, 1.8 h, 2.0 h, 2.3 h, 2.5 h, etc.

[0101] It should be noted that during the precursor precipitation process, the unsaturated transition metal atoms exposed on the crystal plane of the precursor particles (010) can form a strong coordination interaction with the phosphate group of the guiding agent to form an insoluble soap adsorbed on the crystal plane. In addition, the outward double bonds in the guiding agent will polymerize with the outward double bonds on the (010) crystal plane in the free grains under the action of the initiator, guiding the grains to be orderly arranged and reducing the angle of the primary particles deviating from the radial direction of the minimum circumscribed circle of the secondary particles in the secondary particles. Due to the addition of the guiding agent, the adsorption of metal ammonia complex ions on the (010) crystal plane is hindered, the growth trend of the

[010] crystal direction is reduced, and the growth of the grains in the

[001] direction is promoted. At the same time, this process increases the orderly arrangement of the grains.

[0102] In some embodiments, during the reaction with the guiding agent and the initiator, ultrasonic oscillation is carried out. The frequency of the ultrasonic oscillation is 15 kHz - 30 kHz, such as 15 kHz, 20 kHz, 25 kHz, 30 kHz, etc. Carrying out ultrasonic oscillation during the reaction with the guiding agent and the initiator, on the one hand, loosens the grains inside the secondary particles and adjusts the sorting of the primary particles; on the other hand, increases the exposed area of the (010) crystal plane and increases the orderly arranged and controllable-sized primary particles.

[0103] In some embodiments, the pH value of the precursor intermediate is adjusted to 8 - 9 with an acid solution, such as 8.0, 8.3, 8.5, 8.7, 9.0, etc. The acid solution is selected from at least one of sulfuric acid solution, acetic acid solution, and citric acid solution, and the acid solution can be any one or several of the above.

[0104] In some embodiments, after the reaction with the initiator is completed, the pH value is raised to 11.0 - 11.5 (such as 11.0, 11.1, 11.2, 11.3, 11.4, 11.5, etc.) with sodium hydroxide solution, and a nickel-cobalt-manganese mixed salt solution, a precipitant solution, and a complexing agent solution are introduced for coprecipitation reaction for 6 h - 20 h (such as 6 h, 8 h, 10 h, 13 h, 15 h, 18 h, 20 h, etc.). Then, after solid-liquid separation, washing, and drying, the precursor is obtained. The method of solid-liquid separation is not limited and can be filtration, etc.; washing can be carried out by water washing, and the number of water washing times is not limited.

[0105] S3. Calcination

[0106] The precursor is mixed with a lithium source and calcined to obtain a ternary cathode material.

[0107] To improve the electrochemical performance of the ternary cathode material, the calcination process is optimized: after the precursor is mixed with the lithium source, it is calcined in two steps to obtain an intermediate of the ternary cathode material; then, the intermediate of the ternary cathode material is mixed with a coating agent and calcined.

[0108] In some embodiments, the two-step calcination includes: first, maintaining the temperature at 400°C - 550°C for 3h - 5h, and then heating up to 750°C - 800°C and maintaining the temperature for 12h - 15h. The heating rate of the two-step calcination can be 2°C / min - 4°C / min. Specifically, the calcination temperature of the first step can be 400°C, 450°C, 500°C, 550°C, etc., and the holding time can be 3h, 4h, 5h, etc.; the calcination temperature of the second step can be 750°C, 760°C, 770°C, 780°C, 790°C, 800°C, etc., and the holding time can be 12h, 13h, 14h, 15h, etc. The atmosphere for calcination can be air or oxygen.

[0109] Further, during feeding, the molar ratio of lithium to the total amount of nickel, cobalt, and manganese is controlled to be (1.03 - 1.07):1, such as 1.03:1, 1.04:1, 1.05:1, 1.06:1, 1.07:1, etc. The precursor and lithium source that meet the ratio requirements are mixed and ground, and then the two-step calcination is carried out to improve the uniformity of the cathode material product. The lithium source is selected from at least one of lithium hydroxide, lithium carbonate, and lithium oxalate, and the lithium source can be any one or several of the above.

[0110] In some embodiments, the coating agent is selected from at least one of V2O5, Al2O3, ZrO2, TiO2, SnO2, ZnO, MgO, RuO2, La2O3, CeO2, Co3O4, SiO2, FePO4, Li3PO4, Li2MnO3, LiAlO2, Li2TiO3, Li2ZrO3, Li3VO4, Li2SiO3, AlF3, LaF3, and MgF2, and the coating agent can be any one or several of the above. By performing surface coating on the cathode material and introducing the above doping elements, it is beneficial to improve the cycle stability of the cathode material. The mass ratio of the coating agent to the ternary cathode material intermediate is (5 - 10):100, such as 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, etc.

[0111] Further, the calcination temperature of the ternary cathode material intermediate and the coating agent is 550°C - 650°C, such as 550°C, 580°C, 600°C, 630°C, 650°C, etc.; the calcination time is 3h - 8h, such as 3h, 4h, 5h, 6h, 7h, 8h, etc.

[0112] The embodiment of the present invention also provides a lithium battery, including the ternary cathode material provided by the embodiment of the present invention. Since the ternary cathode material with the F value within the specified range has better structural stability, it is beneficial to improve the cycle stability of the lithium battery.

[0113] The features and properties of the present invention will be further described in detail below in conjunction with embodiments.

[0114] The embodiments of the present invention provide a ternary cathode material as shown in Table 1. The ternary cathode materials in the examples and comparative examples in Table 1 are tested, and the specific items and methods are as follows:

[0115] (1) Particle size distribution: According to GB / T 19077-2016, a laser particle size analyzer is used to test the particle size distribution information of the ternary cathode materials provided in each example and comparative example.

[0116] (2) Morphology characterization: A scanning electron microscope is used to test the cross-section of the ternary cathode materials provided in each example and comparative example. Figure 1 FIG. is a SEM image of the cross-section of the ternary cathode material provided for Example 1. Figure 2 FIG. is a SEM image of the cross-section of the ternary cathode material provided for Comparative Example 1. Figure 1 In which, the primary particles are arranged more orderly.

[0117] (3) Test method for the angle between the direction of the primary particle deviating from the minimum circumscribed circle radius of the secondary particle (the specific process refers to Figure 3 ): 1) Obtain a SEM image of the cross-section of the analyzable ternary cathode material; 2) Through the tool in ImageJ, find the maximum Feret diameter of the cross-section of the secondary particle, and observe the point C on the cross-section of the secondary particle with the largest distance perpendicular to the Feret diameter. The two ends of the Feret diameter are points A and B respectively. Draw a circle with points A, B, and C to obtain the minimum circumscribed circle corresponding to the cross-section of the secondary particle of the ternary cathode material, and obtain the center of the corresponding minimum circumscribed circle; 3) Identify the boundaries of the primary particles in the SEM image through the tool in ImageJ, and independently select the regions of each primary particle in the SEM image; 4) Through ImageJ analysis, obtain the maximum Feret diameter of each primary particle region, the diameter of the minimum circumscribed circle of the secondary particle, and the included angle between the radial radius of the minimum circumscribed circle of the secondary particle passing through the midpoint of the maximum Feret diameter of the cross-section of the primary particle in the section and the maximum Feret diameter in the direction with the shorter distance from the primary particle to the minimum circumscribed circle. .

[0118] (4) Tap density test: According to GB / T 24533-2009, a tap density tester is used to test the ternary cathode materials provided in each example and comparative example. The test results of each example and comparative example are shown in Table 1.

[0119] (5) True density test: According to GB / T 24586-2009, a Belsorp physical adsorption instrument-TD is used to test the ternary cathode materials provided in each example and comparative example. The test results of each example and comparative example are shown in Table 1.

[0120] (6) Electrochemical performance test:

[0121] Battery Preparation Method: Weigh the prepared cathode material, acetylene black, and PVDF according to a mass ratio of 90:5:5. Add the above three substances to NMP solvent and stir well to mix. After ultrasonic dispersion, make a slurry. Coat the slurry evenly on aluminum foil, then transfer it to a vacuum oven at 120 °C for drying. After 12 h, take out the dried electrode sheet and roll press it, and then punch holes to obtain a circular cathode sheet with a diameter of 14 mm; use a lithium metal sheet as the anode, use a 1 mol·L -1 LiPF6 organic solution (EC:DEC:DMC = 1:1:1, volume ratio) as the electrolyte, use Celgard 2400 polypropylene microporous membrane as the separator, and assemble a button battery in a glove box protected by high-purity argon. After the battery assembly is completed, let it stand for 4 h, and then use a LAND battery test system to conduct electrical performance tests.

[0122] Electrochemical Performance Test: Make button batteries with the cathode materials provided in the examples and comparative examples respectively, and test the discharge specific capacity at 0.1C, 1C, 2C, and 5C at 25 °C; test the capacity retention rate after 100 cycles and 300 cycles at room temperature. The test conditions for the cycling performance are: use a LAND charge and discharge instrument, the voltage range is 3.0 - 4.3V (622\523) and 2.8 - 4.30V (811), and the results are shown in Table 2.

[0123] It should be noted that 50 primary particles are selected, and the selection of 50 primary particles needs to meet the following conditions: <0.1 and 0.1 ≤ ,and the number of selected <0.1 primary particles is 2.5 - 3.5 times the corresponding number of primary particles of 0.1 ≤ The mean value of the parameters is also calculated from 50 particles.

[0124] The mean value of the parameters is also calculated from 50 particles.

[0125] Table 1 Parameters of the ternary cathode materials provided in each example and comparative example

[0126]

[0127] Table 2 Electrochemical performance of the ternary cathode materials provided in each example and comparative example

[0128]

[0129] From the different particle size ratios of primary particles to corresponding secondary particles and different offset angles of primary particles, different values are obtained; from different true densities (ρ) and tap densities (CD), different porosity (ε) values are obtained; further, different 、size particle size distributions By varying the true density (ρ) and the tap density (CD), different porosity (ε) values are obtained, which reflect the overall porosity of the cathode material. If the porosity is too low, it is not conducive to the stress release during the charging and discharging process of the cathode material due to the shrinkage and expansion of the particles; while if the porosity is too high, it will lead to a low volumetric energy density of the material. Compared with Example 1, the ternary cathode materials provided in Examples 7 - 8 have different porosities, corresponding to different F values, and different rate performance and cycling performance of the cathode materials.

[0130] Among them, the relative size of the primary particles to the corresponding secondary particles, and the angle by which the primary particles deviate from the radius of the minimum circumscribed circle of the secondary particles, reflect the arrangement order of the primary particles stacking to form secondary particles, corresponding to the numerical value that reflects the quality of the arrangement order. Specifically, the smaller the ratio of [specific ratio] is, the smaller the influence of θ on the overall arrangement order of the secondary particles is, the smaller the [specific value] is, the better the arrangement order is. Therefore, the corresponding relationship between the primary particles and secondary particles in the ternary cathode material is represented by the formula and the smaller the numerical value, the higher the arrangement order.

[0131] By varying the true density (ρ) and the tap density (CD), different porosity (ε) values are obtained, which reflect the overall porosity of the cathode material. If the porosity is too low, it is not conducive to the stress release during the charging and discharging process of the cathode material due to the shrinkage and expansion of the particles; while if the porosity is too high, it will lead to a low volumetric energy density of the material. Compared with Example 1, the ternary cathode materials provided in Examples 7 - 8 have different porosities, corresponding to different F values, and different rate performance and cycling performance of the cathode materials.

[0132] The proportion of particles with different particle sizes on both sides of the particle size corresponding to the highest volume distribution in the particle size distribution diagram reflects the proportion of large and small particles in the cathode material, which affects the numerical value of [specific value]. The larger this value is, the higher the proportion of large particles, and the lower the cycling performance of the cathode material; the smaller this value is, the higher the proportion of small particles, and the relatively better the cycling performance of the cathode material. Compared with Example 1, Examples 9 - 10 correspond to different values, corresponding to different F values, and different rate performance and cycling performance of the cathode materials.

[0133] The preparation methods of the above examples and comparative examples are described below.

[0134] Example 1

[0135] (1) Prepare the precursor intermediate:

[0136] Nickel sulfate, cobalt sulfate, and manganese sulfate are mixed in water at a molar ratio of 8:1:1 to obtain a metal salt solution, which is added to the bottom solution at a certain rate. A NaOH solution with a concentration of 10 mol / L is added at a certain rate to maintain the pH value of the solution in the reaction kettle at 11.3. At the same time, nitrogen is introduced, and an NH₃·H₂O solution with a concentration of 2 mol / L is added at a certain rate, and the reaction is stirred for 2.5 h to obtain a precursor intermediate, and then the feeding is stopped. Among them, the concentration of the metal salt solution is 2 mol / L, and the feeding rate is 30 mL / min; the temperature during the reaction process is 55 °C, and the stirring rate is 500 rpm; the concentration of the NH₃·H₂O solution in the reaction kettle is 0.9 mol / L. The bottom solution is obtained by mixing a sodium hydroxide solution, an NH₃·H₂O solution, and water. The pH value of the bottom solution is 11.3, and the ammonia concentration of the bottom solution is 0.1 mol / L (i.e., the concentration of ammonia).

[0137] (2)Preparation of precursor:

[0138] After adding a sulfuric acid solution to adjust the pH of the solution in the reaction kettle to 8.5, ultrasonic oscillation is used and allyl ammonium phosphate is added. After the temperature is reduced to 25 °C, the reaction is carried out for 2 h. 2,2-Azobis(2-methylpropylimid) dihydrochloride is added, and the reaction is continued at 25 °C for 2 h. Then the temperature is raised to the original reaction temperature in step (1), a NaOH solution is added to maintain the pH value of the solution in the reaction kettle at 11.3, and the metal salt solution and the NH₃·H₂O solution are continuously added, and the reaction is continued for 15 h. After filtration, washing, and drying, a precursor is obtained. Among them, the concentration of allyl ammonium phosphate in the solution in the reaction kettle is 0.85 mol / L; the concentration of 2,2-azobis(2-methylpropylimid) dihydrochloride in the solution in the reaction kettle is 5 g / L; the frequency of ultrasonic oscillation is 25 kHz.

[0139] (3)Preparation of ternary cathode material:

[0140] The precursor and lithium carbonate are mixed at a molar ratio of Li:(Ni + Co + Mn) of 1.05:1, and then ground and calcined in two steps. Among them, the calcination atmosphere is oxygen. The two-step calcination includes heating to 480 °C in one-step calcination process, holding for 4 h, and then continuing to heat to 750 °C and holding for 15 h to obtain a ternary cathode material intermediate, where the heating rate is 3 °C / min.

[0141] The coating agent TiO₂ and the ternary cathode material intermediate are mixed at a mass ratio of 6:100, and then calcined at 600 °C for 6 h to obtain the ternary cathode material.

[0142] The preparation methods of each example and comparative example are set as follows (the conditions not listed in the following table are the same as those in Example 1):

[0143] (1)Preparation of precursor intermediate:

[0144] Table 3 Parameter settings for preparing precursor intermediates in each example and comparative example

[0145]

[0146] (2) Preparation of precursor:

[0147] Table 4 Parameter settings for preparing precursors in each example and comparative example

[0148]

[0149] (3) Preparation of ternary cathode material:

[0150] Table 5 Parameter settings for preparing ternary cathode materials in each example and comparative example

[0151]

[0152] It can be seen that by introducing a guiding agent and an initiator to react and cooperating with ultrasonic treatment, the value of F can be controlled within the range defined in the present invention, which is beneficial to improving the electrochemical performance of the material. This may be because the above means affect the sorting of crystal grains, can increase the ordered arrangement, and make the size of primary particles more controllable.

[0153] Combined with Tables 1-5, it can be seen that for materials with the same type of nickel-cobalt-manganese molar ratio (such as Examples 1-10), within the specified range, as the value of F increases, its cycling performance gradually decreases.

[0154] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A ternary cathode material, characterized in that, The ternary cathode material satisfies the following: F= ； 0.5°≤F≤40°； wherein, F represents the stability parameter of the ternary cathode material, with the unit of °; Represents the maximum Feret diameter of the primary particle profile corresponding to the primary particles in the secondary particle profile of the ternary cathode material, with the unit of μm; Indicates the minimum circumscribed circle diameter of the secondary particle profile corresponding to the primary particle, with the unit of μm; It represents the included angle between the radial radius of the minimum circumscribed circle of the secondary particle profile passing through the midpoint of the maximum Feret diameter of the primary particle profile in the corresponding profile and the maximum Feret diameter in the direction with a shorter distance from the primary particle to the minimum circumscribed circle, with the unit of °; represents the porosity, , represents the true density, represents the compacted density, and The units are both g / cm 3 ; and respectively represent the particle sizes corresponding to the cumulative volume of the ternary cathode material particles reaching 90% and 10% in the corresponding batches, is the particle size corresponding to the maximum y value in the corresponding particle size distribution diagram, 、 、 The units of are all μm; n represents the number of primary particles selected from the same secondary particle or different secondary particles, and n≥40.

2. The ternary cathode material according to claim 1, characterized in that, The ternary cathode material satisfies at least one of the following characteristics A1-K1: Feature A1: 0.1 ≤ ≤ 1.0; Characteristic B1：0°≤ ≤70°； Feature C1: 0.5° ≤ ≤ 20°; Feature D1: 0.5 ≤ ≤ 20; Characteristic E1：0.1≤ ≤6.5； Feature F1: ≤ 5 μm, 2 μm ≤ ≤ 25 μm, 0.05 ≤ ≤ 0.5; Feature G1: 0° ≤ ≤ 110°; Feature H1: 0.1 ≤ ≤ 0.4; Feature I1: 3μm ≤ ≤ 15μm, 6μm ≤ ≤ 25μm, 2μm ≤ ≤ 8μm; Feature J1: 4.4 g / cm 3 ≤ ≤ 5.1 g / cm 3 , and 3.15 g / cm 3 ≤ ≤ 3.85 g / cm 3 ; Characteristic K1: wherein n The selection of a primary particle needs to meet the following conditions: <0.1 and 0.1 ≤ , and the selected The number of primary particles with <0.1 is 2.5 - 3.5 times the corresponding number of primary particles with 0.1 ≤ of the corresponding number of primary particles.

3. A method for preparing the ternary cathode material according to any one of claims 1-2, characterized in that, including: Performing a coprecipitation reaction using a cobalt source, a nickel source, and a manganese source to obtain a precursor intermediate; The process of preparing the precursor intermediate includes: introducing a nickel-cobalt-manganese mixed salt solution, a precipitant solution, and a complexing agent solution into a reaction kettle with a bottom liquid, and stirring and reacting for 2 h - 3 h; during the process of preparing the precursor intermediate, controlling the stirring rate to be 400 rpm - 700 rpm, the pH value of the solution in the reaction kettle to be 11.0 - 11.5, the complexing agent solution being an ammonia water solution, and adjusting the feeding rate of the ammonia water solution to make the ammonia concentration in the solution in the reaction kettle be 0.7 mol / L - 1.1 mol / L; After adjusting the pH value of the precursor intermediate to 8 - 9, mixing and reacting it with a guiding agent, then mixing and reacting it with an initiator, and then raising the pH value and continuing to perform a coprecipitation reaction using a cobalt source, a nickel source, and a manganese source, followed by solid-liquid separation to obtain a precursor; wherein, the guiding agent is selected from at least one of monoammonium allyl phosphate, vinyl phosphoric acid, cis-propenyl phosphoric acid, and allyl phosphoric acid; the initiator is selected from at least one of 2,2'-azobis(2-methylpropylimid) dihydrochloride and azobisisobutyramidine hydrochloride; during the reaction with the guiding agent and the initiator, ultrasonic oscillation is performed, and the frequency of the ultrasonic oscillation is 15 kHz - 30 kHz; After mixing the precursor with a lithium source, performing two-step calcination to obtain a ternary cathode material intermediate; mixing and calcining the ternary cathode material intermediate with a coating agent; the two-step calcination includes: first maintaining the temperature at 400 °C - 550 °C for 3 h - 5 h, and then raising the temperature to 750 °C - 800 °C and maintaining the temperature for 12 h - 15 h.

4. The preparation method according to claim 3, wherein The process of preparing the precursor using the precursor intermediate satisfies at least one of the following characteristics A2-C2: Characteristic A2: Controlling the addition concentration of the guiding agent to be 0.7 mol / L - 1.0 mol / L; Characteristic B2: The reaction temperature with the guiding agent is 15 °C - 35 °C, and the reaction time is 1.5 h - 2.5 h; Characteristic C2: Adjusting the pH value of the precursor intermediate to 8 - 9 using an acid solution, and the acid solution is selected from at least one of a sulfuric acid solution, an acetic acid solution, and a citric acid solution.

5. The preparation method according to claim 3 or 4, characterized in that, The process of preparing the precursor using the precursor intermediate satisfies at least one of the following characteristics A3-C3: Characteristic A3: Controlling the addition concentration of the initiator to be 4 g / L - 6 g / L; Characteristic B3: The reaction temperature with the initiator is 15 °C - 35 °C, and the reaction time is 1.5 h - 2.5 h; Characteristic C3: After the reaction with the initiator is completed, raising the pH value to 11.0 - 11.5, introducing a nickel-cobalt-manganese mixed salt solution, a precipitant solution, and a complexing agent solution to perform a coprecipitation reaction for 6 h - 20 h, followed by solid-liquid separation, washing, and drying to obtain a precursor.

6. The preparation method according to claim 3, wherein, In the process of preparing the precursor intermediate, the nickel-cobalt-manganese mixed salt solution is obtained by mixing the nickel source, the cobalt source and the manganese source, and the molar ratio of nickel element, cobalt element and manganese element is 5:2:3, 1:1:1, 4:2:4, 6:2:2, 8:1:1 or (86-96):(2-9):(2-5); And / or, in the process of preparing the precursor intermediate, the reaction temperature is controlled to be 45°C - 60°C.

7. The preparation method according to claim 6, characterized in that, The process of preparing the precursor intermediate satisfies at least one of the following characteristics A4 - B4: Characteristic A4: The concentration of the nickel-cobalt-manganese mixed salt solution is 1.5 mol / L - 2.2 mol / L, and the feeding rate is 25 mL / min - 35 mL / min; Characteristic B4: The precipitant solution is a sodium hydroxide solution with a concentration of 10 mol / L - 12 mol / L, and by adjusting the feeding rate of the sodium hydroxide solution, the pH value of the solution in the reaction kettle is maintained at 11.0 - 11.

5.

8. The preparation method according to claim 3, characterized in that, The process of preparing the ternary cathode material using the precursor satisfies at least one of the following characteristics A5 - F5: Characteristic A5: Control the molar ratio of lithium to the total amount of nickel, cobalt and manganese to be (1.03 - 1.07):1; Characteristic B5: Mix and grind the precursor and the lithium source, and then perform two-step calcination; Characteristic C5: The lithium source is selected from at least one of lithium hydroxide, lithium carbonate and lithium oxalate; Characteristic D5: The coating agent is selected from at least one of V2O5, Al2O3, ZrO2, TiO2, SnO2, ZnO, MgO, RuO2, La2O3, CeO2, Co3O4, SiO2, FePO4, Li3PO4, Li2MnO3, LiAlO2, Li2TiO3, Li2ZrO3, Li3VO4, Li2SiO3, AlF3, LaF3 and MgF2; Characteristic E5: The mass ratio of the coating agent to the ternary cathode material intermediate is (5 - 10):100; Characteristic F5: The calcination temperature of the ternary cathode material intermediate and the coating agent is 550°C - 650°C, and the calcination time is 3 h - 8 h.

9. A lithium battery, characterized in that, Including the ternary cathode material described in any one of claims 1 - 2 or the ternary cathode material prepared by the preparation method described in any one of claims 3 - 8.

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