High-nickel ternary positive electrode material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of battery electrodes, and particularly relates to a high-nickel ternary positive electrode material as well as a preparation method and application thereof. The preparation method of the double-rare-earth high-nickel ternary positive electrode material provided by the invention comprises the following steps: 1) mixing a lithium source, a high-nickel ternary precursor and a light rare earth compound, and performing first sintering to obtain a first sintered material; and 2) mixing the primary sintering material obtained in the step 1) with a medium rare earth compound, grinding, and carrying out secondary sintering to obtain the double-rare earth high-nickel ternary positive electrode material. The double-rare-earth high-nickel ternary positive electrode material prepared by the preparation method disclosed by the invention has high first-circle discharge specific capacity, high first-circle efficiency and high cycle capacity retention rate.

Description

Technical Field

[0001] This invention belongs to the field of battery electrode technology, specifically relating to a high-nickel ternary cathode material, its preparation method, and its application. Background Technology

[0002] Ternary lithium-ion batteries have become the mainstay and future of automotive batteries due to their high energy density. High-nickel, low-cobalt ternary cathode materials, with their high theoretical specific capacity, have become one of the main development directions for ternary cathode materials. Although high nickel content can improve energy density and reduce dependence on cobalt resources, its practical application faces failure mechanisms such as bulk structure collapse and interfacial oxygen evolution, which restricts its widespread adoption in the power sector.

[0003] To improve material properties, enhance capacity, and extend cycle life, introducing functional doping and coating materials is an effective approach. Among these, alkaline earth metal doping plays a crucial role, particularly with Mg doping. 2+ For example, it can suppress bulk Li + / Ni 2+ Mixed arrangement stabilizes the crystal structure and optimizes material properties from the inside. Anion doping, on the other hand, focuses on improving surface properties, such as F... - Doping can effectively optimize surface chemical stability. However, this type of doping technology has limitations in improving the overall performance of high-nickel ternary cathode materials and cannot fully meet the requirements for high electrochemical performance, especially in terms of first-cycle discharge specific capacity, first-cycle efficiency, and cycle capacity retention. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the shortcomings of existing high-nickel ternary cathode materials, such as the first-cycle discharge specific capacity, first-cycle efficiency and cycle capacity retention rate, which still need to be improved, thereby providing a high-nickel ternary cathode material, its preparation method and application.

[0005] This invention provides a method for preparing a dual rare-earth high-nickel ternary cathode material, comprising the following steps:

[0006] 1) A lithium source, a high-nickel ternary precursor, and a light rare earth compound are mixed and sintered to obtain a sintered material;

[0007] 2) The sintering material obtained in step 1) is mixed with a medium rare earth compound, ground, and then sintered a second time to obtain the dual rare earth high nickel ternary cathode material.

[0008] Preferably, the light rare earth compound in step 1) is selected from at least one of lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, and samarium oxide;

[0009] The rare earth compound mentioned in step 2) is selected from at least one of europium oxide, gadolinium oxide, and dysprosium oxide.

[0010] Preferably, the chemical formula of the high-nickel ternary precursor in step 1) is: Ni x Co y Mn z (OH)2, where 0.85≤x≤0.95, 0.01≤y≤0.15, 0.01≤z≤0.15 and x+y+z=1.

[0011] Preferably, the ratio of the molar amount of lithium in the lithium source to the total molar amount of metal elements in the high-nickel ternary precursor in step 1) is (1.02-1.08):1;

[0012] And / or, the molar ratio of the light rare earth elements in the light rare earth compound to the total molar ratio of the metal elements in the high-nickel ternary precursor is (0.1-0.5):100.

[0013] Preferably, in step 1), the first sintering temperature is 600-900℃ and the first sintering time is 10-12h;

[0014] In step 1), the atmosphere for the first sintering is selected from an oxygen-containing atmosphere;

[0015] Optionally, after the first sintering step, the process may also include crushing and sieving steps.

[0016] Preferably, the lithium source in step 1) is selected from at least one of lithium carbonate and lithium hydroxide;

[0017] The ratio of the total molar amount of metal elements in the high-nickel ternary precursor described in step 1) to the molar amount of medium rare earth elements in the medium rare earth compound described in step 2) is 100:(0.1-0.8).

[0018] Preferably, in step 2), the second sintering temperature is 300-500℃ and the second sintering time is 3-5h;

[0019] In step 2), the atmosphere for the second sintering is selected from at least one of nitrogen atmosphere, argon atmosphere, and helium atmosphere.

[0020] Preferably, the grinding in step 2) is ball milling;

[0021] The ball milling speed is 300-500 rpm, and the ball milling time is 1-2 hours;

[0022] Optionally, after the second sintering step, a crushing and sieving step may also be included.

[0023] This invention provides a dual rare earth high nickel ternary cathode material, which is prepared by the above-described method for preparing dual rare earth high nickel ternary cathode materials.

[0024] The present invention also provides an application of the above-described dual rare earth high nickel ternary cathode material in lithium-ion batteries.

[0025] The technical solution of this invention has the following advantages:

[0026] 1. The preparation method of the dual rare earth high-nickel ternary cathode material provided by the present invention includes the following steps: 1) mixing a lithium source, a high-nickel ternary precursor, and a light rare earth compound, and performing a first sintering to obtain a sintered material; 2) mixing the sintered material obtained in step 1) with a medium rare earth compound, grinding, and performing a second sintering to obtain the dual rare earth high-nickel ternary cathode material. Rare earth elements have a unique 4f electron layer and an affinity for oxygen. The present invention achieves a gradient design of "light rare earth bulk doping + medium rare earth near-surface doping" through the above-mentioned specific preparation method, breaking through the limitations of traditional single doping. The unique ionic radius and electronic configuration of light rare earths, after being doped into a high-nickel ternary precursor, occupy the Li sites in the bulk phase, thereby optimizing and stabilizing the bulk crystal structure and significantly suppressing structural distortion and particle degradation during cycling. The subsequent doping step of medium rare earths allows the medium rare earths to occupy the transition metal sites of the near-surface doping, improving the near-surface chemical environment, regulating surface activity, effectively blocking side reactions, and enhancing interfacial ion transport. By employing a gradient doping approach combining light rare-earth bulk doping and medium rare-earth near-surface doping, the structural and surface chemical stability of high-nickel ternary cathode materials is effectively improved. This overcomes the limitations and uneven distribution of traditional single-doping elements, avoiding inconsistent local electrochemical performance and crystal structure deterioration, thus optimizing the electrochemical performance of the material from bulk to surface. The high-nickel ternary cathode material prepared by the method of this invention exhibits high first-cycle discharge specific capacity, high first-cycle efficiency, and high cycle capacity retention.

[0027] 2. The preparation method of the dual rare earth high-nickel ternary cathode material provided by the present invention, wherein the light rare earth compound in step 1) is selected from at least one of lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, and samarium oxide; and the medium rare earth compound in step 2) is selected from at least one of europium oxide, gadolinium oxide, and dysprosium oxide. The present invention optimizes the synergistic effect of gradient doping ("light rare earth bulk doping + medium rare earth near-surface doping") by selecting the optimal types of light and medium rare earth compounds, thereby further improving the first-cycle discharge specific capacity, first-cycle efficiency, and cycle capacity retention of the prepared dual rare earth high-nickel ternary cathode material.

[0028] 3. The preparation method of the dual rare-earth high-nickel ternary cathode material provided by the present invention, wherein in step 1), the first sintering temperature is 600-900℃ and the first sintering time is 10-12h; the atmosphere for the first sintering in step 1) is selected from an oxygen-containing atmosphere; in step 2), the second sintering temperature is 300-500℃ and the second sintering time is 3-5h; the atmosphere for the second sintering in step 2) is selected from at least one of a nitrogen atmosphere, an argon atmosphere, and a helium atmosphere. The first sintering temperature of the present invention is relatively high, and the oxygen-containing atmosphere can effectively prevent lattice oxygen loss and lithium source decomposition. The second sintering in a nitrogen atmosphere can create a low-oxygen atmosphere, allowing near-surface lattice oxygen to overflow and providing a channel for the rapid doping of medium rare-earth elements into the surface. The obtained dual rare-earth high-nickel ternary cathode material has higher first-cycle discharge specific capacity, first-cycle efficiency, and cycle capacity retention.

[0029] 4. The preparation method of dual rare earth high nickel ternary cathode material provided by the present invention is a dry process with low energy consumption, is compatible with existing ternary cathode material production lines, and has low equipment investment costs. Detailed Implementation

[0030] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0031] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0032] The high-nickel ternary precursor of the present invention can be prepared by conventional techniques in the art. The Ni used in the examples and comparative examples is as follows. 0.90 Co 0.05 Mn 0.05 The preparation method of the (OH)₂ ternary precursor includes the following steps: 0.90 mol nickel sulfate, 0.05 mol cobalt sulfate, 0.05 mol manganese sulfate, and deionized water are mixed to form a mixed solution, which is then placed in a reaction vessel. The total molar concentration of nickel sulfate, cobalt sulfate, and manganese sulfate in the mixed solution is 4 mol / L. Then, 4 mol / L NaOH solution and 8 mol / L ammonia solution are added to control the pH of the reaction solution to 11.8 and the mass concentration of ammonia in the reaction solution to 8 g / L. A co-precipitation reaction is carried out at 70℃ with continuous stirring at 600 rpm for 50 h. Solid-liquid separation is performed, and the collected solid is washed and dried to obtain the nickel-cobalt-manganese ternary precursor Ni. 0.90 Co 0.05 Mn0.05 (OH)2. Ni used in the examples and comparative examples 0.90 Co 0.04 Mn 0.06 The preparation method of the (OH)₂ ternary precursor includes the following steps: 0.90 mol nickel sulfate, 0.04 mol cobalt sulfate, 0.06 mol manganese sulfate, and deionized water are mixed to form a mixed solution, which is then placed in a reaction vessel. The total molar concentration of nickel sulfate, cobalt sulfate, and manganese sulfate in the mixed solution is 4 mol / L. Then, 4 mol / L NaOH solution and 8 mol / L ammonia solution are added to control the pH of the reaction solution to 11.8 and the mass concentration of ammonia in the reaction solution to 8 g / L. A co-precipitation reaction is carried out at 70℃ with continuous stirring at 600 rpm for 50 h. Solid-liquid separation is performed, and the collected solid is washed and dried to obtain the nickel-cobalt-manganese ternary precursor Ni. 0.90 Co 0.05 Mn 0.05 (OH)2.

[0033] Example 1

[0034] This embodiment provides a method for preparing a dual rare-earth high-nickel ternary cathode material, including the following steps:

[0035] 1) Mix 3.17g lanthanum oxide, 167g lithium hydroxide, and 600g Ni 0.90 Co 0.05 Mn 0.05 The (OH)2 ternary precursor was mixed and sintered at 850°C for 12 hours in an oxygen atmosphere. After that, it was crushed and sieved to obtain a sintered material.

[0036] 2) Mix 2.82g of dysprosium oxide with the sintering material obtained in step 1), mill it in a planetary mill at 300rpm for 2 hours, and then place it in a muffle furnace and sinter it at 380℃ for 4 hours under a nitrogen atmosphere. After that, crush and sieve to obtain the dual rare earth high nickel ternary cathode material.

[0037] Example 2

[0038] This embodiment provides a method for preparing a dual rare-earth high-nickel ternary cathode material, including the following steps:

[0039] 1) Mix 4.26g cerium oxide, 167g lithium hydroxide, and 600g Ni 0.90 Co 0.04 Mn 0.06 The (OH)2 ternary precursor was mixed and sintered at 860°C for 11 hours in an oxygen atmosphere. After that, it was crushed and sieved to obtain a sintered material.

[0040] 2) Mix 3.53g of gadolinium oxide with the sintering material obtained in step 1), mill it in a planetary mill at 400rpm for 1.5h, and then place it in a muffle furnace and sinter it at 380℃ for 4h under a nitrogen atmosphere. After that, crush and sieve to obtain the dual rare earth high nickel ternary cathode material.

[0041] Example 3

[0042] This embodiment provides a method for preparing a dual rare-earth high-nickel ternary cathode material, including the following steps:

[0043] 1) Mix 5.46g neodymium oxide, 167g lithium hydroxide, and 600g Ni 0.90 Co 0.04 Mn 0.06 The (OH)2 ternary precursor was mixed and sintered at 830°C for 12 hours in an oxygen atmosphere. After that, it was crushed and sieved to obtain a sintered material.

[0044] 2) Mix 3.76g of dysprosium oxide with the sintering material obtained in step 1), ball mill at 500rpm for 1h, then place in a muffle furnace and sinter at 390℃ for 4h under a nitrogen atmosphere. After that, crush and sieve to obtain the dual rare earth high nickel ternary cathode material.

[0045] Example 4

[0046] This embodiment provides a method for preparing a dual rare-earth high-nickel ternary cathode material, including the following steps:

[0047] 1) Mix 5.66g of samarium oxide, 167g of lithium hydroxide, and 600g of Ni. 0.90 Co 0.04 Mn 0.06 The ternary precursor (OH)2 was mixed and sintered at 860°C for 12 hours in an oxygen atmosphere. After that, it was crushed and sieved to obtain a sintered material.

[0048] 2) Mix 3.65g of gadolinium oxide with the sintering material obtained in step 1), mill it in a planetary mill at 300rpm for 2 hours, and then place it in a muffle furnace and sinter it at 390℃ for 4 hours under a nitrogen atmosphere. After that, crush and sieve to obtain the dual rare earth high nickel ternary cathode material.

[0049] Comparative Example 1

[0050] This comparative example provides a method for preparing a dual rare-earth high-nickel ternary cathode material, including the following steps:

[0051] 3.17g lanthanum oxide, 2.82g dysprosium oxide, 167g lithium hydroxide, and 600g Ni 0.90 Co 0.05 Mn 0.05The (OH)2 ternary precursor was mixed and sintered at 850°C for 12 hours in an oxygen atmosphere. After that, it was crushed and sieved to obtain the dual rare earth high nickel ternary cathode material.

[0052] Comparative Example 2

[0053] This comparative example provides a method for preparing a dual rare-earth high-nickel ternary cathode material, including the following steps:

[0054] 5.66g samarium oxide, 3.65g gadolinium oxide, 167g lithium hydroxide, and 600g Ni 0.90 Co 0.04 Mn 0.06 The (OH)2 ternary precursor was mixed and sintered at 850°C for 12 hours in an oxygen atmosphere (oxygen partial pressure 95%). After that, it was crushed and sieved to obtain the dual rare earth high nickel ternary cathode material.

[0055] Comparative Example 3

[0056] This comparative example provides a method for preparing a dual rare-earth high-nickel ternary cathode material, including the following steps:

[0057] 1) Mix 2.82g of dysprosium oxide, 167g of lithium hydroxide, and 600g of Ni. 0.90 Co 0.05 Mn 0.05 The (OH)2 ternary precursor was mixed and sintered at 850°C for 12 hours in an oxygen atmosphere. After that, it was crushed and sieved to obtain a sintered material.

[0058] 2) Mix 3.17g of lanthanum oxide with the sintering material obtained in step 1), mill it in a planetary mill at 300rpm for 2h, and then place it in a muffle furnace and sinter it at 380℃ for 4h under a nitrogen atmosphere. After that, crush and sieve to obtain the dual rare earth high nickel ternary cathode material.

[0059] Comparative Example 4

[0060] This comparative example provides a method for preparing a high-nickel ternary cathode material, including the following steps:

[0061] 1) Mix 3.17g lanthanum oxide, 167g lithium hydroxide, and 600g Ni 0.90 Co 0.05 Mn 0.05 The (OH)2 ternary precursor was mixed and sintered at 850°C for 12 hours in an oxygen atmosphere. After that, it was crushed and sieved to obtain a sintered material.

[0062] 2) The sintering material obtained in step 1) is ground in a planetary mill at 300 rpm for 2 hours, and then placed in a muffle furnace and sintered at 380°C for 4 hours in a nitrogen atmosphere. After that, it is crushed and sieved to obtain the dual rare earth high nickel ternary cathode material.

[0063] Compared to Example 1, only the bulk phase is doped with light rare earth compounds.

[0064] Comparative Example 5

[0065] This comparative example provides a method for preparing a high-nickel ternary cathode material, including the following steps:

[0066] 1) Mix 167g lithium hydroxide and 600g Ni 0.90 Co 0.05 Mn 0.05 The (OH)2 ternary precursor was mixed and sintered at 850°C for 12 hours in an oxygen atmosphere. After that, it was crushed and sieved to obtain a sintered material.

[0067] 2) Mix 2.82g of dysprosium oxide with the sintering material obtained in step 1), mill it in a planetary mill at 300rpm for 2 hours, and then place it in a muffle furnace and sinter it at 380℃ for 4 hours under a nitrogen atmosphere. After that, crush and sieve to obtain the dual rare earth high nickel ternary cathode material.

[0068] Test case

[0069] The high-nickel ternary cathode materials obtained in Examples 1-4 and Comparative Examples 1-5 were used as the main materials to prepare lithium-ion batteries (CR2032 type button half-cells), and their electrical performance was tested. Preparation of the button half-cells: The main material, polyvinylidene fluoride (PVDF), and acetylene black were mixed in an N-methylpyrrolidone solvent at a mass ratio of 90 (main material): 5 (PVDF): 5 (acetylene black). The mixture was homogenized, coated, dried, and cut to form the cathode sheet (the areal density of the cathode material was 8.0 mg / cm³). 2 A CR2032 button cell was constructed using a lithium metal sheet as the counter electrode and a Celgard 2500 type separator as the separator. The electrolyte consisted of lithium hexafluorophosphate as the solute and a solution of ethyl methyl carbonate (EMC), ethylene carbonate (EC), and dimethyl carbonate (DMC) in a volume ratio of 1:1:1. The molar concentration of lithium hexafluorophosphate in the electrolyte was 1 mol / L. The cells were assembled in an argon-filled glove box in the following order: negative electrode, electrolyte, separator, electrolyte, and positive electrode.

[0070] The button half-cells prepared above were placed in the Blue Electric testing system for electrical performance testing. The test conditions were as follows: charge / discharge voltage range 2.5V-4.25V; at 25℃, charging at a rate of 0.2C to 4.25V, then discharging at a rate of 0.2C to 2.8V, constituting one cycle. The charge / discharge specific capacity of this cycle was recorded as the initial charge / discharge specific capacity, and the initial efficiency was calculated as (initial discharge specific capacity / initial charge specific capacity * 100%). After two cycles, charging at 0.5C and discharging at 1C for 50 cycles was performed. The charge / discharge specific capacity of the third cycle and the fifth / fifth cycle were recorded. The cycle retention rate was calculated as the ratio of the discharge specific capacity of the fifth / third cycle to 100%. The test results are shown in Table 1.

[0071] Table 1

[0072]

[0073] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a dual rare-earth high-nickel ternary cathode material, characterized in that, Includes the following steps: 1) A lithium source, a high-nickel ternary precursor, and a light rare earth compound are mixed and sintered to obtain a sintered material; 2) The sintering material obtained in step 1) is mixed with a medium rare earth compound, ground, and then sintered a second time to obtain the dual rare earth high nickel ternary cathode material.

2. The preparation method of the dual rare earth high-nickel ternary cathode material according to claim 1, characterized in that, The light rare earth compound mentioned in step 1) is selected from at least one of lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, and samarium oxide; The rare earth compound mentioned in step 2) is selected from at least one of europium oxide, gadolinium oxide, and dysprosium oxide.

3. The preparation method of the dual rare-earth high-nickel ternary cathode material according to claim 1 or 2, characterized in that, The general chemical formula of the high-nickel ternary precursor mentioned in step 1) is: Ni x Co y Mn z (OH)2, where 0.85≤x≤0.95, 0.01≤y≤0.15, 0.01≤z≤0.15 and x+y+z=1.

4. The method for preparing the dual rare-earth high-nickel ternary cathode material according to any one of claims 1-3, characterized in that, The ratio of the molar amount of lithium in the lithium source to the total molar amount of metal elements in the high-nickel ternary precursor in step 1) is (1.02-1.08):1; And / or, the molar ratio of the light rare earth elements in the light rare earth compound to the total molar ratio of the metal elements in the high-nickel ternary precursor is (0.1-0.5):

100.

5. The method for preparing the dual rare-earth high-nickel ternary cathode material according to any one of claims 1-4, characterized in that, In step 1), the first sintering temperature is 600-900℃, and the first sintering time is 10-12h; In step 1), the atmosphere for the first sintering is selected from an oxygen-containing atmosphere; Optionally, after the first sintering step, the process may also include crushing and sieving steps.

6. The method for preparing the dual rare-earth high-nickel ternary cathode material according to any one of claims 1-5, characterized in that, The lithium source mentioned in step 1) is selected from at least one of lithium carbonate and lithium hydroxide; The ratio of the total molar amount of metal elements in the high-nickel ternary precursor described in step 1) to the molar amount of medium rare earth elements in the medium rare earth compound described in step 2) is 100:(0.1-0.8).

7. The method for preparing the dual rare-earth high-nickel ternary cathode material according to any one of claims 1-6, characterized in that, In step 2), the second sintering temperature is 300-500℃, and the second sintering time is 3-5h; In step 2), the atmosphere for the second sintering is selected from at least one of nitrogen atmosphere, argon atmosphere, and helium atmosphere.

8. The method for preparing the dual rare-earth high-nickel ternary cathode material according to any one of claims 1-6, characterized in that, The grinding described in step 2) is ball milling; The ball milling speed is 300-500 rpm, and the ball milling time is 1-2 hours; Optionally, after the second sintering step, a crushing and sieving step may also be included.

9. A dual rare-earth high-nickel ternary cathode material, characterized in that, It is prepared by the preparation method of the dual rare earth high nickel ternary cathode material according to any one of claims 1-8.

10. The application of the dual rare earth high nickel ternary cathode material according to claim 9 in lithium-ion batteries.

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