High-nickel ternary positive electrode material, preparation method, positive electrode sheet, secondary battery and application

Abstract

The application relates to a high-nickel ternary positive electrode material, a preparation method, a positive electrode sheet, a secondary battery and application, and belongs to the technical field of lithium ion secondary batteries. The high-nickel ternary positive electrode material comprises a material with a chemical formula of LiNi x Co y Mn z X a Y b O2, wherein 0.8<=x<0.96, y>0, z>0, 0.001<=a<=0.05, 0.001<=b<=0.05, x+y+z+a=1, X and Y are doping elements, X comprises one or more of Al and In, and Y comprises one or more of B and Si. The high-nickel ternary positive electrode material can improve the cycle performance and thermal stability by doping X elements and Y elements.

Description

Technical Field

[0001] This application relates to the field of lithium-ion secondary battery technology, and in particular to a high-nickel ternary cathode material, its preparation method, cathode sheet, secondary battery, and its application. Background Technology

[0002] Rechargeable lithium-ion batteries (LIBs), as high-performance electrochemical energy storage devices, are increasingly widely used in consumer electronics, the automotive industry, and grid energy storage, becoming one of the solutions for achieving efficient energy conversion and storage. Since cathode materials dominate the weight and cost of LIBs, developing cathode materials with excellent comprehensive performance, including high capacity, long cycle life, high power, and high safety, is of great significance for the development of next-generation LIBs.

[0003] Among various cathode material systems, LiNi is a high-nickel ternary cathode material with a layered structure. x Co y Mn 1-x-y O2 (x≥0.8, x+y<1) has a high reversible specific capacity (over 200mAh g). -1 ) and higher operating voltage (3.8V vs. Li / Li) + With its advantages such as high energy content, it has been successfully used in electric vehicles with a single-charge driving range of over 500 kilometers. While increasing the nickel content in traditional high-nickel ternary cathode materials can significantly increase capacity, it faces the problem of gradually deteriorating cycle performance and thermal stability. Summary of the Invention

[0004] Therefore, it is necessary to provide a high-nickel ternary cathode material, a preparation method, a cathode sheet, a secondary battery, and an application to improve the cycle performance and thermal stability of the high-nickel ternary cathode material.

[0005] The first aspect of this application provides a high-nickel ternary cathode material, including a material with the chemical formula LiNi. x Co y Mn z X a Y b The material is O2, wherein 0.8≤x<0.96, y>0, z>0, 0.001≤a≤0.05, 0.001≤b≤0.05, x+y+z+a=1, and X and Y are doping elements, wherein X includes one or more of Al and In, and Y includes one or more of B and Si.

[0006] In some embodiments, the dopant element X is distributed in the chemical formula LiNi x Co y Mn z X aY b In the bulk lattice of the O2 material, the dopant element Y is enriched in the LiNi material. x Co y Mn z X a Y b The surface of the material containing O2.

[0007] In some embodiments, the specific surface area of ​​the high-nickel ternary cathode material is 0.4 m². 2 / g~0.7m 2 / g.

[0008] In some embodiments, the mass percentage of Li2CO3 in the high-nickel ternary cathode material is 0.05wt% to 0.15wt%.

[0009] In some embodiments, the mass percentage of LiOH in the high-nickel ternary cathode material is 0.30wt% to 0.40wt%.

[0010] The second aspect of this application provides a method for preparing the high-nickel ternary cathode material described in the first aspect of this application, comprising the following steps:

[0011] An additive, a lithium source, and a precursor containing nickel, cobalt, and manganese are mixed to obtain a mixture, wherein the additive contains dopant element X and dopant element Y.

[0012] The mixture is then subjected to sintering treatment.

[0013] In some embodiments, the precursor containing nickel, cobalt, and manganese comprises a precursor with the chemical formula Ni. m Co n Mn 1-m-n The material is (OH)2, where 0.8 ≤ m < 0.96, n > 0, and m + n < 1;

[0014] Optionally, the additive includes one or more of the following: oxides, carbonates, hydroxides, and acetates of dopant element X and dopant element Y;

[0015] Optionally, the lithium source includes one or more of lithium hydroxide, lithium carbonate, lithium acetate, and lithium nitrate.

[0016] In some embodiments, the molar ratio of lithium in the lithium source to the precursor containing nickel, cobalt and manganese is (1.01~1.06):1.

[0017] In some embodiments, the amount of dopant element X in the mixture is 0.1% to 0.6% of the total amount of the additive, the lithium source, and the precursor containing nickel, cobalt, and manganese.

[0018] The amount of dopant element Y in the mixture is 0.4% to 1% of the total amount of the additive, the lithium source and the precursor containing nickel, cobalt and manganese.

[0019] In some embodiments, the sintering process includes the following steps: placing the mixture in an oxygen-containing sintering atmosphere and sintering at 450°C to 600°C for 2 to 10 hours, and then sintering at 650°C to 900°C for 10 to 20 hours.

[0020] Optionally, the volume percentage of oxygen in the oxygen-containing sintering atmosphere is ≥97%.

[0021] A third aspect of this application provides a cathode material comprising the high-nickel ternary cathode material described in the first aspect of this application or the high-nickel ternary cathode material prepared by the preparation method described in the second aspect of this application.

[0022] A fourth aspect of this application provides a secondary battery including the positive electrode sheet described in the third aspect of this application.

[0023] The fifth aspect of this application provides an electrical device including the secondary battery described in the fourth aspect of this application.

[0024] Compared with traditional technologies, the above-mentioned high-nickel ternary cathode materials, preparation methods, cathode sheets, secondary batteries, and applications have at least the following advantages:

[0025] (1) The X and Y elements doped in the above-mentioned high-nickel ternary cathode material can enhance the interionic interaction force and bond energy of the cathode material while suppressing surface reconstruction during the cycling process. They can also take into account the dual functionality of doping and surface coating, thereby synergistically improving the crystal structure stability and surface chemical stability of the high-nickel ternary cathode material, thus improving its cycling performance and thermal stability.

[0026] (2) The competitive doping strategy of simultaneously doping X and Y elements in the above high-nickel ternary cathode material can achieve the substitution of X elements and the filling of lattice gaps without reducing its specific capacity. This avoids the lattice distortion and the obstruction of bulk diffusion caused by Y elements with smaller ionic radii being doped into the interstitial positions. Attached Figure Description

[0027] Figure 1 This is a SEM image of the high-nickel ternary cathode material prepared in Example 1 of this application.

[0028] Figure 2 This is a SEM image of the high-nickel ternary cathode material prepared in Comparative Example 1 of this application.

[0029] Figure 3 The image shows the XRD pattern of the high-nickel ternary cathode material prepared in Example 1 of this application.

[0030] Figure 4 This is a comparison chart of the cycle performance of the high-nickel ternary cathode materials prepared in Example 1 and Comparative Example 1 of this application. Detailed Implementation

[0031] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0032] In this application, unless otherwise defined, all technical terms and jargon not explicitly stated have the same meaning as commonly understood by those skilled in the art and are common knowledge to those skilled in the art. Methods not explicitly stated are all conventional methods known to those skilled in the art. The term "multiple" in this application means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0033] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0034] One embodiment of this application provides a high-nickel ternary cathode material, including materials with the chemical formula LiNi. x Co y Mn z X a Y b The material is O2, wherein 0.8≤x<0.96, y>0, z>0, 0.001≤a≤0.05, 0.001≤b≤0.05, x+y+z+a=1, and X and Y are doping elements, wherein X includes one or more of Al and In, and Y includes one or more of B and Si.

[0035] The high-nickel ternary cathode material described in this application co-dops X and Y elements into the matrix of the high-nickel ternary cathode material (i.e., the undoped high-nickel ternary cathode material). By utilizing the differences in the coordination space configurations and migration barriers of the two elements X and Y to form competitive doping, X element substitution and lattice void filling, as well as Y element enrichment on the matrix surface, can be achieved in one step. This can enhance the interionic forces and bond energies of the high-nickel ternary cathode material while suppressing surface reconstruction during cycling. Furthermore, it takes into account the dual functionality of doping and surface coating, thereby synergistically improving the crystal structure stability and surface chemical stability of the high-nickel ternary cathode material, thus improving its cycling performance and thermal stability. This overcomes the capacity decay problems caused by lattice collapse and surface reconstruction during cycling of traditional high-nickel ternary cathode materials.

[0036] While traditional element doping techniques can improve the stability of high-nickel ternary cathode materials to some extent, they also occupy lithium intercalation sites in the bulk lattice while stabilizing the bulk lattice structure of the high-nickel ternary cathode material, resulting in a partial loss of specific capacity of the high-nickel ternary cathode material.

[0037] The competitive doping strategy described in this application can achieve X element substitution and lattice void filling without reducing the proportion of nickel in the high-nickel ternary cathode material, i.e., without reducing its specific capacity. This avoids the lattice distortion and hindrance to bulk diffusion caused by Y element doping into interstitial positions, which has a smaller ionic radius. Furthermore, since the price of nickel is much lower than that of cobalt, the high-nickel ternary cathode material has a high proportion of nickel and a low proportion of transition metals such as cobalt, thus taking advantage of low raw material costs. It is understandable that x can be, for example, 0.8, 0.82, 0.85, 0.87, 0.9, 0.92, or 0.95, etc.; a can be, for example, 0.001, 0.003, 0.005, 0.008, 0.01, 0.02, 0.03, 0.04, or 0.05, etc.; and b can be, for example, 0.001, 0.003, 0.005, 0.008, 0.01, 0.02, 0.03, 0.04, or 0.05, etc.

[0038] In some embodiments, the dopant element X is distributed in the chemical formula LiNi x Co y Mn z X a Y b In the bulk lattice of the O2 material, the dopant element Y is enriched in the LiNi alloy. x Co y Mn z X a Y b The surface of the material containing O2.

[0039] It should be noted that the doping site and doping depth of an element can significantly affect the overall performance of high-nickel ternary cathode materials. Therefore, the type, doping site, and doping depth of the element are crucial for improving the performance of high-nickel ternary cathode materials. In this application, X and Y were chosen as doping elements because their outer electron configurations and ionic radii are significantly different, allowing them to form different coordination space configurations and exhibiting different diffusion barriers during doping. The migration barrier of element Y in the bulk crystal structure is higher than that of element X, resulting in slower diffusion kinetics. Therefore, during co-doping with element X, the migration barrier of element Y increases significantly, and element Y tends to diffuse more readily in the LiNi0 form. x Co y Mn z X a Y b O2 accumulates on the surface of materials with the chemical formula LiNi, making it easier for X element to enter. x Co y Mn z X a Y b In the transition metal layer of the O2 material. Specifically, since X includes one or more of Al and In, and Y includes one or more of B and Si, the 3s and 3p orbitals of element X can hybridize with d orbitals to form sp... 3 d 2 Hybrid orbitals can bond with lattice oxygen to form XO6 octahedra, and X 3+ The ionic radius of LiNi is close to that of transition metal cations in high-nickel ternary cathode materials, and it has a smaller diffusion barrier, making it easier to dope LiNi. x Co y Mn z X a Y b O2 exists in the transition metal layer of the bulk crystal lattice of a material. Therefore, elements X and Y are present in the chemical formula LiNi. x Co y Mn z X a Y b The different distribution patterns of O2 in the material enable it to enhance the interionic forces and bond energies of high-nickel ternary cathode materials while suppressing surface reconstruction during the cycling process. It also takes into account the dual functionality of doping and surface coating, thereby synergistically improving the crystal structure stability and surface chemical stability of high-nickel ternary cathode materials, thus enhancing their cycle performance and thermal stability.

[0040] In some implementations, 0 < y < 0.198, 0 < z < 0.198. It is understood that y may include, but is not limited to, 0.001, 0.002, 0.005, 0.007, 0.009, 0.01, 0.03, 0.05, 0.08, 0.101, 0.132, 0.156, 0.173, or 0.197; and z may include, but is not limited to, 0.001, 0.003, 0.005, 0.007, 0.009, 0.01, 0.03, 0.05, 0.07, 0.112, 0.135, 0.159, 0.175, or 0.197.

[0041] In some preferred embodiments, z > y. It should be noted that when z > y, the cobalt content in the high-nickel ternary cathode material is relatively low, and the high-nickel ternary cathode material is a high-nickel low-cobalt ternary cathode material. This high-nickel low-cobalt ternary cathode material not only has the advantage of low cost, but also shows more significant improvements in cycle performance and thermal stability.

[0042] In some implementations, the specific surface area of ​​the high-nickel ternary cathode material is 0.4 m². 2 / g~0.7m 2 / g. It is understood that the specific surface area of ​​high-nickel ternary cathode materials can be, but is not limited to, 0.4m². 2 / g, 0.45m 2 / g, 0.5m 2 / g, 0.55m 2 / g, 0.6m 2 / g, 0.65m 2 / g or 0.7m 2 / g etc.

[0043] In some embodiments, the mass percentage of Li2CO3 in the high-nickel ternary cathode material is 0.05wt% to 0.15wt%. It is understood that the mass percentage of Li2CO3 in the high-nickel ternary cathode material can be, for example, 0.05wt%, 0.06wt%, 0.07wt%, 0.08wt%, 0.09wt%, 0.1wt%, 0.11wt%, 0.12wt%, 0.13wt%, 0.14wt%, or 0.15wt%, etc.

[0044] In some embodiments, the mass percentage of LiOH in the high-nickel ternary cathode material is 0.30 wt% to 0.40 wt%. It is understood that the mass percentage of LiOH in the high-nickel ternary cathode material can be, for example, 0.3 wt%, 0.31 wt%, 0.32 wt%, 0.33 wt%, 0.34 wt%, 0.35 wt%, 0.36 wt%, 0.37 wt%, 0.38 wt%, 0.39 wt%, or 0.4 wt%, etc.

[0045] Another embodiment of this application provides a method for preparing the above-mentioned high-nickel ternary cathode material, comprising the following steps:

[0046] Additives, lithium source and precursor containing nickel, cobalt and manganese are mixed to obtain a mixture, the additive contains dopant element X and dopant element Y;

[0047] The mixture is sintered.

[0048] During the sintering process described above, dopant elements X and Y, due to their significant differences in electron configuration and ionic radius, can form different coordination space configurations and exhibit different diffusion barriers during doping. The migration barrier of element Y in the bulk crystal structure is higher than that of element X, resulting in slower diffusion kinetics. Therefore, during co-doping with X and Y, the migration barrier of element Y increases significantly, and element Y tends to diffuse more readily in LiNi0 crystals. x Co y Mn z X a Y b O2 accumulates on the surface of materials with the chemical formula LiNi, making it easier for X element to enter. x Co y Mn z X a Y b In the transition metal layer of the O2 material, through this competitive doping, a layered co-doping effect of uniform doping of the X bulk phase and enrichment of the Y surface can be achieved in one step. This can synergistically improve the crystal structure stability and surface chemical stability of the high-nickel ternary cathode material, thereby improving its cycle performance and thermal stability. This overcomes the capacity decay problems caused by lattice collapse and surface reconstruction during the cycling process of traditional high-nickel ternary cathode materials.

[0049] Furthermore, the aforementioned competitive doping strategy can achieve X element substitution and lattice void filling without reducing the nickel content in the high-nickel ternary cathode material, i.e., without reducing its specific capacity. This avoids the lattice distortion and hindrance to bulk diffusion caused by Y element, which has a smaller ionic radius, doping into interstitial positions. Simultaneously, since the price of nickel is much lower than that of cobalt, the aforementioned high-nickel ternary cathode material has a high nickel content and a low proportion of transition metals such as cobalt, thus taking advantage of low raw material costs. Specifically, the doping element X in this application is distributed in the chemical formula LiNi x Co y Mn z X a Y b In the bulk lattice of the O2 material, the dopant element Y is distributed in the LiNi phase. x Co y Mn z X a Y b The surface of the material containing O2.

[0050] Furthermore, the above preparation method is simple and low-cost, and high-nickel ternary cathode materials can be prepared by one-step sintering. The preparation method of this application has advantages over traditional two-stage or three-stage sintering processes in terms of process and cost.

[0051] In some embodiments, the precursor containing nickel, cobalt, and manganese includes a precursor with the chemical formula Ni. m Co n Mn 1-m-n For (OH)₂ materials, 0.8 ≤ m < 0.96, n > 0, and m + n < 1. It can be understood that m can be 0.8, 0.82, 0.84, 0.86, 0.88, 0.9, 0.92, 0.94, etc., and n can be, for example, 0.04, 0.05, 0.08, 0.1, 0.12, 0.15, or 0.18, etc.

[0052] In some embodiments, the additive includes one or more of the following: oxides, carbonates, hydroxides, and acetates of dopant element X and dopant element Y. It should be noted that the above-mentioned additive contains not only dopant element X but also dopant element Y. The additive may include, but is not limited to, compounds containing both dopant element X and dopant element Y, compounds containing dopant element X but not dopant element Y, and compounds containing dopant element Y but not dopant element X, or any combination thereof. The compound may be an oxide, carbonate, hydroxide, or acetate, but is not limited thereto. For example, the additive may include oxides containing dopant element X and oxides containing dopant element Y, or oxides containing dopant element X and hydroxides containing dopant element Y, or carbonates containing both dopant elements X and Y, etc.

[0053] In some embodiments, the lithium source includes one or more of lithium hydroxide, lithium carbonate, lithium acetate, and lithium nitrate.

[0054] In some embodiments, the molar ratio of lithium in the lithium source to the precursor containing nickel, cobalt, and manganese is (1.01~1.06):1. It is understood that the molar ratio of lithium in the lithium source to the precursor containing nickel, cobalt, and manganese can be, for example, 1.01:1, 1.02:1, 1.04:1, or 1.06:1, etc.

[0055] In some embodiments, the amount of dopant element X in the mixture is 0.1% to 0.6% of the total amount of additives, lithium source, and precursors containing nickel, cobalt, and manganese.

[0056] The amount of element Y doped in the mixture is 0.4% to 1% of the total amount of additives, lithium source and precursors containing nickel, cobalt and manganese.

[0057] It should be noted that the type, amount, doping site, and depth of doping are crucial for improving the performance of high-nickel ternary cathode materials. This application further enhances the cycle stability and thermal stability of the aforementioned high-nickel ternary cathode material by controlling the percentage of doping element X and doping element Y in the mixture. It is understood that the percentage of doping element X in the mixture can be, for example, 0.2%, 0.3%, 0.4%, 0.5%, or 0.6%, and the percentage of doping element Y in the mixture can be, for example, 0.4%, 0.6%, 0.8%, or 1%. For example, when the mixture consists of 0.005 mol Al₂O₃, 0.005 mol B₂O₃, 1.04 mol LiOH·H₂O, and 1 mol Ni… 0.83 Co 0.06 Mn0.11 When (OH)2 is mixed, the amount of dopant element Al accounts for the proportion of Al2O3, B2O3, LiOH·H2O, and Ni. 0.83 Co 0.06 Mn 0.11 The total molar percentage of (OH)2 is 0.488%, and the dopant element B accounts for a certain percentage of Al2O3, B2O3, LiOH·H2O, and Ni. 0.83 Co 0.06 Mn 0.11 The total amount of (OH)2 is 0.488%.

[0058] In some embodiments, the additive, lithium source, and precursor containing nickel, cobalt, and manganese are mixed using a dry airflow mixing method. The airflow mixer operates at a speed of 500 rpm to 1000 rpm, and the mixing time is 20 to 60 minutes. This dry airflow mixing method ensures thorough and uniform mixing of the additive, lithium source, and precursor containing nickel, cobalt, and manganese, which is beneficial for subsequent sintering. It is understood that the airflow mixer speed can be, for example, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, or 1000 rpm, and the mixing time can be, for example, 20 minutes, 30 minutes, 40 minutes, 50 minutes, or 60 minutes.

[0059] In some embodiments, the sintering process includes the following steps: placing the mixture in an oxygen-containing sintering atmosphere and sintering at 450°C to 600°C for 2 to 10 hours, followed by sintering at 650°C to 900°C for 10 to 20 hours. It should be noted that the doping sites and doping depth of the elements are crucial for improving the performance of high-nickel ternary cathode materials. This application can control the doping sites and doping depth of elements X and Y by controlling the sintering process conditions, thereby further improving the cycle stability and thermal stability of the high-nickel ternary cathode material. It is understood that the sintering temperature of 450°C to 600°C can be, for example, 450°C, 500°C, 550°C, or 600°C, etc., and the sintering time of 2 hours to 10 hours can be, for example, 2 hours, 4 hours, 6 hours, 8 hours, or 10 hours, etc. The sintering temperature of 650°C to 900°C can be, for example, 650°C, 700°C, 750°C, 800°C, 850°C, or 900°C, etc. Specifically, the sintering process is carried out in an experimental furnace. After sintering, the resulting high-nickel ternary cathode material is allowed to cool naturally while the experimental furnace remains sealed. The high-nickel ternary cathode material is then removed once the furnace temperature drops below 50°C. More specifically, the obtained high-nickel ternary cathode material can be crushed and sieved before reuse, with the sieve mesh size ranging from 200 to 400 mesh.

[0060] In some embodiments, the volume percentage of oxygen in the oxygen-containing sintering atmosphere is ≥97%. It is understood that the volume percentage of oxygen in the oxygen-containing sintering atmosphere may be, for example, 97%, 97.5%, 98%, 98.5%, or 99%, etc.

[0061] Another embodiment of this application provides a positive electrode sheet, comprising the above-described high-nickel ternary positive electrode material or the high-nickel ternary positive electrode material prepared by the above-described preparation method. The positive electrode sheet comprises a positive current collector and an active material layer, wherein the active material layer is coated on at least one surface of the positive current collector, and the positive electrode material in the active material layer comprises the above-described high-nickel ternary positive electrode material or the high-nickel ternary positive electrode material prepared by the above-described preparation method.

[0062] Another embodiment of this application provides a secondary battery including the aforementioned positive electrode. The secondary battery may include, for example, the aforementioned positive electrode, negative electrode, electrolyte, and separator. The separator is disposed between the positive and negative electrodes, primarily serving to prevent short circuits between the positive and negative electrodes, while simultaneously allowing ions to pass through. The electrolyte serves to conduct ions between the positive and negative electrodes. During the charging and discharging process of the secondary battery, lithium ions repeatedly insert and extract between the positive and negative electrodes. This application does not impose any particular limitations on the negative electrode, electrolyte, and separator; the negative electrode prepared using methods commonly used in this technical field and the electrolyte and separator commonly used in this art can be used.

[0063] Another embodiment of this application provides an electrical device including the aforementioned secondary battery. The aforementioned electrical device may include any device or apparatus powered by a secondary battery, such as mobile phones, laptops, electric vehicles, ships, satellites, energy storage devices, smart home appliances, etc., but is not limited thereto.

[0064] To further illustrate this application, the technical solution of this application will be described in detail below with reference to specific embodiments and comparative examples.

[0065] Example 1

[0066] In this embodiment, Al2O3 and B2O3 are selected as additives, LiOH·H2O is selected as the lithium source, and Ni is selected as the precursor containing nickel, cobalt and manganese. 0.83 Co 0.06 Mn 0.11 (OH)2.

[0067] The preparation method of the high-nickel ternary cathode material in this embodiment includes the following steps:

[0068] (1) Weigh the precursor Ni 0.83 Co 0.06 Mn 0.11(OH)2, LiOH·H2O, Al2O3 and B2O3, in molar ratios, Ni 0.83 Co 0.06 Mn 0.11 (OH)2:LiOH·H2O:Al2O3:B2O3=1:1.04:0.005:0.01. The above four compounds were placed in an air jet mixer and mixed at a speed of 850 rpm / min for 40 min. After thorough mixing, a mixture was obtained.

[0069] (2) The mixture was transferred to an atmosphere furnace for high-temperature sintering in a sintering atmosphere. First, the temperature was increased to 550℃ at a heating rate of 2.5℃ / min and calcined for 5.5h. Then, the temperature was increased to 760℃ at a heating rate of 2.5℃ / min and calcined for 13.5h. The oxygen content in the sintering atmosphere was 99 vol%. The furnace was cooled, and the resulting material was subjected to roller crushing, ultracentrifugal grinding, and 325-mesh sieve treatment to obtain high-nickel ternary cathode material LiNi. 0.83 Co 0.05 Mn 0.11 Al 0.01 B 0.02 O2.

[0070] Example 2

[0071] In this embodiment, Al2O3 and B2O3 are selected as additives, LiOH·H2O is selected as the lithium source, and Ni is selected as the precursor containing nickel, cobalt and manganese. 0.83 Co 0.06 Mn 0.11 (OH)2.

[0072] The preparation method of the high-nickel ternary cathode material in this embodiment includes the following steps:

[0073] (1) Weigh the precursor Ni 0.83 Co 0.06 Mn 0.11 (OH)2, LiOH·H2O, Al2O3 and B2O3, in molar ratios, Ni 0.83 Co 0.06 Mn 0.11 (OH)2:LiOH·H2O:Al2O3:B2O3=1:1.04:0.005:0.005. The above four compounds were placed in an air jet mixer and mixed at a speed of 850 rpm / min for 40 min. After thorough mixing, a mixture was obtained.

[0074] (2) The mixture was transferred to an atmosphere furnace for high-temperature sintering in a sintering atmosphere. First, the temperature was increased to 550℃ at a heating rate of 2.5℃ / min and calcined for 5.5h. Then, the temperature was increased to 760℃ at a heating rate of 2.5℃ / min and calcined for 13.5h. The oxygen content in the sintering atmosphere was 99 vol%. The furnace was cooled, and the resulting material was subjected to roller crushing, ultracentrifugal grinding, and 325-mesh sieve treatment to obtain high-nickel ternary cathode material LiNi. 0.83 Co 0.05 Mn 0.11 Al 0.01 B 0.01 O2.

[0075] Example 3

[0076] In this embodiment, Al(OH)3 and B2O3 are selected as additives, LiOH·H2O is selected as the lithium source, and Ni is selected as the precursor containing nickel, cobalt and manganese. 0.83 Co 0.06 Mn 0.11 (OH)2.

[0077] The preparation method of the high-nickel ternary cathode material in this embodiment includes the following steps:

[0078] (1) Weigh the precursor Ni 0.83 Co 0.06 Mn 0.11 (OH)2, LiOH·H2O, Al(OH)3 and B2O3, in molar ratios, Ni 0.83 Co 0.06 Mn 0.11 (OH)2:LiOH·H2O:Al(OH)3:B2O3=1:1.04:0.01:0.005. The above four compounds were placed in an air jet mixer and mixed at a speed of 850 rpm / min for 40 min. After thorough mixing, a mixture was obtained.

[0079] (2) The mixture was transferred to an atmosphere furnace for high-temperature sintering in a sintering atmosphere. First, the temperature was increased to 550℃ at a heating rate of 2.5℃ / min and calcined for 5.5h. Then, the temperature was increased to 770℃ at a heating rate of 2.5℃ / min and calcined for 13.5h. The oxygen content in the sintering atmosphere was 99 vol%. The furnace was cooled, and the resulting material was subjected to roller crushing, ultracentrifugal grinding, and 325-mesh sieve treatment in sequence to obtain high-nickel ternary cathode material LiNi. 0.83 Co 0.05 Mn 0.11 Al 0.01 B 0.01 O2.

[0080] Example 4

[0081] In this embodiment, Al2O3 and SiO are selected as additives, LiOH·H2O is selected as the lithium source, and Ni is selected as the precursor containing nickel, cobalt and manganese. 0.83 Co 0.06 Mn 0.11 (OH)2.

[0082] The preparation method of the high-nickel ternary cathode material in this embodiment includes the following steps:

[0083] (1) Weigh the precursor Ni 0.83 Co 0.06 Mn 0.11 (OH)2, LiOH·H2O, Al2O3 and SiO, Ni, in molar ratio. 0.83 Co 0.06 Mn 0.11 (OH)2:LiOH·H2O:Al2O3:SiO=1:1.04:0.005:0.01. The above four compounds were placed in an air jet mixer and mixed at a speed of 850 rpm / min for 40 min. After thorough mixing, a mixture was obtained.

[0084] (2) The mixture was transferred to an atmosphere furnace for high-temperature sintering in a sintering atmosphere. First, the temperature was increased to 550℃ at a heating rate of 2.5℃ / min and calcined for 5.5h. Then, the temperature was increased to 770℃ at a heating rate of 2.5℃ / min and calcined for 13.5h. The oxygen content in the sintering atmosphere was 99 vol%. The furnace was cooled, and the resulting material was subjected to roller crushing, ultracentrifugal grinding, and 325-mesh sieve treatment in sequence to obtain high-nickel ternary cathode material LiNi. 0.83 Co 0.05 Mn 0.11 Al 0.01 Si 0.01 O2.

[0085] Example 5

[0086] In this embodiment, In₂O₃ and B₂O₃ are selected as additives, LiOH·H₂O is selected as the lithium source, and Ni is selected as the precursor containing nickel, cobalt, and manganese. 0.83 Co 0.06 Mn 0.11 (OH)2.

[0087] The preparation method of the high-nickel ternary cathode material in this embodiment includes the following steps:

[0088] (1) Weigh the precursor Ni 0.83 Co 0.06 Mn 0.11(OH)2, LiOH·H2O, In2O3 and B2O3, Ni, in molar ratio 0.83 Co 0.06 Mn 0.11 (OH)2:LiOH·H2O:In2O3:B2O3=1:1.04:0.005:0.005. The above four compounds were placed in an air jet mixer and mixed at a speed of 850 rpm / min for 40 min. After thorough mixing, a mixture was obtained.

[0089] (2) The mixture was transferred to an atmosphere furnace for high-temperature sintering in a sintering atmosphere. First, the temperature was increased to 550℃ at a heating rate of 2.5℃ / min and calcined for 5.5h. Then, the temperature was increased to 770℃ at a heating rate of 2.5℃ / min and calcined for 13.5h. The oxygen content in the sintering atmosphere was 99 vol%. The furnace was cooled, and the resulting material was subjected to roller crushing, ultracentrifugal grinding, and 325-mesh sieve treatment in sequence to obtain high-nickel ternary cathode material LiNi. 0.83 Co 0.05 Mn 0.11 In 0.01 B 0.01 O2.

[0090] Example 6

[0091] In this implementation, In₂O₃ and SiO₂ are selected as additives, LiOH·H₂O is selected as the lithium source, and Ni is selected as the precursor containing nickel, cobalt, and manganese. 0.83 Co 0.06 Mn 0.11 (OH)2.

[0092] The preparation method of the high-nickel ternary cathode material in this embodiment includes the following steps:

[0093] (1) Weigh the precursor Ni 0.83 Co 0.06 Mn 0.11 (OH)2, LiOH·H2O, In2O3 and SiO, Ni, in molar ratio 0.83 Co 0.06 Mn 0.11 (OH)2:LiOH·H2O:In2O3:SiO=1:1.04:0.005:0.01. The above four compounds were placed in an air jet mixer and mixed at a speed of 850 rpm / min for 40 min. After thorough mixing, a mixture was obtained.

[0094] (2) The mixture was transferred to an atmosphere furnace for high-temperature sintering in a sintering atmosphere. First, the temperature was increased to 550℃ at a heating rate of 2.5℃ / min and calcined for 5.5h. Then, the temperature was increased to 760℃ at a heating rate of 2.5℃ / min and calcined for 13.5h. The oxygen content in the sintering atmosphere was 99 vol%. The furnace was cooled, and the resulting material was subjected to roller crushing, ultracentrifugal grinding, and 325-mesh sieve treatment to obtain high-nickel ternary cathode material LiNi. 0.83 Co 0.05 Mn 0.11 In 0.01 Si 0.01 O2.

[0095] Comparative Example 1 (Undoped)

[0096] In this comparative example, LiOH·H2O was used as the lithium source, and Ni was used as the precursor containing nickel, cobalt, and manganese. 0.83 Co 0.06 Mn 0.11 (OH)2.

[0097] The preparation method of the high-nickel ternary cathode material in this comparative example includes the following steps:

[0098] (1) Weigh the precursor Ni 0.83 Co 0.06 Mn 0.11 (OH)2 and LiOH·H2O, in molar ratios, Ni 0.83 Co 0.06 Mn 0.11 (OH)2:LiOH·H2O=1:1.04. The two compounds were mixed in an air jet mixer at a speed of 850 rpm / min for 40 min. After thorough mixing, a mixture was obtained.

[0099] (2) The mixture was transferred to an atmosphere furnace for high-temperature sintering in a sintering atmosphere. First, the temperature was increased to 550℃ at a heating rate of 2.5℃ / min and calcined for 5.5h. Then, the temperature was increased to 760℃ at a heating rate of 2.5℃ / min and calcined for 13.5h. The oxygen content in the sintering atmosphere was 99 vol%. The furnace was cooled, and the resulting material was subjected to roller crushing, ultracentrifugal grinding, and 325-mesh sieve treatment to obtain high-nickel ternary cathode material LiNi. 0.83 Co 0.06 Mn 0.11 O2.

[0100] Comparative Example 2 (doped with only Al)

[0101] In this comparative example, Al2O3 was used as the additive, LiOH·H2O was used as the lithium source, and Ni was used as the precursor containing nickel, cobalt, and manganese. 0.83 Co 0.06 Mn 0.11 (OH)2.

[0102] The preparation method of the high-nickel ternary cathode material in this comparative example includes the following steps:

[0103] (1) Weigh the ternary precursor Ni 0.83 Co 0.06 Mn 0.11 (OH)2, LiOH·H2O and Al2O3, Ni, in molar ratio 0.83 Co 0.06 Mn 0.11 (OH)2:LiOH·H2O:Al2O3=1:1.04:0.005. The above three compounds were placed in an air jet mixer and mixed at a speed of 850 rpm / min for 40 min. After thorough mixing, a mixture was obtained.

[0104] (2) The mixture was transferred to an atmosphere furnace for high-temperature sintering in a sintering atmosphere. First, the temperature was increased to 550℃ at a heating rate of 2.5℃ / min and calcined for 5.5h. Then, the temperature was increased to 760℃ at a heating rate of 2.5℃ / min and calcined for 13.5h. The oxygen content in the sintering atmosphere was 99 vol%. The furnace was cooled, and the resulting material was subjected to roller crushing, ultracentrifugal grinding, and 325-mesh sieve treatment to obtain high-nickel ternary cathode material LiNi. 0.83 Co 0.05 Mn 0.11 Al 0.01 O2.

[0105] Comparative Example 3 (doped with only element B)

[0106] In this comparative example, B2O3 was used as the additive, LiOH·H2O was used as the lithium source, and Ni was used as the precursor containing nickel, cobalt, and manganese. 0.83 Co 0.06 Mn 0.11 (OH)2.

[0107] The preparation method of the high-nickel ternary cathode material in this comparative example includes the following steps:

[0108] (1) Weigh the ternary precursor Ni 0.83 Co 0.06 Mn 0.11 (OH)2, LiOH·H2O and B2O3, Ni, in molar ratios 0.83 Co 0.06 Mn0.11 (OH)2:LiOH·H2O:B2O3=1:1.04:0.01. The above three compounds were placed in an air jet mixer and mixed at a speed of 850 rpm / min for 40 min. After thorough mixing, a mixture was obtained.

[0109] (2) The mixture was transferred to an atmosphere furnace for high-temperature sintering in a sintering atmosphere. First, the temperature was increased to 550℃ at a heating rate of 2.5℃ / min and calcined for 5.5h. Then, the temperature was increased to 760℃ at a heating rate of 2.5℃ / min and calcined for 13.5h. The oxygen content in the sintering atmosphere was 99 vol%. The furnace was cooled, and the resulting material was subjected to roller crushing, ultracentrifugal grinding, and 325-mesh sieve treatment to obtain high-nickel ternary cathode material LiNi. 0.83 Co 0.06 Mn 0.11 B 0.02 O2.

[0110] Comparative Example 4 (doped with only In element)

[0111] In this comparative example, In₂O₃ was used as the additive, LiOH·H₂O was used as the lithium source, and Ni was used as the precursor containing nickel, cobalt, and manganese. 0.83 Co 0.06 Mn 0.11 (OH)2.

[0112] The preparation method of the high-nickel ternary cathode material in this comparative example includes the following steps:

[0113] (1) Weigh the ternary precursor Ni 0.83 Co 0.06 Mn 0.11 (OH)2, LiOH·H2O and Al2O3, Ni, in molar ratio 0.83 Co 0.06 Mn 0.11 (OH)2:LiOH·H2O:In2O3=1:1.04:0.005. The above three compounds were placed in an air jet mixer and mixed at a speed of 850 rpm / min for 40 min. After thorough mixing, a mixture was obtained.

[0114] (2) The mixture was transferred to an atmosphere furnace for high-temperature sintering in a sintering atmosphere. First, the temperature was increased to 550℃ at a heating rate of 2.5℃ / min and calcined for 5.5h. Then, the temperature was increased to 760℃ at a heating rate of 2.5℃ / min and calcined for 13.5h. The oxygen content in the sintering atmosphere was 99 vol%. The furnace was cooled, and the resulting material was subjected to roller crushing, ultracentrifugal grinding, and 325-mesh sieve treatment to obtain high-nickel ternary cathode material LiNi.0.83 Co 0.05 Mn 0.11 In 0.01 O2.

[0115] Comparative Example 5 (doped with only Si)

[0116] In this comparative example, SiO was used as the additive, LiOH·H2O was used as the lithium source, and Ni was used as the precursor containing nickel, cobalt, and manganese. 0.83 Co 0.06 Mn 0.11 (OH)2.

[0117] The preparation method of the high-nickel ternary cathode material in this comparative example includes the following steps:

[0118] (1) Weigh the ternary precursor Ni 0.83 Co 0.06 Mn 0.11 (OH)₂, LiOH·H₂O and SiO, Ni, in molar ratio. 0.83 Co 0.06 Mn 0.11 (OH)2:LiOH·H2O:SiO=1:1.04:0.01. The above three compounds were placed in an air jet mixer and mixed at a speed of 850 rpm / min for 40 min. After thorough mixing, a mixture was obtained.

[0119] (2) The mixture was transferred to an atmosphere furnace for high-temperature sintering in a sintering atmosphere. First, the temperature was increased to 550℃ at a heating rate of 2.5℃ / min and calcined for 5.5h. Then, the temperature was increased to 760℃ at a heating rate of 2.5℃ / min and calcined for 13.5h. The oxygen content in the sintering atmosphere was 99 vol%. The furnace was cooled, and the resulting material was subjected to roller crushing, ultracentrifugal grinding, and 325-mesh sieve treatment to obtain high-nickel ternary cathode material LiNi. 0.83 Co 0.06 Mn 0.11 Si 0.01 O2.

[0120] ICP, SEM, XRD, specific surface area and residual alkali content tests

[0121] The composition of the high-nickel ternary cathode materials prepared in each embodiment and comparative example was determined using an ICP-AES analyzer.

[0122] The high-nickel ternary cathode material prepared in Example 1 and the high-nickel ternary cathode material prepared in Comparative Example 1 were characterized by SEM. Figure 1 The high-nickel ternary cathode material LiNi prepared in Example 1 0.83 Co0.05 Mn 0.11 Al 0.01 B 0.02 SEM image of O2 at 10000x magnification. Figure 2 The high-nickel ternary cathode material LiNi prepared in Comparative Example 1 0.83 Co 0.06 Mn 0.11 SEM image of O2 at 10000x magnification.

[0123] from Figure 1 and Figure 2 As can be seen, the high-nickel ternary cathode materials prepared in Example 1 and Comparative Example 1 are both composed of secondary microspheres assembled from primary nanoparticles, with an average size of about 10 μm; furthermore, compared with... Figure 1 and Figure 2 It can be observed that the primary particles of the high-nickel ternary cathode material prepared in Example 1 have a stronger grainy texture, while the primary particles of the high-nickel ternary cathode material prepared in Comparative Example 1 have a smoother surface. This is mainly because the B element is difficult to replace or occupy interstitial sites in the bulk lattice during competitive doping and thus becomes enriched on the surface.

[0124] Figure 3 The high-nickel ternary cathode material LiNi prepared in Example 1 0.83 Co 0.05 Mn 0.11 Al 0.01 B 0.02 XRD pattern of O2. From Figure 3 As can be seen, the high-nickel ternary cathode material prepared in Example 1 has a layered structure with an α-NaFeO2 rhombic structure of R-3m space group. LiNi co-doped with Al and B elements... 0.83 Co 0.05 Mn 0.11 Al 0.01 B 0.02 O2 has high crystallinity and no excess impurity peaks; in addition, LiNi 0.83 Co 0.05 Mn 0.11 Al 0.01 B 0.02 The peak intensity of the O2 diffraction peak (003) / (104) is greater than 1.2, indicating that the Li / Ni mixing is weak.

[0125] The specific surface area and residual alkali content of the high-nickel ternary cathode materials prepared in Examples 1-6 and Comparative Examples 1-5 were tested, and the results are shown in Table 1.

[0126] The test methods for specific surface area and residual alkali content are as follows:

[0127] 1. Specific surface area test method: Measured using a specific surface area analyzer according to GB / T19587-2017;

[0128] 2. Residual alkali content test method: The prepared high-nickel ternary cathode material and deionized water were mixed at a mass ratio of 5:100 and stirred at a speed of 200 rpm / min-400 rpm / min for 5 min. After filtering all the material using a vacuum filtration pump, the residual LiOH and residual Li2CO3 content on the surface of the high-nickel ternary cathode material were determined by equivalence point titration with 0.1M hydrochloric acid solution.

[0129] Electrochemical performance testing

[0130] The high-nickel ternary cathode materials prepared in Examples 1-6 and Comparative Examples 1-5 were used as active materials. SP was selected as the conductive agent, PVDF as the binder, and NMP as the solvent. The active material, conductive agent, and binder were mixed uniformly at a mass ratio of 96.5:1.5:2 to form a slurry, which was then coated onto aluminum foil. After drying, the slurry was cut into cathode discs and assembled into coin cells in a glove box. The electrolyte was 1M LiPF6 dissolved in a mixture of ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) (volume ratio 1:1:1). After assembly, the coin cells were allowed to stand for 12 hours before electrochemical performance testing. The results are shown in Table 1 and... Figure 4 As shown.

[0131] Discharge specific capacity test conditions: The coin cells assembled in each embodiment and each comparative example were subjected to constant current charge-discharge tests using a battery testing system (CT2001A, LAND). The initial capacity test temperature was room temperature (25°C), and the current was 0.1C (current density set to 1C = 200mA g). -1 The voltage range is 2.8V~4.25V (vs. Li / Li). + ).

[0132] High-temperature cycling performance test conditions: The coin cells assembled in each embodiment and each comparative example were cycled 50 times at 45°C and a current density of 0.3C.

[0133] Table 1

[0134]

[0135] From Table 1 and Figure 4It can be seen that the coin cells of Example 1 and Comparative Example 1 retained 97.91% and 91.42% of their capacity after 50 cycles at 45°C and a current density of 0.3C, respectively. Compared with the high-nickel ternary cathode material of Comparative Example 1, the high-nickel ternary cathode material of Example 1 was competitively co-doped with Al and B elements, resulting in a significant improvement in the cycle stability of Example 1. This is mainly because the uniform bulk distribution of Al and the surface enrichment of B elements synergistically improve the crystal structure and surface chemical structure of the high-nickel ternary cathode material. Compared with Examples 1-6, the high-nickel ternary cathode materials prepared in Comparative Examples 2-5 were doped with only X or Y elements. The coin cells of Comparative Examples 2-5 exhibited worse high-temperature cycle performance at 45°C and 0.3C than those of Examples 1-6, indicating that the high-nickel cathode materials in Examples 1-6 significantly improved their cycle performance and thermal stability through co-doping with X and Y elements.

[0136] In summary, by doping high-nickel ternary cathode materials with elements X and Y, a competitive layered doping effect is achieved. This competitive layered doping ensures that during the co-doping process, element X undergoes uniform bulk doping, while element Y is enriched on the material surface. Uniform bulk lattice doping of element X effectively mitigates the sudden contraction of lattice parameters in the c-direction, reducing the collapse of lithium atom interlayer spacing at the end of charging, thereby reducing the anisotropy of the layered structure and lattice collapse in the c-direction. The surface-enriched Y layer helps form a stable surface / interface layer during cycling, suppressing surface reconstruction. Therefore, competitive layered doping can synergistically improve the crystal structure and surface chemical structure, significantly enhancing the cycle stability of high-nickel ternary cathode materials and effectively solving the problems of severe capacity and voltage decay during cycling.

[0137] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0138] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A high-nickel ternary cathode material, characterized in that, Including chemical formula LiNi x Co y Mn z X a Y b The material is O2, wherein 0.8 ≤ x < 0.96, y > 0, z > 0, 0.001 ≤ a ≤ 0.05, 0.001 ≤ b ≤ 0.05, x + y + z + a = 1, X and Y are dopant elements, X includes one or more of Al and In, Y includes Si, and the dopant element X is distributed in the chemical formula LiNi x Co y Mn z X a Y b In the bulk lattice of the O2 material, the dopant element Y is enriched in the material with the chemical formula LiNi. x Co y Mn z X a Y b The surface area of ​​the O2 material, specifically the high-nickel ternary cathode material, is 0.4 m². 2 / g~0.7m 2 / g; The preparation method of the high-nickel ternary cathode material includes the following steps: An additive, a lithium source, and a precursor containing nickel, cobalt, and manganese are mixed to obtain a mixture, wherein the additive contains dopant element X and dopant element Y. The mixture is sintered to obtain the high-nickel ternary cathode material; The sintering process includes the following steps: placing the mixture in an oxygen-containing sintering atmosphere and sintering at 450℃~600℃ for 2h~10h, and then sintering at 650℃~900℃ for 10h~20h.

2. The high-nickel ternary cathode material as described in claim 1, characterized in that, z > y.

3. The high-nickel ternary cathode material according to claim 1, characterized in that, The precursor containing nickel, cobalt, and manganese includes the chemical formula Ni. m Co n Mn 1-m-n The material is (OH)2, where 0.8≤m<0.96, n>0, and m+n<1.

4. The high-nickel ternary cathode material according to claim 1, characterized in that, The additives include one or more of the following: oxides, carbonates, hydroxides, and acetates of dopant elements X and Y.

5. The high-nickel ternary cathode material according to claim 1, characterized in that, The lithium source includes one or more of lithium hydroxide, lithium carbonate, lithium acetate, and lithium nitrate.

6. The high-nickel ternary cathode material according to claim 1, characterized in that, The molar ratio of lithium in the lithium source to the precursor containing nickel, cobalt and manganese is (1.01~1.06):

1.

7. The high-nickel ternary cathode material according to any one of claims 1 to 6, characterized in that, The percentage of the amount of dopant element X in the mixture relative to the total amount of the additive, the lithium source, and the precursor containing nickel, cobalt, and manganese is 0.1% to 0.6%. The amount of dopant element Y in the mixture is 0.4% to 1% of the total amount of the additive, the lithium source, and the precursor containing nickel, cobalt, and manganese.

8. The high-nickel ternary cathode material according to any one of claims 2 to 6, characterized in that, The high-nickel ternary cathode material contains 0.05wt% to 0.15wt% of Li2CO3 by mass.

9. The high-nickel ternary cathode material according to claim 1, characterized in that, The volume percentage of oxygen in the oxygen-containing sintering atmosphere is ≥97%.

10. A positive electrode plate, characterized in that, Includes the high-nickel ternary cathode material as described in any one of claims 1 to 9.

11. A secondary battery, characterized in that, Includes the positive electrode sheet as described in claim 10.

12. An electrical appliance, characterized in that, Includes the secondary battery as described in claim 11.

Images