High-entropy doped positive electrode material, and preparation method therefor and use thereof

Abstract

The present invention relates to a high-entropy doped positive electrode material, and a preparation method therefor and the use thereof. The high-entropy doped positive electrode material comprises a material having the chemical formula of LiNixCoyMnzBaMbO2, wherein 0.80≤x＜0.98, 0＜y＜0.2, 0＜z＜0.2, a＞0, b＞0, a≥b, x+y+z+a+b＝1, and M comprises at least four of Al, Zr, Sr, Sn, Sb, Si, Ba, Y, W, Ta, Ti, Mo, Nb, La, Ta and Ce. The high-entropy doped positive electrode material can have both relatively high specific capacity and cycling stability.

Description

High-entropy doped cathode materials, their preparation methods and applications

[0001] This application claims priority to Chinese Patent Application No. 202410987708.4, filed on July 23, 2024, entitled "High-entropy doped cathode material and its preparation method and application", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of lithium-ion battery technology, and in particular to a high-entropy doped cathode material, its preparation method, and its application. Background Technology

[0003] High-nickel ternary cathode materials have become a research hotspot in lithium-ion battery cathode materials due to their advantages such as low cost and high energy density. However, in high-nickel ternary cathode materials, with increasing Ni content, failure modes such as chemical performance degradation, oxygen escape, and the formation of new rock salt phases intensify, leading to poor cycle stability. Currently, doping high-nickel cathode materials is mainly used to improve their crystal structure and surface structure stability, thereby improving their cycle stability. However, traditional doping methods, while improving the cycle stability of high-nickel cathode materials, also lead to a decrease in specific capacity. In other words, traditionally doped cathode materials struggle to simultaneously possess high cycle stability and specific capacity.

[0004] Summary of the Invention

[0005] Therefore, it is necessary to provide a high-entropy doped cathode material, its preparation method, and its application. The high-entropy doped cathode material of this application can simultaneously possess high specific capacity and cycle stability.

[0006] Firstly, this application provides a high-entropy doped cathode material, including the chemical formula LiNi. x Co y Mn z B a M b The material of O2 has the following properties: 0.80≤x<0.98, 0<y<0.2, 0<z<0.2, a>0, b>0, a≥b, x+y+z+a+b=1, and M includes at least four of Al, Zr, Sr, Sn, Sb, Si, Ba, Y, W, Ta, Ti, Mo, Nb, La, Ta and Ce.

[0007] In some of these implementations, 0.90 ≤ x < 0.98.

[0008] In some implementations, 0.01 ≤ a ≤ 0.05.

[0009] In some implementations, 0.01 ≤ b ≤ 0.05.

[0010] In some implementations, 0.01 ≤ y ≤ 0.05.

[0011] In some implementations, 0.01 ≤ z ≤ 0.05.

[0012] In some embodiments, the Dv50 of the secondary particles of the high-entropy doped cathode material is 2 μm to 5 μm.

[0013] In some embodiments, the specific surface area of ​​the high-entropy doped cathode material is 0.5 m². 2 / g~1.5m 2 / g.

[0014] Secondly, this application provides a method for preparing a high-entropy doped cathode material, comprising the following steps:

[0015] A mixed raw material is obtained by mixing a doping source, a boron source, a lithium source, and a nickel-cobalt-manganese precursor;

[0016] The mixed raw materials are subjected to sintering treatment;

[0017] The doping source includes at least four of the following: Al, Zr, Sr, Sn, Sb, Si, Ba, Y, W, Ta, Ti, Mo, Nb, La, Ta, and Ce.

[0018] The nickel-cobalt-manganese precursor comprises Ni m Co n Mn 1-m-n The material is (OH)2, where 0.80≤m<0.98, n>0, and m+n<1.

[0019] In some embodiments, the molar ratio of lithium in the lithium source to the nickel-cobalt-manganese precursor is (1.01 to 1.06):1.

[0020] In some embodiments, the boron source comprises 1% to 5% of the molar percentage of the mixed raw materials.

[0021] In some embodiments, the M element in the doping source accounts for 0.5% to 5% of the molar percentage of the mixed raw material.

[0022] In some embodiments, the boron source includes at least one of H3BO3 and B2O3.

[0023] In some embodiments, the doping source includes at least one of the oxides, carbonates, hydroxides, and acetates of M.

[0024] In some embodiments, the lithium source includes at least one of lithium hydroxide, lithium carbonate, lithium acetate, lithium nitrate, and lithium oxalate.

[0025] In some embodiments, sintering the mixed raw materials includes the following steps:

[0026] The mixed raw materials are pre-sintered in an oxygen-containing gas atmosphere;

[0027] After heating, the mixed raw materials are subjected to a first sintering process to obtain a sintered material;

[0028] The sintering material and cobalt hydroxide are mixed and then subjected to a second sintering under an oxygen-containing gas atmosphere.

[0029] In some embodiments, the pre-sintering temperature is 450°C to 650°C.

[0030] In some embodiments, the pre-sintering time is 2h to 10h.

[0031] In some embodiments, the temperature of the first sintering is 700°C to 900°C.

[0032] In some embodiments, the first sintering time is 10h to 20h.

[0033] In some embodiments, the second sintering temperature is 580°C to 680°C.

[0034] In some embodiments, the second sintering time is 2h to 10h.

[0035] In some embodiments, the oxygen-containing gas contains more than 97% oxygen by volume.

[0036] Thirdly, this application provides a positive electrode sheet, comprising: a current collector and an active layer located on the surface of the current collector, wherein the active layer comprises the high-entropy doped positive electrode material described in any one of the above claims or the high-entropy doped positive electrode material prepared by the preparation method of the high-entropy doped positive electrode material described in any one of the above claims.

[0037] Fourthly, this application provides a secondary battery, including the aforementioned positive electrode.

[0038] Fifthly, this application provides an electrical device including the aforementioned secondary battery.

[0039] In the aforementioned high-entropy doped cathode materials, high-nickel cathode materials are doped with boron (B) and at least four of the following doping elements: Al, Zr, Sr, Sn, Sb, Si, Ba, Y, W, Ta, Ti, Mo, Nb, La, Ta, and Ce. During the doping process, boron is the dominant element. B adsorbs onto the (003) crystal plane, reducing the surface energy of the (003) plane and increasing the surface energy of the (104) crystal plane. Therefore, high-entropy doped cathode materials tend to grow along the (003) crystal plane, thereby refining and homogenizing the primary particle size, which significantly alleviates stress unevenness, improves crack resistance, and enhances mechanical stability. Furthermore, by doping with five or more elements, the high-entropy characteristic enables a positive synergistic effect among the doping elements, thereby improving the electrochemical performance of the cathode material. Meanwhile, the diversity of doping elements leads to short-range interruptions in the crystal structure of the cathode material, which not only improves the cathode material's tolerance to structural evolution during electrochemical processes but also induces defects that facilitate electron and ion migration, thereby increasing the specific capacity of the high-entropy doped cathode material. The high-entropy doped cathode material of this application can simultaneously possess high specific capacity and cycle stability. Attached Figure Description

[0040] Figure 1 is a scanning electron microscope image of the high-entropy doped cathode material provided in Embodiment 1 of this application;

[0041] Figure 2 is a scanning electron microscope image of the high-entropy cathode material provided in Comparative Example 1 of this application;

[0042] Figure 3 is a comparison chart of the cycle retention rates of Example 1 and Comparative Example 1 of this application. Detailed Implementation

[0043] 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.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0045] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0046] One embodiment of this application provides a high-entropy doped cathode material, including the chemical formula LiNi. x Co y Mn z B a M b The material of O2 has the following properties: 0.80≤x<0.98, 0<y<0.2, 0<z<0.2, a>0, b>0, a≥b, x+y+z+a+b=1, and M includes at least four of Al, Zr, Sr, Sn, Sb, Si, Ba, Y, W, Ta, Ti, Mo, Nb, La, Ta and Ce.

[0047] In some implementations, the number of moles of each element in M ​​is the same.

[0048] In some embodiments, M includes any four of Al, Zr, Sr, Sn, Sb, Si, Ba, Y, W, Ta, Ti, Mo, Nb, La, Ta, and Ce; and the molar ratio of any four of Al, Zr, Sr, Sn, Sb, Si, Ba, Y, W, Ta, Ti, Mo, Nb, La, Ta, and Ce is 1:1:1:1.

[0049] In some embodiments, M includes any five of Al, Zr, Sr, Sn, Sb, Si, Ba, Y, W, Ta, Ti, Mo, Nb, La, Ta, and Ce; and the molar ratio of any five of Al, Zr, Sr, Sn, Sb, Si, Ba, Y, W, Ta, Ti, Mo, Nb, La, Ta, and Ce is 1:1:1:1:1.

[0050] In the aforementioned high-entropy doped cathode materials, the cathode material is doped with at least four doping elements selected from Bo (B) and Al, Zr, Sr, Sn, Sb, Si, Ba, Y, W, Ta, Ti, Mo, Nb, La, Ta, and Ce. During the doping process, B is the dominant element, as it can adsorb onto the (003) crystal plane, reducing the surface energy of the (003) crystal plane and increasing the surface energy of the (104) crystal plane. Therefore, the high-entropy doped cathode material tends to grow along the (003) crystal plane, thereby refining and homogenizing the primary particle size, which can significantly alleviate stress unevenness, improve crack resistance, and enhance mechanical stability. Furthermore, by doping with five or more elements, the high-entropy characteristic can generate a positive synergistic effect among the doping elements, thereby improving the electrochemical performance of the cathode material. At the same time, the diversity of doping elements leads to short-range interruptions in the crystal structure of the cathode material, which can improve the cathode material's tolerance to structural evolution during electrochemical processes and induce defects that are conducive to electron and ion migration, thus increasing the specific capacity of the high-entropy doped cathode material. The high-entropy doped cathode material of this application can simultaneously possess high specific capacity and cycle stability.

[0051] In some implementations, 0.90 ≤ x < 0.98. Alternatively, x can be 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.975, 0.979, 0.9799, or 0.97999. Or, x can be within the range of any two of the above values.

[0052] In some implementations, 0.01 ≤ a ≤ 0.05.

[0053] In some implementations, 0.01 ≤ b ≤ 0.05.

[0054] When the values ​​of a and b are too small, i.e., the doping amount is too low, the entropy value of the cathode material is too low, resulting in lower specific capacity and cycle stability. When the values ​​of a and b are too large, the doping amount is too high. Due to the poor electrochemical activity of the dopant element M, the excessively high doping amount leads to a lower specific capacity of the cathode material.

[0055] Optionally, a can be 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, or 0.05. Alternatively, a can be within the range of any two of the above values.

[0056] Optionally, b can be 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, or 0.05. Alternatively, b can be within the range of any two of the above values.

[0057] In some implementations, 0.01 ≤ y ≤ 0.05. Optionally, y is 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, or 0.05. Alternatively, y can also be within the range of any two of the above values.

[0058] In some implementations, 0.01 ≤ z ≤ 0.05. Optionally, z is 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, or 0.05. Alternatively, z can also be within the range of any two of the above values.

[0059] In some embodiments, the high-entropy doped cathode material is a polycrystalline high-entropy doped cathode material.

[0060] In some embodiments, the high-entropy doped cathode material includes multiple secondary particles, which are formed by the agglomeration of primary particles.

[0061] In some embodiments, the Dv50 of the secondary particles in the high-entropy doped cathode material is 2 μm to 5 μm. High-entropy doped cathode materials with a Dv50 of secondary particles within this range can be easily compounded with large-particle cathode active materials.

[0062] Optionally, the Dv50 of the secondary particles of the high-entropy doped cathode material can be 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3 μm, 3.2 μm, 3.4 μm, 3.6 μm, 3.8 μm, 4 μm, 4.2 μm, 4.4 μm, 4.6 μm, 4.8 μm, or 5 μm. Alternatively, the Dv50 of the secondary particles of the high-entropy doped cathode material can also be within the range of any two of the above values.

[0063] In some embodiments, the specific surface area of ​​the high-entropy doped cathode material is 0.5 m². 2 / g~1.5m 2 / g.

[0064] Optionally, the specific surface area of ​​the high-entropy doped cathode material is 0.5 m². 2 / g, 0.6m 2 / g, 0.7m 2 / g, 0.8m 2 / g, 0.9m 2 / g, 1m 2 / g, 1.1m 2 / g, 1.2m 2 / g, 1.3m 2 / g, 1.4m 2 / g or 1.5m 2 / g. Alternatively, the specific surface area of ​​the high-entropy doped cathode material can also be within the range between any two of the above specific surface areas.

[0065] Another embodiment of this application provides a method for preparing a high-entropy doped cathode material, comprising the following steps:

[0066] A mixed raw material is obtained by mixing a doping source, a boron source, a lithium source, and a nickel-cobalt-manganese precursor;

[0067] The mixed raw materials are sintered.

[0068] The doping sources include at least four of the following: Al, Zr, Sr, Sn, Sb, Si, Ba, Y, W, Ta, Ti, Mo, Nb, La, Ta, and Ce.

[0069] Nickel-cobalt-manganese precursors include those with the chemical formula Ni m Co n Mn 1-m-n The material is (OH)2, where 0.80≤m<0.98, n>0, and m+n<1.

[0070] Optionally, 0.90 ≤ m < 0.98. Further optionally, m can be 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.975, 0.979, 0.9799, or 0.97999. Alternatively, m can also be within the range of any two of the above values.

[0071] Optionally, 0.01 ≤ n ≤ 0.05. Further optionally, n can be 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, or 0.05. Alternatively, n can also be within the range of any two of the above values.

[0072] In some embodiments, the molar ratio of lithium to nickel-cobalt-manganese precursor in the lithium source is (1.01 to 1.06):1.

[0073] Optionally, the molar ratio of lithium to nickel-cobalt-manganese precursor in the lithium source is 1.01:1, 1.02:1, 1.03:1, 1.04:1, 1.05:1, or 1.06:1. Alternatively, the molar ratio of lithium to nickel-cobalt-manganese precursor in the lithium source can also be within the range of any two of the above molar ratios.

[0074] In some embodiments, the boron element in the boron source accounts for 1% to 5% of the molar percentage of the mixed raw materials.

[0075] Optionally, the molar percentage of boron in the boron source relative to the mixed raw materials is 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%. Alternatively, the molar percentage of boron in the boron source relative to the mixed raw materials may also be within the range of any two of the above percentages.

[0076] In some embodiments, the M element in the dopant source accounts for 0.5% to 5% of the molar percentage of the mixed raw materials.

[0077] Optionally, the molar percentage of element M in the doping source relative to the mixed raw materials is 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%. Alternatively, the molar percentage of element M in the doping source relative to the mixed raw materials may also be within the range of any two of the above percentages.

[0078] In some embodiments, the doping source includes at least one of the oxides, carbonates, hydroxides, and acetates of M.

[0079] In some embodiments, the lithium source includes at least one of lithium hydroxide, lithium carbonate, lithium acetate, lithium nitrate, and lithium oxalate.

[0080] In some embodiments, sintering the mixed raw materials includes the following steps:

[0081] The mixed raw materials are pre-sintered in an oxygen-containing gas atmosphere;

[0082] After heating, the mixed raw materials are subjected to a first sintering process to obtain sintered material;

[0083] Under an oxygen-containing gas atmosphere, the sintering material and cobalt hydroxide are mixed and then subjected to a second sintering.

[0084] In sintered materials, unreacted residual alkali may remain on the surface, hindering lithium extraction and resulting in poor performance of the cathode material. Lithium cobalt oxide can be formed by reacting cobalt hydroxide with the residual alkali on the material surface. Lithium cobalt oxide possesses electrochemical activity and good conductivity, enabling the prepared cathode material to have lower impedance, higher specific capacity, and higher cycle stability.

[0085] In some embodiments, the pre-sintering temperature is 450°C to 650°C.

[0086] Within the aforementioned pre-sintering temperature range, the mixing effect between the nickel-cobalt-manganese precursor and the lithium source is good. If the pre-sintering temperature is too low, the lithium source is difficult to melt, and the reaction between it and the nickel-cobalt-manganese precursor is insufficient. If the pre-sintering temperature is too high, it will lead to increased lithium-nickel mixing. Optionally, the pre-sintering temperature can be 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, 610℃, 620℃, 630℃, 640℃, or 650℃. Alternatively, the pre-sintering temperature can also be within any two of the above temperature ranges.

[0087] In some embodiments, the pre-sintering heating rate is 1–5 °C / min. Optionally, the pre-sintering heating rate is 1 °C / min, 1.5 °C / min, 2 °C / min, 2.5 °C / min, 3 °C / min, 3.5 °C / min, 4 °C / min, 4.5 °C / min, or 5 °C / min. Alternatively, the pre-sintering heating rate may also be within the range of any two of the above heating rates.

[0088] In some embodiments, the pre-sintering time is 2h to 10h.

[0089] Optionally, the pre-sintering time can be 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, or 10h. Alternatively, the pre-sintering time can also be within any two of the above-mentioned times.

[0090] In some embodiments, the temperature of the first sintering is 700°C to 900°C.

[0091] Within the aforementioned temperature range for the first sintering, the grain growth of the cathode material is optimal. If the first sintering temperature is too low, the crystallinity of the cathode material will be insufficient, resulting in excessively small primary grains, exacerbating side reactions, and ultimately leading to irregular morphology of the cathode material. If the first sintering temperature is too high, it will cause excessive growth of secondary particles in the cathode material, resulting in single-crystal cathode material. Optionally, the first sintering temperature is 700℃, 750℃, 800℃, 850℃, or 900℃. Alternatively, the first sintering temperature can fall within any two of the aforementioned temperature ranges.

[0092] In some embodiments, the heating rate of the first sintering is 1–5 °C / min. Optionally, the heating rate of the first sintering is 1 °C / min, 1.5 °C / min, 2 °C / min, 2.5 °C / min, 3 °C / min, 3.5 °C / min, 4 °C / min, 4.5 °C / min, or 5 °C / min. Alternatively, the heating rate of the first sintering may also be within the range of any two of the above heating rates.

[0093] In some embodiments, the first sintering time is 10h to 20h.

[0094] Optionally, the first sintering time is 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, or 20h. Alternatively, the first sintering time can also be within any two of the above times.

[0095] In some of these embodiments, the molar ratio of the sinter to cobalt hydroxide is 1:(0.005 to 0.02). Alternatively, the molar ratio of the sinter to cobalt hydroxide is 1:0.005, 1:0.008, 1:0.01, 1:0.015, or 0.02.

[0096] In some embodiments, the second sintering temperature is 580°C to 680°C.

[0097] Within the aforementioned second sintering temperature range, the reaction between cobalt hydroxide and residual alkali on the sintering material surface is relatively effective. If the second sintering temperature is too low, the reaction between cobalt hydroxide and residual alkali is insufficient. If the second sintering temperature is too high, the diffusion rate of cobalt will be too fast, potentially causing cobalt to penetrate deep into the crystal lattice of the sintering material, leading to instability in the crystal structure of the cathode material. Within the aforementioned second sintering temperature range, the reaction between cobalt hydroxide and residual alkali can be controlled to occur only on the surface of the sintering material. Optionally, the second sintering temperature can be 580℃, 600℃, 620℃, 640℃, 660℃, or 680℃. Alternatively, the second sintering temperature can also be within the range of any two of the aforementioned temperatures.

[0098] In some embodiments, the second sintering time is 2h to 10h.

[0099] Optionally, the second sintering time is 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, or 10h. Alternatively, the second sintering time can also be within any two of the above-mentioned times.

[0100] In some of these embodiments, the oxygen-containing gas contains more than 97% oxygen by volume.

[0101] Optionally, the volume percentage of oxygen in the oxygen-containing gas is 97% to 100%. More preferably, the volume percentage of oxygen in the oxygen-containing gas is 97%, 97.5%, 98%, 98.5%, 99%, 99.5%, or 100%. Alternatively, the volume percentage of oxygen in the oxygen-containing gas may also be within the range of any two of the above percentages.

[0102] Another embodiment of this application provides a positive electrode sheet, including: a current collector and an active layer located on the surface of the current collector, wherein the active layer comprises a high-entropy doped positive electrode material according to any one of the above claims or a high-entropy doped positive electrode material prepared by any one of the above-mentioned methods.

[0103] Another embodiment of this application provides a secondary battery, including the above-described positive electrode sheet.

[0104] Another embodiment of this application provides an electrical device including the aforementioned secondary battery.

[0105] The technical solution of the present invention will be described in detail below with reference to specific embodiments. It should be understood that these embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention. For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this invention, or follow experimental manuals or conventional conditions in the art, or follow the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0106] In the specific embodiments described below, the measurement parameters involving raw material components may have slight deviations within the weighing accuracy range unless otherwise specified. Temperature and time parameters are subject to acceptable deviations due to instrument testing accuracy or operational precision.

[0107] Example 1

[0108] In this embodiment, the boron source is H3BO3, the doping sources are ZrO2, SrCO3, Al2O3, and Nb2O5, the lithium source is LiOH·H2O, and the nickel-cobalt-manganese precursor is Ni. 0.96 Co 0.03 Mn 0.01 The Dv50 of the (OH)2, nickel-cobalt-manganese precursor is 2 μm to 3 μm. The prepared high-entropy doped cathode material has a Dv50 of 2 μm to 3 μm and a specific surface area of ​​1.016 m². 2 / g.

[0109] Preparation methods of high-entropy doped cathode materials:

[0110] (1) Weigh Ni in a molar ratio of 1:1.04:0.04:0.01:0.01:0.005:0.005. 0.96 Co 0.03 Mn 0.01 The compounds (OH)2, LiOH·H2O, H3BO3, ZrO2, SrCO3, Al2O3 and Nb2O5 were mixed in an air jet mixer at a speed of 1200 rpm / min for 40 min to obtain a mixed raw material.

[0111] (2) The mixed raw materials were transferred to a box furnace for high-temperature sintering in an oxygen atmosphere. First, the temperature was raised to 630℃ at a heating rate of 2.5℃ / min and calcined for 6 hours. Then, the temperature was raised to 720℃ at a heating rate of 2.5℃ / min and calcined for 16 hours. The oxygen content in the sintering atmosphere was 99 vol%. After cooling in the furnace, the obtained material was subjected to jaw crushing, roller crushing, airflow crushing and 325-mesh sieving to obtain sintered material.

[0112] (3) The sintering material obtained in step (2) and cobalt hydroxide are mixed evenly at a molar ratio of 1:0.01, and calcined at 660°C for 6 hours in a box furnace with 99 vol% O2 atmosphere. After cooling and sieving through a 325 mesh, high entropy doped cathode material is obtained.

[0113] Example 2

[0114] In this embodiment, the boron source is B2O3, the doping sources are ZrO2, Sb2O3, WO3, Nb2O5, and Al2O3, the lithium source is LiOH·H2O, and the nickel-cobalt-manganese precursor is Ni. 0.96 Co 0.03 Mn 0.01 The Dv50 of the (OH)2, nickel-cobalt-manganese precursor is 2 μm to 3 μm. The prepared high-entropy doped cathode material has a Dv50 of 2 μm to 3 μm and a specific surface area of ​​1.005 m². 2 / g.

[0115] Preparation methods of high-entropy doped cathode materials:

[0116] (1) Weigh Ni in a molar ratio of 1:1.04:0.05:0.01:0.005:0.01:0.005:0.005. 0.93 Co 0.05 Mn 0.02 The compounds (OH)2, LiOH·H2O, B2O3, ZrO2, Sb2O3, WO3, Nb2O5 and Al2O3 were mixed in an air jet mixer at a speed of 1200 rpm / min for 40 min to obtain a mixed raw material.

[0117] (2) The mixed raw materials are transferred to an atmosphere furnace for high-temperature sintering in a sintering atmosphere. First, the temperature is raised to 630℃ at a heating rate of 2.5℃ / min and calcined for 6 hours. Then, the temperature is raised to 725℃ at a heating rate of 2.5℃ / min and calcined for 16 hours. The oxygen content in the sintering atmosphere is 99 vol%. After cooling in the furnace, the obtained material is subjected to jaw crushing, roller crushing, airflow crushing and 325 mesh sieving in sequence to obtain sintered material.

[0118] (3) The sintering material obtained in step (2) and cobalt hydroxide are mixed evenly at a molar ratio of 1:0.01, and calcined at 660°C for 6 hours in a box furnace with 99 vol% O2 atmosphere. After cooling and sieving through a 325 mesh, high entropy doped cathode material is obtained.

[0119] Example 3

[0120] In this embodiment, the boron source is H3BO3, the doping sources are ZrO2, SrCO3, Ta2O5, Nb2O5, and CaO, the lithium source is LiOH·H2O, and the nickel-cobalt-manganese precursor is Ni. 0.96 Co 0.03 Mn 0.01 The Dv50 of the (OH)2, nickel-cobalt-manganese precursor is 2 μm to 3 μm. The prepared high-entropy doped cathode material has a Dv50 of 2 μm to 3 μm and a specific surface area of ​​1.023 m². 2 / g.

[0121] Preparation methods of high-entropy doped cathode materials:

[0122] (1) Weigh Ni in a molar ratio of 1:1.04:0.04:0.01:0.01:0.005:0.005:0.01. 0.93 Co 0.05 Mn 0.02 The compounds (OH)2, LiOH·H2O, H3BO3, ZrO2, SrCO3, Ta2O5, Nb2O5 and CaO were mixed in an air jet mixer at a speed of 1200 rpm / min for 40 min to obtain a mixed raw material.

[0123] (2) The mixed raw materials are transferred to an atmosphere furnace for high-temperature sintering in a sintering atmosphere. First, the temperature is raised to 630℃ at a heating rate of 2.5℃ / min and calcined for 6 hours. Then, the temperature is raised to 720℃ at a heating rate of 2.5℃ / min and calcined for 16 hours. The oxygen content in the sintering atmosphere is 99 vol%. After cooling in the furnace, the obtained material is subjected to jaw crushing, roller crushing, airflow crushing and 325 mesh sieving in sequence to obtain sintered material.

[0124] (3) The sintering material obtained in step (2) and cobalt hydroxide are mixed evenly at a molar ratio of 1:0.01. The mixture is then heat-treated at 660°C for 6 hours in a box furnace with a 99 vol%% O2 atmosphere. After cooling and sieving through a 325-mesh sieve, a high-entropy doped cathode material is obtained.

[0125] Comparative Example 1

[0126] In this comparative example, the high-nickel cathode material was not doped in any way; the lithium source was LiOH·H2O; and the nickel-cobalt-manganese precursor was Ni. 0.96 Co0.03 Mn 0.01 The Dv50 of the (OH)2, nickel-cobalt-manganese precursor is 2 μm to 3 μm. The prepared cathode material has a Dv50 of 2 μm to 3 μm and a specific surface area of ​​0.997 m². 2 / g.

[0127] Preparation method of high-nickel cathode material:

[0128] (1) Weigh Ni in a molar ratio of 1:1.04 0.96 Co 0.03 Mn 0.01 (OH)2 and LiOH·H2O were mixed in an air jet mixer at a speed of 1200 rpm / min for 40 min to obtain a mixed raw material.

[0129] (2) The mixed raw materials are transferred to an atmosphere furnace for high-temperature sintering in a sintering atmosphere. First, the temperature is raised to 630℃ at a heating rate of 2.5℃ / min and calcined for 6 hours. Then, the temperature is raised to 720℃ at a heating rate of 2.5℃ / min and calcined for 16 hours. The oxygen content in the sintering atmosphere is 99 vol%. After cooling in the furnace, the obtained material is subjected to roller crushing, airflow crushing, ultracentrifugal grinding and crushing and 325 mesh sieving to obtain sintered material.

[0130] (3) The sintering material obtained in step (2) and cobalt hydroxide are mixed evenly at a molar ratio of 1:0.01. The mixture is calcined at 660°C for 6 hours in a box furnace with 99 vol% O2 atmosphere. After cooling and sieving through a 325-mesh sieve, a high-nickel cathode material is obtained.

[0131] Comparative Example 2

[0132] In this comparative example, the cathode material does not contain boron (B), the doping sources are ZrO2, SrCO3, and Al2O3, the lithium source is LiOH·H2O, and the nickel-cobalt-manganese precursor is Ni. 0.96 Co 0.03 Mn 0.01 The Dv50 of the (OH)2, nickel-cobalt-manganese precursor is 2 μm to 3 μm. The prepared cathode material has a Dv50 of 2 μm to 3 μm and a specific surface area of ​​0.9866 m². 2 / g.

[0133] Preparation methods of doped cathode materials:

[0134] (1) Weigh Ni in a molar ratio of 1:1.04:0.01:0.01:0.005. 0.96 Co 0.03 Mn 0.01(OH)2, LiOH·H2O, ZrO2, SrCO3 and Al2O3 were mixed in an air jet mixer at a speed of 1200 rpm / min for 40 min. After thorough mixing, a mixed raw material was obtained.

[0135] (2) The mixed raw materials are transferred to an atmosphere furnace for high-temperature sintering in a sintering atmosphere. First, the temperature is raised to 630℃ at a heating rate of 2.5℃ / min and calcined for 6 hours. Then, the temperature is raised to 720℃ at a heating rate of 2.5℃ / min and calcined for 16 hours. The oxygen content in the sintering atmosphere is 99 vol%. After cooling in the furnace, the obtained material is subjected to roller crushing, ultracentrifugal grinding and crushing and 325 mesh sieving to obtain sintered material.

[0136] (3) The sintering material obtained in step (2) and cobalt hydroxide are mixed evenly at a molar ratio of 1:0.01. The mixture is then heat-treated at 660°C for 6 hours in a box furnace with 99 vol% O2 atmosphere, cooled, and sieved through a 325-mesh screen to obtain the doped cathode material.

[0137] Comparative Example 3

[0138] In this comparative example, only boron (B) was doped into the cathode material, with H3BO3 as the boron source, LiOH·H2O as the lithium source, and Ni as the nickel-cobalt-manganese precursor. 0.96 Co 0.03 Mn 0.01 (OH)₂. The prepared cathode material has a Dv₅₀ of 2 μm to 3 μm and a specific surface area of ​​0.974 m². 2 / g.

[0139] Preparation methods of doped cathode materials:

[0140] (1) Weigh Ni in a molar ratio of 1:1.04:0.01 0.96 Co 0.03 Mn 0.01 (OH)2, LiOH·H2O and H3BO3 were mixed in an air jet mixer at a speed of 1200 rpm / min for 40 min. After thorough mixing, a mixed raw material was obtained.

[0141] (2) The mixed raw materials are transferred to an atmosphere furnace for high-temperature sintering in a sintering atmosphere. First, the temperature is raised to 630℃ at a heating rate of 2.5℃ / min and calcined for 6 hours. Then, the temperature is raised to 720℃ at a heating rate of 2.5℃ / min and calcined for 16 hours. The oxygen content in the sintering atmosphere is 99 vol%. After cooling in the furnace, the obtained material is subjected to roller crushing, ultracentrifugal grinding and crushing and 325 mesh sieving to obtain sintered material.

[0142] (3) The sintering material obtained in step (2) and cobalt hydroxide are mixed evenly at a molar ratio of 1:0.01. The mixture is then heat-treated at 660°C for 6 hours in a box furnace with 99 vol% O2 atmosphere, cooled, and sieved through a 325-mesh screen to obtain the doped cathode material.

[0143] The high-entropy doped cathode material prepared in Example 1 and the cathode material prepared in Comparative Example 1 were characterized by scanning electron microscopy (SEM). The SEM images at a magnification of 30k are shown in Figures 1 and 2, respectively. As can be seen from Figures 1 and 2, the samples prepared in Example 1 and Comparative Example 1 are both polycrystalline samples with small primary particles, and the Dv50 of the secondary particles is 2μm to 3μm. After high-entropy doping modification, the primary particles in the cathode material of Example 1 are thin strips with good uniformity in size. In Comparative Example 1, the primary particles are polyhedral, and the uniformity in size is significantly poor.

[0144] The positive electrode materials prepared in the various embodiments and comparative examples were used as positive electrode active materials for lithium-ion secondary batteries to form positive electrode sheets and assemble coin-type lithium-ion half-cells. The method for manufacturing coin-type lithium-ion half-cells is as follows: the prepared positive electrode material powder is mixed with acetylene black and polyvinylidene fluoride in a mass ratio of 90:5:5, and an appropriate amount of N-methylpyrrolidone is added as a dispersant; the mixture is then ground into a slurry. The slurry is then uniformly coated onto one side of an aluminum foil, vacuum dried at 120°C for 12 hours, and the dried electrode sheet is rolled using a roller press. The aluminum foil is then cut into circular electrode sheets with a diameter of 10 mm using a slicing machine, and the compaction density of the electrode sheets is 3.4 g / cm³. 3 The half-cells were assembled in an argon-atmospheric glove box with a water partial pressure ≤0.1ppm and an oxygen partial pressure ≤0.1ppm. A lithium metal sheet was used as the negative electrode, and a 1M LiPF6 (EC / DMC, volume ratio 1:1) solution was used as the electrolyte. The assembled cells were CR2032 type coin cells. Capacity testing employed a constant current / constant voltage charge-discharge mode, with a charge-discharge rate of 0.1C followed by 1 / 3C. Cycling was performed at 45℃ and a 0.5C rate. The capacity and cyclic test charge-discharge voltage ranges were both set to 2.5–4.3V. The test results are shown in Table 1 and Figure 3.

[0145] Table 1

[0146] The high-entropy doped cathode material in the embodiments of this application can simultaneously possess high specific capacity and cycle stability.

[0147] 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.

[0148] 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 invention patent. 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-entropy doped cathode material, characterized in that, LiNi x Co y Mn z B a M b O2, wherein 0.80≤x<0.98, 0 M comprises at least four of Al, Zr, Sr, Sn, Sb, Si, Ba, Y, W, Ta, Ti, Mo, Nb, La, Ta, and Ce.

2. The high-entropy doped cathode material of claim 1, wherein, 0.90≤x<0.98; and / or, 0.01≤a≤0.05; and / or, 0.01≤b≤0.05; and / or, 0.01≤y≤0.05; and / or, 0.01≤z≤0.

05.

3. The high-entropy doped cathode material of claim 1 or 2, wherein, Dv50 of the secondary particles of the high-entropy doped cathode material is 2-5 μm; and / or, The high-entropy doped positive electrode material has a specific surface area of 0.5 m 2 / g~1.5 m 2 / g.

4. A method for preparing a high-entropy doped cathode material, characterized in that, The method comprises the following steps: mixing a doping source, a boron source, a lithium source and a nickel-cobalt-manganese precursor to obtain a mixed raw material; sintering the mixed raw material; The doping source comprises at least four of Al, Zr, Sr, Sn, Sb, Si, Ba, Y, W, Ta, Ti, Mo, Nb, La, Ta and Ce; The nickel cobalt manganese precursor includes a material of a chemical formula of Ni m Co n Mn 1-m-n (OH)2, wherein 0.80≤m<0.98, n>0, and m+n<1.

5. The method of claim 4, wherein the high-entropy doped cathode material is prepared by the steps of: mixing a first metal oxide with a second metal oxide to form a mixture; and heating the mixture to form the high-entropy doped cathode material. The molar ratio of lithium in the lithium source to the nickel-cobalt-manganese precursor is (1.01-1.06):1; and / or, The boron element in the boron source accounts for 1%-5% of the mixed raw material in terms of mole percentage; and / or, The M element in the doping source accounts for 0.5%-5% of the mixed raw material in terms of mole percentage; and / or, The boron source comprises at least one of H3BO3 and B2O3; and / or, The doping source comprises at least one of the oxides, carbonates, hydroxides and acetates of M; and / or, The lithium source comprises at least one of lithium hydroxide, lithium carbonate, lithium acetate, lithium nitrate and lithium oxalate.

6. The method for preparing the high-entropy doped cathode material according to claim 4 or 5, characterized in that, The sintering of the mixed raw material comprises the following steps: pre-sintering the mixed raw material in an oxygen-containing gas atmosphere; continuing the first sintering of the mixed raw material after the temperature rising to obtain a sintered material; mixing the sintered material and cobalt hydroxide and then second sintering in an oxygen-containing gas atmosphere.

7. The method of claim 6, wherein the high-entropy doped cathode material is prepared by the steps of: mixing a first metal oxide with a second metal oxide to form a mixture; and heating the mixture to form the high-entropy doped cathode material. The temperature of the pre-sintering is 450-650℃; and / or, The time of the pre-sintering is 2-10 h; and / or, The temperature of the first sintering is 700-900℃; and / or, The time of the first sintering is 10-20 h; and / or, The temperature of the second sintering is 580-680℃; and / or, The time of the second sintering is 2-10 h; and / or, The volume percentage of oxygen in the oxygen-containing gas is above 97%.

8. A positive electrode sheet characterized by comprising: It comprises: a current collector and an active layer on the surface of the current collector, wherein the active layer comprises the high-entropy doped cathode material of any one of claims 1-3 or the high-entropy doped cathode material prepared by the method of any one of claims 4-7.

9. A secondary battery characterized by comprising: It comprises the cathode sheet of claim 8.

10. An electrical device, characterized by It comprises the secondary battery of claim 9.

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