High-nickel positive electrode material, preparation method thereof and lithium-ion battery

Abstract

The present disclosure relates to a high-nickel cathode material, a method for preparing the same, and a lithium-ion battery. The general formula of the high-nickel cathode material is the following formula (1): Li x Ni 1-(a+b+c+d+e+f) Co a M1 b M2 c M3 d M4 e M5 f O2(1), provided that 0.95 ≤ x ≤ 1.2, 0 ≤ a ≤ 0.15, 0 ≤ b ≤ 0.10, 0 ≤ c ≤ 0.05, 0 ≤ d ≤ 0.05, 0 ≤ e ≤ 0.05, 0 ≤ f ≤ 0.05, and 0 < a + b + c + d + e + f ≤ 0.2 are satisfied. On the surface of the high-nickel material according to the present disclosure, the amount of Ni 3+ is relatively small and the amount of Ni 2+ is relatively large, which can prevent the surface of the cathode material from being oxidized when lithium ions are desorbed, contribute to maintaining the structural stability of the cathode material, prevent the loss of the cathode active material and the electrolyte, further increase the capacity of the cathode material, and significantly improve the high-temperature cycle performance of the high-nickel cathode material.

Description

[Technical Field]

[0001] The present disclosure relates to the technical field of cathode materials, and in particular to high-nickel cathode materials, their preparation methods, and lithium-ion batteries.

[0002] Cross-reference to related applications This disclosure claims priority to a Chinese application filed with the China Patent Office on December 8, 2021, bearing application number CN202111491138.2 and entitled "High-nickel positive electrode material, its preparation method and lithium-ion battery," the entire contents of which are incorporated herein by reference. [Background technology]

[0003] Lithium-ion batteries, with their high energy density, excellent safety performance, long cycle life, and environmental friendliness, are widely used in fields such as laptops, mobile phones, and digital products. With growing environmental awareness, lithium-ion batteries are also being used as power batteries in transportation, including electric vehicles (e.g., electric buses). Market demands for lithium-ion batteries, particularly their specific capacity, energy density, power density, and service life, are increasing. The most widely used cathode materials in lithium-ion batteries are primarily olivine-structured LiFePO4, layered-structured LiCoO2, and layered-structured lithium-nickel-based oxides. Olivine-structured LiFePO4 has reached its capacity limit and is expected to be used primarily in energy storage and short-range electric vehicles. Layered-structured LiCoO2 is primarily used in consumer batteries. Lithium-nickel-based oxides are widely used in electric vehicles. In lithium nickel-based oxide materials, nickel is the main element involved in the redox reaction, so increasing the nickel content can effectively increase the specific capacity of such materials. Therefore, the development of high-nickel materials has become a priority in the market.

[0004] Currently, the main factors limiting the application range of high-nickel ternary materials in power batteries are their poor high-temperature performance, rapid increase in direct current internal resistance (DCR), and gas generation. These disadvantages are mainly due to the following three reasons. First, the inherent structure of high-nickel ternary materials changes irreversibly as charging and discharging progresses, and the higher the nickel content, the greater the structural change. During charging and discharging, the oxidation number of nickel in high-nickel materials changes corresponding to the desorption and insertion of lithium ions. At the same voltage, the higher the nickel content, the more lithium ions are desorbed, resulting in a greater change in the volume of the material. This volume change is accompanied by the release of internal stress in the material, which can lead to cracks in the high-nickel material. In particular, in the case of high-nickel materials in a charged state, the electrolyte can enter the material through the cracks and dissolve the highly active Ni 4+ Secondly, when lithium ions are released from high-nickel ternary materials, the Ni on the surface of the material undergoes a redox reaction, resulting in a structural change of the material. 3+ Strongly oxidizing Ni 4+ converted to Ni 4+ However, because the organic electrolyte reacts easily with the cathode active material, this leads to a loss of the cathode active material and electrolyte, a decrease in capacity, an increase in DC internal resistance, and gas generation. Thirdly, alkaline impurities (including Li2CO3 and LiOH that remain on the surface of the material) are easily generated during the synthesis of high-nickel ternary materials. These alkaline impurities are not conductive and easily react with the electrolyte, leading to gas generation and polarization in the battery.

[0005] In view of the above, there is an urgent need to develop high-nickel positive electrode materials that can solve the problems of poor high-temperature performance, rapid increase in DC internal resistance, and gas generation, so that high-nickel ternary materials can be more widely used in power batteries. Summary of the Invention

[0006] The present disclosure provides a high-nickel positive electrode material, the general formula of which is the following formula (1): Li x Ni1-(a+b+c+d+e+f) Co a M1 b M2 c M3 d M4 e M5 f O2(1) However, 0.95 ≦ x ≦ 1.2, 0 ≦ a ≦ 0.15, 0 ≦ b ≦ 0.10, 0 ≦ c ≦ 0.05, 0 ≦ d ≦ 0.05, 0 ≦ e ≦ 0.05, 0 ≦ f ≦ 0.05, and 0 < a + b + c + d + e + f ≦ 0.2 are satisfied. XPS measurement of the powder sample is performed on the high-nickel cathode material using AlKα rays, and Ni2P appears within the range where the binding energy is 850 eV to 870 eV. 3 / 2 After performing peak separation and fitting on the peak, the peak area of Ni 2+ is set as S1, the peak area of Ni 3+ is set as S2, the full width at half maximum of the peak of Ni 2+ is set as α, and the full width at half maximum of the peak of Ni 3+ is set as β. Then, S1, S2, α, and β satisfy S1 / (S1 + S2)>0.5 and 0.9 < α / β < 1.5 (2) and satisfy the relationship.

[0007] Optionally, the high-nickel cathode material includes at least one of secondary particles and primary particles, at least a part of the surface of the primary particles is coated with a coating layer, and the secondary particles include a plurality of primary particles having a coating layer.

[0008] Optionally, the coating layer includes a first coating layer and a second coating layer. The first coating layer is formed on the surface of the primary particles, and the second coating layer is formed on the surface of the first coating layer.

[0009] Optionally, the coating layer includes a first coating layer, and the first coating layer is formed on the surface of the primary particles.

[0010] Optionally, the coating layer includes a second coating layer, and the second coating layer is formed on the surface of the primary particles.

[0011] Optionally, the coating layer comprises a first coating layer and a second coating layer, and the first coating layer comprises an element in the high-nickel positive electrode material that has an oxidation number of +3 or more.

[0012] Optionally, the coating layer comprises a first coating layer and a second coating layer, and the first coating layer comprises at least one of Al, Ti, P, Si, Nb, Y, W, Cr, Zr, and La.

[0013] Optionally, the coating layer comprises a first coating layer and a second coating layer, and the first coating layer comprises a compound containing at least one of Al, Ti, P, Si, Nb, Y, W, Cr, Zr, and La.

[0014] Optionally, the coating layer comprises a first coating layer and a second coating layer, and the first coating layer comprises a compound containing at least one of Al, Ti, P, Si, Nb, Y, W, Cr, Zr, and La, and the compound is at least one of an oxide, a hydroxide, and a salt.

[0015] Optionally, the coating layer comprises a first coating layer and a second coating layer, and the second coating layer comprises a compound containing at least one of B, La, and Al.

[0016] Optionally, the coating layer includes a first coating layer and a second coating layer, and the second coating layer includes a compound containing at least one of B, La, and Al, and the compound includes at least one of an oxide, an acid, and a lithium-containing salt.

[0017] Optionally, the coating layer comprises a first coating layer and a second coating layer, the second coating layer comprising a boron-containing compound.

[0018] Optionally, the coating layer includes a first coating layer and a second coating layer, and the second coating layer includes a boron-containing compound, and the boron-containing compound includes at least one of a boron-containing oxide, a boron-containing acid, and a salt containing boron and lithium.

[0019] Optionally, the coating layer comprises a first coating layer and a second coating layer, the second coating layer comprising a boron-containing compound, the boron-containing compound being selected from the group consisting of B2O3, H3BO3, Li2O-B2O3, Li3BO3, Li2BO7, Li2BO7, and Li2BO. 13 It contains at least one of the following.

[0020] Optionally, said M1 comprises at least one of Mn and Al.

[0021] Optionally, said M2 comprises an element having an oxidation number of +4 or greater in said high nickel positive electrode material.

[0022] Optionally, said M3 comprises an element having an oxidation number of +2 in said high nickel positive electrode material.

[0023] Optionally, each of M2 and M3 comprises at least one of Zr, Ti, Nb, Ce, Hf, W, Mo, Ta, Ge, Sn, Sr, Mg, and Ba, and M2 and M3 are different.

[0024] Optionally, said M4 comprises an element having an oxidation number of +3 or greater in said high nickel positive electrode material.

[0025] Optionally, said M4 comprises at least one of Al, Ti, P, Si, Nb, Y, W, Cr, Zr and La.

[0026] Optionally, said M5 comprises at least one of B, La and Al.

[0027] Optionally, said M5 comprises B.

[0028] Optionally, XPS measurement of a powder sample of the high-nickel positive electrode material is performed using AlKα radiation, and NiP appears in the binding energy range of 850 eV to 870 eV. 3 / 2 After peak separation and fitting, Ni 2+ / Ni 3+ The area ratio is greater than 1.

[0029] Optionally, XPS measurement of a powder sample of the high-nickel positive electrode material is performed using AlKα radiation. Peak separation and fitting are performed on the O1S peaks that appear in the binding energy range of 526 eV to 540 eV, and the O1S 格子酸素 / O1S 不純物酸素 The area ratio is more than 1 / 2.

[0030] Optionally, the mass fraction of LiOH in the high nickel positive electrode material is less than 0.3 wt %.

[0031] Optionally, the mass fraction of Li2CO3 in the high nickel positive electrode material is less than 0.3 wt%.

[0032] Optionally, the crystalline structure of the high nickel positive electrode material is a hexagonal or monoclinic crystalline structure.

[0033] Optionally, the morphology of the crystal particles of the high-nickel positive electrode material includes at least one of substantially spherical, substantially cubic, and substantially rectangular.

[0034] Optionally, the pH of the high nickel positive electrode material is 10 <pH<12である。

[0035] Optionally, the high nickel positive electrode material has a pH of 10.5 <pH<11.7である。

[0036] Optionally, the powder conductivity of the high nickel positive electrode material is greater than 0.02 S / cm.

[0037] Optionally, the high nickel positive electrode material has a specific surface area of ​​0.3 m 2 / g~0.8m 2 / g.

[0038] Optionally, the high nickel positive electrode material has an average particle size of 2.5 μm to 4.5 μm.

[0039] The present disclosure further discloses a method for preparing a high-nickel positive electrode material, the method comprising: A step of mixing a metal composite hydroxide precursor, a lithium-containing compound, and a dopant, and subjecting the mixture to a primary heat treatment to obtain a substrate material; and applying a coating to the substrate material to obtain a high-nickel positive electrode material; The dopant includes a compound containing an M2 element and a compound containing an M3 element, and the compound containing the M2 element is at least one of an oxide, hydroxide, and lithium metal oxide containing only M2, and in the compound, the oxidation number of M2 is +4 or more, and the compound containing the M3 element is at least one of an oxide and hydroxide containing only M3, and in the compound, the oxidation number of M3 is +2.

[0040] Optionally, the mass ratio of the metal composite hydroxide precursor to the lithium-containing compound to the dopant is 1:(0.46-0.49):(0.001-0.005).

[0041] Optionally, the mass ratio of the metal composite hydroxide precursor to the lithium-containing compound to the dopant is 1:(0.46-0.48):(0.001-0.003).

[0042] Optionally, the atomic ratio of the total number of metal atoms Me in the metal composite hydroxide precursor to the number of Li atoms in the lithium-containing compound is 1.0 <Li / Me<1.2である。

[0043] Optionally, the lithium-containing compound comprises a lithium-containing salt and a lithium-containing hydroxide.

[0044] Optionally, the lithium-containing compound comprises at least one of lithium carbonate, lithium hydroxide, lithium nitrate, and lithium acetate.

[0045] Optionally, each of the M2 and M3 elements is at least one selected from Zr, Ti, Nb, Ce, Hf, W, Mo, Ta, Ge, Sn, Sr, Mg, and Ba, and M2 and M3 are different.

[0046] Optionally, the molar ratio n of M2 to M3 M2 :n M3 is 2:1 or greater.

[0047] Optionally, the average particle size of the dopant is between 10 nm and 50 nm.

[0048] Optionally, the temperature of the primary heat treatment is 680°C to 900°C.

[0049] Optionally, the duration of the primary heat treatment is 5 hours to 20 hours.

[0050] Optionally, the temperature rise rate of the primary heat treatment is 50°C / h to 550°C / h.

[0051] Optionally, the oxygen content in the substrate material is 85% or greater.

[0052] Optionally, the method includes the step of mixing the substrate material with a first coating and subjecting the mixture to a secondary heat treatment to obtain a primary coating product.

[0053] Optionally, in the method, the mass ratio of the substrate material to the first coating agent is 1000:(0.5-3).

[0054] Optionally, in the method, the first coating agent comprises a metal element or a non-metal element having an oxidation number of +3 or greater.

[0055] Optionally, in the method, the first coating agent comprises at least one of an oxide, a salt, or a hydroxide of a metal element or a non-metal element having an oxidation number of +3 or higher.

[0056] Optionally, in the method, the first coating agent comprises a metal element or a non-metal element having an oxidation state of +3 or greater, and the metal element or non-metal element comprises at least one of Al, Ti, P, Si, Nb, Y, W, Cr, Zr, or La.

[0057] Optionally, in the method, the first coating comprises at least one of lithium aluminate, lithium titanate, lithium lanthanum titanate, yttrium oxide, aluminum oxide, and titanium oxide.

[0058] Optionally, in the method, the first coating agent has an average particle size of 10 nm to 50 nm.

[0059] Optionally, in the method, the temperature of the secondary heat treatment is 600°C to 800°C.

[0060] Optionally, in the method, the duration of the secondary heat treatment is 1 hour to 20 hours.

[0061] Optionally, in the method, the temperature increase rate of the secondary heat treatment is 50°C / h to 550°C / h.

[0062] Optionally, the method further comprises the steps of washing under isothermal conditions after the secondary heat treatment, and then drying under vacuum conditions after washing, wherein the temperature of the isothermal conditions is 10°C to 25°C.

[0063] Optionally, the method further comprises the steps of washing under a constant temperature condition after the secondary heat treatment, and then drying under a vacuum condition after washing, wherein the temperature of the drying treatment is 100°C to 200°C.

[0064] Optionally, in the method, the oxygen content in the primary coating product is 85% or greater.

[0065] Optionally, the method further comprises the step of mixing the primary coating product with a second coating agent and subjecting the mixture to a tertiary heat treatment.

[0066] Optionally, in the method, the second coating comprises a compound containing at least one of B, La, and Al.

[0067] Optionally, in the method, the second coating agent comprises a compound containing at least one of B, La, and Al, the compound being an oxide, an acid, or a lithium-containing salt.

[0068] Optionally, in the method, the second coating comprises a boron-containing compound.

[0069] Optionally, in the method, the second coating agent comprises a boron-containing compound, the boron-containing compound comprising a boron-containing oxide, a boron-containing acid, or a salt containing boron and lithium.

[0070] Optionally, in the method, the second coating agent comprises a boron-containing compound, the boron-containing compound being selected from the group consisting of B2O3, H3BO3, Li2O-B2O3, Li3BO3, Li2BO7, Li2BO7, and Li2BO 13 It contains at least one of the following.

[0071] Optionally, in the method, the mass ratio of the primary coating product to the second coating agent is 1:(0.0005-0.005).

[0072] Optionally, in the method, the temperature of the tertiary heat treatment is 200°C to 600°C.

[0073] Optionally, in the method, the duration of the tertiary heat treatment is 1 hour to 20 hours.

[0074] Optionally, in the method, the temperature rise rate of the tertiary heat treatment is 50° C. / h to 550° C. / h.

[0075] Optionally, the metal composite hydroxide precursor is obtained by subjecting a metal salt solution, a complexing agent, and a pH adjuster to a mixing treatment.

[0076] Optionally, in the method, the mass ratio of the metal salt solution to the complexing agent to the pH adjuster is 1:(0.01-0.10):(0.1-0.8).

[0077] Optionally, in the method, the metal salt solution comprises at least one of a nickel salt solution, a cobalt salt solution, a manganese salt solution, and an aluminum salt solution.

[0078] Optionally, in the method, the complexing agent comprises at least one of aqueous ammonia, ammonium sulfate, ammonium chloride, ammonium carbonate, ammonium fluoride, hydrazine, ethylenediaminetetraacetic acid, nitrilotriacetic acid, uracildiacetic acid, and glycine.

[0079] Optionally, in the method, the pH adjuster comprises at least one of sodium hydroxide and potassium hydroxide.

[0080] Optionally, in the method, the pH of the mixing treatment is 9-13.

[0081] Optionally, in the method, the temperature of the mixing treatment is 10°C to 80°C.

[0082] Optionally, in the method, the mixing time is from 10 hours to 200 hours.

[0083] Optionally, in the method, the mixing treatment is carried out under stirring, and the stirring speed is 800 rpm to 1200 rpm.

[0084] Optionally, the method includes the steps of solid-liquid separation, washing and drying after the mixing treatment.

[0085] Optionally, in the method, the metal composite hydroxide precursor has an average particle size of 3 μm to 10 μm.

[0086] The present disclosure further discloses a lithium-ion battery comprising the high-nickel positive electrode material described above or prepared by the method described above.

[0087] In order to more clearly describe the technical solutions of the embodiments of the present disclosure or the prior art, the drawings necessary for describing the embodiments or the prior art will be briefly described below. The drawings described are merely some embodiments of the present disclosure. Those skilled in the art can derive other drawings based on these drawings without using inventive abilities. Furthermore, the drawings merely exemplify embodiments of the present disclosure, and the objects shown in the drawings are not necessarily drawn in proportion to the embodiments. The drawings merely illustrate some embodiments of the present disclosure and are not intended to limit the scope. [Brief explanation of the drawings]

[0088] [Figure 1] 1 is a flowchart illustrating a process for preparing a high-nickel positive electrode material according to some embodiments of the present disclosure. [Figure 2] 1 is an SEM photograph of a high-nickel cathode material according to some embodiments of the present disclosure. [Figure 3] 1 is a graph obtained by performing peak separation and curve fitting on the peak Ni2P3 / 2 of the Ni bonding portion in the binding energy range of 850 eV to 870 eV for the high-nickel positive electrode material according to Example 1 of the present disclosure. [Figure 4] 10 is a graph obtained by performing peak separation and curve fitting on the peak Ni2P3 / 2 of the Ni bonding portion in the binding energy range of 850 eV to 870 eV for the high-nickel positive electrode material according to Example 8 of the present disclosure. [Figure 5] 1 is a graph obtained by performing peak separation and curve fitting on the peak Ni2P3 / 2 of the Ni bonding portion in the bond energy range of 850 eV to 870 eV for the high-nickel positive electrode material according to Comparative Example 1. [Figure 6] 1 is a graph obtained by performing peak separation and curve fitting on the peak Ni2P3 / 2 of the Ni bonding portion in the bond energy range of 850 eV to 870 eV for the high-nickel positive electrode material according to Comparative Example 2. [Figure 7]1 is a graph obtained by performing peak separation and curve fitting on the peak O1S of the O bond portion in the bond energy range of 526 eV to 540 eV for the high-nickel positive electrode material according to Example 1 of the present disclosure. [Figure 8] 10 is a graph obtained by performing peak separation and curve fitting on the peak O1S of the O bond portion in the binding energy range of 526 eV to 540 eV for the high-nickel positive electrode material according to Example 8 of the present disclosure. [Figure 9] 1 is a graph obtained by performing peak separation and curve fitting on the peak O1S of the O bond portion in the bond energy range of 526 eV to 540 eV for the high-nickel positive electrode material according to Comparative Example 1. [Figure 10] 1 is a graph obtained by performing peak separation and curve fitting on the peak O1S of the O bond portion in the bond energy range of 526 eV to 540 eV for the high-nickel positive electrode material of Comparative Example 2. [Figure 11] 1 is a graph showing the differential capacity curve of a high-nickel positive electrode material according to Example 1 of the present disclosure. [Figure 12] 10 is a graph showing the differential capacity curve of a high-nickel positive electrode material according to Example 8 of the present disclosure. [Figure 13] 1 is a graph showing a differential capacity curve of a high-nickel positive electrode material according to Comparative Example 1. [Figure 14] 1 is a graph showing a differential capacity curve of a high-nickel positive electrode material according to Comparative Example 2. [Figure 15] 1 is an SEM photograph of high-nickel cathode material according to Example 1 of the present disclosure processed by a cross-section polisher after 300 cycles. [Figure 16] 10 is an SEM photograph of high nickel positive electrode material according to Example 8 of the present disclosure processed by a cross-section polisher after 300 cycles. [Figure 17] 1 is an SEM photograph of the high-nickel positive electrode material according to Comparative Example 1, which was processed with a cross-section polisher after 300 cycles. [Figure 18] 1 is an SEM photograph of the high-nickel positive electrode material according to Comparative Example 2, which was processed with a cross-section polisher after 300 cycles. [Figure 19] 10 is an SEM photograph of high nickel cathode material according to Example 25 of the present disclosure after 300 cycles processed by a cross section polisher. [Figure 20] 10 is an SEM photograph of high nickel cathode material according to Example 26 of the present disclosure processed by a cross-section polisher after 300 cycles. [Figure 21] 10 is an SEM photograph of a high-nickel positive electrode material according to Comparative Example 6 of the present disclosure, processed by a cross-section polisher after 300 cycles. [Figure 22] FIG. 1 is a schematic diagram showing a partial cross-section of a high-nickel positive electrode material according to some embodiments of the present disclosure. [Figure 23] FIG. 1 is a schematic diagram showing a partial cross-section of a high-nickel positive electrode material according to some embodiments of the present disclosure. [Figure 24] FIG. 1 is a schematic diagram showing a partial cross-section of a high-nickel positive electrode material according to some embodiments of the present disclosure. [Figure 25] FIG. 1 is a schematic diagram showing a partial cross-section of a high-nickel positive electrode material according to some embodiments of the present disclosure. [Figure 26] 22-26 are schematic diagrams showing partial cross sections of high-nickel positive electrode materials according to some embodiments of the present disclosure. Note that the rectangular boundaries in Figures 22-26 are merely illustrative illustrations of cross sections of portions (viewed from any angle) of the high-nickel positive electrode materials. DETAILED DESCRIPTION OF THE INVENTION

[0089] In order to better understand the technical solution of the present disclosure, the following detailed description of embodiments and examples of the present disclosure will be given with reference to the drawings.

[0090] The described embodiments and examples are only some of the embodiments and examples of the present disclosure, and are not all of the embodiments and examples. All other embodiments and examples that a person skilled in the art can obtain based on the embodiments and examples of the present disclosure without using his or her inventive ability also fall within the scope of protection of the present disclosure.

[0091] Additionally, the terms "first" and "second" are for descriptive purposes only and do not express or imply relative importance or quantity of technical features, so that features qualified by "first" and "second" may express or imply the inclusion of one or more of said features.

[0092] To facilitate understanding of the present disclosure, certain terms are defined appropriately in this disclosure. Unless otherwise defined herein, scientific and technical terms used in this disclosure have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0093] The term "substrate" as used herein refers to a lithium-based composite oxide synthesized by mixing a precursor and a lithium salt and subjecting them to a high-temperature solid-state reaction, and contains lithium and a metal element.

[0094] As used herein, the term "primary particles" refers to particles that exist alone and are not formed into aggregates.

[0095] The term "secondary particles" as used herein refers to particles formed by agglomeration of the above primary particles.

[0096] Ternary cathode materials (NCMs) consist of LiCoO2 and LiNi 0.5 Mn 0.5 It can be understood as a solid solution of O2 and LiNiO2, and its general formula is Li 1+a [Ni z (Ni 1 / 2 Mn 1 / 2 ) y C Ox ] 1-a O2. Z is Ni 3+For example, LiNi 0.6 Co 0.2 Mn 0.2 O2 is 0.2LiCoO2 + 0.4LiNi 0.5 Mn 0.5 O2 + 0.4LiNiO2, and therefore Ni 3+ The ratio of LiNi to LiNi is 0.4. 0.885 Co 0.09 Mn 0.025 Ni in O 3+ The ratio of LiNi is 0.86. 0.8 Co 0.15 Al 0.05 Ni in O 3+ The ratio of Ni is 0.8. 3+ The amount of oxygen required for synthesis is also high because the ratio of Ni in the precursor is high. 2+ Ni 3+ For example, LiNi 0.885 Co 0.09 Mn 0.025 O2 and LiNi 0.8 Co 0.15 Al 0.05 O2 can only be synthesized in a high oxygen concentration atmosphere. 0.4 Co 0.2 Mn 0.4 O2 is Ni 3+ Since the ratio of 0, it can be synthesized in an air atmosphere, and the alkaline impurities on its surface are very small. The synthesized high nickel material is very sensitive to moisture in the air, which is the main reason for the Ni content in the high nickel material. 3+ This is because the ratio of is relatively high, so it is easy for the lithium in the high nickel material to undergo a proton exchange reaction with water in the air to produce LiOH. 3+ In the case of medium- and low-nickel materials with a low ratio of Ni, the proton exchange reaction is difficult to occur. Therefore, the production and storage of high-nickel materials must be in a low-humidity environment. After the battery is charged, the Ni in the material 3+ Ni4+ is converted to Ni with strong oxidizing properties 4+ and the Ni that comes into direct contact with the electrolyte 4+ + electrolyte → Ni 2+ undergoes a redox reaction with {H2O, CO2}, generating gas that causes the battery to expand, and the sudden and significant decrease in battery capacity due to the loss of the positive electrode active material. The high-nickel material has a high ratio of Ni 3+ and since the surface layer (5 nm to 10 nm) of the high-nickel material is the part where Ni 3+ comes into direct contact with the electrolyte or air, how to appropriately control the ratio of Ni 3+ in the surface layer of the high-nickel material is important for improving the high-temperature cycle performance of the high-nickel material, reducing gas generation in the material, reducing alkaline impurities on the material surface, and suppressing the increase in DC internal resistance, etc.

[0097] Therefore, the present disclosure provides a high-nickel positive electrode material, a method for preparing the same, and a lithium-ion battery. The high-nickel positive electrode material according to the present disclosure has a relatively small amount of Ni 3+ on the surface and a relatively large amount of Ni 2+ and can prevent the surface of the high-nickel positive electrode material from being oxidized when lithium ions are desorbed, thereby improving the high-temperature cycle performance and structural stability of the high-nickel positive electrode material.

[0098] I. Positive Electrode Material One embodiment of the present disclosure provides a high-nickel positive electrode material. The general formula of the positive electrode material is the following formula (1). Li x Ni 1-(a+b+c+d+e+f) Co a M1 b M2 c M3 d M4 e M5 f O2(1) However, 0.95 ≦ x ≦ 1.2, 0 ≦ a ≦ 0.15, 0 ≦ b ≦ 0.10, 0 ≦ c ≦ 0.05, 0 ≦ d ≦ 0.05, 0 ≦ e ≦ 0.05, 0 ≦ f ≦ 0.05, 0 < a + b + c + d + e + f ≦ 0.2 are satisfied.

[0099] XPS measurement of powder samples of high-nickel positive electrode materials was performed using AlKα radiation. Ni2P appears in the binding energy range of 850 eV to 870 eV. 3 / 2 After peak separation and fitting, Ni 2+ The peak area of ​​Ni is S1. 3+ The peak area of ​​Ni is S2. 2+ The half-width of the peak is represented by α (or a, where a is different from a in the general formula above), and Ni 3+ is expressed as β (or b, where b is different from b in the general formula above), S1, S2, α(a) and β(b) satisfy the following relationship:

[0100] S1 / (S1+S2)>0.5 and 0.9<α / β<1.5(S1 / (S1+S2)>0.5 and 0.9

[0101] In the above technical solution, XPS measurement shows that the high-nickel positive electrode material of the present disclosure satisfies the relationship S1 / (S1+S2)>0.5 and 0.9<α / β<1.5, which indicates that the surface of the high-nickel positive electrode material of the present disclosure is covered with Ni. 3+ The amount of Ni is relatively small. 2+ The relatively large amount of Ni can prevent the surface of the high-nickel positive electrode material from being oxidized during the desorption of lithium ions, contribute to maintaining the stability of the structure of the positive electrode material, prevent the loss of the positive electrode active material and electrolyte during the charge and discharge process, further increase the capacity of the positive electrode material, and significantly improve the high-temperature cycle performance of the high-nickel positive electrode material. 3+ The amount of Ni is relatively small. 2+ Since the amount of is relatively large, it is possible to suppress the occurrence of cracks inside the material during the charge and discharge process and to stabilize the internal structure of the material. As a result, when the positive electrode material according to the present disclosure is used in a battery, the increase in the DC internal resistance of the battery during long-term cycles is significantly suppressed. ​

[0102] (1) Structure of the positive electrode material In some embodiments, the positive electrode material 100 includes particles 120 and a coating layer 140 formed on the surface of the particles 120 .

[0103] In some embodiments, particles 120 include at least one of secondary particles 124 and primary particles 122. At least a portion of the surface of primary particles 122 is coated with coating layer 140, and secondary particles 124 include a plurality of primary particles 122 having coating layer 140.

[0104] In some embodiments, the positive electrode material 100 includes at least one of secondary particles 124 and primary particles 122, at least a portion of the surface of the primary particles 122 being coated with a coating layer 140, and the secondary particles 124 including a plurality of primary particles 122 having the coating layer 140. The secondary particles 124 are aggregates of a plurality of primary particles 122. The positive electrode material 100 according to the present disclosure may include only primary particles 122, only secondary particles 124, or a mixture of the primary particles 122 and the secondary particles 124.

[0105] In some embodiments, as shown in Figure 22, the coating layer 140 includes a first coating layer 142 and a second coating layer 144, where the first coating layer 142 is formed on the surface of the primary particles 122 and the second coating layer 144 is formed on the surface of the first coating layer 142. In some embodiments, as shown in Figure 25, only the first coating layer 142 is formed on the surface of the primary particles 122. In some embodiments, as shown in Figure 26, only the second coating layer 144 is formed on the surface of the primary particles 122. The first coating layer 142 can improve the stability of the surface structure of the material, and the second coating layer 144 can effectively improve the processing performance and conductive performance of the material.

[0106] 23 , in some embodiments, the cathode material 100 includes primary particles 122, secondary particles 124, and a coating layer 140. The coating layer includes a first coating layer 142 and a second coating layer 144. The first coating layer 142 is formed on the surface of the primary particles 122. The second coating layer 144 is formed on the surface of the first coating layer 142. The secondary particles include a plurality of primary particles 122 having the coating layer 140.

[0107] In some embodiments, the positive electrode material 100 includes secondary particles 124. The secondary particles 124 include a plurality of primary particles 122, and the surfaces of the primary particles 122 are coated with a coating layer 140.

[0108] 24 , in some embodiments, the positive electrode material 100 includes secondary particles 124. The secondary particles 124 include a plurality of primary particles 122. The surfaces of the primary particles 122 are coated with a coating layer 140. The coating layer 140 includes a first coating layer 142 and a second coating layer 144. The first coating layer 142 is formed on the surfaces of the primary particles 122. The second coating layer 144 is formed on the surfaces of the first coating layer 142.

[0109] (2) Components of the positive electrode material In some embodiments, the first coating layer 142 includes an element that has an oxidation number of +3 or greater in the high-nickel positive electrode material 100 .

[0110] In some embodiments, the first coating layer 142 includes at least one of Al, Ti, P, Si, Nb, Y, W, Cr, Zr, and La. Since the oxidation number of the above elements is +3 or more in the high-nickel positive electrode material 100, the Ni in the surface layer of the high-nickel positive electrode material 100 2+ The amount of the cations in the positive electrode material 100 remains unchanged or even increases, thereby improving the structural stability of the positive electrode material 100 and suppressing the generation of alkaline impurities on the surface of the material. Note that the surface layer of the high-nickel positive electrode material 100 refers to the portion from the surface of the primary particles 122 to a thickness of 5 nm to 10 nm.

[0111] In some embodiments, the coating layer comprises a first coating layer and a second coating layer, and the first coating layer comprises a compound containing at least one of Al, Ti, P, Si, Nb, Y, W, Cr, Zr, and La.

[0112] In some embodiments, the coating layer includes a first coating layer and a second coating layer, and the first coating layer includes a compound containing at least one of Al, Ti, P, Si, Nb, Y, W, Cr, Zr, and La. The compound is at least one of an oxide, a hydroxide, and a salt.

[0113] In some embodiments, the second coating layer 144 includes a compound containing at least one of B, La, and Al.

[0114] In some embodiments, the second coating layer 144 includes a compound containing at least one of B, La, and Al, which includes at least one of an oxide, an acid, and a lithium-containing salt.

[0115] In some embodiments, the second coating layer 144 includes a boron-containing compound. The boron-containing compound includes at least one of a boron-containing oxide, a boron-containing acid, and a salt containing boron and lithium.

[0116] Optionally, boron-containing oxides include, but are not limited to, B2O3, B2O, and the like.

[0117] Optionally, the boron-containing acid includes, but is not limited to, H3BO3.

[0118] Optionally, the salt containing boron and lithium is Li i B j O k Optionally, the boron and lithium containing salts include, but are not limited to, B2O3, H3BO3, Li2O-B2O3, Li3BO3, Li2BO7, Li2BO7, and Li2BO 13At least one of the following may be included, but is not limited to:

[0119] In some embodiments, the second coating layer 144 includes an aluminum-containing compound. The aluminum-containing compound includes an aluminum-containing oxide or a salt containing boron and lithium. Optionally, the aluminum-containing oxide includes, but is not limited to, Al2O3. Optionally, the boron and lithium-containing salt includes, but is not limited to, Li3BO3.

[0120] In some embodiments, the second coating layer 144 includes a boron-containing compound, such as B2O3, H3BO3, Li2O-B2O3, Li3BO3, Li2BO7, Li2BO7, and Li2BO. 13 The boron-containing compound can chemically react with alkaline impurities on the surface of the high-nickel positive electrode material 100, thereby preventing the decomposition of Li2CO3 in the alkaline impurities on the surface of the material or the generation of gas due to a side reaction between the alkaline impurities and the electrolyte, and the boron-containing compound forms a stable coating layer on the surface of the high-nickel positive electrode material 100, thereby improving the stability of the high-nickel positive electrode material 100.

[0121] In some embodiments, M1 includes at least one of Mn and Al, hi some embodiments, M1 may be Mn, Al, or a mixture of Mn and Al.

[0122] In some embodiments, M2 comprises an element having an oxidation number of +4 or greater in the high-nickel positive electrode material.

[0123] In some embodiments, M3 comprises an element that has an oxidation number of +2 in the high-nickel positive electrode material.

[0124] In some embodiments, each of M2 and M3 comprises at least one of Zr, Ti, Nb, Ce, Hf, W, Mo, Ta, Ge, Sn, Sr, Mg, and Ba, and is different from M2 and M3.

[0125] In some embodiments, M4 comprises an element having an oxidation number of +3 or greater in the high-nickel positive electrode material.

[0126] In some embodiments, M4 comprises at least one of Al, Ti, P, Si, Nb, Y, W, Cr, Zr, and La.

[0127] In some embodiments, M5 comprises at least one of B, La, and Al.

[0128] In some embodiments, M5 comprises B.

[0129] (3) Characteristics and properties of positive electrode materials In some embodiments, XPS measurement of a powder sample of the high-nickel positive electrode material 100 is performed using AlKα radiation. NiP appears in the binding energy range of 850 eV to 870 eV. 3 / 2 Peak separation and fitting are performed on the peaks, and the standard deviation of the fitting, Σx 2 is less than 10%, and Ni 2+ / Ni 3+ The peak area ratio of Ni is greater than 1. 2+ / Ni 3+ may have a peak area ratio of 2, 3, 4, 5, etc., which is the Ni of the surface layer of the high nickel material according to the present disclosure. 2+ This indicates that the surface of the high-nickel positive electrode material 100 is relatively high in Cr, which can prevent the surface from being oxidized when lithium ions are released, and can contribute to maintaining the structural stability of the positive electrode material 100.

[0130] In some embodiments, XPS measurement of a powder sample is performed using AlKα radiation for the high-nickel positive electrode material 100. Peak separation and fitting are performed on the O1S peak appearing in the binding energy range of 526 eV to 540 eV, and the standard deviation of the fitting, Σx 2 is less than 10% and O1S 格子酸素 / O1S 不純物酸素 The area ratio of O1S is greater than 1 / 2. O2 impurities refer to oxygen in compounds such as LiOH, Li2CO3, and Li2SO4. Optionally, O1S 格子酸素 / O1S 不純物酸素 The area ratios of O1S can be 0.532, 0.525 and 0.573, 0.58, 0.59, etc. 格子酸素 / O1S 不純物酸素 If the area ratio falls within the above range, alkaline impurities (such as Li2CO3 and LiOH) on the surface of the high-nickel positive electrode material 100 can be reduced, which can contribute to reducing the amount of gas generated in a battery manufactured using the high-nickel positive electrode material 100.

[0131] In some embodiments, the alkaline impurities on the surface of the high-nickel positive electrode material 100 mainly refer to Li2CO3 and LiOH, and the mass fraction of Li2CO3 in the high-nickel positive electrode material 100 is less than 0.3 wt%. For example, the mass fraction of Li2CO3 in the high-nickel positive electrode material 100 can be 0.05 wt%, 0.1 wt%, 0.12 wt%, 0.2 wt%, etc., and may be other values ​​within the above range, without being limited thereto. In some exemplary embodiments, the mass fraction of Li2CO3 in the high-nickel positive electrode material 100 is less than 0.13 wt%.

[0132] In some embodiments, the mass fraction of LiOH in the high-nickel positive electrode material 100 is less than 0.3 wt%. For example, the mass fraction of LiOH in the high-nickel positive electrode material 100 can be 0.05 wt%, 0.08 wt%, 0.1 wt%, 0.2 wt%, etc., and can be other values ​​within the above ranges without being limited thereto. In some exemplary embodiments, the mass fraction of LiOH in the high-nickel positive electrode material 100 is less than 0.1 wt%.

[0133] Keeping the mass fraction of Li2CO3 and LiOH in the high-nickel positive electrode material 100 within the above range can improve the processing performance of the high-nickel positive electrode material 100 and contribute to suppressing gas generation in batteries manufactured using the high-nickel positive electrode material 100.

[0134] In some embodiments, the crystalline structure of the high-nickel positive electrode material 100 is a hexagonal or monoclinic crystalline structure.

[0135] The hexagonal crystal structure is P3, P31, P32, R3, P-3, R-3, P312, P321, P3112, P3121, P3212, P3221, R32, P3m1, P 31m, P3c1, P31c, R3m, R3c, P-31m, P-31c, P-3m1, P-3c1, R-3m, R-3c, P6, P61, P65, P62, P64, P63 , P-6, P6 / m, P63 / m, P622, P6122, P6522, P6222, P6422, P6322, P6mm, P6cc, P63cm, P63mc, P-6m2, P-6c2, P-62m, P-62c, P6 / mmm, P6 / mcc, P63 / mcm and P63 / mmc.

[0136] The monoclinic crystal structure belongs to any one space group selected from the group consisting of P2, P21, C2, Pm, Pc, Cm, Cc, P2 / m, P21 / m, C2 / m, P2 / c, P21 / c and C2 / c.

[0137] In some representative embodiments, in order to obtain a secondary battery with a relatively high discharge capacity, the crystal structure of the high-nickel cathode material 100 is a hexagonal crystal structure belonging to the space group R-3m or a monoclinic crystal structure belonging to the space group C2 / m.

[0138] In some embodiments, the morphology of the crystal particles of the high-nickel cathode material 100 includes at least one of substantially spherical, substantially cubic, and substantially rectangular parallelepiped shapes.

[0139] In some embodiments, the pH of the high-nickel cathode material 100 is 10 < pH < 12. In some embodiments, the pH of the high-nickel cathode material 100 is 10.5 < pH < 11.7. In some embodiments, the pH of the high-nickel cathode material 100 is, for example, a value within the range of 11.1 < pH < 11.9, 10.5 < pH < 11.0, or 11.0 < pH < 11.7, such as 10.6, 10.8, 11.0, 11.2, 11.3, and 11.5. Other values within the above range may also be possible and are not limited herein. If the pH of the high-nickel cathode material 100 is within the above range, it can contribute to further improvement of the processing performance of the high-nickel cathode material 100. For example, it can improve the stability of the cathode material during the battery manufacturing process, and it is less likely to precipitate or shed powder when the cathode material is mixed with an adhesive. In some representative embodiments, the pH of the high-nickel cathode material 100 is 11.0 < pH < 11.5. In some other representative embodiments, the pH of the high-nickel cathode material 100 is 11.2 < pH < 11.3.

[0140] In some embodiments, the powder conductivity of the high-nickel positive electrode material 100 is greater than 0.02 S / cm. In some embodiments, the powder conductivity of the high-nickel positive electrode material 100 is specifically, for example, a value within a range of 0.03 S / cm to 0.08 S / cm, 0.05 S / cm to 0.08 S / cm, or 0.03 S / cm to 0.05 S / cm, such as 0.03 S / cm, 0.04 S / cm, 0.05 S / cm, 0.06 S / cm, and 0.07 S / cm, and may be other values ​​within the above ranges and is not limited thereto.

[0141] In some embodiments, the specific surface area of ​​the high nickel positive electrode material 100 is 0.3 m 2 / g~0.8m 2 In some embodiments, the specific surface area of ​​the high-nickel cathode material 100 is, for example, 0.3 m 2 / g~0.5m 2 / g, 0.5m 2 / g~0.8m 2 / g or 0.4m 2 / g~0.7m 2 / g, for example, 0.3m 2 / g, 0.4m 2 / g, 0.5m 2 / g, 0.6m 2 / g, 0.7m 2 / g and 0.8m 2 / g, etc. Other values ​​within the above range may also be used and are not limited thereto. By keeping the specific surface area of ​​the cathode material 100 according to the present disclosure within the above range, the stability and electrochemical performance of the material can be further improved, problems such as powder falling and gas generation during the manufacturing process caused by an excessively large specific surface area can be prevented, and problems such as a decrease in battery capacity and rate caused by an excessively small specific surface area can be prevented.

[0142] In some embodiments, the median diameter of the high-nickel positive electrode material 100 is 2.5 μm to 4.5 μm. In some embodiments, the median diameter of the high-nickel positive electrode material 100 is, for example, within a range of 3.0 μm to 4.5 μm, 2.5 μm to 4.0 μm, or 3.0 μm to 4.0 μm, such as 2.5 μm, 3 μm, 3.5 μm, 4 μm, and 4.5 μm. Keeping the average particle diameter of the high-nickel positive electrode material 100 within the above range can contribute to improving the press density, powder conductivity, and cycle life of the high-nickel positive electrode material 100 in the positive electrode plate.

[0143] II. Preparation of the cathode material One embodiment of the present disclosure further provides a method for preparing a high-nickel positive electrode material, the method comprising the steps of: Step S100: A metal composite hydroxide precursor, a lithium-containing compound, and a dopant are mixed and subjected to a primary heat treatment to obtain a substrate material. The dopant includes an M2 element and an M3 element. The corresponding compound of the M2 element is at least one of an oxide, hydroxide, and lithium metal oxide containing only M2, in which the oxidation state of M2 in the compound is +4 or higher. The corresponding compound of the M3 element is at least one of an oxide and hydroxide containing only M3, in which the oxidation state of M3 in the compound is +2. Step S200: The substrate material obtained in step S100 is coated to obtain a high-nickel positive electrode material.

[0144] In the above technical solution, in the dopant containing the M2 element and the M3 element according to the present disclosure, the ion conduction ability of the M2 element is relatively low, and the ion conduction ability of the M3 element is relatively high. In the present disclosure, after a primary heat treatment is performed on the dopant containing the M2 element and the M3 element, the metal composite hydroxide precursor, and the lithium-containing compound, the M2 element is doped on the surface of the material, and the M2 element is mainly unevenly distributed at the grain boundaries of the material, while the M3 element is doped inside the crystals of the material. Since the M2 element, which has an oxidation number of +4 or more, is present on the surface of the material, the balance of the oxidation numbers causes the Ni on the surface of the material to be doped. 3+ As the amount of Ni decreases,2+ The amount of M3 increases, which prevents the surface of the cathode material from being oxidized when lithium ions are released, contributing to maintaining the structural stability of the cathode material. The presence of the M3 element, which has an oxidation number of +2, inside the material can suppress the phase transition from H2 to H3 during the charge and discharge process of the material, improving structural stability. Furthermore, M3 occupies a portion of the Li ions in the lattice inside the material. + The M2 and M3 elements can be substituted at the M2 site without affecting the layered structure of the material. The present disclosure improves the stability of high-nickel positive electrode materials by doping the substrate material with ions containing M2 and M3 elements, further improving the capacity performance of the high-nickel positive electrode materials. The preparation method according to the present disclosure will be described in detail below with reference to embodiments and examples.

[0145] Before step S100, a metal composite hydroxide precursor is prepared. Preparing the metal composite hydroxide precursor includes mixing a metal salt solution, a complexing agent, and a pH adjuster by a coprecipitation method to obtain the metal composite hydroxide precursor.

[0146] In some embodiments, the mass ratio of the metal salt solution to the complexing agent to the pH adjuster is 1:(0.01-0.10):(0.1-0.8). In some embodiments, the mass ratio of the metal salt solution to the complexing agent to the pH adjuster is specifically within the range of, for example, 1:(0.05-0.10):(0.1-0.8), 1:(0.01-0.10):(0.4-0.8), or 1:(0.05-0.10):(0.1-0.5), such as 1:0.01:0.1, 1:0.05:0.3, 1:0.1:1.5, and 1:0.08:0.8. In the present disclosure, if the mass ratio of the metal salt solution, the complexing agent, and the pH adjuster is within the above range, it is possible to promote regular growth of the primary particles (i.e., diametric crystal growth), contribute to keeping the size of the material particles within a specified range, contribute to improving the tap density and particle size distribution of the material, and therefore ensure that the particles do not crack.

[0147] In some embodiments, the metal salt solution comprises at least one of a nickel salt solution, a cobalt salt solution, a manganese salt solution, and an aluminum salt solution.

[0148] In some embodiments, the nickel salt solution comprises at least one of nickel sulfate, nickel chloride, nickel sulfamate, nickel bromide, nickel (II) hydroxide, and nickel carbonyl.

[0149] In some embodiments, the cobalt salt solution comprises at least one of cobalt sulfate, cobalt chloride, and cobalt nitrate.

[0150] In some embodiments, the manganese salt solution comprises at least one of manganese sulfate, manganese nitrate, and manganese chloride.

[0151] In some embodiments, the aluminum salt solution comprises at least one of sodium aluminate, aluminum sulfate, aluminum chloride, and potassium aluminate.

[0152] In some embodiments, the complexing agent may be selected from those capable of forming a complex with nickel, cobalt, manganese, or aluminum ions in an aqueous solution. In some embodiments, the complexing agent includes at least one of an ammonium ion donor, hydrazine, ethylenediaminetetraacetic acid, nitrilotriacetic acid, uracildiacetic acid, and glycine, and the ammonium ion donor includes at least one of aqueous ammonia, ammonium sulfate, ammonium chloride, ammonium carbonate, and ammonium fluoride.

[0153] In some embodiments, the mixing temperature is 10°C to 80°C. In some embodiments, the mixing temperature is, for example, within a range of 10°C to 50°C, 40°C to 80°C, or 20°C to 60°C, such as 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, and 80°C. Other values ​​within the above ranges are also possible and are not limited thereto. In some exemplary embodiments, the mixing temperature is 20°C to 70°C. Keeping the temperature of the coprecipitation reaction within the above range can contribute to the growth of precursor crystal grains.

[0154] In some embodiments, the pH adjuster comprises an alkali metal hydroxide.

[0155] In some embodiments, the alkali metal hydroxide comprises at least one of sodium hydroxide and potassium hydroxide.

[0156] In some embodiments, the pH of the mixing process is 9 to 13. In some embodiments, the pH of the mixing process is, for example, a value within the range of 9 to 12, 10 to 13, or 10 to 12, such as 9, 10, 11, 12, and 13. Other values ​​within the above ranges are also possible and are not limited thereto. In some exemplary embodiments, the pH of the mixing process is 11 to 13.

[0157] In some embodiments, the mixing time is 10 to 200 hours. In some embodiments, the mixing time is specifically within a range of, for example, 50 to 200 hours, 10 to 150 hours, or 50 to 150 hours, such as 10 hours, 20 hours, 30 hours, 40 hours, 50 hours, 60 hours, 70 hours, 80 hours, 90 hours, 100 hours, 110 hours, 120 hours, 130 hours, 140 hours, 150 hours, 160 hours, 180 hours, 180 hours, 190 hours, and 200 hours. Other values ​​within the above ranges may also be used and are not limited thereto.

[0158] In some embodiments, the mixing treatment is performed with stirring, and the stirring speed is 800 rpm to 1200 rpm. In some embodiments, the stirring speed is specifically within the range of, for example, 1000 rpm to 1200 rpm, 800 rpm to 1000 rpm, or 900 rpm to 1100 rpm, such as 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, and 1200 rpm. Other values ​​within the above ranges may also be used, and are not limited thereto.

[0159] In some embodiments, the mixing treatment is carried out in a reaction vessel, which is at least one of a continuous type in which the reaction vessel overflows to separate the formed metal composite hydroxide, and a batch type in which the reaction vessel is not discharged to the outside of the system until the reaction is completed.

[0160] In some embodiments, the metal composite hydroxide precursor prepared by the mixing treatment is a slurry suspension, and is obtained through solid-liquid separation, washing, and drying.

[0161] In some embodiments, the method of solid-liquid separation includes any one of centrifugation or filtration. The purpose of solid-liquid separation is to separate the metal complex hydroxide from the solvent.

[0162] In some embodiments, the washing involves multiple washes with deionized water to remove impurities.

[0163] In some embodiments, the drying temperature is 100° C. to 130° C. In some embodiments, the drying temperature is, for example, a value within a range of 100° C. to 120° C., 110° C. to 130° C., or 110° C. to 120° C., such as 100° C., 110° C., 120° C., or 130° C. Other values ​​within the above ranges are also possible and are not limited thereto.

[0164] In some embodiments, the drying time is 12 to 24 hours. Specifically, the drying time is, for example, 15 to 24 hours, 12 to 20 hours, or a value within a range of 15 to 20 hours, such as 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, and 24 hours. Other values ​​within the above ranges may also be used and are not limited thereto.

[0165] In some embodiments, the average particle size of the metal composite hydroxide precursor is 3 μm to 10 μm. In some embodiments, the median size of the metal composite hydroxide precursor is, for example, a value within a range of 5 μm to 10 μm, 3 μm to 8 μm, or 5 μm to 9 μm, such as 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, and 10 μm. Other values ​​within the above ranges are also possible and are not limited thereto.

[0166] Step S100: A metal composite hydroxide precursor, a lithium-containing compound, and a dopant are mixed and subjected to a primary heat treatment to obtain a substrate material. The dopant includes a compound containing an M2 element and a compound containing an M3 element. The compound corresponding to the M2 element is at least one of an oxide, hydroxide, and lithium metal oxide containing only M2, in which the oxidation number of the M2 element in the compound is +4 or higher. The compound corresponding to the M3 element is at least one of an oxide and hydroxide containing only M3, in which the oxidation number of the M3 element in the compound is +2.

[0167] In the above steps, by adding dopants and performing the primary heat treatment, the M2 element with an oxidation number of +4 or higher is mainly doped on the surface of the material, and the M3 element with an oxidation number of +2 mainly penetrates into the interior of the material. After the primary heat treatment, the M3 element can directly penetrate into the interior of the crystal and replace some of the Li sites, and the M2 element is mainly concentrated at the grain boundaries of the material, and the small amount of M2 element is guided by the M3 element to penetrate into the interior of the crystal and partially replace the element sites inside the crystal.

[0168] In some embodiments, the mass ratio of the metal composite hydroxide precursor, the lithium-containing compound, and the dopant is 1:(0.46 - 0.49):(0.001 - 0.005). In some embodiments, the mass ratio of the metal composite hydroxide precursor, the lithium-containing compound, and the dopant is, for example, a value within the range of 1:(0.46 - 0.48):(0.001 - 0.003), 1:(0.46 - 0.47):(0.001 - 0.002), or 1:(0.45 - 0.47):(0.002 - 0.003), such as 1:0.46:0.002, 1:0.47:0.003, 1:0.48:0.001, 1:0.047:0.002, and 1:0.048:0.01, etc. Other values within the above range may also be used and are not limited herein. In the present disclosure, if the mass ratio of the metal composite hydroxide precursor, the lithium-containing compound, and the dopant is within the above range, the discharge capacity and rate capacity of the material can be further improved, whereby the material can maintain a relatively high capacity retention rate and a relatively low DCR increase rate. When the mass ratio of the metal composite hydroxide precursor to the lithium-containing compound is small, it affects the discharge capacity and rate capacity of the material. When the mass ratio of the metal composite hydroxide precursor to the lithium-containing compound is large, the residual alkali on the material surface increases, the capacity decreases, and the cost increases.

[0169] In some embodiments, the atomic ratio of the total number of metal atoms Me in the metal composite hydroxide precursor to the number of Li atoms in the lithium-containing compound is 1.0 < Li / Me < 1.2. In some embodiments, Li / Me is 1.01, 1.05, 1.1, 1.15, 1.19, etc. Me represents the total number of all metal atoms in the metal composite hydroxide precursor. If the atomic ratio of the total number of metal atoms Me in the metal composite hydroxide precursor to the number of Li atoms in the lithium-containing compound is within the above range, it can contribute to the formation of the matrix material crystal grains and the improvement of the electrochemical performance of the material.

[0170] In some embodiments, the lithium-containing compound includes a lithium-containing salt and a lithium-containing hydroxide, hi some embodiments, the lithium-containing compound includes at least one of lithium carbonate, lithium hydroxide, lithium nitrate, and lithium acetate.

[0171] In some embodiments, each of the M2 and M3 elements includes at least one of Zr, Ti, Nb, Ce, Hf, W, Mo, Ta, Ge, Sn, Sr, Mg, and Ba, and is different from M2 and M3. In some embodiments, the dopant includes at least one of lithium zirconate, lithium titanate, niobium oxide, lithium tungstate, barium oxide, and magnesium hydroxide.

[0172] In some embodiments, the molar ratio n M2 :n M3 is 2:1 or greater. In some embodiments, n M2 :n M3 is, for example, within the range of (2-6):1, (2-5):1, or (3-5):1, such as 2:1, 3:1, 4:1, 5:1, and 6:1. Within the above range, elements with higher oxidation numbers (M2 elements with oxidation numbers of +4 or higher) can be effectively doped into the surface layer of the material, while elements with lower oxidation numbers (M3 elements with oxidation numbers of +2) can penetrate into the interior of the material with only a small addition. Adding too much low-valent element can suppress the electrochemical performance of the material. In some embodiments, the molar ratio of M2 element to M3 element in the dopant is 3:1≦n M2 :n M3 ≦5:1.

[0173] In some embodiments, the average particle size of the dopant is 10 nm to 50 nm. In some embodiments, the average particle size of the dopant is specifically, for example, a value within a range of 10 nm to 40 nm, 20 nm to 50 nm, or 20 nm to 40 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, and 50 nm. Other values ​​within the above ranges may also be used and are not limited thereto.

[0174] In some embodiments, the temperature of the primary heat treatment is 680°C to 900°C. In some embodiments, the temperature of the primary heat treatment is, for example, a value within a range of 700°C to 900°C, 680°C to 800°C, or 700°C to 800°C, such as 680°C, 700°C, 720°C, 750°C, 780°C, 800°C, 820°C, 850°C, and 900°C. Other values ​​within the above ranges are also possible and are not limited thereto. In some exemplary embodiments, the temperature of the primary heat treatment is 780°C to 870°C. Keeping the temperature of the primary heat treatment within the above range can contribute to the growth of crystal grains in the high-nickel positive electrode material.

[0175] In some embodiments, the duration of the primary heat treatment is 5 to 20 hours. In some embodiments, the duration of the primary heat treatment is, for example, within a range of 5 to 15 hours, 10 to 20 hours, or 10 to 18 hours, such as 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 18, 19, and 20 hours. Other values ​​within the above ranges are also possible and are not limited thereto. In some exemplary embodiments, the duration of the primary heat treatment is 8 to 15 hours.

[0176] In some embodiments, the temperature rise rate of the primary heat treatment is 50°C / h to 550°C / h. In some embodiments, the temperature rise rate of the primary heat treatment is, for example, within a range of 100°C / h to 550°C / h, 150°C / h to 500°C / h, or 200°C / h to 300°C / h, such as 50°C / h, 100°C / h, 140°C / h, 200°C / h, 250°C / h, 300°C / h, 380°C / h, 400°C / h, 450°C / h, 500°C / h, and 550°C / h. Other values ​​within the above ranges are also possible and are not limited thereto. In some representative embodiments, the temperature rise rate of the primary heat treatment is 100°C / h to 400°C / h. In other representative embodiments, the temperature rise rate of the primary heat treatment is 140°C / h to 380°C / h.

[0177] In some embodiments, the oxygen content of the substrate material is 85% or more. In some embodiments, the oxygen content of the substrate material is, for example, within a range of 85% to 98%, 85% to 95%, or 89% to 97%, such as 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, etc. Other values ​​within the above ranges are also possible and are not limited thereto. In some exemplary embodiments, the oxygen content of the substrate material is 95% or more.

[0178] In some embodiments, the primary heat treatment equipment comprises a static box furnace or a roller hearth continuous furnace. Step S200: The substrate material obtained in step S100 is coated to obtain a high-nickel positive electrode material. Step 201: Mixing a substrate material with a first coating agent and subjecting it to a secondary heat treatment to obtain a primary coating product.

[0179] In some embodiments, the mass ratio of the substrate material to the first coating agent is 1000:(0.5-3). In some embodiments, the mass ratio of the substrate material to the first coating agent is specifically within the range of, for example, 1000:(1-3), 1000:(1.5-3), or 1000:(2.5-3), such as 1000:0.5, 1000:1, 1000:1.5, 1000:2, 1000:2.5, and 1000:3. Other values ​​within the above ranges are also possible and are not limited thereto.

[0180] In some embodiments, the first coating agent includes a metal element or a nonmetal element having an oxidation number of +3 or more. In the present disclosure, by adding a metal element or a nonmetal element having an oxidation number of +3 or more, the Ni on the surface of the high nickel positive electrode material is balanced by the oxidation number. 2+ The amount of the hydroxybenzoate will remain unchanged or even increase, thus improving the stability of the material structure, preventing the formation of alkaline impurities due to contact between the material and water in the air, and suppressing the generation of gas in the material.

[0181] In some embodiments, the first coating agent comprises at least one oxide, salt, or hydroxide of a metal element or non-metal element having an oxidation number of +3 or greater.

[0182] In some embodiments, the metallic or non-metallic element comprises at least one of Al, Ti, P, Si, Nb, Y, W, Cr, Zr, or La.

[0183] In some embodiments, the first coating material is at least one of lithium aluminate, lithium titanate, lithium lanthanum titanate, yttrium oxide, aluminum oxide, and titanium oxide.

[0184] In some embodiments, the temperature of the secondary heat treatment is 600°C to 800°C. In some embodiments, the temperature of the secondary heat treatment is, for example, a value within a range of 650°C to 800°C, 600°C to 750°C, or 700°C to 800°C, such as 600°C, 650°C, 680°C, 700°C, 720°C, 750°C, 780°C, and 800°C. Other values ​​within the above ranges are also possible and are not limited thereto. In some exemplary embodiments, the temperature of the secondary heat treatment is 650°C to 750°C.

[0185] In some embodiments, the duration of the secondary heat treatment is 1 hour to 20 hours. In some embodiments, the duration of the secondary heat treatment is, for example, within a range of 5 hours to 20 hours, 10 hours to 20 hours, or 5 hours to 10 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 18 hours, 18 hours, 19 hours, and 20 hours. Other values ​​within the above ranges are also possible and are not limited thereto. In some exemplary embodiments, the duration of the secondary heat treatment is 3 hours to 10 hours.

[0186] In some embodiments, the temperature rise rate of the secondary heat treatment is 50°C / h to 550°C / h. In some embodiments, the temperature rise rate of the secondary heat treatment is, for example, a value within a range of 100°C / h to 550°C / h, 50°C / h to 500°C / h, or 150°C / h to 450°C / h, such as 50°C / h, 100°C / h, 140°C / h, 200°C / h, 250°C / h, 300°C / h, 380°C / h, 400°C / h, 450°C / h, 500°C / h, and 550°C / h. Other values ​​within the above ranges are also possible and are not limited thereto. In some representative embodiments, the temperature rise rate of the secondary heat treatment is 100°C / h to 400°C / h. In other representative embodiments, the temperature rise rate of the secondary heat treatment is 140°C / h to 380°C / h.

[0187] In some embodiments, the oxygen content in the primary coating product is 85% or more. In some embodiments, the oxygen content in the primary coating product is within a range of, for example, 85% to 95%, 90% to 97%, or 89% to 97%, such as 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, and 97%. Other values ​​within the above ranges are also possible and are not limited thereto. In some exemplary embodiments, the oxygen content in the primary coating product is 95% or more.

[0188] In some embodiments, the secondary heat treatment equipment comprises a static box furnace or a roller hearth continuous furnace.

[0189] In some embodiments, the substrate material and the first coating material are mixed and subjected to a secondary heat treatment, followed by cleaning under isothermal conditions, and then drying under vacuum conditions to obtain a primary coating result.

[0190] In some embodiments, the temperature under isothermal conditions is 10° C. to 25° C. In some embodiments, the temperature under isothermal conditions is, for example, 15° C. to 25° C., 10° C. to 20° C., or a value within a range of 15° C. to 20° C., such as 10° C., 11° C., 12° C., 13° C., 14° C., 15° C., 16° C., 17° C., 18° C., 19° C., 20° C., 21° C., 22° C., 23° C., 24° C., and 25° C. Other values ​​within the above ranges are also possible and are not limited thereto.

[0191] In some embodiments, the drying temperature is 100° C. to 200° C. In some embodiments, the drying temperature is specifically within the range of 120° C. to 200° C., 150° C. to 200° C., or 100° C. to 150° C., such as 100° C., 110° C., 120° C., 130° C., 140° C., 150° C., 160° C., 170° C., 180° C., 190° C., and 200° C. Other values ​​within the above ranges are also possible and are not limited thereto.

[0192] Step S202: Mix the primary coating product with the second coating agent and perform a tertiary heat treatment to obtain a high-nickel positive electrode material.

[0193] In some embodiments, the second coating layer 144 includes a compound containing at least one of B, La, and Al.

[0194] In some embodiments, the second coating layer 144 includes a compound containing at least one of B, La, and Al, which is an oxide, an acid, or a lithium-containing salt.

[0195] In some embodiments, the second coating layer 144 includes a boron-containing compound, such as a boron-containing oxide, a boron-containing acid, or a salt containing boron and lithium.

[0196] Optionally, the boron-containing oxides include, but are not limited to, B2O3 or B2O.

[0197] Optionally, the boron-containing acid includes, but is not limited to, H3BO3.

[0198] Optionally, the salt containing boron and lithium is Li i B j O k Optionally, the boron and lithium containing salts include, but are not limited to, B2O3, H3BO3, Li2O-B2O3, Li3BO3, Li2BO7, Li2BO7, and Li2BO. 13 At least one of the following may be included, but is not limited to:

[0199] In some embodiments, the second coating agent is a boron-containing compound. Boron-containing compounds include B2O3, H3BO3, Li2O-B2O3, Li3BO3, Li2BO7, Li2BO7, and Li2BO 13By adding a boron-containing compound to the primary coating product, the boron-containing compound can chemically react with alkaline impurities on the surface of the material and form a stable coating layer that covers the surface of the material, thereby reducing the alkaline impurities on the surface of the material and protecting the surface of the material, and reducing gas generation due to decomposition of Li2CO3 in the alkaline impurities on the surface of the material and gas generation due to side reactions between the alkaline impurities on the surface of the material and the electrolyte.

[0200] In some embodiments, the mass ratio of the primary coating product to the second coating agent is 1:(0.0005-0.005). In some embodiments, the mass ratio of the primary coating product to the second coating agent is, for example, within the range of 1:(0.0008-0.003), 1:(0.001-0.0025), or 1:(0.0015-0.002), such as 1:0.0005, 1:0.0007, 1:0.0009, 1:0.001, 1:0.0015, 1:0.002, 1:0.0025, 1:0.003, etc. Other values ​​within the above ranges are also possible and are not limited thereto.

[0201] In some embodiments, the temperature of the third heat treatment is 200°C to 400°C. In some embodiments, the temperature of the third heat treatment is, for example, a value within a range of 200°C to 300°C, 300°C to 400°C, or 250°C to 350°C, such as 200°C, 250°C, 280°C, 300°C, 320°C, 360°C, 380°C, and 400°C. Other values ​​within the above ranges are also possible and are not limited thereto. In a typical embodiment, the temperature of the third heat treatment is 250°C to 360°C.

[0202] In some embodiments, the duration of the third heat treatment is 1 hour to 20 hours. In some embodiments, the duration of the third heat treatment is, for example, within a range of 5 hours to 20 hours, 1 hour to 15 hours, or 4 hours to 16 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 18 hours, 18 hours, 19 hours, or 20 hours. Other values ​​within the above ranges are also possible and are not limited thereto. In some exemplary embodiments, the duration of the third heat treatment is 5 hours to 10 hours.

[0203] In some embodiments, the temperature rise rate of the third heat treatment is 50°C / h to 550°C / h. In some embodiments, the temperature rise rate of the third heat treatment is, for example, a value within a range of 200°C / h to 550°C / h, 50°C / h to 350°C / h, or 200°C / h to 300°C / h, such as 50°C / h, 100°C / h, 140°C / h, 200°C / h, 250°C / h, 300°C / h, 380°C / h, 400°C / h, 450°C / h, 500°C / h, and 550°C / h. Other values ​​within the above ranges are also possible and are not limited thereto. In a representative embodiment, the temperature rise rate of the third heat treatment is 100°C / h to 400°C / h. In some other representative embodiments, the temperature rise rate of the third heat treatment is 140°C / h to 380°C / h.

[0204] In some embodiments, the oxygen content in the high-nickel positive electrode material is 85% or greater. In some embodiments, the oxygen content in the high-nickel positive electrode material is, for example, within a range of 85% to 98%, 85% to 95%, or 89% to 97%, such as 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, and 97%. Other values ​​within the above ranges are also possible and are not limited thereto. In some exemplary embodiments, the oxygen content in the high-nickel positive electrode material is 95% or greater.

[0205] In some embodiments, the tertiary heat treatment equipment includes a static box furnace or a roller hearth continuous furnace.

[0206] In some embodiments, the tertiary heat treatment further comprises the steps of sieving and demagnetizing.

[0207] In some embodiments, the mesh of the sieve used for sieving is 200 mesh to 400 mesh. In some embodiments, the mesh of the sieve is, for example, within the range of 300 mesh to 400 mesh, 200 mesh to 300 mesh, or 240 mesh to 360 mesh, such as 200 mesh, 210 mesh, 250 mesh, 280 mesh, 300 mesh, 350 mesh, 380 mesh, and 400 mesh. Other values ​​within the above ranges may also be used and are not limited thereto.

[0208] III.Battery An embodiment of the present disclosure further provides a lithium-ion secondary battery including a positive electrode plate, a negative electrode plate, a separator, a non-aqueous electrolyte, and a case. In some embodiments, the positive electrode plate includes a current collector and the high-nickel positive electrode material described above or a positive electrode material prepared by the method for preparing a high-nickel positive electrode material described above, applied to the current collector.

[0209] The present disclosure has the following advantageous effects compared to the prior art. For the high-nickel positive electrode material according to the present disclosure, XPS measurement of a powder sample was performed using AlKα radiation. Ni2P appears in the binding energy range of 850 eV to 870 eV. 3 / 2 After peak separation and fitting, Ni 2+ The peak area S1 of Ni 3+ The peak area S2 of Ni 2+ The half-width α of the peak and Ni 3+ The half-value width β of the peak satisfies the relationship S1 / (S1+S2)>0.5 and 0.9<α / β<1.5. As can be seen from this, the surface of the high-nickel positive electrode material according to the present disclosure is 3+ The amount of Ni is relatively small. 2+The relatively large amount of Ni can prevent the surface of the high-nickel positive electrode material from being oxidized during the desorption of lithium ions, contribute to maintaining the stability of the structure of the positive electrode material, prevent the loss of the positive electrode active material and electrolyte during the charge and discharge process, further increase the capacity of the positive electrode material, and significantly improve the high-temperature cycle performance of the high-nickel positive electrode material. 3+ The amount of Ni is relatively small 2+ Since the amount of is relatively large, it is possible to suppress the occurrence of cracks inside the material during the charge and discharge process and to stabilize the internal structure of the material. As a result, when the positive electrode material according to the present disclosure is used in a battery, the increase in the DC internal resistance of the battery during long-term cycles is significantly suppressed.

[0210] In the present disclosure, after a primary heat treatment is performed on a dopant containing an M2 element with an oxidation number of +4 or more and an M3 element with an oxidation number of +2, the M2 element is doped on the surface of the material, and the M3 element is doped inside the material. Since the M2 element with an oxidation number of +4 or more is present on the surface of the material, Ni is doped on the surface of the material due to the balance of the oxidation numbers. 3+ As the amount of Ni decreases, 2+ The amount of M3 increases, which prevents the surface of the cathode material from being oxidized when lithium ions are released, contributing to maintaining the structural stability of the cathode material. The M3 element, which has an oxidation number of +2, penetrates into the material, suppressing the phase transition from H2 to H3 during the charge and discharge process of the material, improving structural stability. Furthermore, M3 occupies part of the Li ions in the lattice inside the material. + The present disclosure provides a method for forming a substrate material using a dopant containing an M2 element and an M3 element, thereby improving the stability of the high-nickel positive electrode material and further improving the capacity performance of the high-nickel positive electrode material.

[0211] Although the embodiments of the present disclosure are described, the present disclosure is not limited to these embodiments unless it deviates from the spirit of the present disclosure.

[0212] Example Example 1 (1) Ni by coprecipitation 0.885 Co 0.09 Mn 0.025 (OH) precursor was prepared and Ni 0.885 Co 0.09 Mn 0.025 The (OH)2 precursor, LiOH·H2O, and nano-sized TiO2, ZrO2, and MgO dopants were uniformly mixed, where (n TiO2 +n ZrO2 ):n MgO = 3:1, and the substrate material was prepared by a primary heat treatment at a temperature of 830°C, where Li / Me = 1.05 and Me = the total number of atoms of Ni, Co, and Mn (M represents the metal in the metal composite hydroxide precursor). (2) The substrate material prepared in step (1) and nano-sized Al2O3 were uniformly mixed in a mass ratio of 1:0.002, and then subjected to a secondary heat treatment at a temperature of 700°C. The material obtained by the secondary heat treatment was placed in distilled water and washed with water while maintaining the temperature at 25°C. After the dehydration process, the mixture was dried in a vacuum atmosphere at a temperature of 150°C to obtain a primary coating product. (3) The primary coating product and H3BO3 (i.e., the second coating material) were uniformly mixed in a mass ratio of 1:0.001, and then subjected to a third heat treatment at a temperature of 300°C. After further sieving and demagnetization, a high-nickel positive electrode material was obtained.

[0213] 19, the cathode material 100 according to this example has a schematic structure in which a first coating layer 142 is formed on the surface of primary particles 122 (the primary particles 122 are the substrate material prepared in step (1)) (i.e., the primary coating product prepared in step (2)), and a second coating layer 144 is formed on the surface of the first coating layer 142, and the particles in the cathode material 100 as a whole have a single-crystal particle structure (i.e., prepared in step (3)). FIG. 2 is an SEM photograph of the high-nickel cathode material according to this example, and as shown in FIG. 2, the morphology of the crystal particles includes substantially spherical, substantially cubic, and substantially rectangular.

[0214] Example 2 The only difference from Example 1 is the following: In step (1), (n TiO2 +n ZrO2 ):n MgO =1:1. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0215] Example 3 The only difference from Example 1 is the following: In step (1), (n TiO2 +n ZrO2 ):n MgO =2:1. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0216] Example 4 The only difference from Example 1 is the following: In step (1), (n TiO2 +n ZrO2 ):n MgO =4:1. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0217] Example 5 The only difference from Example 1 is the following: In step (1), (n TiO2 +n ZrO2 ):n MgO =5:1. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0218] Example 6 The only difference from Example 1 is the following: In step (1), (n TiO2 +n ZrO2 ):n MgO =6:1. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0219] Example 7 The only difference from Example 1 is the following: In step (1), (n TiO2 +n ZrO2 ):n MgO =7:1. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0220] Example 8 The only difference from Example 1 is that in step (1), WO3, ZrO2, and MgO were used as dopants, and (n WO3 +n ZrO2 ):n MgO =3:1. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0221] Example 9 The only difference from Example 1 is that in step (1), WO3, ZrO2, and Y2O3 were used as dopants, and (n WO3 +n ZrO2 ):n Y2O3 =3:1. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0222] Example 10 The only difference from Example 1 is that in step (1), MoO3, ZrO2, and Y2O3 were used as dopants, and (n MoO3 +n ZrO2 ):n Y2O3 =3:1. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0223] Example 11 The only difference from Example 1 is that in step (1), MoO3, ZrO2, and Al2O3 were used as dopants, and (n MoO3 +n ZrO2 ):n Al2O3 =3:1. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0224] Example 12 The only difference from Example 1 is that ZrO2 and MgO are used as dopants in step (1), and n ZrO2 :n MgO =3:1. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0225] Example 13 The only differences from Example 1 are as follows: In step (1), the temperature of the primary heat treatment was 650°C. 20 is a schematic diagram of a cathode material 100 according to this example. The structure of the high-nickel cathode material according to this example is similar to that of Example 1, but differs from Example 1 in that some primary particles 122 aggregate to form secondary particles 124, and some of the particles in the cathode material exist in a polycrystalline particle structure, i.e., some are distributed in the form of secondary particles.

[0226] Example 14 The only difference from Example 1 is the following: In step (1), the temperature of the primary heat treatment is 680°C. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a polycrystalline particle structure as a whole, that is, distributed in the form of secondary particles.

[0227] Example 15 The only differences from Example 1 are as follows: In step (1), the temperature of the primary heat treatment was 700°C. The structure of the high-nickel positive electrode material of this example is similar to that of Example 13, and the particles in the positive electrode material are present as a polycrystalline particle structure as a whole, that is, distributed in the form of secondary particles.

[0228] Example 16 The only differences from Example 1 are as follows: In step (1), the temperature of the primary heat treatment was 850°C. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0229] Example 17 The only differences from Example 1 are as follows: In step (1), the temperature of the primary heat treatment was 900°C. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0230] Example 18 The only differences from Example 1 are as follows: In step (1), the temperature of the primary heat treatment was 910°C. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0231] Example 19 The only difference from Example 1 is that lithium aluminate was used instead of Al2O3 in step (2). The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0232] Example 20 The only difference from Example 1 is that titanium oxide was used instead of Al2O3 in step (2). The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0233] Example 21 The only difference from Example 1 is that Li3BO3 was used instead of H3BO3 in step (3). The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0234] Example 22 The only difference from Example 1 is that B2O3 was used instead of H3BO3 in step (3). The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are present as a single crystal particle structure as a whole, that is, distributed in the form of primary particles.

[0235] Example 23 The only difference from Example 1 is that step (3) was not performed. Fig. 25 is a schematic diagram of the high-nickel positive electrode material according to this example. As shown in Fig. 25, only the first coating layer is formed on the surface of the primary particles, and the particles in the positive electrode material as a whole exist in a single-crystal particle structure.

[0236] Example 24 The only difference from Example 1 is that step (2) was not performed. Fig. 26 is a schematic diagram of the high-nickel positive electrode material according to this example. As shown in Fig. 26, only the second coating layer is formed on the surface of the primary particles, and the particles in the positive electrode material as a whole exist in a single-crystal particle structure.

[0237] Example 25 The only difference from Example 1 is the following: Ni was used as the precursor. 0.83 Co 0.12 Mn 0.06 The (OH)2 precursor was chosen. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are distributed as a whole in the form of single crystal particles, i.e., primary particles.

[0238] Example 26 The only difference from Example 1 is the following: Ni was used as the precursor. 0.9 Co 0.05 Mn 0.05 The (OH)2 precursor was chosen. The structure of the high-nickel positive electrode material according to this example is similar to that of Example 1, and the particles in the positive electrode material are distributed as a whole in the form of single crystal particles, i.e., primary particles.

[0239] Comparative Example 1 The only differences from Example 1 are as follows: In step (1), MgO and Al2O3 were used as dopants.

[0240] Comparative Example 2 The only differences from Example 1 are as follows: In step (1), SrO and MgO were used as dopants.

[0241] Comparative Example 3 The only differences from Example 1 are as follows: In step (1), Al2O3 and Y2O3 were used as dopants.

[0242] Comparative Example 4 The only differences from Example 1 are as follows: In step (1), Y2O3 and MgO were used as dopants.

[0243] Comparative Example 5 The only differences from Example 1 are as follows: In step (1), La2O3 and Al2O3 were used as dopants.

[0244] Comparative Example 6 The only differences from Example 1 are as follows: In step (1), ZrO2 and TiO2 were used as dopants.

[0245] Performance evaluation (1) Measurement of alkaline impurities in high-nickel materials The alkaline impurity content on the surface of high-nickel materials can represent the characteristics of the material surface and can be quantitatively measured by analyzing the products of the reaction between the surface and water. When high-nickel material powder is immersed in water, a surface reaction occurs. The reaction increases the pH of the water (due to the dissolution of alkaline impurities), and the alkaline content is quantified by pH titration. The result of the titration is the alkaline impurity content. The alkaline impurity content was measured as follows: 5.0 g of high-nickel material powder was immersed in 100 ml of deionized water and stirred for 10 minutes in a sealed glass flask. After stirring to dissolve the alkali, the aqueous suspension of the powder was filtered to obtain a clarified solution. Then, 0.1 M (mol / L) HCl was added at a rate of 0.5 ml / min while stirring, and the pH curve was recorded. 90 ml of the clarified solution was titrated until the pH reached 3. A reference voltage curve was obtained by titrating a mixture of LiOH and Li2CO3, which are dissolved in deionized water at low concentrations. In most cases, two distinct plateaus were observed. The upper plateau with an endpoint y1 (in ml) between pH 8 and 9 is the value obtained by titration of OH. - / H2O is neutralized first, then CO3 2- / HCO3 - The lower plateau, with an endpoint y2 (in ml) between pH 4 and 6, is formed by the neutralization of HCO3 - The inflection point y1 between the first plateau (upper plateau) and the second plateau (lower plateau) and the inflection point y2 at the end of the second plateau are obtained by the corresponding minimum values ​​of the derivative dpH / dVol of the pH curve. The inflection point y2 generally appears when the pH is close to 4.7. The results are expressed as the following equations (3) and (4) in terms of the weight percentages of LiOH and LiCO3:

number

[0246] (2) XPS measurement of high-nickel positive electrode material X-ray photoelectron spectroscopy (XPS) can analyze a region from the surface of a material to a depth of approximately 5 nm to 10 nm (usually approximately 5 nm), allowing quantitative analysis of the concentration of each element in approximately half of the surface layer. Furthermore, narrow scan analysis can analyze the bonding state of elements. X-ray photoelectron spectroscopy (XPS) was performed using, for example, a ULVAC-PHI X-ray photoelectron spectrometer (Quantera II). Measurement conditions included an X-ray source with an Al monochromator of 100 μm, 25 W, and 15 kV, no surface etching, a photoelectron take-off angle of 45°, and a bond energy correction of the C-C peak of the C1s spectrum at 284.6 eV. XPS measurements were performed on the high-nickel material according to the present disclosure, and the obtained XPS spectrum showed a peak at the Ni bond moiety, Ni2P, appearing in the bond energy range of 850 eV to 870 eV. 3 / 2 Peak separation and curve fitting were performed for Ni 2+ and Ni 3+ The peak area of ​​O1S is calculated, and peak separation and curve fitting are performed for the O1S peak, which appears in the binding energy range of 526 eV to 540 eV. 格子酸素 Peak area and O1S 不純物酸素 The peak area was calculated.

[0247] (3) Establishing standards for battery capacity First, the battery capacity was determined as a reference. The battery was charged to 4.25 V at 1 / 3 C current at room temperature (25°C), allowed to stand for 30 minutes, and then discharged to 2.5 V at 1 / 3 C current, allowed to stand for 30 minutes. This cycle was repeated twice, and the discharge capacity of the second cycle was taken as C0. Subsequent DCIR measurements were based on this.

[0248] (4) DCIR measurement (protection voltage: 1.0V to 4.4V, measurement temperature: 25°C) a. Charged at 10% C0 at a constant current of 0.2 C0 at a temperature of 25°C, allowed to stand for 2 hours (end voltage: V1), and measured for DCIR (discharged at 1.5 C0 for 30 seconds (end voltage: V2), allowed to stand for 30 minutes (end voltage: V3), then charged at 1.5 C0 for 30 seconds (end voltage: V4), allowed to stand for 5 minutes), discharged at 0.33 C0 to 2.5 V / cell, and allowed to stand for 30 minutes. b. Charged at a constant current of 0.2C0 to 20% C0 at a temperature of 25°C, allowed to stand for 2 hours (end voltage: V1), and measured for DCIR (discharged at 1.5C0 for 30 seconds (end voltage: V2), allowed to stand for 30 minutes (end voltage: V3), then charged at 1.5C0 for 30 seconds (end voltage: V4), allowed to stand for 5 minutes), discharged at 0.33C0 to 2.5V / cell, and allowed to stand for 30 minutes. c. Charged to 50% C0 at a constant current of 0.2C0 at a temperature of 25°C, left to rest for 2 hours (end voltage: V1), and measured DCIR (discharged at 1.5C0 for 30 seconds (end voltage: V2), left to rest for 30 minutes (end voltage: V3), then charged at 1.5C0 for 30 seconds (end voltage: V4), left to rest for 5 minutes), discharged to 2.5V / cell at 0.33C0, and left to rest for 30 minutes. d. Charged to 80% C0 at a constant current of 0.2 C0 at a temperature of 25°C, left to stand for 2 hours (end voltage: V1), and measured DCIR (discharged at 1.5 C0 for 30 seconds (end voltage: V2), left to stand for 30 minutes (end voltage: V3), then charged at 1.5 C0 for 30 seconds (end voltage: V4), left to stand for 5 minutes), discharged at 0.33 C0 to 2.5 V / cell, and left to stand for 30 minutes.

[0249] The DCIR values ​​at different SOCs were calculated according to the following equations (5) and (6). DCIR discharge = (V1-V2) / 1.5C0×1000 (unit: mΩ) (5) DCIR charging = (V4-V3) / 1.5C0×1000 (unit: mΩ) (6) The DCIR value after 100 cycles was measured in the same manner as in the measurement of the DCIR before the cycles.

[0250] (5) Thickness expansion measurements were performed on full cells fabricated using high-nickel materials. At room temperature, the battery was charged at a constant current of 0.5 C up to 4.25 V, and then at a constant voltage until the current reached 0.05 C, at which point the battery was fully charged. The initial thickness of the fully charged battery before storage was measured, and the battery was then stored in an oven at 60°C, with the thickness measured every 20 days. The thickness expansion rate of the battery was calculated according to the following equation (7): Thickness expansion rate = (thickness after storage - thickness before storage) / (thickness before storage) (7)

[0251] (6) Cross-section measurements were performed on high-nickel materials after 300 cycles under high-temperature conditions. The high-nickel material was cut using a Hitachi E-3500 ion milling machine after 500 cycles under high-temperature conditions, and the cross-sectional morphology of the high-nickel material was observed using a Hitachi S4800 cold cathode field emission scanning electron microscope.

[0252] (7) pH measurement Measurement method: GB / T 1717-1986 "Measurement of pH value of aqueous pigment suspension" Instrument model number: Mettler Toledo pH meter Brief explanation of the method: A 5.0000±0.0100g sample was taken and placed in a 100ml glass flask, 45g of pure water was added, and the sample was dissolved in the pure water by stirring evenly with a glass rod. After ultrasonic treatment for 5 minutes in an ultrasonic cleaner, the sample was left to stand for 10 minutes before measurement.

[0253] (8) Conductivity measurement Instrument model number: Powder resistivity measuring device Brief description of the method: The depth of the material chamber was set to 10 mm, and the powder sample to be measured was placed into the material chamber using a spatula until the chamber was filled. The sample was flattened, and the pressure was adjusted by turning the handle to 4 MPa, 8 MPa, 12 MPa, 16 MPa, and 20 MPa in sequence. Each pressure was maintained for 5 seconds, and the data was read and recorded.

[0254] (9) Measurement of specific surface area Measurement method: GB / T 19587-2017 "Measurement of solid specific surface area by gas adsorption BET method" Instrument model number: Tristar 3020 specific surface area analyzer Brief explanation of the method: A 3.0000±0.1000g sample was taken and subjected to vacuum degassing at a temperature of 300℃ for 1.0h until the gas was completely removed. After removing the impurities adsorbed on the surface, the specific surface area of ​​the particles was calculated based on the amount of nitrogen gas adsorbed using the nitrogen gas adsorption method.

[0255] (10) Measurement of average particle size Measurement method: GB / T 19077-2016 "Particle size analysis laser diffraction method" Instrument model: Malvern particle size analyzer Brief description of the method: An appropriate amount of sample was placed in a 100 mL flask, water was added, and the sample was subjected to ultrasonic treatment at 240 W for 15 seconds. The sample was then introduced into the sample inlet system in one go to thoroughly disperse the sample to a light blocking rate of 8-15%, and the particle size distribution was measured using the laser diffraction principle.

[0256] 1. XPS measurement and fitting test of high nickel positive electrode material XPS measurement was performed on the high-nickel positive electrode materials prepared in each example and comparative example, and the peak obtained was Ni2P 3 / 2 The area ratio results obtained by peak separation and fitting for O1S and O1S are shown in Table 1 below. 3 / 2 The results of peak separation and fitting for O1S from Example 1, Example 8, Comparative Example 1, and Comparative Example 2 are shown in Figures 3, 4, 5, and 6, respectively. The results of peak separation and fitting for O1S from Example 1, Example 8, Comparative Example 1, and Comparative Example 2 are shown in Figures 7, 8, 9, and 10, respectively.

[0257] [Table 1-1] [Table 1-2]

[0258] With reference to Examples 1 to 26 and Comparative Examples 1 to 6, the high-nickel positive electrode material according to the present disclosure was measured to satisfy the relationships S1 / (S1+S2)>0.5 and 0.9<α / β<1.5. As can be seen from this, Ni was deposited on the surface of the high-nickel material substrate. 3+ The amount of Ni is relatively small. 2+ The amount of Ni is relatively large, which can prevent the surface of the positive electrode material from being oxidized during the desorption of lithium ions, contribute to maintaining the stability of the structure of the positive electrode material, prevent the loss of the positive electrode active material and electrolyte, further increase the capacity of the positive electrode material, and significantly improve the high-temperature cycle performance of the high-nickel positive electrode material. 3+ The amount of Ni is relatively small. 2+ Since the amount of is relatively large, it is possible to suppress the occurrence of cracks inside the material during the charge and discharge process, and the internal structure of the material is stable. As a result, when the positive electrode material according to the present disclosure is used in a battery, the increase in the DC internal resistance of the battery over a long period of cycles is significantly suppressed.

[0259] Ni2P according to Example 1, Example 8, Comparative Example 1, and Comparative Example 2 3 / 2 The results of peak separation and fitting for O1S are shown in Figures 3, 4, 5, and 6, respectively. The results of peak separation and fitting for O1S in Example 1, Example 8, Comparative Example 1, and Comparative Example 2 are shown in Figures 7, 8, 9, and 10. The high-nickel positive electrode material according to the present disclosure has a significantly different area ratio of S1 / (S1+S2) from the material according to the comparative example. The area ratio of S1 / (S1+S2) of the sample in the examples of the present disclosure is greater than 1, meaning that there is Ni on the surface of the material. 2+ The amount of Ni 3+ In contrast, in the comparative example, the area ratio of S1 / (S1+S2) was less than 1, and the amount of O1S 格子酸素 / O1S 不純物酸素The area ratios of the above were almost all greater than 0.5. This shows that the amount of alkaline impurities on the surface of the materials according to the examples was relatively small.

[0260] As can be seen from the measurement of surface alkaline impurities, the total content of alkaline impurities on the surface of the high nickel positive electrode material according to the embodiment of the present disclosure is relatively low, while the total content of alkaline impurities, LiOH and Li2CO3, on the surface of the sample according to the comparative example is relatively high.

[0261] Table 2 shows the results of performance evaluation of high-nickel positive electrode materials according to Examples 1 to 26 and Comparative Examples 1 to 6 of the present disclosure.

[0262] [Table 2-1] [Table 2-2]

[0263] Full cells fabricated using the high-nickel positive electrode materials of Examples 1 to 26 and Comparative Examples 1 to 6 of the present disclosure were cycled 300 times at 1C / 1C under high-temperature conditions of 45°C at different voltages, and then their capacity retention rates were measured. As can be seen from the high-temperature performance measurements, the positive electrode materials of the present disclosure's examples exhibit significantly different high-temperature cycle performance compared to the positive electrode materials of the comparative examples. At 2.5V to 4.2V, the capacity retention rates of some of the positive electrode materials of the present disclosure's examples were approximately 95%, while the capacity retention rates of the positive electrode materials of the comparative examples were 93% or less. When measured at 2.5V to 4.25V, the high-temperature cycle performance of each of the samples of the examples and comparative examples was somewhat reduced due to the presence of a phase transition. However, the high-temperature cycle performance of some of the samples of the examples was still significantly superior to that of the comparative examples.

[0264] The increase in DC internal resistance was measured every 100 cycles for full cells prepared with high-nickel positive electrode materials according to the present disclosure and comparative examples at 2.5V-4.2V, a high temperature of 45°C, and 1C / 1C. Comparative analysis of the differential capacity curves for Example 1, Example 8, Comparative Example 1, and Comparative Example 2 is shown in Figures 11, 12, 13, and 14, respectively. As can be seen from Table 2 and the figures, the increase in DC internal resistance was significantly different between the positive electrode materials according to the present disclosure and the comparative examples, with the increase in DC internal resistance being significantly less for the examples than for the comparative examples. As can be seen from Figures 11, 12, 13, and 14, Example 1 exhibited the smallest irreversible phase transition and the smallest voltage difference ΔV after 300 cycles. This indicates that the structural stability was better when both high and low oxidation states were doped, and the material's surface and internal structure were more stable.

[0265] Full cells were manufactured using the high-nickel positive electrode materials according to the examples and comparative examples of the present disclosure, and the gas generation status of these full cells was measured when stored at a high temperature of 60°C. The thickness of the battery was measured every 20 days, and the thickness expansion rate of the battery was calculated. As can be seen from Table 2, there was a clear difference in the increase in thickness of the batteries of the examples and comparative examples, but the increase in thickness expansion rate of the examples was clearly lower than that of the comparative examples.

[0266] As can be seen from Examples 12 to 18, the cathode material has excellent electrochemical performance when the temperature during the first synthesis of the material is within the range specified in this disclosure. When the temperature of the first heat treatment is lower than the range specified in this disclosure (Example 12) or higher than the range specified in this disclosure (Example 18), there are drawbacks such as poor cycle performance and high expansion coefficient.

[0267] As can be seen from a comparison between Examples 1 to 22 and Example 23, in the examples of the present disclosure, by applying a primary coating to the material and then a secondary coating, alkaline impurities on the material surface can be reduced and the material surface can be protected, reducing gas generation due to decomposition of Li2CO3 in the alkaline impurities on the material surface and gas generation due to side reactions between the alkaline impurities on the material surface and the electrolyte, thereby further improving the cycle performance of the material. The positive electrode material obtained in Example 23 by applying only a primary coating to the substrate material has the disadvantage of inferior cycle performance.

[0268] As can be seen from the comparison between Examples 1 to 22 and Example 24, in the examples of the present disclosure, by applying a secondary coating to the material and then applying a primary coating with an inner layer, the Ni on the surface of the high nickel positive electrode material is balanced by the oxidation number. 2+ The amount of the secondary coating remains unchanged or even increases, thereby improving the stability of the material structure, preventing the generation of alkaline impurities due to contact between the material and water in the air, and reducing gas generation in the material, thereby improving the cycle performance of the material and suppressing the expansion rate of the material. The positive electrode material obtained in Example 24 by applying only the secondary coating to the substrate material has the disadvantages of poor cycle performance and a high expansion rate.

[0269] The high-nickel materials of Examples 1, 8, 25, and 26 and Comparative Examples 1, 2, and 6 were each processed using a cross-section polisher and analyzed after 300 cycles. The cross-sectional analysis results for Examples 1, 8, 25, and 26 are shown in Figures 15, 16, 19, and 20, respectively, and the cross-sectional analysis results for Comparative Examples 1, 2, and 6 are shown in Figures 17, 18, and 21, respectively. Comparing the cross-sectional analysis results of the Examples and Comparative Examples reveals that no cracks were observed within the materials of Examples 1, 8, 25, and 26, whereas cracks were observed within the materials of Comparative Examples 1, 2, and 6. This indicates that doping with both high and low oxidation states, as disclosed herein, can contribute to the stability of the material structure and further improve the cycling performance of the material.

[0270] The above are only representative examples of the present disclosure and are not intended to limit the present disclosure. Those skilled in the art may have various modifications and variations to the present disclosure. As long as they do not deviate from the spirit and principle of the present disclosure, any modifications, equivalent replacements, improvements, etc., fall within the scope of protection of the present disclosure.

[0271] Industrial Applicability The present disclosure provides a high-nickel positive electrode material, a method for preparing the same, and a lithium-ion battery. 3+ The amount of Ni is relatively small. 2+ The amount of is relatively large, which can prevent the surface of the high-nickel positive electrode material from being oxidized during lithium ion desorption, improve the high-temperature cycle performance and structural stability of the high-nickel positive electrode material, prevent the loss of the positive electrode active material and electrolyte, further increase the capacity of the positive electrode material, and significantly improve the high-temperature cycle performance of the high-nickel positive electrode material, and therefore the high-nickel positive electrode material according to the present disclosure has excellent practicality. [Explanation of symbols]

[0272] 100 Cathode Materials 120 particles 122 Primary particles 124 Secondary particles 140 Covering layer 142 1st coating layer 144 Second coating layer

Claims

1. A high-nickel ternary positive electrode material, The general formula of the high-nickel ternary positive electrode material is the following formula (1): Li ｘ Ni １－（ａ＋ｂ＋ｃ＋ｄ＋ｅ＋ｆ） Co ａ M1 ｂ M2 ｃ M3 ｄ M4 ｅ M5 ｆ O ２ (1) However, the following conditions are satisfied: 0.95≦x≦1.2, 0<a≦0.15, 0<b≦0.10, 0<c≦0.05, 0<d≦0.05, 0<e≦0.05, 0<f≦0.05, 0<a+b+c+d+e+f≦0.2; The high-nickel ternary positive electrode material was subjected to XPS measurement of a powder sample using AlKα radiation, and NiP, which appeared in the binding energy range of 850 eV to 870 eV, ３／２ After peak separation and fitting, ２＋ The peak area of ​​Ni is S1. ３＋ The peak area of ​​Ni is S2. ２＋ The half-width of the peak is α, and Ni ３＋ where β is the half-width of the peak, S1, S2, α and β are S1 / (S1+S2)>0.5 and 0.9<α / β<1.5 (2) Fulfilling the relationship, The M1 includes Mn, M2 contains an element having an oxidation number of +4 or more in the high-nickel ternary positive electrode material, M3 contains an element having an oxidation number of +2 in the high-nickel ternary positive electrode material, Each of M2 and M3 contains at least one of Zr, Ti, Nb, Ce, Hf, W, Mo, Ta, Ge, Sn, Sr, Mg, and Ba, and is different from M3; M4 contains an element having an oxidation number of +3 or more in the high-nickel ternary positive electrode material, M4 contains at least one of Al, Ti, P, Si, Nb, Y, W, Cr, Zr, and La, M5 contains at least one of B, La, and Al, M2 and M3 are dopant elements, The high-nickel ternary positive electrode material includes at least one of secondary particles and primary particles, at least a portion of the surface of the primary particles is coated with a coating layer, and the secondary particles include a plurality of primary particles having the coating layer; The M4 and M5 are elements of the coating layer. A high-nickel ternary positive electrode material characterized by:

2. The coating layer is (1) The coating layer includes a first coating layer and a second coating layer, the first coating layer is formed on the surface of the primary particles, and the second coating layer is formed on the surface of the first coating layer; (2) The coating layer includes a first coating layer, and the first coating layer is formed on the surface of the primary particles; (3) The coating layer includes a second coating layer, and the second coating layer is formed on the surface of the primary particles. (4) The coating layer includes a first coating layer and a second coating layer, and the first coating layer includes an element in the high-nickel ternary positive electrode material whose oxidation number is +3 or more; (5) The coating layer includes a first coating layer and a second coating layer, and the first coating layer includes at least one of Al, Ti, P, Si, Nb, Y, W, Cr, Zr, and La; (6) The coating layer includes a first coating layer and a second coating layer, and the first coating layer includes a compound containing at least one of Al, Ti, P, Si, Nb, Y, W, Cr, Zr, and La; (7) The coating layer includes a first coating layer and a second coating layer, the first coating layer includes a compound containing at least one of Al, Ti, P, Si, Nb, Y, W, Cr, Zr, and La, and the compound is at least one of an oxide, a hydroxide, or a salt. (8) The coating layer includes a first coating layer and a second coating layer, and the second coating layer includes a compound containing at least one of B, La, and Al; (9) The coating layer includes a first coating layer and a second coating layer, the second coating layer includes a compound containing at least one of B, La, and Al, and the compound includes at least one of an oxide, an acid, and a lithium-containing salt; (10) The coating layer includes a first coating layer and a second coating layer, the second coating layer includes a boron-containing compound, and the boron-containing compound includes at least one of a boron-containing oxide, a boron-containing acid, and a salt containing boron and lithium; (11) The coating layer includes a first coating layer and a second coating layer, the second coating layer includes a boron-containing compound, and the boron-containing compound is B ２ O ３ , H ３ BO ３ , Li ２ Alumni ２ O ３ , Li ３ BO ３ , Li ２ B ４ O ７ , Li ２ B ２ O ７ and Li ２ B ８ O １３ containing at least one of The present invention has at least one of the following characteristics (1) to (11):

2. The high-nickel ternary positive electrode material according to claim 1.

3. (1) XPS measurement of a powder sample of the high-nickel ternary positive electrode material is performed using AlKα radiation, and NiP appears in the binding energy range of 850 eV to 870 eV. ３／２ After peak separation and fitting, ２＋ / Ni ３＋ The area ratio is greater than 1; (2) XPS measurement of a powder sample of the high-nickel ternary positive electrode material is performed using AlKα radiation, and the O1S peak that appears in the binding energy range of 526 eV to 540 eV is subjected to peak separation and fitting. 格子酸素 / O1S 不純物酸素 The area ratio is more than 1 / 2, (3) The mass fraction of LiOH in the high-nickel ternary positive electrode material is less than 0.3 wt %; (4) In the high-nickel ternary positive electrode material, Li ２ CO ３ the mass fraction of is less than 0.3 wt %; (5) The crystal structure of the high-nickel ternary positive electrode material is a hexagonal or monoclinic crystal structure; (6) The shape of the crystal particles of the high-nickel ternary positive electrode material includes at least one of a substantially spherical shape, a substantially cubic shape, and a substantially rectangular shape; (7) The pH of the high-nickel ternary positive electrode material is 10<pH<12; (8) The pH of the high-nickel ternary positive electrode material is 10.5<pH<11.7; (9) The powder conductivity of the high-nickel ternary positive electrode material is greater than 0.02 S / cm; (10) The specific surface area of ​​the high-nickel ternary positive electrode material is 0.3 m ２ / g to 0.8m ２ / g, (11) The average particle size of the high-nickel ternary positive electrode material is 2.5 μm to 4.5 μm; The present invention has at least one of the following characteristics (1) to (11):

3. The high-nickel ternary positive electrode material according to claim 1 or 2.

4. A step of mixing a metal composite hydroxide precursor, a lithium-containing compound, and a dopant, and subjecting the mixture to a primary heat treatment to obtain a substrate material; and applying a coating to the substrate material to obtain a high-nickel ternary positive electrode material; the dopant includes a compound containing an M2 element and a compound containing an M3 element, the compound containing the M2 element being at least one of an oxide, a hydroxide, and a lithium metal oxide containing the M2 element, and the M2 element in the compound has an oxidation number of +4 or more; the compound containing the M3 element being at least one of an oxide and a hydroxide containing the M3 element, and the M3 element in the compound has an oxidation number of +2; each of the M2 element and the M3 element includes at least one of Zr, Ti, Nb, Ce, Hf, W, Mo, Ta, Ge, Sn, Sr, Mg, and Ba, and is different from the M2 element and the M3 element; In the dopant, the molar ratio n Ｍ２ :n Ｍ３ is greater than or equal to 2:1, The general formula of the high-nickel ternary positive electrode material is the following formula (1): Li x Ni 1-(a+b+c+d+e+f) Co a M1 b M2 c M3 d M4 e M5 f O 2 (1) However, the following conditions are satisfied: 0.95≦x≦1.2, 0<a≦0.15, 0<b≦0.10, 0<c≦0.05, 0<d≦0.05, 0<e≦0.05, 0<f≦0.05, 0<a+b+c+d+e+f≦0.2; XPS measurement of a powder sample of the high-nickel ternary positive electrode material was performed using AlKα radiation, and peak separation and fitting were performed on the Ni2P 3 / 2 peak appearing in the binding energy range of 850 eV to 870 eV. After that, the peak area of ​​Ni 2+ was defined as S1, the peak area of ​​Ni 3+ was defined as S2, the half-width of the Ni 2+ peak was defined as α, and the half-width of the Ni 3+ peak was defined as β, and S1, S2, α, and β were defined as follows: S1 / (S1+S2)>0.5 and 0.9<α / β<1.5 (2) Fulfilling the relationship, The M1 includes Mn, M2 contains an element having an oxidation number of +4 or more in the high-nickel ternary positive electrode material, M3 contains an element having an oxidation number of +2 in the high-nickel ternary positive electrode material, Each of M2 and M3 contains at least one of Zr, Ti, Nb, Ce, Hf, W, Mo, Ta, Ge, Sn, Sr, Mg, and Ba, and is different from M3; M4 contains an element having an oxidation number of +3 or more in the high-nickel ternary positive electrode material, M4 contains at least one of Al, Ti, P, Si, Nb, Y, W, Cr, Zr, and La, The M5 contains at least one of B, La, and Al. A method for preparing a high-nickel ternary positive electrode material.

5. (1) the mass ratio of the metal composite hydroxide precursor to the lithium-containing compound to the dopant is 1:(0.46 to 0.49):(0.001 to 0.005); (2) the mass ratio of the metal composite hydroxide precursor to the lithium-containing compound to the dopant is 1:(0.46 to 0.48):(0.001 to 0.003); (3) the atomic ratio of the total number of metal atoms Me in the metal composite hydroxide precursor to the number of Li atoms in the lithium-containing compound is 1.0<Li / Me<1.2; (4) The lithium-containing compound includes a lithium-containing salt and a lithium-containing hydroxide; (5) The lithium-containing compound includes at least one of lithium carbonate, lithium hydroxide, lithium nitrate, and lithium acetate; (6) The average particle size of the dopant is 10 nm to 50 nm; (7) The temperature of the primary heat treatment is 680°C to 900°C; (8) The duration of the primary heat treatment is 5 hours to 20 hours. (9) The temperature rising rate of the primary heat treatment is 50°C / h to 550°C / h; (10) The oxygen content in the substrate material is 85% or more; The present invention has at least one of the following characteristics (1) to (10):

5. The method of claim 4.

6. The preparation method includes a step of mixing the substrate material with a first coating agent and subjecting the mixture to a secondary heat treatment to obtain a primary coating product; The preparation method comprises: (1) The mass ratio of the substrate material to the first coating material is 1000:(0.5 to 3); (2) The first coating agent contains a metal element or a nonmetal element having an oxidation number of +3 or more; (3) The first coating agent contains at least one of an oxide, a salt, or a hydroxide of a metal element or a nonmetal element having an oxidation number of +3 or more; (4) The first coating agent contains a metal element or a nonmetal element having an oxidation number of +3 or more, and the metal element or the nonmetal element contains at least one of Al, Ti, P, Si, Nb, Y, W, Cr, Zr, and La; (5) The first coating agent contains at least one of lithium aluminate, lithium titanate, lanthanum lithium titanate, yttrium oxide, aluminum oxide, and titanium oxide; (6) The average particle size of the first coating agent is 10 nm to 50 nm; (7) The temperature of the secondary heat treatment is 600°C to 800°C; (8) The time for the secondary heat treatment is 1 hour to 20 hours; (9) The temperature rising rate of the secondary heat treatment is 50°C / h to 550°C / h; (10) After the secondary heat treatment, the method further includes a step of washing under a constant temperature condition, and then drying under a vacuum condition after washing, wherein the temperature of the constant temperature condition is 10°C to 25°C; (11) After the secondary heat treatment, the method further includes a step of washing under a constant temperature condition, and then drying under a vacuum condition after washing, and the temperature of the drying treatment is 100°C to 200°C; (12) The oxygen content in the primary coating product is 85% or more; The present invention has at least one of the following characteristics (1) to (12):

5. The method of claim 4.

7. The preparation method further includes a step of mixing the primary coating product with a second coating agent and subjecting the mixture to a third heat treatment; The preparation method comprises: (1) The second coating agent contains a compound containing at least one of B, La, and Al; (2) The second coating agent includes a compound containing at least one of B, La, and Al, and the compound is an oxide, an acid, or a lithium-containing salt; (3) The second coating agent contains a boron-containing compound; (4) The second coating agent includes a boron-containing compound, and the boron-containing compound includes a boron-containing oxide, a boron-containing acid, or a salt containing boron and lithium; (5) The second coating agent contains a boron-containing compound, and the boron-containing compound is B ２ O ３ , H ３ BO ３ , Li ２ Alumni ２ O ３ , Li ３ BO ３ , Li ２ B ４ O ７ , Li ２ B ２ O ７ and Li ２ B ８ O １３ containing at least one of (6) The mass ratio of the primary coating product to the second coating agent is 1:(0.0005-0.005); (7) The temperature of the third heat treatment is 200°C to 600°C; (8) The time for the third heat treatment is 1 hour to 20 hours. (9) The temperature rising rate of the tertiary heat treatment is 50°C / h to 550°C / h; The present invention has at least one of the following characteristics (1) to (9):

7. The method of claim 6.

8. The metal composite hydroxide precursor is obtained by subjecting a metal salt solution, a complexing agent, and a pH adjuster to a mixing treatment. The preparation method according to any one of claims 4 to 7.

9. (1) the mass ratio of the metal salt solution to the complexing agent to the pH adjuster is 1:(0.01-0.10):(0.1-0.8); (2) The metal salt solution includes at least one of a nickel salt solution, a cobalt salt solution, a manganese salt solution, and an aluminum salt solution; (3) The complexing agent contains at least one of ammonia water, ammonium sulfate, ammonium chloride, ammonium carbonate, ammonium fluoride, hydrazine, ethylenediaminetetraacetic acid, nitrilotriacetic acid, uracildiacetic acid, and glycine; (4) The pH adjuster contains at least one of sodium hydroxide and potassium hydroxide; (5) The pH of the mixing treatment is 9 to 13; (6) The temperature of the mixing treatment is 10°C to 80°C; (7) The duration of the mixing treatment is 10 hours to 200 hours; (8) The mixing treatment is carried out in a stirring state, and the stirring speed is 800 rpm to 1200 rpm; (9) After the mixing treatment, the process includes steps of solid-liquid separation, washing, and drying; (10) The average particle size of the metal composite hydroxide precursor is 3 μm to 10 μm; The present invention has at least one of the following characteristics (1) to (10):

9. The method of claim 8.

10. The high-nickel ternary positive electrode material according to claim 1 or 2 is included. A lithium-ion battery characterized by:

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