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

Abstract

This application relates to a high-nickel cathode material and its preparation method, and a lithium-ion battery. The chemical formula of the high-nickel cathode material is Li. σ Ni a Co b Mn c M1 x M2 y M3 z O 2+α Wherein, 0.80<σ<1.20, a+b+c+x+y+z=1, 0.7<a<1.0, 0<b<0.05, 0<c<0.3, 0<x<0.3, 0<y<0.3, 0<z<0.3, 0<α<0.1, M1, M2, and M3 are each independently including at least one of Al, Co, Zr, Ti, Mg, Y, La, Sr, Ba, W, Mo, Nb, and Si, and M1, M2, and M3 are all different; the high-nickel cathode material includes a high-nickel material matrix and a coating layer. Cu-Kα rays are used to perform XRD measurements on the high-nickel material matrix and the high-nickel cathode material, respectively. The intensity of the (104) diffraction peak appearing in the diffraction angle range of 44-45° is recorded as I. b (High-nickel material matrix) and I c (High-nickel cathode material), the unit of diffraction peak intensity is counts, let the diffraction peak intensity difference P = I c -I b 0 < P < 1000. The high-nickel cathode material provided in this application has better high-temperature cycling performance and a low DC internal resistance growth rate.

Description

Technical Field

[0001] This invention belongs to the field of cathode material technology, and particularly relates to a high-nickel cathode material and its preparation method, and lithium-ion batteries. Background Technology

[0002] Lithium-ion batteries are widely used in laptops, mobile phones, and digital products due to their high energy density, good safety performance, long cycle life, and environmental friendliness. Simultaneously, with increasing environmental awareness, lithium-ion batteries are gradually being used as power batteries in transportation vehicles, such as electric vehicles and electric buses. The market is placing increasingly higher demands on the specific capacity, energy density, power density, and lifespan of lithium-ion batteries, especially specific capacity. The most commonly used cathode materials in lithium-ion batteries are olivine-structured LiFePO4, layered LiCoO2, and layered lithium nickel oxide materials. Olivine-structured LiFePO4 has reached its capacity limit and its main applications are in energy storage and low-range electric vehicles. Layered LiCoO2 is mainly used in consumer batteries. Lithium nickel oxide materials are widely used in electric vehicles. In lithium nickel oxide materials, nickel is the main redox reaction element; increasing the nickel content can effectively improve the specific capacity of these materials, thus the development of high-nickel materials has become a market trend.

[0003] The main factors currently hindering the widespread application of high-nickel ternary materials in power batteries are poor high-temperature performance, rapid increase in DC internal resistance, and gas production. These unfavorable factors are mainly caused by three factors. Firstly, the intrinsic structure of high-nickel ternary materials undergoes irreversible structural changes during charging and discharging, with higher nickel content resulting in greater structural changes. Secondly, during charging and discharging, the valence of nickel changes accordingly, corresponding to the extraction and insertion of lithium ions. Under the same voltage, higher nickel content results in more lithium ions being extracted, leading to greater volume changes in the material. These volume changes are accompanied by the release of internal stress, causing cracks in the high-nickel material. Especially for high-nickel materials in the charging state, the electrolyte can enter the material through these cracks, reacting with the highly active Ni... 4+ Redox reactions occur, leading to changes in the material structure; secondly, when high-nickel ternary materials undergo delithiation, the Ni on the material surface... 3+ It will be converted into Ni, a strong oxidizing agent. 4+ Ni 4+High-nickel ternary materials readily undergo redox reactions with organic electrolytes, leading to the loss of positive electrode active material and electrolyte, resulting in capacity decay, increased DC internal resistance, and gas generation. Finally, high-nickel ternary materials are prone to generating alkaline impurities (including residual Li₂CO₃ and LiOH on the material surface) during synthesis. These alkaline impurities are non-conductive and readily react with the electrolyte, causing gas generation and battery polarization. Currently, high-temperature solid-phase coating is the main method for improving high-nickel materials, but mastering high-temperature solid-phase coating is crucial. NCM ternary cathode materials can be broadly understood as LiCoO₂ and LiNi... 0.5 Mn 0.5 A solid solution of O2 and LiNiO2, corresponding to the general formula Li 1+a [Ni z (Ni 1 / 2 Mn 1 / 2 ) y CO x ] 1-a O2, where Z represents the proportion of LiNiO2; a larger Z indicates a higher LiNiO2 content in the material. LiNiO2 itself has poor high-temperature stability. According to literature reports, LiNiO2 undergoes the following decomposition reaction at certain temperatures:

[0004] 650-720℃ LiNiO2(s)=Li2Ni8O 10 (s) + 3Li₂O(s) + 3 / 2O₂(g)

[0005] It is evident that excessively high coating temperatures can lead to the decomposition of LiNiO2 in high-nickel materials, generating impurity phases and affecting the high-temperature performance and DC internal resistance of the materials. However, excessively low temperatures can result in uneven coating and coating layer detachment. Therefore, during the high-temperature solid-phase coating process, it is necessary to improve the uniformity of the coating layer and the tightness of the bonding between the coating layer and the substrate, while ensuring that the structure of the substrate itself is not affected during the high-temperature coating process.

[0006] Currently, high-temperature solid-phase coating is the main method for improving high-nickel materials, but how to achieve a good high-temperature solid-phase coating is crucial. LiNiO2 in ternary cathode materials has poor high-temperature stability; excessively high coating temperatures can cause LiNiO2 to decompose, generating impurity phases and affecting the material's high-temperature performance and DC internal resistance. However, excessively low temperatures can lead to uneven coating and coating detachment. Therefore, improving the uniformity of the coating and the tightness of its bonding with the substrate material without affecting the structure of the base material is a pressing issue that needs to be addressed. Summary of the Invention

[0007] The purpose of this application is to provide a high-nickel cathode material and its preparation method, as well as a lithium-ion battery. The coating layer on the surface of the high-nickel cathode material of this application can be tightly bonded to the active material, which can prevent the surface of the high-nickel cathode material from being oxidized during delithiation, thereby improving the high-temperature cycle performance and structural stability of the high-nickel cathode material.

[0008] Firstly, this application discloses a high-nickel cathode material, wherein the chemical formula of the high-nickel cathode material is Li. σ Ni a Co b Mn c M1 x M2 y M3 z O 2+α Wherein, 0.80<σ<1.20, a+b+c+x+y+z=1, 0.7<a<1.0, 0<b<0.05, 0<c<0.3, 0<x<0.3, 0<y<0.3, 0<z<0.3, 0<α<0.1, M1, M2, and M3 are each independently selected from at least one of Al, Co, Zr, Ti, Mg, Y, La, Sr, Ba, W, Mo, Nb, and Si, and M1, M2, and M3 are all different; the high-nickel cathode material includes a high-nickel material matrix and a coating layer. Cu-Kα rays are used to perform XRD measurements on the high-nickel material matrix and the high-nickel cathode material, respectively. The intensity of the (104) diffraction peak appearing in the diffraction angle range of 44-45° is denoted as I. b (High-nickel material matrix) and I c (High-nickel cathode material), the unit of diffraction peak intensity is counts, let the diffraction peak intensity difference P = I c -I b , 0 < P < 1000.

[0009] Secondly, this application discloses a high-nickel cathode material, wherein the chemical formula of the high-nickel cathode material is Li. σ Ni a Co b Mn c M1 x M2 y M3 z O 2+αWherein, 0.80 < σ < 1.20, a + b + c + x + y + z = 1, 0.7 < a < 1.0, 0 < b < 0.05, 0 < c < 0.3, 0 < x < 0.3, 0 < y < 0.3, 0 < z < 0.3, 0 < α < 0.1, M1, M2, and M3 are each independently selected from at least one of Al, Co, Zr, Ti, Mg, Y, La, Sr, Ba, W, Mo, Nb, and Si, and M1, M2, and M3 are all different; the high-nickel cathode material includes a high-nickel material matrix and a coating layer at least partially located in the high-nickel material matrix, and the surface region of the high-nickel cathode material is measured by Al-Kα radiation using powder XPS, and the surface region of the high-nickel cathode material contains Ni. 2+ and Ni 3+ Ni 2+ molar content of Ni 3+ The ratio of the molar content of the components is set as Q, where 0.5 < Q < 3.

[0010] In some feasible implementations, the surface region of the high-nickel cathode material refers to the region from the high-nickel surface to the center, which is 5nm to 10nm in diameter.

[0011] In some feasible embodiments, the chemical formula of the high-nickel material matrix is ​​Li. σ Ni a Co b Mn c M1 x O 2+α . 0.80<σ<1.20, 0.7<a<1.0, 0<b<0.05, 0<c<0.3, 0<x<0.3, 0<α<0.1.

[0012] In some feasible implementations, a first coating layer is formed on the surface of a high-nickel material substrate, and a second coating layer is formed on the surface of the first coating layer.

[0013] In some feasible implementations, the first coating layer comprises an oxide of M2 and a lithium compound containing M2.

[0014] In some feasible embodiments, the second coating layer comprises an oxide of M3 and a lithium compound containing M3.

[0015] In some feasible implementations, the thickness of the first coating layer is 5 nm to 50 nm.

[0016] In some feasible implementations, the thickness of the second coating layer is 5 nm to 50 nm.

[0017] In some feasible embodiments, the high-nickel cathode material is subjected to powder XPS analysis using Al-Kα rays, and the surface of the high-nickel cathode material contains Ni.2+ Ni 2+ The molar content is 50 mol% to 70 mol%.

[0018] In some feasible embodiments, the high-nickel cathode material is subjected to powder XPS analysis using Al-Kα rays, and the surface of the high-nickel cathode material contains Ni. 3+ Ni 3+ The molar content is 30 mol% to 50 mol%.

[0019] In some feasible implementations, the LiOH content in the high-nickel cathode material is less than 0.3 wt%.

[0020] In some feasible implementations, the mass content of Li2CO3 in the high-nickel cathode material is less than 0.3 wt%.

[0021] In some feasible implementations, the crystal structure of the high-nickel cathode material is a hexagonal crystal structure or a monoclinic crystal structure.

[0022] In some feasible implementations, the powder conductivity of the high-nickel cathode material is greater than 0.02 S / cm.

[0023] In some feasible embodiments, the specific surface area of ​​the high-nickel cathode material is 0.3 m². 2 / g~0.8m 2 / g.

[0024] In some feasible embodiments, the particle size D50 of the high-nickel cathode material is 2.5 μm to 4.5 μm.

[0025] Thirdly, this application provides a method for preparing a high-nickel cathode material, comprising the following steps:

[0026] A mixed solution containing a metal composite hydroxide precursor, a dopant containing M1 element, and a lithium compound is dried, and the dried product is subjected to a single heat treatment to obtain the matrix material.

[0027] The matrix material is mixed with a first coating agent containing M2 element and then subjected to a second heat treatment to obtain the first coated product. The temperature of the second heat treatment is T℃, where T = 700-10n. M1 / 1000, n M1 This indicates the total doping amount of element M1 in the matrix material;

[0028] The material obtained from the first coating is mixed with a second coating agent containing element M3 and then subjected to three heat treatments to obtain a high-nickel cathode material; wherein M1, M2, and M3 are each independently selected from at least one of Al, Co, Zr, Ti, Mg, Y, La, Sr, Ba, W, Mo, Nb, and Si, and M1, M2, and M3 are all different.

[0029] In some feasible embodiments, the molar ratio of the metal composite hydroxide precursor, the dopant containing element M1, and the lithium-containing compound is 1:(0-0.3):(1.0-1.2).

[0030] In some feasible embodiments, the molar ratio of the total metal Me in the metal composite hydroxide precursor to Li in the lithium-containing compound is 1.0 < Li / Me < 1.1.

[0031] In some feasible implementations, the lithium-containing compound includes lithium hydroxide.

[0032] In some feasible embodiments, the lithium-containing compound is lithium hydroxide, which includes at least one of anhydrous lithium hydroxide and lithium hydroxide monohydrate.

[0033] In some feasible implementations, the mixed solution includes a solvent, wherein the solvent is deionized water.

[0034] In some feasible embodiments, the general chemical formula of the metal composite hydroxide precursor is Ni. a Co b Mn c (OH)2, where 0.7 < a < 1.0, 0.0 < b < 0.05, and 0.0 < c < 0.3.

[0035] In some feasible embodiments, the concentration of the lithium-containing compound in the mixed solution is 6 mol / L to 8 mol / L;

[0036] In some feasible implementations, the mixed solution also includes an oxidizing agent.

[0037] In some feasible embodiments, the mixed solution further includes an oxidant selected from at least one of hydrogen peroxide, ozone, oxygen, air, hypochlorite, and chlorate.

[0038] In some feasible implementations, the amount of M1 element added is 0 to 0.3% of the total molar amount of the matrix material.

[0039] In some feasible implementations, the heating temperature of the mixed solution is 90°C to 100°C.

[0040] In some feasible implementations, the heating time of the mixed solution is 1h to 10h.

[0041] In some feasible embodiments, the stirring speed of the mixed solution is 100 r / min to 800 r / min.

[0042] In some feasible implementations, the drying method is spray drying, wherein the inlet temperature of the spray dryer is 150℃~350℃ and the outlet temperature is 100℃~150℃.

[0043] In some feasible implementations, the primary heat treatment is a staged heat treatment.

[0044] In some feasible embodiments, the primary heat treatment includes heating to 400-600°C at a heating rate of 1-6°C / min and holding at that temperature for 1-4 hours, followed by heating to 700-900°C at a heating rate of 1-6°C / min and holding at that temperature for 10-20 hours.

[0045] In some feasible embodiments, the primary heat treatment includes heating to 500-550°C at a heating rate of 1-6°C / min and holding at that temperature for 2-3 hours, followed by heating to 750-850°C at a heating rate of 1-6°C / min and holding at that temperature for 10-14 hours.

[0046] In some feasible embodiments, the mass content of residual lithium on the surface of the matrix material is <4000 ppm;

[0047] In some feasible embodiments, the specific surface area of ​​the matrix material is 0.4 m². 2 / g~1.0m 2 / g.

[0048] In some feasible embodiments, the first coating agent is selected from at least one of the oxides of M2 and the hydroxides of M2.

[0049] In some feasible embodiments, the amount of the first coating agent added is 10,000 ppm to 50,000 ppm by mass of the matrix material.

[0050] In some feasible implementations, the secondary heat treatment time is 1 hour to 10 hours.

[0051] In some feasible implementations, the heating rate of the secondary heat treatment is 1℃ / min to 6℃ / min.

[0052] In some feasible implementations, the secondary heat treatment is carried out in an oxygen-containing atmosphere with an oxygen concentration of ≥90%.

[0053] In some feasible implementations, the surface residual lithium content of the coating obtained in a single coating is ≤1500ppm.

[0054] In some feasible implementations, the specific surface area of ​​the material obtained from the single coating is 0.4 m². 2 / g~0.8m 2 / g.

[0055] In some feasible implementations, the pH value of the one-time coating is <11.5.

[0056] In some feasible embodiments, the second coating agent is selected from at least one of the oxides of M3 and lithium-containing compounds.

[0057] In some feasible embodiments, the amount of the second coating agent added is 10,000 ppm to 50,000 ppm by mass of the matrix material.

[0058] In some feasible implementations, the temperature of the three heat treatments is 200°C to 400°C.

[0059] In some feasible implementations, the duration of the three heat treatments is 5 to 12 hours.

[0060] In some feasible implementations, the heating rate of the three heat treatments is 1°C / min to 6°C / min.

[0061] In some feasible implementations, the three heat treatments are carried out in an oxygen-containing atmosphere with an oxygen concentration of ≥90%.

[0062] In some feasible embodiments, the high-nickel cathode material comprises a high-nickel material matrix and a coating layer. Cu-Kα radiation is used to perform XRD measurements on the high-nickel material matrix and the high-nickel cathode material, respectively. The intensities of the (104) diffraction peaks appearing in the diffraction angle range of 44-45° are denoted as I. b (High-nickel material matrix) and I c (High-nickel cathode material), the unit of diffraction peak intensity is counts, let the diffraction peak intensity difference x = I c -I b , 0 < x < 1000.

[0063] In some feasible embodiments, the high-nickel cathode material is subjected to powder XPS analysis using Al-Kα rays, and the surface of the high-nickel cathode material contains Ni. 2+ Ni 2+ The molar content is 50 mol% to 70 mol%.

[0064] In some feasible embodiments, the high-nickel cathode material is subjected to powder XPS analysis using Al-Kα rays, and the surface of the high-nickel cathode material contains Ni. 3+ Ni 3+ The molar content is 30 mol% to 50 mol%.

[0065] In some feasible implementations, the LiOH content in the high-nickel cathode material is less than 0.3 wt%.

[0066] In some feasible implementations, the mass content of Li2CO3 in the high-nickel cathode material is less than 0.3 wt%.

[0067] In some feasible implementations, the crystal structure of the high-nickel cathode material is a hexagonal crystal structure or a monoclinic crystal structure.

[0068] In some feasible implementations, the powder conductivity of the high-nickel cathode material is greater than 0.02 S / cm.

[0069] In some feasible embodiments, the specific surface area of ​​the high-nickel cathode material is 0.3 m². 2 / g~0.8m 2 / g.

[0070] In some feasible embodiments, the particle size D50 of the high-nickel cathode material is 2.5 μm to 4.5 μm.

[0071] Thirdly, this application provides a lithium-ion battery, the lithium-ion battery comprising the high-nickel cathode material described in the first aspect or the high-nickel cathode material prepared by the method described in the second aspect.

[0072] Compared with the prior art, the present invention has the following advantages:

[0073] The high-nickel cathode material provided in this application is analyzed by Cu-Kα XRD to determine the diffraction peak intensity of the substrate and the coating layer. By controlling the difference in diffraction peak intensity between the substrate and the coating layer, the coating layer is tightly bonded to the substrate, which helps maintain the stability of the cathode material structure, prevents the coating layer from falling off the substrate surface during charging and discharging, avoids capacity loss of the cathode material, and also improves the high-temperature cycling performance of the material.

[0074] The preparation method provided in this application involves mixing a precursor, dopant, and lithium-containing compound in a mixed solution, followed by drying and a first heat treatment to obtain a matrix material. This matrix material is then mixed with a first coating agent and subjected to a second heat treatment. During the second heat treatment, the heat treatment temperature is controlled; the higher the M1 doping content in the matrix material, the higher the second heat treatment temperature. By rationally controlling the heat treatment temperature, the bonding strength between the coating layer and the matrix material can be effectively improved, thereby enhancing the stability of the cathode material structure. The material obtained from the first coating is then mixed with a second coating agent and subjected to a third heat treatment, resulting in a tight bond between the coating layer and the matrix material of the high-nickel cathode material, reducing residual lithium on the material surface. Through multiple heat treatments, the formation of Li2Ni8O on the material surface can be suppressed. 10 Impurity phases are generated, which improves the performance of the material. At the same time, high-nickel cathode materials do not require water washing, which shortens the material preparation process and increases production capacity. Attached Figure Description

[0075] To more clearly illustrate the technical solutions of the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0076] Figure 1 This is a schematic flowchart illustrating the preparation method of the high-nickel cathode material provided in the embodiments of this application.

[0077] Figure 2 This is a SEM image of the matrix material prepared in Example 1 of this application.

[0078] Figure 3 This is a SEM image of the high-nickel cathode material prepared in Example 1 of this application.

[0079] Figure 4 This is a SEM image of the high-nickel cathode material prepared in Example 2 of this application.

[0080] Figure 5 This is a SEM image of the cathode material prepared in Comparative Example 1 of this application.

[0081] Figure 6 The image shows the XRD pattern of the high-nickel cathode material prepared in Example 1 of this application.

[0082] Figure 7 The image shows the XRD pattern of the high-nickel cathode material prepared in Example 2 of this application.

[0083] Figure 8 The image shows the XRD pattern of the high-nickel cathode material prepared in Comparative Example 1 of this application.

[0084] Figure 9 The image shows the XRD pattern of the high-nickel cathode material prepared in Comparative Example 2 of this application. Detailed Implementation

[0085] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0086] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0087] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0088] For ease of understanding of this invention, specific terms have been appropriately defined in this application. Unless otherwise defined herein, the scientific and technical terms used in this invention have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains.

[0089] As used herein, the term "matrix" refers to a lithium-based composite oxide synthesized by a high-temperature solid-state reaction of a precursor and a lithium salt, and includes both lithium and metal elements.

[0090] As used in this article, the term "primary particle" refers to a particle that exists alone and does not form a condensate.

[0091] As used in this article, the term "secondary particle" refers to a particle formed by the condensation of the aforementioned primary particles.

[0092] NCM ternary cathode materials can be understood as LiCoO2, LiNi 0.5 Mn 0.5 A solid solution of O2 and LiNiO2, corresponding to the general formula Li 1+a [Ni z (Ni 1 / 2 Mn 1 / 2 ) y CO x ] 1-a O2, where Z represents the proportion of LiNiO2; a larger Z indicates a higher content of LiNiO2 in the material. LiNiO2 itself has poor high-temperature stability. According to literature reports, LiNiO2 undergoes the following decomposition reaction at certain temperatures:

[0093] 650℃~720℃LiNiO2(s)=Li2Ni8O 10(S) + 3Li₂O(s) + 3 / 2O₂(g)

[0094] 850℃~950℃ Li2Ni8O 10 (s)=2Li2O(s)+16NiO(s)+O2(g)

[0095] Currently, most ternary materials are coated using a high-temperature solid-state coating method. The high-temperature solid-state coating temperature is generally between 500-800℃. Too low a temperature can lead to uneven coating and coating detachment, while too high a temperature can cause the LiNiO2 in high-nickel materials to decompose, generating impurity phases and affecting the material's high-temperature performance and increasing DC internal resistance. Therefore, in the high-temperature solid-state coating process, it is necessary to improve the uniformity of the coating layer and the tightness of the bond between the coating layer and the substrate, while ensuring that the structure of the substrate itself remains unaffected during the high-temperature coating process.

[0096] Therefore, this application provides a high-nickel cathode material, the general chemical formula of which is Li. σ Ni a Co b Mn c M1 x M2 y M3 z O 2+α Wherein, 0.80<σ<1.20, a+b+c+x+y+z=1, 0.7<a<1.0, 0<b<0.05, 0<c<0.3, 0<x<0.3, 0<y<0.3, 0<z<0.3, 0<α<0.1, M1, M2, and M3 are each independently including at least one of Al, Co, Zr, Ti, Mg, Y, La, Sr, Ba, W, Mo, Nb, and Si, and M1, M2, and M3 are all different; the high-nickel cathode material includes a high-nickel material matrix and a coating layer. The high-nickel material matrix and the high-nickel cathode material (the material after coating the high-nickel material matrix) are XRD measured by Cu-Kα radiation. The intensity of the (104) diffraction peak appearing in the diffraction angle range of 44-45° is recorded as I. b (High-nickel material matrix) and I c (High-nickel cathode material), diffraction peak intensity unit is counts, let the diffraction peak intensity difference P = I c -I b P represents the intensity difference of the (104) diffraction peak between the matrix and the high-nickel cathode material, where 0 counts < P < 1000 counts, and more preferably 0 counts < P < 500 counts.

[0097] One embodiment of the high-nickel cathode material was analyzed by Al-Kα radiation using powder XPS, wherein the surface region of the high-nickel cathode material contains Ni. 2+ and Ni 3+Ni 2+ molar percentage content of Ni 3+ The ratio of the molar percentage content is denoted as P, where 0.5 < Q < 3, more preferably 0.5 < Q < 1.5; the specific value of Q can be 0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.5, 1.7, 1.9, 2.1, 2.3, 2.5, 2.7, or 2.99, etc., and is not limited here. The smaller the value of P, the smaller the value of Q, indicating that the material has better high-temperature cycling performance and a lower DC internal resistance growth rate.

[0098] In some implementations, the surface region of the high-nickel cathode material refers to the region from the high-nickel surface to the center, which is 5 nm to 10 nm in diameter.

[0099] In some embodiments, the cathode material includes secondary particles and / or primary particles, with at least a portion of the surface of the primary particles coated with a coating layer, and the secondary particles including a plurality of primary particles with coating layers. It is understood that the secondary particles are aggregates of a plurality of primary particles, and the cathode material of this application may include only primary particles, or only secondary particles, or may be a mixture of primary and secondary particles.

[0100] In some embodiments, the coating layer includes a first coating layer and a second coating layer, wherein 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. The first coating layer can improve the stability of the material surface structure, and the second coating layer can effectively improve the material's processability and electrical conductivity.

[0101] In some embodiments, the first coating layer comprises an oxide of M2, wherein M2 comprises at least one selected from Al, Co, Zr, Ti, Mg, Y, La, Sr, Ba, W, Mo, Nb, and Si, and the oxidation state of the aforementioned elements in the high-nickel cathode material is greater than or equal to +3, thereby increasing the Ni content of the surface layer of the high-nickel cathode material. 2+ The quantity remains constant or is further increased to improve the stability of the cathode material structure, while also reducing the formation of alkaline impurities on the material surface. The first coating layer may also include a lithium compound containing M2, specifically, the lithium compound may include at least one of LiAlO2 and Li2ZrO3.

[0102] Understandably, the thickness of the first coating layer is 5nm to 10nm, specifically 5nm, 6nm, 7nm, 8nm, 9nm or 10nm, etc., and is not limited here.

[0103] In some embodiments, the second coating layer comprises at least one of an oxide of M3 and an M3-containing lithium compound, wherein M3 comprises at least one of Al, Co, Zr, Ti, Mg, Y, La, Sr, Ba, W, Mo, Nb, and Si. The lithium compound may include at least one of LiBO2 and Li2TiO3.

[0104] In some embodiments, the high-nickel cathode material is subjected to powder XPS analysis using Al-Kα rays, and the surface of the high-nickel cathode material contains Ni. 2+ and Ni 3+ Ni 3+ The molar percentage of Ni is 30 mol% to 50 mol%, specifically 30 mol%, 32 mol%, 34 mol%, 35 mol%, 36 mol%, 38 mol%, 40 mol%, 42 mol%, 44 mol%, 46 mol%, 48 mol%, or 50 mol%, etc., and is not limited here. 2+ The molar percentage is 50 mol% to 70 mol%, specifically 50 mol%, 52 mol%, 54 mol%, 55 mol%, 56 mol%, 58 mol%, 60 mol%, 62 mol%, 64 mol%, 66 mol%, 68 mol%, or 70 mol%, etc., and is not limited here.

[0105] In some embodiments, the surface alkaline impurities of the high-nickel cathode material mainly refer to Li₂CO₃ and LiOH. The mass content of Li₂CO₃ in the high-nickel cathode material is less than 0.3 wt%. Specifically, the mass content of Li₂CO₃ in the high-nickel cathode material can be 0.05 wt%, 0.1 wt%, 0.12 wt%, and 0.2 wt%, etc., and of course, other values ​​within the above range are also possible and are not limited here. Preferably, the mass content of Li₂CO₃ in the high-nickel cathode material is less than 0.13 wt%.

[0106] In some embodiments, the mass content of LiOH in the high-nickel cathode material is less than 0.3 wt%. Specifically, the mass content of LiOH in the high-nickel cathode material can be 0.05 wt%, 0.08 wt%, 0.1 wt%, and 0.2 wt%, etc., or other values ​​within the above range, which are not limited here. Preferably, the mass content of LiOH in the high-nickel cathode material is less than 0.1 wt%.

[0107] Controlling the mass content of Li2CO3 and LiOH in high-nickel cathode materials within the above-mentioned range is beneficial to improving the processing performance of high-nickel cathode materials and reducing gas production in batteries made from high-nickel cathode materials.

[0108] In some implementations, the high-nickel cathode material has a hexagonal or monoclinic crystal structure.

[0109] The hexagonal crystal structure belongs to the order of P3, P31, P32, R3, P-3, R-3, P312, P321, P3112, P3121, P3212, P3221, R32, P3m1, P31m, P3c1, P31c, R3m, R3c, P-31m, P-31c, P-3m1, P-3c1, R-3m, R-3c, P6, P61, P65, P Any space group in the group consisting of 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.

[0110] The crystal structure of the monoclinic crystal form belongs to any 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.

[0111] Preferably, in order to obtain a secondary battery with a high discharge capacity, the high-nickel cathode material has a hexagonal crystal structure with space group R-3m or a monoclinic crystal structure with C2 / m.

[0112] In some embodiments, the powder conductivity of the high-nickel cathode material is greater than 0.02 S / cm. Specifically, the powder conductivity of the high-nickel cathode material can be 0.03 S / cm, 0.04 S / cm, 0.05 S / cm, 0.0 S / cm, and 0.07 S / cm, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0113] In some implementations, the specific surface area of ​​the high-nickel cathode material is 0.3 m². 2 / g~0.8m 2 / g, the specific surface area of ​​high-nickel cathode material can specifically be 0.3m². 2 / 、0.4m 2 / 、0.5m 2 / 、0.6m 2 / 、0.7m 2 / and 0.8m 2 / etc., of course, can also be other values ​​within the above range, and are not limited here.

[0114] In some embodiments, the particle size D50 of the high-nickel cathode material is 2.5 μm to 4.5 μm, and the average particle size of the high-nickel cathode material can be 2.5 μm, 3 μm, 3.5 μm, 4 μm, and 4.5 μm, etc. Controlling the average particle size of the high-nickel cathode material within the above range is beneficial to improving the compaction density, powder conductivity, and cycle life of the high-nickel cathode material as a cathode sheet.

[0115] This application provides a method for preparing a high-nickel cathode material, such as... Figure 1 As shown, it includes the following steps:

[0116] Step S10: The mixed solution containing the metal composite hydroxide precursor, the dopant containing the M1 element and the lithium compound is dried, and the dried product is subjected to a heat treatment to obtain the matrix material.

[0117] Step S20: The matrix material is mixed with a first coating agent containing element M2 and then subjected to a second heat treatment to obtain the first coated product; wherein, the temperature of the second heat treatment is T℃, T=700-10n. M1 / 1000, n M1 This indicates the total doping amount of element M1 in the matrix material;

[0118] Step S30: The material obtained from the first coating is mixed with a second coating agent containing element M3 and then subjected to three heat treatments to obtain a high-nickel cathode material; wherein M1, M2, and M3 are each independently selected from at least one of Al, Co, Zr, Ti, Mg, Y, La, Sr, Ba, W, Mo, Nb, and Si, and M1, M2, and M3 are all different.

[0119] In the above technical solution, the precursor, dopant, and lithium-containing compound are mixed in a mixed solution. After drying and a first heat treatment, a matrix material is obtained. This matrix material is then mixed with a first coating agent and subjected to a second heat treatment. During the second heat treatment, the temperature is controlled; the higher the M1 doping content in the matrix material, the higher the second heat treatment temperature. By rationally controlling the heat treatment temperature, the bonding strength between the coating layer and the matrix material can be effectively improved, thus enhancing the stability of the cathode material structure. The material obtained from the first coating is then mixed with a second coating agent and subjected to a third heat treatment. This ensures a tight bond between the coating layer and the matrix material of the high-nickel cathode material, reducing residual lithium on the material surface. Through multiple heat treatments, the formation of Li2Ni8O on the material surface can be suppressed. 10 Impurity phases are generated, which improves the performance of the material. At the same time, high-nickel cathode materials do not require water washing, which shortens the material preparation process and increases production capacity.

[0120] The preparation method of this application is described in detail below with reference to the embodiments:

[0121] Step S10: The mixed solution containing the metal composite hydroxide precursor, the dopant containing the M1 element and the lithium compound is dried, and the dried product is subjected to a heat treatment to obtain the matrix material.

[0122] In some embodiments, the molar ratio of metal Me to Li in the lithium-containing compound in the metal-composite hydroxide precursor is 1.0 < Li / Me < 1.1. Specifically, Li / Me can be 1.01, 1.02, 1.03, 1.05, 1.06, 1.08, and 1.09, etc., where Me represents the molar content of all metals in the metal-composite hydroxide precursor. Controlling the molar ratio of metal Me to Li in the lithium-containing compound within the above range is beneficial to the formation of matrix material grains and the improvement of material electrochemical performance. Preferably, 1.0 < Li / Me < 1.05.

[0123] In some embodiments, the general chemical formula of the metal composite hydroxide precursor is Ni. a Co b Mn c (OH)2, where 0.7 < a < 1.0, 0.0 < b < 0.05, and 0.0 < c < 0.3.

[0124] In some embodiments, the average particle size of the metal composite hydroxide precursor is 3 μm to 10 μm. The average particle size of the metal composite hydroxide precursor can be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm and 10 μm, etc., or other values ​​within the above range, which are not limited here.

[0125] In some embodiments, M1 includes at least one of Al, Co, Zr, Ti, Mg, Y, La, Sr, Ba, W, Mo, Nb, and Si.

[0126] In some implementations, the amount of M1 added is 0 to 0.3% of the total molar amount of the matrix material.

[0127] In some embodiments, the amount of M1 added is 1,000 ppm to 300,000 ppm of the total mass of the matrix material.

[0128] In some embodiments, the average particle size of the dopant containing the M1 element is 10 nm to 50 nm. Specifically, the average particle size of the dopant can be 10 nm, 20 nm, 30 nm, 40 nm and 50 nm, etc., or other values ​​within the above range, which are not limited here.

[0129] In some embodiments, the lithium-containing compound includes at least one selected from lithium carbonate, lithium hydroxide, lithium nitrate, and lithium acetate. Preferably, the lithium-containing compound includes lithium hydroxide, and specifically, lithium hydroxide includes at least one selected from anhydrous lithium hydroxide and lithium hydroxide monohydrate.

[0130] In some embodiments, the general chemical formula of the metal composite hydroxide precursor is Ni. a Co b Mn c (OH)2, where 0.7 < a < 1.0, 0.0 < b < 0.05, and 0.0 < c < 0.3.

[0131] In some embodiments, the lithium ion concentration in the mixed solution is 6 mol / L to 8 mol / L, specifically at least one selected from 6 mol / L, 6.5 mol / L, 6.8 mol / L, 6.9 mol / L, 7.2 mol / L, 7.5 mol / L, 7.8 mol / L, and 8 mol / L. Preferably, the lithium ion concentration in the mixed solution is 6 mol / L.

[0132] In some embodiments, the mixed solution also includes an oxidizing agent;

[0133] In some embodiments, the oxidant is selected from at least one of hydrogen peroxide, ozone, oxygen, air, hypochlorite, and chlorate; preferably, oxygen is used as the oxidant. Understandably, the addition of an oxidant can enhance the chemical reaction activity between the precursor and the lithium-containing compound.

[0134] In some embodiments, the amount of oxidant used is more than twice the theoretical amount of oxidant required to oxidize the metal element Me (e.g., Ni, Co, or Mn) in the metal complex hydroxide precursor to its highest valence state.

[0135] In some embodiments, the heating temperature of the mixed solution is 90°C to 100°C, specifically 90°C, 92°C, 93°C, 94°C, 95°C, 96°C, 98°C or 100°C, and is not limited here.

[0136] In some embodiments, the heating time of the mixed solution is 1 hour to 10 hours; the heating time can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours, etc., and of course, other values ​​within the above range are also possible, which are not limited here. Preferably, the heating time is 3 hours to 5 hours.

[0137] In some embodiments, the stirring speed of the mixed solution is 100 r / min to 800 r / min; specifically, the stirring speed can be 100 r / min, 200 r / min, 300 r / min, 400 r / min, 500 r / min, 600 r / min, 700 r / min, and 800 r / min, etc., or other values ​​within the above range, which are not limited here. Preferably, the stirring speed is 400 r / min to 600 r / min.

[0138] In some embodiments, the drying method is spray drying, wherein the inlet temperature of the spray dryer is 150°C to 350°C and the outlet temperature is 100°C to 150°C.

[0139] In some implementations, a single heat treatment is a multi-stage heat treatment;

[0140] In some embodiments, a heat treatment includes heating to 400-600°C at a heating rate of 1-6°C / min and holding at that temperature for 1-4 hours, followed by heating to 700-900°C at a heating rate of 1-6°C / min and holding at that temperature for 10-20 hours.

[0141] Specifically, the temperature of the first stage of the heat treatment can be 400℃, 420℃, 450℃, 470℃, 480℃, 500℃, 520℃, 550℃, 580℃, and 600℃, or other values ​​within the above range, which are not limited here. The holding time of the first stage of the heat treatment can be 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, or 4h, or other values ​​within the above range, which are not limited here. Preferably, the temperature of the first stage of the heat treatment is 500~550℃, and the holding time of the first stage is 2h~3h.

[0142] The specific temperature of the second stage of the primary heat treatment can be 700℃, 720℃, 750℃, 770℃, 780℃, 800℃, 820℃, 850℃, 880℃, and 900℃, or other values ​​within the above range, which are not limited here. The specific holding time of the second stage of the primary heat treatment can be 10h, 11.5h, 12h, 12.5h, 13h, 15h, 16h, 18h, or 20h, or other values ​​within the above range, which are not limited here. Preferably, the temperature of the second stage of the primary heat treatment is 750~850℃, and the holding time of the second stage is 10h~14h.

[0143] In some embodiments, the heating rate of a single heat treatment is 1 to 6 °C / min. Specifically, the heating rate of a single heat treatment is 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, 5.5 °C / min, and 6 °C / min, etc. Of course, other values ​​within the above range are also possible and are not limited here.

[0144] In some embodiments, the mass content of residual lithium on the surface of the matrix material is <4000ppm; specifically, it can be 2000ppm, 2200ppm, 2500ppm, 2800ppm, 3000ppm, 3200ppm, 3500ppm, 3800ppm or 3900ppm, etc., and is not limited here.

[0145] In some embodiments, the specific surface area of ​​the matrix material is 0.4 m². 2 / g~0.8m 2 / g, specifically 0.4m 2 / g, 0.5m 2 / g, 0.6m 2 / g, 0.65m 2 / g, 0.7m 2 / g, 0.75m 2 / g or 0.8m 2 / g, etc., are not limited here.

[0146] In some implementations, the equipment for primary heat treatment includes a stationary box furnace or a roller kiln-type continuous furnace.

[0147] Step S20: The matrix material is mixed with a first coating agent containing element M2 and then subjected to a second heat treatment to obtain the first coated product; wherein, the temperature of the second heat treatment is T℃, T=700-10n. M1 / 1000, n M1 This indicates the total doping amount (mass doping) of element M1 in the matrix material.

[0148] In some embodiments, the first coating agent includes at least one of an oxide of M2 and a hydroxide of M2.

[0149] In some embodiments, the amount of the first coating agent added is 10,000 ppm to 50,000 ppm of the total mass of the matrix material; specifically, it can be 10,000 ppm, 12,000 ppm, 15,000 ppm, 20,000 ppm, 25,000 ppm, 30,000 ppm, 35,000 ppm, 40,000 ppm, 45,000 ppm or 50,000 ppm, etc., and is not limited here.

[0150] In some embodiments, the temperature of the secondary heat treatment is T℃, where T = 700-10n. M1 / 1000, n M1 This indicates the total doping amount of element M1 in the matrix material. That is, the higher the doping amount of element M1 in the matrix material, the higher the temperature of the secondary heat treatment.

[0151] In some implementations, the secondary heat treatment time is 1h to 10h. Specifically, the secondary heat treatment time is 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h and 10h, etc. Of course, other values ​​within the above range are also possible and are not limited here.

[0152] In some embodiments, the heating rate of the secondary heat treatment is 1℃ / min to 6℃ / min. Specifically, the heating rate of the secondary heat treatment is 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 5.5℃ / min and 6℃ / min, etc. Of course, other values ​​within the above range are also possible and are not limited here.

[0153] In some embodiments, the secondary heat treatment is carried out in an oxygen-containing atmosphere with an oxygen concentration of ≥95%; specifically, the oxygen concentration in the oxygen-containing atmosphere can be 95%, 96%, 97%, 98%, 99%, and 99.5%, etc., or other values ​​within the above range, which are not limited here.

[0154] In some embodiments, the equipment for secondary heat treatment includes stationary box furnaces or roller kiln continuous furnaces.

[0155] In some embodiments, the mass content of residual lithium on the surface of the coating obtained by one coating is ≤1200ppm; specifically, it can be 1200ppm, 1200ppm, 1200ppm, 1200ppm, 1200ppm, 1200ppm, 1200ppm, 1200ppm, 1200ppm, 1200ppm, or 1200ppm, etc., and is not limited here.

[0156] In some embodiments, the specific surface area of ​​the material obtained from the single coating is 0.4 m². 2 / g~0.8m 2 / g, specifically 0.4m 2 / g, 0.5m 2 / g, 0.6m 2 / g, 0.65m 2 / g, 0.7m 2 / g, 0.75m 2 / g or 0.8m 2 / g, etc., are not limited here.

[0157] In some embodiments, the pH value of the product obtained from the single coating is <11.5, and may specifically be 11.3, 11.2, 11.1, 11.0, 10.8, 10.5 or 10.2, etc., which are not limited here.

[0158] Step S30: The material obtained from the first coating is mixed with a second coating agent containing element M3 and then subjected to three heat treatments to obtain a high-nickel cathode material.

[0159] In some embodiments, the second coating agent is selected from at least one oxide of M3 and a lithium-containing compound, wherein M3 is selected from at least one of Al, Co, Zr, Ti, Mg, Y, La, Sr, Ba, W, Mo, Nb, and Si. This is achieved by adding a second coating agent containing the element M3 to the product obtained from a single coating step.

[0160] In some embodiments, the temperature for the three heat treatments is between 200°C and 400°C. Specifically, the temperatures for the three heat treatments are 200°C, 250°C, 280°C, 300°C, 320°C, 360°C, 380°C, and 400°C, etc. Of course, other values ​​within the above range are also possible and are not limited here. Preferably, the temperature for the three heat treatments is between 250°C and 360°C.

[0161] In some implementations, the duration of the three heat treatments is 5h to 12h. Specifically, the duration of the three heat treatments is 5h, 6h, 7h, 8h, 9h, 10h, 11h, and 12h, etc. Of course, other values ​​within the above range are also possible and are not limited here.

[0162] In some embodiments, the heating rate of the three heat treatments is 1℃ / min to 6℃ / min. Specifically, the heating rate of the three heat treatments is 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 5.5℃ / min, and 6℃ / min, etc. Of course, other values ​​within the above range are also possible and are not limited here.

[0163] In some implementations, the equipment for the three heat treatments includes a stationary box furnace or a roller kiln-type continuous furnace.

[0164] In some implementations, the three heat treatments also include sieving and demagnetization steps.

[0165] In some implementations, the purpose of sieving is 200 mesh to 400 mesh. The specific mesh number can be 200 mesh, 210 mesh, 250 mesh, 280 mesh, 300 mesh, 350 mesh, 380 mesh and 400 mesh, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0166] This application also provides a lithium-ion battery, including a positive electrode, a negative electrode, a separator, a non-aqueous electrolyte, and a casing. The positive electrode includes a current collector and a positive electrode material coated on the current collector, such as the high-nickel positive electrode material described above or prepared by the same method as described above for preparing high-nickel positive electrode materials.

[0167] The embodiments of the present invention will be further described below with reference to several examples. However, the embodiments of the present invention are not limited to the specific embodiments described below. Appropriate modifications can be made within the scope of the original claims.

[0168] A mixed solution containing a metal composite hydroxide precursor, a dopant containing M1 element, and a lithium compound is dried, and the dried product is subjected to a single heat treatment to obtain the matrix material.

[0169] The matrix material is mixed with a first coating agent containing M2 element and then subjected to a second heat treatment to obtain the first coating product. The temperature of the second heat treatment is T℃, where T = 700-10nM1 / 1000, and nM1 represents the total doping amount of M1 element in the matrix material.

[0170] The material obtained from the first coating is mixed with a second coating agent containing element M3 and then subjected to three heat treatments to obtain a high-nickel cathode material; wherein M1, M2, and M3 are each independently composed of at least one of Al, Co, Zr, Ti, Mg, Y, La, Sr, Ba, W, Mo, Nb, and Si, and M1, M2, and M3 are all different.

[0171] Example 1

[0172] A method for preparing a high-nickel cathode material includes the following steps:

[0173] (1) Weigh a certain amount of Ni 0.885 Co 0.09 Mn 0.025 (OH)2 high-nickel single crystal precursor was added to a 6 mol / L lithium hydroxide (lithium hydroxide monohydrate) solution system. The amount of lithium hydroxide monohydrate added was based on a lithium to nickel-cobalt-manganese system molar ratio of 1.04:1. Oxygen was introduced, and the reaction was heated and stirred. Zr oxide was then uniformly added. The heating temperature was 100℃, the stirring speed was 400 rpm, and the heating reaction time was 3 h to obtain a suspension.

[0174] (2) The suspension was spray-dried using a spray dryer with an inlet temperature of 250℃ and an outlet temperature of 120℃. The suspension was rapidly spray-dried to obtain a uniformly mixed powder. The mixed powder was placed in a high-temperature sintering furnace, and an oxygen atmosphere with a concentration of over 95% was introduced at a flow rate of 60 L / min. The temperature was increased to 550℃ at a rate of 3℃ / min and held for 2 hours. Then, the temperature was increased to 830℃ at a rate of 3℃ / min and held for 10 hours. The mixture was then allowed to cool naturally to room temperature, gas-crushed, and sieved to obtain the matrix material. See [link to relevant documentation]. Figure 1 The doping amount of M1(Zr) in the matrix material is 5000ppm.

[0175] (3) The matrix material is mixed evenly with Al2O3 containing the first coating agent (the amount of Al2O3 added is 10000ppm by mass of the matrix material). Under an oxygen atmosphere with an oxygen concentration of more than 95% and an air flow rate of 60L / min, the temperature is raised to 650℃ at a heating rate of 3℃ / min in a high-temperature sintering furnace and held for 5h. The material is then naturally cooled to room temperature and sieved to obtain the material obtained from the first coating.

[0176] (4) The material obtained from the first coating is mixed evenly with the second coating agent B2O3 (the amount of B2O3 added is 1000 ppm of the mass ratio of the matrix material), and subjected to a third heat treatment at 300°C for 10 hours. After natural cooling to room temperature, the high-nickel cathode material is obtained by sieving and demagnetizing.

[0177] like Figure 2 As shown, Figure 2 This is a SEM image of the high-nickel cathode material prepared in Example 1.

[0178] The high-nickel cathode material in this embodiment includes a high-nickel matrix material Li. 1.0 Ni 0.885 Co 0.09 Mn 0.025 Zr 0.005 O 2.02 The coating layer includes a first coating layer located on the surface of the high-nickel substrate material and a second coating layer located on the first coating surface. The first coating layer includes Al2O3 and LiAlO formed by the coating reaction. 2， The second coating layer includes B2O3 and LiBO2 formed by the coating reaction.

[0179] XRD analysis was performed on the high-nickel material matrix and the high-nickel material coated product using Cu-Kα radiation. The intensity of the (104) diffraction peak appearing in the diffraction angle range of 44-45° was denoted as I. b (matrix) and I c (Coated product), diffraction peak intensity unit counts, let diffraction peak intensity difference P = I c-I b P represents the intensity difference of the (104) diffraction peaks between the matrix and the coating, and the I b (matrix), I c The intensity difference P of the (coated product) and diffraction peaks is recorded in Table 1.

[0180] High-nickel cathode materials were analyzed by Al-Kα ray powder XPS to determine the Ni content on the surface of the high-nickel cathode material. 2+ and Ni 3+ The molar percentages are recorded in Table 1, Ni 2+ molar percentage content of Ni 3+ The ratios of the molar percentage content are recorded in Table 1.

[0181] The high-nickel cathode material has a particle size D50 of 3.5 μm, a LiOH mass content of 0.25 wt%, a Li₂CO₃ mass content of 0.22 wt%, a powder conductivity of 0.025 S / cm, and a specific surface area of ​​0.6 m². 2 / g.

[0182] Example 2

[0183] Unlike Example 1, the first coating agent in step (3) is Al(OH)3.

[0184] High-nickel cathode materials include high-nickel matrix materials such as Li 1.0 Ni 0.885 Co 0.09 Mn 0.025 Zr 0.005 O 2.02 The coating layer includes a first coating layer located on the surface of the high-nickel substrate material and a second coating layer located on the first coating surface. The first coating layer includes Al2O3 and LiAlO2 formed by the coating reaction, and the second coating layer includes B2O3 and LiBO2 formed by the coating reaction.

[0185] XRD analysis was performed on the high-nickel material matrix and the high-nickel material coated product using Cu-Kα radiation. The intensity of the (104) diffraction peak appearing in the diffraction angle range of 44-45° was denoted as I. b (matrix) and I c (Coated product), diffraction peak intensity unit counts, let diffraction peak intensity difference x = I c -I b x represents the intensity difference of the (104) diffraction peak between the matrix and the coating, and the I b (matrix), I c The (coated product) and the difference in diffraction peak intensity x are recorded in Table 1.

[0186] High-nickel cathode materials were analyzed by Al-Kα ray powder XPS to determine the Ni content on the surface of the high-nickel cathode material. 2+ and Ni 3+ The molar percentages are recorded in Table 1, Ni 2+ molar percentage content of Ni 3+ The ratios of the molar percentage content are recorded in Table 1.

[0187] The high-nickel cathode material has a particle size D50 of 3.8 μm, a LiOH content of 0.29 wt%, a Li₂CO₃ content of 0.19 wt%, a powder conductivity of 0.029 S / cm, and a specific surface area of ​​0.65 m². 2 / g.

[0188] Example 3

[0189] Unlike Example 1, in step (3), the first coating agent is Zr(OH)4, and the amount of Zr(OH)4 added is 10,000 ppm by mass of the matrix material;

[0190] High-nickel cathode materials include high-nickel matrix materials such as Li 1.0 Ni 0.885 Co 0.09 Mn 0.025 Zr 0.005 O 2.02 The coating layer includes a first coating layer located on the surface of the high-nickel substrate material and a second coating layer located on the first coating surface. The first coating layer includes ZrO2 and Li2ZrO3 formed by the coating reaction, and the second coating layer includes B2O3 and LiBO2 formed by the coating reaction.

[0191] XRD analysis was performed on the high-nickel material matrix and the high-nickel material coated product using Cu-Kα radiation. The intensity of the (104) diffraction peak appearing in the diffraction angle range of 44-45° was denoted as I. b (matrix) and I c (Coated product), diffraction peak intensity unit counts, let diffraction peak intensity difference x = I c -I b x represents the intensity difference of the (104) diffraction peak between the matrix and the coating, and the I b (matrix), I c The (coated product) and the difference in diffraction peak intensity x are recorded in Table 1.

[0192] High-nickel cathode materials were analyzed by Al-Kα ray powder XPS to determine the Ni content on the surface of the high-nickel cathode material. 2+ and Ni 3+ The molar percentages are recorded in Table 1, Ni2+ molar percentage content of Ni 3+ The ratios of the molar percentage content are recorded in Table 1.

[0193] The high-nickel cathode material has a particle size D50 of 3.0 μm, a LiOH mass content of 0.18 wt%, a Li₂CO₃ mass content of 0.25 wt%, a powder conductivity of 0.035 S / cm, and a specific surface area of ​​0.75 m². 2 / g.

[0194] Example 4

[0195] Unlike Example 1, the second heat treatment temperature in step (3) is 600°C and the total matrix doping amount is 10,000 ppm.

[0196] The high-nickel cathode material includes a high-nickel matrix material Li. 1.0 Ni 0.885 Co 0.09 Mn 0.025 Zr 0.01 O 2.04 The coating layer includes a first coating layer located on the surface of the high-nickel substrate material and a second coating layer located on the first coating surface. The first coating layer includes Al2O3 and LiAlO2 formed by the coating reaction, and the second coating layer includes B2O3 and LiBO2 formed by the coating reaction.

[0197] XRD analysis was performed on the high-nickel material matrix and the high-nickel material coated product using Cu-Kα radiation. The intensity of the (104) diffraction peak appearing in the diffraction angle range of 44-45° was denoted as I. b (matrix) and I c (Coated product), diffraction peak intensity unit counts, let diffraction peak intensity difference P = I c -I b P represents the intensity difference of the (104) diffraction peaks between the matrix and the coating, and the I b (matrix), I c The intensity difference P of the (coated product) and diffraction peaks is recorded in Table 1.

[0198] High-nickel cathode materials were analyzed by Al-Kα ray powder XPS to determine the Ni content on the surface of the high-nickel cathode material. 2+ and Ni 3+ The molar percentages are recorded in Table 1, Ni 2+ molar percentage content of Ni 3+ The ratios of the molar percentage content are recorded in Table 1.

[0199] The high-nickel cathode material has a particle size D50 of 3.3 μm, a LiOH mass content of 0.22 wt%, a Li₂CO₃ mass content of 0.28 wt%, a powder conductivity of 0.030 S / cm, and a specific surface area of ​​0.70 m². 2 / g.

[0200] Example 5

[0201] Unlike Example 1, the heat treatment time for the second heat treatment in step (3) is 8 hours.

[0202] The high-nickel cathode material includes a high-nickel matrix material Li. 1.0 Ni 0.885 Co 0.09 Mn 0.025 Zr 0.005 O 2.02 The coating layer includes a first coating layer located on the surface of the high-nickel substrate material and a second coating layer located on the first coating surface. The first coating layer includes Al2O3 and LiAlO2 formed by the coating reaction, and the second coating layer includes B2O3 and LiBO2 formed by the coating reaction.

[0203] XRD analysis was performed on the high-nickel material matrix and the high-nickel material coated product using Cu-Kα radiation. The intensity of the (104) diffraction peak appearing in the diffraction angle range of 44-45° was denoted as I. b (matrix) and I c (Coated product), diffraction peak intensity unit counts, let diffraction peak intensity difference P = I c -I b P represents the intensity difference of the (104) diffraction peaks between the matrix and the coating, and the I b (matrix), I c The intensity difference P of the (coated product) and diffraction peaks is recorded in Table 1.

[0204] The high-nickel cathode material was analyzed by Al-Kα ray powder XPS, and the Ni content on the surface of the high-nickel cathode material was determined. 2+ and Ni 3+ The molar percentages are recorded in Table 1, Ni 2+ molar percentage content of Ni 3+ The ratios of the molar percentage content are recorded in Table 1.

[0205] The high-nickel cathode material has a particle size D50 of 3.6 μm, a LiOH mass content of 0.25 wt%, a Li₂CO₃ mass content of 0.28 wt%, a powder conductivity of 0.030 S / cm, and a specific surface area of ​​0.68 m².2 / g.

[0206] Example 6

[0207] Unlike Example 1, the third heat treatment temperature in step (4) is 500°C. The high-nickel cathode material includes a high-nickel matrix material Li. 1.0 Ni 0.885 Co 0.09 Mn 0.025 Zr 0.005 O 2.02 The coating layer includes a first coating layer located on the surface of the high-nickel substrate material and a second coating layer located on the first coating surface. The first coating layer includes Al2O3 and LiAlO2 formed by the coating reaction, and the second coating layer includes B2O3 and LiBO2 formed by the coating reaction.

[0208] XRD measurements were performed on the high-nickel material matrix and the high-nickel material coated product using Cu-Kα rays. The intensity of the (104) diffraction peak appearing in the diffraction angle range of 44-45° was denoted as I. b (matrix) and I c (Coated product), diffraction peak intensity unit counts, let diffraction peak intensity difference P = I c -I b P represents the intensity difference of the (104) diffraction peaks between the matrix and the coating, and the I b (matrix), I c The intensity difference P of the (coated product) and diffraction peaks is recorded in Table 1.

[0209] High-nickel cathode materials were analyzed by Al-Kα ray powder XPS to determine the Ni content on the surface of the high-nickel cathode material. 2+ and Ni 3+ The molar percentages are recorded in Table 1, Ni 2+ molar percentage content of Ni 3+ The ratios of the molar percentage content are recorded in Table 1.

[0210] The high-nickel cathode material has a particle size D50 of 3.9 μm, a LiOH mass content of 0.24 wt%, a Li₂CO₃ mass content of 0.29 wt%, a powder conductivity of 0.031 S / cm, and a specific surface area of ​​0.78 m². 2 / g.

[0211] Example 7

[0212] Unlike Example 1, the second heat treatment temperature in step (3) is 650°C, and 5000ppm Zr is doped.

[0213] High-nickel cathode materials include high-nickel matrix materials such as Li 1.0 Ni 0.885 Co 0.09 Mn 0.025 Zr 0.005 O 2.02 The coating layer includes a first coating layer located on the surface of the high-nickel substrate material and a second coating layer located on the first coating surface. The first coating layer includes Al2O3 and LiAlO2 formed by the coating reaction, and the second coating layer includes B2O3 and LiBO2 formed by the coating reaction.

[0214] XRD analysis was performed on the high-nickel material matrix and the high-nickel material coated product using Cu-Kα radiation. The intensity of the (104) diffraction peak appearing in the diffraction angle range of 44-45° was denoted as I. b (matrix) and I c (Coated product), diffraction peak intensity unit counts, let diffraction peak intensity difference P = I c -I b P represents the intensity difference of the (104) diffraction peaks between the matrix and the coating, and the I b (matrix), I c The (coated product) and the difference in diffraction peak intensity x are recorded in Table 1.

[0215] High-nickel cathode materials were analyzed by Al-Kα ray powder XPS to determine the Ni content on the surface of the high-nickel cathode material. 2+ and Ni 3+ The molar percentages are recorded in Table 1, Ni 2+ molar percentage content of Ni 3+ The ratios of the molar percentage content are recorded in Table 1.

[0216] The high-nickel cathode material has a particle size D50 of 3.0 μm, a LiOH mass content of 0.18 wt%, a Li₂CO₃ mass content of 0.25 wt%, a powder conductivity of 0.035 S / cm, and a specific surface area of ​​0.75 m². 2 / g.

[0217] Example 8

[0218] Unlike Example 1, the first coating agent in step (3) is Ti(OH)4. The amount of Ti added is 15000 ppm by mass of the matrix material.

[0219] The high-nickel cathode material includes a high-nickel matrix material Li. 1.0 Ni 0.885 Co 0.09 Mn 0.025 Zr 0.005 O2.02 The coating layer includes a first coating layer located on the surface of the high-nickel substrate material and a second coating layer located on the first coating surface. The first coating layer includes TiO2 and Li2TiO3 formed by the coating reaction, and the second coating layer includes B2O3 and LiBO2 formed by the coating reaction.

[0220] XRD measurements were performed on the high-nickel material matrix and the high-nickel material coated product using Cu-Kα rays. The intensity of the (104) diffraction peak appearing in the diffraction angle range of 44-45° was denoted as I. b (matrix) and I c (Coated product), diffraction peak intensity unit counts, let diffraction peak intensity difference x = I c -I b x represents the intensity difference of the (104) diffraction peak between the matrix and the coating, and I b (matrix), I c The (coated product) and the difference in diffraction peak intensity x are recorded in Table 1.

[0221] High-nickel cathode materials were analyzed by Al-Kα ray powder XPS to determine the Ni content on the surface of the high-nickel cathode material. 2+ and Ni 3+ The molar percentages are recorded in Table 1, Ni 2+ molar percentage content of Ni 3+ The ratios of the molar percentage content are recorded in Table 1.

[0222] The high-nickel cathode material has a particle size D50 of 3.6 μm, a LiOH mass content of 0.20 wt%, a Li₂CO₃ mass content of 0.29 wt%, a powder conductivity of 0.028 S / cm, and a specific surface area of ​​0.59 m². 2 / g.

[0223] Comparative Example 1

[0224] Unlike Example 1, in step (4), the material obtained from the first coating and the second coating agent (B2O3) containing M3 are mixed evenly, subjected to a third heat treatment at 300°C and kept at that temperature for 10 hours, and then naturally cooled to room temperature. After sieving and demagnetizing, a high-nickel cathode material is obtained.

[0225] XRD analysis was performed on the high-nickel material matrix and the high-nickel material coated product using Cu-Kα radiation. The intensity of the (104) diffraction peak appearing in the diffraction angle range of 44-45° was denoted as I. b (matrix) and I c (Coated product), diffraction peak intensity unit counts, let diffraction peak intensity difference x = I c -Ib x represents the intensity difference of the (104) diffraction peak between the matrix and the coating, and the I b (matrix), I c The (coated product) and the difference in diffraction peak intensity x are recorded in Table 1.

[0226] High-nickel cathode materials were analyzed by Al-Kα ray powder XPS to determine the Ni content on the surface of the high-nickel cathode material. 2+ and Ni 3+ The molar percentages are recorded in Table 1, Ni 2+ molar percentage content of Ni 3+ The ratios of the molar percentage content are recorded in Table 1.

[0227] The high-nickel cathode material has a particle size D50 of 2.8 μm, a LiOH mass content of 0.21 wt%, a Li₂CO₃ mass content of 0.27 wt%, a powder conductivity of 0.031 S / cm, and a specific surface area of ​​0.76 m². 2 / g.

[0228] Comparative Example 2

[0229] Unlike Example 1, in step (4), the material obtained from the first coating and the second coating agent (Al2O3) containing M3 are mixed evenly, subjected to a third heat treatment at 750°C and kept at that temperature for 10 hours, and then naturally cooled to room temperature. After sieving and demagnetization, a high-nickel cathode material is obtained.

[0230] XRD measurements were performed on the high-nickel material matrix and the high-nickel material coated product using Cu-Kα rays. The intensity of the (104) diffraction peak appearing in the diffraction angle range of 44-45° was denoted as I. b (matrix) and I c (Coated product), diffraction peak intensity unit counts, let diffraction peak intensity difference P = I c -I b P represents the intensity difference of the (104) diffraction peaks between the matrix and the coating, and the I b (matrix), I c The intensity difference P of the (coated product) and diffraction peaks is recorded in Table 1.

[0231] High-nickel cathode materials were analyzed by Al-Kα ray powder XPS to determine the Ni content on the surface of the high-nickel cathode material. 2+ and Ni 3+ The molar percentages are recorded in Table 1, Ni 2+ molar percentage content of Ni 3+ The ratios of the molar percentage content are recorded in Table 1.

[0232] The high-nickel cathode material has a particle size D50 of 3.0 μm, a LiOH mass content of 0.15 wt%, a Li₂CO₃ mass content of 0.35 wt%, a powder conductivity of 0.019 S / cm, and a specific surface area of ​​0.70 m². 2 / g.

[0233] Comparative Example 3

[0234] Unlike Example 1, in step (4), the material obtained from the first coating and the second coating agent (B2O3) containing M3 are mixed evenly, subjected to a third heat treatment at 300°C and kept at that temperature for 5 hours, and then naturally cooled to room temperature. After sieving and demagnetizing, a high-nickel cathode material is obtained.

[0235] XRD measurements were performed on the high-nickel material matrix and the high-nickel material coated product using Cu-Kα rays. The intensity of the (104) diffraction peak appearing in the diffraction angle range of 44-45° was denoted as I. b (matrix) and I c (Coated product), diffraction peak intensity unit counts, let diffraction peak intensity difference x = I c -I b x represents the intensity difference of the (104) diffraction peak between the matrix and the coating, and the I b (matrix), I c The (coated product) and the difference in diffraction peak intensity x are recorded in Table 1.

[0236] High-nickel cathode materials were analyzed by Al-Kα ray powder XPS to determine the Ni content on the surface of the high-nickel cathode material. 2+ and Ni 3+ The molar percentages are recorded in Table 1, Ni 2+ molar percentage content of Ni 3+ The ratios of the molar percentage content are recorded in Table 1.

[0237] The high-nickel cathode material has a particle size D50 of 4.0 μm, a LiOH mass content of 0.31 wt%, a Li₂CO₃ mass content of 0.25 wt%, a powder conductivity of 0.018 S / cm, and a specific surface area of ​​0.89 m². 2 / g.

[0238] Performance testing:

[0239] (1) Alkaline impurity test of high-nickel materials:

[0240] The content of alkaline impurities on the surface of high-nickel materials is a characteristic of the material surface, which can be quantitatively measured by analyzing the reaction products between the surface and water. When high-nickel material powder is immersed in water, a surface reaction occurs. During the reaction, the pH of the water increases (as the alkaline impurities dissolve), and the alkaline content is quantified by pH titration. The titration result is the alkaline impurity content. The alkaline impurity content can be measured as follows: 5.0 g of high-nickel material powder is immersed in 100 ml of deionized water and stirred for 10 minutes in a sealed glass flask. After stirring to dissolve the alkali, the suspension of powder in water is filtered to obtain a clear solution. Then, 90 ml of the clear solution is titrated with 0.1 M HCl at a rate of 0.5 ml / min while stirring, by recording the pH curve until the pH reaches 3. A reference voltage curve is obtained by titrating a suitable mixture of LiOH and Li₂CO₃ dissolved in deionized water at low concentrations. In almost all cases, two distinct plateaus are observed. The upper plateau with an endpoint y₁ (in ml) between pH 8 and 9 is the equilibrium OH group. - / H2O, followed by balancing CO3. 2- / HCO3 - The lower plateau with an endpoint y2 (in ml) between pH 4 and 6 is HCO3. - / H2CO3. The inflection point y1 between the first and second plateaus and the inflection point y2 after the second plateau are obtained by the corresponding minimum values ​​of the derivative dpH / dVol of the pH curve. The second inflection point is generally close to pH 4.7. The results are then expressed as weight percentages of LiOH and Li2CO3 as shown in equations (3) and (4):

[0241]

[0242]

[0243] (2) XPS testing of high-nickel cathode materials:

[0244] X-ray photoelectron spectroscopy (XPS) can analyze materials from the surface down to a depth range of approximately 5 nm to 10 nm (typically around 5 nm), allowing for quantitative analysis of elemental concentrations in about half of the surface layer. Furthermore, narrow-scan analysis allows for analysis of elemental bonding states. X-ray photoelectron spectroscopy (XPS) can be performed using, for example, the ULVAC-PHI X-ray photoelectron spectroscopy analyzer (Quantera II). X-ray source: Al monochromatic 100 μm, 25 W, 15 kV; no surface etching; photoelectron extraction angle: 45°; bonding energy correction: the C1s peak was set to 284.6 eV; XPS was performed on the high-nickel material of this invention. Based on the obtained XPS spectrum, the Ni2P peak appearing at a binding energy of 850 eV to 870 eV was identified. 3 / 2 Peak separation and curve fitting were performed to determine Ni. 2+ Peak area and Ni 3+ Peak area.

[0245] (3) XRD testing of high-nickel cathode materials:

[0246] When performing XRD tests on the material, Cu-Kα rays were used as the X-ray source, and the test conditions were 10-90° (2θ) with a scanning step size of 0.05°. The measured XRD data of the positive electrode active material were exported, and the experimental data and theoretical data were fitted multiple times using the least squares method in Fullpro software until the error factor was within a sufficiently small range to obtain refined data. The intensity of the (104) diffraction peaks appearing in the diffraction angle range of 44-45° was recorded as I. b (matrix) and I c (Covered products).

[0247] (4) Battery capacity calibration

[0248] First, the battery capacity was calibrated by charging it to 4.25V at 1 / 3C current at room temperature (25℃), letting it stand for 30 minutes, then discharging it to 2.5V at 1 / 3C current, letting it stand for 30 minutes, repeating the cycle twice, and setting the second discharge capacity as C0. This was then used as a benchmark for subsequent DCIR testing.

[0249] (5) DCIR test (protection voltage 1.0V~4.4V, test temperature: 25℃)

[0250] a. Charge at 0.2C0 constant current to 10%C0 at 25℃, let stand for 2 hours [termination voltage recorded as V1], test DCIR (discharge at 1.5C0 for 30 seconds [termination voltage recorded as V2], let stand for 30 minutes [termination voltage recorded as V3]; charge at 1.5C0 for 30 seconds [termination voltage recorded as V4], let stand for 5 minutes), discharge at 0.33C0 to 2.5V / cell, let stand for 30 minutes;

[0251] b. Charge at 25℃ with a constant current of 0.2C0 to 20%C0, let stand for 2 hours [the termination voltage is recorded as V1], test DCIR (discharge at 1.5C0 for 30 seconds [the termination voltage is recorded as V2], let stand for 30 minutes [the termination voltage is recorded as V3]; charge at 1.5C0 for 30 seconds [the termination voltage is recorded as V4], let stand for 5 minutes), discharge at 0.33C0 to 2.5V / cell, let stand for 30 minutes;

[0252] c. Charge at 0.2C0 constant current to 50%C0 at 25℃, let stand for 2 hours [termination voltage recorded as V1], test DCIR (discharge at 1.5C0 for 30 seconds [termination voltage recorded as V2], let stand for 30 minutes [termination voltage recorded as V3]; charge at 1.5C0 for 30 seconds [termination voltage recorded as V4], let stand for 5 minutes), discharge at 0.33C0 to 2.5V / cell, let stand for 30 minutes;

[0253] d. Charge at 0.2C0 constant current to 80%C0 at 25℃, let stand for 2 hours [termination voltage recorded as V1], test DCIR (discharge at 1.5C0 for 30 seconds [termination voltage recorded as V2], let stand for 30 minutes [termination voltage recorded as V3]; charge at 1.5C0 for 30 seconds [termination voltage recorded as V4], let stand for 5 minutes), discharge at 0.33C0 to 2.5V / cell, let stand for 30 minutes;

[0254] Calculate the DCIR values ​​for different SOCs using the following formulas (5) and (6):

[0255] DCIR release = (V1-V2) / 1.5C0*1000 (unit: mΩ) (5)

[0256] DCIR charge = (V1-V2) / 1.5C0*1000 (unit: mΩ) (6)

[0257] The DCIR value was measured after every 100 cycles using the same method as the DCIR measurement before the cycle described above.

[0258] (6) Thickness expansion test of full cells made of high-nickel materials:

[0259] At room temperature, the battery was charged at a constant current of 0.5C to 4.25V, and then charged at a constant voltage to a current of 0.05C. At this point, the battery was in a fully charged state. The initial thickness of the fully charged battery before storage was measured, and then the battery was placed in a 60℃ oven. The thickness of the battery was measured every 20 days, and the battery thickness expansion rate was calculated according to the following formula (7):

[0260] Thickness expansion rate = (thickness after storage - thickness before storage) / (thickness before storage) (7)

[0261] Table 1. Statistical table of XPS and XDR test results of high-nickel cathode materials prepared in each embodiment and comparative example.

[0262]

[0263] Table 2 shows a comparison of the performance tests of the high-nickel cathode materials in Examples 1-8 and Comparative Examples 1-3 of this application.

[0264] Table 2. Performance tests of high-nickel cathode materials from Examples 1-8 and Comparative Examples 1-3

[0265]

[0266]

[0267] According to the high-nickel cathode materials prepared in Examples 1-8 and Comparative Examples 1-3 of this application, the capacity retention rate of full cells at 45°C for 300 cycles at 1C / 1C under different voltages was tested. High-temperature performance tests showed that the high-temperature cycling performance of the cathode materials in the examples and comparative examples changed significantly. Under conditions of 2.5V to 4.2V, the capacity retention rate of the cathode materials in some examples of this application was around 94%, while the capacity retention rate of the cathode materials in the comparative examples was below 92%. Tests under conditions of 2.5V to 4.25V showed that due to phase transitions, the high-temperature cycling performance of the samples in both examples and comparative examples decreased. However, some examples still showed significantly better performance than the comparative examples.

[0268] Full cells were fabricated using the high-nickel cathode materials prepared according to the embodiments and comparative examples of this application. The DC internal resistance growth of the full cells was tested at 2.5-4.25V and 45°C for 100, 200, and 300 cycles per 1C / 1C. The DC internal resistance growth of the embodiments was significantly lower than that of the comparative examples. This indicates that the samples from the embodiments have better structural stability, with more stable surface and internal structures.

[0269] Full cells were fabricated using high-nickel cathode materials prepared according to the embodiments and comparative examples of this application. Then, their gas production during storage at a high temperature of 60°C was tested. The cell thickness was measured every 20 days, and the thickness expansion rate was calculated. As shown in Table 1, the cell thickness growth of the embodiments and comparative examples changed significantly. However, the thickness expansion growth of the embodiments was significantly lower than that of the comparative examples.

[0270] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A high-nickel cathode material, characterized in that, The general chemical formula of the high-nickel cathode material is: , where 0.80 < <1.20, a+b+c+x+y+z=1, 0.7<a<1.0, 0<b<0.05, 0<c<0.3, 0<x<0.3, 0<y<0.3, 0<z<0.3, 0<α<0.1, M1, M2, and M3 are each independently composed of at least one of Al, Co, Zr, Ti, Mg, Y, La, Sr, Ba, W, Mo, Nb, and Si, and M1, M2, and M3 are all different; the high-nickel cathode material includes a high-nickel material matrix and a coating layer at least partially located on the high-nickel material matrix, the coating layer includes a first coating layer and a second coating layer, the first coating layer includes an oxide of M2 and a lithium compound containing M2, and the second coating layer includes an oxide of M3 and a lithium compound containing M3; Powder XPS analysis was performed on the surface region of the high-nickel cathode material using Al-Kα radiation, revealing that the surface region of the high-nickel cathode material contains Ni. 2+ and Ni 3+ Ni 2+ molar content of Ni 3+ The ratio of the molar content of the components is set as Q, where 0.5 < Q < 3.

2. The high-nickel cathode material according to claim 1, characterized in that, The material includes at least one of the following features (1) to (4): (1) The general chemical formula of the high-nickel material matrix is: 0.80 < <1.20, 0.7<a<1.0, 0<b<0.05, 0<c<0.3, 0<x<0.3, 0<α<0.1; (2) A first coating layer is formed on the surface of the high-nickel material substrate, and a second coating layer is formed on the surface of the first coating layer; (3) The thickness of the first coating layer is 5nm~50nm; (4) The thickness of the second coating layer is 5nm~50nm.

3. The high-nickel cathode material according to claim 1, characterized in that, The high-nickel cathode material includes at least one of the following features (1) to (10): (1) The high-nickel cathode material includes secondary particles, and the secondary particles include multiple primary particles; (2) The surface region of the high-nickel cathode material refers to the region from the high-nickel surface to the center, which is 5nm to 10nm. (3) The high-nickel cathode material was subjected to powder XPS analysis using Al-Kα radiation. The surface of the high-nickel cathode material contained Ni. 2+ Ni 2+ The molar content is 50 mol%~70 mol%; (4) The high-nickel cathode material was subjected to powder XPS analysis using Al-Kα radiation, and the surface of the high-nickel cathode material contained Ni. 3+ Ni 3+ The molar content is 30 mol%~50 mol%; (5) The mass content of LiOH in the high-nickel cathode material is less than 0.3 wt%; (6) The mass content of Li2CO3 in the high-nickel cathode material is less than 0.3 wt%; (7) The crystal structure of the high-nickel cathode material belongs to the hexagonal crystal structure or the monoclinic crystal structure; (8) The powder conductivity of the high-nickel cathode material is greater than 0.02 S / cm; (9) The specific surface area of ​​the high-nickel cathode material is 0.3 m². 2 / g ~0.8m 2 / g; (10) The particle size D50 of the high-nickel cathode material is 2.5μm~4.5μm.

4. A method for preparing the high-nickel cathode material according to any one of claims 1 to 3, characterized in that, Includes the following steps: A mixed solution containing a metal composite hydroxide precursor, a dopant containing M1 element, and a lithium compound is dried, and the dried product is subjected to a single heat treatment to obtain the matrix material. The matrix material is mixed with a first coating agent containing M2 element and then subjected to a second heat treatment to obtain the first coated product. The temperature of the second heat treatment is T℃, where T = 700-10n. M1 / 1000, n M1 This indicates the total mass doping amount of element M1 in the matrix material; The material obtained from the first coating is mixed with a second coating agent containing element M3 and then subjected to three heat treatments to obtain a high-nickel cathode material; wherein M1, M2, and M3 are each independently composed of at least one of Al, Co, Zr, Ti, Mg, Y, La, Sr, Ba, W, Mo, Nb, and Si, and M1, M2, and M3 are all different.

5. The preparation method according to claim 4, characterized in that, The method includes at least one of the following features (1) to (19): (1) The molar ratio of the metal composite hydroxide precursor, the dopant containing M1 element, and the lithium-containing compound is 1:(0~0.3):(1.0~1.2). (2) The molar ratio of the total metal Me in the metal composite hydroxide precursor to Li in the lithium-containing compound is 1.0 < Li / Me < 1.1; (3) The lithium-containing compound includes lithium hydroxide; (4) The lithium-containing compound is lithium hydroxide, and the lithium hydroxide includes at least one of anhydrous lithium hydroxide and lithium hydroxide monohydrate; (5) The mixed solution includes a solvent, wherein the solvent is deionized water; (6) The general chemical formula of the metal composite hydroxide precursor is Ni a Co b Mn c (OH)2, where 0.7 < a < 1.0, 0.0 < b < 0.05, 0.0 < c < 0.3; (7) The concentration of lithium-containing compounds in the mixed solution is 6 mol / L to 8 mol / L; (8) The mixed solution also includes an oxidizing agent; (9) The mixed solution further includes an oxidizing agent, which includes at least one of hydrogen peroxide, ozone, oxygen, air, hypochlorite and chlorate; (10) The amount of M1 element added is 0~0.3% of the total molar amount of the matrix material; (11) The heating temperature of the mixed solution is 90℃~100℃; (12) The heating time of the mixed solution is 1h to 10h; (13) The stirring speed of the mixed solution is 100 r / min to 800 r / min; (14) The drying method is spray drying, and the inlet temperature of the spray dryer is 150℃~350℃ and the outlet temperature is 100℃~150℃; (15) The primary heat treatment is a staged heat treatment; (16) The first heat treatment includes heating to 400-600℃ at a heating rate of 1-6℃ / min and holding for 1-4h, and then heating to 700-900℃ at a heating rate of 1-6℃ / min and holding for 10-20h. (17) The first heat treatment includes heating to 500-550°C at a heating rate of 1-6°C / min and holding for 2-3 hours, and then heating to 750-850°C at a heating rate of 1-6°C / min and holding for 10-14 hours. (18) The mass content of residual lithium on the surface of the matrix material is <4000 ppm; (19) The specific surface area of ​​the matrix material is 0.4 m². 2 / g~1.0m 2 / g.

6. The preparation method according to claim 4, characterized in that, The method includes at least one of the following features (1) to (8): (1) The first coating agent includes at least one of the oxide of M2 and the hydroxide of M2; (2) The amount of the first coating agent added is 10,000 ppm to 50,000 ppm by mass of the matrix material; (3) The duration of the secondary heat treatment is 1 hour to 10 hours; (4) The heating rate of the secondary heat treatment is 1℃ / min to 6℃ / min; (5) The secondary heat treatment is carried out in an oxygen-containing atmosphere, wherein the oxygen concentration in the oxygen-containing atmosphere is ≥90%; (6) The mass content of residual lithium on the surface of the material obtained by the first coating is ≤1500ppm; (7) The specific surface area of ​​the material obtained by the first coating is 0.4 m². 2 / g~0.8m 2 / g; (8) The pH value of the product obtained by the first coating is <11.

5.

7. The preparation method according to claim 4, characterized in that, The method includes at least one of the following features (1) to (6): (1) The second coating agent is selected from at least one of the oxides of M3 and lithium-containing compounds; (2) The amount of the second coating agent added is 10,000 ppm to 50,000 ppm by mass of the matrix material; (3) The temperature of the three heat treatments is 200℃~400℃; (4) The duration of the three heat treatments is 5h~12h; (5) The heating rate of the three heat treatments is 1℃ / min to 6℃ / min; (6) The three heat treatments are carried out in an oxygen-containing atmosphere, wherein the oxygen concentration in the oxygen-containing atmosphere is greater than or equal to 90%.

8. The preparation method according to any one of claims 4 to 7, characterized in that, The method includes at least one of the following features (1) to (9): (1) The matrix material and the high-nickel cathode material were XRD measured by Cu-Kα rays. The intensity of the (104) diffraction peaks appearing in the diffraction angle range of 44-45° were denoted as Ib (matrix material) and Ic (high-nickel cathode material), respectively. The unit of diffraction peak intensity was counts. Let the diffraction peak intensity difference P = Ic-Ib, 0 < P < 1000; (2) The high-nickel cathode material was subjected to powder XPS analysis using Al-Kα rays, and the surface of the high-nickel cathode material contained Ni. 2+ Ni 2+ The molar content is 50 mol%~70 mol%; (3) The high-nickel cathode material was subjected to powder XPS analysis using Al-Kα radiation. The surface of the high-nickel cathode material contained Ni. 3+ Ni 3+ The molar content is 30 mol%~50 mol%; (4) The mass content of LiOH in the high-nickel cathode material is less than 0.3 wt%; (5) The mass content of Li2CO3 in the high-nickel cathode material is less than 0.3 wt%; (6) The crystal structure of the high-nickel cathode material belongs to the hexagonal crystal structure or the monoclinic crystal structure; (7) The powder conductivity of the high-nickel cathode material is greater than 0.02 S / cm; (8) The specific surface area of ​​the high-nickel cathode material is 0.3 m². 2 / g ~0.8m 2 / g; (9) The particle size D50 of the high-nickel cathode material is 2.5μm~4.5μm.

9. A lithium-ion battery, characterized in that, The lithium-ion battery comprises the high-nickel cathode material according to any one of claims 1 to 3 or the high-nickel cathode material prepared by the method according to any one of claims 4 to 8.

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