Positive electrode active material and preparation method therefor, positive electrode sheet, battery, and electrical device

Abstract

A positive electrode active material and a preparation method therefor, a positive electrode sheet, a battery, and an electrical device, relating to the technical field of batteries. In an XRD pattern of the positive electrode active material, a characteristic peak C(018) corresponding to a (018) crystal plane of the positive electrode active material exhibits a bimodal distribution, comprising a first characteristic peak C1(018) and a second characteristic peak C2(018); and a characteristic peak D(110) corresponding to a (110) crystal plane of the positive electrode active material exhibits a bimodal distribution, comprising a first characteristic peak D1(110) and a second characteristic peak D2(110). IC1 denotes the intensity of the first characteristic peak C1(018), ID1 denotes the intensity of the first characteristic peak D1(110), and 0.80 ≤ ID1 / IC1 ≤ 1.00. Thus, the first charge-discharge efficiency, discharge capacity, cycling performance, and safety performance of a battery comprising the positive electrode active material can be effectively improved, and the impedance of the battery can be reduced.

Description

Positive electrode active materials and their preparation methods, positive electrode sheets, batteries and electrical devices

[0001] Priority information

[0002] This disclosure claims priority and benefits to patent application No. 202411218275.2, filed with the China National Intellectual Property Administration on August 30, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure pertains to the field of batteries, specifically relating to a positive electrode active material and its preparation method, a positive electrode sheet, a battery, and electrical equipment. Background Technology

[0004] Lithium-ion batteries have become the primary power source for portable electronic devices, electric vehicles, and energy storage systems due to their high energy density, long cycle life, and environmental friendliness. Currently, the most widely used cathode materials for lithium-ion batteries include lithium cobalt oxide, nickel-cobalt-manganese ternary layered materials, lithium iron phosphate, lithium manganese iron phosphate, and lithium manganese oxide spinel cathode materials. Among these, nickel-cobalt-manganese ternary layered materials are considered ideal for lithium-ion battery cathode materials due to their high theoretical specific capacity (approximately 274 mAh / g). However, cobalt is scarce, expensive, and causes environmental pollution; therefore, the research and application of low-cobalt or even cobalt-free cathode materials have received widespread attention.

[0005] In nickel-cobalt-manganese ternary layered materials, the reduction in the proportion of cobalt leads to problems such as decreased initial charge-discharge efficiency, poor rate performance, deterioration of cycle performance, and increased impedance, which seriously restricts the promotion and application of low-cobalt and cobalt-free layered cathode materials.

[0006] Summary of the Invention

[0007] This disclosure aims to at least partially address one of the technical problems in the related art. To this end, one object of this disclosure is to provide a positive electrode active material and its preparation method, a positive electrode sheet, a battery, and an electrical device, to solve the problems of decreased initial charge / discharge efficiency, deteriorated rate performance, worsened cycle performance, and increased impedance caused by the reduction in the proportion of cobalt.

[0008] In one aspect of this disclosure, a positive electrode active material is provided. According to an embodiment of this disclosure, the positive electrode active material comprises:

[0009] In the XRD pattern of the positive electrode active material, the characteristic peak C(018) corresponding to the (018) crystal plane of the positive electrode active material exhibits a bimodal distribution, including a first characteristic peak C located on the small-angle side. 1 (018) and the second characteristic peak C on the large angle side2 (018);

[0010] The characteristic peak D(110) corresponding to the (110) crystal plane of the positive electrode active material exhibits a bimodal distribution, including the first characteristic peak D located on the small angle side. 1 (110) and the second characteristic peak D on the large angle side 2 (110);

[0011] I C1 The first characteristic peak C corresponding to the (018) crystal plane of the positive electrode active material is indicated by... 1 The strength of (018), I D1 The first characteristic peak D corresponding to the (110) crystal plane of the positive electrode active material is represented by... 1 The strength of (110) satisfies 0.80 ≤ I D1 / I C1 ≤1.00.

[0012] The positive electrode active material according to the embodiments of this disclosure effectively improves the structural stability and interface stability of the positive electrode active material, and also effectively reduces the Li / Ni mixing degree of the positive electrode material, thereby effectively improving the cycle performance, first charge and discharge efficiency, discharge capacity and safety performance of the battery, and also effectively reducing the initial impedance and impedance increase of the battery.

[0013] In addition, the positive electrode active material according to the above embodiments of this disclosure may also have the following additional technical features:

[0014] In some embodiments of this disclosure, I C1 and I D1 Satisfying 0.85≤I D1 / I C1 ≤0.95.

[0015] In some embodiments of this disclosure, A C1 The first characteristic peak C corresponding to the (018) crystal plane of the positive electrode active material is indicated by... 1 (018) peak area, A D1 The first characteristic peak D corresponding to the (110) crystal plane of the positive electrode active material is represented by... 1 The peak area of ​​(110) satisfies 0.80 ≤ A D1 / A C1 ≤1.05.

[0016] In some embodiments of this disclosure, 0.85 ≤ A is satisfied. D1 / A C1 ≤1.00.

[0017] In some embodiments of this disclosure, S C1The first characteristic peak C corresponding to the (018) crystal plane of the positive electrode active material is indicated by... 1 The position of (018), S D1 The first characteristic peak D corresponding to the (110) crystal plane of the positive electrode active material is represented by... 1 The position of (110) satisfies 0.35°≤S D1 -S C1 ≤0.65°.

[0018] In some embodiments of this disclosure, 0.40°≤S is satisfied. D1 -S C1 ≤0.60°.

[0019] In some embodiments of this disclosure, I C2 The second characteristic peak C corresponding to the (018) crystal plane of the positive electrode active material is indicated. 2 The strength of (018), I D2 The second characteristic peak D corresponding to the (110) crystal plane of the positive electrode active material is represented by... 2 The strength of (110) satisfies 1.77≤Ic1 / I C2 ≤1.98, 1.78≤I D1 / I D2 ≤2.19.

[0020] In some embodiments of this disclosure, 1.80 ≤ Ic1 / I C2 ≤1.95, 1.80≤I D1 / I D2 ≤2.00.

[0021] In some embodiments of this disclosure, F C1 The first characteristic peak C corresponding to the (018) crystal plane of the positive electrode active material is indicated by... 1 The half-width of (018), F D1 The first characteristic peak D corresponding to the (110) crystal plane of the positive electrode active material is represented by... 1 The half-width of (110) satisfies 0° < F C1 ≤0.20°, 0°<F D1 ≤0.20°.

[0022] In some embodiments of this disclosure, 0.05°≤F is satisfied. C1 ≤0.15°, 0.05°≤F D1 ≤0.15°.

[0023] In some embodiments of this disclosure, the chemical formula of the positive electrode active material is Li. a (Ni x Co y Mnz M b R c O2, wherein 0.95≤a≤1.10, 0.50≤x≤0.95, 0≤y≤0.05, 0≤z≤0.45, 0≤b≤0.05, 0≤c≤0.03, and at least one of b and c is not equal to 0; M and R are independently selected from at least one of B, Mg, Sr, Ba, Fe, Cu, Ni, Co, Mn, Sc, Y, La, Ce, Sm, Eu, Gd, Tb, Dy, Yb, Lu, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ru, Rh, Ir, Zn, Al, Ga, In, Si, Pb, Cd, Ge, Sn, Sb, Bi, and Te.

[0024] In some embodiments of this disclosure, the positive electrode active material includes a matrix material and a coating layer, the coating layer being disposed on at least a portion of the surface of the matrix material.

[0025] In some embodiments of this disclosure, the covering layer includes a continuous covering layer and a covering material protruding from the surface of the continuous covering layer, the covering material including at least one of dot-shaped covering material and island-shaped covering material.

[0026] In some embodiments of this disclosure, the continuous coating layer comprises at least one of lithium cobalt oxide of Al, lithium cobalt oxide of W, lithium cobalt oxide of Zr, and lithium cobalt oxide of B; and / or, the coating comprises at least one of aluminum oxide, tungsten oxide, titanium oxide, boron oxide, strontium oxide, lithium oxide of Al, lithium oxide of W, lithium oxide of Ti, lithium oxide of B, and lithium oxide of Sr.

[0027] In a second aspect, this disclosure provides a method for preparing the above-mentioned positive electrode active material, comprising:

[0028] The nickel-cobalt-manganese precursor, the first lithium source, and the first doping additive are mixed according to the stoichiometric ratio and subjected to the first sintering to obtain the first sintered product.

[0029] The first sintered product, the second lithium source, and the optional second doping additive are mixed according to the stoichiometric ratio and then sintered a second time to obtain the second sintered product.

[0030] The second sintered product and the coating agent are mixed and sintered a third time to obtain the positive electrode active material.

[0031] According to the method for preparing the above-mentioned positive electrode active material according to the embodiments of this disclosure, by adding lithium source in batches during two sintering processes (i.e., adding a portion of lithium source in the first sintering and another portion of lithium source in the second sintering), the formation of impurity phases during the preparation of the single crystal matrix at high temperature and with excessive lithium source is prevented. Simultaneously, the generation of micro-stress is reduced, resulting in more complete single crystallization of the matrix material. Furthermore, doping additives are added during both sintering processes to obtain a structurally stable matrix material that combines both solid phase doping and surface doping. The surface of the matrix material is then coated to modify the interface, effectively isolating the positive electrode active material from direct contact with the electrolyte and reducing side reactions, thereby effectively improving the electrochemical performance and safety performance of the battery. Additionally, the ionic and electronic conductivity of the positive electrode material is effectively improved, thereby effectively increasing the battery's discharge capacity and cycle performance.

[0032] In some embodiments of this disclosure, the first sintering includes a first heating stage and a first isothermal stage, wherein the heating rate of the first heating stage is 1℃ / min to 15℃ / min, the temperature of the first isothermal stage is 600℃ to 1000℃, and the duration of the first isothermal stage is 2h to 20h; and / or, the second sintering includes a second heating stage, a third heating stage, and a second isothermal stage, wherein the heating rate of the second heating stage is greater than the heating rate of the third heating stage, and the difference between the heating rates of the second heating stage and the third heating stage is 1℃ / min to 5℃ / min, the temperature of the second isothermal stage is 600℃ to 1200℃, and the duration of the second isothermal stage is 2h to 24h.

[0033] In some embodiments of this disclosure, the first doping additive is selected from at least one of oxides and hydroxides containing doping element M; and / or, the second doping additive is selected from at least one of oxides and hydroxides containing doping element R; and / or, the first lithium source includes lithium carbonate, the second lithium source includes lithium hydroxide, and the molar ratio of the first lithium source to the second lithium source is (30-90):(10-70).

[0034] In some embodiments of this disclosure, the step of mixing the second sintering product and the coating agent and performing a third sintering includes the following steps: mixing the second sintering product and the first coating agent and performing a third sintering to obtain a third sintering product; mixing the third sintering product and the second coating agent and performing a fourth sintering to obtain a positive electrode active material.

[0035] In some embodiments of this disclosure, the third sintering includes a fourth heating stage and a third isothermal stage, wherein the heating rate of the fourth heating stage is 1℃ / min to 15℃ / min, the temperature of the third isothermal stage is 500℃ to 1000℃, and the duration of the third isothermal stage is 2h to 20h; and / or, the fourth sintering includes a fifth heating stage and a fourth isothermal stage, wherein the heating rate of the fifth heating stage is 1℃ / min to 15℃ / min, the temperature of the fourth isothermal stage is 200℃ to 800℃, and the duration of the fourth isothermal stage is 2h to 20h.

[0036] In some embodiments of this disclosure, the first coating agent is selected from at least one of oxides, hydroxides, and carbonates containing Al, W, Zr, or B; and / or, the second coating agent is selected from at least one of oxides, hydroxides, and carbonates containing Al, W, Ti, B, or Sr; and / or, the mass of the first coating agent is 0.01% to 2% of the mass of the second sintered product; and / or, the mass of the second coating agent is 0.01% to 2% of the mass of the third sintered product.

[0037] In a third aspect, this disclosure provides a positive electrode sheet. According to embodiments of this disclosure, the positive electrode sheet comprises the positive electrode active material described in the first aspect of this disclosure.

[0038] In a fourth aspect, this disclosure provides a battery. According to an embodiment of this disclosure, the battery includes the positive electrode sheet described in the third aspect of this disclosure.

[0039] In a fifth aspect of this disclosure, an electrical appliance is provided. According to an embodiment of this disclosure, the electrical appliance includes the battery described in the fourth aspect of this disclosure.

[0040] Additional aspects and advantages of this disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this disclosure. Attached Figure Description

[0041] Figure 1 is the XRD pattern of the low cobalt layered cathode material of Example 3 and Comparative Example 4;

[0042] Figure 2 is a SEM image of Example 1 after four sintering processes;

[0043] Figure 3 shows the cycle retention of batteries made from the low-cobalt layered cathode materials of Examples 1, 3, 4, 7 and Comparative Example 1. Detailed Implementation

[0044] Embodiments of this disclosure are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this disclosure, and should not be construed as limiting this disclosure.

[0045] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0046] This disclosure was made by the inventors based on the following questions:

[0047] The inventors discovered that in nickel-cobalt-manganese ternary layered materials, reducing the proportion of cobalt leads to severe Li / Ni mixing in the cathode material, poor electronic conductivity, and slow lithium-ion migration. This, in turn, results in decreased initial charge / discharge efficiency, poor rate performance, deteriorated cycle performance, and increased impedance, severely hindering the promotion and application of low-cobalt and cobalt-free layered cathode materials. Therefore, how to eliminate the adverse effects of cobalt removal on the structure and performance of cathode materials, enabling them to achieve high energy density and maintain good structural stability during electrochemical cycling, is the technical challenge that this disclosure aims to solve.

[0048] In view of this, in one aspect of this disclosure, a positive electrode active material is proposed. According to an embodiment of this disclosure, the above-mentioned positive electrode active material has a specific structure, and in the XRD pattern of the above-mentioned positive electrode active material, the characteristic peak C(018) corresponding to the (018) crystal plane of the positive electrode active material exhibits a double-peak distribution, including a first characteristic peak C located on the small-angle side. 1 (018) and the second characteristic peak C on the large angle side 2 (018); The characteristic peak D(110) corresponding to the (110) crystal plane of the positive electrode active material exhibits a bimodal distribution, including the first characteristic peak D located on the small angle side. 1 (110) and the second characteristic peak D on the large angle side 2 (110). I C1 The first characteristic peak C corresponding to the (018) crystal plane of the positive electrode active material is indicated. 1 The strength of (018), I D1 The first characteristic peak D corresponding to the (110) crystal plane of the positive electrode active material is represented by... 1 The intensity of (110), as measured by XRD, shows that the intensity ratio of the diffraction peaks satisfies the following relationship: 0.80 ≤ I D1 / I C1 ≤1.00. Because the (110) crystal facets of the positive electrode active material have high activity, excessive exposure of the (110) crystal facets can easily lead to irreversible phase transitions in the positive electrode material during cycling, transforming it from a layered structure to a spinel phase (space group Fd-3m), and then to a rock salt phase (space group Fm-3m), thereby causing a deterioration in the cycle stability of the battery. This disclosure addresses this issue by using 0.80≤I D1 / I C1 By controlling the value ≤1.00 within the above range, the exposure of active crystal faces can be appropriately reduced, effectively suppressing side reactions and surface phase transitions between the cathode material and the electrolyte, thereby effectively improving the cycle stability of the cathode material under high voltage. Preferably, 0.85≤I D1 / I C1 ≤0.95. This disclosure effectively improves the structural and interfacial stability of the positive electrode active material, while also effectively reducing the Li / Ni mixing degree of the positive electrode material, thereby effectively improving the battery's cycle performance, first charge-discharge efficiency, discharge capacity, and safety performance, and also effectively reducing the battery's initial impedance and impedance increase.

[0049] According to some specific embodiments of this disclosure, S C1 The first characteristic peak C corresponding to the (018) crystal plane of the positive electrode active material is indicated. 1 The position of (018), S D1 The first characteristic peak D corresponding to the (110) crystal plane of the positive electrode active material is represented by... 1 The position of (110) satisfies 0.35°≤S D1 -S C1 The greater the splitting degree of the characteristic peak C(018) corresponding to the (018) crystal plane and the characteristic peak D(110) corresponding to the (110) crystal plane of the positive electrode active material, the more obvious the layered characteristics of the positive electrode material and the lower the degree of Li / Ni mixing. This disclosure controls the splitting degree of the characteristic peak C(018) and the characteristic peak D(110) to be within 0.35° ≤ 0.65°. D1 -S C1 Within the range of ≤0.65°, layered cathode materials with high capacity and excellent cycle performance can be obtained. Preferably, 0.40° ≤ S D1 -S C1 ≤0.60°.

[0050] According to some further specific embodiments of this disclosure, A C1 The first characteristic peak C corresponding to the (018) crystal plane of the positive electrode active material is indicated. 1 (018) peak area, A D1 The first characteristic peak D corresponding to the (110) crystal plane of the positive electrode active material is represented by... 1The peak area of ​​(110), as measured by XRD, satisfies the following relationship: 0.80≤A D1 / A C1 ≤1.05. Because the (110) crystal facets of the positive electrode active material have high activity, excessive exposure of the (110) crystal facets can easily lead to irreversible phase transitions in the positive electrode material during cycling, transforming it from a layered structure to a spinel phase (space group Fd-3m), and then to a rock salt phase (space group Fm-3m), thereby causing a deterioration in the cycle stability of the battery. This disclosure uses 0.80≤A D1 / A C1 By controlling the value ≤1.05 within the above range, the exposure of active crystal faces can be further reduced, and the side reactions and surface phase transitions between the cathode material and the electrolyte can be further effectively suppressed, thereby further improving the cycle stability of the cathode material under high voltage. Preferably, 0.85≤A is satisfied. D1 / A C1 ≤1.00.

[0051] According to some further specific embodiments of this disclosure, I C2 The second characteristic peak C corresponding to the (018) crystal plane of the positive electrode active material is indicated. 2 The strength of (018), I D2 The second characteristic peak D corresponding to the (110) crystal plane of the positive electrode active material is represented by... 2 The strength of (110) satisfies 1.77≤Ic1 / I C2 ≤1.98, 1.78≤I D1 / I D2 ≤2.19. Second characteristic peak C 2 (018) and D 2 (110) The diffraction peaks originate from multiphase diffraction, if C 2 (018) and D 2 If the proportion of (110) is too high, it can easily lead to a decrease in the capacity, initial efficiency, and cycle characteristics of the battery; at the same time, C 2 (018) and D 2 When the proportion of (110) is too low, the crystallinity of the positive electrode active material is poor, which will also cause the performance of the battery to deteriorate, such as cycle life and DCR increase. The inventors discovered that by increasing the proportion of the first characteristic peak C 1 (018) and the second characteristic peak C 2 The intensity ratio of (018) and the first characteristic peak D 1 (110) and the second characteristic peak D 2 The intensity ratio of (110) is within the specified range, indicating that the positive electrode active material exhibits good battery performance. Preferably, it satisfies 1.80 ≤ Ic1 / I C2 ≤1.95, 1.80≤I D1 / I D2 ≤2.00.

[0052] According to some further specific embodiments of this disclosure, F C1 The first characteristic peak C corresponding to the (018) crystal plane of the positive electrode active material is indicated. 1 The half-width of (018), F D1 The first characteristic peak D corresponding to the (110) crystal plane of the positive electrode active material is represented by... 1 The half-width of (110) satisfies 0° < F C1 ≤0.20°, 0°<F D1 ≤0.20°. The smaller the grain size, the larger the full width at half maximum (FWHM) of the diffraction peak. Therefore, this disclosure limits 0° to <0.20°. C1 ≤0.20°, 0°<F D1 A deviation of ≤0.20° can effectively eliminate randomly oriented grain boundaries, reduce the contact area between the cathode material and the electrolyte, and achieve higher mechanical strength. It can effectively suppress microcracks in particles and the generation of harmful surface phase transitions / side reactions, thereby contributing to improved battery cycle stability. Preferably, 0.05° ≤ F C1 ≤0.15°, 0.05°≤F D1 ≤0.15°.

[0053] Half-peak width: The straight-line distance from one half-peak point to the other half-peak point of a peak. Half-peak value: Half the peak intensity. Peak value: The top or highest intensity point of a peak.

[0054] According to some specific embodiments of this disclosure, the chemical formula of the above-mentioned positive electrode active material is Li a (Ni x Co y Mn z M b R cO2, where 0.95≤a≤1.10 (as an example, a can be 0.95 / 1.00 / 1.05 / 1.10, etc.), 0.50≤x≤0.95 (as an example, x can be 0.50 / 0.60 / 0.70 / 0.80 / 0.90 / 0.95, etc.), 0≤y≤0.05 (as an example, y can be 0 / 0.01 / 0.02 / 0.03 / 0.04 / 0.05), 0 ≤z≤0.45 (for example, z can be 0 / 0.05 / 0.10 / 0.20 / 0.30 / 0.40 / 0.45), 0≤b≤0.05 (for example, b can be 0 / 0.01 / 0.02 / 0.03 / 0.04 / 0.05), 0≤c≤0.03 (for example, c can be 0 / 0.01 / 0.02 / 0.03), and at least one of b and c is not equal to 0; M and R are independently selected from at least one of B, Mg, Sr, Ba, Fe, Cu, Ni, Co, Mn, Sc, Y, La, Ce, Sm, Eu, Gd, Tb, Dy, Yb, Lu, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ru, Rh, Ir, Zn, Al, Ga, In, Si, Pb, Cd, Ge, Sn, Sb, Bi, and Te. Therefore, the above-mentioned positive electrode active material includes doping elements M and R, thereby obtaining a structurally stable matrix material that combines both solid phase doping and surface doping. This can effectively improve the structural stability and interface stability of the positive electrode active material, and at the same time reduce the Li / Ni mixing degree of the positive electrode material, thereby effectively improving the cycle performance, discharge capacity and safety performance of the battery.

[0055] According to some preferred embodiments of this disclosure, 1.00≤a≤1.05, 0.60≤x≤0.80, 0≤y≤0.03, 0.05≤z≤0.30, 0.01≤b≤0.03, 0≤c≤0.02, x+y+z+b+c=1.

[0056] According to some preferred embodiments of this disclosure, M and R are not the same. M is selected from at least one of B, Mg, Fe, Cu, Ni, Co, Mn, Sc, Ti, Zr, Cr, Zn, Al, Ga, In, Si, Pb, Ge, Sn, and Sb, more preferably at least one of B, Mg, Ti, Zr, Zn, Al, and Si. R is selected from at least one of Sr, Ba, Y, La, Ce, Sm, Eu, Gd, Tb, Dy, Yb, Lu, Hf, V, Nb, Ta, Mo, W, Ru, Rh, Ir, Cd, Bi, and Te, more preferably at least one of Sr, Ba, Y, La, Al, Nb, Ta, Mo, and W. The above-mentioned doping elements M and R can further effectively improve the structural stability and interfacial stability of the positive electrode active material, and can also further reduce the Li / Ni mixing degree of the positive electrode material, thereby further effectively improving the cycle performance, discharge capacity, and safety performance of the battery.

[0057] According to some specific embodiments of this disclosure, the positive electrode active material includes a matrix material and a coating layer, wherein the coating layer is disposed on at least a portion of the surface of the matrix material. Thus, by providing a coating layer on the surface of the matrix material to modify the interface of the matrix material, on the one hand, direct contact between the positive electrode active material and the electrolyte can be effectively isolated, reducing side reactions and thereby effectively improving the electrochemical performance and safety performance of the battery; on the other hand, the ionic and electronic conductivity of the positive electrode material can also be effectively improved, thereby effectively improving the battery's initial charge-discharge efficiency, discharge capacity, and cycle performance, while reducing the battery's initial impedance and impedance increase.

[0058] According to further embodiments of this disclosure, the coating layer includes a continuous coating layer and coatings protruding from the surface of the continuous coating layer. The coatings include at least one of dot-like coatings and island-like coatings. The continuous coating layer can effectively improve the ionic and electronic conductivity of the cathode material, thereby increasing the battery's discharge capacity and cycle performance while reducing the battery's impedance. The discontinuous coatings can effectively improve the stability of the cathode material, reduce the reaction between the cathode material and the electrolyte, and effectively improve the ionic and electronic conductivity of the cathode material, thereby improving the battery's charge-discharge performance.

[0059] It is understandable that a continuous coating layer refers to a coating layer with a smooth and continuous surface, without obvious particles or dot-like / island-like coatings. Dot-like / island-like coatings refer to coatings that are clearly protruding from the surface of the coating layer and are in the form of dots and / or islands.

[0060] According to some specific embodiments of this disclosure, the continuous coating layer includes at least one of lithium cobalt oxide of Al, lithium cobalt oxide of W, lithium cobalt oxide of Zr, and lithium cobalt oxide of B. Thus, the continuous coating layer can further effectively improve the ionic and electronic conductivity of the cathode material, thereby further improving the discharge capacity and cycle performance of the battery, while further reducing the impedance of the battery.

[0061] According to further embodiments of this disclosure, the coating material includes at least one selected from aluminum oxide, tungsten oxide, titanium oxide, boron oxide, strontium oxide, lithium oxide of Al, lithium oxide of W, lithium oxide of Ti, lithium oxide of B, and lithium oxide of Sr. Therefore, the above-mentioned coating material can further improve the stability of the cathode material, further reduce the reaction between the cathode material and the electrolyte, and further effectively improve the ionic and electronic conductivity of the cathode material, thereby further improving the charge-discharge performance of the battery.

[0062] According to some specific embodiments of this disclosure, the thickness of the continuous coating layer ranges from 0.1 μm to 0.5 μm. The height of the coating protruding from the surface of the coating layer ranges from 0.1 μm to 0.5 μm.

[0063] In a second aspect, this disclosure provides a method for preparing the above-mentioned positive electrode active material. According to embodiments of this disclosure, the method includes:

[0064] S100: The nickel-cobalt-manganese precursor, the first lithium source, and the first doping additive are mixed according to the stoichiometric ratio and sintered for the first time to obtain the first sintered product.

[0065] In this step, the nickel-cobalt-manganese precursor, the first lithium source, and the first dopant are mixed in stoichiometric proportions, and then subjected to a first sintering under air / oxygen conditions. The resulting product is then crushed to obtain a bulk-doped first sintered product. This first sintered product is a compound containing lithium, nickel, cobalt, manganese, and the first dopant element, and at this stage, the compound has relatively small grains. By doping the positive electrode active material with the first dopant, the structural stability of the positive electrode active material can be effectively improved, and the Li / Ni mixing degree of the positive electrode material can also be reduced, thereby effectively improving the cycle performance, capacity, and suppressing gas generation of the battery.

[0066] In embodiments of this disclosure, the aforementioned nickel-cobalt-manganese precursor is a hydroxide solid solution containing nickel-cobalt-manganese.

[0067] According to some specific embodiments of this disclosure, the first doping additive is selected from at least one oxide and hydroxide containing a dopant element M, wherein M is selected from at least one of B, Mg, Sr, Ba, Fe, Cu, Ni, Co, Mn, Sc, Y, La, Ce, Sm, Eu, Gd, Tb, Dy, Yb, Lu, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ru, Rh, Ir, Zn, Al, Ga, In, Si, Pb, Cd, Ge, Sn, Sb, Bi, and Te. The above-mentioned first doping additives can effectively improve the structural stability of the positive electrode active material and reduce the Li / Ni mixing degree of the positive electrode material.

[0068] According to some specific embodiments of this disclosure, the first sintering includes a first heating stage and a first isothermal stage. The heating rate of the first heating stage is 1℃ / min to 15℃ / min (examples include 1℃ / min, 3℃ / min, 5℃ / min, 7℃ / min, 10℃ / min, 12℃ / min, 15℃ / min, etc.). This ensures both heating efficiency and sufficient removal of impurity elements from the first lithium source and the first doped additive from the reaction system.

[0069] According to some specific embodiments of this disclosure, the temperature of the first isothermal stage is 600℃~1000℃ (for example, it can be 600℃, 700℃, 800℃, 900℃, 1000℃, etc.), and the time of the first isothermal stage is 2h~20h (for example, it can be 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, etc.), thereby further ensuring that the nickel-cobalt-manganese precursor, the first lithium source, and the first doping additive react fully to form the bulk-doped first sintered product.

[0070] S200: The first sintered product, the second lithium source, and the optional second doping additive are mixed according to the stoichiometric ratio and then sintered for a second time to obtain the second sintered product.

[0071] In this step, the first sintered product, the second lithium source, and an optional second dopant are mixed in stoichiometric proportions, followed by a second sintering under air / oxygen conditions. The resulting product is then crushed to obtain a single-crystal low-cobalt or cobalt-free matrix material (i.e., the second sintered product). In this step, the second dopant element and the second lithium source are mainly doped onto the surface layer of the material. By doping the positive electrode active material with the second dopant, the interfacial stability of the positive electrode active material can be effectively improved, thereby improving the cycle performance of the battery and suppressing gas generation. Simultaneously, this step is a grain growth process, where the aforementioned second sintered product grows into a relatively large single crystal.

[0072] According to further embodiments of this disclosure, the second doping additive is selected from at least one oxide and hydroxide containing the doping element R, wherein R is selected from at least one of B, Mg, Sr, Ba, Fe, Cu, Ni, Co, Mn, Sc, Y, La, Ce, Sm, Eu, Gd, Tb, Dy, Yb, Lu, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ru, Rh, Ir, Zn, Al, Ga, In, Si, Pb, Cd, Ge, Sn, Sb, Bi, and Te. The aforementioned types of second doping additives can further effectively improve the interfacial stability of the positive electrode active material, thereby improving the cycle performance of the battery and suppressing gas generation.

[0073] According to some specific embodiments of this disclosure, the first lithium source includes lithium carbonate, and the second lithium source includes lithium hydroxide. This disclosure, by adding lithium sources in batches during two sintering processes, with lithium carbonate added in the first sintering and lithium hydroxide added in the second sintering, can effectively prevent the formation of impurity phases during the preparation of a single-crystal matrix at high temperatures and with excessive lithium sources. It can also reduce the generation of micro-stress, resulting in more complete single-crystalization of the matrix material. Further, the molar ratio of the first lithium source to the second lithium source is (30–90):(10–70), thereby further effectively promoting the single-crystalization of the matrix material. Preferably, the molar ratio of the first lithium source to the second lithium source is (40–90):(10–60), more preferably (50–90):(20–60).

[0074] According to some specific embodiments of this disclosure, the second sintering includes a second heating stage, a third heating stage, and a second isothermal stage. The heating rate of the second heating stage is greater than that of the third heating stage, and the difference between the heating rates of the second and third heating stages is 1°C / min to 5°C / min. The heating rate of the second heating stage can be 3°C / min to 10°C / min (examples include 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, etc.), and the heating rate of the third heating stage can be 1°C / min to 5°C / min (examples include 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min). By limiting the heating rate of the second heating stage to the above range, it is beneficial to ensure that impurity elements in the second lithium source and the second doping additive are fully discharged from the reaction system. By limiting the heating rate of the third heating stage to the above range, it is beneficial to the growth of cathode material grains.

[0075] According to some specific embodiments of this disclosure, the temperature of the second isothermal stage is 600℃~1200℃ (examples include 600℃, 700℃, 800℃, 900℃, 1000℃, 1100℃, 1200℃, etc.), and the time of the second isothermal stage is 2h~24h (examples include 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, etc.). This can further ensure that the first sintering product, the second lithium source, and the second doping additive react fully to form a structurally stable matrix material that combines solid phase doping and surface doping.

[0076] S300: The second sintering product and the coating agent are mixed and sintered for the third time to obtain the positive electrode active material;

[0077] According to some specific embodiments of this disclosure, step S300 above includes:

[0078] S310: Mix the second sintered product and the first coating agent, and perform a third sintering to obtain the third sintered product;

[0079] In this step, the second sintered product and the first coating agent are mixed, and then a third sintering is performed in air / oxygen to form a continuous coating layer on at least a portion of the surface of the matrix material. The resulting product is then crushed to obtain the third sintered product. By forming a continuous coating layer on the surface of the matrix material, the ionic and electronic conductivity of the cathode material can be effectively improved, thereby increasing the battery's discharge capacity and cycle performance while reducing the battery's impedance.

[0080] According to some specific embodiments of this disclosure, the first coating agent is selected from at least one of oxides, hydroxides, and carbonates containing Al, W, Zr, or B, such as aluminum oxide, aluminum hydroxide, aluminum carbonate, etc., and the first coating agent is sintered to form a lithium cobalt oxide containing Al, W, Zr, or B.

[0081] According to some specific embodiments of this disclosure, the mass of the first coating agent is 0.01% to 2% of the mass of the second sintered product. For example, it can be 0.01%, 0.5%, 1%, 1.5%, 2%, etc., thereby further effectively improving the ionic and electronic conductivity of the cathode material.

[0082] According to some specific embodiments of this disclosure, the third sintering includes a fourth heating stage and a third isothermal stage. The heating rate of the fourth heating stage is 1℃ / min to 15℃ / min (examples include 1℃ / min, 3℃ / min, 5℃ / min, 7℃ / min, 10℃ / min, 12℃ / min, 15℃ / min, etc.). This ensures both heating efficiency and sufficient removal of impurity elements from the first coating agent from the reaction system.

[0083] According to some specific embodiments of this disclosure, the temperature of the third isothermal stage is 500℃ to 1000℃ (examples include 500℃, 600℃, 700℃, 800℃, 900℃, 1000℃, etc.), and the time of the third isothermal stage is 2h to 20h (examples include 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, etc.), thereby further ensuring that the first coating agent reacts fully to form a continuous coating layer.

[0084] S320: The third sintering product and the second coating agent are mixed and sintered for the fourth time to obtain the positive electrode active material;

[0085] In this step, the third sintering product and the second coating agent are mixed, and then a fourth sintering is performed under air / oxygen to form a discontinuous coating on a portion of the surface of the continuous coating layer. This coating protrudes from the surface of the continuous coating layer and includes at least one of dot-like and island-like coatings. Finally, the obtained product is crushed, cooled, sieved, and demagnetized to obtain the positive electrode active material. By forming a discontinuous coating on the surface of the continuous coating layer, the stability of the positive electrode material can be effectively improved, the reaction between the positive electrode material and the electrolyte can be reduced, and the ionic and electronic conductivity of the positive electrode material can be effectively improved, thereby improving the charge and discharge performance of the battery.

[0086] According to some specific embodiments of this disclosure, the second coating agent is selected from at least one of oxides, hydroxides, and carbonates containing Al, W, Ti, B, or Sr, such as aluminum oxide, aluminum hydroxide, aluminum carbonate, etc., and the second coating agent is sintered to form aluminum oxide or lithium oxide containing Al, W, Ti, B, or Sr.

[0087] According to some specific embodiments of this disclosure, the mass of the second coating agent is 0.01% to 2% of the mass of the third sintered product. Examples include 0.01%, 0.5%, 1%, 1.5%, 2%, etc., which can further ensure the improvement of the stability of the cathode material and further effectively improve the ionic and electronic conductivity of the cathode material.

[0088] According to some specific embodiments of this disclosure, the fourth sintering includes a fifth heating stage and a fourth isothermal stage. The heating rate of the fifth heating stage is 1℃ / min to 15℃ / min (examples include 1℃ / min, 3℃ / min, 5℃ / min, 7℃ / min, 10℃ / min, 12℃ / min, 15℃ / min, etc.). This ensures both heating efficiency and sufficient removal of impurity elements from the second coating agent from the reaction system.

[0089] The temperature of the fourth isothermal stage is 200℃ to 800℃ (examples include 200℃, 300℃, 400℃, 500℃, 600℃, 700℃, 800℃, etc.), and the duration of the fourth isothermal stage is 2h to 20h (examples include 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, etc.). This further ensures that the second coating agent reacts fully to form a discontinuous coating.

[0090] Therefore, this disclosure prevents the formation of impurity phases during the preparation of single-crystal substrates at high temperatures and with excessive lithium sources by adding lithium sources in batches during two sintering processes (i.e., adding a portion of lithium source in the first sintering and another portion in the second sintering). This also reduces the generation of micro-stress, resulting in more complete single-crystalization of the substrate material. Furthermore, doping additives are added during both sintering processes to obtain a structurally stable substrate material that combines both solid phase doping and surface doping. The substrate material surface is then coated to modify the interface, effectively isolating the positive electrode active material from direct contact with the electrolyte and reducing side reactions, thereby improving the electrochemical and safety performance of the battery. Additionally, it effectively improves the ionic and electronic conductivity of the positive electrode material, thus enhancing the battery's discharge capacity and cycle performance.

[0091] In a third aspect of this disclosure, a positive electrode sheet is provided. According to an embodiment of this disclosure, the positive electrode sheet includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector. The positive active material layer includes the positive active material described in the first aspect of this disclosure, or a positive active material prepared using the method described in the second aspect.

[0092] According to embodiments of this disclosure, the positive electrode sheet includes a positive current collector and a positive active material layer disposed on the positive current collector. The positive active material layer includes the aforementioned positive active material. The positive current collector can be a metal foil or a composite current collector (a metal material can be disposed on a polymer substrate to form a composite current collector). For example, the positive current collector can be an aluminum foil.

[0093] According to some embodiments of this disclosure, the positive electrode active material layer may optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a terpolymer of PVDF-tetrafluoroethylene-propylene, a terpolymer of PVDF-hexafluoropropylene-tetrafluoroethylene, a tetrafluoroethylene-hexafluoropropylene copolymer, or a fluorinated acrylate resin.

[0094] According to some embodiments of this disclosure, the positive electrode active material layer may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0095] According to some embodiments of this disclosure, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto a positive current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0096] It should be noted that the features and advantages described above for the positive electrode active material and its preparation method also apply to this positive electrode sheet, and will not be repeated here.

[0097] In a fourth aspect, this disclosure provides a battery. According to embodiments of this disclosure, the battery includes at least one of the positive electrode plates from the third aspect. This effectively improves the battery's initial charge / discharge efficiency, discharge capacity, cycle performance, and safety performance, while reducing the battery's initial impedance and impedance increase.

[0098] As an example, a battery includes a positive electrode, a negative electrode, an electrolyte, and a separator, with the separator located between the positive and negative electrodes. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0099] According to embodiments of this disclosure, the negative electrode sheet includes a negative current collector and a negative active material layer disposed on the negative current collector. The negative active material layer includes a negative active material. The negative current collector can be a metal foil or a composite current collector (a metal material can be disposed on a polymer substrate to form a composite current collector). For example, the positive current collector can be a copper foil.

[0100] According to some embodiments of this disclosure, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and sodium titanate, etc.

[0101] According to some embodiments of this disclosure, the negative electrode active material layer may optionally include a conductive agent. The conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0102] According to some embodiments of this disclosure, the negative electrode active material layer may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0103] According to some embodiments of this disclosure, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative electrode active material, conductive agent, and binder, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto a negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing, and other processes.

[0104] According to some other embodiments of this disclosure, the negative electrode may include a sodium sheet or a sodium alloy, such as a sodium-indium alloy.

[0105] According to some embodiments of this disclosure, the type of separator is not particularly limited, and any known porous separator with good chemical and mechanical stability can be selected. As an example, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, or polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0106] According to some embodiments of this disclosure, there are no specific limitations on the type of electrolyte, which can be selected according to requirements. According to some specific embodiments of this disclosure, the electrolyte is an electrolyte solution, which includes a lithium salt and a solvent.

[0107] According to some specific embodiments of this disclosure, lithium salts may include lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium bis(fluorosulfonyl)imide (LiFSI), lithium phosphate (LiBOB), and lithium difluorophosphate (LiPO2F2).

[0108] According to some specific embodiments of this disclosure, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethylene glycol dimethyl ether, methyl ethyl sulfone, or diethyl sulfone.

[0109] In some embodiments of this disclosure, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0110] It should be noted that the features and advantages described above for the positive electrode also apply to this solid-state battery, and will not be repeated here.

[0111] In a fifth aspect, this disclosure provides an electrical device. According to an embodiment of this disclosure, the electrical device includes the battery described above. The features and advantages described above for the battery also apply to this electrical device, and will not be repeated here.

[0112] Specifically, the aforementioned electrical equipment can include, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0113] The following describes embodiments of this disclosure. The embodiments described below are exemplary and are only used to explain this disclosure, and should not be construed as limiting this disclosure. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0114] Example 1

[0115] (1) Lithium carbonate, nickel cobalt manganese precursor, and zirconium oxide are uniformly mixed in a high-speed mixer in a ratio of n(Li):n(Ni):n(Co):n(Mn):n(Zr)=0.52:0.763:0.015:0.219:0.003 to obtain mixture I;

[0116] (2) Mixture I was heated to 875°C at 5.5°C / min in air atmosphere, held at the temperature for 8.5h, and naturally cooled to room temperature. The mixture was then crushed by a colloid mill to obtain process product I, with a D50 of 4.2μm.

[0117] (3) Process product I and lithium hydroxide are mixed according to n(Li 0.52 Ni 0.763 Co 0.015 Mn 0.219 Zr 0.003 The mixtures were homogeneously mixed in a high-speed mixer at a ratio of 1:0.52 (n(Li) = 1:0.52) to obtain mixture II.

[0118] (4) Mixture II was sintered for the second time under an oxygen atmosphere by heating to 650°C at 4.5°C / min and then heating to 920°C at 2.5°C / min, holding for 8 hours, and then naturally cooling to room temperature. After crushing, process product II was obtained.

[0119] (5) Process product II is mixed with alumina and cobalt hydroxyoxide in a high-speed mixer at a mass ratio of 100:0.19:0.76 to obtain mixture III;

[0120] (6) The third sintering was carried out in air, the temperature was increased to 750℃ at 3℃ / min, held for 8h, cooled naturally to room temperature, and the obtained product was crushed to obtain process product III;

[0121] (7) Process product III is mixed with alumina, tungsten oxide and titanium oxide in a mass ratio of 100:0.28:0.25:0.30 in a high-speed mixer to obtain mixture IV;

[0122] (8) A fourth sintering process was performed in air, with the temperature increased to 410℃ at a rate of 3℃ / min, held for 8 hours, and then naturally cooled to room temperature. The resulting product was crushed and passed through a 400-mesh sieve to obtain a low-cobalt layered cathode material Al, whose composition is Li. 1.04 Ni 0.747 Co 0.023 Mn 0.214 Zr 0.003 Al 0.009 W 0.001 Ti 0.003 O2.

[0123] Example 2

[0124] (1) Lithium carbonate, nickel cobalt manganese precursor, zirconium oxide, and aluminum oxide are uniformly mixed in a high-speed mixer in the ratio of n(Li):n(Ni):n(Co):n(Mn):n(Zr):n(Al)=0.78:0.761:0.015:0.219:0.002:0.003 to obtain mixture I;

[0125] (2) Mixture I was heated to 895℃ at 5.5℃ / min under an oxygen atmosphere, held at the temperature for 8.5h, and then naturally cooled to room temperature. The mixture was then crushed by a colloid mill to obtain process product I with a D50 of 4.5μm.

[0126] (3) Process product I and lithium hydroxide are mixed according to n(Li 0.78 Ni 0.761 Co 0.015 Mn 0.219 Zr 0.002 Al 0.003 The mixtures of O2 and n(Li) in a ratio of 1:0.26 were uniformly mixed in a high-speed mixer to obtain mixture II.

[0127] (4) Mixture II was sintered for the second time under an oxygen atmosphere by heating to 650°C at 4.5°C / min and then heating to 900°C at 2.5°C / min, holding for 8 hours, and then cooling naturally to room temperature. After crushing, process product II was obtained.

[0128] (5) Process product II is mixed with alumina and cobalt hydroxyoxide in a high-speed mixer at a mass ratio of 100:0.19:0.76 to obtain mixture III;

[0129] (6) The third sintering was carried out in air, the temperature was increased to 750℃ at 3℃ / min, held for 8h, cooled naturally to room temperature, and the obtained product was crushed to obtain process product III;

[0130] (7) Process product III is mixed with alumina, tungsten oxide and titanium oxide in a mass ratio of 100:0.28:0.25:0.30 in a high-speed mixer to obtain mixture IV;

[0131] (8) A fourth sintering process was performed in air, with the temperature increased to 410℃ at a rate of 3℃ / min, held for 8 hours, and then naturally cooled to room temperature. The resulting product was crushed and passed through a 400-mesh sieve to obtain a low-cobalt layered cathode material A2, whose composition is Li. 1.04 Ni 0.745 Co 0.023 Mn 0.214 Zr 0.002 Al 0.012 W 0.001 Ti 0.003 O2.

[0132] Example 3

[0133] (1) Lithium carbonate, nickel cobalt manganese precursor, zirconium oxide, and aluminum oxide are uniformly mixed in a high-speed mixer in the ratio of n(Li):n(Ni):n(Co):n(Mn):n(Zr):n(Al)=0.78:0.761:0.015:0.219:0.002:0.003 to obtain mixture I;

[0134] (2) Mixture I was heated to 895℃ at 5.5℃ / min under an oxygen atmosphere, held at the temperature for 8.5h, and then naturally cooled to room temperature. The mixture was then crushed by a colloid mill to obtain process product I with a D50 of 4.5μm.

[0135] (3) Process product I, lithium hydroxide, and yttrium oxide are mixed according to n(Li 0.78 Ni 0.761 Co 0.015 Mn 0.219 Zr 0.002 Al 0.003The mixture of O2):n(Li):n(Y) in a ratio of 1:0.26:0.002 was uniformly mixed in a high-speed mixer to obtain mixture II.

[0136] (4) Mixture II was sintered for the second time under an oxygen atmosphere by heating to 650°C at 4.5°C / min and then heating to 900°C at 2.5°C / min, holding for 8 hours, and then cooling naturally to room temperature. After crushing, process product II was obtained.

[0137] (5) Process product II is mixed with alumina and cobalt hydroxyoxide in a high-speed mixer at a mass ratio of 100:0.19:0.76 to obtain mixture III;

[0138] (6) The third sintering was carried out in air, the temperature was increased to 750℃ at 3℃ / min, held for 8h, cooled naturally to room temperature, and the obtained product was crushed to obtain process product III;

[0139] (7) Process product III is mixed with alumina, tungsten oxide and titanium oxide in a mass ratio of 100:0.28:0.25:0.30 in a high-speed mixer to obtain mixture IV;

[0140] (8) A fourth sintering process was performed in air, with the temperature increased to 410℃ at a rate of 3℃ / min, held for 8 hours, and then naturally cooled to room temperature. The resulting product was crushed and passed through a 400-mesh sieve to obtain a low-cobalt layered cathode material A3, whose composition is Li. 1.04 Ni 0.744 Co 0.022 Mn 0.214 Zr 0.002 Y 0.002 Al 0.012 W 0.001 Ti 0.003 O2.

[0141] Example 4

[0142] (1) Lithium carbonate, nickel cobalt manganese precursor, zirconium oxide, and aluminum oxide are uniformly mixed in a high-speed mixer in the ratio of n(Li):n(Ni):n(Co):n(Mn):n(Zr):n(Al)=0.78:0.761:0.015:0.219:0.002:0.003 to obtain mixture I;

[0143] (2) Mixture I was heated to 895℃ at 5.5℃ / min under an oxygen atmosphere, held at the temperature for 8.5h, and then naturally cooled to room temperature. The mixture was then crushed by a colloid mill to obtain process product I with a D50 of 4.5μm.

[0144] (3) Process product I, lithium hydroxide, and yttrium oxide are mixed according to n(Li 0.78 Ni 0.761 Co0.015 Mn 0.219 Zr 0.002 Al 0.003 The mixture of O2):n(Li):n(Y) in a ratio of 1:0.26:0.002 was uniformly mixed in a high-speed mixer to obtain mixture II.

[0145] (4) Mixture II was sintered for the second time under an oxygen atmosphere by heating to 650°C at 4.5°C / min and then heating to 900°C at 2.5°C / min, holding for 8 hours, and then cooling naturally to room temperature. After crushing, process product II was obtained.

[0146] (5) Process product II is mixed with alumina, tungsten oxide and titanium oxide in a mass ratio of 100:0.28:0.25:0.30 in a high-speed mixer to obtain mixture III;

[0147] (6) A third sintering was performed in air, with the temperature increased to 410℃ at a rate of 3℃ / min, held for 8 hours, and then naturally cooled to room temperature. The resulting product was crushed and passed through a 400-mesh sieve to obtain a low-cobalt layered cathode material A4, whose composition is Li. 1.04 Ni 0.753 Co 0.015 Mn 0.216 Zr 0.002 Y 0.002 Al 0.008 W 0.001 Ti 0.003 O2.

[0148] Example 5

[0149] (1) Lithium carbonate, nickel cobalt manganese precursor, zirconium oxide, aluminum oxide and boron oxide are uniformly mixed in a high-speed mixer in the proportion of n(Li):n(Ni):n(Co):n(Mn):n(Zr):n(Al):n(B)=0.832:0.757:0.015:0.218:0.002:0.003:0.005 to obtain mixture I;

[0150] (2) Mixture I was heated to 895℃ at 5.5℃ / min under an oxygen atmosphere, held at the temperature for 8.5h, and then naturally cooled to room temperature. The mixture was then crushed by a colloid mill to obtain process product I with a D50 of 4.5μm.

[0151] (3) Process product I, lithium hydroxide, and yttrium oxide are mixed according to n(Li 0.832 Ni 0.757 Co 0.015 Mn 0.218 Zr 0.002 Al 0.003 B 0.005The mixture of O2):n(Li):n(Y) in a ratio of 1:0.208:0.002 was uniformly mixed in a high-speed mixer to obtain mixture II.

[0152] (4) Mixture II was sintered for the second time under an oxygen atmosphere by heating to 650°C at 4.5°C / min and then heating to 900°C at 2.5°C / min, holding for 8 hours, and then cooling naturally to room temperature. After crushing, process product II was obtained.

[0153] (5) Process product II is mixed with alumina and cobalt hydroxyoxide in a high-speed mixer at a mass ratio of 100:0.19:0.76 to obtain mixture III;

[0154] (6) The third sintering was carried out in air, the temperature was increased to 750℃ at 3℃ / min, held for 8h, cooled naturally to room temperature, and the obtained product was crushed to obtain process product III;

[0155] (7) Process product III is mixed with alumina, tungsten oxide and titanium oxide in a mass ratio of 100:0.28:0.25:0.30 in a high-speed mixer to obtain mixture IV;

[0156] (8) A fourth sintering process was performed in air, with the temperature increased to 410℃ at a rate of 3℃ / min, held for 8 hours, and then naturally cooled to room temperature. The resulting product was crushed and passed through a 400-mesh sieve to obtain a low-cobalt layered cathode material A5, whose composition is Li. 1.04 Ni 0.740 Co 0.022 Mn 0.213 Zr 0.002 Y 0.002 B 0.005 Al 0.012 W 0.001 Ti 0.003 O2.

[0157] Example 6

[0158] (1) Lithium carbonate, nickel cobalt manganese precursor, titanium oxide, and aluminum oxide are uniformly mixed in a high-speed mixer in the ratio of n(Li):n(Ni):n(Co):n(Mn):n(Ti):n(Al)=0.78:0.745:0:0.249:0.002:0.004 to obtain mixture I;

[0159] (2) Mixture I was heated to 895℃ at 5.5℃ / min under an oxygen atmosphere, held at the temperature for 8.5h, and then naturally cooled to room temperature. The mixture was then crushed by a colloid mill to obtain process product I with a D50 of 4.5μm.

[0160] (3) Process product I, lithium hydroxide, zirconium oxide, and yttrium oxide are mixed according to n(Li 0.78 Ni0.745 Mn 0.249 Ti 0.002 Al 0.004 The mixture of O2):n(Li):n(Zr):n(Y) in a ratio of 1:0.26:0.002:0.002 was uniformly mixed in a high-speed mixer to obtain mixture II.

[0161] (4) Mixture II was sintered for the second time under an oxygen atmosphere by heating to 650°C at 4.5°C / min and then heating to 910°C at 2.5°C / min, holding for 8 hours, and then cooling naturally to room temperature. After crushing, process product II was obtained.

[0162] (5) Process product II is mixed with alumina and cobalt hydroxyoxide in a high-speed mixer at a mass ratio of 100:0.19:1.9 to obtain mixture III;

[0163] (6) The third sintering was carried out in air, the temperature was increased to 750℃ at 3℃ / min, held for 8h, cooled naturally to room temperature, and the obtained product was crushed to obtain process product III;

[0164] (7) Process product III is mixed uniformly with alumina, tungsten oxide and titanium oxide in a mass ratio of 100:0.28:0.25:0.30 in a high-speed mixer to obtain mixture IV;

[0165] (8) A fourth sintering process was performed in air, with the temperature increased to 410℃ at a rate of 3℃ / min, held for 8 hours, and then naturally cooled to room temperature. The resulting product was crushed and passed through a 400-mesh sieve to obtain a low-cobalt layered cathode material A6, whose composition is Li. 1.04 Ni 0.718 Co 0.020 Mn 0.239 Zr 0.002 Y 0.002 Al 0.013 W 0.001 Ti 0.005 O2.

[0166] Example 7

[0167] (1) Lithium carbonate, nickel cobalt manganese precursor, titanium oxide, and aluminum oxide are uniformly mixed in a high-speed mixer in the ratio of n(Li):n(Ni):n(Co):n(Mn):n(Ti):n(Al)=0.78:0.800:0.005:0.189:0.002:0.004 to obtain mixture I;

[0168] (2) Mixture I was heated to 895℃ at 5.5℃ / min under an oxygen atmosphere, held at the temperature for 8.5h, and then naturally cooled to room temperature. The mixture was then crushed by a colloid mill to obtain process product I with a D50 of 4.5μm.

[0169] (3) Process product I, lithium hydroxide, zirconium oxide, and yttrium oxide are mixed according to n(Li 0.78 Ni 0.800 Co 0.005 Mn 0.189 Ti 0.002 Al 0.004 The mixture of O2):n(Li):n(Zr):n(Y) in a ratio of 1:0.26:0.002:0.002 was uniformly mixed in a high-speed mixer to obtain mixture II.

[0170] (4) Mixture II was sintered for the second time under an oxygen atmosphere by heating to 650°C at 4.5°C / min and then heating to 900°C at 2.5°C / min, holding for 8 hours, and then cooling naturally to room temperature. After crushing, process product II was obtained.

[0171] (5) Process product II is mixed with alumina and cobalt hydroxyoxide in a high-speed mixer at a mass ratio of 100:0.19:1.42 to obtain mixture III;

[0172] (6) The third sintering was carried out in air, the temperature was increased to 750℃ at 3℃ / min, held for 8h, cooled naturally to room temperature, and the obtained product was crushed to obtain process product III;

[0173] (7) Process product III is mixed uniformly with alumina, tungsten oxide and titanium oxide in a mass ratio of 100:0.28:0.25:0.30 in a high-speed mixer to obtain mixture IV;

[0174] (8) A fourth sintering process was performed in air, with the temperature increased to 410℃ at a rate of 3℃ / min, held for 8 hours, and then naturally cooled to room temperature. The resulting product was crushed and passed through a 400-mesh sieve to obtain a low-cobalt layered cathode material A7, whose composition is Li. 1.04 Ni 0.775 Co 0.019 Mn 0.183 Zr 0.002 Y 0.002 Al 0.013 W 0.001 Ti 0.005 O2.

[0175] Example 8

[0176] The preparation method in this embodiment is basically the same as that in Example 5, except that:

[0177] (1) Replacing zirconium oxide with magnesium oxide yields a low-cobalt layered cathode material A8, whose composition is Li 1.04 Ni 0.740 Co 0.022 Mn 0.213 Mg 0.002Y 0.002 B 0.005 Al 0.012 W 0.001 Ti 0.003 O2.

[0178] Example 9

[0179] The preparation method in this embodiment is basically the same as that in Example 5, except that:

[0180] (1) Replacing zirconium oxide with silicon oxide yields a low-cobalt layered cathode material A9, whose composition is Li 1.04 Ni 0.740 Co 0.022 Mn 0.213 Si 0.002 Y 0.002 B 0.005 Al 0.012 W 0.001 Ti 0.003 O2.

[0181] Example 10

[0182] The preparation method in this embodiment is basically the same as that in Example 5, except that:

[0183] (3) Replacing yttrium oxide with tantalum oxide yields a low-cobalt layered cathode material, A10, with the following composition: Li 1.04 Ni 0.740 Co 0.022 Mn 0.213 Zr 0.002 Ta 0.002 B 0.005 Al 0.012 W 0.001 Ti 0.003 O2.

[0184] Example 11

[0185] The preparation method in this embodiment is basically the same as that in Example 5, except that:

[0186] (3) Replacing yttrium oxide with tungsten oxide yields a low-cobalt layered cathode material Al1, whose composition is Li 1.04 Ni 0.740 Co 0.022 Mn 0.213 Zr 0.002 B 0.005 Al 0.012 W 0.003 Ti 0.003 O2.

[0187] Comparative Example 1

[0188] (1) Lithium carbonate, nickel cobalt manganese precursor, zirconium oxide, and aluminum oxide are uniformly mixed in a high-speed mixer in the ratio of n(Li):n(Ni):n(Co):n(Mn):n(Zr)=1.04:0.763:0.015:0.219:0.003 to obtain mixture I;

[0189] (2) Mixture I was heated to 650°C at 4.5°C / min under an oxygen atmosphere, and then heated to 940°C at 2.5°C / min. The temperature was maintained for 8 hours and then naturally cooled to room temperature. After crushing, process product I was obtained.

[0190] (3) Process product I is mixed with alumina and cobalt hydroxyoxide in a high-speed mixer at a mass ratio of 100:0.19:0.76 to obtain mixture II;

[0191] (4) A second sintering was carried out in air, with the temperature increased to 750°C at 3°C / min, held for 8 hours, and then naturally cooled to room temperature. The resulting product was then crushed to obtain process product II.

[0192] (5) Process product II is mixed with alumina, tungsten oxide and titanium oxide in a mass ratio of 100:0.28:0.25:0.30 in a high-speed mixer to obtain mixture III;

[0193] (6) A third sintering process was carried out in air, with the temperature increased to 410℃ at a rate of 3℃ / min, held for 8 hours, and then naturally cooled to room temperature. The resulting product was crushed and passed through a 400-mesh sieve to obtain a low-cobalt layered cathode material D1, whose composition is Li. 1.04 Ni 0.747 Co 0.023 Mn 0.214 Zr 0.003 Al 0.009 W 0.001 Ti 0.003 O2, specific data parameters are shown in Table 1 and Table 2.

[0194] Comparative Example 2

[0195] (1) Following the method of Comparative Example 1, except that the lithium source used in mixture I was lithium hydroxide, and the holding temperature of the isothermal stage I during the first sintering process was T1 = 910℃, all other conditions were the same, resulting in a low-cobalt layered cathode material D2. The composition of D2 is Li... 1.04 Ni 0.747 Co 0.023 Mn 0.214 Zr 0.003 Al 0.009 W 0.001 Ti 0.003 O2, specific data parameters are shown in Table 1 and Table 2.

[0196] Comparative Example 3

[0197] (1) Lithium carbonate, lithium hydroxide, nickel cobalt manganese precursor, zirconium oxide, and aluminum oxide are uniformly mixed in a high-speed mixer in the ratio of n(Li2CO3):n(LiOH):n(Ni):n(Co):n(Mn):n(Zr)=0.26:0.52:0.763:0.015:0.219:0.003 to obtain mixture I;

[0198] (2) Mixture I was heated to 650°C at 4.5°C / min under an oxygen atmosphere, and then heated to 900°C at 2.5°C / min. The mixture was kept at this temperature for 8 hours and then allowed to cool naturally to room temperature. After crushing, process product I was obtained.

[0199] (3) Process product I is mixed with alumina and cobalt hydroxyoxide in a high-speed mixer at a mass ratio of 100:0.19:0.76 to obtain mixture II;

[0200] (4) A second sintering was carried out in air, with the temperature increased to 750°C at 3°C / min, held for 8 hours, and then naturally cooled to room temperature. The resulting product was then crushed to obtain process product II.

[0201] (5) Process product II is mixed with alumina, tungsten oxide and titanium oxide in a mass ratio of 100:0.28:0.25:0.30 in a high-speed mixer to obtain mixture III;

[0202] (6) A third sintering process was performed in air, with the temperature increased to 410℃ at a rate of 3℃ / min, held for 8 hours, and then naturally cooled to room temperature. The resulting product was crushed and passed through a 400-mesh sieve to obtain a low-cobalt layered cathode material D3, whose composition is Li. 1.04 Ni 0.747 Co 0.023 Mn 0.214 Zr 0.003 Al 0.009 W 0.001 Ti 0.003 O2, specific data parameters are shown in Table 1 and Table 2.

[0203] Comparative Example 4

[0204] (1) Following the method of Comparative Example 3, except that the ratio of lithium carbonate, lithium hydroxide, nickel-cobalt-manganese precursor, zirconium oxide, and aluminum oxide in mixture I was n(Li₂CO₃):n(LiOH):n(Ni):n(Co):n(Mn):n(Zr):n(Al):n(Y) = 0.39:0.26:0.760:0.015:0.218:0.002:0.003:0.002, and the holding temperature of the isothermal stage I during the first sintering process was T1 = 940℃, with all other parameters remaining the same, resulting in a low-cobalt layered cathode material D4. The composition of D4 is Li 1.04 Ni 0.744 Co 0.022 Mn 0.214 Zr 0.002 Y 0.002 Al 0.012 W 0.001 Ti 0.003 O2, specific data parameters are shown in Table 1 and Table 2.

[0205] Comparative Example 5

[0206] (1) Lithium carbonate, lithium hydroxide, nickel cobalt manganese precursor, zirconium oxide, and aluminum oxide are mixed uniformly in a high-speed mixer in the ratio of n(Li2CO3):n(LiOH):n(Ni):n(Co):n(Mn):n(Zr):n(Al) = 0.39:0.26:0.761:0.015:0.219:0.002:0.003 to obtain mixture I;

[0207] (2) Mixture I was heated to 895℃ at 5.5℃ / min under an oxygen atmosphere, held at the temperature for 8.5h, and then naturally cooled to room temperature. The mixture was then crushed by a colloid mill to obtain process product I with a D50 of 4.5μm.

[0208] (3) Process product I and yttrium oxide are mixed according to n(Li 1.04 Ni 0.761 Co 0.015 Mn 0.219 Zr 0.002 Al 0.003 The mixtures with a ratio of O2:n(Y) = 1:0.002 are uniformly mixed in a high-speed mixer to obtain mixture II;

[0209] (4) Mixture II was sintered for the second time under an oxygen atmosphere by heating to 650°C at 4.5°C / min and then to 940°C at 2.5°C / min, holding for 8 hours, and then naturally cooling to room temperature. After crushing, process product II was obtained.

[0210] (5) Process product II is mixed with alumina and cobalt hydroxyoxide in a high-speed mixer at a mass ratio of 100:0.19:0.76 to obtain mixture III;

[0211] (6) The third sintering was carried out in air, the temperature was increased to 750℃ at 3℃ / min, held for 8h, cooled naturally to room temperature, and the obtained product was crushed to obtain process product III;

[0212] (7) Process product III is mixed with alumina, tungsten oxide and titanium oxide in a mass ratio of 100:0.28:0.25:0.30 in a high-speed mixer to obtain mixture IV;

[0213] (8) A fourth sintering process was performed in air, with the temperature increased to 410℃ at a rate of 3℃ / min, held for 8 hours, and then naturally cooled to room temperature. The resulting product was crushed and passed through a 400-mesh sieve to obtain a low-cobalt layered cathode material D5, whose composition is Li. 1.04 Ni 0.744 Co 0.022 Mn 0.214 Zr 0.002 Y 0.002 Al 0.012 W 0.001 Ti 0.003 O2, specific data parameters are shown in Table 1 and Table 2.

[0214] SEM observations were performed on the processed products after four sintering cycles in Example 1, and the results are shown in Figure 2. As can be seen from Figure 2, processed product I is a single crystal with small grains, processed product II has grown into a single crystal with a larger grain size, and processed product III has formed a continuous coating layer on the surface of the substrate material. The cathode material A1 has formed discontinuous dot-like or island-like coatings on part of the continuous coating layer surface.

[0215] XRD tests were performed on the cathode materials prepared in Examples 1-11 and Comparative Examples 1-5, and S was calculated for each. D1 -S C1 I D1 / I C1 F C1 and F D1 The results are shown in Table 1. Figure 1 shows the XRD patterns of the cathode materials of Example 3 and Comparative Example 4.

[0216] The charging capacity, discharging capacity, first coulombic efficiency (i.e., first efficiency), 80-cycle retention rate, and 80-cycle DCR increase of lithium-ion half-cells (4.45V) prepared with the cathode materials prepared in Examples 1-11 and Comparative Examples 1-5 were tested respectively, and the results are shown in Table 2.

[0217] Charge / discharge capacity and initial coulombic efficiency test:

[0218] The electrochemical performance of CR2025 coin cells was tested using the Shenzhen Xinwei Battery Testing System. The charge / discharge current density at 0.1C was 175 mA / g. The charge / discharge voltage range was controlled between 3.0V and 4.45V. At room temperature, the coin cells were charged and discharged at 0.1C to evaluate the charge / discharge specific capacity of the cathode material. The initial coulombic efficiency % was calculated as: (initial discharge specific capacity / initial charge specific capacity) * 100%.

[0219] 80-week cycle retention test method:

[0220] In both the examples and comparative examples, the charge / discharge voltage range was controlled to be 3.0V-4.45V. At a constant temperature of 45°C, the coin cell was charged and discharged once at 0.1C, and then charged and discharged 80 times at 1C to evaluate the high-temperature cycle capacity retention rate of the cathode material.

[0221] 80-week DCR (Impedance) Amplification Test Method:

[0222] Before the battery undergoes high-temperature cycling, its impedance at 50% SOC is measured after it is fully charged; this is the initial impedance. After the battery has completed the high-temperature cycling test, its impedance at 50% SOC is measured after it is fully charged; this is the final impedance. The impedance growth rate % = (final impedance - initial impedance) / initial impedance × 100%.

[0223] Table 1

[0224] Table 2

[0225] As can be seen from Tables 1 and 2, compared with Comparative Examples 1-5, the charging capacity, discharging capacity, first-time efficiency, and 80-cycle retention rate of Examples 1-11 are significantly improved, and the 80-cycle DCR increase is significantly reduced. The 80-cycle high-temperature cycle capacity retention rate of Examples 1-11 of this disclosure is all above 89%, and the DCR increase is all below 160%, while the 80-cycle high-temperature cycle capacity retention rate of Comparative Examples 1-5 is all below 86%, and the DCR increase is all above 220%. It is evident that by limiting 0.80 ≤ I... D1 / I C1 ≤1.00, 0.80≤A D1 / A C1 ≤1.05, 0.35°≤S D1 -S C1 ≤0.65°, 1.77≤Ic1 / I C2 ≤1.98, 1.78≤I D1 / I D2 ≤2.19、0°<F C1 ≤0.20° and 0°<FD1 A value ≤0.20° can effectively improve the initial charge / discharge efficiency, discharge capacity, and cycle performance of the battery, while effectively reducing the initial impedance and impedance increase. Furthermore, comparing Examples 1-11 shows that, compared to Examples 1, 4, 10, and 11, Examples 3 and Examples 5-7 further improve the charging capacity, discharging capacity, initial efficiency, and 80-cycle retention rate, and further reduce the 80-cycle DCR increase. Example 7, in particular, exhibits the best overall performance. This demonstrates that limiting the initial charge / discharge efficiency to ≤0.20° can effectively improve the battery's initial charge / discharge efficiency, discharge capacity, and cycle performance, while also effectively reducing the initial impedance and impedance increase. D1 / I C1 ≤0.95, 0.85≤A D1 / A C1 ≤1.00, 0.40°≤S D1 -S C1 ≤0.60°, 1.80≤Ic1 / I C2 ≤1.95, 1.80≤I D1 / I D2 ≤2.00, 0.05°≤F C1 ≤0.15° and 0.05°≤F D1 With a tolerance of ≤0.15°, the initial charge and discharge efficiency, discharge capacity, and cycle performance of the battery can be further improved, while the initial impedance and impedance increase of the battery can be further reduced.

[0226] Figure 3 is a schematic diagram of the cycle retention rate of batteries made from low-cobalt layered cathode materials in Examples 1, 3, 4, 7 and Comparative Example 1. The horizontal axis represents the number of cycles and the vertical axis represents the capacity retention rate. The cycle life of the batteries was tested at 45 degrees Celsius at a charge-discharge rate of 1C within a voltage range of 3.0V to 4.45V.

[0227] As can be seen from Figure 3, compared with Comparative Example 1, the cycle retention rates of Examples 1, 3, 4, and 7 are significantly improved. This shows that by limiting the value to 0.80 ≤ I... D1 / I C1 ≤1.00, 0.80≤A D1 / A C1 ≤1.05, 0.35°≤S D1 -S C1 ≤0.65°, 1.77≤Ic1 / I C2 ≤1.98, 1.78≤I D1 / I D2 ≤2.19、0°<F C1 ≤0.20° and 0°<F D1 ≤0.20° can effectively improve the cycle performance of the battery.

[0228] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0229] Although embodiments of the present disclosure have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A positive electrode active material, wherein, In the XRD pattern of the positive electrode active material, the characteristic peak C(018) corresponding to the (018) crystal plane of the positive electrode active material exhibits a bimodal distribution, including a first characteristic peak C located on the small-angle side. 1 (018) and the second characteristic peak C on the large angle side 2 (018); The characteristic peak D(110) corresponding to the (110) crystal plane of the positive electrode active material exhibits a bimodal distribution, including the first characteristic peak D located on the small angle side. 1 (110) and the second characteristic peak D on the large angle side 2 (110); I C1 The first characteristic peak C corresponding to the (018) crystal plane of the positive electrode active material is indicated by... 1 The strength of (018), I D1 The first characteristic peak D corresponding to the (110) crystal plane of the positive electrode active material is represented by... 1 The strength of (110) satisfies 0.80 ≤ I D1 / I C1 ≤1.

00.

2. The positive electrode active material according to claim 1, wherein, I C1 Japanese I D1 full foot 0.85≤I D1 / I C1 ≤0.

95.

3. The positive electrode active material according to claim 1 or 2, wherein, A C1 The first characteristic peak C corresponding to the (018) crystal plane of the positive electrode active material is indicated by... 1 The peak area of ​​(018), A D1 The first characteristic peak D corresponding to the (110) crystal plane of the positive electrode active material is represented by... 1 The peak area of ​​(110) satisfies 0.80 ≤ A D1 / A C1 ≤1.

05.

4. The positive electrode active material according to claim 3, wherein, Satisfying 0.85≤A D1 / A C1 ≤1.

00.

5. The positive electrode active material according to any one of claims 1 to 4, wherein, S C1 The first characteristic peak C corresponding to the (018) crystal plane of the positive electrode active material is indicated by... 1 The position of (018), S D1 The first characteristic peak D corresponding to the (110) crystal plane of the positive electrode active material is represented by... 1 The position of (110) satisfies 0.35°≤S D1 -S C1 ≤0.65°.

6. The positive electrode active material according to claim 5, wherein, Satisfying 0.40°≤S D1 -S C1 ≤0.60°.

7. The positive electrode active material according to any one of claims 1 to 6, wherein, I C2 The second characteristic peak C corresponding to the (018) crystal plane of the positive electrode active material is indicated. 2 The strength of (018), I D2 The second characteristic peak D corresponding to the (110) crystal plane of the positive electrode active material is represented by... 2 The strength of (110) satisfies 1.77≤Ic1 / I C2 ≤1.98, 1.78≤I D1 / I D2 ≤2.

19.

8. The positive electrode active material according to claim 7, wherein, 1.80≤Ic1 / I C2 ≤1.95, 1.80≤I D1 / I D2 ≤2.

00.

9. The positive electrode active material according to any one of claims 1 to 8, wherein, F C1 The first characteristic peak C corresponding to the (018) crystal plane of the positive electrode active material is indicated by... 1 The half-width of (018), F D1 The first characteristic peak D corresponding to the (110) crystal plane of the positive electrode active material is represented by... 1 The half-width of (110) satisfies 0° < F C1 ≤0.20°, 0°<F D1 ≤0.20°.

10. The positive electrode active material according to claim 9, wherein, Satisfying 0.05°≤F C1 ≤0.15°, 0.05°≤F D1 ≤0.15°.

11. The positive electrode active material according to any one of claims 1 to 10, wherein, The chemical formula of the positive electrode active material is Li a (Ni x Co y Mn z M b R c O2, wherein 0.95≤a≤1.10, 0.50≤x≤0.95, 0≤y≤0.05, 0≤z≤0.45, 0≤b≤0.05, 0≤c≤0.03, and at least one of b and c is not equal to 0; M and R are independently selected from at least one of B, Mg, Sr, Ba, Fe, Cu, Ni, Co, Mn, Sc, Y, La, Ce, Sm, Eu, Gd, Tb, Dy, Yb, Lu, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ru, Rh, Ir, Zn, Al, Ga, In, Si, Pb, Cd, Ge, Sn, Sb, Bi, and Te.

12. The positive electrode active material according to any one of claims 1 to 11, wherein, The positive electrode active material includes a matrix material and a coating layer, wherein the coating layer is disposed on at least a portion of the surface of the matrix material.

13. The positive electrode active material according to claim 12, wherein, The coating layer includes a continuous coating layer and a coating material protruding from the surface of the continuous coating layer, wherein the coating material includes at least one of dot-shaped coating material and island-shaped coating material.

14. The positive electrode active material according to claim 13, wherein, The continuous coating layer includes at least one of lithium cobalt oxide of Al, lithium cobalt oxide of W, lithium cobalt oxide of Zr, and lithium cobalt oxide of B. And / or, the coating comprises at least one of aluminum oxide, tungsten oxide, titanium oxide, boron oxide, strontium oxide, lithium oxide of Al, lithium oxide of W, lithium oxide of Ti, lithium oxide of B, and lithium oxide of Sr.

15. A method for preparing the positive electrode active material according to any one of claims 1 to 14, wherein, include: The nickel-cobalt-manganese precursor, the first lithium source, and the first doping additive are mixed according to the stoichiometric ratio and subjected to the first sintering to obtain the first sintered product. The first sintered product, the second lithium source, and the optional second doping additive are mixed according to the stoichiometric ratio and then sintered a second time to obtain the second sintered product. The second sintered product and the coating agent are mixed and sintered a third time to obtain the positive electrode active material.

16. The method according to claim 15, wherein, The first sintering includes a first heating stage and a first isothermal stage. The heating rate of the first heating stage is 1℃ / min to 15℃ / min, the temperature of the first isothermal stage is 600℃ to 1000℃, and the duration of the first isothermal stage is 2h to 20h. And / or, the second sintering includes a second heating stage, a third heating stage, and a second isothermal stage, wherein the heating rate of the second heating stage is greater than the heating rate of the third heating stage, and the difference between the heating rates of the second heating stage and the third heating stage is 1℃ / min to 5℃ / min, the temperature of the second isothermal stage is 600℃ to 1200℃, and the duration of the second isothermal stage is 2h to 24h.

17. The method according to claim 15 or 16, wherein, The first doping additive is selected from at least one of oxides and hydroxides containing doping element M; And / or, the second doping additive is selected from at least one of oxides and hydroxides containing doping element R; And / or, the first lithium source includes lithium carbonate, the second lithium source includes lithium hydroxide, and the molar ratio of the first lithium source to the second lithium source is (30-90):(10-70).

18. The method according to any one of claims 15 to 17, wherein, The process of mixing the second sintered product and the coating agent and then performing a third sintering includes the following steps: The second sintered product and the first coating agent are mixed and sintered a third time to obtain the third sintered product. The third sintering product and the second coating agent are mixed and sintered a fourth time to obtain the positive electrode active material.

19. The method according to claim 18, wherein, The third sintering includes a fourth heating stage and a third isothermal stage. The heating rate of the fourth heating stage is 1℃ / min to 15℃ / min, the temperature of the third isothermal stage is 500℃ to 1000℃, and the duration of the third isothermal stage is 2h to 20h. And / or, the fourth sintering includes a fifth heating stage and a fourth isothermal stage, wherein the heating rate of the fifth heating stage is 1℃ / min to 15℃ / min, the temperature of the fourth isothermal stage is 200℃ to 800℃, and the duration of the fourth isothermal stage is 2h to 20h. And / or, the first coating agent is selected from at least one of oxides, hydroxides, and carbonates containing Al, W, Zr, or B; And / or, the second coating agent is selected from at least one of oxides, hydroxides, and carbonates containing Al, W, Ti, B, or Sr; And / or, the mass of the first coating agent is 0.01% to 2% of the mass of the second sintered product; And / or, the mass of the second coating agent is 0.01% to 2% of the mass of the third sintered product.

20. A positive electrode plate, wherein, It includes the positive electrode active material according to any one of claims 1 to 14 or the positive electrode active material prepared by the method according to any one of claims 15 to 19.

21. A battery, wherein, Includes the positive electrode sheet as described in claim 20.

22. An electrical appliance, wherein, Includes the battery as described in claim 21.

Images