Lithium cobalt oxide composite material, preparation method thereof, electrode plate and battery

Abstract

The invention relates to a lithium cobalt oxide composite material and a preparation method thereof, an electrode plate and a battery. The lithium cobalt oxide composite material comprises a lithium cobalt oxide core and a shell coating at least part of the surface of the lithium cobalt oxide core, and the lithium cobalt oxide core comprises first lithium cobalt oxide and second lithium cobalt oxide; the median particle size of the first lithium cobalt oxide is d1, the median particle size of the second lithium cobalt oxide is d2, the median particle size of a precursor first cobalt source of the first lithium cobalt oxide is d3, and d3 is larger than or equal to 3 microns and smaller than or equal to 5 microns; the median particle size of a second cobalt source of a precursor of second lithium cobalt oxide is d4, and d4 is more than or equal to 3 microns and less than or equal to 5 microns; wherein d1-d3 is more than or equal to 10 microns and less than or equal to 17 microns; 0 [mu] m < = d2-d4 < = 3 [mu] m. According to the preparation method, the compaction density of the lithium cobalt oxide composite material can be effectively improved, so that the specific capacity and the cycle performance of the lithium ion battery are improved.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and particularly to a lithium cobalt oxide composite material, a preparation method thereof, an electrode sheet, and a battery. Background Art

[0002] In the current battery market, the requirements for the volumetric energy density of lithium-ion batteries continue to rise. Improving the tap density of the cathode material of lithium-ion batteries is one of the main directions for improving the volumetric energy density of lithium-ion batteries. However, the tap density of traditional cathode materials needs to be further improved. Summary of the Invention

[0003] Based on this, the present application provides a lithium cobalt oxide composite material with a relatively high tap density, a preparation method thereof, an electrode sheet, a battery, and an electrical device.

[0004] The technical solution of the present application to solve the above technical problems is as follows.

[0005] In a first aspect of the present application, a lithium cobalt oxide composite material is provided, which includes a lithium cobalt oxide core and a shell coated on at least a part of the surface of the lithium cobalt oxide core. The lithium cobalt oxide core includes a first lithium cobalt oxide and a second lithium cobalt oxide;

[0006] The median particle size of the first lithium cobalt oxide is d1, the median particle size of the second lithium cobalt oxide is d2, the median particle size of the first cobalt source, which is the precursor of the first lithium cobalt oxide, is d3, and 3μm ≤ d3 ≤ 5μm; the median particle size of the second cobalt source, which is the precursor of the second lithium cobalt oxide, is d4, and 3μm ≤ d4 ≤ 5μm;

[0007] Wherein, 10μm ≤ d1 - d3 ≤ 17μm; 0μm ≤ d2 - d4 ≤ 3μm.

[0008] In some embodiments, in the lithium cobalt oxide composite material, 15μm ≤ d1 ≤ 20μm;

[0009] And / or, 3μm ≤ d2 ≤ 6μm;

[0010] And / or, the particle size distribution width of the first lithium cobalt oxide is 1.0 - 1.5;

[0011] And / or, the mass ratio of the first lithium cobalt oxide to the second lithium cobalt oxide is 3 - 5:1.

[0012] In some embodiments, in the lithium cobalt oxide composite material, the median particle size of the lithium cobalt oxide composite material is 13μm - 18μm;

[0013] And / or, the particle size distribution width of the lithium cobalt oxide composite material is 1.5 - 1.8;

[0014] And / or, the powder compaction density of the lithium cobaltate composite material is ≥ 4.1 g / cm³ under 200 MPa 3 ;

[0015] And / or, the ultimate compaction density of the electrode sheet of the lithium cobaltate composite material is ≥ 4.2 g / cm³ 3 .

[0016] In some embodiments, in the lithium cobaltate composite material, the chemical formula of the lithium cobaltate composite material is Li u Co v M x Q y R γ O₂E z ; where 1.00 < u ≤ 1.07, 0.95 < v ≤ 1, 0 ≤ x < 1, 0 ≤ y < 1, 0 ≤ γ < 0.1, 0 ≤ z < 0.1, M includes at least one of magnesium, tungsten, titanium, yttrium, aluminum, nickel, manganese, lanthanum, niobium, vanadium, molybdenum, and zirconium elements, E includes at least one of fluorine, chlorine, and sulfur elements, Q includes at least one of aluminum, magnesium, nickel, manganese, titanium, yttrium, lanthanum, and zirconium, and R includes at least one of magnesium, tungsten, titanium, yttrium, aluminum, nickel, manganese, lanthanum, vanadium, molybdenum, strontium, germanium, niobium, indium, zirconium, and halogen elements.

[0017] The second aspect of the present application provides a preparation method of a lithium cobaltate composite material, including the following steps:

[0018] After mixing the first cobalt source and the first lithium source, first sintering and crushing are carried out in sequence to prepare the first lithium cobaltate. The median particle size of the first lithium cobaltate is d1, the median particle size of the first cobalt source is d3, 3μm ≤ d3 ≤ 5μm, and 10μm ≤ d1 - d3 ≤ 17μm;

[0019] After mixing the second cobalt source and the second lithium source, second sintering and crushing are carried out in sequence to prepare the second lithium cobaltate. The median particle size of the second lithium cobaltate is d2, the median particle size of the second cobalt source is d4, 3μm ≤ d4 ≤ 5μm, and 0μm ≤ d2 - d4 ≤ 3μm;

[0020] After mixing the first lithium cobaltate and the second lithium cobaltate, third sintering and crushing are carried out in sequence to prepare the lithium cobaltate composite material.

[0021] In some embodiments, in the preparation method of the lithium cobaltate composite material, the first sintering includes the following steps:

[0022] Heat up at a rate of 3°C / min to 8°C / min to 600°C to 800°C, and keep warm for 2 h to 4 h; then heat up at a rate of 1°C / min to 3°C / min to 1050°C to 1100°C, and keep warm for 5 h to 10 h;

[0023] And / or, the second sintering includes the following steps:

[0024] Heat up to 600°C - 800°C at a rate of 3°C / min - 8°C / min, hold for 2 - 4 h, then heat up to 980°C - 1015°C at a rate of 1°C / min - 3°C / min, and hold for 5 - 10 h;

[0025] And / or, the third sintering includes the following steps:

[0026] Heat up to 700°C - 900°C at a rate of 3°C / min - 8°C / min, and hold for 5 h - 10 h.

[0027] In some embodiments, in the preparation method of the lithium cobalt oxide composite material, the first cobalt source and the second cobalt source each independently include at least one of cobalt tetroxide, cobalt hydroxide, cobaltous oxide, cobalt nitrate, cobalt carbonate, cobalt oxalate, and cobalt oxyhydroxide;

[0028] And / or, the first lithium source and the second lithium source each independently include at least one of lithium carbonate, lithium nitrate, lithium acetate, lithium hydroxide, and lithium fluoride;

[0029] And / or, the molar ratio of the first lithium source to the first cobalt source is 1.05 - 1.08:1;

[0030] And / or, the molar ratio of the second lithium source to the second cobalt source is 1.05 - 1.08:1.

[0031] In some embodiments, in the preparation method of the lithium cobalt oxide composite material, the preparation method satisfies at least one of the following characteristics:

[0032] (1) The first cobalt source and the second cobalt source each independently contain a doping element Q; optionally, the doping element Q includes at least one of aluminum, magnesium, nickel, manganese, titanium, yttrium, lanthanum, and zirconium; optionally, the doping amount of the doping element Q is 3000 ppm - 15000 ppm;

[0033] (2) In the step of mixing the first cobalt source and the first lithium source, a step of adding a first dopant is further included; and / or, in the step of mixing the second cobalt source and the second lithium source, a step of adding a second dopant is further included; optionally, the first dopant and the second dopant each independently include at least one of a doping element M and a doping element E, the doping element M is selected from at least one of magnesium, tungsten, titanium, yttrium, aluminum, nickel, manganese, lanthanum, niobium, vanadium, molybdenum, and zirconium, and the doping element E is selected from at least one of fluorine, chlorine, and sulfur elements;

[0034] (3) In the step of mixing the first lithium cobaltate and the second lithium cobaltate, a step of adding a coating agent is further included; optionally, the coating agent includes a third cobalt source and a third dopant, the third cobalt source includes at least one of cobalt tetroxide, cobalt hydroxide, cobaltous oxide, cobalt nitrate, nano-cobalt carbonate, and cobalt oxyhydroxide, the third dopant includes a doping element R, and the doping element R is selected from at least one of magnesium, tungsten, titanium, yttrium, aluminum, nickel, manganese, lanthanum, vanadium, molybdenum, strontium, germanium, niobium, indium, zirconium, and halogen elements; and / or, the mass of the third cobalt source is 0.25% to 0.75% of the total mass of the first lithium cobaltate and the second lithium cobaltate; and / or, the mass of the third dopant is 500 ppm to 8000 ppm of the total mass of the first lithium cobaltate and the second lithium cobaltate.

[0035] The third aspect of the present application provides an electrode pole piece, including the lithium cobaltate composite material provided in the first aspect or the lithium cobaltate composite material prepared by the preparation method of the lithium cobaltate composite material provided in the second aspect.

[0036] The fourth aspect of the present application provides a battery, including the electrode pole piece provided in the third aspect.

[0037] Beneficial effects:

[0038] The lithium cobaltate composite material of the present application includes a lithium cobaltate core and a shell coated on at least a part of the surface of the lithium cobaltate core. The lithium cobaltate core includes a first lithium cobaltate and a second lithium cobaltate; by controlling the median particle size of the first cobalt source, which is the precursor of the first lithium cobaltate, and controlling the difference between the median particle size of the first cobalt source and the median particle size of the first lithium cobaltate, a first lithium cobaltate with a larger particle size is obtained using a first cobalt source with a smaller particle size, which can make the particle size distribution of the first lithium cobaltate wider and the particle size distance larger; combining the first lithium cobaltate with a wider particle size distribution and a larger particle size with the second lithium cobaltate with a smaller particle size can effectively improve the particle size distribution width of the lithium cobaltate composite material, thereby effectively improving the tap density of the lithium cobaltate composite material, laying a good foundation for subsequent improvement of the specific capacity and cycle performance of the lithium-ion battery. Description of the drawings

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application and more completely understand the present application and its beneficial effects, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative efforts.

[0040] Figure 1 It is a particle size distribution diagram of the lithium cobaltate composite material prepared in step (3) of Example 1 and Comparative Example 1;

[0041] Figure 2 It is the particle size distribution diagram of the first lithium cobaltate material prepared in step (1) of Example 1 and Comparative Example 1;

[0042] Figure 3 It is the particle size distribution diagram of the second lithium cobaltate material prepared in step (2) of Example 1;

[0043] Figure 4 It is the particle size distribution diagram of the first cobalt source Co3O4 used in step (1) of Example 1;

[0044] Figure 5 It is the particle size distribution diagram of the first cobalt source Co3O4 used in step (1) of Comparative Example 1. Specific embodiments

[0045] The present application will be further described in detail below in combination with embodiments and examples. It should be understood that these embodiments and examples are only used to illustrate the present application and not to limit the scope of the present application. The purpose of providing these embodiments and examples is to make the understanding of the disclosed content of the present application more thorough and comprehensive.

[0046] It should also be understood that the present application can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various changes or modifications without departing from the connotation of the present application, and the equivalent forms obtained also fall within the protection scope of the present application. For example, the features described or illustrated as part of one embodiment can be combined in a suitable manner with another embodiment to produce a new embodiment. In addition, in the following description, a large number of specific details are given to provide a more thorough understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing the embodiments and examples and are not intended to limit the present application.

[0048] Unless otherwise stated or there is a contradiction, the terms or phrases used herein have the following meanings:

[0049] In this application, references to "a plurality of", "a variety of", "multiple times", etc., unless otherwise specified, mean greater than 2 or equal to 2 in quantity. For example, "one or more" means one or greater than or equal to two.

[0050] The "combinations thereof", "any combinations thereof", "any combination manners thereof", etc. used herein include all suitable combination manners of any two or more of the listed items.

[0051] In this application, the "suitable combination method", "suitable method", "any suitable method", etc., the "suitable" described therein shall be subject to being able to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0052] In this application, "preferred", "better", "more preferable", "it is advisable" are only used to describe the implementation manners or embodiments with better effects. It should be understood that they do not constitute a limitation on the protection scope of this application. If there are multiple "preferred" in a technical solution, without special instructions and without contradictions or mutual restrictions, each "preferred" is independent of each other.

[0053] In this application, "further", "furthermore", "especially", etc. are used for descriptive purposes, indicating differences in content, but should not be understood as a limitation on the protection scope of this application.

[0054] In this application, "optionally", "optional", "option" mean that it can be there or not, that is, it refers to any one selected from two parallel options of "having" or "not having". If there are multiple "optional" in a technical solution, without special instructions and without contradictions or mutual restrictions, each "optional" is independent of each other.

[0055] In this application, in "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc., the terms "first", "second", "third", "fourth", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or quantity, nor can it be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive list description, and it should be understood that they do not constitute a closed limitation on quantity.

[0056] In this application, for the technical features described in an open manner, it includes the closed technical solutions composed of the listed features, and also includes the open technical solutions containing the listed features.

[0057] In this application, when it comes to numerical intervals (i.e., numerical ranges), unless otherwise specified, the distribution of the selectable numerical values within the numerical interval is considered continuous, and includes the two numerical endpoints of the numerical interval (i.e., the minimum value and the maximum value), as well as each numerical value between these two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers within the numerical interval, it includes the two endpoint integers of the numerical range, as well as each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. The "numerical interval" is allowed to broadly include numerical interval types such as percentage intervals, ratio intervals, ratio value intervals, etc.

[0058] The temperature parameter in this application, unless otherwise specified, allows both constant temperature treatment and variation within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, ±1°C are allowed.

[0059] In this application, the term "room temperature" or "normal temperature" generally refers to 4°C to 35°C, such as 20°C ± 5°C. In some embodiments of this application, "room temperature" or "normal temperature" refers to 10°C to 30°C. In some embodiments of this application, "room temperature" or "normal temperature" refers to 20°C to 30°C.

[0060] In this application, regarding the unit of the data range, if the unit is only attached after the right endpoint, it means that the units of the left endpoint and the right endpoint are the same. For example, 3~5 h means that the units of the left endpoint "3" and the right endpoint "5" are both h (hours).

[0061] All the documents mentioned in this application are cited as references in this application, just as if each document is cited separately as a reference. Unless it conflicts with the invention purpose and / or technical solution of this application, the cited documents related to this application are cited for all their contents and all their purposes. When this application involves cited documents, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited together. When this application involves cited documents, the examples and preferred ways of the relevant technical features cited can also be incorporated as references into this application, but only to the extent that this application can be implemented. It should be understood that when the cited content conflicts with the description in this application, this application shall prevail or be amended adaptively according to the description in this application.

[0062] In the description of the embodiments of the present application, the mass or weight of the relevant components not only refers to the specific content of each component, but also represents the proportional relationship of the mass or weight between each component. Therefore, as long as the content of the relevant components in the description of the embodiments of the present application is enlarged or reduced in proportion, it is within the scope disclosed in the description of the embodiments of the present application. Specifically, the mass or weight described in the description of the embodiments of the present application can be units well-known in the chemical industry such as μg, mg, g, kg, etc.

[0063] The median particle size refers to the particle size corresponding to when the cumulative particle size distribution percentage reaches 50% in the particle size distribution, and is also called the median particle size or D50 particle size.

[0064] An embodiment of the present application provides a lithium cobalt oxide composite material, including a lithium cobalt oxide core and a shell coated on at least a part of the surface of the lithium cobalt oxide core, and the lithium cobalt oxide core includes a first lithium cobalt oxide and a second lithium cobalt oxide;

[0065] The median particle size of the first lithium cobalt oxide is d1, the median particle size of the second lithium cobalt oxide is d2, the median particle size of the first cobalt source, which is the precursor of the first lithium cobalt oxide, is d3, and 3μm ≤ d3 ≤ 5μm; the median particle size of the second cobalt source, which is the precursor of the second lithium cobalt oxide, is d4, and 3μm ≤ d4 ≤ 5μm;

[0066] Wherein, 10μm ≤ d1 - d3 ≤ 17μm; 0μm ≤ d2 - d4 ≤ 3μm.

[0067] By controlling the median particle size of the first cobalt source, which is the precursor of the first lithium cobalt oxide, and controlling the difference between the median particle size of the first cobalt source and the median particle size of the first lithium cobalt oxide, a first lithium cobalt oxide with a larger particle size is obtained using the first cobalt source with a smaller particle size as the precursor, which can make the particle size distribution of the first lithium cobalt oxide wider and the particle size distance larger; matching the first lithium cobalt oxide with a wider particle size distribution and a larger particle size with the second lithium cobalt oxide with a smaller particle size can effectively improve the particle size distribution width of the lithium cobalt oxide composite material, thereby effectively improving the tap density of the lithium cobalt oxide composite material, laying a good foundation for subsequent improvement of the specific capacity and cycle performance of the lithium-ion battery.

[0068] During the compaction process of the lithium cobalt oxide composite material with a wide particle size distribution, medium and small particles can fill the voids between large and medium particles, increasing the density and compactness of the lithium cobalt oxide composite material; this filling effect can reduce the voids inside the material and achieve the purpose of improving the tap density of the material.

[0069] It can be further understood that the median particle size of the first cobalt source d3 includes but is not limited to 3μm, 3.2μm, 3.5μm, 3.8μm, 4μm, 4.2μm, 4.5μm, 4.8μm, 5μm; the median particle size of the second cobalt source d4 includes but is not limited to 3μm, 3.2μm, 3.5μm, 3.8μm, 4μm, 4.2μm, 4.5μm, 4.8μm, 5μm; in some examples, it can be within the range formed by any two of these point values as the end values, and the same applies hereinafter.

[0070] It can also be understood that "d1 - d3" refers to the difference between the median particle size of the first lithium cobaltate and the median particle size of the first cobalt source; "d2 - d4" refers to the difference between the median particle size of the second lithium cobaltate and the median particle size of the second cobalt source; further, the difference of d1 - d3 includes but is not limited to 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm; the difference of d2 - d4 includes but is not limited to 0μm, 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm.

[0071] It can be understood that the median particle size of the first cobalt source and the median particle size of the second cobalt source can be the same or different, and the two sizes are close.

[0072] In some of these examples, in the lithium cobaltate composite material, the median particle size of the lithium cobaltate composite material is 13μm to 18μm.

[0073] It can be understood that the median particle size of the lithium cobaltate composite material includes but is not limited to 13μm, 14μm, 15μm, 16μm, 17μm, 18μm.

[0074] In some of these examples, in the lithium cobaltate composite material, the particle size range of the lithium cobaltate composite material is 1.5 to 1.8.

[0075] Particle size range = (D90 - D10) / D50, where D90 refers to the particle size value corresponding to the cumulative distribution percentage reaching 90% from small to large in the particle size distribution, that is, 90% of the particles in the sample are smaller than this particle size, and it represents the upper limit of large particles; D10 refers to the particle size value corresponding to the cumulative distribution percentage reaching 10% from small to large in the particle size distribution, that is, 10% of the particles in the sample are smaller than this particle size.

[0076] In some of these examples, in the lithium cobaltate composite material, 15μm ≤ d1 ≤ 20μm (the median particle size d1 of the first lithium cobaltate is 15 μm to 20 μm). It can be understood that the median particle size d1 of the first lithium cobaltate includes but is not limited to 15μm, 16μm, 17μm, 18μm, 19μm, 20μm.

[0077] In some of these examples, in the lithium cobalt oxide composite material, the radial distance of the first lithium cobalt oxide is 1 to 1.5.

[0078] In some of these examples, in the lithium cobalt oxide composite material, 3 μm ≤ d2 ≤ 6 μm (the median particle size d2 of the second lithium cobalt oxide is 3 μm to 6 μm).

[0079] It can be understood that the median particle size d2 of the second lithium cobalt oxide includes but is not limited to 3 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm, 4.8 μm, 5 μm, 5.2 μm, 5.5 μm, 5.8 μm, 6 μm.

[0080] In some of these examples, in the lithium cobalt oxide composite material, the mass ratio of the first lithium cobalt oxide to the second lithium cobalt oxide is 3 to 5:1.

[0081] It can be understood that the mass ratio of the first lithium cobalt oxide to the second lithium cobalt oxide includes but is not limited to 3:1, 3.2:1, 3.5:1, 3.8:1, 4:1, 4.2:1, 4.5:1, 4.8:1, 5:1.

[0082] In some of these examples, in the lithium cobalt oxide composite material, the chemical formula of the lithium cobalt oxide composite material is Li u Co v M x Q y R γ O2E z ; where 1.00 < u ≤ 1.07, 0.95 < v ≤ 1, 0 ≤ x < 1, 0 ≤ y < 1, 0 ≤ γ < 0.1, 0 ≤ z < 0.1, M includes at least one of the elements magnesium, tungsten, titanium, yttrium, aluminum, nickel, manganese, lanthanum, niobium, vanadium, molybdenum, and zirconium, E includes at least one of the elements fluorine, chlorine, and sulfur, Q includes at least one of aluminum, magnesium, nickel, manganese, titanium, yttrium, lanthanum, and zirconium, and R includes at least one of magnesium, tungsten, titanium, yttrium, aluminum, nickel, manganese, lanthanum, vanadium, molybdenum, strontium, germanium, niobium, indium, zirconium, and halogen elements.

[0083] It can be understood that M and E are doping elements in the doping agent added during the mixed sintering of the first cobalt source and the first lithium source, and / or during the mixed sintering of the second cobalt source and the second lithium source, Q is a doping element in at least one of the first cobalt source and the second cobalt source, and R is a doping element in the outer shell.

[0084] In some of these examples, in the lithium cobalt oxide composite material, the chemical formula of the first lithium cobalt oxide is Li u1 Co v1 M x1 Q y1 O2E z1; wherein, 1.01 < u1 ≤ 1.08, 0.95 < v1 ≤ 1, 0 ≤ x1 < 1, 0 ≤ y1 < 1, 0 ≤ z1 < 0.1, M comprises at least one of the elements magnesium, tungsten, titanium, yttrium, aluminum, nickel, manganese, lanthanum, niobium, vanadium, molybdenum and zirconium, E comprises at least one of the elements fluorine, chlorine and sulfur, and Q comprises at least one of aluminum, magnesium, nickel, manganese, titanium, yttrium, lanthanum and zirconium.

[0085] In some of these examples, in the lithium cobalt oxide composite material, the chemical formula of the second lithium cobalt oxide is Li u2 Co v2 M ， x2 Q ， y2 O2E ， z2 ; wherein, 1.01 < u2 ≤ 1.07, 0.95 < v2 ≤ 1, 0 ≤ x2 < 1, 0 ≤ y2 < 1, 0 ≤ z2 < 0.1, M ， comprises at least one of the elements magnesium, tungsten, titanium, yttrium, aluminum, nickel, manganese, lanthanum, niobium, vanadium, molybdenum and zirconium, E ， comprises at least one of the elements fluorine, chlorine and sulfur, Q ， comprises at least one of aluminum, magnesium, nickel, manganese, titanium, yttrium, lanthanum and zirconium.

[0086] In some of these examples, in the lithium cobalt oxide composite material, the powder compaction density of the lithium cobalt oxide composite material at 200 MPa ≥ 4.1 g / cm 3 . Optionally, the powder compaction density of the lithium cobalt oxide composite material at 200 MPa is 4.1 g / cm 3 ~4.2 g / cm 3 .

[0087] In some of these examples, in the lithium cobalt oxide composite material, the ultimate compaction density of the lithium cobalt oxide composite material ≥ 4.2 g / cm 3 . Optionally, the ultimate compaction density of the lithium cobalt oxide composite material is 4.28 g / cm 3 ~4.35 g / cm 3 .

[0088] In some of these examples, in the lithium cobalt oxide composite material, the specific surface area of the lithium cobalt oxide composite material is 0.19 m 2 / g ~ 0.24 m 2 / g.

[0089] In some of these examples, in the lithium cobalt oxide composite material, the tapped density of the lithium cobalt oxide composite material is 2.8 g / cm 3 ~3.2 g / cm 3 .

[0090] One embodiment of the present application provides a method for preparing a lithium cobalt oxide composite material, comprising the following steps:

[0091] Step S10: After mixing a first cobalt source and a first lithium source, perform first sintering and crushing in sequence to prepare a first lithium cobalt oxide; the median particle size of the first lithium cobalt oxide is d1, the median particle size of the first cobalt source is d3, 3μm ≤ d3 ≤ 5μm, 10μm ≤ d1 - d3 ≤ 17μm;

[0092] Step S20: After mixing a second cobalt source and a second lithium source, perform second sintering and crushing in sequence to prepare a second lithium cobalt oxide; the median particle size of the second lithium cobalt oxide is d2, the median particle size of the second cobalt source is d4, 3μm ≤ d4 ≤ 5μm, 0μm ≤ d2 - d4 ≤ 3μm;

[0093] Step S30: After mixing the first lithium cobalt oxide and the second lithium cobalt oxide, perform third sintering and crushing in sequence to prepare a lithium cobalt oxide composite material.

[0094] By using a first cobalt source with a smaller particle size as a raw material, sintering it into a first lithium cobalt oxide with a larger particle size, and controlling the particle size difference between the first lithium cobalt oxide and the first cobalt source within a suitable range, the particle size distribution of the first lithium cobalt oxide can be made wider and the particle size distance can be made larger; sintering the first lithium cobalt oxide with a wider particle size distribution and a larger particle size together with the second lithium cobalt oxide with a smaller particle size can promote the formation of a lithium cobalt oxide composite material with a wider particle size distribution, thereby effectively improving the tap density of the lithium cobalt oxide composite material.

[0095] It is found through research that if a first cobalt source with a larger particle size is used as a raw material, the particle size difference between the sintered first lithium cobalt oxide and the first cobalt source is smaller (d2 - d1 < 10μm, for example, d2 - d1 = 2.2μm), which limits the particle size distribution of the first lithium cobalt oxide. Further, the particle size distribution of the lithium cobalt oxide composite material obtained by sintering with the second lithium cobalt oxide is limited, resulting in a smaller tap density of the lithium cobalt oxide composite material.

[0096] The method for preparing a lithium cobalt oxide composite material provided by the present application has a simple preparation process and is suitable for industrial production.

[0097] It can be understood that the features between the method for preparing a lithium cobalt oxide composite material provided by the present application and the above-mentioned lithium cobalt oxide composite material are mutually applicable.

[0098] Using the lithium cobalt oxide composite material provided by the present application or the lithium cobalt oxide composite material prepared by the preparation method to prepare a positive electrode sheet in a lithium ion battery can effectively improve the volumetric energy density of the lithium ion battery.

[0099] In some examples, in step S10, the first sintering includes the following steps:

[0100] The first stage: Heat up to 600°C - 800°C at a rate of 3°C / min - 8°C / min, and keep the temperature for 2 h - 4 h;

[0101] The second stage: Then heat up to 1050°C - 1100°C at a rate of 1°C / min - 3°C / min, and keep the temperature for 5 h - 10 h.

[0102] It can be understood that in the first stage of the first sintering, the heating rate includes but is not limited to 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min; the holding temperature includes but is not limited to 600°C, 620°C, 650°C, 680°C, 700°C, 720°C, 750°C, 780°C, 800°C; the holding time includes but is not limited to 2 h, 2.2 h, 2.5 h, 2.8 h, 3 h, 3.2 h, 3.5 h, 3.8 h, 4 h. In the second stage of the first sintering, the heating rate includes but is not limited to 1°C / min, 1.2°C / min, 1.5°C / min, 1.8°C / min, 2°C / min, 2.2°C / min, 2.5°C / min, 2.8°C / min, 3°C / min; the holding temperature includes but is not limited to 1050°C, 1055°C, 1060°C, 1065°C, 1070°C, 1075°C, 1080°C, 1085°C, 1090°C, 1095°C, 1100°C; the holding time includes but is not limited to 5 h, 5.5 h, 6.0 h, 6.5 h, 7.0 h, 7.5 h, 8 h, 9 h, 10 h.

[0103] Adopt the two-stage sintering method to improve the electrical properties of the material.

[0104] In some of these examples, in step S10, the molar ratio of the first lithium source to the first cobalt source is 1.05 - 1.08:1.

[0105] It can be understood that the molar ratio refers to the ratio of the amount of substances; further, the molar ratio of the first lithium source to the first cobalt source includes but is not limited to 1.05:1, 1.06:1, 1.07:1, 1.08:1.

[0106] In some of these examples, in step S20, the second sintering includes the following steps:

[0107] The first stage: Heat up to 600°C - 800°C at a rate of 3°C / min - 8°C / min, and keep the temperature for 2 h - 4 h;

[0108] The second stage: Then heat up to 980°C - 1015°C at a rate of 1°C / min - 3°C / min, and keep the temperature for 5 h - 10 h.

[0109] It can be understood that in the first stage of the second sintering, the heating rate includes but is not limited to 3 °C / min, 4 °C / min, 5 °C / min, 6 °C / min, 7 °C / min, 8 °C / min; the holding temperature includes but is not limited to 600 °C, 620 °C, 650 °C, 680 °C, 700 °C, 720 °C, 750 °C, 780 °C, 800 °C; the holding time includes but is not limited to 2 h, 2.2 h, 2.5 h, 2.8 h, 3 h, 3.2 h, 3.5 h, 3.8 h, 4 h. In the second stage of the second sintering, the heating rate includes but is not limited to 1 °C / min, 1.2 °C / min, 1.5 °C / min, 1.8 °C / min, 2 °C / min, 2.2 °C / min, 2.5 °C / min, 2.8 °C / min, 3 °C / min; the holding temperature includes but is not limited to 980 °C, 985 °C, 990 °C, 995 °C, 1000 °C, 1005 °C, 1010 °C, 1015 °C; the holding time includes but is not limited to 5 h, 5.5 h, 6.0 h, 6.5 h, 7.0 h, 7.5 h, 8 h, 9 h, 10 h.

[0110] In some of these examples, in step S20, the molar ratio of the second lithium source to the second cobalt source is 1.05 to 1.08:1.

[0111] It can be understood that the molar ratio of the second lithium source to the second cobalt source includes but is not limited to 1.05:1, 1.06:1, 1.07:1, 1.08:1.

[0112] In some of these examples, in steps S10 and S20, the first cobalt source and the second cobalt source each independently include at least one of cobalt tetroxide, cobalt hydroxide, cobaltous oxide, cobalt nitrate, cobalt carbonate, cobalt oxalate, and cobalt oxyhydroxide.

[0113] In some of these examples, in steps S10 and S20, the first lithium source and the second lithium source each independently include at least one of lithium carbonate, lithium nitrate, lithium acetate, lithium hydroxide, and lithium fluoride.

[0114] In some of these examples, in steps S10 and S20, the first cobalt source and the second cobalt source each independently contain a doping element Q. Optionally, the doping element Q includes at least one of aluminum, magnesium, nickel, manganese, titanium, yttrium, lanthanum, and zirconium. Optionally, the doping amount of the doping element Q is 3000 ppm to 15000 ppm.

[0115] In some of these examples, in steps S10 and S20, in the step of mixing the first cobalt source and the first lithium source, there is also a step of adding a first dopant; and / or, in the step of mixing the second cobalt source and the second lithium source, there is also a step of adding a second dopant.

[0116] Optionally, the first dopant and the second dopant each independently include at least one of a doping element M and a doping element E. The doping element M is selected from at least one of magnesium, tungsten, titanium, yttrium, aluminum, nickel, manganese, lanthanum, niobium, vanadium, molybdenum, and zirconium, and the doping element E is selected from at least one of fluorine, chlorine, and sulfur elements.

[0117] In some of these examples, in step S30, the third sintering includes the following steps:

[0118] Heat up to 700°C to 900°C at a rate of 3°C / min to 8°C / min and keep the temperature for 5 h to 10 h.

[0119] It can be understood that in the third sintering, the heating rate includes but is not limited to 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min; the holding temperature includes but is not limited to 700°C, 720°C, 750°C, 780°C, 800°C, 820°C, 850°C, 880°C, 900°C; the holding time includes but is not limited to 5 h, 5.5 h, 6.0 h, 6.5 h, 7.0 h, 7.5 h, 8 h, 9 h, 10 h.

[0120] It can be understood that the third sintering temperature is relatively low, and has little influence on the particle size and morphology of the first lithium cobaltate and the second lithium cobaltate.

[0121] In some of these examples, in step S30, in the step of mixing the first lithium cobaltate and the second lithium cobaltate, the step of adding a coating agent is further included.

[0122] Coat the first lithium cobaltate and the second lithium cobaltate to improve the electrical properties of the material.

[0123] Optionally, the coating agent includes a third cobalt source and a third dopant. The third cobalt source includes at least one of cobalt tetroxide, cobalt hydroxide, cobaltous oxide, cobalt nitrate, nano-cobalt carbonate, and cobalt oxyhydroxide.

[0124] Optionally, the third dopant includes a doping element R. The doping element R is selected from at least one of magnesium, tungsten, titanium, yttrium, aluminum, nickel, manganese, lanthanum, vanadium, molybdenum, strontium, germanium, niobium, indium, zirconium, and halogen elements.

[0125] Optionally, the mass of the third cobalt source is 0.25% to 0.75% of the total mass of the first lithium cobaltate and the second lithium cobaltate.

[0126] It can be understood that the percentage of the mass of the third cobalt source in the total mass of the first lithium cobaltate and the second lithium cobaltate includes but is not limited to 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, 0.55%, 0.60%, 0.65%, 0.70%, 0.75%.

[0127] Optionally, the mass of the third dopant is 500 ppm to 8000 ppm of the total mass of the first lithium cobaltate and the second lithium cobaltate.

[0128] It can be understood that the mass fraction of the third dopant in the total mass of the first lithium cobaltate and the second lithium cobaltate includes but is not limited to 500 ppm, 2000 ppm, 3000 ppm, 5000 ppm, 6500 ppm, and 8000 ppm.

[0129] In some of these examples, in the method for preparing the lithium cobaltate composite material, the roasting atmospheres of the first sintering, the second sintering, and the third sintering are independently air, oxygen, or nitrogen respectively.

[0130] It can be understood that this application does not limit the calcination equipment for the first sintering, the second sintering, and the third sintering, and independently includes at least one of a muffle furnace, a tunnel furnace, a roller hearth kiln, a tube furnace, etc.

[0131] One embodiment of this application provides an electrode plate, including the above-mentioned lithium cobaltate composite material or the lithium cobaltate composite material prepared by the above-mentioned method for preparing the lithium cobaltate composite material.

[0132] The electrode plate provided by this application, including the above-mentioned lithium cobaltate composite material or the lithium cobaltate composite material prepared by the above-mentioned method for preparing the lithium cobaltate composite material, can endow the electrode plate with the same advantages as the lithium cobaltate composite material.

[0133] In some of these examples, the electrode plate includes a positive electrode plate.

[0134] One embodiment of this application provides a battery, including the above-mentioned electrode plate.

[0135] The battery provided by this application has a relatively high volume energy density, a relatively high discharge capacity, and a relatively good cycle retention rate.

[0136] In some of these examples, the battery includes a lithium-ion battery.

[0137] Furthermore, the lithium-ion battery includes a positive electrode plate, a negative electrode plate, a separator, and an electrolyte, and the positive electrode plate is the above-mentioned electrode plate.

[0138] It can be understood that this application does not limit the types of the negative electrode plate, the separator, and the electrolyte.

[0139] One embodiment of this application provides an electrical device, including the above-mentioned battery.

[0140] It can be understood that the battery is used to provide electrical energy.

[0141] The embodiments of the present invention will be described in detail below in conjunction with examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. For those not specified in the examples, they are carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments not specified for the manufacturer are all conventional products that can be obtained through commercial purchases.

[0142] Example 1

[0143] (1) Mix 3 kg of the first cobalt source Co3O4 (as shown in Table 3, D50 = 3.87 μm, Ti content in the precursor is 3000 ppm), 1.49 kg of Li2CO3, and 19.0 g of MgO in a high-speed mixer at 1000 r / min for 45 min. Among them, the lithium-cobalt ratio is 1.08:1, the content of MgO is 1300 ppm, and it is heated to 700 °C at a heating rate of 4 °C / min in the first stage and held for 3 h, and then heated to 1070 °C at a heating rate of 3 °C / min in the second stage and held for 8 h, and naturally cooled to room temperature. It is crushed to a particle size D50 of 18.9 μm of lithium cobaltate powder to obtain the first lithium cobaltate material Li 1.08 Co 0.967 Mg 0.002 Ti 0.004 O2;

[0144] (2) Mix 3 kg of the second cobalt source Co3O4 (D50 = 3.87 μm, Ti content is 3000 ppm), 1.44 kg of Li2CO3, and 7.2 g of Y2O3 in a high-speed mixer at 900 r / min for 45 min. Among them, the lithium-cobalt ratio is 1.05:1, the content of Y2O3 is 1500 ppm, and it is heated to 600 °C at a heating rate of 4 °C / min in the first stage and held for 4 h, and then heated to 1000 °C at a heating rate of 3 °C / min in the second stage and held for 8 h, and naturally cooled to room temperature. It is crushed to a particle size D50 of 5.0 μm of lithium cobaltate powder to obtain the second lithium cobaltate material Li 1.05 Co 0.975 Ti 0.004 Y 0.003 O2;

[0145] (3) Mix 1.2 kg of the first lithium cobaltate material prepared in step (1), 0.3 kg of the second lithium cobaltate material prepared in step (2), 70 g of nano-cobalt carbonate, and 1.9 g of Y2O3 in a high-speed mixer at 1100 r / min for 45 min. Among them, the content of Y2O3 is 1000 ppm, and it is heated to 900 °C at a heating rate of 2 °C / min and held for 6 h, and naturally cooled to room temperature to obtain the lithium cobaltate composite material Li 1.02 Co 0.98 Mg0.002 Ti 0.004 Y 0.002 O2, with a radial distance of 1.575 and a particle size D50 of 15.5 μm. The particle size distribution of the lithium cobalt oxide composite material is as Figure 1 shown.

[0146] Example 2

[0147] (1) Mix 3 kg of the first cobalt source Co3O4 (D50 = 3.9 μm, Al content is 8000 ppm), 1.45 kg of Li2CO3, 14.6 g of MgO and 5.02 g of LiF in a high-speed mixer at 1000 r / min for 45 min. Among them, the lithium-cobalt ratio is 1.06:1, the content of MgO is 1000 ppm, and it is heated to a temperature of 700 °C at a heating rate of 4 °C / min in the first stage and held for 3 h, and then heated to a temperature of 1076 °C at a heating rate of 3 °C / min in the second stage and held for 8 h, and naturally cooled to room temperature, and crushed to a particle size D50 of 18.7 μm of the lithium cobalt oxide powder to obtain the first lithium cobalt oxide material Li 1.06 Co 0.971 Al 0.011 Mg 0.002 O 1.994 F 0.006 ;

[0148] (2) Mix 3 kg of the second cobalt source Co3O4 (D50 = 3.87 μm, Ti content is 3000 ppm), 1.44 kg of Li2CO3 and 7.2 g of Y2O3 in a high-speed mixer at 900 r / min for 45 min. Among them, the lithium-cobalt ratio is 1.05:1, the content of Y2O3 is 1500 ppm, and it is heated to a temperature of 600 °C at a heating rate of 4 °C / min in the first stage and held for 4 h, and then heated to a temperature of 1000 °C at a heating rate of 3 °C / min in the second stage and held for 8 h, and naturally cooled to room temperature, and crushed to a particle size D50 of 5.0 μm of the lithium cobalt oxide powder to obtain the second lithium cobalt oxide material Li 1.05 Co 0.975 Ti 0.004 Y 0.003 O2;

[0149] (3) Mix 1.2 kg of the first lithium cobalt oxide material prepared in step (1), 0.4 kg of the second lithium cobalt oxide material prepared in step (2), 64 g of nano-cobalt carbonate and 1.13 g of La2O3 in a high-speed mixer at 1100 r / min for 45 min. Among them, the content of La2O3 is 600 ppm, and it is heated to a temperature of 900 °C at a heating rate of 2 °C / min and held for 6 h, and naturally cooled to room temperature to obtain the lithium cobalt oxide composite material Li 1.02 Co 0.975 Al 0.009Mg 0.001 Ti 0.005 Y 0.002 La 0.001 O 1.995 F 0.005 with a particle size distribution distance of 1.59 and a particle size D50 of 15.3 μm.

[0150] Example 3

[0151] (1) Mix 3 kg of the first cobalt source Co3O4 (D50 = 4.1 μm, Al content of 7000 ppm), 1.47 kg of Li2CO3, and 18.0 g of MgO in a high-speed mixer at 1000 r / min for 45 min. Among them, the lithium-cobalt ratio is 1.07:1, and the content of MgO is 1300 ppm. Heat it to 700 °C at a heating rate of 4 °C / min in the first stage, hold for 3 h, heat it to 1072 °C at a heating rate of 3 °C / min in the second stage, hold for 8 h, cool naturally to room temperature, and crush it to a particle size D50 of 19 μm for the lithium cobaltate powder to obtain the first lithium cobaltate material Li 1.07 Co 0.965 Al 0.010 Mg 0.002 O2;

[0152] (2) Mix 3 kg of the second cobalt source Co3O4 (D50 = 3.87 μm, Ti content of 3000 ppm), 1.44 kg of Li2CO3, and 7.2 g of Y2O3 in a high-speed mixer at 900 r / min for 45 min. Among them, the lithium-cobalt ratio is 1.05:1, and the content of Y2O3 is 1500 ppm. Heat it to 600 °C at a heating rate of 4 °C / min in the first stage, hold for 4 h, heat it to 1000 °C at a heating rate of 3 °C / min in the second stage, hold for 8 h, cool naturally to room temperature, and crush it to a particle size D50 of 5.0 μm for the lithium cobaltate powder to obtain the second lithium cobaltate material Li 1.05 Co 0.979 Ti 0.002 Y 0.002 O2;

[0153] (3) Mix 1.2 kg of the first lithium cobaltate material prepared in step (1), 0.24 kg of the second lithium cobaltate material prepared in step (2), 70 g of nano-cobalt carbonate, 0.78 g of ZrO2, and 2.25 g of LiF in a high-speed mixer at 1100 r / min for 45 min. Among them, the content of ZrO2 is 400 ppm, and heat it to 900 °C at a heating rate of 2 °C / min, hold for 6 h, cool naturally to room temperature to obtain the lithium cobaltate composite material Li 1.025 Co 0.979 Al 0.008 Mg 0.002Ti 0.001 Y 0.001 La 0.001 O 1.996 F 0.004 , the particle size distribution is 1.559, and the particle size D50 is 15.8 μm.

[0154] Example 4

[0155] It is basically the same as Example 1, except that in step (1), the D50 particle size of the first cobalt source Co3O4 is 5 μm, and it is crushed to a particle size D50 of 15.0 μm for the lithium cobaltate powder to obtain the first lithium cobaltate material; the lithium cobaltate composite material Li 1.02 Co 0.98 Mg 0.002 Ti 0.004 Y 0.002 O2 has a particle size distribution of 1.713 and a particle size D50 of 13.6 μm.

[0156] Comparative Example 1

[0157] It is basically the same as Example 1, except that in step (1), the D50 particle size of the first cobalt source Co3O4 is 16.6 μm, and step (1) is as follows:

[0158] (1) Mix 3 kg of the first cobalt source Co3O4 (as shown in Table 3, D50 = 16.6 μm, Ti content is 3000 ppm), 1.49 kg of Li2CO3 and 19.0 g of MgO in a high-speed mixer at 1000 r / min for 45 min, where the lithium-cobalt ratio is 1.08:1, the content of MgO is 1300 ppm, and heat it to a temperature of 700 °C at a heating rate of 4 °C / min in the first stage, hold for 3 h, heat it to a temperature of 1070 °C at a heating rate of 3 °C / min in the second stage, hold for 8 h, cool naturally to room temperature, and crush it to a particle size D50 of 18.9 μm for the lithium cobaltate powder to obtain the first lithium cobaltate material.

[0159] Comparative Example 2

[0160] It is basically the same as Example 2, except that in step (1), the D50 particle size of the first cobalt source Co3O4 is 16.5 μm.

[0161] Comparative Example 3

[0162] It is basically the same as Example 3, except that in step (1), the D50 particle size of the first cobalt source Co3O4 is 16.8 μm.

[0163] Comparative Example 4

[0164] It is basically the same as Example 4, except that in step (1), the D50 particle size of the first cobalt source Co3O4 is 13.9 μm.

[0165] The particle size distribution of the first cobalt source Co3O4 used in step (1) of Example 1 and Comparative Example 1 is shown in Table 1.

[0166] Table 1

[0167]

[0168] The particle size distribution of the first lithium cobaltate material prepared in step (1) of Example 1 and Comparative Example 1, Example 4 and Comparative Example 4 is as Figure 2 and Table 2 shows.

[0169] Table 2

[0170]

[0171] The particle size distribution of the second lithium cobaltate material prepared in step (2) of Example 1 is as Figure 3 and Table 3 shows.

[0172] Table 3

[0173]

[0174] The electron micrograph of the first cobalt source Co3O4 used in step (1) of Example 1 is as Figure 4 shown, and the electron micrograph of the first cobalt source Co3O4 used in step (1) of Comparative Example 1 is as Figure 5 shown.

[0175] The particle size distribution of the lithium cobaltate composite material prepared in step (3) of Example 1 and Comparative Example 1 is as Figure 1 and Table 4 shows.

[0176] Table 4

[0177]

[0178] The powder compaction density of the lithium cobaltate composite materials prepared in each example and comparative example under 200 MPa is shown in Table 5; the ultimate compaction density of the lithium cobaltate composite materials prepared in each example and comparative example made into full electrode sheets is shown in Table 5.

[0179] Table 5

[0180]

[0181] It can be seen from Table 5 that compared with Comparative Examples 1-4, the powder compaction density and the electrode sheet compaction density of Examples 1-4 have been significantly improved.

[0182] Electrical performance test

[0183] (1) Preparation of the positive electrode sheet: The lithium cobaltate composite materials obtained in each example and comparative example were uniformly mixed with the conductive agent acetylene black (Super P) and polyvinylidene fluoride PVDF in a mass ratio of 8:1:1. The above mixture was made into a slurry with N-methyl-pyrrolidone (NMP), then evenly coated on aluminum foil, taken out and pressed into tablets after vacuum drying, and cut into positive electrode sheets;

[0184] (2) Preparation of the lithium-ion half-cell: The lithium-ion battery was assembled from the above positive electrode sheet, lithium sheet negative electrode, separator between the positive and negative electrodes, and electrolyte. The assembled battery was used for capacity testing and cycle testing. The capacity test results at RT, 3.0 - 4.58V and the cycle performance results at 45°C, 4.60V are shown in Table 6.

[0185] Table 6

[0186]

[0187] As can be seen from Table 6, compared with the comparative example, the comprehensive discharge performance of the examples is better.

[0188] The technical features of the above-described examples can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above examples are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0189] The above-described examples only represent several implementation manners of the present application, which are convenient for understanding the technical solutions of the present application specifically and in detail, but should not be construed as a limitation on the protection scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments based on the technical solutions provided by the present application are all within the protection scope of the appended claims of the present application. Therefore, the protection scope of the patent of the present application should be subject to the content of the appended claims, and the specification can be used to explain the content of the claims.

Claims

1. A lithium cobalt oxide composite material, characterized in that: The lithium cobalt oxide composite material comprises a lithium cobalt oxide core and a shell coated on at least a portion of the surface of the lithium cobalt oxide core, wherein the lithium cobalt oxide core comprises a first lithium cobalt oxide and a second lithium cobalt oxide; The median particle size of the first lithium cobaltate is d1, the median particle size of the second lithium cobaltate is d2, the median particle size of the first cobalt source as a precursor of the first lithium cobaltate is d3, 3 μm≤d3≤5 μm; the median particle size of the second cobalt source as a precursor of the second lithium cobaltate is d4, 3 μm≤d4≤5 μm; Among them, 10μm≤d1-d3≤17μm; 0μm≤d2-d4≤3μm.

2. The lithium cobalt oxide composite material according to claim 1, characterized in that 15μm≤d1≤20μm; and / or, 3 μm ≤ d2 ≤ 6 μm; And / or, the diameter distance of the first lithium cobalt oxide is 1.0-1.5; And / or, the mass ratio of the first lithium cobalt oxide to the second lithium cobalt oxide is 3-5:

1.

3. The lithium cobalt oxide composite material according to claim 1, characterized in that The median particle size of the lithium cobalt oxide composite material is 13 μm to 18 μm; And / or, the diameter distance of the lithium cobalt oxide composite material is 1.5-1.8; And / or, the powder compaction density of the lithium cobalt oxide composite material at 200 MPa is ≥ 4.1 g / cm 3 ; And / or, the pole piece ultimate compaction density of the lithium cobalt oxide composite material is ≥4.2 g / cm 3 .

4. The lithium cobalt oxide composite material according to any one of claims 1 to 3, characterized in that The chemical formula of the lithium cobalt oxide composite material is Li u Co v M x Q y R γ O2E z ; wherein, 1.00<u≤1.07, 0.95<v≤1, 0≤x<1, 0≤y<1, 0≤γ<0.1, 0≤z<0.1, M includes at least one of magnesium, tungsten, titanium, yttrium, aluminum, nickel, manganese, lanthanum, niobium, vanadium, molybdenum and zirconium, E includes at least one of fluorine, chlorine and sulfur, Q includes at least one of aluminum, magnesium, nickel, manganese, titanium, yttrium, lanthanum and zirconium, and R includes at least one of magnesium, tungsten, titanium, yttrium, aluminum, nickel, manganese, lanthanum, vanadium, molybdenum, strontium, germanium, niobium, indium, zirconium and halogen elements.

5. A method for preparing a lithium cobalt oxide composite material, characterized in that: The following steps are involved: After mixing the first cobalt source and the first lithium source, first sintering and crushing are performed in sequence to prepare a first lithium cobaltate, wherein the median particle size of the first lithium cobaltate is d1, the median particle size of the first cobalt source is d3, 3 μm≤d3≤5 μm, 10 μm≤d1-d3≤17 μm; After mixing the second cobalt source and the second lithium source, performing a second sintering and crushing in sequence to prepare a second lithium cobaltate, wherein the median particle size of the second lithium cobaltate is d2, and the median particle size of the second cobalt source is d4, 3 μm≤d4≤5 μm, 0 μm≤d2-d4≤3 μm; The first lithium cobalt oxide and the second lithium cobalt oxide are mixed, and then subjected to third sintering and crushing in sequence to prepare a lithium cobalt oxide composite material.

6. The method for preparing the lithium cobalt oxide composite material according to claim 5, characterized in that: The first sintering comprises the following steps: Raise the temperature to 600℃~800℃ at a rate of 3℃ / min~8℃ / min, and keep it at that temperature for 2 h~4 h; then raise the temperature to 1050℃~1100℃ at a rate of 1℃ / min~3℃ / min, and keep it at that temperature for 5 h~10 h; And / or, the second sintering comprises the following steps: Heat up to 600-800°C at a rate of 3-8°C / min, keep warm for 2-4 hours, then heat up to 980-1015°C at a rate of 1-3°C / min, keep warm for 5-10 hours; And / or, the third sintering comprises the following steps: Raise the temperature to 700℃~900℃ at a rate of 3℃ / min~8℃ / min and keep it at this temperature for 5 h~10 h.

7. The method for preparing the lithium cobalt oxide composite material according to claim 5, characterized in that: The first cobalt source and the second cobalt source independently include at least one of cobalt tetroxide, cobalt hydroxide, cobaltous oxide, cobalt nitrate, cobalt carbonate, cobalt oxalate and cobalt oxyhydroxide; And / or, the first lithium source and the second lithium source independently include at least one of lithium carbonate, lithium nitrate, lithium acetate, lithium hydroxide and lithium fluoride; And / or, the molar ratio of the first lithium source to the first cobalt source is 1.05-1.08:1; And / or, the molar ratio of the second lithium source to the second cobalt source is 1.05-1.08:

1.

8. The method for preparing the lithium cobalt oxide composite material according to claim 5, characterized in that: The preparation method meets at least one of the following characteristics: (1) The first cobalt source and the second cobalt source each independently contain a doping element Q; optionally, the doping element Q comprises at least one of aluminum, magnesium, nickel, manganese, titanium, yttrium, lanthanum and zirconium; optionally, the doping amount of the doping element Q is 3000 ppm to 15000 ppm; (2) the step of mixing the first cobalt source and the first lithium source further comprises the step of adding a first dopant; and / or the step of mixing the second cobalt source and the second lithium source further comprises the step of adding a second dopant; optionally, the first dopant and the second dopant respectively and independently comprise at least one of a doping element M and a doping element E, the doping element M being selected from at least one of magnesium, tungsten, titanium, yttrium, aluminum, nickel, manganese, lanthanum, niobium, vanadium, molybdenum and zirconium, and the doping element E being selected from at least one of fluorine, chlorine and sulfur; (3) The step of mixing the first lithium cobalt oxide and the second lithium cobalt oxide further comprises the step of adding a coating agent; optionally, the coating agent comprises a third cobalt source and a third dopant, the third cobalt source comprises at least one of cobalt tetraoxide, cobalt hydroxide, cobaltous oxide, cobalt nitrate, nano-cobalt carbonate and cobalt oxyhydroxyl, the third dopant comprises a doping element R, and the doping element R is selected from at least one of magnesium, tungsten, titanium, yttrium, aluminum, nickel, manganese, lanthanum, vanadium, molybdenum, strontium, germanium, niobium, indium, zirconium and halogen elements; and / or, the mass of the third cobalt source is 0.25% to 0.75% of the total mass of the first lithium cobalt oxide and the second lithium cobalt oxide; and / or, the mass of the third dopant is 500 ppm to 8000 ppm of the total mass of the first lithium cobalt oxide and the second lithium cobalt oxide.

9. An electrode plate, characterized in that: The invention comprises a lithium cobalt oxide composite material as claimed in any one of claims 1 to 4 or a lithium cobalt oxide composite material prepared by the preparation method of the lithium cobalt oxide composite material as claimed in any one of claims 5 to 8.

10. A battery, characterized in that: Comprising the electrode plate as described in claim 9.

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