Lithium ion battery positive electrode material and preparation method therefor, lithium ion battery, and electric device

Abstract

The present application relates to a lithium ion battery positive electrode material, comprising a positive electrode material matrix and a composite coating layer covering the surface of the positive electrode material matrix, wherein the composite coating layer comprises a perovskite type oxide, a perovskite-like oxide, and LiCoO2.

Description

Lithium ion battery cathode material, preparation method thereof, lithium ion battery and electric device

[0001] Related applications

[0002] The present application claims priority to the Chinese patent application No. 2024106357618, filed on May 22, 2024, and entitled "Lithium ion battery cathode material, preparation method thereof, lithium ion battery and electric device", the contents of which are hereby incorporated by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the field of lithium ion batteries, in particular to a high-voltage ternary lithium ion battery cathode material, a preparation method thereof, a lithium ion battery and an electric device. BACKGROUND

[0004] In recent years, the new energy vehicle market has experienced explosive growth, which not only promotes the popularization of electric vehicles, but also promotes the development of related industrial chains. As the main material of lithium ion batteries, cathode materials have also developed rapidly. As consumers' performance requirements for electric vehicles become higher and higher, especially for the index of endurance mileage. In order to meet the needs of users for longer endurance mileage, cathode material manufacturers continue to improve the specific capacity performance of cathode materials.

[0005] At present, the main way to improve the capacity is to improve the application voltage of the material. The delithiation amount of ternary cathode material is higher at high voltage, thereby improving the specific capacity performance; but due to deeper electron transfer, more Ni 4+ , high-valence nickel ions are prone to side reactions, causing material phase transformation and oxygen evolution. In addition, the degree of lithium ion deintercalation increases at high voltage, resulting in greater volume change and lattice stress of the material, ultimately causing the material to crack and react with the electrolyte, thereby exacerbating phase transformation and oxygen evolution. The above failure behaviors will cause the cathode material to decay more rapidly, affecting the application prospect of ternary cathode materials at high voltage.

[0006] Therefore, it is urgent to develop a high-voltage ternary cathode material that can improve performance, alleviate failure behaviors, and improve the performance of the material at high voltage. SUMMARY

[0007] According to at least some embodiments of the present application, a high-voltage ternary lithium ion battery cathode material is provided, and the present application also provides a preparation method of the high-voltage ternary lithium ion battery cathode material, a lithium ion battery comprising the high-voltage ternary lithium ion battery cathode material, and an electric device comprising the lithium ion battery.

[0008] In a first aspect, a lithium ion battery cathode material is provided, comprising a cathode material matrix and a composite coating layer coated on the surface of the cathode material matrix, wherein the composite coating layer comprises a perovskite type oxide, a perovskite-like type oxide and LiCoO2.

[0009] Optionally, the perovskite type oxide comprises an ABO3 type perovskite oxide with oxygen vacancies, having a chemical formula of Y d ZrO 3-f wherein Y is one or both of Ca and Sr, 0.5≤d<1, and 0

[0010] Optionally, the perovskite-like type oxide comprises an A2BO4 type perovskite-like oxide with oxygen vacancies, having a chemical formula of X e Y 2-e M2O 4-g wherein X is at least one of La, Ce, Pr, Gd and Yb, Y is one or both of Ca and Sr, M2 is one or both of Ni and Co, 1≤e<2, and 0

[0011] Optionally, the perovskite-like type oxide further comprises a Li-doped A2BO4 type perovskite-like oxide X2Li m M2 1- m O 4-n wherein 0

[0012] Optionally, the thickness of the composite coating layer is 0.03 μm to 0.3 μm.

[0013] Optionally, the lithium ion battery cathode material has a median particle size D50 of 2 μm to 5 μm, and a specific surface area of 0.5 m 2 / g to 1.2 m 2 / g.

[0014] Optionally, the cathode material matrix has a chemical formula of Li 1+a Ni x Co y Mn 1-x-y-b M1 b O z wherein M1 is a doping element selected from at least two of Zr, Al, Co, W, Nb, Y and Sr, 0.5≤x≤0.95, 0.05≤y≤0.2, 0≤a≤0.2, 0

[0015] In a second aspect, a preparation method of the lithium ion battery cathode material of the first aspect is provided, comprising:

[0016] The positive electrode material base, cobalt source, zirconium source, X-containing coating agent, Y-containing coating agent are mixed, and then high-temperature sintering is performed to obtain the lithium ion battery positive electrode material, wherein the high-temperature sintering temperature is 600-900°C, the time is 4-12h, and the high-temperature sintering is performed in an atmosphere with an oxygen concentration of 40%-80%. If the oxygen concentration is too low, the oxidation reaction of the perovskite material is incomplete, which is not conducive to the growth of the crystal; and if the oxygen concentration is too high, it is difficult to form oxygen vacancies in the perovskite material.

[0017] Optionally, the cobalt source is selected from one or more of cobaltous hydroxide, cobalt hydroxide, cobalt oxide, cobalt sulfate, and cobalt acetate; wherein the mass fraction of Co element in the cobalt source relative to the positive electrode material base is 3500-35000ppm.

[0018] Optionally, the zirconium source is selected from one or both of zirconium oxide and zirconium sulfate; wherein the mass fraction of Zr element in the zirconium source relative to the positive electrode material base is 300-3000ppm.

[0019] Optionally, the X-containing coating agent is selected from one or more of oxides, hydroxides, chlorides, carbonates, and nitrates containing element X; wherein the mass fraction of X element in the X-containing coating agent relative to the positive electrode material base is 1500-4500ppm.

[0020] Optionally, the Y-containing coating agent is selected from one or more of oxides, hydroxides, chlorides, carbonates, and nitrates containing element Y; wherein the mass fraction of Y element in the Y-containing coating agent relative to the positive electrode material base is 1000-4000ppm.

[0021] Optionally, the positive electrode material base is obtained by mixing a ternary hydroxide precursor, a lithium source, and a M1-containing dopant, and then sintering, wherein the lithium source is selected from one or more of lithium hydroxide, lithium carbonate, lithium fluoride, and lithium acetate, the molar ratio of the lithium source to the ternary hydroxide precursor is 1.01-1.11, the mass fraction of M1 element in the M1-containing dopant relative to the ternary hydroxide precursor is 1000-8000ppm, the sintering temperature is 700-1100°C, the sintering time is 8-16h, and the sintering is performed in an oxygen atmosphere with an oxygen concentration of greater than 95%, which can promote the crystallization of the particles.

[0022] In a third aspect, a lithium ion battery is provided, wherein the positive electrode material of the lithium ion battery is the lithium ion battery positive electrode material as described in the first aspect or obtained by the preparation method as described in the second aspect.

[0023] In a fourth aspect, a power consuming device is provided, which comprises the lithium ion battery as described in the third aspect, and the power consuming device comprises a secondary battery or a battery pack of the lithium ion battery provided or composed by the power consuming device itself as a power source or a part of a power source, or the lithium ion battery is made into a simple power supply device.

[0024] The details of one or more embodiments of the application are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the application will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description only represent the embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of the disclosed drawings.

[0026] Fig. 1 is a scanning electron microscope image of the lithium ion battery anode material prepared in Embodiment 1 of the present application;

[0027] Fig. 2 is an XRD spectrum of the lithium ion battery anode material prepared in Embodiment 1 of the present application;

[0028] Figs. 3-5 are transmission electron microscope images of the lithium ion battery anode material prepared in Embodiment 1 of the present application;

[0029] Fig. 6 is a discharge curve of the lithium ion battery anode material prepared in Embodiment 1 and Comparative Example 1 of the present application;

[0030] Fig. 7 is a DCR comparison chart of the lithium ion battery anode material prepared in Embodiment 1 and Comparative Example 1 of the present application at different SOC;

[0031] Fig. 8 is a high-temperature cycle curve of the lithium ion battery anode material prepared in Embodiment 1 and Comparative Example 1 of the present application;

[0032] Fig. 9 is a DSC curve of the lithium ion battery anode material prepared in Embodiment 1 and Comparative Example 1 of the present application;

[0033] Fig. 10 is a soft package battery gas production chart of the lithium ion battery anode material prepared in Embodiment 1 and Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0034] In order to make the above objectives, features and advantages of the present application more clear and understandable, the detailed description of the specific embodiments of the present application is made below in conjunction with the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in many different ways from what is described herein, and by one of ordinary skill in the art without departing from the spirit of the present application, and therefore the present application is not limited to the specific embodiments disclosed below.

[0035] Unless otherwise required by context, the term "including" as used in the specification and the claims is to be interpreted as open, meaning "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "an exemplary embodiment", "exemplary embodiments", or "some examples" are intended to mean that a particular feature, structure, material, or characteristic is included in at least one embodiment or example of the disclosure, but not necessarily in all embodiments or examples. The appearance of the above terms in various places in the specification is not necessarily intended to refer to the same embodiment or example. In addition, the particular features, structures, materials, or characteristics described can be included in any suitable way in any one or more embodiments or examples.

[0036] Exemplary embodiments are described herein with reference to cross-sectional and / or plan view illustrations that are schematic illustrations of idealized embodiments. In the drawings, the thickness of layers and regions are exaggerated for clarity. Accordingly, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and / or tolerances, are to be expected. Thus, the exemplary embodiments should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an etched region illustrated as a rectangle will typically have rounded or curved features. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region of a device and are not intended to limit the scope of the exemplary embodiments.

[0037] In this document, "one or more" means one or more than or equal to two, unless otherwise stated.

[0038] In this document, "for example", "for instance", "such as", "like", "exemplary", "illustrative" and "for example" are used to describe technical solutions, and should not be understood as limiting the prior technical solutions, nor should they be understood as limiting the scope of protection of this document. In this document, unless otherwise stated, A (such as B) means that B is one non-limiting example of A, and it can be understood that A is not limited to B.

[0039] In this document, "optionally", "optional", "option" means that it can or can not exist, that is, it means to select from two parallel schemes of "have" or "have not". If there are multiple "options" in a technical solution, and there is no contradiction or mutual restriction, each "option" is independent unless otherwise stated.

[0040] In the present document, the terms "first", "second", "third", "fourth" and the like in the description and in the claims, are used for descriptive purposes only and not to be construed as indicating or implying relative importance or quantities.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application.

[0042] In the present document, the technical features described in an open way include both the closed technical solutions consisting of the listed features and the open technical solutions including the listed features.

[0043] In the present document, in relation to a numerical interval (i.e. a numerical range), unless otherwise specified, the distribution of the selectable values within the numerical interval is considered to be continuous and includes both numerical end points (i.e. the minimum value and the maximum value) of the numerical interval and every value between the two numerical end points. Unless otherwise specified, when a numerical interval refers only to integers within the numerical interval, including both end point integers and every integer between the two end point integers, it is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe a feature or a characteristic, these numerical ranges can be combined. In other words, unless otherwise indicated, the numerical ranges disclosed herein are to be interpreted as including any and all subranges within the numerical ranges. The "numerical" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. The "numerical interval" is allowed to be broadly interpreted as including numerical interval types such as percentage interval, ratio interval, value interval, etc.

[0044] In the present document, in relation to a method flow involving multiple steps, unless otherwise specified, the execution of these steps does not have strict order restrictions and can be executed in other orders than described. Moreover, any step can include multiple sub-steps or multiple stages, which do not necessarily have to be executed at the same time but can be executed at different times, and the execution order does not necessarily have to be sequential but can be executed in rotation or alternation or simultaneously with other steps or sub-steps or stages of other steps.

[0045] In order to solve the above technical problems, in a first aspect, some embodiments of the present application provide a lithium ion battery cathode material, comprising a cathode material base body and a composite coating layer coated on the surface of the cathode material base body, the composite coating layer comprising a perovskite oxide, a perovskite-like oxide and LiCoO2.

[0046] The perovskite-type oxide, the perovskite-type oxide and LiCoO2 all have oxygen vacancies, and the perovskite-type oxide, the perovskite-type oxide and LiCoO2 can be uniformly coated on the surface of the positive electrode material matrix, which can reduce the side reaction between the electrolyte and the positive electrode material matrix, thereby reducing the harmful phase change of the material and reducing the oxygen evolution, thereby reducing the failure behavior at high voltage, and effectively improving the specific capacity, initial DCR and high-temperature cycle capacity retention rate of the lithium ion battery positive electrode material.

[0047] In some embodiments, the perovskite-type oxide described above includes an ABO3-type perovskite oxide with oxygen vacancies, which has a chemical formula of Y d ZrO 3-f , wherein Y is one or both of Ca and Sr, 0.5≤d<1, and 0

[0048] In some embodiments, the perovskite-type oxide described above includes an A2BO4-type perovskite oxide with oxygen vacancies, which has a chemical formula of X e Y 2-e M2O 4-g , wherein X is at least one of La, Ce, Pr, Gd and Yb, Y is one or both of Ca and Sr, M2 is one or both of Ni and Co, 1≤e<2, and 0

[0049] In some embodiments, the perovskite-type oxide described above further includes a Li-doped A2BO4-type perovskite oxide X2Li m M2 1-m O 4-n , wherein 0

[0050] In some embodiments, the thickness of the composite coating layer described above is 0.03 μm to 0.3 μm.

[0051] In some embodiments, the median particle size D50 of the lithium ion battery positive electrode material described above is 2 μm to 5 μm, and the specific surface area is 0.5 m 2 / g to 1.2 m 2 / g.

[0052] In some embodiments, the positive electrode material matrix has a chemical formula of Li 1+a Ni x Co y Mn 1-x-y-b M1 b O zwherein M1 is a doping element selected from at least two of Zr, Al, Co, W, Nb, Y and Sr, 0.5≤x≤0.95, 0.05≤y≤0.2, 0≤a≤0.2, 0<b≤0.1, 0.05≤1-x-y-b≤0.4, 1.8<z<2.2.

[0053] In a second aspect, some embodiments of the present application provide a preparation method of the lithium ion battery cathode material according to the first aspect, comprising:

[0054] The cathode material matrix, the cobalt source, the zirconium source, the X-containing coating agent and the Y-containing coating agent are mixed, and then high-temperature sintering is performed to obtain the lithium ion battery cathode material, wherein the high-temperature sintering is performed at a temperature of 600-900°C for 4-12 hours in an atmosphere with an oxygen concentration of 40-80%.

[0055] In the preparation method of the lithium ion battery cathode material provided in the embodiments of the present application, a lithium ion battery cathode material coated with a composite coating layer containing perovskite-type oxides, perovskite-type oxides and LiCoO2 can be prepared. The composite coating layer can effectively reduce the harmful phase change of the material and reduce the oxygen evolution, thereby reducing the failure behavior at high voltage and effectively improving the specific capacity, initial DCR and high-temperature cycle capacity retention rate of the lithium ion battery cathode material. If the oxygen concentration is too low, the oxidation reaction of the perovskite material is not complete, which is not conducive to the growth and crystallization of the perovskite material. If the oxygen concentration is too high, it is difficult for the perovskite material to form oxygen vacancies.

[0056] In some embodiments, the above-mentioned cobalt source is selected from one or more of cobaltous hydroxide, cobalt hydroxide, cobalt oxide, cobalt sulfate and cobalt acetate; wherein the mass fraction of Co element in the cobalt source relative to the cathode material matrix is 3500-35000 ppm.

[0057] In some embodiments, the above-mentioned zirconium source is selected from one or both of zirconium oxide and zirconium sulfate; wherein the mass fraction of Zr element in the zirconium source relative to the cathode material matrix is 300-3000 ppm.

[0058] In some embodiments, the above-mentioned X-containing coating agent is selected from one or more of oxides, hydroxides, chlorides, carbonates and nitrates containing element X; wherein the mass fraction of X element in the X-containing coating agent relative to the cathode material matrix is 1500-4500 ppm.

[0059] In some embodiments, the above-mentioned Y-containing coating agent is selected from one or more of oxides, hydroxides, chlorides, carbonates and nitrates containing element Y; wherein the mass fraction of Y element in the Y-containing coating agent relative to the cathode material matrix is 1000-4000 ppm.

[0060] In some embodiments, the positive electrode material substrate is obtained by mixing a ternary hydroxide precursor, a lithium source, and a M1-containing dopant, and then sintering, wherein the lithium source is selected from one or more of lithium hydroxide, lithium carbonate, lithium fluoride, and lithium acetate, the molar ratio of the lithium source to the ternary hydroxide precursor is 1.01-1.11, the mass fraction of M1 in the M1-containing dopant relative to the ternary hydroxide precursor is 1000-8000 ppm, the sintering temperature is 700-1100°C, the sintering time is 8-16 hours, and the sintering is performed in an oxygen atmosphere with an oxygen concentration greater than 95%, which can promote the crystallization of the particles.

[0061] In a third aspect, some embodiments of the present application further provide a lithium ion battery, which uses the lithium ion battery positive electrode material as described in the first aspect or the lithium ion battery positive electrode material prepared by the preparation method as described in the second aspect.

[0062] In a fourth aspect, some embodiments of the present application further provide a power consuming device, which includes the lithium ion battery as described in the third aspect. The power consuming device includes a lithium ion battery or a secondary battery or a battery pack composed of lithium ion batteries as a power source or part of a power source, or the lithium ion battery is made into a pure power supply device.

[0063] In order to objectively evaluate the technical effects of the present application, the present application will be described in detail by the following examples and comparative examples.

[0064] In the following examples and comparative examples, all raw materials can be purchased in commercial form, and in order to maintain the reliability of the experiments, the raw materials used in the following examples and comparative examples all have the same physical and chemical parameters or are prepared by the same treatment method.

[0065] Example 1:

[0066] A lithium ion battery positive electrode material includes a positive electrode material substrate and a composite coating layer coated on the surface of the positive electrode material substrate, and the composite coating layer includes a perovskite-type oxide Ca 0.8 ZrO 2.8 , a perovskite-type oxide La 1.5 Ca 0.5 CoO 3.75 , La2Li 0.4 Ni 0.6 O 3.9 , and LiCoO2, wherein the chemical formula of the positive electrode material substrate is Li 1.03 Ni 0.77 Co 0.05 Mn 0.18 Zr0.002 W 0.0008 Sr 0.0015 O2, the thickness of the coating layer is about 0.15 μm, the median particle size D50 of the lithium ion battery positive electrode material is about 3.5 μm, and the specific surface area is about 0.7 m 2 / g.

[0067] The preparation method of the lithium ion battery positive electrode material in the embodiment comprises the following steps:

[0068] (1) Preparation of a multi-element doped ternary positive electrode material matrix

[0069] Lithium source LiOH·H2O and Ni 0.75 Co 0.07 Mn 0.18 (OH)2 hydroxide precursor, and doping source ZrO2, WO3, SrO are mixed by a high-speed mixer, and the mixing time is 30 min to ensure uniform mixing; wherein the molar ratio of Li to transition metal (Li / Me) in the mixture is set to 1.03, the mass fraction of Zr element in ZrO2 relative to the precursor is 2000 ppm, the mass fraction of W element in WO3 relative to the precursor is 1600 ppm, and the mass fraction of Sr element in SrO relative to the ternary precursor is 1430 ppm.

[0070] After the mixing is completed, the obtained material is placed in a sintering furnace under an oxygen atmosphere, the oxygen concentration introduced is 98%, the temperature in the furnace is gradually increased from room temperature to 920°C at a heating rate of 3°C / min, and the sintering is kept at 920°C for 12 h, after the sintering is completed, the material is crushed and sieved to obtain a multi-element doped ternary positive electrode material matrix.

[0071] (2) Preparation of a lithium ion battery positive electrode material with a composite coating layer

[0072] The multi-element doped ternary positive electrode material matrix prepared in step (1) and Co(OH)2, La2O3, CaCO3, ZrO2 as coating sources are mixed by a high-speed mixer, and the mixing time is 30 min to ensure uniform mixing; wherein the mass fraction of Co element, La element, Ca element, Zr element in Co(OH)2, La2O3, CaCO3, ZrO2 relative to the ternary positive electrode material matrix is 14000 ppm, 3000 ppm, 1500 ppm, 2000 ppm, respectively.

[0073] After the mixing is completed, the obtained material is placed in a sintering furnace under an oxygen atmosphere, the oxygen concentration introduced is 60%, the temperature in the furnace is gradually increased from room temperature to 800°C at a heating rate of 3°C / min, and the sintering is kept at 800°C for 8 h to obtain a lithium ion battery positive electrode material.

[0074] FEI-SEM (field emission scanning electron microscope) test was performed on the lithium ion battery cathode material prepared in the embodiment, and the result is shown in Figure 1. It can be observed from Figure 1 that, due to the Co coating process in the second sintering process, the surface of the cathode material presents obvious wavy shape and small particle coexistence characteristics; the material particle dispersibility is good, the median particle size D50 of the material is about 3.5 μm by using Malvern 3000 to test, and the specific surface area of the material is about 0.7 m 2 / g by using a specific surface area tester.

[0075] XRD (X-ray diffraction) test was performed on the lithium ion battery cathode material prepared in the embodiment, and the test result is shown in Figure 2. It can be known from Figure 2 that the material has a typical ternary material structure, and the I (003) / I (104) of the material is 2.38, which reflects that the ternary material has excellent crystallinity and layered structure.

[0076] TEM (transmission electron microscope) test was performed on the lithium ion battery cathode material prepared in the embodiment, and the transmission results at different positions are shown in Figures 3-5. It can be observed from Figures 3-5 that the lithium ion battery cathode material surface forms obvious crystal lattice stripes, and the interplanar spacing thereof is 0.359 nm, 0.495 nm and 0.361 nm respectively, which is matched with the (111) crystal face of Ca d ZrO 3-f , the (011) crystal face of La e Ca 2-e CoO 4-g and the (101) crystal face of La2Li m Ni 1-m O 4-g respectively.

[0077] Embodiment 2:

[0078] A lithium ion battery cathode material, comprising a cathode material matrix and a composite coating layer coated on the surface of the cathode material matrix, the composite coating layer comprises a perovskite oxide Sr 0.8 ZrO 2.8 , a perovskite-like oxide La 1.5 Sr 0.5 CoO 3.75 , La2Li 0.4 Ni 0.6 O 3.9 and LiCoO2, wherein the chemical formula of the cathode material matrix is Li 1.03 Ni 0.77 Co 0.05 Mn 0.18 Zr 0.002 W 0.0008 Sr0.0015 O2, the thickness of the coating layer is about 0.15 μm, the median particle size D50 of the lithium ion battery cathode material is about 3.55 μm, and the specific surface area is about 0.68 m 2 / g.

[0079] This example uses the same ternary cathode material matrix as Example 1, only in the preparation of the lithium ion battery cathode material in step (2), CaCO3 is replaced by SrO, and the molar amount of Sr added is the same as the molar amount of Ca used in Example 1, and it is calculated that the mass fraction of Sr added to the ternary cathode material matrix is 3280 ppm, and other preparation steps and conditions remain unchanged.

[0080] Example 3:

[0081] A lithium ion battery cathode material, comprising a cathode material matrix and a composite coating layer coated on the surface of the cathode material matrix, the composite coating layer comprising a perovskite-type oxide Ca 0.8 ZrO 2.8 , a perovskite-type oxide Pr 1.5 Ca 0.5 CoO 3.75 , La2Li 0.4 Ni 0.4 O 3.9 , and LiCoO2, wherein the chemical formula of the cathode material matrix is Li 1.03 Ni 0.77 Co 0.05 Mn 0.18 Zr 0.002 W 0.0008 Sr 0.0015 O2, the thickness of the coating layer is about 0.17 μm, the median particle size D50 of the lithium ion battery cathode material is about 3.45 μm, and the specific surface area is about 0.75 m 2 / g.

[0082] This example uses the same ternary cathode material matrix as Example 1, only in the preparation of the lithium ion battery cathode material in step (2), La2O3 is replaced by Pr6O 11 , and the molar amount of Pr added is the same as the molar amount of La used in Example 1, and it is calculated that the mass fraction of Pr added to the ternary cathode material matrix is 3045 ppm, and other preparation steps and conditions remain unchanged.

[0083] Example 4:

[0084] This example uses the same ternary cathode material matrix as Example 1, only in the preparation of the lithium ion battery cathode material in step (2), the concentration of oxygen introduced is adjusted to 40%, and other preparation steps and conditions remain unchanged.

[0085] Example 5:

[0086] This example uses the same ternary positive electrode material matrix as Example 1, only adjusting the concentration of oxygen introduced to 80% during the preparation of the lithium ion battery positive electrode material in Step (2), and keeping other preparation steps and conditions unchanged.

[0087] Example 6:

[0088] A lithium ion battery positive electrode material, comprising a positive electrode material matrix and a composite coating layer coated on the surface of the positive electrode material matrix, the composite coating layer comprising a perovskite-type oxide Ca 0.8 ZrO 2.8 , a perovskite-type oxide La 1.5 Ca 0.5 CoO 3.75 , La2Li 0.4 Ni 0.6 O 3.9 , and LiCoO2, wherein the chemical formula of the positive electrode material matrix is Li 1.03 Ni 0.77 Co 0.05 Mn 0.18 Zr 0.002 W 0.0008 Sr 0.0015 O2, the thickness of the coating layer is about 0.12 μm, the median particle size D50 of the lithium ion battery positive electrode material is about 3.4 μm, and the specific surface area is about 0.63 m 2 / g.

[0089] This example uses the same ternary positive electrode material matrix as Example 1, only adjusting the mass fraction of La element, Ca element, Zr element in La2O3, CaCO3, ZrO2 to 1500 ppm, 1000 ppm, 300 ppm, respectively, relative to the mass fraction of the ternary positive electrode material matrix during the preparation of the lithium ion battery positive electrode material in Step (2), and keeping other preparation steps and conditions unchanged.

[0090] Example 7:

[0091] A lithium ion battery positive electrode material, comprising a positive electrode material matrix and a composite coating layer coated on the surface of the positive electrode material matrix, the composite coating layer comprising a perovskite-type oxide Ca 0.8 ZrO 2.8 , a perovskite-type oxide La 1.5 Ca 0.5 CoO 3.75 , La2Li 0.4 Ni 0.6 O 3.9 , and LiCoO2, wherein the chemical formula of the positive electrode material matrix is Li 1.03 Ni0.77 Co 0.05 Mn 0.18 Zr 0.002 W 0.0008 Sr 0.0015 O2, the thickness of the coating layer is about 0.22 μm, the median particle size D50 of the lithium ion battery positive electrode material is about 3.65 μm, and the specific surface area is about 0.72 m 2 / g.

[0092] This example uses the same ternary positive electrode material substrate as Example 1, only the mass fraction of La element, Ca element, and Zr element in La2O3, CaCO3, and ZrO2 is adjusted to 4500 ppm, 4000 ppm, and 3000 ppm, respectively, in the preparation of the lithium ion battery positive electrode material in step (2), and other preparation steps and conditions remain unchanged.

[0093] Comparative Example 1:

[0094] The lithium ion battery positive electrode material of this comparative example includes a positive electrode material substrate and a LiCoO2 layer coated on the surface of the substrate, and the chemical formula of the positive electrode material substrate is Li 1.03 Ni 0.77 Co 0.05 Mn 0.18 Zr 0.002 W 0.0008 Sr 0.0015 O2, the thickness of the coating layer is about 0.11 μm, and the median particle size D50 of the lithium ion battery positive electrode material is about 3.3 μm.

[0095] This comparative example uses the same ternary positive electrode material substrate as Example 1, only Co(OH)2 is used as the coating source in the preparation of the lithium ion battery positive electrode material in step (2), and La2O3, CaCO3, and ZrO2 are not added, and other preparation steps and conditions remain unchanged.

[0096] Comparative Example 2:

[0097] The lithium ion battery positive electrode material of this comparative example includes a positive electrode material substrate and a perovskite-like oxide La 1.5 Ca 0.5 CoO 3.75 , La2Li 0.4 Ni 0.6 O 3.9 and a LiCoO2 layer coated on the surface of the substrate, and the chemical formula of the positive electrode material substrate is Li 1.03 Ni 0.77 Co 0.05 Mn 0.18 Zr 0.002 W 0.0008 Sr0.0015 O2, the thickness of the coating layer is about 0.14 μm, and the median particle size D50 of the lithium ion battery cathode material is about 3.4 μm.

[0098] The comparative example uses the same ternary cathode material matrix as in Example 1, only in the preparation of the lithium ion battery cathode material in step (2), the coating source uses Co(OH)2, La2O3, CaCO3, and no ZrO2 is added, and the other preparation steps and conditions remain unchanged.

[0099] Comparative Example 3:

[0100] The lithium ion battery cathode material of the comparative example includes a cathode material matrix and a perovskite oxide Ca 0.8 ZrO 2.8 and a LiCoO2 layer, the chemical formula of the cathode material matrix is Li 1.03 Ni 0.77 Co 0.05 Mn 0.18 Zr 0.002 W 0.0008 Sr 0.0015 O2, the thickness of the coating layer is about 0.12 μm, and the median particle size D50 of the lithium ion battery cathode material is about 3.45 μm.

[0101] The comparative example uses the same ternary cathode material matrix as in Example 1, only in the preparation of the lithium ion battery cathode material in step (2), the coating source uses Co(OH)2, CaCO3, ZrO2, and no La2O3 is added, and the other preparation steps and conditions remain unchanged.

[0102] Comparative Example 4:

[0103] The comparative example uses the same ternary cathode material matrix as in Example 1, only in the preparation of the lithium ion battery cathode material in step (2), the oxygen concentration of the oxygen gas introduced is adjusted to 25%, and the other preparation steps and conditions remain unchanged.

[0104] Comparative Example 5:

[0105] The comparative example uses the same ternary cathode material matrix as in Example 1, only in the preparation of the lithium ion battery cathode material in step (2), the oxygen concentration of the oxygen gas introduced is adjusted to 95%, and the other preparation steps and conditions remain unchanged.

[0106] The lithium ion battery cathode materials prepared in all the above examples and comparative examples are prepared into lithium ion battery cathodes, and are respectively prepared into button cells for electrical performance evaluation comparison. The model of the button cell is CR2032, the negative electrode uses lithium sheet, and the separator and electrolyte are purchased from the market.

[0107] The test conditions of the button cell are as follows: the charge-discharge voltage interval is 3.0-4.45 V; the specific capacity test is carried out at a charge-discharge rate of 0.1 C, the high-temperature cycle test is carried out at a charge-discharge rate of 1 C, and the cycle number is 50 cycles; the DCR test is carried out by discharging the battery at a rate of 0.2 C to a specific SOC, and then discharging at a rate of 1 C for 30 s, and the DCR value is calculated by dividing the voltage decay value by the current value in the time; the ambient temperature during the specific capacity and DCR tests is 25 DEG C, and the high-temperature cycle test temperature is 45 DEG C.

[0108] The results of the specific capacity, DCR at 10% SOC, and high-temperature cycle retention rate of the lithium ion batteries of all the examples and the comparative examples are shown in Table 1 below.

[0109] Table 1: Test results of the button cell performance

[0110] As can be seen from the test data in Table 1, in the technical solution provided in the present application, the oxygen concentration in the second sintering is controlled, so that the ternary positive electrode material with a composite coating layer can be prepared, the composite coating layer is composed of a perovskite type Y d ZrO 3-f , a perovskite type X e Y 2-e M2O 4-g , X2Li m M2 1-m O 4-n , and LiCoO2; under the high-voltage test system of 4.45 V, the lithium ion positive electrode material of the present application performs best in the specific capacity, initial DCR, and high-temperature cycle capacity retention rate, and the high-temperature cycle performance is improved significantly compared with the comparative examples. In Comparative Examples 1-3, the coating material is missing, and the performance of the ternary positive electrode material is overall inferior to that of Example 1; in Comparative Examples 4-5, the oxygen concentration is not suitable, which is not conducive to the growth of perovskite coating or the formation of oxygen vacancies, and the material performance is improved compared with Comparative Examples 1-3, but is not as good as that of Example 1.

[0111] The test results of the electrical performance of the lithium ion batteries of Example 1 and Comparative Example 1 are taken as typical examples for plotting and comparison, and the results of the first discharge, DCR, and high-temperature cycle retention rate are shown in Figures 6-8, respectively.

[0112] The button cell corresponding to Example 1 and Comparative Example 1 was charged to 4.45V, respectively, the battery was disassembled, and the positive plate was cleaned and dried using DMC, 0.2 μL of electrolyte was added dropwise, and the thermal decomposition curve was tested using a differential scanning calorimeter with a heating rate of 10 ℃ / min. The thermal decomposition curve corresponding to 4.45V high voltage was obtained, as shown in Figure 9. As shown in Figure 9, the lithium ion battery of Example 1 has significantly improved thermal stability: the initial temperature and peak temperature of the lithium ion battery reaction are 177.6 ℃ and 220.1 ℃, respectively, which are significantly delayed compared with the initial temperature of 167.5 ℃ and the peak temperature of 215.0 ℃ of Comparative Example 1, and the peak heat flow of the reaction is also significantly reduced.

[0113] The positive electrode materials prepared from the lithium ion battery positive electrode materials of Example 1 and Comparative Example 1 were prepared into positive electrodes, and soft pack batteries were prepared for gas production performance evaluation comparison. The capacity of the soft pack battery was designed to be 1.65 Ah, the negative electrode used graphite, the separator, electrolyte, binder and conductive agent were all purchased from the market. The soft pack battery was made by winding process, and went through the processes of liquid injection, formation, degassing, heat sealing, etc. The test conditions of the gas production performance of the soft pack battery were as follows: using 0.33C charging rate to charge the battery to 4.45V, and placing the battery in a 60℃ incubator, using the drainage method to test the gas production at different time points (1 / 2 / 3 / 4 weeks), and dividing the result by the mass of the corresponding soft pack battery positive electrode material to obtain the gas production per unit mass, the results are shown in Figure 10. As shown in Figure 10, at the 4th week, the gas production per unit mass of the lithium ion battery positive electrode material in Example 1 was 0.24 mL / g, which was much lower than 0.39 mL / g in Comparative Example 1, and the gas production performance was significantly improved.

[0114] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0115] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be construed as limiting the scope of the patent application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of the patent of the present application should be subject to the appended claims.

Claims

1. A lithium ion battery cathode material, comprising a cathode material substrate and a composite coating layer coated on the surface of the cathode material substrate, wherein the composite coating layer comprises a perovskite oxide, a perovskite-like oxide and LiCoO 2.

2. The lithium-ion battery cathode material of claim 1, wherein, The perovskite-type oxide includes an ABO3-type perovskite oxide having oxygen vacancies, which has a chemical formula of Y d ZrO 3-f wherein Y is one or both of Ca and Sr, 0.5≤d<1, and 0 f≤0.

5.

3. The lithium-ion battery cathode material of claim 1 or 2, wherein, The perovskite-type oxide includes a perovskite-type oxide of A2BO4 type having oxygen vacancies, and has a chemical formula of X e Y 2-e M2O 4-g wherein X is at least one of La, Ce, Pr, Gd, Yb, Y is one or both of Ca and Sr, M2 is one or both of Ni and Co, 1≤e<2, and 0g≤0.

5.

4. The lithium-ion battery cathode material of claim 3, wherein, The perovskite-like oxide further comprises X2Li m M2 1-m O 4-n wherein 0 < m < 0.5, 0 < n < 0.

5.

5. The lithium-ion battery cathode material of any one of claims 1-4, wherein, The thickness of the composite coating layer is 0.03 μm to 0.3 μm.

6. The lithium-ion battery cathode material of any one of claims 1-5, wherein, The median particle size D50 of the lithium ion battery cathode material is 2-5 μm, and the specific surface area is 0.5-1.2 m 2 / g. 2 / g.

7. The lithium-ion battery cathode material of any one of claims 1-6, wherein, The chemical formula of the positive electrode material base is Li 1+a Ni x Co y Mn 1-x-y-b M1 b O z , wherein M1 is a doping element, selected from at least two of Zr, Al, Co, W, Nb, Y and Sr, 0.5≤x≤0.95, 0.05≤y≤0.2, 0≤a≤0.2, 0 b≤0.1, 0.05≤1-x-y-b≤0.4, 1.8 z 2.

2. 8.A method for preparing the lithium ion battery cathode material according to any one of claims 1 to 7, comprising: mixing the cathode material substrate, a cobalt source, a zirconium source, an X-containing coating agent and a Y-containing coating agent, and high-temperature sintering to obtain the lithium ion battery cathode material, wherein the high-temperature sintering is performed at a temperature of 600 ℃ to 900 ℃ for 4 h to 12 h in an atmosphere with an oxygen concentration of 40% to 80%.

9. The production method according to claim 8, wherein The cobalt source is selected from one or more of cobaltous hydroxide, cobalt hydroxide oxide, cobalt oxide, cobalt sulfate and cobalt acetate; wherein the mass fraction of Co in the cobalt source relative to the cathode material substrate is 3500 ppm to 35000 ppm.

10. The production method according to claim 8 or 9, wherein The zirconium source is selected from one or both of zirconium oxide and zirconium sulfate; wherein the mass fraction of Zr in the zirconium source relative to the cathode material substrate is 300 ppm to 3000 ppm.

11. The production method according to any one of claims 8 to 10, wherein The X-containing coating agent is selected from one or more of oxides, hydroxides, chlorides, carbonates and nitrates containing element X; wherein the mass fraction of X in the X-containing coating agent relative to the cathode material substrate is 1500 ppm to 4500 ppm.

12. The production method according to any one of claims 8 to 11, wherein The Y-containing coating agent is selected from one or more of oxides, hydroxides, chlorides, carbonates and nitrates containing element Y; wherein the mass fraction of Y in the Y-containing coating agent relative to the cathode material substrate is 1000 ppm to 4000 ppm.

13. The production method according to any one of claims 8 to 12, wherein The cathode material substrate is obtained by mixing a ternary hydroxide precursor, a lithium source and a M1-containing dopant and then sintering, wherein the lithium source is selected from one or more of lithium hydroxide, lithium carbonate, lithium fluoride and lithium acetate, the molar ratio of the lithium source to the ternary hydroxide precursor is 1.01 to 1.11, the mass fraction of M1 in the M1-containing dopant relative to the ternary hydroxide precursor is 1000 ppm to 8000 ppm, the sintering is performed at a temperature of 700 ℃ to 1100 ℃ for 8 h to 16 h in an oxygen atmosphere with an oxygen concentration of greater than 95%.

14. A lithium-ion battery, wherein, The cathode material in the lithium ion battery is the lithium ion battery cathode material according to any one of claims 1 to 7 or is prepared by the method according to any one of claims 8 to 13. 15.An electric device comprising the lithium ion battery according to claim 14.

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