Positive electrode active material, preparation method thereof and battery

Abstract

The invention discloses a positive electrode active material, a preparation method thereof and a battery, based on the total content of transition metal elements in the positive electrode active material, the molar content of a nickel element is greater than 85%; and the unit cell volume expansion rate of the positive electrode active material is 5.0%-1.0%. Therefore, the volume shrinkage reversibility of the positive electrode active material is relatively good, fatigue and fracture of a crystal structure are not easily caused in a lithium intercalation and deintercalation process, and the capacity exerting and cycling stability of the positive electrode active material is favorably improved.

Description

Technical Field

[0001] This application relates to the field of lithium battery technology, specifically to positive electrode active materials and their preparation methods, and batteries. Background Technology

[0002] New energy vehicles, as a strategic emerging industry, are a new pillar and a new track leading economic and technological development, and a strategic measure to address climate change and promote green development. The key to the continued rapid development of new energy vehicles depends on breakthroughs in power batteries and key materials. As the core material of power batteries, cathode active materials play a decisive role in the energy density, lifespan, and safety of the battery. High-nickel ternary cathode active materials (LiNi...) x Co y Mn 1-x-y O2 (x≥0.8) has become a research hotspot due to its high specific capacity. However, when the nickel content is further increased, the material faces problems of structural instability and poor thermal stability, resulting in severe gas generation during cycling and causing significant battery capacity decay.

[0003] Therefore, the stability of high-nickel ternary cathode active materials still needs further improvement.

[0004] It should be noted that the above statements are only used to provide background information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0005] In a first aspect of this application, a positive electrode active material is proposed, wherein, based on the total content of transition metal elements in the positive electrode active material, the molar content of nickel is greater than 85%; the cell volume expansion rate of the positive electrode active material is... 5.0% ~ 1.0%. As a result, the volume shrinkage of the positive electrode active material is reversible, and it is not easy to cause crystal structure fatigue and cracking during the lithium insertion / extraction process, which is conducive to improving the capacity utilization and cycle stability of the positive electrode active material.

[0006] In some embodiments, the cell volume expansion rate of the positive electrode active material is 4.0% ~ 1.5%. This is beneficial for further improving the structural stability of the positive electrode active material.

[0007] In some embodiments, the effective yield strength of the positive electrode active material is 1.0 GPa to 4.0 GPa. Therefore, the positive electrode active material is less prone to plastic deformation, particle cracking, or pulverization during cycling, exhibiting high structural integrity.

[0008] In some embodiments, the positive electrode active material includes a matrix; the matrix includes a first region, a second region, and a third region distributed radially along the matrix, the second region surrounding the first region, and the third region surrounding the second region; radially along the matrix, the content of element M1 at the boundary of the first region is greater than the content of element M1 at the center of the first region, and element M1 includes at least one of W, Mo, Nb, and Ta; radially along the matrix, the second region includes a plurality of spaced-apart aggregation regions of element M2, and element M2 includes at least one of Mg, La, Al, Sr, Ba, Y, Zr, Ca, Fe, Zn, Sn, W, V, Mo, Sb, Ta, Ti, Nb, S, P, and B; the third region includes element Q, and element Q includes at least two of Mg, La, Al, Sr, Ba, Y, Zr, Ca, Fe, Zn, Sn, W, V, Mo, Sb, Ta, Ti, Nb, S, P, and B. Therefore, the positive electrode active material has high thermal stability and produces less gas during cycling, which is beneficial to improving the cycle performance of the battery.

[0009] In some embodiments, the thickness of the first region in the radial direction of the substrate is 0.5 μm to 3.5 μm; and / or, the thickness of the second region in the radial direction of the substrate is 1.0 μm to 3.0 μm; and / or, the thickness of the third region in the radial direction of the substrate is 1.0 μm to 3.0 μm. This is beneficial for further improving the structural stability of the positive electrode active material.

[0010] In some embodiments, the spacing between adjacent M2 element aggregation regions is 1.0 μm to 3.0 μm. This is beneficial for reducing M... 2 The aggregation of elements helps stabilize the crystal lattice structure and suppress the occurrence of unfavorable phase transitions.

[0011] In some embodiments, the Q element is uniformly distributed in the third region. This is beneficial for further stabilizing the crystal structure of the positive electrode active material.

[0012] In some embodiments, the matrix satisfies formula I: Li 1-δ (Ni a Co b Mn c Al d ) 1-k-q M k Q q O2 type I; Wherein, -0.05≤δ≤0.05, a>0.85, a+b+c+d=1, 0.01≤k≤0.05, 0.01≤q≤0.05; M includes elements M1 and M2. Element M1 includes at least one of W, Mo, Nb, and Ta. Element M2 includes at least two of Mg, La, Al, Sr, Ba, Y, Zr, Ca, Fe, Zn, Sn, W, V, Mo, Sb, Ta, Ti, Nb, S, P, and B. Element Q includes at least two of Mg, La, Al, Sr, Ba, Y, Zr, Ca, Fe, Zn, Sn, W, V, Mo, Sb, Ta, Ti, Nb, S, P, and B. Therefore, doping with elements M and Q helps improve the structural stability of the positive electrode active material and suppresses the generation and propagation of microcracks during cycling.

[0013] In some embodiments, the positive electrode active material further includes a coating layer comprising at least one of Al₂O₃, ZrO₂, LiPO₃, LiAlO₂, LLZO, LATP, Li₃PO₄, and LiNbO₃. Thus, the coating layer can provide a physical buffer, improve the lithium-ion transport rate, and help construct a robust and highly lithium-conducting cathode electrolyte interface (CEI), reducing transition metal ion dissolution and interfacial side reactions.

[0014] In some embodiments, the primary particle size of the positive electrode active material is 200 nm to 500 nm; and / or, the grain size of the positive electrode active material is 60 nm to 140 nm. This is beneficial for shortening the lithium-ion diffusion distance and improving the rate performance of the positive electrode active material.

[0015] In some embodiments, the D of the positive electrode active material 50 The thickness is 9.5 μm to 18.5 μm; and / or, the SPAN of the positive electrode active material is 0.15 to 0.55; wherein, SPAN = (D 90 -D 10 ) / D 50 As a result, the particles of different sizes in the positive electrode active material are in a close-packed state, and the compaction density is significantly improved. This is beneficial to improving the uniformity and flatness of the positive electrode sheet, thereby reducing local stress concentration, avoiding excessive particle breakage and pulverization, and reducing the occurrence of side reactions.

[0016] In a second aspect, this application proposes a method for preparing the aforementioned positive electrode active material, comprising: mixing a nickel source, a manganese source, a cobalt source, an aluminum source, a precipitant, and a complexing agent to obtain a mixed solution; adding an M1 source to the mixed solution to obtain an intermediate; adding an M2 source to the intermediate and performing co-precipitation to obtain a hydroxide precursor; mixing the hydroxide precursor, a lithium source, and a Q source and then performing a first sintering treatment to obtain a matrix, thereby obtaining the positive electrode active material. Thus, this application obtains a positive electrode active material with high structural stability through elemental doping, and the preparation method is simple, easy to operate, and readily applicable to industrial production.

[0017] In some embodiments, adding the M2 source to the intermediate includes multiple addition operations, with an interval of 1 to 5 hours between adjacent addition operations. This facilitates the formation of multiple M2 element aggregation regions with intervals.

[0018] In some embodiments, the mass percentage of element M1 in the hydroxide precursor is 2% to 5%; and / or, the mass percentage of element M2 in the hydroxide precursor is 1% to 5%. This is beneficial for improving the overall stability of the positive electrode active material.

[0019] In some embodiments, the heating rate of the first sintering treatment is 1℃ / min to 4℃ / min, the temperature is 720℃ to 790℃, and the time is 8h to 18h. This facilitates achieving a specific elemental distribution, optimizing grain growth, making lithium-ion transport channels more unobstructed, and improving rate performance.

[0020] In some embodiments, the method further includes: mixing the substrate and the coating material and then performing a second sintering treatment, wherein the temperature of the second sintering treatment is 250℃~450℃ and the time is 4h~12h. This facilitates the full diffusion of metal elements in the coating layer, achieving a uniform distribution.

[0021] In some embodiments, the nickel source includes at least one of nickel sulfate, nickel nitrate, nickel chloride, and nickel acetate; and / or, the cobalt source includes at least one of cobalt sulfate, cobalt nitrate, cobalt chloride, and cobalt acetate; and / or, the manganese source includes at least one of manganese sulfate, manganese carbonate, manganese nitrate, and manganese tetroxide; and / or, the aluminum source includes at least one of aluminum hydroxide, aluminum oxide, and aluminum sulfate; and / or, the lithium source includes at least one of lithium hydroxide, lithium hydroxide monohydrate, lithium nitrate, lithium carbonate, and lithium acetate. Therefore, the raw materials are widely available, the cost is low, and large-scale promotion is convenient.

[0022] In some embodiments, the M1 source includes at least one of the following: oxide, hydroxide, carbonate, fluoride, sulfate, phosphate, and chloride corresponding to the M1 element. This facilitates the formation of a first region with a gradient distribution of the M1 element.

[0023] In some embodiments, the M2 source includes at least one of the oxides, hydroxides, carbonates, fluorides, sulfates, phosphates, and chlorides corresponding to the M2 element. This facilitates the formation of a second region where the M2 element is periodically spaced.

[0024] In some embodiments, the Q source includes at least one of the following: oxide, hydroxide, carbonate, fluoride, sulfate, phosphate, and chloride corresponding to the Q element. This facilitates the formation of a third region with a uniform distribution of the Q element.

[0025] In a third aspect, this application proposes a battery comprising a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive active material layer located on at least one side of the positive current collector, the positive active material layer comprising the positive active material described in the first aspect of this application or a positive active material prepared using the method described in the second aspect of this application. Therefore, this battery exhibits high cycle stability at high temperatures. Attached Figure Description

[0026] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, wherein, Figure 1 This is a cross-sectional SEM image of a hydroxide precursor according to an embodiment of this application; Figure 2 This is a cross-sectional SEM image of the positive electrode active material according to an embodiment of this application; Figure 3 Here is a SEM image of the positive electrode active material according to an embodiment of this application; Figure 4 This is a cross-sectional SEM image of the positive electrode active material according to an embodiment of this application; Figure 5 This is an elemental distribution diagram of the positive electrode active material according to an embodiment of this application; Figure 6 This is an XRD pattern of a positive electrode active material according to an embodiment of this application. Detailed Implementation

[0027] The embodiments of this application are described in detail below, with examples of these embodiments shown in the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0028] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0029] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are open-ended expressions, meaning they include what is specified in this application but do not exclude other aspects.

[0030] In the description of this application, all figures disclosed herein, whether or not the words "approximately" or "about" are used, are approximate values. Each figure may vary by less than 10% or by a difference that is considered reasonable by one of the art, such as 1%, 2%, 3%, 4%, or 5%.

[0031] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0032] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. "First feature" and "second feature" may include one or more of the indicated feature.

[0033] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0034] In this application, the order in which the steps are written does not imply a strict execution order and does not limit the implementation process. The specific execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps in this application can be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0035] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0036] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0037] High-nickel cathode active materials are prone to the H2→H3 phase transition in the delithiation state, leading to lattice collapse and oxygen release. During cycling, transition metal ions dissolve and react with the electrolyte to generate gases such as CO2 and HF, causing battery expansion. In addition, high-nickel cathode active materials have a high residual alkali content on the surface, which easily triggers interfacial side reactions, resulting in rapid capacity decay and a short cycle life.

[0038] In a first aspect of this application, a positive electrode active material is proposed, wherein, based on the total content of transition metal elements in the positive electrode active material, the molar content of nickel is greater than 85%; the cell volume expansion rate of the positive electrode active material is... 5.0% ~ 1.0%.

[0039] As an example, the cell volume expansion rate of the positive electrode active material can be... 5.0%, 4.0%, 3.0% 2.0% or 1.0%, etc.

[0040] When the cell volume expansion rate is within the above range, the volume shrinkage reversibility of the positive electrode active material is good, and it is not easy to cause crystal structure fatigue and cracking during the lithium insertion / extraction process, which is conducive to improving the capacity utilization and cycle stability of the positive electrode active material.

[0041] As an example, specific test methods for cell volume expansion rate include: (1) The initial cell parameters a and c of the positive electrode active material were obtained through Rietveld refinement. The initial state unit cell volume V is obtained. initial ; (2) The prepared positive electrode active material was used to fabricate the electrode, and a half-cell was assembled. The electrode was charged to 4.3V (fully delithiated state), the half-cell was disassembled, the positive electrode active material was removed, and the material was cleaned with dimethyl carbonate (DMC) and XRD patterns were collected. The charged state cell parameters a and c were obtained through Rietveld refinement. The charged state unit cell volume V is obtained. Charged ; (3) According to ΔV max = (V charged -V initial ) / V initial ×100% yields the cell volume expansion rate.

[0042] In some embodiments, the cell volume expansion rate of the positive electrode active material is 4.0% ~ 1.5%. This is beneficial for further improving the structural stability of the positive electrode active material.

[0043] In some embodiments, the effective yield strength of the positive electrode active material is 1.0 GPa to 4.0 GPa.

[0044] As an example, the effective yield strength of the positive electrode active material can be 1.0 GPa, 1.5 GPa, 2.0 GPa, 2.5 GPa, 3.0 GPa, 3.5 GPa, or 4.0 GPa, etc.

[0045] When the effective yield strength is within the above range, the positive electrode active material is not prone to plastic deformation, particle cracking or pulverization during cycling, and has high structural integrity.

[0046] As an example, specific test methods for effective yield strength include: (1) Nanoindentation tests were performed on a large number of positive electrode active material particles to obtain accurate load-depth curves. The hardness (H) of the positive electrode active material was calculated using the Oliver-Pharr method. H=P max / A c ; Among them, P max The maximum load measured by nanoindentation, A c It is the projected contact area under maximum load. For an ideal Glass indenter, A c = 24.56 h c 2 Contact depth hc It is the vertical distance between the tip of the indenter and the initial contact point on the surface of the positive electrode active material under maximum load.

[0047] (2) Effective yield strength σ y eff ≈H / 3, where 3 is the constraint factor.

[0048] In some embodiments, the positive electrode active material includes a matrix; see reference. Figure 4 and Figure 5 The matrix includes a first region, a second region, and a third region distributed radially along the matrix, with the second region surrounding the first region and the third region surrounding the second region. Radially along the matrix, the content of element M1 at the boundary of the first region is greater than the content of element M1 at the center of the first region, and element M1 includes at least one of W, Mo, Nb, and Ta. Radially along the matrix, the second region includes multiple spaced-apart aggregation zones of element M2, and element M2 includes at least one of Mg, La, Al, Sr, Ba, Y, Zr, Ca, Fe, Zn, Sn, W, V, Mo, Sb, Ta, Ti, Nb, S, P, and B. The third region includes element Q, and element Q includes at least two of Mg, La, Al, Sr, Ba, Y, Zr, Ca, Fe, Zn, Sn, W, V, Mo, Sb, Ta, Ti, Nb, S, P, and B. In the first region, the gradient distribution of M1 elements helps to strengthen the core structure of the positive electrode active material, suppress ion mixing, and improve intrinsic stability. In the second region, the periodic distribution of M2 elements can effectively suppress the collapse and phase transformation of the layered structure and improve the stability of the crystal structure. At the same time, the spacing of the M2 element aggregation regions results in a small amount of M2 element doping, which improves structural stability while having a small impact on capacity. In the third region, the doping of Q elements helps to stabilize the crystal structure, jointly suppress the generation and propagation of microcracks, and improve cycle performance.

[0049] In some embodiments, refer to Figure 4 In the radial direction of the substrate, the thickness I of the first region is 0.5 μm to 3.5 μm; and / or, in the radial direction of the substrate, the thickness II of the second region is 1.0 μm to 3.0 μm; and / or, in the radial direction of the substrate, the thickness III of the third region is 1.0 μm to 3.0 μm. This is beneficial for further improving the structural stability of the positive electrode active material.

[0050] As an example, the thickness of the first region can be 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm, 3.0μm, or 3.5μm, etc.; the thickness of the second region can be 1μm, 1.5μm, 2μm, 2.5μm, or 3.0μm, etc.; and the thickness of the third region can be 1μm, 1.5μm, 2μm, 2.5μm, or 3.0μm, etc.

[0051] As an example, the thickness testing method for the first, second, and third regions is as follows: Using the SEM profile testing method, the micron-sized particle sample is first embedded and cured in resin, and then ion-cut to obtain a smooth profile. The profile is observed using a scanning electron microscope at an accelerating voltage of 5kV~20kV, and target particle size images containing clear particle cross-sections are acquired. Finally, image analysis software is used to measure the thickness of different regions of the particle cross-section manually or semi-automatically based on an image scale.

[0052] As an example, the method for testing the content of element M1 in the first region is as follows: Elemental distribution and content analysis of the sample is performed using a scanning electron microscope equipped with an EDS detector. Under conditions of 10 kV accelerating voltage and 10 mm working distance, a surface scan analysis is performed on a selected area of ​​the sample surface, acquiring characteristic X-ray signals. Using a standard-free quantitative analysis method, background subtraction and overlapping peak resolution are performed on the spectral peaks using a ZAF correction model to obtain the weight percentage content of each element and generate a pseudo-color elemental distribution map. For point analysis, 60 seconds of data are acquired at each location to ensure sufficient counting statistics, and a 100 nm step size is used for line scanning to obtain elemental concentration change curves.

[0053] In some embodiments, the spacing between adjacent M2 element aggregation regions is 0.2 μm to 1.0 μm, for example, it can be 0.2 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.8 μm, or 1.0 μm. This helps reduce the aggregation of M2 elements, contributes to stabilizing the crystal structure, and suppresses undesirable phase transitions.

[0054] In some embodiments, the Q element is uniformly distributed in the third region. This is beneficial for further stabilizing the crystal structure of the positive electrode active material.

[0055] In some embodiments, the matrix satisfies formula I: Li 1-δ (Ni a Co b Mn c Al d ) 1-k-q M k Q q O2 type I; Wherein, -0.05≤δ≤0.05, a>0.85, a+b+c+d=1, 0.01≤k≤0.05, 0.01≤q≤0.05; M includes elements M1 and M2. Element M1 includes at least one of W, Mo, Nb, and Ta. Element M2 includes at least two of Mg, La, Al, Sr, Ba, Y, Zr, Ca, Fe, Zn, Sn, W, V, Mo, Sb, Ta, Ti, Nb, S, P, and B. Element Q includes at least two of Mg, La, Al, Sr, Ba, Y, Zr, Ca, Fe, Zn, Sn, W, V, Mo, Sb, Ta, Ti, Nb, S, P, and B. Therefore, doping with elements M and Q helps improve the structural stability of the positive electrode active material and suppresses the generation and propagation of microcracks during cycling.

[0056] As an example, δ can be -0.05, -0.04, -0.03, -0.02, -0.01, 0, 0.01, 0.02, 0.03, 0.04, or 0.05, etc.; a can be 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, or 0.92, etc.; k can be 0.01, 0.02, 0.03, 0.04, or 0.05, etc.; q can be 0.01, 0.02, 0.03, 0.04, or 0.05, etc.

[0057] In some embodiments, the positive electrode active material further includes a coating layer comprising at least one of Al₂O₃, ZrO₂, LiPO₃, LiAlO₂, LLZO, LATP, Li₃PO₄, and LiNbO₃. Thus, the coating layer can provide a physical buffer, improve the lithium-ion transport rate, and help construct a robust and highly lithium-conducting cathode electrolyte interface (CEI), reducing transition metal ion dissolution and interfacial side reactions.

[0058] In some embodiments, the primary particle size of the positive electrode active material is 200 nm to 500 nm; and / or, the grain size of the positive electrode active material is 60 nm to 140 nm. The positive electrode active material includes secondary particles, which are formed by the aggregation of primary particles.

[0059] As an example, the primary particle size of the positive electrode active material can be 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, or 500nm, etc.

[0060] As an example, the grain size of the positive electrode active material can be 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm or 140nm, etc.

[0061] This helps to shorten the lithium-ion diffusion distance and improve the rate performance of the positive electrode active material.

[0062] As an example, the primary particle size was obtained by testing with a Hitachi S-4800 scanning electron microscope from Japan. The primary particles were measured in five 30k images, and the average of approximately 150 results was taken.

[0063] As an example, the grain size was obtained using a Smart Lab 9kW XRD instrument from Rigaku Corporation, Japan. Quantitative analysis of the Dxrd-size and cell volume was achieved by finely fitting the theoretical diffraction intensity line spectrum with the measured XRD intensity line spectrum, using whole-powder pattern fitting. The test target was Cu, and analysis was performed under Cu Kα radiation. The instrument's tube voltage was set to 40 kV, the tube current to 200 mA, the sample test angle range was 5° to 120°, the scan rate was 1° / min, and the scan step size was 0.02°.

[0064] In some embodiments, the cell volume expansion rate of the positive electrode active material is 5.0% ~ 1.0%.

[0065] In some embodiments, the D of the positive electrode active material 50 The thickness is 9.5 μm to 18.5 μm; and / or, the SPAN of the positive electrode active material is 0.15 to 0.55; wherein, SPAN = (D 90 -D 10 ) / D 50 .

[0066] As an example, the D of the positive electrode active material 50 It can be 9.5μm, 10.5μm, 11.5μm, 12.5μm, 13.5μm, 14.5μm, 15.5μm, 16.5μm, 17.5μm or 18.5μm, etc.

[0067] As an example, the SPAN of the positive electrode active material can be 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, or 0.55, etc.

[0068] As a result, the particles of different sizes in the positive electrode active material are in a close-packed state, and the compaction density is significantly improved. This is beneficial to improving the uniformity and flatness of the positive electrode sheet, thereby reducing local stress concentration, avoiding excessive particle breakage and pulverization, and reducing the occurrence of side reactions.

[0069] In particle size distribution, D 50Also known as the median particle size, it means that 50% of the volume of particles are smaller than or equal to this value, D. 90 This means that 90% of the volumetric particle size is less than or equal to this value, D 10 This means that 10% of the volume of particles are smaller than or equal to this value. (D) 10 D 50 D 90 It can be measured using a Marvern Hydro 2000mu laser particle size analyzer.

[0070] In a second aspect, this application proposes a method for preparing the aforementioned positive electrode active material. By doping with M and Q elements, a positive electrode active material with a small cell volume expansion rate is obtained. The preparation method is simple, easy to operate, and readily applicable to industrial production. Specifically, the method includes: S1: Mix the nickel source, manganese source, cobalt source, aluminum source, precipitant, and complexing agent to obtain a mixed solution.

[0071] In some embodiments, the nickel source includes at least one of nickel sulfate, nickel nitrate, nickel chloride, and nickel acetate; and / or, the cobalt source includes at least one of cobalt sulfate, cobalt nitrate, cobalt chloride, and cobalt acetate; and / or, the manganese source includes at least one of manganese sulfate, manganese carbonate, manganese nitrate, and manganese tetroxide; and / or, the lithium source includes at least one of lithium hydroxide, lithium hydroxide monohydrate, lithium nitrate, lithium carbonate, and lithium acetate; and / or, the aluminum source includes at least one of aluminum hydroxide, alumina, and aluminum sulfate. Therefore, the raw materials are widely available, the cost is low, and large-scale promotion is convenient.

[0072] In some embodiments, the precipitant may be a sodium hydroxide or lithium hydroxide solution; the complexing agent may be ammonia.

[0073] S2: Add source M1 to the mixed solution to obtain an intermediate.

[0074] In some embodiments, the M1 source includes at least one of the following: oxide, hydroxide, carbonate, fluoride, sulfate, phosphate, and chloride corresponding to the M1 element. This facilitates the formation of a first region with a gradient distribution of the M1 element.

[0075] In some embodiments, the mass percentage of M1 element in the hydroxide precursor is 2% to 5%, for example, it can be 2%, 3%, 4%, or 5%. This is beneficial for improving the intrinsic stability of the positive electrode active material.

[0076] As an example, a peristaltic pump can be used to gradually add the M1 source to the above mixed solution. By precisely controlling the feed rate of the M1 source, a gradient distribution of the M1 element content gradually increases from the inside to the outside during the growth process of the nickel-cobalt-manganese precursor from the core to the shell. This part is the first region, which serves as the core of the positive electrode active material.

[0077] S3: Add M2 source to the intermediate and co-precipitate to obtain hydroxide precursor.

[0078] In some embodiments, the M2 source includes at least one of the following: oxides, hydroxides, carbonates, fluorides, sulfates, phosphates, and chlorides corresponding to the M2 element. This facilitates the formation of a second region where the M2 element is periodically distributed.

[0079] In some embodiments, the mass percentage of M2 element in the hydroxide precursor is 1% to 5%, for example, it can be 1%, 2%, 3%, 4%, or 5%. This is beneficial for improving the overall stability of the positive electrode active material.

[0080] In some embodiments, adding the M2 source to the intermediate includes multiple addition operations, with an interval of 1h to 5h between adjacent addition operations, such as 1h, 2h, 3h, 4h, or 5h. This facilitates the formation of multiple M2 element aggregation regions with intervals.

[0081] As an example, the M2 source can be added to the above intermediate in batches at 3h, 5h, 7h, and 9h to carry out a co-precipitation reaction, so as to form a second region with M2 element aggregation zones spaced apart.

[0082] S4: The hydroxide precursor, lithium source, and Q source are mixed and subjected to a first sintering treatment to obtain a matrix, thereby obtaining the positive electrode active material.

[0083] In some embodiments, the Q source includes at least one of the following: oxide, hydroxide, carbonate, fluoride, sulfate, phosphate, and chloride corresponding to the Q element. This facilitates the formation of a third region with a uniform distribution of the Q element.

[0084] In some embodiments, the heating rate of the first sintering treatment is 1℃ / min to 4℃ / min, the temperature is 720℃ to 790℃, and the time is 8h to 18h. This facilitates achieving a specific elemental distribution, optimizing grain growth, making lithium-ion transport channels more unobstructed, and improving rate performance.

[0085] As an example, the heating rate of the first sintering treatment can be 1℃ / min, 2℃ / min, 3℃ / min or 4℃ / min, etc., the temperature can be 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, 780℃ or 790℃, etc., and the time can be 8h, 10h, 12h, 14h, 16h or 18h, etc.

[0086] In some embodiments, the method further includes: mixing the substrate with the coating material and then performing a second sintering treatment to obtain the positive electrode active material.

[0087] In some embodiments, the temperature of the second sintering treatment is 250°C to 450°C, and the time is 4 hours to 12 hours. This facilitates the full diffusion of metal elements in the coating layer, achieving a uniform distribution.

[0088] As an example, the temperature of the second sintering treatment can be 250℃, 300℃, 350℃, 400℃ or 450℃, etc., and the time can be 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h or 12h, etc.

[0089] As an example, the preparation method of the coating material may include: mixing triethyl phosphate ((C2H5O)3PO4) and LiOH in ethanol or isopropanol, controlling the pH value to 11~14, separating the solid and liquid, and then treating at 250℃~450℃ for 4h~12h to prepare 5nm~10nm LiPO3.

[0090] In a third aspect, this application proposes a battery comprising a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive active material layer located on at least one side of the positive current collector, the positive active material layer comprising the positive active material described in the first aspect of this application or a positive active material prepared using the method described in the second aspect of this application. Therefore, this battery exhibits high cycle stability at high temperatures.

[0091] The description of the various embodiments above tends to emphasize the differences between the various embodiments. The similarities or similarities between them can be referred to, and for the sake of brevity, they will not be repeated here.

[0092] The following specific embodiments illustrate the solution of this application. It should be noted that these embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0093] Example 1 (1) A 1 mol / L mixed salt solution was prepared by mixing NiSO4·6H2O (92 mol%), CoSO4·7H2O (4 mol%), MnSO4·H2O (3.5 mol%), and Al2(SO4)3 (0.5 mol%). 2 mol / L NaOH solution and 0.5 mol / L NH3·H2O were added to a continuously stirred reactor, maintaining the pH at 10.5 ± 0.2 and the temperature at 55 °C. Starting from the second hour of reaction, Na2WO4 (0.5 mol%) was gradually added using a peristaltic pump. At 3, 5, 7, and 9 hours, a mixed solution of TiO(NO3)2·xH2O and Mg(NO3)2 (0.3 mol%) was added. After 15 hours of reaction, the mixture was filtered, washed, and dried at 80 °C for 12 hours to obtain a gradient-doped hydroxide precursor.

[0094] (2) The precursor and LiOH·H2O were mixed at a molar ratio of Li / (Ni+Co+Mn+Al+Zr+Mg)=1.06, and Nb2O5 (0.5mol%) and Al2O3 (0.5mol%) were added at the same time. The first sintering treatment was carried out under an oxygen atmosphere. The temperature was increased to 450℃ at 5℃ / min and sintered for 3h. Then the temperature was increased to 780℃ and sintered for 12h. The mixture was naturally cooled to room temperature and crushed through a 400-mesh sieve to obtain the matrix.

[0095] (3) The matrix after the first sintering treatment is dispersed in LiPO3 sol (phosphoric acid and lithium hydroxide molar ratio 1:1), dried and then subjected to a second sintering treatment. The temperature of the second sintering treatment is 550℃ and the time is 5h to obtain the positive electrode active material.

[0096] Example 2 (1) A 1 mol / L mixed salt solution was prepared by mixing NiSO4·6H2O (92 mol%), CoSO4·7H2O (4 mol%), MnSO4·H2O (3.5 mol%), and Al2(SO4)3 (0.5 mol%). 2 mol / L NaOH solution and 0.5 mol / L NH3·H2O were added to a continuously stirred reactor, maintaining the pH at 10.5 ± 0.2 and the temperature at 55 °C. Starting from the 2nd hour of reaction, Na2WO4 (0.5 mol%) was gradually added using a peristaltic pump. Mg(NO3)2 solution (0.3 mol%) was added at 3 and 5 hours, and TiO(NO3)2·xH2O solution (0.3 mol%) was added at 7 and 9 hours. After 15 hours of reaction, the mixture was filtered, washed, and dried at 80 °C for 12 hours to obtain a gradient-doped hydroxide precursor.

[0097] (2) Same as Example 1.

[0098] (3) Same as Example 1.

[0099] Example 3 (1) Same as Example 1.

[0100] (2) Same as Example 1.

[0101] (3) The matrix after the first sintering treatment is dispersed in Li3PO4 suspension (prepared by ball milling with LiOH, H3PO4 and deionized water), dried and then subjected to a second sintering treatment. The temperature of the second sintering treatment is 550℃ and the time is 5h to obtain the positive electrode active material.

[0102] Example 18 The difference from Example 1 is that step (3) was not performed.

[0103] The differences between other embodiments and comparative examples and embodiment 1 are shown in Tables 1-1 and 1-2.

[0104] Table 1-1

[0105] Table 1-2

[0106] Wherein, the doping amount of M2 source is the doping amount of each substance in M2 source, and " / " means that this step was not performed or that the substance was not added.

[0107] The positive electrode active materials obtained in the above embodiments and comparative examples were tested as follows, and the test results are shown in Table 2.

[0108] (1) Material morphology test: obtained by scanning electron microscope of Hitachi S-4800 of Japan.

[0109] (2) Electron microscopy test of material profile: The profile of the positive electrode active material was obtained by Hitachi IM4000Ⅱ ion milling machine, and the image of the material profile was sampled by S-4800 scanning electron microscope. The image contrast was then analyzed by LIBMAS intelligent image analysis system.

[0110] (3) Test of effective yield strength: Nanoindentation tests were performed on a large number of cathode active material particles to obtain accurate load-depth curves. The hardness (H) of the cathode active material was calculated using the Oliver-Pharr method. H=P max / A c ; Among them, P maxThe maximum load measured by nanoindentation, A c It is the projected contact area under maximum load. For an ideal Glass indenter, A c = 24.56 h c 2 Contact depth h c It is the vertical distance between the tip of the indenter and the initial contact point on the surface of the positive electrode active material under maximum load.

[0111] Effective yield strength σ y eff ≈H / 3, where 3 is the constraint factor.

[0112] (4) Test of cell volume expansion rate: Through Rietveld refinement, the initial unit cell parameters a and c of the positive electrode active material were obtained. The initial state unit cell volume V is obtained. initial ; The prepared positive electrode active material was used to fabricate the electrode, and a half-cell was assembled. The electrode was charged to 4.3V (fully delithiated state), the half-cell was disassembled, the positive electrode active material was removed, and after cleaning with dimethyl carbonate (DMC), XRD patterns were collected. The charged state cell parameters a and c were obtained through Rietveld refinement. The charged state unit cell volume V is obtained. Charged ; According to ΔV max = (V charged -V initial ) / V initial ×100% yields the cell volume expansion rate.

[0113] (5) Material particle size distribution test: obtained by Marvern Hydro 2000mu laser particle size analyzer.

[0114] (6) Elemental distribution map test: Using an electron probe microanalyzer: The surface of the sample to be tested is finely polished to obtain an analytical surface with atomic-level flatness. The prepared sample is loaded into the electron probe sample chamber and evacuated to a high vacuum (≤5×10). -4 (Pa); Electron optics system alignment was performed, and an automated sample height alignment procedure was executed to precisely align the sample analysis surface to the Rowland circle focus of the wavelength dispersive spectrometer; the analytical accelerating voltage was set to 15kV-20kV, the electron beam current to 20nA, and the "smallest beam spot mode (diameter <1μm)" was selected for point analysis based on the atomic number range of the analyte. The test results of different elemental contents in different regions were plotted, and the resulting elemental distribution map is shown below. Figure 5 .

[0115] Table 2

[0116] Batteries were prepared using the aforementioned positive electrode active materials, and the specific steps are as follows: To prepare a non-aqueous electrolyte secondary battery, the following materials are required: 9.2g of positive electrode active material, 0.4g of acetylene black, 0.4g of polyvinylidene fluoride (PVDF), and aluminum foil for the positive electrode; a Li metal sheet with a diameter of 17mm and a thickness of 1mm for the negative electrode; a polyethylene porous membrane with a thickness of 25μm for the separator; and an electrolyte consisting of an equal mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) with 1 mol / L LiPF6 as the electrolyte. In addition, an Ar gas glove box with a water content and oxygen content of less than 5ppm is also required.

[0117] The preparation process of the positive electrode sheet is as follows: First, the gradient doped positive electrode active material, acetylene black and PVDF are thoroughly mixed evenly. Then, the mixture is coated on the surface of aluminum foil and pre-dried. Next, the dried coated part is stamped into an electrode sheet with a diameter of 12 mm and a thickness of 120 μm under a pressure of 100 MPa. Finally, the electrode sheet is placed in a vacuum drying oven and dried at 120℃ for 12 h to obtain the finished positive electrode sheet.

[0118] Battery assembly must be carried out in a designated Ar gas glove box. The prepared positive electrode, polyethylene porous membrane, Li metal sheet negative electrode and prepared electrolyte are placed into the glove box in sequence, and the 2025 button cell is assembled according to the button cell assembly specifications.

[0119] The batteries prepared above were tested as follows, and the test results are shown in Table 3.

[0120] (1) Discharge specific capacity in the first week: Newly assembled coin cells were subjected to constant current charge-discharge tests using a battery tester. The charge-discharge voltage range was set to 3.0V-4.3V, and the current density was 20mA / g. After the first discharge cycle, the charge-discharge capacity corresponding to the discharge curve was recorded. Combined with the mass of the positive electrode active material on the positive electrode plate, the first-cycle charge-discharge specific capacity (unit: mAh / g) was calculated. Batteries that had undergone one charge-discharge cycle were then charged to 4.3V at a current density of 20mA / g and then charged at a constant voltage of 4.3V for 30 minutes. These batteries were then designated as activated batteries and subjected to DSC testing.

[0121] (2) 100-week capacity retention rate: The battery was subjected to 100 consecutive constant current charge-discharge cycles in the voltage range of 3.0V-4.3V and the current density of 200mA / g. The discharge capacity in the first cycle and the discharge capacity in the 100th cycle were recorded. The capacity retention rate after 100 cycles was obtained by multiplying the ratio of the discharge capacity in the 100th cycle to the discharge capacity in the first cycle by 100%.

[0122] (3) Thermal decomposition temperature: Differential scanning calorimetry (DSC) was used for testing. A small amount of positive electrode active material from the activated battery was taken, cleaned with DMC, and 2 μL of electrolyte was added as a test sample into a sealed crucible. Under an inert atmosphere (such as Ar), the temperature was increased from room temperature to a specified high temperature range (such as 20℃-300℃) at a certain heating rate (usually 5℃ / min-10℃ / min). The thermal decomposition temperature of the material was determined by the temperature corresponding to the endothermic peak of the test curve.

[0123] (3) Percentage of particle breakage before and after the cycle: Fresh positive electrode sheets before cycling and positive electrode sheets after 100-cycle testing were selected respectively. After DMC cleaning treatment of the electrode surface, the microstructure of different areas was observed using a scanning electron microscope (SEM). Multiple typical fields of view were selected and images were captured. The number of broken particles and the total number of particles in each field of view were counted using image analysis software. The ratio of the number of broken particles to the total number of particles was calculated, and the average value of multiple fields of view was taken as the proportion of broken particles before and after cycling.

[0124] Table 3

[0125] Figures 1-3 The image shown is a scanning electron microscope image of the positive electrode active material prepared in Example 1 of this application. It can be seen that the particles are spherical with an average particle size of 12 μm and the surface coating layer is continuous without cracks.

[0126] Figure 6 The XRD pattern of the positive electrode active material prepared in Example 1 of this application shows that the positive electrode active material exhibits a pure α-NaFeO2 structure, indicating that the layered structure is complete.

[0127] As can be seen from Table 3, the cell volume expansion rate of the positive electrode active materials in Examples 1-18 is within the range specified in this application. The volume shrinkage reversibility of the positive electrode active materials is good, and it is not easy to cause crystal structure fatigue and cracking during the lithium insertion / extraction process, which is beneficial to improving the capacity utilization and cycle stability of the positive electrode active materials.

[0128] In Comparative Example 1, no M1 element was doped during co-precipitation, resulting in an excessively large cell volume expansion rate of the positive electrode active material, a high proportion of particle breakage after cycling, and poor thermal stability.

[0129] In Comparative Example 2, the M2 element was not doped during co-precipitation, resulting in an excessively small cell volume expansion rate of the positive electrode active material, which led to poor cycle performance of the battery.

[0130] Comparative Example 3 did not dop with M1 element during co-precipitation and did not dop with Q element during the first sintering process, resulting in excessive cell volume expansion of the positive electrode active material, which led to poor battery capacity and cycle performance.

[0131] Comparative Example 4 did not dop with M2 element during co-precipitation and did not dop with Q element during the first sintering process, resulting in an excessively small cell volume expansion rate of the positive electrode active material, a high proportion of particle breakage after cycling, and poor cycle performance and thermal stability.

[0132] Comparative Example 5 did not dope Q element during the first sintering process, resulting in excessive cell volume expansion rate of the positive electrode active material and unstable crystal structure, which led to poor cycle performance of the battery.

[0133] Comparative Example 6 did not dop with M1 and M2 elements during co-precipitation, and did not dop with Q element during the first sintering process, resulting in excessive cell volume expansion of the positive electrode active material and severe battery capacity decay.

[0134] Comparative Example 7 did not dop with M1 and M2 elements during co-precipitation, did not dop with Q element during the first sintering process, and did not undergo coating treatment, resulting in excessive cell volume expansion rate of the positive electrode active material, low thermal decomposition temperature, and severe battery capacity decay.

[0135] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A positive electrode active material, characterized in that, Based on the total content of transition metal elements in the positive electrode active material, the molar content of nickel is greater than 85%; The cell volume expansion rate of the positive electrode active material is 5.0% ~ 1.0%.

2. The positive electrode active material according to claim 1, characterized in that, The cell volume expansion rate of the positive electrode active material is 4.0% ~ 1.5%.

3. The positive electrode active material according to claim 1, characterized in that, The effective yield strength of the positive electrode active material is 1.0 GPa ~ 4.0 GPa.

4. The positive electrode active material according to claim 1, characterized in that, The positive electrode active material includes a matrix; The substrate includes a first region, a second region, and a third region distributed radially along the substrate, wherein the second region surrounds the first region, and the third region surrounds the second region. In the radial direction of the matrix, the content of element M1 at the boundary of the first region is greater than the content of element M1 at the center of the first region, and element M1 includes at least one of W, Mo, Nb and Ta. In the radial direction of the matrix, the second region includes a plurality of spaced M2 element aggregation regions, wherein the M2 element includes at least one of Mg, La, Al, Sr, Ba, Y, Zr, Ca, Fe, Zn, Sn, W, V, Mo, Sb, Ta, Ti, Nb, S, P, and B; The third region includes element Q, which includes at least two of the following: Mg, La, Al, Sr, Ba, Y, Zr, Ca, Fe, Zn, Sn, W, V, Mo, Sb, Ta, Ti, Nb, S, P, and B.

5. The positive electrode active material according to claim 4, characterized in that, In the radial direction of the substrate, the thickness of the first region is 0.5 μm to 3.5 μm; and / or, In the radial direction of the substrate, the thickness of the second region is 1.0 μm to 3.0 μm; and / or, The thickness of the third region in the radial direction of the substrate is 1.0 μm to 3.0 μm.

6. The positive electrode active material according to claim 4, characterized in that, The spacing between adjacent M2 element aggregation regions is 0.2 μm to 1.0 μm; and / or, The Q element is uniformly distributed in the third region.

7. The positive electrode active material according to any one of claims 4 to 6, characterized in that, The matrix satisfies equation I: Li 1-δ (Ni a Co b Mn c Al d ) 1-k-q M k Q q O2 of formula I; Wherein, -0.05≤δ≤0.05, a>0.85, a+b+c+d=1, 0.01≤k≤0.05, 0.01≤q≤0.05; M includes elements M1 and M2. Element M1 includes at least one of W, Mo, Nb, and Ta. Element M2 includes at least two of Mg, La, Al, Sr, Ba, Y, Zr, Ca, Fe, Zn, Sn, W, V, Mo, Sb, Ta, Ti, Nb, S, P, and B. Q includes at least two of Mg, La, Al, Sr, Ba, Y, Zr, Ca, Fe, Zn, Sn, W, V, Mo, Sb, Ta, Ti, Nb, S, P, and B.

8. The positive electrode active material according to claim 4, characterized in that, It also includes a coating layer, which is at least partially disposed on the surface of the substrate, and the coating layer includes at least one of Al2O3, ZrO2, LiPO3, LiAlO2, LLZO, LATP, Li3PO4, and LiNbO3.

9. The positive electrode active material according to claim 1 or 2, characterized in that, The primary particle size of the positive electrode active material is 200 nm to 500 nm; and / or, The grain size of the positive electrode active material is 60nm~140nm.

10. The positive electrode active material according to claim 1 or 2, characterized in that, The positive electrode active material D 50 The range is 9.5 μm to 18.5 μm; and / or, The SPAN of the positive electrode active material is 0.15~0.55; wherein, SPAN=(D 90 -D 10 ) / D 50 .

11. A method for preparing the positive electrode active material according to any one of claims 1 to 10, characterized in that, include: Nickel source, manganese source, cobalt source, aluminum source, precipitant, and complexing agent are mixed to obtain a mixed solution; M1 source is added to the mixed solution to obtain an intermediate; M2 source was added to the intermediate and co-precipitated to obtain the hydroxide precursor; The hydroxide precursor, lithium source, and Q source are mixed and subjected to a first sintering treatment to obtain a matrix, thereby obtaining the positive electrode active material.

12. The method according to claim 11, characterized in that, Adding the M2 source to the intermediate involves multiple addition operations, with an interval of 1 to 5 hours between adjacent addition operations.

13. The method according to claim 11 or 12, characterized in that, The mass percentage of M1 element in the hydroxide precursor is 2% to 5%; and / or, The mass percentage of M2 element in the hydroxide precursor is 1% to 5%.

14. The method according to claim 11 or 12, characterized in that, The heating rate of the first sintering treatment is 1℃ / min to 4℃ / min, the temperature is 720℃ to 790℃, and the time is 8h to 18h.

15. The method according to claim 11 or 12, characterized in that, Also includes: The substrate and the coating material are mixed and then subjected to a second sintering treatment. The temperature of the second sintering treatment is 250℃~450℃ and the time is 4h~12h.

16. The method according to claim 11 or 12, characterized in that, The nickel source includes at least one of nickel sulfate, nickel nitrate, nickel chloride, and nickel acetate; and / or, The cobalt source includes at least one of cobalt sulfate, cobalt nitrate, cobalt chloride, and cobalt acetate; and / or, The manganese source includes at least one of manganese sulfate, manganese carbonate, manganese nitrate, and manganese tetroxide; and / or, The aluminum source includes at least one of aluminum hydroxide, aluminum oxide, and aluminum sulfate; and / or, The M1 source includes at least one of the following: oxide, hydroxide, carbonate, fluoride, sulfate, phosphate, and chloride corresponding to the M1 element; and / or, The M2 source includes at least one of the following: oxides, hydroxides, carbonates, fluorides, sulfates, phosphates, and chlorides corresponding to the M2 element; and / or, The lithium source includes at least one of lithium hydroxide, lithium hydroxide monohydrate, lithium nitrate, lithium carbonate, and lithium acetate; and / or, The Q source includes at least one of the following: oxide, hydroxide, carbonate, fluoride, sulfate, phosphate, and chloride corresponding to the Q element.

17. A battery, characterized in that, The invention includes a positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive active material layer located on at least one side of the positive current collector, the positive active material layer comprising the positive active material according to any one of claims 1 to 10 or the positive active material prepared by the method according to any one of claims 11 to 16.

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