Positive electrode active material and preparation method thereof, positive electrode plate, battery and electric equipment

Abstract

The invention provides a positive electrode active material and a preparation method thereof, a positive electrode plate, a battery and electric equipment, the positive electrode active material comprises a compound shown in a formula I: Li < 1 + a > M < x > Q < y > O < 2-z > G < z >, a + x + y = 1, and 0 < = alt; 1, 0 < = xlt; 1, 0 < = y < lt >; 0 < = z < 2, and the positive electrode active material has a disordered rock salt structure; the positive electrode active material comprises secondary particles formed by aggregation of primary particles, the ratio of the volume distribution median particle size Dv50 of the secondary particles to the average particle size d1 of the primary particles is 10-400, the secondary particles have pores, and the porosity of the secondary particles is 10-50%. Therefore, the compaction density, the ionic conductivity and the electronic conductivity of the positive electrode active material are improved, and the proper porosity is beneficial to stress release during lattice expansion / shrinkage in the charge-discharge process, so that the generation of microcracks is reduced, and the cycle performance of the material is improved. And thus, the positive electrode active material with relatively high compaction density, particle size, rate capability and long cycle life is obtained.

Description

Technical Field

[0001] This application relates to the field of batteries, and specifically, to a positive electrode active material, a preparation method thereof, a positive electrode sheet, a battery, and an electrical device. Background Art

[0002] At present, the mainstream ternary nickel-cobalt-manganese materials are widely used in the field of electric vehicles due to their high specific capacity (>200 mAh / g) and high working voltage (>3.8 V), but they also face problems such as poor thermal stability, limited cycle life, and high cost. Although the lithium-rich manganese-based layered materials have high specific capacity (>250 mAh / g) and low cost (abundant manganese resources), problems such as voltage decay, lattice oxygen escape, and poor rate performance limit their commercial applications.

[0003] The disordered rock salt positive electrode active material can achieve a specific capacity of more than 300 mAh / g and an energy density of 1000 Wh / kg in a wide voltage range of 1.5 V to 4.8 V. In addition, this material has a three-dimensional transition metal ion skeleton structure and can still maintain structural stability in the high delithiated state, improving the cycle life and safety of the battery, and can be applied to places with harsh environments. At the same time, the disordered rock salt structure breaks the limitation of the layered arrangement of lithium ions and transition metal ions in traditional positive electrode active materials, and transition metal elements such as manganese, titanium, and iron with high abundance and low cost can be selected. This not only reduces the dependence on scarce and expensive nickel and cobalt, but also significantly reduces the material cost. In addition, the component design of this material is flexible, and a variety of different transition metal elements can be combined.

[0004] Although the disordered rock salt material has advantages such as high specific energy, wide voltage range, and flexible component design, it also faces the problem of poor ion / electron conduction. Summary of the Invention

[0005] This application aims to solve at least one of the technical problems in the related art to some extent.

[0006] In the first aspect of this application, a positive electrode active material is provided, including a compound represented by Formula Ι:

[0007] Li 1+a M x Q y O 2-z G z Formula Ι,

[0008] wherein, a + x + y = 1, 0 ≤ a < 1, 0 ≤ x < 1, 0 ≤ y < 1, 0 ≤ z < 2, M includes at least one of Mn, Fe, Co, and Ni, Q includes at least one of Ti, V, Cr, Cu, Zn, Zr, Nb, Mo, Ta, W, and Ru, G includes at least one of F, S, and P, and the positive electrode active material has a disordered rock salt structure;

[0009] The positive electrode active material includes secondary particles formed by aggregation of primary particles, and the median volume diameter Dv of the secondary particles 50 The ratio to the average diameter d1 of the primary particles is 10 - 400, the secondary particles have pores, and the porosity of the secondary particles is 10% - 50%.

[0010] The positive electrode active material with a disordered rock salt structure proposed in this application can optimize the packing structure and conductive network of the positive electrode active material, improve the ionic conductivity of the disordered rock salt material, and simultaneously achieve high tap density and high discharge capacity by controlling the particle size ratio of secondary particles to primary particles; at the same time, ensure that the secondary particles have a suitable porosity, so that the electrolyte can infiltrate into the secondary particles, improve the ion / electron conductivity, and is conducive to releasing stress during lattice expansion / contraction during charge and discharge, reducing the generation of cracks, and improving the cycle performance of the positive electrode active material.

[0011] According to some embodiments of this application, the median volume diameter Dv of the secondary particles 50 The ratio to the average diameter d1 of the primary particles is 15 - 50. Thereby, the ionic conductivity, tap density and discharge capacity of the positive electrode active material are improved.

[0012] According to some embodiments of this application, the porosity of the secondary particles is 15% - 50%, and the BET specific surface area of the secondary particles is 15m 2 / g - 30m 2 / g. Thereby, the electrolyte can infiltrate into the secondary particles, improve the ion / electron conductivity, and stress can also be released during lattice expansion / contraction during charge and discharge, reducing the generation of cracks.

[0013] According to some embodiments of this application, the pore volume V0 of the positive electrode active material is 0.01cm 3 / g - 0.1cm 3 / g, and can be optionally 0.02cm 3 / g - 0.06cm 3 / g. Thereby, while providing more lithium ion reaction channels, reducing the probability of excessive electrolyte erosion into the positive electrode active material, reducing the probability of microcrack expansion, and also improving the tap density of the material.

[0014] According to some embodiments of this application, the framework volume V of the positive electrode active material t is 0.1cm 3 / g - 0.3cm 3 / g, and can be optionally 0.2cm 3 / g - 0.25cm 3 / g, and further optionally 0.21cm3 / g - 0.24 cm 3 / g. Thus, the particle size and the intrinsic density of the positive electrode active material can be taken into account, and the charge-discharge specific capacity of the material can be improved.

[0015] According to some embodiments of the present application, the average pore diameter r of the pores is 2 nm - 300 nm, and can be optionally 50 nm - 100 nm. Thus, pores are uniformly distributed on the surface of the secondary particles, which is beneficial to the uniformity of lithium ion diffusion and reaction rate.

[0016] According to some embodiments of the present application, the proportion of the number of pores with a pore diameter r ≤ 10 nm in all the pores in the secondary particles is 40% - 80%, and can be optionally 50% - 65%. Thus, while taking into account the tap density, the lithium ion transport performance can be improved.

[0017] According to some embodiments of the present application, the volume distribution median particle size Dv of the secondary particles 50 is 3 μm - 20 μm.

[0018] According to some embodiments of the present application, the average particle size d1 of the primary particles is 0.05 μm - 2 μm, and can be optionally 0.1 μm - 0.6 μm. Thus, the average particle size of the primary particles is small, the interaction between the particles is strong, and the secondary particles can be tightly combined.

[0019] According to some embodiments of the present application, the positive electrode active material has a (200) crystal plane with 2θ = 43.6°, a (220) crystal plane with 2θ = 63.3°, and a (111) crystal plane with 2θ = 37.5°. In the X-ray diffraction pattern of the positive electrode active material, the full width at half maximum of the diffraction peak corresponding to the (200) crystal plane is 0.28 - 0.82, and the full width at half maximum of the diffraction peak corresponding to the (220) crystal plane is 0.12 - 1.2.

[0020] According to some embodiments of the present application, the positive electrode active material includes: a matrix, the matrix includes a compound represented by Formula Ι; a coating material, the coating material is located on at least part of the surface of the matrix, the coating material includes element J, and the element J includes at least one of C, Al, Zr, Ti, F, B, Cl, Br, I, S, W, Co, Sn, Mo. Thus, the side reaction between the positive electrode active material and the electrolyte is reduced, and the cycle stability of the material is improved.

[0021] According to some embodiments of the present application, the ratio of the sum of the molar numbers of element M and element Q to the molar number of element J can be 1:(0.01 - 0.1). Thus, the influence of the coating material on the porosity of the positive electrode active material is reduced, and the specific capacity, rate performance, and cycle performance of the positive electrode active material are improved.

[0022] The second aspect of the present application provides a method for preparing the positive electrode active material provided in the first aspect of the present application, and the method includes:

[0023] Mix a lithium source, an M source, a Q source, and an additive in a stoichiometric ratio, and perform a first sintering to obtain a first-sintered material, wherein the temperature of the first sintering is 750°C - 1100°C;

[0024] Crush the first-sintered material by wet grinding, and perform spray drying after crushing to obtain a dried material, and the volume median diameter Dv of the dried material 50 is 2μm - 20μm;

[0025] Perform a second sintering on the dried material to obtain the positive electrode active material, wherein the temperature of the second sintering is 150°C - 900°C.

[0026] During the preparation of the positive electrode active material in the present application, secondary particles are formed by spray drying, and the ratio of the volume median diameter Dv of the secondary particles to the average diameter of the primary particles and the porosity of the material are controlled, which can improve the transmission rates of lithium ions and electrons, improve the ionic conductivity and electronic conductivity of the material, and a suitable porosity can also reduce the generation of microcracks in the material and improve the cycling performance of the material, thereby obtaining a positive electrode active material with both high tap density, rate performance, and long cycle life. 50 According to some embodiments of the present application, the outlet air temperature of the spray drying is 100°C - 110°C, and the air pressure of the two-fluid drying is 0.1 Mpa - 0.6 Mpa. Thus, secondary particles with suitable particle sizes and porosities are obtained.

[0027] According to some embodiments of the present application, the holding time of the first sintering is 4h - 20h; and / or the holding time of the second sintering is 2h - 20h. Thus, a positive electrode active material with better crystallinity can be obtained.

[0028] According to some embodiments of the present application, the volume median diameter Dv of the slurry after wet grinding

[0029] is 0.2μm - 80μm. 50 According to some embodiments of the present application, the volume median diameter Dv of the slurry after wet grinding

[0030] The third aspect of the present application provides a positive electrode sheet, which includes the positive electrode active material provided in the first aspect of the present application or the positive electrode active material prepared by the method provided in the second aspect of the present application.

[0031] The fourth aspect of the present application provides a battery, which includes the positive electrode sheet provided in the third aspect of the present application.

[0032] The fifth aspect of the present application provides an electrical device, which includes the battery provided in the fourth aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description of embodiments in conjunction with the accompanying drawings, where:

[0034] Figure 1 FIG. shows a schematic flow chart of a method for preparing a positive electrode active material according to an embodiment of the present application.

[0035] Figure 2 FIG. shows a scanning electron microscope image of the positive electrode active material prepared in Example 1 of the present application.

[0036] Figure 3 FIG. shows a sectional view of the positive electrode active material prepared in Example 1 of the present application.

[0037] Figure 4 FIG. shows the pore size distribution in the cross-section of the positive electrode active material prepared in Example 1 of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] Embodiments of the present application will be described in detail below. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation of the present application. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the field or according to the product specifications. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0039] In a first aspect of the present application, a positive electrode active material is provided, and the positive electrode active material includes a compound represented by Formula Ι:

[0040] Li 1+a M x Q y O 2-z G z Formula Ι

[0041] wherein a + x + y = 1, 0 ≤ a < 1, 0 ≤ x < 1, 0 ≤ y < 1, 0 ≤ z < 2, M includes at least one of Mn, Fe, Co, and Ni, Q includes at least one of Ti, V, Cr, Cu, Zn, Zr, Nb, Mo, Ta, W, and Ru, G includes at least one of F, S, and P, and the positive electrode active material has a disordered rock salt structure;

[0042] The positive electrode active material includes secondary particles formed by aggregation of primary particles, and the ratio of the median volume diameter Dv 50 of the secondary particles to the average diameter d1 of the primary particles is 10 - 400, the secondary particles have pores, and the porosity of the secondary particles is 10% - 50%.

[0043] By controlling the particle size ratio of secondary particles to primary particles, the packing structure and conductive network of the cathode active material can be optimized, the ionic conductivity of the disordered rock salt material can be increased, and high tap density and high discharge capacity can be achieved simultaneously. At the same time, a suitable porosity is ensured inside the secondary particles, enabling the electrolyte to infiltrate into the secondary particles, enhancing the ion / electron conductivity, and facilitating the release of stress during lattice expansion / contraction in the charge and discharge processes, reducing crack generation during the cycling process, improving the structural stability of the cathode active material, and enhancing the cycling performance of the material.

[0044] In this application, the volume distribution median diameter Dv of the secondary particles 50 refers to the particle diameter corresponding to a cumulative volume distribution of 50% in the particle size volume distribution, which can be measured by a laser particle size analyzer.

[0045] The average particle diameter of the primary particles refers to selecting 6 - 10 spherical particles, observing the morphology through the SEM test software, automatically identifying the primary particles of the cathode material based on the SEM image using particle automation software, calculating the equivalent circle diameter of the primary particles, and calculating the average value to obtain the average size of the primary particles.

[0046] As an example, the ratio of the volume distribution median diameter Dv of the secondary particles 50 to the average particle diameter d1 of the primary particles can be 10, 50, 70, 85, 100, 115, 135, 150, 200, 300, 400, etc., or can be a range composed of any of the above values.

[0047] According to some specific embodiments of the present application, the ratio of the volume distribution median diameter Dv of the secondary particles 50 to the average particle diameter d1 of the primary particles is 15 - 50.

[0048] According to some embodiments of the present application, the volume distribution median diameter Dv of the secondary particles 50 can be 3μm - 20μm. For example, it can be 3μm, 5μm, 7μm, 9μm, 11μm, 13μm, 15μm, 17μm, 19μm, 20μm, etc., or can be a range composed of any of the above values.

[0049] According to some embodiments of the present application, the average particle diameter d1 of the primary particles can be 0.05μm - 2μm. For example, it can be 0.05μm, 0.1μm, 0.5μm, 1μm, 1.5μm, 2μm, etc., or can be a range composed of any of the above values.

[0050] According to some specific embodiments of the present application, the average particle diameter d1 of the primary particles is 0.1μm - 0.6μm.

[0051] In the present application, by making the median volume diameter Dv of the secondary particles 50 and the average diameter d1 of the primary particles within the above ranges, the interaction force between the primary particles can be increased, enabling the secondary particles to aggregate tightly, optimizing the packing structure and conductive network of the disordered rock salt material, increasing the tap density of the material, accelerating ion / electron conduction, and simultaneously achieving a high tap density and a high discharge capacity.

[0052] As an example, the porosity of the secondary particles can be 1%, 5%, 10%, 20%, 30%, 40%, 50%, etc., or can be a range composed of any of the above values.

[0053] According to some embodiments of the present application, the porosity of the secondary particles is 15% - 50%. Thereby, the tap density and conductivity of the positive electrode active material are increased, and the generation of microcracks is reduced.

[0054] If the porosity of the secondary particles is too small, the wetting effect of the electrolyte on the positive electrode active material will be affected; if the porosity of the secondary particles is too large, the mass transfer between the primary particles and ion / electron conduction will be affected, and the particle strength and tap density will also be reduced.

[0055] In the present application, the porosity of the secondary particles is the percentage of the pore volume occupying the apparent volume of the material, and the apparent volume of the material includes the pore volume and the framework volume. Specifically, through X-ray diffraction (XRD) analysis technology, first, the unit cell parameters (such as lattice constants) of the material can be obtained through XRD refinement. According to the unit cell parameters, the unit cell volume V is calculated, combined with the number of molecules or atoms Z, molar mass M, and Avogadro's constant N A , the theoretical density ρ = Z·M / N A ·V, and the calculation error is controlled within ±0.01 g / cm 3 range. Based on this theoretical density value, combined with the measured mass m of the material, the framework volume V t of the material can be accurately obtained, V t = m / ρ. Then, the framework volume is measured by the gas expansion displacement method, and the interpolation with the result obtained by XRD refinement is less than 0.002 cm 3 / g, indicating that the framework volume obtained by XRD refinement is reliable.

[0056] In the present application, the pore volume of the positive electrode active material can be tested and analyzed by a surface analyzer according to the N2 adsorption / desorption isotherm.

[0057] Exemplarily, it can be obtained by testing with a surface analyzer of the Tristar 3020 model from Micromeritics. Among them, the N2 adsorption - desorption isotherm test can specifically include: using a conventional measurement device (such as Tristar 3020), starting from a vacuum state, gradually adding N2 to the sample of the material to be tested from which the physically adsorbed components have been removed in advance, calculating the pressure change caused by N2 adsorption by the constant - volume method, and obtaining the N2 adsorption amount according to the gas equation. Thus, the N2 adsorption isotherm from 0 atmospheric pressure to 0.995 atmospheric pressure at the liquid nitrogen temperature is obtained. After reaching 0.995 atmospheric pressure, gradually reduce the N2 pressure to 0 atmospheric pressure to obtain the N2 desorption isotherm from 0.995 atmospheric pressure to 0 atmospheric pressure, and summarize to obtain the N2 adsorption - desorption isotherm. Among them, the N2 adsorption - desorption isotherm analysis is: the pore volume calculated from the N2 adsorption amount when the relative pressure (p / p0) of the N2 adsorption isotherm is 0.995.

[0058] According to some embodiments of the present application, the pore volume V0 of the positive electrode active material is 0.01 cm 3 / g - 0.1 cm 3 / g. For example, it can be 0.01 cm 3 / g, 0.03 cm 3 / g, 0.05 cm 3 / g, 0.08 cm 3 / g, 0.1 cm 3 / g.

[0059] By making the pore volume of the positive electrode active material within the above - mentioned range, on the one hand, it can provide more lithium - ion reaction channels. On the other hand, it can also reduce the probability of excessive electrolyte erosion into the material interior, reduce the risk of micro - crack expansion during charge - discharge processes, and in addition, increase the tap density of the positive electrode active material. Thus, the positive electrode active material can have both a high first - charge - discharge efficiency, good cycle performance, and a high tap density.

[0060] According to some specific embodiments of the present application, the pore volume V0 of the positive electrode active material is 0.02 cm 3 / g - 0.06 cm 3 / g. Thus, while increasing more lithium - ion reaction channels, it reduces the probability of excessive electrolyte erosion into the interior of the positive electrode active material, reduces the probability of micro - crack expansion, and can also improve the tap density of the material.

[0061] According to some embodiments of the present application, the framework volume V of the positive electrode active material t is 0.1 cm 3 / g - 0.3 cm 3 / g. For example, it can be 0.1 cm 3 / g, 0.15 cm3 / g, 0.2 cm 3 / g, 0.25 cm 3 / g, 0.3 cm 3 / g, etc., or can be a range composed of any of the above values.

[0062] In this application, the framework volume of the positive electrode active material satisfies the above range, which is beneficial to taking into account the particle size and the intrinsic density of the material, so that the positive electrode active material has a high charge-discharge specific capacity.

[0063] According to some specific embodiments of this application, the framework volume V of the positive electrode active material t is 0.2 cm 3 / g - 0.25 cm 3 / g.

[0064] According to some specific embodiments of this application, the framework volume V of the positive electrode active material t is 0.21 cm 3 / g - 0.24 cm 3 / g.

[0065] According to some embodiments of this application, the average pore diameter r of the pores can be 2 nm - 300 nm. For example, it can be 2 nm, 20 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, etc., or can be a range composed of any of the above values. Thus, pores are evenly distributed on the surface of the secondary particles, which is beneficial to the uniformity of lithium ion diffusion and reaction rate.

[0066] According to some specific embodiments of this application, the average pore diameter r of the pores can be 50 nm - 100 nm.

[0067] In this application, the test method for the average pore diameter r of the pores is as follows: The LIBMAS intelligent image analysis system performs contrast analysis on the cross-sectional electron micrograph to obtain the cross-sectional area of each pore. Assuming the pore shape in the cross-sectional electron micrograph is circular, the average cross-sectional pore diameter is obtained. Among them, the test value of each sample uses 10 particle spheres and takes the average value.

[0068] According to some embodiments of this application, the proportion of the number of pores with a pore diameter r ≤ 10 nm in all pores in the secondary particles can be 40% - 80%. Thus, while the material takes into account high tap density, it also has a high lithium ion transmission rate.

[0069] In this application, the material is cut by a high-energy ion beam, and then the cross-sectional morphology is observed by SEM. Based on the SEM image, the proportion of the number of pores with a pore diameter less than 10 nm in the positive electrode active material in all pore numbers is automatically identified using particle automation software.

[0070] For example, it can be 40%, 50%, 60%, 70%, 80%, etc., or it can be a range composed of any of the above values. Thus, the compaction density of the material and the lithium ion conduction rate are taken into account.

[0071] According to some embodiments of the present application, the proportion of pores with a pore diameter r≤10nm in all pores of the secondary particles is 50%-65%.

[0072] According to some embodiments of the present application, the positive electrode active material has a (200) crystal plane with 2θ = 43.6°, a (220) crystal plane with 2θ = 63.3°, and a (111) crystal plane with 2θ = 37.5°. In the X-ray diffraction pattern of the positive electrode active material, the full width at half maximum of the diffraction peak corresponding to the (200) crystal plane is 0.28-0.82, and the full width at half maximum of the diffraction peak corresponding to the (220) crystal plane is 0.12-1.2, that is, the positive electrode active material has a disordered rock salt structure.

[0073] According to some embodiments of the present application, the positive electrode active material includes:

[0074] a matrix, the matrix includes a compound represented by formula Ι;

[0075] a coating material, the coating material is located on at least part of the surface of the matrix, the coating material includes element J, and the element J includes at least one of C, Al, Zr, Ti, F, B, Cl, Br, I, S, W, Co, Sn, Mo.

[0076] The coating material can regulate the pore structure of the positive electrode active material to a certain extent and reduce the side reaction between the positive electrode active material particles and the electrolyte; in addition, the setting of the coating material is also beneficial to improving the cycle stability of the positive electrode active material to a certain extent.

[0077] Doping element J in the coating material can protect the positive electrode active material, reduce the side reaction between the surface of the positive electrode active material and the electrolyte, form a high-quality solid electrolyte interface film (CEI film), inhibit gas generation, and improve the storage life and electrochemical cycle performance of the positive electrode active material.

[0078] According to some embodiments of the present application, the ratio of the sum of the molar numbers of element M and element Q to the molar number of element J can be 1:(0.01-0.1). For example, it can be 1:0.01, 1:0.03, 1:0.05, 1:0.07, 1:0.09, 1:0.1, etc., or it can be a range composed of any of the above values.

[0079] By making the ratio of the sum of the molar amounts of the M element and the Q element to the molar amount of the J element within the above range, the influence of the coating material on the specific capacity and rate performance of the positive electrode active material can be reduced, enabling the positive electrode active material to have both high electrochemical activity, high energy density, high tap density, and cycle life.

[0080] The second aspect of the present application provides a method for preparing the positive electrode active material provided in the first aspect of the present application, and the method includes:

[0081] Mixing a lithium source, an M source, a Q source, and an additive in a stoichiometric ratio, and performing a first sintering to obtain a first-fired material, wherein the temperature of the first sintering is 750°C - 1100°C;

[0082] Crushing the first-fired material by wet grinding, and performing spray drying after crushing to obtain a dried material, wherein the volume median diameter Dv 50 of the dried material is 2 μm - 20 μm;

[0083] Performing a second sintering on the dried material to obtain the positive electrode active material, wherein the temperature of the second sintering is 150°C - 900°C.

[0084] In the process of preparing the positive electrode active material in the present application, secondary particles are formed by spray drying, and the ratio of the volume median diameter Dv 50 of the secondary particles to the average particle diameter d1 of the primary particles and the porosity of the material are controlled, so as to improve the transmission rates of lithium ions and electrons, increase the ionic conductivity and electronic conductivity of the material, and a suitable porosity can also reduce the generation of microcracks in the material, improve the cycle performance of the material, and thus obtain a positive electrode active material with both high tap density, rate performance, and long cycle life.

[0085] The method proposed in the present application will be described in detail below. Refer to Figure 1 and the method includes:

[0086] S10: Mixing a lithium source, an M source, a Q source, and an additive in a stoichiometric ratio, and performing a first sintering to obtain a first-fired material, wherein the temperature of the first sintering is 750°C - 1100°C

[0087] In this step, a lithium source, an M source, a Q source, and an additive are mixed in a stoichiometric ratio, the mixed raw materials are loaded into a crucible, and the first sintering is performed in an inert atmosphere to obtain a first-fired material, wherein the temperature of the first sintering is 750°C - 1100°C.

[0088] As an example, the temperature of the first sintering can be 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, etc., or can be a range composed of any of the above values.

[0089] As an example, the heat preservation time of the first sintering can be 4h - 20h. For example, it can be 4h, 8h, 12h, 16h, 20h, etc., or can be a range composed of any of the above values.

[0090] Specifically, the temperature and heat preservation time of the first sintering can be controlled according to the element composition and content to obtain a material with purer phases.

[0091] By making the temperature and heat preservation time of the first sintering within the above range, a disordered rock salt structure with fewer impurity phases and excellent crystallinity can be obtained.

[0092] According to some embodiments of the present application, transition metal sources such as M source and Q source are not limited to oxides or hydroxides of a single phase, but also include oxides or hydroxides in the form of alloys. As an example, the transition metal source can be an oxide of a single transition metal, such as Mn2O3 and TiO2, etc.; it can also be a hydroxide formed by multiple transition metals, such as Mn 0.5 Ti 0.5 (OH)2, etc.

[0093] According to some embodiments of the present application, operations such as cooling, coarse crushing, and sieving can also be included after the first sintering.

[0094] S20: Crush the first-sintered material by wet grinding, and perform spray drying after crushing to obtain a dried material, and the volume distribution median diameter Dv of the dried material 50 is 2μm - 20μm

[0095] In this step, the first-sintered material is crushed by a wet grinding process, and the qualified slurry after grinding is dried in a spray drying tower to remove moisture, forming a dried material and obtaining spherical materials.

[0096] Specifically, the first-sintered material is dispersed in water for sand grinding to form a uniform slurry. The slurry is introduced into the drying tower and contacts with hot air flow, and the moisture evaporates rapidly, and the droplets are concentrated to form preliminary particles. As the drying progresses, the diffusion of moisture inside the particles slows down, the particles shrink and gradually stabilize. At this time, the particles collide under the disturbance of the air flow, and the viscous substances on the surface cause the particles to adhere and aggregate to form larger secondary particles. The secondary particles continue to dry and solidify, and finally form secondary particles with a certain strength and a relatively high sphericity. The combination of large spherical particles and small spherical particles can further improve the tap density, ionic conductivity, and electronic conductivity of the cathode active material.

[0097] According to some embodiments of the present application, the outlet air temperature of spray drying is 100°C - 110°C. For example, it can be 100°C, 104°C, 106°C, 108°C, 110°C, etc., or it can be a range composed of any of the above values.

[0098] According to some embodiments of the present application, the air pressure of two-fluid drying is 0.2 Mpa - 0.6 Mpa. For example, it can be 0.2 Mpa, 0.3 Mpa, 0.4 Mpa, 0.5 Mpa, 0.6 Mpa, etc., or it can be a range composed of any of the above values.

[0099] By making the outlet air temperature and the air pressure of two-fluid drying within the above ranges, spherical particles with high sphericity can be obtained. The higher the outlet air temperature, the faster the water evaporation, the surface of the particles dries quickly, and it is easy to form fine particles. However, too high a temperature may cause the surface of the particles to harden, hindering the evaporation of internal water and forming larger particles. The higher the two-fluid air pressure, the finer and more uniform the atomized droplets, and the smaller the particle size formed after drying.

[0100] According to some embodiments of the present application, the volume distribution median diameter Dv of the slurry after wet grinding 50 is 0.2 μm - 80 μm. For example, it can be 0.2 μm, 1 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, etc., or it can be a range composed of any of the above values.

[0101] By making the volume distribution median diameter of the slurry within the above range, a cathode active material with a higher tap density and lithium ion transmission rate can be obtained.

[0102] S30: Perform a second sintering on the dried material to obtain the cathode active material, and the temperature of the second sintering is 150°C - 900°C

[0103] In this step, the dried material is loaded into a crucible and the second sintering is carried out in a box-type atmosphere furnace, and the sintering atmosphere is at least one of nitrogen and argon.

[0104] As an example, the temperature of the second sintering can be 150°C, 300°C, 450°C, 600°C, 750°C, 900°C, etc., or it can be a range composed of any of the above values.

[0105] According to some embodiments of the present application, the holding time of the second sintering can be 2 h - 20 h. For example, it can be 2 h, 6 h, 10 h, 14 h, 17 h, 20 h, etc., or it can be a range composed of any of the above values.

[0106] Thus, by setting the temperature and time of the second sintering within the above ranges, a cathode active material with high particle strength and fast lithium-ion transport rate can be obtained.

[0107] The cathode active material and its preparation method proposed in this application have the following advantages:

[0108] (1) The cathode active material with a rock salt structure proposed in this application has a relatively high sphericity. By controlling the ratio of the volume distribution median diameter Dv of the secondary particles 50 to the average diameter d1 of the primary particles and the porosity of the secondary particles within appropriate ranges, the packing structure and conductive network of the cathode active material can be optimized, the ionic conductivity of the disordered rock salt material can be increased, high tap density and high discharge capacity can be achieved simultaneously. At the same time, the appropriate porosity can also release stress during lattice expansion / contraction, reduce the generation of cracks during the cycling process, improve the structural stability of the cathode active material, and enhance the cycling performance of the material.

[0109] (2) By controlling the pore volume and framework volume of the cathode active material, the excessive erosion of the electrolyte on the cathode active material can be reduced, the probability of microcrack expansion can be decreased, and the tap density of the cathode active material can be increased.

[0110] (3) By controlling the average pore diameter r of the pores within an appropriate range, pores are evenly distributed on the surface of the secondary particles, which is beneficial to the uniformity of lithium-ion diffusion and reaction rate.

[0111] (4) In the preparation method of the cathode active material proposed in this application, by controlling the temperatures of the first sintering and the second sintering and the volume distribution median diameter of the dried material after spray drying, secondary particles can be obtained and the secondary particles can have appropriate particle sizes and porosities, thereby increasing the tap density, ionic conductivity, and electronic conductivity of the cathode active material.

[0112] The third aspect of this application provides a cathode electrode sheet, which includes the cathode active material provided in the first aspect of this application or the cathode active material prepared by the method provided in the second aspect of this application.

[0113] Under normal circumstances, the positive electrode sheet may include a positive electrode current collector and a positive electrode active material layer provided on at least one side of the positive electrode current collector. The positive electrode active material layer may include the above-mentioned positive electrode active material or the positive electrode active material obtained by the above preparation method. Among them, the positive electrode current collector may include, but is not limited to, metal foil sheets (such as aluminum foil and copper foil, etc.) or composite current collectors, etc. The positive electrode active material layer may also include a binder, a conductive agent, etc. Among them, the specific types and sources of the binder and the conductive agent are not particularly limited, and those skilled in the art can flexibly select according to actual needs. For example, the binder may include, but is not limited to, polyvinylidene fluoride and polyvinyl fluoride, etc., and the conductive agent may include, but is not limited to, one or more of conductive carbon black, carbon nanotubes, graphene, etc.

[0114] In the fourth aspect of the present application, a battery is provided, including the positive electrode sheet provided in the third aspect of the present application.

[0115] Under normal circumstances, in addition to the positive electrode sheet, the battery may also include a negative electrode sheet, an electrolyte, a separator, etc. Among them, the specific structures or compositions of the negative electrode sheet, the electrolyte, and the separator are not particularly limited, and those skilled in the art can flexibly select according to actual needs.

[0116] For example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material layer provided on at least one side of the negative electrode current collector. The negative electrode active material layer may include a negative electrode active material, a binder, a conductive agent, etc. Among them, the negative electrode current collector may include, but is not limited to, metal foil sheets (such as copper foil, etc.) or composite current collectors, etc. The specific types and sources of the active material, the binder, and the conductive agent in the negative electrode sheet are also not particularly limited, and those skilled in the art can flexibly select according to actual needs. For example, the negative electrode active material may include, but is not limited to, one or more of hard carbon, soft carbon, silicon-based materials, silicon-carbon materials, etc., the binder may include, but is not limited to, styrene-butadiene rubber, etc., and the conductive agent may include, but is not limited to, one or more of conductive carbon black, carbon nanotubes, graphene, etc. In addition, a thickener and other conventional components may also be selectively added to the negative electrode active material layer.

[0117] The separator may include, but is not limited to, a polyethylene (PE) membrane, a polypropylene (PP) membrane, a PP / PE / PP composite membrane, a composite ceramic separator, a coated separator, etc.

[0118] The electrolyte may include an organic solvent and an electrolyte salt. Taking a lithium battery as an example, the organic solvent may include one or more of ester solvents such as dimethyl carbonate (DMC), ethylene carbonate (EC), and ethyl methyl carbonate (EMC), and the electrolyte salt may include, but is not limited to, one or more of common lithium salts such as lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium bis(oxalato)borate (LiBOB), and lithium difluorophosphate (LiO2F2). Optionally, an additive may also be added to the electrolyte, and the additive may include, but is not limited to, common additives such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0119] The fifth aspect of the present application provides an electrical device, including the battery provided in the fourth aspect of the present application.

[0120] The specific type of the electrical device is not particularly limited, and those skilled in the art can flexibly select according to actual needs. For example, it may include, but is not limited to, electronic devices, household appliances, vehicles, and vertical takeoff and landing aircraft, etc.

[0121] The present invention will be described below with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way. For those not specified in the embodiments in terms of specific techniques or conditions, the techniques or conditions described in the literature in the art or according to the product specifications are followed. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0122] In the following embodiments, all raw materials are commercially available products without special instructions.

[0123] Example 1

[0124] Mix Mn2O3, TiO2, and Li2CO3 evenly in a high-speed mixer according to a stoichiometric ratio of 0.4:0.4:1.2. Load the mixed raw materials into a crucible and conduct the first sintering in a box-type atmosphere furnace. The sintering process requires an inert atmosphere, and the oxygen concentration in the furnace is less than 25 ppm. The first sintering temperature is 950 °C, and the holding time is 8 h.

[0125] Perform wet sanding on the sintered material. The median volume diameter Dv of the slurry after wet grinding 50 is 0.2 μm. The qualified slurry after grinding is dried through a spray drying tower to remove moisture and form a dry powder. The median volume diameter Dv of the dry material 50 is Dv 50 = 5.1 μm.

[0126] The dried powder is sintered for the second time at a temperature of 450 °C for 6 h to obtain the positive electrode active material Li 1.2 Mn 0.4 Ti 0.4 O2.

[0127] For Examples 2 - 17 and Comparative Examples 1 - 5, the preparation methods of the positive electrode active material and the battery are the same as those in Example 1, and the differences are shown in Table 1 in detail.

[0128] Table 1

[0129]

[0130]

[0131] Example 6

[0132] The preparation method of the positive electrode active material is the same as that in Example 1, except that lithium sulfide is introduced for co - sintering during the mixing process.

[0133] Example 10

[0134] The preparation method of the positive electrode active material is the same as that in Example 1, except that LiF is introduced for co - sintering during the mixing process.

[0135] Performance Test

[0136] 1. Morphology test: Obtained by testing with a scanning electron microscope of model S - 4800 from Hitachi, Japan.

[0137] 2. Skeletal volume: Through XRD analysis technology, first, the unit cell parameters (such as lattice constants) of the material can be obtained by XRD refinement. According to the unit cell parameters, the unit cell volume V is calculated. Combining the number of molecules or atoms Z, molar mass M, and Avogadro's constant N contained in the unit cell A , the theoretical density ρ = Z·M / N A ·V, and the calculation error is controlled within ±0.01 g / cm 3 range. Based on this theoretical density value, combined with the measured mass m of the material, the skeletal volume V of the material can be accurately obtained t , V t = m / ρ.

[0138] 3. Pore volume: It can be measured and analyzed by a surface analyzer according to the N2 adsorption - desorption isotherm. It can be obtained by testing with a surface analyzer of the Tristar3020 model from Micromeritics. Among them, the N2 adsorption - desorption isotherm test can specifically include: using a conventional measuring device (such as Tristar3020), starting from a vacuum state, gradually adding N2 to the sample of the material to be tested from which the physically adsorbed components have been removed in advance, calculating the pressure change caused by N2 adsorption by the constant - volume method, and obtaining the N2 adsorption amount according to the gas equation. Thus, the N2 adsorption isotherm from 0 atm to 0.995 atm at the temperature of liquid nitrogen is obtained. After reaching 0.995 atm, gradually reduce the N2 pressure to 0 atm to obtain the N2 desorption isotherm from 0.995 atm to 0 atm, and summarize to obtain the N2 adsorption - desorption isotherm. Among them, the N2 adsorption - desorption isotherm analysis is: the pore volume obtained from the N2 adsorption amount when the relative pressure (p / p0) of the N2 adsorption isotherm is 0.995.

[0139] 4. Porosity: The percentage of the pore volume in the apparent volume of the material. The apparent volume of the material includes the pore volume and the skeleton volume.

[0140] 5. Average pore diameter: The cross - sectional area of each pore is obtained by contrast analysis of the cross - sectional electron micrograph by the LIBMAS intelligent image analysis system. Assuming the pore shape in the cross - sectional electron micrograph is circular, the average cross - sectional pore diameter is obtained. Among them, the test value of each sample uses 10 particle spheres and takes the average value.

[0141] 6. Median diameter of the secondary particle volume distribution: It is obtained by testing with a laser particle size analyzer of the Hydro 3000mu model from Marvern.

[0142] 7. Proportion of the number of pores with pore diameter r ≤ 10 nm in the secondary particles among all pores

[0143] The material is cut by a high - energy ion beam, and then its cross - sectional morphology is observed by SEM. Based on the SEM image, the proportion of the number of pores with a pore diameter less than 10 nm in the cathode material among all pore numbers is automatically identified using particle automation software.

[0144] 8. Tap density

[0145] The electrode sheet is cut into a standard size, weighed, and then the thickness of the electrode sheet is measured using a special instrument (such as a micrometer). The tap density is calculated from the mass and thickness.

[0146] 9. Lithium - ion diffusion coefficient

[0147] The lithium - ion diffusion coefficient is measured using electrochemical impedance spectroscopy (EIS). By measuring the response of the battery under different conditions and combining with model calculations, the lithium - ion diffusion coefficient can be obtained.

[0148] 10. First - week discharge capacity

[0149] In the following examples and comparative examples, the electrochemical performance of the positive electrode material was tested using a 2025 - type button cell.

[0150] The preparation process of the 2025 - type button cell is as follows:

[0151] Preparation of the electrode sheet: The positive electrode active material, acetylene black, and polyvinylidene fluoride (PVDF) were fully mixed in a mass ratio of 80:10:10 with an appropriate amount of N - methylpyrrolidone (NMP) to form a uniform slurry. The slurry was coated on aluminum foil and dried at 120 °C for 12 h, and then stamped into shape under a pressure of 100 MPa to make a positive electrode sheet with a diameter of 12 mm and a thickness of 120 μm.

[0152] Battery assembly: Inside an argon - filled gas glove box with both the water content and oxygen content less than 5 ppm, the positive electrode sheet, separator, negative electrode sheet, and electrolyte were assembled into a 2025 - type button cell and then left standing for 6 h. Among them, the negative electrode sheet used a lithium metal sheet with a diameter of 17 mm and a thickness of 1 mm; the separator used a polyethylene porous membrane (Celgard 2325) with a thickness of 25 μm; the electrolyte used an equal - volume mixture of 1 mol / L LiPF6, ethylene carbonate (EC), and diethyl carbonate (DEC).

[0153] Testing of the 2025 - type button cell:

[0154] In the following examples and comparative examples, the electrochemical performance of the 2025 - type button cell was tested using a Shenzhen Neware battery test system, and the charge - discharge current density at 0.1C was 200 mA / g.

[0155] Control the charge - discharge voltage range to be 1.5 - 4.7 V. At room temperature, the button cell was subjected to charge - discharge testing at 0.05C to evaluate the electrochemical performance of the positive electrode active material.

[0156] The test results of the positive electrode active materials and batteries in Examples 1 - 17 and Comparative Examples 1 - 5 are shown in Table 2.

[0157]

[0158] It can be seen from the comparison between Examples 1 - 17 and Comparative Examples 1 - 5 that for the positive electrode active material prepared in this application, by controlling the ratio of the median particle size Dv of the volume distribution of the secondary particles to the average particle size of the primary particles and the porosity of the secondary particles within an appropriate range, the tap density and lithium - ion diffusion coefficient of the positive electrode active material can be increased, the diffusion rate of lithium ions can be increased, and the first - week discharge capacity of the battery can be improved. 50 ​

[0159] As can be seen from Examples 1-8, when the types of M element and Q element in the cathode active material with a disordered rock salt structure are different, during the material preparation process, by controlling the drying method and the sintering process, the median volume diameter Dv of the secondary particle volume distribution 50 and the ratio of the average diameter of the primary particles and the porosity of the secondary particles are within appropriate ranges, cathode active materials with a higher tap density and a higher lithium ion diffusion coefficient can be obtained, thereby improving the first cycle discharge capacity of the battery.

[0160] As can be seen from the comparison between Examples 1-9 and Example 10, a coating material can also be formed on the surface of the matrix to reduce the side reaction between the cathode active material particles and the electrolyte, while improving the tap density and lithium ion diffusion coefficient of the material, and improving the cycle performance of the cathode active material.

[0161] As can be seen from Examples 11, 12 and Examples 1, 2, by adjusting the temperature of the first sintering, the average diameter of the primary particles and the median volume diameter of the secondary particle volume distribution of the cathode active material can be controlled, and then the median volume diameter Dv of the secondary particle volume distribution 50 and the ratio of the average diameter of the primary particles. When the ratio is in the range of 15-50, the cathode active material has a higher lithium ion diffusion coefficient, which can improve the first cycle discharge capacity of the battery.

[0162] As can be seen from Examples 13, 14 and Examples 1, 2, the median volume diameter of the dried material after spray drying is relatively large, and the particle size of the primary particles in the cathode active material is relatively large. If the median volume diameter of the dried material after spray drying is relatively small, the particle size of the primary particles in the cathode active material is relatively small. When the average diameter of the primary particles is in the range of 0.1 μm - 0.6 μm, the interaction force between the primary particles can be increased, the secondary particles can be tightly aggregated, the packing structure and the conductive network of the disordered rock salt material can be optimized, and the lithium ion diffusion coefficient of the cathode active material can be improved.

[0163] As can be seen from Examples 15 and Examples 1, 2, during the preparation of the cathode active material, by adjusting the median volume diameter Dv of the slurry after wet grinding 50 , the temperature of spray drying, the two-fluid air pressure, and the median volume diameter Dv of the dried material 50 , the porosity of the secondary particles can be controlled. When the porosity is in the range of 15% - 50%, the electrolyte can infiltrate into the secondary particles, and the lithium ion diffusion coefficient can be improved.

[0164] As can be seen from Example 16, Example 17, Example 1, and Example 2, in the process of preparing the positive electrode active material, by adjusting the temperature of the first sintering, controlling the volume distribution median diameter Dv of the slurry after wet grinding 50 , the temperature of spray drying, the two-fluid air pressure, and the volume distribution median diameter Dv of the dried material 50 , the area ratio of the pores with an average pore size of less than or equal to 10 nm in the positive electrode active material can be controlled. By making the area ratio within the range of 50%-65%, the material can have both high tap density and high lithium ion transmission rate, further improving the lithium ion diffusion coefficient and the first-week discharge capacity of the battery.

[0165] From the attached Figure 2 -attached Figure 4 It can be seen that the positive electrode active material prepared in Example 1 of this application has a high sphericity, which can improve the particle strength of the positive electrode active material.

[0166] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0167] Although the embodiments of this application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting this application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A positive electrode active material, characterized in that: Including compounds shown in formula I: Li 1+a M x Q y O 2-z G z Formula Ι wherein a+x+y=1, 0≤a<1, 0≤x<1, 0≤y<1, 0≤z<2, M includes at least one of Mn, Fe, Co, and Ni, Q includes at least one of Ti, V, Cr, Cu, Zn, Zr, Nb, Mo, Ta, W, and Ru, G includes at least one of F, S, P, and B, and the positive electrode active material has a disordered rock salt structure; The positive electrode active material includes secondary particles formed by aggregation of primary particles, and the volume distribution median particle size Dv of the secondary particles is 50 The ratio of the average particle size d1 of the primary particles is 10-400, the secondary particles have pores, and the porosity of the secondary particles is 10%-50%.

2. The positive electrode active material according to claim 1, characterized in that The volume distribution median particle size Dv of the secondary particles 50 The ratio of the average particle size d1 of the primary particles is 15-50.

3. The positive electrode active material according to claim 1, characterized in that The porosity of the secondary particles is 15%-50%.

4. The positive electrode active material according to any one of claims 1 to 3, characterized in that The pore volume V0 of the positive electrode active material is 0.01 cm 3 / g-0.1cm 3 / g, optional 0.02cm 3 / g-0.06cm 3 / g.

5. The positive electrode active material according to claim 4, characterized in that The skeleton volume V of the positive electrode active material t 0.1cm 3 / g-0.3cm 3 / g, optional 0.2cm 3 / g-0.25cm 3 / g, further optional 0.21cm 3 / g-0.24cm 3 / g.

6. The positive electrode active material according to claim 5, characterized in that The average pore diameter r of the pores is 2nm-300nm, and can be optionally 50nm-100nm.

7. The positive electrode active material according to claim 6, characterized in that The number of pores with a pore size of r≤10 nm in the secondary particles accounts for 40%-80% of all pores, and can be optionally 50%-65%.

8. The positive electrode active material according to claim 1, characterized in that The volume distribution median particle size Dv of the secondary particles 50 3μm-20μm.

9. The positive electrode active material according to claim 1, characterized in that The average particle size d1 of the primary particles is 0.05 μm-2 μm, and can be optionally 0.1 μm-0.6 μm.

10. The positive electrode active material according to claim 1, characterized in that The positive electrode active material has a (200) crystal plane with 2θ=43.6°, a (220) crystal plane with 2θ=63.3° and a (111) crystal plane with 2θ=37.5°. In the X-ray diffraction pattern of the positive electrode active material, the half-peak width of the diffraction peak corresponding to the (200) crystal plane is 0.28-0.82, and the half-peak width of the diffraction peak corresponding to the (220) crystal plane is 0.12-1.

2.

11. The positive electrode active material according to claim 1, characterized in that include: A matrix, wherein the matrix comprises a compound represented by formula I; The coating material is located on at least a portion of the surface of the substrate, and the coating material includes a J element, and the J element includes at least one of C, Al, Zr, Ti, F, B, Cl, Br, I, S, W, Co, Sn, and Mo.

12. The positive electrode active material according to claim 11, characterized in that The ratio of the sum of the molar numbers of the M element and the Q element to the molar number of the J element may be 1:(0.01-0.1).

13. A method for preparing the positive electrode active material according to any one of claims 1 to 12, characterized in that: include: The lithium source, the M source, the Q source and the additive are mixed according to a stoichiometric ratio and sintered for the first time to obtain a first-sintered material, wherein the temperature of the first sintering is 750° C.-1100° C.; The burnt material is crushed by wet grinding, and then spray dried to obtain a dry material, wherein the volume distribution median particle size Dv 50 2μm-20μm; The dried material is subjected to a second sintering to obtain the positive electrode active material, and the temperature of the second sintering is 150° C.-900° C.

14. The method according to claim 13, characterized in that The outlet air temperature of the spray drying is 100°C-110°C, and the air pressure of the two-fluid drying is 0.1Mpa-0.6Mpa.

15. The method according to claim 13, characterized in that The heat preservation time of the first sintering is 4h-20h; and / or the heat preservation time of the second sintering is 2h-20h.

16. The method according to claim 13, characterized in that Volume distribution median particle size Dv of the slurry after wet grinding 50 0.2μm-80μm.

17. A positive electrode plate, characterized in that: The invention comprises the positive electrode active material according to any one of claims 1 to 12 or the positive electrode active material prepared by the method according to any one of claims 13 to 16.

18. A battery, characterized in that: Including the positive electrode sheet as described in claim 17.

19. An electrical equipment, characterized in that: Comprising the battery of claim 18.

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