POSITIVE ELECTRODE MATERIAL, ELECTROCHEMICAL APPARATUS, AND ELECTRONIC APPARATUS

Abstract

A positive electrode material, including at least one of element Al or element Zr; and particles of the positive electrode material satisfies 0.01≤(Dv99a-Dv99b)/Dv99b≤0.5, where Dv99a and Dv99b are Dv99 values of the particles of the positive electrode material measured before and after ultrasonic treatment respectively. The positive electrode material can improve processability of positive electrode materials and cycling performance of electrochemical apparatuses.

Description

TECHNICAL FIELD

This application relates to the field of electrochemical technologies, and in particular, to a positive electrode material, an electrochemical apparatus, and an electronic apparatus.

BACKGROUND

Electrochemical apparatuses (for example, lithium-ion batteries) are widely used in various fields. With the progress of society, electrochemical apparatuses are required to have better cycling performance and rate performance.

In some technologies, particle sizes of positive electrode materials are reduced to improve rate performance of electrochemical apparatuses. However, positive electrode materials with a small particle size have poor processability, are prone to self-agglomeration, and easily produce particles and bubbles during coating. In addition, uneven weight distribution easily occurs during high-speed coating, which leads to increased polarization of the electrochemical apparatuses, and easily causes local lithium precipitation, affecting cycling performance and rate performance of the electrochemical apparatuses.

SUMMARY

In view of the foregoing shortcomings of the prior art, this application improves processability and cycling performance of positive electrode materials.

This application provides a positive electrode material, where the positive electrode material includes at least one of element Al or element Zr; and

positive electrode material particles satisfies 0.01≤(D_v99_a-D_v99_b)/D_v99_b≤0.5; where D_v99_a and D_v99_b are D_v99 values of the positive electrode material particles measured before and after ultrasonic treatment respectively.

In some embodiments, the positive electrode material particles satisfies 0.01≤(D_v50_a-D_v50_b)/D_v50_b≤0.30;

where D_v50_a and D_v50_b are D_v50 values of the positive electrode material particles measured before and after ultrasonic treatment respectively.

In some embodiments, the positive electrode material satisfies at least one of the following conditions (a) to (d):

• (a) D_v50_a satisfies 2 µm≤D_v50_a≤17 µm;
• (b) D_v99_a satisfies 6 µm≤D_v99_a≤40 µm;
• (c) a specific surface area BET of the positive electrode material satisfies 0.1 m²/g≤BET≤0.9 m²/g; and
• (d) the positive electrode material includes primary particles, and an average particle size A of the primary particles satisfies 200 nm≤A≤4 µm.

In some embodiments, the positive electrode material satisfies at least one of the following conditions (e) to (i):

• (e) D_v50_a satisfies 3 µm≤D_v50_a≤6 µm;
• (f) D_v99_a satisfies 8 µm≤D_v99_a≤30 µm;
• (g) a specific surface area BET of the positive electrode material satisfies 0.5 m²/g≤BET≤0.8 m²/g;
• (h) the positive electrode material includes primary particles, and an average particle size A of the primary particles satisfies 1 µm≤A≤4 µm;and
• (i) a mass percentage of element Al in the positive electrode material ranges from 0.05% to 0.5%.

In some embodiments, the positive electrode material includes first particles and second particles, a particle size of the first particle is D1, a particle size of the second particle is D2, and D2<D1.

In some embodiments, the first particles and the second particles satisfy at least one of the following conditions (j) and (k):

• (j) 0.01≤(D_v50_a1-D_v50_b1)/D_v50_b1≤0.1; and
• (k) 0.01≤(D_v99_a1-D_v99_b1)/D_v99_b1≤0.25;
• where D_v50_a1 and D_v50_b1 are D_v50 values of the first particles measured before and after ultrasonic treatment respectively, and D_v99_a1 and D_v99_b1 are D_v99 values of the first particles measured before and after ultrasonic treatment respectively.

In some embodiments, the second particles satisfies at least one of the following conditions (1) and (m):

• (1) 0.05≤(D_v50_a2-D_v5O_b2)/D_v50_b2≤0.3; and
• (m) 0.2≤(D_v99_a2-D_v99_b2)/D_v99_b2≤1;
• where D_v50_a2 and D_v50_b2 are D_v50 values of the second particles measured before and after ultrasonic treatment respectively, and D_v99_a2 and D_v99_b2 are D_v99 values of the second particles measured before and after ultrasonic treatment respectively.

In some embodiments, the first particles and the second particles satisfy at least one of conditions (n) to (p):

• (n) 7 µm≤D_v50_a1≤15 µm;
• (o) 2 µm≤D_v50_a2≤8 µm;and
• (p) 1.5≤D_v50_a1/D_v50_a2≤5.5;
• where D_v50_a1 and D_v50_a2 are D_v50 values of the first particles and the second particles measured before ultrasonic treatment respectively.

In some embodiments, the first particles includes primary particles, an average particle size A₁ of the primary particles in the first particles satisfies 300 nm≤A₁≤800 nm; and/or the second particles includes primary particles, an average particle size A₂ of the primary particles in the second particles satisfies 0.2 µm≤A₂≤4 µm.

This application further provides an electrochemical apparatus, including:

a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; where the positive electrode includes a positive electrode current collector and a positive electrode active substance layer disposed on the positive electrode current collector, and the positive electrode active substance layer includes the positive electrode material according to any one of the foregoing embodiments.

This application further provides an electronic apparatus, including the foregoing electrochemical apparatus.

This application provides a positive electrode material, an electrochemical apparatus, and an electronic apparatus. The positive electrode material includes at least one of element Al or element Zr; and positive electrode material particles satisfies 0.01≤(D_v99_a-D_v99_b)/D_v99_b≤0.5, where D_v99_a and D_v99_b are D_v99 values of the positive electrode material particles measured before and after ultrasonic treatment respectively. The positive electrode material provided in this application can improve processability of positive electrode materials and cycling performance of electrochemical apparatuses.

DETAILED DESCRIPTION

The following embodiments may help persons skilled in the art to understand this application more comprehensively, but do not limit this application in any manner.

In the related art, a particle size of a material is reduced to improve rate performance of an electrochemical apparatus. However, a positive electrode material with a small particle size has poor processability, and is prone to self-agglomeration, leading to producing particles and bubbles during coating. In addition, uneven weight distribution easily occurs during high-speed coating, which leads to increased polarization of the electrochemical apparatus, lithium precipitation occurs, affecting cycling performance and rate performance of the electrochemical apparatus, and causing a significant temperature rise in the electrochemical apparatus.

To solve at least part of the foregoing problems, some embodiments of this application provide a positive electrode material, where the positive electrode material includes at least one of element Al or element Zr; and positive electrode material particles satisfies 0.01≤(D_v99_a-D_v99_b)/D_v99_b≤0.5. D_v99_a and D_v99_b are D_v99 values of the positive electrode material particles measured before and after ultrasonic treatment respectively.

In some embodiments of this application, the positive electrode material includes positive electrode material particles, and the positive electrode material may be, for example, a lithium cobalt oxide material containing at least one of element Al or element Zr. In some embodiments, Al may be present in a coating layer on a surface of the positive electrode material, and Zr may be doped in the positive electrode material. 0.01≤(D_v99_a-D_v99_b)/D_v99_b≤0.5 indicates a relatively small change in D_v99 of the positive electrode material particles before and after ultrasonic treatment, so it can be known that the positive electrode material has minor or nearly no self-agglomeration, thus ensuring the processability of the positive electrode material, reducing uneven distribution of the positive electrode material during coating, and reducing local lithium precipitation of the electrochemical apparatus. When the value of (D_v99_a-D_v99_b)/D_v99_b is excessively large, the electrochemical apparatus using such positive electrode material has poor cycling performance and high temperature rise. In this application, it is controlled that 0.01≤(D_v99_a-D_v99_b)/D_v99_b≤0.5, which can improve processability of the positive electrode material, prevent lithium precipitation, ensure cycling performance, and reduce temperature rise of the electrochemical apparatus using such positive electrode material.

In some embodiments of this application, particle sizes before and after ultrasonic treatment are analyzed using a Mastersizer 3000 laser particle size distribution tester. Laser particle size measurement measures particle size distribution based on a principle that particles of different sizes can cause laser to scatter at different intensities. D_v50 is a particle size where the cumulative volume distribution by volume reaches 50% as counted from the small particle size side. D_v99 is a particle size where the cumulative volume distribution by volume reaches 99% as counted from the small particle size side. When the positive electrode material particles before and after ultrasonic treatment are measured using the laser particle size analyzer, measurement conditions are the same except for the pre-ultrasonic treatment. The dispersant is water, the dispersion method is external ultrasound, the ultrasound time is 5 min, the ultrasound intensity is 40 KHz 180 w, and the sample injection operation is injecting all.

For the existing electrochemical apparatuses, in testing positive electrode materials used in the electrochemical apparatuses, the positive electrode materials in the electrochemical apparatuses can be obtained by using the following method in a drying room with 2% relative humidity. One electrochemical apparatus is selected, fully discharged, and then disassembled to obtain a positive electrode. The positive electrode is soaked in N-methylpyrrolidone (NMP) solution for 24 h, and calcined in air atmosphere at 650° C. for 5 h, an active substance layer is scrapped off from the positive electrode, the obtained positive electrode material powder is ground evenly and sieved with a 400-mesh sieve. Then, the positive electrode material powder passing through the 400-mesh sieve are collected, which is the positive electrode material.

In some embodiments, the positive electrode material particles satisfies 0.01≤(D_v50_a-D_v50_b)/D_v50_b≤0.30, where D_v50_a and D_v50_b are D_v50 values of the positive electrode material particles measured before and after ultrasonic treatment respectively. In some embodiments, the positive electrode material particles have a relatively small change in D_v50 measured before and after ultrasonic treatment, so it can be known that the positive electrode material particles have minor or nearly no self-agglomeration, which helps improve cycling performance, reduce temperature rise, and prevent local lithium precipitation of the electrochemical apparatus using the positive electrode material.

In some embodiments of this application, D_v50_a satisfies 2 µm≤D_v50_a≤17 µm, and in some embodiments, D_v50_a satisfies 3 µm≤D_v50_a≤6 µm.

In some embodiments of this application, D_v99_a satisfies 6 µm≤D_v99_a≤40 µm, and in some embodiments, D_v99_a satisfies 8 µm≤D_v99_a≤30 µm.

In some embodiments, the particle size of the positive electrode material particle affects cycling performance and temperature rise of the electrochemical apparatus using the positive electrode material. A small particle size of the positive electrode material particle leads to lower cycling capacity retention rate and higher temperature rise of the electrochemical apparatus. Therefore, in some embodiments, minimum values of D_v50_a and D_v99_a are specified. In addition, a large particle size of the positive electrode material particle affects rate performance. Therefore, in some embodiments, maximum values of D_v50_a and D_v99_a are specified.

In some embodiments, a specific surface area BET of the positive electrode material satisfies 0.1 m²/g≤BET≤0.9 m²/g, and in some embodiments, a specific surface area BET of the positive electrode material satisfies 0.5 m²/g≤BET≤0.8 m²/g. In some embodiments, an excessively small specific surface area of the positive electrode material leads to poor rate performance, while an excessively large specific surface area of the positive electrode material leads to increased electrolyte consumption in the electrochemical apparatus using the positive electrode material.

In some embodiments, the positive electrode material includes primary particles, and an average particle size A of the primary particles satisfies 200 nm≤A≤4 µm.In some embodiments, the positive electrode material includes primary particles, and an average particle size A of the primary particles satisfies 1 µm≤A≤4 µm.In some embodiments, increasing the average particle size A of the primary particles helps improve the cycling performance of the electrochemical apparatus using the positive electrode material, so a minimum value of A is specified. However, an excessively large average particle size A of the primary particles leads to increased temperature rise and reduced kinetic performance of the electrochemical apparatus using the positive electrode material, so a maximum value of A is specified. In some embodiments, some particle sizes of the positive electrode material are measured using a scanning electron microscope. After the positive electrode material in this application is imaged through a 500x scanning electron microscope (ZEISS Sigma-02-33, Germany), 200 to 600 primary particles of the positive electrode material that have a complete shape and are not blocked are randomly selected from the electron microscope image, and an average value of the longest diameters of the primary particles in the microscope image is recorded as an average particle size.

In some embodiments of this application, a mass percentage of element Al in the positive electrode material ranges from 0.05% to 0.5%.

In some embodiments of this application, the positive electrode material includes first particles and second particles, a particle size of the first particle is D1, a particle size of the second particle is D2, and D2<D1. Taylor sieve system is used in some embodiments of this application. In some embodiments, the first particles and the second particles are obtained by using the following method: In a drying room with 2% relative humidity, some of the positive electrode material are taken, dispersed in an NMP solution, ultrasonically dispersed for 12 h, and then stirred evenly to obtain a suspension. The suspension is slowly poured onto a 1500-mesh sieve while being stirred. Some small particles pass through the sieve and enter a filtrate, the filtrate is left standing for 24 h, supernatant is poured off, and powder obtained after drying is the second particles in this application. Some large particles are left on the sieve, and powder obtained after drying is the first particles in this application.

In some embodiments, the first particles and the second particles satisfy 0.01≤(D_v50_a1-D_v50_b1)/D_v50_b1≤0.1. In some embodiments, the first particles and the second particles satisfy 0.01≤(D_v99_a1-D_v99_b1)/D_v99_b1≤0.25. D_v50_a1 and D_v50_b1 are D_v50 values of the first particles measured before and after ultrasonic treatment respectively, and D_v99_a1 and D_v99_b1 are D_v99 values of the first particles measured before and after ultrasonic treatment respectively.

In some embodiments, the second particles satisfies 0.05≤(D_v50_a2-D_v50_b2)/D_v50_b2≤0.3. In some embodiments, the second particles satisfies 0.2≤(D_v99_a2-D_v99_b2)/D_v99_b2≤1. D_v50_a2 and D_v50_b2 are D_v50 values of the second particles measured before and after ultrasonic treatment respectively, and D_v99_a2 and D_v99_b2 are D_v99 values of the second particles measured before and after ultrasonic treatment respectively.

In some embodiments, when the first particles and the second particles satisfy the above conditions, it indicates that the first particles and second particles rarely agglomerate, thereby helping improve processability of the positive electrode material, and preventing lithium precipitation in the electrochemical apparatus using the positive electrode material.

In some embodiments, the first particles and the second particles satisfy 7 µm≤D_v50_a1≤15 µm.

In some embodiments, the first particles and the second particles satisfy 2 µm≤D_v50_a2≤8 µm.

In some embodiments, the first particles and the second particles satisfy 1.5≤D_v50_a1/D_v50_a2≤5.5.

D_v50_a1 and D_v50_a2 are D_v50 values of the first particles and the second particles measured before ultrasonic treatment respectively.

In some embodiments, when D_v50 of the first particles and the second particles satisfies the foregoing conditions, a positive electrode active substance layer has a good compacted density and increases the energy density of the electrochemical apparatus.

In some embodiments, the first particles includes primary particles, and an average particle size A₁ of the primary particles in the first particles satisfies 300 nm≤A₁≤800 nm.

In some embodiments, the first particles includes primary particles, and an average particle size A₁ of the primary particles in the first particles satisfies 500 nm≤A₁≤800 nm.

In some embodiments, the second particles includes primary particles, and an average particle size A₂ of the primary particles in the second particles satisfies 0.2 µm≤A₂≤4 µm.

In some embodiments, when the average particle size of the primary particles in at least one of the first particles or the second particles satisfies the foregoing conditions, electrochemical apparatuses have both good cycling performance and safety performance.

This application further provides an electrochemical apparatus, including a positive electrode, a negative electrode, and a separator.

In some embodiments of this application, the positive electrode of the foregoing electrochemical apparatus includes a positive electrode current collector and a positive electrode material disposed on the positive electrode current collector. The positive electrode material may be the positive electrode material according to any one of the foregoing embodiments.

In some embodiments, the positive electrode material includes a positive electrode material capable of absorbing and releasing lithium (Li). Examples of the positive electrode material capable of absorbing/releasing lithium (Li) may include lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadyl phosphate, lithium iron phosphate, lithium titanate, and lithium-rich manganese-based material.

Specifically, a chemical formula of lithium cobalt oxide may be chemical formula 1:

M1 is selected from at least one of nickel (Ni), manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), tungsten (W), yttrium (Y), lanthanum (La), zirconium (Zr), and silicon (Si), and values of x, a, b, and c are in the following ranges respectively: 0.8≤x≤1.2, 0.8≤a≤1, 0<b<0.2, and -0.1<c<0.2.

A chemical formula of lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide may be chemical formula 2:

M2 is selected from at least one of cobalt (Co), manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), tungsten (W), zirconium (Zr), and silicon (Si), and values of y, d, e, and f are in the following ranges respectively: 0.8≤y≤1.2, 0.3≤d≤0.98, 0.02≤e≤0.7, and -0.1≤f≤0.2.

A chemical formula of lithium manganese oxide may be chemical formula 3:

M3 is selected from at least one of cobalt (Co), nickel (Ni), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W), and values of z, g, and h are in the following ranges: 0.8≤z≤1.2, 0≤g≤1.0, and -0.2≤h≤0.2.

In some embodiments, the positive electrode of the foregoing electrochemical apparatus may be added with a conductive agent or a positive electrode binder. In some embodiments of this application, the positive electrode further includes a carbon material, and the carbon material may include at least one of conductive carbon black, graphite, graphene, carbon nanotube, carbon fiber, or carbon black. The positive electrode binder may include at least one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, styrene-acrylate copolymer, styrene-butadiene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethylcellulose, polyvinyl acetate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, or polyhexafluoropropylene.

In some embodiments, the negative electrode includes a negative electrode current collector and a negative electrode material. The negative electrode material is located on the negative electrode current collector. In some embodiments, the negative electrode current collector may include at least one of copper foil, aluminum foil, nickel foil, or fluorocarbon current collectors. In some embodiments, the negative electrode material further includes a negative electrode conductive agent and/or a negative electrode binder. In some embodiments, the negative electrode binder may include at least one of carboxymethyl cellulose (CMC), polyacrylic acid, polyvinyl pyrrolidone, polyaniline, polyimide, polyamide-imide, polysiloxane, polymerized styrene butadiene rubber, epoxy resin, polyester resin, urethane resin, or polyfluorene. In some embodiments, a mass percentage of the negative electrode binder in the negative electrode material ranges from 0.5% to 10%. In some embodiments, the negative electrode conductive agent may include at least one of conductive carbon black, ketjen black, acetylene black, carbon nanotube, vapor grown carbon fiber (VGCF), or graphene.

In some embodiments, the separator includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid. For example, polyethylene is selected from at least one of high-density polyethylene, low-density polyethylene, or ultra-high molecular weight polyethylene. Especially, polyethylene and polypropylene have a good effect on preventing short circuits, and can improve stability of a battery through a shutdown effect.

This application further provides an electronic apparatus, including the electrochemical apparatus according to any one of the foregoing embodiments. The electronic apparatus in this application is not particularly limited, and the electronic apparatus may be any known electronic apparatus in the prior art. In some embodiments, electronic apparatuses may include but is not limited to a notebook computer, a pen-input computer, a mobile computer, an electronic book player, a portable telephone, a portable fax machine, a portable copier, a portable printer, a stereo headset, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a standby power source, a motor, an automobile, a motorcycle, a power-assisted bicycle, a bicycle, a lighting appliance, a toy, a game console, a clock, an electric tool, a flash lamp, a camera, a large household battery, and the like. For example, an electronic apparatus includes a cell phone including a lithium-ion battery.

To better illustrate the beneficial effects of the positive electrode material proposed in the embodiments of this application, the following will provide description with reference to examples and comparative examples.

Example 1

Preparation of positive electrode material: A Ni_0.8Co_0.1Mn_0.1(OH)₂ precursor was prepared using the intermittent co-precipitation method to obtain a precursor with a Span of 0.60 (Span=(D_v90_a3 - D_v10_a3)/D_v50_a3, where D_v90_a3, D_v10_a3, and D_v50_a3 were particle sizes of the precursor measured before ultrasonic treatment), a BET of 10.2 m²/g, and D_v50_a3 of 10.5 µm.The precursor and LiOH were mixed at a molar ratio of Li/(Ni+Co+Mn)=1.03, a mixture was subjected to primary sintering at a primary sintering temperature of 820° C. for 16 h, washed with water, and dried to obtain a primary material. The primary material was crushed with a crushing air pressure of 0.4 MPa, washed with water, and then mixed uniformly with Al(OH)₃ at a mass ratio of Al/(Ni+Co+Mn)=0.001. The mixture was sintered at 600° C. for 6 h, and sieved through a single-layer 325-mesh vibrating sieve to obtain a positive electrode material. Parameters of the positive electrode material obtained are shown as Example 1 data in Table 2.

Preparation of positive electrode: The positive electrode material, a conductive agent Super P, and a binder polyvinylidene fluoride were mixed at a weight ratio of 97.9:0.4:1.7, N-methylpyrrolidone (NMP) was added, and the mixture was stirred well under the action of a vacuum mixer to obtain a positive electrode slurry. Then, the positive electrode slurry was applied uniformly on two surfaces of an aluminum foil positive electrode current collector, followed by drying, cold pressing, cutting, and slitting, and then was dried under vacuum to obtain a positive electrode.

Preparation of negative electrode: A negative electrode active material artificial graphite, a thickener sodium carboxymethyl cellulose, and a binder styrene-butadiene rubber were mixed at a weight ratio of 97:1:2, deionized water was added, and the resulting mixture was stirred by a vacuum mixer to obtain a negative electrode slurry. Then, the negative electrode slurry was applied uniformly on two surfaces of a copper foil negative electrode current collector, followed by drying, cold pressing, cutting, and slitting, and then was dried under vacuum to obtain a negative electrode.

Preparation of electrolyte: Ethylene carbonate, propylene carbonate, and dimethyl carbonate were mixed uniformly at a ratio of 2:2:6 in a dried argon atmosphere glove box. Lithium salt LiPF₆ was added so that concentration of the lithium salt in a finally obtained electrolyte is 1.10 mol/L. Then, 1% vinylene carbonate was added based on total weight of the electrolyte, and the solution was uniformly mixed to obtain an electrolyte.

Preparation of battery: With a polyethylene porous polymeric film as a separator, the positive electrode, the separator, and the negative electrode were stacked in sequence, so that the separator was placed between the positive and negative electrode for isolation, and the stack was wound to obtain an electrode assembly. The electrode assembly was put in an outer package aluminum-plastic film, the electrolyte was injected, and the outer package was sealed, followed by processes such as formation, degassing, and trimming to obtain a lithium-ion battery.

Examples 2 to 12

Examples 2 to 12 differ from Example 1 in that: at least one of the precursor Span, precursor BET, precursor D_v50_a3, and primary sintering temperature for preparation of the positive electrode material is different. The specific parameters are shown in Table 1.

Example 13

Example 13 differs from Example 1 in the positive electrode material preparation method. The positive electrode material preparation method used in Example 13 is as follows:

A Ni_0.8Co_0.1Mn_0.1(OH)₂ precursor was prepared by using intermittent co-precipitation method to obtain a precursor with a Span of 0.65, a BET of 16 m²/g, and D_v50_a3 of 4.5 µm, and then the precursor, LiOH, and ZrO₂ were mixed at a molar ratio of Li/(Ni+Co+Mn)=1.03 and a mass ratio of Zr/(Ni+Co+Mn)=0.003. The mixture was subjected to primary sintering at a primary sintering temperature of 850° C. for 16 h, washed with water, and dried to obtain a primary material. The primary material was crushed with a crushing air pressure of 0.6 MPa, washed with water, and then mixed uniformly with Al(OH)₃ at a mass ratio of Al/(Ni+Co+Mn)=0.001. The mixture was sintered at 600° C. for 6 h, and sieved through a double-layer vibrating sieve with 254 meshes at the upper layer and 325 meshes at the lower layer to obtain a positive electrode material.

Examples 14 to 16

Examples 14 to 16 differ from Example 13 in that: at least one of the primary sintering temperature and doping content for preparation of the positive electrode material is different. The specific parameters are shown in Table 3.

Examples 17 to 35

Examples 17 to 35 differ from Example 1 in that: the positive electrode material used in Examples 17 to 35 is obtained by mixing any two of the positive electrode materials in Examples 1 to 16. The specific parameters are shown in Table 5.

Comparative Example 1

Comparative Example 1 differs from Example 1 in the positive electrode material preparation method. The positive electrode material preparation method used in Comparative Example 1 is as follows:

A Ni_0.8Co_0.1Mn_0.1(OH)₂ precursor was prepared by using continuous co-precipitation method to obtain a precursor with a Span of 1.1, a BET of 18 m²/g, and D_v50_a3 of 4.5 µm, and then the precursor and LiOH were mixed at a molar ratio of Li/(Ni+Co+Mn)=1.03. The mixture was subjected to primary sintering at a primary sintering temperature of 820° C. for 16 h, washed with water, and dried to obtain a primary material. The primary material was crushed with a crushing air pressure of 0.6 MPa, washed with water, and then mixed uniformly with H₃BO₃ at a mass ratio of B/(Ni+Co+Mn)=0.002. The mixture was sintered at 400° C. for 6 h, and sieved through a single-layer 325-mesh vibrating sieve to obtain a positive electrode material.

Comparative Example 2

Comparative Example 2 differs from Example 1 in the positive electrode material preparation method. The positive electrode material preparation method used in Comparative Example 2 is as follows:

A Ni_0.8Co_0.1Mn_0.1(OH)₂ precursor was prepared by using continuous co-precipitation method to obtain a precursor with a Span of 1.1, a BET of 22 m²/g, and D_v50_a3 of 4.5 µm, and then the precursor and LiOH were mixed at a molar ratio of Li/(Ni+Co+Mn)=1.03. The mixture was subjected to primary sintering at a primary sintering temperature of 870° C. for 16 h, washed with water, and dried to obtain a primary material. The primary material was crushed with a crushing air pressure of 0.7 MPa, washed with water, and then mixed uniformly with H₃BO₃ at a mass ratio of B/(Ni+Co+Mn)=0.002. The mixture was sintered at 400° C. for 6 h, and sieved through a single-layer 325-mesh vibrating sieve to obtain a positive electrode material.

The lithium-ion batteries prepared in the examples and comparative examples are measured according to the following methods:

Measurement of particle sizes of the positive electrode material before and after ultrasonic treatment: Particle sizes before and after ultrasonic treatment were analyzed using a Mastersizer 3000 laser particle size distribution tester. Laser particle size measurement measures particle size distribution based on a principle that particles of different sizes can cause laser to scatter at different intensities. D_v50 is a particle size where the cumulative volume distribution by volume reaches 50% as counted from the small particle size side. D_v99 is a particle size where the cumulative volume distribution by volume reaches 99% as counted from the small particle size side. When a laser particle size tester is used to measure the particle sizes before and after ultrasonic treatment, measurement conditions are identical except for the pre-ultrasonic treatment. The dispersant is water, the dispersion method is external ultrasound, the ultrasound time is 5 min, the ultrasound intensity is 40 KHz 180 w, and the sample injection operation is injecting all.

Measurement of particle sizes of primary particles: After positive electrode materials of Examples and Comparative Examples were imaged using a 500x scanning electron microscope (ZEISS Sigma-02-33, Germany), 200 to 600 primary particles of the positive electrode materials that had a complete shape and were not blocked were randomly selected from electron microscope images, and an average value of the longest diameters of the primary particles in the microscope images was recorded as an average particle size.

Cycling performance test: The lithium-ion batteries in the following examples and comparative examples were placed in a 45° C.±2° C. thermostat and left standing for 2 hours, charged to 4.25 V at a constant current of 1.5 C, charged to 0.02 C at a constant voltage of 4.25 V and left standing for 15 minutes, and then discharged to 2.8 V at a constant current of 4.0 C. This was one charge and discharge cycle, and the first-cycle discharge capacities of the lithium-ion batteries were recorded. The charge/discharge cycle process was repeated for 500 times by using the foregoing method, and the discharge capacity at the 500^th cycle was recorded.

Four lithium-ion batteries were taken from each group to calculate an average capacity retention rate of the lithium-ion batteries. Capacity retention rate of lithium-ion battery = Discharge capacity (mAh) at the 500^th cycle/Discharge capacity (mAh) at the first cycle × 100%.

Determination of degree of lithium precipitation after cycling: The batteries after cycling were charged to 4.25 V at a constant current of 1.5 C, and then disassembled. If the negative electrode is wholly golden yellow and the gray area is less than 2%, it is determined as no lithium precipitation; if most of the negative electrode is golden yellow, but gray can be observed in some positions, and the gray area is between 2% and 20%, it is determined as slight lithium precipitation; if a portion of the negative electrode is gray, but some golden yellow can still be observed, and the gray area is between 20% and 60%, it is determined as moderate lithium precipitation; if most of the negative electrode is gray, and the gray area is more than 60%, it is determined as severe lithium precipitation.

Temperature rise test: The lithium-ion batteries in the examples and comparative examples were placed in a 25° C.±2° C. thermostat and left standing for 2 hours, charged to 4.25 V at a constant current of 1.5 C, charged to 0.02 C at a constant voltage of 4.25 V and left standing for 15 minutes, and then discharged to 2.8 V at a constant current of 10 C. This was one charge and discharge cycle. Then, such cycle process was performed once again to measure surface temperatures of the lithium-ion batteries. A difference between the surface temperature and initial lithium-ion battery temperature is the temperature rise.

Filterability: Filterability of slurry is measured by the time required for 400 mL of positive electrode slurry to pass through a 300-mesh sieve, in seconds. A shorter time means a better filterability of the slurry.

Separation of first particles and second particles: A part of the positive electrode materials were taken in a drying room with 2% relative humidity, dispersed uniformly in an NMP solution, ultrasonically dispersed for 12 h, and stirred uniformly to obtain a suspension including the positive electrode material. The suspension was slowly poured onto a 1500-mesh sieve while being stirred; some small particles passed through the sieve and entered a filtrate, the filtrate was left standing for 24 h, supernatant was poured off, and powder obtained after drying was second particles. The remaining large particles were left on the sieve, and the powder obtained after drying was first particles.

Parameters for preparation of positive electrode material in Examples 1 to 12 and Comparative Examples 1 and 2 are shown in Table 1, and test results of Examples 1 to 12 and Comparative Examples 1 and 2 are shown in Table 2.

Example	Precursor Span	Precursor BET (m2/g)	Precursor Dv50a3 (µm)	Primary sintering temperature (°C)	Crushing air pressure (MPa)	Doping element and concentration (ppm)	Coating element and concentration (ppm)	Sieving method
Example 1	0.6	10.2	10.5	820	0.4	None	Al 1000	Single-layer 325
Example 2	0.65	11	10.5	800	0.4	None	Al 1000	Single-layer 325
Example 3	0.75	12	10.5	780	0.4	None	Al 1000	Single-layer 325
Example 4	0.85	13	10.5	780	0.5	None	Al 1000	Single-layer 325
Example 5	0.6	10	13	820	0.4	None	Al 1000	Single-layer 325
Example 6	0.55	9	16	820	0.4	None	Al 1000	Single-layer 325
Example 7	0.55	8	19.5	850	0.35	None	Al 1000	Single-layer 325
Example 8	0.6	12	8	800	0.4	None	Al 1000	Single-layer 325
Example 9	0.62	14	6	800	0.4	None	Al 1000	Single-layer 325
Example 10	0.62	16	4.5	800	0.4	None	Al 1000	Single-layer 325
Example 11	0.64	19	2.5	800	0.4	None	Al 1000	Single-layer 325
Example 12	0.52	18	2	800	0.5	None	Al 1000	Single-layer 325
Comparati ve Example 1	1.1	18	4.5	820	0.6	None	B 2000	Single-layer 325
Comparati ve Example 2	1.1	22	4.5	870	0.6	None	B 2000	Single-layer 325

Example	(Dv99a-Dv99b)/Dv99b	(Dv50a-Dv50b)/Dv50b	Dv50a(µm)	Dv99a(µm)	BET(m2/g)	Particle size of primary (µm)	Filterability (400 mL) (s)	Temperture rise (∘C)	Cycling capacity retention rate	Lithium precipitation
Example 1	0.11	0.05	11.1	22.3	0.583	0.5	27.3	37.2	85%	None
Example 2	0.23	0.06	11.0	26.0	0.632	0.5	34.6	38.7	83%	None
Example 3	0.36	0.06	10.7	32.4	0.699	0.5	52.7	39.4	82%	None
Example 4	0.48	0.07	10.3	38.5	0.879	0.5	68.2	40.9	80%	None
Example 5	0.06	0.03	13.2	28.4	0.422	0.6	22.1	40.1	87%	None
Example 6	0.02	0.02	16.7	29.4	0.398	0.8	19.9	45.8	89%	Slight
Example 7	0.02	0.02	21.5	44.2	0.356	0.92	21.2	50.4	88%	Slight
Example 8	0.22	0.07	8.3	16.3	0.664	0.4	36.2	37.1	80%	None
Example 9	0.29	0.09	6.2	13.8	0.712	0.3	45.5	36.2	78%	None
Example 10	0.38	0.12	4.7	12.2	0.774	0.3	69.9	35.5	75%	None
Example 11	0.49	0.15	2.8	7.9	0.886	0.2	89.4	33.6	73%	None
Example 12	0.42	0.22	2.3	5.8	0.954	0.20	114.2	34.2	70%	None
Comparative Example 1	0.59	0.19	4.7	14.6	0.994	0.30	114.7	38.5	62%	Severe
Comparative Example 2	0.59	0.18	4.7	14.6	1.034	1.99	126.7	46.5	80%	Moderate

As shown in Table 1 and Table 2, (D_v99_a-D_v99_b)/D_v99_b of the positive electrode material is adjusted by controlling the Span, BET, primary sintering temperature, and crushing air pressure of the precursors in Examples 1 to 4. A decreased primary sintering temperature decreases the value of D_v50_a to some extent. A larger precursor Span, smaller precursor BET, lower primary sintering temperature, and lower crushing air pressure, leads to a larger value of (D_v99_a-D_v99_b)/D_v99_b of the positive electrode material, a larger value of D_v99_a, and larger positive electrode material BET. However, the excessively small Span, precursor BET, and crushing air pressure, and excessively high primary sintering temperature will lead to increased costs and decreased capacity. Therefore, these parameters need to be controlled within a range.

According to Table 2, no or slight lithium precipitation occurs in Examples 1 to 12, while lithium precipitation occurs in both Comparative Examples 1 and 2. In addition, filterability in Comparative Examples 1 and 2 is poor because the values of (D_v99_a-D_v99_b)/D_v99_b and (D_v50_a-D_v50_b)/D_v50_b are too large in Comparative Examples 1 and 2. Filterability of the slurry is mainly affected by the values of (D_v99_a-D_v99_b)/D_v99_b and (D_v50_a-D_v50_b)/D_v50_b. When such two values are larger, the positive electrode material particles agglomerate more severely, and the filterability of slurry is poorer. In the case of severe agglomeration of the positive electrode material particles, uneven coating is likely to occur during preparation of the positive electrode, causing local lithium precipitation in a lithium-ion battery. Therefore, it is specified that 0.01≤(D_v99_a-D_v99_b)/D_v99_b≤0.5 and 0.01≤(D_v50_a-D_v50_b)/D_v50_b≤0.15 in some examples of this application.

According to Table 2, the temperature rise in Comparative Example 2 is highest. This is because the temperature rise is affected by the particle size, (D_v99_a-D_v99_b)/D_v99_b and (D_v50_a-D_v50_b)/D_v50_b, where the particle size has the greatest effect. A larger particle size leads to a higher temperature rise. In addition, under the same particle size, larger values of (D_v99_a-D_v99_b)/D_v99_b and (D_v50_a-D_v50_b)/D_v50_b leads to higher temperature rise.

The cycling capacity retention rate in Comparative Example 1 is the lowest. This is because the cycling capacity retention rate is mainly affected by the particle size. A larger particle size leads to a higher cycling capacity retention rate. Under the same particle size, larger values of (D_v99_a-D_v99_b)/D_v99_b and (D_v50_a-D_v50_b)/D_v50_b leads to lower cycling capacity retention rate.

Example	Precursor Span	Precursor BET (m2/g)	Precursor Dv50a	Primary sintering temperature (°C)	Crushing air pressure (MPa)	Doping element and concentration (ppm)	Coating element and concentration (ppm)	Sieving method
Example 13	0.65	16	4.5	850	0.6	Zr 3000	Al 1000	Double-layer
Example 14	0.65	16	4.5	870	0.6	Zr 3000	Al 1000	Double-layer
Example 15	0.65	16	4.5	890	0.6	Zr 3000	Al 1000	Double-layer
Example 16	0.65	16	4.5	890	0.6	Zr 5000	Al 1000	Double-layer

Example	(Dv99a-Dv99b)/Dv99b	(Dv50a-Dv50b)/Dv50b	Dv50a(µm)	Dv99a(µm)	Positive electrode material BET (m2/g)	Particle size of primary particle (µm)	Filterability (400 mL) (s)	Temperature rise (°C)	Cycling capacity retention rate	Lithium precipitation after cycling
Example 13	0.44	0.13	4.7	10.7	0.784	1.4	77.8	36.5	89%	None
Example 14	0.37	0.12	4.9	10.2	0.752	1.9	70.4	37.2	91%	None
Example 15	0.32	0.10	5.2	9.5	0.704	2.7	52.6	38.8	93%	None
Example 16	0.25	0.08	4.6	8.3	0.683	3.4	49.5	39.6	94%	None

Parameters for the positive electrode material preparation methods in Examples 13 to 16 are shown in Table 3, and performance test results are shown in Table 4. The values of (Dv99_a-Dv99_b)/D_v99_b and (D_v50_a-D_v50_b)/D_v50_b of the positive electrode materials are adjusted by adjusting the primary sintering temperatures, doping elements and concentrations, and sieving methods in Examples 13 to 16. The sizes of primary particles are also adjusted.

According to comparison between Examples 13 to 16 and Examples 1 to 12, the cycling capacity retention rates of Examples 13 to 16 are significantly higher. This is mainly because the particle sizes of the primary particles are increased to more than 1 µm in Examples 13 to 16. When the particle sizes of the primary particles (primary particle sizes of the positive electrode materials) are large, the cycling performance is good. According to Examples 13 to 15 in Table 3, the particle sizes of the primary particles can be increased by increasing the primary sintering temperatures. According to Examples 15 and 16 in Table 3, the particle sizes of the primary particles can be increased by adding some doping elements that help melting, such as element Zr, and increasing the primary sintering temperature or adding element Zr also helps lower the values of (D_v99_a-D_v99_b)/D_v99_b and (D_v50_a-D_v50_b)/D_v50_b, so that agglomeration is alleviated. Therefore, the average value A of primary particle sizes of the positive electrode materials is limited to be not less than 1 µm in some examples.

According to comparison of Examples 13 to 16 in Table 4, as the primary particle sizes increase, the temperature rises of the lithium-ion batteries also increase, causing the kinetic performance of the lithium-ion batteries to decrease. In other words, excessively large primary particle sizes may cause deterioration in the lithium-ion battery performance. Therefore, the average value A of the primary particle sizes of the positive electrode materials is limited to be not more than 4 µm in some examples.

Example	First positive electrode material	Second positive electrode material	Mass ratio of first positive electrode material to second positive electrode material
Example 17	Example 5	Example 8	5:5
Example 18	Example 5	Example 9	5:5
Example 19	Example 5	Example 10	5:5
Example 20	Example 5	Example 11	5:5
Example 21	Example 1	Example 10	5:5
Example 22	Example 2	Example 10	5:5
Example 23	Example 3	Example 10	5:5
Example 24	Example 4	Example 10	5:5
Example 25	Example 6	Example 10	5:5
Example 26	Example 8	Example 10	5:5
Example 27	Example 4	Example 11	5:5
Example 28	Example 1	Example 13	5:5
Example 29	Example 1	Example 14	5:5
Example 30	Example 1	Example 15	5:5
Example 31	Example 1	Example 16	5:5
Example 32	Example 1	Example 15	9:1
Example 33	Example 1	Example 15	7:3
Example 34	Example 1	Example 15	3:7
Example 35	Example 1	Example 15	1:9

Example	(Dv50a2―Dv50b)/Dv50b2	(Dv99a2―Dv99bDv99b	(Dv50a1―Dv50b)/Dv50b	(Dv99a1―Dv9b)/Dv99b1	Second particles Dv50a 2 (µm)	First particles Dv50a1 (µm)	Dv5021/Dv50a2	Primary particle size A2 of second particles(µm)	Primary particle size A1 of first particles (µm)
Example 17	0.09	0.28	0.02	0.04	7.9	13.6	1.7	0.35	0.69
Example 18	0.12	0.34	0.02	0.05	5.7	13.6	2.4	0.27	0.68
Example 19	0.15	0.45	0.03	0.04	4.3	13.4	3.1	0.27	0.66
Example 20	0.18	0.56	0.02	0.06	2.4	13.3	5.5	0.20	0.68
Example 21	0.17	0.52	0.04	0.06	4.1	11.8	2.9	0.28	0.52
Example 22	0.19	0.66	0.05	0.11	3.9	11.7	3.0	0.28	0.53
Example 23	0.19	0.79	0.05	0.15	3.7	11.4	3.1	0.26	0.57
Example 24	0.24	0.87	0.05	0.19	3.4	11.2	3.3	0.27	0.55
Example 25	0.14	0.43	0.02	0.02	4.1	17.2	4.2	0.24	0.82
Example 26	0.25	0.64	0.05	0.10	3.8	8.9	2.3	0.32	0.57
Example 27	0.29	0.98	0.07	0.24	2.5	10.5	4.2	0.25	0.59
Example 28	0.14	0.49	0.04	0.07	4.2	11.6	2.8	1.24	0.57
Example 29	0.13	0.53	0.03	0.06	4.4	11.7	2.7	1.73	0.58
Example 30	0.12	0.47	0.04	0.08	4.7	11.9	2.5	2.38	0.55
Example 31	0.09	0.36	0.04	0.07	4.1	11.5	2.8	2.26	0.53
Example 32	0.14	0.54	0.05	0.07	4.6	12.2	2.7	2.01	0.56
Example 33	0.13	0.51	0.05	0.07	4.7	12.1	2.6	2.13	0.55
Example 34	0.12	0.41	0.04	0.06	4.9	11.7	2.4	2.55	0.57
Example 35	0.11	0.35	0.03	0.05	5.1	11.3	2.2	2.63	0.58

Example	Filterability (400 mL) (s)	Temperature rise (°C)	Cycling capacity retention rate	Lithium precipitation after cycling
Example 17	31.4	38.7	82%	None
Example 18	35.5	38.5	81%	None
Example 19	51.4	37.5	79%	None
Example 20	79.8	35.8	75%	None
Example 21	54.2	36.0	79%	None
Example 22	59.2	36.6	78%	None
Example 23	65.3	37.1	77%	None
Example 24	68.8	37.4	77%	None
Example 25	47.4	38.2	81%	None
Example 26	58.4	36.4	77%	None
Example 27	82.6	37.2	75%	None
Example 28	64.3	38.4	90%	None
Example 29	64.9	39.6	92%	None
Example 30	45.7	40.8	94%	None
Example 31	41.5	42.1	94%	None
Example 32	31.6	37.8	87%	None
Example 33	36.7	40.1	92%	None
Example 34	47.2	41.7	92%	None
Example 35	50.6	42.1	92%	None

In Examples 17 to 35, any two of the positive electrode materials in Examples 1 to 16 are mixed. The mixing ratios are shown in Table 5. Physical parameters for Examples 17 to 35 are shown in Table 6, and performance test results are shown in Table 7.

In Table 5, the particle size of the first positive electrode material is larger than that of the second positive electrode material; in Examples 17 to 27, combinations of large particle polycrystalline and small particle polycrystalline are used; In Examples 28 to 35, combinations of large particle polycrystalline and small particle mono-crystalline are used; and in Examples 32 to 35, different mass ratios are used. According to Table 7, in Examples 15 to 35, different mixing methods are used, but no lithium precipitation occurs after cycling, and the cycling capacity retention rates are good. Therefore, as long as the positive electrode material can satisfy 1%≤(D_v99_a-D_v99_b)/D_v99_b≤50% and 1%≤(D_v50_a-D_v50_b)/D_v50_b≤15%, the lithium-ion batteries will not experience lithium precipitation and can maintain a good cycling capacity retention rate.

The foregoing descriptions are only preferred examples of this application and explanations of the applied technical principles. Those skilled in the art should understand that the scope of disclosure involved in this application is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept, For example, a technical solution formed by replacement between the foregoing characteristics and technical characteristics having similar functions disclosed in this application.

Claims

1. A positive electrode material, comprising: at least one of element Al or element Zr; and particles of the positive electrode material satisfies 0.01≤(Dv99a-Dv99b)/Dv99b≤0.5,wherein Dv99a and Dv99b are Dv99 values of the particles of the positive electrode material measured before and after ultrasonic treatment respectively.

2. The positive electrode material according to claim 1, wherein 0.01≤(Dv50a-Dv50b)/Dv50b≤0.30, wherein Dv50a and Dv50b are Dv50 values of the particles of the positive electrode material measured before and after ultrasonic treatment respectively.

3. The positive electrode material according to claim 1, wherein the positive electrode material satisfies at least one of the following conditions (a) to (d): (a) 2 µm≤Dv50a≤17 µm; wherein Dv50a is a Dv50 value of the particles of the positive electrode material measured before ultrasonic treatment;(b) 6 µm≤Dv99a≤40 µm;(c) a specific surface area BET of the positive electrode material satisfies 0.1 m2/g≤BET≤0.9 m2/g; and(d) the positive electrode material comprises primary particles, and an average particle size A of the primary particles satisfies 200 nm≤A≤4 µm.

4. The positive electrode material according to claim 1, wherein the positive electrode material satisfies at least one of conditions (e) to (i): (e) 3 µm≤Dv50a≤6 µm; wherein Dv50a is a Dv50 value of the particles of the positive electrode material measured before ultrasonic treatment;(f) 8 µm≤Dv99a≤30 µm;(g) a specific surface area BET of the positive electrode material satisfies 0.5 m2/g≤BET≤0.8 m2/g;(h) an average particle size A of primary particles in the positive electrode material satisfies 1 µm≤A≤4 µm;and(i) a mass percentage of element Al in the positive electrode material ranges from 0.05% to 0.5%.

5. The positive electrode material according to claim 1, wherein the positive electrode material comprises first particles and second particles, a particle size of the first particle is D1, a particle size of the second particle is D2, and D2<D1.

6. The positive electrode material according to claim 5, wherein the first particles satisfies at least one of the following conditions (j) and (k): (j) 0.01≤(Dv50a1-Dv50b1)/Dv50b1≤0.1; and(k) 0.01≤(Dv99a1-Dv99b1)/Dv99b1≤0.25,wherein Dv50a1 and Dv50b1 are Dv50 values of the first particles measured before and after ultrasonic treatment respectively, and Dv99a1 and Dv99b1 are Dv99 values of the first particles measured before and after ultrasonic treatment respectively.

7. The positive electrode material according to claim 5, wherein the second particles satisfies at least one of the following conditions (l) and (m): (l) 0.05≤(Dv50a2-Dv50b2)/Dv50b2≤0.3; and(m) 0.2≤(Dv99a2-Dv99b2)/Dv99b2≤1,wherein Dv50a2 and Dv50b2 are Dv50 values of the second particles measured before and after ultrasonic treatment respectively, and Dv99a2 and Dv99b2 are Dv99 values of the second particles measured before and after ultrasonic treatment respectively.

8. The positive electrode material according to claim 5, wherein the first particles and the second particles satisfy at least one of conditions (n) to (p): (n) 7 µm≤Dv50a1≤15 µm;(o) 2 µm≤Dv50a2≤8 µm;and(p) 1.5≤Dv50a1/Dv50a2≤5.5,wherein Dv50a1 and Dv50a2 are Dv50 values of the first particles and the second particles measured before ultrasonic treatment respectively.

9. The positive electrode material according to claim 5, wherein the first particles comprise primary particles, and an average particle size A1 of the primary particles in the first particles satisfies 300 nm≤A1≤800 nm; and/orthe second particles comprises primary particles, and an average particle size A2 of the primary particles in the second particles satisfies 0.2 µm≤A2≤4 µm.

10. An electrochemical apparatus, comprising: a positive electrode;a negative electrode; anda separator disposed between the positive electrode and the negative electrode,wherein the positive electrode comprises a positive electrode current collector and a positive electrode active substance layer disposed on the positive electrode current collector, and the positive electrode active substance layer comprises a positive electrode material, the positive electrode material comprises at least one of element Al or element Zr; andparticles of the positive electrode material satisfies 0.01≤(Dv99a-Dv99b)/Dv99b≤0.5,wherein Dv99a and Dv99b are Dv99 values of the particles of the positive electrode material measured before and after ultrasonic treatment respectively.

11. The electrochemical apparatus according to claim 10, wherein 0.01≤(Dv50a-Dv50b)/Dv50b≤0.30, wherein Dv50a and Dv50b are Dv50 values of the particles of the positive electrode material measured before and after ultrasonic treatment respectively.

12. The electrochemical apparatus according to claim 10, wherein the positive electrode material satisfies at least one of the following conditions (a) to (d): (a) 2 µm≤Dv50a≤17 µm; wherein Dv50a is a Dv50 value of the particles of the positive electrode material measured before ultrasonic treatment;(b) 6 µm≤Dv99a≤40 µm;(c) a specific surface area BET of the positive electrode material satisfies 0.1 m2/g≤BET≤0.9 m2/g; and(d) the positive electrode material comprises primary particles, and an average particle size A of the primary particles satisfies 200 nm≤A≤4 µm.

13. The electrochemical apparatus according to claim 10, wherein the positive electrode material satisfies at least one of conditions (e) to (i): (e) 3 µm≤Dv50a≤6 µm; wherein Dv50a is a Dv50 value of the particles of the positive electrode material measured before ultrasonic treatment;(f) 8 µm≤Dv99a≤30 µm;(g) a specific surface area BET of the positive electrode material satisfies 0.5 m2/g≤BET≤0.8 m2/g;(h) an average particle size A of primary particles in the positive electrode material satisfies 1 µm≤A≤4 µm;and(i) a mass percentage of element Al in the positive electrode material ranges from 0.05% to 0.5%.

14. The electrochemical apparatus according to claim 10, wherein the positive electrode material comprises first particles and second particles, a particle size of the first particle is D1, a particle size of the second particle is D2, and D2<D1.

15. The electrochemical apparatus according to claim 14, wherein the first particles satisfies at least one of the following conditions (j) and (k): (j) 0.01≤(Dv50a1-Dv50b1)/Dv50b1≤0.1; and(k) 0.01≤(Dv99a1-Dv99b1)/Dy99b1≤0.25,wherein Dv50a1 and Dv50b1 are Dv50 values of the first particles measured before and after ultrasonic treatment respectively, and Dv99a1 and Dv99b1 are Dv99 values of the first particles measured before and after ultrasonic treatment respectively.

16. The electrochemical apparatus according to claim 14, wherein the second particles satisfies at least one of the following conditions (l) and (m): (l) 0.05≤(Dv50a2-Dv50b2)/Dv50b2≤0.3; and(m) 0.2≤(Dv99a2-Dv99b2)/Dv99b2≤1,wherein Dv50a2 and Dv50b2 are Dv50 values of the second particles measured before and after ultrasonic treatment respectively, and Dv99a2 and Dv99b2 are Dv99 values of the second particles measured before and after ultrasonic treatment respectively.

17. The electrochemical apparatus according to claim 14, wherein the first particles and the second particles satisfy at least one of conditions (n) to (p): (n) 7 µm≤Dv50a1≤15 µm;(o) 2 µm≤Dv50a2≤8 µm;and(p) 1.5≤Dv50a1/Dv50a2≤5.5,wherein Dv50a1 and Dv50a2 are Dv50 values of the first particles and the second particles measured before ultrasonic treatment respectively.

18. The electrochemical apparatus according to claim 14, wherein the first particles comprises primary particles, and an average particle size A1 of the primary particles in the first particles satisfies 300 nm≤A1≤800 nm; and/orthe second particles comprises primary particles, and an average particle size A2 of the primary particles in the second particles satisfies 0.2 µm≤A2≤4 µm.

19. An electronic apparatus, comprising an electrochemical apparatus, the electrochemical apparatus comprises: a positive electrode;a negative electrode; anda separator disposed between the positive electrode and the negative electrode,wherein the positive electrode comprises a positive electrode current collector and a positive electrode active substance layer disposed on the positive electrode current collector, and the positive electrode active substance layer comprises a positive electrode material, the positive electrode material comprises at least one of element Al or element Zr; andparticles of the positive electrode material satisfies 0.01≤(Dv99a-Dv99b)/Dv99b≤0.5,wherein Dv99a and Dv99b are Dv99 values of the particles of the positive electrode material measured before and after ultrasonic treatment respectively.

20. The electronic apparatus according to claim 19, wherein 0.01≤(Dv50a-Dv50b)/Dv50b≤0.30, wherein Dv50a and Dv50b are Dv50 values of the particles of the positive electrode material measured before and after ultrasonic treatment respectively.