Ternary positive electrode material and preparation thereof, positive plate, battery, battery pack and electric equipment

Abstract

The invention provides a ternary positive electrode material and a preparation method thereof, a positive plate, a battery, a battery pack and electric equipment, the ternary positive electrode material comprises secondary particles DA, the secondary particles DA comprise a plurality of primary particles EA, and at least part of the primary particles EA in the secondary particles DA extend from the center of the secondary particles DA to the surface of the secondary particles DA; the exposed ratio of the (010) crystal face of the ternary positive electrode material is greater than or equal to 82%, and the ternary positive electrode material can improve the structural stability and the ionic conductivity of the ternary positive electrode material, and improve the electrochemical performance such as the rate and the cycling stability of the battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of batteries, in particular to a ternary positive electrode material, a preparation method thereof, a positive electrode sheet, a battery, a battery pack and an electrical equipment. BACKGROUND

[0002] In a battery, a ternary positive electrode material becomes the core component of a high-energy-density battery due to its high specific capacity. However, in the existing ternary positive electrode material, the crystal lattice expands and shrinks with the repeated intercalation / deintercalation of active ions (for example, lithium ions) in the cycle process, and the increased stress between the ternary positive electrode material particles will lead to the problem of poor contact between the particles, accelerating the failure of the ternary positive electrode material. At the same time, when the grain size of the ternary positive electrode material exceeds the critical grain size, the ternary positive electrode material begins to crack, which may cause mechanical failure and ion conductivity reduction of the ternary positive electrode material particles.

[0003] Therefore, in the prior art, due to the poor structural stability and poor ion conductivity of the ternary positive electrode material and other factors, the electrochemical performance of the battery, such as the rate performance and cycle stability, is poor, which needs to be solved urgently. SUMMARY

[0004] The embodiments of the present application provide a ternary positive electrode material, a preparation method thereof, a positive electrode sheet, a battery, a battery pack and an electrical equipment, which can improve the structural stability and ion conductivity of the ternary positive electrode material, and improve the electrochemical performance of the battery, such as the rate performance and cycle stability.

[0005] In a first aspect, the embodiments of the present application provide a ternary positive electrode material, which includes secondary particles DA, the secondary particles DA include a plurality of primary particles EA, at least part of the primary particles EA in the secondary particles DA extend from the center of the secondary particles DA to the surface of the secondary particles DA; the exposure ratio of the (010) crystal face of the ternary positive electrode material is greater than or equal to 82%.

[0006] In a possible implementation, the number ratio of the primary particles EA in the secondary particles DA, which extend from the center of the secondary particles DA to the surface of the secondary particles DA, is greater than or equal to 90%.

[0007] In a possible implementation, the exposure ratio of the (010) crystal face of the ternary positive electrode material is 82% to 98%; and / or, the particle size of the ternary positive electrode material is 3 μm to 5 μm.

[0008] In a possible implementation, in the X-ray diffraction test result of the ternary positive electrode material, the ratio of the peak intensity I （003） of the (003) diffraction peak to the peak intensity I （104) of the (104) diffraction peak is 1.27 to 1.33.

[0009] In a possible implementation, the primary particles EA include nanosheets.

[0010] In a possible implementation, the chemical formula of the ternary positive electrode material is shown in Formula 1: LiNi a Co b M 1-a-b-c N c O2 Formula 1, wherein 0.6≤a≤0.8, 0.1≤b≤0.2, 0≤c≤0.1, M is selected from manganese and / or aluminum, and N is selected from one or more of aluminum, zirconium, tungsten, titanium, magnesium, calcium, boron, strontium, niobium, molybdenum, and tantalum.

[0011] In a second aspect, an embodiment of the present application provides a preparation method of the ternary positive electrode material, including the following steps: performing a co-precipitation reaction on a mixed solution including a metal source and a solvent to obtain a ternary material precursor, wherein the co-precipitation reaction is performed at a temperature of 50°C to 70°C; and performing a sintering treatment on a mixture including the ternary material precursor and a lithium source to obtain the ternary positive electrode material; wherein the ternary material precursor includes secondary particles DB, and at least part of primary particles EB in the secondary particles DB extends from the center of the secondary particles DB to the surface of the secondary particles DB.

[0012] In a possible implementation, the mixed solution further includes a chelating agent, and the concentration of the chelating agent in the mixed solution is 0.8 mol / L to 2 mol / L.

[0013] In a possible implementation, the chelating agent includes ammonia water; and / or, the pH of the mixed solution is 10 to 12; and / or, during the co-precipitation reaction, the mixed solution is stirred by a impeller, and the peripheral speed of the impeller is 600 rpm to 1200 rpm; and / or, the time of the co-precipitation reaction is 5 h to 12 h.

[0014] In a possible implementation, the sintering treatment includes: performing a first sintering treatment on the mixture, and then performing a second sintering treatment to obtain the ternary positive electrode material; wherein the temperature of the first sintering treatment is 500°C to 550°C, and the time of the first sintering treatment is 4 h to 6 h; and the temperature of the second sintering treatment is 700°C to 800°C, and the time of the second sintering treatment is 10 h to 14 h.

[0015] In a third aspect, an embodiment of the present application provides a positive electrode sheet, including a positive electrode current collector and a positive electrode active layer located on at least one side of the positive electrode current collector, and the positive electrode active layer includes the ternary positive electrode material or the ternary positive electrode material prepared according to the preparation method.

[0016] In a possible implementation, the positive electrode active layer further comprises a solid-state electrolyte; preferably, the mass ratio of the ternary positive electrode material to the solid-state electrolyte is (8:2)~(9:1).

[0017] In a fourth aspect, an embodiment of the present application provides a single battery, comprising the positive electrode sheet.

[0018] In a fifth aspect, an embodiment of the present application provides a battery pack, comprising at least two single batteries as described above.

[0019] In a sixth aspect, an embodiment of the present application provides an electrical equipment, comprising the battery or the battery pack as described above.

[0020] The ternary positive electrode material provided by the embodiment of the present application comprises secondary particles DA, and at least part of primary particles EA in the secondary particles DA extends from the center of the secondary particles DA to the surface of the secondary particles DA, so that active ions (such as lithium ions) can smoothly diffuse from the center of the secondary particles DA to the surface without passing through the grain boundary, which improves the diffusion coefficient of the active ions, and further improves the ionic conductivity of the ternary positive electrode material and the rate performance of the battery. Meanwhile, the exposure ratio of the (010) crystal face of the ternary positive electrode material is greater than or equal to 82%, which ensures that the ternary positive electrode material has a substantially consistent crystal orientation, so as to inhibit the volume change of the ternary positive electrode material in the charging and discharging process, significantly inhibit the pulverization and cracking of the secondary particles DA, improve the structural stability of the ternary positive electrode material, and further improve the cycle stability of the battery. Therefore, the present application can improve the structural stability and ionic conductivity of the ternary positive electrode material, and further improve the rate performance and cycle stability of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0022] Figure 1 a1 of FIG. 1 is a structural schematic diagram of the initial structure of the randomly polymerized ternary positive electrode material in Comparative Example 1; Figure 1 a2 of FIG. 2 is a structural schematic diagram of the structure after the randomly polymerized ternary positive electrode material in Comparative Example 1 is cycled for 200 times; Figure 1 b1 of FIG. 3 is a structural schematic diagram of the initial structure of the ternary positive electrode material in the embodiment of the present application; Figure 1 b2 of FIG. 4 is a structural schematic diagram of the structure after the ternary positive electrode material in the embodiment of the present application is cycled for 200 times;

[0023] Figure 2 a of FIG. 5 is a front view of the ternary material precursor in Comparative Example 1, Figure 2b is a front view of the ternary material precursor in Embodiment 1 of the present invention;

[0024] Figure 3 a1 is a front view of the randomly aggregated ternary cathode material in Comparative Example 1. Figure 3 a2 is a cross-sectional view of the randomly polymerized ternary cathode material in Comparative Example 1. Figure 3 b1 is a front view of the ternary cathode material in Embodiment 1 of the present invention. Figure 3 b2 is a cross-sectional view of the ternary cathode material in Embodiment 1 of the present invention;

[0025] Figure 4 'a' is a cross-sectional view of the positive electrode in Comparative Example 1 after 200 cycles; Figure 4 b is a cross-sectional view of the positive electrode in Example 1 after 200 cycles.

[0026] Reference numerals: 1: Ternary cathode material in Comparative Example 1; 2: Ternary cathode material in Example 1; 3: Li6PS5Cl solid electrolyte.

[0027] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0028] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0029] Existing ternary cathode materials suffer from lattice volume changes due to repeated insertion / extraction of active ions during charging and discharging, leading to problems such as particle cracks and increased interfacial impedance. This severely restricts the industrial application of solid-state batteries. Therefore, developing ternary cathode materials with high structural stability and excellent electrochemical performance is the key to the current development of solid-state battery technology.

[0030] According to the research of the inventor, in the ternary positive electrode material existing in the form of secondary particles, the random orientation of the primary particles in the secondary particles will cause serious anisotropy and volume change and lattice mismatch of the primary particle grains, which will produce uneven stress and strain, and easily form cracks along the grain boundaries in the cycle process, finally accelerate the structural deterioration of the internal secondary particles in the cycle process, hinder the migration of active ions and electrons, and cause the increase of interface impedance and capacity attenuation. While in the ternary positive electrode material existing in the form of primary particles, the primary particle crystals are randomly oriented, there is no unified active ion diffusion channel, and the active ions need to pass through multiple grain boundaries to reach the surface of the particles, which increases the diffusion path and resistance of the active ions. At the same time, the degree of cation mixing of the primary particles is high, and the repeated intercalation / deintercalation of active ions (such as lithium ions) during charging and discharging will also cause lattice volume change. All these will deteriorate the rate and cycle performance of the battery.

[0031] Therefore, the embodiment of the present application provides a ternary positive electrode material, which comprises secondary particles DA, the secondary particles DA comprise a plurality of primary particles EA, at least part of the primary particles EA in the secondary particles DA extend from the center of the secondary particles DA to the surface of the secondary particles DA; the exposure ratio of the (010) crystal plane of the ternary positive electrode material is greater than or equal to 82%.

[0032] According to the research of the inventor, the above-mentioned ternary positive electrode material can improve the structural stability and ion conductivity of the ternary positive electrode material, and improve the electrochemical performance such as the rate and cycle stability of the battery. The reason is that at least part of the primary particles EA in the secondary particles DA extend from the center of the secondary particles DA to the surface of the secondary particles DA (which can be called radial extension), and the active ions (such as lithium ions) can directly diffuse from the center of the secondary particles DA to the surface without passing through the grain boundaries, thereby constructing a convenient three-dimensional active ion channel, improving the diffusion coefficient of the active ions, and further improving the ion conductivity of the ternary positive electrode material; at the same time, the (010) crystal plane of the ternary positive electrode material is also beneficial to the transmission of active ions, which can improve the rate performance of the battery. The degree of cation mixing of the radially extended primary particles DA is low, which can reduce the lattice volume change of the primary particles DA caused by the repeated intercalation / deintercalation of active ions during the cycle; and the exposure ratio of the (010) crystal plane of the crystal structure of the ternary positive electrode material is greater than or equal to 82%, so that the primary particles in the secondary particles EA have a basically consistent crystal orientation, and the radially primary particles EA with a basically consistent crystal orientation can significantly reduce the intergranular stress caused by volume change during charging and discharging through cooperative expansion and contraction, which can significantly inhibit the pulverization and cracking of the secondary particles DA, improve the structural stability of the ternary positive electrode material, and further improve the cycle stability of the battery.

[0033] If the exposure ratio of the (010) crystal plane of the ternary positive electrode material is less than 82%, the crystal orientation of the primary particles EA tends to be disordered, the active ion diffusion channel is disordered, the active ion needs to pass through multiple grain boundaries to reach the surface of the particle, increasing the diffusion path and resistance of the active ion, which cannot coordinate to significantly reduce the intergranular stress caused by volume change in the charging and discharging process, leading to the pulverization and cracking of the secondary particles DA, the structural stability of the ternary positive electrode material is reduced, and the rate performance and cycle stability of the battery are decreased.

[0034] Therefore, in the ternary positive electrode material of the embodiments of the present application, at least part of the primary particles EA in the secondary particles DA extends from the center of the secondary particles DA to the surface of the secondary particles DA, and the exposure ratio of the (010) crystal plane of the ternary positive electrode material is greater than or equal to 82%. Under such a structure system of the ternary positive electrode material, the structural stability and ion conductivity of the ternary positive electrode material can be improved, and the rate performance and cycle stability of the battery can be improved.

[0035] In addition, according to the research of the inventor, improving the structural stability of the ternary positive electrode material can avoid the failure of the ternary positive electrode material and improve the utilization rate and reversible capacity of the ternary positive electrode material. The exposure ratio of the (010) crystal plane of the ternary positive electrode material is greater than or equal to 82%, which indicates that it has high crystallinity and isotropic orientation. Due to the high crystallinity and isotropic orientation of the radially extending primary particles EA in the secondary particles DA, the ternary positive electrode material particles have a continuous active ion diffusion path and a small active ion diffusion resistance, which can realize higher mechanical strength and more uniform electrochemical reaction of the ternary positive electrode material. At the same time, the high structural stability of the primary particles EA can effectively inhibit the side reaction and reduce the gas release, avoiding the swelling of the battery.

[0036] In some embodiments, the number ratio of the primary particles EA extending from the center of the secondary particles DA to the surface of the secondary particles DA in the secondary particles DA is greater than or equal to 90%, i.e., the proportion of the number of the primary particles EA extending from the center of the secondary particles DA to the surface of the secondary particles DA to the total number of the primary particles DA in the secondary particles DA is greater than or equal to 90%. This is more conducive to the smooth diffusion of active ions (lithium ions) from the center to the surface of the secondary particles DA without passing through the grain boundary, and the diffusion of active ions from the surface to the center of the secondary particles DA without passing through the grain boundary, reducing the diffusion resistance of active ions in the ternary positive electrode material during the charging and discharging process of the battery, improving the rate performance of the battery, while improving the structural stability of the ternary positive electrode material, improving the cycle stability of the battery, and other performances.

[0037] In this embodiment of the invention, the proportion of primary particles EA extending from the center of the secondary particle DA to its surface can be tested using the following method. For example, scanning electron microscopy (SEM) can be used. The aforementioned ternary cathode material particles are taken, and a cross-section of the ternary cathode material particles is prepared using focused ion beam (FIB) to create a test sample. Multiple SEM cross-sectional images (50 μm × 50 μm) are acquired at different locations to ensure coverage of different areas of the sample. For example, SEM cross-sectional images are acquired at three locations. The proportion of primary particles EA extending from the center of the secondary particle DA to its surface in each SEM cross-sectional image is manually counted, and the average value is taken as the proportion of primary particles EA extending from the center of the secondary particle DA to its surface.

[0038] In some embodiments, the (010) crystal plane exposure ratio of the ternary cathode material is 82% to 98%, for example, it can be a range of 82%, 85%, 88%, 91%, 94%, 96%, 98% or any two of them. On the basis of improving the structural stability of the ternary cathode material, it is more conducive to improving the ionic conductivity of the ternary cathode material and improving the rate performance of the battery.

[0039] In this embodiment of the invention, the (010) crystal plane of the ternary cathode material is the side surface parallel to the c-axis of the layered structure of the ternary cathode material. The (010) crystal plane exposure ratio of the ternary cathode material refers to the percentage of the exposed (010) crystal plane area on the surface of the ternary cathode material out of the total exposed crystal plane area. This can be tested using the following method: specifically, electron backscatter diffraction (EBSD) testing.

[0040] S1: Polish the above-mentioned ternary cathode material particles to obtain ternary cathode material particles with smooth surfaces, ensuring that the electron beam can effectively act on the ternary cathode material particles with smooth surfaces.

[0041] S2: Place the ternary cathode material particles with smooth surfaces on the sample stage of the EBSD equipment, and use an electron beam to scan the surface of the ternary cathode material particles with smooth surfaces point by point, collect data at each point, and obtain crystal orientation distribution information at each point.

[0042] S3: Count the points where the angle between the crystal plane normal and the sample surface normal is ≤10° (determine as (010) crystal plane exposure), and calculate the (010) crystal plane exposure ratio of the ternary cathode material = number of points that meet the condition / total number of points × 100%.

[0043] In some embodiments, in the X-ray diffraction test results of the ternary cathode material, the peak intensity I of the (003) diffraction peak is... （003） The peak intensity I of the (104) diffraction peak （104) The ratio I（003） / I （104） may be 1.27~1.33. For example, I （003） / I （104） may be 1.27, 1.29, 1.31, 1.33 or a range consisting of any two of them. I （003） / I （104） not less than 1.27, which is conducive to further improving the degree of cationic disorder in primary particles, the strong phase change resistance of the structure of the ternary positive electrode material, and the stability of the layered structure of the ternary positive electrode material. I （003） / I （104） not greater than 1.33, which is conducive to the preparation of the ternary positive electrode material. Therefore, I （003） / I （104） is 1.27~1.33, which is more conducive to improving the performance of the ternary positive electrode material.

[0044] In the embodiment of the present application, the ternary positive electrode material has a typical α-NaFeO2 type layered structure (R-3m space group), and the XRD diffraction peak corresponds to a specific crystal face: the (003) diffraction peak belongs to the "interlayer characteristic peak in the c-axis direction", which reflects the integrity of the layered structure of the material, the peak intensity of the (003) diffraction peak can directly reflect the regularity of the layered structure of the ternary positive electrode material, the stronger the (003) diffraction peak, the more complete the layered structure of the ternary positive electrode material; the (104) diffraction peak belongs to the "characteristic peak in the ab plane", and the peak intensity is relatively stable (which can be used as a reference), which is used for normalization to eliminate the influence of non-specific factors such as sample thickness and crystallinity, and the ratio I （003） / I （104） is a core index for evaluating the regularity of the crystal structure, the degree of layering and the degree of cationic disorder of the ternary positive electrode material. I （003） , I （104） may be measured by the following method: specifically, the X-ray diffraction (XRD) test can be used, the ternary positive electrode material is subjected to XRD test, hexagonal LiNO2 (R-3m) is used as a reference, the peak intensity value of (003) and the peak intensity value of (104) of the ternary positive electrode material are recorded, and I (003) / I (104) peak intensity ratio is obtained.

[0045] In some embodiments, the particle size of the ternary positive electrode material can be 3 μm to 5 μm, for example, can be 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm or a range consisting of any two of them, and the particle size is the average particle size of the ternary positive electrode material. The particle size of the ternary positive electrode material is not less than 3 μm, which can further reduce the specific surface area of the ternary positive electrode material, is conducive to inhibiting the occurrence of side reactions, reducing battery outgassing, and improving the safety performance of the battery; the particle size of the ternary positive electrode material is not greater than 5 μm, which is more conducive to inhibiting the volume change of primary particles EA during charging and discharging, reducing intergranular stress, inhibiting the pulverization and cracking of secondary particles DA, improving the structural stability of the ternary positive electrode material, and shortening the transmission path of active ions. Therefore, the particle size of the ternary positive electrode material is 3 μm to 5 μm, which is more conducive to improving the performance of the battery.

[0046] In the embodiments of the present application, the particle size of the ternary positive electrode material can be measured by the following method: using SEM test, taking the SEM image of the ternary positive electrode material, using ImageJ software to measure the particle size and quantity of the ternary positive electrode material existing in the secondary particles DA and the primary particles EA and the secondary particles DA existing alone, and calculating the average particle size of the ternary positive electrode material by the particle size of the ternary positive electrode material = (particle size of primary particles EA x quantity of primary particles EA + particle size of secondary particles EA x quantity of secondary particles EA) / (quantity of primary particles EA + quantity of secondary particles EA).

[0047] In some embodiments, the primary particles EA include nanosheets, the particle size of the primary particles EA is the maximum length of the nanosheets, the primary particles have a nanosheet structure with exposed (010) crystal faces, and the primary particles EA with the same crystal face orientation can further improve the stress release capability. The thin sheet structure of the nanosheet has higher "structural flexibility", which can disperse stress through slight deformation when the volume expands, avoid cracking of the secondary particles EA due to stress concentration, improve the structural stability of the ternary positive electrode material, and improve the cycle stability of the battery.

[0048] Generally, the primary particles EA in the secondary particles DA are nanosheets, which are distributed radially, that is, the primary particles EA in the secondary particles DA extend from the center of the secondary particles DA to the surface of the secondary particles DA.

[0049] In some embodiments, the chemical formula of the ternary positive electrode material is shown as formula 1:

[0050] LiNi a Co b M 1-a-b-c N c O2 Formula 1,

[0051] Wherein, 0.6≤a≤0.8, 0.1≤b≤0.2, 0≤c≤0.1, for example, a can be 0.6, 0.7, 0.8 or a range composed of any two of them, b can be 0.1, 0.15, 0.2 or a range composed of any two of them, c can be 0, 0.01, 0.02 or a range composed of any two of them, M is selected from manganese and / or aluminum, N is selected from one or more of aluminum, zirconium, tungsten, titanium, magnesium, calcium, boron, strontium, niobium, molybdenum, tantalum, which can further improve the capacity of the battery and reduce the degree of cation mixing, improve the structural stability of the ternary positive electrode material.

[0052] In some embodiments, the ternary positive electrode material includes a nickel-cobalt-manganese ternary material and / or a nickel-cobalt-aluminum ternary material.

[0053] The embodiment of the present application provides a preparation method of the ternary positive electrode material, including the following steps: performing a co-precipitation reaction on a mixed solution including a metal source and a solvent to obtain a ternary material precursor, the co-precipitation reaction being performed at a temperature of 50-70°C; and performing a sintering treatment on a mixture including the ternary material precursor and a lithium source to obtain the ternary positive electrode material; wherein the ternary material precursor includes secondary particles DB, and at least part of the primary particles EB in the secondary particles DB extend from the center of the secondary particles DB to the surface of the secondary particles DB.

[0054] In the above preparation process, the ternary material precursor is used, and in the secondary particles DB of the ternary material precursor, at least part of the primary particles EB extend from the center of the secondary particles DB to the surface of the secondary particles DB. During the sintering treatment, lithium elements provided by the lithium source are embedded into the crystal lattice of the ternary material precursor, and a layered structure ternary positive electrode material is formed. At the same time, the ternary positive electrode material maintains the primary particle distribution structure that at least part of the primary particles in the secondary particles extend from the center of the secondary particles to the surface of the secondary particles, that is, at least part of the primary particles EA in the secondary particles EA obtained by the ternary positive electrode material extend from the center of the secondary particles DA to the surface of the secondary particles DA.

[0055] Specifically, the ternary material precursor can be a hydroxide containing nickel (Ni), cobalt (Co) and M elements, and its chemical formula can be represented as Ni a Co b M 1-a-b (OH)2, wherein 0.6≤a≤0.8, 0.1≤b≤0.2, and M is selected from manganese (Mn) and / or aluminum (Al).

[0056] For example, the ternary material precursor can be Ni a Co b Mn 1-a-b (OH)2, and at this time, the ternary positive electrode material obtained is a nickel-cobalt-manganese ternary material (NCM, lithium nickel cobalt manganese oxide).

[0057] For example, the ternary material precursor can be Ni a Co b Al 1-a-b (OH)2, and the prepared ternary positive electrode material is a nickel-cobalt-aluminum ternary material (NCA, lithium nickel cobalt aluminate).

[0058] Specifically, the lithium source can provide lithium elements for the ternary positive electrode material, and the amount of the lithium source can be adjusted according to the stoichiometric ratio of the chemical formula of the ternary positive electrode material to be prepared, and no particular limitation is made. Generally, to compensate for the loss of lithium elements in the sintering process, the amount of lithium source added usually needs to be 5% to 10% in excess.

[0059] Specifically, the lithium source can include lithium hydroxide and / or lithium carbonate, and in specific implementation, the lithium hydroxide used can be hydrated lithium hydroxide (LiOH H2O).

[0060] In some embodiments, the ternary material precursor and LiOH H2O can be mixed in a mass ratio of (2:1) to (2.2:1) to prepare a mixture.

[0061] Specifically, the mixing process of the ternary material precursor and the lithium source such as LiOH H2O can be carried out in a ball mill, which helps to mix uniformly and improve the uniformity of the subsequent high-temperature sintering process.

[0062] In some embodiments, the sintering process includes: after the first sintering process of the mixture, the second sintering process is carried out to prepare the ternary positive electrode material, which can further remove possible organic impurities in the mixture.

[0063] In some embodiments, the temperature of the first sintering process can be 500°C to 550°C, for example, the temperature can be 500°C, 510°C, 520°C, 530°C, 540°C, 550°C or a range formed by any two of them. The temperature of the first sintering process is not less than 500°C, which is more conducive to effectively removing possible organic impurities in the mixture, promoting the preliminary reaction of the ternary material precursor and the lithium source, and facilitating the uniform reaction of the ternary material and the lithium source in the subsequent second sintering process; the temperature of the first sintering process is not greater than 550°C, which can avoid the volatilization of the lithium source and the agglomeration of the ternary material precursor, affecting the particle size of the primary particles in the ternary positive electrode material, and at the same time, avoiding the destruction of the structure of the ternary precursor extending in the radial direction, affecting the rate performance of the battery. Therefore, the temperature of the first sintering process is 500°C to 550°C, which can further remove impurities in the mixture, promote the preliminary reaction of the ternary material precursor and the lithium source, and at the same time, avoid the volatilization of the lithium source and the agglomeration of the ternary material precursor.

[0064] In some embodiments, the first sintering treatment can be performed for 4-6 hours, for example, for 4 hours, 5 hours, 6 hours, or any range defined by any two of the foregoing. The first sintering treatment for no less than 4 hours can further remove impurities in the mixture, promote activation of the ternary material precursor and the lithium source, and the first sintering treatment for no more than 6 hours can improve the preparation efficiency of the ternary positive electrode material and reduce the preparation cost of the ternary positive electrode material. Therefore, the first sintering treatment for 4-6 hours can further promote activation of the ternary material precursor and the lithium source, remove impurities in the mixture, improve the preparation efficiency of the ternary positive electrode material, and reduce the preparation cost of the ternary positive electrode material.

[0065] In some embodiments, the second sintering treatment can be performed at a temperature of 700-800 degrees Celsius, for example, at a temperature of 700 degrees Celsius, 730 degrees Celsius, 750 degrees Celsius, 760 degrees Celsius, 800 degrees Celsius, or any range defined by any two of the foregoing. The second sintering treatment at a temperature of no less than 700 degrees Celsius can further reduce the degree of Li + / Ni + cation mixing, improve the integrity of the layered structure of the ternary positive electrode material, and improve the I （003） / I （104） crystallinity of the primary particles EA, and the second sintering treatment at a temperature of no more than 800 degrees Celsius can avoid excessive growth of the crystals, possible "local collapse" of the layered structure (Li⁺excessive extraction leading to distortion of the layered structure), excessive sintering and growth of the primary particles EA, and reduction of the structural stability of the ternary positive electrode material, and at the same time, avoid destroying the structure in which at least part of the primary particles EA in the secondary particles DA extend from the center of the secondary particles DA to the surface of the secondary particles DA. Therefore, the second sintering treatment at a temperature of 700-800 degrees Celsius can further reduce the degree of Li + / Ni + cation mixing, improve the structural stability of the ternary positive electrode material, and improve the ion conductivity and other properties of the ternary positive electrode material.

[0066] In some embodiments, the second sintering treatment can be performed for 10-14 hours, for example, for 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, or any range defined by any two of the foregoing. The second sintering treatment for no less than 10 hours can allow the ternary material precursor and the lithium source to fully react, improve the integrity of the layered structure of the ternary positive electrode material, and the second sintering treatment for no more than 10 hours can avoid excessive growth and agglomeration of the primary particles EA, which can lengthen the lithium ion diffusion path. Therefore, the second sintering treatment for 10-14 hours can further improve the integrity of the layered structure of the ternary positive electrode material, shorten the lithium ion diffusion path, and improve the cycle stability and rate performance of the battery.

[0067] In some embodiments, the sintered mixture is cooled to room temperature, and then subjected to crushing and sieving to obtain the ternary cathode material with a particle size of 3-5 μm.

[0068] The crushing and sieving are conventional processes in the art and are not particularly limited.

[0069] In some embodiments, the above mixture further comprises a chelating agent and a precipitant, and thus the preparation of the ternary material precursor comprises: subjecting the mixture comprising the metal source, the precipitant, the chelating agent and the solvent to a co-precipitation reaction to obtain the ternary material precursor.

[0070] In the above preparation process, the metal source is used to provide the required Ni, Co, M and other metal elements for the ternary cathode material. The metal source can specifically comprise a metal salt, and the metal salt can comprise a sulfate salt, for example, one or more of nickel sulfate, cobalt sulfate and manganese sulfate.

[0071] In specific implementations, the above metal salt can be a hydrate, for example, one or more of nickel sulfate hydrate (NiSO4·6H2O), cobalt sulfate hydrate (CoSO4·7H2O) and manganese sulfate hydrate (MnSO4·5H2O).

[0072] In specific implementations, the amount of each metal salt can be adjusted according to the stoichiometric ratio of the chemical formula of the ternary cathode material to be prepared, for example, the molar ratio of nickel sulfate hydrate (NiSO4·6H2O), cobalt sulfate hydrate (CoSO4·7H2O) and manganese sulfate hydrate (MnSO4·5H2O) can be (8:1:1) to (6:2:2).

[0073] In specific implementations, the metal source can be dissolved in water to obtain a metal source aqueous solution, and then the metal source aqueous solution, the precipitant, the chelating agent and other components are mixed to obtain the above mixture, and the mixture is subjected to a co-precipitation reaction to obtain the ternary material precursor.

[0074] In some embodiments, the concentration of the metal source aqueous solution can be 1.0-2.2 mol / L.

[0075] In the above preparation process, the precipitant can comprise one or more of sodium hydroxide (NaOH), potassium hydroxide, sodium carbonate and potassium carbonate, which is more conducive to the formation of hydroxide precipitates containing Ni, Co and M elements and the formation of the ternary material precursor.

[0076] In specific implementations, the precipitant can be dissolved in water to obtain a precipitant aqueous solution, for example, sodium hydroxide can be dissolved in water to obtain a sodium hydroxide aqueous solution. Then the precipitant aqueous solution, the metal source aqueous solution, the chelating agent and other components are mixed to obtain the above mixture.

[0077] In some embodiments, the concentration of the aqueous solution of the precipitant is 1.5 mol / L to 3 mol / L, for example, can be 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, 3 mol / L or a range consisting of any two of them.

[0078] In the above preparation process, the concentration of the chelating agent in the mixed solution can be 0.8 mol / L to 2 mol / L, for example, can be 0.8 mol / L, 1.0 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2 mol / L or a range consisting of any two of them, which is more conducive to controlling the crystal growth direction of the ternary material precursor and promoting the growth of primary particles.

[0079] In some embodiments, the chelating agent can act as a stabilizer and complexing agent in the coprecipitation reaction, controlling the release rate of Ni, Co, M metal ions by forming stable metal ammonia complexes.

[0080] In some embodiments, the chelating agent includes one or more of ammonia, ammonium acetate, and ammonium sulfate, wherein the ammonia can further provide alkaline conditions for the coprecipitation reaction.

[0081] In some embodiments, the pH of the mixed solution is 10 to 12, for example, can be 10, 11, 12 or a range consisting of any two of them, and the moderate alkaline environment with a pH of 10 to 12 is more conducive to the generation and precipitation of hydroxides of Ni, Co, M elements.

[0082] In the above preparation process, the solvent in the mixed solution can include water.

[0083] In some embodiments, the coprecipitation reaction is carried out under stirring, and during the coprecipitation reaction, the mixed solution is stirred by an impeller, and the outer edge speed of the impeller can be 600 rpm to 1200 rpm, for example, can be 600 rpm, 800 rpm, 900 rpm, 1000 rpm, 1200 rpm or a range consisting of any two of them. The outer edge speed of the impeller is not less than 600 rpm, which can provide strong mechanical stirring and uniform coprecipitation reaction environment, and can ensure that the mixed solution has a good mixing state, which is more conducive to preventing further agglomeration of secondary particles DB due to local supersaturation, avoiding the increase of active ion (lithium ion) migration path, and reducing the ionic conductivity of the ternary material precursor. The outer edge speed of the impeller is not greater than 1200 rpm, which can further regulate the crystal growth direction of the ternary material precursor and promote the growth of primary particles EB. Therefore, the outer edge speed of the impeller is 600-1200 rpm, which is more conducive to regulating the morphology and structure of the ternary material precursor and improving the ionic conductivity of the ternary material precursor.

[0084] In the embodiments of the present application, the temperature of the co-precipitation reaction is 50-70°C, for example, the temperature can be 50°C, 55°C, 60°C, 65°C, 70°C or a range formed by any two of them. The temperature of the co-precipitation reaction is not less than 50°C, which is more conducive to regulating the hydrolysis rate of metal ions, controlling the proportion of Ni, Co and M elements in the ternary material precursor, facilitating the growth of primary particles EB, and the temperature of the co-precipitation reaction is not more than 70°C, the crystal is easy to "overgrow", and lattice distortion occurs in some areas, which is not conducive to improving the stability of the layered structure of the ternary positive electrode material. Therefore, the temperature of the co-precipitation reaction is 50-70°C, which can further optimize the kinetic conditions of the co-precipitation reaction and improve the stability of the structure of the ternary material precursor.

[0085] In some embodiments, the co-precipitation reaction time is 5-12h, for example, it can be 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h or a range formed by any two of them. The co-precipitation reaction time is not less than 5h, which helps the co-precipitation reaction to be more sufficient, and the co-precipitation reaction time is not more than 12h, which is more conducive to avoiding the overgrowth of primary particle EB. Therefore, the co-precipitation reaction time is 5-12h, which can further optimize the co-precipitation reaction and avoid the overgrowth of primary particle EB.

[0086] Specifically, the co-precipitation reaction can be carried out in an inert atmosphere, for example, including nitrogen (N2), to reduce the occurrence of oxidation reaction. In specific implementation, the co-precipitation reaction can be carried out in a continuous stirred tank reactor, and the inert atmosphere is maintained in the reactor.

[0087] Exemplarily, the co-precipitation reaction can be carried out under N2 atmosphere.

[0088] Specifically, after the completion of the co-precipitation reaction, the precipitate is taken out, washed to remove impurity ions in the mixed solution on the surface of the precipitate. Then, it is filtered and dried in a vacuum drying box to remove water, and the drying temperature can be 50-80°C, and the drying time can be 8-12h, to obtain the ternary material precursor.

[0089] In some embodiments, the preparation process of the ternary positive electrode material can include the following steps:

[0090] S1: Dissolve the metal salt in water to obtain an aqueous solution of the metal salt. Pump this solution into a stirred reactor (model: turbine stirrer, HZ300L reactor) under nitrogen protection. Simultaneously, add an aqueous solution of the precipitant and a chelating agent to the stirred reactor to obtain a mixture. Perform a co-precipitation reaction on this mixture. Specifically, the growth direction of the ternary material precursor crystals and the growth of primary particles (EB) can be controlled by adjusting the concentration of the chelating agent and the stirring speed (impeller outer edge speed) of the stirred reactor, thereby obtaining the precipitate.

[0091] S2: The above precipitate is washed and dried to obtain a ternary material precursor;

[0092] S3: The ternary material precursor is mixed with the lithium source to prepare a mixture, and the mixture is subjected to a first sintering treatment and a second sintering treatment to obtain the ternary cathode material.

[0093] S4: Cool, crush and sieve the above ternary cathode material to control the particle size of the ternary cathode material.

[0094] In practice, the shape and particle size of the primary particles EA in the secondary particles of the ternary cathode material can be controlled by adjusting the concentration of the chelating agent and the outer edge speed of the impeller.

[0095] This invention provides a positive electrode sheet, including a positive current collector and a positive active layer located on at least one side of the positive current collector. The positive active layer includes the ternary positive electrode material described above or a ternary positive electrode material prepared according to the preparation method described above.

[0096] For example, the positive electrode includes a positive current collector and a positive active layer located on at least one side of the positive current collector. Specifically, the positive active layer can be disposed on one side surface of the positive current collector, or the positive active layer can be disposed on both the positive and negative surfaces of the positive current collector.

[0097] The positive current collector can be a conventional positive current collector in the art, for example, the positive current collector may include aluminum foil, but is not limited thereto.

[0098] In some embodiments, the positive electrode active layer may further include a solid electrolyte, which may include a sulfide solid electrolyte. For example, the sulfide solid electrolyte in the positive electrode active layer may include Li6PS5Cl, Li... 6-z PS 5-z-x O x Y 1+z One or more of the following, wherein 0≤x≤0.3, 0.3≤z≤0.7, and Y includes Cl and / or Br.

[0099] Specifically, Li 6-z PS5-z-x O x Y 1+z Li 6-z PS 5-z-x O x Cl 1+z Li 6-z PS 5-z-x O x Br 1+z wherein 0≤x≤0.3, 0.3≤z≤0.7.

[0100] In some embodiments, the mass ratio of the ternary cathode material to the solid-state electrolyte is (8:2)~(9:1), for example, can be (8:2), (8.2:1.8), (8.4:1.6), (8.6:1.4), (8.8:1.2), (9:1) or a range consisting of any two of them, which can further shorten the transmission path of active ions in the cathode active layer, improve the utilization rate of the ternary cathode material, and improve the capacity, rate performance and cycle stability of the battery.

[0101] In addition, the cathode coating can also include a conductive agent and / or a binder, both of which can be conventional materials in the art. For example, the conductive agent can include one or more of carbon black, conductive graphite, conductive carbon fiber, carbon nanotubes (CNT), acetylene black, graphene, ketjen black, carbon fiber, and the binder can include one or more of styrene butadiene rubber (SBR), butyl rubber (NBR), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, oxirane-containing polymers, polyvinyl pyrrolidone, polyurethane, etc.

[0102] Specifically, the ternary cathode material and the solid-state electrolyte can be mixed, a solvent is added, the solvent includes one or more of anisole, ethanol, isopropanol, N-methyl-2-pyrrolidone (NMP), dichloromethane or diethyl ether, then a binder and a conductive agent are added, the cathode slurry is prepared by mechanical stirring and mixing, the cathode slurry is coated on at least one side of the cathode current collector, and the cathode sheet is prepared after drying and rolling, wherein the drying and rolling are conventional operations in the art, and are not particularly limited.

[0103] In particular implementation, the solvent used can be anhydrous solvent, for example, anhydrous ethanol is used, which can further avoid possible side reactions or degradation of the ternary cathode material.

[0104] The embodiment of the present application provides a single battery including the above-mentioned cathode sheet, which has advantages corresponding to the above-mentioned cathode sheet, and will not be described again.

[0105] In the embodiments of the present application, the single battery includes a solid-state battery, and specifically can be an NCM solid-state battery or an NCA solid-state battery.

[0106] In general, the battery further includes a solid-state electrolyte layer and a negative electrode sheet, and the solid-state electrolyte layer is located between the positive electrode sheet and the negative electrode sheet to separate the positive electrode sheet and the negative electrode sheet.

[0107] In the embodiments of the present application, the solid-state electrolyte layer and the negative electrode sheet can be conventional in the art, and no specific limitation is made thereto.

[0108] In general, the solid-state electrolyte layer can include a solid-state electrolyte and a binder, and the mass percentage of the solid-state electrolyte in the solid-state electrolyte layer (i.e., the proportion of the mass of the solid-state electrolyte to the total mass of the solid-state electrolyte layer) can be 90% to 100%, for example, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, or a range formed by any two of them. The mass percentage of the binder in the solid-state electrolyte layer (i.e., the proportion of the mass of the binder to the total mass of the solid-state electrolyte layer) can be 0 to 10%, for example, 0, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a range formed by any two of them.

[0109] In the embodiments of the present application, the solid-state electrolyte in the solid-state electrolyte layer can include a sulfide solid-state electrolyte and / or a halide solid-state electrolyte, the sulfide solid-state electrolyte can include Li6PS5Cl, Li 10 GeP2S 12 , Li 5.5 PS5Cl 1.5 , and the halide solid-state electrolyte can include a chloride solid-state electrolyte, and the chloride solid-state electrolyte can include Li 1.75 ZrCl 4.75 O 0.5 . The binder in the solid-state electrolyte layer can be a conventional binder material in the art, for example, including one or more of butyl rubber (NBR), PVDF, SBR, hydrogenated nitrile rubber (HNBR), and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP).

[0110] Specifically, the solid-state electrolyte layer can be arranged on the surface of the negative electrode sheet, and specifically can be coated on the surface of the negative electrode active layer away from the negative electrode active current collector.

[0111] Illustratively, the solid-state electrolyte can be mixed with the binder, added to a solvent, for example, including toluene, to prepare a solid-state electrolyte layer slurry, and the slurry can be coated on the negative electrode sheet, dried, and the solid-state electrolyte layer is formed on the negative electrode sheet.

[0112] In addition, the negative electrode sheet can include a negative electrode current collector, and a negative electrode active layer present on at least one side surface of the negative electrode current collector, and in particular, the negative electrode active layer can be provided on one side surface of the negative electrode current collector, or the negative electrode active layer can be provided on both side surfaces of the negative electrode current collector.

[0113] In particular, the negative electrode current collector can be a conventional negative electrode current collector in the art, for example, the negative electrode current collector can include a copper foil and / or a carbon-coated copper foil, but is not limited thereto.

[0114] In particular, the negative electrode active layer can include a negative electrode active material, and the negative electrode active material can be a conventional negative electrode active material in the art, for example, the negative electrode active material can include one or more of silicon powder, hard carbon, graphite, silicon-based material, and lithium metal material.

[0115] In addition, the negative electrode active layer can further include a solid-state electrolyte, and the solid-state electrolyte in the negative electrode active layer can include a sulfide solid-state electrolyte and / or a halide solid-state electrolyte. In particular, the sulfide solid-state electrolyte can include one or more of Li6PS5Cl, Li 10 GeP2S 12 , Li 5.5 PS5Cl 1.5 , and the halide solid-state electrolyte can include a chloride solid-state electrolyte, and the chloride solid-state electrolyte can include one or more of Li 1.75 ZrCl 4.75 O 0.5 In particular, the solid-state electrolyte in the negative electrode active layer can be the same as or different from the solid-state electrolyte in the solid-state electrolyte layer.

[0116] In particular, the solid-state electrolyte in any two of the positive electrode sheet, the negative electrode sheet, and the solid-state electrolyte layer can be the same or different.

[0117] In addition, the negative electrode active layer can further include a conductive agent and / or a binder, and both the conductive agent and the binder can be conventional materials in the art. For example, the conductive agent can include one or more of carbon black, carbon nanotube (CNT), acetylene black, graphene, ketjen black, carbon fiber, and conductive carbon fiber. The binder can include one or more of carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, oxirane-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide imide, polyvinyl alcohol, and sodium polyacrylate.

[0118] In particular, the negative electrode active material and the solid-state electrolyte can be mixed, and the conductive agent and the binder can be added to a solvent, for example, the solvent can include toluene, and the mixture can be stirred to form a stable and uniform negative electrode slurry. The negative electrode slurry can be uniformly coated on at least one side surface of the negative electrode current collector, and the negative electrode sheet can be obtained by drying and rolling the negative electrode slurry, and both the drying and the rolling can be conventional operations in the art, and are not particularly limited.

[0119] In the embodiments of the present application, the battery can be prepared by conventional methods in the art, and no specific limitation is made thereto.

[0120] The embodiments of the present application provide a battery pack comprising at least two single batteries as described above, which has the advantages corresponding to the positive plate as described above, and no further description is made.

[0121] Generally, the battery pack comprises a plurality of batteries as described above, which are connected to form the battery pack as single batteries. Among them, the batteries can be electrically connected by conventional methods in the art, such as series connection, parallel connection, or mixed connection comprising both of the connection modes, and no specific limitation is made thereto.

[0122] The embodiments of the present application provide a power consuming device comprising the battery as described above or the battery pack as described above, which has the advantages corresponding to the positive plate as described above, and no further description is made.

[0123] The power consuming device of the embodiments of the present application can be a conventional power consuming device in the art, such as a power device (e.g., an electric vehicle, an electric car), an electronic device (e.g., a mobile phone, a tablet computer, a notebook computer, a digital camera, etc.), a wearable device (e.g., a watch, a bracelet, a VR glasses, etc.), an energy storage power station, etc., and no specific limitation is made thereto.

[0124] The present application is further described below through specific embodiments.

[0125] Embodiment 1

[0126] 1. Preparation of the positive material

[0127] S1: In a 250L reaction kettle, a metal salt aqueous solution (the total concentration of metal salts in the metal salt aqueous solution is 1.5 mol / L) comprising NiSO4·6H2O, CoSO4·7H2O and MnSO4·5H2O in a molar ratio of 8:1:1 is pumped into the stirring reaction kettle under nitrogen protection, the flow rate is 11.6 mL / s, and an aqueous solution of NaOH (the concentration is 2 mol / L) and ammonia water (the concentration is 1.5 mol / L) are added to the stirring reaction kettle at the same time to obtain a mixed solution, wherein the flow rate of the aqueous solution of NaOH is 19.1 mL / s, the flow rate of the ammonia water is 6.1 mL / s, and the pH value of the mixed solution is 11. The mixed solution is subjected to a co-precipitation reaction to prepare a precipitate; wherein the temperature of the co-precipitation reaction is 60°C, the time is 6h, and the impeller outer edge speed of the stirring reaction kettle during the co-precipitation reaction is 900rmp;

[0128] S2: The precipitate is washed and then dried at 60°C for 10h to prepare a ternary material precursor;

[0129] S3: The ternary material precursor and lithium source (LiOH H2O) are mixed in a mass ratio of 2.1:1 to prepare a mixture, the mixture is subjected to first sintering treatment, the first sintering treatment temperature is 530°C, and the time is 6h; then the second sintering treatment is performed, the second sintering treatment temperature is 750°C, and the time is 12h, to obtain the ternary positive electrode material;

[0130] S4: The ternary positive electrode material is cooled, crushed and sieved to obtain a ternary positive electrode material with a particle size of 3μm.

[0131] 2. Preparation of the positive electrode sheet

[0132] Under an argon atmosphere, the ternary positive electrode material prepared above and Li6PS5Cl are mixed in a mass ratio of 8:2 using anisole as a solvent, then 0.5w% of NBR and 1w% of conductive carbon fiber are added, wherein 0.5w% of NBR means that NBR accounts for 0.5% of the total mass of the positive electrode active layer, and 1w% of conductive carbon fiber means that conductive carbon fiber accounts for 1% of the total mass of the positive electrode active layer. The mixture is prepared into a positive electrode slurry, then the positive electrode slurry is coated on the surfaces of both sides of an aluminum foil, dried at a temperature of 373K, and then pressed into a sheet by a roller press to form a positive electrode active layer, thereby obtaining a positive electrode sheet.

[0133] 3. Preparation of the negative electrode sheet

[0134] Under an argon atmosphere, silicon powder and hard carbon mixed in a mass ratio of 1:2 are used as a negative electrode active material, the negative electrode active material and Li6PS5Cl solid-state electrolyte are mixed in a mass ratio of 8:1, and 1w% of conductive carbon fiber and 3w% of SBR are added to toluene, wherein 3w% of SBR means that SBR accounts for 0.5% of the total mass of the negative electrode active layer, and 1w% of conductive carbon fiber means that conductive carbon fiber accounts for 1% of the total mass of the negative electrode active layer. The mixture is stirred in a blender to form a stable and uniform negative electrode slurry, the negative electrode slurry is uniformly coated on the surfaces of both sides of a copper foil, dried at a temperature of 373K, and then pressed into a sheet by a roller press to form a negative electrode active layer, thereby obtaining a negative electrode sheet.

[0135] 4. Preparation of the solid-state electrolyte layer

[0136] Under an argon atmosphere, Li6PS5Cl and NBR are mixed in a mass ratio of 80:20 and added to a toluene solution to obtain a solid-state electrolyte layer slurry, and the slurry is coated on the negative electrode sheet and dried at a temperature of 373K to form a solid-state electrolyte layer with a thickness of 50 microns on the negative electrode sheet.

[0137] 5. Preparation of the battery

[0138] The positive electrode sheet and the negative electrode sheet with the solid-state electrolyte layer were placed in a tablet press under argon protection, and then pressed at 150 degrees Celsius and 1.5 MPa. After vacuum sealing with an aluminum plastic film, the soft package battery was obtained by pressing in a static press at 25 MPa for 250 s.

[0139] Examples 2-15: Different from Example 1, the particle size of the ternary positive electrode material, the molar ratio of O2, NiSO4·6H2O, CoSO4·7H2O and MnSO4·5H2O, the concentration of the chelating agent, the pH value of the mixed solution, the outer edge speed of the impeller, the temperature and time of the co-precipitation reaction, and the mass ratio of the ternary positive electrode material to the solid-state electrolyte were different, as shown in Tables 1 and 2. The remaining steps and conditions were the same as in the example. a Co b M 1-a-b-c N c O2, NiSO4·6H2O, CoSO4·7H2O and MnSO4·5H2O, the concentration of the chelating agent, the pH value of the mixed solution, the outer edge speed of the impeller, the temperature and time of the co-precipitation reaction, and the mass ratio of the ternary positive electrode material to the solid-state electrolyte were different, as shown in Tables 1 and 2. The remaining steps and conditions were the same as in the example.

[0140] Comparative Example 1: Different from Example 1, the ammonia water concentration in step S1 was adjusted to 0.3 mol / L to prepare a mixed solution with a pH value of 9.5. The co-precipitation reaction was carried out in an air environment, wherein the temperature of the co-precipitation reaction was 25℃, the time of the co-precipitation reaction was 4h, and the outer edge speed of the impeller of the reactor was 300rpm.

[0141] In step S3, no first sintering treatment was performed, and a second sintering treatment was directly performed in an air atmosphere, wherein the temperature of the second sintering treatment was 500℃, and the time of the second sintering treatment was 8h, to prepare a randomly polymerized ternary positive electrode material.

[0142] The remaining steps and conditions were the same as in the example, as shown in Tables 1 and 2.

[0143] Comparative Example 2: Different from Example 1, the temperature of the co-precipitation reaction in step S1 was 40℃, the time of the co-precipitation reaction was 5h, the outer edge speed of the impeller of the stirring reactor was 300rmp, the temperature of the second sintering treatment in step S3 was 650℃, and the time of the second sintering treatment was 8h. The remaining steps and conditions were the same as in Example 1, as shown in Tables 1 and 2.

[0144] The number ratio of the primary particles EA whose center extends to the surface of the secondary particles DA, the I （003） / I （104） The particle size test method of the ternary positive electrode material was as described above, and the test data of the examples and comparative examples were summarized in Table 1.

[0145] The ternary material precursor, the ternary positive electrode material, and the battery in the examples and comparative examples were tested by the following processes, and the test results are shown in Tables 1 and 3:

[0146] (1) Scanning Electron Microscopy (SEM) Test: The ternary material precursor and ternary cathode material prepared above were observed by SEM. The test results showed that in the ternary material precursors of Examples 1-15, the primary particle EB in the secondary particle DB extended from the center of the secondary particle DB to the surface of the secondary particle DB. Correspondingly, in the ternary cathode material, the primary particle EA in the secondary particle DA extended from the center of the secondary particle DA to the surface of the secondary particle DA. The following uses the test results of the ternary material precursor and ternary cathode material in Example 1 as an example. The front view of the ternary material precursor in Example 1 is as follows. Figure 2 As shown in b; the front view of the ternary cathode material in Example 1 is shown in Figure 1. Figure 3 As shown in b1; the cross-sectional view of the ternary cathode material in Example 1 is shown in Figure 1. Figure 3 As shown in b2.

[0147] In the ternary precursors of Comparative Examples 1 and 2, a small number of primary particles EB extend from the center of secondary particles DB to the surface of secondary particles DB (far fewer than the proportion of primary particles EA extending from the center of secondary particles DA to the surface of secondary particles DA in the examples). Correspondingly, the proportion of primary particles EA extending from the center of secondary particles DA to the surface of secondary particles DA in the prepared ternary cathode material is low. Taking the test results of the ternary precursor and ternary cathode material in Comparative Example 1 as an example, the front view of the ternary precursor in Comparative Example 1 is as follows. Figure 2 As shown in Figure a, the front view of the ternary cathode material in Comparative Example 1 is as follows. Figure 3 As shown in a1, the cross-sectional view of the ternary cathode material in Comparative Example 1 is as follows. Figure 3 As shown in a2.

[0148] Take the battery prepared above, cycle it 200 times, then disassemble the battery and remove the positive electrode. Observe the cross-sectional image of the positive electrode using SEM, as shown below. Figure 4 As shown in Figure a, it is a cross-sectional view of the positive electrode in Comparative Example 1, as follows. Figure 4 Figure b shows a cross-sectional view of the positive electrode in Example 1.

[0149] (2) Test method for the exposure ratio of (010) crystal plane of ternary cathode material: Specifically, the ternary cathode materials of each embodiment and comparative example can be tested by electron backscatter diffraction (EBSD). The test results show that the exposure ratio of (010) crystal plane of ternary cathode material in each embodiment is greater than or equal to 82%, while the exposure ratio of (010) crystal plane of ternary cathode material in each comparative example is less than 82%. The results are shown in Table 1.

[0150] (3) Battery rate performance test: Take the batteries prepared above and perform constant current charge and discharge cycle test on the rate performance. First, charge the batteries to 4V at a small rate of 0.05C. Then, discharge the batteries made of the positive electrode materials in the examples and comparative examples to 2.8V at 0.1C and 1C respectively. Calculate the 1C discharge capacity / 0.1C discharge capacity × 100%, which is the rate performance of the battery, as shown in Table 3.

[0151] (4) Cyclic stability test of the battery: Take the battery prepared above, charge it at 0.1C and discharge it at 1C (charge it at 0.1C to 4.35V and discharge it at 1C to 2.8V). Record the first discharge capacity as Q1. After 300 cycles, record the discharge capacity of the 300th cycle as Q2. The cycle stability of the battery, i.e. the cycle retention rate = Q2 / Q1×100%, is shown in Table 3.

[0152] Table 1. Parameters and preparation parameters of ternary cathode materials

[0153]

[0154] Table 2. Preparation parameters of ternary cathode materials and cathode sheets

[0155]

[0156] Table 3 Battery Performance

[0157]

[0158] Compared to Comparative Examples 1-2, the ternary cathode materials in Examples 1-15 include secondary particles DA, at least a portion of the primary particles EA in the secondary particles DA extend from the center of the secondary particles DA to the surface of the secondary particles DA, and the exposed ratio of the (010) crystal plane of the ternary cathode material is greater than or equal to 82%, which can improve the structural stability and ionic conductivity of the ternary cathode material, thereby improving the rate performance and cycle stability of the battery and other electrochemical performance.

[0159] contrast Figure 1 a1 and Figure 1 b1 shows that the cathode material particles in Comparative Example 1 and Example 1 both initially have good contact, but compared to... Figure 1 a2 and Figure 1 After 200 cycles, the surface contact of the cathode material particles in Comparative Example 1 was insufficient, while the ternary cathode material particles in Example 1 still had good contact.

[0160] contrast Figure 2 a and Figure 2 b, Figure 3 a1 and Figure 3 b1,Figure 3 a2 and Figure 3 In b2, it can be observed that the primary particles EA in the ternary cathode material of Example 1 extend from the center of the secondary particles DA to the surface of the secondary particles DA. In the front view, it can be observed that the primary particles EA are tightly adhered to each other. In the cross-sectional view, it can be observed that the primary particles EA extend from the center of the secondary particles DA to the surface of the secondary particles DA. In contrast, the cathode material particles in Comparative Example 1 are randomly aggregated.

[0161] contrast Figure 4 a and Figure 4 As can be seen from b, the cathode material 1 particles in Comparative Example 1 break and form cracks during cycling, while the ternary cathode material 2 in Example 1 has good contact with the Li6PS5Cl solid electrolyte 3.

[0162] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A ternary cathode material, characterized in that, The ternary cathode material includes secondary particles DA, the secondary particles DA includes a plurality of primary particles EA, and at least a portion of the primary particles EA in the secondary particles DA extends from the center of the secondary particles DA to the surface of the secondary particles DA. The exposed ratio of the (010) crystal plane of the ternary cathode material is greater than or equal to 82%.

2. The ternary cathode material according to claim 1, characterized in that, In the secondary particle DA, the proportion of the primary particle EA extending from the center of the secondary particle DA to the surface of the secondary particle DA is greater than or equal to 90%.

3. The ternary cathode material according to claim 1 or 2, characterized in that, The exposed (010) crystal plane of the ternary cathode material accounts for 82% to 98%; And / or, the particle size of the ternary cathode material is 3μm~5μm.

4. The ternary cathode material according to any one of claims 1-3, characterized in that, In the X-ray diffraction test results of the ternary cathode material, the peak intensity I of the (003) diffraction peak is... （003） The peak intensity I of the (104) diffraction peak （104) The ratio is 1.27~1.

33.

5. The ternary cathode material according to any one of claims 1-4, characterized in that, The primary particles EA include nanosheets.

6. The ternary cathode material according to any one of claims 1-5, characterized in that, The chemical formula of the ternary cathode material is shown in Formula 1: LiNi a Co b M 1-a-b-c N c O2 Formula 1, Wherein, 0.6≤a≤0.8, 0.1≤b≤0.2, 0≤c≤0.1, M is selected from manganese and / or aluminum, and N is selected from one or more of aluminum, zirconium, tungsten, titanium, magnesium, calcium, boron, strontium, niobium, molybdenum, and tantalum.

7. A method for preparing a ternary cathode material according to any one of claims 1-6, characterized in that, Includes the following steps: A ternary material precursor is prepared by co-precipitation reaction of a mixture including a metal source and a solvent, wherein the temperature of the co-precipitation reaction is 50℃~70℃. The ternary cathode material is prepared by sintering a mixture of a ternary material precursor and a lithium source; wherein the ternary material precursor includes secondary particles DB, and at least a portion of the primary particles EB in the secondary particles DB extends from the center of the secondary particles DB to the surface of the secondary particles DB.

8. The method for preparing the ternary cathode material according to claim 7, characterized in that, The mixture also includes a chelating agent, and the concentration of the chelating agent in the mixture is 0.8 mol / L to 2 mol / L.

9. The method for preparing the ternary cathode material according to claim 8, characterized in that, The chelating agent includes ammonia; And / or, the pH of the mixture is 10-12; And / or, during the coprecipitation reaction, the mixture is stirred by an impeller, the outer edge speed of which is 600 rpm to 1200 rpm; And / or, the coprecipitation reaction takes 5 to 12 hours.

10. The method for preparing the ternary cathode material according to claim 7, characterized in that, The sintering process includes: performing a first sintering treatment on the mixture and then performing a second sintering treatment to obtain the ternary cathode material; The temperature of the first sintering treatment is 500℃~550℃, and the time is 4h~6h. The second sintering treatment is performed at a temperature of 700℃~800℃ for 10h~14h.

11. A positive electrode plate, characterized in that, It includes a positive current collector and a positive active layer located on at least one side of the positive current collector, wherein the positive active layer includes the ternary positive electrode material according to any one of claims 1-6 or the ternary positive electrode material prepared according to the preparation method according to any one of claims 7-10.

12. The positive electrode sheet according to claim 11, characterized in that, The positive electrode active layer also includes a solid electrolyte; Preferably, the mass ratio of the ternary cathode material to the solid electrolyte is (8:2) to (9:1).

13. A battery, characterized in that, Includes the positive electrode sheet as described in claim 11 or 12, wherein the battery is either a single cell or a battery pack.

14. An electrical appliance, characterized in that, Includes the battery as described in claim 13.

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