Ternary positive electrode material, preparation method thereof and electrochemical device

Abstract

The invention discloses a ternary positive electrode material, a preparation method thereof and an electrochemical device, the ternary positive electrode material provided by the embodiment of the invention is a single-crystal ternary positive electrode material, the particle size span distribution span of the ternary positive electrode material is equal to (D90-D10) / D50, span is 0.8-1.1, and the average circularity R of the ternary positive electrode material is greater than or equal to 70%. The single-crystal ternary positive electrode material has good monodispersity and circularity, on one hand, the compaction density of the ternary positive electrode material can be improved, on the other hand, poor conductivity of a local area can be reduced, the transmission rate of electrons and lithium ions can be effectively improved, and the specific capacity and the cycle life of the ternary positive electrode material can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of new energy materials, and particularly relates to a ternary cathode material, a preparation method thereof, and an electrochemical device. Background Art

[0002] In the field of lithium-ion battery cathode materials, single-crystalline materials have fewer grain boundaries inside the grains, and can effectively reduce internal stress during long-term cyclic charge and discharge processes, showing good structural stability. This characteristic helps to inhibit the capacity decay and structural stability damage of the material, making single-crystalline materials a key material for the field of lithium-ion battery materials with long cycle life.

[0003] However, the traditional preparation method of single-crystalline materials has a complex process, high energy consumption, and there is a phenomenon of soft agglomeration of the prepared single-crystalline particles, and the size and shape of the particles are difficult to precisely control. Summary of the Invention

[0004] In view of this, in order to solve at least one of the above technical problems, an embodiment of the present application provides a preparation method of a ternary cathode material.

[0005] An embodiment of the present application further provides a ternary cathode material prepared by the above preparation method of the ternary cathode material, and an electrochemical device using the ternary cathode material.

[0006] In a first aspect, an embodiment of the present application provides a ternary cathode material, the ternary cathode material is a single-crystalline ternary cathode material, the span of the particle size distribution of the ternary cathode material span = (D90 - D10) / D50, span is 0.8 to 1.1, and the average roundness R of the particles of the ternary cathode material is greater than or equal to 70%; Wherein, the average roundness R of the particles of the ternary cathode material is measured by the following test method: Obtain a scanning electron microscope image of the ternary cathode material, identify the two-dimensional projected area and outer diameter perimeter of the particles of the ternary cathode material in the scanning electron microscope image, the roundness e of a single particle = (4π × two-dimensional projected area) / (outer diameter perimeter × outer diameter perimeter), and the average roundness R of the ternary cathode material is the arithmetic mean of the roundness e of multiple single particles.

[0007] In some possible embodiments, the average roundness R of the particles of the ternary cathode material is 70% to 80%.

[0008] In some possible embodiments, the particle size D50 of the ternary cathode material is 3.0 μm to 4.0 μm; and / or The crystallinity of the ternary cathode material is greater than or equal to 98%.

[0009] In some possible embodiments, at a pressure of 200 MPa, the tap density of the ternary cathode material is 3.0 g / cm 3 ~3.6 g / cm 3 .

[0010] In some possible embodiments, the capacity retention rate of the ternary cathode material after cycling 4000 times at a rate of 1C within the voltage range of 2.8V - 4.4V at 45°C is > 80%.

[0011] In a second aspect, an embodiment of the present application provides a method for preparing the aforementioned ternary cathode material, including: mixing a first lithium source with a nickel-cobalt-manganese precursor to form a primary mixed material, and subjecting the primary mixed material to a primary sintering to obtain a primary sintered product, wherein the precursor is prepared by a continuous preparation method, and the molar ratio a of lithium element in the first lithium salt to transition metal elements in the nickel-cobalt-manganese precursor is 0.5 - 0.9; and mixing the primary sintered material with a second lithium source to form a secondary mixed material, and subjecting the secondary mixed material to a secondary sintering to obtain the ternary cathode material, wherein the molar ratio b of lithium element in the second lithium salt to transition metal elements in the nickel-cobalt-manganese precursor is 0.22 - 0.95, and 2 ≤ a / b ≤ 5, 1.0 ≤ a + b ≤ 1.1. The ternary cathode material is a single-crystal ternary cathode material. The particle size span distribution of the ternary cathode material span = (D90 - D10) / D50, span is 0.8 - 1.1, and the average circularity R of the particles of the ternary cathode material is greater than or equal to 70%; wherein, the average circularity R of the particles of the ternary cathode material is measured by the following test method: obtaining a scanning electron microscope image of the ternary cathode material, identifying the two-dimensional projected area and outer diameter perimeter of the particles of the ternary cathode material in the scanning electron microscope image, the circularity e of a single particle = (4π × two-dimensional projected area) / (outer diameter perimeter × outer diameter perimeter), and the average circularity R of the ternary cathode material is the arithmetic mean of the circularity e of multiple single particles.

[0012] In some possible embodiments, the span of the nickel-cobalt-manganese precursor is 0.9 - 1.3.

[0013] In some possible embodiments, the average particle size D50 of the nickel-cobalt-manganese precursor is 3.0 μm - 4.0 μm.

[0014] In some possible embodiments, the temperature of the primary sintering is 600°C - 800°C, and the time of the primary sintering is 5h - 10h; and / or the temperature of the secondary sintering is 700°C - 950°C, and the time of the secondary sintering is 5h - 10h.

[0015] In a third aspect, an embodiment of the present application provides an electrochemical device, the electrochemical device includes a positive electrode plate, the positive electrode plate includes a positive electrode active material, and the positive electrode active material is the aforementioned ternary positive electrode material.

[0016] Compared with the prior art, the ternary positive electrode material provided by the embodiment of the present application is a single-crystalline ternary positive electrode material. By controlling the span of the particle size distribution of the ternary positive electrode material to be 0.8 - 1.1, the span value close to 1 makes the particle size of the positive electrode material highly uniform, and the ternary positive electrode material has monodispersity. At the same time, by controlling the average circularity of the ternary positive electrode material to be greater than or equal to 70%, the higher circularity makes the particles of the ternary positive electrode material regular and round in shape, and it is not easy to occur particle soft agglomeration. By controlling the monodispersity and circularity of the single-crystalline ternary positive electrode material, the particle size distribution and shape of the ternary positive electrode material can be precisely controlled, thereby reducing the inter-particle porosity of the ternary positive electrode material, increasing the tap density. At the same time, it can effectively reduce the occurrence of particle soft agglomeration. In addition, the closely packed circular particles with uniform size can also reduce the poor conductivity in local areas, effectively improve the transmission rates of electrons and lithium ions, which is beneficial to improving the conductivity and cycle stability of the ternary positive electrode material and increasing the service life of the ternary positive electrode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a process flow chart of the preparation method of the ternary positive electrode material provided by an embodiment of the present application.

[0018] Figure 2 It is a scanning electron microscope image of the ternary positive electrode material in Example 1 of the present application.

[0019] Figure 3 It is a comparative scanning electron microscope image of the ternary positive electrode material in Comparative Examples 1 - 3 of the present application. Among them, Figure 3 Figure (a) in it is the SEM image of the ternary positive electrode material in Comparative Example 1, Figure 3 Figure (b) in it is the SEM image of the ternary positive electrode material in Comparative Example 2, Figure 3 Figure (c) in it is the SEM image of the ternary positive electrode material in Comparative Example 3.

[0020] Figure 4 It is a curve graph of the particle size number distribution of the ternary positive electrode material in Example 1 and Comparative Examples 1 - 3 of the present application.

[0021] Figure 5 It is a statistical graph of the particle circularity of the ternary positive electrode material in Example 1 and Comparative Examples 1 - 3. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] Embodiments of the present application will be described in detail below. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and should not be construed as limiting the present application. It should be noted that unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs; without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other; in the following description, many specific details are set forth in order to fully understand the present application, and the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments.

[0023] The embodiments of the present application provide a ternary cathode material, which is a single-crystal ternary cathode material. The particle size span distribution of the ternary cathode material span = (D90 - D10) / D50, span is 0.8 to 1.1, and the average circularity R of the particles of the ternary cathode material is greater than or equal to 70%; Among them, the average circularity R of the particles of the ternary cathode material is measured by the following test method: Obtain the scanning electron microscope image of the ternary cathode material, identify the two-dimensional projected area and the outer diameter perimeter of the particles of the ternary cathode material in the scanning electron microscope image. The circularity e of a single particle = (4π×two-dimensional projected area) / (outer diameter perimeter×outer diameter perimeter), and the average circularity R of the ternary cathode material is the arithmetic mean of the circularities e of multiple single particles.

[0024] Specifically, for the scanning electron microscope image obtained by scanning the ternary cathode material with a scanning electron microscope, combined with the metis vision software for identification, automatically identify the two-dimensional projected area of the particles and the outer diameter perimeter of the particles. The circularity e of a single particle = (4π×two-dimensional projected area) / (outer diameter perimeter×outer diameter perimeter), and the average circularity R of the particles of the ternary cathode material is the arithmetic mean of the circularities e of multiple single particles. It can be understood that the software includes not only metisvision, but also any software that can identify the two-dimensional projected area of the particles and the outer diameter perimeter of the particles.

[0025] Due to its highly ordered crystal structure and grain boundary-free characteristics, single-crystal ternary cathode materials exhibit high structural stability and good cycling performance. However, the existing single-crystal ternary cathode materials are prone to particle soft agglomeration during preparation and storage, which will hinder the uniform transmission of lithium ions, increase the interfacial impedance of the ternary cathode material, and also reduce the tap density of the ternary cathode material. These problems not only affect the electrochemical and physical properties of the ternary cathode material, but also limit the application range of the ternary cathode material.

[0026] To this end, in the embodiments of the present application, the particle size span distribution span of the ternary cathode material is controlled to be 0.8 to 1.1, span = (D90 - D10) / D50, where D10, D50, and D90 are statistical indicators of particle size based on number distribution, representing that 10%, 50%, and 90% of the particle sizes are less than or equal to this value, respectively, and are used to characterize the particle size distribution of the particle system. When the particle size span distribution span of the ternary cathode material is 0.8 to 1.1, the particle size span distribution is relatively narrow, and the size distribution of the ternary cathode material particles is relatively uniform. First, the monodisperse ternary cathode material has a close particle packing property, which can initially improve the tap density of the ternary cathode material, thereby improving the specific capacity of the ternary cathode material to a certain extent. Second, the uniform particle size distribution ensures the consistency of the lithium ion transmission path in the ternary cathode material, can reduce the interfacial impedance of the ternary cathode material, reduce the local polarization phenomenon, and thus improve the ion transmission rate of the ternary cathode material during charge and discharge. In addition, the above particle size span distribution can reduce the occurrence of too large or too small particles, and further reduce the structural instability caused by uneven particle size and the phenomena of scratches and tape breaks in the production of electrode sheets. By controlling the particle size distribution, from the perspective of improving the particle size uniformity of the ternary cathode material, the ternary cathode material can maintain relatively stable electrochemical performance during multiple charge and discharge cycles, thereby improving the cycle performance of the ternary cathode material and extending the service life of the ternary cathode material. Exemplarily, the span of the ternary cathode material can be 0.8, 0.85, 0.9, 0.95, 1.0, 1.05, 1.1 or any value within the range composed of any two of the above values. Further, the span of the ternary cathode material can be 0.95 to 1.05, and the span value close to 1 makes the particle size of the cathode material particles highly uniform, which can further improve the monodispersity of the ternary cathode material.

[0027] Meanwhile, by controlling the average circularity R of the ternary cathode material to be greater than or equal to 70%, it indicates that the particles of the ternary cathode material have a relatively regular shape and a high degree of roundness. The contact between particles with a higher circularity is more uniform and smooth, the porosity between particles decreases, and the round particles can nest and stack better with each other, reducing particle agglomeration and further improving the tap density of the ternary cathode material. The ternary cathode material with a higher circularity has better fluidity and can be more evenly distributed in the electrode during manufacturing, reducing the non-uniformity of the material during coating and pressing processes. This improvement in shape makes the battery manufacturing process more efficient, reduces the complexity of the process, and also improves the consistency and reliability during the production process. By controlling the circularity, from the perspective of improving the roundness of the particle morphology of the ternary cathode material, the ternary cathode material can maintain relatively stable electrochemical performance during multiple charge-discharge cycles, thereby improving the cycle performance of the ternary cathode material and extending the service life of the ternary cathode material. Exemplarily, the average circularity of the ternary cathode material can be 70%, 75%, 78%, 80%, 85%, 88%, 90%, 95%, 98%, 100% or any value within the range formed by any two of the above values. Further, the average circularity of the ternary cathode material can be 70% - 80%.

[0028] In this application, through the synchronous regulation of the particle size span distribution and average circularity of the ternary cathode material, the risk of particle soft agglomeration is effectively reduced, the tap density of the ternary cathode material is synergistically improved, the problem of poor conductivity in local areas is reduced, which is beneficial to improving the specific capacity and service life of the ternary cathode material. When the particle size span distribution is narrow (span is 0.8 - 1.1), but the average circularity is lower than 70%, it will cause poor particle morphology, resulting in a decrease in the fluidity and tap density of the ternary cathode material; when the average circularity of the ternary cathode material is greater than or equal to 70%, but the particle size span distribution is wide (span is not in the range of 0.8 - 1.1), although the particles have good roundness, the particle size difference is large, the interfacial impedance of the ternary cathode material increases, resulting in a decrease in the ion transport rate of the ternary cathode material.

[0029] In some embodiments, the D50 of the ternary cathode material can be 3.0 μm - 4.0 μm. The particle size in this range is relatively small, shortening the lithium ion transport path, which is beneficial to Li +The insertion and extraction enable the ternary cathode material to have good rate performance, and the smaller particle size can improve the mechanical properties of the ternary cathode material and reduce the risk of particle breakage. Generally, the smaller the particle size, the larger its specific surface area, the higher the surface energy of the particle, and the easier it is to generate particle agglomeration, which affects the conductivity. However, the ternary cathode material provided in this application has monodispersity and high roundness, which can balance the small particle size and high dispersibility of the ternary cathode material particles and effectively solve the problem of particle agglomeration caused by small particle size. Exemplarily, the particle size D50 of the ternary cathode material can be 3.0μm, 3.1μm, 3.2μm, 3.3μm, 3.4μm, 3.5μm, 3.6μm, 3.7μm, 3.8μm, 3.9μm, 4.0μm or any value within the range composed of any two of the above values.

[0030] In some embodiments, the crystallinity of the ternary cathode material can be greater than or equal to 98%. Through the highly ordered crystal structure, it is beneficial to reduce lattice defects, thereby further improving the structural stability of the ternary cathode material and enabling the ternary cathode material to better resist the generation of phase transformation and microcracks during cycling; at the same time, the highly crystallized single crystal structure can also provide a more unobstructed lithium ion transmission channel, further increasing the lithium ion diffusion rate and reducing the interfacial impedance, thereby improving the rate performance; in addition, the high crystallinity also enhances the thermal stability of the ternary cathode material, which is beneficial to improving the safety of the battery. The crystallinity of the ternary cathode material being greater than 98% means that the degree of single crystallization of the single crystal ternary cathode material is also relatively high, the crystal integrity of the particles is high, and at the same time, the number of single crystal-like aggregates in the particles decreases, and the number of fine powders generated by breakage during production and processing will correspondingly decrease, thus improving the electrochemical performance and mechanical strength of the ternary cathode material.

[0031] In some embodiments, the tap density of the ternary cathode material under a pressure of 200 Mpa can be 3.0 g / cm 3 ~3.6 g / cm 3 , and the ternary cathode material improves the tap density of the ternary cathode material together by improving the particle size, dispersibility, particle size distribution and roundness. When the tap density is within the foregoing range, it can effectively improve the energy density of the ternary cathode material, thereby increasing the capacity of the prepared battery. The tap density of the ternary cathode material under a pressure of 200 Mpa can further be 3.3 g / cm 3 ~3.6 g / cm 3 .

[0032] In some embodiments, the capacity retention rate of the ternary cathode material after cycling 4000 times at a rate of 1C within the voltage range of 2.8V - 4.4V at 45°C is > 80%, and the ternary cathode material has a long cycle life.

[0033] In some embodiments, the capacity retention rate of the ternary cathode material after 100 cycles at a rate of 1C within the voltage range of 2.8V to 4.4V at 45°C is > 93%, and the ternary cathode material exhibits good cycle stability at high temperatures and large charge-discharge rates.

[0034] It should be noted that the difference between the single-crystalline ternary cathode material and the polycrystalline ternary cathode material (i.e., polycrystalline secondary particles) is that the smallest particle of the polycrystalline secondary particle is a secondary particle formed by the aggregation of nanoscale primary particles. For the single-crystalline ternary cathode material, the smallest particle is usually a micron-scale monomer primary particle. It can be determined whether the obtained cathode product is a single-crystalline material through characterization means such as scanning electron microscopy (SEM). For example, for a single-crystalline cathode material, the morphology of the single-crystalline particles can be characterized by SEM, and it can be seen that the shape of the single-crystalline particles generally shows regular or irregular spherical shapes, and there is no significant particle aggregation. It should be further noted that the "single-crystalline ternary cathode material" well-known to those skilled in the art is not a "single crystal" in the strict crystallographic sense. Crystallographically, an ideal single crystal refers to a crystal with exactly the same arrangement and orientation. However, limited by impurities, strain, and crystal defects, ideal single crystals are very rare and difficult to produce in the laboratory. Therefore, the single-crystalline ternary cathode material well-known in the art is actually more of a "single-crystal-like morphology" cathode material, which only shows a large particle size similar to that of a single crystal in terms of size, different from the polycrystal composed of many small primary particles.

[0035] Compared with the prior art, the ternary cathode material provided by the embodiments of the present application has the following beneficial effects: 1. The single-crystalline ternary cathode material has good monodispersity and high roundness, indicating that the particle size distribution in the ternary cathode material is uniform, the shape is regular, the roundness is high, and there is less particle aggregation, which is beneficial to improving the tap density and ion transport rate of the ternary cathode material, thereby obtaining a ternary cathode material with long cycle life.

[0036] 2. Since the ternary cathode material provided by the present application can reduce particle aggregation, the particle size D50 of the ternary cathode material can be controlled within a small range (3.0μm to 4.0μm). The smaller particle size effectively shortens the lithium ion transport path, which is beneficial to the + insertion and extraction of Li, making the ternary cathode material have good rate performance.

[0037] Please refer to Figure 1 As shown, the embodiments of the present application provide a preparation method for the aforementioned ternary cathode material, which specifically includes the following steps: Step S1, mixing a first lithium salt with a nickel-cobalt-manganese precursor obtained by a continuous process to form a primary mixed material, and sintering the primary mixed material to obtain a primary sintered product, wherein a molar ratio a of the lithium element in the first lithium salt to the transition metal element in the nickel-cobalt-manganese precursor is 0.5-0.9.

[0038] Specifically, the first lithium salt and the nickel-cobalt-manganese precursor Ni prepared by the continuous process are x Co y Mn 1-x-y (OH)2 is mixed evenly with a Li / Me molar ratio a of 0.5 to 0.9 to obtain a primary mixed material, wherein 0.5≤x≤0.9, 0.05≤y≤0.25, 0.55≤x+y≤1, and Me is the sum of Ni, Co and Mn. The primary mixed material is then sintered once, and the first lithium salt is fully reacted with the nickel-cobalt-manganese precursor to obtain a primary sintered product, which has a single crystal phase.

[0039] In this step, the lithium source is added for the first time for sintering, and the ratio a of the molar amount of lithium element in the first lithium source and the total molar amount of transition metal elements in the nickel-cobalt-manganese precursor is controlled to be 0.5-0.9, which can effectively ensure the proper incorporation of lithium ions, so that lithium ions can be uniformly embedded in the lattice of the nickel-cobalt-manganese precursor, which is beneficial to promote single crystal growth, improve the crystallization degree and circularity of the crystal, and lithium incorporation into the crystalline phase is beneficial to improve the structural stability and cycle life of the ternary positive electrode material. Controlling the molar ratio a within the aforementioned range can reduce the excessive addition of the first lithium source (a is greater than 0.9), resulting in excessive residual lithium content in the first sintering product, affecting the rate performance of the ternary positive electrode material; and reduce the insufficient lithium incorporation caused by the addition of too little of the first lithium source (a is less than 0.5), resulting in reduced capacity and cycle performance of the ternary positive electrode material. a can be 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9 or any value within the range formed by any two of the above values. a can further be 0.65-0.85.

[0040] In some embodiments, the first lithium source may include at least one of lithium carbonate and lithium hydroxide.

[0041] In addition, the nickel-cobalt-manganese precursor is prepared by a continuous process rather than an intermittent process or a semi-continuous process, which can effectively improve the production efficiency of the nickel-cobalt-manganese precursor and reduce its manufacturing cost. The process of preparing the nickel-cobalt-manganese precursor by the continuous process mainly includes the following steps: First, a mixed solution is prepared by mixing a nickel source, a cobalt source, and a manganese source in a target ratio and continuously injecting it into a reactor through precise flow control; at the same time, a precipitant and a complexing agent are also continuously added to the reactor, and a coprecipitation reaction is carried out at a constant temperature and pH value to generate the nickel-cobalt-manganese precursor. During the reaction process, stirring and pH control are used to ensure uniform growth of the particles, forming spherical or quasi-spherical precursor particles. After the reaction is completed, the precursor slurry is filtered, washed, and dried to obtain the final precursor powder. This process has the characteristics of high efficiency, continuity, and strong controllability, and is suitable for large-scale production of high-performance cathode materials for lithium-ion batteries.

[0042] In some embodiments, the span of the particle size distribution of the nickel-cobalt-manganese precursor can be 0.9 to 1.3. The particle size distribution of the first sintered material can inherit that of the nickel-cobalt-manganese precursor, and to a certain extent, the ternary cathode material can also inherit the particle size distribution of the first sintered material. This particle size distribution range helps to control the span of the particle size distribution of the ternary cathode material within a narrow range.

[0043] In some embodiments, the average particle size D50 of the nickel-cobalt-manganese precursor can be 3.0 μm to 4.0 μm, which is beneficial for lithium ion insertion and for controlling the size of the particles of the first sintered product.

[0044] In some embodiments, the methods of mixing the first lithium source and the nickel-cobalt-manganese precursor can include mixing with a plowshare mixer, mixing with a high-speed mixer, stirring, or grinding, etc. It can be understood that the mixing methods include but are not limited to the above methods. Exemplarily, the first lithium salt and the nickel-cobalt-manganese precursor are mixed and stirred evenly by using a plowshare mixer, and the stirring time is 5 min to 50 min.

[0045] In some embodiments, the temperature of the first sintering can be 600 °C to 800 °C, and the time of the first sintering can be 5 h to 10 h. Such first sintering conditions are beneficial for the first lithium source and the nickel-cobalt-manganese precursor to fully undergo a chemical reaction, promote single crystal growth, and further improve the crystallization degree and roundness of the crystal. Exemplarily, the temperature of the first sintering can be 600 °C, 650 °C, 700 °C, 750 °C, 800 °C, or any value within the range composed of any two of the above values. Further, the temperature of the first sintering can be 500 °C to 750 °C. Exemplarily, the time of the first sintering can be 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, or any value within the range composed of any two of the above values. Further, the time of the first sintering can be 7 h to 10 h.

[0046] In some embodiments, the atmosphere for the first sintering can be an air atmosphere or an oxygen atmosphere, which is beneficial to reducing particle agglomeration, promoting uniform crystal growth, improving the spherical-like particle morphology of the crystal, and enhancing the crystal structure integrity and chemical composition stability of the first sintering product. The atmosphere for the first sintering can further be an oxygen atmosphere.

[0047] Step S2: Mix the first-sintered material and the second lithium source to form a secondary mixed material, and perform secondary sintering on the secondary mixed material to obtain a ternary cathode material. Among them, the molar ratio b of lithium element in the second lithium salt to transition metal elements in the nickel-cobalt-manganese precursor is 0.22 to 0.95, and 2 ≤ a / b ≤ 5, 1.0 ≤ a + b ≤ 1.1. The ternary cathode material is a single-crystal ternary cathode material. The particle size span distribution span = (D90 - D10) / D50 of the ternary cathode material is 0.8 to 1.1, and the average roundness R of the particles of the ternary cathode material is greater than or equal to 70%. Among them, the average roundness R of the particles of the ternary cathode material is measured by the following test method: Obtain a scanning electron microscope image of the ternary cathode material, identify the two-dimensional projected area and outer diameter perimeter of the particles of the ternary cathode material in the scanning electron microscope image. The roundness e of a single particle = (4π × two-dimensional projected area) / (outer diameter perimeter × outer diameter perimeter), and the average roundness R of the ternary cathode material is the arithmetic mean of the roundness e of multiple single particles.

[0048] Specifically, mix the second lithium salt with the first-sintered material evenly to obtain a secondary mixed material. Among them, the ratio b of the molar amount of lithium element in the second lithium salt to the total molar amount of transition metals in the nickel-cobalt-manganese precursor is 0.22 to 0.95. Then, perform secondary sintering and air-flow pulverization, secondary lithium supplementation and secondary sintering on the secondary mixed material. Utilize the fluxing effect of the lithium salt to promote the combination of the first-sintered material and the second lithium salt, and part of the second lithium salt melts during the sintering process to form a liquid phase, which is beneficial to the smoothing and rounding of the surface of the ternary cathode material particles, and secondarily repair the lithium loss and structural defects of the ternary cathode material, improving the crystallinity of the ternary cathode material. This step S2 further improves the particle size distribution, roundness and crystallinity of the ternary cathode material, and obtains a ternary cathode material with a high degree of single crystallization, good roundness, and monodispersity.

[0049] In this step, the lithium source is added for the second time for secondary sintering, and the molar ratio b is controlled to be 0.22~0.95, which can accurately control the amount and distribution of lithium elements, ensure the full reaction of metal elements such as nickel, cobalt and manganese with lithium, and further improve the structural stability and cycle life of the ternary positive electrode material. Controlling the molar ratio b within the aforementioned range can reduce the excessive residual lithium content of the ternary positive electrode material caused by excessive addition of the second lithium source (b is greater than 0.95), and the deposition or precipitation of lithium during charging and discharging, causing the structural stability of the ternary positive electrode material to decrease and the capacity to decay; and reduce the energy density and capacity of the ternary positive electrode material caused by too little addition of the second lithium source (b is less than 0.22), thereby meeting the needs of high energy density batteries. b can be 0.22, 0.25, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95 or any value within the range composed of any two of the above values. b can further be 0.25~0.60.

[0050] Moreover, a and b must also satisfy: 2≤a / b≤5. Controlling the ratio of the first lithium source addition and the second lithium source addition is conducive to using the appropriate amount of the second lithium salt added b (i.e., the amount of secondary lithium supplementation) to enhance the second lithium salt's modification effect on the circularity of the ternary positive electrode material particles. When a / b is too low (a / b<2), b is too much compared to a, resulting in excessive residual lithium or lithium precipitation, resulting in poor particle morphology of the ternary positive electrode material, and the circularity of the ternary positive electrode material is low; when a / b is too high (a / b>5), b is insufficient compared to a, and the morphology of the ternary positive electrode material cannot be fully repaired, and the circularity of the ternary positive electrode material will also be low. In addition, the amount of the first lithium salt added a (i.e., the amount of primary lithium supplementation) is 2 to 5 times that of b, which is also conducive to controlling the lower limit of lithium addition, ensuring the lithium content of the ternary positive electrode material, reducing the temperature of the primary sintering reaction, and reducing energy consumption costs.

[0051] In addition, a and b also satisfy: 1.0≤a+b≤1.1. Controlling the ratio of the total molar amount of lithium in the first lithium salt and the second lithium salt to the total molar amount of transition metal in the nickel-cobalt-manganese precursor within the range of 1 to 1.1 is beneficial to avoid the excessive total amount of lithium source added twice (a+b>1.1), which leads to the enrichment of residual lithium on the surface of the ternary positive electrode material, thereby reducing the first efficiency; it is also beneficial to avoid the total amount of lithium source added twice being too little (a+b<1). Too little lithium content will form lithium vacancies, resulting in lattice distortion of the ternary positive electrode material, reducing cycle stability, and causing capacity decay of the ternary positive electrode material. In some embodiments, the second lithium source may include at least one of lithium carbonate and lithium hydroxide.

[0052] In some embodiments, the method of mixing the second lithium source and the primary sintered product may include mixing with a plowshare mixer, mixing with a high-speed mixer, stirring, or grinding, etc. It can be understood that the mixing methods include but are not limited to the above methods. Exemplarily, a plowshare mixer is used to mix and stir the second lithium source and the primary sintered product evenly, and the stirring time is 5 min to 50 min.

[0053] In some embodiments, the temperature of the secondary sintering may be 700 °C to 950 °C, and the time of the secondary sintering may be 5 h to 10 h. The second lithium source reacts fully with the primary sintered product, which is beneficial to refining the particles of the ternary cathode material, controlling the size of the particles of the ternary cathode material, and making the particles of the ternary cathode material have higher roundness and a narrower particle size distribution. Exemplarily, the temperature of the secondary sintering may be 700 °C, 750 °C, 800 °C, 850 °C, 900 °C, 950 °C, or any value within the range composed of any two of the above values. Further, the temperature of the secondary sintering may be 850 °C to 950 °C. Exemplarily, the time of the secondary sintering may be 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, or any value within the range composed of any two of the above values. Further, the time of the secondary sintering may be 7 h to 10 h.

[0054] In some embodiments, the atmosphere of the secondary sintering may be an air atmosphere or an oxygen atmosphere, which is beneficial to improving the particle morphology and size of the ternary cathode material, thereby improving the conductivity and energy density of the ternary cathode material. Further, the atmosphere of the primary sintering may be an oxygen atmosphere.

[0055] The embodiments of the present application adopt the method of adding lithium sources step by step (adding the first lithium source and the second lithium source step by step) and step-by-step sintering (performing primary sintering and secondary sintering step by step), and realize more uniform particle growth and morphology control by optimizing the reaction and sintering processes. Adding lithium salts step by step can avoid excessive local concentration caused by adding too much lithium salt at one time, make the lithium salt and the nickel-cobalt-manganese precursor mix more evenly, slow down the reaction rate, thereby reducing particle agglomeration and improving the uniformity of chemical reactions; at the same time, the step-by-step sintering method controls the grain growth rate through two sinterings, avoids excessive growth or sintering agglomeration of particles at high temperatures, and maintains the monodispersity and round and regular morphology of the particles. The two work together to reduce the soft agglomeration of the particles of the ternary cathode material, improve the particle size screening property and particle roundness of the ternary cathode material, thereby obtaining a ternary cathode material with high single crystal particle roundness and uniform particle distribution. At the same time, the production efficiency of the preparation process can be improved, and the energy consumption can be reduced. Due to the good monodispersity and roundness of the ternary cathode material, the porosity between particles is reduced, so that the ternary cathode material has higher tap density, rate performance, cycle performance and capacity.

[0056] Compared with the prior art, the preparation method of the ternary cathode material provided by the embodiments of the present application has the following beneficial effects: 1. The continuous process is adopted to prepare the nickel-cobalt-manganese precursor. Compared with the batch process or semi-continuous process, it can effectively improve the production efficiency of the nickel-cobalt-manganese precursor and reduce the manufacturing cost of the nickel-cobalt-manganese precursor, thereby improving the production efficiency of the ternary cathode material and reducing the manufacturing cost of the ternary cathode material.

[0057] 2. By adopting the method of stepwise adding lithium source and stepwise sintering, the nickel-cobalt-manganese precursor prepared by the continuous process can be efficiently processed, reducing the soft agglomeration of the ternary cathode material particles, improving the crystallinity, monodispersity and roundness of the single-crystal ternary cathode material, while improving the production efficiency and reducing the energy consumption.

[0058] 3. Combining the stepwise addition of lithium source and stepwise sintering with the continuous process to prepare the ternary cathode material, this preparation method has simple, efficient process, can effectively reduce energy consumption and cost, is conducive to the large-scale production of the ternary cathode material, and has excellent commercial prospects.

[0059] The embodiment of the present application also provides an electrochemical device (such as a battery), which includes a positive electrode sheet. Among them, the positive electrode sheet includes a positive electrode active material, and the positive electrode active material is the ternary cathode material as described above.

[0060] The electrochemical device prepared by using the aforementioned ternary cathode material has the advantages of high capacity, high cycle performance and low cost, which is conducive to the large-scale application of the ternary cathode material.

[0061] The aforementioned ternary cathode material, its preparation method and electrochemical device are further described below through specific examples.

[0062] Example 1 Step S1: Put the first lithium source lithium carbonate and 300 kg of the continuous Ni 0.7 Co 0.1 Mn 0.2 (OH)2 nickel-cobalt-manganese precursor prepared by the continuous process into a plowshare mixer and mix for 30 minutes to form a primary mixed material. Among them, the molar ratio a of lithium element in lithium carbonate to transition metal elements in the nickel-cobalt-manganese precursor is 0.8, the span of the nickel-cobalt-manganese precursor is 1.1, and the D50 is 3.6 μm. Put the primary mixed material into a muffle furnace and sinter it for the first time under an oxygen atmosphere to obtain a first sintered product. The temperature of the first sintering is 700 °C, and the time of the first sintering is 6 h.

[0063] Step S2: Put the above-mentioned primary sintered material and the second lithium source lithium carbonate into a plowshare mixer and mix for 30 minutes to form a secondary mixed material. Among them, in this step, the molar ratio b of lithium element in the input lithium carbonate to the transition metal element in the nickel cobalt manganese precursor is 0.25. Then, perform secondary sintering and airflow pulverizer dispersion and crushing on the secondary mixed material in an oxygen atmosphere in a muffle furnace to obtain a ternary cathode material with a D50 of 3.0 μm to 4.0 μm. The temperature of the secondary sintering is 900 °C, and the time of the secondary sintering is 6 hours.

[0064] Example 2 The difference from Example 1 is that: in Step S1, the span of the nickel cobalt manganese precursor is 0.9. Other steps are basically the same as those in Example 1, please refer to Example 1.

[0065] Example 3 The difference from Example 1 is that: in Step S1, the molar ratio a of lithium element in the first lithium source lithium carbonate to the transition metal element in the nickel cobalt manganese precursor is 0.85; in Step S2, the molar ratio b of lithium element in the added second lithium source lithium carbonate to the transition metal element in the nickel cobalt manganese precursor is 0.2. Other steps are basically the same as those in Example 1, please refer to Example 1.

[0066] Example 4 The difference from Example 1 is that: in Step S1, the molar ratio a of lithium element in the added first lithium source lithium carbonate to the transition metal element in the nickel cobalt manganese precursor is 0.75; in Step S2, the molar ratio b of lithium element in the added first lithium source lithium carbonate to the transition metal element in the nickel cobalt manganese precursor is 0.34. Other steps are basically the same as those in Example 1, please refer to Example 1.

[0067] Comparative Example 1 The difference from Example 1 is that: in Step S1, the nickel cobalt manganese precursor is an intermittently distributed Ni 0.7 Co 0.1 Mn 0.2 (OH)2 nickel cobalt manganese precursor, and the span of the nickel cobalt manganese precursor is 0.6. Other steps are basically the same as those in Example 1, please refer to Example 1.

[0068] Comparative Example 2 Mix lithium carbonate with 300 kg of intermittently distributed Ni 0.7 Co 0.1 Mn 0.2The nickel cobalt manganese precursor of (OH)2 is put into a plowshare mixer and mixed for 30 minutes to form a mixed material. Among them, the molar ratio of lithium element in lithium carbonate to transition metal elements in the nickel cobalt manganese precursor is 1.05, the span of the nickel cobalt manganese precursor is 0.6, and the D50 is 3.6 μm. The mixed material is put into a muffle furnace and sintered in an oxygen atmosphere to obtain a ternary cathode material. The sintering temperature is 900 °C and the sintering time is 12 h.

[0069] Comparative Example 3 The difference from Example 1 is that: in step S2, the secondary sintering temperature is 900 °C and the secondary sintering time is 12 h. Other steps are basically the same as those in Example 1, please refer to Example 1.

[0070] The ternary cathode materials obtained in Examples 1-4 and Comparative Examples 1-3 are tested as follows.

[0071] Testing methods: 1. Scanning electron microscopy (SEM) test. A JSM-IT210 model scanning electron microscope is used. This model instrument has high-resolution imaging ability and can clearly observe the microscopic morphology and structural characteristics of the cathode material. The acceleration voltage is 10.00 kV and the magnification is 10,000 times.

[0072] 2. Crystallinity determination: An X-ray diffractometer is used for XRD microscopic structure characterization, and the crystallinity data of the 110 crystal plane is calculated and generated using jade software.

[0073] 3. Particle size determination: Mastersizer 3000 laser diffraction technology is used to measure the particle size. After ultrasonic dispersion for 5 minutes, the particle size distribution is tested. When the laser beam passes through the dispersed particle sample, the particle size measurement is completed by measuring the intensity of the scattered light. Then the data is used to analyze and calculate the particle size distribution of the particles forming the scattered spectrogram. D50: is the median particle size, which is the particle size corresponding to when the cumulative particle size distribution percentage of a sample reaches 50%. D90, D50, and D10 are the particle sizes corresponding to when the cumulative distribution in the distribution curve is 90%, 50%, and 10% respectively. span = (D90 - D10) / D50.

[0074] 4. Circularity: The SEM and software recognition combination method is used. The software is metis vision to automatically identify the two-dimensional projected area and the outer diameter perimeter of all photographed particles under a 1000-fold scanning electron microscope. The circularity calculation formula is e = (4π × two-dimensional projected area) / (outer diameter perimeter × outer diameter perimeter), and the average circularity R of the particles is the arithmetic mean of the circularity e of multiple single particles.

[0075] 5. Compaction density measurement: The powder density after pressing at 200 MPa was tested according to the method specified in the standard drafted by the National Nonferrous Metals Standardization Technical Committee, "Determination of Compaction Density of Lithium-Ion Battery Cathode Material Powder".

[0076] 6. Electrochemical performance test: The electrical performance was tested using a coin cell. After weighing the above cathode material, polyvinylidene fluoride (PVDF), and conductive agent (such as acetylene black or conductive carbon black) according to a mass ratio of 90:5:5, a half-cell was made. A LAND battery test system was used for constant current charge and discharge tests.

[0077] (I) Rate performance test: The test working voltage range was 2.8 V to 4.4 V, the temperature was 25 °C, the charge and discharge rate was +1C / -1C, the CV cut-off current was 0.01C, and the first discharge specific capacity and first efficiency of the ternary cathode material were tested.

[0078] (II) Cycle performance test: When the test working voltage range was 2.8 V to 4.4 V, the temperature was 45 °C, the charge and discharge rate was +1C / -1C, and the CV cut-off current was 0.01C, the capacity retention rate after 100 cycles was tested.

[0079] When the test working voltage range was 2.8 V to 4.4 V, the temperature was 45 °C, the charge and discharge rate was +1C / -1C, and the CV cut-off current was 0.01C, the capacity retention rate after 4000 cycles was tested.

[0080] The relevant test results of Examples 1-4 and Comparative Examples 1-3 are shown in Table 1.

[0081] The above results show: As Figure 2 shown, it is the SEM image of the ternary cathode material of Example 1. It can be seen from Figure 2 that Example 1 can form single crystal particles with good dispersion, uniform particle size distribution, and high roundness. As Figure 3 shown, it is the SEM image of the ternary cathode material of Comparative Examples 1-3. Figure 3 Figure (a) in Figure 3 is the SEM image of the ternary cathode material of Comparative Example 1. Figure 3 Figure (b) in Figure 3It can be seen that there are particles with irregular shapes in Comparative Examples 1-3, and there are obvious differences in particle sizes. Among them, in Comparative Example 2, there are more irregularly shaped particles in the single crystal particles obtained by direct single-step lithium addition and single-step sintering, and there are some soft agglomerated particles that are difficult to break up. This indicates that the dispersibility of the single crystal ternary cathode material obtained by the method of stepwise lithium addition and stepwise sintering in Example 1 is significantly better than that of the direct firing method in Comparative Example 2, and particle agglomeration is reduced.

[0082] Further combined with Figure 4 shown, are the particle size number distribution curves of the ternary cathode materials of Example 1 and Comparative Examples 1-3. From Figure 4 it can be seen that the particle size number distribution curve of the ternary cathode material of Example 1 has no bimodal distribution peak shape and is relatively narrow, while the particle size distributions in Comparative Examples 2 and 3 are significantly more dispersed, showing a bimodal distribution, and the proportion of small particle numbers is relatively high, which is likely to cause a rapid deterioration of the long-term cycling performance in the later stage.

[0083] Figure 5 is the statistical chart of the particle roundness of the ternary cathode materials of Example 1 and Comparative Examples 1-3. The particle roundness of the ternary cathode material in Example 1 reaches more than 72%, which is higher than that of Comparative Examples 1-3. Among them, in Comparative Example 2, an intermittent process was used to prepare the nickel-cobalt-manganese precursor, and a single-step lithium addition and single-step sintering method was used. The average particle roundness of the prepared ternary cathode material is only 65.4%.

[0084] Combined with Figures 2 to 5 , analyzing Table 1 above: Compared with Comparative Examples 1-3, Examples 1-4 of the present application adopt the stepwise lithium addition and stepwise sintering process, and control the amount of stepwise lithium addition, so that the prepared ternary cathode material has both monodispersity and high roundness. The dispersibility is between 0.9 and 1.1, and the average roundness is greater than 70%. The tap density of the ternary cathode material is improved, and the tap density is greater than 3.42 g / cm 3 , thereby improving the capacity and cycling performance of the battery. Under the discharge condition of 0.1C rate in the voltage range of 2.8V to 4.4V, the initial discharge specific capacity of the material reaches 203.8 mAh / g or more, and the initial efficiency reaches 90.46% or more. The capacity retention rate after 100 cycles at 1C rate in the voltage range of 2.8V to 4.4V at 45°C > 93.88%.

[0085] Comparing Example 1 and Comparative Example 1, in Comparative Example 1, the precursor prepared by the continuous preparation method was replaced with the precursor prepared by the batch preparation method. Although from the particle size distribution of the final ternary cathode material, the monodispersity of the particles of the ternary cathode material in Comparative Example 1 is basically equivalent to that in Example 1. However, considering the comparison of the production cost and production capacity of the batch precursor, compared with the continuous wide-distribution precursor used in Example 1, Comparative Example 1 is at an obvious disadvantage: under the production capacity condition of 6T / day output per single reactor, compared with the production capacity of the continuous nickel-cobalt-manganese precursor, the preparation of the batch nickel-cobalt-manganese precursor has a statistical excess of incompletely grown small particles accounting for about 6% during the period of opening the reactor and terminating the reaction. Due to this production capacity disadvantage and increased unit price cost, and the final cycle capacity retention rate of the ternary cathode material shows no improvement compared with the continuous precursors in Examples 1-4. Considering from the perspective of manufacturing cost, the manufacturability of Comparative Example 1 is insufficient.

[0086] Comparing Example 1 and Comparative Example 2, the shape of the ternary cathode material obtained in Comparative Example 2 is irregular, with low roundness, and there is particle agglomeration, resulting in a decrease in the tap density of the ternary cathode material. This is because in Comparative Example 2, a batch nickel-cobalt-manganese precursor was used for one-step lithium doping and sintering, and the average circularity of the particles decreased significantly, only 65.4%. In addition, Example 1 uses a continuous process to prepare the nickel-cobalt-manganese precursor, which can effectively improve the production efficiency of the nickel-cobalt-manganese precursor and reduce the manufacturing cost of the nickel-cobalt-manganese precursor. However, Comparative Example 2 uses a batch process to prepare the nickel-cobalt-manganese precursor. Referring to Comparative Example 1, the production cost of Comparative Example 2 is relatively high and the production capacity is low.

[0087] Comparing Example 1 and Comparative Example 3, the secondary sintering time used in Comparative Example 3 was 12h, the sintering time was too long, and over-sintering occurred. The circularity of the obtained ternary cathode material was only 68.1%, lower than 70%, and the particles were abnormally large, resulting in a significant attenuation of the cycle performance of the ternary cathode material.

[0088] It can be seen from this that in Examples 1-4 of the present application, by using a continuous process to prepare the nickel-cobalt-manganese precursor, compared with the batch process or semi-continuous process, and combined with the method of stepwise adding the lithium source and stepwise sintering, the nickel-cobalt-manganese precursor can be efficiently processed, the soft agglomeration of the ternary cathode material particles can be reduced, the monodispersity and roundness of the single-crystal ternary cathode material can be improved, and at the same time, the production efficiency can be increased and the energy consumption can be reduced.

[0089] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present invention. However, the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims

1. A ternary positive electrode material, characterized in that: The ternary positive electrode material is a single crystal ternary positive electrode material, the particle size span distribution of the ternary positive electrode material is span=(D90-D10) / D50, the span is 0.8-1.1, and the average circularity R of the particles of the ternary positive electrode material is greater than or equal to 70%; The average circularity R of the particles of the ternary positive electrode material is measured by the following test method: Obtain a scanning electron microscope image of the ternary positive electrode material, identify the two-dimensional projection area and outer diameter circumference of the particles of the ternary positive electrode material in the scanning electron microscope image, the circularity e of a single particle = (4π×two-dimensional projection area) / (outer diameter circumference×outer diameter circumference), and the average circularity R of the ternary positive electrode material is the arithmetic mean of the circularities e of multiple single particles.

2. The ternary positive electrode material according to claim 1, characterized in that: The average circularity R of the particles of the ternary positive electrode material is 70% to 80%.

3. The ternary cathode material according to claim 1, characterized in that: The particle size D50 of the ternary positive electrode material is 3.0 μm to 4.0 μm; and / or The crystallinity of the ternary positive electrode material is greater than or equal to 98%.

4. The ternary cathode material according to claim 1, characterized in that: At a pressure of 200 MPa, the compaction density of the ternary cathode material is 3.0 g / cm 3 ~3.5g / cm 3 .

5. The ternary cathode material according to claim 1, characterized in that: The capacity retention rate of the ternary positive electrode material after cycling for 4000 cycles at 1C rate within a voltage range of 2.8V to 4.4V at 45°C is greater than 80%.

6. A method for preparing a ternary positive electrode material, characterized in that: include: Mixing a first lithium source with a nickel-cobalt-manganese precursor to form a primary mixed material, and performing a primary sintering on the primary mixed material to obtain a primary sintered product, wherein the precursor is prepared by a continuous preparation method, and a molar ratio a of lithium element in the first lithium salt to transition metal element in the nickel-cobalt-manganese precursor is 0.5-0.9; and The primary sintered material and the second lithium source are mixed to form a secondary mixed material, and the secondary mixed material is subjected to secondary sintering to obtain the ternary positive electrode material, wherein the molar ratio b of the lithium element in the second lithium salt to the transition metal element in the nickel-cobalt-manganese precursor is 0.22-0.95, and 2≤a / b≤5, 1.0≤a+b≤1.1, the ternary positive electrode material is a single crystal ternary positive electrode material, the particle size span distribution of the ternary positive electrode material is span=(D90-D10) / D50, span is 0.8-1.1, and the average circularity R of the particles of the ternary positive electrode material is greater than or equal to 70%; The average circularity R of the particles of the ternary positive electrode material is measured by the following test method: Obtain a scanning electron microscope image of the ternary positive electrode material, identify the two-dimensional projection area and outer diameter circumference of the particles of the ternary positive electrode material in the scanning electron microscope image, the circularity e of a single particle = (4π×two-dimensional projection area) / (outer diameter circumference×outer diameter circumference), and the average circularity R of the ternary positive electrode material is the arithmetic mean of the circularities e of multiple single particles.

7. The method for preparing a ternary cathode material according to claim 6, characterized in that: The span of the nickel-cobalt-manganese precursor is 0.9-1.

3.

8. The method for preparing the ternary cathode material according to claim 6, characterized in that: The average particle size D50 of the nickel-cobalt-manganese precursor is 3.0 μm to 4.0 μm.

9. The method for preparing a ternary cathode material according to claim 6, characterized in that: The primary sintering temperature is 600° C. to 800° C., and the primary sintering time is 5 h to 10 h; and / or The temperature of the secondary sintering is 700° C. to 950° C., and the time of the secondary sintering is 5 h to 10 h.

10. An electrochemical device, characterized in that: The electrochemical device comprises a positive electrode plate, wherein the positive electrode plate comprises a positive electrode active material, and the positive electrode active material is a ternary positive electrode material as described in any one of claims 1 to 5 or a ternary positive electrode material prepared by the preparation method of a ternary positive electrode material as described in any one of claims 6 to 9.

Images