Single-crystal ternary positive electrode material, preparation process and application thereof

Abstract

The application discloses a single-crystal ternary positive electrode material and a preparation process and application thereof. x Ni y Co z M a O b , wherein M is at least one of Mn and Al; 0.8<=x<1.2, 0.6<=y<=0.95, 0<=z<=0.2, 0<=a<=0.2; and the lithium-nickel mixed arrangement degree s of the positive electrode material is less than 4%. The single-crystal ternary positive electrode material is applied to a lithium ion battery positive electrode, and is favorable for improving the first coulomb efficiency and the charge-discharge capacity of the battery, and can effectively improve the performance of the battery.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion batteries, specifically to a single-crystal ternary cathode material, its preparation process, and its applications. Background Technology

[0002] With societal development and the increasing depletion of fossil fuels, the development of new energy sources has received growing attention, and rechargeable batteries are considered one of the most promising energy storage devices. Among numerous chemical power sources, lithium-ion batteries have garnered widespread attention due to their high energy density and long lifespan. As the cathode material for lithium-ion batteries, high-nickel ternary cathode materials with high specific capacity have become a focus of attention. These layered ternary cathode materials consist of alternating layers of lithium atoms and transition metal atoms. However, because the radii of divalent nickel ions are close to those of lithium ions, lithium-nickel mixing easily occurs during material synthesis and electrochemical reactions, leading to reduced structural stability, initial coulombic efficiency, and charge / discharge capacity.

[0003] Traditional polycrystalline high-nickel ternary cathode materials suffer from numerous grain boundaries due to the secondary spheres being composed of a large number of smaller primary particles. This leads to side reactions with the electrolyte during electrochemical reactions and secondary sphere cracking during long-term cycling, resulting in rapid performance degradation. Therefore, monocrystalline high-nickel ternary cathode materials have become a popular research area. Monocrystalline materials possess larger primary particles and smoother surfaces, exhibiting significantly better structural stability and long-term cycling stability than polycrystalline materials. CN112133904A discloses a high-nickel ternary cathode material for lithium-ion batteries and its preparation method. The preparation method includes the following steps: uniformly mixing a ternary precursor with lithium hydroxide, performing a first sintering in an atmosphere furnace, mixing the resulting product with water, adding a corrosion inhibitor, washing, mixing the resulting product with an oxide, and then performing a second sintering in an atmosphere furnace to obtain the cathode material. For monocrystalline materials, the higher calcination temperature compared to polycrystalline materials leads to severe lithium-nickel mixing, which is detrimental to the material's charge / discharge capacity and initial coulombic efficiency. Summary of the Invention

[0004] To address the problems of high lithium-nickel mixing ratio, low charge-discharge capacity, and low initial coulombic efficiency in existing single-crystal ternary cathode materials, this invention provides a single-crystal ternary cathode material, its preparation process, and its applications. When applied to lithium-ion batteries, this single-crystal ternary cathode material can significantly improve discharge specific capacity and initial coulombic efficiency.

[0005] The first aspect of this invention provides a single-crystal ternary cathode material with the chemical formula Li. x Ni y Co z Ma O b , where M is at least one of Mn and Al; 0.8 ≤ x < 1.2, 0.6 ≤ y ≤ 0.95, 0 < z ≤ 0.2, 0 < a ≤ 0.2, and according to the valence state and content change of different elements, the proportion of oxygen element conforms to the principle of electrical neutrality; in the positive electrode material, the lithium-nickel mixing degree s is less than 4%, preferably less than 2%.

[0006] Furthermore, in the single-crystal ternary positive electrode material, the lithium-nickel mixing degree s satisfies: 0 < s < 4%, preferably 0 < s < 2%.

[0007] Furthermore, in the single-crystal ternary positive electrode material, 0.9 ≤ x < 1.1, 0.8 ≤ y ≤ 0.95, 0 < z ≤ 0.15, 0 < a ≤ 0.15; preferably, 0.9 ≤ x < 1.1, 0.8 ≤ y ≤ 0.95, 0 < z ≤ 0.05, 0 < a ≤ 0.15.

[0008] Furthermore, in the single-crystal ternary positive electrode material, the size of the primary particles is 2.0 - 5.0 μm, preferably 3.0 - 5.0 μm.

[0009] Furthermore, in the XRD pattern of the single-crystal ternary positive electrode material, the diffraction peak intensities I(003) and I(104) of the crystal plane (003) and the crystal plane (104) satisfy the following relationship: I(003) / I(104) is greater than 1.800, preferably greater than 1.900, and further preferably greater than 2.000.

[0010] Furthermore, in the XRD pattern of the single-crystal ternary positive electrode material, the diffraction peak intensities I(003) and I(104) of the crystal plane (003) and the crystal plane (104) satisfy the following relationship: 1.800 < I(003) / I(104) < 2.500, preferably 2.000 < I(003) / I(104) < 2.400.

[0011] Furthermore, in the single-crystal ternary positive electrode material, the c / a ratio in the lattice parameters is greater than 4.9350, preferably greater than 4.9365, and further preferably greater than 4.9380.

[0012] Furthermore, in the single-crystal ternary positive electrode material, the c / a ratio in the lattice parameters satisfies: 4.9350 < c / a < 4.9500, preferably 4.9380 < c / a < 4.9500.

[0013] The second aspect of the present invention provides a preparation process for a single-crystal ternary positive electrode material, including the following steps:

[0014] Mix the ternary positive electrode material precursor with a lithium source, calcine, and crush to obtain the single-crystal ternary positive electrode material.

[0015] Furthermore, the calcination adopts a three-stage temperature-controlled calcination process, wherein the temperature T1 of the first stage of calcination is 400-600℃ and the calcination time t1 is 4-7 hours; the temperature T2 of the second stage of calcination is 800-1100℃ and the calcination time t2 is 0.1-6 hours; and the temperature T3 of the third stage of calcination is 600-900℃ and the calcination time t3 is 6-18 hours.

[0016] Furthermore, during the first stage of calcination, the temperature is increased from room temperature (25-30℃) to T1 at a rate of 2-8℃ / min. Preferably, the temperature T1 of the first stage of calcination is 450-550℃, and the time t1 is 5-7 hours.

[0017] Furthermore, during the second-stage calcination process, the temperature is increased from T1 to T2 at a rate of 2-10℃ / min. Preferably, the temperature T2 of the second-stage calcination is 850-1000℃, and the time t2 is 0.5-4 hours.

[0018] Furthermore, during the third-stage calcination process, the temperature is reduced from T2 to T3 at a cooling rate of 2-10℃ / min. Preferably, the temperature T3 of the third-stage calcination is 700-800℃, and the time t3 is 9-15 hours.

[0019] Furthermore, in the three-stage temperature-controlled calcination process, t2 is less than t1 and t3, and T2 is greater than T1 and T3. Preferably, the calcination temperature and time follow the rule t3>t1>t2, and T2>T3>T1.

[0020] Furthermore, the lithium source is one or more of anhydrous lithium hydroxide, lithium hydroxide monohydrate, lithium carbonate, lithium phosphate, and lithium oxalate, preferably one or more of anhydrous lithium hydroxide and lithium hydroxide monohydrate.

[0021] Furthermore, the ternary cathode material precursor is a hydroxide precursor containing nickel-cobalt-manganese, nickel-cobalt-aluminum, or nickel-cobalt-manganese-aluminum, with the chemical formula Ni. y Co z M a (OH)2, wherein M is at least one of Mn and Al; 0.6≤y≤0.95, 0<z≤0.2, 0<a≤0.2, and y+z+a=1; preferably, 0.8≤y≤0.95, 0<z≤0.15, 0<a≤0.15, and y+z+a=1; more preferably, 0.8≤y≤0.95, 0<z≤0.05, 0<a≤0.15, and y+z+a=1.

[0022] Further, the molar ratio of the lithium source to the ternary cathode material precursor in the mixture is 1:1 to 1.3:1, preferably 1.05:1 to 1.2:1.

[0023] Further, during the three-stage program calcination process, the calcination atmosphere is one of nitrogen, air or high-purity oxygen.

[0024] Further, the mixing is carried out by a conventional physical mixing method, such as grinding, so that the ternary cathode material precursor and the lithium source are in full contact.

[0025] Further, the crushing method is a method such as air jet crushing or ball milling crushing, and the crushing time is 2 to 10 hours.

[0026] Further, the chemical formula of the single crystal ternary cathode material is Li x Ni y Co z M a O b , where M is at least one of Mn and Al; 0.8 ≤ x < 1.2, 0.6 ≤ y ≤ 0.95, 0 < z ≤ 0.2, 0 < a ≤ 0.2. According to the valence state and content changes of different elements, the proportion of oxygen element conforms to the principle of electrical neutrality.

[0027] Further, in the single crystal ternary cathode material, 0.9 ≤ x < 1.1, 0.8 ≤ y ≤ 0.95, 0 < z ≤ 0.15, 0 < a ≤ 0.15; preferably, 0.9 ≤ x < 1.1, 0.8 ≤ y ≤ 0.95, 0 < z ≤ 0.05, 0 < a ≤ 0.15.

[0028] Further, in the single crystal ternary cathode material, the lithium-nickel mixing degree s is less than 4%, preferably less than 2%. Preferably, the lithium-nickel mixing degree s satisfies: 0 < s < 4%, preferably 0 < s < 2%.

[0029] Further, in the single crystal ternary cathode material, the size of the primary particles is 2.0 - 5.0 μm, preferably 3.0 - 5.0 μm.

[0030] Further, in the XRD pattern of the single crystal ternary cathode material, the diffraction peak intensities I(003) and I(104) of the crystal plane (003) and the crystal plane (104) satisfy the following relationship: I(003) / I(104) is greater than 1.800, preferably greater than 1.900, and further preferably greater than 2.000.

[0031] Further, in the XRD pattern of the single-crystalline ternary cathode material, the diffraction peak intensities I(003) and I(104) of the crystal plane (003) and the crystal plane (104) satisfy the following relationship: 1.800 < I(003) / I(104) < 2.500, preferably 2.000 < I(003) / I(104) < 2.400.

[0032] Further, in the single-crystalline ternary cathode material, the c / a ratio in the lattice parameters is greater than 4.9350, preferably greater than 4.9365, and more preferably greater than 4.9380.

[0033] Further, in the single-crystalline ternary cathode material, the c / a ratio in the lattice parameters satisfies: 4.9350 < c / a < 4.9500, preferably 4.9380 < c / a < 4.9500.

[0034] The third aspect of the present invention provides the application of the single-crystalline ternary cathode material as described above in a lithium-ion battery.

[0035] Further, the application includes: mixing the above-mentioned cathode material with a conductive agent and a binder, coating, and slicing for use as a battery cathode. The conductive agent and the binder can be various conductive agents and binders commonly used in the art. For example, the conductive agent can be selected from at least one of acetylene black, Ketjen black, graphite, carbon nanotubes, and graphene. The binder can be selected from at least one of polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), and sodium carboxymethyl cellulose (CMC). The amounts of the conductive agent and the binder can also be conventional amounts in the art. For example, the mass ratio of the cathode material: conductive agent: binder is 0.8 - 0.96∶0.1 - 0.02∶0.1 - 0.02.

[0036] Further, the lithium-ion battery includes a cathode, an anode, a separator, and an electrolyte. There are no particular limitations on the anode, the separator, and the electrolyte, and those skilled in the art can reasonably select them without creative labor. For the sake of comparison, in the embodiments of the present invention, metallic lithium is used as the anode, a 16μm polyethylene microporous membrane of Jinhui Hi-Tech is used as the separator, and a 1mol / L LiPF6 solution is used as the electrolyte, and the solvent is a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) with a volume ratio of 3∶7.

[0037] Further, the battery is assembled in an inert atmosphere glove box, and the moisture and oxygen content in the glove box are less than 0.1 ppm. There are no particular limitations on the battery model. For the sake of comparison, in the embodiments of the present invention, the 2016-type button cell is commonly used, and the electrochemical performance is tested on a Blue Power battery test system, and the electrochemical test temperature is 30°C.

[0038] The methods for preparing lithium batteries using cathode materials are well known in the field and will not be described here.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) This invention provides a novel single-crystal ternary cathode material, which, compared with general single-crystal cathode materials, has a lower lithium-nickel mixing degree. The XRD results show a larger I(003) / I(104) peak intensity ratio and a larger c / a ratio in the XRD-refined lattice parameters, indicating that the prepared ternary material has better crystallinity and stronger layered characteristics. When applied to lithium-ion batteries, this cathode material imparts higher discharge capacity and initial coulombic efficiency.

[0041] (2) In the preparation process of the single-crystal ternary cathode material of the present invention, the calcination adopts a three-stage programmed temperature rise method. By controlling the parameters such as calcination time and calcination temperature in the heating program, the lithium salt and precursor hydroxide are melted and reacted in the first stage of calcination. In the second stage of calcination, the highest T2 temperature is used to ensure the formation of single crystal morphology of cathode material, and the shortest t2 time is used to ensure the lowest energy consumption required for material preparation. In the third stage of calcination, the lithium-nickel mixing degree of cathode material is effectively reduced by the moderate T3 temperature and the relatively long t3 time.

[0042] (3) The novel single-crystal ternary cathode material prepared by the present invention exhibits higher discharge capacity and first coulombic efficiency when applied to coin lithium batteries. Attached Figure Description

[0043] Figure 1 This is a SEM image of the single-crystal ternary cathode material prepared in Example 1 of the present invention;

[0044] Figure 2 The image shows the XRD pattern of the single-crystal ternary cathode material prepared in Example 1 of this invention.

[0045] Figure 3 The 0.1C charge-discharge curve of the battery obtained in Example 1 of this invention;

[0046] Figure 4 The circuit stability test curve of the battery obtained in Example 1 of the present invention is shown. Detailed Implementation

[0047] To facilitate understanding of the present invention, embodiments are provided below. However, those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as specific limitations on the invention. The endpoints of the ranges and any values ​​disclosed herein are not limited to those precise ranges or values; such ranges or values ​​should be understood to include values ​​close to them.

[0048] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by one of ordinary skill in the art. In case of conflict, the definitions in this specification shall prevail.

[0049] In the context of this specification, any two or more aspects of the present invention may be combined arbitrarily, and the resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0050] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are based on weight, unless being based on weight would not be in accordance with the common understanding of those skilled in the art.

[0051] In this invention, the scanning electron microscope (SEM) images were obtained using a Nova Nano450 field emission scanning electron microscope.

[0052] In this invention, the XRD pattern was obtained using a D8 ADVANCE X-ray diffractometer.

[0053] In this invention, the obtained XRD spectrum is refined using the Rietveld full-spectrum fitting refinement method with Topas software. When the confidence factor Rwp of the refined sample is less than or equal to 5%, the lithium-nickel mixing degree of the sample can be obtained.

[0054] In this invention, the size of the primary particles is measured using scanning electron microscopy images obtained through Nano measurer particle size analysis software.

[0055] The present invention will be described in detail below through embodiments.

[0056]

Example 1

[0057] (1) Preparation and evaluation of ternary cathode materials

[0058] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Mn 0.12 Add 5g of LiOH·H2O granules to (OH)2 and mix and grind thoroughly.

[0059] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and calcined in an oxygen atmosphere. The specific process was as follows: the heating rate was 5℃ / min, from 25℃ to 500℃, held for 7h, then the heating rate was 10℃ / min to 900℃, held for 4h, then the heating rate was 5℃ / min to 700℃, held for 12h, and then the powder was naturally cooled to below 100℃ and removed.

[0060] The powder obtained after high-temperature calcination was ball-milled for 2 hours to obtain the ternary cathode material.

[0061] Figure 1 The image shows a SEM image of the ternary cathode material obtained in Example 1. As can be seen from the image, the obtained ternary cathode material mainly exhibits a single-crystal morphology, and its primary particle size is 3.0-3.4 μm.

[0062] Figure 2 The image shows the XRD pattern of the ternary cathode material obtained in Example 1. As can be seen from the figure, the peak intensity ratio of I(003) / I(104) in the obtained ternary cathode material is 2.139, and the c / a ratio in its lattice parameters, obtained through refinement, is 4.9387. The lithium-nickel mixing degree is 1.722%, proving that the obtained high-nickel ternary cathode material has good crystallinity and a well-developed layered structure, while exhibiting a low lithium-nickel mixing degree.

[0063] (2) Electrochemical performance of cathode materials

[0064] The above-mentioned positive electrode material was mixed with conductive carbon and binder PVDF in NMP at a ratio of 0.9:0.05:0.05, coated onto aluminum foil, dried, sliced, and assembled into a 2016 type button cell in a glove box.

[0065] Figure 3 The figure shows the charge-discharge curves of the battery at a 0.1C rate. As can be seen from the figure, the discharge capacity of the obtained battery at a 0.1C rate is 181.1 mAh / g, and the initial coulombic efficiency is 85.66%.

[0066]

Example 2

[0067] (1) Preparation and evaluation of ternary cathode materials

[0068] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.12 Mn 0.05 Add 5g of LiOH·H2O granules to (OH)2 and mix and grind thoroughly.

[0069] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and calcined in an oxygen atmosphere. The heating rate was 5℃ / min, from 25℃ to 500℃, held for 7h, then heated to 900℃ at a rate of 10℃ / min, held for 4h, then cooled to 700℃ at a rate of 5℃ / min, held for 12h, and then allowed to cool naturally to below 100℃ before being removed.

[0070] The powder obtained after high-temperature calcination was ball-milled for 2 hours to obtain the ternary cathode material.

[0071] SEM images of the ternary cathode material obtained in Example 2 and Figure 1 Similarly, the primary particle size is 2.8-3.2 μm. XRD patterns are similar to... Figure 2 Similarly, the peak intensity ratio of I(003) / I(104) and the c / a ratio in the lattice parameters of the ternary cathode material were measured, and the specific results are shown in Table 1.

[0072] (2) Electrochemical performance of cathode materials

[0073] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0074] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0075]

Example 3

[0076] (1) Preparation and evaluation of ternary cathode materials

[0077] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Mn 0.12 Add 5g of LiOH·H2O granules to (OH)2 and mix and grind thoroughly.

[0078] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and calcined in an oxygen atmosphere. The heating rate was 5℃ / min, from 25℃ to 550℃, held for 6 hours, then heated to 800℃ at a rate of 10℃ / min, held for 3 hours, then cooled to 600℃ at a rate of 5℃ / min, held for 12 hours, and then allowed to cool naturally to below 100℃ before being removed.

[0079] The powder obtained after high-temperature calcination was ball-milled for 2 hours to obtain the ternary cathode material.

[0080] SEM images of the ternary cathode material obtained in Example 3 and Figure 1 Similarly, the primary particle size is 2.0-2.2 μm. XRD pattern and... Figure 2Similarly, the peak intensity ratio of I(003) / I(104) and the c / a ratio in the lattice parameters of the ternary cathode material were measured, and the specific results are shown in Table 1.

[0081] (2) Electrochemical performance of cathode materials

[0082] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0083] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0084]

Example 4

[0085] (1) Preparation and evaluation of ternary cathode materials

[0086] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.12 Mn 0.05 Add 5g of LiOH·H2O granules to (OH)2 and mix and grind thoroughly.

[0087] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and calcined in an oxygen atmosphere. The heating rate was 5℃ / min, from 25℃ to 500℃, held for 6 hours, then heated to 1050℃ at a heating rate of 8℃ / min, held for 5 hours, then cooled to 900℃ at a cooling rate of 5℃ / min, held for 15 hours, and then allowed to cool naturally to below 100℃ before being removed.

[0088] The powder obtained after high-temperature calcination was ball-milled for 8 hours to obtain the ternary cathode material.

[0089] SEM images of the ternary cathode material obtained in Example 4 and Figure 1 Similarly, the primary particle size is 4.6-4.9 μm. XRD pattern and... Figure 2 Similarly, the peak intensity ratio of I(003) / I(104) and the c / a ratio in the lattice parameters of the ternary cathode material were measured, and the specific results are shown in Table 1.

[0090] (2) Electrochemical performance of cathode materials

[0091] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0092] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0093]

Example 5

[0094] (1) Preparation and evaluation of ternary cathode materials

[0095] Take 10g of high-nickel ternary cathode material precursor Ni0.83 Co 0.05 Mn 0.12 Add 5.8g of LiOH·H2O granules to (OH)2 and mix and grind thoroughly;

[0096] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and calcined in an oxygen atmosphere. The specific process was as follows: the heating rate was 5℃ / min, from 25℃ to 550℃, held for 7h, then the heating rate was 8℃ / min to 950℃, held for 4h, then the heating rate was 5℃ / min to 700℃, held for 10h, and then the powder was naturally cooled to below 100℃ and removed.

[0097] The powder obtained after high-temperature calcination was ball-milled for 2 hours to obtain the ternary cathode material.

[0098] SEM images of the ternary cathode material obtained in Example 5 and Figure 1 Similarly, the primary particle size is 3.5-3.7 μm. XRD pattern and... Figure 2 Similarly, the peak intensity ratio of I(003) / I(104) and the c / a ratio in the lattice parameters of the ternary cathode material were measured, and the specific results are shown in Table 1.

[0099] (2) Electrochemical performance of cathode materials

[0100] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0101] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0102]

Example 6

[0103] (1) Preparation and evaluation of ternary cathode materials

[0104] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Mn 0.12 Add 4.6g of LiOH·H2O granules to (OH)2 and mix and grind thoroughly;

[0105] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and calcined in an oxygen atmosphere. The specific process was as follows: the heating rate was 5℃ / min, from 25℃ to 450℃, held for 7h, then the heating rate was 10℃ / min to 850℃, held for 4h, then the heating rate was 5℃ / min to 700℃, held for 15h, and then the powder was naturally cooled to below 100℃ and removed.

[0106] The powder obtained after high-temperature calcination was ball-milled for 2 hours to obtain the ternary cathode material.

[0107] SEM images of the ternary cathode material obtained in Example 6 and Figure 1 Similarly, the primary particle size is 3.2-3.6 μm. XRD patterns are similar to... Figure 2 Similarly, the peak intensity ratio of I(003) / I(104) and the c / a ratio in the lattice parameters of the ternary cathode material were measured, and the specific results are shown in Table 1.

[0108] (2) Electrochemical performance of cathode materials

[0109] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0110] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0111]

Example 7

[0112] (1) Preparation and evaluation of ternary cathode materials

[0113] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Al 0.12 Add 5g of LiOH·H2O granules to (OH)2 and mix and grind thoroughly.

[0114] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and calcined in an oxygen atmosphere. The specific process was as follows: the heating rate was 5℃ / min, from 25℃ to 500℃, held for 7h, then the heating rate was 10℃ / min to 900℃, held for 4h, then the heating rate was 5℃ / min to 700℃, held for 12h, and then the powder was naturally cooled to below 100℃ and removed.

[0115] The powder obtained after high-temperature calcination was ball-milled for 2 hours to obtain the ternary cathode material.

[0116] SEM images of the ternary cathode material obtained in Example 7 and Figure 1 Similarly, its primary particle size is 3.3-3.5 μm. XRD pattern and... Figure 2 Similarly, the peak intensity ratio of I(003) / I(104) and the c / a ratio in the lattice parameters of the ternary cathode material were measured, and the specific results are shown in Table 1.

[0117] (2) Electrochemical performance of cathode materials

[0118] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0119] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0120] Comparative Example 1

[0121] (1) Preparation and evaluation of ternary cathode materials

[0122] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Mn 0.12 Add 5g of LiOH·H2O granules to (OH)2 and mix and grind thoroughly.

[0123] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and calcined in an oxygen atmosphere. The heating rate was 5℃ / min, from 25℃ to 550℃, held for 7h, and then heated to 900℃ at a heating rate of 10℃ / min, held for 12h, and then cooled naturally to below 100℃ before being removed.

[0124] The powder obtained after high-temperature calcination was ball-milled for 2 hours to obtain the ternary cathode material.

[0125] SEM images of the ternary cathode material obtained in Comparative Example 1 and Figure 1 Similarly, the primary particle size is 3.5-3.8 μm. XRD pattern and... Figure 2 Similarly, the peak intensity ratio of I(003) / I(104) and the c / a ratio in the lattice parameters of the ternary cathode material were measured, and the specific results are shown in Table 1.

[0126] (2) Electrochemical performance of cathode materials

[0127] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0128] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0129] Comparative Example 2

[0130] (1) Preparation and evaluation of ternary cathode materials

[0131] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.12 Mn 0.05 Add 5g of LiOH·H2O granules to (OH)2 and mix and grind thoroughly.

[0132] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and calcined in an oxygen atmosphere. The heating rate was 5℃ / min, from 25℃ to 550℃, held for 7h, and then heated to 930℃ at a heating rate of 8℃ / min, held for 12h, and then cooled naturally to below 100℃ before being removed.

[0133] The powder obtained after high-temperature calcination was ball-milled for 2 hours to obtain the ternary cathode material.

[0134] SEM images of the ternary cathode material obtained in Comparative Example 2 and Figure 1 Similarly, the primary particle size is 4.0-4.5 μm. XRD pattern and... Figure 2 Similarly, the peak intensity ratio of I(003) / I(104) and the c / a ratio in the lattice parameters of the ternary cathode material were measured, and the specific results are shown in Table 1.

[0135] (2) Electrochemical performance of cathode materials

[0136] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0137] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0138] Comparative Example 3

[0139] (1) Preparation and evaluation of ternary cathode materials

[0140] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Mn 0.12 Add 5g of LiOH·H2O granules to (OH)2 and mix and grind thoroughly.

[0141] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and calcined in an oxygen atmosphere. The specific process was as follows: the heating rate was 5℃ / min, from 25℃ to 500℃, held for 7h, then heated to 700℃ at a heating rate of 10℃ / min, held for 4h, then heated to 900℃ at a heating rate of 10℃ / min, held for 12h, and then naturally cooled to below 100℃ before being taken out.

[0142] The powder obtained after high-temperature calcination was ball-milled for 2 hours to obtain the ternary cathode material.

[0143] SEM images of the ternary cathode material obtained in Comparative Example 3 and Figure 1 Similarly, the primary particle size is 3.7-3.9 μm. XRD pattern and... Figure 2 Similarly, the peak intensity ratio of I(003) / I(104) and the c / a ratio in the lattice parameters of the ternary cathode material were measured, and the specific results are shown in Table 1.

[0144] (2) Electrochemical performance of cathode materials

[0145] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0146] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0147] Comparative Example 4

[0148] (1) Preparation and evaluation of ternary cathode materials

[0149] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Mn 0.12 Add 5g of LiOH·H2O granules to (OH)2 and mix and grind thoroughly.

[0150] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and calcined in an oxygen atmosphere. The specific process was as follows: the heating rate was 5℃ / min, from 25℃ to 700℃, held for 7h, then the heating rate was 10℃ / min to 900℃, held for 4h, then the heating rate was 10℃ / min to 500℃, held for 12h, and then the powder was naturally cooled to below 100℃ and removed.

[0151] The powder obtained after high-temperature calcination was ball-milled for 2 hours to obtain the ternary cathode material.

[0152] SEM images of the ternary cathode material obtained in Comparative Example 4 and Figure 1 Similarly, the primary particle size is 4.3-4.6 μm. XRD pattern and... Figure 2 Similarly, the peak intensity ratio of I(003) / I(104) and the c / a ratio in the lattice parameters of the ternary cathode material were measured, and the specific results are shown in Table 1.

[0153] (2) Electrochemical performance of cathode materials

[0154] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0155] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0156] Table 1. Physicochemical properties of the single-crystal ternary cathode materials obtained in each example.

[0157] sample Ternary cathode material I(003) / I(104) c / a Lithium-nickel mixing degree Example 1 <![CDATA[LiNi 0.83 What 0.05 Mn 0.12 O2]]> 2.139 4.9387 1.722％ Example 2 <![CDATA[LiNi 0.83 What 0.12 Mn 0.05 O2]]> 2.045 4.9374 2.437％ Example 3 <![CDATA[LiNi 0.83 What 0.05 Mn 0.12 O2]]> 1.936 4.9380 1.938％ Example 4 <![CDATA[LiNi 0.83 What 0.12 Mn 0.05 O2]]> 2.064 4.9367 3.184％ Example 5 <![CDATA[LiNi 0.83 What 0.05 Mn 0.12 O2]]> 2.125 4.9394 1.380％ Example 6 <![CDATA[LiNi 0.83 What 0.05 Mn 0.12 O2]]> 2.129 4.9389 1.829％ Example 7 <![CDATA[LiNi 0.83 Co 0.05 Al 0.12 O2]]> 1.925 4.9374 2.764％ Comparative Example 1 <![CDATA[LiNi 0.83 What 0.05 Mn 0.12 O2]]> 1.701 4.9359 6.722％ Comparative Example 2 <![CDATA[LiNi 0.83 What 0.12 Mn 0.05 O2]]> 1.082 4.9266 14.61％

[0158]

[0159] Table 2 shows the electrochemical performance test results of the single-crystal ternary cathode materials obtained in each example.

[0160]

[0161] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A single-crystal ternary cathode material with the chemical formula Li x Ni y Co z M a O b Where M is at least one of Mn and Al; 0.9≤x<1.1, 0.8≤y≤0.95, 0<z≤0.05, 0<a≤0.15, and the proportion of oxygen element conforms to the principle of electroneutrality based on the valence state and content of different elements; in the cathode material, the lithium-nickel mixing degree s is less than 2%; The preparation process of the single-crystal ternary cathode material includes the following steps: The ternary cathode material precursor is mixed with a lithium source, calcined, and crushed to obtain the single-crystal ternary cathode material. The ternary cathode material precursor is a hydroxide precursor containing nickel-cobalt-manganese, nickel-cobalt-aluminum, or nickel-cobalt-manganese-aluminum. The calcination adopts a three-stage programmed temperature control calcination. The first stage calcination temperature T1 is 450-550℃, the time t1 is 5-7 hours, and the heating rate is 2-8℃ / min. The second stage calcination temperature T2 is 850-1000℃, the time t2 is 0.5-4 hours, and the heating rate is 2-10℃ / min. The third stage calcination temperature T3 is 700-800℃, the time t3 is 9-15 hours, and the cooling rate is 2-10℃ / min. The calcination temperature and time follow the rule t3>t1>t2, and T2>T3>T1.

2. The single-crystal ternary cathode material according to claim 1, characterized in that: In the single-crystal ternary cathode material, the size of the primary particles is 2.0-5.0 μm.

3. The single-crystal ternary cathode material according to claim 2, characterized in that: In the single-crystal ternary cathode material, the size of the primary particles is 3.0-5.0 μm.

4. The single-crystal ternary cathode material according to claim 1, characterized in that: In the XRD pattern of the single-crystal ternary cathode material, the diffraction peak intensities I(003) and I(104) of the crystal plane (003) and crystal plane (104) satisfy the following relationship: I(003) / I(104) is greater than 1.

800.

5. The single-crystal ternary cathode material according to claim 4, characterized in that: In the XRD pattern of the single-crystal ternary cathode material, the diffraction peak intensities I(003) and I(104) of the crystal plane (003) and crystal plane (104) satisfy the following relationship: I(003) / I(104) is greater than 1.

900.

6. The single-crystal ternary cathode material according to claim 5, characterized in that: In the XRD pattern of the single-crystal ternary cathode material, the diffraction peak intensities I(003) and I(104) of the crystal plane (003) and crystal plane (104) satisfy the following relationship: I(003) / I(104) is greater than 2.

000.

7. The single-crystal ternary cathode material according to claim 1, characterized in that: In the single-crystal ternary cathode material, the c / a ratio in the lattice parameters is greater than 4.9350.

8. The single-crystal ternary cathode material according to claim 7, characterized in that: In the single-crystal ternary cathode material, the c / a ratio in the lattice parameters is greater than 4.9365.

9. The single-crystal ternary cathode material according to claim 8, characterized in that: In the single-crystal ternary cathode material, the c / a ratio in the lattice parameters is greater than 4.9380.

10. The preparation process of the single-crystal ternary cathode material according to any one of claims 1-9, comprising the following steps: The ternary cathode material precursor is mixed with a lithium source, calcined, and crushed to obtain the single-crystal ternary cathode material. The ternary cathode material precursor is a hydroxide precursor containing nickel-cobalt-manganese, nickel-cobalt-aluminum, or nickel-cobalt-manganese-aluminum. The calcination adopts a three-stage programmed temperature control calcination. The first stage calcination temperature T1 is 450-550℃, the time t1 is 5-7 hours, and the heating rate is 2-8℃ / min. The second stage calcination temperature T2 is 850-1000℃, the time t2 is 0.5-4 hours, and the heating rate is 2-10℃ / min. The third stage calcination temperature T3 is 700-800℃, the time t3 is 9-15 hours, and the cooling rate is 2-10℃ / min. The calcination temperature and time follow the rule t3>t1>t2, and T2>T3>T1.

11. The preparation process according to claim 10, characterized in that: The lithium source is one or more of anhydrous lithium hydroxide, lithium hydroxide monohydrate, lithium carbonate, lithium phosphate, and lithium oxalate.

12. The preparation process according to claim 11, characterized in that: The lithium source is one or more of anhydrous lithium hydroxide and lithium hydroxide monohydrate.

13. The preparation process according to claim 10, characterized in that: The chemical formula of the ternary cathode material precursor is Ni. y Co z M a (OH)2, wherein M is at least one of Mn and Al; 0.8≤y≤0.95, 0<z≤0.05, 0<a≤0.15, and y+z+a=1.

14. The preparation process according to claim 10, characterized in that: The molar ratio of the lithium source to the ternary cathode material precursor is 1:1 to 1.3:1; And / or, the crushing method is air jet crushing or ball milling, and the crushing time is 2-10 hours.

15. The preparation process according to claim 14, characterized in that: The molar ratio of the lithium source to the ternary cathode material precursor is 1.05:1 to 1.2:

1.

16. The application of the single-crystal ternary cathode material according to any one of claims 1-9 in lithium-ion batteries.

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