A high-nickel ternary positive electrode material, a preparation method and application thereof

Abstract

The application discloses a high-nickel ternary positive electrode material and a preparation method and application thereof. x Ni y Co z M a N b O c , M is at least one of Mn and Al, N is at least one of Ti, V, Nb, Zr, Ta, W or Mo, 0.9<=x<1.2, 0.6<=y<=0.95, 0

Description

Technical Field

[0001] This invention relates to the field of lithium-ion batteries, specifically to a high-nickel ternary cathode material, its preparation method, and its application. Background Technology

[0002] Since the first commercialization of lithium-ion batteries by Sony in the 1990s, the development of lithium-ion batteries with higher energy density has attracted widespread attention. Driven by high energy density, high-nickel ternary cathode materials with high specific capacity have become the focus of attention. High-nickel ternary cathode materials are composed of alternating layers of lithium atoms and transition metal atoms. However, because the radius of divalent nickel ions is close to that of lithium ions, lithium-nickel mixing easily occurs during material synthesis and electrochemical reactions, leading to a significant decrease in the material's structural stability, initial coulombic efficiency, and charge / discharge capacity.

[0003] Traditional polycrystalline high-nickel ternary cathode materials have numerous grain boundaries in their structure, which easily lead to side reactions with the electrolyte during electrochemical reactions. Furthermore, they are prone to secondary spherical cracking during long-term cycling, causing rapid performance degradation. Therefore, monocrystalline high-nickel ternary cathode materials have become a popular research area. Monocrystalline materials have larger primary particles and smoother particle surfaces, resulting in significantly better structural stability and long-term cycling stability compared to polycrystalline materials. CN107910534A discloses a solid-state preparation method for NCM811 type high-nickel ternary cathode materials, including raw material mixing, three-stage primary sintering, coating with a composite coating agent, secondary sintering, and post-sintering treatment. However, for monocrystalline materials, on the one hand, the preparation process requires higher calcination temperatures, which can easily lead to lithium-nickel mixing, negatively impacting the material's charge / discharge specific capacity and initial coulombic efficiency. On the other hand, the larger primary particle size reduces the lithium-ion insertion / extraction kinetics, hindering the material's discharge specific capacity and rate performance. Summary of the Invention

[0004] To address the problem of poor electrochemical performance caused by high lithium-nickel mixing degree and large particle size in existing single-crystal cathode materials, this invention provides a high-nickel ternary cathode material, its preparation method, and its application. The cathode material of this invention can significantly improve the discharge specific capacity and first coulombic efficiency of lithium batteries.

[0005] The first aspect of this invention provides a high-nickel ternary cathode material with the chemical formula Li. x Ni y Co z M a N b O cM is at least one of Mn and Al, and N is at least one of Ti, V, Nb, Zr, Ta, W, or Mo, preferably at least one of Nb, W, Ti, or Mo; 0.9≤x<1.2, 0.6≤y≤0.95, 0<z≤0.2, 0<a≤0.2, 0<b≤0.02, and the values ​​of x, y, z, a, b, and c conform to the principle of electroneutrality; the cathode material has a single crystal morphology, the average size of the primary particles is 0.20-1.50 micrometers, and the c / a ratio in the lattice parameters is greater than 4.9360.

[0006] In the above technical solution, the cathode material has a single crystal morphology, and the average size of the primary particles is 0.20-0.95 micrometers, preferably 0.30-0.90 micrometers.

[0007] In the above technical solution, the positive electrode material has the following properties: 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] In the above technical solution, the c / a ratio in the lattice parameters of the cathode material is greater than 4.9370.

[0009] In the above technical solution, the lithium-nickel mixing degree in the XRD refinement results of the cathode material is greater than 3% and less than 10%, preferably, the lithium-nickel mixing degree is greater than 3% and less than 6%.

[0010] A second aspect of this invention provides a method for preparing a high-nickel ternary cathode material, comprising:

[0011] A high-nickel ternary cathode material precursor, a lithium source, and a modifier are mixed, calcined, and crushed to obtain the cathode material.

[0012] In the above technical solution, the lithium source is one or more of anhydrous lithium hydroxide, lithium hydroxide monohydrate, lithium carbonate, lithium phosphate, or lithium oxalate, preferably at least one of anhydrous lithium hydroxide or lithium hydroxide monohydrate.

[0013] In the above technical solution, the high-nickel 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, 0.9≤x<1.1, 0.8≤y≤0.95, 0<z≤0.15, 0<a≤0.15, and y+z+a=1; more preferably, 0.9≤x<1.1, 0.8≤y≤0.95, 0<z≤0.05, 0<a≤0.15, and y+z+a=1.

[0014] In the above technical solution, the modifier is one or more of TiO2, V2O5, Nb2O5, ZrO2, Ta2O5, WO3 or MoO3, preferably one or more of TiO2, Nb2O5, WO3 or MoO3.

[0015] In the above technical solution, the molar ratio of lithium source to high-nickel ternary cathode material precursor is 1:1 to 1.3:1, preferably 1.05:1 to 1.2:1.

[0016] In the above technical solution, the molar ratio of the modifier to the high-nickel ternary cathode material precursor is 0.002:1 to 0.02:1, preferably 0.005:1 to 0.01:1.

[0017] In the above technical solution, the calcination adopts a three-stage temperature-controlled calcination process, wherein the temperature T1 of the first stage calcination is 400-600℃ and the calcination time t1 is 4-7 hours, the temperature T2 of the second stage calcination is 800-1100℃ and the calcination time t2 is 0.1-6 hours, and the temperature T3 of the third stage calcination is 600-900℃ and the calcination time t3 is 6-18 hours.

[0018] In the above technical solution, 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.

[0019] In the above technical solution, 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.

[0020] In the above technical solution, 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.

[0021] In the above technical solution, during the three-stage programmed 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 of t3 > t1 > t2 and T2 > T3 > T1.

[0022] In the above technical solution, during the three-stage programmed calcination process, the calcination atmosphere is one of nitrogen, air or high-purity oxygen. Preferably, the calcination atmosphere is one of air or high-purity oxygen.

[0023] In the above technical solution, the mixing is carried out by a conventional physical mixing method to make the ternary cathode material precursor and the lithium source fully contact, such as grinding.

[0024] In the above technical solution, the crushing method is a method such as air flow crushing or ball milling crushing, and the crushing time is 2 - 10 hours, preferably 4 - 8 hours.

[0025] In the above technical solution, for the high-nickel ternary cathode material, its chemical formula is Li x Ni y Co z M a N b O c , where M is at least one of Mn and Al, N is at least one of Ti, V, Nb, Zr, Ta, W or Mo, preferably at least one of Nb, W, Ti or Mo; 0.9 ≤ x < 1.2, 0.6 ≤ y ≤ 0.95, 0 < z ≤ 0.2, 0 < a ≤ 0.2, 0 < b ≤ 0.02, and the values of x, y, z, a, b, c conform to the principle of electroneutrality.

[0026] In the above technical solution, in the 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.

[0027] In the above technical solution, the cathode material has a single crystal morphology, and the average size of the primary particles is 0.20 - 1.50 μm, preferably 0.20 - 0.95 μm, and further preferably 0.30 - 0.90 μm.

[0028] In the above technical solution, in the cathode material, the c / a ratio in the lattice parameters is greater than 4.936, preferably, the c / a ratio is greater than 4.937.

[0029] In the above technical solution, in the XRD refinement result of the cathode material, the lithium-nickel mixing degree is greater than 3% and less than 10%, preferably, the lithium-nickel mixing degree is greater than 3% and less than 6%.

[0030] The third aspect of this invention provides the application of the high-nickel ternary cathode material as described above in lithium-ion batteries.

[0031] Further, the application includes: mixing the above-mentioned positive electrode material with a conductive agent and a binder, coating it, and slicing it for use as a battery positive electrode. The conductive agent and binder can be various conductive agents and binders conventionally 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 binder can also be conventional amounts used in the art; for example, the mass ratio of positive electrode material: conductive agent: binder is 0.8–0.96:0.1–0.02:0.1–0.02.

[0032] Furthermore, the lithium-ion battery includes a positive electrode, a negative electrode, a separator, and an electrolyte. There are no particular limitations on the negative electrode, separator, and electrolyte; those skilled in the art can choose them reasonably without inventive effort. For comparison, in this embodiment of the invention, metallic lithium is used as the negative electrode, a 16μm polyethylene microporous membrane from Jinhui High-Tech is used as the separator, and a 1mol / L LiPF6 solution is used as the electrolyte. The solvent is a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 3:7.

[0033] Furthermore, the battery is assembled in an inert atmosphere glove box, where the moisture and oxygen content is below 0.1 ppm. There are no particular restrictions on the battery type; for comparison, the 2016 coin cell is commonly used in this embodiment of the invention. Electrochemical performance is tested on a Blue Battery testing system at a temperature of 30°C.

[0034] The methods for preparing lithium batteries using cathode materials are well known in the field and will not be described here.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) This invention provides a high-nickel ternary cathode material with a single crystal morphology, small primary particle size, moderate lithium-nickel mixing degree, and a large c / a ratio in the refined lattice parameters obtained by XRD, indicating that the prepared ternary material has good crystallinity and layered structure, which can effectively improve the discharge specific capacity and first coulombic efficiency of the single crystal cathode material.

[0037] (2) The high-nickel ternary cathode material of this invention is prepared by introducing ion modification in a three-stage programmed temperature-controlled calcination process. While the lithium-nickel mixing degree increases to some extent due to the introduction of modifying elements into the system, the primary particle size is relatively reduced, shortening the lithium-ion transport path during charging and discharging, effectively improving the lithium-ion insertion / extraction kinetics rate, thereby increasing the discharge specific capacity and initial coulombic efficiency of the single-crystal cathode material. Specifically, by controlling parameters such as calcination time and calcination temperature in the temperature-controlled process, the first stage of calcination promotes the melting and initial reaction of lithium salt and precursor hydroxide. In the second stage of calcination, the highest T2 temperature ensures the formation of the single-crystal morphology of the cathode material, while the shortest t2 time ensures the lowest energy consumption required for material preparation. In the third stage of calcination, a moderate T3 temperature and a relatively long t3 time further promote the refinement of the primary particles in the bulk phase of the cathode material by the modified ions, ensuring that the lithium-nickel mixing degree is not too high.

[0038] (3) The novel single-crystal ternary cathode material prepared by the present invention exhibits higher discharge specific capacity and first coulombic efficiency when applied to coin lithium batteries. Attached Figure Description

[0039] Figure 1 This is a SEM image of the high-nickel ternary cathode material prepared in Example 1 of the present invention;

[0040] Figure 2 The 0.1C charge-discharge curve of the battery in Embodiment 1 of the present invention;

[0041] Figure 3 This is a SEM image of the high-nickel ternary cathode material prepared in Comparative Example 1 of this invention;

[0042] Figure 4 This is the 0.1C charge / discharge curve of the battery in Comparative Example 1 of the present invention. Detailed Implementation

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] In this invention, the scanning electron microscope (SEM) images were obtained using a Nova Nano450 field emission scanning electron microscope.

[0048] In this invention, the XRD pattern was obtained using a D8 ADVANCE X-ray diffractometer.

[0049] 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.

[0050] In this invention, the average size of the primary particles is measured by scanning electron microscopy using Nano measurer particle size analysis software, and the average value is calculated for the data whose size is in the 10%-90% percentile of the measurement results.

[0051] The present invention will be described in detail below through embodiments.

[0052]

Example 1

[0053] (1) Preparation and evaluation of ternary cathode materials

[0054] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Mn 0.12 Add 5g of LiOH·H2O powder and 0.15g of Nb2O5 powder to (OH)2 and mix and grind thoroughly;

[0055] The homogeneous powder obtained above was subjected to high-temperature treatment in a tube furnace and sintered in an oxygen atmosphere. The heating rate was 5℃ / min, from 30℃ to 500℃, held for 7h, then heated to 900℃ at a heating rate of 10℃ / min, held for 4h, then cooled to 700℃ at a cooling rate of 5℃ / min, held for 12h, and then allowed to cool naturally to below 100℃ before being removed.

[0056] The powder obtained after high-temperature calcination was ball-milled for 4 hours to obtain high-nickel ternary cathode material.

[0057] Figure 1 The image shows a SEM image of the high-nickel ternary cathode material obtained in Example 1. As can be seen from the image, the obtained high-nickel ternary cathode material mainly exhibits a single-crystal morphology, and the average size of the primary particles is 0.90 μm.

[0058] (2) Electrochemical performance of cathode materials

[0059] 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.

[0060] Figure 2 The figure shows the charge-discharge curves of the battery assembled using the above cathode material at a 0.1C rate. As can be seen from the figure, the discharge capacity of the battery at a 0.1C rate is 189.8 mAh / g, and the initial coulombic efficiency is 86.17%.

[0061]

Example 2

[0062] (1) Preparation and evaluation of ternary cathode materials

[0063] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Mn 0.12 Add 5g of LiOH·H2O powder and 0.25g of Ta2O5 powder to (OH)2 and mix and grind thoroughly;

[0064] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and sintered in an oxygen atmosphere. The heating rate was 5℃ / min, from 30℃ 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.

[0065] The powder obtained after high-temperature calcination was ball-milled for 4 hours to obtain high-nickel ternary cathode material.

[0066] SEM images of the high-nickel ternary cathode material obtained in Example 2 and Figure 1 Similarly, the average size of the primary particles is 0.80 μm.

[0067] (2) Electrochemical performance of cathode materials

[0068] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0069] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0070]

Example 3

[0071] (1) Preparation and evaluation of ternary cathode materials

[0072] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Mn 0.12 Add 5g of LiOH·H2O powder and 0.08g of TiO2 powder to (OH)2 and mix and grind thoroughly;

[0073] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and sintered in an oxygen atmosphere. The heating rate was 5℃ / min, from 25℃ to 550℃, held for 7h, then heated to 900℃ at a rate of 10℃ / min, held for 3h, then cooled to 750℃ at a rate of 5℃ / min, held for 12h, and then allowed to cool naturally to below 100℃ before being removed.

[0074] The powder obtained after high-temperature calcination was ball-milled for 4 hours to obtain high-nickel ternary cathode material.

[0075] SEM images of the high-nickel ternary cathode material obtained in Example 3 and Figure 1 Similarly, the average size of the primary particles is 0.83 μm.

[0076] (2) Electrochemical performance of cathode materials

[0077] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0078] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0079]

Example 4

[0080] (1) Preparation and evaluation of ternary cathode materials

[0081] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.12 Mn 0.05 Add 5g of LiOH·H2O powder and 0.15g of Nb2O5 powder to (OH)2 and mix and grind thoroughly;

[0082] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and sintered in an oxygen atmosphere. The heating rate was 5℃ / min, from 25℃ to 500℃, held for 7 hours, then heated to 900℃ at a rate of 10℃ / min, held for 4 hours, and then cooled to 700℃ at a rate of 5℃ / min, held for 12 hours, and finally allowed to cool naturally to below 100℃ before being removed.

[0083] The powder obtained after high-temperature calcination was ball-milled for 4 hours to obtain high-nickel ternary cathode material.

[0084] SEM images of the high-nickel ternary cathode material obtained in Example 4 and Figure 1 Similarly, the average size of the primary particles is 0.86 μm.

[0085] (2) Electrochemical performance of cathode materials

[0086] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0087] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0088]

Example 5

[0089] (1) Preparation and evaluation of ternary cathode materials

[0090] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Mn 0.12 Add 5g of LiOH·H2O powder and 0.27g of WO3 powder to (OH)2 and mix and grind thoroughly;

[0091] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and sintered in an oxygen atmosphere. The heating rate was 5℃ / min, from 30℃ to 500℃, held for 7h, then heated to 900℃ at a rate of 10℃ / min, held for 2h, then cooled to 700℃ at a rate of 5℃ / min, held for 15h, and then allowed to cool naturally to below 100℃ before being removed.

[0092] The powder obtained after high-temperature calcination was ball-milled for 8 hours to obtain high-nickel ternary cathode material.

[0093] SEM images of the high-nickel ternary cathode material obtained in Example 5 and Figure 1 Similarly, the average size of the primary particles is 0.62 μm.

[0094] (2) Electrochemical performance of cathode materials

[0095] The lithium battery was assembled according to the method described in Example 5, and its electrochemical performance was tested.

[0096] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0097]

Example 6

[0098] (1) Preparation and evaluation of ternary cathode materials

[0099] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Mn 0.12 Add 5g of LiOH·H2O powder and 0.18g of MoO3 powder to (OH)2 and mix and grind thoroughly;

[0100] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and sintered in an oxygen atmosphere. The heating rate was 5℃ / min, from 30℃ to 500℃, held for 7h, then heated to 900℃ at a rate of 10℃ / min, held for 1h, 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.

[0101] The powder obtained after high-temperature calcination was ball-milled for 8 hours to obtain high-nickel ternary cathode material.

[0102] SEM images of the high-nickel ternary cathode material obtained in Example 6 and Figure 1 Similarly, the average size of the primary particles is 0.38 μm.

[0103] (2) Electrochemical performance of cathode materials

[0104] The lithium battery was assembled according to the method described in Example 6, and its electrochemical performance was tested.

[0105] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0106]

Example 7

[0107] (1) Preparation and evaluation of ternary cathode materials

[0108] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Al 0.12 Add 5g of LiOH·H2O powder and 0.08g of TiO2 powder to (OH)2 and mix and grind thoroughly;

[0109] The obtained homogeneous powder was subjected to high-temperature treatment in a tube furnace and sintered in an oxygen atmosphere. The heating rate was 5℃ / min, from 25℃ to 550℃, held for 7h, then heated to 900℃ at a rate of 10℃ / min, held for 3h, then cooled to 750℃ at a rate of 5℃ / min, held for 12h, and then allowed to cool naturally to below 100℃ before being removed.

[0110] The powder obtained after high-temperature calcination was ball-milled for 4 hours to obtain high-nickel ternary cathode material.

[0111] SEM and SEM images of the high-nickel ternary cathode material obtained in Example 7 Figure 1 Similarly, the average size of the primary particles is 0.76 μm.

[0112] (2) Electrochemical performance of cathode materials

[0113] The lithium battery was assembled according to the method described in Example 7, and its electrochemical performance was tested.

[0114] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0115] Comparative Example 1

[0116] (1) Preparation and evaluation of ternary cathode materials

[0117] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Mn 0.12 Add 5g of LiOH·H2O powder and 0.05g of MgO powder to (OH)2 and mix and grind thoroughly;

[0118] The homogeneous powder obtained above was subjected to high-temperature treatment in a tube furnace and sintered in an oxygen atmosphere. The heating rate was 5℃ / min, from 30℃ 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.

[0119] The powder obtained after high-temperature calcination was ball-milled for 4 hours to obtain high-nickel ternary cathode material.

[0120] Figure 3 The image shows the SEM image of Comparative Example 1. As can be seen from the image, the obtained high-nickel ternary cathode material mainly exhibits a single-crystal morphology, with an average primary particle size of 3.40 μm.

[0121] (2) Electrochemical performance of cathode materials

[0122] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0123] Figure 4 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 145.2 mAh / g, and the initial coulombic efficiency is 74.59%.

[0124] Comparative Example 2

[0125] (1) Preparation and evaluation of ternary cathode materials

[0126] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.12 Mn 0.05 Add 5g of LiOH·H2O granules and 0.15g of Nb2O5 powder to (OH)2 and mix and grind thoroughly;

[0127] The homogeneous powder obtained above was subjected to high-temperature treatment in a tube furnace and sintered in an oxygen atmosphere. The heating rate was 5℃ / min, from 30℃ to 550℃, held for 7h, and then heated to 930℃ at a heating rate of 10℃ / min, held for 12h, and then naturally cooled to below 100℃ before being removed.

[0128] The powder obtained after high-temperature calcination was ball-milled for 4 hours to obtain high-nickel ternary cathode material.

[0129] SEM images of the high-nickel ternary cathode material obtained in Comparative Example 2 and Figure 1 Similarly, the average size of the primary particles is 2.50 μm.

[0130] (2) Electrochemical performance of cathode materials

[0131] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0132] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0133] Comparative Example 3

[0134] (1) Preparation and evaluation of ternary cathode materials

[0135] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Mn 0.12 Add 5g of LiOH·H2O powder and 0.15g of Nb2O5 powder to (OH)2 and mix and grind thoroughly;

[0136] 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 30℃ 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.

[0137] The powder obtained after high-temperature calcination was ball-milled for 4 hours to obtain the ternary cathode material.

[0138] SEM images of the ternary cathode material obtained in Comparative Example 3 and Figure 1 Similarly, the average size of the primary particles is 2.10 μm.

[0139] (2) Electrochemical performance of cathode materials

[0140] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0141] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0142] Comparative Example 4

[0143] (1) Preparation and evaluation of ternary cathode materials

[0144] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Mn 0.12 Add 5g of LiOH·H2O powder and 0.15g of Nb2O5 powder to (OH)2 and mix and grind thoroughly;

[0145] 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 30℃ to 700℃, held for 7h, then heated to 1000℃ at a heating rate of 10℃ / min, held for 4h, then cooled to 500℃ at a cooling rate of 10℃ / min, held for 12h, and then naturally cooled to below 100℃ before being taken out.

[0146] The powder obtained after high-temperature calcination was ball-milled for 4 hours to obtain the ternary cathode material.

[0147] SEM images of the ternary cathode material obtained in Comparative Example 4 and Figure 1 Similarly, the average size of the primary particles is 2.80 μm.

[0148] (2) Electrochemical performance of cathode materials

[0149] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0150] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0151] Comparative Example 5

[0152] (1) Preparation and evaluation of ternary cathode materials

[0153] Take 10g of high-nickel ternary cathode material precursor Ni 0.83 Co 0.05 Mn 0.12Add 5g of LiOH·H2O powder to (OH)2 and mix and grind thoroughly.

[0154] The homogeneous powder obtained above was subjected to high-temperature treatment in a tube furnace and sintered in an oxygen atmosphere. The heating rate was 5℃ / min, from 30℃ to 500℃, held for 7h, then heated to 900℃ at a heating rate of 10℃ / min, held for 4h, then cooled to 700℃ at a cooling rate of 5℃ / min, held for 12h, and then allowed to cool naturally to below 100℃ before being removed.

[0155] The powder obtained after high-temperature calcination was ball-milled for 4 hours to obtain high-nickel ternary cathode material.

[0156] SEM images of the high-nickel ternary cathode material obtained in Comparative Example 5 and Figure 1 Similarly, the average size of the primary particles is 3.00 μm.

[0157] (2) Electrochemical performance of cathode materials

[0158] The lithium battery was assembled according to the method described in Example 1, and its electrochemical performance was tested.

[0159] The electrochemical performance was measured at a rate of 0.1C, and the specific results are shown in Table 2.

[0160] Table 1. Physicochemical properties of the high-nickel ternary cathode materials obtained in each example.

[0161] sample Chemical formula of cathode material c / a Lithium-nickel mixing degree Example 1 <![CDATA[Li[Ni 0.83 Co 0.05 Mr 0.12 ] 0.99 No 0.01 O2]]> 4.9379 4.831％ Example 2 <![CDATA[Li[Ni 0.83 Co 0.05 Mr 0.12 ] 0.99 Dad 0.01 O2]]> 4.9361 6.938％ Example 3 <![CDATA[Li[Ni 0.83 What 0.05 Mn 0.12 ] 0.99 Those 0.01 O2]]> 4.9387 5.045％ Example 4 <![CDATA[Li[Ni 0.83 Co 0.12 Mr 0.05 ] 0.99 No 0.01 O2]]> 4.9363 6.872％ Example 5 <![CDATA[Li[Ni 0.83 What 0.12 Mn 0.05 ] 0.985 IN 0.015 O2]]> 4.9382 5.117％ Example 6 <![CDATA[Li[Ni 0.83 Co 0.12 Mr 0.05 ] 0.985 Mo 0.015 O2]]> 4.9378 4.735％ Example 7 <![CDATA[Li[Ni 0.83 What 0.05 Al 0.12 ] 0.99 Those 0.01 O2]]> 4.9383 4.982％ Comparative Example 1 <![CDATA[Li[Ni 0.83 What 0.05 Mn 0.12 ] 0.99 Mg 0.01 O2]]> 4.9352 6.203％ Comparative Example 2 <![CDATA[Li[Ni 0.83 Co 0.05 Mr 0.12 ] 0.99 No 0.01 O2]]> 4.9279 12.968％ Comparative Example 3 <![CDATA[Li[Ni 0.83 Co 0.05 Mr 0.12 ] 0.99 No 0.01 O2]]> 4.9334 8.476％ Comparative Example 4 <![CDATA[Li[Ni 0.83 Co 0.05 Mr 0.12 ] 0.99 No 0.01 O2]]> 4.9261 10.042％ Comparative Example 5 <![CDATA[LiNi 0.83 What 0.05 Mn 0.12 O2]]> 4.9387 1.722％

[0162] Table 2 shows the electrochemical performance test results of the high-nickel ternary cathode materials obtained in each example.

[0163]

[0164]

[0165] 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 technical concept of the present invention, 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 high-nickel ternary cathode material with the chemical formula Li x Ni y Co z M a N b O c , where M is at least one of Mn and Al, and N is at least one of Ti, V, Nb, Zr, Ta, W, or Mo; 0.9 ≤ x < 1.2, 0.6 ≤ y ≤ 0.95, 0 < z ≤ 0.2, 0 < a ≤ 0.2, 0 < b ≤ 0.02, and the values of x, y, z, a, b, and c conform to the principle of electroneutrality; the cathode material has a single-crystal morphology, the average size of the primary particles is 0.20 - 1.50 microns, and the c / a ratio in the lattice parameters is greater than 4.9360; The preparation method of the high-nickel ternary cathode material includes the following steps: A high-nickel ternary cathode material precursor, a lithium source, and a modifier are mixed, calcined, and crushed to obtain the cathode material. The high-nickel 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 temperature-controlled calcination process. 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 heating rate is 2-10℃ / min. The calcination temperature and time follow the rule t3>t1>t2, and T2>T3>T1.

2. The high-nickel ternary cathode material according to claim 1, characterized in that: The chemical formula of high-nickel ternary cathode material is Li x Ni y Co z M a N b O c In this context, N is at least one of Nb, W, Ti, or Mo.

3. The high-nickel ternary cathode material according to claim 1, characterized in that: In the cathode material, 0.9≤x<1.1, 0.8≤y≤0.95, 0<z≤0.15, and 0<a≤0.

15.

4. The high-nickel ternary cathode material according to claim 3, characterized in that: In the cathode material, 0.9≤x<1.1, 0.8≤y≤0.95, 0<z≤0.05, and 0<a≤0.

15.

5. The high-nickel ternary cathode material according to claim 1, characterized in that: The average size of the primary particles is 0.20-0.95 micrometers.

6. The high-nickel ternary cathode material according to claim 5, characterized in that: The average size of the primary particles is 0.30-0.90 micrometers.

7. The high-nickel ternary cathode material according to claim 1, characterized in that: In the cathode material, the c / a ratio in the lattice parameters is greater than 4.9370.

8. The high-nickel ternary cathode material according to claim 1, characterized in that: In the XRD refinement results of the cathode material, the lithium-nickel mixing degree is greater than 3% and less than 10%.

9. The high-nickel ternary cathode material according to claim 8, characterized in that: In the XRD refinement results of the cathode material, the lithium-nickel mixing degree is greater than 3% and less than 6%.

10. A method for preparing the high-nickel ternary cathode material according to any one of claims 1-9, comprising the following steps: A high-nickel ternary cathode material precursor, a lithium source, and a modifier are mixed, calcined, and crushed to obtain the cathode material. The high-nickel 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 temperature-controlled calcination process. 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 heating rate is 2-10℃ / min. The calcination temperature and time follow the rule t3>t1>t2, and T2>T3>T1.

11. The preparation method 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, or lithium oxalate; And / or, the modifier is one or more of TiO2, V2O5, Nb2O5, ZrO2, Ta2O5, WO3 or MoO3.

12. The preparation method according to claim 11, characterized in that: The lithium source is one or more of anhydrous lithium hydroxide or lithium hydroxide monohydrate; And / or, the modifier is one or more of TiO2, Nb2O5, WO3 or MoO3.

13. The preparation method according to claim 10, characterized in that: The chemical formula of the high-nickel ternary cathode material precursor is 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.

14. The preparation method according to claim 13, characterized in that: The chemical formula of the high-nickel ternary cathode material precursor is Ni y Co z M a In (OH)2, 0.9≤x<1.1, 0.8≤y≤0.95, 0<z≤0.15, 0<a≤0.15, and y+z+a=1.

15. The preparation method according to claim 14, characterized in that: The chemical formula of the high-nickel ternary cathode material precursor is Ni y Co z M a In (OH)2, 0.9≤x<1.1, 0.8≤y≤0.95, 0<z≤0.05, 0<a≤0.15, and y+z+a=1.

16. The preparation method 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 molar ratio of the modifier to the high-nickel ternary cathode material precursor is 0.002:1 to 0.02:1; And / or, the crushing method is air jet crushing or ball milling, and the crushing time is 2-10 hours.

17. The preparation method according to claim 16, characterized in that: The molar ratio of the lithium source to the ternary cathode material precursor is 1.05:1 to 1.2:1; And / or, the molar ratio of the modifier to the high-nickel ternary cathode material precursor is 0.005:1 to 0.01:1; And / or, the crushing time is 4-8 hours.

18. The application of the high-nickel ternary cathode material according to any one of claims 1-9 in lithium-ion batteries.

Images