High voltage single crystal ternary cathode material, preparation method and application thereof

Abstract

The present invention discloses a high-voltage single-crystal ternary material, its preparation method, and its application. By using a low-melting-point flux to reduce the grain boundary fusion energy, pre-sintering at low temperature produces oriented microcrystalline nuclei. The oriented microcrystalline nuclei react with a structural stabilizer at high temperature to achieve oriented growth of the nuclei. A large-particle ternary material precursor with low activity is ball-milled into a high-activity precursor with the aid of a dispersant and a solvent, increasing the number of reactive sites between the precursor and the lithium salt. The resulting single-crystal ternary cathode material exhibits good particle size uniformity, relatively uniform distribution of transition metal elements within the grains, and oriented grain growth. It also exhibits a high compaction density, allowing the electrode to maintain coating integrity under high rolling strength, preventing grain boundary fracture. The material significantly outperforms conventional single-crystal ternary cathode materials in terms of capacity, high- and low-temperature cycling, and rate performance. The preparation method is simple, the equipment is highly versatile, and it is easy to scale up.

Description

Technical Field

[0001] The present invention relates to the field of preparation of lithium ion secondary battery electrode materials, and in particular to a high-voltage single crystal ternary positive electrode material, a preparation method thereof, and applications thereof. Background Art

[0002] Over the next 5-10 years, the power battery market will flourish, and demand for ternary materials for lithium-ion batteries will also increase. Based on the recent developments in lithium battery technology and its widespread global application, the future development of lithium battery cathode materials will primarily focus on "medium nickel high voltage" and "high nickel."

[0003] High-voltage single-crystal ternary materials have achieved a good balance in multiple dimensions such as economy, safety, energy density, and cycle life, and have obvious advantages over higher nickel materials in terms of watt-hour cost and cycle life. Market demand has increased sharply in recent years.

[0004] Medium-nickel materials primarily have two structures: agglomerates and single crystals. Agglomerates are secondary spheres composed of tiny primary particles. These spheres easily break during high-density charging and discharging, exacerbating side reactions and leading to poor thermal stability. Single-crystal ternary materials offer excellent particle size, dispersion, and mechanical strength. They prevent inter-particle breakage during charging and discharging, effectively reducing side reactions at the interface between the material and the electrolyte. This not only improves the ternary material's capacity at high voltages, but also effectively addresses issues such as poor high-temperature cycling, flatulence, and rapid capacity decay.

[0005] The current preparation of single-crystal ternary cathode materials faces several challenges: 1) Precursors require relatively high temperatures to form single-crystal structures; 2) Doping elements exhibit a gradient distribution from the surface to the bulk, resulting in uneven distribution and poor structural uniformity; and 3) Single-crystal materials prepared using conventional methods exhibit poor particle roundness and numerous agglomerates. Therefore, it is crucial to improve material synthesis techniques to achieve a more uniform distribution of transition metal elements and directional grain growth, thereby mitigating the microstructural collapse and grain boundary cracking that occur after long cycles at high temperatures and high voltages, and thereby significantly improving the electrochemical performance of single-crystal ternary cathode materials.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] In response to the technical problems raised by the above background technology, the purpose of the present invention is to provide a high-voltage single-crystal ternary positive electrode material and a preparation method thereof, which realizes the directional growth of grains through segmented sintering with flux and structural stabilizer. The prepared material has a high degree of single crystallinity, good roundness, and more uniform distribution of doping elements, which inhibits the side reaction between the material grains and the electrolyte caused by the cracking of the material grains after cycling, or improves the capacity and cycle performance of the battery.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0009] A method for preparing a high-voltage single-crystal ternary cathode material comprises the following steps:

[0010] S1: Mix the highly active precursor II, lithium source, and flux, and perform a single sintering to obtain product I;

[0011] S2: Mixing product I with a structural stabilizer and performing secondary sintering to obtain product II;

[0012] S3: Mix product II with a surface coating agent and sinter three times to obtain a high-voltage single crystal ternary positive electrode material.

[0013] Furthermore, the D of the highly active precursor II 50 =0.1~5μm, BET≥10m 2 / g.

[0014] Furthermore, the highly active precursor II is obtained by mixing the ternary material precursor I, a solvent, and a dispersant and then ball milling the mixture.

[0015] Furthermore, the ternary material precursor I, solvent, and dispersant are mixed, ball-milled, and then spray-dried to obtain a highly active precursor II.

[0016] Furthermore, the flux includes an electron-deficient compound, and the electron-deficient compound is selected from one or more of boron oxide, boric acid, boron chloride, and boron fluoride.

[0017] Furthermore, the structural stabilizer has anions and cations, the anions are selected from one of phosphate, metaphosphate, and fluoride; and the cations are selected from one or more of Al, Mg, Zr, Ti, Ni, Mn, B, Y, Zn, Mo, Ru, Ta, W, Re, Sn, Ge, or Ga cations.

[0018] Furthermore, the mass ratio of the ternary material precursor I, the dispersant, and the solvent is 1:(0.01~1):(0.5:10).

[0019] Furthermore, the ternary material precursor Ⅰ is Ni x Co y Mnz (OH)2, its D 50 The particle size is 1.0 μm to 50 μm, wherein 0.1≤x≤0.9, 0.1≤y≤0.9, 0.1≤z≤0.9, and x+y+z=1; the dispersant is hexadecyltrimethylammonium chloride and / or dodecyltrimethylammonium bromide; and the solvent is one or more of deionized water, isopropyl alcohol, ethanol, acetone, and the like.

[0020] Furthermore, the mass ratio of the high-activity precursor II to the flux is 1: (0.0001~0.2); the mass ratio of the product I to the structure stabilizer is 1: (0.0001~0.1).

[0021] Furthermore, the primary sintering temperature is 200~850℃, the primary sintering time is 3~15h, and the primary sintering heating rate is 0.5~10℃ / min; after the primary sintering, the material is crushed to obtain product I; the crushing method is one or more of jaw crusher, roller, ball mill, mechanical crushing, air flow crushing, and ball mill.

[0022] Furthermore, the temperature of the secondary sintering is 600~1000℃, the time of the secondary sintering is 5~18h, and the heating rate of the secondary sintering is 0.5~10℃ / min; after the secondary sintering, the material is crushed to obtain product II; the crushing method is one or more of jaw crusher, roller crusher, ball milling, mechanical crushing, air flow crushing, and ball milling.

[0023] Furthermore, the surface coating agent is selected from one or more of oxides, hydroxides, hydroxyl compounds, fluorides, phosphates, acetates, etc. of Al, Mg, Zr, Ti, Ni, Mn, B, Y, Zn, Mo, Ru, Ta, W, Re, Sn, Ge, and Ga.

[0024] Furthermore, the temperature of the three sintering processes is 200-800° C., the time of the three sintering processes is 3-15 hours, and the heating rate of the three sintering processes is 0.5-10° C. / min.

[0025] Furthermore, the product II is mixed with a surface coating agent, sintered three times, and then screened and demagnetized in sequence to obtain a high-voltage single crystal ternary positive electrode material.

[0026] Furthermore, the lithium source is one or more of lithium carbonate, lithium hydroxide, and lithium acetate.

[0027] Furthermore, the lithium ratio Li / Me is (1.0~1.1):1, and Me is the molar sum of the metal elements of the high-activity precursor II.

[0028] The above preparation method produces a high-voltage single-crystal ternary positive electrode material.

[0029] A positive electrode sheet or a lithium-ion battery, comprising the above-mentioned high-voltage single-crystal ternary positive electrode material.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) With the help of flux, the grain boundary fusion energy is reduced, and oriented microcrystalline nuclei can be obtained after one sintering; the oriented microcrystalline nuclei and the structural stabilizer can achieve directional growth of the nuclei after a second sintering; at the same time, the electron-deficient compound can synergistically dope with the electron-rich in the structural stabilizer, which, on the one hand, helps to achieve a more uniform bulk doping of the metal elements in the structural stabilizer, and on the other hand, can better stabilize the crystal structure and inhibit the generation and accumulation of stress.

[0032] (2) The single crystal ternary cathode material prepared according to the preparation method of the present invention has good particle size uniformity, the transition metal elements are distributed more evenly within the grains, and the directional growth of the grains is achieved. The directional growth of the grains has the following benefits: 1) After long cycles, the integrity of the grain structure can be maintained, and the separation of the grain boundaries and the pulverization of the grains can be suppressed; 2) The orderly arrangement of the grains can achieve charge and discharge cycles at high rates; 3) It can suppress lattice distortion and maintain the integrity of the crystal structure. More importantly, the single crystal ternary cathode material prepared by the preparation method of the present invention has a high compaction density. Under high rolling strength, the electrode can maintain the integrity of the coating and avoid grain boundary crushing. The capacity, high and low temperature cycle and rate performance of the material are significantly better than those of traditional single crystal ternary cathode materials.

[0033] (3) By ball-milling the low-activity large-particle ternary material precursor into a high-activity precursor with the assistance of a dispersant and a solvent, the reaction active sites of the precursor and the lithium salt are increased.

[0034] (4) The preparation method of the present invention is simple, the equipment is highly versatile, and it is easy to carry out large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 XRD comparison diagram of the ternary positive electrode materials prepared in Examples 1 and 2 and Comparative Examples 1 and 2;

[0037] Figure 2 SEM images of the ternary cathode materials prepared in Comparative Example 1 and Example 1;

[0038] Figure 3 This is a comparison chart of the cycle performance of the ternary positive electrode materials prepared in comparative examples 1 and 2 and examples 1 and 2 in button batteries at 3.0-4.5V and 45°C. DETAILED DESCRIPTION

[0039] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0040] The present invention provides a method for preparing a high-voltage single-crystal ternary cathode material, which comprises the following steps:

[0041] S1: Mix the highly active precursor II, lithium source, and flux, and perform a single sintering to obtain product I;

[0042] S2: Mixing product I with a structural stabilizer and performing secondary sintering to obtain product II;

[0043] S3: Mix product II with a surface coating agent and sinter three times to obtain a high-voltage single crystal ternary positive electrode material.

[0044] By using flux to reduce the grain boundary fusion energy, oriented microcrystalline nuclei can be obtained after one sintering; the oriented microcrystalline nuclei and structural stabilizers can achieve directional growth of the nuclei after a second sintering.

[0045] The single crystal ternary cathode material prepared according to the preparation method of the present invention has good particle size uniformity, the transition metal elements are more evenly distributed within the grains, and directional growth of the grains is achieved. The directional growth of the grains has the following benefits: 1) After long cycles, the integrity of the grain structure can be maintained, inhibiting the separation of grain boundaries and the pulverization of grains; 2) The orderly arrangement of the grains can achieve charge and discharge cycles at high rates; 3) It can inhibit lattice distortion and maintain the integrity of the crystal structure. More importantly, the single crystal ternary cathode material prepared by the preparation method of the present invention has a high compaction density. Under high rolling strength, the cathode sheet can maintain the integrity of the coating and avoid grain boundary crushing. The material's capacity, high and low temperature cycle and rate performance are significantly better than those of traditional single crystal ternary cathode materials.

[0046] The preparation method of the invention is simple, the equipment has strong versatility, and is easy to carry out large-scale production.

[0047] Preferably, D of the highly active precursor II 50 =0.1~5μm, BET≥10m 2 / g. The highly active precursor II with such D50 value and BET value can increase the reactive sites between the precursor and the lithium salt.

[0048] Preferably, the highly active precursor II is obtained by ball milling the mixture of the ternary material precursor I, a solvent, and a dispersant. By ball milling the low-activity, large-particle ternary material precursor with the aid of a dispersant and a solvent into a highly active precursor, the reactive sites of the precursor with the lithium salt are increased.

[0049] Preferably, the ternary material precursor I, solvent, and dispersant are mixed and then ball-milled, and then spray-dried to obtain the highly active precursor II. Spray drying can rapidly evaporate water and shorten the drying time.

[0050] Preferably, the flux comprises an electron-deficient compound, the electron-deficient compound contains B, and the electron-deficient compound is selected from one or more of boron oxide, boric acid, boron chloride, and boron fluoride.

[0051] Preferably, the structural stabilizer has anions and cations, the anions are selected from one of phosphate, metaphosphate, and fluoride; the cations are selected from one or more of Al, Mg, Zr, Ti, Ni, Mn, B, Y, Zn, Mo, Ru, Ta, W, Re, Sn, Ge or Ga cations; for example, the structural stabilizer can be aluminum phosphate, titanium fluoride, zirconium phosphate, etc.

[0052] The above-mentioned flux has a low melting point, can effectively reduce the grain boundary fusion energy, can promote the formation of microcrystalline nuclei, and the B atoms in the electron-deficient compound can synergistically dope with the electron-rich in the structural stabilizer. On the one hand, it helps to achieve more uniform bulk doping of metal elements in the structural stabilizer, and on the other hand, it can better stabilize the crystal structure and inhibit the generation and accumulation of stress.

[0053] Preferably, the mass ratio of the ternary material precursor I, the dispersant, and the solvent is 1:(0.01~1):(0.5:10), which can be 1:0.05:0.5, 1:0.1:1, 1:1:5, etc. Other point values ​​within the above numerical range can be selected and will not be repeated here.

[0054] Preferably, the ternary material precursor I is Ni x Co y Mn z (OH)2, its D 50 1.0μm~50μm, where 0.1≤x≤0.9, 0.1≤y≤0.9, 0.1≤z≤0.9, and x+y+z=1. For example, the precursor of the ternary material I is D 50 1.0μm Ni 0.5 Co 0.3 Mn 0.2(OH)2、D 50 6.0μm Ni 0.6 Co 0.3 Mn 0.3 (OH)2, etc. Other point values ​​within the above numerical range can be selected and will not be described here one by one.

[0055] Preferably, the dispersant is hexadecyltrimethylammonium chloride and / or dodecyltrimethylammonium bromide; and the solvent is one or more of deionized water, isopropyl alcohol, ethanol, acetone, and the like.

[0056] Preferably, the mass ratio of the high-activity precursor II to the flux is 1:(0.0001~0.2), which can be 1:0.0001, 1:0.01, 1:0.05, 1:0.1, 1:0.2, etc. Other points within the above numerical range can be selected and will not be repeated here.

[0057] Preferably, the mass ratio of product I to the structural stabilizer is 1: (0.0001~0.1), which can be 1:0.0001, 1:0.01, 1:0.05, 1:0.1, etc. Other point values ​​within the above numerical range can be selected and will not be repeated here.

[0058] Preferably, the primary sintering temperature is 200-850°C, the primary sintering time is 3-15h, and the primary sintering heating rate is 0.5-10°C / min. A lower sintering temperature can promote the formation of microcrystalline nuclei. Specifically, the primary sintering temperature can be 200°C, 300°C, 500°C, 700°C, 850°C, etc., and the primary sintering time is 3h, 7h, 9h, 11h, 15h, etc.; the primary sintering heating rate is 0.5°C / min, 1.5°C / min, 5°C / min, 7.5°C / min, 10°C / min, etc. Other point values ​​within the above numerical range can be selected and will not be repeated here.

[0059] Preferably, after the primary sintering, the material is crushed to obtain product I, whose D50 is 1-10 μm; the crushing method is one or more of jaw crusher, roller crusher, ball milling, mechanical crushing, air flow crushing, and ball milling.

[0060] Preferably, the temperature of the secondary sintering is 600-1000°C, the time of the secondary sintering is 5-18h, and the heating rate of the secondary sintering is 0.5-10°C / min; a higher sintering temperature can effectively promote the directional growth of the microcrystalline nucleus. Specifically, the temperature of the secondary sintering can be 600°C, 700°C, 800°C, 900°C, 1000°C, etc.; the time of the secondary sintering is 5h, 7h, 9h, 11h, 14h, 18h, etc.; the heating rate of the secondary sintering is 0.5°C / min, 1.5°C / min, 5°C / min, 7.5°C / min, 10°C / min, etc.; other point values ​​within the above numerical range can be selected and will not be repeated here.

[0061] Preferably, the material after secondary sintering is crushed to obtain product II; the crushing method is one or more of jaw crusher, roller crusher, ball mill, mechanical crushing, air flow crushing, and ball milling.

[0062] Preferably, the surface coating agent is selected from one or more of oxides, hydroxides, hydroxyl compounds, fluorides, phosphates, acetates, etc. of Al, Mg, Zr, Ti, Ni, Mn, B, Y, Zn, Mo, Ru, Ta, W, Re, Sn, Ge, and Ga, such as aluminum oxide, titanium fluoride, zirconium phosphate, etc.

[0063] Preferably, the temperature of the tertiary sintering is 200-800°C, the time of the tertiary sintering is 3-15 hours, and the heating rate of the tertiary sintering is 0.5-10°C / min. The temperature of the tertiary sintering can be 200°C, 300°C, 500°C, 700°C, 800°C, etc.; the time of the secondary sintering is 3 hours, 5 hours, 8 hours, 10 hours, 15 hours, etc.; the heating rate of the secondary sintering is 0.5°C / min, 1.5°C / min, 5°C / min, 7.5°C / min, 10°C / min, etc. Other values ​​within the above numerical range can be selected and will not be repeated here.

[0064] Preferably, Product II is mixed with a surface coating agent, sintered three times, and then sieved and demagnetized to obtain a high-voltage single-crystal ternary cathode material. The addition of the surface coating agent further enhances the electrochemical performance of the cathode material.

[0065] Preferably, the lithium source is one or more of lithium carbonate, lithium hydroxide, and lithium acetate.

[0066] Preferably, the lithium ratio Li / Me is (1.0-1.1):1, and Me is all the metal elements in the high-activity precursor II.

[0067] Example 1

[0068] Preparation of high voltage single crystal ternary cathode material LiNi using boric acid as flux and aluminum phosphate modification 0.6 Co0.1 Mn 0.3 O2, including the following steps:

[0069] (1) 2000g of ternary material precursor Ni with D50=6μm 0.6 Co 0.1 Mn 0.3 (OH)2, 20g hexadecyltrimethylammonium chloride and 2L deionized water were mixed, 2kg zirconium balls were added, and the mixture was ball milled at 800rpm for 6-12h and spray dried to obtain D50=1.0μm, BET=85m 2 / g of highly active precursor II;

[0070] (2) 1000 g of the highly active precursor II prepared in step (1) and 500 g of lithium hydroxide monohydrate were placed in a high-speed mixer, 3.02 g of boric acid was added, and the mixture was mixed at a speed of 1000 r / min for 30 min to obtain a primary mixture; the primary mixture was heated to 600°C at a heating rate of 2°C / min and sintered for 10 h to obtain a primary sintered product, which was then processed by a jaw crusher and a roller mill to obtain product I;

[0071] (3) 1000 g of product I and 3.88 g of aluminum phosphate, a structural stabilizer, were placed in a high-speed mixer and mixed at a speed of 1000 r / min for 30 min to obtain a secondary mixture; the secondary mixture was heated to 920°C at a heating rate of 2°C / min and sintered for 12 h to obtain a secondary sintered material, which was then processed in sequence by a jaw crusher, a roller mill, and a jet mill to obtain product II;

[0072] (4) 500 g of product II and 1.0 g of surface coating agent alumina were put into a high-speed mixer and mixed at a speed of 1000 r / min for 30 min to obtain a tertiary mixture; the tertiary mixture was heated to 600 °C at a heating rate of 5 °C / min and sintered for 6 h, sieved and demagnetized to obtain a high-voltage single crystal ternary positive electrode material.

[0073] Example 2

[0074] Preparation of high voltage single crystal ternary cathode material LiNi using boric acid as flux and zirconium phosphate modification 0.6 Co 0.1 Mn 0.3 O2, including the following steps:

[0075] (1) 2000g of ternary material precursor Ni with D50=6μm 0.6 Co 0.1 Mn 0.3(OH)2, 20g hexadecyltrimethylammonium chloride and 2L deionized water were mixed, 2kg zirconium balls were added, and the mixture was ball milled at 800rpm for 6-12h and spray dried to obtain D50=1.0μm, BET=85m 2 / g of highly active precursor II;

[0076] (2) 1000 g of the highly active precursor II prepared in step (1) and 500 g of lithium hydroxide monohydrate were placed in a high-speed mixer, 3 g of boric acid was added, and the mixture was mixed at a speed of 1000 r / min for 30 min to obtain a primary mixture; the primary mixture was heated to 600°C at a heating rate of 2°C / min and sintered for 10 h to obtain a primary sintered product, which was then processed by a jaw crusher and a roller mill to obtain product I;

[0077] (3) 1000 g of product I and 3.88 g of zirconium phosphate, a structural stabilizer, were placed in a high-speed mixer and mixed at a speed of 1000 r / min for 30 min to obtain a secondary mixture; the secondary mixture was heated to 920°C at a heating rate of 2°C / min and sintered for 12 h to obtain a secondary sintered material, which was then processed in sequence by a jaw crusher, a roller mill, and a jet mill to obtain product II;

[0078] (4) 500 g of product II and 1.0 g of surface coating agent alumina were put into a high-speed mixer and mixed at a speed of 1000 r / min for 30 min to obtain a tertiary mixture; the tertiary mixture was heated to 600 °C at a heating rate of 5 °C / min and sintered for 6 h, sieved and demagnetized to obtain a high-voltage single crystal ternary positive electrode material.

[0079] Example 3

[0080] Preparation of high voltage single crystal ternary cathode material LiNi modified with boron fluoride as flux 0.6 Co 0.1 Mn 0.3 O2, including the following steps:

[0081] (1) 2000g of ternary material precursor Ni with D50=6μm 0.6 Co 0.1 Mn 0.3 (OH)2, 20g hexadecyltrimethylammonium chloride and 2L deionized water were mixed, 2kg zirconium balls were added, and the mixture was ball milled at 800rpm for 6-12h and spray dried to obtain D50=1.0μm, BET=85m 2 / g of highly active precursor II;

[0082] (2) 1000 g of the highly active precursor II prepared in step (1) and 500 g of lithium hydroxide monohydrate were placed in a high-speed mixer, 3.0 g of boron fluoride was added, and the mixture was mixed at a speed of 1000 r / min for 30 min to obtain a primary mixture; the primary mixture was heated to 550° C. at a heating rate of 2° C. / min and sintered for 10 h to obtain a primary sintered product, which was then processed by a jaw crusher and a roller mill to obtain product I;

[0083] (3) 1000 g of product I and 12 g of lanthanum phosphate, a structural stabilizer, were placed in a high-speed mixer and mixed at a speed of 1000 r / min for 30 min to obtain a secondary mixture; the secondary mixture was heated to 920°C at a heating rate of 2°C / min and sintered for 12 h to obtain a secondary sintered material, which was then processed in sequence by a jaw crusher, a roller mill, and a jet mill to obtain product II;

[0084] (4) 500 g of product II and 1.0 g of surface coating agent alumina were put into a high-speed mixer and mixed at a speed of 1000 r / min for 30 min to obtain a tertiary mixture; the tertiary mixture was heated to 600 °C at a heating rate of 5 °C / min and sintered for 6 h, sieved and demagnetized to obtain a high-voltage single crystal ternary positive electrode material.

[0085] Comparative Example 1

[0086] Preparation of ternary cathode material LiNi using traditional method 0.6 Co 0.1 Mn 0.3 O2, including the following steps:

[0087] (1) 1000g of ternary material precursor Ni with D50=6μm 0.6 Co 0.1 Mn 0.3 (OH)2, 500 g of lithium hydroxide monohydrate, and 3.88 g of aluminum oxide were placed in a high-speed mixer and mixed at a speed of 1000 r / min for 30 minutes to obtain a primary mixture; the primary mixture was heated to 920°C at a heating rate of 2°C / min and sintered for 12 hours to obtain a primary sintered material, and the primary sintered material was processed in sequence using a jaw crusher, a double-roll mill, and a jet mill to obtain a primary pulverized material;

[0088] (2) 500 g of the primary crushed material and 1.0 g of alumina as a surface coating agent were put into a high-speed mixer and mixed at a speed of 1000 r / min for 30 min to obtain a secondary mixture; the secondary mixture was heated to 600 °C at a heating rate of 5 °C / min and sintered for 6 h, sieved, and demagnetized to obtain a ternary positive electrode material.

[0089] Comparative Example 2

[0090] Preparation of flux-free ternary cathode material LiNi 0.6 Co 0.1 Mn 0.3 O2, including the following steps:

[0091] (1) 2000g of ternary material precursor Ni with D50=6μm 0.6 Co 0.1 Mn 0.3 (OH)2, 20g hexadecyltrimethylammonium chloride and 2L deionized water were mixed, 2kg zirconium balls were added, and the mixture was ball milled at 800rpm for 6-12h and spray dried to obtain D50=1.0μm, BET=85m 2 / g of highly active precursor II;

[0092] (2) 1000 g of the highly active precursor II prepared in step (1) and 500 g of lithium hydroxide monohydrate were placed in a high-speed mixer and mixed at a speed of 1000 r / min for 30 min to obtain a primary mixture; the primary mixture was heated to 600° C. at a heating rate of 2° C. / min and sintered for 10 h to obtain a primary sintered product; the primary sintered product was processed in sequence with a jaw crusher and a roller mill to obtain a primary crushed product;

[0093] (3) 1000 g of product I and 3.88 g of aluminum phosphate, a structural stabilizer, were placed in a high-speed mixer and mixed at a speed of 1000 r / min for 30 min to obtain a secondary mixture; the secondary mixture was heated to 920°C at a heating rate of 2°C / min and sintered for 12 h to obtain a secondary sintered product; the secondary sintered product was processed in sequence by a jaw crusher, a roller mill, and a jet mill to obtain a secondary crushed product;

[0094] (4) 500 g of the secondary crushed material and 1.0 g of alumina as a surface coating agent were put into a high-speed mixer and mixed at a speed of 1000 r / min for 30 min to obtain a secondary mixture; the secondary mixture was heated to 600 °C at a heating rate of 5 °C / min and sintered for 6 h, sieved, and demagnetized to obtain a ternary positive electrode material.

[0095] Comparative Example 3

[0096] Preparation of ternary cathode material LiNi without flux assistance and structural stabilizer modification 0.6 Co 0.1 Mn 0.3 O2, including the following steps:

[0097] (1) 2000g of ternary material precursor Ni with D50=6μm 0.6 Co 0.1 Mn 0.3(OH)2, 20g hexadecyltrimethylammonium chloride and 2L deionized water were mixed, 2kg zirconium balls were added, and the mixture was ball milled at 800rpm for 6-12h and spray dried to obtain D50=1.0μm, BET=85m 2 / g of highly active precursor II;

[0098] (2) 1000 g of the highly active precursor II prepared in step (1) and 500 g of lithium hydroxide monohydrate were placed in a high-speed mixer, 3.02 g of titanium oxide was added, and the mixture was mixed at a speed of 1000 r / min for 30 min to obtain a primary mixture; the primary mixture was heated to 600°C at a heating rate of 2°C / min and sintered for 10 h to obtain a primary sintered product, and the primary sintered product was processed in sequence by a jaw crusher and a roller mill to obtain a primary crushed product;

[0099] (3) 1000 g of the primary crushed material and 3.88 g of magnesium oxide were placed in a high-speed mixer and mixed at a speed of 1000 r / min for 30 min to obtain a secondary mixture; the secondary mixture was heated to 920°C at a heating rate of 2°C / min and sintered for 12 h to obtain a secondary sintered material, which was then processed in sequence by a jaw crusher, a roller mill, and a jet mill to obtain a secondary crushed material;

[0100] (4) 500 g of the secondary crushed material and 1.0 g of alumina as a surface coating agent were put into a high-speed mixer and mixed at a speed of 1000 r / min for 30 min to obtain a tertiary mixture; the tertiary mixture was heated to 600 °C at a heating rate of 5 °C / min and sintered for 6 h, sieved, and demagnetized to obtain a ternary positive electrode material.

[0101] Comparative Example 4

[0102] Preparation of LiNi ternary cathode material without structural stabilizer modification 0.6 Co 0.1 Mn 0.3 O2, including the following steps:

[0103] (1) 2000g of ternary material precursor Ni with D50=6μm 0.6 Co 0.1 Mn 0.3 (OH)2, 20g hexadecyltrimethylammonium chloride and 2L deionized water were mixed, 2kg zirconium balls were added, and the mixture was ball milled at 800rpm for 6-12h and spray dried to obtain D50=1.0μm, BET=85m 2 / g of highly active precursor II;

[0104] (2) 1000 g of the highly active precursor II prepared in step (1) and 500 g of lithium hydroxide monohydrate were placed in a high-speed mixer, 3.02 g of boric acid was added, and the mixture was mixed at a speed of 1000 r / min for 30 min to obtain a primary mixture; the primary mixture was heated to 600°C at a heating rate of 2°C / min and sintered for 10 h to obtain a primary sintered product, and the primary sintered product was processed in sequence by a jaw crusher and a roller mill to obtain a primary crushed product;

[0105] (3) 1000 g of the primary crushed material was heated to 920°C at a heating rate of 2°C / min and sintered for 12 h to obtain a secondary sintered material. The secondary sintered material was processed in sequence by a jaw crusher, a roller mill, and a jet mill to obtain a secondary crushed material;

[0106] (4) 500 g of the secondary crushed material and 1.0 g of alumina as a surface coating agent were put into a high-speed mixer and mixed at a speed of 1000 r / min for 30 min to obtain a tertiary mixture; the tertiary mixture was heated to 600 °C at a heating rate of 5 °C / min and sintered for 6 h, sieved, and demagnetized to obtain a ternary positive electrode material.

[0107] XRD test was performed on the ternary cathode materials prepared in Comparative Examples 2 and 4 and Examples 1 and 2, and the results were as follows: Figure 1 As can be seen from the XRD patterns, no impurity peaks appear in the ternary cathode materials prepared in Comparative Examples 2 and 4 and Examples 1 and 2, indicating that the flux-assisted and structural stabilizer-modified materials have not changed the crystal structure of the materials. Table 1 shows the main unit cell parameters of Comparative Examples 1-4 and Examples 1-3. A comparison of the data in Table 1 shows that the intensity ratio of the 003 / 104 peak of Examples 1-3 is significantly better than that of Comparative Examples 1-4, indicating that the ternary cathode materials of Examples 1-3 have better crystal integrity, less Li / Ni mixing, more effective positive ion arrangement, and better structural stability of the materials, which is conducive to the performance of cycling performance.

[0108] Table 1 Comparison of main unit cell parameters between comparative examples 1 to 4 and examples 1 to 3

[0109]

[0110] The high voltage single crystal cathode material prepared in Example 1 was scanned by SEM and compared with the SEM of Comparative Example 2. Figure 2 As shown in the SEM image, it can be seen that the ternary cathode material of Example 1 has good dispersibility, a high roundness of the primary grain surface, and no fine powder; while the ternary cathode material of Comparative Example 2 has more angular primary grain surfaces, and due to the irregular shape of the primary grains, stress anisotropy is easily generated during the electrode sheet rolling, causing particle cracking and deterioration of cycle performance and high-temperature performance. The better morphology of Example 1 is due to the flux significantly reducing the fusion energy of the grain boundaries, which helps to form a more rounded morphology.

[0111] The cycle performance of the ternary cathode materials prepared in Comparative Examples 2 and 4 and Examples 1 and 2 at 45°C was tested. Figure 3 .from Figure 3 It can be seen that under the same conditions, the capacity retention rate of the positive electrode materials prepared in Examples 1 and 2 is higher than that of the positive electrode materials prepared in Comparative Examples 2 and 4.

[0112] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a high voltage single crystal ternary cathode material, characterized in that: It includes the following steps: S1: mixing a highly active precursor II, a lithium source, and a flux, and performing a single sintering to obtain a product I; the flux comprises an electron-deficient compound, and the electron-deficient compound is selected from one or more of boron oxide, boric acid, boron chloride, and boron fluoride; S2: mixing product I with a structural stabilizer and performing secondary sintering to obtain product II; the structural stabilizer has anions and cations, the anions are selected from one of phosphate, metaphosphate, and fluoride; the cations are selected from one or more of Al, Mg, Zr, Ti, Ni, Mn, B, Y, Zn, Mo, Ru, Ta, W, Re, Sn, Ge, or Ga cations; S3: Mixing product II with a surface coating agent and sintering three times to obtain a high-voltage single crystal ternary cathode material; The high-activity precursor II is obtained by mixing the ternary material precursor I, a solvent, and a dispersant and then ball milling.

2. The method for preparing a high voltage single crystal ternary cathode material according to claim 1, wherein: The D50 of the highly active precursor II is 0.1~5μm, and BET is ≥10m 2 / g.

3. The method for preparing a high voltage single crystal ternary cathode material according to claim 1, wherein: The mass ratio of ternary material precursor I, dispersant, and solvent is 1:(0.01~1):(0.5~10).

4. The method for preparing a high voltage single crystal ternary cathode material according to claim 2, wherein: At least one of the following conditions is met: the ternary material precursor I is Ni x Co y Mn z (OH)2, its D 50 The particle size is 1.0 μm to 50 μm, wherein 0.1≤x≤0.9, 0.1≤y≤0.9, 0.1≤z≤0.9, and x+y+z=1; the dispersant is hexadecyltrimethylammonium chloride and / or dodecyltrimethylammonium bromide; and the solvent is one or more of deionized water, isopropyl alcohol, ethanol, and acetone.

5. The method for preparing a high voltage single crystal ternary cathode material according to claim 1, wherein: The mass ratio of the high-activity precursor II to the flux is 1: (0.0001~0.2); the mass ratio of the product I to the structure stabilizer is 1: (0.0001~0.1).

6. The method for preparing a high voltage single crystal ternary cathode material according to claim 1, wherein: The primary sintering temperature is 200-850°C, the primary sintering time is 3-15h, and the primary sintering heating rate is 0.5-10°C / min.

7. The method for preparing a high voltage single crystal ternary cathode material according to claim 1, wherein: The temperature of the secondary sintering is 600-1000°C, the time of the secondary sintering is 5-18h, and the heating rate of the secondary sintering is 0.5-10°C / min.

8. The method for preparing a high voltage single crystal ternary cathode material according to claim 1, wherein: The surface coating agent is selected from one or more of oxides, hydroxides, hydroxyl compounds, fluorides, phosphates, and acetates of Al, Mg, Zr, Ti, Ni, Mn, B, Y, Zn, Mo, Ru, Ta, W, Re, Sn, Ge, and Ga.

9. The method for preparing a high voltage single crystal ternary cathode material according to claim 1, wherein: The temperature of the three sintering processes is 200-800°C, the time of the three sintering processes is 3-15h, and the heating rate of the three sintering processes is 0.5-10°C / min.

10. A high voltage single crystal ternary cathode material, characterized in that: The high-voltage single-crystal ternary cathode material is prepared by the method for preparing the high-voltage single-crystal ternary cathode material according to any one of claims 1 to 9.

11. A positive electrode sheet, characterized in that: It includes the high-voltage single-crystal ternary positive electrode material as claimed in claim 10.

12. A lithium ion battery, characterized in that: It includes the positive electrode sheet according to claim 11.

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