Modified high-nickel ternary positive electrode material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of battery materials, and particularly relates to a modified high-nickel ternary positive electrode material and a preparation method and application thereof. The preparation method of the modified high-nickel ternary positive electrode material provided by the invention comprises the following steps: 1) mixing a lithium source, a precursor, a tellurium source and a divalent metal compound, and performing first calcination to obtain a first calcined product; (2) dissolving tellurate in an organic solvent, mixing and grinding the formed tellurate organic solvent solution and the first burning product obtained in the step (1), and then carrying out second burning to obtain a second burning product; the tellurate is selected from at least one of potassium tellurite and sodium tellurite; and (3) washing the secondary calcined product obtained in the step (2) with water, mixing with boric acid, and carrying out third calcination to obtain the modified high-nickel ternary positive electrode material. Through the specific preparation method and the synergistic effect among the steps, the obtained modified high-nickel ternary positive electrode material has good specific capacity, first effect and cycle performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery materials, and in particular relates to a modified high-nickel ternary positive electrode material and a preparation method and application thereof. Background Art

[0002] Existing high-nickel layered oxide positive electrode materials (high-nickel ternary positive electrode materials) have a high theoretical specific capacity and are considered to be the most promising next-generation positive electrode materials for high-energy-density lithium-ion batteries. However, due to the reduction in manganese and cobalt content, the existing high-nickel layered oxide positive electrode materials are more prone to irreversible mechanical damage, poor chemical stability during storage or use, and capacity decay. At the same time, as the nickel content increases, the high-nickel layered oxide positive electrode material easily reacts with water and CO2 in the air to generate LiOH and Li2CO3, which will result in high residual alkali on the surface. These reasons all lead to poor specific capacity, first efficiency and cycle performance of high-nickel layered oxide positive electrode materials.

[0003] Existing modification methods include bulk doping to improve the structural stability of high-nickel layered oxide cathode materials, surface coating to inhibit surface side reactions, and preparation of gradient materials and single crystals to improve stress-strain stability. However, the existing modification methods still have limited effect on improving the specific capacity, first efficiency and cycle performance of high-nickel layered oxide cathode materials. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect that the improvement effect of specific capacity, first efficiency and cycle performance of existing high-nickel layered oxide positive electrode materials is still limited, thereby providing a modified high-nickel ternary positive electrode material and its preparation method and application.

[0005] The present invention provides a method for preparing a modified high-nickel ternary positive electrode material, comprising the following steps:

[0006] 1) mixing a lithium source, a precursor, a tellurium source and a divalent metal compound, and performing a first calcination to obtain a calcined product;

[0007] 2) dissolving the tellurate in an organic solvent, mixing the formed tellurate organic solvent solution with the first sintered product obtained in step 1), grinding the mixture, and then subjecting the mixture to a second calcination to obtain a second sintered product;

[0008] The tellurite is selected from at least one of potassium tellurite and sodium tellurite;

[0009] 3) The second calcined product obtained in step 2) is washed with water and mixed with boric acid, and subjected to a third calcination to obtain the modified high-nickel ternary positive electrode material.

[0010] Preferably, the divalent metal compound in step 1) is at least one selected from cobaltous hydroxide, strontium carbonate, magnesium oxide, and calcium oxide;

[0011] The tellurite is potassium tellurite and sodium tellurite;

[0012] Optionally, the mass ratio of potassium tellurite to sodium tellurite is (0.1-1): (0.1-1);

[0013] The molar amount of nickel in the precursor accounts for more than 90% of the total molar amount of metal elements in the precursor;

[0014] The lithium source is selected from at least one of lithium hydroxide and lithium carbonate;

[0015] The tellurium source in step 1) is selected from tellurium dioxide.

[0016] Preferably, the chemical formula of the precursor in step 1) is Ni x Co y Mn z O2, and 0.9≤x≤0.99, 0.01≤y≤0.09, 0.01≤z≤0.09, x+y+z=1;

[0017] In step 1), the ratio of the total molar amount of metal elements in the precursor, the molar amount of tellurium elements in the tellurium source, and the molar amount of divalent metal elements in the divalent metal compound is (0.975-1): (0.0001-0.015): (0.0001-0.01);

[0018] It can be understood that the total molar amount of metal elements in the precursor is expressed in the general formula Ni x Co y Mn z Taking O2 as an example, it includes the sum of the molar amounts of the metal element nickel, the molar amount of the metal element cobalt and the molar amount of the metal element manganese.

[0019] In step 1), the sum of the total molar amount of metal elements in the precursor, the molar amount of tellurium elements in the tellurium source and the molar amount of divalent metal elements in the divalent metal compound is recorded as a, and the molar amount of lithium elements in the lithium source is recorded as b, and b:a is (1.01-1.06):1.

[0020] Preferably, in step 1), the first calcination temperature is 700-850° C., and the first calcination time is 8-16 h;

[0021] The calcination atmosphere of the first calcination in step 1) includes an oxygen-containing atmosphere.

[0022] Optionally, the oxygen-containing atmosphere includes at least one of an oxygen atmosphere and an air atmosphere;

[0023] Optionally, after the first calcination step, the steps of crushing and screening are also included.

[0024] Preferably, the organic solvent in step 2) is selected from ethanol;

[0025] In step 2), the tellurate is dissolved in an organic solvent, and the mass concentration of the tellurium element in the formed tellurate organic solvent solution is 0.01-0.1wt%;

[0026] The mass ratio of the tellurite organic solvent solution in step 2) to the sintered product obtained in step 1) is (1-2):2;

[0027] Preferably, the grinding speed is 300-600 rpm, and the grinding time is 0.5-1 h;

[0028] Optionally, the grinding comprises ball milling;

[0029] The second calcination temperature is 500-700°C, and the second calcination time is 6-12h;

[0030] The second calcining atmosphere comprises an oxygen-containing atmosphere;

[0031] Optionally, the oxygen-containing atmosphere includes at least one of an oxygen atmosphere and an air atmosphere.

[0032] Preferably, the second calcined product in step 3) is mixed with water and washed, and then dried after washing to obtain a washed second calcined product, which is then mixed with boric acid and calcined for the third time to obtain the modified high-nickel ternary positive electrode material;

[0033] Preferably, the mass ratio of the second burning product to water is 1:(0.5-1.0);

[0034] The mass ratio of the washed second calcined product to boric acid is 700:(2-10);

[0035] The third calcination temperature is 200-400° C., and the third calcination time is 5-11 hours.

[0036] The present invention provides a modified high-nickel ternary positive electrode material, which is prepared by the above-mentioned preparation method of the modified high-nickel ternary positive electrode material.

[0037] The present invention also provides an application of the modified high-nickel ternary positive electrode material described above in a lithium-ion battery.

[0038] The technical solution of the present invention has the following advantages:

[0039] 1. The preparation method of the modified high-nickel ternary positive electrode material provided by the present invention comprises the following steps: 1) mixing a lithium source, a precursor, a tellurium source and a divalent metal compound, and obtaining a first calcined product after a first calcination; 2) dissolving a tellurate in an organic solvent, and mixing and grinding the formed tellurate organic solvent solution with the first calcined product obtained in step 1), and then subjecting the mixture to a second calcination to obtain a second calcined product; the tellurate is selected from at least one of potassium tellurite and sodium tellurite; 3) washing the second calcined product obtained in step 2) with water, mixing it with boric acid, and subjecting the mixture to a third calcination to obtain the modified high-nickel ternary positive electrode material. The present invention forms a Te-Ni-Ni-Te ordered superstructure on the positive electrode material as a whole by doping a tellurium source in the bulk phase, refining the grains, and then wet-coating the surface with potassium tellurite and / or sodium tellurite, thereby inhibiting thermodynamically irreversible phase change and improving the stability of the material, thereby improving the specific capacity, first efficiency and cycle performance of the positive electrode material. At the same time, by introducing low-valent elements through divalent metal compounds during the first calcination, the lithium-nickel mixing caused by the introduction of tellurium is reduced, and the electrochemical performance of the positive electrode material is further improved in coordination with the tellurium source; by wet-coating potassium tellurite and / or sodium tellurite, not only the tellurium element (including the formed nano lithium tellurite), sodium element and / or Or the surface coating of potassium elements, and also promote the shallow surface doping of sodium ions and / or potassium ions at the interface of the coating layer and the positive electrode material by wet coating. After the sodium ions and potassium ions penetrate into the shallow surface layer, they occupy part of the lithium ion position. The ion radius of the sodium ions and potassium ions is larger than the radius of the lithium ions, which will increase the interlayer spacing of the positive electrode material, improve the efficiency of lithium ions passing through, and thus improve the specific capacity, first effect and cycle performance of the positive electrode material; the coating layer formed by wet coating is uniform and flat, effectively isolates the electrolyte, avoids the influence of the electrolyte on the positive electrode material, significantly improves the structural stability of the positive electrode material, and thus improves the first effect and cycle performance of the positive electrode material. The present invention uses a specific preparation method and the synergy between the various steps to obtain a modified high-nickel ternary positive electrode material with good specific capacity, first effect and cycle performance.

[0040] 2. The preparation method of the modified high-nickel ternary positive electrode material provided by the present invention, preferably the tellurite is potassium tellurite and sodium tellurite; the present invention realizes the doping of sodium ions and potassium ions in the surface layer by simultaneously wet coating potassium tellurite and sodium tellurite, occupying the lithium ion position, and at the same time, the radius of sodium ions is smaller than the radius of potassium ions, but both are larger than the radius of lithium ions, and the doping of potassium ions and sodium ions in the surface layer synergistically increases the interlayer spacing of the crystal, produces abundant lattice defects, broadens the transmission path of Li, and improves the diffusion coefficient of Li. At the same time, lithium tellurate is formed in situ on the surface to promote the transmission and migration of lithium ions and then electrons; the coating effect of nano lithium tellurate is also conducive to promoting the interface stability of the electrode material and the electrolyte, and reducing the corrosion of the electrolyte to the active material. The synergistic coating of potassium tellurite and sodium tellurite further enhances the structural stability of the positive electrode material, and the modified high-nickel ternary positive electrode material obtained has higher specific capacity, first effect and cycle performance. DETAILED DESCRIPTION

[0041] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0042] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0043] Example 1

[0044] This embodiment provides a method for preparing a modified high-nickel ternary positive electrode material, comprising the following steps:

[0045] 1) Ni 0.92 Co 0.05 Mn 0.03 The (OH)2 ternary precursor, lithium hydroxide, tellurium dioxide and cobaltous hydroxide are prepared according to Ni 0.92 Co 0.05 Mn 0.03 The total molar amount of nickel, cobalt and manganese in the (OH)2 ternary precursor, the molar amount of lithium in lithium hydroxide, the molar amount of tellurium in tellurium dioxide and the molar amount of cobalt in cobaltous hydroxide are mixed in a high-speed mixer in a ratio of 1.04:0.999:0.0008:0.0002, placed in a muffle furnace, calcined at 780°C for 10 hours in an oxygen atmosphere, crushed and sieved to obtain a calcined product;

[0046] 2) potassium tellurite is dissolved in ethanol to form a potassium tellurite ethanol solution with a tellurium element mass concentration of 0.05 wt%, the formed potassium tellurite ethanol solution is then mixed with the first sintered product obtained in step 1) at a mass ratio of 1:2, placed in a ball mill, ball milled at a speed of 400 rpm for 0.5 h, then dried, and then calcined at 650° C. in an oxygen atmosphere for 10 h to obtain a second sintered product;

[0047] 3) The second calcined product obtained in step 2) was mixed with water in a mass ratio of 1:0.5 and washed, and then dried to obtain a washed second calcined product, and then 700 g of the washed second calcined product was mixed with 4 g of boric acid by a high-speed mixer, and calcined at 300 ° C for 6 h to obtain the modified high-nickel ternary positive electrode material.

[0048] Example 2

[0049] This embodiment provides a method for preparing a modified high-nickel ternary positive electrode material, comprising the following steps:

[0050] 1) Ni 0.92 Co 0.05 Mn 0.03 The (OH)2 ternary precursor, lithium hydroxide, tellurium dioxide and cobaltous hydroxide are prepared according to Ni 0.92 Co 0.05 Mn 0.03 The total molar amount of nickel, cobalt and manganese in the (OH)2 ternary precursor, the molar amount of lithium in lithium hydroxide, the molar amount of tellurium in tellurium dioxide and the molar amount of cobalt in cobaltous hydroxide are mixed in a high-speed mixer in a ratio of 1.04:0.999:0.0008:0.0002, placed in a muffle furnace, calcined at 780°C for 10 hours in an oxygen atmosphere, crushed and sieved to obtain a calcined product;

[0051] 2) potassium tellurite is dissolved in ethanol to form a potassium tellurite ethanol solution with a tellurium element mass concentration of 0.01 wt%, the formed potassium tellurite ethanol solution is then mixed with the first sintered product obtained in step 1) at a mass ratio of 1.5:2, placed in a ball mill, ball milled at a speed of 400 rpm for 0.5 h, then dried, and then calcined at 650° C. in an oxygen atmosphere for 10 h to obtain a second sintered product;

[0052] 3) The second calcined product obtained in step 2) was mixed with water in a mass ratio of 1:0.5 and washed, and then dried to obtain a washed second calcined product, and then 700 g of the washed second calcined product was mixed with 4 g of boric acid by a high-speed mixer, and calcined at 300 ° C for 6 h to obtain the modified high-nickel ternary positive electrode material.

[0053] Example 3

[0054] This embodiment provides a method for preparing a modified high-nickel ternary positive electrode material, comprising the following steps:

[0055] 1) Ni 0.92 Co 0.05 Mn 0.03 The (OH)2 ternary precursor, lithium hydroxide, tellurium dioxide and cobaltous hydroxide are prepared according to Ni 0.92 Co 0.05 Mn 0.03 The total molar amount of nickel, cobalt and manganese in the (OH)2 ternary precursor, the molar amount of lithium in lithium hydroxide, the molar amount of tellurium in tellurium dioxide and the molar amount of cobalt in cobaltous hydroxide are mixed in a high-speed mixer in a ratio of 1.04:0.999:0.0008:0.0002, placed in a muffle furnace, calcined at 780°C for 10 hours in an oxygen atmosphere, crushed and sieved to obtain a calcined product;

[0056] 2) dissolving sodium tellurite in ethanol to form a sodium tellurite ethanol solution with a tellurium element mass concentration of 0.05 wt%, and mixing the formed sodium tellurite ethanol solution with the first sintered product obtained in step 1) at a mass ratio of 1:2, placing in a ball mill, ball milling at a speed of 400 rpm for 0.5 h, and then drying, and then calcining at 650° C. in an oxygen atmosphere for 10 h to obtain a second sintered product;

[0057] 3) The second calcined product obtained in step 2) was mixed with water in a mass ratio of 1:0.5 and washed, and then dried to obtain a washed second calcined product, and then 700 g of the washed second calcined product was mixed with 4 g of boric acid by a high-speed mixer, and calcined at 300 ° C for 6 h to obtain the modified high-nickel ternary positive electrode material.

[0058] Example 4

[0059] This embodiment provides a method for preparing a modified high-nickel ternary positive electrode material, comprising the following steps:

[0060] 1) Ni 0.92 Co 0.05 Mn 0.03 The (OH)2 ternary precursor, lithium hydroxide, tellurium dioxide and cobaltous hydroxide are prepared according to Ni 0.92 Co 0.05 Mn 0.03 The total molar amount of nickel, cobalt and manganese in the (OH)2 ternary precursor, the molar amount of lithium in lithium hydroxide, the molar amount of tellurium in tellurium dioxide and the molar amount of cobalt in cobaltous hydroxide are mixed in a high-speed mixer in a ratio of 1.04:0.999:0.0008:0.0002, placed in a muffle furnace, calcined at 780°C for 10 hours in an oxygen atmosphere, crushed and sieved to obtain a calcined product;

[0061] 2) dissolving potassium tellurite in ethanol to form a potassium tellurite ethanol solution with a tellurium element mass concentration of 0.05wt%, dissolving sodium tellurite in ethanol to form a sodium tellurite ethanol solution with a tellurium element mass concentration of 0.05wt%, and mixing the potassium tellurite ethanol solution and the sodium tellurite ethanol solution with the first sintered product obtained in step 1) in a mass ratio of 0.5:0.5:2, placing in a ball mill, ball milling at a speed of 400rpm for 0.5h, then drying, and then calcining at 650°C in an oxygen atmosphere for 10h to obtain a second sintered product;

[0062] 3) The second calcined product obtained in step 2) was mixed with water in a mass ratio of 1:0.5 and washed, and then dried to obtain a washed second calcined product, and then 700 g of the washed second calcined product was mixed with 4 g of boric acid by a high-speed mixer, and calcined at 300 ° C for 6 h to obtain the modified high-nickel ternary positive electrode material.

[0063] Example 5

[0064] This embodiment provides a method for preparing a modified high-nickel ternary positive electrode material, comprising the following steps:

[0065] 1) Ni 0.92 Co 0.05 Mn 0.03 The (OH)2 ternary precursor, lithium hydroxide, tellurium dioxide and cobaltous hydroxide are prepared according to Ni 0.92 Co 0.05 Mn 0.03 The total molar amount of nickel, cobalt and manganese in the (OH)2 ternary precursor, the molar amount of lithium in lithium hydroxide, the molar amount of tellurium in tellurium dioxide and the molar amount of cobalt in cobaltous hydroxide are mixed in a high-speed mixer in a ratio of 1.04:0.999:0.0008:0.0002, placed in a muffle furnace, calcined at 850°C for 8h in an oxygen atmosphere, crushed and sieved to obtain a calcined product;

[0066] 2) potassium tellurite is dissolved in ethanol to form a potassium tellurite ethanol solution with a tellurium element mass concentration of 0.03 wt%, the formed potassium tellurite ethanol solution is then mixed with the first sintered product obtained in step 1) at a mass ratio of 1.8:2, placed in a ball mill, ball milled at a speed of 400 rpm for 0.5 h, then dried, and then calcined at 500° C. in an oxygen atmosphere for 12 h to obtain a second sintered product;

[0067] 3) The second calcined product obtained in step 2) was mixed with water in a mass ratio of 1:0.5 and washed, and then dried to obtain a washed second calcined product, and then 700 g of the washed second calcined product was mixed with 3 g of boric acid by a high-speed mixer, and calcined at 200 ° C for 10 h to obtain the modified high-nickel ternary positive electrode material.

[0068] Example 6

[0069] This embodiment provides a method for preparing a modified high-nickel ternary positive electrode material, comprising the following steps:

[0070] 1) Ni 0.92 Co 0.05 Mn 0.03 (OH)2 ternary precursor, lithium carbonate, tellurium dioxide and cobalt hydroxide were prepared according to Ni 0.92 Co 0.05 Mn 0.03 The total molar amount of nickel, cobalt and manganese in the (OH)2 ternary precursor, the molar amount of lithium in lithium carbonate, the molar amount of tellurium in tellurium dioxide and the molar amount of cobalt in cobaltous hydroxide are mixed in a high-speed mixer in a ratio of 1.04:0.998:0.001:0.001, placed in a muffle furnace, calcined at 700°C for 16 hours in an oxygen atmosphere, and crushed and sieved to obtain a calcined product;

[0071] 2) potassium tellurite is dissolved in ethanol to form a potassium tellurite ethanol solution with a tellurium element mass concentration of 0.1 wt%, the formed potassium tellurite ethanol solution is then mixed with the first sintered product obtained in step 1) at a mass ratio of 1:2, placed in a ball mill, ball milled at a speed of 400 rpm for 0.5 h, then dried, and then calcined at 700° C. in an oxygen atmosphere for 6 h to obtain a second sintered product;

[0072] 3) The second calcined product obtained in step 2) was mixed with water in a mass ratio of 1:1.0 and washed, and then dried to obtain a washed second calcined product, and then 700 g of the washed second calcined product was mixed with 5 g of boric acid by a high-speed mixer, and calcined at 400 ° C for 6 h to obtain the modified high-nickel ternary positive electrode material.

[0073] Comparative Example 1

[0074] This comparative example provides a method for preparing a modified high-nickel ternary positive electrode material, comprising the following steps:

[0075] 1) Ni 0.92 Co 0.05 Mn 0.03 The (OH)2 ternary precursor, lithium hydroxide, tellurium dioxide and cobaltous hydroxide are prepared according to Ni 0.92 Co 0.05 Mn 0.03 The total molar amount of nickel, cobalt and manganese in the (OH)2 ternary precursor, the molar amount of lithium in lithium hydroxide, the molar amount of tellurium in tellurium dioxide and the molar amount of cobalt in cobaltous hydroxide are mixed in a high-speed mixer in a ratio of 1.04:0.999:0.0008:0.0002, placed in a muffle furnace, calcined at 780°C for 10 hours in an oxygen atmosphere, crushed and sieved to obtain a calcined product;

[0076] 2) dissolving telluric acid in ethanol to form a telluric acid ethanol solution with a tellurium element mass concentration of 0.05 wt%, and mixing the formed telluric acid ethanol solution with the first sintered product obtained in step 1) at a mass ratio of 1:2, placing in a ball mill, ball milling at a speed of 400 rpm for 0.5 h, and then drying, and then calcining at 650° C. in an oxygen atmosphere for 10 h to obtain a second sintered product;

[0077] 3) The second calcined product obtained in step 2) was mixed with water in a mass ratio of 1:0.5 and washed, and then dried to obtain a washed second calcined product, and then 700 g of the washed second calcined product was mixed with 4 g of boric acid by a high-speed mixer, and calcined at 300 ° C for 6 h to obtain the modified high-nickel ternary positive electrode material.

[0078] Comparative Example 2

[0079] This comparative example provides a method for preparing a modified high-nickel ternary positive electrode material, comprising the following steps:

[0080] 1) Ni 0.92 Co 0.05 Mn 0.03 The (OH)2 ternary precursor, lithium hydroxide, tellurium dioxide and cobaltous hydroxide are prepared according to Ni 0.92 Co 0.05 Mn 0.03 The total molar amount of nickel, cobalt and manganese in the (OH)2 ternary precursor, the molar amount of lithium in lithium hydroxide, the molar amount of tellurium in tellurium dioxide and the molar amount of cobalt in cobaltous hydroxide are mixed in a high-speed mixer in a ratio of 1.04:0.999:0.0008:0.0002, placed in a muffle furnace, calcined at 780°C for 10 hours in an oxygen atmosphere, crushed and sieved to obtain a calcined product;

[0081] 2) placing the first calcined product obtained in step 1) in a ball mill, ball milling at 400 rpm for 0.5 h, and then calcining at 650° C. in an oxygen atmosphere for 10 h to obtain a second calcined product;

[0082] 3) The second calcined product obtained in step 2) was mixed with water in a mass ratio of 1:0.5 and washed, and then dried to obtain a washed second calcined product, and then 700 g of the washed second calcined product was mixed with 4 g of boric acid by a high-speed mixer, and calcined at 300 ° C for 6 h to obtain the modified high-nickel ternary positive electrode material.

[0083] Comparative Example 3

[0084] This comparative example provides a method for preparing a modified high-nickel ternary positive electrode material, comprising the following steps:

[0085] 1) Ni 0.92 Co 0.05 Mn 0.03 The (OH)2 ternary precursor, lithium hydroxide, tellurium dioxide and cobaltous hydroxide are prepared according to Ni 0.92 Co 0.05 Mn 0.03 The total molar amount of nickel, cobalt and manganese in the (OH)2 ternary precursor, the molar amount of lithium in lithium hydroxide, the molar amount of tellurium in tellurium dioxide and the molar amount of cobalt in cobaltous hydroxide are mixed in a high-speed mixer in a ratio of 1.04:0.999:0.0008:0.0002, placed in a muffle furnace, calcined at 780°C for 10 hours in an oxygen atmosphere, crushed and sieved to obtain a calcined product;

[0086] 2) Mixing potassium tellurite with the first calcined product obtained in step 1), placing in a ball mill, and ball milling at a speed of 400 rpm for 0.5 h, wherein the mass ratio of the tellurium element in the potassium tellurite to the first calcined product is 0.05:2, and then calcining at 650° C. in an oxygen atmosphere for 10 h to obtain a second calcined product;

[0087] 3) The second calcined product obtained in step 2) was mixed with water in a mass ratio of 1:0.5 and washed, and then dried to obtain a washed second calcined product, and then 700 g of the washed second calcined product was mixed with 4 g of boric acid by a high-speed mixer, and calcined at 300 ° C for 6 h to obtain the modified high-nickel ternary positive electrode material.

[0088] Comparative Example 4

[0089] This comparative example provides a method for preparing a modified high-nickel ternary positive electrode material, comprising the following steps:

[0090] 1) Ni 0.92 Co 0.05 Mn 0.03 (OH)2 ternary precursor, lithium hydroxide and tellurium dioxide are prepared according to Ni 0.92 Co 0.05 Mn 0.03 The total molar amount of nickel, cobalt and manganese in the (OH)2 ternary precursor, the molar amount of lithium in lithium hydroxide and the molar amount of tellurium in tellurium dioxide are mixed in a high-speed mixer at a ratio of 1.04:0.999:0.001, placed in a muffle furnace, calcined at 780°C for 10 hours in an oxygen atmosphere, and crushed and sieved to obtain a calcined product;

[0091] 2) potassium tellurite is dissolved in ethanol to form a potassium tellurite ethanol solution with a tellurium element mass concentration of 0.05 wt%, the formed potassium tellurite ethanol solution is then mixed with the first sintered product obtained in step 1) at a mass ratio of 1:2, placed in a ball mill, ball milled at a speed of 400 rpm for 0.5 h, then dried, and then calcined at 650° C. in an oxygen atmosphere for 10 h to obtain a second sintered product;

[0092] 3) The second calcined product obtained in step 2) was mixed with water in a mass ratio of 1:0.5 and washed, and then dried to obtain a washed second calcined product, and then 700 g of the washed second calcined product was mixed with 4 g of boric acid by a high-speed mixer, and calcined at 300 ° C for 6 h to obtain the modified high-nickel ternary positive electrode material.

[0093] Test Case

[0094] The modified high-nickel ternary positive electrode materials prepared in Examples 1-6 and Comparative Examples 1-4 were used as the main materials of the positive electrode materials to prepare positive electrode sheets, and then a lithium-ion battery was assembled. The specific steps were as follows: preparing positive electrode sheets, using N-methylpyrrolidone as a dispersant, mixing the main material: carbon black: polyvinylidene fluoride (PVDF): dispersant at a mass ratio of 90:5:5:100 to prepare a positive electrode slurry, and coating the positive electrode slurry evenly on a carbon-coated aluminum foil with a coating surface density of 12 cm 2 / mg, dried in an oven at 80°C for 2h to obtain a positive electrode sheet; in an argon atmosphere of a glove box, a Celgard 2500 separator and a lithium metal sheet were used as the negative electrode sheet, the electrolyte was 1 mol / L lithium hexafluorophosphate (LiPF6) in ethylene carbonate (EC) / dimethyl carbonate (DMC) solution, and the volume ratio of ethylene carbonate (EC) / dimethyl carbonate (DMC) was 1:1; a CR2032 button half-cell was assembled in the order of negative electrode sheet, electrolyte, separator, electrolyte, and positive electrode sheet.

[0095] Using the Blue Electric system, at 25°C, charge to 4.25V at a rate of 0.2C, and then discharge to 2.5V at a rate of 0.2C. This is a cycle process. The charge and discharge capacity this time is the first charge and discharge specific capacity, and the value of discharge specific capacity / charge specific capacity*100% is the first efficiency. After 2 cycles, charge at 1C and discharge at 1C for 50 cycles, record the charge and discharge capacity of the 3rd cycle and the charge and discharge capacity of the 52nd cycle, and the cycle capacity retention rate is the ratio of the discharge capacity of the 52nd cycle to the 3rd cycle*100%. The test results are shown in Table 1.

[0096] Table 1

[0097]

[0098]

[0099] As can be seen from Table 1, the specific capacity, first efficiency and cycle performance of the modified high-nickel ternary positive electrode material obtained by the preparation method of the present invention are significantly better than those of the comparative example, especially the modified high-nickel ternary positive electrode material obtained by the coordinated coating of potassium tellurite and sodium tellurite in Example 3, which has better specific capacity, first efficiency and cycle performance.

[0100] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for preparing a modified high-nickel ternary positive electrode material, characterized in that: The following steps are involved: 1) mixing a lithium source, a precursor, a tellurium source and a divalent metal compound, and performing a first calcination to obtain a calcined product; 2) dissolving the tellurate in an organic solvent, mixing the formed tellurate organic solvent solution with the first sintered product obtained in step 1), grinding the mixture, and then subjecting the mixture to a second calcination to obtain a second sintered product; The tellurite is selected from at least one of potassium tellurite and sodium tellurite; 3) The second calcined product obtained in step 2) is washed with water and mixed with boric acid, and then calcined for the third time to obtain the modified high-nickel ternary positive electrode material.

2. The method for preparing the modified high-nickel ternary positive electrode material according to claim 1, characterized in that: The divalent metal compound in step 1) is at least one selected from cobaltous hydroxide, strontium carbonate, magnesium oxide, and calcium oxide; The tellurite is potassium tellurite and sodium tellurite; The molar amount of nickel in the precursor accounts for more than 90% of the total molar amount of metal elements in the precursor; The lithium source is selected from at least one of lithium hydroxide and lithium carbonate; The tellurium source in step 1) is selected from tellurium dioxide.

3. The method for preparing the modified high-nickel ternary positive electrode material according to claim 1 or 2, characterized in that: The chemical formula of the precursor in step 1) is Ni x Co y Mn z O2, and 0.9≤x≤0.99, 0.01≤y≤0.09, 0.01≤z≤0.09, x+y+z=1; In step 1), the ratio of the total molar amount of metal elements in the precursor, the molar amount of tellurium elements in the tellurium source, and the molar amount of divalent metal elements in the divalent metal compound is (0.975-1): (0.0001-0.015): (0.0001-0.01); In step 1), the sum of the total molar amount of metal elements in the precursor, the molar amount of tellurium elements in the tellurium source and the molar amount of divalent metal elements in the divalent metal compound is recorded as a, and the molar amount of lithium elements in the lithium source is recorded as b, and b:a is (1.01-1.06):

1.

4. The method for preparing the modified high-nickel ternary positive electrode material according to any one of claims 1 to 3, characterized in that: In step 1), the first calcination temperature is 700-850° C. and the first calcination time is 8-16 hours; The calcination atmosphere of the first calcination in step 1) includes an oxygen-containing atmosphere.

5. The method for preparing the modified high-nickel ternary positive electrode material according to any one of claims 1 to 4, characterized in that: In step 2), the organic solvent is selected from ethanol; In step 2), the tellurate is dissolved in an organic solvent, and the mass concentration of the tellurium element in the formed tellurate organic solvent solution is 0.01-0.1wt%; The mass ratio of the tellurite organic solvent solution in step 2) to the sintered product obtained in step 1) is (1-2):

2.

6. The method for preparing the modified high-nickel ternary positive electrode material according to any one of claims 1 to 5, characterized in that: The grinding speed is 300-600rpm, and the grinding time is 0.5-1h; Optionally, the grinding comprises ball milling; The second calcination temperature is 500-700°C, and the second calcination time is 6-12h; The second calcining atmosphere includes an oxygen-containing atmosphere.

7. The method for preparing the modified high-nickel ternary positive electrode material according to any one of claims 1 to 6, characterized in that: The second calcined product in step 3) is mixed with water and washed, and then dried to obtain a washed second calcined product, which is then mixed with boric acid and calcined for the third time to obtain the modified high-nickel ternary positive electrode material.

8. The method for preparing the modified high-nickel ternary positive electrode material according to claim 7, characterized in that: The mass ratio of the second burning product to water is 1:(0.5-1.0); The mass ratio of the washed second calcined product to boric acid is 700:(2-10); The third calcination temperature is 200-400° C., and the third calcination time is 5-11 hours.

9. A modified high-nickel ternary positive electrode material, characterized in that: The modified high-nickel ternary positive electrode material is prepared by the preparation method of any one of claims 1 to 8.

10. Use of the modified high-nickel ternary positive electrode material according to claim 9 in lithium-ion batteries.

Images