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

Abstract

The invention belongs to the technical field of positive electrode materials, and particularly relates to a modified high-nickel ternary positive electrode material and a preparation method and application thereof. The invention provides a preparation method of a modified high-nickel ternary positive electrode material, which comprises the following steps: mixing a doped element-containing high-nickel ternary positive electrode material, bismuth tungstate and aluminum oxide, and sintering to obtain the modified high-nickel ternary positive electrode material, the doping element comprises at least one of a titanium element, a yttrium element, a tungsten element and a niobium element; the sintering temperature ranges from 400 DEG C to 800 DEG C. The battery prepared from the modified high-nickel ternary positive electrode material prepared by the invention has good cycling stability and thermal stability.

Description

Technical Field

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

[0002] Lithium-ion batteries have been widely used in the field of new energy vehicles. Improving the energy density of lithium-ion batteries can effectively increase the cruising range of new energy vehicles. High-nickel ternary layered materials have the advantages of high specific capacity, low cost and high safety, and are considered to be one of the positive electrode materials in high-energy-density lithium-ion batteries.

[0003] However, as the nickel content in the ternary layered material increases, its cycle stability and thermal stability will decrease significantly. It has become a research difficulty to increase the nickel content in the ternary layered material to increase the energy density of the battery while ensuring the thermal stability and cycle stability of the ternary material. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of high-nickel ternary materials in the prior art, such as poor cycle stability and thermal stability, thereby providing a modified high-nickel ternary positive electrode material and its preparation method and application.

[0005] To this end, the present invention provides the following technical solutions.

[0006] The present invention provides a method for preparing a modified high-nickel ternary positive electrode material, comprising the following steps:

[0007] The high-nickel ternary positive electrode material containing doping elements, bismuth tungstate and aluminum oxide are mixed and sintered to obtain a modified high-nickel ternary positive electrode material;

[0008] The doping element includes at least one of titanium, yttrium, tungsten and niobium; and the sintering temperature is 400-800° C. Exemplarily, the sintering temperature is 400° C., 450° C., 500° C., 550° C., 600° C., 700° C., 800° C., or a range formed by any two of the above values.

[0009] In an optional embodiment, based on the mass of the high nickel ternary positive electrode material containing the doping element, the total amount of bismuth tungstate and aluminum oxide added is 0.05-0.7wt%. In the present invention, there is no requirement for the mass ratio of bismuth tungstate and aluminum oxide. When the mass ratio of bismuth tungstate and aluminum oxide is (1-3):1, the cycle stability and thermal stability of the modified high nickel ternary material can be optimized.

[0010] In an optional embodiment, the preparation steps of the high-nickel ternary positive electrode material containing doping elements include: mixing a precursor, a lithium source and an additive containing the doping element, and heat treating to obtain the high-nickel ternary positive electrode material containing the doping element.

[0011] In an optional embodiment, the precursor includes nickel cobalt manganese hydroxide, and the chemical composition of the nickel cobalt manganese hydroxide includes Ni x Co y Mn 1-x-y (OH)2, 0.7≤x<1, 0<y≤0.1; In the present invention, the subscripts x and y in the chemical structural formula represent the molar ratio of each element.

[0012] In an optional embodiment, the lithium source includes at least one of lithium hydroxide and lithium carbonate;

[0013] In an optional embodiment, based on the mass of the precursor, the amount of the additive containing the doping element is 0.05-0.8wt%. In the present invention, the additive containing the doping element may include at least one of a titanium-containing compound, a yttrium-containing compound, a tungsten-containing compound and a niobium-containing compound. Exemplarily, the additive containing the doping element includes a titanium-containing compound and a yttrium-containing compound, the additive containing the doping element includes a titanium-containing compound and a niobium-containing compound, the additive containing the doping element includes a titanium-containing compound, a tungsten-containing compound and a niobium-containing compound, the additive containing the doping element includes a titanium-containing compound, a yttrium-containing compound, a tungsten-containing compound and a niobium-containing compound, and the additive containing the doping element includes a yttrium-containing compound, a tungsten-containing compound and a niobium-containing compound.

[0014] In an optional embodiment, the ratio of the total molar amount of nickel, cobalt and manganese in the precursor to the molar amount of lithium in the lithium source is 1:(1.02-1.06).

[0015] In an optional embodiment, the heat treatment is performed under an oxygen atmosphere;

[0016] In an optional embodiment, the temperature of the heat treatment is 600-900°C;

[0017] In an optional embodiment, the heating rate of the heat treatment is 1-5°C / min;

[0018] In an optional embodiment, the heat treatment time is 8-15 hours.

[0019] In an optional embodiment, the sintering is performed in an oxygen atmosphere;

[0020] In an optional embodiment, the heating rate of the sintering is 1.5-5°C / min;

[0021] In an optional embodiment, the sintering time is 3-7 hours.

[0022] In the present invention, the oxygen atmosphere is mainly an oxygen atmosphere, for example, the oxygen atmosphere can be a pure oxygen atmosphere; the oxygen atmosphere can also include a small amount of other gases, such as nitrogen.

[0023] The present invention also provides a modified high-nickel ternary positive electrode material obtained by the above preparation method.

[0024] The present invention also provides an application of the modified high-nickel ternary positive electrode material prepared by the above preparation method in a lithium ion battery.

[0025] The technical solution of the present invention has the following advantages:

[0026] 1. The preparation method of the modified high-nickel ternary positive electrode material provided by the present invention comprises the following steps: mixing a high-nickel ternary positive electrode material containing doping elements, bismuth tungstate and aluminum oxide, sintering to obtain a modified high-nickel ternary positive electrode material; the doping element comprises at least one of titanium, yttrium, tungsten and niobium; the sintering temperature is 400-800°C. The modified high-nickel ternary positive electrode material prepared by the present invention has good cycle stability and thermal stability of the battery, and is coated with bismuth tungstate, which decomposes into tungsten oxide and bismuth oxide under high temperature environment, and the stable element bismuth with the largest atomic radius enters the lattice of the high-nickel ternary material containing doping elements to increase the interlayer distance of the high-nickel ternary material, support the structure of the ternary material, and improve the surface stability; the tungsten oxide formed by the decomposition of bismuth tungstate and the added aluminum oxide form a coating layer on the surface of the high-nickel ternary positive electrode material containing doping elements, inhibiting interface side reactions and improving the cycle stability and thermal stability; the coating layer and the doping of bismuth element on the surface of the ternary positive electrode material can be formed by mixing bismuth tungstate and aluminum oxide, and the steps are simple and the cost is low. Adding doping elements can improve the cycle performance and thermal stability of the battery made of the modified high-nickel ternary positive electrode material together with the coating layer. Furthermore, adding doping elements when preparing the high-nickel ternary positive electrode material can allow at least one element of titanium, yttrium, tungsten and niobium to enter the high-nickel ternary positive electrode material to form doping, thereby improving the structural stability of the ternary material and thus improving the cycle performance of the positive electrode material. DETAILED DESCRIPTION

[0027] 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.

[0028] 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.

[0029] Example 1

[0030] This embodiment provides a method for preparing a modified high-nickel ternary positive electrode material, comprising the following steps:

[0031] (1) Ni 0.8 Co 0.1 Mn 0.1 The (OH)2 precursor, lithium hydroxide, titanium oxide, yttrium oxide and tungsten oxide were mixed evenly, heated to 750℃ at 2.5℃ / min in an oxygen atmosphere for 10h, and naturally cooled to room temperature to obtain a ternary material; wherein Ni 0.8 Co 0.1 Mn 0.1 The ratio of the total molar amount of nickel, cobalt and manganese in the (OH)2 precursor to the molar amount of lithium in lithium hydroxide is 1:1.04; Ni 0.8 Co 0.1 Mn 0.1 The mass ratio of (OH)2 precursor, titanium oxide, yttrium oxide and tungsten oxide is 1:0.001:0.002:0.001.

[0032] (2) The above-mentioned ternary material, bismuth tungstate and aluminum oxide were mixed evenly in a mass ratio of 1:0.002:0.002, heated to 600°C at 2°C / min in an oxygen atmosphere, sintered for 4 hours, and naturally cooled to room temperature to obtain a modified high-nickel ternary positive electrode material.

[0033] Example 2

[0034] This embodiment provides a method for preparing a modified high-nickel ternary positive electrode material, comprising the following steps:

[0035] (1) Ni 0.9 Co 0.05 Mn 0.05 The (OH)2 precursor, lithium hydroxide, niobium oxide, tungsten oxide and titanium oxide were mixed evenly, heated to 700℃ at 3.1℃ / min in an oxygen atmosphere for 10h, and naturally cooled to room temperature to obtain a ternary material; among them, Ni 0.9 Co 0.05 Mn 0.05 The ratio of the total molar amount of nickel, cobalt and manganese in the (OH)2 precursor to the molar amount of lithium in lithium hydroxide is 1:1.04; Ni 0.8 Co0.1 Mn 0.1 The mass ratio of (OH)2 precursor, niobium oxide, tungsten oxide and titanium oxide is 1:0.002:0.002:0.001.

[0036] (2) The above-mentioned ternary material, bismuth tungstate and aluminum oxide were mixed evenly in a mass ratio of 1:0.002:0.001, heated to 500°C at 2°C / min in an oxygen atmosphere, sintered for 4 hours, and naturally cooled to room temperature to obtain a modified high-nickel ternary positive electrode material.

[0037] Example 3

[0038] This embodiment provides a method for preparing a modified high-nickel ternary positive electrode material, comprising the following steps:

[0039] (1) Ni 0.7 Co 0.1 Mn 0.2 The (OH)2 precursor, lithium hydroxide, niobium oxide, tungsten oxide and titanium oxide were mixed evenly, heated to 900℃ at 5℃ / min for 15h in an oxygen atmosphere, and naturally cooled to room temperature to obtain a ternary material; wherein Ni 0.7 Co 0.1 Mn 0.2 The ratio of the total molar amount of nickel, cobalt and manganese in the (OH)2 precursor to the molar amount of lithium in lithium hydroxide is 1:1.06; 0.7 Co 0.1 Mn 0.2 The mass ratio of (OH)2 precursor, niobium oxide, tungsten oxide and titanium oxide is 1:0.0005:0.0005:0.0005.

[0040] (2) The above-mentioned ternary material, bismuth tungstate and aluminum oxide were mixed evenly in a mass ratio of 1:0.003:0.003, heated to 800°C at 5°C / min in an oxygen atmosphere, sintered for 7h, and naturally cooled to room temperature to obtain a modified high-nickel ternary positive electrode material.

[0041] Comparative Example 1

[0042] This comparative example provides a method for preparing a ternary material, comprising the following steps:

[0043] (1) Ni 0.8 Co 0.1 Mn 0.1 The (OH)2 precursor, lithium hydroxide, titanium oxide, yttrium oxide and tungsten oxide were mixed evenly, heated to 750℃ at 2.5℃ / min in an oxygen atmosphere for 10h, and naturally cooled to room temperature to obtain a ternary material; wherein Ni 0.8 Co 0.1 Mn 0.1The ratio of the total molar amount of nickel, cobalt and manganese in the (OH)2 precursor to the molar amount of lithium in lithium hydroxide is 1:1.04; Ni 0.8 Co 0.1 Mn 0.1 The mass ratio of (OH)2 precursor, titanium oxide, yttrium oxide and tungsten oxide is 1:0.001:0.002:0.001.

[0044] (2) The above-mentioned ternary material, tungsten oxide and aluminum oxide were mixed evenly in a mass ratio of 1:0.002:0.002, heated to 600°C at 2°C / min in an oxygen atmosphere, sintered for 4 hours, and naturally cooled to room temperature to obtain a modified ternary material.

[0045] Comparative Example 2

[0046] This comparative example provides a method for preparing a ternary material, comprising the following steps:

[0047] (1) Ni 0.9 Co 0.05 Mn 0.05 The (OH)2 precursor, lithium hydroxide, niobium oxide, tungsten oxide, bismuth oxide and titanium oxide were mixed evenly, heated to 700℃ at 3.1℃ / min in an oxygen atmosphere for 10h, and naturally cooled to room temperature to obtain a ternary material; among them, Ni 0.9 Co 0.05 Mn 0.05 The ratio of the total molar amount of nickel, cobalt and manganese in the (OH)2 precursor to the molar amount of lithium in lithium hydroxide is 1:1.04; Ni 0.9 Co 0.05 Mn 0.05 The mass ratio of (OH)2 precursor, niobium oxide, tungsten oxide and titanium oxide is 1:0.002:0.002:0.001.

[0048] (2) The above-mentioned ternary material, bismuth oxide and aluminum oxide are mixed evenly in a mass ratio of 1:0.002:0.002, heated to 600°C at 2°C / min in an oxygen atmosphere, sintered for 4 hours, and naturally cooled to room temperature to obtain a modified ternary material.

[0049] Comparative Example 3

[0050] This comparative example provides a method for preparing a ternary material. Compared with Example 1, the only difference is that step (1) is different and titanium oxide, yttrium oxide and tungsten oxide are not added in step (1).

[0051] Comparative Example 4

[0052] This comparative example provides a method for preparing a ternary material. Compared with Example 1, the only difference is that step (2) is different. In step (2), the temperature is increased to 300°C at 2°C / min and sintered for 4 hours instead of the temperature increased to 600°C at 2°C / min and sintered for 4 hours in Example 1.

[0053] Comparative Example 5

[0054] This comparative example provides a method for preparing a ternary material. Compared with Example 2, the only difference is that step (2) is different. In step (2), the temperature is increased to 900°C at 2°C / min and sintered for 4 hours instead of the temperature increased to 500°C at 2°C / min and sintered for 4 hours in Example 2.

[0055] Test Case

[0056] The performance tests of the ternary materials prepared in Examples 1-3 and Comparative Examples 1-5 are as follows:

[0057] The ternary material, polyvinylidene fluoride (PVDF), and Super P (SP) were weighed and homogenized according to the mass ratio of 97.2:1.3:1.5, and then the aluminum foil was spread on the coating machine for coating (surface density of 15-17 mg / cm 2 ), put it into an 80℃ forced air drying oven and dry it for 2h; then punch, weigh, bake the electrode, and make it into a CR2032 button battery.

[0058] The performance test of the battery prepared above is as follows:

[0059] (1) Cycle performance test: At room temperature, the battery was placed in a blue-electric test system, the charging voltage was 3.0-4.3 V, the charge and discharge rate was 1C, and the number of cycles was 100. The results are shown in Table 1. The cycle performance is the ratio of the discharge capacity at the 100th cycle to the discharge capacity at the 1st cycle.

[0060] (2) Thermal stability test method: at 45°C, place the battery in a blue battery test system, with a charging voltage of 3.0-4.3V, a charge and discharge rate of 1C, and 100 cycles. The results are shown in Table 1. Thermal stability refers to the ratio of the discharge capacity at the 100th cycle to the discharge capacity at the 1st cycle at 45°C.

[0061] Table 1

[0062] Cycle performance % Thermal stability % Example 1 96.4 95.2 Example 2 94.5 93.1 Example 3 97.1 95.8 Comparative Example 1 92.3 91.2 Comparative Example 2 91.2 89.9 Comparative Example 3 91.1 89.1 Comparative Example 4 90.2 88.8 Comparative Example 5 92.1 91.4

[0063] It can be seen from Table 1 that the battery made from the modified high-nickel ternary positive electrode material prepared in the present invention has good cycle performance and good thermal stability.

[0064] It can be seen from Examples 1-3 and Comparative Examples 1-5 that the present invention first prepares a high-nickel ternary positive electrode material containing doping elements, then adds bismuth tungstate and aluminum oxide and sintering at 400-800°C to obtain a modified high-nickel ternary positive electrode material, which can significantly improve the cycle performance and thermal stability of the battery made of the material. When the temperature is less than 400°C, bismuth tungstate cannot be decomposed at high temperature, and there is no aluminum oxide and tungsten oxide coating and bismuth oxide surface modification. The cycle performance and thermal stability of the battery made of the prepared ternary material are significantly reduced; when the temperature is greater than 800°C, the cycle performance and thermal stability of the battery made of the prepared modified high-nickel ternary material will deteriorate.

[0065] 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 from these are still within the scope of protection of the invention.

Claims

1. A method for preparing a modified high-nickel ternary positive electrode material, characterized in that: The steps include: The high-nickel ternary positive electrode material containing doping elements, bismuth tungstate and aluminum oxide are mixed and sintered to obtain a modified high-nickel ternary positive electrode material; The doping element includes at least one of titanium, yttrium, tungsten and niobium; The sintering temperature is 400-800°C.

2. The preparation method according to claim 1, characterized in that: Based on the mass of the high-nickel ternary positive electrode material containing doping elements, the total added amount of the bismuth tungstate and aluminum oxide is 0.05-0.7wt%.

3. The preparation method according to claim 1 or 2, characterized in that: The preparation steps of the high-nickel ternary positive electrode material containing doping elements include: mixing a precursor, a lithium source and an additive containing the doping element, and heat treating to obtain the high-nickel ternary positive electrode material containing the doping element.

4. The preparation method according to claim 3, characterized in that: The precursor includes nickel-cobalt-manganese hydroxide, and the chemical composition of the nickel-cobalt-manganese hydroxide includes Ni x Co y Mn 1-x-y (OH)2, 0.7≤x<1, 0<y≤0.1; and / or, The lithium source comprises at least one of lithium hydroxide and lithium carbonate; and / or, Based on the mass of the precursor, the amount of the additive containing the doping element is 0.05-0.8wt%.

5. The preparation method according to claim 4, characterized in that: The ratio of the total molar amount of nickel, cobalt and manganese in the precursor to the molar amount of lithium in the lithium source is 1:(1.02-1.06).

6. The preparation method according to claim 3, characterized in that: The heat treatment is carried out in an oxygen atmosphere; and / or, The heat treatment temperature is 600-900°C; and / or, The heating rate of the heat treatment is 1-5°C / min; and / or, The heat treatment time is 8-15h.

7. The preparation method according to claim 1, characterized in that: The sintering is performed in an oxygen atmosphere.

8. The preparation method according to claim 7, characterized in that: The heating rate of the sintering is 1.5-5°C / min; and / or, The sintering time is 3-7h.

9. A modified high-nickel ternary positive electrode material obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the modified high-nickel ternary positive electrode material prepared by the preparation method according to any one of claims 1 to 8 in a lithium-ion battery.