Lithium nickel cobalt aluminate positive electrode material as well as preparation method and application thereof

Abstract

The invention provides a lithium nickel cobalt aluminate positive electrode material and a preparation method and application thereof, and the preparation method comprises the following steps: mixing and sintering a lithium nickel cobalt aluminate primary sintering material and a cobalt source to obtain a secondary sintering material; and mixing and sintering a tungsten source, a lithium source and the secondary sintering material to obtain the nickel cobalt lithium aluminate positive electrode material. According to the preparation method disclosed by the invention, a fast ion conductor layer is formed by firstly coating a cobalt source and then coating a tungsten source and a lithium source, and meanwhile, the cobalt source and the lithium source in secondary coating form a lithium cobalt oxide coating layer, so that a surface layered structure of the positive electrode material is reconstructed, and a lithium cobalt oxide coating layer and a lithium tungstate coating layer are generated on the surface of nickel cobalt lithium aluminate; the interface characteristic of the positive electrode material is improved, and the cycle performance of the material is improved while the discharge capacity is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries and relates to a nickel cobalt aluminum oxide lithium cathode material and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries have been widely studied due to their advantages such as high energy density, long service life, stable operating voltage, light weight and environmental friendliness, and have been successfully applied in many fields such as portable consumer electronics, new energy vehicles and storage systems. As one of the main materials of lithium-ion batteries, the performance of the positive electrode material determines the performance of the battery to a certain extent. Among them, NCA (LiNi 1-x-y Co x Al y O2) is a positive electrode material with great commercial potential. NCA material has a high reversible specific capacity, and Al doping enhances the structural stability of the material. At present, with the demand of battery manufacturers for higher capacity density of batteries, nickel cobalt aluminum oxide materials are developing towards higher nickel content. However, ternary materials with higher nickel content are more prone to lithium-nickel mixing, resulting in poor structural stability, and then poor cycle performance. Therefore, it is necessary to develop a preparation method for nickel cobalt aluminum oxide ternary positive electrode material to prepare nickel cobalt aluminum ternary positive electrode material with better cycle performance while ensuring higher capacity.

[0003] For example, CN 116387495A discloses an oxygen vacancy tungsten oxide coated cathode material, a preparation method, and a lithium battery. The provided oxygen vacancy tungsten oxide coated cathode material comprises a substrate and an oxygen vacancy tungsten oxide coating layer on the surface of the substrate, wherein the substrate is composed of LiNi 1-x M x O2, x≤0.25, M element includes at least one of Co and Mn, and the composition of oxygen vacancy tungsten oxide is OV-W 18 O 49 That is, it obtains oxygen vacancy tungsten oxide through special treatment, and then wet-coated it on the surface of the positive electrode material. However, due to the damage to the material caused by the wet method, its cycle performance is poor.

[0004] For example, CN 113823761A discloses a tungsten-coated positive electrode material, a preparation method, a positive electrode sheet, and a lithium-ion battery. The preparation method of the tungsten-coated positive electrode material comprises: pressing the positive electrode material to obtain a sheet; coating the sheet with a tungsten coating layer by a vacuum coating method to obtain a coated sheet; and crushing the coated sheet to obtain a tungsten-coated positive electrode material. The use of the vacuum coating method to coat the positive electrode material with tungsten effectively improves the cycle performance of the material. However, the vacuum membrane has high cost, poor industrial conversion, and low capacity.

[0005] Based on the above research, it is necessary to provide a method for preparing a nickel cobalt aluminum oxide positive electrode material, which can improve the cycle performance of the material while increasing the discharge capacity, and at the same time improve the interface characteristics of the positive electrode material, thereby obtaining a nickel cobalt aluminum oxide positive electrode material with high capacity and excellent cycle performance. Summary of the Invention

[0006] The object of the present invention is to provide a nickel cobalt aluminum oxide positive electrode material and its preparation method and application. The preparation method forms a fast ion conductor layer by first coating a cobalt source and then coating a tungsten source and a lithium source. At the same time, the cobalt source and the lithium source during the second coating form a lithium cobalt oxide coating layer, thereby reconstructing the layered structure of the positive electrode material surface, thereby generating lithium cobalt oxide and lithium tungstate coating layers on the surface of the lithium nickel cobalt aluminum oxide, improving the interface characteristics of the positive electrode material, and improving the cycle performance of the material while increasing the discharge capacity.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a lithium nickel cobalt aluminum oxide positive electrode material, the preparation method comprising the following steps:

[0009] (1) mixing and sintering a lithium nickel cobalt aluminum oxide first sinter and a cobalt source to obtain a second sinter;

[0010] (2) Mixing and sintering the tungsten source, the lithium source and the second sintered material of step (1) to obtain the lithium nickel cobalt aluminum oxide positive electrode material.

[0011] The present invention uses step-by-step sintering to first coat the cobalt source, so that the cobalt coats and penetrates into the first sintered material at the same time, forming a shallow surface layer of cobalt doping (which can improve the bonding strength between the coating layer and the core), and then mixes and sinters the first sintered material with the W source and the Li source. The W source and the Li source further react to obtain a lithium tungstate fast ion conductor (Li2WO4), and at the same time, the surface Co and the Li source further react to obtain lithium cobaltate, so that the lithium tungstate fast ion conductor and the lithium cobaltate mixed coating improve the interface transmission of Li and inhibit side reactions, thereby solving the problem of surface Ni 3+ The problem of poor cycle performance caused by instability is solved by improving the electrochemical performance of the material.

[0012] At the same time, the lithium cobalt oxide and lithium tungstate coating of the present invention have a synergistic effect, which effectively isolates the contact between the electrolyte and the positive electrode material, provides a fast lithium ion conduction channel, reduces the occurrence of electrolyte side reactions, and enhances the cycle stability and rate performance of the material.

[0013] Preferably, the sintering temperature in step (1) is greater than the sintering temperature in step (2).

[0014] The present invention coats the cobalt source at a high temperature, which can promote cobalt coating and achieve shallow surface doping at the same time. When tungsten is coated at a lower temperature, if the temperature for coating the cobalt is too low, shallow surface doping of the cobalt element cannot be achieved, and a thick coating layer will be formed on the surface, hindering the transmission of lithium ions; if the temperature for coating the cobalt is too high, the cobalt element is incorporated into the lithium nickel cobalt aluminum oxide core, the Co coating layer basically does not exist, and a lithium cobalt oxide coating layer cannot be formed on the surface; if the temperature for coating the tungsten is too high, the tungsten element is embedded in the layered structure, causing the primary particles to grow slenderly, which is not conducive to the thermal stability of the material; if the temperature for coating the tungsten is too low, it is difficult to form a lithium tungstate fast ion conductor coating layer on the surface.

[0015] Preferably, the sintering temperature in step (1) is 500-600°C, for example, 520°C, 550°C, 570°C or 600°C, and the sintering time is 6-10h, for example, 7h, 8h, 9h or 10h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0016] Preferably, the sintering in step (1) is carried out in an oxygen atmosphere.

[0017] Preferably, based on the mass of the lithium nickel cobalt aluminum oxide sintered material in step (1), the amount of the cobalt source added in step (1) is 5000-12000 ppm, for example, it can be 7000 ppm, 9000 ppm, 11000 ppm or 12000 ppm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] Preferably, the cobalt source in step (1) includes Co3O4 and / or CoOOH.

[0019] Preferably, the method for preparing the lithium nickel cobalt aluminum oxide sinter in step (1) comprises the following steps:

[0020] The high nickel precursor, aluminum source, doping source and lithium salt are mixed and calcined to obtain the lithium nickel cobalt aluminum oxide sintered material.

[0021] Preferably, the chemical formula of the high nickel precursor is Ni x Co y (OH)2, wherein 0.9≤x<1, for example, it can be 0.9, 0.92, 0.94, 0.96, 0.98 or 0.99, and 0<y<0.1, for example, it can be 0.02, 0.04, 0.06, 0.08 or 0.09, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0022] Preferably, the particle size D50 of the high nickel precursor is 10-15 μm, for example, 12 μm, 14 μm or 15 μm, and the BET is 1-4 μm. 2 / g, for example, it can be 1m 2 / g, 2m 2 / g、3m 2 / g or 4m 2 / g, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0023] Preferably, the doping source includes a zirconium source and / or a magnesium source.

[0024] The present invention adopts the NC precursor fire method to dope Al, Zr and Mg, and reduces the lithium-nickel mixing, stabilizes the internal structure and improves the lithium ion diffusion coefficient through the joint action of Al(OH)3, ZrO2 and MgO.

[0025] Preferably, the doping amount of the doping source is 0.01-0.03wt% of the lithium nickel cobalt aluminum oxide sinter, for example, it can be 0.01wt%, 0.02wt% or 0.03wt%, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the aluminum source comprises Al(OH)3 and / or Al2O3.

[0027] Preferably, the lithium salt includes LiOH·H2O and / or Li2CO3, and the lithiation ratio is 1.01-1.06, for example, 1.02, 1.04 or 1.06, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] Preferably, the calcination temperature is 700-1000° C., such as 800° C., 900° C. or 1000° C., the calcination time is 8-12 h, such as 9 h, 10 h, 11 h or 12 h, and the atmosphere is an oxygen atmosphere.

[0029] Preferably, based on the mass of the second sintered material in step (2), the amount of tungsten source added in step (2) is 1000-2000ppm, for example, it can be 1200ppm, 1400ppm, 1600ppm, 1800ppm or 2000ppm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] Preferably, based on the mass of the second sintered material in step (2), the amount of the lithium source added in step (2) is 1000-4000 ppm, for example, 2000 ppm, 3000 ppm or 4000 ppm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 3000-4000 ppm.

[0031] The amount of lithium source added when coating tungsten in the present invention should be greater than the amount of tungsten source added to ensure that the cobalt on the surface can also react with the lithium source. Therefore, the amount of lithium source added should not be too small, but if the lithium source is too much, there is a risk of excessive residual alkali.

[0032] Preferably, the tungsten source in step (2) comprises WO 2.72 , WO3 or tungstic acid, or a combination of at least two thereof.

[0033] Preferably, the sintering temperature in step (2) is 200-400°C, for example, 200°C, 300°C or 400°C, and the sintering time is 3-6h, for example, 4h, 5h or 6h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0034] Preferably, the sintering atmosphere in step (2) is an oxygen atmosphere.

[0035] As a preferred technical solution of the preparation method of the present invention, the preparation method comprises the following steps:

[0036] (1) mixing a high nickel precursor, an aluminum source, a doping source and a lithium salt, and then calcining at a temperature of 700-1000° C. for 8-12 hours in an oxygen atmosphere to obtain the lithium nickel cobalt aluminum oxide sinter;

[0037] The general chemical formula of the high nickel precursor is Ni x Co y (OH)2, where 0.9≤x<1, 0<y<0.1, the particle size D50 of the high nickel precursor is 10-15μm, and the BET is 1-4m 2 / g, the doping amount of the doping source is 0.01-0.03wt% of the lithium nickel cobalt aluminum oxide sinter;

[0038] (2) mixing the cobalt source and the lithium nickel cobalt aluminum oxide first sinter described in step (1), and then sintering at a temperature of 500-600° C. for 6-10 hours in an oxygen atmosphere to obtain a second sinter;

[0039] Based on the mass of the lithium nickel cobalt aluminum oxide sinter, the amount of the cobalt source added is 5000-12000ppm;

[0040] (3) mixing a tungsten source, a lithium source and the second sintered material of step (2), and then sintering at a temperature of 200-400° C. for 3-6 hours in an oxygen atmosphere to obtain the lithium nickel cobalt aluminum oxide positive electrode material;

[0041] Based on the mass of the second-sintered material, the added amount of the tungsten source is 1000-2000 ppm, and the added amount of the lithium source is 3000-4000 ppm.

[0042] In a second aspect, the present invention provides a lithium nickel cobalt aluminum oxide positive electrode material, which is prepared using the preparation method described in the first aspect.

[0043] In a third aspect, the present invention provides a lithium-ion battery, comprising the lithium nickel cobalt aluminum oxide positive electrode material as described in the second aspect.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The present invention coats a cobalt source to form a shallow cobalt doping layer on the surface of the particles, and then coats a W source and a Li source. The W source and the Li source further react to obtain a lithium tungstate fast ion conductor. At the same time, the Co coated on the surface further reacts with the Li source to obtain lithium cobaltate. The mixed coating layer of the lithium tungstate fast ion conductor and the lithium cobaltate can improve the interface transmission of Li and inhibit side reactions, thereby improving the cycle performance of the material while increasing the discharge capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a scanning electron microscope image of the lithium nickel cobalt aluminum oxide positive electrode material obtained by the preparation method described in Example 1 of the present invention. DETAILED DESCRIPTION

[0047] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0048] Example 1

[0049] This embodiment provides a method for preparing a lithium nickel cobalt aluminum oxide positive electrode material, the preparation method comprising the following steps:

[0050] (1) mixing a high nickel precursor with LiOH according to a lithiation ratio (Ni+Co:Li=1:1.03), then adding 0.016wt% of Al(OH)3, 0.032wt% of ZrO2, and 0.012wt% of MgO, mixing in a high speed mixer at 600rpm for 15 minutes, and then calcining at 700°C for 10 hours in an oxygen atmosphere to obtain the lithium nickel cobalt aluminum oxide sinter;

[0051] The high nickel precursor is Ni 0.94 Co 0.06 (OH)2, particle size D50 is 10μm, BET is 4m 2 / g;

[0052] (2) CoOOH and the lithium nickel cobalt aluminum oxide first sintered material described in step (1) were mixed in a high-speed mixer at a speed of 800 rpm for 15 minutes, and then sintered at a temperature of 600° C. for 10 hours under an oxygen atmosphere. After naturally cooling to room temperature, the material was taken out and sieved to obtain a second sintered material;

[0053] Based on the mass of the lithium nickel cobalt aluminum oxide sinter, the amount of CoOOH added is 6000ppm;

[0054] (3) Will WO 2.72 , LiOH and the second sintered material of step (2) are mixed in a high-speed mixer at a speed of 600 rpm for 15 minutes, and then sintered at a temperature of 400 ° C for 5 hours under an oxygen atmosphere. The material is cooled to room temperature and sieved to obtain the lithium nickel cobalt aluminum oxide positive electrode material. The morphology of the lithium nickel cobalt aluminum oxide positive electrode material is shown in FIG. Figure 1 As shown;

[0055] Based on the quality of the second fired material, the WO 2.72 The addition amount of is 1000ppm, and the addition amount of LiOH is 4000ppm.

[0056] Example 2

[0057] This embodiment provides a method for preparing a lithium nickel cobalt aluminum oxide positive electrode material, the preparation method comprising the following steps:

[0058] (1) mixing a high nickel precursor with LiOH according to a lithiation ratio (Ni+Co:Li=1:1.03), then adding 0.016wt% of Al(OH)3, 0.032wt% of ZrO2, and 0.012wt% of MgO, mixing in a high speed mixer at 600rpm for 15 minutes, and then calcining at 1000°C for 8 hours in an oxygen atmosphere to obtain the lithium nickel cobalt aluminum oxide sinter;

[0059] The high nickel precursor is Ni 0.94 Co 0.06 (OH)2, particle size D50 is 15μm, BET is 1m 2 / g;

[0060] (2) CoOOH and the lithium nickel cobalt aluminum oxide first sintered material described in step (1) were mixed in a high-speed mixer at a speed of 800 rpm for 15 minutes, and then sintered at a temperature of 500° C. for 6 hours under an oxygen atmosphere. After naturally cooling to room temperature, the material was taken out and sieved to obtain a second sintered material;

[0061] Based on the mass of the lithium nickel cobalt aluminum oxide sinter, the amount of CoOOH added is 12000ppm;

[0062] (3) Will WO 2.72, LiOH and the second sintered material of step (2) are mixed in a high-speed mixer at a speed of 600 rpm for 15 minutes, and then sintered at a temperature of 200° C. for 6 hours under an oxygen atmosphere, and the discharged material is cooled to room temperature and sieved to obtain the lithium nickel cobalt aluminum oxide positive electrode material;

[0063] Based on the quality of the second fired material, the WO 2.72 The addition amount of is 2000ppm, and the addition amount of LiOH is 3000ppm.

[0064] Example 3

[0065] This embodiment provides a method for preparing a lithium nickel cobalt aluminum oxide positive electrode material. The preparation method is the same as that of Example 1 except that the amount of LiOH added in step (3) is 2000 ppm.

[0066] Example 4

[0067] This embodiment provides a method for preparing a lithium nickel cobalt aluminum oxide positive electrode material. The preparation method is the same as that of Example 1 except that the amount of LiOH added in step (3) is 1000 ppm.

[0068] Example 5

[0069] This embodiment provides a method for preparing a lithium nickel cobalt aluminum oxide positive electrode material. The preparation method is the same as that of Example 1 except that the amount of LiOH added in step (3) is 6000 ppm.

[0070] Example 6

[0071] This embodiment provides a method for preparing a lithium nickel cobalt aluminum oxide positive electrode material. The preparation method is the same as that of Example 1, except that the sintering temperature in step (2) is 400° C., so that the sintering temperatures in step (2) and step (3) are the same.

[0072] Example 7

[0073] This embodiment provides a method for preparing a lithium nickel cobalt aluminum oxide positive electrode material. The preparation method is the same as that of Example 1 except that the sintering temperature in step (2) is 700°C.

[0074] Example 8

[0075] This embodiment provides a method for preparing a lithium nickel cobalt aluminum oxide positive electrode material. The preparation method is the same as that of Example 1, except that the sintering temperature in step (3) is 600° C., making the sintering temperatures in steps (2) and (3) the same.

[0076] Example 9

[0077] This embodiment provides a method for preparing a lithium nickel cobalt aluminum oxide positive electrode material. The preparation method is the same as that of Example 1 except that the sintering temperature in step (3) is 150° C.

[0078] Comparative Example 1

[0079] This comparative example provides a method for preparing a lithium nickel cobalt aluminum oxide positive electrode material. The preparation method is the same as Example 1 except that step (3) is not performed and the tungsten source and the lithium source are mixed and sintered together with the cobalt source in step (2).

[0080] The step (2) of this comparative example is: CoOOH, WO 2.72 , LiOH and the lithium nickel cobalt aluminum oxide first sintered material of step (1) are mixed in a high-speed mixer at a speed of 800 rpm for 15 minutes, and then sintered at a temperature of 600° C. for 10 hours under an oxygen atmosphere. After naturally cooling to room temperature, the material is taken out and sieved to obtain a second sintered material;

[0081] Based on the mass of the lithium nickel cobalt aluminum oxide sintered in step (1), the amount of CoOOH added is 6000ppm, and the WO 2.72 The addition amount of is 1000ppm, and the addition amount of LiOH is 4000ppm.

[0082] Comparative Example 2

[0083] This comparative example provides a method for preparing a lithium nickel cobalt aluminum oxide positive electrode material, the preparation method including the following steps:

[0084] (1) Step (1) of this comparative example is the same as that of Example 1;

[0085] (2) mixing the lithium nickel cobalt aluminum oxide first sintered material described in step (1) in a high-speed mixer at a speed of 800 rpm for 15 minutes, and then sintering it at a temperature of 600° C. for 10 hours under an oxygen atmosphere. After naturally cooling to room temperature, the material was taken out and sieved to obtain a second sintered material;

[0086] (3) CoOOH, LiOH and the second sintered material of step (2) were mixed in a high-speed mixer at a speed of 600 rpm for 15 minutes, and then sintered at a temperature of 400° C. for 5 hours under an oxygen atmosphere. The discharged material was cooled to room temperature and sieved to obtain the lithium nickel cobalt aluminum oxide positive electrode material;

[0087] Based on the mass of the second sintered material, the amount of CoOOH added was 6000 ppm, and the amount of LiOH added was 4000 ppm.

[0088] Comparative Example 3

[0089] This comparative example provides a method for preparing a lithium nickel cobalt aluminum oxide positive electrode material. The preparation method is the same as Example 1 except that LiOH is not added in step (3).

[0090] Comparative Example 4

[0091] This comparative example provides a method for preparing a lithium nickel cobalt aluminum oxide positive electrode material. The preparation method is the same as Example 1 except that step (2) is not performed and cobalt is not coated.

[0092] Comparative Example 5

[0093] This comparative example provides a method for preparing a lithium nickel cobalt aluminum oxide positive electrode material. The preparation method is the same as Example 1 except that the mass of CoOOH and the like in step (2) is replaced by Ti2O3.

[0094] Comparative Example 6

[0095] This comparative example provides a method for preparing a positive electrode material of lithium nickel cobalt aluminum oxide. 2.72 Except that equal mass is replaced by B2O3, the rest is the same as Example 1.

[0096] The nickel cobalt aluminum oxide positive electrode materials obtained in the above embodiments and comparative examples were assembled and electrochemical performance tested. The specific steps of the button battery production are: drying the positive electrode material, uniformly mixing it with the conductive agent SP and the binder PVDF in a mass ratio of 94:3:3, and then coating it on aluminum foil. After drying, pressing and slicing, the battery is assembled in an argon-protected glove box. The negative electrode is a metal lithium sheet, the diaphragm is a polyethylene (PE) microporous diaphragm, and the electrolyte is LiPF6-EC / DMC (volume ratio of 1:1); the electrochemical performance test conditions of the battery are: capacity test (2.5V-4.25V, 0.2C) and cycle test (3.0V-4.5V, 25°C, 0.5C / 1C).

[0097] The test results are shown in Table 1:

[0098] Table 1

[0099]

[0100]

[0101] From Table 1 we can see that:

[0102] (1) The method of coating lithium cobalt oxide and lithium tungstate of the present invention can effectively change the interface characteristics of the material and improve the material performance; it can be seen from Example 1 and Comparative Example 1 that Comparative Example 1 simultaneously coats CoOOH and WO 2.72Compared with the method of first coating the cobalt source and then coating the tungsten source and the lithium source in the present invention, the W element will be brought in when the CoOOH shallow surface layer is doped, the primary particles will be refined, and the thermal stability of the material will decrease. In addition, the coating temperature is the same, and it is difficult to exert the optimal performance of the Co and W elements. It can be seen from Example 1, Comparative Example 2 and Comparative Example 4 that the present invention only coats lithium cobaltate or only coats lithium tungstate, and the synergistic effect of the two cannot be exerted, and the obtained material performance is not as good as Example 1; It can be seen from Example 1 and Comparative Example 3 that if no lithium salt is added during coating of the present invention, lithium cobaltate and lithium tungstate coating layers cannot be obtained, and the obtained material performance will decrease.

[0103] (2) It can be seen from Example 1 and Examples 5-6 that the present invention specifically chooses to coat cobalt first and then coat tungsten. Compared with other metals, the two can play a synergistic role to ensure the electrochemical properties of the material; it can be seen from Example 1 and Examples 3-5 that the amount of lithium source added when coating tungsten will affect the amount of lithium cobaltate and lithium tungstate generated, thereby affecting the performance of the material; it can be seen from Examples 1 and 6-9 that the present invention first coats cobalt at high temperature and then coats tungsten at low temperature, that is, coating at a specific sintering temperature, which can promote the synergistic effect of lithium cobaltate and lithium tungstate coating, thereby helping to improve the performance of the material.

[0104] In summary, the present invention provides a nickel cobalt aluminum oxide positive electrode material and its preparation method and application. The preparation method forms a fast ion conductor layer by first coating a cobalt source and then coating a tungsten source and a lithium source. At the same time, the cobalt source and the lithium source during the second coating form a lithium cobalt oxide coating layer, thereby reconstructing the layered structure of the positive electrode material surface, thereby generating lithium cobalt oxide and lithium tungstate coating layers on the surface of the lithium nickel cobalt aluminum oxide, improving the interface characteristics of the positive electrode material, and improving the cycle performance of the material while increasing the discharge capacity.

[0105] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a lithium nickel cobalt aluminum oxide positive electrode material, characterized in that: The preparation method comprises the following steps: (1) mixing and sintering a lithium nickel cobalt aluminum oxide first sinter and a cobalt source to obtain a second sinter; (2) Mixing and sintering the tungsten source, the lithium source and the second sintered material of step (1) to obtain the lithium nickel cobalt aluminum oxide positive electrode material.

2. The preparation method according to claim 1, characterized in that The sintering temperature in step (1) is greater than the sintering temperature in step (2); Preferably, the sintering temperature in step (1) is 500-600° C. and the sintering time is 6-10 h; Preferably, the sintering in step (1) is carried out in an oxygen atmosphere.

3. The preparation method according to claim 1 or 2, characterized in that Based on the mass of the lithium nickel cobalt aluminum oxide sintered in step (1), the amount of the cobalt source added in step (1) is 5000-12000ppm; Preferably, the cobalt source in step (1) includes Co3O4 and / or CoOOH.

4. The preparation method according to any one of claims 1 to 3, characterized in that The method for preparing the lithium nickel cobalt aluminum oxide sintered material in step (1) comprises the following steps: Mixing and calcining a high nickel precursor, an aluminum source, a doping source and a lithium salt to obtain the lithium nickel cobalt aluminum oxide sinter; Preferably, the chemical formula of the high nickel precursor is Ni x Co y (OH)2, where 0.9≤x<1, 0<y<0.1; Preferably, the particle size D50 of the high nickel precursor is 10-15 μm, and the BET is 1-4 μm. 2 / g.

5. The preparation method according to claim 4, characterized in that The doping source includes a zirconium source and / or a magnesium source; Preferably, the doping amount of the doping source is 0.01-0.03 wt% of the lithium nickel cobalt aluminum oxide sinter; Preferably, the calcination temperature is 700-1000° C., the calcination time is 8-12 hours, and the atmosphere is an oxygen atmosphere.

6. The preparation method according to any one of claims 1 to 5, characterized in that Based on the mass of the second sintered material in step (2), the amount of tungsten source added in step (2) is 1000-2000ppm; Preferably, based on the mass of the second sintered material in step (2), the amount of the lithium source added in step (2) is 1000-4000 ppm, preferably 3000-4000 ppm; Preferably, the tungsten source in step (2) comprises WO 2.72 , WO3 or tungstic acid, or a combination of at least two thereof.

7. The preparation method according to any one of claims 1 to 6, characterized in that The sintering temperature in step (2) is 200-400° C. and the sintering time is 3-6 hours; Preferably, the sintering atmosphere in step (2) is an oxygen atmosphere.

8. The preparation method according to any one of claims 1 to 7, characterized in that The preparation method comprises the following steps: (1) mixing a high nickel precursor, an aluminum source, a doping source and a lithium salt, and then calcining at a temperature of 700-1000° C. for 8-12 hours in an oxygen atmosphere to obtain the lithium nickel cobalt aluminum oxide sinter; The general chemical formula of the high nickel precursor is Ni x Co y (OH)2, where 0.9≤x<1, 0<y<0.1, the particle size D50 of the high nickel precursor is 10-15μm, and the BET is 1-4m 2 / g, the doping amount of the doping source is 0.01-0.03wt% of the lithium nickel cobalt aluminum oxide sinter; (2) mixing the cobalt source and the lithium nickel cobalt aluminum oxide first sinter described in step (1), and then sintering at a temperature of 500-600° C. for 6-10 hours in an oxygen atmosphere to obtain a second sinter; Based on the mass of the lithium nickel cobalt aluminum oxide sinter, the amount of the cobalt source added is 5000-12000ppm; (3) mixing a tungsten source, a lithium source and the second sintered material of step (2), and then sintering at a temperature of 200-400° C. for 3-6 hours in an oxygen atmosphere to obtain the lithium nickel cobalt aluminum oxide positive electrode material; Based on the mass of the second-sintered material, the added amount of the tungsten source is 1000-2000 ppm, and the added amount of the lithium source is 3000-4000 ppm.

9. A lithium nickel cobalt aluminum oxide positive electrode material, characterized in that: The lithium nickel cobalt aluminum oxide positive electrode material is prepared by the preparation method according to any one of claims 1 to 8.

10. A lithium ion battery, characterized in that: The lithium-ion battery comprises the lithium nickel cobalt aluminum oxide positive electrode material as claimed in claim 9.

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