Halogen-doped nickel-cobalt lithium aluminate, and preparation method and application thereof

Abstract

The present disclosure relates to a halogen-doped nickel-cobalt-lithium aluminate, a preparation method and application thereof, the method comprising the following steps: S1, mixing nickel hydroxide with an aluminum source in a first solid phase to obtain a first solid material; S2, mixing the first solid material with a cobalt source in a second solid phase, and performing a first heat treatment on the obtained mixture in a first oxygen-containing atmosphere to obtain a second solid material; S3, mixing the second solid material with a lithium source in a third solid phase, and performing a second heat treatment on the obtained mixture in a second oxygen-containing atmosphere; the cobalt source and / or the aluminum source contain halogen. The method has simple steps, is conducive to industrial scale-up implementation and batch production, and the prepared halogen-doped nickel-cobalt-lithium aluminate has relatively uniform mixing of elements; when used as a positive electrode material of a lithium ion battery, the halogen-doped nickel-cobalt-lithium aluminate has a high specific capacity and good cycle performance.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of lithium ion battery ternary material preparation, in particular, to a halogen-doped lithium nickel cobalt aluminate and a preparation method and application thereof. BACKGROUND

[0002] Lithium nickel cobalt aluminate (NCA) is one of the most representative lithium battery ternary positive electrode materials, which has been widely used in the field of new energy vehicles. However, there are still some challenges in its preparation process. The traditional coprecipitation preparation method is difficult to achieve uniform dispersion of aluminum atoms, and is prone to cause poor sphericity and loose structure, thereby affecting the electrochemical performance of the product. Therefore, improving the preparation process of NCA to achieve uniform dispersion of the three elements is expected to improve the electrochemical performance of the material, which has strong practical value.

[0003] With the increase of nickel content, the discharge specific capacity of NCA increases, but Ni 2+ and Li + occur more serious dislocation phenomenon (both have similar ionic radius), which leads to obvious deterioration of cycle performance and thermal stability. In order to reduce ion mixing, the effective method is bulk ion doping. Bulk ion doping can stabilize the layered structure, reduce the degree of cation mixing, and improve the structural stability of the material. Among them, halogen atom doping can partially replace O 2- , change the valence state of transition metal ions, and thus change the lattice structure parameters. At present, the introduction of halogen atoms is mostly by adding halogen-containing compounds during lithiation calcination, but this method is easy to cause halogen atoms to gather on the surface of the particles, and it is difficult to achieve effective doping of them in the crystal lattice. SUMMARY

[0004] The purpose of the present disclosure is to provide a halogen-doped lithium nickel cobalt aluminate and a preparation method and application thereof. In order to achieve the above purpose, the first aspect of the present disclosure provides a method for preparing a halogen-doped lithium nickel cobalt aluminate, which comprises the following steps:

[0005] S1, mixing nickel hydroxide with an aluminum source to obtain a first solid material;

[0006] S2, mixing the first solid material with a cobalt source, and performing first heat treatment on the obtained mixture in a first oxygen-containing atmosphere to obtain a second solid material;

[0007] S3, mixing the second solid material with a lithium source, and performing second heat treatment on the obtained mixture in a second oxygen-containing atmosphere;

[0008] The cobalt source and / or the aluminum source contains halogen.

[0009] Optionally, the aluminum source comprises one or more of aluminum hydroxide, aluminum oxide, aluminum carbonate, aluminum oxalate, aluminum acetate, aluminum fluoride, aluminum chloride, aluminum bromide and aluminum iodide.

[0010] The cobalt source comprises one or more of cobalt hydroxide, cobalt oxide, cobalt carbonate, cobalt oxalate, cobalt acetate, cobalt fluoride, cobalt chloride, cobalt bromide and cobalt iodide.

[0011] The lithium source comprises one or more of lithium hydroxide, lithium carbonate and lithium nitrate.

[0012] Optionally, the first solid-phase mixing, the second solid-phase mixing and the third solid-phase mixing are performed by solid-phase ball milling for 1-5 hours.

[0013] Optionally, in the step S2, the first heat treatment is performed by calcination, and the first heat treatment is performed at a temperature of 400-900℃ for 2-8 hours.

[0014] Optionally, in the step S3, the second heat treatment is performed by calcination, and the second heat treatment is performed at a temperature of 600-850℃ for 10-20 hours.

[0015] Optionally, the average particle size of the nickel hydroxide is 5-15 μm.

[0016] Optionally, the first oxygen-containing atmosphere and the second oxygen-containing atmosphere are oxygen atmosphere or air atmosphere.

[0017] The second aspect of the present disclosure provides a halogen-doped lithium nickel cobalt aluminate prepared by the method of the first aspect of the present disclosure.

[0018] Optionally, the halogen-doped lithium nickel cobalt aluminate comprises particles of the chemical formula LiNi 1-x-y Co x Al y O 2-0.5z X z , 0.6≤1-x-y<1, 0

[0019] The third aspect of the present disclosure provides a lithium ion battery, which comprises a positive electrode, an electrolyte and a negative electrode, wherein the positive electrode comprises the halogen-doped lithium nickel cobalt aluminate of the second aspect of the present disclosure.

[0020] By the technical scheme, the nickel-cobalt lithium aluminate doped with halogen is obtained by controlling the sequence of mixing and heat treatment of each metal source and introducing halogen by metal halide through the method of step-by-step mixing combined with multi-step heat treatment. The method of the present disclosure is simple in steps, is conducive to industrial scale-up implementation and batch production, and the prepared nickel-cobalt lithium aluminate doped with halogen is relatively uniform in mixed phase of each element, and at least part of the halogen can be doped into the crystal lattice; when used as a positive electrode material of a lithium ion battery, the nickel-cobalt lithium aluminate doped with halogen has high specific capacity and good cycle performance.

[0021] Other features and advantages of the present disclosure will be described in detail in the following specific embodiments section. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings are included to provide a further understanding of the present disclosure and constitute a part of the specification, and together with the following specific embodiments, serve to explain the present disclosure but do not constitute a limitation on the present disclosure. In the drawings:

[0023] Figure 1 Electrochemical cycle curves of the nickel-cobalt lithium aluminates A1, D1 and D2 prepared in Example 1 and Comparative Examples 1-2 of the present disclosure.

[0024] Figure 2 X-ray diffraction patterns of the nickel-cobalt lithium aluminates A1, D1 and D2 prepared in Example 1 and Comparative Examples 1-2 of the present disclosure.

[0025] Figure 3 Scanning electron microscope images and element distribution maps of the F-doped nickel-cobalt lithium aluminate A1 prepared in Example 1 of the present disclosure.

[0026] Figure 4 Scanning electron microscope images and element distribution maps of the F-doped nickel-cobalt lithium aluminate D2 prepared in Comparative Example 2 of the present disclosure. DETAILED DESCRIPTION

[0027] The specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0028] The first aspect of the present disclosure provides a method for preparing a nickel-cobalt lithium aluminate doped with halogen, which comprises the following steps:

[0029] S1, mixing nickel hydroxide with an aluminum source to obtain a first solid material;

[0030] S2, mixing the first solid material with a cobalt source to obtain a mixture, and performing first heat treatment on the mixture in a first oxygen-containing atmosphere to obtain a second solid material;

[0031] S3, mixing the second solid material with a lithium source to form a third mixture, and performing a second heat treatment on the third mixture in a second oxygen-containing atmosphere;

[0032] The cobalt source and / or the aluminum source contains halogen.

[0033] The present application adopts a method of step-by-step mixing combined with multi-step heat treatment, and prepares halogen-doped lithium nickel cobalt aluminate by controlling the order of mixing and heat treatment of each metal source and introducing halogen through metal halide. The method of the present disclosure utilizes the migration of cobalt atoms to drive the migration of other atoms, which can not only realize the proportion regulation and uniform mixing of each element, but also realize the effective doping of halogen atoms and broaden the source thereof. The halogen-doped lithium nickel cobalt aluminate prepared has a relatively uniform mixed phase of each element, at least part of the halogen can be doped into the bulk phase of the material, and can be doped into the crystal lattice. When used as a positive electrode material of a lithium ion battery, it has a high specific capacity and good cycle performance.

[0034] According to an embodiment of the present disclosure, the halogen includes one or more of fluorine, chlorine, bromine and iodine.

[0035] According to an embodiment of the present disclosure, the nickel hydroxide has a spherical and / or spheroid morphology, and the spherical and spheroid morphology are both conventional definitions in the art. Preferably, the average particle size of the nickel hydroxide is 5-15 μm.

[0036] According to an embodiment of the present disclosure, in order to mix uniformly, the first, second and third solid-phase mixing methods include solid-phase ball milling for 1-5 h, preferably 2-4 h. The solid-phase ball milling can be performed, for example, on a planetary ball mill.

[0037] According to an embodiment of the present disclosure, the types of the aluminum source, the cobalt source and the lithium source are conventional in the art. For example, the aluminum source includes one or more of aluminum hydroxide, aluminum oxide, aluminum carbonate, aluminum oxalate, aluminum acetate, aluminum fluoride, aluminum chloride, aluminum bromide and aluminum iodide. When the aluminum source includes two or more substances, the proportion thereof is not specifically limited. The cobalt source includes one or more of cobalt hydroxide, cobalt oxide, cobalt carbonate, cobalt oxalate, cobalt acetate, cobalt fluoride, cobalt chloride, cobalt bromide and cobalt iodide. When the cobalt source includes two or more substances, the proportion thereof is not specifically limited. The lithium source includes one or more of lithium hydroxide, lithium carbonate and lithium nitrate. When the lithium source includes two or more substances, the proportion thereof is not specifically limited.

[0038] In the present disclosure, the lithium source does not contain halogen.

[0039] According to an embodiment of the present disclosure, in step S2, the first heat treatment is performed by calcination, and the conditions of the first heat treatment are as follows: the time is 2-8h, and the temperature is 400-900℃; preferably, the time is 3-7h, and the temperature is 500-800℃; under the conditions, the migration of metal ions is achieved, and the uniform dispersion of elements is promoted.

[0040] According to an embodiment of the present disclosure, in step S3, the second heat treatment is performed by calcination, and the conditions of the second heat treatment are as follows: the time is 10-20h, and the temperature is 600-850℃; preferably, the time is 12-18h, and the temperature is 700-800℃; under the conditions, the diffusion of Li is better, and a higher material capacity is achieved.

[0041] According to an embodiment of the present disclosure, the first oxygen-containing atmosphere and the second oxygen-containing atmosphere are oxygen atmosphere or air atmosphere, wherein the oxygen-containing atmosphere and the air atmosphere are defined as conventional in the art.

[0042] In the present disclosure, the calcination is performed by conventional methods in the art, for example, in a saggar.

[0043] In the present disclosure, part of the halogen may be lost during preparation.

[0044] In the present disclosure, the amounts of the nickel hydroxide, the cobalt source and the aluminum source are set according to the molar ratio of nickel element, cobalt element and aluminum element in the product.

[0045] According to an embodiment of the present disclosure, the molar ratio of the lithium source (calculated as lithium element) to the second solid material (calculated as the total amount of nickel element, cobalt element and aluminum element) is (0.8-1.2):1, preferably (0.95-1.15):1; part of the lithium source may be lost during ball milling and heat treatment.

[0046] The second aspect of the present disclosure provides a halogen-doped lithium nickel cobalt aluminate prepared by the method of the first aspect of the present disclosure.

[0047] According to an embodiment of the present disclosure, the halogen-doped lithium nickel cobalt aluminate comprises particles of the chemical formula LiNi 1-x- y Co x Al y O 2-0.5z X z , 0.6≤1-x-y<1, 0

[0048] The third aspect of the present disclosure provides a lithium ion battery, which comprises a positive electrode, an electrolyte and a negative electrode, wherein the positive electrode comprises the halogen-doped lithium nickel cobalt aluminate of the second aspect of the present disclosure.

[0049] According to an embodiment of the present disclosure, the negative electrode is conventional in the art, and can comprise one or more of lithium sheet, carbon material and silicon-carbon composite material.

[0050] According to an embodiment of the present disclosure, the electrolyte is conventional in the art, and can comprise one or more of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, lithium hexafluorophosphate and dimethyl carbonate.

[0051] The present disclosure will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art further understand the present disclosure, but do not limit the present disclosure in any form.

[0052] The raw materials used in the examples were obtained by commercial purchase, and were all analytical pure if not specifically stated.

[0053] The testing instrument of scanning electron microscope (SEM) was FEI QUANTA 400, and the method was accelerating voltage of 20 kV.

[0054] The testing instrument of X-ray diffraction (XRD) was X-ray powder diffractometer of American Philips Company, and the method was using Cu target anode Kα radiation source, step width of 0.02°, scanning speed of 2° / min, 2θ=10°-80°.

[0055] The testing instrument of X-ray photoelectron spectroscopy (XPS) was ESCALAB 250.

[0056] The testing method of chemical formula of the positive electrode material was inductively coupled plasma mass spectrometer.

[0057] Example 1

[0058] Fluorine-doped lithium nickel cobalt aluminate A1 was prepared by the following steps:

[0059] (1) 0.9 mol of spherical nickel hydroxide (average particle size of 8.5 μm), 0.02 mol of aluminum hydroxide and 0.01 mol of aluminum fluoride were weighed according to the molar ratio of n(Ni):n(Al)=0.9:0.03, and mixed on a planetary ball mill for 2 h to obtain a first solid material;

[0060] (2) 0.07 mol of cobalt acetate was weighed out according to the molar ratio of n(Ni):n(Co) = 0.9:0.07, and was added to the first solid material. After mixing for 2 h on a planetary ball mill, the obtained mixture was loaded into a crucible, and a first heat treatment was performed under an oxygen atmosphere at a temperature of 700°C for 5 h to obtain a second solid material;

[0061] (3) 1.05 mol of lithium hydroxide and 1 mol of the second solid material were weighed out according to the molar ratio of n(Li):n(Ni+Co+Al) = 1.05:1, respectively, and were mixed on a planetary ball mill for 2 h. The obtained mixture was loaded into a crucible, and a second heat treatment was performed under an oxygen atmosphere at a temperature of 730°C for 15 h. The obtained solid product was crushed and sieved to obtain fluorine-doped lithium nickel cobalt aluminate Al having a chemical formula of LiNi 0.9 Co 0.07 Al 0.03 O 1.9895 F 0.021 , and the parameters are listed in Table 1.

[0062] Example 2

[0063] Chlorine-doped lithium nickel cobalt aluminate A2 was prepared by the following steps:

[0064] (1) 0.8 mol of spherical nickel hydroxide (average particle size of 8.2 μm) and 0.05 mol of aluminum hydroxide powder were weighed out according to the molar ratio of n(Ni):n(Al) = 0.8:0.05, respectively, and were mixed on a planetary ball mill for 2 h to obtain a first solid material;

[0065] (2) 0.135 mol of cobalt acetate and 0.015 mol of cobalt chloride were weighed out according to the molar ratio of n(Ni):n(Co) = 0.8:0.15, and were added to the first solid material. After mixing for 2 h on a planetary ball mill, the obtained mixture was loaded into a crucible, and a first heat treatment was performed under an oxygen atmosphere at a temperature of 600°C for 6 h to obtain a second solid material;

[0066] (3) 1.05 mol of lithium hydroxide and 1 mol of the second solid material were weighed out according to the molar ratio of n(Li):n(Ni+Co+Al) = 1.05:1, respectively, and were mixed on a planetary ball mill for 3 h. The obtained mixture was loaded into a crucible, and a second heat treatment was performed under an oxygen atmosphere at a temperature of 750°C for 18 h. The obtained solid product was crushed and sieved to obtain chlorine-doped lithium nickel cobalt aluminate A2 having a chemical formula of LiNi 0.8 Co 0.15 Al 0.05 O 1.992 Cl 0.016 .

[0067] Example 3

[0068] Bromine-doped nickel cobalt lithium aluminate cathode material A3 was prepared by the following steps:

[0069] (1) 0.89 mol of spherical nickel hydroxide (average particle size of 8.5 μm) and 0.03 mol of aluminum oxide powder were weighed according to the molar ratio of n(Ni):n(Al)=0.89:0.03, and mixed on a planetary ball mill for 2 h to obtain a first solid material;

[0070] (2) 0.07 mol of cobalt carbonate and 0.01 mol of cobalt bromide were weighed according to the molar ratio of n(Ni):n(Co)=0.89:0.08, and added to the first solid material. After mixing on a planetary ball mill for 2 h, the obtained mixture was loaded into a crucible, and a first heat treatment was carried out under an oxygen atmosphere at a temperature of 700°C for 5 h to obtain a second solid material;

[0071] (3) 1.06 mol of lithium hydroxide and 1 mol of the second solid material were weighed according to the molar ratio of n(Li):n(Ni+Co+Al)=1.06:1, and mixed on a planetary ball mill for 3 h. The obtained mixture was loaded into a crucible, and a second heat treatment was carried out under an oxygen atmosphere at a temperature of 710°C for 18 h. The obtained solid product was crushed and sieved to obtain bromine-doped nickel cobalt lithium aluminate A3, with a chemical formula of LiNi 0.89 Co 0.08 Al 0.03 O 1.9951 Br 0.0098 .

[0072] Example 4

[0073] Iodine-doped nickel cobalt lithium aluminate A4 was prepared by the following steps:

[0074] (1) 0.92 mol of spherical nickel hydroxide (average particle size of 8.5 μm), 0.02 mol of aluminum hydroxide, and 0.01 mol of aluminum iodide were weighed according to the molar ratio of n(Ni):n(Al)=0.92:0.03, and mixed on a planetary ball mill for 2 h to obtain a first solid material;

[0075] (2) 0.05 mol of cobalt acetate was weighed according to the molar ratio of n(Ni):n(Co)=0.92:0.05, and added to the first solid material. After mixing on a planetary ball mill for 2 h, the obtained mixture was loaded into a crucible, and a first heat treatment was carried out under an oxygen atmosphere at a temperature of 800°C for 6 h to obtain a second solid material;

[0076] (3) 1.08 mol of lithium hydroxide and 1 mol of the second solid material were weighed out according to a molar ratio of n(Li):n(Ni+Co+Al) = 1.08:1, mixed in a planetary ball mill for 3 h, and the obtained mixture was loaded into a crucible, and a second heat treatment was performed under an oxygen atmosphere at a temperature of 720°C for 18 h. The obtained solid product was crushed and sieved to obtain iodine-doped lithium nickel cobalt aluminate A4 with a chemical formula of LiNi 0.92 Co 0.05 Al 0.03 O 1.994 I 0.012 .

[0077] Comparative Example 1

[0078] Fluorine-doped lithium nickel cobalt aluminate D1 was prepared by the following steps:

[0079] (1) 0.9 mol of spherical nickel hydroxide (average particle size of 8.5 μm) and 0.03 mol of aluminum hydroxide were weighed out according to a molar ratio of n(Ni):n(Al) = 0.9:0.03, mixed in a planetary ball mill for 2 h, and a first solid material was obtained;

[0080] (2) 0.07 mol of cobalt acetate and 0.03 mol of ammonium fluoride were weighed out according to a molar ratio of n(Ni):n(Co) = 0.9:0.07, added to the first solid material, mixed in a planetary ball mill for 2 h, and the obtained mixture was loaded into a crucible, and a first heat treatment was performed under an oxygen atmosphere at a temperature of 700°C for 5 h to obtain a second solid material;

[0081] (3) 1.05 mol of lithium hydroxide and 1 mol of the second solid material were weighed out according to a molar ratio of n(Li):n(Ni+Co+Al) = 1.05:1, mixed in a planetary ball mill for 2 h, and the obtained mixture was loaded into a crucible, and a second heat treatment was performed under an oxygen atmosphere at a temperature of 730°C for 15 h. The obtained solid product was crushed and sieved to obtain fluorine-doped lithium nickel cobalt aluminate cathode material D1 with a chemical formula of LiNi 0.9 Co 0.07 Al 0.03 O 1.992 F 0.016 , and the parameters are listed in Table 1.

[0082] Comparative Example 2

[0083] Fluorine-doped lithium nickel cobalt aluminate D2 was prepared by the following steps:

[0084] (1) 0.9 mol of spherical nickel hydroxide (average particle size of 8.5 μm) and 0.03 mol of aluminum hydroxide were weighed according to the molar ratio of n(Ni):n(Al) = 0.9:0.03, and mixed on a planetary ball mill for 2 h to obtain a first solid material;

[0085] (2) 0.07 mol of cobalt acetate was weighed according to the molar ratio of n(Ni):n(Co) = 0.9:0.07, and added to the first solid material. After mixing on a planetary ball mill for 2 h, the obtained mixture was loaded into a crucible, and a first heat treatment was performed under an oxygen atmosphere at a temperature of 700°C for 5 h to obtain a second solid material;

[0086] (3) 1.02 mol of lithium hydroxide, 0.03 mol of lithium fluoride, and 1 mol of the second solid material were weighed according to the molar ratio of n(Li):n(Ni+Co+Al) = 1.05:1, and mixed on a planetary ball mill for 2 h. The obtained mixture was loaded into a crucible, and a second heat treatment was performed under an oxygen atmosphere at a temperature of 730°C for 15 h. The obtained solid product was crushed and sieved to obtain fluorine-doped lithium nickel cobalt aluminate D2, with a chemical formula of LiNi 0.9 Co 0.07 Al 0.03 O 1.989 F 0.022 , and the parameters are listed in Table 1.

[0087] Table 1

[0088] Material No. Cell parameter c (nm) Atomic ratio of surface F element (%) Example 1 A1 1.42275 1.64 Comparative Example 1 D1 1.42263 1.96 Comparative Example 2 D2 1.42269 2.53

[0089] The cell parameters in Table 1 were tested by XRD, and the atomic ratio of surface F elements refers to the proportion of F atoms on the surface of the particles to all atoms on the surface, which was tested by XPS.

[0090] According to the data in Table 1, the cell parameters of the halogen-doped lithium nickel cobalt aluminate A1 prepared by the method of the present disclosure are larger than those of D1-D2, which is beneficial to the transmission of lithium ions; and the atomic ratio of surface F elements of A1 is lower than that of D1-D2 under the same F dosage, indicating that the F elements are doped into the material.

[0091] A1, D1, and D2 were subjected to XRD testing, and the results are shown in Figure 2 .

[0092] According to Figure 2 , under the same F dosage, the peak position of A1 is shifted to a larger degree compared with the materials D1 and D2 doped with halogen by ammonium fluoride and the surface halogen-doped material D2, indicating that the F elements are doped to a larger degree, and at least part of the halogen is doped into the crystal lattice of the material.

[0093] The sample A1 and D2 were subjected to scanning electron microscopy (SEM) test to analyze the element distribution of the sample, and the results are shown in Figure 3 and Figure 4 .

[0094] According to Figure 3 and Figure 4 , the four elements of Ni, Co, Al and F in A1 are uniformly dispersed relative to D2, indicating that the elements in the halogen-doped lithium nickel cobalt aluminate prepared by the method of the present disclosure are uniformly distributed.

[0095] Test Example

[0096] The lithium nickel cobalt aluminate A1 and D1-D2 prepared in the examples and comparative examples were subjected to electrochemical performance test, and the specific steps were as follows:

[0097] The positive electrode material, conductive agent (acetylene black) and binder (polyvinylidene fluoride) were weighed according to a mass ratio of 8:1:1, mixed uniformly with a solvent (N-methyl pyrrolidone), coated on an aluminum foil and cut into sheets as a positive electrode; and then combined with lithium sheets, electrolyte (1 mol·L -1 LiPF6 solution in ethylene carbonate / methyl ethyl carbonate / dimethyl carbonate with a mass ratio of 1:1:1) and a separator (Celgard 2300) to form a lithium ion half-cell, and the electrochemical performance test was carried out, and the results are shown in Figure 1 .

[0098] The specific test conditions were as follows: the charge and discharge voltage range was 2.75-4.3V; the charge and discharge rate was 0.1C for the first 4 times and 0.5C after the 5th time, and the test temperature was 35℃.

[0099] According to Figure 1 , after 200 cycles, the discharge specific capacity of the sample D1 with ammonium fluoride introduced in the pre-burning stage was 148.3mAh / g, and the capacity retention rate was 76.44%; the discharge specific capacity of the sample D2 with LiF introduced in the lithiation stage was 153.6mAh / g, and the capacity retention rate was 80.74%; and the discharge specific capacity of the fluorine-doped lithium nickel cobalt aluminate A1 prepared by the method of the present disclosure was 165.0mAh / g, and the capacity retention rate was 86.04%.

[0100] According to the above data, the elements in the halogen-doped lithium nickel cobalt aluminate prepared by the method of the present disclosure are relatively uniformly mixed, and at least part of the halogen can be doped into the crystal lattice; when used as a positive electrode material for lithium ion batteries, it has a high specific capacity and good cycle performance.

[0101] The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, but the present disclosure is not limited to the specific details in the above-described embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

[0102] In addition, it should be noted that each specific technical feature described in the above-described specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again in the present disclosure.

[0103] In addition, various different embodiments of the present disclosure can also be combined in any appropriate manner, as long as they do not deviate from the idea of the present disclosure, and they should also be considered as disclosed by the present disclosure.

Claims

1. A method for preparing halogen-doped lithium nickel cobalt aluminum oxide, characterized in that, The method includes the following steps: S1. Nickel hydroxide and aluminum source are mixed in a first solid phase to obtain a first solid material; S2. The first solid material is mixed with a cobalt source in a second solid phase, and the resulting mixture is subjected to a first heat treatment under a first oxygen-containing atmosphere to obtain a second solid material. S3. The second solid material is mixed with the lithium source in a third solid phase, and the resulting mixture is subjected to a second heat treatment in a second oxygen-containing atmosphere. The cobalt source and / or the aluminum source contain halogens; The methods of the first solid-phase mixing, the second solid-phase mixing, and the third solid-phase mixing include solid-phase ball milling.

2. The method according to claim 1, wherein, The aluminum source includes one or more of aluminum hydroxide, aluminum oxide, aluminum carbonate, aluminum oxalate, aluminum acetate, aluminum fluoride, aluminum chloride, aluminum bromide, and aluminum iodide. The cobalt source includes one or more of cobalt hydroxide, cobalt oxide, cobalt carbonate, cobalt oxalate, cobalt acetate, cobalt fluoride, cobalt chloride, cobalt bromide, and cobalt iodide. The lithium source includes one or more of lithium hydroxide, lithium carbonate, and lithium nitrate.

3. The method according to claim 1, wherein, The mixing times for the first solid phase, the second solid phase, and the third solid phase are 1-5 hours, respectively.

4. The method according to claim 1, wherein, In step S2, the first heat treatment method includes calcination, and the conditions of the first heat treatment include: a time of 2-8 hours and a temperature of 400-900℃.

5. The method according to claim 1, wherein, In step S3, the second heat treatment method includes calcination, and the conditions of the second heat treatment include: a time of 10-20 hours and a temperature of 600-850°C.

6. The method according to claim 1, wherein, The average particle size of the nickel hydroxide is 5-15 μm.

7. The method according to claim 1, wherein, The first oxygen-containing atmosphere and the second oxygen-containing atmosphere are respectively an oxygen atmosphere or an air atmosphere.

8. Halogen-doped lithium nickel cobalt aluminum oxide prepared by the method according to any one of claims 1-7.

9. The halogen-doped lithium nickel cobalt aluminum oxide according to claim 8, wherein, The halogen-doped lithium nickel cobalt aluminate includes particles with the chemical formula LiNi 1-x-y Co x Al y O 2-0.5z X z , where 0.6 ≤ 1 - x - y < 1, 0 < x ≤ 0.2, 0 < y ≤ 0.2, 0 < z ≤ 0.1, and X is one or more of F, Cl, Br, and I.

10. A lithium-ion battery, the lithium-ion battery comprising a positive electrode, an electrolyte, and a negative electrode, characterized in that, The positive electrode comprises the halogen-doped lithium nickel cobalt aluminum oxide as described in claim 8 or 9.

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