A halogen-doped quaternary positive electrode material, a preparation method and application thereof

Abstract

The present disclosure relates to a halogen-doped quaternary positive electrode material and a preparation method and application thereof, the method comprising the following steps: S1, mixing nickel hydroxide, an aluminum source and a manganese source by a first solid phase mixing to obtain a first solid material; S2, mixing the first solid material with a cobalt source by a second solid phase mixing, and performing a first heat treatment on the obtained mixed material under a first oxygen-containing atmosphere to obtain a second solid material; S3, mixing the second solid material with a lithium source by a third solid phase mixing, and performing a second heat treatment on the obtained mixed material under a second oxygen-containing atmosphere; at least one of the cobalt source, the manganese source and the aluminum source contains halogen; the method of the present disclosure is simple in steps, the element distribution in the halogen-doped quaternary material prepared is uniform, and the halogen element can play a uniform bulk doping effect, so that the halogen-doped quaternary material has high electrochemical cycle performance and rate performance as a battery positive electrode material.

Description

TECHNICAL FIELD

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

[0002] Increasing the proportion of nickel in ternary lithium batteries can improve the energy density of the battery. However, when the nickel content exceeds 90% (i.e. super-high nickel battery), the thermal stability of the battery will decrease rapidly, and the capacity retention rate will also begin to decrease. That is, the safety is reduced and the battery is more prone to degradation. NCMA battery is based on NCM super-high nickel battery and incorporates 1% aluminum element. Studies have shown that compared with NCA material, the battery performance of NCMA has been greatly improved. However, there are still certain technical difficulties in achieving uniform dispersion of aluminum elements.

[0003] In addition, bulk ion doping can further stabilize the layered structure and reduce the degree of cation mixing, thereby improving the structural stability of high-nickel materials. Studies have shown that halogen atom doping can partially replace O 2- , change the valence state of transition metal ions, and thus change the lattice structure parameters, which also has a certain influence on the electrochemical performance. However, current halogen doping is mainly surface doping of ternary materials, and there are few reports on bulk doping and halogen doping of quaternary materials. SUMMARY

[0004] The purpose of the present disclosure is to provide a halogen-doped quaternary cathode material and a preparation method and application thereof.

[0005] To achieve the above purpose, the first aspect of the present disclosure provides a method for preparing a halogen-doped quaternary cathode material, the method comprising the following steps:

[0006] S1, mixing nickel hydroxide, an aluminum source and a manganese source by a first solid phase to obtain a first solid material;

[0007] S2, mixing the first solid material with a cobalt source by 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;

[0008] S3, mixing the second solid material with a lithium source by a third solid phase, and performing a second heat treatment on the obtained mixture in a second oxygen-containing atmosphere;

[0009] At least one of the cobalt source, the manganese source and the aluminum source contains halogen.

[0010] Optionally, 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;

[0011] The manganese source includes one or more of manganese hydroxide, manganese dioxide, trimanganese tetraoxide, manganese carbonate, manganese oxalate, manganese acetate, manganese fluoride, manganese chloride, manganese bromide, and manganese iodide.

[0012] 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.

[0013] The lithium source includes one or more of lithium hydroxide, lithium carbonate, and lithium nitrate.

[0014] Optionally, the manner of the first solid-phase mixing, the second solid-phase mixing, and the third solid-phase mixing includes solid-phase ball milling, and the time is 1-5h, respectively.

[0015] Optionally, in the step S2, the manner of the first heat treatment includes calcination, and the condition of the first heat treatment includes that the time is 2-8h and the temperature is 400-900℃.

[0016] Optionally, in the step S3, the manner of the second heat treatment includes calcination, and the condition of the second heat treatment includes that the time is 10-20h and the temperature is 600-850℃.

[0017] Optionally, the average particle size of the nickel hydroxide is 5-15μm.

[0018] Optionally, the first oxygen-containing atmosphere and the second oxygen-containing atmosphere are oxygen atmosphere or air atmosphere, respectively.

[0019] The second aspect of the present disclosure provides a halogen-doped quaternary cathode material prepared by the method of the first aspect of the present disclosure.

[0020] The third aspect of the present disclosure provides a halogen-doped quaternary cathode material, the chemical formula of which is LiNi 1-x-y-z Co x Mn y Al z O 2-0.5p X p , 0.6≤1-x-y-z<1, 0<x≤0.15, 0<y≤0.15, 0<z≤0.1, 0<p≤0.1, and X is one or more of F, Cl, Br, and I.

[0021] The fourth aspect of the present disclosure provides a lithium ion battery, which includes a cathode, an electrolyte, and an anode, and the cathode includes the halogen-doped quaternary cathode material of the second aspect or the third aspect of the present disclosure.

[0022] By the technical scheme, the method of step-by-step mixing combined with multi-step heat treatment is adopted, the sequence of mixing and heat treatment of each metal source is controlled, and halogen is introduced by metal halide, so that the halogen-doped quaternary positive electrode material is obtained, the element distribution of which is uniform, and at least part of the halogen elements can be doped into the material body phase and into the crystal lattice, which not only can increase the material structure stability and improve the electrochemical cycle performance, but also can increase the cell parameter and promote the transmission of lithium ions, thereby improving the rate performance.

[0023] Other features and advantages of the present disclosure will be described in detail in the following specific embodiments section. BRIEF DESCRIPTION OF DRAWINGS

[0024] The accompanying drawings are included to provide a further understanding of the present disclosure and constitute a part of the specification, and are used together with the following specific embodiments to explain the present disclosure, but do not constitute a limitation on the present disclosure. In the drawings:

[0025] Figure 1 Electrochemical rate curve diagram of quaternary positive electrode materials A1, A2, D1 and D2 prepared in embodiments 1-2 and comparative examples 1-2 of the present application.

[0026] Figure 2 Electrochemical cycle curve diagram and capacity retention rate diagram after 150 cycles of quaternary positive electrode materials A1, A2, D1 and D2 prepared in embodiments 1-2 and comparative examples 1-2 of the present application.

[0027] Figure 3 X-ray diffraction diagram of quaternary positive electrode materials A1, A2, D1 and D2 prepared in embodiments 1-2 and comparative examples 1-2 of the present application.

[0028] Figure 4 Scanning electron microscope and element distribution diagram of Cl-doped quaternary positive electrode material A1 prepared in embodiment 1 of the present application.

[0029] Figure 5 Scanning electron microscope and element distribution diagram of Cl-doped quaternary positive electrode material D2 prepared in comparative example 2 of the present application. DETAILED DESCRIPTION

[0030] The specific embodiments of the present disclosure will be 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.

[0031] The first aspect of the present disclosure provides a method for preparing a halogen-doped quaternary positive electrode material, which comprises the following steps:

[0032] S1, mixing nickel hydroxide, an aluminum source and a manganese source by a first solid phase to obtain a first solid material;

[0033] S2, second solid-phase mixing the first solid material with a cobalt source, and first heat treatment of the obtained mixed material in a first oxygen-containing atmosphere to obtain a second solid material;

[0034] S3, third solid-phase mixing the second solid material with a lithium source, and second heat treatment of the obtained mixed material in a second oxygen-containing atmosphere;

[0035] At least one of the cobalt source, the manganese source and the aluminum source contains halogen.

[0036] The present disclosure adopts a method of step-by-step mixing combined with multi-step heat treatment, prepares halogen-doped quaternary materials by controlling the order of mixing and heat treatment of each metal source and introducing halogen through metal halide, wherein each element is relatively uniformly mixed, at least part of the halogen can be doped into the bulk phase of the material, and into the crystal lattice; and the material is used as a positive electrode material of a lithium ion battery, and has good cycle performance and rate performance.

[0037] In the present disclosure, "at least one of the cobalt source, the manganese source and the aluminum source contains halogen" means that one, two or three of the cobalt source, the manganese source and the aluminum source contain halogen; the halogen includes one or more of fluorine element, chlorine element, bromine element and iodine element.

[0038] 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.

[0039] According to an embodiment of the present disclosure, in order to mix uniformly, 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 h, preferably 2-4 h; the solid-phase ball milling can be performed, for example, on a planetary ball mill.

[0040] According to one embodiment of the present disclosure, the types of the manganese source, 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 proportions thereof are 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 proportions thereof are not specifically limited; the manganese source includes one or more of manganese hydroxide, manganese dioxide, trimanganese tetroxide, manganese carbonate, manganese oxalate, manganese acetate, manganese fluoride, manganese chloride, manganese bromide and manganese iodide, when the manganese source includes two or more substances, the proportions thereof are 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 proportions thereof are not specifically limited.

[0041] In the present disclosure, the lithium source does not contain halogen.

[0042] According to one embodiment of the present disclosure, in step S2, the first heat treatment is performed by calcination, and the conditions of the first heat treatment include a time of 2-8h and a temperature of 400-900℃; preferably, a time of 3-7h and a temperature of 500-800℃; the conditions can exert the migration effect of metal ions and promote the uniform mixing of elements.

[0043] According to one embodiment of the present disclosure, in step S3, the second heat treatment is performed by calcination, and the conditions of the second heat treatment include a time of 10-20h and a temperature of 600-850℃; preferably, a time of 12-18h and a temperature of 700-800℃; the conditions are favorable for the diffusion of Li and can obtain higher material capacity.

[0044] According to one embodiment of the present disclosure, the first oxygen-containing atmosphere and the second oxygen-containing atmosphere are oxygen atmosphere or air atmosphere, respectively, wherein the oxygen-containing atmosphere and the air atmosphere are defined conventionally in the art.

[0045] In the present disclosure, the calcination is performed conventionally in the art, for example, in a sagger.

[0046] In the present disclosure, part of the halogen can be lost during the preparation process.

[0047] In the present disclosure, the amounts of the nickel hydroxide, the manganese source, the cobalt source and the aluminum source are set according to the molar ratio of the nickel element, the cobalt element and the aluminum element in the product.

[0048] According to an embodiment of the present disclosure, the molar ratio of the lithium source in terms of lithium element to the second solid material in terms of the total amount of manganese element, nickel element, cobalt element and aluminum element may be, for example, (0.8-1.2):1, preferably (0.95-1.15):1, with part of the lithium source being lost during the ball milling and heat treatment.

[0049] The second aspect of the present disclosure provides a halogen-doped quaternary cathode material prepared by the method of the first aspect of the present disclosure.

[0050] The third aspect of the present disclosure provides a halogen-doped quaternary cathode material, which comprises particles of the chemical formula LiNi 1-x-y-z Co x Mn y Al z O 2-0.5p X p 0.6≤1-x-y-z<1, 0

[0051] According to an embodiment of the present disclosure, 0.8≤1-x-y-z≤0.96, 0.02≤x≤0.10, 0.02≤y≤0.1, 0<z≤0.05.

[0052] The halogen-doped quaternary cathode material of the second aspect of the present disclosure has the same features as the quaternary cathode material of the third aspect of the present disclosure, and will not be described here.

[0053] The fourth aspect of the present disclosure provides a lithium ion battery, which comprises a cathode, an electrolyte and an anode, the cathode comprising the halogen-doped quaternary cathode material of the second aspect or the third aspect of the present disclosure.

[0054] According to an embodiment of the present disclosure, the anode is conventional in the art, and may, for example, comprise one or more of lithium sheet, carbon material and silicon-carbon composite material.

[0055] According to an embodiment of the present disclosure, the electrolyte is conventional in the art, and may, for example, comprise one or more of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, lithium hexafluorophosphate and dimethyl carbonate.

[0056] The present disclosure will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present disclosure, but do not limit the present disclosure in any form.

[0057] The raw materials used in the examples were obtained by commercial purchase, and were all analytical pure unless otherwise specified.

[0058] The testing instrument model of scanning electron microscope SEM is FEI QUANTA 400, and the method is accelerating voltage of 20 kV.

[0059] The testing instrument model of X-ray diffraction diagram XRD is X-ray powder diffractometer of American Philips Company, and the method is using Cu target anode Kα radiation source, step width of 0.02°, scanning speed of 2° / min, and 2θ=10°-80°.

[0060] The testing instrument model of X-ray photoelectron spectroscopy XPS is ESCALAB 250.

[0061] The testing method of chemical formula of positive electrode material is inductively coupled plasma mass spectrometer.

[0062] Example 1

[0063] The following steps are used to prepare the chlorine-doped quaternary positive electrode material A1:

[0064] (1) 0.89 mol of spherical nickel hydroxide (average particle size of 8.5 μm), 0.01 mol of aluminum chloride and 0.05 mol of manganese oxalate are weighed according to the molar ratio of n(Ni):n(Al):n(Mn)=0.89:0.01:0.05, mixed on a planetary ball mill for 2 h to obtain a first solid material;

[0065] (2) 0.05 mol of cobalt acetate is weighed according to the molar ratio of n(Ni):n(Co)=0.89:0.05, and then added to the first solid material. After mixing on a planetary ball mill for 2 h, the obtained mixture is loaded into a crucible, and a first heat treatment is carried out under an oxygen atmosphere, with a temperature of 700°C and a time of 5 h, to obtain a second solid material;

[0066] (3) 1.05 mol of lithium hydroxide and 1 mol of the second solid material are weighed according to the molar ratio of n(Li):n(Ni+Co+Mn+Al)=1.05:1, and then mixed on a planetary ball mill for 2 h. The obtained mixture is loaded into a crucible, and a second heat treatment is carried out under an oxygen atmosphere, with a temperature of 730°C and a time of 15 h. The obtained solid product is crushed and sieved to obtain the chlorine-doped quaternary positive electrode material A1, with a chemical formula of LiNi 0.89 Co 0.05 Mn 0.05 Al 0.01 O 1.992 Cl 0.016 , and the parameters are listed in Table 1.

[0067] Example 2

[0068] The following steps are used to prepare the chlorine-doped quaternary positive electrode material A2:

[0069] (1) 0.89 mol of spherical nickel hydroxide (average particle size 8.5 μm), 0.01 mol of aluminum hydroxide and 0.05 mol of manganese oxalate were weighed out in a molar ratio of n(Ni):n(Al):n(Mn) = 0.89:0.01:0.05, mixed on a planetary ball mill for 2 h, and a first solid material was obtained;

[0070] (2) 0.035 mol of cobalt acetate and 0.015 mol of cobalt chloride were weighed out in a molar ratio of n(Ni):n(Co) = 0.89:0.05, added to the first solid material, mixed on a planetary ball mill for 2 h, and the obtained mixture was loaded into a crucible, subjected to a first heat treatment under an oxygen atmosphere at a temperature of 700°C for 5 h, and a second solid material was obtained;

[0071] (3) 1.05 mol of lithium hydroxide and 1 mol of the second solid material were weighed out in a molar ratio of n(Li):n(Ni+Co+Mn+Al) = 1.05:1, mixed on a planetary ball mill for 2 h, and the obtained mixture was loaded into a crucible, subjected to a second heat treatment under an oxygen atmosphere at a temperature of 730°C for 15 h, and the obtained solid product was crushed and sieved, and a chlorine-doped quaternary positive electrode material A2 was obtained, with the chemical formula LiNi 0.89 Co 0.05 Mn 0.05 Al 0.01 O 1.992 Cl 0.016 , and the parameters are listed in Table 1.

[0072] Example 3

[0073] A fluorine-doped quaternary positive electrode material A3 was prepared by the following steps:

[0074] (1) 0.92 mol of spherical nickel hydroxide (average particle size 8.8 μm), 0.02 mol of aluminum hydroxide powder and 0.02 mol of manganese carbonate were weighed out in a molar ratio of n(Ni):n(Al):n(Mn) = 0.92:0.02:0.02, mixed on a planetary ball mill for 2 h, and a first solid material was obtained;

[0075] (2) 0.025 mol of cobalt acetate and 0.015 mol of cobalt fluoride were weighed out in a molar ratio of n(Ni):n(Co) = 0.92:0.04, added to the first solid material, mixed on a planetary ball mill for 2 h, and the obtained mixture was loaded into a crucible, subjected to a first heat treatment under an oxygen atmosphere at a temperature of 600°C for 6 h, and a second solid material was obtained;

[0076] (3) 1.06 mol of lithium hydroxide and 1 mol of the second solid material were weighed out respectively according to a molar ratio of n(Li):n(Ni+Co+Mn+Al)=1.06:1, mixed in a planetary ball mill for 3 h, and then the obtained mixture was loaded into a crucible to perform a second heat treatment under an oxygen atmosphere at a temperature of 710°C for 18 h. The obtained solid product was crushed and sieved to obtain a fluorine-doped quaternary positive electrode material A3, the chemical formula of which is LiNi 0.92 Co 0.04 Mn 0.02 Al 0.02 O 1.9895 F 0.021 .

[0077] Example 4

[0078] A bromine-doped quaternary positive electrode material A4 was prepared by the following steps:

[0079] (1) 0.83 mol of spherical nickel hydroxide (average particle size of 8.2 μm), 0.02 mol of aluminum hydroxide and 0.05 mol of manganese oxalate were weighed out according to a molar ratio of n(Ni):n(Al):n(Mn)=0.83:0.02:0.05, and mixed in a planetary ball mill for 2 h to obtain a first solid material;

[0080] (2) 0.08 mol of cobalt carbonate and 0.02 mol of cobalt bromide were weighed out according to a molar ratio of n(Ni):n(Co)=0.83:0.10, and added to the first solid material, which was mixed in a planetary ball mill for 3 h. The obtained mixture was loaded into a crucible to perform a first heat treatment under an oxygen atmosphere at a temperature of 700°C for 5 h to obtain a second solid material;

[0081] (3) 1.06 mol of lithium hydroxide and 1 mol of the second solid material were weighed out respectively according to a molar ratio of n(Li):n(Ni+Co+Mn+Al)=1.06:1, mixed in a planetary ball mill for 3 h, and then the obtained mixture was loaded into a crucible to perform a second heat treatment under an oxygen atmosphere at a temperature of 700°C for 18 h. The obtained solid product was crushed and sieved to obtain a bromine-doped quaternary positive electrode material A4, the chemical formula of which is LiNi 0.83 Co 0.1 Mn 0.05 Al 0.02 O 1.9951 Br 0.0098 .

[0082] Example 5

[0083] An iodine-doped quaternary positive electrode material A5 was prepared by the following steps:

[0084] (1) According to the molar ratio of n(Ni):n(Al):n(Mn) = 0.85:0.02:0.05, 0.85 mol of spherical nickel hydroxide (average particle size 8.2 μm), 0.01 mol of aluminum hydroxide, 0.01 mol of aluminum iodide and 0.05 mol of manganese oxalate were weighed respectively, mixed in a planetary ball mill for 3 h to obtain a first solid material;

[0085] (2) According to the molar ratio of n(Ni):n(Co) = 0.85:0.08, 0.08 mol of cobalt acetate was weighed and added to the first solid material, and the obtained mixture was loaded into a crucible and subjected to a first heat treatment under an oxygen atmosphere at a temperature of 800°C for 6 h to obtain a second solid material;

[0086] (3) According to the molar ratio of n(Li):n(Ni+Co+Mn+Al) = 1.08:1, 1.08 mol of lithium hydroxide and 1 mol of the second solid material were weighed respectively, mixed in a planetary ball mill for 3 h, and the obtained mixture was loaded into a crucible and subjected to a second heat treatment under an oxygen atmosphere at a temperature of 720°C for 18 h. The obtained solid product was crushed and sieved to obtain an iodine-doped quaternary positive electrode material A5, with a chemical formula of LiNi 0.85 Co 0.08 Mn 0.05 Al 0.02 O 1.994 I 0.012 .

[0087] Comparative Example 1

[0088] The quaternary positive electrode material D1 was prepared by the following steps:

[0089] (1) According to the molar ratio of n(Ni):n(Al):n(Mn) = 0.89:0.01:0.05, 0.89 mol of spherical nickel hydroxide (average particle size 8.5 μm), 0.01 mol of aluminum hydroxide and 0.05 mol of manganese oxalate were weighed respectively, mixed in a planetary ball mill for 2 h to obtain a first solid material;

[0090] (2) According to the molar ratio of n(Ni):n(Co) = 0.89:0.05, 0.05 mol of cobalt acetate was weighed and added to the first solid material, and the obtained mixture was loaded into a crucible and subjected to a first heat treatment under an oxygen atmosphere at a temperature of 700°C for 5 h to obtain a second solid material;

[0091] (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+Mn+Al)=1.05:1, mixed in a planetary ball mill for 2 h, and then 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 a quaternary positive electrode material D1, the chemical formula of which was LiNi 0.89 Co 0.05 Mn 0.05 Al 0.01 O2, and the parameters are listed in Table 1.

[0092] Comparative Example 2

[0093] The following steps were adopted to prepare the chlorine-doped quaternary positive electrode material D2:

[0094] (1) 0.89 mol of spherical nickel hydroxide (average particle size of 8.5 μm), 0.01 mol of aluminum hydroxide, and 0.05 mol of manganese oxalate were weighed out according to a molar ratio of n(Ni):n(Al):n(Mn)=0.89:0.01:0.05, mixed in a planetary ball mill for 2 h, and then a first solid material was obtained;

[0095] (2) 0.05 mol of cobalt acetate was weighed out according to a molar ratio of n(Ni):n(Co)=0.89:0.05, and then added to the first solid material, mixed in a planetary ball mill for 2 h, and then a second solid material was obtained by performing a first heat treatment under an oxygen atmosphere at a temperature of 700°C for 5 h;

[0096] (3) 1.02 mol of lithium hydroxide, 0.03 mol of lithium chloride, and 1 mol of the second solid material were weighed out according to a molar ratio of n(Li):n(Ni+Co+Mn+Al)=1.05:1, mixed in a planetary ball mill for 2 h, and then 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 a chlorine-doped quaternary positive electrode material D2, the chemical formula of which was LiNi 0.89 Co 0.05 Mn 0.05 Al 0.01 O 1.991 Cl 0.018 , and the parameters are listed in Table 1.

[0097] Table 1

[0098] Material No. Cell parameter c (nm) Atomic ratio of surface CI element (%) Example 1 A1 1.42467 0.18 Example 2 A2 1.42464 0.12 Comparative Example 1 D1 1.42275 0 Comparative Example 2 D2 1.42371 0.58

[0099] The cell parameters in Table 1 are tested by XRD, and the atomic ratio of surface Cl element refers to the proportion of Cl atoms on the surface of the particles to all atoms on the surface, which is tested by XPS.

[0100] According to the data in Table 1, it can be seen that the cell parameters of halogen-doped quaternary positive electrode materials A1 and A2 prepared by the method of the present disclosure are larger than those of D1-D2, which is beneficial to the transmission of lithium ions; under the condition of the same amount of Cl, the atomic ratio of surface Cl element of A1 and A2 is lower, indicating that halogen is doped into the material.

[0101] XRD tests are performed on A1, A2, D1 and D2, and the results are shown in Figure 3 .

[0102] According to Figure 3 , it can be seen that the peak positions of halogen-doped A1, A2 and D2 are shifted compared with the quaternary positive electrode material D1 without halogen doping; under the condition of the same amount of Cl, the peak position of A1 and A2 is shifted to a greater extent compared with the surface halogen-doped material D2, indicating that the doping degree of Cl element is higher, and at least part of the halogen is doped into the crystal lattice of the material.

[0103] SEM tests are performed on samples A1 and D2 to analyze the element distribution of the samples, and the results are shown in Figure 4 and Figure 5 .

[0104] According to Figure 4 and Figure 5 , it can be seen that the Ni, Co, Mn, Al and Cl elements in A1 are uniformly distributed compared with D2, indicating that the elements in the halogen-doped quaternary positive electrode material prepared by the method of the present disclosure are uniformly distributed.

[0105] Test Example

[0106] Electrochemical performance tests are performed on the quaternary materials A1, A2, D1 and D2 prepared in the examples and comparative examples, and the specific steps are as follows:

[0107] According to the mass ratio of 8:1:1, the positive electrode material, the conductive agent (acetylene black) and the binder (polyvinylidene fluoride) are weighed and uniformly mixed with the solvent (N-methyl pyrrolidone), coated on the aluminum foil and cut into sheets as the positive electrode; and then combined with lithium sheet, 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 is tested, and the results are shown in Figure 1 and 2 .

[0108] Specific test conditions: the charge and discharge voltage range is 2.75-4.3V; the charge and discharge rate is 0.1C for the first 4 times and 0.5C after 5 times, and the test temperature is 35℃.

[0109] According to the above data, it can be known that the rate performance of the halogen-doped quaternary cathode material prepared by the method of the present disclosure is higher. Figure 1

[0110] According to the above data, it can be known that the rate performance of the halogen-doped quaternary cathode material prepared by the method of the present disclosure is higher. Figure 2

[0111] According to the above data, it can be known that the rate performance of the halogen-doped quaternary cathode material prepared by the method of the present disclosure is higher.

[0112] The preferred embodiments of the present disclosure are described in detail above in combination with the drawings, but the present disclosure is not limited to the specific details in the above-described embodiments. Within the technical concept range 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 range of the present disclosure.

[0113] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combination manners are not described again in the present disclosure.

[0114] In addition, the various different embodiments of the present disclosure can also be combined in any manner, as long as it does not deviate from the idea of the present disclosure, and it should also be considered as the disclosed content of the present disclosure.​​

Claims

1. A method for preparing halogen-doped quaternary cathode materials, characterized in that, The method includes the following steps: S1. Nickel hydroxide, aluminum source and manganese 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. At least one of the cobalt source, the manganese source, and the aluminum source contains a halogen; The first solid-phase mixing, the second solid-phase mixing, and the third solid-phase mixing methods include solid-phase ball milling, with times of 1-5 hours respectively.

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 manganese source includes one or more of manganese hydroxide, manganese dioxide, manganese tetroxide, manganese carbonate, manganese oxalate, manganese acetate, manganese fluoride, manganese chloride, manganese bromide, and manganese 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, 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℃.

4. 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.

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

6. 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.

7. Halogen-doped quaternary cathode material prepared by the method according to any one of claims 1-6.

8. The halogen-doped quaternary cathode material according to claim 7, characterized in that, The quaternary cathode material includes particles with the chemical formula LiNi 1-x-y-z Co x Mn y Al z O 2-0.5p X p , where 0.6 ≤ 1 - x - y - z < 1, 0 < x ≤ 0.15, 0 < y ≤ 0.15, 0 < z ≤ 0.1, 0 < p ≤ 0.1, and X is one or more of F, Cl, Br, and I.

9. A lithium-ion battery, the lithium-ion battery comprising a positive electrode, an electrolyte, and a negative electrode, characterized in that, The cathode comprises the halogen-doped quaternary cathode material as described in claim 7 or 8.

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